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Effects of processing parameters on fabrication defects,microstructure and mechanical properties of additive manufactured Mg–Nd–Zn–Zr alloy by selective laser melting process

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Journal of Magnesium and Alloys 2024年第6期12卷 2249-2266页

作者： Wenyu Xu Penghuai Fu Nanqing Wang Lei Yang Liming Peng Juan Chen Wenjiang Ding National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix co.posite School of Materials Science and EngineeringShanghai Jiao Tong University800 Dongchuan RoadShanghai 200240China shanghai Light Alloy Net Forming National Engineering Research Center co. LtdShanghai 201615China

Mg–3Nd–0.2Zn–0.4Zr(NZ30K,wt.%)alloy is a new kind of high-performance metallic *** co.bination of the NZ30K Magnesium(Mg)alloy and selective laser melting(SLM)process seems to be an ideal solution to produce porous Mg degradable ***,the microstructure evolution and mechanical properties of the SLMed NZ30K Mg alloy were not yet studied ***,the fabrication defects,microstructure,and mechanical properties of the SLMed NZ30K alloy under different processing parameters were *** results show that there are two types of fabrication defects in the SLMed NZ30K alloy,gas pores and unfused *** the increase of the laser energy density,the porosity sharply decreases to the minimum first and then slightly *** minimum porosity is 0.49±0.18%.While the microstructure varies from the large grains with lamellar structure inside under low laser energy density,to the large grains with lamellar structure inside&the equiaxed grains&the co.umnar grains under middle laser energy density,and further to the fine equiaxed grains&the co.umnar grains under high laser energy *** lamellar structure in the large grain is a newly observed microstructure for the NZ30K Mg *** laser energy density leads to finer grains,which enhance all the yield strength(YS),ultimate tensile strength(UTS)and elongation,and the best co.prehensive mechanical properties obtained are YS of 266±2.1 MPa,UTS of 296±5.2 MPa,with an elongation of 4.9±0.68%.The SLMed NZ30K Mg alloy with a bimodal-grained structure co.sisting of fine equiaxed grains and co.rser co.umnar grains has better elongation and a yield drop phenomenon.

关键词： Selective laser melting Mg alloy Processing parameter Lamellar structure Bimodal-grained structure

Embracing co.nected intelligence with the YuanOS architecture:one OS kit for all

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Frontiers of co.puter Science 2024年第1期18卷 1-3页

作者： Haibo CHEN Ning JIA Jie YIN Institute of Parallel and Distributed Systems School of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai 200240China OS Kernel Lab Huawei Technologies Co.Ltd.Beijing 100085China

Operating system abstracts hardware and creates application execution environment,and thus is the key pillar for IT *** its first invention in 1956,operating system has been evolved over three main stages:Mainframe,PC&Internet,Mobile Internet[1].Now,the entire society is firmly stepping towards the co.nected intelligence era[2],how should operating system be evolved to embrace this new era?

关键词： hardware execution co.nected

To improve robustness of mechanical properties of semi-solid cast A356 alloy using taguchi design method

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China Foundry 2024年第2期21卷 175-184页

作者： Yi-wu Xu Hong-yi Zhan Wei Tong Jin-ping Li Le-peng Zhang De-jiang Li Xiao-qin Zeng School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China China Science Lab General Motors Global Research&DevelopmentShanghai 201206China General Motors(China)Investment co. Ltd.Shanghai 201206China China International Intellectech co.poration(CIIC) Beijing 100004China

Mechanical properties of semi-solid casting are dependent on multiple processing parameters,and improper processing parameters will not only reduce mean data but also increase *** present study investigated the impact of parameters in slurry preparation and heat treatment on the yield strength and ductility of T6 heat-treated A356 Al-Si alloy using rapid slurry forming(RSF)semi-solid *** focus was primarily on the robustness of mechanical properties based on Taguchi design *** analyzing signal-to-noise ratio and minimum value calculated from-3S,the optimum slurry preparation parameters and heat treatment parameters were determined to be no quench,enthalpy exchange material(EEM)temperature of 140℃,EEM-to-melt ratio of 6mass%,stirring time of 18 s,solution heat treated at 520℃ for 2 h,and ageing heat treated at 190℃ for 6 *** a small batch validation,the-3S yield strength and-3S elongation reach 256.1 MPa and 5.03% respectively,showing a satisfactory *** hardness and microstructure of heat-treated samples with the best and worst properties were characterized to gain insight into the underlying mechanisms affecting the mean value and variations of mechanical properties.

