A CLASS OF NONMONOTONE CONJUGATE GRADIENT METHODS FOR NONCONVEX FUNCTIONS
Institute of Scientific and Technical Information of China (English)
LiuYun; WeiZengxin
2002-01-01
This paper discusses the global convergence of a class of nonmonotone conjugate gradient methods (NM methods) for nonconvex object functions. This class of methods includes the nonmonotone counterpart of modified Polak-Ribiere method and modified Hestenes-Stiefel method as special cases.
Adaptive nonmonotone line search method for unconstrained optimization
Institute of Scientific and Technical Information of China (English)
Qunyan ZHOU; Wenyu SUN
2008-01-01
In this paper, an adaptive nonmonotone line search method for unconstrained minimization problems is proposed. At every iteration, the new algorithm selects only one of the two directions: a Newton-type direc-tion and a negative curvature direction, to perform the line search. The nonmonotone technique is included in the backtracking line search when the Newton-type direction is the search direction. Furthermore, if the negative curvature direction is the search direction, we increase the steplength un-der certain conditions. The global convergence to a stationary point with second-order optimality conditions is established. Some numerical results which show the efficiency of the new algorithm are reported.
The global convergence of the non-quasi-Newton methods with non-monotone line search
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
The non-quasi-Newton methods for unconstrained optimization was investigated. Non-monotone line search procedure is introduced, which is combined with the non-quasi-Newton family. Under the uniform convexity assumption on objective function, the global convergence of the non-quasi-Newton family was proved.Numerical experiments showed that the non-monotone line search was more effective.
AN ADAPTIVE NONMONOTONIC TRUST REGION METHOD WITH CURVILINEAR SEARCHES
Institute of Scientific and Technical Information of China (English)
Qun-yan Zhou; Wen-yu Sun
2006-01-01
In this paper, an algorithm for unconstrained optimization that employs both trust region techniques and curvilinear searches is proposed. At every iteration, we solve the trust region subproblem whose radius is generated adaptively only once. Nonmonotonic backtracking curvilinear searches are performed when the solution of the subproblem is unacceptable. The global convergence and fast local convergence rate of the proposed algorithms are established under some reasonable conditions. The results of numerical experiments are reported to show the effectiveness of the proposed algorithms.
An unconstrained optimization method using nonmonotone second order Goldstein's line search
Institute of Scientific and Technical Information of China (English)
Wen-yu; SUN; Qun-yan; ZHOU
2007-01-01
In this paper, an unconstrained optimization method using the nonmonotone second order Goldstein's line search is proposed. By using the negative curvature information from the Hessian,the sequence generated is shown to converge to a stationary point with the second order optimality conditions. Numerical tests on a set of standard test problems confirm the efficiency of our new method.
VARIED STEPLENGTH NONMONOTONE PATTERN SEARCH METHOD%变步长非单调模式搜索法
Institute of Scientific and Technical Information of China (English)
杨春; 倪勤
2005-01-01
A varied steplength nonmonotone pattern search method is proposed in this paper. The varied steplength search strategy is designed in this method such that the pattern direction is more approximated to efficient descent direction. The interpolation and nonmonotone technique are used for improving local search and global convergence. The theoretical and numerical results show that this method is an efficient direct search method.
Global Convergence of the Broyden's Class of Quasi-Newton Methods with Nonmonotone Linesearch
Institute of Scientific and Technical Information of China (English)
Da-chuan Xu
2003-01-01
In this paper, the Broyden class of quasi-Newton methods for unconstrained optimization is investigated. Non-monotone linesearch procedure is introduced, which is combined with the Broyden's class. Under the convexity assumption on objective function, the global convergence of the Broyden's class is proved.
Nonmonotone Spectral Gradient Method for l_1-regularized Least Squares
Directory of Open Access Journals (Sweden)
Wanyou Cheng
2016-08-01
Full Text Available In the paper, we investigate a linear constraint optimization reformulation to a more general form of the l_1 regularization problem and give some good properties of it. We first show that the equivalence between the linear constraint optimization problem and the l_1 regularization problem. Second, the KKT point of the linear constraint problem always exists since the constraints are linear; we show that the half constraints must be active at any KKT point. In addition, we show that the KKT points of the linear constraint problem are the same as the stationary points of the l_1 regularization problem. Based on the linear constraint optimization problem, we propose a nonomotone spectral gradient method and establish its global convergence. Numerical experiments with compressive sense problems show that our approach is competitive with several known methods for standard l_2-l_1 problem.
Institute of Scientific and Technical Information of China (English)
De-tong Zhu
2001-01-01
In this paper we modify type approximate trust region methods via two curvilinear paths for unconstrained optimization. A mixed strategy using both trust region and line search techniques is adopted which switches to back tracking steps when a trial step produced by the trust region subproblem is unacceptable. We give a series of properties of both optimal path and modified gradient path. The global convergence and fast local convergence rate of the proposed algorithms are established under some reasonable conditions. A nonmonotonic criterion is used to speed up the convergence progress in some ill-conditioned cases.
Institute of Scientific and Technical Information of China (English)
Sun Qingying
2005-01-01
In this paper, a new class of three term memory gradient method with nonmonotone line search technique for unconstrained optimization is presented. Global convergence properties of the new methods are discussed. Combining the quasi-Newton method with the new method, the former is modified to have global convergence property. Numerical results show that the new algorithm is efficient.
Institute of Scientific and Technical Information of China (English)
Peihua GUO; Detong ZHU
2008-01-01
The authors propose an affine scaling modified gradient path method in association with reduced projective Hessian and nonmonotonic interior backtracking line search techniques for solving the linear equality constrained optimization subject to bounds on variables. By employing the QR decomposition of the constraint matrix and the eigensystem decomposition of reduced projective Hes-sian matrix in the subproblem, the authors form affine scaling modified gradient curvilinear path very easily. By using interior backtracking line search technique, each iterate switches to trial step of strict interior feasibility. The global convergence and fast local superlinear/quadratical convergence rates of the proposed algorithm are established under some reasonable conditions. A nonmonotonic criterion should bring about speeding up the convergence progress in some ill-conditioned cases. The results of numerical experiments are reported to show the effectiveness of the proposed algorithm.
Institute of Scientific and Technical Information of China (English)
ZHU Detong
2000-01-01
This paper proposes projected gradient algorithms in association with using both trust region and line search techniques for convex constrained optimization problems.The mixed strategy is adopted which switches to back tracking steps when a trial projected gradient step produced by the trust region subproblem is unacceptable. A nonmonotone criterion is used to speed up the convergence progress in some curves with large curvature.A theoretical analysis is given which proves that the proposed algorithms are globally convergent and have local superlinear convergence rate under some reasonable conditions.The results of numerical experiments are reported to show the effectiveness of the proposed algorithms.
Institute of Scientific and Technical Information of China (English)
林作铨
1996-01-01
A modal nonmonotonic logic is presented based on an experiential modal semantics on typicality and exception.The syntactic and semantics of modal nonmonotonic logic are provided,and the completeness theorem and the theorems relating it to major nonmonotonic logics are proved.It directly formalizes the intuition of nonmonotonic reasoning.Among other things,it provides us a first-order extension of default logic and autoepistemic logic,and simultaneously has the capability of circumscription to infer universal statement.It has important applications in logic programming and deductive data base.As a result,it provides a uniform basis for various nonmonotonic logics,from which the correspondent relationship among major nonmonotonic logics can coincide.
Method of securing filter elements
Energy Technology Data Exchange (ETDEWEB)
Brown, Erik P.; Haslam, Jeffery L.; Mitchell, Mark A.
2016-10-04
A filter securing system including a filter unit body housing; at least one tubular filter element positioned in the filter unit body housing, the tubular filter element having a closed top and an open bottom; a dimple in either the filter unit body housing or the top of the tubular filter element; and a socket in either the filter unit body housing or the top of the tubular filter element that receives the dimple in either the filter unit body housing or the top of the tubular filter element to secure the tubular filter element to the filter unit body housing.
DEMONSTRATION BULLETIN: COLLOID POLISHING FILTER METHOD - FILTER FLOW TECHNOLOGY, INC.
The Filter Flow Technology, Inc. (FFT) Colloid Polishing Filter Method (CPFM) was tested as a transportable, trailer mounted, system that uses sorption and chemical complexing phenomena to remove heavy metals and nontritium radionuclides from water. Contaminated waters can be pro...
Zhao, Xueyan; Deng, Feiqi
2016-07-01
In this paper, a particular property of Lyapunov functions for functional differential equations (FDEs) is developed, that is the direct dependence of the signs of the derivatives of the Lyapunov functions on the initial data. This property implies that the derivatives of the Lyapunov functions for FDEs cannot be guaranteed to be negative definite generally, and then makes the FDEs differ from the ordinary differential equations constitutionally. With this property, we give some enlightenments for the research methods for establishing stability theorems or criteria for FDEs, which may help us to form a common view about the choice of the investigation methods on the stability of FDEs. The conclusion is stated in both the deterministic and stochastic versions. Two illustrative examples are given to show and verify our conclusion through the paper.
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
Based on a differentiable merit function proposed by Taji,et al in "Mathematical Programming,1993,58: 369-383",a projected gradient trust region method for the monotone variational inequality problem with convex constraints is presented.Theoretical analysis is given which proves that the proposed algorithm is globally convergent and has a local quadratic convergence rate under some reasonable conditions.The results of numerical experiments are reported to show the effectiveness of the proposed algorithm.
An Adaptive Iterated Nonlocal Interferometry Filtering Method
Directory of Open Access Journals (Sweden)
Lin Xue
2014-04-01
Full Text Available Interferometry filtering is one of the key steps in obtain high-precision Digital Elevation Model (DEM and Digital Orthophoto Map (DOM. In the case of low-correlation or complicated topography, traditional phase filtering methods fail in balancing noise elimination and phase preservation, which leads to inaccurate interferometric phase. This paper proposed an adaptive iterated nonlocal interferometry filtering method to deal with the problem. Based on the thought of nonlocal filtering, the proposed method filters the image with utilization of the image redundancy information. The smoothing parameter of the method is adaptive to the interferometry, and automatic iteration, in which the window size is adjusted, is applied to improve the filtering precision. Validity of the proposed method is verified by simulated and real data. Comparison with existed methods is given at the same time.
Neural method of spatiotemporal filter design
Szostakowski, Jaroslaw
1997-10-01
There is a lot of applications in medical imaging, computer vision, and the communications, where the video processing is critical. Although many techniques have been successfully developed for the filtering of the still-images, significantly fewer techniques have been proposed for the filtering of noisy image sequences. In this paper the novel approach to spatio- temporal filtering design is proposed. The multilayer perceptrons and functional-link nets are used for the 3D filtering. The spatio-temporal patterns are creating from real motion video images. The neural networks learn these patterns. The perceptrons with different number of layers and neurons in each layer are tested. Also, the different input functions in functional- link net are searched. The practical examples of the filtering are shown and compared with traditional (non-neural) spatio-temporal methods. The results are very interesting and the neural spatio-temporal filters seems to be very efficient tool for video noise reduction.
Filters, reproducing kernel, and adaptive meshfree method
You, Y.; Chen, J.-S.; Lu, H.
Reproducing kernel, with its intrinsic feature of moving averaging, can be utilized as a low-pass filter with scale decomposition capability. The discrete convolution of two nth order reproducing kernels with arbitrary support size in each kernel results in a filtered reproducing kernel function that has the same reproducing order. This property is utilized to separate the numerical solution into an unfiltered lower order portion and a filtered higher order portion. As such, the corresponding high-pass filter of this reproducing kernel filter can be used to identify the locations of high gradient, and consequently serves as an operator for error indication in meshfree analysis. In conjunction with the naturally conforming property of the reproducing kernel approximation, a meshfree adaptivity method is also proposed.
Q-Method Extended Kalman Filter
Zanetti, Renato; Ainscough, Thomas; Christian, John; Spanos, Pol D.
2012-01-01
A new algorithm is proposed that smoothly integrates non-linear estimation of the attitude quaternion using Davenport s q-method and estimation of non-attitude states through an extended Kalman filter. The new method is compared to a similar existing algorithm showing its similarities and differences. The validity of the proposed approach is confirmed through numerical simulations.
Zhang, Hong
2016-01-01
An adaptive moving mesh finite difference method is presented to solve two types of equations with dynamic capillary pressure term in porous media. One is the non-equilibrium Richards Equation and the other is the modified Buckley-Leverett equation. The governing equations are discretized with an adaptive moving mesh finite difference method in the space direction and an implicit-explicit method in the time direction. In order to obtain high quality meshes, an adaptive time-dependent monitor function with directional control is applied to redistribute the mesh grid in every time step, and a diffusive mechanism is used to smooth the monitor function. The behaviors of the central difference flux, the standard local Lax-Friedrich flux and the local Lax-Friedrich flux with reconstruction are investigated by solving a 1D modified Buckley-Leverett equation. With the moving mesh technique, good mesh quality and high numerical accuracy are obtained. A collection of one-dimensional and two-dimensional numerical experi...
Restricted Kalman Filtering Theory, Methods, and Application
Pizzinga, Adrian
2012-01-01
In statistics, the Kalman filter is a mathematical method whose purpose is to use a series of measurements observed over time, containing random variations and other inaccuracies, and produce estimates that tend to be closer to the true unknown values than those that would be based on a single measurement alone. This Brief offers developments on Kalman filtering subject to general linear constraints. There are essentially three types of contributions: new proofs for results already established; new results within the subject; and applications in investment analysis and macroeconomics, where th
Filtered cathodic arc deposition apparatus and method
Krauss, Alan R.
1999-01-01
A filtered cathodic arc deposition method and apparatus for the production of highly dense, wear resistant coatings which are free from macro particles. The filtered cathodic arc deposition apparatus includes a cross shaped vacuum chamber which houses a cathode target having an evaporable surface comprised of the coating material, means for generating a stream of plasma, means for generating a transverse magnetic field, and a macro particle deflector. The transverse magnetic field bends the generated stream of plasma in the direction of a substrate. Macro particles are effectively filtered from the stream of plasma by traveling, unaffected by the transverse magnetic field, along the initial path of the plasma stream to a macro particle deflector. The macro particle deflector has a preformed surface which deflects macro particles away from the substrate.
Method and apparatus for a self-cleaning filter
Diebold, James P.; Lilley, Arthur; Browne, III, Kingsbury; Walt, Robb Ray; Duncan, Dustin; Walker, Michael; Steele, John; Fields, Michael
2010-11-16
A method and apparatus for removing fine particulate matter from a fluid stream without interrupting the overall process or flow. The flowing fluid inflates and expands the flexible filter, and particulate is deposited on the filter media while clean fluid is permitted to pass through the filter. This filter is cleaned when the fluid flow is stopped, the filter collapses, and a force is applied to distort the flexible filter media to dislodge the built-up filter cake. The dislodged filter cake falls to a location that allows undisrupted flow of the fluid after flow is restored. The shed particulate is removed to a bin for periodic collection. A plurality of filter cells can operate independently or in concert, in parallel, or in series to permit cleaning the filters without shutting off the overall fluid flow. The self-cleaning filter is low cost, has low power consumption, and exhibits low differential pressures.
Nonmonotonic diffusion in crowded environments
Putzel, Gregory Garbès; Tagliazucchi, Mario; Szleifer, Igal
2015-01-01
We study the diffusive motion of particles among fixed spherical crowders. The diffusers interact with the crowders through a combination of a hard-core repulsion and a short-range attraction. The long-time effective diffusion coefficient of the diffusers is found to depend non-monotonically on the strength of their attraction to the crowders. That is, for a given concentration of crowders, a weak attraction to the crowders enhances diffusion. We show that this counterintuitive fact can be understood in terms of the mesoscopic excess chemical potential landscape experienced by the diffuser. The roughness of this excess chemical potential landscape quantitatively captures the nonmonotonic dependence of the diffusion rate on the strength of crowder-diffuser attraction; thus it is a purely static predictor of dynamic behavior. The mesoscopic view given here provides a unified explanation for enhanced diffusion effects that have been found in various systems of technological and biological interest. PMID:25302920
A NONMONOTONE TRUST REGION ALGORITHM FOR NONLINEAR OPTIMIZATION SUBJECT TO GENERAL CONSTRAINTS
Institute of Scientific and Technical Information of China (English)
Hongchao Zhang
2003-01-01
In this paper we present a nonmonotone trust region algorithm for general nonlinear constrained optimization problems. The main idea of this paper is to combine Yuan's technique[1] with a nonmonotone method similar to Ke and Han [2]. This new algorithm may not only keep the robust properties of the algorithm given by Yuan, but also have some advantages led by the nonmonotone technique. Under very mild conditions, global convergence for the algorithm is given. Numerical experiments demonstrate the efficiency of the algorithm.
A NONMONOTONE CONJUGATE GRADIENT ALGORITHM FOR UNCONSTRAINED OPTIMIZATION
Institute of Scientific and Technical Information of China (English)
DAI Yuhong
2002-01-01
Conjugate gradient methods are very important methods for unconstrained optimization, especially for large scale problems. In this paper, we propose a new conjugate gradient method, in which the technique of nonmonotone line search is used. Under mild assumptions, we prove the global convergence of the method. Some numerical results are also presented.
A multiscale method to calculate filter blockage
Dalwadi, Mohit P; Griffiths, Ian M
2016-01-01
Filters that act by adsorbing contaminant onto their pore walls will experience a decrease in porosity over time, and may eventually block. As adsorption will generally be larger towards the entrance of a filter, where the concentration of contaminant particles is higher, these effects can also result in a spatially varying porosity. We investigate this dynamic process using an extension of homogenization theory that accounts for a macroscale variation in microstructure. We formulate and homogenize the coupled problems of flow through a filter with a near-periodic time-dependent microstructure, solute transport due to advection, diffusion, and filter adsorption, and filter structure evolution due to the adsorption of contaminant. We use the homogenized equations to investigate how the contaminant removal and filter lifespan depend on the initial porosity distribution for a unidirectional flow. We confirm a conjecture made in Dalwadi et al. (2015) that filters with an initially negative porosity gradient have ...
Research on adaptive filtering method for electrostatic signals
Xu, Hongke; Pang, Yue; Yi, Yingmin
2017-05-01
The signal will be inevitably mixed with various types of noise in the process of transmission, which causes the distortion of information in different degree, in order to obtain accurate information, it's an important work to suppress random noise in the digital signal processing system. This paper mainly studies the adaptive filtering method, using LMS algorithm in adaptive filter (Least mean square LMS algorithm), when the filter starts reading the electrostatic signal, it also can estimate the statistical characteristics of electrostatic signal, adaptive adjust its filter parameters, filtering the electrostatic signal on time, attain the maximum noise suppression, to avoid distortion of information, and to achieve optimal filtering.
Layered neural networks with non-monotonic transfer functions
Katayama, Katsuki; Sakata, Yasuo; Horiguchi, Tsuyoshi
2003-01-01
We investigate storage capacity and generalization ability for two types of fully connected layered neural networks with non-monotonic transfer functions; random patterns are embedded into the networks by a Hebbian learning rule. One of them is a layered network in which a non-monotonic transfer function of even layers is different from that of odd layers. The other is a layered network with intra-layer connections, in which the non-monotonic transfer function of inter-layer is different from that of intra-layer, and inter-layered neurons and intra-layered neurons are updated alternately. We derive recursion relations for order parameters for those layered networks by the signal-to-noise ratio method. We clarify that the storage capacity and the generalization ability for those layered networks are enhanced in comparison with those with a conventional monotonic transfer function when non-monotonicity of the transfer functions is selected optimally. We also point out that some chaotic behavior appears in the order parameters for the layered networks when non-monotonicity of the transfer functions increases.
Directory of Open Access Journals (Sweden)
INTAN S. AHMAD
2008-04-01
Full Text Available This work presents the application of a primal-dual interior point method to minimax optimisation problems. The algorithm differs significantly from previous approaches as it involves a novel non-monotone line search procedure, which is based on the use of standard penalty methods as the merit function used for line search. The crucial novel concept is the discretisation of the penalty parameter used over a finite range of orders of magnitude and the provision of a memory list for each such order. An implementation within a logarithmic barrier algorithm for bounds handling is presented with capabilities for large scale application. Case studies presented demonstrate the capabilities of the proposed methodology, which relies on the reformulation of minimax models into standard nonlinear optimisation models. Some previously reported case studies from the open literature have been solved, and with significantly better optimal solutions identified. We believe that the nature of the non-monotone line search scheme allows the search procedure to escape from local minima, hence the encouraging results obtained.
A hybrid method for optimization of the adaptive Goldstein filter
Jiang, Mi; Ding, Xiaoli; Tian, Xin; Malhotra, Rakesh; Kong, Weixue
2014-12-01
The Goldstein filter is a well-known filter for interferometric filtering in the frequency domain. The main parameter of this filter, alpha, is set as a power of the filtering function. Depending on it, considered areas are strongly or weakly filtered. Several variants have been developed to adaptively determine alpha using different indicators such as the coherence, and phase standard deviation. The common objective of these methods is to prevent areas with low noise from being over filtered while simultaneously allowing stronger filtering over areas with high noise. However, the estimators of these indicators are biased in the real world and the optimal model to accurately determine the functional relationship between the indicators and alpha is also not clear. As a result, the filter always under- or over-filters and is rarely correct. The study presented in this paper aims to achieve accurate alpha estimation by correcting the biased estimator using homogeneous pixel selection and bootstrapping algorithms, and by developing an optimal nonlinear model to determine alpha. In addition, an iteration is also merged into the filtering procedure to suppress the high noise over incoherent areas. The experimental results from synthetic and real data show that the new filter works well under a variety of conditions and offers better and more reliable performance when compared to existing approaches.
SITE TECHNOLOGY CAPSULE: FILTER FLOW TECHNOLOGY, INC. - COLLOID POLISHING FILTER METHOD
The Filter Flow Technology, Inc. (FFT) Coloid Polishing Filter Method (CPFM) was demonstrated at the U.S Department of Energy's (DOE) Rock Flats Plant (RFP) as part of the U.S. Environmental Protection Agency's (EPA) Superfund and Innovative Technology Evaluation (SITE) program. ...
A multilateral filtering method applied to airplane runway image
Yu, Zhang; Run-quan, Wang
2008-01-01
By considering the features of the airport runway image filtering, an improved bilateral filtering method was proposed which can remove noise with edge preserving. Firstly the steerable filtering decomposition is used to calculate the sub-band parameters of 4 orients, and the texture feature matrix is then obtained from the sub-band local median energy. The texture similar, the spatial closer and the color similar functions are used to filter the image.The effect of the weighting function parameters is qualitatively analyzed also. In contrast with the standard bilateral filter and the simulation results for the real airport runway image show that the multilateral filtering is more effective than the standard bilateral filtering.
Multispectral image filtering method based on image fusion
Zhang, Wei; Chen, Wei
2015-12-01
This paper proposed a novel filter scheme by image fusion based on Nonsubsampled ContourletTransform(NSCT) for multispectral image. Firstly, an adaptive median filter is proposed which shows great advantage in speed and weak edge preserving. Secondly, the algorithm put bilateral filter and adaptive median filter on image respectively and gets two denoised images. Then perform NSCT multi-scale decomposition on the de-noised images and get detail sub-band and approximate sub-band. Thirdly, the detail sub-band and approximate sub-band are fused respectively. Finally, the object image is obtained by inverse NSCT. Simulation results show that the method has strong adaptability to deal with the textural images. And it can suppress noise effectively and preserve the image details. This algorithm has better filter performance than the Bilateral filter standard and median filter and theirs improved algorithms for different noise ratio.
Aspects and modular reasoning in nonmonotonic logic
DEFF Research Database (Denmark)
Ostermann, Klaus
2008-01-01
Nonmonotonic logic is a branch of logic that has been developed to model situations with incomplete information. We argue that there is a connection between AOP and nonmonotonic logic which deserves further study. As a concrete technical contribution and "appetizer", we outline an AO semantics de...... defined in default logic (a form of nonmonotonic logic), propose a definition of modular reasoning, and show that the default logic version of the language semantics admits modular reasoning whereas a conventional language semantics based on weaving does not....
An improved filtered spherical harmonic method for transport calculations
Energy Technology Data Exchange (ETDEWEB)
Ahrens, C. [Department of Applied Mathematics and Statistics, Colorado School of Mines, Golden, CO 80401 (United States); Merton, S. [Computational Physics Group, AWE Aldermaston, Berkshire (United Kingdom)
2013-07-01
Motivated by the work of R. G. McClarren, C. D. Hauck, and R. B. Lowrie on a filtered spherical harmonic method, we present a new filter for such numerical approximations to the multi-dimensional transport equation. In several test problems, we demonstrate that the new filter produces results with significantly less Gibbs phenomena than the filter used by McClarren, Hauck and Lowrie. This reduction in Gibbs phenomena translates into propagation speeds that more closely match the correct propagation speed and solutions that have fewer regions where the scalar flux is negative. (authors)
The Günther-Tulip retrievable filter: a method for assessing tilting of the filter.
Semiz-Oysu, Aslihan; Cho, Kyung J
2010-04-01
Tilting of the Günther-Tulip filter may be responsible for failure or difficulty to retrieve. Assessment of the filter tilt can be difficult when only AP imaging is available. This study is performed in vitro to develop a simple method to assess the Günther-Tulip filter for tilting. A model consisting of a plastic tube was used to simulate vena cava. A Günther-Tulip filter was placed centred or tilted within the tube at various positions and radiograms were taken in AP, lateral, and craniocaudally angled projections. The images were analysed to determine the actual degree of tilt, the distance between the limb hooks on AP radiograms and the craniocaudal angulation degree needed to align the limb hooks linearly. When the filter was centred or tilted laterally, all limb hooks of the filter were aligned linearly on AP radiograms. When the filter was tilted in AP or oblique direction, linear alignment of the limb hooks was lost and the ventral and dorsal limb hooks showed separation on AP projection. The amount of separation and the craniocaudal angles to align the filter hooks corresponded to actual tilt angles. Loss of linear alignment of limb hooks in AP radiograms may suggest the presence of tilt in the AP plane. Significant separation of limb hooks should be alarming for significant filter tilt, and further evaluation of the filter position by CT scan or lateral cavogram should be obtained prior to planning of the retrieval. Copyright 2009 Australasian Society of Cardiac and Thoracic Surgeons and the Cardiac Society of Australia and New Zealand. Published by Elsevier B.V. All rights reserved.
Directory of Open Access Journals (Sweden)
Cahit Tağı ÇELİK
2004-01-01
Full Text Available Monitoring the Crustal Movement in Geodesy is performed by the deformation survey and analysis. If monitoring the crustal movements involves more than two epochs of survey campaign then from the plate tectonic theory, stations do not move randomly from one epoch to the other, therefore Kalman Filter may be suitable to use. However, if sudden movements happened in the crust in particular earthquake happened, the crust moves very fast in a very short period of time. When Kalman Filter used for monitoring these movements, from associated epoch, for a number of epochs the results may be biased. In the paper, comparison of two methods for elimination of the above mentioned biases have been performed. These methods are Fading Memory Filter and Adaptive Kalman Filter for an unknown bias.
On filter-successive linearization methods for nonlinear semidefinite programming
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
In this paper we present a filter-successive linearization method with trust region for solutions of nonlinear semidefinite programming. Such a method is based on the concept of filter for nonlinear programming introduced by Fletcher and Leyffer in 2002. We describe the new algorithm and prove its global convergence under weaker assumptions. Some numerical results are reported and show that the new method is potentially effcient.
On filter-successive linearization methods for nonlinear semidefinite programming
Institute of Scientific and Technical Information of China (English)
LI ChengJin; SUN WenYui
2009-01-01
In this paper we present a filter-successive linearization method with trust region for solutions of nonlinear semidefinite programming. Such a method is based on the concept of filter for nonlinear programming introduced by Fletcher and Leyffer in 2002. We describe the new algorithm and prove its global convergence under weaker assumptions. Some numerical results are reported and show that the new method is potentially efficient.
Motion estimation using point cluster method and Kalman filter.
Senesh, M; Wolf, A
2009-05-01
The most frequently used method in a three dimensional human gait analysis involves placing markers on the skin of the analyzed segment. This introduces a significant artifact, which strongly influences the bone position and orientation and joint kinematic estimates. In this study, we tested and evaluated the effect of adding a Kalman filter procedure to the previously reported point cluster technique (PCT) in the estimation of a rigid body motion. We demonstrated the procedures by motion analysis of a compound planar pendulum from indirect opto-electronic measurements of markers attached to an elastic appendage that is restrained to slide along the rigid body long axis. The elastic frequency is close to the pendulum frequency, as in the biomechanical problem, where the soft tissue frequency content is similar to the actual movement of the bones. Comparison of the real pendulum angle to that obtained by several estimation procedures--PCT, Kalman filter followed by PCT, and low pass filter followed by PCT--enables evaluation of the accuracy of the procedures. When comparing the maximal amplitude, no effect was noted by adding the Kalman filter; however, a closer look at the signal revealed that the estimated angle based only on the PCT method was very noisy with fluctuation, while the estimated angle based on the Kalman filter followed by the PCT was a smooth signal. It was also noted that the instantaneous frequencies obtained from the estimated angle based on the PCT method is more dispersed than those obtained from the estimated angle based on Kalman filter followed by the PCT method. Addition of a Kalman filter to the PCT method in the estimation procedure of rigid body motion results in a smoother signal that better represents the real motion, with less signal distortion than when using a digital low pass filter. Furthermore, it can be concluded that adding a Kalman filter to the PCT procedure substantially reduces the dispersion of the maximal and minimal
Novel design method for generalized lattice filters
DEFF Research Database (Denmark)
Agger, Søren; Povlsen, Jørn Hedegaard; Leick, Lasse;
2003-01-01
A new design method for wide-band gain equalizers using cascaded MZI's is proposed. The method achieves a given accuracy with fewer stages than previously described methods. Furthermore, the method is capable of minimizing PDL.......A new design method for wide-band gain equalizers using cascaded MZI's is proposed. The method achieves a given accuracy with fewer stages than previously described methods. Furthermore, the method is capable of minimizing PDL....
A Filter Method for Nonlinear Semidefinite Programming with Global Convergence
Institute of Scientific and Technical Information of China (English)
Zhi Bin ZHU; Hua Li ZHU
2014-01-01
In this study, a new filter algorithm is presented for solving the nonlinear semidefinite programming. This algorithm is inspired by the classical sequential quadratic programming method. Unlike the traditional filter methods, the suffi cient descent is ensured by changing the step size instead of the trust region radius. Under some suitable conditions, the global convergence is obtained. In the end, some numerical experiments are given to show that the algorithm is eff ective.
A Mathematical Model for Non-monotonic Deposition Profiles in Deep Bed Filtration Systems
DEFF Research Database (Denmark)
Yuan, Hao; Shapiro, Alexander
2011-01-01
A mathematical model for suspension/colloid flow in porous media and non-monotonic deposition is proposed. It accounts for the migration of particles associated with the pore walls via the second energy minimum (surface associated phase). The surface associated phase migration is characterized...... by advection and diffusion/dispersion. The proposed model is able to produce a nonmonotonic deposition profile. A set of methods for estimating the modeling parameters is provided in the case of minimal particle release. The estimation can be easily performed with available experimental information...... condition for producing non-monotonic deposition profiles. The described physics by the additional equation may be different in different experimental settings....
Multivariate localization methods for ensemble Kalman filtering
Roh, S.
2015-05-08
In ensemble Kalman filtering (EnKF), the small number of ensemble members that is feasible to use in a practical data assimilation application leads to sampling variability of the estimates of the background error covariances. The standard approach to reducing the effects of this sampling variability, which has also been found to be highly efficient in improving the performance of EnKF, is the localization of the estimates of the covariances. One family of localization techniques is based on taking the Schur (entry-wise) product of the ensemble-based sample covariance matrix and a correlation matrix whose entries are obtained by the discretization of a distance-dependent correlation function. While the proper definition of the localization function for a single state variable has been extensively investigated, a rigorous definition of the localization function for multiple state variables has been seldom considered. This paper introduces two strategies for the construction of localization functions for multiple state variables. The proposed localization functions are tested by assimilating simulated observations experiments into the bivariate Lorenz 95 model with their help.
Multivariate localization methods for ensemble Kalman filtering
Roh, S.
2015-12-03
In ensemble Kalman filtering (EnKF), the small number of ensemble members that is feasible to use in a practical data assimilation application leads to sampling variability of the estimates of the background error covariances. The standard approach to reducing the effects of this sampling variability, which has also been found to be highly efficient in improving the performance of EnKF, is the localization of the estimates of the covariances. One family of localization techniques is based on taking the Schur (element-wise) product of the ensemble-based sample covariance matrix and a correlation matrix whose entries are obtained by the discretization of a distance-dependent correlation function. While the proper definition of the localization function for a single state variable has been extensively investigated, a rigorous definition of the localization function for multiple state variables that exist at the same locations has been seldom considered. This paper introduces two strategies for the construction of localization functions for multiple state variables. The proposed localization functions are tested by assimilating simulated observations experiments into the bivariate Lorenz 95 model with their help.
Multivariate localization methods for ensemble Kalman filtering
Directory of Open Access Journals (Sweden)
S. Roh
2015-05-01
Full Text Available In ensemble Kalman filtering (EnKF, the small number of ensemble members that is feasible to use in a practical data assimilation application leads to sampling variability of the estimates of the background error covariances. The standard approach to reducing the effects of this sampling variability, which has also been found to be highly efficient in improving the performance of EnKF, is the localization of the estimates of the covariances. One family of localization techniques is based on taking the Schur (entry-wise product of the ensemble-based sample covariance matrix and a correlation matrix whose entries are obtained by the discretization of a distance-dependent correlation function. While the proper definition of the localization function for a single state variable has been extensively investigated, a rigorous definition of the localization function for multiple state variables has been seldom considered. This paper introduces two strategies for the construction of localization functions for multiple state variables. The proposed localization functions are tested by assimilating simulated observations experiments into the bivariate Lorenz 95 model with their help.
Multivariate localization methods for ensemble Kalman filtering
Roh, S.; Jun, M.; Szunyogh, I.; Genton, M. G.
2015-12-01
In ensemble Kalman filtering (EnKF), the small number of ensemble members that is feasible to use in a practical data assimilation application leads to sampling variability of the estimates of the background error covariances. The standard approach to reducing the effects of this sampling variability, which has also been found to be highly efficient in improving the performance of EnKF, is the localization of the estimates of the covariances. One family of localization techniques is based on taking the Schur (element-wise) product of the ensemble-based sample covariance matrix and a correlation matrix whose entries are obtained by the discretization of a distance-dependent correlation function. While the proper definition of the localization function for a single state variable has been extensively investigated, a rigorous definition of the localization function for multiple state variables that exist at the same locations has been seldom considered. This paper introduces two strategies for the construction of localization functions for multiple state variables. The proposed localization functions are tested by assimilating simulated observations experiments into the bivariate Lorenz 95 model with their help.
Evaluation of harmonic detection methods for active power filter applications
DEFF Research Database (Denmark)
Asiminoaei, Lucian; Blaabjerg, Frede; Hansen, Steffan
2005-01-01
filter is to use a good method for current/voltage reference generation. There exist many implementations supported by different theories (either in time- or frequency-domain), which continuously debate their performances proposing ever better solutions. This paper gives a survey of the common used...... theories. Then, the work here proposes a simulation setup that decouples the harmonic reference generator from the active filter model and its controller. In this way the selected methods can be equally analyzed and compared with respect to their performance, which helps anticipating possible...... implementation issues. The conclusions are collected and a comparison is given at the end, which is useful in deciding the future hardware setup implementation. The comparison shows that the choice of numerical filtering is a key factor for obtaining good accuracies and dynamics for an active filter....
A quantitative sampling method for Oncomelania quadrasi by filter paper.
Tanaka, H; Santos, M J; Matsuda, H; Yasuraoka, K; Santos, A T
1975-08-01
Filter paper was found to attract Oncomelania quadrasi in waters the same way as fallen dried banana leaves, although less number of other species of snails was collected on the former than on the latter. Snails were collected in limited areas using a tube (85 cm2 area at cross-section) and a filter paper (20 X 20 CM) samplers. The sheet of filter paper was placed close to the spot where a tube sample was taken, and recovered after 24 hours. At each sampling, 30 samples were taken by each method in an area and sampling was made four times. The correlation of the number of snails collected by the tube and that by filter paper was studied. The ratio of the snail counts by the tube sampler to those by the filter paper was 1.18. A loose correlation was observed between snail counts of both methods as shown by the correlation coefficient r = 0.6502. The formulas for the regression line were Y = 0.77 X + 1.6 and X = 0.55 Y + 1.35 for 3 experiments where Y is the number of snails collected by tube sampling and X is the number of snails collected in the sheet of filter paper. The type of snail distribution was studied in the 30 samples taken by each method and this was observed to be nearly the same in both sampling methods. All sampling data were found to fit the negative binomial distribution with the values of the constant k varying very much from 0.5775 to 5.9186 in (q -- p)-k. In each experiment, the constant k was always larger in tube sampling than in filter paper sampling. This indicates that the uneven distribution of snails on the soil surface becomes more conspicuous by the filter paper sampling.
Adaptive Subband Filtering Method for MEMS Accelerometer Noise Reduction
Directory of Open Access Journals (Sweden)
Piotr PIETRZAK
2008-12-01
Full Text Available Silicon microaccelerometers can be considered as an alternative to high-priced piezoelectric sensors. Unfortunately, relatively high noise floor of commercially available MEMS (Micro-Electro-Mechanical Systems sensors limits the possibility of their usage in condition monitoring systems of rotating machines. The solution of this problem is the method of signal filtering described in the paper. It is based on adaptive subband filtering employing Adaptive Line Enhancer. For filter weights adaptation, two novel algorithms have been developed. They are based on the NLMS algorithm. Both of them significantly simplify its software and hardware implementation and accelerate the adaptation process. The paper also presents the software (Matlab and hardware (FPGA implementation of the proposed noise filter. In addition, the results of the performed tests are reported. They confirm high efficiency of the solution.
Subpixel edge detection method based on low-frequency filtering
Bylinsky, Yosip Y.; Kotyra, Andrzej; Gromaszek, Konrad; Iskakova, Aigul
2016-09-01
A method of edge detection in images is proposed basing that based on low-frequency filtering. The method uses polynomial interpolation to determine the coordinates of the edge point with subpixel accuracy. Some experiments have been results also have been provided.
A modified iterative ensemble Kalman filter data assimilation method
Xu, Baoxiong; Bai, Yulong; Wang, Yizhao; Li, Zhe; Ma, Boyang
2017-08-01
High nonlinearity is a typical characteristic associated with data assimilation systems. Additionally, iterative ensemble based methods have attracted a large amount of research attention, which has been focused on dealing with nonlinearity problems. To solve the local convergence problem of the iterative ensemble Kalman filter, a modified iterative ensemble Kalman filter algorithm was put forward, which was based on a global convergence strategy from the perspective of a Gauss-Newton iteration. Through self-adaption, the step factor was adjusted to enable every iteration to approach expected values during the process of the data assimilation. A sensitivity experiment was carried out in a low dimensional Lorenz-63 chaotic system, as well as a Lorenz-96 model. The new method was tested via ensemble size, observation variance, and inflation factor changes, along with other aspects. Meanwhile, comparative research was conducted with both a traditional ensemble Kalman filter and an iterative ensemble Kalman filter. The results showed that the modified iterative ensemble Kalman filter algorithm was a data assimilation method that was able to effectively estimate a strongly nonlinear system state.
A comparison of methods for DPLL loop filter design
Aguirre, S.; Hurd, W. J.; Kumar, R.; Statman, J.
1986-01-01
Four design methodologies for loop filters for a class of digital phase-locked loops (DPLLs) are presented. The first design maps an optimum analog filter into the digital domain; the second approach designs a filter that minimizes in discrete time weighted combination of the variance of the phase error due to noise and the sum square of the deterministic phase error component; the third method uses Kalman filter estimation theory to design a filter composed of a least squares fading memory estimator and a predictor. The last design relies on classical theory, including rules for the design of compensators. Linear analysis is used throughout the article to compare different designs, and includes stability, steady state performance and transient behavior of the loops. Design methodology is not critical when the loop update rate can be made high relative to loop bandwidth, as the performance approaches that of continuous time. For low update rates, however, the miminization method is significantly superior to the other methods.
Directory of Open Access Journals (Sweden)
Marija Kaevska
2015-09-01
Full Text Available Introduction and objective. Mycobacteria have been isolated from almost all types of natural waters, as well as from man-made water distribution systems. Detection of mycobacteria using PCR has been described in different types of water; however, currently, there is no standardised protocol for the processing of large volumes of water. Material and Methods. In the present study, different filtering methods are tested and optimised for tap or river water filtration up to 10 L, as well as filter processing and DNA isolation using four commercially available kits. Results. The PowerWater DNA isolation kit (MoBio, USA, together with a kit used for soil and other environmental samples (PowerSoil DNA isolation kit, MoBio, had the highest efficiency. Filtration of 10 L of water and elution of the filter in PBS with the addition of 0.05% of Tween 80 is suggested. Conclusions. The described protocol for filter elution is recommended, and the use of the PowerWater DNA isolation kit for the highest mycobacterial DNA yield from water samples. The described protocol is suitable for parallel detection of mycobacteria using cultivation.
Causation, explanation and nonmonotonic temporal reasoning
Grünwald, P.D.
1997-01-01
We introduce a new approach to reasoning about action and change using nonmonotonic logic. The approach is arrived at by applying Pearl's theory of causal networks to logical formalizations of temporal reasoning domains. It handles complicated reasoning domains involving concurrent actions, actions
Stabilizing the thermal lattice Boltzmann method by spatial filtering.
Gillissen, J J J
2016-10-01
We propose to stabilize the thermal lattice Boltzmann method by filtering the second- and third-order moments of the collision operator. By means of the Chapman-Enskog expansion, we show that the additional numerical diffusivity diminishes in the low-wavnumber limit. To demonstrate the enhanced stability, we consider a three-dimensional thermal lattice Boltzmann system involving 33 discrete velocities. Filtering extends the linear stability of this thermal lattice Boltzmann method to 10-fold smaller transport coefficients. We further demonstrate that the filtering does not compromise the accuracy of the hydrodynamics by comparing simulation results to reference solutions for a number of standardized test cases, including natural convection in two dimensions.
Simplified Method for Groundwater Treatment Using Dilution and Ceramic Filter
Musa, S.; Ariff, N. A.; Kadir, M. N. Abdul; Denan, F.
2016-07-01
Groundwater is one of the natural resources that is not susceptible to pollutants. However, increasing activities of municipal, industrial, agricultural or extreme land use activities have resulted in groundwater contamination as occured at the Research Centre for Soft Soil Malaysia (RECESS), Universiti Tun Hussein Onn Malaysia (UTHM). Thus, aims of this study is to treat groundwater by using rainwater and simple ceramic filter as a treatment agent. The treatment uses rain water dilution, ceramic filters and combined method of dilute and filtering as an alternate treatment which are simple and more practical compared to modern or chemical methods. The water went through dilution treatment processes able to get rid of 57% reduction compared to initial condition. Meanwhile, the water that passes through the filtering process successfully get rid of as much as 86% groundwater parameters where only chloride does not pass the standard. Favorable results for the combination methods of dilution and filtration methods that can succesfully eliminate 100% parameters that donot pass the standards of the Ministry of Health and the Interim National Drinking Water Quality Standard such as those found in groundwater in RECESS, UTHM especially sulfate and chloride. As a result, it allows the raw water that will use clean drinking water and safe. It also proves that the method used in this study is very effective in improving the quality of groundwater.
Kaevska, Marija; Slana, Iva
2015-01-01
Mycobacteria have been isolated from almost all types of natural waters, as well as from man-made water distribution systems. Detection of mycobacteria using PCR has been described in different types of water; however, currently, there is no standardised protocol for the processing of large volumes of water. In the present study, different filtering methods are tested and optimised for tap or river water filtration up to 10 L, as well as filter processing and DNA isolation using four commercially available kits. The PowerWater DNA isolation kit (MoBio, USA), together with a kit used for soil and other environmental samples (PowerSoil DNA isolation kit, MoBio), had the highest efficiency. Filtration of 10 L of water and elution of the filter in PBS with the addition of 0.05% of Tween 80 is suggested. The described protocol for filter elution is recommended, and the use of the PowerWater DNA isolation kit for the highest mycobacterial DNA yield from water samples. The described protocol is suitable for parallel detection of mycobacteria using cultivation.
Evaluation of five decontamination methods for filtering facepiece respirators.
Viscusi, Dennis J; Bergman, Michael S; Eimer, Benjamin C; Shaffer, Ronald E
2009-11-01
Concerns have been raised regarding the availability of National Institute for Occupational Safety and Health (NIOSH)-certified N95 filtering facepiece respirators (FFRs) during an influenza pandemic. One possible strategy to mitigate a respirator shortage is to reuse FFRs following a biological decontamination process to render infectious material on the FFR inactive. However, little data exist on the effects of decontamination methods on respirator integrity and performance. This study evaluated five decontamination methods [ultraviolet germicidal irradiation (UVGI), ethylene oxide, vaporized hydrogen peroxide (VHP), microwave oven irradiation, and bleach] using nine models of NIOSH-certified respirators (three models each of N95 FFRs, surgical N95 respirators, and P100 FFRs) to determine which methods should be considered for future research studies. Following treatment by each decontamination method, the FFRs were evaluated for changes in physical appearance, odor, and laboratory performance (filter aerosol penetration and filter airflow resistance). Additional experiments (dry heat laboratory oven exposures, off-gassing, and FFR hydrophobicity) were subsequently conducted to better understand material properties and possible health risks to the respirator user following decontamination. However, this study did not assess the efficiency of the decontamination methods to inactivate viable microorganisms. Microwave oven irradiation melted samples from two FFR models. The remainder of the FFR samples that had been decontaminated had expected levels of filter aerosol penetration and filter airflow resistance. The scent of bleach remained noticeable following overnight drying and low levels of chlorine gas were found to off-gas from bleach-decontaminated FFRs when rehydrated with deionized water. UVGI, ethylene oxide (EtO), and VHP were found to be the most promising decontamination methods; however, concerns remain about the throughput capabilities for EtO and VHP
An analytical filter design method for guided wave phased arrays
Kwon, Hyu-Sang; Kim, Jin-Yeon
2016-12-01
This paper presents an analytical method for designing a spatial filter that processes the data from an array of two-dimensional guided wave transducers. An inverse problem is defined where the spatial filter coefficients are determined in such a way that a prescribed beam shape, i.e., a desired array output is best approximated in the least-squares sense. Taking advantage of the 2π-periodicity of the generated wave field, Fourier-series representation is used to derive closed-form expressions for the constituting matrix elements. Special cases in which the desired array output is an ideal delta function and a gate function are considered in a more explicit way. Numerical simulations are performed to examine the performance of the filters designed by the proposed method. It is shown that the proposed filters can significantly improve the beam quality in general. Most notable is that the proposed method does not compromise between the main lobe width and the sidelobe levels; i.e. a narrow main lobe and low sidelobes are simultaneously achieved. It is also shown that the proposed filter can compensate the effects of nonuniform directivity and sensitivity of array elements by explicitly taking these into account in the formulation. From an example of detecting two separate targets, how much the angular resolution can be improved as compared to the conventional delay-and-sum filter is quantitatively illustrated. Lamb wave based imaging of localized defects in an elastic plate using a circular array is also presented as an example of practical applications.
Path Renewal Method in Filtering Based Wireless Sensor Networks
Directory of Open Access Journals (Sweden)
Tae Ho Cho
2011-01-01
Full Text Available In applications of wireless sensor networks, there are many security issues. Attackers can create false reports and transmit the reports to the networks. These false reports can lead not only false alarms, but also the depletion of limited energy resources. In order to filter out such false reports during the forwarding process, Ye et al. proposed the statistical en-route filtering (SEF. Several research efforts to enhance the efficiency of SEF have been made. Especially, the path selection method proposed by Sun et al. can improve the detection power of SEF by considering the information on the filtering keys of and distances of upstream paths. However, such selection mechanism could lead to favored paths in heavy traffic, which would result in unbalanced energy consumption. In this paper, we propose a path renewal method to provide load balancing for sensor networks in terms of energy consumption. In our method, a node renews its upstream path to save energy resources if the remaining energy of and the communication traffic of the node exceed some threshold values. We show the effectiveness of the proposed method in terms of balanced energy consumption and filtering power by providing simulation results.
Ranking filter methods for concentrating pathogens in lake water
Accurately comparing filtration methods for concentrating waterborne pathogens is difficult because of two important water matrix effects on recovery measurements, the effect on PCR quantification and the effect on filter performance. Regarding the first effect, we show how to create a control water...
Rapid separation method for actinides in emergency air filter samples.
Maxwell, Sherrod L; Culligan, Brian K; Noyes, Gary W
2010-12-01
A new rapid method for the determination of actinides and strontium in air filter samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used in emergency response situations. The actinides and strontium in air filter method utilizes a rapid acid digestion method and a streamlined column separation process with stacked TEVA, TRU and Sr Resin cartridges. Vacuum box technology and rapid flow rates are used to reduce analytical time. Alpha emitters are prepared using cerium fluoride microprecipitation for counting by alpha spectrometry. The purified (90)Sr fractions are mounted directly on planchets and counted by gas flow proportional counting. The method showed high chemical recoveries and effective removal of interferences. This new procedure was applied to emergency air filter samples received in the NRIP Emergency Response exercise administered by the National Institute for Standards and Technology (NIST) in April, 2009. The actinide and (90)Sr in air filter results were reported in less than 4 h with excellent quality. Copyright 2010 Elsevier Ltd. All rights reserved.
A new method for adaptive color image filtering
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
An adaptive color image filter (ACIF) is proposed in this note. Through analyzing noise corruption of color image, efficient locally adaptive filters are chosen for image enhancement. The proposed adaptive color image filter combines advantages of both nonlinear vector filters and linear filters, it attenuates noise and preserves edges and details very well. Experimental results show that the proposed filter performs better than vector median filter, directional-distance filter, directional-magnitude vector filter, adaptive nearest-neighbor filter, and -trimmed mean filter.
Nonmonotonic Skeptical Consequence Relation in Constrained Default Logic
Directory of Open Access Journals (Sweden)
Mihaiela Lupea
2010-12-01
Full Text Available This paper presents a study of the nonmonotonic consequence relation which models the skeptical reasoning formalised by constrained default logic. The nonmonotonic skeptical consequence relation is defined using the sequent calculus axiomatic system. We study the formal properties desirable for a good nonmonotonic relation: supraclassicality, cut, cautious monotony, cumulativity, absorption, distribution.
An Applied Method for Designing Maximally Decimating Non-uniform Filter Banks
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
Assembling individual line phase filters to form a multi-channel filter bank allows the synthesis filter to be similar to corresponding analysis filters, and the design calculation can be simple. The appropriate relations between synthesis filters and analysis filters eliminate most aliasing resulting from decimation in non-uniform maximally decimating filter banks, and LS algorithm and Remez algorithm are used to optimize the composite character. This design method can achieve approximate Perfect-Reconstruction. An example is given in which the general parameter filters with approximate line phase are used as units of a filter bank.
Complexity of Non-Monotonic Logics
Thomas, Michael
2010-01-01
Over the past few decades, non-monotonic reasoning has developed to be one of the most important topics in computational logic and artificial intelligence. Different ways to introduce non-monotonic aspects to classical logic have been considered, e.g., extension with default rules, extension with modal belief operators, or modification of the semantics. In this survey we consider a logical formalism from each of the above possibilities, namely Reiter's default logic, Moore's autoepistemic logic and McCarthy's circumscription. Additionally, we consider abduction, where one is not interested in inferences from a given knowledge base but in computing possible explanations for an observation with respect to a given knowledge base. Complexity results for different reasoning tasks for propositional variants of these logics have been studied already in the nineties. In recent years, however, a renewed interest in complexity issues can be observed. One current focal approach is to consider parameterized problems and ...
Optimizing Fungal DNA Extraction Methods from Aerosol Filters
Jimenez, G.; Mescioglu, E.; Paytan, A.
2016-12-01
Fungi and fungal spores can be picked up from terrestrial ecosystems, transported long distances, and deposited into marine ecosystems. It is important to study dust-borne fungal communities, because they can stay viable and effect the ambient microbial populations, which are key players in biogeochemical cycles. One of the challenges of studying dust-borne fungal populations is that aerosol samples contain low biomass, making extracting good quality DNA very difficult. The aim of this project was to increase DNA yield by optimizing DNA extraction methods. We tested aerosol samples collected from Haifa, Israel (polycarbonate filter), Monterey Bay, CA (quartz filter) and Bermuda (quartz filter). Using the Qiagen DNeasy Plant Kit, we tested the effect of altering bead beating times and incubation times, adding three freeze and thaw steps, initially washing the filters with buffers for various lengths of time before using the kit, and adding a step with 30 minutes of sonication in 65C water. Adding three freeze/thaw steps, adding a sonication step, washing with a phosphate buffered saline overnight, and increasing incubation time to two hours, in that order, resulted in the highest increase in DNA for samples from Israel (polycarbonate). DNA yield of samples from Monterey (quart filter) increased about 5 times when washing with buffers overnight (phosphate buffered saline and potassium phophate buffer), adding a sonication step, and adding three freeze and thaw steps. Samples collected in Bermuda (quartz filter) had the highest increase in DNA yield from increasing incubation to 2 hours, increasing bead beating time to 6 minutes, and washing with buffers overnight (phosphate buffered saline and potassium phophate buffer). Our results show that DNA yield can be increased by altering various steps of the Qiagen DNeasy Plant Kit protocol, but different types of filters collected at different sites respond differently to alterations. These results can be used as
NONMONOTONE PRECONDITIONAL CURVILINEAR PATH ALGORITHMS FOR UNCONSTRAINED OPTIMIZATION
Institute of Scientific and Technical Information of China (English)
朱德通
2003-01-01
This paper presents nonmonotonic quasi-Newton algorithms via two pre-conditional curvilinear paths, the preconditional modified gradient path and the precon-ditional optimal path, for unconstrained optimization problem. We employ the stableBunch-Parlett factorization method to form two curvilinear paths very easily. Thenonmonotone criterion is used to speed up the convergence progress in the contoursof objective function with large curvature. Theoretical analyses are given which provethat the proposed algorithms are globally convergent and have a local superlinear con-vergence rate under some reasonable conditions. The results of numerical experimentsare reported to show the effectiveness of the proposed algorithms.
Evaluation of Five Decontamination Methods for Filtering Facepiece Respirators
Viscusi, Dennis J.; Bergman, Michael S.; Eimer, Benjamin C.; Ronald E. Shaffer
2009-01-01
Concerns have been raised regarding the availability of National Institute for Occupational Safety and Health (NIOSH)-certified N95 filtering facepiece respirators (FFRs) during an influenza pandemic. One possible strategy to mitigate a respirator shortage is to reuse FFRs following a biological decontamination process to render infectious material on the FFR inactive. However, little data exist on the effects of decontamination methods on respirator integrity and performance. This study eval...
Tunnel Point Cloud Filtering Method Based on Elliptic Cylindrical Model
Zhua, Ningning; Jiaa, Yonghong; Luo, Lun
2016-06-01
The large number of bolts and screws that attached to the subway shield ring plates, along with the great amount of accessories of metal stents and electrical equipments mounted on the tunnel walls, make the laser point cloud data include lots of non-tunnel section points (hereinafter referred to as non-points), therefore affecting the accuracy for modeling and deformation monitoring. This paper proposed a filtering method for the point cloud based on the elliptic cylindrical model. The original laser point cloud data was firstly projected onto a horizontal plane, and a searching algorithm was given to extract the edging points of both sides, which were used further to fit the tunnel central axis. Along the axis the point cloud was segmented regionally, and then fitted as smooth elliptic cylindrical surface by means of iteration. This processing enabled the automatic filtering of those inner wall non-points. Experiments of two groups showed coincident results, that the elliptic cylindrical model based method could effectively filter out the non-points, and meet the accuracy requirements for subway deformation monitoring. The method provides a new mode for the periodic monitoring of tunnel sections all-around deformation in subways routine operation and maintenance.
TUNNEL POINT CLOUD FILTERING METHOD BASED ON ELLIPTIC CYLINDRICAL MODEL
Directory of Open Access Journals (Sweden)
N. Zhu
2016-06-01
Full Text Available The large number of bolts and screws that attached to the subway shield ring plates, along with the great amount of accessories of metal stents and electrical equipments mounted on the tunnel walls, make the laser point cloud data include lots of non-tunnel section points (hereinafter referred to as non-points, therefore affecting the accuracy for modeling and deformation monitoring. This paper proposed a filtering method for the point cloud based on the elliptic cylindrical model. The original laser point cloud data was firstly projected onto a horizontal plane, and a searching algorithm was given to extract the edging points of both sides, which were used further to fit the tunnel central axis. Along the axis the point cloud was segmented regionally, and then fitted as smooth elliptic cylindrical surface by means of iteration. This processing enabled the automatic filtering of those inner wall non-points. Experiments of two groups showed coincident results, that the elliptic cylindrical model based method could effectively filter out the non-points, and meet the accuracy requirements for subway deformation monitoring. The method provides a new mode for the periodic monitoring of tunnel sections all-around deformation in subways routine operation and maintenance.
A filtering method for the interval eigenvalue problem
DEFF Research Database (Denmark)
Hladik, Milan; Daney, David; Tsigaridas, Elias
2011-01-01
We consider the general problem of computing intervals that contain the real eigenvalues of interval matrices. Given an outer approximation (superset) of the real eigenvalue set of an interval matrix, we propose a filtering method that iteratively improves the approximation. Even though our method...... is based on a sufficient regularity condition, it is very efficient in practice and our experimental results suggest that it improves, in general, significantly the initial outer approximation. The proposed method works for general, as well as for symmetric interval matrices....
Tang, Chen; Zhang, Fang; Yan, Haiqing; Chen, Zhanqing
2006-04-01
Denoising in electronic speckle pattern interferometry fringes is the key problem in electronic speckle pattern interferometry. We present the new filtering method based on partial differential equations (called PDE filtering method) to electronic speckle pattern interferometry fringes. The PDE filtering method transforms the image processing to solving the partial differential equations. We test the proposed method on experimentally obtained electronic speckle pattern interferometry fringes, and compare with traditional mean filtering and low-pass Fourier filtering methods. The experimental results show that the technique is capable of effectively removing noise. The PDE filtering method is flexible and has fast computational speed and stable results.
