Experimental ratchet effect in superconducting films with periodic arrays of asymmetric potentials

A vortex lattice ratchet effect has been investigated in Nb films grown on arrays of nanometric Ni triangles, which induce periodic asymmetric pinning potentials. The vortex lattice motion yields a net dc-voltage when an ac driving current is applied to the sample and the vortex lattice moves through the field of asymmetric potentials. This ratchet effect is studied taking into account the array geometry, the temperature, the number of vortices per unit cell of the array and the applied ac currents.Comment: 15 pages, figures include

A new cluster-type statistical model for the prediction of deformation textures

An attempt was done to improve the quality of deformation texture predictions by statistical models through the introduction of "clusters" of N grains thus defining a third, intermediate length scale. The interaction between each cluster and the macroscopic length scale is of the Taylor type, whereas inside each cluster a VPSC scheme is used. Predictions of cold rolling deformation textures were quantitatively compared with experimental results for a steel alloy. The results are encouraging

Flux pinning properties of superconductors with an array of blind holes

We performed ac-susceptibility measurements to explore the vortex dynamics and the flux pinning properties of superconducting Pb films with an array of micro-holes (antidots) and non-fully perforated holes (blind holes). A lower ac-shielding together with a smaller extension of the linear regime for the lattice of blind holes indicates that these centers provide a weaker pinning potential than antidots. Moreover, we found that the maximum number of flux quanta trapped by a pinning site, i.e. the saturation number ns, is lower for the blind hole array.Comment: 6 figures, 6 page

Forming limit predictions for single-point incremental sheet metal forming

peer reviewedA characteristic of incremental sheet metal forming is that much higher deformations can be achieved than conventional forming limits. In this paper it is investigated to which extent the highly non-monotonic strain paths during such a process may be responsible for this high formability. A Marciniak-Kuczynski (MK) model is used to predict the onset of necking of a sheet subjected to the strain paths obtained by finite-element simulations. The predicted forming limits are considerably higher than for monotonic loading, but still lower than the experimental ones. This discrepancy is attributed to the strain gradient over the sheet thickness, which is not taken into account in the currently used MK model

Surface Enhancement of Superconductivity in Tin

The possibility of surface enhancement of superconductivity is examined experimentally. It is shown that single crystal tin samples with cold-worked surfaces represent a superconductor with a surface-enhanced order parameter (or negative surface extrapolation length b), whose magnitude can be controlled.Comment: 8 pages, 4 figure

Anisotropic vortex pinning in superconductors with a square array of rectangular submicron holes

We investigate vortex pinning in thin superconducting films with a square array of rectangular submicron holes ("antidots"). Two types of antidots are considered: antidots fully perforating the superconducting film, and "blind antidots", holes that perforate the film only up to a certain depth. In both systems, we observe a distinct anisotropy in the pinning properties, reflected in the critical current Ic, depending on the direction of the applied electrical current: parallel to the long side of the antidots or perpendicular to it. Although the mechanism responsible for the effect is very different in the two systems, they both show a higher critical current and a sharper IV-transition when the current is applied along the long side of the rectangular antidots

Thin film growth of semiconducting Mg2Si by codeposition

Includes bibliographical references (page 1088).Ultrahigh vacuum evaporation of magnesium onto a hot silicon substrate (⩾200 °C), with the intention of forming a Mg2Si thin film by reaction, does not result in any accumulation of magnesium or its silicide. On the other hand, codeposition of magnesium with silicon at 200 °C, using a magnesium-rich flux ratio, gives a stoichiometric Mg2Si film which can be grown several hundreds of nm thick. The number of magnesium atoms which condense is equal to twice the number of silicon atoms which were deposited; all the silicon condenses while the excess magnesium in the flux desorbs. The Mg2Si layers thus obtained are polycrystalline with a (111) texture. From the surface roughness analysis, a self-affine growth mode with a roughness exponent equal to 1 is deduced

