In this paper, we study the supervisory control problem of discrete event systems assuming that cyber-attacks might occur. In particular, we focus on the problem of liveness enforcement and consider a sensor-reading m...In this paper, we study the supervisory control problem of discrete event systems assuming that cyber-attacks might occur. In particular, we focus on the problem of liveness enforcement and consider a sensor-reading modification attack(SM-attack) that may disguise the occurrence of an event as that of another event by intruding sensor communication channels. To solve the problem, we introduce non-deterministic supervisors in the paper, which associate to every observed sequence a set of possible control actions offline and choose a control action from the set randomly online to control the system. Specifically, given a bounded Petri net(PN) as the reference formalism and an SMattack, an algorithm that synthesizes a liveness-enforcing nondeterministic supervisor tolerant to the SM-attack is proposed for the first time.展开更多
为降低中点箝位型(neutral point clamped,NPC)三电平整流器的电流谐波,在dq同步旋转坐标系下推导出带中点电压耦合项的NPC三电平整流器数学模型,并分析中点电压对电流控制的影响。对模型中的中点电压耦合项和交流侧等效电阻会增大电流...为降低中点箝位型(neutral point clamped,NPC)三电平整流器的电流谐波,在dq同步旋转坐标系下推导出带中点电压耦合项的NPC三电平整流器数学模型,并分析中点电压对电流控制的影响。对模型中的中点电压耦合项和交流侧等效电阻会增大电流谐波及无法通过常规方法进行准确估计的问题,设计一种混合参数自适应的迭代学习控制方法,以进行解耦控制并消除不确定参数的影响。通过构造Lyapunov函数和理论推导验证控制方法的稳定性。在整流器硬件平台上进行试验验证,结果表明,所设计的控制方法可有效降低电流谐波。展开更多
为进一步提高中点电压钳制(neutral point clamped,NPC)H桥级联五电平逆变器的动态响应、降低控制器计算负担的同时确保装置低损耗运行,文中在电压矢量矩形区域分类的基础上,提出一种以满足动态响应和降低开关损耗为目标的两级优化模型...为进一步提高中点电压钳制(neutral point clamped,NPC)H桥级联五电平逆变器的动态响应、降低控制器计算负担的同时确保装置低损耗运行,文中在电压矢量矩形区域分类的基础上,提出一种以满足动态响应和降低开关损耗为目标的两级优化模型预测电压控制策略。首先根据逆变器数学模型和期望电流进行目标电压矢量计算、修正,接着基于矩形区域分类对目标电压矢量进行定位;并以定位后的候选矢量为基础,设计了两级优化目标函数以输出满足要求的最优矢量。仿真和实验结果验证了该方法的有效性,与空间矢量脉宽调制以及传统模型预测电流、电压控制策略相比,该文所研究的两级优化模型预测电压控制策略,在确保逆变器动态响应的前提下既能降低控制器计算负担,还能有效减少器件开关损耗。展开更多
The supervisory control problem for discrete event system(DES) under control involves identifying the supervisor, if one exists, which, when synchronously composed with the DES,results in a system that conforms to the...The supervisory control problem for discrete event system(DES) under control involves identifying the supervisor, if one exists, which, when synchronously composed with the DES,results in a system that conforms to the control specification. In this context, we consider a non-deterministic DES under complete observation and control specification expressed in action-based propositional μ-calculus. The key to our solution is the process of quotienting the control specification against the plan resulting in a new μ-calculus formula such that a model for the formula is the supervisor. Thus the task of control synthesis is reduced a problem of μ-calculus satisfiability. In contrast to the existing μ-calculus quotienting-based techniques that are developed in deterministic setting, our quotienting rules can handle nondeterminism in the plant models. Another distinguishing feature of our technique is that while existing techniques use a separate μ-calculus formula to describe the controllability constraint(that uncontrollable events of plants are never disabled by a supervisor), we absorb this constraint as part of quotienting which allows us to directly capture more general state-dependent controllability constraints. Finally, we develop a tableau-based technique for verifying satisfiability of quotiented formula and model generation. The runtime for the technique is exponential in terms of the size of the plan and the control specification. A better complexity result that is polynomial to plant size and exponential to specification size is obtained when the controllability property is state-independent. A prototype implementation in a tabled logic programming language as well as some experimental results are presented.展开更多
