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THE Rainbow is the commercial adaptation of the XF‐12 photographic aeroplane the Republic Aviation Corporation completed for the Army Air Forces. In 1943, the Photographic…
THE Rainbow is the commercial adaptation of the XF‐12 photographic aeroplane the Republic Aviation Corporation completed for the Army Air Forces. In 1943, the Photographic Section of the A.A.F. issued specifications for a new multi‐engined, long‐range, high‐speed, reconnaissance aeroplane to fly at very high altitudes. The required performance was so much beyond anything in existence at the time that it posed a real problem to designers of high performance aeroplanes. Republic engineers, who for years had specialized in high‐altitude, high‐speed pursuit planes, eagerly accepted the challenge. After exhaustive studies it was found that the performance required by the specification could only be met with a four‐engined machine using Pratt and Whitney R‐4360 engines, supercharged to carry full military power to 40,000 ft. Other combinations would either fail in speed, or in range, or in desired rate of climb or ceiling. A proposal based on four 4360 engines was submitted to the A.A.F., and in March 1944, the Company was awarded a contract for two XF‐12 aircraft. The first prototype was completed in December, 1945, and made its first flight on February 4, 1946.
A transport innovation has been examined through canvassing opinion from a large sample of long distance travellers. The findings proved that there was no evidence to…
A transport innovation has been examined through canvassing opinion from a large sample of long distance travellers. The findings proved that there was no evidence to support adopter categories in respect of the high speed train. Respondents rated the attribute “relative advantage” as being extremely relevant, whilst “trialability”, “compatibility”, “observability” and “complexity” were not particularly relevant.
The operation safety of the high-speed railway has been widely concerned. Due to the joint influence of the environment, equipment, personnel and other factors, accidents…
The operation safety of the high-speed railway has been widely concerned. Due to the joint influence of the environment, equipment, personnel and other factors, accidents are inevitable in the operation process. However, few studies focused on identifying contributing factors affecting the severity of high-speed railway accidents because of the difficulty in obtaining field data. This study aims to investigate the impact factors affecting the severity of the general high-speed railway.
A total of 14 potential factors were examined from 475 data. The severity level is categorized into four levels by delay time and the number of subsequent trains that are affected by the accident. The partial proportional odds model was constructed to relax the constraint of the parallel line assumption.
The results show that 10 factors are found to significantly affect accident severity. Moreover, the factors including automation train protection (ATP) system fault, platform screen door and train door fault, traction converter fault and railway clearance intrusion by objects have an effect on reducing the severity level. On the contrary, the accidents caused by objects hanging on the catenary, pantograph fault, passenger misconducting or sudden illness, personnel intrusion of railway clearance, driving on heavy rain or snow and train collision against objects tend to be more severe.
The research results are very useful for mitigating the consequences of high-speed rail accidents.
The causes of high-speed railway failures are complex, and it is difficult to quantitatively and accurately describe safety evaluation. The purpose of this paper is to…
The causes of high-speed railway failures are complex, and it is difficult to quantitatively and accurately describe safety evaluation. The purpose of this paper is to construct a model to ensure the safety of high-speed railway operations.
The authors construct a high-speed railway operation safety evaluation index system from four aspects: personnel, equipment, environment and management and analyze the inter-coupling relationship of various safety factors. Based on the evaluation index system, the use of network analytic hierarchy process (ANP) and fuzzy comprehensive evaluation will be used to establish a high-speed railway operation safety evaluation model.
Through the literature investigation and field investigation, combined with high-speed railway safety key points and system composition, 4 first-level indicators and 17 second-level indicators were selected to construct a high-speed railway operation safety evaluation index system. It can be seen from the results that the personnel management system and the signal and control system have the largest weight.
On the basis of establishing an evaluation index system, comprehensively considering the internal coupling relationship between evaluation indexes and the fuzziness of high-speed railway operation safety evaluation, high-speed railway uses ANP fuzzy network analysis method to construct high-speed railway operation, and the safety evaluation model has certain advantages and practicability in the case of the relative lack of high-speed railway operation data and fault data.
