β—BBO晶体的电光性能

用干涉法测量了β－ＢＢＯ晶体的电光系数：γ２２＝２．６，γ３３＝０．２３，γ３１＝０．２５，γ５１＝－３．５×１０－１２ｍ／Ｖ。结果表明如果在Ｙ方向加电场，Ｚ方向通光，β—ＢＢＯ晶体可能制作成有应用价值的光开关。     

一种双光束自动测试光栅绝对与相对光谱衍射效率的原理性方案

提出了一种快速自动测试光栅光谱衍射效率的新方法。重点推导了测试平面光栅绝对光谱衍射效率与相对光谱衍射效率公式，介绍了双光束高精度自动测试光栅光谱衍射效率曲线的基本原理、方案与方法，并分析了测试精度。研究表明，本方案的测试速度和精度均比一般测试方法提高一倍，并能有效地消除光源波动对测量结果的影响，测量误差小于５×１０－３。     

The feature-based posterior crown design in a dental CAD/CAM system

This paper presents a newly developed CAD approach for a quick and accurate design of a dental posterior prosthesis. The approach arises from the basic idea that every human tooth has its own specific features. Based upon the features of the standard posterior tooth, the initial data containing the defined feature points are firstly acquired from the scanned points of the standard tooth. The standard prosthetic profile is thereby formulated using the bicubic Nurbs surface fitting technique. This profile has the two functions of possessing the same features with the patient’s missing posterior tooth, and the adjustability with the feature points and the defined B-spline profile feature curves. For the purpose of the adjustment of the established model, the global and occlusal feature curves are proposed considering the individual patient’s original information. According to these curves, the corresponding standard prosthetic profile is locally adjusted to meet the fit of the global size and occlusal surface. Finally, a close and continuous profile of a posterior crown is generated. Using this design, a posterior prosthesis is successfully manufactured in the computer-aided machining process.     

岩溶地区设计洪水计算的探讨

岩溶地区溶洞形状千姿百态，对洪水的影响程度各不相同，如何考虑其影响，在目前的水利水电工程设计规范中没有明确规定。贵州省是世界上典型的岩溶地貌地区之一，根据在贵州省水利水电工程设计的实践，总结摸索出针对不同溶洞状况、集水状况和水文站布设情况的设计洪水计算方法。在可确定岩溶集水面积条件下的方法有调洪演算法、溶洞削减法、叠加合成法和统一处理法；不能确定岩溶集水面积条件下的方法有流量法、地区综合法、统一处理法等。     

Network traffic prediction based on a new time series model

Fast and accurate methods for predicting traffic properties and trend are essential for dynamic network resource management and congestion control. With the aim of performing online and feasible prediction of network traffic, this paper proposes a novel time series model, named adaptive autoregressive (AAR). This model is built upon an adaptive memory‐shortening technique and an adaptive‐order selection method originally developed by this study. Compared to the conventional one‐step ahead prediction using traditional Box–Jenkins time series models (e.g. AR, MA, ARMA, ARIMA and ARFIMA), performance results obtained from actual Internet traffic traces have demonstrated that the proposed AAR model is able to support online prediction of dynamic network traffic with reasonable accuracy and relatively low computation complexity. Copyright © 2005 John Wiley & Sons, Ltd.     

多属性神经网络地震反演在NB油田水平井钻探中的应用

NB油田位于渤海海域,为新近系河流相稠油油田,储层横向分布不稳定,砂体厚度薄、连通性较差,油水关系复杂,开发设计部署了大量水平井。选择神经网络反演方法,建立地震属性与储层参数的非线性关系,进而根据其关系反演得到储层参数数据体,利用该数据体沿层切片提取储层预测信息,研究储层发育规律,指导该油田水平井的部署和钻探,取得了较好的效果,降低了钻探风险。用神经网络地震反演方法进行储层预测研究,指导水平井钻探,在渤海海域尚属首次。     

液态混合有机标准物质研究

本研究采用重量法配制有机液态混合标样 ,并对配制方法、混合标样的均匀性、稳定性及影响不确定度的因素进行了研究 ,并用气相色谱法进行了比对分析。经稳定性监测 ,稳定度大于等于一年 ,不确定度小于± 2 %。     

一种适用于有限长度混合相位未知脉冲的最小平方反褶积新方法

普通的最小平方反褶积只有在子波为最小相位脉冲和反射序列为白噪声的假设下才是成立的,而对于混合相位未知脉冲来说,这种最小平方反褶积就不再适用了。本文提出一种适合于有限长度混合相位未知脉冲的最小平方反褶积方法。运用此法只需预先估计一个混合相位子波的长度。合成数据的试验结果表明,该方法有较好的效果,且对预先估计出的子波长度不敏感。文中还证明混合相位未知脉冲最小平方反褶积等效于一种有间隙的平滑误差滤波器的作用,而这种有间隙的平滑误差滤波又可分解为一个前向多步预测误差滤波与一个后向多步预测误差滤波之和。可以预计这种新的反滤积方法将在地震数据处理中得到有效的应用。     

Optical Endless Polarization Stabilization at 9 krad/s With FPGA-Based Controller

We demonstrate endless polarization stabilization with a control speed of up to 9 krad/s, over random Poincare sphere trajectories. These are in total >35 Mrad long, are composed in particular of difficult-to-track circles with all radii and orientations, and thereby include all possible worst cases. The maximum polarization mismatch and relative intensity errors are 0.13 rad and 0.43%, respectively. The controller runs on a field-programmable gate array and uses a commercial multistage LiNbO₃ polarization transformer as the control device.     

La doping effects on intergrowth Bi2WO6–Bi3TiNbO9 ferroelectrics

La doping effects on intergrowth Bi₂WO₆–Bi₃TiNbO₉ ferroelectric ceramics were studied by X-ray diffraction, electron probe microanalysis and dielectric spectroscopy. It was found that the La³⁺ distribution, ferroelectric phase transition and dielectric relaxation behavior are apparently affected by La doping. With increasing La³⁺ content, the site of dopant ion varies, the grain growth of Bi₅TiNbWO₁₅ is restrained, the Curie temperature is reduced and broadened. Furthermore, two dielectric relaxation loss peaks were observed both in temperature and frequency spectra. The calculated relaxation parameters revealed the oxygen vacancy related to the relaxation process.