Kinematic model identification of industrial manipulators

The aim of the work presented in this paper is to improve the off-line programming capability of industrial robots by improving their accuracy. Rather than impose more strict manufacturing tolerances, it is widely accepted that a method of identifying kinematic parameters specific to each individual robot provides a cost effective way of improving accuracy. A procedure is presented for identification of actual kinematic parameters, which uses the plane of rotation and centre of rotation introduced by Stone. The procedure differs from that of Stone in that it makes use of the radius of rotation and also introduces a translation of the plane of rotation along the axis of rotation. This allows for the direct identification of the D–H model parameters which are more widely accepted and easier to interpret than the S model parameters. It is shown that, unlike the original method of Stone, the new procedure can also deal with the situation when two consecutive joint axes are parallel. The method is validated on both simulated data and real measured data for a Puma 560 robot, showing an improvement in positioning accuracy of around 80%.     

Enhancement of sparse 3D reconstruction using a modified match propagation based on particle swarm optimization

Sparse 3D reconstruction, based on interest points detection and matching, does not allow to obtain a suitable 3D surface reconstruction because of its incapacity to recover a cloud of well distributed 3D points on the surface of objects/scenes. In this work, we present a new approach to retrieve a 3D point cloud that leads to a 3D surface model of quality and in a suitable time. First of all, our method uses the structure from motion approach to retrieve a set of 3D points (which correspond to matched interest points). After that, we proposed an algorithm, based on the match propagation and the use of particle swarm optimization (PSO), which significantly increases the number of matches and to have a regular distribution of these matches. It takes as input the obtained matches, their corresponding 3D points and the camera parameters. Afterwards, at each time, a match of best ZNCC value is selected and a set of these neighboring points is defined. The point corresponding to a neighboring point and its 3D coordinates are recovered by the minimization of a nonlinear cost function by the use of PSO algorithm respecting the constraint of photo-consistency. Experimental results show the feasibility and efficiency of the proposed approach.

     

Simple and fast convergent procedure to estimate recursive path analysis model

Behaviormetrika - BFGS procedure is classically used for the estimation of the parameters of a recursive Path Analysis model. In practice, BFGS does not present any problem of convergence. However,...     

X-Ray Diffraction and Mössbauer Studies of Nanostructured Ni40Fe60 Powder: Structure Defects and Hyperfine Structure

Journal of Superconductivity and Novel Magnetism - A nanostructured nickel–iron alloy having the Ni40Fe60 composition was prepared through the mechanical alloying of the elemental powders in...     

DNA detection with a water-gated organic field-effect transistor

A DNA sensor based on a water-gated organic field-effect transistor is described. The semiconductor is poly [3-(5-carboxypentyl)thiophene-2,5-diyl] onto which DNA probes are covalently grafted via NHS/EDC chemistry. Clear changes in the output characteristic of the device are observed upon DNA immobilization and after DNA hybridization. Experimental data point out the importance of the electrolyte Debye length that can screen negative DNA charges and impede transduction. For this reason, deionized water was used in order to increase the Debye length up to several hundreds of nanometers. In this case, a decrease in the off current was observed upon hybridization, whereas no significant change occurred when using saline solutions.     

Nonlinear free vibration of a shear deformable laminated composite annular elliptical plate

The nonlinear free vibration of a laminated composite annular elliptical plate with elliptically orthotropic plies is investigated. The effects of out-of-plane shear deformations, rotatory inertia and geometrical nonlinearity are taken into account. The problem is solved numerically using a new polynomially enriched sector elliptic p-element. The nonlinear equations of free motion are obtained using the harmonic balance method and solved iteratively by the linearized updated mode method. Results for the fundamental linear and nonlinear frequencies are obtained. Comparison is made with published results for a polar orthotropic annular plate and shows very good agreement. The minor semi-axis ratio, thickness ratio, moduli ratio, number of plies, layup sequence, and boundary conditions are shown to influence the hardening behavior.     

First-Principle Investigation of Structural,Electronic and Magnetic Properties in Mn<Subscript>2</Subscript>RhZ (Z = Si,Ge, and Sn) Heusler Alloys

Mn ₂-based Heusler compounds exhibit different types of anti-site disorder. The electronic structure and magnetism of Heusler alloys Mn₂RhZ (Z = Si, Ge, and Sn) have been studied by first-principle calculations. Mn₂RhSi and Mn₂RhGe are ordinary half-metallic ferrimagnetic metals at equilibrium lattice constants, with a magnetic spin moments obeys to the Slater-Pauling rule and spin polarization of 100 % at the Fermi energy. The tetragonal phase transformation is studied for Mn₂RhSn. The total magnetic moment of Mn₂RhSn in the tetragonal structure is higher compared to the other materials, which results in a large ΔM between the saturation moments of tetragonal and a cubic. The tetragonal Mn₂RhSn predicted to a high spin polarization ratio of 93 %. These properties of these materials are particularly interesting due to their perpendicular magnetic anisotropy (PMA), which was realized in thin films opening the door for application in STT magnetic random access memories (STT-MRAMs)     

Reactivity monitoring in ADS, application to the MYRRHA ADS project

Monitoring of reactivity in an ADS should be performed on-line with a simple, accurate and robust technique. Within the range of experimental reactor techniques, no single technique can be selected which meet these requirements. Therefore a combination of different techniques has to be chosen in a way that various off-line techniques serve as a calibration method for the on-line measurement technique. As an on-line measurement technique, the current-to-flux reactivity indicator is the most simple and robust solution. The current-to-flux reactivity indicator is based on the fact that in a sub-critical multiplying medium with a driving source the flux level is proportional to the driving source intensity, hence the beam current, and the reactivity level. However, since the proportionality constant depends on a number of core-dependent parameters and detector characteristics, this current-to-flux indicator has to be calibrated on a regular basis. For this calibration, one could benefit from the occurrence of accelerator beam trips to determine the reactivity level in dollars by means of a prompt jump analysis of the flux level change. Hence, the prompt jump reactivity indicator could act as a first calibration tool of the current-to-flux indicator. Since the prompt jump indicator still relies on the value for the effective delayed neutron fraction to determine reactivity level, complementary techniques have to be used to obtain a more accurate determination of the reactivity. Techniques based on reactor noise methods such as the RAPJA-technique which is a combination of the Rossi-Alpha method and a Prompt Jump Analysis can be used in this respect. In the future the bi-spectral ratio from the Cf-source driven noise analysis could be used for this purpose.     

Identification of Abundant and Functional dodecaRNAs (doRNAs) Derived from Ribosomal RNA

Using a modified RNA-sequencing (RNA-seq) approach, we discovered a new family of unusually short RNAs mapping to ribosomal RNA 5.8S, which we named dodecaRNAs (doRNAs), according to the number of core nucleotides (12 nt) their members contain. Using a new quantitative detection method that we developed, we confirmed our RNA-seq data and determined that the minimal core doRNA sequence and its 13-nt variant C-doRNA (doRNA with a 5′ Cytosine) are the two most abundant doRNAs, which, together, may outnumber microRNAs. The C-doRNA/doRNA ratio is stable within species but differed between species. doRNA and C-doRNA are mainly cytoplasmic and interact with heterogeneous nuclear ribonucleoproteins (hnRNP) A0, A1 and A2B1, but not Argonaute 2. Reporter gene activity assays suggest that C-doRNA may function as a regulator of Annexin II receptor (AXIIR) expression. doRNAs are differentially expressed in prostate cancer cells/tissues and may control cell migration. These findings suggest that unusually short RNAs may be more abundant and important than previously thought.