The Experts below are selected from a list of 53820 Experts worldwide ranked by ideXlab platform
Rodney A Kennedy - One of the best experts on this subject based on the ideXlab platform.
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an optimal dimensionality multi shell Sampling Scheme with accurate and efficient transforms for diffusion mri
International Symposium on Biomedical Imaging, 2017Co-Authors: Alice P Bates, Zubair Khalid, Jason D Mcewen, Rodney A KennedyAbstract:This paper proposes a multi-shell Sampling Scheme and corresponding transforms for the accurate reconstruction of the diffusion signal in diffusion MRI by expansion in the spherical polar Fourier (SPF) basis. The Sampling Scheme uses an optimal number of samples, equal to the degrees of freedom of the band-limited diffusion signal in the SPF domain, and allows for computationally efficient reconstruction. We use synthetic data sets to demonstrate that the proposed Scheme allows for greater reconstruction accuracy of the diffusion signal than the multi-shell Sampling Scheme obtained using the generalised electrostatic energy minimisation (gEEM) method used in the Human Connectome Project. We also demonstrate that the proposed Sampling Scheme allows for increased angular discrimination and improved rotational invariance of reconstruction accuracy than the gEEM Scheme.
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an optimal dimensionality Sampling Scheme on the sphere with accurate and efficient spherical harmonic transform for diffusion mri
IEEE Signal Processing Letters, 2016Co-Authors: Alice P Bates, Zubair Khalid, Rodney A KennedyAbstract:We design a Sampling Scheme on the sphere and a corresponding spherical harmonic transform (SHT) for the measurement and reconstruction of the diffusion signal in diffusion magnetic resonance imaging (dMRI). By exploiting the antipodal symmetry property of the diffusion signal in the spectral (spherical harmonic) domain, we design a Sampling Scheme that attains the optimal number of samples, equal to the degrees of freedom required to represent the antipodally symmetric band-limited diffusion signal in the spectral domain. Compared with other Sampling Schemes that can be used with the optimal number of samples, we demonstrate, through numerical experiments, that the proposed Scheme enables more accurate computation of the SHT, and this accuracy is practically rotationally invariant. In addition, it results in more efficient computation of the SHT and storage of the diffusion signal.
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novel Sampling Scheme on the sphere for head related transfer function measurements
IEEE Transactions on Audio Speech and Language Processing, 2015Co-Authors: Alice P Bates, Zubair Khalid, Rodney A KennedyAbstract:This paper presents a novel Sampling Scheme on the sphere for obtaining head-related transfer function (HRTF) measurements and accurately computing the spherical harmonic transform (SHT). The Scheme requires an optimal number of samples, given by the degrees of freedom in the spectral domain, for the accurate representation of the HRTF that is band-limited in the spherical harmonic domain. The proposed Scheme allows for the samples to be easily taken over the sphere due to its iso-latitude structure and non-dense Sampling near the poles. In addition, the Scheme can be used when samples are not taken from the south polar cap region of the sphere as the HRTF measurements are not reliable in south polar cap region due to reflections from the ground. Furthermore, the Scheme has a hierarchical structure, which enables the HRTF to be analyzed at different audible frequencies using the same Sampling configuration. In comparison to the proposed Scheme, none of the other Sampling Schemes on the sphere simultaneously possess all these properties. We conduct several numerical experiments to determine the accuracy of the SHT associated with the proposed Sampling Scheme. We show that the SHT attains accuracy on the order of numerical precision ${(10^{ - 14}})$ when samples are taken over the whole sphere, both in the optimal sample placement and hierarchical configurations, and achieves an acceptable level of accuracy ${(10^{ - 5}})$ when samples are not taken over the south polar cap region of the sphere for the band-limits of interest. Simulations are used to show the accurate reconstruction of the HRTF over the whole sphere, including unmeasured locations.
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An Optimal Dimensionality Sampling Scheme on the Sphere for Antipodal Signals In Diffusion Magnetic Resonance Imaging
arXiv: Medical Physics, 2015Co-Authors: Alice P Bates, Zubair Khalid, Rodney A KennedyAbstract:We propose a Sampling Scheme on the sphere and develop a corresponding spherical harmonic transform (SHT) for the accurate reconstruction of the diffusion signal in diffusion magnetic resonance imaging (dMRI). By exploiting the antipodal symmetry, we design a Sampling Scheme that requires the optimal number of samples on the sphere, equal to the degrees of freedom required to represent the antipodally symmetric band-limited diffusion signal in the spectral (spherical harmonic) domain. Compared with existing Sampling Schemes on the sphere that allow for the accurate reconstruction of the diffusion signal, the proposed Sampling Scheme reduces the number of samples required by a factor of two or more. We analyse the numerical accuracy of the proposed SHT and show through experiments that the proposed Sampling allows for the accurate and rotationally invariant computation of the SHT to near machine precision accuracy.
