Table of Content

20 September 1997, Volume 33 Issue 5

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Abstraction of Programming Languages and a Model of Language Family

ZHANG Naixiao,ZHENG Hongjun

1997, 33(5):  650-657. 

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Models for programming languages play an important role for studying properties of programming languages. Based on the concept of language abstraction and under an algebraic model for programming languages we build, this paper presents the semantics of three kinds of relation between languages, i.e. inheritance, extension and shielding. Then the paper proposes a model of language family which is constructed under the three kinds of relation. This model can be a theoretical basis for researching relations between languages and model oriented transformational software development methodology.

Convergence of Pressure for Viscosity Splitting Schemes

YING Lungan

1997, 33(5):  545-553. 

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Three dimensional initial boundary value problem of the Navier-Stokes equation is considered. The equation is split into an Euler equationand a non-stationary Stokes equation within each time step. Under the hypothesis that the original problem possesses a smooth solution, the L² norm of the errors of the pressure is obtained.

A Remark on the Nonlinear Stability of Discrete Shocks for Single Hyperbolic Conservation Laws

ZHOU Tie

1997, 33(5):  554-560. 

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For the strictly monotonic schemes approximating single hyperbolic conservation laws, the asymptotic stability of the discrete shocks is widely believed to have been worked out. But in fact, in all of the former works, both in results and in proofs, some mistakes occurred. In the present paper, we expose the correct result and give a rigorous proof.

On the Limit Distribution of n-year Term Life Insurance

YANG Jingping,WU Lan

1997, 33(5):  561-566. 

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Limit distribution of a homogeneous portfolio of n-year term life insurance is discussed. Under the force of interest modeled with white noise process, recursive formula for the density of the limit distribution is got.

The Series Method for Any Sector

YAN Xianggan,WU Jike

1997, 33(5):  567-573. 

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A practicable analytic solution is obtained for any sector by means of Fourier series with singular items. It is proved that the method is equal to Williams' method of separation of variables. The non-linear characteristic equation is transformed into the polynomial equation.

Non-isothermal Long Pipelines Leak Detection and Location

TANG Xiujia

1997, 33(5):  574-580. 

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In this paper the heat exchange between the pipelines carrying higher temperature fluid and ambient environment is analyzed. We have proposed a new complex thermal and hydraulic models, in which the flow regime, viscosity-temperature characteristics, density-temperature characteristics and specific heat-temperature characteristics, etc., of the running fluid in the pipelines are considered. The work-heat exchange of the frictional force is taken into account as well. For early detection and accurate location of leaks on the non-isothermal pipelines in accordance to pressure, flow rate and temperature, etc., SCADA(Supervisory Control and Data Acquisition) measurements, at both inlet and outlet, the hydraulic and thermal differential equation system are driven, and the quick algorithms for solving them are also discussed. Because almost all the crude oil produced in China are highly waxy, highly viscous and with a high solidifying point, a series of experiments for leak and rupture detection are carried out on the long heating crude oil transport pipelines, verifying that the suggested method is both accurate and efficient.

Robust Oscillation Analysis for a Family of Polynomials

YU Wensheng,HUANG Lin

1997, 33(5):  581-586. 

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The robust oscillation for some polynomials' families is discussed. A vertex verification result for the robust oscillation of polytopic polynomial family, under some conditions, is obtained. Moreover, the number of vertex polynomial to be checked can be reduced for interval polynomial family and diamond polynomial family. A counter-example is given to show that these vertex verification results can't be directly generalized for root distribution invariance of polynomial families.

Generalization of Hellmann-Feynman Formula

ZHU Wusheng,ZHAO Xinsheng

1997, 33(5):  587-591. 

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The time-independent Hellmann-Feynman formula was generalized into a time-dependent Hamiltonian system. A relation between the generalized Hellmann-Feynman formula and the Berry phase was found. A possible application of the generalized Hellmann-Feynman formula in the inverse quantum scattering problems is speculated.

Determination of Band-gap in SnO₂ Nanoclusters at Room Temperature

WANG Dehuang,CHENG Humin,LIANG Ruisheng,TANG Zhelie

1997, 33(5):  592-594. 

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At room temperature band-gap in SnO₂ Nanoclusters for an average diameter 6 and 10nm are determined. The values of band-gap are 3.543 and 3.351eV, respectively. The results are compared with the calculated values from the effective-mass approximation model.

