期刊文献+
共找到3,348篇文章
< 1 2 168 >
每页显示 20 50 100
Measurement Research Based on Bayesian Structural Equation Cognitive Model
1
作者 Shuixian Fei Sanzhi Shi +4 位作者 Jixin Li Jiali Zheng Xinyi Yu Yifan Huang Xiang Li 《Journal of Applied Mathematics and Physics》 2024年第4期1163-1177,共15页
The Bayesian structural equation model integrates the principles of Bayesian statistics, providing a more flexible and comprehensive modeling framework. In exploring complex relationships between variables, handling u... The Bayesian structural equation model integrates the principles of Bayesian statistics, providing a more flexible and comprehensive modeling framework. In exploring complex relationships between variables, handling uncertainty, and dealing with missing data, the Bayesian structural equation model demonstrates unique advantages. Therefore, Bayesian methods are used in this paper to establish a structural equation model of innovative talent cognition, with the measurement of college students’ cognition of innovative talent being studied. An in-depth analysis is conducted on the effects of innovative self-efficacy, social resources, innovative personality traits, and school education, aiming to explore the factors influencing college students’ innovative talent. The results indicate that innovative self-efficacy plays a key role in perception, social resources are significantly positively correlated with the perception of innovative talents, innovative personality tendencies and school education are positively correlated with the perception of innovative talents, but the impact is not significant. 展开更多
关键词 Bayesian Structural Equation model Innovative Talents Measure of cognition Innovative Self-Efficacy Social Resources
下载PDF
Visual Representation and Cognitive Models in Information Visualization
2
作者 Yingquan Wang Mustaffa Halabi Azahari 《Journal of Electronic Research and Application》 2024年第4期115-120,共6页
As a branch of computer science,information visualization aims to help users understand and analyze complex data through graphical interfaces and interactive technologies.Information visualization primarily includes v... As a branch of computer science,information visualization aims to help users understand and analyze complex data through graphical interfaces and interactive technologies.Information visualization primarily includes various visual structures such as time-series structures,spatial relationship structures,statistical distribution structures,and geographic map structures,each with unique functions and application scenarios.To better explain the cognitive process of visualization,researchers have proposed various cognitive models based on interaction mechanisms,visual perception steps,and novice use of visualization.These models help understand user cognition in information visualization,enhancing the effectiveness of data analysis and decision-making. 展开更多
关键词 Information visualization Visual structures cognitive models Interaction design
下载PDF
Rotating magnetic field inhibits Aβ protein aggregation and alleviates cognitive impairment in Alzheimer’s disease mice
3
作者 Ruo-Wen Guo Wen-Jing Xie +5 位作者 Biao Yu Chao Song Xin-Miao Ji Xin-Yu Wang Mei Zhang Xin Zhang 《Zoological Research》 SCIE CSCD 2024年第4期924-936,共13页
Amyloid beta(Aβ)monomers aggregate to form fibrils and amyloid plaques,which are critical mechanisms in the pathogenesis of Alzheimer’s disease(AD).Given the important role of Aβ1-42 aggregation in plaque formation... Amyloid beta(Aβ)monomers aggregate to form fibrils and amyloid plaques,which are critical mechanisms in the pathogenesis of Alzheimer’s disease(AD).Given the important role of Aβ1-42 aggregation in plaque formation,leading to brain lesions and cognitive impairment,numerous studies have aimed to reduce Aβaggregation and slow AD progression.The diphenylalanine(FF)sequence is critical for amyloid aggregation,and magnetic fields can affect peptide alignment due to the diamagnetic anisotropy of aromatic rings.In this study,we examined the effects of a moderate-intensity rotating magnetic field(RMF)on Aβaggregation and AD pathogenesis.Results indicated that the RMF directly inhibited Aβamyloid fibril formation and reduced Aβ-induced cytotoxicity in neural cells in vitro.Using the AD mouse model APP/PS1,RMF restored motor abilities to healthy control levels and significantly alleviated cognitive impairments,including exploration and spatial and non-spatial memory abilities.Tissue examinations demonstrated that RMF reduced amyloid plaque accumulation,attenuated microglial activation,and reduced oxidative stress in the APP/PS1 mouse brain.These findings suggest that RMF holds considerable potential as a non-invasive,high-penetration physical approach for AD treatment. 展开更多
