Efficiency of hysteresis rods in small spacecraft attitude stabilization

A semiempirical method for predicting the damping efficiency of hysteresis rods on-board small satellites is presented. It is based on the evaluation of dissipating energy variation of different ferromagnetic materials for two different rod shapes: thin film and circular cross-section rods, as a function of their elongation. Based on this formulation, an optimum design considering the size of hysteresis rods, their cross section shape, and layout has been proposed. Finally, the formulation developed was applied to the case of four existing small satellites, whose corresponding in-flight data are published. A good agreement between the estimated rotational speed decay time and the in-flight data has been observed

On Maximal Function on the Laguerre Hypergroup

2000 Mathematics Subject Classification: 42B20, 42B25, 42B35Let K = [0, ∞)×R be the Laguerre hypergroup which is the fundamental manifold of the radial function space for the Heisenberg group. In this paper we consider the generalized shift operator, generated by Laguerre hypergroup, by means of which the maximal function is investigated. For 1 < p ≤ ∞ the Lp(K)-boundedness and weak L1(K)-boundedness result for the maximal function is obtained.* V. Guliyev partially supported by grant of INTAS (Project 05-1000008-8157)

Generalized Sobolev Spaces of Exponential Type Associated with the Dunkl Operators

2000 Mathematics Subject Classification: 35E45In this paper we study generalized Sobolev spaces H^sG of exponential type associated with the Dunkl operators based on the space G of test functions for generalized hyperfunctions and investigate their properties. Moreover, we introduce a class of symbols of exponential type and their associated pseudodifferential operators related to the Dunkl operators, which act naturally on H^sG

Magnetic Attitude Control for Satellites in Polar or Sun-Synchronous Orbits

In this work, a new law for magnetic control of satellites in near-polar orbits is presented. This law has been developed for the UMPSat-2 microsatellite, which has been designed and manufactured by Universidad Politécnica de Madrid, Madrid. The control law is a modification of the B-dot strategy that enables the satellite to control the rotation rate. Besides, the satellite?s equilibrium state is characterized by having the rotation axis perpendicular to the orbit?s plane. The control law described in the present work only needs magnetometers and magnetorquers, as sensors and actuators, respectively, to carry out a successful attitude control on the spacecraft. A description of the analysis is included. Performance and applicability of the proposed method have been demonstrated by control dynamics together with Monte Carlo techniques and by implementing the control law in the UPMSat-2 mission simulator. Results show good performance in terms of acquisition and stability of the satellite rotation rate and orientation with respect to its orbit?s plane

Generalized Strichartz Inequalities for the Wave Equation on the Laguerre Hypergroup

Mathematics Subject Classification: 42B35, 35L35, 35K35In this paper we study generalized Strichartz inequalities for the wave equation on the Laguerre hypergroup using generalized homogeneous Besov-Laguerre type spaces

Predicting the pathogen of diabetic toe osteomyelitis by two consecutive ulcer cultures with bone contact

In this study, we investigate the accuracy of two consecutive ulcer cultures with bone contact compared to bone biopsy for the diagnosis of diabetic toe osteomyelitis. The same nurse and orthopaedic surgeon obtained all samples: sample A-1: bone contact swabbing through the ulcer; sample A-2: a second culture swabbing from the bone surface within 24 h; sample B: surgical bone biopsy in the operating theatre. The kappa statistic measure between samples A-1 and A-2 (bone contact swabs) indicated 82.35% agreement. The sensitivity, specificity, positive and negative predictive values of the two samples A compared to B were 96%, 79%, 92% and 88%, respectively, for the causative pathogen. These results were similar with prior antibiotic treatment, discordant bone surface swabs or with monomicrobial infections. As a conclusion, two consecutive diabetic toe cultures with bone contact accurately predict the pathogen of diabetic toe osteomyelitis in 90% of case

Hallux valgus, ankle osteoarthrosis and adult acquired flatfoot deformity: a review of three common foot and ankle pathologies and their treatments.

The pathogenesis of hallux valgus deformity is multifactorial. Conservative treatment can alleviate pain but is unable to correct the deformity. Surgical treatment must be adapted to the type and severity of the deformity. Success of surgical treatment ranges from 80% to 95%, and complication rates range from 10% to 30%.Ankle osteoarthrosis most commonly occurs as a consequence of trauma. Ankle arthrodesis and total ankle replacement are the most common surgical treatments of end stage ankle osteoarthrosis. Both types of surgery result in similar clinical improvement at midterm; however, gait analysis has demonstrated the superiority of total ankle replacement over arthrodesis. More recently, conservative surgery (extraarticular alignment osteotomies) around the ankle has gained popularity in treating early- to mid-stage ankle osteoarthrosis.Adult acquired flatfoot deformity is a consequence of posterior tibial tendon dysfunction in 80% of cases. Classification is based upon the function of the tibialis posterior tendon, the reducibility of the deformity, and the condition of the ankle joint. Conservative treatment includes orthotics and eccentric muscle training. Functional surgery is indicated for treatment in the early stages. In case of fixed deformity, corrective and stabilising surgery is performed. Cite this article: Crevoisier X, Assal M, Stanekova K. Hallux valgus, ankle osteoarthrosis and adult acquired flatfoot deformity: a review of three common foot and ankle pathologies and their treatments. EFORT Open Rev 2016;1:58-64. DOI: 10.1302/2058-5241.1.000015