WorldWideScience

Sample records for accuracy

  1. Target Price Accuracy

    Alexander G. Kerl

    2011-01-01

    This study analyzes the accuracy of forecasted target prices within analysts’ reports. We compute a measure for target price forecast accuracy that evaluates the ability of analysts to exactly forecast the ex-ante (unknown) 12-month stock price. Furthermore, we determine factors that explain this accuracy. Target price accuracy is negatively related to analyst-specific optimism and stock-specific risk (measured by volatility and price-to-book ratio). However, target price accuracy is positive...

  2. Relative accuracy evaluation.

    Yan Zhang

    Full Text Available The quality of data plays an important role in business analysis and decision making, and data accuracy is an important aspect in data quality. Thus one necessary task for data quality management is to evaluate the accuracy of the data. And in order to solve the problem that the accuracy of the whole data set is low while a useful part may be high, it is also necessary to evaluate the accuracy of the query results, called relative accuracy. However, as far as we know, neither measure nor effective methods for the accuracy evaluation methods are proposed. Motivated by this, for relative accuracy evaluation, we propose a systematic method. We design a relative accuracy evaluation framework for relational databases based on a new metric to measure the accuracy using statistics. We apply the methods to evaluate the precision and recall of basic queries, which show the result's relative accuracy. We also propose the method to handle data update and to improve accuracy evaluation using functional dependencies. Extensive experimental results show the effectiveness and efficiency of our proposed framework and algorithms.

  3. Relative accuracy evaluation.

    Zhang, Yan; Wang, Hongzhi; Yang, Zhongsheng; Li, Jianzhong

    2014-01-01

    The quality of data plays an important role in business analysis and decision making, and data accuracy is an important aspect in data quality. Thus one necessary task for data quality management is to evaluate the accuracy of the data. And in order to solve the problem that the accuracy of the whole data set is low while a useful part may be high, it is also necessary to evaluate the accuracy of the query results, called relative accuracy. However, as far as we know, neither measure nor effective methods for the accuracy evaluation methods are proposed. Motivated by this, for relative accuracy evaluation, we propose a systematic method. We design a relative accuracy evaluation framework for relational databases based on a new metric to measure the accuracy using statistics. We apply the methods to evaluate the precision and recall of basic queries, which show the result's relative accuracy. We also propose the method to handle data update and to improve accuracy evaluation using functional dependencies. Extensive experimental results show the effectiveness and efficiency of our proposed framework and algorithms. PMID:25133752

  4. Rethinking Empathic Accuracy

    Meadors, Joshua

    2014-01-01

    The present study is a methodological examination of the implicit empathic accuracy measure introduced by Zaki, Ochsner, and Bolger (2008). Empathic accuracy (EA) is defined as the ability to understand another person's thoughts and feelings (Ickes, 1993). Because this definition is similar to definitions of cognitive empathy (e.g., Shamay-Tsoory, 2011) and because affective empathy does not appear to be related to empathic accuracy (Zaki et al., 2008), the Basic Empathy Scale--which measures...

  5. The Truth about Accuracy

    Buekens, Filip; Truyen, Frederik

    2014-01-01

    When we evaluate the outcomes of investigative actions as justified or unjustified, good or bad, rational or irrational, we make, in a broad sense of the term, evaluative judgments about them. We look at operational accuracy as a desirable and evaluable quality of the outcomes and explore how the concepts of accuracy and precision, on the basis of insights borrowed from pragmatics and measurement theory, can be seen to do useful work in epistemology. Operational accuracy (but not metaphysical...

  6. Diagnosing Eyewitness Accuracy

    Russ, Andrew

    2015-01-01

    Eyewitnesses frequently mistake innocent people for the perpetrator of an observed crime. Such misidentifications have led to the wrongful convictions of many people. Despite this, no reliable method yet exists to determine eyewitness accuracy. This thesis explored two new experimental methods for this purpose. Chapter 2 investigated whether repetition priming can measure prior exposure to a target and compared this with observers’ explicit eyewitness accuracy. Across three experiments slower...

  7. Accuracy of Approximate Eigenstates

    Lucha, Wolfgang; Lucha, Wolfgang

    2000-01-01

    Besides perturbation theory, which requires, of course, the knowledge of the exact unperturbed solution, variational techniques represent the main tool for any investigation of the eigenvalue problem of some semibounded operator H in quantum theory. For a reasonable choice of the employed trial subspace of the domain of H, the lowest eigenvalues of H usually can be located with acceptable precision whereas the trial-subspace vectors corresponding to these eigenvalues approximate, in general, the exact eigenstates of H with much less accuracy. Accordingly, various measures for the accuracy of the approximate eigenstates derived by variational techniques are scrutinized. In particular, the matrix elements of the commutator of the operator H and (suitably chosen) different operators, with respect to degenerate approximate eigenstates of H obtained by some variational method, are proposed here as new criteria for the accuracy of variational eigenstates. These considerations are applied to that Hamiltonian the eig...

  8. Diagnostic test accuracy

    Campbell, Jared M.; Klugar, Miloslav; Ding, Sandrine; Carmody, Dennis P.; Håkonsen, Sasja Jul; Jadotte, Yuri T.; White, Sarahlouise; Munn, Zachary

    2015-01-01

    in providing methodological guidance for the conduct of systematic reviews and has developed methods and guidance for reviewers conducting systematic reviews of studies of diagnostic test accuracy. Diagnostic tests are used to identify the presence or absence of a condition for the purpose of...... developing an appropriate treatment plan. Owing to demands for improvements in speed, cost, ease of performance, patient safety, and accuracy, new diagnostic tests are continuously developed, and there are often several tests available for the diagnosis of a particular condition. In order to provide the...... evidence necessary for clinicians and other healthcare professionals to make informed decisions regarding the optimum test to use, primary studies need to be carried out on the accuracy of diagnostic tests and the results of these studies synthesized through systematic review. The Joanna Briggs Institute...

  9. The Accuracy of Multiples

    Stauropoulos Antonios

    2011-01-01

    Full Text Available Problem statement: Equity valuation with the use of multiples is widely used by academics and practitioners concerning its functionality. This study aims to explore the sensitivity of three multiples in terms of accuracy. Approach: Price-to-Sales (P/S multiple, the price-to-book value of equity (P/B multiple and the Price-to-Earnings (P/E multiple are three multiples under consideration, using both current and one-year-ahead earnings forecasts. Results: Evidence of empirical results show that, the multiples P/mdfy1 and P/mnfy1 are effective in terms of accuracy, with their means being negatively biased and their medians being positively biased. Finally, current earnings are identified as more appropriate value driver for the calculation of the P/E ratio by terms of accuracy. The results can be considered as reliable owing to the large sample and the procedure followed for its selection. Conclusion: This study offers a better understanding of the valuation approach through the use of multiples, in order analysts assumption to be more carefully and properly chosen and their results to be more accurately produced.

  10. Overlay accuracy fundamentals

    Kandel, Daniel; Levinski, Vladimir; Sapiens, Noam; Cohen, Guy; Amit, Eran; Klein, Dana; Vakshtein, Irina

    2012-03-01

    Currently, the performance of overlay metrology is evaluated mainly based on random error contributions such as precision and TIS variability. With the expected shrinkage of the overlay metrology budget to interaction with the metrology technology, as the main source of overlay inaccuracy. The most important type of mark imperfection is mark asymmetry. Overlay mark asymmetry leads to a geometrical ambiguity in the definition of overlay, which can be ~1nm or less. It is shown theoretically and in simulations that the metrology may enhance the effect of overlay mark asymmetry significantly and lead to metrology inaccuracy ~10nm, much larger than the geometrical ambiguity. The analysis is carried out for two different overlay metrology technologies: Imaging overlay and DBO (1st order diffraction based overlay). It is demonstrated that the sensitivity of DBO to overlay mark asymmetry is larger than the sensitivity of imaging overlay. Finally, we show that a recently developed measurement quality metric serves as a valuable tool for improving overlay metrology accuracy. Simulation results demonstrate that the accuracy of imaging overlay can be improved significantly by recipe setup optimized using the quality metric. We conclude that imaging overlay metrology, complemented by appropriate use of measurement quality metric, results in optimal overlay accuracy.

  11. Accuracy of tablet splitting.

    McDevitt, J T; Gurst, A H; Chen, Y

    1998-01-01

    We attempted to determine the accuracy of manually splitting hydrochlorothiazide tablets. Ninety-four healthy volunteers each split ten 25-mg hydrochlorothiazide tablets, which were then weighed using an analytical balance. Demographics, grip and pinch strength, digit circumference, and tablet-splitting experience were documented. Subjects were also surveyed regarding their willingness to pay a premium for commercially available, lower-dose tablets. Of 1752 manually split tablet portions, 41.3% deviated from ideal weight by more than 10% and 12.4% deviated by more than 20%. Gender, age, education, and tablet-splitting experience were not predictive of variability. Most subjects (96.8%) stated a preference for commercially produced, lower-dose tablets, and 77.2% were willing to pay more for them. For drugs with steep dose-response curves or narrow therapeutic windows, the differences we recorded could be clinically relevant. PMID:9469693

  12. Reticence, Accuracy and Efficacy

    Oreskes, N.; Lewandowsky, S.

    2015-12-01

    James Hansen has cautioned the scientific community against "reticence," by which he means a reluctance to speak in public about the threat of climate change. This may contribute to social inaction, with the result that society fails to respond appropriately to threats that are well understood scientifically. Against this, others have warned against the dangers of "crying wolf," suggesting that reticence protects scientific credibility. We argue that both these positions are missing an important point: that reticence is not only a matter of style but also of substance. In previous work, Bysse et al. (2013) showed that scientific projections of key indicators of climate change have been skewed towards the low end of actual events, suggesting a bias in scientific work. More recently, we have shown that scientific efforts to be responsive to contrarian challenges have led scientists to adopt the terminology of a "pause" or "hiatus" in climate warming, despite the lack of evidence to support such a conclusion (Lewandowsky et al., 2015a. 2015b). In the former case, scientific conservatism has led to under-estimation of climate related changes. In the latter case, the use of misleading terminology has perpetuated scientific misunderstanding and hindered effective communication. Scientific communication should embody two equally important goals: 1) accuracy in communicating scientific information and 2) efficacy in expressing what that information means. Scientists should strive to be neither conservative nor adventurous but to be accurate, and to communicate that accurate information effectively.

  13. Current Concept of Geometrical Accuracy

    Görög Augustín; Görögová Ingrid

    2014-01-01

    Within the solving VEGA 1/0615/12 research project "Influence of 5-axis grinding parameters on the shank cutter´s geometric accuracy", the research team will measure and evaluate geometrical accuracy of the produced parts. They will use the contemporary measurement technology (for example the optical 3D scanners). During the past few years, significant changes have occurred in the field of geometrical accuracy. The objective of this contribution is to analyse the current standards in the fiel...

  14. Back-propagation of accuracy

    Senashova, M. Yu.; Gorban, A. N.; Wunsch II, D. C.

    2003-01-01

    In this paper we solve the problem: how to determine maximal allowable errors, possible for signals and parameters of each element of a network proceeding from the condition that the vector of output signals of the network should be calculated with given accuracy? "Back-propagation of accuracy" is developed to solve this problem. The calculation of allowable errors for each element of network by back-propagation of accuracy is surprisingly similar to a back-propagation of error, because it is...

  15. Diagnostic accuracy in virtual dermatopathology

    Mooney, E.; Kempf, W.; Jemec, G.B.E.;

    2012-01-01

    slides and photomicrographs with corresponding clinical photographs and information in a self-assessment examination format. Descriptive data analysis and comparison of groups were performed using a chi-square test. Results Diagnostic accuracy in dermatopathology using virtual dermatopathology or...... diagnostic accuracy of dermatopathologists and pathologists using photomicrographs vs. digitized images, through a self-assessment examination, and to elucidate assessment of virtual dermatopathology. Methods Forty-five dermatopathologists and pathologists received a randomized combination of 15 virtual...

  16. Current Concept of Geometrical Accuracy

    Görög Augustín

    2014-06-01

    Full Text Available Within the solving VEGA 1/0615/12 research project "Influence of 5-axis grinding parameters on the shank cutter´s geometric accuracy", the research team will measure and evaluate geometrical accuracy of the produced parts. They will use the contemporary measurement technology (for example the optical 3D scanners. During the past few years, significant changes have occurred in the field of geometrical accuracy. The objective of this contribution is to analyse the current standards in the field of geometric tolerance. It is necessary to bring an overview of the basic concepts and definitions in the field. It will prevent the use of outdated and invalidated terms and definitions in the field. The knowledge presented in the contribution will provide the new perspective of the measurement that will be evaluated according to the current standards.

  17. Current Concept of Geometrical Accuracy

    Görög, Augustín; Görögová, Ingrid

    2014-06-01

    Within the solving VEGA 1/0615/12 research project "Influence of 5-axis grinding parameters on the shank cutteŕs geometric accuracy", the research team will measure and evaluate geometrical accuracy of the produced parts. They will use the contemporary measurement technology (for example the optical 3D scanners). During the past few years, significant changes have occurred in the field of geometrical accuracy. The objective of this contribution is to analyse the current standards in the field of geometric tolerance. It is necessary to bring an overview of the basic concepts and definitions in the field. It will prevent the use of outdated and invalidated terms and definitions in the field. The knowledge presented in the contribution will provide the new perspective of the measurement that will be evaluated according to the current standards.

  18. Classification Accuracy Is Not Enough

    Sturm, Bob L.

    2013-01-01

    A recent review of the research literature evaluating music genre recognition (MGR) systems over the past two decades shows that most works (81\\%) measure the capacity of a system to recognize genre by its classification accuracy. We show here, by implementing and testing three categorically...... different state-of-the-art MGR systems, that classification accuracy does not necessarily reflect the capacity of a system to recognize genre in musical signals. We argue that a more comprehensive analysis of behavior at the level of the music is needed to address the problem of MGR, and that measuring...... classification accuracy obscures the aim of MGR: to select labels indistinguishable from those a person would choose....

  19. Improving Speaking Accuracy through Awareness

    Dormer, Jan Edwards

    2013-01-01

    Increased English learner accuracy can be achieved by leading students through six stages of awareness. The first three awareness stages build up students' motivation to improve, and the second three provide learners with crucial input for change. The final result is "sustained language awareness," resulting in ongoing…

  20. AMR, stability and higher accuracy

    Efforts to achieve better accuracy in numerical relativity have so far focused either on implementing second-order accurate adaptive mesh refinement or on defining higher order accurate differences and update schemes. Here, we argue for the combination, that is a higher order accurate adaptive scheme. This combines the power that adaptive gridding techniques provide to resolve fine scales (in addition to a more efficient use of resources) together with the higher accuracy furnished by higher order schemes when the solution is adequately resolved. To define a convenient higher order adaptive mesh refinement scheme, we discuss a few different modifications of the standard, second-order accurate approach of Berger and Oliger. Applying each of these methods to a simple model problem, we find these options have unstable modes. However, a novel approach to dealing with the grid boundaries introduced by the adaptivity appears stable and quite promising for the use of high order operators within an adaptive framework

  1. AMR, stability and higher accuracy

    Lehner, Luis [Department of Physics and Astronomy, Louisiana State University, 202 Nicholson Hall, Baton Rouge, Louisiana 70803-4001 (United States); Liebling, Steven L [Department of Physics, Long Island University-C W Post Campus, Brookville, New York 11548 (United States); Reula, Oscar [FaMAF, Universidad Nacional de Cordoba, Cordoba, 5000 (Argentina)

    2006-08-21

    Efforts to achieve better accuracy in numerical relativity have so far focused either on implementing second-order accurate adaptive mesh refinement or on defining higher order accurate differences and update schemes. Here, we argue for the combination, that is a higher order accurate adaptive scheme. This combines the power that adaptive gridding techniques provide to resolve fine scales (in addition to a more efficient use of resources) together with the higher accuracy furnished by higher order schemes when the solution is adequately resolved. To define a convenient higher order adaptive mesh refinement scheme, we discuss a few different modifications of the standard, second-order accurate approach of Berger and Oliger. Applying each of these methods to a simple model problem, we find these options have unstable modes. However, a novel approach to dealing with the grid boundaries introduced by the adaptivity appears stable and quite promising for the use of high order operators within an adaptive framework.

  2. GPS kinematics measurements accuracy testing

    Miroslav Šimčák; Vladimír Sedlák; Gabriela Nemcová

    2007-01-01

    In the paper accuracy of GPS kinematics measurements is analyzed. GPS (Global Positioning System) apparatus Stratus (Sokkia) and Pro Mark2 (Aschtech) were tested. Testing was realized on the points of the geodetic network – the testing station Badín stabilized in the Central Slovak Region nearby Banská Bystrica. The semikinematics method STOP and GO was realized from the kinematics GPS methods. The terrestrial geodetic measurements by means of using the total station Nicon 352 were also reali...

  3. Accuracy of the geodetic plans

    Kekec, Tomislav

    2011-01-01

    This thesis investigates whether it is possible to give an overall assessment of the accuracy of geodetic plan. The introductory part presents the legal basis of geodetic plan and its definition under the Regulations of Land Survey Maps and Topographic Key. The content of the geodetic plan and description of geodetic and surveying information sources which are the graphical part of geodetic plan are introduced in the second part. This part also describes the types of land survey plans, as the...

  4. Municipal water consumption forecast accuracy

    Fullerton, Thomas M.; Molina, Angel L.

    2010-06-01

    Municipal water consumption planning is an active area of research because of infrastructure construction and maintenance costs, supply constraints, and water quality assurance. In spite of that, relatively few water forecast accuracy assessments have been completed to date, although some internal documentation may exist as part of the proprietary "grey literature." This study utilizes a data set of previously published municipal consumption forecasts to partially fill that gap in the empirical water economics literature. Previously published municipal water econometric forecasts for three public utilities are examined for predictive accuracy against two random walk benchmarks commonly used in regional analyses. Descriptive metrics used to quantify forecast accuracy include root-mean-square error and Theil inequality statistics. Formal statistical assessments are completed using four-pronged error differential regression F tests. Similar to studies for other metropolitan econometric forecasts in areas with similar demographic and labor market characteristics, model predictive performances for the municipal water aggregates in this effort are mixed for each of the municipalities included in the sample. Given the competitiveness of the benchmarks, analysts should employ care when utilizing econometric forecasts of municipal water consumption for planning purposes, comparing them to recent historical observations and trends to insure reliability. Comparative results using data from other markets, including regions facing differing labor and demographic conditions, would also be helpful.

  5. Narrow-width approximation accuracy

    A study of general properties of the narrow-width approximation (NWA) with polarization/spin decorrelation is presented. We prove for sufficiently inclusive differential rates of arbitrary resonant decay or scattering processes with an on-shell intermediate state decaying via a cubic or quartic vertex that decorrelation effects vanish and the NWA is of order Γ. Its accuracy is then determined numerically for all resonant 3-body decays involving scalars, spin-1/2 fermions or vector bosons. We specialize the general results to MSSM benchmark scenarios. Significant off-shell corrections can occur - similar in size to QCD corrections. We qualify the configurations in which a combined consideration is advisable. For this purpose, we also investigate process-independent methods to improve the NWA

  6. Increasing Accuracy in Environmental Measurements

    Jacksier, Tracey; Fernandes, Adelino; Matthew, Matt; Lehmann, Horst

    2016-04-01

    Human activity is increasing the concentrations of green house gases (GHG) in the atmosphere which results in temperature increases. High precision is a key requirement of atmospheric measurements to study the global carbon cycle and its effect on climate change. Natural air containing stable isotopes are used in GHG monitoring to calibrate analytical equipment. This presentation will examine the natural air and isotopic mixture preparation process, for both molecular and isotopic concentrations, for a range of components and delta values. The role of precisely characterized source material will be presented. Analysis of individual cylinders within multiple batches will be presented to demonstrate the ability to dynamically fill multiple cylinders containing identical compositions without isotopic fractionation. Additional emphasis will focus on the ability to adjust isotope ratios to more closely bracket sample types without the reliance on combusting naturally occurring materials, thereby improving analytical accuracy.

  7. Data accuracy assessment using enterprise architecture

    Närman, Per; Holm, Hannes; Johnson, Pontus; König, Johan; Chenine, Moustafa; Ekstedt, Mathias

    2011-02-01

    Errors in business processes result in poor data accuracy. This article proposes an architecture analysis method which utilises ArchiMate and the Probabilistic Relational Model formalism to model and analyse data accuracy. Since the resources available for architecture analysis are usually quite scarce, the method advocates interviews as the primary data collection technique. A case study demonstrates that the method yields correct data accuracy estimates and is more resource-efficient than a competing sampling-based data accuracy estimation method.

  8. Astrophysics with Microarcsecond Accuracy Astrometry

    Unwin, Stephen C.

    2008-01-01

    Space-based astrometry promises to provide a powerful new tool for astrophysics. At a precision level of a few microarcsonds, a wide range of phenomena are opened up for study. In this paper we discuss the capabilities of the SIM Lite mission, the first space-based long-baseline optical interferometer, which will deliver parallaxes to 4 microarcsec. A companion paper in this volume will cover the development and operation of this instrument. At the level that SIM Lite will reach, better than 1 microarcsec in a single measurement, planets as small as one Earth can be detected around many dozen of the nearest stars. Not only can planet masses be definitely measured, but also the full orbital parameters determined, allowing study of system stability in multiple planet systems. This capability to survey our nearby stellar neighbors for terrestrial planets will be a unique contribution to our understanding of the local universe. SIM Lite will be able to tackle a wide range of interesting problems in stellar and Galactic astrophysics. By tracing the motions of stars in dwarf spheroidal galaxies orbiting our Milky Way, SIM Lite will probe the shape of the galactic potential history of the formation of the galaxy, and the nature of dark matter. Because it is flexibly scheduled, the instrument can dwell on faint targets, maintaining its full accuracy on objects as faint as V=19. This paper is a brief survey of the diverse problems in modern astrophysics that SIM Lite will be able to address.

  9. Tracking accuracy assessment for concentrator photovoltaic systems

    Norton, Matthew S. H.; Anstey, Ben; Bentley, Roger W.; Georghiou, George E.

    2010-10-01

    The accuracy to which a concentrator photovoltaic (CPV) system can track the sun is an important parameter that influences a number of measurements that indicate the performance efficiency of the system. This paper presents work carried out into determining the tracking accuracy of a CPV system, and illustrates the steps involved in gaining an understanding of the tracking accuracy. A Trac-Stat SL1 accuracy monitor has been used in the determination of pointing accuracy and has been integrated into the outdoor CPV module test facility at the Photovoltaic Technology Laboratories in Nicosia, Cyprus. Results from this work are provided to demonstrate how important performance indicators may be presented, and how the reliability of results is improved through the deployment of such accuracy monitors. Finally, recommendations on the use of such sensors are provided as a means to improve the interpretation of real outdoor performance.

  10. Audiovisual biofeedback improves motion prediction accuracy

    Pollock, Sean; Lee, Danny; Keall, Paul; Kim, Taeho

    2013-01-01

    Purpose: The accuracy of motion prediction, utilized to overcome the system latency of motion management radiotherapy systems, is hampered by irregularities present in the patients’ respiratory pattern. Audiovisual (AV) biofeedback has been shown to reduce respiratory irregularities. The aim of this study was to test the hypothesis that AV biofeedback improves the accuracy of motion prediction.

  11. Accuracy analysis of distributed simulation systems

    Lin, Qi; Guo, Jing

    2010-08-01

    Existed simulation works always emphasize on procedural verification, which put too much focus on the simulation models instead of simulation itself. As a result, researches on improving simulation accuracy are always limited in individual aspects. As accuracy is the key in simulation credibility assessment and fidelity study, it is important to give an all-round discussion of the accuracy of distributed simulation systems themselves. First, the major elements of distributed simulation systems are summarized, which can be used as the specific basis of definition, classification and description of accuracy of distributed simulation systems. In Part 2, the framework of accuracy of distributed simulation systems is presented in a comprehensive way, which makes it more sensible to analyze and assess the uncertainty of distributed simulation systems. The concept of accuracy of distributed simulation systems is divided into 4 other factors and analyzed respectively further more in Part 3. In Part 4, based on the formalized description of framework of accuracy analysis in distributed simulation systems, the practical approach are put forward, which can be applied to study unexpected or inaccurate simulation results. Following this, a real distributed simulation system based on HLA is taken as an example to verify the usefulness of the approach proposed. The results show that the method works well and is applicable in accuracy analysis of distributed simulation systems.

  12. Optimizing the geometrical accuracy of curvilinear meshes

    Toulorge, Thomas; Remacle, Jean-François

    2015-01-01

    This paper presents a method to generate valid high order meshes with optimized geometrical accuracy. The high order meshing procedure starts with a linear mesh, that is subsequently curved without taking care of the validity of the high order elements. An optimization procedure is then used to both untangle invalid elements and optimize the geometrical accuracy of the mesh. Standard measures of the distance between curves are considered to evaluate the geometrical accuracy in planar two-dimensional meshes, but they prove computationally too costly for optimization purposes. A fast estimate of the geometrical accuracy, based on Taylor expansions of the curves, is introduced. An unconstrained optimization procedure based on this estimate is shown to yield significant improvements in the geometrical accuracy of high order meshes, as measured by the standard Haudorff distance between the geometrical model and the mesh. Several examples illustrate the beneficial impact of this method on CFD solutions, with a part...

  13. 100% Classification Accuracy Considered Harmful: The Normalized Information Transfer Factor Explains the Accuracy Paradox

    Valverde-Albacete, Francisco J.; Carmen Peláez-Moreno

    2014-01-01

    The most widely spread measure of performance, accuracy, suffers from a paradox: predictive models with a given level of accuracy may have greater predictive power than models with higher accuracy. Despite optimizing classification error rate, high accuracy models may fail to capture crucial information transfer in the classification task. We present evidence of this behavior by means of a combinatorial analysis where every possible contingency matrix of 2, 3 and 4 classes classifiers are dep...

  14. Accuracy and consistency of modern elastomeric pumps.

    Weisman, Robyn S; Missair, Andres; Pham, Phung; Gutierrez, Juan F; Gebhard, Ralf E

    2014-01-01

    Continuous peripheral nerve blockade has become a popular method of achieving postoperative analgesia for many surgical procedures. The safety and reliability of infusion pumps are dependent on their flow rate accuracy and consistency. Knowledge of pump rate profiles can help physicians determine which infusion pump is best suited for their clinical applications and specific patient population. Several studies have investigated the accuracy of portable infusion pumps. Using methodology similar to that used by Ilfeld et al, we investigated the accuracy and consistency of several current elastomeric pumps. PMID:25140510

  15. Accuracy and Efficiency of Raytracing Photoionisation Algorithms

    Mackey, Jonathan

    2012-01-01

    Three non-equilibrium photoionisation algorithms for hydrodynamical grid-based simulation codes are compared in terms of accuracy, timestepping criteria, and parallel scaling. Explicit methods with first order time accuracy for photon conservation must use very restrictive timestep criteria to accurately track R-type ionisation fronts. A second order accurate algorithm is described which, although it requires more work per step, allows much longer timesteps and is consequently more efficient. Implicit methods allow ionisation fronts to cross many grid cells per timestep while maintaining photon conservation accuracy. It is shown, however, that errors are much larger for multi-frequency radiation then for monochromatic radiation with the implicit algorithm used here, and large errors accrue when an ionisation front crosses many optical depths in a single step. The accuracy and convergence rates of the different algorithms are tested with a large number of timestepping criteria to identify the best criterion fo...

