In this paper, we examine a class of convex problems of Bolza type, involving a time delay in the state. It encompasses a variety of time-delay problems arising in the calculus of variations and optimal control. A dua...
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In this paper, we examine a class of convex problems of Bolza type, involving a time delay in the state. It encompasses a variety of time-delay problems arising in the calculus of variations and optimal control. A duality analysis is carried out which, among other things, leads to a characterization of minimizers in terms of the Euler-Lagrange inclusion. The results obtained improve in significant respects on what is achievable by techniques previously employed, based on elimination of the time delay by introduction of an infinite-dimensional state space or on the method of steps.
The theory of flow similarity has not been well established for granular flows, in contrast to the case for conventional fluids, owing to a lack of reliable and general constitutive laws for their continuum descrip- t...
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The theory of flow similarity has not been well established for granular flows, in contrast to the case for conventional fluids, owing to a lack of reliable and general constitutive laws for their continuum descrip- tion. A rigorous investigation of the similarity of velocity fields in different granular systems would he valuable to theoretical studies. However, experimental measurements face technological and physical problems. Numerical simulations that employ the discrete element method （DEM） may be an alterna- tive to experiments by providing similar results, where quantitative analysis could be implemented with virtually no limitation. In this study, the similarity of velocity fields is investigated for the rolling regime of rotating drums by conducting simulations based on the DEM and using graphics processing units. For a constant Froude number, it is found that the particle-to-drum size ratio plays a dominant role in the determination of the velocity field, while the velocity field is much more sensitive to some material properties than to others. The implications of these findings are discussed in terms of establishing theoretical similarity laws for granular flows.
This paper presents two attack strategies designed to evade detection in ADMM-based systems by preventing significant changes to the residual during the attacked iteration. While many detection algorithms focus on ide...
Recently, EMMS-based models are being widely applied in simulations of high-throughput circulating fluidized beds （CFBs） with fine particles. Its use for low flux systems, such as CFB boiler （CFBB）, still remains ...
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Recently, EMMS-based models are being widely applied in simulations of high-throughput circulating fluidized beds （CFBs） with fine particles. Its use for low flux systems, such as CFB boiler （CFBB）, still remains unexplored. In this work, it has been found that the original definition of cluster diameter in EMMS model is unsuitable for simulations of the CFB boiler with low solids flux. To remedy this, we propose a new model of cluster diameter. The EMMS-based drag model （EMMS/matrix model） with this revised cluster definition is validated through the computational fluid dynamics （CFD） simulation of a CFB boiler.
The Semantic Web provides mechanisms to interlink data in a fast and efficient way and build complex information networks. However, one of the most important features missing for industrial application is version cont...
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作者：
Groves, D.M.Exxon Chemical Co
Process Control Systems Baytown TX USA Exxon Chemical Co Process Control Systems Baytown TX USA
This paper examines the retrofit of a sophisticated control system into an existing petrochemical complex. Exxon has been pursuing modern processcontrolsystems development since the early 1960's. These systems g...
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ISBN:
(纸本)0876648014
This paper examines the retrofit of a sophisticated control system into an existing petrochemical complex. Exxon has been pursuing modern processcontrolsystems development since the early 1960's. These systems generally include improved instrumentation, control computers, and the expanded use of analyzers, all aimed at improved higher level control. In the 1963-1965 time frame, Exxon began to explore the use of electronic instrumentation coupled with computers.
This paper is concerned with the design and implementation of an integrated software package for the optimisation of general multipurpose batch and semi-continuous plants. In particular, we describe a sophisticated gr...
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This paper is concerned with the design and implementation of an integrated software package for the optimisation of general multipurpose batch and semi-continuous plants. In particular, we describe a sophisticated graphical user interface that supports the rapid specification of scheduling, planning, design and retrofit problems in an error-free manner. These problems are posed graphically and solved under a unified framework based on the state-task network process representation and a general characterisation of all production resources, such as processing and storage equipment, utilities and manpower. This representation facilitates the specification of processing recipes of arbitrary complexity, involving material recyles, shared intermediates, batch splitting and mixing and multiple routes to the same end-product. The architecture employed shields the users from the complex mathematical. models and solution procedures that are employed, freeing lip their time for problem specification and results analysis.
As an approach to cope with rising volatility of sales markets and increasingly shorter development cycles, process industries are expecting much from the concept of modularization. However, a topic that is still rare...
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Recent developments on the application of artificial intelligence (Al) concepts and techniques for the automation of chemical process fault diagnosis has met with some success. However, the process of developing such ...
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Recent developments on the application of artificial intelligence (Al) concepts and techniques for the automation of chemical process fault diagnosis has met with some success. However, the process of developing such systems, called knowledge engineering, is time-consuming and expensive involving specialized labour. This bottleneck presents a serious barrier that must be overcome if the benefits of Al-based approaches are to be realized at large in the process industry. Towards that goal, we present an analysis of the knowledge engineeringprocess in the context of process diagnosis and a possible solution strategy. By viewing the knowledge engineering activity at different levels of abstraction, one is able to identify how the different aspects of the bottleneck emerge and also clarify methodological issues from formalization- and implementation-related ones. The analysis suggests that a specialized environment or shell, that already possesses the diagnostic methodology and the related modelling constructs, is the natural way of circumventing the bottleneck. As a potential knowledge core of such a shell, a diagnostic methodology that has the characteristics to facilitate rapid prototyping, easy modification, and maintenance of diagnostic expert systems is described.
For most use cases, the Semantic Web provides essential mechanisms to interlink data in a fast and efficient way. However, it is still not widely accepted in industry since some important features are not mature enoug...
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For most use cases, the Semantic Web provides essential mechanisms to interlink data in a fast and efficient way. However, it is still not widely accepted in industry since some important features are not mature enough. Requirements include easier model transformation and access to dynamic data. One of the most missing important features is version control which would make it possible to record changes in a way that they can be rolled back at any time. Recent version control system are not very well integrated into the Semantic Web. This paper shows a novel way of dealing with version control for Linked Data. It presents R43ples as an approach using named graphs to semantically store the differences between revisions. Furthermore it allows direct access and manipulation of revisions with SPARQL. Thus, the access is almost transparent for the clients which can still use known SPARQL queries enhanced with some additional keywords. A prototypical implementation of the system shows a proof of concept and performance considerations. Copyright is held by the author/owner(s).
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