On-line 3-D system for the inspection of deformable parts

In spite of the development of automated tolerance inspection systems for manufactured parts over the years, there are still processes that inevitably require manual intervention making full automation impossible in most cases; in particular when dealing with deformable parts. In most current industrial inspection systems, a deformable part under inspection must first be mechanically constrained on a rigid support or jig so as to be able to compare it with its nominal shape. This paper presents a new system to perform real-time surface inspection of deformable parts that does not require fixturing. Instead, the proposed system applies virtual forces to the part??s CAD model as if the part was installed in the fixturing device. Normally, a precise finite element method (FEM) simulation should be used to approximate the deformation that appends when the part is installed in the device. Even with a fast parallel computer, FEM is far from being real-time and cannot be used for on-line inspection. In the proposed system, a radial basis function approximation of the FEM simulation is trained off-line and used to speed-up the simulation by an order of magnitude. Experimental evaluation of the proposed system is presented for three plastic parts. Using the proposed scheme, an approximation of 0.25?mm compared with the real deformation was obtained. In this paper, statistical results are presented such as the average deviation, standard deviation, and processing time between the approximations obtained with the proposed method and with the finite element method applied to the full CAD model.     

Effect of dietary n−3 and n−6 polyunsaturated fatty acids on lipid-metabolizing enzymes in obese rat liver

This study was designed to examine whether n−3 and n−6 polyunsaturated fatty acids at a very low dietary level (about 0.2%) would alter liver activities in respect to fatty acid oxidation. Obese Zucker rats were used because of their low level of fatty acid oxidation, which would make increases easier to detect. Zucker rats were fed diets containing different oil mixtures (5%, w/w) with the same ratio of n−6/n−3 fatty acids supplied either as fish oil or arachidonic acid concentrate. Decreased hepatic triacylglycerol levels were observed only with the diet containing fish oil. In mitochondrial outer membranes, which support carnitine palmitoyltransferase I activity, cholesterol content was similar for all diets, while the percentage of 22∶6n−3 and 20∶4n−6 in phospholipids was enhanced about by 6 and 3% with the diets containing fish oil and arachidonic acid, respectively. With the fish oil diet, the only difference found in activities related to fatty acid oxidation was the lower sensitivity of carnitine palmitoyltransferase I to malonyl-CoA inhibition. With the diet containing arachidonic acid, peroxisomal fatty acid oxidation and carnitine palmitoyltransferase I activity were markedly depressed. Compared with the control diet, the diets enriched in fish oil and in arachidonic acid gave rise to a higher specific activity of aryl-ester hydrolase in microsomal fractions. We suggest that slight changes in composition of n−3 or n−6 polyunsaturated fatty acids in mitochondrial outer membranes may alter carnitine palmitoyltransferase I activity.     

A new short-path distillation system applied to the reduction of cholesterol in butter and lard

A molecular distillation plant, built particularly to increase the separation efficiency and to obtain safer working conditions, was tested to remove cholesterol from anhydrous butter and lard. A preliminary experiment was carried out with butter to evaluate the fractionation obtained at temperatures between 190 and 250°C and residual pressures between 10⁻³ and 10⁻⁴ torr. A second experiment was carried out at 185°C and at the maximum operational vacuum, evaluating the fractionation achieved within a time scale between 30 and 180 min. Cholesterol was almost completely removed during the second hour with minimal loss of low-molecular weight triglycerides. An experiment was carried out with lard at 250°C and maximum achievable operational vacuum (10⁻⁴ Torr), lasting approximately 6 h, and cholesterol was removed almost completely during the second hour without significant modifications in the triglyceride composition. This situation remained constant throughout the duration of the test.     

N-alkyl-3-vinylpyridinium salts: homopolymerization of the hexadecyl derivative and behaviour study of the polymer in aqueous media

Summary We report on the preparation and the characterization of R-alkylated quaternary salts (with RCCH₃, C₁₂H₂₅, C₁₆H₃₃, X=Br^-) derived from 3-vinylpyridine (3-VP). Our first attempts on free radical polymerization of 1-hexadecyl-3-vinylpyridinium bromide in benzene solution were described. The viscosimetric behaviour and binding of dye (Methyl Orange) to this homopolymer in aqueous media were interpreted as the formation of compact coils resulting in the presence of hydrophobic microdomains.     

Mechanism of superacid catalyzed alkane activation: theoretical ab initio studies of pentacoordinated carbonium ion rearrangement

A theoretical ab initio study of the interconversion of pentacoordinated carbonium ions was carried out. For the isobutonium cations it was found that the respective C-carbonium ions were lower in energy than the H-isobutonium ions. Nevertheless, the interconversion of the 1-H-isobutonium cation in the C-isobutonium ion is a barrierless process. This suggests that product arisen from C–C protonation in liquid superacid and zeolite catalyzed alkane activation may be formed by protonation in the outer and more accessible primary C–H bonds of isobutane, rather than by direct protonation of the inner and more steric demanding C–C bonds. This revised version was published online in June 2006 with corrections to the Cover Date.     

