Combination Of Process Conditions Research Articles

Modeling the Ultrasonic Micro-Injection Molding Process Using the Buckingham Pi Theorem.

Dimensional analysis through the Buckingham Pi theorem was confirmed as an efficient mathematical tool to model the otherwise non-linear high order ultrasonic micro-injection molding process (UMIM). Several combinations of processing conditions were evaluated to obtain experimental measurements and validate the derived equations. UMIM processing parameters, output variable energy consumption, and final specimen's Young modulus were arranged in dimensionless groups and formulated as functional relationships, which lead to dimensionless equations that predict output variables as a function of the user-specified processing parameters and known material properties.

Dispersion strengthening of copper by internal oxidation of rapidly solidified Cu-RE alloys

Abstract Combination of rapid solidification and internal oxidation was used for producing a fine dispersion of rare earth oxide particles in the copper matrix. An overall microstructural analysis has shown that the internal oxidation temperature, the rapidly solidified microstructure and its changing ahead of the internal oxidation front strongly influence the mechanism of the internal oxidation process and the resulting microstructure. The internal oxidation in a Cu –Yb alloy took place mainly by direct oxidation of intermetallic particles. Contrary to this, in a Cu – Er alloy two mechanisms of internal oxidation have been clearly observed: (i) Dissolution of intermetallic particles ahead of the internal oxidation front and oxidation of the erbium from the solid solution and (ii) direct oxidation of the Cu–Er intermetallic particles. While a reasonable optimum combination of processing conditions at internal oxidation in the solid state, yielding suitable oxide dispersions, seems to have been identified for the Cu–Er alloy, the same was not true for the Cu–Yb alloy. However, the internal oxidation of the Cu–Yb alloy in the semisolid state, which occurs by alternation of two processes – Yb oxides precipitation and Cu matrix solidification – led to a relatively uniform dispersion of Yb oxide particles.

Food-grade hydroxypropyl methylcellulose-based formulations for electrohydrodynamic processing: Part I – Role of solution parameters on fibre and particle production

Electrohydrodynamic (EHD) processing allows the production of micro and nano structures with high surface-area-to-volume ratio from biopolymers and environmentally friendly solvents. Such structures hold a very significant potential for application in the food area. The aim of this work was to assess the role of solution parameters in the formation of hydroxypropyl methylcellulose (HPMC)-based micro and nanostructures through EHD processing, establishing a relationship between variables such as viscosity and concentration, and processing zones (i.e., combinations of processing conditions that move the system towards electrospinning – fibres are formed – or electrospraying – particles are formed).Micro and nano structures were produced through electrospinning and electrospraying using HPMC with low (HPMC LMW) and high (HPMC HMW) molecular weight. Solutions were characterized regarding surface tension, conductivity, viscosity, zero-shear rate and specific viscosity. Plotting specific viscosity versus concentration allowed determining the electrospraying and electrospinning zones, which were confirmed through scanning electron microscopy analysis. HPMC LMW led to the formation of particles. For concentrations between 1 and 2% (w/v) rod like particles were formed, and round particles were obtained for concentrations ranging from 3 to 6% (w/v). The mean particle diameter varied between 833 and 1188 nm, while the aspect ratio ranged from 1.3 to 3.7. Nanofibres were generated using HPMC HMW, being beaded fibres produced at a concentration of 1% (w/v) and smooth fibres produced for concentrations between 1.5 and 2.25% (w/v). The developed nanofibres displayed a mean diameter ranging between 79 and 161 nm.Electrospraying and electrospinning zones were successfully determined for HPMC LMW and HMW. Nevertheless, near transition zones variability regarding the obtained morphology was observed once other processing parameters (e.g., flow rate) can influence the morphology of fibers and particles.

Nanostructural evolution in vapor deposited phase-separating binary alloy films of non-equimolar compositions: Insights from a 3D phase-field approach

A rich variety of self-organized nanoscale patterns evolve during physical vapor deposition of phase-separating alloy films. However, our limited understanding of the fundamental mechanisms of morphological evolution during the vapor deposition of multi-component metallic films is a major hurdle in optimizing their mechanical and functional properties. Diffuse interface approaches, such as the phase-field method, can enable the prediction of nanostructured morphologies in a broad class of immiscible binary alloys by achieving a fundamental understanding of self-assembly mechanisms down to the nanometer scale. Here, we adopt a three-dimensional phase-field approach to numerically investigate the role of alloy compositions, deposition rates, and temperature on the morphological self-assembly of nanostructures in vapor deposited alloy films. We explain the influence of alloy composition and deposition parameters on the evolution of novel film morphologies such as perforated layered and aligned rods. Following an extensive parametric study, we construct morphology maps that help expand our knowledge of the different combinations of processing conditions that generate distinct nanoscaled morphologies. Finally, we expand and elucidate a theory based on the minimization of interfacial energy that underpins the mechanisms of morphological transitions in vapor deposition of immiscible alloy films for an entire composition range.

