The basic concepts and advantages of more/all electric aircraft （M/AEA） are briefly addressed. The combined starter/generator （CS/G） system is introduced as a key technology to enable M/AEA. Some important perform...The basic concepts and advantages of more/all electric aircraft （M/AEA） are briefly addressed. The combined starter/generator （CS/G） system is introduced as a key technology to enable M/AEA. Some important performance requirements for CS/G system are obtained. Based on these requirements, a high speed switched reluctance machine （SRM） is designed to operate as a starter/generator. The entire design process is mainly divided into two stages： electromagnetic design and thermal design. In electromagnetic design stage, the electromagnetic structure and dimensions of the machine and the number of phase winding turns per pole are obtained; the topology and main technical details of the converter are briefly introduced as well. In thermal design stage, a liquid-cooling system is designed based on the thermal analysis of the machine. In the end, the performances of the designed SRM are basically verified by simulation. To get high performances, the exciting angles are optimized in two different operating modes respectively, and the optimized performances in the motoring mode are given as well.展开更多
本研究根据Michael Hoey提出的词汇触发理论,分别考察了英文短语"more and more"在香港理工大学汉英当代文本平行语料库(PCCE)、英国国家语料库(BNC)和中国英语学习者语料库(CLEC)中的频率、类连接形式与搭配形式。研究发现,...本研究根据Michael Hoey提出的词汇触发理论,分别考察了英文短语"more and more"在香港理工大学汉英当代文本平行语料库(PCCE)、英国国家语料库(BNC)和中国英语学习者语料库(CLEC)中的频率、类连接形式与搭配形式。研究发现,母语环境和非母语环境、双语转换环境和语言直接使用环境下的"more and more"触发模式均有各自的特征,源语文本和母语迁移对触发亦有明显的影响作用。本文认为,词汇触发理论能让我们从心理学的角度,重新审视翻译中原文与译文的"对等"关系问题,揭示出某些中、英文词汇即便是语义上完全对等,但由于文化差异等原因,经它们触发的在原文和译文句子中的位置、搭配、语用联想等方面却未必完全一样。这正是原文与译文在行文及风格上不一致的深层原因。因此,词汇触发理论不仅对英汉翻译具有实际指导意义,还提供了英汉对比研究的理论新视角,值得我们重视。展开更多
"翻转课堂"即转变传统的教师统一授课,学生课后复习提高的教学结构,通过对教学模式的颠倒安排,课前有效监管和指导在线听说学习结合课上有目的小班面授,实现课程真正地个性化教学。TMM课程体系的混元英语教学模式是大学英语..."翻转课堂"即转变传统的教师统一授课,学生课后复习提高的教学结构,通过对教学模式的颠倒安排,课前有效监管和指导在线听说学习结合课上有目的小班面授,实现课程真正地个性化教学。TMM课程体系的混元英语教学模式是大学英语听说课程改革的新模式,而TMM教学体系下大学英语听说课程评估的实施是成功实施此模式的关键。该研究通过Tell Me More课程口语评估体系的建立,分析其对学生以语言智能为主的多种学习智能发展的影响,为高等院校大学英语听说教学改革拓展了一个崭新的思路。展开更多
The optional types of power source and actuator in the aircraft are more and more diverse due to fast development in more electric technology, which makes the combinations of different power sources and actuators beco...The optional types of power source and actuator in the aircraft are more and more diverse due to fast development in more electric technology, which makes the combinations of different power sources and actuators become extremely complex in the architecture optimization process of airborne actuation system. The traditional ＂trial and error＂ method cannot satisfy the design demands. In this paper, firstly, the composition of more electric aircraft （MEA） flight control actuation system （FCAS） is introduced, and the possible architecture quantity is calculated. Secondly, the evaluation criteria of FCAS architecture with respect to safe reliability, weight and efficiency are proposed, and the evaluation criteria values are calculated in the case that each control surface adopts the same actuator configuration. Finally, the optimization results of MEA FCAS architecture are obtained by applying genetic algorithm （GA）. Compared to the traditional actuation system architecture, which only adopts servo valve controlled hydraulic actuators, the weight of the optimized more electric actuation system architecture can be reduced by 6%, and the efficiency can be improved by 30% based on the safe reliability requirements.展开更多
