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排序方式: 共有144条查询结果,搜索用时 31 毫秒
1.
Powertrain hybridization as well as electrical energy management are imposing new requirements on electrical storage systems in vehicles. This paper characterizes the associated vehicle attributes and, in particular, the various levels of hybrids. New requirements for the electrical storage system are derived, including: shallow-cycle life, high dynamic charge acceptance particularly for regenerative braking and robust service life in sustained partial-state-of-charge usage. Lead/acid, either with liquid or absorptive glass-fibre mat electrolyte, is expected to remain the predominant battery technology for 14 V systems, including micro-hybrids, and with a cost-effective battery monitoring system for demanding applications. Advanced AGM batteries may be considered for mild or even medium hybrids once they have proven robustness under real-world conditions, particularly with respect to cycle life at partial-states-of-charge and dynamic charge acceptance. For the foreseeable future, NiMH and Li-ion are the dominating current and potential battery technologies for higher-functionality HEVs. Li-ion, currently at development and demonstration stages, offers attractive opportunities for improvements in performance and cost. Supercapacitors may be considered for pulse power applications. Aside from cell technologies, attention to the issue of system integration of the battery into the powertrain and vehicle is growing. Opportunities and challenges for potential “battery pack” system suppliers are discussed. 相似文献
2.
Cornelius Temmel Nils-Gunnar Ingesten Birger Karlsson 《Metallurgical and Materials Transactions A》2006,37(10):2995-3007
Anisotropy of forged steel components is especially adverse when it concerns rotationally symmetric components. Manganese
sulfides (MnS) in steels may be desired for their improvement of machining properties; however, they also deteriorate fatigue
behavior. A quantification of the effect of MnS on anisotropy is necessary to find an optimum for component dimensioning.
To isolate the influence of MnS on anisotropy only, high cleanness of the test material is required. The test material in
the current investigation was molten in a vacuum furnace to high-cleanness composition. Materials with two different S levels
were produced to detect variations in anisotropy according to amount, shape, and distribution of the MnS inclusions. The two
batches were cross-rolled to plates with a deformation ratio of 4.5. The MnS phase constitutes, upon forging or rolling, pancake-shaped
inclusions. In the case of cross-rolling, an in-plane rotational symmetry of the inclusions could be created. The shape and
size of these inclusions are essential for the mechanical behavior of the material. Push-pull fatigue testing was performed
in longitudinal (in plane) and short transversal directions relative to the rolling plane. The results showed strong anisotropy
of the fatigue behavior with inferior performance in short transverse directions where the principal stress is perpendicular
to the flattened inclusions. The anisotropy was somewhat more pronounced for the high-S material, resulting from a different
fatigue crack growth mechanism. 相似文献
3.
Jansson Birger; Palmcrantz Carolina; Uhlen Mathias; Nilsson Bjorn 《Protein engineering, design & selection : PEDS》1990,3(6):555-561
A novel gene fusion system to express and purify small recombinantproteins in Escherichia coli has been constructed. The conceptallows for affinity purification of soluble gene products bysequential albumin- and Zn2+-affinity chromatography. The dual-affinitysystem is well suited for expression of unstable proteins asonly full-length protein is obtained after purification andproteins gain proteolytic stability in the fusion protein. Herewe show that the dual-affinity approach can be used for theexpression of various unstable derivatives of a single IgG-bindingdomain based on staphylococcal protein A. Analysis of the proteolyticstabilities and the IgG-binding properties of the differentmutant proteins suggest that the model for the structure ofan IgG-binding domain must be re-evaluated. 相似文献
4.
We present the AMGA metadata catalogue, which was developed as part of the EGEE (enabling Grids for EsciencE) project’s gLite
Grid middleware. AMGA provides access to meta data for files stored on the Grid, as well as a simplified general access to
relational data stored in database systems. Design and implementation of AMGA was done in close collaboration with the very
diverse EGEE user community to make sure all functionality, performance and security requirements were met. In particular,
AMGA targets the needs of the high energy physics community to rapidly access very large amounts of metadata, as well as the
needs for security of the biomedical community. AMGA therefore tightly integrates fine grained access control making use of
a virtual organisation management system. In addition, it offers advanced federation and features to increase dependability,
performance and data security. 相似文献
5.
Johan Montagnat Ákos Frohner Daniel Jouvenot Christophe Pera Peter Kunszt Birger Koblitz Nuno Santos Charles Loomis Romain Texier Diane Lingrand Patrick Guio Ricardo Brito Da Rocha Antonio Sobreira de Almeida Zoltán Farkas 《Journal of Grid Computing》2008,6(1):45-59
The medical community is producing and manipulating a tremendous volume of digital data for which computerized archiving,
processing and analysis is needed. Grid infrastructures are promising for dealing with challenges arising in computerized
medicine but the manipulation of medical data on such infrastructures faces both the problem of interconnecting medical information
systems to Grid middlewares and of preserving patients’ privacy in a wide and distributed multi-user system. These constraints
are often limiting the use of Grids for manipulating sensitive medical data. This paper describes our design of a medical
data management system taking advantage of the advanced gLite data management services, developed in the context of the EGEE
project, to fulfill the stringent needs of the medical community. It ensures medical data protection through strict data access
control, anonymization and encryption. The multi-level access control provides the flexibility needed for implementing complex
medical use-cases. Data anonymization prevents the exposure of most sensitive data to unauthorized users, and data encryption
guarantees data protection even when it is stored at remote sites. Moreover, the developed prototype provides a Grid storage
resource manager (SRM) interface to standard medical DICOM servers thereby enabling transparent access to medical data without
interfering with medical practice. 相似文献
6.
