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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A Theoretical Study to Design an Improved Dispersion Map and the Fiber Effective Area Tolerance for the Long-haul RZ-DPSK System Using the DFF

Kao, Wei-Hsiang 27 June 2011 (has links)
Long-haul optical fiber communication system is an important technology to support the latest broadband communication in the world, and there is strong competition in optical long-haul transmission to achieve high channel bit rates and large transmission capacity. Therefore, it is important to study a technology to improve the performance of such system. As we have already known, return-to-zero differential phase shift keying (RZ-DPSK) is an attractive solution to improve the long distance transmission system performance compared to the conventional on-off keying (OOK) in a 10-Gb/s system, because it has a high nonlinear tolerance. The dispersion flattened fiber (DFF) is attractive for its ability to improve the system performance. Therefore, it is possible to improve the transmission performance by a combination of the RZ-DPSK and the DFF, and one important technology of the current long-haul optical fiber communication system is the dispersion map. And it is widely deployed for already installed undersea optical fiber communication system in the world. A previous study reported that the blockless type dispersion map showed a superior performance than the block type dispersion map, and some efforts to improve the transmission performance of the block type map were conducted. Fundamental idea to improve the transmission performance of the block type map is to reduce the zero crossing points, and one idea is to shift the map toward the positive or the negative cumulative dispersion to reduce the zero crossing points within the map, but it was not so successful. The other idea is to tilt the dispersion map and it was more successful but not good enough. In this master thesis, I continued the study to improve the long-haul RZ-DPSK system performance using the block type dispersion map. One new idea of the dispersion map shifting, the split shifting, was tried, and another new idea of the dispersion map tilting, the split tilting, was examined. The performance with different repeater output power and different compensation scheme within the dispersion map was simulated by a numerical simulator .The goal is, following previous research, to clarify improved dispersion map design of the long-haul RZ-DPSK based transmission and find the effective method to improve the transmission performance. In addition, I also investigate tolerance of the effective area of the transmission fiber theoretically for the long-haul RZ-DPSK system based on the DFF.
2

Retention Strategies for Millennial Long-Haul Truck Drivers

Washington, Debra A. 01 January 2018 (has links)
A persistent truck driver shortage and high driver turnover at common carriers limit the effectiveness of some U.S. supply chains. Most driver vacancies result from job hopping, especially among younger drivers. A multiple case study was conducted to explore strategies that some leaders of U.S. common carriers have used to retain millennial-age long-haul truck drivers. Data sources consisted of semistructured, in-person and phone/videoconference interviews; participant observations; and company documents. The sample population was 9 leaders from 6 different common carriers with operations in the southwestern region of the United States who successfully retained millennial long-haul drivers. The conceptual framework was person-organization fit theory. Data were compiled and organized, disassembled into fragments, reassembled into a sequence of groups, and interpreted for meaning. Methodological triangulation and member checking were used to validate the trustworthiness of those interpretations. Five major themes emerged from data analysis: strategic recruiting, competitive compensation, limiting driver time away from home, facilitating driver comfort while away from home, and demonstrating a company culture of driver appreciation. Potentially, carrier leaders can use the lessons learned from this research to reduce driver turnover rates and operating costs and to improve freight reliability for U.S. supply chains. The implications for positive social change include the potential to lower freight costs to shippers and consumers, improve job satisfaction for long-haul drivers, and improve highway safety for truck drivers and motorists.
3

Theoretical and experimental studies of the APSK format in long-haul optical fiber communication system

Wu, Jyun-Yi 14 July 2008 (has links)
Amplitude and Phase Shift Keying (APSK) format is one of the most attractive advanced modulation formats because of its good spectral efficiency. As the information bandwidth of the current optical fiber communication system is limited by the optical amplifier bandwidth, it is important to utilize the limited bandwidth effectively. This master thesis focuses on to study the transmission performance of the APSK format both theoretically and experimentally. At first, a theoretical study was conducted using a numerical simulation. As the Extinction Ratio (ER) of the Amplitude Shift Keying (ASK) signal affects the performances of both the ASK and the Phase Shift Keying (PSK) signals, the effect of the ER upon the transmission performance of the APSK format was studied. A clear trade-off between the performance of the ASK signal and the PSK signal due to the change of the ER was observed. Then, in order to improve the performance of the APSK format, a method to improve the transmission performance was proposed. This method was named as ¡§zero-nulling method¡¨, and it solved the trade-off issue caused by the ER. The effectiveness of this method was confirmed through the numerical simulation. Next, an experimental study was conducted. An experimental setup including 330km optical fiber transmission line was prepared, and it was used to confirm the results of the theoretical simulation. The performance trade-off between the ASK and the PSK signals due to the ER was confirmed experimentally. Finally, another experimental study was conducted. An experimental setup of 500km transmission line was used for this study. By adopting the recirculating loop experimental setup, the transmission length could be extended to a few thousand kilometers. The applicability of the ¡§zero-nulling method¡¨ was confirmed using this experimental setup.
4

