Raindrop size distribution (RSD) characteristics over the South China Sea (SCS) are examined with onboard Parsivel disdrometer measurements collected during marine surveys from 2012 to 2016. The observed rainfall is d...Raindrop size distribution (RSD) characteristics over the South China Sea (SCS) are examined with onboard Parsivel disdrometer measurements collected during marine surveys from 2012 to 2016. The observed rainfall is divided into premonsoon, monsoon, and post-monsoon periods based on the different large-scale circumstances. In addition to disdrometer data, sounding observation, FY-2E satellite, SPRINTARS (Spectral Radiation-Transport Model for Aerosol Species), and NCEP reanalysis datasets are used to illustrate the dynamical and microphysical characteristics associated with the rainfall in different periods. Significant variations have been observed in respect of raindrops among the three periods. Intercomparison reveals that small drops (D < 1 mm) are prevalent during pre-monsoon precipitation, whereas medium drops (1?3 mm) are predominant in monsoon precipitation. Overall, the post-monsoon precipitation is characterized by the least concentration of raindrops among the three periods. But, several large raindrops could also occur due to severe convective precipitation events in this period. Classification of the precipitation into stratiform and convective regimes shows that the lg(Nw) value of convective rainfall is the largest (smallest) in the pre-monsoon (post-monsoon) period, whereas the Dm value is the smallest (largest) in the pre-monsoon (post-monsoon) period. An inversion relationship between the coefficient A and the exponential b of the Z?R relationships for precipitation during the three periods is found. Empirical relations between Dm and the radar reflectivity factors at Ku and Ka bands are also derived to improve the rainfall retrieval algorithms over the SCS. Furthermore, the possible causative mechanisms for the significant RSD variability in different periods are also discussed with respect to warm and cold rain processes, raindrop evaporation, convective activities, and other meteorological factors.展开更多
Nano-scale titanium oxide memristors exhibit complex conductive characteristics, which have already been proved by existing research. One possible reason for this is that more than one mechanism exists, and together t...Nano-scale titanium oxide memristors exhibit complex conductive characteristics, which have already been proved by existing research. One possible reason for this is that more than one mechanism exists, and together they codetermine the conductive behaviors of the memristor. In this paper, we first analyze the theoretical base and conductive process of a memristor, and then propose a compatible circuit model to discuss and simulate the coexistence of the dopant drift and tunnel barrier-based mechanisms. Simulation results are given and compared with the published experimental data to prove the possibility of the coexistence. This work provides a practical model and some suggestions for studying the conductive mechanisms of memristors.展开更多
In many communication and signal routing applications, it is desirable to have a programmable analog filter. According to this practical demand, we consider the titanium oxide memristor, which is a kind of nano-scale ...In many communication and signal routing applications, it is desirable to have a programmable analog filter. According to this practical demand, we consider the titanium oxide memristor, which is a kind of nano-scale electron device with low power dissipation and nonvolatile memory. Such characteristics could be suitable for designing the desired filter. However, both the non-analytical relation between the memristance and the charges that pass through it, and the changeable V-I characteristics in physical tests make it difficult to accurately set the memristance to the target value. In this paper, the conductive mechanism of the memristor is analyzed, a method of continuously programming the memristance is proposed and simulated in a simulation program with integrated circuit emphasis, and its feasibility and compatibility, both in simu- lations and physical realizations, are demonstrated. This method is then utilized in a first-order active filter as an example to show its applications in programmable filters. This work also provides a practical tool for utilizing memristors as resistance programmable devices.展开更多