This consolidation of unidirectional APC-2 was studied experimentally to determine the effects of processing parameters (pressure, temperature, and number of layers) on resin flow as measured by the Kozeny constant and the bulk modulus. The Kozeny constant obtained was between 0.0205 and 0.107. It was found to depend on the consolidation pressure, temperature, number of layers, and their interactions at a 99% confidence level. The value of the bulk modulus was found to be between 1.21 MPa (175 psi) and 8.58 MPa (1244 psi). It also was found to depend on the temperature, pressure, number of plies, and their interactions at a 99% confidence level. These results show the critical effects of fiber orientation on resin flow during processing. 相似文献
7.
The partially purified lipase from Rhizopus sp was tested as a biocatalyst for the synthesis of monolaurin from lauric acid and glycerol. A central composite rotatable design was applied to optimize the substrate molar ratio and the percentage of molecular sieve for achieving maximum monolaurin yield. The best results were obtained when the molar ratio of substrates was 1:1, the medium contained 100% (w/w) molecular sieve, and the reaction was conducted at 50 °C and 200 rpm applying 2 mg of the partially purified lipase. The maximum yield in monolaurin (17.52%) was achieved after a 72‐h reaction. 相似文献
8.
Jose Manuel Román Marín Henrik Koblitz Rasmussen Ole Hassager 《Nanoscale research letters》2010,5(2):274-278
A proof of concept study of the feasibility of fully three-dimensional (3D) time-dependent simulation of nano-imprint lithography
of polymer melt, where the polymer is treated as a structured liquid, has been presented. Considering the flow physics of
the polymer as a structured liquid, we have followed the line initiated by de Gennes, using a Molecular Stress Function model
of the Doi and Edwards type. We have used a 3D Lagrangian Galerkin finite element methods implemented on a parallel computer
architecture. In a Lagrangian techniques, the node point follows the particle movement, allowing for the movement of free
surfaces or interfaces. We have extended the method to handle the dynamic movement of the contact line between the polymer
melt and stamp during mold filling. 相似文献
9.
Ove Wolfgang Arne Haugstad Birger Mo Anders Gjelsvik Ivar Wangensteen Gerard Doorman 《Energy》2009,34(10):1642
The Norwegian Energy Act that came into force in 1991 deregulated the electricity market and removed the former obligation power companies had to supply electricity to the geographical area they were responsible for. Hence producers can supply electricity on the basis of profitability. In 2007 the Energy Act was evaluated by the Government. As a part of this, a study concerning hydro reservoir handling before and after deregulation was carried out by SINTEF. Public statistics show that average hydro reservoir levels measured in per cent of reservoir capacity have been reduced after 1990. We have used the power-market model EMPS1 (EFI's Multi-area Power-market Simulator) to analyze if this reduction can be explained by natural variation in climatic variables or by structural changes that have occurred after 1990. Simulation results show that the reduced reservoir levels cannot be explained by natural variation in climatic variables. Structural changes such as increased transmission capacities can, however, explain some of the reduction. Our study does not indicate that the present reservoir handling gives reservoir levels that are too low. In this paper we also describe the stochastic dynamic optimization problem for long-term hydropower scheduling, and we explain how this problem actually is solved by the EMPS model. 相似文献
10.
A new citation search strategy is proposed for Information Retrieval (IR) based on the principle of polyrepresentation (Ingwersen, 1992, 1996). The strategy exploits logical overlaps between a range of cognitively different interpretations of the same
documents in a structured manner, i.e. so-called cognitive overlaps of representations. The strategy is essentially a "cycling
strategy" starting with documents retrieved by a subject search, wherefrom new documents are identified automatically by following
the network of citations in scientific papers backwards and forwards in time. In contrast to earlier citation search strategies
the proposed strategy does not require known relevant documents (seed documents) as a starting point, but may be based on
a subject search. A pilot study is reported where the ability of the strategy to retrieve additional relevant documents is
analysed. Results show that a very large amount of documents can be retrieved by the strategy, and that these may be segmented
in a number of distinct "overlap levels". It is demonstrated that the combined core of the higher-level overlaps contains
higher relevance density than found in the original retrieval results. Based on these results it is suggested that the documents
be displayed in order of their presence in higher-level overlaps, so as to maximise the chances that as many relevant documents
as possible will be presented first to a user.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献