US 4883409 A
A pumping apparatus for delivering liquid at a high pressure, in particular for use in liquid chromatography, comprises two pistons (10, 20) which reciprocate in pump chambers (7,18), respectively. The output of the first pump chamber (7) is connected via a valve (13) to the input of the second pump chamber (18). The pistons are driven by linear drives (30,31), e.g., ball-screw spindles. The stroke volume displaced by the piston (10) is freely adjustable by corresponding control of the angle by which the shaft of the drive motor (36) is rotated during a stroke cycle. The control circuitry is operative to reduce the stroke volume when the flow rate which can be selected by user at the user interface (42) is reduced, thus leading to reduced pulsations in the outflow of the pumping apparatus. The pumping apparatus can also be used for generating solvent gradients when a mixing valve (2) connected to different solvent containers (A,B,C,D) is coupled to the input of the pumping apparatus (FIG. 1).
1. Pumping apparatus for delivering liquid at a high pressure, comprising:
a. a first piston (10) for reciprocation in a first pump chamber (7), the first pump chamber having an inlet port (9) and an outlet port,
b. a second piston (20) for reciprocation in a second pump chamber (18), the second pump chamber having an inlet port (9') and an outlet port,
c. a conduit connection (12,14) between the outlet port of the first pump chamber and the inlet port of the second pump chamber,
d. an inlet valve (4) connected to the inlet port of the first pump chamber for allowing flow of liquid into the first pump chamber and for inhibiting flow in the opposite direction,
e. an outlet valve (13) connected to the outlet of the first pump chamber for allowing flow of liquid into the second pump chamber and for inhibiting flow in the opposite direction,
f. drive means (30,34; 31,33; 32,36) for reciprocating the first and the second piston, comprising ball-screw spindles (30,31) coupled to each of said pistons (10,20), respectively, and said drive means for each piston further comprising:
an actuating element (37) having a recess (38) for receiving a ball (27),
a ball (27) having such a diameter that it projects above the recess (38), but can freely move inside the recess,
a piston holder (25) to which the piston (10) is mounted having a surface for contacting the ball (27),
a return spring (15) for exerting a force on the piston (10) in a direction away from the pump chamber (7), and a guiding element (39) arranged between the actuating element (37) and the pump chamber (7) for guiding the piston (10), and
g. control means (41,42,43,44,35) coupled to the drive means (30,34; 31,33; 32,36) for adjusting the stroke lengths of the pistons (10,20) between their top dead center and their bottom dead center, respectively, thereby permitting an adjustment of the amounts of liquid displaced by the first and second piston, respectively, during a pump cycle such that pulsations in the flow of the liquid delivered to the output of the pumping apparatus are reduced.
2. Pumping apparatus as in claim 1, wherein each ball-screw spindle (30,31) is coupled to a gear (34,33), with the gears of the spindles being coupled to each other and to a gear (32) coupled to the axis of a common drive motor (36) such that a rotary motion of the common drive motor causes a reciprocating movement of the two pistons (10,20) with a fixed phase relationship to each other.
3. Pumping apparatus as in claim 1 wherein each ball-screw spindle (30,31) is coupled to a separate drive motor allowing an adjustment of the relative phase of the reciprocating motions of the first piston (10) and of the second piston (20).
4. Pumping apparatus as in claim 1, wherein the two pistons (10,20) are reciprocating with a phase difference of 180 degrees and that the amount of liquid delivered by the first piston (10) during a pump cycle is two times as large as the amount of liquid delivered by the second piston (20) during that pump cycle.
5. Pumping apparatus as in claim 1, further comprising a damping element (23) connected either to the outlet of the first pump chamber (7) or to the outlet of the second pump chamber (18) for damping pulsations of the flow of the delivered liquid caused by the compressibility of the liquid said damping element comprising two chambers separated by an elastic partition, one chamber receiving the liquid to be damped, the other chamber holding a damping liquid, with an insert having a selected volume and temperature expansion coefficient being provided in the chamber holding the damping liquid.
6. Pumping apparatus as in claim 1, wherein, the inlet port (9) of the first and the inlet port (9') of the second pump chamber are located at that end of the chamber, respectively, from which the piston enters the chamber during its reciprocating motion, and the outlet port of the first and the outlet port of the second chamber are located at the opposite ends of the chambers, respectively.
7. Pumping apparatus as in claim 1, wherein said pump chambers have bores (8,19) whose inner diameters are larger than the diameters of the pistons (10,20), respectively, such that liquid can flow between the pistons and the inner walls of the bores of the pump chambers into the space above the pistons, respectively, so that liquid is drawn in when the pistons move in a direction out of the pump chambers, respectively.
8. Pumping apparatus as in claim 1, wherein said control means (41,43,44,35) controls the drive means in such a way that during the reciprocating movement of the pistons, the distances which the pistons travel from their top dead center to their bottom dead center and from their bottom dead center back to their top dead center, respectively, increase linearly with time.
9. Pumping apparatus as in claim 1, wherein said control means (41,43,44,35) controls the drive means such that the stroke lengths of the pistons (10,20) is decreased when the flow rate of the delivered liquid is decreased.
10. Pumping apparatus as in claim 1, wherein adjusting the stroke length of the first piston (10) is performed by either fixing the motion of the top dead center of the piston and the varying bottom dead center or the bottom dead center is kept fixed and the top dead center is varied.
11. Pumping apparatus as in claim 1, wherein a mixing valve (2) coupled with its output to the inlet valve (4) of the first pump chamber (7), the mixing valve having a plurality of inputs (1a,1b,1c,1d), each coupled to different containers (A,B,C,D) containing different solvents, the mixing valve being responsive to control signals from a gradient controller (45) connected to the control means for establishing connections to a selected solvent container during adjustable portions of the inlet stroke of the first piston (10), so that a desired mixture of solvents can be generated.
12. Pumping apparatus as in claim 11, wherein said apparatus is used for generating solvent gradients.
The invention relates to a pumping apparatus for delivering liquid at a high pressure, in particular a pumping apparatus for solvent delivery in liquid chromatography. Such a pumping apparatus is used, e.g., in liquid chromatography to pump the mobile phase (solvents or mixtures of solvents) through the chromatographic system including the separation column. The pumping apparatus forms a part of the solvent delivery system which may comprise additional units for drawing in and for mixing solvents.
In the chromatographic analysis, it is desirable that the flow rate of the liquid delivered to the column is adjustable over a wide range of flow rates. It is furthermore desirable that the solvent delivery system permits the generation of mixtures of solvents and to change the mixing ratio of the various solvents of the mixture in the course of time (gradient operation). Such versatility of the solvent delivery system permits to optimize the analysis conditions for the specific sample to be chromatographically separated.
Although the flow rate should be adjustable, it is very important that a once adjusted flow rate is kept as constant as possible. If the flow rate through the separation column would fluctuate, variations in the retention time of the examined sample would occur so that the areas of the chromatographic peaks produced by a detector connected to the outlet of the column, e.g., an absorption detector, a fluorescence detector, or a refractive index detector, would vary. Since the peak areas are representative for the concentration of the chromatographically separated sample substances, fluctuations in the flow rate would impair the accuracy and the reproducibility of quantitative measurements.
Some pumping systems like reciprocating pumps with a single piston have inherent flow variations because the piston delivers only during a portion of a pump cycle. To reduce such pump pulsations, it is known to use a dual piston pump having two interconnected pump heads each with a reciprocating piston. The pistons are driven via cams and a cam-shaft with a predetermined phase difference so that the resulting outflow is comparatively smooth. Such a dual piston pump driven via cams and a common cam shaft is known from U.S. Pat. No. 4,352,636.
At the high pressure encountered in high performance liquid chromatography, compressiblility of the solvents becomes noticable resulting in an additional source for flow pulsations. The reason is that during each compression cycle of the pump, the first piston has to move a certain path to compress the liquid to its final delivery pressure before actual delivery of liquid starts. As a consequence thereof, pulsations in the outflow occur at the pump frequency. These flow pulsations are particularly disturbing at low flow rates. The reason is that the percent magnitude of pulsations remains substantially constant over a wide range of flow rates but that the amplitudes of the peaks in the chromatogram become smaller when the flow rate is reduced, in particular when smaller separation columns are used, so that the influence of the flow pulsations on the chromatographic results is more pronounced at lower flow rates.
From the above-mentioned patent U.S. Pat. No. 4,352,636, it is known to reduce the pulsations caused by the compressibility of the liquids by using specially designed cams which are contoured such as to produce the same amount of outflow of pressurized liquid at all points in the cycle of rotation of the cam shaft except for a short interval at the beginning of the expulsion stroke of the first piston. The thus produced precompression phase and the resulting positive outflow pulse is to compensate for compressibility of the liquid. The precompression phase is dependent on a variety of parameters like volume at the top dead centre of the first piston, stroke volume, pressure in the pump, compressibility of the liquid, stiffness of the pumping system, closing performance of the valves. Since not all of these parameters can be precisely determined, a remaining pulsation in the outflow of the pump is to be expected. Furthermore, the known pumping apparatus has a comparatively complex mechanical design requiring precisely machined cams.
Relative to this prior art, it is an object of the invention to provide a pumping apparatus for delivering liquid at high pressure according to the preamble of claim 1 which has a simpler mechanical design and which substantially avoids over a wide range of flow rates the problems caused by interferences of pulsations of the flow of the delivered liquid with the chromatographic measuring results.
According to claim 1, this object is solved for an apparatus as in the preamble in that control means are provided which are coupled to the drive means reciprocating the pistons, the control means being operative to adjust the stroke lengths of the pistons between their top dead centre and their bottom dead centre, respectively, permitting an adjustment of the amounts of liquid displaced by the first and second piston, respectively, during a pump cycle such that pulsations in the flow of the liquid delivered to the output of the pumping apparatus are reduced.
In order to see how the provision of an adjustable stroke volume leads to a reduction in the flow pulsations, the following is to be considered:
In known solvent delivery systems, the flow rate is changed by changing the frequency of reciprocation of the pistons so that the pistons move at a higher frequency when a higher flow rate is selected, whereas the stroke volume remains the same when the flow rate is altered. According to the present invention, however, the flow rate is changed by changing both the frequency of reciprocation of the pistons and the stroke volume. In a preferred embodiment of the invention, the stroke volume is decreased with the flow rate. Thus, when the stroke volume becomes smaller, the volume which has to be compressed to the final pressure before delivery starts also becomes smaller. Since the volume to be compressed is smaller, the compression phase becomes shorter resulting in smaller pulsations of the outflow of the pump.
It is a further consequence of the variation of the stroke volume as a function of the flow rate that, particularly at low flow rates, the frequency of reciprocation of the pistons is higher than in a prior art pump having a fixed stroke for all flow rates. This increase in the frequency of reciprocation leads to a corresponding increase in the frequency of any remaining pulsations of the pump output which has advantageous effects on the reproducibility of quantitative chromatographic measurements. In contrast to low frequency pulsations which may affect the retention times and areas of different peaks in the chromatogram in different ways, high frequency pulsations are more like a uniform background signal which affects the whole chromatogram in substantially the same manner. The increase of the frequency of the pulsations is particularly advantageous when a detector is used which is very sensitive to flow pulsations, e.g., a refractive index detector.
The pumping apparatus according to the invention can not only be used in an isocratic solvent delivery system wherein the input of the pumping apparatus is permanently connected to only one solvent container such that only one type of solvent can be used in the chromatographic analysis, but also in applications wherein mixtures of solvents have to be produced, for example in gradient operation. For such applications, a known per-se mixing valve having a plurality of inputs coupled to different solvent containers can be connected with its output to the input of the pumping apparatus. The mixing valve is controlled such as to establish selectable connections to a solvent container, respectively, in order to produce the desired solvent mixture so that the selected solvent is drawn in when the first piston is retracted. Since the stroke volume is reduced at small flow rates, the amounts of liquid drawn in during each intake stroke for producing a specific mixing ratio are smaller than in conventional pumps. Due to the smaller packages of liquid drawn in, the pump according to the invention ensures a better mixing of the different solvents sucked in than known pumps. Consequently, an additional mixing chamber as it is used in prior art solvent delivery systems between the output of the pumping apparatus and the input of the separation column is either unnecessary or, at least, a much smaller mixing chamber can be employed so that the unwanted dead volume introduced by such a chamber is substantially reduced. Furthermore, faster gradient changes become possible.
According to the invention, the driving of the pistons can be accomplished by using any drive means which permits the adjustment of the stroke lengths of the pistons. According to a preferred embodiment of the invention, the pistons are coupled to ball-screw drives which translate the rotary motion of the spindles into a linear motion of the pistons. In that way, the stroke volumes can easily be changed by changing the angle through which the spindles are rotated during a pump cycle. Furthermore, a ball-screw drive permits to select any desired displacement/time function for the motion of the pistons during a pump cycle, for example a linear variation of the piston displacement as a function of time or a motion with a pre-compression phase during which a piston is accelerated for a short time. This flexibility is an advantage over prior art pumps which would require a new set of specially designed cams for each new displacement/time function for the piston motion.
The ball-screw drives may either be coupled via gears to a common drive motor, or each ball-screw drive may be coupled to a different drive motor so that an independent operation of the two pistons is permitted. If two separate drive motors are used, it is possible to precompress the aspirated solvent with the first piston before the second piston has finished its delivery stroke.
The transmission of the driving force to each piston can advantageously be accomplished via a ball which can move freely in a recess of an actuating element coupled to the rest of the drive means, e.g. a ball-screw-drive, with the ball contacting a piston holder to which the piston is fixed. Since there is no rigid connection between the drive means and the piston, tilt of the piston can be avoided, resulting in an increased lifetime of the seals of the pump chambers.
According to an embodiment of the invention, a damping unit for damping any remaining flow variations in the outflow of the pump is coupled to the output of the second pump chamber.
Subsequently, embodiments of the invention are explained with reference to the drawings.
FIG. 1 schematically shows a solvent delivery system for a liquid chromatograph incorporating the pumping apparatus according to the invention.
FIG. 1A is an alternate embodiment of the apparatus of FIG. 1.
FIG. 2 is a detailed view of the coupling between the piston and the drive mechanism of the pumping apparatus according to FIG. 1.
FIG. 3 is a graphical representation of the path travelled by the first piston in a pumping apparatus according to the invention plotted against time for two different stroke volumes.
FIG. 4 is a graphical representation of the stroke volume displaced by the first piston in a pump according to the invention plotted against flow rate.
FIG. 5 is a graphical representation of the frequency of reciprocation of the pistons in a pumping apparatus according to the invention and in a conventional pump having a constant stroke volume.
FIG. 6 is a graphical representation of the percent pulsation of the output flow in a pumping apparatus according to the invention and in a conventional pump having a constant stroke volume.
FIG. 7 is a graphical representation for gradient operation illustrating the change of the solvent composition as a function of time for a pumping apparatus in accordance with the invention and for a pump with a fixed stroke volume.
Referring to FIG. 1, there is shown a solvent delivery system according to the present invention for a liquid chromatograph. Capillary tubes 1a, 1b, 1c, and 1d are connected with one end to solvent containers represented by the letters A, B, C, and D, respectively, and with the other end to a mixing valve 2. The mixing valve 2 has an output capillary 3 which is connected to an inlet valve 4 of the first pump chamber. The mixing valve 2 can be operated such that its output capillary 3 is connected to a selected input capillary 1a, or 1b, 1c, or 1d to permit flow of a selected solvent to the first pump chamber. By appropriate switching of the mixing valve, a desired solvent composition can be generated. The switching of the mixing valve is accomplished by one or several solenoids (not shown) under the control of a control circuitry which is explained below in more detail. In the embodiment according to FIG. 1, the mixing valve is shown to have four input capillaries, but it is understood that a mixing valve having any number of input capillaries could be used.
The inlet valve 4 is an active valve which can be closed or opened by a solenoid 5 under the control of the control circuitry. Instead of the active inlet valve 4 according to FIG. 1, a conventional check valve could also be employed. An inlet capillary 6 connects the output of the inlet valve 4 to the input of the pumping system. The pumping system comprises two substantially identical pump units which are connected in series, each unit being designed as a piston pump. The first pump unit comprises a pump chamber 7 having a cylindrical inner bore 8 for receiving a piston and a corresponding sapphire piston 10 for reciprocating movement inside the cylindrical bore 8. The pump chamber 7 has an inlet bore 9 at its lower end through which liquid supplied through the capillary 6 can flow into the cylindrical bore of the first pump chamber. The inlet bore 9 is located such that it is closer to the bottom dead centre than to the top dead centre of the piston 10. The outer diameter of the piston 10 is smaller than the inner diameter of the bore 8 of the pump chamber so that liquid can flow in the gap between the piston 10 and the inner surface of the bore 8. A seal 11 is provided at the bottom of the pump chamber 7 for sealing off the chamber at the opening through which the piston moves into the chamber so that no liquid can reach the outside. The driving mechanism of the piston will be described below in more detail.
