Academic literature on the topic 'Experimental analyses of qr-code scanning'

One of the utmost challenges of hot aluminum extrusion is to design the die cavities, used to extrude thin-walled profiles, by considering the effective nitriding surface treatment of the die bearing surface in terms of nitride layer uniformity. In the present study, various AISI H13 steel samples (having commonly-used profile geometric features) are manufactured using wire EDM and subsequently nitrided using two-stage controlled nitriding treatment. The uniformity and depth of nitride layers formation on these are investigated in terms of compound layer and total nitride case depth using optical and scanning electron microscopes. Finite element code ABAQUS is used to simulate the nitrding process using sequentially coupled thermo-diffusive analysis in line with experimental set up. Both experimental and numerical results are found in close agreement in terms of nitrogen concentration and corresponding micro-hardness profiles. Some design modifications are implemented in FE code for critical die profile features for uniform nitride layer development. In view of the current results, some design guidelines are suggested for effective and uniform nitride layer formation in order to secure high quality extruded product and extended die life.

Successful cryopreservation protocols have been developed for a limited number of cell types through an extensive amount of experimentation. To optimize current protocols and to develop effective protocols for a larger range of cells and tissues it is imperative that accurate transport models be developed for the cooling process. Such models are dependent on the thermodynamic properties of intracellular and extracellular solutions, including heat capacity, latent heat, and the physical phase change temperatures. Scanning techniques, such as differential-scanning calorimetry (DSC) and differential thermal analysis are effective tools for measuring those thermodynamic properties. It is essential to understand the behavior of the in house fabricated differential-scanning calorimeter given different cooling and warming rates to reassure and validate the obtained experimental results. A 1-D transient CFD code was created in Matlab using Patankar’s theory to not only validate obtained experimental results but aid in optimizing the control system to produce linear cooling and warming rates. A freezing model was also implemented as a subroutine to numerically observe the effect of heat release and absorption of the sample during a run. The numeric model is composed of a multilayer scheme that incorporates a thermoelectric module which provides the primary temperature control along with the micron sized bridge with sample holder and thermocouple. An electric current profile is imported in from either an experimental run to validate results or from an optimization program to determine the optimum electrical current profile for a desired temperature profile. Numeric detection of heat capacity, latent heat, and thermal resistance has also been demonstrated.

Abstract The velocity distributions inside a centrifugal separator with outside and inside diameters of 152.4 mm (6″) and 76.2 mm (3″), respectively, have been investigated experimentally and numerically to obtain optimum separation efficiency. Two 12.7 mm (1/2-inch) holes were drilled on the external surface of the separator to measure the velocity distribution in the separator. Two direction velocities (tangential direction along the cylinder surface and axial along the vertical direction) were measured to compare with the numerical simulation results. A 6060P Pitot probe was employed to obtain the velocity distribution. The dust samples (a mixture of steel particle and dust) from the dust collection box were analyzed using a Phillips XL30 Scanning Electron Microscope. FLUENT code is used as the numerical solver for this fully three-dimensional problem. The fluid flow in the separator is assumed to be steady and incompressible turbulent flow. The standard k–ε model was employed in this study. Non-uniform, unstructured grids are chosen to discretize the entire computation domain. Almost 100,000 cells are used to discretize the whole separator. The constant velocity profile is imposed on the inlet plane. The pressure boundary condition is adopted at outlet plane. Comparing the velocity distribution and separation efficiency from the experiment and the numerical modeling shows that the experimental results and the estimated data agree fairly well and with a deviation within ±10%.

