检索结果-南通市图书馆

A Dual-Cluster-Head Based Medium Access Control for Large-Scale UAV Ad-Hoc Networks

在线全文

学校读者我要写书评

暂无评论

China Communications 2024年第5期21卷 123-136页

作者： Zhao Xinru Wei Zhiqing Zou Yingying ma hao Cui Yanpeng Feng Zhiyong Key Laboratory of Universal Wireless Communications Ministry of EducationSchool of Information and Communication EngineeringBeijing University of Posts and TelecommunicationsBeijing100876China

Unmanned Aerial Vehicle(UAV)ad hoc network has achieved significant growth for its flexibility,extensibility,and high deployability in recent *** application of clustering scheme for UAV ad hoc network is imperative to enhance the performance of throughput and energy *** conventional clustering scheme,a single cluster head(CH)is always assigned in each ***,this method has some weaknesses such as overload and premature death of CH when the number of UAVs *** order to solve this problem,we propose a dual-cluster-head based medium access control(DCHmaC)scheme for large-scale UAV *** DCHmaC,two CHs are elected to manage resource allocation and data forwarding ***,two CHs work on different *** of CH is used for intra-cluster communication and the other one is for inter-cluster communication.A markov chain model is developed to analyse the throughput of the *** result shows that compared with FM-maC(flying ad hoc networks multi-channel maC,FM-maC),DCHmaC improves the throughput by approximately 20%~50%and prolongs the network lifetime by approximately 40%.

关键词： dual cluster head medium access control UAV swarm

Experimental research on the launching system of auxiliary charge with filter cartridge structure

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第1期31卷 41-48页

作者： Zi-Jun Chen Ze He Hong-hao ma Lu-Qing Wang Zhao-Wu Shen CAS Key Laboratory of Mechanical Behavior and Design of materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefeiAnhui230027PR China State Key Laboratory of Fire Science University of Science and Technology of ChinaHefeiAnhui230026PR China

A launching system with a filter cartridge structure was proposed to improve the muzzle velocity of the *** combustion chamber of the launching system is divided into two fixed chambers,one is located in the breech chamber,and the other is arranged in the *** breech chamber charge was ignited first,and the charges in the auxiliary chambers were ignited by the high-temperature,highpressure combustible gas trailing the *** this way,the combustible gas in the auxiliary chambers could compensate for the pressure drop caused by the movement of the *** proposed device features the advantage of launching a projectile with high muzzle velocity without exceeding the maximum pressure in the *** order to obtain some internal ballistic characteristics of the launch system,some critical structure,such as the length of the filter cartridge auxiliary charge,the combustion degree of the propellant in the chamber,and the length of the barrel,are *** experimental results show that with the increased auxiliary charge length,a pressure plateau or even a secondary peak pressure can be formed,which is less than the peak *** projectile velocity increased by 23.57%,14.64%,and 7.65%when the diaphragm thickness was 0 mm,1 mm,and2 mm,*** muzzle velocity of the projectile can be increased by 13.42%by increasing the length of the *** the same charge condition,with the increase of barrel length,the energy utilization rate of propellant increases by 28.64%.

关键词： Interior ballistics Charge structures Launch system Charge design

Enhanced red luminescence of Ca_(3)Si_(2−x)M_(x)O_(7):Eu^(3+)(M=Al,P)phosphors via partial substitution of Si^(4+) for applications in white light-emitting diodes

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第2期43卷 736-748页

作者： Yu-hao ma Xi Gao Wen-Tao Zhang Zhen-Rui Yang Zhou Zhao Chen Qu College of materials and Chemistry and Chemical Engineering Chengdu University of TechnologyChengdu610059China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu610059China International Advanced Energy Science Research and Education Center Graduate School of Energy ScienceKyoto UniversityYoshida-HonmachiKyoto606-8501Japan

