In this article, we discuss several properties of the basic contact process on hexagonal lattice H, showing that it behaves quite similar to the process on d-dimensional lattice Zd in many aspects. Firstly, we constru...In this article, we discuss several properties of the basic contact process on hexagonal lattice H, showing that it behaves quite similar to the process on d-dimensional lattice Zd in many aspects. Firstly, we construct a coupling between the contact process on hexagonal lattice and the oriented percolation, and prove an equivalent finite space-time condition for the survival of the process. Secondly, we show the complete convergence theorem and the polynomial growth hold for the contact process on hexagonal lattice. Finally, we prove exponential bounds in the supercritical case and exponential decay rates in the subcritical case of the process.展开更多
The author considers the contact process on a branching plane Td×Z, which is the product of a regular tree Td and the line Z. It is shown that above the second critical point, the complete convergence theory holds.
This paper shows that for a supercritical contact process in one dimension, if the initial distribution satisfies reasonable hypothesis, then the first hitting time of certain set with anomalous small density is asymp...This paper shows that for a supercritical contact process in one dimension, if the initial distribution satisfies reasonable hypothesis, then the first hitting time of certain set with anomalous small density is asymptotically exponentially distributed. We also show the similar result for the contact process on the finite set [0, N].展开更多
This paper analyzes the dynamics of a two-strain symbiotic contact process on graphs using a discrete-time nonlinear dynamical system framework.Our study focuses on the coexistence problem,examining how different netw...This paper analyzes the dynamics of a two-strain symbiotic contact process on graphs using a discrete-time nonlinear dynamical system framework.Our study focuses on the coexistence problem,examining how different network topologies and co-infection dynamics affect the spread and persistence of both strains.We derive infection probabilities for each strain over time and demonstrate that the survival of the epidemic requires the epidemic threshold S>1 for at least one strain.This condition is shown to be necessary for the sustained propagation of the epidemic.Our findings provide insights into the role of symbiosis in multi-strain epidemic models on complex networks.展开更多
We investigate the contact process on random graphs generated from the configuration model for scale-free complex networks with the power law exponent β E （2, 3]. Using the neighborhood expansion method, we show tha...We investigate the contact process on random graphs generated from the configuration model for scale-free complex networks with the power law exponent β E （2, 3]. Using the neighborhood expansion method, we show that, with positive probability, any disease with an infection rate λ 〉 0 can survive for exponential time in the number of vertices of the graph. This strongly supports the view that stochastic scale-free networks are remarkably different from traditional regular graphs, such as, Z^d and classical Erdos-Renyi random graphs.展开更多
This paper is concerned with the contact process with random vertex weights on regular trees, and studies the asymptotic behavior of the critical infection rate as the degree of the trees increasing to infinity. In th...This paper is concerned with the contact process with random vertex weights on regular trees, and studies the asymptotic behavior of the critical infection rate as the degree of the trees increasing to infinity. In this model, the infection propagates through the edge connecting vertices x and y at rate λp（x）p（y） for someλ 〉0, where {ρ（x）, x∈ Td} are independent and identically distributed （i.i.d.） vertex weights. We show that when d is large enough, there is a phase transition at At（d）∈ （0, ec） such that for λ 〈 λc（d）, the contact process dies out, and for λ 〉 λc（d）, the contact process survives with a positive probability. Moreover, we also show that there is another phase transition at λe（d） such that for λ 〈 λe（d）, the contact process dies out at an exponential rate. Finally, we show that these two critical values have the same asymptotic behavior as d increases.展开更多
