检索结果-南通市图书馆

Contribution of Fluid Dynamics to Woodwind Instruments Investigations of Timbre and Pitch of Bassoon Bocals

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal Science 2005年第3期14卷 264-266页

作者： Roger GRUNDMANN johannes BAUMGART Andreas RICHTER Hans KRüGER Technische Universitt Dresden Institute for Aerospace Engineering D-01062 Dresden Germany ProfessorTechnische Universitt Dresden Institute for Aerospace Engineering D-01062 Dresden GermanyTechnische Universitt Dresden Institute for Aerospace Engineering D-01062 Dresden GermanyTechnische Universit?t Dresden Institute for Aerospace Engineering D-01062 Dresden Germany

The discussed topic of isolating certain parameters which describe the timbre in connection with bocals of bassoons is of major interest for manufacturers and artist likewise since a reduction in the overall shear stress of these kinds of technical diffusors is very helpful but not sufficient. The timbre seen from the side of the musician has to be the same. Up to now two criteria have been isolated which have a deep influence on the easier blowing of the bassoon and on the comparable timbre due to geometrical reasons. If the geometrical outer contour is designed carefully, it is possible to modify the shape and preserve the timbre.

关键词：气体动力学木管乐器孤立参数音质

DIRECT MINIMIZATION FOR CALCULATING INVARIANT SUBSPACES IN DENSITY FUNCTIONAL COMPUTATIONS OF THE ELECTRONIC STRUCTURE

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2009年第2期27卷 360-387页

作者： Reinhold Schneider Thorsten Rohwedder Alexey Neelov johannes Blauert Institute for Mathematics Technical University BerlinStraβe des 17.Juni 13510623 BerlinGermany Institute of Physics University of BaselKlingelbergstrasse 824056 BaselSwitzerland Institute for Mathematics Technical University BerlinStraβe des 17. Juni 13510623 BerlinGermany

In this article, we analyse three related preconditioned steepest descent algorithms, which are partially popular in Hartree-Fock and Kohn-Sham theory as well as invariant subspace computations, from the viewpoint of minimization of the corresponding functionals, constrained by orthogonality conditions. We exploit the geometry of the admissible manifold, i.e., the invariance with respect to unitary transformations, to reformulate the problem on the Grassmann manifold as the admissible set. We then prove asymptotical linear convergence of the algorithms under the condition that the Hessian of the corresponding Lagrangian is elliptic on the tangent space of the Grassmann manifold at the minimizer.

关键词： Eigenvalue computation Grassmann manifolds Optimization Orthogonalityconstraints Hartree-Fock theory Density functional theory PINVIT

New approaches to water purification for resource- constrained settings： Production of activated biochar by chemical activation with diammonium hydrogenphosphate

在线全文

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2018年第1期12卷 194-208页

作者： Mohit Nahata Chang Y. Seo Pradeep Krishnakumar johannes Schwank Department of Chemical Engineering University of Michigan-Ann Arbor Ann Arbor MI 48109 USA

A significant portion of the world＇s population does not have access to safe drinking water. This problem is most acute in remote, resource-constrained rural settings in developing countries. Water filtration using activated carbon is one of the important steps in treating con- taminated water. Lignocellulosic biomass is generally available in abundance in such locations, such as the African rain forests. Our work is focused on developing a simple method to synthesize activated biochar from locally available materials. The preparation of activated biochar with diammonium hydrogenphosphate （DAP） as the activating agent is explored under N2 flow and air. The study, carried out with cellulose as a model biomass, provides some insight into the interaction between DAP and biomass, as well as the char forming mechanism. Various characterization techniques such as N2 physisorption, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy are utilized to compare the properties between biochar formed under nitrogen and partial oxidative conditions. At a temperature of 450 ℃, the loading of DAP over cellulose is systematically varied, and its effect on activation is examined. The activated biochar samples are predominantly microporous in the range of concentrations studied. The interaction of DAP with cellulose is investigated and the nature of bonding of the heteroatoms to the carbonaceous matrix is elucidated. The results indicate that the quality of biochar prepared under partial oxidation condition is comparable to that ofbiochar prepared under nitrogen, leading to the possibility of an activated biochar production scheme on a small scale in resource-constrained settings.

