Design method

The design methods are normally a combination of one or more of the above methods. 

TABLE 9.9 Recommended Air Velocities to Ensure an Economic Minimum of Noise Production 

Velocity, m s , in Allowable sound pressure level, dB(A), in the room  

Apart from the energy constraints due to the friction losses, the main reason for limiting the air velocities in ducts is to reduce noise production. Some recommended air velocities are given in Table 9.9. 

7 Slope stability of fill and subsoil 8.4.3.7.1 Design methods 

All Ultimate Limit State (ULS) calculations are based on the assumption of a shd-ing mechanism and define the (overall) safety factor against failure as the ratio of the maximum available shear strength and the mobilised shear stress. 

Failure surfaces can have different shapes such as circular, logarithmic spiral, planar, combined, etc. Since different shapes can occur in nature, selecting a surface that is representative for the failure mode expected in the field is of utmost importance. This can be influenced by many aspects such as homogeneity of the soil, geometry of the slope, and loading conditions. 

The stability of slopes can be verified by means of two different approaches  

Both methods will briefly be discussed. For detailed discussion on these methods reference is made to specific literature or to the manuals of commonly used software such as the Geo-Slope, SLOPE/W manual (2012). 

---

Figure 16.5a shows the matches around the pinch from Fig. 16.4a with their duties maximized to tick-oflF streams. It should be emphasized that the tick-off heuristic is only a heuristic and can occasionally penalize the design. Methods will be developed later which allow such penalties to be identified as the design proceeds. 

This design procedure is known as the pinch design method and can be summarized in five steps... 

The philosophy in the pinch design method was to start the design where it was most constrained. If the design is pinched, the problem is most constrained at the pinch. If there is no pinch, where is the design most constrained Figure 16.9a shows a threshold problem that requires no hot utility, just cold utility. The most constrained part of this problem is the no-utility end. Tips is where temperature differences are smallest, and there may be constraints, as shown in Fig. 16.96, where the target temperatures on some of the cold... 

Figure 16.10 shows another threshold problem that requires only hot utility. This problem is different in characteristic from the one in Fig. 16.9. Now the minimum temperature difference is in the middle of the problem, causing a pseudopinch. The best strategy to deal with this type of threshold problem is to treat it as a pinched problem. For the problem in Fig. 16.10, the problem is divided into two parts at the pseudopinch, and the pinch design method is followed. The only complication in applying the pinch design method for such problems is that one-half of the problem (the cold end in Fig. 16.10) will not feature the flexibility offered by matching against utility.

The pinch design method developed earlier followed several rules and guidelines to allow design for minimum utility (or maximum energy recovery) in the minimum number of units. Occasionally, it appears not to be possible to create the appropriate matches because one or other of the design criteria cannot be satisfied. 

The network can now be designed using the pinch design method.The philosophy of the pinch design method is to start at the pinch and move away. At the pinch, the rules for the CP inequality and the number of streams must be obeyed. Above the utility pinch and below the process pinch in Fig. 16.17, there is no problem in applying this philosophy. However, between the two pinches, there is a problem, since designing away from both pinches could lead to a clash where both meet. 

The design method used so far, the pinch design method, creates an... 

For more complex network designs, especially those involving many constraints, mixed equipment specifications, etc., design methods based on the optimization of a reducible structure can be used. 

Structure-based Design Methods to Design HiV-1 Protease Inhibitors... 

Factorial design methods cannot always be applied to QSAR-type studies. For example, i may not be practically possible to make any compounds at all with certain combination of factor values (in contrast to the situation where the factojs are physical properties sucl as temperature or pH, which can be easily varied). Under these circumstances, one woul( like to know which compounds from those that are available should be chosen to give well-balanced set with a wide spread of values in the variable space. D-optimal design i one technique that can be used for such a selection. This technique chooses subsets o... 

M A 1997. Recent Advances in Ligand Design Methods. In Lipkowitz K B and D B Boyd itors) Reviews in Computational Chemistry Volume 11. New York, VCH Publishers, pp. 1-66. 

D J, D W Lewis, C R A Catlow, G J Hutchings and J M Thomas 1997. Designing Templates for Synthesis of Microporous Solids Using De Novo Molecular Design Methods. Journal of Molecular alysis A Chemical 119 415-424. 

Computer-Aided Drug Design Methods and Applications T. J. Perun, C. L. Propst, Eds., Dekker, New York (1989). 

Effect of Axial Dispersion on Column Performance. Another assumption underlying standard design methods is that the gas and the Hquid phases move in plug-flow fashion through the column. In reaHty, considerable departure from this ideal flow assumption exists (4) and different fluid... 

Length of Unused Bed. The constant pattern approximation provides the basis for a very useful and widely used design method based on... 

Design Methods. Improvements ia the ability to predict multicomponent equilibrium and mass-transfer rate performance will allow significant improvements ia the design of new adsorption systems and ia the energy efficiency of existing systems. 

Basic Thermal Design Methods for Heat Exchangers... 

Entrance andExit SpanXireas. The thermal design methods presented assume that the temperature of the sheUside fluid at the entrance end of aU tubes is uniform and the same as the inlet temperature, except for cross-flow heat exchangers. This phenomenon results from the one-dimensional analysis method used in the development of the design equations. In reaUty, the temperature of the sheUside fluid away from the bundle entrance is different from the inlet temperature because heat transfer takes place between the sheUside and tubeside fluids, as the sheUside fluid flows over the tubes to reach the region away from the bundle entrance in the entrance span of the tube bundle. A similar effect takes place in the exit span of the tube bundle (12). 

Melt Index or Melt Viscosity. Melt index describes the flow behavior of a polymer at a specific temperature under specific pressure. If the melt index is low, its melt viscosity or melt flow resistance is high the latter is a term that denotes the resistance of molten polymer to flow when making film, pipe, or containers. ASTM D1238 is the designated method for this test. 

Transfer Coefficient. The design method described depends for its utiHty on the avadabiHty of mass- and heat-transfer coefficients. Typically, ky-a and /i -a are needed. These must be obtained from the standard correlations for mass and heat transfer, from data reported in the Hterature (23—30),... 

Mix Design Methods for Asphalt Concrete MS-2), The Asphalt Institute, 1974. 

Mix Design Methods forMsphaltic Concrete, Manual Series No. 2, The Asphalt Institute, CoUege Park, Md., 1974. 

Whereas there is extensive Hterature on design methods for azeotropic and extractive distillation, much less has been pubUshed on operabiUty and control. It is, however, widely recognized that azeotropic distillation columns are difficult to operate and control because these columns exhibit complex dynamic behavior and parametric sensitivity (2—11). In contrast, extractive distillations do not exhibit such complex behavior and even highly optimized columns are no more difficult to control than ordinary distillation columns producing high purity products (12). 

Computer-aided inhibitor design is a relatively new and powerful approach for the development of novel, potentially potent, nonsubstrate-analogue enzyme inhibitors. Computer-aided methods and biological screening can each lead to new classes of novel inhibitors. However, computer-aided design methods can focus the search for inhibitors, thereby circumventing much of the time-consuming synthetic and natural product purification procedures for those compounds they find unlikely to function as inhibitors. 

---