  16. Social Security Administration Data for Enumeration Accuracy

    Social Security Administration — This dataset provides data at the national level from federal fiscal year 2006 onwards for the accuracy of the assignment of Social Security numbers (SSN) based on...

  17. Critical thinking and accuracy of nurses' diagnoses.

    Lunney, Margaret

    2003-01-01

    Interpretations of patient data are complex and diverse, contributing to a risk of low accuracy nursing diagnoses. This risk is confirmed in research findings that accuracy of nurses' diagnoses varied widely from high to low. Highly accurate diagnoses are essential, however, to guide nursing interventions for the achievement of positive health outcomes. Development of critical thinking abilities is likely to improve accuracy of nurses' diagnoses. New views of critical thinking serve as a basis for critical thinking in nursing. Seven cognitive skills and ten habits of mind are identified as dimensions of critical thinking for use in the diagnostic process. Application of the cognitive skills of critical thinking illustrates the importance of using critical thinking for accuracy of nurses' diagnoses. Ten strategies are proposed for self-development of critical thinking abilities. PMID:14649031

  18. Moyamoya disease: diagnostic accuracy of MRI

    MRI may be employed to investigate moyamoya disease, since it provides vascular information without use of contrast medium. We reported the usefulness and limitations of MR angiography (MRA) in moyamoya disease. To our knowledge, no report has appeared dealing with the diagnostic accuracy of MRI in a large number of cases of moyamoya disease, although MRI is used more commonly than MRA. We therefore undertook to evaluate the accuracy of MRI in moyamoya disease. (orig.)

  19. Coding accuracy on the psychophysical scale

    Lubomir Kostal; Petr Lansky

    2016-01-01

    Sensory neurons are often reported to adjust their coding accuracy to the stimulus statistics. The observed match is not always perfect and the maximal accuracy does not align with the most frequent stimuli. As an alternative to a physiological explanation we show that the match critically depends on the chosen stimulus measurement scale. More generally, we argue that if we measure the stimulus intensity on the scale which is proportional to the perception intensity, an improved adjustment in...

  20. Development of an artillery accuracy model

    Fann, Chee Meng.

    2006-01-01

    This thesis explains the methodologies that predict the trajectory and accuracy of an unguided, indirect-fire launched projectile in predicted fire. The trajectory is the path that a projectile travels to the impact point, while the accuracy is the measurement of the deviation of the impact point from the target. In addition, this thesis describes, the methodology for calculating the various factors such as drag and drift in the trajectory calculation. A three degree of freedom model will...

  1. Accuracy Assessment and Analysis for GPT2

    YAO Yibin

    2015-07-01

    Full Text Available GPT(global pressure and temperature is a global empirical model usually used to provide temperature and pressure for the determination of tropospheric delay, there are some weakness to GPT, these have been improved with a new empirical model named GPT2, which not only improves the accuracy of temperature and pressure, but also provides specific humidity, water vapor pressure, mapping function coefficients and other tropospheric parameters, and no accuracy analysis of GPT2 has been made until now. In this paper high-precision meteorological data from ECWMF and NOAA were used to test and analyze the accuracy of temperature, pressure and water vapor pressure expressed by GPT2, testing results show that the mean Bias of temperature is -0.59℃, average RMS is 3.82℃; absolute value of average Bias of pressure and water vapor pressure are less than 1 mb, GPT2 pressure has average RMS of 7 mb, and water vapor pressure no more than 3 mb, accuracy is different in different latitudes, all of them have obvious seasonality. In conclusion, GPT2 model has high accuracy and stability on global scale.

  2. Activity monitor accuracy in persons using canes

    Deborah Michael Wendland, PT, DPT, CPed

    2012-12-01

    Full Text Available The StepWatch activity monitor has not been validated on multiple indoor and outdoor surfaces in a population using ambulation aids. The aims of this technical report are to report on strategies to configure the StepWatch activity monitor on subjects using a cane and to report the accuracy of both leg-mounted and cane-mounted StepWatch devices on people ambulating over different surfaces while using a cane. Sixteen subjects aged 67 to 85 yr (mean 75.6 who regularly use a cane for ambulation participated. StepWatch calibration was performed by adjusting sensitivity and cadence. Following calibration optimization, accuracy was tested on both the leg-mounted and cane-mounted devices on different surfaces, including linoleum, sidewalk, grass, ramp, and stairs. The leg-mounted device had an accuracy of 93.4% across all surfaces, while the cane-mounted device had an aggregate accuracy of 84.7% across all surfaces. Accuracy of the StepWatch on the stairs was significantly less accurate (p < 0.001 when comparing surfaces using repeated measures analysis of variance. When monitoring community mobility, placement of a StepWatch on a person and his/her ambulation aid can accurately document both activity and device use.

  3. Decreased interoceptive accuracy following social exclusion.

    Durlik, Caroline; Tsakiris, Manos

    2015-04-01

    The need for social affiliation is one of the most important and fundamental human needs. Unsurprisingly, humans display strong negative reactions to social exclusion. In the present study, we investigated the effect of social exclusion on interoceptive accuracy - accuracy in detecting signals arising inside the body - measured with a heartbeat perception task. We manipulated exclusion using Cyberball, a widely used paradigm of a virtual ball-tossing game, with half of the participants being included during the game and the other half of participants being ostracized during the game. Our results indicated that heartbeat perception accuracy decreased in the excluded, but not in the included, participants. We discuss these results in the context of social and physical pain overlap, as well as in relation to internally versus externally oriented attention. PMID:25701592

  4. Coordinate metrology accuracy of systems and measurements

    Sładek, Jerzy A

    2016-01-01

    This book focuses on effective methods for assessing the accuracy of both coordinate measuring systems and coordinate measurements. It mainly reports on original research work conducted by Sladek’s team at Cracow University of Technology’s Laboratory of Coordinate Metrology. The book describes the implementation of different methods, including artificial neural networks, the Matrix Method, the Monte Carlo method and the virtual CMM (Coordinate Measuring Machine), and demonstrates how these methods can be effectively used in practice to gauge the accuracy of coordinate measurements. Moreover, the book includes an introduction to the theory of measurement uncertainty and to key techniques for assessing measurement accuracy. All methods and tools are presented in detail, using suitable mathematical formulations and illustrated with numerous examples. The book fills an important gap in the literature, providing readers with an advanced text on a topic that has been rapidly developing in recent years. The book...

  5. Observer accuracy in reading chest films

    Four board-certified radiologists have read and reread four groups of 40 chest radiographs containing nodule and infiltrate images to investigate interreader and intrareader variation. Responses were recorded using a six-point confidence level scale. Accuracy was determined from the area under the receiver operating characteristic (ROC) curve. Accuracies ranged from 0.78 to 0.98, with an average of 0.83 and a mean uncertainty of 8.2%. Intraobserver uncertainties varied from 0.5% to 16%, with a mean of 5.9%. The data were analyzed for the significance of accuracy differences using correlated ROC techniques, the kappa statistic, and the Bonnferoni criteria. Implications for using reader performance as a recertification measure are discussed

  6. Training in timing improves accuracy in golf.

    Libkuman, Terry M; Otani, Hajime; Steger, Neil

    2002-01-01

    In this experiment, the authors investigated the influence of training in timing on performance accuracy in golf. During pre- and posttesting, 40 participants hit golf balls with 4 different clubs in a golf course simulator. The dependent measure was the distance in feet that the ball ended from the target. Between the pre- and posttest, participants in the experimental condition received 10 hr of timing training with an instrument that was designed to train participants to tap their hands and feet in synchrony with target sounds. The participants in the control condition read literature about how to improve their golf swing. The results indicated that the participants in the experimental condition significantly improved their accuracy relative to the participants in the control condition, who did not show any improvement. We concluded that training in timing leads to improvement in accuracy, and that our results have implications for training in golf as well as other complex motor activities. PMID:12038497

  7. Final Technical Report: Increasing Prediction Accuracy.

    King, Bruce Hardison [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hansen, Clifford [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Stein, Joshua [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-12-01

    PV performance models are used to quantify the value of PV plants in a given location. They combine the performance characteristics of the system, the measured or predicted irradiance and weather at a site, and the system configuration and design into a prediction of the amount of energy that will be produced by a PV system. These predictions must be as accurate as possible in order for finance charges to be minimized. Higher accuracy equals lower project risk. The Increasing Prediction Accuracy project at Sandia focuses on quantifying and reducing uncertainties in PV system performance models.

  8. Systematic reviews of diagnostic test accuracy

    Leeflang, Mariska M G; Deeks, Jonathan J; Gatsonis, Constantine;

    2008-01-01

    More and more systematic reviews of diagnostic test accuracy studies are being published, but they can be methodologically challenging. In this paper, the authors present some of the recent developments in the methodology for conducting systematic reviews of diagnostic test accuracy studies....... Restrictive electronic search filters are discouraged, as is the use of summary quality scores. Methods for meta-analysis should take into account the paired nature of the estimates and their dependence on threshold. Authors of these reviews are advised to use the hierarchical summary receiver...

  9. Accuracy analysis of automatic distortion correction

    Kolecki Jakub

    2015-06-01

    Full Text Available The paper addresses the problem of the automatic distortion removal from images acquired with non-metric SLR camera equipped with prime lenses. From the photogrammetric point of view the following question arises: is the accuracy of distortion control data provided by the manufacturer for a certain lens model (not item sufficient in order to achieve demanded accuracy? In order to obtain the reliable answer to the aforementioned problem the two kinds of tests were carried out for three lens models.

  10. Field Accuracy Test of Rpas Photogrammetry

    Barry, P.; Coakley, R.

    2013-08-01

    Baseline Surveys Ltd is a company which specialises in the supply of accurate geospatial data, such as cadastral, topographic and engineering survey data to commercial and government bodies. Baseline Surveys Ltd invested in aerial drone photogrammetric technology and had a requirement to establish the spatial accuracy of the geographic data derived from our unmanned aerial vehicle (UAV) photogrammetry before marketing our new aerial mapping service. Having supplied the construction industry with survey data for over 20 years, we felt that is was crucial for our clients to clearly understand the accuracy of our photogrammetry so they can safely make informed spatial decisions, within the known accuracy limitations of our data. This information would also inform us on how and where UAV photogrammetry can be utilised. What we wanted to find out was the actual accuracy that can be reliably achieved using a UAV to collect data under field conditions throughout a 2 Ha site. We flew a UAV over the test area in a "lawnmower track" pattern with an 80% front and 80% side overlap; we placed 45 ground markers as check points and surveyed them in using network Real Time Kinematic Global Positioning System (RTK GPS). We specifically designed the ground markers to meet our accuracy needs. We established 10 separate ground markers as control points and inputted these into our photo modelling software, Agisoft PhotoScan. The remaining GPS coordinated check point data were added later in ArcMap to the completed orthomosaic and digital elevation model so we could accurately compare the UAV photogrammetry XYZ data with the RTK GPS XYZ data at highly reliable common points. The accuracy we achieved throughout the 45 check points was 95% reliably within 41 mm horizontally and 68 mm vertically and with an 11.7 mm ground sample distance taken from a flight altitude above ground level of 90 m.The area covered by one image was 70.2 m × 46.4 m, which equals 0.325 Ha. This finding has shown

  11. ACCURACY ANALYSIS OF KINECT DEPTH DATA

    K. Khoshelham

    2012-09-01

    Full Text Available This paper presents an investigation of the geometric quality of depth data obtained by the Kinect sensor. Based on the mathematical model of depth measurement by the sensor a theoretical error analysis is presented, which provides an insight into the factors influencing the accuracy of the data. Experimental results show that the random error of depth measurement increases with increasing distance to the sensor, and ranges from a few millimetres up to about 4 cm at the maximum range of the sensor. The accuracy of the data is also found to be influenced by the low resolution of the depth measurements.

  12. Speed-Accuracy Response Models: Scoring Rules Based on Response Time and Accuracy

    Maris, Gunter; van der Maas, Han

    2012-01-01

    Starting from an explicit scoring rule for time limit tasks incorporating both response time and accuracy, and a definite trade-off between speed and accuracy, a response model is derived. Since the scoring rule is interpreted as a sufficient statistic, the model belongs to the exponential family. The various marginal and conditional distributions…

  13. Accuracy of References in Five Entomology Journals.

    Kristof, Cynthia

    ln this paper, the bibliographical references in five core entomology journals are examined for citation accuracy in order to determine if the error rates are similar. Every reference printed in each journal's first issue of 1992 was examined, and these were compared to the original (cited) publications, if possible, in order to determine the…

  14. Bullet trajectory reconstruction - Methods, accuracy and precision.

    Mattijssen, Erwin J A T; Kerkhoff, Wim

    2016-05-01

    Based on the spatial relation between a primary and secondary bullet defect or on the shape and dimensions of the primary bullet defect, a bullet's trajectory prior to impact can be estimated for a shooting scene reconstruction. The accuracy and precision of the estimated trajectories will vary depending on variables such as, the applied method of reconstruction, the (true) angle of incidence, the properties of the target material and the properties of the bullet upon impact. This study focused on the accuracy and precision of estimated bullet trajectories when different variants of the probing method, ellipse method, and lead-in method are applied on bullet defects resulting from shots at various angles of incidence on drywall, MDF and sheet metal. The results show that in most situations the best performance (accuracy and precision) is seen when the probing method is applied. Only for the lowest angles of incidence the performance was better when either the ellipse or lead-in method was applied. The data provided in this paper can be used to select the appropriate method(s) for reconstruction and to correct for systematic errors (accuracy) and to provide a value of the precision, by means of a confidence interval of the specific measurement. PMID:27044032

  15. 47 CFR 65.306 - Calculation accuracy.

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false Calculation accuracy. 65.306 Section 65.306 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES (CONTINUED) INTERSTATE RATE OF RETURN PRESCRIPTION PROCEDURES AND METHODOLOGIES Exchange Carriers § 65.306 Calculation...

  16. Accuracy of sampling during mushroom cultivation

    Baars, J.J.P.; Hendrickx, P.M.; Sonnenberg, A.S.M.

    2015-01-01

    Experiments described in this report were performed to increase the accuracy of the analysis of the biological efficiency of Agaricus bisporus strains. Biological efficiency is a measure of the efficiency with which the mushroom strains use dry matter in the compost to produce mushrooms (expressed as dry matter produced).

  17. High Accuracy Transistor Compact Model Calibrations

    Hembree, Charles E. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Mar, Alan [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Robertson, Perry J. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Typically, transistors are modeled by the application of calibrated nominal and range models. These models consists of differing parameter values that describe the location and the upper and lower limits of a distribution of some transistor characteristic such as current capacity. Correspond- ingly, when using this approach, high degrees of accuracy of the transistor models are not expected since the set of models is a surrogate for a statistical description of the devices. The use of these types of models describes expected performances considering the extremes of process or transistor deviations. In contrast, circuits that have very stringent accuracy requirements require modeling techniques with higher accuracy. Since these accurate models have low error in transistor descriptions, these models can be used to describe part to part variations as well as an accurate description of a single circuit instance. Thus, models that meet these stipulations also enable the calculation of quantifi- cation of margins with respect to a functional threshold and uncertainties in these margins. Given this need, new model high accuracy calibration techniques for bipolar junction transis- tors have been developed and are described in this report.

  18. Accuracy of abdominal auscultation for bowel obstruction

    Breum, Birger Michael; Rud, Bo; Kirkegaard, Thomas; Nordentoft, Tyge

    2015-01-01

    AIM: To investigate the accuracy and inter-observer variation of bowel sound assessment in patients with clinically suspected bowel obstruction. METHODS: Bowel sounds were recorded in patients with suspected bowel obstruction using a Littmann(®) Electronic Stethoscope. The recordings were processed...

  19. The Diagnostic Accuracy of Digitized Mammography

    M. Guiti

    2008-06-01

    Full Text Available Background/Objective: Digitized mammography has several advantages over screen-film radiography in data storage and retrieval, making it a useful alternative to screen-film mammography in screening programs. The purpose of this study was to determine the diagnostic accuracy of digitized mammography in detecting breast cancer. "nPatients and Methods: 185 women (845 Images were digitized at 600 dpi. All images were reviewed by an expert radiologist. The mammograms were scored on a scale of breast imaging reporting and data system (BIRADS. The definite diagnosis was made either on the pathologic results of breast biopsy, or upon the follow-up of at least one year. The overall diagnostic accuracy of digitized mammography was calculated by the area under receiver operating characteristic curve."nResults: 242 sets of mammograms had no lesions. The total counts of masses, microcalcifications or both in one breast were 39 (11%, 42 (12%, and 25 (7%, respectively. There were 321 (92% benign and 27 (8% definite malignant lesions. The diagnostic accuracy of digitized images was 96.34% (95% CI: 94%-98%."nConclusion: The diagnostic accuracy of digitized mammography is comparably good or even better than the published results. The digitized mammography is a good substitute modality for screen-film mammography in screening programs.

  20. Observed Consultation: Confidence and Accuracy of Assessors

    Tweed, Mike; Ingham, Christopher

    2010-01-01

    Judgments made by the assessors observing consultations are widely used in the assessment of medical students. The aim of this research was to study judgment accuracy and confidence and the relationship between these. Assessors watched recordings of consultations, scoring the students on: a checklist of items; attributes of consultation; a…

  1. Accuracy in Robot Generated Image Data Sets

    Aanæs, Henrik; Dahl, Anders Bjorholm

    2015-01-01

    In this paper we present a practical innovation concerning how to achieve high accuracy of camera positioning, when using a 6 axis industrial robots to generate high quality data sets for computer vision. This innovation is based on the realization that to a very large extent the robots positioning...... in using robots for image data set generation....

  2. Direct Behavior Rating: Considerations for Rater Accuracy

    Harrison, Sayward E.; Riley-Tillman, T. Chris; Chafouleas, Sandra M.

    2014-01-01

    Direct behavior rating (DBR) offers users a flexible, feasible method for the collection of behavioral data. Previous research has supported the validity of using DBR to rate three target behaviors: academic engagement, disruptive behavior, and compliance. However, the effect of the base rate of behavior on rater accuracy has not been established.…

  3. Bayesian Methods for Medical Test Accuracy

    Lyle D. Broemeling

    2011-05-01

    Full Text Available Bayesian methods for medical test accuracy are presented, beginning with the basic measures for tests with binary scores: true positive fraction, false positive fraction, positive predictive values, and negative predictive value. The Bayesian approach is taken because of its efficient use of prior information, and the analysis is executed with a Bayesian software package WinBUGS®. The ROC (receiver operating characteristic curve gives the intrinsic accuracy of medical tests that have ordinal or continuous scores, and the Bayesian approach is illustrated with many examples from cancer and other diseases. Medical tests include X-ray, mammography, ultrasound, computed tomography, magnetic resonance imaging, nuclear medicine and tests based on biomarkers, such as blood glucose values for diabetes. The presentation continues with more specialized methods suitable for measuring the accuracies of clinical studies that have verification bias, and medical tests without a gold standard. Lastly, the review is concluded with Bayesian methods for measuring the accuracy of the combination of two or more tests.

  4. ACCURACY AND FLUENCY IN COMMUNICATIVE LANGUAGE TEACHING

    2000-01-01

    Ⅰ. Introduction In English language teaching, at whatever level, teachers feel it very important to focus on accuracy and fluency in a pedagogic way. It is now widely accepted that neither of them should be focused on alone all the way through the teaching process. From our teaching experience, we can see that to some extent this is true.

  5. Accuracy in x-ray reflectivity analysis

    Tiilikainen, J; Tilli, J-M; Bosund, V; Mattila, M; Hakkarainen, T; Sormunen, J; Lipsanen, H [Micro and Nanosciences Laboratory, Helsinki University of Technology, Micronova, PO Box 3500, FI-02015 TKK (Finland)

    2007-12-07

    The influence of Poisson noise on the accuracy of x-ray reflectivity analysis is studied with an aluminium oxide (AlO) layer on silicon. A null hypothesis which argues that other than the exact solution gives the best fitness is examined with a statistical p-value test using a significance level of {alpha} = 0.01. Simulations are performed for a fit instead of a measurement since the exact error caused by noise cannot be determined from the measurement. The p-value is studied by comparing trial curves to 1000 'measurements', each of them including synthetic Poisson noise. Confidence limits for the parameters of Parratt's formalism and the Nevot-Croce approximation are determined in (mass density, surface roughness) (thickness, surface roughness) and (thickness, mass density) planes. The most significant result is that the thickness determination accuracy of AlO is approximately {+-}0.09 nm but the accuracy is better for materials having higher mass density. It is also shown that the accuracy of mass density determination can be significantly improved using a suitably designed fitness measure. Although the power of the presented method is demonstrated only in one case, it can be used in any parameter region for a plethora of single layer systems to find the lower limit of the error made in x-ray reflectivity analysis.

  6. Accuracy in x-ray reflectivity analysis

    The influence of Poisson noise on the accuracy of x-ray reflectivity analysis is studied with an aluminium oxide (AlO) layer on silicon. A null hypothesis which argues that other than the exact solution gives the best fitness is examined with a statistical p-value test using a significance level of α = 0.01. Simulations are performed for a fit instead of a measurement since the exact error caused by noise cannot be determined from the measurement. The p-value is studied by comparing trial curves to 1000 'measurements', each of them including synthetic Poisson noise. Confidence limits for the parameters of Parratt's formalism and the Nevot-Croce approximation are determined in (mass density, surface roughness) (thickness, surface roughness) and (thickness, mass density) planes. The most significant result is that the thickness determination accuracy of AlO is approximately ±0.09 nm but the accuracy is better for materials having higher mass density. It is also shown that the accuracy of mass density determination can be significantly improved using a suitably designed fitness measure. Although the power of the presented method is demonstrated only in one case, it can be used in any parameter region for a plethora of single layer systems to find the lower limit of the error made in x-ray reflectivity analysis

  7. The impact of accuracy motivation on interpretation, comparison, and correction processes: accuracy x knowledge accessibility effects.

    Stapel, D A; Koomen, W; Zeelenberg, M

    1998-04-01

    Four studies provide evidence for the notion that there may be boundaries to the extent to which accuracy motivation may help perceivers to escape the influence of fortuitously activated information. Specifically, although accuracy motivations may eliminate assimilative accessibility effects, they are less likely to eliminate contrastive accessibility effects. It was found that the occurrence of different types of contrast effects (comparison and correction) was not significantly affected by participants' accuracy motivations. Furthermore, it was found that the mechanisms instigated by accuracy motivations differ from those ignited by correction instructions: Accuracy motivations attenuate assimilation effects because perceivers add target interpretations to the one suggested by primed information. Conversely, it was found that correction instructions yield contrast and prompt respondents to remove the priming event's influence from their reaction to the target. PMID:9569650

  8. High accuracy FIONA-AFM hybrid imaging

    Multi-protein complexes are ubiquitous and play essential roles in many biological mechanisms. Single molecule imaging techniques such as electron microscopy (EM) and atomic force microscopy (AFM) are powerful methods for characterizing the structural properties of multi-protein and multi-protein-DNA complexes. However, a significant limitation to these techniques is the ability to distinguish different proteins from one another. Here, we combine high resolution fluorescence microscopy and AFM (FIONA-AFM) to allow the identification of different proteins in such complexes. Using quantum dots as fiducial markers in addition to fluorescently labeled proteins, we are able to align fluorescence and AFM information to ≥8 nm accuracy. This accuracy is sufficient to identify individual fluorescently labeled proteins in most multi-protein complexes. We investigate the limitations of localization precision and accuracy in fluorescence and AFM images separately and their effects on the overall registration accuracy of FIONA-AFM hybrid images. This combination of the two orthogonal techniques (FIONA and AFM) opens a wide spectrum of possible applications to the study of protein interactions, because AFM can yield high resolution (5-10 nm) information about the conformational properties of multi-protein complexes and the fluorescence can indicate spatial relationships of the proteins in the complexes. -- Research highlights: → Integration of fluorescent signals in AFM topography with high (<10 nm) accuracy. → Investigation of limitations and quantitative analysis of fluorescence-AFM image registration using quantum dots. → Fluorescence center tracking and display as localization probability distributions in AFM topography (FIONA-AFM). → Application of FIONA-AFM to a biological sample containing damaged DNA and the DNA repair proteins UvrA and UvrB conjugated to quantum dots.

  9. Diagnostic accuracy of MRCP in choledocholithiasis

    Purpose: To evaluate the accuracy of MRCP in diagnosing choledocholithiasis considering Endoscopic Retrograde Cholangiopancreatography (ERCP) as the gold standard. To compare the results achieved during the first two years of use (1999-2000) of Magnetic Resonance Cholangiopancreatography (MRCP) in patients with suspected choledocholithiasis with those achieved during the following two years (2001-2002) in order to establish the repeatability and objectivity of MRCP results. Materials and methods: One hundred and seventy consecutive patients underwent MRCP followed by ERCP within 72 h. In 22/170 (13%) patients ERCP was unsuccessful for different reasons. MRCP was performed using a 1.5 T magnet with both multi-slice HASTE sequences and thick-slice projection technique. Choledocholithiasis was diagnosed in the presence of signal void images in the dependent portion of the duct surrounded by hyperintense bile and detected at least in two projections. The MRCP results, read independently from the ERCP results, were compared in two different and subsequent periods. Results: ERCP confirmed choledocholithiasis in 87 patients. In these cases the results of MRCP were the following: 78 true positives, 53 true negatives, 7 false positives, and 9 false negatives. The sensitivity, specificity and accuracy were 90%, 88% and 89%, respectively. After the exclusion of stones with diameters smaller than 6 mm, the sensitivity, specificity and accuracy were 100%, 99% and 99%, respectively. MRCP accuracy was related to the size of the stones. There was no significant statistical difference between the results obtained in the first two-year period and those obtained in the second period. Conclusions: MRCP i sufficiently accurate to replace ERCP in patients with suspected choledocholithiasis. The results are related to the size of stones. The use of well-defined radiological signs allows good diagnostic accuracy independent of the learning curve

  10. Positional Accuracy Assessment of Googleearth in Riyadh

    Farah, Ashraf; Algarni, Dafer

    2014-06-01

    Google Earth is a virtual globe, map and geographical information program that is controlled by Google corporation. It maps the Earth by the superimposition of images obtained from satellite imagery, aerial photography and GIS 3D globe. With millions of users all around the globe, GoogleEarth® has become the ultimate source of spatial data and information for private and public decision-support systems besides many types and forms of social interactions. Many users mostly in developing countries are also using it for surveying applications, the matter that raises questions about the positional accuracy of the Google Earth program. This research presents a small-scale assessment study of the positional accuracy of GoogleEarth® Imagery in Riyadh; capital of Kingdom of Saudi Arabia (KSA). The results show that the RMSE of the GoogleEarth imagery is 2.18 m and 1.51 m for the horizontal and height coordinates respectively.

