Relevant bibliographies by topics / Velocity Uncertainty

Academic literature on the topic 'Velocity Uncertainty'

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Published: 10 December 2022
Last updated: 28 January 2023

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Journal articles on the topic "Velocity Uncertainty"

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Avila Farenzena, Bruno, and Jorge Hugo Silvestrini. "Density currents front velocity uncertainty." Computers & Fluids 232 (January 2022): 105209. http://dx.doi.org/10.1016/j.compfluid.2021.105209.

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Chen, Yue, Harold E. Bedell, Laura J. Frishman, and Dennis M. Levi. "Stimulus uncertainty affects velocity discrimination." Vision Research 38, no. 9 (May 1998): 1265—IN2. http://dx.doi.org/10.1016/s0042-6989(97)00282-4.

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Poliannikov, Oleg V., and Alison E. Malcolm. "The effect of velocity uncertainty on migrated reflectors: Improvements from relative-depth imaging." GEOPHYSICS 81, no. 1 (January 1, 2016): S21—S29. http://dx.doi.org/10.1190/geo2014-0604.1.

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We have studied the problem of uncertainty quantification for migrated images. A traditional migrated image contains deterministic reconstructions of subsurface structures. However, input parameters used in migration, such as reflection data and a velocity model, are inherently uncertain. This uncertainty is carried through to the migrated images. We have used Bayesian analysis to quantify the uncertainty of the migrated structures by constructing a joint statistical distribution of the location of these structures. From this distribution, we could deduce the uncertainty in any quantity derived from these structures. We have developed the proposed framework using a simple model with velocity uncertainty in the overburden, and we estimated the absolute positions of the horizons and the relative depth of one horizon with respect to another. By quantifying the difference in the corresponding uncertainties, we found that, in this case, the relative depths of the structures could be estimated much better than their absolute depths. This analysis justifies redatuming below an uncertain overburden for the purposes of the uncertainty reduction.
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Steinbock, J., A. Weissenbrunner, M. Juling, T. Lederer, and P. U. Thamsen. "Uncertainty evaluation for velocity–area methods." Flow Measurement and Instrumentation 48 (April 2016): 51–56. http://dx.doi.org/10.1016/j.flowmeasinst.2015.09.007.

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Zhang, Jiacheng, Sayantan Bhattacharya, and Pavlos P. Vlachos. "Uncertainty of PIV/PTV based Eulerian pressure estimation using velocity uncertainty." Measurement Science and Technology 33, no. 6 (March 10, 2022): 065303. http://dx.doi.org/10.1088/1361-6501/ac56bf.

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Abstract This work introduces a method to estimate the uncertainty of the pressure fields reconstructed from particle image velocimetry / particle tracking velocimetry (PIV/PTV) measurements by propagating the instantaneous velocity vector uncertainty through the pressure reconstruction. The uncertainty propagations through the calculation and integration of pressure gradients are modelled as linear transformations. The autocorrelation coefficient was modelled and incorporated in the uncertainty estimation to reproduce the effect of the autocorrelation of velocity errors on the reconstructed pressure’s accuracy. The method was first tested on synthetic velocity fields contaminated with varying levels of artificial noise correlated in space, time, or between components. The error analysis shows that the proposed method could predict the spatiotemporal variations of the pressure errors. The estimated pressure uncertainty also captures the effects of the velocity noise level, the autocorrelation, and the different pressure-gradient integration methods, with more than 80% accuracy in most test cases. The method was applied to an experimental vortex ring flow with planar PIV and a laminar pipe flow with volumetric PTV. The error analysis shows that the obtained pressure uncertainty possessed similar spatial and statistical distributions as the pressure errors. The results also indicate that the performance of the proposed uncertainty estimation method depends on the accuracy of the velocity uncertainty. The proposed uncertainty estimation method exhibits reliability in obtaining the local and instantaneous pressure uncertainty from the PIV/PTV measurements.
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Grubb, H., A. Tura, and C. Hanitzsch. "Estimating and interpreting velocity uncertainty in migrated images and AVO attributes." GEOPHYSICS 66, no. 4 (July 2001): 1208–16. http://dx.doi.org/10.1190/1.1487067.

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Estimating a suitable velocity field for use in prestack depth migration is inherently uncertain because of limitations on the available data and estimation techniques. This uncertainty affects both the migrated depth of structures and their amplitudes in the inverted images. These effects can be estimated by performing multiple migrations with a set of velocity fields and colocating features in the migrated images. This lets us examine the imaging procedure’s sensitivity to changes in the velocity field so we can assess both structural and amplitude uncertainties in migrated images. These two types of uncertainties affect interpretation in different ways. For instance, with structural uncertainty interpretation we consider the change in migrated location of structures when deciding on drilling locations, optimizing well trajectories, or computing uncertainty in volumetric calculations. With amplitude uncertainty or amplitude versus offset (AVO) uncertainty interpretation, we consider (1) uncertainty in crossplots of pairs of AVO attributes at a point of interest or (2) uncertainty of the attribute values along identified structures. For any interpretation informing a decision, the uncertainty can help estimate risk. Our data processing approach is based on amplitude‐preserving prestack depth migration followed by AVO inversion, or AVO migration/inversion. It is valid for estimating AVO attributes in simple to moderately complex structural settings. Our methods of assessing the effect of velocity uncertainty can also be applied when obtaining structural uncertainties for a complex overburden geology or amplitude uncertainties in conventional NMO‐based AVO analysis. They may also be applied straightforwardly to any poststack attribute analysis. Key to the approach is the availability of multiple velocity fields to generate multiple migrated images. In our application, an automatic algorithm samples possible fields, but the set of fields to consider could be generated from another source, such as interpretation.
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Yilmaz, Öz. "Circumventing velocity uncertainty in imaging complex structures." Leading Edge 37, no. 1 (January 2018): 14–18. http://dx.doi.org/10.1190/tle37010014.1.

