Stability and safety estimates and tests of a superconducting bus-line for large-scale superconducting coils

We have been developing a flexible superconducting bus-line as a unit electrical feeder between large-scale superconducting coils and their power supplies away from the coils. The designed superconducting bus-line consists of a pair of +/- aluminum stabilized NbTi/Cu compacted strand cables and a coaxial four-channel transfer line. A full-scale model of the SC bus-line (20 m long) has been constructed and tested successfully up to 40 kA without a quench under the short-circuit condition. Stability tests were also done by inducing a forced quench with heaters. A minimum propagation current larger than 32.5 kA was confirmed. Thus, the bus-line was cryogenically stabilized at the rated current of 30 kA. We have examined the test results and evaluated the stability and safety margins of this bus-line. The design criteria for a superconducting bus-line are also shown for large-scale superconducting coils with operating current as a parameter

Des différences entre les plans des transports publics en France, en Allemagne et en Espagne

Les plans des transports publics en France présentent un style commun parce qu'ils attribuent une couleur différente à chaque ligne d'autobus. Selon les villes, des solutions diverses ont été apportées au problème inévitablement posé par la représentation de multiples lignes de bus et du schéma spatial des différentes lignes. Au contraire, les plans allemands et espagnols des réseaux de transports publics adoptent des représentations beaucoup plus variées. Les raisons en sont les différences entre les modes de transport utilisés, le niveau des subventions accordées aux transports publics et le degré de centralisation politique des trois pays respectifs

Circle Line Optimization of Shuttle Bus in Central Business District without Transit Hub

The building density of Central Business District (CBD) is usually high. Land for a bus terminal is insufficient. In this situation, passengers in CBD have to walk far to take a bus, or take a long time to wait for a taxi. To solve this problem, this paper proposes an indirect approach: the design of a circle line of shuttle bus as a dynamic bus terminal in CBD. The shuttle bus can deliver people to the bus station through a circle line. This approach not only reduces the traffic pressure in CBD, but also saves travel time of the passenger. A bi-objective model is proposed to design a circle line of a shuttle bus for CBD. The problem is solved by non-dominated sorting genetic algorithm (NSGA-II). Furthermore, the Dalian city in China has been chosen as the case study to test the proposed method. The results indicate that the method is effective for circle line optimization of shuttle bus in central business district without a bus terminal

Data-Driven Design of On-Demand Multimodal Transit Systems

Across the United States, public transit agencies are facing trends of decreasing ridership. Especially during and since the COVID-19 pandemic, reduced ridership caused many agencies to have significant budget deficits due the to the high-fixed cost of traditional transit systems. Many transit planners are exploring network redesign to address these changing ridership patterns and their budget deficits. On-demand services have previous been used in smaller cities, and more rural areas and for paratransit services, but now larger cities are starting to explore using on-demand services to help supplement their fixed route services to create a more accessible and scalable system. On-demand Multimodal Transit Systems may be an accessible, scalable solution for first and last mile issues that often plague many transportation systems. Chapter 2 presents a novel methodology to help transit agencies with their tactical planning for post-game ridership of large events. The methodology has three main steps: (1) predicting the total post-game ridership; (2) combining the total prediction with historical trends to forecast the passenger flow curve at nearby stations after the game; and (3) estimating the required train frequencies to serve these customers with minimal passengers left behind by each train. Additionally, this chapter proposes a suite of data-driven techniques that together create a data-driven pipeline to exploit Automated Fare Collection (AFC) data for evaluating, anticipating, and managing the performance of transit systems. This chapter includes a case study where the proposed pipeline is used to generate an adjusted train schedule for the post-game period and simulated with the rail ridership data from the Metropolitan Atlanta Rapid Transit Authority (MARTA). The simulation results highlight how the proposed schedules based on the estimated required post-game train frequencies could significantly improve post-game congestion and wait time. Chapter 3 studies the resiliency during a pandemic of On-Demand Multimodal Transit Systems (ODMTS), a new generation of transit systems that combine a network of high-frequency trains and buses with on-demand shuttles to serve the first and last miles and act as feeders to the fixed network. A limit is imposed on the number of passenger transfers with a new network design model leveraging a transfer-expanded graph. It presents a case study for the city of Atlanta and evaluates ODMTS for multiple scenarios of depressed demand and social distancing representing various stages of the pandemic. The case study relies on a real data from MARTA, an optimization pipeline for the design of ODMTS, and a detailed simulation of these designs. The case study demonstrates how ODMTS provide a resilient solution in terms of cost, convenience, and accessibility for this wide range of scenarios. Chapter 4 addresses to what extent On-Demand Multimodal Transit Systems (ODMTS) in combination with Dedicated Bus Lanes (DBLs) improve the attractiveness of public transit under various congestion scenarios. Previous case studies have shown that ODMTS may simultaneously improve travel time, reduce system cost, and attract new passengers compared to existing fixed-route systems. However, none of these studies include the effect of congestion on the travel times, adoption, and cost of the ODMTS. This paper introduces new methods to help model the ODMTS under various congestion scenarios as part of a case study in the Metro Atlanta Area, analyzing the system both with and without DBLs. The results show that an ODMTS with DBLs and synchronization could make public transit a viable, accessible option for many more people, especially in currently underserved areas. Higher congestion actually leads an ODMTS with DBLs to be faster than a direct trip by car in some cases by mitigating the negative impact of congestion on the most congested corridor. Chapter 5 presents a novel mixed-integer program (MIP) formulation to incorporate bus line design into the network design problem for On-Demand Multimodal Transit Systems (ODMTS) that allows the model to accurately capture wait time and transfer costs in addition to travel time and vehicle costs. To solve large-scale instances, a two-stage reformulation is presented where the first-stage problem decides which bus arcs to open and decides which arcs immediately follow and the second-stage problem decides the multimodal path for each individual trip. The solution method is based on the Benders decomposition method and uses disaggregated subproblems and Pareto-optimal cuts. This chapter includes a case study of the Metro Atlanta Area with instances that have up to 43,000 unique trips and hundreds of bus arcs for potential lines. The results show there was a significant reduction in number of transfers for individuals when considering the bus lines as part of the network design phase.Ph.D

