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Granular behaviour under bi-directional shear with constant vertical stress and constant volume

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第10期16卷 4300-4318页

作者： Min zhang Yunming Yang hanwen zhang Qi Li School of Civil and Architectural Engineering Henan UniversityKaifeng475004China Department of Civil Engineering University of Nottingham Ningbo ChinaNingbo315100China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing 100049China

This paper aims to investigate the role of bi-directional shear in the mechanical behaviour of granular materials and macro-micro relations by conducting experiments and discrete element method(DEM)*** bi-directional shear consists of a static shear consolidation and subsequent shear under constant vertical stress and constant volume conditions.A side wall node loading method is used to exert bi-directional shear of various *** results show that bi-directional shear can significantly influence the mechanical behaviour of granular ***,the relationship between bidirectional shear and mechanical responses relies on loading conditions,*** vertical stress or constant volume *** stress states induced by static shear consolidation are affected by loading angles,which are enlarged by subsequent shear,consistent with the relationship between bidirectional shear and principal *** provides evidence for the dissipation of stresses accompanying static liquefaction of granular *** presence of bi-directional principal stress rotation(PSR)is demonstrated,which evidences why the bi-directional shear of loading angles with components in two directions results in faster dissipations of stresses with static *** volume shearing leads to cross-anisotropic stress and fabric at micro-contacts,but constant vertical stress shearing leads to complete anisotropic stress and fabric at *** explains the differentiating relationship between stress-strain responses and fabric anisotropy under these two *** signatures such as the slip state of micro-contacts and coordination number are also examined,providing further insights into understanding granular behaviour under bi-directional shear.

关键词： Granular material Bi-directional shear Constant vertical stress Constant volume Principal stress rotation(PSR) Anisotropy

Logcf: An Efficient Tool for Real Root Isolation

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Journal of Systems Science & Complexity 2019年第6期32卷 1767-1782页

作者： DAI Liyun FAN Zhe XIA Bican zhang hanwen RISE&School of Computer and Information Science Southwest UniversityChongqing 400700China LMAM&School of Mathematical Science Peking UniversityBeijing 100871China

Computing upper bounds of the positive real roots of some polynomials is a key step of those real root isolation algorithms based on continued fraction expansion and Vincent's *** authors give a new algorithm for computing an upper bound of positive roots in this *** complexity of the algorithm is O(n log(uH-l))additions and multiplications where u is the optimal upper bound satisfying Theorem 3.1 of this paper and n is the degree of the *** method together w辻h some tricks have been implemented as a software package logcf using C *** on many benchmarks show that logcf is competitive with Root Intervals of Mathematica and the function realroot of Maple averagely and it is much faster than existing open source real root solvers in many test cases.

关键词： Computer algebra continued fractions real root isolation univariate polynomial vincent's theorem

LOPE: A Low-Overhead Payment Verification Method for Blockchains

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Chinese Journal of Electronics 2021年第2期30卷 349-358页

作者： zhang Ying HE Zhengyuan JIA Linpeng DING Donghui zhang hanwen SUN Yi School of Software Engineering Tongji University Blockchain Lab Institute of Computing Technology Chinese Academy of Sciences School of Computer Science and Technology University of Chinese Academy of Sciences

With its characteristics of decentralization,security, data traceability, and tamper-resistance, the blockchain has been widely used in various *** the difference in the performance of the devices, the light client is proposed so that devices without the ability to store a full blockchain copy can also participate in the blockchain transactions. However,the light client has to communicate with full nodes and verify the authenticity of a transaction which brings in some extent of communication, computation, and storage overheads to the light client. These overheads cannot be ignored for some low-performance devices, such as embedded devices or Io T chips, and therefore the current light client scheme does not work in this situation. We propose LOPE(a Low-overhead payment v Erification method) for poor-capacity nodes in the blockchain *** LOPE, a grouping protocol is designed to partition full nodes into groups to serve the verification requests of the light client. In addition, Practical byzantine fault tolerance(PBFT) is used to ensure the light client to get a credible result in spite of a few dishonest nodes existing in the group. We conduct LOPE and evaluate it in a testbed. The experiment results show that LOPE reduces more than half of the communication overhead, degrades the computation overhead of the light client to a large extent, and avoids the storage overhead of the hash roots of block headers in the light client. We also conduct theoretical analysis to show the performance improvement and security issues of LOPE.