The breakdown of laminar flow in the clearance space of a journal is considered, and the point of transition is considered in relation to experiments carried out with ‘bearings’ of large clearance. Experiments involving flow visualization with very large clearance ratios of 0.05 to 0.3 show that the laminar regime gives way to cellular or ring vertices at the critical Reynolds number predicted by G. I. Taylor for concentric cylinders even in the presence of an axial flow and at a rather higher Reynolds number in the case of eccentric cylinders. The effect of the transition on the axial flow between the cylinders is small. The critical speed for transition as deduced by Taylor, is little affected by moderate axial flows and is increased by eccentricity. The effect of critical condition on the axial‐flow characteristics of the bearing system appears to be negligible, again for moderate axial flows. Assuming that the results can be extrapolated to clearances applicable to bearing operation, the main conclusion of this paper is that the breakdown of laminar flow, which is a practical possibility in very high‐speed bearings, is delayed by eccentric operation.
The high-speed rail network can lead to the transformation of the tourism industry, as well as the regional economy. In the present study, a reasonable method was…
The high-speed rail network can lead to the transformation of the tourism industry, as well as the regional economy. In the present study, a reasonable method was developed to assess the contributions of high-speed rail network to the development of tourism and economy in a Chinese region known as the “1 + 8” city tourism circle.
The method proposed here combines not only tourism revenue but also regional economy in a MGM (1, n) gray model, and it studies the tourist and economic output of this tourism circle before and after the high-speed rail network’s construction using an advanced “with and without comparison” method.
By using this method, the accuracy of the prediction of the contribution rate of high-speed rail network is improved. We found that in the “1 + 8” city tourism circle, the high-speed rail network positively contributes to increase of the tourism arrival and tourism revenue. Furthermore, regional economy significantly grows under the impact of the high-speed rail network.
The “1 + 8” city tourism circle is studied as a closed system in this paper, and the authors focus on the economic associations between the cities in the circle by ignoring the impact from outside this circle. This treatment means, simplifies and enables the feasibility of this study, but it virtually leads to the deviation of outcomes between this study and the practical.
For theoretical values, by studying a normal Chinese inland region, this study reconfirmed the positive impact of high-speed railway empirically. In the meantime, this study developed an improved method by introducing gray theory models to “with and without comparison” method to calculate the contribution of high-speed railway to the regional tourism and economy development. Such method simultaneously incorporates the indexes of regional tourism income and regional GDP simultaneously. It is direct and convenient as it can achieve accuracy requirements using only a small amount of data, and it reconciles more with reality by considering the interaction of the outcomes of tourism and economy.
For practical values, using the proposed method, a direct and convenient calculation of the contributions of high-speed railway to many other regions can be achieved if the data of the outcomes of tourism and economy can be obtained. In such a way, the regions that really need high-speed railway to stimulate their development can be distinguished from regions whose high-speed railway is under blind construction. Thus, the government may take actions to reassess some uneconomic high-speed railway projects without discouraging the construction of high-speed railway in other regions. The authors believe that this is important not only for China but also for many other countries with high-speed railway projects.
This study develops a reasonable method of assessing the contribution of high-speed rail to regional tourism and economic development. Using this method, this study confirmed that high-speed rail indeed positively impacts the regional development.
高速铁路（HSR）网络可以带动旅游业乃至区域经济的转型。本研究构建了一个合理的方法来评估高铁网络对中国 “1+8” 城市旅游圈的旅游产业和区域经济发展的贡献。
本文提出的方法将旅游收入和区域经济的指标结合在一个MGM（1，n）灰色模型中，并采用先进的 “有无比较法” 来研究高铁网建设前后该旅游圈的旅游和经济产出。
本文将 “1+8” 城市旅游圈作为一个封闭的系统进行研究，忽略了外部因素的影响，而重点研究旅游圈内城市之间的经济联系。这种处理方法简化了本研究的过程，增加了研究的可行性，但实际上导致了本研究结果与现实存在偏差。
La red de ferrocarril de alta velocidad (HSR) puede liderar la transformación de la industria turística, así como la economía regional. En el presente estudio, se ha desarrollado un método para evaluar las contribuciones de la red ferroviaria de alta velocidad, en el desarrollo económico en una región China conocida como el círculo de turismo urbano “1+8”.
El método que se propone combina, no solamente los ingresos por turismo, sino también la economía regional en un modelo MGM (1,n) gris, y estudia la producción turística y económica de este círculo turístico, antes y después de las construcción de la red ferroviaria de alta velocidad utilizando un método “con y sin comparación”.
