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geometrical calibration

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https://www.readbyqxmd.com/read/30308997/self-calibration-of-an-industrial-robot-using-a-novel-affordable-3d-measuring-device
#1
Martin Gaudreault, Ahmed Joubair, Ilian Bonev
This work shows the feasibility of calibrating an industrial robot arm through an automated procedure using a new, low-cost, wireless measuring device mounted on the robot's flange. The device consists of three digital indicators that are fixed orthogonally to each other on an aluminum support. Each indicator has a measuring accuracy of 3 µm. The measuring instrument uses a kinematic coupling platform which allows for the definition of an accurate and repeatable tool center point (TCP). The idea behind the calibration method is for the robot to bring automatically this TCP to three precisely-known positions (the centers of three precision balls fixed with respect to the robot's base) and with different orientations of the robot's end-effector...
October 10, 2018: Sensors
https://www.readbyqxmd.com/read/30291548/sensor-applications-of-polypyrrole-for-oxynitrogen-analytes-a-dft-study
#2
Fatima Wasim, Naveen Kosar, Tariq Mahmood, Khurshid Ayub
Density functional theory calculations are performed to evaluate the sensing ability of polypyrrole for oxynitrogen analytes. Interaction energies of PPy-X (X = NO2 - , NO2 , and NO) are calculated at B3LYP-CP/6-31G(d) and B3LYP/6-31G(d) levels of theory and compared with the high level calibrated method (M05-2X/aug-cc-pVDZ). B3LYP-CP/6-31G(d) gives the best correlation with the high level calibrated method compared to B3LYP/6-31G(d). Interaction of oligopyrrole with analytes shows a significant effect on the geometric and electronic properties; the conjugation is increased in the pyrrole oligomers and movement of charge is increased over the polymeric backbone...
October 5, 2018: Journal of Molecular Modeling
https://www.readbyqxmd.com/read/30273772/introducing-nano-particle-type-properties-of-ti-n-n-2-6-clusters
#3
Ali H Pakiari, M Salarhaji
In the present research titanium clusters, Tin (n = 2-6), are studied to highlight their tendency to present nano-particle-type properties as their size grows. Electronic and geometrical structures of clusters and cluster-ligands complexes are obtained at the PBE/QZVP level of theory after density functional theory (DFT) calibration. The correlation between chemical reactivity (hardness) and conductivity with nano-particle-type properties are introduced. Interaction energies of these clusters with N2 and C2 H4 ligands are calculated to provide essential information regarding the ascending trend of reactivity as the size of cluster increases...
September 13, 2018: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/30243832/hasan-highly-accurate-sensitivity-for-auto-contrast-corrected-pmri-reconstruction
#4
Md Sakibur Rahman Sajal, Md Kamrul Hasan
A novel method for highly accurate coil sensitivity-map estimation, based on a constrained image-domain multi-channel LMS (c-iMCLMS) algorithm, is proposed for image reconstruction using self-calibrating SENSE. The sensitivity information is extracted by developing an image-domain cross-relation equation using the low-resolution images constructed from the fully sampled central region of the variable density MR data. Then this formulation is solved in an iterative way using a novel sum-of-squares (SOS) constraint...
September 20, 2018: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/30241771/towards-international-standardization-of-immunoassays-for-m%C3%A3-llerian-inhibiting-substance-anti-m%C3%A3-llerian-hormone
#5
Jackie Mc Ferguson, David Pépin, Chinwe Duru, Paul Matejtschuk, Patricia K Donahoe, Chris J Burns
RESEARCH QUESTION: Is formulated and lyophilized, recombinant human Müllerian inhibiting substance, also known as anti-Müllerian hormone (AMH), suitable for the preparation of a WHO international standard to calibrate AMH immunoassays? DESIGN: The AMH content of a trial preparation, coded SS-581, was determined by five laboratories using seven immunoassay methods. Participants were requested to report the content of the preparation in terms of their method calibrators through the measurement of a minimum of five concentrations in the linear part of the dose-response curve...