关键词 lzheimer’s disease Rotating magnetic field Amyloid-β cognitive function Alzheimer’s disease animal models
下载PDF
THEORY AND IMPLEMENTATION OF ICAI COGNITIVE MODEL BASED ON MEANING
4
作者 何丕廉 侯越先 《Transactions of Tianjin University》 EI CAS 1999年第2期36-39,共4页
Cognitive models must be able to adapt the students learning behaviors dynamically.In our point of view,the processes of learning and understanding are,in nature,the procedure that gains the meaning of the object to b... Cognitive models must be able to adapt the students learning behaviors dynamically.In our point of view,the processes of learning and understanding are,in nature,the procedure that gains the meaning of the object to be learned.So,ICAI cognitive models should reflect the meaning structure of the domain knowledge in students mind.According to this view,we developed the meaning theory of Ludwig Wittgenstein,and proposed the concept of meaning conjoinism.On the basis of the meaning conjoinism we proposed a meaning oriented ICAI cognitive model and its corresponding teaching tactics.Furthermore,we developed an ICAI system named Thinking and the efficiency of our proposal has been demonstrated. 展开更多
关键词 meaning oriented meaning conjoinism cognitive model teaching tactics ICAI
下载PDF
APPLICATION OF HUMAN COGNITIVE MODEL FOR TIME DEPENDENT OPERATOR BEHAVIOR IN CHINESE NPP
5
作者 黄祥瑞 高佳 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1998年第1期31-35,共5页
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
关键词 reliability analysis cognitive model human error behavior probabilistic safety assessment human machine interaction
下载PDF
Research on cognitive model of English major writing course based on the Internet
6
作者 贾虹 《Sino-US English Teaching》 2009年第1期14-17,共4页
With the development of Internet technology, network is more and more common in the teaching process. On the analysis of teaching status of English major writing course and in the guide of cognitive linguistics and co... With the development of Internet technology, network is more and more common in the teaching process. On the analysis of teaching status of English major writing course and in the guide of cognitive linguistics and constructivism, the paper studies the use of the internet in English major writing teaching cognitive model. 展开更多
关键词 INTERNET the teaching of English major writing cognitive model
下载PDF
Mesenchymal stem cell-derived exosomes promote neurogenesis and cognitive function recovery in a mouse model of Alzheimer’s disease 被引量:26
7
作者 Edwin E. Reza-Zaldivar Mercedes A. Hernández-Sapiéns +6 位作者 Yanet K. Gutiérrez-Mercado Sergio Sandoval-ávila Ulises Gomez-Pinedo Ana L. Márquez-Aguirre Estefanía Vázquez-Méndez Eduardo Padilla-Camberos Alejandro A. Canales-Aguirre 《Neural Regeneration Research》 SCIE CAS CSCD 2019年第9期1626-1634,共9页
Studies have shown that mesenchymal stem cell-derived exosomes can enhance neural plasticity and improve cognitive impairment.The purpose of this study was to investigate the effects of mesenchymal stem cell-derived e... Studies have shown that mesenchymal stem cell-derived exosomes can enhance neural plasticity and improve cognitive impairment.The purpose of this study was to investigate the effects of mesenchymal stem cell-derived exosomes on neurogenesis and cognitive capacity in a mouse model of Alzheimer’s disease.Alzheimer’s disease mouse models were established by injection of beta amyloid 1?42 aggregates into dentate gyrus bilaterally.Morris water maze and novel object recognition tests were performed to evaluate mouse cognitive deficits at 14 and 28 days after administration.Afterwards,neurogenesis in the subventricular zone was determined by immunofluorescence using doublecortin and PSA-NCAM antibodies.Results showed that mesenchymal stem cells-derived exosomes stimulated neurogenesis in the subventricular zone and alleviated beta amyloid 1?42-induced cognitive impairment,and these effects are similar to those shown in the mesenchymal stem cells.These findings provide evidence to validate the possibility of developing cell-free therapeutic strategies for Alzheimer’s disease.All procedures and experiments were approved by Institutional Animal Care and Use Committee(CICUAL)(approval No.CICUAL 2016-011)on April 25,2016. 展开更多
