检索结果-南通市图书馆

Review of computational Approaches to Optimization Problems in Inhomogeneous Rods and Plates

中国土木工程学会第九届土力学及岩土工程学术会议

作者： c.W.W.NG c.f.chiu The Hong Kong University of Science and Technology Clear Water Bay HKSAR China

failures of initially loose unsaturated man- made (or fill) slopes due to rainfall infiltration are not uncommon in many parts of the world. Some of these failures are reported as caused by static liquefaction. However, the behaviour and the transformation from initially loose unsaturated to saturated states of soils, well - graded decomposed material in particular, are not fully understood and correctly modelled. The word "loose" refers to the state of soil lies on the wet (or loose) side of the critical state (cS). In this paper, the stress -strain relationship, shear and volumetric behaviour of two common fill materials (i. e. , coarse grained decomposed granite (DG) and fine- grained decomposed volcanic (DV)) in Hong Kong are reviewed. Based on the results of three series of triaxial tests on both saturated and unsaturated IDG and DV, a new state - dependent elasto- plastic constitutive model for unsaturated soils is formulated and presented. Saturated soil behaviour is regarded as a special case of unsaturated soil phenomenon at zero suction. The model, which is developed under the extended critical state framework, uses two independent stress state variables including the net normal stress and matric suction. The influence of internal state (stress level and density) on dilatancy is incorporated by using a state - dependent dilatancy formulation. With this new model, numerical simuktions of the three series of triaxial tests are carried out on both saturated and unsaturated DG and DV and compared with experimental observations. The computed results show that the stress - strain and volumetric - axial strain relationships of the saturated and unsaturated DG and DV at the loose and dense states can be captured properly by the model using a single set of parameters. Moreover, the model is able to simulate some key aspects of material behaviour such as a sudden increase in axial strain and volumetric strain as suction is reduced under a constant deviator stress, w

关键词： constitutive modeling loose fill state dependent dilatancy unsaturated

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

communications on Applied Mathematics and computation 2024年第1期6卷 236-256页

作者： Weitao chen chiu-Yen Kao Department of Mathematics University of California at Riverside900 University AveRiversideCA92521USA Department of Mathematical Sciences Claremont McKenna College850 Columbia AveClaremontCA91711USA

In this paper,we review computational approaches to optimization problems of inhomogeneous rods and *** consider both the optimization of eigenvalues and the localization of *** problems are motivated by physical problems including the determination of the extremum of the fundamental vibration frequency and the localization of the vibration *** demonstrate how an iterative rearrangement approach and a gradient descent approach with projection can successfully solve these optimization problems under different boundary conditions with different densities given.

关键词： Inhomogeneous rods and plates Bi-Laplacian Optimization of eigenvalues Localization of eigenfunctions Rearrangement

“If Somebody Needed Help, I Went Over”: Social capital and Therapeutic communities of Older Adult farmers in British columbia floods

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Disaster Risk Science 2024年第2期15卷 290-301页

作者： Kyle Breen Siyu Ru Luna Vandeweghe Jenna chiu Lindsay Heyland Haorui Wu School of Social Work Dalhousie UniversityHalifaxNS B3H 1S2Canada

Older adults in disaster contexts are often thought of as a passive, vulnerable population that lacks agency and capacities to cope in the aftermath. However, it can be argued that older adults may have underrecognized strengths that can be utilized pre-, peri-, and post-disaster. One of these strengths is older adults' unique social capital that stems from long-standing connections with other members of their respective communities. Using data from in-depth, semistructured interviews with farmers in British columbia 3–11 months after the 2021 floods, this research explored the experiences of older adult farmers' recovery. The farmers discussed how they leveraged their social capital to aid in their recovery efforts from the flood event. By using their bonding social capital, older adult farmers transformed their existing, deep-rooted connections into post-disaster assistance. This, in turn, generated the idea of the therapeutic community, helping community members cope in the aftermath. This research indicated the need to further examine how older adults in disaster settings can be viewed as assets with community knowledge and skills as opposed to solely as a vulnerable population.

关键词： British columbia flood disaster Older adults Qualitative research Social capital Therapeutic community

classification of high-ordered topological nodes towards Moiré flat bands in twisted bilayers

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2024年第9期Mechanics & Astronomy) .卷 137-151页

作者： fan cui congcong Le Qiang Zhang Xianxin Wu Jiangping Hu ching-Kai chiu Beijing National Laboratory for condensed Matter Physics Institute of PhysicsChinese Academy of Sciences School of Physical Sciences University of Chinese Academy of Sciences RIKEN Interdisciplinary Theoretical and Mathematical Sciences(iTHEMS) cAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of Sciences Kavli Institute of Theoretical Sciences University of Chinese Academy of Sciences New cornerstone Science Laboratory

