Principles for Optimizing Geometric and Functional Properties of Railway Track Reverse Transitions
Issue:
Volume 7, Issue 5, September 2022
Pages:
74-83
Received:
21 July 2022
Accepted:
24 August 2022
Published:
8 September 2022
DOI:
10.11648/j.ajtte.20220705.11
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Abstract: The article describes the principles of optimizing the railway track alignment design on the example of a transition between reverse curves. The purpose of this optimization was to minimize the length of the reverse transitions of railway track under the condition of ensuring the simplicity of their construction and subsequent operation with a high level of safety and driving comfort. The results obtained show that this goal can be achieved by using consistent forms of inverse transitions with non-identical functions of track axis curvature variation and its cross slope. This is confirmed by comparing the achieved level of their quality with the quality of similar transitions designed using “out-swinging” transition curves. The potential of their advantages is limited by some provisions of the current regulations with formal requirements for the design parameters of the alignment of the railway track. In contrast to this, they should contain requirements for integrative indicators of the ergonomic and technical aspects of the quality of the Track + Rail Car system functioning. They should be calculated taking into account the kinematics of the rail car design points located at levels that are relevant for these aspects. For example, at the level of the highest location of the vestibular apparatus of the passenger and/or the center of mass of the rail car. It is also important to take into account the kinematics of the points of interaction of the coupling devices of the rail cars. The examples of optimization of reverse transitions considered in the article indicate a significant influence of the geometric properties of their shapes on the coordinates, curvature and accelerations at these points. From this it follows that in order to implement the progressive requirements for taking into account their kinematics, the following are necessary: a) criteria for the compliance of its indicators with the conditions of safe and comfortable movement; b) requirements for properties of the curvature and cross slope functions that may be suitable for transitions design; c) criteria for harmonizing these properties in order to achieve the best result under given constraints. The issues considered in this article can serve as a basis for a discussion about the feasibility and effectiveness of implementing these measures for consistent forms of reverse transitions with non-identical variant functions of the track curvature and its cross slope.
Abstract: The article describes the principles of optimizing the railway track alignment design on the example of a transition between reverse curves. The purpose of this optimization was to minimize the length of the reverse transitions of railway track under the condition of ensuring the simplicity of their construction and subsequent operation with a high...
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A Financial Feasibility Study on the New Aircraft Investment Based on Multiple Perspectives -- A Case Study of Boeing 7E7
Mengyuan Lu,
Xiao Zhang,
Tira Zhang
Issue:
Volume 7, Issue 5, September 2022
Pages:
84-92
Received:
12 September 2022
Accepted:
5 October 2022
Published:
11 October 2022
DOI:
10.11648/j.ajtte.20220705.12
Downloads:
Views:
Abstract: Commercial aircraft design and manufacture is known for the characteristics of high investment, high risk and high technology. Typically it is the number one priority to analyze financial feasibility on the manufacturer level to measure future risks and avoid strategic decision-making mistakes. Unlike the fruitful results in the research on technical feasibility of the engine and aircraft body, few studies have been conducted on financial feasibility of new aircraft. This paper formulated a three-step investment feasibility analysis and evaluation method based on multiple perspectives on the manufacturer company level, considering the determination of financial factors, capital structure, sensitivity analysis, economic attractiveness and comparative analysis. Based on the analysis and evaluation theory, this paper took Boeing 7E7 project for instance, demonstrated how a three-step method can be utilized to measure financial feasibility of a new aircraft project. In the first step, the determination of five financial indicators including beta, risk-free rate, market risk premium, cost of equity, cost of debt was illustrated for the project evaluation. In the second step, sensitivity analysis was conducted with @Risk software and comparative study between the financial indicators was clarified. In the third step, economic attractiveness analysis was demonstrated, where macro and micro environment assessment was explained. With the Boeing 7E7 project demonstration, the three-step method was proved to be an effective and applicable method for new aircraft project evaluation. The method proposed in this paper could offer references for general aircraft manufacturers when launching new commercial aircraft like COMAC C919, C929 and other homemade large aircraft.
Abstract: Commercial aircraft design and manufacture is known for the characteristics of high investment, high risk and high technology. Typically it is the number one priority to analyze financial feasibility on the manufacturer level to measure future risks and avoid strategic decision-making mistakes. Unlike the fruitful results in the research on technic...
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