This document presents a fan-beam reconstruction algorithm for 2D dynamic CT that compensates for time-dependent rotational, uniform scaling, and translational deformations of the object during data acquisition. The algorithm eliminates the computationally expensive position-dependent backprojection weight used in existing algorithms. It first formulates admissibility conditions for deformations that allow exact reconstruction from acquired projections. It then derives a reconstruction formula incorporating a 2D time-dependent deformation model into the fan-beam filtered backprojection (FBP) algorithm without backprojection weight. Finally, it evaluates the proposed algorithm using simulated motion-corrupted projection data.
OPTIMAL BEAM STEERING ANGLES OF A SENSOR ARRAY FOR A MULTIPLE SOURCE SCENARIOcsandit
The document presents methods to optimize beam steering angles of a sensor array to minimize the Cramér-Rao bound (CRB) for angle of arrival (AOA) estimation in multiple source scenarios. Specifically, it derives the gradient and Hessian of the trace of the CRB formula with respect to the beam steering angles. These can be used in a Newton-Raphson iteration to find the optimal beam steering angles that minimize the CRB, and thus provide the best AOA estimation performance according to CRB theory. Simulation results show lower mean squared error when using the optimized beam steering angles compared to usual discrete Fourier transform steering.
GPR Probing of Smoothly Layered Subsurface Medium: 3D Analytical ModelLeonid Krinitsky
An analytical approach to GPR probing of a
horizontally layered subsurface medium is developed, based on the coupled-wave WKB approximation. An empirical model of current in dipole transmitter antenna is used.
Modeling and simulation of ducted axial fan for one dimensional flowiaemedu
The document summarizes research on modeling and simulating a ducted axial fan for one-dimensional flow. It presents the governing continuity, momentum, and energy equations. It then derives the radial equilibrium concept for axial flow, showing that pressure change is proportional to the square of whirl velocity over radius. The paper describes a ducted axial fan test rig and instrumentation. It aims to compute pressure rise by varying parameters like inlet velocity, whirl velocity, rotor speed, and blade diameter using Simulink.
Modeling and simulation of ducted axial fan for one dimensional flow no restr...iaemedu
This document describes modeling and simulation of a ducted axial fan for one-dimensional flow. It presents the governing continuity, momentum and energy equations. It derives the flow model using radial equilibrium concepts to compute pressure rise as a function of whirl velocity, rotor speed and blade diameter. A Simulink model is developed using typical blocks to simulate the one-dimensional flow model. Results show that maximum pressure rise occurs at higher rotor speeds, pressure ratios and larger blade diameters. Flow modeling and simulation helps optimize pressure rise for different operating parameters of the ducted axial fan.
Using Subspace Pursuit Algorithm to Improve Performance of the Distributed Co...Polytechnique Montreal
This paper applies a compressed algorithm to improve the spectrum sensing performance of cognitive radio technology.
At the fusion center, the recovery error in the analog to information converter (AIC) when reconstructing the
transmit signal from the received time-discrete signal causes degradation of the detection performance. Therefore, we
propose a subspace pursuit (SP) algorithm to reduce the recovery error and thereby enhance the detection performance.
In this study, we employ a wide-band, low SNR, distributed compressed sensing regime to analyze and evaluate the
proposed approach. Simulations are provided to demonstrate the performance of the proposed algorithm.
Four experiments were conducted using a paint can hanging from a spring. In the first experiment, the paint can oscillated purely vertically, and PCA isolated this behavior in a single principal component, capturing 95% of the variance. When noise was added by shaking the cameras in the second experiment, PCA was still able to isolate the oscillatory behavior but with less accuracy. In experiments three and four where the paint can moved in both vertical and horizontal directions, PCA extracted the multidimensional behavior with the expected rank and reasonable accuracy.
Object tracking using motion flow projection for pan-tilt configurationIJECEIAES
We propose a new object tracking model for two degrees of freedom mechanism. Our model uses a reverse projection from a camera plane to a world plane. Here, the model takes advantage of optic flow technique by re-projecting the flow vectors from the image space into world space. A pan-tilt (PT) mounting system is used to verify the performance of our model and maintain the tracked object within a region of interest (ROI). This system contains two servo motors to enable a webcam rotating along PT axes. The PT rotation angles are estimated based on a rigid transformation of the the optic flow vectors in which an idealized translation matrix followed by two rotational matrices around PT axes are used. Our model was tested and evaluated using different objects with different motions. The results reveal that our model can keep the target object within a certain region in the camera view.
The document discusses higher dimensional reconstruction techniques for medical imaging. It begins with a review of 3D reconstruction and the mathematical modeling using the Radon transform. It then describes 4D, 5D and 6D reconstruction which add additional dimensions of time, cardiac phase and respiration to the 3D spatial reconstruction. Higher dimensional reconstruction allows for dynamic imaging but introduces additional challenges from increased noise, bias and variance. The document explores techniques like iterative reconstruction to address these issues and improve accuracy. Real patient data is used to demonstrate the reconstruction methods.
OPTIMAL BEAM STEERING ANGLES OF A SENSOR ARRAY FOR A MULTIPLE SOURCE SCENARIOcsandit
The document presents methods to optimize beam steering angles of a sensor array to minimize the Cramér-Rao bound (CRB) for angle of arrival (AOA) estimation in multiple source scenarios. Specifically, it derives the gradient and Hessian of the trace of the CRB formula with respect to the beam steering angles. These can be used in a Newton-Raphson iteration to find the optimal beam steering angles that minimize the CRB, and thus provide the best AOA estimation performance according to CRB theory. Simulation results show lower mean squared error when using the optimized beam steering angles compared to usual discrete Fourier transform steering.
GPR Probing of Smoothly Layered Subsurface Medium: 3D Analytical ModelLeonid Krinitsky
An analytical approach to GPR probing of a
horizontally layered subsurface medium is developed, based on the coupled-wave WKB approximation. An empirical model of current in dipole transmitter antenna is used.
Modeling and simulation of ducted axial fan for one dimensional flowiaemedu
The document summarizes research on modeling and simulating a ducted axial fan for one-dimensional flow. It presents the governing continuity, momentum, and energy equations. It then derives the radial equilibrium concept for axial flow, showing that pressure change is proportional to the square of whirl velocity over radius. The paper describes a ducted axial fan test rig and instrumentation. It aims to compute pressure rise by varying parameters like inlet velocity, whirl velocity, rotor speed, and blade diameter using Simulink.
