Cost effective environmental control technology for utilities

On September 24, 1998, new regulations announced by the US EPA require 22 eastern states plus the District of Columbia to develop state implementation plans to reduce ground-level ozone through the reduction of nitrogen oxide (NOx) emissions (Cooper, 1998). This plan calls for a 28% NOx cut in the summer time (1.2 million tons) by 2007. This calls for utilities to develop new, efficient, and robust post-combustion NOx control technologies. A new environmental control technology called low temperature oxidation (LTO) system, which can reduce NOx emissions below measurable levels (i.e. 2 ppm using process analyzers) at low temperature (125-325 °F), was awarded the best available control technology and the lowest available emission reduction technology by the US EPA in April 1998. Ozone is employed to oxidize nitric oxide (NO) to dinitrogen pentoxide (N₂O₅) at a low temperature in an oxidizer, which is then easily absorbed by water in a scrubber. Bench scale and pilot plant tests have shown that the LTO process can almost completely remove the NOx emissions (i.e. NOx emissions are below levels measurable using process analyzers). This proved that the LTO system is an attractive process to meet the stricter NOx regulations. There are multiple benefits of the LTO system besides removal of NOx emissions, includes reduction of SOx and CO emissions, and no secondary air emissions (NH₃, N₂O). In order to obtain minimum NOx emissions, extra ozone needs to be supplied. The cost of the process also increases nonlinearly as emissions decrease. This poses a challenging multiobjective optimization problem where emissions like NOx and SOx need to be minimized, while minimizing the system cost as well as extra ozone. This problem is addressed using a new and efficient multiobjective optimization framework. This framework will provide designs that are cost effective as well as environmentally friendly.     

Trisomy 14 mosaicism leading to cytogenetic discrepancies in chorionic villi sampled at different times

Short- and long-term cultures of chorionic villi obtained in the 11th week of pregnancy revealed trisomy 14. After induced abortion trisomy 14 mosaicism was established in fetal skin and umbilical cord tissue while a second long-term culture of chorionic villi exhibited a normal karyotype. The results of the pathological investigations are discussed with respect to the cytogenetic findings.     

消除电力谐波污染 确保电网运行安全

笔者从维护绿色电力环境、确保电网运行安全的角度出发 ,简述了抑制和消除电网谐波污染意义 ,着重介绍了一种新颖的用于消除电网谐波污染的装置 (有源电力滤波器 )的滤波原理和研究。这种滤波器与传统的LC无源滤波器的区别在于它采用了积极主动的滤波方式 ,将检测到的电网谐波电流经DSP(高速数字处理器 )运算处理后生成谐波补偿电流指令信号 (六路PWM驱动信号 ) ,然后 ,用此信号去驱动由 6只MOSFET管组成的三相逆变电路 ,逆变电路产生谐波补偿电流去抵消电网谐波电流 (谐波补偿电流与谐波电流大小相等、方向相反 )。理论研究和实验结果表明 :在电力系统中使用该装置可动态抑制和消除谐波电流 ,为维护电网运行安全和绿色电力环境提供了必要的技术保障。     

A Comparison of Protocols and Observer Precision for Measuring Physical Stream Attributes1

Abstract: Stream monitoring programs commonly measure physical attributes to assess the effect of land management on stream habitat. Variability associated with the measurement of these attributes has been linked to a number of factors, but few studies have evaluated variability due to differences in protocols. We compared six protocols, five used by the U.S. Department of Agriculture Forest Service and one by the U.S. Environmental Protection Agency, on six streams in Oregon and Idaho to determine whether differences in protocol affect values for 10 physical stream attributes. Results from Oregon and Idaho were combined for groups participating in both states, with significant differences in attribute means for 9 out of the 10 stream attributes. Significant differences occurred in 5 of 10 in Idaho, and 10 of 10 in Oregon. Coefficients of variation, signal‐to‐noise ratio, and root mean square error were used to evaluate measurement precision. There were differences among protocols for all attributes when states were analyzed separately and as a combined dataset. Measurement differences were influenced by choice of instruments, measurement method, measurement location, attribute definitions, and training approach. Comparison of data gathered by observers using different protocols will be difficult unless a core set of protocols for commonly measured stream attributes can be standardized among monitoring programs.     

安全产品的供求特性及其与行业安全形势的关系初探

基于安全经济学的基本原理，通过对不同行业的自动安全水平和法定安全水平之间的关系的分析，论述了不同行业安全产品的需求特性，以及与此相适应的安全产品供给特性；并对安全产品的特殊供求机制与特定行业的安全形势之间的关系进行了初步的探讨，提出了提高行业安全水平的对策。     

电除尘器及其电离荷电机制的研究新进展

详细介绍了电除尘技术研究现状、现存问题及其研究趋势.目前电除尘技术的理论尚不完备,属于经验工程的学科,电除尘器的技术性能优劣取决于设计命中率.为此,论述烟尘荷电凝聚机制并研究电离放电通道中的带电粒子复合问题及其输运特性等,以便解决除尘电场中的电离占空比、输运项甚低等问题;研究了烟尘荷电、凝聚的物理过程,以便进一步提高电除尘器的性能.     

压裂返排废液达标排放的实验研究

油田压裂返排废液由于所含添加剂种类繁多,有机成分复杂,使CODCr值高而处理难度大。本试验以港深11-8井为研究对象,通过大量室内试验,最终采用“混凝—萃取—微电解—活性炭吸附—催化氧化—生化”六步法处理废水。试验结果表明,原水的CODCr从6460 mg/L降至90 mg/L,达到一级排放标准。     

我国环境保护产业发展状况

文章总结了2003年我国环保产业抽样调查情况,分析了产业的基本特点及各分支领域市场发展现状。     

鲜水河断裂带活动期次和滑移特性微观标志的识别

在鲜水河断裂带万木卡等地采集的第四纪形成并遭受变形的石灰华标本显微观测中,发现多期粘滑和蠕滑交替变形的证据;在该断裂带1923年炉霍、道孚间71/4级地震和1973年炉霍雅德7.9级地震震中部位野外考察过程中发现,沿地震断裂面分布有定向排列的砾石和破裂.从这些最新活动断面上采集的变形物质定向薄片显微观测中同样发现与上述类似的微观变形标志.这些发现和标志对鲜水河断裂第四纪以来活动期次与滑移特性的识别及研究具有重要的参考价值.     

深圳市罗湖断裂带活动性及建筑物安全监测系统设计

本文介绍了在深圳市复杂的城市环境里进行断裂活动及建筑物安全监测的思路和方法，以及监测技术系统的构成与布置，以北东向的罗湖断裂带和北西向断裂切割的典型地块及坐落在这些地块上的高层建筑物为重点监测目标，选择一些高层建筑物及水库大坝建立变形监测系统；沿断裂带展布方向布设一定密度的水准环线构成地面垂直变形监测网；布设GPS参考网和相对网，构成地面水平位移监测网。