Investigation of surface roughness of aluminium solid mould investment castings

Solid investment moulds are used for precious or non-precious metals and alloys castings, the most common application areas are dental prosthesis and jewellery fabrications. Investment casting is known for high dimensional accuracy and smooth surface finish. Casting of ultra-thin sections and small complex parts require vacuum assisted or centrifugal filling. In this study, solid investment casting of aluminium has been tried and surface quality of the castings was investigated. Specially designed steppedwedge surface roughness specimens were produced with A413 aluminium alloy casting into gypsum bonded solid moulds. Casting operations were carried out in two ways; the first only with gravitational force and the second with vacuum assistance. Surface roughness of as cast specimens were measured, effects of section thickness, vacuum assistance and location of the pattern on the wax tree were determined.     

Rapid detection of fat adulteration in bakery products using Raman and near-infrared spectroscopies

Adulteration is frequently encountered in the food industry and can be identified using currently available techniques. Infrared and Raman spectroscopic procedures are the most attractive techniques regarding fats and oils. The objective of this study was to determine the adulteration of the fat source (margarine or butter) in bakery products using Raman and near-infrared (NIR) spectroscopies. Margarine and butter samples were purchased at local markets in Turkey and examined using Raman and NIR devices. A mixture (50 % margarine : 50 % butter) of fat samples was examined as well. The NIR and Raman spectral output data of all the fat samples were processed using principal component analysis (PCA). Good classification was obtained for margarine, butter and the 1:1 adulterated mixture. The chosen bakery product (cake) was produced using the same fat samples according to the method of the American Association of Cereal Chemists. Then, the fat fraction was extracted from the cakes with n-hexane. Extracted fat samples from the cakes were examined as before. PCA was applied to Raman and NIR spectral data to achieve the separation of fat sources in the cakes. PCA was also validated in each of the two stages. Significant decomposition was observed in the Raman study in contrast to the NIR study. A chemometric comparison was also applied to processed (baked) fat samples in cakes and purchased samples by PCA to assess the effects of heat treatment on sample spectra. Raman spectroscopy with multivariate analyses such as PCA can be used to detect the adulteration of the fat source in bakery products in a faster and more suitable way than the other methods.     

Influence of nanoparticle surface chemistry and size on supercritical carbon dioxide processed nanocomposite foam morphology

Creating polymer foams with controlled pore size and pore density is an important part of controlling foam properties. The addition of nanoparticles has been shown to cause heterogeneous nucleation and can be used to reduce pore size. In the current study, the effects of filler size and filler surface chemistry on pore nucleation in silica/PMMA nanocomposites are investigated. It was found that as the nanofiller size decreased, the pore density increased by a factor of 2-3 decades compared to that of unfilled PMMA (pore cell densities above 10¹² cells/cm³ were obtained). In addition, fluorination of the silica nanoparticle surface led to decreased pore size without changing the degree of silica aggregation and overall density. By monitoring the pore density as a function of pressure, a qualitative comparison was obtained that showed that fluorination of the nanoparticle reduced the critical free energy of nucleation.     

A new method for registration-based medical image interpolation

A new technique is presented for interpolating between grey-scale images in a medical data set. Registration between neighboring slices is achieved with a modified control grid interpolation algorithm that selectively accepts displacement field updates in a manner optimized for performance. A cubic interpolator is then applied to pixel intensities correlated by the displacement fields. Special considerations are made for efficiency, interpolation quality, and compression in the implementation of the algorithm. Experimental results show that the new method achieves good quality, while offering dramatic improvement in efficiency relative to the best competing method.     

Critical Submergence for Multiple Pipe Intakes

The critical submergence for a group of multiple pipe intakes is predicted using a “superposition method” based on a potential flow solution. Experiments on groups of two, three, and four intakes were conducted. Experimental and theoretical results indicate that intakes in a group mutually influence the discharge into an individual intake. Therefore, the critical submergence for an intake in a group becomes larger than that for an isolated intake under identical flow conditions. The agreement between the theoretical and experimental results is found to be satisfactory.