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In this work, we first consider the discrete version of Fisher information measure and then propose Jensen–Fisher information, to develop some associated results. Next, we consider Fisher information and Bayes–Fisher information measures for mixing parameter vector of a finite mixture probability mass function and establish some results. We provide some connections between these measures with some known informational measures such as chi-square divergence, Shannon entropy, Kullback–Leibler, Jeffreys and Jensen–Shannon divergences. 相似文献
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对光学系统MTF测试中采样窗口对其测量影响进行了研究。在对标准镜头MTF测试时,采用离散傅里叶变换计算,线扩散函数扫描方向长度为所选针孔像线扩散函数半高宽的5倍左右时,MTF测试结果与设计值差异极值为0.011;采用快速傅里叶变换计算,线扩散函数扫描方向长度为所选针孔像线扩散函数半高宽的5倍左右时,同时采样点数要满足2^N,测试结果与设计值差异极值为0.010。为了证明此结论的普适性,按所提的采样窗口选取原则,对大像差镜头轴上和轴外的MTF进行了试验,并将测试结果与OPTIKOS的测试结果进行对比,最大极差为0.013。试验结果表明,此结论能够为光学系统MTF测试时采样窗口选择提供依据。 相似文献
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电磁波在多层介质内的透射 总被引:5,自引:0,他引:5
导了多层介质中透射电磁波的电场振幅与介质表面入射电磁波场电场振幅之间的关系式,引入了一个母函数,通过微分可以生成介质各层中的透射波。 相似文献
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In this research paper, we propose a two-hop integrated radio frequency–visible light communication (RF–VLC) system which may provide a better option to transceive between the hospitals and some laboratory to transfer patient’s information. In the proposed system model, the data (such as patient’s lab test reports) is transmitted towards the amplify and forward (AF) relay mounted on the top of the hospital building via the RF channel. Further, the AF relay amplifies and converts the received information into corresponding optical signal using light emitting diodes (LED) and supporting circuitry. This optical signal is then forwarded towards the destination device (equipped with VLC transceiver), via the VLC channel. To analyse the performance of the system, we first derive the closed form analytical expressions for the cumulative distribution function (CDF) of the end-to-end (e2e) signal to noise ratio (SNR) of the system by using the moment generating function (MGF) of the SNR of the individual RF and VLC channels. Further, we use these statistical expressions to obtain the outage probability, average bit error rate (BER) and the average capacity of the system. Moreover, the asymptotic performance of the proposed system is also analysed to study the system’s behaviour at high SNR regimes. Finally, we studied the impact of the variations in channel parameters on the proposed system model performance through numerically simulated plots. 相似文献
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Chenguang Lu 《Entropy (Basel, Switzerland)》2021,23(8)
In the rate-distortion function and the Maximum Entropy (ME) method, Minimum Mutual Information (MMI) distributions and ME distributions are expressed by Bayes-like formulas, including Negative Exponential Functions (NEFs) and partition functions. Why do these non-probability functions exist in Bayes-like formulas? On the other hand, the rate-distortion function has three disadvantages: (1) the distortion function is subjectively defined; (2) the definition of the distortion function between instances and labels is often difficult; (3) it cannot be used for data compression according to the labels’ semantic meanings. The author has proposed using the semantic information G measure with both statistical probability and logical probability before. We can now explain NEFs as truth functions, partition functions as logical probabilities, Bayes-like formulas as semantic Bayes’ formulas, MMI as Semantic Mutual Information (SMI), and ME as extreme ME minus SMI. In overcoming the above disadvantages, this paper sets up the relationship between truth functions and distortion functions, obtains truth functions from samples by machine learning, and constructs constraint conditions with truth functions to extend rate-distortion functions. Two examples are used to help readers understand the MMI iteration and to support the theoretical results. Using truth functions and the semantic information G measure, we can combine machine learning and data compression, including semantic compression. We need further studies to explore general data compression and recovery, according to the semantic meaning. 相似文献
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光衍射数值模拟中不同抽样方法的适用性分析 总被引:5,自引:2,他引:3
基于标量衍射理论和快速傅里叶变换,分析了光衍射的数值模拟时可以采用的不同抽样方法及其适用性。理论分析表明,按照抽样对象的不同,存在三种适用范围不同的算法:传递函数抽样法、点扩展函数抽样法和加权函数抽样法。其适用范围分别为衍射距离小于、大于和等于特征距离的情况。在Matlab软件环境下给出了三种算法的模拟计算实例,并与相应的实验结果进行了比较,证明了理论分析的正确性。最后还给出了一种无需改变抽样点数和抽样间隔就可计算任意距离衍射过程的自适应抽样算法及其在数字全息再现中的应用实例。 相似文献
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In nonrigid image registration, similarity measures including spatial information have been shown to perform better than those measures without spatial information. In this work, we provide new insight to the relationships among regional mutual information, regional probability distribution functions (PDFs) and global PDFs, and propose a novel nonrigid registration scheme with spatially weighted global probability distribution function (SWGPDF). Similarity measures based on SWGPDF (SWGPDFSM) are constructed. Three different spatial sub-region division methods are compared: the equally spaced sub-region (ESSR), the local binary pattern sub-region (LBPSR) and the gradient sub-region (GSR). The registration scheme applies B-spline based free form deformations (FFDs) as the transformation model. A Parzen window and linear interpolation are used to construct histograms. The SWGPDFSM registration scheme with ESSR space division is compared with the traditional global mutual information (gMI), the traditional global normalized mutual information (gNMI), regional mutual information and the SWGPDFSM with LBPSR or GSR space division. The test results show that SWGPDFSM scheme with ESSR space division outperforms the other schemes for elastically aligning images in the presence of big geometrical transformations, bias fields and illumination changes. 相似文献
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N. Ay N. Bertschinger R. Der F. Güttler E. Olbrich 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(3):329-339
Measures of complexity are of immediate interest for the field of autonomous
robots both as a means to classify the behavior and as an objective function
for the autonomous development of robot behavior. In the present paper we
consider predictive information in sensor space as a measure for the
behavioral complexity of a two-wheel embodied robot moving in a rectangular
arena with several obstacles. The mutual information (MI) between past and
