3,935 research outputs found
Design and Modeling of the Properties of the Servomechanism for a Mobile Free Space Optical Link
The paper deals with the design of a tracking system determined for mobile free space optical link communication system. The paper also contains description of two-step method of the optical-axes pointing process, description of the basic properties of servomechanisms and results of the simple simulation of the tracking-system function model. The entire model consists of four partial models, i.e. of model of trajectory, model of uneven road surface, model of vehicle and model of horizontal and vertical servos. Results of these simulations will be used to give precision to the construction design of the mobile free space optical link station and its servomechanisms
Calculation of Angular Deflection Limits of a Mobile Free-Space Optical Link Beam
The paper describes the effect of optical beam angular deflection on the power received by the receiver of a mobile free-space optical (FSO) link. Permissible fluctuations in the power received were studied on a steady model of the FSO link. It was assumed that these fluctuations were caused by oscillations of the optical beam across the receiver aperture. The formula for beam angular deflection limit was derived for two different types of optical intensity profile. The task was solved for two different types of atmosphere. The first type of atmosphere was considered a homogeneous and lossless environment. In the second type, atmospheric radiation attenuation was included in the calculations. Also, this article includes graphs of dependencies of the angular deflection limits upon the distance between the link stations
Energy storage-boiler tank
Activities performed in an effort to demonstrate heat of fusion energy storage in containerized salts are reported. The properties and cycle life characteristics of a eutectic salt having a boiling point of about 385 C (NaCl, KCl, Mg Cl2) were determined. M-terphenyl was chosen as the heat transfer fluid. Compatibility studies were conducted and mild steel containers were selected. The design and fabrication of a 2MWh storage boiler tank are discussed
Annoyance due to noise and air pollution to the residents of heavily frequented streets
The residents of different streets with varying traffic density and building density were questioned about annoyance due to traffic noise and air pollution. Results show that annoyance felt is dependent not only on the measured noise levels and/or air pollution concentrations, but that there do exist interactions between the residential quarters and annoyance. These interactions should be considered when fixing the limits and standards
A Modelling Approach for Evaluating Agri-Environmental Policies at Sector Level
This paper presents a new approach to evaluate the cost effectiveness of agri-environmental policies at sector level. Policy uptake, cumulative environmental effects and public expenditure are identified as the main determinants of cost-effectiveness. On the basis of the sector-consistent, comparative-static, farm group model FARMIS, the determinants of policy cost-effectiveness at sector level are addressed. Firstly, intensity levels for the FARMIS activities are defined in order to model uptake of agri-environmental policies with FARMIS, secondly, life-cycle assessment data is attached to these intensity levels to determine environmental effects of the policies and thirdly, public expenditure is calculated under consideration of transaction costs. This paper concludes delineating the strengths and limitations of the approach
Effects of street traffic noise in the night
The relationship between automobile traffic noise and the degree of disturbance experience experienced at night was explored through a random sample survey of 1600 individuals in rural and urban areas. The data obtained were used to establish threshold values
Asymmetric Magnetosphere Deformation Driven by Hot Flow Anomaly(ies)
We present a case study of a large deformation of the magnetopause on November 26, 2008. The investigation is based on observations of five THEMIS spacecraft located at the dawn flank in the magnetosphere and magnetosheath, on Cluster measurements at the dusk magnetosheath, and is supported by ACE solar wind monitoring. The main revelation of our study is that the interaction of the IMF discontinuity with the bow shock creates either one very elongated hot flow anomaly (HFA) or a pair of them that is (are) simultaneously observed at both flanks. Whereas the dusk HFA is weak and does not cause observable deformation of the magnetopause, the pressure variations connected with the dawn HFA lead to a magnetopause displacement by approx. = 5 R(sub E) outward from its nominal position. This is followed by a rapid inward motion of the magnetopause approx. = 4 R(sub E) inward with respect to the model location. The surface deformation is so large that the outermost THEMIS spacecraft was in the magnetosphere, whereas the spacecraft located 9 R(sub E) inbound entered into the magnetosheath at the same time. The whole event lasted about 5 minutes
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