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Renbiao Wu, Kunlong Gu, Jian Li, J. Habersat, and G. Maksymonko. "Propagation velocity uncertainty on GPR SAR processing." IEEE Transactions on Aerospace and Electronic Systems 39, no. 3 (July 2003): 849–61. http://dx.doi.org/10.1109/taes.2003.1238741.

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Coveney, Sam, Cesare Corrado, Caroline H. Roney, Daniel O’Hare, Steven E. Williams, Mark D. O’Neill, Steven A. Niederer, Richard H. Clayton, Jeremy E. Oakley, and Richard D. Wilkinson. "Gaussian process manifold interpolation for probabilistic atrial activation maps and uncertain conduction velocity." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2173 (May 25, 2020): 20190345. http://dx.doi.org/10.1098/rsta.2019.0345.

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In patients with atrial fibrillation, local activation time (LAT) maps are routinely used for characterizing patient pathophysiology. The gradient of LAT maps can be used to calculate conduction velocity (CV), which directly relates to material conductivity and may provide an important measure of atrial substrate properties. Including uncertainty in CV calculations would help with interpreting the reliability of these measurements. Here, we build upon a recent insight into reduced-rank Gaussian processes (GPs) to perform probabilistic interpolation of uncertain LAT directly on human atrial manifolds. Our Gaussian process manifold interpolation (GPMI) method accounts for the topology of the atrium, and allows for calculation of statistics for predicted CV. We demonstrate our method on two clinical cases, and perform validation against a simulated ground truth. CV uncertainty depends on data density, wave propagation direction and CV magnitude. GPMI is suitable for probabilistic interpolation of other uncertain quantities on non-Euclidean manifolds. This article is part of the theme issue ‘Uncertainty quantification in cardiac and cardiovascular modelling and simulation’.
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Poliannikov, Oleg V., Michael Prange, Alison E. Malcolm, and Hugues Djikpesse. "Joint location of microseismic events in the presence of velocity uncertainty." GEOPHYSICS 79, no. 6 (November 1, 2014): KS51—KS60. http://dx.doi.org/10.1190/geo2013-0390.1.

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The locations of seismic events are used to infer reservoir properties and to guide future production activity, as well as to determine and understand the stress field. Thus, locating seismic events with uncertainty quantification remains an important problem. Using Bayesian analysis, a joint probability density function of all event locations was constructed from prior information about picking errors in kinematic data and explicitly quantified velocity model uncertainty. Simultaneous location of all seismic events captured the absolute event locations and the relative locations of some events with respect to others, along with their associated uncertainties. We found that the influence of an uncertain velocity model on location uncertainty under many realistic scenarios can be significantly reduced by jointly locating events. Many quantities of interest that are estimated from multiple event locations, such as fault sizes and fracture spacing or orientation, can be better estimated in practice using the proposed approach.
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Dissertations / Theses on the topic "Velocity Uncertainty"

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Bermuske, Mike, Lars Büttner, and Jürgen Czarske. "Measurement uncertainty budget of an interferometric flow velocity sensor." SPIE, 2017. https://tud.qucosa.de/id/qucosa%3A35151.

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Flow rate measurements are a common topic for process monitoring in chemical engineering and food industry. To achieve the requested low uncertainties of 0:1% for flow rate measurements, a precise measurement of the shear layers of such flows is necessary. The Laser Doppler Velocimeter (LDV) is an established method for measuring local flow velocities. For exact estimation of the flow rate, the flow profile in the shear layer is of importance. For standard LDV the axial resolution and therefore the number of measurement points in the shear layer is defined by the length of the measurement volume. A decrease of this length is accompanied by a larger fringe distance variation along the measurement axis which results in a rise of the measurement uncertainty for the flow velocity (uncertainty relation between spatial resolution and velocity uncertainty). As a unique advantage, the laser Doppler profile sensor (LDV-PS) overcomes this problem by using two fan-like fringe systems to obtain the position of the measured particles along the measurement axis and therefore achieve a high spatial resolution while it still offers a low velocity uncertainty. With this technique, the flow rate can be estimated with one order of magnitude lower uncertainty, down to 0:05% statistical uncertainty.1 And flow profiles especially in film flows can be measured more accurately. The problem for this technique is, in contrast to laboratory setups where the system is quite stable, that for industrial applications the sensor needs a reliable and robust traceability to the SI units, meter and second. Small deviations in the calibration can, because of the highly position depending calibration function, cause large systematic errors in the measurement result. Therefore, a simple, stable and accurate tool is needed, that can easily be used in industrial surroundings to check or recalibrate the sensor. In this work, different calibration methods are presented and their in uences to the measurement uncertainty budget of the sensor is discussed. Finally, generated measurement results for the film flow of an impinging jet cleaning experiment are presented.
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Anderson, Kimberly Rose. "Quantifying Uncertainty in Low Velocity Human Aspiration Studies: Effect of Secondary Aspiration and Thin-walled Reference Sampling in Low Velocity Conditions." Diss., University of Iowa, 2013. https://ir.uiowa.edu/etd/4812.

