Shear failure in panel zones and plastic hinges in steel beams are the two major failure modes of connections between concrete-filled steel tubular(CFST) columns and steel beams. To investigate the behavior of this ty...Shear failure in panel zones and plastic hinges in steel beams are the two major failure modes of connections between concrete-filled steel tubular(CFST) columns and steel beams. To investigate the behavior of this type of connection in both modes,two through-diaphragm connections were tested under cyclic and monotonic loadings and the load-carrying capacity,ductility,and strength of degradation of connections were discussed. Using ABAQUS software,we developed nonlinear finite-element models(FEMs) to simulate the load-carrying capacity and failure modes of the connections under monotonic loading. The finite-element(FE) analysis and test results showed reasonable agreement for the through-diaphragm connections,which confirms the accuracy of FEMs in predicting the load-carrying capacity and failure modes of connections. Based on the validated FEM,a parametric study was then conducted to investigate the infl uence of the thicknesses of the tube and diaphragm on the load-carrying capacity and failure modes of these connections. The results indicate that the strength,stiff ness,and load-carrying capacity are infl uenced less by the thickness of the diaphragm,and more by the thickness of the steel tube. According to the FE analysis results,it can be found that the critical condition between the two failure modes is determined by the shear resistance and bending resistance.展开更多
The mode switching between spatial multiplexing （SM） and space-time block code （STBC） diversity is investigated for the multiple-input multiple-output （MIMO） automatic repeat request （ARQ） system. Five importa...The mode switching between spatial multiplexing （SM） and space-time block code （STBC） diversity is investigated for the multiple-input multiple-output （MIMO） automatic repeat request （ARQ） system. Five important practical factors are considered in the proposed switching scheme： transmit correlation, ARQ technique, packet loss probability （PLP） constraint, discrete rate transmission （DRT） and channel coding. Under the spatially correlated channel, the distributions of the post signal-to-interference-plus- noise ratio （SiNR） for the SM mode and the STBC mode are obtained by using Gamma approximations. Then this paper derives the closed-form expressions of the PLP and the throughput for different modes when the ARQ technique is employed, based on which the mode switching algorithm is proposed to improve the spectral efficency. In the simulation, the correction of the expressions is first verified. Then, the significant gain observed by the proposed algorithm is presented. Since the switching point is the key parameter to implement the mode switching, this paper also shows how the switching point is affected by the practical factors considered.展开更多
In ultra-wideband through-wall-imaging applications, wall clutters are always much stronger than the target reflections, and they tend to persist over a long period of time. As a result, targets are obscured and not v...In ultra-wideband through-wall-imaging applications, wall clutters are always much stronger than the target reflections, and they tend to persist over a long period of time. As a result, targets are obscured and not visible in the image. In this work, an antenna planes-based wall clutter mitigation method was proposed. By using two imaging procedures in different scanning planes, this method can mitigate the wall clutter in both SAR and MIMO modes. The proposed method was tested using EM numerical data via the FDTD method. The processing results show that the imaging quality is improved significantly.展开更多
大规模电化学储能系统(battery energy storage system,BESS)送出线路发生故障时,受其低电压穿越控制(low voltage ride-through,LVRT)策略的影响,其正序故障分量阻抗特征与传统电源存在较大差异。本文基于BESS相关的技术规定,根据BESS...大规模电化学储能系统(battery energy storage system,BESS)送出线路发生故障时,受其低电压穿越控制(low voltage ride-through,LVRT)策略的影响,其正序故障分量阻抗特征与传统电源存在较大差异。本文基于BESS相关的技术规定,根据BESS故障前后的充放电模式将其工作模式转换方式分为3种,进一步计及BESS的LVRT控制策略,推导出不同工作模式转化方式下其正序故障分量阻抗角的表达式,从而分析了不同影响因素对BESS正序故障分量阻抗角的影响,并据此研究了正序故障分量方向元件在BESS接入场景下的适应性。最后利用Matlab/Simulink仿真平台验证了理论分析的正确性。展开更多
基金supported by the National Natural Science Foundation of China (Nos. 51268054 and 51468061)the Natural Science Foundation of Tianjin, China (No. 13JCQNJC07300)
文摘Shear failure in panel zones and plastic hinges in steel beams are the two major failure modes of connections between concrete-filled steel tubular(CFST) columns and steel beams. To investigate the behavior of this type of connection in both modes,two through-diaphragm connections were tested under cyclic and monotonic loadings and the load-carrying capacity,ductility,and strength of degradation of connections were discussed. Using ABAQUS software,we developed nonlinear finite-element models(FEMs) to simulate the load-carrying capacity and failure modes of the connections under monotonic loading. The finite-element(FE) analysis and test results showed reasonable agreement for the through-diaphragm connections,which confirms the accuracy of FEMs in predicting the load-carrying capacity and failure modes of connections. Based on the validated FEM,a parametric study was then conducted to investigate the infl uence of the thicknesses of the tube and diaphragm on the load-carrying capacity and failure modes of these connections. The results indicate that the strength,stiff ness,and load-carrying capacity are infl uenced less by the thickness of the diaphragm,and more by the thickness of the steel tube. According to the FE analysis results,it can be found that the critical condition between the two failure modes is determined by the shear resistance and bending resistance.
