Computer Engineering

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    Temperature changes with die profiles in axisymmetric forward extrusion process
    (Journal of Applied Scence, Engineering and Technology, 2008) Ajiboye, J.S.; Adeyemi, M.B.
    Transient heat transfer and temperature change due to varying die opening shapes in a direct extrusion of lead have been numerically investigated and presented. Upper bound method of analysis was used to evaluate the internal heat generation due to plastic deformation and frictional heat at various stages of the extrusion process. At the extrusion die land region, temperature rises with increasing complexity of die openings geometry with I-shaped section, giving the highest temperature rise, followed by T-shaped section, rectangular, circular shaped die openings with square section die opening, giving the least temperature rise for any given extrusion parameter. The die land zone shows increasing temperature rise with increasing friction coefficient, while increasing friction coefficient has no overall effect on the dead metal zone temperature rise. Increasing die land length leads to increasing contact area between the extrudate and the die resulting in increasing frictional power. It is, therefore, seen that die land is one of the critical factors to consider avoiding surface cracking or hot-shortness in extrusion.
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    HISTOGRAM NORMALIZATION TECHNIQUE FOR PREPROCESSING MAMMOGRAPHIC IMAGES
    (LAUTECH Journal of Engineering and Technology, 2016) Adepoju, Temilola M.; Adeyemo, Temitope T.; Fagbola, Temitayo M.; Omidiora, Elijah O.; Olabiyisi, Stephen O.
    images requires high computational capabilities. Pre-processing is one of the most important step in the mammogram analysis due to poor captured mammographic image qualities. Pre-processing is basically used to correct and adjust the mammogram image for further study and classification. Many image pre-processing techniques have been developed over the past decades to help radiologists in diagnosing breast cancer. Most studies conducted have proven that a pre-processed image is easier for radiologist to accurately detect breast cancer especially for dense breast. Different types of techniques are available for preprocessing of mammograms, which are used to improve image quality, remove noise, adjust contrast, enhance the image and preserve the edges within the image. This paper acquired 20 digital mammograms from Mammographic Image Analysis Society (MIAS) database and uses Histogram Normalization algorithm for pre-processing of the mammograms. A percentage of 95% was obtained. It was observed that the pre-processed mammographic images displayed breast abnormalities clearer with little or no noise.
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    Tribological efficacy and stability of phospholipid-based membrane lubricants in varying pH chemical conditions
    (Biointerphases, 2016-01-04) Pawlaka, Zenon; Urbaniak, Wieslaw; Afara, Isaac O.; Yusuf, Kehinde Q.; Banaszak-Piechowska, Agnieszka; Oloyede, Adekunle
    In this study, the authors examine the influence of joint chemical environment by measuring changes in the tribological properties (friction coefficient and charge density) of contacting surfaces of normal and degenerated cartilage samples in bath solutions of varying pH (2.0–9.0). Bovine articular cartilage samples (n¼54) were subjected to several surface measurements, including interfacial energy, contact angle, and friction coefficient, at varying pH. The samples were delipidized and then subjected to the same measurement protocols. Our results reveal that the interfacial energy and charge density, which have been shown to be related to friction coefficient, decrease with pH in the acidic range and approach constant values at physiological (or synovial fluid) pH of 7.4 and beyond it, i.e., toward basic pH domain. The authors conclude that this rather complex response explains the long-term efficacy with respect to ageing and associated pH changes, of the phospholipid layers that facilitate the almost frictionless, hydration–lubrication involving contact in the mammalian musculoskeletal system.