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1.
由于多种因素影响刨煤机刨头位置的控制,本文提出了一种基于非线性自适应神经网络的刨煤机刨头位置控制系统,该系统采用了多传感器数据融合的方法,并将其应用在前馈反馈自适应神经网络中,其结果表明,与常规PID系统相比该系统能够消除静差从而更好地跟踪参考曲线。  相似文献   

2.
In addition to the main olfactory system, many vertebrates possess a vomeronasal system that conveys more specialized chemosensory information. Unlike the airborne, volatile stimuli detected by the main olfactory system, vomeronasal stimuli are typically proteins of the lipocalin family which bind small, volatile ligands. Despite the smaller number of vomeronasal receptor types, the projection patterns of the vomeronasal receptor neurons to multiple glomeruli in the accessory olfactory bulb appear to be more complicated than those of the main olfactory system. The vomeronasal system has a direct sub-neocortical projection to hypothalamic areas that mediates specific behavioural and hormonal responses to pheromonal stimuli. However, the integration and transmission of this information can be modulated by learning mechanisms. The aim of this article is to outline some of the functions of the vomeronasal system, and in particular to comment on recent advances in our understanding of how vomeronasal information is coded and processed.  相似文献   

3.
A comparative review of the different systems of units that are most usual in electromagnetism leads to the proposal of a new system of units. In this system, the gravitational constant acquires the role of an interaction constant, both for gravitational and electromagnetic interaction, as a result of a redefinition of electric charge. In this way, the new system of units extends in a natural manner to mechanics. The comparison between the gravitational and electromagnetic interactions is of particular relevance.  相似文献   

4.
A smart, automated forecasting system is a kind of expert system for generating forecasts wholly or partly without human intervention. A pilot-scale system is reported in this paper. The interventions are made by a rulebase which describes the actual intervention procedures of the London Business School Centre for Economic Forecasting on one of the major macroeconometric forecasting models for the U.K. economy. The rulebase is sufficiently general as to be applicable to any forecasting model. One difference of the pilot model reported in this paper from conventional models is that policy behaviour is described entirely by rules rather than equations. This allows the use of thresholds, floors, ceilings, and discontinuities.  相似文献   

5.
VBLAST系统中最大似然检测具有最优的检测性能,但是计算复杂度是一个NP难题.将量子Grover算法及Grover-Long算法用于VBLAST系统最大似然检测中,对算法的复杂度和性能进行了仿真分析,仿真结果表明Grover检测算法不仅能够对计算复杂度起到平方加速的效果,而且算法的检测性能逼近最大似然检测性能.  相似文献   

6.
为了利用RS码在高信噪比时的性能优势和Turbo码在低信噪比时的性能优势,从而进一步提高系统的抗误码性能,将RS码和Turbo码串行级联,并搭建了级联OFDM的WiMax系统进行仿真验证。高阶调制的解调采用最大对数似然比软解调算法,分析了级联码在不同调制模式下基于高斯白噪声和衰落信道的误码性能。仿真结果表明,该系统相对于RS码与卷积码的级联系统有2-3dB的编码增益,而且降低了Turbo码的迭代次数,克服了误码平台现象,达到降低系统复杂度和延时要求。  相似文献   

7.
Summary Crayfish escape from predators by a series of rapid tailflips. The production of this seemingly simple behavior involves the interaction of multiple neural control mechanisms. The rapid flexion phase of the first tailflip is a fixed action pattern that is always organized by giant command neurons. Subsequent reextension is a chain reflex mediated by sensory feedback from the initial flexion. All following tailflips are produced by a non-gialnt system which is activated in parallel with the giant system by the escape-initiating stimulus. Proper integration of the giant system and the non-giant system is mediated by a reaction time mechanism.  相似文献   

8.
采用DSP+FPGA结构实现数字电视条件接收系统的硬件设计;以安全性高、密钥量小、灵活性好的椭圆曲线密码算法(ECC)进行软件验证;以DSP实现ECC加密算法;以FPGA实现外围电路的嵌入式系统;充分利用FPGA的硬件连接方式和DSP强大的运算,采用软硬结合的方式,实现数字电视条件接收系统的设计,减少系统开发的时间与成本。仿真及实验表明:该算法稳定运行,并快于其它公钥密码算法。  相似文献   

9.
机器人间的协调是多机器人系统高效工作的关键,它取决于如何为机器人分配任务以及机器人如何执行任务。本文针对未知环境探测,提出了一种多机器人框架,并给出了一种衡量多机器人合作能力的时间效率曲线。仿真实验表明,该策略可满足未知环境探测任务,并能达到实时规划的要求。  相似文献   

10.
In this paper a system is proposed and applied to predicting silicon content in pig iron for a blast furnace. It combines an adaptive predictor with a knowledge base. On-line experiments show that the prediction accuracy of the system is much better than that of an experienced operator or of an adaptive predictor alone. Such a system will be helpful to operators in selecting desirable control methods.  相似文献   

11.
以广东东莞市土地为研究对象,采用“压力-状态-响应”(PSR)模型,共选取19个指标建立土地生态安全评价指标体系,运用Matlab软件编程并建立解释结构模型(ISM),利用所建立的模型对东莞市土地资源生态安全评价因素进行分析。模型分析得出:东莞市的土地生态安全评价因素被分成七级递阶结构,最低一级的因素是土地利用率,通过土地利用率的情况,影响经济密度,进而影响本地区的人口增长率和人口密度等因素,最终影响土地生态安全。最高一级是自然保护区的比重。这是由东莞市的现代化工业城市的特点所决定的。其中中间几级构成循环回路。土地生态安全评价因素之间的这种结构模型给政府以及决策部门为保持本地区土地生态安全提供了决策参考。  相似文献   

