Vol. 48, No. 12 (1999)
1999-06-20
GENERAL
1999, 48 (12): 2149-2153.
doi: 10.7498/aps.48.2149
Abstract +
The usual formally variable separation approach is valid only for completely integrable models. In this paper, we extend the method to a nonintegrable generalized Hirota-Satsuma equations. Some new exact solitary wave solutions and periodic wave solutions of the equations are also obtained.
1999, 48 (12): 2154-2157.
doi: 10.7498/aps.48.2154
Abstract +
A scheme is presented for the teleportion of a Fock superposition state via a degenerate V-type three-level atom and two cavity fields Raman interaction.
1999, 48 (12): 2158-2161.
doi: 10.7498/aps.48.2158
Abstract +
A method of obtaining electromagnetic field tensor for the source of the field possessing both electric and magnetic charges is given. As an example, in Kerr-Newman space-time with a large number of magnetic charges the method is used, and the results are the same as those obtained by making electric charge a complex extension directly to e+iq.
1999, 48 (12): 2162-2168.
doi: 10.7498/aps.48.2162
Abstract +
In this paper we present the analytic expressions of partition lines in the parametric space of a piece-wise smooth mapping describing an electronic relaxation oscillator. The supercritical regions with permission of period-doubling bifurcation, prohibition of period-doubling bifurcation, and complete phase-locking are discussed. Among them the region, where period-doubling bifurcation is prohibited but chaos is permitted is reported for the first time to our knowledge. These kinds of phenomena and regions can be observed in a lot of similar systems.
1999, 48 (12): 2169-2179.
doi: 10.7498/aps.48.2169
Abstract +
In the semi-classical limit, the non-ergodicity of the eigenstates, θk(j), of circular unitary ensemble (CUE) are investigated. To study statistically the non-ergodicity of the eigenstates ofaquantumsystem, a pair of statistical functions,ΦN(j)=∑N-1k=0|θk(j)|4 and ΨN(j)=∑N-1k=0|θk(j)|2, are defined to show the scars and anti-scars respectively. In the frame of Random Matrix Theory,ΦN(j)s and ΨN(j)s for random orthohormal unit vectors are calculated. It is shown that their averages and fluctuations will tend to zero with the increase of N,while they follow the scaling laws. Compared with ΦN(j)s and ΨN(j)s obtained from the eigenstates of the quantum baker's transformation, it is found that, with the presence of scars (or antiscars), the fluctuations of the statistical functions of the eigenstates of the quantum baker's transformation will be greater than those of the random matrices, and tend to zero much slower in the semi-classical limit of N→∞.
1999, 48 (12): 2180-2185.
doi: 10.7498/aps.48.2180
Abstract +
Two kinds of crises with speciality properties in piece-wise-smooth systems are reported. The crises are induced by the discontinuity of the systems. The mechanism of the first kind of crisis is a collision between a forbiden region and an unstable orbit located in the region of chaotic attractor. On the contrary, the second one is produced by the collision between a chaotic attractor and a hole induced by the discontinuous regions of the system. For the first one, the scaling laws of the average laminar lenths and its distribution are 〈τ〉∝-1.8 and P(τ)=1〈τ〉exp-τ/〈τ〉, respectively. Meanwhile, for the second one, the scaling laws are 〈τ〉∝exp(k-1/2) and P(τ)=1〈τ〉·exp-τ/〈τ〉).
1999, 48 (12): 2186-2190.
doi: 10.7498/aps.48.2186
Abstract +
This paper presents a method that restrains a systematical behavior by a synchronistical measure and forces it to repeat a section of chaotic trajectory periodically, so that the high periodic chaotic signal can be obtained. The obtained signal not only keeps the typical features of the chaotic signal but also has the advantages of a periodic signal. The results of the simulation calculation, the experimental circuit and the experimental results about realizing the method on the basis of. Lorenz mode are given. The advantages of this method for applications in secret communication or covering information are discussed.
1999, 48 (12): 2191-2195.
doi: 10.7498/aps.48.2191
Abstract +
This paper presents a linear output feedback synchronization approach for a chaotic Arneodo system. Based on the linear stability theorem, a sufficient condition of asymptotic synchronization is given, and the boundary of the range of the output feedback parameter is given also. Finally, a computer simulation is given to demonstrate the effectiveness of the method.
