Anderson, Brian D O
2005-01-01
This graduate-level text augments and extends beyond undergraduate studies of signal processing, particularly in regard to communication systems and digital filtering theory. Vital for students in the fields of control and communications, its contents are also relevant to students in such diverse areas as statistics, economics, bioengineering, and operations research.Topics include filtering, linear systems, and estimation; the discrete-time Kalman filter; time-invariant filters; properties of Kalman filters; computational aspects; and smoothing of discrete-time signals. Additional subjects e
Institute of Scientific and Technical Information of China (English)
Xuehua Ye; Yaoju Zhang; Junfeng Chen
2007-01-01
In solid immersion lens (SIL) microscopy systems with high numerical aperture (NA), there always exists the aberration produced by Fresnel effects at the interface between SIL and the sample. This aberration may cause the degradation of the image of sample. We design a continuous phase filter and optimize the optical field distribution of SIL system. The numerical results show that when the continuous phase filter is used, the field distribution of SIL system can be optimized, and the focal depth and intensity of transmitted light can be increased. At the same time, the intensity of side-lobe and the resolution are kept almost unchanged.
Filters in topology optimization
DEFF Research Database (Denmark)
Bourdin, Blaise
1999-01-01
In this article, a modified (``filtered'') version of the minimum compliance topology optimization problem is studied. The direct dependence of the material properties on its pointwise density is replaced by a regularization of the density field using a convolution operator. In this setting...... it is possible to establish the existence of solutions. Moreover, convergence of an approximation by means of finite elements can be obtained. This is illustrated through some numerical experiments. The ``filtering'' technique is also shown to cope with two important numerical problems in topology optimization...
Filters in topology optimization
DEFF Research Database (Denmark)
Bourdin, Blaise
1999-01-01
In this article, a modified (``filtered'') version of the minimum compliance topology optimization problem is studied. The direct dependence of the material properties on its pointwise density is replaced by a regularization of the density field using a convolution operator. In this setting...... it is possible to establish the existence of solutions. Moreover, convergence of an approximation by means of finite elements can be obtained. This is illustrated through some numerical experiments. The ``filtering'' technique is also shown to cope with two important numerical problems in topology optimization...
Plasma grid design for optimized filter field configuration for the NBI test facility ELISE
Energy Technology Data Exchange (ETDEWEB)
Nocentini, R. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, D-85740 Garching (Germany)], E-mail: riccardo.nocentini@ipp.mpg.de; Gutser, R.; Heinemann, B.; Froeschle, M.; Riedl, R. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, D-85740 Garching (Germany)
2009-12-15
Maintenance-free RF sources for negative hydrogen ions with moderate extraction areas (100-200 cm{sup 2}) have been successfully developed in the last years at IPP Garching in the test facilities BATMAN and MANITU. A facility with larger extraction area (1000 cm{sup 2}), ELISE, is being designed with a 'half-size' ITER-like extraction system, pulsed ion acceleration up to 60 kV for 10 s and plasma generation up to 1 h. Due to the large size of the source, the magnetic filter field (FF) cannot be produced solely by permanent magnets. Therefore, an additional magnetic field produced by current flowing through the plasma grid (PG current) is required. The filter field homogeneity and the interaction with the electron suppression magnetic field have been studied in detail by finite element method (FEM) during the ELISE design phase. Significant improvements regarding the field homogeneity have been introduced compared to the ITER reference design. Also, for the same PG current a 50% higher field in front of the grid has been achieved by optimizing the plasma grid geometry. Hollow spaces have been introduced in the plasma grid for a more homogeneous PG current distribution. The introduction of hollow spaces also allows the insertion of permanent magnets in the plasma grid.
Liu, Dong; Miller, Ian; Hostetler, Chris; Cook, Anthony; Hair, Johnathan
2011-06-01
High spectral resolution lidars (HSRLs) have recently shown great value in aerosol measurements form aircraft and are being called for in future space-based aerosol remote sensing applications. A quasi-monolithic field-widened, off-axis Michelson interferometer had been developed as the spectral discrimination filter for an HSRL currently under development at NASA Langley Research Center (LaRC). The Michelson filter consists of a cubic beam splitter, a solid arm and an air arm. The input light is injected at 1.5° off-axis to provide two output channels: standard Michelson output and the reflected complementary signal. Piezo packs connect the air arm mirror to the main part of the filter that allows it to be tuned within a small range. In this paper, analyses of the throughput wavephase, locking error, AR coating, and tilt angle of the interferometer are described. The transmission ratio for monochromatic light at the transmitted wavelength is used as a figure of merit for assessing each of these parameters.
A Controlled Particle Filter for Global Optimization
Zhang, Chi; Taghvaei, Amirhossein; Mehta, Prashant G.
2017-01-01
A particle filter is introduced to numerically approximate a solution of the global optimization problem. The theoretical significance of this work comes from its variational aspects: (i) the proposed particle filter is a controlled interacting particle system where the control input represents the solution of a mean-field type optimal control problem; and (ii) the associated density transport is shown to be a gradient flow (steepest descent) for the optimal value function, with respect to th...
Optimal Multiobjective Design of Digital Filters Using Taguchi Optimization Technique
Ouadi, Abderrahmane; Bentarzi, Hamid; Recioui, Abdelmadjid
2014-01-01
The multiobjective design of digital filters using the powerful Taguchi optimization technique is considered in this paper. This relatively new optimization tool has been recently introduced to the field of engineering and is based on orthogonal arrays. It is characterized by its robustness, immunity to local optima trapping, relative fast convergence and ease of implementation. The objectives of filter design include matching some desired frequency response while having minimum linear phase; hence, reducing the time response. The results demonstrate that the proposed problem solving approach blended with the use of the Taguchi optimization technique produced filters that fulfill the desired characteristics and are of practical use.
Optimization of integrated polarization filters
Gagnon, Denis; Déziel, Jean-Luc; Dubé, Louis J
2014-01-01
This study reports on the design of small footprint, integrated polarization filters based on engineered photonic lattices. Using a rods-in-air lattice as a basis for a TE filter and a holes-in-slab lattice for the analogous TM filter, we are able to maximize the degree of polarization of the output beams up to 98 % with a transmission efficiency greater than 75 %. The proposed designs allow not only for logical polarization filtering, but can also be tailored to output an arbitrary transverse beam profile. The lattice configurations are found using a recently proposed parallel tabu search algorithm for combinatorial optimization problems in integrated photonics.
Optimal Filtering of Malicious IP Sources
Soldo, Fabio; Argyraki, Katerina
2008-01-01
How can we protect the network infrastructure from malicious traffic, such as scanning, malicious code propagation, and distributed denial-of-service (DDoS) attacks? One mechanism for blocking malicious traffic is filtering: access control lists (ACLs) can selectively block traffic based on fields of the IP header. Filters (ACLs) are already available in the routers today but are a scarce resource because they are stored in the expensive ternary content addressable memory (TCAM). In this paper, we develop, for the first time, a framework for studying filter selection as a resource allocation problem. Within this framework, we study five practical cases of source address/prefix filtering, which correspond to different attack scenarios and operator's policies. We show that filter selection optimization leads to novel variations of the multidimensional knapsack problem and we design optimal, yet computationally efficient, algorithms to solve them. We also evaluate our approach using data from Dshield.org and dem...
Optimal Nonlinear Filter for INS Alignment
Institute of Scientific and Technical Information of China (English)
赵瑞; 顾启泰
2002-01-01
All the methods to handle the inertial navigation system (INS) alignment were sub-optimal in the past. In this paper, particle filtering (PF) as an optimal method is used for solving the problem of INS alignment. A sub-optimal two-step filtering algorithm is presented to improve the real-time performance of PF. The approach combines particle filtering with Kalman filtering (KF). Simulation results illustrate the superior performance of these approaches when compared with extended Kalman filtering (EKF).
Topology optimization of microwave waveguide filters
Aage, Niels
2016-01-01
We present a density based topology optimization approach for the design of metallic microwave insert filters. A two-phase optimization procedure is proposed in which we, starting from a uniform design, first optimize to obtain a set of spectral varying resonators followed by a band gap optimization for the desired filter characteristics. This is illustrated through numerical experiments and comparison to a standard band pass filter design. It is seen that the carefully optimized topologies can sharpen the filter characteristics and improve performance. Furthermore, the obtained designs share little resemblance to standard filter layouts and hence the proposed design method offers a new design tool in microwave engineering.
Satisfactory Optimization Design of IIR Digital Filters
Institute of Scientific and Technical Information of China (English)
Jin Weidong; Zhang Gexiang; Zhao Duo
2005-01-01
A new method called satisfactory optimization method is proposed to design IIR (Infinite Impulse Response) digital filters, and the satisfactory optimization model is presented. The detailed algorithm of designing IIR digital filters using satisfactory optimization method is described. By using quantum genetic algorithm characterized by rapid convergence and good global search capability, the satisfying solutions are achieved in the experiment of designing lowpass and bandpass IIR digital filters. Experimental results show that the performances of IIR filters designed by the introduced method are better than those by traditional methods.
Moonen, Dominicus Johannes Guilielmus; Buesink, Frederik Johannes Karel; Leferink, Frank Bernardus Johannes
2016-01-01
To reduce common mode(CM) and differential mode(DM) interference, a DM/CM integrated filter is often required to reduce the level of interference. This paper will show coupling from a Common Mode Choke(CMC) into Cx capacitors can decrease the DM-filtering performance significantly at high
Model based optimization of EMC input filters
Energy Technology Data Exchange (ETDEWEB)
Raggl, K; Kolar, J. W. [Swiss Federal Institute of Technology, Power Electronic Systems Laboratory, Zuerich (Switzerland); Nussbaumer, T. [Levitronix GmbH, Zuerich (Switzerland)
2008-07-01
Input filters of power converters for compliance with regulatory electromagnetic compatibility (EMC) standards are often over-dimensioned in practice due to a non-optimal selection of number of filter stages and/or the lack of solid volumetric models of the inductor cores. This paper presents a systematic filter design approach based on a specific filter attenuation requirement and volumetric component parameters. It is shown that a minimal volume can be found for a certain optimal number of filter stages for both the differential mode (DM) and common mode (CM) filter. The considerations are carried out exemplarily for an EMC input filter of a single phase power converter for the power levels of 100 W, 300 W, and 500 W. (author)
GNSS data filtering optimization for ionospheric observation
D'Angelo, G.; Spogli, L.; Cesaroni, C.; Sgrigna, V.; Alfonsi, L.; Aquino, M. H. O.
2015-12-01
In the last years, the use of GNSS (Global Navigation Satellite Systems) data has been gradually increasing, for both scientific studies and technological applications. High-rate GNSS data, able to generate and output 50-Hz phase and amplitude samples, are commonly used to study electron density irregularities within the ionosphere. Ionospheric irregularities may cause scintillations, which are rapid and random fluctuations of the phase and the amplitude of the received GNSS signals. For scintillation analysis, usually, GNSS signals observed at an elevation angle lower than an arbitrary threshold (usually 15°, 20° or 30°) are filtered out, to remove the possible error sources due to the local environment where the receiver is deployed. Indeed, the signal scattered by the environment surrounding the receiver could mimic ionospheric scintillation, because buildings, trees, etc. might create diffusion, diffraction and reflection. Although widely adopted, the elevation angle threshold has some downsides, as it may under or overestimate the actual impact of multipath due to local environment. Certainly, an incorrect selection of the field of view spanned by the GNSS antenna may lead to the misidentification of scintillation events at low elevation angles. With the aim to tackle the non-ionospheric effects induced by multipath at ground, in this paper we introduce a filtering technique, termed SOLIDIFY (Standalone OutLiers IDentIfication Filtering analYsis technique), aiming at excluding the multipath sources of non-ionospheric origin to improve the quality of the information obtained by the GNSS signal in a given site. SOLIDIFY is a statistical filtering technique based on the signal quality parameters measured by scintillation receivers. The technique is applied and optimized on the data acquired by a scintillation receiver located at the Istituto Nazionale di Geofisica e Vulcanologia, in Rome. The results of the exercise show that, in the considered case of a noisy
Automatic Target Detection by Optimal Morphological Filters
Institute of Scientific and Technical Information of China (English)
YU Nong(余农); WU Hao(吴昊); WU ChangYong(吴常泳); LI YuShu(李予蜀)
2003-01-01
It is widely accepted that the design of morphological filters, which are optimal in some sense, is a difficult task. In this paper a novel method for optimal learning of morphological filtering parameters (Genetic training algorithm for morphological filters, GTAMF) is presented.GTAMF adopts new crossover and mutation operators called the curved cylinder crossover and master-slave mutation to achieve optimal filtering parameters in a global searching. Experimental results show that this method is practical, easy to extend, and markedly improves the performances of morphological filters. The operation of a morphological filter can be divided into two basic problems including morphological operation and structuring element (SE) selection. The rules for morphological operations are predefined so that the filter's properties depend merely on the selection of SE. By means of adaptive optimization training, structuring elements possess the shape and structural characteristics of image targets, and give specific information to SE. Morphological filters formed in this way become certainly intelligent and can provide good filtering results and robust adaptability to image targets with clutter background.
Topology optimization of microwave waveguide filters
DEFF Research Database (Denmark)
Aage, Niels; Johansen, Villads Egede
2017-01-01
We present a density based topology optimization approach for the design of metallic microwave insert filters. A two-phase optimization procedure is proposed in which we, starting from a uniform design, first optimize to obtain a set of spectral varying resonators followed by a band gap optimizat......We present a density based topology optimization approach for the design of metallic microwave insert filters. A two-phase optimization procedure is proposed in which we, starting from a uniform design, first optimize to obtain a set of spectral varying resonators followed by a band gap...... little resemblance to standard filter layouts and hence the proposed design method offers a new design tool in microwave engineering....
Discrete stochastic processes and optimal filtering
Bertein, Jean-Claude
2012-01-01
Optimal filtering applied to stationary and non-stationary signals provides the most efficient means of dealing with problems arising from the extraction of noise signals. Moreover, it is a fundamental feature in a range of applications, such as in navigation in aerospace and aeronautics, filter processing in the telecommunications industry, etc. This book provides a comprehensive overview of this area, discussing random and Gaussian vectors, outlining the results necessary for the creation of Wiener and adaptive filters used for stationary signals, as well as examining Kalman filters which ar
Mukhopadhyay, Somparna; Hazra, Lakshminarayan
2015-11-01
Resolution capability of an optical imaging system can be enhanced by reducing the width of the central lobe of the point spread function. Attempts to achieve the same by pupil plane filtering give rise to a concomitant increase in sidelobe intensity. The mutual exclusivity between these two objectives may be considered as a multiobjective optimization problem that does not have a unique solution; rather, a class of trade-off solutions called Pareto optimal solutions may be generated. Pareto fronts in the synthesis of lossless phase-only pupil plane filters to achieve superresolution with prespecified lower limits for the Strehl ratio are explored by using the particle swarm optimization technique.
Desensitized Optimal Filtering and Sensor Fusion Toolkit
Karlgaard, Christopher D.
2015-01-01
Analytical Mechanics Associates, Inc., has developed a software toolkit that filters and processes navigational data from multiple sensor sources. A key component of the toolkit is a trajectory optimization technique that reduces the sensitivity of Kalman filters with respect to model parameter uncertainties. The sensor fusion toolkit also integrates recent advances in adaptive Kalman and sigma-point filters for non-Gaussian problems with error statistics. This Phase II effort provides new filtering and sensor fusion techniques in a convenient package that can be used as a stand-alone application for ground support and/or onboard use. Its modular architecture enables ready integration with existing tools. A suite of sensor models and noise distribution as well as Monte Carlo analysis capability are included to enable statistical performance evaluations.
Desensitized Optimal Filtering and Sensor Fusion Tool Kit Project
National Aeronautics and Space Administration — Research on desensitized optimal filtering techniques and a navigation and sensor fusion tool kit using advanced filtering techniques is proposed. Research focuses...
Outbound SPIT Filter with Optimal Performance Guarantees
Jung, Tobias; Nassar, Mohamed; Ernst, Damien; Leduc, Guy
2012-01-01
This paper presents a formal framework for identifying and filtering SPIT calls (SPam in Internet Telephony) in an outbound scenario with provable optimal performance. In so doing, our work is largely different from related previous work: our goal is to rigorously formalize the problem in terms of mathematical decision theory, find the optimal solution to the problem, and derive concrete bounds for its expected loss (number of mistakes the SPIT filter will make in the worst case). This goal is achieved by considering an abstracted scenario amenable to theoretical analysis, namely SPIT detection in an outbound scenario with pure sources. Our methodology is to first define the cost of making an error (false positive and false negative), apply Wald's sequential probability ratio test to the individual sources, and then determine analytically error probabilities such that the resulting expected loss is minimized. The benefits of our approach are: (1) the method is optimal (in a sense defined in the paper); (2) th...
On filter boundary conditions in topology optimization
DEFF Research Database (Denmark)
Clausen, Anders; Andreassen, Erik
2017-01-01
we define three requirements that boundary conditions must fulfill in order to eliminate boundary effects. Previously suggested approaches are briefly reviewed in the light of these requirements. A new approach referred to as the “domain extension approach” is suggested. It effectively eliminates......Most research papers on topology optimization involve filters for regularization. Typically, boundary effects from the filters are ignored. Despite significant drawbacks the inappropriate homogeneous Neumann boundary conditions are used, probably because they are trivial to implement. In this paper...
When "Optimal Filtering" Isn't
Fowler, J W; Doriese, W B; Hays-Wehle, J; Joe, Y -I; Morgan, K M; O'Neil, G C; Reintsema, C D; Schmidt, D R; Ullom, J N; Swetz, D S
2016-01-01
The so-called "optimal filter" analysis of a microcalorimeter's x-ray pulses is statistically optimal only if all pulses have the same shape, regardless of energy. The shapes of pulses from a nonlinear detector can and do depend on the pulse energy, however. A pulse-fitting procedure that we call "tangent filtering" accounts for the energy dependence of the shape and should therefore achieve superior energy resolution. We take a geometric view of the pulse-fitting problem and give expressions to predict how much the energy resolution stands to benefit from such a procedure. We also demonstrate the method with a case study of K-line fluorescence from several 3d transition metals. The method improves the resolution from 4.9 eV to 4.2 eV at the Cu K$\\alpha$ line (8.0keV).
Image Filtering with Field Programmable Gate Array
Directory of Open Access Journals (Sweden)
Arūnas Šlenderis
2013-05-01
Full Text Available The research examined the use of field programmable gate arrays (FPGA in image filtering. Experimental and theoretical researches were reviewed. Experiments with Cyclone III family FPGA chip with implemented NIOS II soft processor were considered. Image filtering was achieved with symmetrical and asymmetrical finite impulse response filters with convolution kernel. The system, which was implemented with 3×3 symmetrical filter, which was implemented using the hardware description language, uses 59% of logic elements of the chip and 10 multiplication elements. The system with asymmetrical filter uses the same amount of logic elements and 13 multiplication elements. Both filter systems consume approx. 545 mW of power. The system, which is designed for filter implementation in C language, uses 65% of all logical elements and consumes 729 mW of power.Article in Lithuanian
Field of Particle Filters Image Inpainting
DEFF Research Database (Denmark)
Cuzol, Anne; Pedersen, Kim Steenstrup; Nielsen, Mads
2008-01-01
We present a novel algorithm for solving the image inpainting problem based on a field of locally interacting particle filters. Image inpainting, also known as image completion, is concerned with the problem of filling image regions with new visually plausible data. In order to avoid the difficulty...... of solving the problem globally for the region to be inpainted, we introduce a field of local particle filters. The states of the particle filters are image patches. Global consistency is enforced by a Markov random field image model which connects neighbouring particle filters. The benefit of using locally...... interacting particle filters is that several competing hypotheses on inpainting solutions are kept active, allowing the method to provide globally consistent solutions on problems where other local methods may fail. We provide examples of applications of the developed method. Keywords: Inpainting · Image...
FUZZY OPTIMIZATION USING EXTENDED KALMAN FILTER
Directory of Open Access Journals (Sweden)
M.DIVYA
2013-01-01
Full Text Available Fuzzy Logic is based on the idea that in fuzzy sets each element in the set can assume a value from 0 to 1, not only 0 or 1, as in crisp set theory. The degree of membership function is defined as the gradation in the extent to which an element is belonging to the relevant sets. Optimizing the membership functions of a fuzzy system can be viewed as a system identification problem for nonlinear dynamic system. In this paper two input and one output fuzzy controller is designed for the dynamic process of aircraft. The addition of an EKF in the feedback loop improved the system response by blocking possible effects of measurement error based on Predictor-Corrector algorithm. An Extended Kalman Filter approach to optimize the membership functions of the inputs and outputs of the fuzzy controller. The performance of the fuzzy system before and after the optimization are compared, as well as the membership functions.
On optimal filtering of measured Mueller matrices
Gil, Jose J
2016-01-01
While any two-dimensional mixed state of polarization of light can be represented by a combination of a pure state and a fully random state, any Mueller matrix can be represented by a convex combination of a pure component and three additional components whose randomness is scaled in a proper and objective way. Such characteristic decomposition constitutes the appropriate framework for the characterization of the polarimetric randomness of the system represented by a given Mueller matrix, and provides appropriate criteria for the optimal filtering of noise in experimental polarimetry.
Consensus+Innovations Distributed Kalman Filter With Optimized Gains
Das, Subhro; Moura, Jose M. F.
2017-01-01
In this paper, we address the distributed filtering and prediction of time-varying random fields represented by linear time-invariant (LTI) dynamical systems. The field is observed by a sparsely connected network of agents/sensors collaborating among themselves. We develop a Kalman filter type consensus+innovations distributed linear estimator of the dynamic field termed as Consensus+Innovations Kalman Filter. We analyze the convergence properties of this distributed estimator. We prove that the mean-squared error of the estimator asymptotically converges if the degree of instability of the field dynamics is within a pre-specified threshold defined as tracking capacity of the estimator. The tracking capacity is a function of the local observation models and the agent communication network. We design the optimal consensus and innovation gain matrices yielding distributed estimates with minimized mean-squared error. Through numerical evaluations, we show that, the distributed estimator with optimal gains converges faster and with approximately 3dB better mean-squared error performance than previous distributed estimators.
Electrostatic air filters generated by electric fields
Energy Technology Data Exchange (ETDEWEB)
Bergman, W.; Biermann, A.H.; Hebard, H.D.; Lum, B.Y.; Kuhl, W.D.
1981-01-27
This paper presents theoretical and experimental findings on fibrous filters converted to electrostatic operation by a nonionizing electric field. Compared to a conventional fibrous filter, the electrostatic filter has a higher efficiency and a longer, useful life. The increased efficiency is attributed to a time independent attraction between polarized fibers and charged, polarized particles and a time dependent attraction between charged fibers and charged, polarized particles. The charge on the fibers results from a dynamic process of charge accumulation due to the particle deposits and a charge dissipation due to the fiber conductivity.
Linearity optimization of edge filter demodulators in FBGs
Li, Dong-Sheng; Sui, Qing-Mei; Cao, Yu-Qiang
2008-05-01
A kind of electric circuit is improved to optimize the linearity of edge filter demodulators in FBGs. By using a logarithm amplifier and an extraction operation, the linear range of optimized edge filter demodulators has been broadened effectively, and the requirement of optical filter’s linear range has been reduced. Theoretical analyses and the simulation results indicated that the linear range of optimized edge filter demodulator’s covers the whole transition region of the edge filter, while a strict linearity of the optical filter is not necessary.
Optimized object tracking technique using Kalman filter
Directory of Open Access Journals (Sweden)
Liana Ellen Taylor
2016-07-01
Full Text Available This paper focused on the design of an optimized object tracking technique which would minimize the processing time required in the object detection process while maintaining accuracy in detecting the desired moving object in a cluttered scene. A Kalman filter based cropped image is used for the image detection process as the processing time is significantly less to detect the object when a search window is used that is smaller than the entire video frame. This technique was tested with various sizes of the window in the cropping process. MATLAB® was used to design and test the proposed method. This paper found that using a cropped image with 2.16 multiplied by the largest dimension of the object resulted in significantly faster processing time while still providing a high success rate of detection and a detected center of the object that was reasonably close to the actual center.
Topology Optimization - Improved Checker-Board Filtering With Sharp Contours
DEFF Research Database (Denmark)
Pedersen, Christian Gejl; Lund, Jeppe Jessen; Damkilde, Lars
2006-01-01
In topology optimization it is mandatory to use a filtering technique in order to prevent checker-boarder solutions. The paper examines a new filtering principle and demonstrates an improved sharpness in the contours. This was not realized in the original proposal of the filter. Furthermore...
Optimized multichannel decomposition for texture segmentation using Gabor filter bank
Nezamoddini-Kachouie, Nezamoddin; Alirezaie, Javad
2004-05-01
Texture segmentation and analysis is an important aspect of pattern recognition and digital image processing. Previous approaches to texture analysis and segmentation perform multi-channel filtering by applying a set of filters to the image. In this paper we describe a texture segmentation algorithm based on multi-channel filtering that is optimized using diagonal high frequency residual. Gabor band pass filters with different radial spatial frequencies and different orientations have optimum resolution in time and frequency domain. The image is decomposed by a set of Gabor filters into a number of filtered images; each one contains variation of intensity on a sub-band frequency and orientation. The features extracted by Gabor filters have been applied for image segmentation and analysis. There are some important considerations about filter parameters and filter bank coverage in frequency domain. This filter bank does not completely cover the corners of the frequency domain along the diagonals. In our method we optimize the spatial implementation for the Gabor filter bank considering the diagonal high frequency residual. Segmentation is accomplished by a feedforward backpropagation multi-layer perceptron that is trained by optimized extracted features. After MLP is trained the input image is segmented and each pixel is assigned to the proper class.
A Low Cost Structurally Optimized Design for Diverse Filter Types.
Kazmi, Majida; Aziz, Arshad; Akhtar, Pervez; Ikram, Nassar
2016-01-01
A wide range of image processing applications deploys two dimensional (2D)-filters for performing diversified tasks such as image enhancement, edge detection, noise suppression, multi scale decomposition and compression etc. All of these tasks require multiple type of 2D-filters simultaneously to acquire the desired results. The resource hungry conventional approach is not a viable option for implementing these computationally intensive 2D-filters especially in a resource constraint environment. Thus it calls for optimized solutions. Mostly the optimization of these filters are based on exploiting structural properties. A common shortcoming of all previously reported optimized approaches is their restricted applicability only for a specific filter type. These narrow scoped solutions completely disregard the versatility attribute of advanced image processing applications and in turn offset their effectiveness while implementing a complete application. This paper presents an efficient framework which exploits the structural properties of 2D-filters for effectually reducing its computational cost along with an added advantage of versatility for supporting diverse filter types. A composite symmetric filter structure is introduced which exploits the identities of quadrant and circular T-symmetries in two distinct filter regions simultaneously. These T-symmetries effectually reduce the number of filter coefficients and consequently its multipliers count. The proposed framework at the same time empowers this composite filter structure with additional capabilities of realizing all of its Ψ-symmetry based subtypes and also its special asymmetric filters case. The two-fold optimized framework thus reduces filter computational cost up to 75% as compared to the conventional approach as well as its versatility attribute not only supports diverse filter types but also offers further cost reduction via resource sharing for sequential implementation of diversified image
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.
Non-linear DSGE Models and The Optimized Particle Filter
DEFF Research Database (Denmark)
Andreasen, Martin Møller
This paper improves the accuracy and speed of particle filtering for non-linear DSGE models with potentially non-normal shocks. This is done by introducing a new proposal distribution which i) incorporates information from new observables and ii) has a small optimization step that minimizes...... the distance to the optimal proposal distribution. A particle filter with this proposal distribution is shown to deliver a high level of accuracy even with relatively few particles, and this filter is therefore much more efficient than the standard particle filter....
Gabor Filter Optimization Design for Iris Texture Analysis
Institute of Scientific and Technical Information of China (English)
Tao Xu; Xing Ming; Xiaoguang Yang
2004-01-01
This paper deals with an optimization design method for the Gabor filters based on the analysis of an iris texture model. By means of analyzing the properties of an iris texture image, the energy distribution regularity of the iris texture image measured by the average power spectrum density is exploited, and the theoretical ranges of the efficient valued frequency and orientation parameters can also be deduced. The analysis shows that the energy distribution of the iris texture is generally centralized around lower frequencies in the spatial frequency domain. Accordingly, an iterative algorithm is designed to optimize the Gabor parameter field. The experimental results indicate the validity of the theory and efficiency of the algorithm.
Deterministic Mean-Field Ensemble Kalman Filtering
Law, Kody J. H.
2016-05-03
The proof of convergence of the standard ensemble Kalman filter (EnKF) from Le Gland, Monbet, and Tran [Large sample asymptotics for the ensemble Kalman filter, in The Oxford Handbook of Nonlinear Filtering, Oxford University Press, Oxford, UK, 2011, pp. 598--631] is extended to non-Gaussian state-space models. A density-based deterministic approximation of the mean-field limit EnKF (DMFEnKF) 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 dimension d<2k. The fidelity of approximation of the true distribution is also established using an extension of the total variation metric to random measures. This is limited by a Gaussian bias term arising from nonlinearity/non-Gaussianity of the model, which arises in both deterministic and standard EnKF. Numerical results support and extend the theory.
Optimal filter bandwidth for pulse oximetry
Stuban, Norbert; Niwayama, Masatsugu
2012-10-01
Pulse oximeters contain one or more signal filtering stages between the photodiode and microcontroller. These filters are responsible for removing the noise while retaining the useful frequency components of the signal, thus improving the signal-to-noise ratio. The corner frequencies of these filters affect not only the noise level, but also the shape of the pulse signal. Narrow filter bandwidth effectively suppresses the noise; however, at the same time, it distorts the useful signal components by decreasing the harmonic content. In this paper, we investigated the influence of the filter bandwidth on the accuracy of pulse oximeters. We used a pulse oximeter tester device to produce stable, repetitive pulse waves with digitally adjustable R ratio and heart rate. We built a pulse oximeter and attached it to the tester device. The pulse oximeter digitized the current of its photodiode directly, without any analog signal conditioning. We varied the corner frequency of the low-pass filter in the pulse oximeter in the range of 0.66-15 Hz by software. For the tester device, the R ratio was set to R = 1.00, and the R ratio deviation measured by the pulse oximeter was monitored as a function of the corner frequency of the low-pass filter. The results revealed that lowering the corner frequency of the low-pass filter did not decrease the accuracy of the oxygen level measurements. The lowest possible value of the corner frequency of the low-pass filter is the fundamental frequency of the pulse signal. We concluded that the harmonics of the pulse signal do not contribute to the accuracy of pulse oximetry. The results achieved by the pulse oximeter tester were verified by human experiments, performed on five healthy subjects. The results of the human measurements confirmed that filtering out the harmonics of the pulse signal does not degrade the accuracy of pulse oximetry.
Practice Utilization of Algorithms for Analog Filter Group Delay Optimization
Directory of Open Access Journals (Sweden)
K. Hajek
2007-04-01
Full Text Available This contribution deals with an application of three different algorithms which optimize a group delay of analog filters. One of them is a part of the professional circuit simulator Micro Cap 7 and the others two original algorithms are developed in the MATLAB environment. An all-pass network is used to optimize the group delay of an arbitrary analog filter. Introduced algorithms look for an optimal order and optimal coefficients of an all-pass network transfer function. Theoretical foundations are introduced and all algorithms are tested using the optimization of testing analog filter. The optimization is always run three times because the second, third and fourth-order all-pass network is used. An equalization of the original group delay is a main objective of these optimizations. All outputs of all algorithms are critically evaluated and also described.
Evolutionary Dynamic Multiobjective Optimization Via Kalman Filter Prediction.
Muruganantham, Arrchana; Tan, Kay Chen; Vadakkepat, Prahlad
2016-12-01
Evolutionary algorithms are effective in solving static multiobjective optimization problems resulting in the emergence of a number of state-of-the-art multiobjective evolutionary algorithms (MOEAs). Nevertheless, the interest in applying them to solve dynamic multiobjective optimization problems has only been tepid. Benchmark problems, appropriate performance metrics, as well as efficient algorithms are required to further the research in this field. One or more objectives may change with time in dynamic optimization problems. The optimization algorithm must be able to track the moving optima efficiently. A prediction model can learn the patterns from past experience and predict future changes. In this paper, a new dynamic MOEA using Kalman filter (KF) predictions in decision space is proposed to solve the aforementioned problems. The predictions help to guide the search toward the changed optima, thereby accelerating convergence. A scoring scheme is devised to hybridize the KF prediction with a random reinitialization method. Experimental results and performance comparisons with other state-of-the-art algorithms demonstrate that the proposed algorithm is capable of significantly improving the dynamic optimization performance.
Optimal Source-Based Filtering of Malicious Traffic
Soldo, Fabio; Markopoulou, Athina
2010-01-01
In this paper, we consider the problem of blocking malicious traffic on the Internet, via source-based filtering. In particular, we consider filtering via access control lists (ACLs): these are already available at the routers today but are a scarce resource because they are stored in the expensive ternary content addressable memory (TCAM). Aggregation (by filtering source prefixes instead of individual IP addresses) helps reduce the number of filters, but comes also at the cost of blocking legitimate traffic originating from the filtered prefixes. We show how to optimally choose which source prefixes to filter, for a variety of realistic attack scenarios and operators' policies. In each scenario, we design optimal, yet computationally efficient, algorithms. Using logs from Dshield.org, we evaluate the algorithms and demonstrate that they bring significant benefit in practice.
An Optimal Transport Formulation of the Linear Feedback Particle Filter
Taghvaei, Amirhossein; Mehta, Prashant G.
2015-01-01
Feedback particle filter (FPF) is an algorithm to numerically approximate the solution of the nonlinear filtering problem in continuous time. The algorithm implements a feedback control law for a system of particles such that the empirical distribution of particles approximates the posterior distribution. However, it has been noted in the literature that the feedback control law is not unique. To find a unique control law, the filtering task is formulated here as an optimal transportation pro...
Optimal multihump filter for photometric redshifts
Budavari, Tamas; Szalay, Alexander S.; Csabai, Istvan; Connolly, Andrew J.; Tsvetanov, Zlatan
2001-01-01
We propose a novel type filter for multicolor imaging to improve on the photometric redshift estimation of galaxies. An extra filter - specific to a certain photometric system - may be utilized with high efficiency. We present a case study of the Hubble Space Telescope's Advanced Camera for Surveys and show that one extra exposure could cut down the mean square error on photometric redshifts by 34% over the z
Optimization-based particle filter for state and parameter estimation
Institute of Scientific and Technical Information of China (English)
Li Fu; Qi Fei; Shi Guangming; Zhang Li
2009-01-01
In recent years, the theory of particle filter has been developed and widely used for state and parameter estimation in nonlinear/non-Gaussian systems. Choosing good importance density is a critical issue in particle filter design. In order to improve the approximation of posterior distribution, this paper provides an optimization-based algorithm (the steepest descent method) to generate the proposal distribution and then sample particles from the distribution. This algorithm is applied in 1-D case, and the simulation results show that the proposed particle filter performs better than the extended Kalman filter (EKF), the standard particle filter (PF), the extended Kalman particle filter (PF-EKF) and the unscented particle filter (UPF) both in efficiency and in estimation precision.
Desensitized Optimal Filtering and Sensor Fusion Tool Kit Project
National Aeronautics and Space Administration — It is proposed to develop desensitized optimal filtering techniques and to implement these algorithms in a navigation and sensor fusion tool kit. These proposed...
Optimizing internal structure of membrane filters
Cummings, Linda; Sanaei, Pejman
2016-11-01
Membrane filters are in widespread use, and manufacturers have considerable interest in improving their performance, in terms of particle retention properties, and total throughput over the filter lifetime. In this regard, it has long been known that membrane properties should not be uniform over the membrane depth; rather, membrane permeability should decrease in the direction of flow. While much research effort has been focused on investigating favorable membrane permeability gradients, this work has been largely empirical in nature. We present a simple, first-principles model for flow through and fouling of a membrane filter, accounting for permeability gradients via variable pore size. Our model accounts for two fouling modes: sieving; and particle adsorption within pores. For filtration driven by a fixed pressure drop, flux through the membrane eventually goes to zero, as fouling occurs and pores close. We address issues of filter performance as the internal pore structure is varied, by comparing the total throughput obtained with equal-resistance membranes. Within certain classes of pore profiles we are able to find the optimum pore profile that maximizes total throughput over the filter lifetime, while maintaining acceptable particle removal from the feed. Partial support from NSF DMS 1261596 is gratefully acknowledged.
Field Evaluation of the Sidestream Sensors for Filter/Separators and Clay Filters.
1987-02-01
Report No. 552 OTC FILE COPY S ApOV FOR pffBU WAMES DISTRIBUTION UNUMITED FIELD EVALUATION OF THE SIDESTREAM SENSORS FOR FILTER/SEPARATORS AND CLAY FILTERS...SIDESTREA SENSORS FOR FILTER/SEPARATORS AND CLAY FILTERS (CRC PROJECT No. CA-47-70) IN FORMULATING AND APPROVING REPCRTS, THE APPROPRIATE COMMITTEE OF THE...noted that the filter/separator unit at Basle operated at an unusually high pressure drop. The deactivated coalescer was found to contain gummy
Optimal Sensor Decision Based on Particle Filter
Institute of Scientific and Technical Information of China (English)
XU Meng; WANG Hong-wei; HU Shi-qiang
2006-01-01
A novel infrared and radar synergistic tracking algorithm, which is based on the idea of closed loop control, and target's motion model identification and particle filter approach, was put forward. In order to improve the observability and filtering divergence of infrared search and tracking, the unscented Kalman filter algorithm that has stronger ability of non-linear approximation was adopted. The polynomial and least square method based on radar and IRST measurements to identify the parameters of the model was proposed, and a "pseudo sensor" was suggested to estimate the target position according to the identified model even if the radar is turned off. At last,the average Kullback-Leibler discrimination distance based on particle filter was used to measure the tracking performance, based on tracking performance and fuzzy stochastic decision, the idea of closed loop was used to retrieve the module parameter of "pseudo sensor". The experimental result indicates that the algorithm can not only limit the radar activity effectively but also keep the tracking accuracy of active/passive system well.
Optimal Sharpening of Compensated Comb Decimation Filters: Analysis and Design
Directory of Open Access Journals (Sweden)
David Ernesto Troncoso Romero
2014-01-01
Full Text Available Comb filters are a class of low-complexity filters especially useful for multistage decimation processes. However, the magnitude response of comb filters presents a droop in the passband region and low stopband attenuation, which is undesirable in many applications. In this work, it is shown that, for stringent magnitude specifications, sharpening compensated comb filters requires a lower-degree sharpening polynomial compared to sharpening comb filters without compensation, resulting in a solution with lower computational complexity. Using a simple three-addition compensator and an optimization-based derivation of sharpening polynomials, we introduce an effective low-complexity filtering scheme. Design examples are presented in order to show the performance improvement in terms of passband distortion and selectivity compared to other methods based on the traditional Kaiser-Hamming sharpening and the Chebyshev sharpening techniques recently introduced in the literature.
Non-linear and signal energy optimal asymptotic filter design
Directory of Open Access Journals (Sweden)
Josef Hrusak
2003-10-01
Full Text Available The paper studies some connections between the main results of the well known Wiener-Kalman-Bucy stochastic approach to filtering problems based mainly on the linear stochastic estimation theory and emphasizing the optimality aspects of the achieved results and the classical deterministic frequency domain linear filters such as Chebyshev, Butterworth, Bessel, etc. A new non-stochastic but not necessarily deterministic (possibly non-linear alternative approach called asymptotic filtering based mainly on the concepts of signal power, signal energy and a system equivalence relation plays an important role in the presentation. Filtering error invariance and convergence aspects are emphasized in the approach. It is shown that introducing the signal power as the quantitative measure of energy dissipation makes it possible to achieve reasonable results from the optimality point of view as well. The property of structural energy dissipativeness is one of the most important and fundamental features of resulting filters. Therefore, it is natural to call them asymptotic filters. The notion of the asymptotic filter is carried in the paper as a proper tool in order to unify stochastic and non-stochastic, linear and nonlinear approaches to signal filtering.
Mean-field Ensemble Kalman Filter
Law, Kody
2015-01-07
A proof of convergence of the standard EnKF generalized to non-Gaussian state space models is provided. A density-based deterministic approximation of the mean-field limiting EnKF (MFEnKF) is proposed, consisting of a PDE solver and a quadrature rule. Given a certain minimal order of convergence between the two, this extends to the deterministic filter approximation, which is therefore asymptotically superior to standard EnKF for d < 2 . 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.
