Numerical and experimental studies of pressure-controlled cavity expansion in completely decomposed granite soils of Hong Kong

Compaction grouting is the injection of a viscous grout into a soil under high pressure, which then densifies the surrounding soil by reducing void space. Laboratory and field tests of compaction grouting have been carried out. In this paper, a numerical model is used to simulate the compaction grouting process with the primary purpose of investigating relationships among various control parameters, such as injection pressure, void ratio and excess pore water pressure at various radial distances from the injection point. The compaction process is treated as a cavity expansion process in the numerical simulation. The soil is modelled with an elasto-plastic Mohr–Coulomb model using the commercial finite element program ABAQUS. In addition to numerical simulations, pressure-controlled cavity expansion laboratory tests were carried out on completely decomposed granite (CDG) soil specimens. Data collected from laboratory tests are compared with the finite element simulation to validate the finite element analyses. Factors that control the compaction process, such as the coefficient of earth pressure (K), initial void ratio, number of loading cycles and effective confining pressure, are explored in the numerical simulations.     

From small sets of GPS trajectories to detailed movement profiles: quantifying personalized trip-dependent movement diversity

ABSTRACT

The ubiquity of personal sensing devices has enabled the collection of large, diverse, and fine-grained spatio-temporal datasets. These datasets facilitate numerous applications from traffic monitoring and management to location-based services. Recently, there has been an increasing interest in profiling individuals' movements for personalized services based on fine-grained trajectory data. Most approaches identify the most representative paths of a user by analyzing coarse location information, e.g., frequently visited places. However, even for trips that share the same origin and destination, individuals exhibit a variety of behaviors (e.g., a school drop detour, a brief stop at a supermarket). The ability to characterize and compare the variability of individuals' fine-grained movement behavior can greatly support location-based services and smart spatial sampling strategies. We propose a TRip DIversity Measure --TRIM – that quantifies the regularity of users' path choice between an origin and destination. TRIM effectively captures the extent of the diversity of the paths that are taken between a given origin and destination pair, and identifies users with distinct movement patterns, while facilitating the comparison of the movement behavior variations between users. Our experiments using synthetic and real datasets and across geographies show the effectiveness of our method.     

Preliminary investigation of Late Pleistocene fauna from Ryonggok Cave No. 1, Sangwon County,North Hwanghae Province,Democratic People's Republic of Korea

The investigation of a limestone cave on the Ryonggok-ri of Sangwon County, North Hwanghae Province, DPRK, has yielded many faunal remains including Late Pleistocene deer, brown bears and horses. Uranium series dating of fossil teeth yielded dates of ~72ka at the base of Layer 2 – the bone-bearing unit – and ~44ka at the top. The rich and diverse mammal remains of Ryonggok Cave No. 1 are indicative of warm and humid temperate conditions during the Late Pleistocene, and reflect the presence of both dense forests and open grassland. In addition, pollen and spores from the site include two families and 24 genera of trees, six families and a genus of grasses and herbs, and two families and six genera of ferns, corroborating the environments inferred from the faunal remains.     

闪电定位和雷达观测资料在云分析中的应用及数值试验

本文针对2016年6月山西、山东地区一次强对流活动,通过GRAPES（Global/Regional Assimilation andPrediction Enhanced System）云分析系统融合了多普勒雷达反射率三维组网拼图资料和ADTD（Active DirectoryTopology Diagrammer）闪电定位资料,对模式初始场的云水、云冰等云微物理变量进行了调整和分析,并对这次强对流过程设计了3组数值试验。结果表明:（1）云分析系统在加入雷达反射率资料以后,能在模式初始场中较准确的计算模式的初始水物质;（2）闪电定位资料转换成的替代雷达反射率对原有的雷达反射率有一定的补充作用,使模式的初始场与真实状况更接近;（3）从模式降水的角度看,在加入雷达资料以后,GRAPES云分析可以显著提高6小时以内降水的模拟效果,而闪电定位资料的加入,对中雨以上量级的降水模拟有进一步的改进作用。     

The interplay of sediment characteristics,depth, water temperature,and ocean currents shaping the biogeography of lancelets (Subphylum Cephalochordata) in the NW Pacific waters

Lancelets (or amphioxus) are often found within the soft bottom of shallow tropical and temperate seas. The present study is the first to provide a fine‐scale biogeography of five species of lancelets (Asymmetron lucayanum, Branchiostoma belcheri, Branchiostoma japonicum, Epigonichthys cultellus, and Epigonichthys maldivensis) in the NW Pacific and examine the effects of multiple environmental parameters. From multivariate analyses, the distribution and abundance patterns of lancelets were explained by a combination of factors comprising depth, temperature of the collecting month, mean temperature of the coldest month in the year, medium particle size and silt/clay ratio of the sediments. In addition, ocean currents also affect their distribution range. The major occurrence of A. lucayanum and E. maldivensis was associated with the warm Kuroshio current, but E. maldivensis exhibited higher tolerance to low salinity and low temperature, and preferred substrata of slightly larger grain size, a lower ratio of suspended sediments, and deeper water. The closely related B. belcheri and B. japonicum exhibited fine‐scale habitat differentiation, and B. japonicum was abundant along the southern coast of China, where the salinity is lower in winter because of the China Coastal Current and the substratum is composed of very coarse sand with suspended sediments. Branchiostoma belcheri occurred in low abundance and was only recorded in Northern Taiwan and the Taiwan Banks. Epigonichthys cultellus was found only at the Taiwan Banks, which had deep water, coarse sand, and a negligible amount of suspended sediments.     

