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21.
在浅海近似绝热环境中,利用虚拟接收方法对声源测距的目标定位方法相比于传统的匹配场定位方法可以避免对环境参数和声场模型的依赖,同时省去生成拷贝场时的大量计算·利用虚拟接收方法对声源测距主要是通过估计虚拟声场干涉条纹的斜率进行定位,而非完整阵列接收相当于引入了干扰项,破坏了虚拟声场干涉结构。引入了一种基于图像Hessian矩阵特征值分析的多尺度线性滤波器,通过数值模拟和实验数据处理,结果表明,该滤波器可以有效地增强干涉结构、检测和提取干涉图案中的条纹信息,提高非完整阵列接收条件下的虚拟接收目标定位技术的测距性能。 相似文献
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建筑物通常留有开口以便人员物料的进出及室内的自然通风采光,但这些开口也是噪声传播的途径。传统被动噪声控制方法需要将开口封闭,且对低频噪声的控制效果不好,故引入有源噪声控制技术降低室内声源通过开口的声辐射。基于惠更斯原理,均布开口的次级源和误差传声器构成的平面型虚拟声屏障可以实现对开口声辐射的有效控制,数值仿真和实验已证明其有效性。将次级源安装在开口边界更有利于保留开口的功能且方便实际安装,但这样的单层边界虚拟声屏障降噪效果存在上限,仅能在低频段实现全局控制。和单层边界次级源相比,双层边界次级源可显著提高降噪量和有效降噪频率上限。该文回顾了开口声辐射有源控制的相关工作,并讨论了未来可能的研究方向。 相似文献
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A semi-analytical solution is presented for the virtual mass coefficient of an oblate-ellipsoidal bubble rising in liquid. The solution was found to be a function of Weber number. The present solution compared well with the numerical solution of the lattice Boltzmann method and the analytical solutions of other investigators. 相似文献
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A new branch-and-bound algorithm is presented to solve the two-sided assembly line balancing problem of type 1 (TALB-1). First, a pair of two directly facing station is defined as a position, and then the two-sided assembly line (TAL) is relaxed to a one-sided assembly line (OAL). Some new lower bound on positions are computed, and dominance rules and reduction rules for the one-sided assembly line balancing problem of type 1 (OALB-1) are extended and incorporated into a station-oriented assignment procedure for the TALB-1 problem. Finally, the tests are carried out on a well-known benchmark set of problem instances, and experimental results demonstrate that the proposed procedure is efficient. 相似文献
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Comparison of compounds similarity is one of the main strategies of virtual screening protocols. Both similarity and dissimilarity concepts are of great importance during the search for new active compounds. Similarity is important due to the assumption that underlies the process of searching for new drug candidates: structurally similar compounds should induce similar biological response. On the other hand, we are also interested in dissimilarity, as we usually aim to find structurally novel ligands. In the study, we compared several approaches of evaluating compound similarity. Various representations and metrics were applied and we indicated the rate of variation of the results that can occur when shifting from one strategy to another. We compared both general similarity of datasets using different approaches, as well as examined the changes in the set of nearest neighbors when changing one compound representation into another, and the influence of representation/metric settings on the clustering outcome. We hope that the study will be of great help during the preparation of virtual screening experiments, stressing the need for careful selection of the way, the compound similarity is assessed. The differences in the results that can be obtained via the application of particular strategy can significantly influence the outcome of comparison studies; therefore, its settings should be carefully selected beforerunning the comparison. 相似文献