关键词 Alzheimer’s DISEASE neurodegenerative DISEASE cognitive impairment memory Alzheimer’s DISEASE MOUSE model mesenchymal stem cell EXOSOMES NEUROGENESIS cognitive improvement cell-free therapy neural regeneration
下载PDF
Amelioration of Alzheimer's disease pathology and cognitive deficits by immunomodulatory agents in animal models of Alzheimer's disease 被引量:7
8
作者 Bridget Martinez Philip V.Peplow 《Neural Regeneration Research》 SCIE CAS CSCD 2019年第7期1158-1176,共19页
The most common age-related neurodegenerative disease is Alzheimer's disease(AD) characterized by aggregated amyloid-β(Aβ) peptides in extracellular plaques and aggregated hyperphosphorylated tau protein in intr... The most common age-related neurodegenerative disease is Alzheimer's disease(AD) characterized by aggregated amyloid-β(Aβ) peptides in extracellular plaques and aggregated hyperphosphorylated tau protein in intraneuronal neurofibrillary tangles,together with loss of cholinergic neurons,synaptic alterations,and chronic inflammation within the brain.These lead to progressive impairment of cognitive function.There is evidence of innate immune activation in AD with microgliosis.Classically-activated microglia(M1 state) secrete inflammatory and neurotoxic mediators,and peripheral immune cells are recruited to inflammation sites in the brain.The few drugs approved by the US FDA for the treatment of AD improve symptoms but do not change the course of disease progression and may cause some undesirable effects.Translation of active and passive immunotherapy targeting Aβ in AD animal model trials had limited success in clinical trials.Treatment with immunomodulatory/anti-inflammatory agents early in the disease process,while not preventive,is able to inhibit the inflammatory consequences of both Aβ and tau aggregation.The studies described in this review have identified several agents with immunomodulatory properties that alleviated AD pathology and cognitive impairment in animal models of AD.The majority of the animal studies reviewed had used transgenic models of early-onset AD.More effort needs to be given to creat models of late-onset AD.The effects of a combinational therapy involving two or more of the tested pharmaceutical agents,or one of these agents given in conjunction with one of the cell-based therapies,in an aged animal model of AD would warrant investigation. 展开更多
关键词 Alzheimer’s disease NEUROPATHOLOGY cognitive deficits behavioral deficits IMMUNOMODULATORY agents animal models AMYLOID deposits GLIOSIS
下载PDF
Cold water swimming pretreatment reduces cognitive deficits in a rat model of traumatic brain injury 被引量:4
9
作者 Zi-wei Zhou Ya-dan Li +3 位作者 Wei-wei Gao Jie-li Chen Shu-yuan Yue Jian-ning Zhang 《Neural Regeneration Research》 SCIE CAS CSCD 2017年第8期1322-1328,共7页
A moderate stress such as cold water swimming can raise the tolerance of the body to potentially injurious events. However, little is known about the mechanism of beneficial effects induced by moderate stress. In this... A moderate stress such as cold water swimming can raise the tolerance of the body to potentially injurious events. However, little is known about the mechanism of beneficial effects induced by moderate stress. In this study, we used a classic rat model of traumatic brain injury to test the hypothesis that cold water swimming preconditioning improved the recovery of cognitive functions and explored the mechanisms. Results showed that after traumatic brain injury, pre-conditioned rats(cold water swimming for 3 minutes at 4℃) spent a significantly higher percent of times in the goal quadrant of cold water swim, and escape latencies were shorter than for non-pretreated rats. The number of circulating endothelial progenitor cells was significantly higher in pre-conditioned rats than those without pretreatment at 0, 3, 6 and 24 hours after traumatic brain injury. Immunohistochemical staining and Von Willebrand factor staining demonstrated that the number of CD34~+ stem cells and new blood vessels in the injured hippocampus tissue increased significantly in pre-conditioned rats. These data suggest that pretreatment with cold water swimming could promote the proliferation of endothelial progenitor cells and angiogenesis in the peripheral blood and hippocampus. It also ameliorated cognitive deficits caused by experimental traumatic brain injury. 展开更多
