In this thesis, the main objective is to identify the resilient deformation behaviour of rail trackbed especially in ballast and calculate the stress distribution. A purpose-designed three dimensional Finite Element railway trackbed model is presented in which linear elastic behaviour is assumed in all parts of the model. The study has also evaluated the effects of different variables including moving load magnitude, loading speed and stiffness of materials on stress conditions and deflections based. A comprehensive literature review on a wide background of railway trackbed has been carried out. Railway ballast specifications, deformation mechanisms, resilient and permanent deformation behaviour of granular material, introduction of fouling material and its influence on ballast behaviour are explained to provide the basis for trackbed analysis. Results show that a higher vertical displacement underneath the sleeper may occur when the loading speed is higher than 120km/h. Also, higher speed and Young’s modulus of ballast can result in higher damaging stresses. A stiffer subgrade can result in less rotation of sleeper. A significant effect of subgrade stiffness on stress paths and rotation of sleeper can only be found when Young’s modulus of subgrade is in a low level. Stiffer rail pad can lead ballast element get cracked more easily. Softer pad results in less damaging stresses. In addition, there is no obvious change of either the stress ratio or sleeper rotation as stiffness of the ballast increased.

Maintenance management decision-support systems are needed to help senior decision-makers and asset managers to better plan timely and efficient maintenance. Within the railway industry, several maintenance management decision-support systems have been developed. However, most these operate at project level where decisions are limited to short sections of track. Network level maintenance management systems enable future prediction of the condition of the railway network under different allocation of resources in a manner to provide acceptable levels of safety, reliability and cost. This project describes the development of a theoretical framework for the strategic assessment of network level railway maintenance funding and policy decisions. The model is designed to aid railway asset managers in planning medium to long-term maintenance investment requirements for the railway network. The model is based on stochastic processes which are capable of determining the effects of traffic, maintenance and climate on network condition under any budget scenario.

Ballasted track represents by far the most used infrastructure for railway transportation system, its main benefits being the relatively low construction costs, the maintainability, the relatively high damping capacity, noise absorption and high flexibility, the self-adjusting properties and high hydraulic conductivity. These are related to the structure of ballast layer as assembly as well as to particle properties. However, the unbound nature of ballast layer is also responsible for the reduction of geometric quality of the track, and therefore, its safety and ride comfort. The passage of trains causes cyclic movements of the unbound particles that result in permanent vertical and lateral deformations. For this track form, vertical settlement of granular layers and ballast particles degradation represent the major problems, affecting frequency of maintenance and track durability. In this context, reducing minor and major maintenance frequency while effectively using available resources by developing innovative technologies is a challenge for current and future railway research. After reviewing the most relevant existing solutions to improve ballasted track-bed behaviour and main factors affecting their performance, the aim of this research was to investigate the possibility of stabilising ballast with bitumen emulsion, as novel solution to slow down the loss in track quality associated with ballast settlement and particle degradation. In this regard, firstly the feasibility of the proposed alternative and main factors affecting its performance have been assessed through model-scale testing (small-scale Precision Unbound Material Analyser - PUMA). Results showed a good potential for this technology to reduce both the short-term and the long-term permanent deformation. It was also observed that bitumen stabilisation could modify mechanical properties due to the presence of a viscoelastic component (bitumen). The type of emulsion and its dosage played important roles in BSB properties: increasing the dosage of bitumen emulsion provided a better resistance to permanent deformation; increasing the viscosity of bitumen emulsion decreased the percentage of material lost, thereby providing improved stabilisation efficiency. Thus, depending on the field condition a specific bitumen emulsion could be designed to obtain the desired results in terms of BSB behaviour and stabilisation efficiency. At the same time, the use of harder bitumen for BSB seemed to improve the resistance to permanent deformation while polymer modification provided a more stable behaviour over time. Model-scale results provided important guidance on the influence of the factors analysed on the proposed technology. Nevertheless, to understand to what extent BSB could represent a solution to improve sustainability and performance of ballasted track-beds, findings had to be verified at full scale. Thus, full-scale box tests have been employed to assess how this technology could be effectively applied to existing ballasted tracks during maintenance operations and to investigate the practicability and maintainability of the presented technology. Results showed that bitumen stabilisation was more effective when applied at an early stage of ballast life (clean ballast), especially when coupled with tamping, providing a significant decrease to permanent deformation and to deformation rate (long-term behaviour). Nonetheless, in comparison with results obtained at model-scale, a slightly different behaviour of BSB in relation to unbound material was observed. Thus, with the aim of correlating previous model-scale PUMA and full-scale ballast box findings and evaluating long-term performance, full-scale PUMA testing was carried out. Results on clean ballast indicated that scale factor instead of the test type was the main factor controlling the effectiveness of Bitumen Stabilised Ballast (BSB) in terms of permanent deformation reduction. On the other hand, results obtained when using lower size aggregate confirmed that increasing the number of contact points increases also the influence of viscoelastic properties given by the bitumen, indicating that the use of different gradations combined with higher dosages (and types) of bitumen emulsions, could potentially modify full-scale track-bed mechanical properties. Key findings obtained from laboratory experiments, consistently showed evidence of the fact that bitumen stabilisation can reduce number of maintenance interventions due to geometry corrections and excessive particle degradation. In this regard, to estimate the environmental and economic impacts of BSB, a performance-based integrated model was developed to predict maintenance strategies of proposed technology in comparison to traditional ballast. This model, by combining the evolution of track irregularities with traffic and the level of contamination of ballast, allowed evaluation of the timing of corrective maintenance activities. Based on these, life-cycle environmental and economic costs of these alternatives have been carried out. Life Cycle Assessment (LCA) results showed that BSB is overall more sustainable than traditional ballasted track, only when considering also its impact on major maintenance operations. Sensitivity analysis carried out showed that BSB advantages are generally higher when the tolerance on the track quality level increases and with heavy traffic lines. LCCA results showed that BSB can provide important savings with respect to traditional ballasted track-bed. Sensitivity analysis showed that BSB would be more profitable for important and congested lines rather than peripheral ones. The influence of carbon conversion factor on results is relatively low while decreasing the discount rate corresponds to higher savings provided by the BSB. Overall, both LCA and LCCA results showed that BSB could offer a more sustainable solution from a life cycle perspective than traditional ballasted track-bed.

