Optimal control theory based design of elasto-magnetic metamaterial

A method to design a new type of metamaterial is presented. A two-step strategy to define an optimal long-range force distribution embedded in an elastic support to control wave propagation is considered. The first step uses a linear quadratic regulator (LQR) to produce an optimal set of long-range interactions. In the second step, a least square passive approximation of the LQR optimal gains is determined. The paper investigates numerical solutions obtained by the previously described procedure. Finally, we discuss physical and engineering implications and practical use of the present study

Twin-waves propagation phenomena in magnetically-coupled structures

The use of magnetic dipoles embedding in an elastic support introduces long-range interaction forces. This is a completely new paradigm in structural mechanics, classically based on local short-range particle interaction. The features of long-range forces produce very new mechanical coupling effects. This paper examines the case in which two identical rod-like structures, each with a dipole distribution embedded, vibrate side by side. Waves generated in one of the rods propagate also in the second and vice versa creating a new effect we name twin-waves. The present investigation unveils the existence of an infinite number of propagation modes even in one-dimensional infinite structures, a new and unus al behaviour in classical waveguides. The physics behind this phenomenon is further investigated also by numerical simulations

Long-range retarded elastic metamaterials: wave-stopping, negative, and hypersonic or superluminal group velocity

This paper investigates new phenomena in elastic wave propagation in metamaterials, characterised by long-range interactions. The kind of waves borne in this context unveil wave-stopping, negative group velocity, instability and hypersonic or superluminal effects, both for instantaneous and for nonlocal retarded actions. Closed form results are presented and a universal propagation map synthesizes the expected properties of these materials. Perspectives in physics, engineering and social dynamics are discussed

An unusual case of an intramuscular lipoma of the biceps brachii

Lipomas are common benign neoplasms consisting of mature fatty tissue. They are usually of roundish or ovoid shape and are situated in a single anatomical region. They most frequently occur on the back and in the extremities. Most lipomas are subcutaneous and require no imaging evaluation. When deep, large and unusual in location, MRI can identify and localise these tumours and is the best exploration to differentiate lipoma and lipo-sarcoma. We describe a case of a patient with an intramuscular lipoma of the biceps brachii.Key words: Intramuscular, lipoma, biceps brachi

Variational control approach to energy extraction from a fluid flow

Energy harvesting from the environment is an important aspect of many technologies. The scale of energy capturing and storage can involve the power range from mWatt up to MWatt, depending on the used devices and the considered environments (from ambient acoustic and vibration to ocean wave motion, or wind). In this paper, the wind turbine energy harvesting problem is approached as an optimal control problem, where the objective function is the absorption of an amount of energy in a given time interval by a fluid-flow environment, that should be maximized. The interest relies on outlining general control models of fluid-flow-based extraction plants and identifying an optimum strategy for the regulation of an electrical machine to obtain a maximum-efficiency process for the related energy storage. The mathematical tools are found in the light of optimal control theory, where solutions to the fundamental equations are in the frame of Variational Control (the basis of the Pontryagin optimal control theory). A special problem, named Optimally Controlled Betz’s Machine OCBM-optimal control steady wind turbine, is solved in closed form, and it is shown that, in the simpler steady case, it reproduces the maximum efficiency machine developed in Betz’s theory

OPTYRE—Real time estimation of rolling resistance for intelligent tyres

The study of the rolling tyre is a problem framed in the general context of nonlinear elasticity. The dynamics of the related phenomena is still an open topic, even though few examples and models of tyres can be found in the technical literature. The interest in the dissipation effects associated with the rolling motion is justified by their importance in fuel-saving and in the context of an eco-friendly design. However, a general lack of knowledge characterizes the phenomenon, since not even direct experience on the rolling tyre can reveal the insights of the correlated different dissipation effects, as the friction between the rubber and the road, the contact kinematics and dynamics, the tyre hysteretic behaviour and the grip. A new technology, based on fibre Bragg grating strain sensors and conceived within the OPTYRE project, is illustrated for the specific investigation of the tyre dissipation related phenomena. The remarkable power of this wireless optical system stands in the chance of directly accessing the behaviour of the inner tyre in terms of stresses when a real-condition-rolling is experimentally observed. The ad hoc developed tyre model has allowed the identification of the instant grip conditions, of the area of the contact patch and allows the estimation of the instant dissipated power, which is the focus of this paper

Un cas de fracture luxation négligée du coude avec conservation de la fonction du coude

