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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.
241

Effective Power Consumption in MAC Protocols for Wireless Sensor Networks

Augustin, Angelika January 2006 (has links)
Wireless sensor networks offer easy implementation, flexibility and mobility of hand held devices. Sensors consist of an internal power source, which is the great limitation for the life time and the usage of sensor networks. To increase the life time, sensors should stay in energy saving sleep mode as long as possible, because in sleep mode the radio is either shut down or working with less energy. Better energy handling is implemented in different power saving mechanism of common Medium Access Control protocols, which are evaluated and analyzed and further extensions and ideas to improve the energy efficiency are presented. Slotted PSM is simulated with the NS2 and compared to the WLAN 802.11 PSM technology and the results show that energy efficiency and power consumption are much better implemented and life time increases with the use of Slotted PSM.
242

Design and Analysis of Medium Access Control Protocols for Broadband Wireless Networks

Cai, Lin 17 December 2009 (has links)
The next-generation wireless networks are expected to integrate diverse network architectures and various wireless access technologies to provide a robust solution for ubiquitous broadband wireless access, such as wireless local area networks (WLANs), Ultra-Wideband (UWB), and millimeter-wave (mmWave) based wireless personal area networks (WPANs), etc. To enhance the spectral efficiency and link reliability, smart antenna systems have been proposed as a promising candidate for future broadband access networks. To effectively exploit the increased capabilities of the emerging wireless networks, the different network characteristics and the underlying physical layer features need to be considered in the medium access control (MAC) design, which plays a critical role in providing efficient and fair resource sharing among multiple users. In this thesis, we comprehensively investigate the MAC design in both single- and multi-hop broadband wireless networks, with and without infrastructure support. We first develop mathematical models to identify the performance bottlenecks and constraints in the design and operation of existing MAC. We then use a cross-layer approach to mitigate the identified bottleneck problems. Finally, by evaluating the performance of the proposed protocols with analytical models and extensive simulations, we determine the optimal protocol parameters to maximize the network performance. In specific, a generic analytical framework is developed for capacity study of an IEEE 802.11 WLAN in support of non-persistent asymmetric traffic flows. The analysis can be applied for effective admission control to guarantee the quality of service (QoS) performance of multimedia applications. As the access point (AP) becomes the bottleneck in an infrastructure based WLAN, we explore the multiple-input multiple-output (MIMO) capability in the future IEEE 802.11n WLANs and propose a MIMO-aware multi-user (MU) MAC. By exploiting the multi-user degree of freedom in a MIMO system to allow the AP to communicate with multiple users in the downlink simultaneously, the proposed MU MAC can minimize the AP-bottleneck effect and significantly improve the network capacity. Other enhanced MAC mechanisms, e.g., frame aggregation and bidirectional transmissions, are also studied. Furthermore, different from a narrowband system where simultaneous transmissions by nearby neighbors collide with each other, wideband system can support multiple concurrent transmissions if the multi-user interference can be properly managed. Taking advantage of the salient features of UWB and mmWave communications, we propose an exclusive region (ER) based MAC protocol to exploit the spatial multiplexing gain of centralized UWB and mmWave based wireless networks. Moreover, instead of studying the asymptotic capacity bounds of arbitrary networks which may be too loose to be useful in realistic networks, we derive the expected capacity or transport capacity of UWB and mmWave based networks with random topology. The analysis reveals the main factors affecting the network (transport) capacity, and how to determine the best protocol parameters to maximize the network capacity. In addition, due to limited transmission range, multi-hop relay is necessary to extend the communication coverage of UWB networks. A simple, scalable, and distributed UWB MAC protocol is crucial for efficiently utilizing the large bandwidth of UWB channels and enabling numerous new applications cost-effectively. To address this issue, we further design a distributed asynchronous ER based MAC for multi-hop UWB networks and derive the optimal ER size towards the maximum network throughput. The proposed MAC can significantly improve both network throughput and fairness performance, while the throughput and fairness are usually treated as a tradeoff in other MAC protocols.
243

Hydrogen or syn gas production from glycerol using pyrolysis and steam gasification processes