Watson Crick automata are finite automata working on double strands. Extensive research work has already been done on non deterministic Watson Crick automata and on deterministic Watson Crick automata. Parallel Commun...Watson Crick automata are finite automata working on double strands. Extensive research work has already been done on non deterministic Watson Crick automata and on deterministic Watson Crick automata. Parallel Communicating Watson Crick automata systems have been introduced by E. Czeziler et al. In this paper we discuss about a variant of Watson Crick automata known as the two-way Watson Crick automata which are more powerful than non-deterministic Watson Crick automata. We also establish the equivalence of different subclasses of two-way Watson crick automata. We further show that recursively enumerable (RE) languages can be realized by an image of generalized sequential machine (gsm) mapping of two-way Watson-Crick automata.展开更多
Modeling and forecasting of the groundwater water table are a major component of effective planning and management of water resources. One way to predict the groundwater level is analysis using a non-deterministic mod...Modeling and forecasting of the groundwater water table are a major component of effective planning and management of water resources. One way to predict the groundwater level is analysis using a non-deterministic model. This study assessed the performance of such models in predicting the groundwater level at Kashan aquifer. Data from 36 piezometer wells in Kashan aquifer for 1999 to 2010 were used. The desired statistical interval was divided into two parts and statistics for 1990 to 2004 were used for modeling and statistics from 2005 to 2010 were used for valediction of the model. The Akaike criterion and correlation coefficients were used to determine the accuracy of the prediction models. The results indicated that the AR(2) model more accurately predicted ground water level in the plains;using this model, the groundwater water table was predicted for up to 60 mo.展开更多
随着新能源和微电网的高速发展,孤岛状态下逆变器的故障穿越能力显得尤为重要。针对现有控制方法下孤岛中点钳位(neutral point clamped,NPC)逆变器故障穿越能力弱的问题,提出基于模型预测控制的孤岛微电网NPC逆变器故障穿越控制方法。...随着新能源和微电网的高速发展,孤岛状态下逆变器的故障穿越能力显得尤为重要。针对现有控制方法下孤岛中点钳位(neutral point clamped,NPC)逆变器故障穿越能力弱的问题,提出基于模型预测控制的孤岛微电网NPC逆变器故障穿越控制方法。通过比较负载电压与参考电压实现故障高速诊断;通过提高故障相参考电流幅值提升故障相电流;通过划定计算扇区、消除冗余计算减少计算量和避免权重系数设计;为保证电能质量以及减小数据测量和算法计算产生的延时,采用两步预测方法对延时进行补偿。在Matlab/Simulink中搭建三相LCL孤岛NPC逆变器仿真模型,仿真结果表明,该控制方法在孤岛微电网正常运行时能够将三相电流THD均值控制在2%以内,发生故障时,对故障相电流THD值控制在4%以内,对非故障相电流THD值控制在1.5%以内,能够有效提升孤岛NPC逆变器的故障穿越能力。展开更多
Castor,scientifically known as Ricinus communis L.,is among the top ten oil crops globally.It is considered a renewable resource and is commonly referred to as‘green oil’.Castor seeds contain castor oil as their mai...Castor,scientifically known as Ricinus communis L.,is among the top ten oil crops globally.It is considered a renewable resource and is commonly referred to as‘green oil’.Castor seeds contain castor oil as their main component,which is predominantly composed of ricinoleic acid.This study utilized RNAi technology to silence the NPC6 gene in NO.2129 castor,resulting in the creation of mutant plants L1 and L2.The weight of 100 dry seed kernels from L1 and L2 exceeds that from NO.2129.The crude fat and ricinoleic acid levels of L1 and L2 were higher than those of NO.2129 at various developmental stages.In the proteomics analysis of 60-day-old castor seeds,a total of 21 differentially expressed proteins were identified,out of which 19 were successfully recognized.Eleven of the differentially expressed proteins identified were legumins,which play a crucial role in nutrient storage within the seed.Silencing the NPC6 gene results in the accumulation of ricinoleic acid in castor seeds.The findings of this study not only enhance our knowledge of NPC6’s role in regulating castor seed oil synthesis but also offer fresh perspectives for investigating oil synthesis and accumulation in other plant species.展开更多
