检索结果-内蒙古大学图书馆

Investigation and Modeling of Large Barkhausen Jumps Dynamics in Low-Power Fluxgate Magnetometers

IEEE SENSORS JOURNAL 2019年第6期19卷 2105-2112页

作者： Weiss, Eyal Alimi, Roger Ivry, Amir Fisher, Elad Soreq NRC Technol Div IL-81800 Yavne Israel

Large Barkhausen jumps occur in low-power fluxgates output and seriously affect the signal fidelity and therefore the magnetometer functionality. In this paper, we investigate the occurrence of DC jumps in two types of fluxgates, parallel and orthogonal. We present a new model for the jumps phenomenon. This model is based on the reversal dynamics of magnetic domains in the core metallurgical super-structures. We expand the model to explain how and why the jumps subside in time. We show that although the jumps rate decays exponentially in time, the process never completely stops. The understanding of DC jumps dynamics may be utilized in research and development of low-power magnetic sensors. It may he used to characterize and standardize the quality of magnetic sensors cores and used to screen faulty cores that exhibit exceptionally high jump rate that may affect signal fidelity. Mitigating the jumps in both parallel and orthogonal low-power fluxgates is crucial for low-noise magnetic measurement systems.

关键词： Magnetometers low power Barkhausen noise magnetic noise DC jumps detection algorithm signal fidelity

来源：评论

学校读者我要写书评

暂无评论

Wheel flat detectability for Y25 railway freight wagon using vehicle component acceleration signals

引用

VEHICLE SYSTEM DYNAMICS 2020年第12期58卷 1893-1913页

作者： Bernal, Esteban Spiryagin, Maksym Cole, Colin Cent Queensland Univ Ctr Railway Engn Rockhampton Qld Australia

A wheel flat is a common fault in railway vehicles that may develop after incorrect brake application, or localised wheel-rail adhesion reduction. Operators detect wheel flats using wayside systems that are not capable of delivering real-time alarms. A wheel flat defect was modelled and introduced to a railway wagon multibody dynamic simulation to study the vehicle dynamic behaviour triggered by such wheel tread defect. Bogie-based and car body-based wheel flat detection was evaluated to determine eventual hardware robustness and signal processing requirements for on-board wheel flat detection devices. Various vehicle operating conditionds and wheel flat defects were simulated to analyse the wheel flat impact propagation throughout the railway vehicle bodies. Wheel defect detectability was assessed using detectability indicators (DIs) based on envelope power spectrum analysis, crest factor and RMS. It was found that bogie and car body-based wheel flat detectability is highly dependent on the track characteristics. The wheel flat signature was reduced in the wheelset-bogie and bogie-car body interfaces, indicating that advanced signal processing techniques are required for bogie-based and car body-based wheel flat detection systems. The DIs showed clear differences between healthy and faulty wheelset and bogie frame acceleration signals, which is promising for eventual on-board wheel flat detection systems.

关键词： Wheel flat freight wagon fault simulation detection algorithm

来源：评论

学校读者我要写书评

暂无评论

Trainable Projected Gradient Detector for Massive Overloaded MIMO Channels: Data-Driven Tuning Approach

引用

IEEE ACCESS 2019年 7卷 93326-93338页

作者： Takabe, Satoshi Imanishi, Masayuki Wadayama, Tadashi Hayakawa, Ryo Hayashi, Kazunori Nagoya Inst Technol Nagoya Aichi 4668555 Japan RIKEN Ctr Adv Intelligence Project Tokyo 1030027 Japan Kyoto Univ Grad Sch Informat Kyoto 6068501 Japan Osaka City Univ Grad Sch Engn Osaka 5588585 Japan

