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Injection Process (injection + process)
Selected AbstractsFabrication of Gas Electrodes by Wet Powder Spraying of Binder-Free Particle Suspensions Using a Pulse Injection ProcessJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2007Naoki Oishi A process for wet powder spraying of binder-free particle suspensions using pulse injection was devised for the fabrication of gas electrodes. The resulting deposited electrodes were found to have fine and uniformly distributed pores, to have good adhesion, and low interfacial resistance on electrolyte substrates. The uniformity of the layers was improved by decreasing the spray pulse to 0.05 s with a 1-s off period. Even without drying or any pre-treatments before firing, there was no cracking or delamination of the deposited layer. The deposited layer remained porous, crack-free, and well bound to the substrate after firing. [source] A low-leakage sample plug injection scheme for crossform microfluidic capillary electrophoresis devices incorporating a restricted cross-channel intersectionELECTROPHORESIS, Issue 15 2008Chin-Lung Chang Abstract This study develops a crossform CE microfluidic device in which a single-circular barrier or a double-circular barrier is introduced at the cross-channel intersection. Utilizing a conventional crossform injection scheme, it is shown that these barriers reduce sample leakage and deliver a compact sample band into the separation channel, thereby ensuring an enhanced detection performance. A series of numerical and experimental investigations are performed to investigate the effects of the barrier type and the barrier ratio on the flow streamlines within the microchannel and to clarify their respective effects on the sample leakage ratio and sample plug variance during the injection process. The results indicate that a single-circular barrier injector with a barrier ratio greater than 20% and a double-circular barrier injector with a barrier ratio greater than 40% minimize the sample leakage ratio and produce a compact sample plug. As a result, both injectors have an excellent potential for use in high-quality, high-throughput chemical analysis procedures and in many other applications throughout the micro-total analysis systems field. [source] Integration of continuous-flow sampling with microchip electrophoresis using poly(dimethylsiloxane)-based valves in a reversibly sealed deviceELECTROPHORESIS, Issue 14 2007Michelle W. Li Abstract Here we describe a reversibly sealed microchip device that incorporates poly(dimethylsiloxane) (PDMS)-based valves for the rapid injection of analytes from a continuously flowing stream into a channel network for analysis with microchip electrophoresis. The microchip was reversibly sealed to a PDMS-coated glass substrate and microbore tubing was used for the introduction of gas and fluids to the microchip device. Two pneumatic valves were incorporated into the design and actuated on the order of hundreds of milliseconds, allowing analyte from a continuously flowing sampling stream to be injected into an electrophoresis separation channel. The device was characterized in terms of the valve actuation time and pushback voltage. It was also found that the addition of sodium dodecyl sulfate (SDS) to the buffer system greatly increased the reproducibility of the injection scheme and enabled the analysis of amino acids derivatized with naphthalene-2,3-dicarboxaldehyde/cyanide. Results from continuous injections of a 0.39,nL fluorescein plug into the optimized system showed that the injection process was reproducible (RSD of 0.7%, n,=,10). Studies also showed that the device was capable of monitoring off-chip changes in concentration with a device lag time of 90,s. Finally, the ability of the device to rapidly monitor on-chip concentration changes was demonstrated by continually sampling from an analyte plug that was derivatized upstream from the electrophoresis/continuous flow interface. A reversibly sealed device of this type will be useful for the continuous monitoring and analysis of processes that occur either off-chip (such as microdialysis sampling) or on-chip from other integrated functions. [source] Numerical modelling of compensation grouting above shallow tunnelsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 5 2005C. Wisser Abstract This paper describes the development of a numerical model for compensation grouting which is a useful technique for the protection of surface structures from the potentially damaging movements arising from tunnel construction. Pipes are inserted into the ground between the tunnel and the overlaying structure from an access shaft. Buildings on the surface are instrumented and movements are carefully monitored. Once the deformations exceed a certain Trigger Level, grout is injected into the ground to prevent damage. In the finite element model described here, compensation grouting is modelled by applying an internal pressure to zero-thickness interface elements embedded in the mesh. An ,observational algorithm' is used, where the deformations of the surface are monitored and used to control the injection process. Example analyses of compensation grouting are given for three-dimensional tunnel construction underneath a greenfield site. Different strategies are used to control the injection process and their effectiveness in preventing surface movement is assessed. The numerical model is shown to replicate general behaviour expected in the field and is capable of modelling the control of ground surface movements at a greenfield site. Copyright © 2005 John Wiley & Sons, Ltd. [source] Numerical simulation of gaseous fuel injection: A new methodology for multi-dimensional modellingINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 6 2010Luca Andreassi Abstract The use of natural gas (instead of liquid or solid fuels) is nowadays drawing an increasing interest in many applications (gas turbines, boilers, internal combustion engines), because of the greater attention to environmental issues. To facilitate the development of these applications, computer