Optimal Filtering in Pilot-Aided Carrier Recovery
Directory of Open Access Journals (Sweden)
Arnaldo Spalvieri
2009-01-01
Full Text Available The paper deals with carrier recovery based on pilot symbols in single-carrier systems. Wiener's method is used to determine the optimal unconstrained filter in estimation of phase noise assuming that a sequence of equally spaced pilot symbols is available. Our analysis allows to capture two effects that are not considered in the existing literature: the impact of aliasing due to sampling of the phase noise sequence at the pilot rate and the cyclostationary nature of the estimate hence of its performance. Experimental results are derived also for the case, where the filter is constrained to the cascade of two moving averages. These results show that, in the considered example, the mean-square phase error of the constrained filter is within 0.35 dB from the MSE of the optimal filter.
Design and performance optimization of fiber optic adaptive filters.
Paparao, P; Ghosh, A; Allen, S D
1991-05-10
There is a great need for easy-to-fabricate and versatile fiber optic signal processing systems in which optical fibers are used for the delay and storage of wideband guided lightwave signals. We describe the design of the least-mean-square algorithm-based fiber optic adaptive filters for processing guided lightwave signals in real time. Fiber optic adaptive filters can learn to change their parameters or to process a set of characteristics of the input signal. In our realization we employ as few electronic devices as possible and use optical computation to utilize the advantages of optics in the processing speed, parallelism, and interconnection. Many schemes for optical adaptive filtering of electronic signals are available in the literature. The new optical adaptive filters described in this paper are for optical processing of guided lightwave signals, not electronic signals. We analyzed the convergence or learning characteristics of the adaptive filtering process as a function of the filter parameters and the fiber optic hardware errors. From this analysis we found that the effects of the optical round-off errors and noise can be reduced, and the learning speed can be comparatively increased in our design through an optimal selection of the filter parameters. A general knowledge of the fiber optic hardware, the statistics of the lightwave signal, and the desired goal of the adaptive processing are enough for this optimum selection of the parameters. Detailed computer simulations validate the theoretical results of performance optimization.
Generating nonclassical quantum input field states with modulating filters
Energy Technology Data Exchange (ETDEWEB)
Gough, John E. [Aberystwyth University, Department of Physics, Aberystwyth, Wales (United Kingdom); Zhang, Guofeng [The Hong Kong Polytechnic University, Department of Applied Mathematics, Hong Kong (China)
2015-12-15
We give explicit constructions of quantum dynamical filters which generate nonclassical states (coherent states, cat states, shaped single and multi-photon states) of quantum optical fields as inputs to general quantum Markov systems. The filters will be quantum harmonic oscillators damped by the input fields, and we exploit the fact that the cascaded filter and system will have a Lindbladian that is naturally Wick-ordered in the filter modes. In particular the initialization of the modulating filter will determine the signal state generated. (orig.)
Fuel cell cathode air filters: Methodologies for design and optimization
Kennedy, Daniel M.; Cahela, Donald R.; Zhu, Wenhua H.; Westrom, Kenneth C.; Nelms, R. Mark; Tatarchuk, Bruce J.
Proton exchange membrane (PEM) fuel cells experience performance degradation, such as reduction in efficiency and life, as a result of poisoning of platinum catalysts by airborne contaminants. Research on these contaminant effects suggests that the best possible solution to allowing fuel cells to operate in contaminated environments is by filtration of the harmful contaminants from the cathode air. A cathode air filter design methodology was created that connects properties of cathode air stream, filter design options, and filter footprint, to a set of adsorptive filter parameters that must be optimized to efficiently operate the fuel cell. Filter optimization requires a study of the trade off between two causal factors of power loss: first, a reduction in power production due to poisoning of the platinum catalyst by chemical contaminants and second, an increase in power requirements to operate the air compressor with a larger pressure drop from additional contaminant filtration. The design methodology was successfully applied to a 1.2 kW fuel cell using a programmable algorithm and predictions were made about the relationships between inlet concentration, breakthrough time, filter design, pressure drop, and compressor power requirements.
Design of Optimal Quincunx Filter Banks for Image Coding
Directory of Open Access Journals (Sweden)
Wu-Sheng Lu
2007-01-01
Full Text Available Two new optimization-based methods are proposed for the design of high-performance quincunx filter banks for the application of image coding. These new techniques are used to build linear-phase finite-length-impulse-response (FIR perfect-reconstruction (PR systems with high coding gain, good frequency selectivity, and certain prescribed vanishing-moment properties. A parametrization of quincunx filter banks based on the lifting framework is employed to structurally impose the PR and linear-phase conditions. Then, the coding gain is maximized subject to a set of constraints on vanishing moments and frequency selectivity. Examples of filter banks designed using the newly proposed methods are presented and shown to be highly effective for image coding. In particular, our new optimal designs are shown to outperform three previously proposed quincunx filter banks in 72% to 95% of our experimental test cases. Moreover, in some limited cases, our optimal designs are even able to outperform the well-known (separable 9/7 filter bank (from the JPEG-2000 standard.
Optimized digital filtering techniques for radiation detection with HPGe detectors
Salathe, M
2015-01-01
This paper describes state-of-the-art digital filtering techniques that are part of the tool kit GEANA which is used as a fast automatic data validation tool for the GERDA experiment. The discussed filters include a novel, nonlinear correction method for ballistic deficits, which is combined with one of three shaping filters: the pseudo-Gaussian, a modified trapezoidal, or a modified cusp filter. The performance of the filters is demonstrated using a 762 g high purity germanium detector that measures gamma-ray lines from radioactive sources in an energy range between 59 and 2615 keV. The modified cusp filter was found to be most optimal for individual gamma-ray lines. Furthermore, it was observed, that even though, the shaping time that minimizes the energy resolution is energy dependent, the loss in resolution by using a constant shaping time over the entire energy range is small, i.e. less than 32 eV for the pseudo-Gaussian filter. This together with good energy resolutions, e.g. 1.59 keV at 1333 keV, this ...
Optimal filtering in multipulse sequences for nuclear quadrupole resonance detection
Osokin, D. Ya.; Khusnutdinov, R. R.; Mozzhukhin, G. V.; Rameev, B. Z.
2014-05-01
The application of the multipulse sequences in nuclear quadrupole resonance (NQR) detection of explosive and narcotic substances has been studied. Various approaches to increase the signal to noise ratio (SNR) of signal detection are considered. We discussed two modifications of the phase-alternated multiple-pulse sequence (PAMS): the 180° pulse sequence with a preparatory pulse and the 90° pulse sequence. The advantages of optimal filtering to detect NQR in the case of the coherent steady-state precession have been analyzed. It has been shown that this technique is effective in filtering high-frequency and low-frequency noise and increasing the reliability of NQR detection. Our analysis also shows the PAMS with 180° pulses is more effective than PSL sequence from point of view of the application of optimal filtering procedure to the steady-state NQR signal.
An Ant Colony Optimization Algorithm for Microwave Corrugated Filters Design
Directory of Open Access Journals (Sweden)
Ivan A. Mantilla-Gaviria
2013-01-01
Full Text Available A practical and useful application of the Ant Colony Optimization (ACO method for microwave corrugated filter design is shown. The classical, general purpose ACO method is adapted to deal with the microwave filter design problem. The design strategy used in this paper is an iterative procedure based on the use of an optimization method along with an electromagnetic simulator. The designs of high-pass and band-pass microwave rectangular waveguide filters working in the C-band and X-band, respectively, for communication applications, are shown. The average convergence performance of the ACO method is characterized by means of Monte Carlo simulations and compared with that obtained with the well-known Genetic Algorithm (GA. The overall performance, for the simulations presented herein, of the ACO is found to be better than that of the GA.
Gravitation search algorithm: Application to the optimal IIR filter design
Directory of Open Access Journals (Sweden)
Suman Kumar Saha
2014-01-01
Full Text Available This paper presents a global heuristic search optimization technique known as Gravitation Search Algorithm (GSA for the design of 8th order Infinite Impulse Response (IIR, low pass (LP, high pass (HP, band pass (BP and band stop (BS filters considering various non-linear characteristics of the filter design problems. This paper also adopts a novel fitness function in order to improve the stop band attenuation to a great extent. In GSA, law of gravity and mass interactions among different particles are adopted for handling the non-linear IIR filter design optimization problem. In this optimization technique, searcher agents are the collection of masses and interactions among them are governed by the Newtonian gravity and the laws of motion. The performances of the GSA based IIR filter designs have proven to be superior as compared to those obtained by real coded genetic algorithm (RGA and standard Particle Swarm Optimization (PSO. Extensive simulation results affirm that the proposed approach using GSA outperforms over its counterparts not only in terms of quality output, i.e., sharpness at cut-off, smaller pass band ripple, higher stop band attenuation, but also the fastest convergence speed with assured stability.
New hybrid genetic particle swarm optimization algorithm to design multi-zone binary filter.
Lin, Jie; Zhao, Hongyang; Ma, Yuan; Tan, Jiubin; Jin, Peng
2016-05-16
The binary phase filters have been used to achieve an optical needle with small lateral size. Designing a binary phase filter is still a scientific challenge in such fields. In this paper, a hybrid genetic particle swarm optimization (HGPSO) algorithm is proposed to design the binary phase filter. The HGPSO algorithm includes self-adaptive parameters, recombination and mutation operations that originated from the genetic algorithm. Based on the benchmark test, the HGPSO algorithm has achieved global optimization and fast convergence. In an easy-to-perform optimizing procedure, the iteration number of HGPSO is decreased to about a quarter of the original particle swarm optimization process. A multi-zone binary phase filter is designed by using the HGPSO. The long depth of focus and high resolution are achieved simultaneously, where the depth of focus and focal spot transverse size are 6.05λ and 0.41λ, respectively. Therefore, the proposed HGPSO can be applied to the optimization of filter with multiple parameters.
OPTIMAL WAVELET FILTER DESIGN FOR REMOTE SENSING IMAGE COMPRESSION
Institute of Scientific and Technical Information of China (English)
Yang Guoan; Zheng Nanning; Guo Shugang
2007-01-01
A new approach for designing the Biorthogonal Wavelet Filter Bank (BWFB) for the purpose of image compression is presented in this letter. The approach is decomposed into two steps.First, an optimal filter bank is designed in theoretical sense based on Vaidyanathan's coding gain criterion in SubBand Coding (SBC) system. Then the above filter bank is optimized based on the criterion of Peak Signal-to-Noise Ratio (PSNR) in JPEG2000 image compression system, resulting in a BWFB in practical application sense. With the approach, a series of BWFB for a specific class of applications related to image compression, such as remote sensing images, can be fast designed. Here,new 5/3 BWFB and 9/7 BWFB are presented based on the above approach for the remote sensing image compression applications. Experiments show that the two filter banks are equally performed with respect to CDF 9/7 and LT 5/3 filter in JPEG2000 standard; at the same time, the coefficients and the lifting parameters of the lifting scheme are all rational, which bring the computational advantage, and the ease for VLSI implementation.
Optimization of Dynamic Range of Cascade Filter Realization
Directory of Open Access Journals (Sweden)
J. Hospodka
2006-09-01
Full Text Available This paper deals with a dynamic range optimization procedure for active filters based on the cascade realization. Dynamic characteristics of the cascade filter depend on many factors, mainly on pole-zero pairing, section ordering and gain assignment. Just the procedure for an optimal gain assignment for particular biquadratic sections is discussed in this paper. The input parameters of the procedure are parameters of particular biquads i.e. pole frequency ÃÂ‰0, quality factor Q, eventually zero frequency ÃÂ‰n for elliptic section and the transfer function type of the section. The gain is distributed so that output signal limitation of particular biquads occurs for the same level of the filter input signal. The procedure is versatile - can be used for analog as well as for digital filters with the cascade structure. The presented algorithm is fully universal (does not suppose any simplification. It has been used in Syntfil package for the filter design in the mathematical program Maple.
Optimized Paraunitary Filter Banks for Time-Frequency Channel Diagonalization
Directory of Open Access Journals (Sweden)
Ju Ziyang
2010-01-01
Full Text Available We adopt the concept of channel diagonalization to time-frequency signal expansions obtained by DFT filter banks. As a generalization of the frequency domain channel representation used by conventional orthogonal frequency-division multiplexing receivers, the time-frequency domain channel diagonalization can be applied to time-variant channels and aperiodic signals. An inherent error in the case of doubly dispersive channels can be limited by choosing adequate windows underlying the filter banks. We derive a formula for the mean-squared sample error in the case of wide-sense stationary uncorrelated scattering (WSSUS channels, which serves as objective function in the window optimization. Furthermore, an enhanced scheme for the parameterization of tight Gabor frames enables us to constrain the window in order to define paraunitary filter banks. We show that the design of windows optimized for WSSUS channels with known statistical properties can be formulated as a convex optimization problem. The performance of the resulting windows is investigated under different channel conditions, for different oversampling factors, and compared against the performance of alternative windows. Finally, a generic matched filter receiver incorporating the proposed channel diagonalization is discussed which may be essential for future reconfigurable radio systems.
Optimized Paraunitary Filter Banks for Time-Frequency Channel Diagonalization
Ju, Ziyang; Hunziker, Thomas; Dahlhaus, Dirk
2010-12-01
We adopt the concept of channel diagonalization to time-frequency signal expansions obtained by DFT filter banks. As a generalization of the frequency domain channel representation used by conventional orthogonal frequency-division multiplexing receivers, the time-frequency domain channel diagonalization can be applied to time-variant channels and aperiodic signals. An inherent error in the case of doubly dispersive channels can be limited by choosing adequate windows underlying the filter banks. We derive a formula for the mean-squared sample error in the case of wide-sense stationary uncorrelated scattering (WSSUS) channels, which serves as objective function in the window optimization. Furthermore, an enhanced scheme for the parameterization of tight Gabor frames enables us to constrain the window in order to define paraunitary filter banks. We show that the design of windows optimized for WSSUS channels with known statistical properties can be formulated as a convex optimization problem. The performance of the resulting windows is investigated under different channel conditions, for different oversampling factors, and compared against the performance of alternative windows. Finally, a generic matched filter receiver incorporating the proposed channel diagonalization is discussed which may be essential for future reconfigurable radio systems.
Directory of Open Access Journals (Sweden)
Samuel Boudet
2014-01-01
Full Text Available Muscle artifacts constitute one of the major problems in electroencephalogram (EEG examinations, particularly for the diagnosis of epilepsy, where pathological rhythms occur within the same frequency bands as those of artifacts. This paper proposes to use the method dual adaptive filtering by optimal projection (DAFOP to automatically remove artifacts while preserving true cerebral signals. DAFOP is a two-step method. The first step consists in applying the common spatial pattern (CSP method to two frequency windows to identify the slowest components which will be considered as cerebral sources. The two frequency windows are defined by optimizing convolutional filters. The second step consists in using a regression method to reconstruct the signal independently within various frequency windows. This method was evaluated by two neurologists on a selection of 114 pages with muscle artifacts, from 20 clinical recordings of awake and sleeping adults, subject to pathological signals and epileptic seizures. A blind comparison was then conducted with the canonical correlation analysis (CCA method and conventional low-pass filtering at 30 Hz. The filtering rate was 84.3% for muscle artifacts with a 6.4% reduction of cerebral signals even for the fastest waves. DAFOP was found to be significantly more efficient than CCA and 30 Hz filters. The DAFOP method is fast and automatic and can be easily used in clinical EEG recordings.
Optimization of well field management
DEFF Research Database (Denmark)
Hansen, Annette Kirstine
Groundwater is a limited but important resource for fresh water supply. Differ- ent conflicting objectives are important when operating a well field. This study investigates how the management of a well field can be improved with respect to different objectives simultaneously. A framework...... objectives. The sequential scheduling optimizes the management stepwise for daily time steps, and allows the final management to vary in time. The research shows that this method performs better than the constant scheduling when large variations in the hydrological conditions occur. This novel approach can...... multi-objective optimization framework has shown to be useful in optimizing the management of well fields, and it has successfully been applied to the two case studies, Hardhof and Søndersø waterworks. If the method is applied to all Danish waterworks it is estimated that 20-32 GWh/year could be saved...
Optimal noise filtering in the chemotactic response of Escherichia coli.
Directory of Open Access Journals (Sweden)
Burton W Andrews
2006-11-01
Full Text Available Information-carrying signals in the real world are often obscured by noise. A challenge for any system is to filter the signal from the corrupting noise. This task is particularly acute for the signal transduction network that mediates bacterial chemotaxis, because the signals are subtle, the noise arising from stochastic fluctuations is substantial, and the system is effectively acting as a differentiator which amplifies noise. Here, we investigated the filtering properties of this biological system. Through simulation, we first show that the cutoff frequency has a dramatic effect on the chemotactic efficiency of the cell. Then, using a mathematical model to describe the signal, noise, and system, we formulated and solved an optimal filtering problem to determine the cutoff frequency that bests separates the low-frequency signal from the high-frequency noise. There was good agreement between the theory, simulations, and published experimental data. Finally, we propose that an elegant implementation of the optimal filter in combination with a differentiator can be achieved via an integral control system. This paper furnishes a simple quantitative framework for interpreting many of the key notions about bacterial chemotaxis, and, more generally, it highlights the constraints on biological systems imposed by noise.
Bifurcations of optimal vector fields
Kiseleva, T.; Wagener, F.
2015-01-01
We study the structure of the solution set of a class of infinite-horizon dynamic programming problems with one-dimensional state spaces, as well as their bifurcations, as problem parameters are varied. The solutions are represented as the integral curves of a multivalued optimal vector field on sta
Mandal, J K
2012-01-01
In this paper a novel approach for de noising images corrupted by random valued impulses has been proposed. Noise suppression is done in two steps. The detection of noisy pixels is done using all neighbor directional weighted pixels (ANDWP) in the 5 x 5 window. The filtering scheme is based on minimum variance of the four directional pixels. In this approach, relatively recent category of stochastic global optimization technique i.e., particle swarm optimization (PSO) has also been used for searching the parameters of detection and filtering operators required for optimal performance. Results obtained shows better de noising and preservation of fine details for highly corrupted images.
Directory of Open Access Journals (Sweden)
I. Sharma
2016-09-01
Full Text Available In this paper, a linear phase FIR filter is designed through recently proposed nature inspired optimization algorithm known as Cuckoo search (CS. A comparative study of Cuckoo search (CS, particle swarm optimization (PSO and artificial bee colony (ABC nature inspired optimization methods in the field of linear phase FIR filter design is also presented. For this purpose, an improved L1 weighted error function is formulated in frequency domain, and minimized through CS, PSO and ABC respectively. The error or objective function has a controlling parameter wt which controls the amount of ripple in the desired band of frequency. The performance of FIR filter is examined through three key parameters; Maximum Pass Band Ripple (MPR, Maximum Stopband Ripple (MSR and Stopband Attenuation (As. Comparative study and the simulation results reveal that the designed filter with CS gives better performance in terms of Maximum Stopband Ripple (MSR, and Stopband Attenuation (As for low order filter design, and for higher order it also gives better performance in term of Maximum Passband Ripple (MPR. Superiority of the proposed technique is also shown through comparison with other recently proposed methods.
An Adaptive Filtering Algorithm using Mean Field Annealing Techniques
Persson, Per; Nordebo, Sven; Claesson, Ingvar
2002-01-01
We present a new approach to discrete adaptive filtering based on the mean field annealing algorithm. The main idea is to find the discrete filter vector that minimizes the matrix form of the Wiener-Hopf equations in a least-squares sense by a generalized mean field annealing algorithm. It is indicated by simulations that this approach, with complexity O(M^2) where M is the filter length, finds a solution comparable to the one obtained by the recursive least squares (RLS) algorithm but withou...
The optimal filtering of a class of dynamic multiscale systems
Institute of Scientific and Technical Information of China (English)
PAN Quan; ZHANG Lei; CUI Peiling; ZHANG Hongcai
2004-01-01
This paper discusses the optimal filtering of a class of dynamic multiscale systems (DMS), which are observed independently by several sensors distributed at different resolution spaces. The system is subject to known dynamic system model. The resolution and sampling frequencies of the sensors are supposed to decrease by a factor of two. By using the Haar wavelet transform to link the state nodes at each of the scales within a time block, a discrete-time model of this class of multiscale systems is given, and the conditions for applying Kalman filtering are proven. Based on the linear time-invariant system, the controllability and observability of the system and the stability of the Kalman filtering is studied, and a theorem is given. It is proved that the Kalman filter is stable if only the system is controllable and observable at the finest scale. Finally, a constant-velocity process is used to obtain insight into the efficiencies offered by our model and algorithm.
OPTIMAL TARGET TRAJECTORY ESTIMATION AND FILTERING USING NETWORKED SENSORS
Institute of Scientific and Technical Information of China (English)
Jiangping HU; Xiaoming HU
2008-01-01
Target tracking using distributed sensor network is in general a challenging problem because it always needs to deal with real-time processing of noisy information. In this paper the problem of using nonlinear sensors such as distance and direction sensors for estimating a moving target is studied.The problem is formulated as a prudent design of nonlinear filters for a linear system subject to noisy nonlinear measurements and partially unknown input, which is generated by an exogenous system.In the worst case where the input is completely unknown, the exogenous dynamics is reduced to the random walk model. It can be shown that the nonlinear filter will have optimal convergence if the number of the sensors are large enough and the convergence rate will be highly improved if the sensors are deployed appropriately. This actually raises an interesting issue on active sensing: how to optimally move the sensors if they are considered as mobile multi-agent systems? Finally, a simulation example is given to illustrate and validate the construction of our filter.
Improved Rao-Blackwellized Particle Filter by Particle Swarm Optimization
Directory of Open Access Journals (Sweden)
Zeng-Shun Zhao
2013-01-01
Full Text Available The Rao-Blackwellized particle filter (RBPF algorithm usually has better performance than the traditional particle filter (PF by utilizing conditional dependency relationships between parts of the state variables to estimate. By doing so, RBPF could not only improve the estimation precision but also reduce the overall computational complexity. However, the computational burden is still too high for many real-time applications. To improve the efficiency of RBPF, the particle swarm optimization (PSO is applied to drive all the particles to the regions where their likelihoods are high in the nonlinear area. So only a small number of particles are needed to participate in the required computation. The experimental results demonstrate that this novel algorithm is more efficient than the standard RBPF.
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
Design of optimal binary phase and amplitude filters for maximization of correlation peak sharpness
Downie, John D.
1991-01-01
Current binary-phase filters used for optical correlation are usually assumed to have uniform amplitude transmission. Here, a new type of filter is studied, the binary-phase-and-amplitude filter. If binary phase values of 0 and pi are assumed, the amplitude transmittance values of this type of filter can be optimized to maximize the peak sharpness. For a polarization-encoded binary-phase filter this can be translated into optimization of the rotation angle of the output polarizer following the filter-spatial-light modulator. An analytic expression is presented for the optimum polarizer angle and thus for the optimum binary-phase-and-amplitude filter design.
Optimal subband Kalman filter for normal and oesophageal speech enhancement.
Ishaq, Rizwan; García Zapirain, Begoña
2014-01-01
This paper presents the single channel speech enhancement system using subband Kalman filtering by estimating optimal Autoregressive (AR) coefficients and variance for speech and noise, using Weighted Linear Prediction (WLP) and Noise Weighting Function (NWF). The system is applied for normal and Oesophageal speech signals. The method is evaluated by Perceptual Evaluation of Speech Quality (PESQ) score and Signal to Noise Ratio (SNR) improvement for normal speech and Harmonic to Noise Ratio (HNR) for Oesophageal Speech (OES). Compared with previous systems, the normal speech indicates 30% increase in PESQ score, 4 dB SNR improvement and OES shows 3 dB HNR improvement.
Stochastic simulation and robust design optimization of integrated photonic filters
Directory of Open Access Journals (Sweden)
Weng Tsui-Wei
2017-01-01
Full Text Available Manufacturing variations are becoming an unavoidable issue in modern fabrication processes; therefore, it is crucial to be able to include stochastic uncertainties in the design phase. In this paper, integrated photonic coupled ring resonator filters are considered as an example of significant interest. The sparsity structure in photonic circuits is exploited to construct a sparse combined generalized polynomial chaos model, which is then used to analyze related statistics and perform robust design optimization. Simulation results show that the optimized circuits are more robust to fabrication process variations and achieve a reduction of 11%–35% in the mean square errors of the 3 dB bandwidth compared to unoptimized nominal designs.
Local Optimality of User Choices and Collaborative Competitive Filtering
Yang, Shuang Hong
2010-01-01
We describe a novel framework for learning recommender models for recommendation systems, which views user-system-item interactions as an opportunity give-and-take process, and encodes both "collaboration" and "competition" mechanisms underlying the interaction. The proposed framework leverages the latent factor models of collaborative filtering to encode "collaboration" (via factor sharing); and in the meanwhile, it utilizes a type of objectives that implies local optimality of user choices to encode "competition". Specifically, it takes into account both the revenue and the opportunity cost of each user decision; and, by optimizing a new objective that are analogous to the economic profit, it encourages that every opportunity being taken by a user be locally the best among the opportunities being offered to him/her. Such competition among candidates opportunities imposes stronger supervision and in turn leads to better generalization to unseen interactions. Empirical results indicates that the collaborative...
Energy Technology Data Exchange (ETDEWEB)
Hwang, Yong Hwa; Lee, Hyung Kwon; Chun, Young Bum; Park, Dae Gyu; Ahn, Sang Bok; Chu, Yong Sun; Kim, Eun Ka
1997-12-01
The development of high efficiency filter was started to protect human beings from the contamination of radioactive particles, toxic gases and bacillus, and its gradual performance increment led to the fabrication of Ultra Low Penetration Air Filter (ULPA) today. The application field of ULPA has been spread not only to the air conditioning of nuclear power facilities, semiconductor industries, life science, optics, medical care and general facilities but also to the core of ultra-precision facilities. Periodic performance test on the filters is essential to extend its life-time through effective maintenance. Especially, the bank test on HEPA filter of nuclear facilities handling radioactive materials is required for environmental safety. Nowadays, the bank test technology has been reached to the utilization of a minimized portable detecting instruments and the evaluation techniques can provide high confidence in the area of particle distribution and leakage test efficiency. (author). 16 refs., 13 tabs., 14 figs.
An optimal nonorthogonal separation of the anisotropic Gaussian convolution filter.
Lampert, Christoph H; Wirjadi, Oliver
2006-11-01
We give an analytical and geometrical treatment of what it means to separate a Gaussian kernel along arbitrary axes in R(n), and we present a separation scheme that allows us to efficiently implement anisotropic Gaussian convolution filters for data of arbitrary dimensionality. Based on our previous analysis we show that this scheme is optimal with regard to the number of memory accesses and interpolation operations needed. The proposed method relies on nonorthogonal convolution axes and works completely in image space. Thus, it avoids the need for a fast Fourier transform (FFT)-subroutine. Depending on the accuracy and speed requirements, different interpolation schemes and methods to implement the one-dimensional Gaussian (finite impulse response and infinite impulse response) can be integrated. Special emphasis is put on analyzing the performance and accuracy of the new method. In particular, we show that without any special optimization of the source code, it can perform anisotropic Gaussian filtering faster than methods relying on the FFT.
Lubineau, Gilles
2009-05-16
The post-processing of experiments with nonuniform fields is still a challenge: the information is often much richer, but its interpretation for identification purposes is not straightforward. However, this is a very promising field of development because it would pave the way for the robust identification of multiple material parameters using only a small number of experiments. This paper presents a goal-oriented filtering technique in which data are combined into new output fields which are strongly correlated with specific quantities of interest (the material parameters to be identified). Thus, this combination, which is nonuniform in space, constitutes a filter of the experimental outputs, whose relevance is quantified by a quality function based on global variance analysis. Then, this filter is optimized using genetic algorithms. © 2009 Springer-Verlag.
Optimized Multichannel Filter Bank with Flat Frequency Response for Texture Segmentation
Kachouie, Nezamoddin N.; Alirezaie, Javad
2005-12-01
Previous approaches to texture analysis and segmentation use multichannel filtering by applying a set of filters in the frequency domain or a set of masks in the spatial domain. This paper presents two new texture segmentation algorithms based on multichannel filtering in conjunction with neural networks for feature extraction and segmentation. The features extracted by Gabor filters have been applied for image segmentation and analysis. Suitable choices of filter parameters and filter bank coverage in the frequency domain to optimize the filters are discussed. Here we introduce two methods to optimize Gabor filter bank. First, a Gabor filter bank with a flat response is implemented and the optimal feature dimension is extracted by competitive networks. Second, a subset of Gabor filter bank is selected to compose the best discriminative filters, so that each filter in this small set can discriminate a pair of textures in a given image. In both approaches, multilayer perceptrons are employed to segment the extracted features. The comparisons of segmentation results generated using the proposed methods and previous research using Gabor, discrete cosine transform (DCT), and Laws filters are presented. Finally, the segmentation results generated by applying the optimized filter banks to textured images are presented and discussed.
Optimized Multichannel Filter Bank with Flat Frequency Response for Texture Segmentation
Directory of Open Access Journals (Sweden)
Kachouie Nezamoddin N
2005-01-01
Full Text Available Previous approaches to texture analysis and segmentation use multichannel filtering by applying a set of filters in the frequency domain or a set of masks in the spatial domain. This paper presents two new texture segmentation algorithms based on multichannel filtering in conjunction with neural networks for feature extraction and segmentation. The features extracted by Gabor filters have been applied for image segmentation and analysis. Suitable choices of filter parameters and filter bank coverage in the frequency domain to optimize the filters are discussed. Here we introduce two methods to optimize Gabor filter bank. First, a Gabor filter bank with a flat response is implemented and the optimal feature dimension is extracted by competitive networks. Second, a subset of Gabor filter bank is selected to compose the best discriminative filters, so that each filter in this small set can discriminate a pair of textures in a given image. In both approaches, multilayer perceptrons are employed to segment the extracted features. The comparisons of segmentation results generated using the proposed methods and previous research using Gabor, discrete cosine transform (DCT, and Laws filters are presented. Finally, the segmentation results generated by applying the optimized filter banks to textured images are presented and discussed.
Intelligent Optimize Design of LCL Filter for Three-Phase Voltage-Source PWM Rectifier
DEFF Research Database (Denmark)
Sun, Wei; Chen, Zhe; Wu, Xiaojie
2009-01-01
Compared to traditional L filter, a LCL filter is more effective on reducing harmonic distortion at switch frequency. So it is important to choose the LCL filter parameters to achieve good filtering effect. This paper introduces some traditional design methods. Design of a LCL filter by genetic...... algorithm (GA) and particle swam optimization (PSO) are presented in this paper and comparison of the two intelligent optimization. Simulation result and calculate data are provided to prove that intelligent optimization are more effective and simple than traditional methods....
Shakhmuratov, R N
2016-01-01
The resonant filtering method transforming frequency modulated radiation field into a train of short pulses is proposed to apply in optical domain. Effective frequency modulation can be achieved by electro-optic modulator or by resonant frequency modulation of the filter with a narrow absorption line. Due to frequency modulation narrow-spectrum CW radiation field is seen by the resonant filter as a comb of equidistant spectral components separated by the modulation frequency. Tuning narrow-bandwidth filter in resonance with $n$-th spectral component of the comb transforms the radiation field into bunches of pulses with $n$ pulses in each bunch. The transformation is explained by the interference of the coherently scattered resonant component of the field with the whole comb. Constructive interference results in formation of pulses, while destructive interference is seen as dark windows between pulses. It is found that the optimal thickness of the resonant filter is several orders of magnitude smaller than the...
Far-field Diffraction Properties of Annular Walsh Filters
Directory of Open Access Journals (Sweden)
Pubali Mukherjee
2013-01-01
Full Text Available Annular Walsh filters are derived from the rotationally symmetric annular Walsh functions which form a complete set of orthogonal functions that take on values either +1 or −1 over the domain specified by the inner and outer radii of the annulus. The value of any annular Walsh function is taken as zero from the centre of the circular aperture to the inner radius of the annulus. The three values 0, +1, and −1 in an annular Walsh function can be realized in a corresponding annular Walsh filter by using transmission values of zero amplitude (i.e., an obscuration, unity amplitude and zero phase, and unity amplitude and phase, respectively. Not only the order of the Walsh filter but also the size of the inner radius of the annulus provides an additional degree of freedom in tailoring of point spread function by using these filters for pupil plane filtering in imaging systems. In this report, we present the far-field amplitude characteristics of some of these filters to underscore their potential for effective use in several demanding applications like high-resolution microscopy, optical data storage, microlithography, optical encryption, and optical micromanipulation.
Robust Pitch Estimation Using an Optimal Filter on Frequency Estimates
DEFF Research Database (Denmark)
Karimian-Azari, Sam; Jensen, Jesper Rindom; Christensen, Mads Græsbøll
2014-01-01
In many scenarios, a periodic signal of interest is often contaminated by different types of noise that may render many existing pitch estimation methods suboptimal, e.g., due to an incorrect white Gaussian noise assumption. In this paper, a method is established to estimate the pitch...... against different noise situations. The simulation results confirm that the proposed MVDR method outperforms the state-of-the-art weighted least squares (WLS) pitch estimator in colored noise and has robust pitch estimates against missing harmonics in some time-frames....... of such signals from unconstrained frequency estimates (UFEs). A minimum variance distortionless response (MVDR) method is proposed as an optimal solution to minimize the variance of UFEs considering the constraint of integer harmonics. The MVDR filter is designed based on noise statistics making it robust...
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.
Directory of Open Access Journals (Sweden)
Jan eKneissler
2015-04-01
Full Text Available Predictive coding appears to be one of the fundamental working principles of brain processing. Amongst other aspects, brains often predict the sensory consequences of their own actions. Predictive coding resembles Kalman filtering, where incoming sensory information is filtered to produce prediction errors for subsequent adaptation and learning. However, to generate prediction errors given motor commands, a suitable temporal forward model is required to generate predictions. While in engineering applications, it is usually assumed that this forward model is known, the brain has to learn it. When filtering sensory input and learning from the residual signal in parallel, a fundamental problem arises: the system can enter a delusional loop when filtering the sensory information using an overly trusted forward model. In this case, learning stalls before accurate convergence because uncertainty about the forward model is not properly accommodated. We present a Bayes-optimal solution to this generic and pernicious problem for the case of linear forward models, which we call Predictive Inference and Adaptive Filtering (PIAF. PIAF filters incoming sensory information and learns the forward model simultaneously. We show that PIAF is formally related to Kalman filtering and to the Recursive Least Squares linear approximation method, but combines these procedures in a Bayes optimal fashion. Numerical evaluations confirm that the delusional loop is precluded and that the learning of the forward model is more than ten-times faster when compared to a naive combination of Kalman filtering and Recursive Least Squares.
Optimal reconstruction of natural images by small sets of Gabor filters
Van Deemter, JH; Cristobal, G
1998-01-01
Images can be reconstructed after being filtered by a Gaussian and a few Gabor filters. Several search methods for the filter parameters for a (near) optimal reconstruction are examined. At first, the search is performed on a 1-D signal which satisfies the radial spectrum of the average of natural i
Mathematical Modeling of Flow Field in Ceramic Candle Filter
Institute of Scientific and Technical Information of China (English)
TaewonSeo; Joo－HongChoi; 等
1998-01-01
Integrated gasification combined cycle(IGCC)is one of the candidates to achieve stringent environmental regulation among the clean coal technologies.Advancing the technology of the hot gas cleanup systems is the most critical component in the development of the IGCC.Thus the aim of this study is to understand the flow field in the ceramic filter and the influence of ceramic filter in removal of the particles contained in the hot gas flow.The numerical model based on the Reynolds stress turbulence model with the Darycy's law in the porous region is adopted.It is found that the effect of the porosity in the flowfield is negligibly small while the effect of the filter length is significant.It is also found as the permeability decreases,the reattachment point due to the flow separation moves upstream,This is because the fluid is sucked into the filter region due to the pressure drop before the flow separation occurs.The particle follows well with the fluid stream and the particle is directly sucked into the filter due to the pressure drop even in the flow separation region.
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...
Directory of Open Access Journals (Sweden)
Khanagha Ali
2010-01-01
Full Text Available Blind identification of MIMO FIR systems has widely received attentions in various fields of wireless data communications. Here, we use Particle Swarm Optimization (PSO as the update mechanism of the well-known inverse filtering approach and we show its good performance compared to original method. Specially, the proposed method is shown to be more robust against lower SNR scenarios or in cases with smaller lengths of available data records. Also, a modified version of PSO is presented which further improves the robustness and preciseness of PSO algorithm. However the most important promise of the modified version is its drastically faster convergence compared to standard implementation of PSO.
DEFF Research Database (Denmark)
Misaridis, Thanasis; Jensen, Jørgen Arendt
1999-01-01
performed with the program Field II. A commercial scanner (B-K Medical 3535) was modified and interfaced to an arbitrary function generator along with an RF power amplifier (Ritec). Hydrophone measurements in water were done to establish excitation voltage and corresponding intensity levels (I-sptp and I......This paper presents a coded excitation imaging system based on a predistorted FM excitation and a digital compression filter designed for medical ultrasonic applications, in order to preserve both axial resolution and contrast. In radars, optimal Chebyshev windows efficiently weight a nearly...
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...
Multiple constant multiplication optimizations for field programmable gate arrays
Kumm, Martin
2016-01-01
This work covers field programmable gate array (FPGA)-specific optimizations of circuits computing the multiplication of a variable by several constants, commonly denoted as multiple constant multiplication (MCM). These optimizations focus on low resource usage but high performance. They comprise the use of fast carry-chains in adder-based constant multiplications including ternary (3-input) adders as well as the integration of look-up table-based constant multipliers and embedded multipliers to get the optimal mapping to modern FPGAs. The proposed methods can be used for the efficient implementation of digital filters, discrete transforms and many other circuits in the domain of digital signal processing, communication and image processing. Contents Heuristic and ILP-Based Optimal Solutions for the Pipelined Multiple Constant Multiplication Problem Methods to Integrate Embedded Multipliers, LUT-Based Constant Multipliers and Ternary (3-Input) Adders An Optimized Multiple Constant Multiplication Architecture ...
Chen, Jing; Liu, Tundong; Jiang, Hao
2016-01-01
A Pareto-based multi-objective optimization approach is proposed to design multichannel FBG filters. Instead of defining a single optimal objective, the proposed method establishes the multi-objective model by taking two design objectives into account, which are minimizing the maximum index modulation and minimizing the mean dispersion error. To address this optimization problem, we develop a two-stage evolutionary computation approach integrating an elitist non-dominated sorting genetic algorithm (NSGA-II) and technique for order preference by similarity to ideal solution (TOPSIS). NSGA-II is utilized to search for the candidate solutions in terms of both objectives. The obtained results are provided as Pareto front. Subsequently, the best compromise solution is determined by the TOPSIS method from the Pareto front according to the decision maker's preference. The design results show that the proposed approach yields a remarkable reduction of the maximum index modulation and the performance of dispersion spectra of the designed filter can be optimized simultaneously.
Courtney, Joseph M; Rienstra, Chad M
2016-08-01
We present a systematic study of dipolar double quantum (DQ) filtering in (13)C-labeled organic solids over a range of magic-angle spinning rates, using the SPC-n recoupling sequence element with a range of n symmetry values from 3 to 11. We find that efficient recoupling can be achieved for values n⩾7, provided that the (13)C nutation frequency is on the order of 100kHz or greater. The decoupling-field dependence was investigated and explicit heteronuclear decoupling interference conditions identified. The major determinant of DQ filtering efficiency is the decoupling interference between (13)C and (1)H fields. For (13)C nutation frequencies greater than 75kHz, optimal performance is observed without an applied (1)H field. At spinning rates exceeding 20kHz, symmetry conditions as low as n=3 were found to perform adequately.
Optimal adaptive normalized matched filter for large antenna arrays
Kammoun, Abla
2016-09-13
This paper focuses on the problem of detecting a target in the presence of a compound Gaussian clutter with unknown statistics. To this end, we focus on the design of the adaptive normalized matched filter (ANMF) detector which uses the regularized Tyler estimator (RTE) built from N-dimensional observations x, · · ·, x in order to estimate the clutter covariance matrix. The choice for the RTE is motivated by its possessing two major attributes: first its resilience to the presence of outliers, and second its regularization parameter that makes it more suitable to handle the scarcity in observations. In order to facilitate the design of the ANMF detector, we consider the regime in which n and N are both large. This allows us to derive closed-form expressions for the asymptotic false alarm and detection probabilities. Based on these expressions, we propose an asymptotically optimal setting for the regularization parameter of the RTE that maximizes the asymptotic detection probability while keeping the asymptotic false alarm probability below a certain threshold. Numerical results are provided in order to illustrate the gain of the proposed detector over a recently proposed setting of the regularization parameter.
