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DDoS Attack Detection Scheme Based on Entropy and PSO-BP Neural Network in SDN 被引量:8
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作者 Zhenpeng Liu Yupeng He +1 位作者 Wensheng Wang Bin Zhang 《China Communications》 SCIE CSCD 2019年第7期144-155,共12页
SDN (Software Defined Network) has many security problems, and DDoS attack is undoubtedly the most serious harm to SDN architecture network. How to accurately and effectively detect DDoS attacks has always been a diff... SDN (Software Defined Network) has many security problems, and DDoS attack is undoubtedly the most serious harm to SDN architecture network. How to accurately and effectively detect DDoS attacks has always been a difficult point and focus of SDN security research. Based on the characteristics of SDN, a DDoS attack detection method combining generalized entropy and PSOBP neural network is proposed. The traffic is pre-detected by the generalized entropy method deployed on the switch, and the detection result is divided into normal and abnormal. Locate the switch that issued the abnormal alarm. The controller uses the PSO-BP neural network to detect whether a DDoS attack occurs by further extracting the flow features of the abnormal switch. Experiments show that compared with other methods, the detection accurate rate is guaranteed while the CPU load of the controller is reduced, and the detection capability is better. 展开更多
关键词 software-defined NETWORKING distributed DENIAL of service ATTACKS generalized information entropy particle SWARM optimization back propagation neural network ATTACK detection
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Existence of Entropy Solution for Degenerate Parabolic-Hyperbolic Problem Involving p(x)-Laplacian with Neumann Boundary Condition
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作者 Mohamed Karimou Gazibo Duni Yegbonoma Frédéric Zongo 《Applied Mathematics》 2024年第7期455-463,共9页
We consider a strongly non-linear degenerate parabolic-hyperbolic problem with p(x)-Laplacian diffusion flux function. We propose an entropy formulation and prove the existence of an entropy solution.
关键词 Lebesgue and Sobolev Spaces with Variable Exponent Weak Solution entropy Solution Degenerate Parabolic-Hyperbolic Equation Conservation Law Leray Lions Type Operator Neumann Boundary Condition Existence Result
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Dense Fractal Networks, Trends, Noises and Switches in Homeostasis Regulation of Shannon Entropy for Chromosomes’ Activity in Living Cells for Medical Diagnostics
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作者 Nikolay E. Galich 《Applied Mathematics》 2013年第11期30-41,共12页
We analyze correlations and patterns of oxidative activity of 3D DNA at DNA fluorescence in complete sets of chromosomes in neutrophils of peripheral blood. Fluorescence of DNA is registered by method of flow cytometr... We analyze correlations and patterns of oxidative activity of 3D DNA at DNA fluorescence in complete sets of chromosomes in neutrophils of peripheral blood. Fluorescence of DNA is registered by method of flow cytometry with nanometer spatial resolution. Experimental data present fluorescence of many ten thousands of cells, from different parts of body in each population, in various blood samples. Data is presented in histograms as frequency distributions of flashes in the dependence on their intensity. Normalized frequency distribution of information in these histograms is used as probabilistic measure for definition of Shannon entropy. Data analysis shows that for this measure of Shannon entropy common sum of entropy, i.e. total entropy E, for any histogram is invariant and has identical trends of changes all values of E (r) = lnr at reduction of rank r of histogram. This invariance reflects informational homeostasis of chromosomes activity inside cells in multi-scale networks of entropy, for varied ranks r. Shannon entropy in multi-scale DNA networks has much more dense packing of correlations than in “small world” networks. As the rule, networks of entropy differ by the mix of normal D 2 and abnormal D > 2 fractal dimensions for varied ranks r, the new types of fractal patterns and hinges for various topology (fractal dimension) at different states of health. We show that all distributions of information entropy are divided on three classes, which associated in diagnostics with a good health or dominants of autoimmune or inflammatory diseases. This classification based on switching of stability at transcritical bifurcation in homeostasis regulation. We defined many ways for homeostasis regulation, coincidences and switching patterns in branching sequences, the averages of H&ouml;lder for deviations of entropy from homeostasis at different states of health, with various saturation levels the noises of entropy at activity of all chromosomes in support regulation of homeostasis. 展开更多
