期刊文献+

二次检索

题名
关键词
文摘
作者
第一作者
机构
刊名
分类号
参考文献
作者简介
基金资助
栏目信息
共找到266篇文章
< 1 2 14 >
每页显示 20 50 100
Downlink Resource Allocation for NOMA-Based Hybrid Spectrum Access in Cognitive Network 被引量:2
1
作者 Yong Zhang Zhenjie Cheng +3 位作者 Da Guo Siyu Yuan Tengteng Ma Zhenyu Zhang 《China Communications》 SCIE CSCD 2023年第9期171-184,共14页
To solve the contradiction between limited spectrum resources and increasing communication demand,this paper proposes a wireless resource allocation scheme based on the Deep Q Network(DQN)to allocate radio resources i... To solve the contradiction between limited spectrum resources and increasing communication demand,this paper proposes a wireless resource allocation scheme based on the Deep Q Network(DQN)to allocate radio resources in a downlink multi-user cognitive radio(CR)network with slicing.Secondary users(SUs)are multiplexed using non-orthogonal multiple access(NOMA).The SUs use the hybrid spectrum access mode to improve the spectral efficiency(SE).Considering the demand for multiple services,the enhanced mobile broadband(eMBB)slice and ultrareliable low-latency communication(URLLC)slice were established.The proposed scheme can maximize the SE while ensuring Quality of Service(QoS)for the users.This study established a mapping relationship between resource allocation and the DQN algorithm in the CR-NOMA network.According to the signal-to-interference-plusnoise ratio(SINR)of the primary users(PUs),the proposed scheme can output the optimal channel selection and power allocation.The simulation results reveal that the proposed scheme can converge faster and obtain higher rewards compared with the Q-Learning scheme.Additionally,the proposed scheme has better SE than both the overlay and underlay only modes. 展开更多
关键词 cognitive network network slicing non-orthogonal multiple access hybrid spectrum access resource allocation deep reinforcement learning
下载PDF
Optimal Energy-Efficient Transmission for Hybrid Spectrum Sharing in Cooperative Cognitive Radio Networks 被引量:9
2
作者 Linna Hu Rui Shi +3 位作者 Minghe Mao Zhiyu Chen Hongxi Zhou Weiliang Li 《China Communications》 SCIE CSCD 2019年第6期150-161,共12页
In order to improve the energy efficiency(EE)in cognitive radio(CR),this paper investigates the joint design of cooperative spectrum sensing time and the power control optimization problem for the secondary user syste... In order to improve the energy efficiency(EE)in cognitive radio(CR),this paper investigates the joint design of cooperative spectrum sensing time and the power control optimization problem for the secondary user systems to achieve the maximum energy efficiency in a cognitive network based on hybrid spectrum sharing,meanwhile considering the maximum transmit power,user quality of service(QoS)requirements,interference limitations,and primary user protection.The optimization of energy