Alsmadi, Mutasem Khalil Sari; Noah, Shahrul Azman; Almarashdah, Ibrahim
2009-01-01
We presents in this paper a novel fish classification methodology based on a combination between robust feature selection, image segmentation and geometrical parameter techniques using Artificial Neural Network and Decision Tree. Unlike existing works for fish classification, which propose descriptors and do not analyze their individual impacts in the whole classification task and do not make the combination between the feature selection, image segmentation and geometrical parameter, we propose a general set of features extraction using robust feature selection, image segmentation and geometrical parameter and their correspondent weights that should be used as a priori information by the classifier. In this sense, instead of studying techniques for improving the classifiers structure itself, we consider it as a black box and focus our research in the determination of which input information must bring a robust fish discrimination.The main contribution of this paper is enhancement recognize and classify fishes...
Geometrical geodesy techniques in Goddard earth models
Lerch, F. J.
1974-01-01
The method for combining geometrical data with satellite dynamical and gravimetry data for the solution of geopotential and station location parameters is discussed. Geometrical tracking data (simultaneous events) from the global network of BC-4 stations are currently being processed in a solution that will greatly enhance of geodetic world system of stations. Previously the stations in Goddard earth models have been derived only from dynamical tracking data. A linear regression model is formulated from combining the data, based upon the statistical technique of weighted least squares. Reduced normal equations, independent of satellite and instrumental parameters, are derived for the solution of the geodetic parameters. Exterior standards for the evaluation of the solution and for the scale of the earth's figure are discussed.
Geometric quantization of mechanical systems with time-dependent parameters
Giachetta, G; Sardanashvily, G
2001-01-01
The momentum phase space of a mechanical system with classical parameters is a fiber bundle over a space of parameters. We provide its fiberwise geometric quantization. A Hamiltonian of such a system is affine in the temporal derivative of parameter functions that leads to the geometric Berry phactor phenomena.
A practical guide to geometric regulation for distributed parameter systems
Aulisa, Eugenio
2015-01-01
A Practical Guide to Geometric Regulation for Distributed Parameter Systems provides an introduction to geometric control design methodologies for asymptotic tracking and disturbance rejection of infinite-dimensional systems. The book also introduces several new control algorithms inspired by geometric invariance and asymptotic attraction for a wide range of dynamical control systems. The first part of the book is devoted to regulation of linear systems, beginning with the mathematical setup, general theory, and solution strategy for regulation problems with bounded input and output operators.
Numerical and experimental investigation of geometric parameters in projection welding
DEFF Research Database (Denmark)
Kristensen, Lars; Zhang, Wenqi; Bay, Niels
2000-01-01
Resistance projection welding is widely used for joining of workpieces with almost any geometric combination. This makes standardization of projection welding impossible. In order to facilitate industrial applications of projection welding, systematic investigations are carried out on the geometric...... parameters by numerical modeling and experimental studies. SORPAS, an FEM program for numerical modeling of resistance welding, is developed as a tool to help in the phase of product design and process optimization in both spot and projection welding. A systematic experimental investigation of projection...... welding a disc to a ring with a triangular ring projection has been carried out to study the influence of the geometric parameters in various metal combinations. In these studies, SORPAS has been used as a supporting tool to understand the relationship of the parameters and the phenomena occurring...
Manipulation of the geometric and electronic parameters of metal nanocatalysts
Laskar, Moitree
Metal nanoparticles find wide use in the field of catalysis owing to their high surface to volume ratio. The catalytic activity depends on the interaction between the molecular substrate and catalyst surface. This substrate-catalyst interaction can be regulated by manipulating the geometric and electronic parameters of these nanoparticles. The shape and size of the nanoparticles dictate the geometric parameters whereas their composition controls the electronics of these catalysts. Manipulation of these parameters can be used to tune catalytic activities; hence, a better understanding of their regulation will help in designing efficient catalysts. The synthesis and characterization of a series of monometallic Pd and core shell Au Pd nanoparticles with varying shapes and sizes will be discussed in this presentation. These nanocrystals were used to catalyze two model reactions: selective hydrogenation of 2-hexyne and oxidation of formic acid. Comparison of their catalytic activities by varying one parameter at a time (either size or shape) helps to identify the effect of geometric parameters on catalysis. Additionally, comparison of particles with varying composition but same geometric features provides insight into how the electronics underlying the catalysis can be manipulated through nanostructure architecture. We find that a balance in binding interaction between the substrate and catalyst surface is necessary to design an efficient catalyst and can be achieved with shape-controlled core shell nanocrystals.
Polarization ellipse and Stokes parameters in geometric algebra.
Santos, Adler G; Sugon, Quirino M; McNamara, Daniel J
2012-01-01
In this paper, we use geometric algebra to describe the polarization ellipse and Stokes parameters. We show that a solution to Maxwell's equation is a product of a complex basis vector in Jackson and a linear combination of plane wave functions. We convert both the amplitudes and the wave function arguments from complex scalars to complex vectors. This conversion allows us to separate the electric field vector and the imaginary magnetic field vector, because exponentials of imaginary scalars convert vectors to imaginary vectors and vice versa, while exponentials of imaginary vectors only rotate the vector or imaginary vector they are multiplied to. We convert this expression for polarized light into two other representations: the Cartesian representation and the rotated ellipse representation. We compute the conversion relations among the representation parameters and their corresponding Stokes parameters. And finally, we propose a set of geometric relations between the electric and magnetic fields that satisfy an equation similar to the Poincaré sphere equation.
Interplay between Peptide Bond Geometrical Parameters in Nonglobular Structural Contexts
Directory of Open Access Journals (Sweden)
Luciana Esposito
2013-01-01
Full Text Available Several investigations performed in the last two decades have unveiled that geometrical parameters of protein backbone show a remarkable variability. Although these studies have provided interesting insights into one of the basic aspects of protein structure, they have been conducted on globular and water-soluble proteins. We report here a detailed analysis of backbone geometrical parameters in nonglobular proteins/peptides. We considered membrane proteins and two distinct fibrous systems (amyloid-forming and collagen-like peptides. Present data show that in these systems the local conformation plays a major role in dictating the amplitude of the bond angle N-Cα-C and the propensity of the peptide bond to adopt planar/nonplanar states. Since the trends detected here are in line with the concept of the mutual influence of local geometry and conformation previously established for globular and water-soluble proteins, our analysis demonstrates that the interplay of backbone geometrical parameters is an intrinsic and general property of protein/peptide structures that is preserved also in nonglobular contexts. For amyloid-forming peptides significant distortions of the N-Cα-C bond angle, indicative of sterical hidden strain, may occur in correspondence with side chain interdigitation. The correlation between the dihedral angles Δω/ψ in collagen-like models may have interesting implications for triple helix stability.
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
There are two kinds of methods in researching the crust deformation: geophysical method and geometrical (or observational) method. Considerable differences usually exist between the two kinds of results, because of the datum differences, geophysical model errors, observational model errors, and so on. Thus, it is reasonable to combine the two kinds of information to collect the crust deformation information. To use the reliable geometrical and geophysical information, we have to control the observational and geophysical model error influences on the estimated deformation parameters, and to balance their contributions to the evaluated parameters. A hybrid estimation strategy is proposed here for evaluating the deformation parameters employing an adaptively robust filtering. The effects of measurement outliers on the estimated parameters are controlled by robust equivalent weights. Adaptive factors are introduced to balance the contribution of the geophysical model information and the geometrical measurements to the model parameters. The datum for the local deformation analysis is mainly determined by the highly accurate IGS station velocities. The hybrid estimation strategy is applied in an actual GPS monitoring network. It is shown that the hybrid technique employs locally repeated geometrical displacements to reduce the displacement errors caused by the mis-modeling of geophysical technique, and thus improves the precision of the estimated crust deformation parameters.
Do Lumped-Parameter Models Provide the Correct Geometrical Damping?
DEFF Research Database (Denmark)
Andersen, Lars
This paper concerns the formulation of lumped-parameter models for rigid footings on homogenous or stratified soil. Such models only contain a few degrees of freedom, which makes them ideal for inclusion in aero-elastic codes for wind turbines and other models applied to fast evaluation of struct......This paper concerns the formulation of lumped-parameter models for rigid footings on homogenous or stratified soil. Such models only contain a few degrees of freedom, which makes them ideal for inclusion in aero-elastic codes for wind turbines and other models applied to fast evaluation...... response during excitation and the geometrical damping related to free vibrations of a hexagonal footing. The optimal order of a lumped-parameter model is determined for each degree of freedom, i.e. horizontal and vertical translation as well as torsion and rocking. In particular, the necessity of coupling...... between horizontal sliding and rocking is discussed....
Cosmological parameters from large scale structure - geometric versus shape information
Hamann, Jan; Lesgourgues, Julien; Rampf, Cornelius; Wong, Yvonne Y Y
2010-01-01
The matter power spectrum as derived from large scale structure (LSS) surveys contains two important and distinct pieces of information: an overall smooth shape and the imprint of baryon acoustic oscillations (BAO). We investigate the separate impact of these two types of information on cosmological parameter estimation, and show that for the simplest cosmological models, the broad-band shape information currently contained in the SDSS DR7 halo power spectrum (HPS) is by far superseded by geometric information derived from the baryonic features. An immediate corollary is that contrary to popular beliefs, the upper limit on the neutrino mass m_\
Efficient geometric rectification techniques for spectral analysis algorithm
Chang, C. Y.; Pang, S. S.; Curlander, J. C.
1992-01-01
The spectral analysis algorithm is a viable technique for processing synthetic aperture radar (SAR) data in near real time throughput rates by trading the image resolution. One major challenge of the spectral analysis algorithm is that the output image, often referred to as the range-Doppler image, is represented in the iso-range and iso-Doppler lines, a curved grid format. This phenomenon is known to be the fanshape effect. Therefore, resampling is required to convert the range-Doppler image into a rectangular grid format before the individual images can be overlaid together to form seamless multi-look strip imagery. An efficient algorithm for geometric rectification of the range-Doppler image is presented. The proposed algorithm, realized in two one-dimensional resampling steps, takes into consideration the fanshape phenomenon of the range-Doppler image as well as the high squint angle and updates of the cross-track and along-track Doppler parameters. No ground reference points are required.
MODELING AND COMPENSATION TECHNIQUE FOR THE GEOMETRIC ERRORS OF FIVE-AXIS CNC MACHINE TOOLS
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
One of the important trends in precision machining is the development of real-time error compensation technique.The error compensation for multi-axis CNC machine tools is very difficult and attractive.The modeling for the geometric error of five-axis CNC machine tools based on multi-body systems is proposed.And the key technique of the compensation-identifying geometric error parameters-is developed.The simulation of cutting workpiece to verify the modeling based on the multi-body systems is also considered.
Institute of Scientific and Technical Information of China (English)
Wang Hong-xin; Cheng Shu-kang; Wen Xi-shan; Sun Xiong-fei; Chen Yun-ping
2004-01-01
This paper deals with the experimental study on the correlation between the geometrical parameters of electrical tree and corresponding partial discharge (PD) characteristic parameters in the course of electrical tree aging within cross linked polyethylene (XLPE) insulation. The electrical tree aging tests were performed on specimens removed from a section of 220 kV transmission cable. The PD macroscopic characteristic parameters were found to be significantly dependent on the corresponding geometrical parameters of electrical tree channels in the course of aging of XLPE, and different kind of electrical tree bas different characteristics, and there is obvious correlation between the type of electrical tree and the pre-applied power-frequency stress. Beside, using regression analysis, the expression of the relation between them were obtained,and from which it can be seen that there is significant nonlinear correlation between geometrical parameters of electrical tree and corresponding PD characteristic parameters in the course of aging of XLPE. Therefore, the aging degree of XLPE can be effectively evaluated by recognizing the changing regularity of the PD macroscopic characteristic parameters.
Cosmological parameters from large scale structure - geometric versus shape information
Hamann, Jan; Hannestad, Steen; Lesgourgues, Julien; Rampf, Cornelius; Wong, Yvonne Y. Y.
2010-07-01
The matter power spectrum as derived from large scale structure (LSS) surveys contains two important and distinct pieces of information: an overall smooth shape and the imprint of baryon acoustic oscillations (BAO). We investigate the separate impact of these two types of information on cosmological parameter estimation for current data, and show that for the simplest cosmological models, the broad-band shape information currently contained in the SDSS DR7 halo power spectrum (HPS) is by far superseded by geometric information derived from the baryonic features. An immediate corollary is that contrary to popular beliefs, the upper limit on the neutrino mass mν presently derived from LSS combined with cosmic microwave background (CMB) data does not in fact arise from the possible small-scale power suppression due to neutrino free-streaming, if we limit the model framework to minimal ΛCDM+mν. However, in more complicated models, such as those extended with extra light degrees of freedom and a dark energy equation of state parameter w differing from -1, shape information becomes crucial for the resolution of parameter degeneracies. This conclusion will remain true even when data from the Planck spacecraft are combined with SDSS DR7 data. In the course of our analysis, we update both the BAO likelihood function by including an exact numerical calculation of the time of decoupling, as well as the HPS likelihood, by introducing a new dewiggling procedure that generalises the previous approach to models with an arbitrary sound horizon at decoupling. These changes allow a consistent application of the BAO and HPS data sets to a much wider class of models, including the ones considered in this work. All the cases considered here are compatible with the conservative 95%-bounds ∑mν < 1.16eV, Neff = 4.8±2.0.
Topology Synthesis of Structures Using Parameter Relaxation and Geometric Refinement
Hull, P. V.; Tinker, M. L.
2007-01-01
Typically, structural topology optimization problems undergo relaxation of certain design parameters to allow the existence of intermediate variable optimum topologies. Relaxation permits the use of a variety of gradient-based search techniques and has been shown to guarantee the existence of optimal solutions and eliminate mesh dependencies. This Technical Publication (TP) will demonstrate the application of relaxation to a control point discretization of the design workspace for the structural topology optimization process. The control point parameterization with subdivision has been offered as an alternative to the traditional method of discretized finite element design domain. The principle of relaxation demonstrates the increased utility of the control point parameterization. One of the significant results of the relaxation process offered in this TP is that direct manufacturability of the optimized design will be maintained without the need for designer intervention or translation. In addition, it will be shown that relaxation of certain parameters may extend the range of problems that can be addressed; e.g., in permitting limited out-of-plane motion to be included in a path generation problem.
Miranda, Alexandre F; Sampaio, Francisco J B
2014-06-01
A surgical approach with plaque incision and graft (PIG) to correct Peyronie's disease is the best method for complex, large deviations. However, the geometric and mechanical consequences of this intervention are poorly understood. The aim of this study was to analyze the geometric and mechanical consequences of PIG on penile straighten surgery. A tridimensional penile simile model with a curvature of 85° was created to test all of the most common PIG techniques. PIG with double-Y, H-shape, and Egydio techniques were used to rectify the curved penile model. The results that differed from a rectified cylinder shape were highlighted. All of the analyzed techniques created a geometric distortion that could be linked to poor surgical results. We suggest a new technique to resolve these abnormalities. Current techniques designed to correct penile deviation using PIG present geometric and mechanical imperfections with potential consequences to the postoperative success rate. The new technique proposed in this report could be a possible solution to solve the geometric distortion caused by PIG. © 2014 International Society for Sexual Medicine.
Field investigation on effects of railway track geometric parameters on rail wear
Institute of Scientific and Technical Information of China (English)
SADEGHI J.; AKBARI B.
2006-01-01
Rail wear has dramatic impact on track performance, ride quality and maintenance costs. The amount of rail wear is influenced by various elements among which geometric parameters play an important role. The amount of wear in Iran's railway lines and its imposed maintenance costs oblige us to make modifications on the various geometrical parameters. In order to ensure the effectiveness of these changes, it is necessary to investigate these parameters and their effects on the wear. This research is aimed at studying the effects of different track geometrical parameters on the vertical and lateral wear by conducting a three phase field investigation. The first phase was carried out at the switches of a station, the second phase at a straight line, and the third at a curved line out of the station. The results obtained are analyzed and the role of each track geometrical parameter in the rail wear is discussed. Recommendations for prevention or reduction of rail wear are presented.
Geometric Parameter Identification of a 6-DOF Space Robot Using a Laser-Ranger
Directory of Open Access Journals (Sweden)
Yu Liu
2012-01-01
Full Text Available The geometric parameters of a space robot change with the terrible temperature change in orbit, which will cause the end-effector pose (position and orientation error of a space robot, and so weakens its operability. With this in consideration, a new geometric parameter identification method is presented based on a laser-ranger attached to the end-effector. Then, independence of the geometric parameters is analyzed, and their identification equations are derived. With the derived identification Jacobian matrix, the optimal identification configurations are chosen according to the observability index O3. Subsequently, through simulation the geometric parameter identification of a 6-DOF space robot is implemented for these identification configurations, and the identified parameters are verified in a set of independent reference configurations. The result shows that in spite of distance measurement alone, pose accuracy of the space robot still has a greater improvement, so the identification method is practical and valid.
Numerical Study of Urban Canyon Microclimate Related to Geometrical Parameters
Directory of Open Access Journals (Sweden)
Andrea de Lieto Vollaro
2014-11-01
Full Text Available In this study a microclimate analysis on a particular urban configuration: the—street canyon—has been carried out. The analysis, conducted by performing numerical simulations using the finite volumes commercial code ANSYS-Fluent, shows the flow field in an urban environment, taking into account three different aspect ratios (H/W. This analysis can be helpful in the study on urban microclimate and on the heat exchanges with the buildings. Fluid-dynamic fields on vertical planes within the canyon, have been evaluated. The results show the importance of the geometrical configuration, in relation to the ratio between the height (H of the buildings and the width (W of the road. This is a very important subject from the point of view of “Smart Cities”, considering the urban canyon as a subsystem of a larger one (the city, which is affected by climate changes.
Accurate geometric camera calibration technique using multi-views of a non-metric planar grid
Bingwei, Hui; Gongjian, Wen; Xing, Zhang; Deren, Li
2013-04-01
A robust geometric camera calibration technique with a non-metric planar grid is proposed. For each image of the non-metric grid, a projective model of the grid intersections represented by the grid row and column numbers is derived with sixteen physically meaningful parameters. In this model, intrinsic camera parameters and coefficients of lens distortions are involved. After several images of the same gird have been acquired by the camera awaiting calibrations, two broad steps are taken to work out the camera parameters. Firstly, with two reasonable approximations the projective parameters of all view images are solved linearly and analytically by using the properties of the rotation matrix skillfully. Secondly, with the rigorous projective formulations of non-metric grid intersections, a mathematical optimization model is established to obtain the calibration results with least squares errors. The robustness and accuracy are verified by using many real grabbed images.
Influences of Geometric Parameters upon Nozzle Performances in Scramjets
Institute of Scientific and Technical Information of China (English)
Li Jianping; Song Wenyan; Xing Ying; Luo Feiteng
2008-01-01
This article investigates and presents the influences of geomea'ic parameters of a scramjet exerting upon its nozzle performances. These parameters include divergent angles, total lengths, height ratios, cowl lengths, and cowl angles. The flow field within the scramjet nozzle is simulated numerically by using the CFD software--FLUENT in association with coupled implicit solver and an RNG k-ε tur-bulence model.
STUDY ON NEW METHOD OF IDENTIFYING GEOMETRIC ERROR PARAMETERS FOR NC MACHINE TOOLS
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The methods of identifying geometric error parameters for NC machine tools are introduced. According to analyzing and comparing the different methods, a new method-displacement method with 9 lines is developed based on the theories of the movement errors of multibody system (MBS). A lot of experiments are also made to obtain 21 terms geometric error parameters by using the error identification software based on the new method.
Do Lumped-Parameter Models Provide the Correct Geometrical Damping?
DEFF Research Database (Denmark)
Andersen, Lars
2007-01-01
This paper concerns the formulation of lumped-parameter models for rigid footings on homogenous or stratified soil with focus on the horizontal sliding and rocking. Such models only contain a few degrees of freedom, which makes them ideal for inclusion in aero-elastic codes for wind turbines...
Do Lumped-Parameter Models Provide the Correct Geometrical Damping?
DEFF Research Database (Denmark)
Andersen, Lars
2007-01-01
This paper concerns the formulation of lumped-parameter models for rigid footings on homogenous or stratified soil with focus on the horizontal sliding and rocking. Such models only contain a few degrees of freedom, which makes them ideal for inclusion in aero-elastic codes for wind turbines...
Winter, Samantha Lee; Forrest, Sarah Michelle; Wallace, Joanne; Challis, John H
2017-08-08
The purpose of this study was to validate a new geometric solids model, developed to address the lack of female specific models for body segment inertial parameter estimation. A second aim was to determine the effect of reducing the number of geometric solids used to model the limb segments on model accuracy. The 'full' model comprised 56 geometric solids, the 'reduced' 31, and the 'basic' 16. Predicted whole-body inertial parameters were compared with direct measurements (reaction board, scales), and predicted segmental parameters with those estimated from whole-body DXA scans for 28 females. The percentage root mean square error (%RMSE) for whole-body volume was geometric solids are required to more accurately model the trunk.
Effect of varying geometrical parameters of trapezoidal corrugated-core sandwich structure
Directory of Open Access Journals (Sweden)
Zaid N.Z.M.
2017-01-01
Full Text Available Sandwich structure is an attractive alternative that increasingly used in the transportation and aerospace industry. Corrugated-core with trapezoidal shape allows enhancing the damage resistance to the sandwich structure, but on the other hand, it changes the structural response of the sandwich structure. The aim of this paper is to study the effect of varying geometrical parameters of trapezoidal corrugated-core sandwich structure under compression loading. The corrugated-core specimen was fabricated using press technique, following the shape of trapezoidal shape. Two different materials were used in the study, glass fibre reinforced plastic (GFRP and carbon fibre reinforced plastic (CFRP. The result shows that the mechanical properties of the core in compression loading are sensitive to the variation of a number of unit cells and the core thickness.
DEFF Research Database (Denmark)
Azizaddini, Seyednezamaddin; Lin, Weigang; Dam-Johansen, Kim
2016-01-01
Experiments are performed in a draft tube spouted bed (DTSB) to investigate effects of the operating conditions and the geometric parameters on the hydrodynamics. Geometry parameters, such as heights of the entrained zone, draft tube inner diameter, inner angle of the conical section were studied...
Effect of geometrical parameters on pressure distributions of impulse manufacturing technologies
Brune, Ryan Carl
Impulse manufacturing techniques constitute a growing field of methods that utilize high-intensity pressure events to conduct useful mechanical operations. As interest in applying this technology continues to grow, greater understanding must be achieved with respect to output pressure events in both magnitude and distribution. In order to address this need, a novel pressure measurement has been developed called the Profile Indentation Pressure Evaluation (PIPE) method that systematically analyzes indentation patterns created with impulse events. Correlation with quasi-static test data and use of software-assisted analysis techniques allows for colorized pressure maps to be generated for both electromagnetic and vaporizing foil actuator (VFA) impulse forming events. Development of this technique aided introduction of a design method for electromagnetic path actuator systems, where key geometrical variables are considered using a newly developed analysis method, which is called the Path Actuator Proximal Array (PAPA) pressure model. This model considers key current distribution and proximity effects and interprets generated pressure by considering the adjacent conductor surfaces as proximal arrays of individual conductors. According to PIPE output pressure analysis, the PAPA model provides a reliable prediction of generated pressure for path actuator systems as local geometry is changed. Associated mechanical calculations allow for pressure requirements to be calculated for shearing, flanging, and hemming operations, providing a design process for such cases. Additionally, geometry effect is investigated through a formability enhancement study using VFA metalworking techniques. A conical die assembly is utilized with both VFA high velocity and traditional quasi-static test methods on varied Hasek-type sample geometries to elicit strain states consistent with different locations on a forming limit diagram. Digital image correlation techniques are utilized to measure
Parameter Estimation of Gaussian-Damped Sinusoids from a Geometric Perspective
Pelaia, Thomas
2016-01-01
The five parameter gaussian damped sinusoid equation is a reasonable model for betatron motion with chromatic decoherence of the proton bunch centroid signal in the ring at the Spallation Neutron Source. A geometric method for efficiently fitting this equation to the turn by turn signals to extract the betatron tune and damping constant will be presented. This method separates the parameters into global and local parameters and allows the use of vector arithmetic to eliminate the local parameters from the parameter search space. Furthermore, this method is easily generalized to reduce the parameter search space for a larger class of problems.
Geometrical parameters influence on behavior of the sandwich plates with corrugated core
Directory of Open Access Journals (Sweden)
Djoković Jelena M.
2016-01-01
Full Text Available The influence of geometric parameters on behavior and stiffness of sandwich plates with corrugated core is considered in this paper. The following parameters were analyzed: ratio of core sheet and facing sheet thickness and the ratio of the core’s pitch to the core’s depth, as well as the corrugation angle. It is shown that changes of these parameters can contribute to increase or decrease of the corrugated sandwich plate stiffness.
Kou, Jisheng
2015-07-16
In this paper, we consider an interface model for multicomponent two-phase fluids with geometric mean influence parameters, which is popularly used to model and predict surface tension in practical applications. For this model, there are two major challenges in theoretical analysis and numerical simulation: the first one is that the influence parameter matrix is not positive definite; the second one is the complicated structure of the energy function, which requires us to find out a physically consistent treatment. To overcome these two challenging problems, we reduce the formulation of the energy function by employing a linear transformation and a weighted molar density, and furthermore, we propose a local minimum grand potential energy condition to establish the relation between the weighted molar density and mixture compositions. From this, we prove the existence of the solution under proper conditions and prove the maximum principle of the weighted molar density. For numerical simulation, we propose a modified Newton\\'s method for solving this nonlinear model and analyze its properties; we also analyze a finite element method with a physical-based adaptive mesh-refinement technique. Numerical examples are tested to verify the theoretical results and the efficiency of the proposed methods.
Brachytherapy seed localization using geometric and linear programming techniques.
Singh, Vikas; Mukherjee, Lopamudra; Xu, Jinhui; Hoffmann, Kenneth R; Dinu, Petru M; Podgorsak, Matthew
2007-09-01
We propose an optimization algorithm to solve the brachytherapy seed localization problem in prostate brachytherapy. Our algorithm is based on novel geometric approaches to exploit the special structure of the problem and relies on a number of key observations which help us formulate the optimization problem as a minimization integer program (IP). Our IP model precisely defines the feasibility polyhedron for this problem using a polynomial number of half-spaces; the solution to its corresponding linear program is rounded to yield an integral solution to our task of determining correspondences between seeds in multiple projection images. The algorithm is efficient in theory as well as in practice and performs well on simulation data (approximately 98% accuracy) and real X-ray images (approximately 95% accuracy). We present in detail the underlying ideas and an extensive set of performance evaluations based on our implementation.
Model Study of Wave Overtopping of Marine Structure for a Wide Range of Geometric Parameters
DEFF Research Database (Denmark)
Kofoed, Jens Peter
2000-01-01
The objective of the study described in this paper is to enable estimation of wave overtopping rates for slopes/ramps given by a wide range of geometric parameters when subjected to varying wave conditions. To achieve this a great number of model tests are carried out in a wave tank using irregular...
Geometrical parameter analysis of the high sensitivity fiber optic angular displacement sensor
Sakamoto, João M S; Kitano, Cláudio; Tittmann, Bernhard R
2015-01-01
In this work, we present an analysis of the influence of the geometrical parameters on the sensitivity and linear range of the fiber optic angular displacement sensor, through computational simulations and experiments. The geometrical parameters analyzed were the lens focal length, the gap between fibers, the fibers cladding radii, the emitting fiber critical angle (or, equivalently, the emitting fiber numerical aperture), and the standoff distance (distance between the lens and the reflective surface). Besides, we analyzed the sensor sensitivity regarding any spurious linear displacement. The simulation and experimental results showed that the parameters which play the most important roles are the emitting fiber core radius, the lens focal length, and the light coupling efficiency, while the remaining parameters have little influence on sensor characteristics. This paper was published in Applied Optics and is made available as an electronic reprint with the permission of OSA. The paper can be found at the fo...
On-orbit Geometric Parameters Refinement of Mapping Satellite-1 Triple Line Array Camera
Directory of Open Access Journals (Sweden)
GENG Hongyi
2016-03-01
Full Text Available To find the model and method of on-orbit geometric refinement suitable for the triple line array camera of Mapping Satellite-1, this paper first analyzed the impact of the exterior orientation line element error on the geometric parameters refinement, then eliminated the high-frequency noise by the preprocessing of the attitude data, and compensated the low-frequency flutter of satellite platform in the course of flying by sine function and designed the constant angular error model for the lens of the triple line array camera. In addition, an interior orientation model, using directly pixel coordinates as observations, was constructed based on conventional additional parameter model and the combination of the best refinement model parameters and the solution strategy were determined by the unilateral control extrapolative location. The experiments show that the planar accuracy and vertical accuracy are about 1 GSD and 0.8 GSD by the proposed refinement plan and the rational distribution of GCPS.
Directory of Open Access Journals (Sweden)
Oboetswe Seraga Motsamai
2010-01-01
Full Text Available Effectiveness and efficiency of hydro-cyclone separators are highly dependent on their geometrical parameters and flow characteristics. Performance of the hydro-cyclone can, therefore, be improved by modifying the geometrical parameters or flow characteristics. The mining and chemical industries are faced with problems of separating ore-rich stones from the nonore-rich stones. Due to this problem a certain amount of precious metals is lost to the dumping sites. Plant managers try to solve these problems by stockpiling what could be useless stones, so that they can be reprocessed in the future. Reprocessing is not a sustainable approach, because the reprocessed material would give lower yield as compared to the production costs. Particulate separation in a hydro-cyclone has been investigated in this paper, by using computational fluid dynamics. The paper investigated the influence of various flow and geometric parameters on particulate separation. Optimal parameters for efficient separation have been determined for the density of fluid, diameter of the spigot, and diameter of the vortex finder. The principal contribution of this paper is that key parameters for design optimization of the hydro-cyclone have been investigated.
Directory of Open Access Journals (Sweden)
Aamir Saghir
2015-12-01
Full Text Available The geometric-Poisson exponentially weighted moving average (EWMA chart has been shown to be more effective than the Poisson EWMA chart in monitoring the number of defects in the production processes. In these applications, it is assumed that the process parameters are known or have been accurately estimated. However, in practice, the process parameters are rarely known and must be estimated from reference sample to construct the geometric-Poisson EWMA chart. The performance of the given chart, due to variability in the parameter estimation, might differ from known parameters’ case. This article explored the effect of estimated parameters on the conditional and marginal performance of the geometric-Poisson EWMA chart. The run length characteristics are calculated using a Markov chain approach and the effect of estimation on the performance of the given chart is shown to be significant. Recommendations about the proposer choice of sample size, smoothing constant, and dispersion parameter are made. Results of this study highlight the practical implications of estimation error, and to offer advice to practitioners when constructing/analyzing a phase-I sample.
Mathematical calculation model for geometrical parameters of timber mesh design with orthogonal grid
Directory of Open Access Journals (Sweden)
Loktev Dmitriy Aleksandrovich
Full Text Available Mesh cover design, a multi-element design, which ensures the correct geometrical arrangement of the elements, is a very important task. The purpose of the given article is the development of a mathematical model for selecting the geometric parameters of wooden arches with mesh orthogonal grid with different input data. In this article three variants of design were observed. The main differences between them are in the relative position of longitudinal and transverse components. When performing static calculations of such designs in order to achieve their subsequent correct assembly, the following location conditions were observed: all the items must strictly match with each other without a gap and without overlap. However, these conditions must be met for any ratio of height to the arch span, the number of longitudinal members and the thickness of longitudinal members. Inverse problems also take place. In this case, the geometric calculation is not possible to vary the cross-section elements, and the stress-strain state of the cover is provided by varying the pitch of the transverse arches of the elements, on which the geometric calculation has no influence. All this determines the need for universal mathematical models describing any geometrical parameter of the designs needed for their geometrical calculation. The basic approach for the development of such models is the use of the known trigonometric formulas, giving a complete description of the desired geometry of the arch. Finally three transcendental equations were obtained, the solution algorithm of which using Newton’s method is presented in the MathCAD. The complexity of solving such equations using the proposed algorithm in the MathCAD is reduced to a minimum.
Topology optimization with geometric uncertainties by perturbation techniques
DEFF Research Database (Denmark)
Lazarov, Boyan Stefanov; Schevenels, M.; Sigmund, Ole
2012-01-01
the above assumptions, the proposed algorithm provides a computationally cheap alternative to previously introduced stochastic optimization methods based on Monte Carlo sampling. The method is demonstrated on the design of a minimum compliance cantilever beam and a compliant mechanism. Copyright © 2012 John......The aim of this paper was to present a topology optimization methodology for obtaining robust designs insensitive to small uncertainties in the geometry. The variations are modeled using a stochastic field. The model can represent spatially varying geometry imperfections in devices produced...... by etching techniques. Because of under‐etching or over‐etching parts of the structure may become thinner or thicker than a reference design supplied to the manufacturer. The uncertainties are assumed to be small and their influence on the system response is evaluated using perturbation techniques. Under...
Directory of Open Access Journals (Sweden)
Bum-Joo Lee
2013-02-01
Full Text Available In this paper differential kinematics was geometrically derived to be utilized in a calibration algorithm that improves the accuracy of the manipulation of a robot. Even though the mechanical components are manufactured and assembled precisely, small differences between the designed and the actual system always exist, due to both geometric and unmodelled errors. In order to resolve these problems, differential relationships between the model parameters and the end‐effectorʹs posture were formulated. Subsequently, a derivative based estimation algorithm, such as an EKF (Extended Kalman Filter manner, could be adopted to update the model parameters. The proposed algorithm includes joint flexibility, so is an advanced version of previous work, where a rigid joint model was adopted [1]. The effectiveness of the proposed algorithm was verified by a computer simulation with a 6 DOF manipulator robot.
Absolute and geometric parameters of W UMa type contact binary TYC 1174-344-1
Gürol, B.; Derman, E.; Saguner, T.; Gürsoytrak, S. H.; Terzioğlu, Z.; Gökay, G.; Demircan, Y.; Okan, A.; Saral, G.
2011-07-01
We present the results of our investigation on the geometrical and physical parameters of W UMa-type binary TYC1174-344-1 from analyzed CCD (BVRI) light curves and radial velocity data. The photometric data were obtained in 2009 at Ankara University Observatory (AUO) and the spectroscopic observations were made in 2008 at Astrophysical Observatory of Asiago (Italy). Light and radial velocity observations were analyzed simultaneously by using the well-known Wilson-Devinney (2007 revision) code to obtain absolute and geometrical parameters. According to our solutions, the system is found to be a low mass-ratio A-type W UMa system. Combining our photometric solution with the spectroscopic data, we derived mass and radii of the eclipsing system as M1 = 1.381 M ⊙, M2 = 0.258 M ⊙, R1 = 1.449 R ⊙ and R2 = 0.714 R ⊙. We finally discussed the evolutionary condition of the system.
Directory of Open Access Journals (Sweden)
N. Dammak
2010-01-01
Full Text Available Problem statement: The objective of this study was to optimize the geometrical parameters of a bubble pump integrated in a solar flat plate collector. Approach: This solar bubble pump was part of an ammonia/water/helium (NH3/H2O/He absorption-diffusion cooling system. Results: An empirical model was developed on the basis of momentum, mass, material equations and energy balances. The mathematical model was solved using the simulation tool Engineering Equation Solver (EES. Conclusion/Recommendations: Using metrological data from Gabes (Tunisia various parameters were geometrically optimized for maximum bubble pump efficiency which was best for a bubble pump tube diameter of 6 mm, a tube length of 1.5 m, an inclination to the horizontal between 30 and 50° of the solar flat plate collector and a submergence ratio between 0.2 and 0.3.
Directory of Open Access Journals (Sweden)
Bum-Joo Lee
2013-02-01
Full Text Available In this paper differential kinematics was geometrically derived to be utilized in a calibration algorithm that improves the accuracy of the manipulation of a robot. Even though the mechanical components are manufactured and assembled precisely, small differences between the designed and the actual system always exist, due to both geometric and unmodelled errors. In order to resolve these problems, differential relationships between the model parameters and the end-effector's posture were formulated. Subsequently, a derivative based estimation algorithm, such as an EKF (Extended Kalman Filter manner, could be adopted to update the model parameters. The proposed algorithm includes joint flexibility, so is an advanced version of previous work, where a rigid joint model was adopted [1]. The effectiveness of the proposed algorithm was verified by a computer simulation with a 6 DOF manipulator robot.
DEFF Research Database (Denmark)
Putzer, Michael; Rasmussen, John; Penzkofer, Rainer
Body Modeling System and a parameterized musculoskeletal lumbar spine model for four different postures: upright standing, flexion (50°), torsion (10°) and lateral bending (15°). The linear dimensions of the vertebral body, the posterior parts of the vertebrae as well as the disc height, the orientation...... of the facet joints and the curvature of the lumbar spine have been varied. Figure 1 depicts the used musculoskeletal model in the flexed posture and a lumbar vertebra labeled with all relevant linear dimensions except the disc height. Additionally, all combinations of the three parameters vertebral body......Musculoskeletal simulations of subject-specific loads in the lumbar spine are computed by using subject-specific geometrical data. However this data has an inherent inaccuracy. This study evaluates the influence of defined geometrical parameters on lumbar spine loading utilizing the Any...
Optimization of the blade trailing edge geometric parameters for a small scale ORC turbine
Zhang, L.; Zhuge, W. L.; Peng, J.; Liu, S. J.; Zhang, Y. J.
2013-12-01
In general, the method proposed by Whitfield and Baines is adopted for the turbine preliminary design. In this design procedure for the turbine blade trailing edge geometry, two assumptions (ideal gas and zero discharge swirl) and two experience values (WR and γ) are used to get the three blade trailing edge geometric parameters: relative exit flow angle β6, the exit tip radius R6t and hub radius R6h for the purpose of maximizing the rotor total-to-static isentropic efficiency. The method above is established based on the experience and results of testing using air as working fluid, so it does not provide a mathematical optimal solution to instruct the optimization of geometry parameters and consider the real gas effects of the organic, working fluid which must be taken into consideration for the ORC turbine design procedure. In this paper, a new preliminary design and optimization method is established for the purpose of reducing the exit kinetic energy loss to improve the turbine efficiency ηts, and the blade trailing edge geometric parameters for a small scale ORC turbine with working fluid R123 are optimized based on this method. The mathematical optimal solution to minimize the exit kinetic energy is deduced, which can be used to design and optimize the exit shroud/hub radius and exit blade angle. And then, the influence of blade trailing edge geometric parameters on turbine efficiency ηts are analysed and the optimal working ranges of these parameters for the equations are recommended in consideration of working fluid R123. This method is used to modify an existing ORC turbine exit kinetic energy loss from 11.7% to 7%, which indicates the effectiveness of the method. However, the internal passage loss increases from 7.9% to 9.4%, so the only way to consider the influence of geometric parameters on internal passage loss is to give the empirical ranges of these parameters, such as the recommended ranges that the value of γ is at 0.3 to 0.4, and the value
Simulation of mechanisms modeled by geometrically-exact beams using Rodrigues rotation parameters
Gay Neto, Alfredo
2017-03-01
We present mathematical models for joints, springs, dashpots and follower loads, to be used together with geometrically-exact beam finite elements to simulate mechanisms. The rotations are described using Rodrigues parameters. An updated-Lagrangian approach is employed, leading to the possibility of finite rotations involving many turns, overcoming possible singularities in the rotation tensor. We present formulations for spherical, hinge and universal (Cardan) joints, which are enforced by Lagrange multipliers. For the hinge joint, a torsional spring with a nonlinear damper model is presented. A geometric-nonlinear translational spring/dashpot model is proposed, such as follower loads. All formulations are presented detailing their contribution to the model weak form and tangent operator. These are employed together with implicit time-integration schemes. Numerical examples are performed, showing that the proposed formulations are able to model complex spatial mechanisms. Usage of the models together with contact interaction between beams is explored by a cam/follower mechanism example.
Mohamed Abouelyazied Abdallh, Ahmed; Crevecoeur, Guillaume; Dupré, Luc
2011-01-01
The magnetic properties of the magnetic circuit of an electromagnetic device (EMD) can be identified by solving an inverse problem, where sets of measurements are properly interpreted using a forward numerical model of the device. However, the uncertainties of the geometrical parameter values in the forward model result in recovery errors in the reconstructed material parameter values. This paper proposes a novel inverse approach technique, in which the propagations of the uncertainties in th...
Penta, Francesco; Rossi, Cesare; Savino, Sergio
2016-06-01
This study aims to optimize the geometrical parameters of an under-actuated mechanical finger by conducting a theoretical analysis of these parameters. The finger is actuated by a flexion tendon and an extension tendon. The considered parameters are the tendon guide positions with respect to the hinges. By applying such an optimization, the correct kinematical and dynamical behavior of the closing cycle of the finger can be obtained. The results of this study are useful for avoiding the snapthrough and the single joint hyperflexion, which are the two breakdowns most frequently observed during experimentation on prototypes. Diagrams are established to identify the optimum values for the tendon guides position of a finger with specified dimensions. The findings of this study can serve as guide for future finger design.
Hadaś, E.; Borkowski, A.; Estornell, J.
2016-06-01
The estimation of dendrometric parameters has become an important issue for the agricultural planning and management. Since the classical field measurements are time consuming and inefficient, Airborne Laser Scanning (ALS) data can be used for this purpose. Point clouds acquired for orchard areas allow to determine orchard structures and geometric parameters of individual trees. In this research we propose an automatic method that allows to determine geometric parameters of individual olive trees using ALS data. The method is based on the α-shape algorithm applied for normalized point clouds. The algorithm returns polygons representing crown shapes. For points located inside each polygon, we select the maximum height and the minimum height and then we estimate the tree height and the crown base height. We use the first two components of the Principal Component Analysis (PCA) as the estimators for crown diameters. The α-shape algorithm requires to define the radius parameter R. In this study we investigated how sensitive are the results to the radius size, by comparing the results obtained with various settings of the R with reference values of estimated parameters from field measurements. Our study area was the olive orchard located in the Castellon Province, Spain. We used a set of ALS data with an average density of 4 points m-2. We noticed, that there was a narrow range of the R parameter, from 0.48 m to 0.80 m, for which all trees were detected and for which we obtained a high correlation coefficient (> 0.9) between estimated and measured values. We compared our estimates with field measurements. The RMSE of differences was 0.8 m for the tree height, 0.5 m for the crown base height, 0.6 m and 0.4 m for the longest and shorter crown diameter, respectively. The accuracy obtained with the method is thus sufficient for agricultural applications.
Mohammad Jafari; Hossein Afshin; Bijan Farhanieh; Atta Sojoudi
2016-01-01
Aerodynamic performance of a Bladeless fan is numerically investigated considering the effect of five geometric parameters. Airflow through this fan was analyzed by simulating a Bladeless fan within a 2 m × 2 m × 4 m room. Analysis of the flow field inside the fan and the evaluation of its performance were obtained by solving conservations of mass and momentum equations for the aerodynamic investigations. In order to design the Bladeless fan an Eppler 473 airfoil profile was used as the cross...
Visualization and on line monitoring of geometric parameters of beams at KSRS
Ioudin, L; Potlovsky, K; Rezvov, V
2001-01-01
On the basis of developed hardware and software we investigate the opportunity of on line registration of geometric parameters of low intensity SR beam and electron beams in single shot mode. Ionization and luminescence detectors form real optic image of a beam cross section. The image is registered by a TV camera, digitized and processed by a computer. Gray scale image and profiles of a beam are represented. Accumulation and statistic processing of the data give the possibility to increase the sensitivity of the hardware and to calculate the average position of the beam gravity center, dispersion and statistic uncertainty.
sprotocols
2015-01-01
Authors: David Hevia, Aida Rodriguez-Garcia, Marta Alonso-Gervós, Isabel Quirós-González, Henar M Cimadevilla, Carmen Gómez-Cordovés, Rosa M Sainz & Juan C Mayo ### Abstract The protocol reported here describes a simple, easy, fast and reproducible method aimed to know the geometric parameters of living cells based on confocal laser scanning microscopy combined with 3D reconstruction software. Briefly, the method is based on intrinsic fluorescence properties of acridine orange (AO...
The on-orbit calibration of geometric parameters of the Tian-Hui 1 (TH-1) satellite
Wang, Jianrong; Wang, Renxiang; Hu, Xin; Su, Zhongbo
2017-02-01
The on-orbit calibration of geometric parameters is a key step in improving the location accuracy of satellite images without using Ground Control Points (GCPs). Most methods of on-orbit calibration are based on the self-calibration using additional parameters. When using additional parameters, different number of additional parameters may lead to different results. The triangulation bundle adjustment is another way to calibrate the geometric parameters of camera, which can describe the changes in each geometric parameter. When triangulation bundle adjustment method is applied to calibrate geometric parameters, a prerequisite is that the strip model can avoid systematic deformation caused by the rate of attitude changes. Concerning the stereo camera, the influence of the intersection angle should be considered during calibration. The Equivalent Frame Photo (EFP) bundle adjustment based on the Line-Matrix CCD (LMCCD) image can solve the systematic distortion of the strip model, and obtain high accuracy location without using GCPs. In this paper, the triangulation bundle adjustment is used to calibrate the geometric parameters of TH-1 satellite cameras based on LMCCD image. During the bundle adjustment, the three-line array cameras are reconstructed by adopting the principle of inverse triangulation. Finally, the geometric accuracy is validated before and after on-orbit calibration using 5 testing fields. After on-orbit calibration, the 3D geometric accuracy is improved to 11.8 m from 170 m. The results show that the location accuracy of TH-1 without using GCPs is significantly improved using the on-orbit calibration of the geometric parameters.
Influence of geometrical parameters on performance of plasma synthetic jet actuator
Zong, Hao-hua; Wu, Yun; Jia, Min; Song, Hui-min; Liang, Hua; Li, Ying-hong; Zhang, Zhi-bo
2016-01-01
Plasma synthetic jet actuator (PSJA) has shown wide and promising application prospects in a high speed flow control field, due to its rapid response, high exhaust velocity, and non-moving components. In this paper, the total pressure profile of a plasma synthetic jet (PSJ) is measured and a new method is developed to evaluate the pulsed thrust of the PSJA. The influence of geometrical parameters including the electrode distance, the orifice diameter, and the throat length on PSJA performance is analyzed based on the pulsed thrust, the discharge characteristics, and the schlieren images. When varying the electrode distance, the dominant factor determining the jet intensity is the heating volume instead of the discharge energy. For the arc discharge, the electrode distance should be extended to increase both the jet velocity and the jet duration time. The design of the orifice diameter should be based on the controlled flow field. A large orifice diameter produces a strong perturbation with short time duration, while a small orifice diameter induces a lasting jet with low mass flux. In order to obtain better high frequency performance, the throat length should be shortened on the condition that the structural strength of the PSJA is maintained, while there is almost no influence of the throat length on the single cycle performance of the PSJA. Once the discharge energy is fixed, the pulsed thrust remains almost unchanged with different orifice diameters and throat lengths. These three geometrical parameters are independent to some extent and can be optimized separately.
Geometric Parameters Estimation and Calibration in Cone-Beam Micro-CT
Directory of Open Access Journals (Sweden)
Jintao Zhao
2015-09-01
Full Text Available The quality of Computed Tomography (CT images crucially depends on the precise knowledge of the scanner geometry. Therefore, it is necessary to estimate and calibrate the misalignments before image acquisition. In this paper, a Two-Piece-Ball (TPB phantom is used to estimate a set of parameters that describe the geometry of a cone-beam CT system. Only multiple projections of the TPB phantom at one position are required, which can avoid the rotation errors when acquiring multi-angle projections. Also, a corresponding algorithm is derived. The performance of the method is evaluated through simulation and experimental data. The results demonstrated that the proposed method is valid and easy to implement. Furthermore, the experimental results from the Micro-CT system demonstrate the ability to reduce artifacts and improve image quality through geometric parameter calibration.
Effects of laser parameters on the geometrical characteristics of peg-shaped bionic coupling unit
Zhang, Baoyu; Zhang, Zhihui; Liang, Yunhong; Yan, Qiongqiong; Ren, Luquan
2014-12-01
Peg-shaped bionic coupling unit (PBCU) processed by pulse laser is effective in anti-adhesion, anti-drag, anti-wear and anti-fatigue application. To obtain desired structural and morphological characteristics of the PBCU for industrial manufacturing, selection of proper processing parameters gradually becomes a growing important problem. Traditionally, the procedure of parameter selecting is often cost-plus and time-consuming. In this work, a statistical analysis of fabricating PBCU on the surface of medium carbon steel was conducted. The laser processing parameters utilized in the experiment and analysis are peak power 4-8 kW, pulse duration 6-16 ms and defocusing amount 6-10 mm. A series of mathematical models regarding the relationship between geometrical characteristics of PBCU and laser processing parameters were developed and checked. The results indicate that the developed models can be adequately used to control the structural and morphological characteristics of PBCU within the scope of analysis. Based on the models, the formation mechanism of the structural and morphological characteristics under different laser parameters were analyzed and discussed.
Directory of Open Access Journals (Sweden)
Danuta Wiss
2012-10-01
Full Text Available The ratio of primordium size to the meristem size (P/M ratio is regarded by some geometrical models of phyllotaxis as the parameter, which determines the quality of spiral and whorled patterns of lateral organ arrangement. This assumption was tested on floral meristems in four genets representing four Magnolia taxa: M. × salicifolia, M. stellata, M. denudata and M. acuminata. In successive zones of Magnolia flower, lateral organs are initiated in specific phyllotactic patterns and at specific values of the meristem and primordia sizes. The elements of perianth, usually positioned in three trimerous whorls, are initiated as large primordia on relatively small meristem. The switch in the identity of primordia, from tepals to stamens is accompanied by an abrupt increase in the size of the meristem and decrease in the primordia size. Small values of P/M ratio and frequent occurrence of qualitative transformations of phyllotaxis contribute to the exceptionally rich spectrum of spiral patterns in androecium zone. New spiral patterns emerge when bigger primordia of carpels are initiated on the meristem, which at the same time starts diminishing in size either abruptly (M. × salicifolia, M. stellata, M. acuminata or slowly (M. denudata. Spiral patterns identified in gynoecia have lower numbers of parastichies than the patterns of androecia and occur in frequencies specific for the genet. Although noted ranges of the meristem and primordia sizes, justify the occurrence of phyllotactic patterns observed in successive zones of Magnolia flower, they do not explain genet-specific frequencies of the patterns observed in gynoecium zone. The lack of straightforward relationship between frequency of the patterns and P/M ratio in gynoecium suggests that more complex geometrical factors or factors of non-geometrical nature are engaged in determination of Magnolia floral phyllotaxis.
Noncoherent sampling technique for communications parameter estimations
Su, Y. T.; Choi, H. J.
1985-01-01
This paper presents a method of noncoherent demodulation of the PSK signal for signal distortion analysis at the RF interface. The received RF signal is downconverted and noncoherently sampled for further off-line processing. Any mismatch in phase and frequency is then compensated for by the software using the estimation techniques to extract the baseband waveform, which is needed in measuring various signal parameters. In this way, various kinds of modulated signals can be treated uniformly, independent of modulation format, and additional distortions introduced by the receiver or the hardware measurement instruments can thus be eliminated. Quantization errors incurred by digital sampling and ensuing software manipulations are analyzed and related numerical results are presented also.
Noncoherent sampling technique for communications parameter estimations
Su, Y. T.; Choi, H. J.
1985-01-01
This paper presents a method of noncoherent demodulation of the PSK signal for signal distortion analysis at the RF interface. The received RF signal is downconverted and noncoherently sampled for further off-line processing. Any mismatch in phase and frequency is then compensated for by the software using the estimation techniques to extract the baseband waveform, which is needed in measuring various signal parameters. In this way, various kinds of modulated signals can be treated uniformly, independent of modulation format, and additional distortions introduced by the receiver or the hardware measurement instruments can thus be eliminated. Quantization errors incurred by digital sampling and ensuing software manipulations are analyzed and related numerical results are presented also.
Earth rotation parameters from satellite techniques
Thaller, Daniela; Beutler, Gerhard; Jäggi, Adrian; Meindl, Michael; Dach, Rolf; Sosnica, Krzysztof; Baumann, Christian
2013-04-01
It has been demonstrated since several years that satellite techniques are capable of determining Earth Rotation Parameters (ERPs) with a daily or even sub-daily resolution. Especially Global Navigation Satellite Systems (GNSS) with their huge amount of observations can determine time series of polar motion (PM) and length of day (LOD) rather well. But also SLR with its spherical satellites whose orbital motions are easy to model and that allow long orbital arc lengths can deliver valuable contributions to Earth rotation. We analyze GNSS solutions (using GPS and GLONASS) and SLR solutions (using LAGEOS) regarding their potential of estimating polar motion and LOD with daily and subdaily temporal resolution. A steadily improving modeling applied in the analysis of space-geodetic data aims at improved time series of geodetic parameters, e.g., the ERPs. The Earth's gravity field and especially its temporal variations are one point of interest for an improved modeling for satellite techniques. For modeling the short-periodic gravity field variations induced by mass variations in the atmosphere and the oceans the GRACE science team provides the Atmosphere and Ocean Dealiasing (AOD) products. They contain 6-hourly gravity fields of the atmosphere and the oceans. We apply these corrections in the analysis of satellite-geodetic data and show the impact on the estimated ERPs. It is well known that the degree-2 coefficients of the Earth's gravity field are correlated with polar motion and LOD. We show to what extent temporal variations in the degree-2 coefficients are influencing the ERP estimates.
Directory of Open Access Journals (Sweden)
Mohammad Jafari
2016-03-01
Full Text Available Aerodynamic performance of a Bladeless fan is numerically investigated considering the effect of five geometric parameters. Airflow through this fan was analyzed by simulating a Bladeless fan within a 2 m × 2 m × 4 m room. Analysis of the flow field inside the fan and the evaluation of its performance were obtained by solving conservations of mass and momentum equations for the aerodynamic investigations. In order to design the Bladeless fan an Eppler 473 airfoil profile was used as the cross section of the fan. Five distinct parameters, namely height of cross section of the fan, outlet angle of the flow relative to the fan axis, thickness of airflow outlet slit, hydraulic diameter, and aspect ratio for circular and quadratic cross sections were considered. Validating 3-D numerical results, experimental results of a round jet showed good agreement with those of the simulation data. The multiplier factor M is defined to show the ratio of the outlet flow rate to inlet flow rate from the fan. The obtained numerical results showed that the Discharge ratio has the maximum value for the height of 3 cm. The numerical outcomes of outlet thickness variation indicate that this parameter is one of the most influential parameters on the aerodynamic performance of a Bladeless fan. The results for the outlet thicknesses of 1, 2 and 3 mm showed that the Discharge ratio increased significantly when the outlet thickness decreased.
Directory of Open Access Journals (Sweden)
M. G. Kiselev
2016-01-01
Full Text Available The paper contains an analysis of dimple geometric parameters obtained on wire surface during its in its electrical discharge machining. A photography and description of one of the dimples has been given in the paper. The paper has analyzed a cross-sectional shape of the obtained dimple with due account of the solidified metal flows formed along its edges. The flows in a first approximation can be considered as elements of a cutting wedge. According to cutting theory provisions the paper considers solidified metal flow shapes in a longitudinal section and indicates angles which have been formed by the flows, working planes and edges which can be involved in the cutting process. It has been shown that cutting elements on the dimple surface are arranged symmetrically that makes it possible to carry out cutting process while moving a tool in both directions of reciprocating motion. Parameters of cutting surface influencing on cutting process execution have been specified in the paper. It has been demonstrated that due to changes in energy of electric discharge through voltage or capacity of a power supply storage capacitor it is possible purposefully to influence on the shape and size of metal flows and, respectively, on values of cutting wedge parameters that characterize a tool cutting ability. A conclusion has been made about possibility to obtain the most advantageous values of these parameters while optimizing modes of wire electrical discharge machining.
The effects of rock joint geometrical parameters on safety of concrete arch dam abutments
Energy Technology Data Exchange (ETDEWEB)
Yazdani, S.; Yazdani, M.; Joorabchi, A.E. [Tarbiat Modares Univ., Tehran (Iran, Islamic Republic of)
2007-07-01
The International Commission on Large Dams (ICOLD) has stated that foundation failure is the primary cause of dam failure following overtopping. As such, concrete arch dams require strong and stiff abutments. The failure of jointed rock mass at abutments is one of the key mechanisms that may lead to uncontrolled leakage. For that reason, this study investigated the affect of the joint geometrical parameters on the stability of the concrete arch dam abutments. The study also considered the role of joints on the behaviour mechanism of rock mass because it is governed by mechanical and hydraulic properties. The orientation of joints was considered since kinematic conditions are needed for a block to move. The hydromechanical influence of joint apertures on the stability of the foundation was also investigated through nonlinear analyses of different joint orientations and apertures on a hypothetical jointed abutment. Dam abutment safety was estimated by finding the values of maximum sliding and maximum opening and determining the water flow along discontinuities. The values of these 3 indices were derived for different orientations of joints. It was concluded that abutment safety was highly dependent on the geometrical characteristics of joints. 8 refs., 1 tab., 6 figs.
Axinte, Andrei; Taranu, Nicolae; Bejan, Liliana
2016-10-01
A polymer fabric reinforced composite is a high performance material, which combines strength of the fibres with the flexibility and ductility of the matrix. For a better drapeability, the tows of fibres are interleaved, resulting the woven fabric, used as reinforcement. The complex geometric shape of the fabric is of paramount importance in establishing the deformability of the textile reinforced composite laminates. In this paper, an approach based on Classical Lamination Theory ( CLT), combined with Finite Element Methods ( FEM), using Failure Analysis and Internal Load Redistribution, is utilised, in order to compare the behaviour of the material under specific loads. The main goal is to analyse the deformability of certain types of textile reinforced composite laminates, using carbon fibre satin as reinforcement and epoxy resin as matrix. This is accomplished by studying the variation of the in-plane strains, given the fluctuation of several geometric parameters, namely the width of the reinforcing tow, the gap between two consecutive tows, the angle of laminae in a multi-layered configuration and the tows fibre volume fraction.