1999, 48 (12): 2196-2201.
doi: 10.7498/aps.48.2196
Abstract +
A method of controlling chaos based on intermitant proportional pulse perturbation to the system parameters is proposed. The unidimensional and two-dimensional discrete chaotic systems are studied respectively with the method proposed, and a series of stable 2nP and 2n*3mP as well as 128P,192P high periodic orbits are obtained. The analysis shows that the method of intermitant proportional pulse to the system parameters is equivalent to the method of intermitant proportional feedback to system variables for controlling chaos in unidimensional logistic map.
1999, 48 (12): 2202-2207.
doi: 10.7498/aps.48.2202
Abstract +
Artificial object detection and segmentation in natural background are key points of pattern recognition and computer vision.The effect of complex texture of natural background and other factors,make it difficult to segment artificial object from natural background.In this paper,an algorithm based on watershed transform and regional fractal texture analysis is proposed to detect and segment artificial object from natural background.
NUCLEAR PHYSICS
1999, 48 (12): 2208-2214.
doi: 10.7498/aps.48.2208
Abstract +
It has been shown that the Young-Laplace equation based on the balance of the gravitational force and interfacial tension alone cannot produce a valid solution for the profile of a continuous liquid hydrogen layer inside an inertia confinement fusion capsule shell. In the calculated results, the London-van der Waals forces between the liquid and solid (shell) molecules must be included in the equation. The retardation effect of the London-van der Waals forces needs to be taken into account for thick liquid hydrogen isotopes layers. It has been also shown that, in an isothermal environment, a continuous liquid hydrogen isotopes layer with a uniform thickness can only be achieved inside the capsule shell, such as the spherical glass when the gravity is zero or the London constant between the solid and liquid molecules is infinity.
ATOMIC AND MOLECULAR PHYSICS
1999, 48 (12): 2215-2221.
doi: 10.7498/aps.48.2215
Abstract +
An analytical potential energy function for the ground state 3Σ+u of UO2 has been derived using many-body expansion method. The present paper correctly determines the dissociation limits, based on group theory and atomic and molecular reactive statics (AMRS). Using the MP2 (The HF calculation followed by a second-order Moller-Plesset correlation) of Gaussian94W and the RECP (the relativistic effective core potential) for U and basis 6-311G* for O,the present work has optimized the equilibrium geometry for the ground state 3Σ+u of UO2, which is linear O—U—O,whose equilibrium nuclear distance and dissociation energy are 0.17789nm and 14.1036eV.And the metastable structure U—O—O is discovered for the first time,to our knowledge,which is 5.7731eV higher than the stable structure.Then,the potential energy function is successfully used for describing the equilibrium geometry of UO2 and UOO,which is accurate enough in the whole region for dynamical research.
1999, 48 (12): 2222-2227.
doi: 10.7498/aps.48.2222
Abstract +
The potential energy function for ground state X5Σ- of the PuO molecule was worked out by the quadratic configuration interaction of single and double substitution method, based on the approximation of relativistic effective core potential for Pu atom and all-electron 6-311G* basis set for O atom. The calculated results for Re,De,Be,αe,ωe and ωeχe are 0.183nm,7.3909eV,0.3365,0.001642,781.15,and 2.77cm-1,respectively.In addition,the thermodynamic functions ΔH0,ΔS0，ΔG0 and Cp of the PuO(g) in standard state are also calculated,which are -118.88kJ/mol，96.16J/mol·K，-147.55kJ/mol,and 31.5656J/mol·K,respectively. All these results are in good agreement with the experimental data.
1999, 48 (12): 2228-2240.
doi: 10.7498/aps.48.2228
Abstract +
A modified Tersoff potential developed by extending atomic interaction distancehas been applied to simulating the properties of liquid silicon with molecular dynamics. The radical distribution functions with coordination number 6.9 and bond length 0.254nm from the simulation are in good agreement with the experimental results from X-ray diffraction and neutron scattering. The configurations simulated indicate that a chain-network structure is formed among silicon atoms in liquid silicon,and a majority of atoms remain tetrahedral local structure with near-neighbour atoms. The presence of two peaks,~57° and ~102°,in bond angle probability distribution indicates a very complicated structure in liquid silicon. Based on the instantaneous configurations given by the simulation,the local structures in liquid states have been studied with bond-order parameter method. The results show there are ~82% tetrahedron structures in the near-neighbour structures in liquid state and the square deviation of bond-orientational luctuation is about 5.2°. The results also show that except thericosahedron structure,the non-tetrahedral structures may include some other near-neighbour structures.
