scholarly journals Depth from Defocus via Active Quasi-random Point Projections

2016 ◽  
Vol 2 (1) ◽  
Author(s):  
Avery Ma ◽  
Francis Li ◽  
Alexander Wong
Keyword(s):  
Measurement Techniques ◽  
Random Projection ◽  
Random Point ◽  
Calibration Model ◽  
Depth Sensing ◽  
Efficient Manner ◽  
Practical Applications ◽  
Depth Measurement ◽  
Depth From Defocus ◽  
Depth Inference

Depth sensing has many practical applications in vision-relatedtasks. While many different depth measurement techniques existand depth camera technologies are constantly being advanced, activedepth sensing still rely on specialized hardware that are highlycomplex and costly. Motivated by this, we present a novel techniquefor inferring depth measurements via depth from defocus usingactive quasi-random point projection patterns. A quasi-randompoint projection pattern is projected onto the scene of interest, andeach projection point in the image captured by a camera is analysedusing a calibration model to estimate the depth at that point.The proposed method has a relatively simple setup, consisting of acamera and a projector, and enables depth inference from a singlecapture. Furthermore, the use of a quasi-random projection patterncan allow us to leverage compressive sensing theory to producefull depth maps in future applications. Experimental resultsshow the proposed system has strong potential for enabling activedepth sensing in a simple, efficient manner.

scholarly journals Randomized Projection Learning Method for Dynamic Mode Decomposition

Mathematics ◽  
2021 ◽  
Vol 9 (21) ◽  
pp. 2803
Author(s):  
Sudam Surasinghe ◽  
Erik Bollt
Keyword(s):  
Dimensional Space ◽  
Low Cost ◽  
Random Projection ◽  
Dynamic Mode Decomposition ◽  
Projection Algorithm ◽  
Dynamic Mode ◽  
Operator Matrix ◽  
Full Spectrum ◽  
Practical Applications ◽  
Mode Decomposition

A data-driven analysis method known as dynamic mode decomposition (DMD) approximates the linear Koopman operator on a projected space. In the spirit of Johnson–Lindenstrauss lemma, we will use a random projection to estimate the DMD modes in a reduced dimensional space. In practical applications, snapshots are in a high-dimensional observable space and the DMD operator matrix is massive. Hence, computing DMD with the full spectrum is expensive, so our main computational goal is to estimate the eigenvalue and eigenvectors of the DMD operator in a projected domain. We generalize the current algorithm to estimate a projected DMD operator. We focus on a powerful and simple random projection algorithm that will reduce the computational and storage costs. While, clearly, a random projection simplifies the algorithmic complexity of a detailed optimal projection, as we will show, the results can generally be excellent, nonetheless, and the quality could be understood through a well-developed theory of random projections. We will demonstrate that modes could be calculated for a low cost by the projected data with sufficient dimension.

scholarly journals Vari-Focal Light Field Camera for Extended Depth of Field

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1453
Author(s):  
Hyun Myung Kim ◽  
Min Seok Kim ◽  
Sehui Chang ◽  
Jiseong Jeong ◽  
Hae-Gon Jeon ◽  
...  
Keyword(s):  
Light Field ◽  
High Reliability ◽  
Focal Length ◽  
Outdoor Environment ◽  
Depth Of Field ◽  
Depth Information ◽  
Single Shot ◽  
Depth Sensing ◽  
Depth Measurement ◽  
Sensing Applications

The light field camera provides a robust way to capture both spatial and angular information within a single shot. One of its important applications is in 3D depth sensing, which can extract depth information from the acquired scene. However, conventional light field cameras suffer from shallow depth of field (DoF). Here, a vari-focal light field camera (VF-LFC) with an extended DoF is newly proposed for mid-range 3D depth sensing applications. As a main lens of the system, a vari-focal lens with four different focal lengths is adopted to extend the DoF up to ~15 m. The focal length of the micro-lens array (MLA) is optimized by considering the DoF both in the image plane and in the object plane for each focal length. By dividing measurement regions with each focal length, depth estimation with high reliability is available within the entire DoF. The proposed VF-LFC is evaluated by the disparity data extracted from images with different distances. Moreover, the depth measurement in an outdoor environment demonstrates that our VF-LFC could be applied in various fields such as delivery robots, autonomous vehicles, and remote sensing drones.

