Bicycle network for a renewed "bicycle kingdom"

Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 120-121).This thesis intends to be a catalyst for a renewed bicycle culture in Beijing, the capital of the former "Bicycle Kingdom". Beijing, only 15 years ago had more bicycles than any other city in the world, has in recent years undergone a drastic shift to become a city consumed by cars and highways, producing disruptive voids in the traditional small-scale fabric of the city that once made the old city unique. It has also produced the worst traffic in the world as well as some of the worst air pollution problems that any city has ever seen. This ironic shift from a city dependent on the most sustainable form of transit to one that is gridlocked by the form that is the least sustainable is what the thesis will critique. Recognizing that this shift is largely attributed to the changing culture of the citizens as they gain higher economic status, the thesis will attempt to create a project which creates a counter-culture to the current trend toward motor vehicles. It will target the population of the white-collar working class as its main audience, as they are the ones which are setting the trends of contemporary transportation in Beijing. The thesis proposes a new building typology for the city -a bicycle transit center which will occupy the void space produced by the highways. The center will provide an 'oasis' in the city, a place which promotes a lifestyle of wellness and sustainability centered around the daily bicycle commute - a lifestytle antithetical to that of the motor vehicle. The driving concept is "auto"-mobile lifestyle, derived from the literal meaning of the word for "bicycle" in Chinese: zi M ("auto/self") xing 'i ("mobile/sufficient") che * ("vehicle").by August Liau.M.Arch

Influence of atomic mixing and preferential sputtering on depth profiles and interfaces

Atomic mixing and preferential sputtering impose a depth resolution limit on the use of sputter sectioning to measure the composition of metal–semiconductor interfaces. Experimental evidence obtained with the Pt–Si system is used to demonstrate ion‐induced atomic mixing and then its effect on sputter etching and depth profiling. Starting with discrete layer structures, a relatively low ion dose (≳3×10^(15) cm^(−2)) first produced a mixed surface layer with thickness comparable to the ion range. Higher ion doses then result in successive sputter etching and continual atomic mixing over a constant surface layer thickness. A model is developed that is based on a sputter removal (including preferential sputtering) of atoms at the surface and a uniform mixing of atoms over a constant thickness. The model predicts the influences of atomic mixing and preferential sputtering on the depth profiling of thin‐film structures and interfaces

Factors Influencing Senior Secondary School Retention in Malaysia

In this thesis a model to predict whether Form Five students in six secondary schools in Malaysia would continue with their Form Six studies and maintain their career aspirations was tested and the influence of motivation as a mediating variable was examined. There are two public examinations in Malaysia, which are not only important to the students themselves but also to their parents and to the employers who will be seeking credentials. The aspirations of students for their future careers are dependent on their performance at the Form Five public examination and the second Form Six public examination. This study sought to examine whether their performance at the Form Five examination was affected by their family background, goal commitment, school achievement, school commitment, social integration, and academic integration, and to examine whether these factors could separately or together influence a student\u27s motivation to enter Form Six and later pursue tertiary education. Questionnaires were administered to 377 Form Five students before their Final Form Five examinations. Interviews were conducted after the administration of the questionnaires and after the release of the Form Five examinations results, some months later. Statistical analysis making use of the SPSS/PC statistical package and the Windows for SPSS was used, and it was found that the theoretical model did predict which students would proceed to Form Six and which would leave school at the end of Form Five

Dissociation mechanism for solid-phase epitaxy of silicon in the Si <100>/Pd2Si/Si (amorphous) system

Solid-phase epitaxial growth (SPEG) of silicon was investigated by a tracer technique using radioactive 31Si formed by neutron activation in a nuclear reactor. After depositing Pd and Si onto activated single-crystal silicon substrates, Pd2Si was formed with about equal amounts of radioactive and nonradioactive Si during heating at 400 °C for 5 min. After an 1-sec annealing stage (450-->500 °C in 1 h) this silicide layer, which moves to the top of the sample during SPEG, is etched off with aqua regia. From the absence of radioactive 31Si in the etch, it is concluded that SPEG takes place by a dissociation mechanism rather than by diffusion

Two-path succesive relaying schemes in the presence of inter-relay interference

Relaying is a promising technique to improve wireless network performance. A conventional relay transmits and receives signals in two orthogonal channels due to half duplex constraint of wireless network. This results in inefficient use of spectral resources. Two-Path Successive Relaying (TPSR) has been proposed to recover loss in spectral efficiency. However, the performance of TPSR is degraded by Inter-Relay Interference (IRI). This thesis investigates the performance of TPSR affected by IRI and proposes several schemes to improve relaying reliability, throughput and secrecy. Simulations revealed that the existing TPSR could perform worse than the conventional Half Duplex Relaying (HDR) scheme. Opportunistic TPSR schemes are proposed to improve the capacity performance. Several relay pair selection criteria are developed to ensure the selection of the best performing relay pair. Adaptive schemes which dynamically switch between TPSR and conventional HDR are proposed to further improve the performance. Simulation and analytical results show that the proposed schemes can achieve up to 45% ergodic capacity improvement and lower outage probability compared to baseline schemes, while achieving the maximum diversity and multiplexing tradeoff of the multi-input single-output channel. In addition, this thesis proposes secrecy TPSR schemes to protect secrecy of wireless transmission from eavesdropper. The use of two relays in the proposed schemes deliver more robust secrecy transmission while the use of scheduled jamming signals improves secrecy rate. Simulation and analytical results reveal that the proposed schemes can achieve up to 62% ergodic secrecy capacity improvement and quadratically lower intercept and secrecy outage probabilities if compared to existing schemes. Overall, this thesis demonstrates that the proposed TPSR schemes are able to deliver performance improvement in terms of throughput, reliability and secrecy in the presence of IRI