Taboada-Serrano, Patricia; Tsouris, Constantino; Contescu, Cristian I; McFarlane, Joanna
2013-10-08
The present invention provides magnetically responsive activated carbon, and a method of forming magnetically responsive activated carbon. The method of forming magnetically responsive activated carbon typically includes providing activated carbon in a solution containing ions of ferrite forming elements, wherein at least one of the ferrite forming elements has an oxidation state of +3 and at least a second of the ferrite forming elements has an oxidation state of +2, and increasing pH of the solution to precipitate particles of ferrite that bond to the activated carbon, wherein the activated carbon having the ferrite particles bonded thereto have a positive magnetic susceptibility. The present invention also provides a method of filtering waste water using magnetic activated carbon.
Fuzzy Filtering Method for Color Videos Corrupted by Additive Noise
Directory of Open Access Journals (Sweden)
Volodymyr I. Ponomaryov
2014-01-01
Full Text Available A novel method for the denoising of color videos corrupted by additive noise is presented in this paper. The proposed technique consists of three principal filtering steps: spatial, spatiotemporal, and spatial postprocessing. In contrast to other state-of-the-art algorithms, during the first spatial step, the eight gradient values in different directions for pixels located in the vicinity of a central pixel as well as the R, G, and B channel correlation between the analogous pixels in different color bands are taken into account. These gradient values give the information about the level of contamination then the designed fuzzy rules are used to preserve the image features (textures, edges, sharpness, chromatic properties, etc.. In the second step, two neighboring video frames are processed together. Possible local motions between neighboring frames are estimated using block matching procedure in eight directions to perform interframe filtering. In the final step, the edges and smoothed regions in a current frame are distinguished for final postprocessing filtering. Numerous simulation results confirm that this novel 3D fuzzy method performs better than other state-of-the-art techniques in terms of objective criteria (PSNR, MAE, NCD, and SSIM as well as subjective perception via the human vision system in the different color videos.
A consensus rating method for small virus-retentive filters. I. Method development.
Lute, Scott; Riordan, William; Pease, Leonard F; Tsai, De-Hao; Levy, Richard; Haque, Mohammed; Martin, Jerold; Moroe, Ichiro; Sato, Terry; Morgan, Michael; Krishnan, Mani; Campbell, Jennifer; Genest, Paul; Dolan, Sherri; Tarrach, Klaus; Meyer, Anika; Zachariah, Michael R; Tarlov, Michael J; EtzeL, Mark; Brorson, Kurt; Aranha, Hazel; Bailey, Mark; Bender, Jean; Carter, Jeff; Chen, Qi; Dowd, Chris; Jani, Raj; Jen, David; Kidd, Stanley; Meltzer, Ted; Remington, Kathryn; Rice, Iris; Romero, Cynthia; Sato, Terry; Jornitz, Maik; Sekura, Carol Marcus; Sofer, Gail; Specht, Rachel; Wojciechowski, Peter
2008-01-01
Virus filters are membrane-based devices that remove large viruses (e.g., retroviruses) and/or small viruses (e.g., parvoviruses) from products by a size exclusion mechanism. In 2002, the Parenteral Drug Association (PDA) organized the PDA Virus Filter Task Force to develop a common nomenclature and a standardized test method for classifying and identifying viral-retentive filters. One goal of the task force was to develop a test method for small virus-retentive filters. Because small virus-retentive filters present unique technical challenges, the test method development process was guided by laboratory studies to determine critical variables such as choice of bacteriophage challenge, choice of model protein, filtration operating parameters, target log10 reduction value, and filtration endpoint definition. Based on filtration, DLS, electrospray differential mobility analysis, and polymerase chain reaction studies, a final rating based on retention of bacteriophage PP7 was chosen by the PDA Virus Filter Task Force. The detailed final consensus filter method was published in the 2008 update of PDA Technical Report 41. Virus Filtration.
An algebraic method for constructing stable and consistent autoregressive filters
Energy Technology Data Exchange (ETDEWEB)
Harlim, John, E-mail: jharlim@psu.edu [Department of Mathematics, the Pennsylvania State University, University Park, PA 16802 (United States); Department of Meteorology, the Pennsylvania State University, University Park, PA 16802 (United States); Hong, Hoon, E-mail: hong@ncsu.edu [Department of Mathematics, North Carolina State University, Raleigh, NC 27695 (United States); Robbins, Jacob L., E-mail: jlrobbi3@ncsu.edu [Department of Mathematics, North Carolina State University, Raleigh, NC 27695 (United States)
2015-02-15
In this paper, we introduce an algebraic method to construct stable and consistent univariate autoregressive (AR) models of low order for filtering and predicting nonlinear turbulent signals with memory depth. By stable, we refer to the classical stability condition for the AR model. By consistent, we refer to the classical consistency constraints of Adams–Bashforth methods of order-two. One attractive feature of this algebraic method is that the model parameters can be obtained without directly knowing any training data set as opposed to many standard, regression-based parameterization methods. It takes only long-time average statistics as inputs. The proposed method provides a discretization time step interval which guarantees the existence of stable and consistent AR model and simultaneously produces the parameters for the AR models. In our numerical examples with two chaotic time series with different characteristics of decaying time scales, we find that the proposed AR models produce significantly more accurate short-term predictive skill and comparable filtering skill relative to the linear regression-based AR models. These encouraging results are robust across wide ranges of discretization times, observation times, and observation noise variances. Finally, we also find that the proposed model produces an improved short-time prediction relative to the linear regression-based AR-models in forecasting a data set that characterizes the variability of the Madden–Julian Oscillation, a dominant tropical atmospheric wave pattern.
Wet Refractivity Tomography with an hnproved Kalman-Filter Method
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
An improved retrieval method, which uses the solution with a Gaussian constraint as the initial state variables for the Kalman Filtering (KF) method, was developed to retrieve the wet refractivity profiles from slant wet delays (SWD) extracted by the double-differenced (DD) GPS method. The accuracy of the GPS-derived SWDs is also tested in this study against the measurements of a water vapor radiometer (WVR) and a weather model. It is concluded that the GPS-derived SWDs have similar accuracy to those measured with WVR and are much higher in quality than those derived from the weather model used. The developed method is used to retrieve the 3D wet refractivity distribution in the Hong Kong region. The retrieved profiles agree well with the radiosonde observations, with a difference of about 4 mm km-1 in the low levels. The accurate profiles obtained with this method are applicable in a number of meteorological applications.
Adaptive Current Control Method for Hybrid Active Power Filter
Chau, Minh Thuyen
2016-09-01
This paper proposes an adaptive current control method for Hybrid Active Power Filter (HAPF). It consists of a fuzzy-neural controller, identification and prediction model and cost function. The fuzzy-neural controller parameters are adjusted according to the cost function minimum criteria. For this reason, the proposed control method has a capability on-line control clings to variation of the load harmonic currents. Compared to the single fuzzy logic control method, the proposed control method shows the advantages of better dynamic response, compensation error in steady-state is smaller, able to online control is better and harmonics cancelling is more effective. Simulation and experimental results have demonstrated the effectiveness of the proposed control method.
Methods of filtering the graph images of the functions
Directory of Open Access Journals (Sweden)
Олександр Григорович Бурса
2017-06-01
Full Text Available The theoretical aspects of cleaning raster images of scanned graphs of functions from digital, chromatic and luminance distortions by using computer graphics techniques have been considered. The basic types of distortions characteristic of graph images of functions have been stated. To suppress the distortion several methods, providing for high-quality of the resulting images and saving their topological features, were suggested. The paper describes the techniques developed and improved by the authors: the method of cleaning the image of distortions by means of iterative contrasting, based on the step-by-step increase in image contrast in the graph by 1%; the method of small entities distortion restoring, based on the thinning of the known matrix of contrast increase filter (the allowable dimensions of the nucleus dilution radius convolution matrix, which provide for the retention of the graph lines have been established; integration technique of the noise reduction method by means of contrasting and distortion restoring method of small entities with known σ-filter. Each method in the complex has been theoretically substantiated. The developed methods involve treatment of graph images as the entire image (global processing and its fragments (local processing. The metrics assessing the quality of the resulting image with the global and local processing have been chosen, the substantiation of the choice as well as the formulas have been given. The proposed complex methods of cleaning the graphs images of functions from grayscale image distortions is adaptive to the form of an image carrier, the distortion level in the image and its distribution. The presented results of testing the developed complex of methods for a representative sample of images confirm its effectiveness
Directory of Open Access Journals (Sweden)
Cătălin LUPU
2014-12-01
Full Text Available This article presents the development of optimal filters through covolution methods, necessary for restoring, correcting and improving fingerprints acquired from a sensor, able to provide the most ideal image in the output. After the image was binarized and equalized, Canny filter is applied in order to: eliminate the noise (filtering the image with a Gaussian filter, non-maxima suppression, module gradient adaptive binarization and extension edge points edges by hysteresis. The resulting image after applying Canny filter is not ideal. It is possible that the result will be an image with very fragmented edges and many pores in ridge. For the resulting image, a bank of convolution filters are applied one after another (Kirsch, Laplace, Roberts, Prewitt, Sobel, Frei-Chen, averaging convolution filter, circular convolution filter, lapacian convolution filter, gaussian convolution filter, LoG convolution filter, DoG, inverted filters, Wiener, the filter of ”equalization of the power spectrum” (intermediary filter between the Wiener filter and the inverted filter, the geometrical average filter , etc. with different features.
Sequential Monte Carlo methods for nonlinear discrete-time filtering
Bruno, Marcelo GS
2013-01-01
In these notes, we introduce particle filtering as a recursive importance sampling method that approximates the minimum-mean-square-error (MMSE) estimate of a sequence of hidden state vectors in scenarios where the joint probability distribution of the states and the observations is non-Gaussian and, therefore, closed-form analytical expressions for the MMSE estimate are generally unavailable.We begin the notes with a review of Bayesian approaches to static (i.e., time-invariant) parameter estimation. In the sequel, we describe the solution to the problem of sequential state estimation in line
A consensus rating method for small virus-retentive filters. II. Method evaluation.
Brorson, Kurt; Lute, Scott; Haque, Mohammed; Martin, Jerold; Sato, Terry; Moroe, Ichiro; Morgan, Michael; Krishnan, Mani; Campbell, Jennifer; Genest, Paul; Parrella, Joseph; Dolan, Sherri; Martin, Susan; Tarrach, Klaus; Levy, Richard; Aranha, Hazel; Bailey, Mark; Bender, Jean; Carter, Jeff; Chen, Qi; Dowd, Chris; Jani, Raj; Jen, David; Kidd, Stanley; Meltzer, Ted; Remington, Kathryn; Rice, Iris; Romero, Cynthia; Sato, Terry; Jornitz, Maik; Sekura, Carol Marcus; Sofer, Gail; Specht, Rachel; Wojciechowski, Peter
2008-01-01
Virus filters are membrane-based devices that remove large viruses (e.g., retroviruses) and/or small viruses (e.g., parvoviruses) from products by a size exclusion mechanism. In 2002, the Parenteral Drug Association (PDA) organized the PDA Virus Filter Task Force to develop a common nomenclature and a standardized test method for classifying and identifying viral-retentive filters. A test method based on bacteriophage PP7 retention was chosen based on developmental studies. The detailed final consensus filter method is published in the 2008 update of PDA Technical Report 41: Virus Filtration. Here, we evaluate the method and find it to be acceptable for testing scaled-down models of small virus-retentive filters from four manufacturers. Three consecutive lots of five filter types were tested (Pegasus SV4, Viresolve NFP, Planova 20N and 15N, Virosart CPV). Each passed the criteria specified in the test method (i.e., >4 log10 PP7 retention, >90% intravenous immunoglobulin passage, and passing integrity/installation testing) and was classified as PP7-LRV4.
Institute of Scientific and Technical Information of China (English)
Hong Xia YIN; Dong Lei DU
2007-01-01
The self-scaling quasi-Newton method solves an unconstrained optimization problem by scaling the Hessian approximation matrix before it is updated at each iteration to avoid the possible large eigenvalues in the Hessian approximation matrices of the objective function. It has been proved in the literature that this method has the global and superlinear convergence when the objective function is convex (or even uniformly convex). We propose to solve unconstrained nonconvex optimization problems by a self-scaling BFGS algorithm with nonmonotone linear search. Nonmonotone line search has been recognized in numerical practices as a competitive approach for solving large-scale nonlinear problems. We consider two different nonmonotone line search forms and study the global convergence of these nonmonotone self-scale BFGS algorithms. We prove that, under some weaker condition than that in the literature, both forms of the self-scaling BFGS algorithm are globally convergent for unconstrained nonconvex optimization problems.
Computation of non-monotonic Lyapunov functions for continuous-time systems
Li, Huijuan; Liu, AnPing
2017-09-01
In this paper, we propose two methods to compute non-monotonic Lyapunov functions for continuous-time systems which are asymptotically stable. The first method is to solve a linear optimization problem on a compact and bounded set. The proposed linear programming based algorithm delivers a CPA1
Method and system of filtering and recommending documents
Energy Technology Data Exchange (ETDEWEB)
Patton, Robert M.; Potok, Thomas E.
2016-02-09
Disclosed is a method and system for discovering documents using a computer and providing a small set of the most relevant documents to the attention of a human observer. Using the method, the computer obtains a seed document from the user and generates a seed document vector using term frequency-inverse corpus frequency weighting. A keyword index for a plurality of source documents can be compared with the weighted terms of the seed document vector. The comparison is then filtered to reduce the number of documents, which define an initial subset of the source documents. Initial subset vectors are generated and compared to the seed document vector to obtain a similarity value for each comparison. Based on the similarity value, the method then recommends one or more of the source documents.
AMADEUS on-line trigger and filtering methods
Energy Technology Data Exchange (ETDEWEB)
Neff, M. [Erlangen Centre for Astroparticle Physics (ECAP), Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Physikalisches Institut, Erwin-Rommel-Strasse 1, D-91058 Erlangen (Germany)], E-mail: max.neff@physik.uni-erlangen.de; Anton, G.; Graf, K.; Hoessl, J.; Katz, U.; Lahmann, R.; Richardt, C. [Erlangen Centre for Astroparticle Physics (ECAP), Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Physikalisches Institut, Erwin-Rommel-Strasse 1, D-91058 Erlangen (Germany)
2009-06-01
AMADEUS is a system designed to investigate the method of acoustic particle detection for high energy neutrinos and the acoustic environment in the deep sea as part of the ANTARES neutrino telescope. In this context, six local clusters of six acoustic sensors each were integrated into the ANTARES infrastructure. The first three clusters have been taking data since December 2007 and the second three since the completion of ANTARES in May 2008. In the paper, the methods used for the on-line triggering and filtering of the data acquired with the AMADEUS set-up are described. On-shore, a dedicated computer-cluster is used to control the off-shore DAQ hardware, to process and store the acoustic data arriving from the sensors. On this cluster different data filtering schemes and triggers are implemented. Transient signals are selected by a variable threshold, which is self-adjusting to the changing conditions of the deep sea. For bipolar pulses-the characteristic acoustic signature of a neutrino-a pattern recognition is used based on cross-correlating the output of the sensors with a pre-defined bipolar pulse. To study the characteristics of the ambient noise in the deep sea an amount of unfiltered data is stored in regular intervals.
Matched-filtering Line Search Methods Applied to Suzaku Data
Miyazaki, Naoto; Enoto, Teruaki; Axelsson, Magnus; Ohashi, Takaya
2016-01-01
A detailed search for emission and absorption lines and assessing their upper limits are performed for Suzaku data. The method utilizes a matched-filtering approach to maximize the signal-to-noise ratio for a given energy resolution, which could be applicable to many types of line search. We first applied it to well-known AGN spectra that have been reported to have ultra-fast outflows, and find that our results are consistent with previous findings at the ~3{\\sigma} level. We proceeded to search for emission and absorption features in the two bright magnetars 4U 0142+61 and 1RXS J1708-4009, applying the filtering method to Suzaku data. We found that neither source showed any significant indication of line features, even using long Suzaku observations and dividing their spectra into spin phases. The upper limits on the equivalent width of emission/absorption lines are constrained to be a few eV at ~1 keV, and a few hundreds of eV at ~10 keV. This strengthens previous reports that persistently bright magnetars ...
Electrically heated particulate filter preparation methods and systems
Gonze, Eugene V [Pinckney, MI
2012-01-31
A control system that controls regeneration of a particulate filter is provided. The system generally includes a fuel control module that controls injection of fuel into exhaust that passes through the particulate filter. A regeneration module controls current to the particulate filter to initiate regeneration after the fuel has been injected into the exhaust.
A Novel Method of Edge Filter Linear Demodulation Using Long Period Grating in Fiber Sensor System
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
A novel method of linear demodulation based on edge filter is presented. An experimental system is built up in which LPG is used as the edge filter. We achieve linear demodulation with a bandwidth of 5nm.
Method for Improving Indoor Positioning Accuracy Using Extended Kalman Filter
Directory of Open Access Journals (Sweden)
Seoung-Hyeon Lee
2016-01-01
Full Text Available Beacons using bluetooth low-energy (BLE technology have emerged as a new paradigm of indoor positioning service (IPS because of their advantages such as low power consumption, miniaturization, wide signal range, and low cost. However, the beacon performance is poor in terms of the indoor positioning accuracy because of noise, motion, and fading, all of which are characteristics of a bluetooth signal and depend on the installation location. Therefore, it is necessary to improve the accuracy of beacon-based indoor positioning technology by fusing it with existing indoor positioning technology, which uses Wi-Fi, ZigBee, and so forth. This study proposes a beacon-based indoor positioning method using an extended Kalman filter that recursively processes input data including noise. After defining the movement of a smartphone on a flat two-dimensional surface, it was assumed that the beacon signal is nonlinear. Then, the standard deviation and properties of the beacon signal were analyzed. According to the analysis results, an extended Kalman filter was designed and the accuracy of the smartphone’s indoor position was analyzed through simulations and tests. The proposed technique achieved good indoor positioning accuracy, with errors of 0.26 m and 0.28 m from the average x- and y-coordinates, respectively, based solely on the beacon signal.
DCT domain filtering method for multi-antenna code acquisition
Institute of Scientific and Technical Information of China (English)
Xiaojie Li; Luping Xu; Shibin Song; Hua Zhang
2013-01-01
For global navigation satel ite system (GNSS) signals in Gaussian and Rayleigh fading channel, a novel signal detection al-gorithm is proposed. Under the low frequency uncertainty case, af-ter performing discrete cosine transform (DCT) to the outputs of the partial matched filter (PMF) for every antenna, the high order com-ponents in the transforming domain wil be filtered, then the equal-gain (EG) combination for the inverse discrete cosine transform (IDCT) reconstructed signal would be done subsequently. Thus, due to the different frequency distribution characteristics between the noise and signals, after EG combination, the energy of signals has almost no loss and the noise energy is greatly reduced. The theoretical analysis and simulation results show that the detection algorithm can effectively improve the signal-to-noise ratio of the captured signal and increase the probability of detection under the same false alarm probability. In addition, it should be pointed out that this method can also be applied to Rayleigh fading channels with moving antenna.
Parallel Variable Distribution Algorithm for Constrained Optimization with Nonmonotone Technique
Directory of Open Access Journals (Sweden)
Congying Han
2013-01-01
Full Text Available A modified parallel variable distribution (PVD algorithm for solving large-scale constrained optimization problems is developed, which modifies quadratic subproblem QPl at each iteration instead of the QPl0 of the SQP-type PVD algorithm proposed by C. A. Sagastizábal and M. V. Solodov in 2002. The algorithm can circumvent the difficulties associated with the possible inconsistency of QPl0 subproblem of the original SQP method. Moreover, we introduce a nonmonotone technique instead of the penalty function to carry out the line search procedure with more flexibly. Under appropriate conditions, the global convergence of the method is established. In the final part, parallel numerical experiments are implemented on CUDA based on GPU (Graphics Processing unit.
Cost Analysis of Different Digital Fir Filter Design Methods
Directory of Open Access Journals (Sweden)
Amninder Singh,
2014-05-01
Full Text Available FIR digital filters are widely used in the communication world. The implementation cost of filter circuit is counted by the number of multipliers & adders used, that decides the chip area. In this paper, design techniques of low pass FIR filter using the different windows are presented. The simulation is done in MATLAB. It is shown that filter designed using Hamming and Blackman windows are better than rest of the windows used. Out of two, Hamming window is better as its transition width is narrow, 0.019 than Blackman, 0.034. Further the performance analysis of Kaiser Window, Equiripple and Minimum phase filters was obtained, for same 0.04 transition width. There is a disparity in implementation cost & area. The minimum phase filter can be implemented with lesser number of filter coefficients with tolerable pass-band, stop-band ripples specifications.
Emergency sacrificial sealing method in filters, equipment, or systems
Brown, Erik P
2014-09-30
A system seals a filter or equipment component to a base and will continue to seal the filter or equipment component to the base in the event of hot air or fire. The system includes a first sealing material between the filter or equipment component and the base; and a second sealing material between the filter or equipment component and the base and proximate the first sealing material. The first sealing material and the second seal material are positioned relative to each other and relative to the filter or equipment component and the base to seal the filter or equipment component to the base and upon the event of fire the second sealing material will be activated and expand to continue to seal the filter or equipment component to the base in the event of hot air or fire.
Emergency sacrificial sealing method in filters, equipment, or systems
Energy Technology Data Exchange (ETDEWEB)
Brown, Erik P.
2017-02-28
A system seals a filter or equipment component to abase and will continue to seal the filter or equipment component to the base in the event of hot air or fire. The system includes a first sealing material between the filter or equipment component and the base; and a second sealing material between the filter or equipment component and the base and proximate the first sealing material. The first sealing material and the second seal material are positioned relative to each other and relative to the filter or equipment component and the base to seal the filter or equipment component to the base and upon the event of fire the second sealing material will be activated and expand to continue to seal the filter or equipment component to the base in the event of hot air or fire.
Adaptive error covariances estimation methods for ensemble Kalman filters
Energy Technology Data Exchange (ETDEWEB)
Zhen, Yicun, E-mail: zhen@math.psu.edu [Department of Mathematics, The Pennsylvania State University, University Park, PA 16802 (United States); Harlim, John, E-mail: jharlim@psu.edu [Department of Mathematics and Department of Meteorology, The Pennsylvania State University, University Park, PA 16802 (United States)
2015-08-01
This paper presents a computationally fast algorithm for estimating, both, the system and observation noise covariances of nonlinear dynamics, that can be used in an ensemble Kalman filtering framework. The new method is a modification of Belanger's recursive method, to avoid an expensive computational cost in inverting error covariance matrices of product of innovation processes of different lags when the number of observations becomes large. When we use only product of innovation processes up to one-lag, the computational cost is indeed comparable to a recently proposed method by Berry–Sauer's. However, our method is more flexible since it allows for using information from product of innovation processes of more than one-lag. Extensive numerical comparisons between the proposed method and both the original Belanger's and Berry–Sauer's schemes are shown in various examples, ranging from low-dimensional linear and nonlinear systems of SDEs and 40-dimensional stochastically forced Lorenz-96 model. Our numerical results suggest that the proposed scheme is as accurate as the original Belanger's scheme on low-dimensional problems and has a wider range of more accurate estimates compared to Berry–Sauer's method on L-96 example.
Particle Filtering Equalization Method for a Satellite Communication Channel
Directory of Open Access Journals (Sweden)
Amblard Pierre-Olivier
2004-01-01
Full Text Available We propose the use of particle filtering techniques and Monte Carlo methods to tackle the in-line and blind equalization of a satellite communication channel. The main difficulties encountered are the nonlinear distortions caused by the amplifier stage in the satellite. Several processing methods manage to take into account these nonlinearities but they require the knowledge of a training input sequence for updating the equalizer parameters. Blind equalization methods also exist but they require a Volterra modelization of the system which is not suited for equalization purpose for the present model. The aim of the method proposed in the paper is also to blindly restore the emitted message. To reach this goal, a Bayesian point of view is adopted. Prior knowledge of the emitted symbols and of the nonlinear amplification model, as well as the information available from the received signal, is jointly used by considering the posterior distribution of the input sequence. Such a probability distribution is very difficult to study and thus motivates the implementation of Monte Carlo simulation methods. The presentation of the equalization method is cut into two parts. The first part solves the problem for a simplified model, focusing on the nonlinearities of the model. The second part deals with the complete model, using sampling approaches previously developed. The algorithms are illustrated and their performance is evaluated using bit error rate versus signal-to-noise ratio curves.
Spreading Speed for a Periodic Reaction-diffusion Model with Nonmonotone Birth Function
Institute of Scientific and Technical Information of China (English)
HUANG Ye-hui; WENG Pei-xuan
2012-01-01
A reaction-diffusion model for a single spccies with age structure and nonlocal reaction for periodic time t is derived.Some results about the model with monotone birth function are firstly introduced,and then by constructing two auxiliary equations and squeezing method,the spreading speed for the system with nonmonotone birth function is obtained.
8th International Workshop on Non-Monotonic Reasoning
Truszczynski, Mirek
2000-01-01
The papers gathered in this collection were presented at the 8th International Workshop on Nonmonotonic Reasoning, NMR2000. The series was started by John McCarthy in 1978. The first international NMR workshop was held at Mohonk Mountain House, New Paltz, New York in June, 1984, and was organized by Ray Reiter and Bonnie Webber. In the last 10 years the area of nonmonotonic reasoning has seen a number of important developments. Significant theoretical advances were made in the understanding of general abstract principles underlying nonmonotonicity. Key results on the expressibility and computational complexity of nonmonotonic logics were established. The role of nonmonotonic reasoning in belief revision, abduction, reasoning about action, planing and uncertainty was further clarified. Several successful NMR systems were built and used in applications such as planning, scheduling, logic programming and constraint satisfaction. The papers in the proceedings reflect these recent advances in the field. They are g...
Robust and Adaptive Block Tracking Method Based on Particle Filter
Directory of Open Access Journals (Sweden)
Bin Sun
2015-10-01
Full Text Available In the field of video analysis and processing, object tracking is attracting more and more attention especially in traffic management, digital surveillance and so on. However problems such as objects’ abrupt motion, occlusion and complex target structures would bring difficulties to academic study and engineering application. In this paper, a fragmentsbased tracking method using the block relationship coefficient is proposed. In this method, we use particle filter algorithm and object region is divided into blocks initially. The contribution of this method is that object features are not extracted just from a single block, the relationship between current block and its neighbor blocks are extracted to describe the variation of the block. Each block is weighted according to the block relationship coefficient when the block is voted on the most matched region in next frame. This method can make full use of the relationship between blocks. The experimental results demonstrate that our method can provide good performance in condition of occlusion and abrupt posture variation.
Directory of Open Access Journals (Sweden)
Marija Kaevska
2015-09-01
The described protocol for filter elution is recommended, and the use of the PowerWater DNA isolation kit for the highest mycobacterial DNA yield from water samples. The described protocol is suitable for parallel detection of mycobacteria using cultivation.
Method of producing monolithic ceramic cross-flow filter
Energy Technology Data Exchange (ETDEWEB)
Larsen, D.A.; Bacchi, D.P.; Connors, T.F.; Collins, E.L. III
1998-02-10
Ceramic filter of various configuration have been used to filter particulates from hot gases exhausted from coal-fired systems. Prior ceramic cross-flow filters have been favored over other types, but those previously have been assemblies of parts somehow fastened together and consequently subject often to distortion or delamination on exposure hot gas in normal use. The present new monolithic, seamless, cross-flow ceramic filters, being of one-piece construction, are not prone to such failure. Further, these new products are made by a novel casting process which involves the key steps of demolding the ceramic filter green body so that none of the fragile inner walls of the filter is cracked or broken. 2 figs.
Method of producing monolithic ceramic cross-flow filter
Energy Technology Data Exchange (ETDEWEB)
Larsen, David A. (Clifton Park, NY); Bacchi, David P. (Schenectady, NY); Connors, Timothy F. (Watervliet, NY); Collins, III, Edwin L. (Albany, NY)
1998-01-01
Ceramic filter of various configuration have been used to filter particulates from hot gases exhausted from coal-fired systems. Prior ceramic cross-flow filters have been favored over other types, but those previously horn have been assemblies of parts somehow fastened together and consequently subject often to distortion or delamination on exposure hot gas in normal use. The present new monolithic, seamless, cross-flow ceramic filters, being of one-piece construction, are not prone to such failure. Further, these new products are made by novel casting process which involves the key steps of demolding the ceramic filter green body so that none of the fragile inner walls of the filter is cracked or broken.
Filtering apparatus and method for mixing, extraction and/or separation
DEFF Research Database (Denmark)
2013-01-01
The present invention relates to a filtering apparatus and method for mixing a compound of solid and fluid phases, separating the phases and/or extracting fluid from the compound. One embodiment of the invention discloses a filtering apparatus comprising a first filter section accommodating a fir...... in a beer brewing procedure....
Filtering apparatus and method for mixing, extraction and/or separation
DEFF Research Database (Denmark)
2013-01-01
The present invention relates to a filtering apparatus and method for mixing a compound of solid and fluid phases, separating the phases and/or extracting fluid from the compound. One embodiment of the invention discloses a filtering apparatus comprising a first filter section accommodating a first...
Cătălin LUPU
2014-01-01
This article presents the development of optimal filters through covolution methods, necessary for restoring, correcting and improving fingerprints acquired from a sensor, able to provide the most ideal image in the output. After the image was binarized and equalized, Canny filter is applied in order to: eliminate the noise (filtering the image with a Gaussian filter), non-maxima suppression, module gradient adaptive binarization and extension edge points edges by hysteresis. The resulting i...
Cătălin LUPU
2014-01-01
This article presents the development of optimal filters through covolution methods, necessary for restoring, correcting and improving fingerprints acquired from a sensor, able to provide the most ideal image in the output. After the image was binarized and equalized, Canny filter is applied in order to: eliminate the noise (filtering the image with a Gaussian filter), non-maxima suppression, module gradient adaptive binarization and extension edge points edges by hysteresis. The resulting i...
Emotion Recognition of Speech Signals Based on Filter Methods
Directory of Open Access Journals (Sweden)
Narjes Yazdanian
2016-10-01
Full Text Available Speech is the basic mean of communication among human beings.With the increase of transaction between human and machine, necessity of automatic dialogue and removing human factor has been considered. The aim of this study was to determine a set of affective features the speech signal is based on emotions. In this study system was designs that include three mains sections, features extraction, features selection and classification. After extraction of useful features such as, mel frequency cepstral coefficient (MFCC, linear prediction cepstral coefficients (LPC, perceptive linear prediction coefficients (PLP, ferment frequency, zero crossing rate, cepstral coefficients and pitch frequency, Mean, Jitter, Shimmer, Energy, Minimum, Maximum, Amplitude, Standard Deviation, at a later stage with filter methods such as Pearson Correlation Coefficient, t-test, relief and information gain, we came up with a method to rank and select effective features in emotion recognition. Then Result, are given to the classification system as a subset of input. In this classification stage, multi support vector machine are used to classify seven type of emotion. According to the results, that method of relief, together with multi support vector machine, has the most classification accuracy with emotion recognition rate of 93.94%.
3D Wavelet-Based Filter and Method
Moss, William C.; Haase, Sebastian; Sedat, John W.
2008-08-12
A 3D wavelet-based filter for visualizing and locating structural features of a user-specified linear size in 2D or 3D image data. The only input parameter is a characteristic linear size of the feature of interest, and the filter output contains only those regions that are correlated with the characteristic size, thus denoising the image.
Distortion Parameters Analysis Method Based on Improved Filtering Algorithm
Directory of Open Access Journals (Sweden)
ZHANG Shutuan
2013-10-01
Full Text Available In order to realize the accurate distortion parameters test of aircraft power supply system, and satisfy the requirement of corresponding equipment in the aircraft, the novel power parameters test system based on improved filtering algorithm is introduced in this paper. The hardware of the test system has the characters of s portable and high-speed data acquisition and processing, and the software parts utilize the software Labwindows/CVI as exploitation software, and adopt the pre-processing technique and adding filtering algorithm. Compare with the traditional filtering algorithm, the test system adopted improved filtering algorithm can help to increase the test accuracy. The application shows that the test system with improved filtering algorithm can realize the accurate test results, and reach to the design requirements.
Method and System for Temporal Filtering in Video Compression Systems
Lu, Ligang; He, Drake; Jagmohan, Ashish; Sheinin, Vadim
2011-01-01
Three related innovations combine improved non-linear motion estimation, video coding, and video compression. The first system comprises a method in which side information is generated using an adaptive, non-linear motion model. This method enables extrapolating and interpolating a visual signal, including determining the first motion vector between the first pixel position in a first image to a second pixel position in a second image; determining a second motion vector between the second pixel position in the second image and a third pixel position in a third image; determining a third motion vector between the first pixel position in the first image and the second pixel position in the second image, the second pixel position in the second image, and the third pixel position in the third image using a non-linear model; and determining a position of the fourth pixel in a fourth image based upon the third motion vector. For the video compression element, the video encoder has low computational complexity and high compression efficiency. The disclosed system comprises a video encoder and a decoder. The encoder converts the source frame into a space-frequency representation, estimates the conditional statistics of at least one vector of space-frequency coefficients with similar frequencies, and is conditioned on previously encoded data. It estimates an encoding rate based on the conditional statistics and applies a Slepian-Wolf code with the computed encoding rate. The method for decoding includes generating a side-information vector of frequency coefficients based on previously decoded source data and encoder statistics and previous reconstructions of the source frequency vector. It also performs Slepian-Wolf decoding of a source frequency vector based on the generated side-information and the Slepian-Wolf code bits. The video coding element includes receiving a first reference frame having a first pixel value at a first pixel position, a second reference frame
Fusion of the Dimensionless Parameters and Filtering Methods in Rotating Machinery Fault Diagnosis
Directory of Open Access Journals (Sweden)
Jianbin Xiong
2014-05-01
Full Text Available For the problem of large dimensionless index fluctuations in rotating machinery complex fault and that the corresponding scope is difficult to determine. In this paper proposes a rotating machinery complex fault method that combined dimensionless and the least squares method filtering. This method implementation filtering and determine the scope of the dimensionless index. By doing experiments with 8 kinds of bearing failure data of petrochemical rotary sets, comparing four filtering methods, the scope of the dimensionless index was established, and the text combined dimensionless index respectively with Kalman (EKF, the weighted average, moving average, the least squares method filtering
A novel optimized LCL-filter designing method for grid connected converter
DEFF Research Database (Denmark)
Guohong, Zeng; Rasmussen, Tonny Wederberg; Teodorescu, Remus
2010-01-01
capacity of all filter components, with clear physical meaning of minimum cost and volume, a set of optimal values of attenuation ratio and inductancesplit- ratio is obtained for deciding all LCL-filter parameters. With this method, filter overall capacity can be minimized while the grid limit of switching......This paper presents a new LCL-filters optimized designing method for grid connected voltage source converter. This method is based on the analysis of converter output voltage components and inherent relations among LCL-filter parameters. By introducing an optimizing index of equivalent total...... frequency distortion is fulfilled. Compared to the existing methods, the proposed method contains only four steps without try-and-error process, so it is efficient and easy to implement. Simulation results of a 50kVA grid-connected inverter with two sets of LCL-filter parameters under different optimizing...
Filtering Method for Location Estimation of an Underwater Robot
Directory of Open Access Journals (Sweden)
Nak Yong Ko
2014-05-01
Full Text Available This paper describes an application of extended Kalman filter(EKF for localization of an underwater robot. For the application, linearized model of robot motion and sensor measurement are derived. Like usual EKF, the method is recursion of two main steps: the time update(or prediction and measurement update. The measurement update uses exteroceptive sensors such as four acoustic beacons and a pressure sensor. The four beacons provide four range data from these beacons to the robot and pressure sensor does the depth data of the robot. One of the major contributions of the paper is suggestion of two measurement update approaches. The first approach corrects the predicted states using the measurement data individually. The second one corrects the predicted state using the measurement data collectively. The simulation analysis shows that EKF outperforms least squares or odometry based dead-reckoning in the precision and robustness of the estimation. Also, EKF with collective measurement update brings out better accuracy than the EKF with individual measurement update.
Bayesian signal processing classical, modern, and particle filtering methods
Candy, James V
2016-01-01
This book aims to give readers a unified Bayesian treatment starting from the basics (Baye's rule) to the more advanced (Monte Carlo sampling), evolving to the next-generation model-based techniques (sequential Monte Carlo sampling). This next edition incorporates a new chapter on "Sequential Bayesian Detection," a new section on "Ensemble Kalman Filters" as well as an expansion of Case Studies that detail Bayesian solutions for a variety of applications. These studies illustrate Bayesian approaches to real-world problems incorporating detailed particle filter designs, adaptive particle filters and sequential Bayesian detectors. In addition to these major developments a variety of sections are expanded to "fill-in-the gaps" of the first edition. Here metrics for particle filter (PF) designs with emphasis on classical "sanity testing" lead to ensemble techniques as a basic requirement for performance analysis. The expansion of information theory metrics and their application to PF designs is fully developed an...
A new greedy search method for the design of digital IIR filter
Directory of Open Access Journals (Sweden)
Ranjit Kaur
2015-07-01
Full Text Available A new greedy search method is applied in this paper to design the optimal digital infinite impulse response (IIR filter. The greedy search method is based on binary successive approximation (BSA and evolutionary search (ES. The suggested greedy search method optimizes the magnitude response and the phase response simultaneously and also finds the lowest order of the filter. The order of the filter is controlled by a control gene whose value is also optimized along with the filter coefficients to obtain optimum order of designed IIR filter. The stability constraints of IIR filter are taken care of during the design procedure. To determine the trade-off relationship between conflicting objectives in the non-inferior domain, the weighting method is exploited. The proposed approach is effectively applied to solve the multiobjective optimization problems of designing the digital low-pass (LP, high-pass (HP, bandpass (BP, and bandstop (BS filters. It has been demonstrated that this technique not only fulfills all types of filter performance requirements, but also the lowest order of the filter can be found. The computational experiments show that the proposed approach gives better digital IIR filters than the existing evolutionary algorithm (EA based methods.
Standardized methods for in-place filter testing
Energy Technology Data Exchange (ETDEWEB)
Dykes, M.; Fretthold, J.K.; Slawski, J.
1997-08-01
The conference minutes of a US DOE meeting held on in-place filter testing are presented. The purpose of the conference was to transfer technical in-place testing knowledge throughout the DOE complex. Major items discussed included purchase requisitions, in-place testing, instrumentation, and in-place test personnel qualifications and training. Future actions identified by conference attendees centered on establishing complex-wide DOE policies on training, inspection and testing, and filter specifications.
DEFF Research Database (Denmark)
Lu, Xiaonan; Sun, Kai; Huang, Lipei
2014-01-01
to the conventional active damping approaches, the biquad filter based active damping method does not require additional sensors and control loops. Meanwhile, the multiple instable closed-loop poles of the parallel inverter system can be moved to the stable region simultaneously. Real-time simulations based on dSPACE...
A Quantitative Analysis on Two RFS-Based Filtering Methods for Multicell Tracking
Directory of Open Access Journals (Sweden)
Yayun Ren
2014-01-01
Full Text Available Multiobject filters developed from the theory of random finite sets (RFS have recently become well-known methods for solving multiobject tracking problem. In this paper, we present two RFS-based filtering methods, Gaussian mixture probability hypothesis density (GM-PHD filter and multi-Bernoulli filter, to quantitatively analyze their performance on tracking multiple cells in a series of low-contrast image sequences. The GM-PHD filter, under linear Gaussian assumptions on the cell dynamics and birth process, applies the PHD recursion to propagate the posterior intensity in an analytic form, while the multi-Bernoulli filter estimates the multitarget posterior density through propagating the parameters of a multi-Bernoulli RFS that approximates the posterior density of multitarget RFS. Numerous performance comparisons between the two RFS-based methods are carried out on two real cell images sequences and demonstrate that both yield satisfactory results that are in good agreement with manual tracking method.
Nonmonotonic Synaptic Excitation and Imbalanced Inhibition Underlying Cortical Intensity Tuning
Wu, Guangying K.; Li, Pingyang; Tao, Huizhong W.; Zhang, Li I.
2006-01-01
Intensity-tuned neurons, characterized by their nonmonotonic response-level function, may play important roles in the encoding of sound intensity-related information. The synaptic mechanisms underlying intensity-tuning remain yet unclear. Here, in vivo whole-cell recordings in rat auditory cortex revealed that intensity-tuned neurons, mostly clustered in a posterior zone, receive imbalanced tone-evoked excitatory and inhibitory synaptic inputs. Excitatory inputs exhibit nonmonotonic intensity...
Institute of Scientific and Technical Information of China (English)
Fang Zhang; Wenyao Liu; Lin Xia; Jinjiang Wang; Yue Zhu
2009-01-01
Noise reduction is one of the most exciting problems in electronic speckle pattern interferometry. We present a homomorphic partial differential equation filtering method for interferometry fringe patterns. The diffusion speed of the equation is determined based on the fringe density. We test the new method on the computer-simulated fringe pattern and experimentally obtain the fringe pattern, and evaluate its filtering performance. The qualitative and quantitative analysis shows that this technique can filter off the additive and multiplicative noise of the fringe patterns effectively, and avoid blurring high-density fringe. It is more capable of improving the quality of fringe patterns than the classical filtering methods.
A digital filter optimization method for low power digital wireless communication system
Tarumi, Kousuke; Tsujimoto, Taizo; Yasuura, Hiroto
2003-01-01
In this paper, we introduce a design method for a low power digital baseband processing circuit. In particular, we focus on a digital FIR(Finite Impulse Response) filter that is a part of the digital baseband processing. Because the digital filter contains large power consuming components, such as adders and multipliers. We propose a design method to reduce power consumption of the digital FIR filter circuit by optimizing bitwidth of inputs of the mutipliers and the adders. We found that the ...
Directory of Open Access Journals (Sweden)
Wan Yang
2014-04-01
Full Text Available A variety of filtering methods enable the recursive estimation of system state variables and inference of model parameters. These methods have found application in a range of disciplines and settings, including engineering design and forecasting, and, over the last two decades, have been applied to infectious disease epidemiology. For any system of interest, the ideal filter depends on the nonlinearity and complexity of the model to which it is applied, the quality and abundance of observations being entrained, and the ultimate application (e.g. forecast, parameter estimation, etc.. Here, we compare the performance of six state-of-the-art filter methods when used to model and forecast influenza activity. Three particle filters--a basic particle filter (PF with resampling and regularization, maximum likelihood estimation via iterated filtering (MIF, and particle Markov chain Monte Carlo (pMCMC--and three ensemble filters--the ensemble Kalman filter (EnKF, the ensemble adjustment Kalman filter (EAKF, and the rank histogram filter (RHF--were used in conjunction with a humidity-forced susceptible-infectious-recovered-susceptible (SIRS model and weekly estimates of influenza incidence. The modeling frameworks, first validated with synthetic influenza epidemic data, were then applied to fit and retrospectively forecast the historical incidence time series of seven influenza epidemics during 2003-2012, for 115 cities in the United States. Results suggest that when using the SIRS model the ensemble filters and the basic PF are more capable of faithfully recreating historical influenza incidence time series, while the MIF and pMCMC do not perform as well for multimodal outbreaks. For forecast of the week with the highest influenza activity, the accuracies of the six model-filter frameworks are comparable; the three particle filters perform slightly better predicting peaks 1-5 weeks in the future; the ensemble filters are more accurate predicting peaks in
New optimal design method for trap damping sections in grid-connected LCL filters
DEFF Research Database (Denmark)
Beres, Remus Narcis; Wang, Xiongfei; Blaabjerg, Frede;
2014-01-01
A straightforward method is proposed in this paper to optimally design the damping sections of the LCL or LCL plus trap filters. The proposed method simplifies the iterative design procedure of the overall filter while ensuring minimum resonance peaking and smaller capacitor than otherwise would ...
Electrically heated particulate filter diagnostic systems and methods
Gonze, Eugene V [Pinckney, MI
2009-09-29
A system that diagnoses regeneration of an electrically heated particulate filter is provided. The system generally includes a grid module that diagnoses a fault of the grid based on at least one of a current signal and a voltage signal. A diagnostic module at least one of sets a fault status and generates a warning signal based on the fault of the grid.
Generalized Design Method for Voltage-Controlled Current-Mode Multifunction Filters
Directory of Open Access Journals (Sweden)
I. Lattenberg
2009-11-01
Full Text Available In the article, the Generalized Current Follower Transconductance Amplifier (GCFTA element for generalized frequency filter design and a novel active element, the Programmable Current Amplifier (PCA for the realization of the current-mode analog blocks, are presented. The paper also presents a method of general frequency filter design, whereas the basic circuit is a general autonomous circuit using GCFTA, PCA elements and general admittances. The properties of the proposed filter have been verified using PSPICE simulations.
Method for signal decomposition and denoising based on nonuniform cosine-modulated filter banks
Institute of Scientific and Technical Information of China (English)
Xuemei Xie; Li Li; Guangming Shi; Bin Peng
2008-01-01
In this paper,a novel method for signal decomposition and denoising is proposed based on a nonuniform filter bank (NUFB),which is derived from a uniform filter bank.With this method,the signal is firstly decomposed into M subbands using a uniform filter bank.Then according to their energy distribution,the corresponding consecutive filters are merged to compose the nonuniform filters.With the resulting NUFB,the signal can be readily matched and flexibly decomposed according to its power spectrum distribution.As another advantage,this method can be used to detect and remove the narrow-band noise from the corrupted signal.To verify the proposed method,a simulation of extracting the main information of an audio signal and removing its glitch is given.
Deterministic Methods for Filtering, part I: Mean-field Ensemble Kalman Filtering
Law, Kody J H; Tempone, Raul
2014-01-01
This paper provides a proof of convergence of the standard EnKF generalized to non-Gaussian state space models, based on the indistinguishability property of the joint distribution on the ensemble. A density-based deterministic approximation of the mean-field EnKF (MFEnKF) is proposed, consisting of a PDE solver and a quadrature rule. Given a certain minimal order of convergence k between the two, this extends to the deterministic filter approximation, which is therefore asymptotically superior to standard EnKF for d<2k. The fidelity of approximation of the true distribution is also established using an extension of total variation metric to random measures. This is limited by a Gaussian bias term arising from non-linearity/non-Gaussianity of the model, which arises in both deterministic and standard EnKF. Numerical results support and extend the theory.
A Speckle Reduction Filter Using Wavelet-Based Methods for Medical Imaging Application
2001-10-25
A Speckle Reduction Filter using Wavelet-Based Methods for Medical Imaging Application Su...Wavelet-Based Methods for Medical Imaging Application Contract Number Grant Number Program Element Number Author(s) Project Number Task Number Work
Hirose, Tomohiro; Nitta, Norihisa; Tsudagawa, Masaru; Takahashi, Masashi; Murata, Kiyoshi
2011-01-01
To introduce an automatic liver segmentation method that includes a novel filter for multiphase multidetector-row helical computed tomography. We acquired 3-phase multidetector-row computed tomographic scans that included unenhanced, arterial, and portal phases. The liver was segmented using our novel adaptive linear prediction filter designed to reduce the difference between filter input and output values in the liver region and to increase these values outside the liver region. The segmentation algorithm produced a mean dice similarity coefficient (DSC) value of 91.4%. The application of our adaptive linear prediction filter was effective in automatically extracting liver regions.
A new method for detemining the Angstrom turbidity coefficient from broad-band filter measurements.
Utrillas Esteban, Mª Pilar; Pedrós Esteban, Roberto; Martínez Lozano, José Antonio; Tena Sangüesa, Fernando
2000-01-01
In this work, a new method for determining Ångström turbidity coefficients is presented. This method is based on broadband filter irradiance measurements. By combining measurements obtained with different filters it is possible to obtain a single value of the turbidity coefficient representative of the whole measurement range of the pyrheliometer. The results provided by this new method are compared with the original Ångström method and turbidity coefficient values derived by spectroradiometr...
A NEW METHOD TO CALCULATE COMPENSATION CURRENT IN PARALLEL ACTIVE POWER FILTER
Directory of Open Access Journals (Sweden)
Ahmet ALTINTAŞ
2004-03-01
Full Text Available Nowadays, active power filter plays an important role in reducing harmonic current and reactive power in power lines. The reliability and effectiveness of an active power filter depends basically on three characteristics. These are the modulation method, the design characteristics of the PWM modulator and the method implemented to generate compensation current. For the last one, there are many proposed methods. Most of them complicated and hence difficult to implement and adjust. In this study, a new method to calculate compensation current is improved and tested in single-phase parallel active power filter controlled by microcontroller. Experimental and simulation results are presented in the paper.
A novel hypothesis splitting method implementation for multi-hypothesis filters
DEFF Research Database (Denmark)
Bayramoglu, Enis; Ravn, Ole; Andersen, Nils Axel
2013-01-01
The paper presents a multi-hypothesis filter library featuring a novel method for splitting Gaussians into ones with smaller variances. The library is written in C++ for high performance and the source code is open and free1. The multi-hypothesis filters commonly approximate the distribution...
Improved Kalman Filter Method for Measurement Noise Reduction in Multi Sensor RFID Systems
Directory of Open Access Journals (Sweden)
Min Chul Kim
2011-10-01
Full Text Available Recently, the range of available Radio Frequency Identification (RFID tags has been widened to include smart RFID tags which can monitor their varying surroundings. One of the most important factors for better performance of smart RFID system is accurate measurement from various sensors. In the multi-sensing environment, some noisy signals are obtained because of the changing surroundings. We propose in this paper an improved Kalman filter method to reduce noise and obtain correct data. Performance of Kalman filter is determined by a measurement and system noise covariance which are usually called the R and Q variables in the Kalman filter algorithm. Choosing a correct R and Q variable is one of the most important design factors for better performance of the Kalman filter. For this reason, we proposed an improved Kalman filter to advance an ability of noise reduction of the Kalman filter. The measurement noise covariance was only considered because the system architecture is simple and can be adjusted by the neural network. With this method, more accurate data can be obtained with smart RFID tags. In a simulation the proposed improved Kalman filter has 40.1%, 60.4% and 87.5% less Mean Squared Error (MSE than the conventional Kalman filter method for a temperature sensor, humidity sensor and oxygen sensor, respectively. The performance of the proposed method was also verified with some experiments.
Improved Kalman filter method for measurement noise reduction in multi sensor RFID systems.
Eom, Ki Hwan; Lee, Seung Joon; Kyung, Yeo Sun; Lee, Chang Won; Kim, Min Chul; Jung, Kyung Kwon
2011-01-01
Recently, the range of available radio frequency identification (RFID) tags has been widened to include smart RFID tags which can monitor their varying surroundings. One of the most important factors for better performance of smart RFID system is accurate measurement from various sensors. In the multi-sensing environment, some noisy signals are obtained because of the changing surroundings. We propose in this paper an improved Kalman filter method to reduce noise and obtain correct data. Performance of Kalman filter is determined by a measurement and system noise covariance which are usually called the R and Q variables in the Kalman filter algorithm. Choosing a correct R and Q variable is one of the most important design factors for better performance of the Kalman filter. For this reason, we proposed an improved Kalman filter to advance an ability of noise reduction of the Kalman filter. The measurement noise covariance was only considered because the system architecture is simple and can be adjusted by the neural network. With this method, more accurate data can be obtained with smart RFID tags. In a simulation the proposed improved Kalman filter has 40.1%, 60.4% and 87.5% less mean squared error (MSE) than the conventional Kalman filter method for a temperature sensor, humidity sensor and oxygen sensor, respectively. The performance of the proposed method was also verified with some experiments.
A gray-natural logarithm ratio bilateral filtering method for image processing
Institute of Scientific and Technical Information of China (English)
Guanan Chen; Kuntao Yang; Rong Chen; Zhiming Xie
2008-01-01
A new method based on gray-natural logarithm ratio bilateral filtering is presented for image smoothing in this work. A new gray-natural logarithm ratio range filter kernel, leading to adaptive magnitude from image gray distinction information, is pointed out for the bilateral filtering. The new method can not only well restrain noise but also keep much more weak edges and details of an image, and preserve the original color transition of color images. Experimental results show the effectiveness for image denoising with our method.
Nonmonotonic Aging and Memory Retention in Disordered Mechanical Systems
Lahini, Yoav; Gottesman, Omer; Amir, Ariel; Rubinstein, Shmuel M.
2017-02-01
We observe nonmonotonic aging and memory effects, two hallmarks of glassy dynamics, in two disordered mechanical systems: crumpled thin sheets and elastic foams. Under fixed compression, both systems exhibit monotonic nonexponential relaxation. However, when after a certain waiting time the compression is partially reduced, both systems exhibit a nonmonotonic response: the normal force first increases over many minutes or even hours until reaching a peak value, and only then is relaxation resumed. The peak time scales linearly with the waiting time, indicating that these systems retain long-lasting memory of previous conditions. Our results and the measured scaling relations are in good agreement with a theoretical model recently used to describe observations of monotonic aging in several glassy systems, suggesting that the nonmonotonic behavior may be generic and that athermal systems can show genuine glassy behavior.
The filter of choice: filtration method preference among injecting drug users
Directory of Open Access Journals (Sweden)
Keijzer Lenneke
2011-08-01
Full Text Available Abstract Background Injection drug use syringe filters (IDUSF are designed to prevent several complications related to the injection of drugs. Due to their small pore size, their use can reduce the solution's insoluble particle content and thus diminish the prevalence of phlebitis, talcosis.... Their low drug retention discourages from filter reuse and sharing and can thus prevent viral and microbial infections. In France, drug users have access to sterile cotton filters for 15 years and to an IDUSF (the Sterifilt® for 5 years. This study was set up to explore the factors influencing filter preference amongst injecting drug users. Methods Quantitative and qualitative data were gathered through 241 questionnaires and the participation of 23 people in focus groups. Results Factors found to significantly influence filter preference were duration and frequency of injecting drug use, the type of drugs injected and subculture. Furthermore, IDU's rationale for the preference of one type of filter over others was explored. It was found that filter preference depends on perceived health benefits (reduced harms, prevention of vein damage, protection of injection sites, drug retention (low retention: better high, protective mechanism against the reuse of filters; high retention: filter reuse as a protective mechanism against withdrawal, technical and practical issues (filter clogging, ease of use, time needed to prepare an injection and believes (the conviction that a clear solution contains less active compound. Conclusion It was concluded that the factors influencing filter preference are in favour of change; a shift towards the use of more efficient filters can be made through increased availability, information and demonstrations.
Arcasoy, C. C.
1992-11-01
The problem of multi-output, infinite-time, linear time-invariant optimal Kalman-Bucy filter both in continuous and discrete-time cases in frequency domain is addressed. A simple new algorithm is given for the analytical solution to the steady-state gain of the optimum filter based on a transfer function approach. The algorithm is based on spectral factorization of observed spectral density matrix of the filter which generates directly the return-difference matrix of the optimal filter. The method is more direct than by algebraic Riccati equation solution and can easily be implemented on digital computer. The design procedure is illustrated by examples and closed-form solution of ECV and ECA radar tracking filters are considered as an application of the method.
Method for Evaluating Insertion Loss of EMI Filter Connected to Semiconductor Power Converters
Tamate, Michio; Sasaki, Tamiko; Toba, Akio; Matsumoto, Yasushi; Wada, Keiji; Shimizu, Toshihisa
In this paper, to design an EMI filter effectively, a method for insertion loss of an EMI filter connected to a semiconductor power converter is proposed. Conducted EMI noise that flows from the converter should conform to the regulations of an international commission, such as International Electrotechnical Commission (IEC). In order to conform to such regulations, EMI filters have to be connected to power converters. In general, the performance of the EMI filter is evaluated on the basis of the insertion loss of 50Ω measurement system. However, the impedance of the power converters is usually not set to 50Ω. As a result, the EMI filter design is often performed using a trial-and-error method because the noise reduction effect is different from the insertion loss. In this work, for simplicity, a power converter is considered to be a capacitor, instead of a stray capacitor. Then, a method for evaluating the insertion loss of an EMI filter connected to the power converter is proposed. This proposed method is employed using the 50Ω measurement system and the capacitance. The proposed method helps to design the EMI filter because the derived noise reduction effect corresponds to the experimental one.
A New Starting Method of the Hybrid Power Filter for Wind Power Generation Systems with Soft Starter
Yamada, Hiroaki; Hiraki, Eiji; Tanaka, Toshihiko
This paper proposes a new method of starting the hybrid power filter for wind power generation systems with soft starter. In the proposed method, an active filter of the hybrid power filter behaves a resistor for the source current under the starting condition. Thus the inrush phenomena of the passive filter are perfectly suppressed. The basic principle of the proposed starting method is discussed, and then confirmed by digital computer simulation using PSCAD/EMTDC. Simulation results demonstrate that the proposed starting method can overcome the inrush currents for the passive filter, building up the dc voltage of the active filter.
Resampling methods for particle filtering:identical distribution, a new method, and comparable study
Institute of Scientific and Technical Information of China (English)
Tian-cheng LI; Gabriel VILLARRUBIA; Shu-dong SUN; Juan M CORCHADO; Javier BAJO
2015-01-01
Resampling is a critical procedure that is of both theoretical and practical significance for efficient implementation of the particle filter. To gain an insight of the resampling process and the filter, this paper contributes in three further respects as a sequel to the tutorial (Li et al., 2015). First, identical distribution (ID) is established as a general principle for the resampling design, which requires the distribution of particles before and after resampling to be statistically identical. Three consistent met-rics including the (symmetrical) Kullback-Leibler divergence, Kolmogorov-Smirnov statistic, and the sampling variance are introduced for assessment of the ID attribute of resampling, and a corresponding, qualitative ID analysis of representative resampling methods is given. Second, a novel resampling scheme that obtains the optimal ID attribute in the sense of minimum sampling variance is proposed. Third, more than a dozen typical resampling methods are compared via simulations in terms of sample size variation, sampling variance, computing speed, and estimation accuracy. These form a more comprehensive under-standing of the algorithm, providing solid guidelines for either selection of existing resampling methods or new implementations.
Tang, Chen; Wang, Linlin; Yan, Haiqing
2012-07-10
In this paper, we first present the general description for partial differential equations (PDEs) based image processing methods, including the basic idea, the main advantages and disadvantages, a few representative PDE models, and the derivation of PDE models. Then we review our contributions on PDE-based anisotropic filtering methods for electronic speckle pattern interferometry, including the second-order, fourth-order, and coupled nonoriented PDE filtering models and the second-order and coupled nonlinear oriented PDE filtering models. We have summarized the features of each model.
