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排序方式: 共有515条查询结果,搜索用时 343 毫秒
61.
An interesting universal modeling tool for rechargeable lithium batteries is presented in this paper. The generic model is based on an equivalent circuit technique commonly used in electrochemical impedance characterization. Therefore, the parameters used in the model can be easily parameterized from the electrochemical impedance derivations, which provide a convenient integration with experimental cell characterizations. Such integration offers the universality in this modeling approach. 相似文献
62.
Pierre Brun Jean-Franois Glicenstein Emmanuel Moulin Matthieu Vivier For the H.E.S.S. Collaboration 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,630(1):291
WIMP annihilations are required to reproduce the correct dark matter abundance in the Universe. This process can occur in dense regions of our Galaxy such as the Galactic center, dwarf galaxies and other types of sub-haloes. High-energy γ-rays are produced in dark matter particle collisions and can be detected by Cherenkov telescopes such as H.E.S.S. We report here the search for γ-ray signals from the Galactic center and the nearby Sagittarius and Canis Major satellites. In the absence of a convincing signal, modelling the dark matter density within these objects allows to put constraints on the WIMP parameters such as its mass and annihilation cross-section. Beyond these targeted searches, the wide-field survey of the inner Galaxy with H.E.S.S. is used to constrain sub-halo formation models involving intermediate-mass black holes. 相似文献
63.
The state of Nevada has extensive mineral resources, and is the largest producer of gold in the USA as well as fourth in world gold production. Mercury (Hg) is often present in the hydrothermal systems that produce gold deposits, and can be found in elevated concentrations in gold ore. As a result, mining of gold ore in Nevada has been shown to release Hg to the atmosphere from point and non-point sources. This project focused on measurement of air-soil Hg exchange associated with undisturbed soils and bedrock outcrops in the vicinity of two large gold mines. Field and laboratory data collected were used to identify the important variables controlling Hg flux from these surfaces, and to estimate a net flux from the areas adjacent to the active mines as well as that occurring from the mined area pre-disturbance. Mean daily flux by substrate type ranged from 9 ng m− 2 day− 1 to 140 ng m− 2 day− 1. Periods of net deposition of elemental Hg were observed when air masses originating from a mine site moved over sampling locations. Based on these observations and measured soil Hg concentrations we suggest that emissions from point and non-point sources at the mines are a source of Hg to the surrounding substrates with the amount deposited not being of an environmental concern but of interest mainly with respect to the cycling of atmospheric elemental Hg. Observations indicate that while some component of the deposited Hg is sequestered in the soil, this Hg is gradually released back to the atmosphere over time. Estimated pre-disturbance emissions from the current mine footprints based on field data were 0.1 and 1.7 kg yr− 1, compared to that estimated for the current non-point mining sources of 19 and 109 kg yr− 1, respectively. 相似文献
64.
描述了TI公司媒体处理器TMS320DM642HPI的主要特点,介绍了PCI桥接器PCI2040的结构原理,提出了通过PCI2040实现TMS320DM642与PC/104+模块进行通信的设计方案。本方案充分利用PCI总线的高数据吞吐能力和DSP的HPI接口功能,可在DSP和PC/104+模块之间实现较高的数据传输率,实现了PC/104+实时读/写DSP任意片内存储单元的内容。最后给出交通视频监控系统的设计方案,详细说明了通信过程的软件编程。 相似文献
65.
XF Yang PE Milhiet F Gaudoux P Crine G Boileau 《Canadian Metallurgical Quarterly》1993,71(5-6):278-287
We have isolated and sequenced a full-length cDNA for rabbit kidney aminopeptidase N (APN). The 3-kilobase cDNA contains 12 nucleotides of the 5' noncoding region, a 2898 nucleotide long open reading frame, and 113 nucleotides of the 3' untranslated region. The open reading frame encodes a type II membrane protein of 966 amino acid residues composed of a 10 residue NH2-terminal cytosolic domain, a 23 residue transmembrane domain, and a large 933 residue ectodomain that contains the active site. Rabbit APN has eight potential N-glycosylation sites and seven cysteine residues, one of which is located in the transmembrane domain. Computer analysis showed that the enzymes from human, rat, and rabbit were highly conserved, except for the stalk region immediately downstream from the transmembrane domain. Using in situ hybridization techniques we showed that in rabbit kidney, APN mRNA is present in proximal tubules but not in glomeruli, which corresponds to the localization of the protein observed by immunohistochemistry. Taken together, our results strongly suggest that the expression of APN in kidney is modulated at mRNA levels and not at translational and (or) posttranslational levels. 相似文献
66.
