RBCCPS / Evaporation is one of the inherent processes of the earth’s ecosystem. Water bodies, earth’s surface and vegetation all contribute significantly towards the total evaporation which eventually leads to the formation of clouds. The factors which affect the total evaporation (evaporation & transpiration) are the surface temperature, ambient temperature, relative humidity, external wind speed, pressure, surface area and geometry. This thesis deals with the contributors of total evaporation individually viz. open water bodies; soil-like surfaces; and leaf-like surfaces. A ceramic infrared heater has been used to mimic the heating due to sun’s radiation in all the experiments which were conducted in the quiescent atmosphere. This thesis has been broadly categorized into two parts: - (a) evaporation from bare water surface; and (b) evaporation from a porous media. In part (a), we present experimental results on the evaporation from a bare water surface heated either from above using the infrared radiations or from below using immersed heaters. Heating from below leads to unstable stratification and convection while infrared heating from above leads to stable stratification. The effect of water-side convection on the evaporation from a bare water surface has been investigated and all the experimental results have been combined to obtain a power law relation between Sherwood number (Sh) and Rayleigh number (Ra). Part (b) of the thesis has been further split into three major categories: - (1) evaporation from spheres based conventional porous media; (2) evaporation from unconventional porous media containing rods, capillaries, and plates; and (3) evaporation from leaf-like surfaces. In all the experiments, a precision weighing balance was used to measure the evaporation rate. A thermal camera was used to get the surface temperature fields, and fluorescein dye mixed with water gave insightful results on the evaporation process. In particular the red deposits of fluorescein particles revealed the evaporation sites. In most of the experiments, the infrared heating was of the order of 1000W/m2. Different sized glass and acrylic containers were used in this thesis. Mono-disperse glass beads (closest to mimic the natural soils), stainless steel balls, sieved natural sand and hydrophobic Ball Grid Array balls have been used to create the spheres-based conventional porous media. Evaporation was found to undergo three stages which depended on the spheres size and the heat flux supplied. In the 1st stage of evaporation capillary film(s) pulls water from beneath the porous media to the top surface and the evaporation rate remained high, close to that obtained from a water surface. Capillary break-up occurs in the transition regime which is followed by the 2nd stage of evaporation where a new vaporization plane is formed within the porous media. In the 2nd stage, heat is conducted through the top dried layer to the water below where evaporation takes place and the evaporation rate drops drastically. Transition to 2nd stage happened earlier for coarser spheres at constant heat flux. Along with the wetting properties, the spheres size has been found to effect capillary break-up length (a measure of capillary film strength) and hence the duration of the stages of evaporation drastically. Surface images captured using the thermal camera clearly showed the presence of water till the capillary break-up. The capillary break-up length was also found to be affected significantly by the heat flux. Apart from the experimental findings of mono-disperse spheres, two layers of different sized glass spheres have also been investigated. The presence of complicated network of textural layering in the earth’s surface is a well-known fact. Preferential evaporation was clearly seen in the experiments with texturally layered porous media independent of the orientation viz. vertical or horizontal layering. The stacking positions are found to be critical in determining the overall evaporation characteristics. The geometry of a pore between three spheres in mutual contact is very complicated. Simpler pore geometry would be between two rods/plates in contact or three rods in mutual contact or stacks of either of these two. We call these types of the porous media as “Unconventional porous media” as they possess many unique features not shown by a conventional porous media. The evaporation characteristics of vertically stacked rods was found to be dominated by the corner films present in the near-zero radii contacts. Unlike the conventional porous media, the capillary break-up length was found not to depend on the rod diameter. The capillary break-up length for vertically stacked rods was larger than for the spheres case and was also found to be independent of the heat flux, for the range investigated in this thesis. A mathematical model has been developed for understanding the evaporation from the vertically stacked rods. Experiments with horizontally stacked pencil leads showed early capillary break-up while with horizontally stacked glass rods, capillary break-up was not observed. Experimental investigations of porous media containing vertically stacked plates have also been studied. Water trapped between two consecutive plates are treated as 2D source of evaporation. Plants regulate their O2-CO2 content via tiny holes present on the leaves called “Stomata”. The average size of a stoma is nearly 20μm and the total area covered by stomata is close to 5% of the leaf area. However the higher transpiration rates (60-70 % compared to a bare water source) sustained by a plant has remained a mystery for the phytologists. In view of this we mimic the leaf-type using regularly spaced holes on the silicon wafers from which water evaporates. The leaf-mimics had different hole-diameter but open area ratio was kept constant. In all the cases the evaporation ratio (ratio of the evaporation rate from the leaf mimic to that of the evaporation rate of a bare water surface at the same surface temperature) was found to increase at lower heat fluxes. With increasing the hole-size evaporation rate was found to decrease. The leaf-mimic with the smallest hole-size had the highest evaporation rate and the evaporation ratio increased from 0.46 at 800W/m2 to 0.64 at 400W/m2. The 3D nature of diffusion near these tiny holes enhances the evaporative flux which explains the high evaporation rates even for low open area ratios.

