Industrial impact of noise control

New emphasis on noise control will have widespread industrial impact. Increased allocations of time and money will have to be made in research and development (added targets for given products to meet, needed new products), manufacturing (additional increments upon manufactured items and additional controls upon the process itself), distribution, warranties, and advertising. Specific examples are cited: (1) one of the most intractable aspects of the highway noise problem is tire noise, which increases with speed and loading if presently known design practices are followed; some present research leads are discussed, (2) vacuum cleaners can be made much quieter with relatively low added cost; however, quiet vacuum cleaners have not sold in the past since the public feels the noise is a sign of adequate cleaning capacity, which presents an advertising challenge, (3) present lumber cutting techniques cannot be performed without high noise levels; suitable alternatives are not apparent and a very fragmented industry finds necessary research and development costs hard to fund.     

Techniques of noise abatement: control at the receiver

To protect the receivers, the human ears, from exposure to excessive noise the complete range of mechanical anti-noise ear protectors is outlined. The ear plugs, semi-inserts, ear muffs, and helmets are explained with respect to basic desirable features of an ideal ear protector. These ear protectors are ranked and compared. Finally, effective use of ear protectors is described.     

The role of environmental groups in the control of noise

Much environmental protection and restoration activity has resulted directly from the efforts of citizen environmental groups. This paper describes significant contributions of such groups to the control of noise pollution and examines the techniques used to achieve the desired results. Some of the problems faced by noise control groups are discussed, and the prevailing climate for their present and future activities is assessed.     

Acute and genetic toxicity of municipal landfill leachate

The large number of municipal solid waste (MSW) landfills and the many hazardous materials which they contain pose a serious environmental threat to our groundwater reserves. The present study was conducted to assess the environmental hazards that four MSW landfill leachates pose to the groundwater. Genetic toxicities of the landfill leachate and groundwater samples were assessed using the Salmonella/microsome (Ames test) mutagenicity bioassay, the Bacillus subtilis DNA repair bioassay, and the diploid Aspergillus nidulans chromosome damage bioassay. Acute toxicities of the leachate samples were assessed using the Microtox test. The leachate and groundwater samples were also analyzed for organic constituents using gas chromatography and gas chromatography/mass spectrometry. The chemical data were used to calculate the estimated cumulative cancer risk for each sample. All leachate samples were acutely toxic, and three of the four leachate samples were genetically toxic. Two of the four leachate samples and the groundwater sample contained concentrations of USEPA priority pollutants in excess of promulgated standards for potable water. Two of the leachates had mean estimated cumulative cancer risks on the same order of magnitude (10^?4) as leachates from co-disposal and hazardous waste landfills. The use of a battery of acute and genetic toxicity bioassays, chemical analysis, and an estimated cancer risk calculation resulted in evidence that MSW landfill leachates are as acutely and chronically toxic as co-disposal and hazardous waste landfill leachates.     

Utilization of nutrients from animal manure: legislation and technology solutions

Journal of Soils and Sediments -     

Vehicle noise enforcement

On January 1, 1968, California entered the field of enforcing motor vehicle noise limits by the use of sound level meters. The program is still growing, procedures are being developed and modified, and new directions are anticipated. This overview describes the current vehicle noise measurement operation, the background that led up to the present laws, problems that have arisen, and plans for the future.     

Mercury pathways in municipal wastewater treatment plants

A nine-week sampling and analysis program was completed at a large municipal wastewater treatment plant to characterize the fate of Hg entering the plant. Mercury removal in primary treatment averaged 79%, and the average Hg removal across the entire plant was approximately 96%. Mercury loadings on the secondary (activated sludge) treatment process were elevated to near plant influent levels due to the recycle of spent scrubber water from sewage sludge incinerator emissions control equipment. This internal recycle of spent incinerator scrubber water resulted in elevated Hg loadings to the incinerators, and effectively reduced the Hg control efficiency of the emissions control equipment to near zero. Measurements indicate that approximately 95% of the Hg mass entering the plant is discharged to the atmosphere via sludge incinerator emissions. These results indicate that municipal wastewater treatment facilities can remove Hg from wastewater quite effectively; however, where wastewater sludge is incinerated, almost the entire mass of Hg removed from the wastewater can be discharged to the atmosphere.     

