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A numerical optimization of high altitude testing facility for wind tunnel experiments

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chinese journal of Aeronautics 2015年第3期28卷 636-648页

作者： j.Bruce Ralphin Rose G.R.jinu c.j.Brindha department of Aeronautical Engineering Regional Centre of Anna University department of Mechanical Engineering University College of EngineeringNagercoil department of Aeronautical Engineering The Raajas Engineering College

Abstract High altitude test facilities are required to test the high area ratio nozzles operating at the upper stages of rocket in the nozzle full flow conditions. It is typically achieved by creating the ambient pressure equal or less than the nozzle exit pressure. On average, air/GN2 is used as active gas for ejector system that is stored in the high pressure cylinders. The wind tunnel facilities are used for conducting aerodynamic simulation experiments at/under various flow velocities and operating conditions. However, constructing both of these facilities require more laboratory space and expensive instruments. Because of this demerit, a novel scheme is implemented for conducting wind tunnel experiments by using the existing infrastructure available in the high altitude testing （HAT） facility. This article presents the details about the methods implemented for suitably modifying the sub-scale HAT facility to conduct wind tunnel experiments. Hence, the design of nozzle for required area ratio A/A＊, realization of test section and the optimized configuration are focused in the present analysis. Specific insights into various rocket models including high thrust cryogenic engines and their holding mechanisms to conduct wind tunnel experiments in the HAT facility are analyzed. A detailed cFD analysis is done to propose this conversion without affecting the existing functional requirements of the HAT facility.

关键词： cFD Enclosed free-jet section Ground testing High altitude testing (HAT)facility Optimization

Molecular level simulations on multi-component systems --a morphology prediction method

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Frontiers of chemical Science and Engineering 2013年第1期7卷 49-54页

作者： c. ScHMIDT j. ULRIcH center for Engineering Science Thermal Process Engineering Martin Luther University Halle-Wittenberg D-06099 Halle (Saale) Germany

The crystal morphology grown from a solution composed of an organic solvent, solute and additive can be predicted reliably by a computational method. Modeling the supersaturated solution as liquid phase is achieved by employing commercial software. The molecular composition of this solution is a required input parameter. The face specific diffusion coefficient of the solid （crystal surface） and liquid （solution） system is determined using the molecular dynamics procedure. The obtained diffusion coefficient is related to the specific face growth rate via the attachment energy of the pure morphology. The significant improvements are achieved in the morphology prediction because the investigation on the face growth rates in a complex growth environment （as multi-component solutions with additives） can be carried out based on the diffusion coefficients.

关键词： crystallization morphology molecular dynamics solution

Numerical study of flow and heat transfer during oscillatory blood flow in diseased arteries in presence of magnetic fields

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Applied Mathematics and Mechanics(English Edition) 2012年第5期33卷 649-662页

作者： A.SINHA j.c.MISRA School of Medical Science and Technology Indian Institute of TechnologyKharagpur 721302India department of Mathematics Institute of Technical Education and ResearchSiksha O Anusandhan UniversityBhubaneswar 751030India

A problem motivated by the investigation of the heat and mass transfer in the unsteady magnetohydrodynamic （MHD） flow of blood through a vessel is solved numerically when the lumen of the vessel has turned into the porous structure. The time-dependent permeability and the oscillatory suction velocity are considered. The computational results are presented graphically for the velocity, the temperature, and the concentration fields for various values of skin friction coefficients, Nusselt numbers, and Sherwood numbers. The study reveals that the flow is appreciably influenced by the presence of a magnetic field and also by the value of the Grashof number.

关键词： mass transfer radiation suction velocity skin-friction

Sphincter preservation for distal rectal cancer - a goal worth achieving at all costs?

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World journal of Gastroenterology 2011年第7期17卷 855-861页

作者： jürgen Mulsow des c Winter Institute for clinical Outcomes Research and Education St. Vincent’s University Hospital

To assess the merits of currently available treatment options in the management of patients with low rectal cancer, a review of the medical literature pertaining to the operative and non-operative management of low rectal cancer was performed, with particular emphasis on sphincter preservation, oncological outcome, functional outcome, morbidity, quality of life, and patient preference. Low anterior resection (AR) is technically feasible in an increasing proportion of patients with low rectal cancer. The cost of sphincter preservation is the risk of morbidity and poor functional outcome in a significant proportion of patients. Transanal and endoscopic surgery are attractive options in selected patients that can provide satisfactory oncological outcomes while avoiding the morbidity and functional sequelae of open total mesorectal excision. In complete responders to neo-adjuvant chemoradiotherapy, a non-operative approach may prove to be an option. Abdominoperineal excision (APE) imposes a permanent stoma and is associated with significant incidence of perineal morbidity but avoids the risk of poor functional outcome following AR. Quality of life following AR and APE is comparable. Given the choice, most patients will choose AR over APE, however patients following APE positively appraise this option. In striving toward sphincter preservation the challenge is not only to achieve the best possible oncological outcome, but also to ensure that patients with low rectal cancer have realistic and accurate expectations of their treatment choice so that the best possible overall outcome can be obtained by each individual.