A Novel Integrative Processing Technology for the Preparation of Rehmanniae Radix Slices.

The traditional processing method for the slices preparation of Rehmanniae roots is time- and energy-consuming and is prone to result in loss of active components during twice water-treatment (once for wash and the other for softening) and drying steps. In this study, we firstly explored an integrative processing technique for Rehmanniae Radix by 2x3 factorial experiment based on the contents of catalpol and verbascoside as measured by HPLC. The potential differences between the traditional stepwise processing technique and the integrative processing technique for catalpol and verbascoside in the prepared slices were investigated. To further confirm the effectiveness of drugs using the integrative processing technique, some pharmacological variables, such as rectal temperature, hematologic parameters (RBC, HGB, HCT, and blood viscosity), and coagulation parameters (TT, APTT, PT and FIB), were detected in a blood-heat and hemorrhage syndrome rat model. Two-way ANOVA analysis showed that drying for 18 h at 50°C was considered as the best combination of process conditions. The mean catalpol and verbascoside contents in the integrative method-processed samples (4.30% and 0.33%, respectively) were higher than those in the traditional method-processed samples (2.61% and 0.21%, respectively). Significant increases in rectal temperature, and hematologic parameters, TT, APTT, and FIB, were observed in the model group rats, compared to the blank group animals (P<0.01). Both in the integrative groups and traditional groups, the extracts caused significant decreases in rectal temperature, RBC, HGB, and HCT with increased concentration compared to the model group animals. All coagulation parameters tested were shortened in model rats received two kind prepared slices. There were no significant therapeutic differences between the integrative and the traditional method-processed slices on the hemostasis and hemorheological parameters in this blood-heat and hemorrhage syndrome rat model, indicating that our integrative method may be a feasible technique for processing Rehmanniae Radix slices.

Optimization of pH, temperature and CaCl2 concentrations for Ricotta cheese production from Buffalo cheese whey using Response Surface Methodology

The recovery of milk constituents from cheese whey is affected by various processing conditions followed during production of Ricotta cheese. The objective of the present investigation was to optimize the temperature (60-90 °C), pH (3-7) and CaCl2 concentration (2·0-6·0 mm) for maximum yield/recovery of milk constituents. The research work was carried out in two phases. In 1st phase, the influence of these processing conditions was evaluated through 20 experiments formulated by central composite design (CCD) keeping the yield as response factor. The results obtained from these experiments were used to optimize processing conditions for maximum yield using response surface methodology (RSM). The three best combinations of processing conditions (90 °C, pH 7, CaCl2 6 mm), (100 °C, pH 5, CaCl2 4 mm) and (75 °C, pH 8·4, CaCl2 4 mm) were exploited in the next phase for Ricotta cheese production from a mixture of Buffalo cheese whey and skim milk (9 : 1) to determine the influence of optimized conditions on the cheese composition. Ricotta cheeses were analyzed for various physicochemical (moisture, fat, protein, lactose, total solids, pH and acidity indicated) parameters during storage of 60 d at 4 ± 2 °C after every 15 d interval. Ricotta cheese prepared at 90 °C, pH 7 and CaCl2 6 mm exhibited the highest cheese yield, proteins and total solids, while high fat content was recorded for cheese processed at 100 °C, pH 5 and 4 mm CaCl2 concentration. A significant storage-related increase in acidity and NPN was recorded for all cheese samples.

