In this study the non-linear hereditariness of knee tendons and ligaments is framed in the context of stochastic mechanics. Without losing the possibility of generalization, this work was focused on ...knee Anterior Cruciate Ligament (ACL) and the tendons used in its surgical reconstruction. The proposed constitutive equations of fibrous tissues involves three material parameters for the creep tests and three material parameters for relaxation tests. One-to-one relations among material parameters estimated in creep and relaxations were established and reported in the paper. Data scattering, observed with a novel experimental protocol used to characterize the mechanics of the tissue, was modelled as the outcome of the random mechanical parameters. The numerical example proposed in the paper shows that for an assigned probability density function of the material random parameters, the parameters of the probability density function (pdf) may be obtained by a statistical analysis of the experimental data.
The complex inhomogeneous architecture of the human meniscal tissue at the micro and nano scale in the absence of artefacts introduced by sample treatments has not yet been fully revealed. The ...knowledge of the internal structure organization is essential to understand the mechanical functionality of the meniscus and its relationship with the tissue's complex structure. In this work, we investigated human meniscal tissue structure using up-to-date non-invasive imaging techniques, based on multiphoton fluorescence and quantitative second harmonic generation microscopy complemented with Environmental Scanning Electron Microscopy measurements. Observations on 50 meniscal samples extracted from 6 human menisci (3 lateral and 3 medial) revealed fundamental features of structural morphology and allowed us to quantitatively describe the 3D organisation of elastin and collagen fibres bundles. 3D regular waves of collagen bundles are arranged in "honeycomb-like" cells that are comprised of pores surrounded by the collagen and elastin network at the micro-scale. This type of arrangement propagates from macro to the nanoscale.
Microwave reflectometry, having its origins in ionosphere probing techniques to evaluate electronic density, has become one of the most important diagnostics for the same quantity in fusion plasmas. ...Reflectometry will play a major role in next-generation machines, in particular in DEMO, where it is expected to provide plasma positioning, shaping, and tracking data. The ability to have an ever-increasing comprehensive description of reflectometry is particularly important since it allows us to assess the measuring capabilities of existing experimental systems and to predict the performance of new diagnostic concepts based on probing waves. Furthermore, wave propagation in a thermonuclear plasma with fluctuating electronic densities is far from straightforward and the need for a numerical full-wave treatment becomes fundamental. We will present the reader with the fundamentals of this technique and introduce the usage and evolution of FDTD in reflectometry, using as an example, the synthetic diagnostics setup that uses the family of REFMUL* codes, which is employed in the assessment of the performance of several reflectometry systems in different fusion machines.
A major modification of the RFX-mod toroidal load assembly has been decided in order to improve passive MHD control and to minimize the braking torque on the plasma, thus extending the operational ...space in both RFP and Tokamak configurations. With the removal of the vacuum vessel, the support structure will be modified in order to obtain a new vacuum-tight chamber and the first wall tiles will be directly in front of the passive stabilizing shell inside of it, so increasing both the poloidal cross section and the plasma-shell proximity.
This implies the design of a new vacuum fit electromagnetic measurement system. The new local probes will be installed in vacuum onto the copper shell, behind the graphite tiles, and shall operate up to a maximum temperature of 180 °C to allow for baking cycles for first wall conditioning. Because of the reduced room available, tri-axial pickup probes have been designed, with the additional advantage of allowing the minimization of alignment errors.
The paper describes the detailed design of the new probe set, in particular highlighting advantages and effectiveness of different probe solutions. Preliminary tests carried out on local probe prototypes to characterize their electromagnetic behaviour are also reported.
•An initial concept and basis for the DEMO diagnostic and control system is presented.•The main control issues for the burn phase of the plasma have been allocated to a reduced set of diagnostics and ...actuators.•A set of 10 high level control requirements is formulated to guide the further developments.•Details on the current set of diagnostic methods and channels, as well as an outline of the integration approaches into the tokamak, are given.