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In order to evaluate a biologically relevant measure of exposure, inhalable samplers are designed to match the aspiration efficiency of the human head. Human inhalability is evaluated in wind tunnel studies using mannequins as human surrogates or using numerical and computational methods. There has been differences between human aspiration efficiency estimates using wind tunnel studies and computational fluid dynamics (CFD) modeling, particularly for larger particle sizes (>68 µm). The objective of this dissertation was to evaluate biases in low velocity inhalability studies in an effort to explain the discrepancies in results between experimental and computational inhalability studies. This research addressed the phenomena of secondary aspiration on human facial skin, evaluated the appropriateness of mannequin surfaces as surrogates for humans, and evaluated the performance of the thin-walled reference sampler in low velocities to quantify potential biases in low velocity inhalability studies. The first study determined a realistic coefficient of restitution (CoR) for human facial skin over a range of ages under nine environmental conditions. This study found human facial skin is non-uniform across the face and identified significant interaction between age and sampling location, indicating that how CoR varies with age is dependent on the location sampled. The second study applied the average CoR values for forehead, cheeks and nose in CFD simulations to evaluate the effect of secondary aspiration on human aspiration efficiency estimates and determine how refined the CoR value needed to be to accurately model human aspiration efficiency. This study identified significant increases in aspiration when allowing for particle bounce, but no significant differences between uniform CoRs of 0.5, 0.8 and 1.0, indicating differences between different mannequin surfaces and particle interactions would have minimal effect on aspiration efficiency estimates. The third study evaluated the performance of a horizontally-aligned reference sampler in low wind speeds (0.1 to 0.4 m s-1). While significant differences from unity were identified, differences ranged from -1 to 6% and would have a negligible effect on sampler efficiency estimates. The use of a horizontally-aligned isokinetic reference sampler was found to be appropriate in freestream velocities ranging from 0.1 to 0.4 m s-1.
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Niemiec, Łukasz. "Určení nejistot při stanovení průtoků ve vodních tocích pomocí měření hydrometrickou vrtulí." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-233793.

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The development of hydrology and the need of getting exact data increase the demands on hydro metering. Measurement of spot velocities and deriving the flow of water are frequently performed by the workers of Český hydrometeorologický ústav (Czech Hydrometeorological Institute) and other companies. The limited precision of the measuring machines, the imperfection of methods and the influence of human senses cause that we are not able to get the accurate value of quantity. We are just close to the right values. The term uncertainty of measuring determines the interval which is assigned to each measurement and contains the real value of measured quantity. Twenty imminently repeated measurement were done in twelve measuring profiles of the Dyje River and in one profile of the Morava River using the current meters OTT (OTT Hydromet, 2013) type C2 and type C31. We investigated the dependence of uncertainties type A and B in different profile parameter. The measurement was done with the suspension bar with 2 to 4 propeller current-meters. The hydrometric car on the bridge was used in deeper waters. The results were analysed from the point of view of the uncertainties and generalized. Next point of the research was to find out how the frequency of the current meter depends on temperature of water. For this purpose, the specific canal was made in the Faculty of Civil Engineering in Brno (Ústav vodního hospodářství krajiny) and the measuring was done in temperature interval from 1 °C to 24 °C. Repeated measuring was statistically evaluated from the uncertainties point of view. In the thesis, the proposal of elaboration of uncertainties determined by both types of measurement into current methods of determination of uncertainties of the derived flows using the measurement of spot velocity by the propeller current-meter in measuring profiles of the rivers is introduced.
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Nitschke, Christian Thomas. "Quantification d'incertitudes aléatoires et épistémiques dans la prédiction d'instabilités aéroélastiques." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS022/document.

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La vitesse critique de flottement est un facteur essentiel à la conception aéronautique car elle caractérise le régime de vol au-delà duquel l’aéronef risque de subir un mécanisme de ruine. L’objectif de cette thèse est d’étudier l’impact des incertitudes d’origines aléatoires et épistémiques sur la limite de stabilité linéaire pour des configurations aéroélastiques idéalisées. Dans un premier temps, un problème de propagation directe d’incertitudes aléatoires relatives à des paramètres de fabrication d’une aile en forme de plaque en matériau composite stratifié a été considéré. La représentation du matériau par la méthode polaire lève la contrainte de grande dimensionnalité du problème stochastique initial et permet l’utilisation du Chaos Polynômial. Cependant, la corrélation introduite par cette paramétrisation nécessite une adaptation de la base polynômiale. Enfin, un algorithme d’apprentissage automatique a été employé pour traiter des discontinuités dans le comportement modal des instabilités aéroélastiques. Le second volet de la thèse concerne la quantification d’incertitudes de modélisation de caractère épistémique qui sont introduites au niveau de l’opérateur aérodynamique. Ces travaux, menés à partir d’un formalisme Bayésien, permettent non seulement d’établir des probabilités de modèle, mais aussi de calibrer les coefficients des modèles dans un contexte stochastique afin d’obtenir des prédictions robustes pour la vitesse critique. Enfin, une étude combinée des deux types d’incertitude permet d’améliorer le processus de calibration
The critical flutter velocity is an essential factor in aeronautic design because it caracterises the flight envelope outside which the aircraft risks to be destroyed. The goal of this thesis is the study of the impact of uncertainties of aleatory and epistemic origin on the linear stability limit of idealised aeroelastic configurations. First, a direct propagation problem of aleatory uncertainties related to manufacturing parameters of a rectangular plate wing made of a laminated composite material was considered. The representation of the material through the polar method alleviates the constraint of the high number of dimensions of the initial stochastic problem, which allows the use of polynomial chaos. However, the correlation which is introduced by this parametrisation requires an adaption of the polynomial basis. Finally, a machine learning algorithm is employed for the treatment of discontinuities in the modal behaviour of the aeroelastic instabilities. The second part of the thesis is about the quantification of modelling uncertainties of epistemic nature which are introduced in the aerodynamic operator. This work, which is conducted based on a Bayesian formalism, allows not only to establish model probabilities, but also to calibrate the model coefficients in a stochastic context in order to obtain robust predictions for the critical velocity. Finally, a combined study of the two types of uncertainty allows to improve the calibration process
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Janečka, Jan. "Návrh zařízení pro měření a hodnocení tepelného stavu prostředí." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-234012.

