The damage of the self-compacting concrete in CRTSⅢslab ballastless track on bridge will lead to a partial void of the track slab,which will affect the comfort and safety of the train and the durability of the track ...The damage of the self-compacting concrete in CRTSⅢslab ballastless track on bridge will lead to a partial void of the track slab,which will affect the comfort and safety of the train and the durability of the track slab and bridge structure.In order to study the impact of the interface crack on the dynamic response of CRTSⅢballastless track system on bridge,based on the principle of multi-body dynamics theory and ANSYS+SIMPACK co-simulation,the spatial model of vehicle-track-bridge integration considering the longitudinal stiffness of supports,the track structure and interlayer contact characteristics were established.The dynamic characteristics of the system under different conditions of the width,length and position of the interface crack were analysed,and the limited values of the length and width of the cracks at the track slab edge were proposed.The results show that when the self-compacting concrete does not completely void along the transverse direction of the track slab,the crack has little effect on the dynamic characteristics of the vehicle-track-bridge system.However,when the self-compacting concrete is completely hollowed out along the transverse direction of the track slab,the dynamic amplitudes of the system increase.When the crack length is 1.6 m,the wheel load reduction rate reaches 0.769,which exceeds the limit value and threatens the safety of train operation.The vertical acceleration of the track slab increases by 250.1%,which affects the service life of the track system under the train speed of 200 km/h.展开更多
The Richtmyer-Meshkov instability ofa ‘V＇ shaped air/helium gaseous interface subjected to a weak shock wave is experimentally studied. A soap film technique is adopted to create a ‘V＇ shaped interface with accura...The Richtmyer-Meshkov instability ofa ‘V＇ shaped air/helium gaseous interface subjected to a weak shock wave is experimentally studied. A soap film technique is adopted to create a ‘V＇ shaped interface with accurate initial conditions. Five kinds of ‘V＇ shaped interfaces with different vertex angles are formed to highlight the effects of initial conditions on the flow characteristics. The results show that a spike is generated after the shock impact, and grows constantly with time. As the vertex angle increases, vortices generated on the interface become less noticeable, and the spike develops less pronouncedly. The linear growth rate of interface width after compression phase is estimated by a linear model and a revised linear model, and the latter is proven to be more effective for the interface with high initial amplitudes. The linear growth rate of interface width is, for the first time in a heavy/light interface configuration, found to be a non-monotonous function of the initial perturbation amplitude-wavelength ratio.展开更多
The paper presents the design and implementation of LVDS （low-voltage differential signaling） receiver circuit, fully compatible with LVDS standard. The proposed circuit is composed of the telescopic amplifier and t...The paper presents the design and implementation of LVDS （low-voltage differential signaling） receiver circuit, fully compatible with LVDS standard. The proposed circuit is composed of the telescopic amplifier and the comparator with internal hysteresis. The receiver supports 3.5 Gbps data rate with 7.4 mA current at 1.8 V supply according to post-layout circuit simulations. The circuit has the power consumption of 13.1 MW. Comparing with the conventional circuit, the circuit is achieved to reduce the power consumption by 19.1% and the data rate by 14.3 %. The validity and effectiveness of the proposed circuit are verified through the circuit simulation with Samsung 0.18 μm CMOS （complementary metal-oxide-semiconductor） standard technology under the 1.8 V supply voltage.展开更多
在广播电视行业,4K、8K超高清技术的快速发展,对于信号传输产生了更高的要求,需要更高的带宽和更低的延迟。在这种情况下,传统的串行数字接口(Serial Digital Interface,SDI)技术已经不能满足,需要向网际互连协议(Internet Protocol,IP...在广播电视行业,4K、8K超高清技术的快速发展,对于信号传输产生了更高的要求,需要更高的带宽和更低的延迟。在这种情况下,传统的串行数字接口(Serial Digital Interface,SDI)技术已经不能满足,需要向网际互连协议(Internet Protocol,IP)化转化。针对SDI技术的局限性以及IP技术的优势进行阐述,发现IP化不仅可以提升传输效率、降低传输成本,还可以促进广播电视行业的创新和发展。展开更多
随着基于电影和电视工程师协会(The Society of Motion Picture and Television Engineers,SMPTE)ST 2110标准的网际互连协议(Internet Protocol,IP)化电视系统越来越多,传统串行数字接口(Serial Digital Interface,SDI)架构电视系统测...随着基于电影和电视工程师协会(The Society of Motion Picture and Television Engineers,SMPTE)ST 2110标准的网际互连协议(Internet Protocol,IP)化电视系统越来越多,传统串行数字接口(Serial Digital Interface,SDI)架构电视系统测量方法在IP化电视系统中已不再适用。对此,详细介绍IP测量与SDI测量的区别与联系,以及IP架构电视系统测量的内容、方法及相关指标,以期在IP化电视系统出现问题时,能够通过相关测量,快速定位、解决系统故障。展开更多
近年来,广播电视技术转型向网际互连协议(Internet Protocol,IP)化发展的进程逐渐加快,基于IP架构的电视技术系统必将取代传统串行数字接口(Serial Digital Interface,SDI)架构,成为未来电视技术的发展方向。对以互联网协议网关(Interne...近年来,广播电视技术转型向网际互连协议(Internet Protocol,IP)化发展的进程逐渐加快,基于IP架构的电视技术系统必将取代传统串行数字接口(Serial Digital Interface,SDI)架构,成为未来电视技术的发展方向。对以互联网协议网关(Internet Protocol Gateway,IPG)作为关键设备搭建“SDI+IP”混合架构系统的设计方案进行深入分析,阐述电视技术系统从SDI向IP技术转型过程中尽可能实现平稳过渡的思路。展开更多
基金Acknowledgements： This work was partially supported by Natural Science Foundation of Liaoning Province, China （No. 20042042）, Specialized Research Fund for the Doctoral Program of Higher Education of China （No. 20030145017）.