efficient sensing time and power allocation is formulated as a non-convex optimization problem.The Dinkelbach’s method is adopted to solve this problem and to transform the non-convex optimization problem in fractional form into an equivalent optimization problem in the form of subtraction.Then,an iterative power allocation algorithm is proposed to solve the optimization problem.The simulation results show the effectiveness of the proposed algorithms for energy-efficient resource allocation in the cognitive network. 展开更多
关键词 cognitive radio networks COOPERATIVE spectrum SENSING ENERGY-EFFICIENCY hybrid spectrum sharing power control SENSING time optimization
下载PDF
Optimal energy-efficiency capacity and sensing tradeoff for hybrid spectrum sharing in CRN 被引量:1
3
作者 QIU Tao XU Wen-jun +2 位作者 SONG Tae HE Zhi-qiang TIAN Bao-yu 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2012年第2期1-8,共8页
This paper investigates the tradeoff between energy-efficiency capacity and spectrum sensing under hybrid spectrum sharing model, where the spectrum sharing method is based on sensing results of secondary user (SU).... This paper investigates the tradeoff between energy-efficiency capacity and spectrum sensing under hybrid spectrum sharing model, where the spectrum sharing method is based on sensing results of secondary user (SU). The metric 'bits per joule', which captures the effect of energy overhead in spectrum sensing, is adopted to evaluate energy-efficiency capacity. We first formulize the tradeoff between energy-efficiency capacity and spectrum sensing as an optimization problem with mixture constraint of sensing time and detection threshold. Under some certain condition on the domain of detection threshold, i.e. in which we can't improve energy-efficiency capacity through increasing the detection probability, the original optimization problem can be reduced to a new unconstrained one, which only relates to sensing time. Then the existence and uniqueness of optimal sensing time to achieve maximum energy-efficiency capacity are discussed and a low-complexity algorithm is proposed to obtain the optimal solution. Finally, numerical simulation is performed to verify the theoretical analysis results. The simulation results indicate that hybrid spectrum sharing is remarkably beneficial to energy-efficient transmission in cognitive radio networks (CRN). And the proposed algorithm can quickly converge to the optimal solution. 展开更多
关键词 energy-efficiency capacity spectrum sensing hybrid spectrum sharing cognitive radio network (CRN)
原文传递
Performance Analysis of Wireless Mobile Radio Hybrid(DS/FH) Spread Spectrum Network
4
作者 余晓刚 王华 匡镜明 《Journal of Beijing Institute of Technology》 EI CAS 2004年第1期10-14,共5页
