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103.
This paper reports on the experience gained in solving large combinatorial problems by using the Outer-Approximation /Equality-Relaxation (OA/ER) algorithm in two multilevel MINLP strategies. The first one is a Linked Multilevel Hierarchical Strategy (LMHS) and the second one is a Reduced Integer Space (RIS) strategy. Both strategies are used to decompose the original MINLP problem in a hierarchical manner into several MINLP levels that are much easier to solve than the original one. While the first LMHS strategy can be applied to problems that contain only simple mixed-integer constraints, e.g. standard dimensions, the RIS strategy can be used to solve problems with more complex mixed-integer constraints, e.g. different design equations for alternative units. The LMHS strategy is rigorous and can solve convex problems to global optimal solutions. On the other hand, when the RIS strategy is applied for the solution of large combinatorial problems, the global optimality cannot be guaranteed, but very good solutions can be obtained. The synthesis problem of a roller steel gate for a hydroelectric power station with 19623 binary variables is presented to illustrate the LMHS strategy, whilst the synthesis problem of a heat exchanger network comprising different types of exchangers with 1782 binary variables is presented to present the RIS strategy. 相似文献
104.
Hasan Atiyeh Zdravko Duvnjak 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2003,78(10):1068-1074
The mutant Saccharomyces cerevisiae ATCC 36858 was used in the production of ethanol and/or fructose from synthetic media in batch processes with raffinose, melibiose or sucrose. The mutant was able to hydrolyze all the sugars used and to selectively ferment glucose and galactose to ethanol while fructose accumulated in the fermentation medium. The fructose yield was above 89% of the theoretical value in the media with either raffinose or sucrose, when initial concentrations were between 131.5 g dm?3 and 242.0 g dm?3. The ethanol yields were 82% and 77% of the theoretical values in the media with melibiose and sucrose, respectively, and about 72% of the theoretical value when raffinose was used. The fructose fraction in the carbohydrate content of the produced syrups was more than 96% when raffinose concentration was below 189.1 g dm?3. However, even at a sucrose concentration of 187.9 g dm?3, the produced syrup contained 100% fructose. Some oligosaccharides were also produced in all tested media. The produced oligosaccharides were consumed by the end of the fermentation process. These findings can be useful in the production of ethanol and high fructose syrups using raw materials based on sucrose and raffinose such as molasses. Copyright © 2003 Society of Chemical Industry 相似文献
105.
The generalized coordinates partitioning is a well-known procedure that can be applied in the framework of a numerical integration
of the DAE systems. However, although the procedure proves to be a very useful tool, it is known that an optimization algorithm
for the coordinates partitioning is needed to obtain the best performance. In the paper, the optimized partitioning of the
generalized coordinates is revisited in the context of a numerical forward dynamics of the holonomic and non-holonomic multibody
systems. After a short presentation of the geometric background of the optimized coordinates partitioning, a structure of
the optimally partitioned vectors is discussed on the basis of a gradient analysis of the separate constraint sub-manifolds
at the configuration and the velocity levels when holonomic and non-holonomic constraints are present in the system. It is
shown that, for holonomic systems, the vectors of optimally partitioned coordinates have the same structure for the generalized
positions and velocities. On the contrary, in the case of non-holonomic systems, the optimally partitioned coordinates generally
differ at the configuration and the velocity levels. The conclusions of the paper are illustrated within the framework of
the presented numerical example. 相似文献
106.
Marin Petrovic Alojz Ivankovic Neal Murphy 《Journal of the European Ceramic Society》2012,32(12):3021-3027
Polycrystalline diamond (PCD) materials are used in various applications, mainly as cutting tools for machining non-ferrous metals and non-metallic materials and for rock drilling operations. A better knowledge of their mechanical properties is of fundamental importance to PCD manufacturers and end users. In order to understand and predict the behaviour and structural integrity of the tools containing PCD, it is first necessary to study the behaviour of the material as a function of loading rate and temperature.In this paper, material behaviour is determined under testing conditions which correspond more closely to those in actual drilling, which is a significant improvement over investigations to date. Young's modulus determined by four-point bending and a split-Hopkinson pressure bar apparatus was relatively constant with the rate, while a consistent decrease was observed with increase of temperature. The flexural strength was found to increase with the temperature, while decreasing with an increase in rate. 相似文献
107.
