Determination Of Correction Factors Research Articles

Accurate Technique for the Calibration of High-Voltage Capacitance and Dissipation Factor Bridges up to 1 kHz

This paper presents a comprehensive methodology for the precise calibration of high-voltage capacitance and dissipation factor (DF) bridges. The technique involves meticulous adjustments using a digital high-precision phase and ratio-measuring system to determine correction factors for DF and capacitance measurements. Unlike other methods that are limited to a narrow range, this approach allows calibration across the entire operational working spectrum of any bridge. While the method has been developed up to 1 kHz, its adaptability for future requirements is facilitated by the developed software. This method has been carried out by calibrating a highly accurate bridge for a capacitor ratio of up to 100, with DFs ranging from −0.01 to 0.01 and currents ranging from 0.1 mA to 1 A. Linear correction factors are established, with their accuracies being rigorously quantified. This methodology achieves expanded uncertainties as low as 3.5 µF/F (3.5 ppm) for capacitance and 2.2 × 10−⁶ for DFs, significantly enhancing measurement reliability across diverse high-voltage capacitor applications.

Collection efficiencies of cylindrical and plane parallel ionization chambers: analytical and numerical results and implications for experimentally determined correction factors

Objectives. To derive a collection efficiency formula, fGauss , for cylindrical ionization chambers in pulsed radiation beams from a volume recombination model of Boag et al (1996 Phys. Med. Biol. 41 885–97) including free electrons. To validate fGauss and a parallel plate chamber formula fexp using an ion transport code and calculate changes in collection efficiencies caused by electric field charge screening at 0.1–100 mGy doses-per-pulse. And to determine collection efficiencies CE∞ predicted at infinite voltage in the absence of avalanche effects by fitting scaled formulae to efficiencies computed for 100–400 V chamber voltages and 10 and 100 mGy doses-per-pulse. Approach. Calculations were performed for an idealized parallel plate chamber with 2 mm electrode separation d , and for an idealized cylindrical chamber with 0.5 and 2.333 mm inner and electrode radii rin and rout . Main results. fGauss and fexp predict the same collection efficiencies for cylindrical and parallel plate chambers satisfying d2=(rout2−rin2)ln(rout/rin)/2 , an equivalence condition met by the chambers studied. Without charge screening, efficiencies computed using the code equalled fGauss and fexp . With screening, efficiencies changed by ⩽0.03%, ⩽1.1% and ⩽21.3% at 1, 10 and 100 mGy doses-per-pulse, and differed between the chambers by ⩽0.9% and ⩽19.6% at ⩽10 and 100 mGy dose-per-pulse. For fits of fexp and fGauss , CE∞ values were ⩽1.2% and ⩽17.6% from unity at 10 and 100 mGy per pulse respectively, closer than for other formulae tested. Significance. Allowing for screening, fGauss and fexp described computed collection efficiencies to within 0.03%, 1.1% and 21.3% at doses-per-pulse ⩽1, 10 and 100 mGy. Equivalence of the two chambers broke down at 100 mGy per pulse. Departures of CE∞ values from unity suggest that collection efficiencies determined experimentally by fitting fGauss or fexp to readings made at multiple voltages will be accurate to within 1.2% and 17.6% at 10 and 100 mGy per pulse respectively.

Method for determination of the spectral mismatch correction factors for the luminous responsivity of photometers when measuring the characteristics of LED lamps

This paper describes the challenges associated with the metrology of LED sources. The main problem is the difference between the spectra of LED lamps and the spectrums of reference lamps, which are mainly highly stable and well-reproducible incandescent lamps. The difference in spectra leads to the fact that the luminous responsivity of the calibrated photometer will be different for the reference incandescent lamp and for the LED lamp. The difference is caused by the fact that a relative spectral characteristic of the photometer responsivity is always different from the spectral responsivity of the human eye (V(λ) curve), which determines all luminous quantities. The greater the difference between the relative spectral responsivity of the photometer and V(λ) is, the more the luminous responsivity of the photometer will differ for the reference lamp and for the LED lamp. The paper describes a method developed at the NSC “Institute of Metrology” for experimental determination of mismatch correction factors of luminous responsivity that account for the difference in the LED spectra to solve the problems of metrological support of LED sources. Methods of experimental study of mismatch correction factors for measuring instruments of luminous quantities of LED radiation sources are presented.