The recent published experimental data of titanium oxide memristor devices which are tested under the same experi- mental conditions exhibit the strange instability and complexity of these devices. Such undesired char...The recent published experimental data of titanium oxide memristor devices which are tested under the same experi- mental conditions exhibit the strange instability and complexity of these devices. Such undesired characteristics preclude the understanding of the device conductive processes and the memristor-based practical applications. The possibility of the coexistence of dopant drift and tunnel barrier conduction in a memristor provides preliminary explanations for the undesired characteristics. However, current research lacks detailed discussion about the coexistence case. In this paper, dopant drift and tunnel barrier-based theories are first analyzed for studying the relations between parameters and physical variables which affect characteristics of mernristors, and then the influences of each parameter change on the conductive behaviors in the single and coexistence cases of the two mechanisms are simulated and discussed respectively. The simulation results provide further explanations of the complex device conduction. Theoretical methods of eliminating or reducing the coex- istence of the two mechanisms are proposed, in order to increase the stability of the device conduction. This work also provides the support for optimizing the fabrications of memristor devices with excellent performance.展开更多
As a recognized classic of American TV series,“Friends”tells the complex story of friendship,love between six distinctive American young people.Different family backgrounds and childhood experiences presented in TV ...As a recognized classic of American TV series,“Friends”tells the complex story of friendship,love between six distinctive American young people.Different family backgrounds and childhood experiences presented in TV dramas take account for their difference in traits.Through the theoretical concept of psychoanalytic literature,this article attempts to reveal how the specific influence and manifestation of the family situation and parental behavior have on the character and behavior of the protagonist,as well as to further analyze how the trauma suffered in childhood functions in adult behavior.As adults,their behavior and habits are still constrained and influenced by their childhood experiences.展开更多
As a famous American writer,there have been many different opinions on whether Hemingway is a typical masculinist writer.Through a brief analysis of the feminist consciousness in Hemingway’s works and a detailed femi...As a famous American writer,there have been many different opinions on whether Hemingway is a typical masculinist writer.Through a brief analysis of the feminist consciousness in Hemingway’s works and a detailed feminist interpretation of“Cat in the Rain”,this paper holds that it is unfair and biased to stereotype Hemingway as a typical masculinist writer since there is a very strong feminist consciousness in his early works.展开更多
The formulas for atomic displacements and Hamiltonian of a thin crystal film in phonon occupation number representation are obtained with the aid of Green's function theory. On the basis of these results, the form...The formulas for atomic displacements and Hamiltonian of a thin crystal film in phonon occupation number representation are obtained with the aid of Green's function theory. On the basis of these results, the formulas for thermal expansion coefficients of the thin crystal film are derived with the perturbation theory, and the numerical calculations are carried out. The results show that the thinner films have larger thermal expansion coefficients.展开更多
A scramjet combustor with double cavitybased flameholders was experimentally studied in a directconnected test bed with the inflow conditions of M = 2.64,Pt = 1.84 MPa,Tt = 1 300 K.Successful ignition and selfsustaine...A scramjet combustor with double cavitybased flameholders was experimentally studied in a directconnected test bed with the inflow conditions of M = 2.64,Pt = 1.84 MPa,Tt = 1 300 K.Successful ignition and selfsustained combustion with room temperature kerosene was achieved using pilot hydrogen,and kerosene was vertically injected into the combustor through 4×φ 0.5 mm holes mounted on the wall.For different equivalence ratios and different injection schemes with both tandem cavities and parallel cavities,flow fields were obtained and compared using a high speed camera and a Schlieren system.Results revealed that the combustor inside the flow field was greatly influenced by the cavity installation scheme,cavities in tandem easily to form a single side flame distribution,and cavities in parallel are more likely to form a joint flame,forming a choked combustion mode.The supersonic combustion flame was a kind of diffusion flame and there were two kinds of combustion modes.In the unchoked combustion mode,both subsonic and supersonic combustion regions existed.While in the choked mode,the combustion region was fully subsonic with strong shock propagating upstream.Results also showed that there was a balance point between the boundary separation and shock enhanced combustion,depending on the intensity of heat release.展开更多