Experimental Test of the Isotropy of Two-way Speed of Light

CHEN Shaoguang,LIU Baocheng,YI Heling,CHEN Fu,HU Kexin,LU Qihu,YI Sunsheng,PENG Wenhao,ZOU Wendong,ZHU Yubin

1997, 33(5):  595-599. 

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By means of the common mode restraint technique the error caused by the frequency instability of laser has been decreased to the level of 2×10^-20 in Δv/v. By means of the heterodyne frequency shift technique and the computer storage technique the sensitivity of beat frequency achieved 1×10^-4Hz. In our experiment the isotropy of two-way speed of light has been proved at the level of 1×10^-18 in Δc/c, which represents a 2500-fold improvement on the previous best measurement given by Brillet and Hall.

Preliminary Study on Impact of the Climate Forcing on the Hierarchical Structure of Hemisphere Surface Temperature

XIN Guojun

1997, 33(5):  600-605. 

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The atmosphere CO₂ gas, solar activity and volcanic eruptions are three major climate forcing. By comparing the climate forcing with the hierarchical structure of hemisphere surface temperature variations during last a hundred years, the possible external cause of the hemisphere surface temperature jump change has been investigated. For abrupt change of long-term climate in the northern hemisphere in 1924 (its timescale is about 77 years) and southern hemisphere in 1939 (its timescale is about 90 years), the greenhouse effect of atmosphere CO₂ gas is unimportant forcing. It is not very possibly caused by the obvious change in astronomical solar constant. For abrupt change of short-term climate in the northern hemisphere before 1924, there is evident corresponding of middle cool/warm period (its timescale is about 14 years) to frequently large volcanic eruptions on the low and middle/the middle and high latitude. The jump changes appeared in the southern hemisphere short-term climate (its timescale is about 5.6 years) is strongly influenced by the solar activity.

Formation of Global Chaos and Halo in High Current Ion Linacs

LIU Pukun,FANG Jiaxun,CHEN Chiaerh

1997, 33(5):  606-612. 

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In recent years, high current ion linacs have become increasingly attractive for applications such as heavy ion fusion and nuclear waste treatment, and these applications have raised strict requirements of low beam losses. During the transport of high current beam in low energy section of linac, a halo surrounding the dense core is one of the main sources of beam losses. In this paper, the test-particle core-interaction model is used to study the beam transport problem of a space-charge-dominated beam in a one-way self-consistency by solving simultaneously the KV envelope and Hill's equations in Hamilton dynamics. The motion of beam particles in phase-space is numerically analyzed by using Poincare mapping technique and Lyapunov exponents. The results show that the envelope oscillations of a mismatched beam can generate parameter resonance of the particle Hamiltonian, and the resonance condition depends only on the effective space charge parameter. The motion of particles near the core can become chaotic with development of the parameter resonance, and the evolution of global chaos will lead more particles near the KV envelope to become halo particles. The results also indicate that the halo can be regenerated, and have a boundary in two dimensional regime.

Atomic Correlations in Solids and Bragg Diffraction

WANG Dehe

1997, 33(5):  613-620. 

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A new method--atomic correlation method for describing structures of solids is presented. We begin with the definitions of atomic correlations, basis vectors of correlations, correlation lattice and reciprocal correlation lattice. We then analyse the different manifestation of atomic correlations in crystals, quasicrystals and amorphous solids. Finally, we discuss diffractions in solids and derive the general form of Laue equation, demonstrating that quasicrystals can also form sharp diffraction patterns.

Blocking Performance in Wavelength-routed Optical Ring Networks

ZHANG Kan,XU Anshi,WU Deming,XIE Linzhen

1997, 33(5):  621-626. 

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Blocking characteristics of wavelength-routed optical ring networks (WRORNs) are evaluated in this paper. It shows that WRORNs can operate quite well with limited resources under light traffic conditions.

A New Measure for Objective Speech Quality Evaluation

WU Shuzhen,POLS L C W

1997, 33(5):  627-632. 