关键词 Abnormal Fractals DNA ACTIVITY and Shannon Information entropy FRACTAL Patterns and Fragmentation Informational HOMEOSTASIS Saturations of CHROMOSOMAL Correlations Multi-Scale FRACTAL NETWORKS of Shannon entropy
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基于ENTROPY-TOPSIS算法的电路实验课程综合成绩评定方法
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作者 徐航 孙曼 +2 位作者 印月 王东平 吴海祥 《实验科学与技术》 2024年第2期108-112,共5页
针对高校实践教学成绩评定环节中存在的不足,该文将基于修正ENTROPY-TOPSIS算法应用到实验课程成绩评定当中,并推导了具体算法原理。同时将该算法与常用权值算法层次分析法以及CRITIC算法在电路实践成绩客观赋权过程中进行了横向对比。... 针对高校实践教学成绩评定环节中存在的不足,该文将基于修正ENTROPY-TOPSIS算法应用到实验课程成绩评定当中,并推导了具体算法原理。同时将该算法与常用权值算法层次分析法以及CRITIC算法在电路实践成绩客观赋权过程中进行了横向对比。结果显示该方法可以为多源异构数据的科学赋权提供理论依据,有效消除因主观因素带来的不合理性,使教师在实验成绩的评定上更加趋向于客观化、科学化。 展开更多
关键词 CRITIC entropy算法 TOPSIS
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Equilibrium Energy and Entropy of Vortex Filaments in the Context of Tornadogenesis and Tornadic Flows
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作者 Pavel Bělík Douglas P. Dokken +3 位作者 Mikhail M. Shvartsman Eric Bibelnieks Robert Laskowski Alek Lukanen 《Open Journal of Fluid Dynamics》 2023年第3期144-176,共33页
In this work, we study approximations of supercritical or suction vortices in tornadic flows and their contribution to tornadogenesis and tornado maintenance using self-avoiding walks on a cubic lattice. We extend the... In this work, we study approximations of supercritical or suction vortices in tornadic flows and their contribution to tornadogenesis and tornado maintenance using self-avoiding walks on a cubic lattice. We extend the previous work on turbulence by A. Chorin and collaborators to approximate the statistical equilibrium quantities of vortex filaments on a cubic lattice when both an energy and a statistical temperature are involved. Our results confirm that supercritical (smooth, “straight”) vortices have the highest average energy and correspond to negative temperatures in this model. The lowest-energy configurations are folded up and “balled up” to a great extent. The results support A. Chorin’s findings that, in the context of supercritical vortices in a tornadic flow, when such high-energy vortices stretch, they need to fold and transfer energy to the surrounding flow, contributing to tornado maintenance or leading to its genesis. The computations are performed using a Markov Chain Monte Carlo approach with a simple sampling algorithm using local transformations that allow the results to be reliable over a wide range of statistical temperatures, unlike the originally used pivot algorithm that only performs well near infinite temperatures. Efficient ways to compute entropy are discussed and show that a system with supercritical vortices will increase entropy by having these vortices fold and transfer their energy to the surrounding flow. 展开更多
关键词 Tornadogenesis Supercritical Vortices Vortex Filaments Negative Temperature Kinetic Energy entropy Statistical Mechanics Equilibrium Statistics Self-Avoiding Walks Cubic Lattice Monte-Carlo Techniques Pivot Algorithm
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Construction of Global Weak Entropy Solution of Initial-Boundary Value Problem for Scalar Conservation Laws with Weak Discontinuous Flux
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作者 Yihong Dai Jing Zhang 《American Journal of Computational Mathematics》 2017年第4期451-468,共18页
This paper is concerned with the initial-boundary value problem of scalar conservation laws with weak discontinuous flux, whose initial data are a function with two pieces of constant and whose boundary data are a con... This paper is concerned with the initial-boundary value problem of scalar conservation laws with weak discontinuous flux, whose initial data are a function with two pieces of constant and whose boundary data are a constant function. Under the condition that the flux function has a finite number of weak discontinuous points, by using the structure of weak entropy solution of the corresponding initial value problem and the boundary entropy condition developed by Bardos-Leroux-Nedelec, we give a construction method to the global weak entropy solution for this initial-boundary value problem, and by investigating the interaction of elementary waves and the boundary, we clarify the geometric structure and the behavior of boundary for the weak entropy solution. 展开更多
