湿地公园声环境效应

随着旅游业发展,对环境影响日益凸现。笔者以无锡市蠡湖公园为例研究城市公园旅游环境效应。从旅游活动与环境间的关系,旅游建设和环境间的关系,环境对游客的影响3个方面着手,研究旅游环境效应。研究结果表明,游客量(N)与旅游噪声源(Leq,dB)之间的关系是Leq=19.91 7.08191nN。声波在传播过程中因园林植物的吸收、反射等作用损失了4.3dB,蠡湖公园内植物宽度、密度、高度、种类组成以及林带结构方面在噪声削减方面未完全发挥作用。大多数游客对蠡湖公园的声环境表示满意。     

Sound absorption property of wood for five eucalypt species

The sound absorption coefficients of wood and wood boards for five eucalypt species (Eucalyptus urophylla, Eucalyptus urophylla x E. grandis, Eucalyptus urophylla x E. tereticornis, Eucalyptus urophylla x E. camaldulensis and Eucalyptus cloeziana) that were collected from plantation in Dongmen Forestry Center of Guangxi Province, China were tested with standing wave method and their sound absorption properties were also compared. The results showed that the sound absorption coefficients of the five eucalypt wood species did not change evidently below 1000 Hz, but above 1000 Hz their sound absorption coefficients increased with the increasing frequency. The difference in sound absorption coefficient among five species of eucalypt wood is not evident at the tested frequency range (200–2000 Hz), but the sound absorption property ofEucalyptus urophylla at low frequency is better than that of other four species. The sound absorption coefficient of the tangential-sawn board is higher than that of the radial-sawn board. The sound absorption property of eucalypt wood of 0.5 cm in thickness is much better than that of 1.0 cm in thickness. It is concluded that wood sound absorption properties of eucalypts are affected by their board thickness and the type of sawn timber within the testing frequency, but the variance of wood sound absorption property among the five tested species is not significant. Fundation item This study is Part of 2000-4-13 in “948” Project from the State Forestry Administration of P.R. China Biography: JIANG Ze-hui (1939-), female, Professor in Research Institute of Wood Industry in Chinese Academy of Forestry. Responsible editor: Chai Ruihai     

Real-time analysis of chicken embryo sounds to monitor different incubation stages

The objective of this paper is to develop an algorithm that could be used in order to reduce the spread of chicken hatching in industrial incubators for chicken eggs. The approach that is used is based on frequency analysis of sounds recorded inside the industrial incubator and aims at identifying the time at which all the eggs inside the incubator have reached the internal pipping stage. The developed algorithm is able to be calibrated automatically in order to adjust for sounds around the incubator and the acoustics of every incubator. The algorithm has been implemented in a Digital Signal Processor and applied in real-time in an industrial environment. It is shown that the algorithm can correctly identify the time at which 93-98% of the eggs have had been in the internal pipping stage. This level of accuracy is considered adequate for a practical application focusing on reduction of the hatching window.     

试论"人的价值追求是人全面发展的动力"

人的价值追求作为一种为实现自身价值最大化的理想追求,是主体本质力量的重要表现,是人全面发展的内在动力,对自身价值理想的实现具有极大的激励作用.马克思认为,人的全面发展是终极目标和渐进性过程的统一.     

双传声器声强测量系统误差分析与不确定度评定

双传声器互谱声强测量法适用于现场测量机器的声功率和进行声源识别。为了提高测量精度，需要分析影响测量精度的各种因素，确定被测量值的估计值和分散性。从双传声器互谱法测量声强的原理及测量系统的配置出发，分析讨论了互谱声强测量中误差产生的原因及其影响声强测量精度的主要因素；对声强测量系统测量声强量值的不确定度进行了评估，并对评定结果进行了实验验证，评定结果与实际检测结果相符；同时给出了减小声强测量系统主要误差的可能途径。     

Marine bird response to forage fish during winter in subarctic bays

Despite the importance of understanding marine bird response to prey fish, few studies have examined this relationship during winter. Over a 5‐year period, we conducted synoptic marine bird and hydroacoustic forage fish surveys during early (November) and late (March) winter to characterize the factors influencing marine bird and forage fish dynamics at two spatial scales (fish school and bay) within subarctic bays of coastal Alaska, USA. Over 40% of observed marine birds were associated with a fish school (within 150 m of a fish school), although only 20% of fish schools were associated with birds. Seasonally, we recorded significantly more schools during early winter. The marine bird community also shifted from being comprised primarily of marbled murrelets (Brachyramphus marmoratus) and large gulls (Larus spp.) in early winter to common murres (Uria aalge) in late winter. At the school level, marine birds were more likely to be associated with shallow fish schools within 500 m of shore and in smaller prey patches. At the bay level, gull abundance was positively associated with the total number of fish schools recorded, while diving birds were more abundant when fish schools were higher in the water column, in shallower bottom depths, and in areas with more eel grass habitat. Our results indicate the importance of temporal, habitat, and fish school variables as drivers of marine bird presence and abundance, underscoring the complexity of predator–prey dynamics in the marine environment during winter.     

A feasibility study for the application of climate change vulnerability assessments on species in the Tallurutiup Imanga National Marine Conservation Area

相似文献   

声强测量中相位失配误差及校正方法

在声强测量技术中,相位的配是引起测量误差的主要因素,通过计算和分析,找出引起相位失效的原因,并提出了在ＦＦＴ测量中,对系统相位失配误差进行校正的方法。     

Manufacture and properties of ultra-low-density fiberboard

Low-density fiberboards with densities ranging from 0.05 to 0.50g/cm³ were manufactured with steam injection pressing. Bond-type and foam-type isocyanate compound resin adhesives were used separately at 10% and 30% resin content levels. Two types of different-size fibers from softwood were used. Mechanical, dimensional, thermal, and sound insulation properties of the fiberboards were tested. The results are as follows: (1) Bond-type isocyanate adhesive showed higher mechanical and dimensional properties of low-density fiberboards than the foam-type adhesive. (2) Fiberboards produced from small fibers have better mechanical and dimensional properties than those made from large fibers. (3) Thermal conductivity of fiberboards depends more on the board density than on the type of resin or fiber dimension. At a board density lower than 0.2 g/cm³, the thermal conductivity is almost equivalent to those of thermal insulation materials such as polystyrene foam and rock wool, (4) Generally, the sound absorption coefficient of low-density fiberboards tends to increase at higher sound frequency. As the board thickness increases, low-frequency sounds are more readily absorbed by boards.Part of this report was presented at the 46th annual meeting of the Japan Wood Research Society, Kumamoto, April 1996     

用声强法对木工带锯机空转噪声特性的测量分析

使用声强法对木工带锯机的噪声特性进行了测量,测得三面的声强值和噪声的矢量图、等高线图、三维图,由这些数据和线图可以全面了解带锯机的噪声分布情况,以便分析和控制噪声。