An initial concept for the plasma diagnostic and control (D&C) system has been developed as part of European studies towards the development of a demonstration tokamak fusion reactor (DEMO). The main objective is to develop a feasible, integrated concept design of the DEMO D&C system that can provide reliable plasma control and high performance (electricity output) over extended periods of operation. While the fusion power is maximized when operating near to the operational limits of the tokamak, the reliability of operation typically improves when choosing parameters significantly distant from these limits. In addition to these conflicting requirements, the D&C development has to cope with strong adverse effects acting on all in vessel components on DEMO (harsh neutron environment, particle fluxes, temperatures, electromagnetic forces, etc.). Moreover, space allocation and plasma access are constrained by the needs for first wall integrity and optimization of tritium breeding. Taking into account these boundary conditions, the main DEMO plasma control issues have been formulated, and a list of diagnostic systems and channels needed for plasma control has been developed, which were selected for their robustness and the required coverage of control issues. For a validation and refinement of this concept, simulation tools are being refined and applied for equilibrium, kinetic and mode control studies.
•Definition of space/time requirements for equilibrium and shape control system.•Definition of space/time requirements for MHD mode active control system.•Definition of space/time requirements for ...plasma physics investigations.•Two alternative layouts of sensors are compared to the present configuration.•A preliminary design of a magnetic field triaxial sensor is presented.
A major refurbishment of the toroidal load assembly is under study to extend the operational space of RFX-mod in both RFP and Tokamak configurations. It includes the removal of the vacuum vessel to increase the plasma-shell proximity and modifications of the support structure to obtain a new vacuum-tight chamber. This entails the design of a new electromagnetic measurement system, taking into account the requirements of both the equilibrium and MHD control system and physics analyses requirements in both RFP and shaped Tokamak configurations. The spatial resolution is constrained by the number of graphite tiles, 28 (poloidal)x72 (toroidal), which cover the inner surface of the toroidal vacuum chamber. Alternative layouts of 4x72 and 7x72 are being considered to assure the calculation of the MHD mode spectrum up to (m=0,1,2 or 3; n=0,…,±35). A substantial advantage in terms of harmonic spectrum reconstruction is expected also in case of sensor faults with respect to the present 4x48 arrangement. Moreover, 12 poloidal arrays will include 14 sensors to compute the harmonic content needed by the plasma boundary reconstruction algorithm (m=0,…,6). Due to the reduced room between the copper shell and the graphite tiles, the design of triaxial, vacuum fit pickup probes have started also for their convenience in compensating alignment errors.
This article aims to discuss an experience narrative that occurred in a unit of a Federal Educational Institute, located at Rio de Janeiro state, in which was proposed an activity based on the ...Christophe Dejours psychodynamic theory of work. The activity was proposed to nine workers with different careers, employment bonds and professions. Besides, it was accomplished in seven meetings, lasting two months. The idea of this activity was based on the concerns detected, mainly related to moral harassment, during social work and psycological care. The activities were elaborated along with the participants, inspired by Christophe Dejours´s theory of work, Vincent de Gaulejac´s concerns about the insertion of managerialist ideology, mainly on the public services since 1995, and the changes related to work relations since the 1970’s. The data produced on the activities was analised using the content analisys method proposed by Bardin.
A series of techniques is presented that has been developed to optimize the output magnetic field of the feedback control system on the RFX-mod reversed field pinch device. With the aim of minimizing ...the harmonic distortion and correcting localized error fields, these methods should be lightweight for real-time application and effective in improving the performance of a system that is routinely used for active control of magnetohydrodynamic plasma instabilities. The implementation of simple, linear algebra based, real-time optimization methods will be described along with proof of the beneficial effects sought. The focus of this paper is set on a spurious harmonics reduction technique based on the decoupling of sensors and actuators; a description of its derivation will be given together with the implementation in the control loop. A similar procedure for the compensation of faulted actuators will also be mentioned.
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