The born-again (very late thermal pulse) scenario revisited: the mass of the remnants and implications for V4334 Sgr

We present 1D numerical simulations of the very late thermal pulse (VLTP) scenario for a wide range of remnant masses. We show that by taking into account the different possible remnant masses, the observed evolution of V4334 Sgr (a.k.a. Sakurai's object) can be reproduced within the standard 1D mixing length theory (MLT) stellar evolutionary models without the inclusion of any ad hoc reduced mixing efficiency. Our simulations hint at a consistent picture with present observations of V4334 Sgr. From energetics, and within the standard MLT approach, we show that low-mass remnants  ( M ≲ 0.6 M_⊙)  are expected to behave markedly differently from higher mass remnants  ( M ≳ 0.6 M_⊙)  in the sense that the latter remnants are not expected to expand significantly as a result of the violent H-burning that takes place during the VLTP. We also assess the discrepancy in the born-again times obtained by different authors by comparing the energy that can be liberated by H-burning during the VLTP event.     

Precise positions of Phoebe determined with CCD image-overlapping calibration

This paper presents 210 positions of Phoebe, the ninth satellite of Saturn, observed with the 1-m telescope at the Yunnan Observatory during the years 2003–2005, using a CCD image-overlapping calibration method proposed recently by Peng et al. After the observed positions of Phoebe are compared with its theoretical positions computed by the new JPL ephemerides DE405 and SAT199, the mean residuals (observed minus computed) are 0.21 and −0.05 arcsec in right ascension and declination, respectively, with a standard deviation of 0.06 arcsec.     

基于热力图数据的杭州商业综合体活力影响因素分析

为了防止商业综合体建设过剩,形成商业综合体之间的恶性竞争。本文基于微信易出行插件里面的城市热力图数据,以杭州市5个商业综合体为例,获取可以量化的热力值数据,对不同类型的商业综合体活力影响因素进行对比分析研究。研究发现：① 城市商业综合体布局密度、周边用地用途、销售模式、内部功能布局以及内部空间活力5个要素对商业综合体活力的影响最明显;② 商业综合体的高密度布局对其活力存在抑制作用,通过对比各个服务半径内的商业综合体的活力变化,发现商业综合体合理的服务半径应该大于1.0 km。商业综合体周边的居住用地、广场和公园用地对其活力具有增强作用,办公用地对商业综合体活力的影响较弱;③ 针对不同消费对象制定的不同销售模式,也会对商业综合体活力变化产生显著影响;④ 在公共活动空间相对缺乏的区域内,以零售为主且兼具城市公共活动空间的商业综合体比以主力店为主的商业综合体的活力更高,空间利用率越高的商业综合体活力也越高,商业综合体承担部分城市公共活动空间的职能对商业综合体的活力起到了提升作用。     

PLS法与隧道围岩稳定性分类

围岩稳定性是隧道工程支护设计的基本参数,采用偏最小二乘回归法,综合考虑多因变量影响因素,对隧道围岩稳定性分类进行回归建模,并取得较好效果.     

Fracture mechanics analysis of multiple cracks in anisotropic media

This paper presents a single‐domain boundary element method (BEM) for linear elastic fracture mechanics analysis in the two‐dimensional anisotropic material. In this formulation, the displacement integral equation is collocated on the un‐cracked boundary only, and the traction integral equation is collocated on one side of the crack surface only. A special crack‐tip element was introduced to capture exactly the crack‐tip behavior. A computer program with the FORTRAN language has been developed to effectively calculate the stress intensity factors of an anisotropic material. This BEM program has been verified having a good accuracy with the previous researches. Furthermore, by analyzing the different anisotropic degree cracks in a finite plate, we found that the stress intensity factors of crack tips had apparent influence by the geometry forms of cracks and media with different anisotropic degrees. Copyright © 2010 John Wiley & Sons, Ltd.     

An Individual Rural Geography

To date, only limited research has focused on the individual in rural geography compared to the importance given to the rural community. With the sociocultural turn and moral positions in rural geography, however, the individual is acquiring more relevance but encapsulated in analytical traditions of locality community and of marginal situations and people. This article synthesizes the most significant works about the individual, especially within rural geography, and its key dimensions are identified: citizenship (political and normative dimension), emotional aspects (the extraordinary moments in peoples' lives), everyday life (the relationship between the individual and the rural place), and difference and otherness (between and within others). To develop an individual rural geography, these four dimensions, which reflect different aspects of the rural individual, must be used in a complementary manner. The relevance of each dimension suggests different types of individualities in rural areas. Ultimately, this article proposes a “new humanism” in contrast with antihumanistic poststructural approaches.     

The development and analysis of quasi-linear map projections

Map projections are an essential component of coordinate systems used in applications such as surveying, topographic mapping, and engineering, and care needs to be taken to select ones that minimize distortion for each case. This article explores the selection process for near-linear features on the surface of the Earth and derives limits for the extent of a project that can be projected within specified distortion tolerances. It is then demonstrated that a multifaceted set of projections of the Earth may be used to extend this concept to the mapping of features such as highways and railways that are quasi-linear but do not exactly follow a standard geometrical line (a great circle or a small circle) on the surface of the Earth. A continuous, conformal coordinate system may be derived in such situations, extending to indefinite length and applicable over a swath of several kilometers width, but it cannot be extended to cover situations with extensive variations in height. Instead, the Snake Projection is analyzed, and it is shown that this can be used to develop continuous (non-zonal) projected coordinate systems for major engineering projects extending for hundreds of kilometers and having extensive height ranges. Examples are shown of the application to railway projects.     

中国居民食物消费碳排放时空演变趋势及其驱动机制分析

食物生产是影响温室效应气体排放的重要方面,由于食物类型不同其碳排强度存在较大的差异,因此当前中国居民食物消费快速演替必然会对生态碳环境产生重要影响。论文利用洛伦兹曲线和基尼系数,研究1997—2016年中国城乡居民食物消费在生产过程中碳排放时空演变及其主要驱动因子。主要结论如下：① 在数量上,中国居民食物消费碳排放总量和人均量整体都呈现逐渐的增长刚性,但仍属于低碳消费模式;② 在结构上,各类型食物碳排放演变呈现显著的分异态势,整体上动物性食物碳排放增长速度快于植物性食物碳排放减少速度;③ 在城乡差异上,城镇和乡村居民食物消费碳排放在数量、结构和趋势上表现出显著的城乡二元属性,但近年城乡差异表现出减缓趋势;④ 在空间上,各地食物消费碳排放呈现较显著的民族性、地域性、集聚性和中心“塌陷”的特征,碳排放密度高值主要分布在直辖市和沿海经济相对发达地区;⑤ 在驱动力上,结构演替是全国居民食物消费碳排放总量整体变化的主要驱动因素,而人口数量是各地地域空间差异分布的主要驱动因子。     

机载测雨雷达两种反演方法的优化和综合利用的模拟研究

由于机载雷达的天线不能做得太大,如果想获得一个较好的束向分辨率,就不得不使用X波段的频率,而该波段的电磁波穿过雨区时会受到衰减,直接利用视反射率进行降水反演就会产生很大的误差,因此,衰减效应必须进行校正。两种降水反演方法——立体雷达方法和双束算法,在实际的反演中各有优缺点。立体雷达方法对边界条件要求高,而双束算法在雨团中心雨强大处会有较大的误差。引入权重因子后的立体雷达方法－双束算法(综合算法)能充分发挥两种方法的优点,从而更具适用性和准确性。