检索结果-南通市图书馆

Nuclear Science and Techniques 2016年第2期27卷 106-114页

作者： G.r.Ansarifar H.r.Akhavan Department of Nuclear Engineering Faculty of Advanced Sciences and Technologies University of Isfahan

This paper presents findings on the sliding mode controller for a nuclear reactor. One of the important operations in nuclear power plants is load following. In this paper, a sliding mode control system, which is a robust nonlinear controller, is designed to control the pressurizedwater reactor power. The reactor core is simulated based on the point kinetics equations and six delayed neutron groups. Considering neutron absorber poisons and regarding the limitations of the xenon concentration measurement, a sliding mode observer is designed to estimate its value, and finally, a sliding mode control based on the sliding mode observer is presented to control the core power of reactor. The stability analysis is given by means Lyapunov approach; thus, the control system is guaranteed to be stable within a large range. The employed method is easy to implement in practical applications, and moreover,the sliding mode control exhibits the desired dynamic properties during the entire output-tracking process independent of perturbations. Simulation results are presented to demonstrate the effectiveness of the proposed observerbased controller in terms of performance, robustness and stability.

关键词：鲁棒非线性控制滑模观测器核反应堆估计氙气气浓度非线性鲁棒控制器滑模控制系统

High-Velocity Projectile Impact Behaviour of Friction Stir Welded AA7075 Thick Plates

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2023年第11期29卷 153-163页

作者： r.Praveen S.r.Koteswara rao G.Selvakumar r.Damodaram Department of robotics and Automation Karpaga Vinayaga College of Engineering and TechnologyChengalpattu603308TamilNaduIndia Department of Mechanical Engineering Sri Sivasubramaniya Nadar College of EngineeringChennai603110TamilNaduIndia

In this study, high velocity impact behaviour of friction stir welded AA7075-T651 25 mm thick plates were investigated using a 7.62 mm × 51 mm lead core and 7.62 mm × 39 mm steel core projectiles. Prior to ballistic trails, mechanical and metallurgical properties of friction stir welded AA 7075-T651 25 mm thick plates were studied. Microstructural and hardness studies revealed that friction stir welds constituted three distinct regions namely Weld Nugget(WN), Thermo-Mechanically Affected Zone(TMAZ) and Heat Affected Zone(HAZ). Base Material(BM) and all three weld regions were ballistically tested as per military standard NIJ.0108.01 using lead and steel core bullets at maximum permissible velocities of 830 ± 20 and 700 ± 30 m/s, respectively. It has been found that base material(AA7075-T651)and all three weld regions of 25 mm thick plates were able to resist perforation by both types of projectiles used. However depth of penetration has been found to increase from BM to WN, HAZ and TMAZ for both types of projectiles. In all cases steel core projectiles caused higher depth of penetration compared to those caused by lead core projectiles. TMAZs of the friction stir welds were found to be the weakest zone. The fracture that occurred in the base material was spall fragmentation indicating brittle failure, whereas all zones of friction stir welded AA7075-T651 targets with a front petalling, indicating ductile failure. The post-ballistic tested samples showed no significant change in the microstructure of the BM and WN. On the other hand, TMAZ and HAZ showed severe grain deformation in the direction of projectile penetration, and the formation of adiabatic shear bands(ASB). This work showed that 25 mm thick friction stir welded AA7075-T651 joints responded well to ballistic impact loads, making them a good choice for light combat vehicles.

关键词： Aluminum alloy Thick plate Friction stir welding Ballistic performance Depth of penetration

STUDY OF THrEE-DIMENSIONAL SEPArATION OF BOUNDArY LAYEr OVEr BLUNT BODIES

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2009年第1期21卷 100-107页

作者： ATMANI r. BrIMA A. ASKOVIC r. Laboratoire de mécanique des fluides Université de ValenciennesAulnoy lez Valenciennes 59326 France Département de Mécanique Université de BiskraBiskra 07000 Algérie

In the case of three-dimensional flows, the separation can be defined in more than one way. Discussions about three-dimensional boundary layer separation in the literature have found a rational extension of the zero skin friction. Attempts have been made to establish the identity of “separation lines”. Among definitions, these may be found：（1） envelopes of limiting streamlines, （2） lines dividing flow which has come from different regions, （3） lines of singularities （problems of topology）, （4） lines on which some component of the skin friction vanishes. Each of these is valid under certain conditions, but none is universally valid. In the present work, we use the definition （4）, i.e. at low incidence of a blunt body the separation line is identified as the zero of the meridian skin friction component （Wang 1975）. So the separation line on a flattened spheroid （6：3：1） at 6° of incidence is calculated, as well as experimentally determined by using the electrochemical method, which allows to follow the evolution of the parietal velocity gradient.

