Effect of hemodialysis on intraocular lens power calculation.
Çalışkan, Sinan; Çelikay, Osman; Biçer, Tolga; Aylı, Mehmet Deniz; Gürdal, Canan
2016-01-01
To evaluate changes in ocular biometric parameters after hemodialysis (HD) in patients with end-stage renal disease (ESRD). Forty eyes of 40 patients undergoing HD were included in this cross-sectional study. Keratometry (K) readings, white-to-white (WTW) distance, central corneal thickness (CCT), anterior chamber depth (ACD), pupil diameter, lens thickness (LT), axial length (AL), and intraocular lens (IOL) power calculation were measured with Lenstar LS 900 (Haag Streit AG, Koeniz, Switzerland) before and after hemodialysis. Intraocular pressure (IOP) was measured with a non-contact tonometer (Tonopachy NT-530P, Nidek Co., LTD, Tokyo, Japan). Main outcomes were changes in biometric parameters after HD. Reliability of the measurements (intraclass correlation coefficients (ICCs)) and the effect size (Cohen's d) were also calculated. Mean difference in AL before and after HD was -0.041 ± 0.022 mm with ICCs > 0.90 (p 0.90 (p = 0.041 and Cohen's d = 0.20). Hemodialysis had no significant effect on K readings, WTW distance, CCT, ACD, LT, or IOP. Axial length and pupil diameter increase after HD with small effect size, while HD does not significantly affect IOL power calculations.
Calculation of crystalline lens power in chickens with a customized version of Bennett's equation.
Iribarren, Rafael; Rozema, Jos J; Schaeffel, Frank; Morgan, Ian G
2014-03-01
This paper customizes Bennett's equation for calculating lens power in chicken eyes from refraction, keratometry and biometry. Previously published data on refraction, corneal power, anterior chamber depth, lens thickness, lens radii of curvature, axial length and eye power in chickens aged 10-90 days were used to estimate Gullstrand's lens power and Bennett's lens power for chicken eyes, and to calculate the lens equivalent refractive index. Bennett's A and B constants for the front and back surface powers of the lens were calculated for data measured from day 10 to 90 at 10 day intervals, and mean customized constants were calculated. The mean customized constants for Bennett's equation for chicks were A=0.574±0.023 and B=0.379±0.021. As found previously, lens power decreases with age in chicks, while corneal power decreases and axial length increases. The lens equivalent refractive index decreases with age from 10 to 90 days after hatching. Bennett's equation can be used to calculate lens power in chicken eyes for studies on animal myopia, using standard biometry. Copyright © 2014 Elsevier B.V. All rights reserved.
Comparison of two optical biometers in intraocular lens power calculation
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Sheng Hui
2014-01-01
Full Text Available Aims: To compare the consistency and accuracy in ocular biometric measurements and intraocular lens (IOL power calculations using the new optical low-coherence reflectometry and partial coherence interferometry. Subjects and Methods: The clinical data of 122 eyes of 72 cataract patients were analyzed retrospectively. All patients were measured with a new optical low-coherence reflectometry system, using the LENSTAR LS 900 (Haag Streit AG/ALLEGRO BioGraph biometer (Wavelight., AG, and partial coherence interferometry (IOLMaster V.5.4 [Carl Zeiss., Meditec, AG] before phacoemulsification and IOL implantation. Repeated measurements, as recommended by the manufacturers, were performed by the same examiner with both devices. Using the parameters of axial length (AL, corneal refractive power (K1 and K2, and anterior chamber depth (ACD, power calculations for AcrySof SA60AT IOL were compared between the two devices using five formulas. The target was emmetropia. Statistical analysis was performed using Statistical Package for the Social Sciences software (SPSS 13.0 with t-test as well as linear regression. A P value < 0.05 was considered to be statistically significant. Results: The mean age of 72 cataract patients was 64.6 years ± 13.4 [standard deviation]. Of the biometry parameters, K1, K2 and [K1 + K2]/2 values were significantly different between the two devices (mean difference, K1: −0.05 ± 0.21 D; K2: −0.12 ± 0.20 D; [K1 + K2]/2: −0.08 ± 0.14 D. P <0.05. There was no statistically significant difference in AL and ACD between the two devices. The correlations of AL, K1, K2, and ACD between the two devices were high. The mean differences in IOL power calculations using the five formulas were not statistically significant between the two devices. Conclusions: New optical low-coherence reflectometry provides measurements that correlate well to those of partial coherence interferometry, thus it is a precise device that can be used for the
Improved accuracy of intraocular lens power calculation with the Zeiss IOLMaster.
Olsen, Thomas
2007-02-01
This study aimed to demonstrate how the level of accuracy in intraocular lens (IOL) power calculation can be improved with optical biometry using partial optical coherence interferometry (PCI) (Zeiss IOLMaster) and current anterior chamber depth (ACD) prediction algorithms. Intraocular lens power in 461 consecutive cataract operations was calculated using both PCI and ultrasound and the accuracy of the results of each technique were compared. To illustrate the importance of ACD prediction per se, predictions were calculated using both a recently published 5-variable method and the Haigis 2-variable method and the results compared. All calculations were optimized in retrospect to account for systematic errors, including IOL constants and other off-set errors. The average absolute IOL prediction error (observed minus expected refraction) was 0.65 dioptres with ultrasound and 0.43 D with PCI using the 5-variable ACD prediction method (p ultrasound, respectively (p power calculation can be significantly improved using calibrated axial length readings obtained with PCI and modern IOL power calculation formulas incorporating the latest generation ACD prediction algorithms.
Ramji, Hasnain; Moore, Johnny; Moore, C B Tara; Shah, Sunil
2016-04-01
To optimise intraocular lens (IOL) power calculation techniques for a segmental multifocal IOL, LENTIS™ MPlus(®) (Oculentis GmbH, Berlin, Germany) and assess outcomes. A retrospective consecutive non-randomised case series of patients receiving the MPlus(®) IOL following cataract surgery or clear lens extraction was performed at a privately owned ophthalmic hospital, Midland Eye, Solihull, UK. Analysis was undertaken of 116 eyes, with uncomplicated lens replacement surgery using the LENTIS™ MPlus(®) lenses. Pre-operative biometry data were stratified into short (<22.00 mm) and long axial lengths (ALs) (≥22.00 mm). IOL power predictions were calculated with SRK/T, Holladay I, Hoffer Q, Holladay II and Haigis formulae and compared to the final manifest refraction. These were compared with the OKULIX ray tracing method and the stratification technique suggested by the Royal College of Ophthalmologists (RCOphth). Using SRK/T for long eyes and Hoffer Q for short eyes, 64% achieved postoperative subjective refractions of ≤±0.25 D, 83%≤±0.50 D and 93%≤±0.75 D, with a maximum predictive error of 1.25D. No specific calculation method performed best across all ALs; however for ALs under 22 mm Hoffer Q and Holliday I methods performed best. Excellent but equivalent overall refractive results were found between all biometry methods used in this multifocal IOL study. For eyes with ALs under 22 mm Hoffer Q and Holliday I performed best. Current techniques mean that patients are still likely to need top up glasses for certain situations. Copyright © 2015 Elsevier Ltd. All rights reserved.
Kolega, Marija Škara; Kovačević, Suzana; Čanović, Samir; Pavičić, Ana Didović; Bašić, Jadranka Katušić
2015-03-01
Postoperative refractive outcome largely depends on the accuracy of calculating power of implanted IOL. Lens power calculation can be done by conventional ultrasound biometry and partial coherence laser interferometry (IOL Master). The aim was to compare the accuracy of IOL power calculations using conventional ultrasound biometry and partial coherence laser interferometry.40 eyes were included in this prospective randomized trial. Twenty eyes underwent IOL master and 20 eyes had aplanation ultrasound biometry. There were included only eyes with age-related cataract and postoperative natural visual acuity (VA) 0.7. Visual acuity was performed 6 weeks after cataract surgery. After 6 weeks best natural visual acuity were 0.9 (± 0.1) in IOL-Master group and 0.85 (± 0.15) in ultrasound biometry. The postoperative mean absolute refractive error was 0.75 (± 0.5) D for ultrasound biometry and 0.50 (± 0.50) D for IOL-Master. Optical biometry with the IOL-Master proved to be slightly more accurate than ultrasound biometry for IOL power calculation.
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Zina Zhang
2017-01-01
Full Text Available Purpose: To compare the outcomes of intraoperative wavefront aberrometry versus optical biometry alone for intraocular lens (IOL power calculation in eyes undergoing cataract surgery with monofocal IOL implantation. Methods: Preoperative data were obtained with the IOLMaster. Intraoperative aphakic measurements and IOL power calculations were obtained in some patients with the optiwave refractive analysis (ORA system. Analysis was performed to determine the accuracy of monofocal IOL power prediction and postoperative manifest refraction at 1 month of the ORA versus IOLMaster. Results: Two hundred and ninety-five eyes reviewed, 61 had only preoperative IOLMaster measurements and 234 had both IOLMaster and ORA measurements. Of these 234 eyes, 6 were excluded, 107 had the same recommended IOL power by ORA and IOLMaster. Sixty-four percent of these eyes were within ±0.5D. 95 eyes had IOL power implantation based on ORA instead of IOLMaster. Seventy percent of these eyes were within ±0.5D of target refraction. 26 eyes had IOL power chosen based on IOLMaster predictions instead of ORA. Sixty-five percent were within ±0.5D. In the group with IOLMaster without ORA measurements, 80% of eyes were within ±0.5D of target refraction. The absolute error was statistically smaller in those eyes where the ORA and IOLMaster recommended the same IOL power based on preoperative target refraction compared to instances in which IOL selection was based on ORA or IOLMaster alone. Neither prediction errors were statistically different between the ORA and IOLMaster alone. Conclusion: Intraoperative wavefront aberrometry with the ORA system provides postoperative refractive results comparable to conventional biometry with the IOLMaster for monofocal IOL selection.
Crystalline lens power and refractive error.
Iribarren, Rafael; Morgan, Ian G; Nangia, Vinay; Jonas, Jost B
2012-02-01
To study the relationships between the refractive power of the crystalline lens, overall refractive error of the eye, and degree of nuclear cataract. All phakic participants of the population-based Central India Eye and Medical Study with an age of 50+ years were included. Calculation of the refractive lens power was based on distance noncycloplegic refractive error, corneal refractive power, anterior chamber depth, lens thickness, and axial length according to Bennett's formula. The study included 1885 subjects. Mean refractive lens power was 25.5 ± 3.0 D (range, 13.9-36.6). After adjustment for age and sex, the standardized correlation coefficients (β) of the association with the ocular refractive error were highest for crystalline lens power (β = -0.41; P lens opacity grade (β = -0.42; P lens power (β = -0.95), lower corneal refractive power (β = -0.76), higher lens thickness (β = 0.30), deeper anterior chamber (β = 0.28), and less marked nuclear lens opacity (β = -0.05). Lens thickness was significantly lower in eyes with greater nuclear opacity. Variations in refractive error in adults aged 50+ years were mostly influenced by variations in axial length and in crystalline lens refractive power, followed by variations in corneal refractive power, and, to a minor degree, by variations in lens thickness and anterior chamber depth.
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Ashish Mitra
2014-01-01
Full Text Available Efficacy of intraocular lens power calculation formulas in a subset of Indian myopic population. Retrospectively reviewed 43 patients who underwent phacoemulsification with high axial length (AL (>24.5 mm, range 24.75-32.35 mm. The power of the implanted intraocular lens (IOL was used to calculate the predicted post-operative refractive error by four formulas: Sanders-Retzlaff-Kraff (SRK II, SRK/T, Holladay 1, and Hoffer Q. The predictive accuracy of the formulas was analyzed by comparing the difference between the "actual" and "predicted" postoperative refractive errors. Repeated measures analysis of variance (ANOVA tests were done to have pair-wise comparisons between the formulas and P < 0.05 was considered significant. A subcategory of axial length 24.5-26.5 mm was also tested. Holladay 1, Hoffer Q and SRK/T formulas showed a slight tendency toward resultant hyperopia, with mean error of +0.24 diopters (D, +0.58 D, and +0.92 D, respectively. The Holladay 1 formula provided the best predictive result overall.
Kirgiz, Ahmet; Atalay, Kurşat; Kaldirim, Havva; Cabuk, Kubra Serefoglu; Akdemir, Mehmet Orcun; Taskapili, Muhittin
2017-08-01
The purpose of this study was to compare the keratometry (K) values obtained by the Scheimpflug camera combined with placido-disk corneal topography (Sirius) and optical biometry (Lenstar) for intraocular lens (IOL) power calculation before the cataract surgery, and to evaluate the accuracy of postoperative refraction. 50 eyes of 40 patients were scheduled to have phacoemulsification with the implantation of a posterior chamber intraocular lens. The IOL power was calculated using the SRK/T formula with Lenstar K and K readings from Sirius. Simulated K (SimK), K at 3-, 5-, and 7-mm zones from Sirius were compared with Lenstar K readings. The accuracy of these parameters was determined by calculating the mean absolute error (MAE). The mean Lenstar K value was 44.05 diopters (D) ±1.93 (SD) and SimK, K at 3-, 5-, and 7-mm zones were 43.85 ± 1.91, 43.88 ± 1.9, 43.84 ± 1.9, 43.66 ± 1.85 D, respectively. There was no statistically significant difference between the K readings (P = 0.901). When Lenstar was used for the corneal power measurements, MAE was 0.42 ± 0.33 D, but when simK of Sirius was used, it was 0.37 ± 0.32 D (the lowest MAE (0.36 ± 0.32 D) was achieved as a result of 5 mm K measurement), but it was not statistically significant (P = 0.892). Of all the K readings of Sirius and Lenstar, Sirius 5-mm zone K readings were the best in predicting a more precise IOL power. The corneal power measurements with the Scheimpflug camera combined with placido-disk corneal topography can be safely used for IOL power calculation.
Kaswin, Godefroy; Rousseau, Antoine; Mgarrech, Mohamed; Barreau, Emmanuel; Labetoulle, Marc
2014-04-01
To evaluate the agreement in axial length (AL), keratometry (K), anterior chamber depth (ACD) measurements; intraocular lens (IOL) power calculations; and predictability using a new partial coherence interferometry (PCI) optical biometer (AL-Scan) and a reference (gold standard) PCI optical biometer (IOLMaster 500). Service d'Ophtalmologie, Hopital Bicêtre, APHP Université, Paris, France. Evaluation of a diagnostic device. One eye of consecutive patients scheduled for cataract surgery was measured. Biometry was performed with the new biometer and the reference biometer. Comparisons were performed for AL, average K at 2.4 mm, ACD, IOL power calculations with the Haigis and SRK/T formulas, and postoperative predictability of the devices. A P value less than 0.05 was statistically significant. The study enrolled 50 patients (mean age 72.6 years±4.2 SEM). There was a good correlation between biometers for AL, K, and ACD measurements (r=0.999, r=0.933, and r=0.701, respectively) and between IOL power calculation with the Haigis formula (r=0.972) and the SRK/T formula (r=0.981). The mean absolute error (MAE) in IOL power prediction was 0.42±0.08 diopter (D) with the new biometer and 0.44±0.08 D with the reference biometer. The MAE was 0.20 D with the Haigis formula and 0.19 with the SRK/T formula (P=.36). The new PCI biometer provided valid measurements compared with the current gold standard, indicating that the new device can be used for IOL power calculations for routine cataract surgery. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
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Khambhiphant B
2016-07-01
Full Text Available Bharkbhum Khambhiphant,1 Suganlaya Sasiwilasagorn,2 Nattida Chatbunchachai,3 Krit Pongpirul2,4 1Department of Ophthalmology, King Chulalongkorn Memorial Hospital, Thai Red Cross Society, 2Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University, Bangkok, 3Department of Ophthalmology, Samut Prakan Hospital, Samut Prakan, Thailand; 4Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA Purpose: The purpose of this study was to evaluate the effect of pupillary dilation on the Haigis formula-calculated intraocular lens (IOL power and ocular biometry measurements by using IOLMaster®. Methods: A prospective study was performed for biometry measurements of 373 eyes of 192 healthy subjects using the IOLMaster at the outpatient department of King Chulalongkorn Memorial Hospital from February 2013 to July 2013. The axial length (AL, anterior chamber depth (ACD, keratometry (K, and IOL power were measured before and after 1% tropicamide eye drop instillation. The Haigis formula was used in the IOL power calculation with the predicted target to emmetropia. Each parameter was compared by a paired t-test prior to and after pupillary dilation. Bland–Altman plots were also used to determine the agreement between each parameter. Results: The mean age of the subjects was 53.74±14.41 years (range 18–93 years. No differences in AL (P=0.03, steepest K (P=0.42, and flattest K (P=0.41 were obtained from the IOLMaster after pupillary dilation. However, ACD and IOL power were significantly different postdilation (P<0.01 and P<0.01, respectively. In ACD and IOL power measurements, the concordance rates were 93.03% and 97.05% within 95% limits of agreement (-0.48 to 0.26 mm and -1.09 to 0.88 D, respectively in the Bland–Altman plots. Conclusion: Biometry measurements in the cycloplegic stage should be considered in the IOL formulas that use parameters other than AL and K. Keywords: Haigis
Karunaratne, Nicholas
2013-12-01
To compare the accuracy of the Pentacam Holladay equivalent keratometry readings with the IOL Master 500 keratometry in calculating intraocular lens power. Non-randomized, prospective clinical study conducted in private practice. Forty-five consecutive normal patients undergoing cataract surgery. Forty-five consecutive patients had Pentacam equivalent keratometry readings at the 2-, 3 and 4.5-mm corneal zone and IOL Master keratometry measurements prior to cataract surgery. For each Pentacam equivalent keratometry reading zone and IOL Master measurement the difference between the observed and expected refractive error was calculated using the Holladay 2 and Sanders, Retzlaff and Kraff theoretic (SRKT) formulas. Mean keratometric value and mean absolute refractive error. There was a statistically significantly difference between the mean keratometric values of the IOL Master, Pentacam equivalent keratometry reading 2-, 3- and 4.5-mm measurements (P variance). There was no statistically significant difference between the mean absolute refraction error for the IOL Master and equivalent keratometry readings 2 mm, 3 mm and 4.5 mm zones for either the Holladay 2 formula (P = 0.14) or SRKT formula (P = 0.47). The lowest mean absolute refraction error for Holladay 2 equivalent keratometry reading was the 4.5 mm zone (mean 0.25 D ± 0.17 D). The lowest mean absolute refraction error for SRKT equivalent keratometry reading was the 4.5 mm zone (mean 0.25 D ± 0.19 D). Comparing the absolute refraction error of IOL Master and Pentacam equivalent keratometry reading, best agreement was with Holladay 2 and equivalent keratometry reading 4.5 mm, with mean of the difference of 0.02 D and 95% limits of agreement of -0.35 and 0.39 D. The IOL Master keratometry and Pentacam equivalent keratometry reading were not equivalent when used only for corneal power measurements. However, the keratometry measurements of the IOL Master and Pentacam equivalent keratometry reading 4.5 mm may be
Odenthal, M.T.; Eggink, C.A.; Melles, G.R.J.; Pameyer, J.H.; Geerards, A.J.; Beekhuis, W.H.
2002-01-01
OBJECTIVES: To describe the refractive results of cataract surgery after photorefractive keratectomy (PRK) for patients with myopia, and to find a more accurate method to predict intraocular lens (IOL) power in these cases. DESIGN: Nonrandomized, retrospective clinical study. PATIENTS AND METHODS:
Huang, David; Tang, Maolong; Wang, Li; Zhang, Xinbo; Armour, Rebecca L.; Gattey, Devin M.; Lombardi, Lorinna H.; Koch, Douglas D.
2013-01-01
Purpose: To use optical coherence tomography (OCT) to measure corneal power and improve the selection of intraocular lens (IOL) power in cataract surgeries after laser vision correction. Methods: Patients with previous myopic laser vision corrections were enrolled in this prospective study from two eye centers. Corneal thickness and power were measured by Fourier-domain OCT. Axial length, anterior chamber depth, and automated keratometry were measured by a partial coherence interferometer. An OCT-based IOL formula was developed. The mean absolute error of the OCT-based formula in predicting postoperative refraction was compared to two regression-based IOL formulae for eyes with previous laser vision correction. Results: Forty-six eyes of 46 patients all had uncomplicated cataract surgery with monofocal IOL implantation. The mean arithmetic prediction error of postoperative refraction was 0.05 ± 0.65 diopter (D) for the OCT formula, 0.14 ± 0.83 D for the Haigis-L formula, and 0.24 ± 0.82 D for the no-history Shammas-PL formula. The mean absolute error was 0.50 D for OCT compared to a mean absolute error of 0.67 D for Haigis-L and 0.67 D for Shammas-PL. The adjusted mean absolute error (average prediction error removed) was 0.49 D for OCT, 0.65 D for Haigis-L (P=.031), and 0.62 D for Shammas-PL (P=.044). For OCT, 61% of the eyes were within 0.5 D of prediction error, whereas 46% were within 0.5 D for both Haigis-L and Shammas-PL (P=.034). Conclusions: The predictive accuracy of OCT-based IOL power calculation was better than Haigis-L and Shammas-PL formulas in eyes after laser vision correction. PMID:24167323
Intraocular lens calculations in atypical eyes
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Aazim A Siddiqui
2017-01-01
Full Text Available Cataract surgery is the most performed surgical procedure in the field of ophthalmology. The process of intraocular lens (IOL calculations is a critical step to achieving successful outcomes. Many IOL formulae exist to guide surgeons through the difficult process of picking the most appropriate lens to achieve a certain target refraction. However, these formulae reach within 0.50 diopters of the target refraction only 75% of the time, leaving 25% of the eyes with a significant refractive surprise. A literature review was performed to investigate all the relevant published material on the history, progress, and recent advancements of IOL calculations. Based on this review, the appropriate history, evolution, progress, limitations, and recent advancements are analyzed and explained. Although the modern IOL formulae and biometric devices perform well for average eyes, they are suboptimal for eyes with atypical biometric parameters and also those that are postrefractive and keratoconic. There has not been a single, perfect formula that can resolve the complexities of this process. Various methods of formula optimization and newer generation of IOL formulae and devices may hold the key to improving outcomes in both typical and atypical eyes. These solutions minimize refractive error by introducing new input parameters and complex mathematical techniques to better estimate postoperative lens position.
Effect of infusion bottle height on lens power after lens refilling with and without a plug
Koopmans, SA; Terwee, T; Haitjema, HJ; Kooijman, AC; Barkhof, J
2003-01-01
Purpose: To evaluate the influence of intraoperative infusion bottle height on the power of refilled pig lenses. Setting: Research Laboratory, Pharmacia Intraocular Lens Manufacturing Plant, Groningen, The Netherlands. Methods: This study comprised 2 groups of pig eyes. In 1 group, the lens was
Cataract and keratoconus: minimizing complications in intraocular lens calculations.
Bozorg, Sara; Pineda, Roberto
2014-01-01
Patients with both cataract and keratoconus present unique challenges for the surgeon. Accurate keratometry (K) and axial length (AL) readings may be impossible, and uncertainty is introduced when estimating the corneal power for intraocular lens (IOL) selection. Different options on how to choose an IOL and how to manage irregular astigmatism of a keratoconic patient with cataract have been proposed and are reviewed. The stage of keratoconus and the history of the patient are both critical in determining the strategy used in treatment of cataracts.
Vortexlike Power Flow at the Interfaces of Metamaterial Lens
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K. Fang
2012-10-01
Full Text Available The metamaterial lens with DPS/DNS/DPS structure has been realized by using the two-dimensional (2D isotropic transmission line approach. We studied the vortexlike power flow at the interfaces of metamaterial lens and validated by the finite-difference time-domain (FDTD simulator. The computational results showing its different conditions near DPS/DNS and other kinds of interfaces are obtained by CST STUDIO SUITE at different frequencies, and demonstrate the intuitionistic power location at the metamaterial lens interfaces.
Refractive power and biometric properties of the nonhuman primate isolated crystalline lens.
Borja, David; Manns, Fabrice; Ho, Arthur; Ziebarth, Noel M; Acosta, Ana Carolina; Arrieta-Quintera, Esdras; Augusteyn, Robert C; Parel, Jean-Marie
2010-04-01
Purpose. To characterize the age dependence of shape, refractive power, and refractive index of isolated lenses from nonhuman primates. Methods. Measurements were performed on ex vivo lenses from cynomolgus monkeys (cyno: n = 120; age, 2.7-14.3 years), rhesus monkeys (n = 61; age, 0.7-13.3 years), and hamadryas baboons (baboon: n = 16; age, 1.7-27.3 years). Lens thickness, diameter, and surface curvatures were measured with an optical comparator. Lens refractive power was measured with a custom optical system based on the Scheiner principle. The refractive contributions of the gradient, the surfaces, and the equivalent refractive index were calculated with optical ray-tracing software. The age dependence of the optical and biometric parameters was assessed. Results. Over the measured age range isolated lens thickness decreased (baboon: -0.04, cyno: -0.05, and rhesus: -0.06 mm/y) and equatorial diameter increased (logarithmically for the baboon and rhesus, and linearly for cyno: 0.07 mm/y). The isolated lens surfaces flattened and the corresponding refractive power from the surfaces decreased with age (-0.33, -0.48, and -0.68 D/y). The isolated lens equivalent refractive index decreased (only significant for the baboon, -0.001 D/y), and as a result the total isolated lens refractive power decreased with age (baboon: -1.26, cyno: -0.97, and rhesus: -1.76 D/y). Conclusions. The age-dependent trends in the optical and biometric properties, growth, and aging, of nonhuman primate lenses are similar to those of the pre-presbyopic human lens. As the lens ages, the decrease in refractive contributions from the gradient refractive index causes a rapid age-dependent decrease in maximally accommodated lens refractive power.
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David P Piñero
2015-01-01
Full Text Available Purpose: To evaluate the predictability of the refractive correction achieved with a positional accommodating intraocular lenses (IOL and to develop a potential optimization of it by minimizing the error associated with the keratometric estimation of the corneal power and by developing a predictive formula for the effective lens position (ELP. Materials and Methods: Clinical data from 25 eyes of 14 patients (age range, 52-77 years and undergoing cataract surgery with implantation of the accommodating IOL Crystalens HD (Bausch and Lomb were retrospectively reviewed. In all cases, the calculation of an adjusted IOL power (P IOLadj based on Gaussian optics considering the residual refractive error was done using a variable keratometric index value (n kadj for corneal power estimation with and without using an estimation algorithm for ELP obtained by multiple regression analysis (ELP adj . P IOLadj was compared to the real IOL power implanted (P IOLReal , calculated with the SRK-T formula and also to the values estimated by the Haigis, HofferQ, and Holladay I formulas. Results: No statistically significant differences were found between P IOLReal and P IOLadj when ELP adj was used (P = 0.10, with a range of agreement between calculations of 1.23 D. In contrast, P IOLReal was significantly higher when compared to P IOLadj without using ELP adj and also compared to the values estimated by the other formulas. Conclusions: Predictable refractive outcomes can be obtained with the accommodating IOL Crystalens HD using a variable keratometric index for corneal power estimation and by estimating ELP with an algorithm dependent on anatomical factors and age.
Metallic plates lens focalizing a high power microwave beam
International Nuclear Information System (INIS)
Rebuffi, L.
1987-08-01
A metallic grating composed of thin parallel plates opportunely spaced, permits to correct the phase of an incident high power microwave beam. In this work we show how it is possible to obtain a beam focalisation (lens), a beam deflection (prisma), or a variation in the polarization (polarizer) using parallel metallic plates. The main design parameters are here presented, in order to obtain the wanted phase modification keeping low the diffraction, the reflected power, the ohmic losses and avoiding breakdowns. Following the given criteria, a metallic plate lens has been realized to focalize the 200 KW, 100 msec 60 GHz beam used in the ECRH experiment on the TFR tokamak. The experimental beam concentration followed satisfactory the design requirements. In fact, the maximum intensity increased about twice the value without lens. In correspondence of this distance a reduction of the beam size of about 50% have been measured for the -3 dB radius. The lens supported high power tests without breakdowns or increase of the reflected power
Kawamura, Marenori; Sato, Susumu
2018-05-01
The variable range of lens power of a liquid-crystal (LC) lens driven by two voltages is discussed on the basis of calculated and experimental results. The LC lens has two electrodes, which are a circularly hole-patterned electrode and a circular electrode, in addition to a common electrode, and highly resistive transparent films. The variable range of lens power increases with increasing driving voltage applied across the circularly hole-patterned electrode and the common electrode, and with decreasing diameter of highly resistive films. However, the optical-phase retardation profile tends to deviate from a parabolic curve in these cases. As a method to improve the trade-off properties, the highly resistive film is divided into two regions with different diameters, where the sheet resistance of an outer film is larger than that of an inner one. The improved LC lens has a lens power that varies in a wide range, and it exhibits a good parabolic phase retardation profile.
An Exact Formula for Calculating Inverse Radial Lens Distortions
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Pierre Drap
2016-06-01
Full Text Available This article presents a new approach to calculating the inverse of radial distortions. The method presented here provides a model of reverse radial distortion, currently modeled by a polynomial expression, that proposes another polynomial expression where the new coefficients are a function of the original ones. After describing the state of the art, the proposed method is developed. It is based on a formal calculus involving a power series used to deduce a recursive formula for the new coefficients. We present several implementations of this method and describe the experiments conducted to assess the validity of the new approach. Such an approach, non-iterative, using another polynomial expression, able to be deduced from the first one, can actually be interesting in terms of performance, reuse of existing software, or bridging between different existing software tools that do not consider distortion from the same point of view.
Xiong, Shuyu; Zhang, Bo; Hong, Yuan; He, Xiangui; Zhu, Jianfeng; Zou, Haidong; Xu, Xun
2017-11-01
To investigate the relationship between lens power and age as well as the relationship between lens power and axial length (AL) in Chinese children and adolescents. The participants underwent a comprehensive ophthalmic examination that included AL, cycloplegic refraction, and Pentacam measurements. The crystalline lens power was calculated using Bennett's formula and then compared among the children of different age groups, refractive statuses, and AL categories. The association of lens power and AL was analyzed using multiple regression. A total of 1992 children and adolescents aged 6- to 18-years old were included. The difference in lens power was greater before 10-years old, followed by a relatively smaller difference in children aged 10 to 14 years and the difference in lens power came to a near plateau in adolescents after 14-years old. The negative association between lens power and AL was found to be more evident in nonmyopes than in myopes irrespective of age (younger than 10 years: nonmyopes: β = -1.499, myopes: β = -0.872; older than 10 years: nonmyopes: β = -1.288, myopes: β = -0.390, all P power in children and adolescents aged 6 to 18 years exhibited three stages. The association between lens power and AL differed between the nonmyopes and myopes. These findings suggested that less reduction in lens power might be associated with both growing age and increasing AL in myopes.
Which soft lens power is better for piggyback in keratoconus? Part II.
Romero-Jiménez, Miguel; Santodomingo-Rubido, Jacinto; González-Meijóme, Jose-Manuel; Flores-Rodriguez, Patricia; Villa-Collar, Cesar
2015-02-01
To evaluate how soft lens power affects rigid gas-permeable (RGP) lens power and visual acuity (VA) in piggyback fittings for keratoconus. Sixteen keratoconus subjects (30 eyes) were included in the study. Piggyback contact lens fittings combining Senofilcon-A soft lenses of -6.00, -3.00, +3.00 and +6.00 D with Rose K2 RGP contact lenses were performed. Corneal topography was taken on the naked eye and over each soft contact lens before fitting RGP lenses. Mean central keratometry, over-refraction, RGP back optic zone radius (BOZR) and estimated final power as well as VA were recorded and analyzed. In comparison to the naked eye, the mean central keratometry flattened with both negative lens powers (psoft lens power (p=1.0); and steepened with the +6.00 soft lens power (p=0.02). Rigid gas-permeable over-refraction did not change significantly between different soft lens powers (all p>0.05). RGP's BOZR decreased significantly with both positive in comparison with both negative soft lens powers (all ppowers separately (both p>0.05). Estimated RGP's final power increased significantly with positive in comparison with negative lens powers (all ppowers separately (both p>0.05). Visual acuity did not change significantly between the different soft lens powers assessed (all p>0.05). The use of negative-powered soft lenses in piggyback fitting reduces RGP lens power without impacting VA in keratoconus subjects. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Catur Apriono
2015-08-01
Full Text Available A terahertz system uses dielectric lens antennas for focusing and collimating beams of terahertz wave radiation. Linearly polarized terahertz wave radiation has been widely applied in the terahertz system. Therefore, an accurate method for analyzing the power flow density in the dielectric lens antenna irradiated with the linearly polarized terahertz wave radiation is important to design the terahertz systems. In optics, ray-tracing method has been used to calculate the power flow density by a number density of rays. In this study, we propose a method of ray-tracing combined with Fresnel’s transmission, including transmittance and polarization of the terahertz wave radiation to calculate power flow density in a Silicon lens antenna. We compare power flow density calculated by the proposed method with the regular ray-tracing method. When the Silicon lens antenna is irradiated with linearly polarized terahertz wave radiation, the proposed method calculates the power flow density more accurately than the regular ray-tracing.
The overall phase shift and lens effect calculation using Gaussian ...
Indian Academy of Sciences (India)
In this work, the inhomogeneous equation of heat conduction was exactly ... for those pump spot sizes for which the Rayleigh range is much greater than the .... The curvature will be accompanied by a focusing power depending on whether the.
Abelman, Herven; Abelman, Shirley
2014-01-01
Unacceptable principal powers in well-centred lenses may require a toric over-refraction which differs in nature from the one where correct powers have misplaced meridians. This paper calculates residual (over) refractions and their natures. The magnitude of the power of the over-refraction serves as a general, reliable, real scalar criterion for acceptance or tolerance of lenses whose surface relative curvatures change or whose meridians are rotated and cause powers to differ. Principal powers and meridians of lenses are analogous to eigenvalues and eigenvectors of symmetric matrices, which facilitates the calculation of powers and their residuals. Geometric paths in symmetric power space link intended refractive correction and these carefully chosen, undue refractive corrections. Principal meridians alone vary along an arc of a circle centred at the origin and corresponding powers vary autonomously along select diameters of that circle in symmetric power space. Depending on the path of the power change, residual lenses different from their prescription in principal powers and meridians are pure cross-cylindrical or spherocylindrical in nature. The location of residual power in symmetric dioptric power space and its optical cross-representation characterize the lens that must be added to the compensation to attain the power in the prescription.
Intraocular lens calculation adjustment after laser refractive surgery using Scheimpflug imaging.
Schuster, Alexander K; Schanzlin, David J; Thomas, Karin E; Heichel, Christopher W; Purcell, Tracy L; Barker, Patrick D
2016-02-01
To test a new method of intraocular lens (IOL) calculation after corneal refractive surgery using Scheimpflug imaging (Pentacam HR) and partial coherence interferometry (PCI) (IOLMaster) that does not require historical data; that is, the Schuster/Schanzlin-Thomas-Purcell (SToP) IOL calculator. Shiley Eye Center, San Diego, California, and Walter Reed National Military Medical Center, Bethesda, Maryland, USA. Retrospective data analysis and validation study. Data were retrospectively collected from patient charts including data from Scheimpflug imaging and refractive history. Target refraction was calculated using PCI and the Holladay 1 and SRK/T formulas. Regression analysis was performed to explain the deviation of the target refraction, taking into account the following influencing factors: ratio of posterior-to-anterior corneal radius, axial length (AL), and anterior corneal radius. The regression analysis study included 61 eyes (39 patients) that had laser in situ keratomileusis (57 eyes) or photorefractive keratectomy (4 eyes) and subsequent cataract. Two factors were found that explained the deviation of the target refraction using the Holladay 1 formula; that is, the ratio of the corneal radii and the AL and the ratio of corneal radii for the SRK/T formula. A new IOL adjustment calculator was derived and validated at a second center using 14 eyes (10 patients). The error in IOL calculation for normal eyes after laser refractive treatment was related to the ratio of posterior-to-anterior corneal radius. A formula requiring Scheimpflug data and suggested IOL power only yielded an improved postoperative result for patients with previous corneal laser refractive surgery having cataract surgery. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. All rights reserved.
Anomalies in the prescribing of soft contact lens power.
Young, Graeme; Moody, Kurt; Sulley, Anna
2009-01-01
To determine the proportion of prescribed soft lenses rounded to the nearest half diopter and any variations from country to country and between lens types. Marketing data were obtained for soft lenses supplied during a 1-year period for lenses representing each of the following categories: mid-water hydrogel (MWH), silicone hydrogel, daily disposable, and toric silicone hydrogel (TSH). The data were analyzed for several countries/regions. Spherical lenses were analyzed in the range 1.00 to 5.75 D for plus and minus powers, and toric lenses in the range 0.50 to 5.75 D. This ensured a similar number of lenses in full or half diopter powers were compared with quarter and three-quarter diopter powers, and that there was no enforced rounding due to nonavailability of powers. By comparing the proportion of lenses from the 2 power groups, the proportion of lenses rounded to the nearest half diopter was estimated. It was assumed that half the difference between the totals of the 2 power groups represented those lenses dispensed to the nearest half diopter and, therefore, dispensed inaccurately; this was termed the "rounding rate" (RR). The power distribution curve for the sphere powers spiked in half diopter steps, illustrated a bias toward prescribing full and half diopter powers. With all lenses, the RR varied widely between countries. For the MWH, this ranged from 1.7% (Canada) to 11.6% (Iberia). The RRs were 2 to 3 times higher for plus than minus power lenses, however, this also varied by country. Overall, the RRs were lower for the silicone hydrogel and daily disposable contact lenses compared with the MWH, in particular for France and Iberia. The TSH results showed the greatest consistency between countries, with RRs ranging from 3.9% (Germany) to 9.5% (Rest of Europe). Most countries showed similar or lower RRs for TSH compared with MWH although, for some countries (e.g., United Kingdom, Nordic), these were higher. There was less difference in RRs for TSH lenses
Power Matters: Foucault's "Pouvoir/Savoir" as a Conceptual Lens in Information Research and Practice
Olsson, Michael; Heizmann, Helena
2015-01-01
Introduction: This paper advocates Foucault's notion of pouvoir/savoir (power/knowledge) as a conceptual lens that information researchers might fruitfully use to develop a richer understanding of the relationship between knowledge and power. Methods: Three of the authors' earlier studies are employed to illustrate the use of this conceptual lens.…
Piñero, David P; Camps, Vicente J; Ramón, María L; Mateo, Verónica; Pérez-Cambrodí, Rafael J
2015-01-01
To evaluate the prediction error in intraocular lens (IOL) power calculation for a rotationally asymmetric refractive multifocal IOL and the impact on this error of the optimization of the keratometric estimation of the corneal power and the prediction of the effective lens position (ELP). Retrospective study including a total of 25 eyes of 13 patients (age, 50 to 83y) with previous cataract surgery with implantation of the Lentis Mplus LS-312 IOL (Oculentis GmbH, Germany). In all cases, an adjusted IOL power (PIOLadj) was calculated based on Gaussian optics using a variable keratometric index value (nkadj) for the estimation of the corneal power (Pkadj) and on a new value for ELP (ELPadj) obtained by multiple regression analysis. This PIOLadj was compared with the IOL power implanted (PIOLReal) and the value proposed by three conventional formulas (Haigis, Hoffer Q and Holladay I). PIOLReal was not significantly different than PIOLadj and Holladay IOL power (P>0.05). In the Bland and Altman analysis, PIOLadj showed lower mean difference (-0.07 D) and limits of agreement (of 1.47 and -1.61 D) when compared to PIOLReal than the IOL power value obtained with the Holladay formula. Furthermore, ELPadj was significantly lower than ELP calculated with other conventional formulas (P<0.01) and was found to be dependent on axial length, anterior chamber depth and Pkadj. Refractive outcomes after cataract surgery with implantation of the multifocal IOL Lentis Mplus LS-312 can be optimized by minimizing the keratometric error and by estimating ELP using a mathematical expression dependent on anatomical factors.
Directory of Open Access Journals (Sweden)
David P. Piñero
2015-06-01
Full Text Available AIM:To evaluate the prediction error in intraocular lens (IOL power calculation for a rotationally asymmetric refractive multifocal IOL and the impact on this error of the optimization of the keratometric estimation of the corneal power and the prediction of the effective lens position (ELP.METHODS:Retrospective study including a total of 25 eyes of 13 patients (age, 50 to 83y with previous cataract surgery with implantation of the Lentis Mplus LS-312 IOL (Oculentis GmbH, Germany. In all cases, an adjusted IOL power (PIOLadj was calculated based on Gaussian optics using a variable keratometric index value (nkadj for the estimation of the corneal power (Pkadj and on a new value for ELP (ELPadj obtained by multiple regression analysis. This PIOLadj was compared with the IOL power implanted (PIOLReal and the value proposed by three conventional formulas (Haigis, Hoffer Q and Holladay Ⅰ.RESULTS:PIOLReal was not significantly different than PIOLadj and Holladay IOL power (P>0.05. In the Bland and Altman analysis, PIOLadj showed lower mean difference (-0.07 D and limits of agreement (of 1.47 and -1.61 D when compared to PIOLReal than the IOL power value obtained with the Holladay formula. Furthermore, ELPadj was significantly lower than ELP calculated with other conventional formulas (P<0.01 and was found to be dependent on axial length, anterior chamber depth and Pkadj.CONCLUSION:Refractive outcomes after cataract surgery with implantation of the multifocal IOL Lentis Mplus LS-312 can be optimized by minimizing the keratometric error and by estimating ELP using a mathematical expression dependent on anatomical factors.
Liquid lens with double tunable surfaces for large power tunability and improved optical performance
International Nuclear Information System (INIS)
Li, Lei; Wang, Qiong-Hua; Jiang, Wei
2011-01-01
In this paper we propose a liquid lens with two tunable interfaces formed by two kinds of immiscible liquids. The proposed liquid lens uses liquid pressure to change the shape of the interfaces. It can provide a large tunable range of optical power and improved optical performance. By applying suitable liquids the gravity effect can also be negligible. To prove the principles, a liquid lens with 7 mm aperture was fabricated. The optical performance indicates that the proposed liquid lens can provide a large tunable range of both positive and negative powers even using liquids with small differences in refractive indices. The resolution is better than 50 lp mm −1 under white light environment. The spherical aberration and coma are also largely reduced. The proposed liquid lens can also provide the optical designer with the freedom to choose the combination of liquids to reduce or even correct aberrations
Which soft contact lens power is better for piggyback fitting in keratoconus?
Romero-Jiménez, Miguel; Santodomingo-Rubido, Jacinto; Flores-Rodríguez, Patricia; González-Méijome, Jose Manuel
2013-02-01
To evaluate the impact of differente soft contact lens power in the anterior corneal curvature and regularity in subjects with keratoconus. Nineteen subjects (30 eyes) with keratoconus were included in the study. Six corneal topographies were taken with Pentacam Eye System over the naked eye and successively with soft lens (Senofilcon A) powers of -3.00, -1.50, 0.00, +1.50 and +3.00 D. Corneal measurements of mean central keratometry (MCK), maximum tangential curvature (TK), maximum front elevation (MFE) and eccentricity (Ecc) at 6 and 8 mm diameters as well as anterior corneal surface high order aberrations (i.e. total RMS, spherical- and coma-like and secondary astigmatism) were evaluated. Negative- and plano-powered soft lenses flattened (ppowered lenses did not induce any significant changes (p>0.05 in all cases) in MCK in comparison to the naked eye. The TK power decreased with negative lenses (psoft lens power in comparison to the naked eye (p>0.05 in all cases). Corneal eccentricity increased at 8 mm diameter for all lens powers (p0.05). Statistically differences were found in coma-like and secondary astigmatism (both ppowered soft contact lenses provide a flatter anterior surface in comparison to positive-powered lenses in subjects with keratoconus and thus they might be more suitable for piggyback contact lens fitting. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
Calculation of Wind Power Limit adjusting the Continuation Power Flow
International Nuclear Information System (INIS)
Santos Fuentefria, Ariel; Castro Fernández, Miguel; Martínez García, Antonio
2012-01-01
The wind power insertion in the power system is an important issue and can create some instability problems in voltage and system frequency due to stochastic origin of wind. Know the Wind Power Limit is a very important matter. Existing in bibliography a few methods for calculation of wind power limit. The calculation is based in static constrains, dynamic constraints or both. In this paper is developed a method for the calculation of wind power limit using some adjust in the continuation power flow, and having into account the static constrains. The method is complemented with Minimal Power Production Criterion. The method is proved in the Isla de la Juventud Electric System. The software used in the simulations was the Power System Analysis Toolbox (PSAT). (author)
Directory of Open Access Journals (Sweden)
Hsu M
2011-09-01
Full Text Available David L DeMill1, Majid Moshirfar1, Marcus C Neuffer1, Maylon Hsu1, Shameema Sikder21John A Moran Eye Center, University of Utah, Salt Lake City, UT, USA; 2Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USABackground: To compare the average values of the American Society of Cataract and Refractive Surgery (ASCRS and Ocular MD intraocular lens (IOL calculators to assess their accuracy in predicting IOL power in patients with prior laser-in-situ keratomileusis (LASIK or photorefractive keratectomy.Methods: In this retrospective study, data from 21 eyes with previous LASIK or photorefractive keratectomy for myopia and subsequent cataract surgery was used in an IOL calculator comparison. The predicted IOL powers of the Ocular MD SRK/T, Ocular MD Haigis, and ASCRS averages were compared. The Ocular MD average (composed of an average of Ocular MD SRK/T and Ocular MD Haigis and the all calculator average (composed of an average of Ocular MD SRK/T, Ocular MD Haigis, and ASCRS were also compared. Primary outcome measures were mean arithmetic and absolute IOL prediction error, variance in mean arithmetic IOL prediction error, and the percentage of eyes within ±0.50 and ±1.00 D.Results: The Ocular MD SRK/T and Ocular MD Haigis averages produced mean arithmetic IOL prediction errors of 0.57 and –0.61 diopters (D, respectively, which were significantly larger than errors from the ASCRS, Ocular MD, and all calculator averages (0.11, –0.02, and 0.02 D, respectively, all P < 0.05. There was no statistically significant difference between the methods in absolute IOL prediction error, variance, or the percentage of eyes with outcomes within ±0.50 and ±1.00 D.Conclusion: The ASCRS average was more accurate in predicting IOL power than the Ocular MD SRK/T and Ocular MD Haigis averages alone. Our methods using combinations of these averages which, when compared with the individual averages, showed a trend of decreased mean arithmetic IOL
Electron stopping powers for transport calculations
International Nuclear Information System (INIS)
Berger, M.J.
1988-01-01
The reliability of radiation transport calculations depends on the accuracy of the input cross sections. Therefore, it is essential to review and update the cross sections from time to time. Even though the main interest of the author's group at NBS is in transport calculations and their applications, the group spends almost as much time on the analysis and preparation of cross sections as on the development of transport codes. Stopping powers, photon attenuation coefficients, bremsstrahlung cross sections, and elastic-scattering cross sections in recent years have claimed attention. This chapter deals with electron stopping powers (with emphasis on collision stopping powers), and reviews the state of the art as reflected by Report 37 of the International Commission on Radiation Units and Measurements
Directory of Open Access Journals (Sweden)
David P. Piñero
2016-06-01
Full Text Available AIM: To evaluate the refractive predictability achieved with an aspheric intraocular lens(IOLand to develop a preliminary optimized algorithm for the calculation of its power(PIOL.METHODS: This study included 65 eyes implanted with the aspheric IOL LENTIS L-313(Oculentis GmbHthat were divided into 2 groups: 12 eyes(8 patientswith PIOL≥23.0 D(group A, and 53 eyes(35 patientswith PIOLIOLadjwas calculated considering a variable refractive index for corneal power estimation, the refractive outcome obtained, and an adjusted effective lens position(ELPadjaccording to age and anatomical factors. RESULTS: Postoperative spherical equivalent ranged from -0.75 to +0.75 D and from -1.38 to +0.75 D in groups A and B, respectively. No statistically significant differences were found in groups A(P=0.64and B(P=0.82between PIOLadj and the IOL power implanted(PIOLReal. The Bland and Altman analysis showed ranges of agreement between PIOLadj and PIOLReal of +1.11 to -0.96 D and +1.14 to -1.18 D in groups A and B, respectively. Clinically and statistically significant differences were found between PIOLadj and PIOL obtained with Hoffer Q and Holladay I formulas(PCONCLUSION: The refractive predictability of cataract surgery with implantation of an aspheric IOL can be optimized using paraxial optics combined with linear algorithms to minimize the error associated to the estimation of corneal power and ELP.
Intraocular lens power selection and positioning with and without intraoperative aberrometry.
Hatch, Kathryn M; Woodcock, Emily C; Talamo, Jonathan H
2015-04-01
To determine the value of intraoperative aberrometry in cases of toric intraocular lens (IOL) implantation and positioning. In this non-randomized retrospective comparative trial, two groups of eyes underwent cataract extraction with toric IOL implantation: the aberrometry group (n = 37 eyes), where toric IOL power and alignment were determined before surgery with automated keratometry, standard optical biometry, and an online calculator and then refined using intraoperative aberrometry, and the toric calculator group (n = 27 eyes), where IOL selection was performed in a similar manner but without intraoperative aberrometry. The primary outcome measure was mean postoperative residual refractive astigmatism (RRA). Mean RRA measured at follow-up after surgery was 0.46 ± 0.42 and 0.68 ± 0.34 diopters (D) in the aberrometry and toric calculator groups, respectively (P = .0153). A 75% and 57% reduction in cylinder was noted between preoperative keratometric astigmatism and postoperative RRA in the aberrometry and toric calculator groups, respectively (P = .0027). RRA of 0.25 D or less, 0.50 D or less, 0.75 D or less, and 1.00 D or less was seen 38%, 78%, 86%, and 95% of the time, respectively, in the aberrometry group and 22%, 33%, 74%, and 89% of the time, respectively, in the toric calculator group. These data show that the chance of a patient being in a lower postoperative RRA range increased when intraoperative aberrometry was used (P = .0130). Patients undergoing cataract extraction with toric IOL placement aided by intraoperative aberrometry were 2.4 times more likely to have less than 0.50 D of RRA compared to standard methods. Copyright 2015, SLACK Incorporated.
Optimal power distribution for minimizing pupil walk in a 7.5X afocal zoom lens
Song, Wanyue; Zhao, Yang; Berman, Rebecca; Bodell, S. Yvonne; Fennig, Eryn; Ni, Yunhui; Papa, Jonathan C.; Yang, Tianyi; Yee, Anthony J.; Moore, Duncan T.; Bentley, Julie L.
2017-11-01
An extensive design study was conducted to find the best optimal power distribution and stop location for a 7.5x afocal zoom lens that controls the pupil walk and pupil location through zoom. This afocal zoom lens is one of the three components in a VIS-SWIR high-resolution microscope for inspection of photonic chips. The microscope consists of an afocal zoom, a nine-element objective and a tube lens and has diffraction limited performance with zero vignetting. In this case, the required change in object (sample) size and resolution is achieved by the magnification change of the afocal component. This creates strict requirements for both the entrance and exit pupil locations of the afocal zoom to couple the two sides successfully. The first phase of the design study looked at conventional four group zoom lenses with positive groups in the front and back and the stop at a fixed location outside the lens but resulted in significant pupil walk. The second phase of the design study focused on several promising unconventional four-group power distribution designs with moving stops that minimized pupil walk and had an acceptable pupil location (as determined by the objective and tube lens).
International Nuclear Information System (INIS)
Gardes, D.; Bimbot, R.; Della-Negra, S.; Dumail, M.; Kubica, B.; Richard, A.; Rivet, M.F.; Servajean, A.; Deutsch, C.; Maynard, G.
1988-01-01
By coupling a hydrogen plasma to a Tandem accelerator, transmission and energy losses of 2 MeV/u carbon and sulfur beams passing through a plasma target have been investigated. Fluctuations in beam transmission have been observed and attributed to a plasma lens effect. Moreover, energy loss measurements indicate an enhanced stopping power of the plasma relative to its cold matter equivalent
Power calculation of grading device in desintegrator
Bogdanov, V. S.; Semikopenko, I. A.; Vavilov, D. V.
2018-03-01
This article describes the analytical method of measuring the secondary power consumption, necessitated by the installation of a grading device in the peripheral part of the grinding chamber in the desintegrator. There is a calculation model for defining the power input of the disintegrator increased by the extra power demand, required to rotate the grading device and to grind the material in the area between the external row of hammers and the grading device. The work has determined the inertia moments of a cylindrical section of the grading device with armour plates. The processing capacity of the grading device is adjusted to the conveying capacity of the auger feeder. The grading device enables one to increase the concentration of particles in the peripheral part of the grinding chamber and the amount of interaction between particles and armour plates as well as the number of colliding particles. The perforated sections provide the output of the ground material with the proper size granules, which together with the effects of armour plates, improves the efficiency of grinding. The power demand to rotate the grading device does not exceed the admissible value.
Power operation, measurement and methods of calculation of power distribution
International Nuclear Information System (INIS)
Lindahl, S.O.; Bernander, O.; Olsson, S.
1982-01-01
During the initial fuel loading of a BWR core, extensive checks and measurements of the fuel are performed. The measurements are designed to verify that the reactor can always be safely operated in compliance with the regulatory constraints. The power distribution within the reactor core is evaluated by means of instrumentation and elaborate computer calculations. The power distribution forms the basis for the evaluation of thermal limits. The behaviour of the reactor during the ordinary modes of operation as well as during transients shall be well understood and such that the integrity of the fuel and the reactor systems is always well preserved. (author)
Directory of Open Access Journals (Sweden)
W. F. Harris
2009-12-01
Full Text Available If an intraocular lens is displaced or if its power is changed what are the consequences for the refractive compensation of the eye? Gaussian optics is used to obtain explicit formulae for the sensitivityof the corneal-plane refractive compensation (also called the refraction, refractive state, etc to change in power and axial displacement of a thin intraocular lens implanted in a simple eye. In particular, for a pseudophakic Gullstrand simplified eye with intraocular lens placed 5 mm behind the cornea the sensitivity to errors in the power of the intraocular lens is about 71 . 0 − 71 for an intraocular lens of power for an intraocular lens of power 20 D, that is, the refractive compensation decreases by about 0.71 dioptres per dioptre increase in the power of the intraocular lens. More generally the sensitivity is approximately ( m 0037 . 0 63 . 0 F − − 0.63 ( 003 . 0 63 . 0 − − (0.0037mF where FI is the power of the intraocular lens. Also for Gullstrand’s simplified eye the sensitivity of refractive compensation to axial displacement of the intraocular lens is approximately linear in FI about (64D FI, in fact. That is, for each dioptre of the power of the intraocular lens the refractive compensation increases by about 0.064 dioptres per millimetre of axial displacement towards the retina.
Mechanical design of a power-adjustable spectacle lens frame.
Zapata, Asuncion; Barbero, Sergio
2011-05-01
Power-adjustable spectacle lenses, based on the Alvarez-Lohmann principle, can be used to provide affordable spectacles for subjective refractive errors measurement and its correction. A new mechanical frame has been designed to maximize the advantages of this technology. The design includes a mechanism to match the interpupillary distance with that of the optical centers of the lenses. The frame can be manufactured using low cost plastic injection molding techniques. A prototype has been built to test the functioning of this mechanical design.
Kim, Eon; Bakaraju, Ravi C; Ehrmann, Klaus
2016-01-01
To evaluate the repeatability of power profiles measured on NIMO TR1504 (Lambda-X, Belgium) and investigate the effects of lens decentration on the power profiles for single vision (SV), bifocal (BF) and multifocal (MF) contact lenses. Accuracy of the sphere power was evaluated using single vision BK-7 calibration glass lenses of six minus and six plus powers. Three SV and four BF/MF contact lenses - three lenses each, were measured five times to calculate the coefficients of repeatability (COR) of the instrument. The COR was computed for each chord position, lens design, prescription power and operator. One lens from each type was measured with a deliberate decentration up to ±0.5mm in 0.1mm steps. For all lenses, the COR varied across different regions of the half-chord position. In general, SV lenses showed lower COR compared to the BF/MF group lenses. There were no noticeable trends of COR between prescription powers for SV and BF/MF lenses. The shape of the power profiles was not affected when lenses were deliberately decentered for all SV and PureVision MF lenses. However, for Acuvue BF lenses, the peak to trough amplitude of the power profiles flattened up to 1.00D. The COR across the half-chord of the optic zone diameter was mostly within clinical relevance except for the central 0.5mm half-chord position. COR were dependent on the lens type, whereby BF/MF group produced higher COR than SV lenses. The effects of deliberate decentration on the shape of power profiles were pronounced for lenses where the profiles had sharp transitions of power. Copyright © 2015 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.
Power calculation of linear and angular incremental encoders
Prokofev, Aleksandr V.; Timofeev, Aleksandr N.; Mednikov, Sergey V.; Sycheva, Elena A.
