The optical wireless communication (OWC) is afading channel because of the effect of atmosphericattenuation. We introduce a cumulant-based adaptive detection technique to providehigh performance for OWC. The received ...The optical wireless communication (OWC) is afading channel because of the effect of atmosphericattenuation. We introduce a cumulant-based adaptive detection technique to providehigh performance for OWC. The received signalof OWC over strong turbulence channels is assumedto be a mixture of K-distributed fading andGaussian distributed thermal noise. In order tomitigate the fading induced by turbulence, thedecision threshold-updating algorithm based onsecond and higher order cumulants is proposed,which is able to operate in an unknown turbulenceenvironment. The performance of the adaptiveprocessing scheme has been evaluated by meansof Monte Carlo simulations. It is shown that theproposed approach proves valuable for a limitednumber K of memory data.展开更多
In order to construct the trusted network and realize the trust of network behavior,a new multi-dimensional behavior measurement model based on prediction and control is presented.By using behavior predictive equation...In order to construct the trusted network and realize the trust of network behavior,a new multi-dimensional behavior measurement model based on prediction and control is presented.By using behavior predictive equation,individual similarity function,group similarity function,direct trust assessment function,and generalized predictive control,this model can guarantee the trust of an end user and users in its network.Compared with traditional measurement model,the model considers different characteristics of various networks.The trusted measurement policies established according to different network environments have better adaptability.By constructing trusted group,the threats to trusted group will be reduced greatly.Utilizing trusted group to restrict individuals in network can ensure the fault tolerance of trustworthiness of trusted individuals and group.The simulation shows that this scheme can support behavior measurement more efficiently than traditional ones and the model resists viruses and Trojans more efficiently than older ones.展开更多
针对卫星编队重构问题,提出了一种具有随机不确定性、推力约束和避障能力的随机模型预测控制(Stochastic model predictive control,SMPC)方法。由于不确定性的概率是有限的,足以违反约束条件,给随机不确定性的考虑带来了巨大的挑战。S...针对卫星编队重构问题,提出了一种具有随机不确定性、推力约束和避障能力的随机模型预测控制(Stochastic model predictive control,SMPC)方法。由于不确定性的概率是有限的,足以违反约束条件,给随机不确定性的考虑带来了巨大的挑战。SMPC利用概率不确定性描述来定义机会约束,通过引入约束违反概率,为处理约束的随机效应提供了一种有效的方法,且上述方法仅需知道不确定性的均值和方差。将SMPC问题转化为确定性凸问题,提出了一种切比雪夫不等式,将机会约束转化为确定性约束。最后对卫星编队重构问题进行了数值模拟,验证了SMPC算法的可行性和优越性。展开更多
目的:探讨慢性病病案管理模式对我国社区老年抑郁症患者疗效的影响。方法:采用随机对照研究方法,将年龄≥60岁,符合美国《精神障碍诊断与统计手册》(Diagnostic and Statistical Manual of Mental Disorder,Fourthedition,DSM-Ⅳ)抑郁...目的:探讨慢性病病案管理模式对我国社区老年抑郁症患者疗效的影响。方法:采用随机对照研究方法,将年龄≥60岁,符合美国《精神障碍诊断与统计手册》(Diagnostic and Statistical Manual of Mental Disorder,Fourthedition,DSM-Ⅳ)抑郁症诊断标准的120例老年抑郁症患者,随机分成干预组(N=60)和对照组(N=60)。干预组实行慢性病病案管理模式,即精神科医生、社区医生和病案管理员共同对老年抑郁症患者实施综合治疗方案,如健康教育、心理治疗和药物治疗等;对照组按照目前社区日常的医学方式进行。在治疗前,治疗第2、4、6、8、12周末分别应用汉密尔顿抑郁量表(Hamilton Depression Scale,HAMD-17)、临床疗效总评量表(ClinicalGlobalImpression,CGI)、治疗副反应量表(Treatment Emergent Symptom Scale,TESS)对两组患者的疗效和药物不良反应进行评定。结果:在治疗12周末,干预组患者HAMD-17总分[(14.19±7.66)vs.(24.93±5.86)]和CGI-GI评分[(1.61±0.92)vs.(3.43±1.42)]均低于对照组(均P<0.01);干预组有效率(83.1%vs.39.3%)、临床治愈率(27.1%vs.5.4%)高于对照组(均P<0.01);干预组患者坚持服药率高于对照组(98.3%vs.35%,P<0.01);两组患者药物不良反应轻微,且差异无统计学意义(P>0.05)。结论:应用慢性病病案管理模式可以有效地减轻抑郁症状,增加抗抑郁药的使用,提高治疗效果。展开更多
文摘The optical wireless communication (OWC) is afading channel because of the effect of atmosphericattenuation. We introduce a cumulant-based adaptive detection technique to providehigh performance for OWC. The received signalof OWC over strong turbulence channels is assumedto be a mixture of K-distributed fading andGaussian distributed thermal noise. In order tomitigate the fading induced by turbulence, thedecision threshold-updating algorithm based onsecond and higher order cumulants is proposed,which is able to operate in an unknown turbulenceenvironment. The performance of the adaptiveprocessing scheme has been evaluated by meansof Monte Carlo simulations. It is shown that theproposed approach proves valuable for a limitednumber K of memory data.
基金This work was supported by the National Basic Research Pro-gram of China under Crant No.2007CB311100 Funds of Key Lab of Fujlan Province University Network Security and Cryp- toll1009+3 种基金 the National Science Foundation for Young Scholars of China under Crant No.61001091 Beijing Nature Science Foundation under Crant No. 4122012 ＂Next-Generation Broad-band Wireless Mobile Communication Network＂ National Sci-ence and Technology Major Special Issue Funding under Grant No. 2012ZX03002003 Funding Program for Academic tturmn Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality of Chi-na.
文摘In order to construct the trusted network and realize the trust of network behavior,a new multi-dimensional behavior measurement model based on prediction and control is presented.By using behavior predictive equation,individual similarity function,group similarity function,direct trust assessment function,and generalized predictive control,this model can guarantee the trust of an end user and users in its network.Compared with traditional measurement model,the model considers different characteristics of various networks.The trusted measurement policies established according to different network environments have better adaptability.By constructing trusted group,the threats to trusted group will be reduced greatly.Utilizing trusted group to restrict individuals in network can ensure the fault tolerance of trustworthiness of trusted individuals and group.The simulation shows that this scheme can support behavior measurement more efficiently than traditional ones and the model resists viruses and Trojans more efficiently than older ones.
文摘针对卫星编队重构问题,提出了一种具有随机不确定性、推力约束和避障能力的随机模型预测控制(Stochastic model predictive control,SMPC)方法。由于不确定性的概率是有限的,足以违反约束条件,给随机不确定性的考虑带来了巨大的挑战。SMPC利用概率不确定性描述来定义机会约束,通过引入约束违反概率,为处理约束的随机效应提供了一种有效的方法,且上述方法仅需知道不确定性的均值和方差。将SMPC问题转化为确定性凸问题,提出了一种切比雪夫不等式,将机会约束转化为确定性约束。最后对卫星编队重构问题进行了数值模拟,验证了SMPC算法的可行性和优越性。
