Impact of Gas Adsorption Induced Coal Matrix Damage on the Evolution of Coal Permeability

It has been widely reported that coal permeability can change from reduction to enhancement due to gas adsorption even under the constant effective stress condition, which is apparently inconsistent with the classic theoretical solutions. This study addresses this inconsistency through explicit simulations of the dynamic interactions between coal matrix swelling/shrinking induced damage and fracture aperture alteration, and translations of these interactions to permeability evolution under the constant effective stress condition. We develop a coupled coal–gas interaction model that incorporates the material heterogeneity and damage evolution of coal, which allows us to couple the progressive development of damage zone with gas adsorption processes within the coal matrix. For the case of constant effective stress, coal permeability changes from reduction to enhancement while the damage zone within the coal matrix develops from the fracture wall to further inside the matrix. As the peak Langmuir strain is approached, the decrease of permeability halts and permeability increases with pressure. The transition of permeability reduction to permeability enhancement during gas adsorption, which may be closely related to the damage zone development in coal matrix, is controlled by coal heterogeneity, external boundary condition, and adsorption-induced swelling.     

Simulating the moderating effect of a lake on downwind temperatures

A steady-state, two-dimensional numerical model is used to simulate air temperatures and humidity downwind of a lake at night. Thermal effects of the lake were modelled for the case of moderate and low surface winds under the cold-air advective conditions that occur following the passage of a cold front. Surface temperatures were found to be in good agreement with observations. A comparison of model results with thermal imagery indicated the model successfully predicts the downwind distance for which thermal effects due to the lake are significant.     

The measurement and extraction of the <nu>6 atmospheric emission band of CFC-12 from interfering emission features

Ground-based thermal emission measurements of the zenith sky have been made at Peterborough, Ontario since January 1993. In this paper, the measurement of the ₆ band of atmospheric CFC-12, an important greenhouse gas, is presented for a cold, clear day in January 1994. A spectrum of the non-CFC-12 emission features has been simulated using the FASCD3P radiation code and measured radiosonde profiles of temperature, pressure and humidity. This has enabled a satisfactory subtraction of the interfering emission features from the CFC-12 emission spectrum. A comparison of the observed and simulated ₆-bands of CFC-12 shows good agreement at all frequencies of emission. From these spectra the total downward greenhouse radiative flux from the CFC-12 ₆ emission based for a very cold day has been estimated to be 0.27 W m⁻²±10%.     

Types of rural out-migration in Turkey

An analysis of changes in migration patterns since World War II between inner Anatolia and eastern Anatolia in Turkey is presented. Four periods are distinguished, the exploratory period until 1950, seasonal migration until 1960, mass migration up to the present, and marriage migration from 1975 to the present. The linkages between previous and potential migrants are noted. (SUMMARY IN ENG)     

Geoeffective Disturbances in the Solar Wind near the Solar Activity Minimum according to the Data of a Two-year Series of Observations of Interplanetary Scintillations with the BSA LPI Radio Telescope

Astronomy Reports - A joint analysis of the monitoring data of interplanetary scintillations with solar and geophysical data showed that at the descending phase of the 24 solar activity cycle, the...     

青藏高原东北部降尘通量及粒度特征分析

青藏高原东北缘是柴达木沙尘暴东移的必经之道和沉降区,对青藏高原东北部降尘时空分异特征进行分析,有助于认识青藏高原区域粉尘输送的现代过程和机制。2013年12月至2015年5月分别在青海湖小泊湖(XBH)、西宁多巴(DB)、西宁青海师大科技楼顶(KJLD)设置降尘缸,进行湿法收集。对其降尘通量和粒度特征进行了时空分异特征分析,结果显示,1)西宁地区2014年降尘通量为442~542 g/m~2·a,青海湖XBH采集点指示的2014年降尘通量为415 g/m~2·a,降尘通量年际变化较大,各站点降尘通量季节变化趋势一致,降尘主要集中在冬春季,夏季降尘通量最低;2)各站点降尘粒度组成特征非常相似,以粉砂为主(4~63μm),西宁地区尘暴与非尘暴降尘粒度频率曲线呈近似正态分布,尘暴期间降尘粒径较非尘暴时段大;3)XBH、DB和KJLD 3点所有样品平均粒径分别为37μm、34μm和31μm,中值粒径分别为31μm、27μm和26μm;对比低海拔兰州尘暴粒径特征,发现降尘粒径存在一定的海拔依赖性,即粒度随海拔增高逐渐变粗。     

Land use change and its ecological effect in Qian'an County of Jilin Province

Based on GIS and statistical methods, with the help of searching historical literatures and calculating the landscape indices, the land use changes of Qian'an County in both spatial and temporal aspects from 1945 to 1996 has been analyzed in this paper. And the driving forces of land use changes and their ecological effects are discussed too. The main findings of this study are as follows: (1) Land use changed greatly in Qian'an during 1945-1996, characterized by a decrease in grassland, wetland and water bodies, and an increase in cultivated land, saline-alkali land, and the land for housing and other construction purposes. Grassland decreased by 175,828.66 ha, and cultivated land increased by 102,137.23 ha over the half century. Accordingly, the main landscape type changed from a steppe landscape to a managed agricultural ecosystem. (2) Results of correlation analysis show that the land use change in the study area was mainly driven by the socioeconomic factors.　(3) The ecological effects of land use change in the area are characterized by serious salinization, degression of soil fertility and the weakening of landscape suitability.     

InSAR用于南极测图的可行性研究

利用1996年ERS 1/2tandem方式的雷达影像数据进行了生成Grove山数字高程模型的试验研究,并与实测的DEM进行比较分析,论证了利用InSAR技术进行南极测图的可行性。试验证明,在南极研究中,InSAR是一种非常有效的手段,不仅可用于地图制图,而且在冰川动力学、冰貌环境变化等研究领域也有巨大的潜力。     

Practical Experiences with Films, Cameras and Navigation Systems

The first author commenced his experiences with aerial photography in 1945, when he joined the Royal Air Force (RAF). The aerial cameras used at that time were the Williamson F24 and F52, with Ilford HP3 and FP3 panchromatic films. Subsequently the Williamson F95 camera was tested against the USAF Sonne 11 camera. During his final years in the RAF, a variety of film types was employed: colour, monochrome infra-red and false colour infra-red. Additional experience was gained when the author was employed by the International Training Centre (ITC), The Netherlands and he saw the further development of the air camera from the Wild RC8 and Zeiss (Oberkochen) RMK 15/23 to the Wild RC20, Zeiss (Jena) LMK and Zeiss (Oberkochen) RMK TOP. He predicts that the future lies with digital cameras.
The second author started working with aerial photography in the 1950s. Details are given of cameras, visual navigation sights and survey aircraft dating from that period. Overseas operations, carried out mainly by Hunting Surveys and Fairey Surveys, posed particular problems because the majority of the work there was undertaken without the aid of existing maps. The introduction of external navigation systems is described, from the Decca ship navigation system, through the GNS-200 VLF/Omega low frequency radio system to INS, the Inertial Navigation System. The author later joined the ITC, which enabled him to participate in trials of the Computer-controlled Photo Navigation System. Eventually practical experience was gained with differential GPS, particularly in countries in southeast Asia. Aerial photography currently appears to benefit less from financial investment than the photographic, aviation and survey industries. However, the satisfaction of making a significant contribution to major overseas development projects outweighs the frustration of lack of acceptance of plans for the future of the air survey industry.