A red-emitting phosphor Ca_(2.91)Si_(2)O_(7):0.09Eu^(3+) with partial Al^(3+)/P^(5+) substitution on Si^(4+) was synthesized via a simple solid-state method,and the effects of the introduction of the M^(3+/5+)(M=Al,P)ions on the crystal structure and photoluminescence performance of Ca_(2.91)Si_(2−x)M_(x)O_(7):0.09Eu^(3+) phosphors were *** X-ray diffraction(XRD),energy-dispersive X-ray spectroscopy(EDS),and X-ray photoelectron spectroscopy(XPS)results revealed that the structure of Ca_(3)Si_(2)O_(7) remained the same after the introduction of Al^(3+) and P^(5+) *** characteristic emission of Eu^(3+)-doped Ca_(3)Si_(2−x)M_(x)O_(7) phosphors exhibited two main peaks at 617 nm(red)and 593 nm(orange)under excitation at 394 nm,which originated from the^(5)D_(0)→^(7)F_(2)and^(5)D_(0)→^(7)F_(1) electron transitions of Eu^(3+) *** the partial substitution of Al^(3+) and P^(5+),the red emission intensities of the Ca_(2.91)Si_(2)O_(7):0.09Eu^(3+) phosphors were significantly enhanced by 1.88-and 1.42-fold,respectively,which is attributed to the crystal-field effect around Eu^(3+).Meanwhile,the luminescence intensities of the Ca_(2.91)Si_(1.96)Al_(0.04)O_(7):0.09Eu^(3+) and Ca_(2.91)Si_(1.94)P_(0.06)O_(7):0.09Eu^(3+) phosphors at 210℃ were 79.36%and 77.53%of those at 30°C,respectively,indicating their excellent thermal ***,the as-prepared Ca_(2.91)Si_(1.96)Al_(0.04)O_(7):0.09Eu^(3+)and Ca_(2.91)Si_(1.94)P_(0.06)O_(7):0.09Eu^(3+) red-emitting phosphors were combined with a near-ultraviolet chip of 395 nm to fabricate red-light-emitting diode(LED)and white(w)-LED devices with excellent chromaticity *** summary,Al^(3+)/P^(5+)-substituted Ca_(2.91)Si_(2)O_(7):0.09Eu^(3+) can serve as red-emitting phosphors for applications in w-LEDs.

关键词： Ca_(3)Si_(2)O_(7) Red-emitting phosphor Structure substitution Luminescence enhancement Crystal-field effect White light-emitting diode

Optical responses of metallic plasmonic arrays under the localized excitation

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第3期17卷 1571-1577页

作者： Sen Yan hao ma Yi-Fan Bao maofeng Cao Chuan Liu Kaifeng Zhang Xiaowei Wu Jianbo He Xiang Wang Bin Ren State Key Laboratory of Physical Chemistry of Solid Surfaces Department of ChemistryCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Innovation Laboratory for Sciences and Technologies of Energy materials of Fujian Province(IKKEM) Xiamen 361005China Research&Development Group HitachiLtd.Yokohama 244-0817KanagawaJapan Department of Electronic Science and Engineering Kyoto UniversityKyoto 615-8510Japan

The metallic plasmonic array that can support both propagating surface plasmon polaritons(PSPPs)and localized surface plasmon resonance(LSPR)possesses rich optical properties and remarkable optical performance,making it a powerful platform for applications in photonics,chemistry,and *** practical applications,the excitation spot is usually smaller than the area of metal *** is thus imperative to address“how many array units are enough?”towards a rational design of plasmonic ***,we employed focused ion beam(FIB)to precisely fabricate a series of plasmonic array structures with increased unit *** utilizing photoluminescence(PL)and surface-enhanced Raman spectroscopy(SERS),we found that the array units outside the excitation spot still have a significant impact on the optical response within the *** with the numerical simulation,we found that the boundary of the finite array leads to the loss of PSPP outside the excitation point,which subsequently affects the coupling of PSPP and LSPR in the excitation spot,leading to variations in PL and SERS *** on the findings,we further tuned the LSPR mode of the metal arrays by electrodeposition to obtain strong near-field enhancement without any influence on the PSPP *** work advances the understanding of near-field and far-field optical behavior in finite-size array structures and provides guidance for designing highly-efficient photonic devices.