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The thesis deals with evaluation of the environmental thermal state in closed rooms with people inside the room. The achievement of thermal comfort is related to thermal balance of human body. People are producing heat during their work, which has to be carried away from the body to surrounding area by radiation, convection, conduction, respiration and evaporation. The intensity of heat removal is influenced by environmental parameters, especially by air temperature, mean radiant temperature, air velocity and humidity. Personal factors as energy expenditure of human body and clothing resistance are influencing the intensity of heat removal as well. People are able to influence the thermal comfort by their behaviour in given environment, appropriate clothing and regulation of basic environmental parameters. CSN EN ISO 7730 standard states that environmental parameters should be estimated or measured. The operative temperature is than evaluated from collected data. This operative temperature is defined as the temperature of black enclosed area where the human body will be by convection and radiation sharing the same amount of heat as in real inconsistent environment. Nowadays on the market there is no cheap solution for sensor which is able to evaluate the operating temperature and could be used in buildings. There are a lot of professional sensors which have very high accuracy, but are very expensive. Therefore are mainly used only for research or for single and exceptional measurement of environmental thermal state in rooms. The thesis is therefore focused on proposal of suitable (compact) operative temperature sensor assembled according to valid regulations and standards. Emphasis is placed mainly on the sensor price together with guarantee of sufficient accuracy. The proposed sensor is providing information to control system which is than able to adjust the parameters of environment using appropriate way based on relevant requirements. Here is some space for energy savings due to possible continuous measurement and evaluation of environmental thermal state in different rooms. Therefore, during continuous measurement no unnecessary rooms overheating in winter as well as unreasonable cooling in summer should occur. This research and solution is than reflected in reduction of energy consumption used for building operation and subsequently reduction of the pollutants production. This issue is being watched with increasing interest. Another advantage is that whole system is able to work autonomously without human intervention. People no longer have to continuously adjust air temperature because the control system is able to evaluate the most appropriate adjustments based on objective data obtained from the sensor. The thesis includes subsequent verification of proposed sensor as well as the definition of sensor technical parameters including analysis of measurement uncertainties.
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Alwash, Maitham Fadhil Abbas. "Assessment of concrete strength in existing structures using nondestructive tests and cores : analysis of current methodology and recommendations for more reliable assessment." Thesis, Bordeaux, 2017. http://www.theses.fr/2017BORD0587/document.

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Pour évaluer la résistance mécanique du béton dans un ouvrage existant, la méthodologie courante combine des mesures non destructives (CND) comme le rebond ou/et la vitesse des ondes ultrasoniques avec la technique destructive (carottes) afin de produire une relation‘‘modèle de conversion” entre la résistance mécanique et les mesures CND. Le modèle de conversion est utilisé pour estimer la valeur locale de résistance mécanique à chaque emplacement de test en utilisant la valeur CND correspondante. Ensuite, on calcule les estimations de la résistance moyenne et/ou de l’écart-type de la résistance (variabilité de la résistance du béton). Cependant, la fiabilité d’estimation est toujours discutable en raison des incertitudes associées à l’évaluation de la résistance basée sur les mesures CND. Pour améliorer la fiabilité, les incertitudes doivent être réduites en spécifiant et en contrôlant leurs facteurs d’influence. Par conséquent, l’objectif de cette thèse est d’analyser la méthodologie d’évaluation courante afin de fournir des recommandations pratiques qui peuvent améliorer la fiabilité de l’évaluation de la résistance in-situ du béton dans les ouvrages existantes par des tests non destructifs et des carottes.Pour ce but, un simulateur a été construit afin d’analyser les effets des facteurs les plus influents en utilisant une vaste campagne de données provenant de sources différentes (études in situ ou en laboratoire et données synthétiques générées). La première contribution de ce travail est le développement d’une nouvelle approche d’identification du modèle ‘‘bi-objectif” qui peut efficacement capturer la variabilité de la résistance mécanique en plus de la moyenne. Après avoir étudié l’effet du mode de sélection des emplacements pour les carottes, une méthode a été proposée pour sélectionner ces emplacements en fonction des mesures CND ‘‘sélection conditionnelle” qui améliore la qualité de l’évaluation sans coût supplémentaire. Une dernière innovation est l’établissement de courbes de risque qui quantifient la relation entre le nombre de carottes et la précision de l’estimation. Enfin, des recommandations ont été formulées afin de fournir des estimations plus fiables
To assess concrete strength in an existing structure, the current methodology combines nondestructive measurements (NDT) like rebound hammer or/and pulse velocity with destructive technique (cores) in order to implement a relationship ‘‘conversion model” between the compressive strength and NDT measurements. The conversion model is used to estimate the local strength value at each test location using the corresponding NDT value.Then the estimated mean strength and/or estimated strength standard deviation (concrete strength variability) values are calculated. However, the reliability of these estimated values isalways a questionable issue because of the uncertainties associated with the strength assessment based upon NDT measurements. To improve the reliability, the uncertainties must be reduced by specifying and controlling their influencing factors. Therefore, the objective of this thesis is to analyze the current assessment methodology in order to provide practical recommendations that can improve the reliability of assessing the in-situ strength in existing concrete structures by nondestructive tests and cores.To this end, a simulator was built in order to analyze the effects of the most influencing factors using a large campaign of datasets from different sources (in-situ or laboratory studies,and generated synthetic data).The first contribution of this work is the development of a new model identification approach“bi-objective” that can efficiently capture the strength variability in addition to the mean strength. After studying the effect of the way of selection the core locations, a method was proposed to select these locations depending on the NDT measurements “conditional selection” that improves the quality of assessment without additional cost. A third innovation was the development of a procedure to identify the relation between the number of cores and the accuracy of the estimation. Finally recommendations were derived in order to providemore reliable estimated values
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Vestin, Albin, and Gustav Strandberg. "Evaluation of Target Tracking Using Multiple Sensors and Non-Causal Algorithms." Thesis, Linköpings universitet, Reglerteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-160020.

