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Harry BenshoffOccupation / Title:
Harry M. Benshoff is a professor and researcher in media arts, researching extensively about film theory, film genre, multiculturalism, film history, queer theory and animation labour.
In 1985, he graduated from Franklin and Marshall College in Lancaster, Pennsylvania with a BA in English. After three years at Jefferson Medical College in Philadelphia, he decided to pursue film and media studies and received an MA and PhD in Critical Studies from University of Southern California’s School of Cinema-Television. He taught at the University of California before becoming a professor at the University of North Texas.
At the University of North Texas, he teaches several different courses in film, such as “Film and Television Analysis,” “African American Film,” “Lesbian, Gay, and Queer Film and Video,” and “Gender and Sexuality in the Horror Film.” He also conducts a series of “Film Authors” featuring noted directors.
Benshoff has since become an extremely prominent author on several topics in film and media, including queer theory, animation labour, fan cultures, blaxploitation horror films, and Hollywood LSD films. Benshoff authored Monsters in the Closet: Homosexuality and the Horror Film (Manchester University Press, 1997), and co-authored America on Film: Representing Race, Class, Gender and Sexuality at the Movies (Blackwell Publishers, 2004), Queer Images: A History of Gay and Lesbian Film in America (Rowman & Littlefield, 2006) and Queer Cinema: The Film Reader (Routledge, 2004). He has also written essays on Dark Shadows fan cultures, The Talented Mr. Ripley (1999), Brokeback Mountain, and labour representation in Snow White and the Seven Dwarfs (1937).
He has been nominated for the Lambda Literary Award for Science Fiction/Fantasy and the Lambda Literary Award for Drama.


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I’ve heard so many good things about Brandon Sanderson and I’ve been wanting to read one of his books for awhile. I started out with a standalone (SO rare for the fantasy genre).
I think this was the perfect introduction. This story is set in a world where the magic system is powered by color. How cool is that? There’s much more to it, but I think it’s best explained in the book. The pace is a little slow at times, but I never felt so bored that I wanted to quit.
I’m not sure which of his series I want to try out. If anyone has a suggestion, throw it my way. If you’re a fantasy fan or if you want to try it out, I highly suggest Warbreaker. It’s not too complicated that you’ll be confused and it’s a fun storyline.
I love reading books set in Portland. When I heard of this one, I immediately put it on hold at the library.
This is about a teenage girl named Jade from the poor neighborhood of North Portland who attends a prestigious private school in downtown Portland on a scholarship. The book tackles racial and class issues. It’s not a particularly deep or hard-hitting book. But it brings to light some issues that maybe you didn’t consider. Even though I related a lot to Jade as an Asian and as someone who relied on some low-income programs to get a leg up, some of her story still gave me some new things to think about.
I’m not going to give away too much so if you’re curious about specifics about my story and what I learned, feel free to message me.
I hate reading hyped series as the books are released because I have no chill and no patience. I almost always wait and read the whole thing at once. I don’t know why I tortured myself by snatching up the first of The Belles series.
But I couldn’t help myself when I heard about The Belles. The idea of an ugly grayscale population and Belles with the power to bring color and beauty to the people was too intriguing to pass up. It was an interesting read, but predictable at times. I’m curious to see where the story goes so I’ll read the next installation when it comes out.
Four young siblings hear about a woman who could predict a person’s death date. They go to see her and one by one speak to her alone.
The book debates the idea of fate. Does knowing their predicted death date cause the siblings to make certain choices in their lives that lead them to that date. Or will that death date come true regardless of how they live?
I had a hard time putting this book down. I found the Gold siblings so fascinating and so tragic. I highly recommend it to fans of thought-provoking books or literary fiction.
Wow this book made me sad and frustrated. It’s a story about Alice (a manic pixie dream girl type) and an incident with Brandon (the best quarterback their small town has ever seen) told from the perspective of four of their peers.
I was surprised how much the reader learns about Alice and Brandon without ever hearing from them. It was a really cool way to tell a story. However, it did leave some holes in Alice’s story since we don’t see her view. The story is told through rumors and gossip. By the end, most of the truth comes out through bits and pieces.
To me, the last few chapters fell flat. After so much build up, I was expecting more than that. I also wish there was more character development of the four narrators. They came off one-dimensional. I wanted them to show a little more of themselves and show a little more complexity.
But despite my complaints, I devoured the book and I liked it. A solid 3/5 stars.

domain: hobby


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Mandeville, Manchester — Wigton Windfarm Ltd launched a 24MW expansion plant with a ground breaking ceremony close to its existing 38.7MW windfarm complex at Rose Hill in south Manchester.
The work on Wigton III will be carried out by Spanish wind energy company Gamesa under a US$45 million contract.
Construction is scheduled to begin in April with commissioning projected for February 2016.
Planners say that when completed Wigton III will produce 63.072 MWh which will increase renewable energy input to the national grid by more than two per cent.
Speakers at Friday’s ceremony including Energy minister Phillip Paulwell said the new wind energy plant was another step towards the goal of achieving the government’s renewable energy target of 30 per cent by 2030.
The new facility is being projected to reduce Jamaica’s oil consumption by 37,000 barrels annually. The experts claim it should lessen the greenhouse gas pollution caused by fossil fuel use.
The Petrocaribe Development Fund is providing 80 per cent of financing for the project with the remaining 20 per cent coming from Wigton equity. The Petroleum Corporation of Jamaica (PCJ), is the parent company of Wigton.

domain: economics


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TABLE OF CONTENTS
Guide to the Rice University Black Student Association records, 1972-2016 UA 370
Founded at Rice University in the early 1970s, the Black Students’ Union created a safe, welcoming environment for black students at Rice.
Starting in 1972, the Black Students’ Union worked with the administration to start a B.S.U. Center. This morphed into the Office of Multicultural Affairs, which housed the center.
By 1989, the Black Student Association provided another club for black students on campus. In the mid 1990s, the Black Students’ Union combined with the Black Student Association.
This collection consists of items created by the Black Students' Union and the Black Student Association, more specifically, minutes, histories, correspondence, and memorabilia.
Conditions Governing Access
This material is open for research. Stored off-site at the Library Service Center. Please request this material via firstname.lastname@example.org or call 713-348-2586.
Conditions Governing Use
Permission to publish from this material must be obtained from the Woodson Research Center, Fondren Library, Rice University.
Rice Univeristy Black Student Association records, 1972-2016, UA 370, Rice University Archives, Woodson Research Center, Fondren Library, Rice University
Catherine E. Clack donated materials in 2012. Renita King and Akilah Mance donated materials in 2016.
Additional materials are expected for this collection.

