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Interfacial reaction between AZ91D magnesium alloy melt and mild steel under high temperature

China Foundry 2024年第2期21卷 159-167页

作者： Jia-hong dai Jian-yue Zhang Bin Jiang Xiang-jun Xu zhong-tao Jiang hong-mei Xie Qing-shan Yang Guo-qing Zhang College of Materials Science and Engineering Yangtze Normal UniversityChongqing 408100China National Engineering Research Center for Magnesium Alloys College of Materials Science and EngineeringChongqing UniversityChongqing 400044China Chongqing Jiulongyuan High-tech Industry Group Co. Ltd.Chongqing 400080China Loncin Industry Co. Ltd.Chongqing 400080China Department of Materials Science and Engineering The Ohio State UniversityColumbusOH 43210USA Chongqing Key Laboratory of Materials Surface&Interface Science Chongqing University of Arts and SciencesChongqing 402160China School of Metallurgy and Material Engineering Chongqing University of Science and TechnologyChongqing 401331China

The metallurgical quality control of magnesium(Mg)and Mg alloys in melting process is required to ensure a satisfied mechanical and corrosion performance,while the typical used steel crucible introduces impurities and interfacial interaction during melting ***,a systematic study about impurities diffusion and interfacial interaction between molten Mg and steel is *** the present study,the interfacial reaction between molten AZ91D Mg alloy and mild steel during melting process was investigated with the melting temperatures of 700℃,750℃ and 800℃.The results show that Al(Fe,Mn)intermetallic layer is the intermetallic primarily formed at the interfaces of AZ91D melt and mild ***,Al_(8)(Mn,Fe)5is indexed between Al(Fe,Mn)and ***_(3)C appears between the mild steel and Al(Fe,Mn)at 700℃ and 750℃,but absent at 800℃ due to the increased solubility of carbon in Mg *** is found that the growth of the intermetallic layer is controlled by diffusion mechanism,and Al and Mn are the dominant diffusing species in the whole interfacial reaction *** measuring the thickness of different layers,the growth constant was *** increases from 1.89(±0.03)×10^(-12)m^(2)·s^(-1)at 700℃ to 3.05(±0.05)×10^(-12)m^(2)·s^(-1)at 750℃,and 5.18(±0.05)×10^(-12)m^(2)·s^(-1)at 800℃.Meanwhile,the content of Fe is linearly increased in AZ91D with the increase of holding time at 700℃ and 750℃,while it shows a significantly increment after holding for 8 h at 800℃,indicating holding temperature is more crucial to determine the Fe content of AZ91D than holding time.

关键词： AZ91D mild steel interface reaction intermetallic growth kinetics

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Decomposition of Different Litter Fractions in a Subtropical Bamboo Ecosystem as Affected by Experimental Nitrogen Deposition

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Pedosphere 2011年第6期21卷 685-695页

作者： TU Li-Hua HU hong-Ling HU Ting-Xing ZHANG Jian LIU Li LI Ren-hong dai hong-zhong LUO Shou-Hua Sichuan Provincial Key Laboratory of Forestry Ecological Engineering College of Forestry Sichuan Agricultural University Xingkang Road 46 Ya'an 625014 (China) Maize Research Institute Sichuan Agricultural University Ya'an 625014 (China) Sichuan Forestry Inventory and Plan Institute Chengdu 610081 (China)

As an important component of the global carbon （C） budget, litter decomposition in terrestrial ecosystems is greatly affected by the increasing nitrogen （N） deposition observed globally. We hypothesized that different litter fractions derived from a single tree species may respond to N deposition differently depending on the quality of the litter substrate. To test the hypothesis, a two-year field experiment was conducted using the litterbag method in a Pleioblastus amarus plantation in the rainy region of Southwest China. Four N treatment levels were applied： control （no N added）, low-N （50 kg N ha-1 year-1）, medium-N （150 kg N ha-a year-1）, and high-N （300 kg N ha-1 year-l）. We observed different patterns of mass loss for the three P. amarus litter fractions （leaves, sheaths, and twigs） of varying substrate quality in the control plots. There were two decomposition stages with different decay rates （fast rate in early stages and slow rate in the later stages） for leaves and sheaths, while we did not observe a slower phase for the decay of twigs during the 2-year study period. The annual decomposition rate （k） of twigs was significantly lower than that of leaves or sheaths. Addition of N slowed the decomposition of leaves and twigs in the later stages of decomposition by inhibiting the decay of lignin and cellulose, while addition of N did not affect the mass loss of sheaths during the study period. In the decomposition of all three litter fractions, experimental N deposition reduced the net N accumulation in the early stages and also decreased the net N release in the later stages. The results of this study suggest that litter substrate quality may be an important factor affecting litter decomposition in a bamboo ecosystem affected by N deposition.

