The adaptive significance of sexuality

Summary A theory of sexuality and polymorphism is proposed in which diversity at the molecular level is the adaptive response of multicellular organisms to the challenge of microparasites that have smaller genomes, shorter generation times and which can evolve more quickly than their hosts. The theory has implications for genetically homogenized crops and other cultivated plants as well as for immunology. A different function of sexuality is proposed for microorganisms that reproduce both asexually and sexually. Several possible experimental tests are discussed. Mathematical modelling techniques are outlined qualitatively and compared with game-theoretical methods which may be interpreted as simplifications of population dynamic and genetic equilibria. Some results about equilibria, stability and extinction in the population dynamics of polymorphic host-parasite populations are referenced.     

基于结构元方法的矿井机械模糊可靠性分析

应用模糊结构元理论,对矿井可修复机械设备可靠性中的有效度进行研究.首先,定义了模糊可靠度、模糊维修度和模糊有效度,并应用结构元理论对其进行表示.提出了相关的运算定理,在此基础上,再运用结构元理论对模糊有效度进行表示.之后,提出了正序,该序为全序.最后,用算例计算模糊有效度,通过正序对有效度进行比较.结果表明,运用模糊有...     

牵引供电SCADA系统故障树分析研究

应用灰门故障树分析方法对牵引供电SCADA系统的可靠性进行了研究。简要介绍了灰门故障树分析方法的基本理论和牵引供电SCADA系统的基本结构;建立了牵引供电SCADA系统的故障树;用概率灰数描述部件的故障概率,用灰门代替传统逻辑门来描述部件间的联系,用故障测度描述部件的故障程度。对所建立的故障树进行了定量的计算。结果表明,应用灰门故障树分析方法的计算结果是可行有效的。     

大气折射的研究进展

介绍了近几年大气折射映射函数研究的进展、以及几个常用的映射函数。对如今广泛地应用在空间测量技术中的几种映射函数做出评述。讨论了目前在无线电波段中广泛使用的NMF模型的优点和不足之处,提出了改进方向。列出了近几年上海天文台发展的大气折射母函数方法,以及由此导出的大气折射解析解;并分析了大气折射母函数方法引出的大气延迟新连分式映射函数,以及天文大气折射的映射函数方法的优点;指出了光学波段测距精度改进的途径。结合探空气球资料,讨论了大气模式对大气折射计算的影响。     

Subjectivity and emotion in scientific research

A persistent puzzle for philosophers of science is the well-documented appeal made by scientists to their aesthetic emotions in the course of scientific research. Emotions are usually viewed as irremediably subjective, and thus of no epistemological interest. Yet, by denying an epistemic role for scientists’ emotional dispositions, philosophers find themselves in the awkward position of ignoring phenomena which scientists themselves often insist are of importance. This paper suggests a possible solution to this puzzle by challenging the wholesale identification of emotion with subjectivity. The proposed method is a naturalistic and externalist one, calling for empirical investigation into the intersubjective processes by which scientists’ emotional dispositions become refined and attuned to specific objects of attention. The proposal is developed through a critical discussion of Michael Polanyi’s theory of scientific passions, as well as plant geneticist Barbara McClintock’s celebrated “feeling for the organism.”     

Seeking representations of phenomena: Phenomenological models

A distinction is made between theory-driven and phenomenological models. It is argued that phenomenological models are significant means by which theory is applied to phenomena. They act both as sources of knowledge of their target systems and are explanatory of the behaviors of the latter. A version of the shell-model of nuclear structure is analyzed and it is explained why such a model cannot be understood as being subsumed under the theory structure of Quantum Mechanics. Thus its representational capacity does not stem from its close link to theory. It is shown that the shell model yields knowledge about the target and is explanatory of certain behaviors of nuclei. Aspects of the process by which the shell model acquires its representational capacity are analyzed. It is argued that these point to the conclusion that the representational status of the model is a function of its capacity to function as a source of knowledge and its capacity to postulate and explain underlying mechanisms that give rise to the observed behavior of its target.     

