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Developed Numerical Simulation of Falling and Moving Objects in Viscous Fluids under the Action of a Reynolds Lubrication Theory and Low Reynolds Numbers

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Open Journal of Fluid Dynamics 2020年第1期10卷 8-30页

作者： Seema Paul jesper Oppelstrup Department of Scientific Computing Royal Institute of Technology Stockholm Sweden Department of Sustainable Development Environmental Science and Engineering Royal Institute of Technology Stockholm Sweden

The development work focuses on the numerical simulations of free body movement in viscous fluid. The aim is to make the simulation of very slow motion of the small body in viscous fluid. We developed bodies’ immersed dynamics simulations in viscous fluid by seeking numerical solutions for appropriate field variables. We developed the methods for vertically and spherically cylindrical objects’ motions, the forces on bodies close to a plane stationary wall are computed from the velocity and pressure fields using the Stokes equation through COMSOL Multiphysics finite element software. The Navier-Stokes equation is reduced to Stokes equation there is independence of time which means object will have an effect only on the motion and the slightly compressible flow assumption is made in order to obtain smooth solution numerically. The forces on an object in slightly compressible Stokes flow have been exerted on the falling objects. The resulting forces have compared with analytical results from the Reynolds Lubrication Theory, and achieved significant results from the development method in Matlab and achieved significant numerical simulations in COMSOL. In addition, an investigation has been made to an object swimming at low Reynolds number. At low Reynolds number moving is possible when object scale is small and flow pattern is slow and sticky. We have developed a system for a thin two-dimensional (2D) worm-like object wiggle that is passing a wave along its centreline and its motion has simulated by the Ordinary Differential Equations (ODE) system and by the Arbitrary Lagrangian-Eulerian (ALE) moving mesh technology. The development method result shows that it is possible for the small object to have a motion from one position to another through small amplitudes and wavelengths in viscous fluid.

关键词： Slightly Compressible Stokes Equation Reynolds Lubrication Theory Falling and Moving Objects Moving Mesh Low Reynold Swimming

Nonlinearity-tailored fiber laser technology for low-noise, ultra-wideband tunable femtosecond light generation

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Photonics Research 2017年第6期5卷 262-273页

作者： XIAOMIN LIU jesper LAEGSGAARD ROMAN IEGOROV ASK S.SVANE F.OMER ILDAY HAOHUA TU STEPHEN A.BOPPART DMITRY TURCHINOVICH DTU Fotonik Technical University of Denmark Max Planck Institute for Polymer Research Department of Physics Bilkent University National Research Tomsk Polytechnic University Institute of Power Engineering Department of Electrical and Electronics Engineering Bilkent University Biophotonics Imaging Laboratory University of Illinois at Urbana-Champaign Fakultat fur Physik Universitat Duisburg-Essen

The emission wavelength of a laser is physically predetermined by the gain medium used. Consequently, arbitrary wavelength generation is a fundamental challenge in the science of light. Present solutions include optical parametric generation, requiring complex optical setups and spectrally sliced supercontinuum, taking advantage of a simpler fiber technology: a fixed-wavelength pump laser pulse is converted into a spectrally very broadband output, from which the required resulting wavelength is then optically filtered. Unfortunately, this process is associated with an inherently poor noise figure, which often precludes many realistic applications of such supercontinuum sources. Here, we show that by adding only one passive optical element—a tapered photonic crystal fiber—to a fixed-wavelength femtosecond laser, one can in a very simple manner resonantly convert the laser emission wavelength into an ultra-wide and continuous range of desired wavelengths, with very low inherent noise, and without mechanical realignment of the laser. This is achieved by exploiting the double interplay of nonlinearity and chirp in the laser source and chirp and phase matching in the tapered fiber. As a first demonstration of this simple and inexpensive technology, we present a femtosecond fiber laser continuously tunable across the entire red–green–blue spectral range.

关键词： length PCF Nonlinearity-tailored fiber laser technology for low-noise ultra-wideband tunable femtosecond light generation

In Situ Etching for Total Control Over Axial and Radial Nanowire Growth

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Nano Research 2010年第4期3卷 264-270页

作者： Magnus T.Borgström jesper Wallentin Johanna Trägårdh Peter Ramvall Martin Ek LReine Wallenberg Lars Samuelson Knut Deppert Solid State Physics Lund UniversityBox 118S-22100LundSweden Polymer&Materials Chemistry/nCHREM Lund UniversityS-22100 LundSweden H.H.Wills Physics Laboratory University of BristolTyndall AvenueBristol BS81TLUnited Kingdom

We report a method using in situ etching to decouple the axial from the radial nanowire growth pathway,independent of other growth *** a wide range of growth parameters can be explored to improve the nanowire properties without concern of tapering or excess structural defects formed during radial *** demonstrate the method using etching by HCl during InP nanowire *** improved crystal quality of etched nanowires is indicated by strongly enhanced photoluminescence as compared to reference nanowires obtained without etching.