TECHNOLOGICAL IMPERFECTIONS OF FORCE ROD GEOMETRICAL PARAMETERS FOR PANDA OPTICAL FIBERS PRODUCTION
Directory of Open Access Journals (Sweden)
N. V. Semenov
2014-01-01
Full Text Available The paper deals with the dependence in radial dimensions changes of the workpieces on the angular coordinate based on experimental data about the geometry of the cross-sections of force rods batch for the production of anisotropic Panda-type optical fibers. An algorithm of geometrical parameters statistical processing is described, which gives the possibility to find the similarity in the geometry of the cross-sections of different force rods, and reveal the characteristic shape of the crosssection for all the samples. The algorithm contains the shift of points for dependence changes in radial dimensions of the workpieces on the angular coordinate in order to find curves with maximum correlation coefficient. Afterwards, the distribution of the radius values for each angular coordinate is found basing on the obtained curves. It is demonstrated that in case of the force rods production with variable amount of alloying dopes on the radius via the MCVD method, it is impossible to get
Tirumala, Rakshit; Benard, Nicolas; Moreau, Eric; Fenot, Matthieu; Lalizel, Gildas; Dorignac, Eva
2014-06-01
Dielectric barrier discharge (DBD) based surface plasma actuators have been well studied as flow manipulation devices. However, there is a dearth of research on their application for convective heat transfer enhancement. The adoption of DBD actuators to such areas requires a detailed study on the thermal characteristics of the plasma discharge. The present study conducts infrared thermography measurements on the surface of a thick dielectric (2-4 mm) based DBD actuator and characterizes it against various electrical and geometrical parameters. The temperature distribution is also studied in relation to the regimes of the discharge cycle through comparison with intensified charge-coupled device (iCCD) imaging. Measurements are also conducted with thin cylindrical electrode (wire) based configurations to study the influence of streamer inhibition. Based on the observed experimental results, a hypothesis is proposed on the mechanism of dielectric heating and the relationship between dielectric surface temperature and gas temperature.
Geometrical track parameters in the pallasite olivine: Identification of the cosmic ray heavy nuclei
Energy Technology Data Exchange (ETDEWEB)
Kashkarov, L.L. [Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Kosygin Str. 19, Moscow 119991 (Russian Federation)], E-mail: cosmo@geokhi.ru; Polukhina, N.G.; Starkov, N.I. [Lebedev Physical Institute, Russian Academy of Sciences, Leninskii pr. 53, Moscow 119991 (Russian Federation); Kalinina, G.V.; Ivliev, A. [Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Kosygin Str. 19, Moscow 119991 (Russian Federation); Aleksandrov, A.B.; Goncharova, L.A.; Tarasova, I. Yu. [Lebedev Physical Institute, Russian Academy of Sciences, Leninskii pr. 53, Moscow 119991 (Russian Federation)
2008-08-15
The geometry characteristics of chemically etched tracks in the not annealed olivine crystals from pallasite meteorites are investigated with the search and identification goal of fossil tracks of galactic cosmic ray heavy and superheavy nuclei. The chosen methodology is based on precise measurements of the nucleus track parameters in the course of chemical etching of the olivine crystals. Geometric parameters of individual tracks are traced and measured in course of their step-by-step chemical etching by using a modern high-precision, completely automated facility PAVICOM designed at the Lebedev Physical Institute of Russian Academy of Sciences. A method of the layer-by-layer removal of olivine material is employed, which allows the tracks to be studied over the whole crystal volume under study. It is planned to measure the next main parameters: the cone length and diameters of etched track within the initial, high-energy section of its formation; the total residual range and diameters, corresponding to saturation zone of the primary ionization; and the etching rate along the different parts of tracks, the starting inter-volume olivine crystal point for which were fixed. The preliminary experimental results obtained for 42 tracks, detected and analyzed in the Marjalahti pallasite olivine crystals, are presented.
Hyperspectral Technique for Detecting Soil Parameters
Garfagnoli, F.; Ciampalini, A.; Moretti, S.; Chiarantini, L.
2011-12-01
In satellite and airborne remote sensing, hyperspectral technique has become a very powerful tool, due to the possibility of rapidly realizing chemical/mineralogical maps of the studied areas. Many studies are trying to customize the algorithms to identify several geo-physical soil properties. The specific objective of this study is to investigate those soil characteristics, such as clay mineral content, influencing degradation processes (soil erosion and shallow landslides), by means of correlation analysis, in order to examine the possibility of predicting the selected property using high-resolution reflectance spectra and images. The study area is located in the Mugello basin, about 30 km north of Firenze (Tuscany, Italy). Agriculturally suitable terrains are assigned mainly to annual crops, marginally to olive groves, vineyards and orchards. Soils mostly belong to Regosols and Cambisols orders. An ASD FieldSpec spectroradiometer was used to obtain reflectance spectra from about 80 dried, crushed and sieved samples under controlled laboratory conditions. Samples were collected simultaneously with the flight of SIM.GA hyperspectral camera from Selex Galileo, over an area of about 5 km2 and their positions were recorded with a differential GPS. The quantitative determination of clay minerals content was performed by means of XRD and Rietveld refinement. Different chemometric techniques were preliminarily tested to correlate mineralogical records with reflectance data. A one component partial least squares regression model yielded a preliminary R2 value of 0.65. A slightly better result was achieved by plotting the absorption peak depth at 2210 versus total clay content (band-depth analysis). The complete SIM.GA hyperspectral geocoded row dataset, with an approximate pixel resolution of 0.6 m (VNIR) and 1.2 m (SWIR), was firstly transformed into at sensor radiance values, by applying calibration coefficients and parameters from laboratory measurements to non
Physical and geometrical parameters of CVBS X: the spectroscopic binary Gliese 762.1
Masda, Suhail G.; Al-Wardat, Mashhoor A.; Neuhäuser, Ralph; Al-Naimiy, Hamid M.
2016-07-01
We present the physical and geometrical parameters of the individual components of the close visual double-lined spectroscopic binary system Gliese 762.1, which were estimated using Al-Wardat's complex method for analyzing close visual binary systems. The estimated parameters of the individual components of the system are as follows: radius RA = 0.845 ± 0.09 R ⊙, RB = 0.795 ± 0.10 R ⊙, effective temperature TA eff = 5300 ± 50 K, TB eff = 5150 ± 50 K, surface gravity log gA = 4.52 ± 0.10, log gB = 4.54±0.15 and luminosity LA = 0.51±0.08 L ⊙, LB = 0.40±0.07 L ⊙. New orbital elements are presented with a semi-major axis of 0.0865 ± 0.010 arcsec using the Hippracos parallax π = 58.96 ± 0.65 mas, and an accurate total mass and individual masses of the system are determined as M = 1.72 ± 0.60 M⊙, MA = 0.89 ± 0.08 M ⊙ and MB = 0.83 ± 0.07 M⊙. Finally, the spectral types and luminosity classes of both components are assigned as K0V and K1.5V for the primary and secondary components respectively, and their positions on the H-R diagram and evolutionary tracks are given.
Directory of Open Access Journals (Sweden)
E. Huanca Cayo
2011-05-01
Full Text Available Purpose: Show the relationship between geometric characteristics of the weld bead and the optical-acoustic emissions from electric arc during welding in the GMAW-S process.Design/methodology/approach: Bead on plate welding experiments was carried out setting different process parameters. Every welding parameter group was set aiming to reach a high stability level what guarantee a geometrical uniformity in the weld beads. In each experiment was simultaneously acquired arc voltage, welding current, infrared and acoustic emissions; from them were computed parameters as arc power, acoustic peaks rate and infrared radiation rate. It was used a tri-dimensional LASER scanner for to acquire geometrical information from the weld beads surface as width and height of the bead. Depth penetration was measured from sectional cross cutting of weld beads.Findings: Previous analysis showed that the arc emission parameters reach a stationary state with different characteristic for each experiment group which means that there is some correlation level between them. Posterior analysis showed that from infrared parameter is possible to monitoring external weld bead geometry and principally its penetration depth. From acoustic parameter is possible to monitoring principally the external weld bead geometry. Therefore is concluded that there is a close relation between the arc emissions and the weld bead geometry and that them could be used to measuring the welding geometrical parameters.Research limitations/implications: After analysis it was noticed that the infrared sensing has a better performance than acoustic sensing in the depth penetration monitoring. Infrared sensing also sources some information about external geometric parameters that in conjunction with the acoustic sensing is possible to have reliable information about weld bead geometry. This method of sensing geometric parameters could be applied in other welding processes, but is necessary to have
Directory of Open Access Journals (Sweden)
Jayalakshmi
2014-03-01
Full Text Available Machining processes are met with dimensional and geometrical variations in a product during machining operation. The amount of variation needs to be more strictly defined for accurately machined parts. Geometric dimensioning and tolerancing (GD&T definition provides the precision required for allowing manufacturing of most economical parts. Crankshaft flange is required to be machined with higher degree of precision. If geometrical accuracies are not met the crankshaft-flywheel assembly will cause wear, unbalance and vibration, leading to poor functionality. The face of crankshaft flange is evaluated for geometric tolerances- flatness and runout. A two level three factor factorial model is designed and analyzed on Minitab 16 software to identify the most affecting machining parameter among speed, feed and depth of cut on face flatness and face runout.
Zhang, Yukun; Du, Jinglei; Wei, Xingzhan; Shi, Lifang; Deng, Qiling; Dong, Xiaochun; Du, Chunlei
2011-05-01
We have recently shown that patterns with 30 nm line width and micrometer scale periodicity could be steadily fabricated by employing localized surface plasmons lithography based on a soft mold [Opt. Lett. 35, 13 (2009)]. In this paper, the dependence of the resolution (pattern periodicity), critical dimension, and electric field intensity on the geometrical parameters of the soft mold, such as ridge width, mold periodicity, ridge depth, and slope, have been systematically studied and analyzed. The relevant simulation results by finite-difference time-domain demonstrate that the critical dimension exhibits a perfect stabilization and the value of electric field intensity would be especially large, when the ridge depth is in the range from 100 to 270 nm and the slope angle is below 35°. Importantly, the optimal resolution and critical dimension can reach 100 and 17 nm, respectively, by reasonably designing the corresponding mold periodicity and ridge width, which indicates that the method is particularly suitable for obtaining patterns with high density and is extremely promising for bio-sensing and photonic crystals application.
Numerical analysis of bypass model geometrical parameters influence on pulsatile blood flow
Directory of Open Access Journals (Sweden)
Jonášová A.
2011-06-01
Full Text Available The present study is focused on the analysis of pulsatile blood flow in complete idealized 3D bypass models in dependence on three main geometrical parameters (stenosis degree, junction angle and diameter ratio. Assuming the blood to be an incompressible Newtonian fluid, the non-linear system of Navier-Stokes equations is integrated in time by a fully implicit second-order accurate fractional-step method. The space discretization is performed with the help of the cell-centred finite volume method formulated for unstructured tetrahedral grids. In order to model a realistic coronary blood flow, a time-dependent flow rate taken from corresponding literature is considered. For the analysis of obtained numerical results, special emphasis is placed on their comparison in the form of velocity isolines at several selected cross-sections during systolic and diastolic phases. The remainder of this paper is devoted to discussion of walls shear stress distribution and its oscillatory character described by the oscillatory shear index with regard to areas prone to development of intimal hyperplasia or to thrombus formation.
Saha, Sourav; Mojumder, Satyajit; Mahboob, Monon; Islam, M. Zahabul
2016-07-01
Tungsten is a promising material and has potential use as battery anode. Tungsten nanowires are gaining attention from researchers all over the world for this wide field of application. In this paper, we investigated effect of temperature and geometric parameters (diameter and aspect ratio) on elastic properties of Tungsten nanowire. Aspect ratios (length to diameter ratio) considered are 8:1, 10:1, and 12:1 while diameter of the nanowire is varied from 1-4 nm. For 2 nm diameter sample (aspect ratio 10:1), temperature is varied (10K ~ 1500K) to observe elastic behavior of Tungsten nanowire under uniaxial tensile loading. EAM potential is used for molecular dynamic simulation. We applied constant strain rate of 109 s-1 to deform the nanowire. Elastic behavior is expressed through stress vs. strain plot. We also investigated the fracture mechanism of tungsten nanowire and radial distribution function. Investigation suggests peculiar behavior of Tungsten nanowire in nano-scale with double peaks in stress vs. strain diagram. Necking before final fracture suggests that actual elastic behavior of the material is successfully captured through atomistic modeling.
Physical and Geometrical Parameters of CVBS X: The Spectroscopic Binary Gliese 762.1
Masda, Suhail G; Neuhäuser, Ralph; Al-Naimiy, Hamid M
2016-01-01
We present the physical and geometrical parameters of the individual components of the close visual double-lined spectroscopic binary system Gliese 762.1, which were estimated using Al-Wardat's complex method for analyzing close visual binary systems. The estimated parameters of the individual components of the system are as follows: radius $R_{A}=0.845\\pm0.09 R_\\odot$, $R_{B}=0.795\\pm0.10 R_\\odot$, effective temperature $T_{\\rm eff}^{A} =5300\\pm50$\\,K, $T_{\\rm eff}^{B} =5150\\pm50$\\,K, surface gravity log $g_{A}=4.52\\pm0.10$, log $g_{B}=4.54\\pm0.15$ and luminosity $L_A=0.51\\pm0.08 L_\\odot$, $L_B=0.40\\pm0.07L_\\odot$. New orbital elements are presented with a semi-major axis of $0.0865 \\pm 0.010 $ arcsec using the Hippracos parallax $\\pi=58.96\\pm0.65$ mas, and an accurate total mass and individual masses of the system are determined as $M=1.72\\pm0.60M_\\odot$, $M_A=0.89 \\pm0.08M_\\odot$ and $M_B=0.83 \\pm0.07M_\\odot$. Finally, the spectral types and luminosity classes of both components are assigned as K0V and K1....
DEFF Research Database (Denmark)
Lee, Daniel Sang-Hoon; Naboni, Emanuele
2017-01-01
with light, sound and thermal conditions. It is considered that the characteristics of interferences would have close relationship with material and geometrical properties of the soffits; especially when the soffits are other than flat form. In the current investigation the relationship between the thermal......-sectioned beams. However, both flange and web are curved vertically for the required bending and shear capacity of the sections. At the same time, the web is also curved horizontally for increased shear capacities. In the research, both the vertical and horizontal geometrical parameters are varied to observe...
Li, Xiaoqiang; Han, Kai; Yu, Honghan; Zhang, Yongsheng; Li, Dongsheng
2016-08-01
Two point incremental forming receives widespread study with its advantages of economy and flexibility in small batch products, such as aircraft parts. Aircraft parts, however, are rigorous in their shape errors. In this paper, one real airplane part is selected and formed with different process parameters to investigate the shape error level of part. Comparing the geometric errors caused by different process parameters, such as tool diameter, step size, feed rate and tool path, it is found that the geometric errors reduce as tool diameter increases. Meanwhile, the effect of step size is not linear. Influence law of feed rate is various with different other parameters. The bidirectional tool path, having opposite processing direction at adjacent layer, reduces the errors.
Focused ion beam techniques for fabricating geometrically-complex components and devices.
Energy Technology Data Exchange (ETDEWEB)
Mayer, Thomas Michael; Adams, David Price; Hodges, V. Carter; Vasile, Michael J.
2004-03-01
We have researched several new focused ion beam (FIB) micro-fabrication techniques that offer control of feature shape and the ability to accurately define features onto nonplanar substrates. These FIB-based processes are considered useful for prototyping, reverse engineering, and small-lot manufacturing. Ion beam-based techniques have been developed for defining features in miniature, nonplanar substrates. We demonstrate helices in cylindrical substrates having diameters from 100 {micro}m to 3 mm. Ion beam lathe processes sputter-define 10-{micro}m wide features in cylindrical substrates and tubes. For larger substrates, we combine focused ion beam milling with ultra-precision lathe turning techniques to accurately define 25-100 {micro}m features over many meters of path length. In several cases, we combine the feature defining capability of focused ion beam bombardment with additive techniques such as evaporation, sputter deposition and electroplating in order to build geometrically-complex, functionally-simple devices. Damascene methods that fabricate bound, metal microcoils have been developed for cylindrical substrates. Effects of focused ion milling on surface morphology are also highlighted in a study of ion-milled diamond.
Energy Technology Data Exchange (ETDEWEB)
Dan Maljovec; Bei Wang; Valerio Pascucci; Peer-Timo Bremer; Diego Mandelli; Michael Pernice; Robert Nourgaliev
2013-10-01
and 2) topology-based methodologies to interactively visualize multidimensional data and extract risk-informed insights. Regarding item 1) we employ learning algorithms that aim to infer/predict simulation outcome and decide the coordinate in the input space of the next sample that maximize the amount of information that can be gained from it. Such methodologies can be used to both explore and exploit the input space. The later one is especially used for safety analysis scopes to focus samples along the limit surface, i.e. the boundaries in the input space between system failure and system success. Regarding item 2) we present a software tool that is designed to analyze multi-dimensional data. We model a large-scale nuclear simulation dataset as a high-dimensional scalar function defined over a discrete sample of the domain. First, we provide structural analysis of such a function at multiple scales and provide insight into the relationship between the input parameters and the output. Second, we enable exploratory analysis for users, where we help the users to differentiate features from noise through multi-scale analysis on an interactive platform, based on domain knowledge and data characterization. Our analysis is performed by exploiting the topological and geometric properties of the domain, building statistical models based on its topological segmentations and providing interactive visual interfaces to facilitate such explorations.
The Jump Set under Geometric Regularization. Part 1: Basic Technique and First-Order Denoising
Valkonen, Tuomo
2015-01-01
© 2015 Society for Industrial and Applied Mathematics. Let u ∈ BV(Ω) solve the total variation (TV) denoising problem with L^{2}-squared fidelity and data f. Caselles, Chambolle, and Novaga [Multiscale Model. Simul., 6 (2008), pp. 879-894] have shown the containment H^{m-1} (J
Oleksik, Valentin; Pascu, Adrian; Deac, Cristian; Fleaca, Radu; Roman, Mihai; Bologa, Octavian
2010-06-01
In this paper the authors intend to examine by numerical simulation one of the newest methods for obtaining the knee condylar surface, namely by incremental forming starting from a commercially pure titanium (CP Ti) sheet. In order to study the influence of the geometrical parameters, the authors chose to vary the material thickness, the punch diameter and the vertical step of the punch. Two different values of the hemispherical punch diameter (d = 4 and 6 mm), two different initial thicknesses of the blank (t = 1 and 1.2 mm) and two different vertical step values (s = 0.6 and 1 mm) are taken into consideration. The numerical results of the simulations were centered on determining the thinning of the sheet, the major principal strain, the springback, the process forces and the manner in which these are influenced by the geometrical parameters that were varied.
Radiation model for row crops: I. Geometric view factors and parameter optimization
Row crops with partial cover result in different radiation partitioning to the soil and canopy compared with full cover; however, methods to account for partial cover have not been adequately investigated. The objectives of this study were to: (i) develop geometric view factors to account for the sp...
Maji, Partha Sona
2014-01-01
We have performed a numerical analysis of the structural dependence of the PCF parameters towards ultra-flat dispersion in the C-band of communication wavelength. The technique is based on regular square-lattice PCF with all the air-hole of same uniform diameter and the effective size of the air-holes are modified with a selective infiltration of the air-holes with liquids. The dependence of the PCF structural parameters namely air-hole diameter and hole-to-hole distance along with the infiltrating liquid has been investigated in details. It is shown that the infiltrating liquid has critical influence on both the slope and value of dispersion, while pitch only changes the dispersion value whereas air-hole diameter modifies the slope of the dispersion. Our numerical investigation establishes dispersion values as small as 0+-0.58ps/(nm-km) over a bandwidth of 622nm in the communication wavelength band (C-band). The proposed design study will be very helpful in high power applications like broadband smooth super...
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L. Luquot
2015-11-01
Full Text Available The aim of this study is to compare the structural, geometrical and transport parameters of a limestone rock sample determined by X-ray microtomography (XMT images and laboratory experiments. Total and effective porosity, surface-to-volume ratio, pore size distribution, permeability, tortuosity and effective diffusion coefficient have been estimated. Sensitivity analyses of the segmentation parameters have been performed. The limestone rock sample studied here have been characterized using both approaches before and after a reactive percolation experiment. Strong dissolution process occured during the percolation, promoting a wormhole formation. This strong heterogeneity formed after the percolation step allows to apply our methodology to two different samples and enhance the use of experimental techniques or XMT images depending on the rock heterogeneity. We established that for most of the parameters calculated here, the values obtained by computing XMT images are in agreement with the classical laboratory measurements. We demonstrated that the computational porosity is more informative than the laboratory one. We observed that pore size distributions obtained by XMT images and laboratory experiments are slightly different but complementary. Regarding the effective diffusion coefficient, we concluded that both approaches are valuable and give similar results. Nevertheless, we wrapped up that computing XMT images to determine transport, geometrical and petrophysical parameters provides similar results than the one measured at the laboratory but with much shorter durations.
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O. V. Fomin
2013-10-01
Full Text Available Purpose. Presentation of features and example of the use of the offered determination algorithm of optimum geometrical parameters for the components of freight cars on the basis of the generalized mathematical models, which is realized using computer. Methodology. The developed approach to search for optimal geometrical parameters can be described as the determination of optimal decision of the selected set of possible variants. Findings. The presented application example of the offered algorithm proved its operation capacity and efficiency of use. Originality. The determination procedure of optimal geometrical parameters for freight car components on the basis of the generalized mathematical models was formalized in the paper. Practical value. Practical introduction of the research results for universal open cars allows one to reduce container of their design and accordingly to increase the carrying capacity almost by100 kg with the improvement of strength characteristics. Taking into account the mass of their park this will provide a considerable economic effect when producing and operating. The offered approach is oriented to the distribution of the software packages (for example Microsoft Excel, which are used by technical services of the most enterprises, and does not require additional capital investments (acquisitions of the specialized programs and proper technical staff training. This proves the correctness of the research direction. The offered algorithm can be used for the solution of other optimization tasks on the basis of the generalized mathematical models.
Geometrical design parameters for journal bearings with flexure pads and compliant liners
DEFF Research Database (Denmark)
Thomsen, Kim; Klit, Peder
2012-01-01
A hydrodynamic journal bearing utilizing flexure pads with a compliant liner is studied and its performance enhanced through a parametric study. The main geometrical dimensions are varied and the affect on pad performance is analyzed. This will put more knowledge into the design and function...... of flexure pads. uidelines are given to the design of the pads and are also covering the polymer liner. It is found that the use of flexure pads is an attractive alternative to pivoted pads. Pivot contact-related failure modes are eliminated and load capacity is not restricted by the force that can...
AUPERRIN, Audrey; Delille, Rémi; LESUEUR, Denis; BRUYERE, Karine; Masson, Catherine; Drazetic, Pascal
2014-01-01
The present study aims at providing quantitative data for the personalisation of geometrical and 21 mechanical characteristics of the adult cranial bone to be applied to head FE models. A set of 351 22 cranial bone samples, harvested from 21 human skulls, were submitted to three-point bending tests 23 at 10 mm/min. For each of them, an apparent elastic modulus was calculated using the beam's 24 theory and a density-dependant beam inertia. Thicknesses, apparent densities and percentage of ash ...
CT measurement of acetabulum geometric parameter%髋臼几何参数的CT测量
Institute of Scientific and Technical Information of China (English)
胡荣慧; 贺斌; 刘力; 严睿; 刘嘉凯; 黄小波; 张剑; 丁薇
2013-01-01
背景：近年来尽管对髋臼形态特征的研究已经取得了一些成果，但由于髋臼结构和位置的特殊性，有关髋臼表面形态的定量描述至今尚未统一，这势必会影响髋关节病变诊断和治疗的准确性。目的：探讨髋臼几何参数的CT测量方法。方法：选取70例髋关节CT受检者，其中正常成人50例(两侧共100个髋关节)，单侧先天性髋关节脱位患儿20例。对所有受检者髋关节CT图像进行冠状面重建和三维重建，比较正常成人髋臼上外倾角冠状位和三维测值，比较先天性髋关节脱位组患侧与正常侧髋臼上外倾角。选择配伍组设计方差分析，分别比较扫描床面为参照面和以身体冠状面为参照面测量左右侧髋臼后外展角、前髋臼指数及后髋臼指数。结果与结论：髋臼上外倾角在冠状位测值为(39.99±6.1)°，在三维图像上测值为(40.13±5.80)°，2者比较，差异无显著性意义(P >0.05)。先天性髋关节脱位患儿双侧上外倾角在冠状面的测量值，正常侧为(48.95±3.80)°，脱位侧为(63.56±6.35)°，二者之间差异有非常显著性意义(P 0.05)。提示以冠状面为参照平面测量双侧后外展角和前、后髋臼指数准确可靠，可客观反映髋臼情况，为髋关节区病变的诊断和治疗提供确切的量化指标。% BACKGROUND: Although, the previous studies on acetabular morphological characteristics have yielded some results, quantitative description of the acetabular surface morphology has not yet been unified because of the special nature of acetabular structure and location, and this is bound to affect the accuracy of the diagnosis and treatment of hip disease. OBJECTIVE: To investigate the CT measuring methods to acetabulum geometric parameters. METHODS: Seventy cases performed CT scan were selected, including 50 normal adults (a total of 100 hips on both sides) and 20 cases with unilateral congenital
Aminfar, Ali; Mojtahedi, Alireza; Ahmadi, Hamid; Aminfar, Mohammad Hossain
2017-06-01
Among numerous offshore structures used in oil extraction, jacket platforms are still the most favorable ones in shallow waters. In such structures, log piles are used to pin the substructure of the platform to the seabed. The pile's geometrical and geotechnical properties are considered as the main parameters in designing these structures. In this study, ANSYS was used as the FE modeling software to study the geometrical and geotechnical properties of the offshore piles and their effects on supporting jacket platforms. For this purpose, the FE analysis has been done to provide the preliminary data for the fuzzy-logic post-process. The resulting data were implemented to create Fuzzy Inference System (FIS) classifications. The resultant data of the sensitivity analysis suggested that the orientation degree is the main factor in the pile's geometrical behavior because piles which had the optimal operational degree of about 5° are more sustained. Finally, the results showed that the related fuzzified data supported the FE model and provided an insight for extended offshore pile designs.
Effect of geometrical parameters of open microchannel surfaces on pool boiling heat transfer
Directory of Open Access Journals (Sweden)
Kaniowski Robert
2017-01-01
Full Text Available This study focuses on the effect of channel depth on the heat transfer coefficient during nucleate pool boiling. Experimental studies were performed for saturated deionized water, and Novec-649 as working fluids at atmospheric pressure. Copper surfaces were modified to form microchannels with different geometrical properties. The microchannels were from 0.2 mm to 0.4 mm deep, 0.3 mm wide and spaced every 0.1 mm. The experiment was conducted for increasing heat flux up to the critical heat flux point. The surface modification provided an appreciably higher heat transfer coefficient compared to the smooth surface for all boiling liquids. The maximum heat transfer coefficient obtained exceeded 60 kW/m2K.
Auperrin, Audrey; Delille, Rémi; Lesueur, Denis; Bruyère, Karine; Masson, Catherine; Drazétic, Pascal
2014-03-21
The present study aims at providing quantitative data for the personalisation of geometrical and mechanical characteristics of the adult cranial bone to be applied to head FE models. A set of 351 cranial bone samples, harvested from 21 human skulls, were submitted to three-point bending tests at 10 mm/min. For each of them, an apparent elastic modulus was calculated using the beam's theory and a density-dependant beam inertia. Thicknesses, apparent densities and percentage of ash weight were also measured. Distributions of characteristics among the different skull bones show their symmetry and their significant differences between skull areas. A data analysis was performed to analyse potential relationship between thicknesses, densities and the apparent elastic modulus. A specific regression was pointed out to estimate apparent elastic modulus from the product of thickness by apparent density. These results offer quantitative tools in view of personalising head FE models and thus improve definition of local injury criteria for this body part.
Roux, A; Laporte, S; Lecompte, J; Gras, L-L; Iordanoff, I
2016-01-25
The muscle-tendon complex (MTC) is a multi-scale, anisotropic, non-homogeneous structure. It is composed of fascicles, gathered together in a conjunctive aponeurosis. Fibers are oriented into the MTC with a pennation angle. Many MTC models use the Finite Element Method (FEM) to simulate the behavior of the MTC as a hyper-viscoelastic material. The Discrete Element Method (DEM) could be adapted to model fibrous materials, such as the MTC. DEM could capture the complex behavior of a material with a simple discretization scheme and help in understanding the influence of the orientation of fibers on the MTC׳s behavior. The aims of this study were to model the MTC in DEM at the macroscopic scale and to obtain the force/displacement curve during a non-destructive passive tensile test. Another aim was to highlight the influence of the geometrical parameters of the MTC on the global mechanical behavior. A geometrical construction of the MTC was done using discrete element linked by springs. Young׳s modulus values of the MTC׳s components were retrieved from the literature to model the microscopic stiffness of each spring. Alignment and re-orientation of all of the muscle׳s fibers with the tensile axis were observed numerically. The hyper-elastic behavior of the MTC was pointed out. The structure׳s effects, added to the geometrical parameters, highlight the MTC׳s mechanical behavior. It is also highlighted by the heterogeneity of the strain of the MTC׳s components. DEM seems to be a promising method to model the hyper-elastic macroscopic behavior of the MTC with simple elastic microscopic elements. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Chuan Wang
2013-01-01
Full Text Available In order to improve the efficiency of stainless steel stamping multistage pump, quadratic regression orthogonal test, hydraulic design, and computational fluid dynamics (CFD are used to analyze the effect of pump geometric parameters. Sixteen impellers are designed based on the quadratic regression orthogonal test, which have three factors including impeller outlet slope, impeller blade outlet stagger angle, and impeller blade outlet width. Through quadratic regression equation, the function relationship between efficiency values and three factors is established. The optimal combination of geometric parameters is found through the analysis of the regression equation. To further study the influence of blade thickness on the performance of multistage pump, numerical simulations of multistage pump with different blade thicknesses are carried out. The influence law of blade thickness on pump performance is built from the external characteristics and internal flow field. In conclusion, with the increase of blade thickness, the best efficiency point of the pump shifts to the small flow rate direction, and the vortex regions inside the pump at rated flow gradually increase, which is the main reason that pump efficiency decreases along with the increase of the blade thickness at rated flow.
Oshkour, Azim Ataollahi; Talebi, Hossein; Seyed Shirazi, Seyed Farid; Yau, Yat Huang; Tarlochan, Faris; Abu Osman, Noor Azuan
2015-02-01
This study aimed to assess the performance of different longitudinal functionally graded femoral prostheses. This study was also designed to develop an appropriate prosthetic geometric design for longitudinal functionally graded materials. Three-dimensional models of the femur and prostheses were developed and analyzed. The elastic modulus of these prostheses in the sagittal plane was adjusted along a gradient direction from the distal end to the proximal end. Furthermore, these prostheses were composed of titanium alloy and hydroxyapatite. Results revealed that strain energy, interface stress, and developed stress in the femoral prosthesis and the bone were influenced by prosthetic geometry and gradient index. In all of the prostheses with different geometries, strain energy increased as gradient index increased. Interface stress and developed stress decreased. The minimum principal stress and the maximum principal stress of the bone slightly increased as gradient index increased. Hence, the combination of the femoral prosthetic geometry and functionally graded materials can be employed to decrease stress shielding. Such a combination can also be utilized to achieve equilibrium in terms of the stress applied on the implanted femur constituents; thus, the lifespan of total hip replacement can be prolonged.
DEFF Research Database (Denmark)
Putzer, Michael; Rasmussen, John; Penzkofer, Rainer;
the model according to measurements of the vertebral body height, disc height and the curvature of the spine from X-rays. Han, K.-S., Rohlmann, A., Zander, T., Taylor, W. R., 2012. Lumbar spinal loads vary with body height and weight. Medical Engineering & Physics 35, 969–977. Niemeyer, F., Wilke, H...... of the facet joints and the curvature of the lumbar spine have been varied. Figure 1 depicts the used musculoskeletal model in the flexed posture and a lumbar vertebra labeled with all relevant linear dimensions except the disc height. Additionally, all combinations of the three parameters vertebral body...... height (between 6% and 13%), vertebral body depth (up to 8%) and the curvature of the lumbar spine (up to 7%). Combinations of parameters added the results of the particular single parameter simulations with only a slight amplification. The findings for vertebral body height and disc height...
Energy Technology Data Exchange (ETDEWEB)
Jeon, Sung Woong [Dept. of Robotics Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu (Korea, Republic of); Kim, Cheol; Kim, Chung Hwan [Chungnam National University, Daejeon (Korea, Republic of)
2016-12-15
The printability of patterns for printed electronic devices determines the performance, yield rate, and reliability of the devices; therefore, it should be assessed quantitatively. In this paper, parameters for printability assessment of printed patterns for width, pinholes, and edge waviness are suggested. For quantitative printability assessment, printability grades for each parameter are proposed according to the parameter values. As examples of printability assessment, printed line patterns and mesh patterns obtained using roll-to-roll gravure printing are used. Both single-line patterns and mesh patterns show different levels of printability, even in samples obtained using the same printing equipment and conditions. Therefore, for reliable assessment, it is necessary to assess the printability of the patterns by enlarging the sampling area and increasing the number of samples. We can predict the performance of printed electronic devices by assessing the printability of the patterns that constitute them.
Hunter, A.J.; Drinkwater, B.W.; Wilcox, P.D.
2011-01-01
Ultrasonic array images are adversely affected by errors in the assumed or measured imaging parameters. For non-destructive testing and evaluation, this can result in reduced defect detection and characterization performance. In this paper, an autofocus algorithm is presented for estimating and corr
Comments on Different techniques for finding best-fit parameters
Energy Technology Data Exchange (ETDEWEB)
Fenimore, Edward E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Triplett, Laurie A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2014-07-01
A common data analysis problem is to find best-fit parameters through chi-square minimization. Levenberg-Marquardt is an often used system that depends on gradients and converges when successive iterations do not change chi-square more than a specified amount. We point out in cases where the sought-after parameter weakly affects the fit and cases where the overall scale factor is a parameter, that a Golden Search technique can often do better. The Golden Search converges when the best-fit point is within a specified range and that range can be made arbitrarily small. It does not depend on the value of chi-square.
Geometric technique for the kinematic modeling of a 5 DOF redundant manipulator
CSIR Research Space (South Africa)
Makondo, N
2012-11-01
Full Text Available to the problem and determines efficiently the relationship between the joints and the end-effector without iterative process. Using a geometric method, if a solution exists, we provide all feasible solutions to the IK problem and from these solutions an optimal...
Cubic spline approximation techniques for parameter estimation in distributed systems
Banks, H. T.; Crowley, J. M.; Kunisch, K.
1983-01-01
Approximation schemes employing cubic splines in the context of a linear semigroup framework are developed for both parabolic and hyperbolic second-order partial differential equation parameter estimation problems. Convergence results are established for problems with linear and nonlinear systems, and a summary of numerical experiments with the techniques proposed is given.
Study of automatic designing of line heating technique parameters
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Based on experimental data of line heating, the methods of vector mapping, plane projection, and coordinate converting are presented to establish the spectra for line heating distortion discipline which shows the relationship between process parameters and distortion parameters of line heating. Back-propagation network (BP-net) is used to modify the spectra.Mathematical models for optimizing line heating techniques parameters, which include two-objective functions,are constructed. To convert the multi-objective optimization into a single-objective one, the method of changing weight coefficient is used, and then the individual fitness function is built up. Taking the number of heating lines, distance between the heating lines' border (line space), and shrink quantity of lines as three restrictive conditions,a hierarchy genetic algorithm (HGA) code is established by making use of information provided by the spectra, in which inner coding and outer coding adopt different heredity arithmetic operators in inherent operating. The numerical example shows that the spectra for line heating distortion discipline presented here can provide accurate information required by techniques parameter prediction of line heating process and the technique parameter optimization method based on HGA provided here can obtain good results for hull plate.
Parameter Estimation Technique of Nonlinear Prosthetic Hand System
Directory of Open Access Journals (Sweden)
M.H.Jali
2016-10-01
Full Text Available This paper illustrated the parameter estimation technique of motorized prosthetic hand system. Prosthetic hands have become importance device to help amputee to gain a normal functional hand. By integrating various types of actuators such as DC motor, hydraulic and pneumatic as well as mechanical part, a highly useful and functional prosthetic device can be produced. One of the first steps to develop a prosthetic device is to design a control system. Mathematical modeling is derived to ease the control design process later on. This paper explained the parameter estimation technique of a nonlinear dynamic modeling of the system using Lagrangian equation. The model of the system is derived by considering the energies of the finger when it is actuated by the DC motor. The parameter estimation technique is implemented using Simulink Design Optimization toolbox in MATLAB. All the parameters are optimized until it achieves a satisfactory output response. The results show that the output response of the system with parameter estimation value produces a better response compare to the default value
Parameter tuning of PVD process based on artificial intelligence technique
Norlina, M. S.; Diyana, M. S. Nor; Mazidah, P.; Rusop, M.
2016-07-01
In this study, an artificial intelligence technique is proposed to be implemented in the parameter tuning of a PVD process. Due to its previous adaptation in similar optimization problems, genetic algorithm (GA) is selected to optimize the parameter tuning of the RF magnetron sputtering process. The most optimized parameter combination obtained from GA's optimization result is expected to produce the desirable zinc oxide (ZnO) thin film from the sputtering process. The parameters involved in this study were RF power, deposition time and substrate temperature. The algorithm was tested to optimize the 25 datasets of parameter combinations. The results from the computational experiment were then compared with the actual result from the laboratory experiment. Based on the comparison, GA had shown that the algorithm was reliable to optimize the parameter combination before the parameter tuning could be done to the RF magnetron sputtering machine. In order to verify the result of GA, the algorithm was also been compared to other well known optimization algorithms, which were, particle swarm optimization (PSO) and gravitational search algorithm (GSA). The results had shown that GA was reliable in solving this RF magnetron sputtering process parameter tuning problem. GA had shown better accuracy in the optimization based on the fitness evaluation.
Influence of geometrical parameters on the flexural rigidity of the LHC dipole cold mass assembly
Bajko, M; Pardons, A
2002-01-01
In order to predict the mechanical behavior of the LHC dipole cold mass in situations such as handling, transport and cool down, a number of important structural parameters are required. The dipole's flexural rigidity determines entirely the mechanical elastic behavior of the cold mass. Therefore, models of a bent cold mass were created to calculate its rigidity. This paper presents a simplified parametric finite element model, created to study the deflection of the cold mass in different situations and supporting conditions. The sensitivity of the models to the supporting conditions is computed. To provide the finite element and the analytical models with input, the deflection of the cold mass under discrete loads in normal condition and then 90-degrees rotated were measured with a laser tracker. By comparing models with measurements, the vertical and transversal rigidity of the cold mass assembly are determined. Additionally, the paper reports on the plastic behavior of the cold mass assembly in the range o...
Influence of geometrical parameters on the linear stability of a Bénard-Marangoni problem
Hoyas, S.; Fajardo, P.; Pérez-Quiles, M. J.
2016-04-01
A linear stability analysis of a thin liquid film flowing over a plate is performed. The analysis is performed in an annular domain when momentum diffusivity and thermal diffusivity are comparable (relatively low Prandtl number, Pr =1.2 ). The influence of the aspect ratio (Γ ) and gravity, through the Bond number (Bo ), in the linear stability of the flow are analyzed together. Two different regions in the Γ -Bo plane have been identified. In the first one the basic state presents a linear regime (in which the temperature gradient does not change sign with r ). In the second one, the flow presents a nonlinear regime, also called return flow. A great diversity of bifurcations have been found just by changing the domain depth d . The results obtained in this work are in agreement with some reported experiments, and give a deeper insight into the effect of physical parameters on bifurcations.
Performance of HCCI Diesel Engine under the Influence of Various Working and Geometrical Parameters
Directory of Open Access Journals (Sweden)
T. Karthikeya Sharma
2012-06-01
Full Text Available Homogenous-charge-compression-ignition (HCCI engines have the benefit of high efficiency with low emissions of NO and particulates. These benefits are due to the autoignition process of the dilute mixture of fuel and air during compression. Homogenous Compression ignition (HCCI is a combustion concept, which is a hybrid between Otto engine and Diesel engine. The other emissions like HC and CO are high but can be after treated by a catalyst. This paper reviews the Characteristics of HCCI combustion in direct injection diesel engines under various governing factors in HCCI operations such as injection timing, injection pressure, piston bowl geometry, compression ratio, intake charge temperature, exhaust gas recirculation (EGR and supercharging or turbo charging are discussed in this review. The effects of design and operating parameters on HCCI diesel combustion, emissions particularly NOx and soot are reviewed.
Cappetti, N; Naddeo, A; Naddeo, F; Solitro, G F
2016-09-01
The aim of this work is to show a quick and simple procedure able to identify the geometrical parameters of the intervertebral disc that strongly affect the behavior of the FEM model. First, we allocated a selection criterion for the minimum number of geometrical parameters that describe, with a good degree of approximation, a healthy human vertebra. Next, we carried out a sensitivity analysis using the 'Taguchi orthogonal array' to arrive at a quick identification of the parameters that strongly affect the behavior of the Fem model.
Physical and Geometrical Parameters of CVBS XI: COU1511 (HIP12552)
Al-Wardat, Mashhoor A; Yusuf, Nihad A; Khasawneh, Awni M; Masda, Suhail G
2016-01-01
Model atmospheres of the close visual binary star COU1511 (HIP12552) are constructed using grids of Kuruz's blanketed models to build the individual synthetic SEDs for both components. These synthetic SED's are combined together for the entire system and compared with the observational one following Al-Wardat's complex method for analyzing close visual binary stars. The entire observational spectral energy distribution (SED) of the system is used as a reference for comparison between synthetic SED and the observed one. The parameters of both components are derived as: $T_{\\rm eff}^{a} =6180\\pm50 $\\,K, $T_{\\rm eff}^{b} =5865\\pm70$\\,K, log $g_{a}=4.35\\pm0.12$, log $g_{b}=4.45\\pm0.14$, $R_{a}=1.262\\pm0.08R_\\odot$, $R_{b}=1.006\\pm0.07R_\\odot$, $L_a=2.09\\pm0.10 L_\\odot$, $L_b=1.08\\pm0.12L_\\odot$, with spectral types F8 and G1 for both components (a,b) respectively, and age of $3.0\\pm 0.9$ Gy. A modified orbit of the system is built and the masses of the two components are calculated as $M_a=1.17\\pm0.11M_\\odot$, $M...
Piretzidis, Dimitrios; Sideris, Michael G.
2016-04-01
This study investigates the possibilities of local hydrology signal extraction using GRACE data and conventional filtering techniques. The impact of the basin shape has also been studied in order to derive empirical rules for tuning the GRACE filter parameters. GRACE CSR Release 05 monthly solutions were used from April 2002 to August 2015 (161 monthly solutions in total). SLR data were also used to replace the GRACE C2,0 coefficient, and a de-correlation filter with optimal parameters for CSR Release 05 data was applied to attenuate the correlation errors of monthly mass differences. For basins located at higher latitudes, the effect of Glacial Isostatic Adjustment (GIA) was taken into account using the ICE-6G model. The study focuses on three geometric properties, i.e., the area, the convexity and the width in the longitudinal direction, of 100 basins with global distribution. Two experiments have been performed. The first one deals with the determination of the Gaussian smoothing radius that minimizes the gaussianity of GRACE equivalent water height (EWH) over the selected basins. The EWH kurtosis was selected as a metric of gaussianity. The second experiment focuses on the derivation of the Gaussian smoothing radius that minimizes the RMS difference between GRACE data and a hydrology model. The GLDAS 1.0 Noah hydrology model was chosen, which shows good agreement with GRACE data according to previous studies. Early results show that there is an apparent relation between the geometric attributes of the basins examined and the Gaussian radius derived from the two experiments. The kurtosis analysis experiment tends to underestimate the optimal Gaussian radius, which is close to 200-300 km in many cases. Empirical rules for the selection of the Gaussian radius have been also developed for sub-regional scale basins.
Abbasi, Bahman
2012-11-01
Owing to their manufacturability and reliability, capillary tubes are the most common expansion devices in household refrigerators. Therefore, investigating flow properties in the capillary tubes is of immense appeal in the said business. The models to predict pressure drop in two-phase internal flows invariably rely upon highly precise geometric information. The manner in which capillary tubes are manufactured makes them highly susceptible to geometric imprecisions, which renders geometry-based models unreliable to the point of obsoleteness. Aware of the issue, manufacturers categorize capillary tubes based on Nitrogen flow rate through them. This categorization method presents an opportunity to substitute geometric details with Nitrogen flow data as the basis for customized models. The simulation tools developed by implementation of this technique have the singular advantage of being applicable across flow regimes. Thus the error-prone process of identifying compatible correlations is eliminated. Equally importantly, compressibility and chocking effects can be incorporated in the same model. The outcome is a standalone correlation that provides accurate predictions, regardless of any particular fluid or flow regime. Thereby, exploratory investigations for capillary tube design and optimization are greatly simplified. Bahman Abbasi, Ph.D., is Lead Advanced Systems Engineer at General Electric Appliances in Louisville, KY. He conducts research projects across disciplines in the household refrigeration industry.
On N = 2 compactifications of M-theory to AdS{sub 3} using geometric algebra techniques
Energy Technology Data Exchange (ETDEWEB)
Babalic, E. M.; Coman, I. A.; Condeescu, C.; Micu, A. [IFIN-HH, Department of Theoretical Physics, 077125 Magurele (Romania); Lazaroiu, C. I. [IFIN-HH, Department of Theoretical Physics, 077125 Magurele, Romania and IBS, Center for Geometry and Physics, and POSTECH, Department of Mathematics, Pohang, Gyeongbuk 790-784 (Korea, Republic of)
2013-11-13
We investigate the most general warped compactification of eleven-dimensional supergravity on eight-dimensional manifolds to AdS{sub 3} spaces (in the presence of non-vanishing four-form flux) which preserves N = 2 supersymmetry in three dimensions. Without imposing any restrictions on the chirality of the internal part of the supersymmetry generators, we use geometric algebra techniques to study some implications of the supersymmetry constraints. In particular, we discuss the Lie bracket of certain vector fields constructed as pinor bilinears on the compactification manifold.
Measuring 3-D location and shape parameters of cylinders by a spatial encoding technique
Energy Technology Data Exchange (ETDEWEB)
Chen, Z.; Chia, T.L.; Ho, S.Y. (National Chiao Tung Univ., Hsinchu (Taiwan, Province of China). Inst. of Computer Science and Information Engineering)
1994-10-01
The authors are concerned with the problem of estimation of true cylinder radius, height, location, and orientation. The authors present mathematical models for measuring these location and shape parameters using a spatial encoding technique. A crucial step in the proposed method is to convert the estimation problem with complex curved stripe patterns to an equivalent, but simpler, estimation problem with line stripe patterns. The notions of silhouette edges and virtual plane are introduced. Various projective geometry techniques are applied to derive the cylinder location and shape parameters. The actual experiment apparatus is et up to employ the developed mathematical models to measure the cylinder geometric parameters. Description of the image-processing tasks for extracting perceived curved stripes and stripe endpoints is given. Sensitivity analysis and proper measures are taken to consider the effects of the uncertainties of stripe endpoints and silhouette edge locations on the measurement. Experiments have confirmed that their measurement method yields quite good results for different cylinders under various measurement environment conditions.
Application of geometric algebra to electromagnetic scattering the Clifford-Cauchy-Dirac technique
Seagar, Andrew
2016-01-01
This work presents the Clifford-Cauchy-Dirac (CCD) technique for solving problems involving the scattering of electromagnetic radiation from materials of all kinds. It allows anyone who is interested to master techniques that lead to simpler and more efficient solutions to problems of electromagnetic scattering than are currently in use. The technique is formulated in terms of the Cauchy kernel, single integrals, Clifford algebra and a whole-field approach. This is in contrast to many conventional techniques that are formulated in terms of Green's functions, double integrals, vector calculus and the combined field integral equation (CFIE). Whereas these conventional techniques lead to an implementation using the method of moments (MoM), the CCD technique is implemented as alternating projections onto convex sets in a Banach space. The ultimate outcome is an integral formulation that lends itself to a more direct and efficient solution than conventionally is the case, and applies without exception to all types...
Identification of System Parameters by the Random Decrement Technique
DEFF Research Database (Denmark)
Brincker, Rune; Kirkegaard, Poul Henning; Rytter, Anders
1991-01-01
The aim of this paper is to investigate and illustrate the possibilities of using correlation functions estimated by the Random Decrement Technique as a basis for parameter identification. A two-stage system identification system is used: first, the correlation functions are estimated by the Rand......-Walker equations and finally, least-square fitting of the theoretical correlation function. The results are compared to the results of fitting an Auto Regressive Moving Average (ARMA) model directly to the system output from a single-degree-of-freedom system loaded by white noise....
Chae, Eun Jung; Akcabay, Deniz Tolga; Young, Yin Lu
2013-11-01
There is an increasing interest to use innovative passive/active flexible lifting surfaces to take advantage of the fluid-structure interaction (FSI) response to improve performance or harvest energy. However, design and testing of flexible lifting surfaces are quite complicated, particularly for lightweight structures in a dense, viscous fluid. The objectives of this work are to (1) investigate the influence of varying fluid, material, and geometric parameters on the FSI response and stability boundaries, and (2) to develop generic parametric maps to facilitate the design of flexible lifting surfaces In particular, the focus is on the influence of solid-to-fluid density ratio, Reynolds number, relative stiffness ratio, and relative excitation frequency ratio on the FSI response and static/dynamic divergence and flutter stability boundaries. The results show that the governing failure mode transitions from flutter to dynamic divergence to static divergence when the solid-to-fluid added mass ratio decreases. In addition, classic linear potential theory is severely under-conservative in predicting the flutter boundary, and cannot predict the transition to dynamic divergence for cases in the low mass ratio regimes due to the strong nonlinear, viscous FSI response that develops when the fluid forces are comparable or greater than the solid forces. The Office of Naval Research (Grant no. N00014-11-1-0833); the National Research Foundation of Korea (GCRC-SOP Grant no. 2012-0004783).
Talaghat, Mohammad Reza; Jokar, Seyyed Mohammad
2017-06-01
This article offers a study on estimation of heat transfer parameters (coefficient and thermal diffusivity) using analytical solutions and experimental data for regular geometric shapes (such as infinite slab, infinite cylinder, and sphere). Analytical solutions have a broad use in experimentally determining these parameters. Here, the method of Finite Integral Transform (FIT) was used for solutions of governing differential equations. The temperature change at centerline location of regular shapes was recorded to determine both the thermal diffusivity and heat transfer coefficient. Aluminum and brass were used for testing. Experiments were performed for different conditions such as in a highly agitated water medium (T = 52 °C) and in air medium (T = 25 °C). Then, with the known slope of the temperature ratio vs. time curve and thickness of slab or radius of the cylindrical or spherical materials, thermal diffusivity value and heat transfer coefficient may be determined. According to the method presented in this study, the estimated of thermal diffusivity of aluminum and brass is 8.395 × 10-5 and 3.42 × 10-5 for a slab, 8.367 × 10-5 and 3.41 × 10-5 for a cylindrical rod and 8.385 × 10-5 and 3.40 × 10-5 m2/s for a spherical shape, respectively. The results showed there is close agreement between the values estimated here and those already published in the literature. The TAAD% is 0.42 and 0.39 for thermal diffusivity of aluminum and brass, respectively.
Institute of Scientific and Technical Information of China (English)
康盛亮
2001-01-01
Using the modified method of multiple scales, the nonlinear stability of a truncated shallow spherical shell of variable thickness with a nondeformable rigid body at the center under compound loads is investigated. When the geometrical parameter k is larger,the uniformly valid asymptotic solutions of this problem are obtained and the remainder terms are estimated.
Directory of Open Access Journals (Sweden)
Gh. Manafiazar
2010-02-01
Full Text Available This experimental study was carried out to determine the efficacy of rumen cannulation technique on some rumen metabolic parameters in buffaloes. Four healthy male River (Azari buffaloes with no previous history of gastrointestinal dysfunction were chosen. There are several surgical techniques that can be used for rumen cannulation in farm animals, including buffaloes. This procedure was performed in a modified two-stage technique. In the first stage, the dorso – lateral portion of the dorsal sac of the rumen wall was sutured to the skin incision in the left para lumbar fossa region. In the second – stage, after six days left, the exposed rumen wall area was incised and the cannula was inserted and fixed manually in the rumenal opening incision site. In order to evaluate the efficacy of rumen cannulation technique on some rumen metabolic parameters, this study was achieved with different levels of NDF, and chewing behavior and their relationship with ruminal acidity, was measured in a change over design. Two diets with 2 levels of NDF were used as treatments. First and second diets had 52 and 47 % of NDF, respectively. Animals fed ad libitum at 09:00 and 21:00. There were no significant differences between chemical composition, particles distribution, geometric mean, its standard deviation and physically effective factor (pef of diets, dry matter intake (kg/d and nutrients intake (NDF, ADF, NFC and crude protein and their digestibility. Increasing NFC reduced ruminal pH at 0.5, 1.0, 4.5, 6.0 9.0 and 10.0 h post feeding. In addition, there were not significant differences on eating time, rumination time and total chewing activity between diets. All data obtained in this study were in normal range may indicating the efficacy of this cannulation method. More investigation should be done to determine the efficacy and comparison of the other surgical rumen cannulation techniques on Azari buffaloes of Iran.
Analytical Technique of Selection of Constructive Parameters Pneumatichydraulic Springs
Directory of Open Access Journals (Sweden)
A. A. Tsipilev
2014-01-01
Full Text Available The article "Technique for Analytical Selection of Design Parameters of Pneumatichydraulic Springs concerns the ride smoothness of high-speed vehicles. Author of article Tsipilev A.A. is an assistant at chair "Multi-purpose Tracked Vehicles and Mobile Robots" of BMSTU. The article represents a synthesis of known information on the springing systems and an analysis of relation between spring design data and running gear. It describes standard units of running gear of vehicle in the context of springing systems. Classification of springing systems is considered. Modernization general policy for existing suspensions and prospects for creation of new ones are given. The article considers a design of various pneumatic-hydraulic springs to be set on domestic tracked vehicles. A developed technique allows us to have elastic characteristics of pneumatic-hydraulic springs of various types using these design data and kinematics of the running gear. The article provides recommendations to calculate characteristics of springing systems. The adequacy analysis of the given technique based on the comparison of real and rated characteristics of the existing suspension is conducted. This article can be useful to the experts dealing with springing systems of wheel and tracked vehicles.
Ghigo, A. R.; Delestre, O.; Fullana, J.-M.; Lagrée, P.-Y.
2017-02-01
The purpose of this work is to construct a simple, efficient and accurate well-balanced numerical scheme for one-dimensional (1D) blood flow in large arteries with varying geometrical and mechanical properties. As the steady states at rest are not relevant for blood flow, we construct two well-balanced hydrostatic reconstruction techniques designed to preserve low-Shapiro number steady states that may occur in large network simulations. The Shapiro number Sh = u / c is the equivalent of the Froude number for shallow water equations and the Mach number for compressible Euler equations. The first is the low-Shapiro hydrostatic reconstruction (HR-LS), which is a simple and efficient method, inspired from the hydrostatic reconstruction technique (HR). The second is the subsonic hydrostatic reconstruction (HR-S), adapted here to blood flow and designed to exactly preserve all subcritical steady states. We systematically compare HR, HR-LS and HR-S in a series of single artery and arterial network numerical tests designed to evaluate their well-balanced and wave-capturing properties. The results indicate that HR is not adapted to compute blood flow in large arteries as it is unable to capture wave reflections and transmissions when large variations of the arteries' geometrical and mechanical properties are considered. On the contrary, HR-S is exactly well-balanced and is the most accurate hydrostatic reconstruction technique. However, HR-LS is able to compute low-Shapiro number steady states as well as wave reflections and transmissions with satisfying accuracy and is simpler and computationally less expensive than HR-S. We therefore recommend using HR-LS for 1D blood flow simulations in large arterial network simulations.
Han, Taeyoung; Schubert, Frank; Hillmann, Susanne; Meyendorf, Norbert
2015-03-01
Phased array ultrasonic testing (PAUT) techniques are widely used for the non-destructive testing (NDT) of austenitic welds to find defects like cracks. However, the propagation of ultrasound waves through the austenitic material is intricate due to its inhomogeneous and anisotropic nature. Such a characteristic leads beam path distorted which causes the signal to be misinterpreted. By employing a reference block which is cutout from the mockup of which the structure is a dissimilar metal weld (DMW), a new method of PAUT named as Referencing Delay Law Technique (RDLT) is introduced. With the RDLT, full matrix capture (FMC) was used for data acquisition. To reconstruct the images, total focusing method (TFM) was used. After the focal laws were calculated, PAUT was then performed. As a result, the flaws are more precisely positioned with significantly increased signal-to-noise ratio (SNR).
New sensor and non-contact geometrical survey for the vibrating wire technique
Energy Technology Data Exchange (ETDEWEB)
Geraldes, Renan [Brazilian Synchrotron Light Laboratory (LNLS), Campinas, SP (Brazil); Junqueira Leão, Rodrigo, E-mail: rodrigo.leao@lnls.br [Brazilian Synchrotron Light Laboratory (LNLS), Campinas, SP (Brazil); Cernicchiaro, Geraldo [Brazilian Center for Research in Physics (CBPF), Rio de Janeiro, RJ (Brazil); Terenzi Neuenschwander, Regis; Citadini, James Francisco; Droher Rodrigues, Antônio Ricardo [Brazilian Synchrotron Light Laboratory (LNLS), Campinas, SP (Brazil)
2016-03-01
The tolerances for the alignment of the magnets in the girders of the next machine of the Brazilian Synchrotron Light Laboratory (LNLS), Sirius, are as small as 40 µm for translations and 0.2 mrad for rotations. Therefore, a novel approach to the well-known vibrating wire technique has been developed and tested for the precise fiducialization of magnets. The alignment bench consists of four commercial linear stages, a stretched wire, a commercial lock-in amplifier working with phase-locked loop (PLL), a coordinate measuring machine (CMM) and a vibration sensor for the wire. This novel sensor has been designed for a larger linear region of operation. For the mechanical metrology step of the fiducialization of quadrupoles an innovative technique, using the vision system of the CMM, is presented. While the work with pitch and yaw orientations is still ongoing with promising partial results, the system already presents an uncertainty level below 10 µm for translational alignment.