基金supported by the Chinese Important National Science and Technology Specific Project(2010ZX03002-003-01)
文摘The mode switching between spatial multiplexing （SM） and space-time block code （STBC） diversity is investigated for the multiple-input multiple-output （MIMO） automatic repeat request （ARQ） system. Five important practical factors are considered in the proposed switching scheme： transmit correlation, ARQ technique, packet loss probability （PLP） constraint, discrete rate transmission （DRT） and channel coding. Under the spatially correlated channel, the distributions of the post signal-to-interference-plus- noise ratio （SiNR） for the SM mode and the STBC mode are obtained by using Gamma approximations. Then this paper derives the closed-form expressions of the PLP and the throughput for different modes when the ARQ technique is employed, based on which the mode switching algorithm is proposed to improve the spectral efficency. In the simulation, the correction of the expressions is first verified. Then, the significant gain observed by the proposed algorithm is presented. Since the switching point is the key parameter to implement the mode switching, this paper also shows how the switching point is affected by the practical factors considered.
基金Projects(61372161,61271441)supported by the National Natural Science Foundation of China
文摘In ultra-wideband through-wall-imaging applications, wall clutters are always much stronger than the target reflections, and they tend to persist over a long period of time. As a result, targets are obscured and not visible in the image. In this work, an antenna planes-based wall clutter mitigation method was proposed. By using two imaging procedures in different scanning planes, this method can mitigate the wall clutter in both SAR and MIMO modes. The proposed method was tested using EM numerical data via the FDTD method. The processing results show that the imaging quality is improved significantly.
文摘大规模电化学储能系统(battery energy storage system,BESS)送出线路发生故障时,受其低电压穿越控制(low voltage ride-through,LVRT)策略的影响,其正序故障分量阻抗特征与传统电源存在较大差异。本文基于BESS相关的技术规定,根据BESS故障前后的充放电模式将其工作模式转换方式分为3种,进一步计及BESS的LVRT控制策略,推导出不同工作模式转化方式下其正序故障分量阻抗角的表达式,从而分析了不同影响因素对BESS正序故障分量阻抗角的影响,并据此研究了正序故障分量方向元件在BESS接入场景下的适应性。最后利用Matlab/Simulink仿真平台验证了理论分析的正确性。
文摘目的:探讨奥瑞姆(The Orem Self-Care Model,Orem)自护模式在非霍奇金淋巴瘤(Non-Hodgkin lymphoma,NHL)经外周静脉置入中心静脉导管(Peripherally Inserted Central Catheter,PICC)置管化疗患者中的应用效果。方法:选取2022年4月至2024年4月本院收治的86例NHL患者作为研究对象,采用随机数字表法分为对照组和观察组,各43例。对照组采取常规护理,观察组采用Orem自护模式,两组均持续护理至患者出院。比较两组患者对疾病相关知识认知、自我护理能力、并发症发生率、生活质量以及护理满意度。结果:护理后,观察组患者的疾病相关知识认知各项评分、自我护理能力测定量表(Exercise of Self-Care Agency Scale,ESCA)各项评分、生存质量简表(Quality of Life-BREF,QOL-BREF)各项评分、以及护理满意度各项评分均明显高于对照组(P<0.05),观察组并发症总发生率明显低于对照组(P<0.05)。结论:Orem自护模式可提升NHL经PICC置管化疗患者对疾病相关知识的掌握,加强患者的防护意思,提高患者的自护能力,有助于减少和预防并发症的发生,促进患者生活质量改善,使患者对护理服务的更加满意。