67.
This article describes a new approach to improve the analysis of the chemical modifications that result from the degradation of polymers under UV-visible light exposure in the presence of oxygen. The tool which is used consists of an irradiation chamber whose atmosphere is composed of 18O2. The 18O2 pressure inside the chamber and the hygrometry can be adjusted. In this study, particular attention was paid to the photo-oxidation of poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV). Using infrared spectroscopy, irradiation under the oxygen 18 atmosphere allowed discrimination between compounds formed via fixation of oxygen from the atmosphere and those formed by reorganisation of the matrix. In addition, irradiation of MDMO-PPV in an 18O2 wet atmosphere allowed for detection of the presence of phenyl formate and aromatic ketone functions. This permitted validating the mechanism of photo-oxidation previously proposed. Additionally, with regard to blends made with MDMO-PPV and methano-fullerene[6,6]-phenyl C61-butyric acid methyl ester ([60] PCBM), it was demonstrated that this technique facilitates the identification of the photo-oxidation products formed. 相似文献
68.
p-Cycle protection is a fairly new survivability scheme that has the interesting properties of offering restoration speeds essentially the same as those offered by ring protection while requiring almost as little redundant capacity as adaptive mesh restoration [D. Stamatelakis, W.D. Grover, IEEE Transactions on Communications, vol. 48, no. 8, (August 2000), pp. 1262–1265]. This paper presents the first analytical consideration of the availability of paths in a network protected by p-cycles. Results confirm the importance that cycle sizes play in terms of availability and suggests principles or strategies for achieving high availability of paths in a network protected by p-cycles. Based on these insights, two new formulations for joint service path provisioning and capacity planning are proposed. The first one offers a way to improve the availability of selected service paths by using a different routing strategy for them than for regular service paths. The second formulation enables a new class of service paths that are offered two protection options instead of just one. That class of service paths is expected to see its availability improved in a quantum step way relative to the availability of paths having only one protection option. 相似文献
69.
Span-Restorable Mesh Networks with Multiple Quality of Protection (QoP) Service Classes 总被引:1,自引:0,他引:1
In the modern business environment there is considerable interest in being able to support a range of different transport service classes in an optical network, and charge accordingly. In this work we consider the capacity design problem for a mesh-restorable optical network supporting any mixture of four basic quality of protection (QoP) classes. The service definitions are (gold): assured restorability, (silver): best efforts, (bronze): non-protected and (economy): preemptible service. We give design models for optimal capacity design of span-restorable (or corresponding link-protected) mesh networks having any particular mixture of these service classes. We also apply and test the design models under several multi-QoP test case scenarios to gain insights about various strategies and options possible in a multi-QoP design environment. An interesting finding is that in some test cases, 15 to 30% of all demand can be in the gold class enjoying 100% restorability solely through preemption of economy class service capacity. This suggests the potential to design and operate mesh-based networks that have no spare capacity at all in the conventional sense: all capacity is bearing service of some paying type. The resulting frequency of preemption in the economy class services is also studied. Results also show typically high levels of best-efforts restorability in the silver class occurring in networks that are strictly designed only for the restorability of the gold class services. High restorability of best effort services, however, requires the preemption of economy services. These methods and findings can be used by network and business planners to evaluate a number of different service structuring, pricing, and capacity-design strategies that may offer advantages to them and new options for their customers. 相似文献
70.
Martin MJ Benyattou T Orobtchouk R Rooms F Morand A Schanen I Benech P 《Applied optics》2005,44(13):2558-2563
We report the scanning near-field optical microscopy (SNOM) characterization of a 4 x 4 multimode interference (MMI) device working at a wavelength of 1.55 microm and designed for astronomical signal recombination. A comprehensive analysis of the mapped propagating field is presented. We compare SNOM measurements with beam-propagation-method simulations and thus are able to determine the MMI structure's refractive-index contrast and show that the measured value is higher than the expected value. Further investigation allows us to demonstrate that good care must be taken with the refractive-index profile used in simulation when one deals with low-index contrast structures. We show evidence that a step-index contrast is not suitable for adequate simulation of our structure and present a model that permits good agreement between measured and simulated propagating fields. 相似文献