domain: library


Skip to comments.1000 Rounds Of 5.56 Just Jumped to $1,495.59
Posted on 03/26/2013 3:47:15 PM PDT by Sawdring
I was browsing for ammunition and found that 1000 rounds of 5.56 NATO Lake City XM855 FMJ 62 Grain Steel Penetrator ammunition just jumped from $999.95 to $1,495.59. If I remember correctly this same ammunition last summer was selling for around $350.00 for a thousand rounds.
Remember, Limbaugh always says the cure for high prices are high prices and they are certainly going up. I also was at Walmart and they had none of the common calibers. No .45, .40, .22LR, 5.56, or .223. Cabela's had plenty of .45 and .40 but no .22LR, 5.56 or .223.
OMG, make it stop.
My local Walmart wanted $22 for 20 rounds of Federal 9mm. It’s nuts.
Cheaper than Dirt is the King of all Gougers. Check Gunbot from time to time. It’s a real time tracker of in stock ammo and it updates automatically. All the stuff that’s a good price goes pretty quick.
Whaaa......buck fifty a round? Ouch.
Why is DHS buying all the ammo who do they intend to shoot with 2 billion rounds of ammmo, 19 hijackers?
what is the role of DHS? is it Obama’s civilian military just as powerful just as well funded as the real military except outside of the Hague convention on hollow points?
Now I’m going to have to pay capital gains tax if I sell any.
Cheaper than Gold...
Dry up demand and put weak dealers out of business. Defacto gun control.
Cheaper than dirt sucks.
I also just bought ar AR-74 just because the ammo is so cheap.
1000 Round Case of Federal 9mm Luger Centrefire - 124 gr FMJ $319.99
I would prefer the Winchester white box.
I ran across some 100-round 9mm Federal value packs today at Walmart, $21 and change. Got my limit. Not bad.
Stop buying from CTD.
At least CTD is making a market.
If you don't like their prices...don't buy.
In the end, a thing is worth what people are willing to pay for it.
I have bought from CTD when I thought I needed that ammo despite the high prices...and I was glad to get it.
Complaining about ammo prices is like complaining about a rising stock market.
I know you aren't a communist, so lay off the commie lingo.
Free markets are not fixed as to price. They fluctuate with supply and demand.
Sitting tight on whatever I have. They have helicopters, tanks and drones. We have the people, and we know the ground we walk on. It’s a 50/50 shot at best, for them. If the odds change we’ll have to go on the offensive - given the most current situation. No other President in my lifetime has given me reason to think this way.
I haven’t bought anything from CTD since they jacked up their prices after the 2008 election.
This whole ammo and guns availability thing has been fascinating to me and totally unpredictable.
First of all I don’t need any ammo except 8mm Mauser and can’t afford much even if it was available.
Just out of curiosity, every time I go to the Wal-Mart Super Center in Defuniak Springs, I check their ammo supply. The next to last time I checked they seemed to be rebuilding their ammo stock and except for AR style, guns too.
I went by yesterday and the gun racks were mostly full but ammo again has dropped. In fact it was the barest I have ever seen it. Even the ones they still had such as shotgun shells and the less common rifle cartridges were gone. I don’t think they had more than a dozen boxes of any kind.
Something strange really is going on. Every now and then I think about making a profit on the huge stock of .22LR I have, but then I would no longer have them.
This is where it has been for weeks now.
I wonder if I need to mark to market the value of my inventory now?
Good post Rooster. I totally agree with you.
Whadda a bunch of cry-babies.
The ammo shortage is being created by gougers. They buy up all the stock and sale it huge mark up. Free market or not, it’s shady and I won’t buy from them. I hope the market recognizes it and punishes them.
I’m gonna pick up another 1,000 rounds of Lake City M855 when I can get the best price. That may be $819.00 per thou.
Chris Rock was prophetic. He said that bullets should cost $1000 per bullet. That way, there would be no innocent bystander victims.
A while back CTD made a statement regrading some of the cost increases on magazines that they were raising the prices to slow down purchases. They were getting more orders than they could handle. Even with the jacked up prices ($99 for a 30 round steel AR magazine) they were still selling out.
Even the USMC is running short of ammo. Do you think they are being victimized by gougers?
DemshateGod...I do appreciate your frustration and I respect your opinion.
I am also p!ssed. But this shortage is pure supply and demand...it isn't due to gouging.
BTW, everything I read online says that the ammo plants are working 24/7 to fill the demand...but the demand is simply outstripping supply.
Hang tough and buy smart.;-)
I bought 1,000 rounds 12ga Remmington Target loads Friday for $483 from a local store. I’m pretty well stocked up, so I haven’t had to gou out and buy any ammo since these crazy prices hit.
To hell with that... They can keep it.
What Rooster said. If you want prices to stabilize, STOP BUYING! Unless you have a dire immediate need, don’t buy ammo for a while. It’s US who are driving up prices by depleting stocks. Simple economics.
Good. High prices on limited-supply high-demand goods means it’s available to those needing it. The cost of “out of stock” is much much higher.
When I'm in the market for ammo or some mags, I keep it opened and minimized. It saves me $$$ every time I use it for a purchase!
Where is it? I want it.
I have heard some odd rumors and even from my local Walmart that they are upset with the in store purchases and hoarding where the dock managers are buying the stock much like an office pool with other employees and then selling the stock online and splitting the profits.
So to counter this shipments for the most part are being restricted and soon they will just send in a mass load of aisle filling pallets and with security on hand and purchase limits will then sell. Our local WM in Alaska does that all the time, they get a massive inventory dump on the store about once a month, its cheaper to ship in bulk at one time instead of a constant daily restocking.
Yes they have these and WE THE PEOPLE know were the pilots and drivers live.
No 9mm at the Walmarts I have been to, they did have Winchester 45 ACP for the same price.
Do what I do.. Reload...
I made 950 rounds of .223 plinking rounds. Cost me about $120
Tonight I start on 500 rounds of 6.8 SPC.
Grab the rifle calibers. .243; .270; .308; .30-06. Don’t let the bastards get within 250 yards of you and yours.
Cheaper than Platinum (for now)
There ought to be an on-line list. I agree, though. Good to know what they drive, where they eat, gas up, etc., too.
I actually hate reloading .223, especially on a single stage.
I’ll just say the stock I have on hand in relation to the current prices would buy me a new truck. I have even considered a barter situation locally. Got me some nice pet loads using of all things the Barnes Triple shocks in the .308 for a gas gun, no super ultra velocity but distinctive and consistent terminal hunting results much better than I have seen using A frames or Trophy Bondeds.
Sure its an all copper bullet but they WORK!
We haven’t seen the volume business model or business approvals of competition for decades. When the craze stops and dries up sales, instead of lowering prices, they’ll cut production. Lumber is a good contemporary example. And as for most big business interests, they’re now government-linked commies, sucking up to their politically correct relatives in government and academia. Look at the political candidates they allow in their “gatekeeping” now: socialist trash, all. I worked contract jobs in offices of many companies during the ‘90s and only saw the politics of social and fiscal leftism in those places. Some of the “chairpersons” were even foreigners hostile toward Americans and especially hostile to men.
CTD is the highest priced of those that have AR ammo. And that Lake City 5.56 wasn’t $350 last year.
Today I bought Independence 5.56 55 grain for $10.99 a box of 20 at my local gun store. Unusual of course. But they have had Lake City 5.56 in ammo boxes of 900 rounds for $750 the last 2 weeks.
Not my first choice, but they have WPA Classic .223 for $460 a thousand today. Works fine in my RRA, but adds a good bit of time to the cleaning of the firearm.
You want to find ammo, don’t shop online, find smaller local gun shops.
Hornady’s web site says that 5% of their sales go to the gummermint.
Bottom line is that thinking people in this country are seriously arming up. For good reason, IMO. And, I think that this current shortage is a fair price to pay for that, and the awakening that is responsible for it. Crunch time is coming my friend.


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Discussion in 'Pop & Justice' started by Noir, Nov 27, 2014.
Ugh. Frustrating but not surprising. I hate that those bops are lost.
It's especially weird that you can't even buy the As If! EP (or Obsession for that matter, though it's 'soundtrack exclusive') from iTunes anymore. Thank god I was enough of a fag in 2011 to snag it then!
Yeah, I’m so glad I have it on CD along with the others. Things like this only reaffirm how necessary physical media is (or at the very least purchasing the digital files)
I have the As If! EP on my phone and it’s such a treasure that I forget about from time to time. I’m now also contemplating buying the Larry Crowne soundtrack just to get Obsession in HQ.
99 Tears should never be hidden or forgotten.
It is so endlessly frustrating whenever I go to Spotify to look for it and it's not there, because I never remember. A pop masterpiece.
I caved and added it to my Local Files recently but I wish it was on streaming, it deserves to be! She would never but I’d die if she resurrected some of the tracks (99 Tears!!) in her live set.
"99 Tears" and "108" live in my head and heart rent-free. Capitol Records will not see heaven for their pop sins!
17 is a fantastic song and yet it's nowhere to be found.
"108" is in her top 5.
That’s what made me seek out the EP earlier today. It suddenly popped into my head and I remembered how much I used to bop to it.
I... don't know if I've ever listened to her pre-Night Time, My Time stuff, which isn't surprising if it's become harder to find over the years I guess?
I'm really hoping that we don't have to wait 3 years for the next single.
As If! and Ghost EPs are a must. As are the two singles 17 and One.
There are a handful of other songs and collaborations that you can ignore. I want to say her demos are great too, but I don't think I have listened to them all and frankly I've been indifferent towards them because I've lost patience with Sky!
Very much here for the 108 love! As someone who's tapped in and out at times I'm never sure how her pre-Ghost material is perceived in the fanbase.
I got an ancient pain
I lost my wings and fell to earth
And then I wouldn't stay in my golden cage
So I gave up everything
Is still probably my favorite verse from her.
Justice for the Cry Baby album, honestly. I remember when she said she’d release it if she got Night Time, My Time out dd
Sky Tonia, it's time to officially release First Base and get that viral tiktok smash that's just waiting to happen!
We'll go to first base, and we'll play doctor
We're gonna get high, knock you off your rocker
Staying up all night
99 Tears gripped my ears and put them in a vice this week, that's how strong the hold has been.
She was seen visiting the double grave of the Don't Forget video / Masochism album last night
The radio silence after the single drop kii. I wonder what the 3rd relaunch attempt single will be next year.
Releases a song called ‘Don’t Forget’.
Promptly forgets about it.
That’s so Sky!!!
Separate names with a comma.


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If we visualize each of the areas of imbalance like a seesaw then it either tips to the left, remains level or tips to the right. We can then assign different qualities to these areas as follows:
|Mental||Inward Imbalance||Balanced||Outward Imbalance|
|Physical||Chronic Pain||Pain-free||Acute Pain|
Each of these areas is amplified below. All a person needs to do is pick one area of balance/imbalance from each category and note the associated number.
So for example, if you were experiencing doubt (1) together with stress (6) but had no physical pain (8) you would record the 3 digit number 168.
|(1) Inward Imbalance: lack of enthusiasm, self-obsessed, fear of the unknown, keeps problems to oneself, dwells on the past.|
|(3) Outward Imbalance: over-enthusiasm, overcare for others, fear of the known, wants to talk about problems, concerned about the future.|
|(4) Repressed Emotions: hopelessness, worry, fear of failure, guilt, shame, envy, jealousy, loneliness.|
|(5) Balanced Emotions|
|(6) Expressed Emotions: anger, frustration, fear, sadness, grief, stress, despair, depression.|
|(7) Chronic Pain: Chronic pain lasts for a long period of time and is deep seated. Examples: allergies, kidney stones, migraines and autoimmune.|
|(9) Acute Pain: Acute pain starts suddenly and is short-term. Examples: headaches, toothache, sports injuries, nerve pain and referred pains.|
There are 27 different combinations and each has a Therapeutic resonance associated with it. For the number above 168 you can seen from the table below that this would correspond to a frequency of 531.316 kHz.
This number is then entered into one channel of the dual signal generator. When coupled to the special double coils it will create an Energy field as big as a house. The idea is that you then bathe in the field which is designed to help restore balance and reduce the dis-ease.
At present we are trialling the following therapeutic remedies:
Hay Fever: 469.234

domain: psychology


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I have been able to read a great many things recently that I would not have normally picked up - and it is two stories by Mansfield that I have had to read for my 20th Century British Literature class.
The first of the two stories that I had to read by Katherine Mansfield for this class was a story known as "The Garden Party."
The mood of the world that even the well-to-do women of Mansfield's time inhabited is shown here as a sobering piece of contrast to the downright dire situation that poor women lived in.
Some historical context (the result of having to scour the local library for books on Mansfield and Virgina Woolf in order to write a paper for my 20th Century British Lit class) - in the wee years of modern Feminism, women were oftentimes seen as near-useless when not helping a man or men out, not aided in the least by the fact that women in the late 19th century to the early 20th century actually by far outnumbered the men, so that there created what was then called a "Spinster crisis" - too many women, not enough men to marry them to equaled too many unmarried aunties, sisters and daughters and no idea what to do with these people who were emotionally hobbled into a strict code of behavior that could only have them ever hope to be a wife, a mother, a nun or a servant. Thus a crisis involving people who could not get work on their own, but nevertheless needed to eat and live somewhere - almost always a male relative's home.
With the historical context over with, we can move on to the story of "The Garden Party" itself. The protagonist of this story, Laura, makes herself feel complacent in the insular world that she inhabits in the prettiest house in town - so much so that she does not venture out into the part of the road down the house, where the poor people live. A story about growing up - not just Laura, but, perhaps, also the society that she lived in - this is a wonderful story that feels enormous in it's seemingly simple message, and feels hopeful in the camaraderie that Laura shared with her similarly named brother, Laurie, as well as their seemingly shared ability to really see the world around them in a way that the other people in their lives just cannot.
In the second story that we read by Mansfield in my class, we then read The Doll's House, a story that I would argue is a good deal more subtle and a great deal less optimistic towards the good will of the upper class and the hope for an older generation of women than the previous story did. Well, I would say that the older generation of women shown in both stories was quite pessimistic, but after seeing from the uncomfortable point of view of the cruelly oppressive - yet, herself, oppressed - Aunt Beryl, we get quite a dire and pessimistic view of whatever hope we can have for women in her situation. Perception seems to be a mark of "worthiness" that can transcend class boundaries, and Mansfield subtly applies this theme as an antidote, of sorts, to the cool indifference that the Burnells are subjected to.
I ended up liking both of these stories more than anything else in the class, even more than the Woolf novella that we ended up reading - "Between the Acts" - and it also beat out the disturbing, last novel that we read, Disgrace by J. M. Coetzee.
If I had any complaints about the stories, it would have to be due to their age - I got confused in a few moments, due to the simple fact that the stories were written originally for a different audience than the one I am in. "The Doll's House" was a less aged piece - I would say that if one could stand the eventual test of time, it would have to be this story, as opposed to the sometimes head-scratching confusion of trying to understand the clothing, the social conventions and the language apparent in "The Garden Party".