Modeling and simulation of ducted axial fan for one dimensional flow no restr...iaemedu
This document describes modeling and simulation of a ducted axial fan for one-dimensional flow. It presents the governing continuity, momentum and energy equations. It derives the flow model using radial equilibrium concepts to compute pressure rise as a function of whirl velocity, rotor speed and blade diameter. A Simulink model is developed using typical blocks to simulate the one-dimensional flow model. Results show that maximum pressure rise occurs at higher rotor speeds, pressure ratios and larger blade diameters. Flow modeling and simulation helps optimize pressure rise for different operating parameters of the ducted axial fan.
Using Subspace Pursuit Algorithm to Improve Performance of the Distributed Co...Polytechnique Montreal
This paper applies a compressed algorithm to improve the spectrum sensing performance of cognitive radio technology.
At the fusion center, the recovery error in the analog to information converter (AIC) when reconstructing the
transmit signal from the received time-discrete signal causes degradation of the detection performance. Therefore, we
propose a subspace pursuit (SP) algorithm to reduce the recovery error and thereby enhance the detection performance.
In this study, we employ a wide-band, low SNR, distributed compressed sensing regime to analyze and evaluate the
proposed approach. Simulations are provided to demonstrate the performance of the proposed algorithm.
Four experiments were conducted using a paint can hanging from a spring. In the first experiment, the paint can oscillated purely vertically, and PCA isolated this behavior in a single principal component, capturing 95% of the variance. When noise was added by shaking the cameras in the second experiment, PCA was still able to isolate the oscillatory behavior but with less accuracy. In experiments three and four where the paint can moved in both vertical and horizontal directions, PCA extracted the multidimensional behavior with the expected rank and reasonable accuracy.
Object tracking using motion flow projection for pan-tilt configurationIJECEIAES
We propose a new object tracking model for two degrees of freedom mechanism. Our model uses a reverse projection from a camera plane to a world plane. Here, the model takes advantage of optic flow technique by re-projecting the flow vectors from the image space into world space. A pan-tilt (PT) mounting system is used to verify the performance of our model and maintain the tracked object within a region of interest (ROI). This system contains two servo motors to enable a webcam rotating along PT axes. The PT rotation angles are estimated based on a rigid transformation of the the optic flow vectors in which an idealized translation matrix followed by two rotational matrices around PT axes are used. Our model was tested and evaluated using different objects with different motions. The results reveal that our model can keep the target object within a certain region in the camera view.
The document discusses higher dimensional reconstruction techniques for medical imaging. It begins with a review of 3D reconstruction and the mathematical modeling using the Radon transform. It then describes 4D, 5D and 6D reconstruction which add additional dimensions of time, cardiac phase and respiration to the 3D spatial reconstruction. Higher dimensional reconstruction allows for dynamic imaging but introduces additional challenges from increased noise, bias and variance. The document explores techniques like iterative reconstruction to address these issues and improve accuracy. Real patient data is used to demonstrate the reconstruction methods.
Blind separation of complex-valued satellite-AIS data for marine surveillance...IJECEIAES
In this paper, the problem of the blind separation of complex-valued Satellite-AIS data for marine surveillance is addressed. Due to the specific properties of the sources under consideration: they are cyclo-stationary signals with two close cyclic frequencies, we opt for spatial quadratic time-frequency domain methods. The use of an additional diversity, the time delay, is aimed at making it possible to undo the mixing of signals at the multi-sensor receiver. The suggested method involves three main stages. First, the spatial generalized mean Ambiguity function of the observations across the array is constructed. Second, in the Ambiguity plane, Delay-Doppler regions of high magnitude are determined and Delay-Doppler points of peaky values are selected. Third, the mixing matrix is estimated from these Delay-Doppler regions using our proposed non-unitary joint zero-(block) diagonalization algorithms as to perform separation.
This chapter discusses the response spectrum method of seismic analysis. Response spectra are curves that show the maximum response of single-degree-of-freedom oscillators with different periods when subjected to earthquake ground motion. The chapter defines different types of response spectra (displacement, velocity, acceleration) and their relationships. It also discusses factors that influence response spectra and sources of error in evaluating response spectra. Finally, it provides the response spectra for the 1940 El Centro earthquake and an example problem to calculate maximum response using the response spectra.
This document summarizes various techniques for analytic data visualization of large datasets, including scatterplots, biplots, regression biplots, kernel PCA, and support vector machine (SVM) biplots. It discusses how each technique can be used to visualize relationships between multiple variables and observations from large datasets in 2 or 3 dimensions. Examples applying several of the techniques to real datasets are also presented.
Photoacoustic tomography based on the application of virtual detectorsIAEME Publication
This document discusses using virtual detectors to improve photoacoustic tomography (PAT) image reconstruction when full scanning data is unavailable. It proposes interpolation and compressed sensing methods to generate virtual detector data and increase the number of measurements. Simulation results show applying these methods to preprocessed photoacoustic data significantly improves the peak signal-to-noise ratio of reconstructed images compared to direct reconstruction with limited detectors. Dictionary-based compressed sensing provides the best performance by learning an over-complete dictionary to sparsify signals. The methods allow better quality PAT imaging when hardware and spatial constraints limit actual detector positions and sampling angles.
1) The document describes a real-time 3D MR acquisition technique for capturing respiratory motion during simultaneous PET-MR imaging to correct for motion in the PET reconstruction.
2) A fast 3D radial projection sequence was used with a 2-parameter golden angle scheme to continuously and uniformly sample k-space without repeating projections.
3) Image reconstruction of sliding window frames used sparse reconstruction to generate motion images, and 4D registration analyzed all frames to determine the 3D motion vector field.
This document discusses different types of structural response spectra used to analyze how structures respond to dynamic loads like earthquakes. It defines static load response, dynamic load response, and equations of motion. It explains D'Alembert's principle of dynamic equilibrium and how response depends on natural frequency and damping ratio. It then describes response time histories obtained from accelerographs and how response spectra are developed based on maximum deformation of single-degree-of-freedom systems subjected to ground motions. Finally, it defines pseudo-velocity, pseudo-acceleration response spectra and how each spectrum provides a meaningful physical quantity - deformation, strain energy, or equivalent static force.