2016-04-01
Automation technology is constantly expanding its role in improving the efficiency of manufacturing and testing processes in all branches of industry. More than ever before, the mechanical movements of linear slides, rotary tables, robot arms, actuators, etc. are numerically controlled. Linear and angular incremental photoelectric encoders measure mechanical motion and transmit the measured values back to the control unit. The capabilities of these systems are undergoing continual development in terms of their resolution, accuracy and reliability, their measuring ranges, and maximum speeds. This article discusses the method of power calculation of linear and angular incremental photoelectric encoders, to find the optimum parameters for its components, such as light emitters, photo-detectors, linear and angular scales, optical components etc. It analyzes methods and devices that permit high resolutions in the order of 0.001 mm or 0.001°, as well as large measuring lengths of over 100 mm. In linear and angular incremental photoelectric encoders optical beam is usually formulated by a condenser lens passes through the measuring unit changes its value depending on the movement of a scanning head or measuring raster. Past light beam is converting into an electrical signal by the photo-detecter's block for processing in the electrical block. Therefore, for calculating the energy source is a value of the desired value of the optical signal at the input of the photo-detecter's block, which reliably recorded and processed in the electronic unit of linear and angular incremental optoelectronic encoders. Automation technology is constantly expanding its role in improving the efficiency of manufacturing and testing processes in all branches of industry. More than ever before, the mechanical movements of linear slides, rotary tables, robot arms, actuators, etc. are numerically controlled. Linear and angular incremental photoelectric encoders measure mechanical motion and
Bogdanoff, David W.; Berschauer, Andrew; Parker, Timothy W.; Vickers, Jesse E.
1989-01-01
A vortex gas lens concept is presented. Such a lens has a potential power density capability of 10 to the 9th - 10 to the 10th w/sq cm. An experimental prototype was constructed, and the divergence half angle of the exiting beam was measured as a function of the lens operating parameters. Reasonably good agreement is found between the experimental results and theoretical calculations. The expanded beam was observed to be steady, and no strong, potentially beam-degrading jets were found to issue from the ends of the lens. Estimates of random beam deflection angles to be expected due to boundary layer noise are presented; these angles are very small.
Workplace Ostracism Seen through the Lens of Power
Fiset, John; Al Hajj, Raghid; Vongas, John G.
2017-01-01
Drawing on approach/inhibition theory of power, we investigated two factors that influence the manner by which victims react to workplace ostracism: the hierarchical status of the ostracizer and the level of an ostracizee’s external social support including family, friends, and significant others. Across an experimental vignette study (Study 1) and a field study (Study 2), we found support for a three-way interaction with felt ostracism, ostracizee external social support, and ostracizer status influencing victims’ organizational citizenship behavior and deviance directed toward other individuals. In addition, felt ostracism and ostracizee external social support interacted to predict turnover intentions. Overall, victims who were ostracized by a legitimate higher-status authority (e.g., manager) and whose external social support network was limited experienced the most negative outcomes across both studies. Our findings suggest that contextual factors both inside and outside the organization jointly impact the way in which individuals react to perceived workplace ostracism. Implications and future research directions are discussed. PMID:28928702
Workplace Ostracism Seen through the Lens of Power
Directory of Open Access Journals (Sweden)
John Fiset
2017-09-01
Full Text Available Drawing on approach/inhibition theory of power, we investigated two factors that influence the manner by which victims react to workplace ostracism: the hierarchical status of the ostracizer and the level of an ostracizee’s external social support including family, friends, and significant others. Across an experimental vignette study (Study 1 and a field study (Study 2, we found support for a three-way interaction with felt ostracism, ostracizee external social support, and ostracizer status influencing victims’ organizational citizenship behavior and deviance directed toward other individuals. In addition, felt ostracism and ostracizee external social support interacted to predict turnover intentions. Overall, victims who were ostracized by a legitimate higher-status authority (e.g., manager and whose external social support network was limited experienced the most negative outcomes across both studies. Our findings suggest that contextual factors both inside and outside the organization jointly impact the way in which individuals react to perceived workplace ostracism. Implications and future research directions are discussed.
Workplace Ostracism Seen through the Lens of Power.
Fiset, John; Al Hajj, Raghid; Vongas, John G
2017-01-01
Drawing on approach/inhibition theory of power, we investigated two factors that influence the manner by which victims react to workplace ostracism: the hierarchical status of the ostracizer and the level of an ostracizee's external social support including family, friends, and significant others. Across an experimental vignette study (Study 1) and a field study (Study 2), we found support for a three-way interaction with felt ostracism, ostracizee external social support, and ostracizer status influencing victims' organizational citizenship behavior and deviance directed toward other individuals. In addition, felt ostracism and ostracizee external social support interacted to predict turnover intentions. Overall, victims who were ostracized by a legitimate higher-status authority (e.g., manager) and whose external social support network was limited experienced the most negative outcomes across both studies. Our findings suggest that contextual factors both inside and outside the organization jointly impact the way in which individuals react to perceived workplace ostracism. Implications and future research directions are discussed.
International Nuclear Information System (INIS)
Akahane, Keiichi; Tatsuzaki, Hideo; Iimoto, Takeshi; Ichiji, Takeshi; Hamada, Nobuyuki; Iwai, Satoshi; Ohguchi, Hiroyuki; Ohno, Kazuko; Katoh, Masahiro; Kurosawa, Tadahiro; Kawaura, Chiyo; Tsujimura, Norio; Hayashida, Toshiyuki; Hotta, Yutaka; Yamasaki, Tadashi; Yokoyama, Sumi
2015-01-01
The Expert Committee on Radiation Protection of the Lens of the Eye was established under the Japan Health Physics Society in April, 2013 (completed, March, 2015). The Committee looked at new/revised documents and standards related to the eye lens published by international organizations such as the International Commission on Radiological Protection (ICRP) and the International Commission on Radiation Units and Measurements (ICRU). The Committee also examined recent and previous studies related to eye-lens radiation exposure and dosimetry in Japan. These findings were published in this journal as the Interim Report of the Committee. Since then, the Committee expanded its activity to give an overview the current progress of eye-lens dosimetry R and D at the National Institute of Advanced Industrial Science and Technology, along with research related to radiation management and estimated eye-lens exposure of Japanese nuclear-power-plant workers (including those at Fukushima Daiichi Nuclear Power Plant) for publishing an addendum Committee report. These additional findings are reported here. (author)
International Nuclear Information System (INIS)
Carinou, E.; Ferrari, P.; Koukorava, C.; Krim, S.; Struelens, L.
2011-01-01
There are many factors that can influence the extremity and eye lens doses of the medical staff during interventional radiology and cardiology procedures. Numerical simulations can play an important role in evaluating extremity and eye lens doses in correlation with many different parameters. In the present study, the first results of the ORAMED (Optimisation of Radiation protection of Medical staff) simulation campaign are presented. The parameters investigated for their influence on eye lens, hand, wrist and leg doses are: tube voltage, filtration, beam projection, field size and irradiated part of the patient's body. The tube voltage ranged from 60 to 110 kVp, filtration from 3 to 6 mm Al and from 0 to 0.9 mm Cu. For all projections, the results showed that doses received by the operator decreased with increasing tube voltage and filtration. The magnitude of the influence of the tube voltage and the filtration on the doses depends on the beam projection and the irradiated part of the patient's body. Finally, the influence of the field size is significant in decreasing the doses. (authors)
Numerical Calculation of Overhead Power Lines Dynamics
Directory of Open Access Journals (Sweden)
Gogola Roman
2016-11-01
Full Text Available This paper contains results of transient analysis of airflow around the ACSR power line cross-section in unsymmetric multi-span. The forces applied to the power line are obtained from CFD simulations, where the wind induced vibration is studied. Effect of these forces to the maximal displacement of the power line and the maximal mechanical forces in the points of attachment are studied and evaluated.
Calculation of power density with MCNP in TRIGA reactor
International Nuclear Information System (INIS)
Snoj, L.; Ravnik, M.
2006-01-01
Modern Monte Carlo codes (e.g. MCNP) allow calculation of power density distribution in 3-D geometry assuming detailed geometry without unit-cell homogenization. To normalize MCNP calculation by the steady-state thermal power of a reactor, one must use appropriate scaling factors. The description of the scaling factors is not adequately described in the MCNP manual and requires detailed knowledge of the code model. As the application of MCNP for power density calculation in TRIGA reactors has not been reported in open literature, the procedure of calculating power density with MCNP and its normalization to the power level of a reactor is described in the paper. (author)
Benchmark calculations of power distribution within assemblies
International Nuclear Information System (INIS)
Cavarec, C.; Perron, J.F.; Verwaerde, D.; West, J.P.
1994-09-01
The main objective of this Benchmark is to compare different techniques for fine flux prediction based upon coarse mesh diffusion or transport calculations. We proposed 5 ''core'' configurations including different assembly types (17 x 17 pins, ''uranium'', ''absorber'' or ''MOX'' assemblies), with different boundary conditions. The specification required results in terms of reactivity, pin by pin fluxes and production rate distributions. The proposal for these Benchmark calculations was made by J.C. LEFEBVRE, J. MONDOT, J.P. WEST and the specification (with nuclear data, assembly types, core configurations for 2D geometry and results presentation) was distributed to correspondents of the OECD Nuclear Energy Agency. 11 countries and 19 companies answered the exercise proposed by this Benchmark. Heterogeneous calculations and homogeneous calculations were made. Various methods were used to produce the results: diffusion (finite differences, nodal...), transport (P ij , S n , Monte Carlo). This report presents an analysis and intercomparisons of all the results received
Site response calculations for nuclear power plants
International Nuclear Information System (INIS)
Wight, L.H.
1975-01-01
Six typical sites consisting of three soil profiles with average shear wave velocities of 800, 1800, and 5000 ft/sec as well as two soil depths of 200 and 400 ft were considered. Seismic input to these sites was a synthetic accelerogram applied at the surface and corresponding to a statistically representative response spectrum. The response of each of these six sites to this input was calculated with the SHAKE program. The results of these calculations are presented
Measurement of Crystalline Lens Volume During Accommodation in a Lens Stretcher.
Marussich, Lauren; Manns, Fabrice; Nankivil, Derek; Maceo Heilman, Bianca; Yao, Yue; Arrieta-Quintero, Esdras; Ho, Arthur; Augusteyn, Robert; Parel, Jean-Marie
2015-07-01
To determine if the lens volume changes during accommodation. The study used data acquired on 36 cynomolgus monkey lenses that were stretched in a stepwise fashion to simulate disaccommodation. At each step, stretching force and dioptric power were measured and a cross-sectional image of the lens was acquired using an optical coherence tomography system. Images were corrected for refractive distortions and lens volume was calculated assuming rotational symmetry. The average change in lens volume was calculated and the relation between volume change and power change, and between volume change and stretching force, were quantified. Linear regressions of volume-power and volume-force plots were calculated. The mean (± SD) volume in the unstretched (accommodated) state was 97 ± 8 mm3. On average, there was a small but statistically significant (P = 0.002) increase in measured lens volume with stretching. The mean change in lens volume was +0.8 ± 1.3 mm3. The mean volume-power and volume-load slopes were -0.018 ± 0.058 mm3/D and +0.16 ± 0.40 mm3/g. Lens volume remains effectively constant during accommodation, with changes that are less than 1% on average. This result supports a hypothesis that the change in lens shape with accommodation is accompanied by a redistribution of tissue within the capsular bag without significant compression of the lens contents or fluid exchange through the capsule.
Cheng, H W; Jeng, B M; Chen, C Y; Huang, H Y; Chiou, J C; Luo, C H
2013-01-01
This paper proposed a wireless power harvesting system with micro-electro-mechanical-systems (MEMS) fabrication for noninvasive intraocular pressure (IOP) measurement on soft contact lens substructure. The power harvesting IC consists of a loop antenna, an impedance matching network and a rectifier. The proposed IC has been designed and fabricated by CMOS 0.18 um process that operates at the ISM band of 5.8 GHz. The antenna and the power harvesting IC would be bonded together by using flip chip bonding technologies without extra wire interference. The circuit utilized an impedance transformation circuit to boost the input RF signal that improves the circuit performance. The proposed design achieves an RF-to-DC conversion efficiency of 35% at 5.8 GHz.
Numerical Calculation of the Output Power of a MHD Generator
Directory of Open Access Journals (Sweden)
Adrian CARABINEANU
2014-12-01
Full Text Available Using Lazăr Dragoş’s analytic solution for the electric potential we perform some numerical calculations in order to find the characteristics of a Faraday magnetohydrodymamics (MHD power generator (total power, useful power and Joule dissipation power.
Calculation of transients in WWER power plant
International Nuclear Information System (INIS)
Macek, J.; Kyncl, M.
1981-01-01
A mathematical model is described for the computation of transient processes in a nuclear power plant as is the DYNAMIKA computer program. The program is used for computing two accident variants: rupture of the main steam collector and a failure of the main circulating pump. (H.S.)
Dietze, Holger H; Cox, Michael J
2003-02-01
Soft contact lenses produce a significant level of spherical aberration affecting their power on-eye. A simple model assuming that a thin soft contact lens aligns to the cornea predicts that these effects are similar on-eye and off-eye. The wavefront aberration for 17 eyes and 33 soft contact lenses on-eye was measured with a Shack-Hartmann wavefront sensor. The Zernike coefficients describing the on-eye spherical aberration of the soft contact lens were compared with off-eye ray-tracing results. Paraxial and effective lens power changes were determined. The model predicts the on-eye spherical aberration of soft contact lenses closely. The resulting power change for a +/- 7.00 D spherical soft contact lens is +/- 0.5 D for a 6-mm pupil diameter and +/- 0.1 D for a 3-mm pupil diameter. Power change is negligible for soft contact lenses corrected for off-eye spherical aberration. For thin soft contact lenses, the level of spherical aberration and the consequent power change is similar on-eye and off-eye. Soft contact lenses corrected for spherical aberration in air will be expected to be aberration-free on-eye and produce only negligibly small power changes. For soft contact lenses without aberration correction, for higher levels of ametropia and large pupils, the soft contact lens power should be determined with trial lenses with their power and p value similar to the prescribed lens. The benefit of soft contact lenses corrected for spherical aberration depends on the level of ocular spherical aberration.
Calculated CIM Power Distributions for Coil Design
International Nuclear Information System (INIS)
Hardy, B.J.
1999-01-01
Excessive bed expansion and material expulsion have occurred during experiments with the 3-inch diameter Cylindrical Induction Melter (CIM). Both events were attributed in part to the high power density in the bottom of the melter and the correspondingly high temperatures there. It is believed that the high temperatures resulted in the generation of gasses at the bottom of the bed which could not escape. The gasses released during heating and the response of the bed to gas evolution depend upon the composition of the bed
Gonçalves, Ricardo; Carvalho, Nuno B.; Pinho, Pedro
2017-02-01
In the current contest of wireless systems, the last frontier remains the cut of the power cord. In that sense, the interest over wireless energy transfer technologies in the past years has grown exponentially. However, there are still many challenges to be overcome in order to enable wireless energy transfer full potential. One of the focus in the development of such systems is the design of very-high-gain, highly efficient, antennas that can compensate for the propagation loss of radio signals over the air. In this paper, we explore the design and manufacturing process of dielectric lenses, fabricated using a professional-grade desktop 3D printer. Lens antennas are used in order to increase beam efficiency and therefore maximize the efficiency of a wireless power-transfer system operating at microwave frequencies in the Ku band. Measurements of two fabricated prototypes showcase a large directivity, as predicted with simulations. xml:lang="fr"
Directory of Open Access Journals (Sweden)
Lu Zhang
2013-10-01
Full Text Available AIM: To evaluate the clinical feasibility of using a new optical coherence interferometry(IOL-Master, comparing with traditional ultrasonic biometry and manual keratometry in the accuracy and characteristics for intraocular lens calculation of high myopia.METHODS: The measurement of axial length was performed in 60 eyes(30 eyes for each groupwith senile cataract of high myopia(≥-6.00Dusing IOL-Master and ultrasonic biometry. The measurement of corneal power(Kwas also performed in the patient using IOL-Master and manual keratometry preoperatively. Phacoemulsification and foldable lens implantation were done on the patients. IOL power calculation was carried out according to the SRK/T formula on the basis of the group-related data. Best corrected visual acuity, refraction, contrast sensitivity and wave front aberration root mean square(RMSwere re-tested after 3 months postoperatively.RESULTS: Significant difference between the two methods in axial length measurement which was 29.81±1.53mm by ultrasound and 29.63±1.81mm by IOL-Master(P=0.001. And in corneal power measurement which was 43.22±1.67K by manual keratometry and 44.27±1.39K by IOL-Master(P=0.006. There was a significant difference between the two groups(P=0.001. 63.0% vs 31.2% had a mean absolute refractive error(MAREwithin ±0.50 diopter for the IOL-Master and A-scan groups, respectively(χ2=3.1, Pth order aberration, 4th order spherical aberration and total high order aberration in the IOL-Master group were lower than those in the A-scan group at 6mm pupil diameter 3 months later. CONCLUSION: IOL-Master is a non-contact, accurate, safe and reliable tool for calculating IOL power and it is more accurate on the design of the IOL in the cataract surgery on the high myopia patients.
Reconstruction calculation of pin power for ship reactor core
International Nuclear Information System (INIS)
Li Haofeng; Shang Xueli; Chen Wenzhen; Wang Qiao
2010-01-01
Aiming at the limitation of the software that pin power distribution for ship reactor core was unavailable, the calculation model and method of the axial and radial pin power distribution were proposed. Reconstruction calculations of pin power along axis and radius was carried out by bicubic and bilinear interpolation and cubic spline interpolation, respectively. The results were compared with those obtained by professional reactor physical soft with fine mesh difference. It is shown that our reconstruction calculation of pin power is simple and reliable as well as accurate, which provides an important theoretic base for the safety analysis and operating administration of the ship nuclear reactor. (authors)
Calculation device for fuel power history in BWR type reactors
International Nuclear Information System (INIS)
Sakagami, Masaharu.
1980-01-01
Purpose: To enable calculations for power history and various variants of power change in the power history of fuels in a BWR type reactor or the like. Constitution: The outputs of the process computation for the nuclear reactor by a process computer are stored and the reactor core power distribution is judged from the calculated values for the reactor core power distribution based on the stored data. Data such as for thermal power, core flow rate, control rod position and power distribution are recorded where the changes in the power distribution exceed a predetermined amount, and data such as for thermal power and core flow rate are recorded where the changes are within the level of the predetermined amount, as effective data excluding unnecessary data. Accordingly, the recorded data are taken out as required and the fuel power history and the various variants in the fuel power are calculated and determined in a calculation device for fuel power history and variants for fuel power fluctuation. (Furukawa, Y.)
Crystalline lens and refractive development.
Iribarren, Rafael
2015-07-01
Individual refractive errors usually change along lifespan. Most children are hyperopic in early life. This hyperopia is usually lost during growth years, leading to emmetropia in adults, but myopia also develops in children during school years or during early adult life. Those subjects who remain emmetropic are prone to have hyperopic shifts in middle life. And even later, at older ages, myopic shifts are developed with nuclear cataract. The eye grows from 15 mm in premature newborns to approximately 24 mm in early adult years, but, in most cases, refractions are maintained stable in a clustered distribution. This growth in axial length would represent a refractive change of more than 40 diopters, which is compensated by changes in corneal and lens powers. The process which maintains the balance between the ocular components of refraction during growth is still under study. As the lens power cannot be measured in vivo, but can only be calculated based on the other ocular components, there have not been many studies of lens power in humans. Yet, recent studies have confirmed that the lens loses power during growth in children, and that hyperopic and myopic shifts in adulthood may be also produced by changes in the lens. These studies in children and adults give a picture of the changing power of the lens along lifespan. Other recent studies about the growth of the lens and the complexity of its internal structure give clues about how these changes in lens power are produced along life. Copyright © 2015 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Hayashida, Toshiyuki; Sasaki, Hiroshi; Hatsusaka, Natsuko; Hamada, Nobuyuki; Tatsuzaki, Hideo; Akahane, Keiichi; Yokoyama, Sumi
2017-01-01
In March 2011, the accident occurred at the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company. During recovery from critical situations, the radiation dose for some emergency workers exceeded the effective dose limit recommended for an emergency situation. A month after the accident, the International Commission on Radiological Protection issued a statement on tissue reactions recommending significant reduction of the equivalent dose limit to the lens of the eye. Many radiation workers will need to be involved in treatment of water contaminated with radionuclides, fuel debris retrieval, and decommissioning of reactors for a long period of time. Thus, the optimized radiation control in the fields, exposure reduction, prevention of tissue reactions, and reduction of stochastic risks for workers becomes necessary. This paper discusses issues in relation to radiation protection of the ocular lens in such recovery workers, from the viewpoint of radiation exposure of workers, its management, manifestations and mechanisms of the lens effects. (author)
Maeng, Sung Jun; Kim, Jinhwan; Cho, Gyuseong
2018-03-15
ICRP (2011) revised the dose limit to the eye lens to 20 mSv/y based on a recent epidemiological study of radiation-induced cataracts. Maintenance of steam generators at nuclear power plants is one of the highest radiation-associated tasks within a non-uniform radiation field. This study aims to evaluate eye lens doses in the steam generators of the Korean OPR1000 design. The source term was characterized based on the CRUD-specific activity, and both the eye lens dose and organ dose were simulated using MCNP6 combined with an ICRP voxel phantom and a mesh phantom, respectively. The eye lens dose was determined to be 5.39E-02-9.43E-02 Sv/h, with a negligible effect by beta particles. As the effective dose was found to be 0.81-1.21 times the lens equivalent dose depending on the phantom angles, the former can be used to estimate the lens dose in the SG of the OPR1000 for radiation monitoring purposes.
Sedaghat, Mohammad Reza; Azimi, Ali; Arasteh, Peyman; Tehranian, Naghmeh; Bamdad, Shahram
2016-10-01
Basic anatomical parameters in ophthalmology are variable in different countries according to ethnic groups, genetics and some environmental factors. The aim of this study was to determine the relationship between axial length (AL), anterior chamber depth (ACD) and intraocular lens power (IOL) in a referral center from eastern Iran among patients who had cataract surgery, in comparison to studies from other regions of the world. In a cross-sectional retrospective study from 2011 to 2013, the records of 698 cataract patients referring to Khatam Al Anbia general hospital in Mashhad, Iran were evaluated. We divided patients, based on their AL and ACD, into three separate groups and compared their results. The SPSS software was used for data analysis. The Chi-Square test and the Independent-samples t-test were used to compare qualitative and quantitative data between two groups, respectively. The Kendall and the Pearson product-moment correlation tests were used to assess the relationship between AL and ACD. The linear Regression model was used to obtain a mathematical model to estimate ACD, using AL, age and sex. Among individuals who had normal AL (between 22-24.5mm), there was a positive correlation between AL and ACD (p24.5mm), no significant correlation was detected. We also found that older people have shorter AL (p=0.001 and r=-0.287). Men have an average longer AL (23.7±2.4mm vs. 22.9±2.1mm; pworld and although some anatomical variations may exist regarding ophthalmic anatomy, factors like race and geographical area have little effect on the relationship between ACD, AL and IOL power calculation, furthermore our results support the use of third and fourth generation formulas for IOL power calculation.
Power calculator for instrumental variable analysis in pharmacoepidemiology.
Walker, Venexia M; Davies, Neil M; Windmeijer, Frank; Burgess, Stephen; Martin, Richard M
2017-10-01
Instrumental variable analysis, for example with physicians' prescribing preferences as an instrument for medications issued in primary care, is an increasingly popular method in the field of pharmacoepidemiology. Existing power calculators for studies using instrumental variable analysis, such as Mendelian randomization power calculators, do not allow for the structure of research questions in this field. This is because the analysis in pharmacoepidemiology will typically have stronger instruments and detect larger causal effects than in other fields. Consequently, there is a need for dedicated power calculators for pharmacoepidemiological research. The formula for calculating the power of a study using instrumental variable analysis in the context of pharmacoepidemiology is derived before being validated by a simulation study. The formula is applicable for studies using a single binary instrument to analyse the causal effect of a binary exposure on a continuous outcome. An online calculator, as well as packages in both R and Stata, are provided for the implementation of the formula by others. The statistical power of instrumental variable analysis in pharmacoepidemiological studies to detect a clinically meaningful treatment effect is an important consideration. Research questions in this field have distinct structures that must be accounted for when calculating power. The formula presented differs from existing instrumental variable power formulae due to its parametrization, which is designed specifically for ease of use by pharmacoepidemiologists. © The Author 2017. Published by Oxford University Press on behalf of the International Epidemiological Association
Decay Power Calculation for Safety Analysis of Innovative Reactor Systems
Energy Technology Data Exchange (ETDEWEB)
Shwageraus, E.; Fridman, E. [Department of Nuclear Engineering, Ben-Gurion University of the Negev Beer-Sheva 84105 (Israel)
2008-07-01
In this work, we verified the decay heat calculation capabilities of BGCore computer code system developed recently at Ben-Gurion University. Decay power was calculated for a typical UO{sub 2} fuel in Pressurized Water Reactor environment using BGCore code and using procedure prescribed by the ANS/ANSI-2005 standard. Very good agreement between the two methods was obtained. Once BGCore calculation capabilities were verified, we calculated decay power as a function of time after shutdown for various reactors with innovative fuels, for which no standard procedure is currently available. Notable differences were observed for decay power of the advanced reactors as compared with conventional UO{sub 2} LWR. The observed differences suggest that the design of new reactors safety systems must be based on corresponding decay power curves for each individual case in order to assure the desired performance of such systems. (authors)
Decay Power Calculation for Safety Analysis of Innovative Reactor Systems
International Nuclear Information System (INIS)
Shwageraus, E.; Fridman, E.
2008-01-01
In this work, we verified the decay heat calculation capabilities of BGCore computer code system developed recently at Ben-Gurion University. Decay power was calculated for a typical UO 2 fuel in Pressurized Water Reactor environment using BGCore code and using procedure prescribed by the ANS/ANSI-2005 standard. Very good agreement between the two methods was obtained. Once BGCore calculation capabilities were verified, we calculated decay power as a function of time after shutdown for various reactors with innovative fuels, for which no standard procedure is currently available. Notable differences were observed for decay power of the advanced reactors as compared with conventional UO 2 LWR. The observed differences suggest that the design of new reactors safety systems must be based on corresponding decay power curves for each individual case in order to assure the desired performance of such systems. (authors)
Formation for the calculation of reactivity without nuclear power history
International Nuclear Information System (INIS)
Suescun Diaz, Daniel; Senra Martinez, Aquilino; Carvalho Da Silva, Fernando
2007-01-01
This paper presents a new method for the solution of the inverse point kinetics equation. This method is based on the integration by parts of the integral of the inverse point kinetics equation, which results in a power series in terms of the nuclear power in time dependence. With the imposition of conditions to the nuclear power, the reactivity is represented as first and second derivatives of this nuclear power. This new calculation method for reactivity has very special characteristics, amongst which the possibility of using longer sampling period, and the possibility of restarting the calculation, after its interruption, allowing the calculation of reactivity in a non-continuous way. Beside that, the reactivity can be obtained independent of the nuclear power memory. (author)
Methods for tornado frequency calculation of nuclear power plant
International Nuclear Information System (INIS)
Liu Haibin; Li Lin
2012-01-01
In order to take probabilistic safety assessment of nuclear power plant tornado attack event, a method to calculate tornado frequency of nuclear power plant is introduced based on HAD 101/10 and NUREG/CR-4839 references. This method can consider history tornado frequency of the plant area, construction dimension, intensity various along with tornado path and area distribution and so on and calculate the frequency of different scale tornado. (authors)
Calculation of power spectra for block coded signals
DEFF Research Database (Denmark)
Justesen, Jørn
2001-01-01
We present some improvements in the procedure for calculating power spectra of signals based on finite state descriptions and constant block size. In addition to simplified calculations, our results provide some insight into the form of the closed expressions and to the relation between the spect...
Calculations for accidents in water reactors during operation at power
International Nuclear Information System (INIS)
Blanc, H.; Dutraive, P.; Fabrega, S.; Millot, J.P.
1976-07-01
The behaviour of a water reactor on an accident occurring as the reactor is normally operated at power may be calculated through the computer code detailed in this article. Reactivity accidents, loss of coolant ones and power over-running ones are reviewed. (author)
The calculation of the field of the three-electrode transaxial lens
Directory of Open Access Journals (Sweden)
Duseinova A.G.
2017-04-01
Full Text Available the article offered method of the calculation of the transaxial fields based on the partition of the potential into two terms. The main term is a harmonic function of two variables and satisfies the given boundary conditions. The harmonic component of the potential is found analytically using the methods of complex analysis. The second term is the solution of an inhomogeneous equation with zero Dirichlet boundary conditions and can be found numerically with the required accuracy.
Methodology for calculating power consumption of planetary mixers
Antsiferov, S. I.; Voronov, V. P.; Evtushenko, E. I.; Yakovlev, E. A.
2018-03-01
The paper presents the methodology and equations for calculating the power consumption necessary to overcome the resistance of a dry mixture caused by the movement of cylindrical rods in the body of a planetary mixer, as well as the calculation of the power consumed by idling mixers of this type. The equations take into account the size and physico-mechanical properties of mixing material, the size and shape of the mixer's working elements and the kinematics of its movement. The dependence of the power consumption on the angle of rotation in the plane perpendicular to the axis of rotation of the working member is presented.
Whole core calculations of power reactors by Monte Carlo method
International Nuclear Information System (INIS)
Nakagawa, Masayuki; Mori, Takamasa
1993-01-01
Whole core calculations have been performed for a commercial size PWR and a prototype LMFBR by using vectorized Monte Carlo codes. Geometries of cores were precisely represented in a pin by pin model. The calculated parameters were k eff , control rod worth, power distribution and so on. Both multigroup and continuous energy models were used and the accuracy of multigroup approximation was evaluated through the comparison of both results. One million neutron histories were tracked to considerably reduce variances. It was demonstrated that the high speed vectorized codes could calculate k eff , assembly power and some reactivity worths within practical computation time. For pin power and small reactivity worth calculations, the order of 10 million histories would be necessary. Required number of histories to achieve target design accuracy were estimated for those neutronic parameters. (orig.)
Effects of resonator input power on Kerr lens mode-locked lasers
Indian Academy of Sciences (India)
lasers. S KAZEMPOUR, A KESHAVARZ∗ and G HONARASA. Department of Physics, Faculty of Sciences, Shiraz University of Technology, Shiraz, Iran ... Keywords. Femtosecond pulses; Kerr lens sensitivity; Kerr lens mode-locked laser. ... The optical lengths of Kerr medium with thickness d and refractive index n under.
Statistic method of research reactors maximum permissible power calculation
International Nuclear Information System (INIS)
Grosheva, N.A.; Kirsanov, G.A.; Konoplev, K.A.; Chmshkyan, D.V.
1998-01-01
The technique for calculating maximum permissible power of a research reactor at which the probability of the thermal-process accident does not exceed the specified value, is presented. The statistical method is used for the calculations. It is regarded that the determining function related to the reactor safety is the known function of the reactor power and many statistically independent values which list includes the reactor process parameters, geometrical characteristics of the reactor core and fuel elements, as well as random factors connected with the reactor specific features. Heat flux density or temperature is taken as a limiting factor. The program realization of the method discussed is briefly described. The results of calculating the PIK reactor margin coefficients for different probabilities of the thermal-process accident are considered as an example. It is shown that the probability of an accident with fuel element melting in hot zone is lower than 10 -8 1 per year for the reactor rated power [ru
Neutron energy spectra calculations in the low power research reactor
International Nuclear Information System (INIS)
Omar, H.; Khattab, K.; Ghazi, N.
2011-01-01
The neutron energy spectra have been calculated in the fuel region, inner and outer irradiation sites of the zero power research reactor using the MCNP-4C code and the combination of the WIMS-D/4 transport code for generation of group constants and the three-dimensional CITATION diffusion code for core analysis calculations. The neutron energy spectrum has been divided into three regions and compared with the proposed empirical correlations. The calculated thermal and fast neutron fluxes in the low power research reactor MNSR inner and outer irradiation sites have been compared with the measured results. Better agreements have been noticed between the calculated and measured results using the MCNP code than those obtained by the CITATION code. (author)
Scoping calculations of power sources for nuclear electric propulsion
International Nuclear Information System (INIS)
Difilippo, F.C.
1994-05-01
This technical memorandum describes models and calculational procedures to fully characterize the nuclear island of power sources for nuclear electric propulsion. Two computer codes were written: one for the gas-cooled NERVA derivative reactor and the other for liquid metal-cooled fuel pin reactors. These codes are going to be interfaced by NASA with the balance of plant in order to making scoping calculations for mission analysis
Reactivity calculation with reduction of the nuclear power fluctuations
International Nuclear Information System (INIS)
Suescun Diaz, Daniel; Senra Martinez, Aquilino
2009-01-01
A new formulation is presented in this paper for the calculation of reactivity, which is simpler than the formulation that uses the Laplace and Z transforms. A treatment is also made to reduce the intensity of the noise found in the nuclear power signal used in the calculation of reactivity. Two classes of different filters are used for that. This treatment is based on the fact that the reactivity can be written by using the compose Simpson's rule resulting in a sum of two convolution terms with response to the impulse that is characteristic of a linear system. The linear part is calculated by using the filter named finite impulse response filter (FIR). The non-linear part is calculated using the filter exponentially adjusted by the least squares method, which does not cause attenuation in the reactivity calculation.
Reactivity calculation with reduction of the nuclear power fluctuations
Energy Technology Data Exchange (ETDEWEB)
Suescun Diaz, Daniel [COPPE/UFRJ, Programa de Engenharia Nuclear, Caixa Postal 68509, CEP 21941-914 RJ (Brazil)], E-mail: dsuescun@hotmail.com; Senra Martinez, Aquilino [COPPE/UFRJ, Programa de Engenharia Nuclear, Caixa Postal 68509, CEP 21941-914 RJ (Brazil)
2009-05-15
A new formulation is presented in this paper for the calculation of reactivity, which is simpler than the formulation that uses the Laplace and Z transforms. A treatment is also made to reduce the intensity of the noise found in the nuclear power signal used in the calculation of reactivity. Two classes of different filters are used for that. This treatment is based on the fact that the reactivity can be written by using the compose Simpson's rule resulting in a sum of two convolution terms with response to the impulse that is characteristic of a linear system. The linear part is calculated by using the filter named finite impulse response filter (FIR). The non-linear part is calculated using the filter exponentially adjusted by the least squares method, which does not cause attenuation in the reactivity calculation.
The "Gravity-Powered Calculator," a Galilean Exhibit
Cerreta, Pietro
2014-01-01
The Gravity-Powered Calculator is an exhibit of the Exploratorium in San Francisco. It is presented by its American creators as an amazing device that extracts the square roots of numbers, using only the force of gravity. But if you analyze his concept construction one can not help but recall the research of Galileo on falling bodies, the inclined…
Houilleres du Bassin de Lorraine - calculation of AFC drive power
Energy Technology Data Exchange (ETDEWEB)
1979-01-01
Calculation method drawn up as a result of a test programme carried out by the CoRT working group on 'Coal and dirt clearance from the face - Face-ends' on 5 faces in the H.B.L. Describes the features of the conveyors. Presents a general formula for calculating the power requirement; how this is applied. Sets forth the experimental method for determining the formula coefficients plus annotations. Includes a table summarizing the various power factors (measured and theoretically calculated). Concludes that from the proposed methods, the best is that used by Potasses d'Alsace, on condition that certain of the coefficients are empirically validated. Includes a table giving features of the workings and the conveyors used.
Theoretical model for calculation of molecular stopping power
International Nuclear Information System (INIS)
Xu, Y.J.
1984-01-01
A modified local plasma model based on the work of Linhard-Winther, Bethe, Brown, and Walske is established. The Gordon-Kim's molecular charged density model is employed to obtain a formula to evaluate the stopping power of many useful molecular systems. The stopping power of H 2 and He gas was calculated for incident proton energy ranging from 100 KeV to 2.5 MeV. The stopping power of O 2 , N 2 , and water vapor was also calculated for incident proton energy ranging from 40 keV to 2.5 MeV. Good agreement with experimental data was obtained. A discussion of molecular effects leading to departure from Bragg's rule is presented. The equipartition rule and the effect of nuclear momentum recoiling in stopping power are also discussed in the appendix. The calculation procedure presented hopefully can easily be extended to include the most useful organic systems such as the molecules composed of carbon, nitrogen, hydrogen and oxygen which are useful in radiation protection field
Impedance calculations for power cables to primary coolant pump motors
International Nuclear Information System (INIS)
Hegerhorst, K.B.
1977-01-01
The LOFT primary system motor generator sets are located in Room B-239 and are connected to the primary coolant pumps by means of a power cable. The calculated average impedance of this cable is 0.005323 ohms per unit resistance and 0.006025 ohms per unit reactance based on 369.6 kVA and 480 volts. The report was written to show the development of power cable parameters that are to be used in the SICLOPS (Simulation of LOFT Reactor Coolant Loop Pumping System) digital computer program as written in LTR 1142-16 and also used in the pump coastdowns for the FSAR Analysis
Vu, Lien T; Chen, Chao-Chang A; Yu, Chia-Wei
2018-02-05
This study aims to develop a new optical design method of soft multifocal contact lens (CLs) to obtain uniform optical power in large center-distance zone with optimized Non-Uniform Rational B-spline (NURBS). For the anterior surface profiles of CLs, the NURBS design curves are optimized to match given optical power distributions. Then, the NURBS in the center-distance zones are fitted in the corresponding spherical/aspheric curves for both data points and their centers of curvature to achieve the uniform power. Four cases of soft CLs have been manufactured by casting in shell molds by injection molding and then measured to verify the design specifications. Results of power profiles of these CLs are concord with the given clinical requirements of uniform powers in larger center-distance zone. The developed optical design method has been verified for multifocal CLs design and can be further applied for production of soft multifocal CLs.
International Nuclear Information System (INIS)
Ximen Jiye; Liu Zhixiong
2000-01-01
In the present paper, Gaussian optical property in the bi-potential electrostatic and the bell-shaped magnetic combined lens - a new theoretical model first proposed in electron optics - has been thoroughly studied. Meanwhile, based on electron optical canonical aberration theory, analytical formulas of third-order geometrical and first-order chromatic aberration coefficients and their computational results have first been derived for this bi-potential electrostatic and bell-shaped magnetic combined lens. It is to emphasized that this theoretical study can be used to estimate third-order geometric and first-order chromatic aberrations and to provide a theoretical criterion for numerical computation in a rotationally symmetric electromagnetic lens
Method of calculating heat transfer in furnaces of small power
Directory of Open Access Journals (Sweden)
Khavanov Pavel
2016-01-01
Full Text Available This publication presents the experiences and results of generalization criterion equation of importance in the analysis of the processes of heat transfer and thermal calculations of low-power heat generators cooled combustion chambers. With generalizing depending estimated contribution of radiation and convective heat transfer component in the complex for the combustion chambers of small capacity boilers. Determined qualitative and quantitative dependence of the integrated radiative-convective heat transfer from the main factors working combustion chambers of small volume.
Correlation expansion: a powerful alternative multiple scattering calculation method
International Nuclear Information System (INIS)
Zhao Haifeng; Wu Ziyu; Sebilleau, Didier
2008-01-01
We introduce a powerful alternative expansion method to perform multiple scattering calculations. In contrast to standard MS series expansion, where the scattering contributions are grouped in terms of scattering order and may diverge in the low energy region, this expansion, called correlation expansion, partitions the scattering process into contributions from different small atom groups and converges at all energies. It converges faster than MS series expansion when the latter is convergent. Furthermore, it takes less memory than the full MS method so it can be used in the near edge region without any divergence problem, even for large clusters. The correlation expansion framework we derive here is very general and can serve to calculate all the elements of the scattering path operator matrix. Photoelectron diffraction calculations in a cluster containing 23 atoms are presented to test the method and compare it to full MS and standard MS series expansion
Sensitivity Calculation of Vanadium Self-Powered Neutron Detector
International Nuclear Information System (INIS)
Cha, Kyoon Ho
2011-01-01
Self-powered neutron detector (SPND) is being widely used to monitor the reactor core of the nuclear power plants. The SPND contains a neutron-sensitive metallic emitter surrounded by a ceramic insulator. Currently, the rhodium SPND has been used in many nuclear power plants. The lifetime of rhodium is too short (about 3∼5 years) to operate the nuclear power plant economically. The vanadium (V) SPND is also primarily sensitive to neutrons like rhodium, but is a somewhat slower reaction time as that of a rhodium SPND. The benefit of vanadium over rhodium is its low depletion rate, which is a factor of 7 times less than that of rhodium. For this reason, a vanadium SPND has been being developed to replace the rhodium SPND which is used in OPR1000. Some Monte Carlo simulations were accomplished to calculate the initial sensitivity of vanadium emitter material and alumina (Al 2 O 3 ) insulator with a cylindrical geometry. An MCNP-X code was used to simulate some factors (neutron self shielding factor and electron escape probability from the emitter) necessary to calculate the sensitivity of vanadium detector. The simulation results were compared with some theoretical and experimental values. The method presented here can be used to analyze the optimum design of the vanadium SPND
Calculating the Responses of Self-Powered Radiation Detectors.
Thornton, D. A.
Available from UMI in association with The British Library. The aim of this research is to review and develop the theoretical understanding of the responses of Self -Powered Radiation Detectors (SPDs) in Pressurized Water Reactors (PWRs). Two very different models are considered. A simple analytic model of the responses of SPDs to neutrons and gamma radiation is presented. It is a development of the work of several previous authors and has been incorporated into a computer program (called GENSPD), the predictions of which have been compared with experimental and theoretical results reported in the literature. Generally, the comparisons show reasonable consistency; where there is poor agreement explanations have been sought and presented. Two major limitations of analytic models have been identified; neglect of current generation in insulators and over-simplified electron transport treatments. Both of these are developed in the current work. A second model based on the Explicit Representation of Radiation Sources and Transport (ERRST) is presented and evaluated for several SPDs in a PWR at beginning of life. The model incorporates simulation of the production and subsequent transport of neutrons, gamma rays and electrons, both internal and external to the detector. Neutron fluxes and fuel power ratings have been evaluated with core physics calculations. Neutron interaction rates in assembly and detector materials have been evaluated in lattice calculations employing deterministic transport and diffusion methods. The transport of the reactor gamma radiation has been calculated with Monte Carlo, adjusted diffusion and point-kernel methods. The electron flux associated with the reactor gamma field as well as the internal charge deposition effects of the transport of photons and electrons have been calculated with coupled Monte Carlo calculations of photon and electron transport. The predicted response of a SPD is evaluated as the sum of contributions from individual
International Nuclear Information System (INIS)
Petrov, P.V.; Kolchevsky, N.N.
2013-01-01
Model of the refractive neutron lens is proposed. System of N lenses acts as one thin lens with a complex refraction index n*. The maximum number N max of individual lenses for 'thick' neutron lens is calculated. Refractive neutron lens properties (resolution, focal depth) as function of resolution factor F 0 =ρbc/μ and depth of field factor dF 0 =λF 0 =λρbc/μ are calculated. It is shown that micro resolution of the refractive neutron optics is far from the wavelength in size and its open possibilities for progress in refractive neutron optics. (authors)
Calculation of Industrial Power Systems Containing Induction Motors
Directory of Open Access Journals (Sweden)
Gheorghe Hazi
2014-09-01
Full Text Available The current paper proposes two methods and algorithms for determining the operating regimes of industrial electrical networks which include induction motors. The two methods presented are based on specific principles for calculating electrical networks: Newton-Raphson and Backward-Forward for iteratively determining currents and voltages. The particularity of this paper is how the driven load influences the determination of the motors operating regimes. For the industrial machines driven by motors we take into account the characteristic of the resistant torque depending on speed. In this way, at the electrical busbars to which motors are connected, the active and the reactive power absorbed are calculated as a function of voltage as opposed to a regular consumer busbar. The algorithms for the two methods are presented. Finally, a numerical study for a test network is realized and the convergence is analyzed.
Calculation of degenerated Eigenmodes with modified power method
Energy Technology Data Exchange (ETDEWEB)
Zhang, Peng; Lee, Hyun Suk; Lee, Deok Jung [School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)
2017-02-15
The modified power method has been studied by many researchers to calculate the higher Eigenmodes and accelerate the convergence of the fundamental mode. Its application to multidimensional problems may be unstable due to degenerated or near-degenerated Eigenmodes. Complex Eigenmode solutions are occasionally encountered in such cases, and the shapes of the corresponding eigenvectors may change during the simulation. These issues must be addressed for the successful implementation of the modified power method. Complex components are examined and an approximation method to eliminate the usage of the complex numbers is provided. A technique to fix the eigenvector shapes is also provided. The performance of the methods for dealing with those aforementioned problems is demonstrated with two dimensional one group and three dimensional one group homogeneous diffusion problems.
Calculation of research reactor RA power at uncontrolled reactivity changes
International Nuclear Information System (INIS)
Cupac, S.
1978-01-01
The safety analysis of research reactor RA involves also the calculation of reactor power at uncontrolled reactivity changes. The corresponding computer code, based on Point Kinetics Model has been made. The short review of method applied for solving kinetic equations is given and several examples illustrating the reactor behaviour at various reactivity changes are presented. The results already obtained are giving rather rough picture of reactor behaviour in considered situations. This is the consequence of using simplified feed back and reactor cooling models, as well as temperature reactivity coefficients, which do not correspond to the actual reactor RA structure (which is now only partly fulfilled with 80% enriched uranium fuel). (author) [sr
Design and structural calculation of nuclear power plant mechanical components
International Nuclear Information System (INIS)
Amaral, J.A.R. do
1986-01-01
The mechanical components of a nuclear power plant must show high quality and safety due to the presence of radioactivity. Besides the perfect functioning during the rigid operating conditions, some postulated loadings are foreseen, like earthquake and loss of coolant accidents, which must be also considered in the design. In this paper, it is intended to describe the design and structural calculations concept and development, the interactions with the piping and civil designs, as well as their influences in the licensing process with the authorities. (Author) [pt
Investigating power factor compensation capacity calculation in medium sized industry
International Nuclear Information System (INIS)
Chudhry, M.A.; Hanif, A.
2008-01-01
There are a variety of techniques developed in order to improve the efficiency of electrical systems and reduce cost of providing electricity to the consumer. This paper presents a new technique for power-factor capacity calculation in medium-sized industrial/ commercial setups. Various loads of similar nominal power-factor are categorized and demand-factor of loads is so selected that it has engineering justifications. The developed system works on the principle of low-voltage power-factor correction, which substantially reduces electricity bill and increases loading-capacity of the electrical system. It allows commercial and industrial consumers to save on their power cost appreciably. This work utilizes software, which takes few inputs and produces numerous useful results. Adoption of this system can help the user in computing compensation-capacity, system KVA (size of transformer) and cost of compensation. A feature of this system is prediction of low PF penalty. Moreover, it also suggests the tentative payback period. (author)
Dynamic stability calculations for power grids employing a parallel computer
Energy Technology Data Exchange (ETDEWEB)
Schmidt, K
1982-06-01
The aim of dynamic contingency calculations in power systems is to estimate the effects of assumed disturbances, such as loss of generation. Due to the large dimensions of the problem these simulations require considerable computing time and costs, to the effect that they are at present only used in a planning state but not for routine checks in power control stations. In view of the homogeneity of the problem, where a multitude of equal generator models, having different parameters, are to be integrated simultaneously, the use of a parallel computer looks very attractive. The results of this study employing a prototype parallel computer (SMS 201) are presented. It consists of up to 128 equal microcomputers bus-connected to a control computer. Each of the modules is programmed to simulate a node of the power grid. Generators with their associated control are represented by models of 13 states each. Passive nodes are complemented by 'phantom'-generators, so that the whole power grid is homogenous, thus removing the need for load-flow-iterations. Programming of microcomputers is essentially performed in FORTRAN.
International Nuclear Information System (INIS)
Bettes, R.S.
1984-01-01
The paper discusses the real time performance calculations for the turbine cycle and reactor and steam generators of a nuclear power plant. Program accepts plant measurements and calculates performance and efficiency of each part of the cycle: reactor and steam generators, turbines, feedwater heaters, condenser, circulating water system, feed pump turbines, cooling towers. Presently, the calculations involve: 500 inputs, 2400 separate calculations, 500 steam properties subroutine calls, 200 support function accesses, 1500 output valves. The program operates in a real time system at regular intervals
Jarade, Elias F; Abi Nader, Françoise C; Tabbara, Khalid F
2006-01-01
To determine the new corneal effective index of refraction (rN) following LASIK to be used for accurate keratometry reading (K-reading). A total of 332 eyes that underwent myopic LASIK were divided into two groups (group A [n = 137] and group B [n = 1951). In each group, patients were divided into four subgroups according to the amount of spherical equivalent refraction of myopic LASIK ablation (subgroup 1 [ -12.0 D]). In each subgroup of group A, K-reading was measured by the clinical history method and the new corneal effective index (rN) was determined using paraxial formula: (K-reading = (rN-1)/Ra), where Ra is the radius of curvature of the anterior corneal surface. In group B, the anterior radius of curvature of the cornea was determined by automated K-reading, and K-reading was measured in each subgroup using the new effective index in paraxial formula, clinical history method, and automated K-reading. In group A, the new effective index of refraction was 1.3355, 1.3286, 1.3237, and 1.3172 in the four subgroups, respectively. In group B, the mean K-reading measurements using rN in paraxial formula, clinical history method, and automated K-reading were: 40.33 +/- 1.68 D, 40.33 +/- 1.67 D, and 40.54 +/- 1.69 D, respectively, in subgroup 1; 37.96 +/- 1.26 D, 38.03 +/- 1.38 D, and 38.98 +/- 1.28 D, respectively, in subgroup 2; 35.77 +/- 1.75 D, 35.84 +/- 1.85 D, and 37.29 +/- 1.83 D, respectively, in subgroup 3; and 34.03 +/- 1.49 D, 34.15 +/- 1.84 D, and 36.21 +/- 1.59 D, respectively, in subgroup 4. In all subgroups of group B, the results of K-reading obtained using the new effective index of refraction were statistically similar to the results obtained by clinical history method (P > .05). Automated K-reading statistically overestimated the K-reading values in subgroups 2, 3, and 4 of group B (P < .001). The use of the new corneal effective index of refraction allows for an accurate derivation of K-reading from the anterior radius of curvature.
International Nuclear Information System (INIS)
Even, J; Loualiche, S
2003-01-01
The problem of the energy levels and electronic wavefunctions in quantum dots is studied in the parabolic coordinates system. A conventional effective mass Hamiltonian is written. For an infinite potential barrier, it is related to the more general problem of finding the resonance modes in a cavity. The problem is found to be separable for a biconvex-shaped cavity or quantum dot with an infinite potential barrier. This first shape of quantum dot corresponds to the intersection of two orthogonal confocal parabolas. Then plano-convex lens-shaped cavities or quantum dots are studied. This problem is no more separable in the parabolic coordinates but using symmetry properties, we show that the exact solutions of the problem are simple combinations of the previous solutions. The same approach is used for spherical coordinates and hemispherical quantum dots. It is finally shown that convex lens-shaped quantum dots give a good description of self-organized InAs quantum dots grown on InP
A virtual power plant model for time-driven power flow calculations
Directory of Open Access Journals (Sweden)
Gerardo Guerra
2017-11-01
Full Text Available This paper presents the implementation of a custom-made virtual power plant model in OpenDSS. The goal is to develop a model adequate for time-driven power flow calculations in distribution systems. The virtual power plant is modeled as the aggregation of renewable generation and energy storage connected to the distribution system through an inverter. The implemented operation mode allows the virtual power plant to act as a single dispatchable generation unit. The case studies presented in the paper demonstrate that the model behaves according to the specified control algorithm and show how it can be incorporated into the solution scheme of a general parallel genetic algorithm in order to obtain the optimal day-ahead dispatch. Simulation results exhibit a clear benefit from the deployment of a virtual power plant when compared to distributed generation based only on renewable intermittent generation.
International Nuclear Information System (INIS)
Garcia, A.E.; Parkansky, D.G.
1993-01-01
In the Embalse nuclear power plant (CNE), the Regional Overpower Protection System acting on the Shutdown Systems number 1 and number 2 protects the reactor against overpowers in the reactor field for a localized peaking or a power increase in the reactor as a whole. This report summarizes the results of the critical channel power calculation for the time average powers configuration for the 380 reactor field channels. The final purpose of this work is to analyze and eventually modify the detector set points. Other reactor configurations are being analyzed. The report also presents a sensitivity analysis in order to evaluate potential sources of error and uncertainties which could affect the ROP performance. (author)
On-line calculation of 3-D power distribution
International Nuclear Information System (INIS)
Park, Y. H.; In, W. K.; Park, J. R.; Lee, C. C.; Auh, G. S.
1996-01-01
The 3-D power distribution synthesis scheme was implemented in Totally Integrated Core Operation Monitoring System (TICOMS), which is under development as the next generation core monitoring system. The on-line 3-D core power distribution obtained from the measured fixed incore detector readings is used to construct the hot pin power as well as the core average axial power distribution. The core average axial power distribution and the hot pin power of TICOMS were compared with those of the current digital on-line core monitoring system, COLSS, which construct the core average axial power distribution and the pseudo hot pin power. The comparison shows that TICOMS results in the slightly more accurate core average axial power distribution and the less conservative hot pin power. Therefore, these results increased the core operating margins. In addition, the on-line 3-D power distribution is expected to be very useful for the core operation in the future
Dong, Jing; Zhang, Yaqin; Zhang, Haining; Jia, Zhijie; Zhang, Suhua; Wang, Xiaogang
2018-01-01
To compare the axial length (AL), anterior chamber depth (ACD) and intraocular lens power (IOLP) of IOLMaster and Ultrasound in normal, long and short eyes. Seventy-four normal eyes (≥ 22 mm and ≤ 25 mm), 74 long eyes (> 25 mm) and 78 short eyes (devices in the order of IOLMaster followed by Ultrasound. The IOLP were calculated using a free online LADAS IOL formula calculator. The difference in AL and IOLP between IOLMaster and Ultrasound was statistically significant when all three groups were combined. The difference in ACD between IOLMaster and Ultrasound was statistically significant in the normal group (Peye group (Peye group (P = 0.465). For the IOLP difference between IOLMaster and Ultrasound in the normal group, the percentage of IOLP differences eye group, they were 90.5%, 5.4%, 4.1% and 0%, respectively. For the short eye group, they were 61.5%, 23.1%, 10.3%, and 5.1%, respectively. IOLMaster and Ultrasound have statistically significant differences in AL measurements and IOLP (using LADAS formula) for normal, long eye and short eye. The two instruments agree regarding ACD measurements for the long eye group, but differ for the normal and short eye groups. Moreover, the high percentage of IOLP differences greater than |0.5|D in the short eye group is noteworthy.
Calculated power output from a thin iron-seeded plasma
International Nuclear Information System (INIS)
Merts, A.L.; Cowan, R.D.; Magee, N.H. Jr.
1976-02-01
Ionization equilibrium calculations are carried out for iron ions at a density of 10 12 cm -3 in a (hydrogen) plasma with electron density 10 14 cm -3 , at temperatures from 0.8 to 10 keV. The computed radiated power loss from this plasma due to the iron ions ranges from about 4 W/cm 3 at the lowest temperature to about 0.4 W/cm 3 at the highest temperature; loss rates for other electron and ion densities will scale approximately as N/sub e/N/sub Fe/10 26 . The losses are due principally to collisionally excited line radiation (especially Δn = 0 transitions) at low temperatures, and to collisionally excited Δn not equal to 0 transitions and to continuum radiative recombination at high temperatures. Spectra are also computed for diagnostic x-ray K/sub α/ (1s - 2p) transitions; the change in spectral distribution as a function of temperature agrees well with observations in the ST Tokamak. Bound-bound radiative transitions and dielectronic recombination are discussed at length in appendices; the latter process is of great importance in the establishment of ionization equilibrium, and in the excitation of K/sub α/ radiation at the lower temperatures
Radiological shielding of low power compact reactor: calculation and design
International Nuclear Information System (INIS)
Marino, Raul
2004-01-01
The development of compact reactors becoming a technology that offers great projection and innumerable use possibilities, both in electricity generation and in propulsion.One of the requirements for the operation of this type of reactor is that it must include a radiological shield that will allow for different types of configurations and that, may be moved with the reactor if it needs to be transported.The nucleus of a reactor emits radiation, mainly neutrons and gamma rays in the heat of power, and gamma radiation during the radioactive decay of fission products.This radiation must be restrained in both conditions of operation to avoid it affecting workers or the public.The combination of different materials and properties in layers results in better performance in the form of a decrease in radiation, hence causing the dosage outside the reactor, whether in operation or shut down, to fall within the allowed limits.The calculations and design of radiological shields is therefore of paramount importance in reactor design.The choice of material and the design of the shield have a strong impact on the cost and the load capacity, the latter being one of the characteristics to optimize.The imposed condition of design is that the reactor can be transported together with the decay shield in a standard container of 40 foot [es
International Nuclear Information System (INIS)
Van Tilburg, X.; De Vries, H.J.; Pfeiffer, A.E.; Cleijne, J.W.