地市级公共图书馆的虚拟参考服务

虚拟参考服务代表了参考咨询服务发展的方向,也是目前图书馆界的大热点,它借助因特网的普及和完善在全球迅猛发展。本文详细论述了开展虚拟参考服务的意义、地市级公共图书馆开展虚拟参考服务的现状及地市级公共图书馆开展虚拟参考服务的条件和方式等。     

Treated municipal wastewater for citrus irrigation 1

Treated, reclaimed municipal wastewater was evaluated on citrus trees in central Florida for over six years. The effects of irrigation with reclaimed wastewater on soil water content, soil chemical analysis, leaf mineral status, and fruit quality were compared with those of irrigation with well water. Irrigation with reclaimed water increased mineral residues in the soil profile, altered leaf mineral concentration and fruit quality, and promoted better tree performance and more weed growth relative to irrigation with well water. Higher accumulation of nitrogen (N), potassium (K), calcium (Ca), and magnesium (Mg) in soils irrigated with reclaimed water were not significantly reflected in leaf mineral status. Although leaf sodium (Na), chloride (Cl), and boron (B) concentrations were noticeably higher in reclaimed water treatments than in those of well water, they are still far below the toxicity levels. This highly treated wastewater in central Florida has been found to be a very safe and good option for increasing water supplies, but not a significant source of plant nutrients to citrus trees.     

城市生活垃圾堆肥过程中腐熟度指标及控制参数

以日处理400 t经马家楼筛分处理后的15～60 mm生活垃圾的北京南宫堆肥厂垃圾堆肥过程为研究对象,对堆肥过程中垃圾的理化性质、腐熟度指标与控制参数进行了研究。结果表明,堆肥过程中水分含量是下降的;不同季节堆肥pH值的总体变化均呈上升趋势;电导率(EC)降到了作物受抑制的限定值以下,不会对作物产生盐分毒害;堆肥水浸提的腐殖酸E₄/E₆值随着垃圾堆肥腐熟度升高呈增加趋势;24 h和96 h的发芽率指数(GI)表明垃圾堆肥时间可以从8周缩短到5周;有机碳、总氮和C/N比随着堆肥时间的增加均呈下降趋势;C/N比与E₄/E₆值和GI(24 h和96 h)值呈显著负相关关系,EC值与E₄/E₆值和GI(24 h和96 h)值呈极显著负相关,而E₄/E₆值与GI(24 h和96 h)值呈极显著正相关。     

Highway noise abatement techniques

The ability of alternate highway designs, landscaping procedures, berms, and sound barriers to reduce the noise intrusion from highway traffic will be discussed. The effects of meteorology on the propagation of sound relative to these abatement techniques will also be presented. Traffic controls on speed and acceleration determine the noise emission levels from the traffic. The potential of these controls to reduce noise levels in the community is described.     

固体物理中的态函数

1900年Plank提出了物理学第一定律黑体辐射理论,Plank的BlackBody辐射可以扩大到整个微观世界,所有微观世界都符合Plank的BlackBody辐射。固体物理以及固态物理是由固态的波函数以及能带波函数构成的。固态中的波函数是布洛赫态函数,固体物理中的态函数是研究各种各样运动的可能性,各种各样的运动的可能性构成了物质的态函数。     

The nature of noise

Noise, defined as sound undesired by the listeners, has long been regarded as the tribute we pay for progress. No longer is this true, for the engineering tools with which effectively to combat noise already exist. Developing and applying reasonable and acceptable legal and economic pressures has forced increasing use of these tools. In this Symposium there will be detailed discussions on these operational aspects of noise control. Here we concentrate on measurement aspects. The history of noise control engineering can be written in terms of efforts to find objective physical measures that show acceptable correlation with psychological or physiological responses to the noise stimulus. Such measures must take account of the three chief dimensions of noise, which (with their subjective counterparts) are intensity (loudness), frequency (pitch), and waveform or spectrum (quality or timbre). In discussing the interrelations we are led to the importance of the decibel system, and to consideration of ear response characteristics and schemes for getting a single number rating for noise. But because the effects of noise include such disparate ones as distraction, annoyance, speech interference, possible systemic physiological trauma, and hearing loss, it is difficult to conceive of any single measure being satisfactory. Nevertheless, in the A-weighted sound level we have a likely candidate. This measure will be discussed in detail, with examples of measurement situations including aircraft, ground transport, and industrial noise. Techniques for obtaining valid data will be emphasized. A few unsolved problems will be noted, including uncertain physiological effects, evaluation of impulse noise, and economical sampling of community noise.