This document describes the development of a "smart pebble" device using MEMS sensors to monitor sediment transport in river beds. The smart pebble is designed to be about 2-3 cm in diameter, operate underwater, and autonomously record motion data. It uses accelerometers and gyroscopes to measure motion and orientation. A mixed-signal approach is used to process the sensor data, employing analog circuits like multipliers combined with a digital processor. Experimental tests showed the mixed-signal design provided reasonably accurate motion data compared to encoder measurements, demonstrating the feasibility of the smart pebble concept for further sediment transport research.
Hyperspectral Imaging Camera using Wavefront??? ?????
This document describes a new approach for hyperspectral imaging using wavefront division interference. The approach uses a spatial light modulator placed in the exit pupil of an imaging system to divide the wavefront from each object point into two parts with a variable phase delay. As the phase delay is changed, an interferogram is obtained for each wavelength, allowing the spectrum at each point to be determined. The approach converts a general imaging system into a hyperspectral imaging system with only a minor impact on optical performance. A prototype optical system was built to demonstrate this new wavefront division interference approach to hyperspectral imaging.
Weak Gravitational Lensing and Gauss-Bonnet Theorem discusses using the Gauss-Bonnet theorem to calculate light deflection angles in various spacetime geometries, including:
1. Calculating the deflection angle of light near a Schwarzschild black hole using the optical geometry and Gaussian curvature.
2. Computing the deflection of light by dyonic wormholes in Einstein-Maxwell-Dilaton theory and showing the deflection depends on the electric, magnetic, and dilaton charges.
3. Finding the deflection angle of light is inversely proportional to the Rindler acceleration for a Rindler modified Schwarzschild black hole.
This document summarizes a study that used sigmoidal parameterization and Metropolis-Hasting (MH) inversion to estimate seismic velocity models from traveltime data. The key points are:
1) Sigmoidal functions were used to parameterize discontinuous velocity fields, allowing for sharp variations while maintaining continuity.
2) Ray tracing and the MH algorithm were used to invert traveltime data and estimate model parameters.
3) Tests on synthetic models showed the MH method produced higher resolution velocity models that better fit the observed traveltime data, compared to other global optimization methods like very fast simulated annealing.
ESTIMATE OF THE HEAD PRODUCED BY ELECTRICAL SUBMERSIBLE PUMPS ON GASEOUS PETR...ijaia
This paper reports successful development of an exact and an efficient radial basis function network (RBFN) model to estimate the head of gaseous petroleum fluids (GPFs) in electrical submersible pumps (ESPs). Head of GPFs in ESPs is now often estimated using empirical models. Overfitting and its consequent lack of model generality data is a potentially serious issue. In addition, available data series is fairly small, including the results of 110 experiments. All these limits were considered in RBFN design process, and highly accurate RBFNs were developed and cross validated.
The document discusses the finite-difference time-domain (FDTD) method for modeling computational electrodynamics and solving Maxwell's equations numerically. It explains that the FDTD method works by discretizing Maxwell's equations using central difference approximations in space and time. The electric and magnetic fields are then iteratively solved on a grid to simulate electromagnetic wave propagation. A key aspect is the Yee lattice, which spatially staggers the electric and magnetic field components to improve accuracy. An example 1D FDTD MATLAB code is also included to demonstrate the technique.
The centerless circular array (CCA) method can be used to estimate phase velocities of Rayleigh waves from microtremor records obtained using an array of seismic sensors placed around a circumference. The method analyzes the power spectral densities of synthesized waveforms to obtain a spectral ratio, from which phase velocities can be inferred. Noise limits the resolution of the CCA method at long wavelengths. A new method is proposed to quantitatively evaluate the noise-to-signal ratio using the coherence between array seismograms, allowing estimation of the longest resolvable wavelength. Analysis of field data using larger arrays confirms the applicability and high performance of the CCA method into surprisingly long wavelengths.
The document describes a discrete-time Kalman filter implemented in MATLAB to estimate the position of an underwater vehicle using sensor measurements. It presents the state space modeling equations used in the filter, including modifying the state vector to address non-linearities in the direction measurement. Simulation results using a carefully designed trajectory show the filter provides estimates with errors generally within a few meters for position, a few centimeters for velocity bias, and a few meters for range over 1000 iterations.
IT IS ABOUT FUSION OF TWO NATURE INSPIRED OPTIMIZATION ALGORITHM(S).THE FIRST ONE IS GRAVITATIONAL SEARCH ALGORITHM(GSA) BASED ON NEWTONS UNIVERSAL LAW OF GRAVITATION AND OTHER ONE i.e; BIOGEOGRAPHY BASED OPTIMIZATION(BBO) BASED ON BIOGEOGRAPGY (THE STUDY OF SPECIES IN A PARTICULAR HABITAT).
This document summarizes a presentation on using statistical models to characterize textures in high resolution transmission electron microscopy (TEM) images. It proposes using the statistical invariances and geometry (SIGMA) modeling approach and auto-regressive fractional Brownian field (ARFBF) models. Specifically, it discusses:
1) Modeling textures using generalized fractional Brownian fields, auto-regressive models, and 2-factor fractional Brownian fields.
2) Methods for estimating Hurst parameters and pole locations from these models.
3) Applying the ARFBF model to characterize TEM images by estimating parameters from the image spectrum and modeling residuals.
This document discusses elastic earthquake response spectra. It defines different types of response spectra including relative displacement, velocity, and acceleration spectra. It explains that response spectra give the maximum response of single-degree-of-freedom systems subjected to earthquakes and indicate the frequency distribution of seismic energy. The document discusses exact and pseudo response spectra. It also introduces the tripartite representation of response spectra and describes simplified design response spectra proposed by Housner and Newmark and Hall.
Measurement-induced long-distance entanglement with optomechanical transducersOndrej Cernotik
Although superconducting systems provide a promising platform for quantum computing, their networking poses a challenge as they cannot be interfaced to light---the medium used to send quantum signals through channels at room temperature. We show that mechanical oscillators can mediated such coupling and light can be used to measure the joint state of two distant qubits. The measurement provides information on the total spin of the two qubits such that entangled qubit states can be postselected. Entanglement generation is possible without ground-state cooling of the mechanical oscillators for systems with optomechanical cooperativity moderately larger than unity; in addition, our setup tolerates a substantial transmission loss. The approach is scalable to generation of multipartite entanglement and represents a crucial step towards quantum networks with superconducting circuits.
