Application Performance Modeling

One quick way to tell whether Ts riai is the most important factor or whether other issues should be explored is to quantitatively test empirical speed-up curves for consistency with Amdahl s law. If they are not, then some factor other than is at work. In that case, further investigation will be 

It is impossible to derive a general model that applies to all application domains and all computer systems. In theory, one can predict performance from first principles, but this would require a detailed understanding of every part of the computation and how its memory access (data communication) patterns interact with the computer s hardware and operating system. Except for small computational kernels, it is not feasible to acquire such understanding. In practice, a more satisfactory approach is to construct a fairly high level model using approximate functional forms for the amount of computation, load balance, and overheads. 

As an example, we outline a model of the performance of a Hartree-Fock (HE) algorithm in which the problem size is N, the number of basis functions. In other applications, the problem size could be the number of atoms, the number of particles in a simulation, and so on. The total execution time for the HE algorithm can be modeled as follows  

This simple modified Amdahl s law illustrates the incentives for optimal load balancing. The case(0,3000,0) corresponds to a hypothetical situation in which there is no serial execution time and no overhead for communication. The deviation from linear speed-up in this case (about 10%) is due only to load imbalance. 

It is instructive to develop models like this and to define each of the parameters in a way that simulates a specific application or group of applications. MPP users can employ these performance models, provided they are reasonably accurate, to predict both how an application will perform on a new MPP system and the time to solution of a particular problem. More detailed analyses of performance characteristics can be applied, and some of these are discussed in the sections that follow. 

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Metal monoliths show good thermal characteristics. A typical support with herringbone channels made from Fecralloy performed satisfactory in automotive applications [27]. Modeling showed that overall heat transfer was about 2 times higher than for conventional pellets [28,29]. Hence, there is potential for structured catalysts for gas-phase catalytic processes in multitubular reactors. 

A model which is consistent with the chemistry described previously has been developed to predict the performance of ZSM-5 in an FGG unit. Application of this model allows the user to take full advantage of ZSM-5 s flexibility for specific applications. The model has been used in many commercial applications to determine the catalyst makeup rate required to achieve a given octane boost. It has also been used to tailor the catalyst makeup strategy to obtain a desired octane boost in a given period of time. 

One of the main applications of the ZSM-5 performance model is to determine the optimal catalyst makeup strategy to achieve a desired octane boost in a required period of time. Since ZSM-5 is used primarily as an additive, the catalyst makeup policy can be tailored to fit the refiner s needs. 

The theoretical models cannot predict flux rates. Plant-design parameters must be obtained from laboratory testing, pilot-plant data, or in the case of established applications, performance of operating plants. 

Let us perform modelling with the application of just these parameters. Let us first estimate the parametric sensitivity of the steady-state kinetic dependences for CO oxidation over Ir(110) to variations in the rate constant. We will assume that k = k = 0.36 x 1021 molecules cm2 s 1 (the number of CO molecule collisions per unit time on unit surface) and k° 2 = 1013 s 1. The desorption constant of 02 was not varied. The parameters E3, Eif and k°A... 

Chasman and co-workers derived the time complexity of each combination of Hamiltonian evaluation and time integration method for both serial and parallel computers. Table 1 shows their results for systems of two and three dimensions. This time complexity can be used to develop a computational cost model of their application. A full analysis of the communication properties of their application could be developed to derive a complete performance model. This, in turn, could be used to determine the time to completion for a given problem on a given computer or, alternatively, the performance of a given problem on a new parallel supercomputer. 

By contrast, when the mass transfer resistances and/or axial dispersion are considered, there is no analytical solution for an SMB operated under nonlinear isotherm conditions. A numerical solution of the applicable mathematical model must be used instead to calculate the performance of the SMB, to simulate the influence of the various design and operating parameters, and to search for the optimum flow rates and switching time that give the desired results. In this quest, the selection as a starting point of the optimum set of flow rates and switching time derived from the equilibrium theory permits a considerable reduction of the number of calculations. As discussed earlier by Ruthven and Ching [27], four... 

Microsoft Office allows the option to record macros for performing repetitive tasks. Although macros are somewhat limited for the development of true VBA applications, macro recording can be used effectively to learn VBA or create templates of code that can be generalized with the addition of variables. If VBA for Microsoft Office is enabled, you only need to press alt-fi i to open the VBA Integrated Development Environment (IDE). A search of the on-line help for Application Object will provide an interactive object hierarchy that describes (with detailed code examples) each object or collection. There are literally thousands of objects within the Microsoft Office application object models. Another very useful tool within the VBA environment is the Object Browser, which can be invoked with the F2 key. The Object Browser can be particularly useful to learn the objects of external components that have been referenced from within VB or VBA. This method is an excellent way to get started with new object types and follow along with the documentation. An example is shown in Figure 18.3 from the Excel 2000 VBA IDE. In this example, the Excel is the automation client and Sciex Analyst method component... 

Next, for each integrator, a set of link types must be defined. These are based on the document contents models and the additional relationships defined in the document contents and the inter-document relationship model. Inter-document relationships that are already defined in the application domain models (within ontologies as well as document contents and relationship models) can be transformed into link types. This can be done automatically if the application models are formal. Otherwise, a manual translation has to be performed. 

The specification of fine-grained interdocument relationships in the application domain model is not sufficient to derive integration rules. Currently, the tool builder has to perform the definition of related patterns manually with the help of a domain expert. Whether it is possible to extend the apphcation domain model without making it too complex and too tool-related remains an open issue. 

The paper machine example first introduced in Section 10.1.1 reflects open-loop in CD control data. Application of model-based CD control performance calculations is simplified for this case as U = 0 while the results establish an upper limit of improvement expectations from a potential CD control implementation. Following the procedure summarized in the block diagram of Figure 10.24 simulation calculations provide = 0.0644... 

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