A lo largo de la historia, el hombre por su condición humana ha dependido de la movilidad para su subsistencia. Esta movilidad en particular el desplazamiento ha sido clave en el desarrollo evolutivo de las razas. Cada una de estas en los distintos periodos de tiempo han resuelto este movimiento de las maneras más variadas, tanto autónomamente como con la ayuda de sistemas mecánicos dando cuenta de una situación global de cultura y periodo histórico. Estos sistemas de desplazamiento no han sido excluyentes, sino que se han ido desarrollando paralelamente, abriendo posibilidades de variación y evolución de los mismos. Es aquí donde participa un factor importante y que será determinante en la elección del sistema; este factor es la distancia. Hoy en día cada sistema de desplazamiento está ligado al tramo que debe cubrir, y a la morfología de cada territorio, determinante físico de la trayectoria a desarrollarse entre dos puntos. A medida que las distancias aumentan, se incrementan también tiempos y costos en los desplazamientos. Caso particular de esta situación es nuestro país, donde la relación de distancias entre el largo y el ancho es extremadamente opuesta. Cubrir así una distancia de dos localidades ubicadas a lo ancho, difícilmente igualará la cobertura de otras dos ubicadas en dirección norte sur.

Recently, researchers have introduced the notion of super-peers to improve signaling efficiency as well as lookup performance of peer-to-peer (P2P) systems. In a separate development, recent works on applications of mobile ad hoc networks (MANET) have seen several proposals on utilizing mobile fleets such as city buses to deploy a mobile backbone infrastructure for communication and Internet access in a metropolitan environment. This paper further explores the possibility of deploying P2P applications such as content sharing and distributed computing, over this mobile backbone infrastructure. Specifically, we study how city buses may be deployed as a mobile system of super-peers. We discuss the main motivations behind our proposal, and outline in detail the design of a super-peer based structured P2P system using a fleet of city buses. / Singapore-MIT Alliance (SMA)

Digital computers have changed human society in a profound way over the last 50 years. Key properties that contribute to the success of the computer are flexible programmability and fast access to large amounts of data and instructions. Effective access to algorithms and data is a fundamental property that limits the capabilities of computer systems. For PC computers, the main memory consists of dynamic random access memory (DRAM). Communication between memory and processor has traditionally been performed over a multi-drop bus. Signal frequencies on these buses have gradually increased in order to keep up with the progress in integrated circuit data processing capabilities. Increased signal frequencies have exposed the inherent signal degradation effects of a multidrop bus structure. As of today, the main approach to tackle these effects has been to reduce the number of endpoints of the bus structure. Though improvements in DRAM memory technology have increased the available memory size at each endpoint, the increase has not been able to fully fulfill the demand for larger system memory capacity. Different bus structural changes have been used to overcome this problem. All are different compromises between access latency, data transmission capacity, memory capacity, and implementation costs. In this thesis we focus on using the signal processing capabilities of a modern integrated circuit technology as an alternative to bus structural changes. This has the potential to give low latency, high memory capacity, and relatively high data transmission capacity at an additional cost limited to integrated circuit blocks. We first use information theory to estimate the unexplored potential of existing multi-drop bus structures. Hereby showing that reduction of the number of endpoints for multi-drop buses, is by no means based on the fundamental limit of the data transmission capacity of the bus structure. Two test-chips have been designed and fabricated to experimentally demonstrate the feasibility of several Gb/s data-rates over multidrop buses, with limited cost overhead and no latency penalty. The test-chips implement decision feedback equalization, adopted for high speed multi-drop use. The equalizers feature digital filter implementations which, in combination with high speed DACs, enable the use of long digital filters for high speed decision feedback equalization. Blind adaptation has also been implemented to demonstrate extraction of channel characteristics during data transmission. The use of single sided equalization has been proposed in order to limit the need for equalization implementation to the host side of a DRAM memory bus. Furthermore, we propose to utilize the reciprocal properties of the communication channel to ensure that single sided equalization can be performed without any channel characterization hardware on the memory chips. Finally, issues related to evaluation of high-speed channels are addressed and the on-chip structures used for channel evaluation in this project are presented.

