A knowledge based feed-back control system for precision ELID grinding

Newer materials with excellent properties are of recent interest in the optical, electrical and electronics industries. Finishing of new materials for the required stringent specification stated by those industrial applications emerges the innovation of new techniques and processes in the field of manufacturing. Electrolytic in-process dressing (ELID) is one of those new manufacturing techniques which may produce mirror surface finish on various optical and non-optical materials. The easy implementation and the efficiency of the ELID technique have been drawing the attention of the optical manufacturing industries in the recent years. However, further improvements are essential in order to minimize the difficulties experienced during implementation and to extend its suitability for future applications. The authors propose a knowledge based feed-back control system for ELID grinding to eliminate the application difficulties and to improve the effectiveness of the process. This study aims to experiment and to analyze the various features of the developed feed-back control system. The main objective is to examine the effectiveness of the system for precision finishing of optical and non-optical harder materials. The possibilities to reduce the geometrical inaccuracies of the workpiece have been examined in this study. The results show that application of the feed-back control system minimizes the number of correction cycles necessary for precision finishing of hard materials, such as, quartz.     

Origins of colour in Yb–Si–Al–O–N glasses

Previous work has shown that some RE-Si–Al–O–N glasses are coloured. In particular, oxynitride glasses containing Ytterbium were observed to display a wide range of colours depending on their composition. The reasons for this were not immediately evident. As Ytterbium and Europium have been reported to display valency variations in silicate glasses and α-sialons, the current study prepared a range of Yb–Si–Al–O–N glasses, characterised them by means of X-ray photoelectron, Raman, FTIR and UV–vis spectroscopy as well as thermal analysis and X-ray diffraction. The correlation between the structural features of the glasses with the changes in colour occurring when varying the Yb:Al ratio were investigated. Ytterbium garnet was found to be the source of colour change in the Yb–Si–Al–O–N in the compositions studied.     

Correlation of Back Optic Zone Radius measurement of rigid contact lenses with radiuscope and keratometer

PurposeTo investigate the accuracy of Back Optic Zone Radius (BOZR, base curve) measurements with manual keratometer for spherical polymethylmethacrylate (PMMA) lenses.Methods100 spherical PMMA contact lenses were selected randomly from the trial sets. One investigator measured the BOZR with radiuscope. The second investigator measured the BOZR with keratometer. The two investigators were masked to each other's readings. As the keratometer is designed to measure a convex corneal surface, the BOZR readings are less than actual radii. A correction factor of 0.025 was used to have corrected keratometers readings.ResultsThere was a high correlation between the BOZR measurement with radiuscope and the uncorrected (Pearson's correlation coefficient, r = 0.99) and corrected (r = 0.99) measurements with keratometer. The mean difference between BOZR measurement with radiuscope and the uncorrected and corrected measurements with keratometer were 0.003 mm (p = 0.62) and ?0.024 mm (p < 0.001) respectively. The 95% limits of agreement for the BOZR measurements with radiuscope and the uncorrected and corrected measurements with keratometer were ?0.11 to 0.11 mm and ?0.14 to 0.09 mm respectively.ConclusionWe found that the uncorrected BOZR measurements with keratometer were similar to the BOZR measurements with radiuscope. With unavailability of radiuscope in majority of contact lens practice, keratometer can be used to measure the BOZR of contact lenses.     

Utilization of organically stabilized proteinous solid waste for the treatment of coloured waste‐water

BACKGROUND: Solid waste emanating from tanneries contains a high percentage of protein with raw trimmings from hides constituting a significant percentage of the solid waste. In this study, organically stabilized trimmings (OST) have been used as an adsorbent material for removal of colour from waste‐water. RESULTS: Various parameters such as adsorbent dosage, dye concentration and pH have been optimized. The effect of neutral salts on the dye adsorption capacity of OST has also been studied. The adsorption of dye by OST follows the Freundlich isotherm. More than 99% removal of colour has been achieved. Commercial trials prove the potential use of organically stabilized trimmings for the treatment of colored wastewater. CONCLUSIONS: Dye loaded OSTs have been employed in the manufacture of a tanning salt, which can be used in the leather industry. Thus, a holistic solution to the challenging solid waste disposal problem has been developed. Copyright © 2009 Society of Chemical Industry     

Supporting Content-Based Retrieval in Large Image Database Systems

In this paper, we investigate approaches to supporting effective and efficient retrieval of image data based on content. We firstintroduce an effective block-oriented image decomposition structure which can be used to represent image content inimage database systems. We then discuss theapplication of this image data model to content-based image retrieval.Using wavelet transforms to extract image features,significant content features can be extracted from image datathrough decorrelating the data in their pixel format into frequency domain. Feature vectors ofimages can then be constructed. Content-based image retrievalis performed by comparing the feature vectors of the query imageand the decomposed segments in database images.Our experimental analysis illustrates that the proposed block-oriented image representationoffers a novel decomposition structure to be used tofacilitate effective and efficient image retrieval.     

