This paper concerns ultimately bounded output-feedback control problems for networked systems with unknown nonlinear dynamics. Sensor-to-observer signal transmission is facilitated over networks that has communication...This paper concerns ultimately bounded output-feedback control problems for networked systems with unknown nonlinear dynamics. Sensor-to-observer signal transmission is facilitated over networks that has communication constraints.These transmissions are carried out over an unreliable communication channel. In order to enhance the utilization rate of measurement data, a buffer-aided strategy is novelly employed to store historical measurements when communication networks are inaccessible. Using the neural network technique, a novel observer-based controller is introduced to address effects of signal transmission behaviors and unknown nonlinear dynamics.Through the application of stochastic analysis and Lyapunov stability, a joint framework is constructed for analyzing resultant system performance under the introduced controller. Subsequently, existence conditions for the desired output-feedback controller are delineated. The required parameters for the observerbased controller are then determined by resolving some specific matrix inequalities. Finally, a simulation example is showcased to confirm method efficacy.展开更多
Different from traditional aggregation method, the unreliable buffers are originally considered and a more general aggregation method is offered, in which not only the unreliable buffers are considered, but also the p...Different from traditional aggregation method, the unreliable buffers are originally considered and a more general aggregation method is offered, in which not only the unreliable buffers are considered, but also the probabilities of system states are obtained by a discrete model rather than the continuous flow model of unreliable manufacturing systems. The solution technique is offered to get the system sate probabilities. The method advances the traditional system aggregation techniques. Numerical results specify the extended aggregation method and also show that the unreliable limited buffers have a strong impact on the efficiency of the production lines.展开更多
This paper mainly investigates the connectivity of the unreliable sensor grid network. We consider an unreliable sensor grid network with mn nodes placed in a certain planar area A, and we assume that each node has in...This paper mainly investigates the connectivity of the unreliable sensor grid network. We consider an unreliable sensor grid network with mn nodes placed in a certain planar area A, and we assume that each node has independent failure probability p and has the same transmission range R. This paper presents a new method for calculating the connectivity probability of the network, which uses thorough mathematical methods to derive the relationship among the network connectivity probability, the probability that a node is ＂failed＂ （not active）, the numbers of node, and the node＇s transmission range in unreliable sensor networks. Our approach is more useful and efficient for given problem and conditions. Such as the numerical calculating results indicate that, for a 100×100 size sensot network, if node failure probability is bounded 0.5%, even if the transmission range is small （such as R = 10）, we can still maintain very high connectivity probability （reach 95.8%）. On the other hand, the simulation results show that building high connectivity probability is entirely possible on unreliable sensor grid networks.展开更多
The work deals with the development of analytical model of multichannel technical queuing system with unreliable servers and input memory where server failure flows and incoming request flows comply with Poissonian la...The work deals with the development of analytical model of multichannel technical queuing system with unreliable servers and input memory where server failure flows and incoming request flows comply with Poissonian laws, while the flows of failed facilities repairs and flows of incoming requests comply with exponential laws of probability distribution. Random process of system change-over is a Markovian process with continuous time and discrete states. Relations binding basic parameters and output characteristics of the system indicated are obtained as probabilities of system staying in the given moment in one of the possible states. The proposed model is the most generalized compared to some models known in literature which could be considered as special cases of the considered model.展开更多
Alice Munro,a famous Canadian Canadian short-story writer.She gained the Nobel Prize for Literature in 2013.Munro’s works focus on women and adolescents.She also writes about the illness and love of the elderly.“The...Alice Munro,a famous Canadian Canadian short-story writer.She gained the Nobel Prize for Literature in 2013.Munro’s works focus on women and adolescents.She also writes about the illness and love of the elderly.“The Bear Came over the Mountain”is one of them.In this story,Munro adopts unreliable narration to depict love between Grant and Fiona.This paper aims to study the love writing and its unreliable narration in this story.Based on the text of love writing,this paper analyzes the specific strategies of unreliable narration.The author believes that the unreliable narration of the love text in the story can be divided into the unreliable narration of character type and information type.Through analysis of these two types of narration in the story,special meaning of unreliable narration to describe love can be found.Besides,Munro’s description also contains her own insight of love:the course of true love does not always run smooth.展开更多
