In this paper, visualization of special features in “The Tale of Genji”, which is a typical Japanese classical literature, is studied by text mining the auxiliary verbs and examining the similarity in the sentence s...In this paper, visualization of special features in “The Tale of Genji”, which is a typical Japanese classical literature, is studied by text mining the auxiliary verbs and examining the similarity in the sentence style by the correspondence analysis with clustering. The result shows that the text mining error in the number of auxiliary verbs can be as small as 15%. The extracted feature in this study supports the multiple authors of “The Tale of Genji”, which agrees well with the result by Murakami and Imanishi [1]. It is also found that extracted features are robust to the text mining error, which suggests that the classification error is less affected by the text mining error and the possible use of this technique for further statistical study in classical literatures.展开更多
This paper deals with the statistical properties of unsteady structure of cavitating water-jet issuing into a stagnant fluid of water using the shadowgraph imaging combined with the proper orthogonal decomposition (PO...This paper deals with the statistical properties of unsteady structure of cavitating water-jet issuing into a stagnant fluid of water using the shadowgraph imaging combined with the proper orthogonal decomposition (POD) analysis. The experimental result indicates that the cavitating jet is composed of axisymmetric mode, while the periodic axial oscillation is found along the jet centerline. The reconstructed cavitation images show the presence of growing, shrinking and shedding motion in the cavitation cloud, which sustains a periodic behavior of the cavitating jet.展开更多
AIM: To determine a species-specific real-time polymerase chain reaction (PCR) assay to detect Pseudomonas aeruginosa (PA),a secondary DNA target for PA that may provide a universal target for other bacterial pathogen...AIM: To determine a species-specific real-time polymerase chain reaction (PCR) assay to detect Pseudomonas aeruginosa (PA),a secondary DNA target for PA that may provide a universal target for other bacterial pathogens,and validate both assays for diagnostic testing.METHODS: PCR detection was established against the ecfX PA gene and the 16S rRNA gene using known PA keratitis isolates.The outcome parameters for both assays were 'limit of detection' (LOD),amplification efficiency (AE),and PAGE amplified product analysis.Both assays were validated against 20 true-positive clinical samples positive for PA DNA and 20 true-negative samples containing no PA DNA.Descriptive statistics and PAGE analysis were used as outcome parameters.RESULTS: AE of the ecfX assay was 96.6%,and LOD was 33.6 copies of target DNA per microliter.AE of the 16S rRNA assay was 103.4%,and LOD was 8.12 copies per microliter.The sensitivity,specificity,positive predictive value,negative predictive value,and efficiency for the ecfX and 16S rRNA assays were [75%,95%,94%,79%,and 85%],and [70%,100%,100%,77%,and 85%],respectively.Both PCR assays were validated,followed by confirmation of DNA patterns from PAGE analysis.CONCLUSION: The PCR methodology described here may be a useful adjunct to standard methods in the diagnosis of PA keratitis.展开更多
Blindness provides an unparalleled opportunity to study plasticity of the nervous system in humans.Seminal work in this area examined the often dramatic modifications to the visual cortex that result when visual input...Blindness provides an unparalleled opportunity to study plasticity of the nervous system in humans.Seminal work in this area examined the often dramatic modifications to the visual cortex that result when visual input is completely absent from birth or very early in life（Kupers and Ptito,2014）.More recent studies explored what happens to the visual pathways in the context of acquired blindness.This is particularly relevant as the majority of diseases that cause vision loss occur in the elderly.展开更多
The purpose of this paper is to understand the mechanism of non-axisymmetric wall-thinning that caused a pipe break in the pipeline of the Mihama nuclear power plant in 2004. The wall thinning was caused by the flow a...The purpose of this paper is to understand the mechanism of non-axisymmetric wall-thinning that caused a pipe break in the pipeline of the Mihama nuclear power plant in 2004. The wall thinning was caused by the flow accelerated corrosion which affects low carbon steel pipelines. The mass transfer rate measurement of the wall thinning behind an office in a curved swirling flow is carried out in a closed-circuit water tunnel using a benzoic acid dissolution method. The experimental results indicate that the high mass transfer rate is observed on one side of the pipe behind the orifice, which is similar to the observation of the wall-thinning rate in the Mihama case. This result suggests that the influence of the secondary flow in the long elbow combined with the swirling flow can produce the non-axisymmetric mass transfer phenomenon behind the orifice.展开更多
The purpose of this paper is to propose a sound localization method as an alternative of the time-resolved particle image velocimetry (PIV) system for detecting the aerodynamic sound source of a circular cylinder in a...The purpose of this paper is to propose a sound localization method as an alternative of the time-resolved particle image velocimetry (PIV) system for detecting the aerodynamic sound source of a circular cylinder in a uniform flow. The sound source intensity of a circular cylinder in a uniform flow is evaluated by measuring the time-derivative of instantaneous velocity field in the flow field using a pair of planar PIV system. It allows the visualization of the sound source intensity distribution, which is the time-derivative of the vector product of vorticity and velocity. The experimental results indicate that the aerodynamic sound is generated from the separation point and the velocity fluctuation in the separating shear layer from the circular cylinder. These results agree qualitatively with the previous findings from experiment and numerical simulation, which supports the validity of the present experimental method for evaluating the sound source intensity distribution.展开更多
