Baseline assessment of metals and hydrocarbons in the sediments of Lake Mulwala, Australia

An assessment of hydrocarbon and metal/metalloids (arsenic, cadmium, copper, lead, mercury, selenium, zinc) contamination in sediments from Lake Mulwala, Australia, was undertaken. The objectives of the study were: (i) to determine the extent of contamination in the lake sediments, compared to Australian and international sediment quality guidelines, and (ii) to attempt to identify the contaminant sources to the lake. With the exception of a few samples containing elevated levels of arsenic and/or mercury, the levels of all contaminants in the sediment samples taken from the lake were below the ‘lower trigger’ of the Australian Sediment Quality Guidelines that would warrant further investigation. High molecular weight hydrocarbons (up to 700 mg kg⁻¹) were found in most sediment samples. Non‐metric statistical analysis indicated that the contaminant distribution was different in different parts of the lake, with the lowest concentrations generally found at the influent to the lake. No definitive source(s) of contamination could be identified for either metalloids or hydrocarbons.     

Development of ultra light magnesium-lithium alloys

Magnesium-lithium alloys are among the lowest density metallic materials. Addition of lithium, with a relative density of 0·53, in magnesium reduces the density of the alloy significantly. Furthermore, addition of nearly 11 wt.% lithium converts hexagonal close packed structure of pure magnesium to a body centered cubic lattice, markedly improving formability of the alloy. The development of these alloys, however, had been hampered due to the high reactivity of lithium and magnesium in the molten state and also, due to poor creep resistance and instability of mechanical properties at room temperature. In an attempt to indigenize these ultra light alloys for possible applications in Indian satellite programme, detailed research work was initiated in DMRL. The difficulties associated with producing sound cast ingots have been overcome by controlling melting and casting parameters of these alloys. Extensive work has been done on structure-property correlation of alloys with varying lithium content and minor alloying additions. Based on these work, advanced magnesium-lithium alloys have been developed with improved tensile properties, room temperature stability and creep resistance. Wrought products (plates/sheets) of magnesium-lithium alloy have been supplied to ISAC, Bangalore and are being used in their INSAT-2 programme. This paper describes the systematic studies carried out in the laboratory to indigenize these ultra light alloys.     

结构强度储备的评估及结构维修过程的跟踪决策

本文提出了已建成结构在服役过程中构件的强度储备比和结构整体的强度储备比的概念和定义,它们都是随结构使用和维修过程而变化的时间的函数。我们建议以实际的强度储备比作为构件和结构服役安全度的表达方式,给出了构件和结构强度储备比的具体评定方法,并以结构整体的强度储备比作为控制参数决策结构的维修过程,以求得结构全寿命维修的优化控制。本文所提出的方法适用于具有良好的结构重分析程序和精密细致的检测手段的工程。一般重要的结构工程,例如核电站、海上结构、航空航天设备等均具备上述条件。因而本文所提的方法非常实用,可以立即应用于重要的工程项目,具有重大的经济和社会效益。     

高架桥中异形板裂缝的分析与加固

从分析某高架桥中异形板板底裂缝的特点及成因着手 ,对设计与施工工艺诸方面提出防止裂缝的对策和对裂缝进行加固的全过程。     

Variation in Malting Quality and Heat Resistance in the Malting Barley Variety “Alexis”

In earlier studies concerning vigour, where subsamples are heat‐treated before germination there was found heat‐sensitive as well as heat‐resistant barley samples. The vigour model developed by Ellis and Roberts and further developed at Carlsberg, could only describe the heat‐sensitive barleys. Seventeen samples of the “Alexis” variety grown widely in Europe were collected from the EBC trials in 1994 in order to see if heat resistance in barley was influenced by different growing conditions. We found both heat‐sensitive samples following the vigour model as well as pronounced heat‐resistant samples, but these were not divided according to growing conditions. The germination curves dependent on heat treatment and germination time were evaluated by Principal Component Analysis (PCA). Heat‐resistant barley samples could be differentiated from heat‐sensitive samples already after ½ h of heat treatment at 68°C (12% moisture) and after 3 days of germination. The barley samples were analysed with regard to malting quality. The PCA evaluation of the data divided the samples according to growing location, mainly due to differences in protein and β‐glucan. However, the malting analyses could not describe the differences in heat resistance and sensitivity of the barleys. The biochemical background of the heat resistance found is discussed on the basis of literature. Our findings should give an experimental basis for exploiting a biochemical principle for heat resistance, which is formed during grain filling and consumed during storage and germination.     

天然气的储存

随着能源结构的调整,天然气在一次能源中的比重逐步增大,天然气的储存成为人们日益关注的课题,作者就此作一综述。     

A load dispatch method using fractional programming and semidefinite programming

This paper describes a load dispatch method which minimizes power cost—[fuel cost]/[electric output]—for a power system with thermal plants and energy storage facilities. The proposed method employs fractional programming to convert a minimization problem with fractional objective function to a series of quadratic minimization problems, and semidefinite programming to solve converted problems. The method provides the optimum time‐dependent power output/input and storage level of energy storage facilities as well as time‐dependent power output of thermal plants. The method has been applied to a power system with five thermal plants, two energy storage facilities of various performances, and five load demands. The optimum load scheme of four time mesh points is obtained for the thermal plants and energy storage facilities. The fractional programming successfully converges the optimal scheme through a few iterations. The semidefinite programming deals with a variable matrix of 164 dimensions, and 185 inequality constraints. © 2001 Scripta Technica, Electr Eng Jpn, 138(2): 49–58, 2002     

注浆法在已建油罐地基加固中的应用

在一定的压力作用下,将水泥浆注入松散的地基土中,浆液凝固后将松散的土粒固结在一起,对地基进行加固。这种方法具有省时、省工、省费用、使用简单方便等优点。特别是对已建油罐地基的处理更有其独到之处。由于钻孔可在任意角度下进行,因此可对罐基础任何区域进行加固并达到较好的效果。文章对钻孔布置、钻孔、注浆花管布置、压力灌浆、充水预压等几项关键技术进行了较详细的论述。     

关于CEA混凝土膨胀剂的若干技术问题--与游宝坤同志讨论

作者阐述了CEA膨胀剂混凝土的膨胀量较大，干缩小，抗裂性能良好的特性，CEA与粉煤灰掺用提高强度，改善界面过渡层的性质，提高耐久性；CEA混凝土无Ca（OH）2溶出问题。文中列出GBJ119应用技术规范，说明CEA可用于防水工程。     

新型哈氏合金G—30的耐蚀性能与工业应用

文章叙述了新型镍基耐蚀哈氏合金G-30在不同介质中的耐蚀性能以及工业应用,综合分析了该合金应用的经济性及前景。