关于玉立吸排油烟机的振动控制和降噪研究

本文对吸排油烟机进行测试,得到了振动和噪声的频率谱和相干函数,弄清了振动源和噪声源,在理论指导下应用高阻尼技术和消声方法降低了油烟机的噪声,提高了产品的档次。     

遥感在滑坡调查中的应用

本文介绍了遥感技术在滑坡的现状调查和防治中的应用.提出了航天、航空遥感图像上滑坡现状、规模、易滑地点、稳定性评价等的直接和间接判读标志;并展望了遥感技术在滑坡动态监测中的应用前景.     

铝箔酸洗废液中盐酸的回收和利用

用于制造电容器的铝箔用混酸（盐酸与少量硫酸混合）进行酸洗处理,处理后所剩废液中含有大量的盐酸、少量ＳＯ２－４和Ａｌ３＋,总酸度（以ＨＣｌ计）约５ｍｏｌ／Ｌ。一家中型电子元件厂日产这种废液８ｔ多,现全国同类工厂有３０余家。目前,只有少量废酸液用于配制锅...     

了解过去是通向未来的方舟

<正> 前言70年代一个重要的地质研究领域问世了。这个领域和许多新的科学领域一样是根据实际需要而创立的。这个领域随着环境问题而逐渐发展起来,因此,它继承了多年的传统,包括中世纪晚期的天文学和第二次世界大战以后兴起的粒子或空间物理学这样一些领域。一般从地质学的角度来说,我们总是尽量想了解地球的过去,而且常常利用均变说定律,即现在是了解过去的钥匙。这个新领域利用现在和过去来预测未来的地质发展趋势或各种地质事件。地质预测涉及到三个主要的课题:     

高效藻类塘在污水处理中的研究及应用前景

高效藻类塘是在传统稳定塘的基础上发展起来的极具推广价值的污水处理技术。它具有停留时间短,水深浅,对氮磷的去除效果好的特点。本文阐述了高效藻类塘的特点、影响因素及去除机理,并展望了其应用前景。     

Nitrogen removal and nitrate leaching for two perennial,sod-based forage systems receiving dairy effluent

In northern Florida, year-round forage systems are used in dairy effluent sprayfields to reduce nitrate leaching. Our purpose was to quantify forage N removal and monitor nitrate N (NO3(-)-N) concentration below the rooting zone for two perennial, sod-based, triple-cropping systems over four 12-mo cycles (1996-2000). The soil is an excessively drained Kershaw sand (thermic, uncoated Typic Quartzip-samment). Effluent N rates were 500, 690, and 910 kg ha(-1) per cycle. Differences in N removal between a corn (Zea mays L.)-bermudagrass (Cynodon spp.)-rye (Secale cereale L.) system (CBR) and corn-perennial peanut (Arachis glabrata Benth.)-rye system (CPR) were primarily related to the performance of the perennial forages. Nitrogen removal of corn (125-170 kg ha(-1)) and rye (62-90 kg ha(-1)) was relatively stable between systems and among cycles. The greatest N removal was measured for CBR in the first cycle (408 kg ha(-1)), with the bermudagrass removing an average of 191 kg N ha(-1). In later cycles, N removal for bermudagrass declined because dry matter (DM) yield declined. Yield and N removal of perennial peanut increased over the four cycles. Nitrate N concentrations below the rooting zone were lower for CBR than CPR in the first two cycles, but differences were inconsistent in the latter two. The CBR system maintained low NO3(-)-N leaching in the first cycle when the bermudagrass was the most productive; however, it was not a sustainable system for long-term prevention of NO3(-)-N leaching due to declining bermudagrass yield in subsequent cycles. For CPR, effluent N rates > or = 500 kg ha(-1) yr(-1) have the potential to negatively affect ground water quality.     

景观生态学在建设项目生态环境影响评价中的应用

景观生态学目前是国家环境保护总局《非污染生态影响评价技术导则》引入的概念框架和理论方法。本文通过景观生态学在不同性质建设项目中的运用分析,进行了一定的尝试,更加希望在今后建设项目生态环境影响评价工作中得到修正和完善。     

An Evaluation of Vernal Pool Creation Projects in New England: Project Documentation from 1991–2000

Vernal pools are vulnerable to loss through development and agricultural and forestry practices owing to their isolation from open water bodies and their small size. Some vernal pool-dependent species are already listed in New England as Endangered, Threatened, or Species of Special Concern. Vernal pool creation is becoming more common in compensatory mitigation as open water ponds, in general, may be easier to create than wooded wetlands. However, research on vernal pool creation is limited. A recent National Research Council study (2001) cites vernal pools as challenging to recreate. We reviewed documentation on 15 vernal pool creation projects in New England that were required by federal regulatory action. Our purpose was to determine whether vernal pool creation for compensatory mitigation in New England replaced key vernal pool functions by assessing project goals and documentation (including mitigation plans, pool design criteria, monitoring protocols, and performance standards). Our results indicate that creation attempts often fail to replicate lost pool functions. Pool design specifications are often based on conjecture rather than on reference wetlands or created pools that function successfully. Project monitoring lacks consistency and reliability, and record keeping by regulatory agencies is inadequate. Strengthening of protection of isolated wetlands in general, and standardization across all aspects of vernal pool creation, is needed to ensure success and to promote conservation of the long-term landscape functions of vernal pools.