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Strain Rate Effect of AE Characteristics in the Whole Process of Uniaxial Tensile of Mortar

Journal of Wuhan University of Technology(Materials Science) 2023年第3期38卷 547-556页

作者：王娜王岩 SU Yihui ZHAO Haitao college of Civil Engineering and Transportation Hohai UniversityNanjing 210024China

We completed the uniaxial tensile test of mortar in the range of strain rate from 10^(-6)to 10^(-4)s^(-1)in the section containing softening,and carried out acoustic emission monitoring(AE)simultaneously.A series of AE parameters and spectrum analysis methods were used to identify the damage evolution process and cracking mechanism of mortar at different strain *** results show that,with the increase of strain rate,the peak stress and tensile elastic modulus of mortar increase obviously,and the stress level corresponding to the starting point of AE activity increases significantly as well,which indicates that the mechanical properties and AE characteristics of mortar have obvious strain rate *** the increase of strain rate,the cumulative AE hit decreases gradually,while the average AE hit rate increases significantly,indicating that the increase of strain rate reduces the damage degree of internal microstructure of the specimen,but the crack propagation speed *** the pre-peak stress stage,the average of AE ringing count and signal energy decreases with the increase of strain rate,while the average of duration increases;in the post-peak stress stage(f_(t)-30%f_(t)),the average of the three AE parameters all increase with the increase of strain rate,indicating that the strain rate effect on the damage process of mortar is different before and after peak stress,and the damage mechanism represented by different parameters is also *** the whole process of uniaxial tensile of mortar,with the increase of strain rate,the scatter distribution of AE frequency-amplitude becomes more discrete,and the b-value shows a decreasing *** addition,the average level of AE peak frequency decreases with the increase of strain rate,while that of ca8 band wavelet energy spectrum coefficient *** is indicated that the increase of strain rate enables the crack propagation state of mortar specimen to become unstable,and the width of macrocrack incre

关键词： mortar acoustic emission uniaxial tension strain rate

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Form Invariance and Conserved Quantity for Non-holonomic Systems with Variable Mass and Unilateral Constraints

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Communications in Theoretical Physics 2007年第2期47卷 213-216页

作者： WANG Jing LI Yuan-Cheng HOU Qi-Bao XIA Li-Li college of Physical Science and Technology University of Petroleum China Dongying 257061 China

The paper studies the form invariance and a type of non-Noether conserved quantity called Mei conserved quantity for non-holonomic systems with variable mass and unilateral constraints. Acoording to the invariance of the form of differential equations of motion under infinitesimal transformations, this paper gives the definition and criterion of the form invariance for non-holonomic systems with variable mass and unilateral constraints. The condition under which a form invariance can lead to Mei conservation quantity and the form of the conservation quantity are deduced. An example is given to illustrate the application of the results.

关键词： variable mass unilateral constraint non-holonomic system form invaxiance conserved quantity

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SAMES： deadline-constraint scheduling in MapReduce

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Frontiers of Computer Science 2015年第1期9卷 128-141页

作者： Xite WANG Derong SHEN Mei BAI Tiezheng NIE Yue KOU Ge YU college of Information Science & Engineering Northeastern University Shenyang 110819 China

MapReduce is a popular parallel data-processing system, and task scheduling is one of the kernel techniques in MapReduce. In many applications, users have requirements that their MapReduce jobs should be completed before specific deadlines. Hence, in this paper, a novel scheduling algorithm based on the most effective sequence （SAMES） is proposed for deadline-constraint jobs in MapReduce. First, according to the characteristics of MapReduce, we propose a novel sequence-based execution strategy for MapReduce jobs and a new concept, the effective sequence （ES）. Then, we design some efficient approaches for finding ESes and choose the most effective sequence （MES） for job execution. We also propose methods for MES-updates and exception handling. Finally, we verify the effectiveness of SAMES through experiments. The experimental results show that SAMES is an efficient scheduling algorithm for deadline-constraint jobs in MapReduce.

