Construction and qualification of the pre-series MQM superconducting quadrupoles for the LHC insertions

The LHC insertions will be equipped with individually powered MQM superconducting quadrupoles, produced in three versions with magnetic lengths of 2.4 m, 3.4 m, and 4.8 m. The quadrupoles feature a 56 mm aperture coil, designed on the basis of an 8.8 mm wide Rutherford-type NbTi cable for a nominal gradient of 200 T/m at 1.9 K and 5390 A. A total of 96 quadrupoles are in production in Tesla Engineering, UK. In this report we describe the construction of the pre-series MQM quadrupoles and present the results of the qualification tests.     

A jaw model for the study of the mandibular flexure taking into account the anisotropy of the bone

Knowledge of the complex biomechanical behaviour of the human mandible is of great importance in various clinical situations. The biomechanical and physical behaviour of mandibles have been investigated by different approaches. Some research have been done to evaluate the functional character of mandibles. Methods such as indirect measurement of deformations performed by intraoral appliances and by holographic interferometry have being employed. Other studies evaluated the mechanical properties and material parameters of small cubes of mandibles. One disadvantage of the experiments using strain gauges or holographic interferometry is the inability to determine strains at defined positions within the specimen. Additionally, research in biomechanics by these methods is limited to surface deformations and neither stresses nor dislocations can be measured.In the course of this study, we have investigated the mandibular flexure under mechanical loads using the results of a Finite Element Analysis (FEA). In order to obtain more accurate and realistic results, the bone anisotropy has being taken into account for the mathematical modelling of the jaw.The objective of this study was to establish a non-invasive procedure to predict precisely the complex biomechanical reactions of mandibles under mechanical loading. In order to achieve this aim, a comparison of the numerical data obtained with the experimental values of previous studies was performed. It showed a good correlation between in vitro measurements and mathematical modelling. Then the Finite Elements (FE) model was used to evaluate some mandibular movements (corporal approximation, dorsoventral shear, and corporal rotation in edentulous subjects).It is concluded that the applied procedure of generating the FE model is a valid and accurate non-invasive method to predict different parameters of the complex biomechanical behaviour of human mandibles.     

Strategies for the identification of urinary calculus by laser induced breakdown spectroscopy

The present work studies two different strategies to identify urinary calculus. On one hand, (linear or parametric and rank or non-parametric) correlation methods using a μ-LIBS system are studied. On the other hand, elemental ratios of reference materials are determined by using a higher-energy laser and an Echelle spectrograph with an ICCD camera, although without microscope. A data-treatment method was applied for each system and real samples of kidney stones - previously analyzed by IR spectroscopy - were used for reliable evaluation of two identification strategies.     

Properly -realizable groups

A finitely presented group is said to be properly -realizable if there exists a compact -polyhedron with and whose universal cover has the proper homotopy type of a (p.l.) -manifold with boundary. In this paper we show that, after taking wedge with a -sphere, this property does not depend on the choice of the compact -polyhedron with . We also show that (i) all -ended and -ended groups are properly -realizable, and (ii) the class of properly -realizable groups is closed under amalgamated free products (HNN-extensions) over a finite cyclic group (as a step towards proving that -ended groups are properly -realizable, assuming -ended groups are).

     

Dynamics of large turbulent structures in a steady breaker

The flow near the leading edge of a steady breaker has been studied experimentally using Bubble Image Velocimetry (BIV) with the aim of characterizing the dynamics of the large eddies responsible for air entrainment. It is well reported in the literature, and confirmed by our measurements of the instantaneous velocity field, that this flow shares some important features with the turbulent shear-layer formed between two parallel semi-infinite streams with different velocities. Namely, the formation of a periodic array of coherent vortices, the constant convective velocity of those vortices, the linear relation between their size and their downstream position and the self-similar structure of both mean velocity profiles and Reynolds shear stresses. Nonetheless, important differences exists between the dynamics of the large eddies in a steady breaker and those in a free shear-layer. Particularly, the convective velocity of these large structures is slower in a steady breaker and, consistent with this, their growth rates are larger. A physical interpretation of these differences is provided together with a discussion of their implications. To support our measurements and conclusions, we present a careful analysis of the accuracy of the BIV technique in turbulent flows with large bubbles.     

Effects of Collar Permeability on the Field Quality of the Large Aperture Quadrupoles for the LHC

The LHC contains a number of large aperture quadrupoles (MQY) in the insertions. The acceptance of these magnets was based on warm magnetic measurements performed before delivery to CERN. During the series production of the MQY quadrupoles, the permeability of the collars drifted from the nominal value, and effects on the transfer function and multipole components became evident. To study the effects on the magnetic field, variable permeability of the stainless-steel collars as a function of local field and temperature was introduced into a numerical model. Comparing the results with measured data, we could isolate the contribution of permeability deviation on the magnetic field quality. The extrapolation of transfer function and field multipoles to operating temperature and current gives the necessary offsets, which are compared with measurements on a reduced set of magnets.     

Battery state-of-charge estimator using the SVM technique

State-of-charge (SOC) is the equivalent of a fuel gauge for a battery pack in an electric vehicle. Determining the state-of-charge becomes an important issue in all battery applications including electric vehicles (EV), hybrid electric vehicles (HEV) or portable devices. The aim of this innovative study is to estimate the SOC of a high capacity lithium iron phosphate (LiFePO₄) battery cell from an experimental data-set obtained in the University of Oviedo Battery Laboratory (UOB Lab) using support vector machine (SVM) approach. The SOC of a battery cannot be measured directly and must be estimated from measurable battery parameters such as current, voltage or temperature. An accurate predictive model able to forecast the SOC in the short term is obtained. The agreement of the SVM model with the experimental data-set confirmed its good performance.     

Fabrication of the pre-series wide aperture superconducting quadrupoles for the LHC insertions

Individually powered superconducting quadrupoles with a coil bore of 70 mm will be installed in the LHC insertions, in areas where increased geometrical acceptance and improved field quality are required. The quadrupoles feature a four-layer coil, designed on the basis of two graded 8.3 mm wide Rutherford-type NbTi cables. The magnets have a magnetic length of 3.4 m and a nominal gradient of 160 T/m at 4.5 K and 3610 A. A total of 26 quadrupoles are in production at ACCEL Instruments (Germany). In this report, we present the experience in fabrication of the pre-series magnets and the results of the initial qualification tests.     

Study of posterolateral lumbar arthrodesis by means of a finite element model

Posterolateral lumbar arthrodesis consists in the fixation of the lumbar vertebrae pedicles by means of bars and screws. It is indicated in all those cases in which instability exists previous to the surgery, or in those other cases in which the instability has been caused by the need of bone resections that put the articulations structures in danger.The pedicle fixation of the lumbar arthrodesis is a great advance in the lumbar surgery. It contributes to achieve a stable and biologic fusion. The aim of the present research is the analysis of the contact problem that exists between the screw and the bone as one of the key points to control in order to achieve a good future stability of the arthrodesed spine.In order to achieve such aim, a Finite Elements Model (FEM) of the spine was performed. Such a model was obtained using a computer vision technique that creates 3D bodies using computed tomographies of the sacrum and vertebrae L4 and L5. Not only the bone bodies have been modeled, but also the intervertebral discs that act as the joints of the bones. In order to obtain a complete simulation of the lumbar region the titanium screws and bars have been modeled too.The study of the influence of the contact between bone and screw in the biomechanical behavior of the lumbar column has been studied applying several load conditions simulating different kinds of typical movements of the column. Finally, the stresses on the different elements of the lumbar structure and the relative movements between bone and screw as well as the conclusions of this research are also expounded.