Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Radar”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMed2005

Multiregion level-set partitioning of synthetic aperture radar images.

The purpose of this study is to investigate Synthetic Aperture Radar (SAR) image segmentation into a given but arbitrary number of gamma homogeneous regions via active contours and level sets. The segmentation of SAR images is a difficult problem due to the presence of speckle which can be modeled as strong, multiplicative noise. The proposed algorithm consists of evolving simple closed planar curves within an explicit correspondence between the interiors of curves and regions of segmentation to minimize a criterion containing a term of conformity of data to a speckle model of noise and a term of regularization. Results are shown on both synthetic and real images.

Algorithms↗
PubMed2006

Sequential monitoring of burials containing large pig cadavers using ground-penetrating radar.

Ground-penetrating radar (GPR) was used to monitor 12 pig burials in Florida, each of which contained a large pig cadaver. Six of the cadavers were buried in sand at a depth of 0.50-0.60 m, and the other six were buried at a depth of 1.00-1.10 m and were in contact with the upper surface of a clay horizon. Control excavations with no pig internment were also constructed as blank graves and monitored with GPR. The burials were monitored with GPR for durations of either 12-13 or 21-21.5 months when they were then excavated to correlate the decomposition state of the cadaver with the GPR imagery. Overall, cadavers in sand were easily detected for the duration of this study at 21.5 months, even when completely skeletonized. Conversely, in clay it became increasingly difficult to image the pig cadavers over the first year of burial, even when they still retained extensive soft tissue structures.

Animals↗
PubMed2003

Radar evidence for liquid surfaces on Titan.

Arecibo radar observations of Titan at 13-centimeter wavelength indicate that most of the echo power is in a diffusely scattered component but that a small specular component is present for about 75% of the subearth locations observed. These specular echoes have properties consistent with those expected for areas of liquid hydrocarbons. Knowledge of the areal extent and depth of any deposits of liquid hydrocarbons could strongly constrain the history of Titan's atmosphere and surface.

Astronomical Phenomena↗
PubMed1994

Classification of impulse radar waveforms using neural networks.

In this paper, it is demonstrated that multilayer neural networks, trained with the backpropagation algorithm and radial basis functions, can classify impulse radar waveforms from three different asphalt-covered bridge decks, each with its own structure. It might be thought that the thickness of asphalt and the depth of concrete over the reinforcing bars would be nearly constant for any one bridge deck; however in practice this is not the case. There are often significant changes in the thickness of the asphalt and the cover over reinforcement. Furthermore, a certain amount of damage to the concrete caused by severe winter climate often produces a random variation in the reflected waveforms obtained from different locations. These factors lead to a significant number of combinations of waveforms that can be obtained from any given structural type of deck. The classification accuracies achieved ranged between 89.9% and 100%. The accuracies achieved after using principal components analysis to reduce the dimensionality of the input data ranged between 95.6% and 100%.

Algorithms↗
PubMed1993

Evaluation of the biological effects of police radar RAMER 7F.

This paper presents results of experiments on the effects of electromagnetic radiation in the millimeter range (frequency 34.0 +/- 0.1 GHz, power density 20 muW/cm2) emitted by a police radar device. Considering the physical properties of the radiation in millimeter range (skin effects), the experiments were carried out on hairless mice. The main physiological parameters tested were body mass, body temperature, peripheral blood, and mass and cellularity of several important organs. Critical organs, the skin, and cornea were examined by electron microscopy. Differentiation ability of hematopoietic cells, progenitors of granulocytes and macrophages, and DNA synthesis in the cornea were compared in irradiated and nonirradiated animals. None of the parameters tested was affected to an extent that would indicate the start of a pathological process or the risk of damage to genetic material.

Animals↗
PubMed2005

Polarimetric laser radar target classification.

Imaging laser radar (ladar) systems have been developed for automatic target identification in surveillance systems. Ladar uses the range value at the target pixels to estimate the target's 3-D shape and identify the target. For targets in clutter and partially hidden targets, there are ambiguities in determining which pixels are on target that lead to uncertainties in determining the target's 3-D shape. An improvement is to use the polarization components of the reflected light. We describe the operation and preliminary evaluation of a polarization diverse imaging ladar system. Using a combination of intensity, range, and degree of polarization, we are better able to identify and distinguish the target from other objects of the same class.

Algorithms↗
PubMed2003

Environmental objections to the PAVE PAWS radar system: a scientific review.

As part of our continental defense system, the United States Air Force has operated a radar system, known generally by the label PAVE PAWS, off of Cape Cod, MA since 1978. Some populated areas in the vicinity of the system are subject to a low level of background radiofrequency radiation from the system, and local citizens' groups have expressed concern that this radiofrequency radiation may affect their health. These concerns have been fueled by presentations and letters by Dr. R. A. Albanese, an applied mathematician at the Air Force Research Laboratory, who has proposed standards by which that PAVE PAWS radiofrequency radiation which is incident on populations should be judged. I discuss those standards that are sufficiently well defined to be subject to analysis and show that they are not based on sound quantitative reasoning.

Environmental Exposure↗
PubMed2000

Ground penetrating radar surveys to locate 1918 Spanish flu victims in permafrost.

