LDPC码的稳定中断分析

对于一个给定的信道和一个特定的ldpc码族,针对由密度进化的不稳定性而造成的稳定中断事件,本文通过研究了BEC和AWGN信道中的稳定中断概率并确切表达了在块衰弱信道中的稳定中断概率,其仿真过程给出了在删除信道中容量逼近系统是怎样跳开了在块衰弱信道中的中断限制。     

激光斜入射条件下“猫眼”效应的实验研究

"猫眼"目标回波功率是激光主动探测系统的重要指标,可用来评估光电装备"猫眼"效应的强弱,并为探测器的优化设计提供参考。依据所建立的斜入射条件下"猫眼"目标回波功率数学模型,仿真分析了入射角对"猫眼"目标回波功率的影响,利用搭建的激光主动探测系统对典型"猫眼"目标进行了实验研究,理论仿真结果与实验结果表明,激光在有限斜入射条件下,"猫眼"目标回波功率将随入射角的增大而迅速下降,并很快湮没于噪声之中。这为进一步研究基于"猫眼"效应的激光主动探测适用条件提供必要的实验依据。     

VOx薄膜的制备、电阻-温度特性及结构研究

VO2是一种热致相变材料.发生相变时,VO2的电阻、红外光透过率、反射率都会发生显著变化.采用直流反应磁控溅射法,通过改变氧氩比(O2:Ar)、工作气压、衬底温度等制备工艺参数,研究了工艺参数对VOx薄膜的结构、电阻-温度性能的影响.结果表明,当氧氩比为1.0:15、工作气压为2.0Pa时,制备的薄膜中VO2的含量较多;衬底温度为250℃时,制备的VOx薄膜的电阻一温度突变性能最佳.     

机组初参数的热经济性模型研究及其应用

以汽轮机功率方程为基础,应用偏微分理论,根据汽轮机变工况的基本原理以及各参数之间的变化关系,经过严格的数学推导,得到了主蒸汽参数变化对机组热经济性影响的数学计算模型。此外,还以N600-16.7/537/537-I型汽轮机的运行数据为例,对模型进行验证。计算实例表明:该模型具有计算结果准确、使用方便、通用性强等特点,适用于工程实际应用,对机组性能监测和优化运行有重要意义。     

NUMERICAL INVESTIGATION ON THE HYDRODYNAMIC PERFORMANCES OF A NEW SPAR CONCEPT

Recently, the spar platform concept develops quickly in the offshore oil and gas exploitations, especially in deep and ultra-deep water, owing to its benign motion performance, excellent stability and adaptation to wide range of water depth. Many new spar concepts have been put forward with the purpose of reducing fabrication difficulty and cost, while meeting the requirements of exploitation in the meantime. Based on the aims mentioned above, a new spar concept was presented in this article and its hydrodynamics both in operating and survival conditions was studied by means of numerical simulation. Basic model tests were also conducted to calibrate the numerical approach. Following aspects are highlighted: (1) new spar concept, (2) global performance of the spar concept and (3) mooring line analysis.     

水压图教学实验台的研制及实验分析

介绍了水压图教学实验台的构成,通过调节阀门进行了不同水力工况下同程式和异程式管网的水压图实验。     

三峡船闸四级运行方式优化研究

针对三峡船闸在四级运行方式下,二闸室充水过程中一闸室待闸条件不佳和充水时间超过设计允许值的问题,采用在二闸室充水前关闭一闸首人字门+快速开启阀门的运行方式,并在原型上进行了调试优化.水力学观测、实船试验及分析表明,这一运行方式从根本上改善了一闸室的待闸条件,显著提高了船舶待闸的安全性,并使一、二闸室充水时间缩短到与后续闸室一致,满足了不大于12 min的设计要求,彻底改变了四级运行方式下二闸室充水过程成为延长船舶过闸时间关键的现状,可使日通过闸次由一闸室不待闸的13～14.5次提高到18.7～22.1次.     

Fluid Flow and Mixing in Non-Isothermal Water Model of Continuous Casting Tundish

Fluid flow and mixing of molten steel in a twin-slab-strand continuous casting tundish were investigated using a mixing model under non-isothermal conditions.This model led to a set of ordinary differential equations that were solved with a Runge-Kutta algorithm.Steady state water modeling was carried out under non-isothermal conditions.Experimental data obtained from the water model were used to calibrate the mixing model.Owing to the presence of a mixed convection in the non-isothermal conditions,a channelizing flow would be created in the fluid inside the tundish.A mixing model was designed that was capable of predicting RTD（residence time distribution）curves for different cases in non-isothermal conditions.The relationship between RTD parameters and the Tu（tundish Richardson number）was obtained for various cases under non-isothermal conditions.The results show that the RTD parameters were completely different under isothermal and non-isothermal conditions.The comparison of the RTD curves between the isothermal and non-isothermal conditions presents that the extent of mixing in the tundish in non-isothermal conditions is lower than the mixing extent in isothermal conditions.     

塔里木盆地卡塔克2、3、4区块烃源条件

根据近年的钻井、测井及地化分析资料对卡塔克2、3、4区块烃源条件重新评价，认为该区块发育有中下寒武统、上寒武统一下奥陶统和中上奥陶统三个烃源岩层段，中上奥陶统灰泥丘和暗色泥岩为本区主要烃源岩。综合评价，卡塔克2、3、4区块烃源充足，该区油气勘探前景较好。     

四川盆地下二叠统,上三叠统水动力场与天然气保存

下二叠统和上三叠统储集层是四川盆地油气主力产层。在对其水动力场控制因素分析研究的基础上，对实测地层压力资料进行数据处理，分别建立了Ｐ１和Ｔ３地层压力预测模型。地层埋深，孔隙度，构造抬升率和褶皱强度等为现今水动力场的主要控制因素，其中地层埋深对地层压力的影响最大。