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A stabilized complementarity formulation for nonlinear analysis of 3D bimodular materials

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Acta Mechanica Sinica 2016年第3期32卷 481-490页

作者： l.zhang H.W.zhang J.Wu B.Yan Department of Engineering Mechanics College of AerospaceEngineering Chongqing University State Key laboratory of Structural Analysis for IndustrialEquipment Dalian University of Technology

Bi-modulus materials with different mechanical responses in tension and compression are often found in civil,composite, and biological engineering. Numerical analysis of bimodular materials is strongly nonlinear and convergence is usually a problem for traditional iterative schemes. This paper aims to develop a stabilized computational method for nonlinear analysis of 3D bimodular materials. Based on the parametric variational principle, a unified constitutive equation of 3D bimodular materials is proposed, which allows the eight principal stress states to be indicated by three parametric variables introduced in the principal stress *** original problem is transformed into a standard linear complementarity problem（lCP） by the parametric virtual work principle and a quadratic programming algorithm is developed by solving the lCP with the classic lemke＇s algorithm. Update of elasticity and stiffness matrices is avoided and, thus, the proposed algorithm shows an excellent convergence behavior compared with traditional iterative *** examples show that the proposed method is valid and can accurately analyze mechanical responses of 3D bimodular materials. Also, stability of the algorithm is greatly improved.

关键词： Bimodular materials Non-smooth stressstrain relationship Parametric variational principle Complementarity

DISCOVERY OF lATENT STRUCTURES: EXPERIENCE WITH THE COIl CHAllENGE 2000 DATA SET

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Journal of Systems Science & Complexity 2008年第2期21卷 172-183页

作者： Nevin l.zhang Department of Computer Science and Engineering The Hong Kong University of Science and Technology

The authors present a case study to demonstrate the possibility of discovering complex and interesting latent structures using hierarchical latent class （HlC） models. A similar effort was made earlier by zhang （2002）, but that study involved only small applications with 4 or 5 observed variables and no more than 2 latent variables due to the lack of efficient learning algorithms. Significant progress has been made since then on algorithmic research, and it is now possible to learn HlC models with dozens of observed variables. This allows us to demonstrate the benefits of HlC models more convincingly than before. The authors have successfully analyzed the CoIl Challenge 2000 data set using HlC models. The model obtained consists of 22 latent variables, and its structure is intuitively appealing. It is exciting to know that such a large and meaningful latent structure can be automatically inferred from data.

关键词： Bayesian networks case study latent structure discovery learning.

Distribution of tetraether lipids in surface sediments of the northern South China Sea:Implications for TEX_(86) proxies

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Geoscience Frontiers 2013年第2期4卷 223-229页

作者： Huangmin Ge Chuanlun l.zhang Hongyue Dang Chun Zhu Guodong Jia State Key laboratory of Marine Geology Tongji University Department of Marine Sciences University of Georgia State Key laboratory of Heavy Oil Processing & Centre for Bioengineering and Biotechnology China University of Petroleum(East China) MARUM Center for Marine Environmental Sciences and Department of Geosciences University of Bremen CAS Key laboratory of Marginal Sea Geology Guangzhou Institute of GeochemistryChinese Academy of Sciences

Archaea have unique glycerol dialkyl glycerol tetraether（GDGT） lipids that can be used to develop paleotemperature proxies such as *** research is to validate proposed GDGT-proxies for paleotemperature determination in the South China Sea（SCS）.Samples were collected from core-top sediments （0-5 cm） in the northern *** lipids were extracted to obtain core GDGTs,which were identified and quantified using liquid chromatography-mass spectrometry（lC-MS）.The abundance of isoprenoidal GDGTs（/GDGTs） ranged from 271.5 ng/g dry sediment to 1266.3 ng/g dry sediment,whereas the branched GDGTs（bGDGTs）,supposedly derived from terrestrial sources,ranged from 22.2 ng/g dry sediment to 56.7 ng/g dry *** TEX_（86）-derived sea surface temperatures ranged from 20.9℃in the coast（water depth 〈 160 m） to 27.9℃offshore（water depth 〉 1000 m）.TEX86-derived temperatures near shore（〈 160 m water depth） averaged 23.1±2.5℃（n =4）,which were close to the satellite-derived winter mean sea surface temperature（average 22.6±1.0℃,n = 4）;whereas the TEX_（86）-derived temperatures offshore averaged 27.4±0.3℃（n = 7） and were consistent with the satellite mean annual sea surface temperature（average 26.8±0.4℃,n = 7）.These results suggest that TEX_（86） may record the sea surface mean annual temperature in the open ocean,while it likely records winter sea surface temperature in the shallower water.

