压力脉冲波法天然气管道堵塞检测研究*

为快速检测出天然气管道堵塞位置、长度及堵塞程度,解决天然气输运管道中堵塞定位难题,探讨压力脉冲波法管道堵塞检测的可行性与效果。搭建长220 m的压力脉冲波堵塞检测实验系统,进行多组连续性长堵塞检测实验和水堵检测实验。结果表明:连续性长堵塞检测实验中堵塞前沿反射信号为负压波,堵塞后沿信号为正压波,且波形清晰可辩,其多组实验的堵塞位置、堵塞长度及堵塞率的平均检测误差分别为0.23%,0.75%和2.67%;水堵反射信号清晰可辨但波形复杂,其多组实验的堵塞位置、堵塞长度及堵塞率的平均检测误差分别为0.78%,9.61%和43.28%。实验结果有效地证实了压力脉冲法的可靠性与实用性,并为压力脉冲波法堵塞检测现场应用提供指导。     

Effect of fulvic acid on the photochemical degradation of methylparathion

Photochemical degradation of methylparathion (O,O,–dimethyl O-4 nitrophenylphosphorothioate) in the presence of fulvic acid (FA) between pH 2 and 7 was studied by differential pulse polarography (DPP). Fulvic acid and its photoproducts were not electro-active under the experimental conditions used in this study, and only the pesticide exhibited polarographic signals. Photolysis of methylparathion in acid media was sensitized by fulvic acid since the pesticide did not degrade in the absence of this compound. Methylparathion degradation was observed at each of the studied pHs. The reaction was first-order with rate constant values ranging from 3.3 × 10^?3 to 8.8 × 10^?3min^?1.     

A simple and reliable method of chromosome banding for prenatal cytogenetics using a bromodeoxyuridine pulse

An extremely simple, fully defined and reliable technique for banding chromosomes in situ is described. The method uses a pulse of bromodeoxyuridine to produce replication pattern banding complete with G- and C-type banding in the same karyotype. This enables immediate resolution of problems otherwise requiring extra subculturing and the application of conventional banding techniques. The value of routine chromosome banding in prenatal cytogenetics using such an economical technique is discussed.     

Optimal Harvesting of the Norwegian Spring-Spawning Herring: Variable Versus Fixed Harvesting Strategies

In this paper we study optimal harvesting of the Norwegian spring-spawning herring stock. The biological model is described by a discrete time age-structured model. The optimal harvesting patterns are studied numerically and the results show that when using a linear cost function and constant price in the optimisation model, the optimal harvesting pattern is pulse fishing. However, optimal constant fishing effort gives only slightly lower profit. Moreover, when price is made responsive to harvest the optimal harvesting strategy is substantially smoothed. This revised version was published online in July 2006 with corrections to the Cover Date.     

低温等离子体治理H2S污染的实验研究

低温等离子体技术是一种高效、快速的污染消除技术,国内外都在对其进行广泛而深入的研究.采用脉冲电晕放电等离子体对空气中的硫化氢进行降解研究,探索了、脉冲峰压、脉冲频率、气体流量以及气体初始浓度对净化效果的影响,气体浓度由气相色谱仪测定.结果表明,脉冲电晕放电可以有效消除硫化氢污染,净化率随脉冲峰压和脉冲频率的增加而提高,随气体初始浓度和流量的增加而下降,且在初始浓度360 mg/m3、流量1200 mL/min、脉冲峰压30 kV、脉冲频率80 Hz的条件下,处理后的气体中已检测不到H2S,根据色谱检测限(0.29 mg/m3)计算出的净化率≥99.92%.采用离子色谱对产物进行了定性分析,发现H2S经放电处理后主要产物为SO2和SO3.     

百叶窗式脉冲静电除尘技术的研究

对沸腾炉百叶窗式脉冲静电除尘技术模拟实验，对模拟装置的电场分布，收法面积、除尘效率等参数之间的关系做了较为深入的分析，对实验除尘器的除尘效果和运行情况进行了讨论。     

铁阳极交变低频脉冲电源处理甲基橙模拟废水的研究

研究了在铁板阳极交变低频脉冲电絮凝法处理甲基橙模拟废水过程中，电流强度、通电时间、进水浓度以及交变脉冲时间对废水色度及COD去除率的影响，并总结出该法降解水中甲基橙的一般规律。     

Barley lipid-transfer protein as heavy metal scavenger

A lipid-transfer protein was isolated from a domestic cultivar of brewers barley grain, Hordeum vulgare. The presence of Cu (II), Pb (II), Cd (II) and Zn (II) ions in its structure and its ability to bind Hg (II) and Ni (II) ions is known. We investigated its ability to bind other metal ions by differential pulse polarography. Here we demonstrate that the lipid-transfer protein has an affinity to bind Co (II) and Pb (II) and has no affinity towards Cd (II), Cu (II), Zn (II) and Cr (III). These results suggest a new possible role of barley lipid-transfer protein for phytoextraction.Selected article from the Regional Symposium on Chemistry and Environment, Krusevac, Serbia, June 2003, organised by Dr. Branimir Jovancicevic     

飞灰和水在脉冲放电脱硫中作用的研究

为探讨脉冲放电脱硫和除尘结合的可行性 ,研究了飞灰和水对脉冲放电脱硫的影响。飞灰对脉冲放电脱硫影响不大 ;水对脉冲放电有明显抑制作用 ,但能显著提高脱硫效果 ,提高能量效率 ;飞灰和水协同作用对脱硫有利 ,不加氨时脱硫率达 1 6 2 % ,添加氨时电晕脱硫率达 30 5% ,总脱硫率 80 2 %。     

静电除尘预荷电的研究

采用微小颗粒粒径和电荷同时测量装置以及高压方波电源和纳秒（ｎｓ）高压窄脉冲电源，对用于静电除尘预荷电的负电晕放电荷电器进行了实验研究和理论分析，探讨了其荷电性能和规律，并提出了适用于预荷电器的新的理论荷电计算方法。