[Objective] This study aimed to provide referential basis for ecosystem study of Hebei Province in the new decade of 21st century, by investigating the correlation between natural subsystem and economic subsystem. [Me...[Objective] This study aimed to provide referential basis for ecosystem study of Hebei Province in the new decade of 21st century, by investigating the correlation between natural subsystem and economic subsystem. [Method] The correlation between natural subsystem and economic subsystem in ecosystem was discussed by means of the canonical correlation, and the correlation between variables was explored with statistical data. [Result] The canonical correlation between the two subsystems could be explained by three groups of typical variables, Le., the canonical correlation between crop production and consumption; the canonical correlation between agricultural crop production, aquaculture and scientific research development funds; and the canonical correlation between forest area and GDP per capita. With the growth of economy and revenue and the steady development of agricultural production, there are still some serious problems, including the change of residents consumption is out of proportion to its material consumption; the socio-economic development depends on consuming of forests more heavily, which destroy the balance between the economic growth and environmental protection. [Conclusion] The results provide referential basis for the ecosystem study of Hebei Province.展开更多
Unmanned vehicle has attracted wide attention and interests throughout the world since it first deputed in the 1960s. However, the experimental methods for unmanned vehicle's intelligent behavior, such as semi-physic...Unmanned vehicle has attracted wide attention and interests throughout the world since it first deputed in the 1960s. However, the experimental methods for unmanned vehicle's intelligent behavior, such as semi-physical simulation and motion subsystem, have not been widely explored. First, the requirements of the motion subsystem in unmanned vehicle semi-physical facility are analyzed, and a six DOF parallel manipulator is selected to reproduce the pose of the vehicle. The link lengths of the motion subsystem are worked out under the given rotational angles of the vehicle. According to the geometric properties of tetrahedron, three joint positions of the top platform are determined, and the rest are obtained from the first three position vectors. Six constraint equations are set up based on the vertices on the top platform and the link lengths. In order to solve the six angle variables, a numerical algorithm built on the Newton-Raphson iterative method is presented, which is based on Taylor series expansion of six constraint equations. The pose of the top platform is ultimately calculated. The eigenvalues of the top platform are solved to obtain the natural frequencies of the motion subsystem. The coordinates of six joint centers on the top platform and six constraint equations can be realized by simple algebraic manipulation, which allows significant abbreviation in the formulation and provides a systematic way of obtaining the kinematic solution of the parallel manipulator. A numerical example is given and its efficacy is demonstrated by the inverse kinematics. The computation strategy based on tetrahedron method and Newton-Raphson iterative method provide a simple and cost-effective method for solving forward kinematics of six DOF parallel manipulators, and this method sheds light on other parallel manipulators.展开更多
A useful life prediction method based on the integration of the stochastic hybrid automata(SHA) model and the frame of the dynamic fault tree(DFT) is proposed. The SHA model can incorporate the orbit environment, work...A useful life prediction method based on the integration of the stochastic hybrid automata(SHA) model and the frame of the dynamic fault tree(DFT) is proposed. The SHA model can incorporate the orbit environment, work modes, system configuration, dynamic probabilities and degeneration of components,as well as spacecraft dynamics and kinematics. By introducing the frame of DFT, the system is classified into several layers, and the problem of state combination explosion is artfully overcome.An improved dynamic reliability model(DRM) based on the Nelson hypothesis is investigated to improve the defect of cumulative failure probability(CFP), which is used to address the failure probability of components in the SHA model. The simulation using the Monte-Carlo method is finally conducted on two satellites, which are deployed with the same multi-gyro subsystem but run on different orbits. The results show that the predicted useful life of the attitude control system(ACS) with consideration of abrupt failure,degradation, and running environment is quite different between the two satellites.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
