654 research outputs found
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Error Optimization of Machine Vision based Tool Movement using a Hybrid CLONALG and PSO Algorithm
No full textA machine vision system with single monochrome CCD camera and backlight was developed for tool positioning and verification. While evaluating the performance of the developed vision system, the experiments showed that the output of machine vision system was not comparable to the output of sensors embedded in motion stages. Inherent factors like Imaging setup, camera calibration, environmental effects etc. are responsible for the error. These errors must be minimized to achieve maximum efficiency of developed vision system. In this paper, a novel hybrid algorithm is proposed to optimize the tool position error. The proposed algorithm comprises of CLONALG (one of the techniques of Artificial Immune System) and Particle Swarm Optimization (PSO) (a global optimization algorithm). Hybrid algorithm is tested on tool movement ranging from 0.020 mm to 7 mm. Performance of proposed algorithm is evaluated and also compared with CLONALG and PSO algorithms individually
Enhanced performance of an air-assisted electrostatic nozzle: Role of electrode material and its dimensional considerations in spray charging
No full textThe development of reliable means of charging for finely divided particulate matter is among the major portion of the research activities in electrostatic spraying. This paper presents the role of electrode material and engineering aspects in spray charging with emphasis on theoretical considerations of selection of electrode material and its dimensional shape and size. It reveals the charge-to-mass ratio dependency on variables such as electrode material, shape and geometrical specifications, which is in good agreement with the theoretical considerations. For the particular designed electrostatic nozzle, it is found that optimum electrode position is in the range of 2.0–3.0 mm from the nozzle tip. The copper electroplated with nickel as a charging electrode material can be plausible alternative for spray charging as excellent charge-to-mass ratio 2.8 mC/kg is attained for improved efficacy and efficiency of the electrostatic spraying processes. Possible limitations requiring further research includes the design for maximum charge injection rate, which is thought to be limited by corona breakdown, again a trade-off in air media between charging electrode and liquid sheet
Technological improvements in electrostatic spraying and its impact to agriculture during the last decade and future research perspectives – A review
No full textAn important aspect of research in electrostatic force field applications to liquid sprays involves pesticide spraying, painting, printing, thin film coating, medical, Nano biotechnology, transportation etc. The desired attributes of such spraying are uniform deposition onto both directly exposed (adaxial) and obscured (abaxial) crop surfaces which minimizes the off-target losses of active ingredients to soil, water, atmosphere and provides economic pest control. This paper presents an overview of electrostatic spraying technologies in the field of agriculture and perishable fruits/food products emphasizing the key role of advanced electrostatic spraying instrumentation and chronicles the scientific innovations in the parlance of providing cost effective and reliable commercial systems along with an insight on the needs of future research perspectives and directives
Accuracy of 3D cephalometric measurements based on an automatic knowledge-based landmark detection algorithm
No full textPURPOSE:
To evaluate the accuracy of three-dimensional cephalometric measurements obtained through an automatic landmark detection algorithm compared to those obtained through manual identification.
METHODS:
The study demonstrates a comparison of 51 cephalometric measurements (28 linear, 16 angles and 7 ratios) on 30 CBCT (cone beam computed tomography) images. The analysis was performed to compare measurements based on 21 cephalometric landmarks detected automatically and those identified manually by three observers.
RESULTS:
Inter-observer ICC for each landmark was found to be excellent ([Formula: see text]) among three observers. The unpaired t-test revealed that there was no statistically significant difference in the measurements based on automatically detected and manually identified landmarks. The difference between the manual and automatic observation for each measurement was reported as an error. The highest mean error in the linear and angular measurements was found to be 2.63 mm ([Formula: see text] distance) and [Formula: see text] ([Formula: see text]-Me angle), respectively. The highest mean error in the group of distance ratios was 0.03 (for N-Me/N-ANS and [Formula: see text]).
