Peter Kaul

A security assistance system combining person tracking with chemical attributes and video event analysis

Timely recognition of threats can be significantly supported by security assistance systems that work continuously in time and call security personnel in case of anomalous events in the surveillance area. We are describing the concept and the realization of an indoor security assistance system for real-time decision support. The system consists of a computer vision module and a person classification module. The computer vision module provides a video event analysis of the entrance region in front of the demonstrator. After entering the control corridor, the persons are tracked, classified and potential threats are localized inside the demonstrator. Data for person classification are provided by chemical sensors detecting hazardous materials. Due to their limited spatio-temporal resolution, a single chemical sensor cannot localize this material and associate it with a person. We compensate this deficiency by fusing the output of multiple, distributed chemical sensors with kinematical data from laser-range scanners. Considering both the computer vision information and the results of the person classification affords the localization of threats and a timely reaction of security personnel.

Surface chemistry of new As precursors for MOVPE and MOMBE: phenylarsine and tertiarybutylarsine on GaAs(100)

Abstract Surface reactions of PhAs and tBAs on unoxidized and thermally oxidized GaAs(100) were studied in an UHV chamber using a differentially pumped quadrupole mass spectrometer and a molecular beam nozzle. A special sample holder allowed periodic switching between an unoxidized and an oxidized surface to observe small differences in reactivity. The following assumptions are compatible with the experimental results: Adsorption of PhAs or tBAs on GaAs(100) followed by rupture of the As-H bonds is the first step. Most of the organometallic radicals desorb from the surface, a fraction decomposes further by rupture of the As-C bond. The organic radicals react with the surface hydrogen and desorb as benzene and butane or butene, respectively. Low values of the activation energies ( ≤ 0.4 eV) for the different reaction steps suggest a diffusion of PhAs or tBAs on the surface as the rate limiting step for the overall reaction. A comparison of oxidized and unoxidized surfaces exposed to a constant gas flux of PhAs or tBAs revealed a reduced reactivity on the oxidized surface. Thermodesorption experiments with oxidized GaAs(100) surfaces showed that the desorption temperature of GA 2 O decreased from 862 K without tBAs to 835 K in a tBAs flux. During this annealing process a reaction between the surface oxide and organic radicals from the tBAs decomposition seems to form a highly stable contamination layer which was observed by X-ray photoelectron spectroscopy. This contamination of the surface can be avoided by annealing in UHV without any As-species present and monitoring the Ga 2 O flux from the surface with a mass spectrometer because non-stoichiometric evaporation of GaAs occurs only after desorption of the oxide.

A distributed sensing platform for the detection of evaporated hazardous material released from moving sources

Safety and security applications often need to gather data from distributed locations and a multitude of instruments and sensors. We have developed a gas sensing platform that communicates via a wireless sensor network based on IEEE 802.15.4 and/or Ethernet. The data form this network is aggregated via a central server that feeds its information over TCP/IP into subsequent data fusion software. The sensing platform has been equipped with metal oxide gas sensors in order to identify hazardous materials1. A number of these nodes have then been placed along a corridor that persons had to pass in order to enter a restricted area. The data from the chemical sensors were fused with tracking data from laser range scanner and video systems. These tests have shown that it was possible to allocate a chemical contamination of one person within a group of moving people and discriminate between various fire accelerating fuels and solvents. These functions were demonstrated outside the laboratory with a test corridor build in a tent during a military tech‐demo in Eckernforde, Germany.Safety and security applications often need to gather data from distributed locations and a multitude of instruments and sensors. We have developed a gas sensing platform that communicates via a wireless sensor network based on IEEE 802.15.4 and/or Ethernet. The data form this network is aggregated via a central server that feeds its information over TCP/IP into subsequent data fusion software. The sensing platform has been equipped with metal oxide gas sensors in order to identify hazardous materials1. A number of these nodes have then been placed along a corridor that persons had to pass in order to enter a restricted area. The data from the chemical sensors were fused with tracking data from laser range scanner and video systems. These tests have shown that it was possible to allocate a chemical contamination of one person within a group of moving people and discriminate between various fire accelerating fuels and solvents. These functions were demonstrated outside the laboratory with a test corridor b...