Systems top-down

Mijatovic D, Eijkel JCT, van den Berg A (2005) Technologies for nanoiluidic systems top-down vs bottom-up-a review. Lab Chip 5 492-500... 

It would be possible to remove all of the heat by pumping cold reflux from the distillate drum to the top of the tower and thus eliminate the cost of the pumparound circuit. Where more than one sidestream is withdrawn, however, it is usually economical to withdraw part of the heat in a pumparoimd reflux system farther down the tower. The following economic factors affect the choice ... 

To determine the procedures you need you should design the system from the top down. Some requirements will apply to many operations such as document control, corrective action, and quality records whereas other requirements may apply to only one operation, such as auditing and management review. A matrix showing this relationship is given in Appendix D. 

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. 

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. 

The sociotechnical systems perspective is essentially top-down, in that it addresses the question of how the implications of management policies at all levels in the organization will affect the likelihood of errors with significant consequences. The sociotechnical systems perspective is therefore concerned with the implications of management and policy on system safety, quality, and productivity. 

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 relationship between the main subsystems and other minor systems is illustrated schematically in Figure 12.4. This places management at the core of the quality system, with the other systems arranged as major and minor satellites that revolve around it. This perspective provides the basis for the Quality System Inspection Technique (QSIT), which the FDA uses for auditing medical device facilities. This is based on a top-down approach, which starts with management controls and then looks at three other key subsystems of Design Controls, Corrective and Preventative Actions (CAPA) and Production and Process Controls. The belief is that by focussing on just these four subsystems, you will actually touch on all the other subsystems and obtain a sufficiently satisfactory overview of the state of compliance of the facility. 

Nanotechnology is the branch of engineering that deals with the manipulation of individual atoms, molecules, and systems smaller than 100 nanometers. Two different methods are envisioned for nanotechnology to buUd nanostructured systems, components, and materials. One method is the top-down approach and the other method is called the bottom-up approach. In the top-down approach the idea is to miniaturize the macroscopic structures, components, and systems toward a nanoscale of the same. In the bottom-up approach the atoms and molecules constituting the building blocks are the starting point to build the desired nanostmcture [96-98]. 

The three hierarchical levels are interconnected by information flowing from the strategic level via the tactical level to the operational level, and the other way around. From upper to the lower level, the information flow is related to the environment on the strategic level, which is the organizational values and norms. However, as Thompson (Thompson, 1967) identified, the tactical control level can allow the operational level to operate as a relatively closed system. The tactical level provides a buffer between the uncertain environment and stability of resources required for uninterrupted production on the operational level. In this way the influences from the external environment on the operational level will be reduced to a minimum. The information flow going from lower to upper level is related to the operational process or transformations. The top down flow provides the restrictions and conditions for the transformation, while the bottom up flow provides information about the status of inputs, outputs, and resources of the transformations. The horizontal information flows are between different control elements on one hierarchical control level. 

A couple of costs are involved in having the FTIR system, number one is the initial price the initial price of the system is about 55,000. That includes a tone key system, the lap top computer, all of the software needed to operate the system, and all of the libraries that I described weapons of mass destruction, toxic industrial chemicals, common chemicals, white powders, drugs, drug precursors, and explosives, ft comes with a carrying case that protects the system in transport, ft comes with a battery pack. There is also a one-year warranty which includes access to the Web site, access to the 247 Reach Back, and then a twenty-four-hour response if your system goes down. We ll have a system to you within... 

Build2-3. Refine it to specify the system by building its local type model of the domain the retrieval mapping is defined top-down. 

In this chapter we describe concrete steps towards building a system or component type specification, to describe how an object behaves in response to any external such as a request to perform some action. The approach here is mostly top-down Chapter 16, How to Implement a Component (p.627) describes how to design the insides of a component, and Chapter 18, How to Reverse-Engineer Types (p.671) covers how to reverse engineer a specification from an existing implementation. 

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