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| 1 | A review of selective laser melting of aluminum alloys: Processing,microstructure, property and developing trends显示文摘Selective laser melting(SLM) is an attractive rapid prototyping technology for the fabrication of metallic components with complex structure and high performance. Aluminum alloy, one of the most pervasive structural materials, is well known for high specific strength and good corrosion resistance. But the poor laser formability of aluminum alloy restricts its application. There are problems such as limited processable materials, immature process conditions and metallurgical defects on SLM processing aluminum alloys. Some efforts have been made to solve the above problems. This paper discusses the current research status both related to the scientific understanding and technology applications. The paper begins with a brief introduction of basic concepts of aluminum alloys and technology characterization of laser selective melting. In addition, solidification theory of SLM process and formation mechanism of metallurgical defects are discussed. Then, the current research status of microstructure, properties and heat treatment of SLM processing aluminum alloys is systematically reviewed respectively. Lastly, a future outlook is given at the end of this review paper. | Jinliang Zhang Bo Song Qingsong Wei Dave Bourell Yusheng Shi | 2019 | Journal of Materials Science & Technology2019,35,2: | 77 |
| 2 | Mechanism and control of convective heat transfer——Coordination of velocity and heat flow fields显示文摘A second look has been given at the mechanism of convective heat transfer based on the analogy between convection and conduction with heat sources. The strength of convective heat transfer depends not only on the fluid velocity and fluid properties, but also on the coordination of fluid velocity and heat flow fields. Hence, based on the included angle of velocity and temperature gradient vectors, the presence of fluid motion may enhance or reduce heat transfer. With this concept, the known heat transfer phenomena may be understood in a deeper way. More important is that some novel approaches of heat transfer control can be developed. | QUO ZengyuanDepartment of Engineering Mechanics, Tsinghua University, Beijing 100084, China | 2001 | Chinese Science Bulletin2001,46,7: | 60 |
| 3 | Application of entransy dissipation extremum principle in radiative heat transfer optimization显示文摘The concepts of entransy flux and entransy dissipation in radiative heat transfer were introduced based on the analogy with heat conduction and heat convection processes. Entransy will be partially dissipated during the radiative heat transfer processes due to the irreversibility. The extremum principle of entransy dissipation was developed for optimizing radiative heat transfer processes. This principle states that for a fixed boundary temperature the radiative heat transfer is optimized when the entransy dissipation is maximized, while for a fixed boundary heat flux the radiative heat transfer process is optimized when the entransy dissipation is minimized. Finally, examples for the application of the entransy dissipation extre- mum principle are presented. | Jing Wu XinGang Liang | 2008 | Science China(Technological Sciences)2008,51,8: | 56 |
| 4 | Tectonic thermal history and its significance on the formation of oil and gas accumulation and mineral deposit in Ordos Basin显示文摘The analyzing data on stratigraphic temperature measurement , thermal conductivity of the strata and radioactive heat production rate show that the present average geothermal gradient in the Ordos Basin is 2.93℃/100 m, and the average heat flow value is 61.78 mW/m2, which belongs to the mesothermal basin, and the value of the present geothermal gradient and heat flow in the east is higher than that in the west. The sandstone radioactive heat production rate of Zhiluo Group in Dongsheng Uranium deposits of Yimeng uplift is obviously higher in the mudstone, indicating that there exists a uranium anomaly. Based on studies of the present thermal field of the basin, the late-Mesozoic paleotemperature and paleogeothermal gradient are determined by using different kinds of paleotemperature methods. According to the anomaly of the late-Mesozoic paleotemperature gradient and magmatic event age, there was a tectonic thermal event in the early Cretaceous epoch of late-Mesozoic. This article rebuilds tectonic thermal history of different tectonic units by thermal history simulation using basin simulating software. The evolution of oil-gas and coal, and accumulation (mineralization) of mineral uranium are all controlled by the tectonic thermal history in the Ordos basin, especially by the tectonic thermal event that happened in the late Mesozoic. For both the gas source rocks of upper Paleozoic group and lower paleozoic group, the gas was largely generated in the early Cretaceous epoch of the late Mesozoic. The main petroleum generation period for Yanchang Group in Triassic system is the early Cretaceous epoch too, and the highest thermal maturity of the coal of Permo-Carboniferous, Triassic, and Jurassic reaches is the early Cretaceous epoch also. Early Cretaceous epoch is still one of the most important mineralizing periods of uranium. | REN ZhanLi ZHANG Sheng GAO ShengLi CUI JunPing XIAO YuanYuan XIAO Hui | 2007 | Science China Earth Sciences2007,50,z2: | 44 |