The pump chamber 7 has an outlet bore at its top through which liquid can leave the first pump unit. The outlet bore is connected via a capillary 12 to an outlet valve 13 which can be, for example, a conventional check valve. The valve 13 permits liquid to flow only in a direction away from the first pump unit and inhibits flow of liquid in the opposite direction. A capillary 14 connects the valve 13 to the inlet of the second pump unit. The second pump unit comprises a pump chamber 18 having a cylindrical bore 19 for receiving a piston, a lateral inlet bore at the same relative location as the inlet bore of the first pump chamber, an outlet bore at the top of the chamber and a sapphire piston 20 for reciprocating movement inside the bore 19 of the chamber 18. The chamber 18 is sealed off by a seal 21 to avoid that any liquid leaves the chamber through the opening through which the piston extends into bore 19. The aforementioned components of the second pump unit thus have the same design as the corresponding components of the first pump unit.
The outlet of the second pump unit is connected via a capillary 22 to a damping unit 23 which serves for damping any pressure and flow variations which might occur in the outflow of the second pump unit. According to a preferred embodiment, a high pressure damper of the type is used which is known from DE-PS 33 06 631. This damper comprises two chambers separated by an elastic partition, with the first chamber receiving the fluid to be damped and the second chamber containing a compressible liquid such as water and a solid ceramic block which compensates for the different coefficients of expansion of the compressible medium and the housing of the second chamber. An integral component of the damping unit 23 is a sensor for measuring the pressure of the delivered liquid.
The output of the damping unit 23 is connected via a capillary 24 to the subsequent chromatographic system (separation column etc.) where the separation of the substances to be analyzed takes place.
It is understood that in an alternative embodiment of the invention, the damping unit can be arranged between the two pump units such that the input port of the damping unit is connected to the outlet valve 13 and that its output port is connected to the inlet of the second pump unit. All the other components of the pumping apparatus as well as the operation of the apparatus would be the same as in the embodiment shown in FIG. 1.
The sapphire pistons 10, 20 of the two pump units are driven by using a ball-screw drive for each piston. The lower ends of the piston 10, 20 are attached to piston holders 25, 26, respectively, and the piston holders are coupled via balls 27, 28 and actuators 37, 48 to recirculating ball spindles 30, 31, respectively. Also provided are return springs 15 and 29.
The ball-screw drives 30, 31 are coupled to toothed gears 33 and 34, respectively. The gears 33 and 34 are mating and gear 33 is coupled to a third gear 32 which is fixed to the shaft of a drive motor 36. According to a preferred embodiment, the proportions of the toothed gears 33 and 34 are selected such that gear 34 performs two revolutions when gear 33 performs one revolution. A digital indicator 35 for the angular position of the motor 36 is provided which permits to precisely determine the position of the pistons from the transmission ratios of the gears and the ball-screw drives. Alternatively, as shown in FIG. 1A, a separate motor 36' may be coupled via gears 32' and 33' to piston 10, allowing an adjustment of the relative phase of the reciprocating motions of the first piston 10 and the second piston 20.
Details of the coupling between the piston holders and the ball-screw drives are now explained with reference to FIG. 2 which is a detailed view of a part of the first pump unit of the pumping apparatus shown in FIG. 1. An actuator 37 which is rigidly connected to the ball-screw drive 30 comprises a recess 38 for receiving a ball 27. The ball 27 is free to move in the recess 38. The top of the ball 27 contacts the piston holder 25 connected to the piston 10. The piston is guided by a guiding element 39. The guiding element 39 is mounted to a mounting element 40 which is connected to the pump chamber 7. A return spring 15 is connected with one of the its ends to the pump chamber and with its other end to the piston holder 25. The return spring 15 pulls the piston downwards when the actuator 37 moves downwards. When the actuator moves upwards, the ball pushes against the piston holder so that the piston 10 moves upwards. The driving of the piston via the freely moving ball 27 in combination with the guiding element 39 ensures that the movement of the piston is free of tilt, resulting in an increased lifetime of the seal 11.
In the following, the control circuitry of the pumping apparatus of the invention is described with reference to FIG. 1.
A system controller 41 controls the function of the pumping apparatus in response to inputs made by a user via a user interface 42 coupled to the system controller. The user interface 42 can be any known input device, e.g., a keyboard. The user may input via the user interface 42, for example, a desired flow rate or a desired solvent mixture or a desired solvent gradient.
A pump drive controller 43 is connected to the system controller 41. A control loop for controlling the movement of the motor 36 is indicated by block 44. The actual value for the position of the motor 36 to be used in the control loop 44 is provided from the angular position indicator 35 and the nominal value is provided from the pump drive controller 43.
Also connected to the system controller 41 is a gradient controller 45 which supplies control signals via line 51 to the mixing valve 2 dependent on a desired solvent gradient selected by a user via user interface 42. The control signals permit a switching of the mixing valve 2 such that liquid can flow from one of the solvent containers A,B,C, or D through the valve to the first pump unit. By selection of the time intervals during which such a connection to a specific solvent container is established, a desired solvent gradient can be produced.
An inlet controller 46 coupled to the system controller 41 controls the opening and the closing of the inlet valve 4 in coordination with the movement of the piston 10. The control signals are supplied to the solenoid 5 on a line 52.
The pressure of the delivered liquid is measured by a pressure transducer arranged in the damping unit 23. The analog output signal of the pressure transducer is supplied on a line 53 to an A/D-converter 47 by which it is converted into a digital signal. This digital signal is supplied to the system controller 41 from which it can be passed to the user interface 42 and displayed.
Subsequently, the operation of the pump is described in two modes of operation, respectively, namely in the isocratic mode and in the gradient mode.
In the isocratic mode, one of the solvent containers A,B,C, or D is permanently connected to the inlet valve 4 so that always the same solvent is delivered. This can be accomplished either by holding the switching state of the mixing valve 2 fixed at one position so that its output is permanently connected to the same solvent container, or, alternatively, by operating the solvent delivery system without a mixing valve, so that one of the containers A,B,C, or D is directly connected to the input valve 4 without an intermediate mixing valve.
Upon start-up of the solvent delivery system, first of all, the top dead centre of the movement of the first piston 10 is determined. Under the control of the control circuitry, the first piston 10 slowly moves upwards into the bore 8 of the piston chamber until the piston holder 25 abuts the lower end of the pump chamber 7. Once this end position has been reached, the piston 10 moves back a predetermined path length. This position of the piston is defined as the top dead centre and the corresponding angular setting of the motor 36 determined by the indicator 35 is stored as a digital value in the control circuitry. Thus, the top dead centre can always be accurately reproduced by providing the motor control loop 44 with this digital value as a nominal value.
After this start-up procedure, the pump starts with its normal operation. The inlet valve 4 is opened by the solenoid 5 under the control of the inlet controller 46 and the piston 10 moves down from the top dead centre, thereby sucking solvent into the first pump chamber. According to the present mode of operation, the stroke length, i.e., the distance the piston travels between its top dead centre and its bottom dead centre is dependent on the flow rate which a user has selected at the user interface 42. From the information about the desired flow rate passed from the user interface 42 to the system controller 41, the system controller 41 computes the corresponding stroke length using a predetermined mathematical relationship between flowrate and stroke length (or stroke volume, which is proportional to the stroke length). An example of such a predetermined relationship between flowrate and stroke volume is explained below with reference to FIG. 4. Although, in the present mode of operation, there is a predetermined relationship between the flow rate and the stroke volume, the control circuitry of the present invention yet permits to put the coupling between flow rate and stroke volume out of action so that a free selection of the stroke length or volume becomes possible.
Once the first piston 10 has travelled the stroke length determined by the control circuitry from the top dead centre to the bottom dead centre, the drive motor 36 is stopped and the inlet valve 4 is closed so that no more liquid can flow into the first pump unit. Then, the motor 36 is restarted, now moving in the opposite direction as before until it again reaches the top dead centre. Then, the sequence starts anew with the piston moving down from the top dead centre to the bottom dead centre. Since the two pistons 10 and 20 are rigidly coupled to each other via gears 33 and 34, the second piston 20 operates with a fixed phase difference relative to the first piston 10. This phase difference is 180 degrees. As a consequence of the 180 degrees phase shift, the second piston 20 delivers liquid when the first piston 10 sucks in liquid and vice versa.
Since the gears 33 and 34 have a ratio of their circumferences of 2:1 and the ball-screw drives 31 and 30 are identical, the first piston 10 moves twice the path of the second piston 20 at any angular step of the motor 36. As a consequence thereof, the stroke volume V1 of the first pump unit is twice as large as the stroke volume V2 of the second pump unit, i.e., V1=2*V2. During the expulsion stroke of the first piston, the second piston sucks in half of the volume displaced by the first piston and during the suction stroke of the first piston, the second piston delivers the volume sucked in in the preceding half-cycle. Thus during a complete pump cycle (suction stroke and expulsion stroke) the volume V1 is delivered to the output of the pumping apparatus. In the embodiment of FIG. 1, the output of the second pump unit is connected to the damping unit 23 which serves for compensating for the delay in delivery at the beginning of the delivery phase of the first piston.
The operation of the pump according to the invention is now further explained with reference to the diagrams in FIGS. 3 to 7. FIG. 3 shows a displacement-time diagram for the movement of the first piston 10, assuming a specified fixed flow rate. The horizontal axis is the time axis and the vertical axis is the axis for the displacement of the piston. The displacement-time diagram of FIG. 3 illustrates the preferred embodiment of the present invention that the paths travelled by the pistons are linear functions of time with two exemplary cases: in the first case, represented by the solid lines, the stroke length or stroke volume is twice as large as the stroke length or stroke volume in the second case, illustrated by the dashed lines. In both cases, the same amount of liquid is delivered within a specified time interval so that the resulting flow rates are identical. As can be seen from FIG. 3, the paths travelled by the pistons during the intake stroke or during the outtake stroke are linear functions of time, respectively, starting from the top dead centre (displacement=0), running to the bottom dead centre (maximum displacement), then returning to the top dead centre, and then repeating this sequence. The dashed curve has twice the frequency of the solid curve because the stroke path or stroke volume corresponding to the dashed curve is only half the stroke volume corresponding to the solid curve and the resulting flow rate is the same in both cases.
FIG. 4 shows an example how the stroke volume for the first piston 10 is varied with the flow rate of the delivered liquid. The relationship shown can be stored, for example, in the form of digital values in the system controller 41. It can be seen from FIG. 4 that, except for a small range of flow rates near zero, the stroke volume for the first piston is increased linearly with the flow rate, that means the plot of stroke length versus flow rate is a straight line. At very small flow rates below about 0,1 ml/min, the stroke volume is kept at a constant value down to zero flow rate. It is understood that the relationship plotted in FIG. 4 is not the only one possible but that various modifications thereto are possible, whereby it is preferred that the stroke volume is decreased when the flow rate is decreased.
In FIG. 5, the curve labelled "a" depicts the variation of the frequency of reciprocation of the pistons (pump frequency) with the flow rate assuming that the stroke volume is changed with the flow rate according to the function shown in FIG. 4. The pump frequency for each selected flow rate is determined by the system controller 41. The curve labelled "b" depicts the variation of the pump frequency with the flow rate for a prior art pumping apparatus having a fixed stroke volume of 100 microliters. Since, according to the invention, the stroke volume is changed with the flow rate, the pump frequency is a more complicated function of the flow rate than the straight line "b" of the prior art wherein the flow rate is increased by linearly increasing the pump frequency. The example according to FIG. 5 shows that for flow rates below 5 milliliters per minute, the pump frequency in a pumping apparatus according to the invention is larger than in the prior art pump. Since the pump frequency is larger, an remaining pulsations in the outflow of the pumping apparatus also occur with a higher frequency so that the ripple in the output signal of a detector coupled to the separation column has higher frequency than in prior art devices. Such an increase of the ripple frequency is advantageous with regard to accuracy and reproducibility of the chromatographic measuring results.
FIG. 6 illustrates the effect of a variable stroke volume on the pump pulsations. The horizontal axis of the diagram is the flow rate and the vertical axis of the diagram is the pump pulsation P in percent. The percent pump pulsation P is defined as P=100* (Pmax -Pmin)/Pmean wherein Pmax is the pressure in the delivered liquid when the second piston is directly before its top dead centre, Pmin is the pressure at the beginning of the compression phase of the first piston, and Pmean is the mean pressure during a pump cycle. The pump pulsation is defined in terms of pressure, but with the assumption of laminar flow of the liquid, this is equivalent to a definition in terms of flow rate. In FIG. 6, curve "c" depicts the percent pulsation for a pumping apparatus according to the invention incorporating a relationship between flow rate and stroke volume as shown in FIG. 4, and curve "d " depicts the percent pulsation for a prior art pump having a constant stroke volume of 100 microliters. It can be seen that the invention leads to a substantial reduction of the percent pump pulsation.
In the following, gradient operation of the pump according to the invention is explained. For gradient operation, a mixing valve 2 connected to different solvent containers A,B,C, and D is required. For generating a solvent gradient, the mixing valve 2 is controlled during the intake stroke of the first piston 10 such that a specified solvent container is connected to the pump input for a certain fraction of the whole stroke path of the first piston. This fraction is calculated in the system controller 41 from the desired mixing ratio of the different solvents. The following example is to illustrate this situation:
If the user desires a mixing ratio of the four solvents in the containers A,B,C,D of 20:40:30:10, the system controller 41 computes, taking into account the stroke length for the present flow rate, the positions of the first piston at which a connection to the respective solvent containers has to be established through the mixing valve. At a flow rate of 5 ml/min, for example, the aspirated volumes of the solvents A,B,C,D, respectively, would be 20 μl, 40 μl, 30 μl, 10 μl, respectively, during one pump cycle, because the total volume aspirated by the first pump unit during a pump cycle, i.e., the stroke volume, has to be 100 μl according to the relationship between flow rate and stroke volume shown in FIG. 4. At a flow rate of 0,1 ml/min, the same solvent composition is achieved for the aspirated volumes 4 μl, 8 μl, 6 μl, 2 μl of the solvents A,B,C,D, respectively, because the stroke volume at a flow rate of 0,1 ml/min is 20 μl (see FIG. 4).
In contrast to this latter example, a pump having a fixed stroke volume of 100 μl would, in order to produce the mixing ratio of 20:40:30:10 at a flow rate of 0,1 ml per minute, suck in during a pump cycle liquid packages of 20 μl, 40 μl, 30 μl, and 10 μl. Thus, the liquid packages sucked in by a pumping apparatus according to the invention are much smaller than with pumps having a fixed stroke volume, so that the invention permits a better mixing of the different solvents. Therefore, in particular at small flow rates, an additional mixing unit as it would have to be provided in a pump having the fixed stroke volume of 100 μl is not necessary in a pumping apparatus according to the invention.
Reference is now made to FIG. 7 which is a graphical representation for gradient operation of a solvent delivery system. The horizontal axis is the time axis and the vertical axis is the axis for solvent composition, e.g., the concentration of a specific solvent within a mixture of various solvents. FIG. 7 shows three curves e,f, and g. Curve "e" illustrates the ideal course of a linear gradient, i.e. a straight line. Curve "f" is the course for state of the art solvent delivery systems having a constant stroke volume of, for example, 100 μl. It can be seen that the solvent composition is changed in comparatively coarse (large) steps. Curve "g" shows the course for a solvent delivery system according to the present invention. The steps are about five times smaller than in the state of the art. Further linearization of this step function is achieved through the system dead volume and an (optional) mixing unit which, however, is not required at flow rates smaller than about 4 ml/min.
With regard to gradient operation, the pump of the present invention has the further advantage that the packages of the different solvents leave the pump in the same order as they have entered the pump (first-in-first-out principle). This is due to the fact that the inlets of the two pump units, respectively, are located close to the bottom dead centres and the outlets close to the top dead centres of the pistons.
In the embodiment of the invention described above, the two pump units are driven by a common motor via toothed gears so that there is a fixed phase relationship of the movements of the two pistons. According to another embodiment of the invention, each of the two pistons can be driven by a separate motor which can be controlled independently from each other. With these two independent piston drives, the pump can be operated such that the solvent in the first pump unit is first compressed before the second pump unit has finished its delivery cycle. In that way, any remaining pulsation in the outflow of the pump due to solvent compressibility can be completely eliminated so that a pulse damping unit 23 is no longer required.


