Purpose A variety of postprocessing algorithms for CT perfusion are available, with substantial differences in terms of quantitative maps. Although potential advantages of a Bayesian estimation algorithm are suggested...
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Purpose A variety of postprocessing algorithms for CT perfusion are available, with substantial differences in terms of quantitative maps. Although potential advantages of a Bayesian estimation algorithm are suggested, direct comparison with other algorithms in clinical settings remains scarce. We aimed to compare performance of a Bayesian estimation algorithm and singularvaluedecomposition (SVD) algorithms for the assessment of acute ischemic stroke using an 80-detector row CT perfusion. Methods CT perfusion data of 36 patients with acute ischemic stroke were analyzed using the Vitrea implemented a standard SVD algorithm, a reformulated SVD algorithm and a Bayesian estimation algorithm. Correlations and statistical differences between affected and contralateral sides of quantitative parameters (cerebral blood volume [CBV], cerebral blood flow [CBF], mean transit time [MTT], time to peak [TTP] and delay) were analyzed. Agreement of the CT perfusion-estimated and the follow-up diffusion-weighted imaging-derived infarct volume were evaluated by nonparametric Passing-Bablok regression analysis. Results CBF and MTT of the Bayesian estimation algorithm were substantially different and showed a better correlation with the standard SVD algorithm (rho = 0.78 and 0.80, p < 0.001) than with the reformulated SVD algorithm (rho = 0.59 and 0.39, p < 0.001). There is no significant difference in MTT only when using the reformulated SVD algorithm (p = 0.217). Regarding the regression lines, the slope and intercept were nearly ideal with the Bayesian estimation algorithm (y = 2.42 x-6.51;rho = 0.60, p < 0.001) in comparison with the SVD algorithms. Conclusions The Bayesian estimation algorithm can lead to a better performance compared with the SVD algorithms in the assessment of acute ischemic stroke because of better delineation of abnormal perfusion areas and accurate estimation of infarct volume.
A new quantitative interpretation method of self potential anomaly related to geometric-shaped models such as horizontal cylinder, vertical cylinder, and sphere object has been proposed in this paper. This method is b...
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ISBN:
(纸本)9781479980413
A new quantitative interpretation method of self potential anomaly related to geometric-shaped models such as horizontal cylinder, vertical cylinder, and sphere object has been proposed in this paper. This method is based on the concept of solving least-squares algorithm with singularvaluedecomposition approach which is designed and implemented to calculate the depth, the electric dipole moment, the polarization angle, and the geometric shape factor of self potential anomaly. This approach uses singular value decomposition algorithm to solve non-linear inversion of self potential anomaly. The singular value decomposition algorithm was randomly tested on theoretical synthetic data which was generated by a chosen statistical distribution from a known model with different random noise level. The result shows there is a close agreement between the assumed and calculated parameters. Finally the method validity is tested on the real self potential data anomaly which is obtained from a cylindrical object that was buried at certain depth.
Objective: Design and evaluate a miniature triaxial fiber optic sensor which is integrated into the confined space at the tip of a flexible ureteroscope to measure the contact force during ureteroscopy. Methods: A not...
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Objective: Design and evaluate a miniature triaxial fiber optic sensor which is integrated into the confined space at the tip of a flexible ureteroscope to measure the contact force during ureteroscopy. Methods: A notched flexure of multilayer continuous beams is deliberately designed to modulate the sensor sensitivity to axial stiffness but not to lateral bending and torsion, and to avoid the crosstalk between axial and lateral forces. Its structure parameters are optimized by the finite element method to meet the needs of miniaturization and performance. A linear decoupled model based on the singular value decomposition algorithm is proposed to accurately compute the forces from the wavelength shifts of fiber Bragg grating. Results: Experimental results show that in the axial direction the sensor has a range of 0-4 N with a resolution of 0.014 N, and in the lateral direction it has a resolution of 0.011 N within the range of -2 N to 2 N, and is able to provide accurate measurement with an error of less than 2%. Conclusion: Primary tests show the excellent competence of the sensor to measure the interactive force at the ureteroscope tip and to discriminate objects, validating its reliability and robustness.
With the rise of industrial interconnections, deep cross-border integration between different medical industries has begun. In the context of industrial convergence, the users' medical business needs also show a t...
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With the rise of industrial interconnections, deep cross-border integration between different medical industries has begun. In the context of industrial convergence, the users' medical business needs also show a trend of diversification and personalization. The phenomenon of multi-service resource crossing and multi-organization information barriers in the traditional medical supply chain lead to a lag in the medical resource recommendation time, which makes medical enterprises face the problem of reducing the efficiency of information resource flow in industrial interconnection businesses. This study thus constructed a collaborative recommendation model of medical services based on a cloud platform by mining the characteristics of dynamic medical service resources and user demand, and used a singular value decomposition algorithm based on time context to solve the model so as to achieve reasonable recommendation of dynamic multi-service resources in the medical supply chain. The results showed that the proposed collaborative recommendation model of dynamic medical business resources based on the cloud platform can effectively achieve medical business recommendations and provide ideas for reducing the operating costs of medical enterprise alliances under the condition of industrial interconnection and improving the efficiency of industrial resource interconnection.
With the recent growth in wireless industry, and changes that occur at a faster pace in radio standards, software defined radio (SDR) provides a flexible solution when compared with hardware radios. Channelisation and...