关键词 Scalar Conservation LAWS with WEAK Discontinuous Flux Initial-Boundary Value Problem ELEMENTARY Wave Interaction Structure of GLOBAL WEAK entropy Solution
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System structural analysis of communication networks based on DEMATEL-ISM and entropy 被引量:2
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作者 FU Kai XIA Jing-bo +1 位作者 ZHANG Xiao-yan SHEN Jian 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第7期1594-1601,共8页
A method of system structural analysis based on decision making trial and evaluation laboratory together with interpretative structural modeling(DEMATEL-ISM) and entropy is proposed to clarify system structure of comm... A method of system structural analysis based on decision making trial and evaluation laboratory together with interpretative structural modeling(DEMATEL-ISM) and entropy is proposed to clarify system structure of communication networks and analyze mutual influencing degree between different networks.Mutual influencing degree and importance degree of elements are both considered to determine weights of elements,and the entropy of expert judgment results is used to omit unimportant influence relation and simplify system structure.Structural analysis on communication networks system shows that the proposed method can quantificationally present weights and mutual influencing degree of elements,and reasonably simplify system structure.The results indicate the rationality and feasibility of the method. 展开更多
关键词 communication NETWORKS SYSTEM STRUCTURAL analysis decision making trial and evaluation laboratory (DEMATEL) interpretative STRUCTURAL modeling (ISM) entropy
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Tree Network Formation in Poisson Equation Models and the Implications for the Maximum Entropy Production Principle
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作者 Hiroshi Serizawa Takashi Amemiya Kiminori Itoh 《Natural Science》 2014年第7期514-527,共14页
This paper presents not only practical but also instructive mathematical models to simulate tree network formation using the Poisson equation and the Finite Difference Method (FDM). Then, the implications for entropic... This paper presents not only practical but also instructive mathematical models to simulate tree network formation using the Poisson equation and the Finite Difference Method (FDM). Then, the implications for entropic theories are discussed from the viewpoint of Maximum Entropy Production (MEP). According to the MEP principle, open systems existing in the state far from equilibrium are stabilized when entropy production is maximized, creating dissipative structures with low entropy such as the tree-shaped network. We prepare two simulation models: one is the Poisson equation model that simulates the state far from equilibrium, and the other is the Laplace equation model that simulates the isolated state or the state near thermodynamic equilibrium. The output of these equations is considered to be positively correlated to entropy production of the system. Setting the Poisson equation model so that entropy production is maximized, tree network formation is advanced. We suppose that this is due to the invocation of the MEP principle, that is, entropy of the system is lowered by emitting maximal entropy out of the system. On the other hand, tree network formation is not observed in the Laplace equation model. Our simulation results will offer the persuasive evidence that certifies the effect of the MEP principle. 展开更多
关键词 DISSIPATIVE Structure Far from Equilibrium Fractal POISSON Equation Maximum entropy PRODUCTION (MEP) PRINCIPLE Minimum entropy PRODUCTION (MinEP) PRINCIPLE Tree Network
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A new approach for epileptic seizure detection: sample entropy based feature extraction and extreme learning machine 被引量:8
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作者 Yuedong Song Pietro Liò 《Journal of Biomedical Science and Engineering》 2010年第6期556-567,共12页