models are being developed to simulate gaseous injection, air entrainment and the ensuing combustion. This paper introduces a new method for modelling the injection process of gaseous fuels that aims to hold down grid requirements in order to allow the simulation also of other phenomena, like combustion or valve and piston motion, in reciprocating internal combustion engines. After a short overview of existing models, the transient jet model and the evaluation of inflow conditions are described in detail. Then a basic study of the grid effects on the jet evolution is presented. The model is updated and validated by comparing numerical results with available experimental data for two different operating conditions: a subsonic and a supersonic under-expanded case. The model demonstrates to be fast enough to be used in a multi-dimensional code and accurate enough to follow the real gas jet evolution. Copyright © 2009 John Wiley & Sons, Ltd. [source] Morphological analysis of the tiger stripe on injection molding of polypropylene/ethylene-propylene rubber/talc blends dependent on based polypropylene designJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Koki Hirano Abstract Tiger stripe of injection molding of polypropylene (PP)/elastomer/talc blends was analyzed in terms of the morphology of the dispersed phase comprising elastomer components by using gloss and scanning electron microscopy (SEM). In addition, the contribution of the polymer design of PP, i.e., industrial block-type grade consisting of a homo-PP portion as the matrix and an ethylene propylene random copolymer portion as the domain is discussed. Local gloss measurement of the injected specimen along with the flow direction of the molten blends indicates a periodic fluctuation repeating higher and lower degrees of gloss, corresponding to the period of glossy and cloudy portions of the tiger stripe, respectively. These local gloss degrees are highly dependent on the morphologies of the dispersed phases near the surface layer of the injected specimen. The gloss increases when the ratio long axis (L) and diameter (D), L/D, of the dispersed phase are increased, and the gloss decreases when the L/D is decreased. Increasing the intrinsic viscosity of the ethylene-propylene rubber portion of the PP is an effective design factor for restricting the deformation against shear strain during injection process by giving the dispersed phases high elasticity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 192,199, 2007 [source] Adhesion control for injection overmolding of polypropylene with elastomeric ethylene copolymersPOLYMER ENGINEERING & SCIENCE, Issue 10 2009Marco Dondero Two types of random semicrystalline copolymers (ethylene,octene and ethylene,butene) were overmolded on a core polypropylene. Maximum solid,liquid interface temperature achieved for the overmolding injection process is used as the key parameter for adhesion control. The main bonding process is shown to be a Rouse-type fingering mechanism that develops in short time scales. Normalized peel tests were conducted on overmolded samples to measure the resulting polypropylene copolymers' bonding strength. All the ethylene random copolymers used for this study give good adhesion to polypropylene in overmolding processes, provided the right range of interface temperature is reached. Adhesion strength can be easily controlled for efficient debonding and recycling of used overmolded parts. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source] A robust shock and noise model for the manufacturing of molded LDPE foamsPOLYMER ENGINEERING & SCIENCE, Issue 12 2008S. Chedly The article concerns the injection manufacturing process of molded foam sheets and their intrinsic shock and noise performances. The main goal is to optimize the physical performances of molded plastic foams at an early stage in their design and manufacturing. The effects of injection process parameters on the properties of molded LDPE foams are investigated. The input optimization parameters considered are: injection temperature, mold temperature, injection speed, plasticization back pressure, and screw rotation speed during the plasticization phase. The output optimization parameters considered are: density, shock absorption, and acoustic absorption. The experimental design method made use of the Taguchi table and central composition design. This allows us to identify simplified mathematical models for input/output and to detect the most influential input in the injection process. We conclude by validating the models and their robustness. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] An inverse estimation of initial temperature profile in a polymer processPOLYMER ENGINEERING & SCIENCE, Issue 1 2008Ali A. Ranjbar Since one of the most important parameter in polymer processing such as injection stretch blow molding is temperature distribution in the thickness direction, an inverse method has been applied to estimate this profile. This process comprises of four steps. In the first step the preform is injection molded, and in the second and third step it is stretched by a rod to its final length and then inflated and in the last step it is discharged from the mold. In such kind of polymer flows viscous dissipation plays a remarkable role in the evolution of temperature profile. Some theoretical temperature profile has been applied to confirm the validation of the inverse algorithm. Different solution techniques are applied in this article to the inverse problem under consideration, namely: the conjugate gradient and Levenberg,Marquardt method. After the preform is injection molded, which is the first step, it is removed from the mold, which corresponds to time t = 0. At this moment an infrared camera is used to record the surface temperature of the preform with a certain time step. With regard to variation of thermal properties with temperature, the inverse problem becomes nonlinear. These experimental data provided by the infrared camera are then used to estimate the temperature profile at the end of injection process before stretching