关键词： cellulose DAP activation heteroatom,microporous

Diversity of wing patterns and abdomen-generated substrate sounds in 3 European scorpionfly species

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Insect Science 2015年第4期22卷 521-531页

作者： Manfred Hartbauer johannes Gepp Karin Hinteregger Stephan Koblmuller Institute of Zoology KarI-Franzens-University Graz Universitatsplatz 2 8010 Graz Institute for Nature Conservation Herdergasse 3 8010 Graz Austria

In the genus Panorpa （Insecta： Mecoptera）, also known as scorpionflies, pre- mating behavior includes repeated sequences of slow wing movements （waving, fanning, flagging） which are accompanied by rapid abdomen vibrations that generate substantial substrate-borne sound. It is still unknown whether wing patterns or vibratory signals contain information about species identity, sex and/or the quality of potential mating part- ners. Besides species-specific pheromones, these multimodal signals may be of particular importance for the maintenance of reproductive isolation in sympatrically occurring scor- pionfly species. Here, we analyzed phyologenetic relationships among, and the pattern of forewings as well as substrate-borne sound in 3 different sympatric Central-European scorpionfly species （P communis, P germanica, and P alpina）. Divergence time estimates, based on 879 bp of the mitochondrial COI gene, indicate longstanding separate evolu- tionary histories for the studied Panorpa species. Morphological analysis revealed that wing length as an indicator of body size increased in the following order： P alpina 〈 P. germanica 〈 P. communis. Individuals can be assigned to the correct species and sex with high accuracy just by evaluation of the number of dark spots and the proportion of wing pigmentation. Despite high variability of interpulse period at an individual level, across species analysis revealed a positive correlation of average interpulse period as well as mean signal amplitude with forewing length. These results suggest wing patterns, but less likely vibratory signals, to contain information about species identity. Furthermore, receivers may be able to estimate the body size of a signaler solely on the basis of substrate-borne sound.

关键词： courtship signals laser vibrometry phylogeny species recognition substrate-borne sound wing pattern

The Product of the Restrained Domination Numbers of a Graph and Its Complement

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2014年第3期30卷 445-452页

作者： johannes H.HATTINGH Ernst J.JOUBERT Department of Mathematics East Carolina University Department of Mathematics University of Johannesburg

Let G=（V,E） be a graph.A set S■V is a restrained dominating set if every vertex in V-S is adjacent to a vertex in S and to a vertex in *** restrained domination number of G,denoted γr（G）,is the smallest cardinality of a restrained dominating set of *** this paper,we show that if G is a graph of order n≥4,then γr（G）γr（G）≤*** also characterize the graphs achieving the upper bound.

关键词： Graph domination restrained domination Nordhaus-Gaddum upper bound

Exploring novel experimental treatments for major neurodegenerative disorders

在线全文

学校读者我要写书评

暂无评论

Neuroprotection 2023年第2期1卷 81-83页

作者： Xunming Ji Piotr Walczak johannes Boltze Beijing Institute of Brain Disorders Capital Medical UniversityBeijingChina Department of Diagnostic Radiology and Nuclear Medicine Center for Advanced Imaging ResearchUniversity of MarylandBaltimoreMarylandUSA School of Life Sciences University of WarwickCoventryUK

Acute and chronic neurodegenerative disorders such as ischemic stroke or Alzheimer's disease(AD)impose a major burden on patients,their relatives,caregivers,and health care systems in *** socioeconomic impact of neurodegenerative disorders is anticipated to escalate due to a globally ageing population and the increasing prevalence of sedentary lifestyle and inappropriate dietary *** the contrary.