MIMO-OFDM系统中基于变分Bayes EM算法的联合符号检测与鲁棒Kalman信道跟踪

基于变分Bayes期望最大化VBEM(variational Bsayes expectation maximization)算法和Turbo原理,提出了快时变信道条件下MIMO-OFDM系统中的联合符号检测与信道估计算法.在VBEM框架下,信号检测和信道估计分别由修正的列表球形译码算法和软输入Kalman算法完成,检测器和估计器分别考虑了信道和检测信号的估计误差协方差矩阵.当信道时变剧烈时,存在较大检测误差的数据在软输入Kalman算法中引入异常值(outliers),由于Kalman算法对于异常值的敏感性,系统会在错误传播的影响下出现误码平台.为削弱异常值的影响,利用鲁棒统计理论设计了VBEM框架下改进的鲁棒软输入Kalman算法,该算法能在出现异常值的条件下保持较好的信道跟踪能力.仿真结果表明:在快速时变多径信道条件下,文中设计的鲁棒VBEM算法优于传统的VBEM算法和EM算法.     

Novelty,coherence, and Mendeleev’s periodic table

Predictivism is the view that successful predictions of “novel” evidence carry more confirmational weight than accommodations of already known evidence. Novelty, in this context, has traditionally been conceived of as temporal novelty. However temporal predictivism has been criticized for lacking a rationale: why should the time order of theory and evidence matter? Instead, it has been proposed, novelty should be construed in terms of use-novelty, according to which evidence is novel if it was not used in the construction of a theory. Only if evidence is use-novel can it fully support the theory entailing it. As I point out in this paper, the writings of the most influential proponent of use-novelty contain a weaker and a stronger version of use-novelty. However both versions, I argue, are problematic. With regard to the appraisal of Mendeleev’ periodic table, the most contentious historical case in the predictivism debate, I argue that temporal predictivism is indeed supported, although in ways not previously appreciated. On the basis of this case, I argue for a form of so-called symptomatic predictivism according to which temporally novel predictions carry more confirmational weight only insofar as they reveal the theory’s presumed coherence of facts as real.     

基于平均增益模型的连续型(1+1)进化算法计算时间复杂性分析

连续型进化算法的计算时间复杂性分析是进化计算理论研究的一项公开难题,目前相关研究成果较少.针对连续型(1+1)EA,基于适应值差函数提出了平均增益模型及其分析方法,给出了平均计算时间的计算理论,为算法的计算时间复杂性分析提供了依据.在此基础上,研究还选取了学术界关注的球形函数作为研究对象,分别推导了变异步长满足标准正态分布和均匀分布的连续型(1+1)EA在优化球形函数时的平均增益,并估算出了它们的平均计算时间.理论分析说明:1)两种算法的计算时间复杂性都是指数级的;2)在给定相同精度和初始适应值差的前提下,采用均匀分布变异算子的算法其寻优速度优于采用标准正态分布变异算子的算法.进一步地,通过数值实验对理论分析结果进行了验证,结果表明平均增益模型分析是有效的.     

One hundred years of Weyl’s (unfinished) unified field theory

In 1918, H. Weyl proposed a unified theory of gravity and electromagnetism based on a generalization of Riemannian geometry. In spite of its elegance and beauty, a serious objection was raised by Einstein, who argued that Weyl’s theory was not suitable as a physical theory . According to Einstein, the theory led to the prediction of a “second clock effect”, which has not been observed by experiments as yet. We briefly revisit this point and argue that a preliminary discussion on the very notion of proper time is needed in order to consider Einstein’s critical point of view. We also point out that Weyl theory is basically incomplete in its original version and its completion may lead to a rich and interesting new approach to gravity.     

煤矿瓦斯事故致因分析及模型构建

统计我国2008年煤矿安全事故原因,说明煤矿瓦斯事故是造成人员伤亡和财产损失的重大原因。分析煤矿瓦斯事故的发生机理,给出其特点及演化规律,从概率的角度阐述瓦斯事故高发的原因。据此构建煤矿瓦斯事故致因理论模型,并提出防范煤矿瓦斯事故再次发生的有效对策和措施,为煤矿安全管理和决策提供重要依据。     

基于特征的矢量场自适应纹理绘制

针对3D流场纹理可视化方法面临的遮挡问题,提出了一种基于流场特征模糊提取的自适应稀疏纹理绘制方法.该方法建立在一种可扩展的模糊流场特征区域描述与提取算法基础上,首先通过采用模糊理论对流场特征区域进行描述,建立了流场特征的测度规则并得到相应特征向量,然后基于特征向量偏差给出了最小平方和误差准则下的模糊测度隶属度的确定方法.根据得到的流场特征模糊隶属度场,生成可突出流场特征信息的自适应高斯噪声以进行纹理LIC卷积.同时针对纹理方法难以明确表示3D流场具体方向的缺陷,提出了两种冷暖光照方法,通过在LIC卷积过程中采用冷暖光照方法突出流场具体方向显示,有效解决了该问题.实验表明,本文方法相对于传统特征提取方法更具有可扩展性.同时自适应技术的采用,有效缓解了3D流场可视化存在的遮挡和混淆现象.而冷暖光照处理的加入,则解决了纹理方法对流场具体方向表现上的缺陷.     