September 5, 2018: Reproductive Biomedicine Online
https://www.readbyqxmd.com/read/30240722/re-evaluation-of-current-prism-standards-with-recommendations-to-increase-accuracy-in-the-measurement-of-strabismus
#6
Kenn Freedman, Coby Ray, Declan Kirk
PURPOSE: To critically evaluate the traditional standards for holding single prisms in measuring strabismus with the specific goal being to increase the overall accuracy of clinical measurements. DESIGN: Reliability and validity analysis METHODS: Using an analysis involving geometric optics, the effective prism power (EPP), measured in prism diopters (PD) was calculated for glass and acrylic prisms and was the main outcome measure. These results were also validated using optical bench measurements...
September 18, 2018: American Journal of Ophthalmology
https://www.readbyqxmd.com/read/30212543/enabling-tomography-with-low-cost-c-arm-systems
#7
Monica Abella, Claudia de Molina, Nerea Ballesteros, Alba García-Santos, Álvaro Martínez, Inés García, Manuel Desco
In scenarios where the use of a Computed Tomography (CT) is difficult, such as during surgery or in the ICU, the use of a C-arm system to generate tomographic information could contribute with interesting additional clinical information. Recent days are seeing the development of the so-called cone-beam CT (CBCT) based on advanced motorized isocentric C-arm systems. To be able to make use of more basic C-arm systems, apart from the geometric non-idealities common to any CBCT, we need to address other difficulties...
2018: PloS One
https://www.readbyqxmd.com/read/30184166/estimation-and-validation-of-flour-exposure-in-bakeries-in-alberta-canada
#8
Henry Aidoo, Jeremy Beach, Rebecca Elbourne, Jean-Michel F Galarneau, Sebastian Straube, Nicola Cherry
Objectives: In epidemiological studies of work-related ill-health only current exposures can, at best, be measured. Previous exposures may be estimated using contemporaneous hygiene records or published data. This study aimed to create a job exposure matrix for exposure in bakers for use in an ongoing cohort study. Methods: A systematic review was conducted of English language publications on exposures in bakeries. All publications that appeared to contain quantitative measures of exposure to flour dust, wheat allergen, or fungal α-amylase were read independently by two investigators and relevant data extracted...
September 3, 2018: Annals of Work Exposures and Health
https://www.readbyqxmd.com/read/30180274/image-quality-and-dose-characteristics-for-an-o-arm-intraoperative-imaging-system-with-model-based-image-reconstruction
#9
A Uneri, X Zhang, T Yi, J W Stayman, P A Helm, N Theodore, J H Siewerdsen
PURPOSE: To assess the imaging performance and radiation dose characteristics of the O-arm CBCT imaging system (Medtronic Inc., Littleton MA) and demonstrate the potential for improved image quality and reduced dose via model-based image reconstruction (MBIR). METHODS: Two main studies were performed to investigate previously unreported characteristics of the O-arm system. First is an investigation of dose and 3D image quality achieved with filtered back-projection (FBP) - including enhancements in geometric calibration, handling of lateral truncation and detector saturation, and incorporation of an isotropic apodization filter...
September 4, 2018: Medical Physics
https://www.readbyqxmd.com/read/30119582/field-imaging-system-for-hyperspectral-data-3d-structural-data-and-panchromatic-image-data-measurement-based-on-acousto-optic-tunable-filter
#10
Huijie Zhao, Ziye Wang, Guorui Jia, Xudong Li, Ying Zhang
The hyperspectral data and 3D structural data are highly useful in botanical research. But, the two types of information are often acquired separately and hard to be combined. In this work, a novel dual-path configuration based on acousto-optical tunable filter (AOTF) is proposed to acquire an image, structural and hyperspectral information within one acquisition process by a combination of laser triangulation. Under the configuration, the hyperspectral data and the 3D structure can be matched to subpixel level after geometrical calibration...
