Complex coordinate rotation method based on gradient optimization

In atomic,molecular,and nuclear physics,the method of complex coordinate rotation is a widely used theoretical tool for studying resonant states.Here,we propose a novel implementation of this method based on the gradient optimization(CCR-GO).The main strength of the CCR-GO method is that it does not require manual adjustment of optimization parameters in the wave function;instead,a mathematically well-defined optimization path can be followed.Our method is proven to be very efficient in searching resonant positions and widths over a variety of few-body atomic systems,and can significantly improve the accuracy of the results.As a special case,the CCR-GO method is equally capable of dealing with bound-state problems with high accuracy,which is traditionally achieved through the usual extreme conditions of energy itself.

New method for oblique impact dynamics research of a flexible beam with large overall motion considering impact friction force

A flexible beam with large overall rotating motion impacting with a rigid slope is studied in this paper. The tangential friction force caused by the oblique impact is analyzed. The tangential motion of the system is divided into a stick state and a slip state. The contact constraint model and Coulomb friction model are used respectively to deal with the two states. Based on this hybrid modeling method, dynamic equations of the system, which include all states（before, during, and after the collision）are obtained. Simulation results of a concrete example are compared with the results obtained from two other models： a nontangential friction model and a modified Coulomb model. Differences in the results from the three models are discussed. The tangential friction force cannot be ignored when an oblique impact occurs. In addition, the results obtained from the model proposed in this paper are more consistent with real movement.

FPGA Implementation of Wave Pipelining CORDIC Algorithms

The implementation of the coordinate rotational digital computer （CORDIC） algorithm with wave pipelining technique on field programmable gate array （FPGA） is described. All data in FPGA-based wave pipelining pass through a number of logic gates, in the same way that all data pass through the same number of registers in a conventional pipeline. Moreover, all paths are routed using identical routing resources. The manual placement, timing driven routing and timing analyzing techniques are applied to optimize the layout for achieving good path balance. Experimental results show that a 256-LUT logic depth circuit mapped on XC4VLX15-12 runs as high as 330 MHz, whichis a little lower than the speed of 336 MHz based on the conventional 16-stage pipelining in the same chip. The latency of the wave pipelining circuit is 30.3 ns, which is 36.4% shorter than the latency of 16-stage conventional pipelining circuit.

Numerical Investigation of Submarine Hydrodynamics and Flow Field in Steady Turn

This paper presents numerical simulations of viscous flow past a submarine model in steady turn by solving the Reynolds-Averaged Navier-Stokes Equations（RANSE） for incompressible, steady flows. The rotating coordinate system was adopted to deal with the rotation problem. The Coriolis force and centrifugal force due to the computation in a bodyfixed rotating frame of reference were treated explicitly and added to momentum equations as source terms. Furthermore, velocities of entrances were coded to give the correct magnitude and direction needed. Two turbulence closure models（TCMs）, the RNG k-ε model with wall functions and curvature correction and the Shear Stress Transport（SST） k-ω model without the use of wall functions, but with curvature correction and low-Re correction were introduced, respectively. Take DARPA SUBOFF model as the test case, a series of drift angle varying between 0° and 16° at a Reynolds number of 6.53×10^6 undergoing rotating arm test simulations were conducted. The computed forces and moment as a function of drift angle during the steady turn are mostly in close agreement with available experimental data. Though the difference between the pressure coefficients around the hull form was observed, they always show the same trend. It was demonstrated that using sufficiently fine grids and advanced turbulence models will lead to accurate prediction of the flow field as well as the forces and moments on the hull.

Research on Open-circuit Fault Tolerant Control of Six-phase Permanent Magnet Synchronous Machine Based on Fifth Harmonic Current Injection

This paper proposes a novel control approach for fault-tolerant control of dual three-phase permanent magnet synchronous motor(PMSM) under one-phase open-circuit fault.A modified six-phase static coordinate transformation matrix and an extended rotating coordinate transformation matrix are investigated considering the influence of the fifth harmonic space on fault-tolerant control. These mathematical models are further analyzed in the fundamental space and the fifth harmonic space after the fault and to eliminate the coupling between the d-q axis voltage equation in the fundamental wave space and the d-q axis voltage equation in the fifth harmonic space, a secondary rotation coordinate transformation matrix is proposed. To achieve the purpose of reducing torque ripple, the fault-tolerant control method proposed in this paper not only takes the minimum copper loss as the constraint condition, but also injects the fifth harmonic current. The experimental result of current and torque is used to verify the accuracy of fault-tolerant control.

Theoretical study of micro-optical structure fabrication based on sample rotation and two-laser-beam interference

A method for fabricating a micro-optical structure based on sample rotation and two-laser-beam interference is proposed. The rotation process is analyzed using the coordinate transformation in matrix presentation and the theoretical expressions of the optical field distributions corresponding to different sample rotations. By rotating the samples and changing the laser wavelength, various special micro-optical structures can be obtained, such as equally spaced concentric rings and irregular trapezoidal lattices; these structures are demonstrated by simulating the corresponding optical field distributions. The proposed approach may be developed into a low-cost laser interference lithography technology for the fabrication of various micro-optical structures.

CORDIC algorithm based on FPGA

It is an important problem that we implement floating point trigonometric functions of high precision with suitable hardware cost for high performance in digit image processing. The coordinate rotational digital computer （CORDIC） arithmetic to is used to solve the above problem in this paper. In order to increase the speed of operation, it chooses the pipeline architecture. The results are disposed by IEEE-754 standard. The CORDIC architecture is modeled by using the verilog HDL and verified with MATLAB program and ModelSim 6.2SE tool. A 32 bits radix-2 CORDIC architecture was implemented on the available FPGA platform. The entire CORDIC architecture operated at 126.34 MHz of clock rate with a power consumption of 318.56 mW. Its theoretical background, procedures, simulation results and conclusions are presented in this paper.

Computer assessment of the composition of a generic wound by image processing

Aim:This paper addresses the assessment of the composition of a general wound,in terms of all identifiable categories of tissue and pigmentation in an attempt to improve accuracy in assessing and monitoring wound health.Materials and Methods:A knowledgebase of clusters was built into the hue,saturation and intensity(HSI)color space and then used for assessing wound composition.Based on the observation that the clusters are fairly distinct,two different algorithms,that is,Mahalanobis distance(MD)based and the rotated coordinate system(RCS)method,were used for classification.These methods exploit the shape,spread,and orientation of each cluster.Results:The clusters in the HSI color space,built from about 9,000(calibrated)pixels from 48 images of various wound beds,showed 8 fairly distinct regions.The inter-cluster distances were consistent with the visual appearance.The efficacy of the MD and RCS based methods in 120 experiments taken from a set of 15 test images(in terms of average percent-match)was found to be 91.55 and 93.71,respectively.Conclusion:Our investigations established eight categories of tissue and pigmentation in wound beds.These findings help to determine the stage of wound healing more accurately and comprehensively than typically permitted through use of the 4-color model reported in the literature for addressing specific wound types.