A5065441983- Acoustic Wave Phenomena Research
- Noise Effects and Management
- Wind and Air Flow Studies
- Aerodynamics and Acoustics in Jet Flows
- Underwater Acoustics Research
- Seismic Waves and Analysis
- Meteorological Phenomena and Simulations
- Hearing Loss and Rehabilitation
- Geophysical Methods and Applications
- Laser-Plasma Interactions and Diagnostics
- Precipitation Measurement and Analysis
- Advanced Fiber Laser Technologies
- Laser Design and Applications
- Ultrasonics and Acoustic Wave Propagation
- Optical and Acousto-Optic Technologies
- Structural Health Monitoring Techniques
- Ocean Waves and Remote Sensing
- Advanced Optical Sensing Technologies
- Health disparities and outcomes
- Laser-induced spectroscopy and plasma
- Planetary Science and Exploration
- Image and Signal Denoising Methods
- Fluid Dynamics and Vibration Analysis
- Flow Measurement and Analysis
- Climate Change and Health Impacts
Cold Regions Research and Engineering Laboratory
2016-2024
United States Army
2015-2024
U.S. Army Engineer Research and Development Center
2016-2024
Columbia University
2022
Atmospheric and Environmental Research
2021
United States Naval Academy
2021
United States Department of the Army
2020
University of Nebraska–Lincoln
2010-2012
University of Glasgow
1997-2007
JDSU (United States)
2007
<h3>Abstract</h3> <b>Objectives:</b> To assess the influence of socioeconomic position over a lifetime on risk factors for cardiovascular disease, morbidity, and mortality from various causes. <b>Design:</b> Prospective observational study with 21 years follow up. Social class was determined as manual or non-manual at three stages participants9 lives: social their father9s job, first job time screening. A cumulative indicator constructed, ranging all life to stages. <b>Setting:</b> 27...
BACKGROUND: In all 8353 women and 7058 men aged 45-64 took part in the Renfrew/Paisley survey 1972-1976. They formed a prospective cohort study of general population West Scotland; an area with high ischaemic heart disease (IHD) mortality rates. The objective this was to investigate three indicators pre-existing IHD determine how they predicted subsequent females compared males. METHODS: Pre-existing ascertained by Rose Angina questionnaire, question on severe chest pain indicating evidence...
Sound propagation along vertical and slanted paths through the near-ground atmosphere impacts detection localization of low-altitude sound sources, such as small unmanned aerial vehicles, from ground-based microphone arrays. This article experimentally investigates amplitude phase fluctuations acoustic signals propagating paths. The experiment involved nine microphones on three horizontal booms mounted at different heights to a 135-m meteorological tower National Wind Technology Center...
Atmospheric turbulence causes acoustic signals to fluctuate and diminishes their coherence. These phenomena are important in applications such as source localization sonic boom propagation. This article provides formulations for the spatial, cross-frequency, temporal coherences of narrowband propagating over vertical slanted paths atmosphere. Formulations single- two-point distributions also overviewed. The theoretical compared with data from a comprehensive sound propagation experiment...
Jigsaw three-dimensional (3D) imaging laser radar is a compact, light-weight system for highly obscured targets through dense foliage semi-autonomously from an unmanned aircraft. The uses gimbaled sensor operating in spot light mode to illuminate cued target, and autonomously capture produce the 3D image of hidden under trees at high voxel resolution. With our MIT Lincoln Laboratory team members, has been integrated into geo-referenced 12-inch gimbal, used airborne data collections UH-1...
Many outdoor sound propagation models exist, ranging from highly complex physics-based simulations to simplified engineering calculations, and more recently, flexible statistical learning methods. Several are evaluated by using a particular model, namely, Crank-Nicholson parabolic equation (CNPE), as benchmark. Narrowband transmission loss values predicted with the CNPE, based upon simulated data set of meteorological, boundary, source conditions, act observations. In conditions span...
To assess the value of psychosocial risk factors in discriminating between individuals at higher and lower coronary heart disease, using prediction equations.
A variety of probability density functions (pdfs) have been proposed for scattered signals, which varying analytical advantages and ranges physical applicability. We discuss here modeling with a compound pdf, in basic describing the underlying scattering process, has uncertain parameters or is modulated by variability environment. The modulating pdf are termed hyperparameters. Some previous examples formulations include K-distribution, strong (exponential pdf) gamma mean signal power,...
Sound propagation through atmospheric turbulence is important in many applications such as localization of low flying aircraft, sonic boom disturbances, and auralization aircraft during takeoff landing. This article extends an isotropic model the boundary layer to account for ground blocking buoyancy-produced velocity fluctuations. The extended, anisotropic needed correctly predict effect largest eddies on statistical characteristics sound signals. geometrical acoustics are then employed...
