This paper discusses some issues on human reliability model of time dependent human behavior. Some results of the crew reliability experiment on Tsinghua training simulator in China are given, Meanwhile, a case of ca...This paper discusses some issues on human reliability model of time dependent human behavior. Some results of the crew reliability experiment on Tsinghua training simulator in China are given, Meanwhile, a case of calculation for human error probability during anticipated transient without scram (ATWS) based on the data drew from the recent experiment is offered.展开更多
Taken discourse production as the research objective,it holds that discourse production is dynamic in human communication.It attempts to analyze the dynamics on the basis of Relevance-adaption model from the perspecti...Taken discourse production as the research objective,it holds that discourse production is dynamic in human communication.It attempts to analyze the dynamics on the basis of Relevance-adaption model from the perspective of cognitive pragmatics and explain the role of the context dynamics that plays in the discourse production.展开更多
如何提高动作技能习得效率是动作学习与控制(Motor Learning and Control)领域的重点课题。已有研究肯定了触觉学习的有益性,但干预方案缺乏稳定性或练习内容简单,为此研制了一种新型体育器材来创建有效的触觉学习条件,然后开展为期2周...如何提高动作技能习得效率是动作学习与控制(Motor Learning and Control)领域的重点课题。已有研究肯定了触觉学习的有益性,但干预方案缺乏稳定性或练习内容简单,为此研制了一种新型体育器材来创建有效的触觉学习条件,然后开展为期2周、每周4次的实验干预,发现:在缺乏动作概念指导的情况下触觉学习产生的习得效率较低,而一旦练习者建立了动作概念,触觉学习明显产生了比认知学习更高的习得效率,而且认知学习有利于初学者掌握复杂动作技能,触觉学习有利于掌握简单动作技能,所以建议初学者采用“概念打底,触觉推进”的动作技能学习策略。展开更多
English language learners' pragmatic competence is related to their success incross-cultural communication. Cognitive approaches, mainly the Noticing Hypothesis and Analysis/Control Model, have provided some insig...English language learners' pragmatic competence is related to their success incross-cultural communication. Cognitive approaches, mainly the Noticing Hypothesis and Analysis/Control Model, have provided some insights into the question of how to effectively develop second language(L2) learners' pragmatic competence. Empirical studies based on cognitive theoretical constructs suggest that pragmatic activitiesthat draw learners' attention and help them control attention to relevant and appropriate information and integrate those forms in real time of communication contribute to the development of interlanguage pragmatic competence.展开更多
Two pieces of news reports on Yangtze Sunken Ship event are analyzed in this essay to prove the influence of context model in news reports discourse by comparative analysis approach. Through illustrating the different...Two pieces of news reports on Yangtze Sunken Ship event are analyzed in this essay to prove the influence of context model in news reports discourse by comparative analysis approach. Through illustrating the different expressions in these reports discourse, the process how cognition(or context model) influences and determines the production and understanding of discourse has been demonstrated.展开更多
We study cooperative spectrum sensing in cognitive radio (CR) networks using the hidden Markov model (HMM) for opportunistic spectrum access (OSA). We assume that the primary channel operates in a time division multip...We study cooperative spectrum sensing in cognitive radio (CR) networks using the hidden Markov model (HMM) for opportunistic spectrum access (OSA). We assume that the primary channel operates in a time division multiple address (TDMA) manner. Thus, spectrum sensing is operating in a slot-by-slot basis. In contrast to the conventional Bayesian updating using only one observation, in this work, we propose to perform the update in a concatenated fashion with all the observations available from the secondary users (SUs). In the proposed scheme, a predefined threshold on the belief is used for determining the channel activity. With the threshold, the proposed scheme is more flexible in the system operation than the simple majority vote scheme, in which no such threshold is available. We compare, by simulations, the performance of the proposed concatenated update scheme with that of the majority vote scheme and show that the probabilities of correctly detecting a busy state and an idle state are about 1 as the number of SUs is as large as 15, so the effects of the further increase in the number of SUs are limited.展开更多
A cognitive radio（CR） network with energy harvesting（EH） is considered to improve both spectrum efficiency and energy efficiency. A hidden Markov model（HMM） is used to characterize the imperfect spectrum sensing...A cognitive radio（CR） network with energy harvesting（EH） is considered to improve both spectrum efficiency and energy efficiency. A hidden Markov model（HMM） is used to characterize the imperfect spectrum sensing process. In order to maximize the whole satisfaction degree（WSD） of the cognitive radio network, a tradeoff between the average throughput of the secondary user（SU） and the interference to the primary user（PU） is analyzed. We formulate the satisfaction degree optimization problem as a mixed integer nonlinear programming（MINLP） problem. The satisfaction degree optimization problem is solved by using differential evolution（DE） algorithm. The proposed optimization problem allows the network to adaptively achieve the optimal solution based on its required quality of service（Qos）. Numerical results are given to verify our analysis.展开更多
