Analysis of Radar Doppler Signature from Human Data

This paper presents the results of time (autocorrelation) and time-frequency (spectrogram) analyses of radar signals returned from the moving human targets. When a radar signal falls on the human target which is moving toward or away from the radar, the signals reflected from different parts of his body produce a Doppler shift that is proportional to the velocity of those parts. Moving parts of the body causes the characteristic Doppler signature. The main contribution comes from the torso which causes the central Doppler frequency of target. The motion of arms and legs induces modulation on the returned radar signal and generates sidebands around the central Doppler frequency, referred to as micro-Doppler signatures. Through analyses on experimental data it was demonstrated that the human motion signature extraction is better using spectrogram. While the central Doppler frequency can be determined using the autocorrelation and the spectrogram, the extraction of the fundamental cadence frequency using the autocorrelation is unreliable when the target is in the clutter presence. It was shown that the fundamental cadence frequency increases with increasing dynamic movement of people and simultaneously the possibility of its extraction is proportional to the degree of synchronization movements of persons in the group

Prospects of the WSR-88D Radar for Cloud Studies

This is the publisher's version, also available electronically from http://journals.ametsoc.org/doi/abs/10.1175/2010JAMC2303.1.Sounding of nonprecipitating clouds with the 10-cm wavelength Weather Surveillance Radar-1988 Doppler (WSR-88D) is discussed. Readily available enhancements to signal processing and volume coverage patterns of the WSR-88D allow observations of a variety of clouds with reflectivities as low as −25 dBZ (at a range of 10 km). The high sensitivity of the WSR-88D, its wide velocity and unambiguous range intervals, and the absence of attenuation allow accurate measurements of the reflectivity factor, Doppler velocity, and spectrum width fields in clouds to ranges of about 50 km. Fields of polarimetric variables in clouds, observed with a research polarimetric WSR-88D, demonstrate an abundance of information and help to resolve Bragg and particulate scatter. The scanning, Doppler, and polarimetric capabilities of the WSR-88D allow real-time, three-dimensional mapping of cloud processes, such as transformations of hydrometeors between liquid and ice phases. The presence of ice particles is revealed by high differential reflectivities and the lack of correlation between reflectivity and differential reflectivity in clouds in contrast to that found for rain. Pockets of high differential reflectivities are frequently observed in clouds; maximal values of differential reflectivity exceed 8 dB, far above the level observed in rain. The establishment of the WSR-88D network consisting of 157 polarimetric radars can be used to collect cloud data at any radar site, making the network a potentially powerful tool for climatic studies

False Alarm Analysis of the CATM-CFAR in Presence of Clutter Edge

This paper presents a false alarm analysis of the cell-averaging-trimmed-mean constant false alarm rate (CATM-CFAR) detector in the presence of clutter edge. Structure of the CATM-CFAR detector is described briefly. Detection curves for optimal, CATM, cell-averaging (CA), trimmed-mean (TM) and ordered-statistic (OS) CFAR detectors has been analyzed and compared for desired probability of false alarm and determined size of the reference window. False alarm analysis of the CATM-CFAR in case of clutter with constant clutter-to-noise ratio has been conducted. Also, comparative false alarm analysis of CATM and some of well known CFAR detectors is carried out and results are presented

Tesla’s research in the field of mechanical engineering focused on fountains design

Nikola Tesla (1856-1943) made numerous inventions and discoveries in the field of electricity that form the basis of new scientific and technological breakthroughs, started in the late 19th century, without which our present life could not be imagined. Tesla’s abundant and interesting creative activity in the field of mechanical engineering has only sporadically been quoted in the greatest number of biographical depictions of his life and opus. Accordingly, the terms such as e.g. turbines, pumps, fountains, speedometers or aeroplanes, often act confusing even on a connoisseur, deemed to be at least averagely informed about Tesla’s inventions and discoveries. One of those less known achievements is his patent for a fountain. This invention of Tesla’s is different from usual solutions applied to fountains and aquariums of that time, where the fluid was sprayed or jetted with appropriate devices for decorative purposes. The abundant documents in the archives preserved at the Nikola Tesla Museum in Belgrade demonstrate Tesla’s great engagement in this, at first glance less significant, segment of his creative activity. This paper presents Tesla’s work and achievements in the field of fountains. Using the original archival documents, design solutions, technical drawings, calculations, correspondence with companies and individuals, magazine articles and various brochures, the authors examine the scope of Tesla’s research in this less known field. The authors also provide CAD models based on some of Tesla’s original drawings of the fountains archived as a part of his legacy at the Nikola Tesla Museum in Belgrade

