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基于RSSI的测距差分修正定位算法   总被引:15,自引:4,他引:11  
为了抑制RSSI误差对无线传感器节点自身定位精度的影响,以三边定位算法为基础,定义了个体差异差分系数、距离差分系数和距离差分定位方程,把离目标节点最近的信标节点作为参考节点对基于RSSI的测距进行差分修正,并将差分法和质心法相结合提出了一种测距差分修正定位算法。该定位算法无需增加额外硬件开销,容易实现,定位误差可小于2.5m,适合于处理能力和能量有限的无线传感器网络节点。  相似文献
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基于局部对称性特征的快速车标定位   总被引:1,自引:0,他引:1       下载免费PDF全文
根据车标区域及车体的对称性特征,提出了一种快速的车标定位方法。先通过垂直间隔差分和水平最大局部投影定位出车牌和车灯水平区域后,利用车牌、车灯和车标之间的几何位置和大小约束关系粗定位出车标区域,然后根据局部对称性和差分水平投影对粗定位区域进行二次定位,得到较精确的车标矩形区域。实验结果表明,平均定位准确率为94%,平均定位时间为21ms。  相似文献
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We are concerned with the detection of edges—the location and amplitudes of jump discontinuities of piecewise smooth data realized in terms of its discrete grid values. We discuss the interplay between two approaches. One approach, realized in the physical space, is based on local differences and is typically limited to low-order of accuracy. An alternative approach developed in our previous work [Gelb and Tadmor, Appl. Comp. Harmonic Anal., 7, 101–135 (1999)] and realized in the dual Fourier space, is based on concentration factors; with a proper choice of concentration factors one can achieve higher-orders—in fact in [Gelb and Tadmor, SIAM J. Numer. Anal., 38, 1389–1408 (2001)] we constructed exponentially accurate edge detectors. Since the stencil of these highly-accurate detectors is global, an outside threshold parameter is required to avoid oscillations in the immediate neighborhood of discontinuities. In this paper we introduce an adaptive edge detection procedure based on a cross-breading between the local and global detectors. This is achieved by using the minmod limiter to suppress spurious oscillations near discontinuities while retaining high-order accuracy away from the jumps. The resulting method provides a family of robust, parameter-free edge-detectors for piecewise smooth data. We conclude with a series of one- and two-dimensional simulations.To David Gottlieb, on his 60th birthday, with friendship and appreciation.  相似文献
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For branching-time temporal logic based on an Ockhamist semantics, we explore a temporal language extended with two additional syntactic tools. For reference to the set of all possible futures at a moment of time we use syntactically designated restricted variables called fan-names. For reference to all possible futures alternative to the actual one we use a modification of a difference modality, localized to the set of all possible futures at the actual moment of time.We construct an axiomatic system for this extended branching-time logic and prove its soundness and completeness with respect to bundle tree semantics. Finally, we show how our axiomatic system can be extended with a variety of important additional operators, such as Since and Until, a global difference operator, operators for undivided and divided histories, reference pointers, etc.  相似文献
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Despite the promised benefits of Enterprise Resource Planning (ERP) systems, more than two thirds of ERP system projects result in failure. In this study, we investigate some plausible reasons for their failure from the user’s perspective. Particularly, we propose the socio-technical factors that affect ERP system use. This study has two research objectives. First, it introduces and tests a theoretical model that views ERP systems as both an organizational change driver and a sophisticated information system to explain the phenomenon of ERP system use. For this purpose, the proposed model includes attitude toward change and computer self-efficacy; this may affect ERP system use behavior through perceived usefulness for the systems. Second, this paper attempts to shed some light on how the localization differences of ERP systems may affect users’ intention to use the ERP systems. The results based on survey data using subjects from two different ERP systems support the proposed research model. It identifies the moderating effect of the localization differences. Theoretical and practical implications of the study are discussed along with its limitations.  相似文献
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目的 为准确描述图像的显著信息,提出一种结合整体一致性和局部差异性的显著性检测方法,并将显著性特征融入到目标分割中。方法 首先,利用频率调谐法(IG)对目标整体特征的一致性进行显著性检测。然后,引入NIF算法检测显著目标的局部差异性。最后结合两种算法形成最终的显著性检测方法,并应用于图像目标分割。结果 在公认的Weizmann数据集上验证本文方法显示目标的绝对效率并与其他算法对比,实验结果表明本文方法在精确率,召回率,F1-measure(分别为0.445 6,0.751 2,0.576 4)等方面优于当前流行的算法。并且在融合显著性的图像目标分割中,取得满意的实验结果。结论 提出一种新的显著性检测算法,综合体现目标的整体和局部特征,并在公开数据集上取得较高的统计评价。实验结果表明,该算法能够对自然图像进行较准确的显著性检测,并成功地应用于自然图像的目标分割。  相似文献
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针对在无线传感器网络定位中,由于全向天线信号受环境影响而造成定位误差较大的问题,提出了一种改进的基于定向天线的移动无线传感器网络定位算法(DADLP),使用一个带有定向天线的移动锚节点广播位置信息,未知节点接收到信号后,将接收功率平均分为若干等级,缩小定位估计区域.仿真结果表明DADLP算法相对于Ssu、BLI、GGDI和RROI移动锚节点算法提高了定位精度,并且在非规则环境下有更低的平均定位误差.  相似文献
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