ome has a uniquely peculiar relationship with freezing weather. In most European capitals, people bundle up. Here, they vanish. Or some do. It’s as if cold contained a malarial dimension. Busy streets grow vacant. A past-midnight excursion to St. Peter’s Square in below-freezing cold stands to reward you with literally monumental solitude.
Admittedly, Romans are a Latin tribe, far more thin-skinned than Anglos, Gauls or Slavs. The North’s barbarian chills undo their composure in a flash. When such chill does come, the words morsa and gelo, bite and freeze, appear prominently in mass media as if a famished hound had descended from upper Russia to snack on the unsuspecting.
Those who dare face up to freezing weather — and God forbid wind — dress like arctic people. Jackets are fattened with scarves. Those who undertake the near criminal act of “walking” their babies must first ensure the infants are tucked under several dozen layers of mommy-cotton. They look less like children than carpets being pushed from place to place.
I like the cold. It brings silence. The tribal yack of the alley below stops altogether. The small palazzo where I live seems suddenly uninhabited. The custodian dons Siberian gear, at the ready to join Italian troops in some imagined Stalingrad trek. The only available conversation concerns the “impossible” cold — +1C or, far more alarming, -2C — and how long it might last. The expression “you’ll catch your death of cold” is transformed into a stay-at-home order as Rome defers to ice age lassitude.
There’s charm to all of this. If North Americans pride themselves in dealing with and overcoming all, Romans prefer a kind of stylized cowering. They pour billions into the bubble-wrap windbreaker industry. They complain. They insult the sun for not doing its job. Bitter cold is drama, like hurricanes or typhoons elsewhere.
But only the homeless and vagrants, most unaccustomed to sudden plunges in winter temperatures, suffer actual drama. There’s nowhere to go. Some freeze to death under bridges like Parisian clochards of another time. These stories are reported in lugubrious detail, with sadly romantic language that can make you think you’re reading a variation on Hans Christian Andersen’s “The Little Match Girl.” The phrases senza fissa dimora (no fixed address) and freddo intenso nella note (intense nighttime cold) become the lyrics of a cruel winter poem. Snow on beaches is a paradox that journalists struggle to comprehend. Again, cold induces naiveté, if not wonder — the seldom seen of things improbably made available on south Italy’s forever eccentric stage.
Rome cold reminds me of a story my father once told me about air crossing between London and New York in the 1940s. In those days, prop planes stopped to refuel in Gander, Newfoundland. On his military flight was an Indian family from Bombay, including two young children. They were on their way to Washington. The plane landed in Gander during a snowstorm. But the children had never seen snow. One was frightened, at least a first, the other frolicked across the tarmac, amazed. For them, something new had dawned, as it seems to for Romans every time the temperature dips teasingly below freezing mark, thus slowing the limbs of the Latin world and making babies into mummies for as long as it takes to remind the one or many gods of sunny Italy that their sworn duty is to keep southerners warm.


321 Move has seen a huge upsurge in homeowners looking for a quick house sale as they take advantage of the new stamp duty holiday.
Online PR News – 28-October-2020 – Leeds, West Yorkshire – 321 Move, a property company with offices in Leeds and London has seen a huge upsurge in homeowners looking for a quick house sale as they take advantage of the new stamp duty holiday.
The recent stamp duty holiday has encouraged many to take advantage of savings of up to £15,000 on their next house sale. The temporary holiday applies to all property sales in England and Northern Ireland on the first £500,000. The aim of the stamp duty holiday is to boost the UK property market after it remained stagnant throughout lockdown and to help those affected financially by Covid-19. Unsurprisingly, the prospect of stamp duty savings has led to an increase in house sales across the UK and the North of England.
A spokesperson for 321 Move said, “In this case, we’ve seen a huge increase in those looking to for a speedy house sale, without the hassle of the traditional estate agent route, where long waiting times and chains can cause a lot of stress for those who are worried about missing out on their dream home.”
“To avoid missing out on the stamp duty holiday, you may need to sell your house fast. Homeowners come to property buying companies such as 321 Move for a variety of reasons, especially when looking for a speedy house sale. They may be interested in selling an inherited house or looking to maximise their spend after a divorce or separation.”
321 Move have more than a decade of experience in the property sector. They pride themselves on offering a professional, experienced, and cost-effective service across sales, maintenance, lettings, and development.
The 321 Move team understand that traditional methods of selling a house can be costly and time-consuming. They help others to sell their house fast, in a hassle-free simple way – whether you’re selling a house through probate or selling after a separation.
For more information, visit 321move.co.uk.


READYLIFT 2" LEVELING KIT
The ReadyLift 66-2299 2" Leveling Kit is an easy way to lift the front end of your 1999-2016 Ford F-250/350 2WD Pickup. Using our time tested CNC machined 6061-T6 design technology, ReadyLift has the perfect leveling solution for 2WD Super Duty owners. If you want to level your truck the right way, the only way is with ReadyLift.
Featuring a machined aluminum spacer for precision fit and installation. The aluminum construction will not deform or deteriorate over time like other cheap leveling kits on the market. A zinc-plated steel spring retainer stud extender is included to insure proper fit and function. Easy to install while allowing you to maintain use of your factory shocks! Even better is that you now can get the leveling lift you want all while maintaining the factory ride!
Features & Details:


