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排序方式: 共有690条查询结果,搜索用时 15 毫秒
91.
定位是车辆自主驾驶研究过程中的关键问题.从车辆的侧向动力学模型出发,研究并分析了其稳态响应结果,以此建立了车辆定位模型.由于定位模型具有非线性、多自由度、多变元的特点,在实际定位中很难应用.因此,在定位模型中采用了一种动态自适应网络即改进型的RBFNN,它能够动态调节网络的规模和参数,具有较强的逼近能力以及自学习能力;并利用Kalman滤波器对输入的前轮摆角以及车速信号进行滤波处理,减小误差,提高定位精度.实车实验中,定位方法能够得到较高的定位结果,东、北向位置误差均不超过1米.实验结果表明,是一种可行、有效的定位方法,可以在实车上使用. 相似文献
92.
93.
Donatas Trapenskas
rjan Johansson 《International Journal of Industrial Ergonomics》2001,27(6):405-410
One of the problems associated with listening to binaurally recorded sound events is localization confusions. The main objective of this investigation was to find out whether a short training session prior to listening to binaural recordings through headphones would facilitate correct spatial perception of the sound field. Focus was on the localization of the sound stimuli in median plane. Sound signals were recorded with an artificial head in three different conditions namely, anechoic, highly reverberant and moderately reverberant. Fourteen subjects participated in the listening tests. All subjects were required to localize all virtual sound stimuli under two different conditions. The first condition had a short training session binaurally recorded in the same environments as preceeding sound stimuli, and only sound stimuli recorded in the same environment were presented. The second condition did not have a training session, and sound stimuli recorded in different environments were presented. Results showed that a short training session prior to listening to binaurally recorded sounds through headphones was useful as it facilitated localization performance. The biggest effect was in reduced amount of sounds perceived inside the head. It was most pronounced for sound stimuli recorded in anechoic environment. 相似文献
94.
Pawe Kuakowski Javier Vales-Alonso Esteban Egea-Lpez Wiesaw Ludwin Joan García-Haro 《Computers & Electrical Engineering》2010,36(6):1181-1186
Among the large number of contributions concerning the localization techniques for wireless sensor networks (WSNs), there is still no simple, energy and cost efficient solution suitable in outdoor scenarios. In this paper, a technique based on antenna arrays and angle-of-arrival (AoA) measurements is carefully discussed. While the AoA algorithms are rarely considered for WSNs due to the large dimensions of directional antennas, some system configurations are investigated that can be easily incorporated in pocket-size wireless devices.A heuristic weighting function that enables decreasing the location errors is introduced. Also, the detailed performance analysis of the presented system is provided. The localization accuracy is validated through realistic Monte-Carlo simulations that take into account the specificity of propagation conditions in WSNs as well as the radio noise effects. Finally, trade-offs between the accuracy, localization time and the number of anchors in a network are addressed. 相似文献
95.
Hüseyin Akcan Vassil Kriakov Hervé Brönnimann Alex Delis 《Journal of Parallel and Distributed Computing》2010
A critical problem in mobile ad hoc wireless sensor networks is each node’s awareness of its position relative to the network. This problem is known as localization. In this paper, we introduce a variant of this problem, directional localization, where each node must be aware of both its position and orientation relative to its neighbors. Directional localization is relevant for applications that require uniform area coverage and coherent movement. Using global positioning systems for localization in large scale sensor networks may be impractical in enclosed spaces, and might not be cost effective. In addition, a set of pre-existing anchors with globally known positions may not always be available. In this context, we propose two distributed algorithms based on directional localization that facilitate the collaborative movement of nodes in a sensor network without the need for global positioning systems, seed nodes or a pre-existing infrastructure such as anchors with known positions. Our first algorithm, GPS-free Directed Localization (GDL) assumes the availability of a simple digital compass on each sensor node. We relax this requirement in our second algorithm termed GPS- and Compass-free Directed Localization (GCDL). Through experimentation, we demonstrate that our algorithms scale well for large numbers of nodes and provide convergent localization over time, despite errors introduced by motion actuators and distance measurements. In addition, we introduce mechanisms to preserve swarm formation during directed sensor network mobility. Our simulations confirm that, in a number of realistic scenarios, our algorithms provide for a mobile sensor network that preserves its formation over time, irrespective of speed and distance traveled. We also present our method to organize the sensor nodes in a polygonal geometric shape of our choice even in noisy environments, and investigate the possible uses of this approach in search-and-rescue type of missions. 相似文献
96.
无线传感器网络中一种精细距离控制定位算法 总被引:1,自引:0,他引:1
在Hop-terrain定位算法的基础上,提出了一个新的改进定位算法。新算法先利用由距离向量交换获得的普通节点与信标节点间的跳数距离进行传感器节点的初始位置估计;然后利用节点初始估计位置和节点直接邻居信息进行节点位置的迭代更新。在更新阶段,为了降低误差,引入了一种精细距离控制机制。该距离控制机制参考到高可信度权值邻居节点的距离约束关系,选择可能的最好节点位置作为最新迭代定位结果。仿真结果表明,与原算法相比,该算法能提高定位节点的比例,降低节点定位误差。 相似文献
97.
98.
秦静 《山东大学学报(工学版)》1994,(4)
讨论Clifford一半群S在其幂等元半格E上的局部化与S的最小群同余之间的关系.并给出Clifford-半群的半直积在其幂等元半格上的局部化. 相似文献
99.
100.
This paper presents the outcomes of a comprehensive experimental, metallurgical and finite element (FE) simulation study to characterize the development of adiabatic shear band (ASB) phenomenon in steel cold heading (CH) process. The main objective of this work is to investigate the complex interplay of different process and material parameters on the ASB development stages inside the cold headed parts.In this work, the drop weight compression test (DWCT) was selected to simulate the CH process impact loads on specimens machined from 1038 steel and 1018 steel. Series of DWCTs were performed under different impact loading conditions. The goal of these tests is to achieve different deformation levels and introduce ASBs at different stages.To reach a full understanding of this complex phenomenon, the FE simulation analysis was used to support the metallurgical examination of the DWCT specimens. The FE analysis provided important details about the changes of different material and process parameters at the critical zones inside the ASBs.This study confirmed that the ASB is mainly a thermo-mechanically controlled phenomenon. The ASBs develop in three stages: homogeneous plastic strain, inhomogeneous plastic strain, and strain localization. The ASB development stage depends mainly on the status of the competition between the work hardening and the thermal and geometrical softening mechanisms inside the bands. The domination of the softening mechanisms at advanced levels of deformation triggers a self-catalytic strain localization and material strength degradation process that leads to failure inside the band.In general, the metallurgical and finite element analysis investigation revealed that under impact loads, three ASBs can develop simultaneously inside the cold headed parts; lower, upper and central ASBs. As the deformation continues; the development of the lower and upper bands slows down and contributes in the rapid development of the adjacent central ASB. This study confirmed that the ASB has a canonical structure which leads to an ASB that can experience different development stages along the same band simultaneously.This study proved that the shape and the type of ASBs in cold headed parts depend highly on material's properties. The metallurgical and finite element analysis revealed that the higher the strength of the tested steel, the easier to form a narrow ASB that reaches the localization stage at low deformation levels. In contrast, ductile steels experience wider ASBs when subjected to the same deformation levels. These bands require higher levels of deformation to reach the localization stage in comparison to higher strength steels. 相似文献