Analysis and evaluation in the production process and equipment area of the low-cost solar array project

The effect of solar cell metallization pattern design on solar cell performance and the costs and performance effects of different metallization processes are discussed. Definitive design rules for the front metallization pattern for large area solar cells are presented. Chemical and physical deposition processes for metallization are described and compared. An economic evaluation of the 6 principal metallization options is presented. Instructions for preparing Format A cost data for solar cell manufacturing processes from UPPC forms for input into the SAMIC computer program are presented

a case of Daegu in Korea

Thesis(Master) --KDI School:Master of Public Policy,2011The purpose of the study is to analyze the correlation between hosing prices and educational performance, and to specifically interpret the correlation as a nationwide matter. This study, therefore, focuses on Daegu Metropolitan City, a region excluding the Seoul Metropolitan Area where precedent researches were made already. Meanwhile, this study employed the hedonic pricing model being widely used in related academic and practical fields. With that model, two research hypotheses are developed as follows: first, the educational performance in this city influences the condominium prices linearly or nonlinearly; second, the influence changes by lapse of time. To clarify the influence in depth, multifarious analyses are attempted so that Chapter 4 provides a variety of analyses composed of an OLS regression, a time-series analysis, a dummy-variable regression and a panel data analysis. Through these analyses, several key findings are obtained as in the following: 1) the price of a condominium of which the lot size is thirty pyeongs (one hundred square meters) goes up by approximately KRW 13.6 million as of 2009 in terms of the statistic-economics, when an adjacent high school has one more student admitted into the Seoul National University; 2) the magnitude of the influence has increased by average 18.5 percent per annum for five years from 2005 to 2009; 3) the condominium price and the educational performance holds a nonlinear correlation so that, if a student who gains the admission into the Seoul National University belongs to a high school which sends more than ii seven students to the top-class university, the condominium price gets almost doubled; 4) lastly, through the panel data analysis, this study identifies the facts that the influence of unobservable omitted variables is not critical and the most decisive factor by which determines the value of residential real estate in Daegu Metropolitan city is the educational performance.Outstandingmasterpublishedby Yoonsan Kim

Growth, Evolution and Scaling in Transport Networks

Under urbanisation, transport infrastructures may be improved when urban population grows. Meanwhile, land use patterns may vary and this urban dynamics may drive variations in mode choice of commuters and spatial features of transport networks. Empirical studies have observed scaling laws between the amount of transport infrastructures and city sizes. This thesis is aiming to provide a modelling framework for the analytical investigation of network growth and present some empirical observations of the variation in spatial features of transport networks. First, a simple linear monocentric city model is formulated and the global performance of transport systems is derived. Two cases according to strategies of urban intensification and sprawl have been studied to examine the consequence of the scaling-law growth in transport infrastructures. Second, this thesis proposes a modelling framework. The framework includes two congestible modes, the scaling-law growth of transport infrastructures and housing allocation of residents so that phenomena under urban dynamics could be modelled. The experiments show that the proposed modelling framework could investigate the trade-off of investment on the highway and public transport system. Third, empirical observations of spatial features in transport networks are reported in this thesis. The thesis measures circuity of transport networks, because this indicator could examine how aggregate transport networks are and the efficiency of network structures. Then research methods that can deal with several data sources are developed. The empirical observation shows that there is an exponential decay between the circuity and travel time in public transport networks. Meanwhile, this thesis also presents that the average circuity in road networks is less than that in public transport networks for the same sample of trips, which to some extent show the difference of spatial features between road and public transport networks. Additionally, correlations between circuity, accessibility and mode share are analysed

A straightforward method for shuttle-bus line design under urban rail transit emergencies

10.1080/19439962.2019.1645775Journal of Transportation Safety & Security13101093-111

Matrix-addressable III-nitride light emitting diode arrays on silicon substrates by flip-chip technology

Matrix-addressable light emitting diode (LED) micro-arrays on sapphire substrates have been reported. In the fabrication process, complicated chemical-mechanical polishing after planarization with oxides, or conformal sputtering metallization process were needed to ensure smooth metal interconnections. The resistance of each individual device was reported to depend strongly on the n-type GaN stripe length and distance of the die from the contact at the end of the column, leading to significantly larger turn-on voltages with great variation. We have developed a simpler and more reliable fabrication process with much improved performance using a flip-chip configuration on a silicon wafer. The p-type contact aluminum bus lines were fabricated on the silicon carrier under the solder bumps, with very simple steps. The contact pads of the matrix were formed on the silicon wafer, with light emitting from the sapphire side. A high resolution 8x8 LED dot matrix display has been designed and fabricated. An individual device size was 300x300μm2. The turn-on voltages of the devices on the display were found to be strongly dependent on the n-type metal bus line design. Various n-type metal bus line designs were fabricated on the same LED wafer for investigation. Our optimum design showed an average turn-on voltage of the matrix fabricated on the same LED wafer not much higher from individual ones fabricated with conventional process. The variation was also small, from 3.21V to 3.36V. The matrix was flipped onto the silicon wafer afterward. We demonstrated that each LED on the matrix was addressed and lit up successfully. 2mm x 2mm large LED with two different designs were also fabricated from the same fabrication process as the dot matrix display. These large LED provided higher wall-plug efficiency than the standard 0.3mm x 0.3mm LED at the injection current density range (0-225mA/mm2)