兰渝铁路辐射带经济空间差异及其对策研究

以兰渝铁路沿线120 km范围内的主要行政单元为研究对象,选取衡量经济发展的9个指标,运用主成分分析法揭示辐射带经济差异,同时运用Geoda软件提供的空间分析方法揭示辐射带经济差异的空间分异特征。分析结果表明,辐射带经济发展水平差异显著,在地理空间上存在集聚性;铁路的重庆段为铁路经济发展的热点区,辐射带内除重庆外无二级节点城市引导经济发展,重庆的经济辐射能力随距离的增加呈现出明显的衰减效应。在此基础上分析了影响兰渝铁路辐射带经济发展的主要因素,并提出相应的发展对策。     

基于3S技术的城市辐射效应景观分析——以蓬莱市为例

本文在3S技术的支持下采用缓冲区分析,从景观和斑块两个层次对蓬莱市城市辐射效应与景观结构关系进行了研究。结果表明:在景观层次上,随着城市辐射距离的增加,景观破碎化降低。在斑块层次上,蓬莱市的城市辐射效应对果园和水浇地的影响较大,最大距离是25km;对其他斑块类型影响不大。这表明山东半岛城市化进程加剧了景观的破碎化,而且这一过程主要是通过影响果园和水浇地斑块来实现的。     

应用Penman公式对江西省太阳总辐射变化特征的探讨

利用1961～2000年赣州站、南昌站的年太阳总辐射与相关气象要素资料,结合Penman公式,运用6种计算净长波辐射的方法估算了两站的年太阳总辐射;建立了估算该地区年太阳总辐射的绝对误差权重法（Method of Absolute Errors,MAE）,并给出了适用于江西省的绝对误差权重系数,以此方法计算了江西省其他76站的年太阳总辐射;并分析了该地区年太阳总辐射的时空分布特征及其变化趋势,发现：（1）1961~2000年间,江西省大部分地区太阳总辐射在3800～4400 MJ·m-2·a-1;南部偏东地区较大,且存在有一大值中心;西部地区为江西省太阳总辐射最小的地区;（2）40年间,江西省年太阳总辐射呈明显下降趋势,每10年减少143.70 MJ·m-2。78站中,有63站的太阳总辐射的下降趋势通过了α=0.05的显著性检验,8站表现为上升趋势;江西省北部及南部地区太阳总辐射下降较大;中部地区下降相对较小,且在鄱阳湖东侧有一低值中心。     

The power of blazar jets

We estimate the power of relativistic, extragalactic jets by modelling the spectral energy distribution of a large number of blazars. We adopt a simple one-zone, homogeneous, leptonic synchrotron and inverse Compton model, taking into account seed photons originating both locally in the jet and externally. The blazars under study have an often dominant high-energy component which, if interpreted as due to inverse Compton radiation, limits the value of the magnetic field within the emission region. As a consequence, the corresponding Poynting flux cannot be energetically dominant. Also the bulk kinetic power in relativistic leptons is often smaller than the dissipated luminosity. This suggests that the typical jet should comprise an energetically dominant proton component. If there is one proton per relativistic electrons, jets radiate around 2–10 per cent of their power in high-power blazars and 3–30 per cent in less powerful BL Lacs.     

Polarization evolution accompanying the very early sharp decline of gamma-ray burst X-ray afterglows

In the synchrotron radiation model, the polarization property depends on both the configuration of the magnetic field and the geometry of the visible emitting region. Some peculiar behaviours in the X-ray afterglows of gamma-ray bursts (GRBs) observed with Swift , such as energetic flares and a plateau followed by a sharp drop, might be highly linearly polarized because the outflows powering these behaviours may be dominated by Poynting flux. The breakdown of the symmetry of the visible emitting region may also be well hidden in the peculiar X-ray data and may give rise to interesting polarization signatures. In this paper, we focus on the polarization accompanying the very early sharp decline of GRB X-ray afterglows. We show that strong polarization evolution is possible in both the high latitude emission model and the dying central engine model, which are used to interpret this sharp X-ray decline. It is thus not easy to efficiently probe the physical origin of the very early X-ray sharp decline with future polarimetry. Strong polarization evolution is also possible in the decline phase of X-ray flares and in the shallow decline phase of X-ray light curves characterized by chromatic X-ray versus optical breaks. A detector such as the X-ray Telescope (XRT), but with polarization capability, on board a satellite like Swift would be suitable for testing our predictions.     

γ-rays from binary system with energetic pulsar and Be star with aspherical wind: PSR B1259−63/SS2883

At least one massive binary system containing an energetic pulsar, PSR B1259−63/SS2883, has been recently detected in the TeV γ-rays by the HESS telescopes. These γ-rays are likely produced by particles accelerated in the vicinity of the pulsar and/or at the pulsar wind shock, in comptonization of soft radiation from the massive star. However, the process of γ-ray production in such systems can be quite complicated due to the anisotropy of the radiation field, complex structure of the pulsar wind termination shock and possible absorption of produced γ-rays which might initiate leptonic cascades. In this paper, we consider in detail all these effects. We calculate the γ-ray light curves and spectra for different geometries of the binary system PSR B1259−63/SS2883 and compare them with the TeV γ-ray observations. We conclude that the leptonic inverse-Compton model, which takes into account the complex structure of the pulsar wind shock due to the aspherical wind of the massive star, can explain the details of the observed γ-ray light curve.     

A New Approach for Estimating Kinetic Luminosity of Jet in AGNs

The Konigl inhomogeneous jet model can successfully reproduce most observational features of jets in active galactic nuclei （AGN）, when suitable physical parameters are adopted. We improve Konigl＇s calculations on the core emission from the jet with a small viewing angle θ0 - φ （φ is half opening angle of the conical jet）. The proper motion of the jet component provides a constraint on the jet kinematics. Based on the inhomogeneous jet model, we use the proper motion data of the jet component to calculate the minimal kinetic luminosity of the jet required to reproduce the core emission measured by the very-long- baseline interferometry （VLBI） for a sample of BL Lac objects. Our results show that the minimal kinetic luminosity is slightly higher than the bolometric luminosity for most sources in the sample, which implies that radiatively inefficient accretion flows （RIAFs） may be in those BL Lac objects, or/and the properties of their broad-line regions （BLRs） are significantly different from flat-spectrum radio-loud quasars.     

Time dependent monochromatic scattering of radiation in one dimensional media: Analytical and numerical solutions

In order to choose a numerical method for solving the time dependent equations of radiative transport, we obtain an exact solution for the time dependent radiation field in a one dimensional infinite medium with monochromatic, isotropic scattering for sources with an arbitrary spatial distribution and an arbitrary time variation of their power. The Lax-Wendroff method seems to be the most suitable. Because it is assumed that radiation delay is caused by the finite speed of light, the following difficulty arises when the numerical method is used: the region of variation of the variables (position τ and time t) is triangular (the inequality τ ≤ t). This difficulty is overcome by expanding the unknown functions in series in terms of small values of the time and position. By comparing the numerical and exact solutions for a point source with a given time dependence for its power and with pure scattering, the number of steps in the variables required to obtain a desired accuracy is estimated. This numerical method can be used to calculate the intensity and polarization of the radiation from sources in the early universe during epochs close to the recombination epoch. __________ Translated from Astrofizika, Vol. 51, No. 1, pp. 109–123 (February 2008).