1. ____________________________________________ Solar Energy System Design The largest solar electric generating plant in the world produces a maximum of 354 megawatts (MW) of electricity and is located at Kramer Junction, California. This solar energy generating facility, shown below, produces electricity for the Southern California Edison power grid supplying the greater Los Angeles area. The authors’ goal is to provide the necessary information to design such systems.
The solar collectors concentrate sunlight to heat a heat transfer fluid to a high temperature.The hot heat transfer fluid is then used to generate steam that drives the power conversion subsystem, producing electricity. Thermal energy storage provides heat for operation during periods without adequate sunshine. [pic] Figure 1. 1 One of nine solar electric energy generating systems at Kramer Junction, California, with a total output of 354 MWe. (photo courtesy Kramer Junction Operating Company) Another way to generate electricity from solar energy is to use photovoltaic cells; magic slivers of silicon that converts the solar energy falling on them directly into electricity.Large scale applications of photovoltaic for power generation, either on the rooftops of houses or in large fields connected to the utility grid are promising as well to provide clean, safe and strategically sound alternatives to current methods of electricity generation. [pic] Figure 1.
2 A 2-MW utility-scale photovoltaic power system co-located with a defunct nuclear power plant near Sacramento, California. (photo courtesy of DOE/NREL, Warren Gretz) The following chapters examine basic principles underlying the design and operation of solar energy conversion systems such as shown in Figure 1. 1 and 1. 2.This includes collection of solar energy, either by a thermal or photovoltaic process, and integration with energy storage and thermal-to-electric energy conversion to meet a predefined load.
Study of the interaction of these subsystems yields the important guidelines for the design of optimal solar energy systems. System design tools are provided to produce optimal sizing of both collector field and storage so that optimum system designs can be produced. Since our emphasis is on the design of entire solar energy conversion systems rather than design of its individual components, both thermal and photovoltaic systems are included.This novel approach results from recognition of the commonality of most system design considerations for both types of solar energy systems. We will not dwell on the intricacies of individual component design, but instead encourage the designer to take experimental (or predicted) component input/output information and incorporate this into an overall system design. The system shown in Figure 1. 1 employs parabolic trough line-focus collectors.
We will cover this and other types of collectors for capturing the sun’s energy including flat plate, parabolic dish, central receiver and photovoltaic collectors.The purpose of a solar collector is to intercept and convert a reasonably large fraction of the available solar radiation. For solar thermal systems this energy is converted into thermal energy at some desired temperature and then, maybe, into electricity. For photovoltaic systems as shown in Figure 1. 2, intercepted solar energy is converted directly into low voltage direct current electricity.
The engineering tradeoff between cost and performance of the components necessary to perform these processes has led to a wide variety of collector and system designs.Reviews of solar collector designs representative of the different concepts that have been built and tested are presented here. The following sections serve as an overview of the solar energy system design process. They follow in a general manner, the flow of logic leading from the basic solar resource to the definition of an operating solar energy conversion system that meets a specified demand for either thermal or electrical energy. 1. 1 The Solar Energy Conversion System There are many different types of solar energy systems that will convert the solar resource into a useful form of energy.
A block diagram showing three of the most basic system types is shown as Figure 1. 3. In the first diagram , the solar resource is captured and converted into heat which is then supplied to a demand for thermal energy (thermal load) such as house heating, hot water heating or heat for industrial processes.
This type of system may or may not include thermal storage, and usually include an auxiliary source of energy so that the demand may be met during long periods with no sunshine. [pic] Figure 1. 3 Diagram of a basic solar energy conversion systems.
The AUX. box represents some auxiliary source of thermal or electrical energy.If the demand (load) to be met is electricity (an electrical load) rather than heat, there are two common methods of converting solar energy into electricity. One method is by collecting solar energy as heat and converting it into electricity using a typical power plant or engine; the other method is by using photovoltaic cells to convert solar energy directly into electricity. Both methods are shown schematically in Figure 1. 3. In general, if solar energy conversion systems are connected to a large electrical transmission grid, no storage or auxiliary energy supply is needed.
If the solar energy conversion system is to be the only source of electricity, storage and auxiliary energy supply are usually both incorporated. If the thermal route is chosen, storage of heat rather than electricity may be used to extend the operating time of the system. Auxiliary energy may either be supplied either as heat before the power conversion system, or as electricity after it. If the photovoltaic route is chosen, extra electricity may be stored, usually in storage batteries, thereby extending the operating time of the system. For auxiliary power, an external electricity source is the only choice for photovoltaic systems. .
2 The Solar Resource The basic resource for all solar energy systems is the sun. Knowledge of the quantity and quality of solar energy available at a specific location is of prime importance for the design of any solar energy system. Although the solar radiation (insolation) is relatively constant outside the earth’s atmosphere, local climate influences can cause wide variations in available insolation on the earth’s surface from site to site.
In addition, the relative motion of the sun with respect to the earth will allow surfaces with different orientations to intercept different amounts of solar energy.Figure 1. 4 shows regions of high insolation where solar energy conversion systems will produce the maximum amount of energy from a specific collector field size. However, solar energy is available over the entire globe, and only the size of the collector field needs to be increased to provide the same amount of heat or electricity as in the shaded areas. It is the primary task of the solar energy system designer to determine the amount, quality and timing of the solar energy available at the site selected for installing a solar energy conversion system. [pic] Figure 1. Areas of the world with high insolation.
Just outside the earth’s atmosphere, the sun’s energy is continuously available at the rate of 1,367 Watts on every square meter facing the sun. Due to the earth’s rotation, asymmetric orbit about the sun, and the contents of its atmosphere, a large fraction of this energy does not reach the ground. In Chapter 2, we discuss the effects of the atmospheric processes that modify the incoming solar energy, how it is measured, and techniques used by designers to predict the amount of solar energy available at a particular location, both instantaneously and over a long term.As an example of the importance of the material discussed in Chapter 2, Figure 1. 5 shows the variation of insolation over a full, clear day in March at Daggett, California, a meteorological measurement site close to the Kramer Junction solar power plant described previously.
The outer curve, representing the greatest rate of incident energy, shows the energy coming directly from the sun (beam normal insolation) and falling on a square meter of surface area which is pointed toward the sun. The peak rate of incident solar energy occurs around 12:00 noon and is 1,030 Watts per square meter.Over the full day, 10. 6 kilowatt-hours of energy has fallen on every square meter of surface area as represented by the area under this curve. [pic] Figure 1. 5 Insolation data from Daggett, California on a clear March day.
The middle curve represents the rate of solar energy falling on a horizontal surface at the same location. For reasons to be discussed later this curve includes both the energy coming directly from the sun’s disc, and also that scattered by the molecules and particles in the atmosphere (total horizontal insolation). This scattered energy is shown as the bottom curve (diffuse insolation).Over the entire day, 6. 7 kilowatt-hours of solar energy fall on every square meter of horizontal surface, of which 0. 7 kilowatt-hours comes from all directions other than directly from the sun. Techniques for estimating the temporal solar resource at any site on the face of the earth are presented in Chapter 2.
In addition, the development and use of computerized meteorological data files is described. These data files based on long-term actual observations, form the time-dependent database of the computerized performance computations contained within this book and, indeed, much of the solar literature.An example of a complete set of beam normal insolation data for a given location is shown in Figure 1.
6. Here we see hourly insolation data, summarized over a day, for each month of a year. With this type of data for a specific site, it is possible to predict accurately the output of a solar energy conversion system, whether it is a low temperature thermal system, a high temperature thermal system or a photovoltaic system. [pic] Figure 1.
6 Time and date description of the global, horizontal insolation solar resource for Cairo Egypt.In addition to estimating the amount of energy coming from the sun, the solar designer must also be able to predict the position of the sun. The sun’s position must be known to predict the amount of energy falling on tilted surfaces, and to determine the direction toward which a tracking mechanism must point a collector. Chapter 3 discusses the computation of the position of the sun with respect to any given point on the face of the earth.
Using only four parameters (latitude, longitude, date and local time), equations are derived to determine the location of the sun in the sky.A characteristic fundamental to the capture of solar energy is that the amount of energy incident on a collector is reduced by a fraction equal to the cosine of the angle between the collector surface and the sun’s rays. Knowing the position of the collector (or any other surface for that matter) and the position of the sun equations in Chapter 3 may be used to predict the fraction of incoming solar energy that falls on the collector. These include situations where the collector is fixed or is tracked about a single axis, no matter what the orientation. 1.
3 Solar Collectors The solar collector is the key element in a solar energy system.It is also the novel technology area that requires new understandings in order to make captured solar energy a viable energy source for the future. The function of a solar collector is simple; it intercepts incoming insolation and changes it into a useable form of energy that can be applied to meet a specific demand. In the following text, we will develop analytical understandings of flat-plate and concentrating collectors, as used to provide heat or electricity.
Each type is introduced below. Flat-plate thermal solar collectors are the most commonly used type of solar collector. Their construction and operation are simple.A large plate of blackened material is oriented in such a manner that the solar energy that falls on the plate is absorbed and converted to thermal energy thereby heating the plate. Tubes or ducting are provided to remove heat from the plate, transferring it to a liquid or gas, and carrying it away to the load.
One (or more) transparent (glass or plastic) plates are often placed in front of the absorber plate to reduce heat loss to the atmosphere. Likewise, opaque insulation is placed around the backside of the absorber plate for the same purpose. Operating temperatures up to 125oC are typical.Flat plate collectors have the advantage of absorbing not only the energy coming directly from the disc of the sun (beam normal insolation) but also the solar energy that has been diffused into the sky and that is reflected from the ground. Flat plate thermal collectors are seldom tracked to follow the sun’s daily path across the sky, however their fixed mounting usually provides a tilt toward the south to minimize the angle between the sun’s rays and the surface at noontime.
Tilting flat-plate collectors toward the south provides a higher rate of energy at noontime and more total energy over the entire day. Figure 1. shows an installation of flat-plate thermal collectors.
[pic] Figure 1. 7 Flat-plate thermal solar collectors for providing hot water. (photo courtesy of DOE/NREL, Warren Gretz) Flat-plate photovoltaic collectors contain an array of individual photovoltaic cells, connected in a series/parallel circuit, and encapsulated within a sandwich structure with the front surface being glass or plastic.
Solar energy falls directly upon the photovoltaic cell front surface and produces a small direct current voltage, providing electrical energy to a load. Unlike thermal collectors however, the backside of the panel is not insulated.Photovoltaic panels need to loose as much heat as possible to the atmosphere to optimize their performance. Like flat-plate thermal collectors, flat-plate photovoltaic collectors (panels) absorb both energy coming directly from the sun’s disc, and diffuse and reflected energy coming from other directions. In general, flat-plate photovoltaic panels are mounted in a fixed position and tilted toward the south to optimize noontime and daily energy production. However, it is common to see flat-plate photovoltaic panels mounted on mechanisms that track the sun about one tilted axis, thereby increasing the daily output of the panels. pic] [pic] [pic] Figure 1. 8 Flat-plate photovoltaic collector applications.
(photos courtesy of DOE/NREL, Warren Gretz) When higher temperatures are required, concentrating solar collectors are used. Solar energy falling on a large reflective surface is reflected onto a smaller area before it is converted into heat. This is done so that the surface absorbing the concentrated energy is smaller than the surface capturing the energy and therefore can attain higher temperatures before heat loss due to radiation and convection wastes the energy that has been collected.Most concentrating collectors can only concentrate the parallel insolation coming directly from the sun’s disk (beam normal insolation), and must follow (track) the sun’s path across the sky. Four types of solar concentrators are in common use; parabolic troughs (as used in the Kramer Junction, California solar energy electricity generating plant shown in Figure 1.
1), parabolic dishes, central receivers and Fresnel lenses. Figure 1. 9 shows these concepts schematically. [pic] Figure 1.
9 Three commonly used reflecting schemes for concentrating solar energy to attain high temperatures.A parabolic trough concentrates incoming solar radiation onto a line running the length of the trough. A tube (receiver) carrying heat transfer fluid is placed along this line, absorbing concentrated solar radiation and heating the fluid inside. The trough must be tracked about one axis. Because the surface area of the receiver tube is small compared to the trough capture area (aperture), temperatures up to 400oC can be reached without major heat loss. Figure 1. 10c shows one parabolic trough from the Kramer Junction, California field shown in Figure 1.
1. A parabolic dish concentrates the incoming solar radiation to a point.An insulated cavity containing tubes or some other heat transfer device is placed at this point absorbing the concentrated radiation and transferring it to a gas. Parabolic dishes must be tracked about two axes.
Figure 1. 10b shows six 9kWe parabolic dish concentrators with Stirling engines attached to the receiver at the focus. A central receiver system consists of a large field of independently movable flat mirrors (heliostats) and a receiver located at the top of a tower. Each heliostat moves about two axes, throughout the day, to keep the sun’s image reflected onto the receiver at the top of the tower.The receiver, typically a vertical bundle of tubes, is heated by the reflected insolation, thereby heating the heat transfer fluid passing through the tubes. Figure 1.
10a shows the 10 MWe Solar One central receiver generating plant at Daggett, California with its adjoining steam power plant. A Fresnel lens concentrator, such as shown in Figure 1. 10d uses refraction rather than reflection to concentrate the solar energy incident on the lens surface to a point.
Usually molded out of inexpensive plastic, these lenses are used in photovoltaic concentrators.Their use is not to increase the temperature, but to enable the use of smaller, higher efficiency photovoltaic cells. As with parabolic dishes, point-focus Fresnel lenses must track the sun about two axes. [pic] Figure 1.
10a A central receiver system. (courtesy of Sandia National Laboratories, Albuquerque) [pic] Figure 1. 10b Two-axis tracking parabolic dish collectors. (courtesy of Schlaich, Bergermann und Partner) [pic] Figure 1. 10c A single-axis tracking parabolic trough collector. (courtesy of Kramer Junction Operating Company) [pic] Figure 1. 0d A concentrating photovoltaic collector using Fresnel lenses. (courtesy of Amonix Corp.
) 1. 4 Need for Storage Like with any other power plant, solar power plant output must satisfy the demands of the utility market. During peak demand periods, kilowatt-hour prices are high and financial incentives are high for guaranteed supply. Solar plant input is limited by diurnal, seasonal and weather-related insolation changes. In order to cope with these fluctuations, the solar plant input may be backed up by fossil fuels, or the solar changes may be mitigated by a buffering storage system.
The choice depends on demands, system and site conditions, the relationship between storage capacity and collector area is discussed in Chapter 10. In thermal solar power plants, thermal storage and/or fossil backup act as: • an output management tool to prolong operation after sunset, to shift energy sales from low revenue off-peak hours to high revenue peak demand hours, and to contribute to guaranteed output • An internal plant buffer, smoothing out insolation charges for steadying cycle operation, and for operational requirements such as blanketing steam production, component pre-heating and freeze protection.Photovoltaic plants in general need no internal buffer, and output management can be achieved with battery or other electrochemical storage, pumped hydroelectric storage, or with diesel-generator backup. The implications of battery storage are discussed in Chapter 10.
[pic] Figure 1. 11 Stored solar energy provides a firm capacity of 31MW until midnight at which time fossil fuel backup us used. 1. 5 Integration with Power Cycles Because of their thermal nature, all the solar thermal technologies can be hybridized, or operated with fossil fuel as well as solar energy.Hybridization has the potential to increase the value of concentrating solar thermal technology by increasing its availability and dispatchability, decreasing its cost (by making more effective use of power generation equipment), and reducing technological risk by allowing conventional fuel use when needed. Although an interconnected field of solar thermal collectors and thermal energy storage may be sufficient for providing high temperature heat directly to a thermal demand, a power generation subsystem must be incorporated into the system design if mechanical work or electrical power is to be an output from the system.Chapter 11 reviews the technology for power generation with particular emphasis on power generation units suitable for interfacing with solar thermal energy collection subsystems. The inclusion of power generation in a solar thermal energy design presents a challenge in selecting the appropriate design conditions.
