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Strength and Mechanism of Adhesion to the Substrate Layer while Applying Plasma Coatings in Oxidizing Environments
Get PDFIt has been examined that when an oxide layer is treated under atmospheric conditions on a treated substrate surface, in the contact zone, an oxide layer is always present. This mixed oxide layer influences the contact temperature and the adhesion strength of the particles that are being coated to the substrate surface.Henceforth the process of heating of the contact layer of surface oxides was investigated. The experimentation was demonstrated by coupling of the particles of the coating layer with the surface layer when wetting is provided by melting of the oxide layer. The conditions of the wettable contact under nonstationary heat exchange were determined depending on the thermophysical properties of the contact pair, the temperatures of the coating particles and the substrate. The wetting time was evaluated depending on the thickness of the oxide layer. The identity of the adhesion strength of the coating and the cohesive strength of the oxide layer was substantiated.
It was evaluated that for the inner surface of the coating elastic modulus and breaking stress is about 20% higher than for the external. The detected difference is related to the presence of the temperature gradient across the thickness for coating
Bio-Polymer Based Tragacanth Gum (TG) Loaded Fe3O4 Nanocomposite for the Sequestration of Tenacious Congo Red Dye from Waste Water
Get PDFWater polluted by hazardousdyes such as congo red (CR) face challenges to the regulation of water supplies. In the laboratory scale experiment, we report the novel approach for the synthesis of Fe3O4/TG nanocomposite. The Fe3O4/TG nanocomposite was synthesized by co-precipitation method. The surface properties and chemical compositions have been investigated using Fourier transform infrared spectroscopy (FTIR), X- ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) instrumentation. The XRD study indicates that nanocomposite were formed in the nano-scale (11.5 nm) and this is in accordance with TEM results. The maximum removal of CR dye was recorded at 2.0 pH. Approximately, 89.51 % deterioration of congo red (CR) dye has been achieved within 250 min of solar exposure. The prepared Fe3O4/TG nanocomposite is found to efficient photocatalyst for the removal of noxious dye from waste water
Differential Gain Comparison of Optical Planar Amplifier on Silica Glasses Doped with Bi-Ge and Er, Yb Ions
Get PDFThe paper presents the measurement and calculation of the optical amplifier gain and the optimal length of the active optical amplifier waveguide doped with Bi-Ge radiation complexes compared to an optical amplifier with active doping with ions Er3+, Yb3+. At present are using optical amplifiers for the high-capacity optical communication systems in the narrow spectral region of 1530–1560 nm, determined by the gain bandwidth of erbium-doped fiber amplifiers (EDFA) or erbium-doped optical planar amplifiers (EDPA) realized as active planar waveguides in the optical integrated circuits technique. However, it is possible increase wavelength region up to 1610 nm, where optical losses of telecommunication fibers are less than 0.3 dB per km, if appropriate amplifiers are available. In this regard, the development of novel optical amplifiers operating in this spectral region have of great importance. The paper summarizes the results measurement of the attenuation and emission spectra for net gain spectra calculation of the new ion exchange Ag+ – Na+ optical Er3+ and Yb3+ doped active planar waveguides realized on silica glass substrates and parameters of novel optical amplifiers for extension of the bandwidth from 1530 to 1610 nm doped by bismuth – erbium ions
Design of Electronic Moxibustion Instrument for Umbilical Therapy and Preliminary Analysis of Temperature Field
Get PDFMoxibustion has a history of thousands of years. Umbilical moxibustion achieves prevention and treatment of diseases through moxibustion at the golden section of the human body-the umbilicus. It has enough clinical practice experience. Traditional treatment methods have problems such as irritating smoke, uncontrollable temperature, experience-based, and difficult to quantify. Based on the principle of traditional umbilical moxibustion, a structural design of an electronic smokeless umbilical moxibustion instrument is proposed, which belongs to indirect moxibustion and has the advantages of smokeless, electric heating, portability, temperature monitoring and controllability. The internal heat transfer process of the moxibustion instrument is mainly heat convection and heat radiation. Based on ANSYS software, the internal temperature field of the moxibustion instrument is analyzed, and the steady-state temperature distribution and the temperature change characteristic curve of different positions with time are obtained to verify the rationality of the structural design. At the same time, lay a research foundation for the measurable and quantifiable effects of moxibustion on umbilical therapy
Assessment of Backscattered Radiation Dose at Exposed Object’s Level during X-Ray Examinations
Get PDFThis paper estimates backscattered radiation doses at patient’s positioning level (exposed object) using different X-ray tubes. The effects of different exposure sittings (X-ray tube voltage, exposure intensity, exposed area, dosimeter position, and distance between X-ray tube and imaged object surface) on backscattered radiation doses are estimated using different dosimeters and x-ray units. The quantity of recorded backscattered radiation dose -which reflects from patient’s table or bucky to image receptor and exposed patient - is determined by the position of dosimeter between exposed object’s table or bucky and X-ray tube according to backscatter angle, at higher backscattered angle, the dosimeter records more backscattered dose. The results showed that, increase in kVp, exposure intensity, and exposed area led to a concomitant increase in the quantity of backscattered radiation, whereas the Increase in distanc e between X-ray tube (source) and imaged object surface reduces the amount of backscattered radiation dose. As well as, there is no remarkable difference in recorded backscattered dose due to the position of X-ray tube or the direction of incident X-ray photons