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Today, the main research field for the automotive industry is to find solutions for active safety. In order to perceive the surrounding environment, tracking nearby traffic objects plays an important role. Validation of the tracking performance is often done in staged traffic scenarios, where additional sensors, mounted on the vehicles, are used to obtain their true positions and velocities. The difficulty of evaluating the tracking performance complicates its development. An alternative approach studied in this thesis, is to record sequences and use non-causal algorithms, such as smoothing, instead of filtering to estimate the true target states. With this method, validation data for online, causal, target tracking algorithms can be obtained for all traffic scenarios without the need of extra sensors. We investigate how non-causal algorithms affects the target tracking performance using multiple sensors and dynamic models of different complexity. This is done to evaluate real-time methods against estimates obtained from non-causal filtering. Two different measurement units, a monocular camera and a LIDAR sensor, and two dynamic models are evaluated and compared using both causal and non-causal methods. The system is tested in two single object scenarios where ground truth is available and in three multi object scenarios without ground truth. Results from the two single object scenarios shows that tracking using only a monocular camera performs poorly since it is unable to measure the distance to objects. Here, a complementary LIDAR sensor improves the tracking performance significantly. The dynamic models are shown to have a small impact on the tracking performance, while the non-causal application gives a distinct improvement when tracking objects at large distances. Since the sequence can be reversed, the non-causal estimates are propagated from more certain states when the target is closer to the ego vehicle. For multiple object tracking, we find that correct associations between measurements and tracks are crucial for improving the tracking performance with non-causal algorithms.
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Dussaud, Eric Albert. "Velocity analysis in the presence of uncertainty." Thesis, 2005. http://hdl.handle.net/1911/18897.

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Velocity analysis resolves relatively long scales of earth structure, on the order of 1 km. Migration produces images with length scales (wavelengths) on the order of 10's of m. In between these two scale regimes lies another, corresponding roughly to structures between 60 to 300m in extent, in which the resolution of velocity analysis is uncertain and the energy of images is small to non-existent. This thesis aims at assessing the impact on velocity analysis of uncertainty at these intermediate length scales, using ideas on time reversal and imaging in randomly inhomogeneous media developed by Borcea and colleagues, in combination with velocity estimation methods of differential semblance type. The main result of this thesis is that the noise in seismic reflection data associated with the middle scales in velocity heterogeneity does not strongly affect the estimates of the long-scale component of velocity, if these estimates are obtained using a statistically stable formulation of differential semblance optimization. Hence the nonlinear influence of uncertainty in the middle scales does not propagate down the length scale. This is in contrast with the results of Borcea and colleagues, who have shown that prestack images are strongly affected, implying that the uncertainty in the middle scales does certainly propagate up the length scale. Random perturbations associated with the middle scales of velocity heterogeneity yield measurable phase shifts in the reflection data. However, it is known that cross-correlations of neighboring seismic traces are stable against these perturbations, under some circumstances. The main theoretical achievement of this thesis, presented in Chapter 3, is to extend this stability result to laterally homogeneous background velocity models, and to cross-correlations containing slowly-varying weights. Chapter 4 shows that differential semblance functionals, specialized to layered modeling, can be written entirely in terms of weighted cross-correlations, and therefore argues that the velocity analysis algorithm and the associated velocity estimates inherit the statistical stability property. A quantitative verification of the stability claims is provided in Chapter 5.
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Luo, Hao. "Tsallis Entropy Based Velocity Distribution in Open Channel Flows." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-462.