Process control model for growth rate of molecular beam epitaxy of MgO (111) nanoscale thin films on 6H-SiC (0001) substrates

Magnesium oxide (MgO) is a good candidate for an interface layer in multifunctional metal-oxide nanoscale thin-film heterostructures due to its high breakdown field and compatibility with complex oxides through O bonding. In this research, molecular beam epitaxy (MBE) is used to deposit 10 nm to 15 nm MgO single-crystal films on silicon carbide with hexagonal polytype 6H (6H-SiC) to serve as an interface layer for effective integration of functional oxides. In this work, the effect of MBE process control variables on the growth rate of the MgO film measured in nanometers per minute is investigated. Experiments are conducted at various process conditions and the resulting MgO film growth rate at each combination of process conditions is measured. The process control variables studied are the substrate temperature (100 °C – 300 °C), magnesium source temperature (328 °C – 350 °C), plasma intensity (0 mV – 550 mV), and percentage oxygen on the starting surface of 6H-SiC substrate (9 % – 13 %) after the substrate is prepared by high-temperature hydrogen etching. The film thickness is computed using the effective attenuation length (EAL) of silicon photoelectron peak intensity as measured by x-ray photoelectron spectroscopy (XPS). The film thickness is converted to growth rate by dividing it with the duration of film growth. Using the experimental data, a neural network model is developed to estimate growth rate for any given process variable combination. From this neural network model, multiple replications of data were generated to conduct a 3-level full factorial design of experiments and response surface-based analysis. The study reveals that the plasma intensity has the most significant influence on growth rate. The results indicate that growth rate is relatively low on high-quality substrates with √3 × √3 R30° reconstructed 6H-SiC (0001) surface with optimum oxygen content (approximately 10 %); in contrast, the growth rate is relatively high on substrates with high surface roughness and excessive oxygen on the starting substrate surface.

Wear of disc mill hammer in wet grinding processes on groundnut cake for fish feed production

There is need to determine the wear rates of disc mill hammer used for grinding groundnut cake, a major plant protein in fish feed. This surface wear damage characterised by scoring, cutting, deep grooving and gouging on a metal surface leads to high costs of production. The hammer wear rate was carried out using disc mill for different combinations of processing conditions: disc speed of 2,175, 3,900 and 4,350 rpm; screen size of 1.0, 2.0 and 3.0 mm; moisture contents of 12, 14 and 16% w.b. at 300 operating hours. Response Surface Method was used to optimize the operating variables. The wear rate was found to increase as the moisture content of the groundnut cake decreased. Quadratic models developed for the four responses (tip length loss, width loss, thickness loss and absolute mass) studied indicated the optimum conditions at disc speed 3,262.50 rpm, screen size 2.0 mm and moisture content 14% w.b. The study established that experimental data and model predictions agreed well.

Production of arabinoxylan-oligosaccharide mixtures of varying composition from rye bran by a combination of process conditions and type of xylanase

The aim was to study arabinoxylan-oligosaccharide production from rye bran using heat pretreatment and enzymatic hydrolysis. Due to the potential application in foods, the purity of arabinoxylan was also assessed. Rye bran was heat pretreated to improve xylanase-catalyzed hydrolysis of arabinoxylan into arabinoxylan-oligosaccharides. Enzymatic removal of starch and proteins before or after heat pretreatment increased the purity, although at lower yield. The most attractive process resulted in 62% (w/w) arabinoxylan content after ethanol precipitation. Using xylanases from two glycoside hydrolase families (RmXyn10A from GH10 and Pentopan Mono BG from GH11), different mixtures of unsubstituted and arabinose-substituted xylooligosaccharides were produced. GH10 gave a higher yield of short oligosaccharides (60%w/w) with xylobiose as the main product; xylobiose and xylotriose were the main products with GH11 (40%w/w). Thus, heat pretreatment combined with enzymatic hydrolysis can be used to produce arabinoxylan-oligosaccharides from rye bran that are potentially useful in functional foods.

Shelf life stability of lactobacilli encapsulated in raspberry powder: Insights into non-dairy probiotics

Aim: Study the shelf-life quality changes in raspberry juice with encapsulated lactobacilli (Lactobacillus rhamnosus NRRL B-4495 and Lactobacillus acidophilus NRRL B-442) obtained by spray drying and understand the various factors involved. Methods and results: Raspberry powder was obtained from spray drying lactobacilli and raspberry juice with maltodextrin as an additive. Shelf life of the powder was analyzed over a period of 30 d. Acid and bile tolerance and antibiotic resistance was compared before and after spray drying. Water activity, survival, and scanning electron microscope images were also measured during the shelf life. Conclusions and significance: A combination of processing conditions: inlet temperature (°C), maltodextrin to juice solids ratio and inlet feed rate (ml/min) during spray drying had a significant role on the survival of lactobacilli during shelf life. Refrigerated storage provided a higher shelf-life stability with regards to CFU/g (as high as 84% on day 0 and 98% retention by the end of 30 d) compared to room temperature storage. Probiotic properties during shelf life are affected by the processing conditions and encapsulated food matrix. Thus, understanding these aspects in vitro during shelf life gives us a brief insight into the future of non-dairy probiotics.

