1,275 research outputs found
Effect of deformation route on the mechanical properties of CP-Ti deformed by Equal Channel Angular Pressing (ECAP)
No full textThe effect of deformation route on the mechanical properties of grade-1 CP-Ti deformed by equal-channel angular pressing (ECAP) was studied using tensile testing, TEM observation, X-ray pole figure measurement, and ODF calculation. Route Be showed high yield stress and comparatively large uniform elongation, thus high ultimate tensile strength, because of its fine grain structure with high angle grain boundary. The reason for this was because of the occurrence of prismatic slip in route Be, in addition to the commonly occurring basal slip. Route C showed surprisingly high yield stress despite of its unfavorable grain structure because of the significant contribution of texture hardening
Naucnaja diglossija v istoriceskom obrazovanii Aleksandra II (Lekcii o Petre Velikom)
No full textThe article focuse on the historical education of the Tsar Alexander II with a particular attention to the field of Russian History and the role of Peter the Great. The author analyzes the different scientific languages and approaches used by his teachers in teachin Russian history and their interaction
Testing and analysis of axial gap permanent magnet DC motors
No full textThis thesis is concerned primarily with the testing and analysis of design variations of the Lynch motor, which is an axial gap permanent magnet dc machine. These variants include: a standard production motor, a motor with low iron volume, a motor with bigger area of magnets and a motor using powder iron instead of laminations. The powder iron motor was constructed by the author, while all the other motors were provided by the Lynch Motor Company.Tests were conducted to evaluate motor circuit parameters, losses and efficiency using a purpose built test rig which was built in the first stage of the project. Finite element analysis (FEA) was used to determine the levels of the magnetic saturation in the different motors and calculate torque, inductance and EMF. The FEA was also used as bases for comparison with analytical electromagnetic calculations. A dynamic circuit model, whose parametric were derived from FEA and analytical calculations validated by test, was also constructed to study the effect of brush thickness on circulating current and torque production.The results of the work revealed that the larger magnet motor has a high level of saturation resulting in a higher slope of the torque-speed curve. The lower iron volume motor and the powder iron cored motor produced less torque and have less flux density than the standard Lynch motor. The test results proved that the selected powder iron material is usable in the Lynch rotated armature but it still needs improvements to close the performance gap with laminations. The powder iron motor has back emf that is 10% lower than the standard motor, and consequently a lower efficiency.The results show that performance of the Lynch motor can be improved by optimising the size of the saturated parts of the motor, which are the stator discs and the armature teeth. In addition, careful selection of brush number, geometry and type can improve the motor performance.An alternative single gap motor was also studied. The test results show that it has more armature reaction than the dual gap motor and therefore it produced less torque with less efficiency
Silent Conversations in Rudyard Kipling’s Kim and Ruskin Bond’s Rusty novels
No full textThe essay undertakes an analysis of the connections and conversations between Rudyard Kipling’s Kim (1901) and Ruskin Bond’s largely autobiographical Rusty (1955-) novels. Kipling’s Kim has evoked many literary responses and reactions across India. While writers such as Sarath Kumar Ghosh, Rabindranath Tagore, T.N. Murari, and even Sashi Tharoor have boldly written back to Kim, Ruskin Bond silently acknowledges it in his Rusty series of children’s fiction. At times, Bond’s pointed and conscious avoidance of Kipling becomes his means of accepting Kipling’s influence on him. The essay traces the implicit dialogue between these two Anglo-Indian authors and their protagonists. It undertakes a close reading of their novels to analyse the evolution of English literature and Anglo-Indianism in India, while also examining the divided identities of the authors and their fictional protagonists
DS_10.1177_0022034520901719 – Supplemental material for Dentoalveolar Defects in the Hyp Mouse Model of X-linked Hypophosphatemia
No full textSupplemental material, DS_10.1177_0022034520901719 for Dentoalveolar Defects in the Hyp Mouse Model of X-linked Hypophosphatemia by H. Zhang, M.B. Chavez, T.N. Kolli, M.H. Tan, H. Fong, E.Y. Chu, Y. Li, X. Ren, K. Watanabe, D.G. Kim and B.L. Foster in Journal of Dental Research</p
Electrochemical behavior of calcium titanate coated Ti-6Al-4V substrate in artificial saliva
No full textIn this study, calcium titanate (CaTiO3) gel was prepared by mixing calcium nitrate and titanium isopropoxide in 2-methoxy-ethanol. CaTiO3 gel was single-layer coated on Ti-6A1-4V using a sol-gel dip-coating technique. The coating was calcined at 750??C in air by utilizing a very slow heating rate of 2??C/min. The crystalline phases of the coating were characterized by x-ray diffraction using a slow scan rate of 1??/min. The morphology of the coating was analyzed by scanning electron microscopy. The corrosion behavior of Ti-6Al-4V samples coated with CaTiO3 films were tested in an artificial saliva solution by potentiodynamic polarization and were quantified by the Tafel extrapolation method. The electrochemical parameters showed a considerable increase in the corrosion resistance for the CaTiO3-coated Ti-6Al-4V samples compared to bare substrates
Rocking Revisited 1. Rocking of a Single Cube on a Breakwater Slope
No full textPrototype single layer armour units on a breakwater slope are observed to break. To predict when breakage occurs, the objective of this research project is to obtain knowledge on, and measurements of the rocking behaviour and failure mode of single layer armour units. A single cube on a breakwater slope is subjected to investigations.