关键词： decomposition rate litter substrate N dynamics plant biomass Pleioblastus amarus

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Effect of Nb-content on the corrosion resistance of Co-free high entropy alloys in chloride environment

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Tungsten 2024年第4期6卷 778-793页

作者： Peng-Fei dai Yang Zhang Sergey Rogozhkin Ji-hong Han Shu-Wen Li zhong-Wu Zhang Key Laboratory of Superlight Materials and Surface Technology Ministry of Education College of Materials Science and Chemical Engineering Harbin Engineering University National Research Nuclear University “MEPh I” National Research Center “Kurchatov Institute”

This study investigated the effect of Nb-content on the corrosion behavior of the Al7Cr20Fe35-xNi35Mo3Nbx（x=0,1 and 2）high-entropy alloys in a *** results indicated that only the face centered cubic phase existed in the NbO and Nbl alloys,while the emergence of Laves phase was observed when Nb-content reached 2 at.%.The NbO and Nb1alloys exhibited pitting corrosion,while the NiAl-rich phase experienced localized preferential corrosion in the Nb2 *** electrochemical results revealed that the corrosion current density of the Nbx（x=0,1 and 2） alloys fell within the range of 10-8-10-7A·cm-2,with a pitting corrosion potential exceeding 700 ***,the Nb1 alloy exhibited the most impressive corrosion resistance,as its corrosion current density(7 × 10-8A·cm-2) was merely half that of 316LN stainless *** is attributed to its rapid passivation process,resulting in the development of a protective film characterized by an increased Cr2O3/Al2O3+Cr（OH）*** study highlighted that the addition of Nb contributed to gram refinement,decreased corrosion current density,and elevated pitting potential,favoring passivation and improving corrosion ***,excessive Nb-content resulted in the emergence of the Laves phase,inducing galvanic corrosion and diminishing resistance to corrosion.

关键词： Corrosion High entropy alloys Microstructure Niobium Passive film

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Grain refinement of 5A06 aluminum alloy welds caused by tungsten inert gas welding arc characteristics under Ar-He alternating gas supply conditions:a coupled method of water-cooled copper plate test/numerical simulation

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Journal of Iron and Steel Research International 2024年第3期31卷 767-777页

作者： hong-bin dai Jian Miao Jia-xin Lin School of Materials Science and Engineering Harbin University of Science and TechnologyHarbin 150040HeilongjiangChina

The welding arc,as a carrier for the conversion of electrical energy to thermal energy,has a direct impact on the quality of welding by its properties and *** the tungsten inert gas(TIG)welding process under the condition of Ar-He alternating gas supply,the arc is alternately converted between Ar arc and He arc with an alternating gas supply cycle,which has obvious arc change *** FLUENT software was used to numerically simulate the characteristics of the TIG arc under the condition of alternating gas supply,and the arc temperature field,arc pressure,electric potential and current density distribution under the condition of alternating gas supply were *** with the real-time data of arc pressure measured by the water-cooled copper plate with holes,it is proved that the TIG arc has obvious dynamic characteristics under the condition of Ar-He alternating gas *** unique dynamic TIG arc acts on the 5A06 aluminum alloy weld,causing the molten pool to stir,resulting in uniform microstructure and grain refinement at the weld,and thereby improving the mechanical properties of the welded joint.