Flexible and wearable sensing devices have broad application prospects in bio-monitoring such as pulse measurement,motion detection and voice recognition.In recent years,many significant improvements had been made to ...Flexible and wearable sensing devices have broad application prospects in bio-monitoring such as pulse measurement,motion detection and voice recognition.In recent years,many significant improvements had been made to enhance the sensor’s performance including sensitivity,flexibility and repeatability.However,it is still extremely complicated and difficult to prepare a patterned sensor directly on a flexible substrate.Herein,inspired by typography,a lowcost,environmentally friendly stamping method for the mass production of transparent conductive carbon nanotube(CNT)film is proposed.In this dry transfer strategy,a porous CNT block was used as both the seal and the ink;and Ecoflex film was served as an object substrate.Welldesigned CNT patterns can be easily fabricated on the polymer substrate by engraving the target pattern on the CNT seal before the stamping process.Moreover,the CNT film can be directly used to fabricate ultrathin(300μm)strain sensor.This strain sensor possesses high sensitivity with a gauge factor(GF)up to 9960 at 85%strain,high stretchability(>200%)and repeatability(>5000 cycles).It has been used to measure pulse signals and detect joint motion,suggesting promising application prospects in flexible and wearable electronic devices.展开更多
Some techniques such as die surface description, contact judgement algorithm and remeshing are proposed to improve the robustness of the numerical solution. Based on these techniques, a three-dimensional rigid-plastic...Some techniques such as die surface description, contact judgement algorithm and remeshing are proposed to improve the robustness of the numerical solution. Based on these techniques, a three-dimensional rigid-plastic FEM code has been developed. Isothermal forging process of a cylindrical housing has been simulated. The simulation results show that the given techniques and the FEM code are reasonable and feasible for three-dimensional bulk forming processes.展开更多
In this paper we present new numerical simulation approaches for determining the energy processes under periodic conditions caused by time-discontinuous forces in the wheel-rail contacts. The main advantage of the pre...In this paper we present new numerical simulation approaches for determining the energy processes under periodic conditions caused by time-discontinuous forces in the wheel-rail contacts. The main advantage of the presented method is the total elimination of frequency analysis, which in effect introduces important simplifications in the identification of the effects in the contact. The second important feature is the fact that the method is based on the analysis of appropriate loops on the energy phase plane leading to an easy estimation of the rail strength through the evaluation of the loop’s area. That model based simulation in the applied dynamics relies on advanced methods for model setup, robust and efficient numerical solution techniques and powerful simulation tools for practical applications. Fundamental properties of contact displacements of the rail surface have been considered on the basis of the newly established method. The contact zone between railway wheels and the rail surfaces made of bulk materials is perceived as strong enough to resist the normal (vertical) forces introduced by heavy loads and the dynamic response induced by track and wheel irregularities. The analysis is carried out for a wheel running on an elastic rail rested on sleepers arranged on completely rigid foundation. The equations of displacement motion are established through the application of the Lagrange equations approach. The established model of the wheel-rail contact dynamics has been applied to that same roll plane but with taking into account a nonlinear characteristic of the sleeper with respect to the ground. Attention then is focused completely on the modeling of the energy absorbed by the rail. The applied method employs the energy state variables as time functions leading to determine the susceptibility of a given contact on the strength induced by the rail roll.展开更多
Al electrodes are well known as ohmic contact electrodes for the PTC component , the influence of their thickness on final component properties was investigated by comparing their ohmic characteristics with the ones ...Al electrodes are well known as ohmic contact electrodes for the PTC component , the influence of their thickness on final component properties was investigated by comparing their ohmic characteristics with the ones of InGa electrodes . After observing the Al paste physical and chemical behaviors during rising temperature by thermal analysis (DTA), the firing operation of Al electrodes could be divided into three main subsections: the temperature rising time (t-r), the peak firing temperature (T-p) and the hold time at peak firing temperature (t-h). The effects of these three parameters on final component properties were discussed in detail.展开更多
Mechanism of frictional vibration and the difference of kinctic-static friction is an open question. Research shows that the change of real area of contact during transition process of friction results in the phenomen...Mechanism of frictional vibration and the difference of kinctic-static friction is an open question. Research shows that the change of real area of contact during transition process of friction results in the phenomena mentioned above. In substance, the F-Vr, descent and F-T ascent characters are caused by A-Vr, and A-T characters respectively. Based on ultrasonic experiment the mechanism of the phenomena is explained and the frictional formulas using the parameter-real area of contact are given in this article.展开更多
