共查询到19条相似文献,搜索用时 156 毫秒
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随着无线传感器网络的应用与发展,WSN作为一种全新的信息获取和处理技术已得到广泛应用。如何对传感器网络节点进行快速、精确的定位,已成为WSN系统急需解决的问题。为此,提出了一种基于RSSI距离比的MDS定位算法。该算法巧用RSSI距离比,结合Euclidean测距技术计算节点间距离矩阵,运用MDS算法建立相应的全局坐标系统。根据已知锚节点物理位置,通过坐标变换(旋转与平移)最终确定未知节点的物理位置。实验结果表明:该方法能有效地提高定位的精度,对开发高精度定位系统具有重要的参考价值。 相似文献
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目的:寻找更有效的HRV信息处理的方法和指标。方法:对HRV信号进行多尺度小波变换,用DWT算法进行均方差估计;将小波分析方法和传统的频谱测量方法进行分析和比较。结果:DWT均方差测量与PSD测量结果在原理上是等价的,但小波均方差估计D(m)在低频率范围内具有更好的频率分辨能力。结论:在处理HRV信号时小波分析方法优于传统的频谱测量方法。 相似文献
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重症监护病人心电导联信号质量评估 总被引:3,自引:0,他引:3
目的:研究基于重症监护病人心电导联的信号质量评估算法。方法:通过分析信号的波形特征、统计特性和相互关系导出反映信号质量高低的信号质量指数(Signal Quality Index, SQI),并基于SQI进行病人的心率估计,应用美国麻省理工学院多参数智能重症监护数据库Ⅱ中437例病人的6000多小时高质量数据和添加的各类心电干扰的数据进行算法评价。结果:SQI随信噪比的降低而减小;SQI与心电搏动检测灵敏度和正检测率呈高度正相关关系;基于信号质量评估算法,在严重干扰存在时仍能提供精确的心率估计。结论:信号质量评估算法可对心电信号质量给出客观的评价。 相似文献
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[目的 ]对心电图数据进行预处理和特征提取。 [方法 ]对心电 (ECG)信号的检测 ,最关键的是对QRS波群的检出。本研究利用小波在时、频两域具有表征信号局部特性的能力 ,适当选择基本小波 ,应用Mallat算法对心电图信号进行多尺度分解从而检测出QRS波。 [结果 ]在Mallat算法实现时 ,选用适当的基本小波 ,清晰的检测出了QRS波群。 [结论 ]小波变换原理检测ECG信号中QRS波群具有很好的效果 ,而且选用不同的基本小波 ,可以检测出不同频率成份的波段 ,这样也同样达到了去除噪声的目的 相似文献
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传统的DFT-LS算法在最小二乘(LS)估计的基础上对循环前缀以外的信道冲击响应置零,在性能优于最小二乘(LS)的同时,降低了估计算法的计算复杂度。理想的最小均方差(MMSE)算法与其相比,计算复杂度大,但是性能优于DFT-LS。本文在传统DFT-MMSE估计算法基础上提出了一种新的方法,针对传统DFT-MMSE算法只对循环前缀以外的信道冲击响应做置零处理的问题,对循环前缀以内的信道冲击响应设定阈值门限,有效滤除部分循环前缀以内的噪声。理论分析与仿真结果表明,本文方法的性能优于传统的DFT-MMSE估计算法,劣于理想情况下的MMSE估计算法;计算复杂度低于传统的DFT-MMSE估计算法和理想情况下的MMSE估计算法。 相似文献
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GPRS移动式心电监护系统的QRS波实时检测算法 总被引:4,自引:0,他引:4
目的探讨GPRS移动式心电监护系统ECG信号QRS波的实时检测算法.方法采用四点平均对CM5导联的ECG信号进行滤波,再对ECG信号的一、二阶差分值进行平滑处理,利用ECG信号的二阶差分值极小值和一阶差分过零点在较短的时间窗内实现QRS波精确定位,并设计了具有自学习和自适应功能的信号检测门限.结果算法能抑止多种噪声对ECG信号的影响,将搜索的时间窗宽度缩小到0.02 s以下,且算法只具有多项式的复杂度;经过临床测试,动态ECG信号进QRS波检测准确率可达99.8%以上.结论该算法适合于移动心电监护系统QRS波的实时检测和分析. 相似文献
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在目前临床脑电医生常用的脑癫痫信号识别方法基础上,提出了一种利用计算机自动识别脑癫痫信号的方法及实现过程,该方法通过对脑电信号的形态特征的提取与在时空域进行综合分析的方法,模拟脑电专家的逻辑推理过程,将脑癫痫信号分为5类:尖波、棘波、尖慢波、棘慢波和多棘慢波来识别。经30例临床脑电信号检验,本系统检出率达90.38%,证明了系统的有效性。 相似文献
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Keiko Yamashita Shintaro Oyama Tomohiro Otani Satoshi Yamashita Taiki Furukawa Daisuke Kobayashi Kikue Sato Aki Sugano Chiaki Funada Kensaku Mori Naoki Ishiguro Yoshimune Shiratori 《J Am Med Inform Assoc》2021,28(3):477
PurposeLocation visualization is essential for locating people/objects, improving efficiency, and preventing accidents. In hospitals, Wi-Fi, Bluetooth low energy (BLE) Beacon, indoor messaging system, and similar methods have generally been used for tracking, with Wi-Fi and BLE being the most common. Recently, nurses are increasingly using mobile devices, such as smartphones and tablets, while shifting. The accuracy when using Wi-Fi or BLE may be affected by interference or multipath propagation. In this research, we evaluated the positioning accuracy of geomagnetic indoor positioning in hospitals.Materials and MethodsWe compared the position measurement accuracy of a geomagnetic method alone, Wi-Fi alone, BLE beacons alone, geomagnetic plus Wi-Fi, and geomagnetic plus BLE in a general inpatient ward, using a geomagnetic positioning algorithm by GiPStech. The existing Wi-Fi infrastructure was used, and 20 additional BLE beacons were installed. Our