Table of Content

31 December 1984, Volume 2 Issue 4

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Articles

MULTIPOLE MECHANICS OF MATERIALS WITH MICROSTRUCTURE

R. K. T. HSIEH

1984, 2(4):  283-293. 

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This expository paper presents some recent results on the mechanical multipole description which consists in approximating the influence of the microstructure of a material as those arising from lictitious body forces and couples of ditferentmultipole orders.

MICROWAVE COMPUTERIZED TOMOGRAPHY

ZHU LONGLONG, GU BENGLI, WEI YU

1984, 2(4):  294-301. 

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In this paper, the theory and practice of transmission microwave OT performed by the authors are stated. How the various factors in microwave OT imaging effect the quality of image is discussed. The tomography scanner apparatus were established and OT-date of simple phantoms were collected. Using the reconstructive program, we nave got the microwave OT images. It is shown that we can get suitable image and resolution for low contrast objects, and valuable information for high contrast objects though the pseudomorph. appears seriously.

OBSERVATIONS OF THE ATOMIC ARRANGEMENT IH CRYSTALS BY MEANS OF HIGH RESOLUTION ELECTRON MICROSCOPY

YE HENGQIANG

1984, 2(4):  302-309. 

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The atomic arrangement in crystals can be seen directly by means of high resolution electron microscopy. An outline of the theoretical analysis for imaging conditions was given. Three kinds of high resolution images were explained with examples:structural image representing the projection of crystal structures and defects; ultra-high resolution images showing structural details beyond the point-to-point resolution under special conditions; "superstructure" image exhibiting the ordered atom columns in binary alloys.

RESEARCH AND DEVELOPMENT OF A TRANSMISSION SCANNING ACOUSTIC MICROSCOPE OPERATING AT 300~700 MHz

CHEN GELIN, LI DEJIE, ZHANG FENGXI, LUO SHUYUN, YING JIANING, ZHOU HONGPU, HU SIZHENG, JIN FENNIAN, ZHOU QIBO, WANG HUAJIAN, ZHANG KEQIAN

1984, 2(4):  310-321. 

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The research and development of a transmission scanning acoustic microscope operating at 300-700MHz is described. The design and construction of the microscope, the acoustic transducer-focusing system, the mechanical microwave and electronic systems are presented. Theoretical analysis and experimental results show that the resolution of the microscope is not worse than 2μm, i. e. the resolution reaches the refraction limitation. Finally, images of some specimens obtained by using the acoustic microscope are given.

A NEW TRANSDUCER-FOCUSING SYSTEM FOR ACOUSTIC MICROSCOPE-GLASS-METAL BASED CONCAVE SPHERICAL TRANSDUCER

LI DEJIE, CHEX GELIN, ZHANG KEQIAN

1984, 2(4):  322-330. 

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The transducer-focusing system is the most important part in a scanning acoustic microscope. We proposed and developed a new type of such system-glass-motal based concave spherical transducer. Compared with Quate's plain transducer-simple lens system and Chubachi's gold cup based concave transducer, there are some unique advantages in our new system. The scattered acoustic field outside the lens is avoided, higher resolution is obtained more easily, and the structure and technology of our new system are appropriate for frequencies up to GHz range. The structupe, material and technology of the metal-glass based concave transducer are described, and the theoretical analysis as well as the experimental results are presented.

THE ANALYSIS OF IMAGE DEFORMATION IN HOLOGRAPHIC LENS TYPE OF INTERFEROMETER AND THE DESIGN OF COAXIAL HOLOGRAPHIC LENS TYPE OF INTERFEROMETER

HE ANZHI

1984, 2(4):  331-337. 

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This paper analyses the deformation of the reconstructed image of holocrram and its interferogram in holographic lens type interferometer and shows the way of decreasing deformation. A new optical system of holographic lens type of interferometer-is designed which needs no strict vibration isolating in static holography and in dynamic holograohy the good dynamic hologram can be obtained without the strictly mode-selecting laser source.

NUMERICAL MULTIFREQUENCY ULTRASONIC HOLOGRAPHY

OUYANG XITONG, ZHOU ZIWEN

1984, 2(4):  338-344. 

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This paper discusses the fundamental relation for reconstructing a multifrequency hologram with computer. For acquiring better images, we study the dependences of the frequency bandwidths, the aperture and frequency discrepancies on the point expansive function of the single object point.
It is useful for decreasing ambiguity of the image to increase frequency bandwidths and aperture size.
The amplitude and the phase of ultrasonic waves scattered by two thin metal wires in the water tank are measured. The image of the two thin metal wires is given by computer.

BIREFRINGENCE IN CURVED SINGLE-MODE OPTICAL FIBERS DUE TO WAVEGUIDE GEOMETRY EFFECT PERTURBATION ANALYSIS

FANG XISHENG, LIK ZHONGQI

1984, 2(4):  345-353. 

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The field deformation in curved step-index single-mode circular optical fibers and the birefringence induced by waveguide geometry effect are analyzed by perturbation method and the analytic result is given. The values of the birefringence are proportional to a²/R₀² and are much loss than that induced by stress.

ANALYSIS OF THE OPTICAL GUIDED-WAVE FIELDS BY THE RETARDED-POTENTIAL METHOD

LAI ZUYOU, FAXG JUXXIN

1984, 2(4):  354-360. 

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In this report,, it is shown that by applying Ewald-Oseen'g extinction theorem to a slab optical waveguide, the distribution of the guided-wave fields and the mode condition can be systematically obtained. Besides, it can be seen that the guided-waves are essentially eigen-states of the dipolar field of the waveguide. The characteristic properties of the optical guided-waves can be interpreted in terms of our elementary-excitation hybridization scheme.

EXTENDING THE SPECTRAL RESPONSE OF DOPED POLYCRYSTALLINE n-TiO₂ PHOTOANODES

SHI YUANXIAXG, DAI XIAOROXG, GAO QINHUA, SUN BIROU

1984, 2(4):  361-367. 

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A doped thin film polycrystalline n-TiO₂. rutile photoanode is obtained by thermal oxidation of Ti sheet in air at 650-700℃ for 3 hrs. The Ti shoot is previously coated with butanol solution of nitrates of corresponding doping elements. The photoanode is then activated in a stream of hydrogen gas. Elements such as Al, Y, Cr, Fe, Zn, Cd, La, Nd, Ce, La-Cr and Y-Cr are doped respectively. Doping with Y-Cr or La-Cr simultaneously makes the possibility of not only enhancing the quantum efficiency of the photoanode, but also extending its spectral response to visible light, in which TiO₂/Y-Cr(4:1)is the best. An explanation of extending its spectral response is suggested which attributes to the formation of d band.

A METHOD OF FAST MODELING

WANG ZHIZHONG, ZHANG ZHONGJUN

1984, 2(4):  368-372. 

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This paper proposes a new method of fast modeling for computing the residual sum of squares, determinating the model order and estimating the parameters by traditional least squares.
The residual sum of squares can bo easily computed before parameter estimation. Thus, the computing work for establishing a model with unknown order by this method is nearly equal to that with known order. Alsc this method requires lass storage capacity., so that the modeling work can be performed even with a pocket microcomputer(e. g. FX-702P).

APPLICATION OF THE MAXIMUM (OR MINIMUM) THEOREM OF TOPOLOGICAL SPACE TO BIOLOGY

LU SHOUKUN

1984, 2(4):  373-376. 

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This paper deals mainly with the application of the theorem:"The continuous function on compact topological space X can attain maximum or minimum at a point somewhere in X" to genetics theory, livestock, aquatic breeding and time-biology.