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Ultrahigh strength and uniform corrosion in Zn-li alloys through ultrahigh pressure supersaturated solid solution treatment for biodegradable orthopedic applications

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Rare Metals 2024年第10期43卷 5284-5304页

作者： Wan-Ying li Yi-Long Dai Wen-Hao Cai Si-Han lin lin Guo De-Chuang Zhang Yuncang li Cuie Wen School of Materials Science and Engineering Xiangtan University Department of Prosthodontics Shanghai Ninth People′s HospitalShanghai Jiao Tong University Key Laboratory of Low Dimensional Materials&Application Technology Ministry of EducationXiangtan University School of Engineering RMIT UniversityMelbourne

Zn-li alloys are considered promising candidate materials for biodegradable orthopedic implant applications due to their high mechanical performance and good ***,the presence of a large number of second-phase particles in this class of Zn alloys can lead to severe localized degradation due to micro-galvanic corrosion,which is detrimental to the mechanical integrity of the alloys during tissue healing in the human *** this study we report ultrahigh strength,uniform corrosion,good cytocompatibility,and effective antibacterial ability in Zn-x li（x=0.3,0.5,0.7;wt%） alloys achieved through supersaturated solid solution treatment （SSST） at 375℃ under ultrahigh pressure of 3 GPa.A high concentration of β-liZn4phases coexisted with the-Zn matrix in the as-cast Zn-x li alloys,whereas almost all the li dissolved into the-Zn matrix of SSST *** yield strength was 437 MPa for SSST Zn-0.3li,592 MPa for SSST Zn-0.5 li and 686 MPa for SSST *** SSST Zn-li alloys showed uniform degradation with remarkably reduced degradation rates compared to their as-cast *** 25% concentration extracts of the Zn-x li alloys demonstrated no cytotoxicity toward MC3T3-E1 cells,and the alloys exhibited effective antibacterial ability agains methicillin-resistant staphylococcus aureus.

关键词： Corrosion behavior Mechanical property Supersaturated solid solution treatment (SSST) Ultrahigh pressure Zn-li alloy

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悬吊式尺骨克氏针牵引治疗严重移位肱骨髁上骨折

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中华小儿外科杂志 1996年第3期17卷 166-168页

作者：韩镜明李达泉沈先涛代品华张文武汉市儿童医院骨科

采用悬吊式尺骨克氏针牵引方法减少和预防肘内翻，并评价该方法的优缺点。用悬吊式尺骨克氏针牵引治疗４５例严重移位肱骨髁上骨折，随访３０例，随访时间一年以上。根据骨牵引骨折复位情况和骨痂等级决定拔针时间。拔针前测量Ｂａｕｍ... 详细信息

采用悬吊式尺骨克氏针牵引方法减少和预防肘内翻，并评价该方法的优缺点。用悬吊式尺骨克氏针牵引治疗４５例严重移位肱骨髁上骨折，随访３０例，随访时间一年以上。根据骨牵引骨折复位情况和骨痂等级决定拔针时间。拔针前测量Ｂａｕｍａｎｎ角。随访３０例中，按照Ｄｏｄｇｔ＇ｓ标准，优２４例，良６例。无１例发生缺血性肌挛缩，无表面感染或因骨牵引产生神经症状。５例神经损伤均完全恢复。无明显肘内翻。该方法效果好、并发症少、易行且创伤小。可同时治疗骨折所致肿胀，随时在Ｘ线透视下再复位。但住院时间长是其不足。

关键词：骨折牵引肱骨骨折尺骨克氏针

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Enrichment of Chemical Element ^(7)li in the Rotating Red Clump Star

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Chinese Physics Letters 2024年第8期41卷 121-125页

作者： Fang-Wen Wu Han-Feng Song Qing-li li Yun He Xin-Yue Qu Zhuo Han College of Physics Guizhou UniversityGuiyang 550025China Geneva Observatory University of GenevaCH-1290 SauvernySwitzerland

About 2 percent of red clump stars are found to be the lithium-rich and thus the surface lithium increases obviously in some red clump *** physical mechanism of the lithium enrichment in these stars has not yet been explained satisfactorily by the evolutionary models of single *** flash induced internal gravity wave mixing(i.e.,IGW)could play a primary role in explaining the red clump star with lithium enrichment and it has a very significant impact on the internal structure and surface compositions of a *** can significantly increase the mixing efficiency of the internal gravity wave because the timescale for the enrichment event has been *** mixing can explain the observed behavior of lithium on red giant stars that are more luminosity than the RGB ***,it has a very small effect on the diffusion of elements because its diffusion coefficient is much smaller than the one of IGW induced mixing after the core helium flash.