Thermophysical properties including density, specific heat, and thermal diffusivity of a poly (diallyl phthalate) inert filler composite material were characterized over a wide temperature range from room temperature to 800 °C. Over this temperature range, the material decomposition was approximated by a one-step process with first-order kinetics. Thermal kinetics data were obtained by thermal gravimetric analysis with Fourier transform infrared spectroscopy (TGA-FTIR) and thermophysical properties were obtained from differential scanning calorimetry (DSC) and laser flash diffusivity experiments. The response of the material to radiant heating was simulated with a computational heat transfer, multidimensional, finite element code. Additionally, the experimental uncertainty in the measurements was quantified to estimate the uncertainty in the reaction parameters due to heating rate and variability in inert filler-polymer composition in large sample sizes. Hence, the thermal response and the uncertainty were quantified for a complex decomposing material in a practical geometry for technologically important applications.

Abstract Magnetic Resonance Thermometry (MRT) is a developing diagnostic technique that leverages advanced medical technologies to accurately measure the temperature of a fluid flow within and around complex geometries. The full three-dimensional temperature field obtained by MRT can be used to analyze heat transfer characteristics and potentially investigate thermal boundary layers near arbitrarily complex surfaces. This technique requires neither optical nor physical accessibility, thereby enabling a wide range of engineering applications. This paper describes the current state of the art for MRT measurement, detailing turbulent water channel tests, materials selection, scanning parameters, data analysis of time-averaged temperature measurements, and uncertainty estimates. The purpose of this work was to evaluate and refine the MRT technique to increase the accuracy of temperature measurements and minimize the error in fully turbulent flow measurements. In the present study, a plate with a vertical cylinder extending from both of its sides was placed between two channels, and a diagonal hole was drilled through the cylinder from one side of the plate to the other. This enabled fluid from one channel to mix with the fluid in the other. This experiment studied the mixing of two fluids at different temperatures. The upstream temperatures of each fluid were measured with thermocouples. Both flows were fully turbulent, and the colder temperature channel had a Reynolds number of 11,800. Tests were run with four different fluid temperatures for calibration and to determine any temperature dependence of measurements. Three-dimensional temperature field measurements are reported and details about data processing and procedures to conduct the experiments are provided. This work resulted in several notable improvements to MRT experimental methods. The test section and water channel were designed to limit the effects of thermal expansion in the stereolithography materials used for manufacturing the complex internal flow geometry. Multiple echo scans were used to minimize the effects of magnetic field drift commonly observed in extended scanning periods in MRI systems. Data analysis techniques were used to quantify expansion effects for both hot and cold flow cases. To quantify measurement uncertainty, the standard deviation of the mean was calculated at each data point across different scan numbers and confidence intervals established using a student t-test. An improved data processing code was used to filter data resulting in increased measurement accuracy and reduced uncertainty to less than 1 °C for most of the domain. Future work will further refine the experimental techniques to improve scanning procedures, employ high conductivity ceramics and larger geometries with relevant applications, and simplify data processing methods to generate full-field flow temperature data.

This paper addresses the issue of aerodynamic consequences of small variations in airfoil profile. A numerical comparison of flow field and cascade pressure losses for two representative repaired profiles and a reference new vane were made. Coordinates for the three airfoil profiles were obtained from the nozzle guide vanes of refurbished turboshaft engines using 3D optical scanning and digital modeling. The repaired profiles showed differences in geometry in comparison with the new vane, particularly near the leading and trailing edges. A numerical simulation was conducted using a commercial CFD code which uses the finite element approach for solving the governing equations. The computational predictions of the aerodynamic performance were validated with experimental results obtained from a transonic cascade consisting of blades with the same airfoil profiles. A CFD analysis was performed for the cascade at subsonic inlet and transonic exit conditions. Boundary layer growth, wake formation, and shock boundary layer interactions were observed in the two-dimensional computations. The flow field showed the presence of shock waves downstream of the passage throat and near the trailing edges of the blades. A conspicuous change in flow pattern due to subtle variation in airfoil profile was observed. The calculated flow field was compared with the flow pattern visualized in the experimental test rig using the Schlieren method. The total pressure calculation for the cascade exit showed an increase in pressure loss for one of the off-design profiles. The pressure loss calculations were also compared with the multi-hole total pressure probe measurement in the transonic cascade rig.