Electromechanical actuators（EMAs） are becoming increasingly attractive in the field of more electric aircraft because of their outstanding benefits, which include reduced fuel burn and maintenance cost, enhanced sys...Electromechanical actuators（EMAs） are becoming increasingly attractive in the field of more electric aircraft because of their outstanding benefits, which include reduced fuel burn and maintenance cost, enhanced system flexibility, and improved management of fault detection and isolation. However, electromechanical actuation raises specific issues when being used for safetycritical aerospace applications like flight controls： huge reflected inertia to load, jamming-type failure, and increase of backlash with service due to wear and local dissipation of heat losses for thermal balance. This study proposes an incremental approach for virtual prototyping of EMAs. It is driven by a model-based system engineering process in order to enable simulation-aided design.Best practices supported by Bond graph formalism are suggested to develop a model＇s structure efficiently and to make the model ready for use（or extension） by addressing the above mentioned issues. Physical effects are progressively introduced, and the realism of lumped-parameter models is increased step-by-step. In particular, multi-level component models are architected to ensure continuity between engineering activities. The models are implemented in the AMESim simulation environment, and simulation responses are given to illustrate how they can be used for preliminary sizing, control design, thermal balance verification, and faults to failure analysis. The proposed best practices intend to provide engineers with fast, reusable, and efficient means to assess performance virtually and enhance maturity, performance, and robustness.展开更多
Traditional hydraulic brake systems require a complex system of pipelines between an aircraft engine driven pump（EDP） and brake actuators, which increases the weight of the aircraft and may even cause serious vibrat...Traditional hydraulic brake systems require a complex system of pipelines between an aircraft engine driven pump（EDP） and brake actuators, which increases the weight of the aircraft and may even cause serious vibration and leakage problems. In order to improve the reliability and safety of more electric aircraft（MEA）, this paper proposes a new integrated self-powered brake system（ISBS） for MEA. It uses a hydraulic pump geared to the main wheel to recover a small part of the kinetic energy of a landing aircraft. The recovered energy then serves as the hydraulic power supply for brake actuators. It does not require additional hydraulic source, thus removing the pipelines between an EDP and brake actuators. In addition, its self-powered characteristic makes it possible to brake as usual even in an emergency situation when the airborne power is lost. This paper introduces the working principle of the ISBS and presents a prototype. The mathematical models of a taxiing aircraft and the ISBS are established. A feedback linearization control algorithm is designed to fulfill the anti-skid control. Simulations are carried out to verify the feasibility of the ISBS, and experiments are conducted on a ground inertia brake test bench. The ISBS presents a good performance and provides a new potential solution in the field of brake systems for MEA.展开更多
On Aug.8, 2017, an M_S 7.0 earthquake struck Jiuzhaigou, a county of Sichuan province, China. A number of investigations and studies have been conducted, some of which involved local velocity models. However, the suit...On Aug.8, 2017, an M_S 7.0 earthquake struck Jiuzhaigou, a county of Sichuan province, China. A number of investigations and studies have been conducted, some of which involved local velocity models. However, the suitability of these models has not been properly addressed. Here we collect 11 already-existing models, including those used in studies of the 2017 M_S 7.0 Jiuzhaigou earthquake,choose 10 local stations surrounding the earthquake, and employ the same technique(TRIT) to relocate the hypocenter. And furthermore, we choose a more suitable model from the 11 already-existed models by analyzing the relocation process and the relocated results for reasonability. Finally, our conclusion is that the model Fang 2018 is more suitable and the hypocenter parameters, 103.801°E,33.192°N and 15.8 km for longitude, latitude and depth, respectively, and 2017-08-08 13:19:46.66 for its origin time, based on this model should be recommended for the 2017 M_S7.0 Jiuzhaigou earthquake.展开更多