Valliyappan, Thiruchitrambalam 04 January 2005 (has links)
Glycerol is a waste by-product obtained during the production of biodiesel. Biodiesel is one of the alternative fuels used to meet our energy requirements and also carbon dioxide emission is much lesser when compared to regular diesel fuel. Biodiesel and glycerol are produced from the transesterification of vegetable oils and fats with alcohol in the presence of a catalyst. About 10 wt% of vegetable oil is converted into glycerol during the transesterification process. An increase in biodiesel production would decrease the world market price of glycerol. The objective of this work is to produce value added products such as hydrogen or syn gas and medium heating value gas from waste glycerol using pyrolysis and steam gasification processes. <p> Pyrolysis and steam gasification of glycerol reactions was carried out in an Inconel®, tubular, fixed bed down-flow reactor at atmospheric pressure. The effects of carrier gas flow rate (30mL/min-70mL/min), temperature (650oC-800oC) and different particle diameter of different packing material (quartz - 0.21-0.35mm to 3-4mm; silicon carbide 0.15 to 1mm; Ottawa sand 0.21-0.35mm to 1.0-1.15mm) on the product yield, product gas volume, composition and calorific value were studied for the pyrolysis reactions. An increase in carrier gas flow rate did not have a significant effect on syn gas production at 800oC with quartz chips diameter of 3-4mm. However, total gas yield increased from 65 to 72wt% and liquid yield decreased from 30.7 to 19.3wt% when carrier gas flow rate decreased from 70 to 30mL/min. An increase in reaction temperature, increased the gas product yield from 27.5 to 68wt% and hydrogen yield from 17 to 48.6mol%. Also, syn gas production increased from 70 to 93 mol%. A change in particle size of the packing material had a significant increase in the gas yield and hydrogen gas composition. Therefore, pyrolysis reaction at 800oC, 50mL/min of nitrogen and quartz particle diameter of 0.21-0.35mm were optimum reaction parameter values that maximise the gas product yield (71wt%), hydrogen yield (55.4mol%), syn gas yield (93mol%) and volume of product gas (1.32L/g of glycerol). The net energy recovered at this condition was 111.18 kJ/mol of glycerol fed. However, the maximum heating value of product gas (21.35 MJ/m3) was obtained at 650oC, 50mL/min of nitrogen and with a quartz packing with particle diameter of 3-4mm. <p>The steam gasification of glycerol was carried out at 800oC, with two different packing materials (0.21-0.35mm diameter of quartz and 0.15mm of silicon carbide) by changing the steam to glycerol weight ratio from 0:100 to 50:50. The addition of steam to glycerol increased the hydrogen yield from 55.4 to 64mol% and volume of the product gas from 1.32L/g for pyrolysis to 1.71L/g of glycerol. When a steam to glycerol weight ratio of 50:50 used for the gasification reaction, the glycerol was completely converted to gas and char. Optimum conditions to maximize the volume of the product gas (1.71L/g), gas yield of 94wt% and hydrogen yield of 58mol% were 800oC, 0.21-0.35mm diameter of quartz as a packing material and steam to glycerol weight ratio of 50:50. Syn gas yield and calorific value of the product gas at this condition was 92mol% and 13.5MJ/m3, respectively. The net energy recovered at this condition was 117.19 kJ/mol of glycerol fed. <p>The steam gasification of crude glycerol was carried out at 800oC, quartz size of 0.21-0.35mm as a packing material over the range of steam to crude glycerol weight ratio from 7.5:92.5 to 50:50. Gasification reaction with steam to glycerol weight ratio of 50:50 was the optimum condition to produce high yield of product gas (91.1wt%), volume of gas (1.57L/g of glycerol and methanol), hydrogen (59.1mol%) and syn gas (79.1mol%). However, the calorific value of the product gas did not change significantly by increasing the steam to glycerol weight ratio.
244