关键词： Rectal cancer Survival Local recurrence Morbidity Anorectal function Quality of life Patient preference

Transhiatal versus transthoracic esophagectomy for esophageal cancer

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World journal of Gastroenterology 2010年第30期16卷 3804-3810页

作者： j camilo Barreto Mitchell c Posner Section of General Surgery and Surgical Oncology Department of SurgeryUniversity of Chicago Pritzker School of Medicine5841 S. Maryland AveMC 5094ChicagoIL 60637United States

Esophageal cancer continues to represent a formidable challenge for both patients and clinicians. Relative 5-year survival rates for patients have improved over the past three decades, probably linked to a combination of improved surgical outcomes, progress in systemic chemotherapy and radiotherapy, and the increasing acceptance of multimodality treatment. Surgical treatment remains a fundamental component of the treatment of localized esophageal adenocarcinoma. Multiple approaches have been described for esophagectomy, which can be thematically grouped under two major categories: either transthoracic or transhiatal. The main controversy rests on whether a more extended resection through thoracotomy provides superior oncological outcomes as opposed to resection with relatively limited morbidity and mortality through a transhiatal approach. After numerous trials have addressed these issues, neither approach has consistently proven to be superior to the other one, and both can provide excellent short-term results in the hands of experienced surgeons. Moreover, the available literature suggests that experience of the surgeonand hospital in the surgical management of esophageal cancer is an important factor for operative morbidity and mortality rates, which could supersede the type of approach selected. Oncological outcomes appear to be similar after both procedures.

关键词： Esophageal cancer Transhiatal esophageal resection Transthoracic esophageal resection

AMP-activated kinase in human spermatozoa： identification, intracellular localization, and key function in the reRulation of sperm motility

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Asian journal of Andrology 2017年第6期19卷 707-714页

作者： Violeta calle-Guisado Ana Hurtado de Llera David Martin-Hidalgo jose Mijares Maria c Gil Ignacio S Alvarez Maria j Bragado Luis j Garcia-Marin Research Group of Intracellular Signalling and Technology of Reproduction (SINTREP) School of Veterinary Medicine University of Extremadura Caceres Spain Assisted Reproduction Unit at the-Minimally Invasive surgery center jesos Uson (ccMIjU) caceres Spain Norba clinic Caceres Spain Research Group of Reproduction and Embryo development (REdeS) University of Extremadura Badajoz Spain Extremadura Institute of Assisted Reproduction (IERA) Badajoz Spain.

AMP-activated kinase （AMPK）, a protein that regulates energy balance and metabolism, has recently been identified in boar spermatozoa where regulates key functional sperm processes essential for fertilization. This work＇s aims are AMPK identification, intracellular localization, and their role in human spermatozoa function. Semen was obtained from healthy human donors. Sperm AMPK and phospho-Thr172-AMPK were analyzed by Western blotting and indirect immunofluorescence. High- and low-quality sperm populations were separated by a 40%-80% density gradient. Human spermatozoa motility was evaluated by an Integrated Semen Analysis System （ISAS） in the presence or absence of the AMPK inhibitor compound c （cc）. AMPK is localized along the human spermatozoa, at the entire acrosome, midpiece and tail with variable intensity, whereas its active form, phospho-Thr172-AMPK, shows a prominent staining at the acrosome and sperm tail with a weaker staining in the midpiece and the postacrosomal region. Interestingly, spermatozoa bearing an excess residual cytoplasm show strong AMPK staining in this subcellular compartment. Both AMPK and phospho-Thr172-AMPK human spermatozoa contents exhibit important individual variations. Moreover, active AMPK is predominant in the high motility sperm population, where shows a stronger intensity compared with the low motility sperm population. Inhibition of AMPK activity in human spermatozoa by cc treatment leads to a significant reduction in any sperm motility parameter analyzed： percent of motile sperm, sperm velocities, progressivity, and other motility coefficients. This work identifies and points out AMPK as a new molecular mechanism involved in human spermatozoa motility. Further AMPK implications in the clinical efficiency of assisted reproduction and in other reproductive areas need to be studied.