This paper describes the experimental method for evaluating the flight trajectory and the aerodynamic performance of a kicked non-spinning soccer ball. The flight trajectory measurement is carried out using the digita...This paper describes the experimental method for evaluating the flight trajectory and the aerodynamic performance of a kicked non-spinning soccer ball. The flight trajectory measurement is carried out using the digital image analysis. A centroid method and a template matching method are tested for the flight trajectory analysis using the artificial images generated by the data of a free-fall experiment. The drag coefficient obtained by the centroid method is better suited for the sports ball experiment than that by the template matching method, which is due to the robustness of the centroid method to the non-uniform illumination. Then, the flight trajectory analysis is introduced to a kicked experiment for a non-spinning soccer ball. The experimental result obtained from the stereo observation indicates that the S-shaped variation is found in the three-dimensional flight trajectory and in the side force coefficient during the flight of the non-spinning soccer ball.展开更多
This paper describes the experimental study of viscosity measurement error in the vibrational type viscometer, which measures viscous damping of the oscillating circular plate in a fluid in continuously increasing tem...This paper describes the experimental study of viscosity measurement error in the vibrational type viscometer, which measures viscous damping of the oscillating circular plate in a fluid in continuously increasing temperatures. The experiments are carried out to measure non-uniformity of the temperature field in the test cup of the vibrational viscometer in continuously increasing temperatures, while changing the viscosity of the target fluids. Experimental outcomes show that non-uniformity of the temperature grows in the cup and results in viscosity measurement error, when the viscosity of the fluid increases. In order to understand this phenomenon, velocity measurement by particle image velocimetry is conducted in the test cup for fluids of varying viscosity. The results indicate that mixing is enhanced in the low-viscosity fluid by the occurrence of unsteady thermal convection, while weaker convection appears in the high-viscosity fluid.展开更多
The purpose of this study was to clarify grid convergence property of three-dimensional measurement-integrated (3D-MI) simulation for a flow behind a square cylinder with Karman vortex street. Measurement-integrated (...The purpose of this study was to clarify grid convergence property of three-dimensional measurement-integrated (3D-MI) simulation for a flow behind a square cylinder with Karman vortex street. Measurement-integrated (MI) simulation is a kind of the observer in the dynamical system theory by using CFD scheme as a mathematical model of the system. In a former study, two-dimensional MI (2D-MI) simulation with a coarse grid system showed a fairly good result in comparison with a 2D ordinary (2D-O) simulation, but the results were degraded with grid refinement. In this study, 3D-MI simulation and three-dimensional ordinary (3D-O) simulation were performed with three grid systems of different grid resolutions, and their grid convergence properties were compared. As a result, all 3D-MI simulations reproduced the vortex shedding frequency identical to that of the experiment, and the flow fields obtained were very close, within 5% difference between the results, while the results of the 3D-O simulations showed variation of the solution under convergence. It is shown that the grid convergence property of 3D-MI simulation is monotonic and better than that of 3D-O simulation, whereas those of 2D-O and 2D-MI simulations for streamwise velocity fluctuation are divergent. The solution of 3D-MI simulation with a relatively coarse grid system properly reproduces the basic three-dimensional structure of the wake flow as well as the drag and lift coefficients.展开更多
In this paper, the measurement of an aerodynamic sound source for a semi-circular cylinder in a uniform flow is described using Particle Image Velocimetry (PIV). This experimental technique is based on vortex sound th...In this paper, the measurement of an aerodynamic sound source for a semi-circular cylinder in a uniform flow is described using Particle Image Velocimetry (PIV). This experimental technique is based on vortex sound theory, where the time derivative of vorticity is evaluated with the aid of two sets of standard PIV systems. The experimental results indicate that the sound source for the semi-circular cylinder is located around the shear layer near the edge of the semi-circular cylinder. The sound source intensity and the area are reduced in the semi-circular cylinder compared with those of a circular cylinder. This result indicates that the aerodynamic sound of the semi- circular cylinder is smaller than that of the circular cylinder, which supports the microphone measurement result.展开更多
Aeolian tone from a semi-circular cylinder in a uniform flow is studied experimentally for various angles of attack. It is found that the peak sound spectrum of the Aeolian tone from the semi-circular cylinder is smal...Aeolian tone from a semi-circular cylinder in a uniform flow is studied experimentally for various angles of attack. It is found that the peak sound spectrum of the Aeolian tone from the semi-circular cylinder is smaller than that from the circular cylinder and the lowest sound is observed around the zero angle of attack. This is due to the reduction in the fluctuating lift force on the semi-circular cylinder compared to that of the circular cylinder. This result suggests the validity of the analogy between the sound pressure level and the fluctuating lift force on a semi-circular cylinder in a stream. The flow visualization study also supports these results.展开更多
Background In recent decades,unmanned aerial vehicles(UAVs)have developed rapidly and been widely applied in many domains,including photography,reconstruction,monitoring,and search and rescue.In such applications,one ...Background In recent decades,unmanned aerial vehicles(UAVs)have developed rapidly and been widely applied in many domains,including photography,reconstruction,monitoring,and search and rescue.In such applications,one key issue is path and view planning,which tells UAVs exactly where to fly and how to search.Methods With specific consideration for three popular UAV applications(scene reconstruction,environment exploration,and aerial cinematography),we present a survey that should assist researchers in positioning and evaluating their works in the context of existing solutions.Results/Conclusions It should also help newcomers and practitioners in related fields quickly gain an overview of the vast literature.In addition to the current research status,we analyze and elaborate on advantages,disadvantages,and potential explorative trends for each application domain.展开更多
