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Thermal Characteristics of Air-Water Spray Impingement Cooling of Hot Metallic Surface under Controlled Parametric Conditions

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Journal of Thermal Science 2016年第3期25卷 266-272页

作者： Santosh Kumar Nayak Purna Chandra Mishra school of mechanical engineering KIIT University

Experimental results on the thermal characteristics of air-water spray impingement cooling of hot metallic surface are presented and discussed in this *** controlling input parameters investigated were the combined air and water pressures,plate thickness,water flow rate,nozzle height from the target surface and initial temperature of the hot *** effects of these input parameters on the important thermal characteristics such as heat transfer rate,heat transfer coefficient and wetting front movement were measured and *** flat plate samples of mild steel with dimension 120 mm in length,120 mm breadth and thickness of 4 mm,6 mm,and 8mm respectively were *** air assisted water spray was found to be an effective cooling media and method to achieve very high heat transfer rate from the *** heat transfer rate and heat transfer coefficients were obtained for the lesser i.e,4 mm thick *** in the nozzle height reduced the heat transfer efficiency of spray *** an inlet water pressure of 4 bar and air pressure of 3 bar,maximum cooling rates670℃/s and average cooling rate of 305.23℃/s were achieved for a temperature of 850℃ of the steel plate.

关键词： air-water spray transient temperature cooling rate plate thickness

Overview of Rubik's Cube and Reflections on Its Application in Mechanism

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Chinese Journal of mechanical engineering 2018年第4期31卷 9-20页

作者： Da-Xing Zeng Ming Li Juan-Juan Wang Yu-Lei Hou Wen-Juan Lu Zhen Huang school of mechanical engineering Yanshan University

Rubik’s Cube is a widely popular mechanical puzzle that has attracted attention around the world because of its unique characteristics. As a classic brain-training toy well known to the public, Rubik’s Cube was used for scientific research and technology development by many scholars. This paper provides a basic understanding of the Rubik’s Cube and shows its mechanical art from the aspects of origin and development, characteristics, research status and especially its mechanical engineering design, as well as making a vision for the application in mechanism. First, the invention and origin of Rubik’s Cube are presented, and then the special characteristics of the cube itself are *** that, the present researches of Rubik’s Cube are reviewed in various disciplines at home and abroad, including the researches of Rubik’s Cube scientific metaphors, reduction algorithms, characteristic applications, and mechanism issues. Finally, the applications and prospects of Rubik’s Cube in the field of mechanism are discussed.

关键词： Rubik's Cube Scientific research mechanical art Application and prospects

Theoretical model of biomacromolecule through nanopore including effects of electrolyte and excluded volume

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Applied Mathematics and Mechanics(English Edition) 2016年第6期37卷 787-802页

作者： Chibin ZHANG Xiaohui LIN Hao YANG school of mechanical engineering Southeast University

A theoretical model for the translocation process of biomacromolecule is developed based on the self-consistent field theory （SCFT）, where the biomacromolecule is regarded as a self-avoiding polymer chain actuated by the external potential. In this theoretical model, the external potential, the Coulomb electrostatic potential of the charged ions （the electrolyte effect）, and the attractive interaction between the polymer and the nanopore （the excluded volume effect） are all considered, which have effects on the free energy landscape and conformation entropy during the translocation stage. The result shows that the entropy barrier of the polymer in the solution with high valence electrolyte is much larger than that with low valence electrolyte under the same condition, leading to that the translocation time of the DNA molecules in the solution increases when the valence electrolyte increases. In addition, the attractive interaction between the polymer and the nanopore increases the free energy of the polymer, which means that the probability of the translocation through the nanopore increases. The average translocation time decreases when the excluded volume effect parameter increases. The electrolyte effect can prolong the average translocation time. The simulation results agree well with the available experimental results.

关键词： polymer through nanopore electrolyte effect excluded volume effect freeenergy conformation entropy

dynamic simulation and efficiency analysis of beam pumping system

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Journal of Central South University 2015年第9期22卷 3367-3379页

作者：邢明明董世民童志雄田然凤陈慧玲 school of mechanical engineering Yanshan University

An improved whole model of beam pumping system was built. In the detail, for surface transmission system(STS), a new mathematical model was established considering the influence of some factors on the STS's torsional vibration, such as the time variation characteristic of equivalent stiffness of belt and equivalent rotational inertia of crank. For the sucker rod string(SRS), an improved mathematical model was built considering the influence of some parameters on the SRS's longitudinal vibration, such as the nonlinear friction of plunger, hydraulic loss of pump and clearance leakage. The dynamic response and system efficiency of whole system were analyzed. The results show that there is a jumping phenomenon in the amplitude frequency curve, and the system efficiency is sensitive to motor power, pump diameter, stroke number, ratio of gas and oil, and submergence depth. The simulation results have important significance for improving the efficiency of beam pumping system.

关键词： beam pumping system surface transmission system(STS) sucker rod string(SRS) system efficiency dynamic simulation

Correlation failure analysis of an uncertain hysteretic vibration system

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Earthquake engineering and engineering Vibration 2008年第1期7卷 57-65页

作者：张旭方张义民郝秋菊 school of mechanical engineering Northeastern University

In this paper, a numerical method for correlation sensitivity analysis of a nonlinear random vibration system is presented. Based on the first passage failure model, the probability perturbation method is employed to determine the statistical characteristics of failure modes and the correlation between them. The sensitivity of correlation between failure modes with respect to random parameters characterizing the uncertainty of the hysteretic loop is discussed. In a numerical example, a two-DOF shear structure with uncertain hysteretic restoring force is considered. The statistical characteristics of response, failure modes and the sensitivity of random hysteretic loop parameters are provided, and also compared with a Monte Carlo simulation.

