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铸造发动机用Mg-3.5Al-RE镁合金的组织与性能研究

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稀土 2024年第4期45卷 130-138页

作者：刘祥林波宁萍任飞迟成飞赵鹏展重庆科创职业学院重庆402160 重庆交通大学航运与船舶工程学院重庆400074 重庆大学机械与运载工程学院重庆400044 重庆城市职业学院重庆402160

采用真空熔炼+压铸的方法制备了Mg-3.5Al-RE镁合金(RE=La、Ce和Nd)和Mg-3.5Al-3Nd-0.9Zn-0.15Mn镁合金,研究了稀土元素和微量Zn、Mn元素对压铸镁合金物相组成、显微组织、力学性能、导热性能和流动性能的影响。结果表明,压铸Mg-3.5Al-R... 详细信息

采用真空熔炼+压铸的方法制备了Mg-3.5Al-RE镁合金(RE=La、Ce和Nd)和Mg-3.5Al-3Nd-0.9Zn-0.15Mn镁合金,研究了稀土元素和微量Zn、Mn元素对压铸镁合金物相组成、显微组织、力学性能、导热性能和流动性能的影响。结果表明,压铸Mg-3.5Al-RE镁合金主要由α-Mg基体、短棒状/鱼骨状Al_(11)RE_(3)或颗粒状Al_(2)RE相组成,平均晶粒尺寸从大至小顺序为:RE=La>RE=Ce>RE=Nd,抗拉强度、断后伸长率从高至低顺序为:RE=Nd>RE=Ce>RE=La,导热系数从高至低顺序为RE=Ce>RE=La>RE=Nd,RE=Nd时压铸镁合金具有最佳的综合拉伸性能。在Mg-3.5Al-RE镁合金中添加Zn和Mn元素后,镁合金中短棒状/鱼骨状Al_(11)Nd_(3)相明显较压铸Mg-3.5Al-3Nd镁合金少、颗粒状Al_(2)Nd相尺寸增大,室温拉伸性能与Mg-3.5Al-3Nd镁合金相当,显微硬度提高了7.02%,导热系数减小,流动长度增大。

关键词：压铸Mg-3.5Al-RE镁合金稀土元素显微组织流动性导热性力学性能

A Sequence-Scheduled and Query-Based MAC Protocol for Underwater Acoustic Networks with a Mobile Node

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Journal of Communications and Information Networks 2020年第2期5卷 150-159页

作者： Jing Huang cheng chi Wei Wang Haining Huang Institute of Acoustics Chinese Academy of SciencesBeijing 100190China Key Laboratory of Science and Technology on Advanced Underwater Acoustic Signal Processing Chinese Academy of SciencesBeijing 100190China University of chinese Academy of Sciences Beijing 100049China

Since mobile nodes such as autonomous underwater vehicles can effectively expand network coverage,underwater acoustic networks with mobile nodes have attracted more and more attention in recent *** ensure the timely access of a mobile node without disturbing the normal transmission of data packets from static nodes,a sequence-scheduled and query-based medium access control protocol is proposed in this *** underwater nodes with data packets to be transmitted reply with a control packet for channel reservation after receiving the broadcast control packet of the buoy,then the reserved nodes transmit their data packets as the order calculated by the *** develop a mechanism to adjust the transmission order of the control packets sent by the underwater nodes in the handshake phase to reduce the collision and guarantee the success rate of reservation,and a query is initiated when the reserved control packet of the mobile node is not received by the buoy in the handshake to respond to the data transmission request of the mobile node in *** show that the maximum nodal throughput of the proposed MAC protocol increases by at least 20%and the access delay of the mobile node decreases by about 90%,compared to the two reference ***,the average access probability of the mobile node in the proposed protocol is more than 90%.

关键词： sequence-scheduled query underwater acoustic networks mobile nodes MAC protocol

外周灌注指数联合APACHEⅡ评分预测脓毒性休克患者28天预后的价值

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内科理论与实践 2024年第3期19卷 174-179页

作者：巩皓迟骋张晓霞新疆医科大学第一附属医院急救重症监护室新疆乌鲁木齐830054 北京大学人民医院急诊科北京100044

目的:研究外周灌注指数(periphral perfusion index,PPI)联合急性生理与慢性健康评价Ⅱ(acute physi-ology and chronic evaluationⅡ,APACHEⅡ)评分对预测脓毒性休克患者预后的价值。方法:前瞻性纳入2023年1月至8月新疆医科大学第一附... 详细信息