The PLSI Method of Stabilizing Two-Dimensional Nonsymmetric Half-Plane Recursive Digital Filters
Gangatharan N; Reddy PS
2003-01-01
Two-dimensional (2D) recursive digital filters find applications in image processing as in medical X-ray processing. Nonsymmetric half-plane (NSHP) filters have definitely positive magnitude characteristics as opposed to quarter-plane (QP) filters. In this paper, we provide methods for stabilizing the given 2D NSHP polynomial by the planar least squares inverse (PLSI) method. We have proved in this paper that if the given 2D unstable NSHP polynomial and its PLSI are of the same degree, the P...
Borodachev, S. M.
2016-06-01
The simple derivation of recursive least squares (RLS) method equations is given as special case of Kalman filter estimation of a constant system state under changing observation conditions. A numerical example illustrates application of RLS to multicollinearity problem.
A Method to improve line flux and redshift measurements with narrowband filters
Zabl, J; Møller, P; Milvang-Jensen, B; Nilsson, K K; Fynbo, J P U; Fèvre, O Le; Tasca, L A M
2016-01-01
High redshift star-forming galaxies are discovered routinely through a flux excess in narrowband filters (NB) caused by an emission line. In most cases, the width of such filters is broad compared to typical line widths, and the throughput of the filters varies substantially within the bandpass. This leads to substantial uncertainties in redshifts and fluxes that are derived from the observations with one specific NB. In this work we demonstrate that the uncertainty in measured line parameters can be sharply reduced by using repeated observations of the same target field with filters that have slightly different transmittance curves. Such data are routinely collected with some large field imaging cameras that use multiple detectors and a separate filter for each of the detectors. An example is the NB118 data from ESO's VISTA InfraRed CAMera (VIRCAM). We carefully developed and characterized this method to determine more accurate redshift and line flux estimates from the ratio of apparent fluxes measured from ...
A composite passive damping method of the LLCL-filter based grid-tied inverter
DEFF Research Database (Denmark)
Wu, Weimin; Huang, Min; Sun, Yunjie
2012-01-01
that is in parallel with the capacitor of the LCL-filter or with the Lf-Cf resonant circuit of the LLCL-filter, and the RL series damper in series with the grid-side inductor have their own application limits. Thus, a composite passive damped LLCL-filter for the grid-tied inverter is proposed, which can effectively......-factor around the characteristic frequency of the filter and grid impedance. To obtain the Q-factor of a high-order system, an equivalent circuit analysis method is proposed and illustrated through several classical passive damped LCL- and LLCL-filters. It is shown that both the RC parallel damper...
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Representing earthquake ground motion as time varying ARMA model, the instantaneous spectrum can only be determined by the time varying coefficients of the corresponding ARMA model. In this paper, unscented Kalman filter is applied to estimate the time varying coefficients. The comparison between the estimation results of unscented Kalman filter and Kalman filter methods shows that unscented Kalman filter can more precisely represent the distribution of the spectral peaks in time-frequency plane than Kalman filter, and its time and frequency resolution is finer which ensures its better ability to track the local properties of earthquake ground motions and to identify the systems with nonlinearity or abruptness. Moreover, the estimation results of ARMA models with different orders indicate that the theoretical frequency resolving power ofARMA model which was usually ignored in former studies has great effect on the estimation precision of instantaneous spectrum and it should be taken as one of the key factors in order selection of ARMA model.
Method for HEPA filter leak scanning with differentiating aerosol detector
Energy Technology Data Exchange (ETDEWEB)
Kovach, B.J.; Banks, E.M.; Wikoff, W.O. [NUCON International, Inc., Columbus, OH (United States)
1997-08-01
While scanning HEPA filters for leaks with {open_quotes}Off the Shelf{close_quote} aerosol detection equipment, the operator`s scanning speed is limited by the time constant and threshold sensitivity of the detector. This is based on detection of the aerosol density, where the maximum signal is achieved when the scanning probe resides over the pinhole longer than several detector time-constants. Since the differential value of the changing signal can be determined by observing only the first small fraction of the rising signal, using a differentiating amplifier will speed up the locating process. The other advantage of differentiation is that slow signal drift or zero offset will not interfere with the process of locating the leak, since they are not detected. A scanning hand-probe attachable to any NUCON{reg_sign} Aerosol Detector displaying the combination of both aerosol density and differentiated signal was designed. 3 refs., 1 fig.
Directory of Open Access Journals (Sweden)
S. J. Noh
2011-10-01
Full Text Available Data assimilation techniques have received growing attention due to their capability to improve prediction. Among various data assimilation techniques, sequential Monte Carlo (SMC methods, known as "particle filters", are a Bayesian learning process that has the capability to handle non-linear and non-Gaussian state-space models. In this paper, we propose an improved particle filtering approach to consider different response times of internal state variables in a hydrologic model. The proposed method adopts a lagged filtering approach to aggregate model response until the uncertainty of each hydrologic process is propagated. The regularization with an additional move step based on the Markov chain Monte Carlo (MCMC methods is also implemented to preserve sample diversity under the lagged filtering approach. A distributed hydrologic model, water and energy transfer processes (WEP, is implemented for the sequential data assimilation through the updating of state variables. The lagged regularized particle filter (LRPF and the sequential importance resampling (SIR particle filter are implemented for hindcasting of streamflow at the Katsura catchment, Japan. Control state variables for filtering are soil moisture content and overland flow. Streamflow measurements are used for data assimilation. LRPF shows consistent forecasts regardless of the process noise assumption, while SIR has different values of optimal process noise and shows sensitive variation of confidential intervals, depending on the process noise. Improvement of LRPF forecasts compared to SIR is particularly found for rapidly varied high flows due to preservation of sample diversity from the kernel, even if particle impoverishment takes place.
Advanced testing method to evaluate the performance of respirator filter media.
Wang, Qiang; Golshahi, Laleh; Chen, Da-Ren
2016-10-02
Filter media for respirator applications are typically exposed to the cyclic flow condition, which is different from the constant flow condition adopted in filter testing standards. To understand the real performance of respirator filter media in the field it is required to investigate the penetration of particles through respirator filters under cyclic flow conditions representing breathing flow patterns of human beings. This article reports a new testing method for studying the individual effect of breathing frequency (BF) and peak inhalation flow rate (PIFR) on the particle penetration through respirator filter media. The new method includes the use of DMA (Differential Mobility Analyzer)-classified particles having the most penetrating particle size, MPPS (at the constant flowrate of equivalent mean inhalation flow rate, MIFR) as test aerosol. Two condensation particle counters (CPCs) are applied to measure the particle concentrations at the upstream and downstream of test filter media at the same time. Given the 10 Hz sampling time of CPCs, close-to-instantaneous particle penetration could be measured. A pilot study was performed to demonstrate the new testing method. It is found that the effect of BF on the particle penetration of test respirator filter media is of importance at all the tested peak inhalation flow rates (PIFRs), which is different from those reported in the previous work.
A novel method of drift-scanning stars suppression based on the standardized linear filter
Lin, Jianlin; Ping, Xijian; Hou, Guanghua; Ma, Debao
2011-11-01
A large number of stars in the drift-scanning star image have interfered with the detection of small target, this paper proposes an adaptive linear filtering method to achieve the small target detection by suppressing the stars. Firstly, the characteristics of stars, interest target and noise three different representative objects in the star image are analyzed, then the standardized linear filter is constructed to suppress the stars. For the purpose of decreasing the influence region of stars filtering uniformly, a gradient linear filter is constructed to modify the stars suppression method with the standardized linear filter. Then the filter parameter selection method is given. Finally, a multi-frame target track experiment on the real drift-scanning data is made to testify the validity of the proposed method. With the processing results of different methods, it has been showed that the proposed method for suppressing stars with different length and lean angle has a better effect, higher robustness and easier application than the others.
Improving the performance of the prony method using a wavelet domain filter for MRI denoising.
Jaramillo, Rodney; Lentini, Marianela; Paluszny, Marco
2014-01-01
The Prony methods are used for exponential fitting. We use a variant of the Prony method for abnormal brain tissue detection in sequences of T 2 weighted magnetic resonance images. Here, MR images are considered to be affected only by Rician noise, and a new wavelet domain bilateral filtering process is implemented to reduce the noise in the images. This filter is a modification of Kazubek's algorithm and we use synthetic images to show the ability of the new procedure to suppress noise and compare its performance with respect to the original filter, using quantitative and qualitative criteria. The tissue classification process is illustrated using a real sequence of T 2 MR images, and the filter is applied to each image before using the variant of the Prony method.
Improving the Performance of the Prony Method Using a Wavelet Domain Filter for MRI Denoising
Directory of Open Access Journals (Sweden)
Rodney Jaramillo
2014-01-01
Full Text Available The Prony methods are used for exponential fitting. We use a variant of the Prony method for abnormal brain tissue detection in sequences of T2 weighted magnetic resonance images. Here, MR images are considered to be affected only by Rician noise, and a new wavelet domain bilateral filtering process is implemented to reduce the noise in the images. This filter is a modification of Kazubek’s algorithm and we use synthetic images to show the ability of the new procedure to suppress noise and compare its performance with respect to the original filter, using quantitative and qualitative criteria. The tissue classification process is illustrated using a real sequence of T2 MR images, and the filter is applied to each image before using the variant of the Prony method.
An Innovative Method for Dynamic Characterization of Fan FilterUnit Operation.
Energy Technology Data Exchange (ETDEWEB)
Xu, Tengfang
2006-12-21
Fan filter units (FFU) are widely used to deliver re-circulated air while providing filtration control of particle concentration in controlled environments such as cleanrooms, minienvironments, and operating rooms in hospitals. The objective of this paper is to document an innovative method for characterizing operation and control of an individual fan filter unit within its operable conditions. Built upon the draft laboratory method previously published [1] , this paper presents an updated method including a testing procedure to characterize dynamic operation of fan filter units, i.e., steady-state operation conditions determined by varied control schemes, airflow rates, and pressure differential across the units. The parameters for dynamic characterization include total electric power demand, total pressure efficiency, airflow rate, pressure differential across fan filter units, and airflow uniformity.
Directory of Open Access Journals (Sweden)
Cui Jia
2017-05-01
Full Text Available With the purpose of reinforcing correlation analysis of risk assessment threat factors, a dynamic assessment method of safety risks based on particle filtering is proposed, which takes threat analysis as the core. Based on the risk assessment standards, the method selects threat indicates, applies a particle filtering algorithm to calculate influencing weight of threat indications, and confirms information system risk levels by combining with state estimation theory. In order to improve the calculating efficiency of the particle filtering algorithm, the k-means cluster algorithm is introduced to the particle filtering algorithm. By clustering all particles, the author regards centroid as the representative to operate, so as to reduce calculated amount. The empirical experience indicates that the method can embody the relation of mutual dependence and influence in risk elements reasonably. Under the circumstance of limited information, it provides the scientific basis on fabricating a risk management control strategy.
Cui, Jia; Hong, Bei; Jiang, Xuepeng; Chen, Qinghua
2017-05-01
With the purpose of reinforcing correlation analysis of risk assessment threat factors, a dynamic assessment method of safety risks based on particle filtering is proposed, which takes threat analysis as the core. Based on the risk assessment standards, the method selects threat indicates, applies a particle filtering algorithm to calculate influencing weight of threat indications, and confirms information system risk levels by combining with state estimation theory. In order to improve the calculating efficiency of the particle filtering algorithm, the k-means cluster algorithm is introduced to the particle filtering algorithm. By clustering all particles, the author regards centroid as the representative to operate, so as to reduce calculated amount. The empirical experience indicates that the method can embody the relation of mutual dependence and influence in risk elements reasonably. Under the circumstance of limited information, it provides the scientific basis on fabricating a risk management control strategy.
A New Nonmonotonic Trust Region Algorithm for A Class of Unconstraied Nonsmooth Optimization
Institute of Scientific and Technical Information of China (English)
欧宜贵; 侯定丕
2002-01-01
This paper preasents a new trust region algorithm for solving a class of composite nonsmooth optimizations.It is distinguished by the fact that this method does not enforce strict monotonicity of the objective function values at successive itereates and that this method extends the existing results for this type of nonlinear optimization with smooth ,or piecewis somooth,or convex objective functions or their composition It is pyoved that this algorithm is globally convergent under certain conditions.Finally,some numerical results for several optimization problems are reported which show that the nonmonotonic trust region method is competitive with the usual trust region method.
Modeling non-monotone risk aversion using SAHARA utility functions
A. Chen; A. Pelsser; M. Vellekoop
2011-01-01
We develop a new class of utility functions, SAHARA utility, with the distinguishing feature that it allows absolute risk aversion to be non-monotone and implements the assumption that agents may become less risk averse for very low values of wealth. The class contains the well-known exponential and
Reasoning Biases, Non-Monotonic Logics, and Belief Revision
Dutilh Novaes, Catarina; Veluwenkamp, Herman
2017-01-01
A range of formal models of human reasoning have been proposed in a number of fields such as philosophy, logic, artificial intelligence, computer science, psychology, cognitive science etc.: various logics (epistemic logics; non-monotonic logics), probabilistic systems (most notably, but not exclusi
Directory of Open Access Journals (Sweden)
S. J. Noh
2011-04-01
Full Text Available Applications of data assimilation techniques have been widely used to improve hydrologic prediction. Among various data assimilation techniques, sequential Monte Carlo (SMC methods, known as "particle filters", provide the capability to handle non-linear and non-Gaussian state-space models. In this paper, we propose an improved particle filtering approach to consider different response time of internal state variables in a hydrologic model. The proposed method adopts a lagged filtering approach to aggregate model response until uncertainty of each hydrologic process is propagated. The regularization with an additional move step based on Markov chain Monte Carlo (MCMC is also implemented to preserve sample diversity under the lagged filtering approach. A distributed hydrologic model, WEP is implemented for the sequential data assimilation through the updating of state variables. Particle filtering is parallelized and implemented in the multi-core computing environment via open message passing interface (MPI. We compare performance results of particle filters in terms of model efficiency, predictive QQ plots and particle diversity. The improvement of model efficiency and the preservation of particle diversity are found in the lagged regularized particle filter.
Sobsey, M D; Cromeans, T
1985-01-01
To determine whether suspended solids interfere with enteric virus recovery from water by microporous filter methods, the effects of bentonite clay solids at a concentration of 10 nephelometric turbidity units on the recovery of poliovirus type 1 from seeded, activated carbon-treated, filtered tap water were studied. Volumes (500 ml) of virus-laden water at pH 5.5 or 7.5, with and without 50 mM MgCl2, were filtered through 47-mm-diameter, electropositive (Virosorb 1MDS) and electronegative (Filterite) filters that had been pretreated with Tween 80 to minimize direct virus adsorption to filter surfaces. Bentonite solids enhanced virus retention on both types of filters, even under conditions in which viruses were not solids associated. However, bentonite solids also interfered with elution of retained viruses when eluting with 0.3% beef extract-50 mM glycine (pH 9.5). Under some conditions, overall virus recoveries were lower from water with bentonite solids than from solids-free control water. The results of this study indicate that clay turbidity can interfere somewhat with virus recovery by current microporous filter methods. PMID:2988438
Zou, X H; Zhu, Y P; Ren, G Q; Li, G C; Zhang, J; Zou, L J; Feng, Z B; Li, B H
2017-02-20
Objective: To evaluate the significance of bacteria detection with filter paper method on diagnosis of diabetic foot wound infection. Methods: Eighteen patients with diabetic foot ulcer conforming to the study criteria were hospitalized in Liyuan Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology from July 2014 to July 2015. Diabetic foot ulcer wounds were classified according to the University of Texas diabetic foot classification (hereinafter referred to as Texas grade) system, and general condition of patients with wounds in different Texas grade was compared. Exudate and tissue of wounds were obtained, and filter paper method and biopsy method were adopted to detect the bacteria of wounds of patients respectively. Filter paper method was regarded as the evaluation method, and biopsy method was regarded as the control method. The relevance, difference, and consistency of the detection results of two methods were tested. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of filter paper method in bacteria detection were calculated. Receiver operating characteristic (ROC) curve was drawn based on the specificity and sensitivity of filter paper method in bacteria detection of 18 patients to predict the detection effect of the method. Data were processed with one-way analysis of variance and Fisher's exact test. In patients tested positive for bacteria by biopsy method, the correlation between bacteria number detected by biopsy method and that by filter paper method was analyzed with Pearson correlation analysis. Results: (1) There were no statistically significant differences among patients with wounds in Texas grade 1, 2, and 3 in age, duration of diabetes, duration of wound, wound area, ankle brachial index, glycosylated hemoglobin, fasting blood sugar, blood platelet count, erythrocyte sedimentation rate, C-reactive protein, aspartate aminotransferase, serum creatinine, and
Non-monotonic reasoning in conceptual modeling and ontology design: A proposal
CSIR Research Space (South Africa)
Casini, G
2013-06-01
Full Text Available and modeling of defeasible information and non-monotonic reasoning services. Here we formalize a possible way of introducing non-monotonic reasoning into ORM2 schemas, enriching the language with special set of new constraints....
Hydrophobic grid membrane filter method for aerobic plate count in foods: collaborative study.
Entis, P
1986-01-01
Twenty-one laboratories participated in a collaborative study to validate a hydrophobic grid membrane filter (HGMF) method for aerobic plate count by comparing its performance against the AOAC/APHA pour plate method. Raw milk, raw poultry, whole egg powder, flours, and spices were included in the study. Counts obtained by the HGMF and pour plate methods did not differ significantly, except in the case of whole egg powder, for which the HGMF method produced significantly higher counts. The hydrophobic grid membrane filter method for aerobic plate count in foods has been adopted official first action.
A computer-aided method for postproduction tuning of HTS filters
Energy Technology Data Exchange (ETDEWEB)
Zuo Tao; Fang Lan; Yan Shaolin; Zhao Xinjie; Zhou Tiege; You Shitou; Ma Weigang; Yue Hongwei; Xie Qinglian [Department of Electronics, Nankai University, Tianjin 300071 (China)
2007-12-15
The empirical tuning of high temperature superconducting (HTS) filters is usually time-consuming and expensive. A computer-aided tuning method is presented in this paper. By means of optimization, the method diagnoses detuning of individual resonators quantitatively in the tuning process, and then by using neural network models the method is able to give the operator a decision on how much the corresponding tuning screws should be tuned. So, compared with the empirical tuning method, this method can be used to tune the HTS filters accurately with less time and cost.
An allpass filter design method with application to piano string synthesis
Abel, Jonathan S.; Smith, Julius O.; Bensa, Julien
2005-04-01
A nonparametric allpass filter design method for matching a desired group delay as a function of frequency is presented. The technique is useful in physical modeling synthesis of musical instruments exhibiting dispersive wave propagation in which different frequency bands travel at different speeds. While current group delay filter design methods suffer from numerical difficulties except at low filter orders, the technique presented here is numerically robust, producing an allpass filter in cascaded biquad form, and with the filter poles following a smooth loop within the unit circle. The technique was inspired by the observation that a pole-zero pair arranged in allpass form has 2π total group delay when integrated around the unit circle, regardless of the pole location. To match a given group delay characteristic, the method divides the frequency axis into sections containing 2π total group delay, and assigns a pole-zero allpass pair to each. In this way, the method incorporates an order selection technique, and by adding a pure delay to the desired group delay, allows the trading of increased filter order for improved fit to the frequency-dependent group delay. Results are presented for modeling the group delay of a stiff piano string under several computational constraints.
NONLINEAR FILTER METHOD OF GPS DYNAMIC POSITIONING BASED ON BANCROFT ALGORITHM
Institute of Scientific and Technical Information of China (English)
ZHANGQin; TAOBen-zao; ZHAOChao-ying; WANGLi
2005-01-01
Because of the ignored items after linearization, the extended Kalman filter (EKF) becomes a form of suboptimal gradient descent algorithm. The emanative tendency exists in GPS solution when the filter equations are ill-posed. The deviation in the estimation cannot be avoided. Furthermore, the true solution may be lost in pseudorange positioning because the linearized pseudorange equations are partial solutions. To solve the above problems in GPS dynamic positioning by using EKF, a closed-form Kalman filter method called the two-stage algorithm is presented for the nonlinear algebraic solution of GPS dynamic positioning based on the global nonlinear least squares closed algorithm--Bancroft numerical algorithm of American. The method separates the spatial parts from temporal parts during processing the GPS filter problems, and solves the nonlinear GPS dynamic positioning, thus getting stable and reliable dynamic positioning solutions.
Institute of Scientific and Technical Information of China (English)
ZHAO Hui; GAO Ziyou
2005-01-01
This paper presents a unified framework of the nonmonotone convex combination algorithms (such as Frank-Wolfe Algorithm) for solving the traffic assignment problems. Global convergence results are established under mild conditions. The line search procedure used in our algorithm includes the nonmonotone Armijo rule, the nonmonotone Goldstein rule and the nonmonotone Wolfe rule as special cases. So, the new algorithm can be viewed as a generalization of the regular convex combination algorithm.
Directory of Open Access Journals (Sweden)
Shepperd CJ
2014-12-01
Full Text Available Methods based on the analyses of cigarette filters have been used to estimate ‘tar’ and nicotine yields to smokers. These methods rely on the measurement of filtration efficiencies (FEs. However FEs may be influenced by both cigarette design features e.g., type of filter and levels of filter ventilation, and human smoking behaviour factors such as puff flow-rates and cigarette butt lengths. Two filter analysis methods are considered in our study. One is based on the analysis of whole filters using average values of FEs obtained from a range of machine smoking regimes. The other, a ‘part filter’ method, analyses a 10 mm section from the mouth end of the filter where the FE remains relatively constant irrespective of puff flow rates and butt lengths. Human puffing behaviour records were obtained from 10 smokers, each smoking six commercial cigarettes ranging from 1 mg to 12 mg ‘tar’ yields [International Standard (ISO values]. These records were used to drive a human smoke duplicator and the resulting ‘tar’ and nicotine yields obtained from duplication were compared with the estimates obtained from ‘whole’ and ‘part filter’ analysis. The results indicated that whilst both filter methods gave good correlations with nicotine and ‘tar’ yields obtained from smoke duplication, the ‘part filter’ method was less susceptible to the effect of nicotine condensation and changes in FEs and hence gave a more accurate assessment of yields than the ‘whole filter’ method.
Directory of Open Access Journals (Sweden)
B. Kuldeep
2015-06-01
Full Text Available Fractional calculus has recently been identified as a very important mathematical tool in the field of signal processing. Digital filters designed by fractional derivatives give more accurate frequency response in the prescribed frequency region. Digital filters are most important part of multi-rate filter bank systems. In this paper, an improved method based on fractional derivative constraints is presented for the design of two-channel quadrature mirror filter (QMF bank. The design problem is formulated as minimization of L2 error of filter bank transfer function in passband, stopband interval and at quadrature frequency, and then Lagrange multiplier method with fractional derivative constraints is applied to solve it. The proposed method is then successfully applied for the design of two-channel QMF bank with higher order filter taps. Performance of the QMF bank design is then examined through study of various parameters such as passband error, stopband error, transition band error, peak reconstruction error (PRE, stopband attenuation (As. It is found that, the good design can be obtained with the change of number and value of fractional derivative constraint coefficients.
Anandh, K R; Sujatha, C M; Ramakrishnan, S
2014-01-01
Ventricle enlargement is a useful structural biomarker for the diagnosis of Alzheimers Disease (AD). This devastating neurodegenerative disorder results in progression of dementia. Although AD results in the passive increment of ventricle volume, there exists a large overlap in the volume measurements of AD and normal subjects. Hence, shape based analysis of ventricle dilation is appropriate to detect the subtle morphological changes among these two groups. In this work, segmentation of ventricle in Alzheimer MR images is employed using level set method and anisotropic based diffusion filtering. Images considered for this study are preprocessed using filters. Anisotropic based diffusion filtering is employed to extract the edge map. This filtering performs region specific smoothing process using the diffusion coefficient as a function of image gradient. Filtered images are subjected to level set method which employs an improved diffusion rate equation for the level set evolution. Geometric features are extracted from the segmented ventricles. Results show that the diffusion filter could extract edge map with sharp region boundaries. The modified level set method is able to extract the morphological changes in ventricles. The observed morphological changes are distinct for normal and AD subjects (p < 0.0001). It is also observed that the sizes of ventricle in the AD subjects are noticeably enlarged when compared to normal subjects. Features obtained from the segmented ventricles are also clearly distinct and demonstrate the differences in the AD subjects. As ventricle volume and its morphometry are significant biomarkers, this study seems to be clinically relevant.
A NEW SQP-FILTER METHOD FOR SOLVING NONLINEAR PROGRAMMING PROBLEMS
Institute of Scientific and Technical Information of China (English)
Duoquan Li
2006-01-01
In [4],Fletcher and Leyffer present a new method that solves nonlinear programming problems without a penalty function by SQP-Filter algorithm. It has attracted much attention due to its good numerical results. In this paper we propose a new SQP-Filter method which can overcome Maratos effect more effectively. We give stricter acceptant criteria when the iterative points are far from the optimal points and looser ones vice-versa. About this new method,the proof of global convergence is also presented under standard assumptions. Numerical results show that our method is efficient.
Kuenzel, Thomas; Nerlich, Jana; Wagner, Hermann; Rübsamen, Rudolf; Milenkovic, Ivan
2015-01-01
Spherical bushy cells (SBCs) of the anteroventral cochlear nucleus (AVCN) receive input from large excitatory auditory nerve (AN) terminals, the endbulbs of Held, and mixed glycinergic/GABAergic inhibitory inputs. The latter have sufficient potency to block action potential firing in vivo and in slice recordings. However, it is not clear how well the data from slice recordings match the inhibition in the intact brain and how it contributes to complex phenomena such as non-monotonic rate-level functions (RLF). Therefore, we determined the input-output relationship of a model SBC with simulated endbulb inputs and a dynamic inhibitory conductance constrained by recordings in brain slice preparations of hearing gerbils. Event arrival times from in vivo single-unit recordings in gerbils, where 70% of SBC showed non-monotonic RLF, were used as input for the model. Model output RLFs systematically changed from monotonic to non-monotonic shape with increasing strength of tonic inhibition. A limited range of inhibitory synaptic properties consistent with the slice data generated a good match between the model and recorded RLF. Moreover, tonic inhibition elevated the action potentials (AP) threshold and improved the temporal precision of output functions in a SBC model with phase-dependent input conductance. We conclude that activity-dependent, summating inhibition contributes to high temporal precision of SBC spiking by filtering out weak and poorly timed EPSP. Moreover, inhibitory parameters determined in slice recordings provide a good estimate of inhibitory mechanisms apparently active in vivo.
Short Time Uniqueness Results for Solutions of Nonlocal and Non-monotone Geometric Equations
Barles, Guy; Mitake, Hiroyoshi
2010-01-01
We describe a method to show short time uniqueness results for viscosity solutions of general nonlocal and non-monotone second-order geometric equations arising in front propagation problems. Our method is based on some lower gradient bounds for the solution. These estimates are crucial to obtain regularity properties of the front, which allow to deal with nonlocal terms in the equations. Applications to short time uniqueness results for the initial value problems for dislocation type equations, asymptotic equations of a FitzHugh-Nagumo type system and equations depending on the Lebesgue measure of the fronts are presented.
A neural network-based optimal spatial filter design method for motor imagery classification.
Directory of Open Access Journals (Sweden)
Ayhan Yuksel
Full Text Available In this study, a novel spatial filter design method is introduced. Spatial filtering is an important processing step for feature extraction in motor imagery-based brain-computer interfaces. This paper introduces a new motor imagery signal classification method combined with spatial filter optimization. We simultaneously train the spatial filter and the classifier using a neural network approach. The proposed spatial filter network (SFN is composed of two layers: a spatial filtering layer and a classifier layer. These two layers are linked to each other with non-linear mapping functions. The proposed method addresses two shortcomings of the common spatial patterns (CSP algorithm. First, CSP aims to maximize the between-classes variance while ignoring the minimization of within-classes variances. Consequently, the features obtained using the CSP method may have large within-classes variances. Second, the maximizing optimization function of CSP increases the classification accuracy indirectly because an independent classifier is used after the CSP method. With SFN, we aimed to maximize the between-classes variance while minimizing within-classes variances and simultaneously optimizing the spatial filter and the classifier. To classify motor imagery EEG signals, we modified the well-known feed-forward structure and derived forward and backward equations that correspond to the proposed structure. We tested our algorithm on simple toy data. Then, we compared the SFN with conventional CSP and its multi-class version, called one-versus-rest CSP, on two data sets from BCI competition III. The evaluation results demonstrate that SFN is a good alternative for classifying motor imagery EEG signals with increased classification accuracy.
Systematic synthesis of CCCCTA-based T-T filters using NAM expansion method
Li, Yongan; Cao, Rui
2016-06-01
In the light of nullor-mirror models for current-controlled current conveyor trans-conductance amplifier (CCCCTA), initiating the admittance matrices of the Tow-Thomas (T-T) filter, three different types of the T-T filter are synthesised by means of the nodal admittance matrix (NAM) expansion method. The type A filter, which employ one CCCCTA, one grounded resistor and two grounded capacitors, has eight different forms, the type B filter, which employ one CCCCTA, two grounded capacitors and a second-generation current-controlled conveyor (CCCII) or an second-generation inverting current-controlled conveyor (ICCCII) or an operational trans-conductance amplifier (OTA), has 64 different forms and the type C filter employing one CCCCTA and two grounded capacitors has eight different forms. In all, 80 voltage-mode/current-mode T-T filter circuits are obtained. Because of using canonic number components, the circuits are highly desirable from the viewpoint of IC fabrication and their parameters can be electronically tuned through tuning bias currents of CCCCTAs. The hand analysis and computer simulation results have been provided to support the synthesis method.
Method and system for training dynamic nonlinear adaptive filters which have embedded memory
Rabinowitz, Matthew (Inventor)
2002-01-01
Described herein is a method and system for training nonlinear adaptive filters (or neural networks) which have embedded memory. Such memory can arise in a multi-layer finite impulse response (FIR) architecture, or an infinite impulse response (IIR) architecture. We focus on filter architectures with separate linear dynamic components and static nonlinear components. Such filters can be structured so as to restrict their degrees of computational freedom based on a priori knowledge about the dynamic operation to be emulated. The method is detailed for an FIR architecture which consists of linear FIR filters together with nonlinear generalized single layer subnets. For the IIR case, we extend the methodology to a general nonlinear architecture which uses feedback. For these dynamic architectures, we describe how one can apply optimization techniques which make updates closer to the Newton direction than those of a steepest descent method, such as backpropagation. We detail a novel adaptive modified Gauss-Newton optimization technique, which uses an adaptive learning rate to determine both the magnitude and direction of update steps. For a wide range of adaptive filtering applications, the new training algorithm converges faster and to a smaller value of cost than both steepest-descent methods such as backpropagation-through-time, and standard quasi-Newton methods. We apply the algorithm to modeling the inverse of a nonlinear dynamic tracking system 5, as well as a nonlinear amplifier 6.
Accurate Gain Flattening Filters Manufactured by Optical Compensation Monitoring Method
Institute of Scientific and Technical Information of China (English)
J. J. Pan; FengQing Zhou; James Guo; Mingjie Zhang; Ming Zhou; Joy Jiang
2003-01-01
GFFs with less than 0.4 dB peak-to-peak error functions are routinely fabricated using commercially available coating machines by utilizing the natural error compensation mechanism of wavelength variable turning point optical monitoring method.
A filtering method to reveal crystalline patterns from atom probe microscopy desorption maps.
Yao, Lan
2016-01-01
A filtering method to reveal the crystallographic information present in Atom Probe Microscopy (APM) data is presented. The method filters atoms based on the time difference between their evaporation and the evaporation of the previous atom. Since this time difference correlates with the location and the local structure of the evaporating atoms on the surface, it can be used to reveal any crystallographic information contained within APM data. The demonstration of this method is illustrated on: •A pure Al specimen for which crystallographic poles are clearly visible on the desorption patterns easily indexed.•Three Fe-15at.% Cr datasets where crystallographic patterns are less obvious and require this filtering method.
Evaluation of sampling methods for Bacillus spore-contaminated HVAC filters.
Calfee, M Worth; Rose, Laura J; Tufts, Jenia; Morse, Stephen; Clayton, Matt; Touati, Abderrahmane; Griffin-Gatchalian, Nicole; Slone, Christina; McSweeney, Neal
2014-01-01
The objective of this study was to compare an extraction-based sampling method to two vacuum-based sampling methods (vacuum sock and 37mm cassette filter) with regards to their ability to recover Bacillus atrophaeus spores (surrogate for Bacillus anthracis) from pleated heating, ventilation, and air conditioning (HVAC) filters that are typically found in commercial and residential buildings. Electrostatic and mechanical HVAC filters were tested, both without and after loading with dust to 50% of their total holding capacity. The results were analyzed by one-way ANOVA across material types, presence or absence of dust, and sampling device. The extraction method gave higher relative recoveries than the two vacuum methods evaluated (p≤0.001). On average, recoveries obtained by the vacuum methods were about 30% of those achieved by the extraction method. Relative recoveries between the two vacuum methods were not significantly different (p>0.05). Although extraction methods yielded higher recoveries than vacuum methods, either HVAC filter sampling approach may provide a rapid and inexpensive mechanism for understanding the extent of contamination following a wide-area biological release incident.
Semantic matchmaking with nonmonotonic description logics
Grimm, S
2009-01-01
Semantic web has grown into a mature field of research. Its methods find innovative applications on and off the World Wide Web. Its underlying technologies have significant impact on adjacent fields of research and on industrial applications. This new book series reports on the state-of-the-art in foundations, methods, and applications of semantic web and its underlying technologies. It is a central forum for the communication of recent developments and comprises research monographs, textbooks and edited volumes on all topics related to the semantic web. In this first volume several non-monoto
New cardiac MRI gating method using event-synchronous adaptive digital filter.
Park, Hodong; Park, Youngcheol; Cho, Sungpil; Jang, Bongryoel; Lee, Kyoungjoung
2009-11-01
When imaging the heart using MRI, an artefact-free electrocardiograph (ECG) signal is not only important for monitoring the patient's heart activity but also essential for cardiac gating to reduce noise in MR images induced by moving organs. The fundamental problem in conventional ECG is the distortion induced by electromagnetic interference. Here, we propose an adaptive algorithm for the suppression of MR gradient artefacts (MRGAs) in ECG leads of a cardiac MRI gating system. We have modeled MRGAs by assuming a source of strong pulses used for dephasing the MR signal. The modeled MRGAs are rectangular pulse-like signals. We used an event-synchronous adaptive digital filter whose reference signal is synchronous to the gradient peaks of MRI. The event detection processor for the event-synchronous adaptive digital filter was implemented using the phase space method-a sort of topology mapping method-and least-squares acceleration filter. For evaluating the efficiency of the proposed method, the filter was tested using simulation and actual data. The proposed method requires a simple experimental setup that does not require extra hardware connections to obtain the reference signals of adaptive digital filter. The proposed algorithm was more effective than the multichannel approach.
Measurement of non-monotonic Casimir forces between silicon nanostructures
Tang, L.; Wang, M.; Ng, C. Y.; Nikolic, M.; Chan, C. T.; Rodriguez, A. W.; Chan, H. B.
2017-01-01
Casimir forces are of fundamental interest because they originate from quantum fluctuations of the electromagnetic field. Apart from controlling this force via the optical properties of materials, a number of novel geometries have been proposed to generate repulsive and/or non-monotonic Casimir forces between bodies separated by vacuum gaps. Experimental realization of these geometries, however, is hindered by the difficulties in alignment when the bodies are brought into close proximity. Here, using an on-chip platform with integrated force sensors and actuators, we circumvent the alignment problem and measure the Casimir force between two surfaces with nanoscale protrusions. We demonstrate that the force depends non-monotonically on the displacement. At some displacements, the Casimir force leads to an effective stiffening of the nanomechanical spring. Our findings pave the way for exploiting the Casimir force in nanomechanical systems using structures of complex and non-conventional shapes.
Hyperspectral microscope imaging (HMI) method, which provides both spatial and spectral characteristics of samples, can be effective for foodborne pathogen detection. The acousto-optic tunable filter (AOTF)-based HMI method can be used to characterize spectral properties of biofilms formed by Salmon...
An analysis method for harmonic resonance and stability of multi-paralleled LCL-filtered inverters
DEFF Research Database (Denmark)
Lu, Minghui; Wang, Xiongfei; Blaabjerg, Frede;
2015-01-01
the resonance characteristic and stability analysis in multi-paralleled grid-connected inverters with LCL-filters. An intuitive analytical method based on equivalent grid impedance has been proposed. The analysis clearly describes the open loop resonance characteristic and provides a relatively easy method...... to define the stable region of multi-inverters system. Experimental results are provided for verifying the theoretical analysis....
In-plane Material Filters for the Discrete Material Optimization Method
DEFF Research Database (Denmark)
Sørensen, Rene; Lund, Erik
2015-01-01
This paper presents in-plane material filters for the Discrete Material Optimization method used for optimizing laminated composite structures. The filters make it possible for engineers to specify a minimum length scale which governs the minimum size of areas with constant material continuity....... Consequently, engineers can target the available production methods, and thereby increase its manufacturability while the optimizer is free to determine which material to apply together with an optimum location, shape, and size of these areas with constant material continuity. By doing so, engineers no longer...... have to group elements together in so-called patches, so to statically impose a minimum length scale. The proposed method imposes the minimum length scale through a standard density filter known from topology optimization of isotropic materials. This minimum length scale is generally referred...
A cognition-based method to ease the computational load for an extended Kalman filter.
Li, Yanpeng; Li, Xiang; Deng, Bin; Wang, Hongqiang; Qin, Yuliang
2014-12-03
The extended Kalman filter (EKF) is the nonlinear model of a Kalman filter (KF). It is a useful parameter estimation method when the observation model and/or the state transition model is not a linear function. However, the computational requirements in EKF are a difficulty for the system. With the help of cognition-based designation and the Taylor expansion method, a novel algorithm is proposed to ease the computational load for EKF in azimuth predicting and localizing under a nonlinear observation model. When there are nonlinear functions and inverse calculations for matrices, this method makes use of the major components (according to current performance and the performance requirements) in the Taylor expansion. As a result, the computational load is greatly lowered and the performance is ensured. Simulation results show that the proposed measure will deliver filtering output with a similar precision compared to the regular EKF. At the same time, the computational load is substantially lowered.
Fuzzy adaptive Kalman filter for indoor mobile target positioning with INS/WSN integrated method
Institute of Scientific and Technical Information of China (English)
杨海; 李威; 罗成名
2015-01-01
Pure inertial navigation system (INS) has divergent localization errors after a long time. In order to compensate the disadvantage, wireless sensor network (WSN) associated with the INS was applied to estimate the mobile target positioning. Taking traditional Kalman filter (KF) as the framework, the system equation of KF was established by the INS and the observation equation of position errors was built by the WSN. Meanwhile, the observation equation of velocity errors was established by the velocity difference between the INS and WSN, then the covariance matrix of Kalman filter measurement noise was adjusted with fuzzy inference system (FIS), and the fuzzy adaptive Kalman filter (FAKF) based on the INS/WSN was proposed. The simulation results show that the FAKF method has better accuracy and robustness than KF and EKF methods and shows good adaptive capacity with time-varying system noise. Finally, experimental results further prove that FAKF has the fast convergence error, in comparison with KF and EKF methods.
Institute of Scientific and Technical Information of China (English)
钱姗姗; 黄静; 马建华; 张华; 刘楠; 张喜乐; 冯前进; 陈武凡
2011-01-01
为获取低剂量CT图像的优质重建,本文提出一种基于投影数据非单调性全变分恢复的低剂量CT重建方法.新方法首先通过非线性Anscombe变换将满足Poisson分布的投影数据转化为近似Gaussian分布,其后对变换后的Gaussian型数据进行非单调性全变分最小化算法（Nonmonotone Total Variation Minimization,NTVM）滤波,最后对Anscombe逆变换数据实现传统的滤波反投影(Filtered Back Projection,FBP) CT重建.仿真和临床低剂量CT重建实验表明,本文方法在噪声清除、伪影抑制和缩短重建时间等方面均有上佳表现.%In order to improve the reconstruction quality of low-dose CT image,a new approach is proposed based on low-dose CT projection restoration in this paper. First, projection data is transformed from Poisson distribution to Gaussian distribution using nonlinear Anscombe transform. Then, the Anscombe transformed data is filtered by an efficient nonmonotone total variation minimization denoising algorithm. Last, the reconstruction is achieved by inverse Anscombe transform and filtered back projection (FBP) method. Simulated and clinical low-dose CT data experimental results demonstrate that a high-quality CT image can be reconstructed.
Modeling argumentation based semantics using non-monotonic reasoning
2005-01-01
Argumentation theory is an alternative style of formalizing non-monotonic reasoning. It seems, argumentation theory is a suitable framework for practical and uncertain reasoning, where arguments support conclusions. Dung's approach is an unifying framework which has played an influential role on argumentation research and Artificial Intelligence. Even though the success of the argumentation theory, it seems that argumentation theory is so far from being efficiently implemented like the logic ...
Application of GIS-Based Spatial Filtering Method for Neural Tube Defects Disease Mapping
Institute of Scientific and Technical Information of China (English)
CHI Wenxue; WANG Jinfeng; LI Xinhu; ZHENG Xiaoying; LIAO Yilan
2007-01-01
This study is to assess the prevalence rates spatial pattern of neural tube defects with geographic information system and spatial filtering technique. A total of 80 infants who diagnosed from neural tube defects in the area being studied between 1998 and 2001 were analyzed. Firstly, the geographic information system (GIS) software ArcGIS was used to map the crude prevalence rates. Secondly, the data were smoothed by the method of spatial filtering. We evaluated that the effect of changes in spatial filtering radius size was assessed by creating maps based on various filtering radius sizes, The 3 miles or larger filtering radius gives better sec tion variability than the 2 and 2.5 miles or smaller ones. The maps produced by the spatial filtering technique indicate that prevalence rates in the villages in the southeastern region are to produce higher prevalence than that in the other regions. The smoothed maps based on Heshun County display a more adequate data representation than the raw prevalence rate map.
Experiments with explicit filtering for LES using a finite-difference method
Lund, T. S.; Kaltenbach, H. J.
1995-01-01
The equations for large-eddy simulation (LES) are derived formally by applying a spatial filter to the Navier-Stokes equations. The filter width as well as the details of the filter shape are free parameters in LES, and these can be used both to control the effective resolution of the simulation and to establish the relative importance of different portions of the resolved spectrum. An analogous, but less well justified, approach to filtering is more or less universally used in conjunction with LES using finite-difference methods. In this approach, the finite support provided by the computational mesh as well as the wavenumber-dependent truncation errors associated with the finite-difference operators are assumed to define the filter operation. This approach has the advantage that it is also 'automatic' in the sense that no explicit filtering: operations need to be performed. While it is certainly convenient to avoid the explicit filtering operation, there are some practical considerations associated with finite-difference methods that favor the use of an explicit filter. Foremost among these considerations is the issue of truncation error. All finite-difference approximations have an associated truncation error that increases with increasing wavenumber. These errors can be quite severe for the smallest resolved scales, and these errors will interfere with the dynamics of the small eddies if no corrective action is taken. Years of experience at CTR with a second-order finite-difference scheme for high Reynolds number LES has repeatedly indicated that truncation errors must be minimized in order to obtain acceptable simulation results. While the potential advantages of explicit filtering are rather clear, there is a significant cost associated with its implementation. In particular, explicit filtering reduces the effective resolution of the simulation compared with that afforded by the mesh. The resolution requirements for LES are usually set by the need to capture
Tresna, W. P.; Isnaeni
2017-04-01
Scanning Electron Microscope (SEM) is a proven instrument for analyzing material in which a 2D image of an object is produced. However, the optimization of a 3D image in the SEM system is usually difficult and costly. There is a simple method to produce a 3D image by using two light sources with a red and a blue filter combined in a certain angle. In this experiment, the authors conducted a simulation of the 3D image formation using anaglyph method by finding the optimum point of shifting the red and blue filters in an SEM image. The method used in this experiment was an image processing that employed a digital manipulation on a certain deviation distance of the central point of the main object. The simulation result of an SEM image with a magnification of 5000 times showed an optimal 3D effect that was achieved when the red filter was shifted by 1 μm to the right and the blue filter was shifted by 1 µm to the left from the central position. The result of this simulation can be used to understand better the viewing angle and the optimal position of the two light sources, i.e. red and blue filter pairs. The produced 3D image can be clearly seen using 3D glasses.
Directory of Open Access Journals (Sweden)
SZOPOS, E.
2012-05-01
Full Text Available This paper presents an iterative method for designing FIR filters that implement arbitrary magnitude characteristics, defined by the user through a set of frequency-magnitude points (frequency samples. The proposed method is based on the non-uniform frequency sampling algorithm. For each iteration a new set of frequency samples is generated, by processing the set used in the previous run; this implies changing the samples location around the previous frequency values and adjusting their magnitude through interpolation. If necessary, additional samples can be introduced, as well. After each iteration the magnitude characteristic of the resulting filter is determined by using the non-uniform DFT and compared with the required one; if the errors are larger than the acceptable levels (set by the user a new iteration is run; the length of the resulting filter and the values of its coefficients are also taken into consideration when deciding a re-run. To demonstrate the efficiency of the proposed method a tool for designing FIR filters that match human audiograms was implemented in LabVIEW. It was shown that the resulting filters have smaller coefficients than the standard one, and can also have lower order, while the errors remain relatively small.
Improved Wavelet-based Spatial Filter of Damage Imaging Method on Composite Structures
Institute of Scientific and Technical Information of China (English)
WANG Yu; YUAN Shenfang; QIU Lei
2011-01-01
Piezoelectric sensor array-based spatial filter technology is a new promising method presented in research area of structural health monitoring(SHM)in the recent years.To apply this method to composite structures and give the actual position of damage,this paper proposes a spatial filter-based damage imaging method improved by complex Shannon wavelet transform.The basic principle of spatial filter is analyzed first.Then,this paper proposes a method of using complex Shannon wavelet transform to construct analytic signals of time domain signals of PZT sensors array.The analytic signals are synthesized depending on the principle of the spatial filter to give a damage imaging in the form of angle-time.A method of converting the damage imaging to the form of angle-distance is discussed.Finally,an aircraft composite oil tank is adopted to validate the damage imaging method.The validating results show that this method can recognize angle and distance of damage successfully.
Monolith filter apparatus and membrane apparatus, and method using same
Energy Technology Data Exchange (ETDEWEB)
Goldsmith, Robert L [Wayland, MA
2012-04-03
A filtration apparatus that separates a liquid feedstock mixed with a gas into filtrate and retentate, the apparatus including at least one filtration device comprised of at least one monolith segment of porous material that defines a plurality of passageways extending longitudinally from a feed face of the structure to a retentate end face. The filtration device contains at least one filtrate conduit within it for carrying filtrate toward a filtrate collection zone, the filtrate conduit providing a path of lower flow resistance than that of alternative flow paths through the porous material of the device. The filtration device can also be utilized as a membrane support for a device for microfiltration, ultrafiltration, nanofiltration, reverse osmosis, or pervaporation. Also disclosed is a method for using such a filtration apparatus.
CRYSTAL FILTERS, *HIGH FREQUENCY, *RADIOFREQUENCY FILTERS, AMPLIFIERS, ELECTRIC POTENTIAL, FREQUENCY, IMPEDANCE MATCHING , INSTRUMENTATION, RADIOFREQUENCY, RADIOFREQUENCY AMPLIFIERS, TEST EQUIPMENT, TEST METHODS
Non-monotonic effect of confinement on the glass transition
Varnik, Fathollah; Franosch, Thomas
2016-04-01
The relaxation dynamics of glass forming liquids and their structure are influenced in the vicinity of confining walls. This effect has mostly been observed to be a monotonic function of the slit width. Recently, a qualitatively new behaviour has been uncovered by Mittal and coworkers, who reported that the single particle dynamics in a hard-sphere fluid confined in a planar slit varies in a non-monotonic way as the slit width is decreased from five to roughly two particle diametres (Mittal et al 2008 Phys. Rev. Lett. 100 145901). In view of the great potential of this effect for applications in those fields of science and industry, where liquids occur under strong confinement (e.g. nano-technology), the number of researchers studying various aspects and consequences of this non-monotonic behaviour has been rapidly growing. This review aims at providing an overview of the research activity in this newly emerging field. We first briefly discuss how competing mechanisms such as packing effects and short-range attraction may lead to a non-monotonic glass transition scenario in the bulk. We then analyse confinement effects on the dynamics of fluids using a thermodynamic route which relates the single particle dynamics to the excess entropy. Moreover, relating the diffusive dynamics to the Widom’s insertion probability, the oscillations of the local dynamics with density at moderate densities are fairly well described. At high densities belonging to the supercooled regime, however, this approach breaks down signaling the onset of strongly collective effects. Indeed, confinement introduces a new length scale which in the limit of high densities and small pore sizes competes with the short-range local order of the fluid. This gives rise to a non-monotonic dependence of the packing structure on confinement, with a corresponding effect on the dynamics of structural relaxation. This non-monotonic effect occurs also in the case of a cone-plate type channel, where the degree
A Method of SAR Target Recognition Based on Gabor Filter and Local Texture Feature Extraction
Directory of Open Access Journals (Sweden)
Wang Lu
2015-12-01
Full Text Available This paper presents a novel texture feature extraction method based on a Gabor filter and Three-Patch Local Binary Patterns (TPLBP for Synthetic Aperture Rader (SAR target recognition. First, SAR images are processed by a Gabor filter in different directions to enhance the significant features of the targets and their shadows. Then, the effective local texture features based on the Gabor filtered images are extracted by TPLBP. This not only overcomes the shortcoming of Local Binary Patterns (LBP, which cannot describe texture features for large scale neighborhoods, but also maintains the rotation invariant characteristic which alleviates the impact of the direction variations of SAR targets on recognition performance. Finally, we use an Extreme Learning Machine (ELM classifier and extract the texture features. The experimental results of MSTAR database demonstrate the effectiveness of the proposed method.
The PLSI Method of Stabilizing Two-Dimensional Nonsymmetric Half-Plane Recursive Digital Filters
Directory of Open Access Journals (Sweden)
Gangatharan N
2003-01-01
Full Text Available Two-dimensional (2D recursive digital filters find applications in image processing as in medical X-ray processing. Nonsymmetric half-plane (NSHP filters have definitely positive magnitude characteristics as opposed to quarter-plane (QP filters. In this paper, we provide methods for stabilizing the given 2D NSHP polynomial by the planar least squares inverse (PLSI method. We have proved in this paper that if the given 2D unstable NSHP polynomial and its PLSI are of the same degree, the PLSI polynomial is always stable, irrespective of whether the coefficients of the given polynomial have relationship among its coefficients or not. Examples are given for 2D first-order and second-order cases to prove our results. The generalization is done for the th order polynomial.
Rajabioun, Mehdi; Nasrabadi, Ali Motie; Shamsollahi, Mohammad Bagher
2017-08-29
Effective connectivity is one of the most important considerations in brain functional mapping via EEG. It demonstrates the effects of a particular active brain region on others. In this paper, a new method is proposed which is based on dual Kalman filter. In this method, firstly by using a brain active localization method (standardized low resolution brain electromagnetic tomography) and applying it to EEG signal, active regions are extracted, and appropriate time model (multivariate autoregressive model) is fitted to extracted brain active sources for evaluating the activity and time dependence between sources. Then, dual Kalman filter is used to estimate model parameters or effective connectivity between active regions. The advantage of this method is the estimation of different brain parts activity simultaneously with the calculation of effective connectivity between active regions. By combining dual Kalman filter with brain source localization methods, in addition to the connectivity estimation between parts, source activity is updated during the time. The proposed method performance has been evaluated firstly by applying it to simulated EEG signals with interacting connectivity simulation between active parts. Noisy simulated signals with different signal to noise ratios are used for evaluating method sensitivity to noise and comparing proposed method performance with other methods. Then the method is applied to real signals and the estimation error during a sweeping window is calculated. By comparing proposed method results in different simulation (simulated and real signals), proposed method gives acceptable results with least mean square error in noisy or real conditions.
Comparison of different filter methods for data assimilation in the unsaturated zone
Lange, Natascha; Berkhahn, Simon; Erdal, Daniel; Neuweiler, Insa
2016-04-01
The unsaturated zone is an important compartment, which plays a role for the division of terrestrial water fluxes into surface runoff, groundwater recharge and evapotranspiration. For data assimilation in coupled systems it is therefore important to have a good representation of the unsaturated zone in the model. Flow processes in the unsaturated zone have all the typical features of flow in porous media: Processes can have long memory and as observations are scarce, hydraulic model parameters cannot be determined easily. However, they are important for the quality of model predictions. On top of that, the established flow models are highly non-linear. For these reasons, the use of the popular Ensemble Kalman filter as a data assimilation method to estimate state and parameters in unsaturated zone models could be questioned. With respect to the long process memory in the subsurface, it has been suggested that iterative filters and smoothers may be more suitable for parameter estimation in unsaturated media. We test the performance of different iterative filters and smoothers for data assimilation with a focus on parameter updates in the unsaturated zone. In particular we compare the Iterative Ensemble Kalman Filter and Smoother as introduced by Bocquet and Sakov (2013) as well as the Confirming Ensemble Kalman Filter and the modified Restart Ensemble Kalman Filter proposed by Song et al. (2014) to the original Ensemble Kalman Filter (Evensen, 2009). This is done with simple test cases generated numerically. We consider also test examples with layering structure, as a layering structure is often found in natural soils. We assume that observations are water content, obtained from TDR probes or other observation methods sampling relatively small volumes. Particularly in larger data assimilation frameworks, a reasonable balance between computational effort and quality of results has to be found. Therefore, we compare computational costs of the different methods as well
Directory of Open Access Journals (Sweden)
E. M.Saad
2011-08-01
Full Text Available Improving data association technique in dense clutter environment for multi-target tracking used in Markov chain Monte Carlo based particle filter (MCMC-PF are discussed in this paper. A new method named Viterbi filtered gate Markov chain Monte Carlo VFG-MCMC is introduced to avoid track swap and to overcome the issue of loosing track to highly maneuvering targets in the presence of more background clutter and false signals. An adaptive search based on Viterbi algorithm is then used to detect the valid filtered data point in each target gate. The detected valid point for each target is applied to the estimation algorithm of MCMC-PF during calculating the sampling weights. This proposed method makes the MCMC interacts only with the valid target that is candidate from the filtered gate and no more calculations are considered for invalid targets. Simulation results demonstrate the effectiveness and better performance when compared to conventional algorithm MCMC-PF.
Thermal Error Modeling of the CNC Machine Tool Based on Data Fusion Method of Kalman Filter
Directory of Open Access Journals (Sweden)
Haitong Wang
2017-01-01
Full Text Available This paper presents a modeling methodology for the thermal error of machine tool. The temperatures predicted by modified lumped-mass method and the temperatures measured by sensors are fused by the data fusion method of Kalman filter. The fused temperatures, instead of the measured temperatures used in traditional methods, are applied to predict the thermal error. The genetic algorithm is implemented to optimize the parameters in modified lumped-mass method and the covariances in Kalman filter. The simulations indicate that the proposed method performs much better compared with the traditional method of MRA, in terms of prediction accuracy and robustness under a variety of operating conditions. A compensation system is developed based on the controlling system of Siemens 840D. Validated by the compensation experiment, the thermal error after compensation has been reduced dramatically.
A clinical evaluation of the RNCA study using Fourier filtering as a preprocessing method
Energy Technology Data Exchange (ETDEWEB)
Robeson, W.; Alcan, K.E.; Graham, M.C.; Palestro, C.; Oliver, F.H.; Benua, R.S.
1984-06-01
Forty-one patients (25 male, 16 female) were studied by Radionuclide Cardangiography (RNCA) in our institution. There were 42 rest studies and 24 stress studies (66 studies total). Sixteen patients were normal, 15 had ASHD, seven had a cardiomyopathy, and three had left-sided valvular regurgitation. Each study was preprocessed using both the standard nine-point smoothing method and Fourier filtering. Amplitude and phase images were also generated. Both preprocessing methods were compared with respect to image quality, border definition, reliability and reproducibility of the LVEF, and cine wall motion interpretation. Image quality and border definition were judged superior by the consensus of two independent observers in 65 of 66 studies (98%) using Fourier filtered data. The LVEF differed between the two processes by greater than .05 in 17 of 66 studies (26%) including five studies in which the LVEF could not be determined using nine-point smoothed data. LV wall motion was normal by both techniques in all control patients by cine analysis. However, cine wall motion analysis using Fourier filtered data demonstrated additional abnormalities in 17 of 25 studies (68%) in the ASHD group, including three uninterpretable studies using nine-point smoothed data. In the cardiomyopathy/valvular heart disease group, ten of 18 studies (56%) had additional wall motion abnormalities using Fourier filtered data (including four uninterpretable studies using nine-point smoothed data). We conclude that Fourier filtering is superior to the nine-point smooth preprocessing method now in general use in terms of image quality, border definition, generation of an LVEF, and cine wall motion analysis. The advent of the array processor makes routine preprocessing by Fourier filtering a feasible technologic advance in the development of the RNCA study.
