Abstract An improved vacuum infusion (VI) process, called dynamic pressure molding (DPM), has been proposed to reduce void formation during infusion. In this method, the conventional VARTM process is modified by mounting a rigid chamber on top of mold. The compaction bag and are independently dynamically controlled achieve optimal impregnation for avoiding formation. To postinfusion time, premature sealing inlet, heated air compression, two-sided drainage also used in DPM. Two different...

The pre-compacted preform vacuum infusion (PPVI) is a variation of the vacuum-assisted resin transfer molding (VARTM) process. technology additionally leverages elasticity bag during infusion, enabling pressure to exceed one atmospheric and thereby reducing time. PPVI effectively reduces total filling time waste through use partial strategy two-sided drainage. effects four process parameters, including spring modulus bag, pressure, strategy, characteristics, on are investigated. Numerical...

We have investigated photoexcited carrier lifetimes in arsenic-ion-implanted semi-insulating GaAs by time-resolved reflectivity measurements. Subpicosecond (220 to 550 fs) which do not exhibit apparent dosage dependence for samples bombarded with 200 keV arsenic ions at increasing dosages the range of 1012 and 1016 ions/cm2 are reported. The shortest lifetime was observed sample irradiated 1013 ions/cm−2. These ever ion-damaged comparable those low-temperature molecular beam epitaxially...

ABSTRACT THE bulk thermal conductivities of wheat, corn, and grain sorghum were determined at ambient temperature by the line heat source method. The moisture contents samples ranged from 11 to 18% (w.b.), densities 700 880 kg/m^ depending on type grain. Under those conditions 0.181 0.202 W/m-K for hard red winter 0.167 0.190 soft 0.162 0.186 corn 0.160 0.184 sorghum. At a constant content, conductivity each increased linearly with density. given density, content.

The results of an experimental study two-phase heat dissipation in high-conductivity porous channel sinks are presented. Porous channels various sizes were fabricated using sintered copper particles inside rectangular with base dimensions 25 mm by mm, either 3 or 10 height. experiments conducted subcooled water as the working fluid and test conditions ranged from inlet temperature 85 to 95°C, pressures 1.062 1.219 bars, flow rates 22.5 150 ml/min, fluxes W/cm2. compared predicted a...

Abstract Presented are the results of a heat transfer analysis two-phase dissipation using high-conductivity porous-channel sink. In analysis, consistent set conservation equations based on phase-averaged properties fluid derived from conventional ones and solved numerically by finite volume method. The indicate that high conductivity large solid-fluid contact area porous channel result in performance for dissipation, which may be an alternative to cooling techniques microelectronics with...

Two, 6.6-m-diameter steel bins were used to store wheat for observing seasonal grain temperature variations. Aeration in one bin was controlled by a programmable microprocessor and the second bin, it manually with limit settings. In each 132 thermocouples installed measure temperatures of at different depths radial distances from center. Temperatures wall, floor, air above surface also measured. recorded daily using data acquisition system. Each filled 99.3 t Hard Red Winter Wheat depth 3.66...

Compression resin transfer molding (CRTM), combining (RTM) and compression molding, have been developed to fabricate fiber reinforced plastic (FRP) components with large dimensions or high volume content. Although a lot of literature on CRTM is available, relatively little useful technical information present regarding the proper choice conditions for component optimization. The objective this research investigate effects process variables, including injection pressure, mold opening...

Vacuum-assisted compression resin transfer molding, a flexible molding process, has been developed to reduce cycling period in the present study. The vacuum-assisted utilizes an extra elastic film placed between upper mold and cavity compared with molding. Through stretchable film, state of fabric stack is under control. During injection, loose fiber then easily introduced into cavity. Once enough amount injected, pressure applied on that compacts preform drives through preform. Prior...

In the present article, an open gap is between fibrous reinforcements and upper mold during filling stage of resin injection/compression molding (I/CM). Thus can quickly fill up gap. After that, platens are brought together drive through preform. The motion in simplified using Hele-Shaw flow model, while Darcy’s law used to calculate fields fiber mats. numerical simulation based on body-fitted finite element method (FEM). Results show that injection time short most elevated closing cavity...