关键词： Archaea GDGTs TEX86 Paleotemperature Northern South China Sea

Combining multiple imperfect data sources for small area estimation:a Bayesian model of provincial fertility rates in Cambodia

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Statistical Theory and Related Fields 2019年第2期3卷 178-185页

作者： Junni l.zhang John Bryant Guanghua School of Management Center for Statistical Science and Center for Data SciencePeking UniversityBeijingPeople’s Republic of China Bayesian Demography limited ChristchurchNew Zealand

Demographic estimation becomes a problem of small area estimation when detaileddisaggregation leads to small cell *** usual difficulties of small area estimation are compounded when the available data sources contain measurement *** present a Bayesianapproach to the problem of small area estimation with imperfect data *** overall modelcontains separate submodels for underlying demographic processes and for measurement *** unknown quantities in the model,including coverage ratios and demographic rates,are estimated jointly via Markov chain Monte Carlo *** approach is illustrated usingthe example of provincial fertility rates in Cambodia.

关键词： Measurement error Bayesian hierarchical model coverage errors fertility Cambodia small area estimation

Distribution of glycerol dialkyl glycerol tetraethers in Tibetan hot springs

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Geoscience Frontiers 2012年第3期3卷 289-300页

作者： liu He Chuanlun l.zhang Hailiang Dong Bin Fang Genhou Wang State Key laboratory of Marine Geology Tongji UniversityShanghai 200092China Department of Marine Sciences the University of GeorgiaAthensGA 30602USA Department of Geology Miami UniversityOxfordOHUSA Geomicrobiology laboratory the Geological Lab CenterChina University of GeosciencesBeijing 100083China School of Water Resources and Environment China University of GeosciencesBeijing 100083China

Isoprenoidal glycerol dialkyl glycerol tetraethers （iGDGTs） from the Gulu hot springs （23--83.6 ℃, pH 〉 7） and Yangbajing hot springs （80-128 ℃, pH 〉 7） were analyzed in order to investigate the distribution of archaeal lipids among different hot springs in Tibet. A soil sample from Gulu was incubated at different temperatures and analyzed for changes in iGDGTs to help evaluate whether surrounding soil may contribute to the iGDGTs in hot springs. The sources of bacterial GDGTs （bGDGTs） in these hot springs were also investigated. The results revealed different profiles ofiGDGTs between Gulu and Yangbajing hot springs. Core iGDGTs and polar iGDGTs also presented different patterns in each hot spring. The PCA analysis showed that the structure of polar iGDGTs can be explained by three factors and suggested multiple sources of these compounds. Bivariate correlation analysis showed significant positive correlations between polar and core bGDGTs, suggesting the in situ production of bGDGTs in the hot springs. Furthermore, in the soil incubation experiment, temperature had the most significant influence on concentration of bGDGTs rather than iGDGTs, and polar bGDGTs had greater variability than core bGDGTs with changing temperature. Our results indicated that soil input had little influence on the composition of GDGTs in Tibetan hot springs.

关键词： Glycerol dialkyl glyceroltetraethers (GDGTs) Tibet Hot springs Branched and isoprenoidtetraethers (BITs) TEX86

TRANSMISSION ElECTRON MICROSCOPY INVESTIGATIONS OF lOW-PRESSURE CVD GROWTH AND STRAIN RElAXATION OF Ge ISlANDS ON Si(110)

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Acta Metallurgica Sinica(English letters) 2005年第3期18卷 427-432页

作者： E.Spiecker l.zhang H.M.lu W.Jaeger l.Vescan MicroanalysisofMaterials FacultyofEngineeringChrisfian-Albrechts-UniversityKielKaiserstraβe224143KielGermany InstituteofThinFilmsandInterfaces ResearchCenterJiilichGmbH52425JiilichGermany

Shapes, dimensions, arrangements and the microstructure of self-assembled island s fabricated by low-pressure chemical vapour deposition (lPCVD) of Ge at 700℃ o nto Si(110) substrates have been investigated for different nominal Ge coverage by transmission electron microscopy (TEM) of plan-view and cross-section specime ns and have been compared with photoluminescence (Pl) measurements of Si-capped layer samples. The transition from the 2-dimensional layer to the 3-dimensional island growth mode takes place for a Ge deposition of nominally less than 2 mono layers. Upon this transition, many coherent islands and few larger islands with extended defects are observed. The coherent islands possess a dome-like shape an d lateral sizes up to 130nm. Photoluminescence spectra show island-related peaks whose energy positions are shifted towards lower energy with higher Ge coverage .