A one-dimensional radial non-uniform fluid model is employed to study plasma behaviors with special emphasis laid on helicon discharges. The plasma density ne, electron temperature Te, electron azimuthal and radial dr...A one-dimensional radial non-uniform fluid model is employed to study plasma behaviors with special emphasis laid on helicon discharges. The plasma density ne, electron temperature Te, electron azimuthal and radial drift velocities are investigated in terms of the plasma radius rp, magnetic field intensity B0 and gas pressure p0, by assuming radial ambipolar diffusion and negligible ion cyclotron movement. The results show that the magnetic confinement plays an important role in the discharge equilibrium, especially at low pressure, which significantly reduces Te compared with the case of a negligible magnetic field effect, and higher B0 leads to a greater average plasma density. Te shows little variations in the plasma density range of 1011 cm-3- 1013 cm-3 for p0 〈 3.0 mTorr. Comparison of the simulation results with experiments suggests that the model can make reasonable predictions of Te in low pressure helicon discharges.展开更多
It is a tough problem to jointly detect and track a weak target, and it becomes even more challenging when the target is maneuvering. The above problem is formulated by using the Bayesian theory and a multiple model(M...It is a tough problem to jointly detect and track a weak target, and it becomes even more challenging when the target is maneuvering. The above problem is formulated by using the Bayesian theory and a multiple model(MM) based filter is proposed. The filter presented uses the MM method to accommodate the multiple motions that a maneuvering target may travel under by adding a random variable representing the motion model to the target state. To strengthen the efficiency performance of the filter,the target existence variable is separated from the target state and the existence probability is calculated in a more efficient way. To examine the performance of the MM based approach, a typical track-before-detect(TBD) scenario with a maneuvering target is used for simulations. The simulation results indicate that the MM based filter proposed has a good performance in joint detecting and tracking of a weak and maneuvering target, and it is more efficient than the general MM method.展开更多
Wireless sensor networks (WSNs) are mainly characterized by their limited and non-replenishable energy supply. Hence, the energy efficiency of the infrastructure greatly affects the network lifetime. Clustering is one...Wireless sensor networks (WSNs) are mainly characterized by their limited and non-replenishable energy supply. Hence, the energy efficiency of the infrastructure greatly affects the network lifetime. Clustering is one of the methods that can expand the lifespan of the whole network by grouping the sensor nodes according to some criteria and choosing the appropriate cluster heads(CHs). The balanced load of the CHs has an important effect on the energy consumption balancing and lifespan of the whole network. Therefore, a new CHs election method is proposed using an adaptive discrete particle swarm optimization (ADPSO) algorithm with a fitness value function considering the load balancing and energy consumption. Simulation results not only demonstrate that the proposed algorithm can have better performance in load balancing than low-energy adaptive clustering hierarchy (LEACH), hybrid energy-efficient distributed clustering (HEED), and dynamic clustering algorithm with balanced load (DCBL), but also imply that the proposed algorithm can extend the network lifetime more.展开更多
We report 12.8 W supercontinuum generation with a high optical-to-optical conversion efficiency of up to 85%in an all-fiber device.This is achieved by using an all-fiber picosecond master oscillator power amplifier la...We report 12.8 W supercontinuum generation with a high optical-to-optical conversion efficiency of up to 85%in an all-fiber device.This is achieved by using an all-fiber picosecond master oscillator power amplifier laser,which has an output pigtail double clad fiber,to pump a 3-m photonic crystal fiber with the core at one end enlarged by adiabatically collapsing two inner layers of air holes while keeping other holes open.Our experimental results show that the short-wavelength generation is due to dispersive wave trapping by redshifted solitons.展开更多
In the process of protected protocol recognition,an improved AGglomerative NESting algorithm( IAGNES) with high adaptability is proposed,which is based on the AGglomerative NESting algorithm( AGNES),for the challengin...In the process of protected protocol recognition,an improved AGglomerative NESting algorithm( IAGNES) with high adaptability is proposed,which is based on the AGglomerative NESting algorithm( AGNES),for the challenging issue of how to obtain single protocol data frames from multiprotocol data frames. It can improve accuracy and efficiency by similarity between bit-stream data frames and clusters,extract clusters in the process of clustering. Every cluster obtained contains similarity evaluation index which is helpful to evaluation. More importantly,IAGNES algorithm can automatically recognize the number of cluster. Experiments on the data set published by Lincoln Laboratory shows that the algorithm can cluster the protocol data frames with high accuracy.展开更多
