background: volatile organic compounds (vocs) are human-made chemicals widely spread in the environment and produced by petrochemical industries and petroleum refineries. the aim of this research was to evaluate the distribution of vocs in the ambient air of mahshahr petrochemical complex, iran. methods: this study was a cross-sectional research performed in 2009. we used the method numbered 15...

acetonitrile used as a solvent in manufactures and affects to central nervous system from inhalation exposure. the aim of this study was to develop a micro-solid phase extraction method for  the determination of acetonitrile in the air matrix. the sampling was performed with a small diameter fused silica fiber coated with a thin film of stationary phase and was subsequently desorbed and analyze...

phase sensitive detector described here has two principal applications: a- to produce a d.c out put proportional to- the amplitude of an incoming a,c signal and indicate, by the outut polarity, the phase of the signal with respect to an internal reference. b- to detect the presence of a signal of known phase and frequency which would otherwise be lost in «background noise» and to measure its am...

in this paper a new algorithm is presented for coherent radar detection of targets, when distribution of the interference (clutter and noise) is non-gaussian. the neyman-pearson criterion is used for optimal detection and several successive received samples from a radar range cell are used for detection in the same cell. on the basis of recent empirical evidences, the interference distribution ...

Hydroxyl (OH) radicals play a vital role in maintaining the oxidizing capacity of the atmosphere. To understand variations in OH radicals both source and sink terms must be understood. Currently the overall sink term, or the total atmospheric reactivity to OH, is poorly constrained. Here, we present a new on-line method to directly measure the total OH reactivity (i.e. total loss rate of OH rad...

A semi-continuous and automated method for quantifying atmospheric ammonia at the parts per billion level has been developed. The instrument consists of a high efficiency diffusion scrubber, an electrolytic on-line anion exchange device, and a conductivity detector. Water soluble gases in sampled air diffuse through the porous membrane and are absorbed in an absorbing solution. Interferences ar...

The Pierre Auger Observatory consists of a detector system to study ultrahigh-energy cosmic rays. These rays can be detected only through the observation extensive air showers. hybrid detection showers at is based on Surface Detector (SD) – an array about 1660 water-Cherenkov detectors, and Fluorescence Detector, with 27 telescopes overlooking SD. Recently, upgrade was initiated, called AugerPr...

Human occupancy detection and localization are important in a variety of smart building applications including building security, assisted living monitors, and energyefficient heating ventilation and air cooling and lighting. Current implementation of such systems is limited by motion– sensor technologies, e.g., passive infrared (PIR) and ultrasonic sensors, which substitute as occupancy detect...

We posit that each of us is unique in our use of computer systems. It is this uniqueness that we leverage in this paper to “continuously authenticate users” while they use web software. We build an n-gram model of each user’s interactions with software. This probabilistic model essentially captures the sequences and sub-sequences of user actions, their orderings, and temporal relationships that...

In this paper, we introduce a two−dimensional Generalized Autoregressive Conditional Heteroscedasticity (GARCH) model for clutter modeling and anomaly detection. The one−dimensional GARCH model is widely used for modeling financial time series. Extending the one−dimensional GARCH model into two dimensions yields a novel clutter model which is capable of taking into account important characteris...