关键词： MOVPE nanowire growth in situ etching photoluminescence

WARA-PS:a research arena for public safety demonstrations and autonomous collaborative rescue robotics experimentation

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Autonomous Intelligent Systems 2021年第1期1卷 104-134页

作者： Olov Andersson Patrick Doherty Mårten Lager Jens-Olof Lindh Linnea Persson Elin A.Topp jesper Tordenlid Bo Wahlberg Department of Computer and Information Science Linköping UniversityLinköpingSweden Saab Kockums MalmöSweden Division of Decision and Control Systems School of Electrical Engineering and Computer ScienceKTH Royal Institute of TechnologyStockholmSweden Department of Computer Science Lund UniversityLundSweden Saab Combitech AB LinköpingSweden Division of Automatic Control Department of Electrical EngineeringLinköping UniversityLinköpingSweden

A research arena(WARA-PS)for sensing,data fusion,user interaction,planning and control of collaborative autonomous aerial and surface vehicles in public safety applications is *** objective is to demonstrate scientific discoveries and to generate new directions for future research on autonomous systems for societal *** enabler is a computational infrastructure with a core system architecture for industrial and academic *** includes a control and command system together with a framework for planning and executing tasks for unmanned surface vehicles and aerial *** motivating application for the demonstration is marine search and rescue operations.A state-of-art delegation framework for the mission planning together with three specific applications is also *** first one concerns model predictive control for cooperative rendezvous of autonomous unmanned aerial and surface *** second project is about learning to make safe real-time decisions under uncertainty for autonomous vehicles,and the third one is on robust terrain-aided navigation through sensor fusion and virtual reality tele-operation to support a GPS-free positioning system in marine *** research results have been experimentally evaluated and demonstrated to industry and public sector audiences at a marine test *** would be most difficult to do experiments on this large scale without the WARA-PS research ***,these demonstrator activities have resulted in effective research dissemination with high public visibility,business impact and new research collaborations between academia and industry.

关键词： Autonomous systems Intelligent system architectures Research demonstration arena Autonomous drones Autonomous marine vessels Public safety and security Collaborative robotics

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作物相对水分利用效率与理论节水潜力

水科学进展 2019年第5期30卷 682-690页

作者：代小平周雯晶韩宇平窦明冯吉 Svensson jesper 华北水利水电大学水利学院河南郑州450046 河南省节水农业重点实验室河南郑州450046 黄河勘测规划设计研究院有限公司河南郑州450003 水资源高效利用与保障工程河南省协同创新中心河南郑州450046 郑州大学水利科学与工程学院河南郑州450001 Smith School of Enterprise and the Environment University of OxfordOxford OX13QY

作物水分利用效率是评价农业用水效率的重要指标,由于气候差异,采用作物水分利用效率评价不同区域的用水效率可能存在一定误差,尚缺乏深入研究。基于潜在水分利用效率指标和气象数据,计算了2014年中国小麦、玉米和水稻在充分灌溉条件下... 详细信息

作物水分利用效率是评价农业用水效率的重要指标,由于气候差异,采用作物水分利用效率评价不同区域的用水效率可能存在一定误差,尚缺乏深入研究。基于潜在水分利用效率指标和气象数据,计算了2014年中国小麦、玉米和水稻在充分灌溉条件下的潜在水分利用效率,分析了区域气候差异对作物水分利用效率的影响,提出了相对水分利用效率和理论节水潜力的概念和计算方法,并进行了实例研究。结果表明:各类作物在不同站点的潜在水分利用效率的标准差为0.49~1.01 kg/m 3,多数作物潜在水分利用效率的空间差异大于实际水分利用效率的空间差异;主要作物的平均相对水分利用效率为50.7%,其理论节水潜力为884.8~4 064.5 m 3/hm 2;作物水分利用效率和广义节水潜力指标可能高估或低估作物的用水效率和节水潜力。研究认为在比较区域间作物的水分利用效率时不能忽略气候差异的影响;由于考虑了区域气候差异,相对水分利用效率和理论节水潜力指标更合理。

关键词：相对水分利用效率理论节水潜力粮食作物

Relationship between heavy metals and clay mineralogy of the modern sediment of salt marsh at the east coast of Wadden Sea, Denmark

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Chinese Journal Of Geochemistry 2006年第B8期25卷 172-173页

作者： Christian Christiansen jesper Bartholdy Institute of Geography University of Copenhagen Denmark

The Natural Forest Protection Program in China： A Contingent Valuation Study in Heilongjiang Province

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Journal of Environmental Science and Engineering(B) 2012年第3期1卷 426-432页

作者： Frida Edstrom Hanna Nilsson jesper Stage Department of Economies University of Gothenburg Gothenburg 40530 Sweden Department of Social Sciences Mid Sweden University Sundsval185170 Sweden

In 1998, the Chinese Government implemented the NFPP (Natural Forest Protection Program), which included logging restrictions, protected areas, replanting, and a range of other policies aimed at safeguarding the state of the country"s forests and reducing the risk of erosion and flooding. A second phase of this program is currently being discussed. In this paper, contingent valuation is used to estimate the WTP (willingness to pay) for maintaining the program among the inhabitants in Heilongjiang Province in northern China. The results show that, even with fairly conservative assumptions, the aggregated WTP for maintaining the program for another five years is some 3.24 billion yuan per year. This can be compared with the current cost of the Program in the province, which is some 1.57 billion yuan per year.