Cloud computing has been widely adopted by enterprises because of its on-demand and elastic resource usage paradigm. Currently most cloud applications are running on one single cloud. However, more and more applicatio...Cloud computing has been widely adopted by enterprises because of its on-demand and elastic resource usage paradigm. Currently most cloud applications are running on one single cloud. However, more and more applications demand to run across several clouds to satisfy the requirements like best cost efficiency, avoidance of vender lock-in, and geolocation sensitive service. JointCloud computing is a new research initiated by Chinese institutes to address the computing issues concerned with multiple clouds. In JointCloud, users' diverse and dynamic requirements on cloud resources axe satisfied by providing users virtual cloud (VC) for special purposes. A virtual cloud for special purposes is in essence a user's specific cloud working environment having the customized software stacks, configurations and computing resources readily available. This paper first introduces what is JointCloud computing and then describes the design rationales, motivation examples, mechanisms and enabling technologies of VC in JointCloud.展开更多
In this note we give a rather good approximate algorithm of optimal digit-grouped partition of sequences, showing that the optimal complete digit-grouped partition number of a dumbbell type sequence S is equal to its ...In this note we give a rather good approximate algorithm of optimal digit-grouped partition of sequences, showing that the optimal complete digit-grouped partition number of a dumbbell type sequence S is equal to its optimal digit-grouped partition number N(S), hence an estimation of N(S) is obtained. The thickness of a sequence introduced in this note is a key.展开更多
The current paper is devoted to stochastic Burgers equation with driving forcing given by white noise type in time and periodic in space. Motivated by the numerical results of Halter and Voss, we prove that the Burger...The current paper is devoted to stochastic Burgers equation with driving forcing given by white noise type in time and periodic in space. Motivated by the numerical results of Halter and Voss, we prove that the Burgers equation is stochastic stable in the sense that statistically steady regimes of :fluid flows of stochastic Burgers equation converge to that of determinstic Burgers equation as noise tends to zero.展开更多
The thermal entanglement in (1/2,1) mixed-spin Heisenberg XXZ model is investigated under an external nonuniform magnetic field. In the uniform magnetic field system,the critical magnetic field Bc and critical tempera...The thermal entanglement in (1/2,1) mixed-spin Heisenberg XXZ model is investigated under an external nonuniform magnetic field. In the uniform magnetic field system,the critical magnetic field Bc and critical temperature Tc are increased by increasing the anisotropic parameter k. The degree of magnetic field b plays an important role in improving the critical temperature and enlarging the region of entan-glement in the nonuniform magnetic field system.展开更多
The Global/Regional Assimilation and PrEdiction System(GRAPES)is a new-generation operational numerical weather prediction(NWP)model developed by the China Meteorological Administration(CMA).It is a grid-point m...The Global/Regional Assimilation and PrEdiction System(GRAPES)is a new-generation operational numerical weather prediction(NWP)model developed by the China Meteorological Administration(CMA).It is a grid-point model with a code structure different from that of spectral models used in other operational NWP centers such as the European Centre for Medium-Range Weather Forecasts(ECMWF),National Centers for Environmental Prediction(NCEP),and Japan Meteorological Agency(JMA),especially in the context of parallel computing.In the GRAPES global model,a semi-implicit semi-Lagrangian scheme is used for the discretization over a sphere,which requires careful planning for the busy communications between the arrays of processors,because the Lagrangian differential scheme results in shortened trajectories interpolated between the grid points at the poles and in the associated adjacent areas.This means that the latitude-longitude partitioning is more complex for the polar processors.Therefore,a parallel strategy with efficient computation,balanced load,and synchronous communication shall be developed.In this paper,a message passing approach based on MPI(Message Passing Interface)group communication is proposed.Its key-point is to group the polar processors in row with matrix-topology during the processor partitioning.A load balance task distribution algorithm is also discussed.Test runs on the IBM-cluster 1600 at CMA show that the new algorithm is of desired scalability,and the readjusted load balance scheme can reduce the absolute wall clock time by 10% or more.The quasi-operational runs of the model demonstrate that the wall clock time secured by the strategy meets the real-time needs of NWP operations.展开更多
