|Publication number||US3735399 A|
|Publication date||May 22, 1973|
|Filing date||Nov 23, 1971|
|Priority date||Nov 23, 1971|
|Also published as||US3735400|
|Publication number||US 3735399 A, US 3735399A, US-A-3735399, US3735399 A, US3735399A|
|Inventors||Holt F, Sletten C|
|Original Assignee||Us Air Force|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (1), Referenced by (21), Classifications (6)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent Sletten et al.
METHOD FOR IMPROVING THE TARGET POSITION VECTOR ACCURACY OF AN AMTI RADAR inventors: Carlyle J. Sletten, Acton; F. Sheppard Holt, Winchester, both of Mass.
Assignee: The United States of America as represented by the Secretary of the Air Force, Washington, DC.
Filed: Nov. 23, 1971 Appl. No.: 201,581
 References Cited UNITED STATES PATENTS 3,161,873 12/1964 Hollingsworth ,.343/7.7
Primary ExaminerT. H. Tubbesing Attorney-Harry A. Herbert, Jr. and Willard R. Matthews, Jr.
[57} ABSTRACT Target bearing angle accuracy is improved through increased time on target followed by processing including averaging and synthetic aperture techniques. The course target position vector provided by an AMTI interferometer type radar is analytically extended to its US. Cl ..343/7.7, 343/5 CM point of minimum range. The target range, bearing,
and velocity values for the point are adjusted to incor- Int. Cl. ..G01s 9/42 porate a mmlmlzed error l derived from sured and calculated target position data for a given interval of time. The adjusted values are used to Field of Search ..343/5 CM, 7.7, 17.1 R establish a more accurate target position vector.
1 Claim, 2 Drawing Figures 6 macmrr 20 I9 w 1 amsmui VELOCITY n annex Gm- DELAYS CONTROLLED F RE TR AG (F) "M (1) MR n MQTRIX Movmc. CLu'r'TER LOCAL Renee *cpmcge zg cscltm-rn '5 6 ATS Cunmuns Fl-B S 17 l RANGE 6 15 11+ 1 l RNTENNA VELOC -r-r A To TRACKER J \SoLn'roR bovrLiil FIXED TR 5 TRRJZCTORY RMPMFIER MxER flNGULRfl m' flflsE FREGUEW-Y DELAY AMP SWITCH PREDrc-rol 3511mm JNVERTER FILTERS 1 R s E Pu L551! 2, Movws CLUT'T'ER a we: fi-CQNCILLER 2y. GATE CunwznsB-CT filunumz I2 I F V c VELocwrY novvcck 1R5 TR L s Cou-riuu.zn Fnfiqum 6149mm MWER n p s CH A e C) M (#1 hfwl'r'cH FILTERS M V w a-rn 1): 20 19 u,
METHOD FOR IMPROVING THE TARGET POSITION VECTOR ACCURACY OF AN AMTI RADAR BACKGROUND OF THE INVENTION This invention relates to airborne moving target indicating radar systems, and in particular to means for improving the accuracy of target bearing information derived therefrom.
An AMTI radar system typical of the type to which the present invention applies is disclosed in our copending U. S. patent application Ser. No. 201,5 82 entitled, AMTI Radar Clutter Cancelling Method and Apparatus, filed on even date herewith. Such a system employs synthetic aperture techniques and utilizes multiple antennas disposed along the flight velocity vector of the observer aircraft. The target bearing data provided by such a system is basically the output of an interferometer whose accuracy is in the order of 1 to 5. With such a system bearing accuracy is maximum at minimum target range and diminishes as distance between aircraft and headings change. For many applications such course bearing information is grossly inadequate. There currently exists therefore the need for improving the accuracy of AMTI radar bearing information whereby target position vectors can be reliably determined and projected. The present invention is directed toward satisfying such a need.
SUMMARY OF THE INVENTION The observer aircraft flight velocity vector and the target flight velocity vector as described in the interferometer of the AMTI radar are initially extended to a minimum range condition (maximum bearing accuracy condition). Over an interval of time a series of position measurements are taken at times 1 t t The target position for the time t,, is calculated on the basis of the range, bearing and velocity values as extended to the minimum range condition. An error function is derived from the difference between the calculated target position at t and the actual measured target position at t The error function is minimized with respect to the minimum range condition parameters and such minimum range condition parameters are subsequently adjusted to incorporate the minimized error function. Target bearing is then calculated using the adjusted minimum range condition parameters.
It is the principal object of the invention to provide a new and improved method for improving the target position vector of an AMTI radar.
Such object, together with other features and advantages of the invention, will become more readily apparent from the following detailed description when taken in conjunction with the illustrated embodiments in the accompanying drawings.
DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of am AMTI radar system of the type comprehended by the invention; and
FIG. 2 illustrates relative observer aircraft and target flight velocity vectors and other relevant parameters necessary to resolving target position vector problems by the method of the invention.
DETAILED DESCRIPTION OF THE PREFERRED METHOD Referring now to FIG. 1, there is illustrated thereby in block diagram an AMTI radar system of the type to which the method of the present invention can advantageously be applied. Antennas A, B and C are positioned on the observer aircraft in a line coincident with its velocity vector V a distance S apart. TR switches l 1 permit transmitting and receiving on all antennas although in practice transmitter 10 would normally only transmit through antenna B. The received doppler echo signals are amplified by preamplifiers l2 and mixed with the output of local oscillator 13 in mixer 14. After further amplification by amplifiers 15 the signals are filtered into narrow band channels by doppler filters 16. Antenna B is provided with a fixed delay 17 to permit phase coincidence of the signals on all antennas (both leading and lagging). Doppler frequency signals in the clutter frequency spectrum are delayed on antennas A and C by means of delay lines 19. Velocity controlled switch matrixes 18 connect the narrow band channels to appropriate delays in response to aircraft ground speed. The doppler echo signals in the clutter frequency spectrum from all antennas are thus made phase coincident. The signals from antenna B are phase inverted by phase inverter 21. This phase inverted signal is then summed with the outputs of antennas A and C in clutter cancellers 22. Signals from moving targets are not cancelled and are fed to moving range gate 23. The outputs of range gates 23 are integrated by integrators 24 to improve system gain. The outputs of integrators 24 are compared by phase comparator 25 to ascertain target bearing information. The method of the present invention improves the accuracy of such bearing information in the manner hereinafter described.
The observations on distant or weak echoes require a second or so for detection (integration in moving range bins) and then the signals gathered simultaneously by interferometer AB-BC are phase compared and presented to on-board computer logic for location of targets, their presentations, and prediction of future target trajectory. The observed data are essentially corrected for the aircraft radar platform motion, and analytic rendering of the information as time progresses permits reviewing of the target over a long base line. This horizontal base line allows improved angle determination.
The observational data includes relative time, range, range difference, doppler frequency shift (leading to radial range rate), observer (radar platform) velocity, and bearing angle. Relative time, range doppler frequency shift, and observer velocity can be accurately determined while bearing angle can only be coarsely determined to within 1 5. Range differencescan be determined to very high accuracy (-A/50). Bearing angle accuracy can be improved in accordance with the method of the invention through increased time on target followed by processing including averaging and synthetic aperture techniques. The remarkably good bearing accuracy obtained in the fixed target case with state of the art fixed target detection systems depends on accurate determination of range differences by an observer whose motion over an extended path is accurately known relative to the target. In the moving target case with the system presented here the motion of the observer relative to the target is known only through the coarse (AB-BC interferometer) bearing data. However, the accuracy of the determination of this path can be improved by averaging or by least mean square techniques. For the fixed target system the highest angular accuracy for a given length of observation interval occurs when the observer path is nearly normal to the radial vector from the fixed target to the observer. For the moving target case the highest accuracy for a given length of observation interval occurs when the path of the observer relative to the target is nearly normal to the radial vector from the target to the observer. For both types of targets these optimum conditions are associated with low doppler shift but high rate of doppler shift. They are also associated with minimum target range and maximum rate of change of true bearing angle. Thus judicious choice of the observer ground path can lead to an optimum or nearly optimum observer path relative to the target.
A least mean square method for improving angular accuracy in the moving target case proceeds as follows:
Assume that an observer (the radar aircraft) and a target are both moving with uniform velocity in a horizontal plane. lf VI, is the observer radar velocity relative to the ground and 7 is the target velocity relative to the ground, then 72,, the velocity of the target relative to the observer, is also uniform. If 7:, is accurately known then calculation of VI, will yield since Let xy be a rectangular coordinate system moving in the horizontal plane with origin fixed at the observer as illustrated in FIG. 2. Then the target position vector relative to 0 will be 7=z +2, (tt,,) where t is time, 7; is the target position vector to the point on the target path closest to O and t,, is the time at which r =7;
r,, magnitude of F;
0,, angle of 7,, measured positive counter clockwise relative to the x axis,
and v,, magnitude of 7:, with sign affixed positive if target motion about 0 is counterclockwise and negative if target motion is clockwise. The vectors F: and VI, can then be written i r,, r,, cos 0,, H-r sin 0,;
0 4 v,, v,,s1n 0,, H-v cos 0,,
A A u where i and j are the conventional umt vectors in the x and y directions respectively.
