ON MIN＇S ZETA-FUNCTION AND HERMITE ELLIPTIC OPERATOR

In this note, the authors study some fundamental properties on a Min＇s zeta- function and explore its connection with Hermite elliptic operator.     

A separation form of unified convergence theorem

In this paper, by introducing isometrically Pc0 property a separation form of convergence theorem is presented and the results generalize and unify several interesting conclusions in recent years.     

8种苯并［h］喹啉的13C NMR归属

报道了8种新的苯并［h］喹啉的     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

对中等学校物理教师自修物理的一点意见

自从党中央央出向科学进军的号召以来,本刊陆续接到许多读者来信,询问有关进修高等学校物理系课程的一些问题,包括:综合大学和师范大学物理系有些什么课程?这些课程是怎样安排的?进度如何?主要采用那些参考书?等等。为了解答这些问题,帮助读者进修,本刊征得高等教育部综合大学司和教育部高等师范教育司的同意,特将"综合大学物理专业教学计划(四年制)"和"高等师范院校物理系科教学计划的简单介绍"发表在下面,并同时发表陈家昕同志写的"我对综合大学物理专业四年制教学计划的认识"和各至同志写的"对中等学校物理教师自修物理的一点意见"两文供大家参考。     

Traveling wave tube measurements for low-frequency properties of underwater acoustic materials

A traveling wave tube measurement technique for measuring acoustic properties of underwater acoustic materials was developed.Water temperature and pressure environments of the ocean can be simulated in a water-filled tube,and the acoustic parameters of samples of underwater acoustic materials are measured in the range of low-frequency.A tested sample is located at central position of the tube.A pair of projectors is separately located at both ends of the tube.Using an active anechoic technique,the sound wave transmitting the tested sample is hardly reflected by the surface of secondary transducer.So the traveling sound field is built up in the tube.By separately calculating the transfer functions of every pair of double hydrophones in the sound fields from the both sides of the sample,its reflection coefficients and transmission coefficients are obtained.In the measurement system,the inside diameter of the tube isΦ208 mm,the working frequency range is from 100 to 4000 Hz,the maximum pressure is 5 MPa.The reflection coefficients and transmission coefficients of a water layer and a stainless steel layer samples are measured actually and calculated theoretically.The results show that the measured values are in good agreement with the values calculated,and the measurement uncertainty is not greater than 1.5 dB.     

Theoretical analysis of the ship noise demodulation spectrum harmonic clan feature

The structure law of the ship noise demodulation spectrum harmonic clan feature and corresponding applications to the recognition problem are studied by theoretical derivation and sample analysis.In order to recognize the propeller blade-number,the ship propeller cavitation noise model is established on the basis of five hypotheses.Further,the mathematical expressions of the structure law are deduced by the model.And the class space of the propeller blade-number is analysed mathematically.The results can be applied to target recognition as expert knowledge.Finally,the demodulation spectrum harmonic clans of experiment samples are obtained by using the wavelet packet.The structure law is validated by the statistic analysis of experiment samples.It is shown that the statistical average results of experiment samples are consistent very well with the theory structure law,and 78.6% of the samples basically accord with the theory structure law.     

A passive synthetic aperture phase correction algorithm for the asymmetric twin-line array sonar

A passive synthetic aperture based on phase correction algorithm for solving the port-starboard discrimination problem in the non-aligned towed twin-line array sonar,is de- scribed.This method creates a virtual array through applying the estimated phase correction into one array of twin-line arrays.Because the synthetic virtual array is aligned with the other array in twin-line arrays,the right port-starboard discriminated results can be obtained by array processing based on the new synthetic twin-line array.The effect of proposed method has been shown by simulated and sea-trials results in towed twin-line array sonar.With low extra computational loads,the proposed method is easy to apply to the practice.