At magic twisted angles, Dirac cones in twisted bilayer graphene(TBG) can evolve into flat bands, serving as a critical playground for the study of strongly correlated physics. When chiral symmetry is introduced, rigorous mathematical proof confirms that the flat bands are locked at zero energy in the entire Moiré Brillouin zone(BZ). Yet, TBG is not the sole platform that exhibits this absolute band flatness. central to this flatness phenomenon are topological nodes and their specific locations in the BZ. In this study, considering twisted bilayer systems that preserve chiral symmetry, we classify various ordered topological nodes in base layers and all possible node locations across different BZs. Specifically, we constrain the node locations to rotational centers,such as Γ and M points, to ensure the interlayer coupling retains equal strength in all directions. Using this classification as a foundation, we systematically identify the conditions under which Moiré flat bands emerge. Additionally, through the extension of holomorphic functions, we provide proof that flat bands are locked at zero energy, shedding light on the origin of the band flatness. Remarkably, beyond Dirac cones, numerous twisted bilayer nodal platforms can host flat bands with a degeneracy number of more than two, such as four-fold, six-fold, and eight-fold. This multiplicity of degeneracy in flat bands might unveil more complex and enriched correlation physics.

关键词： twisted bilayer systems high-ordered topological nodes Morié flat bands high degeneracy

同方期刊数据库

Detecting fake reviewers in heterogeneous networks of buyers and sellers:a collaborative training-based spammer group algorithm

在线全文

学校读者我要写书评

暂无评论

cybersecurity 2024年第2期7卷 44-67页

作者： Qi Zhang Zhixiang Liang Shujuan Ji Benyong Xing Dickson K.W.chiu Shandong Provincial Key Laboratory of Wisdom Mine Information Technology Shandong University of Science and TechnologyQingdao 266590ShandongChina Zhejang University-University of linois at Urbana-champaign Institute Haining 314499ZhejiangChina School of civil Engineering Beijing Jiaotong UniversityBeijing 100044China faculty of Education The University of Hong KongPok Fu LamHong KongChina

It is not uncommon for malicious sellers to collude with fake reviewers(also called spammers)to write fake reviews for multiple products to either demote competitors or promote their products'reputations,forming a gray industry *** detect spammer groups in a heterogeneous network with rich semantic information from both buyers and sellers,researchers have conducted extensive research using frequent Item Mining-based and graph-based ***,these methods cannot detect spammer groups with cross-product attacks and do not jointly consider structural and attribute features,and structure-attribute correlation,resulting in poorer detection ***-fore,we propose a collaborative training-based spammer group detection algorithm by constructing a heterogene-ous induced sub-network based on the target product set to detect cross-product attack spammer *** jointly consider all available features,we use the collaborative training method to learn the feature representations of *** addition,we use the DBScAN clustering method to generate candidate groups,exclude innocent ones,and rank them to obtain spammer *** experimental results on real-world datasets indicate that the overall detection performance of the proposed method is better than that of the baseline methods.

关键词： Spammer group Heterogeneous network collaborative training DBScAN

Introduction of rare-earth element Sc in alloy design to modify wear features of dual-phase high-entropy alloy

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2024年第2期43卷 817-828页

作者： Hao Ren Rui-Run chen Xue-feng Gao Tong Liu Gang Qin Yu-Lung chiu Shi-Ping Wu Jing-Jie Guo Guo National Key Laboratory for Precision Hot Processing of Metals School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin150001China School of Metallurgy and Materials University of BirminghamBirminghamB152TTUK

Tailoring the alloy composition,which induces the hard secondary phase to increase hardness and strength to improve the wear features,is a feasible approach for developing wear-resistant metal ***,a group of(AlcocrfeNi)_(100–x)Sc_(x)(x=0–2.0,at%)high-entropy alloys(HEAs)are designed and the phase compositions and wear behaviors are ***-doped HEA series contain the primary body-centered cubic(Bcc)and eutectic phases,in which the eutectic phase is composed of the alternately grown Bcc and Laves *** addition promotes the diffusion of Ni atoms from Bcc phase to form the Sc-rich Laves phase at the grain *** hardness increases due to solid solution strengthening and second phase *** the second phase strengthening plays a more significant role relative to solid solution *** phase and the oxides caused by wear heating prevent the direct contact between friction pair and HEAs,thus inducing a decreased wear rate from 6.82×10^(−5) to 3.47×10^(−5)m^(3)·N^(−1)·m^(−1).Moreover,the wear mechanism changes from adhesive wear,abrasive wear and oxidative wear to abrasive wear and oxidative wear.

