Conceptual modeling

The conceptual modeling is the first step towards formal modeling and analysis of the identified supply chain configuraticMi problem. It elaborates a comprehensive descriptive representation of the supply chain configuration problem and provides 

The purpose of this step is to formalize definition of the supply chain configuration problem and gathering of appropriate data. The main tasks are (1) definition of supply chain configuration goals, relevant concepts and processes (2) data structuring and (3) data gathering from heterogeneous data sources. 

A data model is derived from the conceptual model to serve as the basis for data integration. The data model defines all objects, parameters, and costs relevant to the specific supply chain configuration problem. Values are assigned to these 

Memory depth (i.e., how many historical records are available) of transactional data is also important. For additional information on data processing issues, data types, and their sources readers are referred to Shapiro (2006). 

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The corresponding fiinctions i-, Xj etc. then define what are known as the normal coordinates of vibration, and the Hamiltonian can be written in tenns of these in precisely the fonn given by equation (AT 1.69). witli the caveat that each tenn refers not to the coordinates of a single particle, but rather to independent coordinates that involve the collective motion of many particles. An additional distinction is that treatment of the vibrational problem does not involve the complications of antisymmetry associated with identical fennions and the Pauli exclusion prmciple. Products of the nonnal coordinate fiinctions neveitlieless describe all vibrational states of the molecule (both ground and excited) in very much the same way that the product states of single-electron fiinctions describe the electronic states, although it must be emphasized that one model is based on independent motion and the other on collective motion, which are qualitatively very different. Neither model faithfully represents reality, but each serves as an extremely usefiil conceptual model and a basis for more accurate calculations. 

A fundamental difference exists between the assumptions of the homogeneous and porous membrane models. For the homogeneous models, it is assumed that the membrane is nonporous, that is, transport takes place between the interstitial spaces of the polymer chains or polymer nodules, usually by diffusion. For the porous models, it is assumed that transport takes place through pores that mn the length of the membrane barrier layer. As a result, transport can occur by both diffusion and convection through the pores. Whereas both conceptual models have had some success in predicting RO separations, the question of whether an RO membrane is truly homogeneous, ie, has no pores, or is porous, is still a point of debate. No available technique can definitively answer this question. Two models, one nonporous and diffusion-based, the other pore-based, are discussed herein. 

Beeler defined the broad scope of computer experiments as follows Any conceptual model whose definition can be represented as a unique branching sequence of arithmetical and logical decision steps can be analysed in a computer experiment... The utility of the computer... springs mainly from its computational speed. But that utility goes further as Beeler says, conventional analytical treatments of many-body aspects of materials problems run into awkward mathematical problems computer experiments bypass these problems. 

Upon completion of both the preliminary and detailed site investigation, a conceptual model can be prepared. A conceptual model is essentially a site model which includes all of the information that has been acquired for the site from both preliminary and detailed investigations, as well as other investigations not directly related to the site. The conceptual model can be anything from simple diagrams to detailed computer simulations, depending ujran the complexity of the site. The model must be continually updated to include new information as it is developed. 

Once the conceptual model is operating, it can be utilized to help develop a technically sound, cost-effective recovery and treatment system. Potential uses for a conceptual model include provision of continual upniates of project developments, provision of a yardstick to measure what has been done and what needs to be done, and helping prioritize areas for Corrective Action. Ultimately, the principal use for a conceptual model is to help determine what Corrective Actions or alternatives are applicable to the site. 

Fig. 2.14. Atomic level relative mass motion is an expected consequence of plastic deformation. Dremin and Breusov [68D01] have described a conceptual model of such behavior (called a Roller Model ) to explain submicrosecond structural and chemical transformations under shock compression.

Although it is probably not possible at present to develop a completely satisfactory quantitative model, a conceptual model that identifies the critical processes can be developed. First, it is apparent that before significant chemical reaction can occur substantial modification must be induced by the shock-compression process. With present knowledge, the problem is one of mechanical deformation, rather than one of chemistry. The materials studies... 

In most cases of interest, shock-induced chemical reactions in solids are studied in mixtures of powders of the potential reactants. In the earlier description of conceptual models it was emphasized that the pores provide space in which the potential reactants can be more intimately mixed in order... 

