水下目标的激光声探测技术

高能脉冲激光聚焦于液体中,光击穿会伴随着光、声和空泡脉动等现象,其中击穿时等离子体膨胀产生的声和随后的空泡脉动产生的声统称为激光声。对产生的激光声信号进行分析,论证激光声信号应用于水下探测的可行性。设计激光声产生和测量分析系统,计算激光声信号的波束指向性、距离分辨力、噪声背景下和混响背景下的探测距离。结果表明,激光声声源在距离分辨力和声源级两方面满足对水下目标探测的要求。从理论推导和计算上初步证明了激光声信号可以应用于水下探测领域。     

激光雷达距离成像精度改进方法

成像激光雷达是一种有源成像系统,使用脉冲激光发射器和面阵接收器产生3D距离图像,具有广范围精度和宽范围门等特性。文中通过静态弥散宽度对图像模糊的影响分析,提出了时间分辨信号分布模型和改进范围精度分析方法。通过激光雷达测距系统试验分析表明,利用该模型得到的最佳静态弥散宽度对距离成像精度有显著影响,能够在白天强背景环境下对室内和室外的10 m和1700 m目标进行距离成像。在室内成像中,当静态弥散宽度为43.4μm时获得的最优测距精度为0.06 m,在室外成像中,获得了测距误差为0.25 m的分米级3D图像。该方法能够有效地提高激光雷达成像距离和成像精度,从而提高交通流测距和测速的精度。     

Percolation phenomenon in connected vehicle network through a multi-agent approach: Mobility benefits and market penetration

This paper presents an integrated multi-agent approach, coupled with percolation theory and network science, to measure the mobility impacts (i.e., mean travel time of the system) of connected vehicle (CVtio) network at varying levels of market penetration rate. We capture the characteristics of a CV network, i.e., node degree distribution, vehicular clustering, and giant component size to verify the existence of percolation phenomenon, and further connect the emergence of mobility benefits to the percolation phase transition in the CV network. We show the percolation phase transition properties to appear in a dynamic CV network with time-correlated link and node dynamics. An analytical framework was developed to evaluate the CV network attributes with varying market penetrations (MP) and connection ranges (CR) to identify percolation phenomenon in a mixed CV and Non-CV environment. In addition, a multi-agent CV simulation platform was created to further measure (1) how varying MPs and CRs affect the network-wide mobility measured by the mean travel time of the network; and (2) when percolation transition occurs in CV network to capture the critical MP and CR. Percolation phenomenon in CV network was further validated with the analytical assessments. The results show that (1) percolation phase transition phenomenon is a function of both market penetration and communication range; (2) percolation phase transitions in both mobility and CV network are highly correlated; (3) the application can reduce the average travel time of the system by up to 20% with reasonable market penetration and communication range; (4) critical market penetration is sensitive to communication range, and vice versa; (5) at least 70% of the CVs on the network are required to show in the same cluster for mobility benefits to appear; and (6) for high levels of MP or CR, a low probability of connectivity (PC) does not dramatically change the mean travel time. These results provide solid supports to create evidence-driven frameworks to guide future CV deployment and CV network analysis.     

合理确定大型开敞式码头前沿设计水深

合理确定的码头前沿设计水深,既能满足船舶安全作业的要求,又能使码头达到预期的运营效果。本文根据现行规范的要求,并结合实际工程项目,对大型开敞式码头前沿设计水深的计算进行了探讨。     

某型雷达侦察设备动态范围测试方法优化探讨

论文基于某型雷达侦察设备的系统灵敏度和动态范围的基本测试方法,提出了一种优化测试方案,进一步考虑了实际信号辐射到达测频前端和测向前端的功率情况,通过使用均衡器匹配方法,弥补了测频和测向前端的通道增益差异,较好地解决了该通道匹配问题。通过优化方案的模拟测试与指标转化结果,可以验证该优化方案更能等效代替大功率辐射源辐射法测试,为以后的整机系统调试、测试以及产品检验提供优化思路。     

东西方近程反导武器系统的设计思想及未来发展

分析了俄罗斯（前苏联）和西方各海军强国近程反导武器系统的设计思想与研制情况，简要介绍了东西方近程反导武器系统的发展水平和特点，对东西方海军强国一些有代表性的近程反导武器系统性能进行了对比，预测了近程反导武器系统的发展趋势及相应的对策。     

预警机引导导弹超视距攻击分析

水面舰艇编队自身雷达引导距离不能保障导弹的最大有效射程，而预警机作用距离可远大于导弹最大有效射程，且探测精度高，因此对预警机引导导弹进行超视距攻击进行分析。应用概率论方法，提出预警机引导导弹攻击概率评估模型，并运用Matlab仿真，对预警机引导导弹超视距攻击的概率进行评估。结果表明，运用预警机可大大提高导弹超视距攻击的概率，有利于水面舰艇编队先敌攻击，提高了水面舰艇编队的生存能力。     

舰载远程精确打击武器

介绍了以美国为代表的国外舰载远程精确打击武器的现状、发展背景、实现精确打击的手段以及对战术产生的影响；探讨了我国海军发展舰载远程精确打击武器的意义，并提出了发展远程精确打击武器的初步设想。     

Consumer valuation of changes in driving range: A meta-analysis

We perform a meta-analysis of studies investigating consumer preferences for electric and other alternative fuel vehicles (AFVs) to provide insights into the way driving range is traded off for capital costs. We find that consumers are willing to pay, on average, between 66 and 75 US$ for a 1-mile increase in driving range. Ceteris paribus, 100-mile-range cars have to be priced about 60% less than their conventional counterparts to become competitive. In line with intuition, but in contrast to most specifications employed in primary studies, we find that consumers’ marginal willingness to pay (WTP) decreases at a diminishing rate with increases in driving range. The variation in the WTP and compensating variation estimates among examined studies can be attributed to differences in the levels of driving range considered, in other elements of the study design and in the country of study. Our findings support stated preference literature’s conclusion that short driving range has been a major limitation to the large-scale adoption of battery electric vehicles (BEVs) and other AFVs, and that technological developments permitting longer driving ranges will, to some extent, facilitate their market penetration. We further propose that consumer valuation of driving range should not be examined in isolation from other attributes related to refuelling activities, such as refuelling duration and the coverage of refuelling infrastructure.     

对半幅双向行驶高速公路除雪问题的探索实践

石家庄-安阳高速公路首次在拓宽改建的半幅双向行驶的高速公路中进行机械化除雪,面对许多不利因素,认真分析研究,采用科学有效措施,成功完成了一年一度的除雪任务,探索了许多有益方法,总结了一些成功经验,供参考。