2005-09-01
The Ministry of Economic Affairs has requested ECN and KEMA to answer two questions. (1) Are the costs and benefits of projects in which wood-pellets are co-fired in a coal fired power plant representative for those of bio-oil fueled co-firing projects in a gas fired plant?; and (2) Are new projects representative for existing projects? To answer these questions, ECN and KEMA have calculated the financial gaps in six different situations: co-firing bio-oil in a gas fired power plant; co-firing bio-oil in a coal fired power plant; gasification of solid biomass; co-firing wood pellets in a coal fired power plant; co-firing agricultural residues in a coal fired power plant; and co-firing waste wood (A- and B-grade) in a coal fired power plant. The ranges and reference cases show that co-firing bio-oil on average has a smaller financial gap than the solid biomass reference case. On average it can also be concluded that when using waste wood or agro-residues, the financial gaps are smaller. Based on these findings it is concluded that: (1) The reference case of co-firing wood pellets in a coal fired power plant are not representative for bio-fuel options. A new category for bio-oil options seems appropriate; and (2) The financial gap of new projects as calculated in November 2004, is often higher then the ranges for existing projects indicate [nl
Input of biomass in power plants or the power generation. Calculation of the financial gap
International Nuclear Information System (INIS)
De Vries, H.J.; Van Tilburg, X.; Pfeiffer, A.E.; Cleijne, H.
2005-09-01
The project on the title subject concerns two questions: (1) Are projects in which wood-pellets are co-fired in a coalfired power plant representative for bio-oil fueled co-firing projects in a gas-fired plant?; and (2) are new projects representative for existing projects? To answer those questions the financial gaps have been calculated for five different situations: Co-firing bio-oil in a gas-fired power plant; Co-firing bio-oil in a coal-fired power plant; Co-firing wood pellets in a coal-fired power plant; Co-firing agro-residues in a coal-fired power plant; and Co-firing waste-wood (A- and B-grade) in a coal-fired power plant. The ranges and reference cases in this report show that co-firing bio-oil on average has a smaller financial gap than the solid biomass reference case. On average it can also be concluded that by using waste wood or agro-residues, the financial gaps can decrease [nl
Klee, H. W.; McDowell, M. W.
1986-02-01
A new lens design concept, based on the use of a zero (or near zero) power corrector, will be described. The logical development of the design, based on the work of Schmidt', Houghton' and others will be discussed and examples will be given of moderate field of view lenses with apertures ranging from f/0.35 to f/2. It will also be shown that the lens configuration is relatively insensitive to the aperture stop location and that for less demanding applications only very basic optical glass types need be used.
Editorial: Big data through the power lens: Marker for regulating innovation
Ulbricht, Lena; von Grafenstein, Maximilian
2016-01-01
Facing general conceptions of the power effects of big data, this thematic edition is interested in studies that scrutinise big data and power in concrete fields of application. It brings together scholars from different disciplines who analyse the fields agriculture, education, border control and consumer policy. As will be made explicit in the following, each of the articles tells us something about firstly, what big data is and how it relates to power. They secondly also shed light on how ...
Power plant reliability calculation with Markov chain models
International Nuclear Information System (INIS)
Senegacnik, A.; Tuma, M.
1998-01-01
In the paper power plant operation is modelled using continuous time Markov chains with discrete state space. The model is used to compute the power plant reliability and the importance and influence of individual states, as well as the transition probabilities between states. For comparison the model is fitted to data for coal and nuclear power plants recorded over several years. (orig.) [de
Yin, Qiwei; Lu, Huadong; Su, Jing; Peng, Kunchi
2016-05-01
The thermal lens effect of terbium gallium garnet (TGG) crystal in a high power single-frequency laser severely limits the output power and the beam quality of the laser. By inserting a potassium dideuterium phosphate (DKDP) slice with negative thermo-optical coefficient into the laser resonator, the harmful influence of the thermal lens effect of the TGG crystal can be effectively mitigated. Using this method, the stable range of the laser is broadened, the bistability phenomenon of the laser during the process of changing the pump power is completely eliminated, the highest output power of an all-solid-state continuous-wave intracavity-frequency-doubling single-frequency laser at 532 nm is enhanced to 30.2 W, and the beam quality of the laser is significantly improved.
Yang, Shan; Tong, Xiangqian
2016-01-01
Power flow calculation and short circuit calculation are the basis of theoretical research for distribution network with inverter based distributed generation. The similarity of equivalent model for inverter based distributed generation during normal and fault conditions of distribution network and the differences between power flow and short circuit calculation are analyzed in this paper. Then an integrated power flow and short circuit calculation method for distribution network with inverte...
Wind power limit calculation basedon frequency deviation using Matlab
International Nuclear Information System (INIS)
Santos Fuentefria, Ariel; Salgado Duarte, Yorlandis; MejutoFarray, Davis
2017-01-01
The utilization of the wind energy for the production of electricity it’s a technology that has promoted itself in the last years, like an alternative before the environmental deterioration and the scarcity of the fossil fuels. When the power generation of wind energy is integrated into the electrical power systems, maybe take place problems in the frequency stability due to, mainly, the stochastic characteristic of the wind and the impossibility of the wind power control on behalf of the dispatchers. In this work, is make an analysis of frequency deviation when the wind power generation rise in an isolated electrical power system. This analysis develops in a computerized frame with the construction of an algorithm using Matlab, which allowed to make several simulations in order to obtain the frequency behavior for different loads and wind power conditions. Besides, it was determined the wind power limit for minimum, medium and maximum load. The results show that the greatest values on wind power are obtained in maximum load condition. However, the minimum load condition limit the introduction of wind power into the system. (author)
Energy Technology Data Exchange (ETDEWEB)
Zhang, Yonghui; Wei, Tongbo, E-mail: tbwei@semi.ac.cn; Xiong, Zhuo; Shang, Liang; Tian, Yingdong; Zhao, Yun; Zhou, Pengyu; Wang, Junxi; Li, Jinmin [Semiconductor Lighting Technology Research and Development Center, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)
2014-07-07
The light-emitting diodes (LEDs) with single, twin, triple, and quadruple photonic crystals (PCs) on p-GaN are fabricated by multiple-exposure nanosphere-lens lithography (MENLL) process utilizing the focusing behavior of polystyrene spheres. Such a technique is easy and economical for use in fabricating compound nano-patterns. The optimized tilted angle is decided to be 26.6° through mathematic calculation to try to avoid the overlay of patterns. The results of scanning electron microscopy and simulations reveal that the pattern produced by MENLL is a combination of multiple ovals. Compared to planar-LED, the light output power of LEDs with single, twin, triple, and quadruple PCs is increased by 14.78%, 36.03%, 53.68%, and 44.85% under a drive current 350 mA, respectively. Furthermore, all PC-structures result in no degradation of the electrical properties. The stimulated results indicate that the highest light extraction efficiency of LED with the clover-shape triple PC is due to the largest scattering effect on propagation of light from GaN into air.
Hybrid Electric Vehicle Control Strategy Based on Power Loss Calculations
Boyd, Steven J
2006-01-01
Defining an operation strategy for a Split Parallel Architecture (SPA) Hybrid Electric Vehicle (HEV) is accomplished through calculating powertrain component losses. The results of these calculations define how the vehicle can decrease fuel consumption while maintaining low vehicle emissions. For a HEV, simply operating the vehicle's engine in its regions of high efficiency does not guarantee the most efficient vehicle operation. The results presented are meant only to define a literal str...
A simple approach to calculate active power of electrosurgical units
Directory of Open Access Journals (Sweden)
André Luiz Regis Monteiro
Full Text Available Abstract Introduction: Despite of more than a hundred years of electrosurgery, only a few electrosurgical equipment manufacturers have developed methods to regulate the active power delivered to the patient, usually around an arbitrary setpoint. In fact, no manufacturer has a method to measure the active power actually delivered to the load. Measuring the delivered power and computing it fast enough so as to avoid injury to the organic tissue is challenging. If voltage and current signals can be sampled in time and discretized in the frequency domain, a simple and very fast multiplication process can be used to determine the active power. Methods This paper presents an approach for measuring active power at the output power stage of electrosurgical units with mathematical shortcuts based on a simple multiplication procedure of discretized variables – frequency domain vectors – obtained through Discrete Fourier Transform (DFT applied on time-sampled voltage and current vectors. Results Comparative results between simulations and a practical experiment are presented – all being in accordance with the requirements of the applicable industry standards. Conclusion An analysis is presented comparing the active power analytically obtained through well-known voltage and current signals against a computational methodology based on vector manipulation using DFT only for time-to-frequency domain transformation. The greatest advantage of this method is to determine the active power of noisy and phased out signals with neither complex DFT or ordinary transform methodologies nor sophisticated computing techniques such as convolution. All results presented errors substantially lower than the thresholds defined by the applicable standards.
McDowell, M. W.; Klee, H. W.
1986-02-01
The use of the zero power corrector concept has been extended to the design of objective lenses and magnifiers suitable for use in night vision goggles. A novel design which can be used as either an f/1.2 objective or an f/2 magnifier is also described.
The Power of Symbolic Play in Emotional Development through the DIR Lens
Wieder, Serena
2017-01-01
Symbolic play is a powerful vehicle for supporting emotional development and communication. It embraces all developmental capacities. This article describes how symbols are formed and how emotional themes are symbolized whereby children reveal their understanding of the world, their feelings and relationships, and how they see themselves in the…
Calculation of the Magnetic Fields of the Electric Power Line
Directory of Open Access Journals (Sweden)
Patsiuk V.
2016-12-01
Full Text Available The task of calculation of per unit length parameters of multi-conductor electrical overhead transmission lines has been treated in the paper. The calculation of distribution of electric and magnetic fields has been performed by means of the finite volume method for entire span of the line. The theoretical justification of the method for calculation the parameters of electromagnetic field taking into account the change of the vector of magnetic potential along the line has been given. The problems of electrostatic and magnetostatic for a single electric conductor and unlimited long conductor with current have been solved. For the inner and total inductivities of a single conductor under the current have been obtained relationships and drawn dependences. Dependence between the speeds of light and of electromagnetic wave’s propagation has been presented. Based on the characteristics of distribution of electric and magnetic fields of multi-conductor lines has been provided the method of calculation of the matrix of own and mutual capacitances and inductivities the calculated values of per unit length parameters of compact 110 kV electric line which is in concordance with one of basic physical constant – the speed of light.
A New Power Calculation Method for Single-Phase Grid-Connected Systems
DEFF Research Database (Denmark)
Yang, Yongheng; Blaabjerg, Frede
2013-01-01
A new method to calculate average active power and reactive power for single-phase systems is proposed in this paper. It can be used in different applications where the output active power and reactive power need to be calculated accurately and fast. For example, a grid-connected photovoltaic...... system in low voltage ride through operation mode requires a power feedback for the power control loop. Commonly, a Discrete Fourier Transform (DFT) based power calculation method can be adopted in such systems. However, the DFT method introduces at least a one-cycle time delay. The new power calculation...... method, which is based on the adaptive filtering technique, can achieve a faster response. The performance of the proposed method is verified by experiments and demonstrated in a 1 kW single-phase grid-connected system operating under different conditions.Experimental results show the effectiveness...
Performance calculations for battery power supplies as laboratory research tools
International Nuclear Information System (INIS)
Scanlon, J.J.; Rolader, G.E.; Jamison, K.A.; Petresky, H.
1991-01-01
Electromagnetic Launcher (EML) research at the Air Force Armament Laboratory, Hypervelocity Launcher Branch (AFATL/SAH), Eglin AFB, has focused on developing the technologies required for repetitively launching several kilogram payloads to high velocities. Previous AFATL/SAH experiments have been limited by the available power supply resulting in small muzzle energies on the order of 100's of kJ. In an effort to advance the development of EML's, AFATL/SAH has designed and constructed a battery power supply (BPS) capable of providing several mega-Amperes of current for several seconds. This system consists of six modules each containing 2288 automotive batteries which may be connected in two different series - parallel arrangements. In this paper the authors define the electrical characteristics of the AFATL Battery Power supply at the component level
Power and Particle Balance Calculations with Impurities in NSTX
Holland, C. G.; Maingi, R.; Owen, L. W.; Kaye, S. M.
1998-11-01
We reported the development C. Holland, et. al., Bull. Am. Phys. Soc. 42 (1997) 1927. and application R. Maingi et al., Proc. 3rd International Workshop on Spherical Tori, Sept. 3-5, 1997, St. Petersburg, Russia. of a Graphical User Interface to assess the important terms for edge and divertor plasma calculations for NSTX with the b2.5 edge plasma transport code B. Braams, Contrib. Plasma Phys. 36 (1996) 276.. The goals of those calculations were to estimate the worst case peak heat flux for plasma-facing component design, and the radiation requirements to reduce the peak heat flux. In this study we present the first simulations with intrinsic carbon impurity radiation. We find in general that the intrinsic carbon radiation should be sufficient to provide a wide operation window for the NSTX device. Details of the relative importance of heat flux transport mechanisms as determined with the GUI will be presented.
The power series method in the effectiveness factor calculations
Filipich, C. P.; Villa, L. T.; Grossi, Ricardo Oscar
2017-01-01
In the present paper, exact analytical solutions are obtained for nonlinear ordinary differential equations which appear in complex diffusionreaction processes. A technique based on the power series method is used. Numerical results were computed for a number of cases which correspond to boundary value problems available in the literature. Additionally, new numerical results were generated for several important cases. Fil: Filipich, C. P.. Universidad Tecnológica Nacional. Facultad Regiona...
A lazy way to design infrared lens
Qiu, RongSheng; Wu, JianDong; Chen, LongJiang; Yu, Kun; Pang, HaoJun; Hu, BaiZhen
2017-08-01
We designed a compact middle-wave infrared (MWIR) lens with a large focal length ratio (about 1.5:1), used in the 3.7 to 4.8 μm range. The lens is consisted of a compact front group and a re-imaging group. Thanks to the compact front group configuration, it is possible to install a filter wheel mechanism in such a tight space. The total track length of the lens is about 50mm, which includes a 2mm thick protective window and a cold shield of 12mm. The full field of view of the lens is about 3.6°, and F number is less than 1.6, the image circle is about 4.6mm in diameter. The design performance of the lens reaches diffraction limitation, and doesn't change a lot during a temperature range of -40°C +60°C. This essay proposed a stepwise design method of infrared optical system guided by the qualitative approach. The method fully utilize the powerful global optimization ability, with a little effort to write code snippet in optical design software, frees optical engineer from tedious calculation of the original structure.
Comparison of different methods of calculating pinwise power
International Nuclear Information System (INIS)
Powers, M.A.
1987-01-01
One objective of a nuclear utility is the capability to predict the peak rod power in reload core design accurately and efficiently. This capability can be utilized in the verification of vendor results and the development of utility reload methodology. The MBS code solves the diffusion equation in x-y geometry by the finite different technique. The MBS code utilizes coarser meshes but reaches the same level of accuracy as a pin-by-pin model. The CASMO code utilizes pin profiles at specified core conditions, which are superimposed on the MBS diffusion theory results for pin power predictions. Placement of the burnable poison rods in the loading pattern are crucial to minimizing peak pin power. Westinghouse utilizes a code called TURTLE, licensed by the US Nuclear Regulatory Commission and proprietary to Westinghouse. The MBS code, with macroscopic cross sections from CASMO, can be run with coarser meshes and macroscopic depletion and still reach the same level of accuracy as a pin-by-pin code such as PDQ-7 or TURTLE. The MBS input preparation is simpler than PDQ-7 or TURTLE-type input preparation
Environment-based pin-power reconstruction method for homogeneous core calculations
International Nuclear Information System (INIS)
Leroyer, H.; Brosselard, C.; Girardi, E.
2012-01-01
Core calculation schemes are usually based on a classical two-step approach associated with assembly and core calculations. During the first step, infinite lattice assemblies calculations relying on a fundamental mode approach are used to generate cross-sections libraries for PWRs core calculations. This fundamental mode hypothesis may be questioned when dealing with loading patterns involving several types of assemblies (UOX, MOX), burnable poisons, control rods and burn-up gradients. This paper proposes a calculation method able to take into account the heterogeneous environment of the assemblies when using homogeneous core calculations and an appropriate pin-power reconstruction. This methodology is applied to MOX assemblies, computed within an environment of UOX assemblies. The new environment-based pin-power reconstruction is then used on various clusters of 3x3 assemblies showing burn-up gradients and UOX/MOX interfaces, and compared to reference calculations performed with APOLLO-2. The results show that UOX/MOX interfaces are much better calculated with the environment-based calculation scheme when compared to the usual pin-power reconstruction method. The power peak is always better located and calculated with the environment-based pin-power reconstruction method on every cluster configuration studied. This study shows that taking into account the environment in transport calculations can significantly improve the pin-power reconstruction so far as it is consistent with the core loading pattern. (authors)
Vu, Lien T; Chen, Chao-Chang A; Lee, Chia-Cheng; Yu, Chia-Wei
2018-04-20
This study aims to develop a compensating method to minimize the shrinkage error of the shell mold (SM) in the injection molding (IM) process to obtain uniform optical power in the central optical zone of soft axial symmetric multifocal contact lenses (CL). The Z-shrinkage error along the Z axis or axial axis of the anterior SM corresponding to the anterior surface of a dry contact lens in the IM process can be minimized by optimizing IM process parameters and then by compensating for additional (Add) powers in the central zone of the original lens design. First, the shrinkage error is minimized by optimizing three levels of four IM parameters, including mold temperature, injection velocity, packing pressure, and cooling time in 18 IM simulations based on an orthogonal array L 18 (2 1 ×3 4 ). Then, based on the Z-shrinkage error from IM simulation, three new contact lens designs are obtained by increasing the Add power in the central zone of the original multifocal CL design to compensate for the optical power errors. Results obtained from IM process simulations and the optical simulations show that the new CL design with 0.1 D increasing in Add power has the closest shrinkage profile to the original anterior SM profile with percentage of reduction in absolute Z-shrinkage error of 55% and more uniform power in the central zone than in the other two cases. Moreover, actual experiments of IM of SM for casting soft multifocal CLs have been performed. The final product of wet CLs has been completed for the original design and the new design. Results of the optical performance have verified the improvement of the compensated design of CLs. The feasibility of this compensating method has been proven based on the measurement results of the produced soft multifocal CLs of the new design. Results of this study can be further applied to predict or compensate for the total optical power errors of the soft multifocal CLs.
Power calculations using exact data simulation: A useful tool for genetic study designs
van der Sluis, S.; Dolan, C.V.; Neale, M.C.; Posthuma, D.
2008-01-01
Statistical power calculations constitute an essential first step in the planning of scientific studies. If sufficient summary statistics are available, power calculations are in principle straightforward and computationally light. In designs, which comprise distinct groups (e.g., MZ & DZ twins),
Analytic models of plausible gravitational lens potentials
International Nuclear Information System (INIS)
Baltz, Edward A.; Marshall, Phil; Oguri, Masamune
2009-01-01
Gravitational lenses on galaxy scales are plausibly modelled as having ellipsoidal symmetry and a universal dark matter density profile, with a Sérsic profile to describe the distribution of baryonic matter. Predicting all lensing effects requires knowledge of the total lens potential: in this work we give analytic forms for that of the above hybrid model. Emphasising that complex lens potentials can be constructed from simpler components in linear combination, we provide a recipe for attaining elliptical symmetry in either projected mass or lens potential. We also provide analytic formulae for the lens potentials of Sérsic profiles for integer and half-integer index. We then present formulae describing the gravitational lensing effects due to smoothly-truncated universal density profiles in cold dark matter model. For our isolated haloes the density profile falls off as radius to the minus fifth or seventh power beyond the tidal radius, functional forms that allow all orders of lens potential derivatives to be calculated analytically, while ensuring a non-divergent total mass. We show how the observables predicted by this profile differ from that of the original infinite-mass NFW profile. Expressions for the gravitational flexion are highlighted. We show how decreasing the tidal radius allows stripped haloes to be modelled, providing a framework for a fuller investigation of dark matter substructure in galaxies and clusters. Finally we remark on the need for finite mass halo profiles when doing cosmological ray-tracing simulations, and the need for readily-calculable higher order derivatives of the lens potential when studying catastrophes in strong lenses
Olczak, Eugene G. (Inventor)
2011-01-01
An objective lens and a method for using same. The objective lens has a first end, a second end, and a plurality of optical elements. The optical elements are positioned between the first end and the second end and are at least substantially symmetric about a plane centered between the first end and the second end.
Nuclear power history calculation for subcritical systems using Euler-MacLaurin formula
International Nuclear Information System (INIS)
Henrice Junior, Edson; Goncalves, Alessandro da Cruz
2013-01-01
This paper presents an efficient method for calculating the reactivity using inverse point kinetic equation for subcritical systems by applying the Euler-MacLaurin summation formula to calculate the nuclear power history. In accordance with the accuracy of the numerical results, this method does not require a large number of points for calculation, providing accurate results with low computational cost. (author)
Power Loss Calculation and Thermal Modelling for a Three Phase Inverter Drive System
Directory of Open Access Journals (Sweden)
Z. Zhou
2005-12-01
Full Text Available Power losses calculation and thermal modelling for a three-phase inverter power system is presented in this paper. Aiming a long real time thermal simulation, an accurate average power losses calculation based on PWM reconstruction technique is proposed. For carrying out the thermal simulation, a compact thermal model for a three-phase inverter power module is built. The thermal interference of adjacent heat sources is analysed using 3D thermal simulation. The proposed model can provide accurate power losses with a large simulation time-step and suitable for a long real time thermal simulation for a three phase inverter drive system for hybrid vehicle applications.
Rieprich, J.; Winterfeldt, M.; Kernke, R.; Tomm, J. W.; Crump, P.
2018-03-01
High power broad area diode lasers with high optical power density in a small focus spot are in strong commercial demand. For this purpose, the beam quality, quantified via the beam parameter product (BPP), has to be improved. Previous studies have shown that the BPP is strongly affected by current-induced heating and the associated thermal lens formed within the laser stripe. However, the chip structure and module-assembly related factors that regulate the size and the shape of the thermal lens are not well known. An experimental infrared thermographic technique is used to quantify the thermal lens profile in diode lasers operating at an emission wavelength of 910 nm, and the results are compared with finite element method simulations. The analysis indicates that the measured thermal profiles can best be explained when a thermal barrier is introduced between the chip and the carrier, which is shown to have a substantial impact on the BPP and the thermal resistance. Comparable results are observed in further measurements of samples from multiple vendors, and the barrier is only observed for junction-down (p-down) mounting, consistent with the barrier being associated with the GaAs-metal transition.
Maceo, Bianca M; Manns, Fabrice; Borja, David; Nankivil, Derek; Uhlhorn, Stephen; Arrieta, Esdras; Ho, Arthur; Augusteyn, Robert C; Parel, Jean-Marie
2011-11-30
The purpose of this study was to determine the contribution of the gradient refractive index to the change in lens power in hamadryas baboon and cynomolgus monkey lenses during simulated accommodation in a lens stretcher. Thirty-six monkey lenses (1.4-14.1 years) and twenty-five baboon lenses (1.8-28.0 years) were stretched in discrete steps. At each stretching step, the lens back vertex power was measured and the lens cross-section was imaged with optical coherence tomography. The radii of curvature for the lens anterior and posterior surfaces were calculated for each step. The power of each lens surface was determined using refractive indices of 1.365 for the outer cortex and 1.336 for the aqueous. The gradient contribution was calculated by subtracting the power of the surfaces from the measured lens power. In all lenses, the contribution of the surfaces and gradient increased linearly with the amplitude of accommodation. The gradient contributes on average 65 ± 3% for monkeys and 66 ± 3% for baboons to the total power change during accommodation. When expressed in percent of the total power change, the relative contribution of the gradient remains constant with accommodation and age in both species. These findings are consistent with Gullstrand's intracapsular theory of accommodation.
Directory of Open Access Journals (Sweden)
Tae-Yong Park
2017-01-01
Full Text Available Cube satellites have a limitation for generating power because of their cubic structure and extremely small size. In addition, the incidence angle between the sun and the solar panels continuously varies owing to the revolution and rotation of the satellite according to the attitude control strategy. This angle is an important parameter for determining the power generation performance of the cube satellite. In this study, we performed an experimental feasibility study that uses a Fresnel lens as a solar-energy collection system for cube satellite applications, so that the power generation efficiency can be enhanced under the worst incidence angle condition between the sun and solar panels by concentrating and redirecting solar energy onto the solar panels with a commercial Fresnel lens. To verify the effectiveness of the proposed system, we conducted a power-measurement test using a solar simulator and Fresnel lenses at various angles to the light source. In addition, we predicted the on-orbit power-generation enhancement achieved by employing the solar-energy collection system with various attitude control strategies.
Audit Calculations of LBLOCA for Ulchin Unit 1 and 2 Power Up rate
Energy Technology Data Exchange (ETDEWEB)
Kang, Donggu; Huh, Byunggil; Yoo, Seunghunl; Yang, Chaeyong; Seul, Kwangwon [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)
2013-05-15
The KINS-Realistic Evaluation Model (KINS-REM) was developed for the independent audit calculation in 1991, and the code accuracy and statistical method have been improved. To support the licensing review and to confirm the validity of licensee's calculation, regulatory auditing calculations have been also conducted. Currently, the modification of Ulchin 1 and 2 operating license for 4.5% power up rate is under review. In this study, the regulatory audit calculation for LBLOCA of Ulchin Unit 1 and 2 with 4.5% power up rate was performed by applying KINS-REM. In this study, the regulatory audit calculation for LBLOCA of Ulchin Unit 1 and 2 with 4.5% power up rate was performed by applying KINS-REM. It is confirmed that the analysis results of LBLOCA for Ulchin 1 and 2 power up rate meets the PCT acceptance criteria.
Typical calculation and analysis of carbon emissions in thermal power plants
Gai, Zhi-jie; Zhao, Jian-gang; Zhang, Gang
2018-03-01
On December 19, 2017, the national development and reform commission issued the national carbon emissions trading market construction plan (power generation industry), which officially launched the construction process of the carbon emissions trading market. The plan promotes a phased advance in carbon market construction, taking the power industry with a large carbon footprint as a breakthrough, so it is extremely urgent for power generation plants to master their carbon emissions. Taking a coal power plant as an example, the paper introduces the calculation process of carbon emissions, and comes to the fuel activity level, fuel emissions factor and carbon emissions data of the power plant. Power plants can master their carbon emissions according to this paper, increase knowledge in the field of carbon reserves, and make the plant be familiar with calculation method based on the power industry carbon emissions data, which can help power plants positioning accurately in the upcoming carbon emissions trading market.
Ogbuehi, Kelechi C
2012-06-01
To quantify the influence of soft contact lens power and thickness on the intraocular pressure (IOP). Thirty-nine young, healthy adult volunteers completed this study. One eye of each subject was randomly assigned either a +6D or a -6D high water content daily disposable lens. The other eye was fitted with the second lens. Triplicate measurements of IOP were taken before, during, and after contact lens wear. Each time, IOP was assessed in a randomized order with two noncontact tonometers. The lenses were swapped between eyes during a second session of measurements, one week later. In the first session with the +6D lenses, the average IOPs (±SDs) before, with the lenses fitted, and after the lenses were removed, were: 14.3 ± 2.9 mmHg, 17.0 ± 3.3 mmHg and 13.9 ± 3.1 mmHg, respectively, for the CT80 and 13.6 ± 3.1 mmHg, 17.1 ± 4.5 mmHg and 13.3 ± 2.9 mmHg, respectively, for the PT100. The corresponding values for the first session with the -6D lenses were: 14.3 ± 3.1 mmHg, 13.1 ± 3.1 mmHg and 14.1 ± 3.3 mmHg, respectively, for the CT80 and 13.6 ± 3.2 mmHg, 13.0 ± 3.0 mmHg and 13.6 ± 3.2 mmHg, respectively, for the PT100. IOP significantly (Psoft contact lens-induced changes were consistent between sessions but varied between tonometers. The measurement of IOP through soft contact lenses resulted in consistent, statistically significant differences in IOP, which were not uniform across tonometers and which did not appear to be solely related to the central thickness of the soft contact lenses. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
DISSECTING THE GRAVITATIONAL LENS B1608+656. I. LENS POTENTIAL RECONSTRUCTION
Suyu, S. H.; Marshall, P. J.; Blandford, R. D.; Fassnacht, C. D.; Koopmans, L. V. E.; McKean, J. P.; Treu, T.
2009-01-01
Strong gravitational lensing is a powerful technique for probing galaxy mass distributions and for measuring cosmological parameters. Lens systems with extended source-intensity distributions are particularly useful for this purpose since they provide additional constraints on the lens potential (
Active liquid-crystal deflector and lens with Fresnel structure
Shibuya, Giichi; Yamano, Shohei; Yoshida, Hiroyuki; Ozaki, Masanori
2017-02-01
A new type of tunable Fresnel deflector and lens composed of liquid crystal was developed. Combined structure of multiple interdigitated electrodes and the high-resistivity (HR) layer implements the saw-tooth distribution of electrical potential with only the planar surfaces of the transparent substrates. According to the numerical calculation and design, experimental devices were manufactured with the liquid crystal (LC) material sealed into the sandwiched flat glass plates of 0.7 mm thickness with rubbed alignment layers set to an anti-parallel configuration. Fabricated beam deflector with no moving parts shows the maximum tilt angle of +/-1.3 deg which can apply for optical image stabilizer (OIS) of micro camera. We also discussed and verified their lens characteristics to be extended more advanced applications. Transparent interdigitated electrodes were concentrically aligned on the lens aperture with the insulator gaps under their boundary area. The diameter of the lens aperture was 30 mm and the total number of Fresnel zone was 100. Phase retardation of the beam wavefront irradiated from the LC lens device can be evaluated by polarizing microscope images with a monochromatic filter. Radial positions of each observed fringe are plotted and fitted with 2nd degree polynomial approximation. The number of appeared fringes is over 600 in whole lens aperture area and the correlation coefficients of all approximations are over 0.993 that seems enough ideal optical wavefront. The obtained maximum lens powers from the approximations are about +/-4 m-1 which was satisfied both convex and concave lens characteristics; and their practical use for the tunable lens grade eyeglasses became more prospective.
Hydraulic simulation of the systems of a nuclear power plant for charges calculation in piping
International Nuclear Information System (INIS)
Masriera, N.
1990-01-01
This work presents a general description of the methodology used by the ENACE S.A. Fluids Working Group for hydraulics simulation of a nuclear power plant system for the calculation charges in piping. (Author) [es
Reactor theory and power reactors. 1. Calculational methods for reactors. 2. Reactor kinetics
International Nuclear Information System (INIS)
Henry, A.F.
1980-01-01
Various methods for calculation of neutron flux in power reactors are discussed. Some mathematical models used to describe transients in nuclear reactors and techniques for the reactor kinetics' relevant equations solution are also presented
Development of a power-period calculation unit for nuclear reactor Control
International Nuclear Information System (INIS)
Martin, J.
1966-10-01
The apparatus studied is a digital calculating assembly which makes it possible to prepare and to present numerically the period and power of a nuclear reactor during operation, from start-up to nominal power. The pulses from a fission chamber are analyzed continuously, using real time. A small number of elements is required because of the systematic use of a calculation technique comprising the determination of a base 2 logarithm by a linear approximation. The accuracy obtained for the period is of the order of 14%; the response time of the order of the calculated period value. An approximate value of the power (30%) is given at each calculation cycle together with the power thresholds required for the control. (author) [fr
On the nuclear shell effects appeared in (p,t) analyzing power calculations
International Nuclear Information System (INIS)
Kubo, Ken-ichi
1980-01-01
Origin of shell effects found in two-step (p, d, t) calculation, which play an important role for understanding the observed 'anomalous' (p, t) analyzing powers, is clarified based on the selections for transferred angular momenta. (author)
Lau, F.K.; Tee, C.W.; Zhao, Xin; Williams, K.A.; Penty, R.V.; White, I.H.; Calligaro, M.; Lecomte, M.; Parillaud, O.; Michel, N.; Krakowski, M.
2006-01-01
We demonstrate, for the first time, a monolithic integrated lens for wide aperture gain-guided tapered laser beam quality enhancement by compensating the quadratic phase curvature. The 3mm long tapered laser with an output aperture of 170µm adopted in this design consists of a gain-guided tapered
Sliding Window Technique for Calculating System LOLP Contributions of Wind Power Plants
International Nuclear Information System (INIS)
Milligan, M. R.
2001-01-01
Conventional electric power generation models do not typically recognize the probabilistic nature of the power variations from wind plants. Most models allow for an accurate hourly representation of wind power output, but do not incorporate any probabilistic assessment of whether the given level of wind power will vary from its expected value. The technique presented in this paper uses this variation to calculate an effective forced-outage rate for wind power plants (EFORW). Depending on the type of wind regime undergoing evaluation, the length and diurnal characteristics of a sliding time window can be adjusted so that the EFORW is based on an appropriate time scale. The algorithm allows us to calculate the loss-of-load probability (LOLP) on an hourly basis, fully incorporating the variability of the wind resource into the calculation. This makes it possible to obtain a more accurate assessment of reliability of systems that include wind generation when system reliability is a concern
"Cloud" functions and templates of engineering calculations for nuclear power plants
Ochkov, V. F.; Orlov, K. A.; Ko, Chzho Ko
2014-10-01
The article deals with an important problem of setting up computer-aided design calculations of various circuit configurations and power equipment carried out using the templates and standard computer programs available in the Internet. Information about the developed Internet-based technology for carrying out such calculations using the templates accessible in the Mathcad Prime software package is given. The technology is considered taking as an example the solution of two problems relating to the field of nuclear power engineering.
Feng, Sheng; Wang, Shengchu; Chen, Chia-Cheng; Lan, Lan
2011-01-21
In designing genome-wide association (GWA) studies it is important to calculate statistical power. General statistical power calculation procedures for quantitative measures often require information concerning summary statistics of distributions such as mean and variance. However, with genetic studies, the effect size of quantitative traits is traditionally expressed as heritability, a quantity defined as the amount of phenotypic variation in the population that can be ascribed to the genetic variants among individuals. Heritability is hard to transform into summary statistics. Therefore, general power calculation procedures cannot be used directly in GWA studies. The development of appropriate statistical methods and a user-friendly software package to address this problem would be welcomed. This paper presents GWAPower, a statistical software package of power calculation designed for GWA studies with quantitative traits, where genetic effect is defined as heritability. Based on several popular one-degree-of-freedom genetic models, this method avoids the need to specify the non-centrality parameter of the F-distribution under the alternative hypothesis. Therefore, it can use heritability information directly without approximation. In GWAPower, the power calculation can be easily adjusted for adding covariates and linkage disequilibrium information. An example is provided to illustrate GWAPower, followed by discussions. GWAPower is a user-friendly free software package for calculating statistical power based on heritability in GWA studies with quantitative traits. The software is freely available at: http://dl.dropbox.com/u/10502931/GWAPower.zip.
Directory of Open Access Journals (Sweden)
Shan Yang
2016-01-01
Full Text Available Power flow calculation and short circuit calculation are the basis of theoretical research for distribution network with inverter based distributed generation. The similarity of equivalent model for inverter based distributed generation during normal and fault conditions of distribution network and the differences between power flow and short circuit calculation are analyzed in this paper. Then an integrated power flow and short circuit calculation method for distribution network with inverter based distributed generation is proposed. The proposed method let the inverter based distributed generation be equivalent to Iθ bus, which makes it suitable to calculate the power flow of distribution network with a current limited inverter based distributed generation. And the low voltage ride through capability of inverter based distributed generation can be considered as well in this paper. Finally, some tests of power flow and short circuit current calculation are performed on a 33-bus distribution network. The calculated results from the proposed method in this paper are contrasted with those by the traditional method and the simulation method, whose results have verified the effectiveness of the integrated method suggested in this paper.
The calculation of proton and secondary electron stopping powers in liquid water
International Nuclear Information System (INIS)
Marouane, Abdelhak; Inchaouh, Jamal; Ouaskit, Said; Fathi, Ahmed
2012-01-01
The stopping power of energetic protons in liquid water has been calculated using a new model based on different theoretical and semi-empirical approaches. In this model, we consider the relativistic corrections along with the electronic and nuclear stopping power. The present work accounts for the different interactions made with electrons and nuclei inside the target. Interactions of the incident particle with the target's electrons dominate in the high energy regime; in the low energy regime, the interactions of the projectile with the target nuclei contribute importantly and are included in the calculation. We also compute the stopping cross sections and the stopping power of secondary electrons ejected from proton and hydrogen ionization impact, and generated by hydrogen electron loss processes. The consideration of secondary electrons' stopping power can contribute to the study of nano-dosimetry. Our results are in good agreement with existing experimental data. This calculation model can be useful for different applications in medical physics and space radiation health, such as hadron therapy for cancer treatment or radiation protection for astronauts. - Highlights: ► We discussed the stopping cross sections at the Bragg peak region of primary and secondary processes. ► We considered the corrections of incident particle energy focusing on the Rudds semi-empirical model. ► We calculated the electronic and nuclear stopping power, and we deduced the total stopping power. ► We calculated the stopping power of the secondary electrons.
An assessment of fission product data for decay power calculation in fast reactors
International Nuclear Information System (INIS)
Sridharan, M.S.; Murthy, K.P.N.
1987-01-01
A review of our present capability at IGC, Kalpakkam to predict fission product decay power in fast reactors is presented. This is accomplished by comparing our summation calculations with the calculations of others and the reported experimental measurements. Our calculations are based on Chandy code developed at our Centre. The fission product data base of Chandy is essentially drawn from the yield data compiled by Crouch (1977) and the data on halflives etc. compiled by Tobias (1973). In general, we find good agreement amongst the different calculations (within ±5%) and our calculations also compare well with experimental measurements of AKIAMA et al and MURPHY et al
Control of Solar Power Plants Connected Grid with Simple Calculation Method on Residential Homes
Kananda, Kiki; Nazir, Refdinal
2017-12-01
One of the most compatible renewable energy in all regions to apply is solar energy. Solar power plants can be built connected to existing or stand-alone power grids. In assisting the residential electricity in which there is a power grid, then a small scale solar energy power plants is very appropriate. However, the general constraint of solar energy power plants is still low in terms of efficiency. Therefore, this study will explain how to control the power of solar power plants more optimally, which is expected to reactive power to zero to raise efficiency. This is a continuation of previous research using Newton Rapshon control method. In this study we introduce a simple method by using ordinary mathematical calculations of solar-related equations. In this model, 10 PV modules type of ND T060M1 with a 60 Wp capacity are used. The calculations performed using MATLAB Simulink provide excellent value. For PCC voltage values obtained a stable quantity of approximately 220 V. At a maximum irradiation condition of 1000 W / m2, the reactive power value of Q solar generating system maximum 20.48 Var and maximum active power of 417.5 W. In the condition of lower irradiation, value of reactive power Q almost close to zero 0.77Var. This simple mathematical method can provide excellent quality control power values.
Influence of FRAPCON-1 evaluation models on fuel behavior calculations for commercial power reactors
International Nuclear Information System (INIS)
Chambers, R.; Laats, E.T.
1981-01-01
A preliminary set of nine evaluation models (EMs) was added to the FRAPCON-1 computer code, which is used to calculate fuel rod behavior in a nuclear reactor during steady-state operation. The intent was to provide an audit code to be used in the United States Nuclear Regulatory Commission (NRC) licensing activities when calculations of conservative fuel rod temperatures are required. The EMs place conservatisms on the calculation of rod temperature by modifying the calculation of rod power history, fuel and cladding behavior models, and materials properties correlations. Three of the nine EMs provide either input or model specifications, or set the reference temperature for stored energy calculations. The remaining six EMs were intended to add thermal conservatism through model changes. To determine the relative influence of these six EMs upon fuel behavior calculations for commercial power reactors, a sensitivity study was conducted. That study is the subject of this paper
Calculations on heavy-water moderated and cooled natural uranium fuelled power reactors
International Nuclear Information System (INIS)
Pinedo V, J.L.
1979-01-01
One of the codes that the Instituto Nacional de Investigaciones Nucleares (Mexico) has for the nuclear reactors design calculations is the LEOPARD code. This work studies the reliability of this code in reactors design calculations which component materials are the same of the heavy water moderated and cooled, natural uranium fuelled power reactors. (author)
A simple method for calculating power based on a prior trial.
Borm, G.F.; Bloem, B.R.; Munneke, M.; Teerenstra, S.
2010-01-01
OBJECTIVE: When an investigator wants to base the power of a planned clinical trial on the outcome of another trial, the latter study may not have been reported in sufficient detail to allow this. For example, when the outcome is a change from baseline, the power calculation requires the standard
To the calculation of reduced cost capital component for power objects
International Nuclear Information System (INIS)
Andryushchenko, A.I.; Larin, E.A.
1990-01-01
The method for calculating capitalized cost component enabling comparison of alternative arrangement variants of power plant, is suggested. It is shown that in order to realize the technical-economical estimates in power industry for determination of capitalized cost component it is necessary to take into account capital construction expenditures as well as deductions for the plant dismountling and elimination of potential accidents
Quantum-dot saturable absorber and Kerr-lens mode-locked Yb:KGW laser with >450 kW of peak power.
Akbari, R; Zhao, H; Fedorova, K A; Rafailov, E U; Major, A
2016-08-15
The hybrid action of quantum-dot saturable absorber and Kerr-lens mode locking in a diode-pumped Yb:KGW laser was demonstrated. Using a quantum-dot saturable absorber with a 0.7% (0.5%) modulation depth, the mode-locked laser delivered 90 fs (93 fs) pulses with 3.2 W (2.9 W) of average power at the repetition rate of 77 MHz, corresponding to 462 kW (406 kW) of peak power and 41 nJ (38 nJ) of pulse energy. To the best of our knowledge, this represents the highest average and peak powers generated to date from quantum-dot saturable absorber-based mode-locked lasers.
Axial power distribution calculation using a neural network in the nuclear reactor core
Energy Technology Data Exchange (ETDEWEB)
Kim, Y. H.; Cha, K. H.; Lee, S. H. [Korea Electric Power Research Institute, Taejon (Korea, Republic of)
1997-12-31
This paper is concerned with an algorithm based on neural networks to calculate the axial power distribution using excore detector signals in the nuclear reactor core. The fundamental basis of the algorithm is that the detector response can be fairly accurately estimated using computational codes. In other words, the training set, which represents relationship between detector signals and axial power distributions, for the neural network can be obtained through calculations instead of measurements. Application of the new method to the Yonggwang nuclear power plant unit 3 (YGN-3) shows that it is superior to the current algorithm in place. 7 refs., 4 figs. (Author)
Axial power distribution calculation using a neural network in the nuclear reactor core
Energy Technology Data Exchange (ETDEWEB)
Kim, Y H; Cha, K H; Lee, S H [Korea Electric Power Research Institute, Taejon (Korea, Republic of)
1998-12-31
This paper is concerned with an algorithm based on neural networks to calculate the axial power distribution using excore detector signals in the nuclear reactor core. The fundamental basis of the algorithm is that the detector response can be fairly accurately estimated using computational codes. In other words, the training set, which represents relationship between detector signals and axial power distributions, for the neural network can be obtained through calculations instead of measurements. Application of the new method to the Yonggwang nuclear power plant unit 3 (YGN-3) shows that it is superior to the current algorithm in place. 7 refs., 4 figs. (Author)
International Nuclear Information System (INIS)
Sanchez, F. A.; Blaumann, H.; Lopasso, E.; Longhino, J
2009-01-01
The maximum power of a reactor is limited by the power peaking factor. During the design stage it is calculated with neutronic calculation codes. This is not enough for ensuring its value due to modelling approximations. For the RA-6s low enrichment new core a calculus-measurement correlation method have been applied. Position and magnitude of the maximum power density estimated by calculus are used by this method. For this work 249 cooper-gold alloy (1.55% Au) wires have been distributed along the core using 19 aluminium blades. Their positions have been selected using information given by a 5 groups PUMA reactor model. Wire s activity have been measured with a HPGe detector. Gold activity have been used only for verifying the calculated core spectrum. The measured power peaking factor was 2.48±0.3 (3σ), 15% above the calculated value. About 97% of measured points had less than 20% calculation-measurement difference and about 80% had less than 10%. The power peaking factor determined by this method consolidates also the calculations models. [es
Wang, Yaping; Lin, Shunjiang; Yang, Zhibin
2017-05-01
In the traditional three-phase power flow calculation of the low voltage distribution network, the load model is described as constant power. Since this model cannot reflect the characteristics of actual loads, the result of the traditional calculation is always different from the actual situation. In this paper, the load model in which dynamic load represented by air conditioners parallel with static load represented by lighting loads is used to describe characteristics of residents load, and the three-phase power flow calculation model is proposed. The power flow calculation model includes the power balance equations of three-phase (A,B,C), the current balance equations of phase 0, and the torque balancing equations of induction motors in air conditioners. And then an alternating iterative algorithm of induction motor torque balance equations with each node balance equations is proposed to solve the three-phase power flow model. This method is applied to an actual low voltage distribution network of residents load, and by the calculation of three different operating states of air conditioners, the result demonstrates the effectiveness of the proposed model and the algorithm.
Quasi-mosaicity of (311) planes in silicon and its use in a Laue lens with high-focusing power
Camattari, Riccardo; Paternò, Gianfranco; Bellucci, Valerio; Guidi, Vincenzo
2014-12-01
(311) curved planes can be exploited for efficiently focus hard X-rays. With this purpose, a self-standing bent crystal was manufactured at the Sensor and Semiconductor Laboratory of Ferrara (Italy). The crystal was designed as an optical component for a X-ray concentrator such as a Laue lens. The curvature of (311) planes was obtained through the quasi-mosaic effect. The diffraction efficiency of the sample was tested at the Institut Laue Langevin of Grenoble (France) by using a collimated monochromatic X-ray beam. This was the first prove of the diffraction properties of (311) quasi-mosaic planes. Diffraction efficiency resulted 35 % with a 182 keV X-ray beam, in agreement with the theoretical expectation. It corresponded to a reflectivity of 33 %. While the chosen orientation is not the most performing lying of planes, it can be used, in addition to smaller-index planes, in order to raise the total effective area of a Laue lens. To quantify it, a Laue lens based on quasi-mosaic silicon and germanium crystals, exploiting (111), (422) and (311) diffracting planes, was achieved and simulated with the LaueGen code.
A calculation technique of passing of a powerful relativistic beam through substance
International Nuclear Information System (INIS)
Pobitko, A.I.; Sal'nikov, L.I.; Sukhovitskij, E.Sh.
1995-01-01
The calculation algorithm of passing powerful relativistic beam through substance is developed. Algorithm of calculation is separated on the following problems: 1) a trial charge movement in electromagnetic field of the cylindrical geometry; 2) a computing of own electromagnetic field arising at movement of a particle heavy-current beam in a target; 3) accounting of an interaction of a beam with target atoms; 4) accounting of change of the target properties in a time; 5) geometry and construction of an iterative procedure of calculation. The calculation of passing heavy-current beams of charged particles for transient case is carried out by Monte Carlo method. A conclusion of equations of movement trial charge and technique of calculation own electromagnetic field of the powerful relativistic beam at passing through substance are resulted. 6 refs
Institute of Scientific and Technical Information of China (English)
2012-01-01
The integrated power generation system of wind, photovoltaic （PV） and energy storage is composed of several wind turbines, PV units and energy storage units. The detailed model of integrated generation is not suitable for the large-scale powe.r system simulation because of the model＇s complexity and long computation time. An equivalent method for power flow calculation and transient simulation of the integrated generation system is proposed based on actual projects, so as to establish the foundation of such integrated system simulation and analysis.
A proposal of a benchmark for calculation of the power distribution next to the absorber
International Nuclear Information System (INIS)
Temesvari, E.; Hordosy, G.; Maraczy, Cs.; Hegyi, Gy.; Kereszturi, A.
1999-01-01
A proposal of a new benchmark problem was formulated to consider the characteristics of the VVER-440 fuel assembly with enrichment zoning, i. e. to study the space dependence of the power distribution near to a control assembly. A quite detailed geometry and the material composition of the fuel and the control assemblies were modeled by the help of MCNP calculations in AEKI. The results of the MCNP calculations were built in the KARATE code system as the new albedo matrices. The comparison of the KARATE calculation results and the MCNP calculations for this benchmark is presented. (Authors)
Power Consumption and Calculation Requirement Analysis of AES for WSN IoT.
Hung, Chung-Wen; Hsu, Wen-Ting
2018-05-23
Because of the ubiquity of Internet of Things (IoT) devices, the power consumption and security of IoT systems have become very important issues. Advanced Encryption Standard (AES) is a block cipher algorithm is commonly used in IoT devices. In this paper, the power consumption and cryptographic calculation requirement for different payload lengths and AES encryption types are analyzed. These types include software-based AES-CB, hardware-based AES-ECB (Electronic Codebook Mode), and hardware-based AES-CCM (Counter with CBC-MAC Mode). The calculation requirement and power consumption for these AES encryption types are measured on the Texas Instruments LAUNCHXL-CC1310 platform. The experimental results show that the hardware-based AES performs better than the software-based AES in terms of power consumption and calculation cycle requirements. In addition, in terms of AES mode selection, the AES-CCM-MIC64 mode may be a better choice if the IoT device is considering security, encryption calculation requirement, and low power consumption at the same time. However, if the IoT device is pursuing lower power and the payload length is generally less than 16 bytes, then AES-ECB could be considered.
Model calculations of the influence of population distribution on the siting of nuclear power plants
International Nuclear Information System (INIS)
Nielsen, F.; Walmod-Larsen, O.
1984-02-01
This report was prepared for a working group established in April 1981 by the Danish Environmental Protection Agency with the task of investigating siting problems of nuclear power stations in Denmark. The purpose of the working group was to study the influence of the population density around a site on nuclear power safety. The importance of emergency planning should be studied as well. In this model study two specific accident sequences were simulated on a 1000 MWe nuclear power plant. The plant was assumed to be placed in the center of two different model population distributions. The concequences for the two population distributions from the two accidents were calculated for the most frequent weather conditions. Doses to individuals were calculated for the bone marrow, lungs, gastrointestinal tract, thyroidea and for the whole body. The collective whole body doses were also calculated for the two populations considered. (author)
DEFF Research Database (Denmark)
Nash, Ulrik William
2014-01-01
Firms consist of people who make decisions to achieve goals. How do these people develop the expectations which underpin the choices they make? The lens model provides one answer to this question. It was developed by cognitive psychologist Egon Brunswik (1952) to illustrate his theory of probabil...
Directory of Open Access Journals (Sweden)
E. P. Zabello
2005-01-01
Full Text Available The method is proposed to make a correction in payment for consumption of reactive energy and power which is attributed to deviation of actual activation energy losses for reactive power compensation from their standard value. It is recommended to calculate standard loss values for every voltage level and actual loss values are to be determined with the help of application of remote electronic accounting means in the current mode of power consumption.
Calculation and Simulation Study on Transient Stability of Power System Based on Matlab/Simulink
Directory of Open Access Journals (Sweden)
Shi Xiu Feng
2016-01-01
Full Text Available The stability of the power system is destroyed, will cause a large number of users power outage, even cause the collapse of the whole system, extremely serious consequences. Based on the analysis in single machine infinite system as an example, when at the f point two phase ground fault occurs, the fault lines on either side of the circuit breaker tripping resection at the same time,respectively by two kinds of calculation and simulation methods of system transient stability analysis, the conclusion are consistent. and the simulation analysis is superior to calculation analysis.
Validation of the COBRA code for dry out power calculation in CANDU type advanced fuels
International Nuclear Information System (INIS)
Daverio, Hernando J.
2003-01-01
Stern Laboratories perform a full scale CHF testing of the CANFLEX bundle under AECL request. This experiment is modeled with the COBRA IV HW code to verify it's capacity for the dry out power calculation . Good results were obtained: errors below 10 % with respect to all data measured and 1 % for standard operating conditions in CANDU reactors range . This calculations were repeated for the CNEA advanced fuel CARA obtaining the same performance as the CANFLEX fuel. (author)
Consistent calculation of the stopping power for slow ions in two-dimensional electron gases
International Nuclear Information System (INIS)
Wang, You-Nian; Ma, Teng-Gai
1997-01-01
Within the framework of quantum scattering theory, we present a consistent calculation of the stopping power for slow protons and antiprotons moving in two-dimensional electron gases. The Friedel sum rule is used to determine the screening constant in the scattering potential. For the stopping power our results are compared with that of the random-phase approximation dielectric theory and that predicted by the linear Thomas-Fermi potential. copyright 1997 The American Physical Society
LC-lens array with light field algorithm for 3D biomedical applications
Huang, Yi-Pai; Hsieh, Po-Yuan; Hassanfiroozi, Amir; Martinez, Manuel; Javidi, Bahram; Chu, Chao-Yu; Hsuan, Yun; Chu, Wen-Chun
2016-03-01
In this paper, liquid crystal lens (LC-lens) array was utilized in 3D bio-medical applications including 3D endoscope and light field microscope. Comparing with conventional plastic lens array, which was usually placed in 3D endoscope or light field microscope system to record image disparity, our LC-lens array has higher flexibility of electrically changing its focal length. By using LC-lens array, the working distance and image quality of 3D endoscope and microscope could be enhanced. Furthermore, the 2D/3D switching ability could be achieved if we turn off/on the electrical power on LClens array. In 3D endoscope case, a hexagonal micro LC-lens array with 350um diameter was placed at the front end of a 1mm diameter endoscope. With applying electric field on LC-lens array, the 3D specimen would be recorded as from seven micro-cameras with different disparity. We could calculate 3D construction of specimen with those micro images. In the other hand, if we turn off the electric field on LC-lens array, the conventional high resolution 2D endoscope image would be recorded. In light field microscope case, the LC-lens array was placed in front of the CMOS sensor. The main purpose of LC-lens array is to extend the refocusing distance of light field microscope, which is usually very narrow in focused light field microscope system, by montaging many light field images sequentially focusing on different depth. With adjusting focal length of LC-lens array from 2.4mm to 2.9mm, the refocusing distance was extended from 1mm to 11.3mm. Moreover, we could use a LC wedge to electrically shift the optics axis and increase the resolution of light field.
FABGEN, a transient power-generation and isotope birth rate calculator
International Nuclear Information System (INIS)
Roland, H.C.
1975-04-01
A description is given of the FABGEN program, a fast-running program for calculating fuel element power-generation rates and selected fission product birth rates in a known neutron flux as functions of time. A first forward difference calculation is used, and the time step is one day. Provisions are made for including various fuel element lengths, variation of thermal flux with time, and use of different fertile isotopes. Five different fission products may be specified for birth-rate calculations. A daily summary may be output, or totals by days may be accumulated for final output. (U.S.)
The calculation and simulation of the ECRH HV power supply for the HL-2A tokamak
International Nuclear Information System (INIS)
Mao Xiaohui; Li Qing; Xuan Weimin; Yao Lieying
2006-01-01
In order to satisfy the requirement of ECRH, the ECRH HV power supply (ECHV-HVPS) on the base of high voltage pulse modulation has been designed. The filter inductance in the ECHV-HVPS is much smaller than the voltage regulation power supply. Modulations are adopted in the power supply, so the short time of the leading edge and lagging edge of the pulse is achieved. The main circuit of the ECHV-HVPS is showed. The equivalent resistance and the transient response of the PS are calculated and analyzed using MATLAB, and experiment results are given. (authors)
Approximative calculation of transient short-circuit currents in power-systems
Energy Technology Data Exchange (ETDEWEB)
Heuck, K; Rosenberger, R; Dettmann, K D; Kegel, R
1986-08-01
The paper shows that it is approximatively possible to calculate the transient short-circuit currents for symmetrical and asymmetrical faults in power-systems. For that purpose a simple equivalent network is found. Its error of approximation is small. For the important maximum short-circuit current limits of error are pointed out compared to VDE 0102.
