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低温地板辐射供暖系统的供冷研究

山东建筑工程学院学报 2003年第3期18卷 55-57,71页

作者：李清清刁乃仁山东建筑工程学院空调工程系山东济南250014

建立了地板辐射供暖供冷系统的稳态传热模型,通过数值求解,给出了理论计算结果,并结合实验数据,分析了供水温度、室内设计温度、管间距、埋管深度等因素对热流密度的影响,为系统两联供提供了初步估算依据。结果表明:其它条件一定时,热... 详细信息

建立了地板辐射供暖供冷系统的稳态传热模型,通过数值求解,给出了理论计算结果,并结合实验数据,分析了供水温度、室内设计温度、管间距、埋管深度等因素对热流密度的影响,为系统两联供提供了初步估算依据。结果表明:其它条件一定时,热流密度随管间距呈线性变化;随埋管深度呈非线性变化;管间距过大和埋管过深不利于系统两联供的实现,建议管间距在200mm之内,埋管深度60mm左右。

关键词：地板辐射供暖辐射供冷供暖系统两联供热流密度

On the consistency of two-phase local/nonlocal piezoelectric integral model

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Applied Mathematics and Mechanics(English Edition) 2021年第11期42卷 1581-1598页

作者： Yanming ren Hai qing State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

In this paper,we propose general strain-and stress-driven two-phase local/nonlocal piezoelectric integral models,which can distinguish the difference of nonlocal effects on the elastic and piezoelectric behaviors of *** nonlocal piezoelectric model is transformed from integral to an equivalent differential form with four constitutive boundary conditions due to the difficulty in solving intergro-differential equations *** nonlocal piezoelectric integral models are used to model the static bending of the Euler-Bernoulli piezoelectric beam on the assumption that the nonlocal elastic and piezoelectric parameters are coincident with each *** governing differential equations as well as constitutive and standard boundary conditions are *** is found that purely strain-and stress-driven nonlocal piezoelectric integral models are ill-posed,because the total number of differential orders for governing equations is less than that of boundary ***,the traditional nonlocal piezoelectric differential model would lead to inconsistent bending response for Euler-Bernoulli piezoelectric beam under different boundary and loading *** nominal variables are introduced to normalize the governing equations and boundary conditions,and the general differential quadrature method(GDQM)is used to obtain the numerical *** results from current models are validated against results in the *** is clearly established that a consistent softening and toughening effects can be obtained for static bending of the Euler-Bernoulli beam based on the general strain-and stress-driven local/nonlocal piezoelectric integral models,respectively.

关键词： nonlocal piezoelectric integral model softening effect toughening effect general differential quadrature method(GDQM)

Modelling ignition probability with pairwise mixing-reaction model for flame particle tracking

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Chinese Journal of Aeronautics 2021年第5期34卷 523-534页

作者： qing XIE Zhuyin ren Ke WANG School of Aerospace Engineering Tsinghua UniversityBeijing 100084China Institute for Aero Engine Tsinghua UniversityBeijing 100084China Aero Engine Academy of China Beijing 101300China

Reduced order models for ignition analysis can offer insights into ignition processes and facilitate the combustor *** this study,a Pairwise Mixing-Reaction(PMR)model is formulated to model the interaction between the flame particle and the surrounding cell mixture during Lagrangian flame particle ***,the model accounts for the two-way coupling of mass and energy between the flame particle and the surrounding shell layer by modelling the corresponding turbulent mixing,chemical reaction and evaporation process if *** state of a flame particle,e.g.,burnt,hot gas or extinguished,is determined based on particle *** model can properly describe the ignition process with a spark kernel being initiated in a nonflammable region,which is of practical importance in certain turbine engines and has not been rigorously accounted for by the existing models based on the estimation of local Karlovitz *** model is integrated into an ignition probability analysis platform and is demonstrated for a methane/air bluff-body flame with the flow and fuel/air mixing characteristics being extracted from a non-reacting *** results show that for the spark location being at the extreme fuellean outer shear layer of the recirculation zone,PMR can yield ignition events with a significant number of active flame *** mechanisms for the survival of the initial flame particles and the entrainment of the survived flame particles into the recirculation zone are *** results also show that the ignition probability map from PMR agrees well with the experimental observation:a high ignition probability in the shear layer of the recirculation zone near the mean stoichiometric surface,and low ignition probabilities inside the recirculation zone and the top stagnation region of the recirculation *** parametric study shows that the predicted shape of the ignition progress factor and ignition probability is in general inse

关键词： Bluff-body stabilized flame Igniting process Ignition probability Lagrangian particle tracking Pairwise mixing-reaction

On Optimal Mean-Field Control Problem of Mean-Field Forward-Backward Stochastic System with Jumps Under Partial Information