基金primarily supported by the Chinese Beijige Open Research Fund for the Nanjing Joint Center of Atmospheric Research (Grant No. NJCAR 2018ZD03)the National Key Research and Development Program of China (2018YFC1507304)the National Natural Science Foundation of China (Grant Nos. 41575024 and 41865009)
文摘Raindrop size distribution (RSD) characteristics over the South China Sea (SCS) are examined with onboard Parsivel disdrometer measurements collected during marine surveys from 2012 to 2016. The observed rainfall is divided into premonsoon, monsoon, and post-monsoon periods based on the different large-scale circumstances. In addition to disdrometer data, sounding observation, FY-2E satellite, SPRINTARS (Spectral Radiation-Transport Model for Aerosol Species), and NCEP reanalysis datasets are used to illustrate the dynamical and microphysical characteristics associated with the rainfall in different periods. Significant variations have been observed in respect of raindrops among the three periods. Intercomparison reveals that small drops (D < 1 mm) are prevalent during pre-monsoon precipitation, whereas medium drops (1?3 mm) are predominant in monsoon precipitation. Overall, the post-monsoon precipitation is characterized by the least concentration of raindrops among the three periods. But, several large raindrops could also occur due to severe convective precipitation events in this period. Classification of the precipitation into stratiform and convective regimes shows that the lg(Nw) value of convective rainfall is the largest (smallest) in the pre-monsoon (post-monsoon) period, whereas the Dm value is the smallest (largest) in the pre-monsoon (post-monsoon) period. An inversion relationship between the coefficient A and the exponential b of the Z?R relationships for precipitation during the three periods is found. Empirical relations between Dm and the radar reflectivity factors at Ku and Ka bands are also derived to improve the rainfall retrieval algorithms over the SCS. Furthermore, the possible causative mechanisms for the significant RSD variability in different periods are also discussed with respect to warm and cold rain processes, raindrop evaporation, convective activities, and other meteorological factors.
基金supported by the National Natural Science Foundation of China(Grant No.61171017)
文摘Nano-scale titanium oxide memristors exhibit complex conductive characteristics, which have already been proved by existing research. One possible reason for this is that more than one mechanism exists, and together they codetermine the conductive behaviors of the memristor. In this paper, we first analyze the theoretical base and conductive process of a memristor, and then propose a compatible circuit model to discuss and simulate the coexistence of the dopant drift and tunnel barrier-based mechanisms. Simulation results are given and compared with the published experimental data to prove the possibility of the coexistence. This work provides a practical model and some suggestions for studying the conductive mechanisms of memristors.
基金supported by the National Natural Science Foundation of China(Grant Nos.61171017 and F010505)
文摘In many communication and signal routing applications, it is desirable to have a programmable analog filter. According to this practical demand, we consider the titanium oxide memristor, which is a kind of nano-scale electron device with low power dissipation and nonvolatile memory. Such characteristics could be suitable for designing the desired filter. However, both the non-analytical relation between the memristance and the charges that pass through it, and the changeable V-I characteristics in physical tests make it difficult to accurately set the memristance to the target value. In this paper, the conductive mechanism of the memristor is analyzed, a method of continuously programming the memristance is proposed and simulated in a simulation program with integrated circuit emphasis, and its feasibility and compatibility, both in simu- lations and physical realizations, are demonstrated. This method is then utilized in a first-order active filter as an example to show its applications in programmable filters. This work also provides a practical tool for utilizing memristors as resistance programmable devices.