关键词：天然林保护工程黑龙江省中国政府估值洪水风险水土流失支付意愿中国北部

Short-term postoperative discomfort in patients receiving flapless contra open implant surgery

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Open Journal of Stomatology 2013年第5期3卷 298-305页

作者： Alexander Aizenberg jesper Jansson Peter Abrahamsson Department of Oral and Maxillofacial Surgery and Oral Medicine Faculty of OdontologyMalmo UniversityMalmoSweden Maxillofacial Unit Halmstad HospitalHalmstadSweden

Purpose: The aim of this pilot study was to evaluate subjective and objective findings on short-term post-operative discomfort in patients receiving flapless implant surgery compared to traditional open flap surgery. Materials and Methods: A two-centre, prospective survey study was conducted, using a customized questionnaire. Between December 2010 and January 2012, 20 patients were consecutively included. Eleven received conventional open-flap surgery and nine received flapless surgery. Inflammatory signs, analgesic consumption and sleeping difficulties were evaluated up to seven days postoperatively. A clinical examination was made one week postoperatively. Results: Significantly less experienced swelling was noted 24 hours after flapless surgery compared to open flap surgery for patients receiving four implants or more, and at three days postoperatively for patients receiving single implants. No difference concerning sleeping difficulties, pain or analgesic consumption was found. Clinical examination one week postoperatively showed no differences in wound gaps, redness of the mucosa, or presence of pus between the groups. Conclusions: In conclusion, flapless surgery seems to have a limited effect on postoperative comfort and short-term post-operative signs of soft tissue healing compared to open flap surgery. There is a need for larger randomized trials for evaluating differences in postoperative discomfort between the two surgical techniques.

关键词： Postoperative Discomfort Flapless Surgery Guided Implant Surgery

Effects of 3 months of full-court and half-court street basketball training on health profile in untrained men

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Journal of Sport and Health Science 2018年第2期7卷 132-138页

作者： Morten B.Randers Marie Hagman Jonathan Brix jesper F.Christensen Mogens T.Pedersen Jens J.Nielsen Peter Krustrup Department of Sports Science and Clinical Biomechanies SDU Sport and Health Sciences Cluster (SHSC) University of Southern Denmark Odense 5230 Denmark Department of Nutrition Exercise and Sports University of Copenhagen Copenhagen 2200 Denmark Centre oflnflammation and Metabolism (CIM) and Centre for Physical Activity Research (CFAS) Rigshospitalet Faculty of Health Science Copenhagen University Hospital 7641 University of Copenhagen Copenhagen 2100 Denmark Sport and Health Sciences University of Exeter Exeter EX1 2LU UK

Purpose: The aim of the present study was to investigate whether street basketball organized as 3 v 3 on either a half court(HC) with 1 basket or a full court(FC) with 2 baskets could improve fitness and health profiles of untrained men after 3 months of supervised ***: Thirty-five untrained men(aged 20—42 years) completed the pre-and post-intervention testing(FC: n = 13, HC: n = 12, CO(control):n = 10). The training attendance was 2.0 ± 0.4 and 1.9 ± 0.3 times per week in FC and HC, respectively. Mean heart rate(HR) was 83.8 ± 6.0 percent of maximal heart rate(%HR_(max)) and 84.5 ± 2.9 %HR_(max) in FC and HC, ***: The 3 months of street basketball training on an FC with 2 baskets increased maximal oxygen uptake(2.4 mL/min/kg(95% confidence interval(CI): 1.0—3.9)), time to exhaustion(47 s(95%CI: 26—67)), lean body mass(0.8 kg(95%CI: 0.1—1.5)), and bone mineral density(0.021 g/cm^2(95%CI: 0.011—0.031)), whereas mean arterial pressure(—5.6 mm Hg(95%CI: —7.5 to 3.7)), body fat percentage(—1.6%,(95%CI: —2.5 to —0.7)), heart rate(—18 bpm(95%CI: —24 to —12)), and blood lactate(median: —1.4 mmol/L(interquartile range: —1.5 to —0.6)) during submaximal running were lowered. The changes were less pronounced after the training period when playing on an HC with 1 basket, but increases in maximal oxygen uptake(1.6 mL/min/kg(95%CI: —0.1 to 3.3)), time to exhaustion(28 s(95%CI: 9—47)), lean body mass(1.3 kg(95%CI: 0.3—2.4)), and lower body fat percentage(—0.9%(95%CI: —1.9 to —0.1)) were observed in this ***: Three months of 3 v 3 street basketball training improved fitness and led to broad-spectrum improvements in variables related to overall health profile, with the most marked effects observed when playing on an FC with 2 baskets.

关键词：训练健康篮球侧面物质密度体质量 HC FC