The recently experienced hype concerning the so-called “4<sup>th</sup> Industrial Revolution” of production systems has prompted several papers of various subtopics regarding Cyber-Phdysical Production S...The recently experienced hype concerning the so-called “4<sup>th</sup> Industrial Revolution” of production systems has prompted several papers of various subtopics regarding Cyber-Phdysical Production Systems (CPPS). However, important aspects such as the modelling of CPPS to understand the theory regarding the performance of highly non-ergodic and non-deterministic flexible manufacturing systems in terms of Exit Rate (ER), Manufacturing Lead Time (MLT), and On-Time Delivery (OTD) have not yet been examined systematically and even less modeled analytically. To develop the topic, in this paper, the prerequisites for modelling such systems are defined in order to be able to derive an explicit and dedicated production mathematics-based understanding of CPPS and its dynamics: switching from explorative simulation to rational modelling of the manufacturing “physics” led to an own and specific manufacturing theory. The findings have led to enouncing, among others, the Theorem of Non-Ergodicity as well as the Batch Cycle Time Deviation Function giving important insights to model digital twin-based CPPS for complying with the mandatory OTD.展开更多
基金supported in part by the Public Technology Research Plan of Zhejiang Province (LGJ21F030001)the National Natural Science Foundation of China (62302448)the Zhejiang Provincial Key Laboratory of New Network Standards and Technologies (2013E10012)。
文摘In this paper, we study the supervisory control problem of discrete event systems assuming that cyber-attacks might occur. In particular, we focus on the problem of liveness enforcement and consider a sensor-reading modification attack(SM-attack) that may disguise the occurrence of an event as that of another event by intruding sensor communication channels. To solve the problem, we introduce non-deterministic supervisors in the paper, which associate to every observed sequence a set of possible control actions offline and choose a control action from the set randomly online to control the system. Specifically, given a bounded Petri net(PN) as the reference formalism and an SMattack, an algorithm that synthesizes a liveness-enforcing nondeterministic supervisor tolerant to the SM-attack is proposed for the first time.
文摘为降低中点箝位型(neutral point clamped,NPC)三电平整流器的电流谐波,在dq同步旋转坐标系下推导出带中点电压耦合项的NPC三电平整流器数学模型,并分析中点电压对电流控制的影响。对模型中的中点电压耦合项和交流侧等效电阻会增大电流谐波及无法通过常规方法进行准确估计的问题,设计一种混合参数自适应的迭代学习控制方法,以进行解耦控制并消除不确定参数的影响。通过构造Lyapunov函数和理论推导验证控制方法的稳定性。在整流器硬件平台上进行试验验证,结果表明,所设计的控制方法可有效降低电流谐波。
文摘虚拟同步机VSG(virtual synchronous generator)通过模拟同步机特性为新能源并网提供惯性和阻尼。然而,电力电子开关器件高频开关过程中可能会发生断路故障,导致输出电流波形严重畸变,影响电网安全稳定运行。针对中点箝位型NPC(neutral point clamped)三电平VSG桥臂故障问题,提出一种中点电压均衡的VSG容错模型预测控制策略。分析NPC三电平VSG单相桥臂故障后运行机理,在开关器件故障后利用直流侧电容组成虚拟桥臂,重构为VSG桥臂故障容错结构。建立故障情况下预测电流模型,重构故障状态空间电压矢量,将直流侧中点电容电压引入容错模型代价函数,减小电容电压波动,实现VSG桥臂故障容错运行。实验结果表明,在开关器件发生故障后,NPC三电平VSG能容错连续运行,验证了所提模型预测容错控制策略的有效性,提高了VSG运行可靠性。