Determining the freshness of fruits in the food industry by image classification using transfer learning

Multimedia Tools and Applications - Convolutional neural networks (CNNs) play a significant role in a number of computer vision applications like image classification and object detection. Past...     

Role of green tea polyphenol crosslinking in alleviating ultraviolet‐radiation effects on collagen

The widespread application of collagen warrants studies on the effects of ultraviolet (UV) radiation on stabilized collagen. The negative impact of UV radiation is well known. Because collagen is used as a biomaterial in various biomedical applications, knowing the effects of UV irradiation on stabilized collagen has become essential. In this study, the effects of UV irradiation on collagen stabilized with green tea polyphenols, that is, Acacia mearnsii (wattle), and catechin has been studied. The fluorescence intensity has been found to decrease with irradiation for native and wattle‐treated collagen. Spectral studies have indicated that the photodegradation products increase after irradiation for native collagen, whereas collagen treated with catechin or A.mearnsii exhibits different responses depending on the duration of the irradiation. The duration of the irradiation has a significant influence on polyphenol‐treated collagen. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

A fundamental study on the mechanism of electrolytic in-process dressing (ELID) grinding

Demands for high quality surface finish, dimensional and form accuracy are required for optical surfaces and it is very difficult to achieve these using conventional grinding methods. Electrolytic in-process dressing (ELID) grinding is one new and efficient method that uses a metal-bonded diamond grinding wheel in order to achieve a mirror surface finish especially on hard and brittle materials. However, studies reported so for have not explained the fundamental mechanism of ELID grinding and so it has been studied here by conducting experiments to establish optimal grinding parameters to obtain better surface finish under various in-process dressing conditions. In this research the results show that the cutting forces are unstable throughout the grinding process due to the breakage of an insulating layer formed on the surface of the grinding wheel; however, a smoother surface can be obtained using a high dressing current duty ratio at the cost of high tool wear. ELID grinding is efficient for feed rates of less than 400 mm/min, and surface cracks are observed when it exceeds this limit.     

Pt based nanocomposites (mono/bi/tri-metallic) decorated using different carbon supports for methanol electro-oxidation in acidic and basic media

Pt based mono/bi/tri-metallic nanocomposites on different carbon based supports (activated carbon (AC), carbon nanotubes (CNTs) and carbon nanofibers (CNFs)) were synthesised and Pt surface enrichment achieved. The overall theoretical metallic content (Pt + Au + Sn) was 20% (w/w) in all mono/bi/tri-metallic nanocomposites and was found to be uniformly distributed in the supporting matrix (80%). The surface morphology and composition of the synthesised materials was characterised using scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), while cyclic voltammetry was employed in order to confirm their typical metallic electrochemical characteristics. Electrochemical measurements indicated that Pt(2)Au(1)Sn(1) trimetallic catalysts demonstrated a significantly higher electrochemically active surface area relative to activated carbon supported PtAu based bimetallic counterparts. The results show that the CNT based trimetallic catalyst (Pt(2)Au(1)Sn(1)/CNT) showed greatest electroactive surface area (49.3 m(2)/g) and current density for methanol oxidation in acidic (490 mA mg(-1) Pt) as well as basic (1700 mA mg(-1) Pt) conditions. Results demonstrated that in comparison to Au/C and Sn/C (no/negligible response), the presence of a small amount of Pt in the Au and Sn based nanocomposites, significantly modified the catalytic properties. The activated carbon supported bimetallic (Pt(1)Au(3)/C) catalyst showed reasonably good response (260 mA mg(-1) Pt) among all bimetallic nanomaterials examined. The current response achieved for Pt(2)Au(1)Sn(1)/CNT was 1.9 times (in acidic media) and 2.1 times (in basic media) that for synthesised Pt/C in terms of per mg Pt activity. Overall the methanol oxidation studies demonstrated that the presence of Au and Sn in Pt based catalysts strongly indicated their capacity to reduce the precious Pt content required for this application, demonstrating the role of Au in improving current/potential response and signifying the importance of supporting matrices.