Process response

In testing process systems, standard input disturbances, such as the unit-step change, unit pulse, unit impulse, unit ramp, sinusoidal, and various randomised signals, can be employed. 

All the above changes are easily implementable in dynamic simulations, using MADONNA and other digital simulation languages. The forms of response obtained differ in form, depending upon the system characteristics and can be demonstrated in the various MADONNA simulation examples. The response characteristics of real systems are, however, more complex. In order to be able to explain such phenomena, it is necessary to first examine the responses of simple systems, using the concept of the simple, step-change disturbance. 

---

Kubo R, Yokota M and Nakajima S 1957 Statistical-mechanical theory of irreversible processes. Response to thermal disturbance J. Phys. Soc. Japan 12 1203... 

This is essentially the same process responsible for deactivation of photoexcited cyanine dyes. 

A key feature of MFC is that future process behavior is predicted using a dynamic model and available measurements. The controller outputs are calculated so as to minimize the difference between the predicted process response and the desired response. At each sampling instant, the control calculations are repeated and the predictions updated based on current measurements. In typical industrial applications, the set point and target values for the MFC calculations are updated using on-hne optimization based on a steady-state model of the process. Constraints on the controlled and manipulated variables can be routinely included in both the MFC and optimization calculations. The extensive MFC literature includes survey articles (Garcia, Frett, and Morari, Automatica, 25, 335, 1989 Richalet, Automatica, 29, 1251, 1993) and books (Frett and Garcia, Fundamental Process Control, Butterworths, Stoneham, Massachusetts, 1988 Soeterboek, Predictive Control—A Unified Approach, Frentice Hall, Englewood Cliffs, New Jersey, 1991). 

The process responsible for initiating RES follows from the earlier discussion of radiation damage in graphite. Specifically, in a displacement event a Frenkel pair... 

An event tree is a model of the process response to an accident initiator. The initiators are... 

In investigations of the failure of fiber compositions (PETP — short glass fibers) [251] it was found that the main process responsible for composite failure under load is the rupture at the matrix-fiber interface. The author of [251] observed formation of microvoids in loaded samples, both at the interphases and in the bulk. The microvoids, or cavities) grow in size and become interconnected by microcracks, and this results in fiber separation from the binder. However, when the matrix-fiber bond is strong enough, the cavities appear mostly in the bulk of matrix, the failure of the specimen does not over-power cohesion and traces of polymer remain on the fibers. 

In an effort to determine the processes responsible for this type of behavior, Akiba and Tanno (A3), Sehgal and Strand (S2), and Beckstead (B6) have studied the coupling between the dynamics of the combustion process and the dynamic ballistics of the combustion chamber as described by Eq. (7). Each of these investigators has postulated admittedly simplified but slightly different combustion models to couple with the transient ballistic equations. Each has examined the combined equations for regions of instability. The results of these studies suggest a correlation between the L of the motor (the ratio of combustion-chamber volume to nozzle throat area) and the frequency of the oscillations. 

The problem with the Arrhenius definitions is that they are specific to one particular solvent, water. When chemists studied nonaqueous solvents, such as liquid ammonia, they found that a number of substances showed the same pattern of acid-base behavior, but plainly the Arrhenius definitions could not be used. A major advance in our understanding of what it means to be an acid or a base came in 1923, when two chemists working independently, Thomas Lowry in England and Johannes Bronsted in Denmark, came up with the same idea. Their insight was to realize that the key process responsible for the properties of acids and bases was the transfer of a proton (a hydrogen ion) from one substance to another. The Bronsted-Lowry definition of acids and bases is as follows ... 

The redox processes responsible for the switching of the bridging redox polymer can also be brought about by redox processes induced by molecular species in solution Alternatively, the switching processes can be designed so that a solution component is essential for, or mediates the redox process. The array electrode can then be used as a sensor for those solution constituents. 

So far we have not gone in-depth into the nature of the transport processes responsible for fluxes of material between and within reservoirs. This section includes a very brief discussion of some of the processes that are important in the context of global biogeochemical cycles. More comprehensive treatments can be found in textbooks on geology, oceanography and meteorology and in reviews such as Lerman (1979) and Liss and Slinn (1983). 

The shape of the so called master curve, however, depends strongly on the compound formulation and the type of contact surface in the friction process. Its detailed study gives an insight into the processes responsible for the frictional behavior. 

TNF. Tumor necrosis factor. TNFs are among the important cytokines playing a key role in activation and induction of some immune system cells and cellular immunity processes responsible for proinflammatory and inflammatory response reactions as well. 

Fig. 2.5 illustrates the effect on the process response of increasing values of k. This shows that the response time of the system is decreased by increasing values of k and that the final effluent concentration leaving the tank is reduced in magnitude. Increasing k has, however, very little influence on the initial rate of response. 

Many process response curves have an S-shaped form, as given in Fig. 2.19. 

Table 2.2. Controller settings based on process responses. ...

Acid-base disturbances are always manifestations of underlying clinical disorders. It is useful to specifically define the primary acid-base abnormality, as each disorder is caused by a limited number of disease processes. Establishing the specific disease process responsible for the observed acid-base disorder is clinically important because treatment of a given acid-base disorder will only be accomplished by correcting the underlying disease process. 

It is quite possible that phenolic acids may produce more than one effect on the cellular processes responsible for mineral absorption. The potential sites of action discussed above all involve cellular membranes in some way. Which mechanism of action is predominant in a given situation may depend upon the concentration of allelochemicals present and the conditions (e.g. pH) of the plant/chemical interaction. 

---