Multiple single-point imaging (mSPI) as a tool for capturing and characterizing MR signals and repetitive signal disturbances with high temporal resolution: The MRI scanner as a high-speed camera

2013 ◽  
Vol 31 (7) ◽  
pp. 1037-1043 ◽  
Author(s):  
Chris J.G. Bakker ◽  
Jetse S. van Gorp ◽  
Jan L. Verwoerd ◽  
Albert H. Westra ◽  
Job G. Bouwman ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
High Speed ◽  
Single Point ◽  
High Temporal Resolution ◽  
High Speed Camera

scholarly journals When does a granular material behave like a continuum fluid?

2012 ◽  
Vol 704 ◽  
pp. 1-4 ◽  
Author(s):  
John R. de Bruyn
Keyword(s):  
Granular Material ◽  
Temporal Resolution ◽  
High Speed ◽  
High Impact ◽  
High Temporal Resolution ◽  
Granular Bed ◽  
Fluid Limit ◽  
High Speed Imaging ◽  
Impact Energies ◽  
The Impact

AbstractA flowing granular material can behave like a collection of individual interacting grains or like a continuum fluid, depending in large part on the energy imparted to the grains. As yet, however, we have no general understanding of how or under what conditions the fluid limit is reached. Marston, Li & Thoroddsen (J. Fluid Mech., this issue, vol. 704, 2012, pp. 5–36) use high-speed imaging to investigate the ejection of grains from a granular bed due to the impact of a spherical projectile. Their high temporal resolution allows them to study the very fast processes that take place immediately following the impact. They demonstrate that for very fine grains and high impact energies, the dynamics of the ejecta is both qualitatively and quantitatively similar to what is seen in analogous experiments with fluid targets.

Capture of Shear Crack Propagation in Metallic Glass by High-Speed Camera and In Situ SEM

2014 ◽  
Vol 626 ◽  
pp. 162-170 ◽  
Author(s):  
Bing Hou ◽  
Meng Zhao ◽  
Pei Yang ◽  
Yu Long Li
Keyword(s):  
Metallic Glass ◽  
High Speed ◽  
Shear Crack ◽  
Shear Bands ◽  
High Temporal Resolution ◽  
High Speed Camera ◽  
Stress Curve ◽  
Split Hopkinson ◽  
Split Hopkinson Pressure Bars

The dynamic double-notched experiments by using Split Hopkinson Pressure Bars (SHPB) and high-speed camera were performed on bulk metallic glass. In the double-notched experiment, shear crack propagating process was captured with the high temporal resolution of high-speed camera and the crack front propagating velocity was estimated to be 1137m/s. the shear strain/shear stress curve of BMG under dynamic loading was also obtained. Static in-situ SEM tensile experiments were included to study the multiple shear bands propagating behavior on a glassy ribbon. It was found that shear bands propagates progressively in an intermittent and discontinuous manner, and the choice of which shear bands to propagate and which ones to keep still among multiple shear bands is quite stochastic. This is explained qualitatively from the view point of energy.

scholarly journals Sub-millisecond 2D MRI of the vocal fold oscillation using single-point imaging with rapid encoding

2021 ◽  
Author(s):  
Johannes Fischer ◽  
Ali Caglar Özen ◽  
Serhat Ilbey ◽  
Louisa Traser ◽  
Matthias Echternach ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Vocal Fold ◽  
Single Point ◽  
Image Data ◽  
Vocal Folds ◽  
High Temporal Resolution ◽  
Two Dimensional ◽  
Phase Encoding ◽  
Motion Phantom ◽  
First Time