| 5 | Metal foams: A survey显示文摘The current state-of-the-art in the development of cellular metal foams is reviewed, with focus on their fabrication, mechanical/thermal/acoustic properties, and potential applications as lightweight panels, energy absorbers, heat exchangers, and acoustic liners. Foam property charts with scaling relations are presented, allowing scoping and selection through the use of material indices. | Michael F.Ashby 卢天健 | 2003 | Science China Chemistry2003,46,6: | 45 |
| 6 | Principle of equipartition of entransy dissipation for heat exchanger design显示文摘In the present work,a principle of equipartition of entransy dissipation(EoED) for heat exchanger design is established,which says that for a heat exchanger design with given heat duty and heat transfer area,the total entransy dissipation rate reaches the minimum when the local entransy dissipation rate is uniformly distributed along the heat exchanger.When the heat transfer coefficient is unfixed,the total entransy dissipation obtained by the EoED principle is less than that obtained by the principle of equipartition of temperature difference(EoTD).Furthermore,the exchanger effectiveness obtained by the EoED principle is larger than that obtained by the EoTD principle.When the heat transfer coefficient is fixed,the EoED principle is equivalent to the EoTD principle.We show that the equipartition of entropy production(EoEP) and EoED principles give rise to difference in entropy generation and entransy dissipation for a heat exchanger optimization design.The discrepancies are caused by distinct features of entropy production minimization and entransy dissipation minimization principles,the former is to optimize the design of heat exchanger by making the lost available work minimum,while the latter is not involved with heat-work conversion.It is found that the entropy generation number is not suitable for evaluating heat exchanger performance,since it directly depends on the inlet and outlet temperatures of working fluids.On the contrary,the entransy dissipation number is not directly related to the inlet and outlet temperatures of working fluids.Therefore,the entransy dissipation number is more suitable for serving as a criterion to evaluate heat exchanger performance. | GUO JiangFeng,XU MingTian & CHENG Lin Institute of Thermal Science and Technology,Shandong University,Jinan 250061,China | 2010 | Science China(Technological Sciences)2010,53,5: | 46 |
| 7 | “Volume-Point” heat conduction constructal optimization with entransy dissipation minimization objective based on rectangular element显示文摘By taking equivalent thermal resistance, which reflects the average heat conduc- tion effect and is defined based on entransy dissipation, as optimization objective, the 'volume to point' constructal problem of how to discharge the heat generated in a fixed volume to a heat sink on the border through relatively high conductive link is re-analyzed and re-optimized in this paper. The constructal shape of the control volume with the best average heat conduction effect is deduced. For the elemental area and the first order construct assembly, when the thermal current density in the high conductive link is linear with the length, the optimized shapes of assemble based on the minimization of entransy dissipation are the same as those based on minimization of maximum temperature difference, and the mean tem- perature difference is 2/3 of the maximum temperature difference. For the second and higher order construct assemblies, the thermal current densities in the high conductive link are not linear with the length, and the optimized shapes of assem- ble based on the minimization of entransy dissipation are different from those based on minimization of maximum temperature difference. For the same parame- ters, the constructs based on minimization of entransy dissipation and the con- structs based on minimization of maximum temperature difference are compared, and the results show that the constructs based on entransy dissipation can de- crease the mean temperature difference better than the constructs based on mini- mization of maximum temperature difference. But with the increase of the number of the order, the mean temperature difference does not always decrease, and there exist some fluctuations. Because the idea of entransy describes the heat transfer ability more suitably, all of the heat conduction constructal problems may be re-optimized based on it. | WEI ShuHuan, CHEN LinGen & SUN FengRui Postgraduate School, Naval University of Engineering, Wuhan 430033, China | 2008 | Science China(Technological Sciences)2008,51,8: | 47 |