One of the most important features of modern minor satellites is to realize autonomous moving. The performance of the satellite autonomous computer operating system acting as the control center is utmost important. Th...One of the most important features of modern minor satellites is to realize autonomous moving. The performance of the satellite autonomous computer operating system acting as the control center is utmost important. The recent trend in operating system development is adopting microkernel architecture which holds such advantages as microminiaturization, modularity, portability and extendibility. The performance of I/O subsystem is currently receiving considerable research attention. Object-orientation offers an approach to application development in which software system can be constructed by composing and refining the pre-designed plug-compatible software components.It also starts with some basic notions fairly well accepted in computer science, namely encapsulation and reuse. In this paper, a new object-oriented real-time I/O subsystem model has been designed.In this model, the traditional I/O subsystem framework is discarded and a stream mechanism based on the object-oriented concept is introduced. In addition, the I/O requests are classified according to their time emergency to obtain real-time performance. So, this model meets such satelliteperformance requirements as reliability, flexibility, portability and real-time performance.展开更多
In recent years, the application of the Internet of Things (IoT) has become an emerging business. The most important concept of next-generation network for providing a common global IT platform is combining seamless...In recent years, the application of the Internet of Things (IoT) has become an emerging business. The most important concept of next-generation network for providing a common global IT platform is combining seamless networks and networked things, objects or sensors. Also, wireless body area networks (WBANs) are becoming mature with the widespread usage of the IoT. In order to support WBAN, the platform, scenario and emergency service are necessary due to the sensors in WBAN being related to wearer's life. The sensors on the body detect a lot of information about bioinformatics and medical signals, such as heartbeat and blood. Thus, the integration of IoT and network communication in daily life is important. However, there is not only a lack of common fabric for integrating IoT with current Internet and but also no emergency call process in the current network communication envi-ronment. To overcome such situations, the prototype of integrating IoT and emergency call process is discussed. A simulated boot-strap platform to provide the discussion of open challenges and solutions for deploying IoT in Internet and the emergency commu-nication system are analyzed by using a service of 3GPP IP multimedia subsystem. Finally, the prototype for supporting WBAN with emergence service is also addressed and the performance results are useful to service providers and network operators that they can estimate their migration to IoT by referring to this experience and experiment results. Furthermore, the queuing model used to achieve the performance of emergency service in IMS and the delay time of the proposed model is analyzed.展开更多
The general classification of information systems of remote action, including such system as positioning systems, location systems and remote sensing systems is suggested. In view of formulated limitation conditions t...The general classification of information systems of remote action, including such system as positioning systems, location systems and remote sensing systems is suggested. In view of formulated limitation conditions the common mathematical information model of data transfer subsystems of considered systems is suggested. The optimization of developed information model is carried out and the optimal operation regimes of these data transfer subsystems are展开更多
This paper presents a method for determining the reliability index of a subsystem in the materiel demonstration phase-AHP Failure Rate Method. It fully considers the various factors which influence a subsystem reliabi...This paper presents a method for determining the reliability index of a subsystem in the materiel demonstration phase-AHP Failure Rate Method. It fully considers the various factors which influence a subsystem reliability index and solves a difficult problem that puzzles the demonstration personnel.展开更多