There’s good news, bad news, and an annoying thing that happened with Eadon.
The good news is that the yarn arrived on Thursday to finish Eadon, I’m now done with all the knitting of it, and it’s been blocking since Saturday morning. The bad news is that the skein of yarn that arrived for me to finish it was a tiny bit darker and much more of a solid then the rest of the yarn. I’m hoping once it’s all sewn up it won’t look horrible. The annoying thing that happened when I started working on the shoulder seam part of the second sleeve was that I realized I didn’t bind off enough stitches on the first sleeve and I had to rip it back Friday night to fix it. At least I realized it, wasn’t too bad to fix, and didn’t take long! I started seaming Eadon Monday night, but it’s taking me a while to do. The way the prices go together is different from every other sweater I’ve seamed up until now. I’ve started seaming parts of it only to not like the way it’s going and starting over again. I’ll get it done tonight, though. Only one more sleeve to sew in!
Since I finished knitting Eadon Saturday morning just before we went out of town for the weekend, I decided to try and work on the socks I have on the needles. Sadly, that hasn’t really worked out very well (I’m glad I brought a non-small-needle project with me, more on that below). Small needles still really bother my wrists and I can only knit a few rows before having to put it aside. No real progress on socks to show right now. Knitting Eadon didn’t bother my hands or wrists at all which makes me think it’s the needle size that’s doing it. I want to get at least one of the pairs off the needles, but after that I think I’ll take a break from knitting anything on small needles for a while. At least there’s always plenty of other things I can knit!
Last week sometime I got this idea in my head that I needed to knit a Rhinebeck sweater. Yes, I’ve got a sweater I’m nearly done with, but it wasn’t knit with Rhinebeck specifically in mind, so my brain reasoned that I should start something new with about a month to go until Rhinebeck. I was looking at DK and sport weight patterns initially. Even decided on two to pick from. One out of the yarn I bought at Rhinebeck last year and one out of the yarn I bought at the Spring Fling last year. Then I realized this was all rather crazy talk. I’d be stressing myself out trying to do this on a deadline when I’ve spent the summer working on deadline projects for Camp Loopy and haven’t really enjoyed it. So, I took a step back to think about it.
I looked at my stash. No worsted or bulky weight of yarn in a sweater quantity. I looked at sweaters I’ve knit that no longer fit me since I’ve lost over 60 lbs since I knit some of them. Even after I lost about half of the weight, I think I was still knitting to those heavier measurements and some things ended up not fitting that well. The difference in measurements wasn’t that big. I think I was just sizing up the way I did before and ending up with oversized sweaters rather than ones that were fitted. Anyhow, I now have a pile of sweaters that look like I’m swimming in them when I put them on and it makes me sad. While looking at my stash and my finished sweaters, I saw Seneca. I knit this earlier this year. When I finished it, it did end up a little too big. I loved the yarn and the pattern, though, and when I started losing more weight, I decided I would re-knit it later.
I’m still about 20 lbs from my goal, but it’s later enough and I decided I’m close enough to goal that I can reasonably start re-knitting Seneca with Rhinebeck in mind. Last week after deciding this, I frogged the Seneca I finished in February. After finishing Eadon on Saturday, I started Seneca. I’m knitting a smaller size, still adjusting for the gauge like I did the first time around. This time it should end up about 40″ across the chest, which is a bit less then my current chest measurement. It gives me some room to “shrink” into it! Even if I don’t end up losing any inches in my bust, I think it will still fit well with a bit of negative ease. I’ve managed to make my way through the cable on the bottom of the body and I’m currently working on the waist decreases.
The last two years I’ve gone I’ve had a new sweater to wear, one that was finished with the intention of wearing it to Rhinebeck. Earlier this year I had planned to not knit a sweater for Rhinebeck because I had taken a break from sweaters since I was losing weight (and still have a way to go, so I still am). I may or may not have Seneca done and if I don’t, I’ll probably wear Eadon along with the hat and mittens I plan on making. I think it’s kind of fun to have something new to wear that was made/bought just to wear at Rhinebeck, though I know a lot of people don’t bother with new things and wear things they’ve knit/crocheted without Rhinebeck specifically in mind.
Planning on going to Rhinebeck this year? Knitting or crocheting anything specifically for it?
One thought on “Sweaters, Weight Loss, and Rhinebeck”