This article proposes a framework, called BP-M* which includes: 1) a methodology to analyze, engineer, restructure and implement business processes, and 2) a process model that extends the process diagram with the spe...This article proposes a framework, called BP-M* which includes: 1) a methodology to analyze, engineer, restructure and implement business processes, and 2) a process model that extends the process diagram with the specification of resources that execute the process activities, allocation policies, schedules, times of activities, management of queues in input to the activities and workloads so that the same model can be simulated by a discrete event simulator. The BP-M* framework has been applied to a real case study, a public Contact Center which provides different typologies of answers to users’ requests. The simulation allows to study different system operating scenarios (“What-If” analysis) providing useful information for analysts to evaluate restructuring actions.展开更多
针对市场上的刚性健康监测设备无法贴合皮肤、降低了监测精度以及影响穿戴舒适性等问题,设计了一种基于聚偏氟乙烯(Polyvinylidene Fluoride,PVDF)柔性压电传感器的体征监测系统,以床垫作为载体放置在睡姿胸部正下方,利用高精度传感器...针对市场上的刚性健康监测设备无法贴合皮肤、降低了监测精度以及影响穿戴舒适性等问题,设计了一种基于聚偏氟乙烯(Polyvinylidene Fluoride,PVDF)柔性压电传感器的体征监测系统,以床垫作为载体放置在睡姿胸部正下方,利用高精度传感器及数据处理算法实时监测人体心率和呼吸率。系统以STM32F103为采集通信模块、Purple Pi RK3566为数据处理模块,通过EMD-FFT算法进行实时处理,通过SPI协议实现设备之间的通信。仿真及实测结果表明,该方案抗干扰性好,低频响应好且准确度高,可实现不同场景中体征的实时监测,为提高生活健康质量和生命健康指数提供有效支撑。展开更多
A Ti^4＋-doped nano-structured AgSnO2 material was prepared using sol-gel method and characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and scanning electron microscopy （SEM）. The ...A Ti^4＋-doped nano-structured AgSnO2 material was prepared using sol-gel method and characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and scanning electron microscopy （SEM）. The results show that Ti^4＋ cations are successfully doped into the crystal lattice of SnO2, and thus significantly improve the electrical conductivity of the sample. Furthermore, the coating of Ag on Ti^4＋-doped SnO2 nano-sized particles enhances the surface wettability and enables the resulting AgSnO2 material to have better mechanical properties.展开更多
One of the major advantages of utilizing atmospheric pressure plasma processing （APPP） technology to fabricate ultra-precision optics is that there is no subsurface damage during the process. In APPP, the removal fo...One of the major advantages of utilizing atmospheric pressure plasma processing （APPP） technology to fabricate ultra-precision optics is that there is no subsurface damage during the process. In APPP, the removal footprint and removal rate are critical to the capability and efficiency of the figuring of the optical surface. In this paper, an atmospheric plasma torch, which can work in both remote mode and contact mode, is presented. The footprints and the removal rates of both modes are compared by profilometer measurements. The influences of process recipes and substrate thickness for both modes are investigated through a series of experiments. When the substrate is thinner than 12 mm, the removal rate in contact mode is higher. However, the removal rate and width of the footprint decrease dramatically as the substrate thickness increases in contact mode.展开更多
基金Supported in part by the NNSF of China (10531070,10625101)the National Basic Research Program of China (2006CB805900)
文摘In this article, we discuss several properties of the basic contact process on hexagonal lattice H, showing that it behaves quite similar to the process on d-dimensional lattice Zd in many aspects. Firstly, we construct a coupling between the contact process on hexagonal lattice and the oriented percolation, and prove an equivalent finite space-time condition for the survival of the process. Secondly, we show the complete convergence theorem and the polynomial growth hold for the contact process on hexagonal lattice. Finally, we prove exponential bounds in the supercritical case and exponential decay rates in the subcritical case of the process.
基金Research was supported in part by Grant G1999075106 from the Ministry of Science and Technology of China.
文摘The author considers the contact process on a branching plane Td×Z, which is the product of a regular tree Td and the line Z. It is shown that above the second critical point, the complete convergence theory holds.
基金Supported in part by the National Natural Science Foundation of China.
文摘This paper shows that for a supercritical contact process in one dimension, if the initial distribution satisfies reasonable hypothesis, then the first hitting time of certain set with anomalous small density is asymptotically exponentially distributed. We also show the similar result for the contact process on the finite set [0, N].
基金supported by the Mathematics for Sustainable Development(MATH4SDG)project,which is a research and development project running in the period 2021-2026 at Makerere University-Uganda,University of Dar es Salaam-Tanzania,and the University of Bergen-Norway.
