Instantaneous Visualization Research Articles

Real-time CBCT imaging and motion tracking via a single arbitrarily-angled x-ray projection by a joint dynamic reconstruction and motion estimation (DREME) framework

Objective.Real-time cone-beam computed tomography (CBCT) provides instantaneous visualization of patient anatomy for image guidance, motion tracking, and online treatment adaptation in radiotherapy. While many real-time imaging and motion tracking methods leveraged patient-specific prior information to alleviate under-sampling challenges and meet the temporal constraint (<500 ms), the prior information can be outdated and introduce biases, thus compromising the imaging and motion tracking accuracy. To address this challenge, we developed a frameworkdynamicreconstruction andmotionestimation (DREME) for real-time CBCT imaging and motion estimation, without relying on patient-specific prior knowledge.Approach.DREME incorporates a deep learning-based real-time CBCT imaging and motion estimation method into a dynamic CBCT reconstruction framework. The reconstruction framework reconstructs a dynamic sequence of CBCTs in a data-driven manner from a standard pre-treatment scan, without requiring patient-specific prior knowledge. Meanwhile, a convolutional neural network-based motion encoder is jointly trained during the reconstruction to learn motion-related features relevant for real-time motion estimation, based on a single arbitrarily-angled x-ray projection. DREME was tested on digital phantom simulations and real patient studies.Main Results.DREME accurately solved 3D respiration-induced anatomical motion in real time (∼1.5 ms inference time for each x-ray projection). For the digital phantom studies, it achieved an average lung tumor center-of-mass localization error of 1.2 ± 0.9 mm (Mean ± SD). For the patient studies, it achieved a real-time tumor localization accuracy of 1.6 ± 1.6 mm in the projection domain.Significance.DREME achieves CBCT and volumetric motion estimation in real time from a single x-ray projection at arbitrary angles, paving the way for future clinical applications in intra-fractional motion management. In addition, it can be used for dose tracking and treatment assessment, when combined with real-time dose calculation.

An affordable, field-deployable detecting system for cyanide ion – Investigating applications in real time uses

A highly efficient system that incorporates the instantaneous visualization of the cyanide ion in water was synthesized by keeping the fluorophore system (electron donor) as a julolidine-coumarin conjugate and changing the electron acceptor unit. The probes exhibit a notable color change in normal and UV light. The probe interaction modalities are based on the ICT process. With a detection limit in the nM range, it may preferentially react with cyanide, which is less than the tolerable level of 1.9 μM. According to 1H NMR data, the probes detect cyanide ions by nucleophilic addition reaction mechanism. Furthermore, current probe successfully determines real resources, including cyanide containing cassava powder, sprouted potatoes and various water samples. Besides the test strips, an electronic Arduino device was also employed to detect the cyanide ion. As such, the developed probes exhibit outstanding practical application with respect to the cyanide ion.

Smart Industrial Internet of Things Framework for Composites Manufacturing.

Composite materials are increasingly important in making high-performance products. However, contemporary composites manufacturing processes still encounter significant challenges that range from inherent material stochasticity to manufacturing process variabilities. This paper proposes a novel smart Industrial Internet of Things framework, which is also referred to as an Artificial Intelligence of Things (AIoT) framework for composites manufacturing. This framework improves production performance through real-time process monitoring and AI-based forecasting. It comprises three main components: (i) an array of temperature, heat flux, dielectric, and flow sensors for data acquisition from production machines and products being made, (ii) an IoT-based platform for instantaneous sensor data integration and visualisation, and (iii) an AI-based model for production process forecasting. Via these components, the framework performs real-time production process monitoring, visualisation, and prediction of future process states. This paper also presents a proof-of-concept implementation of the framework and a real-world composites manufacturing case study that showcases its benefits.