The target position vector is then a function of the four parameters r,,, 0,,, v,,, and t,, as follows:
+ [r,, sin 0,, (t t,,) v,, cos 0,, ]j
Let the position of a target be observed to within a known accuracy at a series of times t 2,, t I Assuming the target to have uniform velocity, we wish to determine r,,, 0,,, v,,t,, such that the target motion associated with the choice of the parameters fits the observed data most closely in a least mean square sense. Let the error function E be defined as A where p,, x l y,, j is the observed target position at t t,, and r,, is the target position calculated at z t,, on
the basis of general target parameters, r 0,,,V,, and t,,. The procedure is to minimize E relative to these parameters.
Necessary conditions for minimizing E are SE/Br 8E/80 8E/u5v 6E/8t 0 These conditions lead to the equations:
[56,, cos 0 y sin 0 -11,] =0
[I sin 0 y cos 00+ no) ol= X sin 0,, Y cos 0,, (T Nt,,)v,,
where N N X z I X.=E t r 11:1 n=l N N Y E 1/", 1 2 n?! 1 =1 N N 2 n, r=2 n i n=l Also sin 0,, cos 0,, 1
implies o) o) 0 X +X Substituting (5) and (6) into (3) yields 5 Substituting (1) into (2) yields +22%) Sin 0+ -2 +21%) 005 o= 0 o 0 and substituting (5) and (6) into (9) yields rr+rw--ar rzow w Equations (7), (8) and 10) can be solved for r,,, t and v, as follows:
r, A B /(BN) (CN AT) While the invention has been described in terms of one presently preferred method, it is understood that the words which have been used are words of description rather than words of limitation and that changes with the purview of the appended claims may be made without departing from the scope and spirit of the invention in its broader aspects. What is claimed is:
1. In conjunction with an observer aircraft equipped with an AMTI radar system capable of providing target range and course interferometer bean'ng data, the method of deriving a target position vector of improved accuracy comprising the steps of assigning values for the parameters of minimum range, bearing at minimum range, target velocity, and time at which the target is at minimum range for the true target path,
analytically extending a course target velocity vector obtained from the radar system output to a minimum range condition,
taking a series of target position measurements at times t t calculating on the basis of the extended range, bearing and velocity values at minimum range condition the target position at time t,,, deriving an error function from the difference between the final measured target position values and the calculated target position values, minimizing said error functions for range bearing and velocity values at the minimum range condition, adjusting the extended range, bearing and velocity values for minimum range conditions to incorporate said minimized error functions, and calculating a target position vector from said adjusting values.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3161873 *||Nov 3, 1961||Dec 15, 1964||Hollingsworth Lowell M||Moving target indication method and system|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US3993994 *||Jun 27, 1975||Nov 23, 1976||The United States Of America As Represented By The Secretary Of The Air Force||Adaptive clutter cancellation for synthetic aperture AMTI radar|
|US4086590 *||Jan 21, 1977||Apr 25, 1978||The United States Of America As Represented By The Secretary Of The Air Force||Method and apparatus for improving the slowly moving target detection capability of an AMTI synthetic aperture radar|
|US4093950 *||May 16, 1977||Jun 6, 1978||The United States Of America As Represented By The Secretary Of The Navy||Motion-compensation arrangements for MTI radars|
|US4093951 *||May 16, 1977||Jun 6, 1978||The United States Of America As Represented By The Secretary Of The Navy||Compensation for simultaneous platform motion and antenna scanning in MTI radars|
|US4546354 *||Jun 17, 1982||Oct 8, 1985||Grumman Aerospace Corporation||Range/azimuth ship imaging for ordnance control|
|US4549184 *||Apr 30, 1982||Oct 22, 1985||Grumman Aerospace Corporation||Moving target ordnance control|
|US4551724 *||Feb 10, 1983||Nov 5, 1985||The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration||Method and apparatus for contour mapping using synthetic aperture radar|
|US4630051 *||Mar 1, 1985||Dec 16, 1986||Holodyne Ltd., 1986||Imaging doppler interferometer|
|US4825213 *||Jan 12, 1987||Apr 25, 1989||Grumman Aerospace Corporation||Simultaneous triple aperture radar|
|US5579011 *||Sep 30, 1982||Nov 26, 1996||Grumman Aerospace Corporation||Simultaneous triple aperture radar|
|US6639545||May 13, 2002||Oct 28, 2003||Honeywell International Inc.||Methods and apparatus to determine a target location in body coordinates|
|US6674397||May 13, 2002||Jan 6, 2004||Honeywell International Inc.||Methods and apparatus for minimum computation phase demodulation|
|US6680691 *||May 13, 2002||Jan 20, 2004||Honeywell International Inc.||Methods and apparatus for accurate phase detection|
|US6734820||May 13, 2002||May 11, 2004||Honeywell International Inc.||Methods and apparatus for conversion of radar return data|
|US6831595 *||Mar 3, 2004||Dec 14, 2004||Fujitsu Ten Limited||Radar apparatus equipped with abnormality detection function|
|US6856279||May 13, 2002||Feb 15, 2005||Honeywell International Inc.||Methods and apparatus for determining an interferometric angle to a target in body coordinates|
|US6950056||May 13, 2002||Sep 27, 2005||Honeywell International Inc.||Methods and apparatus for determination of a filter center frequency|
|US7520464 *||Jan 4, 2006||Apr 21, 2009||Lockheed Martin Corporation||Spinning threat roll bearing estimator|
|US7952515 *||Feb 26, 2009||May 31, 2011||Mcewan Technologies, Llc||Range gated holographic radar|
|US20040174292 *||Mar 3, 2004||Sep 9, 2004||Osamu Isaji||Radar apparatus equipped with abnormality detection function|
|WO1986005279A1 *||Jan 28, 1986||Sep 12, 1986||Gene Wylie Adams||Imaging doppler interferometer|
|U.S. Classification||342/107, 342/161|
|International Classification||G01S13/00, G01S13/90|


text:
Yash and Radhika are the most loved couple in Tollywood. They met on the sets of Television show Nandagokul and became friends and soon their friendship turned into love and they came into relationship. They got into a relationship only 10 years after being friends. They dated for six years and got married in 2016. They are the most loved couple in the industry.
When they first met, they didn’t talk much and Radhika thought that Yash has an attitude. Later on, they became close friends that they shared each and everything of their life with each other. They worked together in their movie Moggina Manasu. They are the real inspiration for all the people out there for true friendship and couple goals. Radhika took six months to say Yes to Yash. They are the power couple of Kannada cinema. People love their chemistry. Their love story is one of our favorites. People love them as an on-screen couple and also as an off-screen couple too. They are madly in love with each other and sets major couple goals.
Check out some amazing pictures of Yash and Radhika and stay tuned to IWMbuzz.com

domain: entertainment


text:
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domain: design


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After releasing the turn-based, apocalyptic strategy title Mutant Year Zero: Road To Eden back in 2018, development team The Bearded Ladies has a brand-new game coming, and you won’t have to wait long to play it.
After its official announcement late last week, it turns out Corruption 2029 will officially launch for PC on February 17. In just one week.
A turn-based title like Year Zero, there seems to be a heavy focus on tactics once again, with players taking control of a squad of heavily augmented units seeking to eradicate the cause of a mysterious corruption. This tale of dystopian America is now up for pre-order on the Epic Game Store. Currently, there is no confirmed Steam release date.
If the game is like other EGS exclusives, Steam users will have to wait until 2021 to get their hands on the game.
Mutant Year Zero was previously available as a free download for a limited time on the Epic Games Store and is currently available on the EGS and Steam. It is also up for grabs on the PlayStation 4, as well as Xbox Game Pass for PC and Xbox One players.
Looking for more X-COM style turn-based strategy? Phoenix Point is also now available on Xbox Games Pass and PC and offers more alien-killing mayhem and a punishing difficulty curve.


text:
Hyderabad, Aug 25 : The Telangana government will issue notice to the industries who have not started their operations even after being allocated lands.
Minister for Information Technology and Industry K.T. Rama Rao on Tuesday asked the officials to issue the notices.
Reviewing the ongoing initiatives of the Telangana State Industrial Infrastructure Corporation Ltd (TSIIC), he directed the officials to monitor the progress of various industries that have been allotted lands in the state to ensure they start production in a time-bound manner.
He also asked the officials to prepare a detailed blue book with complete information of the industries in a sector-wise manner. This information, he said, will be useful for the government to come up with policies and programmes.
KTR also launched the e-SFC 360 view digital platform of the Telangana State Financial Corporation. He also reviewed its works and instructed the officials to expand their operations. He assured that the government will provide complete support to the corporation.
The minister also reviewed the works of Hyderabad Pharma City. Chief Secretary Somesh Kumar and heads of Departments of Finance, Industries, and Municipal Administration and Urban Development participated in the meeting.
KTR stated that the Pharma City will be pollution-free and international standards would be maintained.