关键词： Si-Ge heteroepitaxy surface transmission electron microscopy Nanostructure

Influence of high configuration entropy on damping behaviors of Ti-Zr-Hf-Ni-Co-Cu high entropy alloys

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Journal of Materials Science & Technology 2023年第22期153卷 242-253页

作者： W.Q.Wu l.zhang K.K.Song J.M.Pelletier H.F.zhang J.C.Qiao School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an 710072China Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Mechanical and Electrical Engineering Shandong UniversityWeihai 264209China Universitéde lyon MATEISUMR CNRS5510Bat.B.PascalINSA-LyonVilleurbanne Cedex F-69621France Chongqing Science and Technology Innovation Center of NPU Chongqing 401135China

TiNi-based shape memory alloys(SMAs)have been used as damping materials to eliminate noise and mechanical ***,their application is limited by low working temperatures and damping *** this work,two novel Ti-Zr-Hf-Ni-Co-Cu high entropy shape memory alloys(HESMAs)with different transformation temperatures and damping properties were *** results show that Ti_(25)Zr_(8)Hf_(17)Ni_(30)Co_(5)Cu_(15) has superior damping performance arising from martensitic transformation,shape memory effect(thermal cycle at constant load)as well as *** to traditional TiNi-based SMAs,the as-cast HESMAs exhibit a much higher ultrahigh yield strength(∼2 GPa)and storage modulus(∼50 GPa).The high configuration entropy of the HESMAs with high uneven internal stress and severe lattice distortion is revealed as the underlying mechanisms governing distinctive damping *** effects of high configuration entropy and microheterogeneity on the martensitic transforma-tion behavior and damping performance of HESMAs are clarified in this work,which provides a basis for designing alloys with superior damping properties.

关键词： High entropy s hape memory alloy Internal friction Damping Configuration entropy Martensitic transformation

Model predictive control for water management and energy security in arid/semiarid regions

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Journal of Automation and Intelligence 2022年第1期1卷 55-67页

作者： D.M.Bajany l.zhang X.Xia Department of Electrical Electronic and Computer EngineeringUniversity of PretoriaPretoria 0002South Africa School of Artificial Intelligence and Automation Huazhong University of Science and TechnologyWuhan 430074China

This paper aims to develop a realistic operational optimal management of a water supply system in an arid/semiarid region under climate change *** developed model considers the dynamic variation of water demand,rainfall,weather,and seasonal change in electricity *** is mathematically developed as a multi-constraint non-linear programming model based on model predictive control *** model optimises the quantities of water supplied by each source every month and improves the energy efficiency in a water supply system with multiple types of *** effectiveness of the developed MPC model is verified by applying it to a case study and comparing the results with those obtained with an open loop *** showed that using the MPC model leads to a 4.16%increase in the water supply cost compared to the open loop ***,when considering uncertainties in predicting water demands,aquifer recharges,rainfall,and evaporation rate,the MPC model was better than the open loop ***,the MPC model could meet the water demand at any period due to its predictability of variations,which was not the case with the open loop ***,a sensitivity analysis is conducted to verify the capacity of the developed model to deal with some phenomena due to climatic changes,such as in rainfall.

关键词： Water supply management Model predictive control Energy-water nexus

Integrating modelling and remote sensing to identify ecosystem performance anomalies in the boreal forest,Yukon River Basin,Alaska

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International Journal of Digital Earth 2008年第2期1卷 196-220页

作者： B.K.Wylie l.zhang N.Bliss l.Ji l.l.Tieszen W.M.Jolly SAIC USGS Earth Resources Observation and Science(EROS)CenterSioux FallsSD 57198USA.Work performed under USGS contract 03CRCN0001 USGS EROS Center Sioux FallsSD 57198USA USDA Forest Service Fire Sciences LaboratoryMissoulaMT59808

High-latitude ecosystems are exposed to more pronounced warming effects than other parts of the *** develop a technique to monitor ecological changes in a way that distinguishes climate influences from *** this study,we account for climatic influences on Alaskan boreal forest performance with a datadriven *** defined ecosystem performance anomalies(EPA)using the residuals of the model and made annual maps of *** areas(88%)did not have anomalous ecosystem performance for at least 6 of 8 years between 1996 and *** with underperforming EPA(10%)often indicate areas associated with recent fires and areas of possible insect infestation or drying soil related to permafrost *** areas(2%)occurred in older fire recovery areas where increased deciduous vegetation components are *** EPA measure was validated with composite burn index data and landsat vegetation indices near and within burned areas.

关键词： climate change anomaly performance boreal Alaska Yukon River