http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : K. Nielsen (검색결과 30 건)
- 무료
- 기관 내 무료
- 유료
-
-Lipoic acid prevents cisplatin-induced acute kidney injury in rats
Bae, E. H.,Lee, J.,Ma, S. K.,Kim, I. J.,Frokiaer, J.,Nielsen, S.,Kim, S. Y.,Kim, S. W. Oxford University Press 2009 Nephrology, dialysis, transplantation Vol.24 No.9
<P>BACKGROUND: Cisplatin-induced nephropathy has been related to increased lipid peroxide formation and decreased activity of antioxidant enzymes in the kidney. The present study aimed to examine whether treatment with alpha-lipoic acid (alpha-LA) prevents the cisplatin-induced nephrotoxicity. METHODS: Two groups of rats were treated with cisplatin, one of which being cotreated with alpha-LA. The control group was treated with vehicle only. Four days later, the expression of aquaporins and sodium transporters was determined in the kidney by immunoblotting and immunohistochemistry. The arginine vasopressin-stimulated generation of cAMP was measured by radioimmunoassay. The expression of nitric oxide synthases (NOS) was determined by immunoblotting. The mRNA expression of endothelin-1 (ET-1) and tumour necrosis factor (TNF)-alpha was measured by real-time PCR. Apoptosis was examined by TUNEL staining. RESULTS: Following the treatment with cisplatin, urinary volume and fractional excretion of sodium increased. Accordingly, the expression of aquaporins 1-3, Na,K-ATPase, NHE3 and NKCC2 was decreased. The expression of adenylyl cyclase VI and vasopressin-stimulated cAMP generation was decreased. The expression of inducible NOS was increased, while that of endothelial NOS decreased. The ET-1 expression was increased. TUNEL-positive cells were increased, in association with an increased expression of TNF-alpha. alpha-LA treatment prevented dysregulation of these parameters and resumed the renal function. CONCLUSION: alpha-LA may prevent the cisplatin-induced nephrotoxicity, possibly through preserving the activities of NO and ET systems and inhibiting the development of apoptosis.</P>
-
-
On the nonlinear structural analysis of wind turbine blades using reduced degree-of-freedom models
K. Holm-Jørgensen,J.W. Stærdahl,S.R.K. Nielsen 국제구조공학회 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.28 No.1
Wind turbine blades are increasing in magnitude without a proportional increase of stiffness for which reason geometrical and inertial nonlinearities become increasingly important. Often these effects are analysed using a nonlinear truncated expansion in undamped fixed base mode shapes of a blade, modelling geometrical and inertial nonlinear couplings in the fundamental flap and edge direction. The purpose of this article is to examine the applicability of such a reduced-degree-of-freedom model in predicting the nonlinear response and stability of a blade by comparison to a full model based on a nonlinear co-rotating FE formulation. By use of the reduced-degree-of-freedom model it is shown that under strong resonance excitation of the fundamental flap or edge modes, significant energy is transferred to higher modes due to parametric or nonlinear coupling terms, which influence the response and stability conditions. It is demonstrated that the response predicted by such models in some cases becomes instable or chaotic. However, as a consequence of the energy flow the stability is increased and the tendency of chaotic vibrations is reduced as the number of modes are increased. The FE model representing the case of infinitely many included modes, is shown to predict stable and ordered response for all considered parameters. Further, the analysis shows that the reduced-degree-of-freedom model of relatively low order overestimates the response near resonance peaks, which is a consequence of the small number of included modes. The qualitative erratic response and stability prediction of the reduced order models take place at frequencies slightly above normal operation. However, for normal operation of the wind turbine without resonance excitation 4 modes in the reduced-degree-of-freedom model perform acceptable.
-
Simulation model for Francis and Reversible Pump Turbines
Nielsen, Torbjorn K. Korean Society for Fluid machinery 2015 International journal of fluid machinery and syste Vol.8 No.3
When simulating the dynamic behaviour of a hydro power plant, it is essential to have a good representation of the turbine behaviour. The pressure transients in the system occurs because the flow changes, which the turbine defines. The flow through the turbine is a function of the pressure, the speed of rotation and the wicket gate opening and is, most often described in a performance diagram or Hill diagram. In the Hill diagram, the efficiency is drawn like contour lines, hence the name. A turbines Hill diagram is obtained by performance tests on scaled model in a laboratory. However, system dynamic simulations have to be performed in the early stage of a project, before the turbine manufacturer has been chosen and the Hill diagram is known. Therefore one have to rely on diagrams for a turbine with similar speed number. The Hill diagram is drawn through measured points, so for using the diagram in a simulation program, one have to iterate in the diagram based on curve fitting of the measured points. This paper describes an alternative method. By means of the Euler turbine equation, it is possible to set up two differential equations which represents the turbine performance with good enough accuracy for the dynamic simulations. The only input is the turbine's main geometry, the runner blade in- and outlet angle and the guide vane angle at best efficiency point of operation (BEP). In the paper, simulated turbine characteristics for a high head Francis turbine, and for a reversible pump turbine are compared with laboratory measured characteristics.
