A survey on fall detection: Principles and approaches

Pattern recognition

"Graefe's Archive" is a distinguished international journal that presents original clinical reports and clinically relevant experimental studies. Founded in 1854 by Albrecht von Graefe to serve as a source of useful clinical information and a stimulus for discussion, the journal has published articles by leading ophthalmologists and vision research scientists for more than a century. With peer review by an international Editorial Board and prompt English-language publication, "Graefe's Archive" provides rapid dissemination of clinical and clinically related experimental information.

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Injuries that are caused by falls have been regarded as one of the major health threats to the independent living for the elderly. Conventional fall detection systems have various limitations. In this work, we first look for the correlations between different radio signal variations and activities by analyzing radio propagation model. Based on our observation, we propose WiFall, a truly unobtrusive fall detection system. WiFall employs physical layer Channel State Information (CSI) as the indicator of activities. It can detect fall of the human without hardware modification, extra environmental setup, or any wearable device. We implement WiFall on desktops equipped with commodity 802.11n NIC, and evaluate the performance in three typical indoor scenarios with several layouts of transmitter-receiver (Tx-Rx) links. In our area of interest, WiFall can achieve fall detection for a single person with high accuracy. As demonstrated by the experimental results, WiFall yields 90 percent detection precision with a false alarm rate of 15 percent on average using a one-class SVM classifier in all testing scenarios. It can also achieve average 94 percent fall detection precisions with 13 percent false alarm using Random Forest algorithm.

WiFall: Device-Free Fall Detection by Wireless Networks

Traditional and recent approaches in background modeling for foreground detection: An overview

The gradual accumulation of noisy evidence for or against options is the main step in the perceptual decision-making process. Using brain-wide electrophysiological recording in mice (Steinmetz et al., 2019), we examined neural correlates of evidence accumulation across multiple brain areas. We demonstrated that the neurons across the brain exhibited ramping-like firing rate activity that was modulated by the strength of evidence. These neurons had distinct properties in their intrinsic timescale, which were organized hierarchically across the brain. Our findings support the existence of evidence accumulation over multiple timescales. Furthermore, evaluating the underlying neural mechanism of evidence accumulation for the drift-diffusion-like neurons revealed different accumulation mechanisms (i.e. single and race) both within and across the brain areas. The results support the hypothesis that evidence accumulation is happening through multiple integration mechanisms in the brain. Significance Statement In this paper we characterized the perceptual decision-making process across the mouse brain, using brain-wide electrophysiological recordings. This paper provides a comprehensive analysis characterizing different aspects of the evidence accumulation process, including the distribution of accumulator-like neurons, the timescale of information integration, and the underlying neural mechanism of the evidence accumulation process.

/pdf/distributed-coding-of-evidence-accumulation-across-the-mouse-m7pl5yq4.pdf

Distributed coding of evidence accumulation across the mouse brain using microcircuits with a diversity of timescales

In this paper we present a novel method based on path normalization for classification in the traffic surveillance videos.  Extracting the low level feature vectors in various sizes and recording all spatial-temporal information without fixed sampling rate are the main reason in this normalization. The normalized feature vectors are used for unsupervised learning and since most people of society have legal traffic behaviors system can extract the necessary knowledge automatically to detect illegal behavior. In the proposed structure, decision making for these behaviors is based on spatial-temporal features. The experimental results show high accuracy in trajectories classification using path normalization.

/pdf/path-normalization-for-traffic-surveillance-video-retrieval-1da2m9pcd4.pdf

Path Normalization for Traffic Surveillance Video Retrieval

This paper study and analyzes of effective parameters on camera pose estimation process for virtual studio. The camera pose estimation process, the process of estimating camera extrinsic parameters, is based on closedform geometrical approaches which is used the benefic of simple corners detection of 3D cubic-like virtual studio’s landmarks. Our studies include all landmarks characteristic parameters like landmark’s lengths, landmark’s corners angles and its installation position errors; and some camera parameters like lens’ focal length and CCD resolution. We study and analyze all these parameters efficiency on camera extrinsic parameters including camera rotation and position matrixes through computer simulation. We found that the camera transaction matrix is infected more than other camera extrinsic parameters by the noise of effective pose estimation parameters.

/pdf/the-study-and-analysis-of-effective-parameters-on-camera-1c1bzl8gyb.pdf

The Study and Analysis of Effective Parameters on Camera Pose Estimation Process for Virtual Studio

In this article, the role of nano-size calcium carbonate in penetration resistance of mediumdensity polyethylene (PE) was investigated through experiments. In order to study the penetration resistance of PE and its nanocomposites, perforation test was carried out. The results of tests showed that penetration resistance depends strongly on calcium carbonate amount. As a matter of fact, addition of CaCO3 to PE increases resistance against penetration as CaCO3 amount reaches to 5 percent of weight. Stereomicroscope was used to evaluate the damage and plastic zone around the perforated area in all the samples including neat polyethylene and its nanocomposites. The plastic zone was measured using an image analysis as an effective technique. The results of image analysis techniques proved that the addition of calcium carbonate to PE makes a damaged zone around the perforated area. The results of microscopic evaluations showed that the area of plastic zone rises as the amount of calcium carbonate increases up to 7.5 percent of weight. By increasing the amount of CaCO3, resistance against penetration decreases more and some micro cracks appear around the perforated area. For further clarification of the fracture mechanism of MDPE nanocomposites, scanning electron microscopy was employed. Fracture surface images showed that when calcium carbonate is higher than 5 percent of weight, agglomeration of nanoparticles occurs, resulting in lower resistance against penetration to the samples.

Effect of nano-size calcium carbonate on perforation resistance of medium- density polyethylene

Most existing systems for calibrating multi-projector display suffered from several important limitations such as dependence on point of view, restriction on the display surface and moreover the number of projectors and using obtrusive markers. In this paper, a new method for view-independent calibration for multi-projector displays is presented. Given that the calibration problem of a multi-projector display is an optimization problem, we compute the calibration parameters by writing the appropriate energy functions for the geometric calibration phase. In this method, the camera and projector are introduced as a pair. In the first step, calibration of the pair of camera and projector was carried out. After that, the calibration problem of the system decreases to estimation of the number of camera positions relative to each other. In this method, there is no particular shape for the screen. In addition, due to the 3D shape of the screen, this method is view independent and eventually the image can be wallpapered on the screen. According to the tests carried out to evaluate the system, the accuracy of the proposed system is sub-pixel, and as a result, no misalignment is observed by the human eye in the overlapping area of projectors.

/pdf/scalable-and-view-independent-calibration-of-multi-projector-24cun31p1e.pdf

Hamid Reza Pourreza

Papers

Distributed coding of evidence accumulation across the mouse brain using microcircuits with a diversity of timescales

Path Normalization for Traffic Surveillance Video Retrieval

The Study and Analysis of Effective Parameters on Camera Pose Estimation Process for Virtual Studio

Effect of nano-size calcium carbonate on perforation resistance of medium- density polyethylene

Scalable and view-independent calibration of multi-projector display for arbitrary uneven surfaces