锥管件无模拉伸数学模型的研究

此文分析了锥形管件无模拉伸的变形机制,提出了锥管形件无模拉伸速度、冷热源移动速度的变化规律,对锥形管壁厚的变化也提出了相应的数学模型,并通过实验研究证明,本文提出的速度模型,较好地表达了锥形管件无模拉伸冷热源速度变化的规律.     

微波消解在样品前处理中的应用

本文采用微波消解前处理方法对大米、土壤、人发等样品进行前处理,对样品中所含重金属进行测定,其中微波消解前处理方法具有空白小、准确度高、相对偏差小,是较为理想的前处理方法.     

金属材料的超声塑性加工

此文介绍了超声振动在金属塑性加工领域的应用,讨论了超声塑性加工的理论机制和工艺特点,论述了超声场中的材料性能和粘塑性本构关系。     

内凸筋口琴管连续挤压模具

内凸筋口琴管,是汽车空调的一种新型散热管.具有散热效果好、单位面积小、重.量轻等优点.此文介绍了连续挤压内凸筋口琴管模具的设计方法及其模具芯头的冷挤压加工.     

微波消解石墨炉原子吸收法测定土壤中的铅和镉

用微波消解石墨炉原子吸收分光光度法(GFAAS)测定土壤中的铅、镉含量,通过硝酸-氢氟酸-盐酸体系进行土壤样品微波消解,加入磷酸二氢铵基体改进剂消除干扰,该方法具有分析速度快、测定结果的精确度和精密度高、节省人力等特点。     

土壤样品中汞消解方法探讨

在使用ZYG—Ⅱ型智能冷原子荧光测汞仪测定土壤样品时,发现消解液中的盐酸试剂含有微量汞,使土壤中痕量汞的测定无法进行,本文采用巯基棉纤维提纯盐酸试剂并通过标准土样的测定对方法的准确度进行了验证。     

微波消解-ICP-OES法测定蔬菜中的镉

采用微波消解-ICP-OES法测定蔬菜中的镉,选择了最佳微波消解条件,确定了分析线.方法检出限为0.002 μg/L,相对标准偏差为1.1%,加标回收率为100%～104%,与干灰化法作对照试验,测定结果经t检验无显著差异.     

Importance of accounting for the piping system and boundary conditions in determining the maximum surge pressure following heat-exchanger tube-rupture

Shell-tube type heat exchangers are often used to exchange heat between a high-pressure fluid and a low-pressure fluid, and the pressure difference between the two fluids could be significantly high. If the difference in the design pressure between the low-pressure (LP) and high-pressure sides is greater than that covered by American Petroleum Institute (API 520 and 521) 10/13^th rule, dynamic analysis is required to ascertain that the maximum surge pressure that could be reached does not compromise the integrity of the LP side of the exchanger. API guidelines also notes that attention should also be given not only to the shell-side of the heat exchanger under evaluation, but also to the “upstream and downstream systems” This paper offers further insight into the importance of including the surrounding piping systems around the subject heat-exchanger where a tube-rupture scenario is considered, and also directs attention to the importance of correctly specifying the appropriate boundary conditions (B.C.) at the far ends of both the upstream and downstream piping systems. It demonstrates the effects of specifying different B.C. on the maximum pressure surge via a case study of a hot separator vapour condenser in a bitumen hydrotreating unit, where the process fluid on the tube-side is a vapour–liquid mixture at 9660 kPa(g). The vapour mass fraction of the process fluid is approximately 0.5, and is mostly hydrogen. The fluid on the LP side is cooling water connected to the plant supply and return cooling systems as well as another adjacent low pressure condenser. The design pressure for the cooling water piping system and the adjacent condenser is 1380 kPa(g).     

Monitoring of atrazine in milk using a rapid tube-based ELISA and validation with HPLC

Although atrazine has been banned in the European Union since 2007 it still persists in soil from where it can enter the food chain. Milk-producing animals accumulate atrazine from contaminated feed and water and since large quantities of milk and milk products are consumed its quality should be constantly monitored. The objective of this investigation was to develop a simple tube ELISA procedure suitable for use in non-specialised laboratories and in the field. A polyclonal antibody raised in sheep and the hapten-gelatine conjugate was immobilised onto polystyrene tubes. This enables the colour produced to be read on a basic spectrophotometer. Milk samples were collected from three farms in different regions of Poland and diluted before immunoassay was performed. Samples were extracted with hexane-acetone for HPLC analysis. The amount of fat in the milk samples interferes with the dose response so it essential that the standards are prepared in the same samples matrix. A good correlation between 1% and 2% was found between the two methods in the analysis of real samples. However the ELISA procedure was more sensitive that the HPLC method since atrazine was detected in some samples by the ELISA but was not confirmed by the HPLC method. The study demonstrated that the simple antigen-coated tube assay provides a cost effective and valuable screening test that can be easily modified for direct use as a screening tool in the field.     

城市初级污泥的嗜热厌氧消化研究

实验通过运行连续搅拌反应器(CSTR),对城市初级污泥的两步嗜热厌氧消化进行了研究。研究结果表明,同一步嗜热厌氧工艺相比,两步嗜热厌氧工艺运行稳定,具有更高的有机物降解率、病原体的杀灭率,多产出的甲烷气体不仅可以弥补由于预处理而额外消耗的能量,而且还有净能量剩余。