Directory of Open Access Journals (Sweden)
Mikhail Lvovich Nemchikov
2017-01-01
Full Text Available The author dwells upon the problems of the technical condition of refueling complexes equipment continuous monitoring, which is an important factor in ensuring the safety and regularity of flights. The article deals with the results of the research into the composition and concentration of mechanical impurities from different layers of the regular filter EFB-15/120-104 0615 production number of NGOs "Unit", which has been removed from the supply line TC-1 aviation fuel tank farm from the State Reserve in the refueling tank farm "Vnukovo" and the filter control of Velcon company brand the CDF 230F, which is removed from the tanker, in order to assess their performance and service life prediction using X-ray fluorescence method.Illustrative and graphic research results are given, which allow to assess the effectiveness of the used filters. The assessment measuring of the found elements concentrations in different areas of the test sample: 4sm2 area, 1 cm2 and 0.25 cm2, cut from a cardboard filter area is made. The author determined that the average total Fe concentration on the filter was 8.3 g / m providing the fact that due to the operator information the filter pumped 2,020 m3 or 1,582 tons of fuel. There is also made the estimation of the total amount of Fe, detained in filter, which is 1313 g. It should be noted, according to the appearance and the detected concentration of Fe, its capacity has not been fully exhausted. This allows to receive additional information on the real filter resource, and to use it for solving the problems of filter mod- ernization.The studies have shown the possibility to estimate the amount and composition of impurities, which allows to be sure that this work is promising and possible to be integrated into the practical events to ensure the safe operation of civil aircraft. The publication aims to draw the attention of operators and regulatory authorities to the possibility of using the proposed method to provide a
Energy Technology Data Exchange (ETDEWEB)
Park, M.G.; Kim, Y.H.; Cha, K.H.; Kim, M.K. [Korea Electric Power Research Institute, Taejon (Korea)
1999-07-01
A method is described to develop and H{infinity} filtering method for the dynamic compensation of self-powered neutron detectors normally used for fixed incore instruments. An H{infinity} norm of the filter transfer matrix is used as the optimization criteria in the worst-case estimation error sense. Filter modeling is performed for both continuous- and discrete-time models. The filter gains are optimized in the sense of noise attenuation level of H{infinity} setting. By introducing Bounded Real Lemma, the conventional algebraic Riccati inequalities are converted into Linear Matrix Inequalities (LMIs). Finally, the filter design problem is solved via the convex optimization framework using LMIs. The simulation results show that remarkable improvements are achieved in view of the filter response time and the filter design efficiency. (author). 15 refs., 4 figs., 3 tabs.
Energy Technology Data Exchange (ETDEWEB)
Park, Moon Kyu; Kim, Yong Hee; Cha, Kune Ho; Kim, Myung Ki [KEPCO, KEPRI, Taejon (Korea, Republic of)
1998-10-01
A method is described to develop an H{infinity} filtering method for the dynamic compensation of self-powered neutron detectors normally used for fixed incore instruments. An H{infinity} norm of the filter transfer matrix is used as the optimization criteria in the worst-case estimation error sense. Filter modeling is performed for discrete-time model. The filter gains are optimized in the sense of noise attenuation level of H{infinity} setting. By introducing Bounded Real Lemma, the conventional algebraic Riccati inequalities are converted into Linear Matrix Inequalities (LMIs). Finally, the filter design problem is solved via the convex optimization framework using LMIs. The simulation results show that remarkable improvements are achieved in view of the filter response time and the filter design efficiency.
Joint Spatio-Temporal Filtering Methods for DOA and Fundamental Frequency Estimation
DEFF Research Database (Denmark)
Jensen, Jesper Rindom; Christensen, Mads Græsbøll; Benesty, Jacob
2015-01-01
In this paper, spatio-temporal filtering methods are proposed for estimating the direction-of-arrival (DOA) and fundamental frequency of periodic signals, like those produced by the speech production system and many musical instruments using microphone arrays. This topic has quite recently received...
Design and analysis of planar printed microwave and PBG filters using an FDTD method
DEFF Research Database (Denmark)
Tong, M.S.; Lu, Y.L.; Chen, Y.C.;
2004-01-01
In this paper, various planar printed microwave and photonic band-gap (PBG) filters have been designed and analyzed by applying the finite difference time domain method, together with an unsplit-anisotropic perfectly matched layer technique as treatments of boundary conditions. The implemented...
Design and analysis of planar printed microwave and PBG filters using an FDTD method
DEFF Research Database (Denmark)
Tong, M.S.; Lu, Y.L.; Chen, Y.C.
2004-01-01
In this paper, various planar printed microwave and photonic band-gap (PBG) filters have been designed and analyzed by applying the finite difference time domain method, together with an unsplit-anisotropic perfectly matched layer technique as treatments of boundary conditions. The implemented so...
Software alignment of the BESⅢ main drift chamber using the Kalman Filter method
Institute of Scientific and Technical Information of China (English)
WANG Ji-Ke; MAO Ze-Pu; BIAN Jian-Ming; CAO Guo-Fu; CAO Xue-Xiang; CHEN Shen-Jian; DENG Zi-Yan; FU Cheng-Dong; GAO Yuan-Ning; HE Kang-Lin; HE Miao; HUA Chun-Fei; HUANG Bin; HUANG Xing-Tao; JI Xiao-Bin; LI Fei; LI Hai-Bo; LI Wei-Dong; LIANG Yu-Tie; LIU Chun-Xiu; LIU Huai-Min; LIU Suo; LIU Ying-Jie; MA Qiu-Mei; MA Xiang; MAO Ya-Jun; MO Xiao-Hu; PAN Ming-Hua; PANG Cai-Ying; PING Rong-Gang; QIN Ya-Hong; QIU Jin-Fa; SUN Sheng-Sen; SUN Yong-Zhao; WANG Liang-Liang; WEN Shuo-Pin; WU Ling-Hui; XIE Yu-Guang; XU Min; YAN Liang; YOU Zheng-Yun; YUAN Chang-Zheng; YUAN Ye; ZHANG Bing-Yun; ZHANG Chang-Chun; ZHANG Jian-Yong; ZHANG Xue-Yao; ZHANG Yao; ZHENG Yang-Heng; ZHU Ke-Jun; ZHU Yong-Sheng; ZHU Zhi-Li; ZOU Jia-Heng
2009-01-01
Software alignment is quite important for a tracking detector to reach its ultimate position accuracy and momentum resolution. We developed a new alignment algorithm for the BESⅢ Main Drift Chamber using the Kalman Filter method. Two different types of data which are helix tracks and straight tracks are used to test this algorithm, and the results show that the design and implementation is successful.
ESTIMATE ACCURACY OF NONLINEAR COEFFICIENTS OF SQUEEZEFILM DAMPER USING STATE VARIABLE FILTER METHOD
Institute of Scientific and Technical Information of China (English)
1998-01-01
The estimate model for a nonlinear system of squeeze-film damper (SFD) is described.The method of state variable filter (SVF) is used to estimate the coefficients of SFD.The factors which are critical to the estimate accuracy are discussed.
A NEW METHOD OF CHANNEL FRICTION INVERSION BASED ON KALMAN FILTER WITH UNKNOWN PARAMETER VECTOR
Institute of Scientific and Technical Information of China (English)
CHENG Wei-ping; MAO Gen-hai; LIU Guo-hua
2005-01-01
Channel friction is an important parameter in hydraulic analysis.A channel friction parameter inversion method based on Kalman Filter with unknown parameter vector is proposed.Numerical simulations indicate that when the number of monitoring stations exceeds a critical value, the solution is hardly affected.In addition, Kalman Filter with unknown parameter vector is effective only at unsteady state.For the nonlinear equations, computations of sensitivity matrices are time-costly.Two simplified measures can reduce computing time, but not influence the results.One is to reduce sensitivity matrix analysis time, the other is to substitute for sensitivity matrix.
A method for preventing filters being blocked by clay in a well
Energy Technology Data Exchange (ETDEWEB)
Boldin, B.N.; Borodkina, N.I.; Kodzhoglyan, G.A.; Petrov, A.I.
1983-01-01
A method is proposed for eliminating claying of filters in wells, which includes the application of an easily removed protective coating on the filter and its subsequent destruction by the stratum fluid. It is distinguished by the fact that in order to increase the reliability of coverage through increasing the terms for solution, an acetonformaldehyde resin, hardened by a 35 percent aqueous solution of caustic soda, is used as the protective coating in the following relationship of components, in percent by mass: acetonformaldehyde resin, 94.0 to 97.0 and 35 percent solution of caustic soda, 3.0 to 6.0.
Bds/gps Integrated Positioning Method Research Based on Nonlinear Kalman Filtering
Ma, Y.; Yuan, W.; Sun, H.
2017-09-01
In order to realize fast and accurate BDS/GPS integrated positioning, it is necessary to overcome the adverse effects of signal attenuation, multipath effect and echo interference to ensure the result of continuous and accurate navigation and positioning. In this paper, pseudo-range positioning is used as the mathematical model. In the stage of data preprocessing, using precise and smooth carrier phase measurement value to promote the rough pseudo-range measurement value without ambiguity. At last, the Extended Kalman Filter(EKF), the Unscented Kalman Filter(UKF) and the Particle Filter(PF) algorithm are applied in the integrated positioning method for higher positioning accuracy. The experimental results show that the positioning accuracy of PF is the highest, and UKF is better than EKF.
Wavelet-based method for image filtering using scale-space continuity
Jung, Claudio R.; Scharcanski, Jacob
2001-04-01
This paper proposes a novel technique to reduce noise while preserving edge sharpness during image filtering. This method is based on the image multiresolution decomposition by a discrete wavelet transform, given a proper wavelet basis. In the transform spaces, edges are implicitly located and preserved, at the same time that image noise is filtered out. At each resolution level, geometric continuity is used to preserve edges that are not isolated. Finally, we compare consecutive levels to preserve edges having continuity along scales. As a result, the proposed technique produces a filtered version of the original image, where homogeneous regions appear segmented by well-defined edges. Possible applications include image presegmentation and image denoising.
Contextual filtering method applied to sub-bands of interferometric image decomposition
Belhadj-Aissa, S.; Hocine, F.; Boughacha, M. S.; Belhadj-Aissa, M.
2016-10-01
The precision and accuracy of Digital elevation model and deformation measurement, from SAR interferometry (InSAR/DInSAR) depend mainly on the quality of the interferogram. However, the phase noise, which is mainly due to decorrelation between the images and the speckle, makes the step of phase unwrapping most delicate. In this paper, we propose a filtering method that combines the techniques of decomposition into sub-bands and nonlinear local weights. The Spectral / Contextual filter that we propose, inspired from to Goldstein filter is applied to the sub-bands from the wavelet decomposition. To validate the results, we applied to interferometric products tandem pair ERS1/ERS2 taken in the region of Algiers Algeria.
Low-Cost Design of an FIR Filter by Using a Coefficient Mapping Method
Directory of Open Access Journals (Sweden)
Ming-Chih Chen
2013-01-01
Full Text Available This work presents a novel coefficient mapping method to reduce the area cost of the finite impulse response (FIR filter design, especially for optimizing its coefficients. Being capable of reducing the area cost and improving the filter performance, the proposed mapping method consists of four steps: quantization of coefficients, import of parameters, constitution of prime coefficients with parameters, and constitution of residual coefficients with prime coefficients. Effectiveness of the proposed coefficient mapping method is verified by selecting the 48-tap filter of IS-95 code division multiple access (CDMA standard as the benchmark. Experimental results indicate that the proposed design with canonical signed digit (CSD coefficients can operate at 86 MHz with an area of 241,813 um2, leading to a throughput rate of 1,382 Mbps. Its ratio of throughput/area is 5,715 Kbps/um2, yielding a higher performance than that of previous designs. In summary, the proposed design reduces 5.7% of the total filter area, shortens 25.7% of the critical path delay, and improves 14.8% of the throughput/area by a value over that of the best design reported before.
The overview of damping methods for three-phase grid-tied inverter with LLCL-filter
DEFF Research Database (Denmark)
Huang, Min; Blaabjerg, Frede; Loh, Poh Chiang
2014-01-01
damping, passive damping or even without damping if it is designed conservative. In this paper, an overview of damping methods for three-phase voltage-source grid-tied with LLCL-filter is given. This paper also analyzes damping principle of each method including passive damping and active damping......Compared with LCL filter, an LLCL-filter is characterized with smaller size and lower cost for grid-connected inverters. But this high order filter may also have resonant problem which will affect the system stability. Many methods can be used to alleviate the resonant problem including active...
Meade, Rhiana D; Murray, Anna L; Mittelman, Anjuliee M; Rayner, Justine; Lantagne, Daniele S
2017-02-01
Locally manufactured ceramic water filters are one effective household drinking water treatment technology. During manufacturing, silver nanoparticles or silver nitrate are applied to prevent microbiological growth within the filter and increase bacterial removal efficacy. Currently, there is no recommendation for manufacturers to test silver concentrations of application solutions or filtered water. We identified six commercially available silver test strips, kits, and meters, and evaluated them by: (1) measuring in quintuplicate six samples from 100 to 1,000 mg/L (application range) and six samples from 0.0 to 1.0 mg/L (effluent range) of silver nanoparticles and silver nitrate to determine accuracy and precision; (2) conducting volunteer testing to assess ease-of-use; and (3) comparing costs. We found no method accurately detected silver nanoparticles, and accuracy ranged from 4 to 91% measurement error for silver nitrate samples. Most methods were precise, but only one method could test both application and effluent concentration ranges of silver nitrate. Volunteers considered test strip methods easiest. The cost for 100 tests ranged from 36 to 1,600 USD. We found no currently available method accurately and precisely measured both silver types at reasonable cost and ease-of-use, thus these methods are not recommended to manufacturers. We recommend development of field-appropriate methods that accurately and precisely measure silver nanoparticle and silver nitrate concentrations.
Huang, Lei
2015-09-30
To solve the problem in which the conventional ARMA modeling methods for gyro random noise require a large number of samples and converge slowly, an ARMA modeling method using a robust Kalman filtering is developed. The ARMA model parameters are employed as state arguments. Unknown time-varying estimators of observation noise are used to achieve the estimated mean and variance of the observation noise. Using the robust Kalman filtering, the ARMA model parameters are estimated accurately. The developed ARMA modeling method has the advantages of a rapid convergence and high accuracy. Thus, the required sample size is reduced. It can be applied to modeling applications for gyro random noise in which a fast and accurate ARMA modeling method is required.
The Non-Monotonic Effect of Financing Constraints on Investment
DEFF Research Database (Denmark)
Hirth, Stefan; Viswanatha, Marc
We analyze investment timing in a discrete-time framework with two possible investment dates, which is an extension of the model by Lyandres (2007). While Lyandres could only show non-monotonicity of investment in market frictions, we derive an investment threshold that is U-shaped in the firm's ......'s liquid funds, a result similar to the infinite-horizon model by Boyle and Guthrie (2003). However, due to the tractability of our model, we can more clearly explain the relevant trade-offs leading to the U-shape....
Maria Lousada-Ferreira; Pawel Krzeminski; Stefan Geilvoet; Adrien Moreau; Jose A. Gil; Herman Evenblij; van Lier, Jules B.; van der Graaf, Jaap H.J.M.
2014-01-01
Prevention and removal of fouling is often the most energy intensive process in Membrane Bioreactors (MBRs), responsible for 40% to 50% of the total specific energy consumed in submerged MBRs. In the past decade, methods were developed to quantify and qualify fouling, aiming to support optimization in MBR operation. Therefore, there is a need for an evaluation of the lessons learned and how to proceed. In this article, five different methods for measuring MBR activated sludge filterability an...
Method for providing a polarization filter for processing synthetic aperture radar image data
Dubois, Pascale C. (Inventor); vanZyl, Jakob J. (Inventor)
1991-01-01
A polarization filter can maximize the signal-to-noise ratio of a polarimetric SAR and help discriminate between targets or enhance image features, e.g., enhance contract between different types of target. The method disclosed is based on the Stokes matrix/Stokes vector representation, so the targets of interest can be extended targets, and the method can also be applied to the case of bistatic polarimetric radars.
Directory of Open Access Journals (Sweden)
Onur Jane
2016-01-01
Full Text Available Digital watermarking has been one of the focal points of research interests in order to provide multimedia security in the last decade. Watermark data, belonging to the user, are embedded on an original work such as text, audio, image, and video and thus, product ownership can be proved. Various robust watermarking algorithms have been developed in order to extract/detect the watermark against such attacks. Although watermarking algorithms in the transform domain differ from others by different combinations of transform techniques, it is difficult to decide on an algorithm for a specific application. Therefore, instead of developing a new watermarking algorithm with different combinations of transform techniques, we propose a novel and effective watermark extraction and detection method by pre-filtering, namely Adaptive Unsharp Masking (AUM. In spite of the fact that Unsharp Masking (UM based pre-filtering is used for watermark extraction/detection in the literature by causing the details of the watermarked image become more manifest, effectiveness of UM may decrease in some cases of attacks. In this study, AUM has been proposed for pre-filtering as a solution to the disadvantages of UM. Experimental results show that AUM performs better up to 11\\% in objective quality metrics than that of the results when pre-filtering is not used. Moreover; AUM proposed for pre-filtering in the transform domain image watermarking is as effective as that of used in image enhancement and can be applied in an algorithm-independent way for pre-filtering in transform domain image watermarking.
Identification of shear buildings using an instrumental variable method and linear integral filters
Concha, Antonio; Garrido, Rubén; Alvarez-Icaza, Luis
2016-12-01
This paper develops a method for estimating the parameters of a seismically excited building. Acceleration measurements of the ground and of the building floors, containing offsets and noise, are used for identification purposes. The proposed scheme estimates the complete model of the building if all the floors are equipped with accelerometers. Moreover, it also estimates a reduced model of the structure if only some floors are instrumented. The methodology is based on the combined use of the Instrumental Variable method and Linear Integral Filters. The Instrumental Variable method employs as instrument an auxiliary model of the structure, and it is able to directly identify the continuous-time structure model using discrete-time data without resorting on model transformations from continuous-time to discrete-time, and vice-versa. Using Linear Integral Filters allows obtaining a linear in the parameters expression that depends only on acceleration measurements suitable for parameter identification purposes. These filters eliminate measurement offsets and attenuate high-frequency measurement noise. The above features together with the use of the Instrumental variable method reduce the likelihood of biased parameter estimates. Experiments on a testbed employing a reduced-scale five-story structure allow comparing the results obtained using the Instrumental Variable method and those produced by the standard Least Squares method.
Voxel-Based Spatial Filtering Method for Canopy Height Retrieval from Airborne Single-Photon Lidar
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Hao Tang
2016-09-01
Full Text Available Airborne single-photon lidar (SPL is a new technology that holds considerable potential for forest structure and carbon monitoring at large spatial scales because it acquires 3D measurements of vegetation faster and more efficiently than conventional lidar instruments. However, SPL instruments use green wavelength (532 nm lasers, which are sensitive to background solar noise, and therefore SPL point clouds require more elaborate noise filtering than other lidar instruments to determine canopy heights, particularly in daytime acquisitions. Histogram-based aggregation is a commonly used approach for removing noise from photon counting lidar data, but it reduces the resolution of the dataset. Here we present an alternate voxel-based spatial filtering method that filters noise points efficiently while largely preserving the spatial integrity of SPL data. We develop and test our algorithms on an experimental SPL dataset acquired over Garrett County in Maryland, USA. We then compare canopy attributes retrieved using our new algorithm with those obtained from the conventional histogram binning approach. Our results show that canopy heights derived using the new algorithm have a strong agreement with field-measured heights (r2 = 0.69, bias = 0.42 m, RMSE = 4.85 m and discrete return lidar heights (r2 = 0.94, bias = 1.07 m, RMSE = 2.42 m. Results are consistently better than height accuracies from the histogram method (field data: r2 = 0.59, bias = 0.00 m, RMSE = 6.25 m; DRL: r2 = 0.78, bias = −0.06 m and RMSE = 4.88 m. Furthermore, we find that the spatial-filtering method retains fine-scale canopy structure detail and has lower errors over steep slopes. We therefore believe that automated spatial filtering algorithms such as the one presented here can support large-scale, canopy structure mapping from airborne SPL data.
An EMI Filter Selection Method Based on Spectrum of Digital Periodic Signal
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Matjaz Segula
2006-03-01
Full Text Available This paper describes a new method for the selection of an appropriate signal lineElectromagnetic Interference (EMI filter. To date, EMI filter selection has been based onthe measurement of the radiation of the entire device. The new selection method based onthe signalÃ¢Â€Â™s Fast Fourier Transform (FFT measurement has proved to be efficient. The EMIfilter is optimized separately for each line. The method described in this paper involving aCentral Processor Unit (CPU module demonstrates that the proposed FFT-based selectionmethod is better than the radiation-based one. The radiation level in the frequency range 30MHz to 1 GHz is lower for approximate 2 Ã¢Â€Â“ 6 dBÃŽÂ¼V/m.
Thruster fault diagnosis method based on Gaussian particle filter for autonomous underwater vehicles
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Yu-shan Sun
2016-05-01
Full Text Available Autonomous Underwater Vehicles (AUVs generally work in complex marine environments. Any fault in AUVs may cause significant losses. Thus, system reliability and automatic fault diagnosis are important. To address the actuator failure of AUVs, a fault diagnosis method based on the Gaussian particle filter is proposed in this study. Six free-space motion equation mathematical models are established in accordance with the actuator configuration of AUVs. The value of the control (moment loss parameter is adopted on the basis of these models to represent underwater vehicle malfunction, and an actuator failure model is established. An improved Gaussian particle filtering algorithm is proposed and is used to estimate the AUV failure model and motion state. Bayes algorithm is employed to perform robot fault detection. The sliding window method is adopted for fault magnitude estimation. The feasibility and validity of the proposed method are verified through simulation experiments and experimental data.
A second-order numerical method for elliptic equations with singular sources using local filter
Institute of Scientific and Technical Information of China (English)
Jiang Yongsong; Fang Le; Jing Xiaodong; Sun Xiaofeng; Francis Leboeuf
2013-01-01
The presence of Dirac delta function in differential equation can lead to a discontinuity, which may degrade the accuracy of related numerical methods. To improve the accuracy, a second-order numerical method for elliptic equations with singular sources is introduced by employing a local kernel filter. In this method, the discontinuous equation is convoluted with the kernel function to obtain a more regular one. Then the original equation is replaced by this filtered equation around the singular points, to obtain discrete numerical form. The unchanged equations at the other points are discretized by using a central difference scheme. 1D and 2D examples are carried out to validate the correctness and accuracy of the present method. The results show that a second-order of accu-racy can be obtained in the filtering framework with an appropriate integration rule. Furthermore, the present method does not need any jump condition, and also has extremely simple form that can be easily extended to high dimensional cases and complex geometry.
Second Order Low-Pass and High-Pass Filter Designs Using Method of Synthetic Immitance Elements
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Pavel Brandstetter
2013-01-01
Full Text Available The paper briefly describes the basics of frequency filter design method using synthetic immittance elements with current conveyors. An introduction of the paper explains the advantages and also disadvantages of using this method. Other chapters briefly introduce a design process of simple second order low-pass and high-pass filter. A theory of current conveyors is discussed too, because they are the basic building blocs of proposed synthetic element and also active frequency filters. Finally, the particular solutions of low-pass and high-pass filters are given and verified by OrCAD PSpice simulations.
Comparison of parabolic filtration methods for 3D filtered back projection in pulsed EPR imaging.
Qiao, Zhiwei; Redler, Gage; Epel, Boris; Halpern, Howard J
2014-11-01
Pulse electron paramagnetic resonance imaging (Pulse EPRI) is a robust method for noninvasively measuring local oxygen concentrations in vivo. For 3D tomographic EPRI, the most commonly used reconstruction algorithm is filtered back projection (FBP), in which the parabolic filtration process strongly influences image quality. In this work, we designed and compared 7 parabolic filtration methods to reconstruct both simulated and real phantoms. To evaluate these methods, we designed 3 error criteria and 1 spatial resolution criterion. It was determined that the 2 point derivative filtration method and the two-ramp-filter method have unavoidable negative effects resulting in diminished spatial resolution and increased artifacts respectively. For the noiseless phantom the rectangular-window parabolic filtration method and sinc-window parabolic filtration method were found to be optimal, providing high spatial resolution and small errors. In the presence of noise, the 3 point derivative method and Hamming-window parabolic filtration method resulted in the best compromise between low image noise and high spatial resolution. The 3 point derivative method is faster than Hamming-window parabolic filtration method, so we conclude that the 3 point derivative method is optimal for 3D FBP. Copyright © 2014. Published by Elsevier Inc.
An R-peak detection method that uses an SVD filter and a search back system.
Jung, Woo-Hyuk; Lee, Sang-Goog
2012-12-01
In this paper, we present a method for detecting the R-peak of an ECG signal by using an singular value decomposition (SVD) filter and a search back system. The ECG signal was detected in two phases: the pre-processing phase and the decision phase. The pre-processing phase consisted of the stages for the SVD filter, Butterworth High Pass Filter (HPF), moving average (MA), and squaring, whereas the decision phase consisted of a single stage that detected the R-peak. In the pre-processing phase, the SVD filter removed noise while the Butterworth HPF eliminated baseline wander. The MA removed the remaining noise of the signal that had gone through the SVD filter to make the signal smooth, and squaring played a role in strengthening the signal. In the decision phase, the threshold was used to set the interval before detecting the R-peak. When the latest R-R interval (RRI), suggested by Hamilton et al., was greater than 150% of the previous RRI, the method of detecting the R-peak in such an interval was modified to be 150% or greater than the smallest interval of the two most latest RRIs. When the modified search back system was used, the error rate of the peak detection decreased to 0.29%, compared to 1.34% when the modified search back system was not used. Consequently, the sensitivity was 99.47%, the positive predictivity was 99.47%, and the detection error was 1.05%. Furthermore, the quality of the signal in data with a substantial amount of noise was improved, and thus, the R-peak was detected effectively. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Malinowski Marcin
2015-02-01
Full Text Available In navigation practice, there are various navigational architecture and integration strategies of measuring instruments that affect the choice of the Kalman filtering algorithm. The analysis of different methods of Kalman filtration and associated smoothers applied in object tracing was made on the grounds of simulation tests of algorithms designed and presented in this paper. EKF (Extended Kalman Filter filter based on approximation with (jacobians partial derivations and derivative-free filters like UKF (Unscented Kalman Filter and CDKF (Central Difference Kalman Filter were implemented in comparison. For each method of filtration, appropriate smoothers EKS (Extended Kalman Smoother, UKS (Unscented Kalman Smoother and CDKS (Central Difference Kalman Smoother were presented as well. Algorithms performance is discussed on the theoretical base and simulation results of two cases are presented.
DEFF Research Database (Denmark)
Wu, Weimin; Lin, Zhe; Sun, Yunjie
2013-01-01
Grid-tied inverters have been widely used to inject the renewable energies into the distributed power generation systems. However, a large variation of the grid impedance challenges the stability of the high-order power filter based grid-tied inverter. Many passive and active damping methods have...... been proposed to overcome this issue. Recently, a composite passive damping method for a high-order power filter based grid-tied inverter with an RC parallel damper and an RL series damper was presented to eliminate this problem, but at the cost of more material and power losses. In this paper...
Multifractal filtering method for extraction of ocean eddies from remotely sensed imagery
Institute of Scientific and Technical Information of China (English)
GE Yong; DU Yunyan; CHENG Qiuming; LI Ce
2006-01-01
Traditional methods of extracting the ocean wave eddy information from remotely sensed imagery mainly use the edge detection technology such as Canny and Hough operators. However, due to the complexities of ocean eddies and image itself, it is sometimes difficult to successfully detect ocean eddies using these methods. A multifractal filtering technology is proposed for extraction of ocean eddies and demonstrated using NASA MODIS,SeaWiFS and NOAA satellite data set in the typical area, such as ocean west boundary current. Results showed that the new method has a superior performance over the traditional methods.
Energy Technology Data Exchange (ETDEWEB)
Ray, Jaideep; Lefantzi, Sophia; Najm, Habib N.; Kennedy, Christopher A.
2006-01-01
Block-structured adaptively refined meshes (SAMR) strive for efficient resolution of partial differential equations (PDEs) solved on large computational domains by clustering mesh points only where required by large gradients. Previous work has indicated that fourth-order convergence can be achieved on such meshes by using a suitable combination of high-order discretizations, interpolations, and filters and can deliver significant computational savings over conventional second-order methods at engineering error tolerances. In this paper, we explore the interactions between the errors introduced by discretizations, interpolations and filters. We develop general expressions for high-order discretizations, interpolations, and filters, in multiple dimensions, using a Fourier approach, facilitating the high-order SAMR implementation. We derive a formulation for the necessary interpolation order for given discretization and derivative orders. We also illustrate this order relationship empirically using one and two-dimensional model problems on refined meshes. We study the observed increase in accuracy with increasing interpolation order. We also examine the empirically observed order of convergence, as the effective resolution of the mesh is increased by successively adding levels of refinement, with different orders of discretization, interpolation, or filtering.
Peng, Fulai; Liu, Hongyun; Wang, Weidong
2015-10-01
A photoplethysmographic (PPG) signal can provide very useful information about a subject's cardiovascular status. Motion artifacts (MAs), which usually deteriorate the waveform of a PPG signal, severely obstruct its applications in the clinical diagnosis and healthcare area. To reduce the MAs from a PPG signal, in the present study we present a comb filter based signal processing method. Firstly, wavelet de-noising was implemented to preliminarily suppress a part of the MAs. Then, the PPG signal in the time domain was transformed into the frequency domain by a fast Fourier transform (FFT). Thirdly, the PPG signal period was estimated from the frequency domain by tracking the fundamental frequency peak of the PPG signal. Lastly, the MAs were removed by the comb filter which was designed based on the obtained PPG signal period. Experiments with synthetic and real-world datasets were implemented to validate the performance of the method. Results show that the proposed method can effectively restore the PPG signals from the MA corrupted signals. Also, the accuracy of blood oxygen saturation (SpO2), calculated from red and infrared PPG signals, was significantly improved after the MA reduction by the proposed method. Our study demonstrates that the comb filter can effectively reduce the MAs from a PPG signal provided that the PPG signal period is obtained.
Spatial and Transform Domain Filtering Method for Image De-noising: A Review
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Vandana Roy
2013-09-01
Full Text Available Present investigation reveals the quantum of work carried in the filtering methods for image de-noising. An image is often gets corrupted by various noises that are visible or invisible while being gathered, coded, acquired and transmitted. Noise influences various process parameters that may cause a quality problem for further image processing. De-noising of natural images is appears to be very simple however when considered under practical situations becomes complex. It has been cited by various author that parameter such as type and quantum of noise, image etc. through single algorithm or approach becomes cumbersome when results are optimized. In order to improve the quality of an image noise must be removed when the image is pre-processed and the important signal features like edge details should be retained as much as possible. The search on efficient image de-noising methods is still a valid challenge at the crossing of functional analysis and statistics. This paper reviews significant de-noising methods (spatial and transform domain method and their salient features and applications. One filter in each category has been taken in consideration to understand the characteristics of both spatial and transform domain filters.
Directory of Open Access Journals (Sweden)
Jiaoying Jin
2013-01-01
extraction of vascular trees from 2D medical images is presented, which combines Hessian-based multiscale filtering and a modified level set method. In the proposed algorithm, the morphological top-hat transformation is firstly adopted to attenuate background. Then Hessian-based multiscale filtering is used to enhance vascular structures by combining Hessian matrix with Gaussian convolution to tune the filtering response to the specific scales. Because Gaussian convolution tends to blur vessel boundaries, which makes scale selection inaccurate, an improved level set method is finally proposed to extract vascular structures by introducing an external constrained term related to the standard deviation of Gaussian function into the traditional level set. Our approach was tested on synthetic images with vascular-like structures and 2D slices extracted from real 3D abdomen magnetic resonance angiography (MRA images along the coronal plane. The segmentation rates for synthetic images are above 95%. The results for MRA images demonstrate that the proposed method can extract most of the vascular structures successfully and accurately in visualization. Therefore, the proposed method is effective for the vascular tree extraction in medical images.
Ge, Shuang-Chao; Deng, Ming; Chen, Kai; Li, Bin; Li, Yuan
2016-12-01
Time-domain induced polarization (TDIP) measurement is seriously affected by power line interference and other field noise. Moreover, existing TDIP instruments generally output only the apparent chargeability, without providing complete secondary field information. To increase the robustness of TDIP method against interference and obtain more detailed secondary field information, an improved dataprocessing algorithm is proposed here. This method includes an efficient digital notch filter which can effectively eliminate all the main components of the power line interference. Hardware model of this filter was constructed and Vhsic Hardware Description Language code for it was generated using Digital Signal Processor Builder. In addition, a time-location method was proposed to extract secondary field information in case of unexpected data loss or failure of the synchronous technologies. Finally, the validity and accuracy of the method and the notch filter were verified by using the Cole-Cole model implemented by SIMULINK software. Moreover, indoor and field tests confirmed the application effect of the algorithm in the fieldwork.
A New Method to Determine the Temperature of CMEs Using a Coronagraph Filter System
Cho, Kyuhyoun; Lim, Eun-kyung; Cho, Kyung-suk; Bong, Su-Chan; Yang, Heesu
2016-01-01
The coronagraph is an instrument enables the investigation of faint features in the vicinity of the Sun, particularly coronal mass ejections (CMEs). So far coronagraphic observations have been mainly used to determine the geometric and kinematic parameters of CMEs. Here, we introduce a new method for the determination of CME temperature using a two filter (4025 A and 3934 A) coronagraph system. The thermal motion of free electrons in CMEs broadens the absorption lines in the optical spectra that are produced by the Thomson scattering of visible light originating in the photosphere, which affects the intensity ratio at two different wavelengths. Thus the CME temperature can be inferred from the intensity ratio measured by the two filter coronagraph system. We demonstrate the method by invoking the graduated cylindrical shell (GCS) model for the 3 dimensional CME density distribution and discuss its significance.
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Lianhui Li
2015-12-01
Full Text Available Medium-and-long-term load forecasting plays an important role in energy policy implementation and electric department investment decision. Aiming to improve the robustness and accuracy of annual electric load forecasting, a robust weighted combination load forecasting method based on forecast model filtering and adaptive variable weight determination is proposed. Similar years of selection is carried out based on the similarity between the history year and the forecast year. The forecast models are filtered to select the better ones according to their comprehensive validity degrees. To determine the adaptive variable weight of the selected forecast models, the disturbance variable is introduced into Immune Algorithm-Particle Swarm Optimization (IA-PSO and the adaptive adjustable strategy of particle search speed is established. Based on the forecast model weight determined by improved IA-PSO, the weighted combination forecast of annual electric load is obtained. The given case study illustrates the correctness and feasibility of the proposed method.
The method of successive decrease and the harmonic wave filter for wave control in structures
Institute of Scientific and Technical Information of China (English)
王泉; 王大钧; A. Y. T. Leung
1996-01-01
Attempt is made to solve some of the existing problems due to the application of themodal control method. A wave control method--the method of successive decrease is set up at first, which isaimed at one harmonic wave. Then, a new design method in wave control is proposed based on the above method. The problem of control spillover is analyzed and the concept of harmonic wave filter is introduced.As an example, the problem of the control of structures with closely spaced natural frequencies is treated by both the method of modal control and the method of successive decrease. The numerical results show that the method of successive decrease is more effective than the method of modal control for this problem.
Choosing Wavelet Methods, Filters, and Lengths for Functional Brain Network Construction.
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Zitong Zhang
Full Text Available Wavelet methods are widely used to decompose fMRI, EEG, or MEG signals into time series representing neurophysiological activity in fixed frequency bands. Using these time series, one can estimate frequency-band specific functional connectivity between sensors or regions of interest, and thereby construct functional brain networks that can be examined from a graph theoretic perspective. Despite their common use, however, practical guidelines for the choice of wavelet method, filter, and length have remained largely undelineated. Here, we explicitly explore the effects of wavelet method (MODWT vs. DWT, wavelet filter (Daubechies Extremal Phase, Daubechies Least Asymmetric, and Coiflet families, and wavelet length (2 to 24-each essential parameters in wavelet-based methods-on the estimated values of graph metrics and in their sensitivity to alterations in psychiatric disease. We observe that the MODWT method produces less variable estimates than the DWT method. We also observe that the length of the wavelet filter chosen has a greater impact on the estimated values of graph metrics than the type of wavelet chosen. Furthermore, wavelet length impacts the sensitivity of the method to detect differences between health and disease and tunes classification accuracy. Collectively, our results suggest that the choice of wavelet method and length significantly alters the reliability and sensitivity of these methods in estimating values of metrics drawn from graph theory. They furthermore demonstrate the importance of reporting the choices utilized in neuroimaging studies and support the utility of exploring wavelet parameters to maximize classification accuracy in the development of biomarkers of psychiatric disease and neurological disorders.
Design method of dichroic filter using color appearance model in LCD projection systems
Kim, Jee-Hong
1998-11-01
A new design method using a color appearance model is proposed for the dichroic filters in LCD projection systems. The dichroic filters used for color separation/composition play a dominant role in the performance of color reproduction so that its spectral transmittance should be designed to have optimized color performance. In the proposed method, a reproducible color gamut in the 3D color space is used as a performance index, and we find the optimal half-power wavelengths of dichroic filters, which are applicable to the development of LCD projection TV systems. Considering diverse viewing conditions with moderate ambient light, the design parameters are optimized by maximizing the volume of the color gamut in an apparent color space for each condition. Here, the RLAB color space developed by Fairchild is used as a color appearance model and the white balancing method is applied to restore the designate color temperature of peak white. The optimal wavelengths are compared with the design based on the CIELAB color space without considering nonstandard viewing conditions, and both results do not show as much difference as expected due to the white balance.
Energy Technology Data Exchange (ETDEWEB)
McKenney, Sarah E.; Nosratieh, Anita; Gelskey, Dale; Yang Kai; Huang Shinying; Chen Lin; Boone, John M. [Department of Radiology, University of California, Davis Medical Center, Rm. 0505, ACC Ellison Bldg., 4860 Y St., Sacramento, California 95817 (United States) and Department of Biomedical Engineering, University of California, Davis, Rm. 2303, GBSF, 451 E. Health Science Dr., Davis, California 95616 (United States); Diagnostic Imaging Specialists Corporation (DISC), 163 St. Malo Street, St. Malo, Manitoba R0A 1T0 (Canada); Department of Radiology, University of California, Davis Medical Center, Rm. 0505, ACC Ellison Bldg., 4860 Y St., Sacramento, California 95817 (United States); Department of Radiology, University of California, Davis Medical Center, Rm. 0505, ACC Ellison Bldg., 4860 Y St., Sacramento, California 95817 (United States) and Department of Biomedical Engineering, University of California, Davis, Rm. 2303, GBSF, 451 E. Health Science Dr., Davis, California 95616 (United States)
2011-03-15
Purpose: Beam-shaping or ''bow tie'' (BT) filters are used to spatially modulate the x-ray beam in a CT scanner, but the conventional method of step-and-shoot measurement to characterize a beam's profile is tedious and time-consuming. The theory for characterization of bow tie relative attenuation (COBRA) method, which relies on a real-time dosimeter to address the issues of conventional measurement techniques, was previously demonstrated using computer simulations. In this study, the feasibility of the COBRA theory is further validated experimentally through the employment of a prototype real-time radiation meter and a known BT filter. Methods: The COBRA method consisted of four basic steps: (1) The probe was placed at the edge of a scanner's field of view; (2) a real-time signal train was collected as the scanner's gantry rotated with the x-ray beam on; (3) the signal train, without a BT filter, was modeled using peak values measured in the signal train of step 2; and (4) the relative attenuation of the BT filter was estimated from filtered and unfiltered data sets. The prototype probe was first verified to have an isotropic and linear response to incident x-rays. The COBRA method was then tested on a dedicated breast CT scanner with a custom-designed BT filter and compared to the conventional step-and-shoot characterization of the BT filter. Using basis decomposition of dual energy signal data, the thickness of the filter was estimated and compared to the BT filter's manufacturing specifications. The COBRA method was also demonstrated with a clinical whole body CT scanner using the body BT filter. The relative attenuation was calculated at four discrete x-ray tube potentials and used to estimate the thickness of the BT filter. Results: The prototype probe was found to have a linear and isotropic response to x-rays. The relative attenuation produced from the COBRA method fell within the error of the relative attenuation
A New Synchronous Reference Frame-Based Method for Single-Phase Shunt Active Power Filters
DEFF Research Database (Denmark)
Monfared, Mohammad; Golestan, Saeed; Guerrero, Josep M.
2013-01-01
This paper deals with the design of a novel method in the synchronous reference frame (SRF) to extract the reference compensating current for single-phase shunt active power filters (APFs). Unlike previous works in the SRF, the proposed method has an innovative feature that it does not need...... the fictitious current signal. Frequency-independent operation, accurate reference current extraction and relatively fast transient response are other key features of the presented strategy. The effectiveness of the proposed method is investigated by means of detailed mathematical analysis. The results confirm...
A method for retrieving clouds with satellite infrared radiances using the particle filter
Xu, Dongmei; Auligné, Thomas; Descombes, Gaël; Snyder, Chris
2016-11-01
Ensemble-based techniques have been widely utilized in estimating uncertainties in various problems of interest in geophysical applications. A new cloud retrieval method is proposed based on the particle filter (PF) by using ensembles of cloud information in the framework of Gridpoint Statistical Interpolation (GSI) system. The PF cloud retrieval method is compared with the Multivariate Minimum Residual (MMR) method that was previously established and verified. Cloud retrieval experiments involving a variety of cloudy types are conducted with the PF and MMR methods with measurements of infrared radiances on multi-sensors onboard both geostationary and polar satellites, respectively. It is found that the retrieved cloud masks with both methods are consistent with other independent cloud products. MMR is prone to producing ambiguous small-fraction clouds, while PF detects clearer cloud signals, yielding closer heights of cloud top and cloud base to other references. More collections of small-fraction particles are able to effectively estimate the semi-transparent high clouds. It is found that radiances with high spectral resolutions contribute to quantitative cloud top and cloud base retrievals. In addition, a different way of resolving the filtering problem over each model grid is tested to better aggregate the weights with all available sensors considered, which is proven to be less constrained by the ordering of sensors. Compared to the MMR method, the PF method is overall more computationally efficient, and the cost of the model grid-based PF method scales more directly with the number of computing nodes.
QSAR study on the non-monotonic dose-response curve of PCBs in chicken embryo hepatocyte bioassay
Institute of Scientific and Technical Information of China (English)
MU YunSong; ZHANG AiQian; GAO ChangAn; PENG SuFen; WANG LianSheng
2009-01-01
Endocrine disrupting chemicals (EDCs) in the natural environment exhibit a unique non-monotonic dose-response curve and it is impossible to select one simple index to characterize the bilogogical activity of these compounds. Quantitative structure-activity relationship (QSAR) study on non-monotonic dose-response curve has become a real challenge presently. In order to explore the possible mechanism for the non-monotonic dose-response curve of polychlorinated biphenyls con-geners (PCBs) in chicken embryo hepatocyte bioassay, AM1 method of ChemOffice was adopted to calculate necessary structure descriptors for PCBs, while the interactions between PCBs and simulated AhR ligand binding domain (LBD) were analyzed by using FlexX in SYBYL7.0. Different binding modes for PCBs have been distinguished not only from aligned conformation but also from free binding energy. Some QSAR models were established separately for both low and high doses ranges, revealing that receptor binding may predominate in the interference of the physiological function of cytochrome P4501A-P4501A in the low doses range. But with the higher doses range, the EROD suppression might he related to acute toxicity owing to molecular polarity or distribution of charges and consequently damage structure and function of chicken embryo hepatocyte.
QSAR study on the non-monotonic dose-response curve of PCBs in chicken embryo hepatocyte bioassay
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Endocrine disrupting chemicals (EDCs) in the natural environment exhibit a unique non-monotonic dose-response curve and it is impossible to select one simple index to characterize the bilogogical activity of these compounds. Quantitative structure-activity relationship (QSAR) study on non-monotonic dose-response curve has become a real challenge presently. In order to explore the possible mechanism for the non-monotonic dose-response curve of polychlorinated biphenyls congeners (PCBs) in chicken embryo hepatocyte bioassay, AM1 method of ChemOffice was adopted to calculate necessary structure descriptors for PCBs, while the interactions between PCBs and simulated AhR ligand binding domain (LBD) were analyzed by using FlexX in SYBYL7.0. Different binding modes for PCBs have been distinguished not only from aligned conformation but also from free binding energy. Some QSAR models were established separately for both low and high doses ranges, revealing that receptor binding may predominate in the interference of the physiological function of cytochrome P4501A-P4501A in the low doses range. But with the higher doses range, the EROD suppression might be related to acute toxicity owing to molecular polarity or distribution of charges and consequently damage structure and function of chicken embryo hepatocyte.
Two-dimensional nonlinear geophysical data filtering using the multidimensional EEMD method
Chen, Chih-Sung; Jeng, Yih
2014-12-01
A variety of two-dimensional (2D) empirical mode decomposition (EMD) methods have been proposed in the last decade. Furthermore, the multidimensional EMD algorithm and its parallel class, multivariate EMD (MEMD), are available in recent years. From those achievements, it is possible to design an efficient 2D nonlinear filter for geophysical data processing. We introduce a robust 2D nonlinear filter which can be applied to enhance the signal of 2D geophysical data or to highlight the feature component on an image. We did this by replacing the conventionally used smooth interpolation in the ensemble empirical mode decomposition (EEMD) algorithm with a piecewise interpolation method. The one-dimensional (1D) EEMD procedures were consecutively performed in all directions, and then the comparable minimal scale combination technique was applied to the decomposed components. The theoretical derivation, model simulation, and real data applications are demonstrated in this paper. The proposed filtering method is effective in improving the image resolution by suppressing the random noise added in the simulation example and strong low frequency track corrugation noise bands with background noise in the field example. Furthermore, the algorithm can be easily extended to higher dimensions by repeating the same procedure in the succeeding dimension. To evaluate the proposed method, one data set is processed separately by using the enhanced analytic signal method and the multivariate EMD (MEMD) algorithm, and the results from these two methods are compared with that of the proposed method. A general equation for generating three-dimensional (3D) EEMD components based on the comparable minimal scale combination principle is derived for further applications.
An object tracking method based on guided filter for night fusion image
Qian, Xiaoyan; Wang, Yuedong; Han, Lei
2016-01-01
Online object tracking is a challenging problem as it entails learning an effective model to account for appearance change caused by intrinsic and extrinsic factors. In this paper, we propose a novel online object tracking with guided image filter for accurate and robust night fusion image tracking. Firstly, frame difference is applied to produce the coarse target, which helps to generate observation models. Under the restriction of these models and local source image, guided filter generates sufficient and accurate foreground target. Then accurate boundaries of the target can be extracted from detection results. Finally timely updating for observation models help to avoid tracking shift. Both qualitative and quantitative evaluations on challenging image sequences demonstrate that the proposed tracking algorithm performs favorably against several state-of-art methods.
A controller design method for 3 phase 4 wire grid connected VSI with LCL filter
Indian Academy of Sciences (India)
Anirban Ghoshal; Vinod John
2015-08-01
Closed loop control of a grid connected VSI requires line current control and dc bus voltage control. The closed loop system comprising PR current controller and grid connected VSI with LCL filter is a higher order system. Closed loop control gain expressions are therefore difficult to obtain directly for such systems. In this work a simplified approach has been adopted to find current and voltage controller gain expressions for a 3 phase 4 wire grid connected VSI with LCL filter. The closed loop system considered here utilises PR current controller in natural reference frame and PI controller for dc bus voltage control. Asymptotic frequency response plot and gain bandwidth requirements of the system have been used for current control and voltage controller design. A simplified lower order model, derived for closed loop current control, is used for the dc bus voltage controller design. The adopted design method has been verified through experiments by comparison of the time domain response.
Directory of Open Access Journals (Sweden)
Shkvarko Yuriy
2006-01-01
Full Text Available We address a new approach to solve the ill-posed nonlinear inverse problem of high-resolution numerical reconstruction of the spatial spectrum pattern (SSP of the backscattered wavefield sources distributed over the remotely sensed scene. An array or synthesized array radar (SAR that employs digital data signal processing is considered. By exploiting the idea of combining the statistical minimum risk estimation paradigm with numerical descriptive regularization techniques, we address a new fused statistical descriptive regularization (SDR strategy for enhanced radar imaging. Pursuing such an approach, we establish a family of the SDR-related SSP estimators, that encompass a manifold of existing beamforming techniques ranging from traditional matched filter to robust and adaptive spatial filtering, and minimum variance methods.
Packet Format Design and Decision Directed Tracking Methods for Filter Bank Multicarrier Systems
Amini, Peiman; Farhang-Boroujeny, Behrouz
2010-12-01
Packetized data transmission is commonly used in wireless communication systems. Each packet starts with a preamble which is used to synchronize the receiver with carrier frequency of the incoming signal, to find a good timing phase, and to identify the channel impulse response or to adjust a set of channel equalizer parameters. In this paper, following the same philosophy, we develop a packet format for multicarrier systems that operate based on filter banks, filter bank multicarrier (FBMC) systems. The related algorithms for carrier frequency and timing recovery as well as channel identification/equalizer adjustment and methods for carrier and timing tracking loops are proposed. The proposed ideas are evaluated and their satisfactory performance are presented through computer simulations.
Packet Format Design and Decision Directed Tracking Methods for Filter Bank Multicarrier Systems
Directory of Open Access Journals (Sweden)
Amini Peiman
2010-01-01
Full Text Available Packetized data transmission is commonly used in wireless communication systems. Each packet starts with a preamble which is used to synchronize the receiver with carrier frequency of the incoming signal, to find a good timing phase, and to identify the channel impulse response or to adjust a set of channel equalizer parameters. In this paper, following the same philosophy, we develop a packet format for multicarrier systems that operate based on filter banks, filter bank multicarrier (FBMC systems. The related algorithms for carrier frequency and timing recovery as well as channel identification/equalizer adjustment and methods for carrier and timing tracking loops are proposed. The proposed ideas are evaluated and their satisfactory performance are presented through computer simulations.
Nonmonotonic quantum-to-classical transition in multiparticle interference
DEFF Research Database (Denmark)
Ra, Young-Sik; Tichy, Malte; Lim, Hyang-Tag
2013-01-01
Quantum-mechanical wave–particle duality implies that probability distributions for granular detection events exhibit wave-like interference. On the single-particle level, this leads to self-interference—e.g., on transit across a double slit—for photons as well as for large, massive particles...... that interference fades away monotonically with increasing distinguishability—in accord with available experimental evidence on the single- and on the many-particle level. Here, we demonstrate experimentally and theoretically that such monotonicity of the quantum-to-classical transition is the exception rather than...... the rule whenever more than two particles interfere. As the distinguishability of the particles is continuously increased, different numbers of particles effectively interfere, which leads to interference signals that are, in general, nonmonotonic functions of the distinguishability of the particles...
Chaos in neural networks with a nonmonotonic transfer function
Caroppo, D; Nardulli, Giuseppe; Stramaglia, S
1999-01-01
Time evolution of diluted neural networks with a nonmonotonic transfer function is analitically described by flow equations for macroscopic variables. The macroscopic dynamics shows a rich variety of behaviours: fixed-point, periodicity and chaos. We examine in detail the structure of the strange attractor and in particular we study the main features of the stable and unstable manifolds, the hyperbolicity of the attractor and the existence of homoclinic intersections. We also discuss the problem of the robustness of the chaos and we prove that in the present model chaotic behaviour is fragile (chaotic regions are densely intercalated with periodicity windows), according to a recently discussed conjecture. Finally we perform an analysis of the microscopic behaviour and in particular we examine the occurrence of damage spreading by studying the time evolution of two almost identical initial configurations. We show that for any choice of the parameters the two initial states remain microscopically distinct.
Multitracer and filter-separated half-cell method for measuring solute diffusion in undisturbed soil
DEFF Research Database (Denmark)
Lægdsmand, Mette; Møldrup, Per; Schjønning, Per
2010-01-01
Solute diffusion controls important processes in soils: plant uptake of nutrients, sorption-desorption processes, degradation of organic matter, and leaching of radionuclides through clay barriers. We developed a new method for measuring the solute diffusivity (solute diffusion coefficient...... in the soil relative to water) in intact soil samples (the Multiple Tracer, Filter Separated half-cell method using a Dynamic Model for parameter estimation [MT-FS-DM]). The MT-FS-DM method consists of half-cell diffusion of two pairs of counterdiffusing anionic tracers and a parameter estimation scheme...... that the MT-FS-DM method provided reliable results. We compared diffusivities measured on a sandy loam soil using the MT-FS-DM method with diffusivities from six sandy loam test soils from the literature. The new method can be used to estimate solute diffusivity in intact structured soil and provides a more...
Particle filtering methods for georeferencing panoramic image sequence in complex urban scenes
Ji, Shunping; Shi, Yun; Shan, Jie; Shao, Xiaowei; Shi, Zhongchao; Yuan, Xiuxiao; Yang, Peng; Wu, Wenbin; Tang, Huajun; Shibasaki, Ryosuke
2015-07-01
Georeferencing image sequences is critical for mobile mapping systems. Traditional methods such as bundle adjustment need adequate and well-distributed ground control points (GCP) when accurate GPS data are not available in complex urban scenes. For applications of large areas, automatic extraction of GCPs by matching vehicle-born image sequences with geo-referenced ortho-images will be a better choice than intensive GCP collection with field surveying. However, such image matching generated GCP's are highly noisy, especially in complex urban street environments due to shadows, occlusions and moving objects in the ortho images. This study presents a probabilistic solution that integrates matching and localization under one framework. First, a probabilistic and global localization model is formulated based on the Bayes' rules and Markov chain. Unlike many conventional methods, our model can accommodate non-Gaussian observation. In the next step, a particle filtering method is applied to determine this model under highly noisy GCP's. Owing to the multiple hypotheses tracking represented by diverse particles, the method can balance the strength of geometric and radiometric constraints, i.e., drifted motion models and noisy GCP's, and guarantee an approximately optimal trajectory. Carried out tests are with thousands of mobile panoramic images and aerial ortho-images. Comparing with the conventional extended Kalman filtering and a global registration method, the proposed approach can succeed even under more than 80% gross errors in GCP's and reach a good accuracy equivalent to the traditional bundle adjustment with dense and precise control.
eTACTS: a method for dynamically filtering clinical trial search results.
Miotto, Riccardo; Jiang, Silis; Weng, Chunhua
2013-12-01
Information overload is a significant problem facing online clinical trial searchers. We present eTACTS, a novel interactive retrieval framework using common eligibility tags to dynamically filter clinical trial search results. eTACTS mines frequent eligibility tags from free-text clinical trial eligibility criteria and uses these tags for trial indexing. After an initial search, eTACTS presents to the user a tag cloud representing the current results. When the user selects a tag, eTACTS retains only those trials containing that tag in their eligibility criteria and generates a new cloud based on tag frequency and co-occurrences in the remaining trials. The user can then select a new tag or unselect a previous tag. The process iterates until a manageable number of trials is returned. We evaluated eTACTS in terms of filtering efficiency, diversity of the search results, and user eligibility to the filtered trials using both qualitative and quantitative methods. eTACTS (1) rapidly reduced search results from over a thousand trials to ten; (2) highlighted trials that are generally not top-ranked by conventional search engines; and (3) retrieved a greater number of suitable trials than existing search engines. eTACTS enables intuitive clinical trial searches by indexing eligibility criteria with effective tags. User evaluation was limited to one case study and a small group of evaluators due to the long duration of the experiment. Although a larger-scale evaluation could be conducted, this feasibility study demonstrated significant advantages of eTACTS over existing clinical trial search engines. A dynamic eligibility tag cloud can potentially enhance state-of-the-art clinical trial search engines by allowing intuitive and efficient filtering of the search result space. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.
Wang, Zhenwu; Hut, Rolf; van de Giesen, Nick
2017-04-01
Particle filtering is a nonlinear and non-Gaussian dynamical filtering system. It has found widespread applications in hydrological data assimilation. In order to solve the loss of particle diversity exiting in resampling process of particle filter, this research proposes an improved particle filter algorithm using genetic algorithm optimization and Gamma test. This method combines the genetic algorithm and Gamma test into the resampling procedure of particle filter to improve the adaptability and performance of particle filter in data assimilation. First, the particles are classified to three different groups based on resampling method. The particles with high weight values remain unchanged. Then genetic algorithm is used to cross and variate the rest of the particles. In the process of the optimization, the Gamma test method is applied for monitoring the quality of the new generated particles. When the gamma statistic stays stable, the algorithm will end the optimization and continue to perturb next observations in particle algorithm. The algorithm is illustrated for the three-dimensional Lorenz model and the much more complex 40-dimensional Lorenz model. The results demonstrate this method can keep the diversity of the particles and enhance the performance of the particle filter, leading to the promising conjecture that the method is applicable to realistic hydrological problems.
DEFF Research Database (Denmark)
Nadernejad, Ehsan; Sharifzadeh, Sara
2013-01-01
In this paper, a new pixon-based method is presented for image segmentation. In the proposed algorithm, bilateral filtering is used as a kernel function to form a pixonal image. Using this filter reduces the noise and smoothes the image slightly. By using this pixon-based method, the image over s...... the hierarchical clustering method (Fuzzy C-means algorithm). The experimental results show that the proposed pixon-based approach has a reduced computational load and a better accuracy compared to the other existing pixon-based image segmentation techniques.......In this paper, a new pixon-based method is presented for image segmentation. In the proposed algorithm, bilateral filtering is used as a kernel function to form a pixonal image. Using this filter reduces the noise and smoothes the image slightly. By using this pixon-based method, the image over...
Estimation of geosynchronous space objects using finite set statistics filtering methods
Gehly, Steve
The use of near Earth space has increased dramatically in the past few decades, and operational satellites are an integral part of modern society. The increased presence in space has led to an increase in the amount of orbital debris, which poses a growing threat to current and future space missions. Characterization of the debris environment is crucial to our continued use of high value orbit regimes such as the geosynchronous (GEO) belt. Objects in GEO pose unique challenges, by virtue of being densely spaced and tracked by a limited number of sensors in short observation windows. This research examines the use of a new class of multitarget filters to approach the problem of orbit determination for the large number of objects present. The filters make use of a recently developed mathematical toolbox derived from point process theory known as Finite Set Statistics (FISST). Details of implementing FISST-derived filters are discussed, and a qualitative and quantitative comparison between FISST and traditional multitarget estimators demonstrates the suitability of the new methods for space object estimation. Specific challenges in the areas of sensor allocation and initial orbit determination are addressed in the framework. The sensor allocation scheme makes use of information gain functionals as formulated for FISST to efficiently collect measurements on the full multitarget system. Results from a simulated network of three ground stations tracking a large catalog of geosynchronous objects demonstrate improved performance as compared to simpler, non-information theoretic tasking schemes. Further studies incorporate an initial orbit determination technique to initiate new tracks in the multitarget filter. Together with a sensor allocation scheme designed to search for new targets and maintain knowledge of the existing catalog, the method comprises a solution to the search-detect-track problem. Simulation results for a single sensor case show that the problem can be
An Effective Gap Filtering Method for Landsat ETM+ SLC-Off Data
Directory of Open Access Journals (Sweden)
Seulki Lee
2016-01-01
Full Text Available The Landsat 7 Enhanced Thematic Mapper Plus (ETM+ scan line corrector (SLC failed on 31 May 2003, causing the SLC to turn off. Many gap-filled products were developed and deployed to combat this situation. The majority of these products used a primary image taken by the SLC when functioning properly in an attempt to correct SLC-off images. However, temporal atmospheric elements could not be reliably reflected using a primary image, and therefore the corrected image was not viable for use by monitoring systems. To bypass this limitation, this study has developed the Gap Interpolation and Filtering (GIF method that relies on one-dimensional interpolation filtering to conveniently recover pixels within a single image at a high level of accuracy without borrowing from images acquired at a different time or by another sensor. The GIF method was compared to two other methods—Global Linear Histogram Match (GLHM, and the Local Linear Histogram Match (LLHM—both developed by National Aeronautics and Space Administration (NASA and United States Geological Survey (USGS to determine its accuracy. The GIF method accuracy was found superior in land, sea, and cloud imaging. In particular, its sea and cloud images returned Root Mean Square Error (RMSE values close to or less than 1. We expect the GIF method developed in this research to be of invaluable aid to monitoring systems that depend heavily on Landsat imagery.
