Ameco-Beijing——a big name in a booming market

Catching up with the fast development of worldeconomy,China pulled up its bamboo curtain andsponsored an even more faster revolution of economytill 1978.The cooperation with German Lufthansa isone of China’s major steps to upgrade its civil avia-tion industry.The Aircraft Maintenance＆EngineeringCo.-Beijing(Ameco-Binjing),a partnership start-ed in 1989 by Air China and German Lufthansa is thelargest and the most powerful civil aircraft mainte-nance company in China.     

Trajectory Tracking Control for a GMM Actuator Based on a Heuristic ILC Method

A heuristic iterative learning control （ILC） method is presented and applied to the trajectory tracking control of a giant magnetostrictive material （GMM） actuator. A GMM actuator is used as experimental equipment for micro-displacement trajectory tracking control. The advantage of the presented approach lies in quitting the model of the GMM actuator. The experimental results attest to the high efficiency of the presented method for the micro-displacement trajectory tracking control.     

Trajectory Tracking Control for a GMM Actuator Based on a Heuristic ILC Method

A heuristic iterative learning control (ILC) method is presented and applied to the trajectory tracking control of a giant magne-tostrictive material (GMM) actuator. A GMM actuator is used as experimental equipment for micro-displacement trajectory tracking control. The advantage of the presented approach lies in quitting the model of the GMM actuator. The experimental results attest to the high efficiency of the presented method for the micro-displacement trajectory tracking control.     

Optimal planning for a multi-debris active removal mission with a partial debris capture strategy

In this paper, a new mission model, called a multi-debris active removal mission with partial debris capture strategy, is proposed. The model assumes that a platform only captures part of the scheduled debris at a time and then releases these debris pieces to a disposal orbit. This process is then repeated until all of the scheduled debris is removed. A genetic algorithm with a multiparameter concatenated coding method is designed to optimize the plan of a multi-debris active removal mission wit...     

Exploration of acceptable operating range for a compression system in a double bypass engine

The variable cycle engine is distinguished by its highly adjustable compression system,whose aerodynamic characteristic is extremely complex. To explore the regulation range of a double bypass engine compression system, a multi-dimensional analysis method is developed, through which the coupling mechanism between the compressor component and the bypass is examined.The operation zones of the compressor components and the bypass system are proposed, and the operation range of the compression syste...     

Investigation of flow unsteadiness in a highly-loaded compressor cascade using a dynamic mode decomposition method

Unsteady flow in the hub endwall region has long been a hot topic in the turbomachinery community. However important it is to the performance of the whole engine, the coherent unsteady flow phenomena are still not well understood. In this paper, the complex flow field in the hub endwall of a cantilevered compressor cascade has been investigated through numerical approach. The predicted results were validated by experimental data. To highlight the dominant flow structures among irregular and chao...     

Aeronautics — a pioneer in European integration

As the first trans-national European industry, aeronautics has been a pioneer in European integration. The European aeronautics business is now a leading player on the world stage contributing to Europe's standing in the global market. Aeronautics creates employment and advances the cutting-edge technology sector in Europe — in education, business and defence matters. Taking its responsibility for the environment seriously, Europe sets the pace for environmental standards in international aeronautics. After all, air travel has become more convenient, practical and affordable — to the benefit of all citizens.     

Innovative design and optimization of a two-dimensional deployable nine-grid planar antenna mechanism with a flat reflection surface

With the development of the aerospace industry, space missions are becoming more complicated and diversified, and there is a demand for antenna mechanisms with a larger physical aperture. In this paper, a planar deployable mechanism is proposed, which can form a flat reflection surface with a small gap between plates. To this end, a novel large-scale two-dimensional deployable nine-grid planar antenna mechanism is designed. First, two antenna folding schemes and four supporting mechanism schemes...     

