Sensitivity to disturbances

Advantages include low concentration in the ventilated zone can be achieved and relatively high contaminant removal and temperature effectiveness. However, the srratificacion strategy is sensitive to disturbances and stagnant areas with high... 

Certain types of fuxes become extremely sensitive to disturbance after exposure to wet soil Detonation in place is the only safe method of neutralizing or removing such deteriorated boobytraps. 

In these tests NMe showed the detonation-to-shock and shock-to-detonation transition characteristic of a homogeneous expl even with barriers as thin as 25fi- The reaction zone had a peak of probably less than 1 Ofi thickness. Nonporous 60/40-RDX/TNT was less sensitive to disturbance by thin barriers than NMe. A 250/r thick barrier could cause a disturbance in the reaction, but there was no delay and very little overshoot of the type usually associated with homogeneous expls. Experimental arrangements shown in Figs 1, 2, 3, 4 and 6 are not reproduced here... 

Prior to 1940, the applications of IR spectroscopy were limited to research in molecular structure using spectrometers built by research workers. These spectrometers were difficult and tedious to use the spectrum had to be measured and plotted point by point, and the spectrometers were extremely sensitive to disturbances such as small fluctuations in room temperature. Interest in the military applications of IR radiation led to the development of improved IR detectors during World War II this made possible the construction of commercial automatic-recording IR spectrometers. The resulting simplicity and rapidity of operation made IR spectroscopy a standard tool in research and industrial work. 

These results illustrate an inherent disadvantage of this system. The first reactor is the most sensitive to disturbances. The changes in its exit temperature will be greater than those of the other downstream reactors. 

An initial theoretical study (Gilliland et al. 1964) established that, for a simple plant model consisting of a continuous stirred-tank reactor (CSTR) and a distillation column, the material recycle stream increases the sensitivity to disturbances together with increasing the time constant of the overall plant over those of the individual units. Moreover, it was shown that in certain cases the plant can become unstable even if the reactor itself is stable. 

Luyben (1993a) provided valuable insights into the characteristics of recycle systems and their design, control, and economics, and illustrated the challenges caused by the feedback interactions in such systems, within a multi-loop linear control framework. Also, in the context of steady-state operation, it was shown (Luyben 1994) that the steady-state recycle flow rate is very sensitive to disturbances in feed flow rate and feed composition and that, when certain control configurations are used, the recycle flow rate increases considerably facing feed flow rate disturbances. This behavior was termed the snowball effect. ... 

In the second simulation (Figure 7.12b), the reactor-inlet flow was increased from 74000 kg/h to 81500kg/h. Initially, the amounts of VCM produced and of fresh EDC fed increase. However, these flows soon decrease to the initial values. This means that, when reaction conditions are fixed, production-rate changes can be achieved only at the expense of large variations of the recycle flow. Moreover, all the flow rates are very sensitive to disturbances if a control structure fixing the flow rate at the plant inlet is used. 

The problem of the stability of the two modes of steady-state propagation of the temperature wave over the reaction sample needs a separate study. From qualitative considerations it follows that the faster process is less sensitive to disturbances (both mechanical and thermal) than the slower one. It is evident that in the case of slow motion any kind of inhomogeneities in the sample [e.g., a local reduction in the strength, leading to a decrease in (dT/dx) 1 may cause a displacement of the reaction-onset coordinate to the fore part of the front and thereby induce a spontaneous transformation of the slower wave into the faster one. 

We can observe their behavior directly or check later for any changes at the scent mounds made by the beavers. The first can be difficult because the animals are very sensitive to disturbances such as the presence of humans especially in groups. 

Since there is no radial flow, the reactor will be very close to adiabatic, even with small reactor diameters. There are also limited possibilities to introduce a heat exchanger between the monolith beds. The two-phase flow is sensitive to disturbances. However, in the existing plants temperature control is no problem, due to the high heat capacity of the liquid and the low conversion in each passage. An external heat exchanger in the liquid flow is sufficient to control the reactor temperature. 

Compared to the physical/chemical test systems, the characterisation of biological test systems is quite another kettle of fish (literally ). Such test systems have not only to be described by a few specifications provided by the manufacturer , but they have to be cared for, properly housed or sited, they may need acclimatisation to the test environment before use, and their characteristics may need to be re-ascertained on a regular basis. They may react very sensitively to disturbances in their environment, and therefore the quality of the data obtained from these test systems can be ensured only through the establishment of the proper conditions. Consequently, the list of points to be observed with biological test systems for ensuring their GLP-compliance is more extensive than the one for the physical/chemical systems. 