Power and Sample Size Calculations for Logistic Regression Tests for Differential Item Functioning
Li, Zhushan
2014-01-01
Logistic regression is a popular method for detecting uniform and nonuniform differential item functioning (DIF) effects. Theoretical formulas for the power and sample size calculations are derived for likelihood ratio tests and Wald tests based on the asymptotic distribution of the maximum likelihood estimators for the logistic regression model.…
International Nuclear Information System (INIS)
Lim, Chang Hyun; Jung Yeon Sang; Joo Han Gyu
2012-01-01
It was generally known that the Doppler feedback effect computed by most industrial reactor analysis codes is underestimated than the actual values. Part of the underestimation was attributed to the neglect of the resonance upscattering during the slowing down calculation. On the contrary, the edge peaked power profile noted in burned fuel pins due to more plutonium buildup at the periphery of fuel pellets might lead to smaller power defects than the predicted values obtained with a flat profile. This work is to mitigate these problems with a direct whole core calculation code nTRACER which is capable of handling ringwise depletion as well as incorporating nonuniform power profiles inside a fuel pellet
Calculation methods of reactivity using derivatives of nuclear power and Filter fir
International Nuclear Information System (INIS)
Diaz, Daniel Suescun
2007-01-01
This work presents two new methods for the solution of the inverse point kinetics equation. The first method is based on the integration by parts of the integral of the inverse point kinetics equation, which results in a power series in terms of the nuclear power in time dependence. Applying some conditions to the nuclear power, the reactivity is represented as first and second derivatives of this nuclear power. This new calculation method for reactivity has special characteristics, amongst which the possibility of using different sampling periods, and the possibility of restarting the calculation, after its interruption associated it with a possible equipment malfunction, allowing the calculation of reactivity in a non-continuous way. Apart from this reactivity can be obtained with or without dependency on the nuclear power memory. The second method is based on the Laplace transform of the point kinetics equations, resulting in an expression equivalent to the inverse kinetics equation as a function of the power history. The reactivity can be written in terms of the summation of convolution with response to impulse, characteristic of a linear system. For its digital form the Z-transform is used, which is the discrete version of the Laplace transform. In this method it can be pointed out that the linear part is equivalent to a filter named Finite Impulse Response (Fir). The Fir filter will always be, stable and non-varying in time, and, apart from this, it can be implemented in the non-recursive way. This type of implementation does not require feedback, allowing the calculation of reactivity in a continuous way. The proposed methods were validated using signals with random noise and showing the relationship between the reactivity difference and the degree of the random noise. (author)
Directory of Open Access Journals (Sweden)
V. N. Radkevich
2016-01-01
Full Text Available The indicators of power consumption of lighting devices based on LEDs are studied depending on the supplied voltage. For the lamp and floodlight with LEDs active and reactive power, current and power factor as a function of voltage (which value changed in the range 200–245 V were experimentally determined. The analysis of experimental data demonstrated that due to the drivers in the specified voltage range the active power consumed by light devices remains practically unchanged. The reactive power of LED devices depends on the supplied voltage and is capacitive in its nature. In contrast with gas-discharge light sources the LED devices under study do not consume reactive power, but generate it. With the change of the supplied voltage from 200 to 245 V the value of the generated reactive power increases to 60 % for the floodlight and 50 % for the lamp. The LED floodlight has a low coefficient of active power. The current consumed by the floodlight has increased by 22 %, and by the lamp – by 13 %. The formulas for determining the maximum value of the length of the calculated section of single-phase group lines were developed, taking into account specific source data. LED light sources tend to feed by electric power by single-phase group lines. The number of lamps connected to single-phase lines is regulated by normative documents. Bearing this in mind as well as the small power of LED sources single-phase group lines are usually performed with conductors of the smallest possible cross section. The limit values of the length of the calculated section that correspond to a predetermined loss of voltage in line with ambient temperature from 15 to 60 °С were determined for them. The calculations demonstrated that for group lines that feed the LEDs, the choice of conductor cross-sections in accordance with permissible voltage loss is not critical. The determinant factor for the choice of the cross-section of the conductors of group electrical
Fradi, Aniss
The ability to allocate the active power (MW) loading on transmission lines and transformers, is the basis of the "flow based" transmission allocation system developed by the North American Electric Reliability Council. In such a system, the active power flows must be allocated to each line or transformer in proportion to the active power being transmitted by each transaction imposed on the system. Currently, this is accomplished through the use of the linear Power Transfer Distribution Factors (PTDFs). Unfortunately, no linear allocation models exist for other energy transmission quantities, such as MW and MVAR losses, MVAR and MVA flows, etc. Early allocation schemes were developed to allocate MW losses due to transactions to branches in a transmission system, however they exhibited diminished accuracy, since most of them are based on linear power flow modeling of the transmission system. This thesis presents a new methodology to calculate Energy Transaction Allocation factors (ETA factors, or eta factors), using the well-known process of integration of a first derivative function, as well as consistent and well-established mathematical and AC power flow models. The factors give a highly accurate allocation of any non-linear system quantity to transactions placed on the transmission system. The thesis also extends the new ETA factors calculation procedure to restructure a new economic dispatch scheme where multiple sets of generators are economically dispatched to meet their corresponding load and their share of the losses.
International Nuclear Information System (INIS)
Yu, L.H.
1998-01-01
Recent advances in self-amplified spontaneous emission (SASE) experiments stimulate interest in quantitative comparison of measurements with theory. In this paper we show that the widely used simulation code TDA3D, developed by Tran and Wurtele [Comput. Phys. Commun. 54, 263 (1989)] even though a single frequency code, can be used to determine the output power in the SASE process with excellent approximation in the exponential growth regime. The method applies when the gain is not very high, which is a special advantage, because when the gain is not very high, the analytical calculation is particularly difficult since the exponential growing term does not dominate. The analysis utilizes a scaling relation between the output power and the number of simulation particles in the code TDA3D: left-angle P right-angle=N λ ' /N λ left-angle P ' right-angle, where left-angle P right-angle is the output power and N λ is the line density of the electrons, while left-angle P ' right-angle is the calculated output power using a line density N λ ' of the number of simulation particles in the code TDA3D. Because of the scaling property, the number of simulation particles can be taken to be many orders of magnitude less than the actual experiment. Comparison of our results with experiment yields new insight into the SASE process. copyright 1998 The American Physical Society
Directory of Open Access Journals (Sweden)
Palukuru NAGENDRA
2010-12-01
Full Text Available In this study, the use of artificial neural network (ANN based model, multi-layer perceptron (MLP network, to compute the transfer capabilities in a multi-area power system was explored. The input for the ANN is load status and the outputs are the transfer capability among the system areas, voltage magnitudes and voltage angles at concerned buses of the areas under consideration. The repeated power flow (RPF method is used in this paper for calculating the power transfer capability, voltage magnitudes and voltage angles necessary for the generation of input-output patterns for training the proposed MLP neural network. Preliminary investigations on a three area 30-bus system reveal that the proposed model is computationally faster than the conventional method.
International Nuclear Information System (INIS)
Serov, I.V.; Hoogenboom, J.E.
1996-01-01
A technique for the statistical confluence of any number of possibly correlated informational sources employed in reactor analysis can be used to improve the estimates of physical quantities given by the sources taken separately. The formulas of the presented technique being based on multivariate Bayesian conditioning are general and can be employed in different applications. Insight into the nature of the informational source allows different types of data associated with the source to be improved. Estimation of biases, variances and correlation coefficients for the systematic and statistical errors associated with the informational sources is reliable confluence, but pays off by providing optimal estimates. The technique of the calculational and experimental information confluence is applied to the determination of the power distribution and burnup for the research reactor HOR of the Delft University of Technology. The code system CONHOR carries out all the stages of the calculation for the HOR reactor, using an existing code for static core calculations and burnup calculations. (author)
Energy Technology Data Exchange (ETDEWEB)
Serov, I.V.; Hoogenboom, J.E. [Interuniversitair Reactor Inst., Delft (Netherlands)
1996-05-01
A technique for the statistical confluence of any number of possibly correlated informational sources employed in reactor analysis can be used to improve the estimates of physical quantities given by the sources taken separately. The formulas of the presented technique being based on multivariate Bayesian conditioning are general and can be employed in different applications. Insight into the nature of the informational source allows different types of data associated with the source to be improved. Estimation of biases, variances and correlation coefficients for the systematic and statistical errors associated with the informational sources is reliable confluence, but pays off by providing optimal estimates. The technique of the calculational and experimental information confluence is applied to the determination of the power distribution and burnup for the research reactor HOR of the Delft University of Technology. The code system CONHOR carries out all the stages of the calculation for the HOR reactor, using an existing code for static core calculations and burnup calculations. (author).
Analysis of offsite dose calculation methodology for a nuclear power reactor
International Nuclear Information System (INIS)
Moser, D.M.
1995-01-01
This technical study reviews the methodology for calculating offsite dose estimates as described in the offsite dose calculation manual (ODCM) for Pennsylvania Power and Light - Susquehanna Steam Electric Station (SSES). An evaluation of the SSES ODCM dose assessment methodology indicates that it conforms with methodology accepted by the US Nuclear Regulatory Commission (NRC). Using 1993 SSES effluent data, dose estimates are calculated according to SSES ODCM methodology and compared to the dose estimates calculated according to SSES ODCM and the computer model used to produce the reported 1993 dose estimates. The 1993 SSES dose estimates are based on the axioms of Publication 2 of the International Commission of Radiological Protection (ICRP). SSES Dose estimates based on the axioms of ICRP Publication 26 and 30 reveal the total body estimates to be the most affected
Methodology and conclusions of activation calculations of WWER-440 type nuclear power plants
Energy Technology Data Exchange (ETDEWEB)
Babcsány, Boglárka, E-mail: boglarka.babcsany@reak.bme.hu; Czifrus, Szabolcs; Fehér, Sándor
2015-04-01
Highlights: • Activation calculation of two WWER-440 type nuclear power plants. • Detailed description of the applied activation calculation methodology. • Graphical results for total activity and waste index categorization. • General conclusions for activation applicable in the case of PWR reactors. - Abstract: Activation calculations for two nuclear power plants of WWER-440 type have been performed by the authors in order to assist the decommissioning planning by assessing the radioactive inventory present at the time of and at different times after the final shutdown. According to related international literature and studies performed earlier by the authors, considering the activity more than 99% of this inventory is concentrated in the materials directly surrounding the reactor core, where the predominant evolution of radionuclides is generated by neutron induced nuclear reactions. In order to obtain the highest possible accuracy in modelling, three-dimensional Monte Carlo neutron transport calculations were performed. Besides the methods and models applied to these analyses, the paper also summarizes the results that can be generally applied to such nuclear power plant types. At the time of shutdown, the total activity of the stainless steel components is about 6 × 10{sup 16} Bq and 1.3 × 10{sup 17} Bq for the two NPPs considered. The biological shielding concrete constitutes approximately 7 × 10{sup 13} Bq and 1.1 × 10{sup 14} Bq.
International Nuclear Information System (INIS)
Majer, P.
1990-01-01
The fundamentals are outlined of the discounted value flows method, which is used in industrial countries for calculating the specific electricity production costs. Actual calculations were performed for the first two units of the Temelin nuclear power plant. All costs associated with the construction, operation and decommissioning of this nuclear power plant were taken into account. With a high degree of certainty, the specific production costs of the Temelin nuclear power plant will lie within the range of 0.32 to 0.36 CSK/kWh. Nearly all results of the sensitivity analysis performed for the possible changes in the input values fall within this range. An increase in the interest rate to above 8% is an exception; this, however, can be regarded as rather improbable on a long-term basis. Sensitivity analysis gave evidence that the results of the electricity production cost calculations for the Temelin nuclear power plant can be considered sufficiently stable. (Z.M.). 7 figs., 2 tabs., 14 refs
International Nuclear Information System (INIS)
Ondra, Frantisek; Daniska, Vladimir; Rehak, Ivan; Necas, Vladimir
2009-01-01
The aim of the article is a development of analytical methodology for evaluation of input data inaccuracies impact on calculation of cost and other output decommissioning parameters. This methodology is based on analytical model calculations using the OMEGA code and taking into account the probability of input data inaccuracies occurrence also. To achieve about mentioned aim, the article identifies possible sources of input data inaccuracies and analyzes their level of impact on output parameters. Then the methodology for calculation of input parameters inaccuracies impact is developed, based on analytical model calculation. The model calculation takes into consideration output parameters impact on cost and other decommissioning output parameters in analytical way. The methodology used in model calculations is original, more over it implements the international standardized structure (IAEA, OECD/NEA, EC) [6] of decommissioning cost for the first time. A probabilistic occurrence of input data inaccuracies is taken into consideration and implemented in the methodology developed. A correction factors matrix for evaluation of input data inaccuracies impact on decommissioning output parameters is set up. The matrix contains parameters based on model calculations using the proposed methodology. Finally the methodology for application of correction factor matrix is proposed and tested; the methodology is used for calculation of contingency in the standardized structure which reflected the level of input data inaccuracies. The cost for individual decommissioning projects for common nuclear power plants are in the range 300 - 500 mil. EUR. Contingencies are from 10% to 30%, depending on the level of detailed during preparation of decommissioning projects. A implementation about mentioned methodology in the OMEGA code improves the accuracy of contingency. Consequently it makes calculated contingency more trustworthy and makes calculated decommissioning cost closer to reality
Martin, Heiner; Guthoff, Rudolf; Schmitz, Klaus-Peter
2011-09-01
Polymer injection into the capsular bag after phakoemulsification is an interesting and promising approach to lens surgery. Safe clinical application of this technique will require an appropriate estimate of the effect of implantation variables on the lens power. This article details the results of finite element investigations into the effects of the injected polymer volume and capsular bag contraction on the resultant lens power and accommodation amplitude. An axisymmetric finite element model was created from literature sources. Polymer injection and the capsular contraction were simulated, and their effect on the lens power was calculated. The simulations show that overfilling during polymer injection leads to a refractive power increase of the lens. Capsular bag contraction also results in a power increase. The calculated accommodative amplitude of the lens is minimally affected by capsular bag contraction but decreases significantly with increased capsular bag stiffness as a result of fibrosis. © 2010 The Authors. Journal compilation © 2010 Acta Ophthalmol.
Motor power calculation for driving conveyor chain in gamma irradiator BATAN 2x250 k curie
International Nuclear Information System (INIS)
Ari Satmoko; Syamsurrijal Ramdja; Sutomo Budihardjo
2010-01-01
Recently, an Irradiator BATAN 2X250 k Curie for agricultural product is under design. The installation is provided by the gamma source about 2x250 k Curie. Agricultural products are carried into carriers and these carriers are hanged on the conveyor chain. The chain moves into a radiation chamber following the trajectoire. The chain is drived by motor. For this reason, the calculation is performed to determine the motor power. After resolving the force equilibrium equation, the force and power of the motor needed to drive the chain are obtained. Numerical method by using V Basic language is used to resolve the equation. The calculation result shows the correlation between friction coefficient and motor power. From the evaluation, it is decided that the friction coefficient should be less than 0,015. By this friction, the motor power is about 3. 13 k Watt. From the evaluation, it is also obtained that the radius of the curve trajectory shall not be too small. Combination between high friction and small curve radius could lead to the locked condition in which high power motor are not be able to move the conveyor chain). (author)
Finite element method used in strength calculations of nuclear power plant pressure vessels
International Nuclear Information System (INIS)
Hanulak, E.
1987-01-01
A software system based on the use of the finite element method in linear and nonlinear elastomechanics was developed for assessing the strength and service life of steam generators and pressurizers for WWER type nuclear power plants. The individual programs are briefly described. They are written in FORTRAN IV, some modules are in ASSEMBLER. Programs EGUSAP, NEANKO, ROSYNA are designed for the calculation of stress and deformation, programs ROSYNA, NEANKO and NTEPLO are used for the calculation of temperature fields. Programs SPOJ and STATES are used for assessing the strength and service life of screw joints and other nodes of the WWER-440 type steam generators and pressurizers. (Z.M.)
Preliminary results on food consumption rates for off-site dose calculation of nuclear power plants
International Nuclear Information System (INIS)
Lee, Gab Bock; Chung, Yang Geun; Bang, Sun Young; Kang, Duk Won
2005-01-01
The Internal dose by food consumption mostly account for radiological dose of public around nuclear power plants(NPP). But, food consumption rate applied to off-site dose calculation in Korea which is the result of field investigation around Kori NPP by the KAERI in 1988. is not reflected of the latest dietary characteristics. The Ministry of Health and Welfare Affairs has investigated the food and nutrition of nations every 3 years based on the Law of National Health Improvement. To update the food consumption rates of the maximum individual, the analysis of the national food investigation results and field surveys around nuclear power plant sites have been carried out
International Nuclear Information System (INIS)
Valentine, T.E.; Mihalczo, J.T.
1996-01-01
One primary concern for design of safety systems for reactors is the time response of external detectors to changes in the core. This paper describes a way to estimate the time delay between the core power production and the external detector response using Monte Carlo calculations and suggests a technique to measure the time delay. The Monte Carlo code KENO-NR was used to determine the time delay between the core power production and the external detector response for a conceptual design of the Advanced Neutron Source (ANS) reactor. The Monte Carlo estimated time delay was determined to be about 10 ms for this conceptual design of the ANS reactor
Chapter 03: Correct use of a hand lens
Alex Wiedenhoeft
2011-01-01
A hand lens is a powerful tool for the identification of wood, but like all tools it must be used correctly to take full advantage of its powers. The hand lens has two main parts, a lens that magnifies the object of interest (generally we use 10X or 14X lenses in wood identification; a 14X lens is recommended for use with this manual) and a housing to hold and protect...
Calculation of the local power peaking near WWER-440 control assemblies with Hf plates
International Nuclear Information System (INIS)
Hegyi, Gy.; Hordosy, G.; Kereszturi, A.; Maraszy, Cs.; Temesvari, E.
2003-01-01
The original coupler design of the WWER-440 assemblies had the following well known deficiency: The relatively large amount of water in the coupler between the absorber and fuel port of the control assembly can cause undesirably sharp power peaking in the fuel rods next to the coupler. The power peaking can be especially high after control rod withdrawal when the coupler reached low burnup level region of the adjacent assembly. The modernized coupler design overcomes the original problem by applying a thin Hf plate in the critical region. The very complicated structure of the coupler requires the verification of the core design methods by high precision 3D Monte Carlo calculations. The paper presents an MCNP reference calculation on the control rod coupler benchmark with Hf absorber plates. The benchmark solution with the KARATE-440 code system is also presented. The need for treating the Hf burnout in the reflector region is investigated (Authors)
Calculation of the power factor using the neutron diffusion hybrid equation
International Nuclear Information System (INIS)
Costa da Silva, Adilson; Carvalho da Silva, Fernando; Senra Martinez, Aquilino
2013-01-01
Highlights: ► A neutron diffusion hybrid equation with an external neutron source was used. ► Nodal expansion method to obtain the neutron flux was used. ► Nuclear power factors in each fuel element in the reactor core were calculated. ► The results obtained were very accurate. -- Abstract: In this paper, we used a neutron diffusion hybrid equation with an external neutron source to calculate nuclear power factors in each fuel element in the reactor core. We used the nodal expansion method to obtain the neutron flux for a given control rods bank position. The results were compared with results obtained for eigenvalue problem near criticality condition and fixed source problem during the start-up of the reactor, where external neutron sources are extremely important for the stabilization of external neutron detectors.
Erosion corrosion in power plant piping systems - Calculation code for predicting wall thinning
International Nuclear Information System (INIS)
Kastner, W.; Erve, M.; Henzel, N.; Stellwag, B.
1990-01-01
Extensive experimental and theoretical investigations have been performed to develop a calculation code for wall thinning due to erosion corrosion in power plant piping systems. The so-called WATHEC code can be applied to single-phase water flow as well as to two-phase water/steam flow. Only input data which are available to the operator of the plant are taken into consideration. Together with a continuously updated erosion corrosion data base the calculation code forms one element of a weak point analysis for power plant piping systems which can be applied to minimize material loss due to erosion corrosion, reduce non-destructive testing and curtail monitoring programs for piping systems, recommend life-extending measures. (author). 12 refs, 17 figs
Calculation of the stopping power and the path of charged particles in matter. Application example
International Nuclear Information System (INIS)
Barre, Bertrand; Du Lieu, Pierre
1969-05-01
The path of a charged particle in matter is calculated by integrating the stopping power of the medium against this particle. Depending on the energy of the particle, stopping powers are calculated using Lindhard, Bethe, or semi-empirical smoothing solutions. After exposing recent theories in this field, the authors present a Fortran subroutine which performs these various operations, and covers all energy domains. This routine is available for operation on IBM 360; it uses a magnetic tape library that can take into account experimental results. The subprogram presentation, leaving the user the option of entering the data and using the results at his discretion, allows a particularly flexible use. At the end of this note, some considerations on possible further improvements in the program, and a bibliography of the articles that have dealt with the question from a theoretical or an experimental point of view are discussed [fr
Calculation of Savannah River K Reactor Mark-22 assembly LOCA/ECS power limits
International Nuclear Information System (INIS)
Fischer, S.R.; Farman, R.F.; Birdsell, S.A.
1992-01-01
This paper summarizes the results of TRAC-PF1/MOD3 calculations of Mark-22 fuel assembly of loss-of-coolant accident/emergency cooling system (LOCA/ECS) power limits for the Savannah River Site (SRS) K Reactor. This effort was part of a larger effort undertaken by the Los Alamos National Laboratory for the US Department of Energy to perform confirmatory power limits calculations for the SRS K Reactor. A method using a detailed three-dimensional (3D) TRAC model of the Mark-22 fuel assembly was developed to compute LOCA/ECS power limits. Assembly power was limited to ensure that no point on the fuel assembly walls would exceed the local saturation temperature. The detailed TRAC model for the Mark-22 assembly consisted of three concentric 3D vessel components which simulated the two targets, two fuel tubes, and three main flow channels of the fuel assembly. The model included 100% eccentricity between the assembly annuli and a 20% power tilt. Eccentricity in the radial alignment of the assembly annuli arises because axial spacer ribs that run the length of the fuel and targets are used. Wall-shear, interfacial-shear, and wall heat-transfer correlations were developed and implemented in TRAC-PF1/MOD3 specifically for modeling flow and heat transfer in the narrow ribbed annuli encountered in the Mark-22 fuel assembly design. We established the validity of these new constitutive models using separate-effects benchmarks. TRAC system calculations of K Reactor indicated that the limiting ECS-phase accident is a double-ended guillonite break in a process water line at the pump discharge (i.e., a PDLOCA). The fuel assembly with the minimum cooling potential is identified from this system calculation. Detailed assembly calculations then were performed using appropriate boundary conditions obtained from this limiting system LOCA. Coolant flow rates and pressure boundary conditions were obtained from this system calculation and applied to the detailed assembly model
Correction of the calculation of beam loading based in the RF power diffusion equation
International Nuclear Information System (INIS)
Silva, R. da.
1980-01-01
It is described an empirical correction based upon experimental datas of others authors in ORELA, GELINA and SLAC accelerators, to the calculation of the energy loss due to the beam loading effect as stated by the RF power diffusion equation theory an accelerating structure. It is obtained a dependence of this correction with the electron pulse full width half maximum, but independent of the electron energy. (author) [pt
The Davidson Method as an alternative to power iterations for criticality calculations
International Nuclear Information System (INIS)
Subramanian, C.; Van Criekingen, S.; Heuveline, V.; Nataf, F.; Have, P.
2011-01-01
The Davidson method is implemented within the neutron transport core solver parafish to solve k-eigenvalue criticality transport problems. The parafish solver is based on domain decomposition, uses spherical harmonics (P_N method) for angular discretization, and nonconforming finite elements for spatial discretization. The Davidson method is compared to the traditional power iteration method in that context. Encouraging numerical results are obtained with both sequential and parallel calculations. (author)
POPCYCLE: a computer code for calculating nuclear and fossil plant levelized life-cycle power costs
International Nuclear Information System (INIS)
Hardie, R.W.
1982-02-01
POPCYCLE, a computer code designed to calculate levelized life-cycle power costs for nuclear and fossil electrical generating plants is described. Included are (1) derivations of the equations and a discussion of the methodology used by POPCYCLE, (2) a description of the input required by the code, (3) a listing of the input for a sample case, and (4) the output for a sample case
Audit Calculations of ATWS for Ulchin Unit 1 and 2 Power Uprate
Energy Technology Data Exchange (ETDEWEB)
Lee, Jun Soo; Huh, Byung Gil; Choi, Yong Seog; Seul, Kwang Won [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)
2013-10-15
In this study, the regulatory audit calculation for ATWS of Ulchin Unit 1 and 2 with 4.5% power uprate was performed to support the licensing review and to confirm the validity of licensee's calculation. In order to simulate the transient behavior of ATWS initiated by a loss of feed water, the systems of Ulchin Unit 1 and 2 was modeled with MARS-KS 1.3. In this study, the regulatory audit calculation of ATWS for Ulchin 1 and 2 with 4.5% power uprating and 99% MTC in the specific cycle designs was performed. It is conformed that the analysis results of ATWS for Ulchin 1 and 2 power uprate meets the RCS pressure acceptance criteria. An anticipated transient accompanied by a failure in the Reactor Trip System (RTS) to shut down the reactor is defined as an Anticipated Transient Without Scram (ATWS). Under certain postulated conditions, the ATWS could lead to Reactor Coolant system (RCS) pressure boundary fracture and/or core damage. For a conventional pressurized water reactor (PWR), the temperature corresponding to the NSSC notice No.2013.09(Performance Criteria for ECCS of the Pressurized Water Reactor Nuclear Power Plants), 1204 .deg. C and the pressure corresponding to the ASME Boiler and Pressure Vessel Code service level C stress, 221.5 bar is assumed to be an unacceptable plant condition against ATWS, above which the RCS pressure boundary could deform to the point of inoperability and the safe shutdown by injection of borated water could be challenged. Such potentially excessive RCS overpressure may occur in the ATWS initiated from a loss of heat sink. Currently, the modification of Ulchin 1 and 2 operating license for 4.5% power uprate is under review.
Calculation of the Power Peaking Factor Using CFNN and Its Uncertainty Analysis
Energy Technology Data Exchange (ETDEWEB)
Back, Ju Hyun; Kim, Dong Yeong; Yoo, Kwae Hwan; Choi, Geon Pil; Na, Man Gyun [Chosun University, Gwangju (Korea, Republic of)
2016-05-15
The local power density (LPD) and DNBR must be calculated in order to perform the main functions of the core protection calculator (CPC) and the core operation limit supervisory system (COLSS). CPC and COLSS play a role in the protection and monitoring systems of the optimized power reactor 1000 (OPR1000) and the advanced power reactor 1400 (APR1400). LPD should be estimated accurately to prevent fuel rods from melting. LPD at the hottest part of the core is called the power peaking factor (PPF, F{sub q} ). LPD at the hottest part of the core is more important than LPD at any other position in a reactor core. DNBR and PPF are the most important factors that must be continuously monitored from a safety aspect. The aim of the study is to calculate PPF in a reactor core by a cascaded fuzzy neural networks (CFNN) model according to operating conditions. The operation condition is reactor power, core inlet temperature, pressurizer pressure, mass flowrate, axial shape index (ASI), and variety of control rod position. The proposed CFNN model that is a PPF estimation algorithm is verified by using the nuclear and thermal data acquired from numerical simulations of OPR1000. The CFNN regression models were optimized by using the data set prepared as training data and tested by using verification data. The developed CFNN models were applied to the OPR 1000. As a result, the RMS error of the estimated PPF values is below 0.05%. In addition, their uncertainty was analyzed by a bootstrap method using 100 sampled development data sets.
Influential parameters for designing and power consumption calculating of cumin mower
Energy Technology Data Exchange (ETDEWEB)
Mahmoodi, E.; Jafari, A. [Tehran Univ., Karaj (Iran, Islamic Republic of). Dept. of Agricultural Machinery Engineering
2010-07-01
This paper reported on a study in which the consuming power and design of cumin mowers was calculated. The parameters required for calculating power consumption and designing of cumin mowers were measured along with some engineering properties of cumin stems. These included shearing and bending tests on cumin stem and specifying the coefficient of friction between mower knives and cumin stem. The relationships between static and dynamic friction forces being exerted on mower runners by soil with normal load were determined along with the factor affecting soil moisture. Some of the other parameters that are important for calculating the power consumption and design of an optimized mower include harvest moisture content; maximum and average of cumin stem diameter; maximum bio-yield point of force and maximum ultimate point of force in the cutting; average energy required to cut a stem; maximum elasticity module; maximum bending rupture force; average energy required for bending a stem; friction coefficient between the stem and knife edge; relation between bio-yield force, failure force, elasticity and diameter in the cutting; relation between rupture forces and diameter in the bending; and mower weight.
Preliminary reactor physics calculations for Exxon LWR fuel testing in the power burst facility
International Nuclear Information System (INIS)
Olson, W.O.; Nigg, D.W.
1981-05-01
The PFB reactor is being considered as an irradiation facility to test LWR fuel rods for Exxon Nuclear Company. Requested test conditions are 18 kW/ft axial peak steady state power in 2.5% initial enrichment, 20,000 MWd/Tu exposed rods. Multigroup transport theory calculations (S/sub n/ and Monte Carlo) showed that this was unattainable in the standard PBF test loop. Thus, a flux multiplier was developed in the form of a Zr-2-clad 0.15-inch thick cylindrical shell of 35% enriched, 88% T.D. UO 2 replacing the flow divider, surrounding the rod within the in-pile tube in PFB. With this flux multiplier installed and assuming an average water density of 0.86 g/cm 3 within the test loop, a Figure of Merit (FOM) for a single-rod test assembly of 0.86 kW/ft-MW +- 5% (at 95% confidence level) was calculated. This FOM is the axial peak linear test rod power per megawatt of reactor power. A reactor power of about 21 megawatts will therefore be required to supply the requested linear test rod axial peak heating rate of 18 kW/ft
EBRPOCO - a program to calculate detailed contributions of power reactivity components of EBR-II
International Nuclear Information System (INIS)
Meneghetti, D.; Kucera, D.A.
1981-01-01
The EBRPOCO program has been developed to facilitate the calculations of the power coefficients of reactivity of EBR-II loadings. The program enables contributions of various components of the power coefficient to be delineated axially for every subassembly. The program computes the reactivity contributions of the power coefficients resulting from: density reduction of sodium coolant due to temperature; displacement of sodium coolant by thermal expansions of cladding, structural rods, subassembly cans, and lower and upper axial reflectors; density reductions of these steel components due to temperature; displacement of bond-sodium (if present) in gaps by differential thermal expansions of fuel and cladding; density reduction of bond-sodium (if present) in gaps due to temperature; free axial expansion of fuel if unrestricted by cladding or restricted axial expansion of fuel determined by axial expansion of cladding. Isotopic spatial contributions to the Doppler component my also be obtained. (orig.) [de
Directory of Open Access Journals (Sweden)
A.V. Erisov
2016-05-01
Full Text Available Purpose. Simplification of accounting ratio to determine the magnetic field strength of electric power lines, and assessment of their environmental safety. Methodology. Description of the transmission lines of the magnetic field by using techniques of spatial harmonic analysis in the cylindrical coordinate system is carried out. Results. For engineering calculations of electric power lines magnetic field with sufficient accuracy describes their first spatial harmonic magnetic field. Originality. Substantial simplification of the definition of the impact of the construction of transmission line poles on the value of its magnetic field and the bands of land alienation sizes. Practical value. The environmentally friendly projection electric power lines on the level of the magnetic field.
Corneal Anterior Power Calculation for an IOL in Post-PRK Patients.
De Bernardo, Maddalena; Iaccarino, Stefania; Cennamo, Michela; Caliendo, Luisa; Rosa, Nicola
2015-02-01
After corneal refractive surgery, there is an overestimation of the corneal power with the devices routinely used to measure it. Therefore, the objective of this study was to determine whether, in patients who underwent photorefractive keratectomy (PRK), it is possible to predict the earlier preoperative anterior corneal power from the postoperative (PO) posterior corneal power. A comparison is made using a formula published by Saiki for laser in situ keratomileusis patients and a new one calculated specifically from PRK patients. The Saiki formula was tested in 98 eyes of 98 patients (47 women) who underwent PRK for myopia or myopic astigmatism. Moreover, anterior and posterior mean keratometry (Km) values from a Scheimpflug camera were measured to obtain a specific regression formula. The mean (±SD) preoperative Km was 43.50 (±1.39) diopters (D) (range, 39.25 to 47.05 D). The mean (±SD) Km value calculated with the Saiki formula using the 6 months PO posterior Km was 42.94 (±1.19) D (range, 40.34 to 45.98 D) with a statistically significant difference (p PRK in our patients, the posterior Km was correlated with the anterior preoperative one by the following regression formula: y = -4.9707x + 12.457 (R² = 0.7656), where x is PO posterior Km and y is preoperative anterior Km, similar to the one calculated by Saiki. Care should be taken in using the Saiki formula to calculate the preoperative Km in patients who underwent PRK.
Neutronic calculations for the reactor pressure vessel of Atucha I nuclear power plant
International Nuclear Information System (INIS)
Lerner, Ana M.; Madariaga, Marcelo R.
1999-01-01
In 1974 a surveillance program for the Atucha I nuclear power plant pressure vessel was initiated which included the construction of different types of specimens, distributed in 30 irradiation capsules located under the core at the lower part of some of the fuel channels. The capsules containing the irradiated specimens were withdrawn in two stages; the first set (SET 1) of 15 specimens in 1980 and the second one (SET 2) of the remaining 15, in 1987. Both fracture mechanic tests and dosimetry analysis were carried out by the designer (KWU) for SET1 and by the owner National Atomic Energy Commission (CNEA) for SET2. The calculations performed in the case of SET1 showed that there was a significant spectrum difference between the position where the specimens had been and the reactor pressure vessel (RPV) - inner surface (IS). It was established that the ratio of thermal flux (E 1 MeV) varied, approximately, from 1000 to 10 from the irradiation position to the RPV- IS. The purpose of this report is to show the calculations recently performed at the Nuclear Regulatory Authority, with particular emphasis on the difference in the results generated by the modification to sightly enriched fuel. A simplified 1-D calculations show that there is a slight increase (4% approximately) in the flux along the whole energy range. As it has already been mentioned, this is due, more than to the isotopic composition of the new fuel, to the difference in power density spatial distribution, which is a consequence of a different fuel management, necessary to preserve operational limits below their maximum allowed values with the same total thermal power generated. More detailed calculations are nevertheless foreseen in order to verify these first results. (author)
Cheng, Chih-Wen; Hua, Jian; Hwang, Daw-Shang
2017-10-01
An important marine pollution issue identified by the International Maritime Organization (IMO) is NO x emissions; however, the stipulated method for determining the NO x certification value does not reflect the actual high emission factors of slow-speed two-stroke diesel engines over long-term slow steaming. In this study, an accurate method is presented for calculating the NO x emission factors and total amount of NO x emissions by using the actual power probabilities of the diesel engines in four types of bulk carriers. The proposed method is suitable for all types and purposes of diesel engines, is not restricted to any operating modes, and is highly accurate. Moreover, it is recommended that the IMO-stipulated certification value calculation method be modified accordingly to genuinely reduce the amount of NO x emissions. The successful achievement of this level of reduction will help improve the air quality, especially in coastal and port areas, and the health of local residents. As per the IMO, the NO x emission certification value of marine diesel engines having a rated power over 130 kW must be obtained using specified weighting factor (WF)-based calculation. However, this calculation fails to represent the current actual situation. Effective emission reductions of 6.91% (at sea) and 31.9% (in ports) were achieved using a mathematical model of power probability functions. Thus, we strongly recommend amending the certification value of NO x Technical Code 2008 (NTC 2008) by removing the WF constraints, such that the NO x emissions of diesel engines is lower than the Tier-limits at any load level to obtain genuine NO x emission reductions.
A nodal method of calculating power distributions for LWR-type reactors with square fuel lattices
International Nuclear Information System (INIS)
Hoeglund, Randolph.
1980-06-01
A nodal model is developed for calculating the power distribution in the core of a light water reactor with a square fuel lattice. The reactor core is divided into a number of more or less cubic nodes and a nodal coupling equation, which gives the thermal power density in one node as a function of the power densities in the neighbour nodes, is derived from the neutron diffusion equations for two energy groups. The three-dimensional power distribution can be computed iteratively using this coupling equation, for example following the point Jacobi, the Gauss-Seidel or the point successive overrelaxation scheme. The method has been included as the neutronic model in a reactor core simulation computer code BOREAS, where it is combined with a thermal-hydraulic model in order to make a simultaneous computation of the interdependent power and void distributions in a boiling water reactor possible. Also described in this report are a method for temporary one-dimensional iteration developed in order to accelerate the iterative solution of the problem and the Haling principle which is widely used in the planning of reloading operations for BWR reactors. (author)
International Nuclear Information System (INIS)
Moch Djoko Birmano; Imam Bastori
2008-01-01
The study for calculating the economic and financing of Nuclear Power Plant (NPP) and conventional power plant using spreadsheet Innovation has been done. As case study, the NPP of PWR type of class 1050 MWe is represented by OPR-1000 (Optimized Power Reactor, 1000 MWe) and the conventional plant of class 600 MWe, is coal power plant (Coal PP). The purpose of the study is to assess the economic and financial feasibility level of OPR-1000 and Coal PP. The study result concludes that economically, OPR-1000 is more feasible compared to Coal PP because its generation cost is cheaper. Whereas financially, OPR-1000 is more beneficial compared to Coal PP because the higher benefit at the end of economic lifetime (NPV) and the higher ratio of benefit and cost (B/C Ratio). For NPP and Coal PP, the higher Discount Rate (%) is not beneficial. NPP is more sensitive to the change of discount rate compared to coal PP, whereas Coal PP is more sensitive to the change of power purchasing price than NPP. (author)
International Nuclear Information System (INIS)
Liu Yang; Cai Qi; Lin Xiaoling
2011-01-01
Based on the operation characteristics of the nuclear power unit, the radioactive inventory of activated parts was calculated by ORIGEN2, and the effects of bum-up, operation mode and power change on the radioactive inventory for activated parts were analyzed. The results indicated that the radioactive inventory grew with the increasing of burn-up, and when the actual operation time was longer than the effective operation time, the increasing rate of nuclide activity approximated the burn-up increasing; Radioactive inventory of activated parts was influenced directly by the operation modes of the nuclear power unit, and under same reactor load, operation power and bum-up, the radioactive inventory for non-continuous operation mode is less than that for the continuous operation mode. Effects of operation modes on radioactive inventory reversed with half life of nuclides. Under same bum-up and longer operation time, the effect of operation power change on the radioactive inventory is not obvious, (authors)
Directory of Open Access Journals (Sweden)
T.P. Peixoto
2008-12-01
Full Text Available Foram utilizados 20 cães de raças e idades variadas, machos e fêmeas, portadores de catarata e não diabéticos, os quais foram submetidos ao exame oftálmico. Posteriormente, realizaram-se mensurações oculares empregando-se um ecobiômetro ultra-sônico (ultra-sonografia modo-A para o cálculo do poder dióptrico da lente intra-ocular por meio da fórmula SRK/T. O comprimento axial médio foi de 19,94±1,12mm. Todos os animais foram submetidos à facoemulsificação extracapsular. A lente calculada foi implantada no transoperatório da cirurgia de catarata, obtendo-se média de 37,33±3,05D. A avaliação pós-cirúrgica do erro refracional aos 60 dias de pós-operatório, pela retinoscopia, com a utilização da esquiascopia, foi de 5,57±1,59D. A fórmula SRK/T não ofereceu bons resultados.Twenty males and females non-diabetic dogs of different breeds and ages underwent ophthalmic examination because they presented catarats. Ocular measurements were performed by echobiometry (A-scan ultrasound for intraocular lens power calculation using the SRK/T formula. The obtained mean axial length was 19.94±1.12mm. All animals were submitted to extracapsular phacoemulsification; the mean intraocular lens power implanted was 37.33±3.05. At 60 days postoperative, the refractional error assessed via retinoscopy was 5.57±1.59 D. The SRK/T formula did not offer good results.
International Nuclear Information System (INIS)
Dawahra, S.; Khattab, K.
2011-01-01
Highlights: → The MCNP4C code was used to calculate the power distribution in 3-D geometry in the MNSR reactor. → The maximum power of the individual rod was found in the fuel ring number 2 and was found to be 105 W. → The minimum power was found in the fuel ring number 9 and was 79.9 W. → The total power in the total fuel rods was 30.9 kW. - Abstract: The Monte Carlo method, using the MCNP4C code, was used in this paper to calculate the power distribution in 3-D geometry in the fuel rods of the Syrian Miniature Neutron Source Reactor (MNSR). To normalize the MCNP4C result to the steady state nominal thermal power, the appropriate scaling factor was defined to calculate the power distribution precisely. The maximum power of the individual rod was found in the fuel ring number 2 and was found to be 105 W. The minimum power was found in the fuel ring number 9 and was 79.9 W. The total power in the total fuel rods was 30.9 kW. This result agrees very well with nominal power reported in the reactor safety analysis report which equals 30 kW. Finally, the peak power factors, which are defined as the ratios between the maximum to the average and the maximum to the minimum powers were calculated to be 1.18 and 1.31 respectively.
International Nuclear Information System (INIS)
Mochamad Nasrullah; Sudi Arianto
2005-01-01
Nuclear power plant as one alternative power plant for Indonesia is expected to attract interest of investors to invest in electricity sector. Calculation of investment cost and electricity tariff is a nearly necessary Information needed by investors. Spread sheet calculations on construction cost including Interest During Construction and escalation as well as financial viability are implemented. Result of the study show that overnight cost before escalation is US $ 2.682.865.200,- and after IDC and escalation it becomes US $ 3.795.712.088 or 1.807,5 US$/k We. Levelized Tariff is at around 4,57 cents/kWh. Levelized Tariff is 3,5 cents/kWh not feasible to the project of because all financial parameter show negative value. The project is financially feasible if calculated levelized tariff within arrange of 4,0 cents/kWh-5,5 cents/kWh. The most profitable tariff for investor is within arrange of 4,87 cents/kWh - 5,11 cents/kWh. (author)
Directory of Open Access Journals (Sweden)
Anneé Miranda Carracedo
2012-12-01
Full Text Available Objetivo: personalizar las constantes A, factor cirujano y profundidad de la cámara anterior para las fórmulas de cálculo de la lente intraocular en la cirugía de catarata en el Instituto Cubano de Oftalmología "Ramón Pando Ferrer" de mayo de 2007 a enero de 2011. Métodos: se realizó un estudio descriptivo retrospectivo donde se estudiaron las constantes A, factor cirujano y profundidad de la cámara anterior. También se evaluó la longitud axial preoperatoria por IOL Master, la mejor agudeza visual sin corrección, el componente esférico esperado, el componente esférico obtenido y los resultados refractivos. Resultados: las constantes optimizadas por interferometría de coherencia parcial son diferentes a las propuestas por los fabricantes de las lentes intraoculares. Estas constantes personalizadas para cada cirujano no mostraron diferencias significativas. Las constantes optimizadas según las longitudes axiales, tienen diferencias significativas en los 3 grupos de estudio. La diferencia entre la lente intraocular implantada y la propuesta con las nuevas constantes resultó menor de 1 D de error en 83,1 % de los pacientes. El 75,4 % quedó bien corregido en relación con la diferencia entre la refracción esperada y la obtenida. Conclusiones: las constantes optimizadas por interferometría de coherencia parcial resultan más elevadas que las propuestas por el fabricante. La optimización de estas en el cálculo de la lente permite, de acuerdo a las características individuales de cada ojo (longitud axial, usar la fórmula adecuada e incrementa la predictibilidad de los resultados refractivos posoperatorios.Objective: to personalize the A, surgeon factor and anterior chamber depth constants for intraocular lens calculation formulas in the cataract surgery at the “Ramón Pando Ferrer” Cuban Ophthalmological Institute from May 2007 to January 2011. Method: a retrospective and descriptive study was made to study the A constant
Calculation of pellet radial power distributions with a Monte Carlo burnup code
International Nuclear Information System (INIS)
Suzuki, Motomu; Yamamoto, Toru; Nakata, Tetsuo
2010-01-01
The Japan Nuclear Energy Safety Organization (JNES) has been working on an irradiation test program of high-burnup MOX fuel at Halden Boiling Water Reactor (HBWR). MOX and UO 2 fuel rods had been irradiated up to about 64 GWd/t (rod avg.) as a Japanese utilities research program (1st phase), and using those fuel rods, in-situ measurement of fuel pellet centerline temperature was done during the 2nd phase of irradiation as the JNES test program. As part of analysis of the temperature data, power distributions in a pellet radial direction were analyzed by using a Monte Carlo burnup code MVP-BURN. In addition, the calculated results of deterministic burnup codes SRAC and PLUTON for the same problem were compared with those of MVP-BURN to evaluate their accuracy. Burnup calculations with an assembly model were performed by using MVP-BURN and those with a pin cell model by using SRAC and PLUTON. The cell pitch and, therefore, fuel to moderator ratio in the pin cell calculation was determined from the comparison of neutron energy spectra with those of MVP-BURN. The fuel pellet radial distributions of burnup and fission reaction rates at the end of the 1st phase irradiation were compared between the three codes. The MVP-BURN calculation results show a large peaking in the burnup and fission rates in the pellet outer region for the UO 2 and MOX pellets. The SRAC calculations give very close results to those of the MVP-BURN. On the other hand, the PLUTON calculations show larger burnup for the UO 2 and lower burnup for the MOX pellets in the pellet outer region than those of MVP-BURN, which lead to larger fission rates for the UO 2 and lower fission rates for the MOX pellets, respectively. (author)
Power distribution and fuel depletion calculation for a PWR, using LEOPARD and CITATION codes
International Nuclear Information System (INIS)
Batista, J.L.
1982-01-01
By modifying LEOPARD a new program, LEOCIT, has been developed in which additional subroutines prepare cross-section libraries in 1, 2 or 4 energy groups and subsequently record these on disc or tape in a format appropriate for direct input to the CITATION code. Use of LEOCIT in conjunction with CITATION is demonstrated by simulating the first depletion cycle of Angra Unit 1. In these calculations two energy groups are used in 1/4, X - Y geometry to give the soluble boron curve, the fuel depletion and the point to point power distribution in Angra 1. Finally relevant results obtained here are compared with those published by Westinghouse, CNEN and Furnas and recommendations are made to improve the system of neutronic calculation developed in this work. (Author) [pt
Fuel consumption and greenhouse gas calculator for diesel and biodiesel-powered vehicles
Energy Technology Data Exchange (ETDEWEB)
NONE
2008-07-01
Factors that influence fuel consumption include environmental conditions, maintenance, poor driving techniques, and driving speed. Developed by Natural Resources Canada, the SmartDriver training programs were designed to help fleet managers, drivers, and instructors to learn methods of improving fuel economy. This fuel consumption and greenhouse gas (GHG) calculator for diesel and biodiesel-powered vehicles provides drivers with a method of calculating fuel consumption rates when driving. It includes a log-book in which to record odometer readings and a slide-rule in which to determine the litres of fuel used during a trip. The scale showed the number of kg of GHGs produced by burning a particular amount of fuel for both biodiesel and diesel fuels. 1 fig.
International Nuclear Information System (INIS)
Zhang, Xiaoguang; Varga, Kalman; Pantelides, Sokrates T
2007-01-01
Band-theoretic methods with periodically repeated supercells have been a powerful approach for ground-state electronic structure calculations, but have not so far been adapted for quantum transport problems with open boundary conditions. Here we introduce a generalized Bloch theorem for complex periodic potentials and use a transfer-matrix formulation to cast the transmission probability in a scattering problem with open boundary conditions in terms of the complex wave vectors of a periodic system with absorbing layers, allowing a band technique for quantum transport calculations. The accuracy and utility of the method is demonstrated by the model problems of the transmission of an electron over a square barrier and the scattering of a phonon in an inhomogeneous nanowire. Application to the resistance of a twin boundary in nanocrystalline copper yields excellent agreement with recent experimental data
Branca, Mario
2013-01-01
Why does a lens magnify? Why does it shrink objects? Why does this happen? The activities that we propose here are useful in helping us to understand how lenses work, and they show that the same lens can have different magnification capabilities. A converging lens can also act as a diverging lens. (Contains 4 figures.)
International Nuclear Information System (INIS)
Alvarez, M.C.; Garzon, L.
1990-01-01
In this paper a practical dispersion model is presented, which permits to calculate, in Spain, the concentration of natural radionuclides released to the atmosphere from coal power plants. To apply the model it is necessary to know the following data: emission rates, dry deposition velocity, scavenging coefficient, mixing layer height, together with climatological frequency data relating to wind speed and wind direction (to determinate trajectories from a given source) in the areas examined. Meteorological data can be obtained from meteorological stations across Spain. (Author)
International Nuclear Information System (INIS)
Kophazi, J.; Czifrus, Sz.; Feher, S.; Por, G.
2001-01-01
The paper describes the measurement of the delayed signal of a Rh emitter Self Powered Neutron Detector (SPND) separately from other signal components originating from (n-gamma-e), (background gamma-e) and other effects. In order to separate the delayed signal, the detector was removed from the reactor core and placed to an adequately distant location during the measurement, where the radiation from the core was negligible. The experiment was carried out on the 100kW light water tank-type reactor of Technical University of Budapest and the results of the measurement were compared with the results of Monte Carlo calculations.(author)
Application of ultrasonic inspection data in strength calculations for nuclear power plant equipment
International Nuclear Information System (INIS)
Ovchinnikov, A.V.; Rivkin, E.Yu.; Vasilchenko, G.S.; Zvezdin, Yu.I.
1991-01-01
Several kinds of test specimens were produced with three types of defects of defined sizes and positions in the particular localities of weld joints. Such specimens have been used for defect parameter characterization by ultrasonic testing. The principles for schematization of such defects and the formulae for the stress intensity factor calculations for elliptical and semielliptical cracks have been worked out. Methods for defining the sizes of defect which are acceptable have been designed for use for use on operational nuclear power plant equipment and take account of the mutual effects of the force, thermal and residual stresses. The method can be used in the brittle, transitional and tough material state. (author)
CPU time reduction strategies for the Lambda modes calculation of a nuclear power reactor
Energy Technology Data Exchange (ETDEWEB)
Vidal, V.; Garayoa, J.; Hernandez, V. [Universidad Politecnica de Valencia (Spain). Dept. de Sistemas Informaticos y Computacion; Navarro, J.; Verdu, G.; Munoz-Cobo, J.L. [Universidad Politecnica de Valencia (Spain). Dept. de Ingenieria Quimica y Nuclear; Ginestar, D. [Universidad Politecnica de Valencia (Spain). Dept. de Matematica Aplicada
1997-12-01
In this paper, we present two strategies to reduce the CPU time spent in the lambda modes calculation for a realistic nuclear power reactor.The discretization of the multigroup neutron diffusion equation has been made using a nodal collocation method, solving the associated eigenvalue problem with two different techniques: the Subspace Iteration Method and Arnoldi`s Method. CPU time reduction is based on a coarse grain parallelization approach together with a multistep algorithm to initialize adequately the solution. (author). 9 refs., 6 tabs.
Approximate techniques for calculating gamma ray dose rates in nuclear power plants
International Nuclear Information System (INIS)
Lahti, G.P.
1986-01-01
Although today's computers have made three-dimensional discrete ordinates transport codes a virtual reality, there is still a need for approximate techniques for estimating radiation environments. This paper discusses techniques for calculating gamma ray dose rates in nuclear power plants where Compton scattering is the dominant attenuation mechanism. The buildup factor method is reviewed; its use and misuse are discussed. Several useful rules-of-thumb are developed. The paper emphasizes the need for understanding the fundamental physics and draws heavily on the old, classic references
Improvement of Power Flow Calculation with Optimization Factor Based on Current Injection Method
Directory of Open Access Journals (Sweden)
Lei Wang
2014-01-01
Full Text Available This paper presents an improvement in power flow calculation based on current injection method by introducing optimization factor. In the method proposed by this paper, the PQ buses are represented by current mismatches while the PV buses are represented by power mismatches. It is different from the representations in conventional current injection power flow equations. By using the combined power and current injection mismatches method, the number of the equations required can be decreased to only one for each PV bus. The optimization factor is used to improve the iteration process and to ensure the effectiveness of the improved method proposed when the system is ill-conditioned. To verify the effectiveness of the method, the IEEE test systems are tested by conventional current injection method and the improved method proposed separately. Then the results are compared. The comparisons show that the optimization factor improves the convergence character effectively, especially that when the system is at high loading level and R/X ratio, the iteration number is one or two times less than the conventional current injection method. When the overloading condition of the system is serious, the iteration number in this paper appears 4 times less than the conventional current injection method.
A power spectrum approach to tally convergence in Monte Carlo criticality calculation
International Nuclear Information System (INIS)
Ueki, Taro
2017-01-01
In Monte Carlo criticality calculation, confidence interval estimation is based on the central limit theorem (CLT) for a series of tallies from generations in equilibrium. A fundamental assertion resulting from CLT is the convergence in distribution (CID) of the interpolated standardized time series (ISTS) of tallies. In this work, the spectral analysis of ISTS has been conducted in order to assess the convergence of tallies in terms of CID. Numerical results obtained indicate that the power spectrum of ISTS is equal to the theoretically predicted power spectrum of Brownian motion for tallies of effective neutron multiplication factor; on the other hand, the power spectrum of ISTS of a strongly correlated series of tallies from local powers fluctuates wildly while maintaining the spectral form of fractional Brownian motion. The latter result is the evidence of a case where a series of tallies are away from CID, while the spectral form supports normality assumption on the sample mean. It is also demonstrated that one can make the unbiased estimation of the standard deviation of sample mean well before CID occurs. (author)
Nodal methods for calculating nuclear reactor transients, control rod patterns, and fuel pin powers
International Nuclear Information System (INIS)
Cho, Byungoh.
1990-01-01
Nodal methods which are used to calculate reactor transients, control rod patterns, and fuel pin powers are investigated. The 3-D nodal code, STORM, has been modified to perform these calculations. Several numerical examples lead to the following conclusions: (1) By employing a thermal leakage-to-absorption ratio (TLAR) approximation for the spatial shape of the thermal fluxes for the 3-D Langenbuch-Maurer-Werner (LMW) and the superprompt critical transient problems, the convergence of the conventional two-group scheme is accelerated. (2) By employing the steepest-ascent hill climbing search with heuristic strategies, Optimum Control Rod Pattern Searcher (OCRPS) is developed for solving control rod positioning problem in BWRs. Using the method of approximation programming the objective function and the nuclear and thermal-hydraulic constraints are modified as heuristic functions that guide the search. The test calculations have demonstrated that, for the first cycle of the Edwin Hatch Unit number-sign 2 reactor, OCRPS shows excellent performance for finding a series of optimum control rod patterns for six burnup steps during the operating cycle. (3) For the modified two-dimensional EPRI-9R problem, the least square second-order polynomial flux expansion method was demonstrated to be computationally about 30 times faster than a fine-mesh finite difference calculation in order to achieve comparable accuracy for pin powers. The basic assumption of this method is that the reconstructed flux can be expressed as a product of an assembly form function and a second-order polynomial function
21 CFR 886.1405 - Ophthalmic trial lens set.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic trial lens set. 886.1405 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1405 Ophthalmic trial lens set. (a) Identification. An ophthalmic trial lens set is a device that is a set of lenses of various dioptric powers...
Energy Technology Data Exchange (ETDEWEB)
Kim, Seung Jun [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Buechler, Cynthia Eileen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-07-17
The current study aims to predict the steady state power of a generic solution vessel and to develop a corresponding heat transfer coefficient correlation for a Moly99 production facility by conducting a fully coupled multi-physics simulation. A prediction of steady state power for the current application is inherently interconnected between thermal hydraulic characteristics (i.e. Multiphase computational fluid dynamics solved by ANSYS-Fluent 17.2) and the corresponding neutronic behavior (i.e. particle transport solved by MCNP6.2) in the solution vessel. Thus, the development of a coupling methodology is vital to understand the system behavior at a variety of system design and postulated operating scenarios. In this study, we report on the k-effective (keff) calculation for the baseline solution vessel configuration with a selected solution concentration using MCNP K-code modeling. The associated correlation of thermal properties (e.g. density, viscosity, thermal conductivity, specific heat) at the selected solution concentration are developed based on existing experimental measurements in the open literature. The numerical coupling methodology between multiphase CFD and MCNP is successfully demonstrated, and the detailed coupling procedure is documented. In addition, improved coupling methods capturing realistic physics in the solution vessel thermal-neutronic dynamics are proposed and tested further (i.e. dynamic height adjustment, mull-cell approach). As a key outcome of the current study, a multi-physics coupling methodology between MCFD and MCNP is demonstrated and tested for four different operating conditions. Those different operating conditions are determined based on the neutron source strength at a fixed geometry condition. The steady state powers for the generic solution vessel at various operating conditions are reported, and a generalized correlation of the heat transfer coefficient for the current application is discussed. The assessment of multi
Determining spherical lens correction for astronaut training underwater.