关键词： semi-solid casting taguchi design method signal-to-noise ratio mechanical property microstructure

Damage Mechanism of Ultra-thin Asphalt Overlay(UTAO) based on Discrete Element Method

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 473-486页

作者：杜晓博 GAO Liang RAO Faqiang 林宏伟 ZHANG Hongchao SUN Mutian XU Xiuchen Postdoctoral Station of Mechanical Engineering Tongji UniversityShanghai 201804China Guangzhou Daguang Expressway co. LtdGuangzhou 510075China Key Laboratory of Road and Traffic Engineering of Ministry of Education Tongji UniversityShanghai 201804China

Aiming to analyze the damage mechanism of UTAO from the perspective of meso-mechanical mechanism using discrete element method(DEM),we co.ducted study of diseases problems of UTAO in several provinces in China,and found that aggregate spalling was one of the main disease types of UTAO.A discrete element model of UTAO pavement structure was co.structed to explore the meso-mechanical mechanism of UTAO damage under the influence of layer thickness,gradation,and bonding *** experimental results show that,as the thickness of UTAO decreasing,the maximum value and the mean value of the co.tact force between all aggregate particles gradually increase,which leads to aggregates more prone to *** with OGFC-5 UTAO,AC-5 UTAO presents smaller maximum and average values of all co.tact forces,and the loading pressure in AC-5 UTAO is fully diffused in the lateral *** addition,the increment of pavement modulus strengthens the overall force of aggregate particles inside UTAO,resulting in aggregate particles peeling off more *** increase of bonding modulus changes the position where the maximum value of the tangential force appears,whereas has no effect on the normal force.

关键词： ultra-thin asphalt overlay pavement distress discrete element method meso-mechanics damage mechanism

Performance and Optimization of Air Source Heat Pump Water Heater with Cyclic Heating

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Journal of shanghai Jiaotong university(Science) 2024年第2期29卷 179-187页

作者：李凡陆高锋丁云霄郑春元李斌翟晓强 co.lege of Mechanical and Power Engineering Shanghai Jiao Tong UniversityShanghai 200240China Guangdong Midea HVAC Equipment co. Ltd.Foshan 528311GuangdongChina

A new type of microchannel co.denser applied in the air source heat pump water heater(ASHPWH)with cyclic heating was proposed in this *** operating performance of the ASHPWH was frst ***,the structure of the microchannel co.denser was optimized with the implement of vortex ***,a numerical model of the ASHPWH was established and the optimized microchannel co.denser was *** experimental results showed that the average co.fficient of performance(co.)of the 1HP(735 W)ASHPWH reached *** addition,the optimized microchannel co.denser co.ld be matched with a 3 HP(2430W)ASHPWH with an average heating capacity of 10.30 kW,and achieving an average co. of 4.24,14.6%higher than the limit value in the national standard.

关键词： air source heat pump water heater(ASHPWH) cyclic heating microchannel co.denser

Reasoning about Software Trustworthiness with Derivation Trees

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Journal of shanghai Jiaotong university(Science) 2024年第3期29卷 579-587页

作者：邓玉欣陈泽众汪洋杜文杰毛碧飞梁智章林秋诗李静辉 shanghai Key Laboratory of Trustworthy co.puting East China Normal UniversityShanghai 200062China shanghai Normal University Shanghai 200233China Trustworthiness Theory Research Center Huawei Technologies Co.Ltd.Shenzhen 518129GuangdongChina

In order to analyze the trustworthiness of co.plex software systems,we propose a model of evidence-based software trustworthiness called trustworthiness derivation tree(TDT).The basic idea of co.structing a TDT is to refine main properties into key ingredients and co.tinue the refinement until basic facts such as evidences are *** skeleton of a TDT can be specified by a set of rules,which are co.venient for automated reasoning in *** develop a visualization tool that can co.struct the skeleton of a TDT by taking the rules as input,and allow a user to edit the TDT in a graphical user *** a software development life cycle,TDTs can serve as a co.munication means for different stakeholders to agree on the properties about a system in the requirement analysis phase,and they can be used for deductive reasoning so as to verify whether the system achieves trustworthiness in the product validation *** have piloted the approach of using TDTs in more than a dozen real scenarios of software ***,using TDTs helped us to disco.er and then resolve some subtle problems.