Directory of Open Access Journals (Sweden)
María Jesús Algar
2013-01-01
Full Text Available An efficient approach for the analysis of surface conformed reflector antennas fed arbitrarily is presented. The near field in a large number of sampling points in the aperture of the reflector is obtained applying the Geometrical Theory of Diffraction (GTD. A new technique named Master Points has been developed to reduce the complexity of the ray-tracing computations. The combination of both GTD and Master Points reduces the time requirements of this kind of analysis. To validate the new approach, several reflectors and the effects on the radiation pattern caused by shifting the feed and introducing different obstacles have been considered concerning both simple and complex geometries. The results of these analyses have been compared with the Method of Moments (MoM results.
Estimation of Secondary Meteorological Parameters Using Mining Data Techniques
Directory of Open Access Journals (Sweden)
Rosabel Zerquera Díaz
2010-10-01
Full Text Available This work develops a process of Knowledge Discovery in Databases (KDD at the Higher Polytechnic Institute José Antonio Echeverría for the group of Environmental Research in collaboration with the Center of Information Management and Energy Development (CUBAENERGÍA in order to obtain a data model to estimate the behavior of secondary weather parameters from surface data. It describes some aspects of Data Mining and its application in the meteorological environment, also selects and describes the CRISP-DM methodology and data analysis tool WEKA. Tasks used: attribute selection and regression, technique: neural network of multilayer perceptron type and algorithms: CfsSubsetEval, BestFirst and MultilayerPerceptron. Estimation models are obtained for secondary meteorological parameters: height of convective mixed layer, height of mechanical mixed layer and convective velocity scale, necessary for the study of patterns of dispersion of pollutants in Cujae's area. The results set a precedent for future research and for the continuity of this in its first stage.
Revisiting eight-manifold flux compactifications of M-theory using geometric algebra techniques
Babalic, Elena-Mirela
2013-01-01
Motivated by open problems in F-theory, we reconsider warped compactifications of M theory on 8-manifolds to AdS3 spaces in the presence of a non-trivial field strength of the M-theory 3-form, studying the most general conditions under which such backgrounds preserve N=2 supersymmetry in three dimensions. In contrast with previous studies, we allow for the most general pair of Majorana generalized Killing pinors on the internal 8-manifold, without imposing any chirality conditions on those pinors. We also show how such pinors can be lifted to the 9-dimensional metric cone over the compactification 8-manifold. We describe the translation of the generalized Killing pinor equations for such backgrounds to a system of differential and algebraic constraints on certain form-valued pinor bilinears and develop techniques through which such equations can be analyzed efficiently.
Institute of Scientific and Technical Information of China (English)
Tian Shan; Liu Yuli; Yang He
2013-01-01
Inner flange and side wrinkling often occur in rotary-draw bending process of rectangular aluminum alloy wave-guide tubes,and the distribution and magnitude of wrinkling is related to geometrical parameters of the tubes.In order to study the effects of geometrical parameters on wrinkling of rectangular wave-guide tubes,a 3D-FE model for rotary-draw bending processes of thin-walled rectangular aluminum alloy wave-guide tubes was built based on the platform of ABAQUS/Explicit,and its reliability was validated by experiments.Simulation and analysis of the influence laws of geometrical parameters on the wave heights of inner flange and side wrinkling were then carried out.The results show that inner flange wrinkling is the main wrinkling way to rectangular wave-guide tubes in rotary-draw bending processes,but side wrinkling cannot be neglected because side wrinkling is 2/3 of inner flange wrinkling when b and h are smaller.Inner flange and side wrinkling increase with increasing b and h; the influence of b on side wrinkling is larger than that of h,while both b and h affect inner flange wrinkling greatly.Inner flange and side wrinkling decrease with increasing R/h; the influence of h on inner flange and side wrinkling is larger than that of R.
Energy Technology Data Exchange (ETDEWEB)
Huff, K. D.; Bauer, T. H. (Nuclear Engineering Division)
2012-08-20
A benchmarking effort was conducted to determine the accuracy of a new analytic generic geology thermal repository model developed at LLNL relative to a more traditional, numerical, lumped parameter technique. The fast-running analytical thermal transport model assumes uniform thermal properties throughout a homogenous storage medium. Arrays of time-dependent heat sources are included geometrically as arrays of line segments and points. The solver uses a source-based linear superposition of closed form analytical functions from each contributing point or line to arrive at an estimate of the thermal evolution of a generic geologic repository. Temperature rise throughout the storage medium is computed as a linear superposition of temperature rises. It is modeled using the MathCAD mathematical engine and is parameterized to allow myriad gridded repository geometries and geologic characteristics [4]. It was anticipated that the accuracy and utility of the temperature field calculated with the LLNL analytical model would provide an accurate 'birds-eye' view in regions that are many tunnel radii away from actual storage units; i.e., at distances where tunnels and individual storage units could realistically be approximated as physical lines or points. However, geometrically explicit storage units, waste packages, tunnel walls and close-in rock are not included in the MathCAD model. The present benchmarking effort therefore focuses on the ability of the analytical model to accurately represent the close-in temperature field. Specifically, close-in temperatures computed with the LLNL MathCAD model were benchmarked against temperatures computed using geometrically-explicit lumped-parameter, repository thermal modeling technique developed over several years at ANL using the SINDAG thermal modeling code [5]. Application of this numerical modeling technique to underground storage of heat generating nuclear waste streams within the proposed YMR Site has been widely
Pascu, A. T.; Besnea, D.; Constantin, V.; Spanu, A.; Ciobanu, R.
2016-08-01
The paper presents the usual methods and means for geometrical evaluation and measurement for the anterior pole of the eyeball applied in studies conducted on real patients. The results were centralized, evaluated and presented in a summary in the paper. The purpose of the studies is to determine the range of dimensional values of the anterior pole of the human eyeball for the parameterization of the devices and checking tools when manufacturing the contact lenses.
Spray drying technique. I: Hardware and process parameters.
Cal, Krzysztof; Sollohub, Krzysztof
2010-02-01
Spray drying is a transformation of feed from a fluid state into a dried particulate form by spraying the feed into a hot drying medium. The main aim of drying by this method in pharmaceutical technology is to obtain dry particles with desired properties. This review presents the hardware and process parameters that affect the properties of the dried product. The atomization devices, drying chambers, air-droplet contact systems, the collection of dried product, auxiliary devices, the conduct of the spray drying process, and the significance of the individual parameters in the drying process, as well as the obtained product, are described and discussed.
Li, Xiying; Mao, Liqun; Ma, Xuehu
2013-01-29
Textured silicon surfaces decorated by square arrays of pillars with adjustable pitch were fabricated. The wetting behavior, especially for direction-dependent water contact angles on textured silicon surfaces after silanization, was investigated by incorporating the contact line fraction into a modified Wenzel model. Also, the effect of geometrical parameters on the anisotropic wetting behavior of water was examined with respect to water droplet impact on the textured surface. Moreover, the maximum spreading factor was studied theoretically in terms of energy conservation, allowing for surface topography and viscous friction of the liquid flowing among the arrays of the posts. Theoretical models were found to be in good agreement with experimental data.
Image Techniques for Identifying Sea-Ice Parameters
Directory of Open Access Journals (Sweden)
Qin Zhang
2014-10-01
Full Text Available The estimation of ice forces are critical to Dynamic Positioning (DP operations in Arctic waters. Ice conditions are important for the analysis of ice-structure interaction in an ice field. To monitor sea-ice conditions, cameras are used as field observation sensors on mobile sensor platforms in Arctic. Various image processing techniques, such as Otsu thresholding, k-means clustering, distance transform, Gradient Vector Flow (GVF Snake, mathematical morphology, are then applied to obtain ice concentration, ice types, and floe size distribution from sea-ice images to ensure safe operations of structures in ice covered regions. Those techniques yield acceptable results, and their effectiveness are demonstrated in case studies.
Jargus, Jan; Nedoma, Jan; Fajkus, Marcel; Novak, Martin; Bednarek, Lukas; Vasinek, Vladimir
2017-05-01
White light is produced by a suitable combination of spectral components RGB (colors) or through exposure excitation of blue light (the blue component of light). This blue part of the light is partly and suitably transformed by luminophore so that the resulting emitted spectrum corresponded to the spectral characteristics of white light with a given correlated color temperature (CCT). This paper deals with the measurement of optical properties of a mixture polydimethylsiloxane (PDMS) and luminophore, which is irradiated by the blue LED (Light-Emitting Diode) to obtain the white color of light. The subject of the investigation is the dependence of CCT on the concentration of the luminophore in a mixture of PDMS and different geometrical parameters of the samples. There are many kinds of PDMS and luminophore. We used PDMS Sylgard 184 and luminophore-labeled U2. More accurately Yttrium Aluminium Oxide: Cerium Y3Al5O12: Ce. From the analyzed data, we determined, which mutual combinations of concentration of the mixture of luminophore and PDMS together with the geometric parameters of the samples of the special optical fibers are suitable for illumination, while we get the desired CCT.
Kocijan, Roland; Muschitz, Christian; Fratzl-Zelman, Nadja; Haschka, Judith; Dimai, Hans-Peter; Trubrich, Angela; Bittighofer, Christina; Resch, Heinrich
2013-02-01
Osteogenesis imperfecta (OI) is an inherited disorder characterized by increased bone fragility with recurrent fractures that leads to skeletal deformities in severe cases. Consequently, in most OI patients, the hip is the only reliable measuring site for estimating future fracture risk. The aim of the study was to assess the applicability of hip structure analysis (HSA) by DXA in adult patients with osteogenesis imperfecta. We evaluated bone mineral density (BMD) and hip structure analysis (HSA) by DXA, including cross-sectional area (CSA), cross-sectional moment of inertia (CSMI) and femoral strength index (FSI) in 30 adult patients with different types of OI and 30 age-matched healthy controls (CO). The OI total group (OI-tot) was divided into two subgroups: the mild OI I group (OI-I) and the more severe OI III and IV group (OI-III-IV). The mean neck BMD of OI-I and OI-III-IV were significantly lower compared to CO (-15.9 %, p osteogenesis imperfecta and controls. BMD measurement in osteogenesis imperfecta patients is very critical. The combination of BMD and geometric structural measurements at the hip in osteogenesis imperfecta patients may represent an additional helpful means in estimating bone strength and fracture risk.
Mandrosov, V. I.
2008-01-01
The possibility of using Young-Michelson and Brown-Twiss interferometers for measuring the angular dimensions and parameters of the surface shape of remote passively scattering and self-luminous nonplanar rough objects by optical radiation propagating from them is substantiated. The analysis is base
[The research advance of measuring techniques on corneoscleral constitutive parameters].
Bao, Fangjun; Deng, Manli; Wang, Qinmei
2015-11-01
The occurrence and development of myopia and keratoconus is closely related to the changes of scleral and corneal biomechanical properties. The accurate measurement of biomechanical properties for corneoscleral tissure is very important on diagnosis of eye diseases, improvement of ocular operation, ocular biological parameter measurement and invention of ophthalmic instrument. Corneoscleral tissue, composed of bundles of compact and staggered collagen fiber and extracellular matrix, constitute the outer surface of the eyeball. The inhomogeneous distribution of the diameter, gap and amount of collagen fiber, makes its biomechanical characteristics really complex, characterized by nonlinear, viscoelastic, anisotropic, regional variation and age-related variation and etc. With the development of medical diagnostic technology, the importance of the ocular biomechanical property measurement is increasingly recognized. Nevertheless, measuring technology on ocular biomechanics properties are still not well understood by the majority of ophthalmologists. In order to facilitate the researchers to select a suitable measuring platform and method, the development of international corneoscleral biomechanical propertiy measuring technology was reviewed in this article.
Worldwide Injection Technique Questionnaire Study: Population Parameters and Injection Practices.
Frid, Anders H; Hirsch, Laurence J; Menchior, Astrid R; Morel, Didier R; Strauss, Kenneth W
2016-09-01
From February 1, 2014, through June 30, 2015, 13,289 insulin-injecting patients from 423 centers in 42 countries took part in one of the largest surveys ever performed in diabetes. The goal was to assess patient characteristics, as well as historical and practical aspects of their injection technique. Results show that 4- and 8-mm needle lengths are each used by nearly 30% of patients and 5- and 6-mm needles each by approximately 20%. Higher consumption of insulin (as measured by total daily dose) is associated with having lipohypertrophy (LH), injecting into LH, leakage from the injection site, and failing to reconstitute cloudy insulin. Glycated hemoglobin values are, on average, 0.5% higher in patients with LH and are significantly higher with incorrect rotation of sites and with needle reuse. Glycated hemoglobin values are lower in patients who distribute their injections over larger injection areas and whose sites are inspected routinely. The frequencies of unexpected hypoglycemia and glucose variability are significantly higher in those with LH, those injecting into LH, those who incorrectly rotate sites, and those who reuse needles. Needles associated with diabetes treatment are the most commonly used medical sharps in the world. However, correct disposal of sharps after use is critically suboptimal. Many used sharps end up in public trash and constitute a major accidental needlestick risk. Use of these data should stimulate renewed interest in and commitment to optimizing injection practices in patients with diabetes.
Rainbow technique for multi-parameter measurement of absorbing cylinder
Institute of Scientific and Technical Information of China (English)
Feihu Song; Chuanlong Xu; Shimin Wang
2013-01-01
Rainbow refractometry is widely used to measure the radius and real part of refractive index of a cylinder.However,studies on the detection of imaginary part of the refractive index with rainbow technique were scarce.This paper presents a new method for simultaneously measuring the radius,real and imaginary part of the refractive index of a cylinder,on the basis of the Airy theory and the Bouguer theory.The rainbows produced by the illuminated cylinder at a capillary exit are captured by a CCD camera in a labscale system,and then processed by the proposed method.Experimental results showed that the radius,real and imaginary part of the refractive index can be accurately determined when the SNR (signal to noise ratio) of the ripple structure is sufficiently high.However,the SNR of the ripple structure gradually decreases with decreasing scattering intensity of the cylinder,leading to larger measurement errors of the radius and real part of the refractive index.The relative error of the imaginary part of the refractive index derived from the measurement errors of the radius and real part of the refractive index,is less than 3.4％.
Energy Technology Data Exchange (ETDEWEB)
Rocha, Wilson Roberto Dejato da
2005-07-01
In this work, the gamma rays transmission and X-rays microtomography techniques are used for the evaluation of the porosity and the pore size distribution of SiC ceramic foams. It was also accomplished the three-dimensional images after the determination of samples geometric parameters. The geometric parameters were obtained by two-dimensional images analyses, generated by a Microfocus system, with a CCD camera, an images intensifier, a X-rays tube and an automatic system for rotation of the sample. The spatial resolution of the images was about 32 {mu}m. In the gamma rays transmission methodology, a Nal(Tl) scintillation detector, an {sup 241}Am (59.53 keV, 100 mCi) radioactive source and an automatic X-Z micrometric table was used. The analyzed samples had pores density of 30, 45, 60, 80 and 100 ppi (pores per inch). The gamma rays transmission technique was accurate to supply the porosity of the samples, which ranged about 90% and was in agreement with the values supplied by manufacturer of the foams. The 30 and 45 ppi samples analyzed by X-rays microtomography showed porosity results that agree with the average porosity supplied by the manufacturer. In other hand, the 60, 80 and 100 ppi samples systematically showed average porosity about 4%, lower than the average of the manufacturer. The pore size distributions found through the software IMAGO show the presence of smaller pores than those nominated by the manufacturer. The 30 ppi samples had voids inside the solid material of the ceramic foams structure. Gaussian truncated method, used in the three-dimensional reconstruction, was not able to take into the account the voids inside the solid matrix. (author)
Pirc, Gordana; Stare, Jernej; Mavri, Janez; Vianello, Robert
2014-01-01
Chemometric statistical approaches involving multiple linear regression (MLR) and principal compo-nent analysis (PCA) were employed on a set of 42 distinct snapshot structures of the physiological histamine monocation in aqueous solution along the Car-Parrinello molecular dynamics trajectory, in order to obtain a better insight into the relationship between the geometry parameters of the system and the resulting νNH stretching frequencies. A simple 2D linear regression of νNH with Namino•••Ow...
Canbulut, Fazıl
In this paper, the characteristics of disk-type hydrostatic thrust bearings supporting concentric loads; simulating the major bearing/seal parts of axial piston pumps and motors were investigated. An experimental setup was designed to determine the performance of slippers, which are capable of increasing the efficiency of axial piston pumps and motors, for different conditions. The working parameters and the slipper geometry causing the minimum frictional power loss and leakage oil loss were determined. Since slippers affect the performance of the system considerably, the effects of surface roughnesses on lubrication were studied in slippers with varying hydrostatic bearing areas and surface roughness. The results of the study suggest that the frictional power loss and leakage oil loss were caused by the surface roughness, the relative velocity, the size of the hydrostatic bearing area, supply pressure and capillary tube diameter.
Institute of Scientific and Technical Information of China (English)
Hui JIANG; Shu-feng LEI; Su-mei XIAO; Yuan CHEN; Xiao SUN; Fang YANG; Li-ming LI; Shun WU; Hong-wen DENC
2007-01-01
Aim: To simultaneously investigate the contribution of the alpha 1 chain of col-lagen type 1 (COL1A1) and alpha2-HS-glycoprotein (AHSG) genes to the varia-tion of bone geometric parameters in both Caucasians and Chinese. Methods: Six hundred and five Caucasian individuals from 157 nuclear families and 1228 Chi-nese subjects from 400 nuclear families were genotyped at the AHSG-Sacl, COL1A1-PCOL2 and Sp1 polymorphisms using polymerase chain reaction (PCR)-restric-tion fragment length polymorphism (RFLP). 5 FN bone geometric parameters were calculated based on bone mineral density and bone area of femoral neck (FN)measured by dual energy X-ray absorptiometry. Population stratification, total family association, within-family association, and linkage tests were performed by the quantitative transmission disequilibrium test program. Results: The t-test showed the significant differences of all bone geometric phenotypes (except ED)between Caucasians and Chinese in the offspring using both unadjusted and adjusted (by age, height, weight, and gender) data. In Caucasians, we found significant within-family association results between the COL1A1-Sp1 polymor-phism (rs1800012) and cross sectional area (CSA), cortical thickness (CT),endocortical diameter (ED), buckling ratio (BR) (P=0.018, 0.002, 0.023, and 0.001,respectively); the COL1A1-Sp1 polymorphism also detected significant linkage with BR (P=0.039). In the population of China, the within-family associations between the COL1A1-PCOL2 polymorphism (rs1107946) and CT, BR were signifi-cant (P=0.012 and 0.008, respectively). Furthermore, evidence of linkage were observed between the AHSG-SacI polymorphism (rs4918) and CT, BR (P--0.042 and 0.014, respectively) in Caucasians, but not in Chinese. Conclusion: Our results suggest that the COL1A1 gene may have significantly association with bone geometry in both Caucasians and Chinese, and the AHSG gene may be linked to bone geometry in Caucasians, but not in Chinese. This study
半封闭螺旋输送机运动量及几何参数确定%Semi-enclosed Screw Conveyor Exercise and Geometric Parameters
Institute of Scientific and Technical Information of China (English)
李新; 薛风
2013-01-01
Based on the closed spiral conveyor within a single material as the research object, this paper carries on the analysis, obtains the granular material parameter design criterion and the formula for calculation and checking, providing the way for selecting and determining semi-enclosed screw conveyor operating parameters and geometric parameters, to be conduce to semi hermetic screw conveyor design and application.% 通过对半封闭螺旋输送机内单颗物料为研究对象进行分析，得出了输送散体物料过程中主要参数设计准则及其计算和校验公式，为半封闭螺旋输送机的工作参数和几何参数的选择和确定提供了方法，有助于半封闭螺旋输送机的设计和应用。
Morris, A. Terry
1999-01-01
This paper examines various sources of error in MIT's improved top oil temperature rise over ambient temperature model and estimation process. The sources of error are the current parameter estimation technique, quantization noise, and post-processing of the transformer data. Results from this paper will show that an output error parameter estimation technique should be selected to replace the current least squares estimation technique. The output error technique obtained accurate predictions of transformer behavior, revealed the best error covariance, obtained consistent parameter estimates, and provided for valid and sensible parameters. This paper will also show that the output error technique should be used to minimize errors attributed to post-processing (decimation) of the transformer data. Models used in this paper are validated using data from a large transformer in service.
Geometrical Bioelectrodynamics
Ivancevic, Vladimir G
2008-01-01
This paper proposes rigorous geometrical treatment of bioelectrodynamics, underpinning two fast-growing biomedical research fields: bioelectromagnetism, which deals with the ability of life to produce its own electromagnetism, and bioelectromagnetics, which deals with the effect on life from external electromagnetism. Keywords: Bioelectrodynamics, exterior geometrical machinery, Dirac-Feynman quantum electrodynamics, functional electrical stimulation
Directory of Open Access Journals (Sweden)
Filipović Ivan
2011-01-01
Full Text Available The main role in air/fuel mixture formation at the IC diesel engines has the energy introduced by fuel into the IC engine that is the characteristics of spraying fuel into the combustion chamber. The characteristic can be defined by the spray length, the spray cone angle, the physical and the chemical structure of fuel spray by different sections. Having in mind very complex experimental setups for researching in this field, the mentioned characteristics are mostly analyzed by calculations. There are two methods in the literature, the first based on use of the semi-empirical expressions (correlations and the second, the calculations of spray characteristics by use of very complex mathematical methods. The second method is dominant in the modern literature. The main disadvantage of the calculation methods is a correct definition of real state at the end of the nozzle orifice (real boundary conditions. The majority of the researchers in this field use most frequently the coefficient of total losses inside the injector. This coefficient depends on injector design, as well as depends on the level of fuel energy and fuel energy transformation along the injector. Having in mind the importance of the real boundary conditions, the complex methods for calculation of the fuel spray characteristics should have the calculation of fuel flows inside the injector and the calculation of spray characteristics together. This approach is a very complex numerical problem and there are no existing computer programs with satisfactory calculation results. Analysis of spray characteristics by use of the semi-empirical expressions (correlations is presented in this paper. The special attention is dedicated to the analysis of the constant in the semi-empirical expressions and influence parameters on this constant. Also, the method for definition of realistic boundary condition at the end of the nozzle orifice is presented in the paper. By use of this method completely
Helicopter parameter extraction using joint Time-Frequency and Tomographic Techniques
CSIR Research Space (South Africa)
Cilliers, A
2008-09-01
Full Text Available A technique based on time-frequency and tomographic analysis to extract helicopter blade parameters for the purposes of radar non-cooperative target recognition (NCTR) is investigated. The proposed algorithm shows that (under certain conditions...
Design of the image detection system for general parts geometric parameters%通用零件几何参数图像检测系统设计
Institute of Scientific and Technical Information of China (English)
张建; 温坚; 林菁
2009-01-01
Gave image detection system for general parts geometric parameters,the optical lens,industrial digital camera and micro-computer constitute the basic detection system;designed to test preparation,test system to adjust,image acquisition,etreatment,boundary identification,and system parameters to strike a job detect calibration process;described the detection aspect of the role and application of the key questions;designed detect application software;established a detection system,comparison test for typical parts.Gave the detection system is the best and practical.%为实现通用零件几何参数图像检测,采用光学镜头、工业数字摄像机和微型计算机构成基本检测系统,包括测试准备、测试系统调整、图像获取、预处理、边界确定、参数求取和系统标定等检测工作环节.阐述各检测环节的作用和应用中的关键问题、检测应用软件设计.通过所构建的检测系统,对典型零件进行对比测试表明,给出的通用零件几何参数图像检测系统是实用的.
A Comparison of Estimation Techniques for the Three Parameter Pareto Distribution
1985-12-01
1897 Vilfredo Pareto (1848-1923), an Italian-born Swiss professor of economics, formulated an empirical law which bears his name (16:233). Pareto’s Law...DTIC00• _ZLECTE! CD S A COMPARISON OF ESTIMATION TECHNIQUES FOR THICTHE REE PARAMETER PARETO DISTRIBUTION THESIS "Dennis J. Charek Major, USAF AFIT...TECHNIQUES FOR THE THREE PARAMETER PARETO DISTRIBUTION THESIS Dennis J. Charek Major, USAF AFIT/GSO/MA/8SD-3 Approved for public release; distribution
Automatic parameter extraction technique for gate leakage current modeling in double gate MOSFET
Darbandy, Ghader; Gneiting, Thomas; Alius, Heidrun; Alvarado, Joaquín; Cerdeira, Antonio; Iñiguez, Benjamin
2013-11-01
Direct Tunneling (DT) and Trap Assisted Tunneling (TAT) gate leakage current parameters have been extracted and verified considering automatic parameter extraction approach. The industry standard package IC-CAP is used to extract our leakage current model parameters. The model is coded in Verilog-A and the comparison between the model and measured data allows to obtain the model parameter values and parameters correlations/relations. The model and parameter extraction techniques have been used to study the impact of parameters in the gate leakage current based on the extracted parameter values. It is shown that the gate leakage current depends on the interfacial barrier height more strongly than the barrier height of the dielectric layer. There is almost the same scenario with respect to the carrier effective masses into the interfacial layer and the dielectric layer. The comparison between the simulated results and available measured gate leakage current transistor characteristics of Trigate MOSFETs shows good agreement.
Measurement of Device Parameters Using Image Recovery Techniques in Large-Scale IC Devices
Scheick, Leif; Edmonds, Larry
2004-01-01
Devices that respond to radiation on a cell level will produce histograms showing the relative frequency of cell damage as a function of damage. The measured distribution is the convolution of distributions from radiation responses, measurement noise, and manufacturing parameters. A method of extracting device characteristics and parameters from measured distributions via mathematical and image subtraction techniques is described.
Geometric diffusion of quantum trajectories.
Yang, Fan; Liu, Ren-Bao
2015-07-16
A quantum object can acquire a geometric phase (such as Berry phases and Aharonov-Bohm phases) when evolving along a path in a parameter space with non-trivial gauge structures. Inherent to quantum evolutions of wavepackets, quantum diffusion occurs along quantum trajectories. Here we show that quantum diffusion can also be geometric as characterized by the imaginary part of a geometric phase. The geometric quantum diffusion results from interference between different instantaneous eigenstate pathways which have different geometric phases during the adiabatic evolution. As a specific example, we study the quantum trajectories of optically excited electron-hole pairs in time-reversal symmetric insulators, driven by an elliptically polarized terahertz field. The imaginary geometric phase manifests itself as elliptical polarization in the terahertz sideband generation. The geometric quantum diffusion adds a new dimension to geometric phases and may have applications in many fields of physics, e.g., transport in topological insulators and novel electro-optical effects.
Minimal-Learning-Parameter Technique Based Adaptive Neural Sliding Mode Control of MEMS Gyroscope
Directory of Open Access Journals (Sweden)
Bin Xu
2017-01-01
Full Text Available This paper investigates an adaptive neural sliding mode controller for MEMS gyroscopes with minimal-learning-parameter technique. Considering the system uncertainty in dynamics, neural network is employed for approximation. Minimal-learning-parameter technique is constructed to decrease the number of update parameters, and in this way the computation burden is greatly reduced. Sliding mode control is designed to cancel the effect of time-varying disturbance. The closed-loop stability analysis is established via Lyapunov approach. Simulation results are presented to demonstrate the effectiveness of the method.
Directory of Open Access Journals (Sweden)
Trunev A. P.
2014-05-01
Full Text Available In this article we have investigated the solutions of Maxwell's equations, Navier-Stokes equations and the Schrödinger associated with the solutions of Einstein's equations for empty space. It is shown that in some cases the geometric instability leading to turbulence on the mechanism of alternating viscosity, which offered by N.N. Yanenko. The mechanism of generation of matter from dark energy due to the geometric turbulence in the Big Bang has been discussed
Automatic parameter extraction techniques in IC-CAP for a compact double gate MOSFET model
Darbandy, Ghader; Gneiting, Thomas; Alius, Heidrun; Alvarado, Joaquín; Cerdeira, Antonio; Iñiguez, Benjamin
2013-05-01
In this paper, automatic parameter extraction techniques of Agilent's IC-CAP modeling package are presented to extract our explicit compact model parameters. This model is developed based on a surface potential model and coded in Verilog-A. The model has been adapted to Trigate MOSFETs, includes short channel effects (SCEs) and allows accurate simulations of the device characteristics. The parameter extraction routines provide an effective way to extract the model parameters. The techniques minimize the discrepancy and error between the simulation results and the available experimental data for more accurate parameter values and reliable circuit simulation. Behavior of the second derivative of the drain current is also verified and proves to be accurate and continuous through the different operating regimes. The results show good agreement with measured transistor characteristics under different conditions and through all operating regimes.
Directory of Open Access Journals (Sweden)
F Farias
2016-09-01
Full Text Available In the oil exploitation, produced fluids are composed of oil, gas, water and sand (depending on the reservoir location. The presence of sand in flow oil leads to several industrial problems for example: erosion and accumulation in valves and pipeline. Thus, it is necessary to stop production for manual cleaning of equipments and pipes. These facts have attracted attention of academic and industrial areas, enabling the appearing of new technologies or improvement of the water/oil/sand separation process. One equipment that has been used to promote phase separation is the hydrocyclone due to high performance of separation and required low cost to installation and maintenance. In this sense, the purpose of this work is to study numerically the effect of geometric parameters (vortex finder diameter of the hydrocyclone and sand concentration on the inlet fluid separation process. A numerical solution of the governing equations was obtained by the ANSYS CFX-11 commercial code. Results of the streamlines, pressure drop and separation efficiency on the hydrocyclone are presented and analyzed. It was observed that the particles concentration and geometry affect the separation efficiency of the hydrocyclone.
Mattern, Jann Paul; Edwards, Christopher A.
2017-01-01
Parameter estimation is an important part of numerical modeling and often required when a coupled physical-biogeochemical ocean model is first deployed. However, 3-dimensional ocean model simulations are computationally expensive and models typically contain upwards of 10 parameters suitable for estimation. Hence, manual parameter tuning can be lengthy and cumbersome. Here, we present four easy to implement and flexible parameter estimation techniques and apply them to two 3-dimensional biogeochemical models of different complexities. Based on a Monte Carlo experiment, we first develop a cost function measuring the model-observation misfit based on multiple data types. The parameter estimation techniques are then applied and yield a substantial cost reduction over ∼ 100 simulations. Based on the outcome of multiple replicate experiments, they perform on average better than random, uninformed parameter search but performance declines when more than 40 parameters are estimated together. Our results emphasize the complex cost function structure for biogeochemical parameters and highlight dependencies between different parameters as well as different cost function formulations.
Directory of Open Access Journals (Sweden)
Mansur Ziaii
2017-06-01
Full Text Available Traditional methods of chromite exploration are mostly based on geophysical techniques and drilling operations. They are expensive and time-consuming. Furthermore, they suffer from several shortcomings such as lack of sufficient geophysical density contrast. In order to overcome these drawbacks, the current research work is carried out to introduce a novel, automatic and opto-geometric image analysis (OGIA technique for extracting the structural properties of chromite minerals using polished thin sections prepared from outcrops. Several images are taken from polished thick sections through a reflected-light microscope equipped with a digital camera. The images are processed in filtering and segmentation steps to extract the worthwhile information of chromite minerals. The directional density of chromite minerals, as a textural property, is studied in different inclinations, and the main trend of chromite growth is identified. Microscopic inclination of chromite veins can be generalized for exploring the macroscopic layers of chromite buried under either the surface quaternary alluvium or overburden rocks. The performance of the OGIA methodology is tested in a real case study, where several exploratory boreholes are drilled. The results obtained show that the microscopic investigation outlines through image analysis are in good agreement with the results obtained from interpretation of boreholes. The OGIA method represents a reliable map of the absence or existence of chromite ore deposits in different horizontal surfaces. Directing the exploration investigations toward more susceptible zones (potentials and preventing from wasting time and money are the major contributions of the OGIA methodology. It leads to make an optimal managerial and economical decision.
Optimization of machining techniques – A retrospective and literature review
Indian Academy of Sciences (India)
Aman Aggarwal; Hari Singh
2005-12-01
In this paper an attempt is made to review the literature on optimizing machining parameters in turning processes. Various conventional techniques employed for machining optimization include geometric programming, geometric plus linear programming, goal programming, sequential unconstrained minimizationtechnique, dynamic programming etc. The latest techniques for optimization include fuzzy logic, scatter search technique, genetic algorithm, Taguchi technique and response surface methodology.
Energy Technology Data Exchange (ETDEWEB)
Mayo, P.; Verdu Martin, G.; Rodenas Escriba, F.; Marin Peinado, B.; Camapyo Esteban Nogueira, J. M.; Diez Domingo, S.; Villaescusa Blanca, J. I.; Hernando Gonzalez, I.; Ruiz Manzano, P.; Rivas Ballarin, M. A.; Melcho Iniguez, M.; Asensio Martinez, M. I.
2013-07-01
This paper presents the application of an innovative tool developed for the detailed quality control of diagnostic equipment. We have tried to validate such a tool for verification of geometrical parameters and the evaluation of the constancy of the image quality in radiology equipment, evaluating their usefulness by various services of Radio physics and radiation protection of different hospitals. (Author)
Muniz Oliva, Waldyr
2002-01-01
Geometric Mechanics here means mechanics on a pseudo-riemannian manifold and the main goal is the study of some mechanical models and concepts, with emphasis on the intrinsic and geometric aspects arising in classical problems. The first seven chapters are written in the spirit of Newtonian Mechanics while the last two ones as well as two of the four appendices describe the foundations and some aspects of Special and General Relativity. All the material has a coordinate free presentation but, for the sake of motivation, many examples and exercises are included in order to exhibit the desirable flavor of physical applications.
Design of U-Geometry Parameters Using Statistical Analysis Techniques in the U-Bending Process
Wiriyakorn Phanitwong; Untika Boochakul; Sutasn Thipprakmas
2017-01-01
The various U-geometry parameters in the U-bending process result in processing difficulties in the control of the spring-back characteristic. In this study, the effects of U-geometry parameters, including channel width, bend angle, material thickness, tool radius, as well as workpiece length, and their design, were investigated using a combination of finite element method (FEM) simulation, and statistical analysis techniques. Based on stress distribution analyses, the FEM simulation results ...
Directory of Open Access Journals (Sweden)
Issa Ahmed Abed
2016-12-01
Full Text Available This paper present a method to enhance the firefly algorithm by coupling with a local search. The constructed technique is applied to identify the solar parameters model where the method has been proved its ability to obtain the photovoltaic parameters model. Standard firefly algorithm (FA, electromagnetism-like (EM algorithm, and electromagnetism-like without local (EMW search algorithm all are compared with the suggested method to test its capability to solve this model.
Soncin, Rafael; Mezêncio, Bruno; Ferreira, Jacielle Carolina; Rodrigues, Sara Andrade; Huebner, Rudolf; Serrão, Julio Cerca; Szmuchrowski, Leszek
2017-06-01
The aim of this study was to propose a new force parameter, associated with swimmers' technique and performance. Twelve swimmers performed five repetitions of 25 m sprint crawl and a tethered swimming test with maximal effort. The parameters calculated were: the mean swimming velocity for crawl sprint, the mean propulsive force of the tethered swimming test as well as an oscillation parameter calculated from force fluctuation. The oscillation parameter evaluates the force variation around the mean force during the tethered test as a measure of swimming technique. Two parameters showed significant correlations with swimming velocity: the mean force during the tethered swimming (r = 0.85) and the product of the mean force square root and the oscillation (r = 0.86). However, the intercept coefficient was significantly different from zero only for the mean force, suggesting that although the correlation coefficient of the parameters was similar, part of the mean velocity magnitude that was not associated with the mean force was associated with the product of the mean force square root and the oscillation. Thus, force fluctuation during tethered swimming can be used as a quantitative index of swimmers' technique.
Sharkawi, K.-H.; Abdul-Rahman, A.
2013-09-01
to LoD4. The accuracy and structural complexity of the 3D objects increases with the LoD level where LoD0 is the simplest LoD (2.5D; Digital Terrain Model (DTM) + building or roof print) while LoD4 is the most complex LoD (architectural details with interior structures). Semantic information is one of the main components in CityGML and 3D City Models, and provides important information for any analyses. However, more often than not, the semantic information is not available for the 3D city model due to the unstandardized modelling process. One of the examples is where a building is normally generated as one object (without specific feature layers such as Roof, Ground floor, Level 1, Level 2, Block A, Block B, etc). This research attempts to develop a method to improve the semantic data updating process by segmenting the 3D building into simpler parts which will make it easier for the users to select and update the semantic information. The methodology is implemented for 3D buildings in LoD2 where the buildings are generated without architectural details but with distinct roof structures. This paper also introduces hybrid semantic-geometric 3D segmentation method that deals with hierarchical segmentation of a 3D building based on its semantic value and surface characteristics, fitted by one of the predefined primitives. For future work, the segmentation method will be implemented as part of the change detection module that can detect any changes on the 3D buildings, store and retrieve semantic information of the changed structure, automatically updates the 3D models and visualize the results in a userfriendly graphical user interface (GUI).
Wentworth, Mami Tonoe
Uncertainty quantification plays an important role when making predictive estimates of model responses. In this context, uncertainty quantification is defined as quantifying and reducing uncertainties, and the objective is to quantify uncertainties in parameter, model and measurements, and propagate the uncertainties through the model, so that one can make a predictive estimate with quantified uncertainties. Two of the aspects of uncertainty quantification that must be performed prior to propagating uncertainties are model calibration and parameter selection. There are several efficient techniques for these processes; however, the accuracy of these methods are often not verified. This is the motivation for our work, and in this dissertation, we present and illustrate verification frameworks for model calibration and parameter selection in the context of biological and physical models. First, HIV models, developed and improved by [2, 3, 8], describe the viral infection dynamics of an HIV disease. These are also used to make predictive estimates of viral loads and T-cell counts and to construct an optimal control for drug therapy. Estimating input parameters is an essential step prior to uncertainty quantification. However, not all the parameters are identifiable, implying that they cannot be uniquely determined by the observations. These unidentifiable parameters can be partially removed by performing parameter selection, a process in which parameters that have minimal impacts on the model response are determined. We provide verification techniques for Bayesian model calibration and parameter selection for an HIV model. As an example of a physical model, we employ a heat model with experimental measurements presented in [10]. A steady-state heat model represents a prototypical behavior for heat conduction and diffusion process involved in a thermal-hydraulic model, which is a part of nuclear reactor models. We employ this simple heat model to illustrate verification
Space Weather Parameters Computed on the Basis of the Magnetogram Inversion Technique
Institute of Scientific and Technical Information of China (English)
V. M. Mishin; M. F(o)rster; A.D. Bazarzhapov; T.I. Saifudinova; Y.A. Karavaev; P. Stauning; J. Watermann; V. Golovkov; S. Solovyev
2005-01-01
In this paper is given short description of the magnetogram inversion technique, MIT2, and of methods of calculation of some parameters of space weather. Are given also examples of new results, obtained using the MIT2 and solar wind data.
Forest parameter estimation using polarimetric SAR interferometry techniques at low frequencies
Energy Technology Data Exchange (ETDEWEB)
Lee, Seung-Kuk
2013-05-01
Polarimetric Synthetic Aperture Radar Interferometry (Pol-InSAR) is an active radar remote sensing technique based on the coherent combination of both polarimetric and interferometric observables. The Pol-InSAR technique provided a step forward in quantitative forest parameter estimation. In the last decade, airborne SAR experiments evaluated the potential of Pol-InSAR techniques to estimate forest parameters (e.g., the forest height and biomass) with high accuracy over various local forest test sites. This dissertation addresses the actual status, potentials and limitations of Pol-InSAR inversion techniques for 3-D forest parameter estimations on a global scale using lower frequencies such as L- and P-band. The multi-baseline Pol-InSAR inversion technique is applied to optimize the performance with respect to the actual level of the vertical wave number and to mitigate the impact of temporal decorrelation on the Pol-InSAR forest parameter inversion. Temporal decorrelation is a critical issue for successful Pol-InSAR inversion in the case of repeat-pass Pol-InSAR data, as provided by conventional satellites or airborne SAR systems. Despite the limiting impact of temporal decorrelation in Pol-InSAR inversion, it remains a poorly understood factor in forest height inversion. Therefore, the main goal of this dissertation is to provide a quantitative estimation of the temporal decorrelation effects by using multi-baseline Pol-InSAR data. A new approach to quantify the different temporal decorrelation components is proposed and discussed. Temporal decorrelation coefficients are estimated for temporal baselines ranging from 10 minutes to 54 days and are converted to height inversion errors. In addition, the potential of Pol-InSAR forest parameter estimation techniques is addressed and projected onto future spaceborne system configurations and mission scenarios (Tandem-L and BIOMASS satellite missions at L- and P-band). The impact of the system parameters (e.g., bandwidth
Chisolm, Eric
2012-01-01
This is an introduction to geometric algebra, an alternative to traditional vector algebra that expands on it in two ways: 1. In addition to scalars and vectors, it defines new objects representing subspaces of any dimension. 2. It defines a product that's strongly motivated by geometry and can be taken between any two objects. For example, the product of two vectors taken in a certain way represents their common plane. This system was invented by William Clifford and is more commonly known as Clifford algebra. It's actually older than the vector algebra that we use today (due to Gibbs) and includes it as a subset. Over the years, various parts of Clifford algebra have been reinvented independently by many people who found they needed it, often not realizing that all those parts belonged in one system. This suggests that Clifford had the right idea, and that geometric algebra, not the reduced version we use today, deserves to be the standard "vector algebra." My goal in these notes is to describe geometric al...
Load Reconstruction Technique Using D-Optimal Design and Markov Parameters
Directory of Open Access Journals (Sweden)
Deepak K. Gupta
2015-01-01
Full Text Available This paper develops a technique for identifying dynamic loads acting on a structure based on impulse response of the structure, also referred to as the system Markov parameters, and structure response measured at optimally placed sensors on the structure. Inverse Markov parameters are computed from the forward Markov parameters using a linear prediction algorithm and have the roles of input and output reversed. The applied loads are then reconstructed by convolving the inverse Markov parameters with the system response to the loads measured at optimal locations on the structure. The structure essentially acts as its own load transducer. It has been noted that the computation of inverse Markov parameters, like most other inverse problems, is ill-conditioned which causes their convolution with the measured response to become quite sensitive to errors in system modeling and response measurements. The computation of inverse Markov parameters (and thereby the quality of load estimates depends on the locations of sensors on the structure. To ensure that the computation of inverse Markov parameters is well-conditioned, a solution approach, based on the construction of D-optimal designs, is presented to determine the optimal sensor locations such that precise load estimates are obtained.
Directory of Open Access Journals (Sweden)
Rome Keith
2011-03-01
Full Text Available Abstract Background A clinical study was conducted to determine the intra and inter-rater reliability of digital scanning and the neutral suspension casting technique to measure six foot parameters. The neutral suspension casting technique is a commonly utilised method for obtaining a negative impression of the foot prior to orthotic fabrication. Digital scanning offers an alternative to the traditional plaster of Paris techniques. Methods Twenty one healthy participants volunteered to take part in the study. Six casts and six digital scans were obtained from each participant by two raters of differing clinical experience. The foot parameters chosen for investigation were cast length (mm, forefoot width (mm, rearfoot width (mm, medial arch height (mm, lateral arch height (mm and forefoot to rearfoot alignment (degrees. Intraclass correlation coefficients (ICC with 95% confidence intervals (CI were calculated to determine the intra and inter-rater reliability. Measurement error was assessed through the calculation of the standard error of the measurement (SEM and smallest real difference (SRD. Results ICC values for all foot parameters using digital scanning ranged between 0.81-0.99 for both intra and inter-rater reliability. For neutral suspension casting technique inter-rater reliability values ranged from 0.57-0.99 and intra-rater reliability values ranging from 0.36-0.99 for rater 1 and 0.49-0.99 for rater 2. Conclusions The findings of this study indicate that digital scanning is a reliable technique, irrespective of clinical experience, with reduced measurement variability in all foot parameters investigated when compared to neutral suspension casting.
Tohidi, Masoumeh; Toghraie, Davood
2017-08-01
The effect of geometrical parameters, roughness and the number of nanoparticles on self-diffusion in Couette flow in a nanochannel is investigated by using of molecular dynamics simulation. Gold nanoparticles (50, 100 and 200) were also distributed randomly between the nanochannel upper and lower walls. The effect of geometrical parameters of rectangular roughness in a nanochannel and the number of Gold nanoparticles on global self-diffusion and local self-diffusion as well as the average amounts were investigated in Couette flow. The results show that by increasing the roughness height, the particles are entrapped within the roughness and hence reduce the local self-diffusion coefficient in the vicinity of the upper wall. Also, by increasing the roughness height, the roughness length has less effect on the local diffusion coefficient.
Integrated search technique for parameter determination of SVM for speech recognition
Institute of Scientific and Technical Information of China (English)
Teena Mittal; R K Sharma
2016-01-01
Support vector machine (SVM) has a good application prospect for speech recognition problems;still optimum parameter selection is a vital issue for it. To improve the learning ability of SVM, a method for searching the optimal parameters based on integration of predator prey optimization (PPO) and Hooke-Jeeves method has been proposed. In PPO technique, population consists of prey and predator particles. The prey particles search the optimum solution and predator always attacks the global best prey particle. The solution obtained by PPO is further improved by applying Hooke-Jeeves method. Proposed method is applied to recognize isolated words in a Hindi speech database and also to recognize words in a benchmark database TI-20 in clean and noisy environment. A recognition rate of 81.5% for Hindi database and 92.2% for TI-20 database has been achieved using proposed technique.
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DR.S.C.JAYSWAL
2011-07-01
Full Text Available This experimental work presents a technique to determine the better surface quality by controlling the surface roughness and geometrical error. In machining operations, achieving desired surface quality features of the machined product is really a challenging job. Because, these quality features are highly correlated and areexpected to be influenced directly or indirectly by the direct effect of process parameters or their interactive effects. Thus The four input process parameters such as spindle speed, depth of cut, feed rate, and stepover have been selected to minimize the surface roughness and geometrical error simultaneously by using the robustdesign concept of Taguchi L9(34 method coupled with Response surface concept. Mathematical models for surface roughness and geometrical error were obtained from response surface analysis to predict values of surface roughness and geometrical error. S/N ratio and ANOVA analyses were also performed to obtain for significant parameters influencing surface roughness and geometrical error.
Active control and parameter updating techniques for nonlinear thermal network models
Papalexandris, M. V.; Milman, M. H.
The present article reports on active control and parameter updating techniques for thermal models based on the network approach. Emphasis is placed on applications where radiation plays a dominant role. Examples of such applications are the thermal design and modeling of spacecrafts and space-based science instruments. Active thermal control of a system aims to approximate a desired temperature distribution or to minimize a suitably defined temperature-dependent functional. Similarly, parameter updating aims to update the values of certain parameters of the thermal model so that the output approximates a distribution obtained through direct measurements. Both problems are formulated as nonlinear, least-square optimization problems. The proposed strategies for their solution are explained in detail and their efficiency is demonstrated through numerical tests. Finally, certain theoretical results pertaining to the characterization of solutions of the problems of interest are also presented.
Karuppusamy, S.; Dinesh Babu, K.; Nirmal Kumar, V.; Gopalakrishnan, R.
2016-05-01
The bulk acenaphthene crystal was grown in a single-wall ampoule by vertical Bridgman technique. X-ray diffraction analysis confirmed the orthorhombic crystal system of title compound with space group Pcm21. Thermal behavior of compound was studied using thermogravimetry—differential scanning calorimetry analysis. Thermal kinetic parameters like activation energy, frequency factor, Avrami exponent, reaction rate and degree of conversion were calculated using Kissingers and Ozawa methods under non-isothermal condition for acenaphthene crystal and reported for the first time. The calculated thermal kinetic parameters are presented. Dielectric studies were performed to calculate the dielectric parameters such as dielectric constant, dielectric loss, AC conductivity, and activation energy from Arrhenius plot.
Development of a parameter optimization technique for the design of automatic control systems
Whitaker, P. H.
1977-01-01
Parameter optimization techniques for the design of linear automatic control systems that are applicable to both continuous and digital systems are described. The model performance index is used as the optimization criterion because of the physical insight that can be attached to it. The design emphasis is to start with the simplest system configuration that experience indicates would be practical. Design parameters are specified, and a digital computer program is used to select that set of parameter values which minimizes the performance index. The resulting design is examined, and complexity, through the use of more complex information processing or more feedback paths, is added only if performance fails to meet operational specifications. System performance specifications are assumed to be such that the desired step function time response of the system can be inferred.
Measuring Structural Parameters of Knitted Fabrics by Digital Image Processing Techniques
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
In the knitting industry the measurements of the stitchdensity and the stitch length are usually done manually,which may lead to lower efficiency and less definition and also bring subjective ideas into the test results. In order to improve the effect we can measure with Digital Image Processing Techniques. A piece of sample is scanned into computer and changed into a digital image, which is processed with media filtering. To acquire the powerspectrum, the image in the spatial domain is converted into the frequency domain. Picking up the characteristic points describing the stitch density and the stitch length separately in the power spectra and reconstructing them, the values of the stitch density and the stitch length could be calculated.When measuring the stitch length, we should establish a geometric model of the stitch based on the digital image processing, which provides a method to transform the stitch length in the two-dimension space into the three-dimension space and to measure the value of the stitch length more accurately. This method also provides a new way to measure the stitch length without damaging the fabric.
Lee, H.; Choi, S.; Lee, D.; Kim, Y.-s.; Park, H.-S.; Lee, Y.; Seo, C.-W.; Kim, H.-J.
2017-08-01
Chest digital tomosynthesis (CDT) is a promising new modality that provides 3D information by reconstructing limited projection views. CDT systems have been developed to improve the limitations of conventional radiography such as image degradation and low sensitivity. However, the development of reconstruction methods is challenging because of the limited projection views within various angular ranges. Optimization of reconstruction parameters for various reconsturction methods in CDT system also is needed. The purpose of this study was to investigate the feasibility of algebraic reconstruction technique (ART) method, and to evaluate the effect of the reconstruction parameters for our newly developed CDT system. We designed ART method with 41 projection views over an angular range of ±20°. To investigate the effect of reconstruction parameters, we measured the contrast-to-noise ratio (CNR), artifact spread function (ASF), and quality factor (QF) using LUNGMAN phantom included tumors. We found that the proper choice of reconstruction parameters such as relaxation parameter, initial guess, and number of iterations improved the quality of reconstructed images from the same projection views. Optimal values of ART relaxation parameter with uniform (UI) and back-projection (BP) initial guesses were 0.4 and 0.6, respectively. BP initial guess improved image quality in comparison with UI initial guess, in terms of providing a higher CNR and QF values with a faster speed. CNR and QF values improved with increasing number of iteration. Particularly, ART method with BP initial guess (when β = 0.6) after 3-terations provide satisfactory reconstructed image. In conclusion, the use of ART method with proper reconstruction parameters provided better image quality than FBP method as well as conventional radiography. These results indicated that the ART method with optimal reconstruction parameters could improve image quality for nodule detection using the CDT system.
Application of separable parameter space techniques to multi-tracer PET compartment modeling
Zhang, Jeff L.; Morey, A. Michael; Kadrmas, Dan J.
2016-02-01
Multi-tracer positron emission tomography (PET) can image two or more tracers in a single scan, characterizing multiple aspects of biological functions to provide new insights into many diseases. The technique uses dynamic imaging, resulting in time-activity curves that contain contributions from each tracer present. The process of separating and recovering separate images and/or imaging measures for each tracer requires the application of kinetic constraints, which are most commonly applied by fitting parallel compartment models for all tracers. Such multi-tracer compartment modeling presents challenging nonlinear fits in multiple dimensions. This work extends separable parameter space kinetic modeling techniques, previously developed for fitting single-tracer compartment models, to fitting multi-tracer compartment models. The multi-tracer compartment model solution equations were reformulated to maximally separate the linear and nonlinear aspects of the fitting problem, and separable least-squares techniques were applied to effectively reduce the dimensionality of the nonlinear fit. The benefits of the approach are then explored through a number of illustrative examples, including characterization of separable parameter space multi-tracer objective functions and demonstration of exhaustive search fits which guarantee the true global minimum to within arbitrary search precision. Iterative gradient-descent algorithms using Levenberg-Marquardt were also tested, demonstrating improved fitting speed and robustness as compared to corresponding fits using conventional model formulations. The proposed technique overcomes many of the challenges in fitting simultaneous multi-tracer PET compartment models.
Directory of Open Access Journals (Sweden)
M. Santhakumar
2009-01-01
Full Text Available Hydrodynamic parameters play a major role in the dynamics and control of Autonomous Underwater Vehicles (AUVs. The performance of an AUV is dependent on the parameter variations and a proper understanding of these parametric influences is essential for the design, modeling, and control of high-performance AUVs. In this paper, the sensitivity of hydrodynamic parameters on the control of a flatfish type AUV is analyzed using robust design techniques such as Taguchi's design method and statistical analysis tools such as Pareto-ANOVA. Since the pitch angle of an AUV is one of the crucial variables in the control applications, the sensitivity analysis of pitch angle variation is studied here. Eight prominent hydrodynamic coefficients are considered in the analysis. The results show that there are two critical hydrodynamic parameters, that is, hydrodynamic force and hydrodynamic pitching moment in the heave direction that influence the performance of a flatfish type AUV. A near-optimal combination of the parameters was identified and the simulation results have shown the effectiveness of the method in reducing the pitch error. These findings are significant for the design modifications as well as controller design of AUVs.
Invariant sets techniques for Youla-Kučera parameter synthesis
Luca, Anamaria; Rodriguez-Ayerbe, Pedro; Dumur, Didier
2011-09-01
This article addresses an invariant sets approach for Youla-Kučera parameter synthesis using linear matrix inequality (LMI) techniques. Given a linear discrete-time observer-based system affected by bounded disturbances and constraints, the proposed technique furnishes the best Youla parameter in terms of finding an invariant ellipsoidal set satisfying the constraints and having the maximal ellipsoidal projection on the state space. Compared with the results obtained for an observer-based design, the synthesis of a Youla parameter provides a larger ellipsoidal projection and an improved sensitivity function. The price to pay for these achievements in terms of robustness is usually a slow closed-loop performance with degraded complementary sensitivity function. In order to obtain a compromise between robustness and performance two methods are proposed: the first method imposes a new bound on the Lyapunov function decreasing speed and the second refers to the pole placement concept. The aforementioned approaches are finally validated in simulation considering position control of an induction motor.
Consistency in Al/CuPc/ n-Si Heterojunction Diode Parameters Extracted Using Different Techniques
Ullah, Irfan; Shah, Mutabar; Khan, Majid; Wahab, Fazal
2016-02-01
This paper reports fabrication and characterization of an Al/CuPc/ n-Si heterojunction diode. The heterojunction was fabricated by depositing the active organic semiconducting material copper phthalocyanine (CuPc) on the n-Si substrate using the thermal vacuum evaporation technique. Electrical characterization of the fabricated heterojunction was carried out at ambient conditions. Various diode parameters, such as the ideality factor ( n), barrier height (Φ_{{b}}), and series resistance ( R s), were extracted from the current-voltage ( I- V) characteristic curve. These parameters are consistent with techniques used by Cheung, Norde and Hernandez et al. Furthermore these parameters are consistent with capacitance-voltage (C-V) characterization method. The conduction mechanism at the interface of CuPc and n-Si was also investigated. The surface morphology of the CuPc film was studied using atomic force microscopy and scanning electron microscopy. The optical bandgap of the CuPc film was calculated from the absorption spectrum using Tauc's law.
Energy Technology Data Exchange (ETDEWEB)
Bialasiewicz, J.T.
1995-06-01
The goal of this research is to develop advanced system identification techniques that can be used to accurately measure the frequency response functions of a wind-turbine structure immersed in wind noise. To allow for accurate identification, the authors have developed a special test signal called the Pseudo-Random Binary Sequence (PRBS). The Matlab program that generates this signal allows the user to interactively tailor its parameters for the frequency range of interest based on the response of the wind turbine under test. By controlling NREL`s Mobile Hydraulic Shaker System, which is attached to the wind turbine structure, the PRBS signal produces the wide-band excitation necessary to perform system identification in the presence of wind noise. The techniques presented here will enable researchers to obtain modal parameters from an operating wind turbine, including frequencies, damping coefficients, and mode shapes. More importantly, the algorithms they have developed and tested (so far using input-output data from a simulated structure) permit state-space representation of the system under test, particularly the modal state space representation. This is the only system description that reveals the internal behavior the system, such as the interaction between the physical parameters, and which, in contrast to transfer functions, is valid for non-zero initial conditions.
Geometric Time Delay Interferometry
Vallisneri, Michele
2005-01-01
The space-based gravitational-wave observatory LISA, a NASA-ESA mission to be launched after 2012, will achieve its optimal sensitivity using Time Delay Interferometry (TDI), a LISA-specific technique needed to cancel the otherwise overwhelming laser noise in the inter-spacecraft phase measurements. The TDI observables of the Michelson and Sagnac types have been interpreted physically as the virtual measurements of a synthesized interferometer. In this paper, I present Geometric TDI, a new an...
