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71.
Andreas Ruh Adam-Mwanga Dieckmann Richard Heldele Volker Piotter Robert Ruprecht Christian Munzinger Jürgen Fleischer Jürgen Haußelt 《Microsystem Technologies》2008,14(12):1805-1811
In the field of micro-technology the production of metallic and ceramic micro-components by powder injection molding (PIM)
has become a more and more established fabrication method. But in order to fulfill the demand for more complex-shaped high-precision
micro-components further development work has to be performed. This is especially true if more efficient production routes
for multi-component-micro-assemblies consisting of different materials or sub-components are envisaged. To meet these challenges,
investigations are performed to realize and to establish two primary shape micro-processes. These are two-component micro-injection
molding (2C-MicroPIM) and sinter-joining. The realization of these technologies will lead to a markedly reduction of the efforts
for handling, adjustment, and assembling of metallic and ceramic micro-assemblies. Furthermore, an increased integration level
and functionality can be yielded. For an effective transfer of scientific results to industrial applications the whole process
chain must be considered, from development and construction of the tooling as well as of the components to the quality assurance
and determination of the properties of the assemblies after sintering. These primary shape processes shall enable the mutual
processing of different materials within the fabrication process, so avoiding separate mounting or assembling steps. Additionally
fixed and loose junctions between at least two components shall be realized. The progress in research and development will
be demonstrated especially by the implementation of shaft-to-collar connections between micro-gearwheels and corresponding
shafts. Regarding two-component micro-injection molding, the tool construction for shaft-to-collar connections will be presented
as well as first experimental results on the properties of selected ceramic powders and feedstocks for the special requirements
of the 2C-MicroPIM process. With the assembly step being performed outside the injection molding tool before sinter-joining
different parts and geometries can be combined quite easily. The presented article gives an overview on the concept and on
preliminary testing results for the fabrication of a shaft-to-collar-connection. Additionally, a solution for an automated
assembly of a shaft and a toothed wheel outside the injection molding tool is presented. 相似文献
72.
The authors reassert the need for methodological changes in depression research appearing in the Journal of Personality and Social Psychology and other personality and social psychology journals. In this rejoinder the authors update their earlier literature review (H. Tennen, J. Hall, & G. Affleck; see record 1995-31710-001) and respond to the commentaries by P C. Kendall and E. C. Flannery-Schroeder (see record 1995-31700-001) and G. Weary, J. A. Edwards, and J. A. Jacobson (see record 1995-31713-001). The authors notice that G. Weary et al.'s own findings demonstrate the need to change how depression is measured and participants are assigned to experimental groups. The authors also challenge G. Weary et al.'s contention that structured interviews are limited because they require interviewer judgments, and they urge personality and social psychologists to learn more about these interviews. Finally, G. Weary et al.'s suspicion that depression research guidelines reflect professional parochialism is disputed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
73.
Level‐set topology optimization with many linear buckling constraints using an efficient and robust eigensolver 下载免费PDF全文
Peter D. Dunning Evgueni Ovtchinnikov Jennifer Scott H. Alicia Kim 《International journal for numerical methods in engineering》2016,107(12):1029-1053
Linear buckling constraints are important in structural topology optimization for obtaining designs that can support the required loads without failure. During the optimization process, the critical buckling eigenmode can change; this poses a challenge to gradient‐based optimization and can require the computation of a large number of linear buckling eigenmodes. This is potentially both computationally difficult to achieve and prohibitively expensive. In this paper, we motivate the need for a large number of linear buckling modes and show how several features of the block Jacobi conjugate gradient (BJCG) eigenvalue method, including optimal shift estimates, the reuse of eigenvectors, adaptive eigenvector tolerances and multiple shifts, can be used to efficiently and robustly compute a large number of buckling eigenmodes. This paper also introduces linear buckling constraints for level‐set topology optimization. In our approach, the velocity function is defined as a weighted sum of the shape sensitivities for the objective and constraint functions. The weights are found by solving an optimization sub‐problem to reduce the mass while maintaining feasibility of the buckling constraints. The effectiveness of this approach in combination with the BJCG method is demonstrated using a 3D optimization problem. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
74.
Jennifer D Key Padmapani Seneviratne 《Applicable Algebra in Engineering, Communication and Computing》2016,27(5):399-412
We show how to find s-PD-sets of the minimal size \(s+1\) for the \(\left[ \frac{q^n-q^u}{q-1},n,q^{n-1}-q^{u-1}\right] _q \) MacDonald q-ary codes \(C_{n,u}(q)\) where \(n \ge 3\) and \(1 \le u \le n-1\). The construction of [6] can be used and gives s-PD-sets for s up to the bound \(\lfloor \frac{q^{n-u}-1}{(n-u)(q-1)} \rfloor -1\), of effective use for u small; for \(u \ge \lfloor \frac{n}{2} \rfloor \) an alternative construction is given that applies up to a bound that depends on the maximum size of a set of vectors in \(V_u(\mathbb {F}_q)\) with each pair of vectors distance at least 3 apart. 相似文献
75.