first experiment compared these methods’ accuracy for 8 test routes, while the second experiment verified a combined geomagnetic/BLE beacon method using 3 routes based on actual daily activities.ResultsThe experimental results demonstrated that the most accurate method was geomagnetic/BLE, followed by geomagnetic/Wi-Fi, and then geomagnetic alone.DiscussionThe geomagnetic method’s positioning accuracy varied widely, but combining it with BLE beacons reduced the average position error to approximately 1.2 m, and the positioning accuracy could be improved further. We believe this could effectively target humans (patients) where errors of up to 3 m can generally be tolerated.ConclusionIn conjunction with BLE beacons, geomagnetic positioning could be sufficiently effective for many in-hospital localization tasks. 相似文献
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In this paper, a more effective use of Doppler techniques is presented for the purpose of diagnosing atherosclerosis in its
early stages using the carotid artery Doppler signals. The power spectral density (PSD) graphics are obtained by applying
the short-time Fourier transform (STFT)-Welch and the Eigenvector MUSIC methods to the discrete wavelet transform (DWT) of
Doppler signals. The PSDs for the fourth approximation component (A4) of both methods estimated that the patients with atherosclerosis
in its early phase had lower maximum frequency components. On the other hand, the healthy subjects had higher maximum frequency
components. The area under the curve (AUC), which belongs to the receiver operating characteristic (ROC) curve for the frequency
level of the maximum PSDs of the A4 approximation obtained from the STFT modeling, is computed as 0.97. The AUC for the MUSIC
modeling is computed as 0.996. The AUC belonging to the ROC curve for the higher maximum frequency component is computed as
0.87. The AUC belonging to the ROC curve for the test parameter of the frequency level of the maximum PSDs derived from the
MUSIC modeling is determined to be 0.882. The results of this study clearly demonstrate that it is possible to distinguish
between the healthy people and the patients with atherosclerosis by using the frequency level of the maximum PSDs for the
A4 approximation. Furthermore, it is concluded that the power of Eigenvector-MUSIC method in terms of the resolution of the
high frequencies is better than that of the STFT methods. 相似文献
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针对传统方法不易收敛到真实Pareto前端和解的多样性较差的问题,提出了一种基于自适应网络和动态拥挤距离的多目标粒子群优化算法。该算法能在外部种群的数量超过种群规模时,将目标函数空间均匀地划分为间隔相同的网格,统计每个网格中粒子的数量进而估计粒子的密度,限制外部档案的规模;然后引入粒子的方差信息,设计了基于动态拥挤距离的算法,避免了一次性淘汰所有拥挤距离小的个体而使解的分布性变差的问题,提高了解的多样性。函数优化实验及该算法在成品油调和经济效益问题中的应用都验证了改进后的算法具有很好的效果。 相似文献
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利用小波支持向量回归,实现了遥感多光谱图像分辨率的增强。首先采用非下采样Contourlet变换对低分辨率的多光谱图像和高分辨率的全色图像进行多分辨率分解,再利用小波支持向量回归对分解系数进行学习和预测,获得分辨率初步提高的多光谱图像,最后再与传统的插值方法得到的结果进行融合来实现多光谱图像分辨率增强。实验结果表明:此方法借遥感全色图像的辅助获得丰富的高频细节信息,使得分辨率增强结果无论是最小均方误差还是峰值信噪比都要优于仅依靠原图像本身放大的传统方法以及其他的分辨率增强方法。 相似文献
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超宽带(UltraWideband,UWB)生物雷达广泛应用于生命体探测等领域,而人体生命体征信息的非接触检测是其需解决的最主问题。本文利用参数化双谱估计算法分析UWB生物雷达回波信号,以非高斯白噪声激励的AR(AutoRegression)参数模型对信号进行建模,并用带约束的三阶平均法对模型的参数进行估计。在此基础上,提出了一种新的基于UWB的人体目标非接触检测算法,并将该算法与现行的基于功率谱密度的检测算法进行对比、实验结果表明,有人位置点信号和无人位置点信号在双谱域表现出明显的差别特性,新算法能更好地实现人体目标的非接触检测。 相似文献
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