Abstract Objective The slow spatial encoding of MRI has precluded its application to rapid physiologic motion in the past. The purpose of this study is to introduce a new fast acquisition method and to demonstrate feasibility of encoding rapid two-dimensional motion of human vocal folds with sub-millisecond resolution. Method In our previous work, we achieved high temporal resolution by applying a rapidly switched phase encoding gradient along the direction of motion. In this work, we extend phase encoding to the second image direction by using single-point imaging with rapid encoding (SPIRE) to image the two-dimensional vocal fold oscillation in the coronal view. Image data were gated using electroglottography (EGG) and motion corrected. An iterative reconstruction with a total variation (TV) constraint was used and the sequence was also simulated using a motion phantom. Results Dynamic images of the vocal folds during phonation at pitches of 150 and 165 Hz were acquired in two volunteers and the periodic motion of the vocal folds at a temporal resolution of about 600 µs was shown. The simulations emphasize the necessity of SPIRE for two-dimensional motion encoding. Discussion SPIRE is a new MRI method to image rapidly oscillating structures and for the first time provides dynamic images of the vocal folds oscillations in the coronal plane.

scholarly journals Observation resolution critically influences movement-based foraging indices

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Michael Kalyuzhny ◽  
Tom Haran ◽  
Dror Hawlena
Keyword(s):  
Foraging Behavior ◽  
Temporal Resolution ◽  
High Speed ◽  
Original Data ◽  
Field Observations ◽  
High Speed Camera ◽  
Movement Sequences ◽  
Order Of Magnitude

Abstract Movement‐based indices such as moves per minute (MPM) and proportion time moving (PTM) are common methodologies to quantify foraging behavior. Hundreds of studies have reported these indices, many without specifying the temporal resolution of their original data, and others using varying resolutions. This was done despite the likelihood that observation resolution can affect MPM and PTM estimates. Our goal was to empirically determine the sensitivity of these foraging indices to changes in the temporal resolution of the observation. We used a high-speed camera to record movement sequences of 20 Acanthodactylus boskianus lizards. Then, we gradually decreased the resolution of the data and calculated the foraging indices at different temporal resolutions. When considering the range of temporal resolutions that are relevant for field observations with unassisted vision, we found 68% and 48% difference in MPM and PTM estimates, respectively. When using the highest resolution, our estimate of MPM was an order of magnitude higher than all prior reported values for lizards. Our results raise major concerns regarding the use of already published movement-based indices, and enable us to recommend how new foraging data should be collected.

scholarly journals Sedimentation process of ashfall during a Vulcanian eruption as revealed by high-temporal-resolution grain size analysis and high-speed camera imaging

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
T. Miwa ◽  
Y. Iriyama ◽  
M. Nagai ◽  
F. Nanayama
Keyword(s):  
Grain Size ◽  
High Speed ◽  
Volume Fraction ◽  
High Temporal Resolution ◽  
High Speed Camera ◽  
Vulcanian Eruption ◽  
Camera Imaging ◽  
Sedimentation Process ◽  
Constant Height ◽  
Ash Aggregates

AbstractWe here examined the sedimentation process of falling ash particles during a short-lived Vulcanian eruption at Sakurajima volcano, Japan, using high-speed camera imaging of airborne ash particles, as well as grain size analyses of ash samples collected at high temporal resolution. Ashfalls from a sequence of two Vulcanian eruptions at 10:44 and 11:26 JST (Japan Standard Time) on 26 March 2016 were investigated. The field site for imaging and sampling was located approximately 3.5 km from the vent. The ash particles collected exhibit bimodal grain size distributions (GSDs). The median particle size of the main subpopulation decreased throughout the ashfall owing to size-dependent segregation of ash particles from a single source released from a constant height. The volume fraction of the subordinate subpopulation is interpreted to represent a component of ash aggregates and shows an increase in its volume fraction after the eruption onset. High-speed camera imaging reveals that the mean particle density decreased over time as the ashfall continued. These data suggest an increasing contribution of low-density aggregates during the course of the ashfall. The temporal changes in the density of airborne ash particles and in the GSD of ash samples demonstrate that the sedimentation process during a Vulcanian eruption at Sakurajima volcano is characterized by sedimentation of ash particles from transient eruption plumes at constant height, in which ash aggregation increases over time. Moreover, time series analysis of the ash falling rate shows that secondary thickening occurred during these Vulcanian eruptions and that this can be triggered by the settling of ash aggregates.

scholarly journals Extended Joint Sparsity Reconstruction for Spatial and Temporal ERT Imaging