The Optimization of a Microfluidic CTC Filtering Chip by Simulation
Directory of Open Access Journals (Sweden)
Huan Li
2017-03-01
Full Text Available The detection and separation of circulating tumor cells (CTCs are crucial in early cancer diagnosis and cancer prognosis. Filtration through a thin film is one of the size and deformability based separation methods, which can isolate rare CTCs from the peripheral blood of cancer patients regardless of their heterogeneity. In this paper, volume of fluid (VOF multiphase flow models are employed to clarify the cells’ filtering processes. The cells may deform significantly when they enter a channel constriction, which will induce cell membrane stress and damage if the area strain is larger than the critical value. Therefore, the cellular damage criterion characterized by membrane area strain is presented in our model, i.e., the lysis limit of the lipid bilayer is taken as the critical area strain. Under this criterion, we discover that the microfilters with slit-shaped pores do less damage to cells than those with circular pores. The influence of contact angle between the microfilters and blood cells on cellular injury is also discussed. Moreover, the optimal film thickness and flux in our simulations are obtained as 0.5 μm and 0.375 mm/s, respectively. These findings will provide constructive guidance for the improvement of next generation microfilters with higher throughput and less cellular damage.
A Low Cost Structurally Optimized Design for Diverse Filter Types
Kazmi, Majida; Aziz, Arshad; AKHTAR, Pervez; Ikram, Nassar
2016-01-01
A wide range of image processing applications deploys two dimensional (2D)-filters for performing diversified tasks such as image enhancement, edge detection, noise suppression, multi scale decomposition and compression etc. All of these tasks require multiple type of 2D-filters simultaneously to acquire the desired results. The resource hungry conventional approach is not a viable option for implementing these computationally intensive 2D-filters especially in a resource constraint environme...
Singh, R.; Verma, H. K.
2013-12-01
This paper presents a teaching-learning-based optimization (TLBO) algorithm to solve parameter identification problems in the designing of digital infinite impulse response (IIR) filter. TLBO based filter modelling is applied to calculate the parameters of unknown plant in simulations. Unlike other heuristic search algorithms, TLBO algorithm is an algorithm-specific parameter-less algorithm. In this paper big bang-big crunch (BB-BC) optimization and PSO algorithms are also applied to filter design for comparison. Unknown filter parameters are considered as a vector to be optimized by these algorithms. MATLAB programming is used for implementation of proposed algorithms. Experimental results show that the TLBO is more accurate to estimate the filter parameters than the BB-BC optimization algorithm and has faster convergence rate when compared to PSO algorithm. TLBO is used where accuracy is more essential than the convergence speed.
Institute of Scientific and Technical Information of China (English)
Li Shu; Zhuo Jiashou; Ren Qingwen
2000-01-01
In this paper, an optimal criterion is presented for adaptive Kalman filter in a control sys tem with unknown variances of stochastic vibration by constructing a function of noise variances and minimizing the function. We solve the model and measure variances by using DFP optimal method to guarantee the results of Kalman filter to be optimized. Finally, the control of vibration can be implemented by LQG method.
Optimization of offshore natural gas field development
Johansen, Gaute Rannem
2011-01-01
In this thesis the target is to find the optimal development solution of an offshore natural gas field. Natural gas is increasing in importance as an energy source. Whilst most of the large oil fields have been developed, there are still several major natural gas deposits that may be developed. In addition, there are also smaller offshore natural gas fields that may be put into production. Finding an optimal development solution for these resources will increase the availability of natural ga...
Behavioral model for common mode filter and performance optimization aspects
Roc'h, A.; Bergsma, H.; Bergsma, J.G.; Leferink, Frank Bernardus Johannes
2008-01-01
A well designed common mode filter for motor drive application can significantly improve the level of electromagnetic interference generated by the cable and the motor housing. The subsequent design of this filter is strongly dependent on the actual in situ parameters of the motor drive and often
Optease vena cava filter optimal indwelling time and retrievability.
Rimon, Uri; Bensaid, Paul; Golan, Gil; Garniek, Alexander; Khaitovich, Boris; Dotan, Zohar; Konen, Eli
2011-06-01
The purpose of this study was to assess the indwelling time and retrievability of the Optease IVC filter. Between 2002 and 2009, a total of 811 Optease filters were inserted: 382 for prophylaxis in multitrauma patients and 429 for patients with venous thromboembolic (VTE) disease. In 139 patients [97 men and 42 women; mean age, 36 (range, 17-82) years], filter retrieval was attempted. They were divided into two groups to compare change in retrieval policy during the years: group A, 60 patients with filter retrievals performed before December 31 2006; and group B, 79 patients with filter retrievals from January 2007 to October 2009. A total of 128 filters were successfully removed (57 in group A, and 71 in group B). The mean filter indwelling time in the study group was 25 (range, 3-122) days. In group A the mean indwelling time was 18 (range, 7-55) days and in group B 31 days (range, 8-122). There were 11 retrieval failures: 4 for inability to engage the filter hook and 7 for inability to sheathe the filter due to intimal overgrowth. The mean indwelling time of group A retrieval failures was 16 (range, 15-18) days and in group B 54 (range, 17-122) days. Mean fluoroscopy time for successful retrieval was 3.5 (range, 1-16.6) min and for retrieval failures 25.2 (range, 7.2-62) min. Attempts to retrieve the Optease filter can be performed up to 60 days, but more failures will be encountered with this approach.
Optimization of the reconstruction and anti-aliasing filter in a Wiener filter system
Wesselink, J.M.; Berkhoff, A.P.
2006-01-01
This paper discusses the influence of the reconstruction and anti-aliasing filters on the performance of a digital implementation of a Wiener filter for active noise control. The overall impact will be studied in combination with a multi-rate system approach. A reconstruction and anti-aliasing filte
DEFF Research Database (Denmark)
Lee, Carson Odell; Wagner, Florian Benedikt; Boe-Hansen, Rasmus
Nitrification is an important biological process commonly used in biological drinking water filters to remove ammonium from drinking water. Recent research has shown that a lack of micronutrients could be limiting the performance of these filters. Because nitrification is a biological process, ca...... to be an important diagnostic tool that could decrease regulatory hurdles, and save time and money....
Optimization of the reconstruction and anti-aliasing filter in a wiener filter system
Wesselink, J.M.; Berkhoff, A.P.
2006-01-01
This paper discusses the influence of the reconstruction and anti-aliasing filters on the performance of a digital implementation of a Wiener filter for active noise control. The overall impact will be studied in combination with a multi-rate system approach. A reconstruction and anti-aliasing filte
Daugman, J G
1985-07-01
Two-dimensional spatial linear filters are constrained by general uncertainty relations that limit their attainable information resolution for orientation, spatial frequency, and two-dimensional (2D) spatial position. The theoretical lower limit for the joint entropy, or uncertainty, of these variables is achieved by an optimal 2D filter family whose spatial weighting functions are generated by exponentiated bivariate second-order polynomials with complex coefficients, the elliptic generalization of the one-dimensional elementary functions proposed in Gabor's famous theory of communication [J. Inst. Electr. Eng. 93, 429 (1946)]. The set includes filters with various orientation bandwidths, spatial-frequency bandwidths, and spatial dimensions, favoring the extraction of various kinds of information from an image. Each such filter occupies an irreducible quantal volume (corresponding to an independent datum) in a four-dimensional information hyperspace whose axes are interpretable as 2D visual space, orientation, and spatial frequency, and thus such a filter set could subserve an optimally efficient sampling of these variables. Evidence is presented that the 2D receptive-field profiles of simple cells in mammalian visual cortex are well described by members of this optimal 2D filter family, and thus such visual neurons could be said to optimize the general uncertainty relations for joint 2D-spatial-2D-spectral information resolution. The variety of their receptive-field dimensions and orientation and spatial-frequency bandwidths, and the correlations among these, reveal several underlying constraints, particularly in width/length aspect ratio and principal axis organization, suggesting a polar division of labor in occupying the quantal volumes of information hyperspace.(ABSTRACT TRUNCATED AT 250 WORDS)
Optimized digital filtering techniques for radiation detection with HPGe detectors
Salathe, Marco; Kihm, Thomas
2016-02-01
This paper describes state-of-the-art digital filtering techniques that are part of GEANA, an automatic data analysis software used for the GERDA experiment. The discussed filters include a novel, nonlinear correction method for ballistic deficits, which is combined with one of three shaping filters: a pseudo-Gaussian, a modified trapezoidal, or a modified cusp filter. The performance of the filters is demonstrated with a 762 g Broad Energy Germanium (BEGe) detector, produced by Canberra, that measures γ-ray lines from radioactive sources in an energy range between 59.5 and 2614.5 keV. At 1332.5 keV, together with the ballistic deficit correction method, all filters produce a comparable energy resolution of ~1.61 keV FWHM. This value is superior to those measured by the manufacturer and those found in publications with detectors of a similar design and mass. At 59.5 keV, the modified cusp filter without a ballistic deficit correction produced the best result, with an energy resolution of 0.46 keV. It is observed that the loss in resolution by using a constant shaping time over the entire energy range is small when using the ballistic deficit correction method.
Joint Conditional Random Field Filter for Multi-Object Tracking
Directory of Open Access Journals (Sweden)
Luo Ronghua
2011-03-01
Full Text Available Object tracking can improve the performance of mobile robot especially in populated dynamic environments. A novel joint conditional random field Filter (JCRFF based on conditional random field with hierarchical structure is proposed for multi-object tracking by abstracting the data associations between objects and measurements to be a sequence of labels. Since the conditional random field makes no assumptions about the dependency structure between the observations and it allows non-local dependencies between the state and the observations, the proposed method can not only fuse multiple cues including shape information and motion information to improve the stability of tracking, but also integrate moving object detection and object tracking quite well. At the same time, implementation of multi-object tracking based on JCRFF with measurements from the laser range finder on a mobile robot is studied. Experimental results with the mobile robot developed in our lab show that the proposed method has higher precision and better stability than joint probabilities data association filter (JPDAF.
Telescope Multi-Field Wavefront Control with a Kalman Filter
Lou, John Z.; Redding, David; Sigrist, Norbert; Basinger, Scott
2008-01-01
An effective multi-field wavefront control (WFC) approach is demonstrated for an actuated, segmented space telescope using wavefront measurements at the exit pupil, and the optical and computational implications of this approach are discussed. The integration of a Kalman Filter as an optical state estimator into the wavefront control process to further improve the robustness of the optical alignment of the telescope will also be discussed. Through a comparison of WFC performances between on-orbit and ground-test optical system configurations, the connection (and a possible disconnection) between WFC and optical system alignment under these circumstances are analyzed. Our MACOS-based computer simulation results will be presented and discussed.
Topology optimization of pulse shaping filters using the Hilbert transform envelope extraction
DEFF Research Database (Denmark)
Lazarov, Boyan Stefanov; Matzen, René; Elesin, Yuriy
2011-01-01
Time domain topology optimization is applied to design pulse shaping filters. The objective function depends on the pulse envelope, which is extracted by utilizing the Hilbert transform. The gradients with respect to the topology optimization variables are derived, and the optimization methodology...
Stochastic Optimal Estimation with Fuzzy Random Variables and Fuzzy Kalman Filtering
Institute of Scientific and Technical Information of China (English)
FENG Yu-hu
2005-01-01
By constructing a mean-square performance index in the case of fuzzy random variable, the optimal estimation theorem for unknown fuzzy state using the fuzzy observation data are given. The state and output of linear discrete-time dynamic fuzzy system with Gaussian noise are Gaussian fuzzy random variable sequences. An approach to fuzzy Kalman filtering is discussed. Fuzzy Kalman filtering contains two parts: a real-valued non-random recurrence equation and the standard Kalman filtering.
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 ...
Optimal Filter Estimation for Lucas-Kanade Optical Flow
Directory of Open Access Journals (Sweden)
Remus Brad
2012-09-01
Full Text Available Optical flow algorithms offer a way to estimate motion from a sequence of images. The computation of optical flow plays a key-role in several computer vision applications, including motion detection and segmentation, frame interpolation, three-dimensional scene reconstruction, robot navigation and video compression. In the case of gradient based optical flow implementation, the pre-filtering step plays a vital role, not only for accurate computation of optical flow, but also for the improvement of performance. Generally, in optical flow computation, filtering is used at the initial level on original input images and afterwards, the images are resized. In this paper, we propose an image filtering approach as a pre-processing step for the Lucas-Kanade pyramidal optical flow algorithm. Based on a study of different types of filtering methods and applied on the Iterative Refined Lucas-Kanade, we have concluded on the best filtering practice. As the Gaussian smoothing filter was selected, an empirical approach for the Gaussian variance estimation was introduced. Tested on the Middlebury image sequences, a correlation between the image intensity value and the standard deviation value of the Gaussian function was established. Finally, we have found that our selection method offers a better performance for the Lucas-Kanade optical flow algorithm.
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Temporal filters and spatial filters are widely used in many areas of signal processing. A number of optimal design criteria to these problems are available in the literature. Various computational techniques are also presented to optimize these criteria chosen. There are many drawbacks in these methods. In this paper, we introduce a unified framework for optimal design of temporal and spatial filters. Most of the optimal design problems of FIR filters and beamformers are included in the framework. It is shown that all the design problems can be reformulated as convex optimization form as the second-order cone programming (SOCP) and solved efficiently via the well-established interior point methods. The main advantage of our SOCP approach as compared with earlier approaches is that it can include most of the existing methods as its special cases, which leads to more flexible designs. Furthermore, the SOCP approach can optimize multiple required performance measures, which is the drawback of earlier approaches. The SOCP approach is also developed to optimally design temporal and spatial two-dimensional filter and spatial matrix filter. Numerical results demonstrate the effectiveness of the proposed approach.
Towards Optimal Filtering on ARM for ATLAS Tile Calorimeter Front-End Processing
Cox, Mitchell A.
2015-10-01
The Large Hadron Collider at CERN generates enormous amounts of raw data which presents a serious computing challenge. After planned upgrades in 2022, the data output from the ATLAS Tile Calorimeter will increase by 200 times to over 40 Tb/s. Advanced and characteristically expensive Digital Signal Processors (DSPs) and Field Programmable Gate Arrays (FPGAs) are currently used to process this quantity of data. It is proposed that a cost- effective, high data throughput Processing Unit (PU) can be developed by using several ARM System on Chips in a cluster configuration to allow aggregated processing performance and data throughput while maintaining minimal software design difficulty for the end-user. ARM is a cost effective and energy efficient alternative CPU architecture to the long established x86 architecture. This PU could be used for a variety of high-level algorithms on the high data throughput raw data. An Optimal Filtering algorithm has been implemented in C++ and several ARM platforms have been tested. Optimal Filtering is currently used in the ATLAS Tile Calorimeter front-end for basic energy reconstruction and is currently implemented on DSPs.
Optimal design and performance verification of a broadband waveguide filter using ANN-GA algorithm
Directory of Open Access Journals (Sweden)
Manidipa Nath
2013-09-01
Full Text Available In this work design and optimization of EBGstructure having multiple dielectric posts uniformly placed insidea rectangular waveguide is done to extract filter responses.Frequency response of BPF configuration using trained ANNmodel of multipost rectangular waveguide are studied andoptimized using GA. The geometrical and positional dimensionof post parameters are varied in accordance to the requirementof reflectance and transmittance of the filter.
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 ...
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.
A robust approach to optimal matched filter design in ultrasonic non-destructive evaluation (NDE)
Li, Minghui; Hayward, Gordon
2017-02-01
The matched filter was demonstrated to be a powerful yet efficient technique to enhance defect detection and imaging in ultrasonic non-destructive evaluation (NDE) of coarse grain materials, provided that the filter was properly designed and optimized. In the literature, in order to accurately approximate the defect echoes, the design utilized the real excitation signals, which made it time consuming and less straightforward to implement in practice. In this paper, we present a more robust and flexible approach to optimal matched filter design using the simulated excitation signals, and the control parameters are chosen and optimized based on the real scenario of array transducer, transmitter-receiver system response, and the test sample, as a result, the filter response is optimized and depends on the material characteristics. Experiments on industrial samples are conducted and the results confirm the great benefits of the method.
Field performance assessment and optimization
Energy Technology Data Exchange (ETDEWEB)
Alba, Juan Carlos [Ziff Energy Group (Canada)
2011-07-01
Ziff Energy Group is a company with a presence in over 60 countries, where it operates in the oil and gas industry, particularly the heavy oil sector. The aim of this presentation is to show the benefits of benchmarking in the heavy oil industry. Heavy oil is defined as oil with a gravity between 10 and 20 API and a viscosity of 100 to 10,000 cp; resources are distributed through all the continents. Benchmarking consists in analyzing performance, looking for new ways to improve it, and implementing those new methods; benchmarking thus promotes measurement and improvement within a company. However, benchmarking in the heavy oil sector presents challenges, due to the difference of the oil play properties, the different cultures inherent in each company, and the abundance of data. This presentation demonstrated that, despite the challenges, benchmarking is a useful tool for optimizing heavy oil operations.
Optimization of H sup - output in a magnetically filtered multicusp source
Energy Technology Data Exchange (ETDEWEB)
Hosoda, Masayuki; Tanebe, Tomoaki; Naitou, Hirosi; Fukumasa, Osamu (Yamaguchi Univ. (Japan))
1991-10-01
On optimization of the volume production type H{sup -} ion source, the effects of both the magnetic filter position and the plasma grid bias voltage for H{sup -} output have been investigated experimentally. It is found that the H{sup -} output can be enhanced by optimizing the magnetic filter position, or the bias voltage of plasma grid. It is also confirmed that these phenomena correlate strongly with the variations of plasma parameters in the extraction region. (author).
Design Optimization of Diesel Particulate Filter Using CFD
Directory of Open Access Journals (Sweden)
Mr. Y. Rajasekhar Reddy
2015-12-01
Full Text Available The diesel particulate filter (DPF is a device designed to remove diesel particulate matter or soot from the exhaust gas of a diesel engine. A series of tests have been performed on a downscaled DPF prototype. This prototype had high filtration efficiency. Then the next step is to study the soot and ash handling capacity of DPF system and perform tests on a full-scale prototype. In order to move forward to the next step the functionality of the filter should be investigated. Moreover, a complete model of flow inside the filter can help parameter investigation on both downscale and full-scale prototype. Building up a CFD model using fluent which is capable to simulate the flow through all channels and porous media of the filter plates and tuning the pressure drop parameters for all steps of filtration from clean filter to dirty one are the main achievements of this project. CFD results have been tuned by using experimental data of filtration tests.
Design of one-dimensional optical pulse-shaping filters by time-domain topology optimization
DEFF Research Database (Denmark)
Yang, Lirong; Lavrinenko, Andrei; Hvam, Jørn Märcher
2009-01-01
Time-domain topology optimization is used here to design optical pulse-shaping filters in Si/SiO2 thin-film systems. A novel envelope objective function as well as explicit penalization are used to adapt the optimization method to this unique class of design problems.......Time-domain topology optimization is used here to design optical pulse-shaping filters in Si/SiO2 thin-film systems. A novel envelope objective function as well as explicit penalization are used to adapt the optimization method to this unique class of design problems....
Energy Technology Data Exchange (ETDEWEB)
Leach, R.R.; Schultz, C.; Dowla, F.
1997-07-15
Development of a worldwide network to monitor seismic activity requires deployment of seismic sensors in areas which have not been well studied or may have from available recordings. Development and testing of detection and discrimination algorithms requires a robust representative set of calibrated seismic events for a given region. Utilizing events with poor signal-to-noise (SNR) can add significant numbers to usable data sets, but these events must first be adequately filtered. Source and path effects can make this a difficult task as filtering demands are highly varied as a function of distance, event magnitude, bearing, depth etc. For a given region, conventional methods of filter selection can be quite subjective and may require intensive analysis of many events. In addition, filter parameters are often overly generalized or contain complicated switching. We have developed a method to provide an optimized filter for any regional or teleseismically recorded event. Recorded seismic signals contain arrival energy which is localized in frequency and time. Localized temporal signals whose frequency content is different from the frequency content of the pre-arrival record are identified using rms power measurements. The method is based on the decomposition of a time series into a set of time series signals or scales. Each scale represents a time-frequency band with a constant Q. SNR is calculated for a pre-event noise window and for a window estimated to contain the arrival. Scales with high SNR are used to indicate the band pass limits for the optimized filter.The results offer a significant improvement in SNR particularly for low SNR events. Our method provides a straightforward, optimized filter which can be immediately applied to unknown regions as knowledge of the geophysical characteristics is not required. The filtered signals can be used to map the seismic frequency response of a region and may provide improvements in travel-time picking, bearing estimation
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.
Filters in topology optimization based on Helmholtz‐type differential equations
DEFF Research Database (Denmark)
Lazarov, Boyan Stefanov; Sigmund, Ole
2011-01-01
The aim of this paper is to apply a Helmholtz‐type partial differential equation as an alternative to standard density filtering in topology optimization problems. Previously, this approach has been successfully applied as a sensitivity filter. The usual filtering techniques in topology optimizat......The aim of this paper is to apply a Helmholtz‐type partial differential equation as an alternative to standard density filtering in topology optimization problems. Previously, this approach has been successfully applied as a sensitivity filter. The usual filtering techniques in topology...... optimization require information about the neighbor cells, which is difficult to obtain for fine meshes or complex domains and geometries. The complexity of the problem increases further in parallel computing, when the design domain is decomposed into multiple non‐overlapping partitions. Obtaining information...... from the neighbor subdomains is an expensive operation. The proposed filter technique requires only mesh information necessary for the finite element discretization of the problem. The main idea is to define the filtered variable implicitly as a solution of a Helmholtz‐type differential equation...
Big Bang–Big Crunch Optimization Algorithm for Linear Phase Fir Digital Filter Design
Directory of Open Access Journals (Sweden)
Ms. Rashmi Singh Dr. H. K. Verma
2012-02-01
Full Text Available The Big Bang–Big Crunch (BB–BC optimization algorithm is a new optimization method that relies on the Big Bang and Big Crunch theory, one of the theories of the evolution of the universe. In this paper, a Big Bang–Big Crunch algorithm has been used here for the design of linear phase finite impulse response (FIR filters. Here the experimented fitness function based on the mean squared error between the actual and the ideal filter response. This paper presents the plot of magnitude response of FIR filters and error graph. The BB-BC seems to be promising tool for FIR filter design especially in a dynamic environment where filter coefficients have to be adapted and fast convergence is of importance.
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.
Optimization of multiplexed holographic gratings in PQ-PMMA for spectral-spatial imaging filters.
Luo, Yuan; Gelsinger, Paul J; Barton, Jennifer K; Barbastathis, George; Kostuk, Raymond K
2008-03-15
Holographic gratings formed in thick phenanthrenquinone- (PQ-) doped poly(methyl methacrylate) (PMMA) can be made to have narrowband spectral and spatial transmittance filtering properties. We present the design and performance of angle-multiplexed holographic filters formed in PQ-PMMA at 488 nm and reconstructed with a LED operated at approximately 630 nm. The dark delay time between exposure and the preillumination exposure of the polymer prior to exposure of the holographic area are varied to optimize the diffraction efficiency of multiplexed holographic filters. The resultant holographic filters can enhance the performance of four-dimensional spatial-spectral imaging systems. The optimized filters are used to simultaneously sample spatial and spectral information at five different depths separated by 50 microm within biological tissue samples.
Noise Reduction with Optimal Variable Span Linear Filters
DEFF Research Database (Denmark)
Jensen, Jesper Rindom; Benesty, Jacob; Christensen, Mads Græsbøll
2016-01-01
of eigenvectors stemming from a joint diagonalization of the covariance matrices of the signal of interest and the noise. The resulting filters are flexible in that it is possible to trade off distortion of the desired signal for improved noise reduction. This tradeoff is controlled by the number of eigenvectors...
Abe, Tomomi; Hashimoto, Shuji; Matsumoto, Mitsuharu
2010-02-01
epsilon-filter can reduce most kinds of noise from a single-channel noisy signal while preserving signals that vary drastically such as speech signals. It can reduce not only stationary noise but also nonstationary noise. However, it has some parameters whose values are set empirically. So far, there have been few studies to evaluate the appropriateness of the parameter settings for epsilon-filter. This paper employs the correlation coefficient of the filter output and the difference between the filter input and output as the evaluation function of the parameter setting. This paper also describes the algorithm to set the optimal parameter value of epsilon-filter automatically. To evaluate the adequateness of the obtained parameter, the mean absolute error is calculated. The experimental results show that the adequate parameter in epsilon-filter can be obtained automatically by using the proposed method.
Mahmudin, D.; Estu, T. T.; Fathnan, A. A.; Maulana, Y. Y.; Daud, P.; Sugandhi, G.; Wijayanto, Y. N.
2016-11-01
Optical filter is very important components in WDM network. MRR is a basic structure to design the optical filter because of easy to design for improving its performance. This paper discusses an innovative structure of the MRR, which is Triple Coupler Ring Resonators (TCRR) for optical filter applications. Values of width between bus and ring and values of radius of the ring in the structure TCRR were analyzed and optimized for several variations for obtaining coupling coefficient values. Therefore, wide Free Spectral Range (FSR) and high crosstalk suppression bandwidth can be obtained. As results, at the optimized width of gap of 100 nm and the optimized radiation of 8 μm, FSR of 2.85 THz and crosstalk suppression bandwidth of 60 GHz were achieved. Based on the results, this structure can be used for filtering optical signals in optical fiber communication.
Preliminary field evaluation of high efficiency steel filters
Energy Technology Data Exchange (ETDEWEB)
Bergman, W.; Larsen, G.; Lopez, R. [Lawrence Livermore National Laboratory, CA (United States)] [and others
1995-02-01
We have conducted an evaluation of two high efficiency steel filters in the exhaust of an uranium oxide grit blaster at the Y-12 Plant in Oak Ridge Tennessee. The filters were installed in a specially designed filter housing with a reverse air-pulse cleaning system for automatically cleaning the filters in-place. Previous tests conducted on the same filters and housing at LLNL under controlled conditions using Arizona road dust showed good cleanability with reverse air pulses. Two high efficiency steel filters, containing 64 pleated cartridge elements housed in the standard 2` x 2` x 1` HEPA frame, were evaluated in the filter test housing using a 1,000 cfm slip stream containing a high concentration of depleted uranium oxide dust. One filter had the pleated cartridges manufactured to our specifications by the Pall Corporation and the other by Memtec Corporation. Test results showed both filters had a rapid increase in pressure drop with time, and reverse air pulses could not decrease the pressure drop. We suspected moisture accumulation in the filters was the problem since there were heavy rains during the evaluations, and the pressure drop of the Memtec filter decreased dramatically after passing clean, dry air through the filter and after the filter sat idle for one week. Subsequent laboratory tests on a single filter cartridge confirmed that water accumulation in the filter was responsible for the increase in filter pressure drop and the inability to lower the pressure drop by reverse air pulses. No effort was made to identify the source of the water accumulation and correct the problem because the available funds were exhausted.
An Optimal Unramified Tower of Function Fields
DEFF Research Database (Denmark)
Efficient construction of long AG--codes resulting from optimal towers of function fields is known to be difficult. In the following a tower which is both optimal and unramified, that is a tower in which all places are unramified after some level, is investigated in the hope that its simple ramif...... ramification structure can be exploited in the construction of AG--codes. Results are mostly negative, but helps clarifying the difficulties in computing bases of Riemann--Roch spaces....
An Optimal Unramified Tower of Function Fields
DEFF Research Database (Denmark)
Brander, Kristian
2008-01-01
Efficient construction of long algebraic geometric--codes resulting from optimal towers of function fields is known to be difficult. In the following a tower which is both optimal and unramified after its third level, is investigated in the hope that its simple ramification structure can be explo...... be exploited in the construction of algebraic geometric--codes. Results are mostly negative, but help clarifying the difficulties in computing bases of Riemann--Roch spaces....
The Optimization of a Microfluidic CTC Filtering Chip by Simulation
Huan Li; Jianfeng Chen; Wenqiang Du; Youjun Xia; Depei Wang; Gang Zhao; Jiaru Chu
2017-01-01
The detection and separation of circulating tumor cells (CTCs) are crucial in early cancer diagnosis and cancer prognosis. Filtration through a thin film is one of the size and deformability based separation methods, which can isolate rare CTCs from the peripheral blood of cancer patients regardless of their heterogeneity. In this paper, volume of fluid (VOF) multiphase flow models are employed to clarify the cells’ filtering processes. The cells may deform significantly when they enter a cha...
Tap-length optimization of adaptive filters used in stereophonic acoustic echo cancellation
DEFF Research Database (Denmark)
Kar, Asutosh; Swamy, M.N.S.
2017-01-01
of acoustic echo paths. The tap-length optimization is applied to a single long adaptive filter with thousands of coefficients to decrease the total number of weights, which in turn reduces the computational load. To further increase the convergence rate, the proposed tap-length-optimization algorithm...
Waffenschmidt, Siw; Hermanns, Tatjana; Gerber-Grote, Andreas; Mostardt, Sarah
2017-02-01
To determine a suitable approach to a systematic search for epidemiologic publications in bibliographic databases. For this purpose, suitable sensitive, precise, and optimized filters were to be selected for MEDLINE searches. In addition, the relevance of bibliographic databases was determined. Epidemiologic systematic reviews (SRs) retrieved in a systematic search and company dossiers were screened to identify epidemiologic publications (primary studies and SRs) published since 2007. These publications were used to generate a test and validation set. Furthermore, each SR's search strategy was reviewed, and epidemiologic filters were extracted. The search syntaxes were validated using the relative recall method. The test set comprises 729 relevant epidemiologic publications, of which 566 were MEDLINE-indexed. About 27 epidemiologic filters were extracted. One suitable sensitive filter was identified (Larney et al. 2013: 95.94% sensitivity). Precision was presumably underestimated so that no precise or optimized filters can be recommended. About 77.64% of the publications were found in MEDLINE. There is currently no suitable approach to conducting efficient systematic searches for epidemiologic publications in bibliographic databases. The filter by Larney et al. (2013) can be used for sensitive MEDLINE searches. No robust conclusions can be drawn on precise or optimized filters. Additional search approaches should be considered. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.
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...
Energy Technology Data Exchange (ETDEWEB)
Sun, Winston Y. [Univ. of California, Berkeley, CA (United States)
1993-04-01
This thesis solves the problem of finding the optimal linear noise-reduction filter for linear tomographic image reconstruction. The optimization is data dependent and results in minimizing the mean-square error of the reconstructed image. The error is defined as the difference between the result and the best possible reconstruction. Applications for the optimal filter include reconstructions of positron emission tomographic (PET), X-ray computed tomographic, single-photon emission tomographic, and nuclear magnetic resonance imaging. Using high resolution PET as an example, the optimal filter is derived and presented for the convolution backprojection, Moore-Penrose pseudoinverse, and the natural-pixel basis set reconstruction methods. Simulations and experimental results are presented for the convolution backprojection method.
Two-Dimensional IIR Filter Design Using Simulated Annealing Based Particle Swarm Optimization
Directory of Open Access Journals (Sweden)
Supriya Dhabal
2014-01-01
Full Text Available We present a novel hybrid algorithm based on particle swarm optimization (PSO and simulated annealing (SA for the design of two-dimensional recursive digital filters. The proposed method, known as SA-PSO, integrates the global search ability of PSO with the local search ability of SA and offsets the weakness of each other. The acceptance criterion of Metropolis is included in the basic algorithm of PSO to increase the swarm’s diversity by accepting sometimes weaker solutions also. The experimental results reveal that the performance of the optimal filter designed by the proposed SA-PSO method is improved. Further, the convergence behavior as well as optimization accuracy of proposed method has been improved significantly and computational time is also reduced. In addition, the proposed SA-PSO method also produces the best optimal solution with lower mean and variance which indicates that the algorithm can be used more efficiently in realizing two-dimensional digital filters.
Optimal Tuner Selection for Kalman-Filter-Based Aircraft Engine Performance Estimation
Simon, Donald L.; Garg, Sanjay
2011-01-01
An emerging approach in the field of aircraft engine controls and system health management is the inclusion of real-time, onboard models for the inflight estimation of engine performance variations. This technology, typically based on Kalman-filter concepts, enables the estimation of unmeasured engine performance parameters that can be directly utilized by controls, prognostics, and health-management applications. A challenge that complicates this practice is the fact that an aircraft engine s performance is affected by its level of degradation, generally described in terms of unmeasurable health parameters such as efficiencies and flow capacities related to each major engine module. Through Kalman-filter-based estimation techniques, the level of engine performance degradation can be estimated, given that there are at least as many sensors as health parameters to be estimated. However, in an aircraft engine, the number of sensors available is typically less than the number of health parameters, presenting an under-determined estimation problem. A common approach to address this shortcoming is to estimate a subset of the health parameters, referred to as model tuning parameters. The problem/objective is to optimally select the model tuning parameters to minimize Kalman-filterbased estimation error. A tuner selection technique has been developed that specifically addresses the under-determined estimation problem, where there are more unknown parameters than available sensor measurements. A systematic approach is applied to produce a model tuning parameter vector of appropriate dimension to enable estimation by a Kalman filter, while minimizing the estimation error in the parameters of interest. Tuning parameter selection is performed using a multi-variable iterative search routine that seeks to minimize the theoretical mean-squared estimation error of the Kalman filter. This approach can significantly reduce the error in onboard aircraft engine parameter estimation
Hemispherical-field-of-view, nonimaging narrow-band spectral filter
Miles, R. B.; Webb, S. G.; Griffith, E. L.
1981-01-01
Two compound parabolic concentrators are used to create a 180-deg-field-of-view spectral filter. The collection optics are reflective and are designed to collimate the light through a multilayer interference filter and then to refocus it onto an optical detector. Assuming unit reflectance and no loss through the optical filter, this device operates at the thermodynamic collection limit.
Observations of vector magnetic fields with a magneto-optic filter
Cacciani, Alessandro; Varsik, John; Zirin, Harold
1990-01-01
The use of the magnetooptic filter to observe solar magnetic fields in the potassium line at 7699 A is described. The filter has been used in the Big Bear videomagnetograph since October 23. It gives a high sensitivity and dynamic range for longitudnal magnetic fields and enables measurement of transverse magnetic fields using the sigma component. Examples of the observations are presented.
A new shunt DC active filter of power supply in a steady high magnetic field facility
Institute of Scientific and Technical Information of China (English)
WANG Lei; LIU Xiao-Ning; WANG Can
2011-01-01
A DC active power filter is an indispensable part in a high power and high stability power supply system, especially in the power supply system of the Steady High Magnetic Field Facility, which requires that the current ripple should be limited to 50 parts per million. In view of the disadvantages of the series DC active power filter and shunt Pulse Width Modulation DC active filter, this paper puts forward a novel DC active filter by combining the advantages of the transistor regulator and the shunt type. The structure and principle of the new shunt linear active filter are introduced. Meanwhile, the design of several key components that construct the new shunt linear active filter is also analyzed. The simulation model and an experimental prototype of the shunt linear active filter are developed, and the results verify that the parameter design is reasonable and the shunt active filter has a good filter effect.
Optimization Models for Petroleum Field Exploitation
Energy Technology Data Exchange (ETDEWEB)
Jonsbraaten, Tore Wiig
1998-12-31
This thesis presents and discusses various models for optimal development of a petroleum field. The objective of these optimization models is to maximize, under many uncertain parameters, the project`s expected net present value. First, an overview of petroleum field optimization is given from the point of view of operations research. Reservoir equations for a simple reservoir system are derived and discretized and included in optimization models. Linear programming models for optimizing production decisions are discussed and extended to mixed integer programming models where decisions concerning platform, wells and production strategy are optimized. Then, optimal development decisions under uncertain oil prices are discussed. The uncertain oil price is estimated by a finite set of price scenarios with associated probabilities. The problem is one of stochastic mixed integer programming, and the solution approach is to use a scenario and policy aggregation technique developed by Rockafellar and Wets although this technique was developed for continuous variables. Stochastic optimization problems with focus on problems with decision dependent information discoveries are also discussed. A class of ``manageable`` problems is identified and an implicit enumeration algorithm for finding optimal decision policy is proposed. Problems involving uncertain reservoir properties but with a known initial probability distribution over possible reservoir realizations are discussed. Finally, a section on Nash-equilibrium and bargaining in an oil reservoir management game discusses the pool problem arising when two lease owners have access to the same underlying oil reservoir. Because the oil tends to migrate, both lease owners have incentive to drain oil from the competitors part of the reservoir. The discussion is based on a numerical example. 107 refs., 31 figs., 14 tabs.
Design of Maximally Flat FIR Filters Based on Explicit Formulas Combined with Optimization
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
A maximally flat FIR filter design method based on explicit formulas combined with simulated annealing and random search was presented. Utilizing the explicit formulas to calculate the initial values, the finite-word-length FIR filter design problem was converted into optimization of the filter coefficients. An optimization method combined with local discrete random search and simulated annealing was proposed, with the result of optimum solution in the sense of Chebyshev approximation. The proposed method can simplify the design process of FIR filter and reduce the calculation burden. The simulation result indicates that the proposed method is superior to the traditional round off method and can reduce the value of the objective function to 41%-74%.
Automation of Optimized Gabor Filter Parameter Selection for Road Cracks Detection
Directory of Open Access Journals (Sweden)
Haris Ahmad Khan
2016-03-01
Full Text Available Automated systems for road crack detection are extremely important in road maintenance for vehicle safety and traveler’s comfort. Emerging cracks in roads need to be detected and accordingly repaired as early as possible to avoid further damage thus reducing rehabilitation cost. In this paper, a robust method for Gabor filter parameters optimization for automatic road crack detection is discussed. Gabor filter has been used in previous literature for similar applications. However, there is a need for automatic selection of optimized Gabor filter parameters due to variation in texture of roads and cracks. The problem of change of background, which in fact is road texture, is addressed through a learning process by using synthetic road crack generation for Gabor filter parameter tuning. Tuned parameters are then tested on real cracks and a thorough quantitative analysis is performed for performance evaluation.
AN ITERATIVE ALGORITHM FOR OPTIMAL DESIGN OF NON-FREQUENCY-SELECTIVE FIR DIGITAL FILTERS
Institute of Scientific and Technical Information of China (English)
Duan Miyi; Sun Chunlai; Liu Xin; Tian Xinguang
2008-01-01
This paper proposes a novel iterative algorithm for optimal design of non-frequency-se-lective Finite Impulse Response (FIR) digital filters based on the windowing method. Different from the traditional optimization concept of adjusting the window or the filter order in the windowing design of an FIR digital filter,the key idea of the algorithm is minimizing the approximation error by succes-sively modifying the design result through an iterative procedure under the condition of a fixed window length. In the iterative procedure,the known deviation of the designed frequency response in each iteration from the ideal frequency response is used as a reference for the next iteration. Because the approximation error can be specified variably,the algorithm is applicable for the design of FIR digital filters with different technical requirements in the frequency domain. A design example is employed to illustrate the efficiency of the algorithm.
Institute of Scientific and Technical Information of China (English)
Shuo Zhang,Yan Zhao,Min Li,; Jianhui Zhao
2015-01-01
The global y optimal recursive filtering problem is stu-died for a class of systems with random parameter matrices, stochastic nonlinearities, correlated noises and missing measure-ments. The stochastic nonlinearities are presented in the system model to reflect multiplicative random disturbances, and the addi-tive noises, process noise and measurement noise, are assumed to be one-step autocorrelated as wel as two-step cross-correlated. A series of random variables is introduced as the missing rates governing the intermittent measurement losses caused by un-favorable network conditions. The aim of the addressed filtering problem is to design an optimal recursive filter for the uncertain systems based on an innovation approach such that the filtering error is global y minimized at each sampling time. A numerical simulation example is provided to il ustrate the effectiveness and applicability of the proposed algorithm.
Comparative analysis of zero aliasing logarithmic mapped optimal trade-off correlation filter
Tehsin, Sara; Rehman, Saad; Bilal, Ahmed; Chaudry, Qaiser; Saeed, Omer; Abbas, Muhammad; Young, Rupert
2017-05-01
Correlation filters are a well established means for target recognition tasks. However, the unintentional effect of circular correlation has a negative influence on the performance of correlation filters as they are implemented in frequency domain. The effects of aliasing are minimized by introducing zero aliasing constraints in the template and test image. In this paper, the comparative analysis of logarithmic zero aliasing optimal trade off correlation filters has been carried out for different types of target distortions. The zero aliasing Maximum Average Correlation Height (MACH) filter has been identified as the best choice based on our research for achieving enhanced results in the presence of any type of variance which are discussed in results section. The reformulation of the MACH expressions with zero aliasing has been made to demonstrate the achievable enhancement to the logarithmic MACH filter in target detection applications.