Dynamic Mode Decomposition(DMD)is a data-driven and model-free decomposition technique.It is suitable for revealing spatio-temporal features of both numerically and experimentally acquired data.Conceptually,DMD perfor...Dynamic Mode Decomposition(DMD)is a data-driven and model-free decomposition technique.It is suitable for revealing spatio-temporal features of both numerically and experimentally acquired data.Conceptually,DMD performs a low-dimensional spectral decomposition of the data into the following components:the modes,called DMD modes,encode the spatial contribution of the decomposition,whereas the DMD amplitudes specify their impact.Each associated eigenvalue,referred to as DMD eigenvalue,characterizes the frequency and growth rate of the DMD mode.In this paper,we demonstrate how the components of DMD can be utilized to obtain temporal and spatial information from time-dependent flow fields.We begin with the theoretical background of DMD and its application to unsteady flow.Next,we examine the conventional process with DMD mathematically and put it in relationship to the discrete Fourier transform.Our analysis shows that the current use of DMD components has several drawbacks.To resolve these problems we adjust the components and provide new and meaningful insights into the decomposition:we show that our improved components capture the spatio-temporal patterns of the flow better.Moreover,we remove redundancies in the decomposition and clarify the interplay between components,allowing users to understand the impact of components.These new representations,which respect the spatio-temporal character of DMD,enable two clustering methods that segment the flow into physically relevant sections and can therefore be used for the selection of DMD components.With a number of typical examples,we demonstrate that the combination of these techniques allows new insights with DMD for unsteady flow.展开更多
Importance. Medical images are essential for modern medicine and an important research subject in visualization. However,medical experts are often not aware of the many advanced three-dimensional (3D) medical image vi...Importance. Medical images are essential for modern medicine and an important research subject in visualization. However,medical experts are often not aware of the many advanced three-dimensional (3D) medical image visualization techniques thatcould increase their capabilities in data analysis and assist the decision-making process for specific medical problems. Ourpaper provides a review of 3D visualization techniques for medical images, intending to bridge the gap between medicalexperts and visualization researchers. Highlights. Fundamental visualization techniques are revisited for various medicalimaging modalities, from computational tomography to diffusion tensor imaging, featuring techniques that enhance spatialperception, which is critical for medical practices. The state-of-the-art of medical visualization is reviewed based on aprocedure-oriented classification of medical problems for studies of individuals and populations. This paper summarizes freesoftware tools for different modalities of medical images designed for various purposes, including visualization, analysis, andsegmentation, and it provides respective Internet links. Conclusions. Visualization techniques are a useful tool for medicalexperts to tackle specific medical problems in their daily work. Our review provides a quick reference to such techniques giventhe medical problem and modalities of associated medical images. We summarize fundamental techniques and readily availablevisualization tools to help medical experts to better understand and utilize medical imaging data. This paper could contributeto the joint effort of the medical and visualization communities to advance precision medicine.展开更多
Importance:Narrative medicine(NM),in which patient stories play a crucial role in their diagnosis and treatment,can potentially support a more holistic approach to patient care than traditional scientiffc ones.However...Importance:Narrative medicine(NM),in which patient stories play a crucial role in their diagnosis and treatment,can potentially support a more holistic approach to patient care than traditional scientiffc ones.However,there are some challenges in the implementation of narrative medicine,for example,differences in understanding illnesses between physicians and patients and physicians’increased workloads and overloaded schedules.This paper ffrst presents a review to explore previous visualization research for narrative medicine to bridge the gap between visualization researchers and narrative medicine experts and explore further visualization opportunities.Highlights:The review is conducted from 2 perspectives:(a)the contexts and domains in which visualization has been explored for narrative medicine and(b)the forms and solutions applied in these studies.Four applied domains are deffned,including understanding patients from narrative records,medical communication,medical conversation training in education,and psychotherapy and emotional wellness enhancement.Conclusions:A future work framework illustrates some opportunities for future research,including groups of speciffc directions and future points for the 4 domains and 3 technological exploration opportunities(combination of narrative and medical data visualization,taskaudience-based visual storytelling,and user-centered interactive visualization).Speciffcally,3 directions of future work in medical communication(asynchronous online physician-patient communication,synchronous face-to-face medical conversation,and medical knowledge dissemination)were concluded.展开更多
Active vision is inherently attention-driven:an agent actively selects views to attend in order to rapidly perform a vision task while improving its internal representation of the scene being observed.Inspired by the ...Active vision is inherently attention-driven:an agent actively selects views to attend in order to rapidly perform a vision task while improving its internal representation of the scene being observed.Inspired by the recent success of attention-based models in 2D vision tasks based on single RGB images, we address multi-view depth-based active object recognition using an attention mechanism, by use of an end-to-end recurrent 3D attentional network. The architecture takes advantage of a recurrent neural network to store and update an internal representation. Our model,trained with 3D shape datasets, is able to iteratively attend the best views targeting an object of interest for recognizing it. To realize 3D view selection, we derive a 3D spatial transformer network. It is dierentiable,allowing training with backpropagation, and so achieving much faster convergence than the reinforcement learning employed by most existing attention-based models. Experiments show that our method, with only depth input, achieves state-of-the-art next-best-view performance both in terms of time taken and recognition accuracy.展开更多
