With the rapid development of electronic information engineering,high-speed digital circuits have been increasingly widely applied in various fields.In high-speed digital circuits,signal integrity is prone to interfer...With the rapid development of electronic information engineering,high-speed digital circuits have been increasingly widely applied in various fields.In high-speed digital circuits,signal integrity is prone to interference from various external factors,leading to issues such as signal distortion or degradation of system performance.Based on this,this paper conducts research on the optimization strategies for signal integrity of high-speed digital circuits in electronic information engineering.It deeply analyzes the importance of high-speed digital circuits,elaborates on the challenges they face and the specific manifestations of signal integrity issues,and proposes a series of optimization strategies in electronic information engineering.The aim is to improve the signal integrity of highspeed digital circuits and provide theoretical support and practical guidance for the development of related fields.展开更多
This paper studies the interface curing stresses between polymethyl methacrylate (PMMA) and composite by means of digital speckle correlation method (DSCM).A new method by combining DSCM with the marker points is deve...This paper studies the interface curing stresses between polymethyl methacrylate (PMMA) and composite by means of digital speckle correlation method (DSCM).A new method by combining DSCM with the marker points is developed to measure the interface curing stresses,and the measurement principle is introduced.The interface curing stresses between PMMA and composite with different curing bonding conditions are measured and analyzed,this indicates that the residual stress for furnace heating and furnace cooling is the smallest.Finally,the measurement error is discussed by means of finite element method,the influences of glass microsphere between adhesive and PMMA can be ignored.展开更多
Conditional access system (CAS) is a key technical component in digital TV broadcasting through which TV op-erators manage the appropriate rights of different subscribers in order to protect their commercial benefits....Conditional access system (CAS) is a key technical component in digital TV broadcasting through which TV op-erators manage the appropriate rights of different subscribers in order to protect their commercial benefits. The normal digital TV receiver can only receive and decode the pay TV programs scrambled by one specific CAS. In this paper, the authors proposed a smartcard conditional access interface (SCAI) scheme in order to make the digital TV receiver be a common receiving platform independent of any specific CAS employed at the broadcasting head-end. As a result, it only needs to include a common condi-tional access software package (CCAP) without any requirement of hardware modification in the receiver. Comparison between the two mentioned DVB-CI-based schemes showed that the cost of such kind receiver is greatly reduced. The main design points of the proposed scheme and its reference implementation’s architecture are presented in this paper. This scheme is also one of the candidate national standards for Chinese digital TV broadcasting industry.展开更多
Bio-sensor arrays for multi-channel recording have been developed recently and signal processing platforms for those signals have been studied actively.But it’s thereal situation which these technologies are generall...Bio-sensor arrays for multi-channel recording have been developed recently and signal processing platforms for those signals have been studied actively.But it’s thereal situation which these technologies are generally developed and studied respectively.So the interface design between recording array and signal processing platform is also an important issue to make bio-sensor signal processing system.In this paper,we proposed interface which has unique protocols to control sensor array and operate platform.There are two types of protocols in the interface.One is between sensor array and MCU in platform and the other is between MCU and board for wireless communication.Basically,each protocol has two kinds of modes(single,frame)and it can be extended if needed.展开更多
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
Purpose-Conventional high-speed railways(HSR)subgrade design methods remain constrained by platformdependent drafting systems,leading to data interaction hindrances and redundant design processes.This study strives to...Purpose-Conventional high-speed railways(HSR)subgrade design methods remain constrained by platformdependent drafting systems,leading to data interaction hindrances and redundant design processes.This study strives to develop a digital earthwork design methodology that enhances design while reducing collaborative expenses.Design/methodology/approach-A novel digital subgrade design approach,utilizing sophisticated analysis and modeling tools customized for different subgrade elements,is put forward in this study.The methodology incorporates the following essential steps:(1)the advancement of digital analysis and modeling techniques for diverse subgrade components,including surfaces,filling,slopes,retaining structures,and foundation treatments;(2)the formulation of a digital design principle repository incorporating various slope protection combinations;(3)the establishment of a comprehensive digital design framework and process for subgrade cross-sections;and(4)the development and implementation of an open-source digital design system.Findings-The proposed method liberates subgrade design from the constraints of conventional drawing platforms,elevating efficiency,intelligence,and flexibility.The open software architecture and code have achieved over 60%efficiency gains in design workflows during its deployment on three major high-speed rail projects:the Baotou-Yinchuan HSR corridor,Shenyang-Baihe HSR network,and Weifang-Yantai HSR system.Originality/value-This paper introduces an innovative digital design methodology that enables modular and parametric design for railway subgrade sections.The proposed approach provides a digital base for the intelligent design and maintenance of the next-generation high-speed railway.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