The efficiency of a power generation unit usually increases with the operating temperature of the power generation cycle, whereas the efficiency of solar collectors decreases with temperature. A tradeoff must be performed to determine the best system design point. [pic]Figure 1.
12 One of the steam cycle power cycles at the Kramer Junction solar energy generating system. (photo courtesy of DOE/NREL, Warren Gretz) 1. 6 Site Qualification Solar technologies using concentrating systems for electrical production require sufficient beam normal radiation, which is the beam radiation which comes from the sun and passes through the planet’s atmosphere without deviation and refraction. Consequently, appropriate site locations are normally situated in arid to semi-arid regions.
On a global scale, the solar resource in such regions is very high.More exactly, acceptable production costs of solar electricity typically occur where radiation levels exceed about 1,700 kWh/m? -yr, a radiation level found in many areas as illustrated in Figure 1. 4. Appropriate regions include the southwest United States, northern Mexico, the north African desert, the Arabian peninsula, major portions of India, central and western Australia, the high plateaus of the Andean states, and northeastern Brazil. Promising site locations in Europe are found in southern Spain and several Mediterranean islands. [pic] Figure 1. 3 A View of Kuraymat (Egypt), the envisaged site for a solar thermal power plant in the Egyptian desert with cooling water from the Nile and connections to the national high voltage grid.
Solar electricity generation costs and feasibility of the project highly depend on the project site itself. A good site has to have a high annual beam insolation to obtain maximum solar electricity output. It must be reasonably flat to accommodate the solar field without prohibitive expensive earth works. It must also be close to the grid and a substation to avoid the need to build expensive electricity lines for evacuating the power.It needs sufficient water supply to cover the demand for cooling water of its steam cycle. A backup fuel must be available for granting firm power during the times when no solar energy is available.
Access roads must be suitable for transporting the heavy equipment like turbine generators to the site. Skilled personnel must be available to construct and operate the plants. Chapter 13 reviews the criteria, methodology and examples of site selection and qualification for solar plants. 1.
7 Economic and Environmental ConsiderationsThe most important factor driving the solar energy system design process is whether the energy it produces is economical. Although there are factors other than economics that enter into a decision of when to use solar energy; i. e. no pollution, no greenhouse gas generation, security of the energy resource etc. , design decisions are almost exclusively dominated by the ‘levelized energy cost’. This or some similar economic parameter, gives the expected cost of the energy produced by the solar energy system, averaged over the lifetime of the system.In the following chapters, we will provide tools to aid in evaluating the factors that go into this calculation. Commercial applications from a few kilowatts to hundreds of megawatts are now feasible, and plants totaling 354 MW have been in operation in California since the 1980s.
Plants can function in dispatchable, grid-connected markets or in distributed, stand-alone applications. They are suitable for fossil-hybrid operation or can include cost-effective storage to meet dispatchability requirements.They can operate worldwide in regions having high beam-normal insolation, including large areas of the southwestern United States, and Central and South America, Africa, Australia, China, India, the Mediterranean region, and the Middle East, . Commercial solar plants have achieved levelized energy costs of about 12-15? /kWh, and the potential for cost reduction are expected to ultimately lead to costs as low as 5? /kWh. [pic] Figure 1.
14 Projections of levelized electricity cost predictions for large scale solar thermal power plants.Current costs are shown in blue with a 1-2 cent/kWh addition for ‘green’ power shown in green. 1. 8 Summary The authors’ overall objective is to illustrate the design of solar energy systems, both thermal and photovoltaic types. To do this, we examine the solar resource and the ability of various types of solar collectors to capture it effectively.
Design tools are developed which integrate performance of isolated solar collectors, along with energy storage, into a larger system that delivers either electrical or thermal energy to a demand.We show as many examples as possible, both graphic and photographic of these systems and their components. It is our hope that once the simplicity of solar energy system design is understood, engineers and manufacturers will provide new system designs that will expand the solar market worldwide and permit all to benefit from this clean, sustainable and distributed source of energy. [pic]3. The Sun’s Position In order to understand how to collect energy from the sun, one must first be able to predict the location of the sun relative to the collection device.In this chapter we develop the necessary equations by use of a unique vector approach. This approach will be used in subsequent chapters to develop the equations for the sun’s position relative to a fixed or tracking solar collector, (Chapter 4) and the special case of a sun-tracking mirror reflecting sunlight onto a fixed point (Chapter 10). Once developed, the sun position expressions of this chapter are used to demonstrate how to determine the location of shadows and the design of simple sundials.
In outline form, our development looks like this: o Earth-sun angles Time o Standard time zones o Daylight savings time o Sidereal time o Hour angle [pic][pic][pic] o Solar time o Equation of time o Time conversion o Declination angle [pic][pic][pic][pic][pic][pic] o Latitude angle [pic][pic][pic][pic][pic][pic] o Observer-Sun Angles Solar altitude, zenith and azimuth angles o Geometric view of sun’s path o Daily and seasonal events o Shadows and Sundials ? Simple shadows ? Sundials o Notes on Transformation of Vector Coordinates o Summary Although many intermediate steps of derivation used to obtain the equations described in this chapter have been omitted, it is hoped that there are adequate comments between steps to encourage the student to perform the derivation, thereby enhancing understanding of the materials presented.Brief notes on the transformation of vector coordinates are included as Section 3. 5 and a summary of sign conventions for all of the angles used in this chapter is given in Table 3. 3 at the end of this chapter. Figures defining each angle and an equation to calculate it are also included.
One objective in writing this chapter has been to present adequate analytical expressions so that the solar designer is able to develop simple computer algorithms for predicting relative sun and collector positions for exact design conditions and locations. This will eliminate the need to depend on charts and tables and simplified equations. 3. Earth-Sun Angles The earth revolves around the sun every 365. 25 days in an elliptical orbit, with a mean earth-sun distance of 1. 496 x 1011 m (92. 9 x 106 miles) defined as one astronomical unit (1 AU).
This plane of this orbit is called the ecliptic plane. The earth’s orbit reaches a maximum distance from the sun, or aphelion, of 1. 52 ? 1011 m (94. 4 ? 106 miles) on about the third day of July. The minimum earth-sun distance, the perihelion, occurs on about January 2nd, when the earth is 1. 47 ? 1011 m (91. 3 ? 106 miles) from the sun.
Figure 3. 1 depicts these variations in relation to the Northern Hemisphere seasons. [pic]Figure 3. 1 The ecliptic plane showing variations in the earth-sun distance and the equinoxes and solstices. The dates and day numbers shown are for 1981 and may vary by 1 or 2 days. The earth rotates about its own polar axis, inclined to the ecliptic plane by 23. 45 degrees, in approximately 24-hour cycles. The direction in which the polar axis points is fixed in space and is aligned with the North Star (Polaris) to within about 45 minutes of arc (13 mrad).
The earth’s rotation about its polar axis produces our days and nights; the tilt of this axis relative to the ecliptic plane produces our seasons as the earth revolves about the sun. . 1. 1 Time We measure the passage of time by measuring the rotation of the earth about its axis.
The base for time (and longitude) measurement is the meridian that passes through Greenwich, England and both poles. It is known as the Prime Meridian. Today, the primary world time scale, Universal Time (previously called Greenwich Mean Time), is still measured at the Prime Meridian. This is a 24-hour time system, based on mean time, according to which the length of a day is 24 hours and midnight is 0 hours. Mean time is based on the length of an average day.
A mean second is l/86,400 of the average time between one complete transits of the sun, averaged over the entire year. In fact, the length of any one specific day, measured by the complete transit of the sun, can vary by up to 30 seconds during the year. The variable day length is due to four factors listed in order of decreasing importance (Jesperson and Fitz-Randolph, 1977): • The earth’s orbit around the sun is not a perfect circle but elliptical, so the earth travels faster when it is nearer the sun than when it is farther away. The earth’s axis is tilted to the plane containing its orbit around the sun.
• The earth spins at an irregular rate around its axis of rotation. • The earth `wobbles? on its axis. Standard Time Zones – Since it is conventional to have 12:00 noon be approximately in the middle of the day regardless of the longitude, a system of time zones has been developed. See (Blaise 2000) for an interesting story about how this unification developed. These are geographic regions, approximately 15 degrees of longitude wide, centered about a meridian along which local standard time equals mean solar time.Prior to about 1880, different cities (and even train stations) had their own time standards, most based on the sun being due south at 12:00 noon.
Time is now generally measured about standard time zone meridians. These meridians are located every 15 degrees from the Prime Meridian so that local time changes in 1-hour increments from one standard time zone meridian to the next. The standard time zone meridians east of Greenwich have times later than Greenwich time, and the meridians to the west have earlier times.Ideally, the meridians 7 [pic][pic][pic][pic][pic][pic]degrees on either side of the standard time zone meridian should define the time zone.
However, boundaries separating time zones are not meridians but politically determined borders following rivers, county, state or national boundaries, or just arbitrary paths. Countries such as Spain choose to be on `European Time (15o E) when their longitudes are well within the adjacent Standard Time Meridian (0o). Figure 3. 2 shows these time zone boundaries within the United States and gives the standard time zone meridians (called longitudes of solar time). pic][pic] Figure 3.
2 Time zone boundaries within the United States. From Jesperson and Fitz-Randolph 1977. Daylight Savings Time -To complicate matters further in trying to correlate clock time with the movement of the sun, a concept known as daylight savings time was initiated in the United States in the spring of 1918 to “save fuel and promote other economies in a country at war” (Jesperson and Fitz-Randolph, 1977). According to this concept, the standard time is advanced by 1 hour, usually from 2:00 AM on the first Sunday in April until 2:00 AM on the last Sunday in October.
Although various attempts have been made to apply this concept uniformly within the country, it is suggested that the designer check locally to ascertain the commitment to this concept at any specific solar site. Sidereal Time – So far, and for the remainder of this text, all reference to time is to mean time, a time system based on the assumption that a day (86,400 seconds) is the average interval between two successive times when a given point on the earth faces the sun. In astronomy or orbital mechanics, however, the concept of sidereal time is often used.This time system is based on the sidereal day, which is the length of time for the earth to make one complete rotation about its axis. The mean day is about 4 minutes longer than the sidereal day because the earth, during the time it is making one revolution about its axis, has moved some distance in its orbit around the sun. To be exact, the sidereal day contains 23 hours, 56 minutes, and 4. 09053 seconds of mean time.
Since, by definition, there are 86,400 sidereal seconds in a sidereal day, the sidereal second is slightly shorter than the mean solar second is.To be specific: 1 mean second = 1. 002737909 sidereal seconds.
A detailed discussion of this and other time definitions is contained in another work (Anonymous, 1981, Section B). 3. 1. 2 The Hour Angle [pic][pic][pic] [pic]To describe the earth’s rotation about its polar axis, we use the concept of the hour angle[pic][pic][pic]. As shown in Figure 3. 3, the hour angle is the angular distance between the meridian of the observer and the meridian whose plane contains the sun. The hour angle is zero at solar noon (when the sun reaches its highest point in the sky).At this time the sun is said to be ‘due south’ (or ‘due north’, in the Southern Hemisphere) since the meridian plane of the observer contains the sun.
The hour angle increases by 15 degrees every hour. [pic] Figure 3. 3 The hour angle [pic][pic][pic] . This angle is defined as the angle between the meridian parallel to sun rays and the meridian containing the observer. [pic]Solar Time – Solar time is based on the 24-hour clock, with 12:00 as the time that the sun is exactly due south.The concept of solar time is used in predicting the direction of sunrays relative to a point on the earth.
Solar time is location (longitude) dependent and is generally different from local clock time, which is defined by politically defined time zones and other approximations. Solar time is used extensively in this text to define the rotation of the earth relative to the sun. An expression to calculate the hour angle from solar time is [pic][pic][pic][pic][pic][pic] (3. 1) [pic]where ts is the solar time in hours.
EXAMPLE: When it is 3 hours after solar noon, solar time is 15:00 and the hour angle has a value of 45 degrees. When it is 2 hours and 20 minutes before solar noon, solar time is 9:40 and the hour angle is 325 degrees (or [pic][pic][pic][pic][pic][pic][pic][pic][pic]35 degrees). [pic]The difference between solar time and local clock time can approach 2 hours at various locations and times in the United States, For most solar design purposes, clock time is of little concern, and it is appropriate to present data in terms of solar time.Some situations, however, such as energy demand correlations, system performance correlations, determination of true south, and tracking algorithms require an accurate knowledge of the difference between solar time and the local clock time. Knowledge of solar time and Universal Time has traditionally been important to ship navigators. They would set their chronometers to an accurately adjusted tower clock visible as they left port. This was crucial for accurate navigation. At sea a ship’s latitude could be easily ascertained by determining the maximum altitude angle of the sun or the altitude angle of Polaris at night.
However, determining the ship’s longitude was more difficult and required that an accurate clock be carried onboard. If the correct time at Greenwich, England (or any other known location) was known, then the longitude of the ship could be found by measuring the solar time onboard the ship (through sun sightings) and subtracting from it the time at Greenwich. Since the earth rotates through 360 degrees of longitude every 24 hours, the ship then has traveled 1 degree of longitude away from the Prime Meridian (which passes through Greenwich) for every 4 minutes of time difference.An interesting story about developing accurate longitude measurements may be found in Sobel, 1999. Equation of Time – The difference between mean solar time and true solar time on a given date is shown in Figure 3. 4. This difference is called the equation of time (EOT). Since solar time is based on the sun being due south at 12:00 noon on any specific day, the accumulated difference between mean solar time and true solar time can approach 17 minutes either ahead of or behind the mean, with an annual cycle.
The level of accuracy required in determining the equation of time will depend on hether the designer is doing system performance or developing tracking equations. An approximation for calculating the equation of time in minutes is given by Woolf (1968) and is accurate to within about 30 seconds during daylight hours. [pic][pic][pic][pic][pic][pic](3. 2) [pic]where the angle x is defined as a function of the day number N [pic][pic][pic][pic][pic][pic][pic][pic][pic] (3. 3) [pic]with the day number, N being the number of days since January 1. Table 3.
1 has been prepared as an aid in rapid determination of values of N from calendar dates. Table 3. 1 Date-to-Day Number Conversion Month |Day Number, N |Notes | |January |d | | |February |d + 31 | | |March |d + 59 |Add 1 if leap year | |April |d + 90 |Add 1 if leap year | |May |d + 120 |Add 1 if leap year | |June |d + 151 |Add 1 if leap year | |July |d + 181 |Add 1 if leap year | |August |d + 212 |Add 1 if leap year | |September |d + 243 |Add 1 if leap year | |October |d + 273 |Add 1 if leap year | |November |d + 304 |Add 1 if leap year | |December |d + 334 |Add 1 if leap year | |Days of Special Solar Interest | |Solar Event |Date |Day Number, N | |Vernal equinox |March 21 |80 | |Summer solstice |June 21 |172 | |Autumnal equinox |September 23 |266 | |Winter solstice |December 21 |355 | |NOTES: | |d is the day of the month | |Leap years are 2000, 2004, 2008 etc. | |Solstice and equinox dates may vary by a day or two. Also, add 1 to the solstice and | |equinox day number for leap years. | [pic] Figure 3.
4 The equation of time (EOT).This is the difference between the local apparent solar time and the local mean solar time. EXAMPLE: February 11 is the 42nd day of the year, therefore N = 42 and x is equal to 40. 41 degrees, and the equation of time as calculated above is [pic][pic][pic][pic][pic][pic][pic][pic][pic]14. 35 minutes. This compares with a very accurately calculated value of -14. 29 minutes reported elsewhere (Anonymous, 198l). This means that on this date, there is a difference between the mean time and the solar time of a little over 14 minutes or that the sun is “slow” relative to the clock by that amount.
[pic][pic]To satisfy the control needs of concentrating collectors, a more accurate determination of the hour angle is often needed.An approximation of the equation of time claimed to have an average error of 0. 63 seconds and a maximum absolute error of 2. 0 seconds is presented below as Equation (3. 4) taken from Lamm (1981).
The resulting value is in minutes and is positive when the apparent solar time is ahead of mean solar time and negative when the apparent solar time is behind the mean solar time: [pic][pic][pic][pic][pic][pic] (3. 4) [pic]Here n is the number of days into a leap year cycle with n = 1 being January 1 of each leap year, and n =1461 corresponding to December 31 of the 4th year of the leap year cycle. The coefficients Ak and Bk are given in Table 3. 2 below.Arguments for the cosine and sine functions are in degrees. Table 3. 2 Coefficients for Equation (3. 4) |k |Ak (hr) |Bk (hr) | |0 |2.
0870 ? 10-4 |0 | |1 |9. 2869 ? 10-3 |[pic][pic][pic][pic][pic][p| | | |ic][pic][pic][pic]1. 2229 ? | | | |10-1 | |2 |[pic][pic][pic][pic][pic][pic|[pic][pic][pic][pic][pic][p| | |][pic][pic][pic]5. 2258 ? 10-2|ic][pic][pic][pic]1.
