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161.
An efficient hybrid field solution to the general multilayer substrates transmission line problems with full shielded and half open cross-sectional geometry is presented by using the waveguide modes coupling and decoupling procedure in the spectral domain. Modal transverse transmission lines corresponding to the LSE and LSM modes are taken into account so that the Green's elements for the edge conditions can be derived by a simple iterative method. In this paper, we analyze not only the propagation constants and characteristic impedances but also the available transmission power capacity and power distribution of most commonly used structures. Normalized eigenmode power levels characterizing the propagation features are computed. 相似文献
162.
Stéphanie Ricol Etienne Vernaz Philippe Barboux 《Journal of Sol-Gel Science and Technology》1997,8(1-3):229-233
Gels have been synthesized in the SiO2-Na2O-ZrO2 system and calcined at various temperatures up to 700°C. They have been studied by infrared absorption spectroscopy. The position of the asymmetric stretching frequency of the SiO4 unit is used as a tracer of the homogeneity. It is shown that sodium increases the solubility of zirconium in the silica matrix as already observed in fused glasses. 相似文献
163.
光谱实验室的建设和管理 总被引:1,自引:0,他引:1
阐述冶金、铸造等行业用于金属成分分析的直读发射光谱仪实验室的建设和管理。从仪器的调研、选型,实验室选址,基础设施设备的准备,仪器的安装、调试、验收、日常分析,实验室管理等几个方面,分别作了介绍。 相似文献
164.
A laboratory information management system (LIMS) can make a major contribution to the quality and therefore to the efficiency
and competitiveness of a laboratory. Since it can impact all aspects of a laboratory's organization it must be the key if
not the principal player of the laboratory's quality system. It should support the laboratory in establishing, maintaining
and applying quality procedures thereby enabling the laboratory to achieve its quality goals. As a tool, LIMS permits the
laboratory to input and use its own know-how and experience to optimize the total organization (internal and external) and
workflow of generated information. However, perceived "quality" in the context of an LIMS, can be viewed as being made up
of different facets such as the security, reliability and accessibility of information as well as its turn around time and
production cost. This paper reviews the role of a LIMS in the laboratory and the contribution that both system design and
functionality can have on "building quality ".
Received: 5 October 1998 · Accepted: 20 October 1998 相似文献
165.
I.A. Schneider D. Kramer A. Wokaun G.G. Scherer 《Electrochemistry communications》2005,7(12):1393-1397
A method for performing neutron radiography and locally resolved impedance spectroscopy simultaneously in situ in an operating polymer electrolyte fuel cell (PEFC) is presented. The new method provides concurrently spatially resolved information about the local cell performance, the locally limiting processes, and the liquid water distribution. Information about the impact of water on cell performance and limiting processes can be gained in situ on a local scale in an operating PEFC. The method was applied to a PEFC operated on pure H2/O2 in co-flow mode under low humidity operating conditions. The results show that in co-flow mode strong flooding and severe drying can occur at the very same time in different sections of a PEFC. 相似文献
166.
Martin Gruebele 《Theoretical chemistry accounts》2003,109(2):53-63
Vibrational energy flow in organic molecules occurs by a multiple-time-scale mechanism that can be modeled by a single exponential
only in its initial stages. The mechanism is a consequence of the hierarchical structure of the vibrational Hamiltonian, which
leads to diffusion of vibrational wavepackets on a manifold with far fewer than the 3N−6 dimensions of the full vibrational state space. The dynamics are controlled by a local density of states, which does not
keep increasing with molecular size. In addition, the number of vibrational coordinates severely perturbed during chemical
reaction is small, leading to preservation of the hierarchical structure at chemically interesting energies. This regularity
opens up the possibility of controlling chemical reactions by controlling the vibrational energy flow. Computationally, laser
control of intramolecular vibrational energy redistribution can be modeled by quantum-classical, or by purely quantum-mechanical
models of the molecule and control field.
Received: 26 July 2002 / Accepted: 30 September 2002 / Published online: 2 December 2002
Electronic Supplementary Material to this paper can be obtained by using the Springer Link server located at http://dx.doi.org/10.1007/s00214-002-0394-2.
Acknowledgements. This work was supported by NSF grant CHE 9986670.
Correspondence to: M. Gruebele e-mail: gruebele@scs.uiuc.edu 相似文献
167.
Margaret M. Robins S. Jane Scarll Pauline E. Key 《Accreditation and quality assurance》2006,11(5):214-223
During the last decade, it has become increasingly important that researchers demonstrate that research is conducted to the highest standards. The implementation of quality assurance for research laboratories will enable all fields of research and development to be judged impartially. There are no specific standards for research laboratories but where possible, existing standards can be adapted. This review is structured around two approaches. The first considers research to be a logical extension of testing, and it is assumed that testing standards can be applied methodically to each step in a research project. The second advocates a flexible approach, with research-specific criteria for assessing quality. The important papers published on this topic have been reviewed. The conclusions are that the general quality management approach, encompassed by the ISO 9000 series of standards with the emphasis on customer satisfaction and ‘fitness for purpose’, is suitable for implementing quality assurance in research laboratories. 相似文献
168.
Environmental quality is still deteriorating in the EU and worldwide despite all the Directives and Regulations in this field
over the past 20 years. The European Community has devised a new approach to this problem with the introduction of the Eco-Management
and Audit Scheme Regulation. This Regulation provides industry with an opportunity to demonstrate that it can achieve continuous
improvement in its environmental performance through a voluntary scheme which is not based on the traditional command and
control mechanisms of Directives. This paper gives an overview of the steps involved in implementing the European Eco-Management
and Audit Scheme and the role of accreditation in supporting the scheme. 相似文献
169.
Given n samples(viewed as an n-tuple) of a γ-regular discrete distribution π,in this article the authors concern with the weighted and unweighted graphs induced by the n samples. They first prove a series of SLLN results(of Dvoretzky-Erd¨os’ type). Then they show that the vertex weights of the graphs under investigation obey asymptotically power law distributions with exponent 1 + γ. They also give a conjecture that the degrees of unweighted graphs would exhibit asymptotically power law distribu... 相似文献
170.