  11. Improving the accuracy of dynamic mass calculation

    Oleksandr F. Dashchenko

    2015-06-01

    Full Text Available With the acceleration of goods transporting, cargo accounting plays an important role in today's global and complex environment. Weight is the most reliable indicator of the materials control. Unlike many other variables that can be measured indirectly, the weight can be measured directly and accurately. Using strain-gauge transducers, weight value can be obtained within a few milliseconds; such values correspond to the momentary load, which acts on the sensor. Determination of the weight of moving transport is only possible by appropriate processing of the sensor signal. The aim of the research is to develop a methodology for weighing freight rolling stock, which increases the accuracy of the measurement of dynamic mass, in particular wagon that moves. Apart from time-series methods, preliminary filtration for improving the accuracy of calculation is used. The results of the simulation are presented.

  12. Improvement in Rayleigh Scattering Measurement Accuracy

    Fagan, Amy F.; Clem, Michelle M.; Elam, Kristie A.

    2012-01-01

    Spectroscopic Rayleigh scattering is an established flow diagnostic that has the ability to provide simultaneous velocity, density, and temperature measurements. The Fabry-Perot interferometer or etalon is a commonly employed instrument for resolving the spectrum of molecular Rayleigh scattered light for the purpose of evaluating these flow properties. This paper investigates the use of an acousto-optic frequency shifting device to improve measurement accuracy in Rayleigh scattering experiments at the NASA Glenn Research Center. The frequency shifting device is used as a means of shifting the incident or reference laser frequency by 1100 MHz to avoid overlap of the Rayleigh and reference signal peaks in the interference pattern used to obtain the velocity, density, and temperature measurements, and also to calibrate the free spectral range of the Fabry-Perot etalon. The measurement accuracy improvement is evaluated by comparison of Rayleigh scattering measurements acquired with and without shifting of the reference signal frequency in a 10 mm diameter subsonic nozzle flow.

  13. Evaluating measurement accuracy a practical approach

    Rabinovich, Semyon G

    2013-01-01

    The goal of Evaluating Measurement Accuracy: A Practical Approach is to present methods for estimating the accuracy of measurements performed in industry, trade, and scientific research. From developing the theory of indirect measurements to proposing new methods of reduction, transformation, and enumeration, this work encompasses the full range of measurement data processing. It includes many examples that illustrate the application of general theory to typical problems encountered in measurement practice. As a result, the book serves as an inclusive reference work for data processing of all types of measurements: single and multiple, combined and simultaneous, direct (both linear and nonlinear), and indirect (both dependent and independent). It is a working tool for experimental scientists and engineers of all disciplines who work with instrumentation. It is also a good resource for natural science and engineering students and for technicians performing measurements in industry. A key feature of the book is...

  14. FNAC ACCURACY IN DIAGNOSIS OF BREAST LESIONS

    Venugopal; Pratap; Nikshita

    2014-01-01

    BACKGROUND: Malignancy of breast imposes significant reduction in life span. The prognosis of breast cancer is primarily dependent on the extent of disease and also early diagnosis in important. FNAC is a widely accepted cytological technique in the early diagnosis of palpable breast lesions. There have been many studies of accuracy of FNAC, which has been shown to be high in many centres. AIMS: To compare cytological and histopathological diagnosis of breast lesions and to ...

  15. Marginal accuracy of temporary composite crowns.

    Tjan, A H; Tjan, A H; Grant, B E

    1987-10-01

    An in vitro study was conducted to quantitatively compare the marginal adaptation of temporary crowns made from Protemp material with those made from Scutan, Provisional, and Trim materials. A direct technique was used to make temporary restorations on prepared teeth with an impression as a matrix. Protem, Trim, and Provisional materials produced temporary crowns of comparable accuracy. Crowns made from Scutan material had open margins. PMID:2959770

  16. On the accuracy of language trees.

    Simone Pompei

    Full Text Available Historical linguistics aims at inferring the most likely language phylogenetic tree starting from information concerning the evolutionary relatedness of languages. The available information are typically lists of homologous (lexical, phonological, syntactic features or characters for many different languages: a set of parallel corpora whose compilation represents a paramount achievement in linguistics. From this perspective the reconstruction of language trees is an example of inverse problems: starting from present, incomplete and often noisy, information, one aims at inferring the most likely past evolutionary history. A fundamental issue in inverse problems is the evaluation of the inference made. A standard way of dealing with this question is to generate data with artificial models in order to have full access to the evolutionary process one is going to infer. This procedure presents an intrinsic limitation: when dealing with real data sets, one typically does not know which model of evolution is the most suitable for them. A possible way out is to compare algorithmic inference with expert classifications. This is the point of view we take here by conducting a thorough survey of the accuracy of reconstruction methods as compared with the Ethnologue expert classifications. We focus in particular on state-of-the-art distance-based methods for phylogeny reconstruction using worldwide linguistic databases. In order to assess the accuracy of the inferred trees we introduce and characterize two generalizations of standard definitions of distances between trees. Based on these scores we quantify the relative performances of the distance-based algorithms considered. Further we quantify how the completeness and the coverage of the available databases affect the accuracy of the reconstruction. Finally we draw some conclusions about where the accuracy of the reconstructions in historical linguistics stands and about the leading directions to improve

  17. Do Investors Learn About Analyst Accuracy?

    Chang, Charles; Daouk, Hazem; Wang, Albert

    2008-01-01

    We study the impact of analyst forecasts on prices to determine whether investors learn about analyst accuracy. Our test market is the crude oil futures market. Prices rise when analysts forecast a decrease (increase) in crude supplies. In the 15 minutes following supply realizations, prices rise (fall) when forecasts have been too high (low). In both the initial price action relative to forecasts and in the subsequent reaction relative to realized forecast errors, the price response is stron...

  18. Earnings Forecast Accuracy And Career Concerns

    Roger, Tristan

    2015-01-01

    Previous studies show that analysts' compensation is not linked to earnings forecast accuracy. We evidence however that analysts have incentives to issue accurate forecasts. We show that brokerage houses reward their best forecasters by assigning them to large, mature firms. Covering such firms increases the potential for future compensation as these firms generate a great deal of investment banking and trading activities. The coverage of such firms also increases analysts' exposure to large ...

  19. The accuracy of portable peak flow meters.

    Miller, M. R.; Dickinson, S A; Hitchings, D J

    1992-01-01

    BACKGROUND: The variability of peak expiratory flow (PEF) is now commonly used in the diagnosis and management of asthma. It is essential for PEF meters to have a linear response in order to obtain an unbiased measurement of PEF variability. As the accuracy and linearity of portable PEF meters have not been rigorously tested in recent years this aspect of their performance has been investigated. METHODS: The response of several portable PEF meters was tested with absolute standards of flow ge...

  20. Limiting Accuracy of Inexact Saddle Point Solvers

    Rozložník, Miroslav; Jiránek, Pavel

    Dundee : University of Dundee, 2007 - (Griffith, D.; Watson , G.). s. 33-33 [Biennial Conference on Numerical Analysis /22./. 26.06.2007-29.06.2007, University of Dundee] R&D Projects: GA MŠk 1M0554; GA AV ČR 1ET400300415 Institutional research plan: CEZ:AV0Z10300504 Keywords : saddle point systems * iterative methods * rounding error analysis * limiting accuracy

  1. Accuracy of radiocarbon analyses at ANTARES

    Lawson, E.M.; Fink, D.; Hotchkis, M.; Hua, Q.; Jacobsen, G.; Smith, A.M.; Tuniz, C. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1996-12-31

    Accuracy in Accelerator Mass Spectroscopy (AMS) measurements, as distinct from precision, requires the application of a number of corrections. Most of these are well known except in extreme circumstances and AMS can deliver radiocarbon results which are both precise and accurate in the 0.5 to 1.0% range. The corrections involved in obtaining final radiocarbon ages are discussed. 3 refs., 1 tab.

  2. FIELD ACCURACY TEST OF RPAS PHOTOGRAMMETRY

    Barry, P; Coakley, R.

    2013-01-01

    Baseline Surveys Ltd is a company which specialises in the supply of accurate geospatial data, such as cadastral, topographic and engineering survey data to commercial and government bodies. Baseline Surveys Ltd invested in aerial drone photogrammetric technology and had a requirement to establish the spatial accuracy of the geographic data derived from our unmanned aerial vehicle (UAV) photogrammetry before marketing our new aerial mapping service. Having supplied the construction i...

  3. Credit report accuracy and access to credit

    Avery, Robert B.; Paul S. Calem; Glenn B. Canner

    2004-01-01

    Data that credit-reporting agencies maintain on consumers' credit-related experiences play a central role in U.S. credit markets. Analysts widely agree that the data enable these markets to function more efficiently and at lower cost than would otherwise be possible. Despite the great benefits of the current system, however, some analysts have raised concerns about the accuracy, timeliness, completeness, and consistency of consumer credit records and about the effects of data problems on the ...

  4. Radioactivity analysis of food and accuracy control

    From the fact that radioactive substances have been detected from the foods such as agricultural and livestock products and marine products due to the accident of the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company, the Ministry of Health, Labour and Welfare stipulated new standards geared to general foods on radioactive cesium by replacing the interim standards up to now. Various institutions began to measure radioactivity on the basis of this instruction, but as a new challenge, a problem of the reliability of the data occurred. Therefore, accuracy control to indicate the proof that the quality of the data can be retained at an appropriate level judging from an objective manner is important. In order to consecutively implement quality management activities, it is necessary for each inspection agency to build an accuracy control system. This paper introduces support service, as a new attempt, for establishing the accuracy control system. This service is offered jointly by three organizations, such as TUV Rheinland Japan Ltd., Japan Frozen Foods Inspection Corporation, and Japan Chemical Analysis Center. This service consists of the training of radioactivity measurement practitioners, proficiency test for radioactive substance measurement, and personal authentication. (O.A.)

  5. Accuracy of stereolithographic models of human anatomy

    A study was undertaken to determine the dimensional accuracy of anatomical replicas derived from X-ray 3D computed tomography (CT) images and produced using the rapid prototyping technique of stereolithography (SLA). A dry bone skull and geometric phantom were scanned, and replicas were produced. Distance measurements were obtained to compare the original objects and the resulting replicas. Repeated measurements between anatomical landmarks were used for comparison of the original skull and replica. Results for the geometric phantom demonstrate a mean difference of +0.47mm, representing an accuracy of 97.7-99.12%. Measurements of the skull produced a range of absolute differences (maximum +4.62mm, minimum +0.1mm, mean +0.85mm). These results support the use of SLA models of human anatomical structures in such areas as pre-operative planning of complex surgical procedures. For applications where higher accuracy is required, improvements can be expected by utilizing smaller pixel resolution in the CT images. Stereolithographic models can now be confidently employed as accurate, three-dimensional replicas of complex, anatomical structures. 14 refs., 2 tabs., 8 figs

  6. Algorithms for improving accuracy of spray simulation

    ZHANG HuiYa; ZHANG YuSheng; XIAO HeLin; XU Bo

    2007-01-01

    Fuel spray is the pivotal process of direct injection engine combustion. The accuracy of spray simulation determines the reliability of combustion calculation. However, the traditional techniques of spray simulation in KIVA and commercial CFD codes are very susceptible to grid resolution. As a consequence, predicted engine performance and emission can depend on the computational mesh. The two main causes of this problem are the droplet collision algorithm and coupling between gas and liquid phases. In order to improve the accuracy of spray simulation, the original KIVA code is modified using the cross mesh droplet collision (CMC) algorithm and gas phase velocity interpolation algorithm. In the constant volume apparatus and D.I. Diesel engine, the improvements of the modified KIVA code in spray simulation accuracy are checked from spray structure, predicted average drop size and spray tip penetration, respectively. The results show a dramatic decrease in grid dependency. With these changes, the distorted phenomenon of spray structure is vanished. The uncertainty in predicted average drop size is reduced from 30 to 5 μm in constant volume apparatus calculation, and the uncertainty is further reduced to 2 μm in an engine simulation. The predicted spray tip penetrations in engine simulation also have better consistency in medium and fine meshes.

  7. 100% classification accuracy considered harmful: the normalized information transfer factor explains the accuracy paradox.

    Francisco J Valverde-Albacete

    Full Text Available The most widely spread measure of performance, accuracy, suffers from a paradox: predictive models with a given level of accuracy may have greater predictive power than models with higher accuracy. Despite optimizing classification error rate, high accuracy models may fail to capture crucial information transfer in the classification task. We present evidence of this behavior by means of a combinatorial analysis where every possible contingency matrix of 2, 3 and 4 classes classifiers are depicted on the entropy triangle, a more reliable information-theoretic tool for classification assessment. Motivated by this, we develop from first principles a measure of classification performance that takes into consideration the information learned by classifiers. We are then able to obtain the entropy-modulated accuracy (EMA, a pessimistic estimate of the expected accuracy with the influence of the input distribution factored out, and the normalized information transfer factor (NIT, a measure of how efficient is the transmission of information from the input to the output set of classes. The EMA is a more natural measure of classification performance than accuracy when the heuristic to maximize is the transfer of information through the classifier instead of classification error count. The NIT factor measures the effectiveness of the learning process in classifiers and also makes it harder for them to "cheat" using techniques like specialization, while also promoting the interpretability of results. Their use is demonstrated in a mind reading task competition that aims at decoding the identity of a video stimulus based on magnetoencephalography recordings. We show how the EMA and the NIT factor reject rankings based in accuracy, choosing more meaningful and interpretable classifiers.

  8. 100% classification accuracy considered harmful: the normalized information transfer factor explains the accuracy paradox.

    Valverde-Albacete, Francisco J; Peláez-Moreno, Carmen

    2014-01-01

    The most widely spread measure of performance, accuracy, suffers from a paradox: predictive models with a given level of accuracy may have greater predictive power than models with higher accuracy. Despite optimizing classification error rate, high accuracy models may fail to capture crucial information transfer in the classification task. We present evidence of this behavior by means of a combinatorial analysis where every possible contingency matrix of 2, 3 and 4 classes classifiers are depicted on the entropy triangle, a more reliable information-theoretic tool for classification assessment. Motivated by this, we develop from first principles a measure of classification performance that takes into consideration the information learned by classifiers. We are then able to obtain the entropy-modulated accuracy (EMA), a pessimistic estimate of the expected accuracy with the influence of the input distribution factored out, and the normalized information transfer factor (NIT), a measure of how efficient is the transmission of information from the input to the output set of classes. The EMA is a more natural measure of classification performance than accuracy when the heuristic to maximize is the transfer of information through the classifier instead of classification error count. The NIT factor measures the effectiveness of the learning process in classifiers and also makes it harder for them to "cheat" using techniques like specialization, while also promoting the interpretability of results. Their use is demonstrated in a mind reading task competition that aims at decoding the identity of a video stimulus based on magnetoencephalography recordings. We show how the EMA and the NIT factor reject rankings based in accuracy, choosing more meaningful and interpretable classifiers. PMID:24427282

  9. [True color accuracy in digital forensic photography].

    Ramsthaler, Frank; Birngruber, Christoph G; Kröll, Ann-Katrin; Kettner, Mattias; Verhoff, Marcel A

    2016-01-01

    Forensic photographs not only need to be unaltered and authentic and capture context-relevant images, along with certain minimum requirements for image sharpness and information density, but color accuracy also plays an important role, for instance, in the assessment of injuries or taphonomic stages, or in the identification and evaluation of traces from photos. The perception of color not only varies subjectively from person to person, but as a discrete property of an image, color in digital photos is also to a considerable extent influenced by technical factors such as lighting, acquisition settings, camera, and output medium (print, monitor). For these reasons, consistent color accuracy has so far been limited in digital photography. Because images usually contain a wealth of color information, especially for complex or composite colors or shades of color, and the wavelength-dependent sensitivity to factors such as light and shadow may vary between cameras, the usefulness of issuing general recommendations for camera capture settings is limited. Our results indicate that true image colors can best and most realistically be captured with the SpyderCheckr technical calibration tool for digital cameras tested in this study. Apart from aspects such as the simplicity and quickness of the calibration procedure, a further advantage of the tool is that the results are independent of the camera used and can also be used for the color management of output devices such as monitors and printers. The SpyderCheckr color-code patches allow true colors to be captured more realistically than with a manual white balance tool or an automatic flash. We therefore recommend that the use of a color management tool should be considered for the acquisition of all images that demand high true color accuracy (in particular in the setting of injury documentation). PMID:27386623

  10. Accuracy of velocities from repeated GPS measurements

    Akarsu, V.; Sanli, D. U.; Arslan, E.

    2015-04-01

    Today repeated GPS measurements are still in use, because we cannot always employ GPS permanent stations due to a variety of limitations. One area of study that uses velocities/deformation rates from repeated GPS measurements is the monitoring of crustal motion. This paper discusses the quality of the velocities derived using repeated GPS measurements for the aim of monitoring crustal motion. From a global network of International GNSS Service (IGS) stations, we processed GPS measurements repeated monthly and annually spanning nearly 15 years and estimated GPS velocities for GPS baseline components latitude, longitude and ellipsoidal height. We used web-based GIPSY for the processing. Assuming true deformation rates can only be determined from the solutions of 24 h observation sessions, we evaluated the accuracy of the deformation rates from 8 and 12 h sessions. We used statistical hypothesis testing to assess the velocities derived from short observation sessions. In addition, as an alternative control method we checked the accuracy of GPS solutions from short observation sessions against those of 24 h sessions referring to statistical criteria that measure the accuracy of regression models. Results indicate that the velocities of the vertical component are completely affected when repeated GPS measurements are used. The results also reveal that only about 30% of the 8 h solutions and about 40% of 12 h solutions for the horizontal coordinates are acceptable for velocity estimation. The situation is much worse for the vertical component in which none of the solutions from campaign measurements are acceptable for obtaining reliable deformation rates.

  11. Improvement of focus accuracy on processed wafer

    Higashibata, Satomi; Komine, Nobuhiro; Fukuhara, Kazuya; Koike, Takashi; Kato, Yoshimitsu; Hashimoto, Kohji

    2013-04-01

    As feature size shrinkage in semiconductor device progress, process fluctuation, especially focus strongly affects device performance. Because focus control is an ongoing challenge in optical lithography, various studies have sought for improving focus monitoring and control. Focus errors are due to wafers, exposure tools, reticles, QCs, and so on. Few studies are performed to minimize the measurement errors of auto focus (AF) sensors of exposure tool, especially when processed wafers are exposed. With current focus measurement techniques, the phase shift grating (PSG) focus monitor 1) has been already proposed and its basic principle is that the intensity of the diffraction light of the mask pattern is made asymmetric by arranging a π/2 phase shift area on a reticle. The resist pattern exposed at the defocus position is shifted on the wafer and shifted pattern can be easily measured using an overlay inspection tool. However, it is difficult to measure shifted pattern for the pattern on the processed wafer because of interruptions caused by other patterns in the underlayer. In this paper, we therefore propose "SEM-PSG" technique, where the shift of the PSG resist mark is measured by employing critical dimension-scanning electron microscope (CD-SEM) to measure the focus error on the processed wafer. First, we evaluate the accuracy of SEM-PSG technique. Second, by applying the SEM-PSG technique and feeding the results back to the exposure, we evaluate the focus accuracy on processed wafers. By applying SEM-PSG feedback, the focus accuracy on the processed wafer was improved from 40 to 29 nm in 3σ.

  12. Accuracy of the river discharge measurement

    Chung Yang, Han

    2013-04-01

    Discharge values recorded for water conservancy and hydrological analysis is a very important work. Flood control projects, watershed remediation and river environmental planning projects quite need the discharge measurement data. In Taiwan, we have 129 rivers, in accordance with the watershed situation, economic development and other factors, divided into 24 major rivers, 29 minor rivers and 79 ordinary rivers. If each river needs to measure and record these discharge values, it will be enormous work. In addition, the characteristics of Taiwan's rivers contain steep slope, flow rapidly and sediment concentration higher, so it really encounters some difficulties in high flow measurement. When the flood hazards come, to seek a solution for reducing the time, manpower and material resources in river discharge measurement is very important. In this study, the river discharge measurement accuracy is used to determine the tolerance percentage to reduce the number of vertical velocity measurements, thereby reducing the time, manpower and material resources in the river discharge measurement. The velocity data sources used in this study form Yang (1998). Yang (1998) used the Fiber-optic Laser Doppler Velocimetery (FLDV) to obtain different velocity data under different experimental conditions. In this study, we use these data to calculate the mean velocity of each vertical line by three different velocity profile formula (that is, the law of the wall, Chiu's theory, Hu's theory), and then multiplied by each sub-area to obtain the discharge measurement values and compared with the true values (obtained by the direct integration mode) to obtain the accuracy of discharge. The research results show that the discharge measurement values obtained by Chiu's theory are closer to the true value, while the maximum error is the law of the wall. The main reason is that the law of the wall can't describe the maximum velocity occurred in underwater. In addition, the results also show

  13. Accuracy of Ultrasonography in Diagnosing Acute Appendicitis

    Parisa Javidi Parsijani; Nima Pourhabibi Zarandi; Shahram Paydar; Hamidreza Abbasi; Shahram Bolandparvaz

    2013-01-01

    Objectives: To evaluate the accuracy of sonography in diagnosing acute appendicitis in patients with Alvarado score 4–7.Methods: This is a retrospective cross-sectional study being performed in Namazee hospital affiliated with Shiraz University of Medical sciences during a one year period from 9/2007 to 9/2008. We evaluated all patients with Alvarado score 4-7 and divided them in two groups: those with Ultrasound study prior to surgery and those without any imaging modalities for diagnosis of...

  14. Proper motion accuracy of WFPDF stars

    Chapanov, Y.; Vondrák, Jan; Ron, Cyril; Štefka, Vojtěch

    Beograd : Astronomical Society "Rudjer Boškovič", 2012 - (Tsvetkov, M.; Dimitrijevič, M.; Tsvetkova, K.; Kounchev, O.; Mijajlovič, Ž.), s. 169-176 ISBN 9788689035018. [Bulgarian-Serbian Astronomical Conference /7./. Chepelare (BG), 01.06.2010-04.06.2010] R&D Projects: GA MŠk(CZ) LC506 Institutional research plan: CEZ:AV0Z10030501 Keywords : proper motions * accuracy Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics http://wfpdb.org/ftp/7_BSAC/pdfs/c06.pdf

  15. On the Accuracy of IGS Orbits

    Griffiths, J.; Ray, J.

    2007-12-01

    In order to explore the reliability of IGS internal orbit accuracy estimates, we have compared the geocentric satellite positions at the midnight epoch between consecutive days for the period since November 5, 2006, when the IGS changed its method of antenna calibration. For each pair of orbits, day "A" has been fitted to the extended CODE orbit model (three position and three velocity parameters plus nine nuisance solar radiation parameters), using the IGS05 Final orbits as psuedo-observations, and extrapolated to epoch 24:00 to compare with the 00:00 epoch from the IGS05 Final orbits of day "B". This yields a time series of orbit repeatability measures, analogous to the classical geodetic test for position determinations. To assess the error introduced by the fitting and extrapolation process, the same procedure has been applied to several days dropping the 23:45 epoch, fitting up to 23:30, extrapolating to 23:45, and comparing with reported positions for 23:45. The test differences range between 0 and 10 mm (mean = 3 mm) per geocentric component with 3D differences of 3 to 10 mm (mean = 6 mm). So, the effect of the orbit fitting-extrapolation process nearly always adds insignificant noise to the day- boundary orbit comparisons. If we compare our average 1D position differences to the official IGS accuracy codes (derived from the internal agreement among combined orbit solutions), root-sum-squared for each pair of days, the actual discontinuities are not well correlated with the expected performance values. If instead the IGS RMS values from the Final combination long-arc analyses (which also use the extended CODE model) are taken as the measure of IGS accuracy, the actual orbit discontinuties are much better represented. This is despite the fact that our day- boundary offsets apply to a single epoch each day and the long-arc analyses consider variations over a day (compared to the satellite dynamics determined over the full week). Our method is not well suited

  16. Computing High Accuracy Power Spectra with Pico

    Fendt, William A.; Wandelt, Benjamin D.

    2007-01-01

    This paper presents the second release of Pico (Parameters for the Impatient COsmologist). Pico is a general purpose machine learning code which we have applied to computing the CMB power spectra and the WMAP likelihood. For this release, we have made improvements to the algorithm as well as the data sets used to train Pico, leading to a significant improvement in accuracy. For the 9 parameter nonflat case presented here Pico can on average compute the TT, TE and EE spectra to better than 1% ...