5698 ? | | |10-1 | |3 |[pic][pic][pic][pic][pic][pic|[pic][pic][pic][pic][pic][p| | |][pic][pic][pic]1. 3077 ? l0-3|ic][pic][pic][pic]5. 1 602 ? | | | |10-3 | |4 |[pic][pic][pic][pic][pic][pic|[pic][pic][pic][pic][pic][p| | |][pic][pic][pic]2.
1867 ? l0-3|ic][pic][pic][pic]2. 9823 ? | | | |10-3 | |5 |[pic][pic][pic][pic][pic][pic|[pic][pic][pic][pic][pic][p| | |][pic][pic][pic]1. 5100 ? 10-4|ic][pic][pic][pic]2. 3463 ? | | |10-4 | [pic][pic][pic][pic][pic][pic][pic][pic][pic]Time Conversion – The conversion between solar time and clock time requires knowledge of the location, the day of the year, and the local standards to which local clocks are set.
Conversion between solar time, ts and local clock time (LCT) (in 24-hour rather than AM/ PM format) takes the form [pic][pic][pic][pic][pic][pic] (3. 5) [pic]where EOT is the equation of time in minutes and LC is a longitude correction defined as follows: [pic][pic][pic][pic][pic][pic] (3. 6) [pic]and the parameter D in Equation (3. ) is equal to 1 (hour) if the location is in a region where daylight savings time is currently in effect, or zero otherwise. EXAMPLE: Let us find the clock time for solar noon at a location in Los Angeles, having a longitude of 118. 3 degrees on February 11. Since Los Angeles is on Pacific Standard Time and not on daylight savings time on this date, the local clock time will be: [pic][pic][pic][pic][pic][pic] [pic]3. 1.
3 The Declination Angle [pic][pic][pic] [pic]The plane that includes the earth’s equator is called the equatorial plane. If a line is drawn between the center of the earth and the sun, the angle between this line and the earth’s equatorial plane is called the declination angle[pic][pic][pic][pic], as depicted in Figure 3. 5.At the time of year when the northern part of the earth’s rotational axis is inclined toward the sun, the earth’s equatorial plane is inclined 23. 45 degrees to the earth-sun line.
At this time (about June 21), we observe that the noontime sun is at its highest point in the sky and the declination angle [pic][pic][pic][pic][pic][pic]= +23. 45 degrees. We call this condition the summer solstice, and it marks the beginning of summer in the Northern Hemisphere. [pic][pic]As the earth continues its yearly orbit about the sun, a point is reached about 3 months later where a line from the earth to the sun lies on the equatorial plane. At this point an observer on the equator would observe that the sun was directly overhead at noontime.This condition is called an equinox since anywhere on the earth, the time during which the sun is visible (daytime) is exactly 12 hours and the time when it is not visible (nighttime) is 12 hours.
There are two such conditions during a year; the autumnal equinox on about September 23, marking the start of the fall; and the vernal equinox on about March 22, marking the beginning of spring. At the equinoxes, the declination angle [pic][pic][pic][pic][pic][pic]is zero. [pic][pic] Figure 3. 5 The declination angle[pic][pic][pic][pic][pic][pic]. The earth is shown in the summer solstice position when [pic][pic][pic][pic][pic][pic]= +23. 45 degrees.Note the definition of the tropics as the intersection of the earth-sun line with the surface of the earth at the solstices and the definition of the Arctic and Antarctic circles by extreme parallel sun rays.
[pic][pic]The winter solstice occurs on about December 22 and marks the point where the equatorial plane is tilted relative to the earth-sun line such that the northern hemisphere is tilted away from the sun. We say that the noontime sun is at its “lowest point” in the sky, meaning that the declination angle is at its most negative value (i. e. , [pic][pic][pic][pic][pic][pic]= -23. 45 degrees).
By convention, winter declination angles are negative. pic]Accurate knowledge of the declination angle is important in navigation and astronomy. Very accurate values are published annually in tabulated form in an ephemeris; an example being (Anonymous, 198l). For most solar design purposes, however, an approximation accurate to within about 1 degree is adequate. One such approximation for the declination angle is [pic][pic][pic][pic][pic][pic] (3. 7) [pic]where the argument of the cosine here is in degrees and N is the day number defined for Equation (3.
3) The annual variation of the declination angle is shown in Figure 3. 5. 3. 1.
4 Latitude Angle [pic][pic][pic][pic][pic][pic] pic]The latitude angle [pic][pic][pic][pic][pic][pic]is the angle between a line drawn from a point on the earth’s surface to the center of the earth, and the earth’s equatorial plane. The intersection of the equatorial plane with the surface of the earth forms the equator and is designated as 0 degrees latitude. The earth’s axis of rotation intersects the earth’s surface at 90 degrees latitude (North Pole) and -90 degrees latitude (South Pole). Any location on the surface of the earth then can be defined by the intersection of a longitude angle and a latitude angle. [pic]Other latitude angles of interest are the Tropic of Cancer (+23.
45 degrees latitude) and the Tropic of Capricorn (- 23. 45 degrees latitude).These represent the maximum tilts of the north and south poles toward the sun.
The other two latitudes of interest are the Arctic circle (66. 55 degrees latitude) and Antarctic circle (-66. 5 degrees latitude) representing the intersection of a perpendicular to the earth-sun line when the south and north poles are at their maximum tilts toward the sun.
As will be seen below, the tropics represent the highest latitudes where the sun is directly overhead at solar noon, and the Arctic and Antarctic circles, the lowest latitudes where there are 24 hours of daylight or darkness. All of these events occur at either the summer or winter solstices. 3.
2 Observer-Sun AnglesWhen we observe the sun from an arbitrary position on the earth, we are interested in defining the sun position relative to a coordinate system based at the point of observation, not at the center of the earth. The conventional earth-surface based coordinates are a vertical line (straight up) and a horizontal plane containing a north-south line and an east-west line. The position of the sun relative to these coordinates can be described by two angles; the solar altitude angle and the solar zenith angle defined below.
Since the sun appears not as a point in the sky, but as a disc of finite size, all angles discussed in the following sections are measured to the center of that disc, that is, relative to the “central ray” from the sun. 3. 2.
1 Solar Altitude, Zenith, and Azimuth AnglesThe solar altitude angle [pic][pic][pic][pic][pic][pic]is defined as the angle between the central ray from the sun, and a horizontal plane containing the observer, as shown in Figure 3. 6. As an alternative, the sun’s altitude may be described in terms of the solar zenith angle [pic][pic][pic][pic][pic][pic]which is simply the complement of the solar altitude angle or [pic][pic][pic][pic][pic][pic][pic][pic] (3. 8) [pic]The other angle defining the position of the sun is the solar azimuth angle (A).
It is the angle, measured clockwise on the horizontal plane, from the north-pointing coordinate axis to the projection of the sun’s central ray. [pic] Figure 3. Earth surface coordinate system for observer at Q showing the solar azimuth angle ? , the solar altitude angle [pic][pic][pic][pic][pic][pic]and the solar zenith angle [pic][pic][pic][pic][pic][pic]for a central sun ray along direction vector S. Also shown are unit vectors i, j, k along their respective axes.
[pic][pic]The reader should be warned that there are other conventions for the solar azimuth angle in use in the solar literature. One of the more common conventions is to measure the azimuth angle from the south-pointing coordinate rather than from the north-pointing coordinate. Another is to consider the counterclockwise direction positive rather than clockwise.The information in Table 3. 3 at the end of this chapter will be an aid in recognizing these differences when necessary. It is of the greatest importance in solar energy systems design, to be able to calculate the solar altitude and azimuth angles at any time for any location on the earth. This can be done using the three angles defined in Section 3. 1 above; latitude [pic][pic][pic][pic][pic][pic], hour angle [pic][pic][pic][pic][pic][pic], and declination [pic][pic][pic][pic][pic][pic].
If the reader is not interested in the details of this derivation, they are invited to skip directly to the results; Equations (3. 17), (3. 18) and (3. 19).
pic][pic][pic]For this derivation, we will define a sun-pointing vector at the surface of the earth and then mathematically translate it to the center of the earth with a different coordinate system. Using Figure 3. 6 as a guide, define a unit direction vector S pointing toward the sun from the observer location Q: [pic][pic][pic][pic][pic][pic] (3. 9) [pic]where i, j, and k are unit vectors along the z, e, and n axes respectively. The direction cosines of S relative to the z, e, and n axes are Sz, Se and Sn, respectively. These may be written in terms of solar altitude and azimuth as [pic][pic][pic][pic][pic][pic] (3. 10) [pic]Similarly, a direction vector pointing to the sun can be described at the center of the earth as shown in Figure 3. 7.
If the origin of a new set of coordinates is defined at the earth’s center, the m axis can be a line from the origin intersecting the equator at the point where the meridian of the observer at Q crosses. The e axis is perpendicular to the m axis and is also in the equatorial plane. The third orthogonal axis p may then be aligned with the earth’s axis of rotation.
A new direction vector S? pointing to the sun may be described in terms of its direction cosines S? m , S’e and S’p relative to the m, e, and p axes, respectively. Writing these in terms of the declination and hour angles, we have [pic][pic][pic][pic][pic][pic] (3. 11) [pic]Note that S? e is negative in the quadrant shown in Figure 3. 7. [pic] Figure 3. Earth center coordinate system for the sun ray direction vector S defined in terms of hour angle [pic][pic][pic][pic][pic][pic]and the declination angle [pic][pic][pic][pic][pic][pic]. [pic][pic]These two sets of coordinates are interrelated by a rotation about the e axis through the latitude angle [pic][pic][pic][pic][pic][pic]and translation along the earth radius QC. We will neglect the translation along the earth’s radius since this is about 1 / 23,525 of the distance from the earth to the sun, and thus the difference between the direction vectors S and S? is negligible.
The rotation from the m, e, p coordinates to the z, e, n coordinates, about the e axis is depicted in Figure 3. 8. Both sets of coordinates are summarized in Figure 3. 9.Note that this rotation about the e axis is in the negative sense based on the right-hand rule. In matrix notation, this takes the form [pic][pic][pic][pic][pic][pic][pic] (3.
12) [pic][pic] Figure 3. 8 Earth surface coordinates after translation from the observer at Q to the earth center C. [pic] Figure 3. 9 Composite view of Figures 3. 6, 3. 7 and 3. 8 showing parallel sun ray vectors S and S’ relative to the earth surface and the earth center coordinates.
Solving, we have [pic][pic][pic][pic][pic][pic] (3. 13) [pic]Substituting Equations (3. 10) and (3. 1)(3. 11) for the direction cosine gives us our three important results [pic][pic][pic][pic][pic][pic] (3.
4) [pic][pic][pic][pic][pic][pic][pic] (3. 15) [pic][pic][pic][pic][pic][pic][pic] (3. 16) [pic]Equation (3. 14) is an expression for the solar altitude angle in terms of the observer’s latitude (location), the hour angle (time), and the sun’s declination (date). Solving for the solar altitude angle [pic][pic][pic][pic][pic][pic], we have [pic][pic][pic][pic][pic][pic][pic] (3. 17) [pic]Two equivalent expressions result for the solar azimuth angle (A) from either Equation (3. 15) or (3. 16).
To reduce the number of variables, we could substitute Equation (3. 14) into either Equation (3. 15) or (3. 6); however, this substitution results in additional terms and is often omitted to enhance computational speed in computer codes. The solar azimuth angle can be in any of the four trigonometric quadrants depending on location, time of day, and the season. Since the arc sine and arc cosine functions have two possible quadrants for their result, both Equations (3. 15) and (3. 16) require a test to ascertain the proper quadrant.
No such test is required for the solar altitude angle, since this angle exists in only one quadrant. The appropriate procedure for solving Equation (3. 15) is to test the result to determine whether the time is before or after solar noon. For Equation (3.
5), a test must be made to determine whether the solar azimuth is north or south of the east-west line. Two methods for calculating the solar azimuth (A), including the appropriate tests, are given by the following equations. Again, these are written for the azimuth angle sign convention used in this text, that is, that the solar azimuth angle is measured from due north in a clockwise direction, as with compass directions.
Solving Equation (3. 15) the untested result, A’ then becomes [pic][pic][pic][pic][pic][pic] (3. 18) [pic]A graphical description of this test will follow in the next section. Solving Equation (3. 16), the untested result, A” becomes pic][pic][pic][pic][pic][pic] (3. 19) [pic]In summary, we now have equations for both the sun’s altitude angle and azimuth angle written in terms of the latitude, declination and hour angles. This now permits us to calculate the sun’s position in the sky, as a function of date, time and location (N, [pic][pic][pic][pic][pic][pic],[pic][pic][pic][pic][pic][pic]). [pic][pic]EXAMPLE: For a site in Miami, Florida (25 degrees, 48 minutes north latitude/ 80 degrees, 16 minutes west longitude) at 10:00 AM solar time on August 1 (not a leap year), find the sun’s altitude, zenith and azimuth angles….. For these conditions, the declination angle is calculated to be 17. 0 degrees, the hour angle -30 degrees and the sun’s altitude angle is then 61. 13 degrees, the zenith angle 28. 87 degrees and the azimuth angle 99. 77 degrees. 3. 2. 2 A Geometric View of Sun’s Path The path of the sun across the sky can be viewed as being on a disc displaced from the observer. This “geometric” view of the sun’s path can be helpful in visualizing sun movements and in deriving expressions for testing the sun angles as needed for Equation (3. 18) to ascertain whether the sun is in the northern sky. The sun may be viewed as traveling about a disc having a radius R at a constant rate of 15 degrees per hour. As shown in Figure 3. 0, the center of this disc appears at different seasonal locations along the polar axis, which passes through the observer at Q and is inclined to the horizon by the latitude angle [pic][pic][pic][pic][pic][pic]pointing toward the North Star (Polaris). [pic][pic] Figure 3. 10 A geometric view of the sun’s path as seen by an observer at Q. Each disc has radius R. The center of the disc is coincident with the observer Q at the equinoxes and is displaced from the observer by a distance of [pic][pic][pic][pic][pic][pic]at other times of the year. The extremes of this travel are at the solstices when the disc is displaced by ± 0. 424 R along the polar axis. It can be seen that in the winter, much of the disc is “submerged” below the horizon, giving rise to fewer hours of daylight and low sun elevations as viewed from Q. pic]At the equinoxes, the sun rises exactly due east at exactly 6:00 AM (solar time) and appears to the observer to travel at a constant rate across the sky along a path inclined from the vertical by the local latitude angle. Exactly one-half of the disc is above the horizon, giving the day length as 12 hours. At noon, the observer notes that the solar zenith angle is the same as the local latitude. The sun sets at exactly 6:00 PM, at a solar azimuth angle of exactly 270 degrees or due west. In the summer, the center of the disc is above the observer, giving rise to more hours of daylight and higher solar altitude angles, with the sun appearing in the northern part of the sky in the mornings and afternoons.Since the inclination of the polar axis varies with latitude it can be visualized that there are some latitudes where the summer solstice disc is completely above the horizon surface. It can be shown that this occurs for latitudes greater than 66. 55 degrees, that is, above the Arctic Circle. At the equator, the polar axis is horizontal and exactly half of any disc appears above the horizon surface, which means that the length of day and night is 12 hours throughout the year. A test to determine whether the sun is in the northern part of the sky may be developed by use of this geometry. Figure 3. 11 is a side view of the sun’s disc looking from the east. [pic]Figure 3. 11 Side view of sun path disc during the summer when the disc center Y is above the observer at Q. In the summer the sun path disc of radius R has its center Y displaced above the observer Q. Point X is defined by a perpendicular from Q. In the n – z plane, the projection of the position S onto the line containing X and Y will be [pic][pic][pic][pic][pic][pic]where [pic][pic][pic][pic][pic][pic]is the hour angle. The appropriate test for the sun being in the northern sky is then [pic][pic][pic][pic][pic][pic][pic][pic] (3. 20) [pic]The distance XY can be found by geometry arguments. Substituting into Equation (3. 0), we have [pic][pic][pic][pic][pic][pic][pic] (3. 21) [pic]This is the test applied to Equation (3. 18) to ensure that computed solar azimuth angles are in the proper quadrant. 3. 2. 3 Daily and Seasonal Events Often the solar designer will want to predict the time and location of sunrise and sunset, the length of day, and the maximum solar altitude. Expressions for these are easily obtained by substitutions into expressions developed in Section 3. 2. l. The hour angle for sunset (and sunrise) may be obtained from Equation (3. 17) by substituting the condition that the solar altitude at sunset equals the angle to the horizon.If the local horizon is flat, the solar altitude is zero at sunset and the hour angle at sunset[pic][pic][pic][pic][pic][pic]becomes [pic][pic][pic][pic][pic][pic][pic] (3. 22) [pic]The above two tests relate only to latitudes beyond ± 66. 55 degrees, i. e. above the Arctic Circle or below the Antarctic Circle. [pic][pic][pic][pic][pic][pic][pic][pic][pic][pic] [pic]If the hour angle at sunset is known, this may be substituted into Equation (3. 18) or (3. 19) to ascertain the solar azimuth at sunrise or sunset. The hours of daylight, sometimes of interest to the solar designer, may be calculated as [pic][pic][pic][pic][pic][pic] (3. 23) [pic]where ? s is in degrees.It is of interest to note here that although the hours of daylight vary from month to month except at the equator (where [pic][pic][pic][pic][pic][pic]), there are always 4,380 hours of daylight in a year (non leap year) at any location on the earth. [pic]Another limit that may be obtained is the maximum and minimum noontime solar altitude angle. Substitution of a value of [pic][pic][pic][pic][pic][pic]into Equation (3. 17) gives [pic][pic][pic][pic][pic][pic][pic] (3. 24) [pic]where [pic][pic][pic][pic][pic][pic]denotes the absolute value of this difference. An interpretation of Equation (3. 24) shows that at solar noon, the solar zenith angle (the complement of the solar altitude angle) is equal to the latitude angle at the equinoxes and varies by ±23. 5 degrees from summer solstice to winter solstice. [pic]EXAMPLE: At a latitude of 35 degrees on the summer solstice (June 21), find the solar time of sunrise and sunset, the hours of daylight, the maximum solar altitude and the compass direction of the sun at sunrise and sunset….. On the summer solstice, the declination angle is +23. 45 degrees, giving an hour angle at sunset of 107. 68 degrees. Therefore, the time of sunrise is 4:49:17 and of sunset, 19:10:43. There are 14. 36 hours of daylight that day, and the sun reaches a maximum altitude angle of 78. 45 degrees. The sun rises at an azimuth angle of 60. 94 degrees (north of east) and sets at an azimuth angle of 299. 6 degrees (north of west).