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The Tsallis entropy is applied to derive both 1-D and 2-D velocity distributions in an open channel cross section. These distributions contain a parameter m through which the Tsallis entropy becomes a generalization of the Shannon entropy. Different m parameter values are examined to determine the best value for describing the velocity distribution.Two Lagrangian parameters that are involved in the final form of 1-D velocity distribution equation are determined from observations of mean velocity and the maximum velocity at the water surface. For channels which are not wide and where the maximum velocity does not occur at the water surface, a 2-D velocity distribution is more appropriate. The Tsallis entropy is applied to derive 2-D velocity distributions. A new parameter M is introduced which represents the hydraulic characteristics of the channel. The derived velocity distributions are verified using both field data and experimental data. The advantages are found by comparing with Parandtl-von Karman, power law and Chiu’s velocity distributions.
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HAUNG, CHI-HSIANG, and 黃氣祥. "Stochastic sediment transport modeling: fluctuation sediment concentrations, Non-Fickian diffusivity, settling velocity uncertainty." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/5bjc84.

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碩士
國立臺灣大學
土木工程學研究所
105
The uncertainty of the sediment transport cannot be neglected according to the turbulent bursting. The study adapted two methods to calculated the uncertainty of sediment transport and one method to improved uncertainty analysis method. The first method (first topic) is based on the advection diffusion equation which is in diffusion region. The uncertain of the movement of the sediment particle can be simulated by stochastic particle tracking method(SPTM). By Markov Chain, SPTM can be simplified and calculated the uncertainty of the sediment concentration efficiency. First, the uncertainty of the spatial and temporal sediment concertation caused by the particle size can be calculated. With a similar particle size, the change of temporal sediment concertation is explicit. Secondly the uncertain of the equilibrium sediment concentration caused by fluctuation of turbulence will be estimated. The result of sediment concertation by proposed model is validated against the experiment data and can better describe sediment concentration than the deterministic model (Rouse profile). The first method is more suitable to described the sediment concentration under condition of suspended load. The second method is focus on the trajectory of the sediment particle in non-diffusion region. The particle is force by lifting, gravity, drag, Buoyancy forces. To calculated the foundation force, the more accuracy flow velocity is created by gram charily expansion which considering four order moment of the fluctuation. The bed condition in the study adapt a rebound process. The particle will collide with stochastic particle alignment. In this (second) topic, firstly, the saltation length and height calculated by the proposed model will be validated by experiment. The saltation length and height in the smooth bed is higher than that in rough bed. Secondly the sediment concentration under suspend and bed load condition is compared with Rouse profile and experiment data. Third the supdiffusion and subdiffusion will be discussed. In the first and second topic, the uncertainty of the sediment concentration is calculated by the Monte Carlo Simulation which is extremely time consuming. In the third topic, two new methods are provided. The results simulated by two methods are compared with Simpson method. The first method is derived from the point estimated method(PEM) which only used two or three points. By increasing the accuracy of the simulated result by PEM, the adequative method is used to increase the simulation points. Secondly, Gram Charlier expansion and Hermit Gauss Quadrature is adapted to calculated by uncertainty in the second method. First method is suitable when the simulation points are few and the distribution of the random variable is known. The second method is suitable when the statistical moment of the random variable is only known. The converge of the second method is faster than the other two methods.Key words: Particle tracking method, Markov chain, higher order flow field, Modified Hermite Gauss integral, Adequative Hong’s method.
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Books on the topic "Velocity Uncertainty"

1

J, Wendt Bruce, and United States. National Aeronautics and Space Administration., eds. A new algorithm for five-hole probe calibration, data reduction, and uncertainty analysis. [Washington, DC]: National Aeronautics and Space Administration, 1994.

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J, Wendt Bruce, and United States. National Aeronautics and Space Administration., eds. A new algorithm for five-hole probe calibration, data reduction, and uncertainty analysis. [Washington, DC]: National Aeronautics and Space Administration, 1994.

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J, Wendt Bruce, and United States. National Aeronautics and Space Administration., eds. A new algorithm for five-hole probe calibration, data reduction, and uncertainty analysis. [Washington, DC]: National Aeronautics and Space Administration, 1994.

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A new algorithm for five-hole probe calibration, data reduction, and uncertainty analysis. [Washington, DC]: National Aeronautics and Space Administration, 1994.

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Book chapters on the topic "Velocity Uncertainty"

1

Zhang, Geng, Dihua Sun, Min Zhao, Hui Liu, Dong Chen, and Yang Li. "Stability Analysis of Car-Following Model with Uncertainty in Perceiving Velocity." In Advances in Intelligent Systems and Computing, 409–15. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-38789-5_50.

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Corato, G., T. Moramarco, T. Tucciarelli, and J. W. Fulton. "Continuous Discharge Monitoring Using Non-contact Methods for Velocity Measurements: Uncertainty Analysis." In Engineering Geology for Society and Territory - Volume 3, 617–21. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-09054-2_123.

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Guedes, Bruno Rocha, Marcelo Lobosco, Rodrigo Weber dos Santos, and Ruy Freitas Reis. "Uncertainty Quantification of Tissue Damage Due to Blood Velocity in Hyperthermia Cancer Treatments." In Computational Science – ICCS 2021, 511–24. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-77964-1_39.

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Zhou, Guoqiang, and Rongyi Cui. "An Approach to Scene Segmentation Based on Energy and Uncertainty Distribution of Velocity Field." In Communications in Computer and Information Science, 520–28. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-31968-6_62.

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Nagib, H., P. Monkewitz, L. Mascotelli, G. Bellani, and A. Talamelli. "Uncertainty Analysis of the Von Kàrmàn Constant for the Mean Centerline Velocity in CICLoPE." In Springer Proceedings in Physics, 197–202. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-22196-6_31.