The Pharma City will have zero liquid discharge units, and arrangements will be made for the centralised treatment of the waste material from it. The Hyderabad Pharma City will be set up in a live, work, and learn model where the employees can reside on the same campus.
The minister instructed the officials to start skill training centres to train the local youth who will be given top priority during the recruitment by the companies in the Pharma City.
Disclaimer: This story is auto-generated from IANS service.

domain: news


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- March 1, 2014


NFL partnered with the Soil Conservation Council of Canada to promote soil health and their campaign to raise awareness with their campaign. NFL held a contest for all NFL funded school gardens across the country. The foundation shipped over 40 pairs of underwear to over 35 NFL funded school gardens during National Soil Conservation Week (3rd week of April). The underwear needed to be buried for a maximum of 10 weeks, to gauge the school gardens soil health. The winning school garden was Lacombe Composite School, Lacombe Alberta. Congratulations!
There were a few honorable mentions, West Kent Elementary, Charlottetown PE, Churchbridge Public School, Churchbridge SK, Waterford Valley High School, St.John’s NL,Ecole Pierre Chiasson, Deblois PE. Thanks to all of the schools who participated.
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Most Cited Building and Environment Articles
Volume 43, Issue 4, April 2008, Pages 661-673
Crawley, D.B. | Hand, J.W. | Kummert, M. | Griffith, B.T.
For the past 50 years, a wide variety of building energy simulation programs have been developed, enhanced and are in use throughout the building energy community. This paper is an overview of a report, which provides up-to-date comparison of the features and capabilities of twenty major building energy simulation programs. The comparison is based on information provided by the program developers in the following categories: general modeling features; zone loads; building envelope and daylighting and solar; infiltration, ventilation and multizone airflow; renewable energy systems; electrical systems and equipment; HVAC systems; HVAC equipment; environmental emissions; economic evaluation; climate data availability, results reporting; validation; and user interface, links to other programs, and availability. © 2006 Elsevier Ltd. All rights reserved.
Volume 44, Issue 4, April 2009, Pages 848-858
This paper presented an overview of the tools used to predict ventilation performance in buildings. The tools reviewed were analytical models, empirical models, small-scale experimental models, full-scale experimental models, multizone network models, zonal models, and Computational Fluid Dynamics (CFD) models. This review found that the analytical and empirical models had made minimal contributions to the research literature in the past year. The small- and full-scale experimental models were mainly used to generate data to validate numerical models. The multizone models were improving, and they were the main tool for predicting ventilation performance in an entire building. The zonal models had limited applications and could be replaced by the coarse-grid fluid dynamics models. The CFD models were most popular and contributed to 70 percent of the literature found in this review. Considerable efforts were still made to seek more reliable and accurate models. It has been a trend to improve their performance by coupling CFD with other building simulation models. The applications of CFD models were mainly for studying indoor air quality, natural ventilation, and stratified ventilation as they were difficult to be predicted by other models. © 2008 Elsevier Ltd. All rights reserved.
Volume 43, Issue 4, April 2008, Pages 480-493
Alexandri, E. | Jones, P.
This paper discusses the thermal effect of covering the building envelope with vegetation on the microclimate in the built environment, for various climates and urban canyon geometries. A two-dimensional, prognostic, micro scale model has been used, developed for the purposes of this study. The climatic characteristics of nine cities, three urban canyon geometries, two canyon orientations and two wind directions are examined. The thermal effect of green roofs and green walls on the built environment is examined in both inside the canyon and at roof level. The effects of this temperature decrease on outdoors thermal comfort and energy savings are examined. Conclusions are drawn on whether plants on the building envelope can be used to tackle the heat island effect, depending on all these parameters taken into consideration. © 2006 Elsevier Ltd. All rights reserved.
Volume 44, Issue 9, September 2009, Pages 1899-1906
Chen, J. | Poon, C.-s.
Heterogeneous photocatalysis has been intensively studied in recent decades because it only requires photonic energy to activate the chemical conversion contrasting with conventional catalysis which needs heat for thermo-activation. Over the years, the theories for photochemical activity of photocatalyst including photo-induced redox reaction and super-hydrophilic conversion of TiO2 itself have been established. The progress in academic research significantly promotes its practical applications, including the field of photocatalytic construction and building materials. TiO2 modified building materials are most popular because TiO2 has been traditionally used as a white pigment. The major applications of TiO2 based photocatalytic building materials include environmental pollution remediation, self-cleaning and self-disinfecting. The advantage of using solar light and rainwater as driving force has opened a new domain for environmentally friendly building materials. In this paper, the basic reaction mechanisms on photocatalyst surface under the irradiation of ultraviolet and their corresponding applications in building and construction materials are reviewed. The problems faced in practical applications and the trends for future development are also discussed. © 2009 Elsevier Ltd. All rights reserved.
Life cycle assessment in buildings: State-of-the-art and simplified LCA methodology as a complement for building certification
Volume 44, Issue 12, December 2009, Pages 2510-2520
Zabalza Bribián, I. | Aranda Usón, A. | Scarpellini, S.
The paper presents the state-of-the-art regarding the application of life cycle assessment (LCA) in the building sector, providing a list of existing tools, drivers and barriers, potential users and purposes of LCA studies in this sector. It also proposes a simplified LCA methodology and applies this to a case study focused on Spain. The thermal simulation tools considered in the Spanish building energy certification standards are analysed and complemented with a simplified LCA methodology for evaluating the impact of certain improvements to the building design. The simplified approach proposed allows global comparisons between the embodied energy and emissions of the building materials and the energy consumption and associated emissions at the use stage. The results reveal that embodied energy can represent more than 30% of the primary energy requirement during the life span of a single house of 222 m2 with a garage for one car. The contribution of the building materials decreases if the house does not include a parking area, since this increases the heated surface percentage. Usually the top cause of energy consumption in residential building is heating, but the second is the building materials, which can represent more than 60% of the heating consumption. © 2009 Elsevier Ltd. All rights reserved.
Volume 44, Issue 3, March 2009, Pages 437-445
Zheng, X. | Zhong, T. | Liu, M.
Crowd evacuation of a building has been studied over the last decades. In this paper, seven methodological approaches for crowd evacuation have been identified. These approaches include cellular automata models, lattice gas models, social force models, fluid-dynamic models, agent-based models, game theoretic models, and approaches based on experiments with animals. According to available literatures, we discuss the advantages and disadvantages of these approaches, and conclude that a variety of different kinds of approaches should be combined to study crowd evacuation. Psychological and physiological elements affecting individual and collective behaviors should be also incorporated into the evacuation models. © 2008 Elsevier Ltd. All rights reserved.
Optimum insulation thicknesses for building walls with respect to cooling and heating degree-hours in the warmest zone of Turkey
Volume 43, Issue 6, June 2008, Pages 1055-1064
Thermal insulation is one of the most effective energy conservation measures for cooling and heating in buildings. Therefore, determining and selecting the optimum thickness of insulation is the main subject of many engineering investigations. In this study, the determination of optimum insulation thickness on external walls of buildings is comparatively analyzed based on annual heating and cooling loads. The transmission loads, calculated by using measured long-term meteorological data for selected cities, are fed into an economic model (P1-P2 method) in order to determine the optimum insulation thickness. The degree-hours method that is the simplest and most intuitive way of estimating the annual energy consumption of a building is used in this study. The results show that the use of insulation in building walls with respect to cooling degree-hours is more significant for energy savings compared to heating degree-hours in Turkey's warmest zone. The optimum insulation thickness varies between 3.2 and 3.8 cm; the energy savings varies between 8.47 and 12.19 $/m2; and the payback period varies between 3.39 and 3.81 years depending on the cooling degree-hours. On the other hand, for heating load, insulation thickness varies between 1.6 and 2.7 cm, energy savings varies between 2.2 and 6.6 $/m2, and payback periods vary between 4.15 and 5.47 years. © 2007 Elsevier Ltd. All rights reserved.
Application of the analytic hierarchy process (AHP) in multi-criteria analysis of the selection of intelligent building systems
Volume 43, Issue 1, January 2008, Pages 108-125
Wong, J.K.W. | Li, H.
The availability of innumerable intelligent building (IB) products, and the current dearth of inclusive building component selection methods suggest that decision makers might be confronted with the quandary of forming a particular combination of components to suit the needs of a specific IB project. Despite this problem, few empirical studies have so far been undertaken to analyse the selection of the IB systems, and to identify key selection criteria for major IB systems. This study is designed to fill these research gaps. Two surveys: a general survey and the analytic hierarchy process (AHP) survey are proposed to achieve these objectives. The first general survey aims to collect general views from IB experts and practitioners to identify the perceived critical selection criteria, while the AHP survey was conducted to prioritize and assign the important weightings for the perceived criteria in the general survey. Results generally suggest that each IB system was determined by a disparate set of selection criteria with different weightings. 'Work efficiency' is perceived to be most important core selection criterion for various IB systems, while 'user comfort', 'safety' and 'cost effectiveness' are also considered to be significant. Two sub-criteria, 'reliability' and 'operating and maintenance costs', are regarded as prime factors to be considered in selecting IB systems. The current study contributes to the industry and IB research in at least two aspects. First, it widens the understanding of the selection criteria, as well as their degree of importance, of the IB systems. It also adopts a multi-criteria AHP approach which is a new method to analyse and select the building systems in IB. Further research would investigate the inter-relationship amongst the selection criteria. © 2007 Elsevier Ltd. All rights reserved.