The singularly perturbed bifurcation subsystem is described, and the test conditions of subsystem persistence are deduced. By use of fast and slow reduced subsystem model, the result does not require performing nonlin...The singularly perturbed bifurcation subsystem is described, and the test conditions of subsystem persistence are deduced. By use of fast and slow reduced subsystem model, the result does not require performing nonlinear transformation. Moreover, it is shown and proved that the persistence of the periodic orbits for Hopf bifurcation in the reduced model through center manifold. Van der Pol oscillator circuit is given to illustrate the persistence of bifurcation subsystems with the full dynamic system.展开更多
Three groups of cylinder specimens(φ10 mm×10 mm)with 20%,30%and 40%(by mass,the same hereinafter)of ZrO2,were prepared using analytically pure MgO,Al2O3 and ZrO2 powders as the starting materials.The specimens w...Three groups of cylinder specimens(φ10 mm×10 mm)with 20%,30%and 40%(by mass,the same hereinafter)of ZrO2,were prepared using analytically pure MgO,Al2O3 and ZrO2 powders as the starting materials.The specimens were fired at 1600℃for 5 h,1700℃for 0 h and 1800℃for 7 h,respectively.The microstructure of the MgO-MgAl2O4-ZrO2 subsystem was studied by FESEM.The results show that(1)in the temperature range of 1600-1700℃,solid phase reactions happen in the MgO-MgAl2O4-ZrO2 subsystem,leaving three phases:periclase,spinel and ZrO2(solid dissolving with Mg2+)co-existing;spinellization affects the densification;(2)the specimen with 40%ZrO2 fired at 1800℃has heterogeneous melting microstructure;some areas form typical ternary eutectic MgO-MgAl2O4-ZrO2 with composition of MgO 35.2%-37.2%,Al2O324.2%-26.6%,and ZrO237.2%-39.8%.展开更多
The controllability of delay degenerate differential control systems is discussed. Firstly, delay degenerate differential control system was transformed to be canonical form, and the connected terms were gotten rid of...The controllability of delay degenerate differential control systems is discussed. Firstly, delay degenerate differential control system was transformed to be canonical form, and the connected terms were gotten rid of, had delay degenerate differential control systems with independent subsystems. For the general delay degenerate differnetial control systems, it was gotten that the necessary and sufficient condition of that they are controllable is that their reachable set is equal to the whole space. For the delay degenerate differential control systems with independent subsystems, it was gotten that the necessary and sufficient conditions of that they are controllable are that their reachable sets are equal to their corresponding subspaces. Then some algebra criteria were gotten. Finally, an example was given to illustrate the main results.展开更多
For a Lie triple system T over a field of characteristic zero, some sufficient conditions for T to be two-generated are proved. We also discuss to what extent the two-generated subsystems determine the structure of th...For a Lie triple system T over a field of characteristic zero, some sufficient conditions for T to be two-generated are proved. We also discuss to what extent the two-generated subsystems determine the structure of the system T . One of the main results is that T is solvable if and only if every two elements generates a solvable subsystem. In fact, we give an explicit two-generated law for the two-generated subsystems.展开更多
In this paper, the dynamics of rule 106, a Chua’s hyper Bernoulli cellular automata rule, is studied and discussed from the viewpoint of symbolic dynamics. It is presented that rule 106 defines a chaotic subsystem wh...In this paper, the dynamics of rule 106, a Chua’s hyper Bernoulli cellular automata rule, is studied and discussed from the viewpoint of symbolic dynamics. It is presented that rule 106 defines a chaotic subsystem which is topologically mixing and possesses the positive topologically entropy. An effective method of constructing its chaotic subsystems is proposed. Indeed, it is interesting to find that this rule is filled with infinitely many disjoint chaotic subsystems. Special attention is paid to each subsystem on which rule 106 is topologically mixing and possesses the positive topologically entropy. Therefore, it is natural to argue that the intrinsic complexity of rule 106 is high from this viewpoint.展开更多
In this study,the relationship between the subsystems of Asian summer monsoon is analyzed using U.S.National Centers for Environmental Protection/National Center for Atmospheric Research reanalysis and Climate Predict...In this study,the relationship between the subsystems of Asian summer monsoon is analyzed using U.S.National Centers for Environmental Protection/National Center for Atmospheric Research reanalysis and Climate Prediction Center Merged Analysis of Precipitation monthly mean precipitation data.The results showed that there is significant correlation between the subsystems of Asian summer monsoon.The changes of intensity over the same period show that weak large-scale Asian monsoon,Southeast Asia monsoon and South Asian monsoon are associated with strong East Asian monsoon and decreasing rainfall in related areas.And when the large-scale Asian monsoon is strong,Southeast Asia and South Asia monsoons will be strong and precipitation will increase.While the Southeast Asia monsoon is strong,the South Asia monsoon is weak and the rainfall of South Asia is decreasing,and vice versa.The various subsystems are significantly correlated for all periods of intensity changes.展开更多