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Journal of Systems Science & Complexity 2017年第4期30卷 828-856页

作者： ZHOU qing ren Yong WU Weixing School of Science Beijing University of Posts and Telecommunications Department of Mathematics Anhui Normal University Research Center of Applied Finance and School of Finance and Banking University of International Business and Economics

This paper considers the problem of partially observed optimal control for forward-backward stochastic systems driven by Brownian motions and an independent Poisson random measure with a feature that the cost functional is of mean-field type. When the coefficients of the system and the objective performance functionals are allowed to be random, possibly non-Markovian, Malliavin calculus is employed to derive a maximum principle for the optimal control of such a system where the adjoint process is explicitly expressed. The authors also investigate the mean-field type optimal control problem for the system driven by mean-field type forward-backward stochastic differential equations(FBSDEs in short) with jumps, where the coefficients contain not only the state process but also its expectation under partially observed information. The maximum principle is established using convex variational technique. An example is given to illustrate the obtained results.

关键词： Forward-backward stochastic differential equation Girsanov's theorem jump diffusion Malliavin calculus maximum principle mean-field type partial information.

Optimal Parallel Algorithm for the Knapsack Problem Without Memory Conflicts

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Journal of Computer Science & Technology 2004年第6期19卷 760-768页

作者： Ken-LiLi ren-FaLi qing-HuaLi SchoolofComputerandCommunication HunanUniversityChangsha410082P.R.China SchoolofComputerScienceandTechnology HuazhongUniversityofScienceandTechnologyWuhan430074P.R.China

The knapsack problem is well known to be NP-complete. Due to its importance in cryptosystem and in number theory, in the past two decades, much effort has been made in order to find techniques that could lead to practical algorithms with reasonable running time. This paper proposes a new parallel algorithm for the knapsack problem where the optimal merging algorithm is adopted. The proposed algorithm is based on anEREW-SIMD machine with shared memory. It is proved that the proposed algorithm is both optimal and the first without memory conflicts algorithm for the knapsack problem. The comparisons of algorithm performance show that it is an improvement over the past researches. Keywords knapsack problem - NP-complete - parallel algorithm - optimal algorithm - memory conflict Supported by the National Natural Science Foundation of China under Grant No.60273075, the National High Technology Development 863 Program of China under Grant No.863-306-ZD-11-01-06.Ken-Li Li received his B.S. and M.S. degrees in mathematics from National University of Defense Technology and Central South University in 1995 and 2000 respectively and he is now a Ph.D. candidate in computer software and theory at Huazhong University of Science and Technology. His main research interests include parallel computing and combinatorial optimization.ren-Fa Li received his Ph.D. degree in computer software and theory at Huazhong University of Science and Technology, and he is concurrently a professor and Ph.D. supervisor in School of Computer and Communication, Human University. His main research interests include network computing.qing-Hua Li received his M.S. degree in computer science from Huazhong University of Science and Technology in 1981, and he is concurrently a professor and Ph.D. supervisor in School of Computer Science and Technology, Huazhong University of Science and Technology. His current research interests include parallel processing, combinatorial optimization, and grid comp

关键词： knapsack problem NP-complete parallel algorithm optimal algorithm memory conflict

Influence of texture distribution in magnesium welds on their non-uniform mechanical behavior:A CPFEM study

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Journal of Materials Science & Technology 2020年第11期42卷 168-176页

作者： Weijie ren Dejia Liu qing Liu renlong Xin Joint International Laboratory for Light Alloys(MOE) College of Materials Science and EngineeringChongqing UniversityChongqing 400044China College of Materials Science and Engineering East China Jiaotong UniversityNanchang3300J3China Key Laboratory for Light-weight Materials NanjingTech UniversityNanjing211816China

Recent studies indicate that the texture distribution in friction stir welded(FSW)Mg alloys can be tailored and hence improve the joint *** this work,a crystal plasticity finite element modeling(CPFEM)was performed to understand the effects of texture distribution in stir zone(SZ)on the nonuniform plastic deformation and fracture *** total,six kinds of observed or purposely tilted texture distributions were ***"concave-convex"appearance,as commonly observed in the tensile sample,was successfully *** reveals that the mirror-symmetrical distribution of basal planes in the region of easy to activate basal slip(EABS)determined the"concave-convex"appearance in *** asymmetrical appearance exchanged on plane A and plane B when the directions of basal planes were switched in the two EABS ***,the asymmetrical feature of plastic deformation was changed with varying the texture distribution in ***"embossed"feature became more obvious in SZ-center first,and then gradually weakened with the c-axis rotated away from the weld plate *** necking was successfully simulated in SZ-center of FSW-H joint and in SZ-side of FSW-L *** might determine the observed fracture *** believe that this simulation study is helpful for further improving the performance of FSW Mg joints.