Vortical structures and passive scalar transport in starting process of annular purging jet

The evolution of vortical structures and passive scalar transport in the starting process of annular purging jets are numerically investigated by large eddy simulation. Three flow configurations with different nozzle-to-plate distances at a fixed radius ratio of 0.71 and the Reynolds number of 13 750 are simulated. The numerical results are validated against documented experimental data. Three stages during the evolution are proposed based on instantaneous flow visualizations and assessed by calculating the circulation changes of the annular jets and vortex rings. The vortical structures are identified to understand the three-dimensional characteristics. The entrainment process is analyzed focusing on the passive scalar transport in the flow fields and is correlated with the cleaning performance of annular purging jets. The flow structures dominate the process of scalar mixing, especially the inner and outer vortex rings. The large-scale motions of trailing jets cause the intermittent events of scalar transport. During the starting process, the cleaning performance is better with a smaller nozzle-to-plate distance, while the cleaning efficiency may reach the optimum at a moderate distance. The cleaning process is limited by the scalar diffusion and entrainment process. These findings highlight the significance of flow structures for effective cleanness of temperature and contaminations in the purging systems.

Visualizing simultaneous eye-hand movements in a MATLAB dashboard

Eye-hand coordination (EHC) is crucial to our daily activities, and its underlying mechanisms are being intensely studied. The analysis of simultaneous eye and hand movements can provide valuable insights into EHC, particularly for individuals struggling with dexterous control, such as might be caused by stroke or traumatic brain injuries. Despite advancements in motion-capture and eye tracking technologies, there is currently no automated method for visualizing concurrent eye- and hand-movement data. To address this need, we have developed a MATLAB-based dashboard designed for near instantaneous analysis and visualization of eye and hand-tracking data. This paper introduces the design of the dashboard and presents experimental results obtained from its application, leveraging simulated data inspired by our recent work in stroke. This testing suggests that our solution has the potential to significantly aid in understanding and investigating EHC by providing side-by-side and time-locked comparison of eye/hand movements along with their timing and spatio-temporal errors, offering novel opportunities for research and clinical applications.•Continuous eye movement data is collected throughout the experiment•Continuous hand movement data is collected throughout the experiment•Combine datasets and display time-locked eye-hand data in a single dashboard

Sub-filter-scale shear stress analysis in hypersonic turbulent Couette flow

Direct numerical simulations of hypersonic turbulent Couette flows are performed for top-wall Mach numbers of 6, 7 and 8, inspired by non-reactive high-enthalpy wind tunnel free-stream conditions, with the goal of analysing the physical processes driving the sub-filter-scale (SFS) stresses to inform development of large-eddy simulation techniques for hypersonic wall-bounded flows. Semi-local scaling laws collapse mean profiles and second-order turbulent statistics well, in spite of the strong wall-normal gradients of temperature and density. On the other hand, the SFS shear stresses exhibit an unexpected profile characterized by a region of pronounced shear stress deficit, which becomes more pronounced for higher Mach numbers. Instantaneous visualizations suggest that the SFS shear stress deficit is induced by the counter-gradient resolved momentum transport driven by residual velocity motions at the interface between high-density low-speed streaks being ejected away from the wall, and low-density high-speed ones replacing the displaced fluid, qualifying this as a compressibility effect. It is shown that the SFS shear stresses are primarily driven by second-order interactions between residual velocities, in spite of their triply nonlinear nature. This, in turn, motivated a statistical quadrant analysis revealing the presence of a SFS shear stress deficit, that is, SFS processes driving momentum transport of the resolved field towards the top wall. Additionally, higher-Reynolds-number simulations reveal that there is an upper limit of spatial filter widths to resolve large-scale structures, and such deficit is observable at any Reynolds number when a reasonable spatial filter is applied.

A Numerical Test Rig for Turbomachinery Flows Based on Large Eddy Simulations With a High-Order Discontinuous Galerkin Scheme—Part III: Secondary Flow Effects

Abstract In this final paper of a three-part series, we apply the numerical test rig based on a high-order discontinuous Galerkin scheme to the MTU T161 low-pressure turbine with diverging end walls at off-design Reynolds number of 90,000, Mach number of 0.6, and inflow angle of 41 deg. The inflow end wall boundary layers are prescribed in accordance with the experiment. Validation of the setup is shown against recent numerical references and the corresponding experimental data. Additionally, we propose and conduct a purely numerical experiment with upstream bar wake generators at a Strouhal number of 1.25, which is well above what was possible in the experiment. We discuss the flow physics at midspan and in the end wall region and highlight the influence of the wakes from the upstream row on the complex secondary flow system using instantaneous flow visualization, phase averages, and modal decomposition techniques.

