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81.
This paper presents F-MPJ (Fast MPJ), a scalable and efficient Message-Passing in Java (MPJ) communication middleware for
parallel computing. The increasing interest in Java as the programming language of the multi-core era demands scalable performance
on hybrid architectures (with both shared and distributed memory spaces). However, current Java communication middleware lacks
efficient communication support. F-MPJ boosts this situation by: (1) providing efficient non-blocking communication, which
allows communication overlapping and thus scalable performance; (2) taking advantage of shared memory systems and high-performance
networks through the use of our high-performance Java sockets implementation (named JFS, Java Fast Sockets); (3) avoiding
the use of communication buffers; and (4) optimizing MPJ collective primitives. Thus, F-MPJ significantly improves the scalability
of current MPJ implementations. A performance evaluation on an InfiniBand multi-core cluster has shown that F-MPJ communication
primitives outperform representative MPJ libraries up to 60 times. Furthermore, the use of F-MPJ in communication-intensive
MPJ codes has increased their performance up to seven times. 相似文献
82.
Economic lot-scheduling problem (ELSP) has been studied since the 1950??s. ELSP deals with the scheduling of the production of several items on a single facility in a cyclical pattern. The facility can only produce one single item at a time, and there is a set-up cost and set-up time associated with each item. Because of the rapid development of many emerging markets nowadays, many common items are produced in different places in order to satisfy the demands in different markets. This becomes the multi-facilities ELSP problems. In ELSP problems, it is known that if more items types to be produced by the facility, the production frequency of each item type will increase because of the balancing of the production rate and the demand rate. Consequently, the number of set-up time and set-up cost increases accordingly. Thus, reallocating the common items, which can be produced in any facilities, to be produced only on certain facility can certainly reduce the number of production frequency, and lead to lower related costs. The objective of this paper is to propose an optimization methodology combining Integer Programming and Genetic Algorithm to solve multi-facility ELSP problems. This paper proposes to divide the main problem into a master problem and sub-problems, which are solved by Integer Programming and Genetic Algorithm respectively. To demonstrate the significance of reallocating the common items and aggregating them to produce in certain facility, several models have been designed and tested. The comparison of the models demonstrates the reduction of the costs benefited by result of common items reallocation. 相似文献
83.
84.
The problem of determining the trajectories to control greenhouse crop growth has traditionally been solved by using constrained optimization or applying artificial intelligence techniques. The economic profit has been used as the main criterion in most research on optimization to obtain adequate climatic control setpoints for the crop growth. This paper addresses the problem of greenhouse crop growth through a hierarchical control architecture governed by a high-level multiobjective optimization approach, where the solution to this problem is to find reference trajectories for diurnal and nocturnal temperatures (climate-related setpoints) and electrical conductivity (fertirrigation-related setpoints). The objectives are to maximize profit, fruit quality, and water-use efficiency, these being currently fostered by international rules. Illustrative results selected from those obtained in an industrial greenhouse during the last eight years are shown and described. 相似文献
85.
Ram Jiwari 《Computer Physics Communications》2012,183(11):2413-2423
In this paper, an efficient numerical scheme based on uniform Haar wavelets and the quasilinearization process is proposed for the numerical simulation of time dependent nonlinear Burgers’ equation. The equation has great importance in many physical problems such as fluid dynamics, turbulence, sound waves in a viscous medium etc. The Haar wavelet basis permits to enlarge the class of functions used so far in the collocation framework. More accurate solutions are obtained by wavelet decomposition in the form of a multi-resolution analysis of the function which represents a solution of boundary value problems. The accuracy of the proposed method is demonstrated by three test problems. The numerical results are compared with existing numerical solutions found in the literature. The use of the uniform Haar wavelet is found to be accurate, simple, fast, flexible, convenient and has small computation costs. 相似文献
86.