Demystifying Big Red
The TEUPEN TL 156AX, or “Big Red” as it is affectionately known, is the state-of-the-art aerial lift machine that takes center stage of the Oculus floor once a year. The Oculus is a unique structure that requires a specialized crane to get to its hard-to-reach spaces.
We spoke to the engineers to learn more about the machine and shed some light on the annual tradition.
What is Big Red?
Big Red is a custom-built machine designed to reach interior spaces of the Oculus for certain maintenance and operations functions. It was created to inspect 60 exhaust fans located at the top of the Oculus. Every year, each fan must pass inspection and the engineers ensure that nothing has been trapped in the fans. If you have ever lost a balloon in the Oculus, the engineers have most likely discovered it in the fans.
How was Big Red named?
When Big Red was brought into the Oculus, engineers were asked to submit name suggestions for it, and the winning name was “Big Red” which has followed the machine since it was brought here.
Big Red Specs
- Its arm can reach the highest point of the Oculus at approximately 160 feet.
- It can extend over 50 feet horizontally with its legs.
- It weighs 30,000 pounds.
How does it operate?
Comprehensive safety control systems, onboard diagnostics and trained personnel ensure safe operation of the machine. Personnel must pass emergency repel training to operate it. One of the advantages of this machine is its safety features, including a one- or two-person cage and harness system, as well as a fall arrest system that ensures the operator is secure. This machine is also designed with stability in mind, with a 4-point leveling system that keeps the machine steady.
To move across the marble floor from its resting area, a Duradeck floor protection system is placed along its path of travel and Big Red glides across it.
Big Red helps maintain the iconic structure of the Oculus while making it easier and safer for workers to access difficult-to-reach areas. If you visit the Oculus during February, stop by, and take a look at it either in action during the evenings and overnights, or resting on the Oculus floor during the day. During other parts of the year, you can find it in its collapsed position and stationed on the south side near the staircase towards the PATH trains.


