A numerical control algorithm for a B-double truck-trailer with steerable trailer wheels and active hitch angles. Part 2: reversing

The authors have previously proposed a solution to the twin problems of wheel scuffing and off-tracking of B-double truck–trailer vehicles thereby reducing tyre wear and environmental damage as well as improving maneuverability. The solution to the scuffing problem requires that trailer axles in excess of one per trailer must have steerable wheels. However, if all trailer wheels are steerable, then the off-tracking problem can also be solved. The previous work devised an algorithm for a B-double in forward motion, whereby an on-board computer would be used to calculate the correct wheel and hitch angles and a control system would implement these angles. The purpose of the present technical note is to complete the study of a numerical algorithm for navigating a B-double truck–trailer vehicle by considering travel in the reverse direction. In this case the angle of the front wheels of the truck must also be controlled by the on-board computer. The algorithm for determining the effective angle of the truck’s steerable wheels is derived using an innovative combination of vector geometry and calculus and completes the total control system for these B-double vehicles. The paper concludes with a simulation study of the control algorithm demonstrating its versatility for reversing along twisting paths and effectiveness in reducing off-tracking

Trailer Sway Control Using an Active Hitch

The handling and yaw stability characteristics of passenger vehicles are drastically changed when towing a trailer, which can lead to unsafe oscillations in the trailer yaw, known as trailer sway. This thesis examines the feasibility of using lateral articulation of the hitch ball to reduce sway behavior in passenger-sized tractor-trailer configurations. An articulating hitch ball design has the advantage of not being dependent on the trailer being towed, providing stability improvements to the wide variety of trailers that a passenger vehicle may tow over its life cycle. Changes in the lateral position of the hitch relative to the tractor create dynamic changes to the heading angle of the trailer relative to the tractor, which act as compensating steering inputs into the system. To examine the effectiveness of this method, a linear handling model was developed to predict the system response with different trailer configurations and feedback methods. This model was simulated with various feedback controllers, and the modeling was validated using a model constructed in MapleSim, a high-fidelity multibody simulation tool. After establishing the required performance characteristics of the active hitch, a prototype was designed, manufactured, and tested in a full scale tractor-trailer combination. The modeling techniques showed good agreement with the physical testing, where the control design of proportional feedback on the trailer articulation angle provided improved yaw stability across many trailer configurations. The simple controller design is adaptable to driving conditions and requires minimal measurements of vehicle states. The performance of the active hitch prototype is best shown in a response to a steering impulse at 65km/h, where a highly unstable trailer causes steady state oscillation without control, and settles in under 4 seconds with control active

Trailer Sway Control Using an Active Hitch

The handling and yaw stability characteristics of passenger vehicles are drastically changed when towing a trailer, which can lead to unsafe oscillations in the trailer yaw, known as trailer sway. This thesis examines the feasibility of using lateral articulation of the hitch ball to reduce sway behavior in passenger-sized tractor-trailer configurations. An articulating hitch ball design has the advantage of not being dependent on the trailer being towed, providing stability improvements to the wide variety of trailers that a passenger vehicle may tow over its life cycle. Changes in the lateral position of the hitch relative to the tractor create dynamic changes to the heading angle of the trailer relative to the tractor, which act as compensating steering inputs into the system. To examine the effectiveness of this method, a linear handling model was developed to predict the system response with different trailer configurations and feedback methods. This model was simulated with various feedback controllers, and the modeling was validated using a model constructed in MapleSim, a high-fidelity multibody simulation tool. After establishing the required performance characteristics of the active hitch, a prototype was designed, manufactured, and tested in a full scale tractor-trailer combination. The modeling techniques showed good agreement with the physical testing, where the control design of proportional feedback on the trailer articulation angle provided improved yaw stability across many trailer configurations. The simple controller design is adaptable to driving conditions and requires minimal measurements of vehicle states. The performance of the active hitch prototype is best shown in a response to a steering impulse at 65km/h, where a highly unstable trailer causes steady state oscillation without control, and settles in under 4 seconds with control active

Proceedings of the 8th Annual Summer Conference: NASA/USRA Advanced Design Program