Based on rhetorical research methods of the unreliability,the paper intends to explore the unreliable narrative strategies of the narrator in Grace Paley's The Loudest Voice from the perspectives of the Wayne Boot...Based on rhetorical research methods of the unreliability,the paper intends to explore the unreliable narrative strategies of the narrator in Grace Paley's The Loudest Voice from the perspectives of the Wayne Booth's criterion of the distance between the narrator and the implied author and James Phelan's extension of unreliability on the basis of classical rhetorical narratology,point⁃ing out that the unreliability serves as the narrative trap which is set up to reveal the inner theme of the work:"The loudest voice"-what the protagonist thought she certainly possessed was only her illusion instead of the truth,and Eastern European Jewish com⁃munity was de facto marginalized by the mainstream culture at that time.展开更多
The Tell-Tale Heart is a short story by Edgar Allan Poe. The story is first-person narrative of a narrator who murdered an old man with a clouded eye. This paper aims at identifying the speaker"I"as an unrel...The Tell-Tale Heart is a short story by Edgar Allan Poe. The story is first-person narrative of a narrator who murdered an old man with a clouded eye. This paper aims at identifying the speaker"I"as an unreliable narrator through analyzing the motivation, process and confession of the crime. It is found out that the narrator symbolizes man of evil, while, the old man's vulture eye symbolizes virtue. It's a story about the conflict between evil and virtue.展开更多
As an encyclopedic novel and the summit of Chinese classical literary creation,Hongloumeng has not received due critical attention to its unusual narrative style,let alone abundant unreliable narrative.From unreliable...As an encyclopedic novel and the summit of Chinese classical literary creation,Hongloumeng has not received due critical attention to its unusual narrative style,let alone abundant unreliable narrative.From unreliable narration of narrator and character,this research probes into effective translation strategies to achieve a balance between source text and target text,in light of a comparative analysis of typical illustrations taken from A Dream of Red Mansions and The Story of the Stone.展开更多
Nowadays,high penetration of wind power is integrated into power grids,and WTs usually adopt the MPPT algorithm to maximize power output,which decouples the rotor speeds of wind turbines(WTs)and system frequency.There...Nowadays,high penetration of wind power is integrated into power grids,and WTs usually adopt the MPPT algorithm to maximize power output,which decouples the rotor speeds of wind turbines(WTs)and system frequency.Therefore,WTs cannot provide frequency support like conventional generators.To that end,especially avoiding WTs aggravating excessive power generation during over-frequency events,optimal droop control is proposed to reduce power output by fully utilizing WTs’own potential in accelerating rotors.Due to unreliable communication in a wind farm,a game theory-based distributed rotor kinetic energy optimization model is developed to obtain the ideal WT rotor speed and power reduction.Next,the optimal droop gains for WTs are designed to be proportional to their ideal power reduction.Then,not only the frequency support capability of WTs is fully activated,but also as much wind power as possible will be stored as kinetic energy into the accelerated rotor blades.Finally,the effectiveness and rationality of the proposed control are verified in MATLAB and DIgSILENT.展开更多
In a crumbling tech hub near the marginal coastline,young Angolan developers,despite the challenges of unreliable Internet and dependence on foreign APIs(application programming interfaces),are tapping on donated lapt...In a crumbling tech hub near the marginal coastline,young Angolan developers,despite the challenges of unreliable Internet and dependence on foreign APIs(application programming interfaces),are tapping on donated laptops,debugging health apps that alert rural clinics of disease outbreaks.Their resilience and determination in the face of such obstacles are not just a source of innovation,but also of inspiration and hope.展开更多
This paper considers the discrete-time GeoX/G/1 queueing model with unreliable service station and multiple adaptive delayed vacations from the perspective of reliability research. Following problems will be discussed...This paper considers the discrete-time GeoX/G/1 queueing model with unreliable service station and multiple adaptive delayed vacations from the perspective of reliability research. Following problems will be discussed： 1） The probability that the server is in a ＂generalized busy period＂ at time n; 2） The probability that the service station is in failure at time n, i.e., the transient unavailability of the service station, and the steady state unavailability of the service station; 3） The expected number of service station failures during the time interval （0, hi, and the steady state failure frequency of the service station; 4） The expected number of service station breakdowns in a server＇s ＂generalized busy period＂. Finally, the authors demonstrate that some common discrete-time queueing models with unreliable service station are special cases of the model discussed in this paper.展开更多
