Showing papers by "University of Science and Technology of China published in 1983"

Anomalous Melting Properties of Some Classical Monolayer Systems

Abstract: The responses to shear stress of monomolecular films of fatty alcohols, ${\mathrm{C}}_{n}{\mathrm{H}}_{2n+1}\mathrm{OH}$, spread on water have been studied for $n=20, 21, \mathrm{and} 22$. A compression-induced melting transition has been observed for the first time.

Centro‐symmetric technique for measuring shear modulus, viscosity, and surface tension of spread monolayers

Abstract: We have constructed an apparatus which enables one to measure, simultaneously, the shear modulus, the viscosity, and the surface pressure of a monomolecular film on water under a hydrostatic compression. It is particularly suitable for measurements of the static shear modulus of insoluble monolayers. A capillary wave generator/detector system was also incorporated to determine the surface pressure. The trough is a Teflon cup 12.7 cm (5.4 in.) in inner diameter with sloping interior sides. As the cup is raised, while maintaining the water elevation fixed, the film is uniformly compressed. A rotor suspended at the center from a fine torsion fiber is used to measure the mechanical properties (surface viscosity and/or surface shear modulus). To measure the quasistatic shear properties, the cup is rotated through a small angle and the residual deflection of the rotor determined. Dynamic shear response is probed by studying transient torsional oscillations following a sudden angular displacement of the torsion ...

Non-linear thermal stability of bimetallic shallow shells of revolution

Abstract: In this paper, a theory for non-linear thermal stability of open bimetallic shallow shells of revolution under a uniform temperature field is developed. To apply the theory to the particular case of some elastic elements in precision instruments, this paper discusses two important kinds of shells, the bimetallic shallow spherical shell with a circular hole at the center and the bimetallic truncated shallow conical shell. The more accurate solutions are obtained by the modified iteration method. All results are expressed in curves which may be applied directly to the design of the elastic elements.

A generalisation to several dimensions of the Neuberg-Pedoe inequality, with applications

Abstract: A well-known inequality relating the areas and squares of the sides of two triangles is generalised to higher-dimensional euclidean spaces. Extension of the results to non-euclidean spaces is also considered.

Is the Periodicity in the Distribution of Quasar Redshifts an Evidence of Multiply Connected Universe

Abstract: The periodicity in the distribution of quasar redshifts is interpreted assuming that the cosmological space is a topologically compactified manifold like three-dimensional torus. The present size of such compact space is estimated at the order of 600 Mpc.

The phases of insoluble monolayers: Comparison between the surface pressure‐molecular area (Π‐A) diagram and shear modulus measurements

Abstract: Simultaneous measurements of the surface pressure‐molecular area (Π‐A) diagrams and the shear modulus of a series of long chain aliphatic alcohols C18OH, C20OH, C21OH, and C22OH spread on water indicate that the conventional phase assignments based on the compressibility are not reliable.

Spatial effect in a multiple IR photon decomposition experiment using a Gaussian laser beam.

Abstract: Since the IR multiple-photon decomposition probability of polyatomic molecules is a function of radiative fluence, the measured fraction of the dissociated molecules could be affected by the spatial distribution of radiation. In this paper the influence of the radiative distribution of a Gaussian beam on measured probability is investigated in detail. The main conclusions are that, for two special cases, namely, cylindrical beam and double-cone beam, one will be able to get information of the fluence dependence of real decomposition probability from measured energy dependence of average probability by means of a log–log plot. This article will be helpful for consideration of experimental conditions, summarizing of data, and comparison of the results of different experiments to avoid possible confusion.

Theory of Imperfect Nonconventional Single-Mode Optical Fibers

Abstract: This paper presents a theoretical frame-work for analyzing, in a general way, the imperfect nonconventional optical fibers met with in practice. Spun and twisted fibers with various imperfections are taken as specific examples to illustrate the general theory. Super-local modes of such fibers are found to be quasi-circularly polarized. Some advantageous features of spun fibers are viewed from the standpoint of mode conversion-reconversions. Couplings between the super-local modes caused by various imperfections are much weakened as compared with couplings between the ordinary (or ideal) modes, thus facilitating the statistical calculation of random imperfections in nonconventional fibers of long lengths. On the basis of this statistical study, an attempt is made to deal with quantitatively, perhaps for the first time, the all-important tolerance problem relating to long-length nonconventional fibers.

Geochemical model for the genesis of Gongchangling rich magnetite deposit in China

Abstract: Based upon geological and geochemical data on the genesis of Gongchangling rich magnetite deposit, it is suggested that the deposit is of multi-genesis, and a three-stage geochemical model for the genesis of the deposit is proposed: (1) Sedimentary stage: the deposition of BIF (magnetite-quartzite) was accompanied by high-grade magnetite (hematite)-siderite ores which are intercalated with magnetite-quartzites as lenses or stratoid shoots. (2) Metamorphic stage: in response to metamorphism, siderite, was decomposed into magnetite and graphite with decreasing fO2 and increasingPCO2. In the marginal parts of magnetite-siderite ores or within the thin-layered interbeds where fO2 was high relative toPCO2 were formed graphite-free rich magnetite ores. (3) Hydrothermal stage: as a result of later hydrothermal process diffusive metasomatism between the rich ores and the host rocks and silica leaching took place, thus giving rise to the rich magnetite ore of metasomatic type and altered rocks.