Volume 44, Issue 10, October 2009, Pages 2089-2096
Yao, R. | Li, B. | Liu, J.
This paper presents in detail a theoretical adaptive model of thermal comfort based on the "Black Box" theory, taking into account factors such as culture, climate, social, psychological and behavioural adaptations, which have an impact on the senses used to detect thermal comfort. The model is called the Adaptive Predicted Mean Vote (aPMV) model. The aPMV model explains, by applying the cybernetics concept, the phenomena that the Predicted Mean Vote (PMV) is greater than the Actual Mean Vote (AMV) in free-running buildings, which has been revealed by many researchers in field studies. An Adaptive coefficient (λ) representing the adaptive factors that affect the sense of thermal comfort has been proposed. The empirical coefficients in warm and cool conditions for the Chongqing area in China have been derived by applying the least square method to the monitored onsite environmental data and the thermal comfort survey results. © 2009 Elsevier Ltd. All rights reserved.
Volume 44, Issue 10, October 2009, Pages 2017-2026
Highly relevant to an individual's thermal perception, the thermal environment in outdoor public spaces impacts the use of such spaces. Thermal adaptation, which involves physiological, psychological and behavioral factors, also plays an important role in assessment of thermal environments by users. Given that these issues have rarely been addressed for outdoor environments in hot and humid regions, this study examines user thermal comfort in a public square in Taiwan. Physical measurements were taken and a questionnaire survey was used to assess the thermal comfort of subjects. The number of people visiting the square was also counted. Analytical results indicate that the thermal comfort range and neutral temperature of subjects was higher than those of people in a temperate region. Additionally, local subjects preferred a cool temperature and weak sunlight, and adapted to thermal environments by seeking shelter outdoors. Analytical results confirm the existence of thermal adaptation and illustrate the characteristics of, and variances in, thermal adaptation. During the cool season, the number of people visiting the square increased as the thermal index value increased. However, the number of people frequenting the square decreased as the thermal index increased during the hot season. These experimental results were compared with those for temperate regions, indicating that the human energy balance model cannot fully explain the influence of climate on use of public spaces; that is, psychological and behavioral factors also play important roles in outdoor thermal comfort. Study findings also elucidate design of outdoor public spaces in hot and humid regions. © 2009 Elsevier Ltd. All rights reserved.
Derivation of the adaptive equations for thermal comfort in free-running buildings in European standard EN15251
Volume 45, Issue 1, January 2010, Pages 11-17
Nicol, F. | Humphreys, M.
The equation for thermal comfort for buildings in the free-running mode (Annexe A2) in European Standard EN15251 rests on the data collected in the EU project Smart Controls and Thermal Comfort (SCATs). Many of these data were from naturally ventilated office buildings which were in free-running mode outside the heating season. Using the data from these buildings a relationship between indoor comfort and outdoor climate was developed for free-running buildings. This paper describes the data and the methods of analysis used to estimate the comfort conditions in the variable environment of free-running buildings. The paper also describes how the indoor comfort conditions were related to the running mean of the outdoor temperature, and addresses the effects of air movement and humidity. The paper considers the proportions of people likely to be comfortable if the temperature differs from the neutral temperature. The differences between the adaptive comfort charts in EN15251 and ASHRAE 55-2004 are discussed. © 2009 Elsevier Ltd. All rights reserved.
Volume 45, Issue 7, July 2010, Pages 1683-1697
Kavgic, M. | Mavrogianni, A. | Mumovic, D. | Summerfield, A. | Stevanovic, Z. | Djurovic-Petrovic, M.
Efficient and rational implementation of building stock CO2 emission reduction strategies and policies requires the application of comprehensive building stock models that have the ability to: (a) estimate the baseline energy demand of the existing building stock, (b) explore the technical and economic effects of different CO2 emission reduction strategies over time, including the impact of new technologies, and (c) to identify the effect of emission reduction strategies on indoor environmental quality. The aims of this paper are fourfold: (a) to briefly describe bottom-up and top-down methods and overview common bottom-up modelling techniques (statistical and building physics based), (b) to critically analyse the existing bottom-up building physics based residential energy models focusing on their purposes, strengths, and shortcomings, (c) to compare five building physics based bottom-up models focusing on the same building stock - UK case study, and (d) to identify the next generation of coupled energy-health bottom-up building stock models. This paper has identified three major issues which need to be addressed: a) the lack of publicly available detailed data relating to inputs and assumptions, as well as underlying algorithms, renders any attempt to reproduce their outcomes problematic, b) lack of data on the relative importance of input parameter variations on the predicted demand outputs, and c) uncertainty as to the socio-technical drivers of energy consumption - how people use energy and how they react to changes in their home as a result of energy conservation measures. © 2010 Elsevier Ltd.
Volume 44, Issue 12, December 2009, Pages 2463-2474
Hüsken, G. | Hunger, M. | Brouwers, H.J.H.
Air quality in inner-city areas is a topic which receives much attention nowadays but in the coming years, the overall interest on this topic will become even bigger. One major concern is caused by the reduction of the limiting values given by the European Council Directive 1999/30/EC [Relating to limit values for sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter and lead in ambient air. Official Journal of the European Communities 1999, L 163/41-60] and increasing traffic rates especially for diesel powered passenger cars and freight vehicles. A promising approach for solving the problem of nitrogen oxides (NOx) is the photochemical conversion of nitrogen oxides to low concentrated nitrates due to heterogeneous photocatalytic oxidation (PCO) using titanium dioxide (TiO2) as photocatalyst. A variety of products containing TiO2 are already available on the European market and their working mechanism under laboratory conditions is proven. However, there is still a lack of transforming the experimental results obtained under laboratory conditions to practical applications considering real world conditions. This paper presents the research conducted on photocatalytic concrete products with respect to the evaluation of air-purifying properties. The degradation process of nitric oxide (NO) under laboratory conditions is studied using a test setup for measuring the performance of photocatalytic active concrete products. The test setup uses the UV-A induced degradation of NO and is oriented on the ISO standard ISO 22197-1:2007. Besides the introduction of the test setup, a uniform measuring procedure is presented to the reader which allows for an evaluation and direct comparison of the performance of photocatalytic active concrete products. This kind of direct comparison was not possible so far. Furthermore, the results of a comparative study on varying photocatalytic concrete products of the European market will be discussed. © 2009 Elsevier Ltd. All rights reserved.
Experimental energy and exergy analysis of a double-flow solar air heater having different obstacles on absorber plates
Volume 43, Issue 6, June 2008, Pages 1046-1054
This paper presents an experimental energy and exergy analysis for a novel flat plate solar air heater (SAH) with several obstacles and without obstacles. For increasing the available heat-transfer area may be achieved if air is flowing simultaneously and separately over and under the different obstacle absorbing plates, instead of only flowing either over or under the different obstacle absorbing plates, leading to improved collector efficiency. The measured parameters were the inlet and outlet temperatures, the absorbing plate temperatures, the ambient temperature, and the solar radiation. Further, the measurements were performed at different values of mass flow rate of air and different levels of absorbing plates in flow channel duct. After the analysis of the results, the optimal value of efficiency is middle level of absorbing plate in flow channel duct for all operating conditions and the double-flow collector supplied with obstacles appears significantly better than that without obstacles. At the end of this study, the exergy relations are delivered for different SAHs. The results show that the largest irreversibility is occurring at the flat plate (without obstacles) collector in which collector efficiency is smallest. © 2007 Elsevier Ltd. All rights reserved.
Volume 44, Issue 2, February 2009, Pages 319-330
One of the most challenging issues presently facing policymakers and public administrators in Italy concerns what to do with waste materials from building dismantling activities and to understand whether, and to what extent, the ever-increasing quantity of demolition waste can replace virgin materials. The paper presents the results from a research programme that was focused on the life cycle assessment (LCA) of a residential building, located in Turin, which was demolished in 2004 by controlled blasting. A detailed LCA model was set-up, based on field measured data from an urban area under demolition and re-design, paying attention to the end-of-life phase and supplying actual data on demolition and rubble recycling. The results have demonstrated that, while building waste recycling is economically feasible and profitable, it is also sustainable from the energetic and environmental point of view. Compared to the environmental burdens associated with the materials embodied in the building shell, the recycling potential is 29% and 18% in terms of life cycle energy and greenhouse emissions, respectively. The recycling potential of the main building materials was made available in order to address future demolition projects and supply basic knowledge in the design for dismantling field. © 2008 Elsevier Ltd. All rights reserved.
Experimental and numerical investigation of airflow and contaminant transport in an airliner cabin mockup
Volume 44, Issue 1, January 2009, Pages 85-94
Zhang, Z. | Chen, X. | Mazumdar, S. | Zhang, T. | Chen, Q.
