Practical use of the statistically modified laminate model for injection moldings. Part 1: Method and verification

The fibers in injection molded FRP provide the material's strength and stiffness; however, they also supply many of the problems. Preferential orientation of fibers during molding can reduce strength and stiffness below expected values in critical directions, or induce warpage in thin walled sections. Makers of short fiber reinforced injection molded products typically use computer aided engineering packages to optimize product performance and manufacturing variables. However, the reliability of the fiber orientation simulation can be limited, and the method is not easily understood, making an assessment of accuracy for a given situation difficult. In addition, the structural module of flow analysis packages is often a basic package with many features missing. This paper presents a structural analysis system for injection molded parts made of short fiber reinforced plastics. A full-featured commercial structural analysis code is interfaced with a flow analysis program using a practical material model that takes into account the effects of local fiber orientation. The system is completely open to the user, and can be modified as required.     

Visual simulation of water currents using a particle-based behavioural model

Several CG researchers have simulated impressive ocean waves so far. Recently, other researchers have succeeded in simulating waterfalls by employing a mass of particles. However, visual simulation of water currents having complex surfaces, such as mountain streams and turbulent water, still remains a challenging problem thanks to their complicated patterns of behaviour. Effective simulation methods for water currents are expected to have abilities to represent the following remarkable behavioural visual features of water: the appearance of a pool, an obstacle avoidance flow, a fluent flow, a flow into an open space, the collision and the confluence of flows and the occurrence of splashes. In this paper, we present a new type of particle-based simulation method for complex water currents which is not based on strict fluid dynamics but rather classified into a ‘quasi-physically-based’ simulation method constructed on the basis of algorithmic approaches. We first present a simple behavioural model of a ‘water-particle’. Next, we propose a method for generating CG images of water currents from a set of water-particles. Finally, we demonstrate the ability of our method by showing several examples of the simulation.     

Characterization of surface-charge-mosaic-modified ultrafiltration membranes prepared by laser-induced surface graft polymerization

Surface-charge-mosaic-modified ultrafiltration membranes with charged domains of various sizes (500, 100, or 50 μm) were prepared by two-step laser-induced surface graft polymerization using a striped photomask. First, the surface of an ultrafiltration membrane was treated with 4-vinylpyridine after laser irradiation using a striped photomask. Subsequently, the striped photomask was shifted and the surface that was initially shaded from the laser beam by the photomask was exposed to laser irradiation and treated with acrylic acid. The surface element distribution, surface chemical structure, and ion-exchange capacities of the treated membrane were determined by scanning X-ray photoelectron spectroscopy (XPS) analysis, time-of-flight secondary ion mass spectrometry (TOF-SIMS) with imaging capacities, and acid–base titration, respectively. Oxygen and carbon distribution maps determined by the scanning XPS analysis and the TOF-SIMS maps for ¹⁶O⁻ and ²⁶CN⁻ ions show that the surface of the treated membrane had striped domains composed of poly(4-vinylpyridine) and poly(acrylic acid). The anion- and cation-exchange capacities of the treated membranes were approximately 2.0 mEq/m². The ultrafiltration rate of these membranes was markedly lower than that of a nontreated ultrafiltration membrane, but increased as the charge domain size decreased. The membrane flux of sodium ions also increased with decreasing charge domain size. This tendency was much stronger for sodium ions than for glucose. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1141–1149, 1998     

Effect of starvation on lipid metabolism and stability of DHA content of lipids in horse mackerel (<Emphasis Type="Italic">Trachurus japonicus</Emphasis>) tissues

For the purpose of characterizing the effect of starvation on 22∶6n−3 (DHA) content in marine fish tissues, horse mackerel (Trachurus japonicus) were reared in a tank containing filtered, sterilized seawater under nonfeeding conditions for 107 d (survival rate of the fish was 96.5%). The crude total lipids (TL) of ordinary dorsal muscle, dorsal skin, and viscera of the starved individuals were separated into classes on silicic acid columns, and the constituents of the TL were quantified by gravimetric recovery from column chromatography. The TL, initially>85% TAG in dorsal muscle, and even more in skin lipids, decreased dramatically within the first 44 d of starvation, and then decreased more gradually during the remainder of the test period, whereas the visceral TL decreased more slowly. The percentages of both saturated and monoenoic FA in the muscle TL also decreased somewhat, but those of DHA increased significantly in muscle during the test periods. Decreases in PE and PC initially were much smaller than TAG, but DHA levels remained high in both PE and PC. These findings indicate that all of the FA in the depot lipids of horse mackerel tissues are easily metabolized for energy production during starvation, but DHA in muscle lipids of the starved fish was maintained at a consistently high level, indicating that starvation did not affect DHA stability in phospholipids. The findings suggest that preservation of DHA in cell membrane lipid PE and PC is necessary for self-protection functions in starving fish.     

Structures and field emission properties of heat-treated C60 fullerene nanowhiskers

The structures and field electron emission properties of C₆₀ fullerene nanowhiskers were investigated. The single crystalline C₆₀ fullerene nanowhiskers were straight, surrounded by facets, and had a uniform submicrometer diameter along the long axis. Heat treatment of the nanowhiskers drastically transformed the inner structure from C₆₀ crystal to glassy carbon, while the outer structure kept its original morphology despite heat treatment. Field electron microscopy images of the heat-treated nanowhiskers showed striped patterns, characteristic of an agglomerate of crumpled graphitic layers.     

A study on hydration behaviors of interlayer cations in montmorillonite by solid state NMR

Solid state ²³Na NMR spectra of Na-montmorillonite under dry and hydrated conditions have been measured to study hydration structure of Na⁺ in interlayer spaces. The ²³Na triple quantum (3Q) MAS NMR experiments have been performed to determine the quadrupole coupling constants (C_Q) and the isotropic chemical shifts (δ_iso). The C_Q values were found to remarkably depend on water content, i.e. the C_Q values increase with changing from dry condition to hydrated one (at around 12.5 wt% water content) and gradually decrease with an increase in the water content. Since the C_Q value is a sensitive parameter to the local structure of the nucleus measured, the changes in C_Q values with water content should correspond to those in the hydration structure of Na^C in the interlayer spaces. Thus, it is considered that the increment of the C_Q value in the water content of 12.5 wt% is due to the formation of hydrated Na⁺ with planner structure, and that the decrease in C_Q values with the water content is attributed to the formation of hydrated Na⁺ with spherical symmetric structure.     

Fire spread phenomena: The role of observation in experiment

Summarized are recent experimental findings of fire spread phenomena. This review covers flame spread over solids (including melting solids and metals), large-scale spread through discrete fuels (such as fire brands and fire whirls), and scale modeling techniques applied to flame spread study. Emphasis is placed on the importance of observation in experiments which is the source of imagination and successful modeling.     

Pixels consisting of a single vertical-cavity laser thyristor and adouble vertical-cavity phototransistor

Bidirectionally cascadable optical pixels that consist of a single-vertical-cavity surface-emitting laser (VCSEL) thyristor and a double-vertical-cavity phototransistor are proposed. Despite almost identical layer structures, each device characteristic can be independently optimized by introducing a λ/2-spacer layer into the phototransistor section. A lasing threshold of 0.8 mA and a slope efficiency of 0.25 W/A are obtained for the laser thyristor, and a flat-topped photocurrent spectrum over 30 A and a photocurrent gain of 70 A/W are obtained for the phototransistor at the resonant wavelength. This work demonstrates the possibility of monolithic integration using thermal desorption and a regrowth technique and the suitability of these devices for massively parallel optical interconnections