Implications of Long Haul Travel on the Marketing of International Tourism

Harrison-Hill, Tracey, n/a January 2001 (has links)
Tracking studies conducted by the Australian Tourist Commission (ATC) over the last decade have revealed that Australia has a high ranking as a desired destination among US residents. However prior to the peaked effect of the Olympics, this desire had not translated into increasing numbers of visitor arrivals from the US. As travel to Australia from the US is time consuming and involves extremes of physical distance, it would be to Australia's advantage to understand better the dimensions and ramifications of long haul travel with regard to destination choice. This thesis has two objectives: to assess the extent to which a destination being a long haul from its target market affects the choice of this destination; and to consider the marketing implications of the above with a focus on the selection of Australia, as compared to competitive destinations, by the US holiday market. Data were collected from two samples: the West Coast of the US and the East Coast of Australia. The instrument for the US sample collected information on the respondents' choice set structure, attribute importance in selecting a long haul destination, perceptions of the long haul destinations of Australia and Italy, and sociodemographics. The instrument for the Australian sample collected information on the respondents' choice set structure, attribute importance for both long haul and short haul destination selection, perceptions of the long haul destination of the US and the short haul destination of New Zealand, and sociodemographics. This data were then used to test nine hypotheses designed to give insight into the research objectives. The results indicate that tourists place differing degrees of importance on attributes of a long haul destination as compared to a short haul destination for a vacation. It also demonstrates that tourists' perceptions of the distance to destinations are often highly inaccurate and that this inaccuracy is related neither to actual distance nor choice set placement. The cognitive distance is however directly related to perceptions of cost of travelling to the destination. A conundrum was also established in that the distance to Australia was overestimated and related positively with the choice of the destination. Yet at the same time the overestimation led to increasing perceptions of cost, travel time and risk, which indirectly had a negative impact on the choice of the destination. This far-off allure was not evident for the equidistant competitor, Italy, where the cognitive distance was underestimated. It was also found US respondent's place differing importance on the attributes they seek in a long haul destination as compared to the Australian respondents. Notably, the US market places a significantly higher importance on distance, even though their estimation of the distance between Australia and the US did not differ from the Australian estimate. Marketing implications for Australia as a long haul destination were then considered with an emphasis on redefining vacation distances in tourists' minds without relinquishing the far-off allure. The relationship between cognitive distance and perceptions of cost and time in comparison to competitors were driving the need for redefining distance. Emphasis was placed on delivering information to tourists during their decision process when their involvement and information processing was highest. Direction was also given for future research that would be useful for travel marketers in gaining additional insight into their long haul target markets.
5

Interactive Television and Tourism Marketing WA to the UK Pleasure Travel Market through Interactive Television Applications

A.Schweda@murdoch.edu.au, Anika Schweda January 2004 (has links)
As an information intensive industry and as one of the most progressive industries in information technology adoption, travel and tourism provides an ideal context in which to investigate how new technologies such as interactive television challenge our understanding of media and media use. This research looks at how interactive television can be used by consumers and how it may be best applied by marketers in international holiday travel. Using the UK international traveller market to Western Australia as case in point, this research had three main research goals: 1) to understand how travellers use information sources with a focus on interactive television; 2) how an individual’s previous interactive media and travel experiences may pre-dispose them to using interactive television; and 3) to better understand why individuals interact and what impact the interaction has on the promotional effort. A travel ad and a travel show segment were used to explore these with impulse (brochure request) and telescopic (destination video) interactive opportunities. The treatments were deployed over a video-on-demand platform in greater London and participants took part in their homes via their televisions and a self administered questionnaire. This research has furthered the use of the multi-dimensional grid in understanding information sources in relationship to one another and updated the landscape with modern information sources such as television, teletext, the Internet and interactive television. Findings from this area of investigation suggest that current interactive television offerings cater better to short-haul destinations and although it currently plays a minor role, interactive television has the potential to significantly contribute to travellers’ long-haul holiday planning process. The finding that individuals understand interactive television through their experience with teletext rather than the Internet and are more likely to use interactive television if they are thorough and experienced planners supports the theory of knowledge transference. However, most importantly, if an individual has a positive experience with interactive television they will interact again in the future. Contributions were also made to a better understanding of the interactive television user and the use of interactive television applications to the travel and tourism industry in particular. Exploration of the differences between the Impulse and Telescopic approaches to interactivity highlighted that while interactivity generally enhances the promotional effort each approach has its own strategic applications.
6

Can the low cost boom in aviation reach long distance destinations? : MBA thesis in marketing