Seamless real-time thermal imaging system with ESP8266: wireless data transfer and display using UDP

Thermal imaging technology has become increasingly popular for various applications, including industrial monitoring, building automation, and medical diagnostics. However, existing thermal imaging systems often come with high costs and limited connectivity options. In this paper, we propose a method to address these challenges by utilizing the ESP8266 microcontroller to create a thermal imaging system that can measure thermal pixel values, transfer the data wirelessly using the ESP8266’s networking capabilities and display the pixel data in real-time on a Thin-film-transistor liquid-crystal (TFT) display. The objective is to establish a seamless and real-time transfer of thermal images within a local network environment. User datagram protocol (UDP) supports transmission via broadcast and multicast, making it highly efficient for delivering data to multiple clients or devices on a network. It allows a single UDP packet to be simultaneously sent to multiple destinations, enhancing its effectiveness. This feature simplifies the implementation of network protocols and applications, reducing their overall complexity. UDP is particularly well-suited for devices with limited resources, such as microcontrollers or embedded systems, where memory and computing power are constrained. Experimental results demonstrate the successful transmission and display of thermal pixel data between the ESP8266 microcontrollers using the UDP protocol. The project utilizes the Arduino framework along with ESP8266WiFi and UDP libraries to enable network connectivity and UDP communication. The sender and receiver devices are connected to the same local network, guaranteeing efficient and low-latency transmission of thermal pixel data. The system achieves real-time communication within a radius of approximately 15–18 m, ensuring immediate visualization of thermal images on connected displays. By minimizing latency, the system enables a seamless and instantaneous viewing experience offering seamless and instantaneous image visualization for the users.

Navier–Stokes simulations of vertical sloshing with time-periodic excitation

An in-house Navier–Stokes multiphase VOF (Volume-Of-Fluid) solver is used to study sloshing phenomena in a partially filled rectangular tank subjected to vertical sinusoidal excitation, with the main goal of characterizing the effects of vertical acceleration and excitation frequency on the flow dynamics. The solver is validated through comparison with analytical solutions and with available experiments of vertical sloshing. We find that the computed forces acting on the tank walls are well predicted, both in two- and three-dimensional numerical simulations. The flow dynamics is found to be significantly affected by the forcing parameters, and to exhibit more chaotic and three-dimensional nature in cases with strong acceleration and low forcing frequency. As a consequence, certain properties as the energy dissipation and the mixing efficiency of the system are poorly predicted from two-dimensional simulations in that range of parameters, making more expensive three-dimensional simulations necessary. The time history of the sloshing force and instantaneous flow visualizations are used to analyze the effects of liquid impacting on the walls on energy exchanges between the fluid and the tank. Finally, the evolution of mixing efficiency and its influence on the energy losses are discussed.

Large-eddy simulation of turbulent channel flows with antifouling-featured bionic microstructures

The large-eddy simulation of a shark skin surface at Reynolds numbers of Reτ=1200, 2400, and 4500 is carried out in a fully turbulent flow channel to investigate the antifouling mechanism of shark skin from the perspective of hydrodynamics. The antifouling properties are validated through the confocal laser scanning microscopy of microorganism settlement and a measurement of the reduction in pollutant mass. A large-eddy simulation database is then analyzed, focusing on mean and turbulent statistics, to explain the flow characteristics of time-varying fields of the flow that surrounds and skims over the shark skin. A phenomenological scenario based on instantaneous visualizations of vortical events using the Q-criterion is put forward to identify the spatiotemporal evolution of turbulent coherent structures in the outer region. Subsequently, the proposed scenario is accessed by analyzing two-point correlation coefficients, the conditional averaging of vortical events, the wall friction coefficient distribution, and the spatiotemporal evolution of vortices. The flow patterns are predominantly driven by the periodic emission of hairpin-type vortices, which form a strong shear layer and exacerbate shear stress and momentum exchange. Furthermore, these vortices are associated with the generation of a bicyclical system involving an unsteady propagation of turbulent fluids, which develops separately near the front and back of each shark scale. These modes elaborate the antifouling mechanism of shark skin. Analysis of the probability density function and the spatiotemporal map reveals that these strong events have high levels of intermittency in time and space, which vitally contributes to the antifouling properties manifested in the evolution of periodic shear friction over different surfaces.