The huge and rapid progress in electric drives offers new opportunities to improve the performances of aircraft at all levels：fuel burn,environmental footprint,safety,integration and production,serviceability,and mai...The huge and rapid progress in electric drives offers new opportunities to improve the performances of aircraft at all levels：fuel burn,environmental footprint,safety,integration and production,serviceability,and maintainability.Actuation for safety-critical applications like flight-controls,landing gears,and even engines is one of the major consumers of non-propulsive power.Conventional actuation with centralized hydraulic power generation and distribution and control of power by throttling has been well established for decades,but offers a limited potential of evolution.In this context,electric drives become more and more attractive to remove the natural drawbacks of conventional actuation and to offer new opportunities for improving performance.This paper takes the stock,at both the signal and power levels,of the evolution of actuation for safety-critical applications in aerospace.It focuses on the recent advances and the remaining challenges to be taken toward full electrical actuation for commercial and military aircraft,helicopters,and launchers.It logically starts by emphasizing the specificity of safety-critical actuation for aerospace.The following section addresses in details the evolution of aerospace actuation from mechanically-signaled and hydraulically-supplied to all electric,with special emphasis on research and development programs and on solutions entered into service.Finally,the last section reviews the challenges to be taken to generalize the use of all-electric actuators for future aircraft programs.展开更多
"Iess is more"是20世纪20年代密斯·凡·德·罗提出的一项经典建筑设计法则。该法则对同时代乃至随后的几代建筑师都产生了深刻的影响。在西方近现代建筑发展史上该法则曾倍受推崇,也饱受诟病。在密斯本人逝世4..."Iess is more"是20世纪20年代密斯·凡·德·罗提出的一项经典建筑设计法则。该法则对同时代乃至随后的几代建筑师都产生了深刻的影响。在西方近现代建筑发展史上该法则曾倍受推崇,也饱受诟病。在密斯本人逝世40周年之际,本文简要回顾了该法则产生的时代背景,并对其在不同时代所产生的影响进行了分析和阐述,最终致力于提出在可持续发展的社会大背景下,该法则对现代建筑设计仍然具有极其深刻的借鉴意义和推广价值。展开更多
The Auto-Transformer Rectifier Unit（ATRU） is one preferred solution for high-power AC/DC power conversion in aircraft. This is mainly due to its simple structure, high reliability and reduced k VA ratings. Indeed, t...The Auto-Transformer Rectifier Unit（ATRU） is one preferred solution for high-power AC/DC power conversion in aircraft. This is mainly due to its simple structure, high reliability and reduced k VA ratings. Indeed, the ATRU has become a preferred AC/DC solution to supply power to the electric environment control system on-board future aircraft. In this paper, a general modelling method for ATRUs is introduced. The developed model is based on the fact that the DC voltage and current are strongly related to the voltage and current vectors at the AC terminals of ATRUs. In this paper, we carry on our research in modelling symmetric 18-pulse ATRUs and develop a generic modelling technique. The developed generic model can study not only symmetric but also asymmetric ATRUs. An 18-pulse asymmetric ATRU is used to demonstrate the accuracy and efficiency of the developed model by comparing with corresponding detailed switching SABER models provided by our industrial partner. The functional models also allow accelerated and accurate simulations and thus enable whole-scale more-electric aircraft electrical power system studies in the future.展开更多
文摘The basic concepts and advantages of more/all electric aircraft （M/AEA） are briefly addressed. The combined starter/generator （CS/G） system is introduced as a key technology to enable M/AEA. Some important performance requirements for CS/G system are obtained. Based on these requirements, a high speed switched reluctance machine （SRM） is designed to operate as a starter/generator. The entire design process is mainly divided into two stages： electromagnetic design and thermal design. In electromagnetic design stage, the electromagnetic structure and dimensions of the machine and the number of phase winding turns per pole are obtained; the topology and main technical details of the converter are briefly introduced as well. In thermal design stage, a liquid-cooling system is designed based on the thermal analysis of the machine. In the end, the performances of the designed SRM are basically verified by simulation. To get high performances, the exciting angles are optimized in two different operating modes respectively, and the optimized performances in the motoring mode are given as well.