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With the recent growth in wireless industry, and changes that occur at a faster pace in radio standards, software defined radio (SDR) provides a flexible solution when compared with hardware radios. Channelisation and sample rate conversion (SRC) are two computational intensive tasks to be carried out in SDR receivers. Reconfigurable anti-aliasing filter and channeliser with minimum reconfiguration overhead is needed for the design of SDR receivers. Low complexity, coefficientless cascaded-integrator-comb filters provides flexible reconfiguration for SRC over a wide integer range, but offers gain droop in the passband of interest. Moreover, they are not suitable for achieving SRC by fractional rates. In this study, the authors propose the design of variable digital filter (VDF) for gain droop compensation and fractional SRC to meet the spectral characteristics of multiple radio communication standards, employing singular value decomposition algorithm. The proposed design of VDF is tested for its reconfigurability with four radio standards, namely, GSM900, WCDMA/CDMA 2000 and WiMAX 802.16. Simulations carried out in MATLAB showed that the proposed VDF had improved spectral response in comparison to other methods proposed in literature.
This manuscript addresses peak-to-average ratio (PAR) reduction in orthogonal frequency division multiplexing (OFDM) based multiple-input multiple-output (MIMO) systems. A new technique for PAR reduction in point-to-p...
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ISBN:
(纸本)9781479935123
This manuscript addresses peak-to-average ratio (PAR) reduction in orthogonal frequency division multiplexing (OFDM) based multiple-input multiple-output (MIMO) systems. A new technique for PAR reduction in point-to-point scenarios is proposed. singularvaluedecomposition (SVD) algorithms usually sort the singularvalues of a MIMO channel in descending order. The last singularvalue and the associated eigenchannels of a MIMO-OFDM channel are often very weak. Not using them for data transmission will offer redundancy for PAR reduction. These eigenchannels are used to approximate the peaks which exceed a given target value in a least-squares fashion. This approximated exceedence model is then subtracted from the original signal in time domain for PAR reduction. It has been shown that a remarkable gain can be obtained with the proposed algorithm with a negligible increase in the average power and capacity loss.
This paper introduces a new description-centric algorithm for web document clustering based on Memetic algorithms with Niching Methods, Term-Document Matrix and Bayesian Information Criterion. The algorithm defines th...
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ISBN:
(纸本)9781424481262
This paper introduces a new description-centric algorithm for web document clustering based on Memetic algorithms with Niching Methods, Term-Document Matrix and Bayesian Information Criterion. The algorithm defines the number of clusters automatically. The Memetic algorithm provides a combined global and local strategy for a search in the solution space and the Niching methods to promote diversity in the population and prevent the population from converging too quickly (based on restricted competition replacement and restrictive mating). The Memetic algorithm uses the K-means algorithm to find the optimum value in a local search space. Bayesian Information Criterion is used as a fitness function, while FP-Growth is used to reduce the high dimensionality in the vocabulary. This resulting algorithm, called WDC-NMA, was tested with data sets based on Reuters-21578 and DMOZ, obtaining promising results (better precision results than a singular value decomposition algorithm). Also, it was also then initially evaluated by a group of users.
An image reconstruction algorithm based on regularization optimization for Process Tomography is proposed in this paper. Through the comparison of the images reconstructed by Linear Back Projection algorithm, Sensitiv...
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ISBN:
(纸本)9781424409723
An image reconstruction algorithm based on regularization optimization for Process Tomography is proposed in this paper. Through the comparison of the images reconstructed by Linear Back Projection algorithm, Sensitivity Coefficient algorithm, singular value decomposition algorithm and the regularization optimization algorithm proposed in this paper, it is apparent that images can be reconstructed clearly and quickly by the regularization optimization algorithm. The regularization optimization algorithm is a very good image reconstruction algorithm both in image quality and the reconstruction speed.
An image reconstruction algorithm based on regularization optimization for Process Tomography is proposed in this *** the comparison of the images reconstructed by Linear Back Projection algorithm, Sensitivity Coeffic...
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An image reconstruction algorithm based on regularization optimization for Process Tomography is proposed in this *** the comparison of the images reconstructed by Linear Back Projection algorithm, Sensitivity Coefficient algorithm, singular value decomposition algorithm and the regularization optimization algorithm proposed in this paper, it is apparent that images can be reconstructed clearly and quickly by the regularization optimization *** regularization optimization algorithm is a very good image reconstruction algorithm both in image quality and the reconstruction speed.
Almost four decades passed after the discovery of solitons and infinite dimensional integrable systems. The theory of integrable systems has had great impact to wide area in physics and mathematics. In this paper an a...
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ISBN:
(纸本)0769521509
Almost four decades passed after the discovery of solitons and infinite dimensional integrable systems. The theory of integrable systems has had great impact to wide area in physics and mathematics. In this paper an approach to numerical algorithms in terms of integrable systems is surveyed. Some integrable systems of Lax form describe continuous flows of efficient numerical algorithms, for example, the QR algorithm and the Jacobi algorithm. Discretizations of integrable systems in tau-function level enable us to formulate algorithms for computing continued fractions such as the qd algorithm and the discrete Schur flow. A new singularvaluedecomposition (I-SVD) algorithm is designed by using a discrete integrable system defined by the Christoffel-Darboux identity for orthogonal polynomials.
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