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Raju Bangalore Singe Gowda
2014-01-01
Full Text Available Rapid prototyping (RP has evolved as frontier technology in the recent times, which allows direct transformation of CAD files into functional prototypes where it tremendously reduces the lead time to produce physical prototypes necessary for design verification, fit, and functional analysis by generating the prototypes directly from the CAD data. Part quality in the rapid prototyping process is a function of build parameters such as hatch cure depth, layer thickness, orientation, and hatch spacing. Thus an attempt was made to identify, study, and optimize the process parameters governing the system which are related to part characteristics using Taguchi experimental design techniques quality. The part characteristics can be divided into physical part and mechanical part characteristics. The physical characteristics are surface finish, dimensional accuracy, distortion, layer thickness, hatch cure, and hatch file, whereas mechanical characteristics are flexural strength, ultimate tensile strength, and impact strength. Thus, this paper proposes to characterize the influence of the physical build parameters over the part quality. An L9 orthogonal array was designed with the minimum number of experimental runs with desired parameter settings and also by analysis tools such as ANOVA (analysis of variance. Establishment of experimentally verified correlations between the physical part characteristics and mechanical part characteristics to obtain an optimal process parameter level for betterment of part quality is obtained. The process model obtained by the empirical relation can be used to determine the strength of the prototype for the given set of parameters that shows the dependency of strength, which are essential for designers and RP machine users.
Optimization and effect of controlling parameters on AJM using Taguchi technique
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Jukti Prasad Padhy
2014-03-01
Full Text Available Abrasive Jet Machining (AJM is a non-conventional machining process where a high-pressure air stream with small abrasive particles to impinge the work surface through a nozzle. A model of AJM was designed by using CATIA. This model was implemented to design a workable AJM. In this paper drilling experiment was done on glass as the work piece and aluminum oxide (Al2O3 as abrasive powder on AJM. The air pressure and stand-off-distance (SOD are considering control parameter. The effect of Overcut (OC and Material Removal Rate (MRR of glass material was finding by using L9 Orthogonal Array (OA based on Taguchi design. And the influence of these controlling parameters is analyzed. Individual main effect of air pressure and SOD are plotted and optimized. Analysis of variance (ANOVA results were performed implementing Taguchi technique.
Lubineau, Gilles
2009-05-16
The post-processing of experiments with nonuniform fields is still a challenge: the information is often much richer, but its interpretation for identification purposes is not straightforward. However, this is a very promising field of development because it would pave the way for the robust identification of multiple material parameters using only a small number of experiments. This paper presents a goal-oriented filtering technique in which data are combined into new output fields which are strongly correlated with specific quantities of interest (the material parameters to be identified). Thus, this combination, which is nonuniform in space, constitutes a filter of the experimental outputs, whose relevance is quantified by a quality function based on global variance analysis. Then, this filter is optimized using genetic algorithms. © 2009 Springer-Verlag.
Model–Based Techniques for Virtual Sensing of Longitudinal Flight Parameters
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Seren Cédric
2015-03-01
Full Text Available Introduction of fly-by-wire and increasing levels of automation significantly improve the safety of civil aircraft, and result in advanced capabilities for detecting, protecting and optimizing A/C guidance and control. However, this higher complexity requires the availability of some key flight parameters to be extended. Hence, the monitoring and consolidation of those signals is a significant issue, usually achieved via many functionally redundant sensors to extend the way those parameters are measured. This solution penalizes the overall system performance in terms of weight, maintenance, and so on. Other alternatives rely on signal processing or model-based techniques that make a global use of all or part of the sensor data available, supplemented by a model-based simulation of the flight mechanics. That processing achieves real-time estimates of the critical parameters and yields dissimilar signals. Filtered and consolidated information is delivered in unfaulty conditions by estimating an extended state vector, including wind components, and can replace failed signals in degraded conditions. Accordingly, this paper describes two model-based approaches allowing the longitudinal flight parameters of a civil A/C to be estimated on-line. Results are displayed to evaluate the performances in different simulated and real flight conditions, including realistic external disturbances and modeling errors.
Transmuted Complementary Weibull Geometric Distribution
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Ahmed Z. A fify
2014-12-01
Full Text Available This paper provides a new generalization of the complementary Weibull geometric distribution that introduced by Tojeiro et al. (2014, using the quadratic rank transmutation map studied by Shaw and Buckley (2007. The new distribution is referred to as transmuted complementary Weibull geometric distribution (TCWGD. The TCWG distribution includes as special cases the complementary Weibull geometric distribution (CWGD, complementary exponential geometric distribution(CEGD,Weibull distribution (WD and exponential distribution (ED. Various structural properties of the new distribution including moments, quantiles, moment generating function and RØnyi entropy of the subject distribution are derived. We proposed the method of maximum likelihood for estimating the model parameters and obtain the observed information matrix. A real data set are used to compare the exibility of the transmuted version versus the complementary Weibull geometric distribution.
Ambrosetti, Antonio; Malchiodi, Andrea
2009-01-01
This volume contains lecture notes on some topics in geometric analysis, a growing mathematical subject which uses analytical techniques, mostly of partial differential equations, to treat problems in differential geometry and mathematical physics. The presentation of the material should be rather accessible to non-experts in the field, since the presentation is didactic in nature. The reader will be provided with a survey containing some of the most exciting topics in the field, with a series of techniques used to treat such problems.
Ahn, Kuk-Hyun; Palmer, Richard
2016-09-01
Despite wide use of regression-based regional flood frequency analysis (RFFA) methods, the majority are based on either ordinary least squares (OLS) or generalized least squares (GLS). This paper proposes 'spatial proximity' based RFFA methods using the spatial lagged model (SLM) and spatial error model (SEM). The proposed methods are represented by two frameworks: the quantile regression technique (QRT) and parameter regression technique (PRT). The QRT develops prediction equations for flooding quantiles in average recurrence intervals (ARIs) of 2, 5, 10, 20, and 100 years whereas the PRT provides prediction of three parameters for the selected distribution. The proposed methods are tested using data incorporating 30 basin characteristics from 237 basins in Northeastern United States. Results show that generalized extreme value (GEV) distribution properly represents flood frequencies in the study gages. Also, basin area, stream network, and precipitation seasonality are found to be the most effective explanatory variables in prediction modeling by the QRT and PRT. 'Spatial proximity' based RFFA methods provide reliable flood quantile estimates compared to simpler methods. Compared to the QRT, the PRT may be recommended due to its accuracy and computational simplicity. The results presented in this paper may serve as one possible guidepost for hydrologists interested in flood analysis at ungaged sites.
Geometric inequalities for black holes
Energy Technology Data Exchange (ETDEWEB)
Dain, Sergio [Universidad Nacional de Cordoba (Argentina)
2013-07-01
Full text: A geometric inequality in General Relativity relates quantities that have both a physical interpretation and a geometrical definition. It is well known that the parameters that characterize the Kerr-Newman black hole satisfy several important geometric inequalities. Remarkably enough, some of these inequalities also hold for dynamical black holes. This kind of inequalities, which are valid in the dynamical and strong field regime, play an important role in the characterization of the gravitational collapse. They are closed related with the cosmic censorship conjecture. In this talk I will review recent results in this subject. (author)
Pragmatic geometric model evaluation
Pamer, Robert
2015-04-01
Quantification of subsurface model reliability is mathematically and technically demanding as there are many different sources of uncertainty and some of the factors can be assessed merely in a subjective way. For many practical applications in industry or risk assessment (e. g. geothermal drilling) a quantitative estimation of possible geometric variations in depth unit is preferred over relative numbers because of cost calculations for different scenarios. The talk gives an overview of several factors that affect the geometry of structural subsurface models that are based upon typical geological survey organization (GSO) data like geological maps, borehole data and conceptually driven construction of subsurface elements (e. g. fault network). Within the context of the trans-European project "GeoMol" uncertainty analysis has to be very pragmatic also because of different data rights, data policies and modelling software between the project partners. In a case study a two-step evaluation methodology for geometric subsurface model uncertainty is being developed. In a first step several models of the same volume of interest have been calculated by omitting successively more and more input data types (seismic constraints, fault network, outcrop data). The positions of the various horizon surfaces are then compared. The procedure is equivalent to comparing data of various levels of detail and therefore structural complexity. This gives a measure of the structural significance of each data set in space and as a consequence areas of geometric complexity are identified. These areas are usually very data sensitive hence geometric variability in between individual data points in these areas is higher than in areas of low structural complexity. Instead of calculating a multitude of different models by varying some input data or parameters as it is done by Monte-Carlo-simulations, the aim of the second step of the evaluation procedure (which is part of the ongoing work) is to
Testing algebraic geometric codes
Institute of Scientific and Technical Information of China (English)
CHEN Hao
2009-01-01
Property testing was initially studied from various motivations in 1990's.A code C (∩)GF(r)n is locally testable if there is a randomized algorithm which can distinguish with high possibility the codewords from a vector essentially far from the code by only accessing a very small (typically constant) number of the vector's coordinates.The problem of testing codes was firstly studied by Blum,Luby and Rubinfeld and closely related to probabilistically checkable proofs (PCPs).How to characterize locally testable codes is a complex and challenge problem.The local tests have been studied for Reed-Solomon (RS),Reed-Muller (RM),cyclic,dual of BCH and the trace subcode of algebraicgeometric codes.In this paper we give testers for algebraic geometric codes with linear parameters (as functions of dimensions).We also give a moderate condition under which the family of algebraic geometric codes cannot be locally testable.
Testing algebraic geometric codes
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Property testing was initially studied from various motivations in 1990’s. A code C GF (r)n is locally testable if there is a randomized algorithm which can distinguish with high possibility the codewords from a vector essentially far from the code by only accessing a very small (typically constant) number of the vector’s coordinates. The problem of testing codes was firstly studied by Blum, Luby and Rubinfeld and closely related to probabilistically checkable proofs (PCPs). How to characterize locally testable codes is a complex and challenge problem. The local tests have been studied for Reed-Solomon (RS), Reed-Muller (RM), cyclic, dual of BCH and the trace subcode of algebraicgeometric codes. In this paper we give testers for algebraic geometric codes with linear parameters (as functions of dimensions). We also give a moderate condition under which the family of algebraic geometric codes cannot be locally testable.
A Comprehensive Review on Water Quality Parameters Estimation Using Remote Sensing Techniques
Directory of Open Access Journals (Sweden)
Mohammad Haji Gholizadeh
2016-08-01
Full Text Available Remotely sensed data can reinforce the abilities of water resources researchers and decision makers to monitor waterbodies more effectively. Remote sensing techniques have been widely used to measure the qualitative parameters of waterbodies (i.e., suspended sediments, colored dissolved organic matter (CDOM, chlorophyll-a, and pollutants. A large number of different sensors on board various satellites and other platforms, such as airplanes, are currently used to measure the amount of radiation at different wavelengths reflected from the water’s surface. In this review paper, various properties (spectral, spatial and temporal, etc. of the more commonly employed spaceborne and airborne sensors are tabulated to be used as a sensor selection guide. Furthermore, this paper investigates the commonly used approaches and sensors employed in evaluating and quantifying the eleven water quality parameters. The parameters include: chlorophyll-a (chl-a, colored dissolved organic matters (CDOM, Secchi disk depth (SDD, turbidity, total suspended sediments (TSS, water temperature (WT, total phosphorus (TP, sea surface salinity (SSS, dissolved oxygen (DO, biochemical oxygen demand (BOD and chemical oxygen demand (COD.
A Comprehensive Review on Water Quality Parameters Estimation Using Remote Sensing Techniques
Gholizadeh, Mohammad Haji; Melesse, Assefa M.; Reddi, Lakshmi
2016-01-01
Remotely sensed data can reinforce the abilities of water resources researchers and decision makers to monitor waterbodies more effectively. Remote sensing techniques have been widely used to measure the qualitative parameters of waterbodies (i.e., suspended sediments, colored dissolved organic matter (CDOM), chlorophyll-a, and pollutants). A large number of different sensors on board various satellites and other platforms, such as airplanes, are currently used to measure the amount of radiation at different wavelengths reflected from the water’s surface. In this review paper, various properties (spectral, spatial and temporal, etc.) of the more commonly employed spaceborne and airborne sensors are tabulated to be used as a sensor selection guide. Furthermore, this paper investigates the commonly used approaches and sensors employed in evaluating and quantifying the eleven water quality parameters. The parameters include: chlorophyll-a (chl-a), colored dissolved organic matters (CDOM), Secchi disk depth (SDD), turbidity, total suspended sediments (TSS), water temperature (WT), total phosphorus (TP), sea surface salinity (SSS), dissolved oxygen (DO), biochemical oxygen demand (BOD) and chemical oxygen demand (COD). PMID:27537896
Design of U-Geometry Parameters Using Statistical Analysis Techniques in the U-Bending Process
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Wiriyakorn Phanitwong
2017-06-01
Full Text Available The various U-geometry parameters in the U-bending process result in processing difficulties in the control of the spring-back characteristic. In this study, the effects of U-geometry parameters, including channel width, bend angle, material thickness, tool radius, as well as workpiece length, and their design, were investigated using a combination of finite element method (FEM simulation, and statistical analysis techniques. Based on stress distribution analyses, the FEM simulation results clearly identified the different bending mechanisms and effects of U-geometry parameters on the spring-back characteristic in the U-bending process, with and without pressure pads. The statistical analyses elucidated that the bend angle and channel width have a major influence in cases with and without pressure pads, respectively. The experiments were carried out to validate the FEM simulation results. Additionally, the FEM simulation results were in agreement with the experimental results, in terms of the bending forces and bending angles.
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Marcelo Ribeiro dos Santos
2014-01-01
Full Text Available During machining energy is transformed into heat due to plastic deformation of the workpiece surface and friction between tool and workpiece. High temperatures are generated in the region of the cutting edge, which have a very important influence on wear rate of the cutting tool and on tool life. This work proposes the estimation of heat flux at the chip-tool interface using inverse techniques. Factors which influence the temperature distribution at the AISI M32C high speed steel tool rake face during machining of a ABNT 12L14 steel workpiece were also investigated. The temperature distribution was predicted using finite volume elements. A transient 3D numerical code using irregular and nonstaggered mesh was developed to solve the nonlinear heat diffusion equation. To validate the software, experimental tests were made. The inverse problem was solved using the function specification method. Heat fluxes at the tool-workpiece interface were estimated using inverse problems techniques and experimental temperatures. Tests were performed to study the effect of cutting parameters on cutting edge temperature. The results were compared with those of the tool-work thermocouple technique and a fair agreement was obtained.
Institute of Scientific and Technical Information of China (English)
徐玉茹; 徐付霞
2016-01-01
证明了几何分布参数的充分统计量服从负二项分布，由此将负二项分布转化为生存贝塔分布，构造出了参数的精确置信区间，并且在不同的置信度组合中选出最佳组合，得到精确最短置信区间。讨论了大样本下几何分布的近似区间估计，通过数值模拟，直观展示区间估计的精度变化，说明了精确最短区间估计的优良性。%This paper proved that the sufficient statistic of a geometric distribution parameter is subjected to the negative binomial distribution .Therefore, constructed the exact confi-dence interval of the parameter by converting the negative binomial distribution into the sur -vival beta distribution, and select the best combination in different levels of the confidence to get the accurate shortest confidence interval of its parameter .The approximate interval esti-mate under the large sample of a geometric distribution was discussed in this paper .Through numerical simulation, the change of the accuracy of an interval estimation was intuitively demonstrated, and then the superiority of the accurate shortest confidence interval was illus -trated.
Cong, Jiawei; Yun, Binfeng; Cui, Yiping
2013-08-26
By introducing the frequency tuning sensitivity, an analytical model based on equivalent LC circuit is developed for the relative frequency tuning range of THz semiconductor split-ring resonator (SRR). And the model reveals that the relative tuning range is determined by the ratio of the kinetic inductance to the geometric inductance (RKG). The results show that under the same carrier density variation, a larger RKG results in a larger relative tuning range. Based on this model, a stacked SRR-dimer structure with larger RKG compared to the single SRR due to the inductive coupling is proposed, which improves the relative tuning range effectively. And the results obtained by the simple analytical model agree well with the numerical FDTD results. The presented analytical model is robust and can be used to analyze the relative frequency tuning of other tunable THz devices.
A spatial bootstrap technique for parameter estimation of rainfall annual maxima distribution
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F. Uboldi
2013-09-01
Full Text Available Estimation of extreme event distributions and depth-duration-frequency (DDF curves is achieved at any target site by repeated sampling among all available raingauge data in the surrounding area. The estimate is computed over a gridded domain in Northern Italy, using precipitation time series from 1929 to 2011, including data from historical analog stations and from the present-day automatic observational network. The presented local regionalisation naturally overcomes traditional station-point methods, with their demand of long historical series and their sensitivity to very rare events occurring at very few stations, possibly causing unrealistic spatial gradients in DDF relations. At the same time, the presented approach allows for spatial dependence, necessary in a geographical domain such as Lombardy, complex for both its topography and its climatology. The bootstrap technique enables evaluating uncertainty maps for all estimated parameters and for rainfall depths at assigned return periods.
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Jyoti V. Dube
2014-01-01
Full Text Available Background: Caesarean section has been a part of human culture since ancient times. It has been used effectively throughout the 20th century and among the major abdominal surgeries, it is the most common, oldest worldwide surgery performed in obstetrics. Despite the life saving advantages, there are several adverse consequences of caesarean delivery for a woman and to her household. The rate and risk of these complications increases due to the increasing incidence mainly in countries like India. The role of nurse midwife is to act in the best interest of patient and newborn and make the patient independent in carrying out the activities of daily living as soon as possible. This can lead to a faster recovery and shorter hospital stay. Also it can indirectly help in reducing the complications associated with prolonged bed rest and can improve the maternal newborn bonding. Aim and Objectives: The present study was done to evaluate the effect of planned early ambulation on selected biophysiological health parameters of post caesarean patients. Material and Methods: The study included total 500 study subjects, 250 in experimental and 250 in control group. Quasi experimental approach with multiple time series design was adopted for the study. The experimental group was given an early planned recommended ambulation technique starting from the day of surgery. This consisted of deep breathing exercise, cough exercise, leg exercise and early mobilization. Over and above, the routine general health care was given by the doctors and nurses. The control group received only by routine general care by doctors and nurses and mobilization on third post operative day as per strategy adopted by the hospital. The deep breathing exercises, coughing exercises and leg exercises were not given routinely and hence were not given to the control group. Post caesarean biophysiological parameters chart was used to assess the selected parameters for first five post operative
Institute of Scientific and Technical Information of China (English)
黄小伟; 习俊通; J. L. Lebrun; Elcheikh Hussam; Courant Bruno
2011-01-01
激光熔覆技术经多年发展已取得许多成功的工业应用,但如何控制工艺以达到最佳成形效果,需要通过研究工艺参数与成形精度之间的关系才能找到最终的解决方案.借助激光熔覆快速成形法制备316L不锈钢实验试样,研究工艺参数组合对成形试样形状的影响规律.通过定义单涂覆层截面形状特征参数,采用线性相关法处理截面形状数据,建立工艺参数组合与截面形状特征参数的线性关系.此外,激光熔覆成形件易出现两类典型缺陷,即晶界间微裂纹和层间熔合不良缺陷.%After years of development of laser cladding forming technology, it has made many successful industrial applications. However, how to control the process to achieve the best forming results? We need study the relationship between the processing parameters and the forming accuracy to find the ultimate best solution. We prepare the 316L stainless steel specimens using the laser cladding forming to investigate the influences of processing parameters on geometric characterizations. Five parameters are defined to describe the geometric characterization of single layer cross section, and then the measurement data is processed with the linear regression method to establish relations between processing parameters and defined parameters. In addition, the laser cladding parts prone to two types of typical defects: micro-cracks between grain boundaries and poor fusion defects between two layers.
Cho, Hyunjoong
The accuracy of process simulation in metal forming by finite element method depends on the accuracy of flow stress data and friction value that are input to FEM programs. Therefore, it is essential that these input values are determined using reliable tests and evaluation methods. This study presents the development of inverse analysis methodology and its application to determine flow stress data of bulk and sheet materials at room and elevated temperatures. The inverse problem is defined as the minimization of the differences between the experimental measurements and the corresponding FEM predictions. Rigid-viscoplastic FEM is used to analyze the metal flow while a numerical optimization algorithm adjusts the material parameters used in the simulation until the calculated response matches the measured data within a specified tolerance. The use of the developed inverse analysis methodology has been demonstrated by applying it to the selected reference rheological tests; cylinder compression test, ring compression test, instrumented indentation test, modified limiting dome height test, and sheet hydraulic bulge test. Furthermore, using the determined material property data, full 3-D finite element simulation models, as examples of industrial applications for orbital forming and thermoforming processes have been developed for reliable process simulation. As results of this study, it was shown that the developed inverse analysis methodology could identify both the material parameters and friction factors from one set of tests, simultaneously. Therefore, this technique can offer a systematic and cost effective way for determining material property data for simulation of metal forming processes.
Joe, Paula S; Ito, Yasushi; Shih, Alan M; Oestenstad, Riedar K; Lungu, Claudiu T
2012-01-01
This study was designed to determine if three-dimensional (3D) laser scanning techniques could be used to collect accurate anthropometric measurements, compared with traditional methods. The use of an alternative 3D method would allow for quick collection of data that could be used to change the parameters used for facepiece design, improving fit and protection for a wider variety of faces. In our study, 10 facial dimensions were collected using both the traditional calipers and tape method and a Konica-Minolta Vivid9i laser scanner. Scans were combined using RapidForm XOR software to create a single complete facial geometry of the subject as a triangulated surface with an associated texture image from which to obtain measurements. A paired t-test was performed on subject means in each measurement by method. Nine subjects were used in this study: five males (one African-American and four Caucasian females) and four females displaying a range of facial dimensions. Five measurements showed significant differences (pLaser scanning measurements showed high precision and accuracy when compared with traditional methods. Significant differences found can be very small changes in measurements and are unlikely to present a practical difference. The laser scanning technique demonstrated reliable and quick anthropometric data collection for use in future projects in redesigning respirators.
Optimization of process parameters during vibratory welding technique using Taguchi's analysis
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Pravin Kumar Singh
2016-09-01
Full Text Available With an aim to improve the mechanical properties of a weld joint, a new concept of vibratory setup has been designed which is capable to stir the molten weld pool before it solidifies during shielded metal arc welding (SMAW operation. Mechanical vibration having resonance frequency of 300 Hz and amplitude of 0.5 mm was transferred to the molten weld pool of 6 mm thick mild steel butt-welded joints during the welding operation. The experimental work was conducted at various ranges of frequencies, welding current and welding speed. Taguchi's analysis technique has been applied to optimize the process parameters; the response values for analysis are yield strength and micro-hardness. The test results showed that with the application of the vibratory treatment the values of hardness and tensile properties increased. The auxiliary vibrations induced into the weld pool resulted in increased micro-hardness of the weld metal which indicates the orientation of the crystal and refinement of grains took place. This study shows that vibration applied into the weld pool can be successfully improved the mechanical properties of welded joints. Thus this research attempt provided an alternative welding technique for grain refinement of weldments.
Huisman, Jef; Sommeijer, Ben
2002-10-01
Phytoplankton use light for photosynthesis, and the light flux decreases with depth. As a result of this simple light dependence, reaction-advection-diffusion models describing the dynamics of phytoplankton species contain an integral over depth. That is, models that simulate phytoplankton dynamics in relation to mixing processes generally have the form of an integro-partial differential equation (integro-PDE). Integro-PDEs are computationally more demanding than standard PDEs. Here, we outline a reliable and efficient technique for numerical simulation of integro-PDEs. The simulation technique is illustrated by several examples on the population dynamics of sinking phytoplankton, using both single-species models and competition models with several phytoplankton species. Our results confirm recent findings that Sverdrup's critical-depth theory breaks down if turbulent mixing is reduced below a critical turbulence. In fact, our results show that suitable conditions for bloom development of sinking phytoplankton depend on a number of critical parameters, including a minimal depth of the thermocline, a maximal depth of the thermocline, a minimal turbulence, and a maximal turbulence. We therefore conclude that models that do not carefully consider the population dynamics of phytoplankton in relation to the turbulence structure of the water column may easily lead to erroneous predictions.
Technique for Calculating Solution Derivatives With Respect to Geometry Parameters in a CFD Code
Mathur, Sanjay
2011-01-01
A solution has been developed to the challenges of computation of derivatives with respect to geometry, which is not straightforward because these are not typically direct inputs to the computational fluid dynamics (CFD) solver. To overcome these issues, a procedure has been devised that can be used without having access to the mesh generator, while still being applicable to all types of meshes. The basic approach is inspired by the mesh motion algorithms used to deform the interior mesh nodes in a smooth manner when the surface nodes, for example, are in a fluid structure interaction problem. The general idea is to model the mesh edges and nodes as constituting a spring-mass system. Changes to boundary node locations are propagated to interior nodes by allowing them to assume their new equilibrium positions, for instance, one where the forces on each node are in balance. The main advantage of the technique is that it is independent of the volumetric mesh generator, and can be applied to structured, unstructured, single- and multi-block meshes. It essentially reduces the problem down to defining the surface mesh node derivatives with respect to the geometry parameters of interest. For analytical geometries, this is quite straightforward. In the more general case, one would need to be able to interrogate the underlying parametric CAD (computer aided design) model and to evaluate the derivatives either analytically, or by a finite difference technique. Because the technique is based on a partial differential equation (PDE), it is applicable not only to forward mode problems (where derivatives of all the output quantities are computed with respect to a single input), but it could also be extended to the adjoint problem, either by using an analytical adjoint of the PDE or a discrete analog.
Tanifuji, T.
2016-03-01
Time-resolved multi-distance measurements are studied to retrieve absorption and reduced scattering coefficients of adult heads, which have enough depth sensitivity to determine the optical parameters in superficial tissues and brain separately. Measurements were performed by putting the injection and collection fibers on the left semi-sphere of the forehead, with the injection fiber placed toward the temporal region, and by moving the collection fiber between 10 and 60 mm from the central sulcus. It became clear that optical parameters of the forehead at all collection fibers were reasonably determined by selecting the appropriate visibility length of the geometrical head models, which is related to head surface curvature at each position.
Koeppe, Robert Allen
Positron computed tomography (PCT) is a diagnostic imaging technique that provides both three dimensional imaging capability and quantitative measurements of local tissue radioactivity concentrations in vivo. This allows the development of non-invasive methods that employ the principles of tracer kinetics for determining physiological properties such as mass specific blood flow, tissue pH, and rates of substrate transport or utilization. A physiologically based, two-compartment tracer kinetic model was derived to mathematically describe the exchange of a radioindicator between blood and tissue. The model was adapted for use with dynamic sequences of data acquired with a positron tomograph. Rapid estimation techniques were implemented to produce functional images of the model parameters by analyzing each individual pixel sequence of the image data. A detailed analysis of the performance characteristics of three different parameter estimation schemes was performed. The analysis included examination of errors caused by statistical uncertainties in the measured data, errors in the timing of the data, and errors caused by violation of various assumptions of the tracer kinetic model. Two specific radioindicators were investigated. ('18)F -fluoromethane, an inert freely diffusible gas, was used for local quantitative determinations of both cerebral blood flow and tissue:blood partition coefficient. A method was developed that did not require direct sampling of arterial blood for the absolute scaling of flow values. The arterial input concentration time course was obtained by assuming that the alveolar or end-tidal expired breath radioactivity concentration is proportional to the arterial blood concentration. The scale of the input function was obtained from a series of venous blood concentration measurements. The method of absolute scaling using venous samples was validated in four studies, performed on normal volunteers, in which directly measured arterial concentrations
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Rosenda Valdés Arencibia
2011-03-01
Full Text Available Este trabalho apresenta uma metodologia para estimar a incerteza associada à medição dos parâmetros que definem a geometria do cordão de solda, especificamente da área do cordão, de forma a atender à exigência estabelecida pela norma NBR ISO/IEC 17025. A qualidade geométrica dos corpos de prova utilizados durante as medições foi ainda avaliada através da medição dos desvios geométricos de planeza e de perpendicularidade. As seguintes etapas foram propostas e realizadas: identificação dos parâmetros que definem a geometria do cordão de solda; identificação e estudo das variáveis que afetam a medição destes parâmetros; adoção do modelo matemático para estimativa da incerteza de cada parâmetro; planejamento e execução dos experimentos para o levantamento dos dados, cálculo da incerteza e, finalmente, análise e discussão dos resultados. Através da análise dos resultados foi possível concluir que as incertezas provenientes da calibração do sistema de medição e relativa ao desvio de perpendicularidade contribuíram significativamente para a incerteza final. As análises despertaram uma preocupação com relação aos valores permissíveis para o desvio de perpendicularidade dos corpos de prova utilizados durante as medições.This work presents a methodology to estimate the uncertainty associated to the measurement of the weld bead geometric parameters in order to address the requirements of NBR ISO/IEC 17025 Standard. The specimen geometric quality was additionally evaluated through the measurement of flatness and perpendicularity deviations. The following steps were proposed and executed: identification of weld bead geometric parameters; identification and study of the variables that affect measurement of the identified parameters; adoption of a mathematical model to estimate the uncertainty for each parameter; planning and execution of the experiments for data obtaining; uncertainty determination, analysis
Control of chaos in excitable physiological systems: A geometric analysis.
Christini, David J.; Collins, James J.
1997-12-01
Model-independent chaos control techniques are inherently well-suited for the control of physiological systems for which quantitative system models are unavailable. The proportional perturbation feedback (PPF) control paradigm, which uses electrical stimulation to perturb directly the controlled system variable (e.g., the interbeat or interspike interval), was developed for excitable physiological systems that do not have an easily accessible system parameter. We develop the stable manifold placement (SMP) technique, a PPF-type technique which is simpler and more robust than the original PPF control algorithm. We use the SMP technique to control a simple geometric model of a chaotic system in the neighborhood of an unstable periodic orbit (UPO). We show that while the SMP technique can control a chaotic system that has UPO dynamics which are characterized by one stable manifold and one unstable manifold, the success of the SMP technique is sensitive to UPO parameter estimation errors. (c) 1997 American Institute of Physics.
Pathak, P. H.; Kouyoumjian, R. G.
1974-01-01
In this paper the geometrical theory of diffraction is extended to treat the radiation from apertures of slots in convex perfectly conducting surfaces. It is assumed that the tangential electric field in the aperture is known so that an equivalent infinitesimal source can be defined at each point in the aperture. Surface rays emanate from this source which is a caustic of the ray system. A launching coefficient is introduced to describe the excitation of the surface ray modes. If the field radiated from the surface is desired, the ordinary diffraction coefficients are used to determine the field of the rays shed tangentially from the surface rays. The field of the surface ray modes is not the field on the surface; hence if the mutual coupling between slots is of interest, a second coefficient related to the launching coefficient must be employed. In the region adjacent to the shadow boundary, the component of the field directly radiated from the source is represented by Fock-type functions. In the illuminated region the incident radiation from the source (this does not include the diffracted field components) is treated by geometrical optics. This extension of the geometrical theory of diffraction is applied to calculate the radiation from slots on elliptic cylinders, spheres, and spheroids.
Direct scheme for measuring the geometric quantum discord
Jin, Jia-sen; Yu, Chang-shui; Song, He-shan
2011-01-01
We propose a scheme to directly measure the exact value of geometric quantum discord of an arbitrary two-qubit state. We only need to perform the projective measurement in the all anti-symmetric subspace and our scheme is parametrically efficient in contrast to the widely adopted quantum state tomography scheme in the sense of less parameter estimations and projectors. Moreover, the present scheme can be easily realized with the current experimental techniques.
Institute of Scientific and Technical Information of China (English)
田林; 徐世杰
2011-01-01
谐波齿轮为一类新型传动器件,结构紧凑且运动传递过程复杂.为形象理解谐波齿轮,以受到关注较少的滚珠活齿谐波齿轮为例建立其几何模型,通过数值计算对其关键参数进行了优化设计.根据几何模型及参数优化结果在ADAMS中建立该型谐波齿轮的实体模型,分常值和正弦指令转速两种情况进行了仿真.数值仿真结果与几何模型相符,直观地反映了谐波齿轮的传动特性,研究为含有谐波齿轮的传动系统建模打下了基础.%Harmonic gear reducer is a new kind of transmission device with compact structure and complicated motion transfer process. Aiming to understand harmonic gear reducer intuitionally, a geometric model is established according to the example of movable roller harmonic gear reducer which attracts little attention. Several key parameters are optimized by numeric calculation. According to the geometric model and optimization result, a solid model is developed in ADAMS. Simulation taking two instances of constant and sinusoidal speed command into account is done in ADAMS. The numeric simulation result is coincident with the geometric model and reflects the transmission characteristics of harmonic gear reducer vividly. The study lays a foundation for modeling of transmission system containing harmonic gear reducer.
Geometric constraint solving with geometric transformation
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
This paper proposes two algorithms for solving geometric constraint systems. The first algorithm is for constrained systems without loops and has linear complexity. The second algorithm can solve constraint systems with loops. The latter algorithm is of quadratic complexity and is complete for constraint problems about simple polygons. The key to it is to combine the idea of graph based methods for geometric constraint solving and geometric transformations coming from rule-based methods.
Hänel, G
1994-10-20
Complete sets of optical parameters of dry particles sampled on a Nuclepore filter are derived through interpretation of photometric data with an improved inversion technique. The parameters are the volume-extinction and absorption coefficients, the single-scattering albedo, the asymmetry parameter of the volume scattering function, the apparent complex refractive index, and the apparent soot content. They may serve as input data for solar radiation-budget considerations. Results from preliminary measurements taken in Central Europe and Italy show an extreme variability of the optical parameters. Both large regional and temporal variabilities have been observed caused by the fluctuating midlatitude weather systems and human activities.
Institute of Scientific and Technical Information of China (English)
ZHANG Hong-xia; XU Li-sheng; CHEN Yun-tai; LI Chun-lai; Klaus Stammler
2008-01-01
In this paper, we briefly describe the principle of tracking energy radiation sources of large earthquakes using frequency-domain far-field array technique, present general steps of tracking energy radiation sources, and take the 2001 Kunlun Mountain Pass earthquake as an example to analyze key factors for setting parameters while processing data. Using broadband waveform data from a seismic array in Ethiopia and Kenya (EK Array), we obtain that the rapture initiation point of the 2001 Kunlun Mountain Pass earthquake is located in the east of Buka Daban Peak (35.92°N, 91.70°E), and the rupture duration time is less than 160 s, the rupture length about 520 km, with 180 km in the west of the initiation point and 340 km in the east, respectively. The western segment of the earthquake fault bends towards southwest near Buka Daban Peak, which is in concordance with the surface rupture trace. The eastern segment apparently bends towards northeast near Xidatan, which is in agreement with the strike of Xidatan fault, but 30 km away from Xidatan fault. In addition, the results imply that the western segment of the earthquake fault appears erect while the eastern segment appears to be gradually dipping southwards.
Energy Technology Data Exchange (ETDEWEB)
Kang, Eun Ju; Lee, Ki Nam; Cho, Won Jin; Kim, Young Dae [College of Medicine, Dong-A University, Busan (Korea, Republic of); Shin, Kyung Min; Lim, Jae Kwang; Lee, Jong Min [Dept. of Radiology, Kyungpook National University, Daegu (Korea, Republic of)
2017-08-01
To assess the normal reference values of left ventricle (LV) functional parameters in Korean adults on coronary CT angiography (CCTA) with a 320-detector-row CT scanner, and to analyze sex-related differences and correlations with various clinical characteristics. This study retrospectively enrolled 172 subjects (107 men and 65 women; age, 58 ± 10.9 years; body surface area [BSA], 1.75 ± 0.2 m{sup 2}) who underwent CCTA without any prior history of cardiac disease. The following parameters were measured by post-processing the CT data: LV volume, LV functional parameters (ejection fraction, stroke volume, cardiac output, etc.), LV myocardial mass, LV inner diameter, and LV myocardial thickness (including septal wall thickness [SWT], posterior wall thickness [PWT], and relative wall thickness [RWT = 2 × PWT / LV inner diameter]). All of the functional or volumetric parameters were normalized using the BSA. The general characteristics and co-morbidities for the enrolled subjects were recorded, and the correlations between these factors and the LV parameters were then evaluated. The LV myocardial thickness (SWT, 1.08 ± 0.18 cm vs. 0.90 ± 0.17 cm, p < 0.001; PWT, 0.91 ± 0.15 cm vs. 0.78 ± 0.10 cm, p < 0.001; RWT, 0.38 ± 0.08 cm vs. 0.33 ± 0.05 cm, p < 0.001), LV volume (LV end-diastolic volume, 112.9 ± 26.1 mL vs. 98.2 ± 21.0 mL, p < 0.001; LV end-systolic volume, 41.7 ± 14.7 mL vs. 33.7 ± 12.2 mL, p = 0.001) and mass (145.0 ± 29.1 g vs. 107.9 ± 20.0 g, p < 0.001) were significantly greater in men than in women. However, these differences were not significant after normalization using BSA, except for the LV mass (LV mass index, 79.6 ± 14.0 g/m{sup 2} vs. 66.2 ± 11.0 g/m{sup 2},p < 0.001). The cardiac output and ejection fraction were not significantly different between the men and women (cardiac output, 4.3 ± 1.0 L/min vs. 4.2 ± 0.9 L/min, p = 0.452; ejection fraction, 63.4 ± 7.7% vs. 66.4 ± 7.6%, p = 0.079). Most of the LV parameters were
Wong, Allan C. L.; Childs, Paul A.; Peng, Gang-Ding
2007-11-01
A multiplexing technique using amplitude-modulated chirped fibre Bragg gratings (AMCFBGs) is presented. This technique realises the multiplexing of spectrally overlapped AMCFBGs with identical centre Bragg wavelength and bandwidth. Since it is fully compatible with the wavelength division multiplexing scheme, the number of gratings that can be multiplexed can be increased by several times. The discrete wavelet transform is used to demodulate such multiplexed signal. A wavelet denoising technique is applied to the multiplexed signal in conjunction with the demodulation. Strain measurements are performed to experimentally demonstrate the feasibility of this multiplexing technique. The absolute error and crosstalk are measured. An application to simultaneous two-parameter sensing is also demonstrated.
Guide to Geometric Algebra in Practice
Dorst, Leo
2011-01-01
This highly practical "Guide to Geometric Algebra in Practice" reviews algebraic techniques for geometrical problems in computer science and engineering, and the relationships between them. The topics covered range from powerful new theoretical developments, to successful applications, and the development of new software and hardware tools. This title: provides hands-on review exercises throughout the book, together with helpful chapter summaries; presents a concise introductory tutorial to conformal geometric algebra (CGA) in the appendices; examines the application of CGA for the d
Determination of the parameters of geometric configuration of scr ew reactor%螺杆反应器几何结构参数确定
Institute of Scientific and Technical Information of China (English)
司林旭; 郑安呐; 朱中南
2001-01-01
The calculation formulae on the parameters of geom etricconfiguration of single screw and closely intermeshing co-rotating twin- screw reactors were derived from the basic geometry, the process of closely inte rmeshing co-rotating of twin screws was described in detail, the calculation fo rmulae of the free volume, the area of cross section and the area of surface of twin-screw reactor were derived.%从基本几何学理论出发，推导了单螺杆和同向紧密啮合双螺杆反应器的几何结构参数计算式。对双螺杆的同向紧密啮合过程作了详细描述，导出了双螺杆反应器的空隙体积、横截面积和表面积计算式。
Wiswell, E. R.; Cooper, G. R. (Principal Investigator)
1978-01-01
The author has identified the following significant results. The concept of average mutual information in the received spectral random process about the spectral scene was developed. Techniques amenable to implementation on a digital computer were also developed to make the required average mutual information calculations. These techniques required identification of models for the spectral response process of scenes. Stochastic modeling techniques were adapted for use. These techniques were demonstrated on empirical data from wheat and vegetation scenes.
Geometric formula for prism deflection
Indian Academy of Sciences (India)
Apoorva G Wagh; Veer Chand Rakhecha
2004-08-01
While studying neutron deflections produced by a magnetic prism, we have stumbled upon a simple `geometric' formula. For a prism of refractive index close to unity, the deflection simply equals the product of the refractive power − 1 and the base-to-height ratio of the prism, regardless of the apex angle. The base and height of the prism are measured respectively along and perpendicular to the direction of beam propagation within the prism. The geometric formula greatly simplifies the optimisation of prism parameters to suit any specific experiment.
Geometrical description of denormalized thermodynamic manifold
Institute of Scientific and Technical Information of China (English)
Wu Li-Ping; Sun Hua-Fei; Cao Li-Mei
2009-01-01
In view of differential geometry,the state space of thermodynamic parameters is investigated. Here the geometrical structures of the denormalized thermodynamic manifold are considered. The relation of their geometrical metrics is obtained. Moreover an example is used to illustrate our conclusions.
Kahle, Matthew
2009-01-01
We study the expected topological properties of Cech and Vietoris-Rips complexes built on randomly sampled points in R^d. These are, in some cases, analogues of known results for connectivity and component counts for random geometric graphs. However, an important difference in this setting is that homology is not monotone in the underlying parameter. In the sparse range, we compute the expectation and variance of the Betti numbers, and establish Central Limit Theorems and concentration of measure. In the dense range, we introduce Morse theoretic arguments to bound the expectation of the Betti numbers, which is the main technical contribution of this article. These results provide a detailed probabilistic picture to compare with the topological statistics of point cloud data.
Directory of Open Access Journals (Sweden)
Olfa Bel Hadj Brahim Kechiche
2014-06-01
Full Text Available This study highlights the impact of an universal Phase Locked Loop (PLL parameters variation on PMSM position estimation at low speeds. Indeed, the PLL parameters variation impact on the PMSM rotor position estimation performance and robustness cannot be neglected anymore. For this purpose, the study presents the theory and simulation results of a demodulation scheme applied to Sensorless PMSM control based on the Pulsating Voltage Injection (PVI technique. Comprehensive simulations, carried out under MATLAB/SIMULINK®, are discussed according to the variation of the PLL proportional and integral parameters.
Directory of Open Access Journals (Sweden)
G.B. Camilo
2015-01-01
Full Text Available The aims of this study were to evaluate the forced oscillation technique (FOT and pulmonary densitovolumetry in acromegalic patients and to examine the correlations between these findings. In this cross-sectional study, 29 non-smoking acromegalic patients and 17 paired controls were subjected to the FOT and quantification of lung volume using multidetector computed tomography (Q-MDCT. Compared with the controls, the acromegalic patients had a higher value for resonance frequency [15.3 (10.9-19.7 vs 11.4 (9.05-17.6 Hz, P=0.023] and a lower value for mean reactance [0.32 (0.21-0.64 vs 0.49 (0.34-0.96 cm H2O/L/s2, P=0.005]. In inspiratory Q-MDCT, the acromegalic patients had higher percentages of total lung volume (TLV for nonaerated and poorly aerated areas [0.42% (0.30-0.51% vs 0.25% (0.20-0.32%, P=0.039 and 3.25% (2.48-3.46% vs 1.70% (1.45-2.15%, P=0.001, respectively]. Furthermore, the acromegalic patients had higher values for total lung mass in both inspiratory and expiratory Q-MDCT [821 (635-923 vs 696 (599-769 g, P=0.021 and 844 (650-945 vs 637 (536-736 g, P=0.009, respectively]. In inspiratory Q-MDCT, TLV showed significant correlations with all FOT parameters. The TLV of hyperaerated areas showed significant correlations with intercept resistance (rs=−0.602, P<0.001 and mean resistance (rs=−0.580, P<0.001. These data showed that acromegalic patients have increased amounts of lung tissue as well as nonaerated and poorly aerated areas. Functionally, there was a loss of homogeneity of the respiratory system. Moreover, there were correlations between the structural and functional findings of the respiratory system, consistent with the pathophysiology of the disease.
Camilo, G.B.; Carvalho, A.R.S.; Machado, D.C.; Mogami, R.; Kasuki, L.; Gadelha, M.R.; Melo, P.L.; Lopes, A.J.
2015-01-01
The aims of this study were to evaluate the forced oscillation technique (FOT) and pulmonary densitovolumetry in acromegalic patients and to examine the correlations between these findings. In this cross-sectional study, 29 non-smoking acromegalic patients and 17 paired controls were subjected to the FOT and quantification of lung volume using multidetector computed tomography (Q-MDCT). Compared with the controls, the acromegalic patients had a higher value for resonance frequency [15.3 (10.9-19.7) vs 11.4 (9.05-17.6) Hz, P=0.023] and a lower value for mean reactance [0.32 (0.21-0.64) vs 0.49 (0.34-0.96) cm H2O/L/s2, P=0.005]. In inspiratory Q-MDCT, the acromegalic patients had higher percentages of total lung volume (TLV) for nonaerated and poorly aerated areas [0.42% (0.30-0.51%) vs 0.25% (0.20-0.32%), P=0.039 and 3.25% (2.48-3.46%) vs 1.70% (1.45-2.15%), P=0.001, respectively]. Furthermore, the acromegalic patients had higher values for total lung mass in both inspiratory and expiratory Q-MDCT [821 (635-923) vs 696 (599-769) g, P=0.021 and 844 (650-945) vs 637 (536-736) g, P=0.009, respectively]. In inspiratory Q-MDCT, TLV showed significant correlations with all FOT parameters. The TLV of hyperaerated areas showed significant correlations with intercept resistance (rs=−0.602, P<0.001) and mean resistance (rs=−0.580, P<0.001). These data showed that acromegalic patients have increased amounts of lung tissue as well as nonaerated and poorly aerated areas. Functionally, there was a loss of homogeneity of the respiratory system. Moreover, there were correlations between the structural and functional findings of the respiratory system, consistent with the pathophysiology of the disease. PMID:26445330
Effect of '61-points relaxation technique' on stress parameters in premenstrual syndrome.
Dvivedi, Jyoti; Dvivedi, Sanjay; Mahajan, K K; Mittal, Sunita; Singhal, Anil
2008-01-01
Premenstrual Syndrome is a psychoneuroendocrine stress related disorder and more than 300 treatment modalities for PMS show that the existing remedies have not provided satisfactory help to relieve PMS. 61-points relaxation exercise (61-PR), a relatively less known hatha yoga technique, is a successful means of stress relaxation and is expected to relieve PMS as well. The present study was conducted on 50 clinically healthy women volunteers who were in their reproductive age group and in their premenstrual period, from which a control group (n = 20) and a PMS group (n = 30) based on the symptoms were identified. In both groups basal heart rate (HR/min), systolic (SBP; mmHg) and diastolic blood pressure (DBP; mmHg), electromyogram (EMG; mV), electrodermal galvanic activity (EDG; microv), respiratory rate (RR/min) and peripheral temperature (T; degrees F) were recorded and the subjects were taken through a guided 61-PR. The symptoms and parameters were re-recorded after the 61-PR. In control group, the basal HR was 82.06 +/- 8.07, SBP 111.95 +/- 8.23, DBP 76.8 +/- 6.42, EMG 4.08 +/- 2.99, EDG 9.77 +/- 3.29, RR 15.60 +/- 3.77 and T was 97.86 +/- 0.63. After 10 minutes of 61-PR, HR (77.27 +/-10.85, P 0.05) rose significantly. In the PMS group, the basal HR was 90.61 +/- 8.46, SBP 122.5 +/- 11.52, DBP 83.53 +/- 8.26, EMG 5.79 +/-2.75, EDG 13.14 +/- 6.54, RR 19.13 +/- 3.76 and T was 93.43 -/+ 5.29. After 10 minutes of 61-PR, HR (75.58 +/- 10.11, P relaxation. 61-PR is effective in providing relief from PMS and may be a useful adjuvant to medical therapy of PMS and other stress disorders.
Federal Laboratory Consortium — Purpose: The mission of the Geometric Design Laboratory (GDL) is to support the Office of Safety Research and Development in research related to the geometric design...
On Geometric Infinite Divisibility
Sandhya, E.; Pillai, R. N.
2014-01-01
The notion of geometric version of an infinitely divisible law is introduced. Concepts parallel to attraction and partial attraction are developed and studied in the setup of geometric summing of random variables.
Design of geometric phase measurement in EAST Tokamak
Lan, T; Liu, J; Jie, Y X; Wang, Y L; Gao, X; Qin, H
2016-01-01
The optimum scheme for geometric phase measurement in EAST Tokamak is proposed in this paper. The theoretical values of geometric phase for the probe beams of EAST Polarimeter-Interferometer (POINT) system are calculated by path integration in parameter space. Meanwhile, the influences of some controllable parameters on geometric phase are evaluated. The feasibility and challenge of distinguishing geometric effect in the POINT signal are also assessed in detail.
Chen, Chenglong; Ni, Jiangqun; Shen, Zhaoyi; Shi, Yun Qing
2017-06-01
Geometric transformations, such as resizing and rotation, are almost always needed when two or more images are spliced together to create convincing image forgeries. In recent years, researchers have developed many digital forensic techniques to identify these operations. Most previous works in this area focus on the analysis of images that have undergone single geometric transformations, e.g., resizing or rotation. In several recent works, researchers have addressed yet another practical and realistic situation: successive geometric transformations, e.g., repeated resizing, resizing-rotation, rotation-resizing, and repeated rotation. We will also concentrate on this topic in this paper. Specifically, we present an in-depth analysis in the frequency domain of the second-order statistics of the geometrically transformed images. We give an exact formulation of how the parameters of the first and second geometric transformations influence the appearance of periodic artifacts. The expected positions of characteristic resampling peaks are analytically derived. The theory developed here helps to address the gap left by previous works on this topic and is useful for image security and authentication, in particular, the forensics of geometric transformations in digital images. As an application of the developed theory, we present an effective method that allows one to distinguish between the aforementioned four different processing chains. The proposed method can further estimate all the geometric transformation parameters. This may provide useful clues for image forgery detection.
Comparison of Soft Computing Techniques for Modelling of the EDM Performance Parameters
Directory of Open Access Journals (Sweden)
M. V. Cakir
2013-01-01
Full Text Available Selection of appropriate operating conditions is an important attribute to pay attention for in electrical discharge machining (EDM of steel parts. The achievement of EDM process is affected by many input parameters; therefore, the computational relations between the output responses and controllable input parameters must be known. However, the proper selection of these parameters is a complex task and it is generally made with the help of sophisticated numerical models. This study investigates the capacity of Adaptive Nero-Fuzzy Inference System (ANFIS, genetic expression programming (GEP and artificial neural networks (ANN in the prediction of EDM performance parameters. The datasets used in modelling study were taken from experimental study. According to the results of estimating the parameters of all models in the comparison in terms of statistical performance is sufficient, but observed that ANFIS model is slightly better than the other models.
Jerszyński, Damian; Antosiak-Cyrak, Katarzyna; Habiera, Małgorzata; Wochna, Krystian; Rostkowska, Elżbieta
2013-01-01
The study aimed to examine changes in selected angular characteristics and duration of the stroke cycle in the back crawl and the front crawl in children learning to swim. Nine boys and two girls, aged 8-13 years, performed seven consecutive swimming tests. The children's movement technique was recorded with the use of three video cameras. The studied parameters included the angle of incidence between the trunk long axis and the waterline, elbow angle, shoulders roll, stroke cycle duration and stroke length. The results illustrate the development of swimming technique in youth swimmers. The results of the present study indicate the variability and phasing of learning of swimming technique by children.
Geometric Approaches to Quadratic Equations from Other Times and Places.
Allaire, Patricia R.; Bradley, Robert E.
2001-01-01
Focuses on geometric solutions of quadratic problems. Presents a collection of geometric techniques from ancient Babylonia, classical Greece, medieval Arabia, and early modern Europe to enhance the quadratic equation portion of an algebra course. (KHR)
Institute of Scientific and Technical Information of China (English)
杨雨豪
2012-01-01
The numerical simulation method is adopted as a research means in this paper to perform the calculation and analysis on the influence of the leading edge's assembled distance, length, angle and other geometrical parameters of the isolator forward wedge angle on the characteristic of isolator internal flow field. In comparison with the experiment results and verification results reportedd in the reference listed at the end of the paper, the numerical calculation method is more reliable and has higher discontinuous resolution. The research a-chieved the quantification effect law of different configuration conditions on maximum anti back pressures capability and total pressure loss coefficient of the isolator, and provided a basis for the further optimal design and experimental schemes of the isolator geometrical configuration.%该文以数值仿真方法为研究手段,计算分析了隔离段前向楔角前沿安装距离、楔角长度和角度等几何参数变化对隔离段内流场特征的影响.和文献中实验结果校验结果比较,该文采用的数值计算方法成熟可靠,具有较高的间断分辨率.研究同时获得了不同构型条件对隔离段的最大抗反压能力以及总压损失系数的量化影响规律,为隔离段几何构型的进一步优化设计和为实验方案的确定提供了依据.
Geometric Computing Based on Computerized Descriptive Geometric
Institute of Scientific and Technical Information of China (English)
YU Hai-yan; HE Yuan-Jun
2011-01-01
Computer-aided Design （CAD）, video games and other computer graphic related technology evolves substantial processing to geometric elements. A novel geometric computing method is proposed with the integration of descriptive geometry, math and computer algorithm. Firstly, geometric elements in general position are transformed to a special position in new coordinate system. Then a 3D problem is projected to new coordinate planes. Finally, according to 2D/3D correspondence principle in descriptive geometry, the solution is constructed computerized drawing process with ruler and compasses. In order to make this method a regular operation, a two-level pattern is established. Basic Layer is a set algebraic packaged function including about ten Primary Geometric Functions （PGF） and one projection transformation. In Application Layer, a proper coordinate is established and a sequence of PGFs is sought for to get the final results. Examples illustrate the advantages of our method on dimension reduction, regulatory and visual computing and robustness.
Hays, J. R.
1969-01-01
Lumped parametric system models are simplified and computationally advantageous in the frequency domain of linear systems. Nonlinear least squares computer program finds the least square best estimate for any number of parameters in an arbitrarily complicated model.
Zangiabadi, M.; H. R. MALEKI
2007-01-01
In the real-world optimization problems, coefficients of the objective function are not known precisely and can be interpreted as fuzzy numbers. In this paper we define the concepts of optimality for linear programming problems with fuzzy parameters based on those for multiobjective linear programming problems. Then by using the concept of comparison of fuzzy numbers, we transform a linear programming problem with fuzzy parameters to a multiobjective linear programming problem. To this end, w...
Ghadai, R. K.; Das, P. P.; Shivakoti, I.; Mondal, S. C.; Swain, B. P.
2017-07-01
Diamond-like carbon (DLC) coatings are widely used in medical, manufacturing and aerospace industries due to their excellent mechanical, biological, optical and tribological properties. The selection of optimal process parameters for efficient characteristics of DLC film is always a challenging issue for the materials science researchers. The optimal combination of the process parameters involved in the deposition of DLC films provide a better result, which subsequently help other researchers to choose the process parameters. In the present work Grey Relation Analysis (GRA) and Fuzzy-logic are being used for the optimization of process parameters in DLC film coating by using plasma assist chemical vapour deposition (PACVD) technique. The bias voltage, bias frequency, deposition pressure, gas composition are considered as input process parameters and hardness (GPa), Young's modulus (GPa), ratio between diamond to graphic fraction, (Id/Ig) ratio are considered as response parameters. The input parameters are optimized by grey fuzzy analysis. The contribution of individual input parameter is done by ANOVA. In this analysis found that bias voltage having the least influence and gas composition has highest influence in the PACVD deposited DLC films. The grey fuzzy analysis results indicated that optimum results for bias voltage, bias frequency, deposition pressure, gas composition for the DLC thin films are -50 V, 6 kHz, 4 μbar and 60:40 % respectively.
Distributed-parameter problem solved on a hybrid computer by a modified function storage technique
DEFF Research Database (Denmark)
Poulsen, N.J.
1969-01-01
Describes a method which is based on a function storage technique improved by a number of modifications; it fulfils the two main demands: the solution is based directly on the physical equations, and is accurate within 1%......Describes a method which is based on a function storage technique improved by a number of modifications; it fulfils the two main demands: the solution is based directly on the physical equations, and is accurate within 1%...
Jeykrishnan, J.; Vijaya Ramnath, B.; Akilesh, S.; Pradeep Kumar, R. P.
2016-09-01
In the field of manufacturing sectors, electric discharge machining (EDM) is widely used because of its unique machining characteristics and high meticulousness which can't be done by other traditional machines. The purpose of this paper is to analyse the optimum machining parameter, to curtail the machining time with respect to high material removal rate (MRR) and low tool wear rate (TWR) by varying the parameters like current, pulse on time (Ton) and pulse off time (Toff). By conducting several dry runs using Taguchi technique of L9 orthogonal array (OA), optimized parameters were found using analysis of variance (ANOVA) and the error percentage can be validated and parameter contribution for MRR and TWR were found.
Institute of Scientific and Technical Information of China (English)
李楠; 韩颖
2014-01-01
To deal with the weak signal strength in the measurement of capacitive proximity sensors, the effects of geometric parameter design were investigated,and the sensor measurement performance was greatly improved by the geometric parameter optimization. The comprehensive evaluation standards of sensor performance were presented, including penetration depth, signal strength and noise tolerance,measurement sensitivity and dynamic range. For round capacitive proximity sensors,the effects of the surface area on sensor performance were analyzed. Four different structures including rectangular,round,interdigital and spiral-shaped sensors were designed. In the same conditions,the electric field distributions of the sensors with four structures were simulated and the measured fringe capacitance was compared. The results indicate that the geometric parameters have remarkable influence on the measured signal strength and measurement sensitivity;comparing with rectangular and round sensors,the measurement sensitivity of interdigital and spiral-shaped sesnros was increased by 66 . 8% and 33 . 5%.%针对相邻电容传感器存在的测量信号微弱的问题，研究了相邻电容传感器的几何参数设计对传感器性能的具体影响，并通过几何参数的优化大幅度提高传感器测量性能．提出包括穿透深度、信号强度与噪声抑制、测量灵敏度与动态测量范围的相邻电容传感器性能综合评价细则．针对环形相邻电容传感器进行了极板几何面积变化对传感器性能影响的研究分析；设计了矩形、环形、交叉指形和螺旋盘形4种结构的相邻电容传感器，在等参数同测量环境下，对各相邻电容传感器分别进行电场仿真和边缘电容测量值比较，确定传感器几何形状对传感器性能的具体影响．实验结果表明，相邻电容传感器几何参数对传感器测量信号强度与测量灵敏度影响明显，复杂交叉指形与螺旋盘形的
Institute of Scientific and Technical Information of China (English)
A.K.LAKSHMINARAYANAN; V.BALASUBRAMANIAN
2008-01-01
Taguchi approach was applied to determine the most influential control factors which will yield better tensile strength of the joints of friction stir welded RDE-40 aluminium alloy. In order to evaluate the effect of process parameters such as tool rotational speed, traverse speed and axial force on tensile strength of friction stir welded RDE-40 aluminium alloy, Taguchi parametric design and optimization approach was used. Through the Taguchi parametric design approach, the optimum levels of process parameters were determined. The results indicate that the rotational speed, welding speed and axial force are the significant parameters in deciding the tensile strength of the joint. The predicted optimal value of tensile strength of friction stir welded RDE-40 aluminium alloy is 303 MPa. The results were confirmed by further experiments.
