Self-correction

As a project progresses and you monitor performance, there will be times when actual does not measure up to plan. This calls for corrective action. However, don t be too quick to take action. Some deficiencies turn out to be self-correcting. It is unrealistic to expect steady and consistent progress day after day. Sometimes you ll fall behind and sometimes you ll be ahead, but in a well-planned project, you will probably finish on schedule and within budget. 

A method of successive approximation (s.a. method) is one that would provide the solution as the limit of an infinite sequence of steps if these steps were carried out exactly. These steps are usually quite simple, and nearly identical, each to the next, so that programming is a relatively easy task. Most methods operate upon a given approximation to obtain a better one, hence they are self-correcting. Because of rounding, at some stage the computed correction will no longer be... 

The method is, of course, not self-correcting, and errors can accumulate. However, the local methods require initial approximations, and the approximations provided by this method may be improved if necessary, by applying a local method. 

Quality systems are intended to be self-correcting and self-improving. Triggers that prompt corrective or preventive actions can come from a number of sources. 

Where possible plants of intrinsically safe design are preferred, i.e. those which have been designed to be self-correcting rather than those where equipment has been added on to control hazards. Some characteristics of intrinsically safe plants are ... 

Of course, this self-correction error is not limited to one electron systems, where it can be identified most easily, but applies to all systems. Perdew and Zunger, 1981, suggested a self-interaction corrected (SIC) form of approximate functionals in which they explicitly enforced equation (6-34) by substracting out the unphysical self-interaction terms. Without going into any detail, we just note that the resulting one-electron equations for the SIC orbitals are problematic. Unlike the regular Kohn-Sham scheme, the SIC-KS equations do not share the same potential for all orbitals. Rather, the potential is orbital dependent which introduces a lot of practical complications. As a consequence, there are hardly any implementations of the Perdew-Zunger scheme for self-interaction correction. 

Several isospecific Ci-symmetry catalysts have also been described including (12-15). When activated with [Ph3C]+ [B(C6F5)4]-, (12) affords highly regioregular i-PP (mmmm = 95%) with the stereochemical defects predominantly being isolated rr triads, consistent with a self-correcting enantiomorphic site-control pathway. 2,73 The isospecificity was therefore explained by a mechanism... 

An automatic controller is an error-sensitive, self-correcting device. It takes a signal from the process and feeds it back into the process. Therefore, closed-loop control is referred to as feedback control. 

Entities resulting from self-assembly and self-organization of a number of components may undergo self-correction and adaptation. This might also explain why large multisite protein architectures are formed by the association of several smaller protein subunits rather than from a single long polypeptide. 

At present, most of Shell s robots are self-correcting in that they can be programmed to respond to particular kinds of error. Newer robots will be more involved in making on-line decisions, and could ultimately evolve into expert systems. 

Second, by actually monitoring the state of the material, it is possible to control the fabrication process by data rather than a procedure, such as a set time temperature sequence. This means one can have a self-correcting, automated, intelligent cure process that can adapt to variations in material age, fabric permeability, tool heat transfer characteristics, and the like. 

The above discussion is based on the reversible reactions that produce the most thermodynamically stable products. In contrast, irreversible reactions produce kinetically-controlled products. In such cases, the self-correction mechanism is not operative. Well-defined building blocks with appropriate geometrical features are even more important for the synthesis of kinetically-controlled macrocycles. It is possible to obtain larger cycles because different sizes of linear species form in the reaction, which will cyclize to give a mixture ofdifferent sizes of cycles. Smaller cycles will still be favored over larger cycles in such kinetically-controlled reactions owing to kinetic factors. 

As tho temperature iB maintained constant during the entire experiment, no correction on that score has to ho made the atmospheric pressure being altogether excluded from, exerting any influence upon the volumes or pressures, no haromctrical observations are requisite, and, as tho tension of aqueous vapor in f is exactly balanced by that in p, the instrument is, in this respect, self-correcting,... 

It is often found that, where reasonably generous control limits are agreed, the rises and falls in inhibitor reserve will be self-correcting and not require a slavish attitude to dosing pump adjustment. Nevertheless, the program minimum inhibitor reserve should still be sufficient to always provide adequate system protection, so a hands-off approach to pump adjustments will inevitably result in somewhat higher costs than are possible. 

Hite, M., Federici, C., Turner, S., and Fassihi, R. Novel design of a self-correcting monolithic controlled-release delivery system for tramadol. Drug Del. Tech. 3 48-55, 2003. 

Irreversible self-assembly involves the formation of a product through a series of irreversible (usually covalent) bond-forming steps under kinetic control. There is no margin for self-correction and any mistakes are fatal to the formation of the final assembly. This class of reaction is not of significant interest in supramolecular chemistry but is topical in organic synthesis as tandem or domino reactions.2... 

Several kinds of failures may compromise safety and productivity of industrial processes. Indeed, faults may affect the efficiency of the process (e.g., lower product quality) or, in the worst scenarios, could lead to fatal accidents (e.g., temperature runaway) with injuries to personnel, environmental pollution, and equipments damage. In the chemical process fault diagnosis area, the term fault is generally defined as a departure from an acceptable range of an observed variable or a parameter. Fault diagnosis (FD) consists of three main tasks fault detection, i.e., the detection of the occurrence of a fault, fault isolation, i.e., the determination of the type and/or the location of the fault, and fault identification, i.e., the determination of the fault profile. After a fault has been detected, controller reconfiguration for the self-correction of the fault effects (fault accommodation) can be achieved in some cases. 

Once a fault has been detected, in some applications a controller reconfiguration for the self-correction of the fault is required (fault accommodation). A fault-tolerant control system possesses this capability, and its adoption is of the utmost... 

Even better, a well-designed PAT system has built in the capability of self-correcting many kinds of problems. This cybernetic capability—much like the thermostat on a home heating system—senses the appropriate press pressure level and self-corrects if it exceeds norms. The cybernetic capability is more certain and more rapid than the notification of a human to take corrective actions. 

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