A simplified method to account for the non linearity of aerodynamic coefficients in the analysis of wind-loaded bridges

in Proceedings of the 7th National Congres on Theoretical and Applied Mechanics (2006)

Based on a non linear quasi-steady wind model, this paper presents the statistical characteristics of the wind loading. These statistical characteristics are computed in an analysical way and validated ... [more ▼]

Based on a non linear quasi-steady wind model, this paper presents the statistical characteristics of the wind loading. These statistical characteristics are computed in an analysical way and validated thanks to a Monte Carlo simulation.After this validation, a parametric study allows giving some general observations concerning the non Gaussianity of the loading. Statistical moments up to the fourth order are computed in an analytical way. The subsequent relations are expressed as a function of the slope and curvature of the aerodynamic coefficients. They are a usefull tool for the assessment of the non Gaussianity of the wind loading on any bridge deck. This is illustrated for three famous European bridges. [less ▲]

A simplified one-pot synthesis of 9-[(3-[18F]fluoro-1-hydroxy-2-propoxy)methyl]guanine([18F]FHPG) and 9-(4-[18F]fluoro-3-hydroxymethylbutyl)guanine ([18F]FHBG) for gene therapy.

in Nuclear Medicine & Biology (2001), 28(7), 875-83

9-[(3-[18F]Fluoro-1-hydroxy-2-propoxy)methyl]guanine ([18F]FHPG, 2) has been synthesized by nucleophilic substitution of N(2)-(p-anisyldiphenylmethyl)-9-[[1-(p-anisyldiphenylmethoxy)-3-toluenesulfonylox y ... [more ▼]

9-[(3-[18F]Fluoro-1-hydroxy-2-propoxy)methyl]guanine ([18F]FHPG, 2) has been synthesized by nucleophilic substitution of N(2)-(p-anisyldiphenylmethyl)-9-[[1-(p-anisyldiphenylmethoxy)-3-toluenesulfonylox y-2-propoxy]methyl]guanine (1) with potassium [18F]fluoride/Kryptofix 2.2.2 followed by deprotection with 1 N HCl and purification with different methods in variable yields. When both the nucleophilic substitution and deprotection were carried out at 90 degrees C and the product was purified by HPLC (method A), the yield of compound 2 was 5-10% and the synthesis time was 90 min from EOB. However, if both the nucleophilic substitution and deprotection were carried out at 120 degrees C and the product was purified by HPLC, the yield of compound 2 decreased to 2%. When compound 2 was synthesized at 90 degrees C and purified by Silica Sep-Pak (method B), the yield increased to 10-15% and the synthesis time was 60 min from EOB. Similarly, 9-(4-[18F]fluoro-3-hydroxymethylbutyl)guanine ([18F]FHBG, 4) was synthesized with method A and method B in 9% and 10-15% yield, respectively, in a synthesis time of 90 and 60 min, respectively, from EOB. Compound 2 was relatively unstable in acidic medium at 120 degrees C while compound 4 was stable under the same condition. Both compound 2 and compound 4 had low lipid/water partition coefficient (0.126 +/- 0.022, n=5 and 0.165 +/- 0.023, n=5, respectively). Although it contains non-radioactive ganciclovir ( approximately 5-30 microg) as a chemical by-product, compound 2 synthesized by method B has a similar uptake in 9L glioma cells as that synthesized by method A, and is a potential tracer for imaging herpes simplex virus thymidine kinase gene expression in tumors using PET. Similarly, compound 4 synthesized by method B contains approximately 10-25 microg of penciclovir as a chemical by-product. Thus, the simplified one pot synthesis (method B) is a useful method for synthesizing both compound 2 and compound 4 in good yield for routine clinical use, and the method is readily amenable for automation. [less ▲]

A Simplified Rotational Spring Model for Mitral Valve Dynamics

in Proceedings of control 2010 (2010, September 07)

A simple non-linear rotational spring model has been implemented to model the motion of mitral valve, located between the left atrium and ventricle. A measured pressure difference curve was used as the ... [more ▼]

A simple non-linear rotational spring model has been implemented to model the motion of mitral valve, located between the left atrium and ventricle. A measured pressure difference curve was used as the input into the model, which represents an applied torque to the valve chords. Various damping and hysteresis states were investigated to find a model that best matches reported animal data of chord movement during a heartbeat. The study is limited by the use of one dataset from the literature, however results clearly highlight some physiological issues such as the damping and chord stiffness changing within one cardiac cycle. Very good correlation was achieved between modeled and experimental valve angle, indicating good promise for future simulation of cardiac dysfunction, such as mitral regurgitation or stenosis. [less ▲]

Simplified time-domain simulation of detailed long-term dynamic models

in Proceedings of the 2009 IEEE PES General Meeting (2009, July)

Time-domain simulation of power system long-term dynamics involves the solution of large sparse systems of nonlinear stiff differential-algebraic equations. Simulation tools have traditionally focused on ... [more ▼]

Time-domain simulation of power system long-term dynamics involves the solution of large sparse systems of nonlinear stiff differential-algebraic equations. Simulation tools have traditionally focused on the accuracy of the solution and, in spite of many algorithmic improvements, time simulations still require a significant computational effort. In some applications, however, it is sufficient to have an approximate system response of the detailed model. The paper revisits the merits of the Backward Euler method and proposes a strategy to control its step size, with the objective of filtering out fast stable oscillations and focusing on the aperiodic behaviour of the system. The proposed method is compared to detailed simulation as well as to the quasi-steadystate approximation. Illustrative examples are given on a small but representative system, subject to long-term voltage instability. [less ▲]

