一种测试"复杂性"的新方法

对于一个生物系统 ,我们应该如何去测定它的复杂性呢 ?最近美国哈佛大学医学院和葡萄牙里斯本大学的Ｍ .Ｃｏｓｔａ教授及其研究小组提出了一个新的设想 ,他们认为疾病与衰老可以用信息的损失来定量描述 .换句话说 ,一个生物组织 (或器官 )的复杂性是与它对环境的适应性和它的功能性的发挥有着密切的关系 ,而疾病与衰老将会降低生物组织 (器官 )的复杂性 ,使得它们不容易适应环境的变化以及抵抗灾变事件的能力 .但是传统对复杂性的描述常常是与这种“信息损失理论”相矛盾的 ,按信息科学的观点来说 ,一个系统的复杂性是由该系统能生成多少新…     

复杂性科学的几大学派及其研究特点

 近几十年来,国际学术界出现了一门新学科---复杂性科学,它致力于复杂系统理论与现有传统学科交叉的研究,目前已掀起了一股研究复杂性和非线性问题的热潮,数学家、物理学家、经济学家、生物学家和计算学家等都在共同开展这一问题的研究,复杂性科学将成为一个驾驭在21世纪生命科学、信息科学、材料科学等高新领域之间的一个横断学科,被誉于“21世纪的科学”。本文从哲学角度分析了现代科学中还原论和简单性思维方式的起源以及复杂性科学诞生的背景,研究了目前复杂性科学研究的几大学派的基本特征,指出应汲取各大学派的优点,结合我国的实际情况,全面推进我国的复杂性科学研究。     

格子复杂性和符号序列的细粒化

提出一种新的有限长一维符号序列的复杂性度量——格子复杂性，建立在Lempel Ziv复杂性和一维迭代映射系统的符号动力学基础上.同时提出了符号序列的细粒化方法，可与格子复杂性以及Lempel Ziv复杂性结合.新度量在细粒化指数较小时与Lempel Ziv复杂性基本一致，在细粒化指数增大时显示出截然不同的特性.以Logistic映射为对象的计算实验表明，格子复杂性对混沌区的边缘最敏感.最后还讨论了上述复杂性度量的其他一些重要性质. 关键词： 混沌 复杂性度量 格子复杂性 细粒化     

物理学研究的新领域——探索复杂性

文章介绍了近代科学思想和方法论中的两个基本模式,即还原论和系统论,指出在物理学及其交叉学科中探索复杂系统将是未来科学发展的一个重要领域,它们共同构成复杂性科学.文章说明了复杂网络的一些特殊性质,它们可以用来描述一些复杂系统的结构和功能.作为一个导引,文章还介绍了国内外研究复杂系统的主要学术流派,并重申复杂性研究以及交叉学科对中国中长期科学发展的重要意义.     

人类认识从追求“简单性”走向探索“复杂性”(下)——科学发展的人文历程漫话之十六

论述了追求"简单性"与探索"复杂性"的关系,介绍了当前"复杂性"研究的主要领域——非线性科学,论证了非线性是系统"复杂性"的根源.     

气液两相流电导波动信号复杂性测度分析及其流型表征

为了考察从时间序列提取的复杂性测度与气液两相流流型变化之间的关系，本文首先讨论了三种复杂性测度(Lempel-Ziv复杂性、功率谱熵和近似熵)对周期信号、随机信号、混合随机信号和混沌信号的识别能力，然后分析了时间序列长度对复杂性计算的影响.在此基础上，从实际测量的80种垂直上升管中气液两相流电导波动信号中提取了这三种复杂性测度，结果表明：三种复杂度对两相流流型变化是敏感的，通过对三种复杂度随两相流流动参数变化规律分析，可以得到气液两相流动力学结构反演特征，为揭示气液两相流流型转化机理提供了一种有效的辅助诊断工具. 关键词： 气液两相流 Lempel和Ziv复杂性 功率谱熵 近似熵     