The "Spanish Flu" killed over 40 million people worldwide in 1918. Archival records helped us identify seven men who died of influenza in 1918 and were interred in Longyearbyen, Svalbard, Norway, 1,300 km from the North Pole. Ground Penetrating Radar (GPR) was used successfully, in a high-resolution field survey mode, to locate a large excavation with seven coffins, near the existing seven grave markers. The GPR indicated that the ground was disturbed to 2 m depth and was frozen below 1 m. Subsequent excavation showed that: a) the GPR located the position of the graves accurately, b) the coffins were buried less than 1 m deep, and c) that the frozen ground was 1.2 m deep where the coffins were located. The GPR assisted in planning the exhumation, safely and economically, under the high degree of containment required. Virologic and bacteriologic investigations on recovered tissues may give us an opportunity to isolate and identify the micro-organisms involved in the 1918 influenza and expand our knowledge on the pathogenesis of influenza.

Burial↗
PubMed2001

[The study on non-contact detection of breathing and heartbeat based on radar principles].

The paper introduces the design of hardware and software of non-contact detection system for breathing and heartbeat in human body with radar principles and technology. The detection technology is discussed. Under conditions of the illuminating power P < 1 mW and the distance S < 10 m, the non-contact breathing and heartbeat measurement, can be in different positions and with different clothing on the subject. The results show that the system with the technology has a high sensitivity, and is harmless to the health. It is a practicable non-contact detection technology for breathing and heartbeat of human body.

Adult↗
PubMed2003

Real time control of a combined sewer system using radar-measured precipitation--results of the pilot study.

Emschergenossenschaft and Lippeverband have developed a method to use radar-measured precipitation as an input for a real-time control of a combined sewer system containing several overflow structures. Two real-time control strategies have been developed and tested, one is solely volume-based, the other is volume and pollution-based. The system has been implemented in a pilot study in Gelsenkirchen, Germany. During the project the system was optimised and is now in constant operation. It was found, that the volume of combined sewage overflow could be reduced by 5 per cent per year. This was also found in simulations carried out in similar catchment areas. Most of the potential of improvement can already be achieved by local pollution-based control strategies.

Cost Control↗
PubMed2005

Runoff modelling using radar data and flow measurements in a stochastic state space approach.

In urban drainage the estimation of runoff with the help of models is a complex task. This is in part due to the fact that rainfall, the most important input to urban drainage modelling, is highly uncertain. Added to the uncertainty of rainfall is the complexity of performing accurate flow measurements. In terms of deterministic modelling techniques these are needed for calibration and evaluation of the applied model. Therefore, the uncertainties of rainfall and flow measurements have a severe impact on the model parameters and results. To overcome these problems a new methodology has been developed which is based on simple rain plane and runoff models that are incorporated into a stochastic state space model approach. The state estimation is done by using the extended Kalman filter in combination with a maximum likelihood criterion and an off-line optimization routine. This paper presents the results of this new methodology with respect to the combined consideration of uncertainties in distributed rainfall derived from radar data and uncertainties in measured flows in an urban catchment within the Emscher river basin, Germany.

Cities↗
PubMed2006

[Study on second filtering algorithm based on tracing the interfering spectral peaks of radar non-contact life-parameter detection system].

To develop a filtering algorithm which could trace the spectral peaks of the interference and which was used to extract the breath signal with the same band interference in radar non-contact life-detecting system, second filtering algorithm was studied. Through first filtering,the probable interfering spectral peaks (ISP) could be detected by Yule-Walker spectrum estimating and could be located by calculating the coefficients of normalized cross-correlation function according to standard breath signal. Thus the breath signal could be extracted through a second filtering. By using the second filtering algorithm (SFA), the same band interfering spectral peaks with breath signal could be recognized and inhibited. So we conclude that the same band mono-ISP could be inhibited by using SFA and breath signals could be effectively extracted.

Adult↗
PubMed1990

[Hygienic standardization of electromagnetic radiation from two-channel meteorological radar stations].

The study was designed to analyze the impact of the combined electromagnetic fields (EMF) with the wavelength of 10 and 0.8 cm and various levels of energy current density on the central nervous system, metabolic processes, immune resistance and reproductive function. Proceeding from the obtained data maximum allowable levels of EMF produced by the prospective two-channel meteorological++ radars were established.

Animals↗
PubMed1978

Comparison of the vigilance performance of men and women using a simulated radar task.

The present study examined the question of possible sex differences in the ability to sustain attention to a complex monitoring task requiring only a detection response to critical stimulus changes. The visual display was designed to approximate a futuristic, highly automated air traffic control radar display containing computer-generated alphanumeric symbols. There were 26 men and 26 women tested, each over a 2-h session. Sixteen targets appeared on the screen at all times, with 10 signals (a designated change in the alphanumerics) randomly presented during each 0.5 h of the test session. Detection latency to the signals increased significantly during the session, but there was no evidence of any significant differences between the sexes in the magnitude or pattern of this increase. The results are discussed in terms of a general decline in alertness that was apparently equal for both sexes.

Adolescent↗
PubMed1980

Exposure to radio-frequency radiation from an aircraft radar unit.

Two airmen exposed to radio-frequency radiation 38 times above the Air Force permissible exposure level were medically evaluated for physical effects from exposure. Initial anxiety and hypertension were found, but these problems resolved with therapy. This case is reported with the hope that further research will be undertaken to understand the behavioral effects of radar beams on exposed aircrew or ground personnel.

Aerospace Medicine↗
PubMed1994

Radar tomography: a new concept in medical imaging.

There is, at present, no technique for the imaging of internal structures of the human body which is universally applicable to all tissues, has high resolution, is inexpensive, uses no ionizing radiation, creates images in real-time, and can be carried out in the office of a physician or dentist. Radar Tomography (RT), a new concept in medical imaging, has the potential to encompass all of the above criteria, and so curb radiation exposure, inconvenience, discomfort, and cost.

Diagnostic Imaging↗