Probability in GRW theory

GRW theory postulates a stochastic mechanism assuring that every so often the wave function of a quantum system is ‘hit’, which leaves it in a localised state. How are we to interpret the probabilities built into this mechanism? GRW theory is a firmly realist proposal and it is therefore clear that these probabilities are objective probabilities (i.e. chances). A discussion of the major theories of chance leads us to the conclusion that GRW probabilities can be understood only as either single case propensities or Humean objective chances. Although single case propensities have some intuitive appeal in the context of GRW theory, on balance it seems that Humean objective chances are preferable on conceptual grounds.     

具有通信受限的网络控制系统量化反馈控制

针对一类通信受限的网络控制系统,研究量化反馈控制器及动态调度策略的联合设计问题.考虑到介质访问约束和信号量化误差的影响,将网络控制系统建模为等价的离散时间切换系统;通过Lyapunov稳定理论推导出保证系统鲁棒稳定的模式及量化依赖型充分条件,并给出了量化反馈控制器的设计方法;在此基础上,设计了基于实时状态的动态通信调度策略,实现了网络控制系统的镇定控制.最后通过仿真示例验证了所提出方法的有效性.     

Holism, physical theories and quantum mechanics

Motivated by the question what it is that makes quantum mechanics a holistic theory (if so), I try to define for general physical theories what we mean by `holism'. For this purpose I propose an epistemological criterion to decide whether or not a physical theory is holistic, namely: a physical theory is holistic if and only if it is impossible in principle to infer the global properties, as assigned in the theory, by local resources available to an agent. I propose that these resources include at least all local operations and classical communication. This approach is contrasted with the well-known approaches to holism in terms of supervenience. The criterion for holism proposed here involves a shift in emphasis from ontology to epistemology. I apply this epistemological criterion to classical physics and Bohmian mechanics as represented on a phase and configuration space respectively, and for quantum mechanics (in the orthodox interpretation) using the formalism of general quantum operations as completely positive trace non-increasing maps. Furthermore, I provide an interesting example from which one can conclude that quantum mechanics is holistic in the above mentioned sense, although, perhaps surprisingly, no entanglement is needed.     

Emergence in holographic scenarios for gravity

‘Holographic’ relations between theories have become an important theme in quantum gravity research. These relations entail that a theory without gravity is equivalent to a gravitational theory with an extra spatial dimension. The idea of holography was first proposed in 1993 by Gerard ׳t Hooft on the basis of his studies of evaporating black holes. Soon afterwards the holographic ‘AdS/CFT’ duality was introduced, which since has been intensively studied in the string theory community and beyond. Recently, Erik Verlinde has proposed that even Newton׳s law of gravitation can be related holographically to the ‘thermodynamics of information’ on screens. We discuss these scenarios, with special attention to the status of the holographic relation in them and to the question of whether they make gravity and spacetime emergent. We conclude that only Verlinde׳s scheme straightforwardly instantiates emergence. However, assuming a non-standard interpretation of AdS/CFT may create room for the emergence of spacetime and gravity there as well.     

农田渍害遥感监测方法研究应用进展

首先介绍了农田渍害的表现特征;其次根据监测原理,将国内外农田溃害遥感监测的主要方法分为地表指示标志法、地下水位反演法和与非遥感方法相结合的综合分析法,并分别对各类方法的原理、技术、适用范围及优缺点进行分析,发现各种方法均能解决特定的农田渍害监测问题,同时也存在着缺陷和局限性;最后,进行了总结并指出了两种潜在的遥感监测方...     

Arguing against fundamentality

This paper aims to open up discussion on the relationship between fundamentality and naturalism, and in particular on the question of whether fundamentality may be denied on naturalistic grounds. A historico-inductive argument for an anti-fundamentalist conclusion, prominent within the contemporary metaphysical literature, is examined; finding it wanting, an alternative ‘internal’ strategy is proposed. By means of an example from the history of modern physics – namely S-matrix theory – it is demonstrated that (1) this strategy can generate similar (though not identical) anti-fundamentalist conclusions on more defensible naturalistic grounds, and (2) that fundamentality questions can be empirical questions. Some implications and limitations of the proposed approach are discussed.