A cathode support structure for use in a magnetron oscillator experiment

A low temperature co-fired ceramic (LTCC) material system has been used to develop a protype field emission cathode structure for use in an experimental magnetron oscillator. The structure is designed for used with 30 gated field emission array (GFEA) die electrically connected through silver metal traces and electrical vias. To approximate a cylinder, the cathode structure (48 mm long and 13.7 mm in diameter) is comprised of 10 faceted plates which cover the GFEA dies. Slits in the facet plates allow electron injection. The GFEA die (3 mm × 8 mm) are placed in axial columns of 3 and spaced azimuthally around a cylindrical support structure in a staggered configuration resulting in 10 azimuthal locations. LTCC manufacturing techniques were developed in order to fabricate the newly designed cathode with seven layers wrapped to form the cylinder with electrical traces and vias. Two different cathode wrapping techniques and two different via filling techniques were studied and compared. Two different facet plate manufacturing techniques were studied. Finally, four different support stand configurations for firing the cylindrical structure were also compared with a square post stand having the best circularity and linearity measurements of the fired structure.     

The effects of dietary α-tocopheryl acetate supplementation and modified atmosphere packaging (MAP) on the quality of lamb patties

Contributions to water retention capacity (% WRC) and texture changes were determined for pork by-products (lung lobes, kidneys), chicken viscera (head, feet and viscera) and mechanically separated chicken (MSC) as affected by pH and various salts in a high-moisture model system. The % WRC for meat by-products and MSC was increased by increased pH (4.5-6.8). Pork lungs and MSC had the highest % WRC (p<0.05) among the meat by-products. Meat by-product % WRC was not signifcantly (p>0.05) affected by salt (2%), phosphate (0.3%) or NaOH (0.075%). Chicken viscera had the lowest (p<0.05) mean texture measurements among the meat by-products and MSC. Strong negative correlations (p<0.05) were obtained for texture with total collagen, soluble collagen and high ionic strength soluble (HIS) proteins. These results should be considered for product quality changes when these by-products are used in formulation of high moisture pet food products.     

A model to predict long-term performance of vapor-phase bioreactors: a cellular automaton approach

A novel numerical model was constructed to predict performance of vapor-phase bioreactors (VPBs) operated over extended periods. This model incorporates two unique features to simulate changes in pollutant removal efficiency and biomass accumulation: (1) total biomass is divided into two microbial components, active and inactive biomass, and (2) biomass growth and biofilm thickness changes are simulated by means of a cellular automaton (CA) approach. The CA approach, a differential-discrete algorithm, numerically allows the excess quantity of biomass in each numerical element to move toward the biofilm surface as biomass accumulates. One set of experimental bioreactor data was used to estimate unknown model parameters. A 90-day simulation using the estimated parameters agreed with pollutant removal and biomass accumulation profiles determined experimentally. Four additional model simulations using the same estimated model parameters were generally consistent with experimental data collected from a series of toluene-degrading VPBs operated over a range of conditions. Model predictions imply that the decline in bioreactor performance observed over extended operation was caused by a decline in the active biomass fraction and a decrease in the biofilm specific surface area. This CA model provides insight into biomass accumulation during complex bioreactor operation and improves our capability to predict long-term VPB performance.     

The use of near infrared reflectance spectroscopy to identify the origin of oak shavings used in wine aging

Near infrared (NIR) reflectance spectroscopy combined with chemometrics was used to classify toasted and untoasted oak wood shavings sourced from two countries (France and USA). Oak wood shaving samples (n = 96) were scanned in the NIR region (680–2,500 nm) using a monochromator instrument operating in reflectance mode. Principal component analysis, partial least squares discriminant analysis (PLS-DA) and linear discriminant analysis (LDA) were used to classify the samples according to their country of origin and level of toasting. Full cross validation (leave-one-out) was used as the validation method when classification models were developed. Correct classification rates of 83, 87 and 100 % for samples sourced from USA, France and toasted treatment were obtained using PLS-DA. For LDA, correct classification rates of 80.4, 85 and 100 % were achieved for samples sourced from USA, France and toasted treatment, respectively. These results demonstrated the ability of NIR spectroscopy to discriminate between oak wood shavings sourced from two different countries and two levels of toasting.     