Dimensionality reduction is often used to project time series data from multidimensional to two-dimensional space to generate visual representations of the temporal evolution.In this context,we address the problem of ...Dimensionality reduction is often used to project time series data from multidimensional to two-dimensional space to generate visual representations of the temporal evolution.In this context,we address the problem of multidimensional time series visualization by presenting a new method to show and handle projection errors introduced by dimensionality reduction techniques on multidimensional temporal data.For visualization,subsequent time instances are rendered as dots that are connected by lines or curves to indicate the temporal dependencies.However,inevitable projection artifacts may lead to poor visualization quality and misinterpretation of the temporal information.Wrongly projected data points,inaccurate variations in the distances between projected time instances,and intersections of connecting lines could lead to wrong assumptions about the original data.We adapt local and global quality metrics to measure the visual quality along the projected time series,and we introduce a model to assess the projection error at intersecting lines.These serve as a basis for our new uncertainty visualization techniques that use different visual encodings and interactions to indicate,communicate,and work with the visualization uncertainty from projection errors and artifacts along the timeline of data points,their connections,and intersections.Our approach is agnostic to the projection method and works for linear and non-linear dimensionality reduction methods alike.展开更多
We present angle-uniform parallel coordinates,a data-independent technique that deforms the image plane of parallel coordinates so that the angles of linear relationships between two variables are linearly mapped alon...We present angle-uniform parallel coordinates,a data-independent technique that deforms the image plane of parallel coordinates so that the angles of linear relationships between two variables are linearly mapped along the horizontal axis of the parallel coordinates plot.Despite being a common method for visualizing multidimensional data,parallel coordinates are ineffective for revealing positive correlations since the associated parallel coordinates points of such structures may be located at infinity in the image plane and the asymmetric encoding of negative and positive correlations may lead to unreliable estimations.To address this issue,we introduce a transformation that bounds all points horizontally using an angleuniform mapping and shrinks them vertically in a structure-preserving fashion;polygonal lines become smooth curves and a symmetric representation of data correlations is achieved.We further propose a combined subsampling and density visualization approach to reduce visual clutter caused by overdrawing.Our method enables accurate visual pattern interpretation of data correlations,and its data-independent nature makes it applicable to all multidimensional datasets.The usefulness of our method is demonstrated using examples of synthetic and real-world datasets.展开更多
We investigate task performance and reading characteristics for scatterplots(Cartesian coordinates)and parallel coordinates.In a controlled eye-tracking study,we asked 24 participants to assess the relative distance o...We investigate task performance and reading characteristics for scatterplots(Cartesian coordinates)and parallel coordinates.In a controlled eye-tracking study,we asked 24 participants to assess the relative distance of points in multidimensional space,depending on the diagram type(parallel coordinates or a horizontal collection of scatterplots),the number of data dimensions(2,4,6,or 8),and the relative distance between points(15%,20%,or 25%).For a given reference point and two target points,we instructed participants to choose the target point that was closer to the reference point in multidimensional space.We present a visual scanning model that describes different strategies to solve this retrieval task for both diagram types,and propose corresponding hypotheses that we test using task completion time,accuracy,and gaze positions as dependent variables.Our results show that scatterplots outperform parallel coordinates significantly in 2 dimensions,however,the task was solved more quickly and more accurately with parallel coordinates in 8 dimensions.The eye-tracking data further shows significant differences between Cartesian and parallel coordinates,as well as between different numbers of dimensions.For parallel coordinates,there is a clear trend toward shorter fixations and longer saccades with increasing number of dimensions.Using an area-of-interest(AOI)based approach,we identify different reading strategies for each diagram type:For parallel coordinates,the participants’gaze frequently jumped back and forth between pairs of axes,while axes were rarely focused on when viewing Cartesian coordinates.We further found that participants’attention is biased:toward the center of the whole plot for parallel coordinates and skewed to the center/left side for Cartesian coordinates.We anticipate that these results may support the design of more effective visualizations for multidimensional data.展开更多
文摘In this paper, visualization of special features in “The Tale of Genji”, which is a typical Japanese classical literature, is studied by text mining the auxiliary verbs and examining the similarity in the sentence style by the correspondence analysis with clustering. The result shows that the text mining error in the number of auxiliary verbs can be as small as 15%. The extracted feature in this study supports the multiple authors of “The Tale of Genji”, which agrees well with the result by Murakami and Imanishi [1]. It is also found that extracted features are robust to the text mining error, which suggests that the classification error is less affected by the text mining error and the possible use of this technique for further statistical study in classical literatures.