Nair, T R Gopalakrishnan
2011-01-01
The paper presents a method which shows a significant improvement in discovering the path over the distance vector protocol. The proposed method is a multi-parameter QoS along with the fitness function which shows that it overcomes the limitation of DV like routing loops by spanning tree approach, count-to-infinity problem by decision attribute. The input considered is a topology satisfying the QoS parameters of size 1 to 64 nodes and it was shown that an optimal path selection was obtained efficiently over the classical distance vector algorithm
Han, Kai-Feng; Zeng, Xin-Wu
2011-06-01
Based on the dual source cumulative rotation technique in the time-domain proposed by Zeng and MacBeth (1993), a new algebraic processing technique for extracting shear-wave splitting parameters from multi-component VSP data in frequency-dependent medium has been developed. By using this dual source cumulative rotation technique in the frequency-domain (DCTF), anisotropic parameters, including polarization direction of the shear-waves and timedelay between the fast and slow shear-waves, can be estimated for each frequency component in the frequency domain. It avoids the possible error which comes from using a narrow-band filter in the current commonly used method. By using synthetic seismograms, the feasibility and validity of the technique was tested and a comparison with the currently used method was also given. The results demonstrate that the shear-wave splitting parameters frequency dependence can be extracted directly from four-component seismic data using the DCTF. In the presence of larger scale fractures, substantial frequency dependence would be found in the seismic frequency range, which implies that dispersion would occur at seismic frequencies. Our study shows that shear-wave anisotropy decreases as frequency increases.
Institute of Scientific and Technical Information of China (English)
吴宝山
2007-01-01
A series of ITTC recommended procedures for Uncertainty Analysis in experimental fluid dynamic measurement were put into effect since 1999,but there are still a lot of details in UA application to be further discussed or revised by now. The topic in this paper is one of such details. Nondimensional formulae are usually used to express the measured hydrodynamic forces and moments in ship model test, so that various geometric parameters are involved in uncertainty analysis. Several examples are given to illustrate some confusion in the uncertainty analysis concerning the geometric parameters and,it is recommended that it is better to perform the uncertainty analysis based more on physical and engineering consideration than on mathematical formulae.%自从1992年ITTC-QS工作组致函ITTC技术委员会提请ITTC各成员单位依照ANSI/ASME PTC 19.1开展测量不确定度评定以来,不确定度分析一直是热门议题.AIAA于1999年发布了风洞试验不确定度分析的指南.ITTC从1999年起逐步发布了一系列关于船模试验不确定度分析的规程.在这些规程中,由模型加工误差引起的水动力系数不确定度分量一般是通过水动力系数的(无量纲)表达式进行分析计算的.这种分析,从数学上是合理的,但从物理上分析和依据工程判断,有些则是相当不合理的,甚至是分析中的一个误区.文章列举了若干实例对此进行了阐述,并提出:对于因水动力无量纲化而引入的几何参数,其不确定度影响分量不能简单地依据所采用的无量纲表达式进行分析评定,而是要基于水动力学的分析进行合理的评定.
DEFF Research Database (Denmark)
Kaniecki, M.; Saenz, E.; Rolo, L.;
2014-01-01
This paper demonstrates a method for material characterization (permittivity, permeability, loss tangent) based on the scattering parameters. The performance of the extraction algorithm will be shown for modelled and measured data. The measurements were carried out at the European Space Agency us...
DEFF Research Database (Denmark)
Mollerup, Mikkel; Hansen, Søren; Petersen, Carsten
2008-01-01
We combined an inverse routine for assessing the hydraulic soil parameters of the Campbell/Mualem model with the power series solution developed by Philip for describing one-dimensional vertical infiltration into a homogenous soil. We based the estimation routine on a proposed measurement procedure...
DEFF Research Database (Denmark)
Mollerup, Mikkel; Hansen, Søren; Petersen, Carsten
2008-01-01
We combined an inverse routine for assessing the hydraulic soil parameters of the Campbell/Mualem model with the power series solution developed by Philip for describing one-dimensional vertical infiltration into a homogenous soil. We based the estimation routine on a proposed measurement procedu...
Estimation of fracture parameters in foam core materials using thermal techniques
DEFF Research Database (Denmark)
Dulieu-Barton, J. M.; Berggreen, Christian; Boyenval Langlois, C.
2010-01-01
The paper presents some initial work on establishing the stress state at a crack tip in PVC foam material using a non-contact infra-red technique known as thermoelastic stress analysis (TSA). A parametric study of the factors that may affect the thermoelastic response of the foam material...... is described. A mode I simulated crack in the form of a machined notch is used to establish the feasibility of the TSA approach to derive stress intensity factors for the foam material. The overall goal is to demonstrate that thermal techniques have the ability to provide deeper insight into the behaviour...
Technique for Selecting Optimum Fan Compression Ratio based on the Effective Power Plant Parameters
Directory of Open Access Journals (Sweden)
I. I. Kondrashov
2016-01-01
Full Text Available Nowadays, civilian aircrafts occupy the major share of global aviation industry market. As to medium and long - haul aircrafts, turbofans with separate exhaust streams are widely used. Here, fuel efficiency is the main criterion of this engine. The paper presents the research results of the mutual influence of fan pressure ratio and bypass ratio on the effective specific fuel consumption. Shows the increasing bypass ratio to be a rational step for reducing the fuel consumption. Also considers the basic features of engines with a high bypass ratio. Among the other working process parameters, fan pressure ratio and bypass ratio are the most relevant for consideration as they are the most structural variables at a given level of technical excellence. The paper presents the dependence of the nacelle drag coefficient on the engine bypass ratio. For computation were adopted the projected parameters of prospective turbofans to be used in the power plant of the 180-seat medium-haul aircraft. Computation of the engine cycle was performed in Mathcad using these data, with fan pressure ratio and bypass ratio being varied. The combustion chamber gas temperature, the overall pressure ratio and engine thrust remained constant. Pressure loss coefficients, the efficiency of the engine components and the amount of air taken for cooling also remained constant. The optimal parameters corresponding to the minimum effective specific fuel consumption were found as the result of computation. The paper gives recommendations for adjusting optimal parameters, depending on the considered external factors, such as weight of engine and required fuel reserve. The obtained data can be used to estimate parameters of future turbofan engines with high bypass ratio.
Study on the Grey Polynomial Geometric Programming
Institute of Scientific and Technical Information of China (English)
LUODang
2005-01-01
In the model of geometric programming, values of parameters cannot be gotten owing to data fluctuation and incompletion. But reasonable bounds of these parameters can be attained. This is to say, parameters of this model can be regarded as interval grey numbers. When the model contains grey numbers, it is hard for common programming method to solve them. By combining the common programming model with the grey system theory,and using some analysis strategies, a model of grey polynomial geometric programming, a model of 8 positioned geometric programming and their quasi-optimum solution or optimum solution are put forward. At the same time, we also developed an algorithm for the problem.This approach brings a new way for the application research of geometric programming. An example at the end of this paper shows the rationality and feasibility of the algorithm.
Palanivelu, Sakthivel; Narasimha Rao, K. V.; Ramarathnam, Krishna Kumar
2015-12-01
In order to address various noise generation mechanisms and noise propagation phenomena of a tyre, it is necessary to study the tyre dynamic behaviour in terms of modal parameters. This paper enumerates a novel method of finding the modal parameters of a rolling tyre using an Explicit Finite Element Analysis and Operational Modal Analysis (OMA). ABAQUS Explicit, a commercial Finite Element (FE) software code has been used to simulate the experiment, a tyre rolling over a semi-circular straight and inclined cleat. The acceleration responses obtained from these simulations are used as input to the OMA. LMS test lab has been used for carrying out the Operational Modal Analysis. The modal results are compared with the published results of Kindt [22] and validated. Also, the modal results obtained from OMA are compared with FE modal results of stationary unloaded tyre, stationary loaded tyre and Steady State Transport rolling tyre.
Optimization of Cylindrical Grinding Process Parameters on C40E Steel Using Taguchi Technique
Directory of Open Access Journals (Sweden)
Naresh Kumar
2015-01-01
Full Text Available Surface finish and dimensional accuracy play a vital role in the today’s engineering industry. There are several methods used to achieve good surface finish like burnishing, honing and lapping, and grinding. Grinding is one of these ways that improves the surface finish and dimensional accuracy simultaneously. C40E steel has good industrial application in manufacturing of shafts, axles, spindles, studs, etc. In the present work the cylindrical grinding of C40E steel is done for the optimization of grinding process parameters. During this experimental work input process parameters i.e. speed, feed, depth of cut is optimized using Taguchi L9 orthogonal array. Analysis of variance (ANOVA concluded that surface roughness is minimum at the 210 rpm, 0.11mm/rev feed, and 0.04mm depth of penetration.
ℋ-matrix techniques for approximating large covariance matrices and estimating its parameters
Litvinenko, Alexander
2016-10-25
In this work the task is to use the available measurements to estimate unknown hyper-parameters (variance, smoothness parameter and covariance length) of the covariance function. We do it by maximizing the joint log-likelihood function. This is a non-convex and non-linear problem. To overcome cubic complexity in linear algebra, we approximate the discretised covariance function in the hierarchical (ℋ-) matrix format. The ℋ-matrix format has a log-linear computational cost and storage O(knlogn), where rank k is a small integer. On each iteration step of the optimization procedure the covariance matrix itself, its determinant and its Cholesky decomposition are recomputed within ℋ-matrix format. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)
Geometrization of Trace Formulas
Frenkel, Edward
2010-01-01
Following our joint work arXiv:1003.4578 with Robert Langlands, we make the first steps toward developing geometric methods for analyzing trace formulas in the case of the function field of a curve defined over a finite field. We also suggest a conjectural framework of geometric trace formulas for curves defined over the complex field, which exploits the categorical version of the geometric Langlands correspondence.
Localized Geometric Query Problems
Augustine, John; Maheshwari, Anil; Nandy, Subhas C; Roy, Sasanka; Sarvattomananda, Swami
2011-01-01
A new class of geometric query problems are studied in this paper. We are required to preprocess a set of geometric objects $P$ in the plane, so that for any arbitrary query point $q$, the largest circle that contains $q$ but does not contain any member of $P$, can be reported efficiently. The geometric sets that we consider are point sets and boundaries of simple polygons.
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Akimov Pavel Alekseevich
2012-10-01
Full Text Available The proposed paper covers the operator-related formulation of the eigenvalue problem of analysis of a three-dimensional structure that has piecewise-constant physical and geometrical parameters alongside the so-called basic direction within the framework of a discrete-continual approach (a discrete-continual finite element method, a discrete-continual variation method. Generally, discrete-continual formulations represent contemporary mathematical models that become available for computer implementation. They make it possible for a researcher to consider the boundary effects whenever particular components of the solution represent rapidly varying functions. Another feature of discrete-continual methods is the absence of any limitations imposed on lengths of structures. The three-dimensional problem of elasticity is used as the design model of a structure. In accordance with the so-called method of extended domain, the domain in question is embordered by an extended one of an arbitrary shape. At the stage of numerical implementation, relative key features of discrete-continual methods include convenient mathematical formulas, effective computational patterns and algorithms, simple data processing, etc. The authors present their formulation of the problem in question for an isotropic medium with allowance for supports restrained by elastic elements while standard boundary conditions are also taken into consideration.
Hristov, Dimitre H; Moftah, Belal A; Charrois, Colette; Parker, William; Souhami, Luis; Podgorsak, Ervin B
2002-01-01
The influence of organ volume sampling, lateral scatter inclusion, and the selection of objectives and constraints on the inverse treatment planning process with a commercial treatment planning system is investigated and suitable parameters are identified for an inverse treatment planning replacement of a clinical forward planning technique for prostate cancer. For the beam geometries of the forward technique, a variable set of parameters is used for the calculation of dose from pencil beams. An optimal set is identified after the evaluation of optimized plans that correspond to different sets of pencil-beam parameters. This set along with a single, optimized set of objectives and constraints is used to perform inverse planning on ten randomly selected patients. The acceptability of the resulting plans is verified by comparisons to the clinical ones calculated with the forward techniques. For the particular commercial treatment planning system, the default values of the pencil beam parameters are found adequate for inverse treatment planning. For all ten patients, the optimized, single set of objectives and constraints results in plans with target coverage comparable to that of the forward plans. Furthermore inverse treatment planning reduces the overall mean rectal and bladder doses by 4.8% and 5.8% of the prescription dose respectively. The study indicates that (i) inverse treatment planning results depend implicitly on the sampling of the dose distribution, (ii) inverse treatment planning results depend on the method used by the dose calculation model to account for scatter, and (iii) for certain sites, a single set of optimization parameters can be used for all patient plans.
Recovery of material parameters of soft hyperelastic tissue by an inverse spectral technique
Gou, Kun
2012-07-01
An inverse spectral method is developed for recovering a spatially inhomogeneous shear modulus for soft tissue. The study is motivated by a novel use of the intravascular ultrasound technique to image arteries. The arterial wall is idealized as a nonlinear isotropic cylindrical hyperelastic body. A boundary value problem is formulated for the response of the arterial wall within a specific class of quasistatic deformations reflective of the response due to imposed blood pressure. Subsequently, a boundary value problem is developed via an asymptotic construction modeling intravascular ultrasound interrogation which generates small amplitude, high frequency time harmonic vibrations superimposed on the static finite deformation. This leads to a system of second order ordinary Sturm-Liouville boundary value problems that are then employed to reconstruct the shear modulus through a nonlinear inverse spectral technique. Numerical examples are demonstrated to show the viability of the method. © 2012 Elsevier Ltd. All rights reserved.
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Xiaojing Wu
2017-01-01
Full Text Available Airfoil geometric uncertainty can generate aerodynamic characteristics fluctuations. Uncertainty quantification is applied to compute its impact on the aerodynamic characteristics. In addition, the contribution of each uncertainty variable to aerodynamic characteristics should be computed by the uncertainty sensitivity analysis. In the paper, Sobol’s analysis is used for uncertainty sensitivity analysis and a nonintrusive polynomial chaos method is used for uncertainty quantification and Sobol’s analysis. It is difficult to describe geometric uncertainty because it needs a lot of input parameters. In order to alleviate the contradiction between the variable dimension and computational cost, a principal component analysis is introduced to describe geometric uncertainty of airfoil. Through this technique, the number of input uncertainty variables can be reduced and typical global deformation modes can be obtained. By uncertainty quantification, we can learn that the flow characteristics of shock wave and boundary layer separation are sensitive to the geometric uncertainty in transonic region, which is the main reason that transonic drag is sensitive to the geometric uncertainty. The sensitivity analysis shows that the model can be simplified by eliminating unimportant geometric modes. Moreover, which are the most important geometric modes to transonic aerodynamics can be learnt. This is very helpful for airfoil design.
Cross, J. L.; Stevens, D. D.
1976-01-01
A computerized study of operational parameters affecting helicopter fuel consumption was conducted as an integral part of the NASA Civil Helicopter Technology Program. The study utilized the Helicopter Sizing and Performance Computer Program (HESCOMP) developed by the Boeing-Vertol Company and NASA Ames Research Center. An introduction to HESCOMP is incorporated in this report. The results presented were calculated using the NASA CH-53 civil helicopter research aircraft specifications. Plots from which optimum flight conditions for minimum fuel use that can be obtained are presented for this aircraft. The results of the study are considered to be generally indicative of trends for all helicopters.
The Analysis of the Structural Parameters of Magnetic Fluids with SAXS and MGA Techniques
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P.A. Ryapolov
2015-12-01
Full Text Available Purpose – to study the structural parameters of the magnetite particles surrounded by the surfactant in the various carrier liquids using SAXS and based on the magnetization curve obtained applying ballistic method. The samples of the magnetite magnetic fluid based on water, engine oil and kerosene were investigated in this paper. Methodology – three samples of magnetic fluid were chosen for studying. Samples No 1 and No 2 were obtained at the UNESCO department of “Energy Conservation and Renewable Energy Sources”, Belarusian National Technical University. Sample No 3 was obtained in the Fundamental Scientific Research Laboratory of Applied Ferrohydrodynamics of Ivanovo State Power Engineering University. SAXS experiment was conducted using Anton Paar SAXSess mc2 analyzer at the Regional Centre of Nanotechnology of Southwest State University. Originality / value – The value of this work is to obtain new data on the physical parameters of the magnetic fluid samples. Findings – the derived surfactant shell width, which for the samples No 2, 3 was 1,8-1,9 nm, for the sample No 1 surfactant shell width was 3.5 nm, the excess of the calculated width of the surfactant layer can be explained due to the presence of a double layer of stabilizer.
Role of priming technique in germination parameters of calendula (Calendula officinalis L. seeds
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Karimi Mahnaz
2016-01-01
Full Text Available Seed priming is known for its promoting effects on seed and seedling properties under stress conditions such as salinity, temperature and drought stresses. Poor plant stand establishment is a common problem for marigold production. Therefore, an experiment was conducted to investigate the effect of different seed priming techniques on calendula seed germination and seedling enzyme activity. For this purpose, different seed priming techniques: hydropriming (distilled water, 24 and 72 h, osmopriming (0.02% or 0.04% KNO3 for 24 and 72 h and hormonal priming (100 or 500 mg L-1 GA3 for 24 and 72 h were assessed. Seeds without any treatment were considered as control. Compared with control, 100 mg L-1 GA3 and distilled water for 72 h showed the highest promoting effects on germination percentage. The highest vigor index (525.75 was related to hydropriming (for 24 h treatment. Also, the maximum root length was found with 0.02% KNO3 for 72 h. Catalase significantly increased in the primed seeds. The highest CAT activity and total soluble sugars were found in the seeds primed with 100 mg L-1 GA3 for 72 h. Moreover, the enzyme activity was significantly higher in the distilled water and KNO3 treatments compared with the untreated seeds.
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F. Bernauer
2015-03-01
Full Text Available Detailed characterization and classification of precipitation is an important task in atmospheric research. Line scanning 2-D-video disdrometer technique is well established for rain observations. The two orthogonal views taken of each hydrometeor passing the sensitive area of the instrument qualify this technique especially for detailed characterization of non symmetric solid hydrometeors. However, in case of solid precipitation problems related to the matching algorithm have to be considered and the user must be aware of the limited spacial resolution when size and shape descriptors are analyzed. This work has the aim of clarifying the potential of 2-D-video disdrometer technique in deriving size, velocity and shape parameters from single recorded pictures. The need of implementing a matching algorithm suitable for mixed and solid phase precipitation is highlighted as an essential step in data evaluation. For this purpose simple reproducible experiments with solid steel spheres and irregularly shaped styrofoam particles are conducted. Self-consistency of shape parameter measurements is tested in 40 cases of real snow fall. As result it was found, that reliable size and shape characterization with a relative standard deviation of less than 5% is only possible for particles larger than 1 mm. For particles between 0.5 and 1.0 mm the relative standard deviation can grow up to 22% for the volume, 17% for size parameters and 14% for shape descriptors. Testing the adapted matching algorithm with a reproducible experiment with styrofoam particles a mismatch probability of less than 2.5% was found. For shape parameter measurements in case of real solid phase precipitation the 2DVD shows self-consistent behavior.
Early shell crack detection technique using acoustic emission energy parameter blast furnaces
Energy Technology Data Exchange (ETDEWEB)
Kim, Dong Hyun; Lee, Sang Bum [RECTUSON Co.,Ltd., Changwon (Korea, Republic of); Bae, Dong Myung; Yang, Bo Suk [Pukyong National University, Busan (Korea, Republic of)
2016-02-15
Blast furnaces are crucial equipment for steel production. A typical furnace risks unexpected accidents caused by contraction and expansion of the walls under an environment of high temperature and pressure. In this study, an acoustic emission (AE) monitoring system was tested for evaluating the large-scale structural health of a blast furnace. Based on the growth of shell cracks with the emission of high energy levels, severe damage can be detected by monitoring increases in the AE energy parameter. Using this monitoring system, steel mill operators can establish a maintenance period, in which actual shell cracks can be verified by cross-checking the UT. From this study, we expect that AE systems permit early fault detection for structural health monitoring by establishing evaluation criteria based on the severity of shell cracking.
Developing Dynamic Digital Image Techniques with Continuous Parameters to Detect Structural Damage
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Ming-Hsiang Shih
2013-01-01
Full Text Available Several earthquakes with strong magnitude occurred globally at various locations, especially the unforgettable tsunami disaster caused by the earthquake in Indonesia and Japan. If the characteristics of structures can be well understood to implement new technology, the damages caused by most natural disasters can be significantly alleviated. In this research, dynamic digital image correlation method for using continuous parameter is applied for developing a low-cost digital image correlation coefficient method with advanced digital cameras and high-speed computers. The experimental study using cantilever test object with defect control confirms that the vibration mode calculated using this proposed method can highly express the defect locations. This proposed method combined with the sensitivity of Inter-Story Drift Mode Shape, IDMS, can also reveal the damage degree of damage structure. These test and analysis results indicate that this proposed method is high enough for applying to achieve the object of real-time online monitoring of structure.
Exploring New Geometric Worlds
Nirode, Wayne
2015-01-01
When students work with a non-Euclidean distance formula, geometric objects such as circles and segment bisectors can look very different from their Euclidean counterparts. Students and even teachers can experience the thrill of creative discovery when investigating these differences among geometric worlds. In this article, the author describes a…
Gorges, Sébastien; Kerrien, Erwan; Berger, Marie-Odile; Trousset, Yves; Pescatore, Jérémie; Anxionnat, René; Picard, Luc
2006-03-01
The real time recovery of the projection geometry is a fundamental issue in interventional navigation applications (e.g. guide wire reconstruction, medical augmented reality). In most works, the intrinsic parameters are supposed to be constant and the extrinsic parameters (C-arm motion) are deduced either from the orientation sensors of the C-arm or from other additional sensors (eg. optical and/or electro-magnetic sensors). However, due to the weight of the X-ray tube and the C-arm, the system is undergoing deformations which induce variations of the intrinsic parameters as a function of the C-arm orientation. In our approach, we propose to measure the effects of the mechanical deformations onto the intrinsic parameters in a calibration procedure. Robust calibration methods exist (the gold standard is the multi-image calibration) but they are time consuming and too tedious to set up in a clinical context. For these reasons, we developed an original and easy to use method, based on a planar calibration target, which aims at measuring with a high level of accuracy the variation of the intrinsic parameters on a vascular C-arm. The precision of the planar-based method was evaluated by the mean of error propagation using techniques described in. 8 It appeared that the precision of the intrinsic parameters are comparable to the one obtained from the multi-image calibration method. The planar-based method was also successfully used to assess to behavior of the C-arm with respect to the C-arm orientations. Results showed a clear variation of the principal point when the LAO/RAO orientation was changed. In contrast, the intrinsic parameters do not change during a cranio-caudal C-arm motion.
Non-overlapped random decrement technique for parameter identification in operational modal analysis
Zhang, Y.; Song, H. W.
2016-03-01
The random decrement technique (RDT) is used to estimate free vibration response from output data generated by Gaussian white noise. The principle is to decay the excitation via averaging of segments in output data. With RDT, the triggering condition for determining the initial points of segments causes overlap during averaging; the consequence is a residual excitation, peaking at the first natural frequency. This paper presents a modified RDT with non-overlapped segments to eliminate this peak. Numerical comparison between non-overlapped RDT (NRDT) and RDT shows the accuracy improvement of damping. However, time history data is sometimes not long enough in NRDT, which results in an inevitable overlap. In order to keep the accuracy of NRDT, the first natural period is viewed as the critical length between adjacent initial points to distinguish the inevitable overlap from that in RDT.
A field technique for estimating aquifer parameters using flow log data
Paillet, Frederick L.
2000-01-01
A numerical model is used to predict flow along intervals between producing zones in open boreholes for comparison with measurements of borehole flow. The model gives flow under quasi-steady conditions as a function of the transmissivity and hydraulic head in an arbitrary number of zones communicating with each other along open boreholes. The theory shows that the amount of inflow to or outflow from the borehole under any one flow condition may not indicate relative zone transmissivity. A unique inversion for both hydraulic-head and transmissivity values is possible if flow is measured under two different conditions such as ambient and quasi-steady pumping, and if the difference in open-borehole water level between the two flow conditions is measured. The technique is shown to give useful estimates of water levels and transmissivities of two or more water-producing zones intersecting a single interval of open borehole under typical field conditions. Although the modeling technique involves some approximation, the principle limit on the accuracy of the method under field conditions is the measurement error in the flow log data. Flow measurements and pumping conditions are usually adjusted so that transmissivity estimates are most accurate for the most transmissive zones, and relative measurement error is proportionately larger for less transmissive zones. The most effective general application of the borehole-flow model results when the data are fit to models that systematically include more production zones of progressively smaller transmissivity values until model results show that all accuracy in the data set is exhausted.A numerical model is used to predict flow along intervals between producing zones in open boreholes for comparison with measurements of borehole flow. The model gives flow under quasi-steady conditions as a function of the transmissivity and hydraulic head in an arbitrary number of zones communicating with each other along open boreholes. The
Geometric phases in discrete dynamical systems
Energy Technology Data Exchange (ETDEWEB)
Cartwright, Julyan H.E., E-mail: julyan.cartwright@csic.es [Instituto Andaluz de Ciencias de la Tierra, CSIC–Universidad de Granada, E-18100 Armilla, Granada (Spain); Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, E-18071 Granada (Spain); Piro, Nicolas, E-mail: nicolas.piro@epfl.ch [École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne (Switzerland); Piro, Oreste, E-mail: piro@imedea.uib-csic.es [Departamento de Física, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain); Tuval, Idan, E-mail: ituval@imedea.uib-csic.es [Mediterranean Institute for Advanced Studies, CSIC–Universitat de les Illes Balears, E-07190 Mallorca (Spain)
2016-10-14
In order to study the behaviour of discrete dynamical systems under adiabatic cyclic variations of their parameters, we consider discrete versions of adiabatically-rotated rotators. Parallelling the studies in continuous systems, we generalize the concept of geometric phase to discrete dynamics and investigate its presence in these rotators. For the rotated sine circle map, we demonstrate an analytical relationship between the geometric phase and the rotation number of the system. For the discrete version of the rotated rotator considered by Berry, the rotated standard map, we further explore this connection as well as the role of the geometric phase at the onset of chaos. Further into the chaotic regime, we show that the geometric phase is also related to the diffusive behaviour of the dynamical variables and the Lyapunov exponent. - Highlights: • We extend the concept of geometric phase to maps. • For the rotated sine circle map, we demonstrate an analytical relationship between the geometric phase and the rotation number. • For the rotated standard map, we explore the role of the geometric phase at the onset of chaos. • We show that the geometric phase is related to the diffusive behaviour of the dynamical variables and the Lyapunov exponent.
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Joe Pitt-Francis
2006-01-01
Full Text Available A vast array of mathematical models have been proposed for all stages of cancer formation across a wide range of spatio–temporal scales. Attention is now turning to coupling these models across scales and building models of “virtual tumours” for use in in silico testing of novel drugs and treatment regimes. This leads naturally to the requirement for detailed knowledge of the underlying geometry and physiological properties of individual tumours for use in: (i multi-scale mathematical models of in vivo tumour growth and development; (ii fusion of multi-scale, multimodal medical imaging techniques to improve the diagnosis and treatment of individual patients; and (iii training of cancer specialists and surgeons.
Geometric Transformations in Engineering Geometry
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I. F. Borovikov
2015-01-01
Full Text Available Recently, for business purposes, in view of current trends and world experience in training engineers, research and faculty staff there has been a need to transform traditional courses of descriptive geometry into the course of engineering geometry in which the geometrical transformations have to become its main section. On the basis of critical analysis the paper gives suggestions to improve a presentation technique of this section both in the classroom and in academic literature, extend an application scope of geometrical transformations to solve the position and metric tasks and simulation of surfaces, as well as to design complex engineering configurations, which meet a number of pre-specified conditions.The article offers to make a number of considerable amendments to the terms and definitions used in the existing courses of descriptive geometry. It draws some conclusions and makes the appropriate proposals on feasibility of coordination in teaching the movement transformation in the courses of analytical and descriptive geometry. This will provide interdisciplinary team teaching and allow students to be convinced that a combination of analytical and graphic ways to solve geometric tasks is useful and reasonable.The traditional sections of learning courses need to be added with a theory of projective and bi-rational transformations. In terms of application simplicity and convenience it is enough to consider the central transformations when solving the applied tasks. These transformations contain a beam of sub-invariant (low-invariant straight lines on which the invariant curve induces non-involution and involution projectivities. The expediency of nonlinear transformations application is shown in the article by a specific example of geometric modeling of the interfacing surface "spar-blade".Implementation of these suggestions will contribute to a real transformation of a traditional course of descriptive geometry to the engineering geometry
Muravsky, Leonid I.; Picart, Pascal; Kmet', Arkady B.; Voronyak, Taras I.; Ostash, Orest P.; Stasyshyn, Ihor V.
2016-08-01
A new two-step phase shifting interferometry technique for evaluation of a fatigue process zone (FPZ) in notched metal and alloy specimens is proposed. In comparison with well-known destructive and nondestructive methods evaluating FPZ, this technique possesses higher accuracy and performance and allows defining the FPZ size for notched specimens made of metals and alloys with low, moderate or high plasticity. The technique is fulfilled by retrieval of a total surface relief of a studied notched specimen, extraction of surface roughness and waviness phase maps from the retrieved surface relief, calculation of a surface roughness parameter Ra spatial distribution and definition of the FPZ size by using an extracted surface roughness phase map. Obtained experimental results have confirmed assumption that the surface roughness of notched specimens after cyclic loading reaches its maximum values at the FPZ boundary. This boundary is produced as the narrow strip containing pixels possessing the maximum values on the spatial distribution of the roughness parameter Ra near a notch root. The basic distances d* defining the FPZ sizes were measured for notched specimens made of a low-carbon steel and aluminum alloys 2024-T6 and 7075-T3. Results of the distances d* measurement are very close to respective results obtained with the help of other methods for the FPZ evaluation.
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Z. Pasandidehfard
2014-03-01
Full Text Available Nonpoint source (NPS pollution is a major surface water contaminant commonly caused by agricultural runoff. The purpose of this study was to assess seasonal variation in water quality parameters in Gorganrood watershed (Golestan Province, Iran. It also tried to clarify the effects of agricultural practices and NPS pollution on them. Water quality parameters including potassium, sodium, pH, water flow rate, total dissolved solids (TDS, electrical conductivity (EC, hardness, sulfate, bicarbonate, chlorine, magnesium, and calcium ions during 1966-2010 were evaluated using multivariate statistical techniques. Multivariate analysis of variance (MANOVA was implemented to determine the significance of differences between mean seasonal values. Discriminant analysis (DA was also carried out to identify correlations between seasons and the water quality parameters. Parameters of water quality index were measured through principal component analysis (PCA and factor analysis (FA. Based on the results of statistical tests, climate (freezing, weathering and rainfall and human activities such as agriculture had crucial effects on water quality. The most important parameters in differentiation between seasons in descending order were potassium, pH, carbonic acid, calcium, and magnesium. According to load factor analysis, chlorine, calcium, and potassium were the most important parameters in spring and summer, indicating the application of fertilizers (especially potassium chloride fertilizer and existence of NPS pollution during these seasons. In the next stage, the months during which crops had excessive water requirements were detected using CROPWAT software. Almost all water requirements of the area’s major crops, i.e. cotton, rice, soya, wheat, and oat, happen in the late spring until mid/late summer. According to our findings, agricultural practices had a great impact on water pollution. Results of analysis with CROPWAT software also confirmed this
Institute of Scientific and Technical Information of China (English)
王荣娟; 雷玉勇; 蒋代君; 戴良博; 卫排锋
2011-01-01
Based on the physic model of water jet cutting head, the two-dimensional mathematical model of flow field inside the cutting head was built using turbulent jet basic equation.The internal flow field of focusing tube was simulated using standard k-ε turbulence model based on FLUENT.The influence of the geometric parameters of focusing tube on distribution of water jet velocity field was researched.The results show that the contraction angle α, the ratio of length and diameter l/d, as well as the outlet diameter d of the focusing tube have a significant effects on the internal velocity field of water jet.When α = 20°, l/d = 70, the outlet jet velocity of the focusing tube is maximum.%基于水射流切割头的物理模型,根据湍流射流的基本方程建立了喷头内部流场的二维数学模型.采用标准k-ε湍流模型并应用FLUENT软件对聚焦管内部流场进行数值模拟,研究聚焦管几何参数对纯水射流速度流场的影响.研究结果表明:聚焦管人口收缩角α、长径比l/d和出口直径d对聚焦管内部速度流场有显著影响,当α=20°、l/d=70时,聚焦管出口射流速度最大.
Ratke, L.; Sharma, A.; Kohli, D.
2012-01-01
Rapid slurry formation is a semi-solid metal forming technique, which is based on a so-called solid enthalpy exchange material (EEM). It is a fascinating technology offering the opportunity to manufacture net-shaped metal components of complex geometry in a single forming operation. At the same time, high mechanical properties can be achieved due to the unique microstructure and flow behaviour. The major process parameters used in the RSF process are rotation speed of the EEM, melt superheat, amount of EEM added (determining fs), and holding time. The process parameters can be well controlled with clear effects on the microstructure. There is a lack of theoretical modelling of the morphological evolution in these two-phase slurries.
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Lotfy Y. A.
2006-07-01
Full Text Available Polyally diglycol carbonate "CR-39" is widely used as etched track type particle detector. Doppler broadening positron annihilation (DBPAT provides direct information about core and valance electrons in (CR-39 due to radiation effects. It provides a non-destructive and non-interfering probe having a detecting efficiency. This paper reports the effect of irradiation alpha-particle intensity emitted from 241-Am (5.486 MeV source on the line shape S- and W-parameters for CR-39 samples. Modification of the CR-39 samples due to irradiation were studied using X-ray diffraction (XRD and scanning electron microscopy (SEM techniques.
Satellite orientation and position for geometric correction of scanner imagery.
Salamonowicz, P.H.
1986-01-01
The USGS Mini Image Processing System currently relies on a polynomial method for geometric correction of Landsat multispectral scanner (MSS) data. A large number of ground control points are required because polynomials do not model the sources of error. In order to reduce the number of necessary points, a set of mathematical equations modeling the Landsat satellite motions and MSS scanner has been derived and programmed. A best fit to the equations is obtained by using a least-squares technique that permits computation of the satellite orientation and position parameters based on only a few control points.-from Author
Retrieval of Geophysical Parameters from GOES: Evaluation of a Split-Window Technique.
Suggs, Ronnie J.; Jedlovec, Gary J.; Guillory, Anthony R.
1998-10-01
imager ST retrieval errors, which were about half of the VAS values, ranged from about 0.2 to 0.6 K, exhibiting little diurnal effect. The PW retrieval errors ranged from about 2.0 to 7.0 mm with a modest sensitivity to the different sensor channels. However, a significant diurnal trend in the PW retrieval errors that correlated with the presence of surface- and low-level temperature inversions was observed. The algorithm performance results provide insight into the application of GOES split-window retrieval methodologies for climate variability studies and may have implications for operational applications of similar retrieval techniques.
González-Marcos, A.; Sarro, L. M.; Ordieres-Meré, J.; Bello-García, A.
2017-03-01
The determination of stellar atmospheric parameters from spectra suffers the so-called curse-of-dimensionality problem, which is related to the higher number of input variables (flux values) compared to the number of spectra available to fit a regression model (this collection of examples is known as the training set). This work evaluates the utility of several techniques for alleviating this problem in regression tasks where the objective is to estimate the effective temperature (Teff), the surface gravity (log g), the metallicity ([M/H]) and/or the alpha-to-iron ratio ([α/Fe]). The goal of the techniques analysed here is to achieve data compression by representing the spectra with a number of variables much lower than the initially available set of fluxes. The experiments were performed with high-resolution spectra of stars in the 4000-8000 K range for different signal-to-noise ratio (SNR) regimes. We conclude that independent component analysis (ICA) performs better than the rest of techniques evaluated for all SNR regimes. We also assess the necessity to adapt the SNR of the spectra used to fit a regression model (training set) to the SNR of the spectra for which the atmospheric parameters are needed (evaluation set). Within the conditions of our experiments, we conclude that at most only two such regression models are needed (in the case of regression models for effective temperatures, those corresponding to SNR = 50 and 10) to cover the entire SNR range. Finally, we also compare the prediction accuracy of effective temperature regression models for increasing values of the training grid density and the same compression techniques.
Geometric and unipotent crystals
Berenstein, Arkady; Kazhdan, David
1999-01-01
In this paper we introduce geometric crystals and unipotent crystals which are algebro-geometric analogues of Kashiwara's crystal bases. Given a reductive group G, let I be the set of vertices of the Dynkin diagram of G and T be the maximal torus of G. The structure of a geometric G-crystal on an algebraic variety X consists of a rational morphism \\gamma:X-->T and a compatible family e_i:G_m\\times X-->X, i\\in I of rational actions of the multiplicative group G_m satisfying certain braid-like ...
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Hwa Kian Chai
2016-04-01
Full Text Available Concrete is the most ubiquitous construction material. Apart from the fresh and early age properties of concrete material, its condition during the structure life span affects the overall structural performance. Therefore, development of techniques such as non-destructive testing which enable the investigation of the material condition, are in great demand. Tomography technique has become an increasingly popular non-destructive evaluation technique for civil engineers to assess the condition of concrete structures. In the present study, this technique is investigated by developing reconstruction procedures utilizing different parameters of elastic waves, namely the travel time, wave amplitude, wave frequency, and Q-value. In the development of algorithms, a ray tracing feature was adopted to take into account the actual non-linear propagation of elastic waves in concrete containing defects. Numerical simulation accompanied by experimental verifications of wave motion were conducted to obtain wave propagation profiles in concrete containing honeycomb as a defect and in assessing the tendon duct filling of pre-stressed concrete (PC elements. The detection of defects by the developed tomography reconstruction procedures was evaluated and discussed.
Geometric Properties of AR（q） Nonlinear Regression Models
Institute of Scientific and Technical Information of China (English)
LIUYing-ar; WEIBo-cheng
2004-01-01
This paper is devoted to a study of geometric properties of AR(q) nonlinear regression models. We present geometric frameworks for regression parameter space and autoregression parameter space respectively based on the weighted inner product by fisher information matrix. Several geometric properties related to statistical curvatures are given for the models. The results of this paper extended the work of Bates & Watts(1980,1988)[1.2] and Seber & Wild (1989)[3].
D Image Based Geometric Documentation of the Tower of Winds
Tryfona, M. S.; Georgopoulos, A.
2016-06-01
This paper describes and investigates the implementation of almost entirely image based contemporary techniques for the three dimensional geometric documentation of the Tower of the Winds in Athens, which is a unique and very special monument of the Roman era. These techniques and related algorithms were implemented using a well-known piece of commercial software with extreme caution in the selection of the various parameters. Problems related to data acquisition and processing, but also to the algorithms and to the software implementation are identified and discussed. The resulting point cloud has been georeferenced, i.e. referenced to a local Cartesian coordinate system through minimum geodetic measurements, and subsequently the surface, i.e. the mesh was created and finally the three dimensional textured model was produced. In this way, the geometric documentation drawings, i.e. the horizontal section plans, the vertical section plans and the elevations, which include orthophotos of the monument, can be produced at will from that 3D model, for the complete geometric documentation. Finally, a 3D tour of the Tower of the Winds has also been created for a more integrated view of the monument. The results are presented and are evaluated for their completeness, efficiency, accuracy and ease of production.
Multi-technique comparison of atmospheric parameters at the DORIS co-location sites during CONT14
Heinkelmann, Robert; Willis, Pascal; Deng, Zhiguo; Dick, Galina; Nilsson, Tobias; Soja, Benedikt; Zus, Florian; Wickert, Jens; Schuh, Harald
2016-12-01
The atmospheric parameters, zenith delays and gradients, obtained by the DORIS, GPS, VLBI, and numerical weather models, ECMWF and NCEP, are compared at five DORIS co-located sites during the 15 days of the CONT14 campaign from 2014-05-06 until 2014-05-20. Further examined are two different solutions of GPS, VLBI and NCEP: for GPS, a network solution comparable to the TIGA reprocessing analysis strategy and a precise point positioning solution, for VLBI, a least squares and a Kalman filtered and smoothed solution, and for NCEP two spatial resolutions, 0.5° and 1.0°, are tested. The different positions of the antenna reference points at co-location sites affect the atmospheric parameters and have to be considered prior to the comparison. We assess and discuss these differences, tropospheric ties, by comparing ray-traced atmospheric parameters obtained at the positions of the various antenna reference points. While ray-traced ZHD and ZWD at the co-located antennas significantly differ, the ray-traced gradients show only very small differences. Weather events can introduce larger disagreement between atmospheric parameters obtained at co-location sites. The various weather model solutions in general agree very well in providing tropospheric ties. The atmospheric parameters are compared using statistical methods, such as the mean difference and standard deviations with repect to a weighted mean value. While GPS and VLBI atmospheric parameters agree very well in general, the DORIS observations are in several cases not dense enough to achieve a comparable level of agreement. The estimated zenith delays from DORIS, however, are competitive with the other space geodetic techniques. If the DORIS observation geometry is insufficient for the estimation of an atmospheric gradient, less than three satellites observed during the definition interval, the DORIS atmospheric parameters degrade and show small quasi-periodic variations that correlate with the number of observations
Geometric and engineering drawing
Morling, K
2010-01-01
The new edition of this successful text describes all the geometric instructions and engineering drawing information that are likely to be needed by anyone preparing or interpreting drawings or designs with plenty of exercises to practice these principles.
Differential geometric structures
Poor, Walter A
2007-01-01
This introductory text defines geometric structure by specifying parallel transport in an appropriate fiber bundle and focusing on simplest cases of linear parallel transport in a vector bundle. 1981 edition.
Bledsoe, Gloria J
1987-01-01
The game of "Guess What" is described as a stimulating vehicle for students to consider the unifying or distinguishing features of geometric figures. Teaching suggestions as well as the gameboard are provided. (MNS)
Saturation and geometrical scaling
Praszalowicz, Michal
2016-01-01
We discuss emergence of geometrical scaling as a consequence of the nonlinear evolution equations of QCD, which generate a new dynamical scale, known as the saturation momentum: Qs. In the kinematical region where no other energy scales exist, particle spectra exhibit geometrical scaling (GS), i.e. they depend on the ratio pT=Qs, and the energy dependence enters solely through the energy dependence of the saturation momentum. We confront the hypothesis of GS in different systems with experimental data.
Geometrical Phases in Quantum Mechanics
Christian, Joy Julius
In quantum mechanics, the path-dependent geometrical phase associated with a physical system, over and above the familiar dynamical phase, was initially discovered in the context of adiabatically changing environments. Subsequently, Aharonov and Anandan liberated this phase from the original formulation of Berry, which used Hamiltonians, dependent on curves in a classical parameter space, to represent the cyclic variations of the environments. Their purely quantum mechanical treatment, independent of Hamiltonians, instead used the non-trivial topological structure of the projective space of one-dimensional subspaces of an appropriate Hilbert space. The geometrical phase, in their treatment, results from a parallel transport of the time-dependent pure quantum states along a curve in this space, which is endowed with an abelian connection. Unlike Berry, they were able to achieve this without resort to an adiabatic approximation or to a time-independent eigenvalue equation. Prima facie, these two approaches are conceptually quite different. After a review of both approaches, an exposition bridging this apparent conceptual gap is given; by rigorously analyzing a model composite system, it is shown that, in an appropriate correspondence limit, the Berry phase can be recovered as a special case from the Aharonov-Anandan phase. Moreover, the model composite system is used to show that Berry's correction to the traditional Born-Oppenheimer energy spectra indeed brings the spectra closer to the exact results. Then, an experimental arrangement to measure geometrical phases associated with cyclic and non-cyclic variations of quantum states of an entangled composite system is proposed, utilizing the fundamental ideas of the recently opened field of two-particle interferometry. This arrangement not only resolves the controversy regarding the true nature of the phases associated with photon states, but also unequivocally predicts experimentally accessible geometrical phases in a
Directory of Open Access Journals (Sweden)
V.C.Uvaraja
2014-05-01
Full Text Available In the present study, an Al 7075 alloy is used as the matrix and varying weight percentage of Silicon Carbide (SiC and constant weight percentage of Boron Carbide (B4C as the reinforcing material. The composite is produced using stir casting technique. The composite thus formed is termed as hybrid composite. The samples are prepared for heat treatment process by subjecting to solutionizing temperature of 530o C for 1 hr followed by quenching in water. Further the specimens are subjected to artificial aging for durations of 4, 6 and 8 hr at a temperature of 175°C. The mechanical and tribological properties of composites before and after heat treatment are examined by Vickers hardness test machine and pin-on-disc test machine respectively. The wear rate and friction co-efficient of heat treatment parameters are evaluated based on Taguchi technique. The analysis is further extended to the optimization of test parameters using Design of Experiment (DoE based on L9 orthogonal array. The developed Analysis of Variance (ANOVA and the regression equations is obtained through MINITAB R16 are used to investigate the influence of parameters like sliding speed, applied load, sliding time, and percentage of reinforcement on the dry sliding wear and friction co-efficient of the composites. The wear surface morphology and wear mechanism of the pins are investigated using Scanning Electron Microscope (SEM and are correlated them with wear test results. Finally, confirmation tests are carried out to verify the experimental results.
Conceptual aspects of geometric quantum computation
Sjöqvist, Erik; Azimi Mousolou, Vahid; Canali, Carlo M.
2016-10-01
Geometric quantum computation is the idea that geometric phases can be used to implement quantum gates, i.e., the basic elements of the Boolean network that forms a quantum computer. Although originally thought to be limited to adiabatic evolution, controlled by slowly changing parameters, this form of quantum computation can as well be realized at high speed by using nonadiabatic schemes. Recent advances in quantum gate technology have allowed for experimental demonstrations of different types of geometric gates in adiabatic and nonadiabatic evolution. Here, we address some conceptual issues that arise in the realizations of geometric gates. We examine the appearance of dynamical phases in quantum evolution and point out that not all dynamical phases need to be compensated for in geometric quantum computation. We delineate the relation between Abelian and non-Abelian geometric gates and find an explicit physical example where the two types of gates coincide. We identify differences and similarities between adiabatic and nonadiabatic realizations of quantum computation based on non-Abelian geometric phases.
Geometric transition in Non-perturbative Topological string
Sugimoto, Yuji
2016-01-01
We study a geometric transition in non-perturbative topological string. We consider two cases. One is the geometric transition from the closed topological string on the local $\\mathcal{B}_{3}$ to the closed topological string on the resolved conifold. The other is the geometric transition from the closed topological string on the local $\\mathcal{B}_{3}$ to the open topological string on the resolved conifold with a toric A-brane. We find that, in both cases, the geometric transition can be applied for the non-perturbative topological string. We also find the corrections of the value of K\\"ahler parameters at which the geometric transition occurs.
Determination of CdIn{sub 2}S{sub 4} semiconductor parameters by (photo)electrochemical technique
Energy Technology Data Exchange (ETDEWEB)
Sawant, R.R. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India); Rajpure, K.Y. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India)]. E-mail: kyr_phy@unishivaji.ac.in; Bhosale, C.H. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India)
2007-04-30
Semiconducting n-CdIn{sub 2}S{sub 4} thin films have been deposited on amorphous and fluorine-doped tin oxide (FTO) coated glass substrates by using a well-known spray pyrolysis technique. With the objective of finding the optimum conditions for the deposition of CdIn{sub 2}S{sub 4} thin films, the influence of substrate temperature on properties of the films have been studied. Photoelectrochemical (PEC) technique has been employed to optimize substrate temperature. The films are characterized by the techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis by X-rays (EDAX) and PEC studies. The SEM studies reveal the compact morphology with large number of grains. EDAX studies show that the material formed at optimized substrate temperature is nearly stoichiometric. Measured values of efficiency ({eta}) and fill factor (FF) for the PEC cell are 1.06% and 0.47, respectively. Various physical parameters of cadmium indium sulphide (CdIn{sub 2}S{sub 4}) film are estimated. Energy band diagrams for CdIn{sub 2}S{sub 4} and polysulphide electrolyte, before and after making junction have been constructed.
Directory of Open Access Journals (Sweden)
G. González Rey
1999-01-01
Full Text Available La gran diversidad de los tipos y tamaños de transmisiones por engranajes que son empleados en Cuba, han dificultado lareparación generalizada de estos componentes y ha requerido que la recuperación de las ruedas dentadas necesite de métodosde ingeniería inversa que permita conocer los parámetros geométricos y constructivos básicos, para su posterior reconstruccióny/o evaluación de la capacidad de carga. Es de interés para la producción que los ingenieros mecánicos, vinculados al trabajocon transmisiones mecánicas, sean capaces de determinar, con un nivel de precisión medio, los parámetros geométricosfundamentales de los engranajes construidos y de los cuales se desconoce su geometría básica, a partir de mediciones de taller ycálculos ingenieriles. Por tal motivo, en el trabajo es referido un método practico para obtener los parámetros geométricosfundamentales del dentado de las ruedas de un engranaje cónico de dientes rectos convencional.Palabras claves: Engranajes cónicos de dientes rectos, recuperación, geometría, espesor dediente._____________________________________________________________________AbstractThe great diversity of gear types used in the Cuban industries have impeded the generalized repair of these components and hasrequired that the recovery of gearwheels need of inverse engineering methods to know the basic geometric parameters forposterior reconstruction and/or evaluation of the load capacity. Mechanical engineers linked with gear transmissions should becapable of determining, with a precision level middle, the fundamental geometric parameters of gears. For that reason, in thispaper is referred a practical method to obtain the fundamental geometric parameters of a straight bevel gear.Key words: Straight bevel gear, recovery, geometry, tooth thickness.
A history of geometrical methods
Coolidge, Julian Lowell
2013-01-01
Full and authoritative, this history of the techniques for dealing with geometric questions begins with synthetic geometry and its origins in Babylonian and Egyptian mathematics; reviews the contributions of China, Japan, India, and Greece; and discusses the non-Euclidean geometries. Subsequent sections cover algebraic geometry, starting with the precursors and advancing to the great awakening with Descartes; and differential geometry, from the early work of Huygens and Newton to projective and absolute differential geometry. The author's emphasis on proofs and notations, his comparisons betwe
Bueno, M.; Schulte, R.; Meylan, S.; Villagrasa, C.
2015-11-01
The aim of this study was to evaluate the influence of the geometrical detail of the DNA on nanodosimetric parameters of track structure induced by protons and alpha particles of different energies (LET values ranging from 1 to 162.5~\\text{keV}~μ {{\\text{m}}-1} ) as calculated by Geant4-DNA Monte Carlo simulations. The first geometry considered consisted of a well-structured placement of a realistic description of the DNA double helix wrapped around cylindrical histones (GeomHist) forming a 18 kbp-long chromatin fiber. In the second geometry considered, the DNA was modeled as a total of 1800 ten bp-long homogeneous cylinders (2.3 nm diameter and 3.4 nm height) placed in random positions and orientations (GeomCyl). As for GeomHist, GeomCyl contained a DNA material equivalent to 18 kbp. Geant4-DNA track structure simulations were performed and ionizations were counted in the scoring volumes. For GeomCyl, clusters were defined as the number of ionizations (ν) scored in each 10 bp-long cylinder. For GeomHist, clusters of ionizations scored in the sugar-phosphate groups of the double-helix were revealed by the DBSCAN clustering algorithm according to a proximity criteria among ionizations separated by less than 10 bp. The topology of the ionization clusters formed using GeomHist and GeomCyl geometries were compared in terms of biologically relevant nanodosimetric quantities. The discontinuous modeling of the DNA for GeomCyl led to smaller cluster sizes than for GeomHist. The continuous modeling of the DNA molecule for GeomHist allowed the merging of ionization points by the DBSCAN algorithm giving rise to larger clusters, which were not detectable within the GeomCyl geometry. Mean cluster size (m1) was found to be of the order of 10% higher for GeomHist compared to GeomCyl for LET <15~\\text{keV}~μ {{\\text{m}}-1} . For higher LETs, the difference increased with LET similarly for protons and alpha particles. Both geometries showed the same relationship
Anderson, Katherine H.; Bartlein, Patrick J.; Strickland, Laura E.; Pelltier, Richard T.; Thompson, Robert S.; Shafer, Sarah L.
2012-01-01
The mutual climatic range (MCR) technique is perhaps the most widely used method for estimating past climatic parameters from fossil assemblages, largely because it can be conducted on a simple list of the taxa present in an assemblage. When applied to plant macrofossil data, this unweighted approach (MCRun) will frequently identify a large range for a given climatic parameter where the species in an assemblage can theoretically live together. To narrow this range, we devised a new weighted approach (MCRwt) that employs information from the modern relations between climatic parameters and plant distributions to lessen the influence of the "tails" of the distributions of the climatic data associated with the taxa in an assemblage. To assess the performance of the MCR approaches, we applied them to a set of modern climatic data and plant distributions on a 25-km grid for North America, and compared observed and estimated climatic values for each grid point. In general, MCRwt was superior to MCRun in providing smaller anomalies, less bias, and better correlations between observed and estimated values. However, by the same measures, the results of Modern Analog Technique (MAT) approaches were superior to MCRwt. Although this might be reason to favor MAT approaches, they are based on assumptions that may not be valid for paleoclimatic reconstructions, including that: 1) the absence of a taxon from a fossil sample is meaningful, 2) plant associations were largely unaffected by past changes in either levels of atmospheric carbon dioxide or in the seasonal distributions of solar radiation, and 3) plant associations of the past are adequately represented on the modern landscape. To illustrate the application of these MCR and MAT approaches to paleoclimatic reconstructions, we applied them to a Pleistocene paleobotanical assemblage from the western United States. From our examinations of the estimates of modern and past climates from vegetation assemblages, we conclude that
GEOMETRICAL MODELING OF STRUCTURES USING CAD TECHNIQUES
1997-01-01
O Homem constrói estradas desde a Antigüidade. A técnica de projeto utilizada nos dias de hoje é resultado de um longo caminho de aperfeiçoamento que culminou em uma metodologia que procura atingir os melhores índices técnicos ao menor custo de execução possível. Pode-se dizer que esta tecnologia está bem definida desde o início da década de 40. Por sua vez, esta metodologia para ser otimizada requer uma quantidade enorme de cálculos que só podem ser feitos em ...
Geometric systematic prostate biopsy.
Chang, Doyoung; Chong, Xue; Kim, Chunwoo; Jun, Changhan; Petrisor, Doru; Han, Misop; Stoianovici, Dan
2017-04-01
The common sextant prostate biopsy schema lacks a three-dimensional (3D) geometric definition. The study objective was to determine the influence of the geometric distribution of the cores on the detection probability of prostate cancer (PCa). The detection probability of significant (>0.5 cm(3)) and insignificant (geometric distribution of the cores was optimized to maximize the probability of detecting significant cancer for various prostate sizes (20-100cm(3)), number of biopsy cores (6-40 cores) and biopsy core lengths (14-40 mm) for transrectal and transperineal biopsies. The detection of significant cancer can be improved by geometric optimization. With the current sextant biopsy, up to 20% of tumors may be missed at biopsy in a 20 cm(3) prostate due to the schema. Higher number and longer biopsy cores are required to sample with an equal detection probability in larger prostates. Higher number of cores increases both significant and insignificant tumor detection probability, but predominantly increases the detection of insignificant tumors. The study demonstrates mathematically that the geometric biopsy schema plays an important clinical role, and that increasing the number of biopsy cores is not necessarily helpful.
Liu, Jingjing; Shaltout, Amr M.; Ni, Xingjie; Shalaev, Vladimir M.; Kildishev, Alexander V.
2013-09-01
We report on a numerical study of a new bianisotropic parameter retrieval technique for both regular and complementary V-shape antenna metasurfaces. Each antenna element with a discrete phase shift is modeled by a homogenous bianisotropic film to represent the optical response. For the complementary design, the retrieval implies a complementary behavior of effective material properties and predicts the analogous functionalities. Further, FDFD solver is developed to integrate the bianisotropic descriptions of each antenna and describes a fully functional metasurface. The computational burden is significantly reduced, because effective material properties replace the detailed meshing of the antennas. Experimentally, large dimension arrays of nano-voids are fabricated using electron beam lithography. It is demonstrated that cross-polarized light is diffracted towards the same direction. Furthermore, the complementary design greatly increases the extinction ratio of functional fields to background fields.
