Analysis and implementation of cross sync period underwater acoustical positioning techniques for underwater targets

I.IlltroductionWhenanactiveunderwateracousticalpositioningsystemissearchingforanunderwatertarget,itisnecessaryforittocompleteatransmittingandreceivingcycIewithineachworkingperiodinordertofindoutthelocationofthetargetcorrectly.Forexample,whenanunder-wateracoustica1synchronouspositioningsystemistrackinganunderwatertargetwithagivensynchr0nizingperiod,thepropagati0ntimeofthepositioningsignaltravellingfr0mthetaJrgettothearrayofthesystemshouldbelessthanthesynchronizingperiod0therwisetargetdis-tance…     

水下运动目标长基线定位解算研究

水下运动目标长基线应答器导航定位方程是非线性的,其非线性解法是成熟的。本文所讨论的解算方法的优点是算法简便。本文讨论了该定位方程组的近似解法及对近似解法的理解,利用近似解将非线性定位方程组转化为易于求解的圆方程组求精确解。仿真研究和海上试验证明本文所介绍的解法是高精度的、简便的。     

金属线膨胀系数测定实验的改进及进一步研究

为了更好地研究金属线膨胀系数在一定温度区间的变化情况,并进一步研究在加热过程中,待测金属热应力、热应变的变化规律,本文在传统的蒸汽喷射加热仪的基础上,组合运用了粘滞系数实验、表面张力实验以及温度传感器实验中的部分实验仪器,测量并计算了相关的物理量,得到了相关性较理想的拟合直线,并通过对比实验进一步论述了该方法的可行性。     

多孔介质高温蓄热的热性能分析

高温蓄热是太阳能热发电、高温热利用中的重要组成部分。本文对基于多孔介质和熔融盐流体的高温蓄热过程进行了计算分析,对蓄热时间、流体进口温度、进口速度对斜温层温度分布的影响进行了分析。结果表明进口温度对斜温层厚度的影响较小,进口速度的增加会导致斜温层厚度的增加。同时对流体和多孔介质的温度差进行了分析,得到了应用于局部热平衡和非热平衡的雷诺数判据。     

PbTe纳米晶高压热电性能的研究

 利用自建的400 t四柱双缸液压机,研究了PbTe纳米晶在0~0.8 GPa压力范围内热电性能随压力的变化。实验结果表明：PbTe纳米晶电导率随压力的增加而增加,而热电动势随压力的增加而减小,两者随压力的变化具有可逆性;PbTe纳米晶具有极高的热电动势,在常压下达到565 μV/K,在0.8 GPa压力下,材料的电导率为常压下的4倍,热电动势仅降低20%,功率因子则达到常压下的3倍。研究表明,高压能显著提高PbTe纳米晶的热电性能。利用第一性原理计算了0.4~4.0 GPa压力范围内材料的简约费米能级,计算结果与实验结果相吻合。     

Reflection-Transmission Transition of Bright-Bright Solitons Collision in Two Species Condensates with Repulsive Interspecies Interactions

Considering repulsive interspecies interactions, we study the dynamical properties of bright-bright solitons in two species Bose-Einstein condensates by using a variational approach combined with numerical simulation. It is shown that the interactions between bright-bright solitons vary from repulsive to attractive interactions with the increasing their separating distances, and at equilibrium position the bright-bright solitons are localized. Interestingly, a transition from reflection- to transmission-collision is firstly observed, different from previous results of only reflection collision appearing there. These results will be helpful for the experimental manipulating such solitons.     

Ni13Pr3B2电子结构和磁性能第一性原理研

考虑电子自旋极化作用,本研究基于第一性原理的全电子投影缀加平面波赝势法理论,采用局域自旋密度近似LSDA,对Ni13Pr3B2金属间化合物进行结构优化,计算体系晶格常数,电子结构和磁性能。结果表明,Ni13 Pr 3B2为带隙很小的金属导体。LSDA近似下体系原子间存在复杂作用类型,Pr原子与近邻Ni、B原子以离子键作用为主,Ni原子与近邻Ni原子间表现共价作用情形。体系存在Pr -Ni铁磁耦合,总磁矩约2.80212μB,主要由Pr原子磁矩提供,自旋极化引起体系Pr-4f、Ni-3p、Pr-5p电子自旋劈裂为体系表现磁性的根本原因。     

Simulation study of neutrino nucleus cross section measurement in a segmented detector at a spallation neutron source

Knowledge of ν_e-Fe/Pb differential cross sections for ν_e energy below several tens of MeV scale is believed to be crucial in understanding supernova physics. In a segmented detector at a spallation neutron source, ν_e energy reconstructed from the electron range measurement is strongly affected because both multiple scattering and electromagnetic showers occur along the electron passage in target materials. In order to estimate these effects, a simulation study has been performed with a cube block model assuming perfect tracking precision. The energy spectrum distortion is observed to be proportional to the atomic number of the target material. Feasibility of unfolding the distorted ν_e energy spectrum is studied for both Fe and Pb. An evaluation of the statistical accuracy attainable is therefore provided for a segmented detector.     

载能团簇离子在物质中的能量损失

实验表明,团簇离子在物质中的能量损失并不等于各成分单独作用的总和,而是具有非线性效应．这种非线性效应与团簇离子的能量、团簇的种类和大小、团簇成分之间的空间关联程度以及作用物质的结构有关．对团簇作用的非线性效应研究对于了解团簇与物质相互作用的机制具有非常重要的理论意义．MeV能区的团簇离子在物质中的非线性电子能损和核能损方面的直接实验数据还相当缺乏,其理论模型也更待建立．评述了载能团簇离子在物质中的能量损失及测量方法．Fast ions deposit energy in matter through electronic and nuclear collision processes. The relaxation of the deposited energy induces emission of photons, electrons, ions, and neutral species from the target. Comparing with single incident ion, cluster induces many new phenomena: such as non-linear energy loss, non-linear emission of secondary ions, production of giant tracks and craters in various irradiated materials. These new phenomena induced by clusters are attributed to the vicinage effect ......     

氧离子与氦、氖原子碰撞中转移电离过程的研究

采用位置灵敏探测和散射离子-反冲离子飞行时间测量技术,测量了氧离子与氖和氦原子碰撞过程中转移电离截面与单电子俘获截面之比.通过比较发现测量结果与文献结果的趋势一致,并对测量结果进行了讨论.