June 25, 2018: Optics Express
https://www.readbyqxmd.com/read/30119533/low-cost-compact-4-dof-measurement-system-with-active-compensation-of-beam-angular-drift-error
#11
Yubin Huang, Kuang-Chao Fan, Wei Sun, Shujie Liu
In this paper, a compact four-degree-of-freedom (4-DOF) measurement system is presented. With a special optical configuration, the pitch error, yaw error, and two straightness errors of the moving target are able to be detected by only a single laser beam from a collimated laser diode. A 2D hybrid mirror angle steering mount is designed to perform the large angle turning for the axis alignment and very fine angle tuning by PZT actuators for real-time beam drift compensation. A series of calibration and comparison experiments have been carried out to verify the performance of the proposed system...
June 25, 2018: Optics Express
https://www.readbyqxmd.com/read/30117975/precise-and-robust-binocular-camera-calibration-based-on-multiple-constraints
#12
Xia Liu, Zhenyu Liu, Guifang Duan, Jin Cheng, Xuetao Jiang, Jianrong Tan
Precise calibration of a binocular vision system is the foundation of binocular vision measurement. In this paper, we propose a highly precise and robust binocular camera calibration method, which is devoted to minimize the error between the geometric relation of 3D reconstructed feature points and the ground truth, such as adjacent distance error, collinear error, and right-angle error. In addition, the reprojection error and epipolar are introduced to satisfy the homography relation and epipolar geometry theory better...
June 20, 2018: Applied Optics
https://www.readbyqxmd.com/read/30117928/comparison-and-evaluation-of-geometric-calibration-methods-for-infrared-cameras-to-perform-metric-measurements-on-a-plane
#13
R Usamentiaga, C Ibarra-Castanedo, X Maldague
Geometric information from infrared images can complement the information about the measured infrared radiation. However, this requires geometric camera calibration. In this work, three calibration methods for infrared cameras are compared: a direct and an iterative estimation of the transformation between image and world coordinates and a complete camera calibration method using a specifically designed calibration target. The three methods are compared and the obtained performance for metric measurements on a plane is evaluated...
June 20, 2018: Applied Optics
https://www.readbyqxmd.com/read/30115824/numerical-analysis-and-1d-2d-sensitivity-study-for-monolithic-and-laminated-structural-glass-elements-under-thermal-exposure
#14
Marcin Kozłowski, Chiara Bedon, Dániel Honfi
Glass is largely used in architectural and engineering applications (i.e., buildings and vehicles) as a structural material, especially in the form of laminated glass (LG) sections. To achieve adequate and controlled safety levels in these applications, the well-known temperature-dependent behavior of viscoelastic interlayers for LG sections should be properly accounted for during the design process. Furthermore, the materials' thermomechanical degradation with increases of temperature could severely affect the load-bearing performance of glass assemblies...
August 16, 2018: Materials
https://www.readbyqxmd.com/read/30114216/arterial-compliance-probe-for-cuffless-evaluation-of-carotid-pulse-pressure
#15
Jayaraj Joseph, Nabeel P M, Malay Ilesh Shah, Mohanasankar Sivaprakasam
OBJECTIVE: Assessment of local arterial properties has become increasingly important in cardiovascular research as well as in clinical domains. Vascular wall stiffness indices are related to local pulse pressure (ΔP) level, mechanical and geometrical characteristics of the arterial vessel. Non-invasive evaluation of local ΔP from the central arteries (aorta and carotid) is not straightforward in a non-specialist clinical setting. In this work, we present a method and system for real-time and beat-by-beat evaluation of local ΔP from superficial arteries-a non-invasive, cuffless and calibration-free technique...
