Acoustic tamper detection sensor with very low false alarm rate

We describe a device designed to detect interference (vandalism or tampering) by acoustic means. The design employs both a piezoelectric vibration transducer and a common microphone in a novel mechanical arrangement. In contrast to conventional acoustic sensors that simply respond to vibrations above a threshold, this design analyses the outputs of the two to trigger an alarm. The method confers a near-zero susceptibility to triggering by external loud noises. No complex calculations are required so that only a low-cost, embedded microcontroller is required and the whole sensor can be very cheap. Extreme sensitivity can be achieved with little risk of false alarms

A Multiple Migration and Stacking Algorithm Designed for Land Mine Detection

This paper describes a modification to a standard migration algorithm for land mine detection with a ground-penetrating radar (GPR) system. High directivity from the antenna requires a significantly large aperture in relation to the operating wavelength, but at the frequencies of operation of GPR, this would result in a large and impractical antenna. For operator convenience, most GPR antennas are small and exhibit low directivity and a wide beamwidth. This causes the GPR image to bear little resemblance to the actual target scattering centers. Migration algorithms attempt to reduce this effect by focusing the scattered energy from the source reflector and consequentially improve the target detection rate. However, problems occur due to the varying operational conditions, which result in the migration algorithm requiring vastly different calibration parameters. In order to combat this effect, this migration scheme stacks multiple versions of the same migrated data with different velocity values, whereas some other migration schemes only use a single velocity value

Anomaly Detection in Hyperspectral Imagery: Comparison of Methods Using Diurnal and Seasonal Data

The use of hyperspectral imaging is a fast growing field with many applications in the civilian, commercial and military sectors. Hyperspectral images are typically composed of many spectral bands in the visible and infrared regions of the electromagnetic spectrum and have the potential to deliver a great deal of information about a remotely sensed scene. One area of interest regarding hyperspectral images is anomaly detection, or the ability to find spectral outliers within a complex background in a scene with no a priori information about the scene or its specific contents. Anomaly detectors typically operate by creating a statistical background model of a hyperspectral image and measuring anomalies as image pixels that do not conform properly to that given model. In this study we compare the performance over diurnal and seasonal changes for several different anomaly detection methods found in the literature and a new anomaly detector that we refer to as the fuzzy cluster-based anomaly detector. Here we also compare the performance of several anomaly-based change detection algorithms. Our results indicate that all anomaly detectors tested in this experimentation exhibit strong performance under optimum illumination and environmental conditions. However, our results point toward a significant performance advantage for cluster-based anomaly detectors in the presence of adverse environmental conditions

Risks, designs, and research for fire safety in spacecraft

Current fire protection for spacecraft relies mainly on fire prevention through the use of nonflammable materials and strict storage controls of other materials. The Shuttle also has smoke detectors and fire extinguishers, using technology similar to aircraft practices. While experience has shown that the current fire protection is adequate, future improvements in fire safety technology to meet the challenges of long duration space missions, such as the Space Station Freedom, are essential. All spacecraft fire protection systems, however, must deal with the unusual combustion characteristics and operational problems in the low gravity environment. The features of low gravity combustion that affect spacecraft fire safety, and the issues in fire protection for Freedom that must be addressed eventually to provide effective and conservative fire protection systems are discussed