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In order to promote the application and development of civil aviation safety (CAS) in the field of safety and enrich the theoretical system of CAS research, the methodology of CAS was studied. The definition of CAS was reconstructed, its connotation was explained from four aspects, and its research object was clarified. This paper discussed the mechanism of CAS, that is, to maintain system security through the establishment of safety prevention and control system (SPCS), and explained the research content of CAS from theory and technology application. Five principles and applicable methods for CAS research were summarized. In addition, it put forward the general procedure of CAS research, explained the specific content and implementation method or basis of each step. The research results show that the methodology of CAS is a systematic theoretical system with certain guiding significance, combined with the mechanism, research content, research principles and methods, and research procedures of CAS. [ABSTRACT FROM AUTHOR]

A few years ago, a kind of dielectric scanning imaging logging instrument emerged in the foreign markets. That instrument scanned the earth at different frequency electromagnetic wave. It can measure the dielectric constant at different frequencies of the layer. There is not any similar instrument developed at home. Xi'an Shiyou University has launched a project to develop a comparable instrument. This paper introduces the basic principle of dielectric dispersion logging. A general layout is given for the dielectric dispersion logging. The time delay module is simulated and synthesized based on FPGA. This laid the foundation for the development of comparable instruments gradually. [ABSTRACT FROM AUTHOR]

Free-space optical communication receiver aperture is usually a single circular aperture. When the aperture size is large, its cost will be high. This paper proposes a new receiver aperture structure: equidistant dual-aperture receiver. The authors analyze its performance. Aperture Averaging Weight Factors of the two kinds of receiver structures are compared. The analysis results show that: Equidistant dual-aperture receiver can obviously decrease the Aperture Averaging Weight Factor, and reduce the optical scintillation. [ABSTRACT FROM AUTHOR]

Aiming at the operation processes of air traffic control, which analyses unsafe segments existing in the operation of ATC (air traffic control) from more than 60 civil aviation accidents and errors related to controllers, and expresses these unsafe segments from ATC in the form of the event tree, according to the accident case library evaluates severity of various events, and sums up the ATC factors that impact the unsafe segments; then transforms these human factors into Bayesian networks and counts the probability value of human factors through the field survey and statistics, which uses probabilistic safety assessment methods to determine the likelihood of various events; finally, assessment software simple and quickly applied in ATC operation, verified by practical applications, this method improves the efficiency and accuracy of safety assessment, can reach the targeted prevention ATC error, so as to make the right decisions for the operational risk control. [ABSTRACT FROM AUTHOR]

Free-space optical communication is a focus in recent research. Because of the influence of weather conditions, the transmission channel of free-space optical communication dramatically changes. This paper describes the design of a new adaptive rate-controlled optical communication system. The rate adaptively changes through the estimation of the received signal strength. Usually estimate the channel conditions with a low rate of radio frequency feedback. Previously the author used a new technique to design an adaptive rate-controlled optical communication system. It used beacon calibration instead of radio frequency feedback. In this paper an outdoor experiment is performed along a 186 meters horizontal path. On-off Keying modulation is used. The preliminary results with adaptive rate control are compared with that of without adaptive rate control. It appears to be at least an order of magnitude decrease of the bit-error rate. [ABSTRACT FROM AUTHOR]

In this paper, a new kind of method is developed to analyse the bit-error rate for a free-space optical communication system, which is based on the three most important parameters of scintillation statistics, i.e. fraction of time of fade and surge, mean frequency of level crossings, and mean duration of fade and surge. By using this method, the relationship between the bit-error rate and scintillation is clearly identified. The tip-tilt error deteriorates the performance of a free-space optical communication system. Fine tracking ability of adaptive optics (through tip-tilt compensation) can overcome this difficulty. The fade and surge statistical parameters with tip-tilt compensation are evaluated for the plane wave model. The bit-error rate as a function of the scintillation statistical parameters (with tip-tilt compensation) is developed. The results show that the bit-error rate is reduced notably through tip-tilt compensation for free-space optical communication. [ABSTRACT FROM AUTHOR]

Trend technology's theoretical model for atmospheric optical scintillation is establishes in this paper. For many years, people have always thought that atmospheric optics is completely random. In the previous paper, the author has used several experiments to over- turn the traditional view. In this paper, the author will put forward a model to explain the author's point of view theoretically. It will demonstrate the process how does the optical scintillation evolve according to the trend. In this paper, the author will give the second batch of the experimental data to verify the theory model. [ABSTRACT FROM AUTHOR]

Femtosecond frequency comb is a great invention in the field of metrology at the end of the last century. It can simply and effectively synchronize the phases for optical signals of different wavelengths or RF signals. Erbium doped fiber optical comb has many advantages. The National Time Service Center of Chinese Academy of Sciences has launched a project on the new type erbium-doped fiber femtosecond optical comb research. This paper introduces the signal source which is designed for this project. DDS chip AD9854 is used as the signal source. The signal source output has a wideband from 1-80 MHz. Test result for the signal source is discussed. [ABSTRACT FROM AUTHOR]