This chapter presents detailed and thorough studies of chemical synthesis in three quite different chemical systems zinc ferrite, intermetallic, and metal oxide. In addition to different reaction types (oxide-oxide, metal-metal, and metal oxide), the systems have quite different heats of reaction. The oxide-oxide system has no heat of reaction, while the intermetallic has a significant, but modest, heat of reaction. The metal oxide system has a very large heat of reaction. The various observations appear to be consistent with the proposed conceptual models involving configuration, activation, mixing, and heating required to describe the mechanisms of shock-induced solid state chemistry. 

While CAM-6 is somewhat limited in its ability to perform large-scale simulations of physical systems (it is a much less capable system than its follow-on, the CAM-8, for example see discussion below), its fundamental historical importance cannot be overstated. CAM-6 allowed researchers to directly experience, for the first time and in real time, the evolution of CA systems theretofore undertsood only as purely conceptual models. Margolus and Toffoli recall that when Pomeau, one of... 

Figure 1. Conceptual model illustrating examples of major anthropogenic contaminant sources and contaminants, their distribution within the abiotic environmental media, their movement into biota with potential food chain contamination, and potential effects at the organismal, population, conmiunity and ecosystem level of organization.

Fig. 9-3 Conceptual model to describe the interaction between chemical weathering of bedrock and down-slope transport of solid erosion products. It is assumed that chemical weathering is required to generate loose solid erosion products of the bedrock. Solid curve portrays a hypothetical relationship between soil thickness and rate of chemical weathering of bedrock. Dotted lines correspond to different potential transport capacities. Low potential transport capacity is expected on a flat terrain, whereas high transport is expected on steep terrain. For moderate capacity, C and F are equilibrium points. (Modified with permission from R. F. Stallard, River chemistry, geology, geomorphology, and soils in the Amazon and Orinoco basins. In J. I. Drever, ed. (1985), "The Chemistry of Weathering," D. Reidel Publishing Co., Dordrecht, The Netherlands.)...

The period 1930-1980s may be the golden age for the growth of qualitative theories and conceptual models. As is well known, the frontier molecular orbital theory [1-3], Woodward-Hoffmann rules [4, 5], and the resonance theory [6] have equipped chemists well for rationalizing and predicting pericyclic reaction mechanisms or molecular properties with fundamental concepts such as orbital symmetry and hybridization. Remarkable advances in aeative synthesis and fine characterization during recent years appeal for new conceptual models. 

Conceptual model of conventional Cl combustion characterized by a sequence of processes occurring in a fully developed reacting jet. (From Dec, A Conceptual Model of DI Diesel Combustion Based on Laser Sheet Imaging, SAE, 970873,1997. With permission.)... 

Berger, B.R. and Eimon, R.I. (1983) Conceptual models of epithermal precious metal deposits. In Shanks, W.C. Ill (ed.), Cameron Volume on Unconventional Mineral Deposits. New York Society of Mining Engineers of the American Institute of Mining, Metallurgical and Petroleum Engineers Inc., pp. 191-205. 

In this example it is required to model the behaviour of the mixing vessel according to the conceptual models indicated below. 

Davidson, E. A., Keller, M., Erickson, H. E., Verchot, L. V., and Veldkamp, E. (2000). Testing a conceptual model of soil emissions of nitrous and nitric oxide. Bioscience 50, 667-680. 

Combining ammonium immobilization rates with estimates of C inputs and C maintenance requirement (proportional to the active microbial biomass), whose difference gave C available for microbial growth from the same experimental system (111,128), it allowed the building up of a conceptual model for C and N... 

In experiments with lowland rice Oiyzci saliva L.) it was found that roots quickly exhausted available sources of P and sub.sequently exploited the acid-soluble pool with small amounts deriving from the alkaline soluble pool (18). More recalcitrant forms of P were not utilized. The zone of net P depletion was 4-6 mm wide and showed accumulation in some P pools giving rather complex concentration profiles in the rhizosphere. Several mechanisms for P solubilization could be invoked in a conceptual model to describe this behavior. However using a mathematical model with independently measured parameters (19), it was shown that it could be accounted for solely by root-induced acidification. The acidification resulted from H" produced during the oxidation of Fe by Oi released from roots into the anaerobic rhizosphere as well as from cation/anion imbalances in ion uptake (18). Rice was shown to depend on root-induced acidification for more than 80% of its P uptake. 

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