When a 3D model is transmitted over a lossy network, some model information may inevitably be missing. Under such situation, one may not be able to visualize the receiving model unless the lost model information has b...When a 3D model is transmitted over a lossy network, some model information may inevitably be missing. Under such situation, one may not be able to visualize the receiving model unless the lost model information has been retransmitted. Progressive model transmission offers an alternative to avoid the ＂all or nothing situation＂ by allowing a model to be visualized with a degraded quality when only part of the model data has been received. Unfortunately, in case some model refinement information is missing, one may still need to wait for such information to be retransmitted before the model can be rendered with a desired visual quality. To address this problem, we have developed a novel error resilient packetization scheme. We first construct a Non-Redundant Directed Acyclic Graph to encode the dependencies among the vertex splits of a progressive mesh. A special Global Graph Equipartition Packing Algorithm is then applied to partitioning this graph into several equal size sub-graphs, which is packed as packets. The packing algorithm comprises two main phases： initial partition phase and global refinement phase. Experimental results demonstrate that the proposed scheme can minimize the dependencies between packets. Hence, it reduces the delay in rendering 3D models with proper quality at the clients.展开更多
This paper deals with a production-inventory system in which there are amachine consisting of multiple unreliable units and a storage facility of fixed capacity. Theproduct produced is stored in the storage facility. ...This paper deals with a production-inventory system in which there are amachine consisting of multiple unreliable units and a storage facility of fixed capacity. Theproduct produced is stored in the storage facility. The demand process for product is acompound Poisson process. We assume that the demand-size distributions are arbitrary,and the unsatisfied demand is backlogged rather than lost. Our main results are to provean existence theorem on stationary distribution of the slack capacity and to derive anexpression of its stationary distribution function.展开更多
To solve the difficulties in allocating buffers for unreliable large production lines, this paper inves-tigated a model combining the genetic algorithm with the discrete event system simulation method. In the simulati...To solve the difficulties in allocating buffers for unreliable large production lines, this paper inves-tigated a model combining the genetic algorithm with the discrete event system simulation method. In the simulation method, times-to-failure of an unreliable large production line is assumed to follow exponential distribution, whereas times-to-repair and times-to-processing are set to follow an Erlang-k distribution. Using a genetic algorithm based on special position-based mapping means and elitist protection strategy, the buffer configuration of an auto-body welding line is optimized. The simulation of the optimized configuration shows that the performance of the production line, such as productivity and the main average utilization of the workstations, is much improved. This model can optimize the allocation of buffers for unreliable large production lines effectively.展开更多
We design online algorithms to schedule unit-length packets with values and deadlines through an unreliable communication channel. In this model, time is discrete. Packets arrive over time; each packet has a non-negat...We design online algorithms to schedule unit-length packets with values and deadlines through an unreliable communication channel. In this model, time is discrete. Packets arrive over time; each packet has a non-negative value and an integer deadline. In each time step, at most one packet can be sent. The ratio of successfully delivering a packet depends on the channel＇s quality of reliability. The objective is to maximize the total value gained by delivering packets no later than their respective deadlines. In this paper, we conduct theoretical and empirical studies of online learning approaches for this model and a few of its variants. These online learning algorithms are analyzed in terms of external regret. We conclude that no online learning algorithms have constant regrets. Our online learning algorithms outperform online competitive algorithms in terms of algorithmic simplicity and running complexity. In general, these online learning algorithms work no worse than the best known competitive online algorithm for maximizing weighted throughput in practice.展开更多
In this paper, we consider the completion time of a job processed on an unreliable machine. Assume that the lifetime and the repair time of the machine and the service time of the job have general distributions. We ob...In this paper, we consider the completion time of a job processed on an unreliable machine. Assume that the lifetime and the repair time of the machine and the service time of the job have general distributions. We obtain the Laplace-Stieltjes transforms and the expectations of the distributions of the completion time, the interruption time and the actual service time. Under some special cases, we derive sufficient and necessary (or sufficient) conditions such that the completion time is larger and smaller than the service time in the sense of the Laplace transform order (or the expectation), respectively展开更多