文摘This paper deals with the statistical properties of unsteady structure of cavitating water-jet issuing into a stagnant fluid of water using the shadowgraph imaging combined with the proper orthogonal decomposition (POD) analysis. The experimental result indicates that the cavitating jet is composed of axisymmetric mode, while the periodic axial oscillation is found along the jet centerline. The reconstructed cavitation images show the presence of growing, shrinking and shedding motion in the cavitation cloud, which sustains a periodic behavior of the cavitating jet.
基金Supported by The Pennsylvania Lions Club and The Charles T. Campbell Foundation. A core grant for Vision Research NIH EY008098 provided expertise within the molecular moduleResearch to Prevent Blindness has provided continued support of the ophthalmology department
文摘AIM: To determine a species-specific real-time polymerase chain reaction (PCR) assay to detect Pseudomonas aeruginosa (PA),a secondary DNA target for PA that may provide a universal target for other bacterial pathogens,and validate both assays for diagnostic testing.METHODS: PCR detection was established against the ecfX PA gene and the 16S rRNA gene using known PA keratitis isolates.The outcome parameters for both assays were 'limit of detection' (LOD),amplification efficiency (AE),and PAGE amplified product analysis.Both assays were validated against 20 true-positive clinical samples positive for PA DNA and 20 true-negative samples containing no PA DNA.Descriptive statistics and PAGE analysis were used as outcome parameters.RESULTS: AE of the ecfX assay was 96.6%,and LOD was 33.6 copies of target DNA per microliter.AE of the 16S rRNA assay was 103.4%,and LOD was 8.12 copies per microliter.The sensitivity,specificity,positive predictive value,negative predictive value,and efficiency for the ecfX and 16S rRNA assays were [75%,95%,94%,79%,and 85%],and [70%,100%,100%,77%,and 85%],respectively.Both PCR assays were validated,followed by confirmation of DNA patterns from PAGE analysis.CONCLUSION: The PCR methodology described here may be a useful adjunct to standard methods in the diagnosis of PA keratitis.
基金supported by National Institutes of Health Contracts P30-EY008098 and T32-EY017271-06(BethesdaMD)+14 种基金United States Department of Defense DM090217(ArlingtonVA)Alcon Research Institute Young Investigator Grant(Fort WorthTX)Eye and Ear Foundation(PittsburghPA)Research to Prevent Blindness(New YorkNY)Aging Institute Pilot Seed GrantUniversity of Pittsburgh(PittsburghPA)Postdoctoral Fellowship Program in Ocular Tissue Engineering and Regenerative OphthalmologyLouis J.Fox Center for Vision RestorationUniversity of Pittsburgh and UPMC(PittsburghPA)
文摘Blindness provides an unparalleled opportunity to study plasticity of the nervous system in humans.Seminal work in this area examined the often dramatic modifications to the visual cortex that result when visual input is completely absent from birth or very early in life（Kupers and Ptito,2014）.More recent studies explored what happens to the visual pathways in the context of acquired blindness.This is particularly relevant as the majority of diseases that cause vision loss occur in the elderly.
文摘The purpose of this paper is to understand the mechanism of non-axisymmetric wall-thinning that caused a pipe break in the pipeline of the Mihama nuclear power plant in 2004. The wall thinning was caused by the flow accelerated corrosion which affects low carbon steel pipelines. The mass transfer rate measurement of the wall thinning behind an office in a curved swirling flow is carried out in a closed-circuit water tunnel using a benzoic acid dissolution method. The experimental results indicate that the high mass transfer rate is observed on one side of the pipe behind the orifice, which is similar to the observation of the wall-thinning rate in the Mihama case. This result suggests that the influence of the secondary flow in the long elbow combined with the swirling flow can produce the non-axisymmetric mass transfer phenomenon behind the orifice.