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Fiorini, Camilla, Pierre-Marie Boulvard, Long Li, and Etienne Mémin. "A Two-Step Numerical Scheme in Time for Surface Quasi Geostrophic Equations Under Location Uncertainty." In Mathematics of Planet Earth, 57–67. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-18988-3_5.

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AbstractIn this work we consider the surface quasi-geostrophic (SQG) system under location uncertainty (LU) and propose a Milstein-type scheme for these equations, which is then used in a multi-step method. The SQG system considered here consists of one stochastic partial differential equation, which models the stochastic transport of the buoyancy, and a linear operator linking the velocity and the buoyancy. In the LU setting, the Euler-Maruyama scheme converges with weak order 1 and strong order 0.5. Our aim is to develop higher order schemes in time, based on a Milstein-type scheme in a multi-step framework. First we compared different kinds of Milstein schemes. The scheme with the best performance is then included in the two-step scheme. Finally, we show how our two-step scheme decreases the error in comparison to other multi-step schemes.
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Mrokowska, Magdalena M., Paweł M. Rowiński, and Monika B. Kalinowska. "The Uncertainty of Measurements in River Hydraulics: Evaluation of Friction Velocity Based on an Unrepeatable Experiment." In GeoPlanet: Earth and Planetary Sciences, 195–206. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-30209-1_13.

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Liu, Yongbo, Zhuoshi Chen, Xiaoming Yuan, and Longwei Chen. "The Uncertainty of In-situ S and P Wave Velocity Test at Xichang Experimental Field of CSES." In Proceedings of the 4th International Conference on Performance Based Design in Earthquake Geotechnical Engineering (Beijing 2022), 944–51. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-11898-2_71.

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Schmidt-Böcking, H., S. Eckart, H. J. Lüdde, G. Gruber, and T. Jahnke. "The Precision Limits in a Single-Event Quantum Measurement of Electron Momentum and Position." In Molecular Beams in Physics and Chemistry, 223–45. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63963-1_12.

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AbstractA modern state-of-the-art “quantum measurement” [The term “quantum measurement” as used here implies that parameters of atomic particles are measured that emerge from a single scattering process of quantum particles.] of momentum and position of a single electron at a given time [“at a given time” means directly after the scattering process. (It should be noticed that the duration of the reaction process is typically extremely short => attoseconds).] and the precision limits for their experimental determination are discussed from an experimentalists point of view. We show—by giving examples of actually performed experiments—that in a single reaction between quantum particles at a given time only the momenta of the emitted particles but not their positions can be measured with sub-atomic resolution. This fundamental disparity between the conjugate variables of momentum and position is due to the fact that during a single-event measurement only the total momentum but not position is conserved as function of time. We highlight, that (other than prevalently perceived) Heisenberg’s “Uncertainty Relation” UR [1] does not limit the achievable resolution of momentum in a single-event measurement. Thus, Heisenberg’s statement that in a single-event measurement only either the position or the momentum (velocity) of a quantum particle can be measured with high precision contradicts a real experiment. The UR states only a correlation between the mean statistical fluctuations of a large number of repeated single-event measurements of two conjugate variables. A detailed discussion of the real measurement process and its precision with respect to momentum and position is presented.
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Liu, Yuan, and Shangzheng Liu. "Smooth Globally Convergent Velocity Observer Design for Uncertain Robotic Manipulators." In Lecture Notes in Electrical Engineering, 526–34. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-32-9682-4_55.

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Conference papers on the topic "Velocity Uncertainty"

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Lynn, Walt. "Azimuthal interval velocity uncertainty." In SEG Technical Program Expanded Abstracts 2011. Society of Exploration Geophysicists, 2011. http://dx.doi.org/10.1190/1.3627776.

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Haas, A., P. Thore, and J. Arnaud. "Structural Uncertainty Determination by Statistical Analysis." In EAEG/SEG Summer Workshop - Construction of 3-D Macro Velocity-Depth Models. European Association of Geoscientists & Engineers, 1994. http://dx.doi.org/10.3997/2214-4609.201407576.

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J. Grubb, H., A. Tura, and C. Hanitzsch. "Migration Velocity Uncertainty and AVO Attributes." In EAGE/SEG Workshop - Depth Imaging of Reservoir Attributes. European Association of Geoscientists & Engineers, 1998. http://dx.doi.org/10.3997/2214-4609.201406687.

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Davison, Chris, Andrew Ratcliffe, Sergio Grion, Rodney Johnston, Carlos Duque, Jeremy Neep, and Musa Maharramov. "Azimuthal velocity uncertainty: Estimation and application." In SEG Technical Program Expanded Abstracts 2011. Society of Exploration Geophysicists, 2011. http://dx.doi.org/10.1190/1.3627743.

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Lynn, Walt. "Uncertainty implications in azimuthal velocity analysis." In SEG Technical Program Expanded Abstracts 2007. Society of Exploration Geophysicists, 2007. http://dx.doi.org/10.1190/1.2792387.

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Gautam, Suman, Jianchun Dai, Nadxieli De La Rosa Perez, and Andrew Jalbert. "Rock physics based velocity modeling for reducing subsalt velocity uncertainty." In SEG Technical Program Expanded Abstracts 2017. Society of Exploration Geophysicists, 2017. http://dx.doi.org/10.1190/segam2017-17538873.1.