The electroencephalogram (EEG) signal plays a key role in the diagnosis of epilepsy. Substantial data is generated by the EEG recordings of ambulatory recording systems, and detection of epileptic activity requires a ... The electroencephalogram (EEG) signal plays a key role in the diagnosis of epilepsy. Substantial data is generated by the EEG recordings of ambulatory recording systems, and detection of epileptic activity requires a time-consuming analysis of the complete length of the EEG time series data by a neurology expert. A variety of automatic epilepsy detection systems have been developed during the last ten years. In this paper, we investigate the potential of a recently-proposed statistical measure parameter regarded as Sample Entropy (SampEn), as a method of feature extraction to the task of classifying three different kinds of EEG signals (normal, interictal and ictal) and detecting epileptic seizures. It is known that the value of the SampEn falls suddenly during an epileptic seizure and this fact is utilized in the proposed diagnosis system. Two different kinds of classification models, back-propagation neural network (BPNN) and the recently-developed extreme learning machine (ELM) are tested in this study. Results show that the proposed automatic epilepsy detection system which uses sample entropy (SampEn) as the only input feature, together with extreme learning machine (ELM) classification model, not only achieves high classification accuracy (95.67%) but also very fast speed. 展开更多
关键词 Epileptic SEIZURE ELECTROENCEPHALOGRAM (EEG) SAMPLE entropy (SampEn) Backpropagation Neural Network (BPNN) EXTREME Learning Machine (ELM) Detection
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Entropy and Negentropy Principles in the I-Theory 被引量:1
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作者 H. H. Swami Isa Christophe Dumas 《Journal of High Energy Physics, Gravitation and Cosmology》 2020年第2期259-273,共15页
Applying the I-Theory, this paper gives a new outlook about the concept of Entropy and Negentropy. Using S∞ particle as 100% repelling energy and A1 particle as the starting point of attraction, we are able to define... Applying the I-Theory, this paper gives a new outlook about the concept of Entropy and Negentropy. Using S∞ particle as 100% repelling energy and A1 particle as the starting point of attraction, we are able to define Entropy and Negentropy on the quantum level. As the I-Theory explains that repulsion force is driven by Weak Force and attraction is driven by Strong Force, we also analyze Entropy and Negentropy in terms of the Fundamental Forces. 展开更多
关键词 I-Theory I-Particle entropy NEGentropy Syntropy Intelligence Black MATTER White MATTER Red MATTER Gravitation Strong FORCE Weak FORCE Free Energy
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基于ISM-AHP-Entropy航空公司风险因素研究
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作者 罗凤娥 徐勇 +1 位作者 卫昌波 杜裕鑫 《航空计算技术》 2024年第2期26-31,共6页
针对航空公司风险因素研究,引入ISM-AHP-Entropy综合评价方法对风险因素进行评价。构建了风险因素指标体系,利用解析结构模型(ISM)将因素指标分为表层和深层致因,构建结构模型;根据问卷结果,用AHP-Entropy求出综合权重,结果表明人因和... 针对航空公司风险因素研究,引入ISM-AHP-Entropy综合评价方法对风险因素进行评价。构建了风险因素指标体系,利用解析结构模型(ISM)将因素指标分为表层和深层致因,构建结构模型;根据问卷结果,用AHP-Entropy求出综合权重,结果表明人因和管理因素对风险影响最为显著;进一步运用AHP-Entropy综合法分别计算表层和深层致因权重并分析,结果表明表层致因中机组资源管理水平、签派员应急处置能力影响最为显著,深层致因中安全规章方针的制定情况、应急管理培训与实施情况影响最为显著;从多个现实角度出发,结合CBTA理念,为航空公司降低风险、提高安全意识与水平提出多条建议,可供航空公司参考采纳。 展开更多
关键词
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Estimation of the anisotropy of hydraulic conductivity through 3D fracture networks using the directional geological entropy 被引量:1
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作者 Chuangbing Zhou Zuyang Ye +2 位作者 Chi Yao Xincheng Fan Feng Xiong 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2024年第2期137-148,共12页
With an extension of the geological entropy concept in porous media,the approach called directional entrogram is applied to link hydraulic behavior to the anisotropy of the 3D fracture networks.A metric called directi... With an extension of the geological entropy concept in porous media,the approach called directional entrogram is applied to link hydraulic behavior to the anisotropy of the 3D fracture networks.A metric called directional entropic scale is used to measure the anisotropy of spatial order in different directions.Compared with the traditional connectivity indexes based on the statistics of fracture geometry,the directional entropic scale is capable to quantify the anisotropy of connectivity and hydraulic conductivity in heterogeneous 3D fracture networks.According to the numerical analysis of directional entrogram and fluid flow in a number of the 3D fracture networks,the hydraulic conductivities and entropic scales in different directions both increase with spatial order(i.e.,trace length decreasing and spacing increasing)and are independent of the dip angle.As a result,the nonlinear correlation between the hydraulic conductivities and entropic scales from different directions can be unified as quadratic polynomial function,which can shed light on the anisotropic effect of spatial order and global entropy on the heterogeneous hydraulic behaviors. 展开更多