Optimal configurations of filter cavity in future gravitational-wave detectors
Khalili, Farit Ya
2010-01-01
Sensitivity of future laser interferometric gravitational-wave detectors can be improved using squeezed light with frequency-dependent squeeze angle and/or amplitude, which can be created using additional so-called filter cavities. Here we compare performances of several variants of this scheme, proposed during last years, assuming the case of a single relatively short (tens of meters) filter cavity suitable for implementation already during the life cycle of the second generation detectors, like Advanced LIGO. Using numerical optimization, we show that the phase filtering scheme proposed by Kimble et al [Phys.Rev.D 65, 022002 (2001)] looks as the best candidate for this scenario.
Design, optimization and fabrication of an optical mode filter for integrated optics.
Magnin, Vincent; Zegaoui, Malek; Harari, Joseph; François, Marc; Decoster, Didier
2009-04-27
We present the design, optimization, fabrication and characterization of an optical mode filter, which attenuates the snaking behavior of light caused by a lateral misalignment of the input optical fiber relative to an optical circuit. The mode filter is realized as a bottleneck section inserted in an optical waveguide in front of a branching element. It is designed with Bézier curves. Its effect, which depends on the optical state of polarization, is experimentally demonstrated by investigating the equilibrium of an optical splitter, which is greatly improved however only in TM mode. The measured optical losses induced by the filter are 0.28 dB.
Directory of Open Access Journals (Sweden)
R. Caballero-Águila
2013-01-01
and each sensor noise are two-step cross-correlated. Under these assumptions and by an innovation approach, recursive algorithms for the optimal linear filter are derived by using the two basic estimation fusion structures; more specifically, both centralized and distributed fusion estimation algorithms are proposed. The accuracy of these estimators is measured by their error covariance matrices, which allow us to compare their performance in a numerical simulation example that illustrates the feasibility of the proposed filtering algorithms and shows a comparison with other existing filters.
Dynamic Optimization of Feedforward Automatic Gauge Control Based on Extended Kalman Filter
Institute of Scientific and Technical Information of China (English)
YANG Bin-hu; YANG Wei-dong; CHEN Lian-gui; QU Lei
2008-01-01
Automatic gauge control is an essentially nonlinear process varying with time delay, and stochastically varying input and process noise always influence the target gauge control accuracy. To improve the control capability of feedforward automatic gauge control, Kalman filter was employed to filter the noise signal transferred from one stand to another. The linearized matrix that the Kalman filter algorithm needed was concluded; thus, the feedforward automatic gauge control architecture was dynamically optimized. The theoretical analyses and simulation show that the proposed algorithm is reasonable and effective.
Reliability-Oriented Optimization of the LC Filter Design of a Buck DC-DC Converter
DEFF Research Database (Denmark)
Liu, Yi; Huang, Meng; Wang, Huai
2017-01-01
Lifetime is an important performance factor in the reliable operation of power converters. However, the state-of-the-art LC filter design of a buck DC-DC converter is limited to the specifications of voltage and current ripples and constrains in power density and cost without reliability...... considerations. This paper proposes a method to optimize the design of the LC filters from a reliability perspective, besides other considerations. An enhanced model is derived to quantify the lifetime of the capacitor in the filter considering the electro-thermal stress on it. Furthermore, the influence...
Optimal Divergence-Free Hatch Filter for GNSS Single-Frequency Measurement
Directory of Open Access Journals (Sweden)
Byungwoon Park
2017-02-01
Full Text Available The Hatch filter is a code-smoothing technique that uses the variation of the carrier phase. It can effectively reduce the noise of a pseudo-range with a very simple filter construction, but it occasionally causes an ionosphere-induced error for low-lying satellites. Herein, we propose an optimal single-frequency (SF divergence-free Hatch filter that uses a satellite-based augmentation system (SBAS message to reduce the ionospheric divergence and applies the optimal smoothing constant for its smoothing window width. According to the data-processing results, the overall performance of the proposed filter is comparable to that of the dual frequency (DF divergence-free Hatch filter. Moreover, it can reduce the horizontal error of 57 cm to 37 cm and improve the vertical accuracy of the conventional Hatch filter by 25%. Considering that SF receivers dominate the global navigation satellite system (GNSS market and that most of these receivers include the SBAS function, the filter suggested in this paper is of great value in that it can make the differential GPS (DGPS performance of the low-cost SF receivers comparable to that of DF receivers.
Optimal Divergence-Free Hatch Filter for GNSS Single-Frequency Measurement
Park, Byungwoon; Lim, Cheolsoon; Yun, Youngsun; Kim, Euiho; Kee, Changdon
2017-01-01
The Hatch filter is a code-smoothing technique that uses the variation of the carrier phase. It can effectively reduce the noise of a pseudo-range with a very simple filter construction, but it occasionally causes an ionosphere-induced error for low-lying satellites. Herein, we propose an optimal single-frequency (SF) divergence-free Hatch filter that uses a satellite-based augmentation system (SBAS) message to reduce the ionospheric divergence and applies the optimal smoothing constant for its smoothing window width. According to the data-processing results, the overall performance of the proposed filter is comparable to that of the dual frequency (DF) divergence-free Hatch filter. Moreover, it can reduce the horizontal error of 57 cm to 37 cm and improve the vertical accuracy of the conventional Hatch filter by 25%. Considering that SF receivers dominate the global navigation satellite system (GNSS) market and that most of these receivers include the SBAS function, the filter suggested in this paper is of great value in that it can make the differential GPS (DGPS) performance of the low-cost SF receivers comparable to that of DF receivers. PMID:28245584
Optimal Divergence-Free Hatch Filter for GNSS Single-Frequency Measurement.
Park, Byungwoon; Lim, Cheolsoon; Yun, Youngsun; Kim, Euiho; Kee, Changdon
2017-02-24
The Hatch filter is a code-smoothing technique that uses the variation of the carrier phase. It can effectively reduce the noise of a pseudo-range with a very simple filter construction, but it occasionally causes an ionosphere-induced error for low-lying satellites. Herein, we propose an optimal single-frequency (SF) divergence-free Hatch filter that uses a satellite-based augmentation system (SBAS) message to reduce the ionospheric divergence and applies the optimal smoothing constant for its smoothing window width. According to the data-processing results, the overall performance of the proposed filter is comparable to that of the dual frequency (DF) divergence-free Hatch filter. Moreover, it can reduce the horizontal error of 57 cm to 37 cm and improve the vertical accuracy of the conventional Hatch filter by 25%. Considering that SF receivers dominate the global navigation satellite system (GNSS) market and that most of these receivers include the SBAS function, the filter suggested in this paper is of great value in that it can make the differential GPS (DGPS) performance of the low-cost SF receivers comparable to that of DF receivers.
Optimal design study of high order FIR digital filters based on neural network algorithm
Institute of Scientific and Technical Information of China (English)
王小华; 何怡刚
2004-01-01
An optimal design approach of high order FIR digital filter is developed based on the algorithm of neural networks with cosine basis function . The main idea is to minimize the sum of the square errors between the amplitude response of the desired FIR filter and that of the designed by training the weights of neural networks, then obtains the impulse response of FIR digital filter . The convergence theorem of the neural networks algorithm is presented and proved,and the optimal design method is introduced by designing four kinds of FIR digital filters , i.e., low-pass, high-pass,bandpass , and band-stop FIR digital filter. The results of the amplitude responses show that attenuation in stop-bands is more than 60 dB with no ripple and pulse existing in pass-bands, and cutoff frequency of passband and stop-band is easily controlled precisely . The presented optimal design approach of high order FIR digital filter is significantly effective.
Directory of Open Access Journals (Sweden)
Xiang Gao
2012-05-01
Full Text Available In order to process target tracking approximation with unknown motion state models beforehand in a two-dimensional field of binary proximity sensors, the algorithms based on cost functions of particle filters and near-linear curve simple optimization are proposed in this paper. Through moving target across detecting intersecting fields of sensor nodes sequentially, cost functions are introduced to solve target tracking approximation and velocity estimation which is not similar to traditional particle filters that rely on probabilistic assumptions about the motion states. Then a near-linear curve geometric approach is used to simplify and easily describe target trajectories that are below a certain error measure. Because there maybe some sensor nodes invalid in practice, so a fault-tolerant detection is applied to avoid the nodes’ reporting fault and also improve accuracy of tracking at the same time. The validity of our algorithms is demonstrated through simulation results.
FPGA Implementation of Optimal Filtering Algorithm for TileCal ROD System
Torres, J; Castillo, V; Cuenca, C; Ferrer, A; Fullana, E; González, V; Higón, E; Poveda, J; Ruiz-Martinez, A; Salvachúa, B; Sanchis, E; Solans, C; Valero, A; Valls, J A
2008-01-01
Traditionally, Optimal Filtering Algorithm has been implemented using general purpose programmable DSP chips. Alternatively, new FPGAs provide a highly adaptable and flexible system to develop this algorithm. TileCal ROD is a multi-channel system, where similar data arrives at very high sampling rates and is subject to simultaneous tasks. It include different FPGAs with high I/O and with parallel structures that provide a benefit at a data analysis. The Optical Multiplexer Board is one of the elements presents in TileCal ROD System. It has FPGAs devices that present an ideal platform for implementing Optimal Filtering Algorithm. Actually this algorithm is performing in the DSPs included at ROD Motherboard. This work presents an alternative to implement Optimal Filtering Algorithm.
Towards an optimal sampling of peculiar velocity surveys for Wiener Filter reconstructions
Sorce, Jenny G.; Hoffman, Yehuda; Gottlöber, Stefan
2017-06-01
The Wiener Filter (WF) technique enables the reconstruction of density and velocity fields from observed radial peculiar velocities. This paper aims at identifying the optimal design of peculiar velocity surveys within the WF framework. The prime goal is to test the dependence of the reconstruction quality on the distribution and nature of data points. Mock data sets, extending to 250 h-1 Mpc, are drawn from a constrained simulation that mimics the local Universe to produce realistic mock catalogues. Reconstructed fields obtained with these mocks are compared to the reference simulation. Comparisons, including residual distributions, cell-to-cell and bulk velocities, imply that the presence of field data points is essential to properly measure the flows. The fields reconstructed from mocks that consist only of galaxy cluster data points exhibit poor-quality bulk velocities. In addition, the reconstruction quality depends strongly on the grouping of individual data points into single points to suppress virial motions in high-density regions. Conversely, the presence of a Zone of Avoidance hardly affects the reconstruction. For a given number of data points, a uniform sample does not score any better than a sample with decreasing number of data points with the distance. The best reconstructions are obtained with a grouped survey containing field galaxies: assuming no error, they differ from the simulated field by less than 100 km s-1 up to the extreme edge of the catalogues or up to a distance of three times the mean distance of data points for non-uniform catalogues. The overall conclusions hold when errors are added.
Inverse Problem of Air Filtration of Nanoparticles: Optimal Quality Factors of Fibrous Filters
Directory of Open Access Journals (Sweden)
Dahua Shou
2015-01-01
Full Text Available Application of nanofibers has become an emerging approach to enhance filtration efficiency, but questions arise about the decrease in Quality factor (QF for certain particles due to the rapidly increasing pressure drop. In this paper, we theoretically investigate the QF of dual-layer filters for filtration of monodisperse and polydisperse nanoparticles. The inverse problem of air filtration, as defined in this work, consists in determining the optimal construction of the two-layer fibrous filter with the maximum QF. In comparison to a single-layer substrate, improved QF values for dual-layer filters are found when a second layer with proper structural parameters is added. The influences of solidity, fiber diameter, filter thickness, face velocity, and particle size on the optimization of QF are studied. The maximum QF values for realistic polydisperse particles with a lognormal size distribution are also found. Furthermore, we propose a modified QF (MQF accounting for the effects of energy cost and flow velocity, which are significant in certain operations. The optimal MQF of the dual-layer filter is found to be over twice that of the first layer. This work provides a quick tool for designing and optimizing fibrous structures with better performance for the air filtration of specific nanoparticles.
Optimal fractional delay-IIR filter design using cuckoo search algorithm.
Kumar, Manjeet; Rawat, Tarun Kumar
2015-11-01
This paper applied a novel global meta-heuristic optimization algorithm, cuckoo search algorithm (CSA) to determine optimal coefficients of a fractional delay-infinite impulse response (FD-IIR) filter and trying to meet the ideal frequency response characteristics. Since fractional delay-IIR filter design is a multi-modal optimization problem, it cannot be computed efficiently using conventional gradient based optimization techniques. A weighted least square (WLS) based fitness function is used to improve the performance to a great extent. FD-IIR filters of different orders have been designed using the CSA. The simulation results of the proposed CSA based approach have been compared to those of well accepted evolutionary algorithms like Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). The performance of the CSA based FD-IIR filter is superior to those obtained by GA and PSO. The simulation and statistical results affirm that the proposed approach using CSA outperforms GA and PSO, not only in the convergence rate but also in optimal performance of the designed FD-IIR filter (i.e., smaller magnitude error, smaller phase error, higher percentage improvement in magnitude and phase error, fast convergence rate). The absolute magnitude and phase error obtained for the designed 5th order FD-IIR filter are as low as 0.0037 and 0.0046, respectively. The percentage improvement in magnitude error for CSA based 5th order FD-IIR design with respect to GA and PSO are 80.93% and 74.83% respectively, and phase error are 76.04% and 71.25%, respectively.
An Optimal Observing System Study for the Kuroshio Extension using Particle Filters
Kramer, Werner; van Leeuwen, Peter Jan; Pierieni, Stefano; Dijkstra, Henk
2010-05-01
The Kuroshio Extension - the eastward-flowing free jet formed when the warm waters of the Kuroshio separate from the Japanese coast - reveals bimodal behavior. It changes from an elongated, energetic meandering jet into a weaker, unstable jet with a reduced zonal penetration. Many of its characteristics, e.g. the decadal period and the more stable character of the elongated state, are also observed in a reduced-gravity ocean model of the northern Pacific basin with a schematic Japanese coastline driven by a constant double-gyre wind field. The success of this idealized model suggests that intrinsic nonlinear mechanisms play a major role in determining the meander pattern of the mean flow. The low complexity of the model makes it ideal to perform an observing system study. Here, we take a new approach by using particle filters to assimilate observations into the model. An ensemble of model states is integrated over time from an initial distribution. The first approach is to pick one run as the synthetic truth. Observations are produced from this synthetic truth with an additional observation error. The particle filter technique adjusts the weight of each ensemble run - each particle - according to the observation value and the error distribution. From the ensemble and its weight distribution the expectation and probability distribution of the state vector can be computed. As the ensemble itself is not altered by the filter, different sets of observations, e.g. with different geometrical configurations, locations and/or time resolutions, can be analyzed a posteriori. The particle filter analyses allows us to identify which observations have a large impact on reconstructing the true state of Kuroshio Extension. More precisely, which observations contribute to a (local) reduction in the entropy of the ensemble. In a way each observation is then linked to an area of influence, which permits for determining the flow of information. We will present results where
Optimal Filtering Algorithm for Stochastic 2-D FMM Ⅱ with Multiplicative Noise
Institute of Scientific and Technical Information of China (English)
CHU Dongsheng; LIANG Meng; SHI Xin; ZHANG Ling
2004-01-01
A stochastic two-dimensional Fornasini-Marchesini's Model Ⅱ (2-D FMM Ⅱ) with multiplicative noise is given,and a filtering algorithm for this model, which is optimal in the sense of linear minimum-variance, is developed. The stochastic 2-D FMM Ⅱ with multiplicative noise can be reduced to a 1-D model, and the proposed optimal filtering algorithm for the stochastic 2-D FMM Ⅱ with multiplicative noise is obtained by using the state estimation theory of 1-D systems. An example is given to illustrate the validity of this algorithm.
Optimizing Cost of Continuous Overlapping Queries over Data Streams by Filter Adaption
Xie, Qing
2016-01-12
The problem we aim to address is the optimization of cost management for executing multiple continuous queries on data streams, where each query is defined by several filters, each of which monitors certain status of the data stream. Specially the filter can be shared by different queries and expensive to evaluate. The conventional objective for such a problem is to minimize the overall execution cost to solve all queries, by planning the order of filter evaluation in shared strategy. However, in streaming scenario, the characteristics of data items may change in process, which can bring some uncertainty to the outcome of individual filter evaluation, and affect the plan of query execution as well as the overall execution cost. In our work, considering the influence of the uncertain variation of data characteristics, we propose a framework to deal with the dynamic adjustment of filter ordering for query execution on data stream, and focus on the issues of cost management. By incrementally monitoring and analyzing the results of filter evaluation, our proposed approach can be effectively adaptive to the varied stream behavior and adjust the optimal ordering of filter evaluation, so as to optimize the execution cost. In order to achieve satisfactory performance and efficiency, we also discuss the trade-off between the adaptivity of our framework and the overhead incurred by filter adaption. The experimental results on synthetic and two real data sets (traffic and multimedia) show that our framework can effectively reduce and balance the overall query execution cost and keep high adaptivity in streaming scenario.
STUDY OF TOPOLOGY OPTIMIZATION FOR THERMO-STRUCTURAL COUPLING FIELD
Institute of Scientific and Technical Information of China (English)
Zuo Kongtian; Qian Qin; Zhao Yudong; Chen Liping
2005-01-01
A number of critical problems of topology optimization concerning the thermostructural coupling field are studied at length. The governing equations and topology optimization model for the thermal-structural coupling field are derived, with an adjoint method for sensitivity analysis of the thermo-structural coupling field proposed. The optimization algorithm for coupling field topology optimization is investigated and a flowchart of coupling field topology optimization presented. The theory and algorithms are implemented and verified by two numerical examples.
Adaptive Conflict-Free Optimization of Rule Sets for Network Security Packet Filtering Devices
Directory of Open Access Journals (Sweden)
Andrea Baiocchi
2015-01-01
Full Text Available Packet filtering and processing rules management in firewalls and security gateways has become commonplace in increasingly complex networks. On one side there is a need to maintain the logic of high level policies, which requires administrators to implement and update a large amount of filtering rules while keeping them conflict-free, that is, avoiding security inconsistencies. On the other side, traffic adaptive optimization of large rule lists is useful for general purpose computers used as filtering devices, without specific designed hardware, to face growing link speeds and to harden filtering devices against DoS and DDoS attacks. Our work joins the two issues in an innovative way and defines a traffic adaptive algorithm to find conflict-free optimized rule sets, by relying on information gathered with traffic logs. The proposed approach suits current technology architectures and exploits available features, like traffic log databases, to minimize the impact of ACO development on the packet filtering devices. We demonstrate the benefit entailed by the proposed algorithm through measurements on a test bed made up of real-life, commercial packet filtering devices.
Tabus, I; Petrescu, D; Gabbouj, M
1996-01-01
A training framework is developed in this paper to design optimal nonlinear filters for various signal and image processing tasks. The targeted families of nonlinear filters are the Boolean filters and stack filters. The main merit of this framework at the implementation level is perhaps the absence of constraining models, making it nearly universal in terms of application areas. We develop fast procedures to design optimal or close to optimal filters, based on some representative training set. Furthermore, the training framework shows explicitly the essential part of the initial specification and how it affects the resulting optimal solution. Symmetry constraints are imposed on the data and, consequently, on the resulting optimal solutions for improved performance and ease of implementation. The case study is dedicated to natural images. The properties of optimal Boolean and stack filters, when the desired signal in the training set is the image of a natural scene, are analyzed. Specifically, the effect of changing the desired signal (using various natural images) and the characteristics of the noise (the probability distribution function, the mean, and the variance) is analyzed. Elaborate experimental conditions were selected to investigate the robustness of the optimal solutions using a sensitivity measure computed on data sets. A remarkably low sensitivity and, consequently, a good generalization power of Boolean and stack filters are revealed. Boolean-based filters are thus shown to be not only suitable for image restoration but also robust, making it possible to build libraries of "optimal" filters, which are suitable for a set of applications.
Swarm Intelligence for Optimizing Hybridized Smoothing Filter in Image Edge Enhancement
Rao, B. Tirumala; Dehuri, S.; Dileep, M.; Vindhya, A.
In this modern era, image transmission and processing plays a major role. It would be impossible to retrieve information from satellite and medical images without the help of image processing techniques. Edge enhancement is an image processing step that enhances the edge contrast of an image or video in an attempt to improve its acutance. Edges are the representations of the discontinuities of image intensity functions. For processing these discontinuities in an image, a good edge enhancement technique is essential. The proposed work uses a new idea for edge enhancement using hybridized smoothening filters and we introduce a promising technique of obtaining best hybrid filter using swarm algorithms (Artificial Bee Colony (ABC), Particle Swarm Optimization (PSO) and Ant Colony Optimization (ACO)) to search for an optimal sequence of filters from among a set of rather simple, representative image processing filters. This paper deals with the analysis of the swarm intelligence techniques through the combination of hybrid filters generated by these algorithms for image edge enhancement.
Frequency invariant beamforming via optimal array pattern synthesis and FIR filters design
Institute of Scientific and Technical Information of China (English)
YAN Shefeng; MA Yuanliang
2005-01-01
An approach to designing time domain broadband frequency invariant beamformer via optimal array pattern synthesis and optimal FIR filters design is proposed. First, the working frequency band is decomposed into a number of narrow band frequency bins. The array weights at each frequency bin are designed via optimal array pattern synthesis methods to insure that the synthesized pattern approximates the desired one within the mainlobe area.Then, a bank of FIR filters corresponding to the input channels are designed to provide the frequency responses that approximate the array weights in the working frequency band for each sensor. Finally, each sensor feeds a FIR filter and the filter outputs are summed to produce the beam output time series. Both array pattern synthesis and FIR filters design problems are formulated as the second-order cone programming (SOCP), which can be easily solved using well-developed interior-point methods. Results of computer simulations and lake-experiment for a twelve-element semicircular array demonstrate satisfactory performance of the proposed approach.
Lim, Wei Jer; Neoh, Siew Chin; Norizan, Mohd Natashah; Mohamad, Ili Salwani
2015-05-01
Optimization for complex circuit design often requires large amount of manpower and computational resources. In order to optimize circuit performance, it is critical not only for circuit designers to adjust the component value but also to fulfill objectives such as gain, cutoff frequency, ripple and etc. This paper proposes Non-dominated Sorting Genetic Algorithm II (NSGA-II) to optimize a ninth order multiple feedback Chebyshev low pass filter. Multi-objective Pareto-Based optimization is involved whereby the research aims to obtain the best trade-off for minimizing the pass-band ripple, maximizing the output gain and achieving the targeted cut-off frequency. The developed NSGA-II algorithm is executed on the NGSPICE circuit simulator to assess the filter performance. Overall results show satisfactory in the achievements of the required design specifications.
Ding, Ze-Min; Chen, Lin-Gen; Ge, Yan-Lin; Sun, Feng-Rui
2016-04-01
A theoretical model for energy selective electron (ESE) heat pumps operating with two-dimensional electron reservoirs is established in this study. In this model, a double-resonance energy filter operating with a total momentum filtering mechanism is considered for the transmission of electrons. The optimal thermodynamic performance of the ESE heat pump devices is also investigated. Numerical calculations show that the heating load of the device with two resonances is larger, whereas the coefficient of performance (COP) is lower than the ESE heat pump when considering a single-resonance filter. The performance characteristics of the ESE heat pumps in the total momentum filtering condition are generally superior to those with a conventional filtering mechanism. In particular, the performance characteristics of the ESE heat pumps considering a conventional filtering mechanism are vastly different from those of a device with total momentum filtering, which is induced by extra electron momentum in addition to the horizontal direction. Parameters such as resonance width and energy spacing are found to be associated with the performance of the electron system.
Directory of Open Access Journals (Sweden)
B. Shank
2014-11-01
Full Text Available We present a detailed thermal and electrical model of superconducting transition edge sensors (TESs connected to quasiparticle (qp traps, such as the W TESs connected to Al qp traps used for CDMS (Cryogenic Dark Matter Search Ge and Si detectors. We show that this improved model, together with a straightforward time-domain optimal filter, can be used to analyze pulses well into the nonlinear saturation region and reconstruct absorbed energies with optimal energy resolution.
Shank, B; Cabrera, B; Kreikebaum, J M; Moffatt, R; Redl, P; Young, B A; Brink, P L; Cherry, M; Tomada, A
2014-01-01
We present a detailed thermal and electrical model of superconducting transition edge sensors (TESs) connected to quasiparticle (qp) traps, such as the W TESs connected to Al qp traps used for CDMS (Cryogenic Dark Matter Search) Ge and Si detectors. We show that this improved model, together with a straightforward time-domain optimal filter, can be used to analyze pulses well into the nonlinear saturation region and reconstruct absorbed energies with optimal energy resolution.
Optimal Linear Filters for Pulse Height Measurements in the Presence of Noise
Energy Technology Data Exchange (ETDEWEB)
Nygaard, K.
1966-07-15
For measurements of nuclear pulse height spectra a linear filter is used between the pulse amplifier and the pulse height recorder so as to improve the signal/noise ratio. The problem of finding the optimal filter is investigated with emphasis on technical realizability. The maximum available signal/noise ratio is theoretically calculated on the basis of all the information which can be found in the output of the pulse amplifier, and on an assumed a priori knowledge of the pulse time of arrival. It is then shown that the maximum available signal/noise ratio can be obtained with practical measurements without any a priori knowledge of pulse time of arrival, and a general description of the optimal linear filter is given. The solution is unique, technically realizable, and based solely on data (noise power spectrum and pulse shape) which can be measured at the output terminals of the pulse amplifier used.
Institute of Scientific and Technical Information of China (English)
Hong-Ling Ye; Wei-Wei Wang; Ning Chen; Yun-Kang Sui
2016-01-01
In this paper, a model of topology optimization with linear buckling constraints is established based on an independent and continuous mapping method to minimize the plate/shell structure weight. A composite exponential function (CEF) is selected as filtering functions for element weight, the element stiffness matrix and the element geomet-ric stiffness matrix, which recognize the design variables, and to implement the changing process of design variables from“discrete”to“continuous”and back to“discrete”. The buck-ling constraints are approximated as explicit formulations based on the Taylor expansion and the filtering function. The optimization model is transformed to dual programming and solved by the dual sequence quadratic programming algo-rithm. Finally, three numerical examples with power function and CEF as filter function are analyzed and discussed to demonstrate the feasibility and efficiency of the proposed method.
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.
A Temperature-to-Digital Converter Based on an Optimized Electrothermal Filter
Kashmiri, S.M.; Xia, S.; Makinwa, K.A.A.
2009-01-01
This paper describes the design of a CMOS temperature-to-digital converter (TDC). It operates by measuring the temperature-dependent phase shift of an electrothermal filter (ETF). Compared to previous work, this TDC employs an ETF whose layout has been optimized to minimize the thermal phase spread
Optimization of Field Development Scheduling, East Unity Oil Field, Sudan
Directory of Open Access Journals (Sweden)
Tagwa A. Musa
2005-01-01
Full Text Available In order to improve the reservoir performance in East Unity oil field Sudan, the studies focused on characterization, modeling and simulation of the actual performance and future development. A model was constructed using a three-phase, three dimensional, black oil simulator (ECLIPSE. In this study a data from East Unity oil field Sudan started production at July 1999 was used to perform the optimal oil rate and designing the best location of the new operating wells. Cumulative oil production, oil production rate, Water cut and recovery factor were used as key criteria to see if adding new wells in the area under study are economic risk.
Linear variable filter optimization for emergency response chemical detection and discrimination
Shen, Sylvia S.; Lewis, Paul E.
2010-08-01
Linear variable filter design and fabrication for LWIR is now commercially available for use in the development of remote sensing systems. The linear variable filter is attached directly to the cold shield of the focal plane array. The resulting compact spectrometer assemblies are completely contained in the Dewar system. This approach eliminates many of the wavelength calibration problems associated with current prism and grating systems and also facilitates the cost effective design and fabrication of aerial sensing systems for specific applications. This paper describes a study that was conducted with the following three objectives: 1) Determine if a multi-channel linear-variable-filter-based line scanner system can be used to discriminate a set of chemical vapors that represent a high probability of occurrence during a typical emergency response chemical incident; 2) Determine which multi-channel linear variable filter design is optimal; and 3) Determine the acceptable instrument noise equivalent spectral radiance for this application. A companion paper describes a separate study that was conducted to determine the concentration levels at which detection and discrimination can be achieved for the various chemicals based on the optimal filter design under various degrees of imperfect atmospheric correction.
Comparison of Kalman filter and optimal smoother estimates of spacecraft attitude
Sedlak, J.
1994-01-01
Given a valid system model and adequate observability, a Kalman filter will converge toward the true system state with error statistics given by the estimated error covariance matrix. The errors generally do not continue to decrease. Rather, a balance is reached between the gain of information from new measurements and the loss of information during propagation. The errors can be further reduced, however, by a second pass through the data with an optimal smoother. This algorithm obtains the optimally weighted average of forward and backward propagating Kalman filters. It roughly halves the error covariance by including future as well as past measurements in each estimate. This paper investigates whether such benefits actually accrue in the application of an optimal smoother to spacecraft attitude determination. Tests are performed both with actual spacecraft data from the Extreme Ultraviolet Explorer (EUVE) and with simulated data for which the true state vector and noise statistics are exactly known.
Optimization of Filter by using Support Vector Regression Machine with Cuckoo Search Algorithm
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M. İlarslan
2014-09-01
Full Text Available Herein, a new methodology using a 3D Electromagnetic (EM simulator-based Support Vector Regression Machine (SVRM models of base elements is presented for band-pass filter (BPF design. SVRM models of elements, which are as fast as analytical equations and as accurate as a 3D EM simulator, are employed in a simple and efficient Cuckoo Search Algorithm (CSA to optimize an ultra-wideband (UWB microstrip BPF. CSA performance is verified by comparing it with other Meta-Heuristics such as Genetic Algorithm (GA and Particle Swarm Optimization (PSO. As an example of the proposed design methodology, an UWB BPF that operates between the frequencies of 3.1 GHz and 10.6 GHz is designed, fabricated and measured. The simulation and measurement results indicate in conclusion the superior performance of this optimization methodology in terms of improved filter response characteristics like return loss, insertion loss, harmonic suppression and group delay.
Optimization of spectrally selective Si/SiO2 based filters for thermophotovoltaic devices
Khosroshahi, Farhad Kazemi; Ertürk, Hakan; Pınar Mengüç, M.
2017-08-01
Design of a spectrally selective filter based on one-dimensional Si/SiO2 layers is considered for improved performance of thermo-photovoltaic devices. Spectrally selective filters transmit only the convertible radiation from the emitter as non-convertible radiation leads to a reduction in cell efficiency due to heating. The presented Si/SiO2 based filter concept reflects the major part of the undesired range back to the emitter to minimize energy required for the process and it is adaptable to different types of cells and emitters with different temperatures since its cut-off wavelength can be tuned. While this study mainly focuses on InGaSb based thermo-photovoltaic cell, Si, GaSb, and Ga0.78In0.22As0.19Sb0.81 based cells are also examined. Transmittance of the structure is predicted by rigorous coupled wave approach. Genetic algorithm, which is a global optimization method, is used to find the best possible filter structure by considering the overall efficiency as an objective function that is maximized. The simulations show that significant enhancement in the overall system and device efficiency is possible by using such filters with TPV devices. The methodology described in this paper allows for an improved filter design procedure for selected applications.
Directory of Open Access Journals (Sweden)
Shaoxing Hu
2015-11-01
Full Text Available Aiming at addressing the problem of high computational cost of the traditional Kalman filter in SINS/GPS, a practical optimization algorithm with offline-derivation and parallel processing methods based on the numerical characteristics of the system is presented in this paper. The algorithm exploits the sparseness and/or symmetry of matrices to simplify the computational procedure. Thus plenty of invalid operations can be avoided by offline derivation using a block matrix technique. For enhanced efficiency, a new parallel computational mechanism is established by subdividing and restructuring calculation processes after analyzing the extracted “useful” data. As a result, the algorithm saves about 90% of the CPU processing time and 66% of the memory usage needed in a classical Kalman filter. Meanwhile, the method as a numerical approach needs no precise-loss transformation/approximation of system modules and the accuracy suffers little in comparison with the filter before computational optimization. Furthermore, since no complicated matrix theories are needed, the algorithm can be easily transplanted into other modified filters as a secondary optimization method to achieve further efficiency.
Hu, Shaoxing; Xu, Shike; Wang, Duhu; Zhang, Aiwu
2015-11-11
Aiming at addressing the problem of high computational cost of the traditional Kalman filter in SINS/GPS, a practical optimization algorithm with offline-derivation and parallel processing methods based on the numerical characteristics of the system is presented in this paper. The algorithm exploits the sparseness and/or symmetry of matrices to simplify the computational procedure. Thus plenty of invalid operations can be avoided by offline derivation using a block matrix technique. For enhanced efficiency, a new parallel computational mechanism is established by subdividing and restructuring calculation processes after analyzing the extracted "useful" data. As a result, the algorithm saves about 90% of the CPU processing time and 66% of the memory usage needed in a classical Kalman filter. Meanwhile, the method as a numerical approach needs no precise-loss transformation/approximation of system modules and the accuracy suffers little in comparison with the filter before computational optimization. Furthermore, since no complicated matrix theories are needed, the algorithm can be easily transplanted into other modified filters as a secondary optimization method to achieve further efficiency.
Design Optimization of Vena Cava Filters: An application to dual filtration devices
Energy Technology Data Exchange (ETDEWEB)
Singer, M A; Wang, S L; Diachin, D P
2009-12-03
Pulmonary embolism (PE) is a significant medical problem that results in over 300,000 fatalities per year. A common preventative treatment for PE is the insertion of a metallic filter into the inferior vena cava that traps thrombi before they reach the lungs. The goal of this work is to use methods of mathematical modeling and design optimization to determine the configuration of trapped thrombi that minimizes the hemodynamic disruption. The resulting configuration has implications for constructing an optimally designed vena cava filter. Computational fluid dynamics is coupled with a nonlinear optimization algorithm to determine the optimal configuration of trapped model thrombus in the inferior vena cava. The location and shape of the thrombus are parameterized, and an objective function, based on wall shear stresses, determines the worthiness of a given configuration. The methods are fully automated and demonstrate the capabilities of a design optimization framework that is broadly applicable. Changes to thrombus location and shape alter the velocity contours and wall shear stress profiles significantly. For vena cava filters that trap two thrombi simultaneously, the undesirable flow dynamics past one thrombus can be mitigated by leveraging the flow past the other thrombus. Streamlining the shape of thrombus trapped along the cava wall reduces the disruption to the flow, but increases the area exposed to abnormal wall shear stress. Computer-based design optimization is a useful tool for developing vena cava filters. Characterizing and parameterizing the design requirements and constraints is essential for constructing devices that address clinical complications. In addition, formulating a well-defined objective function that quantifies clinical risks and benefits is needed for designing devices that are clinically viable.
Optimal Design of High-Order Passive-Damped Filters for Grid-Connected Applications
DEFF Research Database (Denmark)
Beres, Remus Narcis; Wang, Xiongfei; Blaabjerg, Frede
2016-01-01
design procedures, the proposed method simplifies the iterative design of the overall filter while ensuring the minimum resonance peak with a lower damping capacitor and a lower rated resistor. It is shown that there is only one optimal value of the damping resistor or quality factor to achieve a minimum......Harmonic stability problems caused by the resonance of high-order filters in power electronic systems are ever increasing. The use of passive damping does provide a robust solution to address these issues, but at the price of reduced efficiency due to the presence of additional passive components...
Joint state and parameter estimation in particle filtering and stochastic optimization
Institute of Scientific and Technical Information of China (English)
Xiaojun YANG; Keyi XING; Kunlin SHI; Quan PAN
2008-01-01
In this paper,an adaptive estimation algorithm is proposed for non-linear dynamic systems with unknown static parameters based on combination of particle filtering and Simultaneous Perturbation Stochastic Approximation(SPSA)technique.The estimations of parameters are obtained by maximum-likelihood estimation and sampling within particle filtering framework,and the SPSA is used for stochastic optimization and to approximate the gradient of the cost function.The proposed algorithm achieves combined estimation of dynamic state and static parameters of nonlinear systerns.Simulation result demonstrates the feasibility and efficiency of the proposed algorithm.
A Filter-Based Uniform Algorithm for Optimizing Top-k Query in Distributed Networks
Institute of Scientific and Technical Information of China (English)
ZHAO Zhibin; YAO Lan; YANG Xiaochun; LI Binyang; YU Ge
2006-01-01
In this paper we propose a Filter-based Uniform Algorithm (FbUA) for optimizing top-k query in distributed networks, which has been a topic of much recent interest.The basic idea of FbUA is to set a filter at each node to prevent it from sending out the data with little chance to contribute to the top-k result.FbUA can gain exact answers to top-k query through two phrases of round-trip communications between query station and participant nodes.The experiment results show that FbUA reduces network bandwidth consumption dramatically.
Edge detection of potential field data using improved local phase filter
Ma, Guoqing
2013-01-01
Edge detection is a requisite task in the interpretation of potential field data. There are many high-pass filters based on horizontal and vertical derivatives in use, such as total horizontal derivative, tilt angle, theta map, et al. In this paper, we present a new edge detection filter, which uses the combination of the different order horizontal derivatives to delineate the edges of the sources, called improved local phase (ILP) filter. The new filter is computationally stable, as it does not need the computation of the vertical derivatives of potential field data. The new filter is tested on synthetic and real potential field data. The resolving power of the ILP filter is tested by comparing the results with those obtained by the other filters. The advantage of the ILP filter in the edge detection of potential field data is due to the fact that it can display the edges of the causative sources more precisely and clearly, and can bring out more subtle details.
Energy Technology Data Exchange (ETDEWEB)
Wakai, Nobuhide, E-mail: wakai@naramed-u.ac.jp [Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan and Department of Radiation Oncology, Nara Medical University, Kashihara, Nara 634-8522 (Japan); Sumida, Iori; Otani, Yuki; Suzuki, Osamu; Seo, Yuji; Isohashi, Fumiaki; Yoshioka, Yasuo; Ogawa, Kazuhiko [Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871 (Japan); Hasegawa, Masatoshi [Department of Radiation Oncology, Nara Medical University, Kashihara, Nara 634-8522 (Japan)
2015-05-15
Purpose: The authors sought to determine the optimal collimator leaf margins which minimize normal tissue dose while achieving high conformity and to evaluate differences between the use of a flattening filter-free (FFF) beam and a flattening-filtered (FF) beam. Methods: Sixteen lung cancer patients scheduled for stereotactic body radiotherapy underwent treatment planning for a 7 MV FFF and a 6 MV FF beams to the planning target volume (PTV) with a range of leaf margins (−3 to 3 mm). Forty grays per four fractions were prescribed as a PTV D95. For PTV, the heterogeneity index (HI), conformity index, modified gradient index (GI), defined as the 50% isodose volume divided by target volume, maximum dose (Dmax), and mean dose (Dmean) were calculated. Mean lung dose (MLD), V20 Gy, and V5 Gy for the lung (defined as the volumes of lung receiving at least 20 and 5 Gy), mean heart dose, and Dmax to the spinal cord were measured as doses to organs at risk (OARs). Paired t-tests were used for statistical analysis. Results: HI was inversely related to changes in leaf margin. Conformity index and modified GI initially decreased as leaf margin width increased. After reaching a minimum, the two values then increased as leaf margin increased (“V” shape). The optimal leaf margins for conformity index and modified GI were −1.1 ± 0.3 mm (mean ± 1 SD) and −0.2 ± 0.9 mm, respectively, for 7 MV FFF compared to −1.0 ± 0.4 and −0.3 ± 0.9 mm, respectively, for 6 MV FF. Dmax and Dmean for 7 MV FFF were higher than those for 6 MV FF by 3.6% and 1.7%, respectively. There was a positive correlation between the ratios of HI, Dmax, and Dmean for 7 MV FFF to those for 6 MV FF and PTV size (R = 0.767, 0.809, and 0.643, respectively). The differences in MLD, V20 Gy, and V5 Gy for lung between FFF and FF beams were negligible. The optimal leaf margins for MLD, V20 Gy, and V5 Gy for lung were −0.9 ± 0.6, −1.1 ± 0.8, and −2.1 ± 1.2 mm, respectively, for 7 MV FFF compared
Improved design and optimization of subsurface flow constructed wetlands and sand filters
Brovelli, A.; Carranza-Díaz, O.; Rossi, L.; Barry, D. A.