  17. Controlling the accuracy of chemical analysis

    Most of the IAEA reference materials are certified in intercomparisons by calculation of the overall mean of reported laboratory mean values. IAEA certification is provided at ''A level'' (satisfactory, or high degree of confidence), or at ''B level'' (acceptable, or reasonable degree of confidence) sampling , storage and preliminary processing, use of reliable analytical methods, internal and external control of accuracy and reliability result in excellent certified reference materials for inorganic, geologic, environmental, biological and other quantitative analysis by means of conventional and nuclear methods. 34 refs, 4 figs, 3 tabs

  18. High precision numerical accuracy in physics research

    Concerns arise that the current standard of double-precision floating-point may no longer be sufficient for today's large-scale numerical simulations. One approach to solve this problem will be to switch to a wider floating-point format: the upcoming quadruple-precision standard is introduced and compared to currently available software-based approaches. Another complimentary approach is to use mathematical and algorithmic techniques to improve the accuracy of large floating-point programs and the confidence in the quality of the result

  19. Dust trajectory sensor: accuracy and data analysis.

    Xie, J; Sternovsky, Z; Grün, E; Auer, S; Duncan, N; Drake, K; Le, H; Horanyi, M; Srama, R

    2011-10-01

    The Dust Trajectory Sensor (DTS) instrument is developed for the measurement of the velocity vector of cosmic dust particles. The trajectory information is imperative in determining the particles' origin and distinguishing dust particles from different sources. The velocity vector also reveals information on the history of interaction between the charged dust particle and the magnetospheric or interplanetary space environment. The DTS operational principle is based on measuring the induced charge from the dust on an array of wire electrodes. In recent work, the DTS geometry has been optimized [S. Auer, E. Grün, S. Kempf, R. Srama, A. Srowig, Z. Sternovsky, and V Tschernjawski, Rev. Sci. Instrum. 79, 084501 (2008)] and a method of triggering was developed [S. Auer, G. Lawrence, E. Grün, H. Henkel, S. Kempf, R. Srama, and Z. Sternovsky, Nucl. Instrum. Methods Phys. Res. A 622, 74 (2010)]. This article presents the method of analyzing the DTS data and results from a parametric study on the accuracy of the measurements. A laboratory version of the DTS has been constructed and tested with particles in the velocity range of 2-5 km/s using the Heidelberg dust accelerator facility. Both the numerical study and the analyzed experimental data show that the accuracy of the DTS instrument is better than about 1% in velocity and 1° in direction. PMID:22047326

  20. Improvements on the accuracy of beam bugs

    At LLNL resistive wall monitors are used to measure the current and position used on ETA-II show a droop in signal due to a fast redistribution time constant of the signals. This paper presents the analysis and experimental test of the beam bugs used for beam current and position measurements in and after the fast kicker. It concludes with an outline of present and future changes that can be made to improve the accuracy of these beam bugs. of intense electron beams in electron induction linacs and beam transport lines. These, known locally as ''beam bugs'', have been used throughout linear induction accelerators as essential diagnostics of beam current and location. Recently, the development of a fast beam kicker has required improvement in the accuracy of measuring the position of beams. By picking off signals at more than the usual four positions around the monitor, beam position measurement error can be greatly reduced. A second significant source of error is the mechanical variation of the resistor around the bug

  1. Improvements on the accuracy of beam bugs

    At LLNL resistive wall monitors are used to measure the current and position used on ETA-II show a droop in signal due to a fast redistribution time constant of the signals. This paper presents the analysis and experimental test of the beam bugs used for beam current and position measurements in and after the fast kicker. It concludes with an outline of present and future changes that can be made to improve the accuracy of these beam bugs. of intense electron beams in electron induction linacs and beam transport lines. These, known locally as beam bugs, have been used throughout linear induction accelerators as essential diagnostics of beam current and location. Recently, the development of a fast beam kicker has required improvement in the accuracy of measuring the position of beams. By picking off signals at more than the usual four positions around the monitor, beam position measurement error can be greatly reduced. A second significant source of error is the mechanical variation of the resistor around the bug

  2. Fast and High Accuracy Wire Scanner

    Koujili, M; Koopman, J; Ramos, D; Sapinski, M; De Freitas, J; Ait Amira, Y; Djerdir, A

    2009-01-01

    Scanning of a high intensity particle beam imposes challenging requirements on a Wire Scanner system. It is expected to reach a scanning speed of 20 m.s-1 with a position accuracy of the order of 1 μm. In addition a timing accuracy better than 1 millisecond is needed. The adopted solution consists of a fork holding a wire rotating by a maximum of 200°. Fork, rotor and angular position sensor are mounted on the same axis and located in a chamber connected to the beam vacuum. The requirements imply the design of a system with extremely low vibration, vacuum compatibility, radiation and temperature tolerance. The adopted solution consists of a rotary brushless synchronous motor with the permanent magnet rotor installed inside of the vacuum chamber and the stator installed outside. The accurate position sensor will be mounted on the rotary shaft inside of the vacuum chamber, has to resist a bake-out temperature of 200°C and ionizing radiation up to a dozen of kGy/year. A digital feedback controller allows maxi...

  3. Accuracy of the blood pressure measurement.

    Rabbia, F; Del Colle, S; Testa, E; Naso, D; Veglio, F

    2006-08-01

    Blood pressure measurement is the cornerstone for the diagnosis, the treatment and the research on arterial hypertension, and all of the decisions about one of these single aspects may be dramatically influenced by the accuracy of the measurement. Over the past 20 years or so, the accuracy of the conventional Riva-Rocci/Korotkoff technique of blood pressure measurement has been questioned and efforts have been made to improve the technique with automated devices. In the same period, recognition of the phenomenon of white coat hypertension, whereby some individuals with an apparent increase in blood pressure have normal, or reduced, blood pressures when measurement is repeated away from the medical environment, has focused attention on methods of measurement that provide profiles of blood pressure behavior rather than relying on isolated measurements under circumstances that may in themselves influence the level of blood pressure recorded. These methodologies have included repeated measurements of blood pressure using the traditional technique, self-measurement of blood pressure in the home or work place, and ambulatory blood pressure measurement using innovative automated devices. The purpose of this review to serve as a source of practical information about the commonly used methods for blood pressure measurement: the traditional Riva-Rocci method and the automated methods. PMID:17016412

  4. The Indicators’ Inadequacy and the Predictions’ Accuracy

    Constantin Mitruț

    2013-08-01

    Full Text Available In this article, we proposed the introduction in literature of a new source of uncertainty in modeling and forecasting: the indicators’ inadequacy. Even if it was observed, a specific nominalization in the context of forecasting procedure has not been done yet. The inadequacy of indicators as a supplementary source of uncertainty generates a lower degree of accuracy in forecasting. This assumption was proved using empirical data related to the prediction of unemployment rate in Romania on the horizon 2011-2013. Four strategies of modeling and predicting the unemployment rate were proposed, observing two types of indicators’ inadequacy: the use of transformed variables in order to get stationary data set (the difference between the unemployment rates registered in two successive periods was used instead of the unemployment rate and the utilization of macro-regional unemployment rates whose predictions are aggregated in order to forecast the overall unemployment rate in Romania. The results put in evidence that the predictions of the total unemployment rate using moving average models of order 2 are the most accurate, being followed by the forecasts based on the predictions of active civil population and number of unemployed people. The strategies based on the aggregation of the predictions for the four macro-regional unemployment rates imply a higher inadequacy and consequently a lower degree of forecasts’ accuracy.

  5. Dust trajectory sensor: Accuracy and data analysis

    The Dust Trajectory Sensor (DTS) instrument is developed for the measurement of the velocity vector of cosmic dust particles. The trajectory information is imperative in determining the particles' origin and distinguishing dust particles from different sources. The velocity vector also reveals information on the history of interaction between the charged dust particle and the magnetospheric or interplanetary space environment. The DTS operational principle is based on measuring the induced charge from the dust on an array of wire electrodes. In recent work, the DTS geometry has been optimized [S. Auer, E. Gruen, S. Kempf, R. Srama, A. Srowig, Z. Sternovsky, and V Tschernjawski, Rev. Sci. Instrum. 79, 084501 (2008)] and a method of triggering was developed [S. Auer, G. Lawrence, E. Gruen, H. Henkel, S. Kempf, R. Srama, and Z. Sternovsky, Nucl. Instrum. Methods Phys. Res. A 622, 74 (2010)]. This article presents the method of analyzing the DTS data and results from a parametric study on the accuracy of the measurements. A laboratory version of the DTS has been constructed and tested with particles in the velocity range of 2-5 km/s using the Heidelberg dust accelerator facility. Both the numerical study and the analyzed experimental data show that the accuracy of the DTS instrument is better than about 1% in velocity and 1 deg. in direction.

  6. Accuracy of MR in growth plate measurement

    Shiguetomi-Medina, Juan Manuel [Aarhus University, Orthopaedic Research Laboratory, Aarhus University Hospital NBG, Aarhus C (Denmark); Rahbek, Ole [Aarhus University Hospital NBG, Department of Children' s Orthopaedics, Aarhus C (Denmark); Ringgaard, Steffen; Kristiansen, Maja Sofie; Stoedkilde-Joergensen, Hans [Aarhus University Hospital, Skejby, The MR Research Center, Aarhus N (Denmark); Moeller-Madsen, Bjarne [Aarhus University, Orthopaedic Research Laboratory, Aarhus University Hospital NBG, Aarhus C (Denmark); Aarhus University Hospital NBG, Department of Children' s Orthopaedics, Aarhus C (Denmark)

    2014-09-15

    To analyze the accuracy of growth-plate thickness measurements detected on 1.5-T and 7-T MR images using histology sections as a standard of reference. Four defrosted pig tibiae were 1.5-T MR scanned and one fresh tibia was 7-T MR scanned. The height of the growth plate was measured and compared to histology. Histology measurements showed a mean growth plate thickness of 467 μm (SD = 82.2). The mean growth plate thickness measured in the 7-T MR images was 465 μm (SD = 62.2) and 1,325 μm (SD = 183.5) on 1.5-T MR measurements. We found a better correspondence between the growth plate thickness measured on the 7-T MR and histology samples compared to 1.5 T. The growth plate can be identified and measured with high accuracy using 7-T MR. 1.5-T MR can only describe some morphological characteristics. (orig.)

  7. Accuracy assessment of landslide prediction models

    The increasing population and expansion of settlements over hilly areas has greatly increased the impact of natural disasters such as landslide. Therefore, it is important to developed models which could accurately predict landslide hazard zones. Over the years, various techniques and models have been developed to predict landslide hazard zones. The aim of this paper is to access the accuracy of landslide prediction models developed by the authors. The methodology involved the selection of study area, data acquisition, data processing and model development and also data analysis. The development of these models are based on nine different landslide inducing parameters i.e. slope, land use, lithology, soil properties, geomorphology, flow accumulation, aspect, proximity to river and proximity to road. Rank sum, rating, pairwise comparison and AHP techniques are used to determine the weights for each of the parameters used. Four (4) different models which consider different parameter combinations are developed by the authors. Results obtained are compared to landslide history and accuracies for Model 1, Model 2, Model 3 and Model 4 are 66.7, 66.7%, 60% and 22.9% respectively. From the results, rank sum, rating and pairwise comparison can be useful techniques to predict landslide hazard zones

  8. Curation accuracy of model organism databases.

    Keseler, Ingrid M; Skrzypek, Marek; Weerasinghe, Deepika; Chen, Albert Y; Fulcher, Carol; Li, Gene-Wei; Lemmer, Kimberly C; Mladinich, Katherine M; Chow, Edmond D; Sherlock, Gavin; Karp, Peter D

    2014-01-01

    Manual extraction of information from the biomedical literature-or biocuration-is the central methodology used to construct many biological databases. For example, the UniProt protein database, the EcoCyc Escherichia coli database and the Candida Genome Database (CGD) are all based on biocuration. Biological databases are used extensively by life science researchers, as online encyclopedias, as aids in the interpretation of new experimental data and as golden standards for the development of new bioinformatics algorithms. Although manual curation has been assumed to be highly accurate, we are aware of only one previous study of biocuration accuracy. We assessed the accuracy of EcoCyc and CGD by manually selecting curated assertions within randomly chosen EcoCyc and CGD gene pages and by then validating that the data found in the referenced publications supported those assertions. A database assertion is considered to be in error if that assertion could not be found in the publication cited for that assertion. We identified 10 errors in the 633 facts that we validated across the two databases, for an overall error rate of 1.58%, and individual error rates of 1.82% for CGD and 1.40% for EcoCyc. These data suggest that manual curation of the experimental literature by Ph.D-level scientists is highly accurate. Database URL: http://ecocyc.org/, http://www.candidagenome.org// PMID:24923819

  9. The IBIS / ISGRI Source Location Accuracy

    Gros, A; Soldi, S; Gotz, D; Caballero, I; Mattana, F; Heras, J A Zurita

    2013-01-01

    We present here results on the source location accuracy of the INTEGRAL IBIS/ISGRI coded mask telescope, based on ten years of INTEGRAL data and on recent developments in the data analysis procedures. Data were selected and processed with the new Off-line Scientific Analysis pipeline (OSA10.0) that benefits from the most accurate background corrections, the most performing coding noise cleaning and sky reconstruction algorithms available. We obtained updated parameters for the evaluation of the point source location error from the source signal to noise ratio. These results are compared to previous estimates and to theoretical expectations. Also thanks to a new fitting procedure the typical error at 90% confidence level for a source at a signal to noise of 10 is now estimated to be 1.5 arcmin. Prospects for future analysis on the Point Spread Function fitting procedure and on the evaluation of residual biases are also presented. The new consolidated parameters describing the source location accuracy that will...

  10. Enhancing Accuracy of Plant Leaf Classification Techniques

    C. S. Sumathi

    2014-03-01

    Full Text Available Plants have become an important source of energy, and are a fundamental piece in the puzzle to solve the problem of global warming. Living beings also depend on plants for their food, hence it is of great importance to know about the plants growing around us and to preserve them. Automatic plant leaf classification is widely researched. This paper investigates the efficiency of learning algorithms of MLP for plant leaf classification. Incremental back propagation, Levenberg–Marquardt and batch propagation learning algorithms are investigated. Plant leaf images are examined using three different Multi-Layer Perceptron (MLP modelling techniques. Back propagation done in batch manner increases the accuracy of plant leaf classification. Results reveal that batch training is faster and more accurate than MLP with incremental training and Levenberg– Marquardt based learning for plant leaf classification. Various levels of semi-batch training used on 9 species of 15 sample each, a total of 135 instances show a roughly linear increase in classification accuracy.

  11. Dimensional accuracy of 3D printed vertebra

    Ogden, Kent; Ordway, Nathaniel; Diallo, Dalanda; Tillapaugh-Fay, Gwen; Aslan, Can

    2014-03-01

    3D printer applications in the biomedical sciences and medical imaging are expanding and will have an increasing impact on the practice of medicine. Orthopedic and reconstructive surgery has been an obvious area for development of 3D printer applications as the segmentation of bony anatomy to generate printable models is relatively straightforward. There are important issues that should be addressed when using 3D printed models for applications that may affect patient care; in particular the dimensional accuracy of the printed parts needs to be high to avoid poor decisions being made prior to surgery or therapeutic procedures. In this work, the dimensional accuracy of 3D printed vertebral bodies derived from CT data for a cadaver spine is compared with direct measurements on the ex-vivo vertebra and with measurements made on the 3D rendered vertebra using commercial 3D image processing software. The vertebra was printed on a consumer grade 3D printer using an additive print process using PLA (polylactic acid) filament. Measurements were made for 15 different anatomic features of the vertebral body, including vertebral body height, endplate width and depth, pedicle height and width, and spinal canal width and depth, among others. It is shown that for the segmentation and printing process used, the results of measurements made on the 3D printed vertebral body are substantially the same as those produced by direct measurement on the vertebra and measurements made on the 3D rendered vertebra.

  12. ASSESSMENT OF THE THEMATIC ACCURACY OF LAND COVER MAPS

    Høhle, Joachim

    user’s and producer’s accuracy, and kappa coefficient. In addition, confidence intervals were computed for several accuracy measures. The achieved accuracies and confidence intervals are thoroughly analysed and recommendations are derived from the gained experiences. Reliable reference values are...... methods perform equally for five classes. Trees are classified with a much better accuracy and a smaller confidence interval by means of the decision tree method. Buildings are classified by both methods with an accuracy of 99% (95% CI: 95%-100%) using independent 3D checkpoints. The average width of the...... confidence interval of six classes was 14% of the user’s accuracy....

  13. Improving the Accuracy of Cosmic Magnification Statistics

    Ménard, B; Yoshida, M B N; Menard, Brice; Hamana, Takashi; Yoshida, Matthias Bartelmann & Naoki

    2003-01-01

    The systematic magnification of background sources by the weak gravitational-lensing effects of foreground matter, also called cosmic magnification, is becoming an efficient tool both for measuring cosmological parameters and for exploring the distribution of galaxies relative to the dark matter. We extend here the formalism of magnification statistics by estimating the contribution of second-order terms in the Taylor expansion of the magnification and show that the effect of these terms was previously underestimated. We test our analytical predictions against numerical simulations and demonstrate that including second-order terms allows the accuracy of magnification-related statistics to be substantially improved. We also show, however, that both numerical and analytical estimates can provide only lower bounds to real correlation functions, even in the weak lensing regime. We propose to use count-in-cells estimators rather than correlation functions for measuring cosmic magnification since they can more easi...

  14. High accuracy 3-D laser radar

    Busck, Jens; Heiselberg, Henning

    2004-01-01

    We have developed a mono-static staring 3-D laser radar based on gated viewing with range accuracy below 1 m at 10 m and 1 cm at 100. We use a high sensitivity, fast, intensified CCD camera, and a Nd:Yag passively Q-switched 32.4 kHz pulsed green laser at 532 nm. The CCD has 752x582 pixels. Camera...... shutter is controlled in steps of 100 ps. Camera delay is controlled in steps of 100 ps. Each laser pulse triggers the camera delay and shutter. A 3-D image is constructed from a sequence of 50-100 2-D reflectivity images, where each frame integrates about 700 laser pulses on the CCD. In 50 Hz video mode...

  15. Comparative diagnostic accuracy in virtual dermatopathology

    Mooney, E.; Hood, A.F.; Lampros, J.;

    2011-01-01

    Background: Virtual microscopy can be used to teach histology and pathology and for in-training and certification examinations. A few online consultation websites already utilize virtual microscopy, thereby expanding the role of telemedicine in dermatopathology. There are, however, relatively few...... studies comparing the diagnostic accuracy and acceptability of virtual slides compared to traditional glass slides. Methods: Ten Nordic dermatopathologists and pathologists were given a randomized combination of 20 virtual and glass slides and asked to identify the diagnoses. They were then asked to give...... their impressions about the virtual images. Descriptive data analysis and comparison of groups using Fisher's exact test were performed. Objective: To compare the diagnostic ability of dermatopathologists and pathologists in two image formats: the traditional (glass) microscopic slides, and whole mount...

  16. On the accuracy of the Debye shielding

    Martínez-Fuentes, M A

    2012-01-01

    The expression for the Debye shielding in plasma physics is usually derived under the assumptions that the plasma particles are weakly coupled, so their kinetic energy is much larger than the potential energy between them, and that the velocity distributions of the plasma species are Maxwellian. The first assumption also establishes that the plasma parameter ND, the number of particles within a sphere with a Debye radius should be greater than 1, and determines the difference between weakly and strongly coupled plasmas. Under such assumptions, Poisson's equation can be linearised, and a simple analytic expression obtained for the electrostatic potential. However, textbooks rarely discuss the accuracy of this approximation. In this work we compare the linearised solution with the exact one, obtained numerically, and show that the linearisation, which underestimates the exact solution, is reasonably good even for ND ~ 40. We give quantitative criteria to set the limit of the approximation when the number of par...

  17. Accuracy verification methods theory and algorithms

    Mali, Olli; Repin, Sergey

    2014-01-01

    The importance of accuracy verification methods was understood at the very beginning of the development of numerical analysis. Recent decades have seen a rapid growth of results related to adaptive numerical methods and a posteriori estimates. However, in this important area there often exists a noticeable gap between mathematicians creating the theory and researchers developing applied algorithms that could be used in engineering and scientific computations for guaranteed and efficient error control.   The goals of the book are to (1) give a transparent explanation of the underlying mathematical theory in a style accessible not only to advanced numerical analysts but also to engineers and students; (2) present detailed step-by-step algorithms that follow from a theory; (3) discuss their advantages and drawbacks, areas of applicability, give recommendations and examples.

  18. Quantitative code accuracy evaluation of ISP33

    Kalli, H.; Miwrrin, A. [Lappeenranta Univ. of Technology (Finland); Purhonen, H. [VTT Energy, Lappeenranta (Finland)] [and others

    1995-09-01

    Aiming at quantifying code accuracy, a methodology based on the Fast Fourier Transform has been developed at the University of Pisa, Italy. The paper deals with a short presentation of the methodology and its application to pre-test and post-test calculations submitted to the International Standard Problem ISP33. This was a double-blind natural circulation exercise with a stepwise reduced primary coolant inventory, performed in PACTEL facility in Finland. PACTEL is a 1/305 volumetrically scaled, full-height simulator of the Russian type VVER-440 pressurized water reactor, with horizontal steam generators and loop seals in both cold and hot legs. Fifteen foreign organizations participated in ISP33, with 21 blind calculations and 20 post-test calculations, altogether 10 different thermal hydraulic codes and code versions were used. The results of the application of the methodology to nine selected measured quantities are summarized.

  19. Accuracy of calculation of neutron detection efficiency

    The problems of the accuracy for the scintillator spectrometer calculation of neutron recording efficiency value are discussed. The calculation is performed by the method of direct simulation of neutron interaction with the scintillator substance. The preliminary calculations show that a contribution to efficiency of neutron recording in the range of energies of 10 through 50 MeV due to interaction of neutrons with carbon is mostly determined by reactions 12(in n' 2α)4He and 12(n, n' p)11B. The effciency calculation results are given for the cylindrical crystal of stilbene. Measurements of the neutron recording efficiency in the range of energies from 10 MeV indicate a good agreement between the calculation and the experiment

  20. Multi-Accuracy-Level Burning Plasma Simulations

    The design of a reactor grade tokamak is based on a hierarchy of tools. We present here three codes that are presently used for the simulations of burning plasmas. At the first level there is a 0-dimensional code that allows to choose a reasonable range of global parameters; in our case the HELIOS code was used for this task. For the second level we have developed a mixed 0-D / 1-D code called METIS that allows to study the main properties of a burning plasma, including profiles and all heat and current sources, but always under the constraint of energy and other empirical scaling laws. METIS is a fast code that permits to perform a large number of runs (a run takes about one minute) and design the main features of a scenario, or validate the results of the 0-D code on a full time evolution. At the top level, we used the full 1D1/2 suite of codes CRONOS that gives access to a detailed study of the plasma profiles evolution. CRONOS can use a variety of modules for source terms and transport coefficients computation with different level of complexity and accuracy: from simple estimators to highly sophisticated physics calculations. Thus it is possible to vary the accuracy of burning plasma simulations, as a trade-off with computation time. A wide range of scenario studies can thus be made with CRONOS and then validated with post-processing tools like MHD stability analysis. We will present in this paper results of this multi-level analysis applied to the ITER hybrid scenario. This specific example will illustrate the importance of having several tools for the study of burning plasma scenarios, especially in a domain that present devices cannot access experimentally. (Author)

  1. Dosimetric accuracy of a staged radiosurgery treatment

    Cernica, George; de Boer, Steven F.; Diaz, Aidnag; Fenstermaker, Robert A.; Podgorsak, Matthew B.

    2005-05-01

    For large cerebral arteriovenous malformations (AVMs), the efficacy of radiosurgery is limited since the large doses necessary to produce obliteration may increase the risk of radiation necrosis to unacceptable levels. An alternative is to stage the radiosurgery procedure over multiple stages (usually two), effectively irradiating a smaller volume of the AVM nidus with a therapeutic dose during each session. The difference between coordinate systems defined by sequential stereotactic frame placements can be represented by a translation and a rotation. A unique transformation can be determined based on the coordinates of several fiducial markers fixed to the skull and imaged in each stereotactic coordinate system. Using this transformation matrix, isocentre coordinates from the first stage can be displayed in the coordinate system of subsequent stages allowing computation of a combined dose distribution covering the entire AVM. The accuracy of this approach was tested on an anthropomorphic head phantom and was verified dosimetrically. Subtle defects in the phantom were used as control points, and 2 mm diameter steel balls attached to the surface were used as fiducial markers and reference points. CT images (2 mm thick) were acquired. Using a transformation matrix developed with two frame placements, the predicted locations of control and reference points had an average error of 0.6 mm near the fiducial markers and 1.0 mm near the control points. Dose distributions in a staged treatment approach were accurately calculated using the transformation matrix. This approach is simple, fast and accurate. Errors were small and clinically acceptable for Gamma Knife radiosurgery. Accuracy can be improved by reducing the CT slice thickness.

  2. Meteor orbit determination with improved accuracy

    Dmitriev, Vasily; Lupovla, Valery; Gritsevich, Maria

    2015-08-01

    Modern observational techniques make it possible to retrive meteor trajectory and its velocity with high accuracy. There has been a rapid rise in high quality observational data accumulating yearly. This fact creates new challenges for solving the problem of meteor orbit determination. Currently, traditional technique based on including corrections to zenith distance and apparent velocity using well-known Schiaparelli formula is widely used. Alternative approach relies on meteoroid trajectory correction using numerical integration of equation of motion (Clark & Wiegert, 2011; Zuluaga et al., 2013). In our work we suggest technique of meteor orbit determination based on strict coordinate transformation and integration of differential equation of motion. We demonstrate advantage of this method in comparison with traditional technique. We provide results of calculations by different methods for real, recently occurred fireballs, as well as for simulated cases with a priori known retrieval parameters. Simulated data were used to demonstrate the condition, when application of more complex technique is necessary. It was found, that for several low velocity meteoroids application of traditional technique may lead to dramatically delusion of orbit precision (first of all, due to errors in Ω, because this parameter has a highest potential accuracy). Our results are complemented by analysis of sources of perturbations allowing to quantitatively indicate which factors have to be considered in orbit determination. In addition, the developed method includes analysis of observational error propagation based on strict covariance transition, which is also presented.Acknowledgements. This work was carried out at MIIGAiK and supported by the Russian Science Foundation, project No. 14-22-00197.References:Clark, D. L., & Wiegert, P. A. (2011). A numerical comparison with the Ceplecha analytical meteoroid orbit determination method. Meteoritics & Planetary Science, 46(8), pp. 1217

  3. Improvement in measurement accuracy for hybrid scanner

    The capability to provide dense three-dimensional (3D) data (point clouds) at high speed and at high accuracy has made terrestrial laser scanners (TLS) widely used for many purposes especially for documentation, management and analysis. However, similar to other 3D sensors, proper understanding regarding the error sources is necessary to ensure high quality data. A procedure known as calibration is employed to evaluate these errors. This process is crucial for TLS in order to make it suitable for accurate 3D applications (e.g. industrial measurement, reverse engineering and monitoring). Two calibration procedures available for TLS: 1) component, and 2) system calibration. The requirements of special laboratories and tools which are not affordable by most TLS users have become principle drawback for component calibration. In contrast, system calibration only requires a room with appropriate targets. By employing optimal network configuration, this study has performed system calibration through self-calibration for Leica ScanStation C10 scanner. A laboratory with dimensions of 15.5 m × 9 m × 3 m and 138 well-distributed planar targets were used to derive four calibration parameters. Statistical analysis (e.g. t-test) has shown that only two calculated parameters, the constant rangefinder offset error (0.7 mm) and the vertical circle index error (−45.4) were significant for the calibrated scanner. Photogrammetric technique was utilised to calibrate the 3D test points at the calibration field. By using the test points, the residual pattern of raw data and self-calibration results were plotted into the graph to visually demonstrate the improvement in accuracy for Leica ScanStation C10 scanner

  4. Improving Accuracy of Image Classification Using GIS

    Gupta, R. K.; Prasad, T. S.; Bala Manikavelu, P. M.; Vijayan, D.

