基于混合混沌信息加密的农业信息传输的设计与分析

文章研究了在农业信息传输过程中确保信息安全的重要性,根据混沌密码研究的现状提出一种新的复合混沌密钥设计,使其能在保留原混沌性质的基础上复杂性、有效性能进一步提高,更好的满足信息加密的需要.对加密模型模块进行设计、仿真、测试,对输出序列进行分析,从理论设计及实验分析上讨论由该模块产生的混沌序列的输出特性,使该设计能在实际中得到更好的应用     

Equilibrium regained: from nonequilibrium chaos to statistical mechanics

Far-from-equilibrium, spatially extended chaotic systems have generally eluded analytical solution, leading researchers to consider theories based on a statistical rather than a detailed knowledge of the microscopic length scales. Building on the recent discovery of a separation of length scales between macroscopic behavior and microscopic chaos, a simple far-from-equilibrium spatially extended chaotic system has been studied computationally at intermediate, coarse-grained scales. Equilibrium properties such as Gibbs distributions and detailed balance are recovered at these scales, which suggests that the macroscopic behavior of some far-from-equilibrium systems might be understood in terms of equilibrium statistical mechanics.     

Resurrection of crushed magnetization and chaotic dynamics in solution NMR spectroscopy

We show experimentally and theoretically that two readily observed effects in solution nuclear magnetic resonance (NMR)-radiation damping and the dipolar field-combine to generate bizarre spin dynamics (including chaotic evolution) even with extraordinarily simple sequences. For example, seemingly insignificant residual magnetization after a crusher gradient triggers exponential regrowth of the magnetization, followed by aperiodic turbulent spin motion. The estimated Lyapunov exponent suggests the onset of spatial-temporal chaos and the existence of chaotic attractors. This effect leads to highly irreproducible experimental decays that amplify minor nonuniformities such as temperature gradients. Imaging applications and consequences for other NMR studies are discussed.     

《微生物学》实验教学体系的创新与学生实践能力的培养

围绕高等院校《微生物学》实验教学体系的创新与学生实践能力的培养,提出亍《微生物学》实验教学的指导思想、学生实践技能的训练、教材建设、现代化教学手段的提高等创新的思路和方法,旨在进一步提高《微生物学》实验教学的质量,培养合格的专业人才。     

Anisotropy and coherent vortex structures in planetary turbulence

High-resolution numerical simulations were made of unforced, planetary-scale fluid dynamics. In particular, the simulation was based on the quasi-geostrophic equations for a Boussinesq fluid in a uniformly rotating and stably stratified environment, which is an idealization for large regions of either the atmosphere or ocean. The solutions show significant discrepancies from the long-standing theoretical prediction of isotropy. The discrepancies are associated with the self-organization of the flow into a large population of coherent vortices. Their chaotic interactions govern the subsequent evolution of the flow toward a final configuration that is nonturbulent.     

一种新的混沌激振器及其动力学特性

在分析已有混沌发生机构的基础上,结合混沌中的倍周期分叉现象,设计了一种新的混沌激振器。该激振器由2个偏心轮构成,2个偏心轮之间的约束由传统的光滑铰链改为沿圆形轨道滑动,从而使系统产生倍周期现象的条件大幅度放宽。建立了该混沌激振器的动力学模型,通过仿真试验分析其动力学特性。结果表明,较普遍应用的三连杆混沌激振器,该混沌激振器具有更强的混沌特性和更为宽松的参数选择,因而具有更大的使用范围。     

耦合混沌系统完全同步的直接方法研究

为减少耦合误差,简化耦合函数的选择过程,提出一种实现耦舍混沌系统完全同步的直接方法,该方法不需将耦合误差系统进行近似的线性化处理,也不需要知道驱动系统状态变量的取值情况。只需根据驱动系统构造相应的耦舍函数,然后利用Routh判据确定待定耦合参数。以著名Lorenz系统为例说明了该方法的有效性。     

An approach to complexity: numerical computations

The use of supercomputers and modern color-imaging techniques for numerical computation is beginning to fulfill von Neumann's vision that digital computers would become the most appropriate tool for solving nonlinear partial differential equations. An example of this approach, a model for the gas flow in the vicinity of a black hole, is described. From such calculations comes a realization that the multidimensional, dynamic solutions of nonlinear partial differential equations can exhibit complex behavior compared to what one normally encounters in analytic solutions. This complexity includes small-scale chaotic structure and large-scale persistently ordered structure. Computational methodology and the aesthetics that derive from it are discussed.     

一个多翅膀混沌系统的设计

报道了在一个双翅膀型混沌系统中生成多翅膀混沌吸引子的新结果.首先,通过构造偶对称多分段平方函数对双翅膀型混沌系统指标2的鞍焦平衡点进行扩展,从而生成多翅膀混沌吸引子.其次,分析了多翅膀混沌系统的平衡点及其性质.     

Complexity and climate

The climate that we experience results from both ordered forcing and chaotic behavior; the result is a system with characteristics of each. In forecasting prospective climate changes for the next century, the focus has been on the ordered system's responses to anthropogenic forcing. The chaotic component may be much harder to predict, but at this point it is not known how important it will be.     

