The interfacial oxidation behavior of Cr_(4)Mo_(4) V high-speed steel(HSS)joints undergoing hot-compression bonding was investigated by using optical microscopy(OM),scanning electron microscopy(SEM),and transmission e...The interfacial oxidation behavior of Cr_(4)Mo_(4) V high-speed steel(HSS)joints undergoing hot-compression bonding was investigated by using optical microscopy(OM),scanning electron microscopy(SEM),and transmission electron microscopy(TEM).In the heating and holding processes,dispersed rod-like and granularδ-Al_(2)O_(3) oxides were formed at the interface and in the matrix near the interface due to the selective oxidation and internal oxidation of Al,while irregular Si-Al-O compounds and spheroidal SiO_(2) particles were formed at the interface.After the post-holding treatment,SiO_(2) oxides and Si-Al-O compounds were dissolved into the matrix,andδ-Al_(2)O_(3) oxides were transformed into nanoscaleα-Al_(2)O_(3) particles,which did not deteriorate the mechanical properties of the joints.The formation and migration of newly-formed grain boundaries by plastic deformation and post-holding treatment were the main mechanism for interface healing.The tensile test results showed that the strength of the healed joints was comparable to that of the base material,and the in-situ tensile observations proved that the fracture was initiated at the grain boundary of the matrix rather than at the interface.The clarification of interfacial oxides and microstructure is essential for the application of hot-compression bonding of HSSs.展开更多
The rapid advancement of high-speed electronic devices has driven the need for new materials that can meet the demands for higher performance,miniaturization,and energy efficiency.Among these materials,graphene has ga...The rapid advancement of high-speed electronic devices has driven the need for new materials that can meet the demands for higher performance,miniaturization,and energy efficiency.Among these materials,graphene has garnered significant attention due to its exceptional electrical,thermal,and mechanical properties.This paper reviews the research progress on graphene-based composites and their application in high-speed electronics,focusing on the material's unique characteristics and its potential to enhance the performance of electronic devices.The paper examines various graphene-based composite materials,including graphene/polymer,graphene/metal,and graphene/ceramic composites,highlighting their fabrication methods,functionalization strategies,and integration with other materials.Moreover,the paper explores the critical challenges related to scalability,interface compatibility,and integration with existing semiconductor processes.In addition,performance evaluation methodologies and reliability assessments are discussed in the context of electrical,thermal,and mechanical properties.Despite the promising potential of graphene-based composites,challenges such as cost-effective large-scale production,material dispersion,and interface engineering remain.The review concludes by offering insights into future directions for graphene-based materials in high-speed electronic devices,emphasizing the need for further research into scalable manufacturing techniques and functionalization strategies to overcome these challenges.展开更多
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
基于JESD204B接口协议设计和实现了一种新型8B10B编码器。利用极性信息简化编码码表;利用3B4B与5B6B并行编码提升电路工作频率;利用人为加入一位均衡信息,减少逻辑处理层数。仿真结果表明,电路单元面积1 756 mm2、功耗1.13 m W及最大工...基于JESD204B接口协议设计和实现了一种新型8B10B编码器。利用极性信息简化编码码表;利用3B4B与5B6B并行编码提升电路工作频率;利用人为加入一位均衡信息,减少逻辑处理层数。仿真结果表明,电路单元面积1 756 mm2、功耗1.13 m W及最大工作频率342 m Hz,相较于传统方法具有一定的改进且完全符合JESD204B协议规范。可应用于基于JESD204B接口协议的高速串行接口的设计中。展开更多
Due to the fact that ballastless tracks in highspeed railways are not only subjected to repeated train–track dynamic interaction loads,but also suffer from complex environmental loads,the fundamental understanding of...Due to the fact that ballastless tracks in highspeed railways are not only subjected to repeated train–track dynamic interaction loads,but also suffer from complex environmental loads,the fundamental understanding of mechanical performance of ballastless tracks under sophisticated service conditions is an increasingly demanding and challenging issue in high-speed railway networks.This work aims to reveal the effect of train–track interaction and environment loads on the mechanical characteristic variation of ballastless tracks in high-speed railways,particularly focusing on the typical interface damage evolution between track layers.To this end,a finite element model of a double-block ballastless track involving the cohesive zone model for the track interface is first established to analyze the mechanical properties of the track interface under the loading–unloading processes of the negative temperature gradient load(TGL)followed by the same cycle of the positive TGL.Subsequently,the effect of wheel–rail longitudinal interactions on the nonlinear dynamic characteristics of the track interface is investigated by using a vehicle-slab track vertical-longitudinal coupled dynamics model.Finally,the influence of dynamic water pressure induced by vehicle dynamic load on the mechanical characteristics and damage evolution of the track interface is elucidated using a fluid–solid coupling method.Results show that the loading history of the positive and negative TGLs has a great impact on the nonlinear development and distribution of the track interface stress and damage;the interface damage could be induced by the wheel–rail longitudinal vibrations at a high vehicle running speed owing to the dynamic amplification effect caused by short wave irregularities;the vehicle dynamic load could produce considerable water pressure that presents nonlinear spatial–temporal characteristics at the track interface,which would lead to the interface failure under a certain condition due to the coupled dynamic effect of vehicle load and water pressure.展开更多