Cyber-physical systems(CPSs)have emerged as an essential area of research in the last decade,providing a new paradigm for the integration of computational and physical units in modern control systems.Remote state esti...Cyber-physical systems(CPSs)have emerged as an essential area of research in the last decade,providing a new paradigm for the integration of computational and physical units in modern control systems.Remote state estimation(RSE)is an indispensable functional module of CPSs.Recently,it has been demonstrated that malicious agents can manipulate data packets transmitted through unreliable channels of RSE,leading to severe estimation performance degradation.This paper aims to present an overview of recent advances in cyber-attacks and defensive countermeasures,with a specific focus on integrity attacks against RSE.Firstly,two representative frameworks for the synthesis of optimal deception attacks with various performance metrics and stealthiness constraints are discussed,which provide a deeper insight into the vulnerabilities of RSE.Secondly,a detailed review of typical attack detection and resilient estimation algorithms is included,illustrating the latest defensive measures safeguarding RSE from adversaries.Thirdly,some prevalent attacks impairing the confidentiality and data availability of RSE are examined from both attackers'and defenders'perspectives.Finally,several challenges and open problems are presented to inspire further exploration and future research in this field.展开更多
Based on the narrative theory of Shlomith Rimmon-Kenan,the present paper will analyze the close connection between the choice and order of the focalizers and the themes of the novel to show that they are chosen and ar...Based on the narrative theory of Shlomith Rimmon-Kenan,the present paper will analyze the close connection between the choice and order of the focalizers and the themes of the novel to show that they are chosen and arranged deliberately and accorded to its themes.展开更多
Multicollinearity in factor analysis has negative effects, including unreliable factor structure, inconsistent loadings, inflated standard errors, reduced discriminant validity, and difficulties in interpreting factor...Multicollinearity in factor analysis has negative effects, including unreliable factor structure, inconsistent loadings, inflated standard errors, reduced discriminant validity, and difficulties in interpreting factors. It also leads to reduced stability, hindered factor replication, misinterpretation of factor importance, increased parameter estimation instability, reduced power to detect the true factor structure, compromised model fit indices, and biased factor loadings. Multicollinearity introduces uncertainty, complexity, and limited generalizability, hampering factor analysis. To address multicollinearity, researchers can examine the correlation matrix to identify variables with high correlation coefficients. The Variance Inflation Factor (VIF) measures the inflation of regression coefficients due to multicollinearity. Tolerance, the reciprocal of VIF, indicates the proportion of variance in a predictor variable not shared with others. Eigenvalues help assess multicollinearity, with values greater than 1 suggesting the retention of factors. Principal Component Analysis (PCA) reduces dimensionality and identifies highly correlated variables. Other diagnostic measures include the condition number and Cook’s distance. Researchers can center or standardize data, perform variable filtering, use PCA instead of factor analysis, employ factor scores, merge correlated variables, or apply clustering techniques for the solution of the multicollinearity problem. Further research is needed to explore different types of multicollinearity, assess method effectiveness, and investigate the relationship with other factor analysis issues.展开更多
基金supported in part by the National Natural Science Foundation of China (61933007,62273087,U22A2044,61973102,62073180)the Shanghai Pujiang Program of China (22PJ1400400)+1 种基金the Royal Society of the UKthe Alexander von Humboldt Foundation of Germany。
文摘This paper concerns ultimately bounded output-feedback control problems for networked systems with unknown nonlinear dynamics. Sensor-to-observer signal transmission is facilitated over networks that has communication constraints.These transmissions are carried out over an unreliable communication channel. In order to enhance the utilization rate of measurement data, a buffer-aided strategy is novelly employed to store historical measurements when communication networks are inaccessible. Using the neural network technique, a novel observer-based controller is introduced to address effects of signal transmission behaviors and unknown nonlinear dynamics.Through the application of stochastic analysis and Lyapunov stability, a joint framework is constructed for analyzing resultant system performance under the introduced controller. Subsequently, existence conditions for the desired output-feedback controller are delineated. The required parameters for the observerbased controller are then determined by resolving some specific matrix inequalities. Finally, a simulation example is showcased to confirm method efficacy.