In a crumbling tech hub near the marginal coastline,young Angolan developers,despite the challenges of unreliable Internet and dependence on foreign APIs(application programming interfaces),are tapping on donated lapt...In a crumbling tech hub near the marginal coastline,young Angolan developers,despite the challenges of unreliable Internet and dependence on foreign APIs(application programming interfaces),are tapping on donated laptops,debugging health apps that alert rural clinics of disease outbreaks.Their resilience and determination in the face of such obstacles are not just a source of innovation,but also of inspiration and hope.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
To address the flow imbalance rapidly of the asymmetric Electro-Hydrostatic Actuator(EHA),this paper presents a novel architecture of asymmetric EHA with the Digital Distribution(EHA-DD).It also improves the flow nonl...To address the flow imbalance rapidly of the asymmetric Electro-Hydrostatic Actuator(EHA),this paper presents a novel architecture of asymmetric EHA with the Digital Distribution(EHA-DD).It also improves the flow nonlinearity and control accuracy of the pump,especially in the low-speed condition.The digital distribution with two High-Speed on–off Valves(HSVs)not only balances flow instead of the check valves,but also replaces the pump at the low-speed to control output flow by adjusting the PWM signal.The pump and HSVs are the crucial components to control flow output.Firstly,the flow calculation models of the pump and the duty ratio inversed model of the HSV are obtained through experimental tests and the identification method.To get the control input signal for the required flow,the pump speed and PWM duty ratio for the HSVs are inversed to compensate for flow output.Further,a multimode digital flow distribution control method based on pump speed,mainly including the pump-controlled mode for large flow demand and valve-controlled mode for little flow demand,is proposed to control the accurate flow output actively.The step extension experiments based on the flow calculation models are conducted on the EHA-DD prototype under elastic,opposite varying load.The results demonstrate that the EHADD realizes little position error by accurate flow control,and it is also beneficial to improve the service life of the pump.展开更多
With the widespread application of the computer and microelectronic technology in the industry,digitization becomes the inevitable developing trend of the hydraulic technology.Digitization of the hydraulic components ...With the widespread application of the computer and microelectronic technology in the industry,digitization becomes the inevitable developing trend of the hydraulic technology.Digitization of the hydraulic components is critical in the digital hydraulic technology.High-speed on-of valves(HSVs)which convert a train of input pulses into the fast and accurate switching between the on and of states belong to widely used basic digital hydraulic elements.In some ways,the characteristics of the HSVs determine the performance of the digital hydraulic systems.This paper discusses the development of HSVs and their applications.First,the HSVs with innovative structures which is classifed into direct drive valves and pilot operated valves are discussed,with the emphasis on their performance.Then,an overview of HSVs with intelligent materials is presented with considering of the switching frequency and fow capacity.Finally,the applications of the HSVs are reviewed,including digital hydraulic components with the integration of the HSVs and digital hydraulic systems controlled by the HSVs.展开更多
Digital to analog converters(DAC)play an important role as a bridge connecting the analog world and the digital world.With the rapid development of wireless communication,wideband digital radar,and other emerging tech...Digital to analog converters(DAC)play an important role as a bridge connecting the analog world and the digital world.With the rapid development of wireless communication,wideband digital radar,and other emerging technologies,better performing high-speed high-resolution DACs are required.In those applications,signal bandwidth and high-frequency linearity often limited by data converters are the bottleneck of the system.This article reviews the state-of-the-art technologies of high-speed and high-resolution DACs reported in recent years.Comparisons are made between different architectures,circuit implementations and calibration techniques along with the figure of merit(FoM)results.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
