Software redundancy

Accuracy has been conventionally defined as the sum of absolute value of the systematic error and the standard deviation of the meter (MiUer, 1996). Since in the absence of hardware or software redundancy the systematic errors cannot be detected, this conventional definition is not practical. Bagajewicz, (2005) defined accuracy with... 

Critical interlock While identifying the hazards it is important to categorize critical interlocks (for new plants, data/experience from similar plants may be helpful) for which sufficient backup may have to be arranged as a safety measure. In many of these cases, in addition to software interlock, hardware interlocks are also provided. In some cases, even mechanical protection is provided. A critical trip interlock pertinent to a turbine is an example. For turbine overspeed, condenser vacuum, etc., in addition to electronic interlock (with sufficient hardware/software redundancy), mechanical interlocks are provided so that the equipment is saved. Choke and kill in offshore is also an example of this. Regulations To meet the requirement of a regulatory board or company standards, measures are taken to enhance overall safety. Incorporation of these safety measures does not always mean that risk is adequately reduced. These measures could make the system acceptable for use, and a local regulatory board may require additional precautions. An example will elaborate the situation. Many turbine manufacturers give low forward power relays or reverse power... 

Similar analyse should be done for BSC base stations controller. In practice BSC base stations have big hardware and software redundancy and their reliability is at least on the level of 99,999% (BSC base stations controller unavailability is at average 3 min per year). 

J. M. Adams and A. Taha, An Experiment in Software Redundancy with Diverse Methodologies, Proc. of the Twenty-Fifth Hawaii International Conf on Systems Sciences 1992. 

The authors suspect that this fact is not currently widely accepted within the automotive sector. In addition, commercial pressures may mean that some traditional aerospace techniques, such as software redundancy, may not be readily acceptable in automotive sectors. 

Validation effort Safety is assure by simplified hardware and software redundancy... 

Note that the constants must be defined equal to their numerical values (defined = is on the keyboard). These definitions must be above the integral you wish to solve. Mathcad operates top down. Mathcad produces the same value for the integral that we obtained from TableCurve. This calculation is redundant with the calculations already performed in this section to inboduce new software by solving a problem for which we already know the answer. 

Provide redundant software—(software diversity) with a plausibility control... 

Software can be poorly designed data format specifications are perhaps incompatible, intermediate results are inaccessible, all data are lost if an input error is committed, or results and data are not transferable to other programs. The division into tasks (modules, menu positions) might reflect not human but computer logic, and the sequence of entries the user is forced to follow might include unnecessary or redundant steps. 

To reduce intensity effects, the data were normalized by reducing the area under each spectrum to a value of 1 [42]. Principal component analysis (PCA) was applied to the normalized data. This method is well suited to optimize the description of the fluorescence data sets by extracting the most useful data and rejecting the redundant ones [43]. From a data set, PCA assesses principal components and their corresponding spectral pattern. The principal components are used to draw maps that describe the physical and chemical variations observed between the samples. Software for PCA has been written by D. Bertrand (INRA Nantes) and is described elsewhere [44]. 

The principle cost of creating an ES is not the hardware on which the system runs or the software that is used to create it, but the cost of employing a human expert to create the system. Not only are human experts expensive creatures, but they also may be understandably reluctant to spend time developing a computerized copy of themselves, knowing that, the more perfectly they manage to distil their expertise into a computer system, the greater the chance that they will make themselves redundant. 

In Section 1.5 we briefly discussed the relationships of equality and inequality constraints in the context of independent and dependent variables. Normally in design and control calculations, it is important to eliminate redundant information and equations before any calculations are performed. Modem multivariable optimization software, however, does not require that the user clearly identify independent, dependent, or superfluous variables, or active or redundant constraints. If the number of independent equations is larger than the number of decision variables, the software informs you that no solution exists because the problem is overspecified. Current codes have incorporated diagnostic tools that permit the user to include all possible variables and constraints in the original problem formulation so that you do not necessarily have to eliminate constraints and variables prior to using the software. Keep in mind, however, that the smaller the dimensionality of the problem introduced into the software, the less time it takes to solve the problem. 

You can see that the model for a realistic process can become extremely complex what is important to remember is that steps 1 and 3 in Table 1.1 provide an organized framework for identifying all of the variables and formulating the objective function, equality constraints, and inequality constraints. After this is done, you need not eliminate redundant variables or equations. The computer software can usually handle redundant relations (but not inconsistent ones). 

In addition to the basic control loops, all processes have instrumentation that (1) sounds alarms to alert the operator to any abnormal or unsafe condition, and (2) shuts down the process if unsafe conditions are detected or equipment fails. For example, if a compressor motor overloads and the electrical control system on the motor shuts down the motor, the rest of the process will usually have to be shut down immediately. This type of instrumentation is called an interlock. It either shuts a control valve completely or drives the control valve wide open. Other examples of conditions that can interlock a process down include failure of a feed or reflux pump, detection of high pressure or temperature in a vessel, and indication of high or low liquid level in a tank or column base. Interlocks are usually achieved by pressure, mechanical, or electrical switches. They can be included in the computer software in a computer control system, but they are usually hard-wired for reliability and redundancy. 

A traditional approach to fault diagnosis in the wider application context is based on hardware i.e. physical) redundancy methods which use multiple lines of sensors, actuators, computers and software to measure and/or control a particular variable. Typically, a voting scheme is applied to the hardware redundant system to decide if and when a fault has occurred and its likely location amongst redundant system components. The use of multiple redundancy in this way is common, for example with digital fly-by-wire flight control... 

The presented approach has been applied on the process illustrated in Figure 8. In this case, several physical redundancy relations are available but the same method can be successfully applied with a standard instrumentation fulfilled by software sensors [17]. r, T2, rs, re, rr and ril are based on physical redundancy, r4 and rs on functional redundancy, rg, rg and riO are derived from dynamical modeling. As expressed in Table 2, there is not one single residual that is representative of a specific fault. A diagnosticability analysis of the signature table shows that among the 256 different states of the system ... 

You can see from Fig. 9.8 that a Laue diffraction pattern is much more complex than a diffraction pattern from monochromatic X rays. But modern software can index Laue patterns and thus allow accurate measurement of many diffraction intensities from a single brief pulse of X rays through a still crystal. If the crystal has high symmetry and is oriented properly, a full data set can in theory be collected in a single brief X-ray exposure. In practice, this approach usually does not provide sufficiently accurate intensities because the data lack the redundancy necessary for high accuracy. Multiple exposures at multiple orientations are the rule. 

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