Papers presented at the 8th Annual Summer Conference are categorized as Space Projects and Aeronautics projects. Topics covered include: Systematic Propulsion Optimization Tools (SPOT), Assured Crew Return Vehicle Post Landing Configuration Design and Test, Autonomous Support for Microorganism Research in Space, Bioregenerative System Components for Microgravity, The Extended Mission Rover (EMR), Planetary Surface Exploration MESUR/Autonomous Lunar Rover, Automation of Closed Environments in Space for Human Comfort and Safety, Walking Robot Design, Extraterrestrial Surface Propulsion Systems, The Design of Four Hypersonic Reconnaissance Aircraft, Design of a Refueling Tanker Delivering Liquid Hydrogen, The Design of a Long-Range Megatransport Aircraft, and Solar Powered Multipurpose Remotely Powered Aircraft

The Art of Movies

Movie is considered to be an important art form; films entertain, educate, enlighten and inspire audiences. Film is a term that encompasses motion pictures as individual projects, as well as — in metonymy — the field in general. The origin of the name comes from the fact that photographic film (also called filmstock) has historically been the primary medium for recording and displaying motion pictures. Many other terms exist — motion pictures (or just pictures or “picture”), the silver screen, photoplays, the cinema, picture shows, flicks — and commonly movies

2015, UMaine News Press Releases

This is a catalog of press releases put out by the University of Maine Division of Marketing and Communications between January 2, 2015 and December 31, 2015