论水文系统混沌特征的研究方向

简要介绍了混沌的概念，回顾了水文系统的混沌研究进展，从哲学上论证了水文系统混沌演化的普遍性，指出当前水文系统混沌研究的重点应该是探索水文系统混沌演化的普遍性，揭示水文系统混沌演化的成因机理和基本规律及其因果关系，提出了宏观、中观和微观时空尺度相结合，理论分析和计算机模拟相结合的水文系统混沌研究方法，讨论了形成混沌水文学的可能性     

Discussion: moving food regimes forward: reflections on symposium essays

All authors in this symposium use a food regime perspective to ask questions about the present which—as these articles demonstrate—have several possible answers. History suggests a time perspective of 25–40 year cycles so far—a food regime 1870–1914, an experimental and chaotic era 1914–1947, and a food regime 1947–1973. It has been less than 40 years since 1973, when food regime analysts agree that a contested and experimental period began. There is no consensus on whether it has already ended or how it might issue into a new food regime. The conversation is more fruitful than the conclusions. I intend these comments as an invitation to join in.     

高速公路交通流模型研究

文章在对已有高速公路交通流参数模型进行深入分析、研究的基础上,对参数模型中存在的一些问题进行改进;通过对几种典型的交通流状态进行仿真研究,并与实际数据比较,得出了以改进模型描述高速公路宏观交通流更具实际意义,更能准确的描述高速公路交通流的真实行为的结果。     

Chaos, strange attractors, and fractal basin boundaries in nonlinear dynamics

Recently research has shown that many simple nonlinear deterministic systems can behave in an apparently unpredictable and chaotic manner. This realization has broad implications for many fields of science. Basic developments in the field of chaotic dynamics of dissipative systems are reviewed in this article. Topics covered include strange attractors, how chaos comes about with variation of a system parameter, universality, fractal basin boundaries and their effect on predictability, and applications to physical systems.     

地形起伏多相管流段塞流流动参数计算

在起伏多相管流中常出现段塞流。段塞流流动特性参数的计算只能采用经验或半经验关系式。现场实践表明,段塞长度不仅与管径有关,而且还与气液相速度和气液相粘度等有关。结合现场试验,提出了一种计算起伏多相管流中段塞流流动特性参数的准确方法。     

基于CFD-EDM耦合的气吸式红枣捡拾机气力输送装置仿真分析

为明确气吸式红枣捡拾机气力输送装置的运动特性,开展了气力输送装置气固两相流的模拟研究.基于气固两相流理论,分别建立了计算流体模型与离散元模型,通过计算流体力学与离散单元法(computational fluid dynamics-discrete element method)耦合求解,对红枣从气力输送装置入口到出口的...     

混凝土强度预测的混沌优化神经网络模型

BP神经网络方法由于综合考虑了高强度、高性能混凝土强度的各种影响因素，能够实现非线性关系，可以用于混凝土强度预测上。为克服传统BP网络收敛速度慢、易出现麻痹现象等不足，本文采用自适应变步长(ABPM)算法来改进的BP神经网络，提出了基于混沌优化的自适应变步长(ABPM)神经网络模型，并将其预测结果和训练效率进行了分析。该方法主要利用混沌运动的遍历性为梯度算法创造一个良好的搜索界面。仿真结果表明，混沌优化的ABPM神经网络用于混凝土强度的预测，方法简单可行，搜索速度快，预测结果可靠、精度高。     

Chaos, symmetry, and self-similarity: exploiting order and disorder in mixing processes

Fluid mixing is a successful application of chaos. Theory anticipates the coexistence of order and disorder-symmetry and chaos-as well as self-similarity and multifractality arising from repeated stretching and folding. Experiments and computations, in turn, provide a point of confluence and a visual analog for chaotic behavior, multiplicative processes, and scaling behavior. All these concepts have conceptual engineering counterparts: examples arise in the context of flow classification, design of mixing devices, enhancement of transport processes, and controlled structure formation in two-phase systems.     

Chaotic Dynamics in an Insect Population

A nonlinear demographic model was used to predict the population dynamics of the flour beetle Tribolium under laboratory conditions and to establish the experimental protocol that would reveal chaotic behavior. With the adult mortality rate experimentally set high, the dynamics of animal abundance changed from equilibrium to quasiperiodic cycles to chaos as adult-stage recruitment rates were experimentally manipulated. These transitions in dynamics corresponded to those predicted by the mathematical model. Phase-space graphs of the data together with the deterministic model attractors provide convincing evidence of transitions to chaos.     

小麦条锈病受灾率时间序列混沌特征研究

利用混沌和分形理论,对湖北省襄樊地区小麦条锈病受灾率进行了混沌识别研究,对其功率谱、主分量、关联维度、最大Lyapunov指数进行了分析。结果表明,小麦条锈病受灾率时间序列具有混沌特征,属于混沌时间序列。因此建议对小麦条锈病进行建模预测时,应主要采用非线性建模方法。