Jasna Hrenovic Tomislav Ivankovic Mirela Rozic 《Journal of Bioscience and Bioengineering》2010,110(2):180-186
The goal of this study was to determine the concentrations of Mg, Ca and K ions required for the formation of metabolically active population of phosphate (P)-accumulating bacterium Acinetobacter junii. The availability of Mg, Ca and K originating from natural minerals in the conditions of severe shortage of these cations was tested. In the case of shortage of Mg, Ca and K ions in wastewater the P removal was absent due to the decay of A. junii. In the cases of Mg or K shortage in wastewater the P removal was negligible due to the decay of A. junii, while Ca was not essential for the examined bacterium. The minimal required concentrations of Mg and K in synthetic wastewater were 0.64 mg Mg/mg P and 0.50 mg K/mg P. The natural zeolitized tuffs and bentonite, either in Mg, Ca or K form, successfully replaced the lack of Mg, Ca, K and trace metals in wastewater. The requirement of A. junii for examined cations was in the order: Mg > K > Ca. 相似文献
108.
Hella Tokos Zorka Novak Pintarič Yongrong Yang Zdravko Kravanja 《American Institute of Chemical Engineers》2012,58(3):884-898
This article presents an approach to designing a large‐scale water system, which integrates water‐using operations and wastewater treatment units in different production sections within the same network. This approach uses a mixed‐integer nonlinear programming (MINLP) model for water reuse and regeneration reuse in batch and semicontinuous processes. The application of this mathematical formulation to large‐scale industrial problems with changing daily production schedule leads to huge and complex mathematical models. Two alternative multilevel strategies are proposed to solve such problems by means of temporal decomposition. The approach is illustrated with a brewery case study that integrates water consumers in two production sections. The results obtained show that, despite the high piping cost, integration of both sections yields better result than the separate water network design in each section. © 2011 American Institute of Chemical Engineers AIChE J, 2012 相似文献
109.
During numerical forward dynamics of constrained multibody systems, a numerical violation of system kinematical constraints
is the important issue that has to be properly treated. In this paper, the stabilized time-integration procedure, whose constraint
stabilization step is based on the projection of integration results to underlying constraint manifold via post-integration
correction of the selected coordinates is discussed. A selection of the coordinates is based on the optimization algorithm
for coordinates partitioning. After discussing geometric background of the optimization algorithm, new formulae for optimized
partitioning of the generalized coordinates are derived. Beside in the framework of the proposed stabilization algorithm,
the new formulae can be used for other integration applications where coordinates partitioning is needed. Holonomic and non-holonomic
systems are analyzed and optimal partitioning at the position and velocity level are considered further. By comparing the
proposed stabilization method to other projective algorithms reported in the literature, the geometric and stabilization issues
of the method are addressed. A numerical example that illustrates application of the method to constraint violation stabilization
of non-holonomic multibody system is reported.
An erratum to this article can be found at 相似文献
110.
Multimodal interfaces incorporating embodied conversational agents enable the development of novel concepts with regard to interaction management tactics in responsive human–machine interfaces. Such interfaces provide several additional nonverbal communication channels, such as natural visualized speech, facial expression, and different body motions. In order to simulate reactive humanlike communicative behavior and attitude, the realization of motion relies on different behavioral analyses and realization tactics and approaches. This article proposes a novel environment for “online” visual modeling of humanlike communicative behavior, named EVA-framework. In this study we focus on visual speech and nonverbal behavior synthesis by using hierarchical XML-based behavioral events and expressively adjustable motion templates. The main goal of the presented abstract motion notation scheme, named EVA-Script, is to enable the synthesis of unique and responsive behavior. 相似文献