2010-05-01
Subsurface flow constructed wetlands and sand filters are engineered systems capable of eliminating a wide range of pollutants from wastewater. These devices are easy to operate, flexible and have low maintenance costs. For these reasons, they are particularly suitable for small settlements and isolated farms and their use has substantially increased in the last 15 years. Furthermore, they are also becoming used as a tertiary - polishing - step in traditional treatment plants. Recent work observed that research is however still necessary to understand better the biogeochemical processes occurring in the porous substrate, their mutual interactions and feedbacks, and ultimately to identify the optimal conditions to degrade or remove from the wastewater both traditional and anthropogenic recalcitrant pollutants, such as hydrocarbons, pharmaceuticals, personal care products. Optimal pollutant elimination is achieved if the contact time between microbial biomass and the contaminated water is sufficiently long. The contact time depends on the hydraulic residence time distribution (HRTD) and is controlled by the hydrodynamic properties of the system. Previous reports noted that poor hydrodynamic behaviour is frequent, with water flowing mainly through preferential paths resulting in a broad HRTD. In such systems the flow rate must be decreased to allow a sufficient proportion of the wastewater to experience the minimum residence time. The pollutant removal efficiency can therefore be significantly reduced, potentially leading to the failure of the system. The aim of this work was to analyse the effect of the heterogeneous distribution of the hydraulic properties of the porous substrate on the HRTD and treatment efficiency, and to develop an improved design methodology to reduce the risk of system failure and to optimize existing systems showing poor hydrodynamics. Numerical modelling was used to evaluate the effect of substrate heterogeneity on the breakthrough curves of
A New Mutated Quantum-Behaved Particle Swarm Optimizer for Digital IIR Filter Design
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Wenbo Xu
2009-01-01
Full Text Available Adaptive infinite impulse response (IIR filters have shown their worth in a wide range of practical applications. Because the error surface of IIR filters is multimodal in most cases, global optimization techniques are required for avoiding local minima. In this paper, we employ a global optimization algorithm, Quantum-behaved particle swarm optimization (QPSO that was proposed by us previously, and its mutated version in the design of digital IIR filter. The mechanism in QPSO is based on the quantum behaviour of particles in a potential well and particle swarm optimization (PSO algorithm. QPSO is characterized by fast convergence, good search ability, and easy implementation. The mutated QPSO (MuQPSO is proposed in this paper by using a random vector in QPSO to increase the randomness and to enhance the global search ability. Experimental results on three examples show that QPSO and MuQPSO are superior to genetic algorithm (GA, differential evolution (DE algorithm, and PSO algorithm in quality, convergence speed, and robustness.
Interlaced optimal-REQUEST and unscented Kalman filtering for attitude determination
Institute of Scientific and Technical Information of China (English)
Quan Wei; Xu Liang; Zhang Huijuan; Fang Jiancheng
2013-01-01
Aimed at low accuracy of attitude determination because of using low-cost components which may result in non-linearity in integrated attitude determination systems,a novel attitude determination algorithm using vector observations and gyro measurements is presented.The various features of the unscented Kalman filter (UKF) and optimal-REQUEST (quaternion estimator) algorithms are introduced for attitude determination.An interlaced filtering method is presented for the attitude determination of nano-spacecraft by setting the quaternion as the attitude representation,using the UKF and optimal-REQUEST to estimate the gyro drifts and the quaternion,respectively.The optimal-REQUEST and UKF are not isolated from each other.When the optimal-REQUEST algorithm estimates the attitude quaternion,the gyro drifts are estimated by the UKF algorithm synchronously by using the estimated attitude quaternion.Furthermore,the speed of attitude determination is improved by setting the state dimension to three.Experimental results show that the presented method has higher performance in attitude determination compared to the UKF algorithm and the traditional interlaced filtering method and can estimate the gyro drifts quickly.
Design of FIR Filters with Discrete Coefficients using Ant Colony Optimization
Tsutsumi, Shuntaro; Suyama, Kenji
In this paper, we propose a new design method for linear phase FIR (Finite Impulse Response) filters with discrete coefficients. In a hardware implementation, filter coefficients must be represented as discrete values. The design problem of digital filters with discrete coefficients is formulated as the integer programming problem. Then, an enormous amount of computational time is required to solve the problem in a strict solver. Recently, ACO (Ant Colony Optimization) which is one heuristic approach, is used widely for solving combinational problem like the traveling salesman problem. In our method, we formulate the design problem as the 0-1 integer programming problem and solve it by using the ACO. Several design examples are shown to present effectiveness of the proposed method.
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.
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Suksan Tiyarachakun
2014-01-01
Full Text Available This paper presents a novel harmonic identification algorithm of shunt active power filter for balanced and unbalanced three-phase systems based on the instantaneous power theory called instantaneous power theory with Fourier. Moreover, the optimal design of predictive current controller using an artificial intelligence technique called adaptive Tabu search is also proposed in the paper. These enhancements of the identification and current control parts are the aim of the good performance for shunt active power filter. The good results for harmonic mitigation using the proposed ideas in the paper are confirmed by the intensive simulation using SPS in SIMULINK. The simulation results show that the enhanced shunt active power filter can provide the minimum %THD (Total Harmonic Distortion of source currents and unity power factor after compensation. In addition, the %THD also follows the IEEE Std.519-1992.
Vorobjev, Ivan A; Buchholz, Kathrin; Prabhat, Prashant; Ketman, Kenneth; Egan, Elizabeth S; Marti, Matthias; Duraisingh, Manoj T; Barteneva, Natasha S
2012-09-05
Malaria remains a major cause of morbidity and mortality worldwide. Flow cytometry-based assays that take advantage of fluorescent protein (FP)-expressing malaria parasites have proven to be valuable tools for quantification and sorting of specific subpopulations of parasite-infected red blood cells. However, identification of rare subpopulations of parasites using green fluorescent protein (GFP) labelling is complicated by autofluorescence (AF) of red blood cells and low signal from transgenic parasites. It has been suggested that cell sorting yield could be improved by using filters that precisely match the emission spectrum of GFP. Detection of transgenic Plasmodium falciparum parasites expressing either tdTomato or GFP was performed using a flow cytometer with interchangeable optical filters. Parasitaemia was evaluated using different optical filters and, after optimization of optics, the GFP-expressing parasites were sorted and analysed by microscopy after cytospin preparation and by imaging cytometry. A new approach to evaluate filter performance in flow cytometry using two-dimensional dot blot was developed. By selecting optical filters with narrow bandpass (BP) and maximum position of filter emission close to GFP maximum emission in the FL1 channel (510/20, 512/20 and 517/20; dichroics 502LP and 466LP), AF was markedly decreased and signal-background improve dramatically. Sorting of GFP-expressing parasite populations in infected red blood cells at 90 or 95% purity with these filters resulted in 50-150% increased yield when compared to the standard filter set-up. The purity of the sorted population was confirmed using imaging cytometry and microscopy of cytospin preparations of sorted red blood cells infected with transgenic malaria parasites. Filter optimization is particularly important for applications where the FP signal and percentage of positive events are relatively low, such as analysis of parasite-infected samples with in the intention of gene
Directory of Open Access Journals (Sweden)
Vorobjev Ivan A
2012-09-01
Full Text Available Abstract Background Malaria remains a major cause of morbidity and mortality worldwide. Flow cytometry-based assays that take advantage of fluorescent protein (FP-expressing malaria parasites have proven to be valuable tools for quantification and sorting of specific subpopulations of parasite-infected red blood cells. However, identification of rare subpopulations of parasites using green fluorescent protein (GFP labelling is complicated by autofluorescence (AF of red blood cells and low signal from transgenic parasites. It has been suggested that cell sorting yield could be improved by using filters that precisely match the emission spectrum of GFP. Methods Detection of transgenic Plasmodium falciparum parasites expressing either tdTomato or GFP was performed using a flow cytometer with interchangeable optical filters. Parasitaemia was evaluated using different optical filters and, after optimization of optics, the GFP-expressing parasites were sorted and analysed by microscopy after cytospin preparation and by imaging cytometry. Results A new approach to evaluate filter performance in flow cytometry using two-dimensional dot blot was developed. By selecting optical filters with narrow bandpass (BP and maximum position of filter emission close to GFP maximum emission in the FL1 channel (510/20, 512/20 and 517/20; dichroics 502LP and 466LP, AF was markedly decreased and signal-background improve dramatically. Sorting of GFP-expressing parasite populations in infected red blood cells at 90 or 95% purity with these filters resulted in 50-150% increased yield when compared to the standard filter set-up. The purity of the sorted population was confirmed using imaging cytometry and microscopy of cytospin preparations of sorted red blood cells infected with transgenic malaria parasites. Discussion Filter optimization is particularly important for applications where the FP signal and percentage of positive events are relatively low, such as analysis
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
This paper proposes a distributed denial-of-service attack detection method based on self similar and wavelet analysis. This method adopts an optimized transmission control protocol cookie technology for filter optimization in order to accurately detect and efficiently filter the traffic of distributed denial-of-service attack. This paper presents the design of our software, and describes all important algorithms of detection and filtering. Experimental results showed that our method has only a low delay to detect abnormal traffic of distributed denial-of-service attacks, and with a high percentage of filtering.
Quality classification of wooden surfaces using Gabor filters and genetic feature optimization
Poelzleitner, Wolfgang; Schwingskakl, Gert
1999-08-01
We apply a model of texture segmentation using multiple spatially and spectrally localized filters, known as Gabor filters, to the analysis of texture and effect regions found on wooden boards. Specifically we present a method to find an optimal set of parameters for a given 2D object detection method. The method uses banks of Gabor filters to limit the rang of spatial frequencies, where mutually distinct textures differ significantly in their dominant characterizing frequencies. By encoding images into multiple narrow spatial frequency and orientation channels a local classification of texture regions can be achieved. Unlike other methods applying Gabor filters, we do not use a full Gabor transform, but use feature selection techniques to maximize discrimination. The selection method uses a genetic algorithm to optimize various parameters of the system including Gabor weights, and the parameters of morphological pre-processing. We demonstrate the applicability of the method to the task of classifying wooden textures, and report experimental results using the proposed method.
Multiclass optical correlation filters for alphanumeric field recognition
Casasent, David P.; Gopalaswamy, Srinivasan; Iyer, Anand K.
1993-01-01
We consider the use of new distortion-invariant optical correlation filters for machine-printed OCR. Our work is unique in its treatment of a large set of different fonts, printer types, plus rotations and scale (point size) variations, and various practical issues such as printing artifacts and background noise. We detail their use in the locations and recognition of alphanumeric fluids (digits) in destination address blocks (DABs).
He, Yunlong; Zhao, Yanna; Ren, Yanju; Gee, James
2017-01-01
Filtering belongs to the most fundamental operations of retinal image processing and for which the value of the filtered image at a given location is a function of the values in a local window centered at this location. However, preserving thin retinal vessels during the filtering process is challenging due to vessels' small area and weak contrast compared to background, caused by the limited resolution of imaging and less blood flow in the vessel. In this paper, we present a novel retinal image denoising approach which is able to preserve the details of retinal vessels while effectively eliminating image noise. Specifically, our approach is carried out by determining an optimal spatial kernel for the bilateral filter, which is represented by a line spread function with an orientation and scale adjusted adaptively to the local vessel structure. Moreover, this approach can also be served as a preprocessing tool for improving the accuracy of the vessel detection technique. Experimental results show the superiority of our approach over state-of-the-art image denoising techniques such as the bilateral filter. PMID:28261320
On-Orbit Multi-Field Wavefront Control with a Kalman Filter
Lou, John; Sigrist, Norbert; Basinger, Scott; Redding, David
2008-01-01
A document describes a multi-field wavefront control (WFC) procedure for the James Webb Space Telescope (JWST) on-orbit optical telescope element (OTE) fine-phasing using wavefront measurements at the NIRCam pupil. The control is applied to JWST primary mirror (PM) segments and secondary mirror (SM) simultaneously with a carefully selected ordering. Through computer simulations, the multi-field WFC procedure shows that it can reduce the initial system wavefront error (WFE), as caused by random initial system misalignments within the JWST fine-phasing error budget, from a few dozen micrometers to below 50 nm across the entire NIRCam Field of View, and the WFC procedure is also computationally stable as the Monte-Carlo simulations indicate. With the incorporation of a Kalman Filter (KF) as an optical state estimator into the WFC process, the robustness of the JWST OTE alignment process can be further improved. In the presence of some large optical misalignments, the Kalman state estimator can provide a reasonable estimate of the optical state, especially for those degrees of freedom that have a significant impact on the system WFE. The state estimate allows for a few corrections to the optical state to push the system towards its nominal state, and the result is that a large part of the WFE can be eliminated in this step. When the multi-field WFC procedure is applied after Kalman state estimate and correction, the stability of fine-phasing control is much more certain. Kalman Filter has been successfully applied to diverse applications as a robust and optimal state estimator. In the context of space-based optical system alignment based on wavefront measurements, a KF state estimator can combine all available wavefront measurements, past and present, as well as measurement and actuation error statistics to generate a Maximum-Likelihood optimal state estimator. The strength and flexibility of the KF algorithm make it attractive for use in real-time optical system
Nonrigid registration with tissue-dependent filtering of the deformation field
Energy Technology Data Exchange (ETDEWEB)
Staring, Marius; Klein, Stefan; Pluim, Josien P W [Image Sciences Institute, University Medical Center Utrecht, PO Box 85500, 3508 GA, Room Q0S.459, Utrecht (Netherlands)
2007-12-07
In present-day medical practice it is often necessary to nonrigidly align image data. Current registration algorithms do not generally take the characteristics of tissue into account. Consequently, rigid tissue, such as bone, can be deformed elastically, growth of tumours may be concealed, and contrast-enhanced structures may be reduced in volume. We propose a method to locally adapt the deformation field at structures that must be kept rigid, using a tissue-dependent filtering technique. This adaptive filtering of the deformation field results in locally linear transformations without scaling or shearing. The degree of filtering is related to tissue stiffness: more filtering is applied at stiff tissue locations, less at parts of the image containing nonrigid tissue. The tissue-dependent filter is incorporated in a commonly used registration algorithm, using mutual information as a similarity measure and cubic B-splines to model the deformation field. The new registration algorithm is compared with this popular method. Evaluation of the proposed tissue-dependent filtering is performed on 3D computed tomography (CT) data of the thorax and on 2D digital subtraction angiography (DSA) images. The results show that tissue-dependent filtering of the deformation field leads to improved registration results: tumour volumes and vessel widths are preserved rather than affected.
Directory of Open Access Journals (Sweden)
Waad Bouaguel
2012-08-01
Full Text Available Filter selection techniques are known for their simplicity and efficiency. However this kind of methods doesn’t take into consideration the features inter-redundancy. Consequently the un-removed redundant features remain in the final classification model, giving lower generalization performance. In this paper we propose to use a mathematical optimization method that reduces inter-features redundancy and maximize relevance between each feature and the target variable.
Flat-top Drop Filter based on a Single Topology Optimized Photonic Crystal Cavity
DEFF Research Database (Denmark)
Frandsen, Lars Hagedorn; Elesin, Yuriy; Guan, Xiaowei
2015-01-01
Outperforming conventional design concepts, a flat-top drop filter has been designed byapplying 3D topology optimization to a single waveguide-coupled L3 photonic crystal cavity.Measurements on the design fabricated in silicon-on-insulator material reveal that the pass-band ofthe drop channel...... is flat within 0.44 dB over a wavelength range of 9.7 nm with an insertion losslower than 0.85 dB....
DEFF Research Database (Denmark)
Sørensen, Rene; Lund, Erik
2013-01-01
This extended abstract presents a new parameterization for performing discrete material and thickness optimization of laminated composite structures. The parameterization is based on the work by Sørensen and Lund 2013, where we present a reformulation of the original parameterization....... The reformulation eliminates the need for having explicit constraint for ensuring that intermediate void does not appear in between layers of the laminate. This is achieved by utilizing a filtering technique known as a casting constraint from traditional topology optimization with isotropic materials....
Optimal spectral filtering in soliton self-frequency shift for deep-tissue multiphoton microscopy
Wang, Ke; Qiu, Ping
2015-05-01
Tunable optical solitons generated by soliton self-frequency shift (SSFS) have become valuable tools for multiphoton microscopy (MPM). Recent progress in MPM using 1700 nm excitation enabled visualizing subcortical structures in mouse brain in vivo for the first time. Such an excitation source can be readily obtained by SSFS in a large effective-mode-area photonic crystal rod with a 1550-nm fiber femtosecond laser. A longpass filter was typically used to isolate the soliton from the residual in order to avoid excessive energy deposit on the sample, which ultimately leads to optical damage. However, since the soliton was not cleanly separated from the residual, the criterion for choosing the optimal filtering wavelength is lacking. Here, we propose maximizing the ratio between the multiphoton signal and the n'th power of the excitation pulse energy as a criterion for optimal spectral filtering in SSFS when the soliton shows dramatic overlapping with the residual. This optimization is based on the most efficient signal generation and entirely depends on physical quantities that can be easily measured experimentally. Its application to MPM may reduce tissue damage, while maintaining high signal levels for efficient deep penetration.
Deso, Steven E; Idakoji, Ibrahim A; Muelly, Michael C; Kuo, William T
2016-06-01
Owing to a myriad of inferior vena cava (IVC) filter types and their potential complications, rapid and correct identification may be challenging when encountered on routine imaging. The authors aimed to develop an interactive mobile application that allows recognition of all IVC filters and related complications, to optimize the care of patients with indwelling IVC filters. The FDA Premarket Notification Database was queried from 1980 to 2014 to identify all IVC filter types in the United States. An electronic search was then performed on MEDLINE and the FDA MAUDE database to identify all reported complications associated with each device. High-resolution photos were taken of each filter type and corresponding computed tomographic and fluoroscopic images were obtained from an institutional review board-approved IVC filter registry. A wireframe and storyboard were created, and software was developed using HTML5/CSS compliant code. The software was deployed using PhoneGap (Adobe, San Jose, CA), and the prototype was tested and refined. Twenty-three IVC filter types were identified for inclusion. Safety data from FDA MAUDE and 72 relevant peer-reviewed studies were acquired, and complication rates for each filter type were highlighted in the application. Digital photos, fluoroscopic images, and CT DICOM files were seamlessly incorporated. All data were succinctly organized electronically, and the software was successfully deployed into Android (Google, Mountain View, CA) and iOS (Apple, Cupertino, CA) platforms. A powerful electronic mobile application was successfully created to allow rapid identification of all IVC filter types and related complications. This application may be used to optimize the care of patients with IVC filters.
Optimization of interference filters with genetic algorithms applied to silver-based heat mirrors.
Eisenhammer, T; Lazarov, M; Leutbecher, M; Schöffel, U; Sizmann, R
1993-11-01
In the optimization of multilayer stacks for various optical filtering purposes not only the thicknesses of the thin films are to be optimized, but also the sequence of materials. Materials with very different optical properties, such as metals and dielectrics, may be combined. A genetic algorithm is introduced to search for the optimal sequence of materials along with their optical thicknesses. This procedure is applied to a heat mirror in combination with a blackbody absorber for thermal solar energy applications at elevated temperatures (250 °C). The heat mirror is based on silver films with antireflective dielectric layers. Seven dielectrics have been considered. For a five-layer stack the sequence (TiO(2)/Ag/TiO(2)/Ag/Y(2)O(3)) is found to be optimal.
Namin, Frank Farhad A.
(photonic resonance) and the plasmonic response of the spheres (plasmonic resonance). In particular the couplings between the photonic and plasmonic modes are studied. In periodic arrays this coupling leads to the formation of a so called photonic-plasmonic hybrid mode. The formation of hybrid modes is studied in quasicrystalline arrays. Quasicrystalline structures in essence possess several periodicities which in some cases can lead to the formation of multiple hybrid modes with wider bandwidths. It is also demonstrated that the performance of these arrays can be further enhanced by employing a perturbation method. The second property considered is local field enhancements in quasicrystalline arrays of gold nanospheres. It will be shown that despite a considerably smaller filling factor quasicrystalline arrays generate larger local field enhancements which can be even further enhanced by optimally placing perturbing spheres within the prototiles that comprise the aperiodic arrays. The second thrust of research in this dissertation focuses on designing all-dielectric filters and metamaterial coatings for the optical range. In higher frequencies metals tend to have a high loss and thus they are not suitable for many applications. Hence dielectrics are used for applications in optical frequencies. In particular we focus on designing two types of structures. First a near-perfect optical mirror is designed. The design is based on optimizing a subwavelength periodic dielectric grating to obtain appropriate effective parameters that will satisfy the desired perfect mirror condition. Second, a broadband anti-reflective all-dielectric grating with wide field of view is designed. The second design is based on a new computationally efficient genetic algorithm (GA) optimization method which shapes the sidewalls of the grating based on optimizing the roots of polynomial functions.
Directory of Open Access Journals (Sweden)
Sebastian Andersson
2015-01-01
Full Text Available Accelerometers and gyroscope are often referred to as inertial sensors. They detect movement and are used for motion tracking systems in many fields. In recent years they have become much smaller, lighter and cheaper which makes them attractive for use in consumer electronics. The goal of this research is to use all these advantages to create a cheap, low cost and accurate motion tracking system. The system that will be developed is using two pairs of accelerometer + gyroscope sensors which communicates with an iOS device using BLE. The sensors are attached to a persons leg to capture the orientation of the leg while walking or running. Studying the movements of a persons leg can be useful regarding both performance and health aspects. To create the system, usage of inertial sensors and how to combine their data using the complementary filter have been studied. Further, several experiments were made to optimize the filter design for this kind of movement. The results shows how the orientation estimation differs in accuracy depending on different values of how the filter is designed. However, by using the right values, a fairly accurate orientation of the leg can be estimated which is proved by the simple visualization of the iOS application.
Simulation of RF data with tissue motion for optimizing stationary echo canceling filters
DEFF Research Database (Denmark)
Schlaikjer, Malene; Torp-Pedersen, S.; Jensen, Jørgen Arendt
2003-01-01
Blood velocity estimation is complicated by the strong echoes received from tissue surrounding the vessel under investigation. Proper blood velocity estimation necessitates use of a filter for separation of the different signal components. Development of these filters and new estimators requires RF......-data, where the tissue component is known. In vivo RF-data does not have this property. Instead simulated data incorporating all relevant features of the measurement situation can be employed. One feature is the motion in the surrounding tissue induced by pulsation, heartbeat, and breathing. This study has...... developed models for the motions and incorporated them into the RF simulation program Field II, thereby obtaining realistic simulated data. A powerful tool for evaluation of different filters and estimators is then available. The model parameters can be varied according to the physical situation...
Memory Optimization for Phase-field Simulations
Energy Technology Data Exchange (ETDEWEB)
Derek Gaston; John Peterson; Andrew Slaughter; Cody Permann; David Andrs
2014-08-01
Phase-field simulations are computationally and memory intensive applications. Many of the phase-field simulations being conducted in support of NEAMS were not capable of running on “normal clusters” with 2-4GB of RAM per core, and instead required specialized “big-memory” clusters with 64GB per core. To address this issue, the MOOSE team developed a new Python-based utility called MemoryLogger, and applied it to locate, diagnose, and eradicate memory bottlenecks within the MOOSE framework. MemoryLogger allows for a better understanding of the memory usage of an application being run in parallel across a cluster. Memory usage information is captured for every individual process in a parallel job, and communicated to the head node of the cluster. Console text output from the application itself is automatically matched with this memory usage information to produce a detailed picture of memory usage over time, making it straightforward to identify the subroutines which contribute most to the application’s peak memory usage. The information produced by the MemoryLogger quickly and effectively narrows the search for memory optimizations to the most data-intensive parts of the simulation.
Directory of Open Access Journals (Sweden)
Apoorva Aggarwal
2015-12-01
Full Text Available In this paper, an optimal design of linear phase digital finite impulse response (FIR highpass (HP filter using the L1-norm based real-coded genetic algorithm (RCGA is investigated. A novel fitness function based on L1 norm is adopted to enhance the design accuracy. Optimized filter coefficients are obtained by defining the filter objective function in L1 sense using RCGA. Simulation analysis unveils that the performance of the RCGA adopting this fitness function is better in terms of signal attenuation ability of the filter, flatter passband and the convergence rate. Observations are made on the percentage improvement of this algorithm over the gradient-based L1 optimization approach on various factors by a large amount. It is concluded that RCGA leads to the best solution under specified parameters for the FIR filter design on account of slight unnoticeable higher transition width.
Pacheco, Sara E; Anderson, Linnea M; Boekelheide, Kim
2012-01-01
Quantifying testicular homogenization-resistant spermatid heads (HRSH) is a powerful indicator of spermatogenesis. These counts have traditionally been performed manually using a hemocytometer, but this method can be time consuming and biased. We aimed to develop a protocol to reduce debris for the application of automated counting, which would allow for efficient and unbiased quantification of rat HRSH. We developed a filter-lysis protocol that effectively removes debris from rat testicular homogenates. After filtering and lysing the homogenates, we found no statistical differences between manual (classic and filter-lysis) and automated (filter-lysis) counts using 1-way analysis of variance with Bonferroni's multiple comparison test. In addition, Pearson's correlation coefficients were calculated to compare the counting methods, and there was a strong correlation between the classic manual counts and the filter-lysis manual (r = 0.85, P = .002) and the filter-lysis automated (r = 0.89, P = .0005) counts. We also tested the utility of the automated method in a low-dose exposure model known to decrease HRSH. Adult Fischer 344 rats exposed to 0.33% 2,5-hexanedione in the drinking water for 12 weeks demonstrated decreased body (P = .02) and testes (P = .002) weights. In addition, there was a significant reduction in the number of HRSH per testis (P = .002) when compared to controls. A filterlysis protocol was optimized to purify rat testicular homogenates for automated HRSH counts. Automated counting systems yield unbiased data and can be applied to detect changes in the testis after low-dose toxicant exposure.
Directory of Open Access Journals (Sweden)
Piljae Kim
2011-11-01
Full Text Available In this study, the concept of the chemical substance pheromone is utilized for the robotic tasks. This paperfirst illustrates the model of pheromone-based potential field. The field is constructed through theinteraction between mobile robots and data carriers, such as RFID tags. The emphasis in the modeling ofthe system is on the possibility of the practical implementable ideas. The stability analysis of thepheromone potential field is carried out also aiming at the implementation on a real robotic environment.The comprehensive analysis on stability provides the criteria for how the parameters are to be set for theproper potential field, and has led to a new filter design scheme called pheromone filter, which satisfiesboth the stability and accuracy of the field. The unique structures of both the revised mobile robot and thedesigned filter show that the proposed method facilitates a more straightforward and practicalimplementation.
Moment-tensor solutions estimated using optimal filter theory: Global seismicity, 2001
Sipkin, S.A.; Bufe, C.G.; Zirbes, M.D.
2003-01-01
This paper is the 12th in a series published yearly containing moment-tensor solutions computed at the US Geological Survey using an algorithm based on the theory of optimal filter design (Sipkin, 1982 and Sipkin, 1986b). An inversion has been attempted for all earthquakes with a magnitude, mb or MS, of 5.5 or greater. Previous listings include solutions for earthquakes that occurred from 1981 to 2000 (Sipkin, 1986b; Sipkin and Needham, 1989, Sipkin and Needham, 1991, Sipkin and Needham, 1992, Sipkin and Needham, 1993, Sipkin and Needham, 1994a and Sipkin and Needham, 1994b; Sipkin and Zirbes, 1996 and Sipkin and Zirbes, 1997; Sipkin et al., 1998, Sipkin et al., 1999, Sipkin et al., 2000a, Sipkin et al., 2000b and Sipkin et al., 2002).The entire USGS moment-tensor catalog can be obtained via anonymous FTP at ftp://ghtftp.cr.usgs.gov. After logging on, change directory to “momten”. This directory contains two compressed ASCII files that contain the finalized solutions, “mt.lis.Z” and “fmech.lis.Z”. “mt.lis.Z” contains the elements of the moment tensors along with detailed event information; “fmech.lis.Z” contains the decompositions into the principal axes and best double-couples. The fast moment-tensor solutions for more recent events that have not yet been finalized and added to the catalog, are gathered by month in the files “jan01.lis.Z”, etc. “fmech.doc.Z” describes the various fields.
Sangeetha, S.; Sureka, C. S.
2017-06-01
The present study is focused to compare the characteristics of Varian Clinac 600 C/D flattened and unflattened 6 MV photon beams for small field dosimetry using EGSnrc Monte Carlo Simulation since the small field dosimetry is considered to be the most crucial and provoking task in the field of radiation dosimetry. A 6 MV photon beam of a Varian Clinac 600 C/D medical linear accelerator operates with Flattening Filter (FF) and Flattening-Filter-Free (FFF) mode for small field dosimetry were performed using EGSnrc Monte Carlo user codes (BEAMnrc and DOSXYZnrc) in order to calculate the beam characteristics using Educated-trial and error method. These includes: Percentage depth dose, lateral beam profile, dose rate delivery, photon energy spectra, photon beam uniformity, out-of-field dose, surface dose, penumbral dose and output factor for small field dosimetry (0.5×0.5 cm2 to 4×4 cm2) and are compared with magna-field sizes (5×5 cm2 to 40×40 cm2) at various depths. The results obtained showed that the optimized beam energy and Full-width-half maximum value for small field dosimetry and magna-field dosimetry was found to be 5.7 MeV and 0.13 cm for both FF and FFF beams. The depth of dose maxima for small field size deviates minimally for both FF and FFF beams similar to magna-fields. The depths greater than dmax depicts a steeper dose fall off in the exponential region for FFF beams comparing FF beams where its deviations gets increased with the increase in field size. The shape of the lateral beam profiles of FF and FFF beams varies remains similar for the small field sizes less than 4×4 cm2 whereas it varies in the case of magna-fields. Dose rate delivery for FFF beams shows an eminent increase with a two-fold factor for both small field dosimetry and magna-field sizes. The surface dose measurements of FFF beams for small field size were found to be higher whereas it gets lower for magna-fields than FF beam. The amount of out-of-field dose reduction gets
Kuldeep, B; Singh, V K; Kumar, A; Singh, G K
2015-01-01
In this article, a novel approach for 2-channel linear phase quadrature mirror filter (QMF) bank design based on a hybrid of gradient based optimization and optimization of fractional derivative constraints is introduced. For the purpose of this work, recently proposed nature inspired optimization techniques such as cuckoo search (CS), modified cuckoo search (MCS) and wind driven optimization (WDO) are explored for the design of QMF bank. 2-Channel QMF is also designed with particle swarm optimization (PSO) and artificial bee colony (ABC) nature inspired optimization techniques. The design problem is formulated in frequency domain as sum of L2 norm of error in passband, stopband and transition band at quadrature frequency. The contribution of this work is the novel hybrid combination of gradient based optimization (Lagrange multiplier method) and nature inspired optimization (CS, MCS, WDO, PSO and ABC) and its usage for optimizing the design problem. Performance of the proposed method is evaluated by passband error (ϕp), stopband error (ϕs), transition band error (ϕt), peak reconstruction error (PRE), stopband attenuation (As) and computational time. The design examples illustrate the ingenuity of the proposed method. Results are also compared with the other existing algorithms, and it was found that the proposed method gives best result in terms of peak reconstruction error and transition band error while it is comparable in terms of passband and stopband error. Results show that the proposed method is successful for both lower and higher order 2-channel QMF bank design. A comparative study of various nature inspired optimization techniques is also presented, and the study singles out CS as a best QMF optimization technique. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.
2014-11-01
for Time Accurate Compressible Large Eddy Simulations : Comparison of Artificial Dissipation and Filtering Schemes 5b. GRANT NUMBER 5c. PROGRAM...Optimal Numerical Schemes for Time Accurate Compressible Large Eddy Simulations : Comparison of Artificial Dissipation and Filtering Schemes 67th
Wang, Li-Qi; Ge, Hui-Fang; Li, Gui-Bin; Yu, Dian-Yu; Hu, Li-Zhi; Jiang, Lian-Zhou
2014-04-01
Combining classical Kalman filter with NIR analysis technology, a new method of characteristic wavelength variable selection, namely Kalman filtering method, is presented. The principle of Kalman filter for selecting optimal wavelength variable was analyzed. The wavelength selection algorithm was designed and applied to NIR detection of soybean oil acid value. First, the PLS (partial leastsquares) models were established by using different absorption bands of oil. The 4 472-5 000 cm(-1) characteristic band of oil acid value, including 132 wavelengths, was selected preliminarily. Then the Kalman filter was used to select characteristic wavelengths further. The PLS calibration model was established using selected 22 characteristic wavelength variables, the determination coefficient R2 of prediction set and RMSEP (root mean squared error of prediction) are 0.970 8 and 0.125 4 respectively, equivalent to that of 132 wavelengths, however, the number of wavelength variables was reduced to 16.67%. This algorithm is deterministic iteration, without complex parameters setting and randomicity of variable selection, and its physical significance was well defined. The modeling using a few selected characteristic wavelength variables which affected modeling effect heavily, instead of total spectrum, can make the complexity of model decreased, meanwhile the robustness of model improved. The research offered important reference for developing special oil near infrared spectroscopy analysis instruments on next step.
Turini, G; Condino, S; Stecco, A; Ferrari, V; Ferrari, M; Gesi, M
2015-08-01
In the last few years, there has been an increasing interest in the role of deep fascia mobility in musculoskeletal dynamics and chronic pain mechanisms. In a previous paper we presented an innovative semiautomatic approach to evaluate the 3D motion of the fascia using ultrasound (US) imaging, generating a sparse deformation vector field. This paper presents an improvement of our original method, focusing on the filtering of the sparse vector field and its validation. Moreover, in order to evaluate the performance of the algorithm, a method is proposed to generate synthetic deformation vector fields, including: expansion, rotation, horizontal shear, and oblique shear components. Preliminary tests on the final synthetic deformation vector fields showed promising results. Further experiments are required in order to optimize the tuning of the algorithm.
An Image Filter Based on Shearlet Transformation and Particle Swarm Optimization Algorithm
Directory of Open Access Journals (Sweden)
Kai Hu
2015-01-01
Full Text Available Digital image is always polluted by noise and made data postprocessing difficult. To remove noise and preserve detail of image as much as possible, this paper proposed image filter algorithm which combined the merits of Shearlet transformation and particle swarm optimization (PSO algorithm. Firstly, we use classical Shearlet transform to decompose noised image into many subwavelets under multiscale and multiorientation. Secondly, we gave weighted factor to those subwavelets obtained. Then, using classical Shearlet inverse transform, we obtained a composite image which is composed of those weighted subwavelets. After that, we designed fast and rough evaluation method to evaluate noise level of the new image; by using this method as fitness, we adopted PSO to find the optimal weighted factor we added; after lots of iterations, by the optimal factors and Shearlet inverse transform, we got the best denoised image. Experimental results have shown that proposed algorithm eliminates noise effectively and yields good peak signal noise ratio (PSNR.
DEFF Research Database (Denmark)
Sørensen, Rene; Lund, Erik
2013-01-01
This extended abstract presents a new parameterization for performing discrete material and thickness optimization of laminated composite structures. The parameterization is based on the work by Sørensen and Lund 2013, where we present a reformulation of the original parameterization. The reformu......This extended abstract presents a new parameterization for performing discrete material and thickness optimization of laminated composite structures. The parameterization is based on the work by Sørensen and Lund 2013, where we present a reformulation of the original parameterization....... The reformulation eliminates the need for having explicit constraint for ensuring that intermediate void does not appear in between layers of the laminate. This is achieved by utilizing a filtering technique known as a casting constraint from traditional topology optimization with isotropic materials....
Wide-field-of-view narrow-band spectral filters based on photonic crystal nanocavities.
Nakagawa, Wataru; Sun, Pang-Chen; Chen, Chyong-Hua; Fainman, Yeshaiahu
2002-02-01
We describe a novel approach to implementing wide-field-of-view narrow-band spectral filters, using an array of resonant nanocavities consisting of periodic defects in a two-dimensional three-material photonic-crystal nanostructure. We analyze the transmissivity of this type of filter for a range of wavelengths and in-plane incidence angles as a function of the defect's refractive index, the number of layers in the photonic-crystal reflectors, and the period of the defects and find that this structure diminishes the angular sensitivity of the resonance condition relative to that of a standard multilayer filter.
Li, Yifan; Liang, Xihui; Zuo, Ming J.
2017-02-01
This paper presents a novel signal processing scheme, diagonal slice spectrum assisted optimal scale morphological filter (DSS-OSMF), for rolling element fault diagnosis. In this scheme, the concept of quadratic frequency coupling (QFC) is firstly defined and the ability of diagonal slice spectrum (DSS) in detection QFC is derived. The DSS-OSMF possesses the merits of depressing noise and detecting QFC. It can remove fault independent frequency components and give a clear representation of fault symptoms. A simulated vibration signal and experimental vibration signals collected from a bearing test rig are employed to evaluate the effectiveness of the proposed method. Results show that the proposed method has a superior performance in extracting fault features of defective rolling element bearing. In addition, comparisons are performed between a multi-scale morphological filter (MMF) and a DSS-OSMF. DSS-OSMF outperforms MMF in detection of an outer race fault and a rolling element fault of a rolling element bearing.
Optimization of dichromatic filters based on photonic heterostructures of Si/MgF2
Guan, Huihuan; Han, Peide; Li, Yuping; Zhou, Hongwei; Zhang, Xue; Zhang, Ruizhen
2012-05-01
The current research work presents the theoretical results of demonstrating novel dichromatic filters, which consist of blue and yellow light. A one-dimensional photonic crystal or photonic heterostructure of Si/MgF2 is analyzed in detail by fully considering the effects of structural parameters using the transfer matrix method. The position and the number of defect modes are shown to have relationships with the repeat cycle counts of various photonic crystals. When the photonic heterostructures have the optimized structural parameters, defect modes can be obtained with high transmittances located in blue and yellow light. This photonic heterostructure is expected to be used in dichromatic filters with wide non-transmission range in a visible range.
DEFF Research Database (Denmark)
Sørensen, Rene; Lund, Erik
2015-01-01
This paper presents a new gradient based method for performing discrete material and thickness optimization of laminated composite structures. The novelty in the new method lies in the application of so-called casting constraints, or thickness filters in this context, to control the thickness...... govern the presence of material in each layer through the thickness of the laminate. Combined with an in-plane density filter, the method enables manufacturers to control the length scale of the geometry while obtaining near discrete designs. Together with the applied manufacturing constraints it is now...... possible for manufacturers to steer the design towards a higher level of manufacturability. The method is demonstrated for mass minimization with displacement and manufacturing constraints. The results show that the method indeed is capable of obtaining near discrete designs which obey the governing...
Optimal Filtering Algorithm-Based Multiuser Detector for Fast Fading CDMA Systems
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
A multiuser detector was developed for fast fading code-division multiple-access systems by representing the channels as a system with the multiplicative noise (SMN) model and then using the known optimal filtering algorithm for the SMN for multiuser detection (MUD). This multiuser detector allows the channel response to be stochastic in one symbol duration, which can be regarded as an effective method of MUD for fast fading CDMA systems. Performance analyses show that the multiuser detector is theoretically valid for CDMA systems over fast fading channels. Simulations show that the multiuser detector performs better than the Kalman filter-based multiuser detector with a faster convergence rate and lower bit error rate.
Spin Filter Effect in Organic Polymers in the Presence of Local Magnetic Field
Institute of Scientific and Technical Information of China (English)
YAN Yong-Hong; CHEN Mei-Juan; WU Chang-Qin
2006-01-01
@@ Using a nonadiabatic evolution method, we investigate the spin filter effect in organic polymers in the presence of a local magnetic field. Through a spin-dependent magnetic field, polarons (charge carrier) with different spins will feel repulsive or attractive force determined by their spins.
One-channel inverse filter: Spatio-temporal control of a complex wave-field from a single point
Rupin, Matthieu; Roux, Philippe; Catheline, Stefan
2014-06-01
Can we make good use of the degrees of freedom of a wave-field trapped in a cavity to perform complete spatio-temporal inversion from a single emitter? To answer these questions, we used experiments conducted in the ultrasonic regime to investigate the wave-field in a water cavity where the energy was not homogeneously distributed over all of the degrees of freedom. While the time reversal from a single emitter gives poor results, we show the possibility to recover optimal spatio-temporal focusing by converting the multi-channel focusing technique of the spatio-temporal inverse filter into a single-channel method that we call the one-channel inverse filter. In particular, this method has the advantage of leaving the choice open for the duration of the time window for the inversion of the wave-field. We, thus, demonstrate that the shorter the time window, the better optimized the inversion. We believe that in addition to demonstrating the possibility of controlling the waves in a cavity, this method might have an interesting role in the improvement of solid imaging devices that are based on the exploitation of reverberations in cavities.