    The Remote Sensing signal which reaches sensor on-board the satellite is the complex aggregation of signals (in agriculture field for example) from soil (with all its variations such as colour, texture, particle size, clay content, organic and nutrition content, inorganic content, water content etc.), plant (height, architecture, leaf area index, mean canopy inclination etc.), canopy closure status and atmospheric effects, and from this we want to find say, characteristics of vegetation. If sensor on- board the satellite makes measurements in n-bands (n of n*1 dimension) and number of classes in an image are c (f of c*1 dimension), then considering linear mixture modeling the pixel classification problem could be written as n = m* f +, where m is the transformation matrix of (n*c) dimension and therepresents the error vector (noise). The problem is to estimate f by inverting the above equation and the possible solutions for such problem are many. Thus, getting back individual classes from satellite data is an ill-posed inverse problem for which unique solution is not feasible and this puts limit to the obtainable classification accuracy. Maximum Likelihood (ML) is the constraint mostly practiced in solving such a situation which suffers from the handicaps of assumed Gaussian distribution and random nature of pixels (in-fact there is high auto-correlation among the pixels of a specific class and further high auto-correlation among the pixels in sub- classes where the homogeneity would be high among pixels). Due to this, achieving of very high accuracy in the classification of remote sensing images is not a straight proposition. With the availability of the GIS for the area under study (i) a priori probability for different classes could be assigned to ML classifier in more realistic terms and (ii) the purity of training sets for different thematic classes could be better ascertained. To what extent this could improve the accuracy of classification in ML classifier

  5. Accuracy Assessment Points for Tuzigoot National Monument Vegetation Mapping Project

    National Park Service, Department of the Interior — The accuracy assessment field work was performed in May, 1997 to verify the accuracy of the vegetation communities spatial data developed by the USGS-NPS Vegetation...

  6. Accuracy Assessment Points for Voyageurs National Park Vegetation Mapping Project

    National Park Service, Department of the Interior — Thematic accuracy requirements for the USGS-NPS Vegetation Mapping Program specify 80% accuracy for each map unit that represents USNVC floristic types. A total of...

  7. 12 CFR 740.2 - Accuracy of advertising.

    2010-01-01

    ... 12 Banks and Banking 6 2010-01-01 2010-01-01 false Accuracy of advertising. 740.2 Section 740.2 Banks and Banking NATIONAL CREDIT UNION ADMINISTRATION REGULATIONS AFFECTING CREDIT UNIONS ACCURACY OF ADVERTISING AND NOTICE OF INSURED STATUS § 740.2 Accuracy of advertising. No insured credit union may use...

  8. Treatment accuracy of fractionated stereotactic radiotherapy

    Background and purpose: To assess the geometric accuracy of the delivery of fractionated stereotactic radiotherapy (FSRT) for brain tumours using the Gill-Thomas-Cosman (GTC) relocatable frame. Accuracy of treatment delivery was measured via portal images acquired with an amorphous silicon based electronic portal imager (EPI). Results were used to assess the existing verification process and to review the current margins used for the expansion of clinical target volume (CTV) to planning target volume (PTV). Patients and methods: Patients were immobilized in a GTC frame. Target volume definition was performed on localization CT and MRI scans and a CTV to PTV margin of 5 mm (based on initial experience) was introduced in 3D. A Brown-Roberts-Wells (BRW) fiducial system was used for stereotactic coordinate definition. The existing verification process consisted of an intercomparison of the coordinates of the isocentres and anatomy between the localization and verification CT scans. Treatment was delivered with 6 MV photons using four fixed non-coplanar conformal fields using a multi-leaf collimator. Portal imaging verification consisted of the acquisition of orthogonal images centred through the treatment isocentre. Digitally reconstructed radiographs (DRRs) created from the CT localization scans were used as reference images. Semi-automated matching software was used to quantify set up deviations (displacements and rotations) between reference and portal images. Results: One hundred and twenty six anterior and 123 lateral portal images were available for analysis for set up deviations. For displacements, the total errors in the cranial/caudal direction were shown to have the largest SD's of 1.2 mm, while systematic and random errors reached SD's of 1.0 and 0.7 mm, respectively, in the cranial/caudal direction. The corresponding data for rotational errors (the largest deviation was found in the sagittal plane) was 0.7 deg. SD (total error), 0.5 deg. (systematic) and 0

  9. Mass spectrometry accuracy improvement using two tracers

    The accuracy of the isotopic analyses performed by thermoionization mass spectrometry is limited by the effects of isotopic fractionation that occurs during the evaporation of the sample placed on the filament. It results in a continuous change over time of the isotopic compound determined. In order to determine the factor enabling the isotopic fractionation of the uranium to be adjusted, the mass spectrometers are calibrated by using isotopic standards of uranium. The adjusting factor K, defined as 235U/238U theoretical / 235U/238U determined is independent of the value of the 235U/238U ratio, but it has a relative random error of around +-0.28 to +-0.5%. The completion of very accurate isotopic analyses therefore calls for the application of a severe operational mode. Automation of all the sequences of the analysis appears to be the only valid method for attaining this objective, but it remains a very costly solution. These difficulties motivated the studies on the use of an internal standard for directly correcting the effects of isotopic fractionation, constituted of a 233 and 236 uranium solution of which the 236/233 ratio was determined accurately beforehand

  10. Accuracy preserving surrogate for neutron transport calculations

    Recent advances in reduced order modeling and exact-to-precision generalized perturbation theory are combined in a novel algorithm that constructs a surrogate model for the Boltzmann equation, commonly used in assembly calculations to functionalize the few-group cross-sections in terms of the various assembly types, depletion characteristics, and thermal-hydraulics conditions. First, the algorithm employs reduced order modeling to determine the dominant input parameters, aggregated in the so-called active subspace, using a random sample of first-order derivatives calculated using an adjoint model. Next, exact-to-precision generalized perturbation theory identifies an active subspace for the state solution (i.e., angular flux) and constructs a surrogate model that is parameterized over the active subspace of the input parameters. This approach is shown to significantly reduce computational time needed for the analysis of a large number of model variations, while meeting the user-defined accuracy requirements. Numerical experiments are employed to demonstrate the mechanics and application of the proposed approach to assembly calculations commonly used in reactor physics analysis. (author)

  11. High-accuracy measurements on biperiodical circuits

    Coupled resonators in an assembled structure lose their individuality and in co-operation contribute to the generation of structure modes (resonant frequencies). The resonant frequencies of these modes are the only measurable quantities. In order to predict structural behaviour in a variety of cases, the problem that arises is the extraction of all the parameters characterizing the structure from the measurements mentioned here. If all the modes are confined in a bandwidth that is small with respect to the central frequency, the total coupled resonator system is well represented by a circuit of unknown lumped constants.The structure modes are the solutions of the equation obtained by equating to zero the determinant relevant to the lumped circuit representation. The equation is a polynomial of the squared frequency variable, the degree of which is equal to the number M of circuits.The analysis method described in this paper consists in varying, by an unknown amount, the frequency of a single resonator in the chain. This variation will produce a change in the frequencies of all structure modes. It is possible to find certain invariants linearly dependent on all the unchanged parameters of the circuit. These invariants have an algebraic representation that allows the extraction of the structure parameter values with extremely high accuracy. The proposed method is quite general and, in the present work, we give an example applying the method to the characterization of a side-coupled linac (SCL). (paper)

  12. Needle placement accuracy during stereotactic localization mammography

    Aim: To derive a mathematical model to describe the relationship between lesion position in the breast and measurements derived from the stereoradiographs to enable more accurate sampling of a lesion during stereotactic mammographic needle placement. Materials and methods: The affect that registration errors have on the accuracy of needle placement when identifying the lesion on the stereoradiographs was investigated using the mathematical model. Results: The focus-to-film distance of the x-ray tube and the horizontal distance of the lesion from the centre of rotation have little effect on error. Registration errors for lesions lying at a greater perpendicular distance in the breast from the centre of rotation produce smaller localization errors when compared with lesions sited closer. Lesion registration errors during marking of the stereoradiographs are exacerbated by decreasing the angle of x-ray tube swing. Conclusions: When problems are encountered in making an accurate registration of the lesion on the stereoradiographs, consider the following error reducing strategies: (1) employ an approach that places the lesion the maximum distance away from the film cassette; (2) avoid reducing the angle of tube swing; and (3) consider sampling superficial and deep to, as well as at, the location indicated. The possibility of erroneous tissue sampling should be borne in mind when reviewing the pathology report.

  13. A non-linear learning & classification algorithm that achieves full training accuracy with stellar classification accuracy

    Khogali, Rashid

    2014-01-01

    A fast Non-linear and non-iterative learning and classification algorithm is synthesized and validated. This algorithm named the "Reverse Ripple Effect(R.R.E)", achieves 100% learning accuracy but is computationally expensive upon classification. The R.R.E is a (deterministic) algorithm that super imposes Gaussian weighted functions on training points. In this work, the R.R.E algorithm is compared against known learning and classification techniques/algorithms such as: the Perceptron Criterio...

  14. Kinematics of a striking task: accuracy and speed-accuracy considerations.

    Parrington, Lucy; Ball, Kevin; MacMahon, Clare

    2015-01-01

    Handballing in Australian football (AF) is the most efficient passing method, yet little research exists examining technical factors associated with accuracy. This study had three aims: (a) To explore the kinematic differences between accurate and inaccurate handballers, (b) to compare within-individual successful (hit target) and unsuccessful (missed target) handballs and (c) to assess handballing when both accuracy and speed of ball-travel were combined using a novel approach utilising canonical correlation analysis. Three-dimensional data were collected on 18 elite AF players who performed handballs towards a target. More accurate handballers exhibited a significantly straighter hand-path, slower elbow angular velocity and smaller elbow range of motion (ROM) compared to the inaccurate group. Successful handballs displayed significantly larger trunk ROM, maximum trunk rotation velocity and step-angle and smaller elbow ROM in comparison to the unsuccessful handballs. The canonical model explained 73% of variance shared between the variable sets, with a significant relationship found between hand-path, elbow ROM and maximum elbow angular velocity (predictors) and hand-speed and accuracy (dependant variables). Interestingly, not all parameters were the same across each of the analyses, with technical differences between inaccurate and accurate handballers different from those between successful and unsuccessful handballs in the within-individual analysis. PMID:25079111

  15. Diagnostic accuracy of spirometry in primary care

    Dinant Geert-Jan

    2009-07-01

    Full Text Available Abstract Background To evaluate the sensitivity, specificity and predictive values of spirometry for the diagnosis of chronic obstructive pulmonary disease (COPD and asthma in patients suspected of suffering from an obstructive airway disease (OAD in primary care. Methods Cross sectional diagnostic study of 219 adult patients attending 10 general practices for the first time with complaints suspicious for OAD. All patients underwent spirometry and structured medical histories were documented. All patients received whole-body plethysmography (WBP in a lung function laboratory. The reference standard was the Tiffeneau ratio (FEV1/VC received by the spirometric maneuver during examination with WBP. In the event of inconclusive results, bronchial provocation was performed to determine bronchial hyper-responsiveness (BHR. Asthma was defined as a PC20 fall after inhaling methacholine concentration ≤ 16 mg/ml. Results 90 (41.1% patients suffered from asthma, 50 (22.8% suffered from COPD, 79 (36.1% had no OAD. The sensitivity for diagnosing airway obstruction in COPD was 92% (95%CI 80–97; specificity was 84% (95%CI 77–89. The positive predictive value (PPV was 63% (95%CI 51–73; negative predictive value (NPV was 97% (95%CI 93–99. The sensitivity for diagnosing airway obstruction in asthma was 29% (95%CI 21–39; specificity was 90% (95%CI 81–95. PPV was 77% (95%CI 60–88; NPV was 53% (95%CI 45–61. Conclusion COPD can be estimated with high diagnostic accuracy using spirometry. It is also possible to rule in asthma with spirometry. However, asthma can not be ruled out only using spirometry. This diagnostic uncertainty leads to an overestimation of asthma presence. Patients with inconclusive spirometric results should be referred for nitric oxide (NO – measurement and/or bronchial provocation if possible to guarantee accurate diagnosis.

  16. Accuracy of experimental partial structure factors

    For the discussion of the partial structure factors, a Figure of Merit (T) was suggested to design a proper experimental condition. In order to determine uniquely the partial structure factors in a binary alloy, three experiments are required, in which the scattering power of one or both elements, is varied. The measured scattering factors I(Q) from a binary alloy of composition A(1-x)B(x) are obtained for respective experiments. Then, the solution S(Q) is derived, and the error in I(Q) contributes to the error in S(Q). A measure of conditioning can be derived by the consideration of vector and matrix norms leading to a figure of merit called Turin's number T. The figure of merit, when multiplied by the expected errors in the measured intensity functions, the composition, and/or the values of the scattering length, gives an upper estimate of the expected errors in partial structure factors. In order to assess the accuracy required, a typical partial structure factor (the Pd-Pd pSF from a model of Pd(4)Si) was modified. By carefully choosing the system and optimizing the composition, good T's were able to be found for metallic glass-forming alloys. The best T found to date was for the Ni-Zr system using the Ni58 and Ni62 isotopes, and the T was 4.8. The techniques, which are complementary to the isotopic substitution method in Ni-Zr, are discussed. The expected errors in the partials were found to be small enough for extracting directly useful information. (Kato, T.)

  17. Accuracy of quantitative visual soil assessment

    van Leeuwen, Maricke; Heuvelink, Gerard; Stoorvogel, Jetse; Wallinga, Jakob; de Boer, Imke; van Dam, Jos; van Essen, Everhard; Moolenaar, Simon; Verhoeven, Frank; Stoof, Cathelijne

    2016-04-01

    Visual soil assessment (VSA) is a method to assess soil quality visually, when standing in the field. VSA is increasingly used by farmers, farm organisations and companies, because it is rapid and cost-effective, and because looking at soil provides understanding about soil functioning. Often VSA is regarded as subjective, so there is a need to verify VSA. Also, many VSAs have not been fine-tuned for contrasting soil types. This could lead to wrong interpretation of soil quality and soil functioning when contrasting sites are compared to each other. We wanted to assess accuracy of VSA, while taking into account soil type. The first objective was to test whether quantitative visual field observations, which form the basis in many VSAs, could be validated with standardized field or laboratory measurements. The second objective was to assess whether quantitative visual field observations are reproducible, when used by observers with contrasting backgrounds. For the validation study, we made quantitative visual observations at 26 cattle farms. Farms were located at sand, clay and peat soils in the North Friesian Woodlands, the Netherlands. Quantitative visual observations evaluated were grass cover, number of biopores, number of roots, soil colour, soil structure, number of earthworms, number of gley mottles and soil compaction. Linear regression analysis showed that four out of eight quantitative visual observations could be well validated with standardized field or laboratory measurements. The following quantitative visual observations correlated well with standardized field or laboratory measurements: grass cover with classified images of surface cover; number of roots with root dry weight; amount of large structure elements with mean weight diameter; and soil colour with soil organic matter content. Correlation coefficients were greater than 0.3, from which half of the correlations were significant. For the reproducibility study, a group of 9 soil scientists and 7

  18. Accuracy of quantitative visual soil assessment

    van Leeuwen, Maricke; Heuvelink, Gerard; Stoorvogel, Jetse; Wallinga, Jakob; de Boer, Imke; van Dam, Jos; van Essen, Everhard; Moolenaar, Simon; Verhoeven, Frank; Stoof, Cathelijne

    2016-04-01

    Visual soil assessment (VSA) is a method to assess soil quality visually, when standing in the field. VSA is increasingly used by farmers, farm organisations and companies, because it is rapid and cost-effective, and because looking at soil provides understanding about soil functioning. Often VSA is regarded as subjective, so there is a need to verify VSA. Also, many VSAs have not been fine-tuned for contrasting soil types. This could lead to wrong interpretation of soil quality and soil functioning when contrasting sites are compared to each other. We wanted to assess accuracy of VSA, while taking into account soil type. The first objective was to test whether quantitative visual field observations, which form the basis in many VSAs, could be validated with standardized field or laboratory measurements. The second objective was to assess whether quantitative visual field observations are reproducible, when used by observers with contrasting backgrounds. For the validation study, we made quantitative visual observations at 26 cattle farms. Farms were located at sand, clay and peat soils in the North Friesian Woodlands, the Netherlands. Quantitative visual observations evaluated were grass cover, number of biopores, number of roots, soil colour, soil structure, number of earthworms, number of gley mottles and soil compaction. Linear regression analysis showed that four out of eight quantitative visual observations could be well validated with standardized field or laboratory measurements. The following quantitative visual observations correlated well with standardized field or laboratory measurements: grass cover with classified images of surface cover; number of roots with root dry weight; amount of large structure elements with mean weight diameter; and soil colour with soil organic matter content. Correlation coefficients were greater than 0.3, from which half of the correlations were significant. For the reproducibility study, a group of 9 soil scientists and 7

  19. Influence of Exposure Time on Prototyping Accuracy in Stereolithography

    吴懋亮; 方明伦; 胡庆夕; 戴春祥; 卢秉恒

    2004-01-01

    A novel stereolithgraphy system with conventional UV light as a light source uses the 2D worktable as moving components,whose characteristics determine the accuracy of the prototyping parts. Many factors including mass of the worktable, elasticity and damp coefficients, speed and acceleration affect the non-uniform exposure time of the resin, and eventually influence the cured line shape and the curing accuracy. A light shuttle is used to eliminate the cure errors, greatly improving accuracy of the parts.

  20. Airborne Topographic Mapper Calibration Procedures and Accuracy Assessment

    Martin, Chreston F.; Krabill, William B.; Manizade, Serdar S.; Russell, Rob L.; Sonntag, John G.; Swift, Robert N.; Yungel, James K.

    2012-01-01

    Description of NASA Airborn Topographic Mapper (ATM) lidar calibration procedures including analysis of the accuracy and consistancy of various ATM instrument parameters and the resulting influence on topographic elevation measurements. The ATM elevations measurements from a nominal operating altitude 500 to 750 m above the ice surface was found to be: Horizontal Accuracy 74 cm, Horizontal Precision 14 cm, Vertical Accuracy 6.6 cm, Vertical Precision 3 cm.

  1. Wavelength Calibration Accuracy for the STIS CCD and MAMA Modes

    Pascucci, Ilaria; Hodge, Phil; Proffitt, Charles R.; Ayres, T.

    2011-03-01

    Two calibration programs were carried out to determine the accuracy of the wavelength solutions for the most used STIS CCD and MAMA modes after Servicing Mission 4. We report here on the analysis of this dataset and show that the STIS wavelength solution has not changed after SM4. We also show that a typical accuracy for the absolute wavelength zero-points is 0.1 pixels while the relative wavelength accuracy is 0.2 pixels.

  2. A Suite of Tools for Assessing Thematic Map Accuracy

    Jean-François Mas; Azucena Pérez-Vega; Adrián Ghilardi; Silvia Martínez; Jaime Octavio Loya-Carrillo; Ernesto Vega

    2014-01-01

    Although land use/cover maps are widely used to support management and environmental policies, only some studies have reported their accuracy using sound and complete assessments. Thematic map accuracy assessment is typically achieved by comparing reference sites labeled with the “ground-truth” category to the ones depicted in the land use/cover map. A variety of sampling designs are used to select these references sites. The estimators for accuracy indices and the variance of these estimator...

  3. BENCHMARKING THE ACCURACY OF INERTIAL SENSORS IN CELL PHONES

    An, Bin

    2012-01-01

    Many ubiquitous computing applications rely on data from a cell phone's inertial sensors. Unfortunately, the accuracy of this data is often unknown, which impedes predictive analysis of applications that require high sensor accuracy (e.g., dead reckoning). This work focuses on benchmarking the accuracy of the accelerometers and gyroscopes on a cell phone. The cell phones are attached to a robotic arm, which provides ground truth measurements. The misalignment between the cell phone's and the ...

  4. Achievable precision and accuracy of dose determinations from routine dosemeters

    The concepts of accuracy and precision as associated with dose determinations from routine dosemeters are analyzed. The factors which are most important when considering the accuracy of such measurements are then discussed. These include environmental conditions such as humidity, temperature, dose rate and time since irradiation. Some examples are presented. It is concluded that precision under identical irradiation conditions for reproducibility can be ± 2% at the 95% confidence level. The corresponding accuracy should not be more than ± 5%. (U.K.)

  5. Diagnostic Accuracy of Procalcitonin in Bacterial Meningitis Versus Nonbacterial Meningitis

    Wei, Ting-Ting; Hu, Zhi-De; Qin, Bao-Dong; Ma, Ning; Tang, Qing-Qin; Wang, Li-li; ZHOU, Lin; Zhong, Ren-Qian

    2016-01-01

    Abstract Several studies have investigated the diagnostic accuracy of procalcitonin (PCT) levels in blood or cerebrospinal fluid (CSF) in bacterial meningitis (BM), but the results were heterogeneous. The aim of the present study was to ascertain the diagnostic accuracy of PCT as a marker for BM detection. A systematic search of the EMBASE, Scopus, Web of Science, and PubMed databases was performed to identify studies published before December 7, 2015 investigating the diagnostic accuracy of ...

  6. Emitter location accuracy using TDOA and differential Doppler

    Chestnut, P. C.

    1982-03-01

    The time difference of arrival (TDOA) and the differential Doppler methods for locating a radio or sonar transmitter are described, and some relationships between the accuracy of their measurements and the accuracy of the location estimates obtained from the measurements are presented. The formula for the one-sigma width of the lines of constant TDOA and the differential Doppler on the surface of the earth is used to characterize emitter location accuracy. The derived relations can be used by the systems engineer to evaluate proposed systems and to determine system specifications to satisfy given requirements on emitter location accuracy.

  7. Assessment of the Thematic Accuracy of Land Cover Maps

    Höhle, J.

    2015-08-01

    Several land cover maps are generated from aerial imagery and assessed by different approaches. The test site is an urban area in Europe for which six classes (`building', `hedge and bush', `grass', `road and parking lot', `tree', `wall and car port') had to be derived. Two classification methods were applied (`Decision Tree' and `Support Vector Machine') using only two attributes (height above ground and normalized difference vegetation index) which both are derived from the images. The assessment of the thematic accuracy applied a stratified design and was based on accuracy measures such as user's and producer's accuracy, and kappa coefficient. In addition, confidence intervals were computed for several accuracy measures. The achieved accuracies and confidence intervals are thoroughly analysed and recommendations are derived from the gained experiences. Reliable reference values are obtained using stereovision, false-colour image pairs, and positioning to the checkpoints with 3D coordinates. The influence of the training areas on the results is studied. Cross validation has been tested with a few reference points in order to derive approximate accuracy measures. The two classification methods perform equally for five classes. Trees are classified with a much better accuracy and a smaller confidence interval by means of the decision tree method. Buildings are classified by both methods with an accuracy of 99% (95% CI: 95%-100%) using independent 3D checkpoints. The average width of the confidence interval of six classes was 14% of the user's accuracy.

  8. Accuracy Driven Artificial Neural Networks in Stock Market Prediction

    Selvan Simon

    2012-06-01

    Full Text Available Globalization has made the stock market prediction (SMP accuracy more challenging and rewarding for the researchers and other participants in the stock market. Local and global economic situations alongwith the company’s financial strength and prospects have to be taken into account to improve the prediction accuracy. Artificial Neural Networks (ANN has been identified to be one of the dominant data mining techniques in stock market prediction area. In this paper, we survey different ANN models that have been experimented in SMP with the special enhancement techniques used with them to improve the accuracy. Also, we explore the possible research strategies in this accuracy driven ANN models.

  9. Virtual Teaching Simulation for Robot Assembly Accuracy Analysis

    张征; 周宏甫; 刘斌

    2004-01-01

    In this paper, by teaching a 3D robot unit model and playing back to simulate the assembly process in a virtual assembly environment, errors in robot assembly are analyzed. The paper also presents a visualization method for analyzing accuracy of the robot assembly, and studies the influence of the spatial pose of a robot on the success rate of an axis-hole assembly, and accuracy of the robot teaching program in particular. Through integration of various errors and on the basis of assembly accuracy, tolerance of error sources can be reasonably distributed to meet the assembly accuracy requirement, therefore the planning of robot assembly unit can be improved.

  10. The accuracy of CT - determined femoral neck anteversion

    In order to establish the accuracy of CT determination of femoral neck anteversion, two models were constructed; one an idealized Plexiglas model and the other from a real femur. Experiments were carried out by pre-setting angles on the phantoms, and then determining these angles by CT. The results, which show a high degree of accuracy, are analyzed statistically. (orig.)

  11. Developing a Weighted Measure of Speech Sound Accuracy

    Preston, Jonathan L.; Ramsdell, Heather L.; Oller, D. Kimbrough; Edwards, Mary Louise; Tobin, Stephen J.

    2011-01-01

    Purpose: To develop a system for numerically quantifying a speaker's phonetic accuracy through transcription-based measures. With a focus on normal and disordered speech in children, the authors describe a system for differentially weighting speech sound errors on the basis of various levels of phonetic accuracy using a Weighted Speech Sound…

  12. Aggregate Accuracy under Majority Rule with Heterogeneous Cost Functions

    Minoru Kitahara; Yohei Sekiguchi

    2006-01-01

    We investigate an election model with costly accuracy improvement by allowing heterogeneity in the cost functions. We find that the aggregate accuracy in large elections is characterized by the average value of the inverse of the second derivative at zero information.

  13. Concept Mapping Improves Metacomprehension Accuracy among 7th Graders

    Redford, Joshua S.; Thiede, Keith W.; Wiley, Jennifer; Griffin, Thomas D.

    2012-01-01

    Two experiments explored concept map construction as a useful intervention to improve metacomprehension accuracy among 7th grade students. In the first experiment, metacomprehension was marginally better for a concept mapping group than for a rereading group. In the second experiment, metacomprehension accuracy was significantly greater for a…

  14. The neural basis of the speed-accuracy tradeoff

    R. Bogacz; E.J. Wagenmakers; B.U. Forstmann; S. Nieuwenhuis

    2010-01-01

    In many situations, decision makers need to negotiate between the competing demands of response speed and response accuracy, a dilemma generally known as the speed-accuracy tradeoff (SAT). Despite the ubiquity of SAT, the question of how neural decision circuits implement SAT has received little att

  15. Using inferred probabilities to measure the accuracy of imprecise forecasts

    Paul Lehner

    2012-11-01

    Full Text Available Research on forecasting is effectively limited to forecasts that are expressed with clarity; which is to say that the forecasted event must be sufficiently well-defined so that it can be clearly resolved whether or not the event occurred and forecasts certainties are expressed as quantitative probabilities. When forecasts are expressed with clarity, then quantitative measures (scoring rules, calibration, discrimination, etc. can be used to measure forecast accuracy, which in turn can be used to measure the comparative accuracy of different forecasting methods. Unfortunately most real world forecasts are not expressed clearly. This lack of clarity extends to both the description of the forecast event and to the use of vague language to express forecast certainty. It is thus difficult to assess the accuracy of most real world forecasts, and consequently the accuracy the methods used to generate real world forecasts. This paper addresses this deficiency by presenting an approach to measuring the accuracy of imprecise real world forecasts using the same quantitative metrics routinely used to measure the accuracy of well-defined forecasts. To demonstrate applicability, the Inferred Probability Method is applied to measure the accuracy of forecasts in fourteen documents examining complex political domains. Key words: inferred probability, imputed probability, judgment-based forecasting, forecast accuracy, imprecise forecasts, political forecasting, verbal probability, probability calibration.

