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Multiple UAVs cooperative formation forming control based on back-stepping-like approach

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Journal of Systems Engineering and Electronics 2018年第4期29卷 816-822页

作者： ZHANG Liang LU Yi xu shida FENG Han Aeronautical Engineering College Air Force Engineering University

To ensure multiple unmanned aerial vehicles （UAVs）reach stable formation quickly, a cooperative guidance law basedon the back-stepping-like approach is designed in this *** the guidance mechanism of virtue leader vehicle, thedynamic equation of tracking errors for each UAV is built. Thecommunication interactive relationships are described based ongraph theory, and the guidance law for formation reaching is ob-tained by the back-stepping-like approach. The formation stabilityis analyzed by constructing an appropriate Lyapunov function. Thesimulation results have shown that this guidance and control lawcan make each UAV converge to the trajectory of the virtue leaderultimately, and has the quicker rate of convergence and lowertracking error.

关键词： unmanned aerial vehicle (UAV) formation reaching guidance law stability.

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基于改进YOLOv5的轴承表面缺陷检测

组合机床与自动化加工技术 2024年第6期 166-170页

作者：吴迪于正林徐式达周斌邵长顺长春理工大学机电工程学院长春130022 长春理工大学重庆研究院重庆401135

传统的轴承表面缺陷检测由于缺陷目标较小,错检漏检率高,检测效率低等问题,为此提出一种基于YOLOv5网络改进的算法模型。首先,在主干网络中添加高效通道注意力机制(efficient channel attention, ECA),增强网络的特征提取能力,集中关注... 详细信息

传统的轴承表面缺陷检测由于缺陷目标较小,错检漏检率高,检测效率低等问题,为此提出一种基于YOLOv5网络改进的算法模型。首先,在主干网络中添加高效通道注意力机制(efficient channel attention, ECA),增强网络的特征提取能力,集中关注各种影响轴承质量的重点信息;其次,在YOLOv5网络基础上添加小目标检测层,通过补充融合特征层和引入额外检测头,提高网络对小目标缺陷检测的精度;最后,在特征融合网络中,融入简化后的加权双向特征金字塔网络(bidirectional feature pyramid network, BiFPN),在不增加较多计算成本的基础上,更好地实现多尺度特征融合。在构建的深沟球轴承表面缺陷数据集上的实验结果表明,相比于原YOLOv5s模型,精确率、召回率、平均精度分别提高了5.8%、2.4%、5.3%,检测速度为71 f/s,满足工业大批量检测的要求。

关键词： YOLOv5 缺陷检测注意力机制小目标检测层简化BiFPN

Experimental investigation on n-decane plasma cracking in an atmospheric-pressure argon environment

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Plasma Science and Technology 2019年第8期21卷 74-81页

作者： shida xu Di JIN Feilong SONG Yun WU Science and Technology on Plasma Dynamics Laboratory Air Force Engineering UniversityXi’an710038People’s Republic of China Institute of Aeroengine Xi’an Jiaotong UniversityXi’an710049People’s Republic of China Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department ofEnergy and Power EngineeringTsinghua UniversityBeijing100084People’s Republic of China

In order to solve the problem of the difficulty of igniting and steadily propagating a continuous rotating detonation engine when using liquid hydrocarbon fuel, an experiment was carried out using a dielectric barrier discharge excited by a nanosecond power supply to crack n-decane, the single alternative fuel to aviation kerosene, in a pre-heated argon *** changing the voltages and the discharge frequencies, the concentrations of different components as well as a number of different species were *** generating mechanism of olefins and alkanes together with their competition mechanism were *** influence of the voltage on isomer products was also *** results demonstrate that the bond energy distribution and the species generating condition are the main factors affecting the formation of the *** the increasing of voltage and discharge frequency, small molecule olefins, large molecular olefins, large molecular alkanes, small molecular alkanes, and hydrogen were detected, and in turn, their concentrations were also increased except for ethylene;what is more, when the voltage was increased over 8.5 kV, the n-butene converted to trans-butene, and the n-pentene converted to isoamylene.