A Study of Non-Gaussian Error Volumes and Nonlinear Uncertainty Propagation f...Justin Spurbeck
The ever-growing resident space object population poses a continual threat in that a hyper velocity impact is likely to be catastrophic to an active satellite. To avoid these scenarios, space operators compute a probability of collision metric for each potential conjunction. Uncertainty trends are studied in the conjunction plane and operational decisions to mitigate any high-risk situations are made based off this information. There are many methods of uncertainty propagation and probability of collision formulations and knowledge of their realism is required to maintain a sustainable space environment. Thus, this research studies the effect of Chan, Alfano, Foster, Gaussian mixture, and Monte Carlo probability of collision calculations and their correlation to uncertainty realism metrics. The linear, unscented transform, entropy-based, and Monte Carlo propagation techniques are utilized alongside the collision calculations and it is shown that there are important correlations any space operator should be aware of to support maintenance of a healthy spacecraft.
El documento describe el proceso de búsqueda en bases de datos como CINHAL y PUBMED. Explica cómo usar DECS para encontrar términos médicos relevantes, realizar búsquedas en las bases de datos utilizando estrategias de búsqueda, seleccionar y guardar artículos, y exportarlos a Mendeley para generar citas bibliográficas en formato Vancouver.
Blind separation of complex-valued satellite-AIS data for marine surveillance...IJECEIAES
In this paper, the problem of the blind separation of complex-valued Satellite-AIS data for marine surveillance is addressed. Due to the specific properties of the sources under consideration: they are cyclo-stationary signals with two close cyclic frequencies, we opt for spatial quadratic time-frequency domain methods. The use of an additional diversity, the time delay, is aimed at making it possible to undo the mixing of signals at the multi-sensor receiver. The suggested method involves three main stages. First, the spatial generalized mean Ambiguity function of the observations across the array is constructed. Second, in the Ambiguity plane, Delay-Doppler regions of high magnitude are determined and Delay-Doppler points of peaky values are selected. Third, the mixing matrix is estimated from these Delay-Doppler regions using our proposed non-unitary joint zero-(block) diagonalization algorithms as to perform separation.
This chapter discusses the response spectrum method of seismic analysis. Response spectra are curves that show the maximum response of single-degree-of-freedom oscillators with different periods when subjected to earthquake ground motion. The chapter defines different types of response spectra (displacement, velocity, acceleration) and their relationships. It also discusses factors that influence response spectra and sources of error in evaluating response spectra. Finally, it provides the response spectra for the 1940 El Centro earthquake and an example problem to calculate maximum response using the response spectra.
This document summarizes various techniques for analytic data visualization of large datasets, including scatterplots, biplots, regression biplots, kernel PCA, and support vector machine (SVM) biplots. It discusses how each technique can be used to visualize relationships between multiple variables and observations from large datasets in 2 or 3 dimensions. Examples applying several of the techniques to real datasets are also presented.
Photoacoustic tomography based on the application of virtual detectorsIAEME Publication
This document discusses using virtual detectors to improve photoacoustic tomography (PAT) image reconstruction when full scanning data is unavailable. It proposes interpolation and compressed sensing methods to generate virtual detector data and increase the number of measurements. Simulation results show applying these methods to preprocessed photoacoustic data significantly improves the peak signal-to-noise ratio of reconstructed images compared to direct reconstruction with limited detectors. Dictionary-based compressed sensing provides the best performance by learning an over-complete dictionary to sparsify signals. The methods allow better quality PAT imaging when hardware and spatial constraints limit actual detector positions and sampling angles.
1) The document describes a real-time 3D MR acquisition technique for capturing respiratory motion during simultaneous PET-MR imaging to correct for motion in the PET reconstruction.
2) A fast 3D radial projection sequence was used with a 2-parameter golden angle scheme to continuously and uniformly sample k-space without repeating projections.
3) Image reconstruction of sliding window frames used sparse reconstruction to generate motion images, and 4D registration analyzed all frames to determine the 3D motion vector field.
This document discusses different types of structural response spectra used to analyze how structures respond to dynamic loads like earthquakes. It defines static load response, dynamic load response, and equations of motion. It explains D'Alembert's principle of dynamic equilibrium and how response depends on natural frequency and damping ratio. It then describes response time histories obtained from accelerographs and how response spectra are developed based on maximum deformation of single-degree-of-freedom systems subjected to ground motions. Finally, it defines pseudo-velocity, pseudo-acceleration response spectra and how each spectrum provides a meaningful physical quantity - deformation, strain energy, or equivalent static force.
This document describes the development of a "smart pebble" device using MEMS sensors to monitor sediment transport in river beds. The smart pebble is designed to be about 2-3 cm in diameter, operate underwater, and autonomously record motion data. It uses accelerometers and gyroscopes to measure motion and orientation. A mixed-signal approach is used to process the sensor data, employing analog circuits like multipliers combined with a digital processor. Experimental tests showed the mixed-signal design provided reasonably accurate motion data compared to encoder measurements, demonstrating the feasibility of the smart pebble concept for further sediment transport research.
Hyperspectral Imaging Camera using Wavefront??? ?????
This document describes a new approach for hyperspectral imaging using wavefront division interference. The approach uses a spatial light modulator placed in the exit pupil of an imaging system to divide the wavefront from each object point into two parts with a variable phase delay. As the phase delay is changed, an interferogram is obtained for each wavelength, allowing the spectrum at each point to be determined. The approach converts a general imaging system into a hyperspectral imaging system with only a minor impact on optical performance. A prototype optical system was built to demonstrate this new wavefront division interference approach to hyperspectral imaging.
Weak Gravitational Lensing and Gauss-Bonnet Theorem discusses using the Gauss-Bonnet theorem to calculate light deflection angles in various spacetime geometries, including:
1. Calculating the deflection angle of light near a Schwarzschild black hole using the optical geometry and Gaussian curvature.
2. Computing the deflection of light by dyonic wormholes in Einstein-Maxwell-Dilaton theory and showing the deflection depends on the electric, magnetic, and dilaton charges.
