Bottom-up

Figure 10.3-34. The plajiiiing of a synthesis is neither a classical bottom-up nor a top-down search, ft is an array of different methods for searching and planning, applied In both the retrosynthetic and the synthetic directions.

These absorptions are ascribed to n-n transitions, that is, transitions of an electron from the highest occupied n molecular orbital (HOMO) to the lowest unoccupied n molecular orbital (LUMO). One can decide which orbitals are the HOMO and LUMO by filling electrons into the molecular energy level diagram from the bottom up, two electrons to each molecular orbital. The number of electrons is the number of sp carbon atoms contributing to the n system of a neuhal polyalkene, two for each double bond. In ethylene, there is only one occupied MO and one unoccupied MO. The occupied orbital in ethylene is p below the energy level represented by ot, and the unoccupied orbital is p above it. The separation between the only possibilities for the HOMO and LUMO is 2.00p. 

Table 2. Some Approaches in Reductive (Top Down) and Synthetic (Bottom Up) Nanofabrication...

All stage-to-stage methods that work from both ends of the column toward the middle suffer from two other disadvantages. First, the top-down and the bottom-up calculations must me somewhere in the column. Usually the mesh is made at a feed stage, and if more than one feed stage exists, a choice of mesh point must be made for each component. When the components vary widely in volatility, the same mesh point cannot be used for all components if serious numerical difficulties are to be avoided. Second, arbitrary procedures must be set up to handle nondlstrihuted components. (A nondistributed component is one whose concentration in one of the end-product streams is smaller than the smallest number carried by the computer.) In the LM and TG equations, the concentrations for these components do not natur ly take on nonzero values at the proper point as the calculations proceed through the column. 

Top-down calculations for tbe example problem are shown in Table 13-10 and bottom-up calculations in Table 13-11. Top-down and bottom-up calculations have provided values of and respectively. For a bubble-... 

Micro-scaling or bottom up approach to quality costs, where it is possible to calculate the cost of losses involved in manufacture and due to returns and/or claims. This method requires a great deal of experience and relies on the availability of detailed cost data throughout a product s life-cycle. While this is a crucial activity for a business, it is also not a practical approach for estimating the quality cost for product in the early stages of product development. 

To determine the minimal cutsets of a fault tree, the tree is first translated into its equivalent Boolean equations and then either the "top-down" or "bottom-up" substitution method is used. The methods are straightforward and involve substituting and expanding Boolean expressions Two Boolean laws, the distributive law and the law of absorption (Table 2.1-1), are used to remove superfluous items. 

The bottom-up method uses the same substitution and expansion techniques, except that now, the operation begins at the bottom of the tree and proceeds up. Equations containing only basic failures are successively substituted for higher faults. The bottom-up approach can be more laborious and time-consuming however, the minimal cutsets are now, 1 obtained for every intermediate fault as well as the top event. 

OD -T alpha-lies, control, fault-tree description, failure data AND OR NOT K-of- N Bottom-up modularization and decompo-dtion of fault tree into t>est modular nepresentation Top event probability, time dependence, c s, r rCLs, and Linceitainty Option of not generating minimal cut >ets forquali ing fault ree IBM 360/370 Fortran IV, Available j from Software < enter... 

WAMCUT/ 1500 primary events Bottom up Based on both cutset Not option caii generate <... 

MOCUS implemented the Fussell algorithm (Fussell, 1974) for top-down solutions of the fault tree. This algorithm was used in ALLCUT and was modified to be bottom-up in WAMCE T. While cutsets are valuable for qualitative and quantitative purposes, they are not compact. They are thousands of trains (AND sequences) connected to one OR gate. 

The member countries participate on an a la carte principle, and activities are launched using a bottom-up approach. One of its main features is its built-in flexibility. This concept clearly meets a growing demand, and in addition, it complements rhe community programs. 

How do you then design an effective system There are several techniques you can use. Failure Modes and Effect Analysis (FMEA), Fault Tree Analysis (FTA), and Theory of Constraints (TOC) are but three. The FMEA is a bottom-up approach, the FTA a top-down approach, and TOC a holistic approach. 

The FMEA approach is a bottom-up approach, looking at component failures and establishing their effect on the system. An alternative approach is to use a top-down approach such as Fault Tree Analysis to postulate system failure modes and establish which processes, procedures, or activities are likely to cause such failures. 

Design the quality system from the top down by analyzing your business processes and then implement from the bottom up, starting with customer complaints. 

Some of this information is presented in the form of very specific examples, used to illustrate a range of approaches and methods. TTiis range is not intended to be all-inclusive your company s precise oiganization may not be represented here. However, every effort has been made to address several common structures, including centralized and decentralized operations and "top-down" and "bottom-up" management structures. 

If you find numerous self-contained systems, this may imply (a) that your company s methods are more likely to be driven from the bottom up than from the top down, and (b) that there maybe some redundancy, overlap, or conflict among multiple systems devoted to the same issue. 

Baffles that extend from the liquid level dowai, but not to, the tank bottom allow heavy swrirling action in the bottom of the tank, but no vortex at the top. Wdien baffles extend from the bottom up, but not to the liquid level, some v ortex and sw irling action will take place at the top. 

Let us now shift our focus and consider the bottom-up , or kinetic theory, approach to fluid dynamics. Kinetic theory describes fluids by assuming that they are made up of a large number of individual atoms or molecules, each subject to the laws of... 

The term collectivism has sometimes been used to distinguish this AL philosophy from the more traditional top down and bottom up philosophies. Collectivism embodies the belief that in order to properly understand complex systems, such systems must be viewed as coherent wholes whose open-ended evolution is continuously fueled by nonlinear feedback between their macroscopic states and microscopic constituents. It is neither completely reductionist (which seeks only to decompose a system into its primitive components), nor completely synthesist (which seeks to synthesize the system out of its constituent parts but neglects the feedback between emerging levels). 

Collectivism is thus distinct from both the top-down reductionist approach traditionally favored by most physicists (system as a simple edifice of its microscopic parts), and the more recent neural-net-like bottom-up approach favored by connec-tionists (system as a synthesis of its constituent parts). The nonlinear inter-level feedback loop that makes up the collective is what makes a traditional linear analysis of such systems difficult, if not impossible. 

The dynamic,s underlying EINSTein is patterned after mobile CA rules, and are somewhat reminiscent of Braitenberg s Vehicles [brait84]. Specifically, EINSTein takes a artificial-life-like bottom-up, synthesist approach to the modeling of combat, rather than the more traditional top-down, or reductionist approach,... 

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