Evolutions of hydrodynamic and electromagnetic wakes induced by underwater vehicles

The electromagnetic wake induced by the movement of stratified conductive seawater in the presence of the geomagnetic ambiance contains vital information for non-acoustic detection. However, the intricate mechanism among hydrodynamics, ions transports, and vortex evolution has not been systematically explored, which synergistically generate the electromagnetic wake. In this context, an interdisciplinary model involving continuity, momentum, heat and mass transfer, and Maxwell's equations is constructed by the ANSYS Fluent software to address the evolution of wake characteristics behind a full-scale submarine-propeller vehicle. The instantaneous visualizations including velocity distributions, vortex interactions, electromagnetic signatures, and vortex dynamics during downstream evolution are reproduced by the high-fidelity numerical simulations. Tip vortex pairing in the circumferential direction and secondary vortex system originating from the local distortions in the helical morphology due to the wake of the sails are observed and described. Flow fields and electromagnetic features at different axial and radial positions in the wake are also discussed. The results manifest that the pronounced intensity of the induced magnetic field can attain 0.5 nT, which can be detected by precise magnetometers. Moreover, velocity components and induced magnetic fields are thoroughly examined to reveal the mechanism of induced electromagnetic field generation, which is closely linked to the flow velocity and background geomagnetic field. Subsequently, dynamic analyses by power spectral densities are executed to further inspect the frequency characteristics. These scientific findings provide beneficial insights for the research on hydrodynamic and electromagnetic wake, especially considering the potential application of submersible non-acoustic detection.

Turbulent flow around a short rectangular cylinder in uniform flow at moderate Reynolds numbers

The influence of Reynolds number (Re) on the wake characteristics, Kelvin-Helmholtz instabilities and von-Kármán vortex shedding process around a short rectangular cylinder with length to height ratio of 0.5 was studied using particle image velocimetry. The Reynolds numbers based on cylinder height and free-stream velocity ranged from 3000 to 21000. The flow characteristics were analyzed using the instantaneous and mean velocity fields, as well as the Reynolds stresses, while the unsteady dynamics were elucidated using frequency spectra, proper orthogonal decomposition (POD) and reverse flow area. The results demonstrate that the size of the wake vortex reduced but the magnitudes of the Reynolds stresses increased with increasing Re, until Reynolds number independence is reached at Re = 10000. Regardless of Reynolds number, spectral analyses of the velocity fluctuations, POD mode coefficients and fluctuating reverse flow area showed dominant peaks at the same fundamental vortex shedding frequency. Meanwhile, instantaneous flow visualization showed that the structural coherency of the large-scale vortices increased with increasing Reynolds number. Cross-correlation analysis also revealed that the odd and even POD mode coefficients of the first two mode pairs, respectively, acted to contract and expand the instantaneous reverse flow area at the higher Reynolds numbers.

Large-eddy simulation of separated turbulent flows over a three-dimensional hill using WRF and OpenFOAM

It is not clearly known about the limitations of the large-eddy simulation (LES) mode of an atmospheric model (WRF) in predicting the microscale flows for engineering purpose. This study chooses a typical separated turbulent flow past a three-dimensional axisymmetric hill and investigates the performance of WRF-LES in comparison with the popular CFD solver (OpenFOAM). The numerical models and conditions are set similarly between the two codes. The instantaneous visualization shows that both WRF-LES and OpenFOAM-LES can produce the primary flow features, including hairpin vortices, horseshoes, and surface-shear-induced vortices at different scales, with high similarity. Nevertheless, the turbulent kinetic energy in the near wake produced by WRF-LES is underestimated, in comparison with WRF-LES. The energy spectra suggest that WRF-LES using the high-order advection schemes has a stronger capacity of generating and maintaining small-scale turbulent motions than OpenFOAM-LES. Furthermore, the deviation of numerical dissipation behavior is examined between the two solvers.

