401 resultados para Brake Fade.
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National Highway Traffic Safety Administration, Washington, D.C.
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National Highway Traffic Safety Administration, Office of Research and Development, Washington, D.C.
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Mode of access: Internet.
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Mode of access: Internet.
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Final report; December 1977.
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Mode of access: Internet.
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Hearings held Dec. 6, 1977-
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A number of commercial Al-Sr master alloys of differing Sr content and product form have been added to Al-7Si-0.5Mg casting alloy melts and held at constant temperature for periods up to 7 hours following the addition. The master alloys were added to achieve a specific Sr target level of 200 ppm, and the melts were held at various temperatures (most at 710ºC, but also 670, 690, 740 and 770ºC). A total of thirty six melt trials were conducted and during each trial chill-cast disc samples were taken throughout for subsequent chemical analysis. The Sr concentration versus time data of each trial has been considered in terms of Sr dissolution/recovery behaviour, as well as Sr loss/fade. Trends in the data are identified and discussed, and implications for industrial practices are suggested.
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This study is primarily concerned with the problem of break-squeal in disc brakes, using moulded organic disc pads. Moulded organic friction materials are complex composites and due to this complexity it was thought that they are unlikely to be of uniform composition. Variation in composition would under certain conditions of the braking system, cause slight changes in its vibrational characteristics thus causing resonance in the high audio-frequency range. Dynamic mechanical propertes appear the most likely parameters to be related to a given composition's tendency to promote squeal. Since it was necessary to test under service conditions a review was made of all the available commercial test instruments but as none were suitable it was necessary to design and develop a new instrument. The final instrument design, based on longitudinal resonance, enabled modulus and damping to be determined over a wide range of temperatures and frequencies. This apparatus has commercial value since it is not restricted to friction material testing. Both used and unused pads were tested and although the cause of brake squeal was not definitely established, the results enabled formulation of a tentative theory of the possible conditions for brake squeal. The presence of a temperature of minimum damping was indicated which may be of use to braking design engineers. Some auxilIary testing was also performed to establish the effect of water, oil and brake fluid and also to determine the effect of the various components of friction materials.
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There is an increasing call for applications which use a mixture of batteries. These hybrid battery solutions may contain different battery types for example; using second life ex-transportation batteries in grid support applications or a combination of high power, low energy and low power, high energy batteries to meet multiple energy requirements or even the same battery types but under different states of health for example, being able to hot swap out a battery when it has failed in an application without changing all the batteries and ending up with batteries with different performances, capacities and impedances. These types of applications typically use multi-modular converters to allow hot swapping to take place without affecting the overall performance of the system. A key element of the control is how the different battery performance characteristics may be taken into account and the how the power is then shared among the different batteries in line with their performance. This paper proposes a control strategy which allows the power in the batteries to be effectively distributed even under capacity fade conditions using adaptive power sharing strategy. This strategy is then validated against a system of three different battery types connected to a multi-modular converter both with and without capacity fade mechanisms in place.
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Az Európai Unió megújuló gazdasági kormányzási rendszerének egyik meghatározó pillére a diszkrecionális gazdaságpolitikával szemben megfogalmazott szabályalapúság lesz. A minden korábbinál erősebb és vélhetően hatékonyabb szabályok bevezetésének legelkötelezettebb híve Németország. Az elmúlt évtizedekben a folyó költségvetési kiadások hiányból történő finanszírozásának tilalmát előíró aranyszabályt inkább kevesebb, mint több sikerrel alkalmazó Németország most arra vállalkozott, hogy nem csak saját hatáskörben vezeti be az ún. adósságféket, hanem követendő példaként állítja azt a többi tagország elé is. Írásunkban az aranyszabály, illetve az adósságfék előnyeit és hátrányait vesszük számba a német tapasztalatok felhasználásával. / === / The need to strengthen rules-based fiscal policy has emerged as a widely shared consensus amongst policy-makers in the recent economic and financial crisis. Germany has become the most devoted advocator of the new regime, where more innovative and effective fiscal rules are supposed to play an even bigger role than before. Germany supports such a move however not only in rhetoric but also in practice. It decided to abandon its several decade old golden rule and to adopt a more sophisticated one, the so-called debt-brake. This article provides a cost-benefit analysis of both the previous and the new fiscal rule.
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A bicycle ergometer is a scientific device used by exercise physiologists which attempts to mimic on-road cycling characteristics such as foot technique, EMG activity, VO2, VCO2 and rider cardiology in a laboratory environment. Presently there are no known useful scientific ergometers that mimic these characteristics and are able to provide a satisfactory controlled resistance that is independent of speed. Previous research has suggested the use of a Magneto-Rheological (MR) Fluid as part of the ergometer design, as when used in a rotary brake application it is able to be controlled electronically to increase resistance instantly and independent of speed. In the target application, MR fluids are subject to immense tribological wear and temperature during viscous shearing, and will eventually show some degree of deterioration which is usually manifested as an increase in off-state viscosity. It is not known exactly how the fluid fails, however the amount of deterioration is related to the shear rate, temperature and duration and directly related to the power dissipation. Currently, there is very little literature that investigates the flow and thermal characteristics of MR fluid tribology using CFD. In this paper, we present initial work that aims to improve understanding of MR fluid wear via CFD modelling using Fluent, and results from the model are compared with those obtained from a experimental test rig of an MR fluid-based bicycle ergometer.