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Review on laser directed energy deposited aluminum alloys

International Journal of Extreme Manufacturing 2024年第2期6卷 84-131页

作者： Tian-Shu Liu Peng Chen Feng qiu Hong-Yu Yang Nicholas Tan Yew Jin Youxiang Chew Di Wang Ruidi Li qi-chuan jiang Chaolin Tan Singapore Institute of Manufacturing Technology(SIMTech) Agency for ScienceTechnology and Research(A∗STAR)5 Cleantech LoopSingapore 636732Singapore State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130025People’s Republic of China Key Laboratory of Automobile Materials Ministry of Education and Department of Materials Science and EngineeringJilin UniversityChangchun 130025People’s Republic of China School of Mechanical&Automotive Engineering South China University of TechnologyGuangzhou 510640People’s Republic of China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083People’s Republic of China

Lightweight aluminum(Al)alloys have been widely used in frontier fields like aerospace and automotive industries,which attracts great interest in additive manufacturing(AM)to process high-value Al *** a mainstream AM technique,laser-directed energy deposition(LDED)shows good scalability to meet the requirements for large-format component manufacturing and ***,LDED Al alloys are highly challenging due to their inherent poor printability(*** laser absorption,high oxidation sensitivity and cracking tendency).To further promote the development of LDED high-performance Al alloys,this review offers a deep understanding of the challenges and strategies to improve printability in LDED Al *** porosity,cracking,distortion,inclusions,element evaporation and resultant inferior mechanical properties(worse than laser powder bed fusion)are the key challenges in LDED Al *** parameter optimizations,in-situ alloy design,reinforcing particle addition and field assistance are the efficient approaches to improving the printability and performance of LDED Al *** underlying correlations between processes,alloy innovation,characteristic microstructures,and achievable performances in LDED Al alloys are *** benchmark mechanical properties and primary strengthening mechanism of LDED Al alloys are *** review aims to provide a critical and in-depth evaluation of current progress in LDED Al *** opportunities and perspectives in LDED high-performance Al alloys are also outlined.

关键词： additive manufacturing laser directed energy deposition(LDED) aluminum alloys printability aluminum matrix composite auxiliary fields mechanical properties

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C-CORE:Clustering by Code Representation to Prioritize Test Cases in Compiler Testing

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 2069-2093页

作者： Wei Zhou Xincong jiang chuan qin School of Electronic Information and Electrical Engineering Shanghai Jiao Tong UniversityShanghai200240China Hikvision Research Institute Hangzhou Hikvision Digital Technology Co.Ltd.Hangzhou310051China

Edge devices,due to their limited computational and storage resources,often require the use of compilers for program ***,ensuring the security and reliability of these compilers is of paramount importance in the emerging field of edge *** widely used testing method for this purpose is fuzz testing,which detects bugs by inputting random test cases into the target ***,this process consumes significant time and *** improve the efficiency of compiler fuzz testing,it is common practice to utilize test case prioritization *** researchers use machine learning to predict the code coverage of test cases,aiming to maximize the test capability for the target compiler by increasing the overall predicted coverage of the test ***,these methods can only forecast the code coverage of the compiler at a specific optimization level,potentially missing many optimization-related *** this paper,we introduce C-CORE(short for Clustering by Code Representation),the first framework to prioritize test cases according to their code representations,which are derived directly from the source *** approach avoids being limited to specific compiler states and extends to a broader range of compiler ***,we first train a scaled pre-trained programming language model to capture as many common features as possible from the test cases generated by a *** this pre-trained model,we then train two downstream models:one for predicting the likelihood of triggering a bug and another for identifying code representations associated with ***,we cluster the test cases according to their code representations and select the highest-scoring test case from each cluster as the high-quality test *** reduction in redundant testing cases leads to time *** evaluation results reveal that code representations are better at distinguishing test capabilities,and C-CORE significantly enhanc

关键词： Compiler testing test case prioritization code representation

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Particle Distribution Informed by Chain Rigidity in Diblock Copolymer Melts: The Effect of Entropy

