Aeronix (United States)

In recent years the military has been developing mobile Multiple-Input Multiple-Output (MIMO) technology. MIMO communications are attractive due to enhanced performance in urban, high multi-path environments which can cause substantial performance degradation in Single Input Single Output (SISO) communications. In this paper, results of a MIMO mobile network of 2 antenna MIMO radio systems employing spatial diversity, with four nodes in a hub-spoke configuration are given. The purpose was to validate MIMO mobile network performance over that of a SISO network. The experiments were conducted in several different environments such as reduced line of sight, heavily obstructive with buildings and dense foliage and high multipath environments and for On-The-Move (OTM) and At-The-Halt (ATH) test scenarios. Tests were conducted in SISO, MIMO and receiver diversity (RXD) modes for comparison and to show backwards compatibility to SISO radios. The paper highlights the advantages of the MIMO mobile network technology, showing improved throughput, reliable communications and coverage extension in mobile and reduced line of sight scenarios. The results consistently showed on average a 10% to 15% throughput improvement in MIMO over SISO given the same transmit power and operating range.

Abstract Aeration for water treatment, the transfer of oxygen, O2, from air to water, is well‐studied. The basic purpose of aeration, used primarily for the treatment of wastewater, is to improve water quality for subsequent usage. Aeration can bring about the physical removal of taste‐ and odor‐producing substances such as hydrogen sulfide, H2S, and other volatiles as well as the chemical removal of metals (iron, manganese), gases (hydrogen sulfide), and other compounds (organics and inorganics) through oxidation and settling. Additionally, aeration is used extensively for the biological oxidation of both domestic and industrial organic wastes. The function of aeration in a wastewater treatment system is to maintain an aerobic condition. Methods developed to estimate the oxygen demand are biochemical oxygen demand (BOD), chemical oxygen demand (COD), total oxygen demand (TOD), total organic carbon (TOC), and theoretical oxygen demand (ThOD). The oxygen transfer rate for aerators is normally reported at standard conditions. Thus, in order to make meaningful comparisons, the oxygen required for treatment under working or field conditions should be adjusted to standard conditions.

Finite element and boundary element calculations are combined to predict the flow noise radiated from a 1/10th-scale model of an aerodynamic cover used around the pantograph on a train at 250 km h−1. The solutions of the unsteady air flow over the cover and the resulting sound propagation are divided into two parts in order to keep the problem tractable. First the unsteady fluid flow is solved using large-eddy simulation (LES). The pressure histories on the cover are then used to predict the radiated sound, using a boundary element method to solve the Helmholtz equation. The result thus leans heavily on assumptions about the coupling of the two solutions, the propagation of sound in a disturbed medium and the efficacy of LES. The predicted sound pressure levels are compared with experimental measurements made in an anechoic wind tunnel. © 1997 John Wiley & Sons, Ltd.