Heterogeneous network with distance dependent connectivity

We investigate a network model based on an infinite regular square lattice embedded in the Euclidean plane where the node connection probability is given by the geometrical distance of nodes. We show that the degree distribution in the basic model is sharply peaked around its mean value. Since the model was originally developed to mimic the social network of acquaintances, to broaden the degree distribution we propose its generalization. We show that when heterogeneity is introduced to the model, it is possible to obtain fat tails of the degree distribution. Meanwhile, the small-world phenomenon present in the basic model is not affected. To support our claims, both analytical and numerical results are obtained.     

正弦条码在远距高程定位中的应用

研究了正弦条码利用相位对位移进行编解码的原理及其在远距高程定位中的应用。基于单正弦条码,分析了条码宽度幅值、数字频率及成像个数对傅里叶法求解相位误差范围的影响,指出双正弦条码和三正弦条码相对于单正弦条码的实用性,并给出相应定位算法流程图。在成像器件与标尺成不同距离时利用三正弦条码尺进行距离和高度测量,结果表明,测量精度随距离增大而降低,距离为最小约39m和最大约62m时,距离测量精度分别为2mm和27mm;高度测量精度分别为0.03mm和0.07mm。     

On the critical distance in heavy-ion collisions

An analytical expression is obtained for the electron energy term by solving a two-center Dirac problem. This expression has the correct asymptotic form in two limiting cases — the Popov approximation and the nonrelativistic problem. Zh. Tekh. Fiz. 69, 135–137 (August 1999)     

Vignetting in electro-optical distance meters

Vignetting in the optical system of an electro-optical distance meter is described, and the impact of the measuring conditions is dealt with. The method of analysis, involving numerical calculations, is given and the results for three typical cases are shown.     

The O-H distance in ice

The thermodynamic properties of normal and para-hydrogen are computed from multiple time-step path integral hybrid Monte Carlo (PIHMC) simulations. Four different isotropic pair potentials are evaluated by comparing simulation results with experimental data. The Silvera–Goldman potential is found to be the most accurate of the potentials tested for computing the density and internal energy of fluid hydrogen. Using the Silvera–Goldman potential, simulation and experimental data are compared on isobars ranging from 0.1 to 100 MPa and for temperatures from 18 to 300 K. The Gibbs free energy is calculated from the PIHMC simulations by an adaptation of Widom's particle insertion technique to a path integral fluid. A new method is developed for computing phase equilibria for quantum fluids directly by combining PIHMC with the Gibbs ensemble technique. This Gibbs–PIHMC method is used to calculate the vapour–liquid phase diagram of hydrogen from simulations. Agreement with experimental data is good.     

Short distance non-perturbative effects of large distance modified gravity

In a model of large distance modified gravity we compare the non-perturbative Schwarzschild solution of [G. Gabadadze, A. Iglesias, Phys. Rev. D 72 (2005) 084024, hep-th/0407049] to approximate solutions obtained previously. In the regions where there is a good qualitative agreement between the two, the non-perturbative solution yields effects that could have observational significance. These effects reduce, by a factor of a few, the predictions for the additional precession of the orbits in the Solar system, still rendering them in an observationally interesting range. The very same effects lead to a mild anomalous scaling of the additional scale-invariant precession rate found by Lue and Starkman.     

Cepheid distance to the virgo cluster

HST data on Cepheid variables in one Virgo Cluster spiral galaxy is re-analyzed, taking into account flux-limited incompleteness in the sample and calibration of the period-luminosity relation in the relevant period range. Distance to the Virgo Cluster is estimated to be 19.6 ± 1.7 (random) ± 2.6 (systematic) Mpc.     

Matrix versions of the Hellinger distance

Letters in Mathematical Physics - On the space of positive definite matrices, we consider distance functions of the form $$d(A,B)=\left[ \mathrm{tr}\mathcal {A}(A,B)-\mathrm{tr}\mathcal...     

双棱镜干涉实验中距离参数的分析

分析了双棱镜干涉实验中各光学元件间距离参数的联系及对波长测量误差的影响,在此基础上,对如何适当选择距离参数以提高实验效率提出建议.     

Ultrasonic system for accurate distance measurement in the air

This paper presents a system that accurately measures the distance travelled by ultrasound waves through the air. The simple design of the system and its obtained accuracy provide a tool for non-contact distance measurements required in the laser’s optical system that investigates the surface of the eyeball.     

Island distance in one-dimensional epitaxial growth

The typical island distance in submonolayer epitaxial growth depends on the growth conditions via an exponent . This exponent is known to depend on the substrate dimensionality, the dimension of the islands, and the size i^* of the critical nucleus for island formation. In this paper we study the dependence of on i^* in one-dimensional epitaxial growth. We derive that for and confirm this result by computer simulations. Received: 26 May 1998 / Accepted: 23 June 1998     

Rotational-resonance distance measurements in multi-spin systems

It is demonstrated that internuclear distances can be evaluated from rotational-resonance (RR) experiments in uniformly (13)C-labelled compounds. The errors in the obtained distances are less than 10% without the need to know any parameters of the spin system except the isotropic chemical shifts of all spins. We describe the multi-spin system with a simple fictitious spin-1/2 model. The influence of the couplings to the passive spins (J and dipolar coupling) is described by an empirical constant offset from the rotational-resonance condition. Using simulated data for a three-spin system, we show that the two-spin model describes the rotational-resonance transfer curves well as long as none of the passive spins is close to a rotational-resonance condition with one of the active spins. The usability of the two-spin model is demonstrated experimentally using a sample of acetylcholine perchlorate with labelling schemes of various levels of complexity. Doubly-, triply-, and fully labelled compounds lead to strongly varying RR polarization-transfer curves but the evaluated distances using the two-spin model are identical within the expected error limits and coincide with the distance from the X-ray structure. Rotational-resonance distance measurements in fully labelled compounds allow, in particular, the measurement of weak couplings in the presence of strong couplings.     

Shock formation distance in real air

A simple derivation of the shock formation distance in spherically symmetric, unsteady, non-equilibrium flow is presented. The one-dimensional unsteady flow and the ideal gas flows emerge as special cases. The results are applied to atmospheric air and the ambiguity and limitations of the shock formation concept are discussed.     

On the average distance between particles in the two-dimensional two-component plasma

The asymptotic forms of the average distance of the closest particle to a fixed positive charge, and of the closest particle to the origin, are obtained for the two-dimensional two-component plasma in the low-density limit. The asymptotic forms of the average areas of the corresponding disks formed by the closest particle are also derived. These results are verified at a special coupling where exact results are available.Laboratoire Associé au Centre National de la Recherche Scientifique.     

Dependence of the exchange splitting in excitons on the interatomic distance

The exchange splitting observed in excitons depends exponentially on the interatomic distance of the cation and anion of the compound.     

相位激光测距与外差干涉相结合的绝对距离测量研究

 为了克服一般绝对距离测量方法量程和精度不能同时满足的问题,提出一种相位激光测距与外差干涉相结合的绝对距离测量方案。该方案使用相位激光测距技术进行粗测,双纵模He-Ne激光器外差干涉测长技术进行精测,保证两者结合的单值性。建立测量系统,对方案的可行性进行了实验验证,并对影响系统稳定性的因素进行了分析。与双频激光干涉仪的比对结果表明：测量标准差优于1mm,可以满足一些大尺寸的测量精度要求。     

Proof of expansion of the reciprocal distance in spheroidal coordinates

A concise proof is given for the expansion of the reciprocal distance between two points in spheroidal harmonics. The proof is given for an oblate and a prolate spheroid.