基金Project(2017YFB1201204)supported by National Key R&D Program of China。
文摘The damage of the self-compacting concrete in CRTSⅢslab ballastless track on bridge will lead to a partial void of the track slab,which will affect the comfort and safety of the train and the durability of the track slab and bridge structure.In order to study the impact of the interface crack on the dynamic response of CRTSⅢballastless track system on bridge,based on the principle of multi-body dynamics theory and ANSYS+SIMPACK co-simulation,the spatial model of vehicle-track-bridge integration considering the longitudinal stiffness of supports,the track structure and interlayer contact characteristics were established.The dynamic characteristics of the system under different conditions of the width,length and position of the interface crack were analysed,and the limited values of the length and width of the cracks at the track slab edge were proposed.The results show that when the self-compacting concrete does not completely void along the transverse direction of the track slab,the crack has little effect on the dynamic characteristics of the vehicle-track-bridge system.However,when the self-compacting concrete is completely hollowed out along the transverse direction of the track slab,the dynamic amplitudes of the system increase.When the crack length is 1.6 m,the wheel load reduction rate reaches 0.769,which exceeds the limit value and threatens the safety of train operation.The vertical acceleration of the track slab increases by 250.1%,which affects the service life of the track system under the train speed of 200 km/h.
基金supported by the National Natural Science Foundation of China(U1530103,11302219,and 11272308)
文摘The Richtmyer-Meshkov instability ofa ‘V＇ shaped air/helium gaseous interface subjected to a weak shock wave is experimentally studied. A soap film technique is adopted to create a ‘V＇ shaped interface with accurate initial conditions. Five kinds of ‘V＇ shaped interfaces with different vertex angles are formed to highlight the effects of initial conditions on the flow characteristics. The results show that a spike is generated after the shock impact, and grows constantly with time. As the vertex angle increases, vortices generated on the interface become less noticeable, and the spike develops less pronouncedly. The linear growth rate of interface width after compression phase is estimated by a linear model and a revised linear model, and the latter is proven to be more effective for the interface with high initial amplitudes. The linear growth rate of interface width is, for the first time in a heavy/light interface configuration, found to be a non-monotonous function of the initial perturbation amplitude-wavelength ratio.
文摘The paper presents the design and implementation of LVDS （low-voltage differential signaling） receiver circuit, fully compatible with LVDS standard. The proposed circuit is composed of the telescopic amplifier and the comparator with internal hysteresis. The receiver supports 3.5 Gbps data rate with 7.4 mA current at 1.8 V supply according to post-layout circuit simulations. The circuit has the power consumption of 13.1 MW. Comparing with the conventional circuit, the circuit is achieved to reduce the power consumption by 19.1% and the data rate by 14.3 %. The validity and effectiveness of the proposed circuit are verified through the circuit simulation with Samsung 0.18 μm CMOS （complementary metal-oxide-semiconductor） standard technology under the 1.8 V supply voltage.
文摘在广播电视行业,4K、8K超高清技术的快速发展,对于信号传输产生了更高的要求,需要更高的带宽和更低的延迟。在这种情况下,传统的串行数字接口(Serial Digital Interface,SDI)技术已经不能满足,需要向网际互连协议(Internet Protocol,IP)化转化。针对SDI技术的局限性以及IP技术的优势进行阐述,发现IP化不仅可以提升传输效率、降低传输成本,还可以促进广播电视行业的创新和发展。
文摘随着基于电影和电视工程师协会(The Society of Motion Picture and Television Engineers,SMPTE)ST 2110标准的网际互连协议(Internet Protocol,IP)化电视系统越来越多,传统串行数字接口(Serial Digital Interface,SDI)架构电视系统测量方法在IP化电视系统中已不再适用。对此,详细介绍IP测量与SDI测量的区别与联系,以及IP架构电视系统测量的内容、方法及相关指标,以期在IP化电视系统出现问题时,能够通过相关测量,快速定位、解决系统故障。