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Mair Sdn Bhd, Dylan, and Lee Hong Shien. "Scenario-based Velocity Modeling forDepth Conversion Uncertainty." In PGCE 2005. European Association of Geoscientists & Engineers, 2005. http://dx.doi.org/10.3997/2214-4609-pdb.257.11.

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Poliannikov*, Oleg V., and Alison E. Malcolm. "Effect of velocity uncertainty on migrated reflectors." In SEG Technical Program Expanded Abstracts 2014. Society of Exploration Geophysicists, 2014. http://dx.doi.org/10.1190/segam2014-1359.1.

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La Jeunesse, Jeff W., Peter A. Sable, and John P. Borg. "Uncertainty analysis for transverse surface velocity measurements." In SHOCK COMPRESSION OF CONDENSED MATTER - 2019: Proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter. AIP Publishing, 2020. http://dx.doi.org/10.1063/12.0000875.

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González-Castro, Juan A., and Zhiming Chen. "Uncertainty of Index-Velocity Measurements at Culverts." In World Water and Environmental Resources Congress 2005. Reston, VA: American Society of Civil Engineers, 2005. http://dx.doi.org/10.1061/40792(173)450.

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Reports on the topic "Velocity Uncertainty"

1

Li, Q., J. Shimeld, K. Dickie, S. A. Dehler, D. Mosher, and K. Desroches. Seismic velocity modelling, fixed point optimization, and evaluation of positioning uncertainty in the central Labrador Sea region: methods, a software tool, and an application. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2015. http://dx.doi.org/10.4095/295859.

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Bidier, S., U. Khristenko, R. Tosi, R. Rossi, and C. Soriano. D7.3 Report on UQ results and overall user experience. Scipedia, 2021. http://dx.doi.org/10.23967/exaqute.2021.9.002.

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This deliverable report focuses on the main Uncertainty Quanti cation (UQ) results obtained within the EXAscale Quanti cation of Uncertainties for Technology and Science Simulation (ExaQUte) project. Details on the turbulent wind inlet generator, that enables the supply of random, yet steady, wind velocity boundary conditions during run-time, are given in section 2. This enables the developed UQ workflow, whose results are presented on the basis of the Commonwealth Advisory Aeronautical Council (CAARC) as described in Deliverable 7.1. Finally, the completed UQ workflow and the results are evaluated from an application-driven wind engineering point of view. Thereby, the significance of the developed methods and the obtained results are discussed and their applicability in practical wind-engineering applications is tested through a complete test-run of the UQ workflow.
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Li, Xiao, GX Xu, FY Ling, ZH Yin, Y. Wei,, Y. Zhao, Xn Li, WC Qi, L. Zhao, and FR Liang. The dose-effect association between electroacupuncture sessions and its effect on chronic migraine: a protocol of a meta-regression of randomized controlled trials. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, December 2022. http://dx.doi.org/10.37766/inplasy2022.12.0085.

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Review question / Objective: We will use a meta-regression approach to verify the dose-effect relationship between the number of electroacupuncture sessions and its effects on migraine. Condition being studied: Migraine is recurrent and chronic, requiring long-term control, but the side effects caused by long-term use limit the use of pharmacotherapy, like non-steroidal anti-inflammatory drugs (NSAIDS), ergoamines and opioids. With fewer side effects and lower cost, acupuncture is becoming a more attractive option for migraine. Relevant studies have confirmed the clinical effects of electroacupuncture on migraine and its effects on intracranial blood flow velocity, functional brain imaging and neuroinflammation. However, uncertainty exists regarding the dose-effect between electroacupuncture and migraine. In recent years, inspired by the dose-effect researches in pharmacology and epidemiology, researches focusing on the dose-effect association between acupuncture and diseases has also begun to emerge. So in this protocol, we designed to use a meta-regression approach to explore the optimal electroacupuncture dose for migraine.
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Stastny, Petr, Robert Roczniok, Daniel Cleather, Martin Musalek, Dominik Novak, and Michal Vagner. Straight speed and acceleration optimal distances and reference values. A systematic review, and meta-analyses. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, May 2022. http://dx.doi.org/10.37766/inplasy2022.5.0010.

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Review question / Objective: To summarize the sprint reference acceleration and speed values for different sprint distances and suggest optimal unification of ice-hockey straight sprint testing. Eligibility criteria: The title and abstract screening was done by two researchers (PS and RR) who selected a set of articles for full text screening, where the inclusion criteria were: 1) male or female ice-hockey players; 2) any cross-sectional or intervention study; 3) tests of ice-hockey sprinting over any distance or any battery of conditioning tests that included straight-line sprints; and, 4) results reported straight-line sprint distance, speed, time, or acceleration. In the case of disagreement between the evaluating authors, the final decision was made by a third author (MV).The full text screening exclusion criteria were: 1) if the article was not in English; 2) the testing did not include straight-line sprinting; 3) the reported values did not include data distribution; 4) the study reported only maximum speed without skating time or average speed; 5) the end of the sprint was defined by the point the player stopped sprinting; 6) the measurement was made with a stopwatch; and, 7) the study had high bias estimation. The maximum speed test was not included due to the uncertain velocity conditions at beginning of testing distance. The bias estimation was performed using the JBI (Joanna Briggs Institute) Critical Appraisal Checklist for Analytical Cross Sectional Studies (supplementary material 1).
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