基金supported by the National Natural Science Foundation of China(Grant No.61171017)
文摘The recent published experimental data of titanium oxide memristor devices which are tested under the same experi- mental conditions exhibit the strange instability and complexity of these devices. Such undesired characteristics preclude the understanding of the device conductive processes and the memristor-based practical applications. The possibility of the coexistence of dopant drift and tunnel barrier conduction in a memristor provides preliminary explanations for the undesired characteristics. However, current research lacks detailed discussion about the coexistence case. In this paper, dopant drift and tunnel barrier-based theories are first analyzed for studying the relations between parameters and physical variables which affect characteristics of mernristors, and then the influences of each parameter change on the conductive behaviors in the single and coexistence cases of the two mechanisms are simulated and discussed respectively. The simulation results provide further explanations of the complex device conduction. Theoretical methods of eliminating or reducing the coex- istence of the two mechanisms are proposed, in order to increase the stability of the device conduction. This work also provides the support for optimizing the fabrications of memristor devices with excellent performance.
文摘As a recognized classic of American TV series,“Friends”tells the complex story of friendship,love between six distinctive American young people.Different family backgrounds and childhood experiences presented in TV dramas take account for their difference in traits.Through the theoretical concept of psychoanalytic literature,this article attempts to reveal how the specific influence and manifestation of the family situation and parental behavior have on the character and behavior of the protagonist,as well as to further analyze how the trauma suffered in childhood functions in adult behavior.As adults,their behavior and habits are still constrained and influenced by their childhood experiences.
文摘As a famous American writer,there have been many different opinions on whether Hemingway is a typical masculinist writer.Through a brief analysis of the feminist consciousness in Hemingway’s works and a detailed feminist interpretation of“Cat in the Rain”,this paper holds that it is unfair and biased to stereotype Hemingway as a typical masculinist writer since there is a very strong feminist consciousness in his early works.
文摘The formulas for atomic displacements and Hamiltonian of a thin crystal film in phonon occupation number representation are obtained with the aid of Green's function theory. On the basis of these results, the formulas for thermal expansion coefficients of the thin crystal film are derived with the perturbation theory, and the numerical calculations are carried out. The results show that the thinner films have larger thermal expansion coefficients.
文摘A scramjet combustor with double cavitybased flameholders was experimentally studied in a directconnected test bed with the inflow conditions of M = 2.64,Pt = 1.84 MPa,Tt = 1 300 K.Successful ignition and selfsustained combustion with room temperature kerosene was achieved using pilot hydrogen,and kerosene was vertically injected into the combustor through 4×φ 0.5 mm holes mounted on the wall.For different equivalence ratios and different injection schemes with both tandem cavities and parallel cavities,flow fields were obtained and compared using a high speed camera and a Schlieren system.Results revealed that the combustor inside the flow field was greatly influenced by the cavity installation scheme,cavities in tandem easily to form a single side flame distribution,and cavities in parallel are more likely to form a joint flame,forming a choked combustion mode.The supersonic combustion flame was a kind of diffusion flame and there were two kinds of combustion modes.In the unchoked combustion mode,both subsonic and supersonic combustion regions existed.While in the choked mode,the combustion region was fully subsonic with strong shock propagating upstream.Results also showed that there was a balance point between the boundary separation and shock enhanced combustion,depending on the intensity of heat release.