text:
Room Booking by E-mail
Please contact us by e-mail at: email@example.com!
Our Special Rates and Promotions
Please check our special rates by e-mail at: firstname.lastname@example.org
Our rooms are designed to transport you into an environment made for leisure. Take your mind off the day-to-day of home life and find a private paradise along limestone rocks of Tam Coc area.

domain: travel


text:
Brace yourself for another royal baby!
Kensington Palace has confirmed that Meghan Markle and Prince Harry are expecting their first child, due next spring. The news comes nearly five months after their wedding on May 19.Read More >>
Ariana Grande and Pete Davidson are dunzo as a couple, and their engagement has officially been called off ... TMZ has learned.
Sources close to the former couple tell us AG and PD split this weekend, with both parties acknowledging that it simply was not the right time for their relationship to take off. We're told the two still have love for each other, but things are over romantically.Read More >>
The Tigers entered Friday's home game against Sun Valley with a record of 7-0, having outscored their opponents 314-89.
Buoyed by a remarkable 56-point second quarter, Washington did something no high school team has done in recent memory, hitting the century mark in a 101-6 victory.
The Tigers scored 17 points in the first quarter and 21 in the third, going up 94-6 after three quarters.Read More >>
Selena Gomez was hospitalized twice in the last 2 weeks ... and the second time she suffered what sources called an emotional breakdown ... she's now at a mental health facility for treatment.
Multiple sources tell TMZ, the 26-year-old singer was at her Studio City, CA home the last week of September when the first emergency hit. We're told she was despondent and emotional over an alarmingly low white blood cell count in the wake of her kidney transplant. Our sources say a family member drove her to Cedars-Sinai Medical Center in L.A.Read More >>
It was a record-breaking night for Taylor Swift at the American Music Awards.
Not only did the pop superstar open the show with a fiery performance of “I Did Something Bad,” but she went on to win four awards, breaking Whitney Houston’s record for most AMA wins by a female artist. She took home the trophies for Tour of the Year, Favorite Pop/Rock Album for "Reputation," Favorite Female Artist Pop/Rock and Artist of the Year -- bringing her career total to 23 AMAs.
In addition to breaking a record, Taylor continued to break her silence on politics. After getting political in an Instagram post over the weekend, Taylor used her acceptance speech for Artist of the Year to encourage people to vote.Read More >>
Mike "The Situation" Sorrentino is planning on a life of luxury when he gets home from prison ... Exhibit A -- his wedding registry.
The Situation is marrying college sweetheart Lauren Pesce, November 1 (he has 60 days to turn himself in) and they're asking friends and family to spare no expense when it comes to wedding gifts.
Only the best for Mike when he's done with his 8-month sentence for tax evasion ... the Sorrentinos want a $550 blender, $500 juicer, $380 dutch oven, $375 knife set and $180 pasta press ... 'cause he'll be tired of those cheap prison meals by the time he's a free man again.Read More >>
After years of silence and growing frustration from her loyal fanbase, Taylor Swift has finally spoken up about her political views by endorsing a Senatorial candidate in her home state of Tennessee.
More specifically, Swift is patently not endorsing Republican candidate Marsha Blackburn, per a scathing Instagram post that went up late Sunday night, just after she'd wrapped her US tour. Blackburn is one of the two candidates running to fill the seat currently held by Sen. Bob Corker.Read More >>

domain: celebrity


text: Our fabric of this week is blue shweshwe fabric. Blue was one of two of the original colours that this South African print fabric was available in. There are now of course many colourful colourways that have been added to what is available. This colourway consists of just two colours; blue and white. Nice and simple. The beauty of shweshwe fabric and the way it is produced is that it lends itself so well to mixing and matching, especially in the same colourway. So whether you are dressmaking or quilting or working on some patchwork, you have so much room to let your imagination run wild. Check out our current selection of blue shweshwe. Just click on the individual image to take you to the product page. We will continue to grow our selection of blues as we go along! Blue shweshwe fabric for Quilting Shweshwe is a very popular choice for quilters. It is 100% cotton, washes well, great to sew and is available in a variety of designs and colourways. If you are more of a quilter or working on smaller craft projects, you can check out our fat quarters instead. Are you a fan of shweshwe fabric? Have you made anything with it? Do drop a comment or share your project with us. Happy sewing!

domain: design


text:
And now here we are again. And look like this is what it will be like for the foreseeable future.
Reports say that “all customers” should expect to be without power a total 14 days – 2 weeks time – out of this summer. Some 21 million Californians stand to be directly affected:
All customers, including homes, hospitals, oil refineries and airports are at risk of losing power at some point this summer because a majority of electric generating stations in California use gas as their primary fuel. In April, millions of electric customers in Southern California were warned they could suffer power outages on up to 14 days this summer due to the closure.
Unlike some other gas transmission systems that can store large amounts of so-called linepack gas in pipelines, like PG&E Corp in northern California, SoCalGas cannot function with only pipeline or storage supplies.
Planned rolling brownouts have been done on a regular basis in Southern California since the days of Enron and the California energy crisis of 200o-2001, but the situation is getting more dire.
Isn't recurring blackouts a problem in 3rd world countries?

domain: news


text:
Your Views, July 2
A sinful decision
Before the Civil War, the U.S. Supreme Court held in Dred Scott v. Sandford that free black descendants of slaves were not Americans or entitled to access to the courts. Three-quarters of a century later, Chief Justice C.E. Hughes confessed this evil decision was “the Court's greatest self-inflicted wound.” About 30 years after Dred Scott, the court ruled that Native Americans were not citizens either, despite passage of the 14th Amendment, which stated, “All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States. ...” Forty years later, Congress admitted the inanity of the decision and enacted the Indian Citizenship Act. During World War II, the Supreme Court said the president could order innocent Japanese-Americans into concentration camps. Sixty-four years later, the court expressly repudiated this immoral decision.
Now in Trump v. Hawaii, the Supreme Court admits but ignores the president's express un-American and vulgar language to rule a religiously discriminatory government travel policy is legal. Eventually, this decision will be found as evil, inane and immoral. As Justice Sonia Sotomayor wrote in dissent, "History will not look kindly on the court's misguided decision today, nor should it." We hope the government will not take 40 to 75 years to confess its sin.
Andrew Tevington, Oklahoma City
U.S. Rep. Maxine Waters encouraged people to be aggressive when confronting conservatives. Instead of holding her responsible for her words, the reporting pointed at President Trump as the cause of the current hostility and conflict, saying he began this trend with the way he conducted his campaign and faced his competitors. Wait a minute. It was former President Obama who said I was clinging to my Bible and my guns. It was Michelle Obama, after her husband's election, saying, “For the first time ... I am really proud of my country.” And of course, it was Hillary Clinton who put me in that basket of “deplorables.” Pretty aggressive words, all.
As I stood in line to vote last week, a young woman ahead of me wore a tank top with “Resist” inscribed across it. Isn't that the slogan embraced by Democrats after Trump's election? I understand that Trump was a Democrat until 1987, relapsing from 2001-2009. Is it possible he's employing the tactics used by the left against them, and that is the real cause of their rage?
Debby Cave, Oklahoma City
Global warming causes
Robin Patten (Your Views, June 27) claims global warming is the cause of our heat. It can't be proven that Oklahoma's heat increase is tied directly or only to global warming. The United States has done more than any country to reduce its greenhouse gas (GHG) output. The problem is other countries, like China and India. They each have four times the population of the U.S. They have no intention to reduce or even slow their increasing output of GHG. Humans expel carbon dioxide and cows produce methane. Both are GHGs. Since 1900, the human population has risen from 1 billion to 7 billion and the cow population has tripled. Until China, India and others change their output of GHG global warming will rise, no matter what the U.S. does. Solutions? Recycle, eat less beef and stop supporting China and India until they start reducing their GHG output.
There is proof, however, that wind farms cause weather pattern changes around them (Scientific American, February 2014). By removing energy and redirecting wind from the atmosphere there is less to build storms. Fewer storms equals less rainfall and less cloud cover, which equals less surface cooling. This is why droughts have appeared near these farms.
There are many factors causing global warming.
Don Douglas, Oklahoma City
Send letters to email@example.com or to Your Views, P.O. Box 25125, Oklahoma City, OK 73125. Word limit is 250. Include a postal address and telephone number. For other guidelines, go to www.newsok.com/voices/guidelines or call (405) 475-3205.