Energy Technology Data Exchange (ETDEWEB)
Tuğluoğlu, Nihat, E-mail: tugluo@gmail.com [Department of Technology, Sarayköy Nuclear Research and Training Center, 06983 Saray, Ankara (Turkey); Barış, Behzad; Gürel, Hatice [Department of Physics, Faculty of Arts and Sciences, Giresun University, Gazipaşa Campus, Giresun 28100 (Turkey); Karadeniz, Serdar [Department of Technology, Sarayköy Nuclear Research and Training Center, 06983 Saray, Ankara (Turkey); Yüksel, Ömer Faruk [Department of Physics, Faculty of Science, Selçuk University, Campus Konya 42075 (Turkey)
2014-01-05
Highlights: • Thin film of rubrene has been deposited by spin coating technique. • The band gap properties of the film were investigated in the range 200–700 nm. • The analysis of the absorption coefficient revealed indirect allowed transition. • The parameters such as barrier height and ideality factor were determined. -- Abstract: Rubrene thin film has been deposited by spin coating technique. The optical band gap properties of rubrene thin film have been investigated in the spectral range 200–700 nm. The results of the absorption coefficient (α) were analyzed in order to determine the optical band gap and Urbach energy of the film. The absorption spectra recorded in the UV–vis region shows two peaks at 250 nm and 300 nm. The analysis of the spectral behavior of the absorption coefficient (α) in the absorption region revealed indirect allowed transition with corresponding energy 2.31 eV. The value of Urbach energy (E{sub U}) was determined to be 1.169 eV. The current–voltage (I–V) characteristics and electrical conduction properties of rubrene/n-Si device fabricated by spin coating method have also been investigated. The I–V characteristic in dark was showed the rectification effect due to the formation of Schottky barrier at rubrene/silicon interface. From analyzing the I-V measurement for the device, the basic device parameters such as barrier height, ideality factor and series resistance were determined. At the low-voltage region, the current conduction in Au/rubrene/n-Si device is ohmic type. The charge transport phenomenon appears to be space charge limited current (SCLC) at higher-voltage regions.
Nooruddin, Hasan A.; Anifowose, Fatai; Abdulraheem, Abdulazeez
2014-03-01
Soft computing techniques are recently becoming very popular in the oil industry. A number of computational intelligence-based predictive methods have been widely applied in the industry with high prediction capabilities. Some of the popular methods include feed-forward neural networks, radial basis function network, generalized regression neural network, functional networks, support vector regression and adaptive network fuzzy inference system. A comparative study among most popular soft computing techniques is presented using a large dataset published in literature describing multimodal pore systems in the Arab D formation. The inputs to the models are air porosity, grain density, and Thomeer parameters obtained using mercury injection capillary pressure profiles. Corrected air permeability is the target variable. Applying developed permeability models in recent reservoir characterization workflow ensures consistency between micro and macro scale information represented mainly by Thomeer parameters and absolute permeability. The dataset was divided into two parts with 80% of data used for training and 20% for testing. The target permeability variable was transformed to the logarithmic scale as a pre-processing step and to show better correlations with the input variables. Statistical and graphical analysis of the results including permeability cross-plots and detailed error measures were created. In general, the comparative study showed very close results among the developed models. The feed-forward neural network permeability model showed the lowest average relative error, average absolute relative error, standard deviations of error and root means squares making it the best model for such problems. Adaptive network fuzzy inference system also showed very good results.
Li, Biting; Seliman, Ayman; Pales, Ashley; Liang, Weizhen; Sams, Allison; Darnault, Christophe; Devol, Timothy
2017-04-01
The primary objectives of this research are to do the pH and O2 sensor foils calibration and then to test them in applications. Potentially, this project can be utilized to monitor the fate and transport of radionuclides in porous media. The information for physical and chemical parameters (e.g. pH and O2) is crucial to know when determining contaminants' behavior and transport in the environment. As a non-invasive method, optical imaging technique using a DSLR camera could capture data on the foil when it fluoresces, and gives a high temporal and spatial resolution during the experimental period. The calibration procedures were done in cuvettes in a row. The preliminary experiments could measure pH value in the range from 4.5 to 7.5, and O2 concentration from 0 mg/L to 20.74 mg/L. Applications of sensor foils have involved nano zero valent and acid rain experiments in order to obtain a gradient of parameter changes.
Geometric documentation of underwater archaeological sites
Directory of Open Access Journals (Sweden)
Eleni Diamanti
2013-12-01
Full Text Available Photogrammetry has often been the most preferable method for the geometric documentation of monuments, especially in cases of highly complex objects, of high accuracy and quality requirements and, of course, budget, time or accessibility limitations. Such limitations, requirements and complexities are undoubtedly features of the highly challenging task of surveying an underwater archaeological site. This paper is focused on the case of a Hellenistic shipwreck found in Greece at the Southern Euboean gulf, 40-47 meters below the sea surface. Underwater photogrammetry was chosen as the ideal solution for the detailed and accurate mapping of a shipwreck located in an environment with limited accessibility. There are time limitations when diving at these depths so it is essential that the data collection time is kept as short as possible. This makes custom surveying techniques rather impossible to apply. However, with the growing use of consumer cameras and photogrammetric software, this application is becoming easier, thus benefiting a wide variety of underwater sites. Utilizing cameras for underwater photogrammetry though, poses some crucial modeling problems, due to the refraction effect and further additional parameters which have to be co-estimated [1]. The applied method involved an underwater calibration of the camera as well as conventional field survey measurements in order to establish a reference frame. The application of a three-dimensional trilateration using common tape measures was chosen for this reason. Among the software that was used for surveying and photogrammetry processing, were Site Recorder SE, Eos Systems Photomodeler, ZI’s SSK and Rhinoceros. The underwater archaeological research at the Southern Euboean gulf is a continuing project carried out by the Hellenic Institute for Marine Archaeology (H.I.M.A. in collaboration with the Greek Ephorate of Underwater Antiquities, under the direction of the archaeologist G
Xu, Junqi; Kousaka, Hiroyuki; Umehara, Noritsugu; Diao, Dongfeng
2006-01-01
Hydrogen-free diamond-like carbon (DLC) films were deposited by a new-type surface wave-sustained plasma physical vapor deposition (SWP-PVD) system under various technique conditions. Electron density was measured by a Langmuir probe, while the film thickness and hardness were characterized using a surface profilometer and a nanoindenter, respectively. Surface morphology was investigated by an atomic force microscope (AFM). It was found that the electron density and deposition rate increased following the increase in microwave power, target voltage, or gas pressure. The typical electron density and deposition rate were about 1.87-2.04×10 11 cm -3 and 1.61-14.32 nm/min respectively. AFM images indicated that the grains of films changes as the technique parameters vary. The optical constants, refractive index n and extinction coefficient k, were obtained using an optical ellipsometry. With the increase in microwave power from 150 to 270 W, the extinction coefficient of DLC films increased from 0.05 to 0.27 while the refractive index decreased from 2.31 to 2.18.
MM Algorithms for Geometric and Signomial Programming.
Lange, Kenneth; Zhou, Hua
2014-02-01
This paper derives new algorithms for signomial programming, a generalization of geometric programming. The algorithms are based on a generic principle for optimization called the MM algorithm. In this setting, one can apply the geometric-arithmetic mean inequality and a supporting hyperplane inequality to create a surrogate function with parameters separated. Thus, unconstrained signomial programming reduces to a sequence of one-dimensional minimization problems. Simple examples demonstrate that the MM algorithm derived can converge to a boundary point or to one point of a continuum of minimum points. Conditions under which the minimum point is unique or occurs in the interior of parameter space are proved for geometric programming. Convergence to an interior point occurs at a linear rate. Finally, the MM framework easily accommodates equality and inequality constraints of signomial type. For the most important special case, constrained quadratic programming, the MM algorithm involves very simple updates.
PREFACE: Geometrically frustrated magnetism Geometrically frustrated magnetism
Gardner, Jason S.
2011-04-01
Frustrated magnetism is an exciting and diverse field in condensed matter physics that has grown tremendously over the past 20 years. This special issue aims to capture some of that excitement in the field of geometrically frustrated magnets and is inspired by the 2010 Highly Frustrated Magnetism (HFM 2010) meeting in Baltimore, MD, USA. Geometric frustration is a broad phenomenon that results from an intrinsic incompatibility between some fundamental interactions and the underlying lattice geometry based on triangles and tetrahedra. Most studies have centred around the kagomé and pyrochlore based magnets but recent work has looked at other structures including the delafossite, langasites, hyper-kagomé, garnets and Laves phase materials to name a few. Personally, I hope this issue serves as a great reference to scientist both new and old to this field, and that we all continue to have fun in this very frustrated playground. Finally, I want to thank the HFM 2010 organizers and all the sponsors whose contributions were an essential part of the success of the meeting in Baltimore. Geometrically frustrated magnetism contents Spangolite: an s = 1/2 maple leaf lattice antiferromagnet? T Fennell, J O Piatek, R A Stephenson, G J Nilsen and H M Rønnow Two-dimensional magnetism and spin-size effect in the S = 1 triangular antiferromagnet NiGa2S4 Yusuke Nambu and Satoru Nakatsuji Short range ordering in the modified honeycomb lattice compound SrHo2O4 S Ghosh, H D Zhou, L Balicas, S Hill, J S Gardner, Y Qi and C R Wiebe Heavy fermion compounds on the geometrically frustrated Shastry-Sutherland lattice M S Kim and M C Aronson A neutron polarization analysis study of moment correlations in (Dy0.4Y0.6)T2 (T = Mn, Al) J R Stewart, J M Hillier, P Manuel and R Cywinski Elemental analysis and magnetism of hydronium jarosites—model kagome antiferromagnets and topological spin glasses A S Wills and W G Bisson The Herbertsmithite Hamiltonian: μSR measurements on single crystals
Mahavira's Geometrical Problems
DEFF Research Database (Denmark)
Høyrup, Jens
2004-01-01
Analysis of the geometrical chapters Mahavira's 9th-century Ganita-sara-sangraha reveals inspiration from several chronological levels of Near-Eastern and Mediterranean mathematics: (1)that known from Old Babylonian tablets, c. 1800-1600 BCE; (2)a Late Babylonian but pre-Seleucid Stratum, probably...
Burgess, Claudia R.
2014-01-01
Designed for a broad audience, including educators, camp directors, afterschool coordinators, and preservice teachers, this investigation aims to help individuals experience mathematics in unconventional and exciting ways by engaging them in the physical activity of building geometric shapes using ropes. Through this engagement, the author…
Institute of Scientific and Technical Information of China (English)
谭杰; 金捷
2013-01-01
3-D Navier-Stokes calculations were carried out to investigate the effects of geometric parameters on internal performance and flowfield of single expansion ramp nozzles ( SERNs) . The results show that,in general,the nozzle sidewall extension has a beneficial effect on nozzle thrust. However,excessive large wetted surface area of sidewall results in great friction loss,which is already prevailing over the pressure gain by sidewall extension. The partial sidewalls perform slightly better than full sidewalls,and the axial thrust ratio Cfa is 2% larger than short sidewalls. Moreover,the extended sidewall reduces the pitch thrust vector angle δp effectively at the design point. The long curved ramp obtains higher Cfa and smaller δp than the short curved ramp,and the Cfa reaches 0. 983 at design point,which is comparable with the conventional axisymmetric and two-dimensional convergent-divergent (2DCD) nozzles. Under the conditions of relatively high nozzle pressure ratios (NPRs),large throat aspect ratio reduces the spanwise expansion losses effectively,with higher Cfa and smaller 5p,and the margin increases with increasing NPR.%采用三维数值模拟方法研究了单边膨胀喷管(SERN)主要几何参数对其内特性和流场的影响,计算结果表明:侧壁的延伸对SERN的轴向推力系数Cfa是有益的,但过大的侧壁浸湿面积会产生大的摩擦损失从而使推力性能下降；其中部分封闭侧壁的性能要略微高于全封闭式侧壁,而相比于短侧壁,其Cfa的优势在2％左右；此外,侧壁的延伸可以有效降低设计点的推力矢量角δp；长的曲壁模型拥有高Cfa的同时其δp处于较低的水平,在设计点条件下,最高Cfa可达0.983,这与传统的轴对称喷管和二元收扩喷管相差不大；在高落压比条件下,大的喷管喉道宽高比可以有效降低气流展向膨胀损失从而具有高的Cfa和低的δp,而且其优势随NPR的增大而增加.
Seong, Tae-Je
The similarity of item and ability parameter estimations was investigated using two numerical analysis techniques via marginal maximum likelihood estimation (MMLE) with a large simulated data set (n=1,000 examinees) and changing the number of quadrature points. MMLE estimation uses a numerical analysis technique to integrate examinees' abilities…
Geometric and Texture Inpainting by Gibbs Sampling
DEFF Research Database (Denmark)
Gustafsson, David Karl John; Pedersen, Kim Steenstrup; Nielsen, Mads
2007-01-01
This paper discuss a method suitable for inpainting both large scale geometric structures and more stochastic texture components. Image inpainting concerns the problem of reconstructing the intensity contents inside regions of missing data. Common techniques for solving this problem are methods...
Shi, Liguang; Ren, Youshe; Zhou, Hanlin; Hou, Guanyu; Xun, Wenjuan; Yue, Wenbin; Zhang, Chunxiang; Yang, Rujie
2014-02-01
Supercooling sperm in liquid nitrogen vapour is a feasible and economic technique for the practical production. The study aimed to reveal the negative effects of this rapid freezing and thawing processes on Taihang black goat spermatozoa and to find out the changing of spermatozoa motility and ultrastructure by using CASA and TEM. Qualified semen samples, which collected from twenty Chinese Taihang black goats using artificial vagina were pooled and investigated the kinematics parameters and ultrastructural morphology. The results showed that freezing-thawing caused a significant reduction in the spermatozoon total motility (Psperm nucleus characterized by ruptures, bend and deformity was observed. The plasma membranes were broken, and nucleoplasm erupted. The mitochondria in the middle piece were disturbed by partial absence or additional accumulations. Swelling, coiling, vacuolization and structural disorganization of mitochondria were also observed. In conclusion, Freezing-thawing procedure has a detrimental effect on motility, membrane integrity and mitochondria of goat spermatozoa. Transmission electron microscopy provides an intuitive observation to investigate deformity spermatozoa.
Frè, Pietro Giuseppe
2013-01-01
‘Gravity, a Geometrical Course’ presents general relativity (GR) in a systematic and exhaustive way, covering three aspects that are homogenized into a single texture: i) the mathematical, geometrical foundations, exposed in a self consistent contemporary formalism, ii) the main physical, astrophysical and cosmological applications, updated to the issues of contemporary research and observations, with glimpses on supergravity and superstring theory, iii) the historical development of scientific ideas underlying both the birth of general relativity and its subsequent evolution. The book is divided in two volumes. Volume One is dedicated to the development of the theory and basic physical applications. It guides the reader from the foundation of special relativity to Einstein field equations, illustrating some basic applications in astrophysics. A detailed account of the historical and conceptual development of the theory is combined with the presentation of its mathematical foundations. Differe...
Bestvina, Mladen; Vogtmann, Karen
2014-01-01
Geometric group theory refers to the study of discrete groups using tools from topology, geometry, dynamics and analysis. The field is evolving very rapidly and the present volume provides an introduction to and overview of various topics which have played critical roles in this evolution. The book contains lecture notes from courses given at the Park City Math Institute on Geometric Group Theory. The institute consists of a set of intensive short courses offered by leaders in the field, designed to introduce students to exciting, current research in mathematics. These lectures do not duplicate standard courses available elsewhere. The courses begin at an introductory level suitable for graduate students and lead up to currently active topics of research. The articles in this volume include introductions to CAT(0) cube complexes and groups, to modern small cancellation theory, to isometry groups of general CAT(0) spaces, and a discussion of nilpotent genus in the context of mapping class groups and CAT(0) gro...
Dynamics in geometrical confinement
Kremer, Friedrich
2014-01-01
This book describes the dynamics of low molecular weight and polymeric molecules when they are constrained under conditions of geometrical confinement. It covers geometrical confinement in different dimensionalities: (i) in nanometer thin layers or self supporting films (1-dimensional confinement) (ii) in pores or tubes with nanometric diameters (2-dimensional confinement) (iii) as micelles embedded in matrices (3-dimensional) or as nanodroplets.The dynamics under such conditions have been a much discussed and central topic in the focus of intense worldwide research activities within the last two decades. The present book discusses how the resulting molecular mobility is influenced by the subtle counterbalance between surface effects (typically slowing down molecular dynamics through attractive guest/host interactions) and confinement effects (typically increasing the mobility). It also explains how these influences can be modified and tuned, e.g. through appropriate surface coatings, film thicknesses or pore...
Geometric decompositions of collective motion
Mischiati, Matteo; Krishnaprasad, P. S.
2017-04-01
Collective motion in nature is a captivating phenomenon. Revealing the underlying mechanisms, which are of biological and theoretical interest, will require empirical data, modelling and analysis techniques. Here, we contribute a geometric viewpoint, yielding a novel method of analysing movement. Snapshots of collective motion are portrayed as tangent vectors on configuration space, with length determined by the total kinetic energy. Using the geometry of fibre bundles and connections, this portrait is split into orthogonal components each tangential to a lower dimensional manifold derived from configuration space. The resulting decomposition, when interleaved with classical shape space construction, is categorized into a family of kinematic modes-including rigid translations, rigid rotations, inertia tensor transformations, expansions and compressions. Snapshots of empirical data from natural collectives can be allocated to these modes and weighted by fractions of total kinetic energy. Such quantitative measures can provide insight into the variation of the driving goals of a collective, as illustrated by applying these methods to a publicly available dataset of pigeon flocking. The geometric framework may also be profitably employed in the control of artificial systems of interacting agents such as robots.
Progressive geometric algorithms
Directory of Open Access Journals (Sweden)
Sander P.A. Alewijnse
2015-01-01
Full Text Available Progressive algorithms are algorithms that, on the way to computing a complete solution to the problem at hand, output intermediate solutions that approximate the complete solution increasingly well. We present a framework for analyzing such algorithms, and develop efficient progressive algorithms for two geometric problems: computing the convex hull of a planar point set, and finding popular places in a set of trajectories.
Geometric unsharpness calculations
Energy Technology Data Exchange (ETDEWEB)
Anderson, D.J. [International Training and Education Group (INTEG), Oakville, Ontario (Canada)
2008-07-15
The majority of radiographers' geometric unsharpness calculations are normally performed with a mathematical formula. However, a majority of codes and standards refer to the use of a nomograph for this calculation. Upon first review, the use of a nomograph appears more complicated but with a few minutes of study and practice it can be just as effective. A review of this article should provide enlightenment. (author)
Geometric Stochastic Resonance
Ghosh, Pulak Kumar; Savel'ev, Sergey E; Nori, Franco
2015-01-01
A Brownian particle moving across a porous membrane subject to an oscillating force exhibits stochastic resonance with properties which strongly depend on the geometry of the confining cavities on the two sides of the membrane. Such a manifestation of stochastic resonance requires neither energetic nor entropic barriers, and can thus be regarded as a purely geometric effect. The magnitude of this effect is sensitive to the geometry of both the cavities and the pores, thus leading to distinctive optimal synchronization conditions.
Geometrically Consistent Mesh Modification
Bonito, A.
2010-01-01
A new paradigm of adaptivity is to execute refinement, coarsening, and smoothing of meshes on manifolds with incomplete information about their geometry and yet preserve position and curvature accuracy. We refer to this collectively as geometrically consistent (GC) mesh modification. We discuss the concept of discrete GC, show the failure of naive approaches, and propose and analyze a simple algorithm that is GC and accuracy preserving. © 2010 Society for Industrial and Applied Mathematics.
Geometric properties of eigenfunctions
Energy Technology Data Exchange (ETDEWEB)
Jakobson, D; Nadirashvili, N [McGill University, Montreal, Quebec (Canada); Toth, John [University of Chicago, Chicago, Illinois (United States)
2001-12-31
We give an overview of some new and old results on geometric properties of eigenfunctions of Laplacians on Riemannian manifolds. We discuss properties of nodal sets and critical points, the number of nodal domains, and asymptotic properties of eigenfunctions in the high-energy limit (such as weak * limits, the rate of growth of L{sup p} norms, and relationships between positive and negative parts of eigenfunctions)
Geometric theory of information
2014-01-01
This book brings together geometric tools and their applications for Information analysis. It collects current and many uses of in the interdisciplinary fields of Information Geometry Manifolds in Advanced Signal, Image & Video Processing, Complex Data Modeling and Analysis, Information Ranking and Retrieval, Coding, Cognitive Systems, Optimal Control, Statistics on Manifolds, Machine Learning, Speech/sound recognition, and natural language treatment which are also substantially relevant for the industry.
Perspective: Geometrically frustrated assemblies
Grason, Gregory M.
2016-09-01
This perspective will overview an emerging paradigm for self-organized soft materials, geometrically frustrated assemblies, where interactions between self-assembling elements (e.g., particles, macromolecules, proteins) favor local packing motifs that are incompatible with uniform global order in the assembly. This classification applies to a broad range of material assemblies including self-twisting protein filament bundles, amyloid fibers, chiral smectics and membranes, particle-coated droplets, curved protein shells, and phase-separated lipid vesicles. In assemblies, geometric frustration leads to a host of anomalous structural and thermodynamic properties, including heterogeneous and internally stressed equilibrium structures, self-limiting assembly, and topological defects in the equilibrium assembly structures. The purpose of this perspective is to (1) highlight the unifying principles and consequences of geometric frustration in soft matter assemblies; (2) classify the known distinct modes of frustration and review corresponding experimental examples; and (3) describe outstanding questions not yet addressed about the unique properties and behaviors of this broad class of systems.
Lloyd, Seth
2012-01-01
This letter analyzes the limits that quantum mechanics imposes on the accuracy to which spacetime geometry can be measured. By applying the fundamental physical bounds to measurement accuracy to ensembles of clocks and signals moving in curved spacetime -- e.g., the global positioning system -- I derive a covariant version of the quantum geometric limit: the total number of ticks of clocks and clicks of detectors that can be contained in a four volume of spacetime of radius r and temporal extent t is less than or equal to rt/\\pi x_P t_P, where x_P, t_P are the Planck length and time. The quantum geometric limit bounds the number of events or `ops' that can take place in a four-volume of spacetime: each event is associated with a Planck-scale area. Conversely, I show that if each quantum event is associated with such an area, then Einstein's equations must hold. The quantum geometric limit is consistent with and complementary to the holographic bound which limits the number of bits that can exist within a spat...
Model-based vision using geometric hashing
Akerman, Alexander, III; Patton, Ronald
1991-04-01
The Geometric Hashing technique developed by the NYU Courant Institute has been applied to various automatic target recognition applications. In particular, I-MATH has extended the hashing algorithm to perform automatic target recognition ofsynthetic aperture radar (SAR) imagery. For this application, the hashing is performed upon the geometric locations of dominant scatterers. In addition to being a robust model-based matching algorithm -- invariant under translation, scale, and 3D rotations of the target -- hashing is of particular utility because it can still perform effective matching when the target is partially obscured. Moreover, hashing is very amenable to a SIMD parallel processing architecture, and thus potentially realtime implementable.
Elastic scattering in geometrical model
Plebaniak, Zbigniew; Wibig, Tadeusz
2016-10-01
The experimental data on proton-proton elastic and inelastic scattering emerging from the measurements at the Large Hadron Collider, calls for an efficient model to fit the data. We have examined the optical, geometrical picture and we have found the simplest, linear dependence of this model parameters on the logarithm of the interaction energy with the significant change of the respective slopes at one point corresponding to the energy of about 300 GeV. The logarithmic dependence observed at high energies allows one to extrapolate the proton-proton elastic, total (and inelastic) cross sections to ultra high energies seen in cosmic rays events which makes a solid justification of the extrapolation to very high energy domain of cosmic rays and could help us to interpret the data from an astrophysical and a high energy physics point of view.
A Toolbox for Geometric Grain Boundary Characterization
Glowinski, Krzysztof; Morawiec, Adam
Properties of polycrystalline materials are affected by grain boundary networks. The most basic aspect of boundary analysis is boundary geometry. This paper describes a package of computer programs for geometric boundary characterization based on macroscopic boundary parameters. The program allows for determination whether a boundary can be classified as near-tilt, -twist, -symmetric et cetera. Since calculations on experimental, i.e., error affected data are assumed, the program also provides distances to the nearest geometrically characteristic boundaries. The software has a number of other functions helpful in grain boundary analysis. One of them is the determination of planes of all characteristic boundaries for a given misorientation. The resulting diagrams of geometrically characteristic boundaries can be linked to experimentally determined grain boundary distributions. In computations, all symmetrically equivalent representations of boundaries are taken into account. Cubic and hexagonal holohedral crystal symmetries are allowed.
Erfanifard, Yousef; Stereńczak, Krzysztof; Behnia, Negin
2014-01-01
Estimating the optimal parameters of some classification techniques becomes their negative aspect as it affects their performance for a given dataset and reduces classification accuracy. It was aimed to optimize the combination of effective parameters of support vector machine (SVM), artificial neural network (ANN), and object-based image analysis (OBIA) classification techniques by the Taguchi method. The optimized techniques were applied to delineate crowns of Persian oak coppice trees on UltraCam-D very high spatial resolution aerial imagery in Zagros semiarid woodlands, Iran. The imagery was classified and the maps were assessed by receiver operating characteristic curve and other performance metrics. The results showed that Taguchi is a robust approach to optimize the combination of effective parameters in these image classification techniques. The area under curve (AUC) showed that the optimized OBIA could well discriminate tree crowns on the imagery (AUC=0.897), while SVM and ANN yielded slightly less AUC performances of 0.819 and 0.850, respectively. The indices of accuracy (0.999) and precision (0.999) and performance metrics of specificity (0.999) and sensitivity (0.999) in the optimized OBIA were higher than with other techniques. The optimization of effective parameters of image classification techniques by the Taguchi method, thus, provided encouraging results to discriminate the crowns of Persian oak coppice trees on UltraCam-D aerial imagery in Zagros semiarid woodlands.
Algebraic geometric codes with applications
Institute of Scientific and Technical Information of China (English)
CHEN Hao
2007-01-01
The theory of linear error-correcting codes from algebraic geomet-ric curves (algebraic geometric (AG) codes or geometric Goppa codes) has been well-developed since the work of Goppa and Tsfasman, Vladut, and Zink in 1981-1982. In this paper we introduce to readers some recent progress in algebraic geometric codes and their applications in quantum error-correcting codes, secure multi-party computation and the construction of good binary codes.
Energy Technology Data Exchange (ETDEWEB)
Akın, Ümmühan, E-mail: uakin@selcuk.edu.tr; Şafak, Haluk
2015-10-25
The optical behaviors of molybdenum oxide thin films are highly important due to their widespread applications. In the present paper, the effect of thickness on the structure, morphology and optical properties of molybdenum oxide (MoO{sub x}) thin films prepared on Corning glass substrates using thermal evaporation technique was studied. The structure and morphology of films were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively, while their optical properties were investigated by UV-VIS-NIR spectrophotometry in the spectral range from 300 to 2500 nm. It was observed that whole films have amorphous structure and also they showed rather high transmittance values reached nearly up to 90%. Absorption analysis showed two types of electronic transitions; both direct and indirect interband transition energy values of films decrease from 4.47 to 3.45 eV and from 3.00 to 2.75 eV, respectively, with increasing the film thickness, while the width of the localized states tail increases with thickness. This decrease in the band gap value can be attributed to the rising oxygen-ion vacancy densities with the thickness. The refractive indices of films were calculated from Sellmeier coefficients determined by nonlinear curve fitting method based on the measured transmittance spectral data. The dispersion of the refractive index was discussed in terms of the Wemple-DiDomenico single-oscillator model. The dispersion parameters such as average oscillator energy, E{sub o}, the dispersion energy, E{sub d}, and static refractive index n{sub o} were evaluated and they found to vary significantly with the film thickness. - Highlights: • MoO{sub x} thin films with different thickness were prepared using the vacuum evaporation technique. • The variation of fundamental absorption edge with the film thickness was determined. • A detailed dispersion analysis based on the Wemple-DiDomenico model was performed. • The dependence of all
LUNGEOMETRY- GEOMETRICAL INVESTIGATION OF LUNGE
Directory of Open Access Journals (Sweden)
R.Vinodh Rajkumar
2015-02-01
Full Text Available Physiotherapists must learn the biomechanics of lunge in detail to clearly understand its significance in human life and implement effective training measures to overcome the limiting factors of proper lunge of their clientele. To understand the biomechanical value of every movement, interesting experimental learning methods must be employed to kindle the Physiotherapists to actively take part in research activities from the under-graduate level onwards. Lungeometry is a novel, simple and inexpensive experimental investigation of lunge, applying basic geometrical methods taking near normal lower limb length dimensions and rationale approaches into consideration. Lungeometry can give a foundation to learn other forms of lunges like forward lunge, weighted lunges, lateral lunges. This model of learning biomechanics of movements using fundamental geometry techniques is expected to strongly connect with any futuristic Physiotherapy curricular structure.
Geometric model of robotic arc welding for automatic programming
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
Geometric information is important for automatic programming of arc welding robot. Complete geometric models of robotic arc welding are established in this paper. In the geometric model of weld seam, an equation with seam length as its parameter is introduced to represent any weld seam. The method to determine discrete programming points on a weld seam is presented. In the geometric model of weld workpiece, three class primitives and CSG tree are used to describe weld workpiece. Detailed data structure is presented. In pose transformation of torch, world frame, torch frame and active frame are defined, and transformation between frames is presented. Based on these geometric models, an automatic programming software package for robotic arc welding, RAWCAD, is developed. Experiments show that the geometric models are practical and reliable.
Fuzzy Decision-Making Approach in Geometric Programming for a Single Item EOQ Model
Directory of Open Access Journals (Sweden)
Monalisha Pattnaik
2015-06-01
Full Text Available Background and methods: Fuzzy decision-making approach is allowed in geometric programming for a single item EOQ model with dynamic ordering cost and demand-dependent unit cost. The setup cost varies with the quantity produced/purchased and the modification of objective function with storage area in the presence of imprecisely estimated parameters are investigated. It incorporates all concepts of a fuzzy arithmetic approach, the quantity ordered, and demand per unit compares both fuzzy geometric programming technique and other models for linear membership functions. Results and conclusions: Investigation of the properties of an optimal solution allows developing an algorithm whose validity is illustrated through an example problem and the results discu ssed. Sensitivity analysis of the optimal solution is also studied with respect to changes in different parameter values.
Monte Carlo based geometrical model for efficiency calculation of an n-type HPGe detector
Energy Technology Data Exchange (ETDEWEB)
Padilla Cabal, Fatima, E-mail: fpadilla@instec.c [Instituto Superior de Tecnologias y Ciencias Aplicadas, ' Quinta de los Molinos' Ave. Salvador Allende, esq. Luaces, Plaza de la Revolucion, Ciudad de la Habana, CP 10400 (Cuba); Lopez-Pino, Neivy; Luis Bernal-Castillo, Jose; Martinez-Palenzuela, Yisel; Aguilar-Mena, Jimmy; D' Alessandro, Katia; Arbelo, Yuniesky; Corrales, Yasser; Diaz, Oscar [Instituto Superior de Tecnologias y Ciencias Aplicadas, ' Quinta de los Molinos' Ave. Salvador Allende, esq. Luaces, Plaza de la Revolucion, Ciudad de la Habana, CP 10400 (Cuba)
2010-12-15
A procedure to optimize the geometrical model of an n-type detector is described. Sixteen lines from seven point sources ({sup 241}Am, {sup 133}Ba, {sup 22}Na, {sup 60}Co, {sup 57}Co, {sup 137}Cs and {sup 152}Eu) placed at three different source-to-detector distances (10, 20 and 30 cm) were used to calibrate a low-background gamma spectrometer between 26 and 1408 keV. Direct Monte Carlo techniques using the MCNPX 2.6 and GEANT 4 9.2 codes, and a semi-empirical procedure were performed to obtain theoretical efficiency curves. Since discrepancies were found between experimental and calculated data using the manufacturer parameters of the detector, a detail study of the crystal dimensions and the geometrical configuration is carried out. The relative deviation with experimental data decreases from a mean value of 18-4%, after the parameters were optimized.
Monte Carlo based geometrical model for efficiency calculation of an n-type HPGe detector.
Cabal, Fatima Padilla; Lopez-Pino, Neivy; Bernal-Castillo, Jose Luis; Martinez-Palenzuela, Yisel; Aguilar-Mena, Jimmy; D'Alessandro, Katia; Arbelo, Yuniesky; Corrales, Yasser; Diaz, Oscar
2010-12-01
A procedure to optimize the geometrical model of an n-type detector is described. Sixteen lines from seven point sources ((241)Am, (133)Ba, (22)Na, (60)Co, (57)Co, (137)Cs and (152)Eu) placed at three different source-to-detector distances (10, 20 and 30 cm) were used to calibrate a low-background gamma spectrometer between 26 and 1408 keV. Direct Monte Carlo techniques using the MCNPX 2.6 and GEANT 4 9.2 codes, and a semi-empirical procedure were performed to obtain theoretical efficiency curves. Since discrepancies were found between experimental and calculated data using the manufacturer parameters of the detector, a detail study of the crystal dimensions and the geometrical configuration is carried out. The relative deviation with experimental data decreases from a mean value of 18-4%, after the parameters were optimized.
Geometric optimization and sums of algebraic functions
Vigneron, Antoine E.
2014-01-01
We present a new optimization technique that yields the first FPTAS for several geometric problems. These problems reduce to optimizing a sum of nonnegative, constant description complexity algebraic functions. We first give an FPTAS for optimizing such a sum of algebraic functions, and then we apply it to several geometric optimization problems. We obtain the first FPTAS for two fundamental geometric shape-matching problems in fixed dimension: maximizing the volume of overlap of two polyhedra under rigid motions and minimizing their symmetric difference. We obtain the first FPTAS for other problems in fixed dimension, such as computing an optimal ray in a weighted subdivision, finding the largest axially symmetric subset of a polyhedron, and computing minimum-area hulls.
Geometric Effects on the Amplification of First Mode Instability Waves
Kirk, Lindsay C.; Candler, Graham V.
2013-01-01
The effects of geometric changes on the amplification of first mode instability waves in an external supersonic boundary layer were investigated using numerical techniques. Boundary layer stability was analyzed at Mach 6 conditions similar to freestream conditions obtained in quiet ground test facilities so that results obtained in this study may be applied to future test article design to measure first mode instability waves. The DAKOTA optimization software package was used to optimize an axisymmetric geometry to maximize the amplification of the waves at first mode frequencies as computed by the 2D STABL hypersonic boundary layer stability analysis tool. First, geometric parameters such as nose radius, cone half angle, vehicle length, and surface curvature were examined separately to determine the individual effects on the first mode amplification. Finally, all geometric parameters were allowed to vary to produce a shape optimized to maximize the amplification of first mode instability waves while minimizing the amplification of second mode instability waves. Since first mode waves are known to be most unstable in the form of oblique wave, the geometries were optimized using a broad range of wave frequencies as well as a wide range of oblique wave angles to determine the geometry that most amplifies the first mode waves. Since first mode waves are seen most often in flows with low Mach numbers at the edge of the boundary layer, the edge Mach number for each geometry was recorded to determine any relationship between edge Mach number and the stability of first mode waves. Results indicate that an axisymmetric cone with a sharp nose and a slight flare at the aft end under the Mach 6 freestream conditions used here will lower the Mach number at the edge of the boundary layer to less than 4, and the corresponding stability analysis showed maximum first mode N factors of 3.
Morphing of geometric composites via residual swelling.
Pezzulla, Matteo; Shillig, Steven A; Nardinocchi, Paola; Holmes, Douglas P
2015-08-07
Understanding and controlling the shape of thin, soft objects has been the focus of significant research efforts among physicists, biologists, and engineers in the last decade. These studies aim to utilize advanced materials in novel, adaptive ways such as fabricating smart actuators or mimicking living tissues. Here, we present the controlled growth-like morphing of 2D sheets into 3D shapes by preparing geometric composite structures that deform by residual swelling. The morphing of these geometric composites is dictated by both swelling and geometry, with diffusion controlling the swelling-induced actuation, and geometric confinement dictating the structure's deformed shape. Building on a simple mechanical analog, we present an analytical model that quantitatively describes how the Gaussian and mean curvatures of a thin disk are affected by the interplay among geometry, mechanics, and swelling. This model is in excellent agreement with our experiments and numerics. We show that the dynamics of residual swelling is dictated by a competition between two characteristic diffusive length scales governed by geometry. Our results provide the first 2D analog of Timoshenko's classical formula for the thermal bending of bimetallic beams - our generalization explains how the Gaussian curvature of a 2D geometric composite is affected by geometry and elasticity. The understanding conferred by these results suggests that the controlled shaping of geometric composites may provide a simple complement to traditional manufacturing techniques.
Geometric Number Systems and Spinors
Sobczyk, Garret
2015-01-01
The real number system is geometrically extended to include three new anticommuting square roots of plus one, each such root representing the direction of a unit vector along the orthonormal coordinate axes of Euclidean 3-space. The resulting geometric (Clifford) algebra provides a geometric basis for the famous Pauli matrices which, in turn, proves the consistency of the rules of geometric algebra. The flexibility of the concept of geometric numbers opens the door to new understanding of the nature of space-time, and of Pauli and Dirac spinors as points on the Riemann sphere, including Lorentz boosts.
Bose, Prosenjit; Morin, Pat; Smid, Michiel
2012-01-01
Highly connected and yet sparse graphs (such as expanders or graphs of high treewidth) are fundamental, widely applicable and extensively studied combinatorial objects. We initiate the study of such highly connected graphs that are, in addition, geometric spanners. We define a property of spanners called robustness. Informally, when one removes a few vertices from a robust spanner, this harms only a small number of other vertices. We show that robust spanners must have a superlinear number of edges, even in one dimension. On the positive side, we give constructions, for any dimension, of robust spanners with a near-linear number of edges.
Corrochano, Eduardo Bayro
2010-01-01
This book presents contributions from a global selection of experts in the field. This useful text offers new insights and solutions for the development of theorems, algorithms and advanced methods for real-time applications across a range of disciplines. Written in an accessible style, the discussion of all applications is enhanced by the inclusion of numerous examples, figures and experimental analysis. Features: provides a thorough discussion of several tasks for image processing, pattern recognition, computer vision, robotics and computer graphics using the geometric algebra framework; int
Shapere, Alfred D
1989-01-01
During the last few years, considerable interest has been focused on the phase that waves accumulate when the equations governing the waves vary slowly. The recent flurry of activity was set off by a paper by Michael Berry, where it was found that the adiabatic evolution of energy eigenfunctions in quantum mechanics contains a phase of geometric origin (now known as 'Berry's phase') in addition to the usual dynamical phase derived from Schrödinger's equation. This observation, though basically elementary, seems to be quite profound. Phases with similar mathematical origins have been identified
Gopalakrishnan, T.; Saravanan, R.
2017-03-01
Powerful management concepts step-up the quality of the product, time saving in producing the product thereby increase the production rate, improves tools and techniques, work culture, work place and employee motivation and morale. In this paper discussed about the case study of optimizing the tool design, tool parameters to cast off expansion plan according ECRS technique. The proposed designs and optimal tool parameters yielded best results and meet the customer demand without expansion plan. Hence the work yielded huge savings of money (direct and indirect cost), time and improved the motivation and more of employees significantly.
Geometric perturbation theory and plasma physics
Energy Technology Data Exchange (ETDEWEB)
Omohundro, S.M.
1985-04-04
Modern differential geometric techniques are used to unify the physical asymptotics underlying mechanics, wave theory and statistical mechanics. The approach gives new insights into the structure of physical theories and is suited to the needs of modern large-scale computer simulation and symbol manipulation systems. A coordinate-free formulation of non-singular perturbation theory is given, from which a new Hamiltonian perturbation structure is derived and related to the unperturbed structure. The theory of perturbations in the presence of symmetry is developed, and the method of averaging is related to reduction by a circle group action. The pseudo-forces and magnetic Poisson bracket terms due to reduction are given a natural asymptotic interpretation. Similar terms due to changing reference frames are related to the method of variation of parameters, which is also given a Hamiltonian formulation. These methods are used to answer a question about nearly periodic systems. The answer leads to a new secular perturbation theory that contains no ad hoc elements. Eikonal wave theory is given a Hamiltonian formulation that generalizes Whitham's Lagrangian approach. The evolution of wave action density on ray phase space is given a Hamiltonian structure using a Lie-Poisson bracket. The relationship between dissipative and Hamiltonian systems is discussed. A new type of attractor is defined which attracts both forward and backward in time and is shown to occur in infinite-dimensional Hamiltonian systems with dissipative behavior. The theory of Smale horseshoes is applied to gyromotion in the neighborhood of a magnetic field reversal and the phenomenon of reinsertion in area-preserving horseshoes is introduced. The central limit theorem is proved by renormalization group techniques. A natural symplectic structure for thermodynamics is shown to arise asymptotically from the maximum entropy formalism.
Weinberg, I.
1975-01-01
The feasibility of using the MOS C-V technique to obtain information regarding impurity and surface state concentrations on the diffused face of silicon solar cells with Ta2O5 coatings is studied. Results indicate that the MOS C-V technique yields useful information concerning surface parameters which contribute to the high, efficiency limiting, surface recombination velocities on the n+ surface of silicon solar cells.
Ma, Y. Q.; Qi, L. H.; Zhou, J. M.; Zhang, T.; Li, H. J.
2017-02-01
Two-dimensional, carbon-fiber-reinforced aluminum matrix composites (2D- C f/Al composites) were prepared using liquid-solid extrusion by following the vacuum infiltration technique (LSEVI), which was an integrated and comprehensive process that resulted in as composite special-shaped part with ideal infiltration and a satisfied forming effect. According to the current research, we found preheating temperature, squeeze temperature, squeeze pressure, and melting temperature were the key parameters of the LSEVI technique, and it was very important to optimize these process parameters to obtain the ideal composite part. Through the research of orthogonal experimental design of these process parameters, results showed that squeeze pressure was the most significant influence parameter, and optimized parameters of aforementioned parameters were 888 K, 893 K, and 1053 K (615 °C, 620 °C, and 780 °C), 70 MPa, respectively. An infiltration effect of the C f/Al composite was full and uniform, and preparation defects could be avoided effectively under the above process parameters. Two-dimensional (2D) T300 carbon fiber preform was prepared by the method of carbon fiber laminates, and the 2D- C f/Al composite special-shaped part was fabricated successfully using the former optimized parameters of LSEVI. Results indicated a forming effect of the special-shaped part was obtained and that its sizes were reasonable. Through the analyses of microstructure and tensile property test, its infiltration effect and fracture morphology were satisfied. Carbon fibers in the composite played the reinforced effect effectively, so the ultimate tensile strength of the composite part was improved by 115.8 pct than that of the matrix, which proved that the optimized process parameters of the LSEVI technique were reasonable.
Bidimensionality and Geometric Graphs
Fomin, Fedor V; Saurabh, Saket
2011-01-01
In this paper we use several of the key ideas from Bidimensionality to give a new generic approach to design EPTASs and subexponential time parameterized algorithms for problems on classes of graphs which are not minor closed, but instead exhibit a geometric structure. In particular we present EPTASs and subexponential time parameterized algorithms for Feedback Vertex Set, Vertex Cover, Connected Vertex Cover, Diamond Hitting Set, on map graphs and unit disk graphs, and for Cycle Packing and Minimum-Vertex Feedback Edge Set on unit disk graphs. Our results are based on the recent decomposition theorems proved by Fomin et al [SODA 2011], and our algorithms work directly on the input graph. Thus it is not necessary to compute the geometric representations of the input graph. To the best of our knowledge, these results are previously unknown, with the exception of the EPTAS and a subexponential time parameterized algorithm on unit disk graphs for Vertex Cover, which were obtained by Marx [ESA 2005] and Alber and...
Manwani, Naresh
2010-01-01
In this paper we present a new algorithm for learning oblique decision trees. Most of the current decision tree algorithms rely on impurity measures to assess the goodness of hyperplanes at each node while learning a decision tree in a top-down fashion. These impurity measures do not properly capture the geometric structures in the data. Motivated by this, our algorithm uses a strategy to assess the hyperplanes in such a way that the geometric structure in the data is taken into account. At each node of the decision tree, we find the clustering hyperplanes for both the classes and use their angle bisectors as the split rule at that node. We show through empirical studies that this idea leads to small decision trees and better performance. We also present some analysis to show that the angle bisectors of clustering hyperplanes that we use as the split rules at each node, are solutions of an interesting optimization problem and hence argue that this is a principled method of learning a decision tree.
A geometric construction of traveling waves in a bioremediation model
Beck, M.A.; Doelman, A.; Kaper, T.J.
2006-01-01
Bioremediation is a promising technique for cleaning contaminated soil. We study an idealized bioremediation model involving a substrate (contaminant to be removed), electron acceptor (added nutrient), and microorganisms in a one-dimensional soil column. Using geometric singular perturbation theory,
PNE Coda Attenuation and Scattering Parameters in Northern Eurasia
2008-09-01
Iterative Reconstruction Technique ( SIRT ) are used for unbiased inversion. The resulting map of the geometrical parameter (γ) is in excellent agreement...iterative nature of the SIRT (Simultaneous Iterative Reconstruction Technique) solver that we employed. After each iteration, the solution was corrected to...triangulation. However, we did not use such constraints in the solution presented below. To invert for γi, κi, λi, and ζn numerically, we used the SIRT
Land-surface parameter optimisation using data assimilation techniques: the adJULES system V1.0
Raoult, Nina M.; Jupp, Tim E.; Cox, Peter M.; Luke, Catherine M.
2016-08-01
Land-surface models (LSMs) are crucial components of the Earth system models (ESMs) that are used to make coupled climate-carbon cycle projections for the 21st century. The Joint UK Land Environment Simulator (JULES) is the land-surface model used in the climate and weather forecast models of the UK Met Office. JULES is also extensively used offline as a land-surface impacts tool, forced with climatologies into the future. In this study, JULES is automatically differentiated with respect to JULES parameters using commercial software from FastOpt, resulting in an analytical gradient, or adjoint, of the model. Using this adjoint, the adJULES parameter estimation system has been developed to search for locally optimum parameters by calibrating against observations. This paper describes adJULES in a data assimilation framework and demonstrates its ability to improve the model-data fit using eddy-covariance measurements of gross primary production (GPP) and latent heat (LE) fluxes. adJULES also has the ability to calibrate over multiple sites simultaneously. This feature is used to define new optimised parameter values for the five plant functional types (PFTs) in JULES. The optimised PFT-specific parameters improve the performance of JULES at over 85 % of the sites used in the study, at both the calibration and evaluation stages. The new improved parameters for JULES are presented along with the associated uncertainties for each parameter.
Johnson, I. L., Jr.
1976-01-01
The Fletcher-Powell version of the Davidon variable metric unconstrained minimization technique is described. Equations that have been used successfully with the Davidon-Fletcher-Powell penalty function technique for solving constrained minimization problems and the advantages and disadvantages of using them are discussed. The experience gained in the behavior of the method while iterating is also related.
Geometric Complexity Theory: Introduction
Sohoni, Ketan D Mulmuley Milind
2007-01-01
These are lectures notes for the introductory graduate courses on geometric complexity theory (GCT) in the computer science department, the university of Chicago. Part I consists of the lecture notes for the course given by the first author in the spring quarter, 2007. It gives introduction to the basic structure of GCT. Part II consists of the lecture notes for the course given by the second author in the spring quarter, 2003. It gives introduction to invariant theory with a view towards GCT. No background in algebraic geometry or representation theory is assumed. These lecture notes in conjunction with the article \\cite{GCTflip1}, which describes in detail the basic plan of GCT based on the principle called the flip, should provide a high level picture of GCT assuming familiarity with only basic notions of algebra, such as groups, rings, fields etc.
The Geometric Transition Revisited
Gwyn, Rhiannon
2007-01-01
Our intention in this article is to review known facts and to summarise recent advances in the understanding of geometric transitions and the underlying open/closed duality in string theory. We aim to present a pedagogical discussion of the gauge theory underlying the Klebanov--Strassler model and review the Gopakumar--Vafa conjecture based on topological string theory. These models are also compared in the T-dual brane constructions. We then summarise a series of papers verifying both models on the supergravity level. An appendix provides extensive background material about conifold geometries. We pay special attention to their complex structures and re-evaluate the supersymmetry conditions on the background flux in constructions with fractional D3-branes on the singular (Klebanov--Strassler) and resolved (Pando Zayas--Tseytlin) conifolds. We agree with earlier results that only the singular solution allows a supersymmetric flux, but point out the importance of using the correct complex structure to reach th...
Geometrical Destabilization of Inflation
Renaux-Petel, Sébastien; Turzyński, Krzysztof
2016-09-01
We show the existence of a general mechanism by which heavy scalar fields can be destabilized during inflation, relying on the fact that the curvature of the field space manifold can dominate the stabilizing force from the potential and destabilize inflationary trajectories. We describe a simple and rather universal setup in which higher-order operators suppressed by a large energy scale trigger this instability. This phenomenon can prematurely end inflation, thereby leading to important observational consequences and sometimes excluding models that would otherwise perfectly fit the data. More generally, it modifies the interpretation of cosmological constraints in terms of fundamental physics. We also explain how the geometrical destabilization can lead to powerful selection criteria on the field space curvature of inflationary models.
Kukreja, Sunil L.; Wallin, Ragnar; Boyle, Richard D.
2013-01-01
The vestibulo-ocular reflex (VOR) is a well-known dual mode bifurcating system that consists of slow and fast modes associated with nystagmus and saccade, respectively. Estimation of continuous-time parameters of nystagmus and saccade models are known to be sensitive to estimation methodology, noise and sampling rate. The stable and accurate estimation of these parameters are critical for accurate disease modelling, clinical diagnosis, robotic control strategies, mission planning for space exploration and pilot safety, etc. This paper presents a novel indirect system identification method for the estimation of continuous-time parameters of VOR employing standardised least-squares with dual sampling rates in a sparse structure. This approach permits the stable and simultaneous estimation of both nystagmus and saccade data. The efficacy of this approach is demonstrated via simulation of a continuous-time model of VOR with typical parameters found in clinical studies and in the presence of output additive noise.
Jiang, Zhi Hao; Bossard, Jeremy A.; Wang, Xiande; Werner, Douglas H.
2011-01-01
In this paper, we present a method to retrieve the effective electromagnetic parameters of a slab of anisotropic metamaterial from reflection and transmission coefficients (or scattering parameters). In this retrieval method, calculated or measured scattering parameters are employed for plane waves incident obliquely on a metamaterial slab at different angles. Useful analytical expressions are derived for extracting the homogeneous anisotropic medium parameters of a metamaterial. To validate the method, the effective permittivity and permeability tensor parameters for a composite split-ring resonator-wire array are retrieved and shown to be consistent with observations previously reported in the literature. This retrieval method is further incorporated into a genetic algorithm (GA) to synthesize an infrared zero-index-metamaterial with a wide field-of-view, demonstrating the utility of the new design approach. The anisotropic parameter retrieval algorithm, when combined with a robust optimizer such as GA, can provide a powerful design tool for exploiting the anisotropic properties in metamaterials to achieve specific angle dependant or independent responses.
Geometrical Methods for Power Network Analysis
Bellucci, Stefano; Gupta, Neeraj
2013-01-01
This book is a short introduction to power system planning and operation using advanced geometrical methods. The approach is based on well-known insights and techniques developed in theoretical physics in the context of Riemannian manifolds. The proof of principle and robustness of this approach is examined in the context of the IEEE 5 bus system. This work addresses applied mathematicians, theoretical physicists and power engineers interested in novel mathematical approaches to power network theory.
Pohlert, Thorsten; Hillebrand, Gudrun; Breitung, Vera
2011-06-01
This study focusses on the effect of sampling techniques for suspended matter in stream water on subsequent particle-size distribution and concentrations of total organic carbon and selected persistent organic pollutants. The key questions are whether differences between the sampling techniques are due to the separation principle of the devices or due to the difference between time-proportional versus integral sampling. Several multivariate homogeneity tests were conducted on an extensive set of field-data that covers the period from 2002 to 2007, when up to three different sampling techniques were deployed in parallel at four monitoring stations of the River Rhine. The results indicate homogeneity for polychlorinated biphenyls, but significant effects due to the sampling techniques on particle-size, organic carbon and hexachlorobenzene. The effects can be amplified depending on the site characteristics of the monitoring stations.
Rochitte, Carlos Eduardo; Azevedo, Clerio F; Rosário, Miguel A; Siqueira, Maria H R; Monsão, Victor; Saranathan, Manoj; Foo, Thomas K; Kalil Filho, Roberto; Cerri, Giovanni G; Ramires, José A F
2011-01-01
The accurate and reproducible assessment of cardiac volumes, function, and mass is of paramount importance in cardiology. In the present study we sought to determine whether the 3D cine-magnetic resonance (MR) technique, using the variable asymmetric sampling in time (VAST) approach, provided an accurate assessment of LV functional parameters when compared with the conventional 2D cine-MR technique. A total of 43 consecutive patients referred for a CMR examination for clinical reasons and 14 healthy volunteers were included in the study. Cine images were acquired using a steady-state free precession pulse sequence. Two different multiphase acquisitions were performed: conventional 2D cine-MR and 3D cine-MR. The short-axis cine images acquired by both cine-MR techniques were used for the quantitative assessment of LV end-diastolic, end-systolic and stroke volumes, LV mass and ejection fraction. All CMR examinations were completed successfully, with both cine-MR imaging techniques yielding interpretable diagnostic results in all patients. Regarding the quantitative assessment, Bland-Altman analyses demonstrated a good agreement between the measurements of both cine-MR techniques for all LV parameters. In addition, the agreement between 2D and 3D cine-MR techniques for the qualitative assessment of LV global function was perfect (kappa = 1.0, Ptechnique provides an accurate and reproducible quantitative assessment of LV volumes, mass and function when compared with the conventional 2D cine-MR method.
Geometric Mechanics of Periodic Pleated Origami
Wei, Zhiyan; Dudte, Levi; Liang, Haiyi; Mahadevan, L
2012-01-01
Origami is the archetype of a structural material with unusual mechanical properties that arise almost exclusively from the geometry of its constituent folds and forms the basis for mechanical metamaterials with an extreme deformation response. Here we consider a simple periodically folded structure Miura-ori, which is composed of identical unit cells of mountain and valley folds with four-coordinated ridges, de?fined completely by 2 angles and 2 lengths. We use the geometrical properties of a Miura-ori plate to characterize its elastic response to planar and non-planar piece- wise isometric deformations and calculate the two-dimensional stretching and bending response of a Miura-ori sheet, and show that the in-plane and out-of-plane Poisson's ratios are equal in magnitude, but opposite in sign. Our geometric approach also allows us to solve the inverse design problem of determining the geometric parameters that achieve the optimal geometric and mechanical response of such structures.
Institute of Scientific and Technical Information of China (English)
WU Denghao; YUAN Shouqi; REN Yun; MU Jiegang; YANG Youdong; LIU Jian
2016-01-01
Improper design of volute geometry can be the main cause that leads to unsteady pressure pulsation and radial force in pumps. Therefore, it is important to understand the influence of volute geometrical parameters on hydrodynamic characteristics of pump and the mechanism. However, the existing studies are limited to investigate the influence of only one or two volute geometrical parameters each time, and a systematic study of the influence of the combinations of different volute geometrical parameters on the pump’s hydrodynamic characteristics is missing. In this paper, a study on the understanding of the influence of volute geometrical variations on hydrodynamic characteristics of a high speed circulator pump by using computational fluid dynamics(CFD) technology is presented. Five main volute geometrical parametersD3,A8,a0,j0 andRt are selected and 25 different volute configurations are generated by using design of experiments(DOE) method. The 3D unsteady flow numerical simulations, which are based on the SSTk-w turbulence model and sliding mesh technique provided by CFX, are executed on the 25 different volute configurations. The hydraulic performance, pressure pulsation and unsteady radial force inside the pump at design condition are obtained and analyzed. It has been found that volute geometrical parametersD3 andA8 are major influence factors on hydrodynamic characteristics of the pump, whilea0,j0 andRt are minor influence factors. The minimum contribution from bothD3 andA8 is 58% on head, and maximum contribution from bothD3 and A8 is 90% on pressure pulsation. Regarding the pressure pulsation intensity, two peaks can be found. One is in the tongue area and the other is in the diffusor area. The contributions are around 60% from tongue and 25% from diffusor, respectively. The amplitude of pressure pulsation has a quadratic polynomial functional relationship with respect toD3/D2 andA8/A10, and fluctuating level of radial force has a quadratic polynomial
Directory of Open Access Journals (Sweden)
Elfar O. M. R.
2016-01-01
Full Text Available In this research, the friction stir welding of dissimilar commercial pure aluminium and brass (CuZn30 plates was investigated and the process parameters were optimized using Taguchi L9 orthogonal array. The considered process parameters were the rotational speed, traverse speed and pin offset. The optimum setting was determined with reference to ultimate tensile strength of the joint. The predicted optimum value of ultimate tensile strength was confirmed by experimental run using optimum parameters. Analysis of variance revealed that traverse speed is the most significant factor in controlling the joint tensile strength and pin offset also plays a significant role. In this investigation, the optimum tensile strength is 50% of aluminium base metal. Metallographic examination revealed that intermetallic compounds were formed in the interface of the optimum joint where the tensile failure was observed to take place.
Ecolifter Conceptual Configuration Design and Parameter Analysis
Institute of Scientific and Technical Information of China (English)
唐胜景
2003-01-01
In the phase of conceptually designing, the Ecolifter with three-lift-surface configuration, the influences of aircraft geometric parameters and configuration such as wing geometric parameters, canard parameters, aircraft center of gravity and engine positions and so on, on flight dynamic stability are discussed with the integrated analysis method. On the basis of the analysis of flight dynamic stability, the suitable wing geometric parameters are given and the improved aircraft configuration is proposed.
Prayogo, Galang Sandy; Lusi, Nuraini
2016-04-01
The optimization technique of machining parameters considering multiple performance characteristics of non conventional machining EDM process using Taguchi method combined with grey relational analysis (GRA) is presented in this study. ST 42 steel was chosen as material work piece and graphite as electrode during this experiment. Performance characteristics such as material removal rate and overcut are selected to evaluated the effect of machining parameters. Current, pulse on time, pulse off time and discharging time/ Z down were selected as machining parameters. The experiments was conducted by varying that machining parameters in three different levels. Based on the Taguchi quality design concept, a L27 orthogonal array table was chosen for the experiments. By using the combination of GRA and Taguchi, the optimization of complicated multiple performance characteristics was transformed into the optimization of a single response performance index. Optimal levels of machining parameters were identified by using Grey Relational Analysis method. The statistical application of analysis of variance was used to determine the relatively significant machining parameters. The result of confirmation test indicted that the determined optimal combination of machining parameters effectively improve the performance characteristics of the machining EDM process on ST 42 steel.