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 4014 ◽  
Author(s):  
Bo Chen ◽  
Juan Abascal ◽  
Manuchehr Soleimani
Keyword(s):  
Temporal Resolution ◽  
High Speed ◽  
Low Cost ◽  
Control Process ◽  
Industrial Applications ◽  
High Temporal Resolution ◽  
Conductivity Distribution ◽  
Dynamic Movement ◽  
Wide Range ◽  
The Time Domain

Electrical resistance tomography (ERT) is an imaging technique to recover the conductivity distribution with boundary measurements via attached electrodes. There are a wide range of applications using ERT for image reconstruction or parameter calculation due to high speed data collection, low cost, and the advantages of being non-invasive and portable. Although ERT is considered a high temporal resolution method, a temporally regularized method can greatly enhance such a temporal resolution compared to frame-by-frame reconstruction. In some of the cases, especially in the industrial applications, dynamic movement of an object is critical. In practice, it is desirable for monitoring and controlling the dynamic process. ERT can determine the spatial conductivity distribution based on previous work, and ERT potentially shows good performance in exploiting temporal information as well. Many ERT algorithms reconstruct images frame by frame, which is not optimal and would assume that the target is static during collection of each data frame, which is inconsistent with the real case. Although spatiotemporal-based algorithms can account for the temporal effect of dynamic movement and can generate better results, there is not that much work aimed at analyzing the performance in the time domain. In this paper, we discuss the performance of a novel spatiotemporal total variation (STTV) algorithm in both the spatial and temporal domain, and Temporal One-Step Tikhonov-based algorithms were also employed for comparison. The experimental results show that the STTV has a faster response time for temporal variation of the moving object. This robust time response can contribute to a much better control process which is the main aim of the new generation of process tomography systems.

scholarly journals Polarity symmetry of leaders in moist air

2021 ◽  
Author(s):  
Shengxin Huang ◽  
Weijiang Chen ◽  
Zhong Fu ◽  
Weidong Shi ◽  
Nianwen Xiang ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
High Speed ◽  
High Speed Camera ◽  
Moist Air ◽  
Macroscopic Behavior ◽  
Outstanding Problem ◽  
The Difference ◽  
Insight Into ◽  
Bidirectional Development

Abstract The most important physics underlying lightning is the leader discharge. The presence or absence of space stems/leaders in leader steps is the key to the polarity asymmetry of leaders, which describes the difference in macroscopic behavior between positive and negative leaders and is a long-term consensus among lightning physicists. It is generally believed that negative leader steps are led by space stem, and there is no space stem/leader in positive leader discharges. Here we report the emergence of the space stem and the bidirectional development of the space leader in positive leader steps in moist air, using a high-speed camera with unprecedented spatial-temporal resolution. The lifetime of space stem/leader in positive leader steps is shorter than that in negative leader steps, causing the uncover of space stem/leader in previous studies. The bidirectional development of space leaders in positive leader steps may be an important source for VHF radiations, illuminating insight into the outstanding problem that how positive lightning leaders produce VHF radiation.

Slamming Impacts of Hydrodynamically–Supported Craft

2014 ◽  
Author(s):  
Christine M. Ikeda ◽  
Carolyn Q. Judge
Keyword(s):  
Temporal Resolution ◽  
Structural Damage ◽  
High Speed ◽  
Irregular Waves ◽  
Scale Model ◽  
High Temporal Resolution ◽  
Pressure Measurements ◽  
Calm Water ◽  
Point Pressure ◽  
Wave Slamming

High–speed planing boats are subject to repeated slamming impacts, which can cause structural damage and discomfort or injury to passengers. The goal of this research is to study the fundamental physics of the water-impact of high–speed planing hulls and to measure the slamming loads and resulting motions of the craft upon re–entry into the water after becoming partially airborne. A set of towed scale–model experiments was conducted in calm water, regular waves and irregular waves to capture a sequence of individual impact events. Pressure measurements were taken on the bottom of the hull using both point sensors (PCB Piezotronics) and a pressure mapping system (Tekscan). The pressure signals from the pressure pads (providing both spatial and temporal resolution) and the point–pressure measurements (high temporal resolution) will be presented for individual slam events, allowing a deterministic approach to investigating high–speed planing craft wave slamming.

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