Usando este método, se mejora la predicción de la tasa de contribución de la red de alta velocidad. Nosotros descubrimos que en el círculo “1+8”, la red ferroviaria de alta velocidad contribuye positivamente al aumento en la llegadas de turistas y los ingresos por turismo. Además, la economía regional, crece significativamente bajo el impacto de esta red.
Limitaciones de la investigación/implicaciones
En este artículo, el círculo de turismo urbano “1+8”, se estudia como un sistema cerrado, se enfoca en la asociación económica entre las ciudades, pero ignorando el impacto desde fuera. Este tratamiento significa simplificar y habilitar la viabilidad de este estudio, pero prácticamente conduce a la desviación de los resultados entre este estudio y la practica.
El valor teórico, estudiando una región normal del interior de China, reconfirma el impacto positivo del ferrocarril de alta velocidad. Mientras tanto, este estudio desarrolla un método mejorado, introduciendo los modelos de “teoría gris” en los métodos “con y sin comparación”, para el calculo de la contribución del ferrocarril de alta velocidad en el desarrollo de la economía regional y turística. Además y simultáneamente, el método incorpora los índices de ingresos del turismo regional y el PIB. Esto es directo y conveniente, ya que puede cumplir con los requisitos de precisión, usando solamente una pequeña cantidad de datos, y concilia más con la realidad considerando la interacción del resultado del turismo y economía.
Para los valores prácticos, usando el modelo propuesto, se puede lograr un cálculo directo y conveniente de las contribuciones del ferrocarril de alta velocidad a muchas otras regiones, y se pueden obtener datos del impacto del turismo y la economía. De esta manera, las regiones que realmente necesiten el ferrocarril de alta velocidad para estimular su desarrollo, se podrán diferenciar de aquellas otras que lo planteen a ciegas. Por lo tanto, los gobiernos deberían tomar acciones para reevaluar algunos proyectos ferroviarios de alta velocidad ineficientes, sin desalentar la construcción de los mismos en otras regiones. Los autores creen que esto no sólo es importante para China, sino también para muchos otros países con proyectos de ferrocarriles de alta velocidad.
Este estudio desarrolla un método razonable de evaluación de la contribución del ferrocarril de alta velocidad, en el desarrollo de la economías regionales y turísticas. Usando este método, este estudio confirma que el ferrocarril de alta velocidad añade impactos positivos en el desarrollo regional.
The purpose of this paper is to design an oil-air lubrication system with low temperature rise, vibration and noise simplifies the spindle configuration. The oil-air…
The purpose of this paper is to design an oil-air lubrication system with low temperature rise, vibration and noise simplifies the spindle configuration. The oil-air lubrication unit is a key component for high-speed grinding machine tools. The development of oil-air lubrication unit suitable for high/ultrahigh rotational speed is a daunting task owing to the lubrication challenges.
This paper emphasizes three main issues: the analysis of oil-air two-phase flow for tradition oil-air lubrication unit with the simulation method; the design of new oil-air lubrication unit for the high/ultrahigh-speed grinding machine tools and the comparative experiment research of tradition and new oil-air lubrication unit. The optimum structure parameters that create the optimum flow pattern and operating conditions resulting in low temperature increase, vibration and noise of oil-air lubricated spindle can be achieved by the simulation method and experiments.
The simulation and experimental results show that new oil-air lubrication unit lubricating a high speed electric spindle has a better performance with a small temperature increase and vibration, which means that our proposed method is an effective design method for oil-air lubrication system.
A design method suitable for high-speed oil-air lubrication unit is proposed. New oil-air lubrication unit is expected to apply for high/ultrahigh rotational speed grinding machine tools.
EACH September the eyes of the aeronautical World turn towards the S.B.A.C. Air Display and Exhibition with interest unequalled by any other event. It is fitting that the…
EACH September the eyes of the aeronautical World turn towards the S.B.A.C. Air Display and Exhibition with interest unequalled by any other event. It is fitting that the Display is now held each year at the airfield of the Royal Aircraft Establishment, one of the world's most prominent aeronautical research centres. This interest becomes increasingly keen too, as the preview day comes closer, because new prototypes of unorthodox designs often appear a short time before the Show to illustrate the results of years of careful planning, development and research of the particular company. These designs often mould the path of progress for smaller countries without the economic resources to forge the way ahead alone. Most British citizens are very proud of their country's place in aviation today, both in the military and civil fields. This is understood by most foreigners because it is clear that Britain has won a place in aeronautical development second to none.