Determination of correction factors and correction coefficients for calculations of the absorbed dose

The need to control the dose received by a patient during radiation therapy (RT) is dictated by the quality assurance requirements, which encompass a broad system of organizational and technical measures aimed at achieving consistency and precision in dosimetry measurements. The ultimate goal of using a quality assurance system in RT is to ensure high accuracy in delivering the dose to the tumour, reducing the irradiation volumes of normal, healthy tissues and organs near the target (tumour lesion). It has been established that to enhance the effectiveness of radiation treatment and to reduce the number of complications in subsequent periods, it is necessary to irradiate the local target in the patient’s body with a dose error no greater than ±5%. To control the calculation of the absorbed dose in water using thermoluminescent (TL) dosimeters, irradiated on a gamma therapeutic device for remote radiation therapy, it is necessary to study the influence of various factors (fading, non-linearity of indications, energy dependence, reproduction of the TL signal, presence of a holder) on the magnitude of the TL signal. We have studied and identified various corrective factors and their error values that may affect the calibration of the system (TLD-100 powder (Rexon), thermoluminescent reader PCL-3). In determining the corrective factors to account for the daily drift of the PCL-3 device, the TL signal obtained during the exposure was adjusted based on the control powder indicators. As a control powder, TLD-100 (Rexon) was used, irradiated with an absorbed dose of 2 Gy under standard conditions and aged four months to obtain a stable TL signal.

Development of correction coefficients for cable cross-sections selection in polymeric cable channel

Relevance. The need to develop correction coefficients for selecting cable sections when laying in the polymeric cable channel in the Russian Federation. Currently, there are no recommendations fixed by the state standards for laying cable power lines in polymer pipes. Aim. To develop correction factors for laying cable power lines in the polymer cable channel. Objects. Cable transmission lines laid underground in polymer pipes. Methods. Numerical simulation of combined frequency-stationary method; determination of correction factors based on interpolation of model results; evaluation and analysis of comparison of cables in corrugated and smooth polymer pipes. Results. Calculations of the long-term current load for cables laid in the polymeric cable channel showed the effectiveness of this method of laying cable lines. The use of pipes with smooth walls makes it much more efficient to remove heat from cables into the environment (compared to a corrugated pipe), which allows you to increase the capacity of the same cable by about 25%, depending on the number of pipes laid nearby. Based on the results of the simulation of the thermal mode of corrugated and smooth polymer pipes, it can be concluded that corrugated pipe significantly complicates heat removal from the cable system to the environment (soil). This is due to the presence of air gaps in the ribbed structure of the corrugated pipe. The gaps filled with air act as a heat-insulating layer, unlike a smooth pipe in which this gap is absent. The developed coefficients will take into account the influence of the location of cables on their allowable current already at the design stage, which will reduce the cost of power transmission losses due to the wrong cable cross-section and high temperature.

Determination of the P rp and radial dose correction factor in reference dosimetry

Objectives. In an addendum to AAPM TG-51 protocol, McEwen et al, (DOI: 10.1118/1.4866223) introduced a new factor P rp to account for the radial dose distribution of the photon beam over the detector volume mainly in flattening filter free (FFF) beams. P rp and its extension to non-FFF beam reference dosimetry is investigated to see its impact in a clinical situation. Approches. The P rp was measured using simplified version of Sudhyadhom et al (DOI: 10.1118/1.4941691) for Elekta and Varian FFF beams with two commonly used calibration detectors; PTW-30013 and Exradin-A12 ion chambers after acquiring high resolution profiles in detectors cardinal coordinates. For radial dose correction factor, the ion chambers were placed in a small water phantom and the central axis position was set to center of the sensitive volume on the treatment table and was studied by rotating the table by 15-degree interval from −90 to +90 degrees with respect to the initial (zero) position. Main results. The magnitude of P rp varies very little with machine, detector and beam energies to a value of 1.003 ± 0.0005 and 1.005 ± 0.0005 for 6FFF and 10FFF, respectively. The radial anisotropy for the Elekta machine with Exradin-A12 and PTW-30013 detector the magnitudes are in the range of (0.9995±0.0011 to 1.0015±0.0010) and (0.9998±0.0007 to 1.0015±0.0010), respectively. Similarly, for the Varian machine with Exradin-A12 and PTW-30013 ion chambers, the magnitudes are in the range of (1.0004±0.0010 to 1.0018±0.0018) and (1.0006±0.0009 to 1.0027±0.0007), respectively. Significance. The P rp is ≤ 0.3% and 0.5% for 6FFF and 10FFF, respectively. The radial dose correction factor in regular beams also does not impact the dosimetry where the maximum magnitude is ±0.2% which is within experimental uncertainty.