Tie-rods of the bucket wheel excavator slewing superstructure: A study of the eye plate stress state

Tie-rods of the bucket wheel and counterweight booms are vital parts of the bucket wheel excavator slewing superstructure. This paper is dedicated to the problem of identifying the stress state of the critical cross-section ('net section') of the eye plates on these tie-rods. It presents the results of the experimental and numerical investigations carried out on the eyebar model. The results show the appearance of a plastic deformation in the zone near the contour of the hole even when the eye is subjected to the loads within the range of the permissible loads prescribed by the standard DIN 22261-2. Plastification in the eye net section occurs across the full thickness of the plate, but it does not jeopardize the integrity of the structure. The stress value in the eye net section, calculated in accordance with the standard DIN 22261-2, is significantly lower than the actual stress values around the hole and serves only as a comparative value for the static strength proof for the eye

Small intestinal bacterial overgrowth and nonalcoholic fatty liver disease diagnosed by transient elastography and liver biopsy

Background: We aimed to determine if there was a higher incidence of small intestinal bacterial overgrowth (SIBO) in nonalcoholic fatty liver disease (NAFLD) than in patients without NAFLD. Moreover, we assessed whether patients with significant fibrosis (SF) had a higher incidence of SIBO compared to patients with non-significant or no liver fibrosis. Methods: NAFLD was diagnosed in 117 patients by using Fibroscan with a controlled attenuation parameter (CAP) as well as liver biopsy (LB). SIBO was defined by esophagogastroduodenoscopy with an aspiration of the descending duodenum. Results: Patients with nonalcoholic steatohepatitis (NASH) and those with SF on LB had a significantly higher incidence of SIBO than patients without NASH and those without SF, respectively (p<0.05). According to histological characteristics, there was a higher proportion of patients in the SIBO group with higher steatosis and fibrosis grade, lobular and portal inflammation, and ballooning grade (p<0.001). In multivariate analysis, significant predictors associated with SF and NASH were type 2 diabetes mellitus (T2DM) and SIBO. Moreover, in multivariate analysis, significant predictors that were independently associated with SIBO were T2DM, fibrosis stage, and ballooning grade (OR 8.80 (2.07-37.37), 2.50 (1.16-5.37) and 27.6 (6.41-119), respectively). The most commonly isolated were gram-negative bacteria, predominantly Escherichia coli and Klebsiella pneumoniae. Conclusion: In this relatively large population of patients, we used a gold standard for both SIBO (quantitative culture of duodenum's descending part aspirate) and NAFLD (LB), and we demonstrated that NASH patients and those with SF had a higher incidence of SIBO. Moreover, significant predictors independently associated with SIBO were T2DM, fibrosis stage, and ballooning grade. Although TE is a well-investigated method for steatosis and fibrosis detection, in our study, independent predictors of SIBO were histological characteristics of NAFLD, while elastographic parameters did not reach statistical significance

The burden of adverse childhood experiences when coping and adjusting to COVID-19 pandemic.

Adverse Childhood Experiences (ACE) are important stressors, impinging the response to other psychological challenges during life. People exposed to ACE tend to be more vulnerable to develop psychiatric disorders and are more prone to adjustment difficulties when facing the extreme stress, uncertainty, and health-related risk of the COVID-19 pandemic. Objective: To disentangle associations between coping strategies, resilience and protective factors, mental health risk, and number and type of ACE. Method: An online survey launched by the ESTSS in eleven countries permits the assessment of protective and resilience factors, coping behaviour, and maladaptive adjustment amidst the COVID-19 pandemic. Evaluation of mental health risk was performed using standardized instruments including measures of depression, anxiety, symptoms of adjustment disorder (ADNM-8), and posttraumatic disorder (PC-PTSD). The presence of ACE was screened in all participants who described the type and number of traumatic experiences experienced during childhood. The analysis will elucidate the presence of ACE in different individuals grouped by demographic characteristics, to foresee: 1) the most predominant variables; 2) if ACE scores relate to mental health-derived risks or resilience. Results: Preliminary results in ten of the participating countries showed variable frequencies of reported ACE in the different populations. The incidence of at least one ACE varies between countries. Conclusions: Childhood adversity may be considered as a cumulative burden and risk for mental disorders and adjustment difficulties when dealing with pandemic-related multiple challenges or may enhance protective mechanisms sustaining the wellbeing of specific subpopulations