The subsystem synthesis method has been developed in order to improve computational efficiency for a multibody vehicle dynamics model. Using the subsystem synthesis method, equations of motion of the base body and eac...The subsystem synthesis method has been developed in order to improve computational efficiency for a multibody vehicle dynamics model. Using the subsystem synthesis method, equations of motion of the base body and each subsystem can be solved separately. In the subsystem synthesis method, various coordinate systems can be used and various integration methods can be applied in each subsystem, as long as the effective mass matrix and the effective force vector are properly produced. In this paper, comparative study has been carried out for the subsystem synthesis method with Cartesian coordinates and with joint relative coordinates. Two different integration methods such as an explicit integrator and an explicit implicit integrator are employed. In order to see the accuracy and computational efficiency from the different models based on the different coordinate systems and different integration methods, a rough terrain run simulations has been carried out with a 6 × 6 off-road multibody vehicle model.展开更多
A reliability-growth test is often used to assess complex systems under development.Reliability-growth models are usually used to quantify the achievable reliability indices and predict the expected reliability values...A reliability-growth test is often used to assess complex systems under development.Reliability-growth models are usually used to quantify the achievable reliability indices and predict the expected reliability values.The Crow army-materiel-system-analysis-activity(Crow-AMSAA)projection model and the AMSAA maturity projection(AMPM)-Stein model are suitable for modelling delayed corrective strategies.The AMPM-Stein model,which involves more failure data and requires limited assumptions,is more robust than the Crow-AMSAA projection model.However,the rationality of the Stein factor introduced in the AMPM-Stein model has always been controversial.An AMPM-Stein extended projection model,derived from data regrouping based on similar failure mechanisms,is presented to alleviate the problem.The study demonstrated that the proposed model performed well,the prediction results were credible,and the robustness of the proposed model was examined.Furthermore,the Stein-shrinkage factors,which are derived from components with similar inherent failure mechanisms,are easier to understand and accept in the field of engineering.An example shows that the proposed model is more suitable and accurate than the Crow-AMSAA model and the AMPM-Stein model,by comparing the projection values based on the failure data of the previous phases with the actual values of the current phases.This study provides a technical basis for extensive applications of the proposed model.展开更多
The Network Attachment Subsystem (NASS) is introduced to the Next Generation Network (NGN) architecture to enable services independent from access networks and support nomadism for fixed terminals. The NASS is respons...The Network Attachment Subsystem (NASS) is introduced to the Next Generation Network (NGN) architecture to enable services independent from access networks and support nomadism for fixed terminals. The NASS is responsible for managing the users attached to the access network in terms of user authentication, allocation of the IP address, and location management. In NGN R1, Telecommunications and Internet Converged Services and Protocols for Advanced Networking (TISPAN) studied the internal architecture and external interface protocols of NASS and published the relevant technical specifications. In NGN R2, TISPAN focuses on the study of mobility and nomadism as well as the ability to support various access network architectures. There still remain several issues that need further study.展开更多