By the flexible redefinition of frequency-occupation and frequency-collision event, the frequency-(collision) probability of hybrid(DS/FH) spread spectrum network is analyzed. This probability is based on the simultan... By the flexible redefinition of frequency-occupation and frequency-collision event, the frequency-(collision) probability of hybrid(DS/FH) spread spectrum network is analyzed. This probability is based on the simultaneous transmission number threshold and is discussed in synchronous and asynchronous circumstances respectively. And then, the network throughput based on the packet correct reception probability is analyzed. Two models which have finite and infinite population respectively is discussed. At last, the numerical results are given. 展开更多
关键词 hybrid spread spectrum NETWORK frequency-collision probability THROUGHPUT
下载PDF
Analysis of Charge-Exchange Spectrum during Lower Hybrid Current Drive on HT-7 Tokamak
5
作者 刘胜侠 万宝年 +8 位作者 匡光力 高翔 胡立群 秦品健 姚爱玲 龚先祖 石跃江 陈磊 李健刚 《Plasma Science and Technology》 SCIE EI CAS CSCD 2000年第6期523-527,共5页
A perpendicular neutral particle analyzer (NPA) is used on HT-7 tokamak experiment to provide the measurements of neutral particle flux and ion temperature. The measured results were compared with calculated data by ... A perpendicular neutral particle analyzer (NPA) is used on HT-7 tokamak experiment to provide the measurements of neutral particle flux and ion temperature. The measured results were compared with calculated data by Monte-carlo method for ohmic heating. In lower hybrid current drive (LHCD) experiments, the ion heating of LHCD was identified. The chargeexchange neutral particle flux enhanced was observed. The energy spectrum clearly showed a high-energy ions tail. The bulk ion temperature increased by 0.4-0.5 keV after the onset of LHCD. Efficient ion heating of 1 eV. kW-1 was obtained. 展开更多
关键词 LHCD Analysis of Charge-Exchange spectrum during Lower hybrid Current Drive on HT-7 Tokamak HT
下载PDF
The Numerical Calculation and Analysis of the Spectrum of Lower-Hybrid Waves Launched by Grill-Type Antenna on HL-2A
6
作者 曾建尔 陆志鸿 袁勇 《Plasma Science and Technology》 SCIE EI CAS CSCD 2005年第2期2705-2708,共4页
The LHCD antenna that will be used in LH-2A is the original one used in LH-1M, which will be modified. We measured the feature of the antenna, including the reflection of main waveguide, VSWR, the phase shift between ... The LHCD antenna that will be used in LH-2A is the original one used in LH-1M, which will be modified. We measured the feature of the antenna, including the reflection of main waveguide, VSWR, the phase shift between the adjacent sub-waveguides and so on. The paper describes the measured results and spectrum calculation based on the measured parameters. From the works we can assess our antennas correctly, which will be useful in LHCD experiment on HL-2A in the years to come. 展开更多
关键词 lower-hybrid current drive antenna feature spectrum
下载PDF
高性能YVO_(4)基稀土杂化发光材料的构建及其能量传递机制