关键词： MapReduce scheduling deadline

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Hybrid CuO-Co_(3)O_(4)nanosphere/RGO sandwiched composites as anode materials for lithium-ion batteries

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Chinese Journal of Chemical Engineering 2022年第7期35卷 185-192页

作者： Yingmeng Zhang Luting Liu Qingwei Deng Wanlin Wu Yongliang Li Xiangzhong Ren Peixin Zhang Lingna Sun college of Chemistry and Environmental Engineering Shenzhen UniversityShenzhen 518060China

Hybrid CuO-Co_(3)O_(4)nanosphere building blocks have been embedded between the layered nanosheets of reduced graphene oxides with a three dimensional(3D)hybrid architecture(CuO-Co_(3)O_(4)-RGO),which are successfully applied as enhanced anodes for lithium-ion batteries(LIBs).The CuO-Co_(3)O_(4)-RGO sandwiched nanostructures exhibit a reversible capacity of~847 mA·h·g^(-1)after 200 cycles’cycling at 100 mA·g^(-1)with a capacity retention of 79%.The CuO-Co_(3)O_(4)-RGO compounds show superior electrochemical properties than the comparative CuO-Co_(3)O_(4),Co_(3)O_(4)and CuO anodes,which may be ascribed to the following reasons:the hybridizing multicomponent can probably give the complementary advantages;the mutual benefit of uniformly distributing nanospheres across the layered RGO nanosheets can avoid the agglomeration of both the RGO nanosheets and the CuO-Co_(3)O_(4) nanospheres;the 3D storage structure as well as the graphene wrapped composite could enhance the electrical conductivity and reduce volume expansion effect associated with the discharge-charge process.

关键词： Composites Nanostructure Nanoparticles Reduced graphene oxide Metal oxides Lithium ion batteries

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Research on the explosion characteristics of chlorine dioxide gas

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Chinese Chemical Letters 2008年第11期19卷 1375-1378页

作者： Ri Ya Jin Shuang Qi Hu Ying Hao Zhang Tao Bo college of Chemical ＆ Environmental Engineering North University of China Taiyuan 030051 China

The explosion characteristics of chlorine dioxide gas have been studied for the first time in a cylindrical exploder with a shell capacity of 201. The experimental results have indicated that the lower concentration limit for the explosive decomposition of chlorine dioxide gas is 9.5% （[ClO2]/[air]）, whereas there is no corresponding upper concentration limit. The maximum pressure of explosion relative to the initial pressure was measured as 0.024 MPa at 10% ClO2 and 0.641 MPa at 90% ClO2. The induction time （the time from the moment of sparking to explosion） at 10% ClO2 was 2195 ms, but at 90% ClO2 the induction time was just 8 ms. The explosion reaction mechanism of ClO2 is of a degenerate chain-branching type involving the formation of a stable intermediate （Cl2O3）, from which the chain branching occurs.

关键词： Chlorine dioxide gas Explosive decomposition Pressure of explosion Explosion limit

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Lie-Form Invariance of a Type of Non-holonomic Singular Systems

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Communications in Theoretical Physics 2007年第3期47卷 409-412页

作者： WANG Jing LI Yuan-Cheng HOU Qi-Bao XIA Li-Li college of Physical Science and Technology China University of Petroleum Dongying 257061 China

In this paper, the Lie-form invariance of a type of non-holonomic singular systems is studied. The differential equations of motion of the systems are given. The definition and the criterions of the Lie-form invariance for the systems are presented. The Hojman conserved quantity and the Mei conserved quantity are obtained. An example is given to illustrate the application of the results.

关键词： non-holonomic constraint singular system symmetry conserved quantity

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Direct methanol fuel cells system-A review of dual-role electrocatalysts for oxygen reduction and methanol oxidation

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Journal of Materials Science & Technology 2022年第19期114卷 29-41页

作者： Yuanhui Zuo Wenchao Sheng Wenquan Tao Zhuo Li college of Environment Science and Engineering Tongji UniversityShanghai 200092China

One fundamental challenge in exploiting direct methanol fuel cells(DMFCs)is the preparation of inex-pensive,high active electrocatalysts,which are highly active and durable for the two half-reactions,i.e.,the methanol oxidation reaction(MOR)at the anode and the oxygen reduction reaction(ORR)at the *** group metals-based catalysts have been known the governing dual-functional electro-catalysts based on the literature *** these catalysts are expensive and commercialize the DMFC less *** addition to the high-cost,there are also methanol crossover,CO poisoning,long-term instability,and other problems as for Pt-based *** the dual-role MOR&ORR catalysts,methanol crossover is inevitable to a certain extent on the current development of DMFC with losses in terms of cell *** this regard,one strategy is to exploit high selective anodic/cathodic electrocatalysts to cap-italize the energy density at a high concentration of *** to the summary results,there are mainly two types of dual-role electrocatalysts:one is Pt-support/co-catalyst(designated as P-S/C)for MOR/ORR,the other is catalyst/co-catalyst(designated as C/C)for MOR/*** paper aims to review the design and construction of the various dual-role catalysts and give some discussion briefly.