A seismic interpolation and denoising method with curvelet transform matching filter
Yang, Hongyuan; Long, Yun; Lin, Jun; Zhang, Fengjiao; Chen, Zubin
2017-09-01
A new seismic interpolation and denoising method with a curvelet transform matching filter, employing the fast iterative shrinkage thresholding algorithm (FISTA), is proposed. The approach treats the matching filter, seismic interpolation, and denoising all as the same inverse problem using an inversion iteration algorithm. The curvelet transform has a high sparseness and is useful for separating signal from noise, meaning that it can accurately solve the matching problem using FISTA. When applying the new method to a synthetic noisy data sets and a data sets with missing traces, the optimum matching result is obtained, noise is greatly suppressed, missing seismic data are filled by interpolation, and the waveform is highly consistent. We then verified the method by applying it to real data, yielding satisfactory results. The results show that the method can reconstruct missing traces in the case of low SNR (signal-to-noise ratio). The above three problems can be simultaneously solved via FISTA algorithm, and it will not only increase the processing efficiency but also improve SNR of the seismic data.
Li, Zhong-xiao; Li, Zhen-chun
2016-09-01
The multichannel predictive deconvolution can be conducted in overlapping temporal and spatial data windows to solve the 2D predictive filter for multiple removal. Generally, the 2D predictive filter can better remove multiples at the cost of more computation time compared with the 1D predictive filter. In this paper we first use the cross-correlation strategy to determine the limited supporting region of filters where the coefficients play a major role for multiple removal in the filter coefficient space. To solve the 2D predictive filter the traditional multichannel predictive deconvolution uses the least squares (LS) algorithm, which requires primaries and multiples are orthogonal. To relax the orthogonality assumption the iterative reweighted least squares (IRLS) algorithm and the fast iterative shrinkage thresholding (FIST) algorithm have been used to solve the 2D predictive filter in the multichannel predictive deconvolution with the non-Gaussian maximization (L1 norm minimization) constraint of primaries. The FIST algorithm has been demonstrated as a faster alternative to the IRLS algorithm. In this paper we introduce the FIST algorithm to solve the filter coefficients in the limited supporting region of filters. Compared with the FIST based multichannel predictive deconvolution without the limited supporting region of filters the proposed method can reduce the computation burden effectively while achieving a similar accuracy. Additionally, the proposed method can better balance multiple removal and primary preservation than the traditional LS based multichannel predictive deconvolution and FIST based single channel predictive deconvolution. Synthetic and field data sets demonstrate the effectiveness of the proposed method.
Zhang, Liangjing; Dahle, Christoph; Neumayer, Karl-Hans; Dobslaw, Henryk; Flechtner, Frank; Thomas, Maik
2016-04-01
Terrestrial water storage (TWS) variations obtained from GRACE play an increasingly important role in various hydrological and hydro-meteorological applications. Since monthly-mean gravity fields are contaminated by errors caused by a number of sources with distinct spatial correlation structures, filtering is needed to remove in particular high frequency noise. Subsequently, bias and leakage caused by the filtering need to be corrected before the final results are interpreted as GRACE-based observations of TWS. Knowledge about the reliability and performance of different post-processing methods is highly important for the GRACE users. In this contribution, we re-assess a number of commonly used post-processing methods using a simulated GRACE-like gravity field time-series based on realistic orbits and instrument error assumptions as well as background error assumptions out of the updated ESA Earth System Model. Two non-isotropic filter methods from Kusche (2007) and Swenson and Wahr (2006) are tested. Rescaling factors estimated from five different hydrological models and the ensemble median are applied to the post-processed simulated GRACE-like TWS estimates to correct the bias and leakage. Since TWS anomalies out of the post-processed simulation results can be readily compared to the time-variable Earth System Model initially used as "truth" during the forward simulation step, we are able to thoroughly check the plausibility of our error estimation assessment and will subsequently recommend a processing strategy that shall also be applied to planned GRACE and GRACE-FO Level-3 products for hydrological applications provided by GFZ. Kusche, J. (2007): Approximate decorrelation and non-isotropic smoothing of time-variable GRACE-type gravity field models. J. Geodesy, 81 (11), 733-749, doi:10.1007/s00190-007-0143-3. Swenson, S. and Wahr, J. (2006): Post-processing removal of correlated errors in GRACE data. Geophysical Research Letters, 33(8):L08402.
Evaluation of reference current extraction methods for DSP implementation in active power filters
Energy Technology Data Exchange (ETDEWEB)
Vardar, K.; Akpinar, E.; Suergevil, T. [Dokuz Eylul University, Department of Electrical and Electronics Engineering, Kaynaklar Kampusu, 35160 Buca, Izmir (Turkey)
2009-10-15
Generation of current references constitutes an important part in the control of active power filters (APFs) used in power system, since any inaccuracy in reference currents yields to incorrect compensation. In this paper, harmonic detection methods for generating reference currents have been evaluated on the basis of three-phase balanced and unbalanced load currents processed in the digital signal processor (DSP). The advantages and disadvantages of several methods found in the literature have been discussed on the basis of simulation results. Three of these methods have been programmed in the TMS320F2812 digital signal processor (DSP) unit and their performances are evaluated from the viewpoint of practical considerations. Finally, instantaneous reactive power method to estimate the APF reference currents is implemented and its practical results obtained under balanced and unbalanced loads are given. (author)
A Finger Vein Recognition Method Using Improved Oriented Filter and Elastic Registration
Directory of Open Access Journals (Sweden)
Ma Hui
2013-07-01
Full Text Available In order to reduce the influence of relative position deviation and angle deviation between minutia point sets caused by external factors when finger vein images are obtained, a finger vein recognition method using elastic registration is presented. The proposed algorithm is based on an improved neighborhood direction template and oriented filter template which facilitates the enhancement of the finger vein image while taking full account of image orientation. Elastic registration is then applied to matching of feature points within the predefined angle and radius. Applying the idea of elastic registration to existing finger vein recognition method removes the need for perfect matching between corresponding feature points and has shown to be an effective method for dealing with the problem of nonlinear distortion of images. Experimental results show that this algorithm not only overcomes the limitations of traditional point matching method, but also effectively improves the recognition performance of the system.
A Fuzzy Preference Relation Based Method for Face Recognition by Gabor Filters
Directory of Open Access Journals (Sweden)
Soumak Biswas
2012-06-01
Full Text Available In this paper we have applied Gabor filter for fiducial point localization. After obtaining the fiducial points the number of fiducial points are reduced using a distance formula. The distance of each of this fiducial point is then calculated by the distance formula and stored in the database of the system. The same methodology is also applied on the input face which is to be matched with the faces available in the database. Then a fuzzy preference relation matrix is obtained . the largest eigen value of this matrix is then determined by algebraic method or numerical method depending on the order of the matrix. To apply the numerical method which is more easier for large order matrices we have used the C programming of this method . Once the largest eigen value is determined the corresponding priority vector can easily be obtained from which we can easily match the input face with the database.
Macroparticles Reduction Using Filter Free Cathodic Vacuum Arc Deposition Method in ZnO Thin Films.
Yuvakkumar, R; Peranantham, P; Nathanael, A Joseph; Nataraj, D; Mangalaraj, D; Hong, Sun Ig
2015-03-01
We report a new method to reduce macroparticles in ZnO thin films using filter free cathodic vacuum arc deposition without using any cooling arrangements operated at low arc current. The detailed mechanism has been proposed to reduce macroparticles during thin film deposition. The successful reduction of macroparticles was confirmed employing FESEM-EDX studies. FESEM images of ZnO thin films deposited with cathode spot to substrate distance from 10 to 20 cm revealed that the population of the macroparticles were reduced with the increase of cathode spot to substrate distances at low arc current. The prepared ZnO films were characterised and showed good structural and optical properties.
An expedited method for isolation of DNA for PCR from Magnaporthe oryzae stored on filter paper
Institute of Scientific and Technical Information of China (English)
Yulin; Jia; Yeshi; A.; Wamishe; Bo; Zhou
2014-01-01
The fungus Magnaporthe oryzae is the causal agent of a wide range of cereal diseases. For long-term preservation, the fungus is grown and stored desiccated on filter papers at –20 °C.Inoculated filter papers are cut into pieces of 0.5–1.0 cm diameter prior to storage. In the present study, a fast(11 min) and simple method of preparing DNA suitable for amplifying avirulence genes of M. oryzae by polymerase chain reaction(PCR) was developed. A piece of filter paper containing the fungus was removed from a glass bottle and placed in a 0.2 mL Eppendorf tube containing 100 μL 10 × TE. The suspension was heated for 10 min at 95 °C in a PCR machine. The tube was then centrifuged for 1 min at 3000 r min-1. One μL of 10 × TE solution containing DNA was used for PCR. A total of 28 samples were PCR tested. As a positive control, fungal DNA was extracted using a conventional DNA preparation method. DNA samples obtained from both methods were stored at 4 °C. PCR was performed with DNA on the preparation day and after 4, 8,10, and 18 days of refrigerated storage. In four samples, samples 12, 13, 14, and 28, AVR-Pi9 failed to be amplified. These four samples were tested with a different set of primers for AVR-Pi9, and for AVR-Pita1, confirming that the quality of the samples was insufficient for PCR. Overall, for nearly 90%(24/28) of the samples, the quality of the DNA prepared directly from the fungus on filter paper appeared suitable for a rapid survey of genetic identity of the rice blast fungus by PCR.This method will be useful and effective for reducing cost and time and could readily be adopted worldwide for analysis of M. oryzae and possibly other fungi.
An expedited method for isolation of DNA for PCR from Magnaporthe oryzae stored on filter paper
Directory of Open Access Journals (Sweden)
Yulin Jia
2014-10-01
Full Text Available The fungus Magnaporthe oryzae is the causal agent of a wide range of cereal diseases. For long-term preservation, the fungus is grown and stored desiccated on filter papers at –20 °C. Inoculated filter papers are cut into pieces of 0.5–1.0 cm diameter prior to storage. In the present study, a fast (11 min and simple method of preparing DNA suitable for amplifying avirulence genes of M. oryzae by polymerase chain reaction (PCR was developed. A piece of filter paper containing the fungus was removed from a glass bottle and placed in a 0.2 mL Eppendorf tube containing 100 μL 10 × TE. The suspension was heated for 10 min at 95 °C in a PCR machine. The tube was then centrifuged for 1 min at 3000 r min− 1. One μL of 10 × TE solution containing DNA was used for PCR. A total of 28 samples were PCR tested. As a positive control, fungal DNA was extracted using a conventional DNA preparation method. DNA samples obtained from both methods were stored at 4 °C. PCR was performed with DNA on the preparation day and after 4, 8, 10, and 18 days of refrigerated storage. In four samples, samples 12, 13, 14, and 28, AVR-Pi9 failed to be amplified. These four samples were tested with a different set of primers for AVR-Pi9, and for AVR-Pita1, confirming that the quality of the samples was insufficient for PCR. Overall, for nearly 90% (24/28 of the samples, the quality of the DNA prepared directly from the fungus on filter paper appeared suitable for a rapid survey of genetic identity of the rice blast fungus by PCR. This method will be useful and effective for reducing cost and time and could readily be adopted worldwide for analysis of M. oryzae and possibly other fungi.
Research on Time-series Modeling and Filtering Methods for MEMS Gyroscope Random Drift Error
Wang, Xiao Yi; Meng, Xiu Yun
2017-03-01
The precision of MEMS gyroscope is reduced by random drift error. This paper applied time series analysis to model random drift error of MEMS gyroscope. Based on the model established, Kalman filter was employed to compensate for the error. To overcome the disadvantages of conventional Kalman filter, Sage-Husa adaptive filtering algorithm was utilized to improve the accuracy of filtering results and the orthogonal property of innovation in the process of filtering was utilized to deal with outliers. The results showed that, compared with conventional Kalman filter, the modified filter can not only enhance filter accuracy, but also resist to outliers and this assured the stability of filtering thus improving the performance of gyroscopes.
Rodríguez-Caballero, E.; Afana, A.; Chamizo, S.; Solé-Benet, A.; Canton, Y.
2016-07-01
Terrestrial laser scanning (TLS), widely known as light detection and ranging (LiDAR) technology, is increasingly used to provide highly detailed digital terrain models (DTM) with millimetric precision and accuracy. In order to generate a DTM, TLS data has to be filtered from undesired spurious objects, such as vegetation, artificial structures, etc., Early filtering techniques, successfully applied to airborne laser scanning (ALS), fail when applied to TLS data, as they heavily smooth the terrain surface and do not retain their real morphology. In this article, we present a new methodology for filtering TLS data based on the geometric and radiometric properties of the scanned surfaces. This methodology was built on previous morphological filters that select the minimum point height within a sliding window as the real surface. However, contrary to those methods, which use a fixed window size, the new methodology operates under different spatial scales represented by different window sizes, and can be adapted to different types and sizes of plants. This methodology has been applied to two study areas of differing vegetation type and density. The accuracy of the final DTMs was improved by ∼30% under dense canopy plants and over ∼40% on the open spaces between plants, where other methodologies drastically underestimated the real surface heights. This resulted in more accurate representation of the soil surface and microtopography than up-to-date techniques, eventually having strong implications in hydrological and geomorphological studies.
Application of the Multimodel Ensemble Kalman Filter Method in Groundwater System
Directory of Open Access Journals (Sweden)
Liang Xue
2015-02-01
Full Text Available With the development of in-situ monitoring techniques, the ensemble Kalman filter (EnKF has become a popular data assimilation method due to its capability to jointly update model parameters and state variables in a sequential way, and to assess the uncertainty associated with estimation and prediction. To take the conceptual model uncertainty into account during the data assimilation process, a novel multimodel ensemble Kalman filter method has been proposed by incorporating the standard EnKF with Bayesian model averaging framework. In this paper, this method is applied to analyze the dataset obtained from the Hailiutu River Basin located in the northwest part of China. Multiple conceptual models are created by considering two important factors that control groundwater dynamics in semi-arid areas: the zonation pattern of the hydraulic conductivity field and the relationship between evapotranspiration and groundwater level. The results show that the posterior model weights of the postulated models can be dynamically adjusted according to the mismatch between the measurements and the ensemble predictions, and the multimodel ensemble estimation and the corresponding uncertainty can be quantified.
Analysis of Filter-Bank-Based Methods for Fast Serial Acquisition of BOC-Modulated Signals
Directory of Open Access Journals (Sweden)
Elena Simona Lohan
2007-09-01
Full Text Available Binary-offset-carrier (BOC signals, selected for Galileo and modernized GPS systems, pose significant challenges for the code acquisition, due to the ambiguities (deep fades which are present in the envelope of the correlation function (CF. This is different from the BPSK-modulated CDMA signals, where the main correlation lobe spans over 2-chip interval, without any ambiguities or deep fades. To deal with the ambiguities due to BOC modulation, one solution is to use lower steps of scanning the code phases (i.e., lower than the traditional step of 0.5 chips used for BPSK-modulated CDMA signals. Lowering the time-bin steps entails an increase in the number of timing hypotheses, and, thus, in the acquisition times. An alternative solution is to transform the ambiguous CF into an Ã¢Â€ÂœunambiguousÃ¢Â€Â CF, via adequate filtering of the signal. A generalized class of frequency-based unambiguous acquisition methods is proposed here, namely the filter-bank-based (FBB approaches. The detailed theoretical analysis of FBB methods is given for serial-search single-dwell acquisition in single path static channels and a comparison is made with other ambiguous and unambiguous BOC acquisition methods existing in the literature.
Analysis of Filter-Bank-Based Methods for Fast Serial Acquisition of BOC-Modulated Signals
Directory of Open Access Journals (Sweden)
Lohan ElenaSimona
2007-01-01
Full Text Available Binary-offset-carrier (BOC signals, selected for Galileo and modernized GPS systems, pose significant challenges for the code acquisition, due to the ambiguities (deep fades which are present in the envelope of the correlation function (CF. This is different from the BPSK-modulated CDMA signals, where the main correlation lobe spans over 2-chip interval, without any ambiguities or deep fades. To deal with the ambiguities due to BOC modulation, one solution is to use lower steps of scanning the code phases (i.e., lower than the traditional step of 0.5 chips used for BPSK-modulated CDMA signals. Lowering the time-bin steps entails an increase in the number of timing hypotheses, and, thus, in the acquisition times. An alternative solution is to transform the ambiguous CF into an "unambiguous" CF, via adequate filtering of the signal. A generalized class of frequency-based unambiguous acquisition methods is proposed here, namely the filter-bank-based (FBB approaches. The detailed theoretical analysis of FBB methods is given for serial-search single-dwell acquisition in single path static channels and a comparison is made with other ambiguous and unambiguous BOC acquisition methods existing in the literature.
Switching Kalman filter based methods for apnea bradycardia detection from ECG signals.
Montazeri Ghahjaverestan, Nasim; Shamsollahi, Mohammad B; Ge, Di; Hernández, Alfredo I
2015-09-01
Apnea bradycardia (AB) is an outcome of apnea occurrence in preterm infants and is an observable phenomenon in cardiovascular signals. Early detection of apnea in infants under monitoring is a critical challenge for the early intervention of nurses. In this paper, we introduce two switching Kalman filter (SKF) based methods for AB detection using electrocardiogram (ECG) signal.The first SKF model uses McSharry's ECG dynamical model integrated in two Kalman filter (KF) models trained for normal and AB intervals. Whereas the second SKF model is established by using only the RR sequence extracted from ECG and two AR models to be fitted in normal and AB intervals. In both SKF approaches, a discrete state variable called a switch is considered that chooses one of the models (corresponding to normal and AB) during the inference phase. According to the probability of each model indicated by this switch, the model with larger probability determines the observation label at each time instant.It is shown that the method based on ECG dynamical model can be effectively used for AB detection. The detection performance is evaluated by comparing statistical metrics and the amount of time taken to detect AB compared with the annotated onset. The results demonstrate the superiority of this method, with sensitivity and specificity 94.74[Formula: see text] and 94.17[Formula: see text], respectively. The presented approaches may therefore serve as an effective algorithm for monitoring neonates suffering from AB.
Energy Technology Data Exchange (ETDEWEB)
Hu, Aijun; Xiang, Ling [North China Electric Power University, Hebei (China)
2016-03-15
The Mathematical morphological filter (MMF) is widely applied in vibration signal processing for fault diagnosis. The Structure element (SE) and the cutoff frequency of filter have important impacts on the filtering effect, but there is no selection principle of these parameters for vibration signal processing in fault diagnosis. In this paper, the working mechanism of the MMF is studied, and a novel technique with filter characteristics and selection criterion of the MMF is proposed. The filter characteristics of morphological filter are described through frequency response analysis. The relationship between the SE length and the cutoff frequency of MMF is put forward, and the quantitative selection method of SE in engineering is proposed to effectively remove the noise and detect the impulses. The method is evaluated using both simulated signal and experimental bearing vibration signal. The results show that quantized selection method can make MMF have the better filtering effect, and can reliably extract impulsive features for bearing defect diagnosis. The study provides a theoretical basis for the application of MMF in vibration signal processing.
Modification of spent filter treat method at Uljin nuclear power plant
Energy Technology Data Exchange (ETDEWEB)
Choi, Jong rak; Ha, Jong Hyun [Nuclear Environment Technology Institute, Taejon (Korea, Republic of)
1999-07-01
Spent resin drying system(SRDS) and concentrated waste drying system (CWDS) have been introduced into Uljin NPP designed to treat spent resin, concentrated waste and spent filter at the waste cementation facility. Spent filter has been the only waste to treat at the cementation facility so that it is to become difficult to be provided the C-type containers needed to treat spent filter. To solve this problem, two programs including to change the spent filter container have been considered. One os to treat spent filter at the cementation facility using DOT - 17H drum, and another is to contain several spent filters in a High Integrated Container(HIC). (author)
Energy Technology Data Exchange (ETDEWEB)
Conde, Pablo; Gonzalez, Antonio [Institute for Instrumentation in Molecular Imaging, I3M-CSIC, Valencia (Spain); Bettiol, Marco; Fabbri, Andrea; Pani, Roberto [Department of Molecular Medicine, Sapienza University of Rome (Italy); Benlloch Baviera, José María; Talens Aguilar, Albert; Hernandez, Liczandro; Sanchez, Filomeno [Institute for Instrumentation in Molecular Imaging, I3M-CSIC, Valencia (Spain)
2015-05-18
In PET detectors based on monolithic scintillators, the photon impact position can be estimated from the light intensity distribution (LD) on the photodetector pixels. Typically, there is a poor estimation of the interaction positions towards the edges when linear algorithms such as Center of Gravity (CoG) are used. We present a novel method to determine the interaction coordinates in thick monolithic crystals filtering the digitized LDs from each gamma-event by means of an autocorrelation filter and the raise to power (RTP) positioning algorithm to reduce the border effects. The experimental setup was based on two detector blocks based on monolithic LYSO scintillator crystals (50x50x20 mm{sup 3}). Each crystal is coupled to a SiPMs array as 12x12 photosensors and an electronic readout that outputs information of each SiPM row and column. Between the detector blocks, a collimated array of 9x9 {sup 22}Na sources, separated 5 mm each other, was placed. The optimum power to use in the RTP positioning algorithm was determined using the third order intercept point (IP3) from plots of the measured coordinates versus known positions. After applying the autocorrelation and RTP fifth to the data, we found an improvement of the spatial resolution from 2.5 mm when CoG is used, to 1.2 mm in the crystal center region. In this work we show how to accurately resolve 3D photon impact coordinates in thick monolithic crystals using autocorrelation filters merged with RTP methods. After applying the new approach it is possible to accurately resolve impacts close to the entrance of 20 mm thick LYSO scintillators. The reached spatial resolution at any photon depth of interaction is comparable with state-of-the-art crystal array approaches with the advantage of the proposed work to also provide continuous depth of interaction information.
A Mixed Filter Method on Gaussian Noise%一种高斯噪声组合滤波方法
Institute of Scientific and Technical Information of China (English)
王小兵; 孙久运; 汤海燕
2011-01-01
In order to filter Gaussian noise effectively,a kind of combination filter method was put forward.Firstly,new wiener filter templates were defined by the filter method so as to filter the part of the Gaussian noise;Then the image was conducted two-dimensional wavelet decomposition,keeping the low frequency components,according to the characteristics of the noise distribution.New morphological filter templates were designed,and the wavelets coefficients were reconstructed;Finally,a new wavelet enhancement function was designed to improve the clarity of the image,and reserve the detail information of image.Experiment results show that the filtering method is better than that of the wiener filtering and morphological filtering.It is a more practical Gaussian noise denoising method.%为了有效滤除高斯噪声,提出了一种组合滤波方法.该方法首先通过定义新的维纳滤波模板进行预处理,以滤除一部分噪声;然后将图像进行二维小波分解,保留低频成分,对高频成分根据其噪声分布特征设计出新的形态学滤波模板分别进行滤波,并进行小波系数重构;最后通过设计一种新的小波增强函数,以提高图像的清晰度,最大限度保留图像细节信息.实验证明该方法滤波效果优于维纳滤波和形态学滤波,是一种较为实用的高斯噪声滤除方法.
Wu, Changdong; Liu, Zhigang; Jiang, Hua
2017-05-01
The quality of image enhancement plays an important role in the catenary fault diagnosis system based on the image processing technique. It is necessary to enhance the low contrast image of catenary for better detecting the state of catenary part. The Non-subsampled Contourlet transform (NSCT) is the improved Contourlet transform (CT), which can effectively solve the problem of artifact phenomenon in the enhanced catenary image. Besides, choosing the enhancement function and the filter of the NSCT will directly influence the image enhancement effect. In this paper, the proposed method is implemented by combining the NSCT with the nonlinear enhancement function to enhance the catenary image. First, how to choose the filter of the NSCT is discussed. Second, the NSCT is used to decompose the image. Then, the chosen nonlinear enhancement function is used to process the decomposed coefficient of the NSCT. Finally, the NSCT is inversed to obtain the enhanced image. In this paper, we evaluate our algorithm using the lifting wavelet transform, retinex enhancement method, dark channel enhancement method, curvelet transform, and CT method as a comparison to enhance a group of randomly selected low contrast catenary images, respectively. The results of comparative experiments conducted show that the proposed method can effectively enhance the catenary image, the contrast of image is improved, the catenary parts are obvious, and the artifact phenomenon is effectively eliminated, where image details (edges, textures, or smooth areas) are also well preserved. Besides, the values (detail variance-background variance, signal-to-noise ratio, and edge preservation index) of measuring the image enhancement capacity are improved, while the mean squared error value is decreased when compared to the CT method. These indicate that the proposed method is an excellent catenary image enhancement approach.
Improving accuracy in the MPM method using a null space filter
Gritton, Chris; Berzins, Martin
2017-01-01
The material point method (MPM) has been very successful in providing solutions to many challenging problems involving large deformations. Nevertheless there are some important issues that remain to be resolved with regard to its analysis. One key challenge applies to both MPM and particle-in-cell (PIC) methods and arises from the difference between the number of particles and the number of the nodal grid points to which the particles are mapped. This difference between the number of particles and the number of grid points gives rise to a non-trivial null space of the linear operator that maps particle values onto nodal grid point values. In other words, there are non-zero particle values that when mapped to the grid point nodes result in a zero value there. Moreover, when the nodal values at the grid points are mapped back to particles, part of those particle values may be in that same null space. Given positive mapping weights from particles to nodes such null space values are oscillatory in nature. While this problem has been observed almost since the beginning of PIC methods there are still elements of it that are problematical today as well as methods that transcend it. The null space may be viewed as being connected to the ringing instability identified by Brackbill for PIC methods. It will be shown that it is possible to remove these null space values from the solution using a null space filter. This filter improves the accuracy of the MPM methods using an approach that is based upon a local singular value decomposition (SVD) calculation. This local SVD approach is compared against the global SVD approach previously considered by the authors and to a recent MPM method by Zhang and colleagues.
Directory of Open Access Journals (Sweden)
K. E. Yttri
2014-07-01
Full Text Available The monosaccharide anhydrides (MAs levoglucosan, galactosan and mannosan are products of incomplete combustion and pyrolysis of cellulose and hemicelluloses, and are found to be major constituents of biomass burning aerosol particles. Hence, ambient aerosol particle concentrations of levoglucosan are commonly used to study the influence of residential wood burning, agricultural waste burning and wild fire emissions on ambient air quality. A European-wide intercomparison on the analysis of the three monosaccharide anhydrides was conducted based on ambient aerosol quartz fiber filter samples collected at a Norwegian urban background site during winter. Thus, the samples' content of MAs is representative for biomass burning particles originating from residential wood burning. The purpose of the intercomparison was to examine the comparability of the great diversity of analytical methods used for analysis of levoglucosan, mannosan and galactosan in ambient aerosol filter samples. Thirteen laboratories participated, of which three applied High-Performance Anion-Exchange Chromatography (HPAEC, four used High-Performance Liquid Chromatography (HPLC or Ultra-Performance Liquid Chromatography (UPLC, and six resorted to Gas Chromatography (GC. The analytical methods used were of such diversity that they should be considered as thirteen different analytical methods. All of the thirteen laboratories reported levels of levoglucosan, whereas nine reported data for mannosan and/or galactosan. Eight of the thirteen laboratories reported levels for all three isomers. The accuracy for levoglucosan, presented as the mean percentage error (PE for each participating laboratory, varied from −63 to 23%; however, for 62% of the laboratories the mean PE was within ±10%, and for 85% the mean PE was within ±20%. For mannosan, the corresponding range was −60 to 69%, but as for levoglucosan, the range was substantially smaller for a subselection of the laboratories; i
Shaath, Nadim A
2010-04-01
The chemistry, photostability and mechanism of action of ultraviolet filters are reviewed. The worldwide regulatory status of the 55 approved ultraviolet filters and their optical properties are documented. The photostabilty of butyl methoxydibenzoyl methane (avobenzone) is considered and methods to stabilize it in cosmetic formulations are presented.
Mie Light-Scattering Granulometer with an Adaptive Numerical Filtering Method. II. Experiments
Hespel, Laurent; Delfour, André; Guillame, Bernard
2001-02-01
A nephelometer is presented that theoretically requires no absolute calibration. This instrument is used for determining the particle-size distribution of various scattering media (aerosols, fogs, rocket exhausts, engine plumes, and the like) from angular static light-scattering measurements. An inverse procedure is used, which consists of a least-squares method and a regularization scheme based on numerical filtering. To retrieve the distribution function one matches the experimental data with theoretical patterns derived from Mie theory. The main principles of the inverse method are briefly presented, and the nephelometer is then described with the associated partial calibration procedure. Finally, the whole granulometer system (inverse method and nephelometer) is validated by comparison of measurements of scattering media with calibrated monodisperse or known size distribution functions.
Luo, Shouhua; Wu, Huazhen; Sun, Yi; Li, Jing; Li, Guang; Gu, Ning
2017-03-01
The beam hardening effect can induce strong artifacts in CT images, which result in severely deteriorated image quality with incorrect intensities (CT numbers). This paper develops an effective and efficient beam hardening correction algorithm incorporated in a filtered back-projection based maximum a posteriori (BHC-FMAP). In the proposed algorithm, the beam hardening effect is modeled and incorporated into the forward-projection of the MAP to suppress beam hardening induced artifacts, and the image update process is performed by Feldkamp–Davis–Kress method based back-projection to speed up the convergence. The proposed BHC-FMAP approach does not require information about the beam spectrum or the material properties, or any additional segmentation operation. The proposed method was qualitatively and quantitatively evaluated using both phantom and animal projection data. The experimental results demonstrate that the BHC-FMAP method can efficiently provide a good correction of beam hardening induced artefacts.
Extraction of mismatch negativity using a resampling-based spatial filtering method
Lin, Yanfei; Wu, Wei; Wu, Chaohua; Liu, Baolin; Gao, Xiaorong
2013-04-01
Objective. It is currently a challenge to extract the mismatch negativity (MMN) waveform on the basis of a small number of EEG trials, which are typically unbalanced between conditions. Approach. In order to address this issue, a method combining the techniques of resampling and spatial filtering is proposed in this paper. Specifically, the first step of the method, termed ‘resampling difference’, randomly samples the standard and deviant sweeps, and then subtracts standard sweeps from deviant sweeps. The second step of the method employs the spatial filters designed by a signal-to-noise ratio maximizer (SIM) to extract the MMN component. The SIM algorithm can maximize the signal-to-noise ratio for event-related potentials (ERPs) to improve extraction. Simulation data were used to evaluate the influence of three parameters (i.e. trial number, repeated-SIM times and sampling times) on the performance of the proposed method. Main results. Results demonstrated that it was feasible and reliable to extract the MMN waveform using the method. Finally, an oddball paradigm with auditory stimuli of different frequencies was employed to record a few trials (50 trials of deviant sweeps and 250 trials of standard sweeps) of EEG data from 11 adult subjects. Results showed that the method could effectively extract the MMN using the EEG data of each individual subject. Significance. The extracted MMN waveform has a significantly larger peak amplitude and shorter latencies in response to the more deviant stimuli than in response to the less deviant stimuli, which agreed with the MMN properties reported in previous literature using grand-averaged EEG data of multi-subjects.
Shen, Jyi-Lai; Huang, Hau-Min; Lee, Yueh-Chien; Huang, Chia-Chih; Lin, Huang-Cuang; Lin, Chin-Yuan
2009-01-01
To form a low noise figure and uniform shortpass band in optical fiber communications an improved automatic filtered power control (AFPC) pumping method is proposed here. A modulated single laser signal was entered in a closed feedback loop, in which the erbium-doped fiber amplifier (EDFA) was used as a part of the AFPC loop. Owing to the constant filtered signal and the quadrature phase shift delay inside the feedback loop, an optical pass band was uniformly formed. This EDFA attains high performance with a low noise figure simultaneously. The method was successfully applied to the fabrication of practical 12.0 m length of erbium-doped fiber pumped at 980 nm wavelength and 20 dBm power. Experiments prove that the signal gain of the loop remain flat in the range of 18.2 to 22.4 dB with a worst case error of ±0.5 dB and the noise figure was reduced by 2.2 dB at optimal, which correspond to a shortpass range of 40 nm band pass from 1525 nm to 1565 nm in wavelength. Of course, it should be possible to extent the system performance to all pumping configurations for semiconductor optical amplifiers. This provides the simplest and most economical way to transmit a well-defined band of modulated laser signal and to reject all other unwanted radiation.
Qian, Shie; Dunham, Mark E.
1996-01-01
A system and method for constructing a bank of filters which detect the presence of signals whose frequency content varies with time. The present invention includes a novel system and method for developing one or more time templates designed to match the received signals of interest and the bank of matched filters use the one or more time templates to detect the received signals. Each matched filter compares the received signal x(t) with a respective, unique time template that has been designed to approximate a form of the signals of interest. The robust time domain template is assumed to be of the order of w(t)=A(t)cos{2.pi..phi.(t)} and the present invention uses the trajectory of a joint time-frequency representation of x(t) as an approximation of the instantaneous frequency function {.phi.'(t). First, numerous data samples of the received signal x(t) are collected. A joint time frequency representation is then applied to represent the signal, preferably using the time frequency distribution series (also known as the Gabor spectrogram). The joint time-frequency transformation represents the analyzed signal energy at time t and frequency .function., P(t,f), which is a three-dimensional plot of time vs. frequency vs. signal energy. Then P(t,f) is reduced to a multivalued function f(t), a two dimensional plot of time vs. frequency, using a thresholding process. Curve fitting steps are then performed on the time/frequency plot, preferably using Levenberg-Marquardt curve fitting techniques, to derive a general instantaneous frequency function .phi.'(t) which best fits the multivalued function f(t), a trajectory of the joint time-frequency domain representation of x(t). Integrating .phi.'(t) along t yields .phi.(t), which is then inserted into the form of the time template equation. A suitable amplitude A(t) is also preferably determined. Once the time template has been determined, one or more filters are developed which each use a version or form of the time template.
Methods and apparatuses using filter banks for multi-carrier spread-spectrum signals
Moradi, Hussein; Farhang, Behrouz; Kutsche, Carl A
2014-05-20
A transmitter includes a synthesis filter bank to spread a data symbol to a plurality of frequencies by encoding the data symbol on each frequency, apply a common pulse-shaping filter, and apply gains to the frequencies such that a power level of each frequency is less than a noise level of other communication signals within the spectrum. Each frequency is modulated onto a different evenly spaced subcarrier. A demodulator in a receiver converts a radio frequency input to a spread-spectrum signal in a baseband. A matched filter filters the spread-spectrum signal with a common filter having characteristics matched to the synthesis filter bank in the transmitter by filtering each frequency to generate a sequence of narrow pulses. A carrier recovery unit generates control signals responsive to the sequence of narrow pulses suitable for generating a phase-locked loop between the demodulator, the matched filter, and the carrier recovery unit.
Methods and apparatuses using filter banks for multi-carrier spread spectrum signals
Energy Technology Data Exchange (ETDEWEB)
Moradi, Hussein; Farhang, Behrouz; Kutsche, Carl A.
2016-06-14
A transmitter includes a synthesis filter bank to spread a data symbol to a plurality of frequencies by encoding the data symbol on each frequency, apply a common pulse-shaping filter, and apply gains to the frequencies such that a power level of each frequency is less than a noise level of other communication signals within the spectrum. Each frequency is modulated onto a different evenly spaced subcarrier. A demodulator in a receiver converts a radio frequency input to a spread-spectrum signal in a baseband. A matched filter filters the spread-spectrum signal with a common filter having characteristics matched to the synthesis filter bank in the transmitter by filtering each frequency to generate a sequence of narrow pulses. A carrier recovery unit generates control signals responsive to the sequence of narrow pulses suitable for generating a phase-locked loop between the demodulator, the matched filter, and the carrier recovery unit.
Methods and apparatuses using filter banks for multi-carrier spread-spectrum signals
Moradi, Hussein; Farhang, Behrouz; Kutsche, Carl A
2014-10-14
A transmitter includes a synthesis filter bank to spread a data symbol to a plurality of frequencies by encoding the data symbol on each frequency, apply a common pulse-shaping filter, and apply gains to the frequencies such that a power level of each frequency is less than a noise level of other communication signals within the spectrum. Each frequency is modulated onto a different evenly spaced subcarrier. A demodulator in a receiver converts a radio frequency input to a spread-spectrum signal in a baseband. A matched filter filters the spread-spectrum signal with a common filter having characteristics matched to the synthesis filter bank in the transmitter by filtering each frequency to generate a sequence of narrow pulses. A carrier recovery unit generates control signals responsive to the sequence of narrow pulses suitable for generating a phase-locked loop between the demodulator, the matched filter, and the carrier recovery unit.
Methods and apparatuses using filter banks for multi-carrier spread spectrum signals
Energy Technology Data Exchange (ETDEWEB)
Moradi, Hussein; Farhang, Behrouz; Kutsche, Carl A
2017-01-31
A transmitter includes a synthesis filter bank to spread a data symbol to a plurality of frequencies by encoding the data symbol on each frequency, apply a common pulse-shaping filter, and apply gains to the frequencies such that a power level of each frequency is less than a noise level of other communication signals within the spectrum. Each frequency is modulated onto a different evenly spaced subcarrier. A demodulator in a receiver converts a radio frequency input to a spread-spectrum signal in a baseband. A matched filter filters the spread-spectrum signal with a common filter having characteristics matched to the synthesis filter bank in the transmitter by filtering each frequency to generate a sequence of narrow pulses. A carrier recovery unit generates control signals responsive to the sequence of narrow pulses suitable for generating a phase-locked loop between the demodulator, the matched filter, and the carrier recovery unit.
X-ray Ross filter method for impurity transport studies on DIII-D (abstract)
Bogatu, I. N.; Kim, J. S.; Egdell, D. H.; Snider, R. T.; Brooks, N. H.; Wade, M. R.; West, W. P.
2001-01-01
The injection of Ar into the region of the DIII-D divertor is a promising technique for energy dissipation (through radiation and collisions) and consequently for reduction of the heat load on the plates. An important problem related to this technique, is the inherent poisoning of the core plasma by migrating Ar. The Ar core contamination seems also to improve the thermal transport in an advanced operating mode of the tokamak. It is therefore of great importance to measure the evolution of the impurity concentration profile within the core plasma. This goal could be achieved by using the Ross filter method in conjunction with the existing x-ray diagnostics on DIII-D. A basic Ross filter system consists of two identical detectors placed behind two different x-ray absorbing foils looking at the same plasma volume. The foils are made of different elements or compounds with adjacent or nearly adjacent atomic numbers. Their accurate thickness causes the x-ray transmission curves of the two foils to be effectively identical over the entire energy range except within the narrow region between their absorption edges. Since the transmission characteristics of the foils above and below their absorption edges are the same, any difference in the two detected signals is proportional to the total x-ray power of the emission spectrum between these two edge energies. An x-ray Ross filter with its energy pass band centered on the Ar XVII Kα line at 3.14 keV has been designed. This allows for the discrimination of the Ar Kα line only, regardless of Ar ionization state, against any background radiation with energies outside the energy pass band. The Ross filter was installed in front of two of the fan shaped poloidal x-ray arrays on DIII-D. The first measurements showed very good discrimination against Ne, another injected impurity. Emissivity profile evolution of the Kα lines and Ar enhanced continuum within the energy pass band of the Ross filter can be determined from the x
DEFF Research Database (Denmark)
Gil-Cacho, Jose M.; van Waterschoot, Toon; Moonen, Marc
2014-01-01
In this paper, we propose a new framework to tackle the double-talk (DT) problem in acoustic echo cancellation (AEC). It is based on a frequency-domain adaptive filter (FDAF) implementation of the so-called prediction error method adaptive filtering using row operations (PEM-AFROW) leading...... to the FDAF-PEM-AFROW algorithm. We show that FDAF-PEM-AFROW is by construction related to the best linear unbiased estimate (BLUE) of the echo path. We depart from this framework to show an improvement in performance with respect to other adaptive filters minimizing the BLUE criterion, namely the PEM...
Electrically heated particulate filter regeneration methods and systems for hybrid vehicles
Energy Technology Data Exchange (ETDEWEB)
Gonze, Eugene V. (Pinckney, MI); Paratore, Jr., Michael J. (Howell, MI)
2010-10-12
A control system for controlling regeneration of a particulate filter for a hybrid vehicle is provided. The system generally includes a regeneration module that controls current to the particulate filter to initiate regeneration. An engine control module controls operation of an engine of the hybrid vehicle based on the control of the current to the particulate filter.
Non-monotonicity of trace distance under tensor products
Energy Technology Data Exchange (ETDEWEB)
Maziero, Jonas, E-mail: jonas.maziero@ufsm.br [Universidade Federal de Santa Maria (UFSM), RS (Brazil). Departamento de Fisica
2015-10-15
The trace distance (TD) possesses several of the good properties required for a faithful distance measure in the quantum state space. Despite its importance and ubiquitous use in quantum information science, one of its questionable features, its possible non-monotonicity under taking tensor products of its arguments (NMuTP), has been hitherto unexplored. In this article, we advance analytical and numerical investigations of this issue considering different classes of states living in a discrete and finite dimensional Hilbert space. Our results reveal that although this property of TD does not show up for pure states and for some particular classes of mixed states, it is present in a non-negligible fraction of the regarded density operators. Hence, even though the percentage of quartets of states leading to the NMuTP drawback of TD and its strength decrease as the system's dimension grows, this property of TD must be taken into account before using it as a figure of merit for distinguishing mixed quantum states. (author)
American Society for Testing and Materials. Philadelphia
2008-01-01
1.1 These test methods cover the determination of the size distribution and quantity of particulate matter contamination from aerospace fluids isolated on a membrane filter. The microscopical techniques described may also be applied to other properly prepared samples of small particles. Two test methods are described for sizing particles as follows: 1.1.1 Test Method A—Particle sizes are measured as the diameter of a circle whose area is equal to the projected area of the particle. 1.1.2 Test Method B—Particle sizes are measured by their longest dimension. 1.2 The test methods are intended for application to particle contamination determination of aerospace fluids, gases, surfaces, and environments. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 These test methods do not provide for sizing particles smaller than 5 μm. Note 1—Results of these methods are subject to variables inherent in any statistical method. The...
Improved sample filtering method for measuring end-to-end path capacity
Institute of Scientific and Technical Information of China (English)
LI Wen-wei; TANG Jun-long; ZHANG Da-fang; XIE Gao-gang
2007-01-01
By analyzing the effect of cross traffic (CT) enforced on packet delay, an improved path capacity measurement method,pcapminp algorithm, was proposed. With this method, path capacity was measured by filtering probe samples based on measured minimum packet-pair delay. The measurability of minimum packet-pair delay was also analyzed by simulation. The results show that,when comparing with pathrate, ifthe CT load is light, both pcapminp and pathrate have similar accuracy; but in the case of heavy CT load, pcapminp is more accurate than Pathrate. When CT load reaches 90%, pcapminp algorithm has only 5% measurement error,which is 10% lower than that of pathrate algorithm. At any CT load levels, the probe cost of pcapminp algorithm is two magnitudes smaller than that of pathrate, and the measurement duration is one magnitude shorter than that of pathrate algorithm.
Mathematical Description of Acousto-Optic Tunable Filter Orthogonal Polarizing Method
Institute of Scientific and Technical Information of China (English)
XU Kexin; WEN Huizhi; ZHANG Hao; FAN Guofang; YANG Jisheng
2005-01-01
The transfer function of the optical splitting system of the acousto-optic tunable filter (AOTF) is deduced to be a reference to optical design. The characteristic matrix (transfer function) of AOTF is used to describe quantitatively the characters of polarization elements in the orthogonal polarizing system. According to the characteristic matrix, the included angle of polarizer's transmission direction and polarization analyzer's transmission direction should be 90°. As a result the signal to noise ratio increased about 20 times though the light intensity was reduced to 54.3% polarization analyzer are 0.74, which is an intrinsic character. The orthogonal polarizing method is an effective method to get rid of the influence of zero order light and improve the spectrum resolution and signal-to-noise ratio.
Characterization of filter cartridges from the IEA-R1 reactor by radiochemical method
Energy Technology Data Exchange (ETDEWEB)
Geraldo, Bianca; Vicente, Roberto; Ferreira, Robson J.; Goes, Marcos M.; Marumo, Julio T., E-mail: bgeraldo@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)
2015-07-01
The filter cartridges used in water purification system of research nuclear reactor IEA-R1 are considered radioactive wastes after their useful life. The characterization of these wastes is one of the stages of management, which aims to identify and quantify the radionuclides present, including those known as 'difficult to measure' (DTM) radionuclides. Establish a radiochemical analysis methodology for this type of waste is a difficult job, not only by the application of these techniques, but also by the amount of radionuclides that should be analyzed. In the waste produced in a nuclear reactor, the most important radionuclides are fission products, activation products and transuranic elements. Since these radionuclides emit gamma radiation not measurable in its decay process and consequently are difficult to measure, their concentrations can be estimated by indirect methods such as scale factors. This method is used to evaluate the DTM concentration, which is represented by alpha and beta nuclides using the correlation between them and the radionuclide key, a gamma emitter. The objective of this work is to describe a radiochemical analysis methodology for gamma emitter nuclides, present in the filter cartridges, evaluating the activity and concentrations by destructive assays. At the same time, two studies have been performed by non-destructive assays, the first one based on dose rates and the point kernel method to correlate the results and the second one based on calibration efficiency with Monte Carlo method. These studies belong to the radioactive waste characterization program that has been conducted at the Waste Management Laboratory of Nuclear and Energy Research Institute, IPEN-CNEN/SP. (author)
A Position Estimation Method of the Control Rod Guide Tube with Matched Filters
Energy Technology Data Exchange (ETDEWEB)
Lee, Jae C.; Seop, Jun H.; Choi, Yu R.; Kim, Jae H. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2005-07-01
The risk that PWR guide tube support pins will crack has increased the necessity for the development of inspection methods and equipment. A special remote controlled manipulator has been widely used to inspect the guide tube support pins. In real situations, the manipulator is lowered into the internals pool and all the movements are monitored and controlled from a desk at the side of the pool. Because the diameter of the split pins is as small as 25mm, locating the ultrasonic transducer to the pins by a manual operation is a somewhat tedious task. To overcome this problem, a rail was placed on the bottom of the pool before the internals of the reactor vessel were lifted and lowered on to their stand. In this paper, we presented one method to eliminate this troublesome job by using a vision sensor already being used to monitor the manipulator's movements. There were some successful researches in designing controls for many dynamic systems in the case of their current position and where the desired trajectories are well defined. But a current position estimation of a robot and/or environmental objects is another problem that must be solved. A Matched filter algorithm is employed as a method for an automatic detection of the guide tube's and support pin's relative position to that of the robot. First, we construct two raw images corresponding to the guide tube and the support pin respectively. These are simply binary-valued image files that contain the shapes of each object. Next, we performed a 2-D FFT(fast fourier transform) on them. The transformed data files are the matched-filters to detect the presence of a guide tube and/or support pins and to estimate the positions of them. The cross correlation between the matched-filter and real input image can be calculated by the method of multiplying them followed by an inverse FFT. If the resulting value is greater than the pre-determined threshold value, we can conclude that there is at least one object
Payne, G S; Harris, L M; Cairns, G.S.; Messiou, C; deSouza, N M; Macdonald, A.; Saran, F.; Leach, M. O.
2016-01-01
1H MRS measurements of lactate are often confounded by overlapping lipid signals. Double‐quantum (DQ) filtering eliminates lipid signals and permits single‐shot measurements, which avoid subtraction artefacts in moving tissues. This study evaluated a single‐voxel‐localized DQ filtering method qualitatively and quantitatively for measuring lactate concentrations in the presence of lipid, using high‐grade brain tumours in which the results could be compared with standard acquisition as a refere...
Energy Technology Data Exchange (ETDEWEB)
Geryes, T., E-mail: tony.geryes@irsn.f [Institut de Radioprotection et de Surete Nucleaire (IRSN), Service d' Etudes et de Recherches en, Aerodispersion des polluants et en Confinement, B.P 68, Bat. 389, 91192 Gif-sur-Yvette Cedex (France); Centre d' Etudes et de Recherches en Thermique, Environnement et Systeme (CERTES), Universite Paris 12, 61 av. du General de Gaulle, 94010 Creteil Cedex (France); Monsanglant-Louvet, C. [Institut de Radioprotection et de Surete Nucleaire (IRSN), Service d' Etudes et de Recherches en, Aerodispersion des polluants et en Confinement, B.P 68, Bat. 389, 91192 Gif-sur-Yvette Cedex (France); Gehin, E. [Centre d' Etudes et de Recherches en Thermique, Environnement et Systeme (CERTES), Universite Paris 12, 61 av. du General de Gaulle, 94010 Creteil Cedex (France)
2009-10-15
Air sampling for particulate radioactive material involves collecting airborne particles on a filter in order to measure the radioactivity in the environment or in working areas. The amount of alpha radioactivity collected on the sampling filter is frequently determined by global alpha-particles measurements. Several factors can affect the alpha energy while passing through the filter to reach the detector. The most affecting factor on the alpha spectrum degradation is the absorption of alpha particle energies in the filter fibers. The fibers' density can range from 1 to 9 mg cm{sup -2}. The counting losses can accordingly be important, and the global activity in the filter can be underestimated. The complexity of the experiments and the diversity of the filter types, filtration conditions as well as detector types used for survey incite us to formulate a numerical model to simulate the correction factors of the degraded activity. Comparisons between experimental and simulated correction factors for a commonly used filter are presented. The good agreement found between experimental and calculated values validates the method in the studied conditions.
A transition model for quality-of-life data with non-ignorable non-monotone missing data.
Liao, Kaijun; Freres, Derek R; Troxel, Andrea B
2012-12-10
In this paper, we consider a full likelihood method to analyze continuous longitudinal responses with non-ignorable non-monotone missing data. We consider a transition probability model for the missingness mechanism. A first-order Markov dependence structure is assumed for both the missingness mechanism and observed data. This process fits the natural data structure in the longitudinal framework. Our main interest is in estimating the parameters of the marginal model and evaluating the missing-at-random assumption in the Effects of Public Information Study, a cancer-related study recently conducted at the University of Pennsylvania. We also present a simulation study to assess the performance of the model.
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
This paper presents an infeasible-interior-point algorithm for aclass of nonmonotone complementarity problems, and analyses its convergence and computational complexity. The results indicate that the proposed algorithm is a polynomial-time one.
Periodic Solutions of Periodic Delay Predator-Prey System with Nonmonotonic Functional Response
Institute of Scientific and Technical Information of China (English)
宋永利; 韩茂安
2003-01-01
By using the continuation theorem of coincidence degree theory, sufficient conditions are obtained for theexistence of positive periodic solutions of a delayed predator-prey system with nonmonotonic functional response ina periodic environment.
Energy Technology Data Exchange (ETDEWEB)
Jang, Seunghyun; Jae, Moosung [Hanyang University, Seoul (Korea, Republic of)
2016-10-15
The human failure events (HFEs) are considered in the development of system fault trees as well as accident sequence event trees in part of Probabilistic Safety Assessment (PSA). As a method for analyzing the human error, several methods, such as Technique for Human Error Rate Prediction (THERP), Human Cognitive Reliability (HCR), and Standardized Plant Analysis Risk-Human Reliability Analysis (SPAR-H) are used and new methods for human reliability analysis (HRA) are under developing at this time. This paper presents a dynamic HRA method for assessing the human failure events and estimation of human error probability for filtered containment venting system (FCVS) is performed. The action associated with implementation of the containment venting during a station blackout sequence is used as an example. In this report, dynamic HRA method was used to analyze FCVS-related operator action. The distributions of the required time and the available time were developed by MAAP code and LHS sampling. Though the numerical calculations given here are only for illustrative purpose, the dynamic HRA method can be useful tools to estimate the human error estimation and it can be applied to any kind of the operator actions, including the severe accident management strategy.
Davy, Pamela M.; Tremper, Anja H.; Nicolosi, Eleonora M. G.; Quincey, Paul; Fuller, Gary W.
2017-03-01
Atmospheric particulate black carbon has been linked to adverse health outcomes. Additional black carbon measurements would aid a better understanding of population exposure in epidemiological studies as well as the success, or otherwise, of relevant abatement technologies and policies. Two light absorption measurement methods of particles collected on filters have been applied to four different types of filters to provide estimations of particulate black carbon concentrations. The ratio of transmittance (lnI0/I) to reflectance (lnR0/R) varied by filter type and ranged from close to 0.5 (as expected from simple theory) to 1.35 between the four filter types tested. The relationship between light absorption and black carbon, measured by the thermal EC(TOT) method, was nonlinear and differed between filter type and measurement method. This is particularly relevant to epidemiological studies that use light absorption as an exposure metric. An extensive archive of filters was used to derive loading factors and mass extinction coefficients for each filter type. Particulate black carbon time series were then calculated at locations where such measurements were not previously available. When applied to two roads in London, black carbon concentrations were found to have increased between 2011 and 2013, by 0.3 (CI: -0.1, 0.5) and 0.4 (CI: 0.1, 0.9) μg m-3 year-1, in contrast to the expectation from exhaust abatement policies. New opportunities using archived or bespoke filter collections for studies on the health effects of black carbon and the efficacy of abatement strategies are created.
Lousada-Ferreira, Maria; Krzeminski, Pawel; Geilvoet, Stefan; Moreau, Adrien; Gil, Jose A; Evenblij, Herman; van Lier, Jules B; van der Graaf, Jaap H J M
2014-04-30
Prevention and removal of fouling is often the most energy intensive process in Membrane Bioreactors (MBRs), responsible for 40% to 50% of the total specific energy consumed in submerged MBRs. In the past decade, methods were developed to quantify and qualify fouling, aiming to support optimization in MBR operation. Therefore, there is a need for an evaluation of the lessons learned and how to proceed. In this article, five different methods for measuring MBR activated sludge filterability and critical flux are described, commented and evaluated. Both parameters characterize the fouling potential in full-scale MBRs. The article focuses on the Delft Filtration Characterization method (DFCm) as a convenient tool to characterize sludge properties, namely on data processing, accuracy, reproducibility, reliability, and applicability, defining the boundaries of the DFCm. Significant progress was made concerning fouling measurements in particular by using straight forward approaches focusing on the applicability of the obtained results. Nevertheless, a fouling measurement method is still to be defined which is capable of being unequivocal, concerning the fouling parameters definitions; practical and simple, in terms of set-up and operation; broad and useful, in terms of obtained results. A step forward would be the standardization of the aforementioned method to assess the sludge filtration quality.
A Method of Effective Quarry Water Purifying Using Artificial Filtering Arrays
Tyulenev, M.; Garina, E.; Khoreshok, A.; Litvin, O.; Litvin, Y.; Maliukhina, E.
2017-01-01
The development of open pit mining in the large coal basins of Russia and other countries increases their negative impact on the environment. Along with the damage of land and air pollution by dust and combustion gases of blasting, coal pits have a significant negative impact on water resources. Polluted quarry water worsens the ecological situation on a much larger area than covered by air pollution and land damage. This significantly worsens the conditions of people living in cities and towns located near the coal pits, and complicates the subsequent restoration of the environment, irreversibly destroying the nature. Therefore, the research of quarry wastewater purifying is becoming an important mater for scholars of technical colleges and universities in the regions with developing open-pit mining. This paper describes the method of determining the basic parameters of the artificial filtering arrays formed on coal pits of Kuzbass (Western Siberia, Russia), and gives recommendations on its application.
A rapid and economic in-house DNA purification method using glass syringe filters.
Directory of Open Access Journals (Sweden)
Yun-Cheol Kim
Full Text Available BACKGROUND: Purity, yield, speed and cost are important considerations in plasmid purification, but it is difficult to achieve all of these at the same time. Currently, there are many protocols and kits for DNA purification, however none maximize all four considerations. METHODOLOGY/PRINCIPAL FINDINGS: We now describe a fast, efficient and economic in-house protocol for plasmid preparation using glass syringe filters. Plasmid yield and quality as determined by enzyme digestion and transfection efficiency were equivalent to the expensive commercial kits. Importantly, the time required for purification was much less than that required using a commercial kit. CONCLUSIONS/SIGNIFICANCE: This method provides DNA yield and quality similar to that obtained with commercial kits, but is more rapid and less costly.
Li, Xian-ing; Lu, Xi-wu; Song, Hai-liang; Osamu, Nishimura; Yuhei, Inamori
2005-03-01
The potential of nitrification and denitrification of sediment and the density of ammonium-oxidizing bacteria and nitrite-oxidizing bacteria in sediment in water quality purifying system with hydroponic bio-filter method (HBFM) were measured. The variation of nitrification and denitrification potential of the sediment along the stream way was quantitatively studied. The results show that among the sediments from front, middle and retral part of the stream way, the sediment from middle part reached a maximum nitrification potential . nitrification potential of 4.76 x 10(-6) g/(g x h), while the sediment from front part reached a maximum denitrification potential of 8 .1 x 10(-7) g/(g x h). The distribution of nitrification potential accords with the ammonium-oxidizing bacteria density. The key for improving nitrogen removal efficiency of HBFM system consists in changing nitrification & denitrification region distributing and accordingly enhances denitrification process.
