基于时间反转的单水听器被动定位技术研究

对基于时间反转镜的单水听器的被动定位技术原理进行了阐述,并通过数值仿真对其被动定位性能做出了分析。通过分析得知基于单声压水听器的时间反转镜定位方法可准确估计目标的距离与深度。同时对单矢量水听器与单声压水听器的定位性能做了对比,并给出了对比结果。     

新型水下高效毁伤战斗部技术发展趋势

就水下战斗部在现代海战中的作用进行了阐述,并对水下战斗部的现状进行了描述,重点针对水下战斗部起爆保险方式、起爆方式、装药品种、装药结构及毁伤方式的发展方向进行了探讨,指出了未来水下战斗部高效毁伤战斗力的发展趋势。     

亚太地区自导水雷的发展

自导水雷作为一个非常重要的雷种,在亚太发达海军武器序列中一直占据着重要位置。现代自导水雷,不仅有反潜型,而且还研制出了反舰型。     

水下航行器大侧斜对转桨水动力性能计算

对转桨具有效率高的特点,大侧斜桨具有噪声低的特点。因此,大侧斜对转螺旋桨通过合理设计,能够兼备两者优势于一体,其水动力性能计算是设计中的一个关键问题。本文基于不可压缩流体"雷诺时均Navier-Stokes方程+RSM湍流模型",采用多重参考系模型处理多旋转区域耦合问题,仿真计算了螺旋桨的稳态流场,得到推力、扭矩、航速及效率等相关参数信息。相对常规对转桨而言,大侧斜对转桨的水动力性能更加优越,适用于水下航行器的推进器领域。     

Macroscopic synthesis of onion-like graphitic particles

In this paper, we present a method for macroscopic synthesis of onion-like graphitic particles, which may be used to study physical properties. This method is based on annealing carbon nanotubes under high pressure. By transmission electron microscopy (TEM), the microstructure of carbon nanotubes is found to transform into quasi-spherical graphitic structures when the sample has been treated at 770 °C and 950 °C under 5.5 GPa. The high pressure assumes an important role in this transformation.     

The theoretical simulation of the effect of solid–liquid contact angle on the critical heat flux of saturated water jet boiling on stagnation zone

A theoretical simulation was carried out for predicting the critical heat flux (CHF) of convective boiling for a round saturated water jet impingement on the stagnation zone of a hot surface. The study was focused on the effect of the solid–liquid contact angle on the CHF. A theoretical model based on the Long wave instability was applied to calculate the maximum liquid sub-film thickness under boiling bubbles and finally a semi-empirical and semi-theoretical correlation was proposed by combining the simulated calculation and the experimental data from the common metal heating surface. The correlation revealed the comprehensive effects of solid–liquid contact angles, jet velocity and jet diameter on the CHF and agreed well with the experimental data proposed by authors in the previous study.     

对抗图像旋转的手指静脉身份识别新算法的设计

为了克服图像旋转对手指静脉身份识别系统正确率的影响,在图像预处理部分提出一种基于手指指尖点的旋转定位方法,改进了基于方向模板和局部动态阈值分割提取静脉特征的方法并用改进Hausdorff距离（MHD）距离进行匹配验证。实验结果表明,同一根手指的图片在平面偏移角度小于20°时,可以达到0.75%的等误率,正确识别率达97.25%,而且整个处理过程在VC++6.0上面执行耗时仅为161.6949ms,系统具有很好的实时性能,对实际手指静脉身份识别产品的开发具有一定的现实意义。     

Characterization of aluminum-doped zinc oxide thin films by RF magnetron sputtering at different substrate temperature and sputtering power

In this study, transparent conductive Al doped zinc oxide (ZnO: Al, AZO) thin films with a thickness of 40 nm were prepared on the Corning glass substrate by radio frequency magnetron sputtering. The properties of the AZO thin films are investigated at different substrate temperatures (from 27 to 150 °C) and sputtering power (from 150 to 250 W). The structural, optical and electrical properties of the AZO thin films were investigated. The optical transmittance of about 78 % (at 415 nm)–92.5 % (at 630 nm) in the visible range and the electrical resistivity of 7 × 10^?4 Ω-cm (175.2 Ω/sq) were obtained at sputtering power of 250 W and substrate temperature of 70 °C. The observed property of the AZO thin films is suitable for transparent conductive electrode applications.     

一种简化的平面阵波束形成方法

0引言波束形成技术是将一个多元阵经适当处理使其对某些空间方向的声波具有所需响应的方法。波束形成技术系统是现代声纳的核心部件,是声纳具有良好的战术、技术性能的基础[1]。平面阵是声纳系统常用的基阵,可以实现对目标的全空间定向,但平面阵二维波束形成运算量较大,在某些小平台上,由于功耗和系统复杂性的限制,希望能在性能没有显著降低的前提下进行简化处理。本文把平面     

Determination of the operating range of CO2 conversion and syngas production in dry auto-thermal reforming

A porous medium-catalyst hybrid reformer for CO₂ conversion by dry auto-thermal reforming (DATR) was investigated in this study, and its operating range was discovered. The hybrid design was used to enhance the oxidative heat release by internal heat recirculation during exothermic reaction conditions, thereby increasing the CO₂ conversion efficiency. The experimental results show that the CO₂ conversion could be enhanced with higher catalyst inlet temperatures. The examination of the operating range of DATR showed that the CO₂ conversion efficiency increased at higher reaction temperatures and CO₂/CH₄ ratios (≧1). Moreover, DATR in high temperature conditions must be carried out with high O₂/CH₄ ratios. Under these conditions of high oxygen content, CO₂ generation and reduction reactions occur simultaneously. Overall, optimal CO₂ conversion can be obtained with an O₂/CO₂ ratio of approximately 0.5. At these conditions, CO₂ conversion efficiency can reach approximately 13% without external heat addition.