滤膜法检验水中总大肠菌群方法中一些问题的探讨

建立滤膜法在检测总大肠菌群的关键步骤。要使大肠杆菌的检验结果比较能正确反映被检水中的大肠杆菌群得数量,应选取适量水量,并应作两份平行检验     

浅议滤膜法检验水中总大肠菌群方法有关问题

水质细菌学检测是水质分析中的重要指标,其对于保障居民饮用水安全具有关键指导意义。本文作者基于多年水质检验的实践工作经验,从理论依据、操作步骤及注意事项等方面对滤膜法检验水中总大肠菌群方法有关问题进行探讨,以期在实践工作中具有借鉴作用。     

水环境中两种大肠菌群标准检测方法的对比研究

大肠杆菌是人及各种动物肠道中的正常寄居菌,食物或水中大肠杆菌的检出即意味着直接或间接的近期粪便污染。在检测原理和步骤、适用范围以及检测结果等方面对两种常规的大肠菌群检测方法作了对比研究。     

饮用水中大肠杆菌标准检验方法及仪器化进展

大肠杆菌是饮用水重要的微生物指标细菌,目前的标准检验方法有多管发酵法、膜过滤法、酶底物法。由于饮用水的测试量迅速上升,以及对现场快速检验方法的需求,为降低分析人员劳动强度,减少人为误差,提高分析效率,市场开始研制和生产基于酶底物法的大肠杆菌检测仪器。     

松北湿地水质中粪大肠菌群的测定

湿地被为"自然之肾",具有独立特殊功能的生态系统。它是自然界最富生物多样性的生态景观和人类最重要的生存环境之一,不但具有丰富的资源,还具有巨大的环境调节功能和环境效益。粪大肠菌群是判定水体水质要指标之一,水中的病原菌多数来源于病人和病畜的粪便。本文介绍了利用多管发酵法检测哈尔滨松北湿地内的粪大肠菌群数的实验。     

粪大肠菌群的测定——多管发酵法

对地表水和废水中粪大肠菌群目前通用的多管发酵检测方法进行优化。本文结合作者多年的工作实践对粪大肠菌群的测定方法（多管发酵法）进行分析探讨。     

沙门氏菌检测方法的探讨

本文提出了一种检验沙门氏菌的方法-酶底物法．应用β-萘酚辛酯酶为底物,经沙门氏菌酶解,释放出β-萘酚,与固兰作用出现的紫色,能够在短时间内得到检验结果,反应在纸片上进行。通过一定的实验,确定了酶底物法适用于基层小实验室使用。经过与三种现有的沙门氏菌检验方法比较,证明该方法是快速且有效的。     

检测耐热大肠菌群培养基的质量控制方法探讨

培养基的质量是微生物检测工作的基础,直接影响检测结果的可靠性。本文结合实际情况,从外观、pH值、无菌检查及灵敏度检查等几个方面,对检测耐热大肠菌群所用EC培养基的质量控制进行讨论,以便微生物实验室不断完善和提高培养基的质控水平,从而保证检验结果的准确性。     

酶底物法和国标法测定饮用水中菌落总数的比较

本文使用酶底物法和国标法对地下水、水源水、饮用水中菌落总数进行了监测,结果经统计学检验,两种方法监测结果的P值小于0.5,无显著性差异。酶底物法可以替代国标法用于评价饮用水中微生物。     

三种检测微囊藻毒素的ELISA方法比较研究

建立了抗原抗体复合物酶联免疫法(anti-immune complex ELISA,ICELISA)、间接竞争酶联免疫法(Indirect cELISA)、直接竞争酶联免疫法(Direct cELISA)三种检测微囊藻毒素的酶联免疫方法,确定了每种方法的检测限、线性范围以及重现性。以三种方法分别对标准品、藻样、水样及水产品中微囊藻毒素进行了测定,并对三种分析方法进行了较为系统的比较研究,为微囊藻毒素ELISA试剂盒的研制奠定了基础。     

