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Influence of rotating wakes on separation in turbine exhaust diffusers

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Journal of Thermal Science 2008年第1期17卷 42-49页

作者： olaf Sieker Joerg R.Seume Department of Turbomachinery and Fluid Dynamics Leibniz University HannoverAppelstr.9DE-30167 HannoverGermany Dipl.-Ing. Department of Turbomachinery and Fluid Dynamics Leibniz University HannoverAppelstr.9DE-30167 HannoverGermany

Highly efficient turbine exhaust diffuser cannot be designed without taking into account the unsteady interactions with the last rotating row of the turbine. Former investigations described in the literature show a very high potential compared to that of other parts of turbomachines for improving the diffuser. A scale model of a typical gas turbine exhaust diffuser is investigated experimentally. To investigate the influence of rotating wakes, measurements without a spoke wheel as well as measurements with a variable-speed rotating cylindrical spoke wheel with 2 mm- or 10 mm-spokes simulating turbine rotor wakes were made. Miniaturized 3-hole pneumatic probes as well as a 2D-Laser-Doppler-Velocimeter （LDV） were used to investigate velocity profiles. 122 static pressure tapings were used to measure several axial and circumferential static pressure distributions. Without a spoke-wheel the annular diffuser separates at the shroud for all swirl configurations. For the measurements with the 2 mm spoke wheel, the separating diffuser was unstable while keeping the test rig operating parameters constant. For a non-rotating 10 mm spoke wheel and at rotational speeds less than 1,000 rpm, the annular diffuser separated at the shroud. Increasing the rotational speed of the 10mm spoke wheel, flow did not separate at the shroud and much higher pressure recovery than without spoke wheel has achieved.

关键词： turbine exhaust diffuser rotating wakes separation LDV

Impacts of prenatal nutrition on animal production and performance： a focus on growth and metabolic and endocrine function in sheep

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Journal of Animal Science and Biotechnology 2018年第1期9卷 10-23页

作者： Prabhat Khanal Mette olaf Nielsen Department of Veterinary and Animal Sciences Faculty of Health and Medical SciencesUniversity of Copenhagen Gronnegardsvey 31st floorDK-1870 Frederiksberg CDenmark Department of Nutrition Faculty of MedicineTransgenic Animal and Lipid StorageNorwegian Transgenic Centre(NTS)University of OsloOsloNotway

The concept of foetal programming（FP） originated from human epidemiological studies, where foetal life nutrition was linked to health and disease status later in life. Since the proposal of this phenomenon, it has been evaluated in various animal models to gain further insights into the mechanisms underlying the foetal origins of health and disease in humans. In FP research, the sheep has been quite extensively used as a model for humans. In this paper we will review findings mainly from our Copenhagen sheep model, on the implications of late gestation malnutrition for growth, development, and metabolic and endocrine functions later in life, and discuss how these implications may depend on the diet fed to the animal in early postnatal life. Our results have indicated that negative implications of foetal malnutrition, both as a result of overnutrition and, particularly, late gestation undernutrition, can impair a wide range of endocrine functions regulating growth and presumably also reproductive traits. These implications are not readily observable early in postnatal life, but are increasingly manifested as the animal approaches adulthood. No intervention or cure is known that can reverse this programming in postnatal life. Our findings suggest that close to normal growth and slaughter results can be obtained at least until puberty in animals which have undergone adverse programming in foetal life, but manifestation of programming effects becomes increasingly evident in adult *** to the risk of transfer of the adverse programming effects to future generations, it is therefore recommended that animals that are suspected to have undergone adverse FP are not used for reproduction. Unfortunately, no reliable biomarkers have as yet been identified that allow accurate identification of adversely programmed offspring at birth,except for very low or high birth weights, and, in pigs, characteristic changes in head shape（dolphin head）. Future efforts should be therefo

关键词： Adipose tissue Endocrine function Foetal programming Metabolic function Sheep

Effect of Different Calcination Temperatures and Post Annealing on the Properties of Acetic Acid Based Sol-Gel (Na_(0.5)K_(0.5))NbO_3(NKN) Thin Films

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Journal of Materials Science & Technology 2013年第2期29卷 142-148页

作者： Sebastian Wiegand Stefan Flege olaf Baake Wolfgang Ensinger Materials Analysis Group Department of Materials and Geosciences Technische Universitt Darmstadt Petersenstrasse 23 64287 Darmstadt Germany

（Na0.5K0.5）NbO3 （NKN） lead free thin films were synthesized by means of an acetic acid based sol-gel process on Pt/Ti/SiO2/Si substrates. Na-acetate, K-acetate and Nb-pentaethoxide were used as metal precursors and acetic acid as the solvent. The effect of different calcination temperatures on the properties of the NKN films was investigated by X-ray diffraction, scanning electron microscopy, leakage current and hysteresis measurements. Low calcination temperatures led to low currents at high electric fields whereas high calcination temperatures led to low currents at low electric fields. Based on these findings calcination at low temperature was combined with a post annealing treatment. Low leakage currents of 4×10^-4 A/cm2 at 150 kV/cm and 2Pr and 2Ec values of 28 μC/cm2 and 150 kV/cm, respectively, could be obtained. All films were single phase NKN with random crystal orientations and no crack or pore formation was visible on the surface.