关键词： plasmonic periodic array finite-size effects dark field scattering surface-enhanced Raman spectroscopy(SERS)

Loneliness,social isolation and incident chronic kidney disease among patients with diabetes

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

General Psychiatry 2024年第3期37卷 440-448页

作者： Rui Tang Jian Zhou Xuan Wang hao ma Xiang Li Yoriko Heianza Lu Qi Epidemiology Tulane University School of Public Health and Tropical MedicineNew OrleansLouisianaUSA The Second Xiangya Hospital of Central South University ChangshaHunanChina Nutrition Harvard University T H Chan School of Public HealthBostonMassachusettsUSA

Background Individuals with diabetes have a significantly higher risk of developing chronic kidney disease(CKD)and higher levels of social isolation and loneliness compared with those without ***,the American Heart Association highlighted the importance of considering social determinants of health(SDOH)in conjunction with traditional risk factors in patients with *** To investigate the associations of loneliness and social isolation with incident CKD risk in patients with diabetes in the UK *** A total of 18972 patients with diabetes were included in this prospective *** and Social Isolation Scales were created based on self-reported *** adjusted Cox proportional hazard model was used to investigate the associations of loneliness and social isolation with CKD risk among patients with *** relative importance in predicting CKD was also calculated alongside traditional risk *** During a median follow-up of 10.8 years,1127 incident CKD cases were reported.A higher loneliness scale,but not social isolation,was significantly associated with a 25%higher risk of CKD,independent of traditional risk factors,among patients with *** the individual loneliness factors,the sense of feeling lonely emerged as the primary contributing factor to the elevated risk of *** with individuals not experiencing feelings of loneliness,those who felt lonely exhibited a 22%increased likelihood of developing *** addition,feeling lonely demonstrated greater relative importance of predicting CKD compared with traditional risk factors such as body mass index,smoking,physical activity and *** This study indicates the significant relationship between loneliness and CKD risk among patients with diabetes,highlighting the need to address SDOH in preventing CKD in this population.

关键词： patients diabetes kidney

基于外差相敏色散光谱技术的宽动态范围甲烷气体检测

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国光学（中英文） 2024年第4期17卷 789-800页

作者：周晨马柳昊王宇武汉理工大学汽车工程学院湖北武汉430070 中国科学院长春光学精密机械与物理研究所应用光学国家重点实验室吉林长春130033

为实现痕量甲烷气体的宽动态范围高灵敏度检测,本文开展了双边带拍频抑制模式的外差相敏色散光谱技术研发,研究了电光调制器工作特性以及偏置电压调控方法,对比了抑制与非抑制模式下的色散相位谱轮廓与信噪比,并对检测性能(如线性动态... 详细信息

为实现痕量甲烷气体的宽动态范围高灵敏度检测,本文开展了双边带拍频抑制模式的外差相敏色散光谱技术研发,研究了电光调制器工作特性以及偏置电压调控方法,对比了抑制与非抑制模式下的色散相位谱轮廓与信噪比,并对检测性能(如线性动态检测范围)进行了系统研究。基于近红外分布式反馈激光器和电光调制器,搭建了外差相敏色散甲烷气体检测系统,通过探索和分析电光调制器的最佳工作区间,实现了双边带拍频抑制进而得到了大幅值、高信噪比的色散相位信号。测量了典型高频(1.2 GHz)强度调制下甲烷/氮气标气的色散相位信号,获取了色散相位信号峰峰值随气体浓度的变化规律。同时开展了波长调制光谱技术实验,对两种技术的线性度、检测动态范围和对光功率波动的抗干扰性能进行对比研究。最后,通过测量不同浓度的标气验证了该系统在宽动态、快速时间响应下的性能。所开发的基于外差相敏色散光谱技术的甲烷检测系统具有线性度高(R^(2)=0.9999),动态检测范围宽(38.5 ppm~40%),且对光功率波动免疫性高的显著优势。本文研发的基于外差相敏色散光谱技术的气体检测技术在宽动态范围检测和实际现场检测应用领域具有广阔的前景。