Dolfus, Claire; Piton, Nicolas; Toure, Emmanuel; Sabourin, Jean-Christophe
2015-10-01
Circulating tumor cells (CTCs) arise from primary or secondary tumors and enter the bloodstream by active or passive intravasation. Given the low number of CTCs, enrichment is necessary for detection. Filtration methods are based on selection of CTCs by size using a filter with 6.5 to 8 µm pores. After coloration, collected CTCs are evaluated according to morphological criteria. Immunophenotyping and fluorescence in situ hybridization techniques may be used. Selected CTCs can also be cultivated in vitro to provide more material. Analysis of genomic mutations is difficult because it requires adapted techniques due to limited DNA materials. Filtration-selected CTCs have shown prognostic value in many studies but multicentric validating trials are mandatory to strengthen this assessment. Other clinical applications are promising such as follow-up, therapy response prediction and diagnosis. Microfluidic emerging systems could optimize filtration-selected CTCs by increasing selection accuracy.
Advances in analytical methods and occurrence of organic UV-filters in the environment — A review
Energy Technology Data Exchange (ETDEWEB)
Ramos, Sara; Homem, Vera, E-mail: vhomem@fe.up.pt; Alves, Arminda; Santos, Lúcia
2015-09-01
UV-filters are a group of compounds designed mainly to protect skin against UVA and UVB radiation, but they are also included in plastics, furniture, etc., to protect products from light damage. Their massive use in sunscreens for skin protection has been increasing due to the awareness of the chronic and acute effects of UV radiation. Some organic UV-filters have raised significant concerns in the past few years for their continuous usage, persistent input and potential threat to ecological environment and human health. UV-filters end up in wastewater and because wastewater treatment plants are not efficient in removing them, lipophilic compounds tend to sorb onto sludge and hydrophilics end up in river water, contaminating the existing biota. To better understand the risk associated with UV-filters in the environment a thorough review regarding their physicochemical properties, toxicity and environmental degradation, analytical methods and their occurrence was conducted. Higher UV-filter concentrations were found in rivers, reaching 0.3 mg/L for the most studied family, the benzophenone derivatives. Concentrations in the ng to μg/L range were also detected for the p-aminobenzoic acid, cinnamate, crylene and benzoyl methane derivatives in lake and sea water. Although at lower levels (few ng/L), UV-filters were also found in tap and groundwater. Swimming pool water is also a sink for UV-filters and its chlorine by-products, at the μg/L range, highlighting the benzophenone and benzimidazole derivatives. Soils and sediments are not frequently studied, but concentrations in the μg/L range have already been found especially for the benzophenone and crylene derivatives. Aquatic biota is frequently studied and UV-filters are found in the ng/g-dw range with higher values for fish and mussels. It has been concluded that more information regarding UV-filter degradation studies both in water and sediments is necessary and environmental occurrences should be monitored more
Directory of Open Access Journals (Sweden)
Ping Zhang
2016-01-01
Full Text Available Variational multiscale element free Galerkin (VMEFG method is applied to Burgers’ equation. It can be found that, for the very small diffusivity coefficients, VMEFG method still suffers from instability in the presence of boundary or interior layers. In order to overcome this problem, the high order low-pass filter is used to smooth the solution. Three test examples with very small diffusion are presented and the solutions obtained are compared with exact solutions and some other numerical methods. The numerical results are found in which the VMEFG coupled with low-pass filter works very well for Burgers’ equation with very small diffusivity coefficients.
Influence of Post-treatment Methods on Pressure Change of Filter Bag
Directory of Open Access Journals (Sweden)
Yihua Yin
2016-01-01
Full Text Available The PPS needle-punched non-woven filters with different post-treatments were studied by filter testing system. The pressure drop was measured at various filtration velocity, dust deposition time and the temperature during the experiment; and the effect of dust-cleaning as the consequence of pressure of filter bag was measured. The results showed that post-treatments transformed the surfaces of filters, and the dust formation differed greatly. Excessively high filtration velocity decreased the peak pressure in the process of dust-cleaning. The pressure of filter bag was increased as the dust layers were thickened. The higher temperature in filtration rose the peak pressure of filter bag, but decreased the rate of rising.
Lee, Sungho; Kim, Tae-Hoon; Kang, Jonghyuk; Yang, Cheol-Woong
2016-12-01
As the feature size of devices continues to decrease, transmission electron microscopy (TEM) is becoming indispensable for measuring the critical dimension (CD) of structures. Semiconductors consist primarily of silicon-based materials such as silicon, silicon dioxide, and silicon nitride, and the electrons transmitted through a plan-view TEM sample provide diverse information about various overlapped silicon-based materials. This information is exceedingly complex, which makes it difficult to clarify the boundary to be measured. Therefore, we propose a simple measurement method using energy-filtered TEM (EF-TEM). A precise and effective measurement condition was obtained by determining the maximum value of the integrated area ratio of the electron energy loss spectrum at the boundary to be measured. This method employs an adjustable slit allowing only electrons with a certain energy range to pass. EF-TEM imaging showed a sharp transition at the boundary when the energy-filter’s passband centre was set at 90 eV, with a slit width of 40 eV. This was the optimum condition for the CD measurement of silicon-based materials involving silicon nitride. Electron energy loss spectroscopy (EELS) and EF-TEM images were used to verify this method, which makes it possible to measure the transistor gate length in a dynamic random access memory manufactured using 35 nm process technology. This method can be adapted to measure the CD of other non-silicon-based materials using the EELS area ratio of the boundary materials.
A robust infrared dim target detection method based on template filtering and saliency extraction
Wang, Wenguang; Li, Chenming; Shi, Jianing
2015-11-01
Dim target detection in infrared image with complex background and low signal-clutter ratio (SCR) is a significant and difficult task in the infrared target tracking system. A robust infrared dim target detection method based on template filtering and saliency extraction is proposed in this paper. The weighted gray map is obtained from the infrared image to highlight the target which is brighter than its neighbors and has weak correlation with its background. The target saliency map is then calculated by phase spectrum of Fourier Transform, so that the dim target detection could be converted to salient region extraction. The potential targets are finally extracted by combining the two maps. Moreover, position discrimination between targets in the two maps is used to exclude the false alarms and extract the targets. Experimental results on measured images indicate that our method is feasible, adaptable and robust in different backgrounds. The ROC (Receiver Operating Characteristic) curves obtained from the simulated images demonstrate the proposed method outperforms some existing typical methods in both detection rate and false alarm rate, for target detection with low SCR.
Directory of Open Access Journals (Sweden)
Xixiang Liu
2014-01-01
Full Text Available In the initial alignment process of strapdown inertial navigation system (SINS, large initial misalignment angles always bring nonlinear problem, which causes alignment failure when the classical linear error model and standard Kalman filter are used. In this paper, the problem of large misalignment angles in SINS initial alignment is investigated, and the key reason for alignment failure is given as the state covariance from Kalman filter cannot represent the true one during the steady filtering process. According to the analysis, an alignment method for SINS based on multiresetting the state covariance matrix of Kalman filter is designed to deal with large initial misalignment angles, in which classical linear error model and standard Kalman filter are used, but the state covariance matrix should be multireset before the steady process until large misalignment angles are decreased to small ones. The performance of the proposed method is evaluated by simulation and car test, and the results indicate that the proposed method can fulfill initial alignment with large misalignment angles effectively and the alignment accuracy of the proposed method is as precise as that of alignment with small misalignment angles.
A method of using noise as a test pattern for determining image enhancement filters
Energy Technology Data Exchange (ETDEWEB)
Burgess, A.E. (Rochester Inst. of Tech., NY (United States)); Ghandeharian, H. (Stentor Canadian Network Management, Ottawa, ON (Canada))
1994-08-01
Many digitally based medical imaging systems include both reconstruction algorithms and additional image filters designed to enhance certain image features. The purpose of this note is to describe a simple procedure for determining the spatial frequency response of these proprietary enhancement filters. The technique uses image noise as a test pattern. The procedure consists of acquiring a small number of noise-only data sets of a uniform phantom and reconstructing the images using the different filters with repeated us of the noise data sets. A straightforward analysis then yields the enhancement filter frequency responses. (author).
Meng, S.; Xie, X.
2014-12-01
Hydrological model performance is usually not as acceptable as expected due to limited measurements and imperfect parameterization which is attributable to the uncertainties from model parameters and model structures. In applications, a general assumption is hold that model parameters are constant in a stationary condition during the simulation period, and the parameters are generally prescribed though calibration with observed data. In reality, but the model parameters related to the physical or conceptual characteristics of a catchment will travel in nonstationary conditions in response to climate transition and land use alteration. The travels or changes of parameters are especially evident for long-term hydrological simulations. Therefore, the assumption of using constant parameters under nonstationary condition is inappropriate, and it will deliver errors from the parameters to the outputs during the simulation and prediction. Even though a few of studies have acknowledged the parameter travel or change, little attention has been paid on the estimation of changing parameters. In this study, we employ an ensemble Kalman filter (EnKF) based method to trace parameter changes in real time. Through synthetic experiments, the capability of the EnKF-based is demonstrated by assimilating runoff observations into a rainfall-runoff model, i.e., the Xinanjing Model. In addition to the stationary condition, three typical nonstationary conditions are considered, i.e., the leap, linear and Ω-shaped transitions. To examine the robustness of the method, different errors from rainfall input, modelling and observations are investigated. The shuffled complex evolution (SCE-UA) algorithm is applied under the same conditions to make a comparison. The results show that the EnKF-based method is capable of capturing the general pattern of the parameter travels even for high levels of uncertainties. It provides better estimates than the SCE-UA method does by taking advantages of real
DEFF Research Database (Denmark)
Li, Zipeng; Jiang, Aiting; Shen, Pan;
2016-01-01
, this paper presents a systematic design method for the LCL-LC filtered grid-connected photovoltaic (PV) system. With this method, controller parameters and the active damping feedback coefficient are easily obtained by specifying the system stability and dynamic performance indices, and it is more convenient...
Gao, Hao
2015-01-01
This work is to develop a general framework, namely filtered iterative reconstruction (FIR) method, to incorporate analytical reconstruction (AR) method into iterative reconstruction (IR) method, for enhanced CT image quality. Specifically, FIR is formulated as a combination of filtered data fidelity and sparsity regularization, and then solved by proximal forward-backward splitting (PFBS) algorithm. As a result, the image reconstruction decouples data fidelity and image regularization with a two-step iterative scheme, during which an AR-projection step updates the filtered data fidelity term, while a denoising solver updates the sparsity regularization term. During the AR-projection step, the image is projected to the data domain to form the data residual, and then reconstructed by certain AR to a residual image which is in turn weighted together with previous image iterate to form next image iterate. Since the eigenvalues of AR-projection operator are close to the unity, PFBS based FIR has a fast convergenc...
DEFF Research Database (Denmark)
Drews, Martin; Lauritzen, Bent; Madsen, Henrik
2005-01-01
A Kalman filter method is discussed for on-line estimation of radioactive release and atmospheric dispersion from a time series of off-site radiation monitoring data. The method is based on a state space approach, where a stochastic system equation describes the dynamics of the plume model...... parameters, and the observables are linked to the state variables through a static measurement equation. The method is analysed for three simple state space models using experimental data obtained at a nuclear research reactor. Compared to direct measurements of the atmospheric dispersion, the Kalman filter...... estimates are found to agree well with the measured parameters, provided that the radiation measurements are spread out in the cross-wind direction. For less optimal detector placement it proves difficult to distinguish variations in the source term and plume height; yet the Kalman filter yields consistent...
Adaptive filtering methods for identifying cross-frequency couplings in human EEG.
Directory of Open Access Journals (Sweden)
Jérôme Van Zaen
Full Text Available Oscillations have been increasingly recognized as a core property of neural responses that contribute to spontaneous, induced, and evoked activities within and between individual neurons and neural ensembles. They are considered as a prominent mechanism for information processing within and communication between brain areas. More recently, it has been proposed that interactions between periodic components at different frequencies, known as cross-frequency couplings, may support the integration of neuronal oscillations at different temporal and spatial scales. The present study details methods based on an adaptive frequency tracking approach that improve the quantification and statistical analysis of oscillatory components and cross-frequency couplings. This approach allows for time-varying instantaneous frequency, which is particularly important when measuring phase interactions between components. We compared this adaptive approach to traditional band-pass filters in their measurement of phase-amplitude and phase-phase cross-frequency couplings. Evaluations were performed with synthetic signals and EEG data recorded from healthy humans performing an illusory contour discrimination task. First, the synthetic signals in conjunction with Monte Carlo simulations highlighted two desirable features of the proposed algorithm vs. classical filter-bank approaches: resilience to broad-band noise and oscillatory interference. Second, the analyses with real EEG signals revealed statistically more robust effects (i.e. improved sensitivity when using an adaptive frequency tracking framework, particularly when identifying phase-amplitude couplings. This was further confirmed after generating surrogate signals from the real EEG data. Adaptive frequency tracking appears to improve the measurements of cross-frequency couplings through precise extraction of neuronal oscillations.
Adaptive filtering methods for identifying cross-frequency couplings in human EEG.
Van Zaen, Jérôme; Murray, Micah M; Meuli, Reto A; Vesin, Jean-Marc
2013-01-01
Oscillations have been increasingly recognized as a core property of neural responses that contribute to spontaneous, induced, and evoked activities within and between individual neurons and neural ensembles. They are considered as a prominent mechanism for information processing within and communication between brain areas. More recently, it has been proposed that interactions between periodic components at different frequencies, known as cross-frequency couplings, may support the integration of neuronal oscillations at different temporal and spatial scales. The present study details methods based on an adaptive frequency tracking approach that improve the quantification and statistical analysis of oscillatory components and cross-frequency couplings. This approach allows for time-varying instantaneous frequency, which is particularly important when measuring phase interactions between components. We compared this adaptive approach to traditional band-pass filters in their measurement of phase-amplitude and phase-phase cross-frequency couplings. Evaluations were performed with synthetic signals and EEG data recorded from healthy humans performing an illusory contour discrimination task. First, the synthetic signals in conjunction with Monte Carlo simulations highlighted two desirable features of the proposed algorithm vs. classical filter-bank approaches: resilience to broad-band noise and oscillatory interference. Second, the analyses with real EEG signals revealed statistically more robust effects (i.e. improved sensitivity) when using an adaptive frequency tracking framework, particularly when identifying phase-amplitude couplings. This was further confirmed after generating surrogate signals from the real EEG data. Adaptive frequency tracking appears to improve the measurements of cross-frequency couplings through precise extraction of neuronal oscillations.
Li, Ke; Zhang, Qiuju; Wang, Kun; Chen, Peng; Wang, Huaqing
2016-01-08
A new fault diagnosis method for rotating machinery based on adaptive statistic test filter (ASTF) and Diagnostic Bayesian Network (DBN) is presented in this paper. ASTF is proposed to obtain weak fault features under background noise, ASTF is based on statistic hypothesis testing in the frequency domain to evaluate similarity between reference signal (noise signal) and original signal, and remove the component of high similarity. The optimal level of significance α is obtained using particle swarm optimization (PSO). To evaluate the performance of the ASTF, evaluation factor Ipq is also defined. In addition, a simulation experiment is designed to verify the effectiveness and robustness of ASTF. A sensitive evaluation method using principal component analysis (PCA) is proposed to evaluate the sensitiveness of symptom parameters (SPs) for condition diagnosis. By this way, the good SPs that have high sensitiveness for condition diagnosis can be selected. A three-layer DBN is developed to identify condition of rotation machinery based on the Bayesian Belief Network (BBN) theory. Condition diagnosis experiment for rolling element bearings demonstrates the effectiveness of the proposed method.
Calin, Mihaela Antonina; Coman, Toma; Parasca, Sorin Viorel; Bercaru, Nicolae; Savastru, Roxana; Manea, Dragos
2015-04-01
Hyperspectral imaging is a technology that is beginning to occupy an important place in medical research with good prospects in future clinical applications. We evaluated the role of hyperspectral imaging in association with a mixture-tuned matched filtering method in the characterization of open wounds. The methodology and the processing steps of the hyperspectral image that have been performed in order to obtain the most useful information about the wound are described in detail. Correlations between the hyperspectral image and clinical examination are described, leading to a pattern that permits relative evaluation of the square area of the wound and its different components in comparison with the surrounding normal skin. Our results showed that the described method can identify different types of tissues that are present in the wounded area and can objectively measure their respective abundance, which proves its value in wound characterization. In conclusion, the method that was described in this preliminary case presentation shows promising results, but needs further evaluation in order to become a reliable and useful tool.
Ping, Jing
2017-05-19
Optimal management of subsurface processes requires the characterization of the uncertainty in reservoir description and reservoir performance prediction. For fractured reservoirs, the location and orientation of fractures are crucial for predicting production characteristics. With the help of accurate and comprehensive knowledge of fracture distributions, early water/CO 2 breakthrough can be prevented and sweep efficiency can be improved. However, since the rock property fields are highly non-Gaussian in this case, it is a challenge to estimate fracture distributions by conventional history matching approaches. In this work, a method that combines vector-based level-set parameterization technique and ensemble Kalman filter (EnKF) for estimating fracture distributions is presented. Performing the necessary forward modeling is particularly challenging. In addition to the large number of forward models needed, each model is used for sampling of randomly located fractures. Conventional mesh generation for such systems would be time consuming if possible at all. For these reasons, we rely on a novel polyhedral mesh method using the mimetic finite difference (MFD) method. A discrete fracture model is adopted that maintains the full geometry of the fracture network. By using a cut-cell paradigm, a computational mesh for the matrix can be generated quickly and reliably. In this research, we apply this workflow on 2D two-phase fractured reservoirs. The combination of MFD approach, level-set parameterization, and EnKF provides an effective solution to address the challenges in the history matching problem of highly non-Gaussian fractured reservoirs.
Planetary gearbox fault feature enhancement based on combined adaptive filter method
Directory of Open Access Journals (Sweden)
Shuangshu Tian
2015-12-01
Full Text Available The reliability of vibration signals acquired from a planetary gear system (the indispensable part of wind turbine gearbox is directly related to the accuracy of fault diagnosis. The complex operation environment leads to lots of interference signals which are included in the vibration signals. Furthermore, both multiple gears meshing with each other and the differences in transmission rout produce strong nonlinearity in the vibration signals, which makes it difficult to eliminate the noise. This article presents a combined adaptive filter method by taking a delayed signal as reference signal, the Self-Adaptive Noise Cancellation method is adopted to eliminate the white noise. In the meanwhile, by applying Gaussian function to transform the input signal into high-dimension feature-space signal, the kernel least mean square algorithm is used to cancel the nonlinear interference. Effectiveness of the method has been verified by simulation signals and test rig signals. By dealing with simulation signal, the signal-to-noise ratio can be improved around 30 dB (white noise and the amplitude of nonlinear interference signal can be depressed up to 50%. Experimental results show remarkable improvements and enhance gear fault features.
Extended Kalman Filter with a Fuzzy Method for Accurate Battery Pack State of Charge Estimation
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Saeed Sepasi
2015-06-01
Full Text Available As the world moves toward greenhouse gas reduction, there is increasingly active work around Li-ion chemistry-based batteries as an energy source for electric vehicles (EVs, hybrid electric vehicles (HEVs and smart grids. In these applications, the battery management system (BMS requires an accurate online estimation of the state of charge (SOC in a battery pack. This estimation is difficult, especially after substantial battery aging. In order to address this problem, this paper utilizes SOC estimation of Li-ion battery packs using a fuzzy-improved extended Kalman filter (fuzzy-IEKF for Li-ion cells, regardless of their age. The proposed approach introduces a fuzzy method with a new class and associated membership function that determines an approximate initial value applied to SOC estimation. Subsequently, the EKF method is used by considering the single unit model for the battery pack to estimate the SOC for following periods of battery use. This approach uses an adaptive model algorithm to update the model for each single cell in the battery pack. To verify the accuracy of the estimation method, tests are done on a LiFePO4 aged battery pack consisting of 120 cells connected in series with a nominal voltage of 432 V.
Comparative Study of Different Methods for Soot Sensing and Filter Monitoring in Diesel Exhausts
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Markus Feulner
2017-02-01
Full Text Available Due to increasingly tighter emission limits for diesel and gasoline engines, especially concerning particulate matter emissions, particulate filters are becoming indispensable devices for exhaust gas after treatment. Thereby, for an efficient engine and filter control strategy and a cost-efficient filter design, reliable technologies to determine the soot load of the filters and to measure particulate matter concentrations in the exhaust gas during vehicle operation are highly needed. In this study, different approaches for soot sensing are compared. Measurements were conducted on a dynamometer diesel engine test bench with a diesel particulate filter (DPF. The DPF was monitored by a relatively new microwave-based approach. Simultaneously, a resistive type soot sensor and a Pegasor soot sensing device as a reference system measured the soot concentration exhaust upstream of the DPF. By changing engine parameters, different engine out soot emission rates were set. It was found that the microwave-based signal may not only indicate directly the filter loading, but by a time derivative, the engine out soot emission rate can be deduced. Furthermore, by integrating the measured particulate mass in the exhaust, the soot load of the filter can be determined. In summary, all systems coincide well within certain boundaries and the filter itself can act as a soot sensor.
Resistive heater geometry and regeneration method for a diesel particulate filter
Phelps, Amanda; Kirby, Kevin W.; Gregoir, Daniel J.
2011-10-25
One embodiment of the invention includes a diesel particulate filter comprising a first face and a second face; a bottom electrode layer formed over the first face of the diesel particulate filter; a middle resistive layer formed over a portion of the bottom electrode layer; and a top electrode layer formed over a portion of the middle resistive layer.
Wang, Lutao; Xiao, Jun; Chai, Hua
2015-08-01
The successful suppression of clutter arising from stationary or slowly moving tissue is one of the key issues in medical ultrasound color blood imaging. Remaining clutter may cause bias in the mean blood frequency estimation and results in a potentially misleading description of blood-flow. In this paper, based on the principle of general wall-filter, the design process of three classes of filters, infinitely impulse response with projection initialization (Prj-IIR), polynomials regression (Pol-Reg), and eigen-based filters are previewed and analyzed. The performance of the filters was assessed by calculating the bias and variance of a mean blood velocity using a standard autocorrelation estimator. Simulation results show that the performance of Pol-Reg filter is similar to Prj-IIR filters. Both of them can offer accurate estimation of mean blood flow speed under steady clutter conditions, and the clutter rejection ability can be enhanced by increasing the ensemble size of Doppler vector. Eigen-based filters can effectively remove the non-stationary clutter component, and further improve the estimation accuracy for low speed blood flow signals. There is also no significant increase in computation complexity for eigen-based filters when the ensemble size is less than 10.
Comparative Study of Different Methods for Soot Sensing and Filter Monitoring in Diesel Exhausts
Feulner, Markus; Hagen, Gunter; Hottner, Kathrin; Redel, Sabrina; Müller, Andreas; Moos, Ralf
2017-01-01
Due to increasingly tighter emission limits for diesel and gasoline engines, especially concerning particulate matter emissions, particulate filters are becoming indispensable devices for exhaust gas after treatment. Thereby, for an efficient engine and filter control strategy and a cost-efficient filter design, reliable technologies to determine the soot load of the filters and to measure particulate matter concentrations in the exhaust gas during vehicle operation are highly needed. In this study, different approaches for soot sensing are compared. Measurements were conducted on a dynamometer diesel engine test bench with a diesel particulate filter (DPF). The DPF was monitored by a relatively new microwave-based approach. Simultaneously, a resistive type soot sensor and a Pegasor soot sensing device as a reference system measured the soot concentration exhaust upstream of the DPF. By changing engine parameters, different engine out soot emission rates were set. It was found that the microwave-based signal may not only indicate directly the filter loading, but by a time derivative, the engine out soot emission rate can be deduced. Furthermore, by integrating the measured particulate mass in the exhaust, the soot load of the filter can be determined. In summary, all systems coincide well within certain boundaries and the filter itself can act as a soot sensor. PMID:28218700
Novel Campylobacter isolation method using hydrophobic grid membrane filter and semisolid medium.
Valdivieso-Garcia, Alfonso; Harris, Kathleen; Riche, Edward; Campbell, Stephanie; Jarvie, Anne; Popa, Maria; Deckert, Anne; Reid-Smith, Richard; Rahn, Kris
2007-02-01
Culture procedures for isolation of thermophilic campylobacters from food matrices are complex, labor intensive, and time-consuming. Most available methods include the use of antibiotics as selective agents to prevent the growth of competing microflora. A simple procedure for isolation of thermophilic campylobacters after enrichment in Rosef's enrichment broth was developed using a hydrophobic grid membrane filter (HGMF) on semisolid medium (SSM). SSM contains no antibiotics, and the HGMF physically separates Campylobacter from the enrichment broth, allowing isolation based on differential motility. The HGMF-SSM method was compared to the Agriculture and Agri-Food Canada Food Safety Procedures Manual (FSPM-10) method (Isolation of Thermophilic Campylobacters from Fresh Pork, Beef Veal, Poultry and Ready-to-Eat Meat Products), which includes the use of selective antibiotics. During the initial study, after enrichment the HGMF-SSM method yielded pure cultures of campylobacters after 16 to 18 h (overnight) compared with 48 h for the FSPM-10 method. Ninety-four turkey samples collected at local retail stores and 38 frozen pig fecal samples were processed by both methods. Thirty-five samples (26.5%) were positive by the HGMF-SSM method; 24 (18.2%) of these positive samples contained Campylobacter jejuni and 11 (8.3%) contained Campylobacter coli. With the FSPM-10 method, 25 samples (18.9%) were positive: 21 (15.9%) with C. jejuni and 4 (3%) with C. coli. For a subsequent field study, only the HGMF-SSM method was used to isolate Campylobacter from 1,200 chicken samples and 454 turkey samples sold at retail. Analysis of five subisolates from various samples indicated that only one type of Campylobacter was recovered by the HGMF-SSM method, as ascertained by MICs for 10 antimicrobials, sequencing of the short variable region of the flaA gene, and fingerprinting based on amplified fragment length polymorphism. The absence of antibiotics in the SSM may explain the higher
Sinha, Sanjoy K.; Troxel, Andrea B.; Lipsitz, Stuart R.; Sinha, Debajyoti; Fitzmaurice, Garrett M.; Molenberghs, Geert; Ibrahim, Joseph G.
2010-01-01
Summary For analyzing longitudinal binary data with nonignorable and non-monotone missing responses, a full likelihood method is complicated algebraically, and often requires intensive computation, especially when there are many follow-up times. As an alternative, a pseudo-likelihood approach has been proposed in the literature under minimal parametric assumptions. This formulation only requires specification of the marginal distributions of the responses and missing data mechanism, and uses an independence working assumption. However, this estimator can be inefficient for estimating both time-varying and time-stationary effects under moderate to strong within-subject associations among repeated responses. In this article, we propose an alternative estimator, based on a bivariate pseudo-likelihood, and demonstrate in simulations that the proposed method can be much more efficient than the previous pseudo-likelihood obtained under the assumption of independence. We illustrate the method using longitudinal data on CD4 counts from two clinical trials of HIV-infected patients. PMID:21155748
Directory of Open Access Journals (Sweden)
Wang Li
Full Text Available Biomarkers in exhaled breath are useful for respiratory disease diagnosis in human volunteers. Conventional methods that collect non-volatile biomarkers, however, necessitate an extensive dilution and sanitation processes that lowers collection efficiencies and convenience of use. Electret filter emerged in recent decade to collect virus biomarkers in exhaled breath given its simplicity and effectiveness. To investigate the capability of electret filters to collect protein biomarkers, a model that consists of an atomizer that produces protein aerosol and an electret filter that collects albumin and carcinoembryonic antigen-a typical biomarker in lung cancer development- from the atomizer is developed. A device using electret filter as the collecting medium is designed to collect human albumin from exhaled breath of 6 volunteers. Comparison of the collecting ability between the electret filter method and other 2 reported methods is finally performed based on the amounts of albumin collected from human exhaled breath. In conclusion, a decreasing collection efficiency ranging from 17.6% to 2.3% for atomized albumin aerosol and 42% to 12.5% for atomized carcinoembryonic antigen particles is found; moreover, an optimum volume of sampling human exhaled breath ranging from 100 L to 200 L is also observed; finally, the self-designed collecting device shows a significantly better performance in collecting albumin from human exhaled breath than the exhaled breath condensate method (p0.05. In summary, electret filters are potential in collecting non-volatile biomarkers in human exhaled breath not only because it was simpler, cheaper and easier to use than traditional methods but also for its better collecting performance.
Apparatus and method for removing particulate deposits from high temperature filters
Nakaishi, Curtis V.; Holcombe, Norman T.; Micheli, Paul L.
1992-01-01
A combustion of a fuel-air mixture is used to provide a high-temperature and high-pressure pulse of gaseous combustion products for the back-flush cleaning of ceramic filter elements contained in a barrier filter system and utilized to separate particulates from particulate-laden process gases at high temperature and high pressure. The volume of gaseous combustion products provided by the combustion of the fuel-air mixture is preferably divided into a plurality of streams each passing through a sonic orifice and conveyed to the open end of each filter element as a high pressure pulse which passes through the filter elements and dislodges dust cake supported on a surface of the filter element.
Finger-vein image enhancement using a fuzzy-based fusion method with Gabor and Retinex filtering.
Shin, Kwang Yong; Park, Young Ho; Nguyen, Dat Tien; Park, Kang Ryoung
2014-02-17
Because of the advantages of finger-vein recognition systems such as live detection and usage as bio-cryptography systems, they can be used to authenticate individual people. However, images of finger-vein patterns are typically unclear because of light scattering by the skin, optical blurring, and motion blurring, which can degrade the performance of finger-vein recognition systems. In response to these issues, a new enhancement method for finger-vein images is proposed. Our method is novel compared with previous approaches in four respects. First, the local and global features of the vein lines of an input image are amplified using Gabor filters in four directions and Retinex filtering, respectively. Second, the means and standard deviations in the local windows of the images produced after Gabor and Retinex filtering are used as inputs for the fuzzy rule and fuzzy membership function, respectively. Third, the optimal weights required to combine the two Gabor and Retinex filtered images are determined using a defuzzification method. Fourth, the use of a fuzzy-based method means that image enhancement does not require additional training data to determine the optimal weights. Experimental results using two finger-vein databases showed that the proposed method enhanced the accuracy of finger-vein recognition compared with previous methods.
Finger-Vein Image Enhancement Using a Fuzzy-Based Fusion Method with Gabor and Retinex Filtering
Directory of Open Access Journals (Sweden)
Kwang Yong Shin
2014-02-01
Full Text Available Because of the advantages of finger-vein recognition systems such as live detection and usage as bio-cryptography systems, they can be used to authenticate individual people. However, images of finger-vein patterns are typically unclear because of light scattering by the skin, optical blurring, and motion blurring, which can degrade the performance of finger-vein recognition systems. In response to these issues, a new enhancement method for finger-vein images is proposed. Our method is novel compared with previous approaches in four respects. First, the local and global features of the vein lines of an input image are amplified using Gabor filters in four directions and Retinex filtering, respectively. Second, the means and standard deviations in the local windows of the images produced after Gabor and Retinex filtering are used as inputs for the fuzzy rule and fuzzy membership function, respectively. Third, the optimal weights required to combine the two Gabor and Retinex filtered images are determined using a defuzzification method. Fourth, the use of a fuzzy-based method means that image enhancement does not require additional training data to determine the optimal weights. Experimental results using two finger-vein databases showed that the proposed method enhanced the accuracy of finger-vein recognition compared with previous methods.
Papaya Tree Detection with UAV Images Using a GPU-Accelerated Scale-Space Filtering Method
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Hao Jiang
2017-07-01
Full Text Available The use of unmanned aerial vehicles (UAV can allow individual tree detection for forest inventories in a cost-effective way. The scale-space filtering (SSF algorithm is commonly used and has the capability of detecting trees of different crown sizes. In this study, we made two improvements with regard to the existing method and implementations. First, we incorporated SSF with a Lab color transformation to reduce over-detection problems associated with the original luminance image. Second, we ported four of the most time-consuming processes to the graphics processing unit (GPU to improve computational efficiency. The proposed method was implemented using PyCUDA, which enabled access to NVIDIA’s compute unified device architecture (CUDA through high-level scripting of the Python language. Our experiments were conducted using two images captured by the DJI Phantom 3 Professional and a most recent NVIDIA GPU GTX1080. The resulting accuracy was high, with an F-measure larger than 0.94. The speedup achieved by our parallel implementation was 44.77 and 28.54 for the first and second test image, respectively. For each 4000 × 3000 image, the total runtime was less than 1 s, which was sufficient for real-time performance and interactive application.
Energy Technology Data Exchange (ETDEWEB)
Baiao, D.; Medina, F.; Ochando, M.; Varandas, C.
2009-07-01
The TJ-II plasma soft X-ray emission was studied in order to establish an adequate setup for an electron temperature diagnostic suitable for high density, with spatial and temporal resolutions, based on the two-filters method. The preliminary experimental results reported were obtained with two diagnostics (an X-ray PHA based on a Ge detector and a tomography system) already installed in TJ-II stellarator. These results lead to the conclusion that the two-filters method was a suitable option for an electron temperature diagnostic for high-density plasmas in TJ-II. We present the design and fi rst results obtained with a prototype for the measurement of electron temperature in TJ-II plasmas heated with energetic neutral beams. This system consists in two AXUV20A detectors which measure the soft X-ray plasma emissivity trough beryllium filters of different thickness. From the two-filters technique it is possible to estimate the electron temperature. The analyses carried out allowed concluding which filter thicknesses are most suited for TJ-II plasmas, and enhanced the need of a computer code to simulate signals and plasma compositions. (Author) 7 refs.
Semiparametric approach for non-monotone missing covariates in a parametric regression model
Sinha, Samiran
2014-02-26
Missing covariate data often arise in biomedical studies, and analysis of such data that ignores subjects with incomplete information may lead to inefficient and possibly biased estimates. A great deal of attention has been paid to handling a single missing covariate or a monotone pattern of missing data when the missingness mechanism is missing at random. In this article, we propose a semiparametric method for handling non-monotone patterns of missing data. The proposed method relies on the assumption that the missingness mechanism of a variable does not depend on the missing variable itself but may depend on the other missing variables. This mechanism is somewhat less general than the completely non-ignorable mechanism but is sometimes more flexible than the missing at random mechanism where the missingness mechansim is allowed to depend only on the completely observed variables. The proposed approach is robust to misspecification of the distribution of the missing covariates, and the proposed mechanism helps to nullify (or reduce) the problems due to non-identifiability that result from the non-ignorable missingness mechanism. The asymptotic properties of the proposed estimator are derived. Finite sample performance is assessed through simulation studies. Finally, for the purpose of illustration we analyze an endometrial cancer dataset and a hip fracture dataset.
Semiparametric approach for non-monotone missing covariates in a parametric regression model.
Sinha, Samiran; Saha, Krishna K; Wang, Suojin
2014-06-01
Missing covariate data often arise in biomedical studies, and analysis of such data that ignores subjects with incomplete information may lead to inefficient and possibly biased estimates. A great deal of attention has been paid to handling a single missing covariate or a monotone pattern of missing data when the missingness mechanism is missing at random. In this article, we propose a semiparametric method for handling non-monotone patterns of missing data. The proposed method relies on the assumption that the missingness mechanism of a variable does not depend on the missing variable itself but may depend on the other missing variables. This mechanism is somewhat less general than the completely non-ignorable mechanism but is sometimes more flexible than the missing at random mechanism where the missingness mechansim is allowed to depend only on the completely observed variables. The proposed approach is robust to misspecification of the distribution of the missing covariates, and the proposed mechanism helps to nullify (or reduce) the problems due to non-identifiability that result from the non-ignorable missingness mechanism. The asymptotic properties of the proposed estimator are derived. Finite sample performance is assessed through simulation studies. Finally, for the purpose of illustration we analyze an endometrial cancer dataset and a hip fracture dataset.
Development of gel-filter method for high enrichment of low-molecular weight proteins from serum.
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Lingsheng Chen
Full Text Available The human serum proteome has been extensively screened for biomarkers. However, the large dynamic range of protein concentrations in serum and the presence of highly abundant and large molecular weight proteins, make identification and detection changes in the amount of low-molecular weight proteins (LMW, molecular weight ≤ 30kDa difficult. Here, we developed a gel-filter method including four layers of different concentration of tricine SDS-PAGE-based gels to block high-molecular weight proteins and enrich LMW proteins. By utilizing this method, we identified 1,576 proteins (n = 2 from 10 μL serum. Among them, 559 (n = 2 proteins belonged to LMW proteins. Furthermore, this gel-filter method could identify 67.4% and 39.8% more LMW proteins than that in representative methods of glycine SDS-PAGE and optimized-DS, respectively. By utilizing SILAC-AQUA approach with labeled recombinant protein as internal standard, the recovery rate for GST spiked in serum during the treatment of gel-filter, optimized-DS, and ProteoMiner was 33.1 ± 0.01%, 18.7 ± 0.01% and 9.6 ± 0.03%, respectively. These results demonstrate that the gel-filter method offers a rapid, highly reproducible and efficient approach for screening biomarkers from serum through proteomic analyses.
More data, less information? Potential for nonmonotonic information growth using GEE.
Shoben, Abigail B; Rudser, Kyle D; Emerson, Scott S
2017-01-01
Statistical intuition suggests that increasing the total number of observations available for analysis should increase the precision with which parameters can be estimated. Such monotonic growth of statistical information is of particular importance when data are analyzed sequentially, such as in confirmatory clinical trials. However, monotonic information growth is not always guaranteed, even when using a valid, but inefficient estimator. In this article, we demonstrate the theoretical possibility of nonmonotonic information growth when using generalized estimating equations (GEE) to estimate a slope and provide intuition for why this possibility exists. We use theoretical and simulation-based results to characterize situations that may result in nonmonotonic information growth. Nonmonotonic information growth is most likely to occur when (1) accrual is fast relative to follow-up on each individual, (2) correlation among measurements from the same individual is high, and (3) measurements are becoming more variable further from randomization. In situations that may lead to nonmonotonic information growth, study designers should plan interim analyses to avoid situations most likely to result in nonmonotonic information growth.
地震资料数据处理中的形态滤波去噪方法%Method for Morphological Filtering in Seismic Data Processing
Institute of Scientific and Technical Information of China (English)
李青; 王润秋; 黄文锋; 郑桂娟
2005-01-01
A new method is introduced to suppress the noise in seismic data processing. Based on the subtle difference in shape between the noise and the actual signal, we introduce morphologic filtering into seismic data processing. From the shape and the S/N we can see that the effect of morphologic filtering is superior to other methods like id-value filtering, neighbor average filtering, etc. The SNR of the signal after morphological filtering is comparatively great. In addition, the precision of the seismic data after morphological filtering is high. The characteristics of the actual signal, such as frequency and amplitude, are preserved. We give an example of the real seismic data processing using morphological filtering, in which the actual signal is retained, while the random high intensity noise was removed.
Noise Image Filtering Method Based on Simplified PCNN%基于简化PCNN的脉冲噪声滤波
Institute of Scientific and Technical Information of China (English)
郭旭展; 姚建峰
2015-01-01
基于脉冲耦合神经网络，提出了一种有效的脉冲噪声图像滤波算法。利用 PCNN相似群神经元同步发放脉冲的特性检测噪声点，并利用中值滤波对噪声点进行滤波。仿真表明，该方法对不同强度的噪声图像均体现了较好的滤波性能，在去噪效果和运行效率上同其它方法相比具有明显优势。%Based on Pulse Coupled Neural networks ,an effective pulse noise image filtering method is proposed .Synchro‐nous pulses were burst by using the similar groups of neurons in a PCNN ,whereby the noise pixels are detected;then me‐dian filtering method filtered the noise in a noise image .Simulation results show that the proposed method has excellent filtering performance for the noise images of different noise intensity ,the proposed method has remarkable superiority over other ones in both simulation performance and running efficiency .
DEFF Research Database (Denmark)
Drews, Martin; Lauritzen, Bent; Madsen, Henrik
2005-01-01
parameters, and the observables are linked to the state variables through a static measurement equation. The method is analysed for three simple state space models using experimental data obtained at a nuclear research reactor. Compared to direct measurements of the atmospheric dispersion, the Kalman filter...... estimates are found to agree well with the measured parameters, provided that the radiation measurements are spread out in the cross-wind direction. For less optimal detector placement it proves difficult to distinguish variations in the source term and plume height; yet the Kalman filter yields consistent...... scheme are outlined, to account for realistic accident scenarios....
A FBG pulse wave demodulation method based on PCF modal interference filter
Zhang, Cheng; Xu, Shan; Shen, Ziqi; Zhao, Junfa; Miao, Changyun; Bai, Hua
2016-10-01
Fiber optic sensor embedded in textiles has been a new direction of researching smart wearable technology. Pulse signal which is generated by heart beat contains vast amounts of physio-pathological information about the cardiovascular system. Therefore, the research for textile-based fiber optic sensor which can detect pulse wave has far-reaching effects on early discovery and timely treatment of cardiovascular diseases. A novel wavelength demodulation method based on photonic crystal fiber (PCF) modal interference filter is proposed for the purpose of developing FBG pulse wave sensing system embedded in smart clothing. The mechanism of the PCF modal interference and the principle of wavelength demodulation based on In-line Mach-Zehnder interferometer (In-line MZI) are analyzed in theory. The fabricated PCF modal interferometer has the advantages of good repeatability and low temperature sensitivity of 3.5pm/°C from 25°C to 60°C. The designed demodulation system can achieve linear demodulation in the range of 2nm, with the wavelength resolution of 2.2pm and the wavelength sensitivity of 0.055nm-1. The actual experiments' result indicates that the pulse wave can be well detected by this demodulation method, which is in accordance with the commercial demodulation instrument (SM130) and more sensitive than the traditional piezoelectric pulse sensor. This demodulation method provides important references for the research of smart clothing based on fiber grating sensor embedded in textiles and accelerates the developments of wearable fiber optic sensors technology.
Handling Out-of-Sequence Data: Kalman Filter Methods or Statistical Imputation?
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Bhekisipho Twala
2010-01-01
Full Text Available The issue of handling sensor measurements data over single and multiple lag delays also known as outof-sequence measurement (OOSM has been considered. It is argued that this problem can also be addressed using model-based imputation strategies and their application in comparison to Kalman filter (KF-based approaches for a multi-sensor tracking prediction problem has also been demonstrated. The effectiveness of two model-based imputation procedures against five OOSM methods was investigated in Monte Carlo simulation experiments. The delayed measurements were either incorporated (or fused at the time these were finally available (using OOSM methods or imputed in a random way with higher probability of delays for multiple lags and lower probability of delays for a single lag (using single or multiple imputation. For single lag, estimates of target tracking computed from the observed data and those based on a data set in which the delayed measurements were imputed were equally unbiased; however, the KF estimates obtained using the Bayesian framework (BF-KF were more precise. When the measurements were delayed in a multiple lag fashion, there were significant differences in bias or precision between multiple imputation (MI and OOSM methods, with the former exhibiting a superior performance at nearly all levels of probability of measurement delay and range of manoeuvring indices. Researchers working on sensor data are encouraged to take advantage of software to implement delayed measurements using MI, as estimates of tracking are more precise and less biased in the presence of delayed multi-sensor data than those derived from an observed data analysis approach.Defence Science Journal, 2010, 60(1, pp.87-99, DOI:http://dx.doi.org/10.14429/dsj.60.115
A Center-Median Filtering Method for Detection of Temporal Variation in Coronal Images
Plowman, Joseph
2015-01-01
Events in the solar corona are often widely separated in their timescales, which can allow them to be identified when they would otherwise be confused with emission from other sources in the corona. Methods for cleanly separating such events based on their timescales are thus desirable for research in the field. This paper develops a technique for identifying time-varying signals in solar coronal image sequences which is based on a per-pixel running median filter and an understanding of photon-counting statistics. Example applications to 'EIT Waves' and small-scale dynamics are shown, both using data from the 193 Angstrom channel on AIA. The technique is found to discriminate EIT Waves more cleanly than the running and base difference techniques most commonly used. It is also demonstrated that there is more signal in the data than is commonly appreciated, finding that the waves can be traced to the edge of the AIA field of view when the data are rebinned to increase the signal-to-noise ratio.
Directory of Open Access Journals (Sweden)
Hong-jun BAO
2011-03-01
Full Text Available A real-time channel flood forecast model was developed to simulate channel flow in plain rivers based on the dynamic wave theory. Taking into consideration channel shape differences along the channel, a roughness updating technique was developed using the Kalman filter method to update Manning’s roughness coefficient at each time step of the calculation processes. Channel shapes were simplified as rectangles, triangles, and parabolas, and the relationships between hydraulic radius and water depth were developed for plain rivers. Based on the relationship between the Froude number and the inertia terms of the momentum equation in the Saint-Venant equations, the relationship between Manning’s roughness coefficient and water depth was obtained. Using the channel of the Huaihe River from Wangjiaba to Lutaizi stations as a case, to test the performance and rationality of the present flood routing model, the original hydraulic model was compared with the developed model. Results show that the stage hydrographs calculated by the developed flood routing model with the updated Manning’s roughness coefficient have a good agreement with the observed stage hydrographs. This model performs better than the original hydraulic model.
A center-median filtering method for detection of temporal variation in coronal images
Directory of Open Access Journals (Sweden)
Plowman Joseph
2016-01-01
Full Text Available Events in the solar corona are often widely separated in their timescales, which can allow them to be identified when they would otherwise be confused with emission from other sources in the corona. Methods for cleanly separating such events based on their timescales are thus desirable for research in the field. This paper develops a technique for identifying time-varying signals in solar coronal image sequences which is based on a per-pixel running median filter and an understanding of photon-counting statistics. Example applications to “EIT waves” (named after EIT, the EUV Imaging Telescope on the Solar and Heliospheric Observatory and small-scale dynamics are shown, both using 193 Å data from the Atmospheric Imaging Assembly (AIA on the Solar Dynamics Observatory. The technique is found to discriminate EIT waves more cleanly than the running and base difference techniques most commonly used. It is also demonstrated that there is more signal in the data than is commonly appreciated, finding that the waves can be traced to the edge of the AIA field of view when the data are rebinned to increase the signal-to-noise ratio.
Xue, L.; Dai, C.; Zhang, D.; Guadagnini, A.
2015-12-01
It is critical to predict contaminant plume in an aquifer under uncertainty, which can help assess environmental risk and design rational management strategies. An accurate prediction of contaminant plume requires the collection of data to help characterize the system. Due to the limitation of financial resources, ones should estimate the expectative value of data collected from each optional monitoring scheme before carried out. Data-worth analysis is believed to be an effective approach to identify the value of the data in some problems, which quantifies the uncertainty reduction assuming that the plausible data has been collected. However, it is difficult to apply the data-worth analysis to a dynamic simulation of contaminant transportation model owning to its requirement of large number of inverse-modeling. In this study, a novel efficient data-worth analysis framework is proposed by developing the Probabilistic Collocation Method based Ensemble Kalman Filter (PCKF). The PCKF constructs polynomial chaos expansion surrogate model to replace the original complex numerical model. Consequently, the inverse modeling can perform on the proxy rather than the original model. An illustrative example, considering the dynamic change of the contaminant concentration, is employed to demonstrate the proposed approach. The Results reveal that schemes with different sampling frequencies, monitoring networks location, prior data content will have significant impact on the uncertainty reduction of the estimation of contaminant plume. Our proposition is validated to provide the reasonable value of data from various schemes.
MRI Mammogram Image Segmentation using NCut method and Genetic Algorithm with partial filters
Directory of Open Access Journals (Sweden)
Pitchumani Angayarkanni
2011-01-01
Full Text Available Cancer is one of the most common leading deadly diseases which affect men and women around the world. Among the cancer diseases, breast cancer is especially a concern in women. It has become a major health problem in developed and developing countries over the past 50 years and the incidence has increased in recent years. Recent trends in digital image processing are CAD systems, which are computerized tools designed to assist radiologists. Most of these systems are used for automatic detection of abnormalities. However, recent studies have shown that their sensitivity is significantly decreased as the density of breast increases. In this paper , the proposed algorithm uses partial filters to enhance the images and the Ncut method is applied to segment the malignant and benign regions , further genetic algorithm is applied to identify the nipple position followed by bilateral subtraction of the left and the right breast image to cluster the cancerous and non cancerous regions. The system is trained using Back Propagation Neural Network algorithm. Computational efficiency and accuracy of the proposed system are evaluated based on the Frequency Receiver Operating Characteristic curve(FROC. The algorithm are tested on 161 pairs of digitized mammograms from MIAS database. The Receiver Operating Characteristic curve leads to 99.987% accuracy in detection of cancerous masses.
The Prediction Approach for Periodontitis Using Collaborative Filtering Method in Big Data
Directory of Open Access Journals (Sweden)
SULAIGAL FEMINA.A
2016-05-01
Full Text Available Big data is a term for data sets that are so large or complex that traditional data processing applications are inadequate. We have proposed „the prediction approach‟ in big data which is usually based totally at the decision making or clinical acumen aspect of a Dentist. Collaborative filtering is a „facts Mining method‟ in which data is fed into the machine which analysis it using certain parameters and offer resultant outcomes which helps in the future prediction of the disease, which in this case is Periodontitis. This will help in making decisions by examining or analyzing the whole disorder and plan the treatment to prevent its occurrence in future. It is by far the most specialized and latest technology used in Dentistry to prevent the disease occurrence in advance before it arise and create treatment strategies for future prevention of the disease. This method could be tested with the huge collection of ancient statistics of dental diseases to check the effectiveness of the technique and based on the generated end result; precision of prediction can be executed in future.
Electron Energy Resolution of the ATLAS TILECAL Modules with Fit Filter Method (July 2002 test beam)
Kulchitskii, Yu A; Vinogradov, V B
2006-01-01
The constructed ATLAS detector at the LHC will have the great physics discovery potential, in particular in the detection of a heavy Higgs boson. Calorimeters will play a crucial role in it. It is necessary to have confidence that the calorimeters will perform as expected. With the aim of understanding of performance of the ATLAS Tile hadronic calorimeter to electrons 12\\% of modules have been exposed in electron beams with various energies by three possible ways: cell-scan at $\\theta =20^o$ at the centers of the front face cells, $\\eta$-scan and tilerow scan at $\\theta = 90^o$ for the module side cells. We have extracted the electron energy resolutions of the $EBM-$ (ANL-44), $EBM+$ (IFA-42) and $BM$ (JINR-55) Modules of the ATLAS Tile Calorimeter at energies E = 10, 20, 50, 100 and 180 GeV and $\\theta = 20^o$ and $90^o $ and $\\eta$ scan from the July 2002 testbeam run data using the fit filter method of the PMT signal reconstruction. We have determined the statistical and constant terms for the electron ene...
Kulchitskii, Yu A; Vinogradov, V B
2005-01-01
The constructed ATLAS detector at the LHC will have the great physics discovery potential, in particular in the detection of a heavy Higgs boson. Calorimeters will play a crucial role in it. It is necessary to have confidence that the calorimeters will perform as expected. With the aim of understanding of performance of the ATLAS Tile hadronic calorimeter to electrons 12\\% of modules have been exposed in electron beams with various energies by three possible ways: cell-scan at $\\theta =20^o$ at the centers of the front face cells, $\\eta$-scan and tilerow scan at $\\theta = 90^o$ for the module side cells. We have extracted the electron energy resolutions of the $EBM-$ (ANL-44), $EBM+$ (IFA-42) and $BM$ (JINR-55) Modules of the ATLAS Tile Calorimeter at energies E = 10, 20, 50, 100 and 180 GeV and $\\theta = 20^o$ and $90^o $ and $\\eta$ scan from the July 2002 testbeam run data using the flat filter method of the PMT signal reconstruction. We have determined the statistical and constant terms for the electron en...
Energy Calibration of the TILECAL Modules with the Fit Filter Method (July 2002 Test Beam Data)
Kulchitskii, Yu A; Vinogradov, V B
2005-01-01
The constructed ATLAS detector at the LHC will have the great physics discovery potential, in particular in the detection of a heavy Higgs boson. Calorimeters will play a crucial role in it. The important question of calorimetry is the calibration in the electromagnetic energy scale. With the aim of establishing of this scale and understanding of performance of the ATLAS Tile hadronic calorimeter to electrons 12\\% of modules have been exposed in electron beams with various energies by three possible ways: cell-scan at $\\theta =20^o$ at the centers of the front face cells, $\\eta$-scan and tilerow scan at $\\theta = 90^o$ for the module side cells. Our work is devoted to the determination of the electromagnetic energy calibration constants of the EBM$-$ (ANL-44), EBM$+$ (IFA-42), BM (JINR-55) TILECAL modules at energies E = 10, 20, 50, 100 and 180 GeV and $\\theta = 20^o$ and $90^o$ and $\\eta$ scans on the basis of the July 2002 testbeam run data using the fit filter method of the PMT signal reconstruction. The o...
[Removal pathway and influence factors of hydroponic bio-filter method for nitrogen and phosphorus].
Li, Xian-ning; Song, Hai-liang; Lü, Xi-wu; Osamu, Nishimura; Yuhei, Inamori
2007-05-01
Study was made on the use of hydroponic bio-filter method (HBFM) for eutrophic surface water. Results show that HBFM can remove 16.8% of TN and 30.8% of TP at the hydraulic loading rate (HLR) of 3.0 m3/(m2 x d). The removal loading rate of TN and TP can accordingly reach 1.0 and 0.1 g/(m2 x d) respectively. The sedimentation of particulate nitrogen and particulate phosphorus plays a major role in nitrogen and phosphorus removal, and its contribution is 62.2% and 75.9% respectively. The optimal HLR of HBFM ranges from 3.0 to 4.0 m3/(m x d). The intension of secateur for Nasturtium officinale has some effect on its uptake rate, thus the length of cut when harvesting should be less than 10 cm. The harvesting frequency of once a month for Nasturtium officinale has no effect on nitrogen and phosphorus removal of HBFM.
Comparison of two quantitative fit-test methods using N95 filtering facepiece respirators.
Sietsema, Margaret; Brosseau, Lisa M
2016-08-01
Current regulations require annual fit testing before an employee can wear a respirator during work activities. The goal of this research is to determine whether respirator fit measured with two TSI Portacount instruments simultaneously sampling ambient particle concentrations inside and outside of the respirator facepiece is similar to fit measured during an ambient aerosol condensation nuclei counter quantitative fit test. Sixteen subjects (ten female; six male) were recruited for a range of facial sizes. Each subject donned an N95 filtering facepiece respirator, completed two fit tests in random order (ambient aerosol condensation nuclei counter quantitative fit test and two-instrument real-time fit test) without removing or adjusting the respirator between tests. Fit tests were compared using Spearman's rank correlation coefficients. The real-time two-instrument method fit factors were similar to those measured with the single-instrument quantitative fit test. The first four exercises were highly correlated (r > 0.7) between the two protocols. Respirator fit was altered during the talking or grimace exercise, both of which involve facial movements that could dislodge the facepiece. Our analyses suggest that the new real-time two-instrument methodology can be used in future studies to evaluate fit before and during work activities.
Meng, Xi; Nguyen, Bao D; Ridge, Clark; Shaka, A J
2009-01-01
High-dimensional (HD) NMR spectra have poorer digital resolution than low-dimensional (LD) spectra, for a fixed amount of experiment time. This has led to "reduced-dimensionality" strategies, in which several LD projections of the HD NMR spectrum are acquired, each with higher digital resolution; an approximate HD spectrum is then inferred by some means. We propose a strategy that moves in the opposite direction, by adding more time dimensions to increase the information content of the data set, even if only a very sparse time grid is used in each dimension. The full HD time-domain data can be analyzed by the filter diagonalization method (FDM), yielding very narrow resonances along all of the frequency axes, even those with sparse sampling. Integrating over the added dimensions of HD FDM NMR spectra reconstitutes LD spectra with enhanced resolution, often more quickly than direct acquisition of the LD spectrum with a larger number of grid points in each of the fewer dimensions. If the extra-dimensions do not appear in the final spectrum, and are used solely to boost information content, we propose the moniker hidden-dimension NMR. This work shows that HD peaks have unmistakable frequency signatures that can be detected as single HD objects by an appropriate algorithm, even though their patterns would be tricky for a human operator to visualize or recognize, and even if digital resolution in an HD FT spectrum is very coarse compared with natural line widths.
Fault detection method for railway wheel flat using an adaptive multiscale morphological filter
Li, Yifan; Zuo, Ming J.; Lin, Jianhui; Liu, Jianxin
2017-02-01
This study explores the capacity of the morphology analysis for railway wheel flat fault detection. A dynamic model of vehicle systems with 56 degrees of freedom was set up along with a wheel flat model to calculate the dynamic responses of axle box. The vehicle axle box vibration signal is complicated because it not only contains the information of wheel defect, but also includes track condition information. Thus, how to extract the influential features of wheels from strong background noise effectively is a typical key issue for railway wheel fault detection. In this paper, an algorithm for adaptive multiscale morphological filtering (AMMF) was proposed, and its effect was evaluated by a simulated signal. And then this algorithm was employed to study the axle box vibration caused by wheel flats, as well as the influence of track irregularity and vehicle running speed on diagnosis results. Finally, the effectiveness of the proposed method was verified by bench testing. Research results demonstrate that the AMMF extracts the influential characteristic of axle box vibration signals effectively and can diagnose wheel flat faults in real time.
A METHOD FOR RECORDING AND VIEWING STEREOSCOPIC IMAGES IN COLOUR USING MULTICHROME FILTERS
DEFF Research Database (Denmark)
2000-01-01
differences prescribed by the stereoscopic principle and supplementing the colour perception. For selecting the filters, the invention suggests an auxiliary test. For encoding the stereograms, the invention suggests a special process of channel separation and replacement. For colour correction...
A FILTER-TRUST-REGION METHOD FOR LC1 UNCONSTRAINED OPTIMIZATION AND ITS GLOBAL CONVERGENCE
Institute of Scientific and Technical Information of China (English)
Zhenghao Yang; Wenyu Sun; Chuangyin Dang
2008-01-01
In this paper we present a filter-trust-region algorithm for solving LC1 unconstrained optimization problems which uses the second Dini upper directional derivative.We establish the global convergence of the algorithm under reasonable assumptions.
National Research Council Canada - National Science Library
Mikhail Lvovich Nemchikov; Alexander Nicolaevich Kozlov; Konstantin Igorevich Gryadunov; Anton Mihailovich Meleshnikov
2017-01-01
... of NGOs "Unit", which has been removed from the supply line TC-1 aviation fuel tank farm from the State Reserve in the refueling tank farm "Vnukovo" and the filter control of Velcon company brand...