Measuring material thickness changes through tri-aperture digital speckle pattern interferometry

A configuration for the measurement of thickness changes in materials through one-shot digital speckle pattern interferometry (DSPI) was developed. The phase maps calculation was made by adding carrier fringes by the multiple aperture principle and Fourier Transform Method (FTM). With this setup, interferometry configurations verified that the simultaneous and instantaneous visualization of two opposite faces of a surface is possible. In addition, the combination of the simultaneous results obtained from both sides of the material makes it possible to determine displacements with greater sensitivity or to identify changes in their thickness. The validation and demonstrative tests were carried out with a 1-mm-thick aluminum plate with a 5-mm diameter through hole coated. Thickness changes to 2 μm were measured.

Comparative numerical investigation of wake effect on low-pressure turbine endwall flow

In low-pressure turbine linear cascade experiments, the upstream stator vanes are often modeled by moving bar wake generators. Different from the majority of the earlier wake effect research which is concerned with less aggressively loaded airfoils, here front-loaded high-lift airfoils are considered for both stator and rotor. Implicit large-eddy simulations of the flow through a 50% reaction stage with stator vanes and rotor blades as well as a linear cascade with bar wake generators and rotor blades were carried out and the wake effect on the flow through the rotor was investigated. The chord-based Reynolds number for the simulations was 100,000. For the chosen front-loaded high-lift airfoil the stator wake is dominated by pronounced endwall structures which are lacking for the bar wake generator. Instantaneous flow visualizations reveal a periodic suppression of the two-dimensional rotor blade suction-side separation for both configurations. With upstream stator vanes, the wake endwall structures appear to be chiefly responsible for the suppression of the rotor blade passage vortex and corner separation. For the bar wake generator, the wakes are wider and the wake effect is spread out over a larger portion of the wake passing period. The passage vortex and corner separation remain mostly intact.

Experimental Investigation of Ground Effect on the Vortical Flow Structure of a 40° Swept Delta Wing

The ground effect influences the flow structure on a delta wing during landing and take-off processes. In this regard, comprehensive instantaneous velocity measurements and flow visualizations were carried out by particle image velocimetry and dye flow visualization techniques to reveal the ground effect on leading-edge vortex characteristics of a 40° swept delta wing. The flow behaviors on the delta wing under the impact of the ground were analyzed at two angles of attack, 8° and 11°, and the space between the ground and lower surface of the wing was nondimensionalized with the wing’s chord length. It was found that the presence of the ground caused premature leading-edge vortex breakdown due to the increasing adverse pressure gradient on the wing’s suction side along the chord direction. The ground effect caused an increase in peak value and distributions of turbulent kinetic energy on the wing surface that depended on the earlier leading-edge vortex bursting and complex and disorganized flow structures. The value of time-averaged vertical velocity was lower when the delta wing descended from the free-stream flow zone into the ground effect zone because of the blocking of fluid flow in the gap between the ground and pressure surface of the wing. Thus, it can be concluded that the ground effect is very influential on the change of vortical flow characteristics of nonslender delta wings.

Evolutions of the electromagnetic signatures induced by the propagating wake behind a submerged body

