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151.
J. Rögner B. Okolo S. Kurzenhäuser M. Müller W. Bauer H.-J. Ritzhaupt-Kleissl E. Kerscher V. Schulze 《Microsystem Technologies》2008,14(12):1831-1837
Due to size effects the mechanical behavior of micro-components with dimensions in the range of some 100 μm and structure
details of about 10 μm differs markedly from those of larger components. This is a crucial aspect for the design of micro-components
for applications where demands for high strength are critical. The present study, which was performed in the frame of the
Collaborative Research Centre 499 (SFB 499), approaches this issue by investigating the relationship between production process,
microstructure and the mechanical properties of micro-specimens made from zirconia using two different feedstocks. The specimens
were produced by a sintering process. The sintering temperature was varied between 1,300 and 1,500°C. Mechanical and tribological
behavior of the specimens was determined by three-point bending tests as well as static and sliding friction tests, respectively.
Properties derived from these tests were then correlated to the surface states in the specimens such as porosity, edge radius
and roughness. The strength of the micro-specimens was found to be significantly influenced by these surface features. Whilst
low porosity alone is not sufficient for high strength, notch effects resulting from pores as well as surface roughness can
lower the strength. With increasing edge radius the strength of the material also increases. The porosity, edge radius and
surface roughness were mathematically correlated with the strength to allow for a forecast. Within the SFB 499 feedstocks
with specific properties were designed and reliable processes were developed to guarantee desirable surface roughness and
porosity in the specimens. A characteristic bending strength of about 2,000 MPa is realizable in the micro-specimens within
a good statistical reliability. The tribological tests revealed that the wear properties of the zirconia micro-components
are strongly dependent on the quality of the feedstock. 相似文献
152.
For “on board” diagnosis purposes of the injected fuel quantity flow sensitive elements based on the thermo-resistive measurement
principle were integrated into finished Common Rail injection nozzles of valve-covered orifice (VCO) or mini-sac hole (MSH)
class. Electron-discharge machining as well as electron beam welding technique are key technologies for a reliable integration
procedure. To demonstrate negligible influence on the hydraulic performance of the nozzle after modification an optical measurement
set-up is used to record temporally resolved the propagation of the spray patterns ejected from the six injection holes simultaneously.
From these investigations the impact on the structural distortion of the valve caused by the welding seam is proved as its
position can be directly linked to any chances in spray performance of each individual injection hole. Reducing the energy
input during the electron beam welding lowers substantially the asymmetry in spray patterns from hole to hole as the needle
uncovers the six injection holes more symmetrically. Besides this important finding, the numerical calculations indicate that
the implementation of the sensor chip slightly amplifies the asymmetry induced by the welding process due to an additional
weakening of the nozzle body which is confirmed experimentally. Despite these challenges, however, it is demonstrated that
appropriate parameters for the integration procedure can be found affecting the hydraulic performance negligible compared
to the original state. 相似文献
153.
Darcy T. Haluzan David M. Klymyshyn Martin Börner Sven Achenbach Garth Wells Timo Mappes Jürgen Mohr 《Microsystem Technologies》2008,14(9-11):1709-1714
High aspect ratio variable capacitors have been fabricated using deep X-ray lithography and electroplating. Stiction phenomena applicable to high aspect ratio devices are presented, including the conditions for stiction to occur and the critical dimensions of structures. Actuation tests at 3 GHz are also presented and show a maximum capacitance of 0.86 pF with no actuation voltage and a minimum capacitance of 0.70 pF with an actuation voltage of 20 V just before pull-in, which gives a tuning range of 1.23:1. Corresponding Q-factor values are 49.3 and 70.8 respectively. After pull-in, the measured capacitance is 0.61 pF, corresponding to a tuning range of 1.41:1, with a maximum Q-factor of 102.9. 相似文献
154.
Sylvain Tourancheau Kjell Brunnström Börje Andrén Patrick Le Callet 《Journal of the Society for Information Display》2009,17(3):239-249
Abstract— The primary goal of this study was to find a measurement method for motion blur which is easy to carry out and gives results that can be reproduced from one lab to another. This method should be able to also take into account methods for reduction of motion blur such as backlight flashing. Two methods have been compared. The first method uses a high‐speed camera that permits us to directly picture the blurred‐edge profile. The second one exploits the mathematical analysis of the motion‐blur formation to construct the blurred‐edge profile from the temporal step response. Measurement results and method proposals are given and discussed. 相似文献
155.