An Efficient Method for Extracting Features from Blurred Fingerprints Using Modified Gabor Filter
Directory of Open Access Journals (Sweden)
R.Vinothkanna
2012-09-01
Full Text Available Biometrics is the science and technology of measuring and analyzing biological data. In information technology, biometrics refers to technologies that measure and analyze human body characteristics, such as DNA, fingerprints, eye retinas and irises, voice patterns, facial patterns and hand measurements for authentication purposes. Fingerprint is one of the most developed biometrics, with more history, research and design. Fingerprint recognition identifies people by using the impressions made by the minute ridge formations or patterns found on the fingertips. The extraction of features from blurred or unclear fingerprints becomes difficult. So instead of ridges we tried to extract valleys from same images, because fingerprints consist of both ridges and valleys as its features. We found some good results for valley extraction with different filters including Gabor filter. So in this paper we modified the Gabor filter to reduce the time consumption and also for extraction of more valleys than Gabor filter.
Energy Technology Data Exchange (ETDEWEB)
Chisvert, Alberto, E-mail: alberto.chisvert@uv.es [Departamento de Quimica Analitica, Facultad de Quimica, Universitat de Valencia, Doctor Moliner St. 50, 46100 Burjassot, Valencia (Spain); Leon-Gonzalez, Zacarias [Unidad Analitica, Instituto de Investigacion Sanitaria Fundacion Hospital La Fe, 46009 Valencia (Spain); Tarazona, Isuha; Salvador, Amparo [Departamento de Quimica Analitica, Facultad de Quimica, Universitat de Valencia, Doctor Moliner St. 50, 46100 Burjassot, Valencia (Spain); Giokas, Dimosthenis [Laboratory of Analytical Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina (Greece)
2012-11-08
Highlights: Black-Right-Pointing-Pointer Papers describing the determination of UV filters in fluids and tissues are reviewed. Black-Right-Pointing-Pointer Matrix complexity and low amounts of analytes require effective sample treatments. Black-Right-Pointing-Pointer The published papers do not cover the study of all the substances allowed as UV filters. Black-Right-Pointing-Pointer New analytical methods for UV filters determination in these matrices are encouraged. - Abstract: Organic UV filters are chemical compounds added to cosmetic sunscreen products in order to protect users from UV solar radiation. The need of broad-spectrum protection to avoid the deleterious effects of solar radiation has triggered a trend in the cosmetic market of including these compounds not only in those exclusively designed for sun protection but also in all types of cosmetic products. Different studies have shown that organic UV filters can be absorbed through the skin after topical application, further metabolized in the body and eventually excreted or bioaccumulated. These percutaneous absorption processes may result in various adverse health effects, such as genotoxicity caused by the generation of free radicals, which can even lead to mutagenic or carcinogenic effects, and estrogenicity, which is associated with the endocrine disruption activity caused by some of these compounds. Due to the absence of official monitoring protocols, there is a demand for analytical methods that enable the determination of UV filters in biological fluids and tissues in order to retrieve more information regarding their behavior in the human body and thus encourage the development of safer cosmetic formulations. In view of this demand, there has recently been a noticeable increase in the development of sensitive and selective analytical methods for the determination of UV filters and their metabolites in biological fluids (i.e., urine, plasma, breast milk and semen) and tissues. The complexity of
Research on a Lamb Wave and Particle Filter-Based On-Line Crack Propagation Prognosis Method.
Chen, Jian; Yuan, Shenfang; Qiu, Lei; Cai, Jian; Yang, Weibo
2016-03-03
Prognostics and health management techniques have drawn widespread attention due to their ability to facilitate maintenance activities based on need. On-line prognosis of fatigue crack propagation can offer information for optimizing operation and maintenance strategies in real-time. This paper proposes a Lamb wave-particle filter (LW-PF)-based method for on-line prognosis of fatigue crack propagation which takes advantages of the possibility of on-line monitoring to evaluate the actual crack length and uses a particle filter to deal with the crack evolution and monitoring uncertainties. The piezoelectric transducers (PZTs)-based active Lamb wave method is adopted for on-line crack monitoring. The state space model relating to crack propagation is established by the data-driven and finite element methods. Fatigue experiments performed on hole-edge crack specimens have validated the advantages of the proposed method.
Research on a Lamb Wave and Particle Filter-Based On-Line Crack Propagation Prognosis Method
Directory of Open Access Journals (Sweden)
Jian Chen
2016-03-01
Full Text Available Prognostics and health management techniques have drawn widespread attention due to their ability to facilitate maintenance activities based on need. On-line prognosis of fatigue crack propagation can offer information for optimizing operation and maintenance strategies in real-time. This paper proposes a Lamb wave-particle filter (LW-PF-based method for on-line prognosis of fatigue crack propagation which takes advantages of the possibility of on-line monitoring to evaluate the actual crack length and uses a particle filter to deal with the crack evolution and monitoring uncertainties. The piezoelectric transducers (PZTs-based active Lamb wave method is adopted for on-line crack monitoring. The state space model relating to crack propagation is established by the data-driven and finite element methods. Fatigue experiments performed on hole-edge crack specimens have validated the advantages of the proposed method.
A New Design Method for the Passive Damped LCL and LLCL Filter-Based Single-Phase Grid-Tied Inverter
DEFF Research Database (Denmark)
Wu, Weimin; He, Yuanbin; Tang, Tianhao
2013-01-01
scheme with low power loss for the LLCL filter. Also, a simple engineering design criterion is proposed to find the optimized damping resistor value, which is both effective for the LCL filter and the LLCL filter. The control analysis and the power loss comparison for different filter cases are given....... All these are verified through the experiments on a 2-kW single-phase grid-tied inverter prototype using proportional resonant controllers. It is concluded that, compared with the LCL filter, the proposed passive damped LLCL filter can not only save the total filter inductance and reduce the volume...... control challenges. An active or a passive damping measure can be adopted to suppress the possible resonances between the grid and the inverter. For an application with a stiff grid, a passive damping method is often preferred for its simpleness and low cost. This paper introduces a new passive damping...
Search for scalar-tensor gravity theories with a non-monotonic time evolution of the speed-up factor
Energy Technology Data Exchange (ETDEWEB)
Navarro, A [Dept Fisica, Universidad de Murcia, E30071-Murcia (Spain); Serna, A [Dept Fisica, Computacion y Comunicaciones, Universidad Miguel Hernandez, E03202-Elche (Spain); Alimi, J-M [Lab. de l' Univers et de ses Theories (LUTH, CNRS FRE2462), Observatoire de Paris-Meudon, F92195-Meudon (France)
2002-08-21
We present a method to detect, in the framework of scalar-tensor gravity theories, the existence of stationary points in the time evolution of the speed-up factor. An attractive aspect of this method is that, once the particular scalar-tensor theory has been specified, the stationary points are found through a simple algebraic equation which does not contain any integration. By applying this method to the three classes of scalar-tensor theories defined by Barrow and Parsons, we have found several new cosmological models with a non-monotonic evolution of the speed-up factor. The physical interest of these models is that, as previously shown by Serna and Alimi, they predict the observed primordial abundance of light elements for a very wide range of baryon density. These models are then consistent with recent CMB and Lyman-{alpha} estimates of the baryon content of the universe.
A pathway EM-algorithm for estimating vaccine efficacy with a non-monotone validation set.
Yang, Yang; Halloran, M Elizabeth; Chen, Yanjun; Kenah, Eben
2014-09-01
Here, we consider time-to-event data where individuals can experience two or more types of events that are not distinguishable from one another without further confirmation, perhaps by laboratory test. The event type of primary interest can occur only once. The other types of events can recur. If the type of a portion of the events is identified, this forms a validation set. However, even if a random sample of events are tested, confirmations can be missing nonmonotonically, creating uncertainty about whether an individual is still at risk for the event of interest. For example, in a study to estimate efficacy of an influenza vaccine, an individual may experience a sequence of symptomatic respiratory illnesses caused by various pathogens over the season. Often only a limited number of these episodes are confirmed in the laboratory to be influenza-related or not. We propose two novel methods to estimate covariate effects in this survival setting, and subsequently vaccine efficacy. The first is a pathway expectation-maximization (EM) algorithm that takes into account all pathways of event types in an individual compatible with that individual's test outcomes. The pathway EM iteratively estimates baseline hazards that are used to weight possible event types. The second method is a non-iterative pathway piecewise validation method that does not estimate the baseline hazards. These methods are compared with a previous simpler method. Simulation studies suggest mean squared error is lower in the efficacy estimates when the baseline hazards are estimated, especially at higher hazard rates. We use the pathway EM-algorithm to reevaluate the efficacy of a trivalent live-attenuated influenza vaccine during the 2003-2004 influenza season in Temple-Belton, Texas, and compare our results with a previously published analysis. © 2014, The International Biometric Society.
Directory of Open Access Journals (Sweden)
Kohei Arai
2013-06-01
Full Text Available Category decomposition method based on matched filter for un-mixing of mixed pixels: mixels which are acquired with spaceborne based hyperspectral radiometers is proposed. Through simulation studies with simulated mixed pixels which are created with spectral reflectance data derived from USGS spectral library as well as actual airborne based hyperspectral radiometer imagery data, it is found that the proposed method works well with acceptable decomposition accuracy.
Beasley, Amy; Belanger, Scott E; Otter, Ryan R
2015-06-01
Tools exist to evaluate large ecotoxicity databases for risk assessment purposes, but these tools are less useful for alternative analytical purposes. In the present study, the authors developed the Stepwise Information-Filtering Tool (SIFT), a strategic method to select relevant, reliable data from a large ecotoxicity database; demonstrated utility in a case study of chronic toxicity data for statistical endpoint comparison purposes; and evaluated SIFT by comparison with 2 existing data evaluation methods.
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
In this paper, we propose a smoothing algorithm for solving the monotone symmetric cone complementarity problems (SCCP for short) with a nonmonotone line search. We show that the nonmonotone algorithm is globally convergent under an assumption that the solution set of the problem concerned is nonempty. Such an assumption is weaker than those given in most existing algorithms for solving optimization problems over symmetric cones. We also prove that the solution obtained by the algorithm is a maximally complementary solution to the monotone SCCP under some assumptions.
Non-monotonic dynamics and crosstalk in signaling pathways and their implications for pharmacology
van Wijk, Roeland; Tans, Sander J.; Wolde, Pieter Rein Ten; Mashaghi, Alireza
2015-06-01
Currently, drug discovery approaches commonly assume a monotonic dose-response relationship. However, the assumption of monotonicity is increasingly being challenged. Here we show that for two simple interacting linear signaling pathways that carry two different signals with different physiological responses, a non-monotonic input-output relation can arise with simple network topologies including coherent and incoherent feed-forward loops. We show that non-monotonicity of the response functions has severe implications for pharmacological treatment. Fundamental constraints are imposed on the effectiveness and toxicity of any drug independent of its chemical nature and selectivity due to the specific network structure.
Mikhaylov, V. E.; Khomenok, L. A.; Sherapov, V. V.
2016-08-01
The main problems in creation and operation of modern air inlet paths of gas turbine plants installed as part of combined-cycle plants in Russia are presented. It is noted that design features of air inlet filters shall be formed at the stage of the technical assignment not only considering the requirements of gas turbine plant manufacturer but also climatic conditions, local atmospheric air dustiness, and a number of other factors. The recommendations on completing of filtration system for air inlet filter of power gas turbine plants depending on the facility location are given, specific defects in design and experience in operation of imported air inlet paths are analyzed, and influence of cycle air preparation quality for gas turbine plant on value of operating expenses and cost of repair works is noted. Air treatment equipment of various manufacturers, influence of aerodynamic characteristics on operation of air inlet filters, features of filtration system operation, anti-icing system, weather canopies, and other elements of air inlet paths are considered. It is shown that nonuniformity of air flow velocity fields in clean air chamber has a negative effect on capacity and aerodynamic resistance of air inlet filter. Besides, the necessity in installation of a sufficient number of differential pressure transmitters allowing controlling state of each treatment stage not being limited to one measurement of total differential pressure in the filtration system is noted in the article. According to the results of the analysis trends and methods for modernization of available equipment for air inlet path, the importance of creation and implementation of new technologies for manufacturing of filtering elements on sites of Russia within the limits of import substitution are given, and measures on reliability improvement and energy efficiency for air inlet filter are considered.
Todd, E C; Szabo, R A; MacKenzie, J M; Martin, A; Rahn, K; Gyles, C; Gao, A; Alves, D; Yee, A J
1999-11-01
Verotoxigenic Escherichia coli (VTEC) strains were isolated from food and animal fecal samples by using PCR to screen for the presence of VTEC after broth enrichment and then filtering VTEC-positive cultures through hydrophobic-grid membrane filters (HGMFs) which were incubated on MacConkey agar. The filters were probed with a digoxigenin-labeled PCR product generated by amplification of a conserved verotoxin gene sequence. Replication of the growth on filters allowed probe-positive colonies to be picked. When ground beef samples were inoculated with VTEC strains, 100% of the strains were recovered, and the detection limit was 0.1 CFU per g. Similar results were obtained with seven types of artificially contaminated vegetables. A survey of 32 packages of vegetables and 23 samples of apple cider obtained at the retail level did not reveal the presence of VTEC. However, the intestinal fecal contents of a moose, 1 of 35 wild mammals and birds examined, contained E. coli O157:H7. The DNA hybridization-HGMF method was also used in a prevalence survey of 327 raw and 744 ready-to-eat products; VTEC strains were recovered from 4.9% of the raw products and 0.7% of the ready-to-eat products. No serotype O157:H7 strains were detected. This method is particularly suited for surveys in which low numbers of VTEC-positive samples are expected and isolates are required.
Todd, E. C. D.; Szabo, R. A.; MacKenzie, J. M.; Martin, A.; Rahn, K.; Gyles, C.; Gao, A.; Alves, D.; Yee, A. J.
1999-01-01
Verotoxigenic Escherichia coli (VTEC) strains were isolated from food and animal fecal samples by using PCR to screen for the presence of VTEC after broth enrichment and then filtering VTEC-positive cultures through hydrophobic-grid membrane filters (HGMFs) which were incubated on MacConkey agar. The filters were probed with a digoxigenin-labeled PCR product generated by amplification of a conserved verotoxin gene sequence. Replication of the growth on filters allowed probe-positive colonies to be picked. When ground beef samples were inoculated with VTEC strains, 100% of the strains were recovered, and the detection limit was 0.1 CFU per g. Similar results were obtained with seven types of artificially contaminated vegetables. A survey of 32 packages of vegetables and 23 samples of apple cider obtained at the retail level did not reveal the presence of VTEC. However, the intestinal fecal contents of a moose, 1 of 35 wild mammals and birds examined, contained E. coli O157:H7. The DNA hybridization-HGMF method was also used in a prevalence survey of 327 raw and 744 ready-to-eat products; VTEC strains were recovered from 4.9% of the raw products and 0.7% of the ready-to-eat products. No serotype O157:H7 strains were detected. This method is particularly suited for surveys in which low numbers of VTEC-positive samples are expected and isolates are required. PMID:10543785
Directory of Open Access Journals (Sweden)
K. Malathi
2014-09-01
Full Text Available A digital imaging technique is utilized in almost all the fields. Based on image processing concept image particle shape can be analyzed in detail. Nowadays, in eye clinics, imaging of the eye fundus with modern technology is in high demand because of its worth and expected lifetime. Eye fundus imaging is considered a non-invasive and painless route to screen and monitor the micro vascular distinction of diabetes and diabetic retinopathy. In general, Optic Disc (OD signifies the creation of the optic nerve. It is the point where the axons of retinal ganglion cells gain nearer. The Optic Disc is an access point of major blood vessels which provides the retina. In this study a method is introduced to automatically detect the position of the OD in digital retinal fundus images. The OD detection algorithm is based on the identical expected directional pattern of the retinal blood vessels. In this study two types of filters are proposed, one is Gaussian based bilateral filter, to reduce/eliminate the noise of the fundus images and another is a Haar filter to detect the diabetic retinopathy in the fundus images. The most excellent method to segment the images is thresholding based connected component pixels. The results have been taken from many diabetic retinopathy images. In this study for implementation efficient image filtering was used and named as OpenCV 2.4.9.0 and cvblobslib to accomplish successful result. In future development, the fovea detection will be applied.
A Two-Step Double Filter Method to Extract Open Water Surfaces from Landsat ETM+ Imagery
Wang, Haijing; Kinzelbach, Wolfgang
2010-05-01
In arid and semi-arid areas, lakes and temporal ponds play a significant role in agriculture and livelihood of local communities as well as in ecology. Monitoring the changes of these open water bodies allows to draw conclusions on water use as well as climatic impacts and can assist in the formulation of a sustainable resource management strategy. The simultaneous monitoring of larger numbers of water bodies with respect to their stage and area is feasible with the aid of remote sensing. Here the monitoring of lake surface areas is discussed. Landsat TM and ETM+ images provide a medium resolution of 30m, and offer an easily available data source to monitor the long term changes of water surfaces in arid and semi-arid regions. In the past great effort was put into developing simple indices to extract water surfaces from satellite images. However, there is a common problem in achieving accurate results with these indices: How to select a threshold value for water pixels without introducing excessive subjective judgment. The threshold value would also have to vary with location, land features and seasons, allowing for inherent uncertainty. A new method was developed using Landsat ETM+ imaginary (30 meter resolution) to extract open water surfaces. This method uses the Normalized Difference of Vegetation Index (NDVI) as the basis for an objective way of selecting threshold values of Modified Normalized Difference of Water Index (MNDWI) and Stress Degree Days (SDD), which were used as a combined filter to extract open water surfaces. We choose two study areas to verify the method. One study area is in Northeast China, where bigger lakes, smaller muddy ponds and wetlands are interspersed with agricultural land and salt crusts. The other one is Kafue Flats in Zambia, where seasonal floods of the Zambezi River create seasonal wetlands in addition to the more permanent water ponds and river channels. For both sites digital globe images of 0.5 meter resolution are available
Dealing with non-unique and non-monotonic response in particle sizing instruments
Rosenberg, Phil
2017-04-01
A number of instruments used as de-facto standards for measuring particle size distributions are actually incapable of uniquely determining the size of an individual particle. This is due to non-unique or non-monotonic response functions. Optical particle counters have non monotonic response due to oscillations in the Mie response curves, especially for large aerosol and small cloud droplets. Scanning mobility particle sizers respond identically to two particles where the ratio of particle size to particle charge is approximately the same. Images of two differently sized cloud or precipitation particles taken by an optical array probe can have similar dimensions or shadowed area depending upon where they are in the imaging plane. A number of methods exist to deal with these issues, including assuming that positive and negative errors cancel, smoothing response curves, integrating regions in measurement space before conversion to size space and matrix inversion. Matrix inversion (also called kernel inversion) has the advantage that it determines the size distribution which best matches the observations, given specific information about the instrument (a matrix which specifies the probability that a particle of a given size will be measured in a given instrument size bin). In this way it maximises use of the information in the measurements. However this technique can be confused by poor counting statistics which can cause erroneous results and negative concentrations. Also an effective method for propagating uncertainties is yet to be published or routinely implemented. Her we present a new alternative which overcomes these issues. We use Bayesian methods to determine the probability that a given size distribution is correct given a set of instrument data and then we use Markov Chain Monte Carlo methods to sample this many dimensional probability distribution function to determine the expectation and (co)variances - hence providing a best guess and an uncertainty for
Directory of Open Access Journals (Sweden)
Xintao Xia
2013-05-01
Full Text Available In this study, we propose the improved relative-entropy of the ideal circle function to the measured information of the radius error of the workpiece surface to make an eccentricity filtering in roundness measurement. Along with a correct assessment for the parameters of the eccentricity filtering, the extracted information from the measured information is obtained by the minimization of the improved relative-entropy. The case studies show that the information optimization is characterized by decreasing the improved relative-entropy, the extracted information almost coincides with the real information, the improved relative-entropy has a strong immunity to the stochastic disturbance of the rough work piece-surface and the increase of the minimum of the improved relative-entropy counteracts the effect of the stochastic disturbance on the assessment for parameters in eccentricity filtering.
Train velocity estimation method based on an adaptive filter with fuzzy logic
Pichlík, Petr; Zděnek, Jiří
2017-03-01
The train velocity is difficult to determine when the velocity is measured only on the driven or braked locomotive wheelsets. In this case, the calculated train velocity is different from the actual train velocity due to slip velocity or skid velocity respectively. The train velocity is needed for a locomotive controller proper work. For this purpose, an adaptive filter that is tuned by a fuzzy logic is designed and described in the paper. The filter calculates the train longitudinal velocity based on locomotive wheelset velocity. The fuzzy logic is used for the tuning of the filter according to actual wheelset acceleration and wheelset jerk. The simulation results are based on real measured data on a freight train. The results show that the calculated velocity corresponds to the actual train velocity.
Improved detection of coliforms and Escherichia coli in foods by a membrane filter method.
Sharpe, A N; Peterkin, P I; Malik, N
1979-09-01
Analytical procedures based on filtration of homogenates through membrane filters, and particularly hydrophobic grid-membrane filters (HGMF), offer definite improvements in the enumeration of Escherichia coli and coliforms in foods. Whereas the counted specimen in pour plates may not usually be greater than 0.1 g, up to 1.0 g of ground beef, green beans, potato, cod, strawberries, or grapes could be filtered and counted on HGMF. Greatly improved limit of detection, reduced interference by noncoliforms, and complete removal of growth inhibitors such as polyphenols were demonstrated for HGMF, using violet red bile and mFC agars. In addition, counting on HGMF eliminated a false-positive reaction caused by sucrose in ice cream.
Ito, Yuji; Doki, Shinji; Okuma, Sigeru
1-bit signal processing based on delta-sigma modulation has been studied for hardware implementation of signal processng systems. In the 1-bit signal processing, finite word-length problems such as overflow and coefficent quantization error occur. To solve the problems, new design method with state space is proposed in this paper. Digital filters are designed to show the feasibility of the method. Firstly, L1/L2-sensitivity is shown to evaluate coefficient quantization error and L2 scaling constraints to prevent overflow. Secondly, state space equation is shown and L1/L2-sensitivity and L2-scaling constraints are extended to take filter structure and oversampling effects into account. Finally, the proposed method is shown to attain higher SNR than conventional ones.
Institute of Scientific and Technical Information of China (English)
ZENG Qing-hu; QIU Jing; LIU Guan-jun
2007-01-01
Noise is the biggest obstacle that makes the incipient fault diagnosis results of roller bearings uncorrected; a new method for diagnosing incipient fault of roller bearings based on the Wavelet Transform Correlation Filter and Hilbert Transform was proposed. First, the weak fault information features are picked up from the roller bearings fault vibration signals by use of a de-noising characteristic of the Wavelet Transform Correlation Filter as the preprocessing of the Hilbert Envelope Analysis. Then, in order to get fault features frequency, de-noised wavelet coefficients of high scales which represent high frequency signal were analyzed by Hilbert Envelope Spectrum Analysis. The simulation signals and diagnosing examples analysis results reveal that the proposed method is more effective than the method of direct wavelet coefficients-Hilbert Transform in de-noising and clarifying roller bearing incipient fault.
Natori, Youichi; Kawamoto, Kazuhiko; Takahashi, Hiroshi; Hirota, Kaoru
A traffic accident prediction method using a priori knowledge based on accident data is proposed for safe driving support. Implementation is achieved by an algorithm using particle filtering and fuzzy inference to estimate accident risk factors. With this method, the distance between the host vehicle and a vehicle ahead and their relative velocity and relative acceleration are obtained from the results of particle filtering of driving data and are used as attributes to build the relative driving state space. The attributes are evaluated as likelihoods and then consolidated as a risk level using fuzzy inference. Experimental validation was done using videos of general driving situations obtained with an on-vehicle CCD camera and one simulated accident situation created based on the video data. The results show that high risk levels were calculated with the proposed method in the early stages of the accident situations.
Vincze, Julianna; Valiskó, Mónika; Boda, Dezso
2010-10-21
We propose a simple model to explain the nonmonotonic concentration dependence of the mean activity coefficient of simple electrolytes without using any adjustable parameters. The primitive model of electrolytes is used to describe the interaction between ions computed by the adaptive grand canonical Monte Carlo method. For the dielectric constant of the electrolyte, we use experimental concentration dependent values. This is included through a solvation term in our treatment to describe the interaction between ions and water that changes as the dielectric constant changes with concentration. This term is computed by a Born-treatment fitted to experimental hydration energies. Our results for LiCl, NaCl, KCl, CsCl, NaBr, NaI, MgCl(2), CaCl(2), SrCl(2), and BaCl(2) demonstrate that the principal reason of the nonmonotonic behavior of the activity coefficient is a balance between the solvation and ion-ion correlation terms. This conclusion differs from previous studies that assumed that it is the balance of hard sphere repulsion and electrostatic attraction that produces the nonmonotonic behavior. Our results indicate that the earlier assumption that solvation can be taken into account by a larger, "solvated" ionic radius should be reconsidered. To explain second order effects (such as dependence on ionic size), we conclude that explicit water models are needed.
Oswald, J. E.; Siegel, P. H.
1994-01-01
The finite difference time domain (FDTD) method is applied to the analysis of microwave, millimeter-wave and submillimeter-wave filter circuits. In each case, the validity of this method is confirmed by comparison with measured data. In addition, the FDTD calculations are used to design a new ultra-thin coplanar-strip filter for feeding a THz planar-antenna mixer.
The Implementation of Hard-Disk Protection Method Based on Disk Filter Driver
Yangwu Liu; Xisan Wei
2013-01-01
In this paper, it analyzes the working mechanism for the hard disk protection based on the current disk filter driver. The core ideology of the mechanism is to redirect the I/O request packet to the disk operation and to restore data automatically after restart the system in the case of transparent operating system to its upper storey. Also, it specifically analyzes the safety trouble by new virus, like the emerging virus, which can penetrate through the filter driver and results the failure ...
Sampling and handling artifacts can bias filter-based measurements of particulate organic carbon (OC). Several measurement-based methods for OC artifact reduction and/or estimation are currently used in research-grade field studies. OC frequently is not artifact-corrected in larg...
Entis, P
1989-01-01
Twenty-four laboratories participated in a collaborative study to validate a hydrophobic grid membrane filter (HGMF) method incorporating the use of 4-methylumbelliferyl-beta-D-glucuronide (MUG) for enumeration of total coliform and Escherichia coli bacteria in foods by comparing its performance against the AOAC 3-tube MPN method (46.013-46.016). Raw milk, raw ground poultry, whole egg powder, cheese powder, and ground black pepper were included in the study. The total coliform methods did not differ significantly, except that the 3-tube method detected a significantly higher level of total coliforms than did the HGMF method in the ground black pepper. Conversely, the HGMF/MUG E. coli method detected significantly higher numbers of E. coli present in the egg powder, cheese powder, and ground black pepper samples, while not differing significantly from the 3-tube method for the raw milk and raw ground poultry samples. The overall confirmation rate of MUG-positive colonies isolated using the HGMF method was 99.5%. The hydrophobic grid membrane filter/MUG method has been adopted official first action as an additional method to AOAC official final action method 46.030-46.034.
Maria, Roberta Manzano; Moraes, Tiago Bueno; Magon, Claudio José; Venâncio, Tiago; Altei, Wanessa Fernanda; Andricopulo, Adriano Defini; Colnago, Luiz Alberto
2012-10-01
Proton nuclear magnetic resonance ((1)H NMR) spectroscopy for detection of biochemical changes in biological samples is a successful technique. However, the achieved NMR resolution is not sufficiently high when the analysis is performed with intact cells. To improve spectral resolution, high resolution magic angle spinning (HR-MAS) is used and the broad signals are separated by a T(2) filter based on the CPMG pulse sequence. Additionally, HR-MAS experiments with a T(2) filter are preceded by a water suppression procedure. The goal of this work is to demonstrate that the experimental procedures of water suppression and T(2) or diffusing filters are unnecessary steps when the filter diagonalization method (FDM) is used to process the time domain HR-MAS signals. Manipulation of the FDM results, represented as a tabular list of peak positions, widths, amplitudes and phases, allows the removal of water signals without the disturbing overlapping or nearby signals. Additionally, the FDM can also be used for phase correction and noise suppression, and to discriminate between sharp and broad lines. Results demonstrate the applicability of the FDM post-acquisition processing to obtain high quality HR-MAS spectra of heterogeneous biological materials.
Directory of Open Access Journals (Sweden)
Leandro Vargas-Meléndez
2016-08-01
Full Text Available This article presents a novel estimator based on sensor fusion, which combines the Neural Network (NN with a Kalman filter in order to estimate the vehicle roll angle. The NN estimates a “pseudo-roll angle” through variables that are easily measured from Inertial Measurement Unit (IMU sensors. An IMU is a device that is commonly used for vehicle motion detection, and its cost has decreased during recent years. The pseudo-roll angle is introduced in the Kalman filter in order to filter noise and minimize the variance of the norm and maximum errors’ estimation. The NN has been trained for J-turn maneuvers, double lane change maneuvers and lane change maneuvers at different speeds and road friction coefficients. The proposed method takes into account the vehicle non-linearities, thus yielding good roll angle estimation. Finally, the proposed estimator has been compared with one that uses the suspension deflections to obtain the pseudo-roll angle. Experimental results show the effectiveness of the proposed NN and Kalman filter-based estimator.
Vargas-Meléndez, Leandro; Boada, Beatriz L; Boada, María Jesús L; Gauchía, Antonio; Díaz, Vicente
2016-08-31
This article presents a novel estimator based on sensor fusion, which combines the Neural Network (NN) with a Kalman filter in order to estimate the vehicle roll angle. The NN estimates a "pseudo-roll angle" through variables that are easily measured from Inertial Measurement Unit (IMU) sensors. An IMU is a device that is commonly used for vehicle motion detection, and its cost has decreased during recent years. The pseudo-roll angle is introduced in the Kalman filter in order to filter noise and minimize the variance of the norm and maximum errors' estimation. The NN has been trained for J-turn maneuvers, double lane change maneuvers and lane change maneuvers at different speeds and road friction coefficients. The proposed method takes into account the vehicle non-linearities, thus yielding good roll angle estimation. Finally, the proposed estimator has been compared with one that uses the suspension deflections to obtain the pseudo-roll angle. Experimental results show the effectiveness of the proposed NN and Kalman filter-based estimator.
Implementing method of optimum front-end conditioner based on Butterworth filter
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
The front-end conditioner is an essential part of digital systems of nuclear spectrometer, which functions in two ways: (1) prevents saturation of the subsequent ADC; (2) limits the bandwidth of frequency to realize anti-aliasing. To realize the above-mentioned functions, an optimum front-end conditioner for a resistive feedback charge-sensitive preamplifier is designed. In the conditioner, the pole-zero compensation (P/Z compensation) technique was used to effectively filter signals from the preamplifier. The Butterworth filter was improved after the pole-zero position was optimally set up to shape the wave of output, which tallied with the whole system. The front-end conditioner can resolve the aberration of waveform of nuclear signals in a regular Butterworth filter. Compared with the traditional triple-pole filtering circuitry, the circuitry of this conditioner is more compact and flexible.Moreover, its output waveform is more symmetrical and the signal-to-noise ratio (SNR) is higher. The improvement in the resolution of spectrometer is also significant.
Photonic-Crystal Band-pass Resonant Filters Design Using the Two-dimensional FDTD Method
Directory of Open Access Journals (Sweden)
Hadjira Badaoui
2011-05-01
Full Text Available Recently, band-pass photonic crystal filters have attracted great attention due to their important applications in the fields of optical interconnection network and ultrahigh speed information processing. In this paper we propose the design of a new type of photonic crystal band-pass resonant filters realized in one-missing-row waveguide by decreasing proper defects along the waveguide with broadband acceptable bandwidth. Two types of photonic crystal band-pass filters are utilized and optimized using the Two-dimensional finite-difference time-domain (FDTD technique. The first one is based on the Fabry-Perot cavities and in the second one a cavity is introduced in the middle by omitting two neighboring air holes in waveguide. Numerical results show that a band [1.47 and#956;m-1.57 and#956;m] around 1.55um is transmitted with a maximum transmission of about 68% and as a result wide band-pass filters are designed.
Modeling of HVDC in Dynamic State Estimation Using Unscented Kalman Filter Method
DEFF Research Database (Denmark)
Khazraj, Hesam; Silva, Filipe Miguel Faria da; Bak, Claus Leth
2016-01-01
HVDC transmission is an integral part of various power system networks. This article presents an Unscented Kalman Filter dynamic state estimator algorithm that considers the presence of HVDC links. The AC - DC power flow analysis, which is implemented as power flow solver for Dynamic State...
A METHOD FOR RECORDING AND VIEWING STEREOSCOPIC IMAGES IN COLOUR USING MULTICHROME FILTERS
DEFF Research Database (Denmark)
2000-01-01
in a conventional stereogram recorded of the scene. The invention makes use of a colour-based encoding technique and viewing filters selected so that the human observer receives, in one eye, an image of nearly full colour information, in the other eye, an essentially monochrome image supplying the parallactic...
Yoon, Heesung; Park, Eungyu; Yoon, Pilsun; Lee, Eunhee; Kim, Gyoo-Bum
2016-04-01
A method to filter out the effect of river stage fluctuations on groundwater level was designed using an artificial neural network-based time series model of groundwater level prediction. The designed method was applied to daily groundwater level data near the Gangjeong-Koryeong Barrage in the Nakdong river, South Korea. First, one-step ahead direct prediction time series models were successfully developed for both cases of before and after the barrage construction using past measurement data of rainfall, river stage, and groundwater level as inputs. The correlation coefficient values between observed and predicted data were over 0.97. Based on the direct prediction models, recursive prediction models for the simulation of groundwater level fluctuations were designed. The effect of river stage fluctuation on groundwater level data was filtered out by setting a constant value for river stage inputs of the recursive time series models. The hybrid water table fluctuation method was employed to estimate the groundwater recharge using the filtered data. The calculated ratios of groundwater recharge to precipitation before and after the barrage construction were 11.0% and 4.3%, respectively. It is expected that the proposed method can be a useful tool for groundwater level prediction and recharge estimation in the riverside area.
Yao, Yu; Cheng, Kai; Zhou, Zhi-Jie; Zhang, Bang-Cheng; Dong, Chao; Zheng, Sen
2015-11-01
A tracked vehicle has been widely used in exploring unknown environments and military fields. In current methods for suiting soil conditions, soil parameters need to be given and the traction performance cannot always be satisfied on soft soil. To solve the problem, it is essential to estimate track-soil parameters in real-time. Therefore, a detailed mathematical model is proposed for the first time. Furthermore, a novel algorithm which is composed of Kalman filter (KF) and improved strong tracking filter (STF) is developed for online track-soil estimation and named as KF-ISTF. By this method, the KF is used to estimate slip parameters, and the ISTF is used to estimate motion states. Then the key soil parameters can be estimated by using a suitable soil model. The experimental results show that equipped with the estimation algorithm, the proposed model can be used to estimate the track-soil parameters, and make the traction performance satisfied with soil conditions.
Solvent pre-wetting as an effective start-up method for point-of-use filter
Umeda, Toru; Sugiyama, Shinichi; Nakamura, Takashi; Momota, Makoto; Sevegney, Michael; Tsuzuki, Shuichi; Numaguchi, Toru
2012-03-01
An effective filter start-up method has been required by device manufacturers, mainly in order to reduce waste volume of lithography process chemicals, which become more expensive as lithography technology advances. Remaining air was monitored during static-pressure-driven filter start-up. As a result, 3500 ml of the resist was needed to eliminate remaining air. For improvement, cyclohexanone pre-wetting was applied prior to the resist introduction. As a result, the resist volume needed for the solvent displacement was 1900 ml, approximately half the volume required for staticpressure- driven start-up. Other solvents were evaluated for the pre-wetting start-up method. Results, in descending order of performance were PGME (best) Hansen solubility parameter distance between each solvent and nylon 6,6 material.
Bifurcations of a predator-prey model with non-monotonic response function
Broer, H.W.; Naudot, Vincent; Roussarie, Robert; Saleh, Khairul
2005-01-01
A 2-dimensional predator-prey model with five parameters is investigated, adapted from the Volterra-Lotka system by a non-monotonic response function. A description of the various domains of structural stability and their bifurcations is given. The bifurcation structure is reduced to four organising
Nonmonotonous concentration behaviour of T sub c in Van-Hove scenario
Kozlov, A N
2002-01-01
Dependence of T sub c on doping in the Hubbard model with a low- repulsion in the range of carrier concentration, where the Cooper amplitude depends on the system vicinity to spin density wave transition, is considered. It is shown that in the Van Hove scenario in the range of optimal doping nonmonotonous dependence of T sub c on carrier concentration is observed
Directory of Open Access Journals (Sweden)
J. H. Lee
2012-04-01
Full Text Available Aerodynamic roughness height (Z_{om} is a key parameter required in land surface hydrological model, since errors in heat flux estimations are largely dependent on accurate optimization of this parameter. Despite its significance, it remains an uncertain parameter that is not easily determined. This is mostly because of non-linear relationship in Monin-Obukhov Similarity (MOS and unknown vertical characteristic of vegetation. Previous studies determined aerodynamic roughness using traditional wind profile method, remotely sensed vegetation index, minimization of cost function over MOS relationship or linear regression. However, these are complicated procedures that presume high accuracy for several other related parameters embedded in MOS equations. In order to simplify a procedure and reduce the number of parameters in need, this study suggests a new approach to extract aerodynamic roughness parameter via Ensemble Kalman Filter (EnKF that affords non-linearity and that requires only single or two heat flux measurement. So far, to our knowledge, no previous study has applied EnKF to aerodynamic roughness estimation, while a majority of data assimilation study has paid attention to land surface state variables such as soil moisture or land surface temperature. This approach was applied to grassland in semi-arid Tibetan area and maize on moderately wet condition in Italy. It was demonstrated that aerodynamic roughness parameter can inversely be tracked from data assimilated heat flux analysis. The aerodynamic roughness height estimated in this approach was consistent with eddy covariance result and literature value. Consequently, this newly estimated input adjusted the sensible heat overestimated and latent heat flux underestimated by the original Surface Energy Balance System (SEBS model, suggesting better heat flux estimation especially during the summer Monsoon period. The advantage of this approach over other methodologies is
CSIR Research Space (South Africa)
Pretorius, C
2010-11-01
Full Text Available determines how the dust is distributed on the filter (analysis area of XRD vs FTIR). Current research Acknowledgements The Mine Health and Safety Council (MHSC) of South Africa provided the funding for this research project (SIM 080601) References 1.... ?MDHS 101. Direct-on-filter analysis by infrared spectroscopy and X-ray diffraction?, February 2005, Health and Safety Laboratory: Methods for the Determination of Hazardous Substances. 2. Occupational Health and Safety Administration (OSHA), Quartz...
Lozano, R. L.; Bolívar, J. P.; San Miguel, E. G.; García-Tenorio, R.; Gázquez, M. J.
2011-12-01
In this work, an accurate method for the measurement of natural alpha-emitting radionuclides from aerosols collected in air filters is presented and discussed in detail. The knowledge of the levels of several natural alpha-emitting radionuclides (238U, 234U, 232Th, 230Th, 228Th, 226Ra and 210Po) in atmospheric aerosols is essential not only for a better understanding of the several atmospheric processes and changes, but also for a proper evaluation of the potential doses, which can inadvertently be received by the population via inhalation. The proposed method takes into account the presence of intrinsic amounts of these radionuclides in the matrices of the quartz filters used, as well as the possible variation in the humidity of the filters throughout the collection process. In both cases, the corrections necessary in order to redress these levels have been evaluated and parameterized. Furthermore, a detailed study has been performed into the optimisation of the volume of air to be sampled in order to increase the accuracy in the determination of the radionuclides. The method as a whole has been applied for the determination of the activity concentrations of U- and Th-isotopes in aerosols collected at two NORM (Naturally Occurring Radioactive Material) industries located in the southwest of Spain. Based on the levels found, a conservative estimation has been performed to yield the additional committed effective doses to which the workers are potentially susceptible due to inhalation of anthropogenic material present in the environment of these two NORM industries.
Tuchman, M; Auray-Blais, C; Ramnaraine, M L; Neglia, J; Krivit, W; Lemieux, B
1987-06-01
Urinary homovanillic (HVA) and vanillylmandelic (VMA) acids were analyzed on 200 random urine samples from patients with neuroblastoma and controls, after the samples had been dried onto absorbent filter paper. The acids were determined quantitatively by gas chromatography (GC) and qualitatively by thin layer chromatography (TLC). The results were analyzed for correlation between liquid urine samples and urine dried on filter paper and between TLC and GC methods. A high overall correlation for HVA and VMA (99%) was found between liquid and dried filter samples analyzed by GC. The correlations were more significant for samples with elevated levels of these acids than for those with normal levels. Normalization of the results to the urinary creatinine concentration (UCr) is indicated due to variations in urine concentration. Results from TLC analysis showed a false positive rate of 3.5% and a false negative rate of 0.5% compared to GC analysis. This work suggests that a combination of a sensitive TLC method with a rapid quantitative GC method would be suitable for mass neuroblastoma screening in infants.
Naive Bayesian for Email Filtering
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The paper presents a method of email filter based on Naive Bayesian theory that can effectively filter junk mail and illegal mail. Furthermore, the keys of implementation are discussed in detail. The filtering model is obtained from training set of email. The filtering can be done without the users specification of filtering rules.
Saito, Masatoshi
2009-08-01
Dual-energy computed tomography (DECT) has the potential for measuring electron density distribution in a human body to predict the range of particle beams for treatment planning in proton or heavy-ion radiotherapy. However, thus far, a practical dual-energy method that can be used to precisely determine electron density for treatment planning in particle radiotherapy has not been developed. In this article, another DECT technique involving a balanced filter method using a conventional x-ray tube is described. For the spectral optimization of DECT using balanced filters, the author calculates beam-hardening error and air kerma required to achieve a desired noise level in electron density and effective atomic number images of a cylindrical water phantom with 50 cm diameter. The calculation enables the selection of beam parameters such as tube voltage, balanced filter material, and its thickness. The optimized parameters were applied to cases with different phantom diameters ranging from 5 to 50 cm for the calculations. The author predicts that the optimal combination of tube voltages would be 80 and 140 kV with Tb/Hf and Bi/Mo filter pairs for the 50-cm-diameter water phantom. When a single phantom calibration at a diameter of 25 cm was employed to cover all phantom sizes, maximum absolute beam-hardening errors were 0.3% and 0.03% for electron density and effective atomic number, respectively, over a range of diameters of the water phantom. The beam-hardening errors were 1/10 or less as compared to those obtained by conventional DECT, although the dose was twice that of the conventional DECT case. From the viewpoint of beam hardening and the tube-loading efficiency, the present DECT using balanced filters would be significantly more effective in measuring the electron density than the conventional DECT. Nevertheless, further developments of low-exposure imaging technology should be necessary as well as x-ray tubes with higher outputs to apply DECT coupled with the
Kypraios, Ioannis; Young, Rupert C. D.; Birch, Philip M.; Chatwin, Christopher R.
2003-08-01
The various types of synthetic discriminant function (sdf) filter result in a weighted linear superposition of the training set images. Neural network training procedures result in a non-linear superposition of the training set images or, effectively, a feature extraction process, which leads to better interpolation properties than achievable with the sdf filter. However, generally, shift invariance is lost since a data dependant non-linear weighting function is incorporated in the input data window. As a compromise, we train a non-linear superposition filter via neural network methods with the constraint of a linear input to allow for shift invariance. The filter can then be used in a frequency domain based optical correlator. Simulation results are presented that demonstrate the improved training set interpolation achieved by the non-linear filter as compared to a linear superposition filter.
Pyramidal Edge Detection Method Based on AWFM Filtering and Fuzzy Linking Model
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
A novel multiresolution pyramidal edge detector, based on adaptive weighted fuzzy mean(AWFM)filtering and fuzzy linking model, is presented in this paper. The algorithm first constructs a pyramidal structure by repetitive AWFM filtering and subsampling of original image. Then it utilizes multiple heuristic linking criteria between the edge nodes of two adjacent levels and considers the linkage as a fuzzy model, which is trained offline. Through this fuzzy linking model, the boundaries detected at coarse resolution are propagated and refined to the bottom level from the coarse-to fine edge detection. The validation experiment results demonstrate that the proposed approach has superior performance compared with standard fixed resolution detector andprevious multiresolution approach, especially in impulse noise environment.
C2DF: High Rate DDOS filtering method in Cloud Computing
Directory of Open Access Journals (Sweden)
Pourya Shamsolmoali
2014-08-01
Full Text Available Distributed Denial of Service (DDOS attacks have become one of the main threats in cloud environment. A DDOS attack can make large scale of damages to resources and access of the resources to genuine cloud users. Old-established defending system cannot be easily applied in cloud computing due to their relatively low competence and wide storage. In this paper we offered a data mining and neural network technique, trained to detect and filter DDOS attacks. For the simulation experiments we used KDD Cup dataset and our lab datasets. Our proposed model requires small storage and ability of fast detection. The obtained results indicate that our model has the ability to detect and filter most type of TCP attacks. Detection accuracy was the metric used to evaluate the performance of our proposed model. From the simulation results, it is visible that our algorithms achieve high detection accuracy (97% with fewer false alarms.
Argumentation-Based Non-Monotonic Reasoning of Agents%基于论辩的Agent非单调推理
Institute of Scientific and Technical Information of China (English)
廖备水; 代建华
2012-01-01
现有的Agent信念修正、慎思、手段-目的推理等理论和方法大多基于经典一阶逻辑,对不完全的、不一致的知识,缺乏有效的处理机制.基于论辩的Agent非单调推理(包括认识推理和实践推理)理论和方法有望弥补这个不足.不过,作为一个新的研究方向,其基本概念、理论、方法及存在的关键性问题尚有待于澄清和梳理.文中首先介绍论辩的基本概念.在此基础上,分析基于论辩的Agent非单调推理的最新研究进展.最后,讨论存在的关键性问题并指出可能的研究方向.%Most of existing theories and methods for belief revision, deliberation, means-ends reasoning etc. are based on classical first order logic, and therefore effective mechanisms are absent in handling incomplete and inconsistent knowledge. Argumentation-based non-monotonic reasoning, including epistemic reasoning and practical reasoning, has become a promising theory to solve the above-mentioned problem. However, as an emerging research area, the basic notions, theories, methods, as well as the existing research problems, are still unclear. In this paper, after presenting the basic notions of argumentation, the recent development of argumentation-based non-monotonic reasoning of agents is analyzed. Finally, some challenging problems are discussed, and the possible future work is pointed out.
Analog filtering methods improve leading edge timing performance of multiplexed SiPMs
Bieniosek, M. F.; Cates, J. W.; Grant, A. M.; Levin, C. S.
2016-08-01
Multiplexing many SiPMs to a single readout channel is an attractive option to reduce the readout complexity of high performance time of flight (TOF) PET systems. However, the additional dark counts and shaping from each SiPM cause significant baseline fluctuations in the output waveform, degrading timing measurements using a leading edge threshold. This work proposes the use of a simple analog filtering network to reduce the baseline fluctuations in highly multiplexed SiPM readouts. With 16 SiPMs multiplexed, the FWHM coincident timing resolution for single 3~\\text{mm}× 3~\\text{mm}× 20 mm LYSO crystals was improved from 401 ± 4 ps without filtering to 248 ± 5 ps with filtering. With 4 SiPMs multiplexed, using an array of 3~\\text{mm}× 3~\\text{mm}× 20 mm LFS crystals the mean time resolution was improved from 436 ± 6 ps to 249 ± 2 ps. Position information was acquired with a novel binary positioning network. All experiments were performed at room temperature with no active temperature regulation. These results show a promising technique for the construction of high performance multiplexed TOF PET readout systems using analog leading edge timing pickoff.
Directory of Open Access Journals (Sweden)
Yuanqiang Ren
2017-05-01
Full Text Available Structural health monitoring (SHM of aircraft composite structure is helpful to increase reliability and reduce maintenance costs. Due to the great effectiveness in distinguishing particular guided wave modes and identifying the propagation direction, the spatial-wavenumber filter technique has emerged as an interesting SHM topic. In this paper, a new scanning spatial-wavenumber filter (SSWF based imaging method for multiple damages is proposed to conduct on-line monitoring of aircraft composite structures. Firstly, an on-line multi-damage SSWF is established, including the fundamental principle of SSWF for multiple damages based on a linear piezoelectric (PZT sensor array, and a corresponding wavenumber-time imaging mechanism by using the multi-damage scattering signal. Secondly, through combining the on-line multi-damage SSWF and a PZT 2D cross-shaped array, an image-mapping method is proposed to conduct wavenumber synthesis and convert the two wavenumber-time images obtained by the PZT 2D cross-shaped array to an angle-distance image, from which the multiple damages can be directly recognized and located. In the experimental validation, both simulated multi-damage and real multi-damage introduced by repeated impacts are performed on a composite plate structure. The maximum localization error is less than 2 cm, which shows good performance of the multi-damage imaging method. Compared with the existing spatial-wavenumber filter based damage evaluation methods, the proposed method requires no more than the multi-damage scattering signal and can be performed without depending on any wavenumber modeling or measuring. Besides, this method locates multiple damages by imaging instead of the geometric method, which helps to improve the signal-to-noise ratio. Thus, it can be easily applied to on-line multi-damage monitoring of aircraft composite structures.
Ren, Yuanqiang; Qiu, Lei; Yuan, Shenfang; Bao, Qiao
2017-05-11
Structural health monitoring (SHM) of aircraft composite structure is helpful to increase reliability and reduce maintenance costs. Due to the great effectiveness in distinguishing particular guided wave modes and identifying the propagation direction, the spatial-wavenumber filter technique has emerged as an interesting SHM topic. In this paper, a new scanning spatial-wavenumber filter (SSWF) based imaging method for multiple damages is proposed to conduct on-line monitoring of aircraft composite structures. Firstly, an on-line multi-damage SSWF is established, including the fundamental principle of SSWF for multiple damages based on a linear piezoelectric (PZT) sensor array, and a corresponding wavenumber-time imaging mechanism by using the multi-damage scattering signal. Secondly, through combining the on-line multi-damage SSWF and a PZT 2D cross-shaped array, an image-mapping method is proposed to conduct wavenumber synthesis and convert the two wavenumber-time images obtained by the PZT 2D cross-shaped array to an angle-distance image, from which the multiple damages can be directly recognized and located. In the experimental validation, both simulated multi-damage and real multi-damage introduced by repeated impacts are performed on a composite plate structure. The maximum localization error is less than 2 cm, which shows good performance of the multi-damage imaging method. Compared with the existing spatial-wavenumber filter based damage evaluation methods, the proposed method requires no more than the multi-damage scattering signal and can be performed without depending on any wavenumber modeling or measuring. Besides, this method locates multiple damages by imaging instead of the geometric method, which helps to improve the signal-to-noise ratio. Thus, it can be easily applied to on-line multi-damage monitoring of aircraft composite structures.
Entis, P
1990-01-01
A collaborative study was carried out in 30 laboratories to validate improvements to the official final action hydrophobic grid membrane filter (HGMF) screening method for Salmonella in foods, 985.42, by comparing the performance of the improved HGMF method against that of the AOAC/BAM conventional culture method. Six products were included in the collaborative study: milk chocolate, raw deboned poultry meat, black pepper, soy flour, egg yolk powder, and nonfat dry milk. The raw deboned poultry meat was naturally contaminated with Salmonella, and the remaining 5 products were each inoculated in advance with low levels of individual Salmonella serotypes. The AOAC/BAM method produced 11 false negative results and the improved HGMF method produced 18 false negative results. The improved HGMF Salmonella method has been approved interim official first action for all foods to replace the HGMF official final action method, 985.42.
Tankanag, Arina V; Chemeris, Nikolay K
2009-10-01
The paper describes an original method for analysis of the peripheral blood flow oscillations measured with the laser Doppler flowmetry (LDF) technique. The method is based on the continuous wavelet transform and adaptive wavelet theory and applies an adaptive wavelet filtering to the LDF data. The method developed allows one to examine the dynamics of amplitude oscillations in a wide frequency range (from 0.007 to 2 Hz) and to process both stationary and non-stationary short (6 min) signals. The capabilities of the method have been demonstrated by analyzing LDF signals registered in the state of rest and upon humeral occlusion. The paper shows the main advantage of the method proposed, which is the significant reduction of 'border effects', as compared to the traditional wavelet analysis. It was found that the low-frequency amplitudes obtained by adaptive wavelets are significantly higher than those obtained by non-adaptive ones. The method suggested would be useful for the analysis of low-frequency components of the short-living transitional processes under the conditions of functional tests. The method of adaptive wavelet filtering can be used to process stationary and non-stationary biomedical signals (cardiograms, encephalograms, myograms, etc), as well as signals studied in the other fields of science and engineering.
Gröger, S.; Burkhardt, T.; Dietzsch, M.
2011-08-01
For a specific manipulation of friction surfaces it is important to measure and calculate geometrical parameters to derive the tribological behavior. The new functional approach presented in this paper is the calculation of the characteristic lateral extension of the real contact surface as well as the representative contact radius by applying morphological filters to a 3D-set of data. All surface characteristics, including form, waviness, roughness as well as defined microstructures, are extracted holistically with a 3D Coordinate Measuring Instrument or a Form Measuring Instrument, but with the smallest available tip radius. The paper presents the benefit of this holistic extraction method and the application of morphological filtering for the description of the contact form (plateau or sphere), the real contact surface, number of contacts, the typical contact radius and the typical lateral extension of the micro contact plateaus.
OCT图像降噪混合滤波方法%Mixed filtering method for OCT image denoising
Institute of Scientific and Technical Information of China (English)
李佳; 王笑梅
2011-01-01
通过对光学相干层析(OCT)系统中的噪音源进行分析,提出一种混合滤波处理方法,对OCT图像进行降噪处理.利用小波变换的原理将含噪图像进行小波分解,得到高频和低频的子信号,保留低频近似图像信号,分别对水平、垂直和对角3个方向的高频信号采用均值滤波,并将之前保留的低频近似图像信号与滤波后的这3个方向上的信号合成得到去噪后的图像.实验结果表明,该算法在降低噪声的同时尽可能的保留了图像细节,取得了良好的降噪效果.%Through the analysis of noise sources of optical coherence tomography (OCT) system, a mixed filtering method for noise reduction on the OCT image is put forward.Firstly, the noisy image is to be decomposed to the high frequency and low fiequency subsignals in accordance with the principle of wavelet transformation, and then retains the low-frequency approximate image signal, using mean filter respectively to horizontal, vertical and diagonal high-frequency signals in three directions.Finally, the denoised image will be obtained by the integration of the filtered image signals from the low-frequency proximate signals and signals filtered from the three directions.Experimental results show that, in reducing the noise, the method retains image details and achieves a good noise reduction result.
Rios-Zertuche, Rodolfo
This dissertation presents a novel extremum seeking control method which combines a time-varying Kalman filter with a Newton Raphson algorithm. The Kalman filter is used to estimate the gradient and Hessian of a performance function. The resulting estimates are used in the Newton Raphson algorithm to guide the system to a local extremum of the performance function. Convergence of the method to a local extremum is proven when the system is subject to noisy measurements. This is accomplished by showing that the output of the algorithm is a supermartingale. It is shown that the system will converge to an area around the extremum with a radius defined, in part, by the error covariance of the Kalman filter estimates. The method is applied to two examples. The first utilizes a single independent parameter performance function. The second applies the method to the problem of formation flight for drag reduction. In the first example, two implementations of the method are examined. The first uses only gradient estimates. The second uses both gradient and Hessian estimates. Both implementations show good convergence in the presence of noisy measurements. The second example is of formation flight for drag reduction. The problem is described in some detail and includes an aerodynamic development of the drag-reduction phenomenon. The problem is explored with two simulations. The first uses coefficient of induced drag as its performance function and estimates the gradient and Hessian of the performance function. It shows good convergence of the method. The second simulation first uses pitch angle and then aileron deflection as its performance function. It estimates the gradient but not the Hessian of the performance function. It also shows good convergence.
Xu, Zhenqiang; Xu, Hong; Yao, Maosheng
2013-05-01
In this study, a "modified" mixed cellulose ester (MCE) filter culturing method (directly placing filter on agar plate for culturing without extraction) was investigated in enumerating airborne culturable bacterial and fungal aerosol concentration and diversity both in different environments. A Button Inhalable Sampler loaded with a MCE filter was operated at a flow rate of 5 L/min to collect indoor and outdoor air samples using different sampling times: 10, 20, and 30 min in three different time periods of the day. As a comparison, a BioStage impactor, regarded as the gold standard, was operated in parallel at a flow rate of 28.3 L/min for all tests. The air samples collected by the Button Inhalable Sampler were directly placed on agar plates for culturing, and those collected by the BioStage impactor were incubated directly at 26 °C. The colony forming units (CFUs) were manually counted and the culturable concentrations were calculated both for bacterial and fungal aerosols. The bacterial CFUs developed were further washed off and subjected to polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE) for diversity analysis. For fungal CFUs, microscopy method was applied to studying the culturable fungal diversity obtained using different methods. Experimental results showed that the performance of two investigated methods varied with sampling environments and microbial types (culturable bacterial and fungal aerosols). For bacterial aerosol sampling, both methods were shown to perform equally well, and in contrast the "modified" MCE filter method was demonstrated to enumerate more culturable fungal aerosols than the BioStage impactor. In general, the microbial species richness (number of gel bands) was observed to increase with increasing collection time. For both methods, the DGGE gel patterns were observed to vary with sampling time and environment despite of similar number of gel bands. In addition, an increase in sampling time from 20 to 30 min
Directory of Open Access Journals (Sweden)
Wanli Liu
2015-07-01
Full Text Available Differential interferometric synthetic aperture radar has been shown to be effective for monitoring subsidence in coal mining areas. Phase unwrapping can have a dramatic influence on the monitoring result. In this paper, a filtering-based phase unwrapping algorithm in combination with path-following is introduced to unwrap differential interferograms with high noise in mining areas. It can perform simultaneous noise filtering and phase unwrapping so that the pre-filtering steps can be omitted, thus usually retaining more details and improving the detectable deformation. For the method, the nonlinear measurement model of phase unwrapping is processed using a simplified Cubature Kalman filtering, which is an effective and efficient tool used in many nonlinear fields. Three case studies are designed to evaluate the performance of the method. In Case 1, two tests are designed to evaluate the performance of the method under different factors including the number of multi-looks and path-guiding indexes. The result demonstrates that the unwrapped results are sensitive to the number of multi-looks and that the Fisher Distance is the most suitable path-guiding index for our study. Two case studies are then designed to evaluate the feasibility of the proposed phase unwrapping method based on Cubature Kalman filtering. The results indicate that, compared with the popular Minimum Cost Flow method, the Cubature Kalman filtering-based phase unwrapping can achieve promising results without pre-filtering and is an appropriate method for coal mining areas with high noise.