文摘为进一步提高中点电压钳制(neutral point clamped,NPC)H桥级联五电平逆变器的动态响应、降低控制器计算负担的同时确保装置低损耗运行,文中在电压矢量矩形区域分类的基础上,提出一种以满足动态响应和降低开关损耗为目标的两级优化模型预测电压控制策略。首先根据逆变器数学模型和期望电流进行目标电压矢量计算、修正,接着基于矩形区域分类对目标电压矢量进行定位;并以定位后的候选矢量为基础,设计了两级优化目标函数以输出满足要求的最优矢量。仿真和实验结果验证了该方法的有效性,与空间矢量脉宽调制以及传统模型预测电流、电压控制策略相比,该文所研究的两级优化模型预测电压控制策略,在确保逆变器动态响应的前提下既能降低控制器计算负担,还能有效减少器件开关损耗。
基金supported in part by the National Sci-ence Foundation (NSF-ECCS-1509420, NSF-CSSI-2004766)。
文摘The supervisory control problem for discrete event system(DES) under control involves identifying the supervisor, if one exists, which, when synchronously composed with the DES,results in a system that conforms to the control specification. In this context, we consider a non-deterministic DES under complete observation and control specification expressed in action-based propositional μ-calculus. The key to our solution is the process of quotienting the control specification against the plan resulting in a new μ-calculus formula such that a model for the formula is the supervisor. Thus the task of control synthesis is reduced a problem of μ-calculus satisfiability. In contrast to the existing μ-calculus quotienting-based techniques that are developed in deterministic setting, our quotienting rules can handle nondeterminism in the plant models. Another distinguishing feature of our technique is that while existing techniques use a separate μ-calculus formula to describe the controllability constraint(that uncontrollable events of plants are never disabled by a supervisor), we absorb this constraint as part of quotienting which allows us to directly capture more general state-dependent controllability constraints. Finally, we develop a tableau-based technique for verifying satisfiability of quotiented formula and model generation. The runtime for the technique is exponential in terms of the size of the plan and the control specification. A better complexity result that is polynomial to plant size and exponential to specification size is obtained when the controllability property is state-independent. A prototype implementation in a tabled logic programming language as well as some experimental results are presented.
文摘Watson Crick automata are finite automata working on double strands. Extensive research work has already been done on non deterministic Watson Crick automata and on deterministic Watson Crick automata. Parallel Communicating Watson Crick automata systems have been introduced by E. Czeziler et al. In this paper we discuss about a variant of Watson Crick automata known as the two-way Watson Crick automata which are more powerful than non-deterministic Watson Crick automata. We also establish the equivalence of different subclasses of two-way Watson crick automata. We further show that recursively enumerable (RE) languages can be realized by an image of generalized sequential machine (gsm) mapping of two-way Watson-Crick automata.
文摘Modeling and forecasting of the groundwater water table are a major component of effective planning and management of water resources. One way to predict the groundwater level is analysis using a non-deterministic model. This study assessed the performance of such models in predicting the groundwater level at Kashan aquifer. Data from 36 piezometer wells in Kashan aquifer for 1999 to 2010 were used. The desired statistical interval was divided into two parts and statistics for 1990 to 2004 were used for modeling and statistics from 2005 to 2010 were used for valediction of the model. The Akaike criterion and correlation coefficients were used to determine the accuracy of the prediction models. The results indicated that the AR(2) model more accurately predicted ground water level in the plains;using this model, the groundwater water table was predicted for up to 60 mo.