Porter, Jason; Gibson, C Robert; Strauss, Samuel
2011-09-01
To develop a model that will accurately predict the distance spherical lens correction needed to be worn by National Aeronautics and Space Administration astronauts while training underwater. The replica space suit's helmet contains curved visors that induce refractive power when submersed in water. Anterior surface powers and thicknesses were measured for the helmet's protective and inside visors. The impact of each visor on the helmet's refractive power in water was analyzed using thick lens calculations and Zemax optical design software. Using geometrical optics approximations, a model was developed to determine the optimal distance spherical power needed to be worn underwater based on the helmet's total induced spherical power underwater and the astronaut's manifest spectacle plane correction in air. The validity of the model was tested using data from both eyes of 10 astronauts who trained underwater. The helmet's visors induced a total power of -2.737 D when placed underwater. The required underwater spherical correction (FW) was linearly related to the spectacle plane spherical correction in air (FAir): FW = FAir + 2.356 D. The mean magnitude of the difference between the actual correction worn underwater and the calculated underwater correction was 0.20 ± 0.11 D. The actual and calculated values were highly correlated (r = 0.971) with 70% of eyes having a difference in magnitude of astronauts. The model accurately predicts the actual values worn underwater and can be applied (more generally) to determine a suitable spectacle lens correction to be worn behind other types of masks when submerged underwater.
Development of Internet algorithms and some calculations of power plant COP
Ustjuzhanin, E. E.; Ochkov, V. F.; Znamensky, V. E.
2017-11-01
sharing: a) SW that is used to design power plants, for an example, Code - GTP_1(Z,R,Y) and b) client functions those are aimed to determine R properties of the working fluid at fixed points of the thermodynamic cycle. The program let us calculate energy criteria, Z, including the internal coefficient of performance (COP) for a power plant. We have discussed OI resources, among them OI resource that includes Code - GTP_1(Z,R,Y) and connected with a complex power plant included: i) several gas turbines, i) several compressors etc.
Aero-acoustics noise assessment for Wind-Lens turbine
International Nuclear Information System (INIS)
Hashem, I.; Mohamed, M.H.; Hafiz, A.A.
2017-01-01
This paper introduces an aero-acoustic computational study that investigates the noise caused by one of the most promising wind energy conversion concepts, namely the 'Wind-Lens' technology. The hybrid method - where the flow field and acoustic field are solved separately, was deemed to be an appropriate tool to compute this study. The need to investigate this phenomenon increased gradually, since the feasibility of utilizing Wind-Lens turbine within densely populated cities and urban areas depends largely on their noise generation. Ffowcs Williams-Hawkings (FW-H) equation and its integral solution are used to predict the noise radiating to the farfield. CFD Simulations of transient three-dimensional flow field using (URANS) unsteady Reynolds-averaged Navier-Stokes equations are computed to acquire the acoustic sources location and sound intensity. Then, the noise propagates from the before-mentioned sources to pre-defined virtual microphones positioned in different locations. ANSYS-FLUENT is used to calculate the flow field on and around such turbines which is required for the FW-H code. Some effective parameters are investigated such as Wind-Lens shape, brim height and tip speed ratio. Comparison of the noise emitted from the bare wind turbine and different types of Wind-Lens turbine reveals that, the Wind-Lens generates higher noise intensity. - Highlights: • Aero-acoustic noise generated by wind turbines are one of the major challenges. • Noise from wind turbine equipped with a brimmed diffuser is investigated. • A computational aero-acoustic study using the hybrid method is introduced. • Effective parameters are studied such Wind-Lens shape, brim height and speed ratio. • The optimal shape has a moderate power coefficient and the less noise generation.
Energy Technology Data Exchange (ETDEWEB)
Ödén, Jakob [Department of Medical Physics, Karolinska University Hospital, Stockholm SE-17176, Sweden and Department of Medical Radiation Physics, Stockholm University and Karolinska Institutet, Stockholm SE-17176 (Sweden); Zimmerman, Jens; Nowik, Patrik; Poludniowski, Gavin, E-mail: gavin.poludniowski@karolinska.se [Department of Medical Physics, Karolinska University Hospital, Stockholm SE-17176 (Sweden); Bujila, Robert [Department of Medical Physics, Karolinska University Hospital, Stockholm SE-17176, Sweden and Department of Physics, Royal Institute of Technology, Stockholm SE-10691 (Sweden)
2015-09-15
Purpose: The quantitative effects of assumptions made in the calculation of stopping-power ratios (SPRs) are investigated, for stoichiometric CT calibration in proton therapy. The assumptions investigated include the use of the Bethe formula without correction terms, Bragg additivity, the choice of I-value for water, and the data source for elemental I-values. Methods: The predictions of the Bethe formula for SPR (no correction terms) were validated against more sophisticated calculations using the SRIM software package for 72 human tissues. A stoichiometric calibration was then performed at our hospital. SPR was calculated for the human tissues using either the assumption of simple Bragg additivity or the Seltzer-Berger rule (as used in ICRU Reports 37 and 49). In each case, the calculation was performed twice: First, by assuming the I-value of water was an experimentally based value of 78 eV (value proposed in Errata and Addenda for ICRU Report 73) and second, by recalculating the I-value theoretically. The discrepancy between predictions using ICRU elemental I-values and the commonly used tables of Janni was also investigated. Results: Errors due to neglecting the correction terms to the Bethe formula were calculated at less than 0.1% for biological tissues. Discrepancies greater than 1%, however, were estimated due to departures from simple Bragg additivity when a fixed I-value for water was imposed. When the I-value for water was calculated in a consistent manner to that for tissue, this disagreement was substantially reduced. The difference between SPR predictions when using Janni’s or ICRU tables for I-values was up to 1.6%. Experimental data used for materials of relevance to proton therapy suggest that the ICRU-derived values provide somewhat more accurate results (root-mean-square-error: 0.8% versus 1.6%). Conclusions: The conclusions from this study are that (1) the Bethe formula can be safely used for SPR calculations without correction terms; (2
International Nuclear Information System (INIS)
Ödén, Jakob; Zimmerman, Jens; Nowik, Patrik; Poludniowski, Gavin; Bujila, Robert
2015-01-01
Purpose: The quantitative effects of assumptions made in the calculation of stopping-power ratios (SPRs) are investigated, for stoichiometric CT calibration in proton therapy. The assumptions investigated include the use of the Bethe formula without correction terms, Bragg additivity, the choice of I-value for water, and the data source for elemental I-values. Methods: The predictions of the Bethe formula for SPR (no correction terms) were validated against more sophisticated calculations using the SRIM software package for 72 human tissues. A stoichiometric calibration was then performed at our hospital. SPR was calculated for the human tissues using either the assumption of simple Bragg additivity or the Seltzer-Berger rule (as used in ICRU Reports 37 and 49). In each case, the calculation was performed twice: First, by assuming the I-value of water was an experimentally based value of 78 eV (value proposed in Errata and Addenda for ICRU Report 73) and second, by recalculating the I-value theoretically. The discrepancy between predictions using ICRU elemental I-values and the commonly used tables of Janni was also investigated. Results: Errors due to neglecting the correction terms to the Bethe formula were calculated at less than 0.1% for biological tissues. Discrepancies greater than 1%, however, were estimated due to departures from simple Bragg additivity when a fixed I-value for water was imposed. When the I-value for water was calculated in a consistent manner to that for tissue, this disagreement was substantially reduced. The difference between SPR predictions when using Janni’s or ICRU tables for I-values was up to 1.6%. Experimental data used for materials of relevance to proton therapy suggest that the ICRU-derived values provide somewhat more accurate results (root-mean-square-error: 0.8% versus 1.6%). Conclusions: The conclusions from this study are that (1) the Bethe formula can be safely used for SPR calculations without correction terms; (2
Peripheral Defocus of the Monkey Crystalline Lens With Accommodation in a Lens Stretcher
Maceo Heilman, Bianca; Manns, Fabrice; Ruggeri, Marco; Ho, Arthur; Gonzalez, Alex; Rowaan, Cor; Bernal, Andres; Arrieta, Esdras; Parel, Jean-Marie
2018-01-01
Purpose To characterize the peripheral defocus of the monkey crystalline lens and its changes with accommodation. Methods Experiments were performed on 15 lenses from 11 cynomolgus monkey eyes (age: 3.8–12.4 years, postmortem time: 33.5 ± 15.3 hours). The tissue was mounted in a motorized lens stretcher to allow for measurements of the lens in the accommodated (unstretched) and unaccommodated (stretched) states. A custom-built combined laser ray tracing and optical coherence tomography system was used to measure the paraxial on-axis and off-axis lens power for delivery angles ranging from −20° to +20° (in air). For each delivery angle, peripheral defocus was quantified as the difference between paraxial off-axis and on-axis power. The peripheral defocus of the lens was compared in the unstretched and stretched states. Results On average, the paraxial on-axis lens power was 52.0 ± 3.4 D in the unstretched state and 32.5 ± 5.1 D in the stretched state. In both states, the lens power increased with increasing delivery angle. From 0° to +20°, the relative peripheral lens power increased by 10.7 ± 1.4 D in the unstretched state and 7.5 ± 1.6 D in the stretched state. The change in field curvature with accommodation was statistically significant (P lens has greater curvature or relative peripheral power. Conclusions The cynomolgus monkey lens has significant accommodation-dependent curvature of field, which suggests that the lens asserts a significant contribution to the peripheral optical performance of the eye that also varies with the state of accommodation.
Impact of Uncertainty on Calculations for Recovery from Loss of Offsite Power
International Nuclear Information System (INIS)
Kelly, Dana L.
2010-01-01
Uncertainty, both aleatory and epistemic, can have a significant impact on estimated probabilities of recovering from loss of offsite power within a specified time window, and such probabilities are an input to risk-informed decisions as to the significance of inspection findings in the U.S. Nuclear Regulatory Commission's Reactor Oversight Process. In particular, the choice of aleatory model for offsite power recovery time can have a significant impact on the estimated nonrecovery probability, especially if epistemic uncertainty regarding parameters in the aleatory model is accounted for properly. In past and current analyses, such uncertainty has largely been ignored. This paper examines the impact of both aleatory and epistemic uncertainty on the results, using modern open-source Bayesian inference software, which implements Markov chain Monte Carlo sampling. It includes examples of time-dependent convolution calculations to show the impact that uncertainty can have on this increasingly frequent type of calculation, also. The results show that the 'point estimate' result, which is an input to risk-informed decisions, can easily be uncertain by a factor of 10 if both aleatory and epistemic uncertainties are considered. The paper also illustrates the use of Bayesian model selection criteria to aid in the choice of aleatory model.
International Nuclear Information System (INIS)
Licks, Leticia A.; Pires, Marcal
2008-01-01
This work intends to evaluate the emissions of carbon dioxide (CO 2 ) emitted by the burning of fossil coal in Brazil. So, a detailed methodology is proposed for calculation of CO 2 emissions from the carbon emission coefficients specific for the Brazilian carbons. Also, the using of secondary fuels (fuel oil and diesel oil) were considered and the power generation for the calculation of emissions and efficiencies of each power plant as well. The obtained results indicate carbon emissions for the year 2002 approximately of the order of 1,794 Gg, with 20% less than the obtained by the official methodology (MCT). Such differences are related to the non consideration of the humidity containment of the coals as well as the using of generic coefficients not adapted to the Brazilian coals. The obtained results indicate the necessity to review the emission inventories and the modernization of the burning systems aiming the increase the efficiency and reduction of the CO 2 and other pollutants, as an alternative for maintaining the sustainable form of using the fossil coal in the country
A case study and critical assessment in calculating power usage effectiveness for a data centre
International Nuclear Information System (INIS)
Brady, Gemma A.; Kapur, Nikil; Summers, Jonathan L.; Thompson, Harvey M.
2013-01-01
Highlights: • A case study PUE calculation is carried out on a data centre by using open source specifications. • The PUE metric does not drive improvements in the efficiencies of IT processes. • The PUE does not fairly represent energy use; an increase in IT load can lead to a decrease in the PUE. • Once a low PUE is achieved, power supply efficiency and IT load have the greatest impact on its value. - Abstract: Metrics commonly used to assess the energy efficiency of data centres are analysed through performing and critiquing a case study calculation of energy efficiency. Specifically, the metric Power Usage Effectiveness (PUE), which has become a de facto standard within the data centre industry, will be assessed. This is achieved by using open source specifications for a data centre in Prineville, Oregon, USA provided by the Open Compute Project launched by the social networking company Facebook. The usefulness of the PUE metric to the IT industry is critically assessed and it is found that whilst it is important for encouraging lower energy consumption in data centres, it does not represent an unambiguous measure of energy efficiency
Tokamak plasma power balance calculation code (TPC code) outline and operation manual
International Nuclear Information System (INIS)
Fujieda, Hirobumi; Murakami, Yoshiki; Sugihara, Masayoshi.
1992-11-01
This report is a detailed description on the TPC code, that calculates the power balance of a tokamak plasma according to the ITER guidelines. The TPC code works on a personal computer (Macintosh or J-3100/ IBM-PC). Using input data such as the plasma shape, toroidal magnetic field, plasma current, electron temperature, electron density, impurities and heating power, TPC code can determine the operation point of the fusion reactor (Ion temperature is assumed to be equal to the electron temperature). Supplied flux (Volt · sec) and burn time are also estimated by coil design parameters. Calculated energy confinement time is compared with various L-mode scaling laws and the confinement enhancement factor (H-factor) is evaluated. Divertor heat load is predicted by using simple scaling models (constant-χ, Bohm-type-χ and JT-60U empirical scaling models). Frequently used data can be stored in a 'device file' and used as the default values. TPC code can generate 2-D mesh data and the POPCON plot is drawn by a contour line plotting program (CONPLT). The operation manual about CONPLT code is also described. (author)
Nemeth, Gabor; Nagy, Attila; Berta, Andras; Modis, Laszlo
2012-09-01
Comparison of postoperative refraction results using ultrasound biometry with closed immersion shell and optical biometry. Three hundred and sixty-four eyes of 306 patients (age: 70.6 ± 12.8 years) underwent cataract surgery where intraocular lenses calculated by SRK/T formula were implanted. In 159 cases immersion ultrasonic biometry, in 205 eyes optical biometry was used. Differences between predicted and actual postoperative refractions were calculated both prior to and after optimization with the SRK/T formula, after which we analysed the similar data in the case of Holladay, Haigis, and Hoffer-Q formulas. Mean absolute error (MAE) and the percentage rate of patients within ±0.5 and ±1.0 D difference in the predicted error were calculated with these four formulas. MAE was 0.5-0.7 D in cases of both methods with SRK/T, Holladay, and Hoffer-Q formula, but higher with Haigis formula. With no optimization, 60-65 % of the patients were under 0.5 D error in the immersion group (except for Haigis formula). Using the optical method, this value was slightly higher (62-67 %), however, in this case, Haigis formula also did not perform so well (45 %). Refraction results significantly improved with Holladay, Hoffer-Q, and Haigis formulas in both groups. The rate of patients under 0.5 D error increased to 65 % by the immersion technique, and up to 80 % by the optical one. According to our results, optical biometry offers only slightly better outcomes compared to those of immersion shell with no optimized formulas. However, in case of new generation formulas with both methods, the optimization of IOL-constants give significantly better results.
International Nuclear Information System (INIS)
Molina, G.
1985-01-01
Utilization of nuclear energy to produce or generate electricity is a growing practice in the world, since it represent an economic and safe option to replace fossil fuels. During operation of nuclear power plants, radioactive materials are produced. A small fraction of these material are released to environment in the form of liquid or gaseous effluents. Estimation of radiation doses causing by effluents release has three purposes. During design phase of a nuclear station it is useful to adapt the wastes treatment systems to acceptable limits. During licensing phase, the regulator organism verifies the design of nuclear station effectuating estimation of doses. Finally, during operation of a nuclear station, before every unload of radioactive effluents, radiation doses should be evaluate in order to fulfill technical specifications, which limit the release of radioactive materials to environment. 1. To perform calculations of individual doses due to liquid radioactive effluents unload in units 1 and 2 of Laguna Verde nuclear power plant (In licensing phase). 2. To perform a parametric study of the effect of unload recirculation over individual dose, since recirculation has two principal effects: thermodynamical effects in nuclear station and radioactivity concentration, the last can affect the fullfilment of dose limits. 3. To perform the calculation of collective doses causes by unloads of liquid effluents within a radius of 80 Kms. of nuclear station caused by unload of liquid radioactive effluents during normal operation of nuclear power plant and does not include doses caused during accident conditions. In Mexico the organism in charge of regulation of peaceful uses of nuclear energy is Comision Nacional de Seguridad Nuclear y Salvaguardias (CNSNS) and for Laguna Verde licensing, the regulations of country who manufactured the reactor was adopted, it is to say United States of America. In Appendix 'C' units used along this work are explained. Unless another
International Nuclear Information System (INIS)
Martinez, G.; Sancho, M.; Garcia-Galan, J.C.
1987-01-01
A powerful version of the charge-density method is applied to the study of a combined objective and emission lens, suitable for highly localized analysis of a flat sample surface. This lens can extract secondary ions of equal or opposite polarity to that of the primary particles. A computer simulation of the ion trajectories for both modes is made. The behaviour for different values of the geometric parameters and polarizations is analyzed and useful data for design such as primary beam demagnification and secondary image position are given. (author) 4 refs
Water hammer calculation and analysis in main feedwater system of PWR nuclear power plants
International Nuclear Information System (INIS)
Wang Xin; Han Weishi
2010-01-01
The main feedwater system of a nuclear power plant is an important part in ensuring the cooling of the steam generator. Moreover, it is the main pipe section where water hammers frequently occur. Studying the regular patterns of water hammers to the main feedwater system is significant to the stable operation of the system. The paper focuses on the study of water hammers through Flowmaster's transient calculating function to establish a mathematical model with boundary conditions such as a feedwater pump, control valves, etc.; calculation of the water hammers pressure when feedwater pumps and control valves shut down; exporting the instantaneous change in solution of pressure. Combined with engineering practical examples, the conclusions verify the viability of calculating the water hammers pressure through Flowmaster's transient function, increasing the periods of closure of control valves and feedwater pumps control water hammers effectively, changing the intervals of closing signals to feedwater pumps and control valves to relieve hydraulic impact. This could be a guideline for practical engineering design and system optimization. (authors)
Fundamental damper power calculation of the 56 MHz SRF cavity for RHIC
International Nuclear Information System (INIS)
Wu, Q.; Bellavia, S.; Ben-Zvi, I.; Grau, M.; Miglionico, G.; Pai, C.
2011-01-01
At each injection period during RHIC's operation, the beam's frequency sweeps across a wide range, and some of its harmonics will cross the frequency of the 56MHz SRF cavity. To avoid excitation of the cavity at these times, we designed a fundamental damper for the quarter-wave resonator to damp the cavity heavily. The power extracted by the fundamental damper should correspond to the power handling ability of the system at all stages. In this paper, we discuss the power output from the fundamental damper when it is fully extracted, inserted, and any intermediate point. A Fundamental Damper (FD) will greatly reduce the cavity's Q factor to ∼300 during the acceleration phase of the beam. However, when the beam is at store and the FD is removed, the cavity is excited by both the yellow and the blue beams at 2 x 0.3A to attain the required 2MV voltage across its gap. The cavity then is operated to increase the luminosity of the RHIC experiments. Table 1 lists the parameters of the FD. Figure 1 shows the configuration of the FD fully inserted into the 56MHz SRF cavity; this complete insertion is defined as the start location (0cm) of FD simulation, an assumption we make throughout this paper. The power consumed by the cavity while maintaining the beam's energy and its orbit is compensated by the 28MHz accelerating cavities in the storage ring. The power dissipation of the external load is dynamic with respect to the position of the FD during its extraction. As a function of the external Q and the EM field in the cavity, the power should peak with the FD at a certain vertical location. Our calculation of the power extracted is detailed in the following sections. Figure 2 plots the frequency change in the cavity, and the external Q against the changes in position of the FD. The location of the FD is selected carefully such that the frequency will approach the designed working point from the lower side only. The loaded Q of the cavity is 223 when the FD is fully
Automated Fresnel lens tester system
Energy Technology Data Exchange (ETDEWEB)
Phipps, G.S.
1981-07-01
An automated data collection system controlled by a desktop computer has been developed for testing Fresnel concentrators (lenses) intended for solar energy applications. The system maps the two-dimensional irradiance pattern (image) formed in a plane parallel to the lens, whereas the lens and detector assembly track the sun. A point detector silicon diode (0.5-mm-dia active area) measures the irradiance at each point of an operator-defined rectilinear grid of data positions. Comparison with a second detector measuring solar insolation levels results in solar concentration ratios over the image plane. Summation of image plane energies allows calculation of lens efficiencies for various solar cell sizes. Various graphical plots of concentration ratio data help to visualize energy distribution patterns.
BEAVRS full core burnup calculation in hot full power condition by RMC code
International Nuclear Information System (INIS)
Liu, Shichang; Liang, Jingang; Wu, Qu; Guo, JuanJuan; Huang, Shanfang; Tang, Xiao; Li, Zeguang; Wang, Kan
2017-01-01
Highlights: • TMS and thermal scattering interpolation were developed to treat cross sections OTF. • Hybrid coupling system was developed for HFP burnup calculation of BEAVRS benchmark. • Domain decomposition was applied to handle memory problem of full core burnup. • Critical boron concentration with burnup by RMC agrees with the benchmark results. • RMC is capable of multi-physics coupling for simulations of nuclear reactors in HFP. - Abstract: Monte Carlo method can provide high fidelity neutronics analysis of different types of nuclear reactors, owing to its advantages of the flexible geometry modeling and the use of continuous-energy nuclear cross sections. However, nuclear reactors are complex systems with multi-physics interacting and coupling. MC codes can couple with depletion solver and thermal-hydraulics (T/H) codes simultaneously for the “transport-burnup-thermal-hydraulics” coupling calculations. MIT BEAVRS is a typical “transport-burnup-thermal-hydraulics” coupling benchmark. In this paper, RMC was coupled with sub-channel code COBRA, equipped with on-the-fly temperature-dependent cross section treatment and large-scale detailed burnup calculation based on domain decomposition. Then RMC was applied to the full core burnup calculations of BEAVRS benchmark in hot full power (HFP) condition. The numerical tests show that domain decomposition method can achieve the consistent results compared with original version of RMC while enlarging the computational burnup regions. The results of HFP by RMC agree well with the reference values of BEAVRS benchmark and also agree well with those of MC21. This work proves the feasibility and accuracy of RMC in multi-physics coupling and lifecycle simulations of nuclear reactors.
International Nuclear Information System (INIS)
Serov, I.V.; Hoogenboom, J.E.
1994-01-01
Physical quantities can be obtained by utilizing different informational sources. The available information is usually associated with systematic and statistical errors. If the informational sources are utilized simultaneously, then it is possible to obtain posterior estimates of the quantities with better statistical properties than exhibited by any prior estimates. The general technique for confluence of any number possibly dependent informational sources can be developed. Insight into the nature of the informational source allows different types of data associated with the source to be improved. The formulas of the technique are presented and applied to the power distribution determination for research reactor HOR of the Delft University of Technology, employing calculational and experimental data. (authors). 5 refs., 1 tab., 5 figs
Energy Technology Data Exchange (ETDEWEB)
Guerrero, A. F., E-mail: afguerreror@uqvirtual.edu.co [Departamento de Física, Universidad Del Quindío Cra 15 # 12N Armenia, Quindío (Colombia); Mesa, J., E-mail: jmesa@ibb.unesp.br [Instituto de Biociências de Botucatu da UNESP Distrito de Rubião Jr. s/n°, 18618-000, Botucatu, SP (Brazil)
2016-07-07
Because of the behavior that charged particles have when they interact with biological material, proton therapy is shaping the future of radiation therapy in cancer treatment. The planning of radiation therapy is made up of several stages. The first one is the diagnostic image, in which you have an idea of the density, size and type of tumor being treated; to understand this it is important to know how the particles beam interacts with the tissue. In this work, by using de Lindhard formalism and the Y.R. Waghmare model for the charge distribution of the proton, the electronic stopping power (SP) for a proton beam interacting with a liquid water target in the range of proton energies 10{sup 1} eV - 10{sup 10} eV taking into account all the charge states is calculated.
Sensor response time calculation with no stationary signals from a Nuclear Power Plant
International Nuclear Information System (INIS)
Vela, O.; Vallejo, I.
1998-01-01
Protection systems in a Nuclear Power Plant have to response in a specific time fixed by design requirements. This time includes the event detection (sensor delay) and the actuation time system. This time is obtained in refuel simulating the physics event, which trigger the protection system, with an electric signal and measuring the protection system actuation time. Nowadays sensor delay is calculated with noise analysis techniques. The signals are measured in Control Room during the normal operation of the Plant, decreasing both the cost in time and personal radioactive exposure. The noise analysis techniques require stationary signals but normally the data collected are mixed with process signals that are no stationary. This work shows the signals processing to avoid no-stationary components using conventional filters and new wavelets analysis. (Author) 2 refs
Calculation and reduction of the sound emissions of overhead power lines
International Nuclear Information System (INIS)
Straumann, U.
2007-01-01
In this dissertation, Ulrich Straumann of the Swiss Federal Institute of Technology in Zurich, Switzerland, discusses the reduction of sound emissions from overhead power lines. Corona-discharges occur during wet weather or when foggy or icing conditions prevail. Apart from these wide-band crackling noises, low-frequency, tonal emissions also occur. The CONOR (Corona Noise Reduction) project examined these emissions at a frequency of twice the mains frequency and looked for economically feasible solutions to the problems caused by them. The source of these emissions and the mechanisms causing them are discussed. Also, ways of calculating their strength are presented. The effects of varying cable geometry and construction are discussed, as are hydrophilic coatings that could be used to reduce sound emissions.
Single lens to lens duplication: The missing link
Bhatt, Rupal; Jethani, Jitendra; Saluja, Praveen; Bharti, Vinay
2008-01-01
Congenital anomalies of the lens include a wide range from lens coloboma to primary aphakia and doubling of lens. There have been few case reports of double lens; the etiology suggested is metaplastic changes in the surface ectoderm that leads to formation of two lens vesicles and hence resulting in double lens. We report a case with bilobed lens, which raises the possibility of explaining the etiology of double lens.
Yamamura, Hideho; Sato, Ryohei; Iwata, Yoshiharu
Global efforts toward energy conservation, increasing data centers, and the increasing use of IT equipments are leading to a demand in reduced power consumption of equipments, and power efficiency improvement of power supply units is becoming a necessity. MOSFETs are widely used for their low ON-resistances. Power efficiency is designed using time-domain circuit simulators, except for transformer copper-loss, which has frequency dependency which is calculated separately using methods based on skin and proximity effects. As semiconductor technology reduces the ON-resistance of MOSFETs, frequency dependency due to the skin effect or proximity effect is anticipated. In this study, ON-resistance of MOSFETs are measured and frequency dependency is confirmed. Power loss against rectangular current pulse is calculated. The calculation method for transformer copper-loss is expanded to MOSFETs. A frequency function for the resistance model is newly developed and parametric calculation is enabled. Acceleration of calculation is enabled by eliminating summation terms. Using this method, it is shown that the frequency dependent component of the measured MOSFETs increases the dissipation from 11% to 32% at a switching frequency of 100kHz. From above, this paper points out the importance of the frequency dependency of MOSFETs' ON-resistance, provides means of calculating its pulse losses, and improves loss calculation accuracy of SMPSs.
Klee, H. W.; McDowell, M. W.
1986-02-01
The use of the zero power corrector concept has been extended to the design of microscope objectives. Several four and five-element designs are described which include a flat field 10x design of 0.25 numerical aperture and a 40x design of 0.65 numerical aperture.
Calculation methods for simulation and modelling of nuclear power plant accidents
International Nuclear Information System (INIS)
Zurita Centelles, A.
1985-01-01
The study deals with the development of calculation procedures for the determination of transient operating conditions in pressurized water reactors, which present the following characteristics: application of largely analytic methods for the description of primary circuit components; strict modular structure of the program for the easy exchange of component models; applicability of different component models according to the applicable case; large valid ranges of application of the thermodynamic variables of state in the transient models; in case of necessity exchange possibility of slip, pressure drop and heat transmission correlations as well as other functions; application in the dynamic components analyses of the anglo-saxon lumped parameter suitable for the system instrumentation. With these calculation procedures it is possible to analyse the effect of a certain selection of transients - up to reaching turbine tripout and reactor emergency shutdown - in the individual primary circuit components. These transients may be generally classified amongst the heat rejection and heat input modifications in the secondary circuit, in the coolant or in the reactivity balance and power distribution. (orig.) [de
Short-Term Wind Power Forecasting Based on Clustering Pre-Calculated CFD Method
Directory of Open Access Journals (Sweden)
Yimei Wang
2018-04-01
Full Text Available To meet the increasing wind power forecasting (WPF demands of newly built wind farms without historical data, physical WPF methods are widely used. The computational fluid dynamics (CFD pre-calculated flow fields (CPFF-based WPF is a promising physical approach, which can balance well the competing demands of computational efficiency and accuracy. To enhance its adaptability for wind farms in complex terrain, a WPF method combining wind turbine clustering with CPFF is first proposed where the wind turbines in the wind farm are clustered and a forecasting is undertaken for each cluster. K-means, hierarchical agglomerative and spectral analysis methods are used to establish the wind turbine clustering models. The Silhouette Coefficient, Calinski-Harabaz index and within-between index are proposed as criteria to evaluate the effectiveness of the established clustering models. Based on different clustering methods and schemes, various clustering databases are built for clustering pre-calculated CFD (CPCC-based short-term WPF. For the wind farm case studied, clustering evaluation criteria show that hierarchical agglomerative clustering has reasonable results, spectral clustering is better and K-means gives the best performance. The WPF results produced by different clustering databases also prove the effectiveness of the three evaluation criteria in turn. The newly developed CPCC model has a much higher WPF accuracy than the CPFF model without using clustering techniques, both on temporal and spatial scales. The research provides supports for both the development and improvement of short-term physical WPF systems.
Calculation of coal power plant cost on agricultural and material building impact of emission
International Nuclear Information System (INIS)
Mochamad Nasrullah; Wiku Lulus Widodo
2016-01-01
Calculation for externally cost of Coal Power Plant (CPP) is very important. This paper is focus on CPP appear SO 2 impact on agricultural plant and material building. AGRIMAT'S model from International Atomic Energy Agency is model one be used to account environmental damage for air impact because SO 2 emission. Analysis method use Impact Pathways Assessment: Determining characteristic source, Exposure Response Functions (ERF), Impacts and Damage Costs, and Monetary Unit Cost. Result for calculate shows that SO 2 that issued CPP, if value of SO 2 is 19,3 μg/m3, damage cost begins valuably positive. It shows that the land around CPP has decrease prosperity, and it will disadvantage for agricultural plant. On material building, SO 2 resulting damage cost. The increase humidity price therefore damage cost on material building will increase cost. But if concentration SO 2 increase therefore damage cost that is appear on material building decrease. Expected this result can added with external cost on health impact of CPP. External cost was done at developed countries. If it is done at Indonesia, therefore generation cost with fossil as more expensive and will get implication on issue cut back gases greenhouse. On the other side, renewable energy and also alternative energy as nuclear have opportunity at national energy mix system. (author)
Kobayashi, Y; Narazaki, K; Akagi, R; Nakagaki, K; Kawamori, N; Ohta, K
2013-09-01
For achieving accurate and safe measurements of the force and power exerted on a load during resistance exercise, the Smith machine has been used instead of free weights. However, because some Smith machines possess counterweights, the equation for the calculation of force and power in this system should be different from the one used for free weights. The purpose of this investigation was to calculate force and power using an equation derived from a dynamic equation for a Smith machine with counterweights and to determine the differences in force and power calculated using 2 different equations. One equation was established ignoring the effect of the counterweights (Method 1). The other equation was derived from a dynamic equation for a barbell and counterweight system (Method 2). 9 female collegiate judo athletes performed bench throws using a Smith machine with a counterweight at 6 different loading conditions. Barbell displacement was recorded using a linear position transducer. The force and power were subsequently calculated by Methods 1 and 2. The results showed that the mean and peak power and force in Method 1 were significantly lower relative to those of Method 2 under all loading conditions. These results indicate that the mean and peak power and force during bench throwing using a Smith machine with counterweights would be underestimated when the calculations used to determine these parameters do not account for the effect of counterweights. © Georg Thieme Verlag KG Stuttgart · New York.
Actinides record, power calculations and activity for present isotopes in the spent fuel of a BWR
International Nuclear Information System (INIS)
Enriquez C, P.; Ramirez S, J. R.; Lucatero, M. A.
2012-10-01
The administration of spent fuel is one of the more important stages of the nuclear fuel cycle, and this has become a problem of supreme importance in countries that possess nuclear reactors. Due to this in this work, the study on the actinides record and present fission products to the discharge of the irradiated fuel in a light water reactor type BWR is shown, to quantify the power and activity that emit to the discharge and during the cooling time. The analysis was realized on a fuel assembly type 10 x 10 with an enrichment average of 3.69 wt % in U-235 and the assembly simulation assumes four cycles of operation of 18 months each one and presents an exposition of 47 G Wd/Tm to the discharge. The module OrigenArp of the Scale 6 code is the computation tool used for the assembly simulation and to obtain the results on the actinides record presents to the fuel discharge. The study covers the following points: a) Obtaining of the plutonium vector used in the fuel production of mixed oxides, and b) Power calculation and activity for present actinides to the discharge. The results presented in this work, correspond at the same time immediate of discharge (0 years) and to a cooling stage in the irradiated fuel pool (5 years). (Author)
Model calculating annual mean atmospheric dispersion factor for coastal site of nuclear power plant
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
This paper describes an atmospheric dispersion field experiment performed on the coastal site of nuclear power plant in the east part of China during 1995 to 1996. The three-dimension joint frequency are obtained by hourly observation of wind and temperature on a 100m high tower; the frequency of the “event day of land and sea breezes” are given by observation of surface wind and land and sea breezes; the diffusion parameters are got from measurements of turbulent and wind tunnel simulation test.A new model calculating the annual mean atmospheric dispersion factor for coastal site of nuclear power plant is developed and established.This model considers not only the effect from mixing release and mixed layer but also the effect from the internal boundary layer and variation of diffusion parameters due to the distance from coast.The comparison between results obtained by the new model and current model shows that the ratio of annual mean atmospheric dispersion factor gained by the new model and the current one is about 2.0.
Vaeth, Michael; Skovlund, Eva
2004-06-15
For a given regression problem it is possible to identify a suitably defined equivalent two-sample problem such that the power or sample size obtained for the two-sample problem also applies to the regression problem. For a standard linear regression model the equivalent two-sample problem is easily identified, but for generalized linear models and for Cox regression models the situation is more complicated. An approximately equivalent two-sample problem may, however, also be identified here. In particular, we show that for logistic regression and Cox regression models the equivalent two-sample problem is obtained by selecting two equally sized samples for which the parameters differ by a value equal to the slope times twice the standard deviation of the independent variable and further requiring that the overall expected number of events is unchanged. In a simulation study we examine the validity of this approach to power calculations in logistic regression and Cox regression models. Several different covariate distributions are considered for selected values of the overall response probability and a range of alternatives. For the Cox regression model we consider both constant and non-constant hazard rates. The results show that in general the approach is remarkably accurate even in relatively small samples. Some discrepancies are, however, found in small samples with few events and a highly skewed covariate distribution. Comparison with results based on alternative methods for logistic regression models with a single continuous covariate indicates that the proposed method is at least as good as its competitors. The method is easy to implement and therefore provides a simple way to extend the range of problems that can be covered by the usual formulas for power and sample size determination. Copyright 2004 John Wiley & Sons, Ltd.
Energy Technology Data Exchange (ETDEWEB)
Valdetaro, Eduardo Damianik, E-mail: valdtar@eletronuclear.gov.br [ELETRONUCLEAR - ELETROBRAS, Angra dos Reis, RJ (Brazil). Angra 2 Operating Dept.; Coordenacao dos Programas de Pos-Graduacao de Engenharia (PEN/COPPE/UFRJ), RJ (Brazil). Programa de Engenharia Nuclear; Schirru, Roberto, E-mail: schirru@lmp.ufrj.br [Coordenacao dos Programas de Pos-Graduacao de Engenharia (PEN/COPPE/UFRJ), RJ (Brazil). Programa de Engenharia Nuclear
2011-07-01
In Nuclear power plants, Data Reconciliation (DR) and Gross Errors Detection (GED) are techniques of increasing interest and are primarily used to keep mass and energy balance into account, which brings outcomes as a direct and indirect financial benefits. Data reconciliation is formulated by a constrained minimization problem, where the constraints correspond to energy and mass balance model. Statistical methods are used combined with the minimization of quadratic error form. Solving nonlinear optimization problem using conventional methods can be troublesome, because a multimodal function with differentiated solutions introduces some difficulties to search an optimal solution. Many techniques were developed to solve Data Reconciliation and Outlier Detection, some of them use, for example, Quadratic Programming, Lagrange Multipliers, Mixed-Integer Non Linear Programming and others use evolutionary algorithms like Genetic Algorithms (GA) and recently the use of the Particle Swarm Optimization (PSO) showed to be a potential tool as a global optimization algorithm when applied to data reconciliation. Robust Statistics is also increasing in interest and it is being used when measured data are contaminated by random errors and one can not assume the error is normally distributed, situation which reflects real problems situation. The aim of this work is to present a brief comparison between the classical data reconciliation technique and the robust data reconciliation and gross error detection with swarm intelligence procedure in calculating the thermal reactor power for a simplified heat circuit diagram of a steam turbine plant using real data obtained from Angra 2 Nuclear power plant. The main objective is to test the potential of the robust DR and GED method in a integrated framework using swarm intelligence and the three part redescending estimator of Hampel when applied to a real process condition. The results evaluate the potential use of the robust technique in
International Nuclear Information System (INIS)
Valdetaro, Eduardo Damianik; Coordenacao dos Programas de Pos-Graduacao de Engenharia; Schirru, Roberto
2011-01-01
In Nuclear power plants, Data Reconciliation (DR) and Gross Errors Detection (GED) are techniques of increasing interest and are primarily used to keep mass and energy balance into account, which brings outcomes as a direct and indirect financial benefits. Data reconciliation is formulated by a constrained minimization problem, where the constraints correspond to energy and mass balance model. Statistical methods are used combined with the minimization of quadratic error form. Solving nonlinear optimization problem using conventional methods can be troublesome, because a multimodal function with differentiated solutions introduces some difficulties to search an optimal solution. Many techniques were developed to solve Data Reconciliation and Outlier Detection, some of them use, for example, Quadratic Programming, Lagrange Multipliers, Mixed-Integer Non Linear Programming and others use evolutionary algorithms like Genetic Algorithms (GA) and recently the use of the Particle Swarm Optimization (PSO) showed to be a potential tool as a global optimization algorithm when applied to data reconciliation. Robust Statistics is also increasing in interest and it is being used when measured data are contaminated by random errors and one can not assume the error is normally distributed, situation which reflects real problems situation. The aim of this work is to present a brief comparison between the classical data reconciliation technique and the robust data reconciliation and gross error detection with swarm intelligence procedure in calculating the thermal reactor power for a simplified heat circuit diagram of a steam turbine plant using real data obtained from Angra 2 Nuclear power plant. The main objective is to test the potential of the robust DR and GED method in a integrated framework using swarm intelligence and the three part redescending estimator of Hampel when applied to a real process condition. The results evaluate the potential use of the robust technique in
International Nuclear Information System (INIS)
Tachibana, Masayuki; Noguchi, Yoshitaka; Fukunaga, Jyunichi; Hirano, Naomi; Yoshidome, Satoshi; Hirose, Takaaki
2009-01-01
The monitor unit (MU) was calculated by pencil beam convolution (inhomogeneity correction algorithm: batho power law) [PBC (BPL)] which is the dose calculation algorithm based on measurement in the past in the stereotactic lung irradiation study. The recalculation was done by analytical anisotropic algorithm (AAA), which is the dose calculation algorithm based on theory data. The MU calculated by PBC (BPL) and AAA was compared for each field. In the result of the comparison of 1031 fields in 136 cases, the MU calculated by PBC (BPL) was about 2% smaller than that calculated by AAA. This depends on whether one does the calculation concerning the extension of the second electrons. In particular, the difference in the MU is influenced by the X-ray energy. With the same X-ray energy, when the irradiation field size is small, the lung pass length is long, the lung pass length percentage is large, and the CT value of the lung is low, and the difference of MU is increased. (author)
Maneval, Daniel; Bouchard, Hugo; Ozell, Benoît; Després, Philippe
2018-01-01
The equivalent restricted stopping power formalism is introduced for proton mean energy loss calculations under the continuous slowing down approximation. The objective is the acceleration of Monte Carlo dose calculations by allowing larger steps while preserving accuracy. The fractional energy loss per step length ɛ was obtained with a secant method and a Gauss-Kronrod quadrature estimation of the integral equation relating the mean energy loss to the step length. The midpoint rule of the Newton-Cotes formulae was then used to solve this equation, allowing the creation of a lookup table linking ɛ to the equivalent restricted stopping power L eq, used here as a key physical quantity. The mean energy loss for any step length was simply defined as the product of the step length with L eq. Proton inelastic collisions with electrons were added to GPUMCD, a GPU-based Monte Carlo dose calculation code. The proton continuous slowing-down was modelled with the L eq formalism. GPUMCD was compared to Geant4 in a validation study where ionization processes alone were activated and a voxelized geometry was used. The energy straggling was first switched off to validate the L eq formalism alone. Dose differences between Geant4 and GPUMCD were smaller than 0.31% for the L eq formalism. The mean error and the standard deviation were below 0.035% and 0.038% respectively. 99.4 to 100% of GPUMCD dose points were consistent with a 0.3% dose tolerance. GPUMCD 80% falloff positions (R80 ) matched Geant’s R80 within 1 μm. With the energy straggling, dose differences were below 2.7% in the Bragg peak falloff and smaller than 0.83% elsewhere. The R80 positions matched within 100 μm. The overall computation times to transport one million protons with GPUMCD were 31-173 ms. Under similar conditions, Geant4 computation times were 1.4-20 h. The L eq formalism led to an intrinsic efficiency gain factor ranging between 30-630, increasing with the prescribed accuracy of simulations. The
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International Nuclear Information System (INIS)
Dawahra, S.; Khattab, K.
2012-01-01
The Monte Carlo method, using the MCNP4C code, was used in this paper to calculate the power distribution in 3-D geometry in the fuel rods of the Syrian Miniature Neutron Source Reactor (MNSR). To normalize the MCNP4C result to the steady state nominal thermal power, the appropriate scaling factor was defined to calculate the power distribution precisely. The maximum power of the individual rod was found in the fuel ring number 2 and was found to be 105 W. The minimum power was found in the fuel ring number 9 and was 79.9 W. The total power in the total fuel rods was 30.9 k W. This result agrees very well with nominal power reported in the reactor safety analysis report which equals 30 k W. Finally, the peak power factors, which are defined as the ratios between the maximum to the average and the maximum to the minimum powers were calculated to be 1.18 and 1.31 respectively. (author)
DP-THOT - a calculational tool for bundle-specific decay power based on actual irradiation history
International Nuclear Information System (INIS)
Johnston, S.; Morrison, C.A.; Albasha, H.; Arguner, D.
2005-01-01
A tool has been created for calculating the decay power of an individual fuel bundle to take account of its actual irradiation history, as tracked by the fuel management code SORO. The DP-THOT tool was developed in two phases: first as a standalone executable code for decay power calculation, which could accept as input an entirely arbitrary irradiation history; then as a module integrated with SORO auxiliary codes, which directly accesses SORO history files to retrieve the operating power history of the bundle since it first entered the core. The methodology implemented in the standalone code is based on the ANSI/ANS-5.1-1994 formulation, which has been specifically adapted for calculating decay power in irradiated CANDU reactor fuel, by making use of fuel type specific parameters derived from WIMS lattice cell simulations for both 37 element and 28 element CANDU fuel bundle types. The approach also yields estimates of uncertainty in the calculated decay power quantities, based on the evaluated error in the decay heat correlations built-in for each fissile isotope, in combination with the estimated uncertainty in user-supplied inputs. The method was first implemented in the form of a spreadsheet, and following successful testing against decay powers estimated using the code ORIGEN-S, the algorithm was coded in FORTRAN to create an executable program. The resulting standalone code, DP-THOT, accepts an arbitrary irradiation history and provides the calculated decay power and estimated uncertainty over any user-specified range of cooling times, for either 37 element or 28 element fuel bundles. The overall objective was to produce an integrated tool which could be used to find the decay power associated with any identified fuel bundle or channel in the core, taking into account the actual operating history of the bundles involved. The benefit is that the tool would allow a more realistic calculation of bundle and channel decay powers for outage heat sink planning
International Nuclear Information System (INIS)
Tian Yong; Zhang Longqiang; Yang Zhen; Yu Bin
2014-01-01
In order to ensure a long-term reliable operation of the DCS cabinet's 220 V AC power cable, it was needed to confirm whether the conductor temperature rise of power cable meet the requirement of the cable specification. Based on the actual data in site and the theory of numerical heat transfer, conservative model was established, and the conductor temperature was calculated. The calculation results show that the cable arrangement on the cable tray will not lead to the conductor temperature rise of power cable over than the required temperature in technical specification. (authors)
International Nuclear Information System (INIS)
Brik, A.
2009-01-01
In the first decade of June 2008, during the power commissioning of the reactor at the Mochovce NPP unit 1, the experiment with reducing the thermal power of core almost to the balance-of-plant (BOP) needs was performed. After the reactor has operated for seven hours at low power (about 200 220 MW (thermal)), its power was increased (at a rate of about 0.25% of N nom /min) to the initial level, close to 107% (1471 MW). During the experiment, core parameters, which were subsequently used for comparing the measured data with the results of experiment simulation calculations, were recorded in the reactor in-core monitoring system database. Calculated and measured levels of critical concentrations of boric acid were compared, along with power density distributions by fuel elements and assemblies obtained both by the KRUIZ in-core monitoring system and on the basis of calculations simulating reactor operation in accordance with the given core power variation schedule. The final stage consisted of assessing the methodical component of power density micro- and macro-fields calculation error in the core of Mochovce-1 reactor operating with varying load. (author)
International Nuclear Information System (INIS)
Brik, A.
2009-01-01
In the first decade of June 2008, during the power commissioning of the reactor at Mochovce NPP unit 1, the experiment with reducing the thermal power of core almost to the balance-of-plant needs was performed. After the reactor has operated for seven hours at low power (about 200 220 MW (thermal)), its power was increased (at a rate of about 0.25% of N nom /min) to the initial level, close to 107% (1471 MW). During the experiment, core parameters, which were subsequently used for comparing the measured data with the results of experiment simulation calculations, were recorded in the reactor in-core monitoring system's database. Calculated and measured levels of critical concentrations of boric acid were compared, along with power density distributions by fuel elements and assemblies obtained both by the KRUIZ in-core monitoring system and on the basis of calculations simulating reactor operation in accordance with the given core power variation schedule. The final stage consisted of assessing the methodical component of power density micro- and macro-fields' calculation error in the core of Mochovce-1 reactor operating with varying load. (Authors)
International Nuclear Information System (INIS)
Artemov, V.G.; Ivanov, A.S.; Kuznetsov, A.N.; Shemaev, Yu.P.
2015-01-01
The method of calculating the pin-wise power distribution by a combined method has been tested using the example of calculating the maneuvering regime. The combined method makes it possible to clarify the behavior of the linear fuel element load in comparison with the results of the superposition method in fuel assemblies with the regulator of the control and protection system in the boundaries of the control groups. The use of prepared on the basis of the results of macro calculation of the pin-wise characteristics, including 135Xe and 135I concentrations, allows to perform an adequate fine-grid calculation of the pin-wise power distribution without expensive calculation of feedbacks on a fine grid, which limits the application of a direct method for solving practical problems [ru
Biryuk, V. V.; Tsapkova, A. B.; Larin, E. A.; Livshiz, M. Y.; Sheludko, L. P.
2018-01-01
A set of mathematical models for calculating the reliability indexes of structurally complex multifunctional combined installations in heat and power supply systems was developed. Reliability of energy supply is considered as required condition for the creation and operation of heat and power supply systems. The optimal value of the power supply system coefficient F is based on an economic assessment of the consumers’ loss caused by the under-supply of electric power and additional system expences for the creation and operation of an emergency capacity reserve. Rationing of RI of the industrial heat supply is based on the use of concept of technological margin of safety of technological processes. The definition of rationed RI values of heat supply of communal consumers is based on the air temperature level iside the heated premises. The complex allows solving a number of practical tasks for providing reliability of heat supply for consumers. A probabilistic model is developed for calculating the reliability indexes of combined multipurpose heat and power plants in heat-and-power supply systems. The complex of models and calculation programs can be used to solve a wide range of specific tasks of optimization of schemes and parameters of combined heat and power plants and systems, as well as determining the efficiency of various redundance methods to ensure specified reliability of power supply.
Aberration design of zoom lens systems using thick lens modules.
Zhang, Jinkai; Chen, Xiaobo; Xi, Juntong; Wu, Zhuoqi
2014-12-20
A systematic approach for the aberration design of a zoom lens system using a thick lens module is presented. Each component is treated as a thick lens module at the beginning of the design. A thick lens module refers to a thick lens component with a real lens structure, like lens materials, lens curvatures, lens thicknesses, and lens interval distances. All nine third-order aberrations of a thick lens component are considered during the design. The relationship of component aberrations in different zoom positions can be approximated from the aberration shift. After minimizing the aberrations of the zoom lens system, the nine third-order aberrations of every lens component can be determined. Then the thick lens structure of every lens component can be determined after optimization according to their first-order properties and third-order aberration targets. After a third optimization for minimum practical third-order aberrations of a zoom lens system, the aberration design using the thick lens module is complete, which provides a practical zoom lens system with thick lens structures. A double-sided telecentric zoom lens system is designed using the thick lens module in this paper, which shows that this method is practical for zoom lens design.
Computerized calculation scheme for toric intraocular lenses.
Langenbucher, Achim; Seitz, Berthold
2004-06-01
While a number of intraocular lens (IOL) power prediction formulae are well established for determination of spherical lenses, no common strategy has been published for the computation of toric IOLs. The purpose of this study is to describe a paraxial computing scheme for tracing an axial pencil of rays through the 'optical system eye' containing astigmatic refractive surfaces with their axes at random. The capabilities of this computing scheme are demonstrated with clinical examples. Based on a schematic model eye with spherocylindric surfaces, we use two alternative notations for description of vergences or prescriptions: (1) standard notation (refraction in both cardinal meridians and axis), and (2) component notation (spherical equivalent and cylindric component in 0 degrees and 45 degrees. Refractive surfaces are added to the vergence in component notation, whereas the transformation of the vergence through media is performed in the standard notation for both cardinal meridians. For calculation of the toric lens implant, a pencil of rays is traced through the spectacle and the cornea to the estimated lens position as well as backwards from the retina to the estimated lens position. For calculation of residual spectacle refraction, a pencil of rays is traced backwards from the retina through the toric lens implant and the cornea to the spectacle plane. In example 1 we calculate a 'thin toric lens' for compensation of a corneal astigmatism to achieve a spherical target refraction. In example 2 we compute a 'thick toric lens', which has to compensate for an oblique corneal astigmatism and rotate the spectacle cylinder to the against the rule position to enhance near vision. In example 3 we estimate the residual refraction at the corneal plane after implantation of a thick toric lens, when the cylinder of the lens implant is compensating the corneal cylinder in part and the axis of implantation is not fully aligned with the axis of the corneal astigmatism. This
International Nuclear Information System (INIS)
Pina, C.M. de
1981-01-01
One of the most important part in neutronics calculations is the study of core behavior with inserted control rods. The first stage of this calculations consists in generating equivalent microscopic cross sections for the basic cells containing fuel or absorbed material. The cross sections will be then adjusted. The choice of parameters that help in those adjustments, were obtained by the comparisons of data coming from the control rod supercell calculations with the Hammer and Citation computer codes. The effect of those adjustments in core integral parameters was evaluated; in this work only the core power two-dimensional distribution calculations with the D bank completely inserted, is studied. (E.G.) [pt
Computerization of off-site dose calculations at two nuclear power plants
International Nuclear Information System (INIS)
Lei, W.; Robertson, C.E.; Moore, G.T.; Rawls, B.E.; Sipp, J.R.
1988-01-01
The Brunswick Nuclear Project (BNP) consists of two boiling water reactors designed to generate a total net output of 1642 MWe. Unit 2 achieved commercial production in 1975, and Unit 1 began commercial operation in 1977. The Harris nuclear Project (HNP) is an 860 MWe pressurized water reactor that entered commercial operation in May of 1987. both plant sites are operated by Carolina Power and Light Company (CP and L). During January 1984, BNP replaced its older effluent technical specifications (part of the plant's original license) with the newer generation of Radiological Effluent Technical Specifications (RETS) mandated by the U.S. Nuclear Regulatory Commission. The RETS for HNP were integrated directly into this initial technical specifications. The initial version of the ODCM for BNP was drafted by a vendor and then extensively rewritten by the plant staff. The manual for HNP was drafted by CP and L corporate staff. At the outset, it was realized how impractical it would be to attempt to manually perform all of the dose calculations and keep the necessary records. The alternative-computerization-required extensive in-plant and corporate efforts to identify the computing resources (hardware) needed, create the software for ODCM implementation, and test, verify, validate, and document the software. This paper discusses these efforts
Proskuryakov, K. N.
2017-11-01
Created new scientific direction: “Diagnosis, prognosis and prevention of vibration - acoustic resonances in the nuclear power plant (NPP) equipment. The possibility of using methods for calculating and analyzing electric oscillation systems in the study of the properties of acoustic systems with a two-phase medium is proved, based on the similarity of the differential equations describing the state of these systems. Is shown that the developed methods can be used to predict and prevent the occurrence of vibration - acoustic resonances in the NPP equipment. Is shown that the volume of pressurizer at NPPs with VVER and PWR as well as boiling water reactor that exploded at Japan’s NPP Fukushima Daiichi is a Helmholtz resonator, which contain water and steam volumes and able many times increases the impact on them of outside periodic oscillations. Paper presents most important results published long before the severe accidents at NPPs Three Mile Island (TMI), Chernobyl and Fukushima Daiichi that could be used for the prediction of a severe accident scenario, identification of measuring data and process control in order to minimize the damage. Worked out results also could be useful in another industrial technologies based on applications of single and two-phase flows.
Nuclear power and global warming: a first cost-benefit calculation
International Nuclear Information System (INIS)
Hope, C.
1994-01-01
This paper investigates the costs and benefits of a modest nuclear power programme in the European Union to combat the threat of global warming. The nuclear programme is found to bring a double benefit. The first and more obvious benefit is that the economic impacts of global warming are reduced. The second benefit is counter-intuitive; most people would expect it to be a cost. It comes from the stimulus to the economy from the construction of the nuclear plant, which, with the recycling of carbon tax revenues, offsets its construction and operating costs, and may even cause consumers' expenditure to rise. Calculations in this paper show that over the period to 2100 the mean net present value of the first benefit is 6 billion European Currency Units (ECU; 1 ECU is about Dollars 1), while the second benefit has a mean net present value of 159 billion ECU. However both benefits, particularly the second, are still very uncertain, to the extent that even their sign is not yet definitely established. (author)
Using radar wind profilers and RASS data to calculate power plant plume rise and transport
International Nuclear Information System (INIS)
Ping, Y.J.; Gaynor, J.E.
1994-01-01
As the number of 915-MHz radar wind profilers and radio acoustic sounding systems (RASS) increases, their number of uses also increases. These systems have demonstrated particular utility in air quality studies and, more specifically, in complex terrain. One data set from the radar profilers that has not, to date, been utilized to any large extent is represented by the temperature profiles derived from the RASS. Normally, these profiles represent a 5-min average every hour with a height resolution of about 60 m, a minimum range of about 100 m, and a maximum range of about 1.5 km, although this varies substantially with meterological conditions. Such profiles have several potential applications. Among them are determinations of mixing height and stability. In this work, we use the stability, along with the hour-averaged wind profiles, to estimate plume rise heights at a power plant site in Laughlin, Nevada, about 200 km south of Lake Mead. The profiles are first stratified according to season and synoptic categories so that the calculated plume rise heights could be separated by background transport conditions. The data were taken during Project Measurement of Haze and Visual Effects (MOHAVE), which took place in 1992. This project is briefly discussed in the next section, along with the instrumentation and data used in this study
Using radar wind profilers and RASS data to calculate power plant plume rise and transport
Energy Technology Data Exchange (ETDEWEB)
Ping, Y.J. [Univ. of Colorado, Boulder, CO (United States); Gaynor, J.E. [NOAA/ERL Wave Propagation Lab., Boulder, CO (United States)
1994-12-31
As the number of 915-MHz radar wind profilers and radio acoustic sounding systems (RASS) increases, their number of uses also increases. These systems have demonstrated particular utility in air quality studies and, more specifically, in complex terrain. One data set from the radar profilers that has not, to date, been utilized to any large extent is represented by the temperature profiles derived from the RASS. Normally, these profiles represent a 5-min average every hour with a height resolution of about 60 m, a minimum range of about 100 m, and a maximum range of about 1.5 km, although this varies substantially with meterological conditions. Such profiles have several potential applications. Among them are determinations of mixing height and stability. In this work, we use the stability, along with the hour-averaged wind profiles, to estimate plume rise heights at a power plant site in Laughlin, Nevada, about 200 km south of Lake Mead. The profiles are first stratified according to season and synoptic categories so that the calculated plume rise heights could be separated by background transport conditions. The data were taken during Project Measurement of Haze and Visual Effects (MOHAVE), which took place in 1992. This project is briefly discussed in the next section, along with the instrumentation and data used in this study.