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Chinese Journal of Polymer Science 2024年第3期42卷 388-399,I0009页

作者： Yuguo Chen Shuanhu qi Ying jiang School of Chemistry Beihang UniversityBeijing 100191China

We study the effect of chain rigidity on tailoring the nanoparticle locations for neutral and selective particles embedded in the lamellar morphology formed by semiflexible diblock copolymer chains using self-consistent field calculations. The nanoparticles are modeled through a cavity function, and the semiflexible chains are represented by the continuous Kratsky-Porod chain model. In general situation, the nanoparticles prefer to stay at the interface in order to reduce the interface areas and thus the system free energy. However, the particle distribution at the domain center is subtle, and the underlying physics is intrinsically different depending on the polymer flexibility. In the case of flexible chains, the entropy just contributes a constant shift to the free energy when the nanoparticles move around the domain center indicating that the local metastable state if appears at the domain center is wholly attributed to the local minimum in the enthalpy. If the polymers are rigid, the variation of the particle distribution at the domain center has a close relation with the polymer rigidity and nanoparticle size. In the case of strongly rigid polymers with small nanoparticles, a nearly uniform particle distribution at the domain center is observed, while in other cases, a local enhancement of particle distribution there is found. In contrast to the case of flexible chains, further analysis reveals the crucial role of entropy in controlling the shape of particle distributions at the phase domain. Specifically, the local metastable state appears in the domain center is determined by the large entropy there which arises from the weak coupling of bond orientations that allows the polymer chains to be relatively relaxed. When the particle becomes selective, its distribution in the phase domain exhibits a shift almost uniformly rather than changes its profile, and the underlying physics still holds. In all, our study establishes a strong coupling between the chain rigi

关键词： Semiflexible diblock copolymer Nanoparticle distribution Self-consistent field theory Entropic effect

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Adaptive fault-tolerant control for non-minimum phase hypersonic vehicles based on adaptive dynamic programming

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Chinese Journal of Aeronautics 2024年第3期37卷 290-311页

作者： Le WANG Ruiyun qi Bin jiang State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China

In this paper,a novel adaptive Fault-Tolerant Control(FTC)strategy is proposed for non-minimum phase Hypersonic Vehicles(HSVs)that are affected by actuator faults and parameter *** strategy is based on the output redefinition method and Adaptive Dynamic Programming(ADP).The intelligent FTC scheme consists of two main parts:a basic fault-tolerant and stable controller and an ADP-based supplementary *** the basic FTC part,an output redefinition approach is designed to make zero-dynamics stable with respect to the new ***,Ideal Internal Dynamic(IID)is obtained using an optimal bounded inversion approach,and a tracking controller is designed for the new output to realize output tracking of the nonminimum phase HSV *** the ADP-based compensation control part,an ActionDependent Heuristic Dynamic Programming(ADHDP)adopting an actor-critic learning structure is utilized to further optimize the tracking performance of the HSV control ***,simulation results are provided to verify the effectiveness and efficiency of the proposed FTC algorithm.

关键词： Hypersonic vehicle Fault-tolerant control Non-minimum phase system Adaptive control Nonlinear control Adaptive dynamic programming

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Boosted photocatalytic removal of NO using direct Z-scheme UiO-66-NH2/Bi2MoO6 nanoflowers heterojunction:mechanism insight and humidity effect

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Rare Metals 2024年第8期43卷 3758-3770页

作者： jiang-Yu-Shan Liang Hai-Tao Ren Abdelkader Labidi qiu-Hui Zhu qi-Bing Dong Ahmed A.Allam Ahmed Rady chuan-Yi Wang School of Environmental Science and Engineering Shaanxi University of Science and Technology Zoology Department Faculty of ScienceBeni-Suef University Department of Zoology College of ScienceKing Saud University

