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Amplitude-difference method in the estimation of ultrasonic attenuation

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Chinese Journal of Acoustics 1990年第3期9卷 256-262页

作者： LIN Chuan, ZHOU Kangyuan, ZHANG Daofa ZHU Shihong(University of Science & Technology of China)LIN Liwu YE Zheng(The Union Hospital of Fujian Medical College)

In this paper a new method of ultrasonic quantitative diagnosis is discribed. This method can elminate the effect of system deviation and lessen the the effect of beam radiation diffraction. In can be spplied together with many kinks of B-scanners. To verify the method, this paper has shown a new method to make a tissue phantom and a special apparatus. The results show that the method is useful in the diagnosis of diffuse liver diseases, tumors and cancers.It is also useful in the appraisal of the health and the stages of fetus.

关键词： deviation attenuation ultrasonic verify appraisal scanner overlap diffuse thick assumed

SEPARATION AND DETERMINATION OF FIFTEEN RARE-EARTH ELEMENTS IN ROCKS

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中国科学B辑(英文版) 1984年第9期27卷 958-969页

作者：伊丽莹王德恭胡仁桥张凤秋 Institute of Geology Academia Sinica Beijing Beijing

This article is engaged in the research of extractive chromatographic method for the sep-aration of 15 rare-earth elements with P507 （iso-oetel iscetyl phosphate） as stationary phase,silanization porous microbeads silica gel as support, and hydrochoric acid-sodium chloride asmobile phase. The sodium chloride in eluant has accelerated the speed of rare-earth separa-tion. The base line separation can be achieved for all the 15 rare-earth elements. The authorshave proposed a simple and rapid method of determination of the 15 microrare-earth ele-ments in rocks using extractive chronmtographic enriched separation and ICP spectrometrydetermination, and accurate results for rare-earth elements have been obtained.

关键词： enriched stationary engaged silica granite basalt quartz porous evenly deviation

DETERMINATION OF GEOSTROPHIC FLOW BY APPLYING THE PRINCIPLE OF MINIMUM ENERGY AND THE INVERSE METHOD

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Chinese Journal of Oceanology and Limnology 1989年第1期7卷 43-58页

作者：邹建生袁业立 Institute of Oceanology Acadenaa Sinica

This article gives a computing method to calculate the geostrophic current. The fact that kinetic energy of geostrophic motion and geostrophic potential energy reach minimum simultaneously, Fomin’s "principle of minimum kinetic energy" is equivalent to the principle of minimum geostrophic potential energy . We concluded that horizontal geostrophic velocities at different depths are along the same direction . Combining our method with C. Wunsch’s inverse method we can obtain the velocity components along and normal to the hydrographic sections . We used and analysed CTD and current meter data of " Experiment No . 3 " exploration, December 1985-January 1986, in the west Pacific Ocean - Philippine area.

关键词： sections concluded salinity Philippine depths north inverse analysed deviation divide

DIRECTIONAL SPECTRUM ANALYSIS OF INTERNAL WAVES IN THE SEA OFF SYDNEY, AUSTRALIA

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Chinese Journal of Oceanology and Limnology 1991年第1期9卷 15-24页

作者：方欣华肖良 Ocean University of Qingdao 266003 South China Sea Institute of Oceanology Academia Sinica Guangzhou 510300

The directional-spectrum model of internal waves in shallow seas given by Xiao and Fang (1991 )was used to analyze the observation data gathered in April, 1981, in the sea off Sydney,Australia.Some reasonable results were obtained. The energy ratio between Wavemodes 1 and 2 was about 2 for most frequencies and was up to 8 at o = 0.23 cph.Wave components with frequencies 0.1-0.8 cph were generated in the deep sea,and propagated onshore,while those with frequencies higher than 0.8 cph were locally generated by the interaction between longshore currents and bottom topography.Several surveys were carried out in the sea off Sydney, Australia (Cresswell, 1974,Cresswell and Boland, 1981 ,and Fang,Boland and Cresswell, 1984). The survey performed in April 1981 by Fang, Boland and Cresswell (1984) was outstandingly successful. To draw some deterministic and stochastic characters of internal waves, Fang, Boland and Cresswell (1984) and Fang (1987) analyzed these data gathered in 1981 and obtained some

关键词： gathered Australia directional deterministic Sydney shallow currents AUSTRALIA stochastic deviation

The Stability of Large-Scale Horizontal Air Motion in the Non-linear Basic Zephyr Flow under the Effect of Rossby Parameter

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Advances in Atmospheric Sciences 1991年第2期8卷 149-164页

作者：杨芳林 Institute of Atmospheric Physics Academia Sinica Beijing 100029 Chinahe stability of large-scale horizontal motion in the atmosphere is discussed in this paper by using qualitative analysis theory of non-linear ordinary differential equations. Both the non-linear distribution of basic Zephyr flow and the variation of geostrophic vorticity along the latitude (f=f0 + βδy ) are all included in this paper's mathematical model so as to analogue the background field of large-scale horizontal air motion more really in the rotating reference frame of the earth. Some significant results are drawn out from this paper and the conclusions of Li(1986)'s and Wan et al.(1990)'s are extended widely.

The stability of large-scale horizontal motion in the atmosphere is discussed in this paper by using qualitative analysis theory of non-linear ordinary differential equations. Both the non-linear distribution of basic Zephyr flow and the variation of geostrophic vorticity along the latitude (f=f0 + βδy ) are all included in this paper's mathematical model so as to analogue the background field of large-scale horizontal air motion more really in the rotating reference frame of the earth. Some significant results are drawn out from this paper and the conclusions of Li(1986)'s and Wan et al.(1990)'s are extended widely.