基金ESRC/RGC Joint Research Scheme项目"Comparable and Parallel Corpus Approaches to the Third Code:English and Chinese Perspectives"(项目编号:RGC/Gov No.:ES/K010107/13-ZG2G)支持
文摘本研究根据Michael Hoey提出的词汇触发理论,分别考察了英文短语"more and more"在香港理工大学汉英当代文本平行语料库(PCCE)、英国国家语料库(BNC)和中国英语学习者语料库(CLEC)中的频率、类连接形式与搭配形式。研究发现,母语环境和非母语环境、双语转换环境和语言直接使用环境下的"more and more"触发模式均有各自的特征,源语文本和母语迁移对触发亦有明显的影响作用。本文认为,词汇触发理论能让我们从心理学的角度,重新审视翻译中原文与译文的"对等"关系问题,揭示出某些中、英文词汇即便是语义上完全对等,但由于文化差异等原因,经它们触发的在原文和译文句子中的位置、搭配、语用联想等方面却未必完全一样。这正是原文与译文在行文及风格上不一致的深层原因。因此,词汇触发理论不仅对英汉翻译具有实际指导意义,还提供了英汉对比研究的理论新视角,值得我们重视。
文摘"翻转课堂"即转变传统的教师统一授课,学生课后复习提高的教学结构,通过对教学模式的颠倒安排,课前有效监管和指导在线听说学习结合课上有目的小班面授,实现课程真正地个性化教学。TMM课程体系的混元英语教学模式是大学英语听说课程改革的新模式,而TMM教学体系下大学英语听说课程评估的实施是成功实施此模式的关键。该研究通过Tell Me More课程口语评估体系的建立,分析其对学生以语言智能为主的多种学习智能发展的影响,为高等院校大学英语听说教学改革拓展了一个崭新的思路。
基金National Natural Science Foundation of China （50675009） International Science ＆ Technology Cooperation Program of China （2010DFA72540）
文摘The optional types of power source and actuator in the aircraft are more and more diverse due to fast development in more electric technology, which makes the combinations of different power sources and actuators become extremely complex in the architecture optimization process of airborne actuation system. The traditional ＂trial and error＂ method cannot satisfy the design demands. In this paper, firstly, the composition of more electric aircraft （MEA） flight control actuation system （FCAS） is introduced, and the possible architecture quantity is calculated. Secondly, the evaluation criteria of FCAS architecture with respect to safe reliability, weight and efficiency are proposed, and the evaluation criteria values are calculated in the case that each control surface adopts the same actuator configuration. Finally, the optimization results of MEA FCAS architecture are obtained by applying genetic algorithm （GA）. Compared to the traditional actuation system architecture, which only adopts servo valve controlled hydraulic actuators, the weight of the optimized more electric actuation system architecture can be reduced by 6%, and the efficiency can be improved by 30% based on the safe reliability requirements.
基金supports of the China Scholarship Council(CSC)the National Natural Science Foundation of China(No.51275021 and No.61327807)
文摘Electromechanical actuators（EMAs） are becoming increasingly attractive in the field of more electric aircraft because of their outstanding benefits, which include reduced fuel burn and maintenance cost, enhanced system flexibility, and improved management of fault detection and isolation. However, electromechanical actuation raises specific issues when being used for safetycritical aerospace applications like flight controls： huge reflected inertia to load, jamming-type failure, and increase of backlash with service due to wear and local dissipation of heat losses for thermal balance. This study proposes an incremental approach for virtual prototyping of EMAs. It is driven by a model-based system engineering process in order to enable simulation-aided design.Best practices supported by Bond graph formalism are suggested to develop a model＇s structure efficiently and to make the model ready for use（or extension） by addressing the above mentioned issues. Physical effects are progressively introduced, and the realism of lumped-parameter models is increased step-by-step. In particular, multi-level component models are architected to ensure continuity between engineering activities. The models are implemented in the AMESim simulation environment, and simulation responses are given to illustrate how they can be used for preliminary sizing, control design, thermal balance verification, and faults to failure analysis. The proposed best practices intend to provide engineers with fast, reusable, and efficient means to assess performance virtually and enhance maturity, performance, and robustness.
基金supports from the Science and Technology on Aircraft Control Laboratory and Aviation Key Laboratory of Scienceco-supported by the National Natural Science Foundation of China(No.51475020)the National Key Basic Research Program of China(No.2014CB046401)
文摘Traditional hydraulic brake systems require a complex system of pipelines between an aircraft engine driven pump（EDP） and brake actuators, which increases the weight of the aircraft and may even cause serious vibration and leakage problems. In order to improve the reliability and safety of more electric aircraft（MEA）, this paper proposes a new integrated self-powered brake system（ISBS） for MEA. It uses a hydraulic pump geared to the main wheel to recover a small part of the kinetic energy of a landing aircraft. The recovered energy then serves as the hydraulic power supply for brake actuators. It does not require additional hydraulic source, thus removing the pipelines between an EDP and brake actuators. In addition, its self-powered characteristic makes it possible to brake as usual even in an emergency situation when the airborne power is lost. This paper introduces the working principle of the ISBS and presents a prototype. The mathematical models of a taxiing aircraft and the ISBS are established. A feedback linearization control algorithm is designed to fulfill the anti-skid control. Simulations are carried out to verify the feasibility of the ISBS, and experiments are conducted on a ground inertia brake test bench. The ISBS presents a good performance and provides a new potential solution in the field of brake systems for MEA.
