A regime map for direct contact condensation

Direct-contact condensation is studied by injecting steam downward through a pipe and out of the submerged end into a pool of subcooled water. The motion of the steam/water interface is recorded by high-speed movies and systematically classified, based on the injection rate and the pool subcooling. The resulting regime map shows the existence of three main condensation modes as the injection rate is reduced: At a high rate of steam injection $\text{(>125}\text{kg/m}{}^2\text{s}\text{)}$ an oscillatory jet is observed. At a low rate of injection $\text{(<50}\text{kg/m}{}^2\text{s}\text{)}$ a phenomenon called “steam chugging,” in which the pool water periodically enters the injection pipe, is observed. At intermediate injection rates an oscillatory bubble exists continuously at the pipe exit.     

Period of the discrete Arnold cat map and general cat map

The paper first studies the period of the discrete Arnold cat map. When the modulo is composite, the formulae are developed to calculate the minimal period. When the modulo is prime, the formulae calculating the period are given and an algorithm is proposed in order to determine the minimal period. Then the paper explores the relationship between the period of the discrete general cat map and its modulo for different parameters a and b. Some period formulae are given and some properties about the period are obtained. In addition, the paper also expands the period formulae of the corresponding a-Fibonacci sequence taken the modulo for more new parameters.     

An efficient scheme for digital watermarking using chaotic map

This paper presents the new digital watermarking algorithm based on the chaotic map. Data can easily be hidden in images by using the least significant bits. In the anticipated algorithm, the logistic map is employed for locating embedding positions of chaotic watermark generation and a novel watermarking scheme is proposed. Simulation results reveal that the proposed technique is feasible and watermarks are indiscernible. The results illustrate that mean of energy, correlation, contrast, and homogeneity analyses of the proposed algorithm are quite optimal.     

Convective coupled map for simulating spatiotemporal chaos in flows

A coupled map lattices with convective nonlinearity or, for short, Convective Coupled Map (CCM) is proposed in this paper to simulate spatiotemporal chaos in fluid flows. It is found that the parameter region of spatiotemporal chaos can be determined by the maximal Liapunov exponent of its complexity time series. This simple model implies a similar physical mechanism for turbulence such that the route to spatiotemporal chaos in fluid flows can be envisaged. The study is supported by “Nonlinear Sciences Project” from the State Science and Technology Commission of China.     

Normal form for librational curves of the standard map

We present a method for constructing analytic expansions approximating librational invariant curves in the case of the so-called generalized standard map. After some preliminary changes of variables, we apply a direct Birkhoff normal form to a fixed order. The resulting system describes homotopically trivial invariant curves close to a periodic orbit. We investigate the stability of the librational curves applying a numerical method developed by J. Greene.

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Sommario Presentiamo un metodo per la costruzione di espansioni analitiche, adatte a descrivere le curve invarianti di librazione nel caso della standard map generalizzata. Dopo aver effettuato alcuni cambiamenti preliminari di variabili, calcoliamo la forma normale di Birkhoff ad un ordine fissato. Il sistema risultante descrive curve invarianti attorno ad orbite periodiche. Studiamo la stabilità di tali curve di librazione tramite un metodo numerico sviluppato da J. Greene.

     

Parameter identification and chaos synchronization for uncertain coupled map lattices

A method of chaos synchronization and parameter identification is proposed in the paper. The synchronization controller and the parameter recognizer are designed. Two coupled map lattices with different structures are taken as examples to verify the effectiveness of the method. Simulation results show that the identification variables in the parameter recognizer can substitute for the unknown parameters in both target and response systems. Then global synchronization of the two uncertain coupled map lattices can be realized after the designed controller is added.     

Stable trajectory of logistic map

In this paper, the stable trajectory of Logistic Map has been investigated by canonical duality theory from the perspective of global optimization. Numerical result of our method shows that it totally differs from traditional chaotic solution solved by Euler method. In addition, we have applied our method to three well-known standard benchmarks in global optimization. Numerical simulations are given to illustrate the effectiveness of the main results.     