Vandermoere, Stany; De Neve, Stefaan
2016-04-01
Flanders (Belgium) is confronted with reactive phosphorus concentrations in streams and lakes which are three to four times higher than the 0.1 ppm P limit set by the Water Framework Directive. Much of the excessive P input in surface waters is derived from agriculture. Direct P input from artificially drained fields (short-circuiting the buffering capacity of the subsoil) is suspected to be one of the major sources. We aim to develop simple and cheap filters that can be directly installed in the field to reduce P concentration from the drain water. Here we report on the performance of such filters tested at lab scale. As starting materials for the P filter, iron coated sand and acid pre-treated glauconite were used. These materials, both rich in Fe, were mixed in ratios of 75/25, 65/35, 50/50 and 0/100 (iron coated sand/glauconite ratio based on weight basis) and filled in plastic tubes. A screening experiment using the constant head method with a 0.01 M CaCl2 solution containing 1 ppm P showed that all four types of mixtures reduced the P concentration in the outflowing water to almost zero, and that the 75/25, 65/35 and 0/100 mixtures had a sufficiently large hydraulic conductivity of 0.9 to 6.0 cm/min, while the hydraulic conductivity of the 50/50 mixture was too low (CaCl2 solution containing 1 ppm P was passed through the filters over several days, in amounts equivalent to half of the yearly water volume passing through the drains. This experiment firstly showed that in all cases the hydraulic conductivity fluctuated strongly: it decreased from 4.0-6.0 cm/min to 2.0-1.5 cm/min for the 75/25 filter, and to values < 0.4 cm/min for the 65/35 filter, whereas it increased from 0.8 to 1.4 cm/min for the 0/100 filter. Secondly, we observed a decrease in the P removal efficiency with time on each day for all filters: from 90% removal to 80% removal for the 75/25 and 65/35 filters, while for the 0/100 filter the P removal almost reduced to 0%. Based on these results
Optimal IIR filter design using Gravitational Search Algorithm with Wavelet Mutation
Directory of Open Access Journals (Sweden)
S.K. Saha
2015-01-01
Full Text Available This paper presents a global heuristic search optimization technique, which is a hybridized version of the Gravitational Search Algorithm (GSA and Wavelet Mutation (WM strategy. Thus, the Gravitational Search Algorithm with Wavelet Mutation (GSAWM was adopted for the design of an 8th-order infinite impulse response (IIR filter. GSA is based on the interaction of masses situated in a small isolated world guided by the approximation of Newtonian’s laws of gravity and motion. Each mass is represented by four parameters, namely, position, active, passive and inertia mass. The position of the heaviest mass gives the near optimal solution. For better exploitation in multidimensional search spaces, the WM strategy is applied to randomly selected particles that enhance the capability of GSA for finding better near optimal solutions. An extensive simulation study of low-pass (LP, high-pass (HP, band-pass (BP and band-stop (BS IIR filters unleashes the potential of GSAWM in achieving better cut-off frequency sharpness, smaller pass band and stop band ripples, smaller transition width and higher stop band attenuation with assured stability.
Optimality analysis of one-step OOSM filtering algorithms in target tracking
Institute of Scientific and Technical Information of China (English)
ZHOU WenHui; LI Lin; CHEN GuoHai; YU AnXi
2007-01-01
In centralized multisensor tracking systems, there are out-of-sequence measurements (OOSMs) frequently arising due to different time delays in communication links and varying pre-processing times at the sensor. Such OOSM arrival can induce the "negative-time measurement update" problem, which is quite common in real multisensor tracking systems. The A1 optimal update algorithm with OOSM is presented by Bar-Shalom for one-step case. However, this paper proves that the optimality of A1 algorithm is lost in direct discrete-time model (DDM) of the process noise, it holds true only in discretized continuous-time model (DCM). One better OOSM filtering algorithm for DDM case is presented. Also, another new optimal OOSM filtering algorithm, which is independent of the discrete time model of the process noise, is presented here. The performance of the two new algorithms is compared with that of A1 algorithm by Monte Carlo simulations. The effectiveness and correctness of the two proposed algorithms are validated by analysis and simulation results.
Strahl, Stefan; Mertins, Alfred
2008-07-18
Evidence that neurosensory systems use sparse signal representations as well as improved performance of signal processing algorithms using sparse signal models raised interest in sparse signal coding in the last years. For natural audio signals like speech and environmental sounds, gammatone atoms have been derived as expansion functions that generate a nearly optimal sparse signal model (Smith, E., Lewicki, M., 2006. Efficient auditory coding. Nature 439, 978-982). Furthermore, gammatone functions are established models for the human auditory filters. Thus far, a practical application of a sparse gammatone signal model has been prevented by the fact that deriving the sparsest representation is, in general, computationally intractable. In this paper, we applied an accelerated version of the matching pursuit algorithm for gammatone dictionaries allowing real-time and large data set applications. We show that a sparse signal model in general has advantages in audio coding and that a sparse gammatone signal model encodes speech more efficiently in terms of sparseness than a sparse modified discrete cosine transform (MDCT) signal model. We also show that the optimal gammatone parameters derived for English speech do not match the human auditory filters, suggesting for signal processing applications to derive the parameters individually for each applied signal class instead of using psychometrically derived parameters. For brain research, it means that care should be taken with directly transferring findings of optimality for technical to biological systems.
Tyler, Madelaine K; Liu, Paul Z Y; Lee, Christopher; McKenzie, David R; Suchowerska, Natalka
2016-05-08
Flattening filter-free (FFF) beams are becoming the preferred beam type for stereotactic radiosurgery (SRS) and stereotactic ablative radiation therapy (SABR), as they enable an increase in dose rate and a decrease in treatment time. This work assesses the effects of the flattening filter on small field output factors for 6 MV beams generated by both Elekta and Varian linear accelerators, and determines differences between detector response in flattened (FF) and FFF beams. Relative output factors were measured with a range of detectors (diodes, ionization cham-bers, radiochromic film, and microDiamond) and referenced to the relative output factors measured with an air core fiber optic dosimeter (FOD), a scintillation dosimeter developed at Chris O'Brien Lifehouse, Sydney. Small field correction factors were generated for both FF and FFF beams. Diode measured detector response was compared with a recently published mathematical relation to predict diode response corrections in small fields. The effect of flattening filter removal on detector response was quantified using a ratio of relative detector responses in FFF and FF fields for the same field size. The removal of the flattening filter was found to have a small but measurable effect on ionization chamber response with maximum deviations of less than ± 0.9% across all field sizes measured. Solid-state detectors showed an increased dependence on the flattening filter of up to ± 1.6%. Measured diode response was within ± 1.1% of the published mathematical relation for all fields up to 30 mm, independent of linac type and presence or absence of a flattening filter. For 6 MV beams, detector correction factors between FFF and FF beams are interchangeable for a linac between FF and FFF modes, providing that an additional uncertainty of up to ± 1.6% is accepted.
Directory of Open Access Journals (Sweden)
Y. Orlov
2002-01-01
Full Text Available The paper is intended to be of tutorial value for Schwartz' distributions theory in nonlinear setting. Mathematical models are presented for nonlinear systems which admit both standard and impulsive inputs. These models are governed by differential equations in distributions whose meaning is generalized to involve nonlinear, non single-valued operating over distributions. The set of generalized solutions of these differential equations is defined via closure, in a certain topology, of the set of the conventional solutions corresponding to standard integrable inputs. The theory is exemplified by mechanical systems with impulsive phenomena, optimal impulsive feedback synthesis, sampled-data filtering of stochastic and deterministic dynamic systems.
Recovering the nonlinear density field from the galaxy distribution with a Poisson-Lognormal filter
Kitaura, Francisco S; Metcalf, R Benton
2009-01-01
We present a general expression for a lognormal filter given an arbitrary nonlinear galaxy bias. We derive this filter as the maximum a posteriori solution assuming a lognormal prior distribution for the matter field with a given mean field and modeling the observed galaxy distribution by a Poissonian process. We have performed a three-dimensional implementation of this filter with a very efficient Newton-Krylov inversion scheme. Furthermore, we have tested it with a dark matter N-body simulation assuming a unit galaxy bias relation and compared the results with previous density field estimators like the inverse weighting scheme and Wiener filtering. Our results show good agreement with the underlying dark matter field for overdensities even above delta~1000 which exceeds by one order of magnitude the regime in which the lognormal is expected to be valid. The reason is that for our filter the lognormal assumption enters as a prior distribution function, but the maximum a posteriori solution is also conditione...
Berset, Torfinn; Geng, Di; Romero, Iñaki
2012-01-01
Noise from motion artifacts is currently one of the main challenges in the field of ambulatory ECG recording. To address this problem, we propose the use of two different approaches. First, an adaptive filter with electrode-skin impedance as a reference signal is described. Secondly, a multi-channel ECG algorithm based on Independent Component Analysis is introduced. Both algorithms have been designed and further optimized for real-time work embedded in a dedicated Digital Signal Processor. We show that both algorithms improve the performance of a beat detection algorithm when applied in high noise conditions. In addition, an efficient way of choosing this methods is suggested with the aim of reduce the overall total system power consumption.
Electron cyclotron resonance heating by magnetic filter field in a negative hydrogen ion source
Energy Technology Data Exchange (ETDEWEB)
Kim, June Young, E-mail: beacoolguy@snu.ac.kr; Cho, Won-Hwi; Dang, Jeong-Jeung; Chung, Kyoung-Jae, E-mail: jkjlsh1@snu.ac.kr; Hwang, Y. S. [Department of Nuclear Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)
2016-02-15
The influence of magnetic filter field on plasma properties in the heating region has been investigated in a planar-type inductively coupled radio-frequency (RF) H{sup −} ion source. Besides filtering high energy electrons near the extraction region, the magnetic filter field is clearly observed to increase the electron temperature in the heating region at low pressure discharge. With increasing the operating pressure, enhancement of electron temperature in the heating region is reduced. The possibility of electron cyclotron resonance (ECR) heating in the heating region due to stray magnetic field generated by a filter magnet located at the extraction region is examined. It is found that ECR heating by RF wave field in the discharge region, where the strength of an axial magnetic field is approximately ∼4.8 G, can effectively heat low energy electrons. Depletion of low energy electrons in the electron energy distribution function measured at the heating region supports the occurrence of ECR heating. The present study suggests that addition of axial magnetic field as small as several G by an external electromagnet or permanent magnets can greatly increase the generation of highly ro-vibrationally excited hydrogen molecules in the heating region, thus improving the performance of H{sup −} ion generation in volume-produced negative hydrogen ion sources.
Optimal sampling schemes for vegetation and geological field visits
CSIR Research Space (South Africa)
Debba, Pravesh
2012-07-01
Full Text Available The presentation made to Wits Statistics Department was on common classification methods used in the field of remote sensing, and the use of remote sensing to design optimal sampling schemes for field visits with applications in vegetation...
Point source detection and extraction from simulated Planck TOD using optimal adaptive filters
Herranz, D; Sanz, J L; Martínez-González, E
2002-01-01
Wavelet-related techniques have proven useful in the processing and analysis of one and two dimensional data sets (spectra in the former case, images in the latter). In this work we apply adaptive filters, introduced in a previous work (Sanz et al. 2001), to optimize the detection and extraction of point sources from a one-dimensional array of time-ordered data such as the one that will be produced by the future 30 GHz LFI28 channel of the ESA Planck mission. At a $4\\sigma$ detection level 224 sources over a flux of 0.88 Jy are detected with a mean relative error (in absolute value) of 21% and a systematic bias of -7.7%. The position of the sources in the sky is determined with errors inferior to the size of the pixel. The catalogue of detected sources is complete at fluxes $\\geq$ 4.3 Jy. The number of spurious detections is less than a 10% of the true detections. We compared the results with the ones obtained by filtering with a Gaussian filter and a Mexican Hat Wavelet of width equal to the scale of the sou...
Denève, Sophie; Duhamel, Jean-René; Pouget, Alexandre
2007-05-23
Several behavioral experiments suggest that the nervous system uses an internal model of the dynamics of the body to implement a close approximation to a Kalman filter. This filter can be used to perform a variety of tasks nearly optimally, such as predicting the sensory consequence of motor action, integrating sensory and body posture signals, and computing motor commands. We propose that the neural implementation of this Kalman filter involves recurrent basis function networks with attractor dynamics, a kind of architecture that can be readily mapped onto cortical circuits. In such networks, the tuning curves to variables such as arm velocity are remarkably noninvariant in the sense that the amplitude and width of the tuning curves of a given neuron can vary greatly depending on other variables such as the position of the arm or the reliability of the sensory feedback. This property could explain some puzzling properties of tuning curves in the motor and premotor cortex, and it leads to several new predictions.
Multiplier-free filters for wideband SAR
DEFF Research Database (Denmark)
Dall, Jørgen; Christensen, Erik Lintz
2001-01-01
This paper derives a set of parameters to be optimized when designing filters for digital demodulation and range prefiltering in SAR systems. Aiming at an implementation in field programmable gate arrays (FPGAs), an approach for the design of multiplier-free filters is outlined. Design results ar...... are presented in terms of filter complexity and performance. One filter has been coded in VHDL and preliminary results indicate that the filter can meet a 2 GHz input sample rate....
Designing optimal sampling schemes for field visits
CSIR Research Space (South Africa)
Debba, Pravesh
2008-10-01
Full Text Available This is a presentation of a statistical method for deriving optimal spatial sampling schemes. The research focuses on ground verification of minerals derived from hyperspectral data. Spectral angle mapper (SAM) and spectral feature fitting (SFF...
Field sampling scheme optimization using simulated annealing
CSIR Research Space (South Africa)
Debba, Pravesh
2010-10-01
Full Text Available to derive optimal sampling schemes. 2. Hyperspectral remote sensing In the study of electro-magnetic physics, when energy in the form of light interacts with a material, part of the energy at certain wavelength is absorbed, transmitted, emitted... in order to derive optimal sampling schemes. 2. Hyperspectral remote sensing In the study of electro-magnetic physics, when energy in the form of light interacts with a material, part of the energy at certain wavelength is absorbed, transmitted, emitted...
Field investigation of arsenic in ceramic pot filter-treated drinking water.
Archer, A R; Elmore, A C; Bell, E; Rozycki, C
2011-01-01
Ceramic pot filters (CPFs) is one of several household water treatment technologies that is used to treat drinking water in developing areas. The filters have the advantage of being able to be manufactured using primarily locally available materials and local labor. However, naturally-occurring arsenic present in the clay used to make the filters has the potential to contaminate the water in excess of the World Health Organization drinking water standard of 0.01 mg/L. A manufacturing facility in Guatemala routinely rinses filters to reduce arsenic concentrations prior to distribution to consumers. A systemic study was performed to evaluate the change in arsenic concentrations with increasing volumes of rinse water. Arsenic field kit results were compared to standard method laboratory results, and dissolved versus suspended arsenic concentrations in CPF-treated water were evaluated. The results of the study suggest that rinsing is an effective means of mitigating arsenic leached from the filters, and that even in the absence of a formal rinsing program, routine consumer use may result in the rapid decline of arsenic concentrations. More importantly, the results indicate that filter manufacturers should give strong consideration to implementing an arsenic testing program.
Directory of Open Access Journals (Sweden)
M. Kumar
2016-01-01
Full Text Available Gaussian noise is one of the dominant noises, which degrades the quality of acquired Computed Tomography (CT image data. It creates difficulties in pathological identification or diagnosis of any disease. Gaussian noise elimination is desirable to improve the clarity of a CT image for clinical, diagnostic, and postprocessing applications. This paper proposes an evolutionary nonlinear adaptive filter approach, using Cat Swarm Functional Link Artificial Neural Network (CS-FLANN to remove the unwanted noise. The structure of the proposed filter is based on the Functional Link Artificial Neural Network (FLANN and the Cat Swarm Optimization (CSO is utilized for the selection of optimum weight of the neural network filter. The applied filter has been compared with the existing linear filters, like the mean filter and the adaptive Wiener filter. The performance indices, such as peak signal to noise ratio (PSNR, have been computed for the quantitative analysis of the proposed filter. The experimental evaluation established the superiority of the proposed filtering technique over existing methods.
Hydrodynamic studies of gas objects of the Shurtan field with nonstationary filtering regimes
Energy Technology Data Exchange (ETDEWEB)
Zhumayev, Kh.B.; Abayev, M.Kh.
1978-01-01
In the prospecting and exploratory wells of west and south Uzbekistan, hydrodynamic studies of the influx of gas and oil during their testing were made with stationary filtering regimes. Analysis of results of the well studies with stationary and nonstationary filtering regimes made it possible to reveal greater information content of the latter. Results are compared of hydrodynamic studies on both filtering regimes in the example of the gas-condensate field Shurtan. A technique is presented for the studies. The results were processed according to ''Instructions for Studying Gas Wells.'' In order to compare the results of hydrodynamic studies, the coefficience of filtering resistance A and V were defined, the absolutely free output of wells and the coefficient of hydraulic conductance of bed Ye. Data are presented in a table and are analyzed. It is indicated that by making hydrodynamic studies with nonstationary filtering regimes of gas, one can obtain the most important data regarding the hydrodynamic condition of the gas formations, and reduce the periods for well testing. The economic effect is calculated and recommendations are made for studying the fields.
Quantum Master Equation and Filter for Systems Driven by Fields in a Single Photon State
Gough, J E; Nurdin, H I
2011-01-01
The aim of this paper is to determine quantum master and filter equations for systems coupled to continuous-mode single photon fields. The system and field are described using a quantum stochastic unitary model, where the continuous-mode single photon state for the field is determined by a wavepacket pulse shape. The master equation is derived from this model and is given in terms of a system of coupled equations. The output field carries information about the system from the scattered photon, and is continuously monitored. The quantum filter is determined with the aid of an embedding of the system into a larger system, and is given by a system of coupled stochastic differential equations. An example is provided to illustrate the main results.
Niederhauser, Thomas; Wyss-Balmer, Thomas; Haeberlin, Andreas; Marisa, Thanks; Wildhaber, Reto A; Goette, Josef; Jacomet, Marcel; Vogel, Rolf
2015-06-01
Long-term electrocardiogram (ECG) often suffers from relevant noise. Baseline wander in particular is pronounced in ECG recordings using dry or esophageal electrodes, which are dedicated for prolonged registration. While analog high-pass filters introduce phase distortions, reliable offline filtering of the baseline wander implies a computational burden that has to be put in relation to the increase in signal-to-baseline ratio (SBR). Here, we present a graphics processor unit (GPU)-based parallelization method to speed up offline baseline wander filter algorithms, namely the wavelet, finite, and infinite impulse response, moving mean, and moving median filter. Individual filter parameters were optimized with respect to the SBR increase based on ECGs from the Physionet database superimposed to autoregressive modeled, real baseline wander. A Monte-Carlo simulation showed that for low input SBR the moving median filter outperforms any other method but negatively affects ECG wave detection. In contrast, the infinite impulse response filter is preferred in case of high input SBR. However, the parallelized wavelet filter is processed 500 and four times faster than these two algorithms on the GPU, respectively, and offers superior baseline wander suppression in low SBR situations. Using a signal segment of 64 mega samples that is filtered as entire unit, wavelet filtering of a seven-day high-resolution ECG is computed within less than 3 s. Taking the high filtering speed into account, the GPU wavelet filter is the most efficient method to remove baseline wander present in long-term ECGs, with which computational burden can be strongly reduced.
Optimal Moments for Velocity Fields Analysis
Feldman, H A; Melott, A; Feldman, Hume A; Watkins, Richard; Melott, Adrian; Proxy, Will Chambers; ccsd-00000954, ccsd
2003-01-01
We describe a new method of overcoming problems inherent in peculiar velocity surveys by using data compression as a filter with which to separate large-scale, linear flows from small-scale noise that biases the results systematically. We demonstrate the effectiveness of our method using realistic catalogs of galaxy velocities drawn from N--body simulations. Our tests show that a likelihood analysis of simulated catalogs that uses all of the information contained in the peculiar velocities results in a bias in the estimation of the power spectrum shape parameter $\\Gamma$ and amplitude $\\beta$, and that our method of analysis effectively removes this bias. We expect that this new method will cause peculiar velocity surveys to re--emerge as a useful tool to determine cosmological parameters.
Bifurcations of optimal vector fields: an overview
Kiseleva, T.; Wagener, F.; Rodellar, J.; Reithmeier, E.
2009-01-01
We develop a bifurcation theory for the solution structure of infinite horizon optimal control problems with one state variable. It turns out that qualitative changes of this structure are connected to local and global bifurcations in the state-costate system. We apply the theory to investigate an
Mazzà, Claudia; Donati, Marco; McCamley, John; Picerno, Pietro; Cappozzo, Aurelio
2012-01-01
The aim of this study was the fine tuning of a Kalman filter with the intent to provide optimal estimates of lower trunk orientation in the frontal and sagittal planes during treadmill walking at different speeds using measured linear acceleration and angular velocity components represented in a local system of reference. Data were simultaneously collected using both an inertial measurement unit (IMU) and a stereophotogrammetric system from three healthy subjects walking on a treadmill at natural, slow and fast speeds. These data were used to estimate the parameters of the Kalman filter that minimized the difference between the trunk orientations provided by the filter and those obtained through stereophotogrammetry. The optimized parameters were then used to process the data collected from a further 15 healthy subjects of both genders and different anthropometry performing the same walking tasks with the aim of determining the robustness of the filter set up. The filter proved to be very robust. The root mean square values of the differences between the angles estimated through the IMU and through stereophotogrammetry were lower than 1.0° and the correlation coefficients between the corresponding curves were greater than 0.91. The proposed filter design can be used to reliably estimate trunk lateral and frontal bending during walking from inertial sensor data. Further studies are needed to determine the filter parameters that are most suitable for other motor tasks.
Design and optimization of an analog filter with a CdTe detector for X-ray fluorescence applications
Choi, Hyojeong; Kim, Hui Su; Kim, Young Soo; Ha, Jang Ho; Chai, Jong-Seo
2016-10-01
An analog pre-filter circuit for digital pulse processing is designed and optimized for X-ray fluorescence (XRF) applications to replace traditional analog shaping amplifiers. To optimize the pre-filter performance, we characterized noise electrons as a function of the input pulse rise time and decay time of the output pulse by using the full width at half maximum. In addition, gamma-ray energy measurements at room temperature showed that the commercially available CdTe Schottky-type radiation detector with our newly designed and optimized pre-filter circuit exhibited full widths at half maxima of 4.97 (Ba-133, at 53 keV) and 5.56 keV (Am-241, at 59.5 keV), respectively.
Chen, Jie; Li, Jiahong; Yang, Shuanghua; Deng, Fang
2016-07-21
The identification of the nonlinearity and coupling is crucial in nonlinear target tracking problem in collaborative sensor networks. According to the adaptive Kalman filtering (KF) method, the nonlinearity and coupling can be regarded as the model noise covariance, and estimated by minimizing the innovation or residual errors of the states. However, the method requires large time window of data to achieve reliable covariance measurement, making it impractical for nonlinear systems which are rapidly changing. To deal with the problem, a weighted optimization-based distributed KF algorithm (WODKF) is proposed in this paper. The algorithm enlarges the data size of each sensor by the received measurements and state estimates from its connected sensors instead of the time window. A new cost function is set as the weighted sum of the bias and oscillation of the state to estimate the "best" estimate of the model noise covariance. The bias and oscillation of the state of each sensor are estimated by polynomial fitting a time window of state estimates and measurements of the sensor and its neighbors weighted by the measurement noise covariance. The best estimate of the model noise covariance is computed by minimizing the weighted cost function using the exhaustive method. The sensor selection method is in addition to the algorithm to decrease the computation load of the filter and increase the scalability of the sensor network. The existence, suboptimality and stability analysis of the algorithm are given. The local probability data association method is used in the proposed algorithm for the multitarget tracking case. The algorithm is demonstrated in simulations on tracking examples for a random signal, one nonlinear target, and four nonlinear targets. Results show the feasibility and superiority of WODKF against other filtering algorithms for a large class of systems.
Application of digital tomosynthesis (DTS) of optimal deblurring filters for dental X-ray imaging
Energy Technology Data Exchange (ETDEWEB)
Oh, J. E.; Cho, H. S.; Kim, D. S.; Choi, S. I.; Je, U. K. [Yonsei University, Wonju (Korea, Republic of)
2012-04-15
Digital tomosynthesis (DTS) is a limited-angle tomographic technique that provides some of the tomographic benefits of computed tomography (CT) but at reduced dose and cost. Thus, the potential for application of DTS to dental X-ray imaging seems promising. As a continuation of our dental radiography R and D, we developed an effective DTS reconstruction algorithm and implemented it in conjunction with a commercial dental CT system for potential use in dental implant placement. The reconstruction algorithm employed a backprojection filtering (BPF) method based upon optimal deblurring filters to suppress effectively both the blur artifacts originating from the out-focus planes and the high-frequency noise. To verify the usefulness of the reconstruction algorithm, we performed systematic simulation works and evaluated the image characteristics. We also performed experimental works in which DTS images of enhanced anatomical resolution were successfully obtained by using the algorithm and were promising to our ongoing applications to dental X-ray imaging. In this paper, our approach to the development of the DTS reconstruction algorithm and the results are described in detail.
Spatio-spectral color filter array design for optimal image recovery.
Hirakawa, Keigo; Wolfe, Patrick J
2008-10-01
In digital imaging applications, data are typically obtained via a spatial subsampling procedure implemented as a color filter array-a physical construction whereby only a single color value is measured at each pixel location. Owing to the growing ubiquity of color imaging and display devices, much recent work has focused on the implications of such arrays for subsequent digital processing, including in particular the canonical demosaicking task of reconstructing a full color image from spatially subsampled and incomplete color data acquired under a particular choice of array pattern. In contrast to the majority of the demosaicking literature, we consider here the problem of color filter array design and its implications for spatial reconstruction quality. We pose this problem formally as one of simultaneously maximizing the spectral radii of luminance and chrominance channels subject to perfect reconstruction, and-after proving sub-optimality of a wide class of existing array patterns-provide a constructive method for its solution that yields robust, new panchromatic designs implementable as subtractive colors. Empirical evaluations on multiple color image test sets support our theoretical results, and indicate the potential of these patterns to increase spatial resolution for fixed sensor size, and to contribute to improved reconstruction fidelity as well as significantly reduced hardware complexity.
Classification of high spatial resolution imagery using optimal Gabor-filters-based texture features
Zhao, Yindi; Wu, Bo
2007-06-01
Texture analysis has received great attention in the interpretation of high-resolution satellite images. This paper aims to find optimal filters for discriminating between residential areas and other land cover types in high spatial resolution satellite imagery. Moreover, in order to reduce the blurring border effect, inherent in texture analysis and which introduces important errors in the transition areas between different texture units, a classification procedure is designed for such high spatial resolution satellite images as follows. Firstly, residential areas are detected using Gabor texture features, and two clusters, one a residential area and the other not, are detected using the fuzzy C-Means algorithm, in the frequency space based on Gabor filters. Sequentially, a mask is generated to eliminate residential areas so that other land-cover types would be classified accurately, and not interfered with the spectrally heterogeneous residential areas. Afterwards, other objects are classified using spectral features by the MAP (maximum a posterior) - ICM (iterated conditional mode) classification algorithm designed to enforce the spatial constraints into classification. Experimental results on high spatial resolution remote sensing data confirm that the proposed algorithm provide remarkably better detection accuracy than conventional approaches in terms of both objective measurements and visual evaluation.
Bedard, C; Destexhe, A; Bédard, Claude; Kroeger, Helmut; Destexhe, Alain
2003-01-01
Extracellular local field potentials (LFP) are usually modeled as arising from a set of current sources embedded in a homogeneous extracellular medium. Although this formalism can successfully model several properties of LFPs, it does not account for their frequency-dependent attenuation with distance, a property essential to correctly model extracellular spikes. Here we derive expressions for the extracellular potential that include this frequency-dependent attenuation. We first show that, if the extracellular conductivity is non-homogeneous, there is induction of non-homogeneous charge densities which may result in a low-pass filter. We next derive a simplified model consisting of a punctual (or spherical) current source with spherically-symmetric conductivity/permittivity gradients around the source. We analyze the effect of different radial profiles of conductivity and permittivity on the frequency-filtering behavior of this model. We show that this simple model generally displays low-pass filtering behav...
NON-SCALING FIXED FIELD GRADIENT OPTIMIZATION.
Energy Technology Data Exchange (ETDEWEB)
TRBOJEVIC, D.
2004-10-13
Optimization of the non-scaling FFAG lattice for the specific application of the muon acceleration with respect to the minimum orbit offsets, minimum path length and smallest circumference is described. The short muon lifetime requires fast acceleration. The acceleration is in this work assumed to be with super-conducting cavities. This sets up a condition of acceleration at the top of the sinusoidal RF wave.
Extragalactic Fields Optimized for Adaptive Optics
2011-03-01
DAVID MONETIO Received 2010 luly 19; accepted 2010 December 30; published 2011 March 1 ABSTRACT. In this article we present the coordinates of 67 55’ x...fields. In some cases adaptive optics observations undertaken in the fields given in this article would be orders of magnitude more efficient than...expectations of considerable pro- gress in this subject with the advent of 30 m class extremely large telescopes ( ELTs ). A basic problem with unde1taking
Panigrahi, Swapnesh; Ramachandran, Hema; Alouini, Mehdi
2016-01-01
The efficiency of using intensity modulated light for estimation of scattering properties of a turbid medium and for ballistic photon discrimination is theoretically quantified in this article. Using the diffusion model for modulated photon transport and considering a noisy quadrature demodulation scheme, the minimum-variance bounds on estimation of parameters of interest are analytically derived and analyzed. The existence of a variance-minimizing optimal modulation frequency is shown and its evolution with the properties of the intervening medium is derived and studied. Furthermore, a metric is defined to quantify the efficiency of ballistic photon filtering which may be sought when imaging through turbid media. The analytical derivation of this metric shows that the minimum modulation frequency required to attain significant ballistic discrimination depends only on the reduced scattering coefficient of the medium in a linear fashion for a highly scattering medium.
Panigrahi, Swapnesh; Fade, Julien; Ramachandran, Hema; Alouini, Mehdi
2016-07-11
The efficiency of using intensity modulated light for the estimation of scattering properties of a turbid medium and for ballistic photon discrimination is theoretically quantified in this article. Using the diffusion model for modulated photon transport and considering a noisy quadrature demodulation scheme, the minimum-variance bounds on estimation of parameters of interest are analytically derived and analyzed. The existence of a variance-minimizing optimal modulation frequency is shown and its evolution with the properties of the intervening medium is derived and studied. Furthermore, a metric is defined to quantify the efficiency of ballistic photon filtering which may be sought when imaging through turbid media. The analytical derivation of this metric shows that the minimum modulation frequency required to attain significant ballistic discrimination depends only on the reduced scattering coefficient of the medium in a linear fashion for a highly scattering medium.
New efficient optimizing techniques for Kalman filters and numerical weather prediction models
Famelis, Ioannis; Galanis, George; Liakatas, Aristotelis
2016-06-01
The need for accurate local environmental predictions and simulations beyond the classical meteorological forecasts are increasing the last years due to the great number of applications that are directly or not affected: renewable energy resource assessment, natural hazards early warning systems, global warming and questions on the climate change can be listed among them. Within this framework the utilization of numerical weather and wave prediction systems in conjunction with advanced statistical techniques that support the elimination of the model bias and the reduction of the error variability may successfully address the above issues. In the present work, new optimization methods are studied and tested in selected areas of Greece where the use of renewable energy sources is of critical. The added value of the proposed work is due to the solid mathematical background adopted making use of Information Geometry and Statistical techniques, new versions of Kalman filters and state of the art numerical analysis tools.
Kalman Filtered Daily GRACE Gravity Field Solutions in Near Real-Time- First Steps
Kvas, Andreas; Mayer-Gurr, Torsten
2016-08-01
As part of the EGSIEM (European Gravity Service for Improved Emergency Management) project, a technology demonstrator for a near real-time (NRT) gravity field service will be established. In preparation of the operational phase, several aspects of the daily gravity field processing chain at Graz University of Technology have been inspected in order to improve the gravity field solutions and move towards NRT. The effect of these adaptions is investigated by comparison with post-processing and forward-only filtered solutions and evaluated using in-situ data.
Liu, Dong; Hostetler, Chris; Cook, Anthony; Miller, Ian; Hair, Johnathan
2011-11-01
High spectral resolution lidars (HSRLs) are increasingly being deployed on aircraft and called for on future space-based missions. The HSRL technique relies on spectral discrimination of the atmospheric backscatter signals to enable independent, unambiguous retrieval of aerosol extinction and backscatter. A compact, monolithic field-widened Michelson interferometer is being developed as the spectral discrimination filter for an HSRL system at NASA Langley Research Center. The interferometer consists of a cubic beam splitter, a solid glass arm, and an air arm. The spacer that connects the air arm mirror to the main part of the interferometer is designed to optimize thermal compensation such that the maximum interference can be tuned with great precision to the transmitted laser wavelength. In this paper, a comprehensive radiometric model for the field-widened Michelson interferometeric spectral filter is presented. The model incorporates the angular distribution and finite cross sectional area of the light source, reflectance of all surfaces, loss of absorption, and lack of parallelism between the air-arm and solid arm, etc. The model can be used to assess the performance of the interferometer and thus it is a useful tool to evaluate performance budgets and to set optical specifications for new designs of the same basic interferometer type.
Delay Kalman Filter to Estimate the Attitude of a Mobile Object with Indoor Magnetic Field Gradients
Directory of Open Access Journals (Sweden)
Christophe Combettes
2016-05-01
Full Text Available More and more services are based on knowing the location of pedestrians equipped with connected objects (smartphones, smartwatches, etc.. One part of the location estimation process is attitude estimation. Many algorithms have been proposed but they principally target open space areas where the local magnetic field equals the Earth’s field. Unfortunately, this approach is impossible indoors, where the use of magnetometer arrays or magnetic field gradients has been proposed. However, current approaches omit the impact of past state estimates on the current orientation estimate, especially when a reference field is computed over a sliding window. A novel Delay Kalman filter is proposed in this paper to integrate this time correlation: the Delay MAGYQ. Experimental assessment, conducted in a motion lab with a handheld inertial and magnetic mobile unit, shows that the novel filter better estimates the Euler angles of the handheld device with an 11.7° mean error on the yaw angle as compared to 16.4° with a common Additive Extended Kalman filter.
Directory of Open Access Journals (Sweden)
Ahmed M. Othman
2017-06-01
Full Text Available This paper presents a design of microgrid (MG with enhanced dynamic performance. Distributed energy resources (DER are widely used in MGs to match the various load types and profiles. DERs include solar PV cells, wind energy sources, fuel cells, batteries, micro gas-engines and storage elements. MG will include AC/DC circuits, developed power electronics devices, inverters and power electronic controllers. A novel modulated power filters (MPF device will be applied in MG design. Enhanced bacterial foraging optimization (EBFO will be proposed to optimize and set the MPF parameters to enhance and tune the MG dynamic response. Recent dynamic control is applied to minimize the harmonic reference content. EBFO will adapt the gains of MPF dynamic control. The present research achieves an enhancement of MG dynamic performance, in addition to ensuring improvements in the power factor, bus voltage profile and power quality. MG operation will be evaluated by the dynamic response to be fine-tuned by MPF based on EBFO. Digital simulations have validated the results to show the effectiveness and efficient improvement by the proposed strategy.
Directory of Open Access Journals (Sweden)
Siddhartha Mukherjee
2014-04-01
Full Text Available This paper gives a detailed study on the performance of image filter algorithm with various parameters applied on an image of RGB model. There are various popular image filters, which consumes large amount of computing resources for processing. Oil paint image filter is one of the very interesting filters, which is very performance hungry. Current research tries to find improvement in oil paint image filter algorithm by using parallel pattern library. With increasing kernel-size, the processing time of oil paint image filter algorithm increases exponentially. I have also observed in various blogs and forums, the questions for faster oil paint have been asked repeatedly.
Four optimal design approaches of high-order finite-impulse response filters based on neural network
Institute of Scientific and Technical Information of China (English)
WANG Xiao-hua; HE Yi-gang; LIU Mei-rong
2007-01-01
Four optimal approaches of high-order finite-impulse response(FIR)digital filters were developed for designing four types filters using neural network algorithms. The solutions were presented as parallel algorithms to approximate the desired frequency response specification.Therefore, these methods avoid matrix inversion, and make a fast calculation of the filter's coeffcients possible.The convergence theorems of these proposed algorithms were presented and proved to illustrate them stable, and the implementation of these methods was described together with some design guidelines.The simulation results show that the ripples of the designed FIR filters are significantly little in the pass.band and stop-band, and the proposed algorithms are of fast convergence.
Phase optimization problems applications in wave field theory
Bulatsyk, Olena O; Topolyuk, Yury P; Bulatsyk, Olena; Voitovich, Nikolai N
2010-01-01
This is the only book available in English language to consider inverse and optimization problems in which phase field distributions are used as optimizing functions. The mathematical technique used relates to nonlinear integral equations, with numerical methods developed and applied to concrete problems. Written by a team of outstanding and renowned experts in the field, this monograph will appeal to all those dealing with the investigation, design, and optimization of electromagnetic and acoustic radiating and transmitting devices and systems, while also being of interest to mathematicians w
Modeling of the subgrid-scale term of the filtered magnetic field transport equation
Balarac, Guillaume; Kosovichev, Alexander; Brugière, Olivier; Wray, Alan; Mansour, Nagi
2010-01-01
Accurate subgrid-scale turbulence models are needed to perform realistic numerical magnetohydrodynamic (MHD) simulations of the subsurface flows of the Sun. To perform large-eddy simulations (LES) of turbulent MHD flows, three unknown terms have to be modeled. As a first step, this work proposes to use a priori tests to measure the accuracy of various models proposed to predict the SGS term appearing in the transport equation of the filtered magnetic field. It is proposed to evaluate the SGS ...
Maj, Jean-Baptiste; Royackers, Liesbeth; Moonen, Marc; Wouters, Jan
2005-09-01
In this paper, the first real-time implementation and perceptual evaluation of a singular value decomposition (SVD)-based optimal filtering technique for noise reduction in a dual microphone behind-the-ear (BTE) hearing aid is presented. This evaluation was carried out for a speech weighted noise and multitalker babble, for single and multiple jammer sound source scenarios. Two basic microphone configurations in the hearing aid were used. The SVD-based optimal filtering technique was compared against an adaptive beamformer, which is known to give significant improvements in speech intelligibility in noisy environment. The optimal filtering technique works without assumptions about a speaker position, unlike the two-stage adaptive beamformer. However this strategy needs a robust voice activity detector (VAD). A method to improve the performance of the VAD was presented and evaluated physically. By connecting the VAD to the output of the noise reduction algorithms, a good discrimination between the speech-and-noise periods and the noise-only periods of the signals was obtained. The perceptual experiments demonstrated that the SVD-based optimal filtering technique could perform as well as the adaptive beamformer in a single noise source scenario, i.e., the ideal scenario for the latter technique, and could outperform the adaptive beamformer in multiple noise source scenarios.
DEFF Research Database (Denmark)
Saridakis, Stefanos; Koutroulis, Eftichios; Blaabjerg, Frede
2013-01-01
Single-phase transformerless Photovoltaic (PV) inverters are synthesized by combining available solutions in terms of the power section topology, power semiconductors manufacturing technology and structure of the output filter. A design method is presented in this paper for optimizing the power s...
DEFF Research Database (Denmark)
Zhou, Dao; Blaabjerg, Frede; Franke, Toke
2015-01-01
through the rotor-side converter or the grid-side converter. This paper first compares the current ripples and supportive reactive power ranges between the conventional L and optimized LCL filter, if the reactive power is injected from the grid-side converter. Then, the loss distribution is evaluated both...
DEFF Research Database (Denmark)
Zhou, Dao; Blaabjerg, Frede; Franke, Toke
2014-01-01
the rotor-side converter or the grid-side converter. This paper firstly compares the current ripples and supportive reactive power ranges between the conventional L and optimized LCL filter, if the reactive power is injected from the grid-side converter. Then, the loss distribution is evaluated both...
THE INVERSE PROBLEM OF OPTIMAL ONESTEP AND MULTI-STEP FILTERING OF MEASUREMENT ERRORS IN THE VECTOR
Directory of Open Access Journals (Sweden)
Laipanova Z. M.