7
作者 唐鹿 《化工新型材料》 CAS CSCD 北大核心 2024年第5期162-166,共5页
采用溶剂热和离子交换两步实验法,以YVO_(4)为无机基质,2-噻吩甲酰三氟丙酮(TTA)为有机配体,构建了具有核壳结构的YVO_(4)∶Eu^(3+)@YVO_(4)∶Eu^(3+)-TTA稀土杂化发光材料,研究了其高效的发光性能和内部的能量传递机制。结果表明,在62... 采用溶剂热和离子交换两步实验法,以YVO_(4)为无机基质,2-噻吩甲酰三氟丙酮(TTA)为有机配体,构建了具有核壳结构的YVO_(4)∶Eu^(3+)@YVO_(4)∶Eu^(3+)-TTA稀土杂化发光材料,研究了其高效的发光性能和内部的能量传递机制。结果表明,在621nm的监控波长下,YVO_(4)∶Eu^(3+)@YVO_(4)∶Eu^(3+)-TTA稀土杂化发光材料在280~420nm范围内有两个很强的吸收峰(即V-O峰和TTA特征吸收峰)。YVO_(4)基质通过交换作用能量传递,而TTA有机配体通过分子内能量传递,可将吸收的紫外光能量有效地传递给Eu^(3+),从而实现了Eu^(3+)更高效的可见光(红光)发射。 展开更多
关键词 钒酸钇 宽谱激发 稀土杂化发光材料 发光性能 能量传递机制
下载PDF
混合式教学模式在天然药物化学结构波谱解析中的应用
8
作者 关丽 赵惠茹 +1 位作者 杨阳 陈云梅 《化工设计通讯》 CAS 2024年第3期71-73,共3页
随着网络信息技术的快速发展,线上线下混合式教学模式在高校专业课教育中体现出独特的优势。常用的线上线下教学平台包括超星学习通平台、对分易平台、雨课堂等。超星学习通就是这种网络化教学的产物,它极大地改善了传统授课枯燥、单调... 随着网络信息技术的快速发展,线上线下混合式教学模式在高校专业课教育中体现出独特的优势。常用的线上线下教学平台包括超星学习通平台、对分易平台、雨课堂等。超星学习通就是这种网络化教学的产物,它极大地改善了传统授课枯燥、单调以及满堂灌的传统模式。波谱解析是一门理论性很强的学科,主要用于天然药物化学中结构的鉴定,其中包含大量的物理学概念既抽象又深奥,传统的教学模式学生大多提不起兴致,上课效果较差。笔者将超星学习通平台应用于波谱解析这门课程,提高了学生的学习热情。主要介绍了超星学习通平台的功能,并以波谱解析这门课程中的紫外光谱章节为例,探讨基于该平台的混合式教学模式在波谱解析教学全过程中的应用。实践表明,超星学习通平台应用于波谱解析教学,可以调动学生的学习积极性,提高学生的学习兴趣,使师生互动更便捷和迅速,对教学效果的改善具有重要意义。 展开更多
关键词 超星学习通 波谱解析 混合式教学 教学改革
下载PDF
基于DWDM的超100 Gbit/s混合组网分析
9
作者 陈赟昌 梅亮 +1 位作者 贺鸣文 高继韬 《光通信研究》 北大核心 2024年第1期78-84,共7页
【目的】近年来,数据通信量呈爆炸性增长,为了应对高速、高容量数据传输及网络应用场景多样化的需求,超100 Gbit/s密集波分复用(DWDM)混合组网作为一种高效的解决方案逐渐受到关注。文章通过对超100 Gbit/s DWDM混合组网的需求、关键技... 【目的】近年来,数据通信量呈爆炸性增长,为了应对高速、高容量数据传输及网络应用场景多样化的需求,超100 Gbit/s密集波分复用(DWDM)混合组网作为一种高效的解决方案逐渐受到关注。文章通过对超100 Gbit/s DWDM混合组网的需求、关键技术及实际案例进行分析,为构建高容量、高效率的通信网络提供了技术支持和指导。【方法】文章首先阐述了网络发展在容量扩展和支持复杂网络设计方面的需求,其次重点介绍了超100 Gbit/s混合组网的关键技术,包括星座图整形、频谱整形和灵活栅格技术等。其中,为支撑混合组网的业务速率设计,提供了一种用于级联掺铒光纤放大器(EDFA)通信系统的光信噪比(OSNR)计算方法,仅利用信道配置信息、发端信号光功率、EDFA的增益及噪声等相关参数,即可计算出整个链路中各个波长的输出OSNR。最后,结合海外某网络案例,根据实际链路OSNR评估情况,合理进行混合速率网络设计,论证了超100 Gbit/s DWDM混合组网在实际工程中的应用效果。【结果】通过应用超100 Gbit/s DWDM混合组网,根据OSNR评估情况灵活配置传输速率和传输带宽,实现了200、600和800 Gbit/s混合速率网络部署,既满足了核心站点的大容量需求,也兼顾了边缘站点的长途大跨度需求,并在3年期间实现了网络的平滑升级和扩容。【结论】实践证明,超100 Gbit/s DWDM组网能够有效提升网络容量、灵活性及频谱资源利用率,同时也为网络的持续演进提供了空间,是推进大容量光传输网络发展的重要手段。 展开更多
关键词 超100 Gbit/s密集波分复用 混合组网 光信噪比 星座图整形 频谱整形
下载PDF
基于HDSS构建800 MHz的5G和LTE共覆盖研究与实践
10
作者 李文斌 《数字通信世界》 2024年第5期80-83,共4页
800 MHz频段5G是广覆盖很好选择,但是由于800 MHz频率资源短缺,传统的硬重耕方式舍旧换新,不能适应现网需要并且资源投入较大。而频谱动态共享的技术可以在现有4G网络上快速进行5G部署,实现4G和5G双网并存,并动态扩展演进。该文通过对H... 800 MHz频段5G是广覆盖很好选择,但是由于800 MHz频率资源短缺,传统的硬重耕方式舍旧换新,不能适应现网需要并且资源投入较大。而频谱动态共享的技术可以在现有4G网络上快速进行5G部署,实现4G和5G双网并存,并动态扩展演进。该文通过对HDSS的技术的15 MHz HDSS动态频谱共享(15 MHz的NR包含10 MHz的LTE)方案,对共享资源调度、干扰规避、功率配置等关键技术问题进行了分析验证,并对HDSS组网下的多种场景进行了测试,给出了实际配置建议,对实现绿色共享频率资源,4G和5G网络协同、5G的广覆盖等方面具有参考价值。 展开更多
关键词 第五代移动通信新空口技术 频谱共享 混合同频共享
下载PDF
一种UUV集群的隐蔽水声通信低截获技术
11
作者 赵敏捷 胡友峰 +1 位作者 高立 和斌 《舰船科学技术》 北大核心 2024年第10期140-146,共7页
针对当前水下无人航行器(UUV)或水下自主航行器(AUV)集群任务过程中水声通信隐蔽性不足的问题进行研究(简称UUV集群)。首先建立UUV集群的水声隐蔽通信分析模型,明确影响水声通信隐蔽性因素及实现隐蔽通信的技术途径;然后从工程实际的角... 针对当前水下无人航行器(UUV)或水下自主航行器(AUV)集群任务过程中水声通信隐蔽性不足的问题进行研究(简称UUV集群)。首先建立UUV集群的水声隐蔽通信分析模型,明确影响水声通信隐蔽性因素及实现隐蔽通信的技术途径;然后从工程实际的角度给出一种基于时频空及发射功率控制的UUV集群水声隐蔽通信低截获技术实现方法。采用波束定向、宽带混合扩频/编码通信与变步长发射功率控制等综合措施进行水声隐蔽通信系统设计。性能仿真结果表明,上述方法可大大提升UUV集群的水声隐蔽通信低截获性能。 展开更多