基金Great Technology Innovation of Gansu Province,China (No.2GS063-A52-005-01)Natural Science Foundation of Gansu Province,China (No.3ZS062-B25-034)Research Item of Education Department of Gansu Province,China (No.0703-06)
文摘Different from traditional aggregation method, the unreliable buffers are originally considered and a more general aggregation method is offered, in which not only the unreliable buffers are considered, but also the probabilities of system states are obtained by a discrete model rather than the continuous flow model of unreliable manufacturing systems. The solution technique is offered to get the system sate probabilities. The method advances the traditional system aggregation techniques. Numerical results specify the extended aggregation method and also show that the unreliable limited buffers have a strong impact on the efficiency of the production lines.
基金Supported by the National Natural Science Foundation of China(90412012) the Natural Science Foundation of Guangdong Province andthe Post-doctoral Science Foundation of China
文摘This paper mainly investigates the connectivity of the unreliable sensor grid network. We consider an unreliable sensor grid network with mn nodes placed in a certain planar area A, and we assume that each node has independent failure probability p and has the same transmission range R. This paper presents a new method for calculating the connectivity probability of the network, which uses thorough mathematical methods to derive the relationship among the network connectivity probability, the probability that a node is ＂failed＂ （not active）, the numbers of node, and the node＇s transmission range in unreliable sensor networks. Our approach is more useful and efficient for given problem and conditions. Such as the numerical calculating results indicate that, for a 100×100 size sensot network, if node failure probability is bounded 0.5%, even if the transmission range is small （such as R = 10）, we can still maintain very high connectivity probability （reach 95.8%）. On the other hand, the simulation results show that building high connectivity probability is entirely possible on unreliable sensor grid networks.
文摘The work deals with the development of analytical model of multichannel technical queuing system with unreliable servers and input memory where server failure flows and incoming request flows comply with Poissonian laws, while the flows of failed facilities repairs and flows of incoming requests comply with exponential laws of probability distribution. Random process of system change-over is a Markovian process with continuous time and discrete states. Relations binding basic parameters and output characteristics of the system indicated are obtained as probabilities of system staying in the given moment in one of the possible states. The proposed model is the most generalized compared to some models known in literature which could be considered as special cases of the considered model.
文摘Alice Munro,a famous Canadian Canadian short-story writer.She gained the Nobel Prize for Literature in 2013.Munro’s works focus on women and adolescents.She also writes about the illness and love of the elderly.“The Bear Came over the Mountain”is one of them.In this story,Munro adopts unreliable narration to depict love between Grant and Fiona.This paper aims to study the love writing and its unreliable narration in this story.Based on the text of love writing,this paper analyzes the specific strategies of unreliable narration.The author believes that the unreliable narration of the love text in the story can be divided into the unreliable narration of character type and information type.Through analysis of these two types of narration in the story,special meaning of unreliable narration to describe love can be found.Besides,Munro’s description also contains her own insight of love:the course of true love does not always run smooth.
文摘Based on rhetorical research methods of the unreliability,the paper intends to explore the unreliable narrative strategies of the narrator in Grace Paley's The Loudest Voice from the perspectives of the Wayne Booth's criterion of the distance between the narrator and the implied author and James Phelan's extension of unreliability on the basis of classical rhetorical narratology,point⁃ing out that the unreliability serves as the narrative trap which is set up to reveal the inner theme of the work:"The loudest voice"-what the protagonist thought she certainly possessed was only her illusion instead of the truth,and Eastern European Jewish com⁃munity was de facto marginalized by the mainstream culture at that time.
文摘The Tell-Tale Heart is a short story by Edgar Allan Poe. The story is first-person narrative of a narrator who murdered an old man with a clouded eye. This paper aims at identifying the speaker"I"as an unreliable narrator through analyzing the motivation, process and confession of the crime. It is found out that the narrator symbolizes man of evil, while, the old man's vulture eye symbolizes virtue. It's a story about the conflict between evil and virtue.
文摘As an encyclopedic novel and the summit of Chinese classical literary creation,Hongloumeng has not received due critical attention to its unusual narrative style,let alone abundant unreliable narrative.From unreliable narration of narrator and character,this research probes into effective translation strategies to achieve a balance between source text and target text,in light of a comparative analysis of typical illustrations taken from A Dream of Red Mansions and The Story of the Stone.