文摘随着新能源和微电网的高速发展,孤岛状态下逆变器的故障穿越能力显得尤为重要。针对现有控制方法下孤岛中点钳位(neutral point clamped,NPC)逆变器故障穿越能力弱的问题,提出基于模型预测控制的孤岛微电网NPC逆变器故障穿越控制方法。通过比较负载电压与参考电压实现故障高速诊断;通过提高故障相参考电流幅值提升故障相电流;通过划定计算扇区、消除冗余计算减少计算量和避免权重系数设计;为保证电能质量以及减小数据测量和算法计算产生的延时,采用两步预测方法对延时进行补偿。在Matlab/Simulink中搭建三相LCL孤岛NPC逆变器仿真模型,仿真结果表明,该控制方法在孤岛微电网正常运行时能够将三相电流THD均值控制在2%以内,发生故障时,对故障相电流THD值控制在4%以内,对非故障相电流THD值控制在1.5%以内,能够有效提升孤岛NPC逆变器的故障穿越能力。
基金supported by the following agencies:Natural Science Foundation of Jilin Province (YDZJ202201ZYTS453)Scientific Research Project of the Jilin Provincial Department of Education (JJKH20220010KJ)+6 种基金supported by Program for Innovative Research Team of Baicheng Normal University,National Natural Science Foundation of China (31860071)Inner Mongolia Autonomous Region Natural Science Foundation Project (2021MS03008)Inner Mongolia Autonomous Region Grassland Talent Innovation Team (2022)2022 Basic Scientific Research Business Cost Project of Universities Directly under the Autonomous Region (237)Open Fund Project of Inner Mongolia Castor Industry Collaborative Innovation Center (MDK2021011,MDK2022014,MDK2022008,MDK2021008,MDK2022009)Fundamental Research Funds for Universities Directly under the Autonomous Region in 2023 of Inner Mongolia University for Nationalities (225,227,243,244)New Agricultural Science Research and Reform Practice Project of the Ministry of Education (2020114)。
文摘Castor,scientifically known as Ricinus communis L.,is among the top ten oil crops globally.It is considered a renewable resource and is commonly referred to as‘green oil’.Castor seeds contain castor oil as their main component,which is predominantly composed of ricinoleic acid.This study utilized RNAi technology to silence the NPC6 gene in NO.2129 castor,resulting in the creation of mutant plants L1 and L2.The weight of 100 dry seed kernels from L1 and L2 exceeds that from NO.2129.The crude fat and ricinoleic acid levels of L1 and L2 were higher than those of NO.2129 at various developmental stages.In the proteomics analysis of 60-day-old castor seeds,a total of 21 differentially expressed proteins were identified,out of which 19 were successfully recognized.Eleven of the differentially expressed proteins identified were legumins,which play a crucial role in nutrient storage within the seed.Silencing the NPC6 gene results in the accumulation of ricinoleic acid in castor seeds.The findings of this study not only enhance our knowledge of NPC6’s role in regulating castor seed oil synthesis but also offer fresh perspectives for investigating oil synthesis and accumulation in other plant species.
文摘The recently experienced hype concerning the so-called “4<sup>th</sup> Industrial Revolution” of production systems has prompted several papers of various subtopics regarding Cyber-Phdysical Production Systems (CPPS). However, important aspects such as the modelling of CPPS to understand the theory regarding the performance of highly non-ergodic and non-deterministic flexible manufacturing systems in terms of Exit Rate (ER), Manufacturing Lead Time (MLT), and On-Time Delivery (OTD) have not yet been examined systematically and even less modeled analytically. To develop the topic, in this paper, the prerequisites for modelling such systems are defined in order to be able to derive an explicit and dedicated production mathematics-based understanding of CPPS and its dynamics: switching from explorative simulation to rational modelling of the manufacturing “physics” led to an own and specific manufacturing theory. The findings have led to enouncing, among others, the Theorem of Non-Ergodicity as well as the Batch Cycle Time Deviation Function giving important insights to model digital twin-based CPPS for complying with the mandatory OTD.