Selective laser melting is one of the powder bed fusion processes which fabricates a part through layer-wised method. Due to the ability to build a customized and complex part, selective laser melting process has been broadly studied in academic and applied in industry. However, rapidly changed thermal cycles and extremely high-temperature gradients among the melt pool induce a periodically changed thermal stress in solidified layers and finally result in a distorted part. Therefore, the temperature distribution in the melt pool and the size and shape of the melt pool directly determine the mechanical and geometrical property of final part. As experimental trial-and-error method takes a huge amount of cost, different numerical methods have been adopted to estimate the transient temperature and thermal stress distribution in the melt pool and powder bed. The most existing research utilizes the moving Gaussian point heat source to model the profile of the melt pool, which consumes a significant amount of computational cost and cannot be used to implement the part-level simulation. This research proposes a new line heat source to replace the moving point heat source. Some efforts are applied to reduce the computational cost. Specifically, a relatively large step size is used for the line heat source to reduce the number of time steps. In addition, a mesh refinement scheme is adopted to reduce the number of cells in each time step by refining the mesh close to the heat source and coarsening the mesh far away from it. On the other hand, efforts are implemented to increase the accuracy of the simulation result. Temperature-dependent material properties are considered in this FE framework. In addition, material transition among powder, liquid, and solid are incorporated in the developed FE framework. In this study, temperature simulation of one scanning track based on self-developed FE code is applied for Stainless Steel 316L. The simulation results show that the temperature distribution and history of melt pool within line heat source are comparable to that of the moving Gaussian point heat source. While the simulation time is reduced by more than two times depending on the length of line heat input. Therefore, this FE model can be used to numerically investigate the process parameters and help to control the quality of the final part.

This paper represents an analytical model for predicting mineral particle redistribution of coal blending during pulverized coal (PC) combustion in a pulverized coal-fired boiler. The objective of this research is to develop a computer program to perform the mass balance of total minerals after transformation during combustion. A MATLAB code was developed for coal blending mineral redistribution from single coal mineral redistribution in modular approach based on relative Hardgrove Grindability Index (HGI) of coals. The calculations of the single coal number of ash particles before and after combustion both for excluded and included minerals from the single coal proximate analysis, Malvern analysis, Computer Controlled Scanning Electron Microscopy (CCSEM) analysis, density and composition analysis were designed in a submodule. Utilizing single coal sub-module, the calculations of coal blending number of ash particles before and after combustion both for excluded and included minerals were designed in a module of MATLAB code. The blending modeling was designed to blend up to five sub-bituminous coals. Calculations were made for typical boiler combustion conditions ranging from 1,500K to 2,500K as flame temperature. The organically-associated ash content or mineral grains of each coal smaller than 1 micrometer was not included in the calculation of redistribution modeling. Coal particle fragmentation of blended coal was considered as same as single coal and size dependent phenomena. Partial coalescence model was assumed as more likely to occur. Blended coal was assumed to follow additive rule applied to mineral mass percentage based on sizes and mineral phase regardless grinding of coals separately or after blending if the HGI difference between highest and lowest HGI of coals arranged in ascending order stands within five. The modeling was demonstrated for KPU: AVRA and AVRA: Solntsevsky with specific blending ratio 80:20 and 20:80 respectively. The model for blended coal was validated by the mass balance of minerals before and after combustion. The resulting simplified particle size distribution of mass fraction of KPU: AVRA shows good agreement with experimental results of Kentucky #9 coal because of having a larger amount of included minerals of KPU coal. The model for blended coal mineral redistribution before and after combustion will be developed for the HGI difference between highest and lowest HGI of coals arranged in ascending order becomes greater than five and validated by minerals mass balance before and after combustion. This modeling will be used to predict number of mineral particles and its sizes that is a key parameter as to predict the problems like fouling and slagging and the related reduction of boiler efficiency. The results from this study will be further carried out to investigate ash deposition rates in post-boiler heat exchangers.