关键词 nerve regeneration cold water swimming cognitive deficits endothelial progenitor cells angiogenesis neural repair stress Morriswater maze fluid percussion injury model CD34 Von Willebrand factor neural regeneration
下载PDF
Modeling of cognitive framework in time-stressed decision making 被引量:3
10
作者 Wang Li Wang Mingzhe 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2009年第5期992-1000,共9页
An approach for modeling a human cognitive framework in time-stressed decision making is presented. The recognitive and metacognitive processes that represent the cognitive framework are modeled by the colored Petri n... An approach for modeling a human cognitive framework in time-stressed decision making is presented. The recognitive and metacognitive processes that represent the cognitive framework are modeled by the colored Petri nets (CPNs). A structural and behavioral analysis method is adopted to obtain the static and dynamic property used to verify the CPNs model of the cognitive framework. Finally, an example from the command and control radar recognition system is used to evaluate the feasibility and availability of the CPNs model adopted in practical systems. 展开更多
关键词 cognitive framework metacognition colored Petri nets modeling and verification decision making.
下载PDF
Diabetes and cognitive decline:Challenges and future direction
11
作者 Norhamidar Ab-Hamid Norsuhana Omar +1 位作者 Che Aishah Nazariah Ismail Idris Long 《World Journal of Diabetes》 SCIE 2023年第6期795-807,共13页
There is growing evidence that diabetes can induce cognitive decline and dementia.It is a slow,progressive cognitive decline that can occur in any age group,but is seen more frequently in older individuals.Symptoms re... There is growing evidence that diabetes can induce cognitive decline and dementia.It is a slow,progressive cognitive decline that can occur in any age group,but is seen more frequently in older individuals.Symptoms related to cognitive decline are worsened by chronic metabolic syndrome.Animal models are frequently utilized to elucidate the mechanisms of cognitive decline in diabetes and to assess potential drugs for therapy and prevention.This review addresses the common factors and pathophysiology involved in diabetes-related cognitive decline and outlines the various animal models used to study this condition. 展开更多
关键词 Diabetes mellitus Insulin signaling Macrovascular disease Microvascular disease Animal models cognitive decline PATHOPHYSIOLOGY
下载PDF
MODELING RADIO RESOURCE MANAGEMENT IN COGNITIVE RADIO SYSTEM BASED ON OFDMA USING COLORED PETRI NET 被引量:2
12
作者 Lu Yanhui Zhang Yuqiong Yang Shouyi Mu Xiaomin 《Journal of Electronics(China)》 2010年第5期671-676,共6页
Cognitive Radio(CR) system based on Orthogonal Frequency Division Multiple Access(OFDMA),such as Wireless Regional Area Networks(WRAN) and Worldwide Interoperability for Microwave Access(WiMAX),often attempt to improv... Cognitive Radio(CR) system based on Orthogonal Frequency Division Multiple Access(OFDMA),such as Wireless Regional Area Networks(WRAN) and Worldwide Interoperability for Microwave Access(WiMAX),often attempt to improve performance via dynamic radio resource management,which is characterized as concurrent processing of different traffic and nondeterministic system capacity.It is essential to design and evaluate such complex system using proper modeling and analysis tools.In the previous work,most of the communication systems were modeled as Markov Chain(MC) and Stochastic Petri Nets(SPN),which have the explicit limitation in evaluating adaptive OFDMA CR system with wide area traffic.In this paper,we develop an executable top-down hier-archical Colored Petri Net(CPN) model for adaptive OFDMA CR system,and analyze its performance using CPN tools.The results demonstrate that the CPN can model different radio resource manage-ment algorithms in CR Systems,and the CPN tools require less computational effort than Markov model using Matlab,with its flexibility and adaptability to the traffics which arrival interval and processing time are not exponentially distributed. 展开更多
关键词 cognitive Radio (CR) Dynamic Radio Resource Management (RRM) Colored Petri Net (CPN) modeling and evaluation
下载PDF
Cat Swarm with Fuzzy Cognitive Maps for Automated Soil Classification
13
