Speed of response

Chemical gas sensors are characterized by properties such as sensitivity and selectivity, which has been discussed in Section 2.2. Properties like speed of response and long-term stability are of crucial importance for applications such as combustion control in car exhausts or flue gases from boilers. 

The speed of response is normally determined by the adsorption, desorption, and chemical reactions of the gas molecules on the sensor surface. The time constants 

when the gas surface reactions can be expected to occur at a faster rate. Now it is seen that the response has reached a steady-state value after exposure to the ammonia atmosphere. The extra dip in the response curve seen in the oxygen environment might be due to the slow diffusion of ammonia. Some gas molecules might still be left under the sensor surface in this experiment when hit by the oxygen gas outlet. 

Due to the results mentioned in Section 2.4.1 by Tobias et al. [110] and Gosh [6] et ah, the authors tested the response (not using the MGO equipment) of the MISiG-FET sensors at 500°G for different constant current levels. A current of 65 juA showed the same fast speed of response as for normal operation at 100 juA. For a constant current of 500 /t A, the MISiG-FET showed the same size and speed of response but also a slow drift of the baseline, which was not sensitive to a change between oxygen and hydrogen. 

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Various accessories can be suppHed along with the control valves for special situations. Positioners ensure that the valve stem is accurately positioned following small or slowly changing control signals or where unbalanced valve forces exist. Boosters, which are actually pneumatic amplifiers, can increase the speed of response or provide adequate force in high pressure appHcations. Limit switches are sometimes included to provide remote verification that the valve stem has actually moved to a particular position. 

Proportional-plus-Integral-plus-Derivative (PID) Control The derivative mode moves the controller output as a function of the rate-of-change of the controlled variable, which adds phase lead to the controller, increasing its speed of response. It is normally combined... 

Peiformance. Depending on the application, accuracy, repeatability, or perhaps some other measure of performance is appropriate. Where closed loop control is contemplated, speed of response must be included. 

Optical UV scanners or flame rods should be used because of the speed of response. 

It should be emphasized at this point that the speed of response is cnti-cal. The pressure transient pressure should not fall to less than 50% of the difference in pressure between the standby pump start pressure and the low oil pressure trip pressure. This is normally achievable with good design practice and the use of a switch and direct wiring. There is some tendency to use a transmitter and control through a remote computer. The latter arrangement is difficult to check on a shop test and normally is too slow to meet the requirement. An accumulator can be added and must be used if the requirement cannot be met. This additional hardware contributes to higher initial cost and possible reliability problems in the future. The direct switch method is therefore highly recommended. 

The best anti-surge control is the simplest and most basic that will do the job. The most obvious parameter is minimum-flow measurement, or if there is a relatively steep pressure-flow characteristic, the differentia pressure may be used. The latter parameter allows for a much faster response system, as flow measurement response is generally slow however, the speed of response need only be fast enough to accept expected transients. One major problem with the conventional methods of measurement and control is the need to move the set point for initiation of the control signal away from the exact surge point to allow some safety factor for control response time and other parameters not directly included... 

Finally, the speed of response of the detector sensor and the associated electronics once played an important part in optimum column design. The speed of response, or the overall time constant of the detector and associated electronics, would be particularly important in the analysis of simple mixtures where the analysis time can be extremely short and the elution of each peak extremely rapid. Fortunately, modern LC detector sensors have a very fast response and the associated electronic circuits very small time constants and, thus, the overall time constant of the detector system does not significantly influence column design in contemporary instruments. The instrument constraints are summarized in Table 2... 

To conclude, this sampling of the literature of risk perception, the comments of Covello, 1981 may be summarized. Surveys have been of small specialized groups - generally not representative of the population as a whole. There has been little attempt to analyze the effects of ethnicity, religion, sex, region age, occupation and other variables that may affect risk perception. People respond to surveys with the first thing that comes to mind and tend to stick to this answer. They provide an answer to any question asked even when they have no opinion, do not understand the question or have inconsistent beliefs. Surveys are influenced by the order of questions, speed of response, whether a verbal or numerical respon.se is required and by how the answer is posed. Few Studies have examined the relationships between perceptions of technological hazards and behavior which seems to be influenced by several factors such as positive identification with a leader, efficacy of social and action, physical proximity to arenas of social conflict. 

Type of thermometer Temperature range ( C) Accuracy Speed of response... 

Mechanical switches provide a simple manual interface to operate all sorts of loads, but they suffer from all the drawbacks of manual control, namely in terms of speed of response, and also requiring permanent operator awareness. 

Engine speed is controlled by the use of variable-speed governors that can be mechanical, mechanical-hydraulic or electronic. The last option is gaining wide acceptance for generation purposes due to its speed of response and ready integration with other control equipment used in fully automated installations (probably incorporating more than one generating unit). 