文摘The purpose of this paper is to propose a sound localization method as an alternative of the time-resolved particle image velocimetry (PIV) system for detecting the aerodynamic sound source of a circular cylinder in a uniform flow. The sound source intensity of a circular cylinder in a uniform flow is evaluated by measuring the time-derivative of instantaneous velocity field in the flow field using a pair of planar PIV system. It allows the visualization of the sound source intensity distribution, which is the time-derivative of the vector product of vorticity and velocity. The experimental results indicate that the aerodynamic sound is generated from the separation point and the velocity fluctuation in the separating shear layer from the circular cylinder. These results agree qualitatively with the previous findings from experiment and numerical simulation, which supports the validity of the present experimental method for evaluating the sound source intensity distribution.
文摘This paper describes the experimental method for evaluating the flight trajectory and the aerodynamic performance of a kicked non-spinning soccer ball. The flight trajectory measurement is carried out using the digital image analysis. A centroid method and a template matching method are tested for the flight trajectory analysis using the artificial images generated by the data of a free-fall experiment. The drag coefficient obtained by the centroid method is better suited for the sports ball experiment than that by the template matching method, which is due to the robustness of the centroid method to the non-uniform illumination. Then, the flight trajectory analysis is introduced to a kicked experiment for a non-spinning soccer ball. The experimental result obtained from the stereo observation indicates that the S-shaped variation is found in the three-dimensional flight trajectory and in the side force coefficient during the flight of the non-spinning soccer ball.
文摘This paper describes the experimental study of viscosity measurement error in the vibrational type viscometer, which measures viscous damping of the oscillating circular plate in a fluid in continuously increasing temperatures. The experiments are carried out to measure non-uniformity of the temperature field in the test cup of the vibrational viscometer in continuously increasing temperatures, while changing the viscosity of the target fluids. Experimental outcomes show that non-uniformity of the temperature grows in the cup and results in viscosity measurement error, when the viscosity of the fluid increases. In order to understand this phenomenon, velocity measurement by particle image velocimetry is conducted in the test cup for fluids of varying viscosity. The results indicate that mixing is enhanced in the low-viscosity fluid by the occurrence of unsteady thermal convection, while weaker convection appears in the high-viscosity fluid.
文摘The purpose of this study was to clarify grid convergence property of three-dimensional measurement-integrated (3D-MI) simulation for a flow behind a square cylinder with Karman vortex street. Measurement-integrated (MI) simulation is a kind of the observer in the dynamical system theory by using CFD scheme as a mathematical model of the system. In a former study, two-dimensional MI (2D-MI) simulation with a coarse grid system showed a fairly good result in comparison with a 2D ordinary (2D-O) simulation, but the results were degraded with grid refinement. In this study, 3D-MI simulation and three-dimensional ordinary (3D-O) simulation were performed with three grid systems of different grid resolutions, and their grid convergence properties were compared. As a result, all 3D-MI simulations reproduced the vortex shedding frequency identical to that of the experiment, and the flow fields obtained were very close, within 5% difference between the results, while the results of the 3D-O simulations showed variation of the solution under convergence. It is shown that the grid convergence property of 3D-MI simulation is monotonic and better than that of 3D-O simulation, whereas those of 2D-O and 2D-MI simulations for streamwise velocity fluctuation are divergent. The solution of 3D-MI simulation with a relatively coarse grid system properly reproduces the basic three-dimensional structure of the wake flow as well as the drag and lift coefficients.
文摘In this paper, the measurement of an aerodynamic sound source for a semi-circular cylinder in a uniform flow is described using Particle Image Velocimetry (PIV). This experimental technique is based on vortex sound theory, where the time derivative of vorticity is evaluated with the aid of two sets of standard PIV systems. The experimental results indicate that the sound source for the semi-circular cylinder is located around the shear layer near the edge of the semi-circular cylinder. The sound source intensity and the area are reduced in the semi-circular cylinder compared with those of a circular cylinder. This result indicates that the aerodynamic sound of the semi- circular cylinder is smaller than that of the circular cylinder, which supports the microphone measurement result.
文摘Aeolian tone from a semi-circular cylinder in a uniform flow is studied experimentally for various angles of attack. It is found that the peak sound spectrum of the Aeolian tone from the semi-circular cylinder is smaller than that from the circular cylinder and the lowest sound is observed around the zero angle of attack. This is due to the reduction in the fluctuating lift force on the semi-circular cylinder compared to that of the circular cylinder. This result suggests the validity of the analogy between the sound pressure level and the fluctuating lift force on a semi-circular cylinder in a stream. The flow visualization study also supports these results.