Infrared spectra of a-Si:H, Cl films

Abstract: Films of amorphous silicon (a-Si:H,Cl) containing about 10 atomic % hydrogen and 2–8 at % chlorine have been prepared using the r.f. glow-discharge technique with a mixture of H 2 and SiCl 4 . The infrared spectra showed in addition to the hydrogen induced absorption bands at 2100, 2000, 840, 890 and 860 cm −1 the following new absorption lines: 545 cm −1 due to SiCl stretching, 787 and 737 cm −1 which might be caused by the Si-HCl bending vibrations. The absolute chlorine content was measured using sulphocyanic mercury spectrophotometric and chlorine ion selective electrode methods.

The effects of emission line identification on the redshift distribution of QSO's

Abstract: We use the QSO's in the catalog compiled by Hewitt and Burbidge (1980) as the sample to analyse for the selection effects in the redshift identification. The results show that the redshift distribution caused mainly by the selection effects has almost same global feature as those given by the observations. The analysis leads us to conclude that the observational redshift distribution of QSO's should be heavily affected by these selection effects, and that attention should be paid to them in the investigations of the redshift distribution, the origion of redshift, and the evolutionary properties of QSO's.

Thermodynamics on cavitation

Abstract: Many studies on cavitation phenomena were based on the theory of single bubble motion which was first put forward by Rayleigh in his 1917 article and later developed by Plesset et al.[1]. By this theory, only some effects of forces were taken into consideration from hydrodynamics leaving out any thermodynamical effects such as matter interchange between liquid and gaseous phases. Strictly speaking, the theory may be suitable for discussing expansior or/and contraction motion of a bubble formed in liquid, but this theory does not cope with cavitation behaviors in general. In this paper, the cavitation conditions and similarity problems are discussed with thermodynamic effects taken into consideration in addition to the hydrodynamic ones.

The velocity of the collective motion of sedimentation of sand and clay

Abstract: In this article, we shall discuss the velocity of the collective motion of sedimentation when the concentration of clay particles is very high. We believe that the problem of the so-called velocity of the collective motion of sedimentation is not a real problem of sedimentation in physical nature, but it is a problem of filtration in the porous medium which is composed of colloidal clusters. That is to say, those clusters consist of water and clay particles. It is a problem of the water passing through the porous medium. Based upon this consideration, we put down the mathematical expression of the velocity of the collective motion of sedimentation. In comparing with the theoretical curves with the experimental data of the Institute of Hydraulic Research, of the Yellow River Conservancy Commission, we get congruous results.

Faraday Rotaion in Monomode Fiber with Axially Varying Magnetic Field

Abstract: A simple integral formula is derived for calculating the total Faraday rotation in a monomode optical fiber produced by an axially varying magnetic field. While Faraday rotation in coiled monomode fibers has been studied by the use of Jones calculus, the author has found that Miller’s theory of periodic coupling particularly useful in calculating the Faraday rotation produced in a fiber of the helix form.

Some Recent Developments in Astrophysics

Abstract: Whenever one talks of Astrophysics in meetings, like the present one, primarily devoted to Contemporary Needs, one has to justify the choice of subject. It is generally thought that even if Astrophysics is ‘contemporary’, it is certainly not a ‘need’. After all, it has no obvious applicability to technology (like Solid State Physics or Laser Physics have) or even a hope of supplying us with new energy resources in the near future (like Plasma Physics does). It can be argued that the underdeveloped countries (calling a spade a spade) cannot afford to ‘waste their time’ on star-gazing instead of solving their present problems which must be admitted to be numerous. We contend that the answer given by History to this question is an emphatic “No!” Only the star-gazers have progressed In fact the third world can not afford to neglect star-gazing. It certainly needs to acquire a technology, but it can not do so by trying to buy, or transplant, the highly developed technology of the West. Instead an indigenous technology must be developed which is suitable to the resources and conditions of the region. For this purpose the underdeveloped countries should concentrate on the fundamentals of physics and provide opportunities for its own scientists to work on the development of new technologies. If they merely try to solve their current problems they will be like the primitive man who refused to sit and make a spear because he could not spare the time from hunting. If the underdeveloped countries do not spare the time from hunting for solutions to immediate problems they will condemn themselves to a primitive existance.

Low temperature\(\lg f_{O_2 } - pH\) diagrams of sulfur isotope evolution in an equilibrium hydrothermal system

Abstract: According to Sakai-Ohmoto's theory regarding the evolution of sulfur isotopes in hydrothermal systems, in conjunction of new data on chemical resaction equilibrium constants and equilibrium isotopic fractionation factors as well as on individual ion activity coefficients of aqueous sulfur species, the following lgfo2.-pH diagrams are constructed: a) mole fractions of aqueous sulfur species (Xi), b) stability fields of some minerals in the Fe-S-O system, c) diagram depicting the oxidation-reduction-state ratio for aqueous sulfur species (R′) d) isotopic compositions of sulfur compounds (\(\delta S_1 ^{34} \)).