Purpose–This paper analyzes the application of digital twin technology in the field of intelligent operation and maintenance of high-speed railway infrastructure from the perspective of top-level design.Design/method...Purpose–This paper analyzes the application of digital twin technology in the field of intelligent operation and maintenance of high-speed railway infrastructure from the perspective of top-level design.Design/methodology/approach–This paper provides a comprehensive overview of the definition,connotations,characteristics and key technologies of digital twin technology.It also conducts a thorough analysis of the current state of digital twin applications,with a particular focus on the overall requirements for intelligent operation and maintenance of high-speed railway infrastructure.Using the Jinan Yellow River Bridge on the Beijing–Shanghai high-speed railway as a case study,the paper details the construction process of the twin system from the perspectives of system architecture,theoretical definition,model construction and platform design.Findings–Digital twin technology can play an important role in the whole life cycle management,fault prediction and condition monitoring in the field of high-speed rail operation and maintenance.Digital twin technology is of great significance to improve the intelligent level of high-speed railway operation and management.Originality/value–This paper systematically summarizes the main components of digital twin railway.The general framework of the digital twin bridge is given,and its application in the field of intelligent operation and maintenance is prospected.展开更多
Zinc ion batteries are considered as potential energy storage devices due to their advantages of low-cost,high-safety,and high theoretical capacity.However,dendrite growth and chemical corrosion occurring on Zn anode ...Zinc ion batteries are considered as potential energy storage devices due to their advantages of low-cost,high-safety,and high theoretical capacity.However,dendrite growth and chemical corrosion occurring on Zn anode limit their commercialization.These problems can be tackled through the optimization of the electrolyte.However,the screening of electrolyte additives using normal electrochemical methods is time-consuming and labor-intensive.Herein,a fast and simple method based on the digital holography is developed.It can realize the in situ monitoring of electrode/electrolyte interface and provide direct information concerning ion concentration evolution of the diffusion layer.It is effective and time-saving in estimating the homogeneity of the deposition layer and predicting the tendency of dendrite growth,thus able to value the applicability of electrolyte additives.The feasibility of this method is further validated by the forecast and evaluation of thioacetamide additive.Based on systematic characterization,it is proved that the introduction of thioacetamide can not only regulate the interficial ion flux to induce dendrite-free Zn deposition,but also construct adsorption molecule layers to inhibit side reactions of Zn anode.Being easy to operate,capable of in situ observation,and able to endure harsh conditions,digital holography method will be a promising approach for the interfacial investigation of other battery systems.展开更多
Based on the characteristics of field-programmable gate array(FPGA) such as multi-task,high-speed,parallelity,etc,a filtering algorithm is presented to filter the output signal of laser gyr o with high-speed and high ...Based on the characteristics of field-programmable gate array(FPGA) such as multi-task,high-speed,parallelity,etc,a filtering algorithm is presented to filter the output signal of laser gyr o with high-speed and high accuracy.The filter is composed of basic logic cell s,multipliers an d memory inside FPGA.By using an multiplication decomposition method and design ing reliable time-sequence,the filter is realized,which is easy to be transpl anted and of low cost.Furthermore,all the signal demodulation algorithms of t he laser gyr oscope can be integrated in only one FPGA,which reduces the cost and complexity of the system.展开更多
This paper investigates the reproduction of Chinese painting in the digital age. In particular, how does a website asan interface influence viewers’ response to a Chinese handscroll? The paper begins with a critical ...This paper investigates the reproduction of Chinese painting in the digital age. In particular, how does a website asan interface influence viewers’ response to a Chinese handscroll? The paper begins with a critical description of aweb interface of Freer Gallery of Art and Arthur M. Sackler Gallery, followed by an analysis of the originalpainting. Fishermen on an Autumn River, that the interface digitizes and displays. The last section points out theinfluence of digitization on the relationship between viewers and digital heritage.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
文摘With the rapid development of electronic information engineering,high-speed digital circuits have been increasingly widely applied in various fields.In high-speed digital circuits,signal integrity is prone to interference from various external factors,leading to issues such as signal distortion or degradation of system performance.Based on this,this paper conducts research on the optimization strategies for signal integrity of high-speed digital circuits in electronic information engineering.It deeply analyzes the importance of high-speed digital circuits,elaborates on the challenges they face and the specific manifestations of signal integrity issues,and proposes a series of optimization strategies in electronic information engineering.The aim is to improve the signal integrity of highspeed digital circuits and provide theoretical support and practical guidance for the development of related fields.