Analysis of the reduced wake effect for available wind power calculation during curtailment
Sanchez Perez Moreno, S.; Ummels, B. C.; Zaayer, M B
2017-01-01
With the increase of installed wind power capacity, the contribution of wind power curtailment to power balancing becomes more relevant. Determining the available power during curtailment at the wind farm level is not trivial, as curtailment changes the wake effects in a wind farm. Current best
Yost, Dillon C.; Yao, Yi; Kanai, Yosuke
2017-09-01
In ion irradiation processes, electronic stopping power describes the energy transfer rate from the irradiating ion to the target material's electrons. Due to the scarcity and significant uncertainties in experimental electronic stopping power data for materials beyond simple solids, there has been growing interest in the use of first-principles theory for calculating electronic stopping power. In recent years, advances in high-performance computing have opened the door to fully first-principles nonequilibrium simulations based on real-time time-dependent density functional theory (RT-TDDFT). While it has been demonstrated that the RT-TDDFT approach is capable of predicting electronic stopping power for a wide range of condensed matter systems, there has yet to be an exhaustive examination of the physical and numerical approximations involved and their effects on the calculated stopping power. We discuss the results of such a study for crystalline silicon with protons as irradiating ions. We examine the influences of key approximations in RT-TDDFT nonequilibrium simulations on the calculated electronic stopping power, including approximations related to basis sets, finite size effects, exchange-correlation approximation, pseudopotentials, and more. Finally, we propose a simple and efficient correction scheme to account for the contribution from core-electron excitations to the stopping power, as it was found to be significant for large proton velocities.
International Nuclear Information System (INIS)
Berger, M.J.
1993-01-01
A PC package is documented for calculating stopping powers and ranges of electrons, protons and helium ions in matter for energies from 1 keV up to 10 GeV. Stopping powers and ranges for electrons can be calculated for any element, compound or mixture. Stopping powers and ranges of protons and helium ions can be calculated for 74 materials (26 elements and 48 compounds and mixtures). The files are stored on two HD diskettes in compressed form. Both executable files for IBM PC and Fortran-77 source files are provided. All three programs require 5.2 Mb of disk space. This set of two diskettes with detailed documentation is available upon request, cost free, from the IAEA Nuclear Data Section. (author). 25 refs, 4 tabs
International Nuclear Information System (INIS)
Haffner, D.R.
1976-01-01
1 - Description of problem or function: PACTOLUS is a code for computing nuclear power costs using the discounted cash flow method. The cash flows are generated from input unit costs, time schedules and burnup data. CLOTHO calculates and communicates to PACTOLUS mass flow data to match a specified load factor history. 2 - Method of solution: Plant lifetime power costs are calculated using the discounted cash flow method. 3 - Restrictions on the complexity of the problem - Maxima of: 40 annual time periods into which all costs and mass flows are accumulated, 20 isotopic mass flows charged into and discharged from the reactor model
International Nuclear Information System (INIS)
Medrano Asensio, Gregorio.
1976-06-01
A detailed power distribution calculation in a large power reactor requires the solution of the multigroup 3D diffusion equations. Using the finite difference method, this computation is too expensive to be performed for design purposes. This work is devoted to the single channel continous synthesis method: the choice of the trial functions and the determination of the mixing functions are discussed in details; 2D and 3D results are presented. The method is applied to the calculation of the IAEA ''Benchmark'' reactor and the results obtained are compared with a finite element resolution and with published results [fr
International Nuclear Information System (INIS)
Petitcolas, H.; Besson, A.; Bevilacqua, A.; Cosoli, G.
1984-09-01
Eight samples, which represent different materials used in testing reactors, were irradiated in the device ''CYRANO'' placed in the water reflector at different distances from the reactor core. The power dissipated in the device was measured by the ''CYRANO'' equipment itself, whereas the calorimeter juxtaposed served to monitor the gamma flux. Parallel to each experiment, the power deposited in the samples, the device materials and the calorimeter was calculated by the code MERCURE 4. The measured values were compared with the calculated ones, both in relative and in absolute values, for each sample and for each distance in the reflector. The comparison shows very good agreement [fr
Bioinspired adaptive gradient refractive index distribution lens
Yin, Kezhen; Lai, Chuan-Yar; Wang, Jia; Ji, Shanzuo; Aldridge, James; Feng, Jingxing; Olah, Andrew; Baer, Eric; Ponting, Michael
2018-02-01
Inspired by the soft, deformable human eye lens, a synthetic polymer gradient refractive index distribution (GRIN) lens with an adaptive geometry and focal power has been demonstrated via multilayer coextrusion and thermoforming of nanolayered elastomeric polymer films. A set of 30 polymer nanolayered films comprised of two thermoplastic polyurethanes having a refractive index difference of 0.05 were coextruded via forced-assembly technique. The set of 30 nanolayered polymer films exhibited transmission near 90% with each film varying in refractive index by 0.0017. An adaptive GRIN lens was fabricated from a laminated stack of the variable refractive index films with a 0.05 spherical GRIN. This lens was subsequently deformed by mechanical ring compression of the lens. Variation in the optical properties of the deformable GRIN lens was determined, including 20% variation in focal length and reduced spherical aberration. These properties were measured and compared to simulated results by placido-cone topography and ANSYS methods. The demonstration of a solid-state, dynamic focal length, GRIN lens with improved aberration correction was discussed relative to the potential future use in implantable devices.
Optical integration of Pancharatnam-Berry phase lens and dynamical phase lens
International Nuclear Information System (INIS)
Ke, Yougang; Liu, Yachao; Zhou, Junxiao; Liu, Yuanyuan; Luo, Hailu; Wen, Shuangchun
2016-01-01
In the optical system, most elements such as lens, prism, and optical fiber are made of silica glass. Therefore, integrating Pancharatnam-Berry phase elements into silica glass has potential applications in the optical system. In this paper, we take a lens, for example, which integrates a Pancharatnam-Berry phase lens into a conventional plano-convex lens. The spin states and positions of focal points can be modulated by controlling the polarization states of the incident beam. The proposed lens has a high transmission efficiency, and thereby acts as a simple and powerful tool to manipulate spin photons. Furthermore, the method can be conveniently extended to the optical fiber and laser cavity, and may provide a route to the design of the spin-photonic devices.
Calculation of core axial power shapes using alternating conditional expectation algorithm
International Nuclear Information System (INIS)
Lee, Eun Ki; Kim, Yong Hee; Cha, Kune Ho; Park, Moon Kyu
1998-01-01
We have introduced the alternating conditional expectation (ACE) algorithm in the method of reconstructing 20 node axial power shapes from five level detector powers. The ACE algorithm was used to find the optimal relationships between each plane power and normalized five detector powers. The obtained all optimal transformations had simple forms to be represented with polynomials. The reference axial power shapes and simulated detector powers were drawn out of the 3-dimensional results of Reactor Operation and Control Simulation (ROCS) code for various core states. By the ACE algorithm, we obtained the optimal relationship between dependent variable plane power, y, and independent variable detector powers, {Di, i=1,...,5 without any preprocessing, where a total of ≅3490 data sets per each cycle of YongGwang Nuclear (YGN) Power Plant units 3 and 4 are used. To test the validity and accuracy of the new method, about 21,200 cases of reconstructed axial power shapes are compared to original ROCS axial power shapes, and they are also contrasted with those obtained by Fourier fitting method (FFM). The average error of root mean square (rms), axial peak (DFZ), and axial shape index (DASI) of our new method for total 21204 data cases are 0.81%, 0.51% and 0.00204, while FFM 2.29%, 2.37% and 0.00264, respectively. The evaluation results for the data sets not used in the ACE transformations also show that the accuracy of new method is much better than that of FFM
ORIGEN2.1 Cycle Specific Calculation of Krsko Nuclear Power Plant Decay Heat and Core Inventory
International Nuclear Information System (INIS)
Vukovic, J.; Grgic, D.; Konjarek, D.
2010-01-01
This paper presents ORIGEN2.1 computer code calculation of Krsko Nuclear Power Plant core for Cycle 24. The isotopic inventory, core activity and decay heat are calculated in one run for the entire core using explicit depletion and decay of each fuel assembly. Separate pre-ori application which was developed is utilized to prepare corresponding ORIGEN2.1 inputs. This application uses information on core loading pattern to determine fuel assembly specific depletion history using 3D burnup which is obtained from related PARCS computer code calculation. That way both detailed single assembly calculations as well as whole core inventory calculations are possible. Because of the immense output of the ORIGEN2.1, another application called post-ori is used to retrieve and plot any calculated property on the basis of nuclide, element, summary isotope or group of elements for activation products, actinides and fission products segments. As one additional possibility, with the post-ori application it is able to calculate radiotoxicity from calculated ORIGEN2.1 inventory. The results which are obtained using the calculation model of ORIGEN2.1 computer code are successfully compared against corresponding ORIGEN-S computer code results.(author).
Directory of Open Access Journals (Sweden)
Elsa Tavernier
Full Text Available We aimed to examine the extent to which inaccurate assumptions for nuisance parameters used to calculate sample size can affect the power of a randomized controlled trial (RCT. In a simulation study, we separately considered an RCT with continuous, dichotomous or time-to-event outcomes, with associated nuisance parameters of standard deviation, success rate in the control group and survival rate in the control group at some time point, respectively. For each type of outcome, we calculated a required sample size N for a hypothesized treatment effect, an assumed nuisance parameter and a nominal power of 80%. We then assumed a nuisance parameter associated with a relative error at the design stage. For each type of outcome, we randomly drew 10,000 relative errors of the associated nuisance parameter (from empirical distributions derived from a previously published review. Then, retro-fitting the sample size formula, we derived, for the pre-calculated sample size N, the real power of the RCT, taking into account the relative error for the nuisance parameter. In total, 23%, 0% and 18% of RCTs with continuous, binary and time-to-event outcomes, respectively, were underpowered (i.e., the real power was 90%. Even with proper calculation of sample size, a substantial number of trials are underpowered or overpowered because of imprecise knowledge of nuisance parameters. Such findings raise questions about how sample size for RCTs should be determined.
Lucas, Greg M.; Love, Jeffrey J.; Kelbert, Anna
2018-02-01
Commonly, one-dimensional (1-D) Earth impedances have been used to calculate the voltages induced across electric power transmission lines during geomagnetic storms under the assumption that much of the three-dimensional structure of the Earth gets smoothed when integrating along power transmission lines. We calculate the voltage across power transmission lines in the mid-Atlantic region with both regional 1-D impedances and 64 empirical 3-D impedances obtained from a magnetotelluric survey. The use of 3-D impedances produces substantially more spatial variance in the calculated voltages, with the voltages being more than an order of magnitude different, both higher and lower, than the voltages calculated utilizing regional 1-D impedances. During the March 1989 geomagnetic storm 62 transmission lines exceed 100 V when utilizing empirical 3-D impedances, whereas 16 transmission lines exceed 100 V when utilizing regional 1-D impedances. This demonstrates the importance of using realistic impedances to understand and quantify the impact that a geomagnetic storm has on power grids.
Lucas, Greg M.; Love, Jeffrey J.; Kelbert, Anna
2018-01-01
Commonly, one-dimensional (1-D) Earth impedances have been used to calculate the voltages induced across electric power transmission lines during geomagnetic storms under the assumption that much of the three-dimensional structure of the Earth gets smoothed when integrating along power transmission lines. We calculate the voltage across power transmission lines in the mid-Atlantic region with both regional 1-D impedances and 64 empirical 3-D impedances obtained from a magnetotelluric survey. The use of 3-D impedances produces substantially more spatial variance in the calculated voltages, with the voltages being more than an order of magnitude different, both higher and lower, than the voltages calculated utilizing regional 1-D impedances. During the March 1989 geomagnetic storm 62 transmission lines exceed 100 V when utilizing empirical 3-D impedances, whereas 16 transmission lines exceed 100 V when utilizing regional 1-D impedances. This demonstrates the importance of using realistic impedances to understand and quantify the impact that a geomagnetic storm has on power grids.
Kressig, A.
2017-12-01
BACKGROUND The Greenhouse Gas Protocol (GHGP), Scope 2 Guidance standardizes how companies measure greenhouse gas emissions from purchased or independently generated electricity (called "scope 2 emissions"). Additionally, the interlinkages between industrial or commercial (nonresidential) energy requirements and water demands have been studied extensively, mostly at the national or provincial scale, focused on industries involved in power generation. However there is little guidance available for companies to systematically and effectively quantify water withdrawals and consumption (herein referred to as "water demand") associated with purchased or acquired electricity(what we call "Scope 2 Water"). This lack of guidance on measuring a company's water demand from electricity use is due to a lack of data on average consumption and withdrawal rates of water associated with purchased electricity. OBJECTIVE There is growing demand from companies in the food, beverage, manufacturing, information communication and technology, and other sectors for a methodology to quantify Scope 2 water demands. By understanding Scope 2 water demands, companies could evaluate their exposure to water-related risks associated with purchased or acquired electricity, and quantify the water benefits of changing to less water-intensive sources of electricity and energy generation such as wind and solar. However, there has never been a way of quantifying Scope 2 Water consumption and withdrawals for a company across its international supply chain. Even with interest in understanding exposure to water related risk and measuring water use reductions, there has been no quantitative way of measuring this information. But WRI's Power Watch provides the necessary data to allow for the Scope 2 Water accounting, because it will provide water withdrawal and consumption rates associated with purchased electricity at the power plant level. By calculating the average consumption and withdrawal rates per
Calculation of nuclide inventory, decay power, activity and dose rates for spent nuclear fuel
International Nuclear Information System (INIS)
Haakansson, Rune
2000-03-01
The nuclide inventory was calculated for a BWR and a PWR fuel element, with burnups of 38 and 55 MWd/kg uranium for the BWR fuel, and 42 and 60 MWd/kg uranium for the PWR fuel. The calculations were performed for decay times of up to 300,000 years. Gamma and neutron dose rates have been calculated at a distance of 1 m from a bare fuel element and outside the spent fuel canister. The calculations were performed using the CASMO-4 code
Design of a nonimaging Fresnel lens for solar concentrators
Energy Technology Data Exchange (ETDEWEB)
Leutz, R.; Akisawa, Atushi; Kashiwagi, Takao [Tokyo University of Agriculture and Technology (Japan). Dept. of Mechanical Systems Engineering; Suzuki, Akio [UNESCO, Paris (France)
1999-04-01
An optimum convex shaped nonimaging Fresnel lens is designed following the edge ray principle. The lens is evaluated by tracing rays and calculating a projective optical concentration ratio. This Fresnel lens is intended for use in evacuated tube type solar concentrators, generating mid-temperature heat to drive sorption cycles, or provide industrial process heat. It can also be used along with a secondary concentrator in photovoltaic applications. (author)
Optical design of transmitter lens for asymmetric distributed free space optical networks
Wojtanowski, Jacek; Traczyk, Maciej
2018-05-01
We present a method of transmitter lens design dedicated for light distribution shaping on a curved and asymmetric target. In this context, target is understood as a surface determined by hypothetical optical detectors locations. In the proposed method, ribbon-like surfaces of arbitrary shape are considered. The designed lens has the task to transform collimated and generally non-uniform input beam into desired irradiance distribution on such irregular targets. Desired irradiance is associated with space-dependant efficiency of power flow between the source and receivers distributed on the target surface. This unconventional nonimaging task is different from most illumination or beam shaping objectives, where constant or prescribed irradiance has to be produced on a flat target screen. The discussed optical challenge comes from the applications where single transmitter cooperates with multitude of receivers located in various positions in space and oriented in various directions. The proposed approach is not limited to optical networks, but can be applied in a variety of other applications where nonconventional irradiance distribution has to be engineered. The described method of lens design is based on geometrical optics, radiometry and ray mapping philosophy. Rays are processed as a vector field, each of them carrying a certain amount of power. Having the target surface shape and orientation of receivers distribution, the rays-surface crossings map is calculated. It corresponds to the output rays vector field, which is referred to the calculated input rays spatial distribution on the designed optical surface. The application of Snell's law in a vector form allows one to obtain surface local normal vector and calculate lens profile. In the paper, we also present the case study dealing with exemplary optical network. The designed freeform lens is implemented in commercially available optical design software and irradiance three-dimensional spatial distribution is
Energy Technology Data Exchange (ETDEWEB)
Kim, Jangyeol; Son, Kwangseop; Lee, Youngjun; Cheon, Sewoo; Cha, Kyoungho; Lee, Jangsoo; Kwon, Keechoon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2013-05-15
We confirmed that the coverage criteria for a safety-grade optical modem of a Core Protection Calculator is satisfactory using a traceability analysis matrix between high-level requirements and lower-level system test case data set. This paper describes the test environment, test components and items, a traceability analysis, and system tests as a result of system verification and validation based on Software Requirement Specifications (SRS) for a safety-grade optical modem of a Core Protection Calculator (CPC) in a Korea Standard Nuclear Power Plant (KSNP), and Software Design Specifications (SDS) for a safety-grade optical modem of a CPC in a KSNP. All tests were performed according to the test plan and test procedures. Functional testing, performance testing, event testing, and scenario based testing for a safety-grade optical modem of a Core Protection Calculator in a Korea Standard Nuclear Power Plant as a thirty-party verifier were successfully performed.
Directory of Open Access Journals (Sweden)
Mirko Grljušić
2015-05-01
Full Text Available The aim of this research was to investigate the possibility of a combined heat & power (CHP plant, using the waste heat from a Suezmax-size oil tanker’s main engine, to meet all heating and electricity requirements during navigation. After considering various configurations, a standard propulsion engine operating at maximum efficiency, combined with a supercritical Organic Rankine cycle (ORC system, was selected to supply the auxiliary power, using R245fa or R123 as the working fluid. The system analysis showed that such a plant can meet all heat and electrical power requirements at full load, with the need to burn only a small amount of supplementary fuel in a heat recovery steam generator (HRSG when the main engine operates at part load. Therefore, it is possible to increase the overall thermal efficiency of the ship’s power plant by more than 5% when the main engine operates at 65% or more of its specified maximum continuous rating (SMCR.
DEFF Research Database (Denmark)
Gao, Ming-zhi; Chen, Min; Jin, Cheng
2013-01-01
Parallel operation of distributed generation is an important topic for microgrids, which can provide a highly reliable electric supply service and good power quality to end customers when the utility is unavailable. However, there is a well-known limitation: the power sharing accuracy between...
Fast calculation of electrical transients in power systems after a change of topology
Thomas, R.
2017-01-01
A power system is composed of various components such as generators, transformers, transmission lines, switching devices and loads. They have their mathematical model and graphical representation. Sometimes, a power system’s change of topology occurs due to events like short circuits, lightning
International Nuclear Information System (INIS)
Edy-Sulistyono
1996-01-01
Burn up dependence of fission gas released and variation power analysis have been conducted using FEMXI-IV computer code program for Pressure Water Reactor Fuel During steady-state condition. The analysis result shows that the fission gas release is sensitive to the fuel temperature, the increasing of burn up and power in the fuel element under irradiation experiment
International Nuclear Information System (INIS)
Latkowski, J.F.; Sanz, J.; Vujic, J.L.
1996-01-01
Inertial fusion energy (IFE) and magnetic fusion energy (MFE) power plants will probably operate in a pulsed mode. The two different schemes, however, will have quite different time periods. Typical repetition rates for IFE power plants will be 1-5 Hz. MFE power plants will ramp up in current for about 1 hour, shut down for several minutes, and repeat the process. Traditionally, activation calculations for IFE and MFE power plants have assumed continuous operation and used either the ''steady state'' (SS) or ''equivalent steady state'' (ESS) approximations. It has been suggested recently that the SS and ESS methods may not yield accurate results for all radionuclides of interest. The present work expands that of Sisolak, et al. by applying their formulae to conditions which might be experienced in typical IFE and MFE power plants. In addition, complicated, multi-step reaction/decay chains are analyzed using an upgraded version of the ACAB radionuclide generation/depletion code. Our results indicate that the SS method is suitable for application to MFE power plant conditions. We also find that the ESS method generates acceptable results for radionuclides with half-lives more than a factor of three greater than the time between pulses. For components that are subject to 0.05 Hz (or more frequent) irradiation (such as coolant), use of the ESS method is recommended. For components or materials that are subject to less frequent irradiation (such as high-Z target materials), pulsed irradiation calculations should be used
International Nuclear Information System (INIS)
Pogosbekyan, L.R.; Lysov, D.A.; Bronitskii, L.L.
1993-01-01
Numerical simulators and information systems that support nuclear reactor operators must have fast models to estimate how fuel reloads and control rod displacement affect neutron and power distributions in the core. The consequences of reloads and control rod displacement cannot be evaluated correctly without considering local automatic control-rod operations in maintaining the radial power distribution. Fast three-dimensional models to estimate the effects of reloads and displacement of the control and safety rods have already been examined. I.V. Zonov et al. used the following assumptions in their calculational model: (1) the full-scale problem could be reduced a three-dimensional fragment of a locally perturbed core, and (2) the boundary conditions of the fragment and its total power were constant. The last assumption considers approximately how local automatic control rods stabilize the radial power distribution, but three dimensional calculations with these rods are not considered. These assumptions were introduced to obtain high computational speed. I.L. Bronitskii et al. considered in more detail how moving the local automatic control rods affect the power dimensional in the three-dimensional fragment, because, with on-line monitoring of the reload process, information on control rod positions is periodically renewed, and the calculations are done in real time. This model to predict the three-dimensional power distribution to (1) do a preliminary reload analysis, and (2) prepare the core for reloading did not consider the effect of perturbations from the local automatic control rods. Here we examine a model of a stationary neutron distribution. On one hand it gives results in an acceptable computation time; on the other it is a full-scale three-dimensional model and considers how local automatic control rods affect both the radial and axial power distribution
Computer optimization of retarding lens systems for ESCA spectrometers
International Nuclear Information System (INIS)
Wannberg, B.; Skoellermo, A.
1977-01-01
The performance of four-element electrostatic lenses as retarding systems between source and analyzer in ESCA spectrometers is calculated. The potential distribution in the lens is defined by an axial potential of the type phi(z)=V 0 +Σ(Vsub(i)-Vsub(i-1))/2 - tanh (ω/asub(i)(z-zsub(i))). For a given general shape of the lens and a given retardation ratio, the potentials of the two middle electrodes are fitted to give a paraxial image with a prescribed magnification at the exit slit of the lens system. The equipotential surfaces forming the electrodes are found by calculating the potential in an off-axis point, using the series expansion. All third-order geometrical and first-order chromatic aberrations of the lenses are calculated and used together with the second-order aberrations of the analyzer to calculate optimum dimensions of the lens elements and of the emittance-defining slits. A computer program, of which one part calculates the lens properties and one the properties of the entire system lens-analyzer, is described. Two lens systems are presented in some detail. The first one is intended for use with a hemispherical electrostatic analyzer. The angular acceptance is here defined by an aperture stop inside the lens. In this system, the image position and magnification can be kept constant for retardation ratios at least between 1:2 and 60:1, with moderate potentials on the middle electrodes. The second lens system is designed for a magnetic spectrometer of the π√2-type. Here, the central trajectory in the lens is slightly curved by the magnetic field, and the angular acceptance is defined by a baffle after the lens. This system is optimized for a constant retardation ratio of 5:1. (Auth.)
The Impact of Harmonics Calculation Methods on Power Quality Assessment in Wind Farms
DEFF Research Database (Denmark)
Kocewiak, Lukasz Hubert; Hjerrild, Jesper; Bak, Claus Leth
2010-01-01
Different methods of calculating harmonics in measurements obtained from offshore wind farms are shown in this paper. Appropriate data processing methods are suggested for harmonics with different origin and nature. Enhancements of discrete Fourier transform application in order to reduce...... measurement data processing errors are proposed and compared with classical methods. Comparison of signal processing methods for harmonic studies is presented and application dependent on harmonics origin and nature recommended. Certain aspects related to magnitude and phase calculation in stationary...... measurement data are analysed and described. Qualitative indices of measurement data harmonic analysis in order to assess the calculation accuracy are suggested and used....
Directory of Open Access Journals (Sweden)
R.V. Zaitsev
2016-09-01
Full Text Available Purpose. To ensure maximum production of electric power by photovoltaic vacilities, in addition to using highly efficient photovoltaic modules equipped with solar radiation concentrators must use a highly effective power take-off system. This paper is inscribed to solving the problem of a highly efficient and economic power take-off system development. Methodology. To solving the problem, we implemented three stages. On the first stage examines the dependence of electrical power from the intensity of the incident solar radiation. Based on this, the second stage is calculated the DC-DC converter resonant circuit and its working parameters, and developed circuit diagram of DC-DC converter. On the third stage, we carry out an analysis of power take-off system with step up DC-DC converter working. Results. In this paper, we carry out the analysis of working efficiency for photovoltaic facility power take-off system with step-up boost converter. The result of such analysis show that the efficiency of such system in a wide range of photovoltaic energy module illumination power is at 0.92, whereas the efficiency of classic power take-off systems does not exceed 0.70. Achieved results allow designing a circuit scheme of a controlled bridge resonant step-up converter with digital control. Proposed scheme will ensure reliable operation, fast and accurate location point of maximum power and conversion efficiency up to 0.96. Originality. Novelty of proposed power take-off system solution constitute in implementation of circuit with DC-DC converters, which as it shown by results of carrying out modeling is the most effective. Practical value. Practical implementation of proposed power take-off system design will allow reducing losses in connective wires and increasing the efficiency of such a system up to 92.5% in wide range of photovoltaic energy modules illumination.
Directory of Open Access Journals (Sweden)
Mikulović Jovan Č.
2014-01-01
Full Text Available A methodology for calculation of overvoltages in transformer windings, based on a numerical method of inverse Laplace transform, is presented. Mathematical model of transformer windings is described by partial differential equations corresponding to distributed parameters electrical circuits. The procedure of calculating overvoltages is applied to windings having either isolated neutral point, or grounded neutral point, or neutral point grounded through impedance. A comparative analysis of the calculation results obtained by the proposed numerical method and by analytical method of calculation of overvoltages in transformer windings is presented. The results computed by the proposed method and measured voltage distributions, when a voltage surge is applied to a three-phase 30 kVA power transformer, are compared. [Projekat Ministartsva nauke Republike Srbije, br. TR-33037 i br. TR-33020
Directory of Open Access Journals (Sweden)
Niancheng Zhou
2018-03-01
Full Text Available Short-circuit current level of power grid will be increased with high penetration of VSC-based renewable energy, and a strong coupling between transient fault process and control strategy will change the fault features. The full current expression of VSC-based renewable energy was obtained according to transient characteristics of short-circuit current. Furtherly, by analyzing the closed-loop transfer function model of controller and current source characteristics presented in steady state during a fault, equivalent circuits of VSC-based renewable energy of fault transient state and steady state were proposed, respectively. Then the correctness of the theory was verified by experimental tests. In addition, for power grid with VSC-based renewable energy, superposition theorem was used to calculate AC component and DC component of short-circuit current, respectively, then the peak value of short-circuit current was evaluated effectively. The calculated results could be used for grid planning and design, short-circuit current management as well as adjustment of relay protection. Based on comparing calculation and simulation results of 6-node 500 kV Huainan power grid and 35-node 220 kV Huaisu power grid, the effectiveness of the proposed method was verified.
Calculation methods for analysing nuclear power plant accidents and its qualification
International Nuclear Information System (INIS)
Sacco, W.
1986-01-01
A methodology of transient and accident analyses able to carried out calculations for all transients and accidents required to support operation and operation licensing of Angra-1 reactor reload, is presented. (M.C.K.) [pt
3-D ASE calculation for high power output XeCl excimer lasers
International Nuclear Information System (INIS)
Tu Qinfen; Zhang Jianquan; Wu Baosheng
1996-01-01
The 3-dimensional ASE calculation for electron beam pumping XeCl excimer laser is presented by M-C method. In the model wall-reflected ASE is included. This calculation also includes non-saturable absorption and mirror that reflect ASE flux back into the active gain medium. Results show optimum scaling of injected flux. It can provide theoretical basis and experimental references for experiments on excimer lasers, and be extrapolated to any other type of laser
Properties of the cathode lens combined with a focusing magnetic/immersion-magnetic lens
Czech Academy of Sciences Publication Activity Database
Konvalina, Ivo; Müllerová, Ilona
2011-01-01
Roč. 645, č. 1 (2011), s. 55-59 ISSN 0168-9002 R&D Projects: GA ČR GAP102/10/1410; GA AV ČR IAA100650902; GA MŠk ED0017/01/01 Institutional research plan: CEZ:AV0Z20650511 Keywords : cathode lens * compound objective lens * aberration coefficients * spot size * field calculations Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.207, year: 2011
Development of Powerhouse Using Fresnel lens
Directory of Open Access Journals (Sweden)
Al-Dohani Nawar Saif
2018-01-01
Full Text Available Solar energy is an alternative source of renewable energy. Sultanate of Oman government showed initiation on utilization of solar energy for domestic and industrial applications. Fresnel lens is one of the methods to collect maximum energy by gathering heat of the sun in the concentrated form (using solar collectors. Earlier research work discloses that Fresnel lens gave better result in terms of power output and produces lower heat loss as compared to linear –parabolic solar collectors. In this work, development of a proto Fresnel lens power house was made to generate electricity. The focused heat from Fresnel lens was used to heat the molten salt in a heat exchanger to produce the steam. The generated steam was used to rotate the steam engine coupled to a generator. In the current work, a maximum power of 30 W was produced. In addition, comparative study was carried out regarding solar salts and heat exchanger materials to understand the Fresnel powerhouse performance. Overall the present study gave valuable information regarding usage of Fresnel lens for electricity generation in Oman.
International Nuclear Information System (INIS)
Aydogdu, K.
1998-01-01
Nine components determine the moderator-system heat load during full-power operation and during a reactor power transient in a CANDU reactor. The components that contribute to the total moderator-system heat load at any time consist of the heat generated in the calandria tubes, guide tubes and reactivity mechanisms, moderator and reflector; the heat transferred from calandria shell, the inner tubesheets and the fuel channels; and the heat gained from moderator pumps and heat lost from piping. The contributions from each of these components will vary with time during a reactor transient. The sources of heat that arise from the deposition of nuclear energy can be divided into two categories, viz., a) the neutronic component (which is directly proportional to neutronic power), which includes neutron energy absorption, prompt-fission gamma absorption and capture gamma absorption; and b) the fission-product decay-gamma component, which also varies with time after initiation of the transient. An equation was derived to calculate transient heat loads to the moderator. The equation includes two independent variables that are the neutronic power and fission-product decay-gamma power fractions during the transient and a constant term that represents the heat gained from moderator pumps and heat lost from piping. The calculated heat load in the moderator during steady-state full-power operation for a CANDU 6 reactor was compared with available measurements from the Point Lepreau, Wolsong 1 and Gentilly-2 nuclear generating stations. The calculated and measured values were in reasonably good agreement. (author)
International Nuclear Information System (INIS)
Scott Ingram, W.; Robertson, Daniel; Beddar, Sam
2015-01-01
Liquid scintillators are a promising detector for high-resolution three-dimensional proton therapy dosimetry. Because the scintillator comprises both the active volume of the detector and the phantom material, an ideal scintillator will exhibit water equivalence in its radiological properties. One of the most fundamental of these is the scintillator’s stopping power. The objective of this study was to compare calculations and measurements of scintillator-to-water stopping power ratios to evaluate the suitability of the liquid scintillators BC-531 and OptiPhase HiSafe 3 for proton dosimetry. We also measured the relative scintillation output of the two scintillators. Both calculations and measurements show that the linear stopping power of OptiPhase is significantly closer to water than that of BC-531. BC-531 has a somewhat higher scintillation output. OptiPhase can be mixed with water at high concentrations, which further improves its scintillator-to-water stopping power ratio. However, this causes the solution to become cloudy, which has a negative impact on the scintillation output and spatial resolution of the detector. OptiPhase is preferred over BC-531 for proton dosimetry because its density and scintillator-to-water stopping power ratio are more water equivalent
International Nuclear Information System (INIS)
Ferreira, C.R.
1984-01-01
It is presented the absorption-production nodal method for steady and dynamical calculations in one-dimension and one group energy. It was elaborated the NOD1D computer code (in FORTRAN-IV language). Calculations of neutron flux and power distributions, burnup, effective multiplication factors and critical boron concentration were made with the NOD1D code and compared with results obtained through the CITATION code, which uses the finite difference method. The nuclear constants were produced by the LEOPARD code. (M.C.K.) [pt
Effects of Coupling Lens on Optical Refrigeration of Semiconductors
International Nuclear Information System (INIS)
Kai, Ding; Yi-Ping, Zeng
2008-01-01
Optical refrigeration of semiconductors is encountering efficiency difficulties caused by nonradiative recombination and luminescence trapping. A commonly used approach for enhancing luminescence efficiency of a semiconductor device is coupling a lens with the device. We quantitatively study the effects of a coupling lens on optical refrigeration based on rate equations and photon recycling, and calculated cooling efficiencies of different coupling mechanisms and of different lens materials. A GaAs/GaInP heterostructure coupled with a homo-epitaxial GaInP hemispherical lens is recommended. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
International Nuclear Information System (INIS)
Shaw, P.M.
1983-04-01
The computer code SARTEMP2, an extended version of the original SARTEMP program, which calculates the power and temperatures in a transport flask during a hypothetical criticality accident is described. The accident arises, it is assumed, during the refilling of the flask with water, bringing the system to delayed critical. As the water level continues to rise, reactivity is added causing the power to rise, and thus temperatures in the fuel, clad and water to increase. The point kinetics equations are coupled to the one-dimensional heat conduction equation. The model used, the method of solution of the equations and the input data required are given. (author)
International Nuclear Information System (INIS)
Cardile, F.P.; Bangart, R.L.; Collins, J.T.
1978-06-01
The Intergovernmental Maritime Consultative Organization IMCO) is currently preparing guidelines concerning the safety of nuclear-powered merchant ships. An important aspect of these guidelines is the determination of the releases of radioactive material in effluents from these ships and the control exercised by the ships over these releases. To provide a method for the determination of these releases, the NRC staff has developed a computerized model, the NMS-GEFF Code, which is described in the following chapters. The NMS-GEFF Code calculates releases of radioactive material in gaseous effluents for nuclear-powered merchant ships using pressurized water reactors
Capsular 'pits' in the human lens.
Harris, M. L.; Brown, N. A.; Shun-Shin, G. A.; Smith, G. T.
1992-01-01
The lens capsule is an atypical basement membrane surrounding the lens epithelial cells and lens fibres which make up the remainder of the human lens. A seemingly unreported morphological change visible in the lens capsule with the biomicroscope is described.
Adaptive mechanical-wetting lens actuated by ferrofluids
Cheng, Hui-Chuan; Xu, Su; Liu, Yifan; Levi, Shoshana; Wu, Shin-Tson
2011-04-01
We report an adaptive mechanical-wetting lens actuated by ferrofluids. The ferrofluids works like a piston to pump liquids in and out from the lens chamber, which in turn reshapes the lens curvature and changes the focal length. Both positive and negative lenses are demonstrated experimentally. The ferrofluid-actuated mechanical-wetting lens exhibits some attractive features, such as high resolution, fast response time, low power consumption, simple structure and electronic control, weak gravity effect, and low cost. Its potential applications in medical imaging, surveillance, and commercial electronics are foreseeable.
Particle swarm optimization applied to automatic lens design
Qin, Hua
2011-06-01
This paper describes a novel application of Particle Swarm Optimization (PSO) technique to lens design. A mathematical model is constructed, and merit functions in an optical system are employed as fitness functions, which combined radiuses of curvature, thicknesses among lens surfaces and refractive indices regarding an optical system. By using this function, the aberration correction is carried out. A design example using PSO is given. Results show that PSO as optical design tools is practical and powerful, and this method is no longer dependent on the lens initial structure and can arbitrarily create search ranges of structural parameters of a lens system, which is an important step towards automatic design with artificial intelligence.
Applications of supercomputing and the utility industry: Calculation of power transfer capabilities
International Nuclear Information System (INIS)
Jensen, D.D.; Behling, S.R.; Betancourt, R.
1990-01-01
Numerical models and iterative simulation using supercomputers can furnish cost-effective answers to utility industry problems that are all but intractable using conventional computing equipment. An example of the use of supercomputers by the utility industry is the determination of power transfer capability limits for power transmission systems. This work has the goal of markedly reducing the run time of transient stability codes used to determine power distributions following major system disturbances. To date, run times of several hours on a conventional computer have been reduced to several minutes on state-of-the-art supercomputers, with further improvements anticipated to reduce run times to less than a minute. In spite of the potential advantages of supercomputers, few utilities have sufficient need for a dedicated in-house supercomputing capability. This problem is resolved using a supercomputer center serving a geographically distributed user base coupled via high speed communication networks
International Nuclear Information System (INIS)
Ribeiro, Franciane; Mazer, Amanda Cristina; Hormaza, Joel Mesa
2016-01-01
In order to calculate the stopping power of protons, there are many very successful models at high energies, which are extrapolated to low-energy regions. From the point of view of application of proton beam in cancer treatment is just this low energy region the most relevant due to the dose deposition profile in depth for protons. In this work, we present a calculation of the stopping power of protons in a water target using the dielectric formalism in MELF-GOS approach. The results when compared to other models show good agreement for energies above 100 keV and lower values below this energy. This result should impact the range of values of protons and the Bragg peak position. (author)
Problems in calculating reactor model (primary circuit) for nuclear power plant diagnostics
International Nuclear Information System (INIS)
Markov, P.
1986-01-01
Some results are presented of the calculation of eigen-vibrations of the system of WWER-440 nuclear reactor vessels in a vacuum and in a liquid. Computer code BOSOR 4 has been written for calculating forced vibrations of shells with axial symmetry and of a simplified system of reactor vessels. A description is given of this code, which is based on the so-called energy method of finite differences. Briefly discussed is the feasibility of applying the results of the latest computation techniques in the diagnostics of the major components of a nuclear reactor. (Z.M.)
Basis calculation of phase cross section library in a low power fast reactor neutronic simulation
International Nuclear Information System (INIS)
Jachic, J.
1993-09-01
In order to implement the utilization of the efficient multidimensional cubic SPLINE interpolation, we determine the phase library bases for net like relevant state components. A generic cubic surface and a weighted plane pertinent alternative interpolating methods used capable to generate cross sections values for fixed coordinates from cell code calculated data points is used. It is verified that the phase library bases increases or decrease smoothly and monotonically with the spectrum asymmetry and total flux buckling. This justifies its use in cross section updating avoiding cell calculations. (author)
Calculation of high power relativistic beams with consideration of collision effects
International Nuclear Information System (INIS)
Sveshnikov, V.M.
1986-01-01
This paper considers the numerical calculation of relativistic charged particle beams moving in axisymmetric systems in which the presence of a residual neutral gas is possible. It is essential to consider phenomena related to collisions between charged particles and neutrals. Algorithms are constructed for numerical modeling of ionization processes within the framework of the ERA program complex. Solutions of model and practical problems are presented as examples. Such problems were studied where ionization processes were considered by a more complex method requiring a greater volume of calculations but valid at lower pressures
An Investigation on Hot-Spot Temperature Calculation Methods of Power Transformers
Ahmet Y. Arabul; Ibrahim Senol; Fatma Keskin Arabul; Mustafa G. Aydeniz; Yasemin Oner; Gokhan Kalkan
2016-01-01
In the standards of IEC 60076-2 and IEC 60076-7, three different hot-spot temperature estimation methods are suggested. In this study, the algorithms which used in hot-spot temperature calculations are analyzed by comparing the algorithms with the results of an experimental set-up made by a Transformer Monitoring System (TMS) in use. In tested system, TMS uses only top oil temperature and load ratio for hot-spot temperature calculation. And also, it uses some constants from standards which ar...
International Nuclear Information System (INIS)
Quintana, E.E.; Tossi, M.H.; Telleria, D.M.
1990-01-01
Collective doses produced during the normal working of the Atucha I Nuclear Power Plant are calculated using annual atmospheric factors. This work studies the behaviour of the dilution factors in different periods of the year in order to fit the calculated dose model applying factors from seasonal, monthly or weekly periods. The Radiation Protection Group of the C.N.E.A. have carried out continuous environmental monitoring in the surroundings of the Atucha I Nuclear Power Plant. These studies include the measurement of air tritium concentration, radionuclide that is found principally as tritiated water vapour. This isotope, normally released by the nuclear power plant was used as a tracer to assess the atmospheric dilution factors. Factors were calculated by two methods: an experimental one, based on environmental measurements of the tritium concentration in the surroundings of the nuclear power plant and another one by applying a theoretical model based on information from the micrometeorological tower located in the mentioned place. To carry out the environmental monitoring, four monitoring stations in the surroundings of the power plant were chosen. Three of them are approximately one kilometer from the plant and the fourth is 7.5 km away, near the city of Lima. To condense and collect the atmospheric water vapour, an overcooling system was used. The measurement was performed by liquid scintillation counting, previous alkaline electrolytical enrichment of the samples. The theoretical model uses hourly values of direction and wind intensity, as well as the atmospheric dispersive properties. Values obtained during the period 1976 to 1988 allowed, applying statistical tests, to validate the theoretical model and to observe seasonal variation of the dilution factors throughout the same year and between different years. Finally, results and graphics are presented showing that the behaviour of the dilution factors in different periods of the year. It is recommended to
Thermal-hydraulic calculation and analysis for QNPP (Qinshan Nuclear Power Plant) containment
International Nuclear Information System (INIS)
Xie Hui; Zhou Jie; He Yingchao
1993-01-01
Three containment thermal-hydraulic codes CONTEMPT-LT/028, CONTEMPT-4/MOD3 and COMPARE are used to compute and analyse the Qinshan Nuclear Power Plant (QNPP) containment response under LOCA or MSLB conditions. An evaluation of the capability of containment of QNPP is given
Harris, W F
1989-03-01
The exact equation for sagitta of spherical surfaces is generalized to toric surfaces which include spherical and cylindrical surfaces as special cases. Lens thickness, therefore, can be calculated accurately anywhere on a lens even in cases of extreme spherical and cylindrical powers and large diameters. The sagittae of tire- and barrel-form toric surfaces differ off the principal meridians, as is shown by a numerical example. The same holds for pulley- and capstan-form toric surfaces. A general expression is given for thickness at an arbitrary point on a toric lens. Approximate expressions are derived and re-expressed in terms of matrices. The matrix provides an elegant means of generalizing equations for spherical surfaces and lenses to toric surfaces and lenses.
International Nuclear Information System (INIS)
Moeller, M.P.; Scherpelz, R.I.; Desrosiers, A.E.
1982-01-01
This work analyzes the sensitivity of calculated doses to critical assumptions for offsite consequences following a PWR-2 accident at a nuclear power reactor. The calculations include three radiation dose pathways: internal dose resulting from inhalation, external doses from exposure to the plume, and external doses from exposure to contaminated ground. The critical parameters are the time period of integration for internal dose commitment and the duration of residence on contaminated ground. The data indicate the calculated offsite whole body dose will vary by as much as 600% depending upon the parameters assumed. When offsite radiation doses determine the size of emergency planning zones, this uncertainty has significant effect upon the resources allocated to emergency preparedness
Energy Technology Data Exchange (ETDEWEB)
Salazar, Mike A. (Albuquerque, NM); Foreman, Larry R. (Los Alamos, NM)
1997-01-01
This invention describes a method for fabricating an intraocular lens made rom clear Teflon.TM., Mylar.TM., or other thermoplastic material having a thickness of about 0.025 millimeters. These plastic materials are thermoformable and biocompatable with the human eye. The two shaped lenses are bonded together with a variety of procedures which may include thermosetting and solvent based adhesives, laser and impulse welding, and ultrasonic bonding. The fill tube, which is used to inject a refractive filling material is formed with the lens so as not to damage the lens shape. A hypodermic tube may be included inside the fill tube.
Energy Technology Data Exchange (ETDEWEB)
Salazar, M.A.; Foreman, L.R.
1997-07-08
This invention describes a method for fabricating an intraocular lens made from clear Teflon{trademark}, Mylar{trademark}, or other thermoplastic material having a thickness of about 0.025 millimeters. These plastic materials are thermoformable and biocompatable with the human eye. The two shaped lenses are bonded together with a variety of procedures which may include thermosetting and solvent based adhesives, laser and impulse welding, and ultrasonic bonding. The fill tube, which is used to inject a refractive filling material is formed with the lens so as not to damage the lens shape. A hypodermic tube may be included inside the fill tube. 13 figs.
Directory of Open Access Journals (Sweden)
Lin Yang
2018-01-01
Full Text Available In this paper, the calculation of the conductor temperature is related to the temperature sensor position in high-voltage power cables and four thermal circuits—based on the temperatures of insulation shield, the center of waterproof compound, the aluminum sheath, and the jacket surface are established to calculate the conductor temperature. To examine the effectiveness of conductor temperature calculations, simulation models based on flow characteristics of the air gap between the waterproof compound and the aluminum are built up, and thermocouples are placed at the four radial positions in a 110 kV cross-linked polyethylene (XLPE insulated power cable to measure the temperatures of four positions. In measurements, six cases of current heating test under three laying environments, such as duct, water, and backfilled soil were carried out. Both errors of the conductor temperature calculation and the simulation based on the temperature of insulation shield were significantly smaller than others under all laying environments. It is the uncertainty of the thermal resistivity, together with the difference of the initial temperature of each radial position by the solar radiation, which led to the above results. The thermal capacitance of the air has little impact on errors. The thermal resistance of the air gap is the largest error source. Compromising the temperature-estimation accuracy and the insulation-damage risk, the waterproof compound is the recommended sensor position to improve the accuracy of conductor-temperature calculation. When the thermal resistances were calculated correctly, the aluminum sheath is also the recommended sensor position besides the waterproof compound.
Optimum design of nonimaging Fresnel lens; Hiketsuzo fureneru renzu no saiteki sekkei
Energy Technology Data Exchange (ETDEWEB)
Leutz, R.; Komai, K.; Akisawa, A.; Kashiwagi, T. [Tokyo University of Agriculture and Technology, Tokyo (Japan); Suzuki, A. [Unesco, Paris (France). Associations in Japan
1999-11-25
An optimum convex shaped nonimaging Fresnel lens is designed following the edge ray principle. The lens is evaluated by tracing rays and calculating a projective optical concentration ratio. This Fresnel lens can used as concentrator in photovoltaic and solar thermal applications. (author)
Ensor, Joie; Burke, Danielle L; Snell, Kym I E; Hemming, Karla; Riley, Richard D
2018-05-18
Researchers and funders should consider the statistical power of planned Individual Participant Data (IPD) meta-analysis projects, as they are often time-consuming and costly. We propose simulation-based power calculations utilising a two-stage framework, and illustrate the approach for a planned IPD meta-analysis of randomised trials with continuous outcomes where the aim is to identify treatment-covariate interactions. The simulation approach has four steps: (i) specify an underlying (data generating) statistical model for trials in the IPD meta-analysis; (ii) use readily available information (e.g. from publications) and prior knowledge (e.g. number of studies promising IPD) to specify model parameter values (e.g. control group mean, intervention effect, treatment-covariate interaction); (iii) simulate an IPD meta-analysis dataset of a particular size from the model, and apply a two-stage IPD meta-analysis to obtain the summary estimate of interest (e.g. interaction effect) and its associated p-value; (iv) repeat the previous step (e.g. thousands of times), then estimate the power to detect a genuine effect by the proportion of summary estimates with a significant p-value. In a planned IPD meta-analysis of lifestyle interventions to reduce weight gain in pregnancy, 14 trials (1183 patients) promised their IPD to examine a treatment-BMI interaction (i.e. whether baseline BMI modifies intervention effect on weight gain). Using our simulation-based approach, a two-stage IPD meta-analysis has meta-analysis was appropriate. Pre-specified adjustment for prognostic factors would increase power further. Incorrect dichotomisation of BMI would reduce power by over 20%, similar to immediately throwing away IPD from ten trials. Simulation-based power calculations could inform the planning and funding of IPD projects, and should be used routinely.
Design and Strength Calculations of the Tripod Support Structure for Offshore Power Plant
Directory of Open Access Journals (Sweden)
Dymarski C.
2015-01-01
Full Text Available The support structure being the object of the analysis presented in the article is Tripod. According to the adopted assumptions, it is a foundation gravitationally set in the water region of 60 m in depth, not fixed to the seabed, which can be used for installing a 7MW wind turbine. Due to the lack of substantial information on designing and strength calculations of such types of structures in the world literature, authors have made an attempt to solve this problem within the framework of the abovementioned project. In the performed calculations all basic loads acting on the structure were taken into account, including: the self mass of the structure, the masses of the ballast, the tower and the turbine, as well as hydrostatic forces, and aero- and hydrodynamic forces acting on the entire object in extreme operating conditions.
Calculation of gas Bremsstrahlung power from straight sections of storage ring at SSRF
International Nuclear Information System (INIS)
Hua Zhengdong; Xu Xunjiang; Fang Keming; Xu Jiaqiang
2008-01-01
The Shanghai Synchrotron Radiation Facility (SSRF) is a third-generation synchrotron radiation light source with 3.5 GeV in energy, which is composed of the linear accelerator, the booster and the storage ring. The storage ring provides 16 standard straight sections of 6.5 m and 4 long straight sections of 12 meters. Gas Bremsstrahlung (GB) produced by the interaction of the stored beam with the residual gas molecules in straight section, which is so intense and has a very small angular that the GB spectra, the GB power and the GB power distribution should be known. The characters of GB are studied by means of Fluka Monte Carlo code. Our result shows agreement with those obtained by the experiential formulae. (authors)
Directory of Open Access Journals (Sweden)
Finch Stephen J
2005-04-01
Full Text Available Abstract Background Phenotype error causes reduction in power to detect genetic association. We present a quantification of phenotype error, also known as diagnostic error, on power and sample size calculations for case-control genetic association studies between a marker locus and a disease phenotype. We consider the classic Pearson chi-square test for independence as our test of genetic association. To determine asymptotic power analytically, we compute the distribution's non-centrality parameter, which is a function of the case and control sample sizes, genotype frequencies, disease prevalence, and phenotype misclassification probabilities. We derive the non-centrality parameter in the presence of phenotype errors and equivalent formulas for misclassification cost (the percentage increase in minimum sample size needed to maintain constant asymptotic power at a fixed significance level for each percentage increase in a given misclassification parameter. We use a linear Taylor Series approximation for the cost of phenotype misclassification to determine lower bounds for the relative costs of misclassifying a true affected (respectively, unaffected as a control (respectively, case. Power is verified by computer simulation. Results Our major findings are that: (i the median absolute difference between analytic power with our method and simulation power was 0.001 and the absolute difference was no larger than 0.011; (ii as the disease prevalence approaches 0, the cost of misclassifying a unaffected as a case becomes infinitely large while the cost of misclassifying an affected as a control approaches 0. Conclusion Our work enables researchers to specifically quantify power loss and minimum sample size requirements in the presence of phenotype errors, thereby allowing for more realistic study design. For most diseases of current interest, verifying that cases are correctly classified is of paramount importance.
2012-08-01
regenerative braking or simulated engine braking . AVL Hybrid Control System (HCU) coordinates and controls all system components as laid out in Figure... regenerative and friction brakes with a 34% dead-band on the brake pedal. Table 2 gives a summary and comparison of simulation results in terms of kg of...2012 NDIA GROUND VEHICLE SYSTEMS ENGINEERING AND TECHNOLOGY SYMPOSIUM POWER AND MOBILITY (P&M) MINI-SYMPOSIUM AUGUST 14-16, MICHIGAN AN
The control-and-instrumentation system of the IEA zero power reactor and its reliability calculation
International Nuclear Information System (INIS)
Peluso, M.A.V.
1978-01-01
The control-and instrumentation system for the Instituto de Energia Atomica Zero Power Reactor is described and the design criteria are presented and discussed. The reliability analysis for the reactor protection system was performed using the fault tree method. This was done using a computer code based on the Monte Carlo simulation. That code is an adaptation of the SAFTE-I, for the IBM 360/155 IEA Computer. (Author) [pt
Lens Ray Diagrams with a Spreadsheet
González, Manuel I.
2018-01-01
Physicists create spreadsheets customarily to carry out numerical calculations and to display their results in a meaningful, nice-looking way. Spreadsheets can also be used to display a vivid geometrical model of a physical system. This statement is illustrated with an example taken from geometrical optics: images formed by a thin lens. A careful…
Full Text Available ... One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume ... Costume Contact Lenses Can Ruin Vision Eye Makeup Safety In fact, it is illegal to sell colored ...
Full Text Available ... One Use Facts About Colored Contacts and Halloween Safety Colored Contact Lens Facts Over-the-Counter Costume ... new application of artificial intelligence shows whether a patient’s eyes point to high blood pressure or risk ...
Matthews, Andrew G
2004-08-01
It is conservatively estimated that some form of lens opacity is present in 5% to 7% of horses with otherwise clinically normal eyes.These opacities can range from small epicapsular remnants of the fetal vasculature to dense and extensive cataract. A cataract is defined technically as any opacity or alteration in the optical homogeneity of the lens involving one or more of the following: anterior epithelium, capsule, cortex, or nucleus. In the horse, cataracts rarely involve the entire lens structure (ie, complete cataracts) and are more usually localized to one anatomic landmark or sector of the lens. Complete cataracts are invariably associated with overt and significant visual disability. Focal or incomplete cataracts alone seldom cause any apparent visual dysfunction in affected horses,however.
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Collisional-radiative switching - A powerful technique for converging non-LTE calculations
Hummer, D. G.; Voels, S. A.
1988-01-01
A very simple technique has been developed to converge statistical equilibrium and model atmospheric calculations in extreme non-LTE conditions when the usual iterative methods fail to converge from an LTE starting model. The proposed technique is based on a smooth transition from a collision-dominated LTE situation to the desired non-LTE conditions in which radiation dominates, at least in the most important transitions. The proposed approach was used to successfully compute stellar models with He abundances of 0.20, 0.30, and 0.50; Teff = 30,000 K, and log g = 2.9.
Graph theoretical models for calculating the reliablility of power plants. Pt. 4
International Nuclear Information System (INIS)
Vetterkind, D.W.
1978-01-01
With the aid of mathematical formalisms from the theory of stochastical networks, approximation equations are derived for the expectation value as well as for the scattering of period-related availability of series systems consisting of deteriorating and/or non-deteriorating components. In this context, successive operating times of deteriorating components are described by the time-dependent Poisson process while successive operating times of non-deteriorating components are described by the time-independent Poisson process. In addition provision is made in the model to include in the calculation an existing trend of the expectation value of components successive failure times. (orig./RW) [de
Calculating Nuclear Power Plant Vulnerability Using Integrated Geometry and Event/Fault-Tree Models
International Nuclear Information System (INIS)
Peplow, Douglas E.; Sulfredge, C. David; Sanders, Robert L.; Morris, Robert H.; Hann, Todd A.
2004-01-01
Since the events of September 11, 2001, the vulnerability of nuclear power plants to terrorist attacks has become a national concern. The results of vulnerability analysis are greatly influenced by the computational approaches used. Standard approximations used in fault-tree analysis are not applicable for attacks, where high component failure probabilities are expected; two methods that do work with high failure probabilities are presented. Different blast modeling approaches can also affect the end results. Modeling the structural details of facility buildings and the geometric layout of components within the buildings is required to yield meaningful results
A method to calculate the effect of heterogeneous composition on bundle power
Energy Technology Data Exchange (ETDEWEB)
Choi, Hang Bok [Korea Atomic Energy Research Institute, Taejon (Korea)
1998-09-01
In the DUPIC fuel cycle, the spent pressurized water reactor (PWR) fuel is used in a Canada deuterium uranium (CANDU) reactor. Depending on the initial condition and burnup history of PWR fuel, the DUPIC fuel composition varies accordingly. In order to see the effect of the fuel composition, a simple and fast method was developed and applied to the DUPIC fuel. This report discusses the method developed to predict the effect of heterogeneous fuel composition on the bundle power. (author). 3 refs., 5 tabs.
Calculation of the optimum fuel distribution which maximizes the power output of a reactor
International Nuclear Information System (INIS)
Santos, W.N. dos.