Sturesson, Vladka January 2011 (has links)
Aim The commercial success of some low cost airlines presents the low cost model as very attractive. Until now their main focus has been on short-haul routes, but it is no surprise that they show an interest in entering the long-haul routes market as recent trends are very promising. The aim of this study is to analyze whether the low cost business model is applicable for long-haul routes, which parts of the model are transferable to long-haul services, what competitors responses might be and whether there is potential for low cost airlines operating in Scandinavia to gain frequent, well paying and demanding business travelers on their future long-haul routes. Method In this study a survey method with structured questionnaire distributed by e-mail has been used to collect the primary data. The main source of secondary data has been airline industry literature, newspapers, magazines and data provided by aviation statistical organizations. The empirical part of this study is conducted as a quantitative and qualitative study. Intention of empirical part is to find detailed information and describe business travelers’ behavior, corporate travel policies, business trips pattern and attitude towards low cost airlines. Conclusions The cost savings that low cost airlines achieved in the short-haul market will be much more difficult to achieve to long-haul services. In terms of areas where airlines can achieve cost leadership labor costs is certainly the best area to attack. To be successful, low cost airlines would have to adopt some elements of the traditional business model. But the success of long-haul low cost airlines will not only depend on achieving cost advantages. Availability of leisure time for long-haul trips and response of competitors will be other factors. Suggestions for future research A deeper analysis of low cost long-haul airlines potential could be possible with survey among leisure travelers and VFR (visiting friends and relatives) segment. Contribution of the Study This study has arrived at the conclusion that in order to be successful on long-haul routes low cost airlines would have to keep most of the features of traditional airlines. Low cost long-haul airlines would most probably be successful in pure leisure routes, ethnic markets, during peak season and on dense point to point destinations.
7

A Theoretical Study of the Dispersion Map upon Long-Haul RZ-DPSK and RZ-DQPSK Transmission System

Fei, Jing-Wen 16 July 2012 (has links)
Nowadays, the long-haul optical fiber communication system is one of the important way to convey the information, and there is strong competition of research in the optical long-haul transmission to achieve high channel bit rates and large transmission capacity. Therefore, it is important to study a technology to improve the performance of such system. The return-to-zero differential phase-shift keying (RZ-DPSK) and the return-to-zero differential quadrature phase-shift keying (RZ-DQPSK) have received renewed attention recently for the long-haul transmission systems, because they can improve the transmission performance of the long-haul system. Furthermore, the design of the dispersion map becomes significantly different from that of the conventional system using the intensity modulation direct detection (IM-DD) scheme. Besides, the RZ-DQPSK can transmit two bits per symbol, so it has twice the spectral efficiency of the RZ-DPSK. This study is focusing on the difference of the transmission performance of the long-haul RZ-DQPSK system due to the dispersion map using the numerical simulation.
8

Parallel Hybridization of a Heavy-Duty Long Hauler

Eriksson, Tommie January 2015 (has links)
Long haulage of heavy-duty trucks weighing over 15-ton stands for nearly 50% of the fuelconsumption among trucks, making them the most fuel consuming category. This indicatesthe potential benefits in improving the fuel efficiency for said category. Hybridization is onepossible solution.Hybrid vehicles are vehicles with two or more power sources in the powertrain. Differentpowertrain configurations, hybridization levels and hybrid concepts are best suitedfor different applications. With prices for fossil fuels constantly rising hybridization is animportant technology to improve fuel efficiency.Different variations of configurations and concepts enables many choices when decidingon a hybrid driveline. A simulation tool for efficiently comparing various hybrid drivelineswould be a great asset when deciding on a configuration for a certain vehicle application. Forthis thesis the application in focus is the previously mentioned category, a heavy duty longhauler weighing 36-ton.The modeling approach used for the simulation tool is called quasistatic modeling or"backward modeling". This name comes from, based on a chosen drive cycle, the resistingforces which act on the vehicle can statically be calculated at each step from the velocityprofile. The required power to drive along the drive cycle can then be calculated backwardswithin the powertrain resulting in a fuel consumption for the combustion engine. For thisthe free QSS-toolbox for Matlab Simulink has been used as a base and modified when needed.The configuration chosen to be implemented is a parallel electric hybrid and was chosenfor its good characteristics for the type of driving highways provide. For this configurationtwo types of controllers are used, one being an Equivalent Consumption Minimization Strategycontroller and the other a simple, rule based heuristic controller.The results for both controllers show small benefits with hybridization of the longhauler compared with the conventional which in the long run would make bigger differencebecause of the large consumption in whole. A sensitivity analysis was also done showingthat improving conventional vehicle parameters can be as beneficial as hybridization.
9

Advanced Signal Processing for Fiber-Optic Communication Systems Scaling Capacity Beyond 100 Tb/s / 光ファイバ通信システムの100 Tb/s容量限界の克服へ向けた信号処理技術

Shibahara, Kohki 25 September 2017 (has links)
Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(情報学) / 甲第20740号 / 情博第654号 / 新制||情||113(附属図書館) / 京都大学大学院情報学研究科通信情報システム専攻 / (主査)教授 守倉 正博, 教授 大木 英司, 教授 梅野 健 / 学位規則第4条第1項該当
10

Education Resource Guide: Jeff Kinney’s ‘The Long Haul’

Lyons, Reneé C. 01 January 2017 (has links) (PDF)
This Education Resource Guide includes discussion questions, as well as activities regarding the following three topics related to Diary of a Wimpy Kid: The Long Haul.

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