Abstract Vännman (1995 , K. ( 1995 ). A unified approach to capability indices . Statistica Sinica 5 : 805 – 820 .[Web of Science ®] [Google Scholar]) proposed a superstructure Cp (u, v) for processes with normal distributions, which include Cp, Cpk, Cpm, and Cpmk as special cases. Pearn Chen (1997 W. L. S. 1997 Capability non distributions an application in electrolytic capacitor manufacturing Microelectronics Reliability 37 12 ): 1853 1858 .[Crossref], [Web considered generalization v),...

ABSTRACT THE bulk thermal conductivity and specific heat of wheat, grain sorghum, corn dusts were deter-mined at ambient temperature by the line source method. The moisture contents dust samples rang-ed from 8.8 to 17 percent (w.b.), densities 240 580 kg/m3. Under those conditions ther-mal conductivities ranged 0.062 0.074 W/(m-C) for wheat dust, 0.080 0.092 sorghum 0.086 0.101 dust. Specific 1900 2200 J/(kg*C) all three types con-ductivity each type increased linearly with content density. content.

ABSTRACTA self-propelled 4-trough grain spreader developed at the U.S. Grain Marketing Research Laboratory and a commercial 2-trough were used to fill bins with corn. Their use significantly improved uniformity of fine material distribution in mass but increased dustiness air bin. The bulk density airflow resistance corn bin filled spreaders higher than those values for without spreader. surface was more level when or damage caused by not different from that observed no used.

Two 6.6-m-diameter steel bins filled with 99.3 t of Hard Red Winter wheat were used for observing seasonal grain temperature and moisture content variations. Aeration in one bin was controlled manually limit settings. the second by a programmable microprocessor using ambient air humidity as control parameters. A model developed to predict its distribution within mass during storage. The based on two-dimensional transfer equation associated boundary conditions solved finite difference method...

Thin-wall gas assisted injection molding of thermoplastics has become an important process in industry because its light weight, relatively lower resin cost per part, and faster cycle time. This report is devoted to investigate the effects different processing parameters on length penetration thin-wall molded parts. The first part this find ways optimize An L'18 experimental matrix design based Taguchi method was conducted that affect second identify relative significance each parameter...

ABSTRACT A self-propelled rotational 4-trough grain spreader constructed at the U.S. Grain Marketing Research Laboratory and two commercially available type spreaders were used to fill a 6.4-m diameter bin with wheat, corn, sorghum. The for filling was choke-fed through an orifice spreaders. Under this operating condition, uniformity of fine material distribution in mass generally same bins filled or without spreader. Damage during lower when it than transferred conventional spout. When...

Abstract The operating conditions of a turbulent contact absorber (TCA) can be divided into four regimes. characteristic behaviour TCA in each the regimes is discussed. condition below flooding point usual regime. Correlations are developed to relate pressure drop and liquid holdup by variables. A terminal velocity model explain TCA. With this model, hydrodynamic behavior at identified. total across single stage distinguished clarify controversy whether gas affect composed due distributor...

A model has been developed for the transverse impregnation of resin into a continuous unidirectional packed fiber bundles. The takes account two types flow, namely macro-flow around bundles and micro-flow fibers in bundles, occurring simultaneously. Both flows are described by Darcy's law. Results show that an elliptic type void is formed within bundle under certain circumstances. will soon shrink to nothing if vacuum assistance applied mold, while it mobilized compressed not mold. By...

The compression resin transfer molding (CRTM) filling process involves two stages: the injection phase and phase. Two modes are considered — constant volumetric flow rate pressure while velocity is utilized in this study. Three typical cases used to investigate initiation effects on process. When inlet condition a rate, numerical results show that has both increase decrease pressure. Thus, discontinuity present at onset or end of compression. Among three CRTM cases, with simultaneous...

Abstract A variant process incorporating the method of bag compression into resin transfer molding (RTM), called vacuum assisted RTM (VACRTM), has been developed to reduce cycling period and improve quality part. The utilizes a flexible placed between upper mold preform compared with RTM. By controlling stretchable bag, is easily introduced cavity filled loose preform. Then, ambient pressure applied on that compacts drives through remaining dry objective this research explore simplified...

This article presents a predictive control methodology for the precise tracking of complex reference commands in dual-stage actuator systems. To improve synchronized motion performance, cost function was applied to account error as well first-stage actuator. The system uses repetitive model with two controllers reduce occurrence periodic errors. As precision machining, trajectory containing dynamic signals non-trivial magnitude and frequency orders motor/piezoelectric-driven used evaluate...