Using hardware-assisted geometric hashing for high-speed target acquisition and guidance
Pears, Arnold N.; Pissaloux, Edwige E.
1997-06-01
Geometric hashing provides a reliable and transformation independent representation of a target. The characterization of a target object is obtained by establishing a vector basis relative to a number of interest points unique to the target. The number of basis points required is a function of the dimensionality of the environment in which the technique is being used. This basis is used to encode the other points in the object constructing a highly general (transformation independent) representation of the target. The representation is invariant under both affine and geometric transformations of the target interest points. Once a representation of the target has been constructed a simple voting algorithm can be used to examine sets of interest points extracted from subsequent image in order to determine the possible presence and location of that target. Once an instance of the object has been located further computation can be undertaken to determine its scale, orientation, and deformation due to changes in the parameters related to the viewpoint. This information can be further analyzed to provide guidance. This paper discusses the complexity measures associated with task division and target image processing using geometric hashing. These measures are used to determine the areas which will most benefit from hardware assistance, and possible parallelism. These issues are discussed in the context of an architecture design, and a high speed (hardware assisted) geometric hashing approach to target recognition is proposed.
Directory of Open Access Journals (Sweden)
Ides K
2012-09-01
Full Text Available Kris Ides,1–3 Wim Vos,3,4 Lieve De Backer,2,3 Dirk Vissers,1,2 Rita Claes,2,3 Glenn Leemans,1,2 Kevin Ongena,1 Oswald Peters,5 Wilfried De Backer1–31Department of Health Science, Artesis University College of Antwerp, Merksem, 2Faculty of Medicine and Health Sciences, University of Antwerp, Wilrijk, 3Department of Respiratory Medicine, Antwerp University Hospital, Edegem, 4FluidDa.nv, Groeningerlei, Kontich, Belgium, 5AZ Monica, Antwerp, BelgiumObjective: Chest physiotherapy enhances sputum evacuation in COPD patients. It can be applied as a single technique or as a combination of techniques including intrapulmonary percussive ventilation (IPV. Recently developed assessment techniques may provide new insights into the effect of airway clearance techniques.Participants: Five moderate to severe COPD patients (three females and two males; mean forced expiratory volume in 1 second of 39.49% predicted who were admitted in the hospital for an acute exacerbation were included in this study.Methods: A novel imaging technique was used, together with other conventional techniques, to visualize the short-term effects of a single IPV treatment in COPD patients.Results: No significant changes were noted in the lung function parameters or arterial blood gases measured within 1 hour after the end of the IPV session. Computed tomography images detected changes in the airway patency after the IPV treatment compared with before treatment. Local resistances, calculated for the three-dimensional models, showed local changes in airway resistance.Conclusion: The effects of a single IPV session can be visualized by functional imaging. This functional imaging allows a calculation of changes in local airway resistance and local changes in airway volume in COPD patients without affecting conventional lung function parameters.Keywords: IPV, lung function, forced oscillation technique, physical therapy, airway clearance technique
Energy Technology Data Exchange (ETDEWEB)
Tunc Aldemir; Don W. Miller; Brian k. Hajek; Peng Wang
2002-04-01
The DSD (Dynamic System Doctor) is a system-independent, interactive software under development for on-line state/parameter estimation in dynamic systems (1), partially supported through a Nuclear Engineering Education (NEER) grant during 1998-2001. This paper summarizes the recent accomplishments in improving the user-friendliness and computational capability of DSD
Harmonic and geometric analysis
Citti, Giovanna; Pérez, Carlos; Sarti, Alessandro; Zhong, Xiao
2015-01-01
This book presents an expanded version of four series of lectures delivered by the authors at the CRM. Harmonic analysis, understood in a broad sense, has a very wide interplay with partial differential equations and in particular with the theory of quasiconformal mappings and its applications. Some areas in which real analysis has been extremely influential are PDE's and geometric analysis. Their foundations and subsequent developments made extensive use of the Calderón–Zygmund theory, especially the Lp inequalities for Calderón–Zygmund operators (Beurling transform and Riesz transform, among others) and the theory of Muckenhoupt weights. The first chapter is an application of harmonic analysis and the Heisenberg group to understanding human vision, while the second and third chapters cover some of the main topics on linear and multilinear harmonic analysis. The last serves as a comprehensive introduction to a deep result from De Giorgi, Moser and Nash on the regularity of elliptic partial differen...
Geometrical approach to fluid models
Kuvshinov, B. N.; Schep, T. J.
1997-01-01
Differential geometry based upon the Cartan calculus of differential forms is applied to investigate invariant properties of equations that describe the motion of continuous media. The main feature of this approach is that physical quantities are treated as geometrical objects. The geometrical
In Defence of Geometrical Algebra
Blasjo, V.N.E.
2016-01-01
The geometrical algebra hypothesis was once the received interpretation of Greek mathematics. In recent decades, however, it has become anathema to many. I give a critical review of all arguments against it and offer a consistent rebuttal case against the modern consensus. Consequently, I find that the geometrical algebra interpretation should be reinstated as a viable historical hypothesis.
Homological Type of Geometric Transitions
Rossi, Michele
2010-01-01
The present paper gives an account and quantifies the change in topology induced by small and type II geometric transitions, by introducing the notion of the \\emph{homological type} of a geometric transition. The obtained results agree with, and go further than, most results and estimates, given to date by several authors, both in mathematical and physical literature.
Geometrical approach to fluid models
Kuvshinov, B. N.; Schep, T. J.
1997-01-01
Differential geometry based upon the Cartan calculus of differential forms is applied to investigate invariant properties of equations that describe the motion of continuous media. The main feature of this approach is that physical quantities are treated as geometrical objects. The geometrical notio
Knowledge-based geometric modeling in construction
DEFF Research Database (Denmark)
Bonev, Martin; Hvam, Lars
2012-01-01
a considerably high amount of their recourses is required for designing and specifying the majority of their product assortment. As design decisions are hereby based on knowledge and experience about behaviour and applicability of construction techniques and materials for a predefined design situation, smart...... tools need to be developed, to support these activities. In order to achieve a higher degree of design automation, this study proposes a framework for using configuration systems within the CAD environment together with suitable geometric modeling techniques on the example of a Danish manufacturer...
ElNady, Khaled; Goda, Ibrahim; Ganghoffer, Jean-François
2016-09-01
The asymptotic homogenization technique is presently developed in the framework of geometrical nonlinearities to derive the large strains effective elastic response of network materials viewed as repetitive beam networks. This works extends the small strains homogenization method developed with special emphasis on textile structures in Goda et al. (J Mech Phys Solids 61(12):2537-2565, 2013). A systematic methodology is established, allowing the prediction of the overall mechanical properties of these structures in the nonlinear regime, reflecting the influence of the geometrical and mechanical micro-parameters of the network structure on the overall response of the chosen equivalent continuum. Internal scale effects of the initially discrete structure are captured by the consideration of a micropolar effective continuum model. Applications to the large strain response of 3D hexagonal lattices and dry textiles exemplify the powerfulness of the proposed method. The effective mechanical responses obtained for different loadings are validated by FE simulations performed over a representative unit cell.
Geometric Programming Problem with Co-Efficients and Exponents Associated with Binary Numbers
Directory of Open Access Journals (Sweden)
A. K. Das
2010-01-01
Full Text Available Geometric programming (GP provides a power tool for solving a variety of optimization problems. In the real world, many applications of geometric programming (GP are engineering design problems in which some of the problem parameters are estimating of actual values. This paper develops a solution procedure to solve nonlinear programming problems using GP technique by splitting the cost coefficients, constraint coefficients and exponents with the help of binary numbers. The equivalent mathematical programming problems are formulated to find their corresponding value of the objective function based on the duality theorem. The ability of calculating the cost coefficients, constraint coefficients and exponents developed in this paper might help lead to more realistic modeling efforts in engineering design areas. Standard nonlinear programming software has been used to solve the proposed optimization problem. Two numerical examples are presented to illustrate the method.
Energy Technology Data Exchange (ETDEWEB)
Kempi, V. [Dept. of Clinical Physiology, Sjukhuset, Oestersund (Sweden)
2007-07-01
Aim: Multivariate statistical methods can be used for objective analysis. The emphasis is on analysing renal function parameters together, not one at a time. The aim is to identify curve parameters useful in making predictions in kidneys with and without renal artery stenosis (RAS). Patients, methods: 68 patients with resistant hypertension were subjected to captopril renography with {sup 99m}Tc-DTPA. Variants of background areas and background subtraction methods were employed. A correction was applied for loss of renal parenchyma. Parameters from time-activity curves and retention curves from deconvolution were calculated. Renal angiography established the presence or absence of RAS. Logistic regression analysis, using age- and kidney size-adjusted models, was performed to assess the capability of renography and deconvolution to differentiate between kidneys with and without RAS. Results: Discrimination between normal kidneys and RAS was achieved by deconvolution and by renography. Deconvolution was the method of first rank with a sensitivity of 87% and a specificity of 98%. For separation of RAS and kidneys with parenchymal insufficiency deconvolution was the method of first rank with a sensitivity of 80% and specificity of 89%, whereas renography produced poor results. Conclusion: The best performance with {sup 99m}Tc-DTPA was based on normalised background subtraction using a rectangular area between the kidneys. Deconvolution produced the most favourable results in the separation of kidneys with and without RAS. For separation of RAS and kidneys with parenchymal insufficiency conventional renography produced poor results. Conceptually, the results of a logistic regression analysis of renal function parameters may raise possibilities in the field of computer-aided diagnosis. (orig.)
Auto-focusing accelerating hyper-geometric laser beams
Kovalev, A. A.; Kotlyar, V. V.; Porfirev, A. P.
2016-02-01
We derive a new solution to the paraxial wave equation that defines a two-parameter family of three-dimensional structurally stable vortex annular auto-focusing hyper-geometric (AH) beams, with their complex amplitude expressed via a degenerate hyper-geometric function. The AH beams are found to carry an orbital angular momentum and be auto-focusing, propagating on an accelerating path toward a focus, where the annular intensity pattern is ‘sharply’ reduced in diameter. An explicit expression for the complex amplitude of vortex annular auto-focusing hyper-geometric-Gaussian beams is derived. The experiment has been shown to be in good agreement with theory.
Influence of Bipartite Qubit Coupling on Geometric Phase
Institute of Scientific and Technical Information of China (English)
XING Lei; LIANG Mai-Lin
2006-01-01
The geometric phase of the bipartite Heisenberg spin-1/2 system with one spin driven by rotating magnetic field is investigated. It is found that in the one-site drive case, the intersubsystem coupling can be equivalent to a static quasi-magnetic field in the parameter space. This perspective has satisfactorily explained the irregular asymptote effect of geometric phase. We discuss the property of the two-site magnetic drive spin system and discover that a stationary state with no geometric phase shift is generated.
Geometric calibration for a SPECT system dedicated to breast imaging
Institute of Scientific and Technical Information of China (English)
WU Li-Wei; WEI Long; CAO Xue-Xiang; WANG Lu; HUANG Xian-Chao; CHAI Pei; YUN Ming-Kai; ZHANG Yu-Bao; ZHANG Long; SHAN Bao-Ci
2012-01-01
Geometric calibration is critical to the accurate SPECT reconstruction.In this paper,a geometric calibration method was developed for a dedicated breast SPECT system with a tilted parallel beam (TPB)orbit.The acquisition geometry of the breast SPECT was firstly characterized.And then its projection model was established based on the acquisition geometry.Finally,the calibration results were obtained using a nonlinear optimization method that fitted the measured projections to the model.Monte Carlo data of the breast SPECT were used to verify the calibration method.Simulation results showed that the geometric parameters with reasonable accuracy could be obtained by the proposed method.
Geometrical optics approximation of light scattering by large air bubbles
Institute of Scientific and Technical Information of China (English)
Haitao Yu; Jianqi Shen; Yuehuan Wei
2008-01-01
For large spherical bubbles in water,geometrical optics approximation is considered a better method for calculating light scattering patterns.In this paper,the basic theory of geometrical optics approximation is clarified.The change of phase for bubbles is calculated when total reflection occurs,which is different from particles with relative refractive indices larger than 1.Verification of the method was achieved by assuming a spherical particle and comparing present results to Mie scattering and Debye calculation.Agreement with the Mie theory was excellent in all directions when the dimensionless size parameter is larger than 50.Limitations of the geometrical optics approximation are also discussed.
Theoretical discussions on the geometrical phase analysis
Energy Technology Data Exchange (ETDEWEB)
Rouviere, J.L. [CEA-Grenoble, Departement de Recherche Fondamentale sur la Matiere Condensee, SP2M, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)]. E-mail: rouvierej@cea.fr; Sarigiannidou, E. [CEA-Grenoble, Departement de Recherche Fondamentale sur la Matiere Condensee, SP2M, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)
2005-12-15
The Geometrical phase analysis, which is a very efficient method to measure deformation from High resolution transmission electron microscopy images, is studied from a theoretical point of view. We point out that the basic property of this method is its ability to measure local reciprocal lattice parameters with a high level of accuracy. We attempt to provide some insights into (a) different formula used in the geometrical phase analysis such as the well-known relation between phase and displacement: P{sub g}(r)=-2{pi}g.u(r), (b) the two different definitions of strain, each of which corresponding to a different lattice reference and (c) the meaning of a continuous displacement in a dot-like high resolution image. The case of one-dimensional analysis is also presented. Finally, we show that the method is able to give the position of the dot that is nearest to a given pixel in the image.
Geometric Programming Approach to an Interactive Fuzzy Inventory Problem
Directory of Open Access Journals (Sweden)
Nirmal Kumar Mandal
2011-01-01
Full Text Available An interactive multiobjective fuzzy inventory problem with two resource constraints is presented in this paper. The cost parameters and index parameters, the storage space, the budgetary cost, and the objective and constraint goals are imprecise in nature. These parameters and objective goals are quantified by linear/nonlinear membership functions. A compromise solution is obtained by geometric programming method. If the decision maker is not satisfied with this result, he/she may try to update the current solution to his/her satisfactory solution. In this way we implement man-machine interactive procedure to solve the problem through geometric programming method.
Directory of Open Access Journals (Sweden)
Robert Hernández-Ortega
2012-12-01
Full Text Available Este trabajo tuvo como objetivo obtener un procedimiento, que al implementarse en un software para el diseño de transmisiones por engranajes cilíndricos con contacto exterior, correlacione automáticamente los parámetros geométricos mediante los contornos de bloqueo y así facilitar el trabajo del diseñador deengranajes. Para ello, se transformaron las expresiones matemáticas que definen las limitaciones geométricas para que puedan ser utilizadas en un programa que construya el contorno de bloqueo sin la intervención del diseñador. Se estableció además la secuencia en que estas deben ser calculadas. El procedimiento obtenido se implementó en un programa de computación obteniéndose una velocidad deejecución de 1 segundo aproximadamente. De esta forma se logró la correlación automática de los parámetros geométricos y un contorno de bloqueo que muestra el conjunto de valores de los coeficientes de corrección de las ruedas que pueden ser utilizados, construidos sin interacción con el diseñador.Palabras claves: contorno de bloqueo, engranajes, parámetros geométricos._______________________________________________________________________________AbstractThe aim of this work was to obtain a procedure, that when being implemented in the design software of spur and helical external gears, correlate the geometric parameters automatically by means of the blocking contours making easier the designer's work. The mathematical expressions that define the geometriclimitations were transformed so that they can be used in a program that it builds the blocking contour without the designer's intervention. Besides that it was settled down the sequence they should be calculated. The procedure was implemented in a calculation program obtaining an execution speed about 1 second. This way it was achieved the automatic correlation of the geometric parameters and a blockingcontour construction without the designer's intervention that it shows the
Directory of Open Access Journals (Sweden)
J. Randulfe Ceballos
2001-10-01
Full Text Available En la industria mecánica, uno de los elementos más utilizados son las transmisiones de ruedas dentadas. Estos elementos demáquinas con el trabajo prolongado, sufren cambios notables en su geometría original, debido principalmente a las cargas aque están sometidos. Para reacondicionar estas ruedas, es imprescindible conocer los parámetros geométricos originalespara poder maquinar. Cuando se desconoce esta información, es necesario determinarla, y precisamente éste es elcontenido del trabajo, la determinación de los parámetros geométricos originales de ruedas cilíndricas de dientes rectos yhelicoidales, a partir de mediciones realizadas a parámetros de la transmisión, que posteriormente son introducidos comodatos, en un programa de computación. En pocos segundos se obtienen los valores necesarios para la fabricación de lasruedas, obteniéndose valores mucho más precisos que utilizando los métodos tradicionales que se emplean en las empresasque se dedican a esta funciónPalabras claves: Ruedas dentadas helicoidales, cálculos, parámetros geométricos, automatización._________________________________________________________________Abstract:In the mechanical industry, one of the most used elements are gears transmissions. These machine elements under longexploitation term, suffer remarkable changes in their original geometry due principally to the working loads. In order torecondition these wheels it is indispensable to know the original geometric parameters in order to be able to mechanize newones. When this information is unknown it is necessary to determine it, and in fact this is the content of this paper, startingfrom mensurations of transmission parameters carried out and later and introduced as data in a computation program. Enfew seconds the necessary values for the production of gears are obtained with much more precise values than using thetraditional methods in use by companies that are devoted to this function
Geometrical method of decoupling
Baumgarten, C.
2012-12-01
The computation of tunes and matched beam distributions are essential steps in the analysis of circular accelerators. If certain symmetries—like midplane symmetry—are present, then it is possible to treat the betatron motion in the horizontal, the vertical plane, and (under certain circumstances) the longitudinal motion separately using the well-known Courant-Snyder theory, or to apply transformations that have been described previously as, for instance, the method of Teng and Edwards. In a preceding paper, it has been shown that this method requires a modification for the treatment of isochronous cyclotrons with non-negligible space charge forces. Unfortunately, the modification was numerically not as stable as desired and it was still unclear, if the extension would work for all conceivable cases. Hence, a systematic derivation of a more general treatment seemed advisable. In a second paper, the author suggested the use of real Dirac matrices as basic tools for coupled linear optics and gave a straightforward recipe to decouple positive definite Hamiltonians with imaginary eigenvalues. In this article this method is generalized and simplified in order to formulate a straightforward method to decouple Hamiltonian matrices with eigenvalues on the real and the imaginary axis. The decoupling of symplectic matrices which are exponentials of such Hamiltonian matrices can be deduced from this in a few steps. It is shown that this algebraic decoupling is closely related to a geometric “decoupling” by the orthogonalization of the vectors E→, B→, and P→, which were introduced with the so-called “electromechanical equivalence.” A mathematical analysis of the problem can be traced down to the task of finding a structure-preserving block diagonalization of symplectic or Hamiltonian matrices. Structure preservation means in this context that the (sequence of) transformations must be symplectic and hence canonical. When used iteratively, the decoupling
Geometric Deep Learning: Going beyond Euclidean data
Bronstein, Michael M.; Bruna, Joan; LeCun, Yann; Szlam, Arthur; Vandergheynst, Pierre
2017-07-01
Many scientific fields study data with an underlying structure that is a non-Euclidean space. Some examples include social networks in computational social sciences, sensor networks in communications, functional networks in brain imaging, regulatory networks in genetics, and meshed surfaces in computer graphics. In many applications, such geometric data are large and complex (in the case of social networks, on the scale of billions), and are natural targets for machine learning techniques. In particular, we would like to use deep neural networks, which have recently proven to be powerful tools for a broad range of problems from computer vision, natural language processing, and audio analysis. However, these tools have been most successful on data with an underlying Euclidean or grid-like structure, and in cases where the invariances of these structures are built into networks used to model them. Geometric deep learning is an umbrella term for emerging techniques attempting to generalize (structured) deep neural models to non-Euclidean domains such as graphs and manifolds. The purpose of this paper is to overview different examples of geometric deep learning problems and present available solutions, key difficulties, applications, and future research directions in this nascent field.
Geometric Properties of QCD string from Willmore Functional
Parthasarathy, R
2001-01-01
The extremum of the Willmore-like functional for $m$-dimensional Riemannian surface immersed in $d$-dimensional Riemannian manifold under normal variations is studied and various cases of interest are examined. This study is used to relate the parameters of QCD string action, including the Polyakov-Kleinert extrinsic curvature action, with the geometric properties of the world sheet. The world sheet has been shown to have {\\it{negative stiffness} on the basis of geometric considerations.
Institute of Scientific and Technical Information of China (English)
ZHAO Bao-fu
2001-01-01
Based on the fundamental simulation theories and methods, this paper studies such questions as truck dispatching, discrete processing of belt system continuous haulage, belt system interlock, and economic assessment methods. On the basis of above studies, the paper establishes a simulation model for open-p i t mine semi-continuous production technique system. The paper applies GPSS lang u age to construct a simulation program, and the program has been successfully app lied in a certain coalmine.
Arunachalam, M. S.; Puli, Anil; Anuradha, B.
2016-07-01
In the present work continuous extraction of convective cloud optical information and reflectivity (MAX(Z) in dBZ) using online retrieval technique for time series data production from Doppler Weather Radar (DWR) located at Indian Meteorological Department, Chennai has been developed in MATLAB. Reflectivity measurements for different locations within the DWR range of 250 Km radii of circular disc area can be retrieved using this technique. It gives both time series reflectivity of point location and also Range Time Intensity (RTI) maps of reflectivity for the corresponding location. The Graphical User Interface (GUI) developed for the cloud reflectivity is user friendly; it also provides the convective cloud optical information such as cloud base height (CBH), cloud top height (CTH) and cloud optical depth (COD). This technique is also applicable for retrieving other DWR products such as Plan Position Indicator (Z, in dBZ), Plan Position Indicator (Z, in dBZ)-Close Range, Volume Velocity Processing (V, in knots), Plan Position Indicator (V, in m/s), Surface Rainfall Intensity (SRI, mm/hr), Precipitation Accumulation (PAC) 24 hrs at 0300UTC. Keywords: Reflectivity, cloud top height, cloud base, cloud optical depth
Whyms, B.J.; Vorperian, H.K.; Gentry, L.R.; Schimek, E.M.; Bersu, E.T.; Chung, M.K.
2013-01-01
Objectives This study investigates the effect of scanning parameters on the accuracy of measurements from three-dimensional multi-detector computed tomography (3D-CT) mandible renderings. A broader range of acceptable parameters can increase the availability of CT studies for retrospective analysis. Study Design Three human mandibles and a phantom object were scanned using 18 combinations of slice thickness, field of view, and reconstruction algorithm and three different threshold-based segmentations. Measurements of 3D-CT models and specimens were compared. Results Linear and angular measurements were accurate, irrespective of scanner parameters or rendering technique. Volume measurements were accurate with a slice thickness of 1.25 mm, but not 2.5 mm. Surface area measurements were consistently inflated. Conclusions Linear, angular and volumetric measurements of mandible 3D-CT models can be confidently obtained from a range of parameters and rendering techniques. Slice thickness is the primary factor affecting volume measurements. These findings should also apply to 3D rendering using cone-beam-CT. PMID:23601224
Woodrow, Kathryn; Lindsay, John B.; Berg, Aaron A.
2016-09-01
Although digital elevation models (DEMs) prove useful for a number of hydrological applications, they are often the end result of numerous processing steps that each contains uncertainty. These uncertainties have the potential to greatly influence DEM quality and to further propagate to DEM-derived attributes including derived surface and near-surface drainage patterns. This research examines the impacts of DEM grid resolution, elevation source data, and conditioning techniques on the spatial and statistical distribution of field-scale hydrological attributes for a 12,000 ha watershed of an agricultural area within southwestern Ontario, Canada. Three conditioning techniques, including depression filling (DF), depression breaching (DB), and stream burning (SB), were examined. The catchments draining to each boundary of 7933 agricultural fields were delineated using the surface drainage patterns modeled from LiDAR data, interpolated to a 1 m, 5 m, and 10 m resolution DEMs, and from a 10 m resolution photogrammetric DEM. The results showed that variation in DEM grid resolution resulted in significant differences in the spatial and statistical distributions of contributing areas and the distributions of downslope flowpath length. Degrading the grid resolution of the LiDAR data from 1 m to 10 m resulted in a disagreement in mapped contributing areas of between 29.4% and 37.3% of the study area, depending on the DEM conditioning technique. The disagreements among the field-scale contributing areas mapped from the 10 m LiDAR DEM and photogrammetric DEM were large, with nearly half of the study area draining to alternate field boundaries. Differences in derived contributing areas and flowpaths among various conditioning techniques increased substantially at finer grid resolutions, with the largest disagreement among mapped contributing areas occurring between the 1 m resolution DB DEM and the SB DEM (37% disagreement) and the DB-DF comparison (36.5% disagreement in mapped
Geometric covering arguments and ergodic theorems for free groups
Bowen, Lewis
2009-01-01
We present a new approach to the proof of ergodic theorems for actions of free groups based on geometric covering and asymptotic invariance arguments. Our approach can be viewed as a direct generalization of the classical geometric covering and asymptotic invariance arguments used in the ergodic theory of amenable groups. We use this approach to generalize the existing maximal and pointwise ergodic theorems for free group actions to a large class of geometric averages which were not accessible by previous techniques. Some applications of our approach to other groups and other problems in ergodic theory are also briefly discussed.
Institute of Scientific and Technical Information of China (English)
李文凯; 张勃; 吉洪湖; 陆海鹰; 邓明春; 杨晓明
2015-01-01
The models of the straight-through labyrinth seals with different geometry parameters were designed,The ge-ometry parameters studied include seal clearance,fin number,fin pitch,fin height and fin tip thickness.The effect of geom-etry parameters on the sealing characteristics of the straight-through labyrinth seals were investigated numerically at differ-ent drop pressure ratios(the ratio of inlet and outlet pressure).The results show that the discharge coefficient is increased with the increasing of the drop pressure ratio,the seal clearance and the fin tip thickness,and decreased with the increasing of the fin height,the fin pitch and the fin number.The effect of seal clearance on the sealing characteristics is the maxi-mum,the following is fin number,fin pitch,fin height and fin tip thickness.The correlation formula of discharge coefficient about these parameters was fitted by the method of least squares.The calculation results of the fitted formula are in good a-greement with those obtained from numerical simulation,it can be used for the engineering design and calculation the laby-rinth seals.%建立不同封严间隙、齿高、齿距、齿宽、齿数等几何参数的直通篦齿模型，通过数值方法分析不同气动参数（进出口落压比）条件下几何参数变化对其泄漏特性的影响。结果表明，流量系数随落压比的增大而增大，随着封严间隙、齿宽的增大而增大，随着齿高、齿距、齿数的增大而减小。5个几何参数中，封严间隙对流量系数的影响最大，其次为齿数、齿距、齿高、齿宽。利用最小二乘法拟合得到流量系数与几何参数及气动参数的准则关系式，拟合公式计算结果与数值模拟结果吻合较好，可用于篦齿的工程设计计算。
A Video Watermarking Against Geometrical Distortions
Institute of Scientific and Technical Information of China (English)
NIUXiamu; SCHMUCKERMartin; BUSCHChristoph; SUNShenghe
2003-01-01
A video watermarking with robustness against frame's geometrical distortions (rotation, aspect ratio, scaling, translation shearing, and bending) is proposed. The watermark information is embedded into pixels along the temporal axis within a Watermark minimum segment (WMS). Since the geometrical distortions operations for every frame along the time axis in a video sequence are the same at a very short interval, the watermark information can be detected from watermarked frames in each WMS subjected to the distortions. Furthermore, adaptive embedding method is proposed for gaining a good quality of the watermarked video. Experimental results show that the proposed technique is robust against common attacks such as rotation, aspect ratio, scaling, translation shearing, and bending of frames, MPEG-2 lossy compression, and color-space conversion.
Geometrical multiresolution adaptive transforms theory and applications
Lisowska, Agnieszka
2014-01-01
Modern image processing techniques are based on multiresolution geometrical methods of image representation. These methods are efficient in sparse approximation of digital images. There is a wide family of functions called simply ‘X-lets’, and these methods can be divided into two groups: the adaptive and the nonadaptive. This book is devoted to the adaptive methods of image approximation, especially to multismoothlets. Besides multismoothlets, several other new ideas are also covered. Current literature considers the black and white images with smooth horizon function as the model for sparse approximation but here, the class of blurred multihorizon is introduced, which is then used in the approximation of images with multiedges. Additionally, the semi-anisotropic model of multiedge representation, the introduction of the shift invariant multismoothlet transform and sliding multismoothlets are also covered. Geometrical Multiresolution Adaptive Transforms should be accessible to both mathematicians and com...
Color fringe projection profilometry using geometric constraints
Cheng, Teng; Du, Qingyu; Jiang, Yaxi
2017-09-01
A recently proposed phase unwrapping method using geometric constraints performs well without requiring additional camera, more patterns or global search. The major limitation of this technique is the confined measurement depth range (MDR) within 2π in phase domain. To enlarge the MDR, this paper proposes using color fringes for three-dimensional (3D) shape measurement. Each six fringe periods encoded with six different colors are treated as one group. The local order within one group can be identified with reference to the color distribution. Then the phase wrapped period-by-period is converted into the phase wrapped group-by-group. The geometric constraints of the fringe projection system are used to determine the group order. Such that the MDR is extended from 2π to 12π by six times. Experiment results demonstrate the success of the proposed method to measure two isolated objects with large MDR.
Zubarev, A. E.; Nadezhdina, I. E.; Brusnikin, E. S.; Karachevtseva, I. P.; Oberst, J.
2016-09-01
The new technique for generation of coordinate control point networks based on photogrammetric processing of heterogeneous planetary images (obtained at different time, scale, with different illumination or oblique view) is developed. The technique is verified with the example for processing the heterogeneous information obtained by remote sensing of Ganymede by the spacecraft Voyager-1, -2 and Galileo. Using this technique the first 3D control point network for Ganymede is formed: the error of the altitude coordinates obtained as a result of adjustment is less than 5 km. The new control point network makes it possible to obtain basic geodesic parameters of the body (axes size) and to estimate forced librations. On the basis of the control point network, digital terrain models (DTMs) with different resolutions are generated and used for mapping the surface of Ganymede with different levels of detail (Zubarev et al., 2015b).
Nonadiabatic Geometric Phase in Composite Systems and Its Subsystem
Institute of Scientific and Technical Information of China (English)
LI Xin
2008-01-01
We point out that the time-dependent gauge transformation technique may be effective in investigating the nonadiabatic geometric phase of a subsystem in a composite system. As an example, we consider two uniaxially coupled spin -1/2 particles with one of particles driven by rotating magnetic field. The influences of coupling and precession frequency of the magnetic field on geometric phase are also discussed in detail.
Applications of geometrical criteria for transition to Hamiltonian chaos.
Ben Zion, Yossi; Horwitz, Lawrence
2008-09-01
Using a recently developed geometrical method, we study the transition from order to chaos in an important class of Hamiltonian systems. We show agreement between this geometrical method and the surface of section technique applied to detect chaotic behavior. We give, as a particular illustration, detailed results for an important class of potentials obtained from the perturbation of an oscillator Hamiltonian by means of higher-order polynomials.
Some hyperbolic three-manifolds that bound geometrically
KOLPAKOV, Alexander; Martelli, Bruno; Tschantz, Steven
2015-01-01
A closed connected hyperbolic $n$-manifold bounds geometrically if it is isometric to the geodesic boundary of a compact hyperbolic $(n+1)$-manifold. A. Reid and D. Long have shown by arithmetic methods the existence of infinitely many manifolds that bound geometrically in every dimension. We construct here infinitely many explicit examples in dimension $n=3$ using right-angled dodecahedra and $120$-cells and a simple colouring technique introduced by M. Davis and T. Januszkiewicz. Namely, fo...
Geometrical method of decoupling
Directory of Open Access Journals (Sweden)
C. Baumgarten
2012-12-01
Full Text Available The computation of tunes and matched beam distributions are essential steps in the analysis of circular accelerators. If certain symmetries—like midplane symmetry—are present, then it is possible to treat the betatron motion in the horizontal, the vertical plane, and (under certain circumstances the longitudinal motion separately using the well-known Courant-Snyder theory, or to apply transformations that have been described previously as, for instance, the method of Teng and Edwards. In a preceding paper, it has been shown that this method requires a modification for the treatment of isochronous cyclotrons with non-negligible space charge forces. Unfortunately, the modification was numerically not as stable as desired and it was still unclear, if the extension would work for all conceivable cases. Hence, a systematic derivation of a more general treatment seemed advisable. In a second paper, the author suggested the use of real Dirac matrices as basic tools for coupled linear optics and gave a straightforward recipe to decouple positive definite Hamiltonians with imaginary eigenvalues. In this article this method is generalized and simplified in order to formulate a straightforward method to decouple Hamiltonian matrices with eigenvalues on the real and the imaginary axis. The decoupling of symplectic matrices which are exponentials of such Hamiltonian matrices can be deduced from this in a few steps. It is shown that this algebraic decoupling is closely related to a geometric “decoupling” by the orthogonalization of the vectors E[over →], B[over →], and P[over →], which were introduced with the so-called “electromechanical equivalence.” A mathematical analysis of the problem can be traced down to the task of finding a structure-preserving block diagonalization of symplectic or Hamiltonian matrices. Structure preservation means in this context that the (sequence of transformations must be symplectic and hence canonical. When
Geometric Computing for Freeform Architecture
Wallner, J.
2011-06-03
Geometric computing has recently found a new field of applications, namely the various geometric problems which lie at the heart of rationalization and construction-aware design processes of freeform architecture. We report on our work in this area, dealing with meshes with planar faces and meshes which allow multilayer constructions (which is related to discrete surfaces and their curvatures), triangles meshes with circle-packing properties (which is related to conformal uniformization), and with the paneling problem. We emphasize the combination of numerical optimization and geometric knowledge.
Tomaszewska, Ewa; Dobrowolski, Piotr; Winiarska-Mieczan, Anna; Kwiecień, Małgorzata; Tomczyk, Agnieszka; Muszyński, Siemowit; Radzki, Radosław
2016-09-01
Adolescent male Wistar rats were used to check whether regular consumption of black, red, white, or green tea would have a protective effect on femur development during 12-week exposure to Cd and Pb (7mg Cd and 50mg Pb in 1kg of the diet). The animals were randomly divided (n=12) into a positive control (without Cd, Pb and teas), a negative control group (Cd and Pb), and groups supplemented additionally with green (GT), black (BT), red (RT), and white tea (WT). Heavy metals reduced the geometric and densitometric parameters and the total thickness of articular cartilage irrespective of tea administration and influenced mechanical endurance, growth plate thickness, and trabecular histomorphometry depending on the tea type. It is difficult to indicate which tea has the best protective effects on bone and hyaline cartilage against heavy metal action.
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
Surface composite up to 3.0 mm in thickness with compact microstructure was fabricated successfully via vacuum infiltration casting technique on the bronze substrate under the optimum experimental conditions: the vacuum degree of -0.08 MPa, pouring temperature of 1220℃, grain size of 0. 20-0. 24 mm, preheating temperature of 180℃. The preform was mainly composed of graphite particles and binder NJB (self-fabricated binder). The vacuum degree, pouring temperature, preheating temperature and grain size during infiltration casting play an important role on the process of forming the surface composite. The results show that three cases are obtained in the vacuum infiltration casting technique: no infiltration, partial infiltration and full infiltration. The main reason of no infiltration is that the vacuum degree is not enough so that the force acting on the liquid metal is lower than the resistance due to the surface tension and the pouring temperature is somewhat low. Partial infiltration is because of somewhat lower vacuum degree and pouring temperature. Full desired infiltration is on account of suitable infiltration casting conditions, such as vacuum degree, pouring temperature, grain size and preheating temperature. The influencing effect of vacuum degree is most obvious for the formation of surface composite, then pouring temperature and particle size. The infiltration mechanism is discussed on the bases of the different processing conditions.
3D IMAGE BASED GEOMETRIC DOCUMENTATION OF THE TOWER OF WINDS
Directory of Open Access Journals (Sweden)
M. S. Tryfona
2016-06-01
Full Text Available This paper describes and investigates the implementation of almost entirely image based contemporary techniques for the three dimensional geometric documentation of the Tower of the Winds in Athens, which is a unique and very special monument of the Roman era. These techniques and related algorithms were implemented using a well-known piece of commercial software with extreme caution in the selection of the various parameters. Problems related to data acquisition and processing, but also to the algorithms and to the software implementation are identified and discussed. The resulting point cloud has been georeferenced, i.e. referenced to a local Cartesian coordinate system through minimum geodetic measurements, and subsequently the surface, i.e. the mesh was created and finally the three dimensional textured model was produced. In this way, the geometric documentation drawings, i.e. the horizontal section plans, the vertical section plans and the elevations, which include orthophotos of the monument, can be produced at will from that 3D model, for the complete geometric documentation. Finally, a 3D tour of the Tower of the Winds has also been created for a more integrated view of the monument. The results are presented and are evaluated for their completeness, efficiency, accuracy and ease of production.
Moldovan, Oana; Castro-Carranza, Alejandra; Cerdeira, Antonio; Estrada, Magali; Barquinha, Pedro; Martins, Rodrigo; Fortunato, Elvira; Miljakovic, Slobodan; Iñiguez, Benjamin
2016-12-01
An advanced compact and analytical drain current model for the amorphous gallium indium zinc oxide (GIZO) thin film transistors (TFTs) is proposed. Its output saturation behavior is improved by introducing a new asymptotic function. All model parameters were extracted using an adapted version of the Universal Method and Extraction Procedure (UMEM) applied for the first time for GIZO devices in a simple and direct form. We demonstrate the correct behavior of the model for negative VDS, a necessity for a complete compact model. In this way we prove the symmetry of source and drain electrodes and extend the range of applications to both signs of VDS. The model, in Verilog-A code, is implemented in Electronic Design Automation (EDA) tools, such as Smart Spice, and compared with measurements of TFTs. It describes accurately the experimental characteristics in the whole range of GIZO TFTs operation, making the model suitable for the design of circuits using these types of devices.
Institute of Scientific and Technical Information of China (English)
杨欣建; 王正国; 朱佩芳; 宁心; 郭小愚; 陈海斌
2004-01-01
目的:探讨胸腰段脊柱节段撞击能量与几何参数、几何参数变化与生物力学的相互关系,为评判脊柱损伤程度及稳定性变化提供相应的客观标准,为治疗中采取适宜的生物力学方法提供确切的实验依据. 方法:对 18例新鲜尸体胸腰段脊柱标本进行不同能量的撞击,复制成不同损伤程度的 L1椎体爆裂骨折模型.结合脊柱三维稳定性测试,进行椎体几何参数及生物力学分析. 结果:低能量撞击使节段出现结构"松弛"的现象,椎体几何参数仅角度参数部分出现变化( P< 0.05),表明椎间松弛、椎体无明显破坏.中、高能量撞击使椎体几何参数发生明显变化,中能量组后伸位时前椎体高( AVH)、畸形率 (DR)可基本恢复正常,而后椎体高 (PVH)和椎体直径 (VD)不能恢复正常( P< 0.05);高能量组 AVH和 DR后伸时也可恢复到正常,然而, PVH和 VD与正常相差更加明显( P< 0.01).牵伸作用后,中、高能量组除 VD外,其余线性和角度参数都能基本恢复至正常,表明牵伸能使椎体得到较好复位. 结论: AVH、 DR和角度参数可作为判断脊柱稳定性的指标;而 PVH、后单位高( PUH)不到正常的 85%时,预示着损伤节段结构的严重破坏,为重度爆裂粉碎骨折.牵伸力是满足椎体几何参数恢复的有效生物力学方法.重度爆裂骨折的后伸复位也有一定的危险性.%AIM: To explore the relationship between the different levels of impact energy and geometric parameters,variations of such parameters and their biomechanics to provide an objective standard for evaluation of the extent of injury to the spine and the stability variations and to provide an accurate experimental basis for selecting a proper biomechanical management method in handling such injuries.METHODS: Eighteen human thoracolumbar spines taken from cadavers were impacted with different levels of energy.Then,models of L1 vertebrae burst injuries of different levels
DEFF Research Database (Denmark)
2011-01-01
of optimisation techniques coupled with dynamic solution of the underlying model. Linear and nonlinear approaches to parameter estimation are investigated. There is also the application of maximum likelihood principles in the estimation of parameters, as well as the use of orthogonal collocation to generate a set......In this chapter the importance of parameter estimation in model development is illustrated through various applications related to reaction systems. In particular, rate constants in a reaction system are obtained through parameter estimation methods. These approaches often require the application...... of algebraic equations as the basis for parameter estimation.These approaches are illustrated using estimations of kinetic constants from reaction system models....
Cerutti, Sergio; Esposti, Federico; Ferrario, Manuela; Sassi, Roberto; Signorini, Maria Gabriella
2007-03-01
Over the last two decades, a large number of different methods had been used to study the fractal-like behavior of the heart rate variability (HRV). In this paper some of the most used techniques were reviewed. In particular, the focus is set on those methods which characterize the long memory behavior of time series (in particular, periodogram, detrended fluctuation analysis, rescale range analysis, scaled window variance, Higuchi dimension, wavelet-transform modulus maxima, and generalized structure functions). The performances of the different techniques were tested on simulated self-similar noises (fBm and fGn) for values of α, the slope of the spectral density for very small frequency, ranging from -1 to 3 with a 0.05 step. The check was performed using the scaling relationships between the various indices. DFA and periodogram showed the smallest mean square error from the expected values in the range of interest for HRV. Building on the results obtained from these tests, the effective ability of the different methods in discriminating different populations of patients from RR series derived from Holter recordings, was assessed. To this extent, the Noltisalis database was used. It consists of a set of 30, 24-h Holter recordings collected from healthy subjects, patients suffering from congestive heart failure, and heart transplanted patients. All the methods, with the exception at most of rescale range analysis, were almost equivalent in distinguish between the three groups of patients. Finally, the scaling relationships, valid for fBm and fGn, when empirically used on HRV series, also approximately held.
Biswas, A.
2016-12-01
A proficient way to deal with appraisal model parameters from total gradient of gravity and magnetic data in light of Very Fast Simulated Annealing (VFSA) has been exhibited. This is the first run through of applying VFSA in deciphering total gradient of potential field information with another detailing estimation brought on because of detached causative sources installed in the subsurface. The model parameters translated here are the amplitude coefficient (k), accurate origin of causative source (x0) depth (z0) and the shape factor (q). The outcome of VFSA improvement demonstrates that it can exceptionally decide all the model parameters when shape variable is fixed. The model parameters assessed by the present strategy, for the most part the shape and depth of the covered structures was observed to be in astounding concurrence with the genuine parameters. The technique has likewise the capability of dodging very uproarious information focuses and enhances the understanding results. Investigation of Histogram and cross-plot examination likewise proposes the translation inside the assessed ambiguity. Inversion of noise-free and noisy synthetic data information for single structures and field information shows the viability of the methodology. The procedure has been carefully and adequately connected to genuine field cases (Leona Anomaly, Senegal for gravity and Pima copper deposit, USA for magnetic) with the nearness of mineral bodies. The present technique can be to a great degree material for mineral investigation or ore bodies of dyke-like structure rooted in the shallow and more deep subsurface. The calculation time for the entire procedure is short.
Mobile Watermarking against Geometrical Distortions
Directory of Open Access Journals (Sweden)
Jing Zhang
2015-08-01
Full Text Available Mobile watermarking robust to geometrical distortions is still a great challenge. In mobile watermarking, efficient computation is necessary because mobile devices have very limited resources due to power consumption. In this paper, we propose a low-complexity geometrically resilient watermarking approach based on the optimal tradeoff circular harmonic function (OTCHF correlation filter and the minimum average correlation energy Mellin radial harmonic (MACE-MRH correlation filter. By the rotation, translation and scale tolerance properties of the two kinds of filter, the proposed watermark detector can be robust to geometrical attacks. The embedded watermark is weighted by a perceptual mask which matches very well with the properties of the human visual system. Before correlation, a whitening process is utilized to improve watermark detection reliability. Experimental results demonstrate that the proposed watermarking approach is computationally efficient and robust to geometrical distortions.
Geometric structure of gauge theories
Energy Technology Data Exchange (ETDEWEB)
Mangiarotti, L.; Modugno, M.
1985-06-01
In the framework of the adjoint forms over the jet spaces of connections and using a canonical jet shift differential, we give a geometrical interpretation of the Yang--Mills equations both in a direct and Lagrangian formulation.
DEFF Research Database (Denmark)
Sales-Cruz, Mauricio; Heitzig, Martina; Cameron, Ian;
2011-01-01
of optimisation techniques coupled with dynamic solution of the underlying model. Linear and nonlinear approaches to parameter estimation are investigated. There is also the application of maximum likelihood principles in the estimation of parameters, as well as the use of orthogonal collocation to generate a set...
Geometric phases in graphitic cones
Energy Technology Data Exchange (ETDEWEB)
Furtado, Claudio [Departamento de Fisica, CCEN, Universidade Federal da Paraiba, Cidade Universitaria, 58051-970 Joao Pessoa, PB (Brazil)], E-mail: furtado@fisica.ufpb.br; Moraes, Fernando [Departamento de Fisica, CCEN, Universidade Federal da Paraiba, Cidade Universitaria, 58051-970 Joao Pessoa, PB (Brazil); Carvalho, A.M. de M [Departamento de Fisica, Universidade Estadual de Feira de Santana, BR116-Norte, Km 3, 44031-460 Feira de Santana, BA (Brazil)
2008-08-04
In this Letter we use a geometric approach to study geometric phases in graphitic cones. The spinor that describes the low energy states near the Fermi energy acquires a phase when transported around the apex of the cone, as found by a holonomy transformation. This topological result can be viewed as an analogue of the Aharonov-Bohm effect. The topological analysis is extended to a system with n cones, whose resulting configuration is described by an effective defect00.
Determining Geometric Accuracy in Turning
Institute of Scientific and Technical Information of China (English)
Kwong; Chi; Kit; A; Geddam
2002-01-01
Mechanical components machined to high levels of ac cu racy are vital to achieve various functional requirements in engineering product s. In particular, the geometric accuracy of turned components play an important role in determining the form, fit and function of mechanical assembly requiremen ts. The geometric accuracy requirements of turned components are usually specifi ed in terms of roundness, straightness, cylindricity and concentricity. In pract ice, the accuracy specifications achievable are infl...
The Geometric Gravitational Internal Problem
González-Martin, G R
2000-01-01
In a geometric unified theory there is an energy momentum equation, apart from the field equations and equations of motion. The general relativity Einstein equation with cosmological constant follows from this energy momentum equation for empty space. For non empty space we obtain a generalized Einstein equation, relating the Einstein tensor to a geometric stress energy tensor. The matching exterior solution is in agreement with the standard relativity tests. Furthermore, there is a Newtonian limit where we obtain Poisson's equation.
Geometric symmetries in light nuclei
Bijker, Roelof
2016-01-01
The algebraic cluster model is is applied to study cluster states in the nuclei 12C and 16O. The observed level sequences can be understood in terms of the underlying discrete symmetry that characterizes the geometrical configuration of the alpha-particles, i.e. an equilateral triangle for 12C, and a regular tetrahedron for 16O. The structure of rotational bands provides a fingerprint of the underlying geometrical configuration of alpha-particles.
Geometric inequalities methods of proving
Sedrakyan, Hayk
2017-01-01
This unique collection of new and classical problems provides full coverage of geometric inequalities. Many of the 1,000 exercises are presented with detailed author-prepared-solutions, developing creativity and an arsenal of new approaches for solving mathematical problems. This book can serve teachers, high-school students, and mathematical competitors. It may also be used as supplemental reading, providing readers with new and classical methods for proving geometric inequalities. .
Directory of Open Access Journals (Sweden)
Pedram Yaghmouri
2016-11-01
Full Text Available Introduction: It seems that investigating the Parameters related to sperm be useful to assess the impactof age onsemen quality.Factors such asdrug dosage, how to get and duration ofmedication use andevenphysiological conditions(sex andage of the animal alsoaffects onthe outcome. Usingthe wrongdoseor inappropriately duration of treatment, causing adverse effects on the antioxidants. The main goal of this study is Using artificial neural network techniques answer this main question that whether Selenium nanoparticles Such account of spermatozoon, percentage of stimulation, sperm viability percentage are effective on mouse sperm parameters or not ? Research method: in this study , In order to predictthenumber ofspermatozoain mice , Mousesperm viabilityand Stimulationpercentage ofMouse , Some of the important propertiessuch as mouse age and The amount of silicananoparticles presence were used As inputs to the neural network Findings. By calculating theparameters such as Matchingcoefficient, the square root oferror, etc., the accuracy and validity of results was evaluated. ANNmodeloptimizedstructure wascalculatedfor predicting the count of spermatozoon, percentage of stimulation, sperm viability percentage withformat2: 7: 1, 6: 2: 1and2: 7: 1respectively. Conclusion: The results of neural network techniques showed that antioxidant selenium nanoparticles affects the parameters of mouse sperm such as count of spermatozoon, percentage of stimulation, sperm viability percentage .
Anarjan, Navideh; Jafarizadeh-Malmiri, Hoda; Nehdi, Imededdine Arbi; Sbihi, Hassen Mohamed; Al-Resayes, Saud Ibrahim; Tan, Chin Ping
2015-01-01
Nanodispersion systems allow incorporation of lipophilic bioactives, such as astaxanthin (a fat soluble carotenoid) into aqueous systems, which can improve their solubility, bioavailability, and stability, and widen their uses in water-based pharmaceutical and food products. In this study, response surface methodology was used to investigate the influences of homogenization time (0.5-20 minutes) and speed (1,000-9,000 rpm) in the formation of astaxanthin nanodispersions via the solvent-diffusion process. The product was characterized for particle size and astaxanthin concentration using laser diffraction particle size analysis and high performance liquid chromatography, respectively. Relatively high determination coefficients (ranging from 0.896 to 0.969) were obtained for all suggested polynomial regression models. The overall optimal homogenization conditions were determined by multiple response optimization analysis to be 6,000 rpm for 7 minutes. In vitro cellular uptake of astaxanthin from the suggested individual and multiple optimized astaxanthin nanodispersions was also evaluated. The cellular uptake of astaxanthin was found to be considerably increased (by more than five times) as it became incorporated into optimum nanodispersion systems. The lack of a significant difference between predicted and experimental values confirms the suitability of the regression equations connecting the response variables studied to the independent parameters.
Dasgupta, K; Sen, D; Mazumder, S; Basak, C B; Joshi, J B; Banerjee, S
2010-06-01
The process parameters (viz. temperature of synthesis, type of catalyst, concentration of catalyst and type of catalyst-support material) for controlling purity of carbon nanotubes synthesized by catalytic chemical vapour deposition of acetylene have been optimized by analyzing the experimental results using Taguchi method. It has been observed that the catalyst-support material has the maximum (59.4%) and the temperature of synthesis has the minimum effect (2.1%) on purity of the nanotubes. At optimum condition (15% ferrocene supported on carbon black at the synthesis temperature of 700 degrees C) the purity of nanotubes was found out to be 96.2% with yield of 1900%. Thermogravimetry has been used to assess purity of nanotubes. These nantubes have been further characterized by scanning electron microscopy, transmission electron microscopy and Raman Spectroscopy. Small angle neutron scattering has been used to find out their average inner and outer diameter using an appropriate model. The nanotubes are well crystallized but with wide range of diameter varying between 20-150 nm.
Cheboyina, Sreekhar; O'Haver, John; Wyandt, Christy M
2006-01-01
A mathematical model was developed based on the theory of drop formation to predict the size of the pellets formed in the freeze pelletization process. Further the model was validated by studying the effect of various parameters on the pellet size such as viscosity of the pellet forming and column liquids, surface/interfacial tension, density difference between pellet forming and column liquids; size, shape, and material of construction of the needle tips and temperatures maintained in the columns. In this study, pellets were prepared from different matrices including polyethylene glycols and waxes. The column liquids studied were silicone oils and aqueous glycerol solutions. The surface/interfacial tension, density difference between pellet forming and column liquids and needle tip size were found to be the most important factors affecting pellet size. The viscosity of the column liquid was not found to significantly affect the size of the pellets. The size of the pellets was also not affected by the pellet forming liquids of low viscosities. An increase in the initial column temperature slightly decreased the pellet size. The mathematical model developed was found to successfully predict the size of the pellets with an average error of 3.32% for different matrices that were studied.
Ayoub, Mohamed; Ahmed, Naveed; Kalaji, Nader; Charcosset, Catherine; Magdy, Ayoub; Fessi, Hatem; Elaissari, Abdelhamid
2011-04-01
Preparation of biodegradable nanoparticles containing active molecule is now taking much attention of researchers. The aim of the present work is to achieve the nanosize particles for the first time by double emulsion (W1/O/W2,) evaporation method to encapsulate hydrophilic substance using high performance stirring apparatus. A fluorescent stable hydrophilic agent (Stilbene derivative) was used as a model drug to be encapsulated. For this purpose, PCL (polycaprolactone) was chosen as polymer in this study. Several kinds of stabilizers [triton-405, tween 80, poloxamer, PVP (polyvinylpyrrolidone), PEG (poly ethylene glycol) & PVA (poly vinyl alcohol)] were investigated and the results indicate that the PVA (0.5% concentration) leads to the most stable double emulsion with the particle size in nano range. Different parameters affecting the size of particles have been studied such as stirring time (for 1st and 2nd emulsion), stirring speed (for 1st and 2nd emulsion), polymer and stabilizer concentrations etc. After duration of one month, the encapsulation efficiency of obtained particles was estimated using U.V. analysis. Transmission Electron Microscopy (TEM) showed that the prepared particles were spherical in shape. The size and size distribution were found to be submicron and ranging from 150 to 400 nm.
Geometric characterization of polymeric macrofibers
Directory of Open Access Journals (Sweden)
A. R. E. Cáceres
Full Text Available ABSTRACTThe geometric characteristics of synthetic macrofibers are important because they affect the behavior of fiber-reinforced concrete (FRC. Because there is a lack of specific, relevant publications in Brazil, the European standard EN14889-2:2006 was adopted as a reference to perform the characterization. Thus, an experimental plan was developed to assess the adequacy of testing procedures for the qualification of synthetic macrofibers for use in FRC. Two types of macrofibers were evaluated. The length measurement was performed using two methods: the caliper method, which is a manual measurement, and the digital image analysis method using the ImageJ software for image processing. These aforementioned methods were used to determine the diameter together with the density method, which is an indirect method that uses the developed length obtained by one of the previous methods. The statistical analyses revealed that the length results are similar regardless of the method used. However, the macrofibers must be pre-stretched to maximize the accuracy of caliper measurements. The caliper method for diameter determination has the disadvantage of underestimating the macrofiber cross-section because of the pressure applied by the load claws. In contrast, the digital image analysis method obtains the projected diameter in a single plane, which overestimate the diameter because the macrofibers are oriented with the pressure of the scanner cover. Thus, these techniques may result in false projections of the diameters that will depend on the level of torsion in the macrofibers. It was concluded that both the caliper method using previously stretched macrofibers and the digital imaging method can be used to measure length. The density method presented the best results for the diameter determination because these results were not affected by the method chosen to determine the length.
Antenna with Dielectric Having Geometric Patterns
Dudley, Kenneth L. (Inventor); Elliott, Holly A. (Inventor); Cravey, Robin L. (Inventor); Connell, John W. (Inventor); Ghose, Sayata (Inventor); Watson, Kent A. (Inventor); Smith, Jr., Joseph G. (Inventor)
2013-01-01
An antenna includes a ground plane, a dielectric disposed on the ground plane, and an electrically-conductive radiator disposed on the dielectric. The dielectric includes at least one layer of a first dielectric material and a second dielectric material that collectively define a dielectric geometric pattern, which may comprise a fractal geometry. The radiator defines a radiator geometric pattern, and the dielectric geometric pattern is geometrically identical, or substantially geometrically identical, to the radiator geometric pattern.
Valotto, Gabrio; Rampazzo, Giancarlo; Visin, Flavia; Gonella, Francesco; Cattaruzza, Elti; Glisenti, Antonella; Formenton, Gianni; Tieppo, Paulo
2015-12-01
Road dust is a non-exhaust source of atmospheric particulate by re-suspension. It is composed of particles originating from natural sources as well as other non-exhaust source such as tire, brake and asphalt wear. The discrimination between atmospheric particles directly emitted from abrasion process and those related to re-suspension is therefore an open issue, as far as the percentage contribution of non-exhaust emissions is becoming more considerable due also to the recent policy actions and the technological upgrades in the automotive field, focused on the reduction of exhaust emissions. In this paper, road dust collected along the bridge that connects Venice (Italy) to the mainland is characterized with a multi-technique approach in order to determine its composition depending on environmental as well as traffic-related conditions. Six pollutant sources of road dust particles were identified by cluster analysis: brake, railway, tire, asphalt, soil + marine, and mixed combustions. Considering the lack of information on this matrix in this area, this study is intended to provide useful information for future identification of road dust re-suspension source in atmospheric particulate.
Feldmann, M; Zimmermann, A; Hoedemaker, M
2006-07-01
It was the aim of this study to investigate the effect of various factors of the milking technique, milking hygiene and environment on microbial contamination of the milking machine. In 31 dairy herds, the degree of bacterial contamination was examined by taking swabs at four locations (teat cup liner, claw, short and long milk tube) before the milking procedure was started using a standardized protocol (DIN ISO 6887-1:1999). Furthermore, the total germ count was determined in the first milk entering the bulk tank as well as in the bulk tank milk following milking. For each farm, the quality of the milking process and the condition of the milking machine as well as of various environmental factors were recorded. A subjective evaluation of the status of the milking cluster or other parts of the milking machine ("good" or "moderate-poor") gave more information about bacterial contamination than the determination of age and type of material used. A temperature of the rinsing water of teat cleaning before milking or of postmilking teat disinfection did not affect the contamination of the milking machine and the bulk tank milk with environmental bacteria. Furthermore, type of bedding material affected bacterial contamination of milking clusters and bulk tank milk. In conclusion, our results suggest that the microbial contamination of the milking machine is not only influenced by the sanitation pro-
Geometric calibration of ERS satellite SAR images
DEFF Research Database (Denmark)
Mohr, Johan Jacob; Madsen, Søren Nørvang
2001-01-01
Geometric calibration of the European Remote Sensing (ERS) Satellite synthetic aperture radar (SAR) slant range images is important in relation to mapping areas without ground reference points and also in relation to automated processing. The relevant SAR system parameters are discussed...... on a seven-year ERS-1 and a four-year ERS-2 time series, the long term stability is found to be sufficient to allow a single calibration covering the entire mission period. A descending and an ascending orbit tandem pair of the ESA calibration site on Flevoland, suitable for calibration of ERS SAR processors...