作者 Ashit Kumar Dutta Yasser Albagory +2 位作者 Manal Al Faraj Majed Alsanea Abdul Rahaman Wahab Sait 《Computer Systems Science & Engineering》 SCIE EI 2023年第2期1419-1432,共14页
Accurate soil prediction is a vital parameter involved to decide appro-priate crop,which is commonly carried out by the farmers.Designing an auto-mated soil prediction tool helps to considerably improve the efficacy of... Accurate soil prediction is a vital parameter involved to decide appro-priate crop,which is commonly carried out by the farmers.Designing an auto-mated soil prediction tool helps to considerably improve the efficacy of the farmers.At the same time,fuzzy logic(FL)approaches can be used for the design of predictive models,particularly,Fuzzy Cognitive Maps(FCMs)have involved the concept of uncertainty representation and cognitive mapping.In other words,the FCM is an integration of the recurrent neural network(RNN)and FL involved in the knowledge engineering phase.In this aspect,this paper introduces effective fuzzy cognitive maps with cat swarm optimization for automated soil classifica-tion(FCMCSO-ASC)technique.The goal of the FCMCSO-ASC technique is to identify and categorize seven different types of soil.To accomplish this,the FCMCSO-ASC technique incorporates local diagonal extrema pattern(LDEP)as a feature extractor for producing a collection of feature vectors.In addition,the FCMCSO model is applied for soil classification and the weight values of the FCM model are optimally adjusted by the use of CSO algorithm.For exam-ining the enhanced soil classification outcomes of the FCMCSO-ASC technique,a series of simulations were carried out on benchmark dataset and the experimen-tal outcomes reported the enhanced performance of the FCMCSO-ASC technique over the recent techniques with maximum accuracy of 96.84%. 展开更多
关键词 Soil classification intelligent models fuzzy cognitive maps cat swarm optimization fuzzy logic
下载PDF
An enriched environment reduces hippocampal inflammatory response and improves cognitive function in a mouse model of stroke 被引量:2
14
作者 Hong-Yu Zhou Ya-Ping Huai +7 位作者 Xing Jin Ping Yan Xiao-Jia Tang Jun-Ya Wang Nan Shi Meng Niu Zhao-Xiang Meng Xin Wang 《Neural Regeneration Research》 SCIE CAS CSCD 2022年第11期2497-2503,共7页
An enriched environment is used as a behavio ral intervention therapy that applies sensory,motor,and social stimulation,and has been used in basic and clinical research of va rious neurological diseases.In this study,... An enriched environment is used as a behavio ral intervention therapy that applies sensory,motor,and social stimulation,and has been used in basic and clinical research of va rious neurological diseases.In this study,we established mouse models of photothrombotic stroke and,24 hours later,raised them in a standard,enriched,or isolated environment for 4 weeks.Compared with the mice raised in a standard environment,the cognitive function of mice raised in an enriched environment was better and the pathological damage in the hippocampal CA1 region was remarkably alleviated.Furthermore,protein expression levels of tumor necrosis factor receptor-associated factor 6,nuclear factorκB p65,interleukin-6,and tumor necrosis factorα,and the mRNA expression level of tumor necrosis factor receptor-associated factor 6 were greatly lower,while the expression level of miR-146a-5p was higher.Compared with the mice raised in a standard environment,changes in these indices in mice raised in an isolated environment were opposite to mice raised in an enriched environment.These findings suggest that different living environments affect the hippocampal inflammatory response and cognitive function in a mouse model of stro ke.An enriched environment can improve cognitive function following stroke through up-regulation of miR-146a-5p expression and a reduction in the inflammatory response. 展开更多
关键词 cognitive function enriched environment isolated environment miR-146a-5p NEUROINFLAMMATION nuclear factorκB p65 photothrombotic model STROKE tumor necrosis factor receptor-associated factor 6
下载PDF
Cognitive deficits in schizophrenia:from pharmacology to neurocognitive models 被引量:1
15
作者 Zhemeng Wu Qian Wang 《Journal of Translational Neuroscience》 2018年第1期1-11,共11页