Transfer, Perception, and Activity of Male Pheromone of Acrolepiopsis assectella with Special Reference to Conspecific Male Sexual Inhibition

In the leek moth, Acrolepiopsis assectella, the male, stimulated by a calling female, produces a sexual pheromone that is active on the female. The male-produced pheromone blend contains eight alkanes previously isolated from the male hair-pencils. We used EAG techniques to study the effect of the pheromone on females reared on leek or on artificial diet and on males reared on leek. The optimal stimulation duration appeared to be 1.6 sec exposure to the pheromone or components. The concentrations tested on the antenna were of the order of 10¹² molecules/cm³. The hair-pencil extract tested was of an estimated concentration of around 10⁹ molecules/cm³. The antennal responses are expressed relative to responses to a standard, amyl acetate, but also as an absolute value. Generally, females reared on artificial diet and males reared on leek responded better than females reared on leek. Of the alkanes tested, those present in hair-pencils gave higher responses, with hexadecane always giving the strongest response. A possible inhibiting activity of male leek moth pheromone on the sexual behavior of conspecific males was investigated. The behavior of sexually stimulated males was observed in the presence of other males, hair-pencil extracts, and different compounds either pure or in a mixture. The experiments established that in this species, male pheromone inhibits wing fluttering duration of conspecific males. This inhibition was obtained not only with fluttering males as a source of pheromone but also with all the alkanes tested. The inhibition was due to hair-pencil chemicals, particularly if these were perceived by olfaction plus contact. Wing fluttering increased the inhibitory activity of male-derived alkanes.     

Flow patterns and sediment deposition in rectangular shallow reservoirs

This work involves the experimental investigation of flow patterns, preferential regions of deposition and trapping efficiency in rectangular shallow reservoirs. The main flow patterns that can be encountered in rectangular shallow reservoirs are described: symmetrical flows without any reattachment point (S0), asymmetrical flows with one reattachment point (A1) and asymmetrical flows with two reattachment points (A2). The influence of geometrical and hydraulic parameters on reattachment lengths is intensively investigated. A shape parameter is introduced to classify symmetrical and asymmetrical flows. For each flow pattern, the preferential regions of deposition are studied. To conclude, a number of practical recommendations are given. Reservoirs with a shape parameter lower than 6.2 limit sediment deposition. Reservoirs with a shape parameter greater than 6.8 are favourable for sediment deposition. Finally, perspectives for maximizing and minimizing deposition are given, respectively by exploiting the great trapping potential of the flow pattern A1 and the poor trapping potential of the flow pattern S0.     

Study on transient heat transfer through multilayer thermal insulation: Numerical analysis and experimental investigation

This paper reports on a numerical and experimental study of heat transfer phenomena through two different multilayer fibrous insulations for building applications. The investigated samples were composed of different layers of fibrous materials and aluminium foils, placed between one or two air gaps in the vertical dimension. An experimental apparatus (a guarded hot box) has been used to measure heat transfer through the samples, while a finite volume numerical model combined radiation/conduction heat transfer was developed to predict the temperature distribution and heat transfer in such insulation systems comprised of the materials separated by multiple reflective foils. The model takes into account the coupling between the solid conduction of the fibrous system and the gaseous conduction and radiation. The radiation heat transfer through the insulation system has been modelled via the two flux approximation. The numerical results were compared with the experimental data from the guarded hot box for model validation, as well as to assess the effectiveness of the reflective foils in changing the resistance of the insulations. The comparative verification of the model showed that the numerical results were consistent with the experimental data through the environmental conditions under examination.     

Trace organic solutes in closed-loop forward osmosis applications: Influence of membrane fouling and modeling of solute build-up

In this study, trace organics transport in closed-loop forward osmosis (FO) systems was assessed. The FO systems considered, consisted of an FO unit and a nanofiltration (NF) or reverse osmosis (RO) unit, with the draw solution circulating between both units. The rejection of trace organics by FO, NF and RO was tested. It was found that the rejection rates of FO were generally comparable with NF and lower than RO rejection rates. To assess the influence of fouling in FO on trace organics rejection, FO membranes were fouled with sodium alginate, bovine serum albumin or by biofilm growth, after which trace organics rejection was tested. A negative influence of fouling on FO rejection was found which was limited in most cases, while it was significant for some compounds such as paracetamol and naproxen, indicating specific compound-foulant interactions. The transport mechanism of trace organics in FO was tested, in order to differentiate between diffusive and convective transport. The concentration of trace organics in the final product water and the build-up of trace organics in the draw solution were modeled assuming the draw solution was reconcentrated by NF/RO and taking into account different transport mechanisms for the FO membrane and different rejection rates by NF/RO. Modeling results showed that if the FO rejection rate is lower than the RO rejection rate (as is the case for most compounds tested), the added value of the FO-RO cycle compared to RO only at steady-state was small for diffusively and negative for convectively transported trace organics. Modeling also showed that trace organics accumulate in the draw solution.     

Geodesign application for bio-swale design: rule-based approach stormwater management for Ottawa Street North in Hamilton,Ontario

With increases in storm frequency and intensity, municipalities are finding new ways of managing stormwater. Solutions require collaboration across planning disciplines and input from an informed public. This study compares a system of bioswales to existing curb and gutter infrastructure in a post-industrial streetscape of Hamilton, Ontario. Using the geodesign process, a section of Ottawa St. North was modelled to show how green infrastructure can ease the burden on aging, combined sewer systems. Qualitative data was gathered from residents of the neighbourhood through field notes, and quantitative geospatial data through GIS. Parametric modelling was used to generate a design, and scenarios created to show resulting impacts on stormwater run-off. The model was posted online as an interactive presentation, accessible to all stakeholders for review and comment. The results of the study demonstrate powerful new tools that can assist landscape architects in designing, collaborating and communicating stormwater strategies.