3. Finding the deflection angle of light is inversely proportional to the Rindler acceleration for a Rindler modified Schwarzschild black hole.
This document summarizes a study that used sigmoidal parameterization and Metropolis-Hasting (MH) inversion to estimate seismic velocity models from traveltime data. The key points are:
1) Sigmoidal functions were used to parameterize discontinuous velocity fields, allowing for sharp variations while maintaining continuity.
2) Ray tracing and the MH algorithm were used to invert traveltime data and estimate model parameters.
3) Tests on synthetic models showed the MH method produced higher resolution velocity models that better fit the observed traveltime data, compared to other global optimization methods like very fast simulated annealing.
ESTIMATE OF THE HEAD PRODUCED BY ELECTRICAL SUBMERSIBLE PUMPS ON GASEOUS PETR...ijaia
This paper reports successful development of an exact and an efficient radial basis function network (RBFN) model to estimate the head of gaseous petroleum fluids (GPFs) in electrical submersible pumps (ESPs). Head of GPFs in ESPs is now often estimated using empirical models. Overfitting and its consequent lack of model generality data is a potentially serious issue. In addition, available data series is fairly small, including the results of 110 experiments. All these limits were considered in RBFN design process, and highly accurate RBFNs were developed and cross validated.
The document discusses the finite-difference time-domain (FDTD) method for modeling computational electrodynamics and solving Maxwell's equations numerically. It explains that the FDTD method works by discretizing Maxwell's equations using central difference approximations in space and time. The electric and magnetic fields are then iteratively solved on a grid to simulate electromagnetic wave propagation. A key aspect is the Yee lattice, which spatially staggers the electric and magnetic field components to improve accuracy. An example 1D FDTD MATLAB code is also included to demonstrate the technique.
The centerless circular array (CCA) method can be used to estimate phase velocities of Rayleigh waves from microtremor records obtained using an array of seismic sensors placed around a circumference. The method analyzes the power spectral densities of synthesized waveforms to obtain a spectral ratio, from which phase velocities can be inferred. Noise limits the resolution of the CCA method at long wavelengths. A new method is proposed to quantitatively evaluate the noise-to-signal ratio using the coherence between array seismograms, allowing estimation of the longest resolvable wavelength. Analysis of field data using larger arrays confirms the applicability and high performance of the CCA method into surprisingly long wavelengths.
The document describes a discrete-time Kalman filter implemented in MATLAB to estimate the position of an underwater vehicle using sensor measurements. It presents the state space modeling equations used in the filter, including modifying the state vector to address non-linearities in the direction measurement. Simulation results using a carefully designed trajectory show the filter provides estimates with errors generally within a few meters for position, a few centimeters for velocity bias, and a few meters for range over 1000 iterations.
IT IS ABOUT FUSION OF TWO NATURE INSPIRED OPTIMIZATION ALGORITHM(S).THE FIRST ONE IS GRAVITATIONAL SEARCH ALGORITHM(GSA) BASED ON NEWTONS UNIVERSAL LAW OF GRAVITATION AND OTHER ONE i.e; BIOGEOGRAPHY BASED OPTIMIZATION(BBO) BASED ON BIOGEOGRAPGY (THE STUDY OF SPECIES IN A PARTICULAR HABITAT).
This document summarizes a presentation on using statistical models to characterize textures in high resolution transmission electron microscopy (TEM) images. It proposes using the statistical invariances and geometry (SIGMA) modeling approach and auto-regressive fractional Brownian field (ARFBF) models. Specifically, it discusses:
1) Modeling textures using generalized fractional Brownian fields, auto-regressive models, and 2-factor fractional Brownian fields.
2) Methods for estimating Hurst parameters and pole locations from these models.
3) Applying the ARFBF model to characterize TEM images by estimating parameters from the image spectrum and modeling residuals.
This document discusses elastic earthquake response spectra. It defines different types of response spectra including relative displacement, velocity, and acceleration spectra. It explains that response spectra give the maximum response of single-degree-of-freedom systems subjected to earthquakes and indicate the frequency distribution of seismic energy. The document discusses exact and pseudo response spectra. It also introduces the tripartite representation of response spectra and describes simplified design response spectra proposed by Housner and Newmark and Hall.
Measurement-induced long-distance entanglement with optomechanical transducersOndrej Cernotik
Although superconducting systems provide a promising platform for quantum computing, their networking poses a challenge as they cannot be interfaced to light---the medium used to send quantum signals through channels at room temperature. We show that mechanical oscillators can mediated such coupling and light can be used to measure the joint state of two distant qubits. The measurement provides information on the total spin of the two qubits such that entangled qubit states can be postselected. Entanglement generation is possible without ground-state cooling of the mechanical oscillators for systems with optomechanical cooperativity moderately larger than unity; in addition, our setup tolerates a substantial transmission loss. The approach is scalable to generation of multipartite entanglement and represents a crucial step towards quantum networks with superconducting circuits.
A Study of Non-Gaussian Error Volumes and Nonlinear Uncertainty Propagation f...Justin Spurbeck
The ever-growing resident space object population poses a continual threat in that a hyper velocity impact is likely to be catastrophic to an active satellite. To avoid these scenarios, space operators compute a probability of collision metric for each potential conjunction. Uncertainty trends are studied in the conjunction plane and operational decisions to mitigate any high-risk situations are made based off this information. There are many methods of uncertainty propagation and probability of collision formulations and knowledge of their realism is required to maintain a sustainable space environment. Thus, this research studies the effect of Chan, Alfano, Foster, Gaussian mixture, and Monte Carlo probability of collision calculations and their correlation to uncertainty realism metrics. The linear, unscented transform, entropy-based, and Monte Carlo propagation techniques are utilized alongside the collision calculations and it is shown that there are important correlations any space operator should be aware of to support maintenance of a healthy spacecraft.
El documento describe el proceso de búsqueda en bases de datos como CINHAL y PUBMED. Explica cómo usar DECS para encontrar términos médicos relevantes, realizar búsquedas en las bases de datos utilizando estrategias de búsqueda, seleccionar y guardar artículos, y exportarlos a Mendeley para generar citas bibliográficas en formato Vancouver.
The student learned new skills for creating a magazine using Photoshop, including adjusting brightness and contrast and angling images. They also learned how to use Blogger to create posts, upload images and videos, and change text size. Creating the indie music magazine taught the student how to use presentation software to show responses and evaluations. Overall, the student gained new technical skills using various software that allowed them to construct a professional magazine and present their work in a polished manner.