  16. 40 CFR 86.1338-2007 - Emission measurement accuracy.

    2010-07-01

    ... 40 Protection of Environment 19 2010-07-01 2010-07-01 false Emission measurement accuracy. 86.1338... Procedures § 86.1338-2007 Emission measurement accuracy. (a) Minimum limit. (1) The minimum limit of an... it will allow a meaningful determination of compliance with respect to the applicable standard....

  17. Follow your breath: Respiratory interoceptive accuracy in experienced meditators

    Daubenmier, J; Sze, J.; Kerr, CE; Kemeny, ME; Mehling, W

    2013-01-01

    Attention to internal bodily sensations is a core feature of mindfulness meditation. Previous studies have not detected differences in interoceptive accuracy between meditators and nonmeditators on heartbeat detection and perception tasks. We compared differences in respiratory interoceptive accuracy between meditators and nonmeditators in the ability to detect and discriminate respiratory resistive loads and sustain accurate perception of respiratory tidal volume during nondistracted and dis...

  18. DESIGNA ND ANALYSIS FOR THEMATIC MAP ACCURACY ASSESSMENT: FUNDAMENTAL PRINCIPLES

    Before being used in scientific investigations and policy decisions, thematic maps constructed from remotely sensed data should be subjected to a statistically rigorous accuracy assessment. The three basic components of an accuracy assessment are: 1) the sampling design used to s...

  19. The accuracy assessment in areal interpolation:An empirical investigation

    2008-01-01

    Areal interpolation is the process of transferring data from source zones to target zones. While method development remains a top research priority in areal interpo-lation,the accuracy assessment aspect also begs for attention. This paper reports an empirical experience on probing an areal interpolation method to highlight the power and potential pitfalls in accuracy assessment. A kriging-based interpolation algorithm is evaluated by several approaches. It is found that accuracy assessment is a powerful tool to understand an interpolation method,e.g. the utility of ancillary data and semi-variogram modeling in kriging in our case study. However,different assessment methods and spatial units on which assessment is conducted can lead to rather different results. The typical practice to assess accuracy at the source zone level may overestimate interpolation accuracy. Assessment at the target zone level is suggested as a supplement.

  20. Testing an Automated Accuracy Assessment Method on Bibliographic Data

    Marlies Olensky

    2014-12-01

    Full Text Available This study investigates automated data accuracy assessment as described in data quality literature for its suitability to assess bibliographic data. The data samples comprise the publications of two Nobel Prize winners in the field of Chemistry for a 10-year-publication period retrieved from the two bibliometric data sources, Web of Science and Scopus. The bibliographic records are assessed against the original publication (gold standard and an automatic assessment method is compared to a manual one. The results show that the manual assessment method reflects truer accuracy scores. The automated assessment method would need to be extended by additional rules that reflect specific characteristics of bibliographic data. Both data sources had higher accuracy scores per field than accumulated per record. This study contributes to the research on finding a standardized assessment method of bibliographic data accuracy as well as defining the impact of data accuracy on the citation matching process.

  1. Accuracy of 11-year-olds selfreported school lunch consumption

    Lyng, Nina

    studies among children has addressed accuracy in relation to school meals. However, in several countries including Denmark packed lunch is the prevalent lunch format and the lack of packed lunch reporting accuracy studies needs to be addressed to increase the knowledge about school hour reporting accuracy......) 2- To assess reporting accuracy in relation to gender and self-reported methods (Paper I) 3- To address aspects of reporting inaccuracy from intrusions by food group, against different objective measures, and classification of intrusions in stretches and confabulations (Paper II) 4- To assess how...... reporting accuracy differ by the lunch format consumed (Paper III) Material and methods The study was conducted as a cross-sectional dietary reporting study. The population consisted of 11-year-old children from three public schools in Copenhagen. The study was conducted on two consecutive days and assessed...

  2. Application of function generator for checking reactivity meter accuracy

    The accuracy of reactivity meters is usually checked with a reactor kinetic simulator operating to an accuracy exceeding the expected accuracy of the measuring device. The present report describes a method to evaluate accuracy by comparing the response R(t) of the reactivity meter to a given function n(t) with the value of the reactivity function r(t) calculated from the same input function instead of using the input reference signal r(t) to the simulator with the output signal R(t) from the reactivity meter. This method has been successfully used by applying sawtooth and exponential input signals for the determination of the accuracy of reactivity meters developed in the Central Research Institute for Physics. (author)

  3. Accuracy of endoscopic ultrasonography for diagnosing ulcerative early gastric cancers.

    Park, Jin-Seok; Kim, Hyungkil; Bang, Byongwook; Kwon, Kyesook; Shin, Youngwoon

    2016-07-01

    Although endoscopic ultrasonography (EUS) is the first-choice imaging modality for predicting the invasion depth of early gastric cancer (EGC), the prediction accuracy of EUS is significantly decreased when EGC is combined with ulceration.The aim of present study was to compare the accuracy of EUS and conventional endoscopy (CE) for determining the depth of EGC. In addition, the various clinic-pathologic factors affecting the diagnostic accuracy of EUS, with a particular focus on endoscopic ulcer shapes, were evaluated.We retrospectively reviewed data from 236 consecutive patients with ulcerative EGC. All patients underwent EUS for estimating tumor invasion depth, followed by either curative surgery or endoscopic treatment. The diagnostic accuracy of EUS and CE was evaluated by comparing the final histologic result of resected specimen. The correlation between accuracy of EUS and characteristics of EGC (tumor size, histology, location in stomach, tumor invasion depth, and endoscopic ulcer shapes) was analyzed. Endoscopic ulcer shapes were classified into 3 groups: definite ulcer, superficial ulcer, and ill-defined ulcer.The overall accuracy of EUS and CE for predicting the invasion depth in ulcerative EGC was 68.6% and 55.5%, respectively. Of the 236 patients, 36 patients were classified as definite ulcers, 98 were superficial ulcers, and 102 were ill-defined ulcers, In univariate analysis, EUS accuracy was associated with invasion depth (P = 0.023), tumor size (P = 0.034), and endoscopic ulcer shapes (P = 0.001). In multivariate analysis, there is a significant association between superficial ulcer in CE and EUS accuracy (odds ratio: 2.977; 95% confidence interval: 1.255-7.064; P = 0.013).The accuracy of EUS for determining tumor invasion depth in ulcerative EGC was superior to that of CE. In addition, ulcer shape was an important factor that affected EUS accuracy. PMID:27472672

  4. 40 CFR 53.53 - Test for flow rate accuracy, regulation, measurement accuracy, and cut-off.

    2010-07-01

    ... the sampler such that the sampler flow rate can be manually restricted during the test. (f) Procedure... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Test for flow rate accuracy, regulation... Class II Equivalent Methods for PM2.5 or PM10â2.5 § 53.53 Test for flow rate accuracy,...

  5. Systematic Calibration for Ultra-High Accuracy Inertial Measurement Units.

    Cai, Qingzhong; Yang, Gongliu; Song, Ningfang; Liu, Yiliang

    2016-01-01

    An inertial navigation system (INS) has been widely used in challenging GPS environments. With the rapid development of modern physics, an atomic gyroscope will come into use in the near future with a predicted accuracy of 5 × 10(-6)°/h or better. However, existing calibration methods and devices can not satisfy the accuracy requirements of future ultra-high accuracy inertial sensors. In this paper, an improved calibration model is established by introducing gyro g-sensitivity errors, accelerometer cross-coupling errors and lever arm errors. A systematic calibration method is proposed based on a 51-state Kalman filter and smoother. Simulation results show that the proposed calibration method can realize the estimation of all the parameters using a common dual-axis turntable. Laboratory and sailing tests prove that the position accuracy in a five-day inertial navigation can be improved about 8% by the proposed calibration method. The accuracy can be improved at least 20% when the position accuracy of the atomic gyro INS can reach a level of 0.1 nautical miles/5 d. Compared with the existing calibration methods, the proposed method, with more error sources and high order small error parameters calibrated for ultra-high accuracy inertial measurement units (IMUs) using common turntables, has a great application potential in future atomic gyro INSs. PMID:27338408

  6. Systematic Calibration for Ultra-High Accuracy Inertial Measurement Units

    Qingzhong Cai

    2016-06-01

    Full Text Available An inertial navigation system (INS has been widely used in challenging GPS environments. With the rapid development of modern physics, an atomic gyroscope will come into use in the near future with a predicted accuracy of 5 × 10−6°/h or better. However, existing calibration methods and devices can not satisfy the accuracy requirements of future ultra-high accuracy inertial sensors. In this paper, an improved calibration model is established by introducing gyro g-sensitivity errors, accelerometer cross-coupling errors and lever arm errors. A systematic calibration method is proposed based on a 51-state Kalman filter and smoother. Simulation results show that the proposed calibration method can realize the estimation of all the parameters using a common dual-axis turntable. Laboratory and sailing tests prove that the position accuracy in a five-day inertial navigation can be improved about 8% by the proposed calibration method. The accuracy can be improved at least 20% when the position accuracy of the atomic gyro INS can reach a level of 0.1 nautical miles/5 d. Compared with the existing calibration methods, the proposed method, with more error sources and high order small error parameters calibrated for ultra-high accuracy inertial measurement units (IMUs using common turntables, has a great application potential in future atomic gyro INSs.

  7. Accuracy of blood pressure monitors available in high street pharmacies.

    Ware, Adam; Stevens, Richard; Selwood, Mary; Fleming, Susannah

    2016-02-01

    The aim of this study was to assess the accuracy of automated blood pressure monitors on sale to the UK general public. We conducted static pressure accuracy testing on all compatible (19 out of 22 available) blood pressure monitors available for sale in pharmacies within the city of Oxford, UK, and tested two devices for accuracy in measurement of systolic and diastolic blood pressures in 21 adults. The devices showed good accuracy when measuring static pressure in laboratory bench testing, with the median error per device ranging from -2.2 to +1.2 mmHg; however, the two devices tested performed worse in vivo than in laboratory tests, with median errors as high as 6 mmHg. The monitors showed good accuracy in static pressure testing, with a lack of correlation between monitor price and accuracy. However, higher error rates seen during in-vivo testing of a subset of monitors may indicate that static testing may not be appropriate for routine accuracy assessment of these monitors. PMID:26427055

  8. Systematic Calibration for Ultra-High Accuracy Inertial Measurement Units

    Cai, Qingzhong; Yang, Gongliu; Song, Ningfang; Liu, Yiliang

    2016-01-01

    An inertial navigation system (INS) has been widely used in challenging GPS environments. With the rapid development of modern physics, an atomic gyroscope will come into use in the near future with a predicted accuracy of 5 × 10−6°/h or better. However, existing calibration methods and devices can not satisfy the accuracy requirements of future ultra-high accuracy inertial sensors. In this paper, an improved calibration model is established by introducing gyro g-sensitivity errors, accelerometer cross-coupling errors and lever arm errors. A systematic calibration method is proposed based on a 51-state Kalman filter and smoother. Simulation results show that the proposed calibration method can realize the estimation of all the parameters using a common dual-axis turntable. Laboratory and sailing tests prove that the position accuracy in a five-day inertial navigation can be improved about 8% by the proposed calibration method. The accuracy can be improved at least 20% when the position accuracy of the atomic gyro INS can reach a level of 0.1 nautical miles/5 d. Compared with the existing calibration methods, the proposed method, with more error sources and high order small error parameters calibrated for ultra-high accuracy inertial measurement units (IMUs) using common turntables, has a great application potential in future atomic gyro INSs. PMID:27338408

  9. Accuracy of spinal navigation for Magerl-screws

    Study design: assessment of the accuracy of frameless stereotactic navigation at the second cervical vertebra. Objectives: to assess the influence of the protocol of preoperative CT-scan and the registration technique on the accuracy of navigation for implanting Magerl-screws. Summary of background data: the use of navigation systems for implanting Magerl-screws could help to decrease the risk of complications and to reduce the required skin incision. Two parameters conceivably affecting the accuracy are the protocol of the preoperative CT-scan and the registration technique. Methods: four cervical spine segments of human cadavers were scanned with two different protocols (3 mm slice thickness/2 mm table increment, 1 mm slice thickness/1 mm table increment). Registration was performed either based on anatomical landmarks or using a specially designed percutaneous registration device. For the accuracy-check, the pointer tip was exactly placed on markers. The distance between the pointer and the marker displayed on the monitor was referred as an estimate of accuracy. Results: varying the CT-protocol did not significantly affect the accuracy. The mean accuracy was improved from 3 mm after anatomical pair point matching to 1.5 mm after matching using the percutaneous registration device. Conclusions: the accuracy obtainable seems to be sufficient for implanting Magerl screws by using frameless stereotactic navigation. 3 mm slice thickness and 2 mm table increment is a proper protocol for the preoperative CT-scan. To obtain the highest accuracy possible, fiducial markers like the percutaneous registration device should be used for registration. (author)

  10. Do Shared Interests Affect the Accuracy of Budgets?

    Ilse Maria Beuren; Franciele Beck; Fabiane Popik

    2015-01-01

    The creation of budgetary slack is a phenomenon associated with various behavioral aspects. This study focuses on accuracy in budgeting when the benefit of the slack is shared between the unit manager and his/her assistant. In this study, accuracy is measured by the level of slack in the budget, and the benefit of slack represents a financial consideration for the manager and the assistant. The study aims to test how shared interests in budgetary slack affect the accuracy of budget reports in...

  11. Accuracy and performance analysis of a nuclear belt weigher

    Nuclear belt weighers have a broad range of applications in the solid particle industry. This work analyzes the accuracy and sensitivity of nuclear weighers for a wide range of operational conditions and design parameters. The problem of the effect of material profile and bulk density variations on the scale performance is quantitatively addressed. A new methodology is developed to calculate the minimum detectable load accounting for both accuracy and sensitivity. Accuracies of less than 1% can be achieved in some ideal situations by proper design of the source length and geometrical configuration. (orig.)

  12. Precise Computation of Position Accuracy in GNSS Systems

    Garrido, Juan Pablo Boyero

    2011-01-01

    Accuracy and Availability computations for a GNSS System - or combination of Systems - through Service Volume Simulations take considerable time. Therefore, the computation of the accuracy in 2D and 3D are often simplified by an approximate solution. The drawback is that such simplifications can lead to accuracy results that are too conservative (up to 25% in the 2D case and up to 43% in the 3D case, for a 95% confidence level), which in turn translates into pessimistic System Availability. T...

  13. Required accuracy and dose thresholds in individual monitoring

    Christensen, P.; Griffith, R.V.

    specification of detailed accuracy requirements which are needed in practical routine monitoring. The ICRP overall accuracy requirement is defined as an allowable maximum uncertainty factor at the 95% confidence level for a single measurement of the relevant dose quantity, i.e. H(p)(10) and H(p)(0.07). From......The paper follows the approach given in recent revisions of CEC and IAEA recommendations on requirements in individual monitoring for external radiations. The ICRP requirements on overall accuracy for individual monitoring, as given in ICRP Publication 35 (1982), form the basis for the...

  14. Art and accuracy: the drawing ability of idiot-savants.

    Hermelin, B; O'Connor, N

    1990-01-01

    The accuracy and the artistic merit of drawings produced by graphically gifted idiot-savants and by artistically able normal children were investigated in various conditions. Drawings had to be executed when a three- or two-dimensional model of the scene to be drawn was in view, or when it had to be remembered or drawn from another viewpoint. It was found that overall accuracy was better for the normal than for the mentally handicapped subjects. In contrast, ratings for artistic merit did not differentiate the groups. It is concluded that while the accuracy of drawings may be related to intelligence, the artistic quality of the graphic production is not. PMID:2312650

  15. Inertial measures of motion for clinical biomechanics: comparative assessment of accuracy under controlled conditions - changes in accuracy over time.

    Karina Lebel

    Full Text Available Interest in 3D inertial motion tracking devices (AHRS has been growing rapidly among the biomechanical community. Although the convenience of such tracking devices seems to open a whole new world of possibilities for evaluation in clinical biomechanics, its limitations haven't been extensively documented. The objectives of this study are: 1 to assess the change in absolute and relative accuracy of multiple units of 3 commercially available AHRS over time; and 2 to identify different sources of errors affecting AHRS accuracy and to document how they may affect the measurements over time.This study used an instrumented Gimbal table on which AHRS modules were carefully attached and put through a series of velocity-controlled sustained motions including 2 minutes motion trials (2MT and 12 minutes multiple dynamic phases motion trials (12MDP. Absolute accuracy was assessed by comparison of the AHRS orientation measurements to those of an optical gold standard. Relative accuracy was evaluated using the variation in relative orientation between modules during the trials.Both absolute and relative accuracy decreased over time during 2MT. 12MDP trials showed a significant decrease in accuracy over multiple phases, but accuracy could be enhanced significantly by resetting the reference point and/or compensating for initial Inertial frame estimation reference for each phase.The variation in AHRS accuracy observed between the different systems and with time can be attributed in part to the dynamic estimation error, but also and foremost, to the ability of AHRS units to locate the same Inertial frame.Mean accuracies obtained under the Gimbal table sustained conditions of motion suggest that AHRS are promising tools for clinical mobility assessment under constrained conditions of use. However, improvement in magnetic compensation and alignment between AHRS modules are desirable in order for AHRS to reach their full potential in capturing clinical outcomes.

  16. Prenatal diagnosis of cardiac defects : accuracy and benefit

    Clur, S. A.; Van Brussel, P. M.; Ottenkamp, J.; Bilardo, C. M.

    2012-01-01

    Objective The prenatal diagnosis of cardiac defects can potentially reduce postnatal morbidity and mortality. We wanted to evaluate prenatal cardiac diagnosis accuracy in a population referred for echocardiography. Methods Single centre retrospective study of echocardiography referrals between April

  17. Accuracy Assessment Points for Dinosaur National Monument Vegetation Mapping Project

    National Park Service, Department of the Interior — This point file displays the 1543 accuracy assessment (AA) points visited in the summer of 2005 as part of the vegetation mapping project. The points were randomly...

  18. #DDOD Use Case: Accuracy of healthcare.gov Plan Finder

    U.S. Department of Health & Human Services — SUMMARY DDOD use case to verify the accuracy of data obtained from the HealthCare Finder API after a user identified potential data quality issues. WHAT IS A USE...

  19. Accuracy of spinal navigation for Magerl-screws

    Herz, T

    2001-01-01

    Study design: assessment of the accuracy of frameless stereotactic navigation at the second cervical vertebra. Objectives: to assess the influence of the protocol of preoperative CT-scan and the registration technique on the accuracy of navigation for implanting Magerl-screws. Summary of background data: the use of navigation systems for implanting Magerl-screws could help to decrease the risk of complications and to reduce the required skin incision. Two parameters conceivably affecting the accuracy are the protocol of the preoperative CT-scan and the registration technique. Methods: four cervical spine segments of human cadavers were scanned with two different protocols (3 mm slice thickness/2 mm table increment, 1 mm slice thickness/1 mm table increment). Registration was performed either based on anatomical landmarks or using a specially designed percutaneous registration device. For the accuracy-check, the pointer tip was exactly placed on markers. The distance between the pointer and the marker displaye...

  20. A Novel Navigation Robustness and Accuracy Improvement System Project

    National Aeronautics and Space Administration — To address NASA's need for L1 C/A-based navigation with better anti-spoofing ability and higher accuracy, Broadata Communications, Inc. (BCI) proposes to develop a...

  1. Accuracy of depth of cut in micro milling operations

    Bissacco, Giuliano

    downscaling of conventional manufacturing technologies. Although in micro manufacturing operations particular precautions are taken, the ratio between tolerances and absolute dimensions increases. However, the absolute required accuracy for the functionality increases, therefore the absolute value of...

  2. Accuracy Assessment Points for Badlands National Park Vegetation Mapping Project

    National Park Service, Department of the Interior — This metadata is for the accuracy assessment data associated with the vegetation land cover and land use geospatial database for Badlands National Park and...

  3. Accuracy evaluation of pendulum gravity measurements of Robert von Sterneck

    Alena Pešková

    2015-06-01

    Full Text Available The accuracy of first pendulum gravity measurements in the Czech territory was determined using both original surveying notebooks of Robert Daublebsky von Sterneck and modern technologies. Since more accurate methods are used for gravity measurements nowadays, our work is mostly important from the historical point of view. In previous  works, the accuracy of Sterneck’s gravity measurements was determined using only a small dataset. Here we process all Sterneck’s measurements from the Czech territory (a dataset ten times larger than in the previous works, and we complexly assess the accuracy of these measurements. Locations of the measurements were found with the help of original notebooks. Gravity in the site was interpolated using actual gravity models. Finally, the accuracy of Sterneck’s measurements was evaluated as the difference between the measured and interpolated gravity.

  4. Accelerating scientific codes by performance and accuracy modeling

    Fabregat-Traver, Diego; Bientinesi, Paolo

    2016-01-01

    Scientific software is often driven by multiple parameters that affect both accuracy and performance. Since finding the optimal configuration of these parameters is a highly complex task, it extremely common that the software is used suboptimally. In a typical scenario, accuracy requirements are imposed, and attained through suboptimal performance. In this paper, we present a methodology for the automatic selection of parameters for simulation codes, and a corresponding prototype tool. To be amenable to our methodology, the target code must expose the parameters affecting accuracy and performance, and there must be formulas available for error bounds and computational complexity of the underlying methods. As a case study, we consider the particle-particle particle-mesh method (PPPM) from the LAMMPS suite for molecular dynamics, and use our tool to identify configurations of the input parameters that achieve a given accuracy in the shortest execution time. When compared with the configurations suggested by exp...

  5. Effective Analysis of Chinese Word-Segmentation Accuracy

    MA Weiyin

    2007-01-01

    Automatic word-segmentation is widely used in the ambiguity cancellation when processing large-scale real text,but during the process of unknown word detection in Chinese word segmentation,many detected word candidates are invalid.These false unknown word candidates deteriorate the overall segmentation accuracy,as it will affect the segmentation accuracy of known words.In this paper,we propose several methods for reducing the difficulties and improving the accuracy of the word-segmentation of written Chinese,such as full segmentation of a sentence,processing the duplicative word,idioms and statistical identification for unknown words.A simulation shows the feasibility of our proposed methods in improving the accuracy of word-segmentation of Chinese.

  6. Accuracy Assessment Points for Petersburg National Battlefield Vegetation Mapping Project

    National Park Service, Department of the Interior — This shapefile depicts the locations of thematic accuracy assessment sampling points used in the vegetation mapping of Petersburg National Battlefield. It was...

  7. Examination of the Accuracy of Coding Hospital-Acquired...

    U.S. Department of Health & Human Services — A new study, Examination of the Accuracy of Coding Hospital-Acquired Pressure Ulcer Stages, published in Volume 4, Issue 1 of the Medicare and Medicaid Research...

  8. 40 CFR 91.314 - Analyzer accuracy and specifications.

    2010-07-01

    ... deflection should generally not be used. (2) Some high resolution read-out systems, such as computers, data loggers, and so forth, can provide sufficient accuracy and resolution below 15 percent of full scale....

  9. Accuracy of analyses of microelectronics nanostructures in atom probe tomography

    Vurpillot, F.; Rolland, N.; Estivill, R.; Duguay, S.; Blavette, D.

    2016-07-01

    The routine use of atom probe tomography (APT) as a nano-analysis microscope in the semiconductor industry requires the precise evaluation of the metrological parameters of this instrument (spatial accuracy, spatial precision, composition accuracy or composition precision). The spatial accuracy of this microscope is evaluated in this paper in the analysis of planar structures such as high-k metal gate stacks. It is shown both experimentally and theoretically that the in-depth accuracy of reconstructed APT images is perturbed when analyzing this structure composed of an oxide layer of high electrical permittivity (higher-k dielectric constant) that separates the metal gate and the semiconductor channel of a field emitter transistor. Large differences in the evaporation field between these layers (resulting from large differences in material properties) are the main sources of image distortions. An analytic model is used to interpret inaccuracy in the depth reconstruction of these devices in APT.

  10. Accuracy Assessment Points for Colorado National Monument Vegetation Mapping Project

    National Park Service, Department of the Interior — This point file displays the 500 accuracy assessment (AA) points visited in July and August of 2004 as part of the vegetation mapping project. Five hundred and one...

  11. Accuracy Assessment Points for Wupatki National Monument Vegetation Mapping Project

    National Park Service, Department of the Interior — This spatial dataset in ESRI Coverage format maps accuracy assessment point locations for the vegetation map at Wupatki National Monument and in the surrounding...

  12. Error Estimation and Accuracy Improvements in Nodal Transport Methods

    The accuracy of the solutions produced by the Discrete Ordinates neutron transport nodal methods is analyzed.The obtained new numerical methodologies increase the accuracy of the analyzed scheems and give a POSTERIORI error estimators. The accuracy improvement is obtained with new equations that make the numerical procedure free of truncation errors and proposing spatial reconstructions of the angular fluxes that are more accurate than those used until present. An a POSTERIORI error estimator is rigurously obtained for one dimensional systems that, in certain type of problems, allows to quantify the accuracy of the solutions. From comparisons with the one dimensional results, an a POSTERIORI error estimator is also obtained for multidimensional systems. LOCAL indicators, which quantify the spatial distribution of the errors, are obtained by the decomposition of the menctioned estimators. This makes the proposed methodology suitable to perform adaptive calculations. Some numerical examples are presented to validate the theoretical developements and to illustrate the ranges where the proposed approximations are valid

  13. Accuracy Assessment of Coastal Topography Derived from Uav Images

    Long, N.; Millescamps, B.; Pouget, F.; Dumon, A.; Lachaussée, N.; Bertin, X.

    2016-06-01

    To monitor coastal environments, Unmanned Aerial Vehicle (UAV) is a low-cost and easy to use solution to enable data acquisition with high temporal frequency and spatial resolution. Compared to Light Detection And Ranging (LiDAR) or Terrestrial Laser Scanning (TLS), this solution produces Digital Surface Model (DSM) with a similar accuracy. To evaluate the DSM accuracy on a coastal environment, a campaign was carried out with a flying wing (eBee) combined with a digital camera. Using the Photoscan software and the photogrammetry process (Structure From Motion algorithm), a DSM and an orthomosaic were produced. Compared to GNSS surveys, the DSM accuracy is estimated. Two parameters are tested: the influence of the methodology (number and distribution of Ground Control Points, GCPs) and the influence of spatial image resolution (4.6 cm vs 2 cm). The results show that this solution is able to reproduce the topography of a coastal area with a high vertical accuracy (images is decreased.