Les fractures luxations du coude sont rares et souvent mal tolérées chez les sujets jeunes actifs. Nous rapportons un cas de fracture-luxation du coude remontant à 20 ans. C'est un jeune de 35 ans, victime il y a 20 ans d'un traumatisme fermé, suite à une chute lors d'un match du football, de son coude gauche occasionnant une fracture-luxation du coude. Le patient a  refusé une intervention chirurgicale avec une auto-rééducation. L'examen a mis en évidence une conservation de la fonction du coude. Un bilan  radiologique a montré une fracture luxation du coude avec remaniement de la palette humérale. Une abstention thérapeutique a été décidée devant l'ancienneté de la fracture-luxation et la gêne fonctionnelle minime  engendrée. Contrairement aux autres séries, la fracture-luxation dans notre cas était bien tolérée malgré le jeune âge du patient

Traitement chirurgical par plaque à compression des fractures de Galeazzi chez l’adulte: À propos de 28 cas

La fracture de Galeazzi associe une fracture diaphysaire du radius ou des deux os de l'avant bras à une luxation de l'articulation radio ulnairedistale. Décrite en 1934, sa fréquence varie chez l'adulte entre 2,7% et 6,8% de l'ensemble des fractures de l'avant bras. Le traitement admis defaçon consensuel chez l'adulte est chirurgical reposant sur une ostéosynthèse stable par une plaque vissée de compression dynamique associée ou non à un embrochage de la radio ulnaire distale. Nous rapportons dans notre étude les résultats cliniques de 28 patients colligés au service de traumatologie et orthopédie A du CHU Hassan II de Fès sur une période de 06 ans. L'âge moyen de nos patients était de 30 ans avecprédominance masculine de 90%; tous nos patients ont présenté un traumatisme de poignet lors d'un accident de sport. Le côté droit était atteint dans 75 % des cas. Le bilan radiologique objectiva une fracture diaphysaire du raduis associée à une luxation radio ulnaire distale; nous avons adopté la classification de de Mansat. Le traitement a consisté en une synthèse par une plaque vissée dynamique associée à un   embrochage transversal chez six patients qui ont présenté une instabilité de la radio ulnaire distale. L'immobilisation par attelle plâtrée postérieure BABP était de mise. Après un recul de 36 mois, nos résultats ont été très satisfaisants suivant le score de Mestdagh, avec bonne récupération de la mobilité du poignet et reprise de toute activité sportive

Aerobic training and angiogenesis activation in patients with stable chronic heart failure: a preliminary report.

The pathophysiology of chronic heart failure (CHF) involves multiple hystologic and molecular alterations. To determine the effects of physical training on circulating endothelial progenitor cells (EPCs), angiogenesis (angiogenin, angiopoietin-1 and -2, VEGF, Tie-2, SDF-1α) and inflammation (IL-6, CRP), we compared data obtained from 11 CHF pts before and after 3 months aerobic exercise training, to those from 10 non trained CHF pts (CHF-C group, age 64 + 2 years, NYHA 2). At the end of the study, EPCs count and AP-2 serum levels significantly increased in the CHF-TR group. These preliminary data suggest a significant effect of even a short program of physical training on angiogenic activation and endothelial dysfunction

Acceptability, Feasibility and Preliminary Evaluation of a Novel, Personalised, Home based Physical Activity Intervention for Chronic Heart Failure (Active-at-Home-HF)::A Pilot Study

Purpose: Less than 10% of heart failure patients in the UK participate in cardiac rehabilitation programmes. The present pilot study evaluated feasibility, acceptability and physiological effects of a novel, personalised, home-based physical activity intervention in chronic heart failure. Methods: Twenty patients (68±7 years old, 20% females) with stable chronic heart failure due to reduced left ventricular ejection fraction (31±8 %) participated in a single group, pilot study assessing the feasibility and acceptability of a 12-week personalised home-based physical activity intervention aiming to increase daily number of steps by 2000 from baseline (Active-at-Home-HF). Patients completed cardiopulmonary exercise testing with non-invasive gas exchange and haemodynamic measurements and quality of life questionnaire pre- and post-intervention. Patients were supported weekly via telephone and average weekly step count data collected using pedometers. Results: 43 patients were screened and 20 recruited into the study. Seventeen patients (85%) completed the intervention, and 15 (75%) achieved the target step count. Average step count per day increased significantly from baseline to 3 weeks by 2546 (5108±3064 to 7654±3849 P=0.03, n=17), and was maintained until week 12 (9022±3942). Following completion of the intervention, no adverse events were recorded, quality of life improved by 4 points (26±18 vs. 22±19). Peak exercise stroke volume increased by 19% (127±34 vs 151±34 m/beat, P=0.05), while cardiac index increased by 12% (6.8±1.5 vs. 7.6±2.0 L/min/m2, P=0.19). Workload and oxygen consumption at anaerobic threshold also increased by 16% (49±16 vs. 59±14 watts, P=0.01) and 10% (11.5±2.9 vs. 12.8±2.2 ml/kg/min, P=0.39). Conclusion: The Active-at-Home-HF intervention is feasible, acceptable and effective for increasing physical activity in CHF. It may lead to improvements in quality of life, exercise tolerance and haemodynamic function