The document discusses the use of shunt active filters to mitigate current harmonics in power systems. It analyzes the performance of a shunt active filter controlled by a PI controller and fuzzy logic controller (FLC) under normal and increased load conditions with balanced and unbalanced source voltages. The main points are:
A) Shunt active filters inject compensating current to make the source current sinusoidal and maintain unity power factor.
B) Both PI and FLC controllers perform well under balanced voltages but FLC provides better compensation under unbalanced voltages.
C) The FLC with a triangular membership function offers superior results compared to the PI controller in mitigating current harmonics.
Fiona Samadan is seeking a position that allows her to utilize her skills and experience. She has over 10 years of experience in human resources, finance, administration, and insurance. Her background includes roles processing employee separations and benefits, managing medical insurance administration, and handling various financial and accounting tasks. She is proficient in Microsoft Office, banking systems, and has knowledge of UAE's life and medical insurance systems.
The document discusses various topics related to human nutrition:
- It describes the essential nutrients that must be consumed as part of our diet, including water, lipids, some amino acids, and vitamins and minerals.
- It then covers digestion, including the roles of the stomach, small intestine, liver, and heart. The stomach aids in protein digestion through gastric juices. The small intestine completes digestion with enzymes from the pancreas and bile from the liver. The liver performs many functions including detoxification and production of proteins and bile. The heart pumps blood throughout the body.
this presentation may help you to get better information on what is urbanization, its pros and cons globally as well as special emphasis on Indian Economy with adequate statistics.
hope you liked it.
M-commerce (mobile commerce) is the buying and selling of goods and services through wireless handheld devices., and it is known as next-generation e-commerce.
The document discusses the importance of partnership working when supporting children's development and needs. It explains that partnership working involves collaborating with professionals both within and outside of a setting, as well as with parents and carers, to share information and ensure continuity of care for children. The document also addresses working with different family structures and the benefits of effective communication when working in partnerships.
Fundamentos Epistemológicos de la Psicología Fenomenológica Existencial - De ...SergioMontoya
El enfoque fenomenológico existencial en Psicología propone que debemos preocuparnos por comprender el sentido de la experiencia del ser humano, antes que por preocuparnos tanto por explicar su conducta y validar cuantitativamente su experiencia
Boston Best Places to Work Roadshow | HubSpotGlassdoor
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2. A. V. NARASIMHADHAN ET AL. 137
formed projections; involving parameters of the virtual
acquisition geometry but the aforementioned reconstruc-
tion formula is convoyed with a position-dependent back-
projection weight. Since large amount of data needs be
processed in dynamic studies, the implementation of the
FBP formula for dynamic CT proposed by Roux et al.
[10] will consume more time than it’s counterpart (static
case). The solution to eliminate the position-dependent
back-projection weight in the fan-beam FBP formula,
proposed by Noo. et al. [11] inspired by [12] in a static
2-D CT was given in [13]. In this paper, we reduce the
computational cost of the fan-beam FBP reconstruction
formula for a 2-D dynamic CT proposed by Roux. et al.,
by eliminating the position-dependent back-projection
weight, by choosing the weighting function similar to the
one proposed in [13] for compensating time-dependent
rotational, uniform scaling and translational deformations.
By uniform scaling, we mean that the scaling transfor-
mation scales the object with the same magnitude along
both the orthogonal reference co-ordinates. Thus for the
above mentioned deformations, our formula will con-
sume less time than the one proposed by Roux et al., due
to the elimination of computationally expensive back-
projection weight.
We follow the sequential approach listed below to ad-
dress the issues raised in the paper. 1) Admissibility con-
dition to reconstruct the object from the projections ac-
quired during it’s deformation (affine). 2) Reconstruction
formula for a dynamic CT, compensating the time-de-
pendent affine deformation. 3) Incorporating the tech-
niques in the above formula to eliminate back-projection
weight. 4) Simulating the idea presented in the paper.
2. Theory
Consider an object having strong dynamic nature and
thus it deforms as a function of time during the data ac-
quisition process. Let the object be denoted as tf at
time and 0t f at time 0 , where 0 is the reference
time, where the object is assumed to be stationery. t
t t
be the transformation that maps the real object at par-
ticular time to the reference time 0t as shown in
Figure 1. Therefore t transforms the object from “real
state” to “reference state”.
t
0tf f x x
(1)
11 12 1
21 22 2
where and
t t
t
A
a t a t b t
A
a t a t b t
t
t
x x b
b
Thus, each real X-ray path on the evolving object is
associated with a virtual X-ray path on the reference
object, giving rise to a virtual acquisition geometry.
Since affine transformations preserve intersection, each
Figure 1. Fan-beam geometry: transformation of dynamic
object projections to reference object projections (Courtesy:
Roux et al. [10]).
fan beam projection is transformed into another fan beam
projection.
In a fan beam geometry, the parameter uniquely
determines one set of projection and also gives an
understanding of the source location. Since is varied
with respect to time for acquiring all the projections,
therefore can be replaced with
t
t [10]. Mathemati-
cally,
0
, dg l
a l (2)
,g be the dynamic fan-beam projection data
collected with a circular scan trajectory given by
T
0 0cos sinR R a for a dynamic object f
where is the radius of the source trajectory.0R l
and 1
S where is the set of unit vectors in .1
S 2
2.1. Admissibility Conditions on the Deformation
for Fan-Beam Case
Roux et al. have proposed a derivation of admissibility
conditions based on generalization of Hamaker et al. [14]
to get a relation between the Hilbert Transform of the
acquired fan-beam data and the Hilbert transform of the
reference object projections. The result is given below:
0
T1
, ,
det
OH H
s
p s g A
A
a n
n n (3)
where OH is the Hilbert Filtered Parallel beam Pro-
jections of a ray perpendicular to n and the distance of s
from the origin along n, thus Hilbert transform is in the
direction of n whereas
p
Hg
is the Hilbert filtered fan-
beam projections along the direction T
A andn 0 a
is the virtual source trajectory given by:
0 a a .
On modification of the condition stated by Noo et al.