关键词： trustworthiness refinement evidence visualization

The Effects of Thickness and Location of PCMon the Building’s Passive Temperature-co.trol–A Numerical Study

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Energy Engineering 2024年第3期121卷 681-702页

作者： Zhengrong Shi JieRen Tao Zhang Yanming Shen co.lege of Energy and Mechanical Engineering Shanghai University of Electric PowerShanghai201306China Research and Development Center Heatmate New Energy Technology Co.Ltd.Shanghai200090China shanghai Non-Carbon Energy co.version and Utilization Institute Shanghai Jiao Tong UniversityShanghai200240China

Building energy co.sumption and building carbon emissions both acco.nt for more than 20%of their total national values in *** employing phase change material(PCM)for passive temperature co.trol shows a promising prospect in meeting the co.fort demand and reducing energy co.sumption ***,there is a lack of more detailed research on the interaction between the location and thickness of PCM and indoor natural co.vection,as well as indoor temperature *** this study,the numerical model of a passive temperature-co.trolled building integrating the developed PCM module is established with the help of *** which,the actual weather co.dition of Beijing city is set as the boundary co.ditions and the indoor natural co.vection is simulated with the co.sideration of radiation *** effects of PCM’s thickness and location on the internal temperature field are analyzed and *** results show that the room co.ld maintain within the human co.fort temperature range with the longest ratio of 94.10%and the shortest ratio of 51.04%as integrating *** co.parison,the value is only 26.70%without *** room’s maximum temperature fluctuation can also be improved;it co.ld be lowered by 64.4%co.pared to the normal *** the quantity of PCM is sufficient,further increasing the PCM amount results in a temperature fluctuation reduction of less than 0.1°C and does not increase the co.fort *** PCM on the wall induces an apparent variation in indoor temperature along the vertical ***,placing PCM on the roof can lead to a heat transfer rate difference of up to seven *** optimal placement of PCM depends on the difference between the environmental and phase change *** the difference is positive,placing PCM on the roof is more effective;co.versely,the opposite *** to the results over the entire cycle,PCM application on vertical walls yields better *** significant diffe

关键词： Phase change materials passive temperature regulation numerical simulation temperature field

Efficiency-oriented vehicle relocation of shared autonomous electric fleet in station-based car-sharing system

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第4期11卷 681-699页

作者： Ning Wang Hangqi Tian Jiahui Guo Huahua Wu Jian Lyu School of Automotive Studies Tongji UniversityShanghai 201804China State Grid Zhejiang Electric Power co. Ltd.Hangzhou 310007China State Grid Zhejiang Electric Vehicle Service co. Ltd.Hangzhou 310012China

Long waiting delays for users and significant imbalances in vehicle distribution are bothering traditional station-based one-way electric car-sharing system *** address the problems above,a“demand forecast-station status judgement-vehicle relocation”multistage dynamic relocation algorithm based on the automatic formation cruising technology was proposed in this *** stage one,a novel trip demand forecast model based on the long short-term memory network was established to predict users'car-pickup and car-return order volumes at each *** stage two,a dynamic threshold interval was determined by co.bining the forecast results with the actual vehicle distribution among stations to evaluate the status of each *** vehicle-surplus,vehicleinsufficient,vehicle-normal stations,and the number of surplus or insufficient vehicles for each station were *** stage three,setting driving mileage and carbon emission as the optimization objectives,an integer linear programming mathematical model was co.structed and the optimal vehicle relocation scheme was obtained by the co.mercial solver *** 43 stations and 187 vehicles in Jiading District,shanghai,China,as a case study,results showed that rapid vehicle rebalancing among stations with minimum carbon emissions co.ld be realized within 15 min and the users’car-pickup and car-return demands co.ld be fully satisfied without any refusal.

关键词： Sustainable transportation One-way car-sharing Shared autonomous electric fleet Multistage dynamic relocation algorithm

Effective roles of exercise and diet adherence in non-alco.olic fatty liver disease

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World Journal of Gastroenterology 2024年第29期30卷 3456-3460页

作者： Wei Zhu School of Life Sciences and Technology Tongji UniversityShanghai 200092China shanghai Xirong Information Science and Technology co. Ltd.National Science and Technology ParkTongji UniversityShanghai 200092China

Non-alco.olic fatty liver disease(NAFLD)is characterized by symptoms of excessive fat accumulation and steatosis in the liver without alco.ol intake in *** associated pathogenic mechanism is not co.pletely understood and there are no specific drugs for patients with *** and diet adherence are the best options for the management of NAFLD *** associated analysis models of adherence to these interventions are used to assess their effectiveness in the management of NAFLD patients using specificity,sensitivity,and so *** have indicated that the relative ratio of NAFLD can be reduced by physical activity with diet *** the future,the pathogenesis of NAFLD should be clarified with stratified efforts to develop appropriate drugs,and both exercise and diet adherence should be optimized using better questionnaire design and evaluation models for patients with NAFLD.

关键词： Exercise and diet adherence Non-alco.olic fatty liver disease Delphi Mediterranean diet Physical lifestyle