Wave flume tests are conducted, in which rotations of a single cube are measured as a consequence of various hydraulic conditions. The tested parameters are: degree of exposure of cube, wave height, wave steepness and position on slope in relation to the water level. A three-axis accelerometer, which is placed in the cube’s centre, is applied during this Master's Thesis. Furthermore, wave gauges are applied to measure the wave conditions.
For future CFD-modelling, measurements are conducted on water pressures during wave run-up on a non-rotating cube, using a pressure sensor. In addition, wave run-up velocities and the movements of the cube are captured with two cameras
Sustainable conjunctive use of groundwater for additional irrigation
No full textCurrently millions of private wells in the Punjab are pumping groundwater as an additional source for irrigation to compensate for irregular surface water supply. Since the 1990s, most of them are skimming wells that aim to reduce the salinity of the pumped groundwater. However, salinization continues to rise over time, often above acceptable limit, which threatens food production. This thesis aims to develop a solution to make groundwater use for additional irrigation sustainable, i.e., to limit the salinity of pumped water in the long run. Based on a model analysis, it was shown that skimming technologies cannot prevent salinization, irrespective of parameters of subsurface, for which some unique pumping tests were analyzed and geophysical measurements were carried out in the Punjab. Sustainability is sought in balancing both water and salt on the scale of field or farm. Both analytical and numerical models were used to show that the adopted concepts will work.Water ManagementCivil Engineering and Geoscience
Groundwater System Identification through Time Series Analysis
No full textGroundwater, water in the ground. Although it is invisible, it is a vital resource for all terrestrial life (whether direct or indirect). Many processes interact with it. Rain recharges it, as it infiltrates the soil. Plant roots take it up, and their leaves evaporate it. It discharges to rivers and streams, and is abstracted with pumping wells. It is controlled with ditches and drainage means. Such processes and activities leave their traces in the groundwater level fluctuations. Careful analysis of these fluctuations may reveal much of the functioning of systems, and of the effects of individual factors. This is shown by many, but practiced by too few, as traditional time series analysis theory and software are complex. In this thesis, a new method of time series analysis is presented. Its continuous time formulation fits existing physical-hydrologic theory and methods well. It is shown that groundwater level responses generally take the shape of simple distribution functions. This notion, combined with the program Menyanthes that was developed, enable the quick and easy analysis of large numbers of time series. The spatial patterns that emerge in the results of multiple models literally add another dimension to the technique. As time series models are usually accurate also, they may be valuable to every (eco)hydrologist.Water ManagementCivil Engineering and Geoscience
Determination of optimal separation well distance for single borehole ATES systems, in the Netherlands, implementing an an axi-symmetric numerical model
No full textAquifer thermal energy storage (ATES) is a growing technology in the Netherlands. There are two kinds of ATES configurations the doublet and the single borehole ATES (SB-ATES) layout. The limited subsurface space in combination with the lower construction cost and the lower performance of the SB-ATES lead to the need to optimize their design. This master thesis focuses on gaining a better insight in the processes that occur around this configuration. Specifically, how anisotropy influences the efficiency of the design and what the optimal distance between filter screens is, in order to limit the interference between the screens, as it has a negative impact on system performance. To meet these two objectives, an axisymmetric numerical model was developed in a MATLAB environment, using MODFLOW and MT3DMS or SEAWAT groundwater flow and transport simulators. The simulation of heat advection was conducted applying the finite different method (FD method), it was the only method compatible with axial symmetric models that produced consistent results. As the FD method is subjected to numerical dispersion, three different grid resolutions were tested that were the 0.25, 0.50 and 1.00 m, respectively. The finest grid was decided to be used in the elaboration, as it gave the most accurate results compared to larger thickness width grid cells. Capacity test and borehole profile data were used to calibrate the overall vertical anisotropy of the case-studies. The capacity test allowed the calibration of one hydraulic parameter, for which the overall vertical anisotropy was chosen. The Kozeny-Carmen equation was used to calculate the hydraulic conductivity of each soil layer. This overall vertical anisotropy even though was estimated roughly, can be used to determine the presence of overlooked clay layers during the drilling of the borehole (anisotropy >10). A sensitivity analysis was applied to estimate the optimum distance between the filter screens. Three different types of SB-ATES, called GT15xx, GT20xx and GT25xx, were examined separately. The numbers indicate the installed pump capacity in m3/h while their mean and representative screen lengths are 5, 7 and 10m respectively. For the sensitivity analysis, three discharge fractions, Qfrac, were tested with values 0,25, 0.50 and 1.00 and three anisotropy values of 2, 5 and 10, these values are representative for sandy soils. The simulation time was 5 years, which was sufficient to the recommended efficiencies. The results showed that the maximum efficiency is practical independent of system type. The optimum separation distance for an anisotropy of 2 is respectively, 25, 30 and 35 m for Qfrac 0.25, 0.50 and 1.00. The evaluation of the sensitivity analysis was conducted, using real-scale case-studies and taking into account the distribution of conductivities along the layers. The available 18 case-studies were examined in terms of efficiency; it was found that a thin resistance layer between the screens, like a clay or peat layer, influences positively the performance of SB-ATES systems. On the other hands, when there is a high conductive zone between the screens, the efficiency drops. Finally, it was found that temperature induced differences in density and viscosity have a negligible effect on SB-ATES systems, at least with injection temperature differences between warm and cold wells up to 120C.HydrogeologyWater ManagementCivil Engineering and Geoscience
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