  14. Parenting and adolescents' accuracy in perceiving parental values.

    Knafo, Ariel; Schwartz, Shalom H

    2003-01-01

    What determines adolescents' accuracy in perceiving parental values? The current study examined potential predictors including parental value communication, family value agreement, and parenting styles. In the study, 547 Israeli adolescents (aged 16 to 18) of diverse socioeconomic backgrounds participated with their parents. Adolescents reported the values they perceive their parents want them to hold. Parents reported their socialization values. Accuracy in perceiving parents' overall value system correlated positively with parents' actual and perceived value agreement and perceived parental warmth and responsiveness, but negatively with perceived value conflict, indifferent parenting, and autocratic parenting in all gender compositions of parent-child dyads. Other associations varied by dyad type. Findings were similar for predicting accuracy in perceiving two specific values: tradition and hedonism. The article discusses implications for the processes that underlie accurate perception, gender differences, and other potential influences on accuracy in value perception. PMID:12705575

  15. The symmetric BEM: bringing in more variables for better accuracy

    Clerc, Maureen; Gramfort, Alexandre; Olivi, Emmanuel; Papadopoulo, Théodore

    2010-01-01

    Electrophysiological modeling of Magneto- and Electro-encephalography (MEG and EEG) rely on accurate forward solvers that relate source activities to sensor measurements. In comparing a Boundary Element (BEM) and a Finite Element Method (FEM) for forward electroencephalography, in our early numerical experiments, we found the FEM to have a better accuracy than the BEM. This triggered a quest to improve the accuracy of Boundary Element Methods and led us to study the extended Green representat...

  16. Acquisition Accuracy Evaluation in Visual Inspection Systems - a Practical Approach

    Arsinte, Radu; Miron, Costin

    2008-01-01

    This paper draws a proposal of a set of parameters and methods for accuracy evaluation of visual inspection systems. The case of a monochrome board is treated, but practically all conclusions and methods may be extended for colour acquisition. Basically, the proposed parameters are grouped in five sets as follows:Internal noise;Video ADC cuantisation parameters;Analogue processing section parameters;Dominant frequencies;Synchronisation (lock-in) accuracy. On basis of this set of parameters wa...

  17. Method for Improving Indoor Positioning Accuracy Using Extended Kalman Filter

    Lee, Seoung-Hyeon; Lim, Il-Kwan; Lee, Jae-Kwang

    2016-01-01

    Beacons using bluetooth low-energy (BLE) technology have emerged as a new paradigm of indoor positioning service (IPS) because of their advantages such as low power consumption, miniaturization, wide signal range, and low cost. However, the beacon performance is poor in terms of the indoor positioning accuracy because of noise, motion, and fading, all of which are characteristics of a bluetooth signal and depend on the installation location. Therefore, it is necessary to improve the accuracy ...

  18. An RFID implementation in the automotive industry - improving inventory accuracy

    Hellström, Daniel; Wiberg, Mathias

    2010-01-01

    This paper explores and describes the impact of radio frequency identification (RFID) technology on inventory accuracy within a production and assembly plant, and proposes a model for assessing the impact of the technology on inventory accuracy. The empirical investigation, based on case study research, focuses on a RFID implementation at a supplier of bumper and spoiler systems to the automotive industry. The results indicate that RFID ensures that inventory inaccurac...

  19. Accuracy of gas analysis in lung function laboratories.

    Chinn, D.J.; Naruse, Y; Cotes, J E

    1986-01-01

    Fifty lung function laboratories in England and Wales analysed test gas mixtures of carbon monoxide and helium. Most of them also analysed mixtures of oxygen and carbon dioxide in nitrogen. The percentage accuracy of the results was within 1% of the expected value in only 14% of determinations of carbon monoxide concentration, 28% for carbon dioxide, 37% for helium, and 48% for oxygen. The accuracy of ratios of two concentrations of helium and carbon monoxide was better than that of the indiv...

  20. Determining factors for the accuracy of DMRG in chemistry.

    Keller, Sebastian F; Reiher, Markus

    2014-01-01

    The Density Matrix Renormalization Group (DMRG) algorithm has been a rising star for the accurate ab initio exploration of Born-Oppenheimer potential energy surfaces in theoretical chemistry. However, owing to its iterative numerical nature, pitfalls that can affect the accuracy of DMRG energies need to be circumvented. Here, after a brief introduction into this quantum chemical method, we discuss criteria that determine the accuracy of DMRG calculations. PMID:24983596

  1. Simulation efficiency and accuracy of different moisture transfer potentials

    Janssen, Hans

    2014-01-01

    Simulation models for moisture transfer in building materials are highly incongruent with respect to the moisture potential used. Often the relatively better numerical efficiency and accuracy of a certain moisture potential is put forward as motivation. Various claims are made in that respect, but factual evidence is typically lacking. This paper aims at providing such support by assessing simulation efficiency and accuracy for capillary pressure, relative humidity and -log(-capillary pressur...

  2. Speed accuracy trade-off under response deadlines

    Balcı, Fuat; Karşılar, Hakan; Simen, Patrick; Papadakis, Samantha

    2014-01-01

    Abstract The majority of two-alternative forced choice (2AFC) psychophysics studies have examined speed-accuracy trade-offs either in free-response or fixed viewing time paradigms with no hard time constraints on responding. Under response deadlines, reward maximization requires participants to modulate decision thresholds over the course of a trial such that when the deadline arrives a response is ensured despite the possible reduction of accuracy to the chance level. Importantly, this no...

  3. Improvement of Electrochemical Machining Accuracy by Using Dual Pole Tool

    2002-01-01

    Electrochemical machining (ECM) is one of the best al ternatives for producing complex shapes in advanced materials used in aircraft a nd aerospace industries. However, the reduction of the stray material removal co ntinues to be major challenges for industries in addressing accuracy improvement . This study presents a method of improving machining accuracy in ECM by using a dual pole tool with a metallic bush outside the insulated coating of a cathode tool. The bush is connected with anode and so the el...

  4. Accuracy of depth of cut in micro milling operations

    Bissacco, Giuliano

    2003-01-01

    In any kind of conventional machining operation, dimensional and geometrical accuracy of the machined part cannot be achieved without a precise control of cutting parameters as well as positioning accuracy. Miniaturization of components implies a reduction of all component’s dimensions and involves downscaling of conventional manufacturing technologies. Although in micro manufacturing operations particular precautions are taken, the ratio between tolerances and absolute dimensions increases. ...

  5. The correlation between accent perception accuracy and listening proficiency

    田方

    2012-01-01

    This study tries to examine the correlation between Chinese EFL learners' accent perception accuracy of and their lis- tening proficiency. Accent annotation data were collected from 80 English-majored freshmen and sophomores. Results show that their accent perception accuracy is positively related to their listening proficiency. Therefore, it is concluded that the teaching of the accent should be enhanced to help students overcome some supersegmental obstacles in their listening.

  6. The evaluation of singing voice accuracy: How tolerant are we?

    Larrouy, Pauline; Blanckaert, Ellen; Morsomme, Dominique

    2013-01-01

    The evaluation of the singing voice accuracy is partly based on the precision of the intervals between the tones of a sung performance. This study aims to observe the listeners’ tolerance when judging melodies in order to properly evaluate the singing voice accuracy in a melodic context For this purpose, an interval contained in familiar and unfamiliar sung performances was manipulated in two directions (compression and enlargement from 10 to 60 cents). This material was presented through ...

  7. Application Accuracy of Automatic Registration in Frameless Stereotaxy

    Rachinger, Jens; Keller, Boris von; Ganslandt, Oliver; Fahlbusch, Rudolf; Nimsky, Christopher

    2013-01-01

    Objective: We compared the application accuracy of an infrared- based neuronavigation system when used with a novel automatic registration with its application accuracy when standard fiducial-based registration is performed. Methods: The automatic referencing tool is based on markers that are integrated in the headrest holder we routinely use in our intraoperative magnetic resonance imaging (MRI) setting and can be detected by the navigation software automatically. For navigation targeting we...

  8. Distinguishing Fast and Slow Processes in Accuracy - Response Time Data.

    Coomans, Frederik; Hofman, Abe; Brinkhuis, Matthieu; van der Maas, Han L J; Maris, Gunter

    2016-01-01

    We investigate the relation between speed and accuracy within problem solving in its simplest non-trivial form. We consider tests with only two items and code the item responses in two binary variables: one indicating the response accuracy, and one indicating the response speed. Despite being a very basic setup, it enables us to study item pairs stemming from a broad range of domains such as basic arithmetic, first language learning, intelligence-related problems, and chess, with large numbers of observations for every pair of problems under consideration. We carry out a survey over a large number of such item pairs and compare three types of psychometric accuracy-response time models present in the literature: two 'one-process' models, the first of which models accuracy and response time as conditionally independent and the second of which models accuracy and response time as conditionally dependent, and a 'two-process' model which models accuracy contingent on response time. We find that the data clearly violates the restrictions imposed by both one-process models and requires additional complexity which is parsimoniously provided by the two-process model. We supplement our survey with an analysis of the erroneous responses for an example item pair and demonstrate that there are very significant differences between the types of errors in fast and slow responses. PMID:27167518

  9. Distinguishing Fast and Slow Processes in Accuracy - Response Time Data.

    Frederik Coomans

    Full Text Available We investigate the relation between speed and accuracy within problem solving in its simplest non-trivial form. We consider tests with only two items and code the item responses in two binary variables: one indicating the response accuracy, and one indicating the response speed. Despite being a very basic setup, it enables us to study item pairs stemming from a broad range of domains such as basic arithmetic, first language learning, intelligence-related problems, and chess, with large numbers of observations for every pair of problems under consideration. We carry out a survey over a large number of such item pairs and compare three types of psychometric accuracy-response time models present in the literature: two 'one-process' models, the first of which models accuracy and response time as conditionally independent and the second of which models accuracy and response time as conditionally dependent, and a 'two-process' model which models accuracy contingent on response time. We find that the data clearly violates the restrictions imposed by both one-process models and requires additional complexity which is parsimoniously provided by the two-process model. We supplement our survey with an analysis of the erroneous responses for an example item pair and demonstrate that there are very significant differences between the types of errors in fast and slow responses.

  10. Bayesian Estimation of Combined Accuracy for Tests with Verification Bias

    Lyle D. Broemeling

    2011-12-01

    Full Text Available This presentation will emphasize the estimation of the combined accuracy of two or more tests when verification bias is present. Verification bias occurs when some of the subjects are not subject to the gold standard. The approach is Bayesian where the estimation of test accuracy is based on the posterior distribution of the relevant parameter. Accuracy of two combined binary tests is estimated employing either “believe the positive” or “believe the negative” rule, then the true and false positive fractions for each rule are computed for two tests. In order to perform the analysis, the missing at random assumption is imposed, and an interesting example is provided by estimating the combined accuracy of CT and MRI to diagnose lung cancer. The Bayesian approach is extended to two ordinal tests when verification bias is present, and the accuracy of the combined tests is based on the ROC area of the risk function. An example involving mammography with two readers with extreme verification bias illustrates the estimation of the combined test accuracy for ordinal tests.

  11. Accuracy of GIPSY PPP from a denser network

    Gokhan Hayal, Adem; Ugur Sanli, Dogan

    2015-04-01

    Researchers need to know about the accuracy of GPS for the planning of their field survey and hence to obtain reliable positions as well as deformation rates. Geophysical applications such as monitoring of development of a fault creep or of crustal motion for global sea level rise studies necessitate the use of continuous GPS whereas applications such as determining co-seismic displacements where permanent GPS sites are sparsely scattered require the employment of episodic campaigns. Recently, real time applications of GPS in relation to the early prediction of earthquakes and tsunamis are in concern. Studying the static positioning accuracy of GPS has been of interest to researchers for more than a decade now. Various software packages and modeling strategies have been tested so far. Relative positioning accuracy was compared with PPP accuracy. For relative positioning, observing session duration and network geometry of reference stations appear to be the dominant factors on GPS accuracy whereas observing session duration seems to be the only factor influencing the PPP accuracy. We believe that latest developments concerning the accuracy of static GPS from well-established software will form a basis for the quality of GPS field works mentioned above especially for real time applications which are referred to more frequently nowadays. To assess the GPS accuracy, conventionally some 10 to 30 regionally or globally scattered networks of GPS stations are used. In this study, we enlarge the size of GPS network up to 70 globally scattered IGS stations to observe the changes on our previous accuracy modeling which employed only 13 stations. We use the latest version 6.3 of GIPSY/OASIS II software and download the data from SOPAC archives. Noting the effect of the ionosphere on our previous accuracy modeling, here we selected the GPS days through which the k-index values are lower than 4. This enabled us to extend the interval of observing session duration used for the

  12. Accuracy of magnetic resonance in identifying traumatic intraarticular knee lesions

    Vaz Carlos Eduardo Sanches

    2005-01-01

    Full Text Available PURPOSE: To evaluate the diagnostic accuracy of magnetic resonance imaging of the knee in identifying traumatic intraarticular knee lesions. METHOD: 300 patients with a clinical diagnosis of traumatic intraarticular knee lesions underwent prearthoscopic magnetic resonance imaging. The sensitivity, specificity, positive predictive value, negative predictive value, likelihood ratio for a positive test, likelihood ratio for a negative test, and accuracy of magnetic resonance imaging were calculated relative to the findings during arthroscopy in the studied structures of the knee (medial meniscus, lateral meniscus, anterior cruciate ligament, posterior cruciate ligament, and articular cartilage. RESULTS: Magnetic resonance imaging produced the following results regarding detection of lesions: medial meniscus: sensitivity 97.5%, specificity 92.9%, positive predictive value 93.9%, positive negative value 97%, likelihood positive ratio 13.7, likelihood negative ratio 0.02, and accuracy 95.3%; lateral meniscus: sensitivity 91.9%, specificity 93.6%, positive predictive value 92.7%, positive negative value 92.9%, likelihood positive ratio 14.3, likelihood negative ratio 0.08, and accuracy 93.6%; anterior cruciate ligament: sensitivity 99.0%, specificity 95.9%, positive predictive value 91.9%, positive negative value 99.5%, likelihood positive ratio 21.5, likelihood negative ratio 0.01, and accuracy 96.6%; posterior cruciate ligament: sensitivity 100%, specificity 99%, positive predictive value 80.0%, positive negative value 100%, likelihood positive ratio 100, likelihood negative ratio 0.01, and accuracy 99.6%; articular cartilage: sensitivity 76.1%, specificity 94.9%, positive predictive value 94.7%, positive negative value 76.9%, likelihood positive ratio 14.9, likelihood negative ratio 0.25, and accuracy 84.6%. CONCLUSION: Magnetic resonance imaging is a satisfactory diagnostic tool for evaluating meniscal and ligamentous lesions of the knee, but it is

  13. Accuracy evaluation of 3D lidar data from small UAV

    Tulldahl, H. M.; Bissmarck, Fredrik; Larsson, Hâkan; Grönwall, Christina; Tolt, Gustav

    2015-10-01

    A UAV (Unmanned Aerial Vehicle) with an integrated lidar can be an efficient system for collection of high-resolution and accurate three-dimensional (3D) data. In this paper we evaluate the accuracy of a system consisting of a lidar sensor on a small UAV. High geometric accuracy in the produced point cloud is a fundamental qualification for detection and recognition of objects in a single-flight dataset as well as for change detection using two or several data collections over the same scene. Our work presented here has two purposes: first to relate the point cloud accuracy to data processing parameters and second, to examine the influence on accuracy from the UAV platform parameters. In our work, the accuracy is numerically quantified as local surface smoothness on planar surfaces, and as distance and relative height accuracy using data from a terrestrial laser scanner as reference. The UAV lidar system used is the Velodyne HDL-32E lidar on a multirotor UAV with a total weight of 7 kg. For processing of data into a geographically referenced point cloud, positioning and orientation of the lidar sensor is based on inertial navigation system (INS) data combined with lidar data. The combination of INS and lidar data is achieved in a dynamic calibration process that minimizes the navigation errors in six degrees of freedom, namely the errors of the absolute position (x, y, z) and the orientation (pitch, roll, yaw) measured by GPS/INS. Our results show that low-cost and light-weight MEMS based (microelectromechanical systems) INS equipment with a dynamic calibration process can obtain significantly improved accuracy compared to processing based solely on INS data.

  14. Accuracy analysis and design of A3 parallel spindle head

    Ni, Yanbing; Zhang, Biao; Sun, Yupeng; Zhang, Yuan

    2016-03-01

    As functional components of machine tools, parallel mechanisms are widely used in high efficiency machining of aviation components, and accuracy is one of the critical technical indexes. Lots of researchers have focused on the accuracy problem of parallel mechanisms, but in terms of controlling the errors and improving the accuracy in the stage of design and manufacturing, further efforts are required. Aiming at the accuracy design of a 3-DOF parallel spindle head(A3 head), its error model, sensitivity analysis and tolerance allocation are investigated. Based on the inverse kinematic analysis, the error model of A3 head is established by using the first-order perturbation theory and vector chain method. According to the mapping property of motion and constraint Jacobian matrix, the compensatable and uncompensatable error sources which affect the accuracy in the end-effector are separated. Furthermore, sensitivity analysis is performed on the uncompensatable error sources. The sensitivity probabilistic model is established and the global sensitivity index is proposed to analyze the influence of the uncompensatable error sources on the accuracy in the end-effector of the mechanism. The results show that orientation error sources have bigger effect on the accuracy in the end-effector. Based upon the sensitivity analysis results, the tolerance design is converted into the issue of nonlinearly constrained optimization with the manufacturing cost minimum being the optimization objective. By utilizing the genetic algorithm, the allocation of the tolerances on each component is finally determined. According to the tolerance allocation results, the tolerance ranges of ten kinds of geometric error sources are obtained. These research achievements can provide fundamental guidelines for component manufacturing and assembly of this kind of parallel mechanisms.

  15. Accuracy of a wireless localization system for radiotherapy

    Purpose: A system has been developed for patient positioning based on real-time localization of implanted electromagnetic transponders (beacons). This study demonstrated the accuracy of the system before clinical trials. Methods and materials: We describe the overall system. The localization component consists of beacons and a source array. A rigid phantom was constructed to place the beacons at known offsets from a localization array. Tests were performed at distances of 80 and 270 mm from the array and at positions in the array plane of up to 8 cm offset. Tests were performed in air and saline to assess the effect of tissue conductivity and with multiple transponders to evaluate crosstalk. Tracking was tested using a dynamic phantom creating a circular path at varying speeds. Results: Submillimeter accuracy was maintained throughout all experiments. Precision was greater proximal to the source plane (σx = 0.006 mm, σy = 0.01 mm, σz = 0.006 mm), but continued to be submillimeter at the end of the designed tracking range at 270 mm from the array (σx = 0.27 mm, σy = 0.36 mm, σz = 0.48 mm). The introduction of saline and the use of multiple beacons did not affect accuracy. Submillimeter accuracy was maintained using the dynamic phantom at speeds of up to 3 cm/s. Conclusion: This system has demonstrated the accuracy needed for localization and monitoring of position during treatment

  16. EVALUATING PARAMETERS AFFECTING THE GEOREFERENCING ACCURACY OF TERRESTRIAL LASER SCANNERS

    M. Miri

    2012-09-01

    Full Text Available Today laser scanning is used as a powerful technology in measuring various simple and complex objects in cultural heritage applications. Depending on the size and the complexity of the objects, these measurements are usually made from several stations. Similar to all other surveying techniques, the coordinate systems of such measurements need to be registered. For this, a number of retro-reflective targets visible from different stations are used. In practice, the target centres are entered in the computations. The accuracy of the target centres, therefore, need to be high or the final object coordinates might not be of sufficient accuracy. A number of factors including the distance between a target and the laser scanner, the direction of the target surface with respect to the laser scanner beams, the intensity and the number of reflected laser beams affect the accuracy of target centres. In this paper, various tests are carried out to examine the effect of such factors on the accuracy of coordinates obtained for the target centres. The results show that the distance to the laser scanner and the angle between a target surface and the corresponding laser beams have considerable effects on the locational accuracy of the targets.

  17. Diagnostic Accuracy of Procalcitonin in Bacterial Meningitis Versus Nonbacterial Meningitis

    Wei, Ting-Ting; Hu, Zhi-De; Qin, Bao-Dong; Ma, Ning; Tang, Qing-Qin; Wang, Li-Li; Zhou, Lin; Zhong, Ren-Qian

    2016-01-01

    Abstract Several studies have investigated the diagnostic accuracy of procalcitonin (PCT) levels in blood or cerebrospinal fluid (CSF) in bacterial meningitis (BM), but the results were heterogeneous. The aim of the present study was to ascertain the diagnostic accuracy of PCT as a marker for BM detection. A systematic search of the EMBASE, Scopus, Web of Science, and PubMed databases was performed to identify studies published before December 7, 2015 investigating the diagnostic accuracy of PCT for BM. The quality of the eligible studies was assessed using the revised Quality Assessment for Studies of Diagnostic Accuracy method. The overall diagnostic accuracy of PCT detection in CSF or blood was pooled using the bivariate model. Twenty-two studies involving 2058 subjects were included in this systematic review and meta-analysis. The overall specificities and sensitivities were 0.86 and 0.80 for CSF PCT, and 0.97 and 0.95 for blood PCT, respectively. Areas under the summary receiver operating characteristic curves were 0.90 and 0.98 for CSF PCT and blood PCT, respectively. The major limitation of this systematic review and meta-analysis was the small number of studies included and the heterogeneous diagnostic thresholds adopted by eligible studies. Our meta-analysis shows that PCT is a useful biomarker for BM diagnosis. PMID:26986140

  18. Accuracy of needle position measurements using fiber Bragg gratings.

    Henken, Kirsten; Van Gerwen, Dennis; Dankelman, Jenny; Van Den Dobbelsteen, John

    2012-11-01

    Accurate placement of the needle tip is essential in percutaneous therapies such as radiofrequency ablation (RFA) of liver tumors. Use of a robotic system for navigating the needle could improve the targeting accuracy. Real-time information on the needle tip position is needed, since a needle deflects during insertion in tissue. Needle shape can be reconstructed based on strain measurements within the needle. In the current experiment we determined the accuracy with which the needle tip position can be derived from strain measurements using Fiber Bragg Gratings (FBGs). Three glass fibers equipped with two FBGs each were incorporated in a needle. The needle was clamped at one end and deformed by applying static radial displacements at one or two locations. The FBG output was used for offline estimation of the needle shape and tip position. During deflections of the needle tip up to 12.5 mm, the tip position was estimated with a mean accuracy of 0.89 mm (std 0.42 mm). Adding a second deflection resulted in an error of 1.32 mm (std 0.48 mm). This accuracy is appropriate for applications such as RFA of liver tumors. The results further show that the accuracy can be improved by optimizing the placement of FBGs. PMID:22455615

  19. Evidence for Enhanced Interoceptive Accuracy in Professional Musicians

    Schirmer-Mokwa, Katharina L.; Fard, Pouyan R.; Zamorano, Anna M.; Finkel, Sebastian; Birbaumer, Niels; Kleber, Boris A.

    2015-01-01

    Interoception is defined as the perceptual activity involved in the processing of internal bodily signals. While the ability of internal perception is considered a relatively stable trait, recent data suggest that learning to integrate multisensory information can modulate it. Making music is a uniquely rich multisensory experience that has shown to alter motor, sensory, and multimodal representations in the brain of musicians. We hypothesize that musical training also heightens interoceptive accuracy comparable to other perceptual modalities. Thirteen professional singers, twelve string players, and thirteen matched non-musicians were examined using a well-established heartbeat discrimination paradigm complemented by self-reported dispositional traits. Results revealed that both groups of musicians displayed higher interoceptive accuracy than non-musicians, whereas no differences were found between singers and string-players. Regression analyses showed that accumulated musical practice explained about 49% variation in heartbeat perception accuracy in singers but not in string-players. Psychometric data yielded a number of psychologically plausible inter-correlations in musicians related to performance anxiety. However, dispositional traits were not a confounding factor on heartbeat discrimination accuracy. Together, these data provide first evidence indicating that professional musicians show enhanced interoceptive accuracy compared to non-musicians. We argue that musical training largely accounted for this effect. PMID:26733836

  20. Evidence for enhanced interoceptive accuracy in professional musicians

    Katharina eSchirmer-Mokwa

    2015-12-01

    Full Text Available Interoception is defined as the perceptual activity involved in the processing of internal bodily signals. While the ability of internal perception is considered a relatively stable trait, recent data suggest that learning to integrate multisensory information can modulate it. Making music is a uniquely rich multisensory experience that has shown to alter motor, sensory, and multimodal representations in the brain of musicians. We hypothesize that musical training also heightens interoceptive accuracy comparable to other perceptual modalities. Thirteen professional singers, twelve string players, and thirteen matched non-musicians were examined using a well-established heartbeat discrimination paradigm complemented by self-reported dispositional traits. Results revealed that both groups of musicians displayed higher interoceptive accuracy than non-musicians, whereas no differences were found between singers and string-players. Regression analyses showed that accumulated musical practice explained about 49% variation in heartbeat perception accuracy in singers but not in string-players. Psychometric data yielded a number of psychologically plausible inter-correlations in musicians related to performance anxiety. However, dispositional traits were not a confounding factor on heartbeat discrimination accuracy. Together, these data provide first evidence indicating that professional musicians show enhanced interoceptive accuracy compared to non-musicians. We argue that musical training largely accounted for this effect.