scholarly journals H″IT″ting the Barriers for Exercising during Social Isolation

Biology ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 245 ◽  
Author(s):  
Daniel Souza ◽  
Victor Coswig ◽  
Claudio Andre Barbosa de Lira ◽  
Paulo Gentil
Keyword(s):  
Aerobic Exercise ◽  
Social Isolation ◽  
General Health ◽  
Physical Inactivity ◽  
Mental Health Problems ◽  
Interval Training ◽  
Moderate Intensity ◽  
Low Grade ◽  
Efficient Manner ◽  
Practical Applications

Aerobic exercise is traditionally recommended to improve general health and prevent many non-communicable diseases. However, the measures adopted to control the novel Coronavirus (COVID-19) outbreak culminated with closing of exercise facilities and fitness centers and, as a primary consequence, impaired aerobic exercise practice. This contributed to an increase in risk factors associated with physical inactivity such as insulin resistance, high blood pressure, low-grade inflammation, weight gain, and mental health problems. The scenario is worrisome, and it is important to propose alternatives for exercise practice during the COVID-19 pandemic. Interval training (IT) emerges as an exercise mode that might be feasible, low-cost, and potentially safe to be performed in many different places. IT consists of interspersing relative brief bouts of high-intensity exercise with recovery periods and promotes similar or greater health benefits when compared to moderate-intensity continuous exercise. Among the different types of IT, sprint interval training and “Tabata protocols” might be particularly useful during social isolation. These protocols can be controlled and performed without the need of complex equipment and can be adapted to different places, including domestic environments. In this article, we present variations of IT as possible alternatives to cope physical inactivity during COVID-19 pandemics with a focus on its practical applications. The protocols suggested can be performed without the need of specialized equipment or facilities, in a time-efficient manner, and aiming to prevent detraining or even improve physical fitness and general health.

Depth Measurement Techniques for Silicon Trenches

1987 ◽  
Author(s):  
Tokuo Kure ◽  
Tsutomu Komoda ◽  
Minori Noguchi ◽  
Hideo Sunami ◽  
Tetsuya Hayashida
Keyword(s):  
Measurement Techniques ◽  
Depth Measurement ◽  
Silicon Trenches

Spin–Orbit Torques in Metallic Magnetic Multilayers: Challenges and New Opportunities

SPIN ◽  
2017 ◽  
Vol 07 (03) ◽  
pp. 1740013 ◽  
Author(s):  
Tao Wang ◽  
John Q. Xiao ◽  
Xin Fan
Keyword(s):  
Giant Magnetoresistance ◽  
Rapid Development ◽  
Measurement Techniques ◽  
Random Access ◽  
Magnetic Multilayers ◽  
Spin Transfer Torque ◽  
Spin Torque ◽  
Great Effort ◽  
Spin Orbit ◽  
Practical Applications

Two decades after the discovery of the giant magnetoresistance that revolutionizes the hard disk drive, the rapid development of spin torque-based magnetic random access memory has once again demonstrated the great potential of spintronics in practical applications. While the industrial application is mainly focusing on the implementation of current-induced spin transfer torque (STT) in magnetic tunnel junctions, a new type of spin torque emerges due to the spin–orbit interaction in magnetic multilayers. A great effort has been devoted by the scientific community to study the so-called spin–orbit torque (SOT), which is not only of interest to fundamental science, but also exhibits potential for the application of current-induced magnetization switching. In this paper, we will review recent development in the SOTs including the fundamental understanding, materials development and measurement techniques. We will also discuss the challenges of using the SOT in potential applications, particularly on the switching of perpendicularly magnetized films.