文摘A one-dimensional radial non-uniform fluid model is employed to study plasma behaviors with special emphasis laid on helicon discharges. The plasma density ne, electron temperature Te, electron azimuthal and radial drift velocities are investigated in terms of the plasma radius rp, magnetic field intensity B0 and gas pressure p0, by assuming radial ambipolar diffusion and negligible ion cyclotron movement. The results show that the magnetic confinement plays an important role in the discharge equilibrium, especially at low pressure, which significantly reduces Te compared with the case of a negligible magnetic field effect, and higher B0 leads to a greater average plasma density. Te shows little variations in the plasma density range of 1011 cm-3- 1013 cm-3 for p0 〈 3.0 mTorr. Comparison of the simulation results with experiments suggests that the model can make reasonable predictions of Te in low pressure helicon discharges.
基金supported by the Natural Science Foundation of Anhui Province(1708085QF149)。
文摘It is a tough problem to jointly detect and track a weak target, and it becomes even more challenging when the target is maneuvering. The above problem is formulated by using the Bayesian theory and a multiple model(MM) based filter is proposed. The filter presented uses the MM method to accommodate the multiple motions that a maneuvering target may travel under by adding a random variable representing the motion model to the target state. To strengthen the efficiency performance of the filter,the target existence variable is separated from the target state and the existence probability is calculated in a more efficient way. To examine the performance of the MM based approach, a typical track-before-detect(TBD) scenario with a maneuvering target is used for simulations. The simulation results indicate that the MM based filter proposed has a good performance in joint detecting and tracking of a weak and maneuvering target, and it is more efficient than the general MM method.
基金National Natural Science Foundations of China(No. 61103175,No. 11141005)Technology Innovation Platform Project of Fujian Province,China (No. 2009J1007)+1 种基金Key Project Development Foundation of Education Committee of Fujian Province,China (No.JA11011)Project Development Foundations of Fuzhou University,China (No. 2010-XQ-21,No. XRC-1037)
文摘Wireless sensor networks (WSNs) are mainly characterized by their limited and non-replenishable energy supply. Hence, the energy efficiency of the infrastructure greatly affects the network lifetime. Clustering is one of the methods that can expand the lifespan of the whole network by grouping the sensor nodes according to some criteria and choosing the appropriate cluster heads(CHs). The balanced load of the CHs has an important effect on the energy consumption balancing and lifespan of the whole network. Therefore, a new CHs election method is proposed using an adaptive discrete particle swarm optimization (ADPSO) algorithm with a fitness value function considering the load balancing and energy consumption. Simulation results not only demonstrate that the proposed algorithm can have better performance in load balancing than low-energy adaptive clustering hierarchy (LEACH), hybrid energy-efficient distributed clustering (HEED), and dynamic clustering algorithm with balanced load (DCBL), but also imply that the proposed algorithm can extend the network lifetime more.
基金by the National Natural Science Foundation of China under Grant Nos 61077076 and 61007037the Program for New Century Excellent Talents in University under Grant No NCET-08-0142.
文摘We report 12.8 W supercontinuum generation with a high optical-to-optical conversion efficiency of up to 85%in an all-fiber device.This is achieved by using an all-fiber picosecond master oscillator power amplifier laser,which has an output pigtail double clad fiber,to pump a 3-m photonic crystal fiber with the core at one end enlarged by adiabatically collapsing two inner layers of air holes while keeping other holes open.Our experimental results show that the short-wavelength generation is due to dispersive wave trapping by redshifted solitons.
基金Supported by the National Natural Science Foundation of China(No.F020704)
文摘In the process of protected protocol recognition,an improved AGglomerative NESting algorithm( IAGNES) with high adaptability is proposed,which is based on the AGglomerative NESting algorithm( AGNES),for the challenging issue of how to obtain single protocol data frames from multiprotocol data frames. It can improve accuracy and efficiency by similarity between bit-stream data frames and clusters,extract clusters in the process of clustering. Every cluster obtained contains similarity evaluation index which is helpful to evaluation. More importantly,IAGNES algorithm can automatically recognize the number of cluster. Experiments on the data set published by Lincoln Laboratory shows that the algorithm can cluster the protocol data frames with high accuracy.
