大型综合医院室外声景观评价影响因素分析——以长沙市中心医院为例

大型综合医院室外本是医患康复疗养、舒缓身心的场所,但并未引起足够的重视,噪声影响严重,声景观较差.该文以长沙市中心医院为例,通过定点实测结合问卷调查的方式,探究影响大型综合医院室外声景观评价结果的因素.结果表明:长沙市中心医院室外声景观整体满意度一般,语义词调查结果整体偏向贬义负值,受访者身份、调查时间和声源构成对声景...     

大学物理成绩影响因素的量化研究——以中国农业大学为例

为激发学生学习的积极性,过程性评价及考核在大学物理课程的学习中具有重要的地位.以中国农业大学水产专业学生为例,针对不同过程性评价方法对课程成绩的影响进行量化研究,分析了4个影响因子(阶段测试、出勤率、章节总结、平时作业)与课程期末成绩的相关性.研究结果表明：4种影响因子与期末成绩并不是全部高度相关(超过95%置信度).平时测试成绩与期末成绩相关度最高,作业成绩和出勤率与期末成绩的相关性次之,章节总结与期末成绩的相关性不显著.     

城市社区公园声景分布与景观特征关联性研究——以沈阳鲁迅公园为例*

城市社区公园为附近居民提供休憩与交往的公共空间,使用者是公园声景的创造者也是体验者。在公园设计中,将建成后的声景纳入考虑因素,在支持居民休闲活动的同时,创造良好的听觉环境体验,具有提升人居健康福祉和空间公平的现实意义。该研究以城市社区公园——沈阳鲁迅公园为研究对象,通过现场声景调查和使用者问卷,探究声景时空分布特征及居民体验;建构公园景观特征指数,探讨声景时空分布与景观特征的关联性。数据表明：自然声、居民活动声和周围道路交通声构成公园丰富的声景要素,园区内声压级、各类声事件感知显著性呈现不同的时空分布特征;受访者对典型声事件的愉悦性和干扰性评价呈现聚类性特征;以此为基础构建的表征公园景观特征的自然指数、人群聚集指数和交通影响指数,其分别与对应声事件的感知显著性显著相关。基于景观特征与声景分布的关联性,结合公园使用者的声景体验,提出与公园景观设计相结合的社区公园声景优化策略。     

基于GIS的高密度城市声景质量及其影响因素研究——以广州天河区为例

高密度城市空间背景下,声景质量对居民生活品质及身心健康具有显著影响.已有声景研究针对街区尺度的声景质量及其形成机制的探讨仍较为不足,尚未能为高质量宜居城市空间建设提供循证基础.该文基于地理学视角,通过声景漫步与问卷调查对广州市天河区南部声源类型、声环境特征、心理声学感知进行调查研究,旨在阐述城市街区尺度声景质量的空间特...     

A comparative study on the modeling of sound pressure field distributions in a sonoreactor with experimental investigation

In sonochemical reactors the effect of emerging cavitation bubbles has significant influence on the amplitude and structure of the developing sound field. Calculations show that the damping parameter and the phase velocity may, depending on the pressure amplitude, change by several orders of magnitude. For example, the sound velocity in water comes to 1500 ms⁻¹, whereas in a bubbly liquid it may decrease to 20 ms⁻¹, which is much below the velocity of sound in air (about 340 ms⁻¹). In this paper, a method of calculating the time dependent three-dimensional pressure field in sonochemical reactors of various shapes is presented. It takes into account inhomogeneous distributed wave parameters which are a function of the spatial depending pressure amplitude. The modeled results are then compared with experimentally measured values of a certain kind of reaction vessel. The agreement is found to be satisfactory.     

A study of indoor radon levels in Indian dwellings,influencing factors and lung cancer risks

Passive integrating solid state nuclear track detectors (SSNTDs) were used to study the Radon-222 (Rn) concentrations in Indian dwellings. The study was made in 300 dwellings in the cities of Lucknow and Kanpur in northern India. The influence of some factors e.g. age of the house, number of floors and ventilation conditions, etc. on indoor Rn concentrations were studied. The equilibrium factor in 65 dwellings were also investigated. Average Rn concentrations in living rooms were found to be 34±8 Bq.m⁻³ and 40±10 Bq.m⁻³ respectively, with equilibrium factors of 0.35 and 0.38. Assuming an occupancy factor of 0.8, the annual average effective dose equivalents in living rooms of the two places are estimated as 0.8 and 1.0 mSv respectively.The average life-time risks of lung cancer for radon exposure of the Lucknow and Kanpur populations at home would be about 0.26% and 0.34% respectively and the mean relative loss of life expectancies were 0.06% and 0.074% respectively.     