基金LHTD(20170003)and the Guangdong Laboratory of Artificial Intelligence and Digital Economy(SZ).
文摘Background In recent decades,unmanned aerial vehicles(UAVs)have developed rapidly and been widely applied in many domains,including photography,reconstruction,monitoring,and search and rescue.In such applications,one key issue is path and view planning,which tells UAVs exactly where to fly and how to search.Methods With specific consideration for three popular UAV applications(scene reconstruction,environment exploration,and aerial cinematography),we present a survey that should assist researchers in positioning and evaluating their works in the context of existing solutions.Results/Conclusions It should also help newcomers and practitioners in related fields quickly gain an overview of the vast literature.In addition to the current research status,we analyze and elaborate on advantages,disadvantages,and potential explorative trends for each application domain.
文摘Dynamic Mode Decomposition(DMD)is a data-driven and model-free decomposition technique.It is suitable for revealing spatio-temporal features of both numerically and experimentally acquired data.Conceptually,DMD performs a low-dimensional spectral decomposition of the data into the following components:the modes,called DMD modes,encode the spatial contribution of the decomposition,whereas the DMD amplitudes specify their impact.Each associated eigenvalue,referred to as DMD eigenvalue,characterizes the frequency and growth rate of the DMD mode.In this paper,we demonstrate how the components of DMD can be utilized to obtain temporal and spatial information from time-dependent flow fields.We begin with the theoretical background of DMD and its application to unsteady flow.Next,we examine the conventional process with DMD mathematically and put it in relationship to the discrete Fourier transform.Our analysis shows that the current use of DMD components has several drawbacks.To resolve these problems we adjust the components and provide new and meaningful insights into the decomposition:we show that our improved components capture the spatio-temporal patterns of the flow better.Moreover,we remove redundancies in the decomposition and clarify the interplay between components,allowing users to understand the impact of components.These new representations,which respect the spatio-temporal character of DMD,enable two clustering methods that segment the flow into physically relevant sections and can therefore be used for the selection of DMD components.With a number of typical examples,we demonstrate that the combination of these techniques allows new insights with DMD for unsteady flow.
基金the Data for Better Health Project of Peking University-Master Kong and by NIH(R01 EB031872).
文摘Importance. Medical images are essential for modern medicine and an important research subject in visualization. However,medical experts are often not aware of the many advanced three-dimensional (3D) medical image visualization techniques thatcould increase their capabilities in data analysis and assist the decision-making process for specific medical problems. Ourpaper provides a review of 3D visualization techniques for medical images, intending to bridge the gap between medicalexperts and visualization researchers. Highlights. Fundamental visualization techniques are revisited for various medicalimaging modalities, from computational tomography to diffusion tensor imaging, featuring techniques that enhance spatialperception, which is critical for medical practices. The state-of-the-art of medical visualization is reviewed based on aprocedure-oriented classification of medical problems for studies of individuals and populations. This paper summarizes freesoftware tools for different modalities of medical images designed for various purposes, including visualization, analysis, andsegmentation, and it provides respective Internet links. Conclusions. Visualization techniques are a useful tool for medicalexperts to tackle specific medical problems in their daily work. Our review provides a quick reference to such techniques giventhe medical problem and modalities of associated medical images. We summarize fundamental techniques and readily availablevisualization tools to help medical experts to better understand and utilize medical imaging data. This paper could contributeto the joint effort of the medical and visualization communities to advance precision medicine.
基金funded by NSFC 62272012,Wuhan East Lake High-Tech Development Zone(also known as the Optics Valley of China,or OVC)National Comprehensive Experimental Base for Governance of Intelligent Society.
文摘Importance:Narrative medicine(NM),in which patient stories play a crucial role in their diagnosis and treatment,can potentially support a more holistic approach to patient care than traditional scientiffc ones.However,there are some challenges in the implementation of narrative medicine,for example,differences in understanding illnesses between physicians and patients and physicians’increased workloads and overloaded schedules.This paper ffrst presents a review to explore previous visualization research for narrative medicine to bridge the gap between visualization researchers and narrative medicine experts and explore further visualization opportunities.Highlights:The review is conducted from 2 perspectives:(a)the contexts and domains in which visualization has been explored for narrative medicine and(b)the forms and solutions applied in these studies.Four applied domains are deffned,including understanding patients from narrative records,medical communication,medical conversation training in education,and psychotherapy and emotional wellness enhancement.Conclusions:A future work framework illustrates some opportunities for future research,including groups of speciffc directions and future points for the 4 domains and 3 technological exploration opportunities(combination of narrative and medical data visualization,taskaudience-based visual storytelling,and user-centered interactive visualization).Speciffcally,3 directions of future work in medical communication(asynchronous online physician-patient communication,synchronous face-to-face medical conversation,and medical knowledge dissemination)were concluded.