The study of airflow and contaminant transport in airliner cabins is very important for creating a comfortable and healthy environment. This paper shows the results of such a study by conducting experimental measurements and numerical simulations of airflow and contaminant transport in a section of half occupied, twin-aisle cabin mockup. The air velocity and air temperature were measured by ultrasonic and omni-directional anemometers. A gaseous contaminant was simulated by a tracer gas, sulfur hexafluoride or SF6, and measured by a photo-acoustic multi-gas analyzer. A particulate contaminant was simulated by 0.7 μm di-ethyl-hexyl-sebacat (DEHS) particles and measured by an optical particle sizer. The numerical simulations used the Reynolds averaged Navier-Stokes equations based on the RNG k-ε model to solve the air velocity, air temperature, and gas contaminant concentration; and employed a Lagrangian method to model the particle transport. The numerical results quantitatively agreed with the experimental data while some remarkable differences exist in airflow distributions. Both the experimental measurements and computer simulations were not free from errors. A complete and accurate validation for a complicated cabin environment is challenging and difficult. © 2008 Elsevier Ltd. All rights reserved.
Volume 45, Issue 1, January 2010, Pages 213-221
Lin, T.-P. | Matzarakis, A. | Hwang, R.-L.
Shading affects outdoor thermal environments and, therefore, influences the thermal perceptions of people in outdoor spaces. Since most field studies examining outdoor thermal comfort merely elucidated characteristics measured on a particular day, these studies may not represent annual thermal conditions accurately. Therefore, this study conducted 12 field experiments to analyze outdoor thermal conditions on a university campus in central Taiwan, and utilized RayMan model for predicting long-term thermal comfort applying meteorological data for a 10-year period. The physiologically equivalent temperature (PET) is employed as a thermal index. The thermal comfort range of Taiwanese residents obtained in a previous survey was applied as the criterion for determining whether a thermal environment is comfortable or uncomfortable. Analytical results indicate that the sky view factor (SVF), which represents the percentage of free sky at specific locations, significantly affects outdoor thermal environments. Analytical results indicate that a high SVF (barely shaded) causes discomfort in summer and a low SVF (highly shaded) causes discomfort in winter. As Taiwan has hot summers and mild winters, sufficient shading should be provided by trees and buildings to improve thermal comfort in summer. However, since the Taiwanese have poor tolerance of cold temperature, outdoor space planning should avoid creating areas with excessive shading. Therefore, the thermal requirements of residents and characteristics of the local climate and environment must be considered when creating shaded outdoor areas. © 2009 Elsevier Ltd. All rights reserved.
Volume 43, Issue 12, December 2008, Pages 2163-2177
Haldi, F. | Robinson, D.
During the warm summer of 2006 a comprehensive longitudinal field survey of the adaptive actions of occupants, their thermal satisfaction and the coincident environmental conditions was conducted in eight Swiss office buildings. We have applied logistic regression techniques to these results to predict the probability of occupants' actions to adapt both personal (clothing, activity and drinking) and environmental (windows, doors, fans and blinds) characteristics. We have also identified, for each type of control action exercised, the increases in temperature at which thermal sensation votes are reported. These "empirical adaptive increments" have also been defined for combinations of control action. In this paper we present the field survey methodology as well as the results relating to the above, which we discuss along with scope for further related work. © 2008 Elsevier Ltd. All rights reserved.
Volume 44, Issue 12, December 2009, Pages 2378-2395
Haldi, F. | Robinson, D.
Based on almost seven years of continuous measurements, we have analysed in detail the influence of occupancy patterns, indoor temperature and outdoor climate parameters (temperature, wind speed and direction, relative humidity and rainfall) on window opening and closing behaviour. In this we have also considered the variability of behaviours between individuals. This paper begins by presenting some of the key findings from these analyses. We go on to develop and test several modelling approaches, including logistic probability distributions, Markov chains and continuous-time random processes. Based on detailed statistical analysis and cross-validation of each variant, we propose a hybrid of these techniques which models stochastic usage behaviour in a comprehensive and efficient way. We conclude by describing an algorithm for implementing this model in dynamic building simulation tools. © 2009 Elsevier Ltd. All rights reserved.
Volume 43, Issue 4, April 2008, Pages 406-414
Demeestere, K. | Dewulf, J. | De Witte, B. | Beeldens, A. | Van Langenhove, H.
This paper reports the potential of heterogeneous photocatalysis as an advanced oxidation technology for removal of toluene from air using TiO2 as a photocatalyst in building materials. First, the photocatalytic activity of two types of TiO2 containing building materials, i.e. roofing tiles and corrugated sheets, has been investigated at ambient conditions (T=25.0 °C; relative humidity RH=47%; toluene inlet concentration [TOL]in=17-35 ppbv). Toluene removal efficiencies up to 63% were observed at a gas residence time (τ) of 17 s. Second, the effect of RH (1-77%), [TOL]in (23-465 ppmv) and τ (17-115 s) on toluene removal has been systematically investigated using TiO2 containing roofing tiles as photocatalytic building materials. Results revealed lower toluene removal efficiencies at higher RH and [TOL]in, whereas a positive effect was observed with increased τ. Under optimal conditions, toluene removal efficiencies up to 78±2% and elimination rates higher than 100 mg h-1 m-2 roofing tile were obtained. A decline in photocatalytic activity by a factor of 2 was observed after operation at gas residence times shorter than 69 s and [TOL]in higher than 76 ppmv. Washing the building materials with deionized water, simulating rainfall, could partially (i.e. by a factor 1.3) regenerate the catalyst activity. © 2007 Elsevier Ltd. All rights reserved.
Policies and technical guidelines for urban planning of high-density cities - air ventilation assessment (AVA) of Hong Kong
Volume 44, Issue 7, July 2009, Pages 1478-1488
In 2003, Hong Kong was hit by severe acute respiratory syndrome (SARS) from which many people died. The Hong Kong Government subsequently set up a Governmental Team Clean Committee to investigate possible urban design policies. Team Clean charged the task to the Planning Department, HKSAR. In 2003, it initiated a study titled: "Feasibility Study for Establishment of Air Ventilation Assessment (AVA) System." A number of focused studies were conducted. It eventually led to the technical methodology and guidelines of the air ventilation assessment (AVA) system. Unlike many countries with guidelines for dealing with gust wind problems, AVA is a guideline for weak wind conditions specifically designed to deal with congested urban conditions. The AVA system basically establishes a method for project developers to objectively assess their designs. In 2006, the government of Hong Kong officially adopted the system and required all major publicly funded development projects to undertake the assessment. The scientific and implementation processes leading to the AVA system are reported in this paper. © 2008 Elsevier Ltd. All rights reserved.
Assessment of climate change impact on residential building heating and cooling energy requirement in Australia
Volume 45, Issue 7, July 2010, Pages 1663-1682
Wang, X. | Chen, D. | Ren, Z.
This study investigated the potential impact of climate change on the heating and cooling (H/C) energy requirements of residential houses in five regional climates varying from cold to hot humid in Australia. Nine General Circulation Models (GCMs) under three carbon emission scenarios were applied to project the local climate. It was found that significant climate change impact on H/C energy requirements may occur within the lifespan of existing housing stock. The total H/C energy requirement of newly constructed 5 star houses is projected to vary significantly in the range of -26% to 101% by 2050 and -48% to 350% by 2100 given the A1B, A1FI and 550 ppm stabilisation emission scenarios, dependent on the existing regional climate. In terms of percentage change, houses in an H/C balanced temperate climate such as Sydney is found to be the most sensitive to climate change, potentially posing more pressures on the capacity of local energy supply. It was also found that energy efficient or high star rating houses may experience less absolute changes in energy requirement. However, they appear to experience higher percentage changes in the total H/C energy requirement. Especially in the regions with an H/C balanced temperate climate such as Sydney, the increase in the total H/C energy requirement is projected up to 120% and 530% for a 7 star house when the global temperature increases 2 °C and 5 °C respectively. The high sensitivity to global warming may need to be considered in the planning of future energy requirement for energy efficient buildings. © 2010 Elsevier Ltd. All rights reserved.
Volume 45, Issue 1, January 2010, Pages 150-157
Kang, J. | Zhang, M.
The main objective of this research was to identify factors that characterise the soundscape in urban open public spaces. The research was carried out through a series of field surveys. Stage one, as a pilot study, was a soundscape walk with 48 students in four typical urban open public spaces in Sheffield. Stage two was a detailed soundscape evaluation in two of the sites, with a total sample size of 491 from the general public. Stage three examined the soundscape evaluation by designers, with 223 architectural students. Semantic differential analysis of the results shows that although the description and evaluation of the soundscape in urban open public spaces is rather complicated, it is still possible to identify major factors which include relaxation, communication, spatiality and dynamics. In terms of the general soundscape evaluation, differences between sound level and acoustic comfort evaluation, sound preferences, and effects of demographic factors are briefly discussed. Compared to the general public, designers have stronger preferences to natural sounds and green spaces, and there is also more diversity in their evaluation. © 2009 Elsevier Ltd. All rights reserved.