关键词： DMFC Dual-role Pt-support/co-catalyst Catalyst/co-catalyst MOR/ORR

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Researches on the Structure and Properties of Mullite Solid Solution Made from Industrial Waste

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Chinese Journal of Structural Chemistry 2006年第8期25卷 965-970页

作者： RUAN Yu-Zhong YU Yan WU Ren-Ping college of Materials Science and Engineering Fuzhou University Fuzhou 350002 China

The waste slag from aluminum profile factory and silicon fine powder from ferroalloy factory were utilized as the main raw materials to synthesize mullite solid solution Al4＋2xSi2-xO10-x/2, whose defect formation mechanism, crystalline phase composition, crystal cell parameters, microstructures and morphologies were characterized in detail by XRD and SEM. The results show that because of the ultrafine particle size of the materials, the content of mullite solid solution synthesized by this method is higher than that by regular method. Keywords： waste slag from aluminum factory, silicon fine powder, mullite, solid solution

关键词： waste slag from aluminum factory silicon fine powder mullite solid solution

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Cathodic shift of onset potential on TiO_(2)nanorod arrays with significantly enhanced visible light photoactivity via nitrogen/cobalt co-implantation

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Chinese Physics B 2021年第5期30卷 114-119页

作者： Xianyin Song Hongtao Zhou Changzhong Jiang college of Materials Science and Engineering Hunan UniversityChangsha 410082China

Despite anionic doping has been widely implemented to increase the visible light activity of TiO_(2),it often gives rise to a dramatical anodic shift in current onset ***,we show an effective method to achieve the huge cathodic shift of TiO_(2) photoanode with significantly enhanced visible light photo-electrochemical activity by nitrogen/cobalt *** nitrogen/cobalt co-doped TiO_(2)nanorod arrays(N/Co-TiO_(2))exhibit a cathodic shift of 350 mV in onset potential relative to only nitrogen-doped TiO_(2)(N-TiO_(2)).Moreover,the visible-light(λ>420 nm)photocurrent density of N/Co-TiO_(2) reaches 0.46 mA/cm^(2),far exceeding 0.07 mA/cm^(2) in N-TiO_(2)at 1.23 V versus reversible hydrogen electrode(RHE).Systematic characterization studies demonstrate that the enhanced photo-electrochemical performance can be attributed to the surface synergic sputtering of high-energy nitrogen/cobalt ions.

关键词： ion implantation TiO_(2) surface sputtering photo-electrochemical water splitting

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Adaptive Tracking Control for Output-Constrained Switched MIMO Pure-Feedback Nonlinear Systems with Input Saturation

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Journal of Systems Science & Complexity 2023年第3期36卷 960-984页

作者： ZHANG Haoyan ZHAO Xudong WANG Huanqing NIU Ben XU Ning college of Control Science and Engineering Bohai UniversityJinzhou 121013China Faculty of Electronic Information and Electrical Engineering Dalian University of TechnologyDalian 116024China college of Mathematical Science Bohai UniversityJinzhou 121013China School of Information Science and Engineering Shandong Normal UniversityJinan 250014China college of Information Science and Technology Bohai UniversityJinzhou 121013China

In this paper,an adaptive neural tracking control scheme for a class of uncertain switched multi-input multi-output(MIMO)pure-feedback nonlinear systems is *** considered MIMO pure-feedback nonlinear system contains input and output constraints,completely unknown nonlinear functions and time-varying external *** unknown nonlinear functions representing system uncertainties are identified via radial basis function neural networks(RBFNNs).Then,the Nussbaum function is utilized to deal with the nonlinearity issue caused by the input *** prevent system outputs from violating prescribed constraints,the barrier Lyapunov functions(BLFs)are ***,a switched disturbance observer is designed to make the time-varying external disturbances *** on the backstepping recursive design technique and the Lyapunov stability theory,the developed control method is verified applicable to ensure the boundedness of all signals in the closed-loop system and make the system output track given reference signals ***,a numerical simulation is given to demonstrate the effectiveness of the proposed control method.

关键词： Adaptive control input saturation neural networks output constraints switched MIMO pure-feedback nonlinear systems

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