Quinn Paul C.; Cummins Maggie; Kase Jennifer; Martin Erin; Weissman Sheri 《Canadian Metallurgical Quarterly》1996,32(5):942
A series of experiments examined the abilities of infants to form categorical representations for the spatial relations above and below. Exp 1 provided evidence that 3–4 mo olds can form categorical representations for above and below when a diamond shape was presented above or below a horizontal bar. Exps 2 and 3 showed that 3- and 4-mo olds did not form categorical representations for above and below when a number of discriminably different shapes (e.g., a diamond, a triangle, a dot) appeared above or below the bar. These more abstract categorical representations for above and below were formed by 6- to 7-mo olds (Exp 4). The findings suggest an experientially or maturationally based trend, from concrete to abstract, in the categorical representation of common spatial relations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
76.
Verb Phrase Ellipsis (VPE) has been studied in great depth in theoretical linguistics, but empirical studies of VPE are rare.
We extend the few previous corpus studies with an annotated corpus of VPE in all 25 sections of the Wall Street Journal corpus
(WSJ) distributed with the Penn Treebank. We annotated the raw files using a stand-off annotation scheme that codes the auxiliary
verb triggering the elided verb phrase, the start and end of the antecedent, the syntactic type of antecedent (VP, TV, NP,
PP or AP), and the type of syntactic pattern between the source and target clauses of the VPE and its antecedent. We found
487 instances of VPE (including predicative ellipsis, antecedent-contained deletion, comparative constructions, and pseudo-gapping)
plus 67 cases of related phenomena such as do so anaphora. Inter-annotator agreement was high, with a 0.97 average F-score for three annotators for one section of the WSJ.
Our annotation is theory neutral, and has better coverage than earlier efforts that relied on automatic methods, e.g. simply
searching the parsed version of the Penn Treebank for empty VP’s achieves a high precision (0.95) but low recall (0.58) when
compared with our manual annotation. The distribution of VPE source–target patterns deviates highly from the standard examples
found in the theoretical linguistics literature on VPE, once more underlining the value of corpus studies. The resulting corpus
will be useful for studying VPE phenomena as well as for evaluating natural language processing systems equipped with ellipsis
resolution algorithms, and we propose evaluation measures for VPE detection and VPE antecedent selection. The stand-off annotation
is freely available for research purposes. 相似文献
77.
Carpenters and other construction workers who install drywall have high rates of strains and sprains to the low back and shoulder. Drywall is heavy and awkward to handle resulting in increased risk of injury. The purpose of this study was to evaluate several low-cost coupling tools that have the potential to reduce awkward postures in drywall installers. Five coupling tools were evaluated using the Lumbar Motion Monitor that measures trunk kinematics and predicts probability of low back disorder group membership risk (LBD risk). Workers answered surveys about their comfort while using each tool. The results indicate that use of the 2-person manual lift and the J-handle provide the best reduction in awkward postures, motions, low back sagittal moment, and LBD risk. The two-person manual lift appears to be the safest method of lifting and moving drywall, though using the two-person J-handle also significantly reduces injury risk. Given that carpenters are skeptical about using equipment that can get in the way or get lost, a practical recommendation is promotion of two-person manual lifting. For single-person lifts, the Old Man tool is a viable option to decrease risk of MSDs. 相似文献
78.
Box–Jenkins (1970) models are often used to capture the autoregressive moving average of past observations of tourist arrivals from Japan to Taiwan and New Zealand. However, other explanatory variables, such as real income in the origin country, have also affected the demand for international travel. The purpose of this paper is to use the ARMAX model to investigate the dynamic relationship between tourism demand and real income of Japan, and to compare the findings with the single-equation model. Unit root tests and diagnostics are performed before estimating the income elasticity of travel demand by Japan for New Zealand and Taiwan based on seasonally unadjusted quarterly data for 1980(1) to 2004(2). The empirical results of the ARMAX model support the economic theory that the demand for international travel is positively related to income of the origin country. 相似文献
79.
Proteomics has long been thought to hold the promise of producing results of clinical utility which will influence patient treatment and outcomes. A recent Wellcome Trust/EBI meeting and retreat--“Perspectives in Clinical Proteomics”--brought together experts from a broad range of stakeholder groups with an interest in ensuring proteomics achieves this aim. This viewpoint presents views derived from these forums, proposing a pathway for the development of next-generation proteomic analyses in the clinical setting from selection of candidates through to their validation and ultimate demonstration of utility through health technology assessments. Although not meant to be all encompassing, important elements for proteomics researchers to consider are presented. 相似文献
80.
Qiusheng Wu Haibin Su Douglas J. Sherman Hongxing Liu Jennifer M. Wozencraft Bailang Yu 《International journal of remote sensing》2016,37(20):4854-4873
Hurricanes and tropical storms are severe threats to coastal properties, settlements, and infrastructure. Airborne light detection and ranging (lidar) surveys conducted before and after storm events allow detailed analysis of coastal geomorphologic and sediment volumetric changes and have been proved very useful in the study of coastal changes. Traditionally, most studies use the pixel-based differencing method to quantify the spatial extent and magnitude of coastal changes based on sequential lidar surveys. This research presents a graph theory-based approach and associated software tools for representing and quantifying storm-induced damages to buildings, beaches and sand dunes, coastal vegetation canopy, and infrastructure. Generation of elevation difference grids, construction of local contour trees, and derivation of semantic properties are key components of the new algorithm for change object detection and extraction. An ontology and taxonomy are proposed to classify change objects into different types of coastal damages in terms of their semantic properties. This method has been successfully applied to assess damages of Hurricane Ike to the Bolivar Peninsula on the Texas Gulf Coast based on pre- and post-storm airborne lidar data and colour infrared aerial photographs. 相似文献