12.
According to Zurek, decoherence is a process resulting from the interaction between a quantum system and its environment; this process singles out a preferred set of states, usually called “pointer basis”, that determines which observables will receive definite values. This means that decoherence leads to a sort of selection which precludes all except a small subset of the states in the Hilbert space of the system from behaving in a classical manner: environment-induced-superselection—einselection—is a consequence of the process of decoherence. The aim of this paper is to present a new approach to decoherence, different from the mainstream approach of Zurek and his collaborators. We will argue that this approach offers conceptual advantages over the traditional one when problems of foundations are considered; in particular, from the new perspective, decoherence in closed quantum systems becomes possible and the preferred basis acquires a well founded definition.  相似文献   

13.
由于网络化软件的规模和复杂程度的不断增加,设计可伸缩的软件体系结构,开发可演化的软件系统遇到了挑战.挑战之一是很难把软件模型与原系统说明区分开来,使得软件系统的可演化性受到限制.一个有效的途径是建立可范用软件体系结构的抽象模型,指导网构软件设计,从而提高软件模型的概括能力和可伸缩能力.本文提出一种网构软件体系结构代数模型,其中一个创新思想是把网构连接子解释成网构变量的运算.结合代数学方法和软件实现技术,定义了6种网构连接运算,所有运算是对连接子的代数抽象,因此软件体系结构的抽象表达能力得到了加强.为了展示提出代数模型的建模与分析辅助作用,介绍了一个基于代数模型的网构软件设计与演化的案例研究.  相似文献   

14.
本文介绍了一种热电制冷的液冷源系统组成及其设计过程,阐述了应用热电制冷在小功率液冷源系统的设计思路。其控制精度高、可靠性高、体积小、重量轻等优点,使其具有一定的实用价值和推广意义。  相似文献   

15.
Recent progress in understanding the neuro-pathological mechanisms of sleeping sickness reveals a complex relationship between the trypanosome parasite that causes this disease and the host nervous system. The pathology of late-stage sleeping sickness, in which the central nervous system is involved, is complicated and is associated with disturbances in the circadian rhythm of sleep. The blood-brain barrier, which separates circulating blood from the central nervous system, regulates the flow of materials to and from the brain. During the course of disease, the integrity of the blood-brain barrier is compromised. Dysfunction of the nervous system may be exacerbated by factors of trypanosomal origin or by host responses to parasites. Microscopic examination of cerebrospinal fluid remains the best way to confirm late-stage sleeping sickness, but this necessitates a risky lumbar puncture. Most drugs, including many trypanocides, do not cross the blood-brain barrier efficiently. Improved diagnostic and therapeutic approaches are thus urgently required. The latter might benefit from approaches which manipulate the blood-brain barrier to enhance permeability or to limit drug efflux. This review summarizes our current understanding of the neurological aspects of sleeping sickness, and envisages new research into blood-brain barrier models that are necessary to understand the interactions between trypanosomes and drugs active against them within the host nervous system. Received 10 October 2001; received after revision 29 November 2001; accepted 5 December 2001  相似文献   

16.
看门的狗技术是计算机控制系统抗干扰设计的一个主要措施。本文分析了在实际应用中看门狗存在的自身失效问题和由于看门狗复位对微机系统的影响问题,探讨了问题发生的机理并提出了相应的解决方案。实例证明本文提出的措施可有效增强微机控制系统的运行稳定性。  相似文献   

17.
The innate immune system recognizes deviation from homeostasis caused by infectious or non-infectious assaults. The threshold for its activation seems to be established by a calibration process that includes sensing of microbial molecular patterns from commensal bacteria and of endogenous signals. It is becoming increasingly clear that adaptive features, a hallmark of the adaptive immune system, can also be identified in the innate immune system. Such adaptations can result in the manifestation of a primed state of immune and tissue cells with a decreased activation threshold. This keeps the system poised to react quickly. Moreover, the fact that the innate immune system recognizes a wide variety of danger signals via pattern recognition receptors that often activate the same signaling pathways allows for heterologous innate immune stimulation. This implies that, for example, the innate immune response to an infection can be modified by co-infections or other innate stimuli. This “design feature” of the innate immune system has many implications for our understanding of individual susceptibility to diseases or responsiveness to therapies and vaccinations. In this article, adaptive features of the innate immune system as well as heterologous innate immunity and their implications are discussed.  相似文献   

18.
本文提出了一种基于DM642的网络视频服务器设计。系统以DM642为核心实现了视频数据的采集、本地显示、H.264编码和网络传输。介绍了系统的硬件结构和软件设计,重点给出了各个模块的程序设计。实验结果表明,该系统能够满足网络视频服务器实时性和稳定性的要求,具有良好的推广应用价值。  相似文献   

19.
An Erratum has been published for this article in Journal of Forecasting 23(6): 461 (2004) . This paper examines the problem of intrusion in computer systems that causes major breaches or allows unauthorized information manipulation. A new intrusion‐detection system using Bayesian multivariate regression is proposed to predict such unauthorized invasions before they occur and to take further action. We develop and use a multivariate dynamic linear model based on a unique approach leaving the unknown observational variance matrix distribution unspecified. The result is simultaneous forecasting free of the Wishart limitations that is proved faster and more reliable. Our proposed system uses software agent technology. The distributed software agent environment places an agent in each of the computer system workstations. The agent environment creates a user profile for each user. Every user has his or her profile monitored by the agent system and according to our statistical model prediction is possible. Implementation aspects are discussed using real data and an assessment of the model is provided. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

20.
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