The perspective of internal structure of the decision making units (DMUs) was considered as the “black box” when employing data envelopment analysis (DEA) models. However, in the actual world there are always some D...The perspective of internal structure of the decision making units (DMUs) was considered as the “black box” when employing data envelopment analysis (DEA) models. However, in the actual world there are always some DMUs that are composed of several sub-units or subsystems, each utilizes the same inputs to generate same outputs. Numerous instances can be listed, such as a firm with a few of plants. In this paper we present models that evaluated the efficiency of DMU which is comprised of same several parallel subsystems, the foremost contribution of our work is that we take the different importance of the subsystems into account in the model, which can be obviously distinguished to the existing DEA model. Secondly, since the alternative optimal multipliers may emerge in the model, the efficiency of each subsystem may be non-unique and we simultaneously develop models of efficiency decomposition for each subsystem. At last a case of technological innovation activities of each province in China is used as an example to state the models.展开更多
A two-dimensional Ising square lattice is modeled as a nano-size block array to study by Monte Carlo simulation the magnetic thermal stability of nano-structure magnetic media for data storage, thereon in the blocks J...A two-dimensional Ising square lattice is modeled as a nano-size block array to study by Monte Carlo simulation the magnetic thermal stability of nano-structure magnetic media for data storage, thereon in the blocks J1 > 0 is assigned for the interaction of a pair of nearest-neighbor spins, while 0 J0 J1 for that in regions between the blocks and (J0 + J1)/2 for the nearest-neighbor pairs with one in the block and the other one out of but near-most the block. We show that the magnetic thermal stability of the block accrues with the increase of J1 and with the decrease of J1 - J0 for a given J1, but contrarily, the anchoring ability for the initial magnetic orientation in nano-size block trails off as J1 - J0 diminish. This phenomena and size dependence of such anchoring ability are discussed in detail.展开更多
文摘[Objective] This study aimed to provide referential basis for ecosystem study of Hebei Province in the new decade of 21st century, by investigating the correlation between natural subsystem and economic subsystem. [Method] The correlation between natural subsystem and economic subsystem in ecosystem was discussed by means of the canonical correlation, and the correlation between variables was explored with statistical data. [Result] The canonical correlation between the two subsystems could be explained by three groups of typical variables, Le., the canonical correlation between crop production and consumption; the canonical correlation between agricultural crop production, aquaculture and scientific research development funds; and the canonical correlation between forest area and GDP per capita. With the growth of economy and revenue and the steady development of agricultural production, there are still some serious problems, including the change of residents consumption is out of proportion to its material consumption; the socio-economic development depends on consuming of forests more heavily, which destroy the balance between the economic growth and environmental protection. [Conclusion] The results provide referential basis for the ecosystem study of Hebei Province.
基金supported by National Natural Science Foundation of China (Grant No. 50908222)
文摘Unmanned vehicle has attracted wide attention and interests throughout the world since it first deputed in the 1960s. However, the experimental methods for unmanned vehicle's intelligent behavior, such as semi-physical simulation and motion subsystem, have not been widely explored. First, the requirements of the motion subsystem in unmanned vehicle semi-physical facility are analyzed, and a six DOF parallel manipulator is selected to reproduce the pose of the vehicle. The link lengths of the motion subsystem are worked out under the given rotational angles of the vehicle. According to the geometric properties of tetrahedron, three joint positions of the top platform are determined, and the rest are obtained from the first three position vectors. Six constraint equations are set up based on the vertices on the top platform and the link lengths. In order to solve the six angle variables, a numerical algorithm built on the Newton-Raphson iterative method is presented, which is based on Taylor series expansion of six constraint equations. The pose of the top platform is ultimately calculated. The eigenvalues of the top platform are solved to obtain the natural frequencies of the motion subsystem. The coordinates of six joint centers on the top platform and six constraint equations can be realized by simple algebraic manipulation, which allows significant abbreviation in the formulation and provides a systematic way of obtaining the kinematic solution of the parallel manipulator. A numerical example is given and its efficacy is demonstrated by the inverse kinematics. The computation strategy based on tetrahedron method and Newton-Raphson iterative method provide a simple and cost-effective method for solving forward kinematics of six DOF parallel manipulators, and this method sheds light on other parallel manipulators.