1979-01-01
Using optimal control techniques, the optimum fuel distribution - which maximizes the power output of a thermal reactor - is obtained. The nuclear reactor is described by a diffusion theory model with four energy groups and by assuming plane geometry. Since the analytical solution is impracticable, by using a perturbation method, a FORTRAN program was written, in order to obtain the numerical solution. Numerical results, for a thermal reactor light water moderated, non reflected, are shown. The fissile fuel material considered is Uranium-235. (Author) [pt
Maceo Heilman, Bianca; Manns, Fabrice; de Castro, Alberto; Durkee, Heather; Arrieta, Esdras; Marcos, Susana; Parel, Jean-Marie
2015-02-10
The purpose of this study was to quantify accommodation-induced changes in the spherical aberration of cynomolgus monkey lenses. Twenty-four lenses from 20 cynomolgus monkeys (Macaca fascicularis; 4.4-16.0 years of age; postmortem time 13.5 ± 13.0 hours) were mounted in a lens stretcher. Lens spherical aberration was measured in the unstretched (accommodated) and stretched (relaxed) states with a laser ray tracing system that delivered 51 equally spaced parallel rays along 1 meridian of the lens over the central 6-mm optical zone. A camera mounted below the lens was used to measure the ray height at multiple positions along the optical axis. For each entrance ray, the change in ray height with axial position was fitted with a third-order polynomial. The effective paraxial focal length and Zernike spherical aberration coefficients corresponding to a 6-mm pupil diameter were extracted from the fitted values. The unstretched lens power decreased with age from 59.3 ± 4.0 diopters (D) for young lenses to 45.7 ± 3.1 D for older lenses. The unstretched lens shifted toward less negative spherical aberration with age, from -6.3 ± 0.7 μm for young lenses to -5.0 ± 0.5 μm for older lenses. The power and spherical aberration of lenses in the stretched state were independent of age, with values of 33.5 ± 3.4 D and -2.6 ± 0.5 μm, respectively. Spherical aberration is negative in cynomolgus monkey lenses and becomes more negative with accommodation. These results are in good agreement with the predicted values using computational ray tracing in a lens model with a reconstructed gradient refractive index. The spherical aberration of the unstretched lens becomes less negative with age. Copyright 2015 The Association for Research in Vision and Ophthalmology, Inc.
In vivo Comet assay – statistical analysis and power calculations of mice testicular cells
DEFF Research Database (Denmark)
Hansen, Merete Kjær; Sharma, Anoop Kumar; Dybdahl, Marianne
2014-01-01
is to provide curves for this statistic outlining the number of animals and gels to use. The current study was based on 11 compounds administered via oral gavage in three doses to male mice: CAS no. 110-26-9, CAS no. 512-56-1, CAS no. 111873-33-7, CAS no. 79-94-7, CAS no. 115-96-8, CAS no. 598-55-0, CAS no. 636....... A linear mixed-effects model was fitted to the summarized data and the estimated variance components were used to generate power curves as a function of sample size. The statistic that most appropriately summarized the within-sample distributions was the median of the log-transformed data, as it most...... consistently conformed to the assumptions of the statistical model. Power curves for 1.5-, 2-, and 2.5-fold changes of the highest dose group compared to the control group when 50 and 100 cells were scored per gel are provided to aid in the design of future Comet assay studies on testicular cells....
International Nuclear Information System (INIS)
Xu, Liang; Yuan, Jingqi
2015-01-01
Thermodynamic properties of the working fluid and the flue gas play an important role in the thermodynamic calculation for the boiler design and the operational optimization in power plants. In this study, a generic approach to online calculate the thermodynamic properties of the flue gas is proposed based on its composition estimation. It covers the full operation scope of the flue gas, including the two-phase state when the temperature becomes lower than the dew point. The composition of the flue gas is online estimated based on the routinely offline assays of the coal samples and the online measured oxygen mole fraction in the flue gas. The relative error of the proposed approach is found less than 1% when the standard data set of the dry and humid air and the typical flue gas is used for validation. Also, the sensitivity analysis of the individual component and the influence of the measurement error of the oxygen mole fraction on the thermodynamic properties of the flue gas are presented. - Highlights: • Flue gas thermodynamic properties in coal-fired power plants are online calculated. • Flue gas composition is online estimated using the measured oxygen mole fraction. • The proposed approach covers full operation scope, including two-phase flue gas. • Component sensitivity to the thermodynamic properties of flue gas is presented.
International Nuclear Information System (INIS)
Nguyen Tuan Khai; Hoang Van Khanh; Phan Quoc Vuong; Tran Viet Phu; Tran Vinh Thanh; Nguyen Thi Mai Huong; Nguyen Thi Dung; Le Tran Chung; Nguyen Minh Tuan; Tran Quoc Duong
2014-01-01
The project aims at nuclear human resource development and enhancement in research capability in reactor physics and kinetics at Nuclear Energy Center (Institute for Nuclear Science and Technology) and Nuclear Reactor Center (Nuclear Research Institute, Dalat). The main research items of the project can be summarized as follows: i) Considering possibility on using modern calculation techniques and methods in investigating neutronic characteristics and neutronics-thermal hydraulics coupling. This item is proposed to carry out based on international collaboration with Prof. Le Trong Thuy, San Jose University, US; ii) Carrying out the collaborative activities in research and training between Nuclear Energy Center (Institute for Nuclear Science and Technology) and Nuclear Reactor Center (Nuclear Research Institute, Dalat); iii) Opening two-week training course on nuclear reactor engineering (25 Nov - 12 Dec 2013) in collaboration with Japan Atomic Energy Agency (JAEA). (author)
Energy Technology Data Exchange (ETDEWEB)
Sher, R. [Rudolph Sher Associates, Stanford, CA (United States); Li, J. [Polestar Applied Technology, Inc., Los Altos, CA (United States)
1995-02-01
NAUAHYGROS is a computer code to calculate the behavior of fission product and other aerosol particles in the containment of a nuclear reactor following a severe accident. It is an extension of the German code NAUA, which has been in widespread use for many years. Early versions of NAUA treated various aerosol phenomena in dry atmospheres, including aerosol agglomeration, diffusion (plateout), and settling processes. Later versions added treatments of steam condensation on particles in saturated or supersaturated containment atmospheres. The importance of these condensation effects on aerosol removal rates was demonstrated in large scale simulated containment tests. The additional features incorporated in NAUAHYGROS include principally a treatment of steam condensation on hygroscopic aerosols, which can grow as a result of steam condensation even in superheated atmospheres, and improved modelling of steam condensation on the walls of the containment. The code has been validated against the LACE experiments.
International Nuclear Information System (INIS)
Dorning, J.J.
1991-01-01
A simultaneous pin lattice cell and fuel bundle homogenization theory has been developed for use with nodal diffusion calculations of practical reactors. The theoretical development of the homogenization theory, which is based on multiple-scales asymptotic expansion methods carried out through fourth order in a small parameter, starts from the transport equation and systematically yields: a cell-homogenized bundled diffusion equation with self-consistent expressions for the cell-homogenized cross sections and diffusion tensor elements; and a bundle-homogenized global reactor diffusion equation with self-consistent expressions for the bundle-homogenized cross sections and diffusion tensor elements. The continuity of the angular flux at cell and bundle interfaces also systematically yields jump conditions for the scaler flux or so-called flux discontinuity factors on the cell and bundle interfaces in terms of the two adjacent cell or bundle eigenfunctions. The expressions required for the reconstruction of the angular flux or the 'de-homogenization' theory were obtained as an integral part of the development; hence the leading order transport theory angular flux is easily reconstructed throughout the reactor including the regions in the interior of the fuel bundles or computational nodes and in the interiors of the pin lattice cells. The theoretical development shows that the exact transport theory angular flux is obtained to first order from the whole-reactor nodal diffusion calculations, done using the homogenized nuclear data and discontinuity factors, is a product of three computed quantities: a ''cell shape function''; a ''bundle shape function''; and a ''global shape function''. 10 refs
International Nuclear Information System (INIS)
Mosteller, R.D.; Hall, R.A.; Lancaster, D.B.; Young, E.H.; Gavin, P.H.; Robertson, S.T.
1998-01-01
The contents of ANS 19.11, the standard for ''Calculation and Measurement of the Moderator Temperature Coefficient of Reactivity in Water-Moderated Power Reactors,'' are described. The standard addresses the calculation of the moderator temperature coefficient (MTC) both at standby conditions and at power. In addition, it describes several methods for the measurement of the at-power MTC and assesses their relative advantages and disadvantages. Finally, it specifies a minimum set of documentation requirements for compliance with the standard
International Nuclear Information System (INIS)
Fernandez-Varea, J.M.; Mayol, R.; Salvat, F.; Liljequist, D.
1992-11-01
The numerical calculation of electron inelastic mean free path and stopping power from an optical-data model recently proposed by Fernandez-Varea et al. is described in detail. Explicit expressions for the one-electron total cross sections of the two-modes model of the free-electron gas and the δ-oscillator are derived. The inelastic mean free path and the stopping power are obtained as integrals of these one-electron total cross sections weighted by the optical as integrals of these one-electron total cross sections weighted by the optical oscillator strength. The integrals can be easily evaluated, with a selected accuracy, by using the FORTRAN 77 subroutine GABQ described here, which implements a 20-points Gauss adaptive bipartition quadrature method. Source listings of FORTRAN 77 subroutines to compute the one-electron total cross sections are also given
Terahertz lens made out of natural stone.
Han, Daehoon; Lee, Kanghee; Lim, Jongseok; Hong, Sei Sun; Kim, Young Kie; Ahn, Jaewook
2013-12-20
Terahertz (THz) time-domain spectroscopy probes the optical properties of naturally occurring solid aggregates of minerals, or stones, in the THz frequency range. Refractive index and extinction coefficient measurement reveals that most natural stones, including mudstone, sandstone, granite, tuff, gneiss, diorite, slate, marble, and dolomite, are fairly transparent for THz frequency waves. Dolomite in particular exhibits a nearly uniform refractive index of 2.7 over the broad frequency range from 0.1 to 1 THz. The high index of refraction allows flexibility in lens designing with a shorter accessible focal length or a thinner lens with a given focal length. Good agreement between the experiment and calculation for the THz beam profile confirms that dolomite has high homogeneity as a lens material, suggesting the possibility of using natural stones for THz optical elements.
International Nuclear Information System (INIS)
Chen Fubing; Dong Yujie; Zheng Yanhua; Shi Lei; Zhang Zuoyi
2009-01-01
Within the framework of a Coordinated Research Project on Evaluation of High Temperature Gas-Cooled Reactor Performance (CRP-5) initiated by the International Atomic Energy Agency (IAEA), the calculation of steady-state temperature distribution of the 10 MW High Temperature Gas-Cooled Reactor-Test Module (HTR-10) under its initial full power experimental operation has been defined as one of the benchmark problems. This paper gives the investigation results obtained by different countries who participate in solving this benchmark problem. The validation works of the THERMIX code used by the Institute of Nuclear and New Energy Technology (INET) are also presented. For the benchmark items defined in this CRP, various calculation results correspond well with each other and basically agree the experimental results. Discrepancies existing among various code results are preliminarily attributed to different methods, models, material properties, and so on used in the computations. Temperatures calculated by THERMIX for the measuring points in the reactor internals agree well with the experimental values. The maximum fuel center temperatures calculated by the participants are much lower than the limited value of 1,230degC. According to the comparison results of code-to-code as well as code-to-experiment, THERMIX is considered to reproduce relatively satisfactory results for the CRP-5 benchmark problem. (author)
Energy Technology Data Exchange (ETDEWEB)
Anderson, D W
1973-04-15
Assessments of the ability of UK methods and data developed primarily for the low enriched uranium cycle to simulate thorium cycle HTRs haye been extended to cover reactivity and power distributions in commercial size reactors. The Fort St. Vrain 330 MW(E) HTR being built in the United States by Gulf General Atomic has been chosen as a convenient object for such a study since detailed design information together with the results of GGA's own calculations have been published. The results obtained are in good agreement with those obtained by GGA and indicate that both thorium and low enriched cycle HTRs can be adequately modelled with UK data and methods.
In vivo Comet assay--statistical analysis and power calculations of mice testicular cells.
Hansen, Merete Kjær; Sharma, Anoop Kumar; Dybdahl, Marianne; Boberg, Julie; Kulahci, Murat
2014-11-01
The in vivo Comet assay is a sensitive method for evaluating DNA damage. A recurrent concern is how to analyze the data appropriately and efficiently. A popular approach is to summarize the raw data into a summary statistic prior to the statistical analysis. However, consensus on which summary statistic to use has yet to be reached. Another important consideration concerns the assessment of proper sample sizes in the design of Comet assay studies. This study aims to identify a statistic suitably summarizing the % tail DNA of mice testicular samples in Comet assay studies. A second aim is to provide curves for this statistic outlining the number of animals and gels to use. The current study was based on 11 compounds administered via oral gavage in three doses to male mice: CAS no. 110-26-9, CAS no. 512-56-1, CAS no. 111873-33-7, CAS no. 79-94-7, CAS no. 115-96-8, CAS no. 598-55-0, CAS no. 636-97-5, CAS no. 85-28-9, CAS no. 13674-87-8, CAS no. 43100-38-5 and CAS no. 60965-26-6. Testicular cells were examined using the alkaline version of the Comet assay and the DNA damage was quantified as % tail DNA using a fully automatic scoring system. From the raw data 23 summary statistics were examined. A linear mixed-effects model was fitted to the summarized data and the estimated variance components were used to generate power curves as a function of sample size. The statistic that most appropriately summarized the within-sample distributions was the median of the log-transformed data, as it most consistently conformed to the assumptions of the statistical model. Power curves for 1.5-, 2-, and 2.5-fold changes of the highest dose group compared to the control group when 50 and 100 cells were scored per gel are provided to aid in the design of future Comet assay studies on testicular cells. Copyright © 2014 Elsevier B.V. All rights reserved.
Calculation of DPA in the Reactor Internal Structural Materials of Nuclear Power Plant
International Nuclear Information System (INIS)
Kim, Yong Deong; Lee, Hwan Soo
2014-01-01
The embrittlement is mainly caused by atomic displacement damage due to irradiations with neutrons, especially fast neutrons. The integrity of the reactor internal structural materials has to be ensured over the reactor life time, threatened by the irradiation induced displacement damage. Accurate modeling and prediction of the displacement damage is a first step to evaluate the integrity of the reactor internal structural materials. Traditional approaches for analyzing the displacement damage of the materials have relied on tradition model, developed initially for simple metals, Kinchin and Pease (K-P), and the standard formulation of it by Norgett et al. , often referred to as the 'NRT' model. An alternative and complementary strategy for calculating the displacement damage is to use MCNP code. MCNP uses detailed physics and continuous-energy cross-section data in its simulations. In this paper, we have performed the evaluation of the displacement damage of the reactor internal structural materials in Kori NPP unit 1 using detailed Monte Carlo modeling and compared with predictions results of displacement damage using the classical NRT model. The evaluation of the displacement damage of the reactor internal structural materials in Kori NPP unit 1 using detailed Monte Carlo modeling has been performed. The maximum value of the DPA rate was occurred at the baffle side of the reactor internal where the node has the maximum neutron flux
Energy Technology Data Exchange (ETDEWEB)
Voigt, B
1982-02-19
The possibilities are shown how input parameters are determined for reliability computations. This is done for the components of a transmission system and the evaluated failure statistics of an electric utility company. The following parameters of high interest to reliability engineering are treated: dependence of the failure frequency on the system's cable length, distribution of failure intervals of cables with different voltage levels, followerd by a study of influencing variables due to daily or seasonal fluctuations. Possibilities are pointed out of computing the system reliability on the basis of component parameters, and a method is presented that can be applied in the planning stage as well as during operation of energy transmission systems. Finally, the calculation of a real sub-net of a given energy supply is presented. The methodology of fault-tree analysis, implemented in several, different computer programs, is the input parameter of this section. This method is applied to determine minimum interface structures of a system, to simulating the TOP event in the fault tree and, in the method presented here, to determining the structural significance of components within a system.
International Nuclear Information System (INIS)
Ueki, Taro
2010-01-01
The noise propagation of tallies in the Monte Carlo power method can be represented by the autoregressive moving average process of orders p and p-1 (ARMA(p,p-1)], where p is an integer larger than or equal to two. The formula of the autocorrelation of ARMA(p,q), p≥q+1, indicates that ARMA(3,2) fitting is equivalent to lumping the eigenmodes of fluctuation propagation in three modes such as the slow, intermediate and fast attenuation modes. Therefore, ARMA(3,2) fitting was applied to the real standard deviation estimation of fuel assemblies at particular heights. The numerical results show that straightforward ARMA(3,2) fitting is promising but a stability issue must be resolved toward the incorporation in the distributed version of production Monte Carlo codes. The same numerical results reveal that the average performance of ARMA(3,2) fitting is equivalent to that of the batch method in MCNP with a batch size larger than one hundred and smaller than two hundred cycles for a 1100 MWe pressurized water reactor. The bias correction of low lag autocovariances in MVP/GMVP is demonstrated to have the potential of improving the average performance of ARMA(3,2) fitting. (author)
On different types of adjustment usable to calculate the parameters of the stream power law
Demoulin, Alain; Beckers, Arnaud; Bovy, Benoît
2012-02-01
Model parameterization through adjustment to field data is a crucial step in the modeling and the understanding of the drainage network response to tectonic or climatic perturbations. Using as a test case a data set of 18 knickpoints that materialize the migration of a 0.7-Ma-old erosion wave in the Ourthe catchment of northern Ardennes (western Europe), we explore the impact of various data fitting on the calibration of the stream power model of river incision, from which a simple knickpoint celerity equation is derived. Our results show that statistical least squares adjustments (or misfit functions) based either on the stream-wise distances between observed and modeled knickpoint positions at time t or on differences between observed and modeled time at the actual knickpoint locations yield significantly different values for the m and K parameters of the model. As there is no physical reason to prefer one of these approaches, an intermediate least-rectangles adjustment might at first glance appear as the best compromise. However, the statistics of the analysis of 200 sets of synthetic knickpoints generated in the Ourthe catchment indicate that the time-based adjustment is the most capable of getting close to the true parameter values. Moreover, this fitting method leads in all cases to an m value lower than that obtained from the classical distance adjustment (for example, 0.75 against 0.86 for the real case of the Ourthe catchment), corresponding to an increase in the non-linear character of the dependence of knickpoint celerity on discharge.
Energy Technology Data Exchange (ETDEWEB)
Nasrazadani, Zahra; Salimi, Raana; Askari, Afrooz; Khorsandi, Jamshid; Mirvakili, Mohammad; Mashayekh, Mohammad [Reactor Research School, Nuclear Science and Technology Research Institute, Atomic Energy Organization of Iran, Esfahan (Iran, Islamic Republic of)
2017-02-15
The heavy water zero power reactor (HWZPR), which is a critical assembly with a maximum power of 100 W, can be used in different lattice pitches. The last change of core configuration was from a lattice pitch of 18-20 cm. Based on regulations, prior to the first operation of the reactor, a new core was simulated with MCNP (Monte Carlo N-Particle)-4C and WIMS (Winfrith Improved Multigroup Scheme)-CITATON codes. To investigate the criticality of this core, the effective multiplication factor (Keff) versus heavy water level, and the critical water level were calculated. Then, for safety considerations, the reactivity worth of D2O, the reactivity worth of safety and control rods, and temperature reactivity coefficients for the fuel and the moderator, were calculated. The results show that the relevant criteria in the safety analysis report were satisfied in the new core. Therefore, with the permission of the reactor safety committee, the first criticality operation was conducted, and important physical parameters were measured experimentally. The results were compared with the corresponding values in the original core.
Lim, Julie C; Vaghefi, Ehsan; Li, Bo; Nye-Wood, Mitchell G; Donaldson, Paul J
2016-04-01
To assess the morphologic, biochemical, and optical properties of bovine lenses treated with hyperbaric oxygen. Lenses were exposed to hyperbaric nitrogen (HBN) or hyperbaric oxygen (HBO) for 5 or 15 hours, lens transparency was assessed using bright field microscopy and lens morphology was visualized using confocal microscopy. Lenses were dissected into the outer cortex, inner cortex, and core, and glutathione (GSH) and malondialdehyde (MDA) measured. Gel electrophoresis and Western blotting were used to detect high molecular weight aggregates (HMW) and glutathione mixed protein disulfides (PSSG). T2-weighted MRI was used to measure lens geometry and map the water/protein ratio to allow gradient refractive index (GRIN) profiles to be calculated. Optical modeling software calculated the change in lens optical power, and an anatomically correct model of the light pathway of the bovine eye was used to determine the effects of HBN and HBO on focal length and overall image quality. Lenses were transparent and lens morphology similar between HBN- and HBO-treated lenses. At 5- and 15-hour HBO exposure, GSH and GSSG were depleted and MDA increased in the core. Glutathione mixed protein disulfides were detected in the outer and inner cortex only with no appearance of HMW. Optical changes were detectable only with 15-hour HBO treatment with a decrease in the refractive index of the core, slightly reduced lens thickness, and an increase in optimal focal length, consistent with a hyperopic shift. This system may serve as a model to study changes that occur with advanced aging rather than nuclear cataract formation per se.
Composite modified Luneburg model of human eye lens.
Gómez-Correa, J E; Balderas-Mata, S E; Pierscionek, B K; Chávez-Cerda, S
2015-09-01
A new lens model based on the gradient-index Luneburg lens and composed of two oblate half spheroids of different curvatures is presented. The spherically symmetric Luneburg lens is modified to create continuous isoindicial contours and to incorporate curvatures that are similar to those found in a human lens. The imaging capabilities of the model and the changes in the gradient index profile are tested for five object distances, for a fixed geometry and for a fixed image distance. The central refractive index decreases with decreasing object distance. This indicates that in order to focus at the same image distance as is required in the eye, a decrease in refractive power is needed for rays from closer objects that meet the lens surface at steeper angles compared to rays from more distant objects. This ensures a highly focused image with no spherical aberration.
International Nuclear Information System (INIS)
Toshio, S.; Kazuo, A.
1983-01-01
A model for calculating the power distribution and the control rod worth in fast reactors has been developed. This model is based on the influence function method. The characteristics of the model are as follows: 1. Influence functions for any changes in the control rod insertion ratio are expressed by using an influence function for an appropriate control rod insertion in order to reduce the computer memory size required for the method. 2. A control rod worth is calculated on the basis of a one-group approximation in which cross sections are generated by bilinear (flux-adjoint) weighting, not the usual flux weighting, in order to reduce the collapse error. 3. An effective neutron multiplication factor is calculated by adjoint weighting in order to reduce the effect of the error in the one-group flux distribution. The results obtained in numerical examinations of a prototype fast reactor indicate that this method is suitable for on-line core performance evaluation because of a short computing time and a small memory size
International Nuclear Information System (INIS)
Sanda, T.; Azekura, K.
1983-01-01
A model for calculating the power distribution and the control rod worth in fast reactors has been developed. This model is based on the influence function method. The characteristics of the model are as follows: Influence functions for any changes in the control rod insertion ratio are expressed by using an influence function for an appropriate control rod insertion in order to reduce the computer memory size required for the method. A control rod worth is calculated on the basis of a one-group approximation in which cross sections are generated by bilinear (flux-adjoint) weighting, not the usual flux weighting, in order to reduce the collapse error. An effective neutron multiplication factor is calculated by adjoint weighting in order to reduce the effect of the error in the one-group flux distribution. The results obtained in numerical examinations of a prototype fast reactor indicate that this method is suitable for on-line core performance evaluation because of a short computing time and a small memory size
International Nuclear Information System (INIS)
Namestek, L.; Khorvat, D; Shvets, J.; Kunz, Eh.
1976-01-01
A method of calculating the doses of external and internal person irradiation in the nuclear power plant vicinity under conditions of normal operation and accident situations has been described. The main difference between the above method and methods used up to now is the use of a new antropomorphous representation of a human body model together with all the organs. The antropomorphous model of human body and its organs is determined as a set of simple solids, coordinates of disposistion of the solids, sizes, masses, densities and composition corresponding the genuine organs. The use of the Monte-Carlo method is the second difference. The results of the calculations according to the model suggested can be used for determination: a critical group of inhabitans under conditions of normal plant operation; groups of inhabitants most subjected to irradiation in the case of possible accident; a critical sector with a maximum collective dose in the case of an accident; a critical radioisotope favouring the greatest contribution to an individual equivalent dose; critical irradiation ways promoting a maximum contribution to individual equivalent doses; cumulative collective doses for the whole region or for a chosen part of the region permitting to estimate a population dose. The consequent method evoluation suggests the development of separate units of the calculationg program, critical application and the selection of input data of physical, plysiological and ecological character and improvement of the calculated program for the separate concrete events [ru
Symmetric lens with extended depth of focus
Cho, Sung Nae
2008-01-01
The lens surface profile is derived based on the instantaneous focal length versus the lens radius data. The lens design based on instantaneous focal length versus the lens radius data has many useful applications in software assisted image focusing technology.
Frequency Invariant Beam Steering for Short-Pulse Systems with a Rotman Lens
Directory of Open Access Journals (Sweden)
Andreas Lambrecht
2010-01-01
Full Text Available A promising approach for beam steering of high-voltage transient signals for HPEM-systems (High Power Electro Magnetic is presented. The inherent capability of the Rotman lens to provide true time delays is used to develop a prototype beam steering device for an antielectronics HPEM system in the frequency range from 350 MHz to 5 GHz. Results of analytical calculations, simulations, and measurements from a hardware prototype are presented. The detailed mechanical setup of the Rotman lens is presented. Additionally the output pulses are investigated when inputting a Gaussian-like transient signal. Then time domain measures of quality (full width at half maximum, ringing, delay spread, maximum of transfer function are investigated for these output transients, and the simulation and measurement results are compared. A concluding analysis of the realizable time domain array pattern shows the radiated pulse form.
International Nuclear Information System (INIS)
Rambauske, W.R.
1973-01-01
The invention relates to a catoptric lens for combining energies transmitted by several sources such as lasers; said lens comprising mirrors, the reflective surfaces of which have their focuses spaced from a common axis of symmetry. By means of these reflecting surfaces, which are generated by the nutation of portions of quadratic conics about the axis of symmetry, it is possible to focus the energy emmited by several lasers at the focus of the exit-mirror reflecting surface. This can be applied to thermonuclear fusion [fr
Bacterial adhesion forces to Ag-impregnated contact lens cases and transmission to contact lenses.
Qu, Wenwen; Busscher, Henk J; van der Mei, Henny C; Hooymans, Johanna M M
2013-03-01
To measure adhesion forces of Pseudomonas aeruginosa, Staphylococcus aureus, and Serratia marcescens to a rigid contact lens (CL), standard polypropylene, and Ag-impregnated lens cases using atomic force microscopy and determine bacterial transmission from lens case to CL. Adhesion forces of bacterial strains to Ag-impregnated and polypropylene lens cases and a rigid CL were measured using atomic force microscopy. Adhesion forces were used to calculate Weibull distributions, from which transmission probabilities from lens case to CL were derived. Transmission probabilities were compared with actual transmission of viable bacteria from a lens case to the CL in 0.9% NaCl and in an antimicrobial lens care solution. Bacterial transmission probabilities from polypropylene lens cases based on force analysis coincided well for all strains with actual transmission in 0.9% NaCl. Bacterial adhesion forces on Ag-impregnated lens cases were much smaller than that on polypropylene and CLs, yielding a high probability of transmission. Comparison with actual bacterial transmission indicated bacterial killing due to Ag ions during colony-forming unit transmission from an Ag-impregnated lens case, especially for P. aeruginosa. Transmission of viable bacteria from Ag-impregnated lens cases could be further decreased by use of an antimicrobial lens care solution instead of 0.9% NaCl. Bacterial transmission probabilities are higher from Ag-impregnated lens cases than from polypropylene lens cases because of small adhesion forces, but this is compensated for by enhanced bacterial killing due to Ag impregnation, especially when in combination with an antimicrobial lens care solution. This calls for a balanced combination of antimicrobial lens care solutions and surface properties of a lens case and CL.
Effect of contact lens use on Computer Vision Syndrome.
Tauste, Ana; Ronda, Elena; Molina, María-José; Seguí, Mar
2016-03-01
To analyse the relationship between Computer Vision Syndrome (CVS) in computer workers and contact lens use, according to lens materials. Cross-sectional study. The study included 426 civil-service office workers, of whom 22% were contact lens wearers. Workers completed the Computer Vision Syndrome Questionnaire (CVS-Q) and provided information on their contact lenses and exposure to video display terminals (VDT) at work. CVS was defined as a CVS-Q score of 6 or more. The covariates were age and sex. Logistic regression was used to calculate the association (crude and adjusted for age and sex) between CVS and individual and work-related factors, and between CVS and contact lens type. Contact lens wearers are more likely to suffer CVS than non-lens wearers, with a prevalence of 65% vs 50%. Workers who wear contact lenses and are exposed to the computer for more than 6 h day(-1) are more likely to suffer CVS than non-lens wearers working at the computer for the same amount of time (aOR = 4.85; 95% CI, 1.25-18.80; p = 0.02). Regular contact lens use increases CVS after 6 h of computer work. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.
International Nuclear Information System (INIS)
Kim, H. Y.; Joo, H. G.; Kim, K. S.; Kim, G. Y.; Jang, M. H.
2003-01-01
The reactivity and power distribution errors of the HELIOS/MASTER core calculation under power generating conditions are assessed using a whole core transport code DeCART. For this work, the cross section tablesets were generated for a medium sized PWR following the standard procedure and two group nodal core calculations were performed. The test cases include the HELIOS calculations for 2-D assemblies at constant thermal conditions, MASTER 3D assembly calculations at power generating conditions, and the core calculations at HZP, HFP, and an abnormal power conditions. In all these cases, the results of the DeCART code in which pinwise thermal feedback effects are incorporated are used as the reference. The core reactivity, assemblywise power distribution, axial power distribution, peaking factor, and thermal feedback effects are then compared. The comparison shows that the error of the HELIOS/MASTER system in the core reactivity, assembly wise power distribution, pin peaking factor are only 100∼300 pcm, 3%, and 2%, respectively. As far as the detailed pinwise power distribution is concerned, however, errors greater than 15% are observed
Tomlinson, Sally
2010-01-01
This article constitutes a short personal tribute to Len Barton in honour of his work and our collegial relationship going back over 30 years. It covers how Len saw his intellectual project of providing critical sociological and political perspectives on special education, disability and inclusion, and his own radical political perspectives. Len's…
Luneburg lens in silicon photonics.
Di Falco, Andrea; Kehr, Susanne C; Leonhardt, Ulf
2011-03-14
The Luneburg lens is an aberration-free lens that focuses light from all directions equally well. We fabricated and tested a Luneburg lens in silicon photonics. Such fully-integrated lenses may become the building blocks of compact Fourier optics on chips. Furthermore, our fabrication technique is sufficiently versatile for making perfect imaging devices on silicon platforms.
TU-E-201-01: Methods for Eye Lens Dosimetry and Studies On Lens Opacities with Interventionists
Energy Technology Data Exchange (ETDEWEB)
Rehani, M. [Massachusetts General Hospital (United States)
2015-06-15
. These actions should be considered when they are consistent with the clinical task and patient anatomy. Learning Objectives: To become familiar with method of eye dose estimation for patient in specific situation of brain perfusion CT To become familiar with level of eye lens radiation doses in patients undergoing brain perfusion MDCT To understand methods for reducing eye lens dose to patient Jong Min Park, Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea Eye lens dosimetry in radiotherapy using contact lens-shaped applicator Dose calculation accuracy of commercial treatment planning systems is relatively low at shallow depths. Therefore, in-vivo measurements are often performed in the clinic to verify delivered doses to eye lens which are located at shallow depth. Current in-vivo dosimetry for eye lens during radiotherapy is generally performed with small in-vivo dosimeters on the surface of patient eyelid. Since this procedure potentially contains considerable uncertainty, a contact lens-shaped applicator made of acrylic (lens applicator) was developed for in-vivo measurements of eye lens dose during radiotherapy to reduce uncertainty. The lens applicator allows the insertion of commercially available metal oxide semiconductor field effect transistor (MOSFET) dosimeters. Computed tomography (CT) images of an anthropomorphic phantom with and without the lens applicator were acquired. A total of 20 VMAT plans were delivered to an anthropomorphic phantom and the doses with the lens applicator and the doses at the surface of the eyelid were measured using both micro and standard MOSFET dosimeters. The differences in measured dose at the surface of the eyelid from the calculated lens dose were acquired. The differences between the measured and the calculated doses at the lens applicator, as well as the differences between the measured and the calculated doses at the surface of the eyelid were acquired. The statistical significance of the
TU-E-201-03: Eye Lens Dosimetry in Radiotherapy Using Contact Lens-Shaped Applicator
Energy Technology Data Exchange (ETDEWEB)
Park, J. [Seoul National University Hospital (Korea, Republic of)
2015-06-15
. These actions should be considered when they are consistent with the clinical task and patient anatomy. Learning Objectives: To become familiar with method of eye dose estimation for patient in specific situation of brain perfusion CT To become familiar with level of eye lens radiation doses in patients undergoing brain perfusion MDCT To understand methods for reducing eye lens dose to patient Jong Min Park, Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea Eye lens dosimetry in radiotherapy using contact lens-shaped applicator Dose calculation accuracy of commercial treatment planning systems is relatively low at shallow depths. Therefore, in-vivo measurements are often performed in the clinic to verify delivered doses to eye lens which are located at shallow depth. Current in-vivo dosimetry for eye lens during radiotherapy is generally performed with small in-vivo dosimeters on the surface of patient eyelid. Since this procedure potentially contains considerable uncertainty, a contact lens-shaped applicator made of acrylic (lens applicator) was developed for in-vivo measurements of eye lens dose during radiotherapy to reduce uncertainty. The lens applicator allows the insertion of commercially available metal oxide semiconductor field effect transistor (MOSFET) dosimeters. Computed tomography (CT) images of an anthropomorphic phantom with and without the lens applicator were acquired. A total of 20 VMAT plans were delivered to an anthropomorphic phantom and the doses with the lens applicator and the doses at the surface of the eyelid were measured using both micro and standard MOSFET dosimeters. The differences in measured dose at the surface of the eyelid from the calculated lens dose were acquired. The differences between the measured and the calculated doses at the lens applicator, as well as the differences between the measured and the calculated doses at the surface of the eyelid were acquired. The statistical significance of the
TU-E-201-01: Methods for Eye Lens Dosimetry and Studies On Lens Opacities with Interventionists
International Nuclear Information System (INIS)
Rehani, M.
2015-01-01
. These actions should be considered when they are consistent with the clinical task and patient anatomy. Learning Objectives: To become familiar with method of eye dose estimation for patient in specific situation of brain perfusion CT To become familiar with level of eye lens radiation doses in patients undergoing brain perfusion MDCT To understand methods for reducing eye lens dose to patient Jong Min Park, Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea Eye lens dosimetry in radiotherapy using contact lens-shaped applicator Dose calculation accuracy of commercial treatment planning systems is relatively low at shallow depths. Therefore, in-vivo measurements are often performed in the clinic to verify delivered doses to eye lens which are located at shallow depth. Current in-vivo dosimetry for eye lens during radiotherapy is generally performed with small in-vivo dosimeters on the surface of patient eyelid. Since this procedure potentially contains considerable uncertainty, a contact lens-shaped applicator made of acrylic (lens applicator) was developed for in-vivo measurements of eye lens dose during radiotherapy to reduce uncertainty. The lens applicator allows the insertion of commercially available metal oxide semiconductor field effect transistor (MOSFET) dosimeters. Computed tomography (CT) images of an anthropomorphic phantom with and without the lens applicator were acquired. A total of 20 VMAT plans were delivered to an anthropomorphic phantom and the doses with the lens applicator and the doses at the surface of the eyelid were measured using both micro and standard MOSFET dosimeters. The differences in measured dose at the surface of the eyelid from the calculated lens dose were acquired. The differences between the measured and the calculated doses at the lens applicator, as well as the differences between the measured and the calculated doses at the surface of the eyelid were acquired. The statistical significance of the
TU-E-201-03: Eye Lens Dosimetry in Radiotherapy Using Contact Lens-Shaped Applicator
International Nuclear Information System (INIS)
Park, J.
2015-01-01
. These actions should be considered when they are consistent with the clinical task and patient anatomy. Learning Objectives: To become familiar with method of eye dose estimation for patient in specific situation of brain perfusion CT To become familiar with level of eye lens radiation doses in patients undergoing brain perfusion MDCT To understand methods for reducing eye lens dose to patient Jong Min Park, Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea Eye lens dosimetry in radiotherapy using contact lens-shaped applicator Dose calculation accuracy of commercial treatment planning systems is relatively low at shallow depths. Therefore, in-vivo measurements are often performed in the clinic to verify delivered doses to eye lens which are located at shallow depth. Current in-vivo dosimetry for eye lens during radiotherapy is generally performed with small in-vivo dosimeters on the surface of patient eyelid. Since this procedure potentially contains considerable uncertainty, a contact lens-shaped applicator made of acrylic (lens applicator) was developed for in-vivo measurements of eye lens dose during radiotherapy to reduce uncertainty. The lens applicator allows the insertion of commercially available metal oxide semiconductor field effect transistor (MOSFET) dosimeters. Computed tomography (CT) images of an anthropomorphic phantom with and without the lens applicator were acquired. A total of 20 VMAT plans were delivered to an anthropomorphic phantom and the doses with the lens applicator and the doses at the surface of the eyelid were measured using both micro and standard MOSFET dosimeters. The differences in measured dose at the surface of the eyelid from the calculated lens dose were acquired. The differences between the measured and the calculated doses at the lens applicator, as well as the differences between the measured and the calculated doses at the surface of the eyelid were acquired. The statistical significance of the
LensEnt2: Maximum-entropy weak lens reconstruction
Marshall, P. J.; Hobson, M. P.; Gull, S. F.; Bridle, S. L.
2013-08-01
LensEnt2 is a maximum entropy reconstructor of weak lensing mass maps. The method takes each galaxy shape as an independent estimator of the reduced shear field and incorporates an intrinsic smoothness, determined by Bayesian methods, into the reconstruction. The uncertainties from both the intrinsic distribution of galaxy shapes and galaxy shape estimation are carried through to the final mass reconstruction, and the mass within arbitrarily shaped apertures are calculated with corresponding uncertainties. The input is a galaxy ellipticity catalog with each measured galaxy shape treated as a noisy tracer of the reduced shear field, which is inferred on a fine pixel grid assuming positivity, and smoothness on scales of w arcsec where w is an input parameter. The ICF width w can be chosen by computing the evidence for it.
Dating the time of birth: A radiocarbon calibration curve for human eye-lens crystallines
Energy Technology Data Exchange (ETDEWEB)
Kjeldsen, Henrik, E-mail: kjeldsen@phys.au.d [AMS 14C Dating Centre, Department of Physics and Astronomy, University of Aarhus, Aarhus (Denmark); Heinemeier, Jan [AMS 14C Dating Centre, Department of Physics and Astronomy, University of Aarhus, Aarhus (Denmark); Heegaard, Steffen [Eye Pathology Section, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen (Denmark); Jacobsen, Christina; Lynnerup, Niels [Department of Forensic Medicine, University of Copenhagen, Copenhagen (Denmark)
2010-04-15
Radiocarbon bomb-pulse dating has been used to measure the formation age of human eye-lens crystallines. Lens crystallines are special proteins in the eye-lens that consist of virtually inert tissue. The experimental data show that the radiocarbon ages to a large extent reflect the time of birth, in accordance with expectations. Moreover, it has been possible to develop an age model for the formation of the eye-lens crystallines. From this model a radiocarbon calibration curve for lens crystallines has been calculated. As a consequence, the time of birth of humans can be determined with an accuracy of a few years by radiocarbon dating.
Dating the time of birth: A radiocarbon calibration curve for human eye-lens crystallines
International Nuclear Information System (INIS)
Kjeldsen, Henrik; Heinemeier, Jan; Heegaard, Steffen; Jacobsen, Christina; Lynnerup, Niels
2010-01-01
Radiocarbon bomb-pulse dating has been used to measure the formation age of human eye-lens crystallines. Lens crystallines are special proteins in the eye-lens that consist of virtually inert tissue. The experimental data show that the radiocarbon ages to a large extent reflect the time of birth, in accordance with expectations. Moreover, it has been possible to develop an age model for the formation of the eye-lens crystallines. From this model a radiocarbon calibration curve for lens crystallines has been calculated. As a consequence, the time of birth of humans can be determined with an accuracy of a few years by radiocarbon dating.
Full Text Available ... prescription. There is no such thing as a "one size fits all" contact lens. Lenses that are not properly fitted may scratch the eye or cause blood vessels to grow into the cornea. Even if you have perfect vision, you need to get an eye exam and a prescription ...
... There is a risk of eye infection from bacteria in swimming pool water, hot tubs, lakes and the ocean Replace your contact lens storage case every 3 months or as directed by your eye care professional. Other Risks of Contact Lenses Other risks of contact lenses include pink eye ( ...
2001-01-01
Would the person who borrowed the large bubble chamber lens from the Microcosm workshops on the ISR please return it. This is a much used piece from our object archives. If anybody has any information about the whereabouts of this object, please contact Emma.Sanders@cern.ch Thank you
Thalos, Mariam
2013-01-01
Chemistry possesses a distinctive theoretical lens--a distinctive set of theoretical concerns regarding the dynamics and transformations of a perplexing variety of organic and nonorganic substances--to which it must be faithful. Even if it is true that chemical facts bear a special (reductive) relationship to physical facts, nonetheless it will…
Full Text Available ... wear any kind of contact lens. In Butler's case, the lenses caused an infection and left her with a corneal ... A recent article from U.S. News and World Report explains what ophthalmologists are and how they can ...
International Nuclear Information System (INIS)
Piskunov, V.A.
1981-01-01
The following connection of windings of electromagnet is suggested for simplification of the design of qUadrupole magnetic lens intended for use in radiotechnical and electron-optical devices. The mentioned windings are connected with each other by a bridge scheme and the variable resistors are switched in its diagonals in the lens containing four electromagnet with windings connected with two variable resistors the mobile contacts of which are connected with a direct current source. Current redistribution between left windings and right windings takes place at shift of mobile contact of variable resistor, and current redistribution between upper and low coils of electromagnets takes place at shifting mobile contact of the other variable resistor. In this case smooth and independent electron-optical misalignment of lens by two mutually perpendicular directions proceeds. Use of the given design of the lens in the oscillograph permits to use printing assembly for alignment plate and to reduce the number of connections at the expense of decreasing the number of resistors
Full Text Available ... can be purchased over-the-counter or on the Internet," says Thomas Steinemann, MD, professor of ophthalmology at ... ask for a prescription. There is no such thing as a "one size fits all" contact lens. Lenses that are not properly fitted may scratch the eye or cause blood vessels to grow into ...
Geometry-invariant GRIN lens: finite ray tracing.
Bahrami, Mehdi; Goncharov, Alexander V
2014-11-17
The refractive index distribution of the geometry-invariant gradient refractive index lens (GIGL) model is derived as a function of Cartesian coordinates. The adjustable external geometry of the GIGL model aims to mimic the shape of the human and animal crystalline lens. The refractive index distribution is based on an adjustable power-law profile, which provides additional flexibility of the model. An analytical method for layer-by-layer finite ray tracing through the GIGL model is developed and used to calculate aberrations of the GIGL model. The result of the finite ray tracing aberrations of the GIGL model are compared to those obtained with paraxial ray tracing. The derived analytical expression for the refractive index distribution can be employed in the reconstruction processes of the eye using the conventional ray tracing methods. The layer-by-layer finite ray tracing approach would be an asset in ray tracing through a modified GIGL model, where the refractive index distribution cannot be described analytically. Using the layer-by-layer finite ray-tracing method, the potential of the GIGL model in representing continuous as well as shell-like layered structures is illustrated and the results for both cases are presented and analysed.
International Nuclear Information System (INIS)
Hussein, M.S.; Bonin, H.W.; Lewis, B.J.
2014-01-01
The most recent versions of the Monte Carlo-based probabilistic transport code MCNP6 and the continuous energy reactor physics burnup calculation code Serpent allow for a 3-D geometry calculation accounting for the detailed geometry without unit-cell homogenization. These two codes are used to calculate the axial and radial flux and power distributions for a CANDU6 GENTILLY-2 nuclear reactor core with 37-element fuel bundles. The multiplication factor, actual flux distribution and power density distribution were calculated by using a tally combination for MCNP6 and detector analysis for Serpent. Excellent agreement was found in the calculated flux and power distribution. The Serpent code is most efficient in terms of the computational time. (author)
Energy Technology Data Exchange (ETDEWEB)
Hussein, M.S.; Bonin, H.W., E-mail: mohamed.hussein@rmc.ca, E-mail: bonin-h@rmc.ca [Royal Military College of Canada, Dept. of Chemistry and Chemical Engineering, Kingston, ON (Canada); Lewis, B.J., E-mail: Brent.Lewis@uoit.ca [Univ. of Ontario Inst. of Tech., Faculty of Energy Systems and Nuclear Science, Oshawa, ON (Canada)
2014-07-01
The most recent versions of the Monte Carlo-based probabilistic transport code MCNP6 and the continuous energy reactor physics burnup calculation code Serpent allow for a 3-D geometry calculation accounting for the detailed geometry without unit-cell homogenization. These two codes are used to calculate the axial and radial flux and power distributions for a CANDU6 GENTILLY-2 nuclear reactor core with 37-element fuel bundles. The multiplication factor, actual flux distribution and power density distribution were calculated by using a tally combination for MCNP6 and detector analysis for Serpent. Excellent agreement was found in the calculated flux and power distribution. The Serpent code is most efficient in terms of the computational time. (author)
International Nuclear Information System (INIS)
Doron, E.; Ohaion, H.; Asculai, E.
1985-05-01
A software package intended for the assessments of risks resulting from accidental release of radioactive materials from a nuclear power plant is presented. The models and the various programs based on them, are described. The work includes detailed operating instructions for the various programs, as well as instructions for the preparation of the necessary input data. Various options are described for additions and changes to the programs with the aim of extending their usefulness to more general cases from the aspects of meteorology and pollution sources. finally, a sample calculation that enables the user to test the proper functioning of the whole package, as well as his own proficiency in its use, is given. (author)
Energy Technology Data Exchange (ETDEWEB)
Maennel, W. [Friedrich-Alexander-Univ., Erlangen-Nuernberg (Germany). Betriebswirtschafliches Inst.
2004-04-01
Utilities insist that contrary to the opinions of the Federal Cartel Office and network users, distribution network operation is a high-risk enterprise. The contribution starts by listing typical relevant risks in power distribution and then proceeds to discussing risk factors one by one. Empirical findings generated with the Capital Asset Pricing Mode (CAPM) prove that the conservative approach for calculating the risk-based surcharges laid down in the VV II plus agreement is appropriate. (orig./CB) [German] Entgegen der Auffassung von Bundeskartellbehoerden und Netznutzern ist das stark anlagenintensive Netzgeschaeft mit bedeutsamen Unternehmerrisiken behaftet, deren Ueberwaelzung nur begrenzt moeglich ist. Ausgehend von generell bedeutsamen und typischen Unternehmerrisiken im Stromverteilungssektor beschaeftigt sich der Artikel mit den direkt auf die Eigenkapitalverzinsung einwirkenden Risikofaktoren. Mit dem Capital Asset Pricing Mode (CAPM) genierierte empirische Befunde bestaetigen die konservativen Wagniszuschlaege in der VV II plus. (orig.)
Note on the power divergence in lattice calculations of ΔI=1/2 K→ππ amplitudes at MK=Mπ
International Nuclear Information System (INIS)
Golterman, Maarten; Lin, C.-J. David; Pallante, Elisabetta
2004-01-01
In this Brief Report, we clarify a point concerning the power divergence in lattice calculations of ΔI=1/2 K→ππ decay amplitudes. There have been worries that this divergence might show up in the Minkowski amplitudes at M K =M π with all the mesons at rest. Here we demonstrate, via an explicit calculation in leading-order chiral perturbation theory, that the power divergence is absent at the above kinematic point, as predicted by CPS symmetry
Lessons learned: wrong intraocular lens.
Schein, Oliver D; Banta, James T; Chen, Teresa C; Pritzker, Scott; Schachat, Andrew P
2012-10-01
To report cases involving the placement of the wrong intraocular lens (IOL) at the time of cataract surgery where human error occurred. Retrospective small case series, convenience sample. Seven surgical cases. Institutional review of errors committed and subsequent improvements to clinical protocols. Lessons learned and changes in procedures adapted. The pathways to a wrong IOL are many but largely reflect some combination of poor surgical team communication, transcription error, lack of preoperative clarity in surgical planning or failure to match the patient, and IOL calculation sheet with 2 unique identifiers. Safety in surgery involving IOLs is enhanced both by strict procedures, such as an IOL-specific "time-out," and the fostering of a surgical team culture in which all members are encouraged to voice questions and concerns. Copyright © 2012 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Verduzco, Laura E.; Duffey, Michael R.; Deason, Jonathan P.
2007-01-01
At this time, hydrogen-based power plants and large hydrogen production facilities are capital intensive and unable to compete financially against hydrocarbon-based energy production facilities. An option to overcome this problem and foster the introduction of hydrogen technology is to introduce small and medium-scale applications such as residential and community hydrogen refueling units. Such units could potentially be used to generate both electricity and heat for the home, as well as hydrogen fuel for the automobile. Cost modeling for the integration of these three forms of energy presents several methodological challenges. This is particularly true since the technology is still in the development phase and both the financial and the environmental cost must be calculated using mainly secondary sources. In order to address these issues and aid in the design of small and medium-scale hydrogen systems, this study presents a computer model to calculate financial and environmental costs of this technology using different hydrogen pathways. The model can design and compare hydrogen refueling units against hydrocarbon-based technologies, including the 'gap' between financial and economic costs. Using the methodology, various penalties and incentives that can foster the introduction of hydrogen-based technologies can be added to the analysis to study their impact on financial cost
International Nuclear Information System (INIS)
Crabol, B.; Romeo, E.; Nester, K.
1992-01-01
In case of an accident in a nuclear power plant near the French-German border different schemes for dispersion calculations in both countries will currently be applied. An intercomparison of these schemes initiated from the German-French Commission for the safety of nuclear installations (DFK) revealed in some meteorological situations large differences in the resulting concentrations for radionuclides. An ad hoc working group was installed by the DFK with the mandate to analyse the reasons for the different model results and also to consider new theoretical concepts. The working group has agreed to apply a Gaussian puff model for emergency response calculations. The results of the model based on turbulence parameterization via similarity approach or spectral theory - have been compared with tracer experiments for different emission heights and atmospheric stability regimes. As a reference the old modelling approaches have been included in the study. The simulations with the similarity approach and the spectral theory show a slightly better agreement to the measured concentration data than the schemes used in the past. Instead of diffusion categories both new approaches allow a continuous characterization of the atmospheric dispersion conditions. Because the spectral approach incorporates the sampling time of the meteorological data as an adjustable parameter thereby offering the possibility to adjust the dispersion model to different emission scenarios this turbulence parameterization scheme will be foreseen as the basis for a joint French-German puff model
New trends in intraocular lens imaging
Millán, María S.; Alba-Bueno, Francisco; Vega, Fidel
2011-08-01
As a result of modern technological advances, cataract surgery can be seen as not only a rehabilitative operation, but a customized procedure to compensate for important sources of image degradation in the visual system of a patient, such as defocus and some aberrations. With the development of new materials, instruments and surgical techniques in ophthalmology, great progress has been achieved in the imaging capability of a pseudophakic eye implanted with an intraocular lens (IOL). From the very beginning, optical design has played an essential role in this progress. New IOL designs need, on the one hand, theoretical eye models able to predict optical imaging performance and on the other hand, testing methods, verification through in vitro and in vivo measurements, and clinical validation. The implant of an IOL requires a precise biometry of the eye, a prior calculation from physiological data, and an accurate position inside the eye. Otherwise, the effects of IOL calculation errors or misplacements degrade the image very quickly. The incorporation of wavefront aberrometry into clinical ophthalmology practice has motivated new designs of IOLs to compensate for high order aberrations in some extent. Thus, for instance, IOLs with an aspheric design have the potential to improve optical performance and contrast sensitivity by reducing the positive spherical aberration of human cornea. Monofocal IOLs cause a complete loss of accommodation that requires further correction for either distance or near vision. Multifocal IOLs address this limitation using the principle of simultaneous vision. Some multifocal IOLs include a diffractive zone that covers the aperture in part or totally. Reduced image contrast and undesired visual phenomena, such as halos and glare, have been associated to the performance of multifocal IOLs. Based on a different principle, accommodating IOLs rely on the effort of the ciliary body to increase the effective power of the optical system of the
Directory of Open Access Journals (Sweden)
N. J. Milardovich
2014-10-01
Full Text Available A numerical investigation on the harmonic disturbances in low-voltage cables feeding large LED loads is reported. A frequency domain analysis on several commercially-available LEDs was performed to investigate the signature of the harmonic current injected into the power system. Four-core cables and four single-core cable arrangements (three phases and neutral of small, medium, and large conductor cross sections, with the neutral conductor cross section approximately equal to the half of the phase conductors, were examined. The cables were modelled by using electromagnetic finite-element analysis software. High harmonic power losses (up to 2.5 times the value corresponding to an undistorted current of the same rms value of the first harmonic of the LED current were found. A generalized ampacity model was employed for re-rating the cables. It was found that the cross section of the neutral conductor plays an important role in the derating of the cable ampacity due to the presence of a high-level of triplen harmonics in the distorted current. The ampacity of the cables should be derated by about 40 %, almost independent of the conductor cross sections. The calculation have shown that an incoming widespread use of LED lamps in lighting could create significant additional harmonic losses in the supplying low-voltage lines, and thus more severely harmonic emission limits should be defined for LED lamps.
A Model of the Effect of Lens Development on Refraction in Schoolchildren.
He, Ji C
2017-12-01
The study provides a new theory on the mechanism underlying myopia development, and it could be useful in clinical practice to control myopia development in schoolchildren. To model the effect of the crystalline lens on refractive development in schoolchildren. The Zemax 13 was used to calculate Zernike aberrations and refractions across 50° horizontal visual fields. Optical effects of the anterior chamber depth, lens thickness, and radii of curvature of the lens surfaces on refractions were modeled. Refractive changes induced by lens development in emmetropic and myopic eyes, based on a previous longitudinal study from literature, were calculated. A lens thickness reduction with an anterior chamber depth deepening caused a hyperopic shift over the visual fields and even more at the periphery. Opposite effects were found when the lens was thinned without any change of the anterior chamber depth. While a flattening of the anterior lens surface produced hyperopic refractions overall, a posterior lens flattening caused a myopic shift at the periphery, but a hyperopic shift of the central refraction. In the myopic eye, lens development induced refractive change toward more hyperopic over the visual fields and more at the periphery. Lens thinning and lens axial movement participate in peripheral refractive development in schoolchildren, and lens development with a deeper anterior chamber depth and a flatter lens surface in the myopic eye could generate extra hyperopia over visual fields. The myopic lens development could be due to a backward movement of the lens, driven by a backward growth of the ciliary process, which might be a causative factor of myopia development.
Model calculations of the chemical processes occurring in the plume of a coal-fired power plant
Energy Technology Data Exchange (ETDEWEB)
Meagher, J F; Luria, M
1982-02-01
Computer simulations of the homogeneous, gas phase chemical reactions which occur in the plume of a coal-fired power plant were conducted in an effort to understand the influence of various environmental parameters on the production of secondary pollutants. Input data for the model were selected to reproduce the dilution of a plume from a medium-sized power plant. The environmental conditions chosen were characteristic of those found during mid-August in the south-eastern United States. Under most conditions examined, it was found that hydroxyl radicals were the most important species in the homogeneous conversion of stack gases into secondary pollutants. Other free radicals, such as HO/sub 2/ and CH/sub 3/O/sub 2/, exceeded the contribution of HO radicals only when high background hydrocarbon concentrations are used. The conversion rates calculated for the oxidation of SO/sub 2/ to SO/sub 4//sup 2 -/ in these plumes were consistent with those determined experimentally. The concentrations and relative proportions of NO/sub x/ (from the power plant) and reactive hydrocarbons (from the background air) determine, to a large extent, the plume reactivity. Free radical production is suppressed during the initial stages of dilution due to the high NO/sub x/ levels. Significant dilution is required before a suitable mix is attained which can sustain the free radical chain processes common to smog chemistry. In most cases, the free radical concentrations were found to pass through maxima and return to background levels. Under typical summertime conditions, the hyroxyl radical concentration was found to reach a maximum at a HC/NO/sub x/ ratio of approximately 20.
Electronic states in a quantum lens
International Nuclear Information System (INIS)
Rodriguez, Arezky H.; Trallero-Giner, C.; Ulloa, S. E.; Marin-Antuna, J.