基金supported by the National Basic Research Program (973 Program) of China (2011CB606105)
文摘This paper studies the interface curing stresses between polymethyl methacrylate (PMMA) and composite by means of digital speckle correlation method (DSCM).A new method by combining DSCM with the marker points is developed to measure the interface curing stresses,and the measurement principle is introduced.The interface curing stresses between PMMA and composite with different curing bonding conditions are measured and analyzed,this indicates that the residual stress for furnace heating and furnace cooling is the smallest.Finally,the measurement error is discussed by means of finite element method,the influences of glass microsphere between adhesive and PMMA can be ignored.
基金Project (No. 200442) supported by the Electronics DevelopmentFoundation for the Key Industrialization Project of the Ministry of0Information Industry, China
文摘Conditional access system (CAS) is a key technical component in digital TV broadcasting through which TV op-erators manage the appropriate rights of different subscribers in order to protect their commercial benefits. The normal digital TV receiver can only receive and decode the pay TV programs scrambled by one specific CAS. In this paper, the authors proposed a smartcard conditional access interface (SCAI) scheme in order to make the digital TV receiver be a common receiving platform independent of any specific CAS employed at the broadcasting head-end. As a result, it only needs to include a common condi-tional access software package (CCAP) without any requirement of hardware modification in the receiver. Comparison between the two mentioned DVB-CI-based schemes showed that the cost of such kind receiver is greatly reduced. The main design points of the proposed scheme and its reference implementation’s architecture are presented in this paper. This scheme is also one of the candidate national standards for Chinese digital TV broadcasting industry.
文摘Bio-sensor arrays for multi-channel recording have been developed recently and signal processing platforms for those signals have been studied actively.But it’s thereal situation which these technologies are generally developed and studied respectively.So the interface design between recording array and signal processing platform is also an important issue to make bio-sensor signal processing system.In this paper,we proposed interface which has unique protocols to control sensor array and operate platform.There are two types of protocols in the interface.One is between sensor array and MCU in platform and the other is between MCU and board for wireless communication.Basically,each protocol has two kinds of modes(single,frame)and it can be extended if needed.
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.
基金supported by the major project of China State Railway Group Co.,Ltd.(No.Q2023G020)the internal project of China Railway Design Cooperation(No.2023A0248002).