关键词： current light client scheme storage overhead blockchains Low-overhead payment vErification method peer-to-peer computing software fault tolerance electronic money data integrity LOPE low-performance devices cryptographic protocols fault tolerance blockchain transactions

Stochastic process-based degradation modeling and RUL prediction: from Brownian motion to fractional Brownian motion

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Science China(Information Sciences) 2021年第7期64卷 5-24页

作者： hanwen zhang Maoyin CHEN Jun SHANG Chunjie YANG Youxian SUN School of Automation and Electrical Engineering University of Science and Technology Beijing State Key Laboratory of Industrial Control Technology College of Control Science and EngineeringZhejiang University Department of Automation Tsinghua University School of Automation and Electrical Engineering Linyi University Department of Electrical and Computer Engineering University of Alberta

Brownian motion(BM) has been widely used for degradation modeling and remaining useful life(RUL) prediction, but it is essentially Markovian. This implies that the future state in a BM-based degradation process relies only on its current state, independent of the past states. However, some practical industrial devices such as Li-ion batteries, ball bearings, turbofans, and blast furnace walls show degradations with long-range dependence(LRD), where the future degradation states depend on both the current and past degradation states. This type of degradation naturally brings two interesting problems, that is, how to model the degradations and how to predict their RULs. Recently, in contrast to the work that uses only BM, fractional Brownian motion(FBM) is introduced to model practical degradations. The most important feature of the FBM-based degradation models is the ability to characterize the non-Markovian degradations with LRD. Although FBM is an extension of BM, it is neither a Markovian process nor a semimartingale. Therefore, how to obtain the first passage time of an FBM-based degradation process has become a challenging task. In this paper, a review of the transition of RUL prediction from BM to FBM is provided. The peculiarities of FBM when addressing the LRD inherent in some practical degradations are discussed. We first review the BM-based degradation models of the past few decades and then give details regarding the evolution of FBM-based research. Interestingly, the existing BM-based models scarcely consider the effect of LRD on the prediction of RULs. Two practical cases illustrate that the newly developed FBMbased models are more generalized and suitable for predicting RULs than the BM-based models, especially for degradations with LRD. Along with the direction of FBM-based RUL prediction, we also introduce some important and interesting problems that require further study.

关键词： remaining useful life degradation model Brownian motion fractional Brownian motion long-range dependence

Optimal MMSE successive interference cancellation in group-wise STBC MIMO systems

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Journal of Systems Engineering and Electronics 2006年第1期17卷 85-90页

作者： Fan Xun zhang Haibin Luo hanwen Huang Jianguo Dept. of Electronic Engineering Shanghai Jiaotong Univ. Shanghai 200030 P. R. China

An optimal minimum mean square error successive interference cancellation （OMMSE SIC） scheme for Groupwise space-time block coding （G-STBC） multiple-input multiple-output （MIMO） systems is presented. In such a system, transmit antennas are partitioned into several STBC encoding groups and each group transmits independent data stream which is individually STBC encoded. On the receiver side, by exploring the temporal constraint provided by STBC, an equivalent channel model similar to the one in standard vertical Bell laboratories layered space-time （V-BLAST） systems is generated. Then OMMSE SIC algorithm is performed to detect all the transmitted information. Simulation compares the proposed scheme with non-ordering MMSE SIC scheme and the corresponding equal data rate scheme in V-BLAST systems with the same receive antennas＇ number. Result shows that the proposed scheme has better performance than non-ordering MMSE SIC scheme and by introducing more transmit antennas and adopting the OMMSE SIC scheme, better performance also can be achieved than corresponding V-BLAST systems.

关键词： multi-input multi-output vertical Bell laboratories layered space-time space-time block coding minimum mean square error

The Hybrid Bidirectional DC/DC Converter:Mutual Control and Stability Analysis

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CSEE Journal of Power and Energy Systems 2023年第2期9卷 769-778页

作者： Haiyang Liu Shumei Cui hanwen zhang Yiwen Hu Yuhongyang Xue Chuang Liu School of Electrical Engineering and Automation Harbin Institute of TechnologyHarbin 150001China School of Electrical Engineering Northeast Electric Power UniversityJilin 132012China 不详

A hybrid bidirectional DC/DC converter(BDC)is proposed as the fundamental DC/DC module in solid-state transformers,which combines a bidirectional LLC converter and a dual-active-bridge(DAB)*** with a mutual control scheme,both parts of this hybrid BDC can be unified into an interdependent *** this hybrid BDC,the LLC converter supports the output voltage and improves stability by working at the resonant frequency mode and the DAB converter enhances the BDC power capability by controlling the LLC output current *** BDC can achieve the full-load-range soft switching of all active switches by designing the auxiliary inductor of LLC and the minimum output current of *** comparing to the single DAB,the proposed BDC has the higher phase and gain margin which means the BDC improved the relative stability based on Nyquist *** solve the bidirectional power control problem,a dead-band voltage control logic is adopted which can determine the BDC’s power direction based on the output voltage change.A 200 V experimental system has verified the aforementioned features and functions of the BDC.