Nuyoricans

Die Dissertation ist ein Beitrag zur Debatte um die Revision des amerikanistischen Lektürekanons. Ihre drei Schwerpunkte sind die Geschichte und Mythologie der Karibikinsel Puerto Rico, die soziale Lage und das Image der Puertoricaner in den USA sowie die auf Englisch erschienene Erzählliteratur von Autoren puertoricanischer Herkunft. (1) Die spanische Kolonie Puerto Rico kam 1898 in den Besitz der USA und erlebte in der zweiten Hälfte des 20. Jahrhunderts einen rasanten ökonomischen Aufstieg, der mit wachsender Abhängigkeit vom amerikanischen Wohlfahrtsstaat erkauft ist. In freien Referenden bejahte jeweils eine knappe Mehrheit den Zwitterstatus ihrer Insel, die bis heute weder ein Staat der USA noch ein souveränes Land ist. Da jedoch der Kongress in Washington über die Zukunft des Commonwealth of Puerto Rico zu bestimmen hat, bleibt die Insel eine Kolonie der USA. Puerto Ricos Mythologie ist von Stereotypen geprägt, die sich zu einem negativen Klischee vom Nationalcharakter des Landes verdichtet haben. Die amerikanische Dominanz in Politik, Wirtschaft und Kultur verstärkt die von vielen beklagte Schizophrenie Puerto Ricos. Die Chance einer Lösung des puertoricanischen Syndroms verspricht nur die nationale Unabhängigkeit. (2) Stereotype bestimmen auch das Bild von den übergesiedelten Puertoricanern, den Nuyoricans, in der Öffentlichkeit der USA. Das Negativimage der kaum assimilierten Gruppe wird von den Massenmedien verfestigt, obwohl seriöse Studien zeigen, dass frühere Immigranten ähnliche Probleme mit sich brachten. Die Mehrheit der US-Experten propagiert nach wie vor die allmähliche Assimilation der Übersiedler im Rahmen eines kulturellen Pluralismus. Bei den Puertoricanern geht der Trend seit dem Aufkommen des Multikulturalismus in Richtung einer hybriden, bikulturellen Identität, in ein Wort gefasst mit dem Begriff Nuyorican. Die Dissertation bietet eine Auswertung der auf Englisch erschienenen Literatur über die Puertoricaner in den USA unter 15 Aspekten: Kultur, Religion, Bildung, Sprache, Politik, Arbeit, welfare, Wohnverhältnisse, ethnicity, race, class, gender, Familie, Law and order und Migration. Am Beispiel von belletristischen Texten, Spielfilmen und Musicals wird gezeigt, dass die Puertoricaner in diesen Genres größtenteils wohlwollend dargestellt erscheinen. Das gilt auch für das Musical West Side Story, dem viele Kritiker zu Unrecht vorwerfen, die puertoricanischen Jugendlichen als Gangster zu stigmatisieren. (3) Die puertoricanische Prosa in englischer Sprache hat im Kanon der amerikanischen Literatur und in der Kritik bisher kaum eine Rolle gespielt. Vor allem die zahlreichen Neuerscheinungen der achtziger und neunziger Jahre werden hier erstmals auf historisch-soziologischer Basis analysiert. Allgemeine Trends der neueren Nuyorican-Literatur sind ihre Diversifizierung und Feminisierung. Größere Vielfalt gibt es heute bei den Schauplätzen, den Textsorten und den Themen. Das Thema gender steht nicht nur bei den Frauen, sondern auch bei männlichen Autoren oft im Mittelpunkt. Von den Autoren, die New York zum Schauplatz gewählt haben, ist Abraham Rodriguez, Jr. der bedeutendste. Rodriguez erzählt von Teenagern in der South Bronx, deren puertoricanische Ethnizität kein bestimmender Faktor mehr ist. So ist er der am weitesten amerikanisierte Autor der Nuyoricans. Die überzeugendste Interpretation des Migrationsprozesses bietet Esmeralda Santiago. Bei ihr steht die Kritik am traditionellen puertoricanischen Sexismus im Zentrum. Eine feministische Grundtendenz haben auch die in Puerto Rico angesiedelten, zum Teil magisch-realistischen Werke von Rosario Ferré. Die besten Werke von Rodriguez, Santiago, Ferré und weiteren Puertoricanern verdienen Anerkennung als wertvoller und zukunftweisender Beitrag zur amerikanischen Literatur.The thesis contributes to the debate about the revision of the American literary canon. Its first focus is on the history and mythology of Puerto Rico, the second on the social situation and image of the Puerto Ricans in the U.S., and the third on the prose literature by authors of Puerto Rican descent published in English. (1) The Spanish colony of Puerto Rico became a possession of the U.S. in 1898 and experienced a rapid economic rise in the second half of the 20th century, at the expence of growing dependence on the American welfare state. In free referendums the people of Puerto Rico have so far condoned the intermediate status of their island, which still is neither a state of the union nor an independent nation. But in fact the Commonwealth of Puerto Rico remains a colony of the U.S., as the real power to decide about its status lies with Congress. Puerto Rico's mythology has from the start been dominated by stereotypes, which have resulted in a negative cliché of its national character. The United States' political, economic and cultural hegemony has reinforced the alleged schizophrenic state of Puerto Rico. The only chance of healing this Puerto Rican syndrome is the island's national independence. (2) Stereotypes have also determined the image in the American public of the Puerto Ricans who have migrated to the mainland. The bad reputation of this hardly assimilated group is constantly being confirmed by the mass media, although serious studies prove that earlier immigrants had similar problems. Most U.S. experts still advocate the migrants' gradual assimilitation according to the ideal of cultural pluralism. Since the rise of multiculturalism, within the U.S. Puerto Rican community the trend has been going towards a hybrid, bicultural, Nuyorican identity. The dissertation assesses the literature about Puerto Ricans in the U.S. published in English from 15 key aspects: culture, religion, education, language, politics, work, welfare, housing, ethnicity, race, class, gender, family, law and order und migration. A critical look at books, movies and musicals by non-Puerto Ricans shows that in these genres migrants from Puerto Rico have by and large been portrayed benevolenty. This is true even for the musical West Side Story, which has often been wrongly blamed for stigmatizing Puerto Rican youngsters as gangsters. (3) Puerto Rican prose literature in English has so far played little role in the American canon and in criticism. This thesis offers the first analysis of the many new volumes from the eighties and nineties on a socio-historical basis. The overall trends of recent Nuyorican literature are its diversification und feminization. There is a greater diversity of settings, text types and themes. Gender is a central issue not only with the women, but also with a number of male authors. Of those writers who take New York as the setting, Abraham Rodriguez, Jr. is the most important. Rodriguez's books are about teenagers in the South Bronx whose Puerto Rican ethnicity is no crucial factor any more. Thus he is the most Americanised author among the Nuyoricans. The most convincing interpretation of the migratory process is Esmeralda Santiago's. Her main thrust is against the Puerto Rican tradition of sexism. The works of Rosario Ferré, some told in magic realism and all set in Puerto Rico, also have a feminist tendency. The best books by Rodriguez, Santiago, Ferré and a few more Puerto Ricans deserve to be recognised as a valuable and visionary contribution to American literature