基金supported by National Natural Science Foundation of China (Nos. 61572507, 61622212, and 61532003)supported by the China Scholarship Council
文摘Active vision is inherently attention-driven:an agent actively selects views to attend in order to rapidly perform a vision task while improving its internal representation of the scene being observed.Inspired by the recent success of attention-based models in 2D vision tasks based on single RGB images, we address multi-view depth-based active object recognition using an attention mechanism, by use of an end-to-end recurrent 3D attentional network. The architecture takes advantage of a recurrent neural network to store and update an internal representation. Our model,trained with 3D shape datasets, is able to iteratively attend the best views targeting an object of interest for recognizing it. To realize 3D view selection, we derive a 3D spatial transformer network. It is dierentiable,allowing training with backpropagation, and so achieving much faster convergence than the reinforcement learning employed by most existing attention-based models. Experiments show that our method, with only depth input, achieves state-of-the-art next-best-view performance both in terms of time taken and recognition accuracy.
基金Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under Germany’s Excellence Strategy–EXC-2075–390740016.
文摘Dimensionality reduction is often used to project time series data from multidimensional to two-dimensional space to generate visual representations of the temporal evolution.In this context,we address the problem of multidimensional time series visualization by presenting a new method to show and handle projection errors introduced by dimensionality reduction techniques on multidimensional temporal data.For visualization,subsequent time instances are rendered as dots that are connected by lines or curves to indicate the temporal dependencies.However,inevitable projection artifacts may lead to poor visualization quality and misinterpretation of the temporal information.Wrongly projected data points,inaccurate variations in the distances between projected time instances,and intersections of connecting lines could lead to wrong assumptions about the original data.We adapt local and global quality metrics to measure the visual quality along the projected time series,and we introduce a model to assess the projection error at intersecting lines.These serve as a basis for our new uncertainty visualization techniques that use different visual encodings and interactions to indicate,communicate,and work with the visualization uncertainty from projection errors and artifacts along the timeline of data points,their connections,and intersections.Our approach is agnostic to the projection method and works for linear and non-linear dimensionality reduction methods alike.
基金support from the Data for Better Health Project of Peking University-Master Kong,YW from the National Natural Science Foundation of China(62132017)DW from the Deutsche Forschungsgemeinschaft(DFG)Project-ID 251654672-TRR 161.
文摘We present angle-uniform parallel coordinates,a data-independent technique that deforms the image plane of parallel coordinates so that the angles of linear relationships between two variables are linearly mapped along the horizontal axis of the parallel coordinates plot.Despite being a common method for visualizing multidimensional data,parallel coordinates are ineffective for revealing positive correlations since the associated parallel coordinates points of such structures may be located at infinity in the image plane and the asymmetric encoding of negative and positive correlations may lead to unreliable estimations.To address this issue,we introduce a transformation that bounds all points horizontally using an angleuniform mapping and shrinks them vertically in a structure-preserving fashion;polygonal lines become smooth curves and a symmetric representation of data correlations is achieved.We further propose a combined subsampling and density visualization approach to reduce visual clutter caused by overdrawing.Our method enables accurate visual pattern interpretation of data correlations,and its data-independent nature makes it applicable to all multidimensional datasets.The usefulness of our method is demonstrated using examples of synthetic and real-world datasets.
基金We would like to thank the Carl-Zeiss-Foundation(Carl-Zeiss-Stiftung)the German Research Foundation(DFG)for financial support within project B01 of SFB/Transregio 161.
文摘We investigate task performance and reading characteristics for scatterplots(Cartesian coordinates)and parallel coordinates.In a controlled eye-tracking study,we asked 24 participants to assess the relative distance of points in multidimensional space,depending on the diagram type(parallel coordinates or a horizontal collection of scatterplots),the number of data dimensions(2,4,6,or 8),and the relative distance between points(15%,20%,or 25%).For a given reference point and two target points,we instructed participants to choose the target point that was closer to the reference point in multidimensional space.We present a visual scanning model that describes different strategies to solve this retrieval task for both diagram types,and propose corresponding hypotheses that we test using task completion time,accuracy,and gaze positions as dependent variables.Our results show that scatterplots outperform parallel coordinates significantly in 2 dimensions,however,the task was solved more quickly and more accurately with parallel coordinates in 8 dimensions.The eye-tracking data further shows significant differences between Cartesian and parallel coordinates,as well as between different numbers of dimensions.For parallel coordinates,there is a clear trend toward shorter fixations and longer saccades with increasing number of dimensions.Using an area-of-interest(AOI)based approach,we identify different reading strategies for each diagram type:For parallel coordinates,the participants’gaze frequently jumped back and forth between pairs of axes,while axes were rarely focused on when viewing Cartesian coordinates.We further found that participants’attention is biased:toward the center of the whole plot for parallel coordinates and skewed to the center/left side for Cartesian coordinates.We anticipate that these results may support the design of more effective visualizations for multidimensional data.