关键词： three-dimensional flows separation boundary layers blunt bodies

Fully developed forced convection through semi-elliptic ducts

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2016年第1期37卷 37-44页

作者： r.ALASSAr Department of Mathematics and Statistics King Fahd University of Petroleum and Minerals

An exact solution of the problem of fully developed forced convection through semi-elliptic ducts is obtained under constant axial heat flux and peripherally uniform temperature. The solution is validated by comparing... 详细信息

关键词： convection semi-elliptic duct

Heminephrectomy for a large renal mass in a horseshoe kidney: A case report outlining a robotic assisted laparoscopic approach

在线全文

学校读者我要写书评

暂无评论

Laparoscopic, Endoscopic and robotic Surgery 2022年第2期5卷 78-81页

作者： Matthew Mancuso benjamin B.Beech David W.Chapman Blair St Martin Faculty of Medicine and Dentistry University of AlbertaEdmontonT6G 2R7Canada Division of Urology Department of SurgeryUniversity of AlbertaEdmontonT6G 2R7Canada

With an incidence of 1/500,a horseshoe kidney is not *** discovered in horseshoe kidney however are quite rare,and prove difficult to surgically manage due to complex vascular *** variable surgical approaches previously described,only a select few robot-assisted cases have been *** case describes one such robot-assisted laparoscopic heminephrectomy,with the use of indocyanine green and an endovascular stapler to successfully demarcate ischemia and achieve hemostasis *** complications were encountered,and pathology revealed a pT1bN0 clear cell renal cell carcinoma with negative surgical margins,demonstrating the feasibility of our approach.

关键词： Horseshoe kidney robot-assisted Laparoscopic Partial nephrectomy Tumour

Magnetocaloric and magnetic properties of La_2NiMnO_6 double perovskite

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2016年第8期25卷 373-378页

作者： Masrour r Jabar A Laboratory of Materials Processes Environment and Quality Cady Ayyed University National School of Applied Sciences

The magnetic effect and the magnetocaloric effect in La_2NiMnO_6（LNMO） double perovskite are studied using the Monte Carlo *** magnetizations,specific heat values,and magnetic entropies are obtained for different exchange interactions and external magnetic *** adiabatic temperature is *** transition temperature is *** relative cooling power is established with a fixed value of exchange *** to the master curve behaviors for the temperature dependence of △S_m^（max） predicted for different maximum fields,in this work it is confirmed that the paramagnetic-ferromagnetic phase transition observed for our sample is of a second *** near room-temperature interaction and the superexchange interaction between Ni and Mn are shown to be due to the ferromagnetism of LNMO.

关键词： oxides magnetocaloric Monte Carlo simulation specific heat magnetic properties

Value enhancement of olivine process dust through air classification

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2012年第3期19卷 185-191页

作者： r.A.Kleiv Department of Geology and Mineral resources Engineering Norwegian University of Science and TechnologySem Slandsvei 1N-7491 TrondheimNorway

As a result of the production of dry olivine sand products at A/S Olivin＇s production plant at Aheim in western Norway, an annual quantity of some 20000-30000 t of process dust is produced. The bulk of this material is currently being sold as a slag conditioner at a rela- tively low price; hence, alternative uses of the process dust are now being sought. Information regarding the chemical composition of the material as a function of particle size facilitates product modifications through exclusion or mixing of individual size fractions. This paper demonstrates how such information can be obtained from air classification experiments when these are combined with chemical analysis of the produced size fractions. The classification and subsequent analysis of the olivine process dust revealed that the finer size fractions had high loss on ignition （LOI） values and were relatively low in MgO when compared with the bulk analysis. removal of the finer fractions re- sulted in a remaining coarse product of significantly higher quality. The coarse material could be used as a raw material for further processing; it could be recycled or it could constitute a new product in itself.

