Frequency-Shift of a Frequency Stabilized Laser Based on Zeeman Effect

We introduce a new method of frequency-shifting for a diode laser in laser cooling experiments, the method is based on the Zeeman egect of^87 Rb atoms. The laser frequency is stabilized by absorption spectrum line of atoms in magnetic field. We show that a magnetic field can be added up to 10^-2T. The corresponding frequency shift is 10^2 MHz and the response time is about 1ms. The large range of the frequency shift is suffcient for laser-cooling experiments.     

Voxel classification methodology for rapid Monte Carlo simulation of light propagation in complex media

Monte Carlo (MC) method is a statistical method for simulating photon propagation in media in the optical molecular imaging field.However,obtaining an accurate result using the method is quite time-consuming,especially because the boundary of the media is complex.A voxel classification method is proposed to reduce the computation cost.All the voxels generated by dividing the media are classified into three types (outside,boundary,and inside) according to the position of the voxel.The classified information is used to determine the relative position of the photon and the intersection between photon path and media boundary in the MC method.The influencing factors and effectiveness of the proposed method are analyzed and validated by simulation experiments.     

A Pseudo Arc-Length Method for Numerical Simulation of Shock Waves

A pseudo arc-length method is proposed for the numerical simulation of shock wave propagations. This method passes the discontinuities and establishes adaptive moving meshes in the physical space by introducing the arc-length parameter and transforming the computational domain. Numerical experiments of the Sod problem, double Mach reflection problem and explosion problem demonstrate that this approach is more efficient than traditional numerical methods in capturing and tracking discontinuous solutions of singular or nearly singular problems.     

A PATTERN RECOGNITION APPROACH FOR TONE CLASSIFICATION OF ISOLATED SYLLABLE IN PUTONGHUA

In this paper,a new approach of pattern recognition for tone classification of Putonghua Which is im-portant for speech recognition of Putonghua is discribed.In this method,four parameters of the fundamen-tal frequency trajectory are selected based on a large number of statistical experiments.It is assumed thatthe four parameters satisfy multidimensional Gaussion distribution and a non-Euclidean distancefunction for each tone class is derived according to the rule of minimum probability of calssification error.the optimal decision results are obtained in a sense of statistics.It is proved that this method provides verysatisfactory results by the experiments for speaker-independent tone classification of Putonghua.     

Design and experiments for the waveguide to coaxial cable adapter of a cavity beam position monitor

The waveguide to coaxial cable adapter is very important to the cavity beam position monitor (CBPM) because it determines how much of the energy in the cavity could be coupled outside. In this paper, the waveguide to coaxial cable adapter of a CBPM is designed and experiments are conducted. The curve shapes of experiments and simulations are very similar and the difference in reflection is less than 0.1. This progress provides a reliable method for designing the adapter.     

Perfect synchronization of chaotic systems： a controllability perspective

This paper presents a synchronization method, motivated from the constructive controllability analysis, for two identical chaotic systems. This technique is applied to achieve perfect synchronization for Lorenz systems and coupled dynamo systems. It turns out that states of the drive system and the response system are synchronized within finite time, and the reaching time is independent of initial conditions, which can be specified in advance. In addition to the simultaneous synchronization, the response system is synchronized un-simultaneously to the drive system with different reaching time for each state. The performance of the resulting system is analytically quantified in the face of initial condition error, and with numerical experiments the proposed method is demonstrated to perform well.     

An improved loopless mounting method for cryocrystallography

Based on a recent loopless mounting method, a simplified loopless and bufferless crystal mounting method is developed for macromolecular crystallography. This simplified crystal mounting system is composed of the following components: a home-made glass capillary, a brass seat for holding the glass capillary, a flow regulator, and a vacuum pump for evacuation. Compared with the currently prevalent loop mounting method, this simplified method has almost the same mounting procedure and thus is compatible with the current automated crystal mounting system. The advantages of this method include higher signal-to-noise ratio, more accurate measurement, more rapid flash cooling, less x-ray absorption and thus less radiation damage to the crystal. This method can be extended to the flash-freeing of a crystal without or with soaking it in a lower concentration of cryoprotectant, thus it may be the best option for data collection in the absence of suitable cryoprotectant. Therefore, it is suggested that this mounting method should be further improved and extensively applied to cryocrystallographic experiments.     

A method for phase reconstruction in optical three-dimensional shape measurement

In optical three-dimensional shape measurement, a method of improving the measurement precision for phase reconstruction without phase unwrapping is analyzed in detail. Intensities of any five consecutive pixels that lie in the x-axis direction of the phase domain are given. Partial derivatives of the phase function in the x-and y-axis directions are obtained with a phaseshifting mechanism, the origin of which is analysed. Furthermore, to avoid phase unwrapping in the phase reconstruction, we derive the gradient of the phase function and perform a two-dimensional integral along the x- and y-axis directions. The reconstructed phase can be obtained directly by performing numerical integration, and thus it is of great convenience for phase reconstruction. Finally, the results of numerical simulations and practical experiments verify the correctness of the proposed method.     

Bulk sound velocity of porous materials at high pressures

A correction of Walsh's method for bulk sound velocity calculation for shocked porous materials is accomplished based on the Wu－Jing thermodynamic equation of state. The corrected bulk velocities for solid and porous samples with low porosities are in good agreement with the corresponding experimental data published previously. On the basis of this corrected equation, the influence of thermoelectrons on the bulk velocity of shocked materials is discussed in detail at pressures of 50, 70 and 200 GPa. Some interesting phenomena are revealed, which seem to be the unique features of a dynamic-pressure-loading process and could not be found in static experiments.     

A METHOD FOR NUMERICAL PREDICTION OF THE AVERAGE SOUND FIELD IN SHALLOW WATER

The theory of the smooth-average field in shallow water is presented;the smooth-average expres-sion suitable for long ranges and the image-source expression suitable for short ranges are combinedtogether to give a more complete calculating method of the average field.The correspondingcomputer programs,which make the calculation of the average field easy and rapid,have heendeveloped.Some examples of application of the method are given,and the calculated results arequite consistent with the experiments.