目的:研究外周灌注指数(periphral perfusion index,PPI)联合急性生理与慢性健康评价Ⅱ(acute physi-ology and chronic evaluationⅡ,APACHEⅡ)评分对预测脓毒性休克患者预后的价值。方法:前瞻性纳入2023年1月至8月新疆医科大学第一附属医院急诊科确诊脓毒性休克患者200例,根据患者28 d预后情况分为存活组(84例)与死亡组(116例),记录患者姓名、年龄、性别、入院后生命体征、格拉斯哥昏迷评分量表(Glasgow coma scale,GCS)、脓毒症相关性器官功能衰竭评价(sepsis-related organ failure assessment,SOFA)、APACHEⅡ、感染部位、入院24 h补液量、抗菌药物使用情况、既往史、血管活性药物使用种类及24 h剂量、机械通气情况、血常规、肝功能、肾功能、凝血指标、发病时间、28 d预后结局等相关资料。分别测定2组患者入院即刻(0 h)、入院后6 h和入院后12 h的乳酸值及PPI值,并计算患者0~6 h、0~12 h乳酸清除率。利用COX回归筛选预测脓毒性休克患者预后的独立因素,绘制受试者操作特征曲线(receiver operator characteristic curve,ROC曲线),分析PPI参数联合APACHEⅡ评分预测患者预后的曲线下面积(area under the curve,AUC)。结果:与死亡组患者相比,存活组GCS评分、0 hPPI、6 hPPI、12 hPPI、0~12 h乳酸清除率较高,年龄、SOFA评分、APACHEⅡ评分、0 h乳酸、12 h乳酸较低(均P<0.05);COX回归发现12 hPPI为患者预后的独立预测因子,预测脓毒性休克患者预后AUC为0.945,12 hPPI联合预测APACHEⅡ评分预测患者预后AUC为0.996。结论:入院后12 h PPI联合APACHEⅡ评分对脓毒性休克患者28 d预后具有良好的预测价值。

关键词：外周灌注指数脓毒性休克 APACHEⅡ评分乳酸清除率预后

Highly reliable relative navigation for multi-UAV formation flight in urban environments

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chinese Journal of Aeronautics 2021年第7期34卷 257-270页

作者： Shizhuang WANG Xingqun ZHAN Yawei ZHAI cheng chi Jiawen SHEN School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai 200240China

Formation flight of multiple Unmanned Aerial Vehicles(UAVs)is expected to bring significant benefits to a wide range of *** and reliable relative position information is a prerequisite to safely maintain a fairly close distance between UAVs and to achieve inner-system collision ***,Global Navigation Satellite System(GNSS)measurements are vulnerable to erroneous signals in urban canyons,which could potentially lead to catastrophic ***,on the basis of performing relative positioning with double differenced pseudoranges,this paper develops an integrity monitoring framework to improve navigation integrity(a measure of reliability)in urban *** the one hand,this framework includes a fault detection and exclusion scheme to protect against measurement *** accommodate urban scenarios,spatial dependence in the faults are taken into consideration by this *** the other hand,relative protection level is rigorously derived to describe the probabilistic error bound of the navigation *** indicator can be used to evaluate collision risk and to warn collision danger in real *** proposed algorithms are validated by both simulations and flight *** results quantitatively reveal the sensitivity of navigation performance to receiver configurations and environmental *** experimental results suggest high efficiency and effectiveness of the new integrity monitoring framework.

关键词： Collision avoidance Formation flight Global Navigation Satellite System(GNSS) Integrity Relative navigation Unmanned Aerial Vehicle(UAV)

全民健身公共数据确权授权及使用的中国方案设计研究

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体育科学 2024年第4期44卷 89-96,F0003页

作者：张咪何元春池骋张政龙杨可鑫王丽娟哈尔滨体育学院研究生院黑龙江哈尔滨150008 厦门大学体育教学部福建厦门361005 厦门大学马克思主义学院福建厦门361005

数据确权授权是数据流通和共享的基础,但当下我国全民健身公共数据确权授权存在诸多困境。借助访谈、文本分析及案例研究等方法,结合劳动赋权论、“自物权-他物权”和“著作权-邻接权”及我国城乡土地制度改革中的土地所有权、承包权、... 详细信息

数据确权授权是数据流通和共享的基础,但当下我国全民健身公共数据确权授权存在诸多困境。借助访谈、文本分析及案例研究等方法,结合劳动赋权论、“自物权-他物权”和“著作权-邻接权”及我国城乡土地制度改革中的土地所有权、承包权、经营权的“三权”分置模式,基于“数据二十条”及全民健身公共数据特征的公共体育数据确权授权制度构建了中国方案。这对于明晰确权机构归属、权利主体及其主要权能和实现方式意义深远,也是助推“数据二十条”中纸面权利真正落地的应因之道。规制路径有:科学界定全民健身公共数据确权授权及使用中的法律概念;加强顶层设计,为全民健身公共数据确权授权路径建构“试制度、探新路”;明晰所有权、使用权和管理权,合理制定全民健身公共数据确权授权地方性行政法规;分类分级管理,确保全民健身公共数据安全、合规和有效利用;努力提升全民健身公共数据要素市场安全治理水平等。

关键词：全民健身公共数据确权授权中国方案

基于非负矩阵分解的双曲调频信号目标回波增强

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哈尔滨工程大学学报 2024年第7期45卷 1273-1279页

作者：崔小斌李淑秋李宇李子高孙飞虎迟骋金盛龙王冠群中国科学院声学研究所北京100190 中国科学院先进水下信息技术重点实验室北京100190 中国科学院大学北京100049