Establishing a nutrition calculation model for catering food according to the influencing factors of energy and nutrient content in food processing.

This study aimed to establish an accurate and efficient scientific calculation model for the nutritional composition of catering food to estimate energy and nutrient content of catering food. We constructed a scientific raw material classification database based on the Chinese food composition table by calculating the representative values of each food raw material type. Using China's common cooking methods, we cooked 150 dishes including grains, meat, poultry, fish, eggs, and vegetables and established a database showing the raw and cooked ratios of various food materials by calculating the ratio of raw to cooked and the China Total Diet Research database. The effects of various cooking methods on the nutritional composition of catering food were analyzed to determine correction factors for such methods on the nutritional components. Finally, we linked the raw material classification, raw and cooked ratio, and nutritional component correction factor databases to establish a model for calculating the nutritional components of catering food. The model was verified with nine representative Chinese dishes. We have completed the construction of an accurate and efficient scientific calculation model for the nutritional composition of catering food, which improves the accuracy of nutrition composition calculation. The model constructed in this study was scientific, accurate, and efficient, thereby promising in facilitating the accurate calculation and correct labeling of nutritional components in catering food.

СЛИЧЕНИЕ ДОЗИМЕТРИЧЕСКИХ СИСТЕМ ФОТОННОГО И НЕЙТРОННОГО ИЗЛУЧЕНИЙ, ИСПОЛЬЗУЕМЫХ В ОРГАНИЗАЦИЯХ ГОСКОРПОРАЦИИ «РОСАТОМ» ДЛЯ КОНТРОЛЯ В СИТУАЦИИ ПЛАНИРУЕМОГО ОБЛУЧЕНИЯ

Purpose: Using the example of reviewing and discussing the results of comparison tests of dosimetric systems of gamma and neutron radiation used in organizations of the State Corporation “Rosatom”, to assess the current state of reliability of monitoring the planned exposure of workers in fields of mixed gamma-neutron radiation using the considered dosimetric systems in order to produce recommendations for corrective actions to ensure a unified approach to conduct individual dosimetric control of external exposure. Results: All measuring instruments for individual dose equivalent of photon and neutron radiation, presented in comparison tests, comply with up-to-date requirements for individual dosimetric control systems. All measuring instruments confirmed their measuring capabilities, showed satisfactory quality of measurement results and the absence of a systematic bias in the measurement results. Analysis of the results of measuring the individual dose equivalent of neutron radiation showed that problems affecting the quality of the results obtained were identified in the considered instruments of measuring personal dose equivalent. The following factors might be the sources of problems: lack of knowledge about the real characteristics of radiation fields (spectral characteristics, radiation direction, etc.) at workplaces; insufficient research of the method used for measuring neutron radiation under real conditions (technical and metrological characteristics and features of the individual dosimeters used); failure to take into account the weighing coefficients for neutrons of various energies when measuring instruments are calibrated and when real measurements are conducted. Conclusion: It is necessary to organize and conduct investigations of the metrological characteristics of the measuring instrument that are used under conditions typical for a specific radiation object. After finishing these experimental studies, it is recommended to test the methodology with an analysis of the compliance of the accuracy indicators with the requirements of the relevant guidelines. In order to solve the problem of a lack of knowledge about the real characteristics of radiation fields, radiation safety services of organizations are recommended to organize and conduct research aimed at studying such characteristics using radiometric and spectrometric methods, experimental modeling of the process of personnel exposure using anthropomorphic phantoms and determining correction factors for the individual dosimeters used.

