Constraints in design

The central constraint in designing for on-line operation was the maintenance of the integrity of the method chemistry. To be commercially attractive, the system would also have to be as reliably free of maintenance as possible, including calibration, so reagent stability and/or purification would need to be addressed. 

Because the unit row eigenvector is not a linear function of the mask, the quasi-interpolation degree is not necessarily a linear constraint in design space. 

The difficulty in identifying and enforcing safety constraints in design and operations has increased from the past. In many of our older and less automated systems, physical and operational constraints were often imposed by the hmitations of technology and of the operational environments. Physical laws and the Umits of our materials imposed natural constraints on the complexity of physical designs and allowed the use of passive controls. 

The constraints in designing tubular and convective reformers are hence primarily the mechanical material properties. The catalyst volume may then be considered a derived property. However, high catalyst activity is essential to ensure low tube-wall temperature. A higher... 

One of the constraints in designs of calcium anode-based thermal batteries has been the limited duration at high current densities due to a low electrochemical efficiency of the calcium anode, arising from the existence of side-reactions involving the electrolyte and the electrode active materials. It has been demonstrated by Mine Safety Appliances Ltd that significant improvements in thermal battery performance can be achieved by the use of lithium as the active anode material in the cell, coupled witn new cathodes. These batteries... 

Expert systems are widely applied in design and planning where they can give instructions on how to design systems for given criteria or constraints. Expert systems are also used for simulation tasks Starting from an initial state, these systems deduce subsequent states with the aim of simulating possible outcomes for certain actions. 

Sometimes a compromise in the quality of the inputs (perhaps due to non-availability of a particular component to the required specification) may be necessory to avoid a production delay. Similar constraints in the design or process may also make it necessary to have a deviation in design, without undermining the quality requirements. The ISO emphasizes that, for such deviations, written authorization from a competent authority, and preferably also the written consent of the customer, is essential before implementing sueh a change. This will be for a specific period and for a specific number of items. 

The first concern in designing process capable products is to guarantee the proper functioning of the product, and therefore to satisfy technical constraints. Dimensional... 

The first step in designing a stack for air pollution control purposes is to determine exactly what regulatory constraints and requirements exist at the particular site. These constraints and requirements may be so severe that alternative means of air pollution control may have to be sought. In any case, the regulations specify a performance standard to which the stack must be designed, and against which the design can be evaluated. 

If the measured material properties satisfy the constraints in this section, then we can proceed with confidence to design structures with the material. Otherwise, we have reason to doubt either the material model or the experimental data or bothi... 

It is a common problem that one wishes to constrain an object from moving in some direction while allowing it to move in other directions. Many mechanisms have been designed and built that allow quite stiff constraints in one direction while allowing unlimited motion in another. Typically these mecha-... 

When the range of travel is hmited, it is sometimes practical to design mechanisms that rely on elastic deformation of an element to allow the motion, while providing robust constraint in other directions. Such mechanisms are often called flexures. When hghtly loaded these can have infinite lifetimes and no maintenance. There are a large range of such devices that have been designed and used for various applications. 

As a result, a considerable amount of effort has been expended in designing various methods for providing difference approximations of differential equations. The simplest and, in a certain sense, natural method is connected with selecting a, suitable pattern and imposing on this pattern a difference equation with undetermined coefficients which may depend on nodal points and step. Requirements of solvability and approximation of a certain order cause some limitations on a proper choice of coefficients. However, those constraints are rather mild and we get an infinite set (for instance, a multi-parameter family) of schemes. There is some consensus of opinion that this is acceptable if we wish to get more and more properties of schemes such as homogeneity, conservatism, etc., leaving us with narrower classes of admissible schemes. 

Hudlicky, T. (1996) Design Constraints in Practical Syntheses of Complex Molecules Current Status, Case Studies With Carbohydrates and Alkaloids, and Future Perspectives. Chemical Reviews, 96, 3-30. 

Criteria and constraints in production planning, scheduling, and design of batch plants... 

The nature of the relationships and constraints in most design problems is such that the use of analytical methods is not feasible. In these circumstances search methods, that require only that the objective function can be computed from arbitrary values of the independent variables, are used. For single variable problems, where the objective function is unimodal, the simplest approach is to calculate the value of the objective function at uniformly spaced values of the variable until a maximum (or minimum) value is obtained. Though this method is not the most efficient, it will not require excessive computing time for simple problems. Several more efficient search techniques have been developed, such as the method of the golden section see Boas (1963b) and Edgar and Himmelblau (2001). 

If we have a second order system, we can derive an analytical relation for the controller. If we have a proportional controller with a second order process as in Example 5.2, the solution is unique. However, if we have, for example, a PI controller (2 parameters) and a first order process, there are no unique answers since we only have one design equation. We must specify one more design constraint in order to have a well-posed problem. 

Every modification in design, as well as remedial actions, must be made after due consideration of building physics. Otherwise negative side effects can occur. Examples are locally high relative humidity in air, condensation of moisture and development of mold. With due consideration to the constraints laid by building physics, however, modifications to radon safe design can give positive tradeoffs as reduced possibility for moisture transport and development of mold. 

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