The company is a bit stealthy right now. But it's proposing OpenFlow, the open source-based programmable control plane protocol, as a foundation for building enterprise and service provider networks, especially those with large data centers.
The company is putting the finishing touches on an OpenFlow controller, according to blogger Greg Ferro at Etherealmind.
OpenFlow is a 6-year-old project initiated by Stanford University and the University of California at Berkeley. Big Switch Networks, based in Palo Alto, is led by Guido Appenzeller, a former a Stanford assistant professor.
Ex-Cisco executive Mike Volpi is on the company's board.
OpenFlow is designed to separate the control function of switches from the switch hardware and forwarding function so that users can program traffic patterns in a network of multivendor switches and routers. Currently, control plane capabilities are tightly tied to specific vendor's hardware and feature limited, if any, programmability.
OpenFlow might even help alleviate the need for users to write customized scripting software to orchestrate traffic among multivendor routers and switches.
An industry group was just formed to promote OpenFlow and software-defined networking. The Open Network Foundation includes Google, Yahoo, Verizon, Cisco and many other industry luminaries.
In addition to Big Switch Networks, OpenFlow is available from switch vendor Pica8. Several major vendors are expected to soon announce plans to support it and the Interop conference in Las Vegas next month is expected to have an OpenFlow demonstration.
Read more about lan and wan in Network World's LAN & WAN section.