domain: politics


It amazes me how quickly the Tribune rushes to castigate Democratic leaders in Springfield for the pension crisis. Why, in the editorial Friday, did the Tribune stop at 2003, when the pension crisis predated that by decades?
The Tribune editorial board could have cited the lack of enforcement of RAMP when Jim Edgar was governor and the GOP controlled the legislature. The Tribune could have cited the 1980s, when Republican Jim Thompson was governor and the Democrats controlled the General Assembly. The Tribune could have gone as far back as the Dwight D. Eisenhower Administration, a period of 60 years in which both Republicans and Democrats held power in Springfield, yet it did not.


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Teaching Students About Behavior Conditioning
Behavior conditioning is an essential concept in psychology, which deals with the way in which organisms learn and modify their behavior through stimuli and consequences. As educators, understanding behavior conditioning principles can help optimize classroom management and provide a more conducive learning environment for students. This article explores the different aspects of behavior conditioning, its applications within an educational setting, and different strategies that teachers can employ to teach students about this fascinating topic.
Understanding Behavior Conditioning: Classical and Operant Conditioning
There are two primary types of behavior conditioning: classical conditioning and operant conditioning.
This type of learning occurs through the pairing of a neutral stimulus with an unconditioned stimulus that naturally elicits a response. The classic example is Pavlov’s dog experiment, in which dogs were conditioned to salivate at the sound of a bell through repeated association with food. In time, the bell alone would elicit the salivation response.
Operant conditioning is about learning through consequences. In this type of learning, behavior is strengthened or decreased based on reinforcements or punishments. There are four types of contingencies:
a) Positive reinforcement: Adding something pleasant to strengthen a behavior
b) Negative reinforcement: Removing something unpleasant to strengthen a behavior
c) Positive punishment: Adding something unpleasant to weaken a behavior
d) Negative punishment: Removing something pleasant to weaken a behavior
Teaching Strategies for Behavior Conditioning Principles
Here are some methods that educators can implement to teach students about behavior conditioning:
Demonstrations and Experiments
Participating in hands-on activities can give students a better understanding of the principles at play. Teachers can facilitate live demonstrations or design simple experiments that showcase how classical or operant conditioning works.
Linking subject matter to students’ experiences can make concepts more relatable and easier to grasp. Teachers can encourage students to think of real-life examples of behavior conditioning, such as training pets or reacting to their phone notifications.
Engaging students in group activities that require them to apply their knowledge of behavior conditioning will reinforce their understanding of the topic. Activities can range from role-playing scenarios to creating visual representations of different conditioning processes.
Discussion on Ethical Implications
Initiating a discussion about ethical considerations surrounding the use of behavior conditioning, especially in operant conditioning, can encourage critical thinking and reflection among students and help them better understand the complexities involved.
Encouraging Research and Further Exploration
Empower students to explore various sources of information, including research articles, books, and informative videos, to gain a deeper understanding of behavior conditioning principles and how they apply to diverse aspects of life.

domain: psychology


text:
Truth, Peace, Kindness & Forgiveness...
July 14, 2007 12:01pm CST
These are the four basic noble qualities of human character that we know. For harmony and wellness in our socity, we all must culture these, irrespective of country. And above all, as we grow old day by day, we all must practise truth, peace, kindness and forgiveness ourselves. This will also remain as an illustration for the new generation. Please discuss your opinion.
2 people like this
17 Jul 07
Nowadays the need of the hour is Honesty in India.Because corruption is eating away the moral fabric of our Indian society.We have to address this issue as early as possible.We have to cleanse our political system in order to wipeout the corruption.BUT HOW TO DO IS A QUESTION MARK ?

domain: sociology


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Sri Lanka Ecommerce Table of Contents
Ecommerce industry in Sri Lanka has created a boom in the country's economy. The country's economy is growing at an impressive rate, especially in the field of information technology and tourism. In response to this, the government has made many developmental moves to improve infrastructure, boost nationalization and increase the country's capability in international markets. With these efforts, the Sri Lankan e-commerce market will continue to grow and take off. < /p>
The evolution of the internet has brought about some remarkable changes in the field of ecommerce in Sri Lanka. Sri Lanka was one of the first countries to introduce a free e-commerce platform to the world. Since then, it has grown rapidly and is now one of the leading countries in the world when it comes to ecommerce. Over the last few years, Sri Lanka has experienced rapid growth in terms of its ecommerce business. It has attracted international investment in terms of setting up of electronic data processing and web development.
Sri Lanka had an average internet user population of around 6.5 million as of July last year, about 25% of the total population. Despite being a rapidly developing country, the internet industry has still been getting much-needed funding over the past decade. In this context, the government has taken major steps to monetize the available resources, infusing greater capital investment in the sector, opening several international ecommerce portals on various popular search engines, and attracting internet giants like Google and Yahoo to host their Sri Lankan servers. Although the Sri Lankan government has also taken essential steps to improve the delivery of ecommerce solutions, they have failed to make much impact as the local players in the market lag behind significantly.
Even though the Sri Lankan government is taking vital measures to monetize the available resources in the market, there are still chances for the country to make more progress. In addition, Sri Lanka's weak economy and poor infrastructure hinder the government in releasing the capital investment required in the sphere of commerce. As a result, there is still no guarantee that ecommerce will really take off in Sri Lanka. However, with the right kind of strategies implemented by the authorities and sustained perseverance from the private players in the market, Sri Lanka is likely to see a significant improvement in the near future. Besides, there are several initiatives taken by the Sri Lankan government and civil society to improve the conditions of its ecommerce sector, including the recent banning of the sale of alcohol within two hours of closing, restricting alcohol advertising, and encouraging online payment.
One of the key developments has been the establishment of an Information Technology Promotion Board, or IITB. This board works to promote and improve the Sri Lanka information technology sector. It also develops educational programs for professionals, public administrators, students, and business owners to improve management skills. These educational programs also help improve the country's ability to develop digital technologies.
The government has also set up several national e-commerce frameworks to promote competition and create more consumer demand. For instance, the Information Technology Authority regulates all electronic and data communication businesses, such as telecommunication companies and internet service providers. The Sri Lankan Electronic Commerce Agency regulates all electronic and data-commerce activities in the country. The Communication and Information Technology Regulatory Agency regulate all aspects of the information technology sector of the country. Finally, the Controller of Customs and Border Protection manages all customs and border protection activities.
Another notable initiative taken by the Sri Lanka government is encouraging e-commerce players to set up shop in strategic areas throughout the country. For instance, the Government of Sri Lanka has issued a strategic plan to promote e-commerce presence in rural communities. Additionally, the government is encouraging state-owned enterprises and other large businesses to establish e-commerce presence in the agricultural sector. In this way, not only do these businesses get a wider customer base, they also create jobs in the agricultural sector, thereby supporting the Sri Lankan economy.
Although the Sri Lanka e-commerce industry has shown promising growth and is anticipated to continue to do so in the future, the country still faces several hurdles that it has to address on its way to becoming a developed online market. It is important for the country to address the problems of disparity in internet access. Currently, there are over 1.4 million broadband users in the country, which makes accessing the World Wide Web through any source a challenge. Sri Lanka is expected to improve its internet availability in the near future.
Another important challenge facing the e-commerce market in Sri Lanka is the lack of adequate infrastructure and trained manpower to support the growing online market. There are some states that still lack basic communication facilities and electricity among other essential amenities, which hinder the accessibility of the online market for buyers. However, this should not deter businesses from expanding their operations as many people in the rural regions still have access to telephones and electricity and also have a regular need of items like food and fuel for daily consumption.
The lack of adequate infrastructure also restricts electronic and communication products from being imported into the country, but this should not deter businesses from selling their goods online. There are several distributors in the country that allow the suppliers to sell their products at higher prices, which encourages local production rather than importing products from foreign producers. This aspect also encourages consumers to patronize local products and Services, thereby increasing the demand for the Sri Lankan product and Services. Moreover, there are several online directory services available which provide details on all the electronic and communication equipment manufacturers based in Sri Lanka.
Another challenge faced by the e-commerce industry in Sri Lanka is the slow process speed of orders. E-Commerce websites usually incur higher costs for delivery and processing, but if these costs are reduced to a certain level, then this can boost the revenue of an e-commerce website significantly. Rapid technological advancements have also facilitated the process of buying and selling. Payments can be made using Credit Cards or PayPal. There are several other methods such as Money Transfer, Debit Cards and Local Area Networking (LAN) that have become popular in the recent years.
Scroll down to read our indepth Ecommerce Platforms guide. What you should know, Ecommerce Platforms features, price plans and support. Pros and Cons of Ecommerce Platforms as a ecommerce, everything is explained below.
Shopify is a software company that specialises in ecommerce software for small to enterprise level businesses.
Shopify is listed as the best ecommerce software related to Ecommerce Platforms. Shopify was founded in 2006 in Ottawa, Canada and currently has over 6,124 employees registered on Linkedin.

