204,252 research outputs found
Dynamic simulation of a roller rig
No full textThe dynamic behaviour of railway vehicles is greatly influenced by the interaction of the wheelsets on the railway track. This behaviour can be replicated in laboratory conditions using a scaled roller rig. This paper presents the results of the modeling and simulation of a one-fifth scale roller rig. The simulation results obtained have been compared with a real railway vehicle (bogie) on the track. It has been observed that the scale roller rig has a much lower critical velocity than real railway vehicle due to the similarity and dimensional scaling laws that are taken into consideration in the roller rig design. The scale roller rig critical speed was observed to be 10.2 m/s while the Full Scale railway vehicle model was found to be 52 m/s. It can be concluded that the critical speed of the scaled roller rig model is one-fifth of the full scale critical speed
The Unladylike Ladies of Roller Derby?: How Spectators, Players and Derby Wives Do and Redo Gender and Heteronormativity in All-Female Roller Derby
No full textAll-female roller derby is a rapidly growing full-contact sport played on quad roller skates, with a highly popularized punk, feminine, sexual and tough aesthetic. Utilising theories on the institution of heterosexuality, I conducted a qualitative study on all-female roller derby which evaluated the way in which derby aligns with or challenges heteronormativity. In order to approach this question, I analysed, firstly, thirty-eight interviews with spectators, and twelve with players about their interactions with spectators. Secondly, I interviewed twenty-six players about the phenomenon of “derby wives,” a term used to describe particular female friendships in roller derby. My findings relate the complex relationship between players and spectators by focusing on: (i) spectators’ interpretations of the dress, pseudonyms, and identities of players, as well as the ways in which they were actively involved in doing gender through their discussions of all-female, coed, and all-male roller derby; (ii) players’ descriptions of their interactions with spectators, family members, romantic partners, friends and strangers, regarding roller derby. Additionally, I address the reformulation of the role “wife” to meet the needs of female players within the community, and “derby wives” as an example of Adrienne Rich’s (1980) “lesbian continuum.” “Derby girls” are described as “super heroes” and “rock stars.” Their pseudonyms are believed to help them “transform” once they take to the track. Roller derby is seen as providing a venue to showcase women’s strength and new conceptualizations of femininity and motherhood. However, my findings also indicate that with its many challenges to gender stereotypes, heterosexuality and gender dualism are pervasive and evident in the sport. Even though derby has done much to expand gender expectations, these expectations have only been expanded; they are not diminished or eradicated. Despite this, through all-female roller derby, women are seen as acting in new, transformative ways
Modelling and simulation of dynamic wheel-rail interaction using a roller rig
No full textThe interaction between the wheel and rail greatly influences the dynamic response
of railway vehicles on the track. A roller rig facility can be used to study and monitor real time parameters that influence wheel-rail interaction such as wear, adhesion, friction and
corrugation without actual field tests being carried out. This paper presents the development of the mathematical models for full scale roller rig and 1/5 scale roller rig and the wear prediction model based on KTH wear function. The simulated critical speed for the 1/5 scale roller rig is about one-fifth of the critical speed for the full scale model so the simulated results compare well with the theory related to wheel-rail contact and dynamics. Also the differences between the simulated rolling radii for the full scale model with and without wear function are analysed. This paper presents the initial stage of a large scale research project where the influence of wear on the wheel-rail performance will be studied in more depth
Power Packer Sheepsfoot Roller Model M-50, Lt8 16884
No full textPhotograph of the Power Packer Sheepsfoot Roller Model M-50. LeTourneau introduced its first diesel-electric, self-powered sheepsfoot roller in March 1959, according to author Eric Orlemann
Sheepsfoot Roller Pacemaker Series M-50-55, Lt8 17617
No full textPhotograph of Sheepsfoot Roller Pacemaker Series M-50-55, built in August 1967. A total of 31 of these units were built, according to author Eric Orlemann
Analysis of Material Deformation and Wrinkling Failure in Conventional Metal Spinning Process
No full textSheet metal spinning is one of the metal forming processes, where a flat metal blank is rotated at a high speed and formed into an axisymmetric part by a roller which gradually forces the blank onto a mandrel, bearing the final shape of the spun part. Over the last few decades, sheet metal spinning has developed significantly and spun products have been widely used in various industries. Although the spinning process has already been known for centuries, the process design still highly relies on experienced spinners using trial-and-error. Challenges remain to achieve high product dimensional accuracy and prevent material failures. This PhD project aims to gain insight into the material deformation and wrinkling failure mechanics in the conventional spinning process by employing experimental and numerical methods. In this study, a tool compensation technique has been proposed and used to develop CNC multiple roller path (passes). 3-D elastic-plastic Finite Element (FE) models have been developed to analyse the material deformation and wrinkling failure of the spinning process. By combining these two techniques in the process design, the time and materials wasted by using the trial-and-error could be decreased significantly. In addition, it may provide a practical approach of standardised operation for the spinning industry and thus improve the product quality, process repeatability and production efficiency. Furthermore, effects of process parameters, e.g. roller path profiles, feed rate and spindle speed, on the variations of tool forces, stresses, strains, wall thickness and wrinkling failures have also been investigated. Using a concave roller path produces high tool forces, stresses and reduction of wall thickness. Conversely, low tool forces, stresses and wall thinning have been obtained in the FE model which uses the convex roller path. High feed ratios help to maintain original blank thickness but also lead to material failures and rough surface finish. Thus it is necessary to find a “trade off” feed ratio for a spinning process design
A novel mechatronic running gear: concept, simulation and scaled roller rig testing
No full textThe basic idea of the concept of the novel mechatronic running gear consists of independently rotating wheels with a mechatronic guidance system to overcome the disadvantages which conventional wheelsets show under certain operating conditions. Especially in narrow curves or at very high speed, oscillation problems linked with noise and increased wear can be observed at conventional wheelsets (curve squeal, hunting instability). Otherwise, vehicles with independently rotating wheels often need a higher maintenance effort to ensure low wear at the wheels.
