Very fast blind source separation by signal to noise ratio based stopping threshold for the SHIBBS/SJAD algorithm

This paper works on joint approximate diagonalization of simplified fourth order cumulant matrices for very fast and large scale blind separation of instantaneous mixing model sources. The JADE algorithm is widely accepted but only limited to small scale separation tasks. The SHIBBS algorithm calculates a fraction of the fourth order cumulant set and avoids eigenmatrix decomposition to reduce calculation cost. However, it was seen to be slower than JADE at the time of its first publication and is hence less known. On the other hand, the SJAD algorithm using the same approach is shown to be very fast. This paper studies the iteration convergence criterion and proposes to use a signal to noise ratio based iteration stopping threshold approach. The improved SHIBBS/SJAD algorithm is very fast, and capable of large scale separation. Experimental separation comparisons between the SHIBBS/SJAD and FastICA are presented.     

Laser Surface Nitriding of Ti-6A1-4V Titanium Alloy

Titanium and its alloys are known for their high specific strength as well as fatigue and corrosion resistance. However, they suffer from poor wear and friction resistance, limiting their use in tribological applications. Nitriding of these materials may be carried out favourably to harden them and thus to improve both wear and friction resistance. The laser nitriding process involves using the intense energy of the laser to melt the surface in a nitrogen comprising atmosphere. This results in creation of a very hard layer consisting of dendritic structures of nitride. But the non-uniformity of the melt pool and cracks in the nitrided layers have been generally observed. Our study deals with the results of Ti-6Al-4V laser surface nitriding and with the effects of a sample preheating on the cracks generation.     

Microenvironmental factors regulate Ly-6 A/E expression on PyV-transformed BALB/c 3T3 cells

Ouabain-induced changes of the free cytoplasmic Na+ concentration ([Na+]i) were monitored in aggregates of cells prepared from beta-cell-rich pancreatic mouse islets and the results were compared with the total islet content of sodium. The steady-state [Na+]i was lower in 20 mM glucose (11 mM) than in 3 mM glucose (14 mM). In the presence of 3 mM glucose the addition of 1 mM ouabain resulted in a rise in [Na+]i with an initial rate of 1.5 mM/min. However, the increase of total sodium corresponded to 2.8 mM/min, suggesting that rapid binding and/or sequestration of Na+ are prominent features for pancreatic beta-cells. Elevation of the glucose concentration to 20 mM increased the rate of ouabain-dependent rise of [Na+]i. The effect of glucose was mimicked by 1 mM tolbutamide or 100 microM carbachol and was counteracted by 100 nM of the alpha 2-adrenergic agonist clonidine. Glucose also accelerated the lowering of [Na+]i after withdrawal of ouabain. In promoting not only the entry but also the extrusion of Na+, glucose actually enhances the turnover of the ion in pancreatic beta-cells.     

Crosslinked polyethers as media for ionic conduction

A broad outline is given of a comprehensive investigation dealing with solid polymeric electrolytes containing ionic species. These materials are based on various types of polyethers (homopolymers, block and graft copolymers) crosslinked via urethane chemistry and either filled with a salt or transformed into ionomers with the anions attached to the chains. The properties studied were specific volume, swelling, glass transition temperature, viscoelasticity, ionic conductivity, transport numbers, magnetic relaxation of nuclei from both the polymer chains and the ions, and redox stability. Mechanisms and models are proposed to explain chain partitioning by cations and the mode of ionic transport. An all-solid-state battery was prepared with one of these materials to prove its good performance.     

Evolutionary design of discrete controllers for hybrid mechatronic systems

This paper investigates the issue of evolutionary design of controllers for hybrid mechatronic systems. Finite State Automaton (FSA) is selected as the representation for a discrete controller due to its interpretability, fast execution speed and natural extension to a statechart, which is very popular in industrial applications. A case study of a two-tank system is used to demonstrate that the proposed evolutionary approach can lead to a successful design of an FSA controller for the hybrid mechatronic system, represented by a hybrid bond graph. Generalisation of the evolved FSA controller to unknown control targets is also tested. Further, a comparison with another type of controller, a lookahead controller, is conducted, with advantages and disadvantages of each discussed. The comparison sheds light on which type of controller representation is a better choice to use in various stages of the evolutionary design of controllers for hybrid mechatronic systems. Finally, some important future research directions are pointed out, leading to the major work of the succeeding part of the research.     