关键词： dielectric barrier discharge plasma cracking n-decane isomer

Experimental investigation on DBD plasma reforming hydrocarbon blends

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Plasma Science and Technology 2021年第8期23卷 175-187页

作者： shida xu Yun WU Feilong SONG Xin CHEN Di JIN Science and Technology on Plasma Dynamics Laboratory Air Force Engineering UniversityXi'an 710038People's Republic of China Institute of Aeroengine Xi'an Jiaotong UniversityXi'an 710049People's Republic of China

To improve the‘detonation-supporting’performance of fuel-rich catalytic combustion products,DBD plasma,stimulated by adjustable nanosecond pulse power supply,was used to further regulate the components and concentrations of the hydrocarbon *** this paper,the parameters including load voltage,frequency,rising(falling)edge,pulse width and feeding flow rate were changed respectively,and the corresponding concentration and proportion change of the components in blend gas were *** to the experiment result,it was found that when the discharge frequency is low,the plasma mainly promotes the transformation of light gaseous substances,while it mainly promotes the conversion to heavy hydrocarbons when the frequency is *** load voltage will strengthen this *** controlling and reforming effect of plasma on the blend gas will decrease with the increase of voltage rising(falling)edge and the feeding flow *** regulation effect will be strengthened with the increase of pulse width under 200 *** the increase of discharge intensity,the‘carbon’settles on the walls of the reactor,which will change the dielectric constant,leading to the loss of control of the discharge.

关键词： hydrocarbon blends DBD plasma reforming carbon deposition

多序列MRI对高血压性脑出血的诊断价值分析

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医学影像学杂志 2024年第6期34卷 1-4页

作者：徐世达陈钟杰韩倩倩雷新军浙江中医药大学附属丽水中医院放射科浙江丽水323020 浙江省丽水市第二人民医院放射科浙江丽水323000

目的探讨多序列MRI对高血压性脑出血的诊断价值。方法选取134例疑似高血压性脑出血患者,所有患者入院后均接受多序列磁共振成像(MRI)和头颅电子计算机断层扫描(CT)检查,以CT检查结果为依据,分析多序列MRI对高血压性脑出血的诊断效能及... 详细信息

目的探讨多序列MRI对高血压性脑出血的诊断价值。方法选取134例疑似高血压性脑出血患者,所有患者入院后均接受多序列磁共振成像(MRI)和头颅电子计算机断层扫描(CT)检查,以CT检查结果为依据,分析多序列MRI对高血压性脑出血的诊断效能及其诊断脑出血部位与头颅CT检查结果的一致性。结果头颅CT检查结果显示,134例疑似高血压性脑出血患者中确诊高血压性脑出血114例,其中基底节出血50例,丘脑出血13例,脑叶出血35例,小脑出血10例,脑室出血6例。以头颅CT检查结果为参照,多序列MRI诊断高血压性脑出血的准确度为92.54%(124/134),灵敏度为96.49%(110/114),特异度为70.00%(14/20)。多序列MRI诊断脑出血部位与头颅CT诊断结果的一致性较高(Kappa=0.787,P<0.001)。结论多序列MRI诊断高血压性脑出血具有良好的准确性,且其诊断脑出血部位与头颅CT诊断结果具有较高的一致性。

关键词：高血压性脑出血磁共振成像多序列扫描体层摄影术,X线计算机

Graceful Labelings of the Cycles with a Chord

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上饶师范学院学报 1991年第5期 25-31+36页

作者： xu shida

A cycle with a chord C′is a cycle Cplus one edge joiningtwo nonadjacent *** 1977,***,*** and *** proposed thefollowin g *** The cycles with a chord are *** was proved in [2] that conjecture is true if the distancein ... 详细信息

关键词： Th Graceful Labelings of the Cycles with a Chord

基于指数函数的川滇地区余震序列衰减规律研究

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地震工程学报 2024年第1期46卷 207-213页

作者：徐世达段俊康何本国刘佳奇鲍泽铭陈天晓东北大学深部金属矿山安全开采教育部重点实验室辽宁沈阳110819

较大的余震可能造成额外损失并有二次触发建筑物受灾的风险。为研究余震序列衰减规律,文章尝试采用指数衰减模型拟合分析5个不同地区余震序列,并借助修正赤池信息准则、贝叶斯信息准则与调整后R^(2),分析其与传统余震衰减模型的性能。... 详细信息