关键词 UUV 集群隐蔽通信 截获因子 混合扩频
下载PDF
独塔非对称钢-混混合梁斜拉桥抗震性能研究
12
作者 盖永斌 李欢 +1 位作者 龙绿军 张晋瑞 《长沙理工大学学报(自然科学版)》 CAS 2024年第4期149-159,共11页
【目的】研究独塔非对称钢-混混合梁斜拉桥的抗震性能,并探明非对称结构地震响应的差异。【方法】以长沙香炉洲大桥西汊航道桥为依托,采用MidasCivil软件建立非对称钢-混混合梁斜拉桥全桥有限元模型,分别采用反应谱法和非线性时程分析... 【目的】研究独塔非对称钢-混混合梁斜拉桥的抗震性能,并探明非对称结构地震响应的差异。【方法】以长沙香炉洲大桥西汊航道桥为依托,采用MidasCivil软件建立非对称钢-混混合梁斜拉桥全桥有限元模型,分别采用反应谱法和非线性时程分析法对其进行地震响应分析,并重点研究了结构非对称性对斜拉桥辅助墩、过渡墩及其桩基抗震性能的影响。【结果】独塔非对称钢-混混合梁斜拉桥的动力特性和地震响应规律呈现出明显的非对称性,非对称布置的两过渡墩和两辅助墩在地震作用下的内力响应存在较大差异,结构的非对称性对横向地震更加敏感,在抗震设计时应予以重视;除两过渡墩桩基外,长沙香炉洲大桥按照静力计算设计的结构尺寸及配筋形式均能满足各工况地震作用下的抗震性能目标;塔身、墩身在横向+竖向地震作用下的安全储备均大于纵向+竖向地震的,桩基在横向+竖向地震作用下的安全储备几乎都小于纵向+竖向地震的;受结构非对称性的影响,边跨的27#过渡墩桩基总是先于主跨的31#过渡墩桩基发生破坏;在横向地震作用下,受群桩承台影响横向各排桩基地震轴力有较大差异。【结论】从经济性和抗震合理性角度出发,应对独塔非对称钢-混混合梁斜拉桥进行差异化的抗震设计,研究成果可为非对称斜拉桥及其他非对称桥梁结构的抗震设计提供有益参考。 展开更多
关键词 独塔斜拉桥 非对称结构 钢-混混合梁 抗震性能 反应谱法 非线性时程分析法 弯矩-曲率分析
下载PDF
基于车联网数据的混合动力汽车动力传动系统试验方法研究
13
作者 李升 郑亮 +1 位作者 汤伟雄 李文锋 《汽车工程师》 2024年第2期1-5,共5页
为解决混合动力汽车动力传动系统耐久试验无法全面覆盖用户使用场景的问题,设计了一种基于车联网数据的用户关联正向开发方法。从用户实际典型使用工况出发,结合传动系统疲劳损伤进行规范组合开发,基于用户实际使用习惯和试验场试验载荷... 为解决混合动力汽车动力传动系统耐久试验无法全面覆盖用户使用场景的问题,设计了一种基于车联网数据的用户关联正向开发方法。从用户实际典型使用工况出发,结合传动系统疲劳损伤进行规范组合开发,基于用户实际使用习惯和试验场试验载荷谱,针对将用户使用习惯转化为满足使用寿命要求的整车耐久试验规范开展了研究,确定了车辆试验场耐久试验规范的建立流程,制定了合理有效的混合动力汽车动力传动系统试验规范。 展开更多
关键词 混合动力汽车 动力传动系统 用户关联 载荷谱 疲劳损伤 车联网
下载PDF
Influence of laser on arcs in alternate arcing during laser-twin-arc hybrid welding process 被引量:1
14
作者 顾小燕 李桓 +1 位作者 杨立军 高莹 《China Welding》 EI CAS 2012年第3期55-60,共6页
In this study, multi-information including spectrum, high-speed photograph and electrical signal was adopted to explore the coupling mechanism of alternate burning in laser-twin-arc welding process. Laser provides a c... In this study, multi-information including spectrum, high-speed photograph and electrical signal was adopted to explore the coupling mechanism of alternate burning in laser-twin-arc welding process. Laser provides a conductive, stable plasma channel for arcs. Plasma radiation strengthened especially in the center of the arc after hybrid. High temperature plasma erupting from keyhole provides an upward reacting force which can prevent droplet from transfer. The charged particles consisted in high temperature plasma reduce the voltage that maintains arc ignition or burning. The results show that laser can influence the arc shape, prevent droplet transfer, reduce resistivity and stabilize arcs. 展开更多
关键词 laser-twin-arc hybrid welding coupling mechanism spectrum KEYHOLE alternate burning
下载PDF
Near-field characteristics of highly non-paraxial subwavelength optical fields with hybrid states of polarization 被引量:2
15
作者 陈瑞品 高腾跃 +3 位作者 周健辉 戴朝卿 周国泉 何赛灵 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第10期219-225,共7页