The in situ electromagnetic signatures induced by the movement of conductive seawater in the submarine wake subject to the geomagnetic ambience will provide crucial information for non-acoustic detection. However, several complex multi-physical field coupling processes, for instance, ions concentration variations, turbulent vortex structures, and violent heat and mass transfer have not been systematically investigated, which jointly influence the induced electromagnetic signatures in the propagating stratified wake behind a submerged body. To reveal the interaction mechanisms among flow, heat transfer, ions concentration variations, and electromagnetic fields, we construct a novel multidisciplinary model integrating the mass, momentum, energy, ions concentration, and Maxwell's equations. The pronounced range and intensity of the electromagnetic signatures in the near-field wake are obtained by multi-physics field coupling numerical simulations. The instantaneous visualizations of the near-field wake manifest the distinct fluctuations features, revealing that the magnitude of the induced magnetic intensity can be maintained in the order of 10−10 T. 3D spatial evolutions of the electromagnetic variations are further scrutinized by some quantitative profiles, which indicate that the magnitudes of the wake perturbations fall within the current state of the art instrumentation capabilities. Subsequently, further pertinent analyses about the electromagnetic distributions with different navigational velocities are also explored and reported to elucidate the effects of velocity. These scientific findings provide a conducive insight for lucubrating the evolutions of the induced electromagnetic wake, and assist in further promoting the development of the submersible non-acoustic detection.

Electronic Tuning in Reaction‐Based Fluorescent Sensing for Instantaneous and Ultrasensitive Visualization of Ethylenediamine

Manipulation of a multi-physical quantity to steer a molecular photophysical property is of great significance in improving sensing performance. Here, an investigation on how a physical quantity rooted in the molecular structure induces an optical behavior change to facilitate ultrasensitive detection of ethylenediamine (EDA) is performed by varying a set of thiols. The model molecule consisting of a thiol with dual-carboxyl exhibits the strongest fluorescence, which is ascribed to the electron-donating ability and prompted larger orbital overlap and oscillator strength. The elevated fluorescence positively corelated to the increased EDA, endowing an ultrasensitive response to the nanomolar-liquid/ppm-vapor. A gas detector with superior performance fulfills a contactless and real-time management of EDA. We envisage this electron-tuning strategy-enabled fluorescence enhancement can offer in-depth insight in advancing molecule-customized design, further paving the way to widening applications.

Electronic Tuning in Reaction‐Based Fluorescent Sensing for Instantaneous and Ultrasensitive Visualization of Ethylenediamine

AbstractManipulation of a multi‐physical quantity to steer a molecular photophysical property is of great significance in improving sensing performance. Here, an investigation on how a physical quantity rooted in the molecular structure induces an optical behavior change to facilitate ultrasensitive detection of ethylenediamine (EDA) is performed by varying a set of thiols. The model molecule consisting of a thiol with dual‐carboxyl exhibits the strongest fluorescence, which is ascribed to the electron‐donating ability and prompted larger orbital overlap and oscillator strength. The elevated fluorescence positively corelated to the increased EDA, endowing an ultrasensitive response to the nanomolar‐liquid/ppm‐vapor. A gas detector with superior performance fulfills a contactless and real‐time management of EDA. We envisage this electron‐tuning strategy‐enabled fluorescence enhancement can offer in‐depth insight in advancing molecule‐customized design, further paving the way to widening applications.

Investigation of local severe suction on the side walls of a high-rise building by standard, spectral and conditional POD

Local severe suction greatly determines the safe and economic wind-resistant design of cladding system in the façade of buildings. This study focuses on two localized regions with severe suction of a building, i.e., the lower windward corner of side wall and the region immediately upstream of trailing edge. The aspect ratio of building is 3. The characteristics and mechanism of wind peak pressures are investigated by standard, spectral and conditional proper orthogonal decomposition (POD). Spectral POD extracts the space–time modes which oscillate at the single frequency of the anti-symmetric vortex shedding, where the pressure distributions have the shape of ‘dragonfly’ wing and opposite signs on two side walls. Conditional POD is demonstrated to be a powerful tool to study the average evolution of peak pressures. By inspection of conditional POD modes, high positive fluctuating pressure is observed in the trailing portion of the lower side wall, accompanied by the minimum pressure in the windward corner. The identified pressure behaviors provide the statistical evidences for flow reattachment and shear-layer roll-up which were observed by instantaneous flow visualization in the literature. The trailing-edge peak pressure in the middle-height region is induced by trailing-edge vortex of great vorticity concentration. The flow mechanism and occurrence phase of trailing-edge peak pressures are similar to those of infinite-length cylinders.