2015-12-01
Full Text Available In practice, we often encounter the problem of determining a system state based on results of various measurements. Measurements are usually accompanied by random errors; therefore, we should not talk about the definition of the system state but its estimation through stochastic processing of measurement results. In the monograph by E. A. Semenchina and M. Z. Laipanova [1] it was investigated for one-step filtering of the measurement errors of the vector of demand in balance model of Leontiev, as well as multistage optimal filtering of measurement errors of the vector of demand. In this article, we have delivered and investigated the inverse problem for the optimal one-step and multi-step filtering of the measurement errors of the vector of demand. For its solution, the authors propose the method of conditional optimization and using given and known disturbance to determine (estimate the matrix elements for one-step filtering of measurement errors and for multi-stage filtration: for given variables and known disturbance to determine the elements of the matrix. The solution of the inverse problem is reduced to the solution of constrained optimization problems, which is easily determined using in MS Excel. The results of the research have been outlined in this article, they are of considerable interest in applied researches. The article also formulated and the proposed method of solution of inverse in a dynamic Leontiev model
Propagating adaptive-weighted vector median filter for motion-field smoothing
Institute of Scientific and Technical Information of China (English)
林梦冬; 余松煜
2004-01-01
In the field of predictive video coding and format conversion, there is an increasing attention towards estimation of the true inter-frame motion. The restoration of motion vector field computed by 3-D RS is addressed and a propagating adaptive-weighted vector median (PAWVM) post-filter is proposed. This approach decomposes blocks to make a betteres timation on object borders and propagates good vectors in the scanning direction. Furthermore, a hard-thresholding method is introduced into calculating vector weights to improve the propagating. By exploiting both the spatial correlation of the vector field and the matching error of candidate vectors, PAWVM makes a good balance between the smoothness of vector field and the prediction error, and the output vector field is more valid to reflect the true motion.
Water Modeling of Optimizing Tundish Flow Field
Institute of Scientific and Technical Information of China (English)
LIU Jin-gang; YAN Hui-cheng; LIU Liu; WANG Xin-hua
2007-01-01
In the water modeling experiments, three cases were considered, i.e. , a bare tundish, a tundish equipped with a turbulence inhibitor, and a rectangular tundish equipped with weirs (dams) and a turbulence inhibitor. Comparing the RTD curves, inclusion separation, and the result of the streamline experiment, it can be found that the tundish equipped with weirs (dams) and a turbulence inhibitor has a great effect on the flow field and the inclusion separation when compared with the sole use or no use of the turbulent inhibitor or weirs (dams). In addition, the enlargement of the distance between the weir and dam will result in a better effect when the tundish equipped with weirs (dam) and a turbulence inhibitor was used.
Directory of Open Access Journals (Sweden)
A. Konstantaras
2006-01-01
Full Text Available The method of Hybrid Adaptive Filtering (HAF aims to recover the recorded electric field signals from anomalies of magnetotelluric origin induced mainly by magnetic storms. An adaptive filter incorporating neuro-fuzzy technology has been developed to remove any significant distortions from the equivalent magnetic field signal, as retrieved from the original electric field signal by reversing the magnetotelluric method. Testing with further unseen data verifies the reliability of the model and demonstrates the effectiveness of the HAF method.
The Optimized Design of Filter by Interactive Simulation in ADS%ADS交互仿真优化滤波器设计
Institute of Scientific and Technical Information of China (English)
郭勇
2012-01-01
The optimized design of filter is the key and difficult points in designing. This paper introduces a method named interactive simulation between circuits and electromagnetic fields, and then gives the detailed steps with an example of microstrip wideband bandpass filter. At last, the effective result is demonstrated.%滤波器的优化仿真是设计的重点和难点。针对此，应用ADS软件，介绍了一种电路和电磁场之间的交互联合仿真，结合微带带通滤波器实例给出了详细的步骤，并得到了有效的结果。
An evaluation of artifact SO 42- formation on nylon filters under field conditions
Chan, Walter H.; Orr, Daniel B.; Chung, David H. S.
The extent of SO 2 conversion on Membrana (Ghia) Nylasorb nylon filters under field conditions has been evaluated and found to be quite variable. The S-SO 42- loading on the nylon filters is higher at higher SO 2 concentrations, and on a long term basis approaches a saturatio limit of 2.5 μg S-SO 42- on a 47mm disc, at a dosage of 230 μg SO 2 approximately. The % conversion decreases as the SO 2 concentration increases. On a long term basis, at an SO 2 concentration range of 1.0-7.7 μg m -3, the conversion ranges from 8.2% to 2.1%. The dependence of SO 2 conversion on nylon filters on relative humidity displays a diurnal pattern. An expression has been derived to explain the observed % SO 2 conversion on nylon filters as a combined effect of the ambient SO 2 concentration and relative humidity.
Second-Order Cone Formulations of Mixed-Norm Error Constraints for FIR Filter Optimization
2010-06-25
length N an approximate rule of thumb for the minimum grid spacing is 1/(20N). If E is a real-valued function, representing a linear- phase filter , then...well as the general Lp solution. The filter has 35 real coefficients with no symmetry and a reduced passband delay (relative to a linear phase filter ) of
Using remotely-sensed data for optimal field sampling
CSIR Research Space (South Africa)
Debba, Pravesh
2008-09-01
Full Text Available to carry out a fieldwork sample is an important issue as it avoids subjective judgement and can save on time and costs in the field. STATISTICAL SAMPLING, USING DATA OBTAINED FROM REMOTE SENSING, FINDS APPLICATION IN A VARIETY OF FIELDS... M B E R 2 0 0 8 15 USING REMOTELY- SENSED DATA FOR OPTIMAL FIELD SAMPLING BY DR PRAVESH DEBBA STATISTICS IS THE SCIENCE pertaining to the collection, summary, analysis, interpretation and presentation of data. It is often impractical...
Heliostat field cost reduction by `slope drive' optimization
Arbes, Florian; Weinrebe, Gerhard; Wöhrbach, Markus
2016-05-01
An algorithm to optimize power tower heliostat fields employing heliostats with so-called slope drives is presented. It is shown that a field using heliostats with the slope drive axes configuration has the same performance as a field with conventional azimuth-elevation tracking heliostats. Even though heliostats with the slope drive configuration have a limited tracking range, field groups of heliostats with different axes or different drives are not needed for different positions in the heliostat field. The impacts of selected parameters on a benchmark power plant (PS10 near Seville, Spain) are analyzed.
A Dedicated Inferior Vena Cava Filter Service Line: How to Optimize Your Practice.
Karp, Jennifer K; Desai, Kush R; Salem, Riad; Ryu, Robert K; Lewandowski, Robert J
2016-06-01
Despite the increased placement of retrievable inferior vena cava filters (rIVCFs), efforts to remove these devices are not commensurate. The majority of rIVCFs are left in place beyond their indicated usage, and often are retained permanently. With a growing understanding of the clinical issues associated with these devices, the United States Food and Drug Administration (FDA) has prompted clinicians to remove rIVCF when they are no longer indicated. However, major obstacles exist to filter retrieval, chief among them being poor clinical follow-up. The establishment of a dedicated IVC filter service line, or clinic, has been shown to improve filter retrieval rates. Usage of particular devices, specifically permanent versus retrievable filters, is enhanced by prospective physician consultation. In this article, the rationale behind a dedicated IVC filter service line is presented as well as described the structure and activities of the authors' IVC filter clinic; supporting data will also be provided when appropriate.
Barbera, M.; Branduardi-Raymont, G.; Collura, A.; Comastri, A.; Eder, J.; Kamisiński, T.; Lo Cicero, U.; Meidinger, N.; Mineo, T.; Molendi, S.; Parodi, G.; Pilch, A.; Piro, L.; Rataj, M.; Rauw, G.; Sciortino, L.; Sciortino, S.; Wawer, P.
2015-08-01
ATHENA is the L2 mission selected by ESA to pursue the science theme "Hot and Energetic Universe" (launch scheduled in 2028). One of the key instruments of ATHENA is the Wide Field Imager (WFI) which will provide imaging in the 0.1-15 keV band over a 40'x40' large field of view, together with spectrally and time-resolved photon counting. The WFI camera, based on arrays of DEPFET active pixel sensors, is also sensitive to UV/Vis photons. Optically generated electron-hole pairs may degrade the spectral resolution as well as change the energy scale by introducing a signal offset. For this reason, the use of an X-ray transparent optical blocking filter is needed to allow the observation of all type of X-ray sources that present a UV/Visible bright counterpart. In this paper, we describe the main activities that we are carrying on for the conceptual design of the optical blocking filter, that will be mounted on the filter wheel, in order to satisfy the scientific requirements on optical load from bright UV/Vis astrophysical source, to maximize the X-ray transmission, and to withstand the severe acoustic and vibration loads foreseen during launch.
Cong, Fengyu; Leppänen, Paavo H T; Astikainen, Piia; Hämäläinen, Jarmo; Hietanen, Jari K; Ristaniemi, Tapani
2011-09-30
The present study addresses benefits of a linear optimal filter (OF) for independent component analysis (ICA) in extracting brain event-related potentials (ERPs). A filter such as the digital filter is usually considered as a denoising tool. Actually, in filtering ERP recordings by an OF, the ERP' topography should not be changed by the filter, and the output should also be able to be modeled by the linear transformation. Moreover, an OF designed for a specific ERP source or component may remove noise, as well as reduce the overlap of sources and even reject some non-targeted sources in the ERP recordings. The OF can thus accomplish both the denoising and dimension reduction (reducing the number of sources) simultaneously. We demonstrated these effects using two datasets, one containing visual and the other auditory ERPs. The results showed that the method including OF and ICA extracted much more reliable components than the sole ICA without OF did, and that OF removed some non-targeted sources and made the underdetermined model of EEG recordings approach to the determined one. Thus, we suggest designing an OF based on the properties of an ERP to filter recordings before using ICA decomposition to extract the targeted ERP component. Copyright © 2011 Elsevier B.V. All rights reserved.
Dual Control of Giant Field-like Spin Torque in Spin Filter Tunnel Junctions
Tang, Y.-H.; Chu, F.-C.; Kioussis, Nicholas
2015-06-01
We predict a giant field-like spin torque, , in spin-filter (SF) barrier tunnel junctions in sharp contrast to existing junctions based on nonmagnetic passive barriers. We demonstrate that has linear bias behavior, is independent of the SF thickness, and has odd parity with respect to the SF’s exchange splitting. Thus, it can be selectively controlled via external bias or external magnetic field which gives rise to sign reversal of via magnetic field switching. The underlying mechanism is the interlayer exchange coupling between the noncollinear magnetizations of the SF and free ferromagnetic electrode via the nonmagnetic insulating (I) spacer giving rise to giant spin-dependent reflection at the SF/I interface. These findings suggest that the proposed field-like-spin-torque MRAM may provide promising dual functionalities for both ‘reading’ and ‘writing’ processes which require lower critical current densities and faster writing and reading speeds.
Infomax Algorithm for Filtering Airwaves in the Field of Seabed Logging
Directory of Open Access Journals (Sweden)
Adeel Ansari
2014-04-01
Full Text Available This research focuses on applying Independent Component Analysis (ICA in the field of Seabed Logging (SBL. ICA is a statistical method for transforming an observed multidimensional or multivariate dataset into its constituent components (sources that are statistically as independent from each other as possible. ICA-type de-convolution algorithm, Infomax is suitable for mixed signals de-convolution, is proposed and considered convenient depending upon the nature of the source and noise model, in the application of seabed logging. Infomax is applied in the domain of marine Controlled Source Electro Magnetic (CSEM sensing method used for the detection of hydrocarbons based reservoirs in seabed logging application. The task is to identify the air waves and to filter them out. The infomax algorithm of ICA is considered for filtering the airwaves.
CSIR Research Space (South Africa)
Salmon, BP
2011-07-01
Full Text Available -OPTIMIZATION OF THE EXTENDED KALMAN FILTER?S PARAMETERS FOR IMPROVED FEATURE EXTRACTION ON HYPER-TEMPORAL IMAGES yzB.P. Salmon, yzW. Kleynhans, zF. van den Bergh, yJ.C. Olivier, W.J. Marais and zK.J. Wessels yDepartment of Electrical, Electronic and Computer Engineering... mod- ulated cosine function to improve land cover separation [3]. This paper proposes an extension to [3], that each of the first two spectral bands be modelled separately as a triply modu- lated cosine function and is expressed as yi;k;b = i;k;b...
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.
Optimized low-cost-array field designs for photovoltaic systems
Energy Technology Data Exchange (ETDEWEB)
Post, H.N.; Carmichael, D.C.; Castle, J.A.
1982-01-01
As manager of the US Department of Energy Photovoltaic Systems Definition Project, Sandia National Laboratories is engaged in a comprehensive program to define and develop array field subsystems which can achieve the lowest possible lifecycle costs. The major activity of this program is described, namely, the design and development of optimized, modular array fields for photovoltaic (PV) systems. As part of this activity, design criteria and performance requirements for specific array subsystems including support structures, foundations, intermodule connections, field wiring, lightning protection, system grounding, site preparation, and monitoring and control have been defined and evaluated. Similarly, fully integrated flat-panel array field designs, optimized for lowest lifecycle costs, have been developed for system sizes ranging from 20 to 500 kW/sub p/. Key features, subsystem requirements, and projected costs for these array field designs are presented and discussed.
Field-design optimization with triangular heliostat pods
Domínguez-Bravo, Carmen-Ana; Bode, Sebastian-James; Heiming, Gregor; Richter, Pascal; Carrizosa, Emilio; Fernández-Cara, Enrique; Frank, Martin; Gauché, Paul
2016-05-01
In this paper the optimization of a heliostat field with triangular heliostat pods is addressed. The use of structures which allow the combination of several heliostats into a common pod system aims to reduce the high costs associated with the heliostat field and therefore reduces the Levelized Cost of Electricity value. A pattern-based algorithm and two pattern-free algorithms are adapted to handle the field layout problem with triangular heliostat pods. Under the Helio100 project in South Africa, a new small-scale Solar Power Tower plant has been recently constructed. The Helio100 plant has 20 triangular pods (each with 6 heliostats) whose positions follow a linear pattern. The obtained field layouts after optimization are compared against the reference field Helio100.
Filter-feeding, near-field flows, and the morphologies of colonial choanoflagellates
Kirkegaard, Julius B.; Goldstein, Raymond E.
2016-11-01
Efficient uptake of prey and nutrients from the environment is an important component in the fitness of all microorganisms, and its dependence on size may reveal clues to the origins of evolutionary transitions to multicellularity. Because potential benefits in uptake rates must be viewed in the context of other costs and benefits of size, such as varying predation rates and the increased metabolic costs associated with larger and more complex body plans, the uptake rate itself is not necessarily that which is optimized by evolution. Uptake rates can be strongly dependent on local organism geometry and its swimming speed, providing selective pressure for particular arrangements. Here we examine these issues for choanoflagellates, filter-feeding microorganisms that are the closest relatives of the animals. We explore the different morphological variations of the choanoflagellate Salpingoeca rosetta, which can exist as a swimming cell, as a sessile thecate cell, and as colonies of cells in various shapes. In the absence of other requirements and in a homogeneously nutritious environment, we find that the optimal strategy to maximize filter-feeding by the collar of microvilli is to swim fast, which favors swimming unicells. In large external flows, the sessile thecate cell becomes advantageous. Effects of prey diffusion are discussed and also found to be to the advantage of the swimming unicell.
Optimal linear array heading in a directional noise field
McDonnell, David C.
1992-01-01
Approved for public release; distribution is unlimited. This thesis discusses a procedure that optimizes the signal-to-noise ratio (SNR) detected by a linear array in a directional ambient noise field. The SNR can be optimized by minimizing the ambient noise detected by the array. For a given target location, each possible heading of the array centers the ambiguous beam of the array at a different true bearing. Therefore, each heading of the array will receive a different ambient noise lev...
First principles molecular dynamics without self-consistent field optimization
Souvatzis, Petros
2013-01-01
We present a first principles molecular dynamics approach that is based on time-reversible ex- tended Lagrangian Born-Oppenheimer molecular dynamics [Phys. Rev. Lett. 100, 123004 (2008)] in the limit of vanishing self-consistent field optimization. The optimization-free dynamics keeps the computational cost to a minimum and typically provides molecular trajectories that closely follow the exact Born-Oppenheimer potential energy surface. Only one single diagonalization and Hamiltonian (or Fockian) costruction are required in each integration time step. The proposed dy- namics is derived for a general free-energy potential surface valid at finite electronic temperatures within hybrid density functional theory. Even in the event of irregular functional behavior that may cause a dynamical instability, the optimization-free limit represents an ideal starting guess for force calculations that may require a more elaborate iterative electronic ground state optimization. Our optimization-free dynamics thus represents ...
He, Fei; Liu, Yuanning; Zhu, Xiaodong; Huang, Chun; Han, Ye; Dong, Hongxing
2014-12-01
Gabor descriptors have been widely used in iris texture representations. However, fixed basic Gabor functions cannot match the changing nature of diverse iris datasets. Furthermore, a single form of iris feature cannot overcome difficulties in iris recognition, such as illumination variations, environmental conditions, and device variations. This paper provides multiple local feature representations and their fusion scheme based on a support vector regression (SVR) model for iris recognition using optimized Gabor filters. In our iris system, a particle swarm optimization (PSO)- and a Boolean particle swarm optimization (BPSO)-based algorithm is proposed to provide suitable Gabor filters for each involved test dataset without predefinition or manual modulation. Several comparative experiments on JLUBR-IRIS, CASIA-I, and CASIA-V4-Interval iris datasets are conducted, and the results show that our work can generate improved local Gabor features by using optimized Gabor filters for each dataset. In addition, our SVR fusion strategy may make full use of their discriminative ability to improve accuracy and reliability. Other comparative experiments show that our approach may outperform other popular iris systems.
Directory of Open Access Journals (Sweden)
Šaponjić Đorđe
2009-01-01
Full Text Available By applying the well known dualism: mean count rate - mean time between successive pulses - the equivalence between an IIR digital filter and a preset count digital rate meter has been demonstrated. By using a bank of four second order IIR filters and an optimized automated algorithm for filter selection, a practical realization of a preset count rate meter giving good tradeoff between statistical fluctuations and speed of response, particularly at low count rates such as background monitoring, is presented. The presented solution is suitable for designing portable count rate meters. The designed prototype is capable of operating up to 3600 pulses per second with an accuracy of over 4% in steady-state and response times of 1 second for the rising edge and 2 seconds for the falling edge of the mean count rate step-change.
Directory of Open Access Journals (Sweden)
Jian Ding
2013-11-01
Full Text Available This paper is concerned with the linear unbiased minimum variance estimation problem for discrete-time stochastic linear control systems with one-step random delay and inconsecutive packet dropout. A new model is developed to describe the phenomena of the one-step delay and inconsecutive packet dropout by employing a Bernoulli distributed stochastic variable. Based on the model, a recursive linear unbiased optimal filter in the linear minimum variance sense is designed by the method of completing the square. The solution to the linear filter is given by three equations including a Riccati equation, a Lyapunov equation and a simple difference equation. A sufficient condition for the existence of the steady-state filter is given. A simulation shows the effectiveness of the proposed algorithm.
Optimal O(1 Bilateral Filter with Arbitrary Spatial and Range Kernels Using Sparse Approximation
Directory of Open Access Journals (Sweden)
Shengdong Pan
2014-01-01
Full Text Available A number of acceleration schemes for speeding up the time-consuming bilateral filter have been proposed in the literature. Among these techniques, the histogram-based bilateral filter trades the flexibility for achieving O(1 computational complexity using box spatial kernel. A recent study shows that this technique can be leveraged for O(1 bilateral filter with arbitrary spatial and range kernels by linearly combining the results of multiple-box bilateral filters. However, this method requires many box bilateral filters to obtain sufficient accuracy when approximating the bilateral filter with a large spatial kernel. In this paper, we propose approximating arbitrary spatial kernel using a fixed number of boxes. It turns out that the multiple-box spatial kernel can be applied in many O(1 acceleration schemes in addition to the histogram-based one. Experiments on the application to the histogram-based acceleration are presented in this paper. Results show that the proposed method has better accuracy in approximating the bilateral filter with Gaussian spatial kernel, compared with the previous histogram-based methods. Furthermore, the performance of the proposed histogram-based bilateral filter is robust with respect to the parameters of the filter kernel.
Efficient generation of correlated random numbers using Chebyshev-optimal magnitude-only IIR filters
Rodríguez, A; Johnson, Steven G.; Rodriguez, Alejandro
2007-01-01
We compare several methods for the efficient generation of correlated random sequences (colored noise) by filtering white noise to achieve a desired correlation spectrum. We argue that a class of IIR filter-design techniques developed in the 1970s, which obtain the global Chebyshev-optimum minimum-phase filter with a desired magnitude and arbitrary phase, are uniquely suited for this problem but have seldom been used. The short filters that result from such techniques are crucial for applications of colored noise in physical simulations involving random processes, for which many long random sequences must be generated and computational time and memory are at a premium.
Wang, Jun; Meng, Xiaohong; Guo, Lianghui; Chen, Zhaoxi; Li, Fang
2014-10-01
We present a correlation coefficient analysis (CCA) method for obtaining threshold when using singular value decomposition (SVD) filtering method to reduce noise in potential field data. Before computation of correlation coefficients, SVD is performed on the gridded potential field data with the purpose of obtaining singular values of the data. A sliding window is utilized to truncate the acquired singular values, which allows us to obtain different singular value sequences. The lower limit of the sliding window is generally set to zero and the upper limit of the sliding window is the threshold. Then, we calculate and plot the correlation coefficients associated with the initial sequence and the newly obtained sequences, choosing the inflection point of the plotted correlation coefficients as the threshold. The CCA method offers a quantitative way to determine a threshold, which can be easily implemented by a computer program. We illustrate the method using synthetic datasets and field data from a metallic deposit area in the middle-lower reaches of the Yangtze River in China. The results show that the proposed method is effective and is able to provide an optimal threshold.
HDR Pathological Image Enhancement Based on Improved Bias Field Correction and Guided Image Filter
Directory of Open Access Journals (Sweden)
Qingjiao Sun
2016-01-01
Full Text Available Pathological image enhancement is a significant topic in the field of pathological image processing. This paper proposes a high dynamic range (HDR pathological image enhancement method based on improved bias field correction and guided image filter (GIF. Firstly, a preprocessing including stain normalization and wavelet denoising is performed for Haematoxylin and Eosin (H and E stained pathological image. Then, an improved bias field correction model is developed to enhance the influence of light for high-frequency part in image and correct the intensity inhomogeneity and detail discontinuity of image. Next, HDR pathological image is generated based on least square method using low dynamic range (LDR image, H and E channel images. Finally, the fine enhanced image is acquired after the detail enhancement process. Experiments with 140 pathological images demonstrate the performance advantages of our proposed method as compared with related work.
Energy Technology Data Exchange (ETDEWEB)
Wang, S L; Singer, M A
2009-07-13
The purpose of this report is to evaluate the hemodynamic effects of renal vein inflow and filter position on unoccluded and partially occluded IVC filters using three-dimensional computational fluid dynamics. Three-dimensional models of the TrapEase and Gunther Celect IVC filters, spherical thrombi, and an IVC with renal veins were constructed. Hemodynamics of steady-state flow was examined for unoccluded and partially occluded TrapEase and Gunther Celect IVC filters in varying proximity to the renal veins. Flow past the unoccluded filters demonstrated minimal disruption. Natural regions of stagnant/recirculating flow in the IVC are observed superior to the bilateral renal vein inflows, and high flow velocities and elevated shear stresses are observed in the vicinity of renal inflow. Spherical thrombi induce stagnant and/or recirculating flow downstream of the thrombus. Placement of the TrapEase filter in the suprarenal vein position resulted in a large area of low shear stress/stagnant flow within the filter just downstream of thrombus trapped in the upstream trapping position. Filter position with respect to renal vein inflow influences the hemodynamics of filter trapping. Placement of the TrapEase filter in a suprarenal location may be thrombogenic with redundant areas of stagnant/recirculating flow and low shear stress along the caval wall due to the upstream trapping position and the naturally occurring region of stagnant flow from the renal veins. Infrarenal vein placement of IVC filters in a near juxtarenal position with the downstream cone near the renal vein inflow likely confers increased levels of mechanical lysis of trapped thrombi due to increased shear stress from renal vein inflow.
Filtered x-ray diode diagnostics fielded on the Z-accelerator for source power measurements
Energy Technology Data Exchange (ETDEWEB)
Chandler, G.A.; Deeney, C.; Cuneo, M. [and others
1998-06-02
Filtered x-ray diode, (XRD), detectors are used as primary radiation flux diagnostics on Sandia`s Z-accelerator, which generates nominally a 200 TW, 2 MJ, x-ray pulse. Given such flux levels and XRD sensitivities the detectors are being fielded 23 meters from the source. The standard diagnostic setup and sensitivities are discussed. Vitreous carbon photocathodes are being used to reduce the effect of hydrocarbon contamination present in the Z-machine vacuum system. Nevertheless pre- and post-calibration data taken indicate spectrally dependent changes in the sensitivity of these detectors by up to factors up to 2 or 3.
Optimized molecular force field for sulfur hexafluoride simulations.
Olivet, Aurelio; Vega, Lourdes F
2007-04-14
An optimized molecular force field for sulfur hexafluoride (SF6) simulations is presented in this work. The new force field for SF6 contains two parts: a Lennard-Jones potential that deals with F-F intermolecular interactions and the second term dealing with the intramolecular forces. In this second part the flexibility of the molecule is explicitly considered by 6 harmonic stretch terms, modeling the S-F chemical bonds, and 12 harmonic bending terms, modeling the F-S-F angular deformations. The parameters of the new force field have been obtained by a multivariable optimization procedure, whose main feature is the simultaneous fitting of all force field parameters, using as reference data several equilibrium properties (vapor pressure, saturated liquid density, and surface tension) and shear viscosity. The new force field clearly improves the description of the phase envelope and the rest of the properties as compared to previous simulations for a rigid model for the same molecule [A. Olivet et al., J. Chem. Phys. 123, 194508 (2005)]. Results for the optimized force field concerning the vapor-liquid coexistence curve, several thermodynamics states at the homogeneous gas and liquid region, and transport coefficients of SF6 are in good agreement with available experimental data.
Piehowski, Paul D; Petyuk, Vladislav A; Sandoval, John D; Burnum, Kristin E; Kiebel, Gary R; Monroe, Matthew E; Anderson, Gordon A; Camp, David G; Smith, Richard D
2013-03-01
For bottom-up proteomics, there are wide variety of database-searching algorithms in use for matching peptide sequences to tandem MS spectra. Likewise, there are numerous strategies being employed to produce a confident list of peptide identifications from the different search algorithm outputs. Here we introduce a grid-search approach for determining optimal database filtering criteria in shotgun proteomics data analyses that is easily adaptable to any search. Systematic Trial and Error Parameter Selection--referred to as STEPS--utilizes user-defined parameter ranges to test a wide array of parameter combinations to arrive at an optimal "parameter set" for data filtering, thus maximizing confident identifications. The benefits of this approach in terms of numbers of true-positive identifications are demonstrated using datasets derived from immunoaffinity-depleted blood serum and a bacterial cell lysate, two common proteomics sample types.
Optimizing nitrification in biological rapid sand filters for drinking water production
DEFF Research Database (Denmark)
Albrechtsen, Hans-Jørgen; Smets, Barth F.; Lee, Carson Odell
Addition of phosphate or trace metals or better management e.g. in terms of anmonium load can improve the nitrification rate and efficiency in biological rapid sand filters.......Addition of phosphate or trace metals or better management e.g. in terms of anmonium load can improve the nitrification rate and efficiency in biological rapid sand filters....
Energy Technology Data Exchange (ETDEWEB)
Presser, Cary; Nazarian, Ashot; Conny, Joseph M.; Chand, Duli; Sedlacek, Arthur; Hubbe, John M.
2016-12-02
Absorptivity measurements with a laser-heating approach, referred to as the laser-driven thermal reactor (LDTR), were carried out in the infrared and applied at ambient (laboratory) non-reacting conditions to particle-laden filters from a three-wavelength (visible) particle/soot absorption photometer (PSAP). The particles were obtained during the Biomass Burning Observation Project (BBOP) field campaign. The focus of this study was to determine the particle absorption coefficient from field-campaign filter samples using the LDTR approach, and compare results with other commercially available instrumentation (in this case with the PSAP, which has been compared with numerous other optical techniques). Advantages of the LDTR approach include 1) direct determination of material absorption, 2) information on the filter optical properties, and 3) identification of the filter material effects on particle absorption (e.g., leading to particle absorption enhancement or shadowing). For measurements carried out under ambient conditions, the particle absorptivity is obtained with a thermocouple placed flush with the filter back surface and the laser probe beam impinging normal to the filter particle-laden surface. Thus, in principle one can employ a simple experimental arrangement to measure simultaneously both the transmissivity and absorptivity (at different discrete wavelengths) and ascertain the particle absorption coefficient. For this investigation, LDTR measurements were carried out with PSAP filters (pairs with both blank and exposed filters) from eight different days during the campaign, having relatively light but different particle loadings. The observed particles coating the filters were found to be carbonaceous (having broadband absorption characteristics). The LDTR absorbance compared well with results from both the PSAP. The analysis was also expanded to account for the filter fiber scattering on particle absorption in assessing particle absorption enhancement
Generating the optimal magnetic field for magnetic refrigeration
DEFF Research Database (Denmark)
Bjørk, Rasmus; Insinga, Andrea Roberto; Smith, Anders
2016-01-01
remanence distribution for any desired magnetic field. The method is based on the reciprocity theorem, which through the use of virtual magnets can be used to calculate the optimal remanence distribution. Furthermore, we present a method for segmenting a given magnet design that always results...
Optimizing the configuration patterns for heterogeneous distributed sensor fields
Wettergren, Thomas A.; Costa, Russell
2012-06-01
When unmanned distributed sensor fields are developed for rapid deployment in hostile areas, the deployment may consist of multiple sensor types. This occurs because of the variations in expected threats and uncertainties about the details of the local environmental conditions. As more detailed information is available at deployment, the quantity and types of sensors are given and fixed, yet the specific pattern for the configuration of their deployment is still variable. We develop a new optimization approach for planning these configurations for this resource constrained sensor application. Our approach takes into account the variety of sensors available and their respective expected performance in the environment, as well as the target uncertainty. Due to the large dimensionality of the design space for this unmanned sensor planning problem, heuristic-based optimizations will provide very sub-optimal solutions and gradient-based methods lack a good quality initialization. Instead, we utilize a robust optimization procedure that combines genetic algorithms with nonlinear programming techniques to create numerical solutions for determining the optimal spatial distribution of sensing effort for each type of sensor. We illustrate the effectiveness of the approach on numerical examples, and also illustrate the qualitative difference in the optimal patterns as a function of the relative numbers of available sensors of each type. We conclude by using the optimization results to discuss the benefits of interspersing the different sensor types, as opposed to creating area sub-segmentations for each type.
Gollub, Caroline; Kowalewski, Markus; de Vivie-Riedle, Regina
2008-08-15
We present a modified optimal control scheme based on the Krotov method, which allows for strict limitations on the spectrum of the optimized laser fields. A frequency constraint is introduced and derived mathematically correct, without losing monotonic convergence of the algorithm. The method guarantees a close link to learning loop control experiments and is demonstrated for the challenging control of nonresonant Raman transitions, which are used to implement a set of global quantum gates for molecular vibrational qubits.
Compact low field magnetic resonance imaging magnet: Design and optimization
Sciandrone, M.; Placidi, G.; Testa, L.; Sotgiu, A.
2000-03-01
Magnetic resonance imaging (MRI) is performed with a very large instrument that allows the patient to be inserted into a region of uniform magnetic field. The field is generated either by an electromagnet (resistive or superconductive) or by a permanent magnet. Electromagnets are designed as air cored solenoids of cylindrical symmetry, with an inner bore of 80-100 cm in diameter. In clinical analysis of peripheral regions of the body (legs, arms, foot, knee, etc.) it would be better to adopt much less expensive magnets leaving the most expensive instruments to applications that require the insertion of the patient in the magnet (head, thorax, abdomen, etc.). These "dedicated" apparati could be smaller and based on resistive magnets that are manufactured and operated at very low cost, particularly if they utilize an iron yoke to reduce power requirements. In order to obtain good field uniformity without the use of a set of shimming coils, we propose both particular construction of a dedicated magnet, using four independently controlled pairs of coils, and an optimization-based strategy for computing, a posteriori, the optimal current values. The optimization phase could be viewed as a low-cost shimming procedure for obtaining the desired magnetic field configuration. Some experimental measurements, confirming the effectiveness of the proposed approach (construction and optimization), have also been reported. In particular, it has been shown that the adoption of the proposed optimization based strategy has allowed the achievement of good uniformity of the magnetic field in about one fourth of the magnet length and about one half of its bore. On the basis of the good experimental results, the dedicated magnet can be used for MRI of peripheral regions of the body and for animal experimentation at very low cost.
Cheng, Zhongtao; Liu, Dong; Zhou, Yudi; Yang, Yongying; Zhang, Yupeng; Luo, Jing; Bai, Jian; Liu, Chong; Shen, Yibing
2016-05-01
We propose and develop a field-widened Michelson interferometer (FWMI) system to act as a new type of spectroscopic filter in HSRL application. Due to the field widening characteristic, the FWMI can allow relatively large off-axis incident angle, and can be designed to any desirable wavelength. The theoretical foundations of the FWMI are introduced in this paper, and the developed prototype interferometer is described. It consists of a solid arm made of the glass H-ZF52 with the dimension of 37.876 mm, and an air gap with the length of 20.382 mm. These two interference arms are connected to a cube beam splitter to constitute a Michelson interferometer. Due to the matched dimensions and refractive indices of the two arms, the experimental testing results show that the OPD variation of the developed FWMI is about 0.04 lambda and the RMS is less than 0.008 lambda when the incident angle is as much as 1.5 degree (half angle). The cumulative wavefront distortion caused by the FWMI is less than 0.1 lambda PV value and 0.02 lambda RMS value. To lock the filtering frequency of the FWMI to the laser transmitter, a frequency locking system, which is actually an electro-optic feedback loop, is established. The setup and principle of this frequency locking system are also described in detail. Good locking accuracy of the FWMI about 27MHz is demonstrated through the frequency locking technique. All these results validate the feasibility of this developed FWMI system as a spectroscopic filter of an HSRL.
Field Study of Filter Sampling Artifacts for Inorganic and Organic Aerosol Species
Maenhaut, W.; Wang, W.; Chi, X.
2009-12-01
It is well-known that the collection of carbonaceous aerosols on quartz fibre filters is prone to both positive and negative artifacts (e.g., Turpin et al., 2000). In studies on these artifacts, one normally concentrates on organic carbon (OC) as a whole or occasionally on water-soluble OC (WSOC). It is rare that studies are carried on individual organic species. Examples of the latter type of study are those by Limbeck et al. (2001; 2005), who used a low-volume tandem filter set-up at a rural background site in South Africa and at the urban site Vienna in Austria, and measured dicarboxylic acids (DCAs) on the front and back filters. We conducted a similar study as those of Limbeck et al. (2001; 2005). For our study we collected high-volume PM2.5 samples during summer field campaigns at three European forested sites, i.e., in Hungary, Belgium, and Finland. The front and back filters of our samples were analysed for OC with a thermal-optical transmission technique (Birch & Cary, 1996), for WSOC as described by Viana et al. (2006), and for water-soluble inorganic cationic and anionic species and organic anionic species by suppressed ion chromatography with conductometric detection. The organic species measured included methanesulphonic acid (MSA) and the four major DCAs, i.e., oxalic, malonic, succinic, and glutaric. The median back/front percentage ratios for ammonium and sulphate were low, below 5% and 1%, respectively, but for nitrate they were around 25-30%. That undenuded filter samplings for nitrate are prone to artifacts is well-documented (e.g., Schaap et al., 2004). For OC the median back/front percentage ratios were around 15% and for WSOC around 20%. For MSA and the four DCAs, they increased in the following order: oxalic (1.5%), succinic (3%), MSA (4%), malonic (2-9%), glutaric (7-26%). Our back/front ratios for three of the four DCAs are lower to much lower than these found by Limbeck et al. (2001; 2005); for malonic, however, we found higher back
Evolutionary Optimization of State Selective Field Ionization for Quantum Computing
Jones, M L; Majeed, H O; Varcoe, B T H
2009-01-01
State selective field ionization detection techniques in physics require a specific progression through a complicated atomic state space to optimize state selectivity and overall efficiency. For large principle quantum number n, the theoretical models become computationally intractable and any results are often rendered irrelevant by small deviations from ideal experimental conditions, for example external electromagnetic fields. Several different proposals for quantum information processing rely heavily upon the quality of these detectors. In this paper, we show a proof of principle that it is possible to optimize experimental field profiles in situ by running a genetic algorithm to control aspects of the experiment itself. A simple experiment produced novel results that are consistent with analyses of existing results.
Analytical optimization for field emission of carbon nanotube array
Institute of Scientific and Technical Information of China (English)
WANG XinQing; LI Liang; CHEN Min; JIN HongXiao; JIN DingFeng; PENG Min; GE HongLiang
2009-01-01
To optimize field emission (FE) property of carbon nanotube (CNT) array on a planar cathode surface,the Fowler-Nordheim formula has been used to discuss the maximum of the emission current density with the floating sphere model in this paper. The emission current density is dominating as the ane-lytical Fowler-Nordheim function of the intertube distance, and the maximum of the emission current density is deduced and discussed. The results indicate that the intertube distance in CNT array criti-cally affects the field enhancement factor and the emission current density, whose maximum occurs at the intertube distance approximating a tenth of the tube height. Considering the emission current den-sity and the field enhancement factor, the FE can be optimized analytically when the intertube distance is about a tenth of the tube height.
A performance optimized architecture of deblocking filter for H.264/AVC
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The in-loop deblocking filter is one of the complex parts in H.264/AVC. It has such a large amount of computation that almost all the pixels in all the frames are involved in the worst case. In this paper, a fast deblocking filter architecture is proposed, and it can effectively save the operating time. In the proposed architecture, two 1-D filters are introduced so that the vertical filtering and the horizontal filtering can be performed at the same time, Only 120 cycles are needed for a macroblock. Our architecture is also a memory efficient one, and only one 4×4 pixels register, one 4×4 transpose array and one 16×32 b two-port (SRAM) are used as buffers in the filtering process. The simulation and synthesis results show that, with almost the same or even smaller area than some 1-D filter based architectures before, the proposed one can save more than 40% processing time. The architecture is suitable for real-time applications and can easily achieve the requirement of processing real-time video in 1080HD (high definition format, 1 920×1 088@30 fps) at 100 MHz.
Filter-feeding, near-field flows, and the morphologies of colonial choanoflagellates
Kirkegaard, Julius B
2016-01-01
Efficient uptake of nutrients from the environment is an important component in the fitness of all microorganisms, and its dependence on size may reveal clues to the origins of evolutionary transitions to multicellularity. Because potential benefits in uptake rates must be viewed in the context of other costs and benefits of size, such as varying predation rates and the increased metabolic costs associated with larger and more complex body plans, the uptake rate itself is not necessarily that which is optimized by evolution. Uptake rates can be strongly dependent on local organism geometry and its swimming speed, providing selective pressure for particular arrangements. Here we examine these issues for choanoflagellates, filter-feeding microorganisms that are the closest relatives of the animals. We explore the different morphological variations of the choanoflagellete $Salpingoeca~rosetta$, which can exist as a swimming cell, a sessile thecate cell, and as colonies of cells in various shapes. In the absence ...
Li, J. C.; Gong, B.; Wang, H. G.
2016-08-01
Optimal development of shale gas fields involves designing a most productive fracturing network for hydraulic stimulation processes and operating wells appropriately throughout the production time. A hydraulic fracturing network design-determining well placement, number of fracturing stages, and fracture lengths-is defined by specifying a set of integer ordered blocks to drill wells and create fractures in a discrete shale gas reservoir model. The well control variables such as bottom hole pressures or production rates for well operations are real valued. Shale gas development problems, therefore, can be mathematically formulated with mixed-integer optimization models. A shale gas reservoir simulator is used to evaluate the production performance for a hydraulic fracturing and well control plan. To find the optimal fracturing design and well operation is challenging because the problem is a mixed integer optimization problem and entails computationally expensive reservoir simulation. A dynamic simplex interpolation-based alternate subspace (DSIAS) search method is applied for mixed integer optimization problems associated with shale gas development projects. The optimization performance is demonstrated with the example case of the development of the Barnett Shale field. The optimization results of DSIAS are compared with those of a pattern search algorithm.