关键词： Alternating gas supply Grain refinement Numerical simulation Tungsten argon arc morphology Microstructure Mechanical property

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The Rate of Convergence of Augmented Lagrangian Method for Minimax Optimization Problems with Equality Constraints

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Journal of the Operations Research Society of China 2024年第2期12卷 265-297页

作者： Yu-hong dai Li-Wei Zhang LSEC ICMSECAMSSChinese Academy of SciencesBeijing 100190China Institute of Operations Research and Control Theory School of Mathematical SciencesDalian University of TechnologyDalian 116024China

The augmented Lagrangian function and the corresponding augmented Lagrangian method are constructed for solving a class of minimax optimization problems with equality *** prove that,under the linear independence constraint qualification and the second-order sufficiency optimality condition for the lower level problem and the second-order sufficiency optimality condition for the minimax problem,for a given multiplier vectorμ,the rate of convergence of the augmented Lagrangian method is linear with respect to||μu-μ^(*)||and the ratio constant is proportional to 1/c when the ratio|μ-μ^(*)||/c is small enough,where c is the penalty parameter that exceeds a threshold c_(*)>O andμ^(*)is the multiplier corresponding to a local ***,we prove that the sequence of multiplier vectors generated by the augmented Lagrangian method has at least Q-linear convergence if the sequence of penalty parameters(ck)is bounded and the convergence rate is superlinear if(ck)is increasing to ***,we use a direct way to establish the rate of convergence of the augmented Lagrangian method for the minimax problem with a quadratic objective function and linear equality constraints.

关键词： Minimax optimization Augmented Lagrangian method Rate of convergence Second-order sufficiency optimality

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Strong evidence for latitudinal diversity gradient in mosses across the world

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Plant Diversity 2024年第4期46卷 537-541页

作者： hong Qian Zun dai Jian Wang Research and Collections Center Illinois State Museum1011 East Ash StreetSpringfieldIL 62703USA Bryology Laboratory School of Life SciencesEast China Normal UniversityShanghai 200241China Shanghai Institute of Eco-Chongming(SIEC) 3663 Northern Zhongshan RoadShanghai 200062China

Species richness generally decreases with increasing latitude,a biodiversity gradient that has long been considered as one of the few laws in *** latitudinal diversity gradient has been observed in many major groups of *** plants,the latitudinal diversity gradient has been observed in vascular plants,angiosperms,ferns,and ***,a conspicuous latitudinal diversity gradient in mosses at a global or continental scale has not been observed until ***,we analyze a comprehensive data set including moss species in each band of 20° in latitude *** results show that moss species richness decreases strongly with increasing latitude,regardless of whether the globe is considered as a whole or different longitudinal segments(e.g.,Old World versus New World) are considered *** result holds when variation in area size among latitudinal bands is taken into ***'s correlation coefficient between latitude and species richness is-0.99 for both the Northern and Southern *** bryophytes are an extant lineage of early land plants and because mosses not only include most of extant species of bryophytes but also are important constituents of most terrestrial ecosystems,understanding geographic patterns of mosses is particularly important The finding of our study fills a critical knowledge gap.

关键词： Bryophyte Latitudinal diversity gradient Moss Species density Species diversity

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Multi-stream signals separation based on space-time-isomeric (SPATIO) array using metasurface antennas

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Science China(Information Sciences) 2024年第2期67卷 181-200页

作者： Yangming LOU Liang JIN Huiming WANG Zhou zhong Junyan dai PLA Strategic Support Force Information Engineering University School of Information and Communications Engineering Xi'an Jiaotong University 3. State Key Laboratory of Millimeter WavesSoutheast University

In spatial domain signal processing, it is necessary to equip more antennas at the receiver to improve spatial demultiplexing capability. However, increasing the number of antennas under restricted space will reduce antenna spacing and raise the channel correlation, making the number of signal streams spatially demultiplexed much smaller than that of antennas. This paper proposes a method to design a space-timeisomeric(SPATIO) array based on metasurface antennas under wireless multipath conditions. Each antenna in this array has a different pattern and varies independently with time, reducing the channel correlation by superposing multipath at distinct positions and moments. Based on the SPATIO array, we present an array parameter design scheme based on infinity norm minimization, which can maximize the received energy of each stream while separating multi-stream received signals. Simulation results illustrate the performance of the SPATIO array for multi-stream signal reception. Compared with conventional multiple-input multipleoutput arrays, the proposed array can reduce the bit error rate by one order of magnitude under the same simulation conditions.