关键词： Sol-gel process (Na0.5K0.5)NbO3 Thin film Perovskite Lead-free Piezo material

Synthesis and Characterization of(Na_(0.5)K_(0.5))NbO_3(NKN) Thin Films Formed by a Diol-based Sol-gel Process

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Journal of Materials Science & Technology 2012年第6期28卷 500-505页

作者： Sebastian Wiegand Stefan Flege olaf Baake Wolfgang Ensinger Technische Universitt Darmstadt Department of Materials and GeosciencesMaterials Analysis GroupPetersenstrasse 2364287 DarmstadtGermany

Lead-free （***0.5）Nb03 （NKN） thin films were fabricated by spin coating on Pt/Ti/SiO2/Si substrates by a diol-based sol-gel process. Na-acetate, K-acetate, Nb-pentaethoxide and 1,3 propanediol were used to prepare the NKN precursor solution. Thermal analysis showed two characteristic temperatures of 360 and 600℃. Based on these temperatures, a heat treatment program with pyrolysis at 360℃ and calcination at 600℃ after every layer was used. To avoid inhomogeneities and secondary phases, an excess of sodium and potassium was necessary. To evaluate the proper excess amount of sodium and potassium secondary ion mass spectrometry （SIMS） lateral element maps and X-ray diffraction （XRD） patterns were recorded. An excess amount of 20% led to homogeneous distribution of the elements and to single phase perovskite NKN films with random crystal orientation. Scanning electron microscopy （SEMI images showed a pore free surface with 100 nm grains. The leakage current measurements showed a current of lx10-3 A/cm2 at 150 kV/cm.

关键词： Sol-gel process (Nao.sK0.5)NbO3 Thin film Perovskite Lead-free Piezo material

Optical coatings:trends and challenges

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光学精密工程 2005年第4期13卷 389-396页

作者： Norbert Kaiser Torsten Feigl olaf Stenzel Ulrike Schulz Fraunhofer Institut für Angewandte Optik und Feinmechanik Albert-Einstein-Str. 7D-07745 Jena GermanyFraunhofer Institut für Angewandte Optik und Feinmechanik Albert-Einstein-Str. 7D-07745 Jena GermanyFraunhofer Institut für Angewandte Optik und Feinmechanik Albert-Einstein-Str. 7D-07745 Jena GermanyFraunhofer Institut für Angewandte Optik und Feinmechanik Albert-Einstein-Str. 7D-07745 Jena Germany

New applications in optoelectronics, photonics, telecommunication, displays, optical data processing, biomedicine, sensors, energy control, automobile, aerospace, and architecture stimulation are important developments in physics and technology of optical coatings. This paper will focus on the latest advances in the areas of new optical film systems and devices, new optical coating materials and film fabrication techniques, process control and monitoring, and different advanced applications. Particularly, focus is on optical films that combine optical design with microstructural features tailored on the nanometer and micrometer scales. Evaluation of film stability and integrity in harsh industrial environments and their compatibility with organic polymers are important as well.

关键词：光学涂覆技术光电子技术光学仪器光学材料

Fatalities caused by novel opioids:a review

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Forensic Sciences Research 2019年第2期4卷 95-110页

作者： olaf H.Drummer Department of Forensic Medicine School of Public Health and Preventive MedicineFaculty of MedicineNursing and Health SciencesMonash UniversitySouthbankVictoriaAustralia

Drugs related to morphine represent not only large range of important therapeutic applications for the relief of moderate to severe pain but also give rise to a relatively large series of novel opioids that mimic the action of this naturally occurring *** of these are based on fentanyl structures that are much more potent,and dangerous,than fentanyl *** publication reviews reports of fatalities attributed to 15 novel opioids with the view to assessing mortality associated with their misuse as well as reviewing published analytical procedures that would be able to detect these and other novel *** drugs include reports of deaths to acetylfentanyl,acrylfentanyl,butr(yl)fentanyl,carfentanil,2-and 4-fluorofentanyls,4-fluorobutyrfentanyl,4-fluoroisobutyrfentanyl,furanylfentanyl,a-and 3-methylfentanyls,4-methoxyfentanyl,ocfentanil,as well as AH-7921,U-47700 and *** of these cases reporting a drug-caused death involved other drugs in addition to the *** obvious minimum fatal concentration was discerned for any of the opioids for which details were provided,however,the more potent members required detection limits well under 1 ng/mL and often even well below 0.1 ng/mL requiring use of the most sensitive mass spectral detection procedures,particularly when screening specimens using a non-targeted *** other novel opioids have been reported in admissions to hospitals include 4-chloroisobutryfentanyl,cyclopentylfentanyl and tetrahydrofuranfentanyl,all of which are likely to have the potential to cause *** is also likely that other analogues will appear with time.