基金This work is supported by the National Key Research and Development Program of China under Grant No. 2016YFB1000105 and the National Natural Science Foundation of China under Grant Nos. 61272154 and 61421091.
文摘Cloud computing has been widely adopted by enterprises because of its on-demand and elastic resource usage paradigm. Currently most cloud applications are running on one single cloud. However, more and more applications demand to run across several clouds to satisfy the requirements like best cost efficiency, avoidance of vender lock-in, and geolocation sensitive service. JointCloud computing is a new research initiated by Chinese institutes to address the computing issues concerned with multiple clouds. In JointCloud, users' diverse and dynamic requirements on cloud resources axe satisfied by providing users virtual cloud (VC) for special purposes. A virtual cloud for special purposes is in essence a user's specific cloud working environment having the customized software stacks, configurations and computing resources readily available. This paper first introduces what is JointCloud computing and then describes the design rationales, motivation examples, mechanisms and enabling technologies of VC in JointCloud.
文摘In this note we give a rather good approximate algorithm of optimal digit-grouped partition of sequences, showing that the optimal complete digit-grouped partition number of a dumbbell type sequence S is equal to its optimal digit-grouped partition number N(S), hence an estimation of N(S) is obtained. The thickness of a sequence introduced in this note is a key.
基金Supported by NSF of China(Grant Nos.11101427,11371367)Fundamental program of NUDT
文摘The current paper is devoted to stochastic Burgers equation with driving forcing given by white noise type in time and periodic in space. Motivated by the numerical results of Halter and Voss, we prove that the Burgers equation is stochastic stable in the sense that statistically steady regimes of :fluid flows of stochastic Burgers equation converge to that of determinstic Burgers equation as noise tends to zero.
基金Supported by the National Natural Science Foundation of China (Grant No. 60607013)
文摘The thermal entanglement in (1/2,1) mixed-spin Heisenberg XXZ model is investigated under an external nonuniform magnetic field. In the uniform magnetic field system,the critical magnetic field Bc and critical temperature Tc are increased by increasing the anisotropic parameter k. The degree of magnetic field b plays an important role in improving the critical temperature and enlarging the region of entan-glement in the nonuniform magnetic field system.
基金Supported by the National S&T Infrastructure Program for the 11th Five-Year Period under Grant No.2006BAC02B00the National Natural Science Foundation of China under Grant Nos.40575050 and 40775073
文摘The Global/Regional Assimilation and PrEdiction System(GRAPES)is a new-generation operational numerical weather prediction(NWP)model developed by the China Meteorological Administration(CMA).It is a grid-point model with a code structure different from that of spectral models used in other operational NWP centers such as the European Centre for Medium-Range Weather Forecasts(ECMWF),National Centers for Environmental Prediction(NCEP),and Japan Meteorological Agency(JMA),especially in the context of parallel computing.In the GRAPES global model,a semi-implicit semi-Lagrangian scheme is used for the discretization over a sphere,which requires careful planning for the busy communications between the arrays of processors,because the Lagrangian differential scheme results in shortened trajectories interpolated between the grid points at the poles and in the associated adjacent areas.This means that the latitude-longitude partitioning is more complex for the polar processors.Therefore,a parallel strategy with efficient computation,balanced load,and synchronous communication shall be developed.In this paper,a message passing approach based on MPI(Message Passing Interface)group communication is proposed.Its key-point is to group the polar processors in row with matrix-topology during the processor partitioning.A load balance task distribution algorithm is also discussed.Test runs on the IBM-cluster 1600 at CMA show that the new algorithm is of desired scalability,and the readjusted load balance scheme can reduce the absolute wall clock time by 10% or more.The quasi-operational runs of the model demonstrate that the wall clock time secured by the strategy meets the real-time needs of NWP operations.