Effect of subglacial shear on geomechanical properties of glaciated soils

Continental glaciers covered as much as thirty percent of the present-day inhabited earth during the Quaternary period. Traditionally, one-dimensional consolidation has been considered as the main process of formation for the soils deposited during glaciation. One of the outcomes of accepting one-dimensional consolidation as the main process of formation is that the geomechanical properties of soil in a horizontal plane are isotropic (known as cross-anisotropy). Recent measurements of subglacial pore pressure and preconsolidation pressure profile have indicated that this might not be the case. The role of subglacial shear action has probably been long neglected. The main objective of this research is to investigate the effects of subglacial shearing on the geomechanical properties of glaciated soils. Recent research has found evidence of horizontal property anisotropy associated with the direction of the ice-sheet movement. A testing program was thus proposed to explore the relationship between the anisotropy of property and the direction of past glacier movement. The program involves several fundamental engineering parameters of soils. These parameters together with the corresponding test methods are as follows: (i) Conventional oedometer test – yield stress anisotropy; (ii) Oedometer test with lateral stress measurement – stiffness anisotropy; (iii) Load cell pressuremeter (LCPM) test – in situ stress anisotropy. The physical meaning of yield stress determined by conventional oedometer tests was interpreted as the critical state of structural collapse. The literature review and an experimental study on kaolin samples with a known stress history suggested that yield stress possesses certain dependency on the sampling direction. The anisotropy of yield stress for Battleford till from Birsay, Saskatchewan was also explored by testing directional oedometer samples. In addition, the anisotropy of stiffness was also investigated using a newly developed lateral stress oedometer that is capable of independent measurement of horizontal stresses at three different points with angles of 120 degrees. Preliminary evidence of a correlation between the direction of maximum stiffness in a horizontal plane and the known direction of glacial shear was observed. The correlation between the direction of maximum yield stress and known direction of glaciation was rather poor. Anisotropy of in situ stresses was investigated by conducting LCPM tests in Pot clay in the Netherlands. Based on the LCPM test results, it was concluded that the evidence of a correlation between the anisotropy of in situ stress and known direction of glacial advance is still rather obscure. Although both the laboratory studies and field studies cannot sufficiently confirm the existence of lateral anisotropy of geomechanical properties and its relationship to the direction of the Quaternary ice-sheet movement, the effects of subglacial shearing should not be neglected in assessing the geotechnical properties of glaciated soils. In practice, it is usually found that the preconsolidation pressure profile does not follow the gravitational line as predicted by the one-dimensional consolidation theory and its magnitude is not compatible with the measured effective pressure values at the base of the glacier. It has been suggested that changes in seepage gradient (upward or downward) are responsible for the deviation of preconsolidation pressure profile away from the gravitational line. In this thesis, a new glacial process model – consolidation coupled shearing – was proposed. This model is based on the framework of traditional soil mechanics (critical state theory, Modified Cam-clay model and one-dimensional consolidation theory) and is consistent with the general geological and glaciological evidences. This model may provide an alternative explanation for the preconsolidation pressure patterns generally observed in practice. It can also be combined with groundwater flow characteristics to explain the diversity of the preconsolidation consolidation patterns. The proposed model was used successfully to obtain the preconsolidation pressure profile observed in Battleford till at Birsay and the subglacial shear-softening phenomenon

Image Segmentation of Activated Sludge Phase Contrast Images Using Phase Stretch Transform

[[abstract]]Activated sludge (AS) is a biological treatment process that is employed in wastewater treatment plants. Filamentous bacteria in AS plays an important role in the settling ability of the sludge. Proper settling of the sludge is essential for normal functionality of the wastewater plants, where filamentous bulking is always a persistent problem preventing sludge from settling. The performance of AS plants is conventionally monitored by physico-chemical procedures. An alternative way of monitoring the AS in wastewater treatment process is to use image processing and analysis. Good performance of the image segmentation algorithms is important to quantify flocs and filaments in AS. In this article, an algorithm is proposed to perform segmentation of filaments in the phase contrast images using phase stretch transform. Different values of strength (S) and warp (W) are tested to obtain optimum segmentation results and decrease the halo and shade-off artefacts encountered in phase contrast microscopy. The performance of the algorithm is assessed using DICE coefficient, accuracy, false positive rate (FPR), false negative rate (FNR) and Rand index (RI). Sixty-one gold approximations of ground truth images were manually prepared to assess the segmentation results. Thirty-two of them were acquired at 10× magnification and 29 of them were acquired at 20× magnification. The proposed algorithm exhibits better segmentation performance with an average DICE coefficient equal to 52.25%, accuracy 99.74%, FNR 41.8% and FPR 0.14% and RI 99.49%, based on 61 images.[[notice]]補正完

Multifunctional Bracts in the Dove Tree Davidia involucrata (Nyssaceae:Cornales)

Although there has been much experimental work on floral traits that are under selection from mutualists and antagonists, selection by abiotic environmental factors on flowers has been largely ignored. Here we test whether pollen susceptibility to rain damage could have played a role in the evolution of the reproductive architecture of Davidia involucrata, an endemic in the mountains of western China. Flowers in this tree species lack a perianth and are arranged in capitula surrounded by large (up to 10 cm#5 cm) bracts that at anthesis turn from green to white, losing their photosynthetic capability. Flowers are nectarless, and pollen grains are presented on the recurved anther walls for 5–7 days. Flower visitors, and likely pollinators, were mainly pollen-collecting bees from the genera Apis, Xylocopa, Halictus, and Lasioglossum. Capitula with natural or white paper bracts attracted significantly more bees per hour than capitula that had their bracts removed or replaced by green paper. Experimental immersion of pollen grains in water resulted in rapid loss of viability, and capitula with bracts lost less pollen to rain than did capitula that had their bracts removed, suggesting that the bracts protect the pollen from rain damage as well as attracting pollinators

Hui-neng’s Wisdom of Spiritual Liberation

Hui-neng developed the Buddhist thought of liberation and constructed the theory of spiritual liberation with Chinese characteristics Hui-neng s theory of spiritual liberation is a kind of life wisdom which aims to make people free from various afflictions and realize the freedom of the spir it In order to achieve this goal he explored the causes of afflictions found the ways to liberate people from afflictions According to his view all afflictions psychological problems originate from evils and deviations especially greed Tan hatred Chen delusio n Chi that are the three poison of consciousness called by Buddhism Because the roots of evils and deviations are giving r ise to thoughts Dongnian and arising in one s own mind Qi-xin the best way to free from any afflictions is no-thought Wu-nian no-dwelling Wu-zhu no-mark Wu-xiang which are able to make people s mind have no impediment so that the spirit will be at easy or lightheartednes

The first Chinese student space shuttle getaway special program

The first Chinese Getaway Special program is described. Program organization, the student proposal evaluation procedure, and the objectives of some of the finalist's experiments are covered. The two experiments selected for eventual flight on the space shuttle are described in detail. These include: (1) the control of debris in the cabin of the space shuttle; and (2) the solidification of two immiscible liquids in space