UJ33a工作电源的改进

UJ33a是测量精度为0.05级的携带式直流电位差计。广泛应用于实验室、车间及现场测量直流电压,亦可经换算后测量直流电阻、电流、功率及温度等。还可作标准电压输出,对电子自动电位差计、毫伏计等以电压作为测量对象的工业仪表进行校验。由于该仪器精度高、便于携带、用途广而颇受欢迎。UJ33a的工作电源为三节1号电池并联为一组,再两组串联为3V,根据设计要求,工作电源的电压允许范围为2.8～3.2V,若电池电压超过这个范围,工作电流就不能调至标准值3mA,这相当于单节电池用到1.4V以下就不能用了。故电池的使用效率较低。另外,由于电池容量有…     

Drawing a Grand Blueprint for the New Century

The 16th National Congress of the Communist Party of China, which has become thefocus of world attention, was successfully held from Nov. 8. As the first national congressof CPC in the new century, this Congress put forward the strategic objectives for Ch…     

Do drones have a realistic place in a pandemic fight for delivering medical supplies in healthcare systems problems?

The advancement of Unmanned Aerial Vehicle (UAV) technology in terms of industrialprocesses and communication and networking technologies has led to an increase...     

梅塞施米特Me 262 A-1a解剖图

梅塞施米特Me 262 A-1a解剖图     

β Cephei stars from a photometric point of view

This is an observational review, with an emphasis on photometric data and their interpretation. Two lists are presented, one containing Cephei stars, and the other, Cephei suspects. These lists then serve as a basis for discussing such topics as the location of Cephei stars in the observational and theoretical H-R diagrams, the evolutionary state of these stars, the period-luminosity and period-luminosity-color relations, and observational identification of pulsation modes. The paper also includes references to recent work connected with the theoretical discovery that an opacity mechanism is responsible for the excitation of Cephei-star pulsations. Finally, observational programs for verifying the consequences of this discovery are suggested.Belgian Fund for Scientific Research (NFWO).     

Experimental investigation of a gliding discharge plasma jet igniter

Relight of jet engines at high altitude is difficult due to the relatively low pressure and temperature of inlet air. The penetration of initial flame kernel affects the ignition probability in the turbine engine combustor greatly. In order to achieve successful ignition at high altitude, a deeper penetration of initial flame kernel should be generated. In this study, a Gliding Arc Plasma Jet Igniter(GAPJI) is designed to induce initial flame kernel with deeper penetration to achieve successful ...     

β Cephei stars from a photometric point of view

This is an observational review, with an emphasis on photometric data and their interpretation. Two lists are presented, one containing β Cephei stars, and the other, β Cephei suspects. These lists then serve as a basis for discussing such topics as the location of β Cephei stars in the observational and theoretical H-R diagrams, the evolutionary state of these stars, the period-luminosity and period-luminosity-color relations, and observational identification of pulsation modes. The paper also includes references to recent work connected with the theoretical discovery that an opacity mechanism is responsible for the excitation of β Cephei-star pulsations. Finally, observational programs for verifying the consequences of this discovery are suggested.     

Joining the World Trade Organization With a Cool Head

On Nov. 11 the Doha meeting completed the formal approval procedures for China to join the WTO, putting a perfect end to the too long wait of the Chinese.15 years have passed since China began its efforts in entering the WTO. China set off on its way to ＂return to the GATT＂ with the development of its reforms in 1986. From that time till its success today, the name of the negotiations changed and the negotiators got old. This process is a memory of vicissitudes.Now the WTO is really …     

Evolution of turbulent boundary layer over a three-dimensional bump

A bump is typically used in the inlet system of an aircraft engine to compress the incoming airflow and to reduce boundary layer thickness developed over fuselage. In this work, the turbulent flow over a three-dimensional bump is experimentally studied. The bump model is mounted in a closed return wind tunnel operated at the nominal velocity 10 m/s, corresponding to a friction Reynolds number of 2300. The flow field upstream the bump, along the bump centerline and at two different spanwise plane...     

同余式 x~p≡a(modp~l)的解法

给出了判别同余式ｘＰ≡ａ（ｍｏｄｐｌ）是否有解的一个充分条件，并给出了它的一个解法