A comparative study of fatigue estimation methods for single‐spot and multispot welds

Fatigue life and load data of spot‐welded samples were obtained by performing tensile‐shear fatigue tests on single‐spot‐welded samples, and by collecting published data on tensile‐shear fatigue tests of multispot‐welded samples. Finite element models of the spot‐welded samples were then constructed, and their accuracy was validated by comparing their results with those of static loading tests. Methods to estimate fatigue in spot‐welded joints proposed by Sheppard, Rupp, and Swellam were used to predict the fatigue life of each sample, and their results were compared. The sensitivity of each method to spot‐welding parameters, as well as the arrangement and number of welded spots, was analyzed to obtain their scope of applicability. Finally, the Sheppard and Rupp methods were used to obtain fitted fatigue curves of each spot‐welded sample, and the equivalent life method was used to generate P‐S‐N curves of the single‐spot‐ and multispot‐welded samples. This method can serve as a useful reference for fatigue reliability analyses of mechanical parts with spot‐welded joints.     

A study on an estimation technique for the transverse impact of plates

This paper describes a numerical algorithm to determine the response of the structure due to a known force. The inverse dynamics problem in structural dynamics is to estimate the unknown forcing function using dynamic response. Theory of plates is employed to solve inverse problems in elasticity with specific applications to position and force sensing. In this paper, the contact force during the transverse impact of a plate is given and the response is solved. A Kalman filter technique was used to numerically estimate an applied force on the plate with the numerical response by an inverse method. In order to examine the accuracy of the proposed method, the plate is subjected to four type forces, which are triangular, sinusoidal, rectangular and random force. The estimated results have a good agreement with the exact values in all cases tested. Copyright © 2001 John Wiley & Sons, Ltd.     

A study on open shop scheduling to minimise total tardiness

This paper deals with open shop scheduling to minimise total tardiness. Contrary to other scheduling problems (i.e., flow and job shops), the formulation of the open shop is given far less attention in the literature. Therefore, we intend to fulfil this gap by the presentation of four different mixed integer linear programming models. We compare the models on the basis of their complexity sizes. Furthermore, we propose two metaheuristics based on genetic algorithm and variable neighbourhood search. We exhaustively explore the effect of different operators and parameters on the performance of genetic algorithm by means of Taguchi method. Two computational experiments are conducted to evaluate the models and algorithms for performance. The first one includes small-sized instances by which the models and general performance of the algorithms are examined. The second one consists of three well-known benchmarks by which we further evaluate the algorithms. The results show the effectiveness of the proposed models and algorithms.     

连续流动法测定烟草水溶性糖的影响因素

为提高RFA-300连续流动分析仪测定烟草及烟草制品中水溶性糖含量的准确性.依据行业标准YC/ T159—2002对各种影响因素进行了考察,发现标准样品的种类、纯度及反应时间是主要影响因素,并根据试验结果和测试原理的要求对仪器管路进行了适当的加长。确定了以葡萄糖为标样.采用校正标样和加长仪器管路的连续流动法测定烟草制品中的水溶性糖。结果表明,改进后方法的回收率为98.8%-107.9%,变异系数为1.63%. 测定结果与芒森·沃克法的基本一致。     

3种不同前处理方法测定卤粉中铅含量的比较研究

比较3种不同前处理方法对卤粉中铅含量测定结果的影响。分别采用微波消解、湿法消解、干法灰化对样品进行前处理,采用石墨炉原子吸收法测定。微波消解耗时短,酸用量小,回收率较好。湿法消解耗时长,酸用量比较多,回收率较高。干法灰化耗时较长,酸用量小,由于灰化温度较高,元素有一定损失,回收率偏低。3种前处理方法均适用于卤粉中铅含量的测定。其中微波消解耗时短,酸用量小,回收率较好,是一种比较好的方法。     

