scholarly journals Stereoscopic PIV measurements using low-cost action cameras

2021 ◽  
Vol 62 (3) ◽  
Author(s):  
Theo Käufer ◽  
Jörg König ◽  
Christian Cierpka
Keyword(s):  
Continuous Wave ◽  
Low Cost ◽  
Frame Rate ◽  
Processing Scheme ◽  
Piv Measurements ◽  
Stereoscopic Piv ◽  
Cost Action ◽  
Image Velocimetry ◽  
Frequency Generator ◽  
Educational Applications

Abstract Recently, large progress was made in the development towards low-cost PIV (Particle Image Velocimetry) for industrial and educational applications. This paper presents the use of two low-cost action cameras for stereoscopic planar PIV. A continuous wave laser or alternatively an LED was used for illumination and pulsed by a frequency generator. A slight detuning of the light pulsation and camera frame rate minimizes systematic errors by the rolling shutter effect and allows for the synchronization of both cameras by postprocessing without the need of hardware synchronization. The setup was successfully qualified on a rotating particle pattern in a planar and stereoscopic configuration as well as on the jet of an aquarium pump. Since action cameras are intended to be used at outdoor activities, they are small, very robust and work autarkic. In conjunction with the synchronization and image pre-processing scheme presented herein, those cameras enable stereoscopic PIV in harsh environments and even on moving experiments. Graphic abstract

Development of a Low Cost Particle Image Velocimetry System for Fluids Engineering Research and Education

2013 ◽  
Author(s):  
Brock P. Ring ◽  
Daniel K. Atkinson ◽  
Andrew W. Henderson ◽  
Evan C. Lemley
Keyword(s):  
Particle Image Velocimetry ◽  
Undergraduate Students ◽  
Particle Image ◽  
Low Cost ◽  
Green Laser ◽  
Frame Rate ◽  
Particle Image Velocimetry System ◽  
Engineering Research ◽  
Image Velocimetry ◽  
The Cost

Particle image velocimetry (PIV) has transformed fluid mechanics research in recent years. PIV also holds the possibility to transform fluids engineering undergraduate education with the ability of students to get hands-on experience in visualization of real flow fields. One barrier to use of PIV is the cost of a system. Research grade systems are often over $100,000 and inaccessible to many undergraduate students. Recent availability of low-cost high-frame-rate digital cameras, lasers, and public domain software offer potential accessibility for PIV for many labs at academic institutions. In this paper we describe the development of a PIV system for under $1000 including specific components and their costs. In our lab this system is currently being used for several liquid flow experiments including obtaining the flow field in and near small bifurcations. Although we are using the system for liquid flows, it may be used for gas flows as well. One issue that is addressed is the cost of flow seeding — this has been solved by using pulverized green algae as seed particles with a strong reflection by a 532 nm green laser. The system is small and portable and is useful for observing flow in locations that are not of direct interest for experiments, but may have a bearing on flow conditions in experimental measurements; such as upstream of test sections. We describe some examples of how we have used the lost-cost PIV system in our lab and how it can be used for fluids engineering education and research. The current research application of this system is performing loss coefficient calculations in a test section using the energy dissipation.

scholarly journals A Local Oscillator Phase Compensation Technique for Ultra-Wideband Stepped-Frequency Continuous Wave Radar Based on a Low-Cost Software-Defined Radio

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 780
Author(s):  
Kazunori Takahashi ◽  
Takashi Miwa
Keyword(s):  
Software Defined Radio ◽  
Initial Phase ◽  
Continuous Wave ◽  
Low Cost ◽  
Local Oscillator ◽  
The Other ◽  
Ultra Wideband ◽  
Single Frequency ◽  
Wave Radar ◽  
Stepped Frequency