Determination of road surface correction factors for CNOSSOS-EU in Ireland

Transport Infrastructure Ireland (TII) is a state agency in the Republic of Ireland. The primary function of TII is to provide an integrated approach to the future development and operation of the national roads network and light rail infrastructure throughout Ireland. TII are designated as the Noise Mapping Body (NMB) responsible for the development of strategic noise maps for all national roads carrying in excess of 3 million vehicles a year. Directive 2002/49/EC (commonly referred to as the Environment Noise Directive, 'the END') relates to the assessment and management of environmental noise. It is the main instrument of the European Union (EU) to quantify noise pollution levels, and trigger action within both Member States and at EU level. The END has the aim of establishing a common approach to the management of noise within the EU. Commission Directive (EU) 2015/996 established the common noise assessment methodology for Europe (CNOSSOS-EU). The CNOSSOS-EU road traffic noise emission model calculates rolling noise for different vehicle categories as a function of speed and frequency. The emission is initially calculated under reference conditions, then corrected for differing situations. For road surfaces which do not align with the reference surface, road surface correction factors should ideally be developed, otherwise a number of default values are provided within CNOSSOS-EU which are taken from the Dutch national noise assessment method, Rmg2012, and therefore contain only surfaces that are common in the Netherlands. For the implementation of CNOSSOS-EU in Ireland, a project was undertaken to develop road surface corrections for at least the three most common pavement types on the TII network with no direct match to the CNOSSOS-EU database. This paper will describe the measurements taken on Irish roads, the resulting road surface corrections, and our conclusions and recommendations for using the road surface corrections.

Proton dosimetry in a magnetic field: Measurement and calculation of magnetic field correction factors for a plane-parallel ionization chamber.

The combination of magnetic resonance imaging and proton therapy offers the potential to improve cancer treatment. The magnetic field (MF)-dependent change in the dosage of ionization chambers in magnetic resonance imaging-integrated proton therapy (MRiPT) is considered by the correction factor , which needs to be determined experimentally or computed via Monte Carlo (MC)simulations. In this study, was both measured and simulated with high accuracy for a plane-parallel ionization chamber at different clinical relevant proton energies and MFstrengths. The dose-response of the Advanced Markus chamber (TM34045, PTW, Freiburg, Germany) irradiated with homogeneous 10 10 cm quasi mono-energetic fields, using 103.3, 128.4, 153.1, 223.1, and 252.7 MeV proton beams was measured in a water phantom placed in the MF of an electromagnet with MF strengths of 0.32, 0.5, and 1 T. The detector was positioned at a depth of 2 g/cm in water, with chamber electrodes parallel to the MF lines and perpendicular to the proton beam incidence direction. The measurements were compared with TOPAS MC simulations utilizing COMSOL-calculated 0.32, 0.5, and 1 T MF maps of the electromagnet. was calculated for the measurements for all energies and MF strengths based on the equation: , where and were the temperature and air-pressure corrected detector readings with and without the MF, respectively. MC-based correction factors were determined as , where and were the doses deposited in the air cavity of the ionization chamber model with and without the MF, respectively. Furthermore, MF effects on the chamber dosimetry are studied using MC simulations, examining the impact on the absorbed dose-to-water ( ) and the shift in depth of the Braggpeak. The detector showed a reduced dose-response for all measured energies and MF strengths, resulting in experimentally determined values larger than unity. For all energies and MF strengths examined, ranged between 1.0065 and 1.0205. The dependence on the energy and the MF strength was found to be non-linear with a maximum at 1 T and 252.7 MeV. The MC simulated values agreed with the experimentally determined correction factors within their standard deviations with a maximum difference of 0.6%. The MC calculated impact on was smaller 0.2 %. For the first time, measurements and simulations were compared for proton dosimetry within MFs using an Advanced Markus chamber. Good agreement of was found between experimentally determined and MC calculated values. The performed benchmarking of the MC code allows for calculating for various ionization chamber models, MF strengths and proton energies to generate the data needed for a proton dosimetry protocol within MFs and is, therefore, a step towardsMRiPT.

La dosimetrie du 177Lu-PSMA

New metabolic internal radiotherapy treatments, such as 177Lu-PSMA, as well as compliance with regulatory requirements will ultimately lead to the systematic implementation of personalized dosimetry to estimate the absorbed dose to the organs at risk and to the tumors targeted by the treatment. However, several steps are essential before getting started. In this article, we propose to detail them based on our personal experience and data from the literature, highlighting the difficulties relating to their realization. The first of these steps, often minimized, concerns the implementation of all the elements (settings, determination of correction and conversion factors) required to obtain images suitable for quantification on a conventional SPECT-CT camera. We will then detail the difficulties involved in delineating the volumes of the organs and tumors studied, obtaining their pharmacokinetic curves, to finally finish with the determination of the absorbed dose and discuss its limits.

Kilovoltage X-ray beam quality effect on the relative response of alanine pellet dosemeters.

