24 research outputs found
Temperature dependent resistivity in the low resistance region for diffusive transport in two-dimensions
No full textThe interpretation of the metal-insulator transition phenomena in disordered two-dimensional electron systems in terms of density-dependent scaling variables suggests the existence of a quantum critical point at some critical electron density. However a first principles scaling theory based on renormalization group (RG) methods predicts a strong temperature dependence of the dimensionless resistivity R(T), even at small R(T), that is not observed. The observed properties are in fact consistent with a weakly disordered Fermi liquid, and there are no indications of strong temperature dependence induced by scaling. While the RG expansion in a power series in R(T) has only been evaluated to lowest order, this should be sufficient to describe experiments in the region of very small R. A further apparent anomaly is a return from metal-like to insulating-like behavior for increasing density. We explain these fundamental discrepancies between the first principles theory and experiment. We find that the R<<1 data in the currently attainable temperature range are in a weak scaling regime described by the logarithmic approximation. We independently determine the density dependent prefactor of the logarithm using data for the spin susceptibility and effective mass. We find good agreement between theory and experiment for R(T) in the diffusive regime. We point out that there are corrections to the leading logarithm approximation that should be observable at still lower temperatures
Lateral-photoeffect position-sensitive detectors
No full textSummary in DutchElectrical Engineering, Mathematics and Computer ScieneElectrical Engineering, Mathematics and Computer Scienc
Aspects of robot vision and object verification
No full textElectrical Engineering, Mathematics and Computer Scienc
Applying data-assimilation and calibration in the field of urban drainage
No full textMathematical PhysicsApplied MathematicsElectrical Engineering, Mathematics and Computer Scienc
Success of early equipment management, autonomous maintenance and training & education in the start-up of a new production line: A case study at Heineken
No full textManufacturing organizations have to become more competitive. There are two important things a company can do: become more efficient in all operations and introduce new products. Total Productive Maintenance (TPM) is a production philosophy that contributes to more efficiency. The introduction of new products sometimes require new production lines, which have to be started up. In this research TPM and the startup of a new production line come together. This thesis tries to create more insight in what influences the success of the TPM elements Early Equipment Management (EEM), Autonomous Maintenance (AM) and Training and Education (T&E) in the startup of a new production line by investigating the three elements during a case study at the packaging department of Heineken Zoeterwoude. Success has a different definition looking at the three elements. EEM success is defined as equipment satisfaction and vertical startup. AM success is defined as a quick and successful implementation of AM step three in the new line. Finally T&E success is defined as what operators find important in a T&E program during a startup. This research searched for factors that influence these successes. To realize this, this research first broadly consolidated TPM literature which appeared not to be sufficient. Additional theory was needed. Therefore the three elements were thoroughly observed and studies at Heineken, to find similarities with other theories. This showed that looking at the success of EEM, theory on systems engineering, production startup (problems) and project and process management seemed applicable to add possible influential factors. AM at Heineken showed that a lot of general TPM implementation barriers appeared (apart from AM barriers). Therefore theory on general TPM implementation barriers seem appropriate to add possible influential factors to AM. T&E was a bit harder, because it was obvious that theory on learning seems applicable, but hard to investigate. Therefore the choice was made to look for factors that could improve learning and let operators elaborate on these. Theory on learning improvement was therefore used. To investigate all factors, for each elements different important responders were questioned and on top of that extensive observations were done by close participation in the startup. This research showed that for EEM, theory on systems engineering could be a important contributor to EEM success. Also theory on production startup (problems) has to be taken into account since factors form this theory could influence EEM success. The impact of project and process management was not really indicated in this research, but there contribution to EEM success is assumed, because factors from project and process management do influence other factors (that do influence EEM success). Secondly this research showed that apart from AM barriers, general TPM implementation barriers have a large impact on a successful implementation of AM in the startup of a new production line. Thirdly this research showed that theory on learning improvement is important to show what operators find important in a T&E program when starting up a new line. Finally this research showed that there are a lot of relation between influential factors looking at the three elements. Factors influencing each other suggests that some are higher in hierarchy as others. Looking at all the influential factors, their descriptions given by respondents and the relations between them, made it easy to set very tangible recommendations for Heineken, so that these elements can be more successfully managed in future startups.SEPAMEnergy & IndustryTechnology, Policy and Managemen