The paper discusses a way to configure a stepped-frequency continuous wave (SFCW) radar using a low-cost software-defined radio (SDR). The most of high-end SDRs offer multiple transmitter (TX) and receiver (RX) channels, one of which can be used as the reference channel for compensating the initial phases of TX and RX local oscillator (LO) signals. It is same as how commercial vector network analyzers (VNAs) compensate for the LO initial phase. These SDRs can thus acquire phase-coherent in-phase and quadrature (I/Q) data without additional components and an SFCW radar can be easily configured. On the other hand, low-cost SDRs typically have only one transmitter and receiver. Therefore, the LO initial phase has to be compensated and the phases of the received I/Q signals have to be retrieved, preferably without employing an additional receiver and components to retain the system low-cost and simple. The present paper illustrates that the difference between the phases of TX and RX LO signals varies when the LO frequency is changed because of the timing of the commencement of the mixing. The paper then proposes a technique to compensate for the LO initial phases using the internal RF loopback of the transceiver chip and to reconstruct a pulse, which requires two streaming: one for the device under test (DUT) channel and the other for the internal RF loopback channel. The effect of the LO initial phase and the proposed method for the compensation are demonstrated by experiments at a single frequency and sweeping frequency, respectively. The results show that the proposed method can compensate for the LO initial phases and ultra-wideband (UWB) pulses can be reconstructed correctly from the data sampled by a low-cost SDR.

Development and Testing of an Unmanned Aerial Vehicle for Large Scale Particle Image Velocimetry

2014 ◽  
Author(s):  
Christopher Pagano ◽  
Flavia Tauro ◽  
Salvatore Grimaldi ◽  
Maurizio Porfiri
Keyword(s):  
Particle Image Velocimetry ◽  
Large Scale ◽  
Field Experiments ◽  
Particle Image ◽  
Low Cost ◽  
Surface Flow ◽  
Natural Environments ◽  
Natural Stream ◽  
Image Velocimetry ◽  
Scale Particle

Large scale particle image velocimetry (LSPIV) is a nonintrusive environmental monitoring methodology that allows for continuous characterization of surface flows in natural catchments. Despite its promise, the implementation of LSPIV in natural environments is limited to areas accessible to human operators. In this work, we propose a novel experimental configuration that allows for unsupervised LSPIV over large water bodies. Specifically, we design, develop, and characterize a lightweight, low cost, and stable quadricopter hosting a digital acquisition system. An active gimbal maintains the camera lens orthogonal to the water surface, thus preventing severe image distortions. Field experiments are performed to characterize the vehicle and assess the feasibility of the approach. We demonstrate that the quadricopter can hover above an area of 1×1m2 for 4–5 minutes with a payload of 500g. Further, LSPIV measurements on a natural stream confirm that the methodology can be reliably used for surface flow studies.

Experimental and Numerical Investigations of a Turbulent Flow Behavior in Isolated and Nonisolated Conical Diffusers

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
F. Aloui ◽  
E. Berrich ◽  
D. Pierrat
Keyword(s):  
Turbulent Flow ◽  
Flow Behavior ◽  
Piv Measurements ◽  
Numerical Investigations ◽  
Image Velocimetry ◽  
Sst Model ◽  
Proper Orthogonal ◽  
Hydraulic Circuits

In some industrial processes, and especially in agrofood industries, the cleaning in place mechanism used for hydraulic circuits plays an important role. This process needs a good knowledge of the hydrodynamic flows to determinate the appropriate parameters that assure a good cleaning of these circuits without disassembling them. Generally, different arrangements are present in these hydraulic circuits, such as expansions, diffusers, and elbows. The flow crossing these singularities strongly affects the process of cleaning in place. This work is then a contribution to complete recent studies of “aliments quality security” project to ameliorate the quality of the cleaning in place. It presents experimental and numerical investigations of a confined turbulent flow behavior across a conical diffuser (2α=16 deg). The role of a perturbation caused by the presence of an elbow in the test section, upstream of the progressive enlargement, was studied. The main measurements were the static pressure and the instantaneous velocity fields using the particle image velocimetry (PIV). Post-processing of these PIV measurements were adopted using the Γ2 criterion for the vortices detection and the proper orthogonal decomposition (POD) technique to extract the most energetic modes contained in the turbulent flow and to the turbulent flow filtering. A database has been also constituted and was used to test the validity of the most models of turbulence, and in particular, a variant of the shear stress transport (SST) model.

scholarly journals A Novel Method for Breath Detection via Stepped-Frequency Continuous Wave Ultra-Wideband (SFCW UWB) Radars Based on Operational Bandwidth Segmentation

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3873 ◽  
Author(s):  
Hao Lv ◽  
Teng Jiao ◽  
Yang Zhang ◽  
Fulai Liang ◽  
Fugui Qi ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Doppler Radar ◽  
Ultra Wideband ◽  
Time Dimension ◽  
Processing Scheme ◽  
Practical Applications ◽  
Uwb Radar ◽  
Operational Frequency ◽  
Stepped Frequency ◽  
Breath Detection

