Simulation of Power Modulation of the W7-X, TE28,8 Gyrotron

The modulation of the output power of a 140 GHz gyrotron for fusion plasma heating at the W7-X Stellarator is simulated numerically. It is shown that for appropriate beam properties, power modulation is possible. The output power shows almost no dependence on whether the accelerating voltage is being increased or decreased.     

Strongly nonlinear modal equations for nearly integrable PDEs

Summary The purpose of this paper is the derivation of reduced, finite-dimensional dynamical systems that govern the near-integrable modulations ofN-phase, spatially periodic, integrable wavetrains. The small parameter in this perturbation theory is the size of the nonintegrable perturbation in the equation, rather than the amplitude of the solution, which is arbitrary. Therefore, these reduced equations locally approximate strongly nonlinear behavior of the nearly integrable PDE. The derivation we present relies heavily on the integrability of the underlying PDE and applies, in general, to anyN-phase periodic wavetrain. For specific applications, however, a numerical pretest is applied to fix the truncation orderN. We present one example of the reduction philosophy with the damped, driven sine-Gordon system and summarize our present progress toward application of the modulation equations to this numerical study.     

Proving total dual integrality with cross-free families—A general framework

We present a theorem stating that certain classes of linear programming problems have integer optimal (primal and dual) solutions. The theorem includes as special cases earlier results of Johnson, Edmonds and Giles, Frank, Hoffman and Schwartz, Gröflin and Hoffman, and Lawler and Martel. The proof method consists of deriving total dual integrality for the corresponding system of linear inequalities from the total unimodularity of certain ‘cross-free’ subsystems. The scheme presented here differs from the one proposed earlier by Grishuhin in that Grishuhin requires the total unimodularity of cross-free subsystems in the axioms, whereas here this follows from easier verifiable axioms.     

单模光纤脉冲展宽效应实验研究

利用时间分辨率为2ps的扫描相机和实时处理系统研究了当脉宽为15ps波长为1.06μm的Nd:YAG激光脉冲在单模光纤中传输时,光纤中自相位调制(SPM),正群速色散(GVD)和受激喇曼散射(SRS)引起的联合非线性效应。     

Respiratory modulation of heart beat-to-beat interval in diabetic patients

We have analyzed simultaneous recordings of respiration and heartbeat intervals in diabetic patients and control subjects. Our main findings are that in diabetic patients the heart beat-to-beat interval variability and cardiorespiratory crosscorrelation are decreased, the autocorrelation time of the interval series is increased, and the phase relation of the respiration with the heartbeat interval oscillations is often reversed in comparison with the control subjects. We have been able to reproduce the data using a biophysical model in which the time dependent input signal to the sinoatrial node was constituted of quasiperiodic and aperiodic components. The quasiperiodic input was obtained from the recording of the respiratory signal and the aperiodic input was obtained from selected realizations of correlated noise. Our study indicates that both input components to the sinoatrial node are modified in diabetic patients.     

Millimeter-wave Low Sidelobe Time Modulated Linear Arrays with Uniform Amplitude Excitations

The study of millimeter-wave low sidelobe linear arrays with time modulation technique is presented in this paper. Special emphasis is on the realization of low sidelobes with uniform amplitude excitations, which are easier for the practical implementation. Two types of time modulated linear arrays with uniform amplitude excitations, namely, the variable aperture size (VAS) linear arrays with optimized time sequences and the linear arrays with optimized random time sequences were studied. The optimized time sequences are obtained via the differential evolution (DE) algorithm and the genetic algorithm (GA). Many factors that affect the array performance are discussed. Supported by the National Natural Science Foundation of China (No. 60571023), the SRF for ROCS, SEM, and the innovative Research Team Program of UESTC, China.     

Real-time parameter estimation for degrading and pinching hysteretic models

Many civil and mechanical structures exhibit hysteresis with degradation and/or pinching when subject to severe cyclic loadings such as earthquakes, wind, or sea waves. The modeling and identification of non-linear hysteretic systems with degradation and pinching is therefore a practical problem encountered in the engineering mechanics field. On-line identification of degrading and pinching hysteretic systems is quite a challenging problem because of its complexity. A recently developed technique, the unscented Kalman filter (UKF) which is capable of handling any functional non-linearity, is applied to the on-line parametric system identification of hysteretic differential models with degradation and pinching. Simulation results show that the UKF is efficient and effective for the real-time state estimation and parameter identification of highly non-linear hysteretic systems with degradation and pinching.     

Ⅱ类攻能性反应Holling—Tanner干扰系统的正周期解的存在性

利用重合度连续定理，研究Ⅱ类攻能性反应Holling—Tanner干扰系统正周期解的存在性，得到了该系统正周期解存在的充分条件。     

A fully vectorial effective index method to analyse the propagation properties of microstructured fiber

Based on numerical simulation, we theoretically study the linear and nonlinear properties of microstructured fiber. Using the fully vectorial effective index method, we calculate the effective refractive index for different air hole size. We show how the linear properties such as spot size, numerical aperture, splice loss and bend loss can be controled by changing the air hole size. We also propose the same method for analysing effective area and self-phase modulation of microstructured fiber for different designing parameters. We compare all our results with other numerical methods.     

A model to characterize the effect of cross phase modulation on polarization in an optical fiber transmission system

This paper presents a model that described the process of inter-influence between cross phase modulation (XPM) and polarization effects such as polarization mode dispersion (PMD) and polarization dependant loss (PDL) in an optical fiber communication system. Previous papers have discussed PMD-PDL and PMD-XPM effects in separate models, but in this work we developed a model that is capable of characterizing and evaluating PMD, PDL and XPM simultaneously. From the model, we found that PMD and PDL can be affected by XPM. The presence of XPM changed the vector directions of PMD and PDL in Stokes space.