P. Ramírez de la Piscina J. L. G. Fierro G. Muller J. Sales N. Homs 《Catalysis Letters》1992,14(1):45-49
New heterogenized Pt/Sn catalysts selective for the hydroformylation of 1-pentene have been synthesized. The complex cis-[PtCl2(PPh3)2] and the SnCl2.2H2O or SnC2O4 precursors have been anchored on silica-, magnesia- and alumina-carriers. X-ray photoelectron spectroscopy was used to determine the surface composition and the nature of the anchored species. The hydroformylation activity was found to depend on the type of support and tin precursor used. Only the silica supported catalysts were active in the hydroformylation reaction. Samples prepared from SnCl2-2H2O were 200-fold more active than those prepared from SnC2O4. Selectivity ton-hexanal of the silica-supported catalyst prepared from SnCl2-2H2O was as high as 94.4% at 39.2% conversion of 1-pentene. 相似文献
87.
88.
Network Discovery and Verification 总被引:1,自引:0,他引:1
Beerliova Z. Eberhard F. Erlebach T. Hall A. Hoffmann M. Mihal'ak M. Ram L. S. 《Selected Areas in Communications, IEEE Journal on》2006,24(12):2168-2181
Due to its fast, dynamic, and distributed growth process, it is hard to obtain an accurate map of the Internet. In many cases, such a map-representing the structure of the Internet as a graph with nodes and links-is a prerequisite when investigating properties of the Internet. A common way to obtain such maps is to make certain local measurements at a small subset of the nodes, and then to combine these in order to "discover" (an approximation of) the actual graph. Each of these measurements is potentially quite costly. It is thus a natural objective to minimize the number of measurements which still discover the whole graph. We formalize this problem as a combinatorial optimization problem and consider it for two different models characterized by different types of measurements. We give several upper and lower bounds on the competitive ratio (for the online network discovery problem) and the approximation ratio (for the offline network verification problem) in both models. Furthermore, for one of the two models, we compare four simple greedy strategies in an experimental analysis 相似文献
89.
Peter S. P. Wong Sai On Cheung Peter K. M. Ho 《Canadian Metallurgical Quarterly》2005,131(10):1045-1053
Partnering has been advocated for use in construction as a project-delivery approach to curb dispute and enable a cooperative contracting environment. Successful construction partnering is perceived to derive benefits to both developers and contractors. In view of significant implications to successful project delivery, there has been a surge of research and studies on construction partnering. These studies typically focus on the partnering process as well as the identification of critical success factors. Among the various success factors that underpin partnering success, establishing trust among partners is considered the most important. Moreover, skeptics have been swift to point out that establishing trust in construction is daunting. A better understanding of the role of trust and its manifestation in partnering efforts is therefore of both academic and practical value. In this study, motivating trust in construction partnering is described within the classic framework of “the prisoner’s dilemma,” which suggests the trust cycle can be kick-started if construction partners put cooperation before competition and self-interest. This paper reports a study that is designed to suggest a suitable candidate for the trust initiator. As such, the critical trust factors for two groups of construction partners in Hong Kong—developers/consultants and contractors—are first identified. It is found that “performance” and “permeability” of partners are the two most critical trust factors. “Performance” describes the partner’s competence and problem-solving ability as perceived by their counterpart. “Permeability” reflects the partner’s openness in sharing information. The result of a multiple-regression analysis further suggests that the contractor is in a position to initiate trust through competent performance and maintaining effective communication with the client. In this manner, the trust cycle can expand with reciprocal trustworthiness from the client. 相似文献
90.
Frost Ram; Kugler Tamar; Deutsch Avital; Forster Kenneth I. 《Canadian Metallurgical Quarterly》2005,31(6):1293
Most models of visual word recognition in alphabetic orthographies assume that words are lexically organized according to orthographic similarity. Support for this is provided by form-priming experiments that demonstrate robust facilitation when primes and targets share similar sequences of letters. The authors examined form-orthographic priming effects in Hebrew, Arabic, and English. Hebrew and Arabic have an alphabetic writing system but a Semitic morphological structure. Hebrew morphemic units are composed of noncontiguous phonemic (and letter) sequences in a given word. Results demonstrate that form-priming effects in Hebrew or Arabic are unreliable, whereas morphological priming effects with minimal letter overlap are robust. Hebrew bilingual subjects, by contrast, showed robust form-priming effects with English material, suggesting that Semitic words are lexically organized by morphological rather than orthographic principles. The authors conclude that morphology can constrain lexical organization even in alphabetic orthographies and that visual processing of words is first determined by morphological characteristics. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献