Effect of FEM choices in the modelling of incremental forming of aluminium sheets

peer reviewedThis paper investigates the process of single point incremental forming of an aluminium cone with a 50-degree wall angle. Finite element (FE) models are established to simulate the process. Different FE packages have been used. Various aspects associated with the numerical choices as well as the material and process parameters have been studied. The final geometry and the reaction forces are presented as the results of the simulations. Comparison between the simulation results and the experimental data is also made

INITIAL SCREENING FOR BEDWETTING: THE USE OF QUESTIONNAIRES AND VOIDING DIARIES First results from a National Belgian study

Title Initial screening for bedwetting: the use of questionnaires and voiding diaries. First results from a National Belgian study Authors S. Karamaria2, N. Ranguelov3, P. Hansen4, V. De Boe5, P. Verleyen6, J. Vande Walle1,2, L. Dossche2, A. Bael7,8 1Department of Pediatric Nephrology, UZ Gent, Ghent, 2Ghent University, 3Department of Pediatrics, Cliniques Universitaires St-Luc, Université Catholique de Louvain, Brussels, 4Department of Pediatrics, CHU Tivoli, La Louvière, 5Department of Urology, UZ Brussel, Brussels, 6Department of Urology, AZ Groeninge, Kortrijk, 7Department of Pediatrics, Pediatric Nephrology, ZNA Koningin Paola Kinderziekenhuis, Antwerp; 8Faculty of Medicine, University of Antwerp, Antwerp Background International guidelines have a consensus that stratification of nocturnal enuresis (NE) into non-monosymptomatic (NMNE) and monosymptomatic (MNE) is mandatory at intake to optimize therapeutic approach. This stratification is based on clinical parameters (presence or absence of Lower Urinary Tract Symptoms (LUTS) respectively). To identify clinical parameters a checklist (Clinical Management Tool (CMT)) and/or voiding diaries based on home recordings can be used. However, these recordings can be time consuming and difficult for the family. Moreover, the added value to the CMT, especially in treatment naïve patients, is rather expert opinion than evidence based. Methods The aim of this study run in 7 Belgian Hospitals, was to document in treatment naïve NE patients >5 years: 1) The prevalence of MNE vs NMNE 2) the added value and correlation of CMT and/or diary in differentiating NE. Two study visits were scheduled: At visit 1 CMT was obtained, after a thorough medical history and basic assessments. If daytime incontinence and/or LUTS were identified, the diagnosis was NMNE. After the 1st study visit, a 2day voiding diary (fluid intake, voiding volumes, incontinence) was registered at home. During the second study visit, this diary was evaluated; if the micturition frequency was >8 or <3 and/or there was daytime incontinence, the diagnosis was NMNE. Results In total 109 children were included, of which19 were lost in follow up. Mean age was 7,7 (±2); 62 were boys (68,9%) and 27 were girls (30%). 68 (75, 6%) were included at a non-University center. Based on the CMT 13 children were diagnosed as MNE (16,7%) and 75 children as NMNE (83,3%). Based on the diary 16 children were diagnosed as MNE (17,8%) and 74 children as NMNE (82,2%). 25 children (27,8%) had the same diagnosis with both methods Regarding the presence or not of LUTS we observed significant inconsistencies between the CMT and the diary. Specifically there was fair agreement between the two modalities for urge (κ=0,219), moderate agreement for daytime incontinence (κ=0,432) and no agreement for abnormal voiding frequency (8 voidings/day) between what the parents answered on the CMT and what they registered in the diary (κ=-0,057). Conclusion NMNE is more frequent than MNE in treatment naïve patients. CMT alone versus CMT + diary had a different sensitivity and specificity of identifying LUTS : in absence of validation of the importance by a therapeutic trial outcome, we state that we can only consider patients as MNE when and CMT and diary do not demonstrate LUTS

Growth, structural and plasma illumination properties of nanocrystalline diamond-decoratedgraphene nanoflakes

Decorating graphene nanoflakes with nanocrystalline diamond gives superior functioning for microplasma devices with long lifetime stability plasma illumination performances.</p