Thesis (Ph. D.)--Texas A&M University, 2005. / "Major Subject: Information and Operation Management" Title from author supplied metadata (automated record created on Feb. 23, 2007.) Vita. Abstract. Includes bibliographical references.

Poverty alleviation strategies

Women multipurpose co-operative societies in Karnataka

Landless agricultural labour

The current waste management strategy for spent nuclear fuel (SNF) mandated by the U.S. Congress is the disposal of high-level waste (HLW) in a geological repository at Yucca Mountain. Ongoing efforts on closed-fuel cycle options and difficulties in opening and safeguarding such a repository have led to investigations of alternative waste management strategies. One potential strategy would make use of fuels containing transuranic (TRU) nuclides in nuclear reactors. This would prolong reactor operation on a single fuel loading and by doing so, would reduce current HLW stockpiles. The analysis has already shown that high-temperature gas-cooled reactors (HTGRs) and their Generation IV extensions, very-high-temperature reactors (VHTRs), have encouraging performance characteristics that will allow for prolonged operation with no intermediate refueling, as well as for transmutation of TRUs. The objective of this research was to show that TRU-fueled VHTRs have the possibility of prolonged operation on a single fuel loading while retaining their Generation IV safety features. In addition, this research evaluated performance characteristics, and identified operational domains of these systems, as well as the possibility of HLW reduction. A whole-core, 3-D model of a power size prismatic VHTR with a detailed temperature distribution was developed for calculations with the SCALE 5.1 code package. Results of extensive criticality and depletion calculations with multiple fuel loadings showed that VHTRs are capable and suitable for autonomous operation when loaded with TRU fuel.

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Taiwan has become the international supply center of the TFT-LCD panel since its investment in the field for the past decade. Besides the main application in the products such as notebooks, LCD monitors, and LCD TVs, other consuming electronic goods also take it in wide-range application. Suppliers keep on investing, building new factories. After semiconductor industry, TFT-LCD panel has become another representative of Taiwan industry. Facing a competition with international companies, the factories of Taiwan TFT-LCD panel must be internationalized and configured in order to approach market and satisfy customers¡¦ needed. This paper researched the literatures of competitive strategy and advantages, and vertical conformity and division firstly. On the basis of learning industrial structure and specialty, exploring global developing strategy, analyzing up and down panel manufacturer, Wuhan A corporation is selected to be a typical cooperative case, to summarize the result as below. 1. Location selected: As the research result, the location should focus on the value chain building and values add. Also, it needs to think about the possibility of future development. 2. Cost down¡G The cost down policy can be implement in China, because of the lower salary and large number of manpower¡F the abundant nature resources and so on¡C 3. Operation Strategy¡G The strategy need to focus on the core completive advantages, such as flexible, excellent management capability, the ability to build up the marketing channel and so on.