The vectorial structure of an optical field with hybrid states of polarization (SOP) in the near-field is studied by using the angular spectrum method of an electromagnetic beam. Physical images of the longitudinal ... The vectorial structure of an optical field with hybrid states of polarization (SOP) in the near-field is studied by using the angular spectrum method of an electromagnetic beam. Physical images of the longitudinal components of evanescent waves are illustrated and compared with those of the transverse components from the vectorial structure. Our results indicate that the relative weight integrated over the transverse plane of the evanescent wave depends strongly on the number of the polarization topological charges. The shapes of the intensity profiles of the longitudinal components are different from those of the transverse components, and it can be manipulated by changing the initial SoP of the field cross-section. The longitudinal component of evanescent wave dominates the near-field region. In addition, it also leads to three-dimensional shape variations of the optical field and the optical spin angular momentum flux density distributions. 展开更多
关键词 hybrid states of polarization evanescent wave angular spectrum method longitudinal component
下载PDF
Ethoxycarbonylmethyl Viologen Induced Metal Halide-based Hybrids:Structures,Photoluminescence and Photocurrent Response Behavior
16
作者 陈家越 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2018年第11期1756-1764,共9页
Two new ethoxycarbonylmethyl viologen induced metal halide-based hybrids,(Ae V)(BiI)(DMF)(1)and(Ae V)(CoCl)(2)(AeV=N,N?-bis(ethoxycarbonylmethyl)-4,4?-bipyridinium)have been synthesized and structurally determined by ... Two new ethoxycarbonylmethyl viologen induced metal halide-based hybrids,(Ae V)(BiI)(DMF)(1)and(Ae V)(CoCl)(2)(AeV=N,N?-bis(ethoxycarbonylmethyl)-4,4?-bipyridinium)have been synthesized and structurally determined by X-ray diffraction method.Under the direction of a new template AeV,the(BiI)tetramer constructed from four edge-sharing BiIoctahedra(for 1)and(CoCl)mono-nuclear(for 2)were obtained.Furthermore,C–H···O and C–H···X(X=I,Cl)hydrogen bonds contribute to the extension of structures from 0-D to 1-D chains.Their energy band gaps of 2.18 and 2.41 eV indicate their semiconductor properties,and the photoluminescence was detected on 1.Interestingly,2 exhibits good photocurrent response behavior.Electronic structure analysis was executed to correlate the structure/property. 展开更多
关键词 organic-inorganic hybrid optical adsorption spectrum PHOTOLUMINESCENCE photocurrent response
下载PDF
PERFORMANCE ANALYSIS OF HYBRID DS SFH/SSMA SYSTEMS OVER MULTIPATH FADING CHANNELS
17
作者 徐昌庆 林武钦 宋文涛 《Journal of Shanghai Jiaotong university(Science)》 EI 1999年第2期36-40,共5页