Selective Modification of the Tribological Properties of Aluminum Through Temperature and Dose Control in Oxygen Plasma Source Ion Implantation

2003 ◽  
Vol 18 (12) ◽  
pp. 2779-2792 ◽  
Author(s):  
M. Bolduc ◽  
B. Terreault ◽  
A. Reguer ◽  
E. Shaffer ◽  
R.G. St-Jacques
Keyword(s):  
Low Temperature ◽  
Ion Implantation ◽  
Tribological Properties ◽  
Oxygen Plasma ◽  
Pure Aluminum ◽  
Plasma Source ◽  
Depth Sensing ◽  
Microwave Source ◽  
Depth Measurement ◽  
Plasma Source Ion Implantation

Improvements in the tribological properties of pure aluminum and “aeronautical” alloy AA7075-T651 were obtained by oxygen-ion implantation [(0.7 to 5) × 1017 O/cm2, 30 keV] using our pulsed electron cyclotron resonance plasma source. This oxygen plasma source ion implantation process produced oxide nanoprecipitates that enhanced the hardness up to three times in the surface layer and caused reductions in the scratch depths and the friction coefficients by similar factors. A spectrum of tribological properties was obtained depending on temperature and ion dose. Temperature measurement and control were obtained through an integrated thermocouple and by changing the duty-cycle of the microwave source. The oxygen content and the depth-resolved chemical composition were measured and optimized using x-ray photoelectron spectroscopy (XPS) combined with Ar-ion etching. The tribological properties were investigated by (i) depth-sensing nanoindentation for hardness and Young's modulus, (ii) scratching and scratch-depth measurement via atomic force microscopy (AFM), and (iii) friction force measurements using AFM. Low-temperature (≤160°C) implantations with optimal O-ion doses produced, in both pure and alloyed Al, an approximately 50-nm-thick, smooth, and extremely fine-grained metal–alumina nanocomposite. The resulting surface was hard and stiff but nonbrittle and displayed high scratch resistance and low friction. High-temperature (~430°C) implantation had different effects on pure Al and AA7075. On pure Al, it produced a very hard but brittle Al2O3 layer for which yield points (displacement excursions) were observed at critical load values in the nanoindentation force–displacement curves. On AA7075, XPS chemical profiling revealed an effect of extreme Mg surface segregation and complete Al surface depletion; MgO crystallites formed a rather rough but surprisingly thick layer (>100 nm). The resulting AA7075 surface showed a hardness increase that was substantial but slightly smaller than that obtained at low temperature.

The Chemistry and Physics of Aerogels

2021 ◽  
Author(s):  
Lorenz Ratke ◽  
Pavel Gurikov
Keyword(s):  
Physical Chemistry ◽  
Graduate Students ◽  
Measurement Techniques ◽  
Theoretical Models ◽  
Supercritical Drying ◽  
Environmental Engineering ◽  
Polymer Science ◽  
Practical Applications ◽  
Essential Properties ◽  
Rigorous Treatment

Discover a rigorous treatment of aerogels processing and techniques for characterization with this easy-to-use reference. Presents the basics of aerogel synthesis and gelation to open porous nanostructures, and the processing of wet gels like ambient and supercritical drying leading to aerogels. Describes their essential properties with their measurement techniques and theoretical models used to analyse relations to their nanostructure. Linking the fundamentals and with practical applications, this is a useful toolkit for advanced undergraduates, and graduate students doing research in material and polymer science, physical chemistry, and chemical and environmental engineering.

Granular flow behaviour in the transverse plane of a partially filled rotating cylinder

1997 ◽  
Vol 330 ◽  
pp. 233-249 ◽  
Author(s):  
A. A. BOATENG ◽  
P. V. BARR
Keyword(s):  
Measurement Techniques ◽  
Flow Characteristics ◽  
Rheological Behaviour ◽  
Flow Behaviour ◽  
Rotating Cylinders ◽  
Practical Applications ◽  
Wide Range ◽  
Rotary Kilns ◽  
Particle Velocities ◽  
Bed Material

Material flow in partially filled rotating cylinders (rotary kilns) is encountered in many practical applications of material processing, for example incineration, calcination, grain drying, etc. The flow behaviour in the cross-section is important to other transport mechanisms such as mixing and energy distribution within the bed material. The paper describes an experimental study which was carried out with the objective of understanding and improving our predictive capabilities of the rheological behaviour of granular materials in rotary cylinders. Measurement techniques similar to that used in chute flows have been employed to measure flow characteristics, e.g. particle velocities, granular temperature, and solid concentration (in the shear layer developed between the free surface and the bulk of the bed) for different materials having a wide range of coefficients of restitution. The results of the experiments provide the necessary assumptions, constraints, and data for granular flows in partially filled rotating cylinders.

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