关键词： correlated failure modes uncertain hysteretic loop parameter sensitivity analysis nonlinear randomvibration first passage failure model Monte Carlo simulation

Response Sensitivity to Design Parameters of RV Reducer

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Chinese Journal of mechanical engineering 2018年第3期31卷 115-127页

作者： Yu-Hu Yang Chuan Chen Shi-Yu Wang school of mechanical engineering Tianjin University

dynamic characteristic significantly a ects performance of RV reducer. The current researches mainly pay attention to free vibration properties of RV reducer. In order to satisfy the increasing demand on high performance,response sensi?tivity is analytically studied on the basis of cyclic symmetry structure. Based on the structure characteristics,a dynamic model is developed by taking into account the influence of bearing sti ness,crankshaft bending sti ness and mesh sti ness within planetary and cycloidal stages. For the model,governing equation of motion is derived and solved by Fourier series method. The solution revealed that forced vibrations at primary frequency are well defined structural. There exist three typical forced vibration modes: rotational,translational and planetary component modes. Response sensitivity to basic design parameters is obtained as closed?form expressions by di erential method. With the typical vibration modes,response sensitivity is simplified and classified into three types. Calculation of sensitivity implies that vibrations of the output wheel are sensitive to eccentricity. As eccentricity increases,sensitivity of translation decreases first and then increases,but sensitivity of rotation always increases. The proposed method for analyzing response sensi?tivity provides some principles for selecting parameters for RV reducer from the point of view of forced vibration.

关键词： RV reducer Mesh phasing Vibration modes Sensitivity

Numerical study on the heat dissipation characteristics of high-power LED module

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Science China(Technological Sciences) 2013年第9期56卷 2150-2155页

作者： LEE DaeWoo CHO Sung-Wook KIM Youn-Jea Graduate school of mechanical engineering Sungkyunkwan University school of mechanical engineering Sungkyunkwan University

LED lighting has problems such as short life span, power reduction due to the LED chip's heat, and decreased luminance efficiency etc. Many studies on the optimization of the thermal performance of LEDs have been conducted actively to solve these problems. The present study changes the fin shape and intervals of various heat sink designs so that LED can effectively produce a thermal effect. The water-cooling heat release system and the heat pipe methods show higher thermal performance results than the existing systems; however, the system is of high cost and requires a large-scale apparatus. This study carried out a numerical analysis of the thermal control system by applying heat flux and heat sink properties as an active heat release system using the commercial code ANSYS ver. 13.0 and verified the validity of the new heat sink design for temperature distribution analysis.

关键词： LED lighting water-cooling heat release system heat loss

Stability in Probability and Inverse Optimal Control of Evolution Systems Driven by Levy Processes

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IEEE/CAA Journal of Automatica Sinica 2020年第2期7卷 405-419页

作者： Khac Duc Do school of Civil and mechanical engineering CurtinUniversity

This paper first develops a Lyapunov-type theorem to study global well-posedness(existence and uniqueness of the strong variational solution)and asymptotic stability in probability of nonlinear stochastic evolution systems(SESs)driven by a special class of Levy processes,which consist of Wiener and compensated Poisson *** theorem is then utilized to develop an approach to solve an inverse optimal stabilization problem for SESs driven by Levy *** inverse optimal control design achieves global well-posedness and global asymptotic stability of the closed-loop system,and minimizes a meaningful cost functional that penalizes both states and *** approach does not require to solve a Hamilton-Jacobi-Bellman equation(HJBE).An optimal stabilization of the evolution of the frequency of a certain genetic character from the population is included to illustrate the theoretical developments.

关键词： Evolution system inverse optimal control Levy processes stability in probability well-posedness

Biomimetic Shoulder Complex Based on 3-PSS/S Spherical Parallel Mechanism

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Chinese Journal of mechanical engineering 2015年第1期28卷 29-37页

作者： HOU Yulei HU Xinzhe ZENG Daxing ZHOU Yulin school of mechanical engineering Yanshan University

The application of the parallel mechanism is still limited in the humanoid robot fields, and the existing parallel humanoid robot joint has not yet been reflected the characteristics of the parallel mechanism completely, also failed to solve the problem, such as small workspace, effectively. From the structural and functional bionic point of view, a three degrees of freedom（DOFs） spherical parallel mechanism for the shoulder complex of the humanoid robot is presented. According to the structure and kinetic characteristics analysis of the human shoulder complex, 3-PSS/S（P for prismatic pair, S for spherical pair） is chosen as the original configuration for the shouder complex. Using genetic algorithm, the optimization of the 3-PSS/S spherical parallel mechanism is performed, and the orientation workspace of the prototype mechanism is enlarged obviously. Combining the practical structure characteristics of the human shouder complex, an offset output mode, which means the output rod of the mechanism turn to any direction at the point a certain distance from the rotation center of the mechanism, is put forward, which provide possibility for the consistent of the workspace of the mechanism and the actual motion space of the human body shoulder joint. The relationship of the attitude angles between different coordinate system is derived, which establishs the foundation for the motion descriptions under different conditions and control development. The 3-PSS/S spherical parallel mechanism is proposed for the shoulder complex, and the consistence of the workspace of the mechanism and the human shoulder complex is realized by the stuctural parameter optimization and the offset output design.

关键词： shoulder complex biomimetics spherical parallel mechanism