The Strategies of Small and Medium Practices (SMPs) for the Adoption of IFRS

Wen, Chiu-Jiuan 27 July 2011 (has links)
The announcement made by the Financial Supervisory Commission, Executive Yuan, R.O.C. for roadmap of the adopting International Financial Reporting Standards (hereafter ¡§IFRS¡¨) on May 14, 2009 was a major earthquake to all companies in Taiwan. The first wave of IFRS adoption will hit all listed companies and those companies in the financial services industry in 2013; and the second wave will hit the rest of the public companies in 2015. To most Taiwanese business entities, IFRS is a brand new accounting principle. They don¡¦t have too many ideas on what IFRSs are, how different are IFRSs from Taiwan GAAP, how IFRS can be adopted, or the size of impact IFRSs will have once it is adopted? When facing all these unknown, the public companies in Taiwan, other than to follow the announcements from the regulatory authorities, can resort to no one but their independent auditors for further assistances. Over the past decade, the Big-4 accounting firms have devoted tremendous efforts in research and development activities on the adoption of IFRSs in accordance with the instructions of their global headquarters. Therefore, at the time when Taiwanese public companies are required to adopt IFRS in accordance with the roadmap, the service opportunities in Taiwan are monopolized by the Big-4 firms, leaving the medium and small practices in Taiwan a competitive disadvantage for entering the market because their resources are very limited. Therefore, it is the goal of this thesis to research and explore the strategies smaller firms may adopt, with limited resources on hand, to expand the service opportunities in the upcoming IFRS era.
245

Applying Visionary Leadership and Balanced Scorecard in the SME ¡VThe Case of Company Y

Huang, Teng-Yu 14 August 2012 (has links)
Along the irreversible trend of globalization, the market competition is getting even more rigorous around the world. Meanwhile, the dynamic revolution of management concept has brought unprecedented challenges for small and medium enterprises. However, amid the era of pandemic internet and smart phone, when small and medium enterprises can utilize the strength of organizational team work, the potential of a greater leaping growth is nevertheless more substantial than the past. As a result, it is even more vital for the small and medium enterprises to consider how to success under the limited resources, pursuing a clear vision, establish a sound company culture, execute a comprehensive management system, to achieve the ultimate goal of maintaining the spring of stamina as countermeasure for ever changing environment. The objective of this study is to investigate the corporate development background of Y company; dissect key successful factors within Y company, while focused primarily on practical experience of incorporating visions and balanced score card as subjects for this research. This study has observed that most companies and institutions failed to successfully implement the establishment of vision and execution of strategies. Primary parameters for such futile endings are usually due to the inconsistency of strategies with regard to communication of strategy, performance assessment, and incentive remunerations. Using balanced score card, managers of small and medium enterprises can develop future direction, substantiate the vision and strategy, and achieve corporate and personal goals. Due to the scale of small and medium enterprises, usually they are relatively more conservative and practical while incorporate new policy, which is likely not to put vast amount of cash and time in vain. Small and medium enterprises can take advantage of strategic transformation via balanced score card to readjust the short term goal and long term development strategy; in order to elevate the competitiveness and commitment of a sustainable business. The approaches for such transformation are : 1. Identify and interpretation of vision and strategy; 2. Assessment, communication and integration of strategic goals and appraisals, set up key performance index; 3. Lay out policies and action plans; 4. Audit the performance, enhance strategic feedback, embrace remediation plans and continuous learning.
246

The Critical Success Factors of implement ERP in SME ¡V Using traditional industry as Example

Lee, Tsung-lung 13 September 2012 (has links)
More than 90% of enterprises in Taiwan are small and medium enterprises. These flexible and efficient forces are one of the important foundations for economic development in Taiwan. How large is the number? Based on the data of ¡§The White book of Small and Medium Enterprises in Year 2011¡¨ from Ministry of Economic Affairs, the number is over one million and two hundred thousand! However; taking on strong competition in emerging markets and enterprise globalization, the small and medium enterprises in Taiwan face many challenges. For large enterprises and electronic industry, implement ERP to manage enterprise resources efficiently to respond to immediate changes is the core of enterprise information technology. With limited budget on information systems and specialties from small and medium enterprises, how should they implement ERP? How could they successfully implement ERP? Should they have change management when implementing ERP? Do they have the same key factors as ERP implementation in the large enterprises? Whether there is any particular attention they should pay on? This study conducted multiple case interviews using semi-structures on the objects of ERP-implemented small and medium enterprises to explore the derivation of the processes of each case, what problems and difficulties have they encountered? How to overcome the problems? By the case corporate practical experiences to assess the key factors of successful implementation, coping with the processes and problems of the implementation derivation, we expected to propose the improvement of core enterprise competition and success rate to the traditional small and medium enterprises that will implement ERP in the future. Keywords: Enterprise Resource Planning, KSF, Traditional Industries, Small and Medium Enterprises, BPR
247