关键词 3D fracture network Geological entropy Directional entropic scale ANISOTROPY Hydraulic conductivity
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Boron-doped high-entropy oxide toward high-rate and long-cycle layered cathodes for wide-temperature sodium-ion batteries 被引量:1
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作者 Yuzhen Dang Zhe Xu +8 位作者 Yurong Wu Runguo Zheng Zhiyuan Wang Xiaopin Lin Yanguo Liu Zheng-Yao Li Kai Sun Dongfeng Chen Dan Wang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第8期577-587,I0012,共12页
03-type layered metal oxides hold great promise for sodium-ion batteries cathodes owing to their energy density advantage.However,the severe irreversible phase transition and sluggish Na^(+)diffusion kinetics pose sig... 03-type layered metal oxides hold great promise for sodium-ion batteries cathodes owing to their energy density advantage.However,the severe irreversible phase transition and sluggish Na^(+)diffusion kinetics pose significant challenges to achieve high-performance layered cathodes.Herein,a boron-doped03-type high entropy oxide Na(Fe_(0.2)Co_(0.15)Cu_(0.05)Ni_(0.2)Mn_(0.2)Ti_(0.2))B_(0.02)O_(2)(NFCCNMT-B_(0.02))is designed and the covalent B-O bonds with high entropy configuration ensure a robust layered structure.The obtained cathode NFCCNMT-B_(0.02)exhibits impressive cycling performance(capacity retention of 95%and 82%after100 cycles and 300 cycles at 1 and 10 C,respectively)and outstanding rate capability(capacity of 83 mAh g^(-1)at 10 C).Furthermore,the NFCCNMT-B_(0.02)demonstrates a superior wide-temperature performance,maintaining the same capacity level(113,4 mAh g^(-1)@-20℃,121 mAh g^(-1)@25℃,and 119 mAh g^(-1)@60℃)and superior cycle stability(90%capacity retention after 100 cycles at 1 C at-20℃).The high-entropy configuration design with boron doping strategy contributes to the excellent sodium-ion storage performance.The high-entropy configuration design effectively suppresses irreversible phase transitions accompanied by small volume changes(ΔV=0.65 A3).B ions doping expands the Na layer distance and enlarges the P3 phase region,thereby enhancing Na^(+)diffusion kinetics.This work offers valuable insights into design of high-performance layered cathodes for sodium-ion batteries operating across a wide temperature. 展开更多
关键词 High entropy oxide Born substitution Phase transition Na~%PLUS%diffusion kinetics Sodium-ion batteries
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基于信息熵和集对理论的堤防工程安全评价 被引量:7
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作者 刘亚莲 胡建平 周翠英 《水电能源科学》 北大核心 2010年第10期96-98,73,共4页
针对堤防工程为防洪体系的重要组成部分,将信息熵与模糊集对分析理论相耦合,构建了基于熵权的模糊集对分析安全评价模型,以广东省北江大堤为例,计算了各评价指标的熵权,并集对分析了样本各指标的同一、差异、对立,根据计算的联系度按集... 针对堤防工程为防洪体系的重要组成部分,将信息熵与模糊集对分析理论相耦合,构建了基于熵权的模糊集对分析安全评价模型,以广东省北江大堤为例,计算了各评价指标的熵权,并集对分析了样本各指标的同一、差异、对立,根据计算的联系度按集对分析评价原则安全评价了各样本,为堤防工程安全评价提供了新途径。 展开更多
关键词 Set Pair Analysis Information entropy Based 广
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Detection method of forward-scatter signal based on Rényi entropy 被引量:1
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作者 ZHENG Yuqing AI Xiaofeng +2 位作者 YANG Yong ZHAO Feng XIAO Shunping 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第4期865-873,共9页
The application scope of the forward scatter radar(FSR)based on the Global Navigation Satellite System(GNSS)can be expanded by improving the detection capability.Firstly,the forward-scatter signal model when the targe... The application scope of the forward scatter radar(FSR)based on the Global Navigation Satellite System(GNSS)can be expanded by improving the detection capability.Firstly,the forward-scatter signal model when the target crosses the baseline is constructed.Then,the detection method of the for-ward-scatter signal based on the Rényi entropy of time-fre-quency distribution is proposed and the detection performance with different time-frequency distributions is compared.Simula-tion results show that the method based on the smooth pseudo Wigner-Ville distribution(SPWVD)can achieve the best perfor-mance.Next,combined with the geometry of FSR,the influence on detection performance of the relative distance between the target and the baseline is analyzed.Finally,the proposed method is validated by the anechoic chamber measurements and the results show that the detection ability has a 10 dB improvement compared with the common constant false alarm rate(CFAR)detection. 展开更多
