High Repetition Rate Fiber Laser Coupled to a Linear Cavity Generating Picosecond Pulses

An experimental investigation is presented for obtaining picosecond (ps) pulses at a repetition rate of 11 GHz using a fiber laser coupled to an external cavity. Without applying active mode locking and without a nonlinear element in the coupled cavity, pulses of about 15 ps with an average power of 20 mW have been generated using a (cw) diode pump laser. The pulse duration decreases with increasing repetition rate.     

Transition to chaos in the conservative four-wave parametric interactions

In this work, we analyze the transition from regular to chaotic states in the parametric four-wave interactions. The temporal evolution describing the coupling of two sets of three-waves with quadratic nonlinearity is considered. This system is shown to undergo a chaotic transition via the separatrix chaos scenario, where a soliton-like solution (separatrix) that is found for the integrable (perfect matched) case becomes irregular as a small mismatch is turned on. As the mismatch is increased the separatrix chaotic layer spreads along the phase space, eventually engrossing most part of it. This scenario is typical of low-dimensional Hamiltonian systems.     

双近贴管纳秒单幅高速摄影机

作为一种性能优越的二维图象记录设备,双近贴管纳秒单幅高速摄影机在高速摄影领域已越来越受到人们的重视。这方面的研究成果已经而且正在为核物理研究及其它学学科的发展提供有效的测量工具。     

Analysis of complex industrial samples by gas chromatography; a report on selected past activities

Summary A review of past activities concerning selected industrial analytical problems is given. This includes the following question: preparation of pure gas mixtures to be used for calibration, catalytic conversion of ester and pyridin samples to carbon dioxide and a one-point calibration method using peak heights, both for quantitative analysis, analysis of gas mixtures containing fluorine and inorganic fluorine compounds and the determination of the oxygen and fluorine content of the sample, separation and identification of hydrocarbons in shale oil and petroleum fraction samples, and analysis of wine.     

On the problem of directed signal transmission and energy transfer in molecular systems

A new physical interpretation of the mechanism of directed energy transfer and signal transmission in molecular systems along one-dimensional chains capable of successive isomerization is proposed. The photoacceptor—transmitting chain—reaction center system is considered as a model. Conditions under which the directed energy transfer occurs from the photoacceptor to the reaction center along the chain are analyzed. The time of signal transmission depends on the chain length, and the transmission coefficient is mainly determined by the characteristics of the initial and final elements in the whole system.     

Removal of Disperse Dyes from Water Using Surfactant Treated Alumina

An alumina surface was modified by adsorption of an anionic surfactant, sodium dodecyl sulfate (SDS). Typical S‐shaped isotherm of surfactant on alumina was observed. The adsorption of Disperse Red‐11, Disperse Blue‐26 and Disperse Red‐156 on alumina and surfactant treated alumina has been investigated. The enhancement in adsorption of these disperse dyes on surfactant treated alumina is observed, which may be attributed to their solubilization in surfactant aggregates formed at the solid/liquid interface. The effect of pH on adsorption has been studied. The adsorption is greatly influenced by pH of the medium. The applicability of the Langmuir model and the Dual‐Mode sorption model (DSM) were tested for equilibrium data.     

Design of the H10□ to H01° Sector-Type Mode Converter at Ka-Band

A design procedure for the H₁₀^□ to H₀₁^° sector-type mode converter at Ka-band is described in detail. As an example, an H₁₀^□ to H₀₁^° sector-type mode converter with an input rectangular port size as 7.112×3.556 mm² and another output circular port diameter as 17.2 mm is designed and measured for insertion losses and wanted mode pattern. The mode converting efficiency from H₁₀^□ mode to H₀₁^° mode is about 91.2%. The insertion losses of the converter are lower than 0.1525 dB with 2GHz band.     

无限时域预测控制的直接求解算法

在预测控制中，当预测时域取为无穷大时通常可保证闭环系统的稳定性，本文通过分析和利用这种算法的本质，把上述问题转化为一个具有部分状态等式约束的二次优化过程，获得了一种直接的算法，避免了传统方法需要迭代的缺点。     

Rheological transitions in asymmetric colloidal star mixtures

We examine the rheological transition from an arrested to a fluid state for different mixtures of star polymers with varying functionality and size ratios. As a general trend, we find that addition of smaller star polymers in an arrested, concentrated solution of larger ones brings about melting of the large star glass. At the same time, the dependence of the amount of additives needed to melt the glass has a nontrivial dependence on the size ratio. Theoretical analysis, based on effective interactions and Mode Coupling Theory, reproduces the experimental results and helps identify two distinct types of glasses in the composite system. This paper was presented at Annual European Rheology Conference (AERC) held in Hersonisos, Crete, Greece, April 27–29, 2006.     

Modeling and control of surface gravity waves in a model of a copper converter

Undesirable splashing appears in copper converters when air is injected into the molten matte to trigger the conversion process. We consider here a cylindrical container horizontally placed and containing water, where gravity waves on the liquid surface are generated due to water injection through a lateral submerged nozzle. The fluid dynamics in a transversal section of the converter is modeled by a 2-D inviscid potential flow involving a gravity wave equation with local damping on the liquid surface. Once the model is established, using a finite element method, the corresponding natural frequencies and normal modes are numerically computed in the absence of injection, and the solution of the system with injection is obtained using the spectrum. If a finite number of modes is considered, this approximation leads to a system of ordinary differential equations where the input is represented by the fluid injection. The dynamics is simulated as perturbations around a constant fluid injection solution, which is the desired operating state of the system, considering that the conversion process does not have to be stopped or seriously affected by the control. The solution is naturally unstable without control and the resulting increase of amplitude of the surface waves are assimilable to the splashing inside the converter. We show numerically that a variable flow around the operating injection is able to sensibly reduce these waves. This control is obtained by a LQG feedback law by measuring the elevation of the free surface at the point corresponding to the opposite extreme to where the nozzle injection is placed.