and inflation took place. POLYM. ENG. SCI., 48:133,140, 2008. © 2007 Society of Plastics Engineers [source] Biocomposites based on Alfa fibers and starch-based biopolymerPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 12 2009R. Belhassen Abstract Biocomposite materials based on Alfa cellulose fibers (esparto grass plant) as reinforcing element and starch-based biopolymer matrix were prepared and characterized in terms of mechanical performance, thermal properties, and water absorbance behavior. The fibers and the matrix were first mixed in the melted state under mechanical shearing using a plastograph and the obtained composites were molded by injection process. The tensile mechanical analysis showed a linear increase of the composite flexural and tensile modulus upon increasing the fiber content, together with a sharp decrease of the elongation at break. The fibers, incorporation into the biopolymer matrix brings about an enhancement in the mechanical strength and the impact strength of the composite. Dynamic mechanical thermal analysis (DMTA) investigation showed two relaxations occurring at about ,30 and 35°C. The addition of Alfa fibers enhanced the storage modulus E, before and after T,, which is consistent with the reinforcing effect of Alfa cellulose fibers. Copyright © 2008 John Wiley & Sons, Ltd. [source] Hyaluronic acid filler injections with a 31-gauge insulin syringeAUSTRALASIAN JOURNAL OF DERMATOLOGY, Issue 1 2010Adrian C Lim ABSTRACT Hyaluronic acid gel is a commonly used skin/soft tissue filler in cosmetic dermatology. Hyaluronic acid fillers are packaged in proprietary luer-lock syringes that can be injected via a 30-gauge, 27-gauge or larger diameter needle depending on the consistency of the gel. A method of decanting proprietary hyaluronic acid fillers into multiple 31-gauge insulin syringes for injection is described. The use of a 31-gauge insulin syringe for filler injections can potentially enhance the injection process through more accurate product delivery and placement. This has the potential to produce a more balanced and symmetrical outcome for patients. Additional benefits include less injection pain, less bleeding/bruising and higher levels of patient satisfaction. [source] Aqueous and petroleum fluid flow associated with sand injectitesBASIN RESEARCH, Issue 2 2005Rene Jonk Field, petrographic and fluid inclusion characteristics of sand injectites from five outcrop localities and from the subsurface of the Tertiary of the south Viking Graben are described. Although the case studies are from a wide variety of sedimentological, stratigraphic and tectonic settings, and hence their diagenetic evolutions differ significantly, it is possible and useful to assign diagenetic events to three distinct phases of fluid flow associated with sand injectites in sedimentary basins. Firstly, there is fluid flow associated with the injection of the fluid,sediment mix during shallow burial. Early diagenetic imprints in sand injectites reveal that basinal fluids, which may be released during movement along deeper-seated faults, can be associated with this process and thus the injection process may reveal information on the timing of basin-scale movement of fluids. Secondly, following the injection process, basinal fluids continue to migrate through uncemented injectites and mix with the ambient meteoric and/or marine pore fluids that invade injectites from the overlying and surrounding host sediments. Early, often pervasive, carbonate cementation is common within sand injectites and rapidly turns sand injectites into flow barriers during shallow (<1 km) burial. If early carbonate cementation is not pervasive, fluid inclusions in late quartz cement (,>2 km of burial) reveal additional information on fluid flow associated with sand injectites during deeper burial. The latest phase of fluid flow occurs when sand injectites are reactivated as preferential fluid conduits during phases of deformation, when well-cemented subvertical sand injectites become sites of focussed brittle deformation (fracturing). This study shows that sand injectites are a common and volumetrically important type of structural heterogeneity in sedimentary basins and that long-lived fluid flow associated with sand injectites in very different settings can be assessed and compared systematically using a combination of petrography and fluid inclusion studies. [source] Groutability of cement-based grout with consideration of viscosity and filtration phenomenonINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 16 2009Jong-Sun Kim Abstract The groutability depends on the properties of the grout, its injection processes, and on the mechanical properties of the soil formation. During the process of pouring cement-based grouting into a porous medium, a variation with time occurs in the viscosity of grout suspension. In addition, the particle filtration phenomenon will limit the expansion of the grouted zone because cement particles are progressively stagnant within the soil matrix. In this paper, a closed-form solution was derived by implementing the mass balance equations and the generalized phenomenological filtration law, which can be used to evaluate the deposition of cement-based grout in the soil matrix. The closed-form solution relevant to a particular spherical flow was modified by a step-wise numerical calculation, considering the variable viscosity caused by a chemical reaction, and the decrease in porosity resulting from grout particle deposition in the soil pores. A series of pilot-scale chamber injection tests was performed to verify that the developed step-wise numerical calculation is able to evaluate the injectable volume of grout and the deposition of grout particles. The results of the chamber injection tests concurred well with that of the step-wise numerical calculation. Based on the filtration phenomenon, a viable approach for estimating the groutability of cement-based grout in a porous medium was also suggested, which might facilitate a new insight in the design of the grouting process. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||