| 8 | Constructal optimization for geometry of cavity by taking entransy dissipation minimization as objective显示文摘The entransy dissipation extremum principle provides new warranty and criterion for optimization of heat transfer.For two cases(body with heat generation and body heated externally)of a solid conducting wall with an open cavity,a dimensionless equivalent thermal resistance based on entransy dissipation definition was taken as the optimization objective to optimize the model constructal ge- ometry.Numerical results validated the necessity and feasibility of the presented method.Comparisons of the numerical results based on minimization of dimensionless maximum thermal resistance and minimization of dimensionless equivalent thermal resistance,respectively,showed that there was no obvious difference between the two results when the volume fractionΦoccupied by cavity was small, but the difference between the two results increased with the increases ofΦand the body aspect ratio H/L for any model.The optimal cavities for bodies heated externally were more slender than those for bodies with heat generation.Heat origin had obvious effect on the global performance of heat transfer. The entransy dissipation of body heated externally increased 2―3 times than that of body with heat generation,indicating that the global performance of heat transfer weakened.The method presented herein provides some guidelines for some relevant thermal design problems. | XIE ZhiHui CHEN LinGen SUN FengRui | 2009 | Science China(Technological Sciences)2009,52,12: | 37 |
| 9 | A temperature prediction-correction method for estimating surface soil heat flux from soil temperature and moisture data显示文摘Surface soil heat flux is a component of surface energy budget and its estimation is needed in land-atmosphere interaction studies. This paper develops a new simple method to estimate soil heat flux from soil temperature and moisture observations. It gives soil temperature profile with the thermal diffusion equation and, then, adjusts the temperature profile with differences between observed and computed soil temperatures. The soil flux is obtained through integrating the soil temperature profile. Compared with previous methods, the new method does not require accurate thermal conductivity. Case studies based on observations, synthetic data, and sensitivity analyses show that the new method is preferable and the results obtained with it are not sensitive to the availability of temperature data in the topsoil. In addition, we pointed out that the soil heat flux measured with a heat-plate can be quite erroneous in magnitude though its phase is accurate. | Kun Yang JieMin Wang | 2008 | Science China Earth Sciences2008,51,5: | 39 |
| 10 | Thawing and freezing processes of active layer in Wudaoliang region of Tibetan Plateau显示文摘The interaction between permafrost and atmosphere is accomplished through transfer of heat and moisture in the overlay active layer. Thus, the research on the thermal and hydrodynamics of active layer during the thawing and freezing processes was considered a key to revealing the heat and moisture exchanges between permafrost and atmosphere. The monitoring and research on active layer were conducted because permafrost occupies about two thirds of the total area of the Tibetan Plateau. Based on the analysis of the ground temperature data and soil moisture data of monitoring near the Wudaoliang region of the Tibetan Plateau, the thawing and freezing processes of active layer were divided into four stages, i.e. summer thawing stage (ST), autumn freezing stage (AF), winter cooling stage (WC) and spring warming stage (SW). Coupled heat and water flow is much more complicated in ST and AF, and more amount of water is migrating in these two stages. Heat is transferred mainly via conductive heat flow in the | Lin Zhao Guodong Cheng Shuxun Li Xinmin Zhao Shaoling Wang | 2000 | Chinese Science Bulletin2000,45,23: | 31 |
| 11 | Analysis of aerodynamic and thermodynamic parameters on the grassy marshland surface of Tibetan Plateau | TSUKAMOTO Osamu ISHIKAWA Hirohiko TAMAGAWA Ichiro | 2002 | Progress in Natural Science:Materials International2002,12,1: | 34 |
| 12 | Interbasin freshwater, heat and salt transport through the boundaries of the East and South China Seas from a variable-grid global ocean circulation model显示文摘The monthly and annual mean freshwater, heat and salt transport through the openboundaries of the South and East China Seas derived from a variable-grid global ocean circulation model is reported. The model has 1/6 resolution for the seas adjacent to China and 3 resolution for the global ocean. The model results are in fairly good agreement with the existing estimates based on measurements. The computation shows that the flows passing through the South China Sea contribute volume, heat and salt transport of 5.3 Sv, 0.57 PW and 184 Ggs-1, respectively (about 1/4) to the Indonesian Throughflow, indicating that the South China Sea is an important pathway of the Pacific to Indian Ocean throughflow. The volume, heat and salt transport of the Kuroshio in the East China Sea is 25.6 Sv, 2.32 PW and 894 Ggs-1, respectively. Less than 1/4 of this transport passes through the passage between Iriomote and Okinawa. The calculation of heat balance indicates that the South China Sea absorbs net heat flux from the sun and atmosphere with a rate of 0.08 PW, while the atmosphere gains net heat flux from the Baohai, Yellow and East China Seas with a rate of 0.05 PW. | 方国洪 魏泽勋 崔秉昊 王凯 方越 李薇 | 2003 | Science China Earth Sciences2003,46,2: | 30 |
