Simplified approaches

Many simplified procedures can be used for seismic design and re-evaluation purposes in the solution of special problems for example  

However, any simplified approach needs to be validated for the application of interest, as it is usually dependent on engineering judgement. 

---

D. B. Nash and co-workers, "A Simplified Approach to Heat Exchanger Network Analysis," AIChE 85th National Meeting, Philadelphia, Pa., June 1978. 

This example illustrates the simplified approach to film blowing. Unfortunately in practice the situation is more complex in that the film thickness is influenced by draw-down, relaxation of induced stresses/strains and melt flow phenomena such as die swell. In fact the situation is similar to that described for blow moulding (see below) and the type of analysis outlined in that section could be used to allow for the effects of die swell. However, since the most practical problems in film blowing require iterative type solutions involving melt flow characteristics, volume flow rates, swell ratios, etc the study of these is delayed until Chapter 5 where a more rigorous approach to polymer flow has been adopted. 

Roliani, S. and Bourne, J., 1990a. A simplified approach to the operation of a batch crystallizer. Canadian Journal of Chemical Engineering, 45, 3457-3466. 

The combustion-flow interactions should be central in the computation of combustion-generated flow fields. This interaction is fundamentally multidimensional, and can only be computed by the most sophisticated numerical methods. A simpler approach is only possible if the concept of a gas explosion is drastically simplified. The consequence is that the fundamental mechanism of blast generation, the combustion-flow interaction, cannot be modeled with the simplified approach. In this case flame propagation must be formalized as a heat-addition zone that propagates at some prescribed speed. 

Strehlow, R. A. 1975. Blast waves generated by constant velocity flames A simplified approach. Combustion and Flame. 24 257-261. 

Radiation effects from a flash fire are now fully determined if vapor cloud composition, as well as the geometry of the flame front (dependent on time), is known. Vapor cloud composition is, of course, place- and time-dependent, and the shape of flame front will greatly depend on cloud shape and ignition site within the cloud. The total radiation intercepted by an object equals the surmnation of contributions by all successive flame positions during flame propagation. This is an impossible value to compute with the simplified approach just described. Because there are many uncertainties (e.g., cloud composition, location of ignition site) which greatly influence the final result, a conservative approach is recommended for practical applications ... 

A very simplified approach exists in the literature in which the exact LDOS are replaced by constant densities of states with the same first three... 

The efficient heat pump reduces energy use by 1,676 kWh per year on average. Is the efficient model heat pump a good investment Suppose the incremental cost of the efficient unit, as compared with the less efficient unit, is 1,000, and electricity cost 10 cents per kWh. With this price of electricity, the efficient heat pump reduces electricity costs by 167.60 per year. Taking a simplified approach for purposes of illustration and assuming that each unit lasts indefinitely and has no repair, maintenance, or replacement costs, and ignoring possible tax effects, the internal rate of return may be calculated as 1,000= 167.60/r, which is 16.76 percent per year. If the household can borrow money at, say, 10 percent per year and earn 16.76 percent, the investment makes economic sense. If we assume a 10 percent discount rate, the present value of the investment is 1,676, which exceeds the initial investment cost. The net present value is 676, which indicates that the investment is feasible. 

When the first edition of Chemistry of Petrochemical Processes was written, the intention was to introduce to the users a simplified approach to a diversified subject dealing with the chemistry and technology of various petroleum and petrochemical process. It reviewed the mechanisms of many reactions as well as the operational parameters (temperature, pressure, residence times, etc.) that directly effect products yields and composition. To enable the readers to follow the flow of the reactants and products, the processes were illustrated with simplified flow diagrams. 

Figure 15.5 shows the ideal open cycle for the gas turbine that is based on the Brayton Cycle. By assuming that the chemical energy released on combustion is equivalent to a transfer of heat at constant pressure to a working fluid of constant specific heat, this simplified approach allows the actual process to be compared with the ideal, and is represented in Figure 15.5 by a broken line. The processes for compression 1-2 and expansion 3-4 are irreversible adiabatic and differ, as shown from the ideal isentropic processes between the same pressures P and P2 -... 

Apparent creep modulus. The concept of an apparent modulus is a convenient method for expressing creep, because it takes into account the initial strain for an applied stress plus the amount of deformation or strain that occurs over time. Thus, the apparent modulus Ea is calculated in a very simplified approach as ... 

In a simplified approach the first step in analyzing any product is to determine the loads to which it will be subjected. These loads will generally fall into one of two categories, directly applied loads and strain-induced loads. Directly applied loads are usually easy to understand. They are defined loads that are applied to defined areas of the product, whether they are concentrated at a point, line, or boundary or distributed over an area. The magnitude and direction of these loads are known or can easily be determined from the service conditions. Figure 3-2 shows examples of directly applied loads. 