基金supported by National Key R&D Program of China(Basic Research Class)(No.2017YFB0903000)National Natural Science Foundation of China(No.U1909201)。
文摘Nowadays,high penetration of wind power is integrated into power grids,and WTs usually adopt the MPPT algorithm to maximize power output,which decouples the rotor speeds of wind turbines(WTs)and system frequency.Therefore,WTs cannot provide frequency support like conventional generators.To that end,especially avoiding WTs aggravating excessive power generation during over-frequency events,optimal droop control is proposed to reduce power output by fully utilizing WTs’own potential in accelerating rotors.Due to unreliable communication in a wind farm,a game theory-based distributed rotor kinetic energy optimization model is developed to obtain the ideal WT rotor speed and power reduction.Next,the optimal droop gains for WTs are designed to be proportional to their ideal power reduction.Then,not only the frequency support capability of WTs is fully activated,but also as much wind power as possible will be stored as kinetic energy into the accelerated rotor blades.Finally,the effectiveness and rationality of the proposed control are verified in MATLAB and DIgSILENT.
文摘In a crumbling tech hub near the marginal coastline,young Angolan developers,despite the challenges of unreliable Internet and dependence on foreign APIs(application programming interfaces),are tapping on donated laptops,debugging health apps that alert rural clinics of disease outbreaks.Their resilience and determination in the face of such obstacles are not just a source of innovation,but also of inspiration and hope.
基金supported in part by the National Natural Science Foundation of China under Grant Nos. 71171138,70871084the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No.200806360001
文摘This paper considers the discrete-time GeoX/G/1 queueing model with unreliable service station and multiple adaptive delayed vacations from the perspective of reliability research. Following problems will be discussed： 1） The probability that the server is in a ＂generalized busy period＂ at time n; 2） The probability that the service station is in failure at time n, i.e., the transient unavailability of the service station, and the steady state unavailability of the service station; 3） The expected number of service station failures during the time interval （0, hi, and the steady state failure frequency of the service station; 4） The expected number of service station breakdowns in a server＇s ＂generalized busy period＂. Finally, the authors demonstrate that some common discrete-time queueing models with unreliable service station are special cases of the model discussed in this paper.
基金Supported by the National Natural Science Foundation of China under Grant No. 60533080the National Research Foundation for Doctoral Program of Higher Education of China Under Grant No. 20060335111.
文摘When a 3D model is transmitted over a lossy network, some model information may inevitably be missing. Under such situation, one may not be able to visualize the receiving model unless the lost model information has been retransmitted. Progressive model transmission offers an alternative to avoid the ＂all or nothing situation＂ by allowing a model to be visualized with a degraded quality when only part of the model data has been received. Unfortunately, in case some model refinement information is missing, one may still need to wait for such information to be retransmitted before the model can be rendered with a desired visual quality. To address this problem, we have developed a novel error resilient packetization scheme. We first construct a Non-Redundant Directed Acyclic Graph to encode the dependencies among the vertex splits of a progressive mesh. A special Global Graph Equipartition Packing Algorithm is then applied to partitioning this graph into several equal size sub-graphs, which is packed as packets. The packing algorithm comprises two main phases： initial partition phase and global refinement phase. Experimental results demonstrate that the proposed scheme can minimize the dependencies between packets. Hence, it reduces the delay in rendering 3D models with proper quality at the clients.
文摘This paper deals with a production-inventory system in which there are amachine consisting of multiple unreliable units and a storage facility of fixed capacity. Theproduct produced is stored in the storage facility. The demand process for product is acompound Poisson process. We assume that the demand-size distributions are arbitrary,and the unsatisfied demand is backlogged rather than lost. Our main results are to provean existence theorem on stationary distribution of the slack capacity and to derive anexpression of its stationary distribution function.
基金Supported by the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of the Ministry of Education China the National High-Tech Research and Development (863) Program of China (No. 2001AA411140)
文摘To solve the difficulties in allocating buffers for unreliable large production lines, this paper inves-tigated a model combining the genetic algorithm with the discrete event system simulation method. In the simulation method, times-to-failure of an unreliable large production line is assumed to follow exponential distribution, whereas times-to-repair and times-to-processing are set to follow an Erlang-k distribution. Using a genetic algorithm based on special position-based mapping means and elitist protection strategy, the buffer configuration of an auto-body welding line is optimized. The simulation of the optimized configuration shows that the performance of the production line, such as productivity and the main average utilization of the workstations, is much improved. This model can optimize the allocation of buffers for unreliable large production lines effectively.