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Courses from Egypt's Al-Azhar University Heading to Denmark
by David J. Rusin • Apr 27, 2008 at 12:50 pm
Danish Muslims will no longer have to visit Cairo to immerse their minds in the curriculum of Al-Azhar University, frequently cited as the center of learning in Sunni Islam. The classes are coming to them:
The new venture intends to "confront misconceptions about Islam and explain the true Islam to the European society." One imagines this to be yet another response to the row over cartoons of Mohammed published by a Danish newspaper in September 2005.
But what kind of education will these students receive? For insight into the worldview that characterizes Al-Azhar, one must begin with Muhammad Sayyed Tantawi, the university's grand sheikh. In the 1970s Tantawi penned a 700-page tome that rationalizes Muslim Jew-hatred. More recently, he has praised suicide bombings of civilians and called for the beheading of anyone who insults the holy books or prophets of monotheistic faiths.
As for the curriculum of Al-Azhar, one former student — who was expelled and arrested for his publications on a reformist website — has written that the university promotes "things that contradict reason and incite to violence against people of other beliefs." A liberal professor at Cairo University has likewise criticized the school for employing the texts of "extremist sheikhs":
Which brings us to an even more troubling question: will they teach this same way of thinking to Muslims in Denmark?


text:
Since its launch in 2013, the LVMH Prize has continued to offer support to young fashion designers and help turn their dreams into a reality. Every year, the group selects a young designer and three fashion school graduates to claim the prestigious prize.
Now that applications are open to enthusiasts around the world (the application deadline is on February 4, 2018), the announcement of the finalists in March will be selected by a panel of A-list industry professionals.
Already on the list, the jury includes Dior‘s Maria Grazia Chiuri, Kenzo and Monse‘s Carol Lim and Humberto Leon, Louis Vuitton‘s Nicolas Ghesquière, Marc Jacobs, Chanel‘s Karl Lagerfeld and J.W.Anderson.
This year, two new designers have been added to the exceptional jury panel. Expect to see Clare Waight Keller — who joined Givenchy as their first female chief — and Berluti‘s Haider Ackermann added to the lineup. Also, Sidney Toledano, the Chairman and Chief Executive Officer of the Fashion Group, was named as the third addition to the jury list.
The 2018 LVMH Prize semi-finals will be announced on March 1 and 2, during Paris Fashion Week. In other fashion news, find out which designer just dropped out of New York Fashion Week.

domain: design