Simplifying strong electronic correlations in uranium: Localized uranium heavy-fermion UM(2)Zn(20) (M = Co, Rh) compounds

in Physical Review. B : Condensed Matter (2008), 78(11),

The physical properties including magnetic susceptibility, magnetization, specific heat, and dynamic susceptibility chi ''(E) are reported for single crystals of the cubic UM(2)Zn(20) (M = Co, Rh ... [more ▼]

The physical properties including magnetic susceptibility, magnetization, specific heat, and dynamic susceptibility chi ''(E) are reported for single crystals of the cubic UM(2)Zn(20) (M = Co, Rh) materials. Maxima in the thermodynamic data at T(max) similar to 10 K for both compounds and a broad peak in chi ''(E) at 5 K in UCo(2)Zn(20) of width Gamma=5 meV indicate a heavy-fermion state characterized by a Kondo temperature T(K) similar to 20-30 K arising from weak hybridization of f- and conduction-electron states. Anderson impurity model fits to the data in the Kondo limit including crystalline electric-field effects corroborate an ionic-like uranium electronic configuration in UM(2)Zn(20). [less ▲]

Simulated And Measured Coefficients Of Variation For The Spray Distribution Under A Static Spray Boom

in Journal of Agricultural Engineering Research (2000), 76(4), 381-388

The spray pattern characteristics of a number of different series of flat fan nozzles were investigated in two ways. The first method was to measure the distribution by means of a classic patternator with ... [more ▼]

The spray pattern characteristics of a number of different series of flat fan nozzles were investigated in two ways. The first method was to measure the distribution by means of a classic patternator with collecting cylinders. The second method consisted of numerical simulation of the distribution, by combining the real distributions of a number of nozzles. The real distribution was measured on a classic patternator for each nozzle separately. The numerical simulation is computerized and automated. This system allows both time and labour gains, and permits multiple trials with the same series of nozzles. Numerical simulation results are compared with spray distributions obtained on the patternator. The sprayed volumes of liquid were found to be significantly different from the simulated ones (level of significance 95%). However, the coefficient of variation characterizing the homogeneity of the spread volumes can be calculated using simulated volumes. This can be done once an empirical linear relation is established between the coefficients of variation obtained from simulated volumes and the ones obtained from measured volumes. [less ▲]

The simulated detection of low-mass companions with GENIE

in Traub, Wesley; Monnier, John; Schöller, Markus (Eds.) New Frontiers in Stellar Interferometry (2004, October 01)

The prime objective of GENIE (Ground-based European Nulling Interferometry Experiment) is to obtain experience with the design, construction and operation of an IR nulling interferometer, as a preparation ... [more ▼]

The prime objective of GENIE (Ground-based European Nulling Interferometry Experiment) is to obtain experience with the design, construction and operation of an IR nulling interferometer, as a preparation for the DARWIN / TPF mission. In this context, the detection of a planet orbiting another star would provide an excellent demonstration of nulling interferometry. Doing this through the atmosphere, however, is a formidable task. In this paper we assess the prospects of detecting with nulling interferometry on ESO's VLTI, low-mass companions in orbit around their parent stars. With the GENIE science simulator (GENIEsim) we can model realistic detection scenarios for the GENIE instrument operating in the VLTI environment, and derive detailed requirements on control-loop performance, IR background subtraction and the accuracy of the photometry calibration. We analyse the technical feasibility of several scenarios for the detection of low-mass companions in the L'-band. [less ▲]

Simulated growth front of 123-(RE)BCO near 211 particles

in Physica C: Superconductivity (1994), 235(Part 1), 427-428

The microstructural features observed on some DyBa2Cu3O7-x, samples show that kinetic considerations are as important as thermodynamic ones. In order to compute and characterize the kinetic growth front ... [more ▼]

The microstructural features observed on some DyBa2Cu3O7-x, samples show that kinetic considerations are as important as thermodynamic ones. In order to compute and characterize the kinetic growth front of 123-(RE)BCO compounds, we have introduced an anisotropic growth direction into a simple two-dimensional growth model: the Eden model defined on a square lattice. The presence of 211 particles has been also considered. The simulated patterns in the ab and ac planes agree with observations and contribute to a more comprehensive model of the kinetic of the growth front near 211 particles. [less ▲]

Le simulateur comme outil de formation et de recherche

Conference (2002)

Simulating the growth of supra-glacial lakes at the western margin of the Greenland ice sheet

in Cryosphere (The) (2012), 6

We present a new method of modelling the growth of supraglacial lakes at the western margin of the Greenland ice sheet, based on routing runoff estimated by a regional climate model across a digital ... [more ▼]

We present a new method of modelling the growth of supraglacial lakes at the western margin of the Greenland ice sheet, based on routing runoff estimated by a regional climate model across a digital elevation model (DEM) of the ice sheet surface. Using data acquired during the 2003 melt season, we demonstrate that the model is 19 times more likely to correctly predict the presence (or absence) of lakes than it is to make incorrect predictions, within an elevation range of 1100 to 1700 metres above sea level (m a.s.l.), when compared with MODIS satellite imagery. Of the 66% of observed lake locations which the model correctly reproduces, the simulated lake onset day is found to be correlated with that observed with a Pearson correlation coefficient of 0.76. Our model accurately simulates maximum cumulative lake area with only a 1.5% overestimate. However, because our model does not simulate processes leading to lake stagnation or decay, such as refreezing or drainage, at present we do not simulate absolute daily lake area. We find that the maximum potential lake-covered ice sheet area is limited by topography to 6.4%. We estimate that this corresponds to a volume of 1.49 km3, 12% of the runoff produced in 2003. This can be taken as an upper bound given uncertainty in the DEM. This study has proved a good first step towards capturing the variability of supraglacial lake evolution with a numerical model. These initial results are promising and suggest that the model is a useful tool for use in analysing the behaviour of supraglacial lakes on the Greenland ice sheet in the present day and potentially beyond. [less ▲]