Feasibility of an infrared parallax program using the Fan Mountain Tinsley reflector

Despite the continuing importance of ground-based parallax measurements, few active programs remain. Because new members of the solar neighborhood tend towards later spectral types, infrared parallax programs are particularly desirable. Therefore, the astrometric quality of the new infrared camera, FanCam, developed by the Virginia Astronomical Instrumentation Laboratory (VAIL) for the 31-in. (0.8 m) Tinsley reflector at Fan Mountain Observatory was assessed using 68 J-band exposures of an open cluster, NGC 2420, over a range of hour angles during 2005. Positions of 16 astrometric evaluation stars were measured and the repeatability of those positions was evaluated using the mean error in a single observation of unit weight. Overall, a precision of 1.3 ± 0.7 μm in x (RA) and 1.3 ± 0.8 μm in y (Dec) was attained, which corresponds to 0.04″ ± 0.02″ in each axis. Although greater precision is expected from CCDs in the visual and near-infrared, this instrument can achieve precision similar to that of the ESO NTT infrared parallax program. Therefore, measuring parallaxes in the infrared would be feasible using this equipment. If initiated, such a program could provide essential distances for brown dwarfs and very low mass stars that would contribute significantly to the solar neighborhood census.     

Validating the turbulence parameterization schemes of a numerical model using eddy dissipation rate and turbulent kinetic energy measurements in terrain-disrupted airflow

A number of turbulence parameterization schemes are available in the latest version (6.0) of the Regional Atmospheric Modelling System (RAMS). Chan in Meteorol Atmos Phys 103:145–157, (2009), studied the performance of these schemes by simulating the eddy dissipation rate (EDR) distribution in the vicinity of the Hong Kong International Airport (HKIA) and comparing with the EDR measurements of remote-sensing instruments at the airport. For the e-l (turbulent kinetic energy ? mixing length) scheme considered in that study, the asymptotic mixing length was assumed to be a constant. This assumption is changed in the present paper, a variable asymptotic mixing length is chosen and simulations of EDR fields are repeated for terrain-disrupted airflow in the vicinity of HKIA. It is found that, with a variable asymptotic mixing length, the performance of the e-l scheme is greatly improved. With suitable choice of the empirical constants in the turbulence closure, the accuracy of the EDR profile (in comparison with LIDAR and wind profiler measurements) is found to be comparable with that predicted by the Deardorff scheme. A study on the sensitivity of the simulation results to these empirical constants has also been performed. Moreover, as a follow-up of the previous study of Chan in Meteorol Atmos Phys 103:145–157, (2009), case studies have been conducted on the following issues of the model simulation of turbulence for aviation application: (a) the effect of vertical gridding on the simulation results, (b) possibility of false alarm (such as over-forecasting of EDR value) in light turbulence cases, and (c) the performance in the simulation of other turbulence intensity metric for aviation purpose, e.g. TKE.     

Hydrogeochemistry and environmental isotopes of ground water in Jeju volcanic island,Korea: implications for nitrate contamination

Ground water from springs and public supply wells was investigated for hydrochemistry and environmental isotopes of ³H, ¹⁸O and D in Jeju volcanic island, Korea. The wells are completed in a basaltic aquifer and the upper part of hydrovolcanic sedimentary formation. Nitrate contamination is conspicuous in the coastal area where most of the samples have nitrate concentrations well above 1 mg NO₃ N/l. Agricultural land use seems to have a strong influence on the distribution of nitrate in ground water. Comparison of stable isotopic compositions of precipitation and ground water show that ground water mostly originates from rainy season precipitation without significant secondary modification and that local recharge is dominant. ³H concentration of ground water ranged from nearly zero to 5 TU and is poorly correlated with vertical location of well screens. The occurrence of the ³H‐free, old ground water is due to the presence of low permeability layers near the boundary of the basaltic aquifer and the hydrovolcanic sedimentary formation, which significantly limits ground water flow from the upper basaltic aquifer. The old ground water exhibited background‐level nitrate concentrations despite high nitrate loadings, whereas young ground water had considerably higher nitrate concentrations. This correlation of ³H and nitrate concentration may be ascribed to the history of fertilizer use that has increased dramatically since the early 1960s in the island. This suggests that ³H can be used as a qualitative indicator for aquifer vulnerability to nitrate contamination. Copyright © 2005 John Wiley & Sons, Ltd.