future sensor values is found empirically to have a maximum for a behavior
which is both explorative and sensitive to the environment. This makes
predictive information a prospective candidate as an objective function for
the autonomous development of such behaviors. We derive theoretical
expressions for the MI in order to obtain an explicit update rule for the
gradient ascent dynamics. Interestingly, in the case of a linear or
linearized model of the sensorimotor dynamics the structure of the learning
rule derived depends only on the dynamical properties while the value of the
MI influences only the learning rate. In this way the problem of the
prohibitively large sampling times for information theoretic measures can be
circumvented. This result can be generalized and may help to derive explicit
learning rules from complexity theoretic measures. 相似文献
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A universal symplectic structure for a Newtonian system including
nonconservative cases can be constructed in the framework of Birkhoffian
generalization of Hamiltonian mechanics. In this paper the symplectic
geometry structure of Birkhoffian system is discussed, then the
symplecticity of Birkhoffian phase flow is presented. Based on these
properties we give a way to construct symplectic schemes for Birkhoffian
systems by using the generating function method. 相似文献
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G Ananthakrishna 《Pramana》1979,12(5):543-561
The model introduced for clustering of quenched-in vacancies in the first part of this series of papers is considered. Using
a generating function, the rate equations are converted into a first order partial differential equation for the generating
function coupled to a differential equation for the rate of change of the concentration of single vacancy units. A decoupling
scheme is effected which gives an exponentially decaying solution with a very short time constant for the concentration of
single vacancy units. The differential equation for the generating function is solved for times larger than the time required
for the concentration of single vacancy units to reach its asymptotic value. The distribution for the size of the clusters
is obtained by inverting the solution thus obtained. Several results that follow are shown to be in reasonably good agreement
with the experimental results. 相似文献
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Makoto Oonuki 《Journal of statistical physics》1972,6(2-3):119-131
The time characteristics of a linear network in the brain are obtained by the method of the time partition function, which is analogous to a grand partition function or a distribution function in statistical mechanics. The analogy between the average density in a many-particle system and the reciprocal of the frequency in a network is shown. By this method, the frequency distribution functions are obtained with respect to a network composed of two layers, the network used in information retrieval and the network generating a brain wave. 相似文献
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Sangun Park 《Entropy (Basel, Switzerland)》2021,23(3)
It is well-known that some information measures, including Fisher information and entropy, can be represented in terms of the hazard function. In this paper, we provide the representations of more information measures, including quantal Fisher information and quantal Kullback-leibler information, in terms of the hazard function and reverse hazard function. We provide some estimators of the quantal KL information, which include the Anderson-Darling test statistic, and compare their performances. 相似文献
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应用一维Vlasov和Maxwell耦合程序详细研究了激光等离子体相互作用中的基本问题——受激拉曼散射(SRS). 通过研究发现, SRS的产生与电子速度分布函数在相空间中的结构密切相关, 当电子速度分布函数形成相空间涡旋时,背向SRS光大幅增加,而当电子等离子体波相速度附近的电子速度分布函数曲线变平坦后, 背向SRS光基本停止发生. 在模拟中观测到了SRS的爆发、电子速度分布函数形成相空间涡旋、电子俘获等清晰的物理图像.
关键词:
Vlasov-Maxwell模拟
受激拉曼散射 相似文献
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The path-integral quantization of thermal scalar, vector, and spinor fields is performed newly in the coherent-state representation. In doing this, we choose the thermal electrodynamics and φ4 theory as examples. By
this quantization, correct expressions of the partition functions and the
generating functionals for the quantum thermal electrodynamics and
φ4 theory are obtained in the coherent-state representation. These
expressions allow us to perform analytical calculations of the partition
functions and generating functionals and therefore are useful in practical
applications. Especially, the perturbative expansions of the generating functionals are derived specifically by virtue of the stationary-phase
method. The generating functionals formulated in the position space are
re-derived from the ones given in the coherent-state representation. 相似文献
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Radial imaging techniques, such as projection-reconstruction (PR), are used in magnetic resonance imaging (MRI) for dynamic imaging, angiography, and short-T2 imaging. They are less sensitive to flow and motion artifacts, and support fast imaging with short echo times. However, aliasing and streaking artifacts are two main sources which degrade radial imaging quality. For a given fixed number of k-space projections, data distributions along radial and angular directions will influence the level of aliasing and streaking artifacts. Conventional radial k-space sampling trajectory introduces an aliasing artifact at the first principal ring of point spread function (PSF). In this paper, a shaking projection (SP) k-space sampling trajectory was proposed to reduce aliasing artifacts in MR images. SP sampling trajectory shifts the projection alternately along the k-space center, which separates k-space data in the azimuthal direction. Simulations based on conventional and SP sampling trajectories were compared with the same number projections. A significant reduction of aliasing artifacts was observed using the SP sampling trajectory. These two trajectories were also compared with different sampling frequencies. ASP trajectory has the same aliasing character when using half sampling frequency (or half data) for reconstruction. SNR comparisons with different white noise levels show that these two trajectories have the same SNR character. In conclusion, the SP trajectory can reduce the aliasing artifact without decreasing SNR and also provide a way for undersampling recon- struction. Furthermore, this method can be applied to three-dimensional (3D) hybrid or spherical radial k-space sampling for a more efficient reduction of aliasing artifacts. 相似文献