关键词： Friction stir welding Magnesium alloy CPFEM Non-uniform deformation Fracture

Description of N=7～9 Isotones with a Modified Single-Particle Potential

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Communications in Theoretical Physics 2008年第12期50卷 1396-1400页

作者： GUO Yan-qing ren Zhong-Zhou CHEN Yu-qing Department of Physics Nanjing University Nanjing 210008 China Center of Theoretical Nuclear Physics National Laboratory of Heavy-Ion Accelerator Lanzhou 730000 China Joint Center for Particle Nuclear Physics and Cosmology Nanjing 210008 China Department of Physics and Electronic Engineering Hanshan Normal University Chaozhou 521041 China

We study the level structures of N = 7 - 9 isotones and their mirror nuclei in the framework of the single-particle potential model. Considering the limitation of the conventional potential-model calculation, the isospindependent 12 coupling is newly introduced in the average potential. The modified model gives a unified description for the structures of all studied nuclei. Galculations self-consistently produce the s-d level inversion in N = 9 isotones and their mirror nuclei. Meanwhile, the s-p level inversion in the mirror nuclei ^11Be and ^11N is reproduced. The study confirms the neutron halo structures in ^11Be（2s1/2）, ^11Be（1p1/2）, ^12B（2s1/2）, ^14B（2s1/2）, ^13C（2sl/2）, ^15C（2s1/2） and the proton halo structure in ^17F（2s1/2）. The agreement between theory and experiment indicates that the inclusion of the i2 coupling is a feasible way to explain the abnormal structures of exotic light nuclei.

关键词： modified single-particle potential level inversion l^2 coupling

Fixed-point ICA algorithm for blind separation of complex mixtures containing both circular and noncircular sources

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The Journal of China Universities of Posts and Telecommunications 2016年第2期23卷 15-23页

作者： Yao Junliang ren Haipeng Liu qing School of Automation and Information Engineering Xi'an University of Technology

Fixed-point algorithms are widely used for independent component analysis（ICA） owing to its good convergence. However, most existing complex fixed-point ICA algorithms are limited to the case of circular sources and result in phase ambiguity, that restrict the practical applications of ICA. To solve these problems, this paper proposes a two-stage fixed-point ICA（TS-FPICA） algorithm which considers complex signal model. In this algorithm, the complex signal model is converted into a new real signal model by utilizing the circular coefficients contained in the pseudo-covariance matrix. The algorithm is thus valid to noncircular sources. Moreover, the ICA problem under the new model is formulated as a constrained optimization problem, and the real fixed-point iteration is employed to solve it. In this way, the phase ambiguity resulted by the complex ICA is avoided. The computational complexity and convergence property of TS-FPICA are both analyzed theoretically. Simulation results show that the proposed algorithm has better separation performance and without phase ambiguity in separated signals compared with other algorithms. TS-FPICA convergences nearly fast as the other fixed-point algorithms, but far faster than the joint diagonalization method, e.g. joint approximate diagonalization of eigenmatrices（JADE）.

关键词： ICA fixed-point iteration noncircular complex signal phase ambiguity

Silicon carbide waste as a source of mixture materials for cement mortar

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Frontiers of Environmental Science & Engineering 2017年第5期11卷 47-54页

作者： Zhengwu Jiang Qiang ren Haoxin Li qing Chen Key Laboratory of Advanced Civil Engineering Materials Ministry of Education Tongji University Shanghai 201804 China

This paper presents an investigation of the feasibility of recycling silicon carbide waste （SCW） as a source of mixture materials in the production of cement mortar. Mortars with SCW were prepared by replacing different amounts of cement with SCW, and the properties of the resulting mortars, such as the fluidity, strength and shrinkage, were studied in this work. Thermogravimetry-differential scanning calorimet;＇y and scanning electron microscopy were employed to understand the reasons for the property changes of the mortars. The results indicate that SCW decreases the initial and l-h fluidity of fresh mortar but improves the loss of fluidity. The mortar with SCW exhibits a lower strength at 3 d and7 d but a higher strength at 28 d and 56 d compared to the control. The shrinkage rate of cement mortar with SCW shows an obvious decrease as the replacement ratio increases. In addition, the content of calcium hydroxide in hardened paste also shows that SCW has some impact on the hydration of the cement-SCW system. The microstructures of the hardened paste also show evidence for a later strength change of mortar containing SCW. This work provides a strategic reference for possibly applying SCW as a mixture material in the production of cement mortar.

关键词： Silicon carbide waste Cement mortar Fluidity Strength Shrinkage