Wondheling door middel van angiogenese
No full textWondheling gebasseerd op drie diffusie vergelijkingen die de concentratie van groeifactor (MDGF), de concentratie zuurstof en de haarvaten dichtheid aan elkaar koppelen.Technische wiskundeApplied mathematicsElectrical Engineering, Mathematics and Computer Scienc
Development of Metal/Metal Hip Resurfacing
No full text This author's development of metal/metal hip resurfacing began in 1989, with the first patient implantation in February 1991. In the first three years a pilot study identified optimum fixation as hydroxyapatite coated uncemented cups and cemented femoral components. From March 1994 hybrid fixed components have been used. These implants have generally been satisfactory with respect to fixation but high wear of the bearing, metallosis and osteolysis have been seen with some components inserted during 1996, a period during which the metal microstructure was altered by the heat processes, hot isostatic pressing and solution heat treatment. The Birmingham Hip Resurfacing was developed taking account of experience with earlier resurfacing designs. This implant employs hybrid fixation with a porous ingrowth acetabular component and has an as-cast metal microstructure having had no post casting heat treatments. During the past 4 years the author has performed over 1,000 Birmingham Hip Resurfacingís with a total failure rate of less than 1.0%. </jats:p
Acoustic Detection Of The Magnetocaloric Effect: Application To Gd And Gd5.09 Ge2.03 Si1.88
No full textIn this paper we present a simple method for the determination of the total magnetocaloric effect based on the acoustic detection of the adiabatic temperature rise caused by the application of an ac magnetic field of small amplitude. The continuous scanning of a superimposed dc magnetic field allows, by numerical integration, the determination of large temperature variations caused by magnetic field steps from zero to tens of kOe. Absolute values of temperature rise are easily acquired after the calibration of the microphone signal using an appropriate reference sample. Once the calibration is done, no further information about the sample's thermal properties is necessary since the measured signal is directly proportional to the temperature variation. Measurements were made in Gd and Gd5.09 Ge2.03 Si1.88 samples in the temperature range from 240 to 320 K. The technique shows to be suitable for the investigation of materials undergoing both purely magnetic phase transitions, as in the case of Gd, and magnetic-crystallographic first-order ones, as observed for Gd5.09 Ge2.03 Si1.88. Besides the ability to determine the temperature variation due to a large magnetic field step through the continuous scanning of the magnetic field, the technique is also very suitable for measuring the magnetocaloric effect under very small magnetic field steps since it has sensitivity below millikelvin. Moreover, it is able to detect temperature variations in very small amount of sample, leading to its potential application in magnetocaloric thin films. © 2009 The American Physical Society.8013Foldeaki, M., Schnelle, W., Gmelin, E., Benard, P., Koszegi, B., Giguere, A., Chahine, R., Bose, T.K., (1997) J. Appl. Phys., 82, p. 309. , 10.1063/1.365813Pecharsky, V.K., Gschneidner, Jr.K.A., (1999) J. Appl. Phys., 86, p. 565. , 10.1063/1.370767Gopal, B.R., Chahine, R., Bose, T.K., (1997) Rev. Sci. Instrum., 68, p. 1818. , 10.1063/1.1147999Pecharsky, V.K., Gschneidner, Jr.K.A., (1999) J. Magn. Magn. Mater., 200, p. 44. , 10.1016/S0304-8853(99)00397-2Pecharsky, V.K., Gschneidner, Jr.K.A., (1997) Phys. Rev. Lett., 78, p. 4494. , 10.1103/PhysRevLett.78.4494Otowski, W., Glorieux, C., Hofman, R., Thoen, J., (1993) Thermochim. Acta, 218, p. 123. , 10.1016/0040-6031(93)80416-8Gopal, B.R., Chahine, R., Földeàki, M., Bose, T.K., (1995) Rev. Sci. Instrum., 66, p. 232. , 10.1063/1.1145264Rosencwaig, A., Gersho, A., (1976) J. Appl. Phys., 47, p. 64. , 10.1063/1.322296Pecharsky, V.K., Gschneidner, Jr.K.A., (2001) Adv. Mater., 13, p. 683. , 10.1002/1521-4095(200105)13:93.0.CO;2-OVon Ranke, P.J., De Oliveira, N.A., Gama, S., (2004) J. Magn. Magn. Mater., 277, p. 78. , 10.1016/j.jmmm.2003.10.013Carvalho, A.M.G., Alves, C.S., Campos, A., Coelho, A.A., Gama, S., Gandra, F.C.G., Von Ranke, P.J., Oliveira, N.A., (2005) J. Appl. Phys., 97, pp. 10M320. , 10.1063/1.1860932Pecharsky, A.O., Gschneidner, Jr.K.A., Pecharsky, V.K., (2003) J. Magn. Magn. Mater., 267, p. 60. , 10.1016/S0304-8853(03)00305-6Gama, S., Alves, C.S., Coelho, A.A., Ribeiro, C.A., Persiano, A.I.C., Silva, D., (2004) J. Magn. Magn. Mater., 272-276, p. 848. , 10.1016/j.jmmm.2003.12.1260Pires, M.J.M., Carvalho, A.M.G., Gama, S., Da Silva, E.C., Coelho, A.A., Mansanares, A.M., (2005) Phys. Rev. B, 72, p. 224435. , 10.1103/PhysRevB.72.224435Glorieux, C., Thoen, J., Bednarz, G., White, M.A., Geldart, D.J.W., (1995) Phys. Rev. B, 52, p. 12770. , 10.1103/PhysRevB.52.12770Bednarz, G., Geldart, D.J.W., White, M.A., (1993) Phys. Rev. B, 47, p. 14247. , 10.1103/PhysRevB.47.14247Yu. Dan'Kov, S., Tishin, A.M., Pecharsky, V.K., Gschneidner, Jr.K.A., (1998) Phys. Rev. B, 57, p. 3478. , 10.1103/PhysRevB.57.3478Glorieux, C., Caerels, J., Thoen, J., (1996) J. Appl. Phys., 80, p. 3412. , 10.1063/1.363208Pecharsky, V.K., Gschneidner, Jr.K.A., (1999) J. Appl. Phys., 86, p. 6315. , 10.1063/1.371734Giguere, A., Foldeaki, M., Ravi Gopal, B., Chahine, R., Bose, T.K., Frydman, A., Barclay, J.A., (1999) Phys. Rev. Lett., 83, p. 2262. , 10.1103/PhysRevLett.83.2262Yue, M., Zhang, J., Zeng, H., Chen, H., Liu, X.B., (2006) J. Appl. Phys., 99, pp. 08Q104. , 10.1063/1.2158971Tocado, L., Palacios, E., Burriel, R., (2006) J. Therm Anal. Calorim., 84, p. 213. , 10.1007/s10973-005-7180-zGschneidner, Jr.K.A., Pecharsky, V.K., Brück, E., Duijn, H.G.M., Levin, E.M., (2000) Phys. Rev. Lett., 85, p. 4190. , 10.1103/PhysRevLett.85.419