Life cycle assessment of building materials: Comparative analysis of energy and environmental impacts and evaluation of the eco-efficiency improvement potential
Volume 46, Issue 5, May 2011, Pages 1133-1140
Zabalza Bribián, I. | Valero Capilla, A. | Aranda Usón, A.
The building industry uses great quantities of raw materials that also involve high energy consumption. Choosing materials with high content in embodied energy entails an initial high level of energy consumption in the building production stage but also determines future energy consumption in order to fulfil heating, ventilation and air conditioning demands.This paper presents the results of an LCA study comparing the most commonly used building materials with some eco-materials using three different impact categories. The aim is to deepen the knowledge of energy and environmental specifications of building materials, analysing their possibilities for improvement and providing guidelines for materials selection in the eco-design of new buildings and rehabilitation of existing buildings.The study proves that the impact of construction products can be significantly reduced by promoting the use of the best techniques available and eco-innovation in production plants, substituting the use of finite natural resources for waste generated in other production processes, preferably available locally. This would stimulate competition between manufacturers to launch more eco-efficient products and encourage the use of the Environmental Product Declarations.This paper has been developed within the framework of the " LoRe-LCA Project" co-financed by the European Commission's Intelligent Energy for Europe Program and the " PSE CICLOPE Project" co-financed by the Spanish Ministry of Science and Technology and the European Regional Development Fund. © 2010 Elsevier Ltd.
Volume 45, Issue 8, August 2010, Pages 1890-1904
Fioretti, R. | Palla, A. | Lanza, L.G. | Principi, P.
Performance of vegetated roofs are investigated in terms of their expected benefits for the building and the urban environment, due to their recognised energy and water management potential scores. A review of related worldwide experiences is reported for comparison purposes. The investigation is here performed within the specific climatic context of the Mediterranean region. Full-scale experimental results are provided from two case studies, located in north-west and central Italy, consisting in two fully monitored green roofs on top of public buildings. The attenuation of solar radiation through the vegetation layer is evaluated as well as the thermal insulation performance of the green roof structure. The daily heat flow through the roof surface is quantified showing that the green roof outperforms the reference roof, therefore reducing the daily energy demand. As for water management, it is confirmed that green roofs significantly mitigate storm water runoff generation - even in a Mediterranean climate - in terms of runoff volume reduction, peak attenuation and increase of concentration time, although reduced performance could be observed during high precipitation periods. © 2010 Elsevier Ltd.

domain: literature


Nowadays, the number of mobile users is rapidly growing. The significant traffic is driven by internet penetration and partial displacement of televisions and computers with telephones that provide convenient and constant access to information.
According to Statista, the number of smartphone users worldwide today is six billion and is predicted to grow by several hundred million in the next few years. That's why there is a need to use new technologies for mobile application development. This article observes the best tech stack for mobile app development in 2024 that you can consider for building your app.
What is the technology stack for mobile app development?
The mobile app development tech stack is a set of technologies that are used to build and run a mobile application. This concept includes frameworks, programming languages, UX/UI design tools, and other instruments that are required for mobile app development. This technology stack for mobile must meet the requirements of building an app and the type of future product.
Sometimes companies need help creating a mobile app, such as a lack of resources and platforms, wrong estimation and development directions, and poor user experience.
Choosing the best tech stack guarantees the scale, security, and efficiency of application development. Also, app technology affects the speed of entering the general market and the development cost. To develop a reliable mobile application for your business, you need to consult with professionals.
Conforming to Zippia research, 38% of users will stop interacting with a poorly and inconveniently designed mobile app. Therefore, we highlight the best tech stack for mobile app development in 2024. Let's find out the difference between each component of it.
4 Elements of tech stack for mobile applications
We can divide tech stack for mobile app development into four categories:
Back-end. Software development stores and organizes data and ensures everything on the client side actually works. For example, customers log into an account or shop online. In fact, the back-end responds to user requests, accesses the database and executes the create/read/update/delete operations.
Front-end. Development technologies that can help you with building the interface for interaction with your users. The mobile app's layout includes the interface developers' products, such as buttons, animations, hush function, business logic, and links. Thus, a mobile app's back-end handles the server-side code and the database.
Platform. A mobile platform such as iOS or Android provides the operating system and development tools to build and run the app. This might include technologies like iOS SDK or Android SDK and programming languages such as Objective-C, Swift, Java, or Kotlin.
Hosting. Hosting ensures that server-side code runs and provides the application to users. This hosting environment includes Linux, Apache, and Amazon Web Services (AWS).
These critical steps determine the application's features, programming languages, tools, and the team you work with.
Is there a big difference between the tech stack for iOS and Android apps?
Android and iOS are the most popular mobile operating systems worldwide. Also, Windows, Tizen, and BlackBerry OS are considered standard.
Based on Statista’s data, Android is the leading mobile operating system worldwide in November 2022, which controls the mobile OS market with a 71% share, while iOS accounts for about 28% of the mobile operating system market.
It is essential to highlight that there are different mobile applications, such as native and hybrid (or cross-platform) mobile apps. A native app is a software program that is used on a particular platform or device.
It has excellent functionality and high user experience, but the development of native apps takes a long time and has a higher price compared with hybrid apps. That is why native mobile app development requires specific technology stacks and specialists for the development process.
Hybrid apps, at the same time, combine elements of both native apps and web apps. Simply put, it is developed with technologies that give apps cross-platform functionality.
The most famous examples of native apps are Uber, Instagram, Twitter, and Gmail. It is cost-effective, faster, and easier to build hybrid apps. However, they have such drawbacks as test complexity and lower performance.
Consequently, each type of mobile app requires unique programming languages, tools, and technologies for mobile development and maintenance processes. Let's explore them in more detail below.
Technology stack for Android apps
As already mentioned Android mobile applications have a larger share than iOS, so let’s first consider the tech stack for the Android apps.
Programming languages for Android apps
There are many different languages for different types of mobile application development. The choice of one or another language depends on the particular kind of app you want to develop. The most popular Android programming languages are Java and Kotlin.
Java is the most popular for Android app development because it’s an object-oriented programming language that allows more straightforward problem-solving using a modular structure. The most valuable benefits of using Java for mobile app development are widespread popularity, security, robustness, numerous features that affect app performance, such as Just-In-Time compilation, and community support.
Kotlin is a statically typed programming language that enables developers to compile code to Java. It is fully compatible with Java virtual machine (JVM), so you can use Java frameworks for developing the app. One of the main benefits of using this programming language is faster compilation time. However, Kotlin is still an evolving language. Therefore, there are still configuration issues and limitations to supporting new Android app development devices.
|Null pointer exception
|Support for complex architecture
|Uber, Airbnb, Amazon
|Udemy, Trivago, Plaid
Development tools for Android mobile apps
A development tool is a program used by software developers to build, test, maintain or support other programs and apps. Before choosing a mobile app technology, you have to analyze the features and requirements of the future mobile application and choose the best technology stack that meets your business's functional requirements.
These tools are also divided into two groups: for Android and iOS mobile app development.
Development tools for Android mobile apps:
Android Studio provides app builders with an integrated development environment optimized for Android apps. This Android tech stack is an open source for mobile app development that offers such features as visual layout editor, fast emulator, smart code editor and templates. Android Studio is a platform that helps with building an Android app with the latest features.
Android Software Development Kit (Android SDK) includes various components that can be downloaded separately. For example, the Android SDK uses code samples, libraries, multiple types of documentation, and guides to create Android applications. Moreover, the Android SDK allows you to add a 2GIS map to your Android app. Therefore, you can use it to add unique markers, estimate routes, and get information about map objects.
By the way, these tools are actively used by large companies. Do you want to know which companies? Here are some examples.
UI frameworks for Android mobile apps
What do we know about the UI framework (or user interface framework)? It is the software that defines a structure for user interfaces. It is a system that allows building and modifying UI components. Developers can use UI frameworks to create user interfaces for mobile applications on Android or iOS devices.
UI frameworks for Android mobile apps:
Android UI has templates for faster building user interfaces. This Android tech stack provides action bars and content areas: view control, content area, main action bar, and split action bar.
Jetpack Compose is a framework that helps to create the UI. The main benefits of using this tech stack are simpler code, powerful tools, and intuitive Kotlin APIs. This modern toolkit for building native apps has a simple UI for Android development. Jetpack Compose can quickly bring your app to life without extended code, using appropriate tools and intuitive Kotlin APIs.
Jetpack Compose UI app development toolkit is an intuitive and powerful UI framework. To make sure of this, let's watch the following video.
Technology stack for iOS apps
Mobile tech stacks are like the backbone of the app that makes the platform user-friendly that helps in making the product popular among the users. Now, let’s discuss in a detailed manner the technology stacks to be used in iOS mobile app development.
Programming languages for iOS apps
Objective-C and Swift are the most common programming languages that are used for iOS app development. Each has features and can provide mobile app development according to your business needs.