Metal detectors have been in use since World War II and are still the most effective sensors for use against landmines and other UXO. There are two types of metal detectors. One detects anomalies in the earth s magnetic field caused by ferrous (iron-based) materials. The other creates an electromagnetic field that can detect both ferrous and nonferrous metals. Improvements made to metal detectors have reportedly been in processing sensor information, weight reduction, and improved sensitivity to disturbances in the magnetic field caused by metallic objects. 

The described phenomenon is irreversible a decrease in the distance Z below Zcr does not apparently result in a change of the new state of the film. The following important property of the system should be emphasized when the distance Z is only slightly smaller than the critical distance, the system is very sensitive to disturbances. A very small increase of / (above the critical value) or a slight perturbation of the film (e.g. moving the system) are sufficient to initiate spontaneous change in the state of the film described above. 

The comparison of open and closed-loop responses (12.37) and (12.38) reveals that the sensitivity function S gives the reduction of sensitivity to disturbances, achieved by feedback control. It is evident that S =0 and T = 1 are desirable. In this way, the output follows perfectly the setpoint, and the process is not affected by disturbances. Both can be achieved by large controller gain, that is oo. However, large controller gain leads to instability, which sets limits on the achievable closed-loop performance. 

From steady state point of view, the size of equipment should be kept as small as possible in order to minimise the capital cost and prevent safety risks. However, a too small volume increases the sensitivity to disturbances, and in the worst case can upset the operation. Therefore, the design should provide sufficient capacity to dump fluctuations, although an excessive value would give too long transients. Hence, the design of capacities is a matter of optimisation, both from steady state and dynamic viewpoint. 

The maximum AT is about half AT/, and the reactor could be operated with a good margin of safety. The peak temperature and sensitivity to disturbances should be checked by numerical integration. 

The modem papermaking process is very sensitive to disturbances. The formation of deposits is one of the most important factors limiting the productivity on a paper machine today. Further, paper defects (such as breaks, holes and spots very often caused by deposits) represent one of the most common complaints of a user/buyer of paper. Still paper machine deposit control as a means to improve paper quality and productivity does not get appropriate attention. On the contrary, deposit control is often considered unnecessary in the ultimate papermaking process, which all papermakers strive to reach. Academic research, with few exceptions, ignores the subject. 

Temperature profiles after a stepwise increase of the heating rate are shown on the right side of Eig. 10.29. These profiles show distinct nonlinear wave characteristics as discussed in the previous section. Therefore the process is sensitive to disturbances and composition control is required. Again focus is on an inferential control scheme. Measured variables are the temperatures on trays 4 and 60, which are located within the upper and the lower ware front. Hence, they show good sensitivity to disturbances. Manipulated variables are the heating rate and the reflux ratio. Eor this process neither input nor output multiplicities occur. 

The instrument bus furnishes power to those instruments most sensitive to disturbance while the relay bus (also called the "control bus") furnishes power to the less sensitive components, such as relays and motors, which not only are less sensitive to disturbance but are themselves actual sources of disturbance. If one of the alternator supplies breaks down or otherwise becomes unavailable, the relay bus would be switched to purchased power. To permit operation with the "rougher" purchased power, the relay circuits include a 2-sec timer and a number of time delay relays so that reactor shutdown does not ensue unless the r.elay bus voltage is off for 2 sec or longer. 

In practice it is found that, due primarily to buoyancy effects, it is not practical to make the layer extremely stable - it is possible only to considerably improve the stability. Thus, the layer remains sensitive to disturbances. Background disturbances in the fluid can cause abrupt loss of stabilization. The resulting turbulent patch is usually swept downstream, off the body, and stability restored, but the abrupt appearance and disappearance of these patches causes correspondingly abrupt changes in the drag, having serious effects on other aspects of vehicle performance. Vehicles in the ocean, of course, are not operating in a perfectly quiet environment both natural and manmade disturbances abound. 

In the short time interval (5 years) since cryo-probes were commercialized they have become an indispensable accessory for NMR. Initially, they were available on 500 MHz instruments but now they have been installed on 700 and 800 MHz spectrometers. The more recent cryostats, thanks to ingenious design, are now less sensitive to disturbances such as changes in room temperature and helium evaporation rates. All of these factors will ensure considerable improvements in the performance of these ultrastabilized magnet systems. 

---