A Time-Transformed Leapfrog Scheme

We present a time-transformed leapfrog scheme combined with the extrapolation method to construct an integrator for orbits in N-body systems with large mass ratios. The basic idea can be used to transform any second-order differential equation into a form which may allow more efficient numerical integration. When applied to gravitating few-body systems this formulation permits extremely close two-body encounters to be considered without significant loss of accuracy. The new scheme has been implemented in a direct N-body code for simulations of super-massive binaries in galactic nuclei. In this context relativistic effects may also be included.     

Infinitesimal orbits around lagrange points in the elliptic,restricted three-body problem

This study presents a method of obtaining asymptotic approximations for motions near a Lagrange point in the planar, elliptic, restricted three-body problem by using a von Zeipel-type method. The calculations are carried out for a second-order escape solution in the proximity of the equilateral Lagrange point, L ₄, where the primaries' orbital eccentricity is taken as the small parameter .     

搅拌桩复合地基平面模拟的简化方法探讨

水泥土搅拌桩(DMM)在高速公路工程中得到广泛应用,人们也希望能对该复合地基在路堤荷载下的地基的变形深入了解,其数值分析是一种重要的方法。但是,采用三维有限元进行数值模拟在高速公路工程中容易造成数组过大,计算时间并且收敛性比较差,因此把三维问题简化为二维问题是众望所归。在把三维问题简化二维平面问题简化计算时,最重要的是参数的折减。基于水泥土搅拌桩复合地基的特性,结合理论分析提出了一种参数折减的方法。并依据连盐高速公路实测的数据验证了该参数简化方法的可行性。     

一种基于Ohta-Okamoto签名的门限群签名方案

在修改的Ohta_Okamoto数字签名方案基础上,设计出了一个新的(t,n)门限签名方案。该方案具有可验证性和防止内部成员合谋攻击;而且验证者在验证群签名的有效性计算的复杂性与一般个人签名方案一样。该方案的安全性是基于大整数的因式分解,因此在计算上是安全的。     

Burial and exhumation of the Hoh Xil Basin,northern Tibetan Plateau: Constraints from detrital (U-Th)/He ages

The uplift and associated exhumation of the Tibetan Plateau has been widely considered a key control of Cenozoic global cooling. The south-central parts of this plateau experienced rapid exhumation during the Cretaceous–Palaeocene periods. When and how the northern part was exhumed, however, remains controversial. The Hoh Xil Basin (HXB) is the largest late Cretaceous–Cenozoic sedimentary basin in the northern part, and it preserves the archives of the exhumation history. We present detrital apatite and zircon (U-Th)/He data from late Cretaceous–Cenozoic sedimentary rocks of the western and eastern HXB. These data, combined with regional geological constraints and interpreted with inverse and forward model of sediment deposition and burial reheating, suggest that the occurrence of ca. 4–2.7 km and ca. 4–2.3 km of vertical exhumation initiated at ca. 30–25 Ma and 40–35 Ma in the eastern and western HXB respectively. The initial differential exhumation of the eastern HXB and the western HXB might be controlled by the oblique subduction of the Qaidam block beneath the HXB. The initial exhumation timing in the northern Tibetan Plateau is younger than that in the south-central parts. This reveals an episodic exhumation of the Tibetan Plateau compared to models of synchronous Miocene exhumation of the entire plateau and the early Eocene exhumation of the northern Tibetan Plateau shortly after the India–Asia collision. One possible mechanism to account for outward growth is crustal shortening. A simple model of uplift and exhumation would predict a maximum of 0.8 km of surface uplift after upper crustal shortening during 30–27 Ma, which is insufficient to explain the high elevations currently observed. One way to increase elevation without changing exhumation rates and to decouple uplift from upper crustal shortening is through the combined effects of continental subduction, mantle lithosphere removal and magmatic inflation.     

一类非线性二阶常微分方程解的多重性

考虑一类二阶非线性常微分方程的边值问题（p（t）u′）′＋h（t）f（u）=0，0＜t＜1和u（0）=u（1）=0。通过引入f（s）／s在∞与0处的极限值，并运用打靶法和相应的Sturm比较定理得到解的多重性定理，推广有关文献中的许多重要结果。     

Estimating gambling venue catchments for impact assessment using a calibrated gravity model

Gambling using electronic gaming machines (EGMs) has emerged as a significant public health issue. While social impact assessments are required prior to the granting of new gaming machine licenses in Australia, there are a few established techniques for estimating the spatial distribution of a venue’s clientele. To this end, we calibrated a Huff model of gambling venue catchments based on a geocoded postal survey (n = 7040). We investigated the impact of different venue attractiveness measures, distance measures, distance decay functions, levels of spatial aggregation and venue types on model fit and results. We then compared model estimates for different behavioural subgroups. Our calibrated spatial model is a significant improvement on previously published models, increasing R² from 0.23 to 0.64. Venue catchments differ radically in size and intensity. As different population subgroups are attracted to different venues, there is no single best index of venue attractiveness applicable to all subpopulations. The calibrated Huff model represents a useful regulatory tool for predicting the extent and composition of gambling venue catchments. It may assist in decision-making with regard to new license applications and evaluating the impact of health interventions such as mandated reductions in EGM numbers. Our calibrated parameters may be used to improve model accuracy in other jurisdictions.     

日本海洋环境问题的社会学研究动向

日本学术界已经注意到,各种环境问题中,海洋环境问题是最难解决的,棘手的原因有技术层面的问题,而更多的则是社会层面的问题。因此,将社会学引入海洋环境问题的研究是十分必要的。目前阶段,日本海洋环境问题的社会学研究在海洋观教育的基本脉络之下,分成海岸带、"森林?河流?海洋的共生"、潮间带、海洋漂浮垃圾等专题研究动向,而这些研究动向之所以形成又是与日本海洋立国的需要有着必然的联系与规律。海洋环境问题的研究是21世纪一个热点领域,有必要引进海洋国家日本关于多元化海洋环境问题与社会问题的观念和研究模式,在国际比较研究的基础上,进行中国的海洋环境社会学学科建设。     

天津市地震前兆台网的运行监控与维护管理

介绍天津市地震前兆台网的基本概况以及前兆台网部的职责任务;阐述仪器设备运行监控、观测数据质量监控的方式与方法;总结在仪器设备、技术系统维护过程中解决的一些关键技术问题;最后提出了关于仪器和软件系统的一些问题与建议。