Hybrid direct sequence and slow frequency hopping spread spectrum multiple access systems (Hybrid DS/SFH SSMA) operating through nonselective slow Rayleigh fading channels was investigated. Multipath and Multiple acce... Hybrid direct sequence and slow frequency hopping spread spectrum multiple access systems (Hybrid DS/SFH SSMA) operating through nonselective slow Rayleigh fading channels was investigated. Multipath and Multiple access interference was taken into account. Expressions of the average error probability for the system were derived. Analytical and numerical results on the average probability of error were presented for the system examined. Random signature sequences and hopping patterns were employed for the system. The numerical results show the effects of the value of M for M ary frequency shift keying (MFSK) modulation and Reed Solomon (RS) coding on the system’s performance. The comparison between RS coded system and noncode system shows that error correction coding is essential to improve the system’s performance. 展开更多
关键词 hybrid direct sequence/slow FREQUENCY HOPPING spread spectrum multiple access REED SOLOMON code M ary FREQUENCY shift keying multipath fading NONCOHERENT
下载PDF
设备激励下山西河津电厂结构振动测试研究
18
作者 姚泽良 白国良 +2 位作者 党发宁 令狐恬晶 祁亚伦 《振动.测试与诊断》 EI CSCD 北大核心 2023年第6期1198-1204,1249,共8页
利用测振仪对设备激励下大型电厂钢桁架-管柱混合结构体系的扭转振动、竖向振动和水平振动进行了现场试验,采用DASP程序对试验数据进行了时域分析和自谱分析,并结合有限元模拟结果,系统研究了结构的振动响应、横向位移、纵向位移、竖向... 利用测振仪对设备激励下大型电厂钢桁架-管柱混合结构体系的扭转振动、竖向振动和水平振动进行了现场试验,采用DASP程序对试验数据进行了时域分析和自谱分析,并结合有限元模拟结果,系统研究了结构的振动响应、横向位移、纵向位移、竖向位移、变形、转角、振型及频率等关键性能指标。结果表明:结构各特征位置处的测点振动响应曲线不同,同一测点南北与东西向的位移峰值不同步出现,说明结构南北与东西向的振动性能不同;角部的振动位移比中间大,结构出现自身变形和扭转;结构低阶振型接近,存在耦合,说明该结构不适合用底部剪力法计算地震作用;上部结构的相对变形小于其下部结构,顶部A形架的振动出现回缩,说明结构的质量和刚度在A形架处有突变。计算结果与试验结果吻合较好,模态分析结果能为结构动力响应研究提供理论依据。 展开更多
关键词 混合结构 现场试验 振动响应 时域分析 谱分析 自振性能
下载PDF
接触式机械密封混合润滑状态摩擦演化规律研究 被引量:2
19
作者 毕浩程 郝木明 +5 位作者 任宝杰 孙鑫晖 李勇凡 李天照 刘馥瑜 厉晓英 《摩擦学学报》 EI CAS CSCD 北大核心 2023年第11期1241-1253,共13页
接触式机械密封在运转中主要处于混合润滑状态,为探究其混合润滑状态下摩擦机理,结合粗糙面弹塑性模型,求解考虑密封端面粗糙度效应的雷诺方程,探究了转速和介质压力等工况条件对密封混合润滑状态密封摩擦参数的影响,推导了密封声发射... 接触式机械密封在运转中主要处于混合润滑状态,为探究其混合润滑状态下摩擦机理,结合粗糙面弹塑性模型,求解考虑密封端面粗糙度效应的雷诺方程,探究了转速和介质压力等工况条件对密封混合润滑状态密封摩擦参数的影响,推导了密封声发射波能量公式,将密封混合润滑状态分为磨损期和稳定期,应用1.5维谱理论提取密封特征频率,探究混合润滑状态摩擦演化规律.研究结果表明摩擦参数影响密封声发射波能量幅值且密封摩擦形式随混合润滑状态发生变化:在磨损期,微凸体接触特征频率幅值较大,密封端面间摩擦以微凸体接触为主;在稳定期,流体膜黏性剪切摩擦特征频率幅值变大,黏性剪切效应增强,密封端面只存在局部微凸体接触.所得结论对接触式机械密封混合润滑状态摩擦机理的研究具有一定的理论指导意义. 展开更多
关键词 接触式机械密封 混合润滑 摩擦参数 1.5维谱 演化规律
下载PDF
船用主被动混合隔振器的自适应控制研究 被引量:2
20
作者 马召召 周瑞平 +1 位作者 杨庆超 高伟鹏 《船舶力学》 EI CSCD 北大核心 2023年第3期446-455,共10页
为了有效隔离舰船动力机械产生的低频线谱,本文基于电磁橡胶液压一体化主被动混合隔振器,开展混合隔振器的自适应控制研究。首先,将小波包自适应控制算法与Hartley域块算法相结合,提高控制系统的收敛速度;其次,分析块算法中时滞现象对... 为了有效隔离舰船动力机械产生的低频线谱,本文基于电磁橡胶液压一体化主被动混合隔振器,开展混合隔振器的自适应控制研究。首先,将小波包自适应控制算法与Hartley域块算法相结合,提高控制系统的收敛速度;其次,分析块算法中时滞现象对控制系统的影响,并提出时滞在线估计与预测补偿算法,改善控制系统的控制精度,同时对时滞补偿算法的可行性进行仿真分析。实验结果表明,所提出的改进自适应控制算法能够很好地应用于主被动混合隔振器,有效隔离低频线谱。 展开更多
关键词 低频线谱 主被动混合隔振器 Hartley域块算法 时滞 自适应控制
下载PDF
上一页 1 2 14 下一页 到第
使用帮助 返回顶部