Applying SVMs and weight-based factor analysis to unsupervised adaptation for speaker verification

This paper presents an extended study on the implementation of support vector machine (SVM) based speaker verification in systems that employ continuous progressive model adaptation using the weight-based factor analysis model. The weight-based factor analysis model compensates for session variations in unsupervised scenarios by incorporating trial confidence measures in the general statistics used in the inter-session variability modelling process. Employing weight-based factor analysis in Gaussian mixture models (GMMs) was recently found to provide significant performance gains to unsupervised classification. Further improvements in performance were found through the integration of SVM-based classification in the system by means of GMM supervectors.This study focuses particularly on the way in which a client is represented in the SVM kernel space using single and multiple target supervectors. Experimental results indicate that training client SVMs using a single target supervector maximises performance while exhibiting a certain robustness to the inclusion of impostor training data in the model. Furthermore, the inclusion of low-scoring target trials in the adaptation process is investigated where they were found to significantly aid performance.     

Comments on: Deville and Särndal’s calibration: revisiting a 25 years old successful optimization problem

TEST - We provide a brief discussion on the development of model calibration techniques and optimal calibration estimation in survey sampling and its relation to Deville and Särndal’s...     

Three dimensional transient analysis of the installation of marine cables

Summary A numerical solution for the three dimensional transient motion of a marine cable during installation is presented for the case of a cable laying vessel arbitrarily chaning speed and direction while paying out cable with seabed slack. The cable transient behaviour is governed by the numerical solution of a set of non-linear partial differential equations with the solution methodology incorporating both spatial and temporal integration. The space integration is carried out by dividing the cable inton straight elements with equilibrium relationships and geometric compatibility equations satisfied for each element. The position of each element is described by its elevation and azimuth angles and, therefore, a system of 2n non-linear ordinary differential equations is established. The time integration of this set of equations is performed using a high order Runge-Kutta technique. Results are presented fro the cable tension and element elevation and azimuth angles as functions of time and for transient cable geometries when the cable ship executes horizontal planar manoeuvres.List of symbols A _t, A_n, A_b tangential, normal and binormal components of cable element acceleration vector - A _c (s, t) cable element acceleration vector - C _D ,C _f normal and tangential friction drag coefficients - C _m added mass coefficient - D _n n,D _b b,D _t t normal, binormal and tangential drag forces - d cable diameter - G _i (t) constant of integration - g gravitational acceleration - H hydrodynamic constant of the cable - I, J, K inertial system unit vectors - i, j, k tow vessel system unit vectors - L _i length of the cable element - N, B, T normal, binormal and tangential node forces - n number of straight elements - 2N _i /L _i , 2B _i /L _i geometric stiffness terms - OXYZ inertial system - oxyz system attached to the tow vessel - oxyz local system - R _c (s, t) vector position of a cable element - r _o(t),r _c (s, t) ship and cable element position vectors - cable element velocity vector - cable element acceleration vector - ship speed - ship acceleration - s unstretched distance along the cable - T t effective tension - T _i (s, t) axial tension in cable elementi - T _{n, 0} = –L _n H( _n ) axial tension in the beginning of elementn - T _ship(t) cable top force - 0054xx _{s, t} true axial force - t, n, b tangent, normal and binormal unit vectors - V _p ⁰ cable pay out rate - V ₀ initial ship speed - V _t ,V _n ,V _b tangential, normal and binormal components of cable element velocity vector - V _c (s, t),A _c (s, t) velocity and acceleration vectors of a cable element - w cable weight in sea water per unit length - w j self weight - X(s, t), Y(s, t) Z(s, t) functions describing cable geometric configuration - final ship azimuth direction - sea water density - _c cable physical mass per unit length - _c A _c d'Alembert force - added inertia - time taken for the ship to change heading - = (s, t), = (s, t) azimuth and elevation angles - _i , _i azimuth angle and elevation angle     

Three-dimensional physics-based registration of pelvic system using 2D dynamic magnetic resonance imaging slices

This paper introduces a method for dynamic 3D registration of female pelvic organs using 2D dynamic magnetic-resonance images (MRIs). The aim is to provide a better knowledge and understanding of pathologies such as prolapsus or abnormal mobility of tissues. 2D dynamic MRI sequences are commonly used in nowadays clinical routines in order to evaluate the dynamic of organs, but due to the limited view, subjectivity related to human perception cannot be avoided in the diagnoses. A novel method for 2D/3D registration is proposed combining 3D finite element models with a priori knowledge of boundary conditions, in order to provide a 3D extrapolation of the dynamic of the organs observed in a single 2D MRI slice. The method is applied to the four main structures of the female pelvic floor (bladder, vagina, uterus and rectum), providing a full 3D visualisation of the organs' displacements. The methodology is evaluated with two patient-specific data sets of volunteers presenting no pelvic pathology, and a sensitivity study is performed using synthetic data. The resulting simulations provide an estimation of the dynamic 3D shape of the organs facilitating diagnosis compared with 2D sequences. Moreover, the method follows a protocol compatible with current clinical constraints presenting this way potential short term medical applications.