Human being detection via ultra-wideband (UWB) radars has shown great prospects in many areas, such as biomedicine, military operation, public security, emergency rescue, and so on. When a person stays stationary, the main feature that separates him/her from surroundings is the movement of chest wall due to breath. There have been many algorithms developed for breath detection while using UWB radars. However, those algorithms were almost based on a basic scheme that focused on processing in the time dimension of UWB data. They did not utilize the benefits from the wide operational bandwidth of UWB radars to show potential superiority over those narrowband systems such as a continuous wave (CW) Doppler radar. In this paper, a breath detection method was proposed based on operational bandwidth segmentation. A basic theoretical model was firstly introduced, indicating that characteristics of breath signals contained in UWB echoes were consistent among the operational frequencies, while those of clutters were not. So, the method divided a set of UWB echo data into a number of subsets, each of which corresponded to a sub-band within the operational bandwidth of the UWB radar. Thus information about the operational frequency is provided for subsequent processing. With the aid of the information, a breath enhancement algorithm was developed mainly by averaging the segmented UWB data along the operational frequency. The algorithm’s performance was verified by data measured by a stepped-frequency CW (SFCW) UWB radar. The experimental results showed that the algorithm performed better than that without the segmentation. They also showed its feasibility for fast detection of breath based on a short duration of data. Moreover, the method’s potential for target identification and impulse-radio (IR) UWB radar was investigated. In summary, the method provides a new processing scheme for UWB radars when they are used for breath detection. With this scheme, the UWB radars have a benefit of greater flexibility in data processing over those narrowband radars, and thus will perform more effectively and efficiently in practical applications.

scholarly journals Gold Nanorods for Light-Based Lung Cancer Theranostics

2018 ◽  
Vol 19 (11) ◽  
pp. 3318 ◽  
Author(s):  
Oscar Knights ◽  
James McLaughlan
Keyword(s):  
Gold Nanorods ◽  
Photothermal Therapy ◽  
Continuous Wave ◽  
Low Cost ◽  
Laser System ◽  
Controlled Synthesis ◽  
Surface Plasmon Resonances ◽  
Plasmon Resonances ◽  
Theranostic Applications ◽  
Cancer Theranostics

Gold nanorods (AuNRs) have the potential to be used in photoacoustic (PA) imaging and plasmonic photothermal therapy (PPTT) due to their unique optical properties, biocompatibility, controlled synthesis, and tuneable surface plasmon resonances (SPRs). Conventionally, continuous-wave (CW) lasers are used in PPTT partly due to their small size and low cost. However, if pulsed-wave (PW) lasers could be used to destroy tissue then combined theranostic applications, such as PA-guided PPTT, would be possible using the same laser system and AuNRs. In this study, we present the effects of AuNR size on PA response, PW-PPTT efficacy, and PA imaging in a tissue-mimicking phantom, as a necessary step in the development of AuNRs towards clinical use. At equivalent NP/mL, the PA signal intensity scaled with AuNR size, indicating that overall mass has an effect on PA response, and reinforcing the importance of efficient tumour targeting. Under PW illumination, all AuNRs showed toxicity at a laser fluence below the maximum permissible exposure to skin, with a maximum of 80% cell-death exhibited by the smallest AuNRs, strengthening the feasibility of PW-PPTT. The theranostic potential of PW lasers combined with AuNRs has been demonstrated for application in the lung.

PIV Measurements Within the Waves of Wavy and Wavy-Annular Horizontal Two-Phase Flow

2005 ◽  
Author(s):  
R. E. Foster ◽  
T. A. Shedd
Keyword(s):  
Particle Image ◽  
Image Processing Algorithm ◽  
Two Phase ◽  
Piv Measurements ◽  
Post Process ◽  
Image Velocimetry ◽  
Processed Form ◽  
Image Pairs ◽  
Particle Images ◽  
The Waves

A novel technique of microscopic Particle Image Velocimetry (PIV) is presented for two-phase annular, wavy-annular and stratified flow. Seeding of opaque particles in a water/dye flow allows the acquisition of instantaneous film velocity data in the film cross-section at the center of the tube in the form of digital image pairs. An image processing algorithm is also described that allows numerical velocities to be distilled from particle images by commercial PIV software. The approach yields promising results for stratified and wavy-annular flows, however highly bubbly flows remain difficult to image and post-process. Initial data images are presented in raw and processed form.