基金supported by the Fundamental Research Funds for the Central Universities(2016083)
文摘A useful life prediction method based on the integration of the stochastic hybrid automata(SHA) model and the frame of the dynamic fault tree(DFT) is proposed. The SHA model can incorporate the orbit environment, work modes, system configuration, dynamic probabilities and degeneration of components,as well as spacecraft dynamics and kinematics. By introducing the frame of DFT, the system is classified into several layers, and the problem of state combination explosion is artfully overcome.An improved dynamic reliability model(DRM) based on the Nelson hypothesis is investigated to improve the defect of cumulative failure probability(CFP), which is used to address the failure probability of components in the SHA model. The simulation using the Monte-Carlo method is finally conducted on two satellites, which are deployed with the same multi-gyro subsystem but run on different orbits. The results show that the predicted useful life of the attitude control system(ACS) with consideration of abrupt failure,degradation, and running environment is quite different between the two satellites.
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One of the most important features of modern minor satellites is to realize autonomous moving. The performance of the satellite autonomous computer operating system acting as the control center is utmost important. The recent trend in operating system development is adopting microkernel architecture which holds such advantages as microminiaturization, modularity, portability and extendibility. The performance of I/O subsystem is currently receiving considerable research attention. Object-orientation offers an approach to application development in which software system can be constructed by composing and refining the pre-designed plug-compatible software components.It also starts with some basic notions fairly well accepted in computer science, namely encapsulation and reuse. In this paper, a new object-oriented real-time I/O subsystem model has been designed.In this model, the traditional I/O subsystem framework is discarded and a stream mechanism based on the object-oriented concept is introduced. In addition, the I/O requests are classified according to their time emergency to obtain real-time performance. So, this model meets such satelliteperformance requirements as reliability, flexibility, portability and real-time performance.
基金partly funded by Ministry of Science and Technology of R.O.C. under grants no.NSC 101-2221-E-197008-MY3
文摘In recent years, the application of the Internet of Things (IoT) has become an emerging business. The most important concept of next-generation network for providing a common global IT platform is combining seamless networks and networked things, objects or sensors. Also, wireless body area networks (WBANs) are becoming mature with the widespread usage of the IoT. In order to support WBAN, the platform, scenario and emergency service are necessary due to the sensors in WBAN being related to wearer's life. The sensors on the body detect a lot of information about bioinformatics and medical signals, such as heartbeat and blood. Thus, the integration of IoT and network communication in daily life is important. However, there is not only a lack of common fabric for integrating IoT with current Internet and but also no emergency call process in the current network communication envi-ronment. To overcome such situations, the prototype of integrating IoT and emergency call process is discussed. A simulated boot-strap platform to provide the discussion of open challenges and solutions for deploying IoT in Internet and the emergency commu-nication system are analyzed by using a service of 3GPP IP multimedia subsystem. Finally, the prototype for supporting WBAN with emergence service is also addressed and the performance results are useful to service providers and network operators that they can estimate their migration to IoT by referring to this experience and experiment results. Furthermore, the queuing model used to achieve the performance of emergency service in IMS and the delay time of the proposed model is analyzed.
文摘The general classification of information systems of remote action, including such system as positioning systems, location systems and remote sensing systems is suggested. In view of formulated limitation conditions the common mathematical information model of data transfer subsystems of considered systems is suggested. The optimization of developed information model is carried out and the optimal operation regimes of these data transfer subsystems are
文摘This paper presents a method for determining the reliability index of a subsystem in the materiel demonstration phase-AHP Failure Rate Method. It fully considers the various factors which influence a subsystem reliability index and solves a difficult problem that puzzles the demonstration personnel.
基金the National Natural Science Foundation of China (60574011)Department of Science and Technology of Liaoning Province (2001401041).
文摘The singularly perturbed bifurcation subsystem is described, and the test conditions of subsystem persistence are deduced. By use of fast and slow reduced subsystem model, the result does not require performing nonlinear transformation. Moreover, it is shown and proved that the persistence of the periodic orbits for Hopf bifurcation in the reduced model through center manifold. Van der Pol oscillator circuit is given to illustrate the persistence of bifurcation subsystems with the full dynamic system.