关键词： flash stars lithium

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Chemical Activation of S/li2S in li-S Batteries by a Bidirectional Organic Redox Mediator

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Chemical Research in Chinese Universities 2024年第5期40卷 927-934页

作者： li Chengqiu ZHOU Chaoyong MEI Shilin YAO Changjiang State Key Laboratory of Explosion Science and Safety Protection School of Mechatronical EngineeringBeijing Institute of TechnologyBeijing100081P.R.China Xi’an Safty Energy Technology Co. Ltd.Xi’an710299P.R.China

The energy density and lifespan of prototype li-S batteries under high sulfur loading and lean electrolyte have been mainly restricted by the incomplete interconversion between insulating S8 and *** introduction of an electrocatalyst has been preserved as an effective way to breakthrough the bottleneck of the interconversion ***,we demonstrate a novel bidirectional redox mediator,insoluble dithiobisphthalimide(DTPI),as the electrocatalyst for both S8 reduction and li2S *** to the dual-functional role of both electron/li^(+)donor and acceptor,DTPI can efficiently accelerate the redox reactions during charge/discharge and significantly alleviate the incomplete conversion of sulfur ***,the li-S batteries with DTPI deliver superior specific capacity and cycling stability in comparison with those without ***,the redox mediator is scalable for synthesis and the DTPI-based 5 A·h pouch cell delivers a specific discharge capacity of around 870 mA·h·g^(−1) at 0.1 C(1 C=1675 mA/g)without capacity fading over 80 *** bidirectional catalysis mechanism has been studied through theoretical calculation and ex-situ characterization of the cathode *** work approves the effectiveness of bidirectional organic redox mediator in the construction of practical li-S batteries.

关键词： lithium-sulfur battery(LSB) Dithiobisphthalimide(DTPI) Organic redox mediator Interconversion

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Semi-automated detection of rangeland runoff and erosion control berms using high-resolution topography data

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International Soil and Water Conservation Research 2024年第1期12卷 217-226页

作者： li li Changjiang River Scientific Research Institute of Changjiang Water Resources Commission Wuhan430010China Research Center on Mountain Torrent&Geologic Disaster Prevention Ministry of Water ResourcesWuhan430010China University of Arizona School of Natural Resources and the EnvironmentTucsonAZ85719USA

An inventory of topographic modifications is essential to addressing their impacts on hydrological and morphological processes in human-altered ***,such inventories are generally *** study presents two workflows for semi-automatic detection of linear earthen runoff and erosion control berms in rangelands using high-resolution topographic *** workflows consist of initial object identification by applying either morphological grayscale reconstruction(MGR)or the Geomorphon(GEO)method,followed by identification refinements through filters based on objects’horizontal and vertical *** sites were selected within the Altar Valley,Arizona,in the southwestern United *** site was used for developing workflows and optimizing filter thresholds,and the other two sites were used to validate *** results showed that:1)The MGR-based workflow methodology could produce final precision and detection rates of up to 92%and 75%,respectively,and take less than 5 s for a 10.1 km^(2) site;2)The workflow based on the MGR method yielded greater identification accuracy than did the GEO workflow;3)Object length,orientation,and eccentricity were important characteristics for identifying earthen berms,and are sensitive to general channel flow direction and berm shape;4)Manual interrogation of topographic data and imagery can significantly improve identification precision *** proposed workflows will be useful for developing inventories of runoff and erosion control structures in support of sustainable rangeland management.

关键词： Earthen berm Rangeland Grayscale morphological reconstruction Geomorphon liDAR

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新型指令变换器测试系统设计

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现代电子技术 2017年第4期40卷 140-142,146页

作者：高金转李大全张会新熊继军中北大学电子测试技术国家重点实验室山西太原030051 仪器科学与动态测试教育部重点实验室山西太原030051 北京宇航系统研究所北京100076

指令变换器是测试飞行器工作参数和各路信号的关键设备,故设计一种新型的测试指令变换器工作的系统。该系统采用FPGA为主控制芯片,设计了4个模块,其中综合模块解析转发命令与数据,与其他3个模块配合接收和输出测试所需信号,包括48路电... 详细信息

指令变换器是测试飞行器工作参数和各路信号的关键设备,故设计一种新型的测试指令变换器工作的系统。该系统采用FPGA为主控制芯片,设计了4个模块,其中综合模块解析转发命令与数据,与其他3个模块配合接收和输出测试所需信号,包括48路电压可调的直流量模拟信号,8路时统信号以及PCM数据。试验结果表明,该系统可靠性高,性能稳定。

关键词：测试系统 FPGA 模拟信号指令变换器

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半固态流变压铸铝合金主轴承盖

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特种铸造及有色合金 2022年第7期42卷 917-920页

作者：任俊成陈颂李涛王泽忠唐元媛李大全梁小康李欣东风汽车集团有限公司技术中心武汉430058 有研工程技术研究院有限公司爱柯迪股份有限公司

某发动机主轴承盖采用半固态铝合金流变压铸工艺制造,相比原QT500-7球墨铸铁件减重45%,轻量化效果显著,零件性能满足设计要求。根据半固态铝合金319S的材料性能和半固态压铸工艺特点,对主轴承盖进行了结构重新设计和工艺仿真优化,采用... 详细信息