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This paper studies briefly a distance measure for objective quality evaluation of speech communication channels using instantaneous and dynamic spectral features. It is based on studies for subjective and objective quality evaluation and LPC cepstral distance measure. The dynamic spectral feature is expressed by the cepstral regression coefficients. We used the three parameters: cepstral coefficients, cepstral regression coefficients and energy regression cofficients to measure objective speech quality. The experimental results show that the correlation coefficient between this objective measure and the subjective quality evaluation (MOS) is 0.953, it is much better than LPC cepstral distance measure. and other 2 measures.

State-to-state Dielectronic Recombination for Highly Charged Li-Like Ions (Z=72～76)

YE Anpei,MA Meizhong

1997, 33(5):  633-640. 

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The state-to-state dielectronic recombination (DR) rate coefficients of Lithium-like Hf, Ta, W and Re via Δn=0 and 1 resonances have been calculated at the energy range of 0.1～9.0 keV. The calculation based on relativistic multi-configuration Hartree-Fock (HFR) code which includes mass-velocity correction, spin-orbit coupling, Darwin term, and roughly Breit and retardation energies. The variation of state-to-state DR rate coefficients with the electronic temperature, DR type, and the principal quantum number of intermediate resonance states is discussed. The results show that some state-to-state DR rate coefficients are very small, therefore the total DR rate coefficients for some states, such as W⁷¹⁺(1s²2s3d)₀ and (1s²2s3p)₀ are several orders smaller than others, so it would be possible that the particle population of highly charged ions is reversed between some states by DR mechanism.

A PC-Based Platform for VR Development--PCVRS

WANG Hongwu,JIANG Yuquan,DONG Shihai

1997, 33(5):  641-649. 

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This paper discusses a PC-based platform for Virtual Reality (VR) system development--PCVRS. Comparing with the same kind of systems abroad, this paper analyses in detail the features of PCVRS on interactive functions and opening capabilities. As for interactive functions, PCVRS added the Pick & Play interaction, supplied voice as an additional interacting modal and implemented multimodal interaction. The opening capabilities of the system are mainly shown by its support for VRML which is widely used as virtual reality modeling language on Internet. The system even supplies abstract modeling data structure as a uniform interface for various kinds of 3D scene data. By introducing one of the applications developed on this platform , we also tested the performance of this system. The test result shows that for those applications where scenes are not very complicated and the output requirements are not very high, PCVRS has a good interactive performance.

Calculus of Constructions and Its Axiomatization in FBO

SUN Yong

1997, 33(5):  658-668. 

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This paper briefly introduces Coquand and Huet's Calculus of Constructions (CC) and a Framework for Binding Operators (FBO). It then shows CC's axiomatization in FBO. This axiomatization is without an infinite type hierarchy. Specifically, we introduce an extra universe kind above the original universe type in CC. But we allow neither quantification over kind nor introduction of y: kind. Another operator=> is added for typing II types in FBO, since we are only considering a single-sorted FBO. Technically speaking, we translate CC into FBO; i.e. every CC term is typed in FBO. For example, II,i>x:M.N in CC is translated as IIy.u:t=>v in FBO, where x, M and N correspond to y, t and u respectively under the translation. As a result, we demonstrate that FBO is powerful enough to provide an equational platform for CC.

Scaling Symmetry

LIU Shida,LIU Shikuo

1997, 33(5):  669-680. 

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The scaling symmetry is elementary characteristic of characterless scale phenomena such as length of the coast, tubulence, critical phase transitions. The scaling Symmetry is to seek after invariance under scale transformation for dynamical system. The Fiegenbaum constant is a famous invariance via period doubling scaling transformation for chaotic system. The climatic colding and warming change with time scale, but there is also invariance. In mathematically the scaling symmetry may be considered as a interated map, in biologically as a self-reproduction. The self-simitarity of scale transformation is related to spiral structure in nature.

Scaling Symmetry

LIU Shida,LIU Shikuo

1997, 33(5):  669-680. 

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The scaling symmetry is elementary characteristic of characterless scale phenomena such as length of the coast, tubulence, critical phase transitions. The scaling Symmetry is to seek after invariance under scale transformation for dynamical system. The Fiegenbaum constant is a famous invariance via period doubling scaling transformation for chaotic system. The climatic colding and warming change with time scale, but there is also invariance. In mathematically the scaling symmetry may be considered as a interated map, in biologically as a self-reproduction. The self-simitarity of scale transformation is related to spiral structure in nature.