domain: economics


text:
Casale has announced that it will redesign its ammonia converter currently in operation at a Yara-operated fertilizer plant in Herøya, Norway.
The existing plant will be converted by replacing the current hydrogen production process using liquefied fossil gas with green hydrogen based on renewable energy. By doing so, Yara will be able to create emission-free ammonia.
As part of this initiative, Casale is committed to applying its own technology, including the design of all-new ammonia converter internals. In addition, Casale designs its reactor in order to allow the synthesis loop of the Herøya plant to be able to operate initially with the traditional source. After the decarbonization of the plant, the Casale design of the reactor will allow the synthesis of ammonia to switch to the new source of green hydrogen without any additional intervention.
In this first stage of decarbonization, the plant will produce enough hydrogen equivalent to 20,500 tpy of green ammonia, which turns into 60,000 to 80,000 t of non-fossil green mineral fertilizer.
Read the article online at: https://www.worldfertilizer.com/project-news/23022022/casale-to-design-new-ammonia-converter-for-yara-facility/


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Composition characteristics of low alloy structural steel, JIS SMA400AW atmospheric corrosion resisting steel: (1) Low carbon: the carbon content of low alloy structural steel is less than 0.20% due to the high requirements of toughness, weldability and cold formability. (2) The alloy elements such as manganese are added. (3) The addition of Nb, Ti or V and other auxiliary elements: a small amount of Nb, Ti or V forms fine carbides or carbonitrides in the steel, which is beneficial to obtain fine ferrite grains and improve the strength and toughness of low alloy structural steel. In addition, adding a small amount of copper (≤ 0.4%) and phosphorus (about 0.1%) can improve the corrosion resistance. The addition of a small amount of rare earth elements can remove sulfur and gas, purify the steel, and improve the toughness and process performance of low alloy structural steel.
asme sa514 gr J alloy steel sheet element composition%C: 0.12-0.21, Si: 0.20-0.35, Mn: 0.45-0.70, P max.: 0.035, S max.: 0.035, Mo: 0.50-0.65, B: 0.001-0.005The mechanical properties in thickness (mm)T≤65Yield strength (≥Mpa): 690Tensile strength (Mpa):760-895Elongation in ≥,%: 18
Analyze the advantages and disadvantages of the products against the competitive JIS SMA400AW atmospheric corrosion resisting steel products. Understand the industry situation and future trend. Understand the product brand positioning appeal point, focus on the crowd and development direction. Understand the layout of each market area, and form a big strategic layout view. Understand the basic operation and assessment standards of work responsibilities. Understand the situation of the cooperative customers.
To provide customers with the most satisfactory service and realize the win-win of economic and social benefits, our company promises to provide excellent JIS SMA400AW atmospheric corrosion resisting steel products in this bidding, and in line with the attitude of being serious and responsible to customers, before sending goods to users, the JIS SMA400AW atmospheric corrosion resisting steel technical personnel shall confirm that there is no fault in the equipment before sending goods to users, and then send goods and products to users, and formulate the following service terms.


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AOL and Barclays have “won” the Uptime Institute’s annual Server Roundup by removing the highest number of obsolete servers from their respective data centers. (AOL, for its part, won the contest for the second year in a row.)
AOL decommissioned 8,253 servers in 2012, resulting in gross savings of almost $3 million from reduced utility costs, maintenance and recovery of asset resale/scrap. The financial services firm Barclays removed 5,515 obsolete servers in 2012, saving $3.4 million in annualized savings in power alone, and a further $800,000 in hardware maintenance.
Uptime Institute’s Server Roundup annual contest was introduced in October 2011 to raise awareness about the removal and recycling of “comatose” and obsolete IT equipment as a way to reduce data-center energy use. The idea, of course, is that obsolete servers simply aren’t as efficient as modern hardware, and waste energy and resources as a result.
But the contest doesn’t really factor in other factors that might affect server use, such as downsizing. AOL’s “walled garden” once dominated the Internet, and it’s unclear how many decommissioned servers helped with that particular effort. (Believe it or not, AOL dialup still contributed $230.8 million to AOL in the fourth quarter of 2012—a whopping 38 percent of its revenue.) Last year, AOL decommissioned nearly 10,000 servers and saved over $5 million; the runner-up, NBC Universal, only removed 1,090 machines.
“Lots of companies have been downsizing IT footprints and getting smarter about meeting IT demand, but not all of them are being smart about decommissioning the outdated equipment,” Matt Stansberry, director of content for Uptime, wrote in an email. “A lot of it is still sitting on the raised floor, or idling in a test-dev lab.”
According to industry estimates, around 20 percent of servers in data centers today are obsolete, outdated or otherwise unused. Uptime estimates that decommissioning one rack unit of servers can result in a savings of $500 per year in energy costs, plus an additional $500 in operating system licenses and $1,500 in hardware maintenance costs.
And then there’s the performance aspect: a server that may have cost $100,000 seven years ago, took up half a rack of space and required a couple of kilowatts to run is now absolutely crushed in compute performance by a modern $5,000 blade server, noted Paul Nally, a director at Barclays.
“The purpose of Server Roundup is to highlight what should be a routine activity–removing obsolete hardware from the data center–and moving it to the forefront of the conversation,” Matt Stansberry, director of content and publications at Uptime Institute, wrote in a statement. “We want to inspire participation and healthy competition to improve data center efficiency. Past efforts around data center efficiency have focused on the facilities infrastructure and PUE, and those efforts have hit a plateau. The future of data center efficiency gains will depend on engaging the IT professionals to take bold, new steps.”
TDBank, McKesson and Sun Life Financial also were named as finalists. TDBank removed only 513 servers, but received notice for recycling all of them within a 110-mile radius. McKesson pulled 586, saving $734,000, while Sun Life removed 387 servers, which Uptime estimated at an $8,800 savings per month.
Somewhat ironically, Uptime’s awards were handed out the same day as TSO Logic released a new software solution designed to power down unused hardware. However, TSO said its TSO Power software solution was designed for usable hardware that the data center would eventually need when it returned to peak load.


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Boston, MA, 06/28/2013 (financialstrend) – The share prices of Canadian Solar Inc. (NASDAQ:CSIQ) had been traded in the price range of $10.20 and $11.34 per share on Thursday. The share price of the company had gradually advanced by 9.50 percent more than the previous day. The share price of CSIQ has made a changes in the 52 week high value $11.34 per share and 52 week low value $1.95 per share.
Canadian Solar Inc. (NASDAQ:CSIQ) is a manufacturer of solar wafers cells by developing and designing the solar module products which is used for various purpose and convert sunlight into electricity. Products of the company includes a wide range of residential, industrial and commercial solar power generation systems and the company is also involved in building the standard solar modules by general specifications. It also produces and designs products based on orders to fulfill its customers’ requirements and specialty solar modules.
Canadian Solar Inc. (NASDAQ:CSIQ) at the end of March had four portfolio as hedges. The investors must be aware and of clear preparation for a decrease in hedge fund interest recently. At the end of the last quarter Canadian Solar Inc. (NASDAQ:CSIQ) database was having a six hedge fund positions. There are lot of reasons to cut the shares of the company and reduce down the stock market universe was by bullish insider trading activity.
The market capitalization value is nearly 477.26 million and institutional investors share’s value is about 15 percent. The Canadian Solar Inc. (NASDAQ: CSIQ) had a trading volume as 8.30 million and the average volume as 3.40 million per day on Thursday. The company presently holds outstanding share values as 43.16 million on Thursday.
This report is for information purposes only, and is neither a solicitation or recommendation to buy nor an offer to sell securities. Financials Trend is not-a-registered-investment-advisor. Financials Trend is not a broker-dealer. Information, opinions and analysis contained herein are based on sources believed to be reliable, but no representation, expressed or implied, is made as to its accuracy, completeness or correctness. The opinions contained herein reflect our current judgment and are subject to change without notice. Financials Trend accepts no liability for any losses arising from an investor's reliance on the use of this material. Financials Trend sometimes gets compensated up to one hundred and fifty thousand dollars per month for featuring particular stocks. See site disclaimer for complete compensation. Financials Trend and its affiliates or officers currently hold no shares of these stocks. Financials Trend and its affiliates or officers will purchase and sell shares of common stock of these stocks, in the open market at any time without notice. Financials Trend will not update its purchases and sales of these stocks in any future postings on Financials Trend's websites. Certain information included herein is forward-looking within the context of the Private Securities Litigation Reform Act of 1995, including, but not limited to, statements concerning manufacturing, marketing, growth, and expansion. The words "may", "would," "will," "expect," "estimate," "anticipate," "believe," "intend," " project," and similar expressions and variations thereof are intended to identify for ward-looking statements. Such forward- looking information involves important risks and uncertainties that could affect actual results and cause them to differ materially from expectations expressed herein. *Financials Trend does not set price targets on securities. Never invest into a stock discussed on this web site or in this email alert unless you can afford to lose your entire investment.

domain: finance


text:
People who fail to pay tolls at the Dartford Crossing will have to pay a fine of
up to £105, it has been revealed. The Highways Agency is consulting on how it will implement fines once toll booths are removed in 2014.
Concerns have been raised that plans for cameras to replace toll booths at the Dartford Crossing could leave motorists with huge fines.
Motorists will be fined £105 if they fail to pay tolls at the Dartford Crossing under plans revealed by the Highways Agency.


