Joseph S. Heyman

Ultrasonic device for the noninvasive diagnosis of compartment syndrome

An ultrasonic device for the diagnosis of acute compartment syndrome is described and results on six human cadaveric legs are presented. The ultrasonic device uses a pulsed phase locked loop (PPLL) to measure sub-micrometer displacements of the fascia wall. These displacements occur as a result of volume expansion of the muscle compartment of the lower leg and are related to changes in intramuscular pressure (IMP). In the cadaveric tests, the PPLL detected changes in compartment diameter resulting from IMP changes of 1 mmHg and from infusions of 0.25 ml saline increments. Based on these results, the ultrasonic PPLL appears to have the potential to become a low-cost, portable and noninvasive alternative to current methods for diagnosing acute compartment syndrome.

Nonlinear acoustic concealed weapons detection

The detection of concealed weapons at a distance is a critical security issue that has been a great challenge for different imaging approaches. In this paper, we discuss the use of ultrasonics in a novel way to probe for metallic and nonmetallic materials under clothing. Conventional ultrasonics has problems penetrating clothing and produces false positives from specular reflections. Our approach is to use ultrasonics to create a localized zone where nonlinear interactions generate a lower frequency acoustic wave that is able to penetrate clothing better than direct ultrasonics. The generation of a probing beam for concealed weapons is described in this brief summary showing comparisons of the physical models with the experimental data. An imaging scan of concealed improvised weapons seized by officials at corrections institutes is presented to highlight the value of this approach

Non-linear acoustic concealed weapons detection (CWD)

In this paper we describe an acoustic weapons detection concept that is based on ultrasonics and nonlinear acoustics. An ultrasonic projector is used to create an acoustic field at the site of inspection. The field is composed of multiple ultrasonic waves interacting at the interrogation site. The ultrasonic field creates acoustic interactions at that site which are used as the primary probe. The acoustic field is tailored to excite the target in an optimum fashion for weapons detection. In this presentation, we present aspects of this approach highlighting its ability to confine the interrogation field, create a narrow-band probing field, and the ability to scan that acoustic field to image objects. Ultrasonic propagation parameters that influence the field will be presented as will data of field characteristics. An image obtained with this system will be shown, demonstrating its capability to achieve high resolution. Effects of cloth over a weapon are shown to alter the image, yet not hide the weapon. Luna will report on its most recent findings as to the nature of this detection technology and its ability to generate information important to CWD.

Time-resolved radiation beam profiles in water obtained by ultrasonic tomography

This paper presents a practical ultrasonic system for near real-time imaging of spatial temperature distributions in water caused by absorption of radiation. Initial testing with radiation from a highly attenuated infrared lamp demonstrates that the system is able to map sub-millikelvin temperature changes, thus making it suitable for characterizing dose profiles of therapy-level ionizing radiation beams. The system uses a fan-beam tomographic reconstruction algorithm to invert time-of-flight data derived from ultrasonic pulses produced and detected by a circular array of transducers immersed in water. Temperature dependence of the speed of sound in water permits the conversion of these measured two-dimensional velocity distributions into temperature distributions that indicate the absorbed radiation dose. The laboratory prototype, based on a 128-element transducer array, is used to acquire temperature maps of a 230 mm × 230 mm area every 4 s with sub-millikelvin resolution in temperature and about 5 mm resolution in space. Earlier measurements with a single-channel version of this prototype suggest refinements in signal-conditioning electronics and signal-processing algorithms that would allow the present instrument to resolve temperature changes as low as a few microkelvin. Possible applications include real-time intensity profiling of radiation beams and three-dimensional characterization of the absorbed dose.

Coupling High-Resolution Acoustic Sensor Measurements with Analytical and Numerical Porous Media Solute Transport Modeling

This paper presents the development of a novel acoustic sensor that enhances Doppler approaches to monitor groundwater vector flow. The technique is based on a high-resolution acoustic phase measurement: flowing water introduces a shift in the acoustic velocity component between the transmitter and receiver. By switching the transmitter and receiver modes at periodic intervals, the resulting magnitude of the acoustic phase shift yields the speed of water flow. The high-resolution of the measurement comes from the feedback loop architecture that forces an output toneburst to the transmitter to remain in quadrature with the signal recorded at the receiver. Flow velocity measurements in a column filled with saturated sand (subjected to salt tracer injections), were validated in an ASTM standard constant-head hydraulic test column. Several analytical solution solute transport models and a finite-element numerical model were applied to the test column and compared with measured data. Model predictions obtained...