关键词： ordinary qualitative rotating vorticity latitude analogue bifurcation really deviation equilibria

PREPARATIVE AND STRUCTURAL STUDIES ON THE SUPERCONDUCTING PHASE YBa2Cu3O7-d

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中国科学B辑(英文版) 1988年第5期31卷 3-12页

作者：唐有祺林炳雄张婉静刘振义郑香苗吴念祖邵美成李传义陈凯旋李建中 Institute of Physical Chemistry Peking University Department of Physics Peking University

Reasonably homogeneous samples were obtained by following the formula Y0.334Ba0.666CuO3-y andusing citric acid as a complex-forming agent to improve the dispersion of the metal oxides. We havealso found that the variant condition in preparative procedure leads to variant deviation from tetrago-nality and that more pronounced deviation gives better superconducting properties. The crystal structure determined from X-ray powder diffraction diagrams confirms the stoichiom-etry of the metal ions and gives the positions of the oxygen atoms. The orthorhombic or pseudo-tetragonal unit cell with a=3.893, b= 3.813 and c= 11.687 A contains YBa2Cu3O7. It is composed ofthree perovskite cubes with three copper atoms at their corners, the two barium atoms at the centers ofthe top and bottom cubes, and the yttrium at the center of the unit cell. The oxygen atoms sit on centersof cube edges. The positions （0 0 1/2） are vacant. The vacancies represented by （0（1/2）0） cause the ar-rangement of atoms to lose tetragonal symmetry, and have far-reaching effect for this phase. The yttriumand barium atoms are coordinated in a cuboctahedron respectively with four equatoria oxygen atoms at（0 0 1/2） and two at （0 1/2 0） removed. In the light of bond valence theory we can infer from the in-teratomic distances Y-O, Ba-O and Cu-O that the occupancy of the oxygen atoms at （1/2 0 0） is wellbelow unity while the positions （0 0 1/2） are vacant, the formula of the phase is YBa2Cu3O7-d, thefraction of Cu（Ⅱ） and （Ⅲ） for the set of copper at （0 0 0） is respectively d/0.5 and （1-d/0.5）, and0.2

关键词： tetragonal deviation barium citric valence corners cube yttrium perovskite removed

INFORMATION CONDITIONS FOR A CLASS OF LIMIT THEOREMS FOR THE SEQUENCE OF m-VALUED RANDOM VARIABLES

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Chinese Science Bulletin 1990年第3期35卷 182-186页

作者：刘文 Hebei Institute of Technology Tianjin 300130 PRC

Let {X_n, n≥1} be a sequence of random variables taking values in S={1, 2,…, m} with the joint

关键词： relative entropy density deviation of entropy density limit theorem.

SEA FLUX OF TRACE METALS IN SAANICH INLET

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Chinese Journal of Oceanology and Limnology 1989年第4期7卷 345-354页

作者：詹滨秋 Wong C.S Johnson K.W Institute of Oceanology Academia Sirica Qingdao Insititute of Ocean Sciences Canada

The sea fluxes of trace metals, POC, and settled material were studied in anoxic sea water, Saanich Inlet, B.C., Canada with sediment traps. This paper discusses the change of mass fluxes of sediment, trace metals and POC for various seasons and depths. The annual mean of settled material is 1.56 g.m-2 .a-1, 84.6 mg. m-2. a-1 for POC, 60.0 mg.m-2. a-1 for Cu, 16.5 mg.m-2.a-1 for Pb, 189 mg.m-2. a-1 for Zn, 2.20mg.m-2.a-1 for Cd,699 mg.m-2.a-1 for Fe,38.8 mg.m-2.-1 for Co, and 84.6 mg.m-2.a-1 for Ni.The relations between the average fluxes of trace metals and POC, the fluxes of trace metals and settled matter, and the sea fluxes of trace metals and Fe are in linear progression. The resident times of elements as calculated from sea flux, are 1.1 a. for Cu, 0.014 a. for Pb, 0.50 a. for Zn, 3.8 a. for Cd, 0.16 a. for Fe, 0.39 a. for Co,and 1.14 a. for Ni.The order of resident times is as follows: Pb-Fe-Co-Zn-Cu-Ni-Cd. The metal resident times in Saanich Inlet are shorter than the values estimated for the

关键词： settled anoxic resident dissolved shorter residence depths recycling manganese deviation

THE MECHANISM OF AUTOMATIC CONTROL WITH VARIABLE STRUCTURE-PARAMETERS

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Chinese Science Bulletin 1991年第2期36卷 167-169页

作者：涂承媛 Department of Automatic Control Beijing Polytechnic University Beijing 100022 PRC

The general form of the dynamic response of a controlled process is shown in Fig. 1, where E is the deviation of the controlled variable U from its set-point value U0 （i. e. E= U0-U）. For convenience in discussing, we transform the curve in Fig. 1 into that in Fig. 2 a t-domain curve of |E|. Now, we discuss a certain period of variation of the curve in Fig. 2, e.g. a time interval between to and t4.We partition this period of variation into four subintervals: t0—t1, t1—t2, t2—t3 and t3—t4. It is easily seen that, in the first and the third subintervals, the rate of change

关键词： deviation partition convenience brought unfavorable eliminate fourth weakened tendency hence