Study in Local-paper Consumer of Purchase Decision-Making Factor

Shih, Yi- Fen 20 July 2004 (has links)
After the newspaper prohibition period, the News industry entry into the diversity free market competition in Taiwan. Each news group and the collective have their own abundant resources to occupy the market. In the past prohibition rule, the local newspaper media industry can not hold the benefit, the issued hurriedly reduced. After that, how to renew to find the market value and the localization, that is mass communication worker and the researcher was very concern question. There are three variables in this research. We focus on the life model variable (includes population statistic), readers satisfy and in need, then marketing promotion strategy. We assume those three variables affect the local paper consumer to purchase policy-making the factor. In this research, we make the questionnaire for these news consumers who stay in the Kaohsiung area. We will inquire the local paper, what is special characteristics can hold the reader after the market redefine? What is factor influence these consumers purchase policy-making? In this research, we will use sample investigation in the ¡§The Commons Daily, Chinese daily and Taiwan News circulation ratio. In Kaohsiung area , we will proceed investigation in subscription household name list , altogether obtains effective sample 315; In another way , I penetrated the chain store to obtains three local newspapers retail 106 household, four nationwide newspaper (union newspaper, the Chinese Times, apple daily paper, liberty Times) retail the household 200 effective samples. After statistical analysis, I find out three main points as following: First, our local newspaper consumer¡¦s age between 35 and 45 years old, month income range between one ten thousand to three ten thousand working race for the main race group, then most of reader belong no party and ¡§pan-green party¡¨. Second, There are 70 % above Kaohsiung area local newspaper consumer satisfies about the local newspaper for the content of local news , the local information, the specific information content, seeks employment classified ad content affect the local newspaper consumer to purchase the policy-making important attribute. Third, local newspaper consumer to local paper opinion standpoint has higher identification, if they can pay attention to newspaper arrangement, printing and set price¡K.etc packaging. It also coordinates effective promotion to be helpful to the local paper marketing. Finally, the researcher discovery on this research suggested the local newspaperman should be concern what the reader in needs, and provide region market for the nationwide newspaper, and refer to relative research with suggestion in the future.
248

A Study of Internet Venture

Lu, Mei-ling 20 July 2005 (has links)
In the internet era,many small-and-medium enterprises begin to engage in e-commerce field.There have been many legends of internet in many contries for the last decade. Traditional enterprises set up their websites and step in the e-commerce continuously. They try to create new entrepreneurial stories. In the past, only large corporations have the capability to perform global business and operate twenty-four hours a day. Because of the sufficient manpower and financial resources, they are proactive in the marketing and customer service. However the internet technology and e-commerce have transformed the traditional business model. Nowadays, small or median enterprises.also can reach global customers and perform the transactions through the internet for twenty-four hours a day. This thesis is about the small and median enterprises to start the e-commerce by joining the H company that is an ISP vendor in Taiwan. This is a multiple cases research containing six internet companies. The research method is the grounded theory. After the interviews and associated data collection, we analyzed the data according to the three steps of grounded theory; they are open coding, axial coding, and selective coding. The internet venture can be described as three stages: starting a business idea, the start-up process, and the internet venture performance. For those internet startups with satisfactory performance, the research summarizes the following characteristics. The entrepreneurs well understand the web skills for internet transaction. Therefore, they pay much attention to the e-business procedures so that they are able to well maintain their websites,and make the best use of the websites to promote their merchandises and to conduct long-term customer¡¦s relationship.On the other hand,for those internet ventures with worse performances, the entrepreneurs usually know little about the e-commerce. They hardly participate their e-shops and have no time to manage their websites. Because they also have low expectation of the e-commerce, they don¡¦t learn the management tactics of inernet venture. For one extreme case, the entrepreneur has never done anything on his website. In this research, it is found that the internet venture performance is positively correlated with the expectation level. The type of merchandise is not the most critical factor to succeed an internet venture. Whenever the entrepreneurs have the higher understanding of the internet technology and the more participation to conduct the e-commerce activities, the performances are always better. Usually, for those startups with proactive entrepreneurs, they have higher possibilities to gain satisfactory financial performance.
249