CONCLUSION:
Cephalometric measurements computed from automatic detection of landmarks on 3D CBCT image were as accurate as those computed from manual identification
An augmented image gradients based supervised regression technique for iris center localization
No full textThis paper describes a robust and accurate technique for iris center localization by combining supervised regression based approach and image gradients. The proposed work consist of two stages. The first stage comprises regression approach which is based upon learning of local binary features to detect the periocular regions. In the second stage, image gradients were applied to the extracted eye patch regions to detect the accurate iris centers. The proposed augmented image gradients based supervised regression approach tested on the two publicly available challenging datasets show good accuracy. The results proved that supervised regression technique when augmented with image gradients approach improved the accuracy of iris center detection on the face image acquired under unconstraint conditions. The outcome of the proposed work suggests that by augmenting effective unsupervised techniques such as image gradients improves the accuracy and robustness of the supervised approaches used for face alignment applications. This work may be extended towards the development of accurate and fast eye gaze tracking systems
Controlling Parameters for Plasmonic Photothermal Ablation of a Tumor
No full textThis paper investigates the controllable therapeutic parameters for plasmonic photothermal ablation of a tumor with an objective to specify the parameters (irradiation intensity, irradiation duration, nanoparticle concentration) based on spatial distribution and accumulation of nanoparticles within a tumor. In this study, a melanoma surrounded by healthy tissue is analyzed. Monte Carlo method, Beer's law, and Pennes' bioheat equation are used to compute spatiotemporal thermal ablation zones. Results show that depending on spatial extent of nanoparticle loaded region of a tumor as well as nanoparticle concentration, different ablation zones are attained within tumor. It is shown that a nanoparticle concentration of 0.0001% embedded within 2-3-mm thick tumor periphery, along with irradiation intensity of 1 W/cm2 for duration of 110 s, is required to attain thermal ablation for the considered tumor sizes of 20-40 mm diameter. For lesser extent of nanoparticle loaded region, it is not possible to attain thermal ablation even with higher nanoparticle concentrations. Further it is shown that, for future clinical application of such therapy, through intravenous delivery of nanoparticles, a tumor must possess a certain spatial extent of vascularized region to facilitate the accumulation of nanoparticles in desired concentration for thermal ablation
Tunable unidirectional scattering of ellipsoidal single nanoparticle
No full textWe report unidirectional scattering by tri-axial single ellipsoidal dielectric nanoparticle, which is applicable in the design and development of tunable, low-loss and ultra-compact nanoantennas. Based on the orientation and rotation of the ellipsoidal nanoparticle, three types of modes, one longitudinal mode and two transverse modes, have been excited. Electric and magnetic dipoles have been optically induced in the nanoparticle. Generalized Kerker's conditions have been applied at the interference of optically induced electric and magnetic dipoles. Azimuthally symmetric forward scattering with complete suppression of backward scattering using first Generalized Kerker's condition has been achieved at three different wavelengths for the allowed longitudinal mode and transverse modes in the optical region using single ellipsoidal nanoparticle. Due to 3-fold symmetry, forward scattering can be tuned at different wavelengths, using single ellipsoidal nanoparticle just by changing the direction of the incident electric field
Optical design of off-axis Cassegrain telescope using freeform surface at the secondary mirror
No full textFreeform surfaces enable imaginative optics by providing abundant degrees of freedom for an optical designer as compared to spherical surfaces. An off-axis two-mirror–based telescope design is presented, in which the primary mirror is a concave prolate spheroid and the secondary mirror is freeform surface-based. The off-axis configuration is employed here for removing the central obscuration problem which otherwise limits the central maxima in the point spread function. In this proposed design, an extended X−Y polynomial is used as a surface descriptor for the off-axis segment of the secondary mirror. The coefficients of this extended polynomial are directly related to the Seidel aberrations, and are thus optimized here for a better control of asymmetric optical aberrations at various field points. For this design, the aperture stop is located 500 mm before the primary mirror and the entrance pupil diameter is kept as 80 mm. The effective focal length is 439 mm and covers a full field of view of 2 deg. The image quality obtained here is near diffraction limited which can be inferred from metrics such as the spot diagram and modulation transfer function
Fabrication of ultrathin, free-standing, transparent and conductive graphene/multiwalled carbon nanotube film with superior optoelectronic properties
No full textHere we report a wet chemical technique to obtain transparent electrodes for optoelectronic devices. This technique is simple, facile, low cost and an effective way to prepare ultrathin free standing hybrid graphene/multiwalled carbon nanotubes (MWCNT) films. The graphene/MWCNT films, up to 36 mm in diameter, with controllable thickness and root mean square surface roughness of the order of 12.6 nm are prepared. The ratio of graphene/MWCNT is optimized to make them free standing and easily transferrable on various substrates. The ratio of direct current conductivity to the optical conductivity (σdc/σopt) which is considered as figure of merit for transparent conductors, is enhanced to 10.27 for graphene/MWCNT hybrid films. The prepared films showed outstanding transmittance up to 87.3 ± 1% at 550 nm, 87.9 ± 1% at 800 nm and sheet resistance of 136 ± 22.4 Ω/sq
Extension of D-H parameter method to hybrid manipulators used in robot-assisted surgery.
No full textThe main focus of this work is to extend the applicability of D-H parameter method to develop a kinematic model of a hybrid manipulator. A hybrid manipulator is a combination of open- and closed-loop chains and contains planar and spatial links. It has been found in the literature that D-H parameter method leads to ambiguities, when dealing with closed-loop chains. In this work, it has been observed that the D-H parameter method, when applied to a hybrid manipulator, results in an orientational inconsistency, because of which the method cannot be used to develop the kinematic model. In this article, the concept of dummy frames is proposed to resolve the orientational inconsistency and to develop the kinematic model of a hybrid manipulator. Moreover, the prototype of 7-degree-of-freedom hybrid manipulator, known as a surgeon-side manipulator to assist the surgeon during a medical surgery, is also developed to validate the kinematic model derived in this work