文摘This paper analyzes the dynamics of a two-strain symbiotic contact process on graphs using a discrete-time nonlinear dynamical system framework.Our study focuses on the coexistence problem,examining how different network topologies and co-infection dynamics affect the spread and persistence of both strains.We derive infection probabilities for each strain over time and demonstrate that the survival of the epidemic requires the epidemic threshold S>1 for at least one strain.This condition is shown to be necessary for the sustained propagation of the epidemic.Our findings provide insights into the role of symbiosis in multi-strain epidemic models on complex networks.
基金Partly supported by National Natural Science Foundation of China (Grant Nos. 10625101 and 10531070)the 973 Program of the Ministry of Science and Technology (Grant No. 2006CB805900)
文摘We investigate the contact process on random graphs generated from the configuration model for scale-free complex networks with the power law exponent β E （2, 3]. Using the neighborhood expansion method, we show that, with positive probability, any disease with an infection rate λ 〉 0 can survive for exponential time in the number of vertices of the graph. This strongly supports the view that stochastic scale-free networks are remarkably different from traditional regular graphs, such as, Z^d and classical Erdos-Renyi random graphs.
文摘This paper is concerned with the contact process with random vertex weights on regular trees, and studies the asymptotic behavior of the critical infection rate as the degree of the trees increasing to infinity. In this model, the infection propagates through the edge connecting vertices x and y at rate λp（x）p（y） for someλ 〉0, where {ρ（x）, x∈ Td} are independent and identically distributed （i.i.d.） vertex weights. We show that when d is large enough, there is a phase transition at At（d）∈ （0, ec） such that for λ 〈 λc（d）, the contact process dies out, and for λ 〉 λc（d）, the contact process survives with a positive probability. Moreover, we also show that there is another phase transition at λe（d） such that for λ 〈 λe（d）, the contact process dies out at an exponential rate. Finally, we show that these two critical values have the same asymptotic behavior as d increases.
基金financially supported by National Natural Science Foundation of China(Grant No.51772335)Guangdong Youth Top-notch Talent Support Program(No.2015TQ01C201)the Fundamental Research Funds for the Central Universities.
文摘Flexible and wearable sensing devices have broad application prospects in bio-monitoring such as pulse measurement,motion detection and voice recognition.In recent years,many significant improvements had been made to enhance the sensor’s performance including sensitivity,flexibility and repeatability.However,it is still extremely complicated and difficult to prepare a patterned sensor directly on a flexible substrate.Herein,inspired by typography,a lowcost,environmentally friendly stamping method for the mass production of transparent conductive carbon nanotube(CNT)film is proposed.In this dry transfer strategy,a porous CNT block was used as both the seal and the ink;and Ecoflex film was served as an object substrate.Welldesigned CNT patterns can be easily fabricated on the polymer substrate by engraving the target pattern on the CNT seal before the stamping process.Moreover,the CNT film can be directly used to fabricate ultrathin(300μm)strain sensor.This strain sensor possesses high sensitivity with a gauge factor(GF)up to 9960 at 85%strain,high stretchability(>200%)and repeatability(>5000 cycles).It has been used to measure pulse signals and detect joint motion,suggesting promising application prospects in flexible and wearable electronic devices.
基金This work was supported by the Brain Korea 2lProject and the Grallt of Post-Doc Program, KyungpookNational University (1999).
文摘Some techniques such as die surface description, contact judgement algorithm and remeshing are proposed to improve the robustness of the numerical solution. Based on these techniques, a three-dimensional rigid-plastic FEM code has been developed. Isothermal forging process of a cylindrical housing has been simulated. The simulation results show that the given techniques and the FEM code are reasonable and feasible for three-dimensional bulk forming processes.