Dynamic spectrum access policy is crucial in improving the performance of over- lay cognitive radio networks. Most of the previ- ous works on spectrum sensing and dynamic spe- ctrum access consider the sensing effecti...Dynamic spectrum access policy is crucial in improving the performance of over- lay cognitive radio networks. Most of the previ- ous works on spectrum sensing and dynamic spe- ctrum access consider the sensing effective- ness and spectrum utilization as the design cri- teria, while ignoring the energy related issues and QoS constraints. In this article, we propose a QoS provisioning energy saving dynamic acc- ess policy using stochastic control theory con- sidering the time-varying characteristics of wir- eless channels because of fading and mobility. The proposed scheme determines the sensing action and selects the optimal spectrum using the corresponding power setting in each decis- ion epoch according to the channel state with the objective being to minimise both the flame error rate and energy consumption. We use the Hidden Markov Model （HMM） to model a wir- eless channel, since the channel state is not dir- ectly observable at the receiver, but is instead embedded in the received signal. The proced- ure of dynamic spectrum access is formulated as a Markov decision process which can be sol- ved using linear programming and the primal- dual index heuristic algorithm, and the obta- ined policy has an index-ability property that can be easily implemented in real systems. Sim- ulation results are presented to show the per- formance improvement caused by the propo- sed approach.展开更多
We propose a distributed closedloop power control scheme for a cognitive radio network(CRN) based on our developed state space model of the CRN. The whole power control process is separated into outer control loop and...We propose a distributed closedloop power control scheme for a cognitive radio network(CRN) based on our developed state space model of the CRN. The whole power control process is separated into outer control loop and inner control loop in order to solve different problem. In outer loop, the interference temperature(IT) constraint is transformed to a performance index minimized by a state feedback controller to obtain an appropriate target signal to interference plus noise ratio(SINR) of secondary user(SU). For ideal channel model and random time-varying channel model, our designed controller is a linear quadratic regulator(LQR) and a linear quadratic Gaussian(LQG) regulator respectively. While in inner loop, SU controls its transmit power to make the instantaneous SINR track the corresponding target and ensure the IT constraint under the limited threshold. The closed-loop stability of the CRN is proved and the performance of proposed control scheme is presented by computer simulations, which shows that this scheme can effectively guarantee both the requirement of SINR and IT constraint for all SUs.展开更多
文摘This paper discusses some issues on human reliability model of time dependent human behavior. Some results of the crew reliability experiment on Tsinghua training simulator in China are given, Meanwhile, a case of calculation for human error probability during anticipated transient without scram (ATWS) based on the data drew from the recent experiment is offered.
文摘Taken discourse production as the research objective,it holds that discourse production is dynamic in human communication.It attempts to analyze the dynamics on the basis of Relevance-adaption model from the perspective of cognitive pragmatics and explain the role of the context dynamics that plays in the discourse production.
文摘如何提高动作技能习得效率是动作学习与控制(Motor Learning and Control)领域的重点课题。已有研究肯定了触觉学习的有益性,但干预方案缺乏稳定性或练习内容简单,为此研制了一种新型体育器材来创建有效的触觉学习条件,然后开展为期2周、每周4次的实验干预,发现:在缺乏动作概念指导的情况下触觉学习产生的习得效率较低,而一旦练习者建立了动作概念,触觉学习明显产生了比认知学习更高的习得效率,而且认知学习有利于初学者掌握复杂动作技能,触觉学习有利于掌握简单动作技能,所以建议初学者采用“概念打底,触觉推进”的动作技能学习策略。
文摘English language learners' pragmatic competence is related to their success incross-cultural communication. Cognitive approaches, mainly the Noticing Hypothesis and Analysis/Control Model, have provided some insights into the question of how to effectively develop second language(L2) learners' pragmatic competence. Empirical studies based on cognitive theoretical constructs suggest that pragmatic activitiesthat draw learners' attention and help them control attention to relevant and appropriate information and integrate those forms in real time of communication contribute to the development of interlanguage pragmatic competence.