Objective-С was once the primary programming language for building iOS apps. It is strict, complex, and has good data protection features. It is also compatible with various Apple platforms like iPhone, Mac computers, Apple TVs, and iPads.
However, Objective-C is considered relatively outdated as it was last updated in 2016. Developers may still use it for specific components that have not been ported to Swift.
Swift is a modern programming language with an expressive syntax, so mobile app development takes fewer resources. It also has an automatic memory management system and a concise code that allows developers to save time writing mobile apps. Swift structures various data, flow controls and protocols. Also, Swift is a cross-platform language, particularly used for Windows and Linux.
|Requires a lot of steps
|Requires less code lines
|Difficult to maintain
|Easy to maintain
|Slow bug fixing
|Fast bug fixing
|Supports only Cocoa API
|Supports all APIs
Swift and Objective-С are both used for iOS app development. PYPL index survey shows that 2.23% of respondents share Swift, whereas 2.22% share Objective-C, making it an approximate 1:1.
Development tools for iOS apps
There are many iOS development tools available today, but we highlighted the solutions that improve the quality of apps and streamline your development process. Whether you're a beginner or an expert, you'll be able to find what you're looking for in this list.
But before that, we need to understand two additional things. IDE (integrated development environment) is a comprehensive environment for writing, testing, and debugging code. An SDK (software development kit) is a set of tools, libraries, and documentation specific to a platform or technology. An SDK can be used within an IDE to develop applications for a particular platform.
Now, let’s check development tools list for iOS mobile apps:
Apple Xcode and AppCode are both IDEs used for iOS app development, with Xcode being Apple's official and most widely used IDE.
The iOS Software Development Kit (iOS SDK) is a set of tools and frameworks necessary for building iOS apps and is integrated into both Xcode and AppCode. Choosing between AppCode and Xcode often depends on personal preference and specific development requirements.
UI frameworks for iOS mobile apps
The SwiftUI, UIKit and others frameworks allow you to manipulate the iPhone or iPad camera, add voice interaction using SiriKit, explore music with MusicKit. Also, you can expand viewing and listening via AirPlay 2, and even add iMessage Business Chat to your application
UI frameworks list for iOS mobile apps:
SwiftUI is a modern framework created by Apple to build user interfaces for the iOS operating system. This framework allows using lists, stacks, buttons, selectors, and other components. It also provides the tools you need to create custom views, add animations, and integrate gestures. The main benefits of using SwiftUI are theme management and straightforward code creation.
UIKit is a framework that delivers many exciting features for developing apps with components for constructing the core infrastructure of your iOS, iPadOS, or tvOS apps. Moreover, UIKit operates seamlessly with the SwiftUI framework, so you can implement parts of your UIKit app in SwiftUI or combine interface elements between the two frameworks. Also, UIKit has support for animations, documents, drawing and printing, text management and display, search, app extensions, resource management, and getting information about the current device.
In the video below, you can see the detailed comparison of SwiftUI and UIKit by building a complete project.
It is important to choose the proper UI framework for your mobile app development. Each has its benefits and drawbacks, so you have to choose the tech stack according to your mobile app features and business needs.
The user interface is one of the most important things to pay attention to during mobile app creation because your customer interacts with it every day. That's why it is essential to improve the user experience as much as possible to boost customer satisfaction.
Overall, we highlight the best UI frameworks for developing an app for iOS or Android operating systems.
Cross-platform apps technology stack
First, it is essential to observe what is a cross-platform mobile application. A cross-platform app (or hybrid app) is an application with different operating systems and platforms, such as Android, iOS, or Windows. If you are looking for a mobile app technology whose target audience uses both iOS and Android, cross-platform app development can save you time and resources due to using the same codebase for different platforms.
Cross-platform apps can have native-like interfaces, but the degree of "nativeness" depends on the framework used and the implementation. These apps generally strive to offer a user experience similar to native apps while reducing development time and effort.
Next, developers utilize non-native programming languages and frameworks to create cross-platform apps for various devices and operating systems. Examples of such frameworks include React Native, Flutter, and Xamarin. This lets you quickly transfer apps to their containers and integrate the finished products into platforms. There is no reason to worry if they will work the same on different platforms. The answer is yes.
The popularity of using cross-platform tech stacks for mobile is growing nowadays. Based on Developer Survey, the most popular multi-platform mobile framework is Flutter, which is used by more than 12.64% of software professional developers. The next most used are React Native (12.57%), Ionic (5.27%), Xamarin (5.21%), and Cordova (4.15%).
Programming tools for cross-platform mobile apps
There are so many different options to choose for cross platform mobile app development. It can be difficult to narrow down which ones are the best for cross platform apps. However, let's take a closer look at the following cross-platform development tools.
The main benefit of using this tech stack is the ability to create one code without separating it for different operating systems. This reduces time and increases the productivity of mobile app development.
The second most popular mobile stack for cross-platform app development. The main feature is hot reloading which reduces code development time. It is helpful for fast application development on any platform, which reduces code development time.
Also, Flutter has a wide variety of ready-made widgets, so you can use and customize them according to your mobile app tech stack needs. Besides, flutter apps are created directly into the machine code, which minimizes performance bugs.
The Flutter architectural overview is divided into several sections. For example, the layer model is about the pieces from which Flutter is constructed. Also, widgets are the fundamental building blocks of Flutter user interfaces. The rendering process shows how Flutter turns UI code into pixels. Integrating Flutter with other code provides information about different techniques available to Flutter apps. Below are the main parts and layers of the Flutter framework’s architecture in more detail.
An open-source framework for developing modern and performant iOS and Android operating systems applications. This tech stack for the mobile app is used to create cross-platform apps in C#. Also, it is possible to share and test code, improving the business logic across platforms.
The main features of using Xamarin are modern language constructs, a robust base class library, and an integrated development environment with Visual Studio. All these benefits allow developers to build mobile apps more easily.
Xamarin apps run within the Mono execution environment and use AOT (full Ahead of Time) compilation to compile C# code to native. The Mono runtime is written in the C language and runs side-by-side with the Objective-C Runtime. Both runtime environments run on top of the UNIX-like kernel, specifically XNU, and expose various APIs to access the underlying ios system. Below is a visual answer to the question, "What’s the architecture of Xamarin?"
Simply put, cross-platform applications are technology stacks used to develop applications for various operating systems and devices. These frameworks allow you to maximize the mobile application's target audience and distribute your app worldwide. The main features of cross-platform mobile tech stack are their portability, cost-efficiency, and broader market reach.
|Moderate to near-native
|Up to 90%
|Up to 90%
|Up to 96%
|Uses native UI controllers
|Uses customer widgets
|Uses native UI controllers
|Google Ads, Alibaba
|OLO, MRW, Storyo
Benefits and challenges of cross-platform app development
New technologies constantly contribute to the development of cross-platform mobile applications. Therefore, developers are increasingly interested in dynamic work with these applications.
The development of cross-platform applications provides the following benefits:
- Use of a single standard code that helps save the overall budget;
- Development and support of the program by only one team of programmers with basic knowledge of standard languages;
- Optimization of the native interface for easy interaction with the user;
- Engaging users with various mobile devices and a faster way to market at a lower cost.
On the other hand, you can explore specific challenges in developing cross-platform applications:
- Deterioration of application performance due to complex code of cross-platform solutions (combination of native and non-native components).
- Not capable of supporting all mobile functions (animation or 3D effects). Therefore, applications have limited functionality and a poor look and feel of the program.
- Constant delay of updates. When a new feature is added for a particular OS, cross-platform apps could take some time to reflect the same. Because the framework you use may or may not be packed with all the latest features of the latest version of releases, which leads you to lazy new updates.
As a result, cross-platform app development is best suited for your solutions if your apps do not require a complex interface or online input processing. Also, it’s a great idea to choose cross-platform app development when your apps do not need access to all device functions.
Regarding the benefits and challenges during app development at Codica, it is worth mentioning our recent project - Impact Personal Training. Our team developed such an progressive web application for fitness connecting personal fitness trainers and their clients with a mobile- and user-friendly solution.
The client wanted us to create a fitness app enabling clients to follow individual fitness programs that trainers would define for them. Such programs should include exercises, nutrition, and daily routines for clients, so users see their sports results.
The video below shows how our customer, Richard Gunter, is happy with the app’s functionality our specialists developed.
Value delivered by our development company:
- Created a fitness progressive web application from scratch based on the customer’s idea and requirements.
- Prepared desktop and mobile versions (iOS and Android apps) of the app to meet the needs of trainers and their clients. Both versions have appealing designs and intuitive functionality.
- Optimized the set of features to make the PWA lightweight and fast-loading.
- Developed a stable app handling large volumes of data.
- Improved the solution based on early feedback from users.
In general, this app lets clients get the recommended exercise set from personal trainers. The clients manage their programs with a convenient dashboard showing the training scale, today’s workout, and progress. Also, the clients can track their achievements in the fitness app by marking the exercises they completed.
