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Elimination of solidification shrinkage defects in the casting of aluminum alloy
Rashid Ali,Muhammad Zafar,Tareq Manzoor,Woo-Young Kim,Muhammad Usman Rashid,Syed Zameer Abbas,Behzad Ahmed Zai,Muddassir Ali 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5
In this study, the analysis is carried out to optimize in-gate position and size of riser for casting mold. The baseline size of riser for the casting of boat propeller is based on geometric modulus and thermal analysis. The riser size is analyzed with thermal-volumetric numerical calculations to predict critical fraction solid (CFS) time and temperature gradient in casting. Simulation predictions are compared with inspection results of actual castings and found good qualitative agreement. The riser reached CFS temperature well before the castings’ cross-sectional transition regions. In feeding the molten metal, the in-gate is placed where the section modulus of casting is higher. However, the tongue of sand at in-gate increases the local cooling rate, resulting in early solidification and blockage of feeding path. The increase in riser size and in-gate position results in elimination of shrinkage cavities. An optical microscopy of the casting critical region is carried out to investigate the effect of numerical measures on internal closed microporosity and microstructure morphology.
Rashid Nawaz,Naghmana Rashid,Zulfiqar Ali,Asad U. Khan,M. Shahid Nazir,Noaman Ul-Haq 한국섬유공학회 2018 Fibers and polymers Vol.19 No.6
In this work we investigated the ablative response and thermal properties of phenolic resin (PR) blended acrylonitrile butadiene rubber (NBR) composites. PR was added to NBR in the proportion of 0, 5, 10, 20, 30, 40 and 50 phr by means of two-roll laboratory mill. PR remarkably improved ablation resistance and thermal properties of NBR/PR composite. The linear and mass ablation rates reduced to 21.3 % and 26.1 % respectively. The char content deposition increased from 0.19 to 26.8 %. Char layer produced by PR, obviously reduced the erosion rate of the NBR/PR composite relative to neat NBR (without PR). Detailed morphological studies of the composite and post-test (ablation) microstructure of char revealed that higher loading of PR in the rubber composite produced dense char layer firmly intact to the substrate. Furthermore, thermal stability of the composite improved by 22-23 ºC, however, thermal conductivity of the composite slightly increased by 0.115 W/mK for 50 Phr of PR loading as compared to the neat.
Rashid Ali Sindhu,M.K.Park,Saemahn Bhak,Behzad Ahmed Zai,Hassan Mehboob,Joongwon Lee 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Residual stresses deteriorate strength of materials adversely affecting quality of industrial products. A removable or a reduction of the residual stresses is an essential procedure in successful product developments. Effective and convenient methods are necessary for detection and evaluation of the residual stresses. In this investigation Hole Drilling Method is chosen for identification and a quantitative determination of the residual stresses of specimen in two groups under different laser welding speed conditions, 4.1 m/min and 5.1 m/min. Laser lap welding of SPCC sheet joints was investigated along the welding line at two locations, at the welding middle and end locations in the heat affected zone (HAZ). Based on the experimental results and the analysis, higher welding speed condition is predicted to reduce the residual stresses.
Rashid Ali Laghari,Ning He,Muhammad Jamil,Muhammad Irfan Hussain,Munish Kumar Gupta,Grzegorz M. Krolczyk 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.6
Metal matrix composites (MMCs) are lightweight, hard materials applied in heavy-duty applications such as automobile, aerospace, and electronics, as well as sports equipment. MMCs reveal exceptional physical and mechanical properties, including high strength, corrosion, wear resistance, higher stiffness, and toughness. However, owing to poor surface finish, accelerated tool wear, and high material removal cost, MMCs are categorized as difficult-to-cut composites. This article reviews sustainable machining under different lubrication and cooling approaches and the economics of the operation for MMCs. The study focuses on optimizing machinability factors, such as surface integrity, chip formation, tool wear, and sustainability analysis. To attain this goal, the review evaluates suitable cutting parameters for Aluminum, Titanium, Magnesium, and Copper-based metal matrix composites, which hitherto have not been explored or summarized comprehensively. This study provides strong guidance regarding selection of precise cutting parameters for MMCs. The findings of this review suggest that different cooling/lubrication technologies can optimize and improve the sustainability and machinability characteristics, extend tool life and surface quality, during the cutting operation.
CONCEPT AND MANAGEMENT OF ISTISQĀ' (OEDEMA) IN UNANI SYSTEM OF MEDICINE
Khan, Khalid Ali,Zakir, Mohammad,Khan, Shahid Ali,Khan, Rashid Ali Cellmed Orthocellular Medicine and Pharmaceutical 2021 셀메드 (CellMed) Vol.11 No.1
Ascites is the accumulation of fluid in the peritoneal cavity, and it is generally allied with liver disease like cirrhosis of the liver. The ascites is commonly associated with liver cirrhosis, malignancy, or cardiovascular disease today. The liver cirrhosis is the most significant cause of ascites in developed countries as per the available data. In the modern medicine system, the treatment includes the restriction of sodium intake, use of diuretics, and paracentesis done in severe cases. There are many side effects of synthetic chemical diuretics, and their long-term use is not recommended. The alternative medicine like Unani system of medicine provides natural diuretics and drugs which also have protective effects on kidney, liver and other internal organs. It is well known in all drug systems that the prognosis is poor in ascites, but the use of Unani herbal medicines can minimize the side effects caused by synthetic chemical diuretics. The natural herbs used for the management of ascites have fewer side effects as compared to synthetic drugs. The natural drugs can be used for longer duration and provide some dietary supplement which improves the quality of life. This review addressed the thorough treatment of ascites by natural diet and medications.
MANAGEMENT OF HASĀH WA RAML AL-KULYA (NEPHROLITHIASIS) IN UNANI SYSTEM OF MEDICINE: A REVIEW
Khan, Khalid Ali,Khan, Rashid Ali,Zakir, Mohammad Cellmed Orthocellular Medicine and Pharmaceutical 2020 셀메드 (CellMed) Vol.10 No.3
The kidneys are exposed to toxicants and waste product and can be affected easily by these toxicants and by products of the metabolism. The consumption of adequate water is necessary to remove waste and to keep kidney healthy. Deficiency of liquid in the blood leads to various adverse effects on the kidney. The most common adverse deficiency of liquid in blood is deposition of solid matter in the kidney and subsequently formation of kidney stone. Nephrolithiasis (kidney stone) can be treated by drugs if it is small in size but if it blocks the route due to its big size then surgery is the only way to remove it. The recurrence rate of the problem is very high and it may reappear within 10 years. In Unani literature Hasāh wa Raml al-Kulya (nephrolithiasis) is described in detail. As per Unani literature stagnation of Ghalīz mādda (filthy and viscous matter) in the kidney is the main cause of the formation of kidney stone. Various single and compound formulations drugs are described for the management of kidney stone which are very effective as well as safe. Management is divided into two parts i.e. symptomatic treatment to relieve pain and to methods adopted to remove stone from the kidney. Musakkin-i-Waja'(analgesic) drugs are used for pain while Mufattit-i-Hasāh (lithotriptic) and Mudirr-i-Bawl (Diuretic) drugs are used to remove stone. Majoon Aqrab, Qurs Kaknaj and Dawa-e-Gurda etc. are compound drugs mentioned in literature for removal of kidney stone. Single drugs like Alu Balu, Tukhm Khayar, and Kharkhask etc. are also used for same purpose.