基金The author would like to thank Fu Qiuhua,Zhang Wei and Fan Qingsong for their surport to this work.
文摘Three groups of cylinder specimens(φ10 mm×10 mm)with 20%,30%and 40%(by mass,the same hereinafter)of ZrO2,were prepared using analytically pure MgO,Al2O3 and ZrO2 powders as the starting materials.The specimens were fired at 1600℃for 5 h,1700℃for 0 h and 1800℃for 7 h,respectively.The microstructure of the MgO-MgAl2O4-ZrO2 subsystem was studied by FESEM.The results show that(1)in the temperature range of 1600-1700℃,solid phase reactions happen in the MgO-MgAl2O4-ZrO2 subsystem,leaving three phases:periclase,spinel and ZrO2(solid dissolving with Mg2+)co-existing;spinellization affects the densification;(2)the specimen with 40%ZrO2 fired at 1800℃has heterogeneous melting microstructure;some areas form typical ternary eutectic MgO-MgAl2O4-ZrO2 with composition of MgO 35.2%-37.2%,Al2O324.2%-26.6%,and ZrO237.2%-39.8%.
文摘The controllability of delay degenerate differential control systems is discussed. Firstly, delay degenerate differential control system was transformed to be canonical form, and the connected terms were gotten rid of, had delay degenerate differential control systems with independent subsystems. For the general delay degenerate differnetial control systems, it was gotten that the necessary and sufficient condition of that they are controllable is that their reachable set is equal to the whole space. For the delay degenerate differential control systems with independent subsystems, it was gotten that the necessary and sufficient conditions of that they are controllable are that their reachable sets are equal to their corresponding subspaces. Then some algebra criteria were gotten. Finally, an example was given to illustrate the main results.
文摘For a Lie triple system T over a field of characteristic zero, some sufficient conditions for T to be two-generated are proved. We also discuss to what extent the two-generated subsystems determine the structure of the system T . One of the main results is that T is solvable if and only if every two elements generates a solvable subsystem. In fact, we give an explicit two-generated law for the two-generated subsystems.
文摘In this paper, the dynamics of rule 106, a Chua’s hyper Bernoulli cellular automata rule, is studied and discussed from the viewpoint of symbolic dynamics. It is presented that rule 106 defines a chaotic subsystem which is topologically mixing and possesses the positive topologically entropy. An effective method of constructing its chaotic subsystems is proposed. Indeed, it is interesting to find that this rule is filled with infinitely many disjoint chaotic subsystems. Special attention is paid to each subsystem on which rule 106 is topologically mixing and possesses the positive topologically entropy. Therefore, it is natural to argue that the intrinsic complexity of rule 106 is high from this viewpoint.
基金National Natural Science Foundation of China(40505019)
文摘In this study,the relationship between the subsystems of Asian summer monsoon is analyzed using U.S.National Centers for Environmental Protection/National Center for Atmospheric Research reanalysis and Climate Prediction Center Merged Analysis of Precipitation monthly mean precipitation data.The results showed that there is significant correlation between the subsystems of Asian summer monsoon.The changes of intensity over the same period show that weak large-scale Asian monsoon,Southeast Asia monsoon and South Asian monsoon are associated with strong East Asian monsoon and decreasing rainfall in related areas.And when the large-scale Asian monsoon is strong,Southeast Asia and South Asia monsoons will be strong and precipitation will increase.While the Southeast Asia monsoon is strong,the South Asia monsoon is weak and the rainfall of South Asia is decreasing,and vice versa.The various subsystems are significantly correlated for all periods of intensity changes.