  1. Evidence for Enhanced Interoceptive Accuracy in Professional Musicians.

    Schirmer-Mokwa, Katharina L; Fard, Pouyan R; Zamorano, Anna M; Finkel, Sebastian; Birbaumer, Niels; Kleber, Boris A

    2015-01-01

    Interoception is defined as the perceptual activity involved in the processing of internal bodily signals. While the ability of internal perception is considered a relatively stable trait, recent data suggest that learning to integrate multisensory information can modulate it. Making music is a uniquely rich multisensory experience that has shown to alter motor, sensory, and multimodal representations in the brain of musicians. We hypothesize that musical training also heightens interoceptive accuracy comparable to other perceptual modalities. Thirteen professional singers, twelve string players, and thirteen matched non-musicians were examined using a well-established heartbeat discrimination paradigm complemented by self-reported dispositional traits. Results revealed that both groups of musicians displayed higher interoceptive accuracy than non-musicians, whereas no differences were found between singers and string-players. Regression analyses showed that accumulated musical practice explained about 49% variation in heartbeat perception accuracy in singers but not in string-players. Psychometric data yielded a number of psychologically plausible inter-correlations in musicians related to performance anxiety. However, dispositional traits were not a confounding factor on heartbeat discrimination accuracy. Together, these data provide first evidence indicating that professional musicians show enhanced interoceptive accuracy compared to non-musicians. We argue that musical training largely accounted for this effect. PMID:26733836

  2. Accuracy of rainfall measurement for scales of hydrological interest

    S. J. Wood

    2000-01-01

    Full Text Available The dense network of 49 raingauges over the 135 km2 Brue catchment in Somerset, England is used to examine the accuracy of rainfall estimates obtained from raingauges and from weather radar. Methods for data quality control and classification of precipitation types are first described. A super-dense network comprising eight gauges within a 2 km grid square is employed to obtain a 'true value' of rainfall against which the 2 km radar grid and a single 'typical gauge' estimate can be compared. Accuracy is assessed as a function of rainfall intensity, for different periods of time-integration (15 minutes, 1 hour and 1 day and for two 8-gauge networks in areas of low and high relief. In a similar way, the catchment gauge network is used to provide the 'true catchment rainfall' and the accuracy of a radar estimate (an area-weighted average of radar pixel values and a single 'typical gauge' estimate of catchment rainfall evaluated as a function of rainfall intensity. A single gauge gives a standard error of estimate for rainfall in a 2 km square and over the catchment of 33% and 65% respectively, at rain rates of 4 mm in 15 minutes. Radar data at 2 km resolution give corresponding errors of 50% and 55%. This illustrates the benefit of using radar when estimating catchment scale rainfall. A companion paper (Wood et al., 2000 considers the accuracy of rainfall estimates obtained using raingauge and radar in combination. Keywords: rainfall, accuracy, raingauge, radar

  3. Accuracy of Loopy belief propagation in Gaussian models.

    Nishiyama, Yu; Watanabe, Sumio

    2009-05-01

    This paper considers the loopy belief propagation (LBP) algorithm applied to Gaussian graphical models. It is known for Gaussian belief propagation that, if LBP converges, LBP computes the exact posterior means but incorrect variances. In this paper, we analytically derive the posterior variances for some special structured graphs and clarify the accuracy of LBP. For the graphs of a single cycle, we derive a rigorous solution for the posterior variances and thereby find the quantity that determines the accuracy of LBP. Based on this result, we state a necessary condition for LBP convergence. The quantity above also plays an important role in graphs of a single cycle with arbitrary trees. For arbitrary topological graphs, we consider the situation where correlations between any pair of nodes are comparatively small and show analytically the principal values that determine the accuracy of LBP. PMID:19243911

  4. THE ACCURACY OF GENERAL GOVERNMENT BALANCE FORECASTS IN ROMANIA

    Mihaela SIMIONESCU

    2015-03-01

    Full Text Available Economic forecasts are an essential building block for a budgetary anticipation in order to determine the budgetary objectives and to sustain the tax and expenditure plans. In Romania the surveillance process is ensured by the use of budget programs. The aim of this paper is to improve the budgetary planning by recommending the use of the forecasted general budget balance provided by the institution with the highest accuracy during the crisis (2008-2013. More types of projections were analyzed during the recent economic crisis and the IMF forecasts for this indicator outperformed those provided by Dobrescu model and the European Union. Therefore, the recommendation is related to the use of IMF predictions in establishing the next budgetary plan for 2014 and 2015. Moreover, this research also brings improvements in the methodological framework, by proposing some aggregated accuracy indicators (S1, S2, S3 and S measures for solving the problem of contradictory results of different accuracy indicators.

  5. Geometric accuracy of wax bade models manufactured in silicon moulds

    G. Budzik

    2010-01-01

    Full Text Available The article presents the test results of the geometric accuracy of wax blade models manufactured in silicon moulds in the Rapid Tooling process, with the application of the Vacuum Casting technology. In batch production casting waxes are designed for the manufacture of models and components of model sets through injection into a metal die. The objective of the tests was to determine the possibility of using traditional wax for the production of casting models in the rapid prototyping process. Blade models made of five types of casting wax were measured. The definition of the geometric accuracy of wax blade models makes it possible to introduce individual modifications aimed at improving their shape in order to increase the dimensional accuracy of blade models manufactured in the rapid prototyping process.

  6. Required accuracy and dose thresholds in individual monitoring

    Christensen, P.; Griffith, R.V.

    1994-01-01

    The paper follows the approach given in recent revisions of CEC and IAEA recommendations on requirements in individual monitoring for external radiations. The ICRP requirements on overall accuracy for individual monitoring, as given in ICRP Publication 35 (1982), form the basis for the...... specification of detailed accuracy requirements which are needed in practical routine monitoring. The ICRP overall accuracy requirement is defined as an allowable maximum uncertainty factor at the 95% confidence level for a single measurement of the relevant dose quantity, i.e. H(p)(10) and H(p)(0.07). From...... this uncertainty factor, a value of 21% can be evaluated for the allowable maximum overall standard deviation for dose measurements at dose levels near the annual dose limits increasing to 45% for dose levels at the lower end of the dose range required to be monitored. A method is described for...

  7. Accuracy of reactivity predictions for the MARIA reactor

    The high flux water cooled, beryllium moderated reactor MARIA at the Institute of Atomic Energy in Poland is used mainly as a source of neutrons for neutronography, solid state physics and for irradiation of isotopes and materials. Introduction of new fuel is planned, which makes particularly important the accuracy of computational reactivity predictions. The complicated geometry of the MARIA reactor core makes the problem of accuracy difficult to solve. The prerequisite of MARIA reactivity calculations is the determination of the quantities of He-3 and Li-6 for each beryllium block. Authors have discussed this aspect at Kranjska Gora 2002. In the present paper accuracy obtained with different core model simplifications is discussed. The codes REBUS, TRITAC and MCNP have been used for that purpose. The results of computations are compared with measurement on two critical assemblies. The computational scheme has been used to calculate reactivity effect of the new fuel. (author)

  8. Follow your breath: respiratory interoceptive accuracy in experienced meditators.

    Daubenmier, Jennifer; Sze, Jocelyn; Kerr, Catherine E; Kemeny, Margaret E; Mehling, Wolf

    2013-08-01

    Attention to internal bodily sensations is a core feature of mindfulness meditation. Previous studies have not detected differences in interoceptive accuracy between meditators and nonmeditators on heartbeat detection and perception tasks. We compared differences in respiratory interoceptive accuracy between meditators and nonmeditators in the ability to detect and discriminate respiratory resistive loads and sustain accurate perception of respiratory tidal volume during nondistracted and distracted conditions. Groups did not differ in overall performance on the detection and discrimination tasks; however, meditators were more accurate in discriminating the resistive load with the lowest ceiling effect. Meditators were also more accurate during the nondistracted tracking task at a lag time of 1 s following the breath. Results provide initial support for the notion that meditators have greater respiratory interoceptive accuracy compared to nonmeditators. PMID:23692525

  9. Classification accuracy analyses using Shannon’s Entropy

    Shashi Poonam Indwar

    2014-11-01

    Full Text Available There are many methods for determining the Classification Accuracy. In this paper significance of Entropy of training signatures in Classification has been shown. Entropy of training signatures of the raw digital image represents the heterogeneity of the brightness values of the pixels in different bands. This implies that an image comprising a homogeneous lu/lc category will be associated with nearly the same reflectance values that would result in the occurrence of a very low entropy value. On the other hand an image characterized by the occurrence of diverse lu/lc categories will consist of largely differing reflectance values due to which the entropy of such image would be relatively high. This concept leads to analyses of classification accuracy. Although Entropy has been used many times in RS and GIS but its use in determination of classification accuracy is new approach.

  10. The predictive accuracy of intertemporal-choice models.

    Arfer, Kodi B; Luhmann, Christian C

    2015-05-01

    How do people choose between a smaller reward available sooner and a larger reward available later? Past research has evaluated models of intertemporal choice by measuring goodness of fit or identifying which decision-making anomalies they can accommodate. An alternative criterion for model quality, which is partly antithetical to these standard criteria, is predictive accuracy. We used cross-validation to examine how well 10 models of intertemporal choice could predict behaviour in a 100-trial binary-decision task. Many models achieved the apparent ceiling of 85% accuracy, even with smaller training sets. When noise was added to the training set, however, a simple logistic-regression model we call the difference model performed particularly well. In many situations, between-model differences in predictive accuracy may be small, contrary to long-standing controversy over the modelling question in research on intertemporal choice, but the simplicity and robustness of the difference model recommend it to future use. PMID:25773127

  11. Do Shared Interests Affect the Accuracy of Budgets?

    Ilse Maria Beuren

    2015-04-01

    Full Text Available The creation of budgetary slack is a phenomenon associated with various behavioral aspects. This study focuses on accuracy in budgeting when the benefit of the slack is shared between the unit manager and his/her assistant. In this study, accuracy is measured by the level of slack in the budget, and the benefit of slack represents a financial consideration for the manager and the assistant. The study aims to test how shared interests in budgetary slack affect the accuracy of budget reports in an organization. To this end, an experimental study was conducted with a sample of 90 employees in management and other leadership positions at a cooperative that has a variable compensation plan based on the achievement of organizational goals. The experiment conducted in this study is consubstantiated by the study of Church, Hannan and Kuang (2012, which was conducted with a sample of undergraduate students in the United States and used a quantitative approach to analyze the results. In the first part of the experiment, the results show that when budgetary slack is not shared, managers tend to create greater slack when the assistant is not aware of the creation of slack; these managers thus generate a lower accuracy index than managers whose assistants are aware of the creation of slack. When budgetary slack is shared, there is higher average slack when the assistant is aware of the creation of slack. In the second part of the experiment, the accuracy index is higher for managers who prepare the budget with the knowledge that their assistants prefer larger slack values. However, the accuracy level differs between managers who know that their assistants prefer maximizing slack values and managers who do not know their assistants' preference regarding slack. These results contribute to the literature by presenting evidence of managers' behavior in the creation of budgetary slack in scenarios in which they share the benefits of slack with their assistants.

  12. Contributions of speed and accuracy to translational selection in bacteria.

    Wenqi Ran

    Full Text Available Among bacteria, we have previously shown that species that are capable of rapid growth have stronger selection on codon usage than slow growing species, and possess higher numbers of rRNA and tRNA genes. This suggests that fast-growers are adapted for fast protein synthesis. There is also considerable evidence that codon usage is influenced by accuracy of translation, and some authors have argued that accuracy is more important than speed. Here we compare the strength of the two effects by studying the codon usages in high and low expression genes and on conserved and variable sites within high expression genes. We introduce a simple statistical method that can be used to assess the significance and the strength of the two types of bias in the same sets of sequences. We compare our statistical measure of codon bias to the common used codon adaptation index, and show that the new measure is preferable for three reasons for the purposes of this analysis. Across a large sample of bacterial genomes, both effects from speed and accuracy are clearly visible, although the speed effect appears to be much stronger than the accuracy effect and is found to be significant in a larger proportion of genomes. It is also difficult to explain the correlation of codon bias in the high expression genes with growth rates and numbers of copies of tRNA and rRNA genes on the basis of selection for accuracy. Hence we conclude that selection for translational speed is a dominant effect in driving codon usage bias in fast-growing bacteria, with selection for accuracy playing a small supplementary role.

  13. Accuracy and Consistency of Respiratory Gating in Abdominal Cancer Patients

    Purpose: To evaluate respiratory gating accuracy and intrafractional consistency for abdominal cancer patients treated with respiratory gated treatment on a regular linear accelerator system. Methods and Materials: Twelve abdominal patients implanted with fiducials were treated with amplitude-based respiratory-gated radiation therapy. On the basis of daily orthogonal fluoroscopy, the operator readjusted the couch position and gating window such that the fiducial was within a setup margin (fiducial-planning target volume [f-PTV]) when RPM indicated “beam-ON.” Fifty-five pre- and post-treatment fluoroscopic movie pairs with synchronized respiratory gating signal were recorded. Fiducial motion traces were extracted from the fluoroscopic movies using a template matching algorithm and correlated with f-PTV by registering the digitally reconstructed radiographs with the fluoroscopic movies. Treatment was determined to be “accurate” if 50% of the fiducial area stayed within f-PTV while beam-ON. For movie pairs that lost gating accuracy, a MATLAB program was used to assess whether the gating window was optimized, the external-internal correlation (EIC) changed, or the patient moved between movies. A series of safety margins from 0.5 mm to 3 mm was added to f-PTV for reassessing gating accuracy. Results: A decrease in gating accuracy was observed in 44% of movie pairs from daily fluoroscopic movies of 12 abdominal patients. Three main causes for inaccurate gating were identified as change of global EIC over time (∼43%), suboptimal gating setup (∼37%), and imperfect EIC within movie (∼13%). Conclusions: Inconsistent respiratory gating accuracy may occur within 1 treatment session even with a daily adjusted gating window. To improve or maintain gating accuracy during treatment, we suggest using at least a 2.5-mm safety margin to account for gating and setup uncertainties

  14. Evaluation of radiographers’ mammography screen-reading accuracy in Australia

    Debono, Josephine C, E-mail: josephine.debono@bci.org.au [Westmead Breast Cancer Institute, Westmead, New South Wales (Australia); Poulos, Ann E [Discipline of Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, Lidcombe, New South Wales (Australia); Houssami, Nehmat [Screening and Test Evaluation Program, School of Public Health (A27), Sydney Medical School, University of Sydney, Sydney, New South Wales (Australia); Turner, Robin M [School of Public Health and Community Medicine, University of New South Wales, Sydney, New South Wales (Australia); Boyages, John [Macquarie University Cancer Institute, Macquarie University Hospital, Australian School of Advanced Medicine, Macquarie University, Sydney, New South Wales (Australia); Westmead Breast Cancer Institute, Westmead, New South Wales (Australia)

    2015-03-15

    This study aimed to evaluate the accuracy of radiographers’ screen-reading mammograms. Currently, radiologist workforce shortages may be compromising the BreastScreen Australia screening program goal to detect early breast cancer. The solution to a similar problem in the United Kingdom has successfully encouraged radiographers to take on the role as one of two screen-readers. Prior to consideration of this strategy in Australia, educational and experiential differences between radiographers in the United Kingdom and Australia emphasise the need for an investigation of Australian radiographers’ screen-reading accuracy. Ten radiographers employed by the Westmead Breast Cancer Institute with a range of radiographic (median = 28 years), mammographic (median = 13 years) and BreastScreen (median = 8 years) experience were recruited to blindly and independently screen-read an image test set of 500 mammograms, without formal training. The radiographers indicated the presence of an abnormality using BI-RADS®. Accuracy was determined by comparison with the gold standard of known outcomes of pathology results, interval matching and client 6-year follow-up. Individual sensitivity and specificity levels ranged between 76.0% and 92.0%, and 74.8% and 96.2% respectively. Pooled screen-reader accuracy across the radiographers estimated sensitivity as 82.2% and specificity as 89.5%. Areas under the reading operating characteristic curve ranged between 0.842 and 0.923. This sample of radiographers in an Australian setting have adequate accuracy levels when screen-reading mammograms. It is expected that with formal screen-reading training, accuracy levels will improve, and with support, radiographers have the potential to be one of the two screen-readers in the BreastScreen Australia program, contributing to timeliness and improved program outcomes.

  15. Achieving seventh-order amplitude accuracy in leapfrog integrations

    Williams, Paul

    2015-04-01

    The leapfrog time-stepping scheme is commonly used in general circulation models of weather and climate. The Robert-Asselin filter is used in conjunction with it, to damp the computational mode. Although the leapfrog scheme makes no amplitude errors when integrating linear oscillations, the Robert-Asselin filter introduces first-order amplitude errors. The RAW filter, which was recently proposed as an improvement, eliminates the first-order amplitude errors and yields third-order amplitude accuracy. This development has been shown to significantly increase the skill of medium-range weather forecasts. However, it has not previously been shown how to further improve the accuracy by eliminating the third- and higher-order amplitude errors. This presentation will show that leapfrogging over a suitably weighted blend of the filtered and unfiltered tendencies eliminates the third-order amplitude errors and yields fifth-order amplitude accuracy. It will also show that the use of a more discriminating (1,-4,6,-4,1) filter instead of a (1,-2,1) filter eliminates the fifth-order amplitude errors and yields seventh-order amplitude accuracy. Other related schemes are obtained by varying the values of the filter parameters, and it is found that several combinations offer an appealing compromise of stability and accuracy. The proposed new schemes are shown to yield substantial forecast improvements in a medium-complexity atmospheric general circulation model. They appear to be attractive alternatives to the filtered leapfrog schemes currently used in many weather and climate models. Reference Williams PD (2013) Achieving seventh-order amplitude accuracy in leapfrog integrations. Monthly Weather Review 141(9), pp 3037-3051. DOI: 10.1175/MWR-D-12-00303.1

  16. Evaluation of radiographers’ mammography screen-reading accuracy in Australia

    This study aimed to evaluate the accuracy of radiographers’ screen-reading mammograms. Currently, radiologist workforce shortages may be compromising the BreastScreen Australia screening program goal to detect early breast cancer. The solution to a similar problem in the United Kingdom has successfully encouraged radiographers to take on the role as one of two screen-readers. Prior to consideration of this strategy in Australia, educational and experiential differences between radiographers in the United Kingdom and Australia emphasise the need for an investigation of Australian radiographers’ screen-reading accuracy. Ten radiographers employed by the Westmead Breast Cancer Institute with a range of radiographic (median = 28 years), mammographic (median = 13 years) and BreastScreen (median = 8 years) experience were recruited to blindly and independently screen-read an image test set of 500 mammograms, without formal training. The radiographers indicated the presence of an abnormality using BI-RADS®. Accuracy was determined by comparison with the gold standard of known outcomes of pathology results, interval matching and client 6-year follow-up. Individual sensitivity and specificity levels ranged between 76.0% and 92.0%, and 74.8% and 96.2% respectively. Pooled screen-reader accuracy across the radiographers estimated sensitivity as 82.2% and specificity as 89.5%. Areas under the reading operating characteristic curve ranged between 0.842 and 0.923. This sample of radiographers in an Australian setting have adequate accuracy levels when screen-reading mammograms. It is expected that with formal screen-reading training, accuracy levels will improve, and with support, radiographers have the potential to be one of the two screen-readers in the BreastScreen Australia program, contributing to timeliness and improved program outcomes

  17. Accuracy of helium accumulation fluence monitor for fast reactor dosimetry

    Ito, Chikara; Aoyama, Takafumi [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1998-03-01

    A helium (He) accumulation fluence monitor (HAFM) has been developed for fast reactor dosimetry. In order to evaluate the measurement accuracy of neutron fluence by the HAFM method, the HAFMs of enriched boron (B) and beryllium (Be) were irradiated in the Fast Neutron Source Reactor `YAYOI`. The number of He atoms produced in the HAFMs were measured and compared with the calculated values. As a result of this study, it was confirmed that the neutron fluence could be measured within 5 % by the HAFM method, and that met the required accuracy for fast reactor dosimetry. (author)

  18. Measurement system with high accuracy for laser beam quality.

    Ke, Yi; Zeng, Ciling; Xie, Peiyuan; Jiang, Qingshan; Liang, Ke; Yang, Zhenyu; Zhao, Ming

    2015-05-20

    Presently, most of the laser beam quality measurement system collimates the optical path manually with low efficiency and low repeatability. To solve these problems, this paper proposed a new collimated method to improve the reliability and accuracy of the measurement results. The system accuracy controlled the position of the mirror to change laser beam propagation direction, which can realize the beam perpendicularly incident to the photosurface of camera. The experiment results show that the proposed system has good repeatability and the measuring deviation of M2 factor is less than 0.6%. PMID:26192526

  19. Design target accuracies, data uncertainties and sensitivity studies

    The aim of this course is to give an overview of the general problem of design parameter target accuracy assessment, the related data needs and the uncertainty analysis techniques which provide the tools for these studies. Concerning target accuracy assessment, this paper is essentially based on a paper, related to LMFBR's. Data needs will be illustrated by the example of fission data needs, in all the fields of core design and fuel cycle. Uncertainty analysis is a general notion which covers different fields. In this paper we will essentially describe the so-called data adjustment aspect. Finally, the sensitivity methods, based on perturbation theory will be described for different type of applications

  20. Ultrafast High Accuracy PCRTM_SOLAR Model for Cloudy Atmosphere

    Yang, Qiguang; Liu, Xu; Wu, Wan; Yang, Ping; Wang, Chenxi

    2015-01-01

    An ultrafast high accuracy PCRTM_SOLAR model is developed based on PCA compression and principal component-based radiative transfer model (PCRTM). A fast algorithm for simulation of multi-scattering properties of cloud and/or aerosols is integrated into the fast infrared PCRTM. We completed radiance simulation and training for instruments, such as IASI, AIRS, CrIS, NASTI and SHIS, under diverse conditions. The new model is 5 orders faster than 52-stream DISORT with very high accuracy for cloudy sky radiative transfer simulation. It is suitable for hyperspectral remote data assimilation and cloudy sky retrievals.

  1. Submicron accuracy optimization for laser beam soldering processes

    Beckert, Erik; Burkhardt, Thomas; Hornaff, Marcel; Kamm, Andreas; Scheidig, Ingo; Stiehl, Cornelia; Eberhardt, Ramona; Tünnermann, Andreas

    2010-02-01

    Laser beam soldering is a packaging technology alternative to polymeric adhesive bonding in terms of stability and functionality. Nevertheless, when packaging especially micro optical and MOEMS systems this technology has to fulfil stringent requirements for accuracy in the micron and submicron range. Investigating the assembly of several laser optical systems it has been shown that micron accuracy and submicron reproducibility can be reached when using design-of-experiment optimized solder processes that are based on applying liquid solder drops ("Solder Bumping") onto wettable metalized joining surfaces of optical components. The soldered assemblies were subject to thermal cycles and vibration/ shock test also.

  2. Accuracy Improvement in Magnetic Field Modeling for an Axisymmetric Electromagnet

    Ilin, Andrew V.; Chang-Diaz, Franklin R.; Gurieva, Yana L.; Il,in, Valery P.

    2000-01-01

    This paper examines the accuracy and calculation speed for the magnetic field computation in an axisymmetric electromagnet. Different numerical techniques, based on an adaptive nonuniform grid, high order finite difference approximations, and semi-analitical calculation of boundary conditions are considered. These techniques are being applied to the modeling of the Variable Specific Impulse Magnetoplasma Rocket. For high-accuracy calculations, a fourth-order scheme offers dramatic advantages over a second order scheme. For complex physical configurations of interest in plasma propulsion, a second-order scheme with nonuniform mesh gives the best results. Also, the relative advantages of various methods are described when the speed of computation is an important consideration.

  3. Accuracy and Reliability of a New Tennis Ball Machine

    Cyril Brechbuhl, Grégoire Millet, Laurent Schmitt

    2016-01-01

    The aim was to evaluate the reliability of a newly-developed ball machine named 'Hightof', on the field and to assess its accuracy. The experiment was conducted in the collaboration of the 'Hawk-Eye' technology. The accuracy and reliability of this ball machine were assessed during an incremental test, with 1 min of exercise and 30 sec of recovery, where the frequency of the balls increased from 10 to 30 balls·min-1. The initial frequency was 10 and increased by 2 until 22, then by 1 until 30...

  4. Accuracy of transferring microparts in a multi stage former

    Mahshid, Rasoul; Hansen, Hans Nørgaard; Arentoft, Mogens

    2013-01-01

    Many fasteners used in electromechanical systems are micro metal parts which should be manufactured with high accuracy and reliability and in large quantities. Micro forming is promising to fulfill these demands. This research focuses on investigating a gripping unit in a multi stage former, as the...... and the second one is intended to depict how the unit transfers the parts with different diameters with respect to the front profile of the fingers. The experiments showed that the manipulator can handle the parts with 7 μm accuracy, 2 μm reproducibility and 9μm uncertainty for a 20mm distance between...

  5. Subpixel accuracy for extracting groove center based on corner detection

    Liu Suyi; Wang Guorong; Shi Yonghua

    2006-01-01

    Subpixel accuracy for V-groove center in robot welding is researched and a software measure to increase the accuracy of seam tracking by laser is presented.LOG( Laplacian of Gaussian ) operator is adopted to detect image edge.Vgroove center is extracted by corner detection of extremum curvature.Subpixel position is obtained by Lagarange polynomial interpolation algorithm.Experiment results show that the method is brief and applied, and is sufficient for the real time of robot welding by laser sensors.

  6. Modeling for ultrasonic testing accuracy in probabilistic fracture mechanics analysis

    This study proposes models for ultrasonic testing (UT) accuracy at In-service Inspection (ISI) in probabilistic fracture mechanics (PFM) analysis. Regression analysis of the data brought by Ultrasonic Test and Evaluation for Maintenance Standards (UTS) project and modeling for successful candidates of Performance demonstration certification system provided the models for accuracy of flaw detection and sizing. New PFM analysis code, which evaluates failure probabilities at weld lines in piping aged by Stress Corrosion Cracking, has been developed by JAEA. The models were introduced into the code. Failure probabilities under the UT models at a weld line were evaluated by the code. (author)

  7. Emotional state and its impact on voice authentication accuracy

    Voznak, Miroslav; Partila, Pavol; Penhaker, Marek; Peterek, Tomas; Tomala, Karel; Rezac, Filip; Safarik, Jakub

    2013-05-01

    The paper deals with the increasing accuracy of voice authentication methods. The developed algorithm first extracts segmental parameters, such as Zero Crossing Rate, the Fundamental Frequency and Mel-frequency cepstral coefficients from voice. Based on these parameters, the neural network classifier detects the speaker's emotional state. These parameters shape the distribution of neurons in Kohonen maps, forming clusters of neurons on the map characterizing a particular emotional state. Using regression analysis, we can calculate the function of the parameters of individual emotional states. This relationship increases voice authentication accuracy and prevents unjust rejection.

  8. Multimodal Biometric Systems - Study to Improve Accuracy and Performance

    Sasidhar, K; Ramakrishna, Kolikipogu; KailasaRao, K

    2010-01-01

    Biometrics is the science and technology of measuring and analyzing biological data of human body, extracting a feature set from the acquired data, and comparing this set against to the template set in the database. Experimental studies show that Unimodal biometric systems had many disadvantages regarding performance and accuracy. Multimodal biometric systems perform better than unimodal biometric systems and are popular even more complex also. We examine the accuracy and performance of multimodal biometric authentication systems using state of the art Commercial Off- The-Shelf (COTS) products. Here we discuss fingerprint and face biometric systems, decision and fusion techniques used in these systems. We also discuss their advantage over unimodal biometric systems.

  9. Accuracy evaluation of airborne stereo line imager data

    Gibson, J. R.; Chapman, M. A.

    The accuracy of the corrected imagery from a pushbroom stereo line imager is evaluated. The line imager system consists of the MIES II imaging system, an auxiliary data system, and a postflight data-processing system. The imagery and navigation data are tied to ground control points by a photogrammetric bundle adjustment to resolve low-frequency position errors. The accuracy of the correct imagery was found to be 1.5 pixels rms in position and 0.5 pixels rms in height.

  10. ACCURACY OF A 3D VISION SYSTEM FOR INSPECTION

    Carmignato, Simone; Savio, Enrico; De Chiffre, Leonardo

    ABSTRACT. This paper illustrates an experimental method to assess the accuracy of a three-dimensional (3D) vision system for the inspection of complex geometry. The aim is to provide a procedure to evaluate task related measurement uncertainty for virtually any measurement task. The key element of...... purpose to establish traceability. Accuracy performances of optical digitisation systems are assessed on the basis of deviations existing between acquired cloud points and the CMM measurements. To demonstrate the feasibility of the proposed method, the procedure is applied to an industrial case study....