| 13 | Convective heat transfer and flow characteristics of Cu-water nanofluid显示文摘An experimental system is built to investigate convective heat transfer and flow characteristics of the nanofluid in a tube. Both the convective heat transfer coefficient and friction factor of Cu-water nanofluid for the laminar and turbulent flow are measured. The effects of such factors as the volume fraction of suspended nanoparticles and the Reynolds number on the heat transfer and flow characteristics are discussed in detail. The experimental results show that the suspended nanoparticles remarkably increase the convective heat transfer coefficient of the base fluid and show that the friction factor of the sample nanofluid with the low volume fraction of nanoparticles is almost not changed. Compared with the base fluid, for example, the convective heat transfer coefficient is increased about 60% for the nanofluid with 2.0 vol% Cu nanoparticles at the same Reynolds number. Considering the factors affecting the convective heat transfer coefficient of the nano- fluid, a new convective heat transfer correlation for nanofluid under single-phase flows in tubes is established. Comparison between the experimental data and the calculated results indicate that the correlation describes correctly the energy transport of the nanofluid. | 李强 宣益民 | 2002 | Science China(Technological Sciences)2002,45,4: | 29 |
| 14 | Optimal operation of electricity, natural gas and heat systems considering integrated demand responses and diversified storage devices显示文摘In recent years, the increasing penetration level of renewable generation and combined heat and power(CHP) technology in power systems is leading to significant changes in energy production and consumption patterns. As a result, the integrated planning and optimal operation of a multi-carrier energy(MCE) system have aroused widespread concern for reasonable utilization of multiple energy resources and efficient accommodation of renewable energy sources. In this context, an integrated demand response(IDR) scheme is designed to coordinate the operation of power to gas(P2 G) devices, heat pumps,diversified storage devices and flexible loads within an extended modeling framework of energy hubs. Subsequently, the optimal dispatch of interconnected electricity,natural gas and heat systems is implemented considering the interactions among multiple energy carriers by utilizing the bi-level optimization method. Finally, the proposed method is demonstrated with a 4-bus multi-energy systemand a larger test case comprised of a revised IEEE 118-bus power system and a 20-bus Belgian natural gas system. | Linna NI Weijia LIU Fushuan WEN Yusheng XUE Zhaoyang DONG Yu ZHENG Rui ZHANG | 2018 | Journal of Modern Power Systems and Clean Energy2018,6,3: | 30 |
| 15 | Constructal entransy dissipation rate and flow-resistance minimizations for cooling channels显示文摘Based on constructal theory,a construct of a volume that generates heat at every point and is cooled by the coolant in the constant or tapered channel is optimized by minimizing entransy dissipation rate and flow resistance.The optimal constructs of the rectangular elements with dimensionless mean thermal resistance minimization as well as the first-,secondand thirdorder assemblies with dimensionless global flow resistance minimizations are obtained respectively.The results show that both the mean temperature difference and the limiting temperature difference of rectangular elements based on EDR (entransy dissipation rate) and MTD (maximum temperature difference) minimizations respectively are almost equal.Comparing heat transfer performances from the two optimization procedures,the dimensionless global flow resistance is decreased more for the former procedure when the assembly’s order is high.It may create great superiority for constructal optimization to combine the entransy dissipation extreme principle with heat convection. | XIAO QingHua,CHEN LinGen & SUN FengRui Postgraduate School,Naval University of Engineering,Wuhan 430033,China | 2010 | Science China(Technological Sciences)2010,53,9: | 27 |
| 16 | Performance of a quantum heat engine cycle working with harmonic oscillator systems显示文摘A cycle model of an irreversible heat engine working with harmonic systems is established in this paper. Based on the equation of motion of an operator in the Heisenberg picture and semi-group approach, the first law of thermodynamics for a harmonic system and the time evolution of the system are obtained. The general expressions for several important parameters, such as the work, efficiency, power output, and rate of entropy production are derived. By means of numerical analysis, the optimally operating regions and the optimal values of performance parameters of the cycle are determined under the condition of maximum power output. At last, some special cases, such as high temperature limit and frictionless case, are dis-cussed in brief. | WANG JianHui HE JiZhou MAO ZhiYuan | 2007 | Science China(Physics,Mechanics & Astronomy)2007,50,2: | 25 |