Schizophrenia is a typical mental disorder characterized by cognitive,social,and emotional impairments and by psychotic symptoms.For nearly a century,there have been ongoing discussions on the anatomical-functional co... Schizophrenia is a typical mental disorder characterized by cognitive,social,and emotional impairments and by psychotic symptoms.For nearly a century,there have been ongoing discussions on the anatomical-functional connections between brain abnormalities and symptoms in patients with schizophrenia.Neuroimaging studies in such patients show abnormalities in the prefrontal cortex(PFC),a brain region that acts as an executive center in cognition processing.The disrupted brain connectivity between PFC and other brain structures(such as the limbic system,basal ganglia and thalamus)results in faulty information processing and cognition deficits.Dopamine receptors,which have historically acted as vital targets in schizophrenia therapies,have complex roles in cognition.Here we reviewed dopamine's role as a widespread neurotransmitter mediating the PFC-cognitive system.The imbalance of brain dopamine level,especially the abnormal D1/D2receptors ratio,leads to dysfunctions in brain connectivity in patients with schizophrenia.Recent neurocognitive modeling studies suggest the imbalance of dopamine receptors affects the internal noise within brain networks,which may lead to reduced signal-to-noise ratio in the PFC neuron populations.Going forward,more researches focusing on the relationship between pharmacology and neurocognitive models are needed,in an effort to identify more effective and efficient ways to treat cognitive impairment in patients with schizophrenia. 展开更多
关键词 DOPAMINE INTERNAL noise model SCHIZOPHRENIA cognitive deficits
下载PDF
Propagation Modelling Using Integral Equation Methods to Enable Co-existence and Address Physical Layer Security Issues in Cognitive Radio
16
作者 Eamonn O. Nuallain 《International Journal of Communications, Network and System Sciences》 2011年第3期139-146,共8页
In this paper it is envisaged that cognitive radios (CRs) consult a supporting network infrastructure for per-mission to transmit. The network server either grants or rejects these requests by estimating, from the CR... In this paper it is envisaged that cognitive radios (CRs) consult a supporting network infrastructure for per-mission to transmit. The network server either grants or rejects these requests by estimating, from the CR’s geo-location and antenna features, the likely impact its transmission would have on incumbents and other CR devices. This decision would be based on a real-time radio environment map [1] which would be kept up to date with readings from CRs, sensors and dynamic radio propagation prediction. By this means coexistence with incumbents and other CRs can be satisfied. It is maintained here that integral-equation (IE) - based al-gorithms are suitable candidates for the propagation engine given their ‘automatic’ nature and that they can be implemented to give results arbitrarily close to the exact numerical solution. IE methods based on the Fast Multipole Method are examined as a likely route to achieve the accuracy and speed necessary for real-time propagation mapping. It is concluded that the results obtained using one of the most recent of these, the Field Extrapolation Method (FEXM) [2], are promising for rural/suburban profiles and could serve to enable co-existence, for example, in IEEE802.22 networks. It is also explained how dynamic propagation prediction can address some fundamental security threats to CR networks. 展开更多
关键词 cognitive Radio Propagation modeling INTEGRAL EQUATIONS
下载PDF
A Cognitive Model for Multi-Agent Collaboration
17
作者 Zhongzhi Shi Jianhua Zhang +1 位作者 Jinpeng Yue Xi Yang 《International Journal of Intelligence Science》 2014年第1期1-6,共6页
In multi-agent system, agents work together for solving complex tasks and reaching common goals. In this paper, we propose a cognitive model for multi-agent collaboration. Based on the cognitive model, an agent archit... In multi-agent system, agents work together for solving complex tasks and reaching common goals. In this paper, we propose a cognitive model for multi-agent collaboration. Based on the cognitive model, an agent architecture will also be presented. This agent has BDI, awareness and policy driven mechanism concurrently. These approaches are integrated in one agent that will make multi-agent collaboration more practical in the real world. 展开更多
关键词 cognitive model MULTI-AGENT COLLABORATION AWARENESS ABGP model POLICY Driven Strategy
下载PDF
Markov Model Based Jamming and Anti-Jamming Performance Analysis for Cognitive Radio Networks