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an optimal dimensionality Sampling Scheme on the sphere with fast spherical harmonic transforms
IEEE Transactions on Signal Processing, 2014Co-Authors: Zubair Khalid, Rodney A Kennedy, Jason D McewenAbstract:We develop a Sampling Scheme on the sphere that permits accurate computation of the spherical harmonic transform and its inverse for signals band-limited at L using only L 2 samples. We obtain the optimal number of samples given by the degrees of freedom of the signal in harmonic space. The number of samples required in our Scheme is a factor of two or four fewer than existing techniques, which require either 2L 2 or 4L 2 samples. We note, however, that we do not recover a Sampling theorem on the sphere, where spherical harmonic transforms are theoretically exact. Nevertheless, we achieve high accuracy even for very large band-limits. For our optimal-dimensionality Sampling Scheme, we develop a fast and accurate algorithm to compute the spherical harmonic transform (and inverse), with computational complexity comparable with existing Schemes in practice. We conduct numerical experiments to study in detail the stability, accuracy and computational complexity of the proposed transforms. We also highlight the advantages of the proposed Sampling Scheme and associated transforms in the context of potential applications.
Zubair Khalid - One of the best experts on this subject based on the ideXlab platform.
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an optimal dimensionality multi shell Sampling Scheme with accurate and efficient transforms for diffusion mri
International Symposium on Biomedical Imaging, 2017Co-Authors: Alice P Bates, Zubair Khalid, Jason D Mcewen, Rodney A KennedyAbstract:This paper proposes a multi-shell Sampling Scheme and corresponding transforms for the accurate reconstruction of the diffusion signal in diffusion MRI by expansion in the spherical polar Fourier (SPF) basis. The Sampling Scheme uses an optimal number of samples, equal to the degrees of freedom of the band-limited diffusion signal in the SPF domain, and allows for computationally efficient reconstruction. We use synthetic data sets to demonstrate that the proposed Scheme allows for greater reconstruction accuracy of the diffusion signal than the multi-shell Sampling Scheme obtained using the generalised electrostatic energy minimisation (gEEM) method used in the Human Connectome Project. We also demonstrate that the proposed Sampling Scheme allows for increased angular discrimination and improved rotational invariance of reconstruction accuracy than the gEEM Scheme.
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an optimal dimensionality Sampling Scheme on the sphere with accurate and efficient spherical harmonic transform for diffusion mri
IEEE Signal Processing Letters, 2016Co-Authors: Alice P Bates, Zubair Khalid, Rodney A KennedyAbstract:We design a Sampling Scheme on the sphere and a corresponding spherical harmonic transform (SHT) for the measurement and reconstruction of the diffusion signal in diffusion magnetic resonance imaging (dMRI). By exploiting the antipodal symmetry property of the diffusion signal in the spectral (spherical harmonic) domain, we design a Sampling Scheme that attains the optimal number of samples, equal to the degrees of freedom required to represent the antipodally symmetric band-limited diffusion signal in the spectral domain. Compared with other Sampling Schemes that can be used with the optimal number of samples, we demonstrate, through numerical experiments, that the proposed Scheme enables more accurate computation of the SHT, and this accuracy is practically rotationally invariant. In addition, it results in more efficient computation of the SHT and storage of the diffusion signal.
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novel Sampling Scheme on the sphere for head related transfer function measurements
IEEE Transactions on Audio Speech and Language Processing, 2015Co-Authors: Alice P Bates, Zubair Khalid, Rodney A KennedyAbstract:This paper presents a novel Sampling Scheme on the sphere for obtaining head-related transfer function (HRTF) measurements and accurately computing the spherical harmonic transform (SHT). The Scheme requires an optimal number of samples, given by the degrees of freedom in the spectral domain, for the accurate representation of the HRTF that is band-limited in the spherical harmonic domain. The proposed Scheme allows for the samples to be easily taken over the sphere due to its iso-latitude structure and non-dense Sampling near the poles. In addition, the Scheme can be used when samples are not taken from the south polar cap region of the sphere as the HRTF measurements are not reliable in south polar cap region due to reflections from the ground. Furthermore, the Scheme has a hierarchical structure, which enables the HRTF to be analyzed at different audible frequencies using the same Sampling configuration. In comparison to the proposed Scheme, none of the other Sampling Schemes on the sphere simultaneously possess all these properties. We conduct several numerical experiments to determine the accuracy of the SHT associated with the proposed Sampling Scheme. We show that the SHT attains accuracy on the order of numerical precision ${(10^{ - 14}})$ when samples are taken over the whole sphere, both in the optimal sample placement and hierarchical configurations, and achieves an acceptable level of accuracy ${(10^{ - 5}})$ when samples are not taken over the south polar cap region of the sphere for the band-limits of interest. Simulations are used to show the accurate reconstruction of the HRTF over the whole sphere, including unmeasured locations.
