Evaluating and monitoring nucleation and growth in copper foil

The electrodeposition of copper foil for use in electronic materials applications is a complex and demanding process. The specific aspects of producing and controlling the structure-property-performance requirements of the foil are important because of the stringent demands placed on their use in printed circuit boards and similar products. In this paper, a brief review of the electrodeposition process for raw copper foil is presented. Since electrolyte additives play such a significant role in the copper-depositionprocess, the effects of two essential additives, chloride ion and an organic (e.g., glue or gelatine), on the foil are described. Also, the influence of other operating parameters on the initial nucleation, growth, and subsequent electrocrystallization are discussed. Selected characterization methods, such as polarization and scanning electron micrography techniques, are described as a means of monitoring the process, but universally accepted methods of evaluating and controlling the additives and foil quality during electrolysis are still being sought.     

Inhibition of acid rock drainage from uranium ore waste using a conventional neutralization and precipitation treatment

Glass columns (length 50 cm, i.d. 4 cm) containing 900 g of uranium ore waste were subjected to a three-step process: (1) acid drainage generation, (2) neutralization and precipitation treatment and, again, (3) acid drainage generation. In the first acid generation step, lasting about one year, different variables (pyrite addition, inoculation and irrigation solution) were tested by measuring effluent pH, redox potential, total iron and sulphate. Conditions of acid generation were satisfactorily reproduced, reaching stable pH values around 2.0 that were determined mainly by pyrite addition and the type of irrigation solution used (distilled water or ferrous sulphate). The neutralization and precipitation treatment consisted of alternating irrigations of a neutralizing solution (CaO saturated plus NaOH) and a precipitating solution (ferric sulphate saturated). This treatment caused accumulation of basic iron sulphate and iron oxide precipitates according to SEM studies. After this treatment, the barrier effect created by the reaction products was checked, using irrigation solutions similar to the first step. The effluents collected showed higher pH and lower redox potential, total iron and sulphate values than those observed before the treatment, evidencing inhibition of acid drainage generation.     

Springback analysis of thin rectangular bars of non-linear work-hardening materials under torsional loading

A theoretical analysis of the springback of narrow rectangular strips of non-linear work-hardening material under torsional loading has been carried out. This theoretical analysis is supported by experimental results for rectangular mild steel strips of different thicknesses and lengths. Finally an analytical generalized expression relating angle of twist to twisting moment and residual angle of twist per unit length for rectangular strips under plastic torsion is obtained in non-dimensionalized form. A comparison between the results obtained for bars of non- linear and linear work-hardening materials loaded under torsion is also made.     

The onset of vortex instability in laminar forced convection flow through a horizontal porous channel

The onset of convective instability in a fluid-saturated porous layer between the two horizontal plates heated isothermally from below has been analyzed theoretically by using propagation theory. In the analysis the thermal dispersion coefficient is assumed to be proportional to the streamwise velocity. The results show that both inertia and thermal dispersion stabilize the system.     

膨化硝酸铵晶体特性研究

膨化硝酸铵是一种改性硝酸铵晶体,具有显著自敏化特征,成功应用于各类膨化硝铵炸药及震源药柱中.在膨化剂(表面活性剂)的作用下改善了膨化硝酸铵的物理性能和晶体结构及其特征.本文通过硝酸铵固体表面接触角的测量,算出了膨化硝酸晶体表面能;利用差热分析(DSC)技术给出了膨化剂对硝酸铵晶变的影响;采用x射线衍射分析了膨化硝酸铵晶体的晶格特性.     

激光导向伺服系统中满意PID调节器的LMI设计

利用带有图像处理功能的小型激光导向伺服系统,可以大大降低目标坐标测定仪操作手跟踪动态飞行目标的操作难度,从而提高激光回波率.与经典的矩阵分解方法不同,本文以线性矩阵不等式方法,研究了激光导向伺服系统的满意PID调节器设计问题.首先从约束指标的相容性出发,给出满足与给定圆形极点约束相容的输出方差的取值范围.然后,在此取值范围内,得到了求取同时满足上述两种约束的PID调节器参数的方法.靶场试验结果证明了其有效性.     

Using bald eagles to indicate the health of the Great Lakes' environment

The bald eagle (Haliaeetus leucocephalus) is one of the most studied birds of North America, and a great amount of natural life‐history information, including the response of various stressors on the eagles' ability to reproduce, are well known. In Michigan, the eagle has been chosen to track the trends of bioaccumulative compounds of concern across watersheds in the state. The state has been divided into major watersheds, and 20% of these are surveyed each year. A control area in northern Minnesota, Voyageurs National Park, is also sampled annually. We report here on the methods used, the preliminary results of the 1999 field season, and how differences in mercury concentrations varied over a 10‐year period. Mercury in feathers of nestling eagles declined over time only in Lakes Michigan and Huron, but have not decreased among other subpopulations in Michigan. Concentrations of polychlorinated biphenyls (PCBs) and 4,4′‐DDE in blood plasma from nestling eagles have declined over time for most subpopulations; however, they remain greater for breeding areas associated with the Great Lakes' food web. Sea eagles of the genus Haliaeetus are a good sentinel species to track trends in bioaccumulative compounds in aquatic systems.     

Micro-Analysis of the Contact Zone of Tribologically Loaded Second-Phase Reinforced Sol-Gel-Abrasives

Abrasives manufactured via the Sol-Gel route have increased the grinding efficiency of conventional abrasive grinding tools to a remarkable degree in the past ten years. Little is known, however, about detailed wear mechanisms of the abrasive on a nanometer scale. Sliding tests on a pin-on-disk tribometer and single grit scratching tests have therefore been performed in order to identify the wear mechanisms of these innovative materials. TEM-analysis has revealed that severe plastic deformation combined with both crack bridging and crack deflecting effects in the second phase characterise the abrasive rim zone. The surface of the abrasive is covered with an oxide debris layer which substantially improves the tribological behaviour.