Motorway noise modelling based on perpendicular propagation analysis of traffic noise

A model for motorway traffic noise has been obtained from measurements along the the Bangkok-Chonburi motorway. The model’s parameters include traffic volume and combination, the average spot speed of each type of vehicle and the physical conditions of the motorway in terms of right-of-way width, number of lanes, lane width, shoulder width, and median width for both of the main carriageways and frontage roads. The noise level that is generated by each type of vehicle has been analyzed according to the propagation in the direction perpendicular to the center line of motorway’s carriageway. The total traffic noise is then analyzed from traffic volume of all vehicle types on both sides of carriageways and frontage roads. The basic noise levels used in the motorway traffic noise model are modified according to the effective ground effect along the propagation path. The final result of this study is that a motorway traffic noise model based on the perpendicular propagation analysis technique performs well in a statistical goodness-of-fit test against the field data, and therefore, can be used effectively in traffic noise prediction for related or similar motorway projects.     

Performance of a motorway noise barrier at Heston

This paper reports on the performance and costs of a 300 m long experimental noise barrier erected alongside an elevated section of the M4 motorway to protect existing two-storey housing which is as close as 20 m to the motorway. Measured reductions in L₁₀ values, at the façades of these dwellings, were around 8 dB(A) at first floor windows and around 4 dB(A) at ground floor windows. These measured reductions were based on the levels with no barrier but with some screening due to the elevation of the road.A wooden fence in the barrier position at the start of the experiment gave reductions of about 3 dB(A) at the façades of the nearby houses. The subjective impressions of the occupants showed a markedly favourable overall reaction to the change from the wooden fence to the experimental noise barrier.A reduction in the variability of the received noise levels from the partially screened situation without a barrier to the screened situation was found. There was no significant increase in noise levels for positions on the opposite side of the motorway.     

Generalized canonical osp(1,2) quantization

A possibility of constructing a generalized canonical quantization for arbitrary dynamical systems with first-class constrains is considered based on the invariance principle of the osp(1,2) global supersymmetry. Tomsk State Pedagogical University, Russia; Departamento de Fisica, ICE, Universidade Federal de Juize de Fora, Brazil. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 3–6, October, 1999.     

开放光程扬尘颗粒物浓度测量方法及系统

利用单波长激光通过扬尘空间发生散射消光衰减的特性,设计了开放光程的颗粒物浓度检测方法及系统。该方法利用双峰正态分布模型模拟颗粒物粒径分布,实时计算一定空间范围内的扬尘颗粒物浓度,具有响应速度快、测量动态范围宽的优点,适合浓度高、变化快、空间范围大的扬尘颗粒物浓度测量。通过水溶胶模拟实验与烟尘实验验证了该方法的可行性。实验数据表明,系统量程可达0~400mg/m3,分辨率为0.05mg/m3,响应时间小于1s。     

Time dependence characterization of Pb and Br concentrations in samples from ombrotrophic peat bogs in Austria and Poland by energy‐dispersive x‐ray fluorescence spectrometry

It long has been known that ombrotrophic peat bog preserves the record of the atmospheric deposition of metal pollutants. In this paper, the results of an investigation of two peat cores taken in Austria from Langmoos bog located near a motorway and one taken in southern Poland located far away from main roads are presented. The concentration levels of Pb and Br in dated peat cores were studied in order to find out whether the close location of a motorway to a bog will influence the contents of these elements in peat. Copyright © 2002 John Wiley & Sons, Ltd.     

Ground effect and motorway noise

Recent research into the unobstructed propagation of motorway noise has provided further information on ground absorption. This Note takes this information into account in making new proposals for the effect of the ground on the prediction of noise from motorways.     

3D analysis and investigation of traffic noise impact from a new motorway on building and surrounding area

This study analyzes and investigates the impact of traffic noise on the high-rise building and surrounding area by the side of a new motorway that links Bangkok to the new Suwannaphum International Airport and Pattaya. A traffic noise simulation model in 3D form is applied on a GIS system. Visualized noise levels are formulated in vectored contours for noise mapping on all surfaces of the building and surrounding ground in a 3D platform. Noise impact is then investigated based on this 3D noise mapping in LAeq,1 h noise contours. The investigation shows that there is a high traffic noise impact on the foreground and front façade of the building, rendering this area unsuitable for residential purposes. The ground area by the sides of the building and the building side panels receive a lower noise impact. Most of these areas are still not acceptable for residential use; however, all of the side panels and most of the ground area by the sides of the building can be used for commercial and business purposes. The back yard and back panel, together with the rooftop, have the lowest traffic noise impact. They are the safest places for use as residential areas, except for a small strip along the front edge of the rooftop. From this study, residential areas that are sensitive to noise impact must be located far away from the front façade and side panels of a building. It is also shows that the building height is not an effective means of reducing motorway noise on the upper part of the building.     

Low-energy excitations of Yb As in a magnetic field

We discuss the effects of an applied magnetic field on the low-energy excitations in the low temperature phase of Yb₄As₃. We show also why the magnetic interaction of the Yb³⁺ ions is nearly of an isotropic Heisenberg spin-1/2 type. A small anisotropy due to an intrachain dipolar interaction leads to the opening of a gap when a magnetic field is applied. The model agrees with available experimental data. Simple experiments are suggested in order to further test the present theory. Received 3 February 1999     

Experiments on the GIT-4 with the load connected upstream of the plasma opening switch

Experiments have been performed on the GIT-4 generator with a plasma opening switch to study the operation of a circuit connecting the load and the switch through an untriggered spark gap depending for its operation on a discharge over the surface of a dielectric in vacuum. The current switching into inductive loads of different inductance was investigated. The dependence of the time the switch is open on load inductance has been found. It has been demonstrated that the surface-discharge spark gap can be used at current rise rates of up to ∼2·10¹³ A/s. Institute of High Current Electronics, Siberian Branch of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 31–35, December, 1999.     

变频空调制冷系统流量调节性能分析和实验研究

通过实验分析不同膨胀阀开度和压缩机频率下系统性能。过热度在‘0’点及前后情况下,制冷系统性能及回油状况随膨胀阀开度调节,会出现较大变化。且在过热度为‘0’时系统制冷量和能效比最高。同时对不同频率下系统性能参数变化规律尤其是换热器效率影响进行分析。给出膨胀阀开度和压缩机变转速联合调节在系统性能最优状态下调节策略。