较大的余震可能造成额外损失并有二次触发建筑物受灾的风险。为研究余震序列衰减规律,文章尝试采用指数衰减模型拟合分析5个不同地区余震序列,并借助修正赤池信息准则、贝叶斯信息准则与调整后R^(2),分析其与传统余震衰减模型的性能。结果表明,指数模型描述余震序列衰减规律的能力与修正的大森余震模型、修正的拉伸指数模型接近。尤其对于四川长宁M_(S)6.0余震序列和云南彝良M_(S)5.7余震序列,指数模型表现优于其他两种模型。指数模型参数具有明确的物理意义:参数A与r之和能够准确代表强震后的实际初始余震数,5个余震序列初始余震数偏差均小于1.70%;参数k可作为反映余震序列衰减快慢的特征值,k值越大则余震序列衰减越慢,其值与主震震级呈反比例关系。

关键词：余震序列指数函数初始余震数衰减

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集料化学特性对C-S-H成核和生长的影响

硅酸盐学报 2021年第5期49卷 972-979页

作者：欧阳小伟许世达马玉玮叶光广州大学广州大学–淡江大学工程结构灾害与控制联合研究中心广州510006 Faculty of Civil Engineering and Geosciences Delft University of Technology2628 CN DelftThe Netherlands

探究集料化学特性对水化硅酸钙(C-S-H)成核和生长的影响及其作用机理对集料优选和性能改善意义重大。选用石灰石、石英石和菱镁石为研究对象,通过测量3种集料的粉末颗粒在模拟溶液中的zeta电位,研究了集料表面与模拟溶液中离子间的相互... 详细信息

探究集料化学特性对水化硅酸钙(C-S-H)成核和生长的影响及其作用机理对集料优选和性能改善意义重大。选用石灰石、石英石和菱镁石为研究对象,通过测量3种集料的粉末颗粒在模拟溶液中的zeta电位,研究了集料表面与模拟溶液中离子间的相互作用;采用扫描电子显微镜观察了C-S-H在这些集料表面的成核和生长。采用水化热的方法,研究了集料的化学特性对水泥早期水化的影响。结果表明:石灰石表面对Ca^(2+)有极强的吸附作用(化学吸附),这使得C-S-H在石灰石表面成核密度高且生长具有方向性,从而极大地促进了水泥的水化;石英石表面通过静电力作用吸附Ca^(2+),该作用弱于化学吸附作用,从而使得C-S-H在石英石表面成核密度低,且呈无序和稀疏分布;菱镁石对Ca^(2+)的吸附作用最弱而对SO_(4)^(2-)具有很强的吸附作用,这使得C-S-H在菱镁石表面成核密度最低,从而减缓了水泥的早期水化。

关键词：石灰石石英石水化硅酸钙 zeta电位水化集料水泥

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基于便携式地质雷达的巷道围岩松动圈探测

中国矿业 2019年第11期28卷 99-103页

作者：徐世达陈治洋雷刚东北大学深部金属矿山安全开采教育部重点试验室

基于便携式雷达探测技术和声波测试技术,研究了阿舍勒铜矿深部采区不同中段、开采扰动前后的巷道围岩松动圈厚度分布规律。研究结果表明:采用Sub Surface Profiler(SSP)新型便携式雷达探测的巷道围岩松动圈厚度与采用声波测试的巷道围... 详细信息

基于便携式雷达探测技术和声波测试技术,研究了阿舍勒铜矿深部采区不同中段、开采扰动前后的巷道围岩松动圈厚度分布规律。研究结果表明:采用Sub Surface Profiler(SSP)新型便携式雷达探测的巷道围岩松动圈厚度与采用声波测试的巷道围岩松动圈厚度基本一致,采用SSP便携式地质雷达能够快速、准确地探测巷道围岩的松动圈厚度。阿舍勒铜矿-200 m中段巷道围岩松动圈厚度为1.6~1.9 m,明显大于50 m中段开采扰动前的巷道围岩松动圈厚度。开采扰动明显加深了采场临近巷道围岩松动圈厚度,阿舍勒铜矿50 m中段开采扰动前,临近采场巷道围岩松动圈厚度为1.4~1.7 m,开采扰动后为1.6~2.0 m。研究成果对矿山依据围岩松动圈厚度优化支护参数具有重要参考价值。

关键词：巷道松动圈厚度便携式地质雷达开采扰动