Precision Piercing and Blanking of Ultrahigh-strength Steel Sheets

The paper proposes new technologies able to improve the surface quality of sheared products by means of a combined process of finish blanking and press shaving applied to materials having very high strength. Experimental researches were developed and the best combination of process conditions was identified. Furthermore, the technology was checked of so-called delayed fracture properties of the products by subjecting them into a solution of hydrochloric acid. They also have proved to possess good anti-delayed fracture properties.

Press-Shaving Characteristics of Ultrahigh-Strength Steel Sheets

The paper proposes new technologies able to improve the surface quality in the case of press-shaving applied to very high strength materials. Experimental researches were developed and the best combination of process conditions was identified.

Optimum process conditions on shrinkage of an injected-molded part of DVD-ROM cover using Taguchi robust method

Plastic injection molding is an important process to produce thin-shell parts. However, the difficulty in adjusting optimum process conditions may cause defects of the injected-molded parts such as shrinkage. This study investigates on the optimum combinations of process conditions on shrinkage of an injected-molded part of the DVD-ROM cover based on Taguchi method. In doing this, a series of Moldflow analyses have been performed as per L27 orthogonal array design with each analysis by means of the process conditions of mold temperature, melt temperature, injection pressure, injection time, and cooling time. In the meantime, signal-to-noise (S/N) ratio is utilized to determine the optimum combinations of the process conditions for shrinkage through analysis of variance (ANOVA). ANOVA is further used to find which of the process conditions are statistically significant. Finally, confirmation tests at the optimum combinations of the process conditions were executed to verify the robustness and the effectiveness of Taguchi method within 95% confidence interval. From the findings, it can be stated that Taguchi method is a powerful tool for evaluating the defect of shrinkage in the plastic injection molding.

Reaction scheme of o-xylene oxidation on vanadia catalyst

The oxidation of o-xylene (OX) to phthalic anhydride (PA) is one of the important industrial processes based on selective oxidation reactions. However, the fundamental understanding of the by-product formation is still an open task. By using a sample port pilot plant, a detailed investigation was conducted for the first time of the by-product formation at different operation conditions. Several hitherto unknown intermediates could unambiguously be identified. The combination of process conditions and by-product formation enables the discussion of a new improved reaction scheme for the catalytic oxidation of o-xylene. The reaction path from OX to PA is commonly described by a rake mechanism consisting of a number of parallel and serial reactions. Tolualdehyde and phthalide are seen as the main intermediates. The most important by-products are maleic anhydride (MA), CO and CO 2. The reaction paths towards these by-products are widely unknown. Several gas phase components, such as toluquinone and 2,3-dimethyl-p-benzoquinone not reported yet in the current literature, were observed for the first time in this study. Most of these previously unknown components are reaction intermediates, which later do not form the desired reaction product, PA.

Predictive analysis of combined burner parameter effects on oxy-fuel flames

The present paper aims at studying the influence of burner parameters with a separated-jet configuration, namely nozzles diameters and separation distance between the jets, on the flame characteristics (lift-off positions of flame and flame length). The experimental layout considers the use of OH-chemiluminescence to measure the flame characteristics for different combinations of processing conditions. The predictive analysis is based on a neural computation that considers the correlations between the inputs and the outputs of a combustion system using a configuration of separated jet. The predictive analysis shows that a good agreement is found between numerical and experimental results in the case where the predictions are within the process window. The exploration of other process parameter combinations beyond that window gives less convincing results. This is mainly attributed to the fact that steady state characteristics are predicted numerically whereas it is expected experimentally that some of the burner parameter combinations can lead to an increase of the parameters characterizing the flame.