关键词： AMP-activated kinase human spermatozoa immunolocalization sperm motility sperm quality

Stability of steel thixoforming process

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中国有色金属学会会刊：英文版 2010年第S3期20卷 937-942页

作者： j.c.PIERRET A.RASSILI G.VANEETVELD j.LEcOMTE-BEcKERS ThixoUnit ULg Material Sciences UnitDepartment of Aerospace and Mechanical EngineeringUniversity of Liège

To improve the industrialization of the process,the study of a thixoforming line stability was *** thixoforming line is fully automated to optimize the repeatability of the *** of the heating cycle,the slug temperature,the tool temperature and the forming speed were *** each of them,a range of the expected variations in a steady-state process as well as the effects of these variations on the process itself(forming load and parts quality) were *** variations are shown to be *** different tools were used in the *** mathematical simulations were realized on the finite elements code Forge2008with a semi-solid constitutive *** capacity of the model to represent the process stability was *** simulation results are in agreement with the experiment results.

关键词： thixoforming steel high melting point stability robustness process

conception of tooling adapted to thixoforging of high solid fraction hot-crack-sensitive aluminium alloys

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Transactions of Nonferrous Metals Society of china 2010年第9期20卷 1712-1718页

作者： G.VANEETVELD A.RASSILI j.c.PIERRET j.LEcOMTE-BEcKERS Thixo Unit B56University of Liège Special Metallic Materials B52University of Liège

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.7<φs<1), which involves the processing of alloys in the semi-solid *** has to be adapted to this particular process to benefit shear thi... 详细信息

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.7ch involves the processing of alloys in the semi-solid *** has to be adapted to this particular process to benefit shear thinning and thixotropic behaviour of such semi-solid *** parameters, such as the forming speed and tool temperature, have to be accurately controlled because of their influence on thermal exchanges between material flow and *** thermal exchanges influence the high-cracking tendency and the rheology of the semi-solid material during forming, which affects parts properties and therefore their *** tests show how thermal exchanges influence quality of thixoforged parts made of 7075 aluminium alloys at high solid fraction by modifying process parameters like forming speed, tool temperature and tool thermal *** an optimum in terms of thermal exchanges has to be found between surface quality and mechanical properties of the part.A direct application is the evaluation of surface quality of thixoforged thin wall parts made of 7075 aluminium alloy.

关键词： thixoforging solid fraction near-net-shaping tooling 7075 aluminium alloys

Multistage serrated flow behavior of a medium-manganese high-carbon steel

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journal of Iron and Steel Research International 2020年第9期27卷 1064-1072页

作者： j.chen Y.Zhang j.j.Wang c.M.Liu S.X.Zhao Key Laboratory for Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819LiaoningChina Shenyang Industrial Transformation Upgrading Promotion center Shenyang 110083LiaoningChina The State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819LiaoningChina School of Materials Science and Engineering Northeastern UniversityShenyang 110819LiaoningChina central Research Institute Baoshan Iron&Steel Co.Ltd.Shanghai 201999China

The deformation mechanisms and the flow stress behavior of a medium-manganese high-carbon steel during cold deformation at a strain rate of 10×5 s^-1 were explored using a universal testing machine,an X-ray diffractometer,a field emission scanning electron microscope and a high-resolution transmission electron *** results show that continuous step-up serrated flow behavior appears after the yielding point,and the true stress-strain curve is roughly divided into five stages based on distinctive densities and amplitudes of *** strengthening mechanisms of the experimental steel involve cottrell atmosphere,twinning-induced plasticity(TWIP)efect and transformation-induced plasticity(TRIP)*** effect is the dominant deformation mechanism,and deformation twins formed by TWIP effect comprise primary,secondary and ***,TRIP effect arises in the local high-strain *** element plays a key role in the transformation of the deformation mechanism.A small amount of carbide precipitates around twin boundaries lead to the formation of local carbon-poor regions,and Md temperature and stacking fault energy of medium-manganese high-carbon steel are propitious to the occurrence of TRIP *** addition,the contributions of various deformation mechanisms to plasticity are calculated,and that of TWIP effect is the greatest.

关键词： Serrated flow deformation mechanism deformation twin Twinning-induced plasticity Transformation-induced plasticity