安达凹陷沙河子组烃源岩层序及地化特征浅谈

安达凹陷沙河子组地层主要发育低水位体系域;水进体系域只在局部发育,范围很小;高水位体系域在全区分布广泛。沙河子组烃源岩以暗色泥岩最为发育,其有机碳平均值为3．88％,热解S1＋S2平均值为1．360mg／g,原始生烃潜力较大;有机质类型以豫型为主;烃源岩Ro范围值为1．71％～2．43％,平均值为2．00％,在凹陷埋藏较浅地区处于高成熟阶段,其它地区Ro均高于2．0％,达到过成熟阶段。安达凹陷从1998年至今累计提交各级别储量,揭示了本区烃源岩较强的生气能力。     

阳信洼陷烃源岩评价

在分析了阳信洼陷烃源岩多种有机地球化学参数的基础上,对其有机质丰度、类型及成熟度进行了研究。结果表明,阳信洼陷沙一段至沙四段上亚段为好一优质烃源岩,沙四段下亚段为差烃源岩。烃源岩有机质热演化划分为3个阶段：未成熟生物气阶段、低熟油生成阶段和成熟油生成阶段。阳信洼陷主力烃源岩在沙三段和沙四段上亚段,这两个层段是今后勘探的重点层段。     

Evaluation of chemical indicators for tracking and apportionment of phosphorus sources to Table Rock Lake in Southwest Missouri, USA

This work evaluated the suitability of selected chemical species as indicators for tracking and apportionment of point and non-point phosphorus sources within the Table Rock Lake watershed in Southwest Missouri, USA. The species were evaluated with respect to their uniqueness to specific source types, their ability to be detected in both sources and receiving waters, and the consistency of their concentration ratios to phosphorus. Four sampling events were conducted at 15 sample locations in one year to collect water samples for measuring the concentrations of total and dissolved phosphorus, seven anions, and 19 major and trace elements. Current analytical methods were sensitive enough for quantification of most of the chemical species in both sources and the receiving waterbody. Due to the high seasonal variation of phosphorus concentrations in source samples, no chemical species had consistent concentration ratios to phosphorus across source types. However, several chemicals were found to be unique to specific sources; bromide ion can be used as a unique indicator for the effluent of the largest wastewater treatment plant in the watershed.     

Genotype diversity of Escherichia coli isolates in natural waters determined by PFGE and ERIC-PCR

Most library-dependent bacterial source tracking studies using Escherichia coli (E. coli) have focused on strain diversity of isolates obtained from known human and animal faecal sources for library development. In contrast, this study evaluated the genotype variation of E. coli isolated from natural surface water using pulsed field gel electrophoresis (PFGE) and enterobacterial repetitive intergenic consensus sequence polymerase chain reaction (ERIC-PCR) to better understand these naturally occurring populations. A total of 650 water samples were collected over a nine month period from eleven sampling stations from Lake Waco and Belton Lake in Central Texas. Of the 650 water samples collected, 412 were positive for E. coli, yielding a total of 631 E. coli isolates (1-12 isolates collected per sample). PFGE and ERIC-PCR patterns were successfully generated for 555 isolates and were compared using the curve-based Pearson's product-moment correlation coefficient. The 555 E. coli isolates represented 461 PFGE genotypes, with 84% (386/461) of the genotypes being represented by individual isolates. The remaining 75 genotypes were represented by 2-5 isolates each. Using ERIC-PCR, the 555 E. coli isolates represented 175 genotypes, with 63% (109/175) of the genotypes being represented by individual isolates. In contrast to the PFGE results, two ERIC-PCR genotypes represented 37% of the E. coli isolates, (83 and 124 isolates, respectively), and were found throughout the watersheds both spatially and temporally. Based on the PFGE genotype diversity of water isolates, there is little evidence that a small number of environmentally-adapted E. coli represent dominant populations in the studied waterbodies. However, with the lower discriminatory power technique ERIC-PCR, an opposing conclusion might have been drawn. These results emphasize the importance of considering the resolving power of the source tracking technique being used when assessing strain diversity and geographical stability.     

Multiple lines of evidence to identify the sources of fecal pollution at a freshwater beach in Hamilton Harbour, Lake Ontario

Multiple microbial source-tracking methods were investigated to determine the source of elevated Escherichia coli levels at Bayfront Park Beach in Hamilton Harbour, Lake Ontario. E. coli concentrations were highest in wet foreshore sand (114,000 CFU/g dry sand) and ankle-depth water (177,000 CFU/100mL), declining rapidly in deeper waters. Many gull and geese droppings were enumerated each week on the foreshore sand within 2m of the waterline. Both antimicrobial resistance analysis and rep-PCR DNA fingerprinting of E. coli collected at the beach and nearby fecal pollution sources indicated that E. coli in sand and water samples were predominantly from bird droppings rather than from pet droppings or municipal wastewater. Both methods indicated a trend of decreasing bird contamination, and increasing wastewater contamination, moving offshore from the beach. When foreshore sand was treated as a reservoir and secondary source of E. coli, waterborne E. coli were found to be more similar to sand isolates than bird or wastewater isolates out to 150 m offshore. Multiple lines of evidence indicated the importance of bird droppings and foreshore sand as primary and secondary sources of E. coli contamination in beach water at Bayfront Park.     

低品位热能利用与减缓气候变暖

低品位热能利用受冷源的制约,其可利用能的温度范围较窄,大部分热能作为废热被排放。本文通过新的制冷循环的建立,探索提高低品位热能制冷效率的方法。新的制冷循环以空气或空气中的主要成分为循环工质,由相互连接、相互影响的气动压缩循环子系统、冷量增益循环子系统和低压补冷循环子系统三部分组成。新的制冷循环以低品位热能作为主要能源,电能作为辅助能源,以期达到更高的能效比,从而使制造冷源成为可能。提高低品位热能的利用率,对减缓气候变暖发挥重要作用。     

Design and implementation of a VSC for interconnection with power grids,using the method of identification the system through state space for the calculation of controllers

The paper presents the analysis, design and results of a Voltage Source Converter (VSC) when applying PID Controller. Results were obtained through digital simulation and through physical implementation. VSC allows to control independently the active power and reactive power flow injected to the grid. PID controller was implemented considering the system model. The model is obtained through of the identification using state space.     

造船系统直流手工电弧焊电源选型论证

本文通过船厂焊接工况条件的评价体系,进行船用焊机选型论证、焊接电源外特性、技术经济指标对比后,认为ZXE1-400、500交直流两用弧焊机系船厂用焊接设备的优选品种。     

基于CPLD控制的DDS数字频率合成器设计

介绍了ADI公司新一代DDS芯片AD9952和XILINX公司新一代CPLD产品XC2C128的主要性能，提出了用XC2C128作控制电路，由AD9952构成宽带、低相噪、低功耗数字合成频率源的设计方案，同时对如何提高DDS频谱纯度进行了探讨，给出了超宽带应用电路解决方案。     

钴源退役过程的辐射防护与剂量监测

辐照技术的应用日益广泛，辐射源的退役也越来越受到关注。苏南某单位辐照室建立于20世纪80年代初，2001年4月对最早投入运营的39根钴源进行退役，退役过程分三个阶段，历时48小时。由于经过了精心的准备，采取了有效的防护措施，退径过程没有出现工作人员受超剂量照射的情况。