关键词 forward scatter radar(FSR) Global Navigation Satellite System(GNSS) time-frequency distribution Rényi entropy signal detection
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Flat Space Cosmology as a Model of Penrose’s Weyl Curvature Hypothesis and Gravitational Entropy
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作者 Eugene Terry Tatum 《Journal of Modern Physics》 2018年第10期1935-1940,共6页
FSC is shown to be an excellent model of Penrose’s Weyl curvature hypothesis and his concept of gravitational entropy. The assumptions of FSC allow for the minimum entropy at the inception of the cosmic expansion and... FSC is shown to be an excellent model of Penrose’s Weyl curvature hypothesis and his concept of gravitational entropy. The assumptions of FSC allow for the minimum entropy at the inception of the cosmic expansion and rigorously define a cosmological arrow of time. This is in sharp contrast to inflationary models, which appear to violate the second law of thermodynamics within the early universe. Furthermore, by virtue of the same physical assumptions applying at any cosmic time t, the perpetually-flat FSC model predicts the degree of scale invariance observed in the CMB anisotropy pattern, without requiring an explosive and exceedingly brief inflationary epoch. Penrose’s concepts, as described in this paper, provide support for the idea that FSC models gravitational entropy and Verlinde’s emergent gravity theory. 展开更多
关键词 FLAT Space COSMOLOGY COSMOLOGY Theory GRAVITATIONAL entropy Weyls Curvature HYPOTHESIS Black Holes COSMIC Inflation COSMIC Flatness COSMIC Microwave Background
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Exploring Biocomplexity in Cancer: A Comprehensive Review
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作者 Andras Szasz Gyula Peter Szigeti 《Open Journal of Biophysics》 2024年第2期154-238,共85页
Living objects have complex internal and external interactions. The complexity is regulated and controlled by homeostasis, which is the balance of multiple opposing influences. The environmental effects finally guide ... Living objects have complex internal and external interactions. The complexity is regulated and controlled by homeostasis, which is the balance of multiple opposing influences. The environmental effects finally guide the self-organized structure. The living systems are open, dynamic structures performing random, stationary, stochastic, self-organizing processes. The self-organizing procedure is defined by the spatial-temporal fractal structure, which is self-similar both in space and time. The system’s complexity appears in its energetics, which tries the most efficient use of the available energies;for that, it organizes various well-connected networks. The controller of environmental relations is the Darwinian selection on a long-time scale. The energetics optimize the healthy processes tuned to the highest efficacy and minimal loss (minimalization of the entropy production). The organism is built up by morphogenetic rules and develops various networks from the genetic level to the organism. The networks have intensive crosstalk and form a balance in the Nash equilibrium, which is the homeostatic state in healthy conditions. Homeostasis may be described as a Nash equilibrium, which ensures energy distribution in a “democratic” way regarding the functions of the parts in the complete system. Cancer radically changes the network system in the organism. Cancer is a network disease. Deviation from healthy networking appears at every level, from genetic (molecular) to cells, tissues, organs, and organisms. The strong proliferation of malignant tissue is the origin of most of the life-threatening processes. The weak side of cancer development is the change of complex information networking in the system, being vulnerable to immune attacks. Cancer cells are masters of adaptation and evade immune surveillance. This hiding process can be broken by electromagnetic nonionizing radiation, for which the malignant structure has no adaptation strategy. Our objective is to review the different sides of living complexity and use the knowledge to fight against cancer. 展开更多
关键词 Complexity Networks SMALL-WORLD Genetic Mutations SELF-ORGANIZING Self-Symmetry Energetic Balance entropy Nash Equilibrium GAMES Evolution CANCER Therapy
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ESTIMATION OF AVERAGE DIFFERENTIAL ENTROPY FOR A STATIONARY ERGODIC SPACE-TIME RANDOM FIELD ON A BOUNDED AREA
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作者 Zhanjie SONG Jiaxing ZHANG 《Acta Mathematica Scientia》 SCIE CSCD 2024年第5期1984-1996,共13页
