基于连续HMM的汉语数码语音识别系统

探讨了连续隐马尔可夫模型的基本原理及其在汉语数码语音识别中的应用,实现了一个汉语数码语音识别系统,其正确识别率达到99%以上。     

资料同化中的数字滤波弱约束试验及分析

气象数值预报中,由于分析过程引入初始非平衡,从而引起虚假快波振荡,重力波控制弱约束把资料分析过程和初始化过程结合在一起,通过数字滤波弱约束在极小化过程中实现对分析场的平衡约束,克服非平衡问题. 以2008年初的一次南方雨雪天气为研究个例,进行了数字滤波弱约束的同化试验和预报试验,结果表明,数字滤波弱约束4D-Var能充分控制快波振荡的出现和初始调整现象,使得到的分析场不仅能更好的逼近观测,而且能更好地与模式动力相协调. 预报检验的结果表明,在同化过程中施加数字滤波弱约束,能有效滤除由于地形或观测资料等因素 关键词： 变分同化 初始非平衡 数字滤波 弱约束     

Theoretical study on structures of Ga3N, GaN3, Ga3N2 and Ga2N3 clusters

The structures of Ga_3N, GaN_3, Ga_3N_2 and Ga_2N_3 clusters are studied using the full-potential linear-muffin-tin-orbital molecular dynamics (FP-LMTO MD) method. Four structures for Ga_3 N, five structures for GaN_3, nine structures for Ga_3N_2 and nine structures for Ga_2N_3 have been obtained. The most stable structures of these clusters are planar ones. A strong dominance of the N－-N bond over the Ga－-N and Ga－-Ga bonds appears to control the structural skeletons, supporting the previous result obtained by Kandalam and co-workers. The most stable structures of these small GaN clusters displayed semiconductor-like properties through the calculation of the HOMO－LUMO gaps.     

Effect of Reactor Pressure on Qualities of GaN Layers Grown by Hydride Vapour Phase Epitaxy

The influence of reactor pressure on GaN layers grown by hydride vapour phase epitaxy （HVPE） is investigated. By decreasing the reactor pressure from0. 7 to 0.5 mm, the GaN layer growth mode changes from the island-like one to the step flow. The improvements in structural and optical properties and surface morphology of GaN layers are observed in the step flow growth mode. The results clearly indicate that the reactor pressure, similarly to the growth temperature, is One of the important parameters to influence the qualities of GaN epilayers grown by HVPE, due to the change of growth mode.     

蓄能型液体除湿冷却空调系统的建立与实验研究

本文提出了一种蓄能型液体除湿蒸发冷却空调系统的设计方案,并基于此方案搭建了一个制冷量为3 kW的蓄能型液体除湿蒸发冷却空调系统实验台。通过电加热器模拟60~80℃的低品位热源(太阳能、发动机排气余热、工业余热等),以LiCl水溶液作为除湿溶液,主要研究了在系统稳定运行时,各环境参数对此除湿蒸发冷却空调系统性能系数COP的影响情况。     

非对称核物质不可压缩系数的微观计算(英文)

在带微观三体力的Brueckner-Hartree-Fock方法下研究了非对称核物质的不可压缩系数,得到了不可压缩系数的同位旋以及密度依赖, 并做了进一步的讨论。在一定密度下,不可压缩系数作为同位旋非对称度的函数随同位旋单调递增。 预测了非对称核物质在平衡态的同位旋依赖性质并与其他理论方法做了比较。 We have investigated the incompressibility of asymmetric nuclear matter within the Brueckner Hartree Fock approach extended to include a microscopic three body force. The isospin dependence and density dependence of the nuclear incompressibility have been obtained and discussed. It is shown that the incompressibility at a fixed density increases monotonically as a function of isospin asymmetry. The isospin asymmetry dependence of the equilibrium properties of asymmetric nuclear matter is also predicted and compared with the results of other theoretical approaches.     

全合成法光纤预制棒制造研究

介绍了一种全新的全合成法G.655和G.656光纤制造工艺,详细分析了该工艺中芯层折射率差Δ0、芯层厚度a、第二包层的折射率差Δ2、第二包层的厚度c2等结构参量与光纤光学性能的关系.结果表明,制造该两种光纤时,Δ0应在0.012 0～0.015 5之间,Δ2应在0.014 0～0.023 0之间,a应在2.8～3.2 μm之间,c2应在满足截止波长的要求下尽可能小.     

基于光谱分析的重载车辆变速箱可靠性评估方法研究

润滑油光谱分析是变速箱磨损状态监测的重要手段。以某重载车辆变速箱台架试验中润滑油原子发射光谱分析得到的元素成分含量检测数据为基础,通过相关性分析和磨损机理分析确定了能够反映整机磨损状态和失效特点的金属元素,并对补油、换油后的光谱检测数据进行了修正,将变速箱试验过程中特征金属元素的含量随试验时间的变化规律表示为线性函数的形式。然后,综合考虑检测数据的时序规律与离散性,利用不同时刻光谱检测数据的正态分布均值和标准差进行变速箱可靠性评估,进一步讨论了失效阈值对可靠性评估结果的影响。研究表明,重载车辆变速箱润滑油中的Cu元素浓度与其他金属元素浓度的相关性较高、绝对值较大,既能够反映变速箱整体磨损状态,又便于检测,利用多个试验样本的润滑油Cu元素浓度光谱检测时序数据,可以对重载车辆变速箱进行可靠性评估;若失效阈值取定值,则失效阈值越大,同一时刻变速箱的可靠度越高;若失效阈值取随机分布,则失效阈值的离散度越大,可靠度随时间延长而降低的趋势越缓慢。当可靠度R大于0.9时,失效阈值的均值对可靠性评估结果的影响十分显著,同一时刻变速箱的可靠度随失效阈值标准差的增大而降低。将光谱分析与概率统计学结合进行变速箱可靠性评估方法研究,扩展了光谱分析技术的应用范围,具有创新性。     

Isoscalar Giant Monopole Resonance in Relativistic Continuum Random Phase Approximation

The isoscalar giant monopole resonance （ISGMR） in nuclei is studied in the framework of a fully consistent relativistic continuum random phase approximation （RCRPA）. In this method the contribution of the continuum spectrum to nuclear excitations is treated exactly by the single particle Green＇s function technique. The negative energy states in the Dirac sea are also included in the single particle Green＇s function in the no-sea approximation. The single particle Green＇s function is calculated numerically by a proper product of the regular and irregular solutions of the Dirac equation. The strength distributions in the RCRPA calculations, the inverse energyweighted sum rule m-1 and the centroid energy of the ISGMR in ^120Sn and ^208Pb are analysed. Numerical results of the RCRPA are checked with the constrained relativistic mean field model and relativistic random phase approximation with a discretized spectrum in the continuum. Good agreement between them is achieved.     

多路角度复用体全息三维显示技术

为满足高分辨率真三维大数据显示的空间带宽积要求,提出一种基于多通道角度复用模式的体全息三维显示技术。通过对三维场景进行波前编码,获得相位计算全息图,并将计算全息图依次按照不同角度复用记录到掺杂金纳米颗粒体全息光致聚合物材料的同一区域,获得复用体全息图,再现时可以在不同角度观察三维场景。在体全息三维显示实验系统中,实现体全息材料记录区域的单点像素总数为120×1 920×1 080,显示的空间带宽积达到了2.5×108,相对于空间光调制器显示提升了120倍。