文摘Two pieces of news reports on Yangtze Sunken Ship event are analyzed in this essay to prove the influence of context model in news reports discourse by comparative analysis approach. Through illustrating the different expressions in these reports discourse, the process how cognition(or context model) influences and determines the production and understanding of discourse has been demonstrated.
文摘We study cooperative spectrum sensing in cognitive radio (CR) networks using the hidden Markov model (HMM) for opportunistic spectrum access (OSA). We assume that the primary channel operates in a time division multiple address (TDMA) manner. Thus, spectrum sensing is operating in a slot-by-slot basis. In contrast to the conventional Bayesian updating using only one observation, in this work, we propose to perform the update in a concatenated fashion with all the observations available from the secondary users (SUs). In the proposed scheme, a predefined threshold on the belief is used for determining the channel activity. With the threshold, the proposed scheme is more flexible in the system operation than the simple majority vote scheme, in which no such threshold is available. We compare, by simulations, the performance of the proposed concatenated update scheme with that of the majority vote scheme and show that the probabilities of correctly detecting a busy state and an idle state are about 1 as the number of SUs is as large as 15, so the effects of the further increase in the number of SUs are limited.
基金Project supported by the National Natural Science Foundation of China(Grant No.61301179)the Doctorial Programs Foundation of the Ministry of Education of China(Grant No.20110203110011)the 111 Project(Grant No.B08038)
文摘A cognitive radio（CR） network with energy harvesting（EH） is considered to improve both spectrum efficiency and energy efficiency. A hidden Markov model（HMM） is used to characterize the imperfect spectrum sensing process. In order to maximize the whole satisfaction degree（WSD） of the cognitive radio network, a tradeoff between the average throughput of the secondary user（SU） and the interference to the primary user（PU） is analyzed. We formulate the satisfaction degree optimization problem as a mixed integer nonlinear programming（MINLP） problem. The satisfaction degree optimization problem is solved by using differential evolution（DE） algorithm. The proposed optimization problem allows the network to adaptively achieve the optimal solution based on its required quality of service（Qos）. Numerical results are given to verify our analysis.
基金supported by the National Natural Science Foundation of China under Grant No.61101107the Beijing Higher Education Young Elite Teacher Project under Grant No.YETP0439
文摘Dynamic spectrum access policy is crucial in improving the performance of over- lay cognitive radio networks. Most of the previ- ous works on spectrum sensing and dynamic spe- ctrum access consider the sensing effective- ness and spectrum utilization as the design cri- teria, while ignoring the energy related issues and QoS constraints. In this article, we propose a QoS provisioning energy saving dynamic acc- ess policy using stochastic control theory con- sidering the time-varying characteristics of wir- eless channels because of fading and mobility. The proposed scheme determines the sensing action and selects the optimal spectrum using the corresponding power setting in each decis- ion epoch according to the channel state with the objective being to minimise both the flame error rate and energy consumption. We use the Hidden Markov Model （HMM） to model a wir- eless channel, since the channel state is not dir- ectly observable at the receiver, but is instead embedded in the received signal. The proced- ure of dynamic spectrum access is formulated as a Markov decision process which can be sol- ved using linear programming and the primal- dual index heuristic algorithm, and the obta- ined policy has an index-ability property that can be easily implemented in real systems. Sim- ulation results are presented to show the per- formance improvement caused by the propo- sed approach.
基金supported by the National Natural Science Foundation of China (Grant No. 61571209)
文摘We propose a distributed closedloop power control scheme for a cognitive radio network(CRN) based on our developed state space model of the CRN. The whole power control process is separated into outer control loop and inner control loop in order to solve different problem. In outer loop, the interference temperature(IT) constraint is transformed to a performance index minimized by a state feedback controller to obtain an appropriate target signal to interference plus noise ratio(SINR) of secondary user(SU). For ideal channel model and random time-varying channel model, our designed controller is a linear quadratic regulator(LQR) and a linear quadratic Gaussian(LQG) regulator respectively. While in inner loop, SU controls its transmit power to make the instantaneous SINR track the corresponding target and ensure the IT constraint under the limited threshold. The closed-loop stability of the CRN is proved and the performance of proposed control scheme is presented by computer simulations, which shows that this scheme can effectively guarantee both the requirement of SINR and IT constraint for all SUs.