In this paper,we mainly discuss a discrete estimation of the average differential entropy for a continuous time-stationary ergodic space-time random field.By estimating the probability value of a time-stationary rando... In this paper,we mainly discuss a discrete estimation of the average differential entropy for a continuous time-stationary ergodic space-time random field.By estimating the probability value of a time-stationary random field in a small range,we give an entropy estimation and obtain the average entropy estimation formula in a certain bounded space region.It can be proven that the estimation of the average differential entropy converges to the theoretical value with a probability of 1.In addition,we also conducted numerical experiments for different parameters to verify the convergence result obtained in the theoretical proofs. 展开更多
关键词 differential entropy STATIONARY ERGODICITY space-time random field time series
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Numerical Simulation and Entropy Production Analysis of Centrifugal Pump with Various Viscosity
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作者 Zhenjiang Zhao Lei Jiang +2 位作者 Ling Bai Bo Pan Ling Zhou 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第11期1111-1136,共26页
The fluid’s viscosity significantly affects the performance of a centrifugal pump.The entropy production method and leakage are employed to analyze the performance changes under various viscosities by numerical simul... The fluid’s viscosity significantly affects the performance of a centrifugal pump.The entropy production method and leakage are employed to analyze the performance changes under various viscosities by numerical simulation and validated by experiments.The results showed that increasing viscosity reduces both the pump head and efficiency.In addition,the optimal operating point shifts to the left.Leakage is influenced by vortex distribution in the front chamber and boundary layer thickness in wear-ring clearance,leading to an initial increase and subsequent decrease in leakage with increasing viscosity.The total entropy production Spro,Total inside the pump rises with increasing viscosity.The different mechanisms dominate under varying conditions:Turbulent dissipation dominates at low viscosity.Under high-viscosity conditions,energy loss is primarily caused by direct dissipation Spro,D and wall entropy production Spro,W.This study provides a deeper and more objective understanding of the energy characteristics of centrifugal pumps handling fluids of various viscosity,potentially aiding in optimizing pump design and improving energy conversion efficiency. 展开更多
关键词 Centrifugal pump numerical simulation VISCOSITY LEAKAGE entropy production
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Chemical Scissors Tailored Nano‑Tellurium with High‑Entropy Morphology for Efficient Foam‑Hydrogel‑Based Solar Photothermal Evaporators
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作者 Chenyang Xing Zihao Li +4 位作者 Ziao Wang Shaohui Zhang Zhongjian Xie Xi Zhu Zhengchun Peng 《Nano-Micro Letters》 SCIE EI CSCD 2024年第3期149-168,共20页
The development of tellurium(Te)-based semiconductor nanomaterials for efficient light-to-heat conversion may offer an effective means of harvesting sunlight to address global energy concerns.However,the nanosized Te(... The development of tellurium(Te)-based semiconductor nanomaterials for efficient light-to-heat conversion may offer an effective means of harvesting sunlight to address global energy concerns.However,the nanosized Te(nano-Te)materials reported to date suffer from a series of drawbacks,including limited light absorption and a lack of surface structures.Herein,we report the preparation of nano-Te by electrochemical exfoliation using an electrolyzable room-temperature ionic liquid.Anions,cations,and their corresponding electrolytic products acting as chemical scissors can precisely intercalate and functionalize bulk Te.The resulting nano-Te has high morphological entropy,rich surface functional groups,and broad light absorption.We also constructed foam hydrogels based on poly(vinyl alcohol)/nano-Te,which achieved an evaporation rate and energy efficiency of 4.11 kg m^(−2)h^(−1)and 128%,respectively,under 1 sun irradiation.Furthermore,the evaporation rate was maintained in the range 2.5-3.0 kg m^(−2)h^(−1)outdoors under 0.5-1.0 sun,providing highly efficient evaporation under low light conditions. 展开更多
关键词 TELLURIUM High entropy Electrochemical modification Solar absorption Evaporation rate
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