This paper presents a deep learning-aided iterative detection algorithm for massive overloaded multiple-input multiple-output (MIMO) systems where the number of transmit antennas n is larger than that of receive antennas m. Since the proposed algorithm is based on the projected gradient descent method with trainable parameters, it is named the trainable projected gradient-detector (TPG-detector). The trainable internal parameters, such as the step-size parameter, can be optimized with standard deep learning techniques, i.e., the back propagation and stochastic gradient descent algorithms. This approach is referred to as data-driven tuning and ensures fast convergence during parameter estimation in the proposed scheme. The TPG-detector mainly consists of matrix-vector product operations whose computational cost is proportional to mn for each iteration. In addition, the number of trainable parameters in the TPG-detector is independent of the number of antennas. These features of the TPG-detector result in a fast and stable training process and reasonable scalability for large systems. The numerical simulations show that the proposed detector achieves a comparable detection performance to those of the existing algorithms for the massively overloaded MIMO channels, e.g., the state-of-the-art IW-SOAV detector, with a lower computation cost.

关键词： Massive MIMO overloaded MIMO detection algorithm deep learning

来源：评论

学校读者我要写书评

暂无评论

RECOGNITION OF VENTRICULAR-FIBRILLATION USING NEURAL NETWORKS

引用

MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING 1994年第2期32卷 217-220页

作者： CLAYTON, RH MURRAY, A CAMPBELL, RWF FREEMAN RD HOSP DEPT ACAD CARDIOLNEWCASTLE TYNE NE7 7DNTYNE & WEARENGLAND

This study has focused on one aspect of arrhythmia monitoring which poses a difficult problem for automatic analysis. The results show that neutral network are capable of recognising patterns in the spectrum of the ECG during VF and can distinguish genuine VF from VF-like artifact. The best performance was obtained a network which required some preprocessing of the signal spectrum as well as the additional training. This neural network had a better sensitivity for VF detection than conventional techniques assessed previously using the same data set.

关键词： detection algorithm ECG ANALYSIS NEURAL NETWORKS VENTRICULAR FIBRILLATION

来源：评论

学校读者我要写书评

暂无评论

Keratoconus screening using wavefront parameters based on corneal topography height data

引用

KLINISCHE MONATSBLATTER FUR AUGENHEILKUNDE 1999年第4期214卷 217-223页

作者： Langenbucher, A Gusek-Schneider, GC Kus, MM Huber, D Seitz, B Univ Erlangen Nurnberg Augenklin Poliklin D-91054 Erlangen Germany

Background The image-forming properties of a keratoconus eye are degraded even in the early stage of this disease. The purpose of this study was to develop keratoconus detection scheme based on topography height data independent of the currently used system which avoids the disadvantages of detection algorithms currently used in clinical practice. Patients and methods Eighty-eight patients with keratoconus (46 with mild and 42 with severe clinical signs) and a control group of 40 normal subjects were included in this study. A decomposition of corneal topography height data into orthogonal Zernike polynomials was performed using the commercially available corneal topographer TMS-1. Expansion coefficients of the different groups were compared to evaluate significant differences. Elevated terms were used to detect the disease. The statistical significance of this detection scheme was compared to those given by the keratoconus detection software of the TMS-1. From the elevated Zernike terms a neural network was constructed and optimized for dividing keratoconus patients and normal controls. Results Some low-order Zernike coefficients with a radial order n < 8 were found to be elevated in patients with keratoconus and were used to define a new detection algorithm. This index performed at least as well (sensitivity in mild/ severe keratoconus 93,4%/100% with a specifity of 100%) as keratoconus detection schemes based on the Klyce-Maeda and the Rabinowitz-Klyce indices as well as the I-S value and the Surface Asymmetry Index SAI in our study population. Conclusions Zernike decomposition of corneal topography height data allows a definition of an exact and robust algorithm for detection of keratoconus. It avoids the drawbacks of refractive power based definitions and is independent on the individual topographer design.