The main factors influencing the O vacancy formation on the Ir doped ceria surface: A DFT+U study

The effects of Ir doping on the oxygen vacancy formation energy have been investigated using the DFT+U method, i.e., first-principles density functional theory calculations with the inclusion of the on-site Coulomb interaction. The main factors influencing the reducibility of Ir-doped ceria are studied carefully. It is found that, although the Ir doping induces gap states (MIGS) as do other noble metals (Pd, Pt, Rh), the structural relaxation (instead of the electronic structure relaxation) is the main factor responsible for the decrease of the oxygen vacancy formation energy, i.e., the Ir doping makes structural distortions much more exothermic for the reduced ceria.     

A basic study on the sound field analysis of periodic structures by boundary integral equation method

This study deals with the development of the approximate method to analyze the sound field around equally spaced finite obstacles, using the periodic boundary condition. First, on the assumption that the equally spaced finite obstacles are the periodically arranged obstacles, the sound field is analyzed by boundary integral equation method with a Green’s function which satisfies the periodic boundary condition. Furthermore, by comparing these results and the exact solution by using the fundamental solution as Green’s function, the validity of the approximate method is also investigated. Next, in order to evaluate the applicability of the approximate method, the simple formula using some parameters, i.e., the frequency, the period, and the number of obstacles, etc., is proposed. The results of the sound field analysis applied the formula are presented.     

Dependence of magnetic field generation by thermal convection on the rotation rate: A case study

Dependence of magnetic field generation on the rotation rate is explored by direct numerical simulation of magnetohydrodynamic convective attractors in a plane layer of conducting fluid with square periodicity cells for the Taylor number varied from zero to 2000, for which the convective fluid motion halts (other parameters of the system are fixed). We observe 5 types of hydrodynamic (amagnetic) attractors: two families of two-dimensional (i.e. depending on two spatial variables) rolls parallel to sides of periodicity boxes of different widths and parallel to the diagonal, travelling waves and three-dimensional “wavy” rolls. All types of attractors, except for one family of rolls, are capable of kinematic magnetic field generation. We have found 21 distinct nonlinear convective MHD attractors (13 steady states and 8 periodic regimes) and identified bifurcations in which they emerge. In addition, we have observed a family of periodic, two-frequency quasiperiodic and chaotic regimes, as well as an incomplete Feigenbaum period doubling sequence of bifurcations of a torus followed by a chaotic regime and subsequently by a torus with 1/3 of the cascade frequency. The system is highly symmetric. We have found two novel global bifurcations reminiscent of the SNIC bifurcation, which are only possible in the presence of symmetries. The universally accepted paradigm, whereby an increase of the rotation rate below a certain level is beneficial for magnetic field generation, while a further increase inhibits it (and halts the motion of fluid on continuing the increase), remains unaltered, but we demonstrate that this “large-scale” picture lacks many significant details.     

Effects of urban morphology on the traffic noise distribution through noise mapping: A comparative study between UK and China

Due to the rapid urban development and massive population increase in many eastern cities, the difference in urban density and morphology between typical western and eastern cities is becoming significant. This consequently makes the noise distribution in the eastern cities rather different from typical low density European cities. In this research, two representative cities with different urban densities, Greater Manchester in the UK and Wuhan in China, were selected, which have low and high average urban density respectively, and also have considerable differences in building form and traffic pattern. In the mean time, these two cities have similar urban scale and traffic amount. In each city, based on the urban morphological analyses considering urban land-use, building and road density, and noise source distribution, a number of typical urban areas, 500 * 500 m² each, were sampled. A noise-mapping software package was then used to generate generic noise maps, based on existing digital vector maps for terrain and building, and traffic data obtained by on-site measurements. The comparison results show that the average and minimum noise level in Greater Manchester samples is generally higher than that in Wuhan samples, while the maximum noise level in Wuhan samples is mostly higher. By developing a Matlab program, correlations have been analysed between noise distributions and the urban characteristics relating to urban density, such as the road and building coverage ratio. Overall, comparisons between these two typical cities have shown significant effects of urban morphology on the traffic noise distribution.     

Determining an influencing area affecting walking speed on footpath: A case study of a footpath in CBD Bangkok,Thailand

Intuitively, the crowd density in front of a pedestrian will affect his walking speed along a footpath. Nevertheless, the size of the influencing area affecting walking speed has rarely been scrutinized in the past. This study attempts to determine the distance in front of pedestrians that principally affects their walking speed under normal conditions, using a case study of a footpath in Bangkok. We recorded pedestrian activities along a test section of 20 m, with an effective walking width of 2.45 m in the morning and at noon. The morning dataset was extracted for analyzing various influencing distances, ranging from 1 to 20 m in front of the pedestrian. The bi-directional walking speed–pedestrian density models were developed, for each tested distance, using linear regression analysis. It was found that an influencing length in the range of 5–8 m yields the highest correlation coefficients. In the case of high density conditions, the walking speed of the equally-split flow (50:50) was found to be higher than other proportional flow analyzed. The finding has useful implications on the improvement of the walking simulations in mesoscopic models.