Determination of beam quality correction factors is crucial for performing accurate alanine pellet dosimetry in non-reference fields. For some complex irradiation geometries, interpolation from literature data is more convenient than an experimental approach to establish these factors. Here we investigate the validity of extracting quality correction factors from literature data based on information on beam qualifiers such as half-value layer (HVL) or effective energy ${E}_{\text{eff}}$. A combination of Monte Carlo calculated dose ratios and a microdosimetric assessment of the relative efficiency allows for numerical evaluation of quality correction factors for a wide array of X-ray qualities. The computational analysis demonstrates that the average energy of the X-ray beam is optimal for characterizing the relative response. Special care should be taken when using the common X-ray beam qualifiers HVL or ${E}_{\text{eff}}$ to determine quality correction factors from literature data.

Laboratory determination of gravimetric correction factors for real-time area measurements of electronic cigarette aerosols: Part 2

The popularity and widespread of electronic cigarettes (ECIGs) have warranted a necessity for monitoring different populations directly or indirectly exposed to particulate matter (PM) from ECIGs. To accurately estimate exposure to aerosols from ECIGs, it is important to correctly measure the concentration of aerosols. Real-time aerosol monitors are usually based on optics that provides biased measurements that are adjusted using filter correction factors. In addition, low-cost aerosol sensors have become popular that allow widespread of these sensors and can estimate ECIG aerosol exposure after calibration. Therefore, this study determined the filter correction factors for three aerosol monitors (MiniWRAS, pDR, SidePak) based on exposure to six ECIG brands and two particle sizes (PM1 and PM2.5). In addition, the GeoAir2 low-cost monitor was evaluated compared to filter corrected MiniWRAS measurements for these exposures. The study also evaluated the real-time measurements and Mass Median Diameter (MMD) for each ECIG brand. The correction factors varied between aerosol monitors, ECIG brands and particle sizes, with ranges for PM2.5 that span between 1.85 and 2.42 (MiniWRAS), 0.50 and 0.58 (pDR) and 0.24 and 0.28 (SidePak). The GeoAir2 underestimated the reference measurements but had a high correlation (r = 0.90 - 0.94), showing that the monitor can be effectively calibrated to provide good estimates. The real-time average PM2.5 measurements differed between aerosol instruments with concentrations that ranged between 1,398 and 3,706 µg/m3 (MiniWRAS), 5,479 and 16,825 µg/m3 (pDR), and 9,783 and 29,808 µg/m3 (SidePak). Finally, the MMD values spanned between 0.45 and 0.80 µm based on the MiniWRAS measurements. The differences between the raw real-time measurements for the aerosol monitors show the necessity for developing filter correction factors to accurately measure ECIG exposure.

Determination of Self-absorption Correction Factors of Some Algae Samples: An Experimental study

The purpose of this study to examine experimentally self-absorption correction factors (SACFs) of some algae samples using gamma-ray spectrometry. Various algae samples were collected from Boğaçay in Antalya, Turkey. Collected algae samples were dried, and masses of the samples were calculated. Then densities of the samples were calculated. Each of algaes was counted with and without point sources which are 22Na, 60Co, 133Ba, and 137Cs about 1000 seconds using high purity germanium detector. The SACFs of algae samples were calculated between 80 keV and 1332 keV gamma-ray energies. As a result, SACFs of studied algae samples generally reduce as gamma-ray energy enhances. SACFs of some algae samples are nearly steady because of the densities and elemental contents of the studied algaes.

Experimental and Monte Carlo-based determination of magnetic field correction factors in high-energy photon fields for two ionization chambers.