关键词： keratoconus corneal topography wavefront parameters height data detection algorithm

来源：评论

学校读者我要写书评

暂无评论

Steady state algorithm for leak diagnosis in water pipeline systems

引用

IFAC-PapersOnLine 2018年第13期51卷 402-407页

作者： Lizarraga-Raygoza, A. Delgado-Aguiñaga, J.A. Begovich, O. CINVESTAV Guadalajara Av. del Bosque 1145 colonia el Bajío ZapopanJalisco45019 Mexico Universidad del Valle de México CIIDETEC Campus Guadalajara Sur Manuel Gómez Morín 8100 San Pedro TlaquepaqueJalisco45601 Mexico

This work proposes an algorithm for leak diagnosis in pipelines based on a steady-state analysis. The motivation of this proposition arises from the fact that often leaks appear in specific locations in water pipeline systems, namely in between two consecutive pipeline stretches (junctions), according with experience of the staff of a real water distribution network. By dismissing other kind of leaks (as leaks in oil pipelines) for which other considerations must be taken into account, this work is focused to the most normal events of leaks in water pipeline systems, and here, the leak diagnosis problem is reduced to identify the junction where the leak occurs. To do that, a steady-state expression is obtained from the classical Water Hammer equations and it is used to compute a drop pressure head between the pipeline ends for each junction. Then this estimation is compared with the one computed by using the pressure head measurements. Finally for each case a residual can be generated and the junction position that produces a residual closer to zero is finally identified as the leak location. The main advantage of this proposition is that the uncertainties in the leak location are not longer important, i. e., the leak location can be given with an exact position as long as the configuration of the pipeline (possibly located underground) is well known. For sake of illustration, some examples are provided via simulations. © 2018

关键词： Leakage (fluid) Failure analysis Fault detection Location Pipelines Piping systems Water distribution systems Water pipelines Algebraic approaches detection algorithm Diagnostic tests Steady state Steady state analysis Steady state expression Water distribution networks Water hammer equations

来源：评论

学校读者我要写书评

暂无评论

Potential of Acoustic Emission in Unsupervised Monitoring of Gas-Fuelled Engines

引用

IFAC-PapersOnLine 2016年第23期49卷 329-334页

作者： Bondarenko, Oleksiy Fukuda, Tetsugo National Institute of Maritime Port and Aviation Technology Japan

The aim of this paper is to scrutinise closely information that contains in the acoustic emission of a gas-fuelled engine and to define the potential of knock condition detection. The recently introduced technique of nonstationary system identification is investigated. At first, it utilises the wavelet transform to reveal time-frequency energy density of data. Then the modified version of singular value decomposition is applied to extract dominant frequency components from the data buried in background noise. The efficacy of knock feature extraction is investigated using three sources of data: in-cylinder pressure, engine structure vibration and engine noise sensed by a microphone. © 2016

关键词： Acoustic emission testing Accident prevention Acoustic noise Engine cylinders Singular value decomposition Stratified charge engines Wavelet transforms Condition detection detection algorithm Dominant frequency Engine management Filtering technique Gas fuelled engines In cylinder pressures Non stationary system identifications

来源：评论

学校读者我要写书评

暂无评论

Spatial Filtration with Allowance for Changes in the Observed Image of the Object during Its Microscanning

引用

OPTOELECTRONICS INSTRUMENTATION AND DATA PROCESSING 2018年第5期54卷 457-462页

作者： Shakenov, A. K. Budeev, D. E. Russian Acad Sci Inst Automat & Electrometry Siberian Branch Pr Akad Koptyuga 1 Novosibirsk 630090 Russia Siberian State Univ Telecommun & Informat Ul Kirova 86 Novosibirsk 630102 Russia

A filtration algorithm is proposed for detecting objects in images obtained by means of microscanning. An algorithm for calculating the filter for an object with a known shape is presented. The influence of changes in the object shape induced by a subpixel displacement of the object with respect to the center of the photosensitive cell on the filtration results is studied. An approach to choosing the filter shape with allowance for object shape changes is tested. Results of numerical simulations are reported.