High Pressure Inactivation Kinetics of a Thermomyces lanuginosus Xylanase Evaluated as a Process Indicator

The potential use of Thermomyces lanuginosus xylanase to develop a pressure-temperature-time integrator (PTTI) for high pressure processing was investigated. The combined effect of pressure and temperature on the inactivation of xylanase was studied in the pressure range of 100 to 600 MPa and temperature range of 50 to 70 degrees C. A synergistic effect of pressure and temperature was observed. Xylanase inactivation at the studied processing conditions followed first-order kinetics and was found to be very sensitive to changes in pressure and temperature. The values of activation energy and activation volume were estimated as 92.8 kJ/mol and -23.3 mL/mol at a reference pressure of 450 MPa and a reference temperature of 60 degrees C, respectively. A mathematical model of xylanase inactivation, having as variables time, pressure, and temperature allows the calculation of remaining enzyme activity at any combination of processing conditions within the studied domain. Practical Application: To ensure the optimization and control of high pressure processing, evaluation of the process impact on both safety and quality attributes of foods is essential. Enzymes can serve as effective tools in evaluating the impact of high pressure processes of foods.

Extrusion Effects with Bactericidal Additives in Polymer Wood Composites

Abstract Wood polymer composite is an important material class for industries. Microbiological properties can be an important aspect to enlarge its application base. The biocidal properties of wood polymer composite (WPC) can be aggregated by incorporation of biocidal additives on its composition. But, an important aspect is the evaluation the influence of the fabrication process on its biocidal properties. In particular, the temperature and screw velocity are important parameters for extrusion processes, and the mass proportions of the compounds are important factors to define the WPC properties. Different combinations of process conditions and mass proportions of the composite can promote variation in the magnitude of the bactericidal effect. The bactericidal properties are aggregated in the composite by organic bactericidal additive and the high temperature and high shear rate during the extrusion process can affect the effectiveness of the bactericidal additive function. This paper investigates the effects of the extrusion process parameters associated with different percentages of bactericidal additives on the WPC. The results showed significant effects on the bactericidal properties that depended only on the bactericidal content.

Die Pressure Losses During Injection Molding of Rubber Mixes

Abstract In order to fill the mold in a rubber injection molding process, it is necessary to inject the material into the closed mold. Rubber is usually injected under ram speed control, but it can be also injected under pressure control. In the present study, we have recorded the signals of pressure at three points during the filling of a spiral shape part. The behaviors of two rubber compounds have been studied using a variety of combinations of process conditions (including mold temperature, mass temperature, ram speed and injection molding with and without pressure holding stage). In all conditions, the transducer located in proximity to the gate exhibits pressure decay at the last stage of mold filling. Initial CAE simulations have been carried out using Moldflow software to check the capability of this sort of software to calculate pressure decay during the filling stage.

Time-dependent Springback

Draw-bend tests performed some years ago on four aluminum alloys (2008-T4, 5182-O, 6022-T4, and 6111-T4) revealed that specimens can continue to change shape for long periods, up to 15 months, following forming and unloading [1]. Contemporaneous tests of autobody steels (DQSK, AKDQ and HSLA steels) tested under identical conditions showed no such time-dependent springback over a 7 year period [2]. Current, preliminary results for a few advanced high strength steels (DP600, DP800, DP980 and TRIP780) revealed time-dependent springback at room temperature; the sign of the springback reversing for certain combinations of process conditions. Time-dependent behavior of four advanced high strength steel was measured and creep-simulated for various test conditions. Comparisons show qualitative agreement, but the simulations over-predict the magnitude of the effect

Dispersion strengthening of copper by internal oxidation of rapidly solidified Cu-RE alloys

Combination of rapid solidification and internal oxidation was used for producing a fine dispersion of rare earth oxide particles in the copper matrix. An overall microstructural analysis has shown that the internal oxidation temperature, the rapidly solidified microstructure and its changing ahead of the internal oxidation front strongly influence the mechanism of the internal oxidation process and the resulting microstructure. The internal oxidation in a Cu-Yb alloy took place mainly by direct oxidation of intermetallic particles. Contrary to this, in a Cu-Er alloy two mechanisms of internal oxidation have been clearly observed: (i) Dissolution of intermetallic particles ahead of the internal oxidation front and oxidation of the erbium from the solid solution and (ii) direct oxidation of the Cu-Er intermetallic particles. While a reasonable optimum combination of processing conditions at internal oxidation in the solid state, yielding suitable oxide dispersions, seems to have been identified for the Cu-Er alloy, the same was not true for the Cu-Yb alloy. However, the internal oxidation of the Cu-Yb alloy in the semisolid state, which occurs by alternation of two processes - Yb oxides precipitation and Cu matrix solidification - led to a relatively uniform dispersion of Yb oxide particles.