10 tips to choose the best technology stack for mobile apps
It is essential to highlight that each mobile application is unique and requires a particular approach to its design and development. You should consider the functional features and the audience that will use the application. Therefore, the creation and implementation of this app require communication between business owners and the technical team.
We have highlighted the top 10 tips for creating a mobile application to facilitate working with the requirements. They will help you focus on the main aspects of developing and maintaining a mobile application.
1. The aim of the mobile app
First of all, you need to understand the purpose and tasks of the mobile application. It is essential to determine what you want to achieve in developing this mobile app, what people's needs it meets, and the values it brings. It is also worth conducting market research and analyzing the competitors to clarify what value your mobile app can bring.
Try to answer the following questions:
- What is the “problem” the product is going to solve? Isn't there an existing product that already solves this problem? Can we create a perfect version of it and get users' attention?
- What is your target audience? What do they think about this problem?
- How do your competitors solve this problem? What do they do well or not okay?
- How can your mobile application improve the customer's life?
- How can your target audience use this application? What devices do they usually use?
After receiving answers to these questions, it will be easier for you to move on and define the tech stack for mobile application development.
When your company is developing mobile apps that store personal data, it is crucial to provide security protection. A robust safety solution and data privacy play a significant role while building apps. An app should be securely protected from hackers who can:
- Get access to data stored in your mobile app or steal the user's passwords;
- Gain sensitive information about your customers;
- Steal intellectual property and private business information;
- Steal customer identifiers for fraud purposes.
That's why it is worth paying enough attention to creating a reliable application to avoid possible problems with information theft. This is crucial for the reputation of your business.
At Codica, we follow industry-standard mobile app security best practices along with a stringent security testing strategy. We firmly believe that mobile app development is about innovation and creativity with safe user experience.
Many mobile app development products require complex integration with back-end systems, adherence to regulatory requirements, and compelling user interface design that can drive the development cost. It is important to understand the complexity of the application's interactions with the underlying mobile features and communication with the back-end.
If you’re building an app that requires caching a huge amount of data, you’ll need to opt for native mobile stacks. Native app technology allows you to access features specific to the device, which isn’t possible if you’re building in a cross-platform environment.
4. Time to market
It is a great idea to focus on a simple, well-tested, and flexible tech stack for mobile development if you need to reach the market as soon as possible. For example, you can use the Swift programming language instead of Objective-C if it is essential to get to the market quickly.
By the way, the following indicators testify to the effectiveness of Swift. Let's pay attention to the SWIFT FIN. This is a message type (MT) that transmits financial information from one financial institution to another. In November 2022, Swift recorded an average of 44.8 million FIN messages daily. Therefore, traffic grew by +7.1% versus the same period of the previous year.
Many factors influence the price, depending on the complexity of the app development process. If your budget is limited, you should first create an MVP that will satisfy customers' needs and meet your business requirements. This is to reduce the initial costs and, at the same time, speed up the launch of the application.
Regarding the cost of a mobile app, there are some factors that you need to consider as well.
|Level of complexity
|MVP functionality; basic UI
|Medium complex app
|Sophisticated features; custom UI
|Highly complex app
|High-level advanced features; bespoke UI; two platforms
Your mobile app technology must scale vertically (adding extra hardware like computers or servers) and horizontally (adding additional resources such as CPU, memory, network bandwidth, and more) while maintaining performance. Still, particular attention should be paid to frameworks. Why? There is a tradeoff between modular-based development and the ability for those modules to be scaled or modified in the future.
Beyond scalability is the base performance of the app, dictated directly by the app's business requirements and the tech stack choices. These points influence the size of the app, how fast the system reacts, and how many requests the system can process.
With performance being the first and most crucial factor in user acceptance of a new product, this factor must be a part of every decision in the tech stack for the front and back-end. It is also important to balance time to market with performance.
An instance of a project with SaaS product development services can be the real estate portal our team developed. We created a multi-page custom SaaS platform for real estate that displayed listings from homeowners. Also, we delivered a fast-loading property search website that performs equally well on all types of devices.
Moreover, our developers introduced the JAMstack approach, including the Gatsby technology, which helped us deliver a responsive, fast-loading, and intuitive SaaS for real estate. These technologies were especially valuable as the platform needed to handle much data. How does it work? We suggest you watch a short video about the functionality of this real estate SaaS platform.


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Blind Watchers of the Sky, The People and Ideas that
Shaped Our View of the Universe, Rocky Kolb, Addison Wesley 1996
A rather light weight treatment of the history of astronomy and our understanding of the universe. Sort of a tour of astronomy from Tycho to the big bang.
Skywatchers, Shamans and Kings, E. C. Krupp,
The influence of astronomy on archaeology, or perhaps vice versa. Interesting light reading.
In Search of Planet Vulcan - The Ghost in Newton's
Clockwork Universe, Baum and Sheean, Plenum Trade 1997
This is a nice little book and an easy read about the search for a planet supposedly causing perturbations of Mercury's orbit. Even though we know the result, it is a nicely detailed account of the predictions of Le Verrier and the attempt by his followers to find this elusive planet. The hundred year search is a study in personalities, factions, fabrication and stubborn refusal to give up the futile search. There is a large section on W. Watson an astronomer with connections to the Universities of Michigan and Wisconsin who was a diligent searcher for Vulcan..
Pluto and Charon, Alan Stern and Jacqueline
Mitton, Wiley Interscience 1998
This is a delightful book. It gives a history of the discovery of both Pluto and Charon, a very detailed and scientific discussion of analyzing the size and atmosphere of these objects and a nice discussion of the formation of the planets and our solar system. This is a readable book but has solid science underlying it.
Starseekers, Colin Wilson, Doubleday and Company 1980. This is a history of mankind and his looking to the stars. Starts with Stonehenge and ends with a whimper sometime in this century. A so so book that adds very little to our understanding of the history of astronomical activities.
The Astronomers, Companion book to the PBS television
series. Donald Goldsmith, St. Martin's Press 1991.
This is a book that defies being categorized. It goes with the television series. That's it. It's ok if you like the series.
Greenwich Time and the Longitude, Derek Howse,
Philip Wilson Publishers 1997
This is a delightful book for anyone interested in the establishment of time over the centuries. The emphasis is on the Greenwich observatory and their roll in setting time standards over the world. The chronicle covers time measurement from the hourglass to the cesium clock. It is loaded with information about the technology of time measurements and the lives of the people who improved the measurement of time over the past several centuries. This is a very nice book.
The End of the Dinosaurs, Charles Frankel, Cambridge
University Press 1999. This in small but chock full of information book
about the latest theories of how the dinosaurs vanished. It establishes
ties between many known major impact craters on the earth's surface with major
changes in the earth's development. Major astronomical catastrophes seem
to have caused major catastrophic steps in the development of the flora and
fauna of the earth over the past 500 million years. A fascinating book,
well written, authoritative and easy to read. Highly recommended.
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Nationals | Diaz agrees to one-year deal
The Seattle Post-Intelligencer reports the Washington Nationals have agreed to terms with OF Frank Diaz on a one-year deal with undisclosed financial terms.
2007-01-16 23:06:53 | Source:
Access more Frank Diaz news and rumors by clicking here....
For additional MLB information, please view KFFL's MLB Hot off the Wire.


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Klyde Warren Park presents Food Truck Frenzy
Klyde Warren Park celebrates Spring Break as it hosts the Food Truck Frenzy, presented by Nissan. The all-day event features 25 food trucks, oversized lawn games, kids’ crafts, family-friendly activities, and culminates with a live concert by local band Party Machine.
This is the third signature event presented by Nissan since the automotive brand became the official vehicle of the park and a Premier Sponsor last June. In addition, Nissan is teaming up with Klyde Warren Park to bring you the Nissan Nightlife Concert series – a six show event that is free and open to the public. The Food Truck Frenzy event serves to kick off the first concert in the series of six, which will run Thursday evenings on March 23 and April 6, 13, 20 and 27.


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If you’re considering visiting a wellness naturopathic centre in Del Mar, CA, it’s important to know what to expect. While each naturopathic facility is unique, there are some commonalities that you can expect to find.
First and foremost, naturopathic centres focus on natural and holistic healing methods. This means that you can expect treatments like hydrotherapy and herbal medicine. You may also find other services like prolotherapy and exosome therapy.
When you visit a naturopathic centre, the first thing you’ll likely do is meet with a naturopathic doctor. This initial consultation is important in order to determine the best course of treatment for your needs. The naturopathic doctor will take your medical history and perform a physical examination. They may also order some lab tests in order to rule out any underlying health conditions.
After the initial consultation, you’ll likely be given a treatment plan. This plan will likely include lifestyle changes, as well as specific naturopathic treatments. It’s important to follow the treatment plan in order to see the best results. Your provider will work with you to monitor your progress and adjust your treatment plan as needed.
If you’re considering visiting a wellness naturopathic centre in Del Mar, CA, be sure to do your research. Make sure to find a reputable centre that offers the services you’re looking for. Once you’ve found a centre you’re comfortable with, you can begin reaping the benefits of naturopathic medicine. If you’re ready to get started, visit The Wellness Club at Tulsi today.
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