基于多尺度熵的交通流复杂性分析

交通流演化复杂性的研究有助于深刻理解交通系统的内在演化规律,为交通流的预测和控制提供理论依据.多尺度熵方法在生理时间序列和计算机网络流量的分析中得到了广泛的应用.考虑到交通流中的车辆到达和计算机网络中的分组到达具有类似特性,本文以刹车灯模型的车头时距为分析对象,利用多尺度熵方法来分析交通流演化的复杂性.分析结果表明:1)车头时距的复杂性随着时间尺度的增加而降低,反映了交通流的短时间难预测性;2)当时间尺度较小时,车头时距复杂性在自由流时和同步流时差异不大,但是,随着时间尺度的增加,自由流时车头时距的熵值迅速下降,而同步流时车头时距的熵值下降较慢.这一特性对于识别自由流中是否产生了同步流有非常重要的参考价值.本文的研究可以为揭示交通流演化的复杂性提供新的思路和方法.     

基于OPM的电子信息装备体系复杂性建模

对于电子信息装备体系的复杂系统,以往以还原论为指导的建模方法无法充分体现电子信息装备体系的涌现性等复杂性,探索采用应对复杂性的对象过程方法论(OPM)来解决此难题。根据传统系统级或体系级建模在方法论上的根本困难,分析电子信息装备体系复杂性建模需求。基于对象过程方法论研究电子信息装备体系建模方法,在统一视图框架下同时对电子信息装备体系组成中不同领域、不同专业的结构、功能和行为建模,通过OPM分别对电子信息装备体系结构和对抗过程进行建模,再把这两个静动态模型结合起来进行整体概念建模。以防空反导体系对抗为例,演示了OPM进行体系概念模型开发的方法,说明了方法的有效性。     

第八讲 人脑电图的复杂性

利用非线性动力学复杂性的测度研究了人脑电图在不同的功能状态下的信息传递，并定义了不同层次的复杂性的测度，认为这种方法可作为研究人脑高级功能的一种方法。     

生命科学中的物理问题讲座第八讲人脑电图的复杂性

利用非线性动力学复杂性的测度研究了人脑电图在不同的功能状态下的信息传递，并定义了不同层次的复杂性的测度，认为这种方法可作为研究人脑高级功能的一种方法。     

Complexity in everything

Cosmic Catastrophes. By R. Chapman and David Morrison. 1989, £22·95, pp. viii + 302. Plenum, ISBN 0306 431637. Scope: Textbook. Level: Postgraduate.

The origin of the solar system: The Capture Theory. By J. R. Dormand and M. M. Woolfson. 1989, £29·95, pp. 230. Ellis Horwood, ISBN 0 7458 0601 5. Scope: Textbook. Level: Postgraduate.

Getting the Measure of the Stars. By W. A. Cooper and E. N. Walker. 1989, £14·95, pp. xii + 293. Adam Hilger, ISBN 0 85274 830 2. Scope: Textbook. Level: General reader.

Observing Variable Stars. A guide for the beginner. By David H. Levy. 1989, £13·95, pp. xix+198. Cambridge University Press, ISBN 0 521 32133 1. Scope: Text.

Space Plasma Physics. 1. Stationary Processes By A. Hasegawa and T. Sato. 1989, DM110·00, pp. xi+173, Springer, ISBN 3 540 5041177. Scope: Monograph. Level: Postgraduate.

Multiwavelength Astrophysics. Edited by F. Cordova. 1988, £30·00, pp. xii + 400. Cambridge University Press, ISBN 0 521 36197 4. Scope: Conference proceedings. Level: Postgraduate.

Squeezed and Nonclassical Light. Edited by R. Tombesi and E. R. Pike. 1989, £75·00, pp. x + 335. Plenum, ISBN 0 306 43084 3. Scope: Conference proceedings. Level: Postgraduate.

Photons and Nonlinear Optics. By Professor D. N. Klyshko, Translated by Yuri Sviridov. 1988, $298·00, pp. xix + 415. Gordan and Breach, ISBN 2 88124 6699. Scope: Textbook. Level: Postgraduate.