[11] (Noo’s formula will be briefed in the next section)
for static case, the following admissibility condition is
deduced for the dynamic CT: Region of interest (ROI) in
Open Access OJMI
3. A. V. NARASIMHADHAN ET AL.138
a dynamic object can be successfully reconstructed if all
lines passing through the neighborhood of ROI intersects
the virtual trajectory 0 a [10].
2.2. Fan-Beam Reconstruction Formula Based
on Hilbert Filtering
A new class of algorithm based on Hilbert FBP (HFBP)
has been derived [11] from the relation given in [14] for
equi-angular static fan-beam projections, which is given
by
0
0 0
2
0 0 0 ,
1 1
d , ,
2
m
F
f
w g
x
x
x a
(4)
where
, d sin ,
m
m
m m
F Hg h g
,
(5)
is the angle characterizing the ray that diverges from
0 a and contains , the projection data is charac-
terized by
0x
and
, ,m
g g , (6)
and are defined through parametrization with
respect to
n
and
cos sin and sin cos ,u v u v e e n e e (7)
,w is the redundancy weight and
0
0
0 0
, arctan v
uR
x e
x
x e
(8)
where 0 is the point, to be reconstructed, on the ref-
erence object.
x
Two unit orthogonal vectors u and given in the
above equation are described as follows:
e
ve
T
sin cosv e
, which is tangent to the
source trajectory at 0 a
T
cos sinu
and
e
, which is opposite to the
direction of 0 a .
The Hilbert FBP divergent beam reconstruction algo-
rithms have spatially more uniform resolution and noise
performance, and reduced divergent beam artefacts as a
result of
0 0
1
a x
backprojection weight instead of
the
2
0 0
1
a x
weight in ramp FBP algorithm [15].
Noise non uniformity is appeared in the reconstructed
image since ramp FBP algorithm is implemented using
shift invariant filter [16]. Noise uniformity is achieved
with shift variant filter [17]. Recently, two fan-beam al-
gorithms [13,18] with no backprojection weight have
been derived to address the position or distance depend-
ent non-uniformity of resolution and noise variance by
eliminating the backprojection weight. Extension of these
two algorithms for cone-beam tomography has been
given in [19].
2.3. Fan-Beam Reconstruction Formula with No
Backprojection Weight
As discussed earlier, fan-beam FBP reconstruction for-
mula (4) is convoyed with a position dependent weight,
thus increasing the computational cost of the overall al-
gorithm. The solution to eliminating this weight has been
given in [13] by choosing a weighting function propor-
tional to the back-projection weight
0 0
0
,
2 cos
w
R
x a
(9)
and such that
, ,c cw w 1 (10)
where c represents a complementary source location
such that 0 a , 0 andx 0 ca are collinear and
c is the angle characterizing the fan-beam ray emanat-
ing from 0 ca and containing . Thus the value of
radon transform is same for the rays characterized by
x
, and ,c c . Therefore, by choosing the weight-
ing function (9), the position dependent back-projection
weight is eliminated, yielding the below given formula:
2
0 0
00
1 1
d , .
4 cos
m
Ff g
R
x (11)
This is the fan-beam FBP reconstruction algorithm
with no back-projection weight for equi-angular curved
detector geometry.
3. Incorporation of Motion Model in Static
Fan-Beam FBP Reconstruction Formula
In this section, we shall brief the readers about the mo-
tion compensation algorithm given in [10] to tackle mo-
tion artefacts arising due to affine deformations during
the data acquisition process. This formula was derived by
incorporating motion model or deformation model into
the fan-beam FBP reconstruction formula given in [11].
Since the static formula is convoyed with a position de-
pendent back-projection weight, therefore the affine de-
formation compensation formula for dynamic CT is also
computationally expensive due to the back-brojection
weight inhereted from formula given in [11]. We present
a technique to eliminate this position dependent back-
projection weight for translational, uniform scaling and
rotational deformation by choosing the weighting func-
Open Access OJMI
4. A. V. NARASIMHADHAN ET AL. 139
tion similar to the one chosen in [13] for the static case.
3.1. Reconstruction Formula with
Backprojection Weight: Compensation of
Affine Deformation
Let ,g be the deformed projection data. A fan-
beam ray is parametrized by the parameters and ,
where is the angle between a ray of interest and the
line connecting source position to the origin. With re-
ference to the dynamic object, the normal of a ray, pass-
ing through a point to be reconstructed, is denoted asx
, , where is the angle of the ray connecting
source and point to be reconstructed with in the fan:
v . For each real x-ray,
diverging from the vertex point, there exist a virtual
x-ray path given by,
, s in cosu e e
0
0 0
x a x a
x a x a
where
x a
x a
is the unit vector along the real x-ray
path and
0 0
0 0
x a
x a
is the unit vector along the
virtual x-ray path.
Consider
T
sin cos as the normal to the
virtual ray, joining the source and the point to be
reconstructed on the reference object.
With Reference [10], we directly write the following
relation,
T
, T
A
A
.
(12)
And the fan-beam reconstruction formula from de-
formed projection data is given by
0
0
0
0 0
* ,
1 1
d , ,
2
m
F
f
w g
x
x
x
a x
(13)
where
, , ,
, ,
m m
F wH
m
wH
g g
g
(14)
where, the set 0
x is defined as:
*
x 0,π
0 0 * 0 x a x with
1
1 T
A
(15)
where
T
T
. .
. .
v u
u v
A A
A A
e e
e e
,
(16)
and
T
, det ,m m ang
wH Hg A A g h
(17)
sin
ang
Hh
Hh
(18)
where Hh is the impulse response of Hilbert Filter.
For static fan-beam case, the virtual trajectory and the
real trajectory is the same, similarly the reference object
is the same as dynamic object. Thus , wheredA I dI
is the Identity matrix.
3.2. Reconstruction Formula with No
Backprojection Weight: Compensation for
Translational, Uniform Scaling and
Rotational Deformations
In this section, we use the weighting function (9), and
eliminate the position dependent back-projection weight
0 01 x a in the image reconstruction formula
given by Equation (13). The weighting
*
*
0
, ,
2 cos
w
R
a
x
x
(19)
Equations (9), (10), the above Equation (19) is valid as it
normalizes to one, the contribution from any line through
within the FOV. The back projection weight in the
virtual acquisition geometry is given by:
x
0 0
1
a x
(20)
where
0 0and = a a x x
0 0and .A A a a b x x b (21)
Substituting the result obtained in Equation (21) to the
back-projection weight we get,
0 0
1 1
.