CLASSICAL AREA OF PHENOMENOLOGY
1999, 48 (12): 2241-2245.
doi: 10.7498/aps.48.2241
Abstract +
Atomic coherence in a Λ system may be created by spontaneous emission.In this paper it is shown that the coherence may lead to lasing without inversion and the features of the effect of the coherence on the laser gain is analyzed.
1999, 48 (12): 2246-2251.
doi: 10.7498/aps.48.2246
Abstract +
The temperature fluctuation of the stainless steel irradiated by a CW CO2 laser is studied. In the experiment, the temperature fluctuation and the temperature rise is measured by the infrared thermal imagers. It is found that the maximum amplitude of the temperature fluctuation is kept constant with the increase of the laser heating time; this is different from aluminum, low carbon steel, epoxylite and polymethylmethacrylate. This characteristic of the stainless steel is determined by the variance of thermal conductivity and thermal diffusivity with the increase of temperature. A thorough study of the effects of the material thermal properties on the temperature fluctuation is needed.
1999, 48 (12): 2252-2258.
doi: 10.7498/aps.48.2252
Abstract +
Optical bistabilities (multistabilities),which are due to the carrier-dependent refractive index of laser diodes (LD),observable on the output curves of tunable external cavity (EC) semiconductor lasers have been studied.As a result,various hysteresis loops with different shapes appearing on curves of N-ν (carrier density-oscillation frequency of external cavity semiconductor lasers) have been analyzed,and corresponding hysteresis loops on (power-frequency) curves have been also calculated.The expression relating reflectivities and spectral broadening factor,for observing the multistability on the N-ν(or P-ν) curves of ECLDs,has been established.
1999, 48 (12): 2259-2265.
doi: 10.7498/aps.48.2259
Abstract +
The dynamical behaviors of onset patterns on the surface of viscous liquid in the large-aspect-ratio container under double-frequency parametric excitation have been investigated theoretically.The calculation shows the lower margin curves of exciting acceleration for pattern formation,the response modes and the frequency spectra of the pattern as well.Furthermore,the bicritical phenomenon found in the double-frequency Faraday experiments is also studied.All of the results from the theoretical calculation are in excellent agreement with those measured by Edwards et al. without any adjustable parameter.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
1999, 48 (12): 2266-2274.
doi: 10.7498/aps.48.2266
Abstract +
By adopting the Bohm type thermal diffusivity coefficient which is applicable to JET,considering the effect of the α particle anomalous diffusion and the dynamic feedback heating,and using the energy transport equations of electron and ion,the plasma temperature profiles of deuterium-tritium (D-T) burning are studied under a given plasma density profile.Some results are obtained:the Bohm type thermal conductivity increases from the center of plasma to the boundary;in order to sustain D-T burning,the dynamic feedback heating power must be present,otherwise,the burning would be extinguished;the power coupling coefficient of α particle with the bulk plasma is less than one in the central part of the plasma,and much larger than one in the outer part;the stronger the α particle anomalous duffusion,the higher the central ion temperature.This is due to the smaller thermal diffusivity coefficient in the central part and the dynamic heating power to increase because of the lower central electron temperature;the energy amplifier factor Q under the Bohm type is smaller than under other types,therefore,the prospect of the Tokamak reactor operation model based on Bohm type is pessimistic.
1999, 48 (12): 2275-2282.
doi: 10.7498/aps.48.2275
Abstract +
A new idea of using two electron beams to widen the bandwidth of a Gyro-TWA is put forward.Theoretical and numerical investigations show that:the new model can produce wideband and high-power output,and its gain is much higher compared with the existing wideband model.When the current of the two beams is 10A,their voltage are,respectively,90 and 153kV,the velocity ratio are 1.0 and 0.62,and their axial momentum spreads are 5.5% and 1.2%,the output saturated bandwidth can reach at least 22%,the peak power,efficiency and gain are 395kW,16% and 62dB,respectively.If we taper the axial guiding magnetic field at the end of the interaction region,a constant bandwidth of 23% can be achieved with the peak output power 280kW.
CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
1999, 48 (12): 2283-2288.
doi: 10.7498/aps.48.2283
Abstract +
A method of generating optical phase conjugation by degenerate four-wave mixing in azo-doped nematic liquid crystal is proposed.The mechanism of liquid-crystal reorientation is analyzed.A simple physics picture is given,the theory is consistent with experiment results.The experiment results will have potential applications in nonlinear optics and other fields.