关键词： small-size object detection algorithm subpixel displacement microscanning image filtration algorithm

来源：评论

学校读者我要写书评

暂无评论

COMPARISON OF 4 TECHNIQUES FOR RECOGNITION OF VENTRICULAR-FIBRILLATION FROM THE SURFACE ECG

引用

MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING 1993年第2期31卷 111-117页

作者： CLAYTON, RH MURRAY, A CAMPBELL, RWF FREEMAN RD HOSP DEPT ACAD CARDIOL NEWCASTLE UPON TYNE NE7 7DN TYNE & WEAR ENGLAND

Four ventricular fibrillation (VF) detection techniques were assessed using recordings of VF to evaluate sensitivity and VF-like recordings to evaluate specificity. The recordings were obtained from Coronary Care Unit patients. The techniques were: threshold crossing intervals (TCI);peaks in the autocorrelation function (ACF);signal content outside the mean frequency (VF-filter);and signal spectrum shape (spectrum). Using 70 extracts, each 4 s long, from VF recordings, the VF filter achieved a sensitivity of 77 per cent, the ACF, TCI and spectrum algorithms had sensitivities of 67, 53 and 46 per cent, respectively. Susceptibility to false alarms was assessed using 40 extracts from VF-like recordings. The TCI algorithm was the most specific (93 per cent), while the spectrum, VF filter and ACF algorithms had specificities of 72, 55 and 38 per cent, respectively. The TCI algorithm achieved overall sensitivity of 93 per cent and specificity of 60 per cent. The spectrum, VF filter and ACF algorithms had overall sensitivities of 80, 93 and 87 per cent, and overall specificities of 60, 20 and 0 per cent, respectively.

关键词： DEFIBRILLATION detection algorithm ECG MONITORING VENTRICULAR FIBRILLATION

来源：评论

学校读者我要写书评

暂无评论

Diagnostic performance of a dual-chamber cardioverter defibrillator programmed with nominal settings: A European prospective study

引用

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY 2002年第1期13卷 25-32页

作者： Sadoul, N Jung, W Jordaens, L Leenhardt, A Santini, M Wolpert, C Aliot, E CHU Nancy Brabois Serv Cardiol F-54511 Vandoeuvre Les Nancy France Univ Bonn Klin Bonn Germany Univ Ziekenhuis Ghent Belgium Hop Univ Lariboisiere Paris France Osped S Filippo Neri Rome Italy

Introduction: Despite technologic developments, accurate discrimination of ventricular tachyarrhythmia from rapid rhythms of nonventricular origin remains a challenge. We sought to examine the sensitivity and specificity of a dual-chamber arrhythmia detection algorithm, the PARAD algorithm, incorporated in a dual-chamber implantable cardioverter defibrillator, the Defender (ELA Medical). Methods and Results : All detailed tachycardia episodes (i.e., with stored atrial and ventricular channel markers and electrograms) retrieved from the Holter memory of the device were analyzed from 95 patients (86 men and 9 women;age 62 +/- 12 years) implanted with the Defender with the algorithm programmed at nominal settings. Over a follow-up of 15 +/- 8 months, 559 detailed sustained tachycardia episodes detected in the tachycardia zone were gathered in 62 patients. Of the 300 ventricular tachycardia (VT) episodes, 298 were appropriately classified as VT by the algorithm. Of the 259 supraventricular tachycardia (SVT) episodes, 231 were appropriately classified as SVT. In 8 patients, 28 episodes of SVT were misclassified as VT: 25 atrial fibrillation episodes (6 patients), 2 sinus tachycardia (1 patient), and 1 atrial tachycardia. Calculated sensitivity and specificity were 99.3% and 89.2% on a per episode basis and 99.8% (95% confidence interval: 97.8 to 100) and 91.6% (95% confidence interval: 86.0 to 97.3) on a per patient basis, respectively. Conclusion: In this selected population of patients, the PARAD algorithm was safe and reliable for detection of a wide spectrum of tachyarrhythmias. Its specificity was high, particularly with respect to sinus tachycardia detection, but it must be improved with respect to detection of atrial fibrillation.

关键词： implantable cardioverter defibrillator dual chamber detection algorithm

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：