-
A water treatment case study for quantifying model performance with multilevel fl ow modeling
Emil K. Nielsen,Mads V. Bram,Jerome Frutiger,Gürkan Sin,Morten Lind 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.4
Decision support systems are a key focus of research on developing control rooms to aid operators inmaking reliable decisions and reducing incidents caused by human errors. For this purpose, models ofcomplex systems can be developed to diagnose causes or consequences for specific alarms. Modelsapplied in safety systems of complex and safety-critical systems require rigorous and reliable modelbuilding and testing. Multilevel flow modeling is a qualitative and discrete method for diagnosing faultsand has previously only been validated by subjective and qualitative means. To ensure reliability duringoperation, this work aims to synthesize a procedure to measure model performance according todiagnostic requirements. A simple procedure is proposed for validating and evaluating the concept ofmultilevel flow modeling. For this purpose, expert statements, dynamic process simulations, and pilotplant experiments are used for validation of simple multilevel flow modeling models of a hydrocycloneunit for oil removal from produced water.
-
Simulation model for Francis and Reversible Pump Turbines
Torbjørn K. Nielsen 한국유체기계학회 2015 International journal of fluid machinery and syste Vol.8 No.3
When simulating the dynamic behaviour of a hydro power plant, it is essential to have a good representation of the turbine behaviour. The pressure transients in the system occurs because the flow changes, which the turbine defines. The flow through the turbine is a function of the pressure, the speed of rotation and the wicket gate opening and is, most often described in a performance diagram or Hill diagram. In the Hill diagram, the efficiency is drawn like contour lines, hence the name. A turbines Hill diagram is obtained by performance tests on scaled model in a laboratory. However, system dynamic simulations have to be performed in the early stage of a project, before the turbine manufacturer has been chosen and the Hill diagram is known. Therefore one have to rely on diagrams for a turbine with similar speed number. The Hill diagram is drawn through measured points, so for using the diagram in a simulation program, one have to iterate in the diagram based on curve fitting of the measured points. This paper describes an alternative method. By means of the Euler turbine equation, it is possible to set up two differential equations which represents the turbine performance with good enough accuracy for the dynamic simulations. The only input is the turbine’s main geometry, the runner blade in- and outlet angle and the guide vane angle at best efficiency point of operation (BEP). In the paper, simulated turbine characteristics for a high head Francis turbine, and for a reversible pump turbine are compared with laboratory measured characteristics.
-
On the nonlinear structural analysis of wind turbine blades using reduced degree-of-freedom models
Holm-Jorgensen, K.,Staerdahl, J.W.,Nielsen, S.R.K. Techno-Press 2008 Structural Engineering and Mechanics, An Int'l Jou Vol.28 No.1
Wind turbine blades are increasing in magnitude without a proportional increase of stiffness for which reason geometrical and inertial nonlinearities become increasingly important. Often these effects are analysed using a nonlinear truncated expansion in undamped fixed base mode shapes of a blade, modelling geometrical and inertial nonlinear couplings in the fundamental flap and edge direction. The purpose of this article is to examine the applicability of such a reduced-degree-of-freedom model in predicting the nonlinear response and stability of a blade by comparison to a full model based on a nonlinear co-rotating FE formulation. By use of the reduced-degree-of-freedom model it is shown that under strong resonance excitation of the fundamental flap or edge modes, significant energy is transferred to higher modes due to parametric or nonlinear coupling terms, which influence the response and stability conditions. It is demonstrated that the response predicted by such models in some cases becomes instable or chaotic. However, as a consequence of the energy flow the stability is increased and the tendency of chaotic vibrations is reduced as the number of modes are increased. The FE model representing the case of infinitely many included modes, is shown to predict stable and ordered response for all considered parameters. Further, the analysis shows that the reduced-degree-of-freedom model of relatively low order overestimates the response near resonance peaks, which is a consequence of the small number of included modes. The qualitative erratic response and stability prediction of the reduced order models take place at frequencies slightly above normal operation. However, for normal operation of the wind turbine without resonance excitation 4 modes in the reduced-degree-of-freedom model perform acceptable.
-
-
Rasmus K. Storm,Klaus Nielsen 글로벌지식마케팅경영학회 2023 Journal of Global Sport Management Vol.8 No.4
Research into the development and competitiveness of national elite sport systems has grown significantly in recent years. Most research concerns large or medium-sized nations whereas studies of elite sport systems in small nations are notably absent. This paper focuses on a (very) small nation and its efforts to become competitive in international elite sport. Using the nine pillars of the SPLISS framework, the study assesses the strengths and weaknesses of Greenland’s elite sport system. From a pure results perspective, Greenland performs below expectations. This is partly the result of its climatic and geographical conditions and low population density. The case study of elite sport in Greenland has intrinsic value in its analysis of a nation with extreme conditions in this respect. The case study is also used to suggest general conclusions regarding the capabilities and limitations of elite sport systems in small nations.
-
DBpia연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