Liu, Wanli; Bian, Zhengfu; Liu, Zhenguo; Zhang, Qiuzhao
2015-07-06
Differential interferometric synthetic aperture radar has been shown to be effective for monitoring subsidence in coal mining areas. Phase unwrapping can have a dramatic influence on the monitoring result. In this paper, a filtering-based phase unwrapping algorithm in combination with path-following is introduced to unwrap differential interferograms with high noise in mining areas. It can perform simultaneous noise filtering and phase unwrapping so that the pre-filtering steps can be omitted, thus usually retaining more details and improving the detectable deformation. For the method, the nonlinear measurement model of phase unwrapping is processed using a simplified Cubature Kalman filtering, which is an effective and efficient tool used in many nonlinear fields. Three case studies are designed to evaluate the performance of the method. In Case 1, two tests are designed to evaluate the performance of the method under different factors including the number of multi-looks and path-guiding indexes. The result demonstrates that the unwrapped results are sensitive to the number of multi-looks and that the Fisher Distance is the most suitable path-guiding index for our study. Two case studies are then designed to evaluate the feasibility of the proposed phase unwrapping method based on Cubature Kalman filtering. The results indicate that, compared with the popular Minimum Cost Flow method, the Cubature Kalman filtering-based phase unwrapping can achieve promising results without pre-filtering and is an appropriate method for coal mining areas with high noise.
A NEW DESIGN METHOD OF CDMA SPREADING CODES BASED ON MULTI-RATE UNITARY FILTER BANK
Institute of Scientific and Technical Information of China (English)
Bi Jianxin; Wang Yingmin; Yi Kechu
2001-01-01
It is well-known that the multi-valued CDMA spreading codes can be designed by means of a pair of mirror multi-rate filter banks based on some optimizing criterion. This paper indicates that there exists a theoretical bound in the performance of its circulating correlation property, which is given by an explicit expression. Based on this analysis, a criterion of maximizing entropy is proposed to design such codes. Computer simulation result suggests that the resulted codes outperform the conventional binary balanced Gold codes for an asynchronous CDMA system.
Cheng, Xuemin; Hao, Qun; Xie, Mengdi
2016-04-07
Video stabilization is an important technology for removing undesired motion in videos. This paper presents a comprehensive motion estimation method for electronic image stabilization techniques, integrating the speeded up robust features (SURF) algorithm, modified random sample consensus (RANSAC), and the Kalman filter, and also taking camera scaling and conventional camera translation and rotation into full consideration. Using SURF in sub-pixel space, feature points were located and then matched. The false matched points were removed by modified RANSAC. Global motion was estimated by using the feature points and modified cascading parameters, which reduced the accumulated errors in a series of frames and improved the peak signal to noise ratio (PSNR) by 8.2 dB. A specific Kalman filter model was established by considering the movement and scaling of scenes. Finally, video stabilization was achieved with filtered motion parameters using the modified adjacent frame compensation. The experimental results proved that the target images were stabilized even when the vibrating amplitudes of the video become increasingly large.
Institute of Scientific and Technical Information of China (English)
LI; Zicheng; SUN; Yukun
2006-01-01
Considering the detection principle that "when load current is periodic current, the integral in a cycle for absolute value of load current subtracting fundamental active current is the least", harmonic current real-time detection methods for power active filter are proposed based on direct computation, simple iterative algorithm and optimal iterative algorithm. According to the direct computation method, the amplitude of the fundamental active current can be accurately calculated when load current is placed in stable state. The simple iterative algorithm and the optimal iterative algorithm provide an idea about judging the state of load current. On the basis of the direct computation method, the simple iterative algorithm, the optimal iterative algorithm and precise definition of the basic concepts such as the true amplitude of the fundamental active current when load current is placed in varying state, etc., the double linear construction idea is proposed in which the amplitude of the fundamental active current at the moment of the sample is accurately calculated by using the first linear construction and the condition which disposes the next sample is created by using the second linear construction. On the basis of the double linear construction idea, a harmonic current real-time detection method for power active filter is proposed based on the double linear construction algorithm. This method has the characteristics of small computing quantity, fine real-time performance, being capable of accurately calculating the amplitude of the fundamental active current and so on.
McDaniels, A E; Bordner, R H; Menkedick, J R; Weber, C I
1987-05-01
The hydrophobic-grid membrane filter (HGMF) has been proposed as an alternate method to the standard membrane filter (MF) procedure for the detection and enumeration of coliforms from water. Eight samples of nonchlorinated wastewater effluents were analyzed by the HGMF, standard MF, and tube fermentation most-probable-number methods for fecal coliforms, and eight samples each of polluted surface and dosed drinking waters were analyzed by the same methods for total coliforms. The drinking waters were dosed with coliforms and other heterotrophs concentrated from nonchlorinated domestic wastewater and treated with chlorine to reduce the numbers of organisms and simulate stress caused by chlorination. Statistical analyses determined that recoveries of fecal coliforms were significantly higher by the filtration methods for the nonchlorinated domestic wastewaters but not for the other waters. The results also indicated that recoveries of fecal and total coliforms did not differ significantly when either MFs or HGMFs were used. Total coliform results obtained with HGMFs having greater than 100 positive grid cells were significantly more precise than estimates obtained by the standard MF method only for polluted surface waters.
Goutham, Venkatesh H; Kamalesh, Mumbrekar D; Guruprasad, Parashiva K; Vadhiraja, Manjunath B; Satyamoorthy, Kapaettu; Rao Bola Satish, Sadashiva
2011-07-15
Neutral filter elution assay is one of the methods used for detection of DNA double strand breaks (DSBs). However, it is laborious, expensive, and hazardous (radiolabeled precursors for DSB detection and scintillation counter for quantification), making it a less preferred method for DSB detection. In the present study, an attempt was made to improve the existing neutral filter elution assay by making use of fluorescent dye (PicoGreen) and microfiltration assembly for eluting the fragmented DNA, thereby reducing the cost and time required for the assay. We studied the effect of dye dilution, pH conditions, and cell number as a part of method standardization. X-ray dose-response and repair kinetics in lymphocytes as well as cell lines were studied for validating the sensitivity of the assay. A linear dose-response relationship for DSBs was observed at a cell number of 4×10(5)cells, a dye dilution of 500-fold, and at pH 10. Repair kinetics revealed a time-dependent repair of DSBs up to 360 min of posttreatment, indicating its usefulness in DSB repair studies. In conclusion, the present modified method is more efficient (in terms of cell number), cost effective, less time-consuming, and less hazardous compared to the existing method. Copyright © 2011 Elsevier Inc. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Juxiu Tong; Bill X. Hu; Hai Huang; Luanjin Guo; Jinzhong Yang
2014-03-01
With growing importance of water resources in the world, remediations of anthropogenic contaminations due to reactive solute transport become even more important. A good understanding of reactive rate parameters such as kinetic parameters is the key to accurately predicting reactive solute transport processes and designing corresponding remediation schemes. For modeling reactive solute transport, it is very difficult to estimate chemical reaction rate parameters due to complex processes of chemical reactions and limited available data. To find a method to get the reactive rate parameters for the reactive urea hydrolysis transport modeling and obtain more accurate prediction for the chemical concentrations, we developed a data assimilation method based on an ensemble Kalman filter (EnKF) method to calibrate reactive rate parameters for modeling urea hydrolysis transport in a synthetic one-dimensional column at laboratory scale and to update modeling prediction. We applied a constrained EnKF method to pose constraints to the updated reactive rate parameters and the predicted solute concentrations based on their physical meanings after the data assimilation calibration. From the study results we concluded that we could efficiently improve the chemical reactive rate parameters with the data assimilation method via the EnKF, and at the same time we could improve solute concentration prediction. The more data we assimilated, the more accurate the reactive rate parameters and concentration prediction. The filter divergence problem was also solved in this study.
Xiong, Binyu; Zhao, Jiyun; Wei, Zhongbao; Skyllas-Kazacos, Maria
2014-09-01
State of charge (SOC) estimation is a key issue for battery management since an accurate estimation method can ensure safe operation and prevent the over-charge/discharge of a battery. Traditionally, open circuit voltage (OCV) method is utilized to estimate the stack SOC and one open flow cell is needed in each battery stack [1,2]. In this paper, an alternative method, extended Kalman filter (EKF) method, is proposed for SOC estimation for VRBs. By measuring the stack terminal voltages and applied currents, SOC can be predicted with a state estimator instead of an additional open circuit flow cell. To implement EKF estimator, an electrical model is required for battery analysis. A thermal-dependent electrical circuit model is proposed to describe the charge/discharge characteristics of the VRB. Two scenarios are tested for the robustness of the EKF. For the lab testing scenarios, the filtered stack voltage tracks the experimental data despite the model errors. For the online operation, the simulated temperature rise is observed and the maximum SOC error is within 5.5%. It is concluded that EKF method is capable of accurately predicting SOC using stack terminal voltages and applied currents in the absence of an open flow cell for OCV measurement.
Grziwa, Sascha; Korth, Judith; Paetzold, Martin; KEST
2016-10-01
The Rheinisches Institut für Umweltforschung (RIU-PF) has developed the software package EXOTRANS for the detection of transits of exoplanets in stellar light curves. This software package was in use during the CoRoT space mission (2006-2013). EXOTRANS was improved by different wavelet-based filter methods during the following years to separate stellar variation, orbital disturbances and instrumental effects from stellar light curves taken by space telescopes (Kepler, K2, TESS and PLATO). The VARLET filter separates faint transit signals from stellar variations without using a-priori information about the target star. VARLET considers variations by frequency, amplitude and shape simultaneously. VARLET is also able to extract most instrumental jumps and glitches. The PHALET filter separates periodic features independent of their shape and is used with the intention to separate diluting stellar binaries. It is also applied for the multi transit search. Stellar light curves of the K2 mission are constructed from the processing of target pixel files which corrects disturbances caused by the reduced pointing precision of the Kepler telescope after the failure of two gyroscopes. The combination of target pixel file processing with both filter techniques and the proven detection pipeline EXOTRANS lowers the detection limit, reduces false alarms and simplifies the detection of faint transits in light curves of the K2 mission. Using EXOTRANS many new candidates were detected in K2 light curves by using EXOTRANS which were successfully confirmed by ground-based follow-up observation of the KEST collaboration. New candidates and confirmed planets are presented.
Kamboures, Michael A.; Rieger, Paul L.; Zhang, Sherry; Sardar, Satya B.; Chang, M.-C. Oliver; Huang, Shiou-Mei; Dzhema, Inna; Fuentes, Mark; Benjamin, Michael T.; Hebert, Annette; Ayala, Alberto
2015-12-01
As part of the California Air Resources Board's effort to confirm the ability of the vehicular particulate matter (PM) reference method (RM) to measure PM emissions at sub-one milligram per mile (mg/mi), and to explore alternative methods, we evaluated a combination method (CM) that utilizes both gravimetric and real-time particle quantification. PM, collected on a single composite filter is apportioned to the three Federal Test Procedure (FTP) cycle phases using real-time equivalent black carbon (EBC) measurements, reducing the need to carry out separate gravimetric filter measurements for each of the test phases. Four light-duty gasoline vehicles, emitting PM at or below one mg/mi, were dynamometer tested repeatedly on the FTP cycle. PM was quantified by the RM and by two variants of the CM. One variant used photoacoustic spectroscopy to measure EBC (CM-MSS), and the other used an Aethalometer (CM-AE51). The CM was evaluated on repeatability, bias, and correlation with the RM. For the tested vehicles, the observed repeatability of the CM was superior to the RM regardless of the mode of EBC measurement or the test vehicle considered (σCM-MSS = 0.08 mg/mi, σCM-AE51 = 0.07 mg/mi, σRM ≈ 0.11 mg/mi). However, the CM was negatively biased by -0.08 mg/mi, versus the RM, in one of the test vehicles. We attribute the bias in this vehicle's data to organic carbon emissions that were not equivalently collected on the composite filter of the CM. When all data were combined, the correlation between the methods was good (R = 0.90 for CM-MSS vs. RM and R = 0.91 for CM-AE51 vs. RM).
Shimizu, Hidenori; Benno, Yoshimi
2015-11-01
A large number of commensal bacteria inhabit the intestinal tract, and interbacterial communication among gut microbiota is thought to occur. In order to analyze symbiotic relationships between probiotic strains and the gut microbiota, a ring with a membrane filter fitted to the bottom was used for in vitro investigations. Test strains comprising probiotic nitto strains (Lactobacillus acidophilus NT and Bifidobacterium longum NT) and type strains (L. acidophilus JCM1132(T) and B. longum JCM1217(T) ) were obtained from diluted fecal samples using the membrane filter to simulate interbacterial communication. Bifidobacterium spp., Streptococcus pasteurianus, Collinsella aerofaciens, and Clostridium spp. were the most abundant gut bacteria detected before coculture with the test strains. Results of the coculture experiments indicated that the test strains significantly promote the growth of Ruminococcus gnavus, Ruminococcus torques, and Veillonella spp. and inhibit the growth of Sutterella wadsworthensis. Differences in the relative abundances of gut bacterial strains were furthermore observed after coculture of the fecal samples with each test strain. Bifidobacterium spp., which was detected as the dominant strain in the fecal samples, was found to be unaffected by coculture with the test strains. In the present study, interbacterial communication using bacterial metabolites between the test strains and the gut microbiota was demonstrated by the coculture technique. The detailed mechanisms and effects of the complex interbacterial communications that occur among the gut microbiota are, however, still unclear. Further investigation of these relationships by coculture of several fecal samples with probiotic strains is urgently required.
Directory of Open Access Journals (Sweden)
Yanjian Peng
2016-04-01
Full Text Available Unlike the traditional method for power quality improvement and low-voltage ride through (LVRT capability enhancement of wind farms, this paper proposes a new wind power integrated system by means of an inductive filtering method, especially if it contains a grid-connected transformer, a static synchronous compensator (STATCOM and fully-tuned (FT branches. First, the main circuit topology of the new wind power integrated system is presented. Then, the mathematical model is established to reveal the mechanism of harmonic suppression and the reactive compensation of the proposed wind power integrated system, and then the realization conditions of the inductive filtering method is obtained. Further, the control strategy of STATCOM is introduced. Based on the measured data for a real wind farm, the simulation studies are carried out to illustrate the performance of the proposed new wind power integrated system. The results indicate that the new system can not only enhance the LVRT capability of wind farms, but also prevent harmonic components flowing into the primary (grid winding of the grid-connected transformer. Moreover, since the new method can compensate for reactive power in a wind farm, the power factor at the grid side can be improved effectively.
Needles, A; Couture, O; Foster, F S
2009-09-01
This study introduces a new method for differentiating targeted microbubbles in the presence of flowing microbubbles and tissue using micro-ultrasound. The method relies on subharmonic (SH) imaging for segmenting microbubble signals from tissue signals, and low-pass interframe filtering for segmenting bound targeted microbubbles from flowing microbubbles. The method is evaluated with 30 frames per second SH B-mode imaging in vitro, using a wall-less vessel flow phantom. The SH B-mode cineloops were postprocessed using an interframe moving average filter to segment the regions of bound microbubbles on the inner surface of the vessel phantom. The bound bubbles were then disrupted with sufficiently high ultrasound pressures, so that the dynamic process of targeted microbubble binding under flowing conditions could be observed. These preliminary results show that the proposed method is a feasible solution to the challenge of differentiating targeted microbubbles in the presence of tissue and freely flowing microbubbles at high frequencies, which in turn should improve the specificity of targeted microbubble detection.
Zhou, Zhenggan; Ma, Baoquan; Jiang, Jingtao; Yu, Guang; Liu, Kui; Zhang, Dongmei; Liu, Weiping
2014-10-01
Air-coupled ultrasonic testing (ACUT) technique has been viewed as a viable solution in defect detection of advanced composites used in aerospace and aviation industries. However, the giant mismatch of acoustic impedance in air-solid interface makes the transmission efficiency of ultrasound low, and leads to poor signal-to-noise (SNR) ratio of received signal. The utilisation of signal-processing techniques in non-destructive testing is highly appreciated. This paper presents a wavelet filtering and phase-coded pulse compression hybrid method to improve the SNR and output power of received signal. The wavelet transform is utilised to filter insignificant components from noisy ultrasonic signal, and pulse compression process is used to improve the power of correlated signal based on cross-correction algorithm. For the purpose of reasonable parameter selection, different families of wavelets (Daubechies, Symlet and Coiflet) and decomposition level in discrete wavelet transform are analysed, different Barker codes (5-13 bits) are also analysed to acquire higher main-to-side lobe ratio. The performance of the hybrid method was verified in a honeycomb composite sample. Experimental results demonstrated that the proposed method is very efficient in improving the SNR and signal strength. The applicability of the proposed method seems to be a very promising tool to evaluate the integrity of high ultrasound attenuation composite materials using the ACUT.
A strategy to model nonmonotonic dose-response curve and estimate IC50.
Zhang, Hui; Holden-Wiltse, Jeanne; Wang, Jiong; Liang, Hua
2013-01-01
The half-maximal inhibitory concentration IC[Formula: see text] is an important pharmacodynamic index of drug effectiveness. To estimate this value, the dose response relationship needs to be established, which is generally achieved by fitting monotonic sigmoidal models. However, recent studies on Human Immunodeficiency Virus (HIV) mutants developing resistance to antiviral drugs show that the dose response curve may not be monotonic. Traditional models can fail for nonmonotonic data and ignore observations that may be of biologic significance. Therefore, we propose a nonparametric model to describe the dose response relationship and fit the curve using local polynomial regression. The nonparametric approach is shown to be promising especially for estimating the IC[Formula: see text] of some HIV inhibitory drugs, in which there is a dose-dependent stimulation of response for mutant strains. This model strategy may be applicable to general pharmacologic, toxicologic, or other biomedical data that exhibits a nonmonotonic dose response relationship for which traditional parametric models fail.
A new non-monotone fitness scaling for genetic algorithm
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The properties of selection operators in the genetic algorithm (GA) are studied in detail. It is indicated that the selection of operations is significant for both improving the general fitness of a population and leading to the schema deceptiveness. The stochastic searching characteristics of GA are compared with those of heuristic methods. The influence of selection operators on the GA' s exploration and exploitation is discussed, and the performance of selection operators is evaluated with the premature convergence of the GA taken as an example based on One-Max function. In order to overcome the schema deceptiveness of the GA, a new type of fitness scaling, non monotone scaling, is advanced to enhance the evolutionary ability of a population. The effectiveness of the new scaling method is tested by a trap function and a needle-in-haystack (NiH) function.
Energy Technology Data Exchange (ETDEWEB)
FEHL,DAVID LEE; BIGGS,F.; CHANDLER,GORDON A.; STYGAR,WILLIAM A.
2000-01-17
The generalized method of Backus and Gilbert (BG) is described and applied to the inverse problem of obtaining spectra from a 5-channel, filtered array of x-ray detectors (XRD's). This diagnostic is routinely fielded on the Z facility at Sandia National Laboratories to study soft x-ray photons ({le}2300 eV), emitted by high density Z-pinch plasmas. The BG method defines spectral resolution limits on the system of response functions that are in good agreement with the unfold method currently in use. The resolution so defined is independent of the source spectrum. For noise-free, simulated data the BG approximating function is also in reasonable agreement with the source spectrum (150 eV black-body) and the unfold. This function may be used as an initial trial function for iterative methods or a regularization model.
Zhang, Dengfeng; Nakaya, Naoshi; Koui, Yuuji; Yoshida, Hitoaki
Recently, the appearance frequency of computer virus variants has increased. Updates to virus information using the normal pattern matching method are increasingly unable to keep up with the speed at which viruses occur, since it takes time to extract the characteristic patterns for each virus. Therefore, a rapid, automatic virus detection algorithm using static code analysis is necessary. However, recent computer viruses are almost always compressed and obfuscated. It is difficult to determine the characteristics of the binary code from the obfuscated computer viruses. Therefore, this paper proposes a method that unpacks compressed computer viruses automatically independent of the compression format. The proposed method unpacks the common compression formats accurately 80% of the time, while unknown compression formats can also be unpacked. The proposed method is effective against unknown viruses by combining it with the existing known virus detection system like Paul Graham's Bayesian Virus Filter etc.
A Strategy to Model Nonmonotonic Dose-Response Curve and Estimate IC50
Hui Zhang; Jeanne Holden-Wiltse; Jiong Wang; Hua Liang
2013-01-01
The half-maximal inhibitory concentration IC[Formula: see text] is an important pharmacodynamic index of drug effectiveness. To estimate this value, the dose response relationship needs to be established, which is generally achieved by fitting monotonic sigmoidal models. However, recent studies on Human Immunodeficiency Virus (HIV) mutants developing resistance to antiviral drugs show that the dose response curve may not be monotonic. Traditional models can fail for nonmonotonic data and igno...
Kohei Arai
2013-01-01
Recovering method of missing data based on the proposed modified Kalman filter for the case that the time series of mean data is know is proposed. There are some cases of which although a portion of data is missing, mean value of the time series of data is known. For instance, although coarse resolution of imagery data are acquired every day, fine resolution of imagery data are missing sometimes. In other words, coarse resolution of imaging sensor has wide swath width while fine resolution of...
Energy Technology Data Exchange (ETDEWEB)
Cirrone, G.A.P., E-mail: cirrone@lns.infn.it [Laboratori Nazionali del Sud - National Instiute for Nuclear Physics INFN (INFN-LNS), Via S.Sofia 64, 95100 Catania (Italy); Bucciolini, M. [Department of ' Fisiopatologia Clinica' , University of Florence, V.le Morgagni 85, I-50134 Florence (Italy); Bruzzi, M. [Energetic Department, University of Florence, Via S. Marta 3, I-50139 Florence (Italy); Candiano, G. [Laboratorio di Tecnologie Oncologiche HSR, Giglio Contrada, Pietrapollastra-Pisciotto, 90015 Cefalu, Palermo (Italy); Civinini, C. [National Institute for Nuclear Physics INFN, Section of Florence, Via G. Sansone 1, Sesto Fiorentino, I-50019 Florence (Italy); Cuttone, G. [Laboratori Nazionali del Sud - National Instiute for Nuclear Physics INFN (INFN-LNS), Via S.Sofia 64, 95100 Catania (Italy); Guarino, P. [Nuclear Engineering Department, University of Palermo, Via... Palermo (Italy); Laboratori Nazionali del Sud - National Instiute for Nuclear Physics INFN (INFN-LNS), Via S.Sofia 64, 95100 Catania (Italy); Lo Presti, D. [Physics Department, University of Catania, Via S. Sofia 64, I-95123, Catania (Italy); Mazzaglia, S.E. [Laboratori Nazionali del Sud - National Instiute for Nuclear Physics INFN (INFN-LNS), Via S.Sofia 64, 95100 Catania (Italy); Pallotta, S. [Department of ' Fisiopatologia Clinica' , University of Florence, V.le Morgagni 85, I-50134 Florence (Italy); Randazzo, N. [National Institute for Nuclear Physics INFN, Section of Catania, Via S.Sofia 64, 95123 Catania (Italy); Sipala, V. [National Institute for Nuclear Physics INFN, Section of Catania, Via S.Sofia 64, 95123 Catania (Italy); Physics Department, University of Catania, Via S. Sofia 64, I-95123, Catania (Italy); Stancampiano, C. [National Institute for Nuclear Physics INFN, Section of Catania, Via S.Sofia 64, 95123 Catania (Italy); and others
2011-12-01
In this paper the use of the Filtered Back Projection (FBP) Algorithm, in order to reconstruct tomographic images using the high energy (200-250 MeV) proton beams, is investigated. The algorithm has been studied in detail with a Monte Carlo approach and image quality has been analysed and compared with the total absorbed dose. A proton Computed Tomography (pCT) apparatus, developed by our group, has been fully simulated to exploit the power of the Geant4 Monte Carlo toolkit. From the simulation of the apparatus, a set of tomographic images of a test phantom has been reconstructed using the FBP at different absorbed dose values. The images have been evaluated in terms of homogeneity, noise, contrast, spatial and density resolution.
Non-monotonic size dependence of diffusion and levitation effect: a mode-coupling theory analysis.
Nandi, Manoj Kumar; Banerjee, Atreyee; Bhattacharyya, Sarika Maitra
2013-03-28
We present a study of diffusion of small tagged particles in a solvent, using mode coupling theory (MCT) analysis and computer simulations. The study is carried out for various interaction potentials. For the first time, using MCT, it is shown that only for strongly attractive interaction potential with allowing interpenetration between the solute-solvent pair the diffusion exhibits a non-monotonic solute size dependence which has earlier been reported in simulation studies [P. K. Ghorai and S. Yashonath, J. Phys. Chem. B 109, 5824-5835 (2005)]. For weak attractive and repulsive potential the solute size dependence of diffusion shows monotonic behaviour. It is also found that for systems where the interaction potential does not allow solute-solvent interpenetration, the solute cannot explore the neck of the solvent cage. Thus these systems even with strong attractive interaction will never show any non-monotonic size dependence of diffusion. This non-monotonic size dependence of diffusion has earlier been connected to levitation effect [S. Yashonath and P. Santikary, J. Phys. Chem. 98, 6368 (1994)]. We also show that although levitation is a dynamic phenomena, the effect of levitation can be obtained in the static radial distribution function.
Bianco, Vittorio; Memmolo, Pasquale; Paturzo, Melania; Finizio, Andrea; Ferraro, Pietro
2017-06-01
In digital holography (DH), the coherent nature of the employed light sources severely degrades the holographic reconstructions due to a mixture of speckle and incoherent additive noise. These can affect both the visual quality in holographic imaging and display, and the accuracy of quantitative phase-contrast reconstructions. Typically, the noise problem is tackled by reducing the illumination coherence, thus the most intuitive way involves the recording of multiple uncorrelated holograms to be incoherently combined. This framework is known as Multi-Look DH (MLDH). However, single shot recordings are highly desirable in DH, and numerical methods are required to go beyond the improvement bound of ML techniques. Among the existing image processing methods, the 3D Block Matching filtering (BM3D) has shown the best performance. Here we present the MLDH-BM3D, a method specifically suitable to filter DH images that combines the two aforementioned strategies to overcome their respective limitations. We demonstrate the effectiveness of this framework in three different experimental situations, i.e. reconstructions of single wavelength holograms and color holograms in the visible region and the challenging case of the Infrared Radiation Digital Holography (IRDH) reconstructions, where a very severe noise degradation occurs.
Kang, Yun
2011-01-01
Combined with all density-dependent factors, the per capita growth rate of a species may be non-monotonic. One important consequence is that species may suffer from weak Allee effects or strong Allee effects. In this paper, we study the permanence of a discrete-time two-species-interaction model with non-monotonic per capita growth rates for the first time. By using the average Lyapunov functions and extending the ecological concept of the relative nonlinearity, we find a simple sufficient condition for guaranteeing the permanence of systems that can model complicated two-species interactions. The extended relative nonlinearity allows us to fully characterize the effects of nonlinearities in the per capita growth functions with non-monotonicity. These results are illustrated with specific two species competition and predator-prey models of generic forms with non-monotone per capita growth rates.
A clock steering method: using a third-order type 3 DPLL equivalent to a Kalman filter with a delay
Wu, Yiwei; Gong, Hang; Zhu, Xiangwei; Ou, Gang
2015-12-01
In this paper we propose a new clock steering method, which uses a third-order type 3 digital phase locked loop (DPLL) which is equivalent to a Kalman filter with a delay. A general overview of the theoretical framework is described in detail including the transfer functions, the structure and control values, the specifications, and the approach to choosing a parameter. Simulations show that the performance of the time and frequency steering errors and the frequency stability are quite desirable. Comparing with traditional clock steering methods, it is easier to work with just one parameter. The DPLL method satisfies the requirements of generating a local representation of universal time coordinated and the system time of a global navigation satellite system.
Filter function synthesis by Gegenbauer generating function
Directory of Open Access Journals (Sweden)
Pavlović Vlastimir D.
2006-01-01
Full Text Available Low-pass all-pole transfer functions with non-monotonic amplitude characteristic in the pass-band and at least (n -1 flatness conditions for ω = 0 are considered in this paper. A new class of filters in explicit form with one free parameter is obtained by applying generating functions of Gegenbauer polynomials. This class of filters has good selectivity and good shape of amplitude characteristics in the pass-band. The amplitude characteristics of these transfer functions have gain in the upper part of pass-band with respect to the gain for ω = 0. This way we have greater margin of attenuation in the upper part of the pass-band. This means a greater tolerance of elements or for elements with given tolerances, greater ambient temperature changes. The appropriate choice of the free parameter enables us to generate filter functions obtained with Chebyshev polynomials of the first and second kind and Legendre polynomials.
Sánchez-Úbeda, Juan Pedro; Calvache, María Luisa; Duque, Carlos; López-Chicano, Manuel
2016-11-01
A new methodology has been developed to obtain tidal-filtered time series of groundwater levels in coastal aquifers. Two methods used for oceanography processing and forecasting of sea level data were adapted for this purpose and compared: HA (Harmonic Analysis) and CWT (Continuous Wavelet Transform). The filtering process is generally comprised of two main steps: the detection and fitting of the major tide constituents through the decomposition of the original signal and the subsequent extraction of the complete tidal oscillations. The abilities of the optional HA and CWT methods to decompose and extract the tidal oscillations were assessed by applying them to the data from two piezometers at different depths close to the shoreline of a Mediterranean coastal aquifer (Motril-Salobreña, SE Spain). These methods were applied to three time series of different lengths (one month, one year, and 3.7 years of hourly data) to determine the range of detected frequencies. The different lengths of time series were also used to determine the fit accuracies of the tidal constituents for both the sea level and groundwater heads measurements. The detected tidal constituents were better resolved with increasing depth in the aquifer. The application of these methods yielded a detailed resolution of the tidal components, which enabled the extraction of the major tidal constituents of the sea level measurements from the groundwater heads (e.g., semi-diurnal, diurnal, fortnightly, monthly, semi-annual and annual). In the two wells studied, the CWT method was shown to be a more effective method than HA for extracting the tidal constituents of highest and lowest frequencies from groundwater head measurements.
Chen, Sheng; Yao, Liping; Chen, Bao
2016-11-01
The enhancement of lung nodules in chest radiographs (CXRs) plays an important role in the manual as well as computer-aided detection (CADe) lung cancer. In this paper, we proposed a parameterized logarithmic image processing (PLIP) method combined with the Laplacian of a Gaussian (LoG) filter to enhance lung nodules in CXRs. We first applied several LoG filters with varying parameters to an original CXR to enhance the nodule-like structures as well as the edges in the image. We then applied the PLIP model, which can enhance lung nodule images with high contrast and was beneficial in extracting effective features for nodule detection in the CADe scheme. Our method combined the advantages of both the PLIP algorithm and the LoG algorithm, which can enhance lung nodules in chest radiographs with high contrast. To test our nodule enhancement method, we tested a CADe scheme, with a relatively high performance in nodule detection, using a publically available database containing 140 nodules in 140 CXRs enhanced through our nodule enhancement method. The CADe scheme attained a sensitivity of 81 and 70 % with an average of 5.0 frame rate (FP) and 2.0 FP, respectively, in a leave-one-out cross-validation test. By contrast, the CADe scheme based on the original image recorded a sensitivity of 77 and 63 % at 5.0 FP and 2.0 FP, respectively. We introduced the measurement of enhancement by entropy evaluation to objectively assess our method. Experimental results show that the proposed method obtains an effective enhancement of lung nodules in CXRs for both radiologists and CADe schemes.
A Kalman Filter-Based Method to Generate Continuous Time Series of Medium-Resolution NDVI Images
Directory of Open Access Journals (Sweden)
Fernando Sedano
2014-12-01
Full Text Available A data assimilation method to produce complete temporal sequences of synthetic medium-resolution images is presented. The method implements a Kalman filter recursive algorithm that integrates medium and moderate resolution imagery. To demonstrate the approach, time series of 30-m spatial resolution NDVI images at 16-day time steps were generated using Landsat NDVI images and MODIS NDVI products at four sites with different ecosystems and land cover-land use dynamics. The results show that the time series of synthetic NDVI images captured seasonal land surface dynamics and maintained the spatial structure of the landscape at higher spatial resolution. The time series of synthetic medium-resolution NDVI images were validated within a Monte Carlo simulation framework. Normalized residuals decreased as the number of available observations increased, ranging from 0.2 to below 0.1. Residuals were also significantly lower for time series of synthetic NDVI images generated at combined recursion (smoothing than individually at forward and backward recursions (filtering. Conversely, the uncertainties of the synthetic images also decreased when the number of available observations increased and combined recursions were implemented.
集成滤波器优化设计新方法%A New Method for Optimization Design of Integrated Filter
Institute of Scientific and Technical Information of China (English)
张瑜; 陈丹丹; 赵俊杰; 张磊昂
2012-01-01
In case to high sensitivity and wild fluctuaion problems which appeared in the design procedure of integrated filter, the study takes LC ladcler-lype filter as design prototype and optimizes the transfer function by applying the design margin which is generated by rounding the filter order to the nearest integer. Ry optimizing the the analytical formula for the low-pass filler design, it could receive the best analytical formulas of filter design. By utilizing Bruton transformation, it could transfer analog IX ladder-type filter into low-sensitivity integrated active filter. Simulation results .show that integrated filter which obtained by optimized design method not only has the advantage of low sensitivity as LC ladder-type filter, but also could improve the bandpass fluctuating range of filter without any increase in filter order number.%针对集成滤波器设计中灵敏度高,波动大的问题,以LC梯形滤波器为设计原型,利用滤波器设计阶数上取整后带来的设计余量优化传递函数.通过对低通滤波器设计解析公式的优化,得到了滤波器设计的最佳解析公式.借助Bruton变换,可使模拟LC梯形滤波器转化成低灵敏度集成有源滤波器.仿真实验表明,利用该优化设计方法得到的集成滤波器,不仅具有LC梯形滤波器元件变化灵敏度低的优点,又在不增加滤波器阶数的情况下,改善了滤波器通带波动范围.
New approach to safeguards accounting. [Kalman filter method for detecting continual small losses
Energy Technology Data Exchange (ETDEWEB)
Pike, D.H.; Morrison, G.W.
1977-03-01
In recent years there has been widespread concern over the problem of nuclear safeguards. Due to the proliferation of nuclear reactors throughout the world, the concern about the loss or diversion of nuclear materials at various points in the fuel cycle has greatly increased. To minimize the possibility of material loss, the nuclear industry relies on physical protection systems and materials accountability procedures at licensed facilities. Present techniques of material accountability rely on double-entry accounting systems. For various reasons, only noisy observations of on-hand inventory are available. Hence one is forced to use statistical techniques in an attempt to detect the existence of missing material. Current practice is to use control charts as the basis for detecting significant material losses. Control charts may aid in detecting large material losses but are insensitive to small quantities of material loss, even if these small losses occur repeatedly over a long period of time. The purpose of this research is to show the feasibility of using linear state estimation theory in nuclear material accountability. The Kalman Filter is used as the state estimation technique. The state vector which consists of on-hand inventory and material losses is estimated recursively.
An Optimal Orthogonal Decomposition Method for Kalman Filter-Based Turbofan Engine Thrust Estimation
Litt, Jonathan S.
2007-01-01
A new linear point design technique is presented for the determination of tuning parameters that enable the optimal estimation of unmeasured engine outputs, such as thrust. The engine's performance is affected by its level of degradation, generally described in terms of unmeasurable health parameters related to each major engine component. Accurate thrust reconstruction depends on knowledge of these health parameters, but there are usually too few sensors to be able to estimate their values. In this new technique, a set of tuning parameters is determined that accounts for degradation by representing the overall effect of the larger set of health parameters as closely as possible in a least squares sense. The technique takes advantage of the properties of the singular value decomposition of a matrix to generate a tuning parameter vector of low enough dimension that it can be estimated by a Kalman filter. A concise design procedure to generate a tuning vector that specifically takes into account the variables of interest is presented. An example demonstrates the tuning parameters ability to facilitate matching of both measured and unmeasured engine outputs, as well as state variables. Additional properties of the formulation are shown to lend themselves well to diagnostics.
Development of a digital method for neutron/gamma-ray discrimination based on matched filtering
Korolczuk, S.; Linczuk, M.; Romaniuk, R.; Zychor, I.
2016-09-01
Neutron/gamma-ray discrimination is crucial for measurements with detectors sensitive to both neutron and gamma-ray radiation. Different techniques to discriminate between neutrons and gamma-rays based on pulse shape analysis are widely used in many applications, e.g., homeland security, radiation dosimetry, environmental monitoring, fusion experiments, nuclear spectroscopy. A common requirement is to improve a radiation detection level with a high detection reliability. Modern electronic components, such as high speed analog to digital converters and powerful programmable digital circuits for signal processing, allow us to develop a fully digital measurement system. With this solution it is possible to optimize digital signal processing algorithms without changing any electronic components in an acquisition signal path. We report on results obtained with a digital acquisition system DNG@NCBJ designed at the National Centre for Nuclear Research. A 2'' × 2'' EJ309 liquid scintillator was used to register mixed neutron and gamma-ray radiation from PuBe sources. A dedicated algorithm for pulse shape discrimination, based on real-time filtering, was developed and implemented in hardware.
Grossman, M.W.
1993-02-16
The present invention is directed to a method of eliminating the cold spot zones presently used on Hg[sup 196] isotope separation lamps and filters by the use of a mercury amalgams, preferably mercury - indium amalgams. The use of an amalgam affords optimization of the mercury density in the lamp and filter of a mercury enrichment reactor, particularly multilamp enrichment reactors. Moreover, the use of an amalgam in such lamps and/or filters affords the ability to control the spectral line width of radiation emitted from lamps, a requirement for mercury enrichment.
Grossman, Mark W.
1993-01-01
The present invention is directed to a method of eliminating the cold spot zones presently used on Hg.sup.196 isotope separation lamps and filters by the use of a mercury amalgams, preferably mercury - indium amalgams. The use of an amalgam affords optimization of the mercury density in the lamp and filter of a mercury enrichment reactor, particularly multilamp enrichment reactors. Moreover, the use of an amalgam in such lamps and/or filters affords the ability to control the spectral line width of radiation emitted from lamps, a requirement for mercury enrichment.
Directory of Open Access Journals (Sweden)
M. Ramar
2014-09-01
Full Text Available Essential oils from 12 medicinal plants were evaluated by three different bioassay methods (Vaporizer, Filter paper and Aerosol for Knock-down and adulticidal efficacy on the filarial vector mosquito, Culex quinquefasciatus. Based on screening results the effective plants were selected for investigating Knock-down and adulticidal potential against adult female of the laboratory-reared mosquito species, Cx. quinquefasciatus. In vaporizer bioassay method four different doses (1.25, 2.5, 5 and 10% were used. Four different doses (0.625, 1.25, 2.5 and 10% were used both filter paper (cm2 and aerosol (cm3 bioassay methods. Five essential oils (calamus, camphor, citronella, clove and eucalyptus were identified as potential treatments in vaporizer bioassay. The result showed that the knock down time decreased with increased concentration in clove oil treatment; the Knock-down time (KT 50 = 46.1 ± 0.1, 38.5 ± 0.1, 30.7 ± 0.2, and 20.1 ± 0.1 minutes was recorded at 1.25, 2.5, 5 and 10% /cm3 respectively. In filter paper method nine essential oils were identified as potential treatments. After 1 hr exposure period clove oil recorded the lowest median Knock-down time (KT50 which was calculated as 9.15 ± 0.1min/cm2. Followed by citronella (KT50 =11.4 ± 0.1 min and eucalyptus (KT50 =11.4 ±0.1min oils since they recorded lower median Knock-down time. All the twelve essential oils were identified as potential treatments in aerosol activity. The lethal time decreased when the concentration increased. At 5 % concentration the median lethal time (LT50 for clove oil was calculated as (LT50=3.80 ± 0.1minutes. The Cinnamon oil was effective which recorded (LT50 = 1.99 mins as median lethal time. Camphor (LT50 =19.6± 0.1 min oil were found to be less toxic by aerosol method. These results suggest that clove oil and cinnamon oil have the potential to be used as a eco-friendly approach for the control of the major important filaria vector Cx. quinquefasciatus
Directory of Open Access Journals (Sweden)
Ningyun Zhang
2014-06-01
Full Text Available The Proportional Resonant (PR current controller provides gains at a certain frequency (resonant frequency and eliminates steady state errors. Therefore, the PR controller can be successfully applied to single grid-connected PV inverter current control. On the contrary, a PI controller has steady-state errors and limited disturbance rejection capability. Compared with the L- and LC filters, the LCL filter has excellent harmonic suppression capability, but the inherent resonant peak of the LCL filter may introduce instability in the whole system. Therefore, damping must be introduced to improve the control of the system. Considering the controller and the LCL filter active damping as a whole system makes the controller design method more complex. In fact, their frequency responses may affect each other. The traditional trial-and-error procedure is too time-consuming and the design process is inefficient. This paper provides a detailed analysis of the frequency response influence between the PR controller and the LCL filter regarded as a whole system. In addition, the paper presents a systematic method for designing controller parameters and the capacitor current feedback coefficient factor of LCL filter active-damping. The new method relies on meeting the stable margins of the system. Moreover, the paper also clarifies the impact of the grid on the inverter output current. Numerical simulation and a 3 kW laboratory setup assessed the feasibility and effectiveness of the proposed method.
Joint DOA and Fundamental Frequency Estimation Methods based on 2-D Filtering
DEFF Research Database (Denmark)
Jensen, Jesper Rindom; Christensen, Mads Græsbøll; Jensen, Søren Holdt
2010-01-01
It is well-known that ﬁltering methods can be used for processing of signals in both time and space. This comprises, for example, fundamental frequency estimation and direction-of-arrival (DOA) estimation. In this paper, we propose two novel 2-D ﬁltering methods for joint estimation...... of the fundamental frequency and the DOA of spatio-temporarily sampled periodic signals. The ﬁrst and simplest method is based on the 2-D periodogram, whereas the second method is a generalization of the 2-D Capon method. In the experimental part, both qualitative and quantitative measurements show that the proposed...... methods are well-suited for solving the joint estimation problem. Furthermore, it is shown that the methods are able to resolve signals separated sufﬁciently in only one dimension. In the case of closely spaced sources, however, the 2-D Capon-based method shows the best performance....
Fundamentals of Stochastic Filtering
Crisan, Dan
2008-01-01
The objective of stochastic filtering is to determine the best estimate for the state of a stochastic dynamical system from partial observations. The solution of this problem in the linear case is the well known Kalman-Bucy filter which has found widespread practical application. The purpose of this book is to provide a rigorous mathematical treatment of the non-linear stochastic filtering problem using modern methods. Particular emphasis is placed on the theoretical analysis of numerical methods for the solution of the filtering problem via particle methods. The book should provide sufficient
Azad, Mohammad-Reza; Koneshloo, Mohammad; Kamakar Rouhani, Abolghasem; Aghajani, Hamid
2016-04-01
To interpret geophysical anomaly maps, it is necessary to filter out regional and sometimes noise components. Each measured value in a gravity survey consists of different components. Upward continuation (UC) is one of the most widely used filters. The shortcoming of this filter is not to consider the spatial structure of the data, and also the fact that the trial and error approach and expert's judgment are needed to adjust it. This study aims to compare the factorial kriging analysis (FKA) and UC filters for separation of local and regional anomalies in the gravity data of a hydrocarbon field in the southeast sedimentary basins of the East Vietnam Sea. As shown in this paper, FKA method permits to filter out all of the identified structures, while the UC filter does not possess this capability. Therefore, beside general and classic filtering methods, the FKA method can be used as a strong method in filtering spatial structures and anomaly component.
Energy Technology Data Exchange (ETDEWEB)
Page, Ralph H.; Doty, Patrick F.
2017-08-01
The various technologies presented herein relate to a tiled filter array that can be used in connection with performance of spatial sampling of optical signals. The filter array comprises filter tiles, wherein a first plurality of filter tiles are formed from a first material, the first material being configured such that only photons having wavelengths in a first wavelength band pass therethrough. A second plurality of filter tiles is formed from a second material, the second material being configured such that only photons having wavelengths in a second wavelength band pass therethrough. The first plurality of filter tiles and the second plurality of filter tiles can be interspersed to form the filter array comprising an alternating arrangement of first filter tiles and second filter tiles.
Mousavi Anzehaee, Mohammad; Adib, Ahmad; Heydarzadeh, Kobra
2015-10-01
The manner of microtremor data collection and filtering operation and also the method used for processing have a considerable effect on the accuracy of estimation of dynamic soil parameters. In this paper, running variance method was used to improve the automatic detection of data sections infected by local perturbations. In this method, the microtremor data running variance is computed using a sliding window. Then the obtained signal is used to remove the ranges of data affected by perturbations from the original data. Additionally, to determinate the fundamental frequency of a site, this study has proposed a statistical characteristics-based method. Actually, statistical characteristics, such as the probability density graph and the average and the standard deviation of all the frequencies corresponding to the maximum peaks in the H/ V spectra of all data windows, are used to differentiate the real peaks from the false peaks resulting from perturbations. The methods have been applied to the data recorded for the City of Meybod in central Iran. Experimental results show that the applied methods are able to successfully reduce the effects of extensive local perturbations on microtremor data and eventually to estimate the fundamental frequency more accurately compared to other common methods.
Determination of Ar Concentration Evolution Within DIII-D Core Plasma by X-ray Ross Filter Method
Bogatu, I. N.; Edgell, D. H.; Brooks, N. H.; Snider, R. T.; West, W. P.; Wade, M. R.
2001-10-01
Injection of the non-recycling noble gas Ar into the DIII-D divertor is a promising technique for reducing the heat load on the plates; it also seems to improve thermal transport in an advanced operating mode. During such experiments core plasma contamination by migrating Ar can be investigated by measuring the evolution of the Ar concentration profile using the Ross filter method implemented on the fan shaped X-ray poloidal diagnostics on DIII-D. A Ross filter with energy pass band centered on the ArXVII K_α line at 3.14 keV, discriminating Ar K_α line against background radiation, was used on DIII-D. A high sensitivity to the injected quantity of Ar and good discrimination against Ne was observed. We present reconstruction of Ar concentration profiles from the chord-integrated measurements using the measured Te and ne profiles. Using the transport code MIST, the impurity diffusion coefficients can be determined by matching the time evolution of the Ar concentration evolution.
Directory of Open Access Journals (Sweden)
Pratap R. Patnaik
2008-04-01
Full Text Available Large-scale fed-batch fermentations are often subject to noise carried by the feed streams. This noise corrupts the process data and may destabilize the fermentation. So it is important to retrieve clear signals from noisy data. This is done by noise filters. The performances of some commonly used filters have been studied for poly-β-hydroxybutyrate production by Ralstonia eutropha. In simulated experiments, Gaussian noise was added to the flow rates of the carbon and nitrogen substrates. The filters were compared by means of the Lyapunov exponents of the outputs and their closeness to the noise-free performance. Negative exponents indicate a stable fermentation. An auto-associative neural filter performed the best, followed by a combination of a cusum filter and an extended Kalman filter. Butterworth filters were inferior and inadequate.
Adaptive filtering of electroencephalogram signals using the empirical-modes method
Grubov, V. V.; Runnova, A. E.; Koronovskii, A. A.; Hramov, A. E.
2017-07-01
A new method for the removal of physiological artifacts in the experimental signals of human electroencephalograms (EEGs) has been developed. The method is based on decomposition of the signal in terms of empirical modes. The algorithm involves EEG signal decomposition in terms of empirical modes, searching for modes with artifacts, removing these modes, and restoration of the EEG signal. The method was tested on experimental data and showed high efficiency in the removal of various physiological artifacts in EEGs.
Improved Sensitive Image Filtering Method%一种改进的敏感图像过滤方法
Institute of Scientific and Technical Information of China (English)
陆蓓; 陈法叶; 姚金良
2011-01-01
Aiming at the shortage that existing sensitive image filtering method has higher error rate, this paper presents a sensitive image filtering method by combining skin color detection with human detection by Histogram of Gradient(HOG). Extracting features of human bodies by HOG feature, using a detection model trained by Support Vector Machine(SVM) to find out the human body, and then using the skin color detection algorithm to tell whether the image is sensitive. Experimental results show that this method can detect the sensitive images under complex background effectively. The accurate rate can achieve 90.2%, the recall rate can achieve 86.3%, and the error rate can achieve 3.5%.%针对现有敏感图像过滤方法误检率较高的问题,提出一种结合肤色检测和方向梯度直方图(HOG)人体检测的敏感图像过滤方法.采用HOG特征提取人体目标的特征集,运用支持向量机训练人体检测模型,检验图像中是否存在人体,并结合肤色检测算法判别该图像是否为敏感图像.实验结果表明,该方法能有效检测复杂背景条件下的敏感图像,其精确度为90.2％、查全率为86.3％、误检率为3.5％.
Yuan, Shenfang; Chen, Jian; Yang, Weibo; Qiu, Lei
2017-08-01
Fatigue crack growth prognosis is important for prolonging service time, improving safety, and reducing maintenance cost in many safety-critical systems, such as in aircraft, wind turbines, bridges, and nuclear plants. Combining fatigue crack growth models with the particle filter (PF) method has proved promising to deal with the uncertainties during fatigue crack growth and reach a more accurate prognosis. However, research on prognosis methods integrating on-line crack monitoring with the PF method is still lacking, as well as experimental verifications. Besides, the PF methods adopted so far are almost all sequential importance resampling-based PFs, which usually encounter sample impoverishment problems, and hence performs poorly. To solve these problems, in this paper, the piezoelectric transducers (PZTs)-based active Lamb wave method is adopted for on-line crack monitoring. The deterministic resampling PF (DRPF) is proposed to be used in fatigue crack growth prognosis, which can overcome the sample impoverishment problem. The proposed method is verified through fatigue tests of attachment lugs, which are a kind of important joint component in aerospace systems.
Verweij, M.D.; Huijssen, J.
2009-01-01
The full-wave computation of transient acoustic fields with sizes in the order of 100x100x100 wavelengths by 100 periods requires a numerical method that is extremely efficient in terms of storage and computation. Iterative integral equation methods offer a good performance on these points, provided
Krishnaveni, M; Subashini, P
2009-01-01
A new fangled method for ship wake detection in synthetic aperture radar (SAR) images is explored here. Most of the detection procedure applies the Radon transform as its properties outfit more than any other transformation for the detection purpose. But still it holds problems when the transform is applied to an image with a high level of noise. Here this paper articulates the combination between the radon transformation and the shrinkage methods which increase the mode of wake detection process. The latter shrinkage method with RT maximize the signal to noise ratio hence it leads to most optimal detection of lines in the SAR images. The originality mainly works on the denoising segment of the proposed algorithm. Experimental work outs are carried over both in simulated and real SAR images. The detection process is more adequate with the proposed method and improves better than the conventional methods.
A Method to Small Stripline Interdigital Electric Filter Design%一种小型带状线交指滤波器的设计方法
Institute of Scientific and Technical Information of China (English)
缪建红; 徐琰; 汪霆雷
2012-01-01
The principle analysis of a small interdigital filter is presented. The stripline in- terdigital filter without side tuning screw has the advantages of small scale and low-loss. A new method of calculating the length of the rod is introduced. ANSOFT HFSS is used to simulate the filter. The performance of the filter is proved by simulation and practical tests.%介绍了一种小型带状线交指滤波器的研制过程,选用了薄型谐振杆并取消侧面调谐螺钉的方案实现小型低耗,提出了计算谐振杆端电容来确定杆长的设计方法,利用仿真软件进行了验证和分析,仿真和实测结果基本一致。
Energy Technology Data Exchange (ETDEWEB)
Beare, Richard; Brown, Michael J. I.; Pimbblet, Kevin, E-mail: richard@beares.net [Monash Centre for Astrophysics, Monash University, Clayton, Victoria 3800 (Australia)
2014-12-20
We describe an accurate new method for determining absolute magnitudes, and hence also K-corrections, that is simpler than most previous methods, being based on a quadratic function of just one suitably chosen observed color. The method relies on the extensive and accurate new set of 129 empirical galaxy template spectral energy distributions from Brown et al. A key advantage of our method is that we can reliably estimate random errors in computed absolute magnitudes due to galaxy diversity, photometric error and redshift error. We derive K-corrections for the five Sloan Digital Sky Survey filters and provide parameter tables for use by the astronomical community. Using the New York Value-Added Galaxy Catalog, we compare our K-corrections with those from kcorrect. Our K-corrections produce absolute magnitudes that are generally in good agreement with kcorrect. Absolute griz magnitudes differ by less than 0.02 mag and those in the u band by ∼0.04 mag. The evolution of rest-frame colors as a function of redshift is better behaved using our method, with relatively few galaxies being assigned anomalously red colors and a tight red sequence being observed across the whole 0.0 < z < 0.5 redshift range.
Banerjee, Amartya S; Hu, Wei; Yang, Chao; Pask, John E
2016-01-01
The Discontinuous Galerkin (DG) electronic structure method employs an adaptive local basis set to solve the equations of density functional theory in a discontinuous Galerkin framework. The methodology is implemented in the Discontinuous Galerkin Density Functional Theory (DGDFT) code for large-scale parallel electronic structure calculations. In DGDFT, the basis is generated on-the-fly to capture the local material physics, and can systematically attain chemical accuracy with only a few tens of degrees of freedom per atom. Hence, DGDFT combines the key advantage of planewave basis sets in terms of systematic improvability with that of localized basis sets in reducing basis size. A central issue for large-scale calculations, however, is the computation of the electron density from the discretized Hamiltonian in an efficient and scalable manner. We show in this work how Chebyshev polynomial filtered subspace iteration (CheFSI) can be used to address this issue and push the envelope in large-scale materials si...
National Aeronautics and Space Administration — The problem of estimating the aerodynamic models for flight control of damaged aircraft using an innovative differential vortex lattice method tightly coupled with...
National Aeronautics and Space Administration — Estimation of aerodynamic models for the control of damaged aircraft using an innovative differential vortex lattice method tightly coupled with an extended Kalman...
Nonmonotonic Recursive Polynomial Expansions for Linear Scaling Calculation of the Density Matrix.
Rubensson, Emanuel H
2011-05-10
As it stands, density matrix purification is a powerful tool for linear scaling electronic structure calculations. The convergence is rapid and depends only weakly on the band gap. However, as will be shown in this letter, there is room for improvements. The key is to allow for nonmonotonicity in the recursive polynomial expansion. On the basis of this idea, new purification schemes are proposed that require only half the number of matrix-matrix multiplications compared to previous schemes. The speedup is essentially independent of the location of the chemical potential and increases with decreasing band gap.
Non-monotonicity in the quantum-classical transition: Chaos induced by quantum effects
Kapulkin, A; Kapulkin, Arie; Pattanayak, Arjendu K.
2007-01-01
The transition from classical to quantum behavior for chaotic systems is understood to be accompanied by the suppression of chaotic effects as the relative size of $\\hbar$ is increased. We show evidence to the contrary in the behavior of the quantum trajectory dynamics of a dissipative quantum chaotic system, the double-well Duffing oscillator. The classical limit in the case considered has regular behavior, but as the effective $\\hbar$ is increased we see chaotic behavior. This chaos then disappears deeper into the quantum regime, which means that the quantum-classical transition in this case is non-monotonic in $\\hbar$.
Song, Z. Q.; Ni, Y.; Peng, L. M.; Liang, H. Y.; He, L. H.
2016-03-01
Bioinspired discontinuous nanolaminate design becomes an efficient way to mitigate the strength-ductility tradeoff in brittle materials via arresting the crack at the interface followed by controllable interface failure. The analytical solution and numerical simulation based on the nonlinear shear-lag model indicates that propagation of the interface failure can be unstable or stable when the interfacial shear stress between laminae is uniform or highly localized, respectively. A dimensionless key parameter defined by the ratio of two characteristic lengths governs the transition between the two interface-failure modes, which can explain the non-monotonic size-dependent mechanical properties observed in various laminate composites.
Wei, Xiaodan; Liu, Lijun; Zhou, Wenshu
2017-03-01
In this paper, we study the global stability and attractivity of the endemic equilibrium for a network-based SIS epidemic model with nonmonotone incidence rate. The model was introduced in Li (2015). We prove that the endemic equilibrium is globally asymptotically stable if α (a parameter of this model) is sufficiently large, and is globally attractive if the transmission rate λ satisfies λ/λc ∈(1 , 2 ] , where λc is the epidemic threshold. Some numerical experiments are also presented to illustrate the theoretical results.
Cusenza, Monica; Accardo, Agostino; Monti, Fabrizio; Bramanti, Placido
2010-01-01
Simultaneous EEG-fMRI is a powerful emerging tool in functional neuroimaging that exploits the relationship between neuronal electrophysiological activity and its hemodynamic response. It has found application in the study of both spontaneous and evoked brain activity. Combining the complementary advantages of the two techniques it provides a measurement with high temporal and spatial resolution, allowing a reliable localization of event generators. However, EEG data recorded inside MRI scanner are heavily corrupted by different types of artifacts due to the interactions between the patient, EEG electrodes wires and the magnetic fields inside the scanner. In particular, gradient switching and RF pulses, necessary to acquire fMRI data, generate large artifacts that can completely obscure EEG signals. Many methods have been proposed to eliminate or at least reduce gradient artifact. In this paper both a qualitative and a quantitative evaluation of two different algorithms used for gradient artifact removal are presented. Linear and non-linear characteristics of EEG, such as power spectra, fractal dimension and beta scaling exponent, are evaluated for EEGs recorded outside and inside the scanner, in MR static and dynamic conditions. The study highlights how residual artifacts after correction and artifacts induced by correction itself could still considerably affect EEG signals. The results suggest that the quality of both these gradient artifact filtering methods is not yet sufficient to preserve EEG characteristics and thus it must be further improved. The aim of this study is to make neurophysiologists aware of the filtering effects that can compromise linear and non-linear analysis of EEG recorded during functional MRI.