Selecting an optimal material for a given product must obviously be based on analysis of the requirements to be met. A simplified approach involves comparing the specific service requirements to the potential properties of a plastic. What follows is a simplified but practical material-selection approach. This longhand system is a basis of the fastest computerized databases. 

More recently, Rosen (R3), Spalding (S5), and Johnson and Nachbar (J4) have considered a simplified approach using the analysis of laminar-flame propagation velocities. According to these investigators, the principal exothermic reactions occur in the gas phase. Some of the heat liberated by these reactions is then transferred back to the solid surface to sustain the endothermic surface-gasification processes. Thus, the temperature profile within the reactive zone is quite similar to that of Rice and Crawford. However, gasification of the solid surface is assumed to be endothermic, while exothermic reactions were considered in the studies discussed previously. 

Sadler [76] analysed the outline of the crystal edges and found that the lateral surface tension compatible with such a curvature would be a 1 — 3 kT/. Although he used a very simplified approach, it seems unlikely that its assumptions could lead to a a 20 kT/<7> as predicted by the LH theory. 

A simplified approach to the glass-transition temperature of the composite can be based on the thermal expansion curves of Fig. 2. The elastic filler (f) exhibits a... 

Whilst the calculation of the radiant heat flux from a gas to an adjoining surface embraces inherent spectral and directional effects, a simplified approach has been developed by Hottel and Manglesdorf 54, which involves the determination of radiation emission from a hemispherical mass of gas of radius L, at temperature 7, ... 

The following treatment, based on the simplified approach suggested by Pramtu involves the following three assumptions ... 

The equation should be compared with equation 11.49 obtained using PrandtTs simplified approach to boundary layer theory which also disregards the existence of the buffer layer ... 

Moshiri, E. Computer Modeling of Photochemical Ozone Formation A Simplified Approach Ph.D. Thesis Portland State University Portland, OR, 1984 1-211. 

The simplified theory is adequate to obtain qualitative agreement with experiment [1,16]. Comparisons between the simplified and more advanced versions of the theory show excellent agreement for the dominant (electronic) contribution to the time-dependent dipole moment, except during the initial excitation, where the k states are coupled by the laser field [17]. The contributions to the dipole from the heavy holes and light holes are not included in the simplified approach. This causes no difficulty in the ADQW because the holes are trapped and do not make a major contribution to the dynamics [1]. This assumption may not be valid in the more general case of superlattices, as discussed below. 

Snider, G. L. Interpretation of the Arterial Oxygen and Carbon Dioxide Partial Pressures A Simplified Approach for Bedside Use. Chest (1973), 6, 801 - 806. 

Hence, we find two energy levels for the diatomic molecule where the electron can reside, one bonding and the other antibonding. This simplified approach does not describe the situation quantitatively too well, but in a qualitative sense it captures all the important effects. In the following we consider a few illustrative cases in the limit where the overlap S is small (this is the usual approximation for elementary work). In this limit Eq. (15) reduces to ... 

In Eqs. (27) and (28), p is the contribution of the substrate water molecules, p that of the adsorbate polar head, and p that of the hydrophobic moiety of the adsorbed molecules. Consistently, 8i, 82, and 83 are the effective local permittivities of the free surface of water and of the regions in the vicinity of the polar head and of the hydrophobic group, respectively. The models have been used in a number of papers on adsorbed monolayers and on short-chain substances soluble in water. " Vogel and Mobius have presented a similar but more simplified approach in which p is split into two components only. " Recently some improvements to the analysis using Eq. (27) have been proposed. " An alternative approach suggesting the possibility of finding the values of the orientation angle of the adsorbate molecules instead of local permittivities has been also proposed.""... 

Although the extended ab initio atomistic thermodynamics approach provides an exact expression for the interfacial stability, the formalism requires self-consistent modeling of the entire electrochemical system, or electrode/electrolyte interface, exceeding presently available computational capabilities. Therefore, certain assumptions had to be made that reduce the effort to the calculation of the electrode surface only. Even with this simplified approach, which has been applied to the two examples discussed in this chapter, the qualitative behavior can be reproduced. 

Lang, H. J. (1948) Chem. Eng., NY 55 (June) 112. Simplified approach to preliminary cost estimates. 

Lang, H.J. Simplified Approach to Preliminary Cost Estimates, Chemical Engineering, June,... 

McLeod, H.O., Jr. "A Simplified Approach to Design of Fracturing Treatments Using High Viscosity Crosslinked Fluids," SPE/DOE paper 11614, 1983 SPE/DOE Symposium on Low Permeability, Denver, March 14 16. 

Pietrogrande, M.C., Marchetti, N., Tosi, A., Dondi, E, Righetti, P.G. (2005). Decoding two-dimensional polyacrylamide gel electrophoresis complex maps by autocovariance function a simplified approach for proteomics. Electrophoresis 26, 2739-2748. 

---