Zhang Zhaoning

Assessment of collision risk on intersecting tracks based on communication navigation surveillance performances

This paper presents a new assessment model for the collision risk of aircraft on intersecting tracks. Focusing on route flight safety, the model is based on the well-established Reich model. Position errors and collision risk of aircraft under communication, navigation, surveillance (CNS) performances were studied. With considering communication, navigation and surveillance errors, Reich model was modified and a computation formula of lateral overlap probability on intersecting tracks was deduced. Hereby, the assessment model of collision risk on intersecting tracks was established. At last, a practical example of assessment of collision risk on intersecting tracks was given. Computation result shows that the flight environment with CNS performance is safe, so the model is feasible.

Power system fault data compression based on wavelet packet transform and vector quantization

According to the characteristics of fault transient signal of a power system, some principles of fault signal compression are proposed. That is keeping some waveband lossless compression and other waveband lossy compression. An integrated signal compression algorithm based on wavelet packet transform, Huffman coding and vector quantization is proposed. Programming software is also given. The simulation result shows this algorithm can precisely meet the requirements of signal compression in a power system and have great application potential.

Notice of Retraction A study of safety sequencing for aviation maintenance multi-index

Based on various factors which influence on aviation maintenance safety, the multi-index system of aviation maintenance safety was constructed and the quantitive rule of the index was ascertained, the synthetical sequencing model of aviation maintenance multi-index safety was established in the employ of principal component analysis method. An example of the safety of 3 units of aviation maintenance were analyzed in the light of the sequencing model, both factors of the index system affected the operation of aviation maintenance safety were found out, namely the violation, the knowledge and skill of maintainers, which was consistent with the importance sequencing of aviation maintenance safety in accident analysis report basically. The computed result of example showed that the method is useful for making the scientific safety measures of aviation maintenance and improving its safety.

Multi-airports ground-holding dynamic model and optimal algorithm basing airports priority

With the rapid increase of the air traffic transportation, the air traffic congest became more and more serious, so to study the flow optimization problem is very importation and urgent. In this paper, a new multi-airports ground-holding dynamic model with en-route capacity constrain has been built, and a heuristic optimal algorithm basing airports priority has been given. The detailed algorithm device thought and process have been present. The algorithm hammers to approval a real-time solution which satisfying all capacity constrains. The simulation results validate the feasibility of the proposed model and algorithm.

Computation of safe separation on cross track

It investigates initially inverse problems of collision risk models, which compute the safe separation through establishing a model under the condition of a given safe target grade. First, improve models of the existed collision risk models on the crossing track, and get across-track computing safe separation improved models. Secondly, establish the same step iterative arithmetic based on the features of improved models, use it to compute separation value of the improved model and the arithmetic is simple and practical for improved model calculations. Lastly, simulate it on two cross route in ShangHai airspace, then compare them to the actual flight separation rules and analyze them after getting results, and give the suggestion on reducing separation.

Applications of fast wavelet transformation algorithm based explicit wavelets in fault detection

For the required frequency information, the Mallat algorithm of wavelet transformation has slower response speed because of repeat use, while the wavelet packets transformation algorithm have a more calculative amount. This paper gives a fast algorithm derived from the definition of continuous wavelet transformation to obtain the required frequency information. The algorithm is good for the calculation on line, so it has much practical meaning for the real time fault detector. When applied to the fault detector during the system swing of HV line protection equipment, the RTDS (real time digital simulation) tests as well as the theoretical results show that the fast algorithm proposed in this paper can satisfy the request of fault detection.

A heuristic dynamic optimal algorithm for the single airport ground-holding problem

A new heuristic optimal algorithm had been present in this paper basing on the real air traffic to solve the single airport ground-holding problem. The dynamic real-time solution can been achieved by segmenting the time, adding the take-off sign, separate calculating ground delay and air delay circulating and refreshing. The paper also gives a simple method to achieve a near solution.