Higher-speed rail

Résumé

Higher-speed rail (HrSR), also known as high-performance rail, higher-performance rail, semi-high-speed rail or almost-high-speed rail, is the jargon used to describe inter-city passenger rail services that have top speeds of more than conventional rail but are not high enough to be called high-speed rail services. The term is also used by planners to identify the incremental rail improvements to increase train speeds and reduce travel time as alternatives to larger efforts to create or expand the high-speed rail networks. Though the definition of higher-speed rail varies from country to country, most countries refer to rail services operating at speeds up to . The concept is usually viewed as stemming from efforts to upgrade a legacy railway line to high speed railway standards (speeds in excess of ), but usually falling short on the intended speeds. The faster speeds are achieved through various means including new rolling stock such as tilting

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https://en.wikipedia.org/wiki/Higher-speed_rail

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The Emancipation of Destruction – Transforming Gällivare (Suède)

Linus Godet

Gällivare is a remote city in the middle of the northern Swedish wilderness. The city was established as iron ore was found in the ground just over a century ago. Until the 60's the mining industry and the city grew together in what seemed to be a perfect symbiosis. But as times changed and the industry had to adapt to a globalized market and bigger production volumes, the symbiosis was broken. The mines started expanding at a much higher speed, and the same industry that once founded the city is now threatening its whole existence. The last decades have been a story of destruction and relocations. The problems of dealing with destruction and relocating people have overshadowed the needs for visions and dreams. Experts from all over the world have gathered to solve the situation. The first step will be to build a knowledge center for cities in movement. Gällivare offers a very rare context. Most of the moving cities of the world are moved within a short period of time, while Gällivare is moving step by step every year. Many moving cities are actually disappearing as the inhabitants are forced to move, which makes documentation and research very difficult. Gällivare offers the opportunity to take part of the whole process, from planning to relocation. The knowledge center is the starting point for the visionary work of transforming Gällivare.

2009

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Initially, linear motors have been particularly dedicated to transportation systems. Nowadays, linear motors are meant to replace a system using a rotating motor and a transmission to realize a linear movement. With linear motors the performances increase considerably since the mechanical limitations are removed. This leads to a better precision, a higher acceleration and a higher speed of the moving part. Therefore, direct drives with linear motors are increasingly used in industrial applications although these solutions need often more investment costs. Different linear motor structures and technologies exist. They can be either induction or synchronous motors with a transverse or a longitudinal flux. Furthermore, linear motors may have several topologies. They can be either long or short stator and double or single sided. All these variants may be combined giving therefore numerous possibilities to perform a linear movement. Hence, to make the best choice for a given application, a global methodology based on the comparison of optimized motors is presented in the thesis. This design methodology is based on figure of merits which are bound to the specifications of the studied application. This method differs from a conventional one since optimized motors with the same objective function are compared. The optimized motors are obtained by an indirect method based on an optimization algorithm (Sequential Quadratic Programming, SQP). An indirect approach differs from the conventional deterministic one for which at least one parameter must be fixed to obtain a motor pre design, since there are constraints and validity domain which are introduced. The proposed methodology can be applied either to rotating or to linear motor design. The use of an optimization program to perform motor designs requires analytical motor models. The models developed in this thesis take into account the thermal behavior of the motors in order to achieve more realistic results. Furthermore, the analytical models of synchronous motors are thoroughly studied leading to several interesting conclusions. They are based on well known algorithms developed for rotating motors. The proposed models are very accurate in comparison with the FEM program, except for a transversal flux linear motor for which the obtained results are not worthwhile enough to be optimized. This is caused by the structure of the motor which is close to a reluctant motor and imposes to model the motor by a lumped magnetic scheme. Moreover, a global analysis of the windings due to the particularity of linear motor to have an even or odd number of poles is presented in the thesis. The methodology proposed in the thesis is successfully used for an innovative application which deals with a multi mobile system for a lift. For this lift, several cabins travel in the same shaft implying linear motors to move autonomously each cabin. First, by comparing the different motor technologies, the best motor type is selected. Afterwards, the motor windings for the selected motors are analyzed and compared in order to find the most adapted one for this application. The motor is finally optimized, leading to a motor design proposal. This motor design takes into account the thermal behavior, the material cost and the electrical characteristic of the linear motor.

EPFL2006

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Enhancement of actuation ability of ionic-type conducting polymer actuators using metal ion implantation

Herbert Shea

In this study, we present the results and implications of an experimental study into the effect of gold-ion implantation on the actuation performance of ionic-type conducting polymer actuators, represented here by cantilevered tri-layer polypyrrole (PPy) actuators. We implant gold ions beneath the outer surfaces of PPy-based conducting polymer layers of the actuators in order to increase the conductivity of these layers, and therefore improve the overall conductivity of the actuators. A Filtered Vacuum Cathode Arc (FVCA) ion source was used to implant gold particles into the conducting polymer layers. Electrode resistance and capacitance, surface resistance, current response, mechanical work output of the actuator samples were measured and/or calculated for the actuator samples with and without gold implantation in order to demonstrate the effect of the gold-implantation. The current passing through the conducting polymer electrodes during their ‘electrochemomechanical’ actuation was measured to determine the charging time constant of the actuators. The mechanical displacement output of the actuators was recorded. The results demonstrate that the conductivity of the actuators increases noticeably, which has a flow on effect on the current response (i.e., charge injected into the polymer layers) and the mechanical work output. While the gold implanted actuators had a higher mechanical stiffness therefore a smaller displacement output, their time constant is smaller, indicating a higher response speed. The gold-implanted actuators generated a 15% higher mechanical work output despite the adverse effects on the polymer of the vacuum processing needed for the ion implantation.

Elsevier2011

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EPFL2006