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An Optimal Dimensionality Sampling Scheme on the Sphere for Antipodal Signals In Diffusion Magnetic Resonance Imaging
arXiv: Medical Physics, 2015Co-Authors: Alice P Bates, Zubair Khalid, Rodney A KennedyAbstract:We propose a Sampling Scheme on the sphere and develop a corresponding spherical harmonic transform (SHT) for the accurate reconstruction of the diffusion signal in diffusion magnetic resonance imaging (dMRI). By exploiting the antipodal symmetry, we design a Sampling Scheme that requires the optimal number of samples on the sphere, equal to the degrees of freedom required to represent the antipodally symmetric band-limited diffusion signal in the spectral (spherical harmonic) domain. Compared with existing Sampling Schemes on the sphere that allow for the accurate reconstruction of the diffusion signal, the proposed Sampling Scheme reduces the number of samples required by a factor of two or more. We analyse the numerical accuracy of the proposed SHT and show through experiments that the proposed Sampling allows for the accurate and rotationally invariant computation of the SHT to near machine precision accuracy.
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an optimal dimensionality Sampling Scheme on the sphere with fast spherical harmonic transforms
IEEE Transactions on Signal Processing, 2014Co-Authors: Zubair Khalid, Rodney A Kennedy, Jason D McewenAbstract:We develop a Sampling Scheme on the sphere that permits accurate computation of the spherical harmonic transform and its inverse for signals band-limited at L using only L 2 samples. We obtain the optimal number of samples given by the degrees of freedom of the signal in harmonic space. The number of samples required in our Scheme is a factor of two or four fewer than existing techniques, which require either 2L 2 or 4L 2 samples. We note, however, that we do not recover a Sampling theorem on the sphere, where spherical harmonic transforms are theoretically exact. Nevertheless, we achieve high accuracy even for very large band-limits. For our optimal-dimensionality Sampling Scheme, we develop a fast and accurate algorithm to compute the spherical harmonic transform (and inverse), with computational complexity comparable with existing Schemes in practice. We conduct numerical experiments to study in detail the stability, accuracy and computational complexity of the proposed transforms. We also highlight the advantages of the proposed Sampling Scheme and associated transforms in the context of potential applications.
Alice P Bates - One of the best experts on this subject based on the ideXlab platform.
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an optimal dimensionality multi shell Sampling Scheme with accurate and efficient transforms for diffusion mri
International Symposium on Biomedical Imaging, 2017Co-Authors: Alice P Bates, Zubair Khalid, Jason D Mcewen, Rodney A KennedyAbstract:This paper proposes a multi-shell Sampling Scheme and corresponding transforms for the accurate reconstruction of the diffusion signal in diffusion MRI by expansion in the spherical polar Fourier (SPF) basis. The Sampling Scheme uses an optimal number of samples, equal to the degrees of freedom of the band-limited diffusion signal in the SPF domain, and allows for computationally efficient reconstruction. We use synthetic data sets to demonstrate that the proposed Scheme allows for greater reconstruction accuracy of the diffusion signal than the multi-shell Sampling Scheme obtained using the generalised electrostatic energy minimisation (gEEM) method used in the Human Connectome Project. We also demonstrate that the proposed Sampling Scheme allows for increased angular discrimination and improved rotational invariance of reconstruction accuracy than the gEEM Scheme.