The objective of this thesis is to reach theoretical understanding of the unusual relationship between charge-ordering and superconductivity in correlated-electron systems. The competition between these broken symmetries and magnetism in the cuprate high temperature superconductors has been extensively discussed, but exists also in many other correlated-electron superconductors, including quasi-two-dimensional organic charge-transfer solids. It has been suggested that the same attractive interaction is responsible for both charge-order and superconductivity. We propose that the specific interaction is the tendency in correlated-electron systems to form spin-singlet bonds, which is strongly enhanced at the commensurate carrier density p of ½ a charge carrier per site, characteristic of all superconducting charge-transfer solids. To probe superconductivity driven by electron correlations, a necessary condition is that electron-electron interactions enhance superconducting pair-pair correlations, relative to the non-interacting limit. We have performed state of the art numerical calculations on the two-dimensional Hubbard model on different triangular lattices, as well as other lattices corresponding to K-BEDT-TTF based organic charge transfer solids, for the complete range of carrier densities per site p (0 ≤ p ≤ 1). We have shown that pair-pair correlation for each cluster is enhanced by electron-electron interaction only for p ≃ 0.5, far away from the density range thought to be important for superconductivity. Although initial focus is on charge-transfer solids, the results of the research will impact the field of correlated electrons as a whole. We believe our calculations will provide fundamental and fresh insight to the theory of superconductivity in strongly correlated systems.

Workers involved in hydraulic fracking processes are exposed to various types of chemicals and dusts in their workplaces, such as proppants, which hold open the fissures created in the fracking process. Recently, ceramic proppants have been developed that may be less hazardous to workers than traditional proppants. Pulmonary function testing of workers producing ceramic proppant was used to assess the potential inhalation hazards of ceramic proppant. Male workers (n = 100) from a producer of ceramic proppant were evaluated with pulmonary function test data collected and evaluated using The American Thoracic Society (ATS) acceptability criteria. A comparison group was selected from the Third National Health and Nutrition Examination Survey (NHANES III) spirometry laboratory subset. No pulmonary function deficits were found in the worker group in comparison to the NHANES III population. Multiple linear regression analysis showed that the mean FEV1 and FVC values in workers were 0.11 and 0.08 liters respectively, and were greater as compared to the NHANES III population. Curiously, an FEV1/FVC ratio of less than 0.8, when compared to the NHANES III group, produced an odds ratio of 0.44 in worker group, indicating less risk of preclinical pulmonary dysfunction. Overall, exposure to ceramic proppant was not found to produce an adverse impact on pulmonary function in workers engaged in the manufacture of ceramic proppant.

Recent crisis and economic recession caused in many countries problems with drop in inflation and overall downturn in economic growth. The Central Banks found themselves in so called zero lower bound. This thesis describes the situation of deflation, zero lower bound and liquidity trap. These conditions called for the use of alternative monetary policy tools. The main goal of the thesis is to evaluate the use of foreign exchange rate intervention as unconventional tool in a small open economy with inflation targeting regime represented by the Czech Republic in the analytic part. Thesis examines other non-standard instruments and provides reasons for the Czech National Bank decision. The analysis shows the complexity of the issue and provides the evidence that exchange rate commitment was not displayed to the desired price level. The tool could lead to expected repercussion, but the effect is impacted by factors, which Central Bank cannot control. The effect of the CB way to fight the decreasing inflation will be better shown after the CB exit from the commitment.

The diploma thesis focuses on quantitative easing in Japanese economy. In the first part the problematic is set into a theoretical frame and then is connected with the development of the modern Japanese economy. The thesis describes the progress of the both waves of quantitative easing which have been implemented so far as well as the circumstances of their start and their so far known impacts. The application part presents an evaluation of the impacts of the current wave of quantitative easing. The evaluation is based on the impulse-response analysis.

