Microlensing of broad absorption line quasars

The physical nature of the material responsible for the high-velocity broad absorption line (BAL) features seen in a small fraction of quasar spectra has been the subject of debate since their discovery. This has been especially compounded by the lack of observational probes of the absorbing region. In this paper we examine the role of 'microlenses' in external galaxies in the observed variability in the profiles of BALs in multiply imaged quasars. Utilizing realistic models for both the BAL region and the action of an ensemble of microlensing masses, we demonstrate that stars at cosmological distances can provide an important probe of the physical state and structure of material at the heart of these complex systems. Applying these results to the macrolensed BAL quasar system H1413+117, the observed spectral variations are readily reproduced, but without the fine-tuning requirements of earlier studies which employ more simplistic models.     

Flow in an aquifer charged with hot water from a fault zone

Many geothermal anomalies are intersected by vertical fault zones (narrow zones of fractured material with large effective permeability). These conduits are probably responsible for much of the upwelling of hot water from depth. This paper considers a shallow aquifer intersected by a vertical fault. The fluid flow in the aquifer is numerically modeled as a two-dimensional problem. It is observed that the temperature distribution in the aquifer is governed primarily by lateral flow of hot water supplied from the intersecting vertical fault and only secondarily by conduction. The numerical results also provide a possible explanation for the local temperature maxima and inversions occasionally observed in borehole measurements. The present model is an alternative to that based on mushroom-shaped isotherm distributions found in high Rayleigh number large-scale circulation cell calculations.     

9711号台风的移动路径和影响山东的特大暴雨分析

对９７１１号台风的移动路径及其造成的暴雨进行了分析。分析表明,副高外围环流在台风移动过程中有明显的引导作用;台风的移动路径和暴雨落区与正涡度轴线及高能轴线都有较好的对应关系;对流层中层变能场的分布对台风移动路径有明显的预报指示意义。     

一次弓状降雹回波区流场的反演

通过对一次典型弓状降雹回波区的流场进行反及特点分析,发现用矩不变量法反演出的回波区流场结构,与藤田关于弓状回波的概念模式非常吻合,利用该方法估测出的流场,散度场、涡度场所表现出的信息,与降雹实况是一致的,该研究可为中小尺度强天气的监测,提供高时空分辨率的流场资料。     

Dynamics of Axisymmetric Truncated Dynamo Models

An important question regarding the study of mean field dynamo models is how to make precise the nature of their underlying dynamics. This is difficult both because relatively little is known about the dynamical behaviour of infinite dimensional systems and also due to the numerical cost of studying the related partial differential equations. As a first step towards their understanding, it is useful to consider the corresponding truncated models. Here we summarise some recent results of the study of a class of truncated axisymmetric mean field dynamo models. We find conclusive evidence in these models for various types of intermittency as well as multiple attractors and final state sensitivity. We also find that the understanding of the underlying dynamics of such dynamo models requires the study of a new class of dynamical systems, referred to as the non-normal systems. Current work demonstrates that these types of systems are capable of a novel type of intermittency and also of relevance for the understanding of the full axisymmetric PDE dynamo models.     

Central Europe: Active or residual tectonic stresses

The regional stress field in the Western Alps and their northern foreland has been investigated byin situ stress determinations. More than 600 strain relief measurements were made with resistance strain gages in boreholes carried out in mines, tunnels and quarries. The stresses calculated and data obtained from other papers were used to get a detailed idea of the stress conditions in Central Europe.The measurements confirm a continuous flux of compressive stress from the Alps to the northern foreland east of the Rhinegraben. The largest stresses are observed in the Central Alps, the lowest in the Rhinegraben rift system. The horizontal stresses exceed at nearly all places the vertical ones. Evidently the excess of horizontal stress is generated by active plate tectonics in the Alps. A tectonic model to explain the observed stress pattern is presented.     

Performance of mixed and enhanced finite elements for strain localization in hypoplasticity

Displacement and mixed finite element formulations of shear localization in materials are presented. The formulations are based on hypoplastic constitutive laws for soils and the mixed enhanced treatment involving displacement, strain and stress rates as independently varied fields. Included in these formulations are the standard displacement method, the three‐field mixed formulation, the enhanced assumed strain method and the mixed enhanced strain method. Several numerical examples demonstrating the capability and performance of the different finite element formulations are presented. The numerical results are compared with available experimental data for Hostun RF sand and numerical results for Karlsruhe sand on biaxial tests. Copyright © 2011 John Wiley & Sons, Ltd.     

Importance of no‐rain measurements on the comparison of radar and rain gauge rain rate

This study evaluated four possible cases of comparing radar and rain gauge rain rate for the detection of mean‐field bias. These four cases, or detection designs, consider in this study are: (1) design 1‐uses all the data sets available, including zero radar rain rate and zero rain gauge rain rate, (2) design 2—uses the data sets of positive radar rain rate and zero or positive rain gauge rain rate, (3) design 3—uses the data sets of zero or positive radar rain rate and positive rain gauge rain rate and (4) design 4—uses the data sets of positive radar rain rate and positive rain gauge rain rate. A theoretical review of these four detection designs showed that only the design 1 causes no design bias, but designs 2, 3 and 4 can cause positive, negative and negative design biases, respectively. This theoretical result was also verified by applying these four designs to the rain rate field generated by a multi‐dimensional rain rate model, as well as to that of the Mt Gwanak radar in Korea. The results from both applications showed that especially the design 4, which is generally used for the detection of mean‐field bias of radar rain rate, causes a serious design bias; therefore, is inappropriate as a design for detecting the mean‐field bias of radar rain rate. Copyright © 2009 John Wiley & Sons, Ltd.     

The upper limit of magnetic field strength in dense stellar hadronic matter

It is shown that in strongly magnetized neutron stars, there exist upper limits of magnetic field strength, beyond which the self energies for both neutron and proton components of neutron star matter become complex in nature. As a consequence they decay within the strong interaction time scale. However, in the ultra-strong magnetic field case, when the zeroth Landau level is only occupied by protons, the system again becomes stable against strong decay.