关键词： Alzheimer's disease amyotrophic lateral sclerosis cell therapy cytoprotection extracellular vesicles neurodegeneration stroke

Routing through open spaces-A performance comparison of algorithms

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geo-Spatial Information Science 2018年第3期21卷 247-256页

作者： Stefan Hahmann Jakob Miksch Bernd Resch johannes Lauer Alexander Zipf GIScience Research Group Institute of GeographyHeidelberg UniversityHeidelbergGermany Fraunhofer IVI Fraunhofer Institute for Transportation and Infrastructure SystemsDresdenGermany Department of Geoinformatics-Z_GIS University of SalzburgAustria Center for Geographic Analysis Harvard UniversityCambridgeMAUSA HERE GmbH&Co KG Schwalbach am TaunusGermany

Finding the shortest path through open spaces is a well-known challenge for pedestrian routing engines.A common solution is routing on the open space boundary,which causes in most cases an unnecessarily long route.A possible alternative is to create a subgraph within the open *** paper assesses this approach and investigates its implications for routing engines.A number of algorithms(Grid,Spider-Grid,Visibility,Delaunay,Voronoi,Skeleton)have been evaluated by four different criteria:(i)Number of additional created graph edges,(ii)additional graph creation time,(iii)route computation time,(iv)routing *** show that each algorithm has advantages and disadvantages depending on the use *** identify the algorithms Visibility with a reduced number of edges in the subgraph and Spider-Grid with a large grid size to be a good compromise in many scenarios.

关键词： OpenStreetMap routing open space navigation pedestrian polygon

Quantum security analysis of a lattice-based oblivious transfer protocol

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Information Technology & Electronic Engineering 2017年第9期18卷 1348-1369页

作者： Mo-meng LIU Juliane KRAMER Yu-pu HU johannes BUCHMANN State Key Laboratory of Integrated Service Networks Xidian University Xi'an 710071 China Technische Universitiat Darrastadt Darmstadt 64289 Germany

不经意传输协议(oblivious transfer,OT)因其简易的密码功能广泛应用于安全多方计算。以往OT协议都是基于传统数论问题(例如,离散对数,大数分解问题)所构造的,随着量子计算技术的发展,基于传统困难问题的OT协议安全性受到极大的威胁。因... 详细信息

不经意传输协议(oblivious transfer,OT)因其简易的密码功能广泛应用于安全多方计算。以往OT协议都是基于传统数论问题(例如,离散对数,大数分解问题)所构造的,随着量子计算技术的发展,基于传统困难问题的OT协议安全性受到极大的威胁。因此,人们转而考虑使用后量子密码技术替代以往OT协议所依赖的传统困难问题。目前,已有一些基于后量子密码体制的OT协议被提出。然而,大多数后量子密码构造只在假设传统敌手存在的环境下证明其方案安全性。在本文中,我们在量子敌手存在的环境下,证明一个基于格公钥密码的OT协议([PVW08])的安全性。首先我们使用量子平移定理([Unr10])证明该协议的安全性可以完全平移到量子环境中,此外,我们还使用其他两个专用于分析后量子密码原语的分析模型([HSS11],[Son14])从不同的角度对该协议进行安全性分析,从而保证我们给出的量子安全证明的正确性。我们的成果可以看作对后量子密码协议分析模型的一个实际应用实例。

关键词：不经意传输后量子格公钥带差错学习通用可复合

Resistance to chemoimmunotherapy in non-small-cell lung cancer

在线全文

学校读者我要写书评

暂无评论

Cancer Drug Resistance 2020年第3期3卷 445-453页

作者： Maximilian johannes Hochmair Respiratory Oncology Unit Vienna North Hospital-Klinik FloridsdorfVienna 1210Austria.

Recent clinical trials evaluating the combination of chemotherapy with immune checkpoint inhibition for the primary treatment of lung cancer showed increased progression-free and overall survival compared with chemotherapy ***,the combination of these two modalities is less than additive and the mechanisms of resistance to this therapeutic intervention are discussed *** far,the conventional biomarkers for immunotherapy,namely programmed death-ligand 1 expression or tumor mutational burden are poor predictors of the efficacy of immunochemotherapy,and the optimal sequence of chemotherapy and immunotherapy has yet to be defined.

关键词： Lung cancer chemotherapy immunotherapy combination pembrolizumab resistance