关键词： Bidirectional DC-DC converter mutual control

Seismogenic tectonics of the Qian-Gorlos earthquake in Jilin Province,China

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Earthquake Science 2016年第2期29卷 93-103页

作者： Jun Shen Bo Shao Xiao-hui Yu Yang Yu Gao Qi Mei Deng hanwen zhang Institute of Disaster Prevention Langfang 065201China Institute of Geology China Earthquake AdministrationBeijing 100029China Lanzhou Institute of Seismology China Earthquake AdministrationLanzhou 730000China

The Qian-Gorlos earthquake, which occurred in the Songliao basin in Jilin Province in 1119 AD, was the largest earthquake to occur in NE China before the 1975 Haicheng earthquake. Based on historical records and surface geological investigations, it has been suggested previously that the earthquake epicenter was in the Longkeng area. However, other workers have considered the epicenter to be in the Halamaodu area based on the landslides and faults found in this region. No seismogenic structure has yet been found in either of these two *** tried to detect active faults in the urban areas of Songyuan City, where the historical earthquake was probably located. One of the aims of this work was to clarify the seismogenic structure so that the seismic risk in the city could be more accurately evaluated. The area was investigated and analyzed using information from remote sensing and topographic surveys, seismic data from petroleum exploration, shallow seismic profiles, exploratory geological trenches on fault outcrops, and borehole data. The geophysical data did not reveal any evidence of faults cutting through Cretaceous or later strata under the Longkeng scarp, which has been suggested to be structural evidence of the Qian-Gorlos earthquake. The continuous fault surfaces on the back edge of terraces in theHalamaodu area stretch for [3.5 km and were probably formed by tectonic activity. However, results from shallow seismic profiles showed that the faults did not extend downward, with the corresponding deep structure being identified as a gentle kink band. A new reverse fault was found to the west of the two suggested epicenters, which presented as a curvilinear fault extending to the west, and was formed by two groups of NE- and NW-trending faults intersecting the Gudian fault. Three-dimensional seismic and shallow seismic data from petroleum exploration revealed its distinct spatial distribution and showed that the fault may cut through Late Quaternary strata. E

关键词： Qian-Gorlos earthquake Historical earthquake Seismogenic structure

Fucoidan antagonizes diet-induced obesity and inflammation in mice

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The Journal of Biomedical Research 2021年第3期35卷 197-205页

作者： Lei Wang Kun zhang Xin Ding Yan Wang Hui Bai Qing Yang Jingjing Ben hanwen zhang Xiaoyu Li Qi Chen Xudong Zhu Key Laboratory of Targeted Intervention of Cardiovascular Disease Collaborative Innovation Center for Cardiovascular Disease Translational MedicineNanjing Medical UniversityNanjingJiangsu 211166China

Obesity is an escalating global pandemic posing a serious threat to human *** intervention therapy using weight-reducing drugs,accompanied by lifestyle modification,is a strategy for the treatment of *** the present study,we explored the role of fucoidan,a seaweed compound,on high-fat diet(HFD)-induced obesity in *** found that fucoidan treatment significantly reduced the body fat and caused redistribution of visceral and subcutaneous fat in HFD-fed ***,fucoidan treatment inhibited adipocyte hypertrophy and inflammation in adipose ***,these results suggest that fucoidan may be a promising treatment for obesity and obesity-induced complications.

关键词： obesity adipose tissue fucoidan inflammation

The Palestine-Israel Issue in the Post-Covid-19 Era—From the Perspective of Neocolonialism

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Asian Journal of Middle Eastern and Islamic Studies 2021年第4期15卷 505-518页

作者： Meng Shu Yun Song hanwen zhang Middle East Studies Institute Shanghai International Studies UniversityShanghaiChina

Strictly speaking,the economic relationship between Israel and Palestine cannot be simply defined as neocolonial occupation,but are closely related to neo-colonialism,in terms of control,dependence,resistance,exploitation,monopoly and ***,neo-colonialism can be used as a perspective to analyse the economic relations between Palestine and *** the two sides have always been in a relatively hostile relationship,due to years of stalemate and Israeli economic control,the two sides have formed an interdependent economic relationship,where Israel has a relatively dominant position in the relations,thanks to its long-term occupation and control over the land,while the Palestinian economy will continue to remain highly dependent on Israel,despite its official efforts to achieve economic *** this case,Israel is reluctant to sever the relationship,and Palestine is unable to decouple from the Israeli *** outbreak of the Covid-19 pandemic has made the prospects for Palestinian-Israeli peace talks even *** the peace process continues to stall,a settlement to resolve the dispute between Israel and the Palestinians remains highly unlikely.

关键词： Economic control Covid-19 pandemic Palestine Israel