Laser Interaction and Related Plasma Phenomena. Volume 8. Edited by Heinrich Hora and George H. Miley. 1988, $115·00, pp. xix + 743. Plenum, ISBN 0 306 43007 X. Scope: Conference proceedings. Level: Postgraduate

Spectrally Selective Surfaces for Heating and Cooling Applications. By C. G. Grandqvist. 1989, $38.00 (N. America), $44.00 (all other countries), pp. viii + 120. SPIE Optical Engineering Press, ISBN 0 8194 0228 1. Scope: Text. Level: Postgraduate.

Superheavy Elements. By Krishna Kumar. 1989, £25·00, pp. xvi+150. Adam Hilger, ISBN 0 85274 097 2. Scope: Text. Level: Postgraduate.

Nuclear Fusion. By Keighiro Niu. 1989, £35·00, pp. xii + 240. Cambridge University Press, ISBN 0 521 329949. Scope: Textbook. Level: Postgraduate.

Advances in Nuclear Physics. Volume 19. Edited by J. W. Negele and Erich Vogt. 1989, $72·00, pp. xvi + 380. Plenum, ISBN 0 306 43046 0. Scope: Review. Level: Specialist.

The Elements: Their origin, abundance and distribution. By P. A. Cox. 1989, £25·00 (hbk), £9·95 (pbk), pp. viii + 207. Oxford University Press, ISBN 0 19 855275 0 (hbk); 0 19 855298 (pbk). Scope: Textbook. Level: Undergraduate.

The Elements. By John Emsley. 1989, £9·95 (pbk), pp. vii + 256. Clarendon Press, ISBN 0 19 855237 8. Scope: Reference. Level: General reader.

Electrical Properties of Biopolymers and Membranes. By S. Takashima. 1989, £55·00, pp. xi + 396. Adam Hilger, ISBN 0 85274 1367. Scope: Textbook. Level: Postgraduate.

Thermal Conduction in Semiconductors. By C. M. Bhandari and D. M. Rowe. 1988, £15·95, pp. xvi + 224. John Wiley &; Sons, ISBN 0 470 21049 4. Scope: Textbook. Level: Advanced undergraduate/postgraduate.

Introduction to the Theory of Disordered Systems. By Ilya M. Lifshits, Sergei A. Gredeskul and Leonid A. Pastur. 1988, £55·00, pp. xviii + 462. John Wiley &; Sons, ISBN 0 471 87533 3. Scope: Text. Level: Postgraduate.

Defects and Structural Phase Transitions. By A. P. Levanyuk and A. S. Sigov. 1988, $112·00, pp. xiv + 208. Gordon and Breach, ISBN 2 88124 0674. Scope: Monograph. Level: Postgraduate.

Solid-State Physics Source Book. Edited by S. P. Parker. 1988, £45·00, pp. 381. McGraw-Hill Book Company, ISBN 0 07 045503 1. Scope: Reference text. Level: Undergraduate.

The Kinematics of Mixing: Stretching, Chaos and Transport. By J. M. Ottino. 1989, £50·00 (hbk), £20·00 (pbk), pp. xiv + 364. Cambridge University Press, ISBN 0 521 363357 (hbk): 0 521 36878 2 (pbk). Level: Specialist.

Computer Simulation of Liquids. By M. P. Allen and D. J. Tildesley. 1989, £20·00, pp. xix + 385. Oxford University Press, ISBN 019 855645 4. Scope: Research. Level: Postgraduate.

Quantum Electrodynamics at High Energies. By P. S. Isaev. 1989, £26·75 (hbk), pp. viii + 263. Adam Hilger, IOP Publishing Ltd, ISBN 0 88318 572 5. Scope: Textbook Level: Postgraduate.

Low Dimensional Sigma Models. By W. J. Zakrzewski. 1989, £25·00, pp. xiii + 289. Adam Hilger, ISBN 085274231 2. Scope: Text. Level: Specialist.

Nonlinear Physics. From the Pendulum to Turbulence and Chaos. By R. Z. Sagdeev, D. A. Usikov and G. M. Zaslavsky. 1988, $98·00 (hbk), $39·00 (pbk), pp. xxiii + 675. Harwood Academic Publishers, ISBN 3 7186 4828 8 (hbk), 3 7186 4829 6 (pbk). Scope: Textbook. Level: Postgraduate.