关键词：相敏检测色散光谱双边带拍频抑制甲烷检测宽动态范围

维普期刊数据库博看期刊

在线全文

学校读者我要写书评

暂无评论

一种多层多模态融合3D目标检测方法

电子学报 2024年第3期52卷 696-708页

作者：周治国马文浩北京理工大学集成电路与电子学院北京100081

在自动驾驶感知系统中视觉传感器与激光雷达是关键的信息来源,但在目前的3D目标检测任务中大部分纯点云的网络检测能力都优于图像和激光点云融合的网络,现有的研究将其原因总结为图像与雷达信息的视角错位以及异构特征难以匹配,单阶段... 详细信息

在自动驾驶感知系统中视觉传感器与激光雷达是关键的信息来源,但在目前的3D目标检测任务中大部分纯点云的网络检测能力都优于图像和激光点云融合的网络,现有的研究将其原因总结为图像与雷达信息的视角错位以及异构特征难以匹配,单阶段融合算法难以充分融合二者的特征.为此,本文提出一种新的多层多模态融合的3D目标检测方法:首先,前融合阶段通过在2D检测框形成的锥视区内对点云进行局部顺序的色彩信息(Red Green Blue,RGB)涂抹编码;然后将编码后点云输入融合了自注意力机制上下文感知的通道扩充PointPillars检测网络;后融合阶段将2D候选框与3D候选框在非极大抑制之前编码为两组稀疏张量,利用相机激光雷达对象候选融合网络得出最终的3D目标检测结果.在KITTI数据集上进行的实验表明,本融合检测方法相较于纯点云网络的基线上有了显著的性能提升,平均maP提高了6.24%.

关键词：自动驾驶多传感器融合 3D目标检测点云编码自注意力机制

同方期刊数据库

双有源桥串联欠谐振变换器的最小回流电流控制

在线全文

学校读者我要写书评

暂无评论

电工技术学报 2024年第14期39卷 4480-4494页

作者：高祎韩周子航张欣马皓浙江大学电气工程学院杭州310027 浙江大学杭州国际科创中心杭州310027 浙江大学伊利诺伊大学厄巴纳香槟校区联合学院海宁311200

该文采用时域分析法对双有源桥串联欠谐振电路进行了分析,得到电感电流在稳态时的表达式并推导所有开关管实现软开关的条件。由于电压增益偏离1时仅采用移相控制难以实现所有开关管的软开关,因此,该文在传统移相控制的基础上,引入额外... 详细信息

该文采用时域分析法对双有源桥串联欠谐振电路进行了分析,得到电感电流在稳态时的表达式并推导所有开关管实现软开关的条件。由于电压增益偏离1时仅采用移相控制难以实现所有开关管的软开关,因此,该文在传统移相控制的基础上,引入额外的变频控制策略,使得电路在不同的电压增益和负载条件下都能有较好的软开关性能。然而,软开关的实现会增加电路的回流电流,影响电路的传输效率。该文对所提出的变频移相控制进行了进一步的优化,使其可以在确保电路实现软开关的同时产生最小的回流电流和电感电流有效值。所提出的控制策略在一台2 kW的样机中进行了验证。

关键词：双有源桥串联欠谐振变换器软开关最小回流电流控制变频控制

员工企业社会责任感知对于其建言行为的影响:解释水平理论视角

在线全文

学校读者我要写书评

暂无评论

中南大学学报（社会科学版） 2024年第4期30卷 119-131页

作者：颜爱民马浩中南大学商学院湖南长沙410083

基于解释水平理论,通过对503份三时点领导员工上下级配对数据的实证研究,分析了员工的企业社会责任感知如何通过提高员工解释水平从而促进其建言行为,并进一步验证了任务多样性的调节效应。回归分析结果表明:员工企业社会责任感知对于... 详细信息

基于解释水平理论,通过对503份三时点领导员工上下级配对数据的实证研究,分析了员工的企业社会责任感知如何通过提高员工解释水平从而促进其建言行为,并进一步验证了任务多样性的调节效应。回归分析结果表明:员工企业社会责任感知对于员工建言行为有显著正向影响;解释水平在企业社会责任感知与建言行为之间发挥部分中介作用;任务多样性正向调节了企业社会责任感知通过解释水平积极影响员工建言行为的间接效应。

关键词：解释水平理论企业社会责任感知建言行为任务多样性解释水平