A feedforward control algorithm for active noise control based on the recursive estimation of a generalized finite impulse response (FIR) filter is presented in this paper. Recursive least square estimation (RLSE) with variable forgetting factors is applied to a commercial air ventilation silencer to provide the online estimation of the generalized finite impulse response (FIR) filter to obtain...

Carpeted bedrooms of 36 asthmatic children were monitored to examine the mass concentration of indoor aerosol particulate matter (PM), from non-smoking households, and the effect high efficiency particle arresting (HEPA) air filtration had on PM concentration. Concurrent indoor and outdoor monitoring was also undertaken. Mass concentration was determined gravimetrically using time weighted conc...

In modern systems for air surveillance, it is important to have a high quality situation assessment. SAAB has a system for air surveillance, and in this thesis possible improvements of the tracking performance of this system are explored. The focus has been on improving the tracking of highly maneuverable targets observed with low sampling rate. To evaluate improvements of the tracking performa...

Devices for the measurement of airborne fiber concentration currently existing on the market show significant disadvantages. Due to e.g. multi-step measurement principles or bulky design, existing devices are not capable to be used for specific applications. Knowledge of airborne fiber concentration is essential to determine operation conditions and air quality in e.g. textile mills, museums or...

introduction: chlorine gas producting by mercury cell (chlor-alkali) is one of the most widely used methods. leakage and vaporizing mercury from cells can cause occupational poisoning. mercury is the most toxic non-radioactive heavy metal ; therefore measurement of air concentration of this metal is very important. the aim of this research was measuring ambient air mercury concentration in a pe...

UNLABELLED A study was carried out to investigate the feasibility of achieving ultra low respirable suspended particulates (RSP) in commercial offices without major modification of existing ventilation systems by enhancing the particulates removal efficiency of existing central ventilation systems. Four types of filters which include pre-filters, cartridge filters, bag filters and high efficien...

Microbial aerosols are known to be created and disseminated in dental operating rooms (DOR's) in quantities sufficient to raise the possibility of cross infection. The purpose of this study was to evaluate the effectiveness of high efficiency particulate air (HEPA) filters in reducing the concentration of airborne microorganisms. Tests were made in DOR's of 1600-, 1800-, and 3240-ft 3 capacity ...

The Bi-Air (BA) dual-trace 25 mm filter cassette was described, and its performance for the collection of Aspergillus/Penicillium (Asp/Pen) and Stachybotrys type spores in a clam-air settling chamber was compared to that of the Air-O-Cell (AOC) cassette. The BA produced duplicate sample traces, the sample traces were confined to two small, welldefined areas on the filter, and the small size of ...

Since diesel exhaust gas has more ambient air pollutants such as NOx and particulate matters (PM) including soot, the special treatment for exhaust emission standards is needed. Recently, a diesel particulate filter (DPF) has been developed to reduce PM in the after-treatment of exhaust gas. However, since the structure of the filter is small and complex, it is impossible to examine the phenome...

The concentration of hydrogen peroxide (H2O2) in exhaled air has been reported to be elevated in asthma and chronic obstructive pulmonary disease (COPD), but results are inconsistent and difficult to reproduce. As H2O2 occurs in ambient air, we examined its association with exhaled H2O2 in human subjects. Exhaled breath condensate (EBC) of 12 COPD patients and nine healthy control subjects was ...