James Alfred Walker Katharina Völk Stephen L. Smith Julian Francis Miller 《Genetic Programming and Evolvable Machines》2009,10(4):417-445
Parallel and distributed methods for evolutionary algorithms have concentrated on maintaining multiple populations of genotypes,
where each genotype in a population encodes a potential solution to the problem. In this paper, we investigate the parallelisation
of the genotype itself into a collection of independent chromosomes which can be evaluated in parallel. We call this multi-chromosomal evolution
(MCE). We test this approach using Cartesian Genetic Programming and apply MCE to a series of digital circuit design problems
to compare the efficacy of MCE with a conventional single chromosome approach (SCE). MCE can be readily used for many digital
circuits because they have multiple outputs. In MCE, an independent chromosome is assigned to each output. When we compare
MCE with SCE we find that MCE allows us to evolve solutions much faster. In addition, in some cases we were able to evolve
solutions with MCE that we unable to with SCE. In a case-study, we investigate how MCE can be applied to to a single objective
problem in the domain of image classification, namely, the classification of breast X-rays for cancer. To apply MCE to this
problem, we identify regions of interest (RoI) from the mammograms, divide the RoI into a collection of sub-images and use
a chromosome to classify each sub-image. This problem allows us to evaluate various evolutionary mutation operators which
can pairwise swap chromosomes either randomly or topographically or reuse chromosomes in place of other chromosomes. 相似文献
156.
Hybrid systems are heterogeneous systems characterised by the interaction of discrete and continuous dynamics. We present a trajectory-based algebraic model for describing hybrid systems; the trajectories used are closely related to streams. The algebra is based on left quantales and left semirings and provides a new application for these algebraic structures. We show that hybrid automata, which are probably the standard tool for describing hybrid systems, can conveniently be embedded into our algebra. Moreover we point out some important advantages of the algebraic approach. In particular, we show how to handle Zeno effects, which are excluded by most other authors. The development of the theory is illustrated by a running example and a larger case study. 相似文献
157.
Recent research of complex networks has significantly contributed to the understanding how networks can be classified according
to its topological characteristics. However, transport networks attracted less attention although their importance to economy
and daily life. In this work the development of the Swiss road and railway network during the years 1950–2000 is investigated.
The main difference between many of the recently studied complex networks and transport networks is the spatial structure.
Therefore, some of the well-established complex network measures may not be applied directly to characterise transport networks
but need to be adapted to fulfil the requirements of spatial networks. Additionally, new approaches to cover basic network
characteristics such as local network densities are applied. The focus of the interest hereby is always not only to classify
the transport network but also to provide the basis for further applications such as vulnerability analysis or network development.
It could be showed that the proposed measures are able to characterise the growth of the Swiss road network. To proof the
use of local density measures to explain the robustness of a network however needs further research.
相似文献
Kay W. AxhausenEmail: |
158.
Christoph Riedl Tilo Böhmann Michael Rosemann Helmut Krcmar 《Information Systems and E-Business Management》2009,7(2):199-221
Service-oriented architectures and Web services mature and have become more widely accepted and used by industry. This growing
adoption increased the demands for new ways of using Web service technology. Users start re-combining and mediating other
providers’ services in ways that have not been anticipated by their original provider. Within organisations and cross-organisational
communities, discoverable services are organised in repositories providing convenient access to adaptable end-to-end business
processes. This idea is captured in the term Service Ecosystem. This paper addresses the question of how quality management
can be performed in such service ecosystems. Service quality management is a key challenge when services are composed of a
dynamic set of heterogeneous sub-services from different service providers. This paper contributes to this important area
by developing a reference model of quality management in service ecosystems. We illustrate the application of the reference
model in an exploratory case study. With this case study, we show how the reference model helps to derive requirements for
the implementation and support of quality management in an exemplary service ecosystem in public administration. 相似文献
159.
Karlsson H Mörtstedt H Lindqvist H Tagesson C Lindahl M 《Proteomics. Clinical applications》2009,3(6):663-671
Although obesity and high levels of low-density lipoprotein (LDL) are well-known risk factors for cardiovascular disease, the precise role(s) of different LDL constituents in obesity has not been explored. In the present study, we compared the LDL proteome of healthy control adults (body mass index<25) and obese subjects (body mass index>30). LDL was isolated by density-gradient ultracentrifugation and proteins were separated with 2-D PAGE, quantified, and identified by peptide mass fingerprinting using MALDI-TOF MS. A new LDL-associated protein was identified as transthyretin and found to be significantly more abundant in LDL from the obese subjects. In addition, LDL from the obese subjects contained relatively more α(1) -antitrypsin, apo J, apo C-II, than LDL from controls, and also more of an acidic isoform (pI/Mr; 5.2/23 100) of apo A-I. On the other hand, the relative amounts of apo A-IV and the major isoform of apo A-I (pI/Mr; 5.3/23 100) were significantly less in LDL from the obese subjects. Apo E was less and non-sialylated apo C-III more abundant in LDL from obese men than control men, while there were no such differences between LDL from obese and control women. These findings illustrate that obesity is not only associated with increased LDL-cholesterol levels but also with alterations in the LDL protein composition. The presence of transthyretin in LDL from obese subjects may reflect over-nutrition and affect the lipid metabolism in obesity. 相似文献
160.