2001-01-01
We present a model to find analytically the electronic states in self-assembled quantum dots with a truncated spherical cap (''lens'') geometry. A conformal analytical image is designed to map the quantum dot boundary into a dot with semispherical shape. The Hamiltonian for a carrier confined in the quantum lens is correspondingly mapped into an equivalent operator and its eigenvalues and eigenfunctions for the corresponding Dirichlet problem are analyzed. A modified Rayleigh-Schro''dinger perturbation theory is presented to obtain analytical expressions for the energy levels and wave functions as a function of the spherical cap height b and radius a of the circular cross section. Calculations for a hard wall confinement potential are presented, and the effect of decreasing symmetry on the energy values and eigenfunctions of the lens-shape quantum dot is studied. As the degeneracies of a semicircular geometry are broken for b≠a, our perturbation approach allows tracking of the split states. Energy states and electronic wave functions with m=0 present the most pronounced influence on the reduction of the lens height. The method and expressions presented here can be straightforwardly extended to deal with more general Hamiltonians, including strains and valence-band coupling effects in Group III--V and Group II--VI self-assembled quantum dots
Compound refractive X-ray lens
International Nuclear Information System (INIS)
Nygren, D.R.; Cahn, R.; Cederstrom, B.; Danielsson, M.; Vestlund, J.
2000-01-01
An apparatus and method are disclosed for focusing X-rays. In one embodiment, his invention is a commercial-grade compound refractive X-ray lens. The commercial-grade compound refractive X-ray lens includes a volume of low-Z material. The volume of low-Z material has a first surface which is adapted to receive X-rays of commercially-applicable power emitted from a commercial-grade X-ray source. The volume of low-Z material also has a second surface from which emerge the X-rays of commercially-applicable power which were received at the first surface. Additionally, the commercial-grade compound refractive X-ray lens includes a plurality of openings which are disposed between the first surface and the second surface. The plurality of openings are oriented such that the X-rays of commercially-applicable power which are received at the first surface, pass through the volume of low-Z material and through the plurality openings. In so doing, the X-rays which emerge from the second surface are refracted to a focal point
Compound refractive X-ray lens
Nygren, David R.; Cahn, Robert; Cederstrom, Bjorn; Danielsson, Mats; Vestlund, Jonas
2000-01-01
An apparatus and method for focusing X-rays. In one embodiment, his invention is a commercial-grade compound refractive X-ray lens. The commercial-grade compound refractive X-ray lens includes a volume of low-Z material. The volume of low-Z material has a first surface which is adapted to receive X-rays of commercially-applicable power emitted from a commercial-grade X-ray source. The volume of low-Z material also has a second surface from which emerge the X-rays of commercially-applicable power which were received at the first surface. Additionally, the commercial-grade compound refractive X-ray lens includes a plurality of openings which are disposed between the first surface and the second surface. The plurality of openings are oriented such that the X-rays of commercially-applicable power which are received at the first surface, pass through the volume of low-Z material and through the plurality openings. In so doing, the X-rays which emerge from the second surface are refracted to a focal point.
Energy Technology Data Exchange (ETDEWEB)
Martin, J [Commissariat a l' Energie Atomique, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)
1966-10-01
The apparatus studied is a digital calculating assembly which makes it possible to prepare and to present numerically the period and power of a nuclear reactor during operation, from start-up to nominal power. The pulses from a fission chamber are analyzed continuously, using real time. A small number of elements is required because of the systematic use of a calculation technique comprising the determination of a base 2 logarithm by a linear approximation. The accuracy obtained for the period is of the order of 14%; the response time of the order of the calculated period value. An approximate value of the power (30%) is given at each calculation cycle together with the power thresholds required for the control. (author) [French] L'appareil etudie est un ensemble de calcul digital permettant d'elaborer et d'afficher numeriquement la periode et la puissance, d'un reacteur nucleaire lors de son fonctionnement depuis le demarrage jusqu'a la puissance nominale. Il traite en temps reel, de facon continue, les impulsions en provenance d'une chambre de fission. Grace a l'utilisation systematique d'une technique de calcul, la determination d'un logarithme a base 2 par approximation lineaire, un nombre reduit d'elements est utilise. La precision obtenue sur la periode est de l'ordre de 14 pour cent, le temps de reponse de l'ordre de la valeur de la periode calculee. Un ordre de grandeur de la puissance (30 pour cent) est donne a chaque cycle de calcul ainsi que des seuils de puissance necessaires au controle. (auteur)
International Nuclear Information System (INIS)
Silva, M
2006-01-01
The Atucha I Nuclear Power Plant (CNA-I) has enough room to store its spent fuel (SF) in damp in its two pool houses until the middle of 2015.Before that date there is the need to have an interim dry storage system for spent fuel that would make possible to empty at least one of the pools, whether to keep the plant operating if its useful life is extended, or to be able to empty the reactor core in case of decommissioning.Nucleolectrica Argentina S.A. (NA-SA) and the Comision Nacional de Energia Atomica (CNEA), due to their joint responsibility in the management of the SF, have proposed interim dry storage systems.These systems have to be evaluated in order to choose one of them by the end of 2006.In this work the Monte Carlo code MCNP was used to make the criticality and shielding calculations corresponding to the model proposed by CNEA.This model suggests the store of sealed containers with 36 or 37 SF in concrete modules.Each one of the containers is filled in the pool houses and transported to the module in a transference cask with lead walls.The results of the criticality calculations indicates that the solutions of SF proposed have widely fulfilled the requirements of subcriticality, even in supposed extreme accidental situations.Regarding the transference cask, the SF dose rate estimations allow us to make a feedback for the design aiming to the geometry and shielding improvements.Regarding the store modules, thicknesses ranges of concrete walls are suggested in order to fulfill the dose requirements stated by the Autoridad Regulatoria Nuclear Argentina [es
FARSAKOĞLU, Ö. Faruk
2014-01-01
The effect of Coddington factors on aberration functions has been analysed using thin lens approximation. Minimizing spherical aberrations of singlet lenses using Coddington factors in lens design depending on lens manufacturing is discussed. Notation of lens test plate pairs used in lens manufacturing is also presented in terms of Coddington shape factors.
Focusing properties of a square electrostatic rainbow lens
International Nuclear Information System (INIS)
Telečki, I.; Petrović, S.; Beličev, P.; Rađenović, B.; Balvanović, R.; Bojović, B.; Nešković, N.
2012-01-01
This paper is devoted to the focusing properties of a square electrostatic rainbow lens, which is a novel ion beam optical element. We consider the transmission of parallel and non-parallel proton beams of the initial kinetic energy of 10 keV through this lens. The potential of the electrodes of the lens is chosen to be 2 kV. The electrostatic potential and components of the electric field in the region of the lens are calculated using a three-dimensional finite element computer code. We investigate the spatial and angular distributions of protons propagating through the lens and in the drift space after it. It is confirmed that the evolutions of these distributions are determined by the evolutions of the corresponding rainbow lines, generated using the theory of crystal rainbows. The beam is separated into two components. One beam component, appearing as a beam core, is generated dominantly by the focused protons. Its boundary line in the transverse position plane can be very well approximated by a hypotrochoid. The other beam component is generated dominantly by the defocused protons. We present the focusing coefficient of the lens, the confining coefficients of the lens for the focused and defocused protons, the density of the beam core, the vertical or horizontal emittance of the beam core, and the brightness of the beam core.
LASL lens design procedure: simple, fast, precise, versatile
International Nuclear Information System (INIS)
Brixner, B.
1978-11-01
The Los Alamos Scientific Laboratory general-purpose lens design procedure optimizes specific lens prescriptions to obtain the smallest possible image spots and therefore near-spherical wave fronts of light converging on all images in the field of view. Optical image errors are analyzed in much the same way that they are measured on the optical bench. This lens design method is made possible by using the full capabilities of large electronic computers. First, the performance of the whole lens is sampled with many precisely traced skew rays. Next, lens performance is analyzed with spot diagrams generated by the many rays. Third, lens performance is optimized with a least squares system aimed at reducing all image errors to zero. This statistical approach to lens design uses skew rays and precisely measured ray deviations from ideal image points to achieve greater accuracy than was possible with the classical procedure, which is based on approximate expressions derived from simplified ray traces developed for pencil-and-paper calculations
Calculation of the quadrupole-lense fringing field
International Nuclear Information System (INIS)
Arzumanov, A.A.
1978-01-01
With the aim of decreasing the scattering field effect at electrode edge or quadrupole lens poles with conformal transformations the scattering fields of electric quadrupole lens, two-electrode lens with the electrodes in a hyperbola form, as well as magnetic lens with hyperbolic poles are calculated. For the two-electrode system with kappa=0.1 (kappa - is coefficient, characterizing the rate of field intensity change in the lens) field distortion equals 1.8%. The comparison of experimental data with the calculation data has shown that with a rather high accuracy the scattering field effect in electric and magnetic lenses with hyperbolic poles may be taken into account
Crystalline lens thickness determines the perceived chromatic difference in magnification.
Chen, Yun; Schaeffel, Frank
2014-03-01
Since the origin of the high interindividual variability of the chromatic difference in retinal image magnification (CDM) in the human eye is not well understood, optical parameters that might determine its magnitude were studied in 21 healthy subjects with ages ranging from 21 to 58 years. Two psychophysical procedures were used to quantify CDM. They produced highly correlated results. First, a red and a blue square, presented on a black screen, had to be matched in size by the subjects with their right eyes. Second, a filled red and blue square, flickering on top of each other at 2 Hz, had to be adjusted in perceived brightness and then in size to minimize the impression of flicker. CDM varied widely among subjects from 0.0% to 3.6%. Biometric ocular parameters were measured with low coherence interferometry and crystalline lens tilt and decentration with a custom-built Purkinjemeter. Correlations were studied between CDM and corneal power, anterior chamber depth, lens thickness, lens tilt and lens decentration, and vitreous chamber depths. Lens thickness was found significantly correlated with CDM and accounted for 64% of its variance. Vertical lens tilt and decentration were also significantly correlated. It was also found that CDM increased by 3.5% per year, and part of this change can be attributed to the age-related increase in lens thickness.
Preliminary Investigation of an Active PLZT Lens
Lightsey, W. D.; Peters, B. R.; Reardon, P. J.; Wong, J. K.
2001-01-01
The design, analysis and preliminary testing of a prototype Adjustable Focus Optical Correction Lens (AFOCL) is described. The AFOCL is an active optical component composed of solid state lead lanthanum-modified zirconate titanate (PLZT) ferroelectric ceramic with patterned indium tin oxide (ITO) transparent surface electrodes that modulate the refractive index of the PLZT to function as an electro-optic lens. The AFOCL was developed to perform optical re-alignment and wavefront correction to enhance the performance of Ultra-Lightweight Structures and Space Observatories (ULSSO). The AFOCL has potential application as an active optical component within a larger optical system. As such, information from a wavefront sensor would be processed to provide input to the AFOCL to drive the sensed wavefront to the desired shape and location. While offering variable and rapid focussing capability (controlled wavefront manipulation) similar to liquid crystal based spatial light modulators (SLM), the AFOCL offers some potential advantages because it is a solid-state, stationary, low-mass, rugged, and thin optical element that can produce wavefront quality comparable to the solid refractive lens it replaces. The AFOCL acts as a positive or negative lens by producing a parabolic phase-shift in the PLZT material through the application of a controlled voltage potential across the ITO electrodes. To demonstrate the technology, a 4 mm diameter lens was fabricated to produce 5-waves of optical power operating at 2.051 micrometer wavelength. Optical metrology was performed on the device to measure focal length, optical quality, and efficiency for a variety of test configurations. The data was analyzed and compared to theoretical data available from computer-based models of the AFOCL.
Energy Technology Data Exchange (ETDEWEB)
Goluoglu, S.
2001-01-11
Transportation of low-enriched uranium (LEU) and mixed-oxide (MOX) assemblies to and within the VVER-1000-type Balakovo Nuclear Power Plant is investigated. Effective multiplication factors for fresh fuel assemblies on the railroad platform, fresh fuel assemblies in the fuel transportation vehicle, and fresh fuel assemblies in the spent fuel storage pool are calculated. If there is no absorber between the units, the configurations with all MOX assemblies result in higher effective multiplication factors than the configurations with all LEU assemblies when the system is dry. When the system is flooded, the configurations with all LEU assemblies result in higher effective multiplication factors. For normal operating conditions, effective multiplication factors for all configurations are below the presumed upper subcritical limit of 0.95. For an accident condition of a fully loaded fuel transportation vehicle that is flooded with low-density water (possibly from a fire suppression system), the presumed upper subcritical limit is exceeded by configurations containing LEU assemblies.
Energy Technology Data Exchange (ETDEWEB)
Osmani, O; Duvenbeck, A; Akcoeltekin, E; Meyer, R; Schleberger, M [Department of Physics, University of Duisburg-Essen, D-47048 Duisburg (Germany); Lebius, H [CIMAP, blvd Henri Becquerel, 14070 Caen (France)], E-mail: marika.schleberger@uni-due.de
2008-08-06
In recent experiments the irradiation of insulators of perovskite type with swift (E{approx}100 MeV) heavy ions under glancing incidence has been shown to provide a unique means to generate periodically arranged nanodots at the surface. The physical origin of these patterns has been suggested as stemming from a highly anisotropic electron density distribution within the bulk. In order to show the relevance of the electron density distribution of the target we present a model calculation for the system Xe{sup 23+} {yields} SrTiO{sub 3} that is known to produce the aforementioned surface modifications. On the basis of the Lindhard model of electronic stopping, we employ highly-resolved ab initio electron density data to describe the conversion of kinetic energy into excitation energy along the ion track. The primary particle dynamics are obtained via integration of the Newtonian equations of motion that are governed by a space- and time-dependent frictional force originating from Lindhard stopping. The analysis of the local electronic stopping power along the ion track reveals a pronounced periodic structure. The periodicity length varies strongly with the particular choice of the polar angle of incidence and is directly correlated to the experimentally observed formation of periodic nanodots at insulator surfaces.
Two families of astrophysical diverging lens models
Er, Xinzhong; Rogers, Adam
2018-03-01
In the standard gravitational lensing scenario, rays from a background source are bent in the direction of a foreground lensing mass distribution. Diverging lens behaviour produces deflections in the opposite sense to gravitational lensing, and is also of astrophysical interest. In fact, diverging lensing due to compact distributions of plasma has been proposed as an explanation for the extreme scattering events that produce frequency-dependent dimming of extragalactic radio sources, and may also be related to the refractive radio wave phenomena observed to affect the flux density of pulsars. In this work we study the behaviour of two families of astrophysical diverging lenses in the geometric optics limit, the power law, and the exponential plasma lenses. Generally, the members of these model families show distinct behaviour in terms of image formation and magnification, however the inclusion of a finite core for certain power-law lenses can produce a caustic and critical curve morphology that is similar to the well-studied Gaussian plasma lens. Both model families can produce dual radial critical curves, a novel distinction from the tangential distortion usually produced by gravitational (converging) lenses. The deflection angle and magnification of a plasma lens vary with the observational frequency, producing wavelength-dependent magnifications that alter the amplitudes and the shape of the light curves. Thus, multiwavelength observations can be used to physically constrain the distribution of the electron density in such lenses.
International Nuclear Information System (INIS)
Sublet, J.
1998-01-01
The calculation of activation inventories is a key input to virtually all aspects of the safety and environmental assessment of fusion power devices, such as ITER. For the licensing of such devices, regulatory authorities will require proof that the calculations of activation, and calculations to which activation quantities are inputs, are either correct or conservative. An important aspect of activation is decay heat power. In fusion power plants, decay power arises after shutdown from the energy released in the decay of the products of neutron activation, mainly from gamma and beta rays. Computation of the decay power is performed by sophisticated computer codes which solve the large number of coupled differential equations which govern the generation and decay chains for the many nuclides involved. They rely on a large volume of nuclear data, both neutron activation cross-sections and radioactive decay data. Validation of decay power code predictions by means of direct comparison with integral data measurements of sample structural materials under fusion-typical neutron spectra generates confidence in the decay power values calculated. It also permits an assessment of the adequacy of the methods and nuclear data and indicates any inaccuracy or omission that may have led to erroneous results. No experimental data on decay power existed for fusion reactor structural materials and irradiation conditions before a series of experiments were performed using the Fusion Neutron Source FNS facility at the Japan Atomic Energy Research Institute JAERI. Fusion relevant material samples were irradiated in a simulated D-T neutron field for times up to 7 hours and the decay power so generated measured for cooling times up to three months. Using the highly sensitive Whole Energy Absorption Spectrometer (WEAS) method, both β and γ rays decay energies were measured at selected cooling times as early as one minute after the irradiation ended. Coupled to the experiments, and at
Directory of Open Access Journals (Sweden)
Pavlović Mirjana
2015-01-01
Full Text Available In this paper we deal with ethnically diverse categories of residents of the Duchy and the Kingdom of Serbia in national censuses conducted between 1834 and 1910, with an accent on those conducted from 1862 - the period when official state statistics institutions were established. We do not deal foremost with numbers and statistical analyses, but with censuses as such - as we consider censuses to be an important instrument in the hands of the state which has the power to count, delineate and categorize the population. In this paper we give special attention to the relationship between the census officials and (ethnic minorities: when and in what measure the interest in counting and documenting “others” emerges in Serbia, how they are categorized, which terms are used for minorities as such or various groups specifically, and how the data on these is interpreted. From this a certain image emerges - an image of the relationship between the state and ethnic “others”. This research displays a prominent tendency in this historical period to view minorities not as an integral part of the state and society, but as an alien, foreign body in it. Also, the meaning of the existence of ethnically diverse groups is often minimized, due to their alleged small numbers. Even though valid conclusions on the position of minorities in the state and society would require more thorough research and more sources, we consider the way in which ethnically diverse groups of citizens were treated in state censuses as very indicative in this sense.
International Nuclear Information System (INIS)
Sion, N.
2016-01-01
Protecting the human body from the effects of ionizing radiation is essential to forestall stochastic effects and require placing limits on the effective dose. Dose limits on specific organs are also necessary to reduce the deterministic effects and tissue reactions. The standard for radiation protection was ISO 15382 (2002) which mainly dealt with beta radiation for nuclear power plant workers. Clearly an update is required to allow for new technology and the proliferative use of radiation in medical practices. There is a need for more explicit radiation monitoring to operators and staff. ICRP118 (International Commission on Radiological Protection), Ref. 1, evolved their recommendations to include eye lens doses as a follow on to their publication 103 and to focus on radiation exposures. It provides updated estimates of 'practical' threshold doses for tissue injury at the level of 1% incidence. This paper discusses the current status and the recommendation for a drastic reduction of the dose limit to the eye lens. (author)
Simulation of light propagation in the thin-film waveguide lens
Malykh, M. D.; Divakov, D. V.; Sevastianov, L. A.; Sevastianov, A. L.
2018-04-01
In this paper we investigate the solution of the problem of modeling the propagation of electromagnetic radiation in three-dimensional integrated optical structures, such as waveguide lenses. When propagating through three-dimensional waveguide structures the waveguide modes can be hybridized, so the mathematical model of their propagation must take into account the connection of TE- and TM-mode components. Therefore, an adequate consideration of hybridization of the waveguide modes is possible only in vector formulation of the problem. An example of three-dimensional structure that hybridizes waveguide modes is the Luneburg waveguide lens, which also has focusing properties. If the waveguide lens has a radius of the order of several tens of wavelengths, its variable thickness at distances of the order of several wavelengths is almost constant. Assuming in this case that the electromagnetic field also varies slowly in the direction perpendicular to the direction of propagation, one can introduce a small parameter characterizing this slow varying and decompose the solution in powers of the small parameter. In this approach, in the zeroth approximation, scalar diffraction problems are obtained, the solution of which is less resource-consuming than the solution of vector problems. The calculated first-order corrections of smallness describe the connection of TE- and TM-modes, so the solutions obtained are weakly-hybridized modes. The formulation of problems and methods for their numerical solution in this paper are based on the authors' research on waveguide diffraction on a lens in a scalar formulation.
International Nuclear Information System (INIS)
Kim, J. O.; Kim, J. K.
1997-01-01
Relative power density distributions of the Kori unit 1 pressurized water reactor calculated by Monte Carlo modeling with the MCNP code. The Kori unit 1 core is modeled on a three-dimensional representation of the one-eighth of the reactor in-vessel component with reflective boundaries at 0 and 45 degrees. The axial core model is based on half core symmetry and is divided into four axial segments. Fission reaction density in each rod is calculated by following 100 cycles with 5,000 test neutrons in each cycle after starting with a localized neutron source and ten noncontributing settle cycles. Relative assembly power distributions are calculated from fission reaction densities of rods in assembly. After 100 cycle calculations, the system coverages to a κ value of 1.00039 ≥ 0.00084. Relative assembly power distribution is nearly the same with that of the Kori unit 1 FSAR. Applicability of the full-scope Monte Carlo simulation in the power distribution calculation is examined by the relative root mean square error of 2.159%. (author)
International Nuclear Information System (INIS)
Guimaraes, A.C.F.; Goes, A.G.
1988-12-01
The ''RASO'', an activity and operational situation report for Angra 1, is transmitted daily by phone to CNEN by inspectors living at Angra 1 site, anal shows the parameters about the operational status of the nuclear power plant. In the period of 26.10.88 to 04.12.88 a discretized power serie was determined for greater time intervals than the original serie, and then new concentrations were calculated using origem 2 computer code. (author) [pt
International Nuclear Information System (INIS)
Stepanov, V.I.; Koryagin, A.V.; Ruzankov, V.N.
1988-01-01
Computer-aided design system for a complex of problems concerning calculation and analysis of engineering and economical indices of NPP power units is described. In the system there are means for automated preparation and debugging of data base software complex, which realizes th plotted algorithm in the power unit control system. Besides, in the system there are devices for automated preparation and registration of technical documentation
Characteristics of the thick, compound refractive lens
International Nuclear Information System (INIS)
Pantell, Richard H.; Feinstein, Joseph; Beguiristain, H. Raul; Piestrup, Melvin A.; Gary, Charles K.; Cremer, Jay T.
2003-01-01
A compound refractive lens (CRL), consisting of a series of N closely spaced lens elements each of which contributes a small fraction of the total focusing, can be used to focus x rays or neutrons. The thickness of a CRL can be comparable to its focal length, whereupon a thick-lens analysis must be performed. In contrast with the conventional optical lens, where the ray inside the lens follows a straight line, the ray inside the CRL is continually changing direction because of the multiple refracting surfaces. Thus the matrix representation for the thick CRL is quite different from that for the thick optical lens. Principal planes can be defined such that the thick-lens matrix can be converted to that of a thin lens. For a thick lens the focal length is greater than for a thin lens with the same lens curvature, but this lengthening effect is less for the CRL than for the conventional optical lens
Heo, Seo Weon; Kim, Hyungsuk
2010-05-01
An estimation of ultrasound attenuation in soft tissues is critical in the quantitative ultrasound analysis since it is not only related to the estimations of other ultrasound parameters, such as speed of sound, integrated scatterers, or scatterer size, but also provides pathological information of the scanned tissue. However, estimation performances of ultrasound attenuation are intimately tied to the accurate extraction of spectral information from the backscattered radiofrequency (RF) signals. In this paper, we propose two novel techniques for calculating a block power spectrum from the backscattered ultrasound signals. These are based on the phase-compensation of each RF segment using the normalized cross-correlation to minimize estimation errors due to phase variations, and the weighted averaging technique to maximize the signal-to-noise ratio (SNR). The simulation results with uniform numerical phantoms demonstrate that the proposed method estimates local attenuation coefficients within 1.57% of the actual values while the conventional methods estimate those within 2.96%. The proposed method is especially effective when we deal with the signal reflected from the deeper depth where the SNR level is lower or when the gated window contains a small number of signal samples. Experimental results, performed at 5MHz, were obtained with a one-dimensional 128 elements array, using the tissue-mimicking phantoms also show that the proposed method provides better estimation results (within 3.04% of the actual value) with smaller estimation variances compared to the conventional methods (within 5.93%) for all cases considered. Copyright 2009 Elsevier B.V. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Carvalho, Monaco [PETROBRAS, Rio de Janeiro, RJ (Brazil)
1998-07-01
In this paper, is presented a new theoretical approach developed in order to determine by direct method, non iterative, the load flow among the N bus bar of a generic power system. This method has been used to, from a single line simplified system of a typical industrial substation, used in the petroleum and by products storage and transportation facilities, calculate the voltage drops at bus bars and motors terminals from starting of the electric motors, after defining active and reactive power expressions flowing among bus bars, as a function of their voltages, impedance of connecting cables and of the loads connected to them. (author)
International Nuclear Information System (INIS)
Geske, G.
1979-01-01
With the aid of two effective material parameters a simple expression is presented for the Bethe-Bloch-formula for the calculation of the collision stopping power of materials for fast electrons. The formula has been modified in order to include the density effect. The derivation was accomplished in connection with a formalism given by Kim. It was shown that the material dependence on the collision stopping power is entirely comprehended by the density and two effective material parameters. Thus a simple criterion is given for the comparison of materials as to their collision stopping power
Isofocusing lens with cylindrical electrodes for charged particle beam with finite emittance
International Nuclear Information System (INIS)
Shpak, E.V.; Smirnova, A.A.
1995-01-01
An axially symmetric lens, consisting of three cylindrical electrodes and designed for shaping the beams of charged particles with final emittance, is studied. The potentials on the lens electrodes, which ensure the maintenance of the crossover formed by the lens, are calculated. The dependences of the ratios of potentials on the lens electrodes are analyzed for different values of R 0 /R 0 1 ratios, where R 0 and R 1 are maximum values of initial values of coordinates and the slopes in the crossover, respectively. 4 refs.; 3 figs
Shchinnikov, P. A.; Safronov, A. V.
2014-12-01
General principles of a procedure for matching energy balances of thermal power plants (TPPs), whose use enhances the accuracy of information-measuring systems (IMSs) during calculations of performance characteristics (PCs), are stated. To do this, there is the possibility for changing values of measured and calculated variables within intervals determined by measurement errors and regulations. An example of matching energy balances of the thermal power plants with a T-180 turbine is made. The proposed procedure allows one to reduce the divergence of balance equations by 3-4 times. It is shown also that the equipment operation mode affects the profit deficiency. Dependences for the divergence of energy balances on the deviation of input parameters and calculated data for the fuel economy before and after matching energy balances are represented.
International Nuclear Information System (INIS)
Bhatnagar, S.; Mahecha, J.
2008-09-01
We have employed the framework of Bethe-Salpeter equation under Covariant Instantaneous Ansatz to calculate the leptonic decay constants of unequal mass pseudoscalar mesons. In the Dirac structure of BS wave function, the covariants are incorporated from their complete set in accordance with a recently proposed power counting rule, order-by-order in powers of inverse of meson mass. The decay constants are calculated incorporating both Leading Order (LO) as well as Next-to-leading Order (NLO) Dirac covariants. The contribution of both LO as well as NLO covariants to decay constants are studied in detail in this paper. The results are found to improve dramatically, and hence validating the power counting rule which also provides a practical means of incorporating Dirac covariants in the BS wave function of a hadron. (author)
Fully automated laser ray tracing system to measure changes in the crystalline lens GRIN profile.
Qiu, Chen; Maceo Heilman, Bianca; Kaipio, Jari; Donaldson, Paul; Vaghefi, Ehsan
2017-11-01
Measuring the lens gradient refractive index (GRIN) accurately and reliably has proven an extremely challenging technical problem. A fully automated laser ray tracing (LRT) system was built to address this issue. The LRT system captures images of multiple laser projections before and after traversing through an ex vivo lens. These LRT images, combined with accurate measurements of the lens geometry, are used to calculate the lens GRIN profile. Mathematically, this is an ill-conditioned problem; hence, it is essential to apply biologically relevant constraints to produce a feasible solution. The lens GRIN measurements were compared with previously published data. Our GRIN retrieval algorithm produces fast and accurate measurements of the lens GRIN profile. Experiments to study the optics of physiologically perturbed lenses are the future direction of this research.
Crystalline lens radioprotectors
International Nuclear Information System (INIS)
Belkacemi, Y.; Pasquier, D.; Castelain, B.; Lartigau, E.; Warnet, J.M.
2003-01-01
During more than a half of century, numerous compounds have been tested in different models against radiation-induced cataract. In this report, we will review the radioprotectors that have been already tested for non-human crystalline lens protection. We will focus on the most important published studies in this topic and the mechanisms of cyto-protection reported in. vitro and in. vivo from animals. The most frequent mechanisms incriminated in the cyto-protective effect are: free radical scavenging, limitation of lipid peroxidation, modulation of cycle progression increase of intracellular reduced glutathione pool, reduction of DNA strand breaks and limitation of apoptotic cell death. Arnifostine (or Ethyol) and anethole dithiolethione (or Sulfarlem), already used clinically as chemo- and radio-protectants, could be further test?r for ocular radioprotection particularly for radiation-induced cataract. (author)
International Nuclear Information System (INIS)
Conley, Ray; Liu Chian; Qian Jun; Kewish, Cameron M.; Macrander, Albert T.; Yan Hanfei; Maser, Joerg; Kang, Hyon Chol; Stephenson, G. Brian
2008-01-01
A multilayer Laue lens (MLL) is an x-ray focusing optic fabricated from a multilayer structure consisting of thousands of layers of two different materials produced by thin-film deposition. The sequence of layer thicknesses is controlled to satisfy the Fresnel zone plate law and the multilayer is sectioned to form the optic. An improved MLL geometry can be created by growing each layer with an in-plane thickness gradient to form a wedge, so that every interface makes the correct angle with the incident beam for symmetric Bragg diffraction. The ultimate hard x-ray focusing performance of a wedged MLL has been predicted to be significantly better than that of a nonwedged MLL, giving subnanometer resolution with high efficiency. Here, we describe a method to deposit the multilayer structure needed for an ideal wedged MLL and report our initial deposition results to produce these structures
Energy Technology Data Exchange (ETDEWEB)
Diaz, Daniel Suescun
2007-07-01
This work presents two new methods for the solution of the inverse point kinetics equation. The first method is based on the integration by parts of the integral of the inverse point kinetics equation, which results in a power series in terms of the nuclear power in time dependence. Applying some conditions to the nuclear power, the reactivity is represented as first and second derivatives of this nuclear power. This new calculation method for reactivity has special characteristics, amongst which the possibility of using different sampling periods, and the possibility of restarting the calculation, after its interruption associated it with a possible equipment malfunction, allowing the calculation of reactivity in a non-continuous way. Apart from this reactivity can be obtained with or without dependency on the nuclear power memory. The second method is based on the Laplace transform of the point kinetics equations, resulting in an expression equivalent to the inverse kinetics equation as a function of the power history. The reactivity can be written in terms of the summation of convolution with response to impulse, characteristic of a linear system. For its digital form the Z-transform is used, which is the discrete version of the Laplace transform. In this method it can be pointed out that the linear part is equivalent to a filter named Finite Impulse Response (Fir). The Fir filter will always be, stable and non-varying in time, and, apart from this, it can be implemented in the non-recursive way. This type of implementation does not require feedback, allowing the calculation of reactivity in a continuous way. The proposed methods were validated using signals with random noise and showing the relationship between the reactivity difference and the degree of the random noise. (author)
DEFF Research Database (Denmark)
Chen, Shuheng; Hu, Weihao; Chen, Zhe
2014-01-01
Based on generalized chain-table storage structure (GCTSS), a novel power flow method is proposed, which can be used to solve the power flow of weakly meshed distribution networks with multiple distributed generators (DGs). GCTSS is designed based on chain-table technology and its target is to de......Based on generalized chain-table storage structure (GCTSS), a novel power flow method is proposed, which can be used to solve the power flow of weakly meshed distribution networks with multiple distributed generators (DGs). GCTSS is designed based on chain-table technology and its target...... is to describe the topology of radial distribution networks with a clear logic and a small memory size. The strategies of compensating the equivalent currents of break-point branches and the reactive power outputs of PV-type DGs are presented on the basis of superposition theorem. Their formulations...... are simplified to be the final multi-variable linear functions. Furthermore, an accelerating factor is applied to the outer-layer reactive power compensation for improving the convergence procedure. Finally, the proposed power flow method is performed in program language VC++ 6.0, and numerical tests have been...
Fan, Chunpeng; Zhang, Donghui
2012-01-01
Although the Kruskal-Wallis test has been widely used to analyze ordered categorical data, power and sample size methods for this test have been investigated to a much lesser extent when the underlying multinomial distributions are unknown. This article generalizes the power and sample size procedures proposed by Fan et al. ( 2011 ) for continuous data to ordered categorical data, when estimates from a pilot study are used in the place of knowledge of the true underlying distribution. Simulations show that the proposed power and sample size formulas perform well. A myelin oligodendrocyte glycoprotein (MOG) induced experimental autoimmunce encephalomyelitis (EAE) mouse study is used to demonstrate the application of the methods.
Compliance among soft contact lens wearers.
Kuzman, Tomislav; Kutija, Marija Barisić; Masnec, Sanja; Jandroković, Sonja; Mrazovac, Danijela; Jurisić, Darija; Skegro, Ivan; Kalauz, Miro; Kordić, Rajko
2014-12-01
Contact lens compliance is proven to be crucial for preventing lens wear-related complications because of the interdependence of the steps in lens care regime and their influence on lens system microbial contamination. Awareness of the patients' lens handling compliance as well as correct recognition of non-compliant behaviours is the basis for creating more targeted strategies for patient education. The aim of this study was to investigate compliance among soft contact lens (SCL) wearers in different aspects of lens care handling and wearing habits. In our research 50 asymptomatic lens wearers filled out a questionnaire containing demographic data, lens type, hygiene and wearing habits, lenses and lens care system replacement schedule and self-evaluation of contact lens handling hygiene. We established criteria of compliance according to available manufacturer's recommendations, prior literature and our clinical experience. Only 2 (4%) of patients were fully compliant SCL wearers. The most common non-compliant behaviours were insufficient lens solution soaking time (62%), followed by failure to daily exchange lens case solution and showering while wearing lenses. 44% of patients reported storing lenses in saline solution. Mean lens storage case replacement was 3.6 months, with up to 78% patients replacing lens case at least once in 3 months. Average grade in self evaluating level of compliance was very good (4 +/- 0.78) (from 1-poor level of hygiene to 5-great level of hygiene). Lens wearers who reported excessive daily lens wear and more than 10 years of lens wearing experience were also found to be less compliant with other lens system care procedures. (t = -2.99, df=47, p rate, self grading was relatively high. Therefore, these results indicate the need for patient education and encouragement of better lens wearing habits and all of the lens maintenance steps at each patient visit.
Contact Lens-Related Eye Infections
... Español Eye Health / Eye Health A-Z Contact Lens-Related Eye Infections Sections Contact Lens-Related Eye ... Six Steps to Avoid Contact Lens Infections Contact Lens-Related Eye Infections Leer en Español: Infecciones relacionadas ...
21 CFR 886.1375 - Bagolini lens.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Bagolini lens. 886.1375 Section 886.1375 Food and... OPHTHALMIC DEVICES Diagnostic Devices § 886.1375 Bagolini lens. (a) Identification. A Bagolini lens is a device that consists of a plane lens containing almost imperceptible striations that do not obscure...
Straylight Measurements in Contact Lens Wear
van der Meulen, Ivanka J. E.; Engelbrecht, Leonore A.; van Vliet, Johannes M. J.; Lapid-Gortzak, Ruth; Nieuwendaal, Carla P.; Mourits, Maarten P.; Schlingemann, Reinier O.; van den Berg, Thomas J. T. P.
2010-01-01
Purpose: (1) To quantify the effect of contact lens wear on straylight in rigid and soft contact lens wearers and (2) to relate findings to morphological changes and subjective complaints. Methods: Straylight was measured using the Oculus C-Quant during contact lens wear and after contact lens
International Nuclear Information System (INIS)
Albendea, M.
2014-01-01
Iberdrola is developing a new application to calculate the inventory of radiological material, then of a hypothetical accident, with the name of inventory. This application allows you to calculate the inventory isotopic, analysers and accurate thermal of all or part of the nucleus of the plant of Cofrentes, even of any single element, based on its history of irradiation and specific periods of decay, since the reactor at any time after the shutdown. (Author)
International Nuclear Information System (INIS)
Karlberg, O.
1995-02-01
Doses to critical groups from the activity released from swedish reactors were modelled in 1983. In this report these calculations are compared to doses calculated (using the same assumptions as in the 1983 model) from the activity measured in the water recipient. The study shows that the model overestimates activity in biota and sediments, which was expected, since the model was constructed to be conservative. 13 refs, 5 figs, 6 tabs
Directory of Open Access Journals (Sweden)
Ronald de Vlaming
2017-01-01
Full Text Available Large-scale genome-wide association results are typically obtained from a fixed-effects meta-analysis of GWAS summary statistics from multiple studies spanning different regions and/or time periods. This approach averages the estimated effects of genetic variants across studies. In case genetic effects are heterogeneous across studies, the statistical power of a GWAS and the predictive accuracy of polygenic scores are attenuated, contributing to the so-called 'missing heritability'. Here, we describe the online Meta-GWAS Accuracy and Power (MetaGAP calculator (available at www.devlaming.eu which quantifies this attenuation based on a novel multi-study framework. By means of simulation studies, we show that under a wide range of genetic architectures, the statistical power and predictive accuracy provided by this calculator are accurate. We compare the predictions from the MetaGAP calculator with actual results obtained in the GWAS literature. Specifically, we use genomic-relatedness-matrix restricted maximum likelihood to estimate the SNP heritability and cross-study genetic correlation of height, BMI, years of education, and self-rated health in three large samples. These estimates are used as input parameters for the MetaGAP calculator. Results from the calculator suggest that cross-study heterogeneity has led to attenuation of statistical power and predictive accuracy in recent large-scale GWAS efforts on these traits (e.g., for years of education, we estimate a relative loss of 51-62% in the number of genome-wide significant loci and a relative loss in polygenic score R2 of 36-38%. Hence, cross-study heterogeneity contributes to the missing heritability.
Kolotkov, Gennady A.; Penin, Sergei
2017-11-01
The paper examines an update of comparative analysis of radionuclides released into the atmosphere from Beloyarsk nuclear power plant with fast-neutron reactor for nine years in a row, from 2008 to 2016. It has been shown that the main radionuclides throw out into the atmosphere from Beloyarsk nuclear power plant are beta-active radionuclides. Based on data releases of the RPA "Typhoon", it has been conclude that radiation situation become worse insignificantly; beside on the new reactor BN-800 was put in operation in 2016. Using Spencer-Fano's equation, it was carried out the summary spectrum of emitted radionuclides. On example of Beloyarsk nuclear power plant, it was considered a question about ability of remote detection of raised radioactivity in the atmospheric radioactive plume. It has been shown that it possible to detect raised radioactivity in the emission plume from Beloyarsk nuclear power plant.
Development of a 3D finite element model of lens microcirculation
Directory of Open Access Journals (Sweden)
Vaghefi Ehsan
2012-09-01
Full Text Available Abstract Background It has been proposed that in the absence of a blood supply, the ocular lens operates an internal microcirculation system. This system delivers nutrients, removes waste products and maintains ionic homeostasis in the lens. The microcirculation is generated by spatial differences in membrane transport properties; and previously has been modelled by an equivalent electrical circuit and solved analytically. While effective, this approach did not fully account for all the anatomical and functional complexities of the lens. To encapsulate these complexities we have created a 3D finite element computer model of the lens. Methods Initially, we created an anatomically-correct representative mesh of the lens. We then implemented the Stokes and advective Nernst-Plank equations, in order to model the water and ion fluxes respectively. Next we complemented the model with experimentally-measured surface ionic concentrations as boundary conditions and solved it. Results Our model calculated the standing ionic concentrations and electrical potential gradients in the lens. Furthermore, it generated vector maps of intra- and extracellular space ion and water fluxes that are proposed to circulate throughout the lens. These fields have only been measured on the surface of the lens and our calculations are the first 3D representation of their direction and magnitude in the lens. Conclusion Values for steady state standing fields for concentration and electrical potential plus ionic and fluid fluxes calculated by our model exhibited broad agreement with observed experimental values. Our model of lens function represents a platform to integrate new experimental data as they emerge and assist us to understand how the integrated structure and function of the lens contributes to the maintenance of its transparency.
Immunohistochemical studies of lens crystallins in the dysgenetic lens (dyl) mutant mice
Brahma, S.K.; Sanyal, S.
1984-01-01
The lens in the dyl mutant mice shows a persistent lens-ectodermal connection as well as degeneration and extrusion of lens materials after the initial differentiation of the fibres. Immunohistochemical investigation of the ontogeny of the lens crystallins in this developing mutant lens has been
International Nuclear Information System (INIS)
Ahmed, S. A.; Peter, J. K.; Semmler, W.; Shultis, J. K.
2007-01-01
By measuring neutron fluxes at different locations throughout a core, it's possible to derive the power-density profile P k (W cm - 3), at an axial depth z of fuel rod k. Micro-pocket fission detectors (MPFD) have been fabricated to perform such in-core neutron flux measurements. The purpose of this study is to develop a mathematical model to obtain axial power density distributions in the fuel rods from the in-core responses of the MPFDs
The effect of a transient thermal lens on the Nd:YVO4 laser output
International Nuclear Information System (INIS)
Yi, Jonghoon; Lee, Kangin; Kim, Youngjung; Kwon, Jinhyuk
2010-01-01
A Nd:YVO 4 laser was pumped by using a diode laser, which has maximum cw pump power of 1 W. The driving current of the diode laser was modulated to have a square waveform. The Nd:YVO 4 laser output power increased linearly and then saturated when the quasi-cw diode laser pulse was focused on the crystal. When the same diode laser pulse was applied on the crystal, transient thermal lensing in the Nd:YVO 4 crystal was monitored by using a probe beam in a non-lasing condition. The TEM 00 mode diameter of the laser was calculated as a function of the focal length of the thermal lens. The results indicated that transient thermal lensing in the crystal was the main cause of the temporally varying output.
Adjustable internal structure for reconstructing gradient index profile of crystalline lens.
Bahrami, Mehdi; Goncharov, Alexander V; Pierscionek, Barbara K
2014-03-01
Employing advanced technologies in studying the crystalline lens of the eye has improved our understanding of the refractive index gradient of the lens. Reconstructing and studying such a complex structure requires models with adaptable internal geometry that can be altered to simulate geometrical and optical changes of the lens with aging. In this Letter, we introduce an optically well-defined, geometrical structure for modeling the gradient refractive index profile of the crystalline lens with the advantage of an adjustable internal structure that is not available with existing models. The refractive index profile assigned to this rotationally symmetric geometry is calculated numerically, yet it is shown that this does not limit the model. The study provides a basis for developing lens models with sophisticated external and internal structures without the need for analytical solutions to calculate refractive index profiles.
An all-silicone zoom lens in an optical imaging system
International Nuclear Information System (INIS)
Zhao Cun-Hua
2013-01-01
An all-silicone zoom lens is fabricated. A tunable metal ringer is fettered around the side edge of the lens. A nylon rope linking a motor is tied, encircling the notch in the metal ringer. While the motor is operating, the rope can shrink or release to change the focal length of the lens. A calculation method is developed to obtain the focal length and the zoom ratio. The testing is carried out in succession. The testing values are compared with the calculated ones, and they tally with each other well. Finally, the imaging performance of the all-silicone lens is demonstrated. The all-silicone lens has potential uses in cellphone cameras, notebook cameras, micro monitor lenses, etc. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
An all-silicone zoom lens in an optical imaging system
Zhao, Cun-Hua
2013-09-01
An all-silicone zoom lens is fabricated. A tunable metal ringer is fettered around the side edge of the lens. A nylon rope linking a motor is tied, encircling the notch in the metal ringer. While the motor is operating, the rope can shrink or release to change the focal length of the lens. A calculation method is developed to obtain the focal length and the zoom ratio. The testing is carried out in succession. The testing values are compared with the calculated ones, and they tally with each other well. Finally, the imaging performance of the all-silicone lens is demonstrated. The all-silicone lens has potential uses in cellphone cameras, notebook cameras, micro monitor lenses, etc.
Lightweight Inexpensive Ozone Lidar Telescope Using a Plastic Fresnel Lens
DeYoung, Russell J.; Notari, Anthony; Carrion, William; Pliutau, Denis
2014-01-01
An inexpensive lightweight ozone lidar telescope was designed, constructed and operated during an ozone lidar field campaign. This report summarizes the design parameters and performance of the plastic Fresnel lens telescope and shows the ozone lidar performance compared to Zemax calculations.
Bilingual child acquisition through the lens of sociolinguistic approaches
Cornips, L.; Miller, David; Bayram, Fatih; Rothman, Jason; Serratrice, Ludovica
2018-01-01
This paper entails a perspective on bilingual child acquisition through the lens of sociolinguistic approaches. A discussion of the concepts of monolingual language ideology and power dynamics is undertaken in order to reveal their important consequences on studying bilingual child acquisition, in
Contact Lens Related Corneal Ulcer
Loh, KY; Agarwal, P
2010-01-01
A corneal ulcer caused by infection is one of the major causes of blindness worldwide. One of the recent health concerns is the increasing incidence of corneal ulcers associated with contact lens user especially if the users fail to follow specific instruction in using their contact lenses. Risk factors associated with increased risk of contact lens related corneal ulcers are: overnight wear, long duration of continuous wear, lower socio-economic classes, smoking, dry eye and poor hygiene. Th...
Liu, Chuyu [Newport News, VA; Zhang, Shukui [Yorktown, VA
2011-10-04
A single lens bullet-shaped laser beam shaper capable of redistributing an arbitrary beam profile into any desired output profile comprising a unitary lens comprising: a convex front input surface defining a focal point and a flat output portion at the focal point; and b) a cylindrical core portion having a flat input surface coincident with the flat output portion of the first input portion at the focal point and a convex rear output surface remote from the convex front input surface.
Directory of Open Access Journals (Sweden)
Niancheng Zhou
2014-08-01
Full Text Available The influence of electric vehicle charging stations on power grid harmonics is becoming increasingly significant as their presence continues to grow. This paper studies the operational principles of the charging current in the continuous and discontinuous modes for a three-phase uncontrolled rectification charger with a passive power factor correction link, which is affected by the charging power. A parameter estimation method is proposed for the equivalent circuit of the charger by using the measured characteristic AC (Alternating Current voltage and current data combined with the charging circuit constraints in the conduction process, and this method is verified using an experimental platform. The sensitivity of the current harmonics to the changes in the parameters is analyzed. An analytical harmonic model of the charging station is created by separating the chargers into groups by type. Then, the harmonic current amplification caused by the shunt active power filter is researched, and the analytical formula for the overload factor is derived to further correct the capacity of the shunt active power filter. Finally, this method is validated through a field test of a charging station.
Velzel, Chris
2014-01-01
A Course in Lens Design is an instruction in the design of image-forming optical systems. It teaches how a satisfactory design can be obtained in a straightforward way. Theory is limited to a minimum, and used to support the practical design work. The book introduces geometrical optics, optical instruments and aberrations. It gives a description of the process of lens design and of the strategies used in this process. Half of its content is devoted to the design of sixteen types of lenses, described in detail from beginning to end. This book is different from most other books on lens design because it stresses the importance of the initial phases of the design process: (paraxial) lay-out and (thin-lens) pre-design. The argument for this change of accent is that in these phases much information can be obtained about the properties of the lens to be designed. This information can be used in later phases of the design. This makes A Course in Lens Design a useful self-study book, and a suitable basis for an intro...
Froud, Robert; Rajendran, Dévan; Patel, Shilpa; Bright, Philip; Bjørkli, Tom; Eldridge, Sandra; Buchbinder, Rachelle; Underwood, Martin
2017-06-01
A systematic review of nonspecific low back pain trials published between 1980 and 2012. To explore what proportion of trials have been powered to detect different bands of effect size; whether there is evidence that sample size in low back pain trials has been increasing; what proportion of trial reports include a sample size calculation; and whether likelihood of reporting sample size calculations has increased. Clinical trials should have a sample size sufficient to detect a minimally important difference for a given power and type I error rate. An underpowered trial is one within which probability of type II error is too high. Meta-analyses do not mitigate underpowered trials. Reviewers independently abstracted data on sample size at point of analysis, whether a sample size calculation was reported, and year of publication. Descriptive analyses were used to explore ability to detect effect sizes, and regression analyses to explore the relationship between sample size, or reporting sample size calculations, and time. We included 383 trials. One-third were powered to detect a standardized mean difference of less than 0.5, and 5% were powered to detect less than 0.3. The average sample size was 153 people, which increased only slightly (∼4 people/yr) from 1980 to 2000, and declined slightly (∼4.5 people/yr) from 2005 to 2011 (P pain trials and the reporting of sample size calculations may need to be increased. It may be justifiable to power a trial to detect only large effects in the case of novel interventions. 3.
Sarracino, Marcello
1941-01-01
The present article deals with what is considered to be a simpler and more accurate method of determining, from the results of bench tests under approved rating conditions, the power at altitude of a supercharged aircraft engine, without application of correction formulas. The method of calculating the characteristics at altitude, of supercharged engines, based on the consumption of air, is a more satisfactory and accurate procedure, especially at low boost pressures.
Effect of interface reflection in pseudophakic eyes with an additional refractive intraocular lens.
Schrecker, Jens; Zoric, Katja; Meßner, Arthur; Eppig, Timo
2012-09-01
To compare the surface reflections in a pseudophakic model eye with and without a monofocal additional refractive intraocular lens (add-on IOL). Department of Ophthalmology, Rudolf-Virchow-Klinikum Glauchau, Glauchau, and Experimental Ophthalmology, Saarland University, Homburg, Germany. Experimental study. The Liou and Brennan model eye was used to determine the retinal surface reflections in a pseudophakic model eye with and without an add-on IOL. The crystalline lens of the model eye was replaced by (1) a standard posterior chamber IOL (PC IOL) with a refractive power of 22.0 diopters (D) and (2) a PC IOL and an add-on IOL with refractive powers of 19.0 D and 2.5 D, respectively. To theoretically estimate the impact of the reflected images to visual impression, the signal-to-noise ratio (SNR) was calculated under 2 conditions: without and with straylight and double reflection effects. Compared with the pseudophakic model eye without an add-on IOL, the pseudophakic model eye with an add-on IOL showed no relevant differences in the SNR under both conditions. Findings indicate that implantation of monofocal add-on IOLs will not induce relevant additional disturbing glare compared with conventional pseudophakia. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
Vysotskaya, Anna; Kolvakh, Oleg; Stoner, Greg
2016-01-01
The aim of this paper is to describe the innovative teaching approach used in the Southern Federal University, Russia, to teach accounting via a form of matrix mathematics. It thereby contributes to disseminating the technique of teaching to solve accounting cases using mutual calculations to a worldwide audience. The approach taken in this course…
International Nuclear Information System (INIS)
Lima Filho, R.M.; Oliveira, L.F.S. de
1984-01-01
A general method for the calculation of the time evolution of source terms related to irradiated fuel is presented. Some applications are discussed which indicated that the method can provide important informations for the engineering design and safety analysis of a temporary storage facility of irradiated fuel elements. (Author) [pt
Directory of Open Access Journals (Sweden)
Ryouhei eIshii
2014-06-01
Full Text Available Frontal midline theta rhythm (Fmθ appears widely distributed over medial prefrontal areas in EEG recordings, indicating focused attention. Although mental calculation is often used as an attention-demanding task, little has been reported on calculation-related activation in Fmθ experiments. In this study we used spatially filtered MEG and permutation analysis to precisely localize cortical generators of the magnetic counterpart of Fmθ, as well as other sources of oscillatory activity associated with mental calculation processing (i.e., arithmetic subtraction. Our results confirmed and extended earlier EEG/MEG studies indicating that Fmθ during mental calculation is generated in the dorsal anterior cingulate and adjacent medial prefrontal cortex. Mental subtraction was also associated with gamma event-related synchronization, as an index of activation, in right parietal regions subserving basic numerical processing and number-based spatial attention. Gamma event-related desynchronization appeared in the right lateral prefrontal cortex, likely representing a mechanism to interrupt neural activity that can interfere with the ongoing cognitive task.
International Nuclear Information System (INIS)
Kokhanenko, I.K.; Zajtsev, A.A.
1993-01-01
A method for plasma anomalous heating by SHF radiation with variable power characteristics is considered. On the base of automodel system theory it is shown a possibility of providing for controlled plasma burning in a mode with 'sharpening'. Anomalous phenomena, appeared in experimental investigations of the SHF discharge, are explained
International Nuclear Information System (INIS)
Cheong, Jae Hak
2017-01-01
In order to review if present detection limits of radionuclides in liquid effluent from nuclear power plants are effective enough to warrant compliance with regulatory discharge limits, a risk-based approach is developed to derive a new detection limit for each radionuclide based on radiological criteria. Equations and adjustment factors are also proposed to discriminate the validity of the detection limits for multiple radionuclides in the liquid effluent with or without consideration of the nuclide composition. From case studies to three nuclear power plants in Korea with actual operation data from 2006 to 2015, the present detection limits have turned out to be effective for Hanul Unit 1 but may not be sensitive enough for Kori Unit 1 (8 out of 14 radionuclides) and Wolsong Unit 1 (9 out of 42 radionuclides). However, it is shown that the present detection limits for the latter two nuclear power plants can be justified, if credit is given to the radionuclide composition. Otherwise, consideration should be given to adjustment of the present detection limits. The risk-based approach of this study can be used to determine the validity of established detection limits of a specific nuclear power plant. (author)
Goldmann applanation tonometry over daily disposable contact lens: accuracy and safety of procedure.
Zeri, Fabrizio; Lupelli, Luigi; Formichella, Paolo; Masci, Carlo; Fletcher, Robert
2007-09-01
To study accuracy and safety, related to sensation (discomfort) and trauma, when using Goldmann applanation tonometry (GAT) on eyes wearing daily disposable soft contact lenses. The intra-ocular pressure (IOP) of 136 normal eyes of 68 subjects was measured by Goldmann tonometer. Measurements were made in one eye with a contact lens (hilafilcon A) without anaesthetic drops and then without the contact lens using one drop of 0.4% oxybuprocaine hydrochloride. Each contact lens used was identical as to back optic zone, back vertex power. Standard Goldmann procedure only was used for the fellow eye of each subject. Subjective sensation (discomfort) responses to both procedures were studied in a subgroup (66 eyes) using a scale of discomfort, from 1 (no sensation) to 5 (highest sensation). Epithelial staining after tonometry was evaluated for this subgroup. No significant differences were found for the IOP with and without contact lens (tcontact lens insertion, tonometry on contact lens and application of topical anaesthetic). Corneal epithelial staining following the standard tonometry procedure was significantly higher than following the procedure with a contact lens (pcontact lens is accurate, compared to the standard procedure and within the IOP's normal range studied here. Also using a contact lens results in less trauma whilst discomfort is similar.
Directory of Open Access Journals (Sweden)
Nikoo Hamzeh
2015-12-01
Full Text Available AIM: To assess lens thickness measurements with anterior segment-optical coherence tomography (AS-OCT in comparison with A-scan ultrasonography (A-scan US. METHODS: There were 218 adult subjects (218 eyes aged 59.2±9.2y enrolled in this prospective cross-sectional study. Forty-three eyes had open angles and 175 eyes had narrow angles. Routine ophthalmic exam was performed and nuclear opacity was graded using the Lens Opacities Classification System III (LOCS III. Lens thickness was measured by AS-OCT (Visante OCT, Carl Zeiss Meditec, Dublin, CA, USA. The highest quality image was selected for each eye and lens thickness was calculated using ImageJ software. Lens thickness was also measured by A-scan US. RESULTS: Interclass correlations showed a value of 99.7% for intra-visit measurements and 95.3% for inter-visit measurements. The mean lens thickness measured by AS-OCT was not significantly different from that of A-scan US (4.861±0.404 vs 4.866±0.351 mm, P=0.74. Lens thickness values obtained from the two instruments were highly correlated overall (Pearson correlation coefficient=0.81, P<0.001, and in all LOCS III specific subgroups except in grade 5 of nuclear opacity. Bland-Altman analysis revealed a 95% limit of agreement from -0.45 to 0.46 mm. Lens thickness difference between the two instruments became smaller as the lens thickness increased and AS-OCT yielded smaller values than A-scan US in thicker lens (β=-0.29, P<0.001 CONCLUSION: AS-OCT-derived lens thickness measurement is valid and comparable to the results obtained by A-scan US. It can be used as a reliable noncontact method for measuring lens thickness in adults with or without significant cataract.
International Nuclear Information System (INIS)
Garcia H, Carlos R.; Milian, Daniel
1997-01-01
In this paper the most remarkable results obtained in Cuba, for the Juragua Nuclear Power Plant (JNPP) in core fuel management, are shown. The main characteristic of the codes used to solve the usual sequence of neutron-physical calculations available in our code library are reported. The codes validation was based on estimative of their accuracy by inter comparing calculated and WWER-440 NPP's operation data. A brief summary of the extensive calculations carried out for the JNPP Preliminary Safety Report elaboration is presented. This report is one of the requisites demanded by the Cuban Nuclear Agency for issuing the General Permission for restart works in the plant. (author). 12 refs., 4 figs., 6 tabs