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an optimal dimensionality Sampling Scheme on the sphere with accurate and efficient spherical harmonic transform for diffusion mri
IEEE Signal Processing Letters, 2016Co-Authors: Alice P Bates, Zubair Khalid, Rodney A KennedyAbstract:We design a Sampling Scheme on the sphere and a corresponding spherical harmonic transform (SHT) for the measurement and reconstruction of the diffusion signal in diffusion magnetic resonance imaging (dMRI). By exploiting the antipodal symmetry property of the diffusion signal in the spectral (spherical harmonic) domain, we design a Sampling Scheme that attains the optimal number of samples, equal to the degrees of freedom required to represent the antipodally symmetric band-limited diffusion signal in the spectral domain. Compared with other Sampling Schemes that can be used with the optimal number of samples, we demonstrate, through numerical experiments, that the proposed Scheme enables more accurate computation of the SHT, and this accuracy is practically rotationally invariant. In addition, it results in more efficient computation of the SHT and storage of the diffusion signal.
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novel Sampling Scheme on the sphere for head related transfer function measurements
IEEE Transactions on Audio Speech and Language Processing, 2015Co-Authors: Alice P Bates, Zubair Khalid, Rodney A KennedyAbstract:This paper presents a novel Sampling Scheme on the sphere for obtaining head-related transfer function (HRTF) measurements and accurately computing the spherical harmonic transform (SHT). The Scheme requires an optimal number of samples, given by the degrees of freedom in the spectral domain, for the accurate representation of the HRTF that is band-limited in the spherical harmonic domain. The proposed Scheme allows for the samples to be easily taken over the sphere due to its iso-latitude structure and non-dense Sampling near the poles. In addition, the Scheme can be used when samples are not taken from the south polar cap region of the sphere as the HRTF measurements are not reliable in south polar cap region due to reflections from the ground. Furthermore, the Scheme has a hierarchical structure, which enables the HRTF to be analyzed at different audible frequencies using the same Sampling configuration. In comparison to the proposed Scheme, none of the other Sampling Schemes on the sphere simultaneously possess all these properties. We conduct several numerical experiments to determine the accuracy of the SHT associated with the proposed Sampling Scheme. We show that the SHT attains accuracy on the order of numerical precision ${(10^{ - 14}})$ when samples are taken over the whole sphere, both in the optimal sample placement and hierarchical configurations, and achieves an acceptable level of accuracy ${(10^{ - 5}})$ when samples are not taken over the south polar cap region of the sphere for the band-limits of interest. Simulations are used to show the accurate reconstruction of the HRTF over the whole sphere, including unmeasured locations.
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An Optimal Dimensionality Sampling Scheme on the Sphere for Antipodal Signals In Diffusion Magnetic Resonance Imaging
arXiv: Medical Physics, 2015Co-Authors: Alice P Bates, Zubair Khalid, Rodney A KennedyAbstract:We propose a Sampling Scheme on the sphere and develop a corresponding spherical harmonic transform (SHT) for the accurate reconstruction of the diffusion signal in diffusion magnetic resonance imaging (dMRI). By exploiting the antipodal symmetry, we design a Sampling Scheme that requires the optimal number of samples on the sphere, equal to the degrees of freedom required to represent the antipodally symmetric band-limited diffusion signal in the spectral (spherical harmonic) domain. Compared with existing Sampling Schemes on the sphere that allow for the accurate reconstruction of the diffusion signal, the proposed Sampling Scheme reduces the number of samples required by a factor of two or more. We analyse the numerical accuracy of the proposed SHT and show through experiments that the proposed Sampling allows for the accurate and rotationally invariant computation of the SHT to near machine precision accuracy.
Chen Peng - One of the best experts on this subject based on the ideXlab platform.
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a higher energy efficient Sampling Scheme for networked control systems over ieee 802 15 4 wireless networks
IEEE Transactions on Industrial Informatics, 2016Co-Authors: Chen Peng, Dong Yue, Minrui FeiAbstract:This paper proposes a higher energy-efficient mixed Sampling Scheme (MSE) for networked control systems (NCSs) over IEEE 802.15.4 wireless networks. Compared with some existing periodic event-triggered Sampling (ETS) Schemes with a delayed Sampling estimation, this delay is no longer existing in MSE since there is a dynamic adjustable threshold in MSE to compensate for this delay. Compared with some existing self-triggered Sampling (STS)/ETS Schemes, MSE does not require continuous measurement of the system states and does not suffer from the conservativeness induced by a self-triggered estimation. By using the proposed MSE, one can improve the energy efficiency in energy-constrained wireless NCSs (WiNCSs) by reducing the number of transmitted packets and increasing the idle-listening period of wireless sensor nodes. An inverted pendulum (Feedback 33-005-PCI) controlled over IEEE 802.15.4 wireless networks is given to demonstrate the effectiveness of the proposed method.
