Effect of Temperature and Amount of Flux in a Charge on Structure and Phase Composition of Balkhash Copper Smelter Plant Slags

Metallurgist - Samples of converter slag of the Balkhash copper-smelting plant (BMZ), taken during their discharge from a converter, and experimental samples after conversion under laboratory...     

Processing Converter Slags with Total Utilization of All Components

Metallurgist - Currently, almost all plants converted to autogenous smelting of copper-containing concentrates use flotation of converter slags (CS) while leaving 0.55–0.90% Cu in tailings...     

国际航空货运枢纽港:以航空物流为新竞争优势

20世纪80年代以来,经济全球化促进了亚太地区的一些国家和地区的经济迅速增长,同时也带动了区内航空货运的发展.国际航空货运枢纽港(GTP:Global TransPark)是新经济背景下的一种新型货运机场,对提升区域竞争力有着重要的意义.我国有必要建设GTP,以期在21世纪电子商贸及高科技加工工业的发展上抢先建立滩头阵地.逐渐成熟的香港都会经济区有着"一国两制"的特殊地缘政治和制度优势,因而,在亚洲各竞争中的经济区域中,它是建设亚洲首个、也将是最大的GTP的最佳区位.GTP的建成运作可以提升该都会经济区的总体竞争力,加快其经济重构的步伐.结合区内的其它4个机场,珠海机场有条件发展成为GTP.然而,GTP的建设需要有关机场与地方政府间在关税、制空权、后勤服务以及水陆交通等方面进行协调,这将对该都会经济区的内部合作提出更新的挑战.     

New filters for internal model control design

In this paper we study the design of a new two-degree-of-freedom filter for the internal model control (IMC) method. The new filter alleviates some disadvantages of the standard IMC filter when the IMC method is applied to unstable plants that do not have non-minimum-phase zeros. We show that by employing the new filter, the resulting system has a flatter frequency response, better stability robustness, and little overshoot in the step response. Furthermore, one of its design parameters can be related directly to the closed-loop bandwidth and the other parameter can be used to control the recovery time after an overshoot has occurred in the step response. These features are important in the application of the IMC method to a new approach of adaptive robust control. Examples are given in the paper to illustrate the new filter design.     

Nuclear microscopy of single whole cultured cells: preparation and analysis of human Chang liver cells

Nuclear microscopy is a powerful tool for the measurement of elemental concentrations in single cells. Six methods involving the use of various fixing agents, rinsing agents and drying methods were tried in the preparation of cultured human Chang liver cells for nuclear microscopy and the suitability of each method was evaluated by monitoring the K/Na ratios and shapes of individual cells. The K/Na ratio is a commonly used criteria for the ionic integrity of cells; K/Na ratios well above 1 indicates minimal perturbation of the intracellular ionic composition. Non-stimulated human Chang liver cells in a resting state are usually polygonal in shape and flattened in firm anchorage to the substrate, while dividing or stimulated cells appear rounded. Therefore the shapes of the cells can be used as an indicator of whether the cells are in a resting or stimulated state. It is not desirable for cells to be in a stimulated state since then the effects of other external stimuli cannot be observed independently. Of the six methods tested, chemical fixation, as expected, was considered non-ideal for the preparation of human cultured Chang liver cells. Ice-cold 150 mM sucrose was found to be the most suitable rinsing solution for the preparation of cultured human Chang liver cells. Both freeze-drying and air-drying were used as drying methods and cells processed by either method were found to have K/Na ratios well above 1. Hence both drying methods were found to be suitable although membrane blotting followed by air-drying was preferred as excess rinsing solution can be very quickly removed during the blotting process. The K/Na ratios of cells on the same target holder but from different regions were found to be dependent on the local cell density. Cells which are locally dense-packed were found to have a much higher K/Na ratio than cells in a less dense region.     

大颗粒流化床停留时间分布的研究

通过对流化床尿素造粒的冷模研究，对4种与尿素有类似流化特性的大颗粒物料在两级矩形流化床内的停留时间分布进行了系统的实验研究，分别考察了气速、床高（高径比）、粒径、物料流量等操作变量对停留时间分布的影响。气速是影响停留时间分布的主要因素，随着气速的增加，物料在床内的混合加剧，并同时伴有循环流。大颗粒床层混合程度较差时，更易出现腾涌现象。停留时间分布的测定为流化床造粒器的工业设计提供了基础数据。     

A Low-Power Blocking-Capacitor-Free Charge-Balanced Electrode-Stimulator Chip With Less Than 6 nA DC Error for 1-mA Full-Scale Stimulation

Large dc blocking capacitors are a bottleneck in reducing the size and cost of neural implants. We describe an electrode-stimulator chip that removes the need for large dc blocking capacitors in neural implants by achieving precise charge-balanced stimulation with <6 nA of dc error. For cochlear implant patients, this is well below the industry's safety limit of 25 nA. Charge balance is achieved by dynamic current balancing to reduce the mismatch between the positive and negative phases of current to 0.4%, followed by a shorting phase of at least 1 ms between current pulses to further reduce the charge error. On +6 and -9 V rails in a 0.7-mum AMI high voltage process, the power consumption of a single channel of this chip is 47 muW when biasing power is shared by 16 channels.     

Influences of general computer experience and age on library database search performance

Two experiments examined the effects of general computer experience and age on library system search performance among novice library system users. Twenty younger adults (10 with high and 10 with low computer experience) and 20 older adults (10 with low and 10 with no computer experience) performed 10 search tasks of varying difficulty. Search success, syntax errors, database field specifications, keyword specifications, and use of Boolean operators were examined. Among younger novices, high computer experience was associated with slightly better performance than low computer experience. Among older novices, having some computer experience was associated with much better performance than no computer experience. Older computer users showed lower overall success rates, made more syntax and field specification errors, and demonstrated poorer understanding of Boolean logic and keyword matching algorithms than younger adults with similar computer experience. Implications for interface design and training interventions for novice on-line library system users are discussed.