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The coupling of heat transfer and water flow in rock fractures is a key issue to geothermal energy extraction. However, this coupling in a rough fracture has not been well studied so far. This paper will study this coupling in a rock fracture with different roughness. First, multi-scale and self-affine rough fracture are constructed through the Weierstrass–Mandelbrot function and embedded into a rock block. Its single scale trend line is also derived. Second, a roughness factor is proposed based on the standard deviation of each segment from the trend line and introduced into the governing equation of fracture flow. After coupling with heat transfer and matrix deformation, a thermal-hydro-mechanical (THM) coupling model is formulated for a rough fracture flow. Third, an analytical solution is derived through the Laplace transform and Stehfest method and used for the validation of this THM coupling model. Finally, the effects of fracture roughness and matrix deformation on heat transfer and fracture flow are numerically investigated. The simulation results indicate that the rock fracture with lower fractal dimension has higher heat transfer efficiency. The effect of fracture roughness on heat transfer is much greater than that of aperture variation induced by the shrinkage of rock matrix. [ABSTRACT FROM AUTHOR]

Previous studies ignore the evolutions of pore microstructure parameters (pore diameter fractal dimension D λ and tortuosity fractal dimension D τ p ) but these evolutions may significantly impact the gas transport during gas extraction. In order to investigate these evolutions of fractal dimension properties during gas extraction, following four aspects are studied. Firstly, surface diffusion in adsorbed multilayer is modeled for fractal shale matrix. Our new matrix permeability model considers the slip flow, Knudsen diffusion and surface diffusion. This model is verified by experimental data. Secondly, a new fracture permeability model is proposed based on fractal theory and the coupling of viscous flow and Knudsen diffusion. Thirdly, the multilayer adsorption and these permeability models are introduced into the equations of gas flow and reservoir deformation. Finally, sensitivity analysis is performed to determine the key factors on fractal dimension evolution. The results show that the multilayer adsorption can accurately describe the adsorption properties of real shale reservoir. Shale reservoir deformation and gas desorption govern the evolutions of fractal dimensions. The multilayer adsorption and adsorbed gas porosity ϕ a play an important role in the evolutions of fractal dimensions during gas extraction. The monolayer saturated adsorption volume V m is the most sensitive parameter affecting the evolution of fractal dimensions. Therefore, the effects of gas adsorption on the evolution of fractal dimensions cannot be neglected in shale reservoirs. [ABSTRACT FROM AUTHOR]

A multiple fractured shale gas reservoir is divided into three zones, namely the single-porosity zone, the dual-porosity zone, and the hydraulic fracture zone. The distributions of pore size, fracture length, and fracture aperture vary in each zone and affect shale gas productivity. This paper developed a fractal numerical model to investigate the impacts of zone fractal properties on the shale gas productivity of a multiple fractured horizontal well. In this model, a fractal permeability model was developed, in which the diameter/aperture distribution of circular/slit pores and the length of fractures all follow fractal scaling law. This numerical model was solved by finite element method within the platform of COMSOL Multiphysics and verified through the history matching of production data from the Marcellus and Barnett shale reservoirs. Finally, the effects of the fractal dimension ( D e , D l , D τ ) and the maximum diameter ( e max ) of the pores on gas productivity (measured by gas production rate and cumulative gas production) were investigated. Numerical results show that increasing the maximum pore diameter e max can enhance gas productivity, but increasing the pore diameter fractal dimension D e makes the gas productivity decrease and increasing tortuous fractal dimension D τ decreases the gas productivity, too. The length fractal dimension D l of fractures is sensitive to the gas flow in the dual-porosity zone. [ABSTRACT FROM AUTHOR]

The -delayed particle emission from the exotic nucleus Si has been studied using a detection system with silicon array and clover-type high-purity germanium (HPGe) detectors. The -delayed charged-particle spectrum and -ray spectrum were identified. The half-life of Si has been determined. A new -delayed proton branch with an energy of 3811keV was observed. The -delayed two-proton emission was confirmed. [ABSTRACT FROM AUTHOR]

Bone possesses excellent mechanical properties, which are closely related to its favorable microstructures optimized by nature through millions of years. In this work, a scanning electron microscope (SEM) was used to observe the microstructures of a shankbone. It showed that the bone is a kind of bioceramic composite consisting of hydroxyapatite layers and collagen protein matrix. The hydroxyapatite layers are further composed of long and thin hydroxyapatite sheets. The hydroxyapatite sheets in different hydroxyapatite layers distribute along different orientations, which composes a kind of intersectant microstructure. The maximum pullout force of the intersectant microstructure was investigated and compared with that of 0° microstructure with their representative models. The result indicated that the maximum pullout force of the intersectant microstructure is markedly larger than that of the 0° microstructure, which was experimentally verified. [ABSTRACT FROM AUTHOR]

The observation of scanning electron microscope (SEM) showed that Tumblebug elytra consist of almost parallel upper and lower cuticles. Both of which are a kind of chitin-fiber-reinforced composite. There is a kind of chitin-fiber-reinforced composite pillars between the upper and lower cuticles, which support and connect the upper and lower cuticles uprightly. More careful observation showed that the chitin fibers in the pillars smoothly extend to the upper and lower composite cuticles forming a kind of fiber-continuous pillar-board composite (FCPBC) structure. Based on the observation, two kinds of pillar-board composite structure specimens, respective with continuous and discontinuous glass fibers, were fabricated with molding and felting processes. The rupture strengths of the two kinds of the specimens were tested and compared. It showed that the rupture strength of the specimens of the FCPBC structure is markedly larger than that of the specimens of the fiber-discontinuous pillar-board composite (FDPBC) structure. At last, the experimental result was analyzed for illumining the mechanism of the FCPBC structure in the enhancement of the strength. [ABSTRACT FROM AUTHOR]

It is essential to explore the molecular therapeutic effect of warm and tonic herb treatment for individuals with typical kidney-yang deficiency. In this report, we have identified members of a family with a history of suffering from cold and kidney-yang deficiency syndromes. First, we have employed the accumulated scores of the 40-items clinical scoring indicators for kidney-yang deficiency and cold syndromes to clinically assess the presence or absence of the deficiency for 15 family members. We then proceeded to compare the gene expression profiles of RNA isolated from blood samples, prior to and post-herbal treatment, of a sibling (brother and younger sister) that are suffering from the deficiency using cDNA microarrays with 18816 genes. Following treatments with the warming and tonic herb, the accumulated clinical scores obtained from the 40-items clinical scoring indicators were compared to those obtained pre-treatment. It was observed that the accumulated clinical scores were reduced by 1/3 for the brother and 2/3 for his younger sister following the treatments. Furthermore, we have demonstrated that the level of gene expression for a total of 33 genes at pre-treatment was modulated after treatments with the warming and tonic herb and correlated well with the clinical improvements of their syndromes. These results suggest that the combination of gene profiling and the accumulated clinical scores obtained from the 40-items clinical scoring indicators may provide an accurate clinical assessment and a way to monitor the therapeutic efficacy of the warming and tonic herb treatment. [ABSTRACT FROM AUTHOR]