The integration of magnetic resonance tomography into clinical linear accelerators provides high-contrast, real-time imaging during treatment and facilitates online-adaptive workflows in radiation therapy treatments. The associated magnetic field also bends the trajectories of charged particles via the Lorentz force, which may alter the dose distribution in a patient or a phantom and affects the dose response of dosimetry detectors. To perform an experimental and Monte Carlo-based determination of correction factors , which correct the response of ion chambers in the presence of external magnetic fields in high-energy photonfields. The response variation of two different types of ion chambers (Sun Nuclear SNC125c and SNC600c) in strong external magnetic fields was investigated experimentally and by Monte Carlo simulations. The experimental data were acquired at the German National Metrology Institute, PTB, using a clinical linear accelerator with a nominal photon energy of 6 MV and an external electromagnet capable of generating magnetic flux densities of up to 1.5 T in opposite directions. The Monte Carlo simulation geometries corresponded to the experimental setup and additionally to the reference conditions of IAEA TRS-398. For the latter, the Monte Carlo simulations were performed with two different photon spectra: the 6 MV spectrum of the linear accelerator used for the experimental data acquisition and a 7MV spectrum of a commercial MRI-linear accelerator. In each simulation geometry, three different orientations of the external magnetic field, the beam direction and the chamber orientation were investigated. Good agreement was achieved between Monte Carlo simulations and measurements with the SNC125c and SNC600c ionization chambers, with a mean deviation of 0.3% and 0.6%, respectively. The magnitude of the correction factor strongly depends on the chamber volume and on the orientation of the chamber axis relative to the external magnetic field and the beam directions. It is greater for the SNC600c chamber with a volume of 0.6cm3 than for the SNC125c chamber with a volume of 0.1 cm3 . When the magnetic field direction and the chamber axis coincide, and they are perpendicular to the beam direction, the ion chambers exhibit a calculated overresponse of less than 0.7(6)% (SNC600c) and 0.3(4)% (SNC125c) at 1.5 T and less than 0.3(0)% (SNC600c) and 0.1(3)% (SNC125c) for 0.35 T for nominal beam energies of 6 MV and 7MV. This chamber orientation should be preferred, as may increase significantly in other chamber orientations. Due to the special geometry of the guard ring, no dead-volume effects have been observed in any orientation studied. The results show an intra-type variation of 0.17% and 0.07% standard uncertainty (k=1) for the SNC125c and SNC600c, respectively. Magnetic field correction factors for two different ion chambers and for typical clinical photon beam qualities were presented and compared with the few data existing in the literature. The correction factors may be applied in clinical reference dosimetry for existing MRI-linearaccelerators.

Using applied program packages in determining optimum cutting modes

Purpose. Comparison of the functionality of application program packages when determining optimal cutting modes during mechanical processing. Creation of a mathematical model with technological limitations when boring a shaft in one pass and carrying out calculations. The methods. Research methods were based on the principles of optimization of cutting processes, the theory of cutting and cutting tools, standard methods of determining correction factors were used when creating technological limitations. The smallest machine processing time is chosen as the objective function. Using the functionality of the mathematical package Mathcad and the "Turning optimization" program. Findings. The created mathematical model of turning optimization sufficiently fully describes the machining process. The difference between calculations by two methods is no more than 10%. The functionality of the application programs is enough to determine the optimal parameters of the cutting modes - the number of revolutions of the machine spindle and feed. In addition, when using the Mathcad package, it is possible to add or remove technological constraints. Without a suitable database of correction factors, the search and calculation process is complicated. On the other hand, the "Turning optimization" program works in automatic mode, you only need to enter the initial data. But it is impossible to change the technological limitations, the insufficient number of standard materials of cutting tools and parts. The originality. A mathematical model of optimization of cutting modes when boring a shaft to a pass with corresponding technological limitations was created and investigated. A comparison of application program packages was carried out when determining the optimal cutting modes. Advantages and disadvantages of application programs are defined. Practical implementation. The proposed mathematical model of optimization of cutting modes during turning allows to determine the optimal parameters of the number of revolutions and feed of the machine. Its use will greatly facilitate calculations carried out by designer-technologists when designing technological routes for processing parts and calculating cutting modes. This will significantly reduce production preparation time, especially when using CNC machines.

Fatigue testing on bitumen binder using different column specimen shapes

The use of cylindrical column specimens to characterise the fatigue degradation of bituminous materials is useful to unify existing fatigue testing methods at different length scales (i.e., asphalt binder, mastic and mortar). However, these specimens commonly fail at the interface between the test material and the steel holders. To overcome this difficulty, this study investigates the fatigue characterisation of four binders using four different notched column geometries. The benefit of these geometries is that they induce failure at the center of the specimen. Finite element simulations were used to determine correction factors to account for the influence of the specimens' shape. Curves of the fatigue life as a function of the applied effective strain were successfully obtained for the different binders. The results show that the use of these notched geometries ensures true cohesive failure within the specimen and is an effective method to characterise fatigue damage in asphalt binders.

