车用发动机噪声源识别方法的研究

利用声强测试中的p-p法,对一台汽油机的噪声进行声强测试,将测试得到的数据用STARAcoustics声强分析软件进行处理和分析,得出发动机各个包络面的等声强分布、声强矢量分布、声功率和声功率级的计算结果;利用这些结果分析和识别了该发动机几个包络面的主要噪声源,确定了其噪声源的位置、主要噪声频率、声功率的大小及声功率的贡献,为降低该发动机噪声提供了改进依据。     

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。     

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.     

Growth and spawning of hatchery-reared Chinese white prawn Penaeus (Fenneropenaeus) chinensis released in the Ariake Sea, Japan

SUMMARY: Growth and reproduction of hatchery-reared Chinese white prawn Penaeus chinensis released in the Ariake Sea, Japan, were examined. Chinese white prawn grew rapidly, reaching a body length of 154 mm in males and 198 mm in females by November (219–229 days after hatching). Maximum body length of sampled individuals was 164 mm in males and 223 mm in females. Growth curve of the Chinese white prawn was fitted to the Pitcher and MacDonald's formula, L_t = 155.0{1 − e ^{2.925sin[2π(t − 16.151)/365] − 0.0623( t − 10.712)}} for males and the logistic curve, L_t = 200.3/[1 + e ^{(1.985–0.034 t )}] for females (where L_t is the body length t days after release and t is the number of days after release). Females reached sexual maturity in late February and spawning occurred until April. Minimum size at ripe and spawned stages was 189 mm and 193 mm body length, respectively.     

万家沟水库坝基(肩)固结灌浆的实施与分析

万家沟水库砼双曲拱坝为自治区第一座此类坝型。对坝基（肩） 要求甚高，其整体性与强度的提高对大坝的稳定性至关重要。而欲达此目的，固结灌浆是重要手段。万家沟水库坝基（肩） 固结灌浆后，通过常规手段的测试表明，其整体性与强度已得到明显改善。     

Distribution and population genetic structure of river- and sea-type sockeye salmon in western North America

Abstract– In contrast to the well-known "lake-type" sockeye salmon, two additional anadromous life-history types have been recognized within the species: 'river-type' sockeye salmon whose juveniles spend 1 or 2 years in off-channel river habitats prior to migrating to sea, and "sea-type" sockeye salmon that initially rear in similar river habitats yet migrate to sea as underyearlings. Persistent populations of river-/sea-type sockeye salmon occur in small numbers throughout the species'range in North America but are usually associated with glacier-fed rivers. We found published and unpublished records showing that riverine-spawning sockeye salmon occur in 11 rivers in western Washington, USA, that don't have access to juvenile lake-rearing habitat. Evidence of persistent spawning was strongest for the Nooksack and Skagit rivers in northern Puget Sound. We analyzed allozyme frequency differentiation in 26 laketype and 12 river-/sea-type populations of sockeye salmon in North America, ranging from northern Puget Sound, Washington (including 3 in the Nooksack and Skagit rivers) to northern Southeast Alaska. Across this 2000 km range, river-/sea-type sockeye salmon showed very little genetic differentiation between populations, much less than that displayed by the highly divergent lake-type sockeye salmon. Genetic similarity among river-/sea-type sockeye salmon in this study is likely a result of common ancestry and a high level of historical gene flow among river-/sea-type sockeye salmon populations.     

基于LabVIEW的声强测量分析系统的研究

本文从硬件、软件两部分分别介绍了基于LabVIEW的声强测量分析系统的设计与开发.硬件部分主要介绍了信号调理模块中放大器的设计与实现.软件部分阐述了声压级、1/3倍频程声压级谱、声强级谱等各功能模块实现的原理和程序开发,该系统实现了声强的测量与分析.