In practical applications,relative humidity in the air is a key factor affecting the photocatalytic removal of NO,which is often overlooked in previous ***,we developed a direct Z-scheme UiO-66-NH2/Bi2MoO6heterojunction with a nanoflower-like structure to systematically investigate the effect of relative humidity on photocatalytic removal of *** optimized heterojunction for the removal efficiency of NO was 71.6% at1.07 mg·m-3NO concentration（relative humidity=10%）,and the generation of NO2was only 1.1%.Interestingly,with the increase in relative humidity,it showed a higher inhibition effect on NO2,while the removal of NO decreased slightly（8%）,which might be attributed to the affinity effect of NO2with water molecules and the competitive adsorption of H2O and NO on the surface of the heterojunction ***,the reaction pathways of NO removal at the developed heterojunctions were revealed by in situ DRIFTS *** work provides a novel vision for the development of direct Z-scheme heterojunction photocatalysts to effectively remove NO and inhibit the formation of toxic intermediate NO2under different humidities.

关键词： NO removal Relative humidity Direct Z-scheme Bismuth molybdate Visible-light photocatalysis

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Review on heat-to-power conversion technologies for hypersonic vehicles

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Chinese Journal of Aeronautics 2024年第5期37卷 148-179页

作者： Yinke qi Xiaofeng MA Peixue jiang Yinhai ZHU Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Energy and Power EngineeringTsinghua UniversityBeijing 100084China Beijing Key Laboratory of CO_(2)Utilization and Reduction Technology Department of Energy and Power EngineeringTsinghua UniversityBeijing 100084China

Hypersonic vehicles have enormous military and economic value,while their power and thermal protection demands will increase substantially with the rise in Mach number and *** the tremendous high-quality heat on the vehicle surface and engine wall into electrical energy through heat-to-power technologies will not only play a role in thermal protection,but also supply power for the *** paper provides a comprehensive review of heat-to-power conversion technologies on hypersonic vehicles,including the indirect conversion of Brayton and Rankine cycles,direct conversion of thermoelectric materials,and combined *** the open Brayton cycle with hydrocarbon fuel as the working fluid,the Power-to-Weight Ratio(PWR)can achieve the highest,at around 1.8,due to the high PWR of the hydrocarbon fuel turbine and the few components of the ***,its work capacity is limited by the flow rate of the supplied *** closed Brayton cycle can maintain a relatively high PWR,ranging from 0.2 to 0.8,while achieving relatively high output power and conversion *** Rankine cycle has a higher PWR,its range is close to that of the closed Brayton cycle,peaking at about *** thermoelectric materials technology has a small power generation level,making it more suitable for scenarios with low power *** review provides a basis for selecting and developing heat-to-power conversion technologies on hypersonic vehicles.

关键词： Hypersonic vehicles Heat-to-power conversion Brayton cycle Rankine cycle Thermoelectric materials

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The Relationship Between Oxidation and Thermal Fatigue of Martensitic Hot-Work Die Steels

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Acta Metallurgica Sinica(English Letters) 2018年第7期31卷 692-698页

作者： qi-chuan jiang Xu-Min Zhao Feng qiu Tian-Ning Ma qing-Long Zhao Key Laboratory of Automobile Materials Ministry of Education College of Materials Science and EngineeringJilin University jiangsu Jin Gang Special Steel Co. Ltd

Thermal fatigue behaviors of two forged hot-work die steels subjected to cyclic heating （650 ℃）-water quenching were investigated. A martensitic hot-work die steel containing 10% Cr （HHD）, showing superior oxidation resistance and thermal fatigue resistance to the commercial martensitic hot-work die steel （Uddeholm DIEVAR ）, was developed. The maximal crack length in HHD was 35% shorter than that in DIEVAR after 2000 thermal cycles, and the hot yield strength at 650℃ of HHD was 14% lower than that of DIEVAR prior to thermal fatigue testing, which is 30% higher after 1500 cycles. It is found that cracks initiated and propagated along the oxide layers in the grain boundaries, suggesting that the oxidation-induced thermal fatigue cracks can significantly reduce the mechanical performance and service life for the hot- work die steel. High-temperature oxidation behavior is crucial for thermal fatigue crack formation, while high-temperature yield strength and ductility play a less important role.