18
作者 Wednel Cadeau Xiaohua Li Chengyu Xiong 《Communications and Network》 2014年第2期76-85,共10页
In this paper, we conduct a cross-layer analysis of both the jamming capability of the cognitiveradio-based jammers and the anti-jamming capability of the cognitive radio networks (CRN). We use a Markov chain to model... In this paper, we conduct a cross-layer analysis of both the jamming capability of the cognitiveradio-based jammers and the anti-jamming capability of the cognitive radio networks (CRN). We use a Markov chain to model the CRN operations in spectrum sensing, channel access and channel switching under jamming. With various jamming models, the jamming probabilities and the throughputs of the CRN are obtained in closed-form expressions. Furthermore, the models and expressions are simplified to determine the minimum and the maximum CRN throughput expressions under jamming, and to optimize important anti-jamming parameters. The results are helpful for the optimal anti-jamming CRN design. The model and the analysis results are verified by simulations. 展开更多
关键词 cognitive RADIO Dynamic Spectrum Access Jamming MARKOV model THROUGHPUT
下载PDF
On Constructing the Cognitive Model of Knowledge Acquisition in Globalization-Oriented Study
19
作者 ZHANG Jin-bao 《Sino-US English Teaching》 2013年第7期517-523,共7页
This paper which is directed to constructing the cognitive model of knowledge acquisition in view of the increasing need of globalization-oriented study, points out features of globalization-oriented study, and propos... This paper which is directed to constructing the cognitive model of knowledge acquisition in view of the increasing need of globalization-oriented study, points out features of globalization-oriented study, and proposes the importance and necessity for constructing the CMKAGS (cognitive model of knowledge acquisition in globalization-oriented study) which includes attention, background knowledge, and chunking memory that involves semantic chunking, information encoding as well as choice of information encoding. The cognitive model of knowledge acquisition in question aims at helping e-learners to memorize their learned knowledge and improve their studies effectively and efficiently, whether they study in enhanced conditions or in natural conditions 展开更多
关键词 globalization-oriented study cognitive psychology background knowledge cognitive model ofknowledge acquisition memory
下载PDF
On Evaluating the Efficacy of Predictive Models for Cognitive Radio Spectrum Availability in Nigeria
20
作者 Samuel Okegbile Adeniran Oluwaranti Segun Aina 《Wireless Engineering and Technology》 2018年第3期49-65,共17页
In order to avoid the undesired interference with the activities of the primary users in cognitive radio networks, the secondary users are required to be able to predict the behavior of the primary users so as to leav... In order to avoid the undesired interference with the activities of the primary users in cognitive radio networks, the secondary users are required to be able to predict the behavior of the primary users so as to leave the channel before the arrival of such licensed owner of the spectrum. While a number of existing literatures on cognitive radio spectrum prediction employ the use of propagation curves for predicting the spectrum holes otherwise known as TV white space, these models are built based on measurements conducted in regions that are different from Nigeria, suitability in terms of usage may therefore vary due to environmental factors and terrain profile. This work evaluates the efficacy of the developed model in predicting the cognitive spectrum availability in Nigeria. Models capable of predicting spectrum occupancy in the time domain using discrete-time two-state Markov chain with an appropriate Duty Cycle (DC) model and also a modified m-bell shaped exponential equation were formulated. The result obtained in all cases considered shows that the formulated models are appropriate to be used in any environment if the parameters were carefully extracted from the data. This work has also demonstrated that the accuracy of Markov chain models depends on the level of usage of a spectrum under consideration and may therefore not give desirable results when employed in some other spectrum. 展开更多
关键词 cognitive Device Predictive model SPECTRUM Management SPECTRUM OCCUPANCY TV WHITE Space
下载PDF
上一页 1 2 168 下一页 到第
使用帮助 返回顶部