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on designing a novel self triggered Sampling Scheme for networked control systems with data losses and communication delays
IEEE Transactions on Industrial Electronics, 2016Co-Authors: Chen Peng, Qing-long HanAbstract:A self-triggered Sampling Scheme (STS) is proposed for a networked control system with consideration of data losses and communication delays. By making use of this Scheme, the next Sampling instant does not depend on online estimation of an event-triggered condition and the successive measurement of the state, and can be dynamically determined with respect to the transmitted packet, the desired control performance, and the allowable number of consecutive data losses and communication delays. Consequently, the Sampling interval can be adaptively adjusted. Therefore, the communication burden can be greatly reduced and the energy efficiency can be much improved while preserving the desired ${H_\infty}$ performance. An inverted pendulum and a one-area power system controlled over a wireless sensor network are given to illustrate the effectiveness of the proposed STS.
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Self-triggered Sampling Scheme for NCSs
Communication and Control for Networked Complex Systems, 2015Co-Authors: Chen Peng, Dong Yue, Qing-long HanAbstract:In this chapter, a self-triggered Sampling Scheme for an NCS is proposed by considering network-induced delays and data dropouts simultaneously.
Marc Renaudin - One of the best experts on this subject based on the ideXlab platform.
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Adaptive Rate Filtering for a Signal Driven Sampling Scheme
2007Co-Authors: S.-m. Qaisar, Laurent Fesquet, Marc RenaudinAbstract:This work is a contribution to enhance the signal processing chain required in mobile systems. The system must be low power as it is powered by a battery. Thus a signal driven Sampling Scheme based on level crossing is employed, adapting the Sampling rate and so the system activity by following the input signal variations. In order to filter the non-uniformly sampled signal obtained at the output of this Sampling Scheme a new adaptive rate FIR filtering approach is de-vised. The idea is to combine the features of both uniform and non-uniform signal processing tools to achieve a smart online filtering process. The computational complexity of the proposed approach is deduced and compared to one of the classical FIR filtering ap-proach. It promises a significant gain of the computational effi-ciency and hence of the processing power.
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EUSIPCO - Spectral analysis of a signal driven Sampling Scheme
2006Co-Authors: S.-m. Qaisar, Laurent Fesquet, Marc RenaudinAbstract:This work is a part of a drastic revolution in the classical signal processing chain required in mobile systems. The system must be low power as it is powered by a battery. Thus a signal driven Sampling Scheme based on level crossing is adopted, delivering non-uniformly spaced out in time sampled points. In order to analyse the non-uniformly sampled signal obtained at the output of this Sampling Scheme a new spectral analysis technique is devised. The idea is to combine the features of both uniform and non-uniform signal processing chains in order to obtain a good spectrum quality with low computational complexity. The comparison of the proposed technique with General Discrete Fourier transform and Lomb's algorithm shows significant improvements in terms of spectrum quality and computational complexity.
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Spectral analysis of a signal driven Sampling Scheme
2006Co-Authors: S.-m. Qaisar, Laurent Fesquet, Marc RenaudinAbstract:This work is a part of a drastic revolution in the classical signal processing chain required in mobile systems. The system must be low power as it is powered by a battery. Thus a signal driven Sampling Scheme based on level crossing is adopted, delivering non-uniformly spaced out in time sampled points. In order to analyse the non-uniformly sampled signal obtained at the output of this Sampling Scheme a new spectral analysis technique is devised. The idea is to combine the features of both uniform and non-uniform signal processing chains in order to obtain a good spectrum quality with low computational complexity. The comparison of the proposed technique with General Discrete Fourier transform and Lomb?s algorithm shows significant improvements in terms of spectrum quality and computational complexity.
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Spectral analysis of level crossing Sampling Scheme
2005Co-Authors: F. Aeschlimann, E. Allier, Laurent Fesquet, Marc RenaudinAbstract:This paper takes place in the context of developing a new class of signal processing chains integrated on a single chip (SoC or System on Chip). The system must be low-cost, reduced-sized, low noise and especially low-power to be powered by batteries or remotely powered. Thus a new kind of Sampling Scheme called level-crossing Sampling is considered achieving non-uniformly spaced out in time sampled points. This Sampling Scheme is analyzed for periodic signal proving that the sampled signal spectrum is aliased. By weighting the spectrum, the paper shows how to improve the accuracy of the spectral analysis and prove how a Continuous Time signal can be reconstructed under conditions in spite of aliasing.
