对提高放射性同位素测量精度的研究

为评价放射性同位素测量的精度 ,对美国BeckmanLS 65 0 0ScintillationSystem的单标DPM(SLDPM)和AUTODPM两种猝灭校正方法进行了比较。结果显示 ,SLDPM的猝灭校正范围宽(校正范围由校正曲线决定 ) ,猝灭校正精度高 ,并且可以用于测试双标或三标的样品。使用AU TODPM猝灭校正方法进行测试 ,对于低能β射线3H ,在 90 <H#<1 93的范围内 ,能够达到要求的校正精度 ;当H#值在 0～ 90时 ,其校正精度不高 ;当H#值大于 1 93时 ,仪器无法进行猝灭校正 ;对于较高能量的 β射线14 C ,其猝灭校正范围与单标DPM猝灭校正方法的猝灭校正范围基本相同。但是 ,前者测试的相对误差比后者的大 ,此种猝灭校正方法只能用于测试单标样品。可见对于仪器内存猝灭校正曲线的放射性同位素 ,如3H、14 C等 ,一般使用单标DPM猝灭校正方法测试。对于35S、4 5Ca、86 Rb等仪器没有内存猝灭校正曲线的放射性同位素 ,其射线能量类似或大于14 C的均可使用AUTODPM猝灭校正方法进行测量。

Complex seismic wavefi eld interpolation based on the Bregman iteration method in the sparse transform domain

In seismic prospecting, fi eld conditions and other factors hamper the recording of the complete seismic wavefi eld; thus, data interpolation is critical in seismic data processing. Especially, in complex conditions, prestack missing data affect the subsequent highprecision data processing workfl ow. Compressive sensing is an effective strategy for seismic data interpolation by optimally representing the complex seismic wavefi eld and using fast and accurate iterative algorithms. The seislet transform is a sparse multiscale transform well suited for representing the seismic wavefield, as it can effectively compress seismic events. Furthermore, the Bregman iterative algorithm is an efficient algorithm for sparse representation in compressive sensing. Seismic data interpolation methods can be developed by combining seismic dynamic prediction, image transform, and compressive sensing. In this study, we link seismic data interpolation and constrained optimization. We selected the OC-seislet sparse transform to represent complex wavefields and used the Bregman iteration method to solve the hybrid norm inverse problem under the compressed sensing framework. In addition, we used an H-curve method to choose the threshold parameter in the Bregman iteration method. Thus, we achieved fast and accurate reconstruction of the seismic wavefi eld. Model and fi eld data tests demonstrate that the Bregman iteration method based on the H-curve norm in the sparse transform domain can effectively reconstruct missing complex wavefi eld data.

A Fast Half-Pixel Motion Estimation Algorithm and Efficient Interpolation Hardware Architecture Unit for H.264/AVC

In this paper, a fast half-pixel motion estimation algorithm and its corresponding hardware architecture is presented. Unlike three steps are needed in typical half-pixel motion estimation algorithm, the presented algorithm needs only two steps to obtain all the interpolated pixels of an entire 8x8 block. The proposed architecture works in a parallel way and is simulated by Modelsirn 6.5 SE, synthesized to the Xilinx Virtex4 XC4VLX15 FPGA device. The implementation results show that this architecture can achieve 190 MHz and 10 clock cycles are reduced to complete the entire interpolation process when compared with typical half-pixel interpolation, which meets the requirements of real-time application for very high defination videos.

Network-aware perceptual error concealment method for H.264 video with side information

In order to improve the video quality of transmission with data loss,a spatial and temporal error concealment method was proposed,which considered both the state information of the network and the perceptual weight of the video content.The proposed method dynamically changed the reliability weight of the neighboring macroblock,which was used to conceal the lost macroblocks according to the packet loss rate of the current channel state.The perceptual weight map was utilized as side information to do weighted pixel interpolation and side-match based motion compensation for spatial and temporal error concealment,respectively.And the perceptual weight of the neighboring macroblocks was adaptively modified according to the perceptual weight of the lost macroblocks.Compared with the method used in H.264 joint model,experiment results show that the proposed method performs well both in subjective video quality and objective video quality,and increases the average peak signal-to-noise ratio(PSNR) of the whole frame by about 0.4 dB when the video bitstreams are transmitted with packets loss.

Research and Design of Coordinated Control Strategy for Smart Electromechanical Actuator System

In order to improve the frequency response and anti-interference characteristics of the smart electromechanical actuator(EMA)system,and aiming at the force fighting problem when multiple actuators work synchronously,a multi input multi output(MIMO)position difference cross coupling control coordinated strategy based on double‑closed-loop load feedforward control is proposed and designed.In this strategy,the singular value method of return difference matrix is used to design the parameter range that meets the requirements of system stability margin,and the sensitivity function and the H_(∞)norm theory are used to design and determine the optimal solution in the obtained parameter stability region,so that the multi actuator system has excellent synchronization,stability and anti-interference.At the same time,the mathematical model of the integrated smart EMA system is established.According to the requirements of point-to-point control,the controller of double-loop control and load feedforward compensation is determined and designed to improve the frequency response and anti-interference ability of single actuator.Finally,the 270 V high-voltage smart EMA system experimental platform is built,and the frequency response,load feedforward compensation and coordinated control experiments are carried out to verify the correctness of the position difference cross coupling control strategy and the rationality of the parameter design,so that the system can reach the servo control indexes of bandwidth 6 Hz,the maximum output force 20000 N and the synchronization error≤0.1 mm,which effectively solves the problem of force fighting.

Complementarity Problems for Multivalued Non-Monotone Operators in Banach Spaces

We utilize Park＇s maximal element theorem in H-space to prove the existence theorems of solutions of the complementarity problems for multivalued non-monotone operators in Banach spaces.

Detection of Charged Higgs Bosons in e^+e^-(γγ)→tφ^- Production at the ILC

Abstract In the context of the left-right twin Higgs （LRTH） model, we have studied the charged Higgs bosons production processes e＋e-（γγ） →tbФ- at the International Linear Collider （ILC）. It is found that the cross sections of these two processes could reach a few Fo with reasonable parameter values. With the yearly integrated luminosity of L 500 fb-1 expected at the ILC, one could collect hundreds up to thousands of charged ttiggs events via these two processes. Therefore, our researches in this paper can help us search for charged Higgs bosons, and furthermore, to test the LRTH model.