When driving a vehicle on the road, the driver has to compensate continuously for small directional deviations from the desired course due to disturbances such as crosswinds, road irregularities and unintended driver inputs. These types of deviations have a tiring effect on the driver and should therefore be minimised. When the magnitude of these disturbances increases, especially with crosswind, the directional deviation might become so large that the driver will have difficulties in compensating for it, and will thereby affect the traffic safety. The objective of this research work is to increase the understanding of the crosswind sensitivity of buses and to find solutions to the problem of improving the safety of buses with respect to crosswind performance. The work presented in this thesis contributes to increased knowledge about the directional stability of buses under the influence of crosswind gusts through parameter studies using detailed vehicle simulation models, through full-scale experiments and through studies of the effect of steering feel on the subjective and objective evaluation of crosswind performance. A natural crosswind gust model has been derived from wind tunnel measurements and implemented in a multi-body dynamics simulation tool. The aerodynamic loads of the crosswind gust model have been applied on a detailed vehicle model and the behaviour of the vehicle model has been studied for various vehicle configurations in both open- and closed-loop manoeuvres. The vehicle model, with parameters corresponding to real vehicle data, has been validated and the agreement with measurements is good. A method for estimating the aerodynamic loads on a bus due to crosswind on a road section is also presented. Aerodynamic loads under real conditions were estimated using this method and these data were thereafter used in a study where the effect of steering feel on the subjective and objective evaluation of crosswind performance was investigated using a moving-base driving simulator, with the aim of finding a relationship between steering feel and crosswind sensitivity. The thesis covers the influence of changing chassis-related parameters and aerodynamics-related parameters on the crosswind sensitivity, as well as the influence of the setting of the steering system on the crosswind performance of the driver-vehicle system. The results identify areas of high potential for improving the crosswind sensitivity of buses, such as the centre of gravity location and the yaw moment overshoot at gust entry. Furthermore, the study shows the importance of having a vehicle that facilitates prompt driver corrections for reducing the lateral deviation under crosswind excitation; i.e. it is shown that a steering system with the possibility of changing the yaw rate gradient referencing the steering-wheel input when the vehicle is subjected to a sudden crosswind has a good potential for improving the crosswind performance of the driver-vehicle system. / QC 20100722

There is no international regulation for the frontal collision of the buses, protecting their occupants and partners in traffic. There are some regulation such as ECE R-80 which deals with strength of seat structure of the coaches and their anchorages strength. There is increasing need to focus issues like occupant protection and full scale crash testing regulation for buses. This thesis attempts to collect possible subjects required for international regulation required for crashworthiness of transit buses. This research attempts to develop and validate a model of transit bus for all three impact conditions. The full finite element model is developed with help hypermesh software and its validation and analysis is done with help Ls-Dyna nonlinear finite element solver. The cost of actual testing and secrecy maintained by manufacturers make research process difficult and increase the importance of computer simulations. To boost the research of crash worthiness of transit need for computer model is felt. This thesis examines several frontal crash test procedures and evaluates how well each procedure meets the objective. This validated model is used to analyze various real world impact scenarios and its analysis with European and federal regulation. This validated model is used to extract crash pulses of various impact scenarios at the center of gravity of the bus. These extracted crash pulses are applied to the madymo model to estimate the injuries to occupants of the bus. This thesis discusses the design aspects of bus frontal impact behavior as one of the main subjects of bus crashworthiness and results of previous full scale tests comparing the Fem simulation results carried out on the transit bus. / Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering / "December 2006."

published_or_final_version / Public Administration / Master / Master of Public Administration

With the passage of the American with Disabilities Act (ADA) it has become a civil rights violation to deny access to persons with disabilities to public transportation. The ADA requires transit agencies to provide accessible buses or equivalent services to persons with mobility, sensory or cognitive impairments. This study examines issues concerning persons with sensory and cognitive impairments, and their access to fixed route transit services. The goal of this report is: to specify operating guidelines, suggest technological changes, offer operating policy and training programs modifications that solve problems of transit access for persons with sensory and cognitive impairments. To determine where the access problems exist in fixed route transit systems, an examination was undertaken of existing technologies and programs that are in use by transit agencies in North America. Upon review of the available literature it was noted that there were available technologies and policies for persons with visual and hearing impairments, however, little appeared to be available for persons with cognitive impairments. To fill in this knowledge gap, surveys and interviews were conducted with persons with cognitive and other impairments, persons who trained persons with sensory and cognitive impairments, and persons who provide transportation services. A major conclusion of this study is that for persons with cognitive impairments, technological solutions are not the answer to increase bus accessibility. Personal interaction is needed to solve each individual circumstance with the transit user. Training for transit personnel is needed so personnel become aware and more sensitive to the needs of all transit users. Training for the transit user is necessary so use of the transit system is accomplished with grace, speed, efficiency and dignity. Training for the trainers of persons with disabilities is necessary so transit travelers will be informed of all the available services the transit agencies are offering. Another conclusion is visual signage must be standardized to be effective. This includes location, lighting, contrast, and content. / Graduation date: 1993

Thesis (M.S.C.E.)--University of Toledo, 2008. / Typescript. "Submitted as partial fulfillments of the requirements for The Master of Science in Engineering." "A thesis entitled"--at head of title. Bibliography: leaves 81-92.

Thesis (Ph.D.)--University of California, Berkeley, 2009. / Text document (PDF). Title from PDF title page (viewed on April 2, 2010). "Fall 2009." Includes bibliographical references (p. 41-42).

Thesis (Ph. D.)--Illinois State University, 1969. / Title from title page screen, viewed Aug. 24, 2004. Dissertation Committee: Benjamin C. Hubbard (chair), Alan Hickrod, Alic Ebel. Includes bibliographical references (leaves 124-132) and abstract. Also available in print.