关键词： olivine air classification dust product development

rosuvastatin‑Eluting Gold‑Nanoparticle‑Loaded Perivascular Wrap for Enhanced Arteriovenous Fistula Maturation in a Murine Model

在线全文

学校读者我要写书评

暂无评论

Advanced Fiber Materials 2023年第6期5卷 1986-2001页

作者： Carleigh Klusman benjamin Martin Joy Vanessa D.Perez Allan John r.Barcena Marvin r.Bernardino Erin Marie D.San Valentin Jossana A.Damasco Huckie C.Del Mundo Karem A.Court Biana Godin Gino Martin Canlas Natalie Fowlkes richard Bouchard Jizhong Cheng Steven Y.Huang Marites P.Melancon Department of Interventional radiology The University of Texas MD Anderson Cancer CenterHouston 77030USA Baylor College of Medicine Houston 77030USA College of Medicine University of the Philippines Manila1000 ManilaPhilippines Department of Nanomedicine Houston Methodist Research InstituteHouston 77030USA Department of Chemistry Lamar UniversityBeaumont 77710USA Department of Veterinary Medicine and Surgery The University of Texas MD Anderson Cancer CenterHouston 77030USA Department of Imaging Physics The University of Texas MD Anderson Cancer CenterHouston 77030USA Section of Nephrology Department of MedicineSelzman Institute for Kidney HealthBaylor College of MedicineHouston 77030USA The University of Texas MD Anderson Cancer Center UTHealth Houston Graduate School of Biomedical Sciences Houston 77030USA

Arteriovenous fistulas(AVFs)are a vital form of AV access for patients requiring hemodialysis,but they link to overall morbidity and mortality when they fail to *** most common cause of AVF non-maturation is neointimal hyperplasia(NIH).To minimize the deleterious effects of NIH,a perivascular wrap composed of polycaprolactone(PCL),rosuvastatin(rOSU),and gold nanoparticles(AUNPs)was *** study assessed the impact of rOSU-eluting,radiopaque resorbable perivascular wraps on pathologic NIH in a chronic kidney disease(CKD)rodent model of *** PCL wraps containing AuNPs and/or rOSU were monitored for in vitro tensile strength,AuNP release,rOSU elution,and effect on cellular *** wraps were then implanted around an AVF in a CKD rodent model for in vivo ultrasound(US)and micro-computed tomography(mCT)*** specimens were collected for histological *** viability was preserved in the presence of both AuNP-and rOSU-containing *** vitro release of rOSU and AuNPs correlated with in vivo findings of decreasing radiopacity on mCT over ***-loaded wraps had higher radiopacity(1270.0-1412.0 HU at week 2)compared with other wraps(103.5-456.0 HU),which decreased over *** addition of rOSU decreased US and histologic measurements of *** reduced NIH seen with rOSU-loaded perivascular wraps suggests a synergistic effect between mechanical support and anti-hyperplasia ***,AuNP loading increased wrap ***,our results show that AuNP-and rOSU-loaded PCL wraps induce AVF maturation and suppress NIH while facilitating optimal implanted device visualization.

关键词： Arteriovenous fistula Chronic kidney disease Nanoparticles Polycaprolactone radiopacity rosuvastatin

Development and characterization of stainless steel fiber-based copper-free brake liner formulation:A positive solution for steel fiber replacement

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Friction 2020年第2期8卷 396-420页

作者： Vijay r D.Lenin SINGArAVELU r.JAYAGANTHAN Department of Production Engineering National Institute of TechnologyTiruchirappalli 620015Tamil NaduIndia Department of Engineering Design Indian Institute of Technology MadrasChennai 600036Tamil NaduIndia

This study deals with the development of drum brake liner for a multi-utility vehicle possessing a hydraulic brake system by varying 7 weight%of steel fiber and stainless steel fiber each,in friction composite *** developed friction composites were tested for physical,chemical,corrosion,mechanical,thermal properties,and tribological characteristics,under near-actual conditions using an inertia dynamometer as per industrial *** element analysis software(ANSYS)analysis was performed to show the thermal stress distribution of the developed friction composites at the maximum temperature rise due to heat generated during brake stops,and an extensive evaluation method was used to rank the *** study concludes that the brake factor of the stainless steel fiber-based friction composite produces stable performance in all conditions with a lower liner temperature rise of 340°C and lower thermal stress at 4.255294 ***,the steel fiber-based composites produced high performance at the beginning but deteriorated after a certain period due to higher levels of corrosion and a high temperature rise of 361°C resulting in a negative fade(-0.84%)and more thermal stress(5.619102 MPa).The primary plateau,secondary plateau,back transfer of drum wear debris,and the distribution of constituents on the worn surface of the developed composites in a resin matrix were identified and studied using a scanning electron microscope(SEM)equipped with energy-dispersive spectroscopy.

关键词： stainless steel fiber steel fiber brake liner friction composite