1999, 48 (12): 2289-2298.
doi: 10.7498/aps.48.2289
Abstract +
Bis (trimethylsiloxy) silicon naphthalocyanine (SiNc) LB films were fabricated to align nematic liquid crystals. Films obtained under different surface pressures exhibit different alignment effects. Films obtained under surface pressure of 15mN/m will induce a planar alignment, while those obtained under 30mN/m will induce a homeotropic alignment. Atomic force microscopy reveals that on films prepared under high surface pressure the SiNc molecules stack into separate monomers or aggregates to form lines of nanometer size with molecular macrocycles perpendicular to the surface of the film and the dipping direction of its formation. In addition, there are grooves of molecular size between the stacked SiNc molecular lines. Similar formation occurs in films prepared under low surface pressures, only instead of molecules all lying perpendicular to the surface, many SiNc molecules are lying obliquely to the film surface or even lying on the surface. The mechanism of the liquid crystal alignment is also discussed.
1999, 48 (12): 2299-2303.
doi: 10.7498/aps.48.2299
Abstract +
The relation between the threshold voltage shift of BF+2 implanted Si-gate PMOSFET and the total γ-irradiation dose has been systematically studied,and the mechanism of γ-irradiation hardening for BF+2 implantation has also been analyzed in detail.The studies show that BF+2 implantation has a strong suppression for the threshold voltage shift of BF+2 implanted Si-gate PMOSFET under γ-irradiation;optimum BF+2 implantation dose in the hardened Si-Gate PMOSFET ranges from 5×1014—2×1015cm-2;F atoms distributed at SiO2/Si interface,which suppress the oxide-trap charges and interface-trap charges produced under γ-irradiation,may be the main origin of BF+2-implanted and hardened Si-gate PMOSFET.
1999, 48 (12): 2304-2307.
doi: 10.7498/aps.48.2304
Abstract +
The effects of shock waves on the structure of amorphous alloys FeBSi,FeMoBSi have been studied by means of X-ray diffraction;the lattice constant of the crystal phase α-Fe was measured.It has been found that its lattice constant becomes shorter than that of pure iron.The experimental results are fitted with theory by using the pair potenial model.It is certain that formation of B-substituted solid solution and omission solid solution would lead to a shorter lattice constant.
1999, 48 (12): 2308-2313.
doi: 10.7498/aps.48.2308
Abstract +
By using a simple model of soliton-antisoliton pairs to simulate the quantum lattice fluctuations in one-dimensional organic polymers, in which the subgap absorption results from the transitions between the lowest unoccupied and the highest occupied levels off the conduction and valence bands, respectively, in the soliton-antisoliton excitations. There is no gap in the absorption. Our result indicates clearly that the nondegeneracy of ground-states suppresses the quantum fluctuations, so that the subgap absorption is reduced and there is a related clear onset in the absorption spectrum of nondegenerate polymers, which is in agreement with experiments.
1999, 48 (12): 2314-2319.
doi: 10.7498/aps.48.2314
Abstract +
We present the numerical calculation of the model of aluminum flyer-vacuum-target with high power laser driving.The results show that the parameters of laser and target's structure have great effects on the state of flyer and the character of shock-waves in the target.If we select the parameters of laser and target's structure reasonably, we can achieve approximately symmetric impact between flyer and target;moreover,the shock-wave in the target has a stable area with a certain spatial width.So,if we choose the three-step-target with a suitable thickness,we can approach an absolute measurement of equation-of-state.
1999, 48 (12): 2320-2326.
doi: 10.7498/aps.48.2320
Abstract +
The epitaxial growth crystal structure and magnetism of Co100-xMnx alloys grown on GaAs(001) substrate have been studied by using reflection high energy electron diffraction,X-ray diffraction and surface magneto-optic Kerr effect. For 0100-xMnx alloys.They show strong ferromagnetism.For 42100-xMnx alloy exists in bodycentered cubic(bcc)and face-centered cubic(fcc)phases respectively,and the coexistence of the bcc and fcc structures is observed in the middle stage.It is proved by using wedge samples that only the bcc phase contributes to the ferromagnetism.For x>78,the epitaxial alloys have fcc structure and show no Ferromagnetism.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
1999, 48 (12): 2327-2333.
doi: 10.7498/aps.48.2327
Abstract +
In this paper we simulate the phenomenon “field-induced charge generation” observed in polymers by means of molecular dynamics, and present the time-dependent evolution of bond structure and charge distribution of the polymer chain. The relaxation time of the transformation of one exciton into a couple of polarons is also determined.
