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471.
为了提高无人车在夜间情况下对周围环境的物体识别能力,提出一种基于多视角通道融合网络的无人车夜间三维目标检测方法。引入多传感器融合的思想,在红外图像的基础上加入激光雷达点云进行目标检测。通过对激光雷达点云进行编码变换成鸟瞰图形式和前视图形式,与红外图像组成多视角通道,各通道信息之间融合互补,从而提高夜间无人车对周围物体的识别能力。该网络将红外图像与激光雷达点云作为网络的输入,网络通过特征提取层、候选区域层和通道融合层准确地回归检测出目标的位置以及所属的类别。实验结果表明,该方法能够提高无人车在夜间的物体识别能力,在实验室的测试数据中准确率达到90%,速度0.43 s/帧,达到了实际应用要求。 相似文献
472.
对乙烯、共轭二烯、叠烯、羰基、烯胺、亚胺双键中的sp2杂化碳、氧、氮原子以及双键相连的质子或碳原子化学位移实验数据的分析表明, 目前化学位移理论中所采用的π-键在磁场中产生环流的假说与实验结果有严重矛盾. 核周电子云变形模型可较好地解决这些矛盾. 相似文献
473.
474.
基于改进迭代最近点算法的两视角激光雷达数据配准 总被引:1,自引:0,他引:1
两视角激光雷达数据配准是空地探测遮蔽目标研究领域中的一项重要内容,迭代最近点(ICP)算法为其提供了理论基础,但遮蔽条件下激光雷达数据的复杂性使ICP算法在对应点确定上面临很大困难。在分析ICP算法基本原理和遮蔽条件下激光雷达数据特点的基础上,从控制点选择、对应点匹配和伪点对剔除三个方面给出了ICP算法的具体应用策略和改进措施,并提出一种基于固定-自适应重叠率的伪点对剔除方法。详细阐述了基于改进ICP算法的两视角激光雷达数据配准的具体步骤,并进行了实验验证。实验结果表明:改进后的ICP算法能够有效实现了遮蔽条件下的激光雷达数据配准,且与其他算法相比,具有较强的稳建性和较高的配准精度。 相似文献
475.
Suwa K. Yamamoto K. Akashi M. Takano K. Tanaka N. Kunugi S. 《Colloid and polymer science》1998,276(6):529-533
We examined the effects of salt on the lower critical solution temperature (LCST) and lower critical solution pressure (LCSP)
of aqueous solutions of poly (N-vinylisobutyramide), polyNVIBA, and compared them with those on poly(N-isopropylacrylamide), polyNIPAAm. We found that the addition of salt (such as Na2SO4, NaCl, or KCl) decreased the LCST of aqueous polyNVIBA from 45 °C to below 20 °C, almost linearly with the salt concentrations
and dependent on the type of salt. We observed a similar concentration-dependent decrease in LCST for polyNIPAAm. When KI
or NaSCN was added to each aqueous polymer solution, some smaller increases in LCST were observed at relatively low salt concentrations;
higher concentrations of salt gave an almost linear decrease in LCST. As for LCSP, the addition of most types of salt lowered
the transition pressure, but the effects were much more dependent on the type and the valence of the salt (especially of anion)
in both polymers. Salt with divalent anion showed a larger decrease in LCSP, but those with mono valent anion showed a relatively
small decrease, even showed a slight increase at lower salt concentrations in the case of polyNVIBA. Salt with I- or SCN- showed evident increases in LCSP up to 1 M and was maintained higher than the control even at 2 M. We discuss the interactions
of the amide group in the side chains of polymers and water and their perturbation by ions.
Received: 13 November 1997 Accepted: 22 January 1998 相似文献
476.
Hiroaki Shimomoto Shokyoku Kanaoka Sadahito Aoshima 《Journal of polymer science. Part A, Polymer chemistry》2012,50(19):4137-4144
A series of poly(2‐methoxyethyl vinyl ether)s with narrow molecular weight distributions and with perfectly defined end groups of varying hydrophobicities was successfully synthesized by base‐assisting living cationic polymerization. The end group was shown to greatly affect the temperature‐induced phase separation behavior of aqueous solutions (lower critical solution temperature‐type phase separation) or organic solutions (upper critical solution temperature‐type phase separation) of the polymers. The cloud points were also influenced largely by the molecular weight and concentration of the polymer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
477.
The operation of a stand‐alone photovoltaic (PV) system ultimately aims for the optimization of its energy storage. We present a mathematical model for cost‐effective control of a stand‐alone system based on a PV panel equipped with an angle adjustment device. The model is based on viscosity solutions to partial differential equations, which serve as a new and mathematically rigorous tool for modeling, analyzing, and controlling PV systems. We formulate a stochastic optimal switching problem of the panel angle, which is here a binary variable to be dynamically controlled under stochastic weather condition. The stochasticity comes from cloud cover dynamics, which is modeled with a nonlinear stochastic differential equation. In finding the optimal control policy of the panel angle, switching the angle is subject to impulsive cost and reduces to solving a system of Hamilton‐Jacobi‐Bellman quasi‐variational inequalities (HJBQVIs). We show that the stochastic differential equation is well posed and that the HJBQVIs admit a unique viscosity solution. In addition, a finite‐difference scheme is proposed for the numerical discretization of HJBQVIs. A demonstrative computational example of the HJBQVIs, with emphasis on a stand‐alone experimental system, is finally presented with practical implications for its cost‐effective operation. 相似文献
478.
为了揭示煤粉尘爆炸过程中火焰传播特征,采用2种不同质量分数挥发分的煤粉在半封闭竖直燃烧管中进行实验。分别使用高速摄影装置和红外热成像装置记录火焰传播过程和空间的温度分布情况,并分析2种煤粉尘云的火焰传播速度和温度曲线。结果表明:在同等条件下,火焰在挥发分质量分数高的煤粉尘云中的传播速度和火焰温度要高于其在挥发分质量分数较低的煤粉尘云中的。煤粉尘云的体积质量和点火能量也影响着火焰的传播过程,随着煤粉尘云体积质量的增大,火焰的传播速度和火焰温度整体上呈现先增大后减小的趋势,在传播的后半段火焰速度出现震荡现象;随着点火能量的增大,火焰在煤粉尘云中的传播速度和最高温度也相应升高。通过大量的实验数据计算得到特定条件下火焰传播速度和温度的经验公式。 相似文献
479.
Muhammad Shakaib Iqbal Ahmed Rosli M. Yunus Ani Idris 《Journal of Macromolecular Science: Physics》2013,52(10):2049-2063
Formic acid (FA) solutions prepared with various concentrations of polyamide 66 (PA 66) and monosodium glutamate (MSG) were evaluated in terms of properties, such as density, viscosity, and cloud point. The influence on density was insignificant, whereas the viscosity was strongly affected by the amount of PA 66 and MSG additive. The solutions were further evaluated by casting them in a flat film form and determining the demixing time in a humid atmosphere. The considered cases at lower polymer concentrations at various MSG amounts, indicated that the demixing time increased with increase in polymer concentration. The time for demixing, however, decreased for a given higher amount of polymer when the amount of additive was increased in the dope solution. Membranes were prepared at various coagulant bath temperatures. The tensile strength and degree of adsorption (DOA) of these membranes were found. The tensile strength was higher when the membranes were prepared at higher temperature. The DOA, on the other hand, was higher for the membranes formed at lower temperature. 相似文献
480.