基金supported by the DQJB project (DQJB16B05) of the Institute of Geophysics,CEAthe NSFC project (41474046)
文摘On Aug.8, 2017, an M_S 7.0 earthquake struck Jiuzhaigou, a county of Sichuan province, China. A number of investigations and studies have been conducted, some of which involved local velocity models. However, the suitability of these models has not been properly addressed. Here we collect 11 already-existing models, including those used in studies of the 2017 M_S 7.0 Jiuzhaigou earthquake,choose 10 local stations surrounding the earthquake, and employ the same technique(TRIT) to relocate the hypocenter. And furthermore, we choose a more suitable model from the 11 already-existed models by analyzing the relocation process and the relocated results for reasonability. Finally, our conclusion is that the model Fang 2018 is more suitable and the hypocenter parameters, 103.801°E,33.192°N and 15.8 km for longitude, latitude and depth, respectively, and 2017-08-08 13:19:46.66 for its origin time, based on this model should be recommended for the 2017 M_S7.0 Jiuzhaigou earthquake.
文摘The huge and rapid progress in electric drives offers new opportunities to improve the performances of aircraft at all levels：fuel burn,environmental footprint,safety,integration and production,serviceability,and maintainability.Actuation for safety-critical applications like flight-controls,landing gears,and even engines is one of the major consumers of non-propulsive power.Conventional actuation with centralized hydraulic power generation and distribution and control of power by throttling has been well established for decades,but offers a limited potential of evolution.In this context,electric drives become more and more attractive to remove the natural drawbacks of conventional actuation and to offer new opportunities for improving performance.This paper takes the stock,at both the signal and power levels,of the evolution of actuation for safety-critical applications in aerospace.It focuses on the recent advances and the remaining challenges to be taken toward full electrical actuation for commercial and military aircraft,helicopters,and launchers.It logically starts by emphasizing the specificity of safety-critical actuation for aerospace.The following section addresses in details the evolution of aerospace actuation from mechanically-signaled and hydraulically-supplied to all electric,with special emphasis on research and development programs and on solutions entered into service.Finally,the last section reviews the challenges to be taken to generalize the use of all-electric actuators for future aircraft programs.
文摘"Iess is more"是20世纪20年代密斯·凡·德·罗提出的一项经典建筑设计法则。该法则对同时代乃至随后的几代建筑师都产生了深刻的影响。在西方近现代建筑发展史上该法则曾倍受推崇,也饱受诟病。在密斯本人逝世40周年之际,本文简要回顾了该法则产生的时代背景,并对其在不同时代所产生的影响进行了分析和阐述,最终致力于提出在可持续发展的社会大背景下,该法则对现代建筑设计仍然具有极其深刻的借鉴意义和推广价值。
文摘The Auto-Transformer Rectifier Unit（ATRU） is one preferred solution for high-power AC/DC power conversion in aircraft. This is mainly due to its simple structure, high reliability and reduced k VA ratings. Indeed, the ATRU has become a preferred AC/DC solution to supply power to the electric environment control system on-board future aircraft. In this paper, a general modelling method for ATRUs is introduced. The developed model is based on the fact that the DC voltage and current are strongly related to the voltage and current vectors at the AC terminals of ATRUs. In this paper, we carry on our research in modelling symmetric 18-pulse ATRUs and develop a generic modelling technique. The developed generic model can study not only symmetric but also asymmetric ATRUs. An 18-pulse asymmetric ATRU is used to demonstrate the accuracy and efficiency of the developed model by comparing with corresponding detailed switching SABER models provided by our industrial partner. The functional models also allow accelerated and accurate simulations and thus enable whole-scale more-electric aircraft electrical power system studies in the future.