AA A
a xa xa b x b
1
(22)
The key point to observe from Equation (22) is that the
back-projection weight is independent of translational0 such that,
Open Access OJMI
5. A. V. NARASIMHADHAN ET AL.140
and rotational deformation, it only depends on scaling
and shearing. The formula (13) compensates for time de-
pendent affine deformation but is convoyed with a posi-
tion dependent weight as discussed earlier. Therefore, if
the object being imaged is subjected to translational or
rotational deformation or both, then the term a x
in the weighting function (19) does not change (i.e.
0 0 ), but scaling and shearing
affects the back-projection weight as suggested by Equa-
tion (21). We propose to eliminate the position dependent
back-projection weight for rotational, uniform scaling
and translational deformations or their combinations.
a x a x
Concretely, for a translational deformation, the matrix
is chosen as
1 0
0 1
tr
A A
(23)
and the b can be chosen any vector since it does not
effect the modification process of weighting term (22). In
case of only rotational deformation, the transformation is
done with a matrix given by
cos sin
sin cos
R
A A
. (24)
therefore
0 0
1 1
R
A
a x a xa x
1
So, back-projection weight does not change in case of
rotational deformation. Now we shall discuss about uni-
form scaling wherein the back-projection weight changes.
For uniform scaling deformation, sc
A A
0
0
sc
A
. (25)
therefore,
0 0
1 1
sc
A
a x a xa x
1
(26)
Thus, by employing the weighting function (19) and
the Equation (26) in Equation (13) we deduce the fol-
lowing fan-beam FBP reconstruction formula:
0
0 0
*0 ,0
1 1
, d
2 2 cos
m
F
w
x
f g
R
x
x
(27)
where set is defined as: 0w
x
* 0 *0,π : range , 2w c c k x
where 1,2,3,k and c is the initial value of .
Equation (27) gives us the exact image reconstruction
formula for compensating rotational and translational
deformation during acquisition of equi-angular fan beam
projections without any position dependent back-projec-
tion weight.
3.3. Salient Features of Proposed Algorithm
Since the technique involves derivative of the Hilbert
filtered projection data, we have an advantage in terms of
noise performance [20,21]. The implementation of modi-
fied formula exhibits less variance compared to the fan-
beam algorithm with no backprojection weight since
more implementation blocks in modified formula. It can
be mentioned here that the modified formula gives better
computational efficiency than the unmodified for dy-
namic case. However, we shall give execution time form
both algorithm in the simulation section.
4. Simulation Results
We simulate projection of low contrast Shep Logan
phantom by considering the static as well as rotational
and scaled deformed object. The scan parameters which
we have used for simulation have been given Table 1.
We have chosen A or tA as diagonal matrix with
following parameters 11 22a a
0.2 0.1sin . And, = 0 0.2b is chosen as
constant term with respect to time. Figure 2 shows the
sinogram of original Shep Logan and deformed Shep
Logan phantom. Firstly, the Shep Logan phantom is re-
constructed using the fan-beam algorithm with no back-
projection weight for a static object, which inturn yields
an exact reconstruction of the Shep Logan Phantom (Fig-
ure 3(b)). Secondly, we reconstruct the Shep Logan Phan-
tom from rotationally deformed data using fan-beam al-
gorithm with no backprojection weight and our presented
algorithm (Figures 3(c) and (d)). The observations com-
pletely abide with the theoretical and mathematical for-
mulations and the Shep Logan phantom is exactly recon-
structed. It is clearly observed from the Figure 3 that our
proposed reconstruction algorithm removes the rotational
motion artefacts.
4.1. Computational Complexity
The only difference between the Equations (27) and (13)
Table 1. Fan-beam imaging parameters used in simulations.
Imaging parameter Value
Number of pixels 2562
Object radius 1.0
Scanning radius 2.4
Source to detector distance 4.8
Number of source positions per turn 450
Number of detectors 460
Open Access OJMI
6. A. V. NARASIMHADHAN ET AL.
Open Access OJMI
141
(a) (b)
Figure 2. Sinogram: (a) Original Shep Logan phantom; (b) Deformed Shep Logan phantom.
(a) (b)
(c) (d)
Figure 3. Reconstruction of low contrast Shepp-Logan phantom, (a) Original phantom; (b) Using fan-beam reconstruction
algorithm with no backprojection weight from the static data; (c) Reconstruction with deformed data using fan-beam recon-
struction algorithm with no backprojection weight; (d) Reconstruction with deformed data using modified fan-beam algo-
ithm with no backprojection weight. rotation is used for each source position for dynamic projections. 30t r
7. A. V. NARASIMHADHAN ET AL.142
Table 2. Execution time (in seconds).
TotalFiltering Backprojection
Roux et al. 68.992algorithm 0.422 68.57
Proposed ithmalgor 0.46 20.44 21
is ndent and redundancy weight-the position depe weight
ing are replaced by the term
02 cosR
1
. This term can
be implemented before the b on. Hence, it is
clearly note that the reconstruction usi
ackprojecti
ng (27) takes less
ve presented the fan-beam recon-
with no backprojection weight for
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[1] M. Kachelries Electrocardiogram-
Correlated Im Subsecond Spira
time than the reconstruction using (13). However, we
have implemented proposed formula for dynamic projec-
tion using “C” complier. From the Table 2, it is clearly
observed that computational efficiency is achieved sig-
nificantly using modified fan-beam algorithm with no
backprojection weight than existing exact fan-beam re-
construction for dynamic projections data.
5. Conclusion
In this paper, we ha
struction algorithm
compensating time-dependent rotational deformation.
Since large amount of data is needed for dynamic CT,
elimination of position-dependent back-projection weight
from dynamic fan-beam reconstruction algorithm given
by Roux et al., facilitates more advantages in terms of
computational efficiency than the same in static CT. The
presented algorithm inherits the better noise and resolu-
tion characteristics same as fan-beam reconstruction al-
gorithm with no backprojection weight for static CT. It is
very clear from the above simulation results that the
proposed algorithm compensates for time-dependent ro-
tational, translational and scaling deformation and ex-
actly reconstructs the object, under consideration without
any motion artefacts.
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