基金financially supported by the National Key Research and Development Program(No.2018YFA0702900)the National Natural Science Foundation of China(Nos.51774265 and 51701225)+3 种基金the National Science and Technology Major Project of China(Nos.2019ZX06004010 and 2017-VII008-0101)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDC04000000)the LingChuang Research Project of China National Nuclear Corporation Program of CAS Interdisciplinary Innovation TeamYouth Innovation Promotion Association,CAS。
文摘The interfacial oxidation behavior of Cr_(4)Mo_(4) V high-speed steel(HSS)joints undergoing hot-compression bonding was investigated by using optical microscopy(OM),scanning electron microscopy(SEM),and transmission electron microscopy(TEM).In the heating and holding processes,dispersed rod-like and granularδ-Al_(2)O_(3) oxides were formed at the interface and in the matrix near the interface due to the selective oxidation and internal oxidation of Al,while irregular Si-Al-O compounds and spheroidal SiO_(2) particles were formed at the interface.After the post-holding treatment,SiO_(2) oxides and Si-Al-O compounds were dissolved into the matrix,andδ-Al_(2)O_(3) oxides were transformed into nanoscaleα-Al_(2)O_(3) particles,which did not deteriorate the mechanical properties of the joints.The formation and migration of newly-formed grain boundaries by plastic deformation and post-holding treatment were the main mechanism for interface healing.The tensile test results showed that the strength of the healed joints was comparable to that of the base material,and the in-situ tensile observations proved that the fracture was initiated at the grain boundary of the matrix rather than at the interface.The clarification of interfacial oxides and microstructure is essential for the application of hot-compression bonding of HSSs.
文摘The rapid advancement of high-speed electronic devices has driven the need for new materials that can meet the demands for higher performance,miniaturization,and energy efficiency.Among these materials,graphene has garnered significant attention due to its exceptional electrical,thermal,and mechanical properties.This paper reviews the research progress on graphene-based composites and their application in high-speed electronics,focusing on the material's unique characteristics and its potential to enhance the performance of electronic devices.The paper examines various graphene-based composite materials,including graphene/polymer,graphene/metal,and graphene/ceramic composites,highlighting their fabrication methods,functionalization strategies,and integration with other materials.Moreover,the paper explores the critical challenges related to scalability,interface compatibility,and integration with existing semiconductor processes.In addition,performance evaluation methodologies and reliability assessments are discussed in the context of electrical,thermal,and mechanical properties.Despite the promising potential of graphene-based composites,challenges such as cost-effective large-scale production,material dispersion,and interface engineering remain.The review concludes by offering insights into future directions for graphene-based materials in high-speed electronic devices,emphasizing the need for further research into scalable manufacturing techniques and functionalization strategies to overcome these challenges.
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.
文摘基于JESD204B接口协议设计和实现了一种新型8B10B编码器。利用极性信息简化编码码表;利用3B4B与5B6B并行编码提升电路工作频率;利用人为加入一位均衡信息,减少逻辑处理层数。仿真结果表明,电路单元面积1 756 mm2、功耗1.13 m W及最大工作频率342 m Hz,相较于传统方法具有一定的改进且完全符合JESD204B协议规范。可应用于基于JESD204B接口协议的高速串行接口的设计中。
基金the National Natural Science Foundation of China(Nos.51708457,11790283,and 51978587)the Fund from State Key Laboratory of Traction Power(2019TPL-T16)+1 种基金the Young Elite Scientists Sponsorship Program by CAST(2018QNRC001)the 111 Project(Grant No.B16041)。
文摘Due to the fact that ballastless tracks in highspeed railways are not only subjected to repeated train–track dynamic interaction loads,but also suffer from complex environmental loads,the fundamental understanding of mechanical performance of ballastless tracks under sophisticated service conditions is an increasingly demanding and challenging issue in high-speed railway networks.This work aims to reveal the effect of train–track interaction and environment loads on the mechanical characteristic variation of ballastless tracks in high-speed railways,particularly focusing on the typical interface damage evolution between track layers.To this end,a finite element model of a double-block ballastless track involving the cohesive zone model for the track interface is first established to analyze the mechanical properties of the track interface under the loading–unloading processes of the negative temperature gradient load(TGL)followed by the same cycle of the positive TGL.Subsequently,the effect of wheel–rail longitudinal interactions on the nonlinear dynamic characteristics of the track interface is investigated by using a vehicle-slab track vertical-longitudinal coupled dynamics model.Finally,the influence of dynamic water pressure induced by vehicle dynamic load on the mechanical characteristics and damage evolution of the track interface is elucidated using a fluid–solid coupling method.Results show that the loading history of the positive and negative TGLs has a great impact on the nonlinear development and distribution of the track interface stress and damage;the interface damage could be induced by the wheel–rail longitudinal vibrations at a high vehicle running speed owing to the dynamic amplification effect caused by short wave irregularities;the vehicle dynamic load could produce considerable water pressure that presents nonlinear spatial–temporal characteristics at the track interface,which would lead to the interface failure under a certain condition due to the coupled dynamic effect of vehicle load and water pressure.