Stabilizing a Class of Switched Nonholonomic Mechanical Systems
Get PDFStructurally reconfigurable or variant robot systems can provide better mobility and environmental adaptability. In this paper it is shown that a class of nonholonomic constraints robot systems can be changed to a class of special linear time varying (LTV) systems, and by applying switching control strategy the control singular problems of nonholonomic systems caused by the local coordinates can be overcome, and provides a flexible approach of optimal motion planning for mobile robotic systems. For variant robot systems with switched discontinuous dynamics, it is shown that the switching control approaches can be used to stabilize a class of switched heterogeneous nonholonomic systems. Some numerical simulation results also demonstrate the effectiveness of the control strategy proposed in this paper
µ-Planner: A Robot Path Planning Approach Based on Language Measure of Unsupervised Automata
Get PDFThis paper proposes a robot path planner based on language measure, m-planner. Workspace is discretized in a occupancy grid map and we model the system by considering how events, associated to robot’s motions, take it to different cells (discrete positions). The calculated language measure values corresponds to a gradient, which the robot can use reach its destination by choosing events that take it to states with higher measure values. Concepts of Lapace’s equation and harmonic functions are used to prove that our method guarantees both the existence and monotonicity of language measure. The proposed method is simple and computationally inexpensive and guarantees existence of path from any co-accessible state to the destination. Experiments considering different scenarios have been performed to validate and compare m-planner with similar methods
The Effect of Fuel Emulsion on Fuel Saving in Fire Tube Boilers of Tartous Company for Cement and Construction Materials
Get PDFIn this work, the combustion of heavy oil and its emulsions with water, in the fire-tube boilers, was investigated in experiments on an industrial scale. The performance of the fire-tube boilers, used in Tartous company for cement and construction materials, was studied when they were employed to be operated with heavy fuel oil (HFO) and with the water phase of emulsified heavy oil containing 8 vol. % water and 92 vol. % heavy fuel oil (HFO). The emulsified water/heavy fuel oil (W/HFO) with 8 vol. % of water content showed no separation and contained the smallest and most homogeneous water-in-HFO (W/HFO) droplets after stability tests. Four boilers, each with 8 ton h-1 steam capacity, have been operated for 4 months with a regular heavy fuel oil HFO and W/HFO. It has been found that the micro-explosion, observed in W/HFO, improved the boiler efficiency and reduced the fuel consumption by 12.99%
Improving Electricity Production in Solar Chimney Power Plants with Sloping Ground Design: An Extensive CFD Research
Get PDFUnlike other solar energy systems, solar chimney power plants (SCPPs) allow power output even when there is no sun. SCPPs are promising with their simple structure and 24-hour electricity production potential. Massive pressure tower in the system maintains continuous energy generation irrespective of climatic conditions. Solar energy harnessed by the huge collector area is transmitted to the gorund material for sensible or latent heat storage purpose, and this stored energy during daytime yields to enhanced thermal and buoyant effects even after sunset. SCPPs are also in the centre of interest owing to their eco-friendly operation not causing any CO2 emission. Design aspects in SCPPs are widely studied numerically by researchers. However, geometric design factors are merely analysed for collector and chimney, and very few attempts are done for the ground design. In the present work, a new design for ground is proposed in order to improve the energy stored in the ground material, and the upward movement of the air flow in the system from collector to chimney by changing the ground geometry. The upward movement of the air under the collector is enhanced with the new design created by inclining the ground at a distance of 21 m from the chimney inlet to a certain distance from the collector inlet. ANSYS WORKBENCH based CFD analysis is carried out based on the geometric dimensions of the Manzanares pilot plant. Analyses are based on a 90° 3D CFD model for the purpose of time saving in iterations. The CFD model is supported by RNG k-? turbulence and DO (discrete ordinates) solar ray tracing models. After CFD results are verified with the experimental data, simulations are repeated for different designs and the ideal design is achieved. It is observed that the maximum air flow velocity, which is 14.202 m/s on the horizontal ground for the reference case, is improved by 34.1% in the new design to 19.046 m/s. In addition, it is seen that the power output of the reference case (54.333 kW) is enhanced by 23.04% to 66.855 kW
Performance of Normal Geometrical Hydrodynamic Inclined Fixed Pad Thrust Slider Bearing with the Interfacial Slippage Occurring on the Stationary Surface in the Inlet Zone and on the Whole Moving Surface
Get PDFAn anaysis is presented for investigating the performance of the hydrodynamic inclined fixed pad thrust slider bearing with a normal geometry where the interfacial slippage occurs on the stationary surface in the inlet zone and on the whole moving surface, based on the limiting interfacial shear strength model. The calculation results show that compared with the classical mode of the bearing (without any interfacial slippage), this bearing has a significantly higher load-carrying capacity but a much lower friction coefficient in the same operating condition. The study shows the considerable improvement of the bearing performance by the introduced interfacial slippage