关键词： Forensic science forensic toxicology opioids poisoning illicit drugs novel psychoactive drugs fentanyl derivatives mass spectrometry

Numerical Investigation of the Temperature and Flow Fields in a Solar Chimney Power Plant

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Fluid Dynamics & Materials Processing 2023年第4期19卷 1055-1066页

作者： Roudouane Laouar olaf Wünsch Laboratory of Environment Larbi Tebessi UniversityTebessaAlgeria Department of Fluid Dynamics University of KasselKasselGermany

In this work,a parametric two-dimensional computational fluid dynamics(CFD)analysis of a solar chimney power plant(a prototype located in Manzanares,Spain)is presented to illustrate the effects of the solar radiation mode in the collector on the plant *** simulations rely on a mathematical model that includes solar radiation within the collector;energy storage;air flow and heat transfer,and a *** is based on the Navier-Stokes equation for turbulent flow formulated according to the standard k-ε***,the Boussinesq approach is used to account for the fluid density *** solar radiation modes in the collector are compared and *** obtained results are also compared with available experimental *** is shown that the radiation model is essential to avoid overestimation of the energy absorbed by the plant and that results based on a two-dimensional model can resemble closely those produced by three-dimensional models.

关键词： Solar radiation model two-dimensional axisymmetric model Boussinesq model greenhouse effect

Robowler:Design and development of a cricket bowling machine ensuring ball seam position

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Journal of Central South University 2014年第11期21卷 4142-4149页

作者： RAZA Ali DIEGEL olaf ARIF Khalid Mahmood Mechatronics and Control Engineering University of Engineering & TechnologyLahore 54890 Pakistan School of Engineering and Advanced Technology Massey UniversityAuckland 0632 New Zealand

The art of cricket bowling is complex and arduous owing to the run-up and ball release time energy requirement to achieve speed and variations. Therefore, human bowlers cannot bowl for extended periods and numerous mechanical bowling machines have been built to help batsmen improve their skills during practice sessions. However, most of these existing machines are designed for spherical balls ignoring the distinguishing physical feature of a cricket ball: the raised equatorial seam, which makes it less of a sphere. The bowlers are known to often benefit from this seam in their pursuit to taking the batsmen's wicket by imparting swing, spin and bounce variations along-with other bowling variables. This lack of the seam consideration creates a void between human and mechanical bowling. In this work, we present design and development of an automatic bowling machine termed as ROBOWLER to make mechanical bowling more realistic. This machine ensures ball seam position as well as fulfills other constraints. Ball pitching and seam position accuracy results underscore the suitability of this design to enhance the capabilities of mechanical bowling.

关键词： robowler bowling machine cricket bowling ball seam bowling variables

Visualizing perceived spatial data quality of 3D objects within virtual globes

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International Journal of Digital Earth 2014年第10期7卷 771-788页

作者： Krista Jones Rodolphe Devillers Yvan Bedard olaf Schroth Department of Geography Memorial University of NewfoundlandSt.John’sCanada Departement des sciences geomatiques Universite LavalQuebecCanada Department of Landscape The University of SheffieldSheffieldUK

Virtual globes(VGs)allow Internet users to view geographic data of heterogeneous quality created by other *** article presents a new approach for collecting and visualizing information about the perceived quality of 3D data in *** aims atimproving users’awareness of the qualityof 3D *** of relying onthe existing metadata or on formal accuracy assessments that are often impossible in practice,we propose a crowd-sourced quality recommender system based on the five-star visualization method successful in other types of Web *** alternative five-star visualizations were implemented in a Google Earth-based prototype and tested through a formal user *** tests helped identifying the most effective method for a 3D *** indicate that while most websites use a visualization approach that shows a‘number of stars’,this method was the least preferred by ***,participants ranked the‘number within a star’method highest as it allowed reducing the visual clutter in urban settings,suggesting that 3D environments such as VGs require different *** that expert and non-expert users in geographic data share similar preferences for the most and least preferred visualization methods.

关键词： virtual globes spatial data quality uncertainty quality recommender system five-star 3D objects