关键词： High entropy alloy(HEA) Laves phase Hardness Wear mechanism

A Hf-doped dual-phase high-entropy alloy: phase evolution and wear features

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第1期43卷 324-333页

作者： Hao Ren Rui-Run chen Xue-feng Gao Tong Liu Gang Qin Yu-Lung chiu Shi-Ping Wu Jing-Jie Guo National Key Laboratory for Precision Hot Processing of Metals School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China School of Metallurgy and Materials University of BirminghamEdgbastonBirmingham B152TTUK

Initially defined high entropy alloys(HEAs)usually exhibit a single-phase solid-solution ***,two and/or more types of phases in HE As possibly induce the desired microstructure features,which contribute to improving the wear properties of HE ***,we prepare a series of(AlcocrfeNi)_(100-x)Hf_(x)(x=0,2,4and 6;at%) HEAs and concern their phase compositions,micro structures and wear *** leads to the formation of(Ni,co)_(2)Hf-type Laves phase and tailors the microstructure from a body-centered cubic(Bcc) singlephase structure to a hypoeutectic *** increased hardness from~HV 512.3 to~HV 734.1 is due to solid-solution strengthening,grain refinement strengthening and precipitated phase *** a few oxides(Al_(2)O_(3)+cr_(2)O_(3)) caused by the wear heating contribute to an 85.5% decrease in wear rate of the HEA system from6.71×10^(-5) to 0.97×10^(-5) m^(3)·N^(-1)·m^(-1).In addition,Hf addition changes the wear mechanism from abrasive wear,mild oxidative wear and adhesive wear to oxidative wear and adhesive wear.

关键词： High entropy alloy Laves phase Hardness Wear mechanism

Effects of dust controls on respirable coal mine dust composition and particle sizes:case studies on auxiliary scrubbers and canopy air curtain

在线全文

学校读者我要写书评

暂无评论

International Journal of coal Science & Technology 2024年第3期11卷 86-101页

作者： f.Animah c.Keles W.R.Reed E.Sarver Department of Mining and Minerals Engineering Virginia Polytechnic Institute&State UniversityBlacksburgVAUSA National Institute of Occupational Safety and Health(NIOSH) PittsburghPAUSA

control of dust in underground coal mines is critical for mitigating both safety and health *** decades,the National Institute of Occupational Safety and Health(NIOSH)has led research to evaluate the effectiveness of various dust control technologies in coal *** studies have included the evaluation of auxiliary scrubbers to reduce respirable dust downstream of active mining and the use of canopy air curtains(cAcs)to reduce respirable dust in key operator *** detailed dust characterization was not a focus of such studies,this is a growing area of *** preserved filter samples from three previous NIOSH studies,the current work aims to explore the effect of two different scrubbers(one wet and one dry)and a roof bolter cAc on respirable dust composition and particle size *** this,the preserved filter samples were analyzed by thermogravimetric analysis and/or scanning electron microscopy with energy dispersive *** indicate that dust composition was not appreciably affected by either scrubber or the ***,the wet scrubber and cAc appeared to decrease the overall particle size *** an effect of the dry scrubber was not consistently observed,but this is probably related to the particular sampling location downstream of the scrubber which allowed for significant mixing of the scrubber exhaust and other return *** from the insights gained with respect to the three specific dust control case studies revisited here,this work demonstrates the value of preserved dust samples for follow-up investigation more broadly.

关键词： Respirable dust Dust control SEM–EDX Scrubber canopy air curtain Silica

All-electron basis sets for H to Xe specific for ZORA calculations:Applications in atoms and molecules

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

chinese Physics B 2024年第8期33卷 238-246页

作者： c.S.Gomes f.E.Jorge A.canal Neto Departamento de fisica Universidade Federal do Espirito Santo29075-910 VitoriaESBrazil Departamento de fisica Instituto de Ciencias Exatas e BiologicasUniversidade Federal de Ouro Preto Campus Universitario Morro do Cruzeiro35402-136 Ouro PretoMGBrazil

A segmented basis set of quadruple zeta valence quality plus polarization functions(QZP)for H through Xe was developed to be used in conjunction with the ZORA *** set was augmented with diffuse functions to describe electrons farther away from the nuclei *** the ZORA-ccSD(T)/QZP-ZORA theoretical model,atomic ionization energies and bond lengths,harmonic vibrational frequencies,and atomization energies of some molecules were *** addition of core-valence corrections has been shown to improve the agreement between theoretical and experimental results for molecular *** atomization energies,a similar observation emerges when considering spin-orbit *** the augmented QZP-ZORA set,static mean dipole polarizabilities of a set of atoms were calculated and compared with previously published recommended and experimental *** evaluations of the ZORA and Douglas–Kroll–Hess Hamiltonians were made for each property studied.

关键词： QZP-ZORA and AQZP-ZORA basis sets elements from H to Xe ccSD(T)method atomic and molecular properties