1,332 research outputs found

    NUMERICAL PREDICTION OF SOLITARY WAVE FORMATION OF A PLANING HULL IN SHALLOW WATER CHANNELS

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    This paper uses a CFD (Computational Fluid Dynamics) analysis to investigate the shallow water effects on prismatic planing hull. The turbulence flow around the hull was described by Reynolds Navier Stokes equations RANSE using the k-ɛ turbulence model. The free surface was modelled by the volume of fluid (VOF) method. The analysis was steady for all the range of speeds except those close to the critical speed range due to the propagation of the planing hull solitary waves at this range. In this study, the planing hull lift force, total resistance, and wave pattern for the range of subcritical speeds, critical speeds, and supercritical speeds have been calculated using CFD. The numerical results have been compared with experimental results. The pressure distribution on the planing hull and its wave pattern at critical speed in shallow water were compared with those in deep water

    Numerical and experimental investigations on efficient design and performance of hydrokinetic Banki cross flow turbine for rural areas

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    Micro hydrokinetic energy scheme presents an attractive, environmentally-friendly and efficient electric generation in rural, remote and hilly areas. However, this scheme is yet to be fully discovered, as researchers are still searching for solutions for the main problems of low velocity of current in the open flow channels and low efficiency of hydrokinetic turbines. This research proposes a novel system configuration to capture as much kinetic energy as possible from stream water current. This system, known as bidirectional diffuser augmented (BDA) channel, functions by utilizing dual directed nozzles in the flow and is surrounded by dual cross flow/Banki turbines. It is also important to obtain the efficient design parameters of the turbines to use in the current configuration. The appropriate angle is important in order to guide the flow to touch the blades more perpendicularly to capture as much torque and power as possible. Hence, experimental and numerical investigations have been carried out in this research paper to study the performance characteristics of the CFT configuration applied in BDA system and investigate the effects of blades’ inlet and outlet angles of CFT runners on the internal flow characteristics and efficiency. In this study, four different runners with various inlet and outlet angles of two CFT have been investigated. The CFD results have been validated with the experimental work and proven acceptable with flow pattern and performance characteristics. The results of the current study conclude that the maximum power coefficients (Cp) of 0.612 and 0.473 for lower and upper turbines are recorded for best runner angles of Case 3

    Resistance prediction of innovative semi SWATH design concept in shallow water

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    Many analysis have been conducted to evaluate performance of High Speed Craft (HSC). One of the important analysis is resistance analysis of multihull in shallow water. Ship operating in shallow water experiences increasing of resistance due to change in potential flow and wave pattern. In this paper, shallow water performance has been studied for one type of HSC design concept, Semi SWATH hull form. The hulls are installed with fin stabilizers to reduce dynamic motion effect. Resistance component of the hull, trim and maximum wave amplitude around the hull are obtained from the calm water test in shallow water. These criteria are important in analysing pattern of Semi-SWATH resistance in shallow water flow around hull. The fore fin angle is fixed to zero degree while the aft fin angle is varied for 0, 5, 10 and 15 degree. For each configuration, the investigation is conducted with range of Depth Froude Number from 0.65 to 1.2. From the analysis, it is found that resistance, wave pattern and trim of Semi SWATH is affected by fin angle

    A rare case of giant dermoid cyst with ipsilateral paratubal cystadenoma during pregnancy

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    Dermoid cysts are considered the most common ovarian cysts in adolescents and pregnant women. In rare cases, they can attain a huge size. Paratubal cysts are also common in adolescents. They are usually simple cysts present in the broad ligament. In this case, we report a giant dermoid cyst with ipsilateral paratubal serous cystadenoma discovered during pregnancy of a 20-year-old primigravida. Both cysts were managed conservatively, and then removed successfully at the time of cesarean section by cystectomy

    Comparison of serum cystatin C and creatinine based methods in detection of early renal dysfunction in critically ill patients

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    Early detection of renal dysfunction is of importance inthe care of critically ill patients. Cystatin C was proposedto be superior to serum creatinine in estimation of renal function. This work aimed to compare serum cystatin Cto serum creatinine and creatinine based formulae indetection of early decline in renal function at a singlepoint in critically ill patients. Fifty critically ill patientsadmitted to Cairo University Hospitals ICUs - Egypt wereincluded. Patients with chronic renal disease,thyroid disease, malignancy, patients receivingcorticosteroid therapy, with serum creatinine > 1.4 mg/dland patients receiving diuretics or large volumes of IVfluids were excluded. Serum creatinine, serum cystatinC, adjusted creatinine clearance (Adj Ccr), estimatedGFR (eGFR) by modification of diet in renal disease(MDRD), abbreviated MDRD (abb MDRD) andCockcroft-Gault (CG) formulae were measured. Patientswith renal dysfunction (adj Ccr < 80 ml/min/1.73m2)were 26 (52%) in number. Patients with renaldysfunction and high serum creatinine were 12/26(46.2%) while those with high cystatin C were 23/26(88.5%). Cystatin C was found to be significantlycorrelated with serum creatinine, adj Ccr and eGFR by all studied formulae. Using receiver operatingcharacteristic (ROC) analysis; AUC for Cystatin C(0.976) was more than that for eGFR by abb MDRD(AUC=0.839), MDRD (AUC=0.822), CG formulae(AUC=0.808) and serum creatinine (AUC=0.710)respectively. In conclusion; cystatin C was found to bebetter than serum creatinine, eGFR by abb MDRD,MDRD and CG formulae in detection of early renaldysfunction at a single point in critically ill patients

    Effects of different mycotoxins on humans, cell genome and their involvement in cancer (Review)

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    The chemical nature of most of the mycotoxins makes them highly liposoluble compounds that can be absorbed from the site of exposure such as from the gastrointestinal and respiratory tract to the blood stream where it can be dissimilated throughout the body and reach different organs such as the liver and kidneys. Mycotoxins have a strong tendency and ability to penetrate the human and animal cells and reach the cellular genome where it causes a major mutagenic change in the nucleotide sequence which leads to strong and permanent defects in the genome. This defect will eventually be transcribed, translated and lead to the development of cancer. In this review, the chemical and physical nature of mycotoxins, the action of mycotoxins on the cellular genome and its effect on humans, mycotoxins and their carcinogenicity and mycotoxins research gaps are discussed, and new research areas are suggested. The research review posed various questions. What are the different mycotoxins that can cause cancer, what is the role of mycotoxins in causing cancer and what types of cancers can be caused by mycotoxins? These questions have been selected due to the significant increase in the mycotoxin contamination and the cancer incidence rate in the contemporary world. By revealing and understanding the role of mycotoxins in developing cancer, measures to reduce the risks and incidents of cancer could be taken
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