Limit Cycle Prediction of Systems with Fractional Controllers and Backlash

This article investigates the limit cycle (LC) prediction of systems with backlash by means of the describing function (DF) when using discrete fractional-order (FO) algorithms. The DF is an approximate method that gives good estimates of LCs. The implementation of FO controllers requires the use of rational approximations, but such realizations produce distinct dynamic types of behavior. This study analyzes the accuracy in the prediction of LCs, namely their amplitude and frequency, when using several different algorithms. To illustrate this problem we use FO-PID algorithms in the control of systems with backlash.

Life Cycle Assessment of the Hybrid Vehicle ��� Toyota Prius

Die Luftverschmutzung, die globale Erw��rmung sowie die Verknappung der endlichen Ressourcen sind die gr����ten Bedenken der vergangenen Jahrzehnte. Die Nachfrage nach jeglicher Mobilit��t steigt rapide. Dementsprechend bem��ht ist die Automobilindustrie L��sungen f��r Mobilit��t unter dem Aspekt der Nachhaltigkeit und dem Umweltschutz anzubieten. Die Elektrifizierung hat sich hierbei als der beste Weg herausgestellt, um die Umweltprobleme sowie die Abh��ngigkeit von fossilen Brennstoffen zu l��sen. Diese Arbeit soll einen Einblick ��ber die Umweltauswirkungen des Hybridfahrzeuges Toyota Prius geben. Hierbei findet eine Gliederung in vier verschiedene Lebensphasen statt. Im Anschluss bietet die Sachbilanz die M��glichkeit die Umweltauswirkungen mit verschiedenen Antriebsm��glichkeiten und Brennstoffen zu vergleichen. Das Modell hat gezeigt, dass der Toyota Prius w��hrend der Nutzung einen hohen Einfluss auf das Treibhauspotenzial aufweist. Durch die Nutzung anderer Brennstoffe, wie beispielsweise Ethanol oder Methanol lassen sich die Auswirkungen am Treibhauspotenzial sowie der Verbrauch an abiotischen Ressourcen reduzieren. Vergleicht man die Elektromobilit��t mit der konventionellen, so ist festzustellen, dass diese Art der Mobilit��t die derzeit beste M��glichkeit zur Reduzierung der Umweltbelastungen bietet. Die Auswirkungen der Elektromobilit��t sind im hohen Ma��e abh��ngig von der Art des verwendeten Strommixes.

The influence of gait cadence on the ground reaction forces and plantar pressures during load carriage of young adults

Biomechanical gait parameters���ground reaction forces (GRFs) and plantar pressures���during load carriage of young adults were compared at a low gait cadence and a high gait cadence. Differences between load carriage and normal walking during both gait cadences were also assessed. A force plate and an in-shoe plantar pressure system were used to assess 60 adults while they were walking either normally (unloaded condition) or wearing a backpack (loaded condition) at low (70 steps per minute) and high gait cadences (120 steps per minute). GRF and plantar pressure peaks were scaled to body weight (or body weight plus backpack weight). With medium to high effect sizes we found greater anterior-posterior and vertical GRFs and greater plantar pressure peaks in the rearfoot, forefoot and hallux when the participants walked carrying a backpack at high gait cadences compared to walking at low gait cadences. Differences between loaded and unloaded conditions in both gait cadences were also observed.

Integration of the project team in the classic maintenance cycle

A manuten����o �� uma ��rea extremamente importante, principalmente na ind��stria. Devidamente organizada, permitir�� um fluxo produtivo devidamente planeado e executado, que permitir�� a qualquer empresa manter o n��vel de factura����o desejado e o prazo de entrega acordado com os clientes. De outra forma, poder�� originar o caos. No entanto, os desafios de gest��o da produ����o mais correntes, nomeadamente atrav��s do Lean Manufacturing, passam a exigir um pouco mais do que uma simples manuten����o. Torna-se obrigat��rio fazer an��lises econ��micas que permitam averiguar quando cada equipamento passa a exigir custos de manuten����o excessivos, os quais poder��o obrigar a um recondicionamento mais acentuado do equipamento, o qual pode passar inclusivamente por uma melhoria da sua performance. Nestes casos, ter�� que existir uma ���cumplicidade��� entre a Direc����o de Produ����o e a Manuten����o, no sentido de averiguar o melhor momento para proceder a uma melhoria do equipamento, numa perspectiva de funcionamento global em linha de produ����o, adaptando-o �� performance que ser�� exigida ao conjunto. Neste dom��nio, o Projecto passa a prestar um servi��o valios��ssimo �� empresa, integrando-se no conjunto Produ����o + Manuten����o, criando valor na interven����o, atrav��s do desenvolvimento de um trabalho que permite n��o s�� repor o estado natural da produ����o, mas sim promover uma melhoria sustentada da mesma. Este trabalho pretende reflectir e avaliar a relev��ncia do Projecto neste tipo de opera����es, contribuindo de uma forma sistem��tica e sustentada para a melhoria cont��nua dos processos de fabrico. �� apresentado um caso de estudo que pretende validar todo o desenvolvimento anteriormente realizado na mat��ria.