| 17 | AtHsfA2 modulates expression of stress responsive genes and enhances tolerance to heat and oxidative stress in Arabidopsis显示文摘There is increasing evidence for considerable interlinking between the responses to heat stress and oxidative stress, and recent researches suggest heat shock transcription factors (Hsfs) play an important role in linking heat shock with oxidative stress signals. In this paper, we present evidence that AtHsfA2 modulated expression of stress responsive genes and enhanced tolerance to heat and oxidative stress in Arabidopsis. Using Northern blot and quantitative RT-PCR analysis, we demonstrated that the expression of AtHsfA2 was induced by not only HS but also oxidative stress. By functional analysis of AtHsfA2 knockout mutants and AtHsfA2 overexpressing transgenic plants, we also demonstrated that the mutants displayed reduced the basal and acquired thermotolerance as well as oxidative stress tolerance but the overexpression lines displayed increased tolerance to these stress. The phenotypes correlated with the expres-sion of some Hsps and APX1, ion leakage, H2O2 level and degree of oxidative injuries. These results showed that, by modulated expression of stress responsive genes, AtHsfA2 enhanced tolerance to heat and oxidative stress in Arabidopsis. So we suggest that AtHsfA2 plays an im-portant role in linking heat shock with oxidative stress signals. | LI Chunguang1,2, CHEN Qijun1, GAO Xinqi1,3, QI Bishu1, CHEN Naizhi1, XU Shouming1, CHEN Jia1 & WANG Xuechen1 1. State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100094, China 2. Department of Industry Engineering, Zhengzhou Institute of Aeronautic Industry Management, Zhengzhou 450015, China 3. College of Life Science, Qufu Normal University, Qufu Shandong 273165, China | 2005 | Science China(Life Sciences)2005,48,6: | 23 |
| 18 | Optimal configuration for a finite high-temperature source heat engine cycle with the complex heat transfer law显示文摘The optimal configuration of a heat engine operating between a finite high-temperature source and an infinite low-temperature reservoir is derived by using finite time thermodynamics based on a complex heat transfer law,including Newtonian heat transfer law,linear phenomenological heat transfer law,radiative heat transfer law,Dulong-Petit heat transfer law,generalized convective heat transfer law and generalized radiative heat transfer law,q ∝(△T n). In the engine model the only irreversibility of finite rate heat transfer is considered. The optimal relation between the power output and efficiency of the heat engine is also derived by using an equivalent temperature of the hot reservoir. The obtained results include those obtained in recent literature and can provide some theoretical guidance for the designs of practical engines. | LI Jun CHEN LinGen SUN FengRui | 2009 | Science China(Physics,Mechanics & Astronomy)2009,52,4: | 22 |
| 19 | Mechanical properties and corrosion behavior of selective laser melted 316L stainless steel after different heat treatment processes显示文摘Irregular grains, high interfacial stresses and anisotropic properties widely exist in 3D-printed metallic materials, and this paper investigated the effects of heat treatment on the microstructural, mechanical and corrosion properties of 316 L stainless steel fabricated by selective laser melting. Sub-grains and low-angle boundaries exist in the as-received selective laser melted(SLMed) 316 L stainless steel. After heat treatment at 1050℃, the sub-grains and low-angle boundaries changed slightly, and the stress state and strength decreased to some extent due to the decrease of dislocation density. After heat treatment at 1200℃, the grains became uniform, and the dislocation cells vanished, which led to a sharp decline in the hardness and strength. However, the ductility was improved after recrystallization heat treatment.The passive film thickness and corrosion potential of the SLMed 316 L stainless steel decreased after heat treatment, and the pitting potential also decreased due to the accelerated transition from metastable to steady-state pitting;this accelerated transition was caused by the presence of weak passive films at the enlarged pores after heat treatment, especially for an adequate solid solution treatment. | Decheng Kong Chaofang Dong Xiaoqing Ni Liang Zhang Jizheng Yao Cheng Man Xuequn Cheng Kui Xiao Xiaogang Li | 2019 | Journal of Materials Science & Technology2019,35,7: | 23 |
| 20 | Constructal optimization for a solid-gas reactor based on triangular element显示文摘Entropy generation minimization for heat and mass transfer process in a solid-gas reactor is carried out based on constructal theory by using triangular elemental area. The aspect ratio of the triangular elemental area is optimized under constraint conditions. A number of optimal triangular elements are assembled to a new large rectangular area, which is optimised again. The procedure is repeated until the control-volume is covered, and the complete analytical results are obtained. The effects of some parameters on minimum entropy generation are analysed by nu-merical examples. The results show that smaller entropy generation can be ob-tained when the optimization for a given volume is carried out on the basis of tri-angular elements than those obtained on the basis of rectangular elements. | ZHOU ShengBing CHEN LinGen SUN FengRui | 2008 | Science China(Technological Sciences)2008,51,9: | 21 |