Determination of correction factor of flow velocity on eroded rills by electrolyte tracer method with double injectors

Flow velocity is an important hydrodynamic parameter to study the rill erosion process, especially the erosion dynamic process. The dye tracer method is a common and simple method to measure the rill flow velocity. However, a correction factor is required to convert the surface flow velocity to the mean flow velocity. The reliable correction factor is vital to determine the mean flow velocity. A total of 144 flow velocities (surface and mean) were measured using electrolyte and dye tracers at the corresponding distances (4, 6, 12, and 16 m) under different inflow rates (6, 9, 12, 15, 18, and 21 L min−1) on eroded rills. Results showed that the electrolyte tracer method with double injectors can accurately measure the mean flow velocity under the condition of a long slope in the field. The Reynolds numbers varied between 1433 and 15864. And the correction factor α varied between 0.220 and 0.874 with an average value of 0.557. The correction factor was positively correlated with the rill width, depth, cross-sectional area, flow depth, and Reynolds number. Furthermore, the correlation coefficients between correction factor and hydraulic parameters were greater than those between correction factor and rill morphological parameters. Moreover, the correction factor could be predicted by the equation of inflow rate, Reynolds number, and slope length. The results verified the application of an improved double injector electrolyte tracer method on a long slope in the field, clarified the influence of rill morphology and hydraulic parameters on the correction factor, and developed a reference for mean flow velocity determined using the dye tracer method.

Experimental determination of the Ag L -subshell x-ray-production cross sections by electron impact through two bulk target methods

The experimental determination of x-ray-production cross sections by electron impact on thick samples is faced in this work, especially focusing on the $L$ subshells of Ag. The integrodifferential method used by An et al. is compared with a recently implemented approach involving the ionization distribution function. The first method has shown good results under suitable conditions, namely, when multiple scattering, bremsstrahlung enhancement, and other secondary effects are negligible. Monte Carlo simulations were performed in order to analyze the influence of these conditions and therefore to extend the validity range of the method by adding a correction factor. The second approach uses the ionization distribution function $\ensuremath{\phi}(\ensuremath{\rho}z)$ to predict the intensity of the emitted photons; this magnitude is assessed by the poema software, previously developed, and it is used to determine correction factors to the cross sections included in the software database. Both approaches were tested by fitting several $L$-shell spectra measured in a wide interval of incident electron energies, ranging from 4.0 to 25 keV, with an electron microprobe equipped with a wavelength-dispersive spectrometer. The x-ray-production cross sections obtained for each $L$ subshell and the total $L$ x-ray-production cross section were compared with theoretical predictions based on the distorted-wave approach theory and with experimental determinations when available.

Dosimetric accuracy of the Convolution algorithm for Leksell Gamma Plan radiosurgery treatment planning: Evaluation in the presence of clinically relevant inhomogeneities.

The Leksell Gamma Plan Convolution algorithm (LGP-Convolution) has not been widely adopted. This mainly stems from the higher calculated beam-on times relative to the standard ray tracing-based LGP-TMR10 dose calculation algorithm. This study aims to evaluate the accuracy of the LGP-Convolution in scenarios where the treated lesions are in the vicinity of or encompassed by bone and/or air inhomogeneities. The solid water dosimetry phantom provided by the vendor was modified to include bone and air inhomogeneities. Two treatment planning scenarios were investigated involving a single shot and multiple shots, respectively. Treatment planning and dose prescription were performed using the LGP-Convolution algorithm. Triple channel film dosimetry was performed using GafChromic EBT3 films calibrated in terms of absorbed dose to water in a 60 Co beam. Monte Carlo (MC) simulation dosimetry was also performed in the inhomogeneous experimental geometry using the EGSnrc MC platform and a previously validated sector-based phase-space source model. MC simulations were also employed to determine correction factors required for converting EBT3 measurements at points within the bone and air inhomogeneities from dose-to-water values to the corresponding dose to medium values. EBT3 dose to medium correction factors ranged with field size (4, 8, or 16mm) within 0.941-0.946 for bone and 0.745-0.749 for air inhomogeneities. An excellent agreement was found between the LGP-Convolution calculations with corresponding EBT3 and MC dose to medium results at all measurement points, except those located inside the air inhomogeneity. The latter is of no clinical importance and excluding them yielded gamma index passing rates of nearly 100% for 3% local dose difference and 1mm distance-to-agreement criteria. The excellent agreement observed between LGP-Convolution calculations and film as well as MC results of dose to medium indicates that the latter is the quantity reported by the LGP-Convolution.