文摘Purpose-Conventional high-speed railways(HSR)subgrade design methods remain constrained by platformdependent drafting systems,leading to data interaction hindrances and redundant design processes.This study strives to develop a digital earthwork design methodology that enhances design while reducing collaborative expenses.Design/methodology/approach-A novel digital subgrade design approach,utilizing sophisticated analysis and modeling tools customized for different subgrade elements,is put forward in this study.The methodology incorporates the following essential steps:(1)the advancement of digital analysis and modeling techniques for diverse subgrade components,including surfaces,filling,slopes,retaining structures,and foundation treatments;(2)the formulation of a digital design principle repository incorporating various slope protection combinations;(3)the establishment of a comprehensive digital design framework and process for subgrade cross-sections;and(4)the development and implementation of an open-source digital design system.Findings-The proposed method liberates subgrade design from the constraints of conventional drawing platforms,elevating efficiency,intelligence,and flexibility.The open software architecture and code have achieved over 60%efficiency gains in design workflows during its deployment on three major high-speed rail projects:the Baotou-Yinchuan HSR corridor,Shenyang-Baihe HSR network,and Weifang-Yantai HSR system.Originality/value-This paper introduces an innovative digital design methodology that enables modular and parametric design for railway subgrade sections.The proposed approach provides a digital base for the intelligent design and maintenance of the next-generation high-speed railway.
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.
文摘In a crumbling tech hub near the marginal coastline,young Angolan developers,despite the challenges of unreliable Internet and dependence on foreign APIs(application programming interfaces),are tapping on donated laptops,debugging health apps that alert rural clinics of disease outbreaks.Their resilience and determination in the face of such obstacles are not just a source of innovation,but also of inspiration and hope.
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co-supported by the National Natural Science Foundation of China(Nos.51890811 and 51975507)the Innovation Funding for Postgraduates in Hebei Province(No.CXZZSS2019042)。
文摘To address the flow imbalance rapidly of the asymmetric Electro-Hydrostatic Actuator(EHA),this paper presents a novel architecture of asymmetric EHA with the Digital Distribution(EHA-DD).It also improves the flow nonlinearity and control accuracy of the pump,especially in the low-speed condition.The digital distribution with two High-Speed on–off Valves(HSVs)not only balances flow instead of the check valves,but also replaces the pump at the low-speed to control output flow by adjusting the PWM signal.The pump and HSVs are the crucial components to control flow output.Firstly,the flow calculation models of the pump and the duty ratio inversed model of the HSV are obtained through experimental tests and the identification method.To get the control input signal for the required flow,the pump speed and PWM duty ratio for the HSVs are inversed to compensate for flow output.Further,a multimode digital flow distribution control method based on pump speed,mainly including the pump-controlled mode for large flow demand and valve-controlled mode for little flow demand,is proposed to control the accurate flow output actively.The step extension experiments based on the flow calculation models are conducted on the EHA-DD prototype under elastic,opposite varying load.The results demonstrate that the EHADD realizes little position error by accurate flow control,and it is also beneficial to improve the service life of the pump.
基金Supported by Key Technologies Research and Development Program of China(Grant No.2019YFB2004502)National Natural Science Foundation of China(Grant Nos.51805350,51775362)Postdoctoral Science Foundation of China(Grant No.2019M651073).
文摘With the widespread application of the computer and microelectronic technology in the industry,digitization becomes the inevitable developing trend of the hydraulic technology.Digitization of the hydraulic components is critical in the digital hydraulic technology.High-speed on-of valves(HSVs)which convert a train of input pulses into the fast and accurate switching between the on and of states belong to widely used basic digital hydraulic elements.In some ways,the characteristics of the HSVs determine the performance of the digital hydraulic systems.This paper discusses the development of HSVs and their applications.First,the HSVs with innovative structures which is classifed into direct drive valves and pilot operated valves are discussed,with the emphasis on their performance.Then,an overview of HSVs with intelligent materials is presented with considering of the switching frequency and fow capacity.Finally,the applications of the HSVs are reviewed,including digital hydraulic components with the integration of the HSVs and digital hydraulic systems controlled by the HSVs.
文摘Digital to analog converters(DAC)play an important role as a bridge connecting the analog world and the digital world.With the rapid development of wireless communication,wideband digital radar,and other emerging technologies,better performing high-speed high-resolution DACs are required.In those applications,signal bandwidth and high-frequency linearity often limited by data converters are the bottleneck of the system.This article reviews the state-of-the-art technologies of high-speed and high-resolution DACs reported in recent years.Comparisons are made between different architectures,circuit implementations and calibration techniques along with the figure of merit(FoM)results.