Introduction to Computing with Pascal. By Norman L. Biggs. 1989, £20·00, pp. x + 219. Clarendon, ISBN 0 19 853755 7. Scope: Text. Level: Undergraduate.

Parallel Computing: Methods, Algorithms and Applications. Edited by D. J. Evans and C. Sutti. 1989, £30·00, pp. x + 287. Adam Hilger, ISBN 0 85274 224 X. Scope: Conference proceedings. Level: Postgraduate.

Lithography in Microelectronics. Edited by T. M. Makhviladze. 1989, $62·00 (U.S.A. &; Canada), $75·00 (other countries) pp. x + 207. Nova Science, ISBN 0 941743 30 6. Scope: Multiauthor reviews. Level: Research student.     

Quantum Communication Complexity

Can quantum communication be more efficient than its classical counterpart? Holevo's theorem rules out the possibility of communicating more than n bits of classical information by the transmission of n quantum bits—unless the two parties are entangled, in which case twice as many classical bits can be communicated but no more. In apparent contradiction, there are distributed computational tasks for which quantum communication cannot be simulated efficiently by classical means. In some cases, the effect of transmitting quantum bits cannot be achieved classically short of transmitting an exponentially larger number of bits. In a similar vein, can entanglement be used to save on classical communication? It is well known that entanglement on its own is useless for the transmission of information. Yet, there are distributed tasks that cannot be accomplished at all in a classical world when communication is not allowed, but that become possible if the non-communicating parties share prior entanglement. This leads to the question of how expensive it is, in terms of classical communication, to provide an exact simulation of the spooky power of entanglement.     

Complexity of two-dimensional patterns

To describe quantitatively the complexity of two-dimensional patterns we introduce a complexity measure based on a mean information gain. Two types of patterns are studied: geometric ornaments and patterns arising in random sequential adsorption of discs on a plane (RSA). For the geometric ornaments analytical expressions for entropy and complexity measures are presented, while for the RSA patterns these are calculated numerically. We compare the information-gain complexity measure with some alternative measures and show advantages of the former one, as applied to two-dimensional structures. Namely, this does not require knowledge of the “maximal” entropy of the pattern, and at the same time sensitively accounts for the inherent correlations in the system. Received 12 November 1999     

Network Geometry and Complexity

Higher order networks are able to characterize data as different as functional brain networks, protein interaction networks and social networks beyond the framework of pairwise interactions. Most notably higher order networks include simplicial complexes formed not only by nodes and links but also by triangles, tetrahedra, etc. More in general, higher-order networks can be cell-complexes formed by gluing convex polytopes along their faces. Interestingly, higher order networks have a natural geometric interpretation and therefore constitute a natural way to explore the discrete network geometry of complex networks. Here we investigate the rich interplay between emergent network geometry of higher order networks and their complexity in the framework of a non-equilibrium model called Network Geometry with Flavor. This model, originally proposed for capturing the evolution of simplicial complexes, is here extended to cell-complexes formed by subsequently gluing different copies of an arbitrary regular polytope. We reveal the interplay between complexity and geometry of the higher order networks generated by the model by studying the emergent community structure and the degree distribution as a function of the regular polytope forming its building blocks. Additionally, we discuss the underlying hyperbolic nature of the emergent geometry and we relate the spectral dimension of the higher-order network to the dimension and nature of its building blocks.     

Complexity of hierarchical ensembles

Within the framework of generalized combinatorial approaches, complexity is determined as a disorder measure for hierarchical statistical ensembles related to Cayley trees possessing arbitrary branching and number of levels. With strengthening hierarchical coupling, the complexity is shown to increase monotonically to the limit value that grows with tree branching. In contrast to the temperature dependence of thermodynamic entropy, the complexity is reduced by the variance of hierarchical statistical ensemble if the branching exponent does not exceed the gold mean. Time dependencies are found for both the probability distribution over ensemble states and the related complexity. The latter is found explicitly for self-similar ensemble and generalized for arbitrary hierarchical trees.