关键词： High-temperature oxidation Crack initiation and propagation Strength and plasticity Thermal fatigueresistance Tool steel

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A Planning Method for Operational Test of UAV Swarm Based on Mission Reliability

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1889-1918页

作者： Jingyu Wang Ping jiang Jianjun qi College of Systems Engineering National University of Defense TechnologyChangsha410073China Beijing Special Engineering Design Institution Beijing100028China

The unmanned aerial vehicle(UAV)swarm plays an increasingly important role in the modern battlefield,and the UAV swarm operational test is a vital means to validate the combat effectiveness of the UAV *** to the high cost and long duration of operational tests,it is essential to plan the test in *** solve the problem of planning UAV swarm operational test,this study considers the multi-stage feature of a UAV swarm mission,composed of launch,flight and combat stages,and proposes a method to find test plans that can maximize mission ***,a multi-stage mission reliability model for a UAV swarm is proposed to ensure successful implementation of the mission.A multi-objective integer optimization method that considers both mission reliability and cost is then formulated to obtain the optimal test *** study first constructs a mission reliability model for the UAV swarm in the combat ***,the launch stage and flight stage are integrated to develop a complete PMS(Phased Mission Systems)reliability ***,the Binary Decision Diagrams(BDD)and Multi Objective Quantum Particle Swarm Optimization(MOQPSO)methods are proposed to solve the *** optimal plans considering both reliability and cost are *** proposed model supports the planning of UAV swarm operational tests and represents a meaningful exploration of UAV swarm test planning.

关键词： UAV swarm PMS MOQPSO BDD mission reliability operational test planning

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Understanding the spatial interaction of ultrasounds based on three-dimensional dual-frequency ultrasonic field numerical simulation

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China Foundry 2024年第1期21卷 29-43页

作者： Zhao-yang Yin qi-chi Le Yan-chao jiang Da-zhi Zhao qi-yu Liao qi Zou Key Lab of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang 110819China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China

A transient 3D model was established to investigate the effect of spatial interaction of ultrasounds on the dual-frequency ultrasonic field in magnesium alloy *** effects of insertion depth and tip shape of the ultrasonic rods,input pressures and their ratio on the acoustic field distribution were discussed in ***,the spacing,angle,and insertion depth of two ultrasonic rods significantly affect the interaction between distinct *** a result,various acoustic pressure distributions and cavitation regions are *** spherical rods mitigate the longitudinal and transversal attenuation of acoustic pressure and expand the cavitation volume by 53.7%and 31.7%,respectively,compared to the plate and conical *** the input pressure will enlarge the cavitation region but has no effect on the acoustic pressure distribution *** acoustic pressure ratio significantly affects the pressure distribution and the cavitation region,and the best cavitation effect is obtained at the ratio of 2:1(P15:P20).

关键词： dual-frequency ultrasonic numerical model acoustic pressure spatial interaction magnesium alloy

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A Dual Closed-Loop Digital Twin Construction Method for Optimizing the Copper Disc Casting Process

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IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 581-594页

作者： Zhaohui jiang chuan Xu Jinshi Liu Weichao Luo Zhiwen Chen Weihua Gui IEEE the School of Automation Central South UniversityChangsha 410083China the Peng Cheng Laboratory Shenzhen 518000China

The copper disc casting machine is core equipment for producing copper anode plates in the copper metallurgy *** copper disc casting machine casting package motion curve(CPMC) is significant for precise casting and efficient ***,the lack of exact casting modeling and real-time simulation information severely restricts dynamic CPMC *** this end,a liquid copper droplet model describes the casting package copper flow pattern in the casting ***,a CPMC optimization model is proposed for the first *** top of this,a digital twin dual closed-loop self-optimization application framework(DT-DCS) is constructed for optimizing the copper disc casting process to achieve self-optimization of the CPMC and closed-loop feedback of manufacturing information during the casting ***,a case study is carried out based on the proposed methods in the industrial field.

关键词： Copper disc casting machine digital twin(DT) mechanism modeling self-optimization

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