1999, 48 (12): 2334-2342.
doi: 10.7498/aps.48.2334
Abstract +
In this paper, it is reported that the Sn ions (200keV, 6×1016 and 1×1017ion/cm2) were implanted at room temperature into specimens of lead telluride. By making use of electric and thermal measurements, X-ray diffraction and X-ray photoelectron spectroscopy, we have studied the effects of implantation on the thermoelectric properties and the structure of implanted layer of lead telluride.
1999, 48 (12): 2343-2348.
doi: 10.7498/aps.48.2343
Abstract +
A quantization scheme for a R(t)LC mesoscopic circuit has been given,in which we employ the canonical transformation and Feynman's path integral method.The charge and generalized current quantum fluctuation of the circuit are discussed,and the uncertainty relation of charge and generalized current has also been shown.
1999, 48 (12): 2349-2356.
doi: 10.7498/aps.48.2349
Abstract +
The paper presents that the plasma frequency ωp of semiconductor films are regulated by the way of changing its doping concentration,which lead to high transmission.Zone of the film shift visible spectral rang Vω,the semiconductor film is combined with the metal which thinness induced transmission frequency ωg locate in the edge of ultra violet range to compose the excellent D/M spectral transmission and reflection film systems.Besides,it is also necessary to select the most suitable combination of the thickness between the semiconductor and the metal films for forming the excellent transparent heat insulation film.
1999, 48 (12): 2357-2363.
doi: 10.7498/aps.48.2357
Abstract +
Taking into account the rough interface scattering and magnetic scattering effects of the ferromagnet layer in the normal metal-ferromagnet insulator-d wave superconductor junctions,using Bogoliubov-de Gennes equations and Blonder-Tinkham-Klapwijk model,we have calculated the differential conductance.It is found that:1)both rough interface scattering and magnetic scattering can suppress the zero-bias conductance peaks(ZBCP),in which the magnetic scattering can lead to a splitting of the ZBCP but the rough interface can resist the splitting,and the ZBCP will evolve some dips due to two higher potentials of the scattering;2)the subgap resonances in the differential conductance are predicted under the condition of a ferromagnet layer located at a distance several times larger than the coherence length from the superconductor interface.
1999, 48 (12): 2364-2368.
doi: 10.7498/aps.48.2364
Abstract +
Based on the theory of r.f. SQUID,the principle for a phase-sensitive test of the symmetry of the order parameter in high-temperature superconductors by using r.f. SQUID in the inductive mode(β≤1,without the limit of β1)is given.We also investigate (calculating and discussing) a system with β=0.7 and offer the range of its r.f. bias flux,under which the r.f. SQUID can be used to probe the phase of the pairing state.
1999, 48 (12): 2369-2376.
doi: 10.7498/aps.48.2369
Abstract +
The magnetism of Co1-xMnx alloys strongly depends on their structure and the Mn content.An ab initio linearized augmented plane wave (LAPW)method has been carried out to provide the electronic and magnetic structures for the fcc and bcc Co1-xMnx alloys with x=0.00,0.25,0.50,0.75 and 1.00. By increasing the Mn content,the magnetism of fcc Co1-xMnx alloys changes from ferromagnetism to ferrimagnetism,finally to antiferromagnetism;on the other hand, the magnetism of bcc Co1-xMnx alloys changes from ferromagnetism to ferrimagnetism.A good agreement is reached between out calculations and the previous experimental results.
INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
1999, 48 (12): 2377-2381.
doi: 10.7498/aps.48.2377
Abstract +
The optical nonlinearity and the thermal stability of disperse red 1 (DR1)-doped PMMA/silica-gel films were investigated. It was found that the optical second-order nonlinear thermal-stability of DR1-doped PMMA/silica-gel hybrid was enhanced. We have also studied the factors that affect the second-order nonlinear intensity of the system.
1999, 48 (12): 2382-2388.
doi: 10.7498/aps.48.2382
Abstract +
Micro-Raman analyses were carried out to investigate the micro-structure of cross section for diamond films prepared by hot-filament chemical vapor deposition.The variation of Raman peak feature with position was recognized as the difference of micro-structure in the film.The presence of broad band and high background intensity near the substrate surface was attributed to the amorphous carbon synthesized in the nucleation process of diamond film.The reduction of sp3-bond structure in the amorphous carbon phase was used to account for the observation of the 1200—1600cm-1 band intensity declination as the increase of film thickness.From the Raman feature it was shown that the sp2-bond structure and the graphitic phase decreased slowly,compared with the bond structure in the growth process of the film.The micro-Raman spectroscopy obtained by scanning parallel to the surface of the film showed the structure and composition difference between the diamond grain and the grain boundary.
