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Item type:Publication, Indirect Measure Voltage and Exposure Time Device for Medical X-ray(2019-01-10); X-ray machine is used to create an image of diagnosing or treatment by using X-ray beam. X-ray beams are harmful to the body's cells when the radiation dose is high enough. Therefore, the X-ray machine must always be calibrated or test to ensure that the X-ray machine is accurate to keep users safe. In this research presents the design and construction of x-ray testing device. It will focus on measuring the two main parameters of the x-ray machine. Measurement of exposure time (x-ray emission time) and measurements of peak kilovoltage from the x-ray tube. This device has 2 parts, hardware and software. The hardware is the circuit consist of intensifying screen for a radiation receiver and converted energy from x-ray into light energy. The wavelength of the light emitted is in the range of 500-600 nm, then use a circuit of photodiode. It is a semiconductor device that converts light into an electric current. The electric current is a full-wave rectification waveform corresponding to the 100 Hz high voltage supply of the x-ray tube. Take the signal from the electric current to filter circuit for reducing noise. And then take the signal to the microcontroller (Arduino). Arduino is used for taking the signal to process in Visual Studio program to measure exposure time and peak kilovoltage of x-ray, which can be measured and processed immediately. The waveform is digitized, and peak detected with Arduino. The number of peaks is then converted to exposure time, i.e. one peak corresponds to 10 milliseconds. The result, exposure time and peak kilovoltage of x-ray, will show on window form application in Visual Studio program. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Upscaling heterogeneity in aquifer reactivity via exposure-time concept: Forward model(2006-03-20); Ginn, Timothy R.Reactive properties of aquifer solid phase materials play an important role in solute fate and transport in the natural subsurface on time scales ranging from years in contaminant remediation to millennia in dynamics of aqueous geochemistry. Quantitative tools for dealing with the impact of natural heterogeneity in solid phase reactivity on solute fate and transport are limited. Here we describe the use of a structural variable to keep track of solute flux exposure to reactive surfaces. With this approach, we develop a non-reactive tracer model that is useful for determining the signature of multi-scale reactive solid heterogeneity in terms of solute flux distributions at the field scale, given realizations of three-dimensional reactive site density fields. First, a governing Eulerian equation for the non-reactive tracer model is determined by an upscaling technique in which it is found that the exposure time of solution to reactive surface areas evolves via both a macroscopic velocity and a macroscopic dispersion in the artificial dimension of exposure time. Second, we focus on the Lagrangian approach in the context of a streamtube ensemble and demonstrate the use of the distribution of solute flux over the exposure time dimension in modeling two-dimensional transport of a solute undergoing simplified linear reversible reactions, in hypothetical conditions following prior laboratory experiments. The distribution of solute flux over exposure time in a given case is a signature of the impact of heterogeneous aquifer reactivity coupled with a particular physical heterogeneity, boundary conditions, and hydraulic gradient. Rigorous application of this approach in a simulation sense is limited here to linear kinetically controlled reactions. © 2006 Elsevier B.V. All rights reserved. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Upscaling heterogeneity in aquifer reactivity via the exposure-time concept: Inverse model(2006-03-20); Ginn, Timothy R.A novel inverse technique is proposed to quantitatively characterize macroscopic variability in aquifer reactivity in a Lagrangian representation. Reactivity heterogeneity is expressed in terms of distributions of flux over cumulative time of exposure of the solution to reactive surface area, termed here 'cumulative reactivity'. In cases involving single aqueous species the combined effects of physical and reactivity heterogeneity on reactive solute transport can often be established and further investigated through joint distributions of flux over travel time and cumulative reactivity. The inverse technique requires the breakthrough curve of a passive tracer to determine the distribution of flux over travel time, and additional breakthrough curves of reactive tracers provide additional moments of the distribution of flux over cumulative reactivity given travel time. Thus breakthroughs of one passive and two reactive tracers can provide the mean and variance of the distribution of flux over cumulative reactivity. This Lagrangian characterization is achieved with knowledge of the types of reactive surfaces present, but not their spatial locations. The distributions can subsequently be applied via forward modeling using the same technique to predict breakthrough curves of other solutes undergoing first-order reactions in similar physically and chemically heterogeneous configurations. © 2006 Elsevier B.V. All rights reserved.