Parabolic non-diffracting beams: geometrical approach
Sosa-Sánchez, Citlalli Teresa; Silva-Ortigoza, Gilberto; Alejandro Juárez-Reyes, Salvador; de Jesús Cabrera-Rosas, Omar; Espíndola-Ramos, Ernesto; Julián-Macías, Israel; Ortega-Vidals, Paula
2017-08-01
The aim of this work is to present a geometrical characterization of parabolic non-diffracting beams. To this end, we compute the corresponding angular spectrum of the separable non-diffracting parabolic beams in order to determine the one-parameter family of solutions of the eikonal equation associated with this type of beam. Using this information, we compute the corresponding wavefronts and caustic, and find that qualitatively the caustic corresponds to the maximum of the intensity pattern and the wavefronts are deformations of conical surfaces.
中低比转速离心泵叶轮几何参数优化%Optimal design of middle and low specific speed pump impeller geometric parameters
Institute of Scientific and Technical Information of China (English)
王幼民; 杨国太; 桂诗祥; 杨俊峰
2001-01-01
中低比转速离心泵效率普遍不高，主要因素是泵的圆盘摩擦损失过大，而圆盘摩擦损失又和叶轮直径的五次方成正比，针对这一特点，提出了以减少泵的圆盘摩擦损失为目的方法，即以叶轮直径最小为目标函数，综合考虑叶轮进口直径、叶轮叶片进出口安放角，叶轮叶片数等设计变量，建立相应的数学模型，通过优化计算，获得满足一定扬程和流量的上述参数的最优组合，从而提高中低比转数离心泵的效率，缩短泵的设计周期.%The efficiency of middle and low specific speed pump is low,mostly because of the disk friction of pump impeller. The disk friction loss is proportional to the fifth power of impeller diameter. The paper presents a method that enhances the pump efficiency by reducing the pump disk friction losses. The optimum design model is given by using the objective function of minimizing the size of impeller diameter to determine the variables of the vanes' outlet width, angel and inlet angel, diameter and the number. An optimal parameter group that satisfied the capacity and head was obtained through minimzation. The efficiency of middle and low specific speed pumps is enhanced. The design cycle of the pump is shortened.
Yerlikaya, Emrah; Karageçili, Hasan; Aydin, Ruken Zeynep
2016-04-01
Obesity is a key risk for the development of hyperglycemia, hypertension, hyperlipidemia, insulin resistance and is totally referred to as the metabolic disorders. Diabetes mellitus, a metabolic disorder, is related with hyperglycemia, altered metabolism of lipids, carbohydrates and proteins. The minimum defining characteristic feature to identify diabetes mellitus is chronic and substantiated elevation of circulating glucose concentration. In this study, it is aimed to determine the body composition analyze of obese and (obese+diabetes) patients.We studied the datas taken from three independent groups with the body composition analyzer instrument. The body composition analyzer calculates body parameters, such as body fat ratio, body fat mass, fat free mass, estimated muscle mass, and base metabolic rate on the basis of data obtained by Dual Energy X-ray Absorptiometry using Bioelectrical Impedance Analysis. All patients and healthy subjects applied to Siirt University Medico and their datas were taken. The Statistical Package for Social Sciences version 21 was used for descriptive data analysis. When we compared and analyzed three groups datas, we found statistically significant difference between obese, (obese+diabetes) and control groups values. Anova test and tukey test are used to analyze the difference between groups and to do multiple comparisons. T test is also used to analyze the difference between genders. We observed the statistically significant difference in age and mineral amount peducation level among the illiterate and university graduates; fat mass kg, fat percentage, internal lubrication, body mass index, water percentage, protein mass percentage, mineral percentage p<0.05, significant statistically difference were observed. This difference especially may result of a sedentary lifestyle.
Directory of Open Access Journals (Sweden)
Anarjan N
2015-02-01
variables studied to the independent parameters. Keywords: optimization, lipophilic bioactive nanodispersions, response surface methodology
Institute of Scientific and Technical Information of China (English)
CHEN Dongfeng; DONG Xuanpu; FAN Zitian
2012-01-01
Surface composite layer was fabricated on the AZ91D substrate using the lost foam casting (LFC) process.The pre-coating layer rea.cted with melt substrate and formed the composite layer,and the coating was mainly consist of alloying aluminum powder and low-temperature glass powder (PbO-ZnO-Na2O).The vacuum degree,pouring temperature,mold filling process of melt,and pre-coating thickness played an important role during the formation process of composite layer.The results show that surface morphology of composite layer can be divided into three categories:alloying effect of bad and good ceramic layer,alloying effect of good and bad ceramic layer,composite layer of good quality.The main reason for bad alloying layer is that alloying pre-coating thickness is so thin that it is scoured easily and involved in the melt,in addition,it isdifficult for melt to infiltrate into the alloying coating owing to the surface tension of coating when the vacuum degree is excessively low.Bad ceramic layer is because of somewhat lower pouring temperature and the thicker alloying coating,due to the absorption of heat from the melt,making low temperature glass powder pre-coating layer fuse inadequate.Thus,to get good quality composite layer,the process conditions must be appropriate,the result shows that the optimum process parameters are as follows:at a pouring temperature of 800 ℃,vacuum degree of -0.06 MPa,alloying pre-coating thickness of 0.4 mm,and low glass powder pre-coating layer thickness of 1 mm.
Stabilization of LCD devices via geometric alteration.
Jeon, Il; Yoon, MinSung; Lee, Je-Hoon
2013-02-20
Glass bending in LCD displays is an inherent problem that has challenged many engineers. As a solution to this problem, we propose a methodology that can tackle the root of the phenomenon in terms of linear elastic beam theory. Using this hypothesis, we devised a background theory and a solution. In this paper, we present a glass panel to which geometrical changes, such as furrow, groove, and curb have been applied. These geometrical changes are applied to the nonactive area of the glass panel. To confirm the validity of our approach, we conducted simulation tests as well as hands-on experiments to observe the thermo-mechanical behavior of the device under various conditions. The simulation results using the Ansys simulator show that the proposed technique can reduce the deformation level of panel bending by 40%. In the experiment using a bare cell with polarizer films attached and with performing the high temperature reliability test, the deformation level of panel bending is reduced by half compared to the reference glass panel without any geometric alteration.
Thompson, R.S.; Anderson, K.H.; Bartlein, P.J.
2008-01-01
The method of modern analogs is widely used to obtain estimates of past climatic conditions from paleobiological assemblages, and despite its frequent use, this method involved so-far untested assumptions. We applied four analog approaches to a continental-scale set of bioclimatic and plant-distribution presence/absence data for North America to assess how well this method works under near-optimal modern conditions. For each point on the grid, we calculated the similarity between its vegetation assemblage and those of all other points on the grid (excluding nearby points). The climate of the points with the most similar vegetation was used to estimate the climate at the target grid point. Estimates based the use of the Jaccard similarity coefficient had smaller errors than those based on the use of a new similarity coefficient, although the latter may be more robust because it does not assume that the "fossil" assemblage is complete. The results of these analyses indicate that presence/absence vegetation assemblages provide a valid basis for estimating bioclimates on the continental scale. However, the accuracy of the estimates is strongly tied to the number of species in the target assemblage, and the analog method is necessarily constrained to produce estimates that fall within the range of observed values. We applied the four modern analog approaches and the mutual overlap (or "mutual climatic range") method to estimate bioclimatic conditions represented by the plant macrofossil assemblage from a packrat midden of Last Glacial Maximum age from southern Nevada. In general, the estimation approaches produced similar results in regard to moisture conditions, but there was a greater range of estimates for growing-degree days. Despite its limitations, the modern analog technique can provide paleoclimatic reconstructions that serve as the starting point to the interpretation of past climatic conditions.
Institute of Scientific and Technical Information of China (English)
马龙; 郭彤; 赵健; 徐临燕; 陈津平; 傅星; 胡小唐
2011-01-01
将Carré等步长相移法与白光垂直扫描相结合形成了一种白光等步长相移算法,该方法快速、准确、非接触,垂直分辨力可达亚纳米级.测量系统集成了Mirau显微干涉物镜,并通过高精度压电陶瓷纳米定位器带动物镜进行垂直扫描.分析了Carré法应用于白光干涉信号的相位提取的精度,对不同扫描步距以及不同信噪比情况下的测量进行了计算机仿真,确定了测量参数.结合重心法将相位计算的数据范围直接定位于干涉信号的零级条纹,从而省去了相位解包裹过程.通过对微谐振器和标准台阶的测量说明了该方法的有效性,并使用白光相移干涉、白光垂直扫描和单色光相移干涉对44 nm标准台阶进行了测量,并对测量结果进行了比较.%A white light phase shifting method for interferometry with sub-nanometer resolution based on the combination of Carré phase shifting and white light vertical scanning was proposed, which can conduct the measurement fast, accurately and non-contact. The system was composed of a Mirau driven by a high precision piezoelectric transducer. The phase extraction with Carre phase shifting method on white light interferogram was firstly analyzed and several numerical simulations under various scanning step lengths and signal to noise ratios were followed to determine the parameters of the measurement. Then,the centre of mass gravity method was employed to locate the phase computation directly on the zero-order fringe so that the phase unwrapping was no longer needed. The performance of the new method was illustrated through the measurements of the micro-resonator and a 44 nm standard step height, and the comparison of the results of the 44 nm standard step height measurement by white light phase shifting interferometry, white light vertical scanning and phase shifting interferometry was also made.
NPP VIIRS Early On-Orbit Geometric Performance
Wolfe, Robert E.; Lin, Guoqing; Nishihama, Masahiro; Tewari, Krishna; Montano, Enrique
2012-01-01
The NASA/NOAA Visible Infrared Imager Radiometer Suite (VIIRS) instrument on-board the Suomi National Polar-orbiting Partnership (NPP) satellite was launched in October, 2011. The instrument geometric performance includes sensor spatial response, band-to-band co-registration (BBR), and geolocation accuracy and precision. The geometric performance is an important aspect of sensor data record (SDR) calibration and validation. In this paper we will discuss geometric performance parameter characterization using the first seven-month of VIIRS' earth and lunar data, and compare with the at-launch performance using ground testing data and analysis of numerical modeling results as the first step in on-orbit geometric calibration and validation.
Integrating geometric activity images in ANN classification
De Genst, William; Gautama, Sidharta; Bellens, Rik; Canters, Frank
2005-10-01
In this paper we demonstrate how the interaction between innovative methods in the field of computer vision and methods for multi-spectral image classification can help in extracting detailed land-cover / land-use information from Very High Resolution (VHR) satellite imagery. We introduce the novel concept of "geometric activity images", which we define as images encoding the strength of the relationship between a pixel and surrounding features detected through dedicated computer vision methods. These geometric activity images are used as alternatives to more traditional texture images that better describe the geometry of man-made structures and that can be included as additional information in a non-parametric supervised classification framework. We present a number of findings resulting from the integration of geometric activity images and multi-spectral bands in an artificial neural network classification. The geometric activity images we use result from the use of a ridge detector for straight line detection, calculated for different window sizes and for all multi-spectral bands and band-ratio images in a VHR scene. A selection of the most relevant bands to use for classification is carried out using band selection based on a genetic algorithm. Sensitivity analysis is used to assess the importance of each input variable. An application of the proposed methods to part of a Quickbird image taken over the suburban fringe of the city of Ghent (Belgium) shows that we are able to identify roads with much higher accuracy than when using more traditional multi-spectral image classification techniques.
Directory of Open Access Journals (Sweden)
S. K. Lahiri
2009-05-01
Full Text Available This paper describes a robust hybrid artificial neural network (ANN methodology which can offer a superior performance for the important process engineering problems. The method incorporates a hybrid artificial neural network and differential evolution technique (ANN-DE for the efficient tuning of ANN meta parameters. The algorithm has been applied for the prediction of the hold up of the solid liquid slurry flow. A comparison with selected correlations in the literature showed that the developed ANN correlation noticeably improved the prediction of hold up over a wide range of operating conditions, physical properties, and pipe diameters.
Geometric and numerical foundations of movements
Mansard, Nicolas; Lasserre, Jean-Bernard
2017-01-01
This book aims at gathering roboticists, control theorists, neuroscientists, and mathematicians, in order to promote a multidisciplinary research on movement analysis. It follows the workshop “ Geometric and Numerical Foundations of Movements ” held at LAAS-CNRS in Toulouse in November 2015[1]. Its objective is to lay the foundations for a mutual understanding that is essential for synergetic development in motion research. In particular, the book promotes applications to robotics --and control in general-- of new optimization techniques based on recent results from real algebraic geometry.
Giantsoudi, Drosoula; Adams, Judith; MacDonald, Shannon M; Paganetti, Harald
2017-02-01
In proton therapy of posterior fossa tumors, at least partial inclusion of the brainstem in the target is necessary because of its proximity to the tumor and required margins. Additionally, the preferred beam geometry results in directing the field distal edge toward this critical structure, raising concerns for brainstem toxicity. Some treatment techniques place the beam's distal edge within the brainstem (dose-sparing techniques), and others avoid elevated linear energy transfer (LET) of the proton field by placing the distal edge beyond it (LET-sparing techniques). Hybrid approaches are also being used. We examine the dosimetric efficacy of these techniques, accounting for LET-dependent and dose-dependent variable relative biologic effectiveness (RBE) distributions. Six techniques were applied in ependymoma cases: (a) 3-field dose-sparing; (b) 3-field LET-sparing; (c) 2-field dose-sparing, wide angles; (d) 2-field LET-sparing, wide angles; (e) 2-field LET-sparing, steep angles; and (f) 2-field LET-sparing with feathered distal end. Monte Carlo calculated dose, LET, and RBE-weighted dose distributions were compared. Decreased LET values in the brainstem by LET-sparing techniques were accompanied by higher, not statistically significant, median dose: 53.6 Gy(RBE), 53.4 Gy(RBE), and 54.3 Gy(RBE) for techniques (b), (d), and (e) versus 52.1 Gy(RBE) for technique (a). Accounting for variable RBE distributions, the brainstem volume receiving at least 55 Gy(RBE) increased from 72.5% for technique (a) to 80.3% for (b) (Ptechnique (c) to 77.6% for (d) (Ptechniques compared with the corresponding dose-sparing (P=.03 and .004). Extending the proton range beyond the brainstem to reduce LET results in clinically comparable maximum radiobiologic effective dose to this sensitive structure. However this method significantly increasing the brainstem volume receiving RBE-weighted dose higher than 55 Gy(RBE) with possible consequences based on known dose-volume parameters
Capability of geometric features to classify ships in SAR imagery
Lang, Haitao; Wu, Siwen; Lai, Quan; Ma, Li
2016-10-01
Ship classification in synthetic aperture radar (SAR) imagery has become a new hotspot in remote sensing community for its valuable potential in many maritime applications. Several kinds of ship features, such as geometric features, polarimetric features, and scattering features have been widely applied on ship classification tasks. Compared with polarimetric features and scattering features, which are subject to SAR parameters (e.g., sensor type, incidence angle, polarization, etc.) and environment factors (e.g., sea state, wind, wave, current, etc.), geometric features are relatively independent of SAR and environment factors, and easy to be extracted stably from SAR imagery. In this paper, the capability of geometric features to classify ships in SAR imagery with various resolution has been investigated. Firstly, the relationship between the geometric feature extraction accuracy and the SAR imagery resolution is analyzed. It shows that the minimum bounding rectangle (MBR) of ship can be extracted exactly in terms of absolute precision by the proposed automatic ship-sea segmentation method. Next, six simple but effective geometric features are extracted to build a ship representation for the subsequent classification task. These six geometric features are composed of length (f1), width (f2), area (f3), perimeter (f4), elongatedness (f5) and compactness (f6). Among them, two basic features, length (f1) and width (f2), are directly extracted based on the MBR of ship, the other four are derived from those two basic features. The capability of the utilized geometric features to classify ships are validated on two data set with different image resolutions. The results show that the performance of ship classification solely by geometric features is close to that obtained by the state-of-the-art methods, which obtained by a combination of multiple kinds of features, including scattering features and geometric features after a complex feature selection process.
Directory of Open Access Journals (Sweden)
V. González Fernández
2001-07-01
Full Text Available Este trabajo se inserta en el desarrollo de los proyectos de estructuras cilíndricas presurizadas, evaluando y complementando losrecursos existentes para el proyecto de superficies de revolución sometidas a presión externa y considerando las formulacionesanalíticas que toman en cuenta los comportamientos no lineales, tanto geométrico como físico, importantes cuando se desea verificarel colapso de este tipo de estructuras.Con este trabajo se pretende la aplicación de métodos probabilísticos de análisis de resistencia al caso de estructuras en forma desuperficies de revolución sometidas a presión externa. Para cumplir este objetivo serán determinadas las cargas críticas con laformación de lóbulos circunferenciales según la teoría de Reynolds, tomando en consideración las variaciones de algunos parámetrosgeométricos que influyen en esta carga.Palabras claves: Estructura, estabilidad, falla estructural, imperfección geométrica, superficie a presión.______________________________________________________________________________Abstract:This work is inserted in the development of the projects of cylindrical structure under pressure, evaluating and supplementing theexistent resources for the project of circular cylindrical surface under external pressure. In the same are considered the analyticformulations to take into account the non-linear behaviours, (geometric and physic when is necessary to verify the collapse of thistype of structures.The application of probabilistic methods of resistance analysis to the case of structures with shape of cylindrical shell under externalpressure is sought. To complete this objective the critical loads are determined according to Reynolds’s theory taking intoconsideration the variations of some geometric parameters with influence in this load.Key words: Structures, stability, structural failures, imperfections, cylindrical shell under external pressure.
Gonsalves, Michael Oliver
This dissertation describes an automated technique for ascertaining the values of the geometric calibration parameters of an airborne lidar. A least squares approach is employed that adjusts the point cloud to a single planar surface which could be either a narrow airport runway or a dynamic sea surface. Going beyond the customary three boresight angles, the proposed adjustment can determine up to eleven calibration parameters to a precision that renders a negligible contribution to the point cloud's positional uncertainty. Presently under development is the Coastal Zone Mapping and Imaging Lidar (CZMIL), which, unlike most contemporary systems that use oscillating mirrors to reflect the beam, will use a circular spinning prism to refract the laser in the desired direction. This departure from the traditional scanner presents the potential for internal geometric misalignments not previously experienced. Rather than relying on past calibration practices (like requiring data be acquired over a pitched-roof), a more robust method of calibration is established which does not depend on the presence of any cultural features. To develop this new method of calibration, the laser point positioning equation for this lidar was developed first. The system was then simulated in the MATLAB environment. Using these artificial datasets, the behavior of each geometric parameter iii was systematically manipulated, understood and calibrated, while an optimal flight strategy for the calibration acquisition was simultaneously developed. Finally, the total propagated uncertainty (TPU) of the point cloud was determined using a propagation of variances. Using this TPU module, the strength of the calibration solution was assessed. For example, four flight lines each of 20 seconds in duration contained sufficient information to determine the calibration parameters to such a degree of confidence that their contribution to the final point cloud uncertainty was only 0.012m in the horizontal
Institute of Scientific and Technical Information of China (English)
Kumar Avinash; B Deepika; K S Jayappa
2014-01-01
Influence of structural and lithological controls of various drainage patterns and their stream orientations (for 2nd, 3rd and 4th order steams) were identified to evaluate the direction and controlling factors of drainage network. To investigate the prospect of groundwater, hydrogeomor-phological features of river basin viz. Mulki-Pavanje were identified and mapped. To evaluate the characteristics of the basin, different morphometric parameters (linear, areal and relief) were com-puted in sub-basin wise (SB-I to -VII). The linear parameters suggest drainage network is controlled by geomorphology. The form factor (Ff), elongation ratio (Re) and circularity ratio (Rc) suggest that the basin is in an elongated shape. The drainage density (Dd) indicates resistant/permeable strata un-der medium-dense vegetation with moderate relief. The areal parameters of the sub-basins (except SB-I and III) indicates moderate ground-slopes associated with moderately permeable rocks, which pro-mote moderate run-off and infiltration. Drainage texture (T) of the whole basin indicates coarse tex-ture while the SB-I, and III showing an intermediate texture. The relief parameters namely rugged-ness number (Rn) infers low basin relief and poor drainage density. To identify the most deficit/surplus zones of groundwater suitable weightages were assigned to the hydrogeomorphological units and morphometric parameters. The study reveal that the basin manifest that SB-III shall be most deficit zone of groundwater, whereas SB-VII, VI and V are found to show increase in groundwater potential-ity. Groundwater prospect area in this basin is estimated to be 7% area under poor, 44% area under moderate and 49% area under good to excellent. This paper demonstrated the potential application of geographical information system (GIS) techniques to evaluate the groundwater prospect in absence of traditional groundwater monitoring data.
Geometric registration and rectification of spaceborne SAR imagery
Curlander, J. C.; Pang, S. N.
1982-01-01
This paper describes the development of automated location and geometric rectification techniques for digitally processed synthetic aperture radar (SAR) imagery. A software package has been developed that is capable of determining the absolute location of an image pixel to within 60 m using only the spacecraft ephemeris data and the characteristics of the SAR data collection and processing system. Based on this location capability algorithms have been developed that geometrically rectify the imagery, register it to a common coordinate system and mosaic multiple frames to form extended digital SAR maps. These algorithms have been optimized using parallel processing techniques to minimize the operating time. Test results are given using Seasat SAR data.
Optimal Geometric Partitions, Covers and K-Centers
Andreica, Mugurel Ionut; Andreica, Cristina Teodora; Andreica, Romulus; Ungureanu, Mihai Aristotel
2009-01-01
In this paper we present some new, practical, geometric optimization techniques for computing polygon partitions, 1D and 2D point, interval, square and rectangle covers, as well as 1D and 2D interval and rectangle K-centers. All the techniques we present have immediate applications to several cost optimization and facility location problems which are quite common in practice. The main technique employed is dynamic programming, but we also make use of efficient data structures and fast greedy algorithms.
Geometric procedures for civil engineers
Tonias, Elias C
2016-01-01
This book provides a multitude of geometric constructions usually encountered in civil engineering and surveying practice. A detailed geometric solution is provided to each construction as well as a step-by-step set of programming instructions for incorporation into a computing system. The volume is comprised of 12 chapters and appendices that may be grouped in three major parts: the first is intended for those who love geometry for its own sake and its evolution through the ages, in general, and, more specifically, with the introduction of the computer. The second section addresses geometric features used in the book and provides support procedures used by the constructions presented. The remaining chapters and the appendices contain the various constructions. The volume is ideal for engineering practitioners in civil and construction engineering and allied areas.
Geometric scalar theory of gravity
Energy Technology Data Exchange (ETDEWEB)
Novello, M.; Bittencourt, E.; Goulart, E.; Salim, J.M.; Toniato, J.D. [Instituto de Cosmologia Relatividade Astrofisica ICRA - CBPF Rua Dr. Xavier Sigaud 150 - 22290-180 Rio de Janeiro - Brazil (Brazil); Moschella, U., E-mail: novello@cbpf.br, E-mail: eduhsb@cbpf.br, E-mail: Ugo.Moschella@uninsubria.it, E-mail: egoulart@cbpf.br, E-mail: jsalim@cbpf.br, E-mail: toniato@cbpf.br [Università degli Studi dell' Insubria - Dipartamento di Fisica e Matematica Via Valleggio 11 - 22100 Como - Italy (Italy)
2013-06-01
We present a geometric scalar theory of gravity. Our proposal will be described using the ''background field method'' introduced by Gupta, Feynman, Deser and others as a field theory formulation of general relativity. We analyze previous criticisms against scalar gravity and show how the present proposal avoids these difficulties. This concerns not only the theoretical complaints but also those related to observations. In particular, we show that the widespread belief of the conjecture that the source of scalar gravity must be the trace of the energy-momentum tensor — which is one of the main difficulties to couple gravity with electromagnetic phenomenon in previous models — does not apply to our geometric scalar theory. From the very beginning this is not a special relativistic scalar gravity. The adjective ''geometric'' pinpoints its similarity with general relativity: this is a metric theory of gravity. Some consequences of this new scalar theory are explored.
Udawatta, Ranjith P.; Gantzer, Clark J.; Anderson, Stephen H.; Assouline, Shmuel
2016-05-01
Soil compaction degrades soil structure and affects water, heat, and gas exchange as well as root penetration and crop production. The objective of this study was to use X-ray computed microtomography (CMT) techniques to compare differences in geometrical soil pore parameters as influenced by compaction of two different aggregate size classes. Sieved (diameter Compaction reduced porosity, average pore size, number of pores, and characteristic constants. The average pore radii (63.7 and 61 µm; p < 0.04), largest pore volume (1.58 and 0.58 mm3; p = 0.06), number of pores (55 and 50; p = 0.09), and characteristic coordination number (3.74 and 3.94; p = 0.02) were significantly different between the low-density than the high-density treatment. Aggregate size also influenced measured geometrical pore parameters. This analytical technique provides a tool for assessing changes in soil pores that affect hydraulic properties and thereby provides information to assist in assessment of soil management systems.
Geometric identities in stereological particle analysis
DEFF Research Database (Denmark)
Kötzer, S.; Jensen, Eva Bjørn Vedel; Baddeley, A.
We review recent findings about geometric identities in integral geometry and geometric tomography, and their statistical application to stereological particle analysis. Open questions are discussed.......We review recent findings about geometric identities in integral geometry and geometric tomography, and their statistical application to stereological particle analysis. Open questions are discussed....
Geometric orbit datum and orbit covers
Institute of Scientific and Technical Information of China (English)
梁科; 侯自新
2001-01-01
Vogan conjectured that the parabolic induction of orbit data is independent of the choice of the parabolic subgroup. In this paper we first give the parabolic induction of orbit covers, whose relationship with geometric orbit datum is also induced. Hence we show a geometric interpretation of orbit data and finally prove the conjugation for geometric orbit datum using geometric method.
A Geometric Formulation of Supersymmetry
Freedman, Daniel Z; Van Proeyen, Antoine
2016-01-01
The scalar fields of supersymmetric models are coordinates of a geometric space. We propose a formulation of supersymmetry that is covariant with respect to reparametrizations of this target space. Employing chiral multiplets as an example, we introduce modified supersymmetry variations and redefined auxiliary fields that transform covariantly under reparametrizations. The resulting action and transformation laws are manifestly covariant and highlight the geometric structure of the supersymmetric theory. The covariant methods are developed first for general theories (not necessarily supersymmetric) whose scalar fields are coordinates of a Riemannian target space.
Height and Tilt Geometric Texture
DEFF Research Database (Denmark)
Andersen, Vedrana; Desbrun, Mathieu; Bærentzen, Jakob Andreas
2009-01-01
We propose a new intrinsic representation of geometric texture over triangle meshes. Our approach extends the conventional height field texture representation by incorporating displacements in the tangential plane in the form of a normal tilt. This texture representation offers a good practical...... compromise between functionality and simplicity: it can efficiently handle and process geometric texture too complex to be represented as a height field, without having recourse to full blown mesh editing algorithms. The height-and-tilt representation proposed here is fully intrinsic to the mesh, making...
Geometric integration for particle accelerators
Energy Technology Data Exchange (ETDEWEB)
Forest, Etienne [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)
2006-05-12
This paper is a very personal view of the field of geometric integration in accelerator physics-a field where often work of the highest quality is buried in lost technical notes or even not published; one has only to think of Simon van der Meer Nobel prize work on stochastic cooling-unpublished in any refereed journal. So I reconstructed the relevant history of geometrical integration in accelerator physics as much as I could by talking to collaborators and using my own understanding of the field. The reader should not be too surprised if this account is somewhere between history, science and perhaps even fiction.
Geometric pumping in autophoretic channels
Michelin, Sebastien; De Canio, Gabriele; Lobato-Dauzier, Nicolas; Lauga, Eric
2015-01-01
Many microfluidic devices use macroscopic pressure differentials to overcome viscous friction and generate flows in microchannels. In this work, we investigate how the chemical and geometric properties of the channel walls can drive a net flow by exploiting the autophoretic slip flows induced along active walls by local concentration gradients of a solute species. We show that chemical patterning of the wall is not required to generate and control a net flux within the channel, rather channel geometry alone is sufficient. Using numerical simulations, we determine how geometric characteristics of the wall influence channel flow rate, and confirm our results analytically in the asymptotic limit of lubrication theory.
Asymptotic geometric analysis, part I
Artstein-Avidan, Shiri
2015-01-01
The authors present the theory of asymptotic geometric analysis, a field which lies on the border between geometry and functional analysis. In this field, isometric problems that are typical for geometry in low dimensions are substituted by an "isomorphic" point of view, and an asymptotic approach (as dimension tends to infinity) is introduced. Geometry and analysis meet here in a non-trivial way. Basic examples of geometric inequalities in isomorphic form which are encountered in the book are the "isomorphic isoperimetric inequalities" which led to the discovery of the "concentration phenomen
An introduction to geometrical physics
Aldrovandi, R
1995-01-01
This book stresses the unifying power of the geometrical framework in bringing together concepts from the different areas of physics. Common underpinnings of optics, elasticity, gravitation, relativistic fields, particle mechanics and other subjects are underlined. It attempts to extricate the notion of space currently in the physical literature from the metric connotation.The book's goal is to present mathematical ideas associated with geometrical physics in a rather introductory language. Included are many examples from elementary physics and also, for those wishing to reach a higher level o
Directory of Open Access Journals (Sweden)
Luciano da Silva Cabral
2011-09-01
Full Text Available This study aimed to validate the estimates of the ruminal degradation of total carbohydrates (TC, ruminal and total digestion of fibrous carbohydrates (FC and microbial nitrogen flow in the abomasum evaluated by in vitro gas production technique (IVGP. Six ruminally and abomasally cannulated steers arranged in a double 3 × 3 latin square were used to measure described parameters with indigestible neutral detergent fiber (INDF utilization as marker. Total and fibrous carbohydrates degraded in the rumen were estimated through digestion rates obtained for fibrous (FC and non fibrous carbohydrates (NFC using in vitro gas production technique, corrected for its respective ruminal and postruminal passage rates. The estimation of the total digestion of FC was done by the sum of ruminal and post-ruminal digestion of these compounds. The microbial nitrogen flow in the abomasum was estimated by the calculating the microbial efficiency of bacteria that ferment FC and NFC, utilizing the microbial growth rate obtained by the ruminal digestion rate for carbohydrate fractions in IVGP. The utilization of the in vitro gas production technique allows obtaining accurate estimates of the ruminal digestion of total carbohydrates, total and ruminal digestion of fiber carbohydrates and microbial protein flow in the abomasum.
Ju, Taeho; Achenbach, Jan D.; Jacobs, Laurence J.; Qu, Jianmin
2017-02-01
In this study, we developed a non-collinear mixing technique to measure the Acoustic Nonlinearity Parameter (ANLP) of adhesive bonds. One of the most significant features of the new method is that it requires only one-side access to the adhesive bond being measured, which significantly increases its utility in field measurements. To demonstrate the effectiveness of the newly developed technique, an adhesively jointed aluminum sample was measured with different thermal aging times, using the non-collinear mixing technique with a longitudinal and a shear wave as incident waves to obtain the ANLP of the adhesive bond. The measured results clearly show that the ANLP varies with aging time. To verify that the signals received from the shear wave receiver are indeed the mixing wave, the finite element method was used to simulate the wave motion in the test sample. The simulation results clearly show that the signals recorded by the shear wave receiver are the desired mixing wave, whose amplitude is proportional to the ANLP of the adhesive bond.
Compensation of geometrical deformations for watermark extraction in digital cinema application
Delannay, Damien; Delaigle, Jean-Francois; Macq, Benoit M. M.; Barlaud, Michel
2001-08-01
In this paper, we investigate the restoration of geometrically altered digital images with the aim of recovering an embedded watermark information. More precisely, we focus on the distorsion taking place by the camera acquisition of an image. Indeed, in the cinema industry, a large part of early movie piracy comes from copies made in the theater itself with a camera. The evolution towards digital cinema broadcast enables watermark based fingerprinting protection systems. The first step for fingerprint extraction of a counterfeit material is the compensation of the geometrical deformation inherent to the acquisition process. In order to compensate the deformations, we use a modified 12-parameters bilinear transformation model which closely matches the deformations taking place by an analog acquisition process. The estimation of the parameters can either be global, either vary across regions within the image. Our approach consist in the estimation of the displacement of a number of of pixels via a modified block-matching technique followed by a minimum mean square error optimization of the parameters on basis of those estimated displacement-vectors. The estimated transformation is applied to the candidate image to get a reconstruction as close as possible to the original image. Classical watermark extraction procedure can follow.
Gray, James; He, Yang-Hui; Jejjala, Vishnu; Mekareeya, Noppadol
2008-01-01
We take new algebraic and geometric perspectives on the old subject of SQCD. We count chiral gauge invariant operators using generating functions, or Hilbert series, derived from the plethystic programme and the Molien-Weyl formula. Using the character expansion technique, we also see how the global symmetries are encoded in the generating functions. Equipped with these methods and techniques of algorithmic algebraic geometry, we obtain the character expansions for theories with arbitrary numbers of colours and flavours. Moreover, computational algebraic geometry allows us to systematically study the classical vacuum moduli space of SQCD and investigate such structures as its irreducible components, degree and syzygies. We find the vacuum manifolds of SQCD to be affine Calabi-Yau cones over weighted projective varieties.
Reduction technique for tire contact problems
Noor, Ahmed K.; Peters, Jeanne M.
1995-04-01
A reduction technique and a computational procedure are presented for predicting the tire contact response and evaluating the sensitivity coefficients of the different response quantities. The sensitivity coefficients measure the sensitivity of the contact response to variations in the geometric and material parameters of the tire. The tire is modeled using a two-dimensional laminated anisotropic shell theory with the effects of variation in geometric and material parameters, transverse shear deformation, and geometric nonlinearities included. The contact conditions are incorporated into the formulation by using a perturbed Lagrangian approach with the fundamental unknowns consisting of the stress resultants, the generalized displacements, and the Lagrange multipliers associated with the contact conditions. The elemental arrays are obtained by using a modified two-field, mixed variational principle. For the application of the reduction technique, the tire finite element model is partitioned into two regions. The first region consists of the nodes that are likely to come in contact with the pavement, and the second region includes all the remaining nodes. The reduction technique is used to significantly reduce the degrees of freedom in the second region. The effectiveness of the computational procedure is demonstrated by a numerical example of the frictionless contact response of the space shuttle nose-gear tire, inflated and pressed against a rigid flat surface.
Reig-Ferrer, Abilio; Ferrer-Cascales, Rosario; Santos-Ruiz, Ana; Campos-Ferrer, Adolfo; Prieto-Seva, Alvaro; Velasco-Ruiz, Irene; Fernandez-Pascual, Maria Dolores; Albaladejo-Blazquez, Natalia
2014-08-23
The aging process involves a decline in immune functioning that renders elderly people more vulnerable to disease. In residential programs for the aged, it is vital to diminish their risk of disease, promote their independence, and augment their psychological well-being and quality of life. We performed a randomized controlled study, evaluating the ability of a relaxation technique based on Benson's relaxation response to enhance psychological well-being and modulate the immune parameters of elderly people living in a geriatric residence when compared to a waitlist control group. The study included a 2-week intervention period and a 3-month follow-up period. The main outcome variables were psychological well-being and quality of life, biomedical variables, immune changes from the pre-treatment to post-treatment and follow-up periods. Our findings reveal significant differences between the experimental and control groups in CD19, CD71, CD97, CD134, and CD137 lymphocyte subpopulations at the end of treatment. Furthermore, there was a decrease in negative affect, psychological discomfort, and symptom perception in the treatment group, which increased participants' quality of life scores at the three-month follow-up. This study represents a first approach to the application of a passive relaxation technique in residential programs for the elderly. The method appears to be effective in enhancing psychological well-being and modulating immune activity in a group of elderly people. This relaxation technique could be considered an option for achieving health benefits with a low cost for residential programs, but further studies using this technique in larger samples of older people are needed to confirm the trends observed in the present study. International Standard Randomised Controlled Trial Number Register ISRCTN85410212.
In Defence of Geometrical Algebra
Blasjo, V.N.E.
2016-01-01
The geometrical algebra hypothesis was once the received interpretation of Greek mathematics. In recent decades, however, it has become anathema to many. I give a critical review of all arguments against it and offer a consistent rebuttal case against the modern consensus. Consequently, I find that
Metastable vacua and geometric deformations
Amariti, A; Girardello, L; Mariotti, A
2008-01-01
We study the geometric interpretation of metastable vacua for systems of D3 branes at non isolated toric deformable singularities. Using the L^{aba} examples, we investigate the relations between the field theoretic susy breaking and restoration and the complex deformations of the CY singularities.
Geometrical product specifications heat-resistant cobalt cast alloy
Directory of Open Access Journals (Sweden)
Lyubimov V.
2007-01-01
Full Text Available Geometrical product specification MAR-M509 cast cobalt alloy depend beginning temperature of multilayer ceramic shell moulds (MCS. It has found that go down temperature of MCS from 1000°C to 200°C, the increase surface roughness and its amplitude parameters: Sa, Sz, St, Sq, Sp and Sv.
Geometrically invariant color image watermarking scheme using feature points
Institute of Scientific and Technical Information of China (English)
WANG XiangYang; MENG Lan; YANG HongYing
2009-01-01
Geometric distortion is known as one of the most difficult attacks to resist.Geometric distortion desynchronizes the location of the watermark and hence causes incorrect watermark detection.In this paper,we propose a geometrically invariant digital watermarking method for color images.In order to synchronize the location for watermark insertion and detection,we use a multi-scale Harris-Laplace detector,by which feature points of a color image can be extracted that are invariant to geometric distortions.Then,the self-adaptive local image region (LIR) detection based on the feature scale theory was considered for watermarking.At each local image region,the watermark is embedded after image normalization.By binding digital watermark with invariant image regions,resilience against geometric distortion can be readily obtained.Our method belongs to the category of blind watermarking techniques,because we do not need the original image during detection.Experimental results show that the proposed color image watermarking is not only invisible and robust against common signal processing such as sharpening,noise adding,and JPEG compression,but also robust against the geometric distortions such as rotation,translation,scaling,row or column removal,shearing,and local random bend.
Geometric hashing and object recognition
Stiller, Peter F.; Huber, Birkett
1999-09-01
We discuss a new geometric hashing method for searching large databases of 2D images (or 3D objects) to match a query built from geometric information presented by a single 3D object (or single 2D image). The goal is to rapidly determine a small subset of the images that potentially contain a view of the given object (or a small set of objects that potentially match the item in the image). Since this must be accomplished independent of the pose of the object, the objects and images, which are characterized by configurations of geometric features such as points, lines and/or conics, must be treated using a viewpoint invariant formulation. We are therefore forced to characterize these configurations in terms of their 3D and 2D geometric invariants. The crucial relationship between the 3D geometry and its 'residual' in 2D is expressible as a correspondence (in the sense of algebraic geometry). Computing a set of generating equations for the ideal of this correspondence gives a complete characterization of the view of independent relationships between an object and all of its possible images. Once a set of generators is in hand, it can be used to devise efficient recognition algorithms and to give an efficient geometric hashing scheme. This requires exploiting the form and symmetry of the equations. The result is a multidimensional access scheme whose efficiency we examine. Several potential directions for improving this scheme are also discussed. Finally, in a brief appendix, we discuss an alternative approach to invariants for generalized perspective that replaces the standard invariants by a subvariety of a Grassmannian. The advantage of this is that one can circumvent many annoying general position assumptions and arrive at invariant equations (in the Plucker coordinates) that are more numerically robust in applications.
Directory of Open Access Journals (Sweden)
H. Vanhamäki
2011-03-01
Full Text Available We present a review of selected data-analysis methods that are frequently applied in studies of ionospheric electrodynamics and magnetosphere-ionosphere coupling using ground-based and space-based data sets. Our focus is on methods that are data driven (not simulations or statistical models and can be used in mesoscale studies, where the analysis area is typically some hundreds or thousands of km across. The selection of reviewed methods is such that most combinations of measured input data (electric field, conductances, magnetic field and currents that occur in practical applications are covered. The techniques are used to solve the unmeasured parameters from Ohm's law and Maxwell's equations, possibly with help of some simplifying assumptions. In addition to reviewing existing data-analysis methods, we also briefly discuss possible extensions that may be used for upcoming data sets.
Saha, Sajib; Lambert, Andrew; Pickering, Mark
2015-01-01
In this paper, we systematically evaluate the performance of adaptive adjustment of the relaxation parameters of various iterative algorithms for X-ray CT reconstruction relying on sparsity priors. Sparsity prior has been found to be an efficient strategy in CT reconstruction where significantly fewer attenuation measurements are available. Sparsity prior CT reconstruction relies on iterative algorithms such as the algebraic reconstruction technique (ART) to produce a crude reconstruction based on which a sparse approximation is performed. Data driven adjustment of relaxation has been found to ensure better convergence than traditional relaxation for ART. In this paper, we study the performance of such data driven relaxation on a (CS) compressed sensing environment. State-of-the-art algorithms are implemented and their performance analyzed in regard to conventional and data-driven relaxation. Experiments are performed both on simulated and real environments. For the simulated case, experiments are conducted w...
Geometric Algorithms for Private-Cache Chip Multiprocessors
DEFF Research Database (Denmark)
Ajwani, Deepak; Sitchinava, Nodari; Zeh, Norbert
2010-01-01
We study techniques for obtaining efficient algorithms for geometric problems on private-cache chip multiprocessors. We show how to obtain optimal algorithms for interval stabbing counting, 1-D range counting, weighted 2-D dominance counting, and for computing 3-D maxima, 2-D lower envelopes, and 2...
Geometrical metrology on silicone rubber by computed tomography
DEFF Research Database (Denmark)
Müller, Pavel; Pacurar, Ramona Alexandra; De Chiffre, Leonardo
2011-01-01
Computed tomography (CT) represents a suitable measuring technique for investigation of deformable materials, since no forces are developed on the part during scanning. As for any other measuring instruments, the traceability of the CT scanners needs to be assured. An investigation on geometrical...
Directory of Open Access Journals (Sweden)
Daniela Nickel
2016-01-01
Full Text Available Anodisation is essential for improving surface properties of aluminium alloys and composites regarding wear and corrosion behaviour. Optimisation of the anodising process depends on microstructural constituents contained in aluminium alloys and represents a key task, consisting of the control of process parameters and electrolyte formulation. We applied the micro-capillary technique known from corrosion studies and modified it to form anodic aluminium oxide films on high-strength aluminium alloys in comparison to pure aluminium in sulphuric acid. A glass capillary with an opening of 800 μm in diameter was utilized. Corresponding electrochemical measurements during potentiodynamic and potentiostatic anodisation revealed anodic current responses similar to conventional anodisation. The measurement of film thickness was adapted to the thin anodised spots using ellipsometry and energy dispersive X-ray analysis. Cross sections prepared by focused ion beam milling confirm the thickness results and show the behaviour of intermetallic phases depending on the anodising potential. Consequently, micro-capillary anodising proved to be an effective tool for developing appropriate anodisation conditions for aluminium alloys and composites because it allows quick variation of electrolyte composition by applying low electrolyte volumes and rapid film formation due to short process durations at small areas and more flexible variation of process parameters due to the used set-up.
Ghosh, Indrajit; Schenck, Daniel; Bose, Sonali; Ruegger, Colleen
2012-11-20
The purpose of this study was to develop nanosuspension formulations of a poorly soluble drug using a wet media milling technique. The milling process was optimized by studying the effects of critical process parameters on the size of nanoparticles using a factorial design approach. During the design of experiments (DOEs) study, different concentrations of Vitamin E TPGS in the suspensions were used to evaluate its influence on the stabilization of a nanosuspension. Once the final formulation was optimized, a pharmacokinetic study was performed in beagle dogs to investigate the effect of different ranges of particle size of nanocrystals on the plasma profile. A significant increase in AUC and C(max) was observed when the drug substance was converted into nanocrystals, likely due to the increase in dissolution rate. Results also revealed that the nanosuspension formulation (consists of nanocrystals with narrow size distribution, having a mean particle size<300 nm) produced less variability with regards to the individual plasma concentrations in the dogs when compared an alternate nanocrystal formulation (consists of nanocrystals with broad size distribution having a mean particle size<750 nm). This type of observation can be explained due to the Ostwald ripening phenomena between the nanocrystals when the particle size distribution was very broad (higher poly dispersity index). Surprisingly, the un-micronized suspension containing Vitamin E TPGS did not show any significant impact on pharmacokinetic parameters.
Optimization of biotechnological systems through geometric programming
Directory of Open Access Journals (Sweden)
Torres Nestor V
2007-09-01
Full Text Available Abstract Background In the past, tasks of model based yield optimization in metabolic engineering were either approached with stoichiometric models or with structured nonlinear models such as S-systems or linear-logarithmic representations. These models stand out among most others, because they allow the optimization task to be converted into a linear program, for which efficient solution methods are widely available. For pathway models not in one of these formats, an Indirect Optimization Method (IOM was developed where the original model is sequentially represented as an S-system model, optimized in this format with linear programming methods, reinterpreted in the initial model form, and further optimized as necessary. Results A new method is proposed for this task. We show here that the model format of a Generalized Mass Action (GMA system may be optimized very efficiently with techniques of geometric programming. We briefly review the basics of GMA systems and of geometric programming, demonstrate how the latter may be applied to the former, and illustrate the combined method with a didactic problem and two examples based on models of real systems. The first is a relatively small yet representative model of the anaerobic fermentation pathway in S. cerevisiae, while the second describes the dynamics of the tryptophan operon in E. coli. Both models have previously been used for benchmarking purposes, thus facilitating comparisons with the proposed new method. In these comparisons, the geometric programming method was found to be equal or better than the earlier methods in terms of successful identification of optima and efficiency. Conclusion GMA systems are of importance, because they contain stoichiometric, mass action and S-systems as special cases, along with many other models. Furthermore, it was previously shown that algebraic equivalence transformations of variables are sufficient to convert virtually any types of dynamical models into
Shen, Jesse; Kadoury, Samuel; Labelle, Hubert; Parent, Stefan
2016-12-15
Consecutive case series analysis. To evaluate the surgical outcomes of patients with thoracic adolescent idiopathic scoliosis (AIS) in relation to different degrees of geometric torsion. AIS is a three-dimensional (3D) deformity of the spine. A 3D classification of AIS, however, remains elusive because there is no widely accepted 3D parameter in the clinical practice. Recently, a new method of estimating geometric torsion has been proposed and detected two potential new 3D subgroups based on geometric torsion values. This is an analysis of 93 patients with Lenke type-1 deformity from our institution. 3D reconstructions were obtained using biplanar radiographs both pre- and postoperatively. Geometric torsion was computed using a novel technique by approximating local arc lengths at the neutral vertebra in the thoracolumbar segment. An inter- and intragroup statistical analysis was performed to compare clinical indices of patients with different torsion values. A qualitative assessment was also performed on each patient by two senior staff surgeons. Statistically significant differences were observed in clinical indices between high (2.85 mm) and low torsion (0.83 mm) Lenke type 1 subgroups. Preoperatively, the high torsion group showed higher Cobb angle values in the thoracic segment (71.18° vs. 63.74°), as well as higher angulation in the thoracolumbar plane of maximum deformity (67.79° vs. 53.30°). Postoperatively, a statistically significant difference was found in the orientation of the plane of maximum deformity in the thoracolumbar segment between the high and low torsion groups (47.95° vs. 30.03°). Results from the qualitative evaluation of surgical results showed different results between the two staff surgeons. These results suggest a link between preoperative torsion values and surgical outcomes within Lenke type 1 deformities. These results will need to be validated by an independent group, as it is a single-center study. 4.
Geometric modeling and analysis of large latticed surfaces
Nayfeh, A. H.; Hefzy, M. S.
1980-01-01
The application of geometrical schemes, similar to geodesic domes, to large spherical antenna reflectors was investigated. The shape and size of flat segmented latticed surfaces which approximate general shells of revolution, and in particular spherical and paraboloidal reflective surfaces, were determined. The extensive mathematical and computational geometric analyses of the reflector resulted in the development of a general purpose computer program capable of generating the complete design parameters of the dish. The program also includes a graphical self contained subroutine for graphic display of the required design.
Hadronic and elementary multiplicity distributions in a geometrical approach
Valin, P; Menon, M J
2000-01-01
We construct the hadronic multiplicity distribution in terms of an elementary distribution (at given impact parameter) and the inelastic overlap function characterized by the observed BEL (Blacker-Edgier-Larger) behaviour. With suitable parametrizations for the elementary quantities, based on some geometrical arguments and the most recent data on e+e- annihilation, an excellent description of pp and p(bar)p inelastic multiplicity distributions at the highest energies is obtained. With this approach, we quantitatively correlate the violations of scalings in multiplicity distributions (Koba-Nielsen-Olesen) and elastic scattering (Geometrical) at high energies.
Guiding light via geometric phases
Slussarenko, Sergei; Jisha, Chandroth P; Piccirillo, Bruno; Santamato, Enrico; Assanto, Gaetano; Marrucci, Lorenzo
2015-01-01
Known methods for transverse confinement and guidance of light can be grouped into a few basic mechanisms, the most common being metallic reflection, total internal reflection and photonic-bandgap (or Bragg) reflection. All of them essentially rely on changes of the refractive index, that is on scalar properties of light. Recently, processes based on "geometric Berry phases", such as manipulation of polarization states or deflection of spinning-light rays, have attracted considerable interest in the contexts of singular optics and structured light. Here, we disclose a new approach to light waveguiding, using geometric Berry phases and exploiting polarization states and their handling. This can be realized in structured three-dimensional anisotropic media, in which the optic axis lies orthogonal to the propagation direction and is modulated along it and across the transverse plane, so that the refractive index remains constant but a phase distortion can be imposed on a beam. In addition to a complete theoretic...
A Geometrical Method of Decoupling
Baumgarten, Christian
2012-01-01
In a preceeding paper the real Dirac matrices have been introduced to coupled linear optics and a recipe to decouple positive definite Hamiltonians has been given. In this article a geometrical method is presented which allows to decouple regular {\\it and} irregular systems with the same straightforward method and to compute the eigenvalues and eigenvectors of Hamiltonian matrices with both, real and imaginary eigenvalues. It is shown that the algebraic decoupling is closely related to a geometric "decoupling" by the orthogonalization of the vectors $\\vec E$, $\\vec B$ and $\\vec p$, that were introduced with the so-called "electromechanical equivalence" (EMEQ). When used iteratively, the decoupling algorithm can also be applied to n-dimensional non-dissipative systems.
Energy Technology Data Exchange (ETDEWEB)
Ostrowsky, A.; Daures, J
2008-07-01
Calorimetry is the most direct dosimetric technique to reach absorbed dose. A calorimeter gives direct access to the energy imparted to matter by ionizing radiation per mass unit by measuring the heat quantity Q produced under irradiation in its sensitive element which is thermally insulated. Graphite was chosen as construction material because all the energy imparted to graphite by ionizing radiation is converted into heat. Thermistors are used for temperature measurements as well as for the electrical heating of the different bodies of the calorimeter. The construction of a calorimeter is the result of a compromise between dosimetric requirements and mechanical constraints. The difficulties encountered are examined and the solutions chosen are detailed. All technical data are gathered in this document. The aim is to provide a practical operative instruction and guidance document, which can help interested laboratories in designing such an instrument. The electrical and thermal tests have shown a good behaviour of the GR9 calorimeter.
Geometrical Aspects of Venus Transit
Bertuola, Alberto C; Magalhães, N S; Filho, Victo S
2016-01-01
We obtained two astronomical values, the Earth-Venus distance and Venus diameter, by means of a geometrical treatment of photos taken of Venus transit in June of 2012. Here we presented the static and translational modelsthat were elaborated taking into account the Earth and Venus orbital movements. An additional correction was also added by considering the Earth rotation movement. The results obtained were compared with the values of reference from literature, showing very good concordance.
Geometric Hyperplanes: Desargues Encodes Doily
Saniga, Metod
2011-01-01
It is shown that the structure of the generalized quadrangle of order two is fully encoded in the properties of the Desargues configuration. A point of the quadrangle is represented by a geometric hyperplane of the Desargues configuration and its line by a set of three hyperplanes such that one of them is the complement of the symmetric difference of the remaining two and they all share a pair of non-collinear points.
Geometrical interpretation of optical absorption
Energy Technology Data Exchange (ETDEWEB)
Monzon, J. J.; Barriuso, A. G.; Sanchez-Soto, L. L. [Departamento de Optica, Facultad de Fisica, Universidad Complutense, E-28040 Madrid (Spain); Montesinos-Amilibia, J. M. [Departamento de Geometria y Topologia, Facultad de Matematicas, Universidad Complutense, E-28040 Madrid (Spain)
2011-08-15
We reinterpret the transfer matrix for an absorbing system in very simple geometrical terms. In appropriate variables, the system appears as performing a Lorentz transformation in a (1 + 3)-dimensional space. Using homogeneous coordinates, we map that action on the unit sphere, which is at the realm of the Klein model of hyperbolic geometry. The effects of absorption appear then as a loxodromic transformation, that is, a rhumb line crossing all the meridians at the same angle.
Polar metals by geometric design
Kim, T. H.; Puggioni, D.; Yuan, Y.; Xie, L.; Zhou, H.; Campbell, N.; Ryan, P. J.; Choi, Y.; Kim, J.-W.; Patzner, J. R.; Ryu, S.; Podkaminer, J. P.; Irwin, J.; Ma, Y.; Fennie, C. J.; Rzchowski, M. S.; Pan, X. Q.; Gopalan, V.; Rondinelli, J. M.; Eom, C. B.
2016-05-01
Gauss’s law dictates that the net electric field inside a conductor in electrostatic equilibrium is zero by effective charge screening; free carriers within a metal eliminate internal dipoles that may arise owing to asymmetric charge distributions. Quantum physics supports this view, demonstrating that delocalized electrons make a static macroscopic polarization, an ill-defined quantity in metals—it is exceedingly unusual to find a polar metal that exhibits long-range ordered dipoles owing to cooperative atomic displacements aligned from dipolar interactions as in insulating phases. Here we describe the quantum mechanical design and experimental realization of room-temperature polar metals in thin-film ANiO3 perovskite nickelates using a strategy based on atomic-scale control of inversion-preserving (centric) displacements. We predict with ab initio calculations that cooperative polar A cation displacements are geometrically stabilized with a non-equilibrium amplitude and tilt pattern of the corner-connected NiO6 octahedra—the structural signatures of perovskites—owing to geometric constraints imposed by the underlying substrate. Heteroepitaxial thin-films grown on LaAlO3 (111) substrates fulfil the design principles. We achieve both a conducting polar monoclinic oxide that is inaccessible in compositionally identical films grown on (001) substrates, and observe a hidden, previously unreported, non-equilibrium structure in thin-film geometries. We expect that the geometric stabilization approach will provide novel avenues for realizing new multifunctional materials with unusual coexisting properties.
Geometrical rectification of spin-scan images from Pioneer 11
Strickland, R. N.; Burke, J. J.
1980-01-01
Images of Saturn received from Pioneer 11 suffer from geometrical distortions due to the curvilinear scan lines and the unequal sampling intervals in orthogonal directions, which are inherent in spin-scan imaging. In this paper geometrical image rectification by polynomial transformation based on control points is discussed. Factors that affect the accuracy of reconstruction are shown to include the spatial distribution and spatial density of control points, and the order of the polynomial distortion model. A computer implementation of the technique is described.
A Geometrical Transformations Resistant Digital Watermarking Based on Quantization
Institute of Scientific and Technical Information of China (English)
SHI Lei; HONG Fan; LIU Wei-qun; HU Yu-ping; CHEN Zhuo
2005-01-01
A geometrical transformations resistant digital image watermarking based on quantization is described. Taking advantage of the rotation, scale and translation invariants of discrete Fourier transform(DFT), each watermark bit is embedded into each homocentric circles around the zero frequency term in DFT domain by quantizing the magnitude vector of Fourier spectrum. The embedded sequence can be extracted by "majority principles" without restoring to the original unmarked image. The experimental results show that the watermark is invisible and robust to any combination of geometrical transformations or common image processing techniques.
Optimal control of underactuated mechanical systems: A geometric approach
Colombo, Leonardo; Martín De Diego, David; Zuccalli, Marcela
2010-08-01
In this paper, we consider a geometric formalism for optimal control of underactuated mechanical systems. Our techniques are an adaptation of the classical Skinner and Rusk approach for the case of Lagrangian dynamics with higher-order constraints. We study a regular case where it is possible to establish a symplectic framework and, as a consequence, to obtain a unique vector field determining the dynamics of the optimal control problem. These developments will allow us to develop a new class of geometric integrators based on discrete variational calculus.
Optimal Control of Underactuated Mechanical Systems: A Geometric Approach
Colombo, L; Zuccalli, M
2009-01-01
In this paper, we consider a geometric formalism for optimal control of underactuated mechanical systems. Our techniques are an adaptation of the classical Skinner and Rusk approach for the case of Lagrangian dynamics with higher-order constraints. We study a regular case where it is possible to establish a symplectic framework and, as a consequence, to obtain a unique vector field determining the dynamics of the optimal control problem. These developments will allow us to develop a new class of geometric integrators based on discrete variational calculus.