Hahn-Banach Theorem of set-valued map

I.IntroductionHah-BanachTheoremisanimportantconclusioninthefunctionialanalysis.Ithaspalyedausefulroleinunsmoothanalysisandotherfields,forexample,theexistanceofthegeneralizedsubdifferentialinI2,3,6]hasbeenproved.Inthispaper,weintroducetheconceptoftheK-convexandtheK-sublinearoftheset-valuedmap,whereKisapointedandclosedandconvexconeinlocallyconvextopologicalvectorspace,andweprovethegeneralizedHahn-BanachTheoreminsection11.Weapplyittothestudyoftheexistenceofsubdifferentialfortheset-valuedmapin…     

3-periodic traveling wave solutions for a dynamical coupled map lattice

In this paper, the existence of periodic traveling wave solutions with a priori unknown velocity is considered for a coupled map lattice dynamical system. By trasforming our problem into one that involves polynomials, explicit 2- and 3-periodic traveling wave solutions are found, while the other solutions can be computed numerically. Since there does not seem to be any reports on explicit traveling wave solutions, we hope that our results will lead to the discovery of many others.     

A parallel image encryption algorithm based on the piecewise linear chaotic map and hyper-chaotic map

This paper proposes a parallel digital image encryption algorithm based on a piecewise linear chaotic map (PWLCM) and a four-dimensional hyper-chaotic map (FDHCM). Firstly, two decimals are obtained based on the plain-image and external keys, using a novel parallel quantification method. They are used as the initial value and control parameter for the PWLCM. Then, an encryption matrix and four chaotic sequences are constructed using the PWLCM and FDHCM, which control the permutation and diffusion processes. The proposed algorithm is implemented and tested in parallel based on a graphics processing unit device. Numerical analysis and experimental results show that the proposed algorithm achieves a high encryption speed and a good security performance, which provides a potential solution for real-time image encryption applications.     

Using 3-cell chaotic map for image encryption based on biological operations

Recently, image encryption has emerged as an extremely urgent need to provide high protection for secure images against being used without any authorization. In the present paper, the 3-cell chaotic map known as cycling chaos was employed for image encryption based on biological operations. In order to increase security of the proposed method, the 120-bits secret key is used. DNA Sequences and cycling chaos were used to scramble the positions of the image pixels, and then the pixels grey values were modified using a mask DNA generated by cycling chaos. The obtained results demonstrated high security of the proposed method, and it was found acceptably resistant against different well-known attacks.     

Aerodynamic map for soft and hard hypersonic level flight in near space

In this note, we design a velocity-altitude map for hypersonic level flight in near space of altitude 20-100 km. This map displays aerodynamic-related parameters associated with near space level flight, schematically or quantitatively. Various physical conditions for the near-space level flight are then characterized, including laminar or turbulent flow, rarefaction or continuous flow, aerodynamic heating, as well as conditions for sustaining level flight with and without orbital effect. This map allows one to identify conditions to have soft flight or hard flight, and this identification would be helpful for making correct planning on detailed studies of aerodynamics or making initial design of near space vehicles.     

A flow pattern map for gas—liquid flow in horizontal pipes

Various flow pattern maps for two-phase gas—liquid flow in horizontal pipes are tested against the 5935 flow pattern observations presently contained in the UC Multiphase Pipe Flow Data Bank.A new flow regime correlation representing an extension of the work done by Govier and Aziz [3] is presented and is shown to be in better agreement with the data than the other correlations tested. A computer program for this correlation is included.It is also shown that there is no significant improvement obtained by including the effects of the physical properties of the fluids using any of the physical property parameters which have been proposed so far.     

Melnikov function and Poincaré map

In this paper we give the relationship between Melnikov function and Poincare map, and a new proof for Melnikov’s method. The advantage of our paper is to give a more explicit solution and to make Melnikov function for the subharmonics bifurcation and Melnikoy function which the stable manifolds and unstable manifolds intersect transversely into a formula.     

航空电子地图及其在导航控制中的应用

航空电子地图着重表示与航空有关的地形要素与航空要素,可供研究航空区域、确定航线、判定飞机位置和飞行方向以及实施空中指挥。作为数据库,嵌入在载体的设备之中,可以作为通信、导航、制导与控制等系统的重要信号源和参考基准,共同完成系统功能及飞行任务。数字高程模型的建立及数据库的研制是航空电子地图研制的关键技术,航空电子地图在飞行模拟器仿真研究、作战指挥、武器系统地形匹配导航等方面具有广阔的应用前景。     

White-light speckle method for obtaining an equi-velocity map of a whole flow field

Experiments in Fluids - The surface of a flow seeded with aluminium oxide particles is photographed with two pulsed illuminations of whitelight. When the resultant double-exposure specklegram is...