某发动机主轴承盖采用半固态铝合金流变压铸工艺制造,相比原QT500-7球墨铸铁件减重45%,轻量化效果显著,零件性能满足设计要求。根据半固态铝合金319S的材料性能和半固态压铸工艺特点,对主轴承盖进行了结构重新设计和工艺仿真优化,采用三级固溶热处理,得到的零件组织细密,力学性能高,内部无气孔、缩松等缺陷。零件通过10^(7)次单体台架疲劳试验验证,具有良好的应用前景。

关键词：半固态流变压铸主轴承盖铝合金轻量化

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湍流度随高度的变化及其对城市宏观地形的依赖

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热带地理 2019年第3期39卷 365-376页

作者：李大全孙武欧阳睿康黄盛高梦媛李庆祥黄启明华南师范大学地理科学学院广州510631 广东省建筑科学研究院集团股份有限公司风工程研究中心广州510500

分别构建广州主建成区垂直比例尺为1﹕2000、1﹕1000和1﹕500的3个建筑物模型,利用大型边界层风洞,在西北和东南两风向下,基于中性流模拟分析了复杂城市地形下湍流度随高度的变化及其对宏观地形的依赖。结果表明:风廓线指数α与不同高... 详细信息

分别构建广州主建成区垂直比例尺为1﹕2000、1﹕1000和1﹕500的3个建筑物模型,利用大型边界层风洞,在西北和东南两风向下,基于中性流模拟分析了复杂城市地形下湍流度随高度的变化及其对宏观地形的依赖。结果表明:风廓线指数α与不同高度的湍流度之间的关系密切,利用现有模型,根据4类粗糙度边界层和不同垂直比例尺,可确定相应的湍流度随高度变化模型的主要系数,预测精度高。城市地形下最大湍流度面发育在0~0.2h之间狭窄的范围内。用湍流度形态指数β来表征湍流度随高度的变化,无论城市屋脊还是平坦地形,随着风程区的延伸,廓线的指数α升高,湍流度形态指数β降低。表明同一高度湍流度值具有由迎风区、丘顶区向背风区增高,沿风程逐渐增大的规律,对地形部位和风程的依赖性强,与来流翻越简单地形时的特征一致。

关键词：城市地形湍流度廓线指数垂直结构风洞模拟广州

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Perturbed low-thrust geostationary orbit transfer guidance via polynomial costate estimation

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Chinese Journal of Aeronautics 2024年第3期37卷 181-193页

作者： Zhao li Hengnian li Fanghua JIANG Junfeng li State Key Laboratory of Astronautic Dynamics Xi’an Satellite Control CenterXi’an 710043China School of Aerospace Engineering Tsinghua UniversityBeijing 100084China

This paper proposes an optimal,robust,and efficient guidance scheme for the perturbed minimum-time low-thrust transfer toward the geostationary *** Earth’s oblateness perturbation and shadow are taken into *** is difficult for a Lyapunov-based or trajectory-tracking guidance method to possess multiple characteristics at the same time,including high guidance optimality,robustness,and onboard computational *** this work,a concise relationship between the minimum-time transfer problem with orbital averaging and its optimal solution is identified,which reveals that the five averaged initial costates that dominate the optimal thrust direction can be approximately determined by only four initial modified equinoctial orbit elements after a coordinate *** on this relationship,the optimal averaged trajectories constituting the training dataset are randomly generated around a nominal averaged *** polynomial regression models are trained on the training dataset and are regarded as the costate *** the transfer,the spacecraft can obtain the real-time approximate optimal thrust direction by combining the costate estimations provided by the estimators with the current state at any ***,all these computations onboard are *** simulation results show that the proposed guidance scheme possesses extremely high guidance optimality,robustness,and onboard computational efficiency.

关键词： Low thrust Orbital transfer Trajectory optimization Guidance Indirect method Orbital averaging Machine learning Geostationary satellites

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Theoretical Analysis of Cooperative Driving at Idealized Unsignalized Intersections

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Tsinghua Science and Technology 2024年第1期29卷 257-270页

作者： Shen li Jiawei Zhang Zhenwu Chen li li Department of Civil Engineering Tsinghua UniversityBeijing 100084China Department of Automation Tsinghua UniversityBeijing 100084China Shenzhen Urban Transport Planning Center Co. Ltd.Shenzhen 518000China

Cooperative driving is widely viewed as a promising method to better utilize limited road resources and alleviate traffic *** recent years,several cooperative driving approaches for idealized traffic scenarios(i.e.,uniform vehicle arrivals,lengths,and speeds)have been ***,theoretical analyses and comparisons of these approaches are *** this study,we propose a unified group-by-group zipper-style movement model to describe different approaches synthetically and evaluate their *** derive the maximum throughput for cooperative driving plans of idealized unsignalized intersections and discuss how to minimize the delay of *** obtained conclusions shed light on future cooperative driving studies.

关键词： cooperative driving connected and automated vehicles unsignalized intersection

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