PSR B0919+06 generally radiates radio pulses in a normal phase range. It has been known for its occasional perplexing abnormal emission events wherein individual pulses come to an earlier phase range for a few tens of periods and then returns to its usual phase. Heretofore, only a few such events have been available for study. We observed PSR B0919+06 for about 30 hours using the Jiamusi 66-m telescope at Jiamusi Deep Space Station at S-band, and detected 92 abnormal emission events. We identify four types of events based on the abrupted or gradual phase-shifting of individual pulses. The abnormal emission events are seen to occur randomly some every 1000 to 3000 periods, and they affect the leading edge of the mean profile by up to 2\% in amplitude. The abnormal emission events are probably related to gradual changes of emission processing in the pulsar magnetosphere.

Pointing accuracy is one of the most important characteristics for a large radio telescope;it is very fundamental for telescope running. To ensure good performance for measuring the flux density of a radio source, pointing accuracy must be kept within 10% of telescope beam size. In this paper we present results of large measurements of telescope points for Jiamusi 66m radio telescope, and show the basic-parameter model and the fitting residuals of pointing data. We find that even after the correction of a new best-fitting basic-parameter model, the pointing uncertainty data still have a systematic variations of concentration along with the azimuth and elevation, which we believe is caused by the high order variations of the angle between the azimuth axis and elevation axis as well as the gravity deformation. We improve the basic-parameter model for the pointing corrections, and we get much improved pointing accuracy for Jiamusi 66m radio telescope from 45″to less than 20″.

Applying real code genetic algorithm and finite difference method,a simple numerical method to approximate the solution of second-order boundary value problem is presented.This method is suit for linear and nonlinear problems.The analysis and numerical results show the efectivity of the method.

This paper represents a method for solving systems of nonlinear equations.Firstly,we transform them into numeric problems of least square approximation.Then,we give some operators of selection,crossover and mutation;we also give strategies of the best individual reservation for convergence speedup,and operators of depopulation and emigration for preventing prematurity.By applying real code genetic algorithm we solved the problem.The results of numerical simulation show the efficiency of the method.

The cause of amplitude and phase imbalances in sum and difference channels, amplitude and phase imbalances influences over angle measurement accuracy are analyzed. A method of digital calibration in the amplitude and phase imbalances of sum and difference channels, and of angle error normalization processing is provided.