It must be sensitive to the desired wavelength of light, which in current manufacturing practice is 436 nm. Sensitivity must also be apparent in the speed of response shown to irradiation, since the reactions in the polymer must be complete within milliseconds. 

A final comment on the Czochralski Method GaAs has become important in construction of integrated circuits for computers because of the promise of speed of response and density of components, compared to silicon wafers. Both As and Ga tend to oxidize in air as they approach the melt stage and AS2O3 sublimes. Both elements are toxic to man. In the... 

With respect to pH sensitivity and an adequate speed of response (time constant r = RC where R is the resistance of the measuring circuit and C the capacitance of the electrode), a certain degree of superficial swelling is needed however, the gel layer thus formed should remain thin in order to minimize the solubility of the glass and to guarantee sufficient durability of the electrode. In this respect lithium barium silicates offer an attractive compromise32. 

PI controllers are most common. They eliminate offsets and have acceptable speeds of response in most industrial settings. We usually pick a low to intermediate gain (wide proportional band, PB 150) to reduce the effect of noisy signals (from flow turbulence also why we do not use D control). We also use a low reset time ( 0.1 min/repeat i.e. relatively large I action) to get fast set-point tracking. 

The present paper applies state variable techniques of modern control theory to the process. The introduction of a dynamic transfer function to manipulate flow rate removes much of the transient fluctuations in the production rate. Furthermore, state variable feedback with pole placement improves the speed of response by about six times. 

Figure 7 shows some of the best results from these pole placement tests. The major difference between these curves and those of Figure 4 is the speed of response. The transient time has been reduced from 6 hours to about 1 hour. 

A control algorithm has been derived that has improved the dynamic decoupling of the two outputs MW and S while maintaining a minimum "cost of operation" at the steady state. This algorithm combines precompensation on the flow rate to the reactor with state variable feedback to improve the overall speed of response. Although based on the linearized model, the algorithm has been demonstrated to work well for the nonlinear reactor model. 

Their distinguishing feature is the high speed of response. This response develops on the scale of fluorescence lifetime of photophysical or photochemical events that provide the response and can be as short as 10 x-10 10 s. Because of that, the fluorescence reporting is never time-limiting, so that this limit comes from other factors, such as the rate of target - sensor mutual diffusion and the establishment of dynamic equilibrium between bound and unbound target. 

Remember that the NEP is defined as the incident signal power required to obtain a signal equal to the noise in 1 Hz bandwidth. Note that NEP is a measure of the S/N ratio, not just noise. The NEP and r both depend on the thermal conductance G, and sensitivity and speed of response can be traded off by varying G, with the constant NEP, the value of (r)1/2 being a useful figure of merit. 

The speed of response of the detector must be much faster than the rate of the CL reaction, if the signal output is not to be a distorted version of the true signal. 

Bai, J., Tucker, W. C. and Chapman, E. R. PIP2 increases the speed of response of synaptotagmin and steers its membrane-penetration activity toward the plasma membrane. Nat. Struct. Mol. Biol. 11 36-44,2004. 

Locate the detectors as close as possible to the anticipated source of fire or explosion to increase signal strength and speed of response. 

Careful attention must also be paid to ensuring that no air bubbles are in the water piping, that the fastest possible water valves are utilized, and that the water nozzles are also as close as possible to the potential hazard to minimize the travel time of the water. These considerations will improve speed of response of the fire detection system to a much greater degree than improving the speed of the detector alone. 

The correct understanding of these words and their implications is of fundamental importance for the scientific and industrial community interested in sensor science development, since it allows the correct dissemination of both experimental and theoretic results, even if other important terms in the sensor field have not been discussed in this chapter, such as speed of response, reversibility, repeatability, reproducibility, and stability, to which some attention was paid during the presentation of this work at the ASI. 

For the case of the bias estimation, several runs were performed simulating a known bias in one of the measurements, assuming different initial values of the variance of the bias. From Fig. 4 it can be seen that the convergence and the speed of response are heavily dependent on the initial values of. To help in the interpretation... 

Reaction Time. There are many different tests used to measure reaction time. These tests measure the period of time between the presentation of a stimulus to a patient and the onset of the resulting response. The signal is usually a visual or auditory stimulus, and the onset of a motor reaction, such as the lifting of a finger, arm, or leg or the pressing of a buzzer, is used to measure the speed of response. 

The speed of response of the photodiode depends on the diffusion of carriers, the capacitance of the depletion layer, and the thickness of the depletion layer. The forward bias itself increases the width of the depletion layer thus reducing the capacitance. Nevertheless, some design compromises are always required between quantum efficiency and speed of response. The quantum efficiency of a photodiode is determined largely by the absorption coefficient of the absorbing semiconductor layer. Ideally all absorption should occur in the depletion region. This can be achieved by increasing the thickness of the depletion layer, but then the response time increases accordingly. 

Rise time (speed of response) the time it lakes the process to come up to the new setpoint... 

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