Conventional numerical methods can capture the inherent variability of long-range outdoor sound propagation. However, computational memory and time requirements are high. In contrast, machine-learning models provide very fast predictions. This comes by learning from experimental observations or surrogate data. Yet, it is unknown what type data most suitable for machine-learning. study used a Crank-Nicholson parabolic equation (CNPE) generating The CNPE input were sampled Latin hypercube...
This study examines a cohort in which individuals of privileged socio-economic position report greater psychological stress. We have previously shown this that stress is unrelated to coronary heart disease as measured by hospital discharge diagnosis and cause-specific death. In contrast, hospitalization for cardiovascular conditions not requiring mandatory admission were associated. hypothesized psychosocial factors, particular reporting tendency, are the likely mediator association, present...
A variety of probability density functions (pdfs) have been proposed for scattered signals, which varying analytical advantages and ranges physical applicability. We discuss here situations modeled by a compound pdf, in basic attributable to the underlying scattering process, has uncertain parameters or is modulated variability environment. The modulating pdf are termed hyperparameters. Some previous examples formulations include K-distribution, strong (exponential pdf) gamma mean signal...
Many outdoor sound propagation models exist, ranging from highly complex physics-based simulations to simplified engineering calculations. More recently, flexible statistical methods have become available, which offer the capability predict propagation, given a training dataset. Among variety of modeling approaches, range incorporated physics varies none, as in learning methods, comprehensive considerations for physical models. Engineering vary level physics, oftentimes resorting heuristic...
Statistical distributions of urban noise levels are influenced by many complex phenomena, including spatial and temporal variations in the source level, multisource mixtures, propagation losses, random fading from multipath reflections. This article provides a broad perspective on varying impacts these phenomena. Distributions incorporating averaging (e.g., gamma noncentral Erlang) tend to be negatively skewed logarithmic (decibel) axes but can positively if process is strongly modulated...
Laser-induced shockwaves in air are ideal for model studies of blast waves, and nonlinear propagation effects. Focusing a sufficiently energetic laser pulse to small spot size causes the surrounding form into rapidly expanding plasma. After finite time shockwave detaches from plasma boundary adiabatically propagates. For times exceeding tens microseconds, past generally measure characteristics with condenser microphones. General features can be deduced these measurements, however, presence...
This paper describes a comprehensive modeling approach for infrasonic (sub-audible acoustic) signals, which starts with an accurate representation of the source spectrum and directivity, propagates signals through environment, senses processes at receiver. The calculations are implemented within EASEE (Environmental Awareness Sensor Emitter Employment), is general software framework impacts terrain weather on target signatures performance diverse range battlefield sensing systems, including...
The prediction accuracy of outdoor sound is in large part limited by uncertainties the state atmosphere. These can potentially be reduced inferring scaling parameters atmospheric surface layer from wind noise. Screened microphones sense noise as a result mean flow, turbulent eddy interaction with windscreen, and pressure fluctuations within flow. Under conditions terrain homogeneity quasi-steadiness, Monin-Obukhov similarity theory (MOST) states that only handful governs dynamics layer. This...
The indirect measurement of shock waveforms by acousto-optic sensing requires a method to reconstruct the field from projected data. Under assumption spherical symmetry, one approach is Abel inversion integral transform. When modality measures change in optical phase difference time derivative, as for heterodyne Mach–Zehnder interferometer, e.g., laser Doppler vibrometer, reconstructed fluctuating refractive index derivative. A technique derived that reconstructs directly assuming plane wave...
Noncontact optical methods (e.g., shadowgraphy, schlieren, and interferometry) allow visualization of propagating shock waves, avoid sensor-field interaction, retain the potential for very high bandwidth. The heterodyne Mach-Zehnder interferometer produces quantifiable noncontact samples accumulated phase shifts induced by a wave, as viewed through its beam projection. This instrument is commercially available Laser Doppler Vibrometer (LDV). For shocked wave fields in air obeying spherical...
Current practices for assessing the thickness of growing ice include drilling and coring. This is inherently risky motivates use a stand-off method. Laser Doppler vibrometry potential technique, however, interpretation vibrometer signals must be informed by physical understanding subjected to mechanical vibrations. The vibrational response growing, thin largely unknown. For thick ice, adequate predictions assumes behaves as an elastic plate. It hypothesized that responds in fashion somewhere...
The impacts of turbulence on sound propagation in the atmospheric boundary layer (ABL) are important many practical applications such as acoustic source localization, sonic boom propagation, and auralization flying aircraft. However, can vary dramatically response to changing meteorological conditions. To address this issue, a spectral model has been introduced that captures complexities generation by wind shear, buoyancy instabilities, ground blocking ABL. An experiment vertical slanted...
Current models for the wind noise reduction (WNR) of microphone windscreens in atmospheric turbulence generally work under assumption a homogeneous surface pressure averaging theorem. Under this theorem, pressures should average such way that spectrum at low wavenumbers relative to windscreen dimension approach an unscreened microphone. Contrasting this, experiments have actually observed significant WNR these wavenumbers. In work, we examine Rapid Distortion Theory model linking turbulent...