The aim of this research is to explore the integration of ad hoc and mobile sensors into a conventional Electrical Resistance Tomography (ERT) system. This is motivated by the desire to improve the spatial resolution of 3D reconstructed images that are produced using ERT. The feasibility of two approaches, referred to as the Extended Electrical Tomography (EET) and Augmented Electrical Tomography (AET) are considered. The approaches are characterized according to the functionality of the sensors on the ad hoc 'pills'. This thesis utilizes spectral and numerical analysis techniques, with the goal of providing a better understanding of reconstruction limitations, including quality of measurements, sensitivity levels and spatial resolution. These techniques are applied such that an objective evaluation can be made, without having to depend heavily on visual inspection of a selection of reconstructed images when evaluating the performance of different set-ups. In EET, the sensors on the pills are used as part of the ERT electrode system. Localized voltage differences are measured on a pair of electrodes that are located on an ad hoc pill. This extends the number of measurements per data set and provides information that was previously unobtainable using conventional electrode arrangements. A standalone voltage measurement system is used to acquire measurements that are taken using the internal electrodes. The system mimics the situation that is envisaged for a wireless pill, specifically that it has a floating ground and is battery-powered. For the present exploratory purposes, the electronic hardware is located remotely and the measured signal is transmitted to the PC through a cable. The instrumentation and data acquisition circuits are separated through opto-isolators which essentially isolates both systems. Using a single pill located in the centre of a vessel furnished with 16 electrodes arranged in a single plane, spectral analysis indicates that 15 of the 16 extended measurements acquired using the adjacent current injection strategy are unique. Improvement is observed for both the sensitivity and spatial resolution for the voxels in the vicinity of the ad hoc pill when comparing the EET approach with the conventional ERT approach. This shows the benefit of the EET approach. However, visual inspection of reconstructed images reveals no apparent difference between images produced using a regular and extended dataset. Similar studies are conducted for cases considering the opposite strategy, different position and orientation of the pill, and the effect of using multiple pills. In AET, the sensors on the ad hoc pills are used as conductivity probes. Localized conductivity measurements provide conductivity values of the voxels in a discretized mesh of the vessel, which reduces the number of unknowns to be solved during reconstruction. The measurements are incorporated into the inverse solver as prior information. The Gauss-Newton algorithm is chosen for implementation of this approach because of its non-linear nature. Little improvement is seen with the inclusion of one localized conductivity measurement. The effect on the neighbouring voxels is insignificant and there is a lack of control over how the augmented measurement influences the solution of its neighbouring voxels. This is the first time that measurements using ad hoc and 'wireless' sensors within the region of interest have been incorporated into an electrical tomography system.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第22112号 / 理博第4539号 / 新制||理||1652(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 前野 悦輝, 教授 松田 祐司, 教授 石田 憲二 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 新制・課程博士 / 博士(理学) / 甲第22989号 / 理博第4666号 / 新制||理||1669(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 石田 憲二, 教授 柳瀬 陽一, 教授 前野 悦輝 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

In the early 21st century, oil and gas production in the U.S. was conjectured to be in terminal-irreversible decline. But, thanks to the advancement of hydraulic fracturing technologies over the last decade, operators are now able to produce two-thirds of U.S. oil and gas output from almost impermeable shale formations. Despite the enormous success of the ‘shale revolution’, there are still debates about how long shale production will last and if there will be enough to subsidize a meaningful transition to ‘greener’ power sources. Most official pronouncements of shale oil and gas reserves are based on purely empirical curve-fitting approaches or geological volumetric calculations that tend to largely overestimate the actual reserves. As an alternative to these industry-standard forecasting methods, we propose a more reliable, ‘transparent’, physics-guided and data-driven approach to estimating future production rates of oil and gas in shales. Our physics-based scaling method captures all essential physics of hydrocarbon production and hydrofracture geometry, yet it is as simple as the industry-favored Decline Curve Analysis (DCA), so that most engineers can adopt it. We also demonstrate that our method is as accurate as other analytical methods and has the same predictive power as commercial reservoir simulators but with less data required and significantly faster computational time. To capture the uncertainties of play-wide production, we combine physical scaling with the Generalized Extreme Value (GEV) statistics. So far, we have implemented this method to nearly half a million wells from all major U.S. shale plays. Since the results of our analyses are not subject to bias, policy-makers ought not to assume that the shale production boom will last for centuries.

The thesis deals with the technology of laser cutting. The beginning is concerned with a general description of laser technology and laser division into basic groups. Next part refers to possible industrial use of laser beam, especially for cutting. Other chapters deal with the components suitable for the manufacture of this technology, technical preparation of production and the proposal to increase manufacturing flexibility when changing products. The last part is devoted to technical and economic evaluation.