基金Supported by US National Science Foundation (Nos. CCF-0915681 and CCF-1146578)DARPA’s Mission-Resilient Clouds Program under Contract 1FA8650-11-C-7190
文摘We design online algorithms to schedule unit-length packets with values and deadlines through an unreliable communication channel. In this model, time is discrete. Packets arrive over time; each packet has a non-negative value and an integer deadline. In each time step, at most one packet can be sent. The ratio of successfully delivering a packet depends on the channel＇s quality of reliability. The objective is to maximize the total value gained by delivering packets no later than their respective deadlines. In this paper, we conduct theoretical and empirical studies of online learning approaches for this model and a few of its variants. These online learning algorithms are analyzed in terms of external regret. We conclude that no online learning algorithms have constant regrets. Our online learning algorithms outperform online competitive algorithms in terms of algorithmic simplicity and running complexity. In general, these online learning algorithms work no worse than the best known competitive online algorithm for maximizing weighted throughput in practice.
基金the National Key Project of China (No.970211017) and the NationalNatural Sciences Foundation of China (No.69674013).
文摘In this paper, we consider the completion time of a job processed on an unreliable machine. Assume that the lifetime and the repair time of the machine and the service time of the job have general distributions. We obtain the Laplace-Stieltjes transforms and the expectations of the distributions of the completion time, the interruption time and the actual service time. Under some special cases, we derive sufficient and necessary (or sufficient) conditions such that the completion time is larger and smaller than the service time in the sense of the Laplace transform order (or the expectation), respectively
基金the Natural Sciences and Engineering Research Council(NSERC)of Canada。
文摘Cyber-physical systems(CPSs)have emerged as an essential area of research in the last decade,providing a new paradigm for the integration of computational and physical units in modern control systems.Remote state estimation(RSE)is an indispensable functional module of CPSs.Recently,it has been demonstrated that malicious agents can manipulate data packets transmitted through unreliable channels of RSE,leading to severe estimation performance degradation.This paper aims to present an overview of recent advances in cyber-attacks and defensive countermeasures,with a specific focus on integrity attacks against RSE.Firstly,two representative frameworks for the synthesis of optimal deception attacks with various performance metrics and stealthiness constraints are discussed,which provide a deeper insight into the vulnerabilities of RSE.Secondly,a detailed review of typical attack detection and resilient estimation algorithms is included,illustrating the latest defensive measures safeguarding RSE from adversaries.Thirdly,some prevalent attacks impairing the confidentiality and data availability of RSE are examined from both attackers'and defenders'perspectives.Finally,several challenges and open problems are presented to inspire further exploration and future research in this field.
文摘Based on the narrative theory of Shlomith Rimmon-Kenan,the present paper will analyze the close connection between the choice and order of the focalizers and the themes of the novel to show that they are chosen and arranged deliberately and accorded to its themes.
文摘Multicollinearity in factor analysis has negative effects, including unreliable factor structure, inconsistent loadings, inflated standard errors, reduced discriminant validity, and difficulties in interpreting factors. It also leads to reduced stability, hindered factor replication, misinterpretation of factor importance, increased parameter estimation instability, reduced power to detect the true factor structure, compromised model fit indices, and biased factor loadings. Multicollinearity introduces uncertainty, complexity, and limited generalizability, hampering factor analysis. To address multicollinearity, researchers can examine the correlation matrix to identify variables with high correlation coefficients. The Variance Inflation Factor (VIF) measures the inflation of regression coefficients due to multicollinearity. Tolerance, the reciprocal of VIF, indicates the proportion of variance in a predictor variable not shared with others. Eigenvalues help assess multicollinearity, with values greater than 1 suggesting the retention of factors. Principal Component Analysis (PCA) reduces dimensionality and identifies highly correlated variables. Other diagnostic measures include the condition number and Cook’s distance. Researchers can center or standardize data, perform variable filtering, use PCA instead of factor analysis, employ factor scores, merge correlated variables, or apply clustering techniques for the solution of the multicollinearity problem. Further research is needed to explore different types of multicollinearity, assess method effectiveness, and investigate the relationship with other factor analysis issues.