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By Bear Grylls
Contributore note: David Cooper (Foreword)
'No you possibly can fail to be gripped via his heartfelt pleasure and emotion over what was once the journey of a lifetime.' Independent
At the age of twenty-three, undergo Grylls grew to become the youngest Briton to arrive the summit of Mount Everest. At severe altitude early life holds no virtue over adventure, and it truly is often said that more youthful climbers have extra hassle dealing with the hostile results of climbing. however, purely years after breaking his again in a freefall parachuting twist of fate, undergo Grylls overcame critical climatic conditions, fatigue, dehydration and a final minute disease to face on most sensible of the world's maximum mountain. Facing Up is the tale of his event, his braveness and humour, his friendship and religion.
'Bear's story is via turns, hilarious and horrific.' day-by-day Telegraph 'Written with fresh humility, it is a rapidly instructed account no longer of conquering Everest, yet of realising its power.' day-by-day Mail 'He writes convincingly of worry and doubt. this can be a decent and compelling story.' Ranulph Fiennes
Quick preview of Facing Up: A Remarkable Journey to the Summit of Mount Everest PDF
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Extra info for Facing Up: A Remarkable Journey to the Summit of Mount Everest
The path of bootprints left within the slush of the day gone by afternoon had now frozen reliable, and confirmed us the direction. The entry-point was once marked with a bamboo cane that the Sherpas had left. I seemed again at Base Camp, and will see the smoke of the juniper nonetheless smouldering away. I was hoping the prayers could paintings. We have been the 1st Western climbers to be getting into the Icefall this yr. to this point merely the Sherpas were into her depths. We sat at the ice on the backside, with jagged pinnacles emerging up above us on both sides. because the Icefall flattens at its finish, it fluctuates alongside, rolling in those crests of contorted ice. Hidden among the pinnacles, clear of the view of Base Camp, we sat and commenced for the 1st time in months to place our crampons on. A combined feeling of pleasure and trepidation flooded my physique. eventually we have been starting the duty that were a dream for thus lengthy. I yearned simply to start, to get my tooth into it. I felt that when the bit used to be among my tooth, then it'd be more straightforward to carry directly to. yet with it got here that fearful, ill feeling. forward used to be the unknown. We started to weave deeper into the maze. Our crampons bit firmly into the glassy ice, with their clean, razor-sharp the teeth. It felt reliable. because the ice steepened, and we started to climb additional into the frozen labyrinth, the ropes all started. the times of labor through the Sherpas confirmed us the course, because the ropes snaked away into the space. We clipped our karabiners that have been hooked up to our harnesses directly to the fastened line. The rope tangled up and over the partitions of ice in entrance folks. a number of powerful pushes and we might clamber over their lip, mendacity there respiring seriously within the ever greater air. There forward may then be the subsequent contorted ice face that previously were hidden. As we went greater we started to see Base Camp under us, getting smaller within the distance. i used to be being used to donning crampons back and stepped conscientiously to prevent tearing my windsuit at the sharp tooth. i used to be rusty, and two times the blades sliced a gash within the fabric as i attempted to kick a crampon into the ice. The sunrise introduced with it a few haze and shortly Base Camp used to be obscured from sight. We checked our gear back, and saved relocating on. The speed in the back of the Sherpas used to be regular and possible; i used to be feeling solid. regardless of now going larger than I have been due to the fact that we had arrived in Nepal, i used to be coping ok within the thinner air. quickly we got here to the 1st of the aluminium ladders that spanned the yawning chasms that seemed among the damaged ice. complex platforms of ropes secured those ladder bridges, yet nonetheless sometimes we'd achieve some extent the place the crevasse had shifted. the following the present ladders will be suspended, twisted within the air, ropes torn aside because the weight of the relocating ice wrenched the buildings asunder. we'd wait and watch as Nima and Pasang, who have been often referred to as the Icefall ‘doctors’, may get to paintings repairing and solving the direction throughout. All paintings within the Icefall was once undertaken in silence. It used to be most secure like this. in the course of the general breaks that we'd take, the Icefall medical professionals could quietly smoke, leaning opposed to the ice partitions throughout.

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WMUR.com Outdoors Editor Paula Tracy spoke Wednesday night to Sports Director Jamie Staton on News 9 about the new page aimed at motivating people to get outdoors.
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8 February 2016
By Parag Khanna
From China to Africa to Mexico, the entire world is on the move. A record nine million Americans live abroad, but the US is still a top destination for migrants. Migration across developing countries shows the fastest growth, with workers crisscrossing Africa, the Middle East and Asia.
See more maps from Connectography and order the book here.

domain: geography


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Just sitting here basking in the joy of an open heart and a clear mind after an excellent session of therapy.
Celebrating the high with the almost-rain backdrop, chai and the closest-to-Parisian croissant I’ve found in Bangalore.
increasingly, therapy has become a very quiet affair, for me. Far fewer words, working mostly with my body, movement and dreams (when I remember them), lots of quiet and noticing what happens in those quiet moments, really taking the time to soak that in before ticking off items from the mental list to move on to the next thing.
It has brought about a sense of expansiveness not just in the way that therapy is working to open me up, but also in the way that I am experiencing life itself. Open, quiet, slow and free.
Today was an important session. And I spent much of it in a haze of peace and oneness. Not having the words or even the urge to explain what I was feeling. It’s such a relief to have a therapist who works in this way, with whom I can spend the entire hour in mostly silence, without owing explanations and still feel held, safe and grounded. Today has left me feeling very present in the now. In today. In what my body is experiencing as this sense of peace and togetherness.
We always end with “so how are you feeling now?” and usually my answer is the woefully inadequate “good” or “not so good” (as the case may be). Today I burst into a beaming, heartful smile and said, Blissful.


Pairing Around (A Prelude for Two Trumpets and Two Bassoons)
Pairing Around (A Prelude for Two Trumpets and Two Bassoons) was composed in 1987 in Winston-Salem, North Carolina for the Ensemble Josquin Des Pres in France. The opening of the piece is a four-part round and it is desirable that this section be performed in procession. Before beginning the composition the four performers should be located in the rear of the concert hall. At each instrument’s entrance, the player begins processing to the stage (one step per bar). After all four instruments have entered into the round, the number of repetitions of it will vary according to the size of the processional space and such adjustments are left up to the ensemble’s discretion. Shortly after the ensemble arrives on stage, the round should begin to end with instruments exiting in the reverse order in which they first appeared (with or without full repetition of the round). Once on stage, it is suggested that the players be widely spaced apart so as to fill the entire performance space.
The performance format is as follows:
1.Bassoon 1 – begins the round, continually plays the complete round
2.Trumpet 1 – begins the round when Bassoon 1 reaches bar #5; continually plays the complete round
3.Bassoon 2 – begins the round when Trumpet 1 reaches bar #5; continually plays the complete round
4.Trumpet 2 – begins round when Bassoon 2 reaches bar #5; continually plays the complete round.
The round continues until all are on stage. Once on stage:
1.Bassoon 1 – first to stop playing upon reaching bar #16
2.Trumpet 1 – second to stop playing upon reaching bar #16
3.Bassoon 2 – third to stop playing upon reaching bar #16
4.Trumpet 2 – takes the Last Ending, attacca, to the next section
If a procession through the concert hall is not possible or practical, the players may enter in procession (as described above) from the wings of the stage. In rare circumstances the procession may even be eliminated, with the round played in concert seating, but this is not encouraged. Due to the processional, it is highly recommended that this piece be used to either open the first or second half of a concert.
Each repetition of the round = ca. 20”
Remainder of movement = ca. 3’
Approximate total duration of the composition = 6’
Winston-Salem, North Carolina


- Published: Wednesday, 04 October 2017 08:47
- Written by Abigail Malalis
- Hits: 1200
Gone are the days when people living in the hinterland barangays of Cagayan de Oro experienced economic hardship due to terrible road condition thus preventing them to deliver their farm products to the city.
Under the administration of Mayor Oscar Moreno, there is no stopping in road concreting projects, giving easy access to transportation of goods and adding vibrant to economic activities in the hinterland barangays.
"GIKAN SA KATAWHAN, IBALIK SA KATAWHAN"
Photos by Jomar Figuracion/CIO


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The paper analyzes rights-based and economic approaches to the provision of health care and education in developing countries. It assesses the foundations and uses of social rights in development, outlines the economic approach to health care and education, highlights differences and similarities, and assesses the hard questions that the economic critique poses for rights. The paper argues that the policy consequences of the approaches overlap considerably. Differences include the consequences of long-term deprivation, metrics for tradeoffs, and the behavioral distortions of subsidies. But the differences are not irreconcilable, and advocates of the approaches need not regard each other as antagonists.
All Science Journal Classification (ASJC) codes
- Geography, Planning and Development
- Sociology and Political Science
- Economics and Econometrics
- Health care
- Human rights
- Social rights