双曲调频信号是主动声呐中常用的多普勒不敏感信号。在实际使用中,由于信道变化和混响影响,目标回波较弱。针对水下航行器主动声呐探测性能下降问题,本文提出基于非负矩阵分解的双曲调频信号目标回波增强方法。该方法对目标回波和干扰... 详细信息

双曲调频信号是主动声呐中常用的多普勒不敏感信号。在实际使用中,由于信道变化和混响影响,目标回波较弱。针对水下航行器主动声呐探测性能下降问题,本文提出基于非负矩阵分解的双曲调频信号目标回波增强方法。该方法对目标回波和干扰信号的基矩阵分别定义,将发射信号的时频图作为目标回波的频率信息矩阵,对目标回波的时间信息矩阵做出约束,迭代处理完成目标回波的增强,获得较高增益的匹配回波检测结果。数值仿真和海上试验结果表明:本文方法与传统匹配滤波方法相比,其峰均比值提高了2 dB以上,提高了回波检测结果。

关键词：主动声呐水下探测混响噪声非负矩阵分解双曲调频信号回波增强目标检测

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Analysis of flow-sediment rating curve hysteresis based on flow and sediment travel time estimations

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International Journal of Sediment Research 2018年第2期33卷 171-182页

作者： chi-cheng Yang Kwan Tun Lee Water Resources Agency Department of River & Harbor Engineering National Taiwan Ocean University

A flow-sediment rating curve is used to describe the relation between flow discharge and suspendedsediment concentration for a specific location. Five types of flow-sediment rating curves-single-valued line, clockwise loop, counterclockwise loop, single-valued line plus loop, and figure eight-were found to rely on the flow and available sediment arriving at the measuring site. In this study, equations for flow and sediment travel time were derived according to soil, rainfall, and watershed geomorphologic characteristics. The hysteresis of the rating curve was related to the travel times by a series of numerical *** data collected from the Goodwin Creek Experimental Watershed, Mississippi, United States were used to verify the proposed rating curve hysteresis analysis. The results indicate that when the flow travel time is more extended than the sediment travel time, the rating curve shows a clockwise loop. A counterclockwise loop in the rating curve shows that the flow travel time is less extended than the sediment travel time. If the flow travel time exceeds the sediment travel time in specific runoff states and is less than the sediment travel time in other runoff states, then a single line plus a loop rating curve or a figure-eight rating curve is observed. The criterion for the model parameters to obtain equalization of the flow and sediment travel times was derived, which can identify the type of flow-sediment rating curve in a specific watershed.

关键词： Flow-sediment rating curve Flow travel time Sediment travel time Instantaneous unit sedimentgraph Kinematic wave Geomorphologic IUH

Long-term survival outcome of laparoscopic liver resection for hepatocellular carcinoma

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World Journal of Gastrointestinal Surgery 2021年第10期13卷 1110-1121页

作者： Shi Lam Kai-chi cheng Department of Surgery Kwong Wah HospitalHong Kong999077China

Long-term survival is the most important outcome measurement of a curative oncological *** hepatocellular carcinoma(HCC),the long-term disease-free and overall survival of laparoscopic liver resection(LLR)is shown to be non-inferior to the current standard of open liver resection(OLR).Some studies have reported a superior long-term oncological outcome in LLR when compared to *** has been argued that improvement of visualization and instrumentation and reduced operative blood loss and perioperative blood transfusion may contribute to reduced risk of postoperative tumor *** the other hand,since most of the comparative studies of the oncological outcomes of LLR and OLR for HCC are non-randomized,it remained inconclusive as to whether LLR confers additional survival benefit compared to *** the paucity of level 1 evidence,the practice of LLR for HCC has gained wide-spread acceptance due to the reproducible improvements in the perioperative outcomes and non-inferior oncological outcomes demonstrated by large-scaled,matched comparative ***-analyses of the outcomes of these studies by multiple systematic reviews have also returned noncontradictory *** the basis of a theoretical advantage of LLR over OLR in preventing tumor recurrence,the current review aims to dissect from the current meta-analyses and comparative studies any evidence of such superiority.

关键词： Hepatocellular carcinoma Laparoscopic hepatectomy Liver resection Longterm outcome Overall survival Disease-free survival

Laparoscopic liver resection: western versus eastern experience

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chinese Journal of Cancer Research 2014年第3期26卷 243-244页

作者： Fiona KM Chan Kai chi cheng Department of Surgery Kwong Wah Hospital

Hepatocellular carcinoma （HCC） is the most common primary liver tumor. It is the seventh world＇s most common cancer and rank second of all cancer deaths （I）. It incurs a global health burden, with 782,451 new cases diagnosed worldwide in the year 2012 and a morality of 745,517： a high incidence to morality ratio of 1.05. Majority of patients resides in the developing world and often presented late resulting in poor prognosis. Early detection is thus crucial for capturing early disease whereby curative resection can offer the best survival outcome （2）.

关键词： HCC western versus eastern experience