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This paper presents an experimental and numerical study of the impact of a particle stream onto a particle bed using a 2D slot model. The numerical simulation is performed by means of the discrete element method (DEM). The results show that the DEM simulation can reproduce the experimental results well under comparative conditions. The dynamics in the formation of a crater is then analyzed in terms of velocity field, force structure, bottom stress distribution and energy exchange based on the DEM results. It is shown that as a result of impact by the falling particles, the particles in the top central region of the particle bed have relatively large velocities and contact forces. The velocities and forces propagate into the bed, and reach the bottom of the base layer quickly. They then continue to propagate leftwards and rightwards to create a crater. During the impact process, most of the energy from the falling particles is dissipated due to the inelastic collision and frictional contacts between particles, and only a small amount of the energy contributes to the formation of the crater. The crater size is shown to be affected by the discharging rate, discharging height and materials properties, and be related to the ratio of the input energy from the falling stream to the inertial energy from the original packing.

Metallothioneins (MTs), containing over 33% cysteine content and lacking both aromatic amino acids and histidine, are metal binding proteins with low molecular weight (7-14 kDa). The metal ions are bound exclusively through thiolate coordination complexes which involve all 20 cysteine residues (Dunn et al. 1987). The MTs can be induced by and bind metals such as cadmium, copper, mercury, silver and zinc (Roesijadi 1992) and are capable of binding 6-7 atoms of cadmium or zinc per mole (Kagi and Schaffer 1988; Hamer 1985). The metals bound to MTs can be removed by exposure to low pH. MTs exist in vertebrates, aquatic invertebrates (Roesijadi 1992), certain bacteria (Olafson et al. 1988) and fusion yeast (Hamer et al. 1985). These proteins are found most abundant in liver, kidney, pancreas and intestine of animals, and the expression of these proteins showed a dose-response relation with the degrees of heavy metal pollution. Expression of MTs has also found to be induced by steroid hormones, interferons, certain chemicals, hepatotoxic solvent, and stresses (Kagi and Schaffer 1988). MTs have been implicated in the involvement of metabolism of copper and zinc (Cousins 1985), and in detoxification of pollutant metals, such as cadmium and mercury (Kagi and Kojima 1987). Moreover, MTs have been indicated to be an efficient scavenger for free OH(Dunn et al. 1987).

A process fault identification and classification scheme for an automobile door assembly process is presented based on multivariate in-line dimensional measurements and principal component factor analysis. First, the door assembly process and the dimensional measurement system are briefly introduced. Second, the technique of principal component factor analysis is presented for process fault identification. Process faults are summarized based on off-line identified case studies. Finally a machine classification scheme based on principal components and principal factors is presented and evaluated, using the pattern knowledge obtained off-line. This scheme is shown to be effective in classifying process faults using production data.

A systematic approach is presented to obtain the best door gap quality through optimal door fitting in automobile body manufacturing. First, three indexes of gap quality are defined; they are: (1) door gap width deviation relative to design nominal; (2) door gap parallelism; and (3) car-to-car gap consistency. Then the door-fitting problem is formulated into a general constrained optimization problem. The effects of optimal door fitting on the three quality indexes are evaluated through computer simulation. These results provide a lower bound on the design of nominal door gap by considering process capability. Finally, a computer-aided fixture adjustment scheme is developed to orient a door in a body side opening to achieve the optimal fitting. The amount of adjustment, with the desired orientation obtained from optimization, is calculated based on parametrically modeled local surface features of the fixture and the door. The adequacy of door feature modeling is verified through a door-fitting experiment.

A two-stage strategy has been used to design an optimum multifacet drill (MFD) for crankshaft drilling. In the first stage, a heuristic MFD was developed by adding an additional facet to the outer corner of the conventional split-point drill. Under accelerated life test conditions, this new drill can decrease thrust force by 21.0% and increase drill life by 50% compared to a split-point drill. In the second stage, compre-hensive force models for predicting thrust and torque were modified and developed. Using the force mod-els, point optimization was carried out to design the optimum MFD. This new MFD can further decrease the thrust by 21.3 % over the heuristic MFD, and accelerated life tests haveshowna25% further increase in drill life.

The hallmarks of Reye's Syndrome which include hyperammonemia, elevated liver enzymes and progressive encephalopathy, have been associated with certain inherited metabolic disorders, thus, current recommendations are to screen atypical Reye's Syndrome cases for defects in amino acid, organic acid and carbohydrate metabolism. Hereditary isolated glucocorticoid deficiency(HIGD) is characterized by undetectable cortisol levels, normal mineralocorticoids and elevated ACTH levels while molecular analysis has demonstrated a point mutation in the MC2R gene of the ACTH receptor in some cases. The presenting symptoms of HIGD in early childhood have been hypoglycemia and/or hyperpigmentation. A 3 5/12 year male with expressive language delay and at least one previous unexplained episode of ataxia had a metabolic evaluation which yielded normal levels of plasma carnitine and non diagnostic urine for amino and organic acids. At 3 10/12 years he presented with 24 hours of vomiting followed by diarrhea and seizures. No aspirin had been given. He was lethargic and stimulation produced asymmetric decorticate posturing. Initial glucose was 28 mg/dl, maximal AST 163 U/L (

Changes of plasma osmolality, chloride concentration and gill Na−K-ATPase activity in tilapia Oreochromis mossambicus (obtained from Tainan Fish Culture Station of Taiwan Fisheries Research Institute, 1987) during seawater acclimation were examined. Three experiments were performed. (1) Freshwater (FW) to 30‰ salinity seawater (SW): plasma osmolality and chloride rose violently immediately post-transfer. At 6 h, gill Na−K-ATPase activity began to increase but most fish died from excessive plasma osmolality and Cl. (2) FW to 20‰ salinity SW: plasma osmolality and chloride increased immediately post-transfer, but more slowly than in (1), and began to decrease at 24 h. However it was not until 12 h post-transfer that gill Na−K-ATPase activity rose slowly. (3) FW to 20‰ salinity SW for 24 h, then to 30‰ salinity SW: after transfer to 30‰ salinity, plasma osmolality and chloride showed only a small increase initially then declined, while gill Na−K-ATPase activity started to rise rapidly within 3 h. The present results coincided with our previous morphological data concerning the ultrastructural responses of gill chloride cells. These are discussed to elucidate the osmoregulation mechanisms in tilapia during seawater acclimation.