基金supported from by Unmanned Technology Research Center (UTRC) at Korea Advanced Institute of Science and Technology (KAIST),originally funded by DAPA,ADD
文摘The subsystem synthesis method has been developed in order to improve computational efficiency for a multibody vehicle dynamics model. Using the subsystem synthesis method, equations of motion of the base body and each subsystem can be solved separately. In the subsystem synthesis method, various coordinate systems can be used and various integration methods can be applied in each subsystem, as long as the effective mass matrix and the effective force vector are properly produced. In this paper, comparative study has been carried out for the subsystem synthesis method with Cartesian coordinates and with joint relative coordinates. Two different integration methods such as an explicit integrator and an explicit implicit integrator are employed. In order to see the accuracy and computational efficiency from the different models based on the different coordinate systems and different integration methods, a rough terrain run simulations has been carried out with a 6 × 6 off-road multibody vehicle model.
基金National Science and Technology Major Project of China(No.2019ZX04006001)。
文摘A reliability-growth test is often used to assess complex systems under development.Reliability-growth models are usually used to quantify the achievable reliability indices and predict the expected reliability values.The Crow army-materiel-system-analysis-activity(Crow-AMSAA)projection model and the AMSAA maturity projection(AMPM)-Stein model are suitable for modelling delayed corrective strategies.The AMPM-Stein model,which involves more failure data and requires limited assumptions,is more robust than the Crow-AMSAA projection model.However,the rationality of the Stein factor introduced in the AMPM-Stein model has always been controversial.An AMPM-Stein extended projection model,derived from data regrouping based on similar failure mechanisms,is presented to alleviate the problem.The study demonstrated that the proposed model performed well,the prediction results were credible,and the robustness of the proposed model was examined.Furthermore,the Stein-shrinkage factors,which are derived from components with similar inherent failure mechanisms,are easier to understand and accept in the field of engineering.An example shows that the proposed model is more suitable and accurate than the Crow-AMSAA model and the AMPM-Stein model,by comparing the projection values based on the failure data of the previous phases with the actual values of the current phases.This study provides a technical basis for extensive applications of the proposed model.
文摘The Network Attachment Subsystem (NASS) is introduced to the Next Generation Network (NGN) architecture to enable services independent from access networks and support nomadism for fixed terminals. The NASS is responsible for managing the users attached to the access network in terms of user authentication, allocation of the IP address, and location management. In NGN R1, Telecommunications and Internet Converged Services and Protocols for Advanced Networking (TISPAN) studied the internal architecture and external interface protocols of NASS and published the relevant technical specifications. In NGN R2, TISPAN focuses on the study of mobility and nomadism as well as the ability to support various access network architectures. There still remain several issues that need further study.
文摘The perspective of internal structure of the decision making units (DMUs) was considered as the “black box” when employing data envelopment analysis (DEA) models. However, in the actual world there are always some DMUs that are composed of several sub-units or subsystems, each utilizes the same inputs to generate same outputs. Numerous instances can be listed, such as a firm with a few of plants. In this paper we present models that evaluated the efficiency of DMU which is comprised of same several parallel subsystems, the foremost contribution of our work is that we take the different importance of the subsystems into account in the model, which can be obviously distinguished to the existing DEA model. Secondly, since the alternative optimal multipliers may emerge in the model, the efficiency of each subsystem may be non-unique and we simultaneously develop models of efficiency decomposition for each subsystem. At last a case of technological innovation activities of each province in China is used as an example to state the models.
文摘A two-dimensional Ising square lattice is modeled as a nano-size block array to study by Monte Carlo simulation the magnetic thermal stability of nano-structure magnetic media for data storage, thereon in the blocks J1 > 0 is assigned for the interaction of a pair of nearest-neighbor spins, while 0 J0 J1 for that in regions between the blocks and (J0 + J1)/2 for the nearest-neighbor pairs with one in the block and the other one out of but near-most the block. We show that the magnetic thermal stability of the block accrues with the increase of J1 and with the decrease of J1 - J0 for a given J1, but contrarily, the anchoring ability for the initial magnetic orientation in nano-size block trails off as J1 - J0 diminish. This phenomena and size dependence of such anchoring ability are discussed in detail.