The Relationship between Leadership Behavior and Organizational Citizenship Behavior: The Effect of Boss¡¦s Wives¡¦ Participative Management in Taiwan Small and Medium Enterprises

Hou, Chia-Li 05 September 2005 (has links)
Taiwan¡¦s small and medium enterprises play an important role in the development of Taiwan economy, and the entrepreneurs and their wives predominate the growth of enterprises with no doubt. Generally, it is convinced that entrepreneur¡¦s wife that is so called ¡§Boss¡¦s Wife¡¨ not only gives the support to her husband in spirit but helps and gets involved in the management or enterprise. The objective of this study is to investigate the relationship between leadership and organizational citizenship organization considering the effect of boss¡¦s wife¡¦s management in Taiwan¡¦s small and medium enterprises. Both qualitative and quantitative methods are used is this study. Three intensive interviews were made to reveal the real sources of management participation from boss¡¦s wife and the reflection of organization citizenship behavior from the employees, and furthermore the implication between leadership and organizational citizenship behavior. Questionnaire survey is used to obtain quantitative data to exam the discovery from case study. Moreover, there is a need for a generic theory development that the contribution of the prosperity of Taiwan¡¦s small and medium enterprises is partly brought by Boss¡¦s Wife¡¦s leadership behavior. The findings are as follows: (1)Leadership behavior of benevolence and moral have positive correlation with organizational citizenship behavior. (2)Leadership behavior of authoritarianism has negative correlation with organizational citizenship behavior. (3)Participative management and leadership behavior have positive correlation. (4)Participative management and organizational citizenship behavior have positive correlation.
250

How do taiwan small and medium-sized enterprices invested in mailand China cope with the business environment.

Lee, Ming-Yen 26 July 2006 (has links)
What kinds of business environmental problems do Taiwan small and medium-sized enterprises that invested in Mainland China have faced? On the other hand, what kinds of factors influence the enterprises management in China¡¦s business environment? How do Taiwan small and medium-sized enterprises cope with business environmental problems in mainland China? In the past, many studies were mainly to investigate problems of the business environment in mainland China by the way of questionnaire which can only realize where the problem have existed, however, it is hard to understand the environmental states which impact on Taiwan enterprises clearly. Because of special culture and social background in China, a lot of problems interlock and coincide with each other, which can not solve the problem in a systematic way. Furthermore, the way of Taiwan small and medium-sized enterprises cope with the business environment in mainland China is related to the role of the owners and how long the owners stay in mainland China. In order to understand how the owners of small and medium-sized enterprises cope with the business environment in mainland China. This study has adapted case study method, a way of qualitative research to collect and analyze data. The propositions are as follows¡G Proposition 1: The basic influence of the business environment in mainland China on Taiwan small and medium-sized enterprises is unable to estimate a cost; therefore, it is difficult for the Taiwan enterprise to finance in mainland China, and cause the enterprise unable to plan its future development. Proposition 2: The owners of Taiwan enterprises are often limited to the experience of life and the way of management in the past, this phenomenon causes the misunderstanding of business environment in mainland China. Proposition 3: In mainland China, a lot of problems interlock and coincide with each other, Taiwan small and medium-sized enterprises can not solve the problem in a systematic way. Proposition 4: The role of the owners of Taiwan small and medium-sized enterprises is the person who solves problems; so it needs to depend on those owners to solve any problems of the business environment in mainland China. Proposition 5: The owners of enterprises must spend whole time and energy on the business, in order to cope with business environmental problems in mainland China. Proposition 6: If the owners of Taiwan small and medium-sized enterprises want to overcome environmental impact in mainland China, they need to keep establishing trusting Guanxi with stakeholders.

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