关键词： multiple-input multiple-output metasurface antenna space-time-isomeric array multipath channel degree of freedom

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Metagenomics reveals the microbial community and functional metabolism variation in the partial nitritation-anammox process:From collapse to recovery

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Journal of Environmental Sciences 2024年第1期135卷 210-221页

作者： hong Wang Hui Gong Xiaohu dai Min Yang State Key Laboratory of Pollution Control and Resource Reuse College of Environmental Science and EngineeringTongji UniversityShanghai 200092China BIOMATH Department of Data Analysis and Mathematical ModellingGhent UniversityGhent 9000Belgium

Mainstream partial nitritation-anammox(PNA)process easily suffers from performance instability and even reactor collapse in ***,it is of great significance to unveil the characteristic of performance recovery,understand the intrinsic mechanism and then propose operational *** this study,we combined long-term reactor operation,batch tests,and metagenomics to reveal the succession of microbial community and functional metabolism variation from system collapse to *** aeration control(0.10-0.25mg O_(2)/L)was critical for performance *** was also found that Candidatus Brocadia became the dominant flora and its abundance increased from 3.5%to 11.0%.Significant enhancements in carbon metabolism and phospholipid biosynthesis were observed during system recovery,and the genes abundance related to signal transduction was dramatically *** up-regulation of sdh and suc genes showed the processes of succinate dehydrogenation and succinyl-CoA synthesis might stimulate the production of amino acids and the synthesis of proteins,thereby possibly improving the activity and abundance of AnAOB,which was conducive to the performance ***,the increase in abundance of hzs and hdh genes suggested the enhancement of the anammox *** in the abundance of key genes involved in nitrogen metabolism indicated that nitrogen removal pathway was more diverse after system *** achievement of performance recovery was driven by anammox,nitrification and denitrification coupled with dissimilatory nitrate reduction to *** results provide deeper insights into the recovery mechanism of PNA system and also provide a potential regulation strategy for the stable operation of the mainstream PNA process.

关键词： Partial nitritation-anammox Metagenomics Microbial community Functional metabolism Recovery

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Adjuvant therapy for hepatocellular carcinoma:Dilemmas at the start of a new era

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World Journal of Gastroenterology 2024年第8期30卷 806-810页

作者： Jian-hong zhong Department of Hepatobiliary Surgery Guangxi Medical University Cancer HospitalNanning 530021Guangxi Zhuang Autonomous RegionChina

Approximately 50%-70%of patients with hepatocellular carcinoma experience recurrence within five years after curative hepatic resection or *** a result,many patients receive adjuvant therapy after curative resection or ablation in order to prolong recurrence-free *** therapy recommended by national guidelines can differ,and guidelines do not specify when to initiate adjuvant therapy or how long to continue *** and other unanswered questions around adjuvant therapies make it difficult to optimize them and determine which may be more appropriate for a given type of *** questions need to be addressed by clinicians and researchers.

关键词： Adjuvant therapy Hepatocellular carcinoma Tumor recurrence Unanswered questions

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A Bio-Inspired Integration Model of Basal Ganglia and Cerebellum for Motion Learning of a Musculoskeletal Robot

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Journal of Systems Science & Complexity 2024年第1期37卷 82-113页

作者： ZHANG Jinhan CHEN Jiahao zhong Shanlin QIAO hong State Key Laboratory of Multimodal Artificial Intelligence Systems Institute of AutomationChinese Academy of SciencesBeijing 100190China School of Artificial Intelligence University of Chinese Academy of SciencesBeijing 100049China.

It is a significant research direction for highly complex musculoskeletal robots that how to develop the ability of motion learning and *** cooperations of multiple brain regions are crucial to improving motion *** by the neural mechanisms of structures,functions,and interconnections of basal ganglia and cerebellum,a biologically inspired integration model for motor learning of musculoskeletal robots is *** on the neural characteristics of the basal ganglia,the basal ganglia actor network,which mainly simulates the dorsal striatum,outputs motion commands,and the basal ganglia critic network,which simulates the ventral striatum,estimates actionstate *** network parameters are updated using the soft actor-critic *** on the sensorimotor prediction mechanism of the cerebellum,the cerebellum network evaluates the state feature extraction quality of the basal ganglia actor network and then updates the weights of its feature *** learning method is proven to converge to the optimal ***,drawing on the mechanism of dopaminergic dynamic regulation in the basal ganglia,the adaptive adjustment of target entropy and the dopaminergic experience replay are proposed to further improve the integration model,which contributes to the exploration-exploitation trade-off of motor *** bio-inspired integration model is validated on a musculoskeletal *** results indicate that this model can effectively control the musculoskeletal robot to accomplish the motion task from random starting locations to random target positions with high precision and robustness.

关键词： Basal ganglia and cerebellum bio-inspired integration model motion learning musculoskeletal robot reinforcement learning.

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