The aim of the concept is the development of a running gear which offers a better running performance than a conventional running gear under all operation conditions in combination with a low maintenance effort. This means a lower emission level of vibrations to the ground and the air as well as less friction at curves and therefore a lower need for traction energy.
Additionally, the running gear concept enables more comfortable train concepts such as low floor trams or double deck trains with two continuous decks, because of the abdication of the wheelset axle. The principle is applicable to bogies as well as running gears with a single pair of wheels.
These ambitious aims require high demands of the sensor and control system. For instance, the sensor must be able to identify the position of the wheels relative to the track and the control system must be fast enough to avoid flange contact even at highly disturbed tracks at high speed.
In the first step a scaled 1:5 roller rig is build (picture) and a model of the scaled roller rig is set up as Multi-Body-System (MBS). In the roller rig force-torque-sensors are used as position sensors. The model can be validated by measurements at the test rig. Then the validated model is used for the design process of the control-algorithms which are tested in the roller rig. Only a model-based control system is able to meet the high demands under the different operation conditions of a train.
In a second step the developed control algorithms are transferred into a MBS-model of a 1:1 vehicle to demonstrate the functional capability and the advantages of the simulated operation conditions.
Currently this work has the function of a demonstrator and to identify the further research emphasis for an implementation in a real vehicle concept.
At the end this novel mechatronic running gear will increase the competitiveness and acceptance of the railway by a cost-effective and low emission running gear.
This work is integrated in the DLR-Project Next Generation Train
Sojourners to Another Country: The Psychological Roller-Coaster of Cultural Transitions
No full textCultural sojourners are temporary visitors to another country who return to their home country. They can be students enrolled in a foreign university or corporate employees assigned to an international branch of their company. This chapter explores the psychological aspects of the cultural transition cycle experienced by the sojourner. The concepts of enculturation and cultural identity are introduced followed by a discussion of a transition model which focuses on awareness, adjustment, adaptation, self-concept change, cultural identity response and repatriation. Ideas for minimizing repatriation distress are suggested
Archeologisch bureau- en booronderzoek ter plaatse van Winsumerweg 1 te Groningen, gemeente Groningen (GR)
No full textAlleen in het zuiden en zuidwesten is een bodemlaag met mogelijke archeologische waarden aanwezig, de vegetatiehorizonten. De bodemingreep voor de nieuwbouw is 80 cm-mv. De aanwezige vegetatiehorizonten liggen op circa 1 m-mv. Bodem- ingrepen voor de nieuwbouw dienen ter hoogte van boringen 1 en 2 niet dieper te zijn dan 0,9 m-mv. De bodem-ingreep voor de nieuwbouw zal daardoor de vegetatiehorizonten niet verstoren
Archeologisch bureau- en booronderzoek met aanvullende boringen aan Van Houtenlaan 27 te Groningen, gemeente Groningen (GR)
No full textUit het booronderzoek blijkt dat binnen het grootste deel van het onderzoeksgebied een esdek aanwezig is (boringen 1 t/m 3, 01A, 02A en 6). Vanwege de aanwezigheid van een esdek moet rekening gehouden worden met mogelijke archeologische resten uit de periode steentijd- middeleeuwen-nieuwe tijd.
De bovenste meter van de bodem is opgebracht en bevat in een aantal boringen rond de 1 m-mv puin. Dit puin is mogelijk afkomstig van de bouw van de flat dat aan het eind van de jaren ’50 van de vorige eeuw heeft plaats gevonden. Er kan niet worden uitgesloten dat een deel van het puin ook van de bebouwing afkomstig is die hier in de 19e eeuw heeft gestaan
- …
