A time delay controller for magnetic bearings

The control of systems with unknown dynamics and unpredictable disturbances has raised some challenging problems. This is particularly important when high system performance needs to be guaranteed at all times. Recently, the Time Delay Control has been suggested as an alternative control scheme. The proposed control system does not require an explicit plant model nor does it depend on the estimation of specific plant parameters. Rather, it combines adaptation with past observations to directly estimate the effect of the plant dynamics. A control law is formulated for a class of dynamic systems and a sufficient condition is presented for control systems stability. The derivation is based on the bounded input-bounded output stability approach using L sub infinity function norms. The control scheme is implemented on a five degrees of freedom high speed and high precision magnetic bearing. The control performance is evaluated using step responses, frequency responses, and disturbance rejection properties. The experimental data show an excellent control performance despite the system complexity

Has there been a recent shallowing of tropical cyclones?

Many aspects of tropical cyclone (TC) properties at the surface have been changing but any systematic vertical changes are unknown. Here, we document a recent trend of high thick clouds of TCs. The global inner-core high thick cloud fraction measured by satellite has decreased from 2002 to 2021 by about 10% per decade. The TC inner-core surface rain rate is also found to have decreased during the same period by a similar percentage. This suppression of high thick clouds and rain has been largest during the intensification phase of the strongest TCs. Hence, these two independent and consistent observations suggest that the TC inner-core convection has weakened and that TCs have become shallower recently at least. For this period, the lifetime maximum intensity of major TCs has not changed and this suggests an increased efficiency of the spin-up of TCs

National and regional seasonal dynamics of all-cause and cause-specific mortality in the USA from 1980 to 2016

In temperate climates, winter deaths exceed summer ones. However, there is limited information on the timing and the relative magnitudes of maximum and minimum mortality, by local climate, age group, sex and medical cause of death. We used geo-coded mortality data and wavelets to analyse the seasonality of mortality by age group and sex from 1980 to 2016 in the USA and its subnational climatic regions. Death rates in men and women ≥ 45 years peaked in December to February and were lowest in June to August, driven by cardiorespiratory diseases and injuries. In these ages, percent difference in death rates between peak and minimum months did not vary across climate regions, nor changed from 1980 to 2016. Under five years, seasonality of all-cause mortality largely disappeared after the 1990s. In adolescents and young adults, especially in males, death rates peaked in June/July and were lowest in December/January, driven by injury deaths

Facilitating Mechanical Design with Augmented Reality

By enhancing a real scene with computer generated objects, Augmented Reality (AR), has proven itself as a valuable Human-Computer Interface (HCI) in numerous application areas such as medical, military, entertainment and manufacturing. It enables higher performance of on-site tasks with seamless presentation of up-to-date, task-related information to the users during the operation. AR has potentials in design because the current interface provided by Computer-aided Design (CAD) packages is less intuitive and reports show that the presence of physical objects help design thinking and communication. This research explores the use of AR to improve the efficiency of a design process, specifically in mechanical design.Singapore-MIT Alliance (SMA

An Application of Augmented Reality (AR) in the Teaching of an Arc Welding Robot

Augmented Reality (AR) is an emerging technology that utilizes computer vision methods to overlay virtual objects onto the real world scene so as to make them appear to co-exist with the real objects. Its main objective is to enhance the user’s interaction with the real world by providing the right information needed to perform a certain task. Applications of this technology in manufacturing include maintenance, assembly and telerobotics. In this paper, we explore the potential of teaching a robot to perform an arc welding task in an AR environment. We present the motivation, features of a system using the popular ARToolkit package, and a discussion on the issues and implications of our research.Singapore-MIT Alliance (SMA

Determination of important flow characteristics for leak detection in water pipelines-networks

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.The accuracy of a leak detection method depends greatly on the flow and leak parameters in a given pipeline. This paper gives some insight into the flow characteristics around simulated small leaks. The present computational fluid dynamics studies have indicated clear distinctive features in fluid pressure and fluid acceleration that can be used for the early detection of small leaks with the magnitude of 2.75L/min in water distribution pipelines. The CFD study is based on the steady state turbulent flow simulation which was carried out for different pressure lines in 4-inch (100m) ID pipe. Based on the CFD simulation, it was found out that the pressure gradient in the vicinity of the leaks are quite large, hence a leak detection method based on pressure gradient measurement is proposed. In addition these simulation has shown axial flow acceleration in the flow centerline of the pipe have remarkable gradient which offers another leak detection method based on the use of accelerometer.dc201

SEARCH EFFICIENCY FUNCTION-PSO COMBINATION FORBLIND IMAGE RESTORATION

In this work we propose, for the first time, a combined method for blind image restoration. This combination is based on PSO and the integration in it of the search efficiency function that represent the optimal searching strategy elaborated by honeybees when searching for food, and its use for the first time in image processing, to carry out the restoration operation of the only blurred images and blurred and noisy ones. The results we got were excellent

Fistule carotido-caverneuse post-traumatique

Introduction : La fistule carotido-caverneuse (FCC) est une complication rare, mais grave des traumatismes craniofaciaux pouvant engager le pronostic fonctionnel oculaire et le pronostic vital. elle réalise une communication anormale entre le système artériel carotidien et le sinus caverneux.Buts : Rapporter un cas de FCC directe post-traumatique et étudier les aspects cliniques, diagnostiques et thérapeutiques de cette pathologie.Observation : Nous rapportons un cas de FCC apparue dans les suites d’un traumatisme craniofacial et survenue chez un homme de 25 ans ayant été victime d’un accident de la voie publique. Le diagnostic a été suspecté devant l’apparition, au 19ème jour d’hospitalisation, d’une exophtalmie unilatérale gauche pulsatile associée à un important chémosis et à une pupille aréflectique. Une artériographie cérébrale pratiquée 9 jours après la constatation de l’exophtalmie a objectivé une large FCC gauche. Une embolisation au moyen de deux ballonnets intravasculaires largables et de l’injection de colle biologique a été réalisée au même temps sans incidents permettant d’obtenir l’occlusion complète de la fistule. L’évolution a été marquée par la régression de l’exophtalmie et du chémosis et par l’amélioration partielle de l’acuité visuelle.Conclusion : Le traitement des FCC est urgent et est principalement basé sur la neuroradiologie interventionnelle. en effet, l’angiographie cérébrale constitue l’examen clé et possède un double intérêt diagnostique et thérapeutique.Mots clés : fistule carotido-caverneuse, traumatisme craniofacial, artériographie cérébrale, embolisation