文摘In this paper we present new numerical simulation approaches for determining the energy processes under periodic conditions caused by time-discontinuous forces in the wheel-rail contacts. The main advantage of the presented method is the total elimination of frequency analysis, which in effect introduces important simplifications in the identification of the effects in the contact. The second important feature is the fact that the method is based on the analysis of appropriate loops on the energy phase plane leading to an easy estimation of the rail strength through the evaluation of the loop’s area. That model based simulation in the applied dynamics relies on advanced methods for model setup, robust and efficient numerical solution techniques and powerful simulation tools for practical applications. Fundamental properties of contact displacements of the rail surface have been considered on the basis of the newly established method. The contact zone between railway wheels and the rail surfaces made of bulk materials is perceived as strong enough to resist the normal (vertical) forces introduced by heavy loads and the dynamic response induced by track and wheel irregularities. The analysis is carried out for a wheel running on an elastic rail rested on sleepers arranged on completely rigid foundation. The equations of displacement motion are established through the application of the Lagrange equations approach. The established model of the wheel-rail contact dynamics has been applied to that same roll plane but with taking into account a nonlinear characteristic of the sleeper with respect to the ground. Attention then is focused completely on the modeling of the energy absorbed by the rail. The applied method employs the energy state variables as time functions leading to determine the susceptibility of a given contact on the strength induced by the rail roll.
文摘Al electrodes are well known as ohmic contact electrodes for the PTC component , the influence of their thickness on final component properties was investigated by comparing their ohmic characteristics with the ones of InGa electrodes . After observing the Al paste physical and chemical behaviors during rising temperature by thermal analysis (DTA), the firing operation of Al electrodes could be divided into three main subsections: the temperature rising time (t-r), the peak firing temperature (T-p) and the hold time at peak firing temperature (t-h). The effects of these three parameters on final component properties were discussed in detail.
文摘Mechanism of frictional vibration and the difference of kinctic-static friction is an open question. Research shows that the change of real area of contact during transition process of friction results in the phenomena mentioned above. In substance, the F-Vr, descent and F-T ascent characters are caused by A-Vr, and A-T characters respectively. Based on ultrasonic experiment the mechanism of the phenomena is explained and the frictional formulas using the parameter-real area of contact are given in this article.
文摘This article proposes a framework, called BP-M* which includes: 1) a methodology to analyze, engineer, restructure and implement business processes, and 2) a process model that extends the process diagram with the specification of resources that execute the process activities, allocation policies, schedules, times of activities, management of queues in input to the activities and workloads so that the same model can be simulated by a discrete event simulator. The BP-M* framework has been applied to a real case study, a public Contact Center which provides different typologies of answers to users’ requests. The simulation allows to study different system operating scenarios (“What-If” analysis) providing useful information for analysts to evaluate restructuring actions.
文摘针对市场上的刚性健康监测设备无法贴合皮肤、降低了监测精度以及影响穿戴舒适性等问题,设计了一种基于聚偏氟乙烯(Polyvinylidene Fluoride,PVDF)柔性压电传感器的体征监测系统,以床垫作为载体放置在睡姿胸部正下方,利用高精度传感器及数据处理算法实时监测人体心率和呼吸率。系统以STM32F103为采集通信模块、Purple Pi RK3566为数据处理模块,通过EMD-FFT算法进行实时处理,通过SPI协议实现设备之间的通信。仿真及实测结果表明,该方案抗干扰性好,低频响应好且准确度高,可实现不同场景中体征的实时监测,为提高生活健康质量和生命健康指数提供有效支撑。
文摘A Ti^4＋-doped nano-structured AgSnO2 material was prepared using sol-gel method and characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and scanning electron microscopy （SEM）. The results show that Ti^4＋ cations are successfully doped into the crystal lattice of SnO2, and thus significantly improve the electrical conductivity of the sample. Furthermore, the coating of Ag on Ti^4＋-doped SnO2 nano-sized particles enhances the surface wettability and enables the resulting AgSnO2 material to have better mechanical properties.
基金supported by National Natural Science Foundation of China(Nos.51175123 and 51105112)National Science and Technology Major Project of China(No.2013ZX04006011-205)
文摘One of the major advantages of utilizing atmospheric pressure plasma processing （APPP） technology to fabricate ultra-precision optics is that there is no subsurface damage during the process. In APPP, the removal footprint and removal rate are critical to the capability and efficiency of the figuring of the optical surface. In this paper, an atmospheric plasma torch, which can work in both remote mode and contact mode, is presented. The footprints and the removal rates of both modes are compared by profilometer measurements. The influences of process recipes and substrate thickness for both modes are investigated through a series of experiments. When the substrate is thinner than 12 mm, the removal rate in contact mode is higher. However, the removal rate and width of the footprint decrease dramatically as the substrate thickness increases in contact mode.