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.
基金funded by the China State Railway Group Co.,Ltd.Science and technology research and development program project(K2023G085).
文摘Purpose–This paper analyzes the application of digital twin technology in the field of intelligent operation and maintenance of high-speed railway infrastructure from the perspective of top-level design.Design/methodology/approach–This paper provides a comprehensive overview of the definition,connotations,characteristics and key technologies of digital twin technology.It also conducts a thorough analysis of the current state of digital twin applications,with a particular focus on the overall requirements for intelligent operation and maintenance of high-speed railway infrastructure.Using the Jinan Yellow River Bridge on the Beijing–Shanghai high-speed railway as a case study,the paper details the construction process of the twin system from the perspectives of system architecture,theoretical definition,model construction and platform design.Findings–Digital twin technology can play an important role in the whole life cycle management,fault prediction and condition monitoring in the field of high-speed rail operation and maintenance.Digital twin technology is of great significance to improve the intelligent level of high-speed railway operation and management.Originality/value–This paper systematically summarizes the main components of digital twin railway.The general framework of the digital twin bridge is given,and its application in the field of intelligent operation and maintenance is prospected.
基金supported by the National Natural Science Foundation of China(No.22075115)Natural Science Foundation of Jiangsu Province(No.BK20211352)+2 种基金Joint Funds of the National Natural Science Foundation of China(No.U2141201)Natural Science Foundation(No.22KJA430005)of Jiangsu Education Committee of ChinaPostgraduate Research and Practice Innovation Program of Jiangsu Normal University(No.2021XKT0296).
文摘Zinc ion batteries are considered as potential energy storage devices due to their advantages of low-cost,high-safety,and high theoretical capacity.However,dendrite growth and chemical corrosion occurring on Zn anode limit their commercialization.These problems can be tackled through the optimization of the electrolyte.However,the screening of electrolyte additives using normal electrochemical methods is time-consuming and labor-intensive.Herein,a fast and simple method based on the digital holography is developed.It can realize the in situ monitoring of electrode/electrolyte interface and provide direct information concerning ion concentration evolution of the diffusion layer.It is effective and time-saving in estimating the homogeneity of the deposition layer and predicting the tendency of dendrite growth,thus able to value the applicability of electrolyte additives.The feasibility of this method is further validated by the forecast and evaluation of thioacetamide additive.Based on systematic characterization,it is proved that the introduction of thioacetamide can not only regulate the interficial ion flux to induce dendrite-free Zn deposition,but also construct adsorption molecule layers to inhibit side reactions of Zn anode.Being easy to operate,capable of in situ observation,and able to endure harsh conditions,digital holography method will be a promising approach for the interfacial investigation of other battery systems.
文摘Based on the characteristics of field-programmable gate array(FPGA) such as multi-task,high-speed,parallelity,etc,a filtering algorithm is presented to filter the output signal of laser gyr o with high-speed and high accuracy.The filter is composed of basic logic cell s,multipliers an d memory inside FPGA.By using an multiplication decomposition method and design ing reliable time-sequence,the filter is realized,which is easy to be transpl anted and of low cost.Furthermore,all the signal demodulation algorithms of t he laser gyr oscope can be integrated in only one FPGA,which reduces the cost and complexity of the system.
文摘This paper investigates the reproduction of Chinese painting in the digital age. In particular, how does a website asan interface influence viewers’ response to a Chinese handscroll? The paper begins with a critical description of aweb interface of Freer Gallery of Art and Arthur M. Sackler Gallery, followed by an analysis of the originalpainting. Fishermen on an Autumn River, that the interface digitizes and displays. The last section points out theinfluence of digitization on the relationship between viewers and digital heritage.
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.