2018: PloS One
https://www.readbyqxmd.com/read/30114018/depth-of-field-extension-and-objective-space-depth-measurement-based-on-wavefront-imaging
#16
Q Tong, M Chen, Z Xin, D Wei, X Zhang, J Liao, H Wang, C Xie
When all the parts of the wavefront imaging system are kept static after wavefront measuring, the target's images are blurry, because the depth of field (DOF) of the system affects the imaging quality. In this paper, the method for extending the DOF of the wavefront imaging system through an integrated architecture of a liquid-crystal microlens array (LCMLA) powered by electricity and a common photosensitive array, is presented. The DOF can be extended remarkably only by stitching together several sub-images of the LCMLA...
July 9, 2018: Optics Express
https://www.readbyqxmd.com/read/30106674/a-generic-multi-projection-center-model-and-calibration-method-for-light-field-cameras
#17
Qi Zhang, Chunping Zhang, Jinbo Ling, Qing Wang, Jingyi Yu
Light field cameras can capture both spatial and angular information of light rays, enabling 3D reconstruction by a single exposure. The geometry of 3D reconstruction is affected by intrinsic parameters of a light field camera significantly. In the paper, we propose a multi-projection-center (MPC) model with 6 intrinsic parameters to characterize light field cameras based on traditional two-parallel-plane (TPP) representation. The MPC model can generally parameterize light field in different imaging formations, including conventional and focused light field cameras...
August 9, 2018: IEEE Transactions on Pattern Analysis and Machine Intelligence
https://www.readbyqxmd.com/read/30101751/ionization-chamber-dosimetry-based-on-sup-60-sup-co-absorbed-dose-to-water-calibration-for-diagnostic-kilovoltage-x-ray-beams
#18
Fujio Araki, Takeshi Ohno, Suzuna Umeno
The purpose of this study was to develop a new ionization chamber dosimetry formalism for diagnostic kilovoltage x-ray beams based on a 60Co absorbed dose-to-water calibration coefficient . To validate the new chamber dosimetry, 39 fluence spectra of kilovoltage x-rays were calculated, using a SpekCalc program, for Al half-value-layer (Al-HVL) values of 1.4 8.5 mm and tube voltages of 50 137.6 kVp. We used these spectra to calculate the beam quality conversion factor for kilovoltage x-ray beams Qx to a 60Co beam for a PTW 30013 Farmer ionization chamber in a reference geometrical setup (depth = 1 cm in water, field size = 20 × 20 cm2)...
August 13, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/30094777/development-and-internal-validation-of-an-aneurysm-rupture-probability-model-based-on-patient-characteristics-and-aneurysm-location-morphology-and-hemodynamics
#19
Felicitas J Detmer, Bong Jae Chung, Fernando Mut, Martin Slawski, Farid Hamzei-Sichani, Christopher Putman, Carlos Jiménez, Juan R Cebral
PURPOSE: Unruptured cerebral aneurysms pose a dilemma for physicians who need to weigh the risk of a devastating subarachnoid hemorrhage against the risk of surgery or endovascular treatment and their complications when deciding on a treatment strategy. A prediction model could potentially support such treatment decisions. The aim of this study was to develop and internally validate a model for aneurysm rupture based on hemodynamic and geometric parameters, aneurysm location, and patient gender and age...
November 2018: International Journal of Computer Assisted Radiology and Surgery
https://www.readbyqxmd.com/read/30086955/percent-residual-accuracy-for-quantifying-goodness-of-fit-of-linear-calibration-curves
#20
Brian A Logue, Erica Manandhar
Linear models for calibration curves are overwhelmingly created based on minimization of least squares error, with their goodness-of-fit (GOF) quantified using the square of the correlation coefficient (R2 ). Yet, R2 has well-known disadvantages when used to quantify GOF of calibration curves stemming from its calculation based on the absolute error of the signal (i.e., calculated vs. experimental). These disadvantages are exacerbated when using a geometric series of concentrations for calibration standards (e...
November 1, 2018: Talanta
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