确定毛细管尺寸的当量方法研究

在类比法和当量法基础上，提出多根毛细管之间长度、内径相互转换的当量方法。指出毛细管的摩擦系数对当量转换公式有直接的影响。计算表明，当N／Neq=1．5时，采用不同毛细管摩擦阻力系数进行毛细管当量长度的计算结果差别在6％以内。以制热量为8．5kW和9．85kW的空调机组采用的毛细管为基准，通过类比方法和笔者提出的当量方法计算制热量18kW的空调机组应采用的毛细管的几何尺寸。实验表明：以8．5kW机组为基准时，毛细管内径和长度的计算值和实验值分别相差-7．2％和2．9％；以9．85kW机组为基准时，毛细管内径和长度的计算值和实验值分别相差-6．5％和12．7％。实验说明笔者提出的方法可以用来指导空调机组的毛细管匹配实验。     

三个国标中甲醛测定方法的比较和探讨

对GB 18582-2001、GB 18583-2001、GB/T 15516-1995三个国家标准中甲醛含量测定方法进行了比较,指出了其异同点,并提出了笔者对标准的一些理解和看法。     

硅藻土-莫来石陶瓷负载SiO2膜的制备与表征

将液晶模板技术与溶胶 -凝胶法相结合 ,制备了硅藻土 -莫来石陶瓷 (K -M )负载型SiO2 膜 .表征实验结果表明 :SiO2 膜层与TiO2 过渡膜层间通过Si—O—Ti键的价联方式形成了紧密、稳定的化合型复合膜 ;SiO2 膜孔径集中在 4～ 5nm ,孔分布较为均匀 ;K -M负载SiO2 膜管对气体具有较强的渗透能力 ,并有较好的气体分离作用 .根据实验结果探讨了模板剂的性质及用量对SiO2 膜孔结构的决定性作用 .     

A numerical study on heat transfer of the nanofluid flow inside helical tube through the two-phase method

In this study, a new numerical investigation was carried out to study the heat transfer characteristics of nanofluid flow inside a copper helical tube under constant heat flux. A nanofluid with different particle weight concentrations of 0.5%, 1.0%, and 2.0% was used. The effects of different parameters such as Reynolds number, nanofluid particle concentration, and constant heat fluxes (1500 and 3800?W/m²) on heat transfer coefficient were studied. For validation, Nusselt number and convection heat transfer coefficient obtained from the numerical model was compared with the experimental results. Also, to verify the accuracy of the method, grid independency was studied for each heat flux. The observations showed that the heat transfer coefficient increased by using nanofluid instead of base fluid. In addition, the convection heat transfer coefficient performance improved by increasing the nanoparticles’ concentration. The results from the numerical simulation compared with the experimental data showed that this new numerical method has high accuracy and could correctly predict the heat transfer behavior of nanofluids with different weight particle concentrations under constant heat flux.     

An experimental study on the comparative assessment of hydraulic bulge test analysis methods

An in-depth understanding and full characterization of mechanical behavior for sheet materials are required since it is critical to establish the highly reliable material models over a broad range of strain levels for accurate modeling and analysis of sheet material deformation processes such as stamping, hydroforming, deep drawing, etc. Hydraulic bulge testing of sheet materials has been known to provide flow stress properties at higher strain levels compared to commonly used tensile tests mainly due to the fact the tested specimens are strained under biaxial loading conditions. However, analysis of the hydraulic bulge test data has not been standardized yet as there have been numerous approaches developed and adopted throughout the years. In this study, different approaches for the analysis of hydraulic bulge were compared with experimental results to determine the best combination in obtaining accurate flow curves models at room and elevated temperature conditions for different lightweight materials of interest for several industrial applications (AA5754 and AISI 201). It was determined that Panknin’s bulge radius and Kruglov’s thickness calculation approaches are the best combination to accurately obtain the flow curves at both cold and elevated temperature conditions.