Fouling of microfiltration and ultrafiltration membranes by natural waters

Membrane filtration (microfiltration and ultrafiltration) has become an accepted process for drinking water treatment, but membrane fouling remains a significant problem. The objective of this study was to systematically investigate the mechanisms and components in natural waters that contribute to fouling. Natural waters from five sources were filtered in a benchtop filtration system. A sequential filtration process was used in most experiments. The first filtration steps removed specific components from the water, and the latter filtration steps investigated membrane fouling by the remaining components. Particulate matter (larger than 0.45 microm) was relatively unimportant in fouling as compared to dissolved matter. Very small colloids, ranging from about 3-20 nm in diameter, appeared to be important membrane foulants based on this experimental protocol. The colloidal foulants included both inorganic and organic matter, but the greatest fraction of material was organic. When the colloidal fraction of material was removed, the remaining dissolved organic matter (DOM), which was smaller than about 3 nm and included about 85-90% of the total DOM, caused very little fouling. Thus, although other studies have identified DOM as a major foulant during filtration of natural waters, this work shows that a small fraction of DOM may be responsible for fouling. Adsorption was demonstrated to be an important mechanism for fouling by colloids.     

Effect of heat-moisture treatment on the formation and physicochemical properties of resistant starch from mung bean (Phaseolus radiatus) starch

Mung bean starch was subjected to a range of heat-moisture treatments (HMT) based on different moisture contents (15%, 20%, 25%, 30%, and 35%) all heated at 120 °C for 12 h. The impact on the yields of resistant starch (RS), and the microstructure, physicochemical and functional properties of RS was investigated. Compared to raw starch, the RS content of HMT starch increased significantly, with the starch treated at 20% moisture having the highest RS content. After HMT, birefringence remained at the periphery of the granules and was absent at the center of some granules. The shape and integrity of HMT starch granules did not change but concavity was observed under scanning electronic microscopy. Apparent amylose contents of HMT starch increased and the HMT starch was dominated by high molecular weight fraction. Both the native and HMT starches showed A-type X-ray diffraction pattern. Relative crystallinity increased after HMT. The gelatinization temperatures (To, Tp, and Tc), gelatinization temperature range (Tc–To) and enthalpies of gelatinization (ΔH) increased significantly in HMT starch compared to native starch. The solubility increased but swelling power decreased in HMT starches. This study clearly shows that the HMT exhibited thermal stability and resistance to enzymatic hydrolysis owing to stronger interactions of starch chains in granule.     

A small-scale comparison of the equivalence of paper-and-pencil and computerized versions of student end-of-course evaluations

This study compared responses to two versions of an end-of-course evaluation instrument completed by graduate students: the traditional printed form completed using pencil and paper, and a microcomputer-based form that presented equivalent items and accepted student responses. A finding of no significant difference in favorableness of composite ratings between the two versions prompted the researcher to perform item-by-item analyses of the two instruments. These analyses revealed that ratings of the individual items on one instrument were highly correlated with the ratings of their matched corresponding items on the other instrument. The paper-and-pencil and computerized evaluation instruments were found to be of almost identically high reliability. Possible limitations of the findings and areas for future research are discussed.     

Automated process planning for parametric parts

The available automated CAPP solutions are mostly academic research or specific applications, which cannot be used in different environments. This paper presents a solution for automated process planning for parametric parts included in one CAPP environment with many other software components. It meets the planning requirements of any parts and products in a real industrial environment. This paper provides a brief overview of CAPP and a definition of the parametric parts used. The requirements of the CAPP environment are discussed and its concept and design characteristics are presented. A practical application of the CAPP environment is described in order to validate the proposed solution.