Modelling the air cleaning performance of negative air ionisers in ventilated rooms

Negative air ionisers have seen increasing use as devices for improving indoor air quality, including some success in clinical environments for reducing the transmission of infection. This study uses a ventilation model and a CFD model to examine the physical effects of negative ionisers in indoor environments. The results demonstrate how the negative ion distribution and electric field due to an ioniser are influenced by both the room airflow and the ion generation rate. It is shown that ion concentrations greater than 1010 ions/m3 are necessary for the electrical effects to be significant. The effect on particles is also considered, with the results demonstrating that the ioniser will only increase the deposition of particles when the particle concentration is high enough to contribute to the space charge in the room

Modelling the air cleaning performance of negative air ionisers in ventilated rooms

Negative air ionisers have seen increasing use as devices for improving indoor air quality, including some success in clinical environments for reducing the transmission of infection. This study uses a ventilation model and a CFD model to examine the physical effects of negative ionisers in indoor environments. The results demonstrate how the negative ion distribution and electric field due to an ioniser are influenced by both the room airflow and the ion generation rate. It is shown that ion concentrations greater than 1010 ions/m3 are necessary for the electrical effects to be significant. The effect on particles is also considered, with the results demonstrating that the ioniser will only increase the deposition of particles when the particle concentration is high enough to contribute to the space charge in the room

Apollo PLSS: Environmental control of the smallest manned space vehicle

The production of a portable life support system (PLSS) and associated backup equipment for supporting an astronaut working outside of the lunar module (LM) either in space or on the lunar surface is reported. Described are the system, the philosophy behind its design, basic requirements imposed on the system, and some of the evolutionary processes that led to the present configuration

Physical Computation, P/poly and P/log*

In this paper we give a framework for describing how abstract systems can be used to compute if no randomness or error is involved. Using this we describe a class of classical "physical" computation systems whose computational capabilities in polynomial time are equivalent to P/poly. We then extend our framework to describe how measurement and transformation times may vary depending on their input. Finally we describe two classes of classical "physical" computation systems in this new framework whose computational capabilities in polynomial time are equivalent to P/poly and P/log*

Considerations of electron beam propagation from space vehicles

Theoretical analysis of electron beam array propagation from spacecraf

Radiation testing of composite materials, in situ versus ex situ effects

The effect of post irradiation test environments on tensile properties of representative advanced composite materials (T300/5208, T300/934, C6000/P1700) was investigated. Four ply (+ or - 45 deg/+ or - 45 deg) laminate tensile specimens were exposed in vacuum up to a bulk dose of 1 x 10 to the 10th power rads using a mono-energetic fluence of 700 keV electrons from a Van de Graaff accelerator. Post irradiation testing was performed while specimens were being irradiated (in situ data), in vacuum after cessation of irradiation (in vacuo data), and after exposure to air (ex situ data). Room temperature and elevated temperature effects were evaluated. The radiation induced changes to the tensile properties were small. Since the absolute changes in tensile properties were small, the existance of a post irradiation test environment effect was indeterminate

Electron accelerator for Aerobee 350 rocket - Description, development and flight performance Final report

Aerobee-borne electron accelerators for ejecting electron beams into upper atmospher

Critical phenomena in globally coupled excitable elements

Critical phenomena in globally coupled excitable elements are studied by focusing on a saddle-node bifurcation at the collective level. Critical exponents that characterize divergent fluctuations of interspike intervals near the bifurcation are calculated theoretically. The calculated values appear to be in good agreement with those determined by numerical experiments. The relevance of our results to jamming transitions is also mentioned.Comment: 4 pages, 3 figure

Modelling the air cleaning performance of negative air ionisers in ventilated rooms

Negative air ionisers have seen increasing use as devices for improving indoor air quality, including some success in clinical environments for reducing the transmission of infection. This study uses a ventilation model and a CFD model to examine the physical effects of negative ionisers in indoor environments. The results demonstrate how the negative ion distribution and electric field due to an ioniser are influenced by both the room airflow and the ion generation rate. It is shown that ion concentrations greater than 1010 ions/m3 are necessary for the electrical effects to be significant. The effect on particles is also considered, with the results demonstrating that the ioniser will only increase the deposition of particles when the particle concentration is high enough to contribute to the space charge in the room

The Company You Keep: Investment Manager Clientele and Mutual Fund Performance

This paper examines how the composition of an investment adviser’s client base (identified via Form ADV filings) relates to the performance of its mutual funds. Investment advisers catering to institutional clients realize statistically and economically superior risk-adjusted mutual fund performance relative to retail-oriented advisers. The findings are consistent with the empirical predictions of the Gârleanu and Pedersen (2018) model for asset management markets. The results suggest that institutional clients can identify differences in investment manager skill, particularly in market segments where retail mutual fund investors face higher search costs