Time-Resolved Particle Image Velocimetry (PIV) Measurements in a Radial Diffuser Pump

2009 ◽  
Author(s):  
Jianjun Feng ◽  
Friedrich-Karl Benra ◽  
Hans Josef Dohmen
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Time Resolved ◽  
Piv Measurements ◽  
Part Load ◽  
Channel Characteristic ◽  
Image Velocimetry ◽  
Pump Stage ◽  
Low Specific Speed ◽  
Load Conditions

The truly time-variant unsteady flow in a low specific speed radial diffuser pump stage has been investigated by time-resolved Particle Image Velocimetry (PIV) measurements. The measurements are conducted at the midspan of the blades for the design condition and also for some severe part-load conditions. The instantaneous flow fields among different impeller channels are analyzed and compared in detail, and more attention has been paid to flow separations at part-load conditions. The analysis of the measured results shows that the flow separations at two adjacent impeller channels are quite different at some part-load conditions. The separations generally exhibit a two-channel characteristic.

scholarly journals Importance of Sub-Grid Scale Modeling for Accurate Aerodynamic Simulations

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Petter Ekman ◽  
James Venning ◽  
Torbjörn Virdung ◽  
Matts Karlsson
Keyword(s):  
The Body ◽  
Small Scale ◽  
Piv Measurements ◽  
Vortical Structures ◽  
Scale Modeling ◽  
Simple Geometry ◽  
Image Velocimetry ◽  
Large Eddy ◽  
Near Wall ◽  
Ahmed Body

Abstract The Ahmed body is one of the most well-investigated vehicle bodies for aerodynamic purposes. Despite its simple geometry, the flow around the body, especially at the rear, is very complex as it is dominated by a large wake with strong interaction between vortical structures. In this study, the flow around the 25 deg Ahmed body has been investigated using large eddy simulations and compared to high-resolution particle image velocimetry (PIV) measurements. Special emphasis was put on studying three commonly used sub-grid scale (SGS) models and their ability to capture vortical structures around the Ahmed body. The ability of the SGS models to capture the near-wall behavior and small-scale dissipation is crucial for capturing the correct flow field. Very good agreement between simulations and PIV measurements were seen when using the dynamic Smagorinsky-Lilly and the wall-adopting local eddy-viscosity SGS models, respectively. However, the standard Smagorinsky-Lilly model was not able to capture the flow patterns when compared to the PIV measurements due to shortcomings in the near-wall modeling in the standard Smagorinsky-Lilly model, resulting in overpredicted separation.

scholarly journals Digital Vein Mapping Using Augmented Reality

2020 ◽  
Vol 13 (6) ◽  
pp. 512-521
Author(s):  
Mohamed Taha ◽  
◽  
Mohamed Ibrahim ◽  
Hala Zayed ◽  
◽  
...  
Keyword(s):  
Augmented Reality ◽  
Real Time ◽  
Infrared Radiation ◽  
Low Cost ◽  
Economic Cost ◽  
Frame Rate ◽  
Infrared Light ◽  
Real Time Processing ◽  
And Gender ◽  
Time Systems

Vein detection is an important issue for the medical field. There are some commercial devices for detecting veins using infrared radiation. However, most of these commercial solutions are cost-prohibitive. Recently, veins detection has attracted much attention from research teams. The main focus is on developing real-time systems with low-cost hardware. Systems developed to reduce costs suffer from low frame rates. This, in turn, makes these systems not suitable for real-world applications. On the other hand, systems that use powerful processors to produce high frame rates suffer from high costs and a lack of mobility. In this paper, a real-time vein mapping prototype using augmented reality is proposed. The proposed prototype provides a compromised solution to produce high frame rates with a low-cost system. It consists of a USB camera attached to an Android smartphone used for real-time detection. Infrared radiation is employed to differentiate the veins using 20 Infrared Light Emitting Diodes (LEDs). The captured frames are processed to enhance vein detection using light computational algorithms to improve real-time processing and increase frame rate. Finally, the enhanced view of veins appears on the smartphone screen. Portability and economic cost are taken into consideration while developing the proposed prototype. The proposed prototype is tested with people of different ages and gender, as well as using mobile devices of different specifications. The results show a high vein detection rate and a high frame rate compared to other existing systems.

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