Field trial of an HTS filter system on a CDMA base station
Institute of Scientific and Technical Information of China (English)
YIN ZheSheng; LIANG Yong; WANG Fan; H. PIEL; B. AMINOV; F. AMINOVA; M. GETTA; S. KOLESOV; A. KNACK; N. PUPETER; D. WEHLER; WEI Bin; CAO BiSong; WANG Xin; GUO XuBo; ZHANG XiaoPing; GAO LongMa; PIAO YunLong; ZHU MaFeng
2007-01-01
This paper presents the field trial results of a high temperature superconductor filter system (HTSFS) in a code division multiple access (CDMA) mobile communication base station (BTS) in Tangshan, China. The center frequency of the HTSFS is 830 MHz with 1.4% fractional bandwidth. The noise figure (NF) of the HTSFS, including connectors and cables, is 0.8 dB. The field trial results show that after the HTSFS was installed in the receiver front-end of a CDMA base station, the transmitting power of handset was decreased by 3.1 dB on average. Up to now, the HTSFS has been running steadily in the base station for more than 22 months, demonstrating the reliability and stability of the system.
Hopp, C. J.; Savage, M. K.; Townend, J.; Sherburn, S.
2016-12-01
Monitoring patterns in local microseismicity gives clues to the existence and location of subsurface structures. In the context of a geothermal reservoir, subsurface structures often indicate areas of high permeability and are vitally important in understanding fluid flow within the geothermal resource. Detecting and locating microseismic events within an area of power generation, however, is often challenging due to high levels of noise associated with nearby power plant infrastructure. In this situation, matched filter detection improves drastically upon standard earthquake detection techniques, specifically when events are likely induced by fluid injection and are therefore near-repeating. Using an earthquake catalog of 637 events which occurred between 1 January and 18 November 2015 as our initial dataset, we implemented a matched filtering routine for the Mighty River Power (MRP) geothermal fields at Rotokawa and Ngatamariki, central North Island, New Zealand. We detected nearly 21,000 additional events across both geothermal fields, a roughly 30-fold increase from the original catalog. On average, each of the 637 template events detected 45 additional events throughout the study period, with a maximum number of additional detections for a single template of 359. Cumulative detection rates for all template events, in general, do not mimic large scale changes in injection rates within the fields, however we do see indications of an increase in detection rate associated with power plant shutdown at Ngatamariki. Locations of detected events follow established patterns of historic seismicity at both Ngatamariki and Rotokawa. One large cluster of events persists in the southeastern portion of Rotokawa and is likely bounded to the northwest by a known fault dividing the injection and production sections of the field. Two distinct clusters of microseismicity occur in the North and South of Ngatamariki, the latter appearing to coincide with a structure dividing the
Phase field model for optimization of multi-material structural topology in two and three dimensions
Zhou, Shiwei
The Optimization of Structural Topology (OST) is a breakthrough in product design because it can optimize size, shape and topology synchronously under different physical constraints. It has promising applications in industry ranging from automobile and aerospace engineering to micro electromechanical system. This dissertation first substitutes the nonlinear diffusion method for filter process in the optimization of structural topology. Filtering has been a major technique used in a homogenization-based method for topology optimization of structures. It plays a key role in regularizing the basic problem into a well-behaved setting. But it has a drawback of smoothing effect around the boundary of material domain. A diffusion technique is presented here as a variational approach to the regularization of the topology optimization problem. A nonlinear or anisotropic diffusion process not only leads to a suitable problem regularization but also exhibits strong "edge"-preserving characteristics. Thus, it shows that the use of the nonlinear diffusions brings desirable effects of boundary preservation and even enhancement of lower-dimensional features such as flow-like structures. The proposed diffusion techniques have a close relationship with the diffusion methods and the phase-field methods of the fields of materials and digital image processing. Then this dissertation introduces a gradient flow in the norm of H-1 for the problem of multi-material structural topology optimization in 2/3D with a generalized Cahn-Hilliard (C-H) model with elasticity. Unlike the traditional C-H model applied to spinodal separation which only has bulk energy and interface energy, the generalized model couples the macroscopic elastic energy (mean compliance) into the total free energy. As a result, the grain morphology is not random islands or zigzag web-like objects but regular truss or bar structure. Although disturbed by elastic energy, the C-H system still keeps its two most important
Optimization of a Segmented Filter with a New Error Diffusion Approach
Institute of Scientific and Technical Information of China (English)
Ayman; Al; Falou; Marwa; ELBouz
2003-01-01
The segmented filters, based on spectral cutting, proved their efficiency for the multi-correlation. In this article we propose an optimisation of this cutting according to a new error diffusion method.
Optimal features selection based on circular Gabor filters and RSE in texture segmentation
Wang, Qiong; Liu, Jian; Tian, Jinwen
2007-12-01
This paper designs the circular Gabor filters incorporating into the human visual characteristics, and the concept of mutual information entropy in rough set is introduced to evaluate the effect of the features extracted from different filters on clustering, redundant features are got rid of, Experimental results indicate that the proposed algorithm outperforms conventional approaches in terms of both objective measurements and visual evaluation in texture segmentation.
Coherent destruction of tunneling with optimally designed polychromatic external field
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Subhasree, E-mail: subhasree81@gmail.com [Department of Chemistry, Serampore College, Hooghly (India); Talukder, Srijeeta; Sen, Shrabani; Chaudhury, Pinaki [Department of Chemistry, University of Calcutta, 92 APC Road, Kolkata 700 009 (India)
2013-11-08
Highlights: • We design polychromatic fields causing CDT. • The field intensity is kept very low (∼10{sup 5} a.u). • We have used Floquet analysis for determining the two lowest quasi-energy states. • SA method is used as a stochastic optimizer to minimize the energy gap. • Quantum phase space dynamics has been obtained by using TDFGH method. - Abstract: A suitably designed polychromatic field with a very low field strength and low frequency (∼10{sup -5} atomic unit) can bring about coherent destruction of tunneling (CDT) in a symmetric double well system. It is analyzed that in the presence of an external perturbation the difference of energy between the two lowest quasi-energy states may increase or decrease depending on the spatial and temporal nature of the perturbation. We have designed sets of polychromatic fields both spatially symmetric and antisymmetric, which cause CDT in symmetric double well system. A stochastic optimizer (Simulated Annealing) has been used to design such a polychromatic field periodic in time. Both spatial symmetry preserving or symmetry breaking perturbations may cause CDT for a symmetric double well potential.
Optimal adaptive focusing through heterogeneous media with the minimally invasive inverse filter.
Vignon, François; de Rosny, Julien; Aubry, Jean-François; Fink, Mathias
2007-11-01
The inverse filter is a technique used to adaptively focus waves through heterogeneous media. It is based on the inversion of the Green's functions matrix between the M transducers of a focusing array and N control points in the focal area. The inverse filter minimizes the pressure deposited around the focal point. However it is highly invasive, requiring the presence of N transducers or hydrophones in the focal area at the control points' locations to measure the Green's functions. This paper presents a way of reaching the inverse filter's focusing quality with a minimally invasive setup: only one transducer (at the desired focal location) is needed. This minimally invasive inverse filter takes advantage of the fact all the information about the propagation medium can be retrieved from the signals backscattered by the medium towards the focusing array, if the propagation medium is lossless. A numerical simulation is performed to test this minimally invasive inverse filter through a scattering, lossless medium. The focusing quality equals the conventional, highly invasive inverse filter's. The average spatial and temporal contrast is increased by up to 10 dB compared to the time reversal focusing.
Energy Technology Data Exchange (ETDEWEB)
Vicente, J. de; Sanchez, E.; Sevilla, I.; Castilla, J.; Ponce, R.; Sanchez, F. J.
2012-04-11
The photometric redshift is an active area of research. It is becoming the preferred method for redshift measurement above spectroscopy one for large surveys. In these surveys, the requirement in redshift precision is relaxed in benefit of obtaining the measurements of large number of galaxies. One of the more relevant decisions to be taken in the design of a photometric redshift experiment is the number of filters since it affects deeply to the precision and survey time. Currently, there is not a clear method for evaluating the impact in both precision and exposure time of a determined filter partition set and usually it is determined by detailed simulations on the behavior of photo-z algorithms. In this note we describe GASDRA, a new method for extracting the minimal signal to noise requirement, depending on the number of filters needed for preserving the filtered spectrum shape, and hence to make feasible the spectrum identification. The application of this requirement guaranties a determined precision in the spectrum measurement. Although it cannot be translated directly to absolute photometric redshift error, it does provide a method for comparing the relative precision achieved in the spectrum representation by different sets of filters. We foresee that this relative precision is close related to photo-z error. In addition, we can evaluate the impact in the exposure time of any filter partition set with respect to other. (Author) 11 refs.
Equivalent (uniform) square field sizes of flattening filter free photon beams
Lechner, Wolfgang; Kuess, Peter; Georg, Dietmar; Palmans, Hugo
2017-10-01
Various types of treatment units, such as CyberKnife, TomoTherapy and C-arm linear accelerators (LINACs) are operated using flattening filter free (FFF) photon beams. Their reference dosimetry, however, is currently based on codes of practice that provide data which were primarily developed and tested for high-energy photon beams with flattening filter (WFF). The aim of this work was to introduce equivalent uniform square field sizes of FFF beams to serve as a basis of a unified reference dosimetry procedure applicable to all aforementioned FFF machines. For this purpose, in-house determined experimental data together with published data of the ratio of doses at depths of 20 cm and 10 cm in water (D 20,10) were used to characterize the depth dose distribution of 6 and 10 MV WFF and FFF beams. These data were analyzed for field sizes ranging from 2 × 2 cm2 to 40 × 40 cm2. A scatter function that takes the lateral profiles of the individual beams into account was fitted to the experimental data. The lateral profiles of the WFF beams were assumed to be uniform, while those of the FFF beams were approximated using fourth or sixth order polynomials. The scatter functions of the FFF beams were recalculated using a uniform lateral profile (the same as the physical profile of the WFF beams), and are henceforth denoted as virtual uniform FFF beams (VUFFF). The field sizes of the VUFFF beams having the same scatter contribution as the corresponding FFF beams at a given field size were defined as the equivalent uniform square field (EQUSF) size. Data from four different LINACs with 18 different beams in total, as well as a CyberKnife beam, were analyzed. The average values of EQUSFs over all investigated LINACs of the conventional 10 × 10 cm2 reference fields of 6 MV and 10 MV FFF beams for C-arm LINACs and machine-specific reference fields for CyberKnife and TomoTherapy were 9.5 cm, 9 cm, 5.0 cm and 6.5 cm respectively. The
Directory of Open Access Journals (Sweden)
Carlos Pozo
Full Text Available Optimization models in metabolic engineering and systems biology focus typically on optimizing a unique criterion, usually the synthesis rate of a metabolite of interest or the rate of growth. Connectivity and non-linear regulatory effects, however, make it necessary to consider multiple objectives in order to identify useful strategies that balance out different metabolic issues. This is a fundamental aspect, as optimization of maximum yield in a given condition may involve unrealistic values in other key processes. Due to the difficulties associated with detailed non-linear models, analysis using stoichiometric descriptions and linear optimization methods have become rather popular in systems biology. However, despite being useful, these approaches fail in capturing the intrinsic nonlinear nature of the underlying metabolic systems and the regulatory signals involved. Targeting more complex biological systems requires the application of global optimization methods to non-linear representations. In this work we address the multi-objective global optimization of metabolic networks that are described by a special class of models based on the power-law formalism: the generalized mass action (GMA representation. Our goal is to develop global optimization methods capable of efficiently dealing with several biological criteria simultaneously. In order to overcome the numerical difficulties of dealing with multiple criteria in the optimization, we propose a heuristic approach based on the epsilon constraint method that reduces the computational burden of generating a set of Pareto optimal alternatives, each achieving a unique combination of objectives values. To facilitate the post-optimal analysis of these solutions and narrow down their number prior to being tested in the laboratory, we explore the use of Pareto filters that identify the preferred subset of enzymatic profiles. We demonstrate the usefulness of our approach by means of a case study
Pozo, Carlos; Guillén-Gosálbez, Gonzalo; Sorribas, Albert; Jiménez, Laureano
2012-01-01
Optimization models in metabolic engineering and systems biology focus typically on optimizing a unique criterion, usually the synthesis rate of a metabolite of interest or the rate of growth. Connectivity and non-linear regulatory effects, however, make it necessary to consider multiple objectives in order to identify useful strategies that balance out different metabolic issues. This is a fundamental aspect, as optimization of maximum yield in a given condition may involve unrealistic values in other key processes. Due to the difficulties associated with detailed non-linear models, analysis using stoichiometric descriptions and linear optimization methods have become rather popular in systems biology. However, despite being useful, these approaches fail in capturing the intrinsic nonlinear nature of the underlying metabolic systems and the regulatory signals involved. Targeting more complex biological systems requires the application of global optimization methods to non-linear representations. In this work we address the multi-objective global optimization of metabolic networks that are described by a special class of models based on the power-law formalism: the generalized mass action (GMA) representation. Our goal is to develop global optimization methods capable of efficiently dealing with several biological criteria simultaneously. In order to overcome the numerical difficulties of dealing with multiple criteria in the optimization, we propose a heuristic approach based on the epsilon constraint method that reduces the computational burden of generating a set of Pareto optimal alternatives, each achieving a unique combination of objectives values. To facilitate the post-optimal analysis of these solutions and narrow down their number prior to being tested in the laboratory, we explore the use of Pareto filters that identify the preferred subset of enzymatic profiles. We demonstrate the usefulness of our approach by means of a case study that optimizes the
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
DEFF Research Database (Denmark)
Hameed, Ibahim; Bochtis, D.; Sørensen, C.A.
2013-01-01
automation technologies. Since the primary goal of an agricultural vehicle is the complete coverage of the cropped area within the field, an essential prerequisite is the capability of the mobile unit to cover the whole field area autonomously. In this paper, the main objective is to develop an approach......-field obstacle areas, the headland paths generation for the field and each obstacle area, the implementation of a genetic algorithm to optimize the sequence that the field robot vehicle will follow to visit the blocks, and an algorithmically generation of the task sequences derived from the farmer practices...
Wang, Xuan; Tandeo, Pierre; Fablet, Ronan; Husson, Romain; Guan, Lei; Chen, Ge
2016-01-01
The swell propagation model built on geometric optics is known to work well when simulating radiated swells from a far located storm. Based on this simple approximation, satellites have acquired plenty of large samples on basin-traversing swells induced by fierce storms situated in mid-latitudes. How to routinely reconstruct swell fields with these irregularly sampled observations from space via known swell propagation principle requires more examination. In this study, we apply 3-h interval pseudo SAR observations in the ensemble Kalman filter (EnKF) to reconstruct a swell field in ocean basin, and compare it with buoy swell partitions and polynomial regression results. As validated against in situ measurements, EnKF works well in terms of spatial–temporal consistency in far-field swell propagation scenarios. Using this framework, we further address the influence of EnKF parameters, and perform a sensitivity analysis to evaluate estimations made under different sets of parameters. Such analysis is of key interest with respect to future multiple-source routinely recorded swell field data. Satellite-derived swell data can serve as a valuable complementary dataset to in situ or wave re-analysis datasets. PMID:27898005
Wang, Xuan; Tandeo, Pierre; Fablet, Ronan; Husson, Romain; Guan, Lei; Chen, Ge
2016-11-25
The swell propagation model built on geometric optics is known to work well when simulating radiated swells from a far located storm. Based on this simple approximation, satellites have acquired plenty of large samples on basin-traversing swells induced by fierce storms situated in mid-latitudes. How to routinely reconstruct swell fields with these irregularly sampled observations from space via known swell propagation principle requires more examination. In this study, we apply 3-h interval pseudo SAR observations in the ensemble Kalman filter (EnKF) to reconstruct a swell field in ocean basin, and compare it with buoy swell partitions and polynomial regression results. As validated against in situ measurements, EnKF works well in terms of spatial-temporal consistency in far-field swell propagation scenarios. Using this framework, we further address the influence of EnKF parameters, and perform a sensitivity analysis to evaluate estimations made under different sets of parameters. Such analysis is of key interest with respect to future multiple-source routinely recorded swell field data. Satellite-derived swell data can serve as a valuable complementary dataset to in situ or wave re-analysis datasets.
Parameter optimization of temperature field in RF-capacitive hyperthermia
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
To realize a certain target temperature distribution in tumor tissues and avoid over-heating in normal tissues in radio frequency (RF)-capacitive hyperthermia, an objective function and some weight coefficients are introduced. Then using the 2-D finite element method, the electromagnetic and bio-heat transfer equations are solved, and using the genetic algorithm the heating configurations are recursively modified to minimize the objective function. Finally an optimum solution of the expected heating field distribution in hyperthermia is achieved. And with a human heterogeneous tissue model extracted from X-ray CT images, satisfactory optimization results are obtained in the simulations on a biplate RF-capacitive hyperthermia device. This optimization technique for controlling the body temperature field has shown scientific importance and practical values in the research of hyperthermia.
Optimal use of conservation and accessibility filters in microRNA target prediction.
Directory of Open Access Journals (Sweden)
Ray M Marín
Full Text Available It is generally accepted that filtering microRNA (miRNA target predictions by conservation or by accessibility can reduce the false discovery rate. However, these two strategies are usually not exploited in a combined and flexible manner. Here, we introduce PACCMIT, a flexible method that filters miRNA binding sites by their conservation, accessibility, or both. The improvement in performance obtained with each of these three filters is demonstrated on the prediction of targets for both i highly and ii weakly conserved miRNAs, i.e., in two scenarios in which the miRNA-target interactions are subjected to different evolutionary pressures. We show that in the first scenario conservation is a better filter than accessibility (as both sensitivity and precision are higher among the top predictions and that the combined filter improves performance of PACCMIT even further. In the second scenario, on the other hand, the accessibility filter performs better than both the conservation and combined filters, suggesting that the site conservation is not equally effective in rejecting false positive predictions for all miRNAs. Regarding the quality of the ranking criterion proposed by Robins and Press and used in PACCMIT, it is shown that top ranking interactions correspond to more downregulated proteins than do the lower ranking interactions. Comparison with several other target prediction algorithms shows that the ranking of predictions provided by PACCMIT is at least as good as the ranking generated by other conservation-based methods and considerably better than the energy-based ranking used in other accessibility-based methods.
Shibutani, Takayuki; Onoguchi, Masahisa; Yamada, Tomoki; Kamida, Hiroki; Kunishita, Kohei; Hayashi, Yuuki; Nakajima, Tadashi; Kinuya, Seigo
2016-06-01
Myocardial perfusion single photon emission computed tomography (SPECT) is typically subject to a variation in image quality due to the use of different acquisition protocols, image reconstruction parameters and image display settings by each institution. One of the principal image reconstruction parameters is the Butterworth filter cut-off frequency, a parameter strongly affecting the quality of myocardial images. The objective of this study was to formulate a flowchart for the determination of the optimal parameters of the Butterworth filter for filtered back projection (FBP), ordered subset expectation maximization (OSEM) and collimator-detector response compensation OSEM (CDR-OSEM) methods using the evaluation system of the myocardial image based on technical grounds phantom. SPECT studies were acquired for seven simulated defects where the average counts of the normal myocardial components of 45° left anterior oblique projections were approximately 10-120 counts/pixel. These SPECT images were then reconstructed by FBP, OSEM and CDR-OSEM methods. Visual and quantitative assessment of short axis images were performed for the defect and normal parts. Finally, we formulated a flowchart indicating the optimal image processing procedure for SPECT images. Correlation between normal myocardial counts and the optimal cut-off frequency could be represented as a regression expression, which had high or medium coefficient of determination. We formulated the flowchart in order to optimize the image reconstruction parameters based on a comprehensive assessment, which enabled us to perform objectively processing. Furthermore, the usefulness of image reconstruction using the flowchart was demonstrated by a clinical case.
Fast Filtered Imaging of the C-2U Advanced Beam-Driven Field-Reversed Configuration
Granstedt, E. M.; Petrov, P.; Knapp, K.; Cordero, M.; Patel, V.; the TAE Team
2015-11-01
The goal of the C-2U program is to sustain a Field-Reversed Configuration (FRC) for 5+ ms using neutral beam injection, end-biasing, and various particle fueling techniques. Three high-speed, filtered cameras are used to observe visible light emission from deuterium pellet ablation and compact-toroid injection which are used for auxiliary particle fueling. The instruments are also used to view the dynamics of the macroscopic plasma evolution, identify regions of strong plasma-material interactions, and visualize non-axisymmetric perturbations. To achieve the necessary viewing geometry, imaging lenses are mounted in re-entrant viewports, two of which are mounted on bellows for retraction during gettering and removal if cleaning is necessary. Images are coupled from the imaging lens to the camera via custom lens-based optical periscopes. Each instrument contains a remote-controlled filter wheel which is set between shots to select a particular emission line from neutral D or various charge states of He, C, O, or Ti. Measurements of absolute emissivity and estimates of neutral and impurity density will be presented.
Optimization and performance of an optically asymmetrical heliostat field
Energy Technology Data Exchange (ETDEWEB)
Romero, M.; Fernandez, V. [CIEMAT, Centro de Investigacion Energica Medioambiental y Technologia, DER (Spain); Sanchez, M. [Commission Europeenne, DG XII, Bruxelles (Belgium)
1999-03-01
The recent trend of integrating CRS into hybrid plants with combined cycles is creating a new situation, since the solar field is forced to make use of sites near gas pipelines and industrial areas. Land there becomes a significant portion of plant cost and constraints lead to some particular problems for layout optimization and subsequent optical performance. The COLON SOLAR heliostat field represented a real challenge during the design phase, because of the important restrictions stemming from the available site. Field optimization required adapting the existing codes to the COLON SOLAR site, since the field is not oriented to the North, is narrower than required and presents a number of restrictions associated with industrial pipelines and electrical grids (both aerial and buried) found on the site. Flux distributions on the absorber surface obtained with HELIOS and DELSOL3 demonstrated that in any given situation the centroid shifted about 25 to the East because of the higher number of heliostats to the West. The influence of such peculiarities in the field on design and the minimization of their effect on plant performance are discussed. (authors)
Optimization Studies of a Single-Stage Magnetic Field Accelerator
Bedrosian, Paul
1996-05-01
The use of electromagnetic propulsion as a method of energy conversion is the subject of much current research. A single-stage magnetic field accelerator (MFA) was designed and built to investigate design parameters of the system. Using a ballistic pendulum, the efficieny of energy transfer was looked at for a number of physical and electrical parameters. The resulting optimization of a single-stage MFA will be helpful in the design and development of future multi-stage MFA's.
Numerical Investigation and Optimization of SBS-Based Slow-Light Using Filtered Incoherent Pump
Institute of Scientific and Technical Information of China (English)
ZHENG Di; PAN Wei; YAN Lian-Shan; LUO Bin; ZOU Xi-Hua; WEN Kun-Hua; JIANG Ning
2009-01-01
The performance of stimulated Brillouin scattering(SBS)-based slow light using a novel spectrally-sliced broad band incoherent pump source is numerically studied.The profile of the pump-power spectrum is determined by the transmission spectra of the optical filter followed by the polarized broadband incoherent pump source.We also investigate the performance of Gaussian-type and super-Gaussian-type filtering under different spectrally-sliced bandwidths and pump power levels for 2.5 Gbit/s return-to-zero pulse(50% duty-cycle).The pulse broadening is characterized by the full width of half maximum(FWHM)and the rms pulse width,respectively.However,the results obtained by the two kinds of measurement methods deviate from each other with increasing pump power.Compared with the regular Gaussian-type filtering,the pulse broadening can be significantly reduced using super-Gaussian-type filtering at the cost of a small reduction in delay time.Furthermore,the maximum improvement in pulse broadening of △B_(FWHM) = 28.4% and △B_(RMS)= 10.4% is achieved by using a five-order super-Gaussian-type filter and a pump power of 500mw.
First principles molecular dynamics without self-consistent field optimization
Energy Technology Data Exchange (ETDEWEB)
Souvatzis, Petros, E-mail: petros.souvatsiz@fysik.uu.se [Department of Physics and Astronomy, Division of Materials Theory, Uppsala University, Box 516, SE-75120 Uppsala (Sweden); Niklasson, Anders M. N., E-mail: amn@lanl.gov [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2014-01-28
We present a first principles molecular dynamics approach that is based on time-reversible extended Lagrangian Born-Oppenheimer molecular dynamics [A. M. N. Niklasson, Phys. Rev. Lett. 100, 123004 (2008)] in the limit of vanishing self-consistent field optimization. The optimization-free dynamics keeps the computational cost to a minimum and typically provides molecular trajectories that closely follow the exact Born-Oppenheimer potential energy surface. Only one single diagonalization and Hamiltonian (or Fockian) construction are required in each integration time step. The proposed dynamics is derived for a general free-energy potential surface valid at finite electronic temperatures within hybrid density functional theory. Even in the event of irregular functional behavior that may cause a dynamical instability, the optimization-free limit represents a natural starting guess for force calculations that may require a more elaborate iterative electronic ground state optimization. Our optimization-free dynamics thus represents a flexible theoretical framework for a broad and general class of ab initio molecular dynamics simulations.
First principles molecular dynamics without self-consistent field optimization.
Souvatzis, Petros; Niklasson, Anders M N
2014-01-28
We present a first principles molecular dynamics approach that is based on time-reversible extended Lagrangian Born-Oppenheimer molecular dynamics [A. M. N. Niklasson, Phys. Rev. Lett. 100, 123004 (2008)] in the limit of vanishing self-consistent field optimization. The optimization-free dynamics keeps the computational cost to a minimum and typically provides molecular trajectories that closely follow the exact Born-Oppenheimer potential energy surface. Only one single diagonalization and Hamiltonian (or Fockian) construction are required in each integration time step. The proposed dynamics is derived for a general free-energy potential surface valid at finite electronic temperatures within hybrid density functional theory. Even in the event of irregular functional behavior that may cause a dynamical instability, the optimization-free limit represents a natural starting guess for force calculations that may require a more elaborate iterative electronic ground state optimization. Our optimization-free dynamics thus represents a flexible theoretical framework for a broad and general class of ab initio molecular dynamics simulations.
Raffensperger, Jeff P.; Baker, Anna C.; Blomquist, Joel D.; Hopple, Jessica A.
2017-06-26
Quantitative estimates of base flow are necessary to address questions concerning the vulnerability and response of the Nation’s water supply to natural and human-induced change in environmental conditions. An objective of the U.S. Geological Survey National Water-Quality Assessment Project is to determine how hydrologic systems are affected by watershed characteristics, including land use, land cover, water use, climate, and natural characteristics (geology, soil type, and topography). An important component of any hydrologic system is base flow, generally described as the part of streamflow that is sustained between precipitation events, fed to stream channels by delayed (usually subsurface) pathways, and more specifically as the volumetric discharge of water, estimated at a measurement site or gage at the watershed scale, which represents groundwater that discharges directly or indirectly to stream reaches and is then routed to the measurement point.Hydrograph separation using a recursive digital filter was applied to 225 sites in the Chesapeake Bay watershed. The recursive digital filter was chosen for the following reasons: it is based in part on the assumption that groundwater acts as a linear reservoir, and so has a physical basis; it has only two adjustable parameters (alpha, obtained directly from recession analysis, and beta, the maximum value of the base-flow index that can be modeled by the filter), which can be determined objectively and with the same physical basis of groundwater reservoir linearity, or that can be optimized by applying a chemical-mass-balance constraint. Base-flow estimates from the recursive digital filter were compared with those from five other hydrograph-separation methods with respect to two metrics: the long-term average fraction of streamflow that is base flow, or base-flow index, and the fraction of days where streamflow is entirely base flow. There was generally good correlation between the methods, with some biased
优化FIR数字滤波器的FPGA实现%Implementation of Optimal FIR Filter Based on FPGA
Institute of Scientific and Technical Information of China (English)
邹兴宇; 程树英
2011-01-01
The traditional FIR digital filter was modified with the concept of increasing the speed and reducing the area. Taking into account of the characteristics of FPGA, the Booth Radix-2 algorithm multiplier and the fast adder were designed in the combination with CSA adder and a tree structure, and then the adder and multiplier were used successfully in the design of FIR digital filter.The coefficients of the filter were generated by Matlab. Simulation and synthesis results show that Booth algorithm multiplier and adder tree based on CSA algorithm not only meet the performance requirements of FIR digital filter but also optimize the area on the circuit and especially the speed, and the optimization is more evident when there are a large amount of data.%基于提高速度和减少面积的理念,对传统的FIR数字滤波器进行改良.考虑到FPGA的实现特点,研究并设计了采用Radix-2的Booth算法乘法器以及结合了CSA加法器和树型结构的快速加法器,并成功应用于FIR数字滤波器的设计中.滤波器的系数由Matlab设计产生.仿真和综合结果表明,Booth算法乘法嚣和CSA算法加法器树,在满足FIR数字滤波器的性能要求的同时,在电路实现面积上、尤其是速度上有明显的优化;并且当数据量越多时,优化也越明显.
Energy Technology Data Exchange (ETDEWEB)
Nebot Sanz, E.; Romero Garcia, L.I.; Quiroga Alonso, J.M.; Sales Marquez, D. (Departamento de Ingenieria Quimica, Universidad de Cadiz, Cadiz (Spain))
1994-01-01
In this work, the optimization of thermophilic anaerobic process, using Anaerobic Filter technology was studied. Feed of the Anaerobic Filter was wine-distillery wastewaters. The experiments developed were carried out at lab-scale downflow anaerobic filter reactors. Reactors were filled with a high porous plastic media (Flocor-R). The media support entities have a high surface/volume ratio. Test were run to determine the maximum organic load attainable in the system for wich both, the depurative efficiency and the methane production were optimum. Likewise, the effect of organic load on the anaerobic filter performance were studied. (Author) 15 refs. (Author)
Single-Channel Noise Reduction using Unified Joint Diagonalization and Optimal Filtering
DEFF Research Database (Denmark)
Nørholm, Sidsel Marie; Benesty, Jacob; Jensen, Jesper Rindom;
2014-01-01
In this paper, the important problem of single-channel noise reduction is treated from a new perspective. The problem is posed as a filtering problem based on joint diagonalization of the covariance matrices of the desired and noise signals. More specifically, the eigenvectors from the joint...... diagonalization corresponding to the least significant eigenvalues are used to form a filter, which effectively estimates the noise when applied to the observed signal. This estimate is then subtracted from the observed signal to form an estimate of the desired signal, i.e., the speech signal. In doing this, we...
Design and optimization of fundamental mode filters based on long-period fiber gratings
Chen, Ming-Yang; Wei, Jin; Sheng, Yong; Ren, Nai-Fei
2016-07-01
A segment of long-period fiber grating (LPFG) that can selectively filter the fundamental mode in the few-mode optical fiber is proposed. By applying an appropriate chosen surrounding material and an apodized configuration of LPFG, high fundamental mode loss and low high-order core mode loss can be achieved simultaneously. In addition, we propose a method of cascading LPFGs with different periods to expand the bandwidth of the mode filter. Numerical simulation shows that the operating bandwidth of the cascade structure can be as large as 23 nm even if the refractive index of the surrounding liquid varies with the environment temperature.
On Optimal Linear Filtering of Speech for Near-End Listening Enhancement
DEFF Research Database (Denmark)
Taal, Cees H.; Jensen, Jesper; Leijon, Arne
2013-01-01
In this letter the focus is on linear filtering of speech before degradation due to additive background noise. The goal is to design the filter such that the speech intelligibility index (SII) is maximized when the speech is played back in a known noisy environment. Moreover, a power constraint...... suboptimal. In this work we propose a nonlinear approximation of the SII which is accurate for all SNRs. Experiments show large intelligibility improvements with the proposed method over the unprocessed noisy speech and better performance than one state-of-the art method....
Optimized FPGA Implementation of Multi-Rate FIR Filters Through Thread Decomposition
Kobayashi, Kayla N.; He, Yutao; Zheng, Jason X.
2011-01-01
Multi-rate finite impulse response (MRFIR) filters are among the essential signal-processing components in spaceborne instruments where finite impulse response filters are often used to minimize nonlinear group delay and finite precision effects. Cascaded (multistage) designs of MRFIR filters are further used for large rate change ratio in order to lower the required throughput, while simultaneously achieving comparable or better performance than single-stage designs. Traditional representation and implementation of MRFIR employ polyphase decomposition of the original filter structure, whose main purpose is to compute only the needed output at the lowest possible sampling rate. In this innovation, an alternative representation and implementation technique called TD-MRFIR (Thread Decomposition MRFIR) is presented. The basic idea is to decompose MRFIR into output computational threads, in contrast to a structural decomposition of the original filter as done in the polyphase decomposition. A naive implementation of a decimation filter consisting of a full FIR followed by a downsampling stage is very inefficient, as most of the computations performed by the FIR state are discarded through downsampling. In fact, only 1/M of the total computations are useful (M being the decimation factor). Polyphase decomposition provides an alternative view of decimation filters, where the downsampling occurs before the FIR stage, and the outputs are viewed as the sum of M sub-filters with length of N/M taps. Although this approach leads to more efficient filter designs, in general the implementation is not straightforward if the numbers of multipliers need to be minimized. In TD-MRFIR, each thread represents an instance of the finite convolution required to produce a single output of the MRFIR. The filter is thus viewed as a finite collection of concurrent threads. Each of the threads completes when a convolution result (filter output value) is computed, and activated when the first
Institute of Scientific and Technical Information of China (English)
侯旺; 梅风华; 陈国军; 邓喜文
2015-01-01
An evaluation of infrared image complexity is proposed based on the background optimal filtering to solve the problem that the traditional methods have given poor results in the background evaluation. Meanwhile, the optimal filtering scale for infrared image filtering can be given by this method, it will provide a guidance for optimal infrared image filtering. First, we generate the Gaussian simulated target and fuse it to the infrared image to obtain the real infrared image with the simulated target. Then, this image is filtered in different scales and the signal-to-noise ratio of the target after filtering is calculated. Finally, the maximal value of signal-to-noise ratio of the target is used as the background optimal filter scale, to evaluate the infrared image complexity. Besides, the infrared filtering scale is deduced by establishing the mathematic model, and then the mathematical expression of optimal filtering scale is obtained. A lot of experiments indicate that: 1) The mathematical expression of optimal filtering scale agrees with the experimental results. 2) The result of our method is better than that of the traditional methods based on information entropy. Because the optimal filtering scale is obtained by using our method, we can use this scale to filter the infrared image to effectively detect a small target. 3) When the scale of simulated target increases, the optimal filtering scale increases accordingly. So, when we calculate the infrared image complexity, the scale of simulated target must be the same. We can compare the infrared image complexity between different images. Moreover, the optimal filtering scale is independent of the intensity of simulated target. 4) The effect of Gaussian and Butterworth high-pass filter is better than that of the ideal high-pass filter in the proposed method. 5) The infrared image complexity can be analyzed by the proposed method effectively. Moreover, changes of different image contents can be analyzed by using
Energy Technology Data Exchange (ETDEWEB)
Manstein, Heiko; Rothmann, Andreas [Scandinavia Freudenberg Filtration Technologies KG, Weinheim (Germany). Turbomachinery
2009-07-01
Efficient air filtration and its contribution towards cost-effective operation of gas turbines offer an extensive field for continual design enhancements. The utility value of three-stage, high-efficiency filter installations for gasturbine air intake systems was in terms of its basics covered by a previous publication. Feedback from multi-stage systems installed in the field validates the applicability to statically operated filter systems currently in common use, against the background of the stipulations posed for particle arrestance, coalescence characteristics and pressure-loss behaviour. (orig.)
Zhang, De-Jia
2009-07-01
With the fast development of Internet, many systems have emerged in e-commerce applications to support the product recommendation. Collaborative filtering is one of the most promising techniques in recommender systems, providing personalized recommendations to users based on their previously expressed preferences in the form of ratings and those of other similar users. In practice, with the adding of user and item scales, user-item ratings are becoming extremely sparsity and recommender systems utilizing traditional collaborative filtering are facing serious challenges. To address the issue, this paper presents an approach to compute item genre similarity, through mapping each item with a corresponding descriptive genre, and computing similarity between genres as similarity, then make basic predictions according to those similarities to lower sparsity of the user-item ratings. After that, item-based collaborative filtering steps are taken to generate predictions. Compared with previous methods, the presented collaborative filtering employs the item genre similarity can alleviate the sparsity issue in the recommender systems, and can improve accuracy of recommendation.
Energy Technology Data Exchange (ETDEWEB)
Sebastien Massart [CERFACS / URA 1875, 42 Avenue Gaspard Coriolis, 31057 Toulouse Cedex 01, (France)
2005-07-01
Imperviousness of French nuclear power plants containments has to secure radioactive products confinement during incident or accident. Temporal evolution of containments is obtained through the numerical model Code Aster that purpose is to detect if some fissure could appear and as a consequence, imperviousness lost. In parallel, sensors are placed all around the containments to follow real time deformations. In this paper, Kalman filter analysis of an extensometer data is used to optimize eight parameters of the numerical model Code Aster. This method allows us to improve the concrete delayed behaviors modelization and supplies uncertainties to the forecast of the containment evolution. (author)
车用空气滤清器总成性能分析与优化%Analysis and Optimization of Air Filter Assembly Performance
Institute of Scientific and Technical Information of China (English)
曹培元; 杜爱民; 杜玉彪; 冯桂军
2012-01-01
提出了混合优化设计的概念,在考虑空气滤清器流动性能和降噪两大指标的前提下对空气滤清器作出整体优化.计算过程中利用有限元分析前处理软件HyperMesh进行了网格划分,利用声学分析软件Sysnoise对空气滤清器总成进行了声学性能计算,利用流场分析软件Fluent进行了进气流场和压降分析,最后依据各分析结果提出了针对空气滤清器结构改进的合理优化方案,使其在满足结构要求的前提下,传递损失和压力损失得到了较大的改善.%The concept of mixed optimization was put forward. Based on the flow performance and denoising of air filter, the overall optimization was carried out. During the calculation, the Hypermesh FEA software was used for the mesh generation, the Sysnoise acoustic software was used to calculate the acoustic performance and the Fluent fluid software was used to analyze the intake flow field and pressure loss. Finally the feasible optimized scheme for the structure-improved air filter model was acquired, which improved transfer and pressure loss under meeting the structural requirements.
Diego Azcona, Juan; Barbés, Benigno; Wang, Lilie; Burguete, Javier
2016-01-01
This paper presents a method to obtain the pencil-beam kernels that characterize a megavoltage photon beam generated in a flattening filter free (FFF) linear accelerator (linac) by deconvolution from experimental measurements at different depths. The formalism is applied to perform independent dose calculations in modulated fields. In our previous work a formalism was developed for ideal flat fluences exiting the linac’s head. That framework could not deal with spatially varying energy fluences, so any deviation from the ideal flat fluence was treated as a perturbation. The present work addresses the necessity of implementing an exact analysis where any spatially varying fluence can be used such as those encountered in FFF beams. A major improvement introduced here is to handle the actual fluence in the deconvolution procedure. We studied the uncertainties associated to the kernel derivation with this method. Several Kodak EDR2 radiographic films were irradiated with a 10 MV FFF photon beam from two linacs from different vendors, at the depths of 5, 10, 15, and 20cm in polystyrene (RW3 water-equivalent phantom, PTW Freiburg, Germany). The irradiation field was a 50mm diameter circular field, collimated with a lead block. The 3D kernel for a FFF beam was obtained by deconvolution using the Hankel transform. A correction on the low dose part of the kernel was performed to reproduce accurately the experimental output factors. Error uncertainty in the kernel derivation procedure was estimated to be within 0.2%. Eighteen modulated fields used clinically in different treatment localizations were irradiated at four measurement depths (total of fifty-four film measurements). Comparison through the gamma-index to their corresponding calculated absolute dose distributions showed a number of passing points (3%, 3mm) mostly above 99%. This new procedure is more reliable and robust than the previous one. Its ability to perform accurate independent dose calculations was
Gozani, S N; Miller, J P
1994-04-01
We describe advanced protocols for the discrimination and classification of neuronal spike waveforms within multichannel electrophysiological recordings. The programs are capable of detecting and classifying the spikes from multiple, simultaneously active neurons, even in situations where there is a high degree of spike waveform superposition on the recording channels. The protocols are based on the derivation of an optimal linear filter for each individual neuron. Each filter is tuned to selectively respond to the spike waveform generated by the corresponding neuron, and to attenuate noise and the spike waveforms from all other neurons. The protocol is essentially an extension of earlier work [1], [13], [18]. However, the protocols extend the power and utility of the original implementations in two significant respects. First, a general single-pass automatic template estimation algorithm was derived and implemented. Second, the filters were implemented within a software environment providing a greatly enhanced functional organization and user interface. The utility of the analysis approach was demonstrated on samples of multiunit electrophysiological recordings from the cricket abdominal nerve cord.
Directory of Open Access Journals (Sweden)
S. N. Naikwad
2009-01-01
Full Text Available A focused time lagged recurrent neural network (FTLR NN with gamma memory filter is designed to learn the subtle complex dynamics of a typical CSTR process. Continuous stirred tank reactor exhibits complex nonlinear operations where reaction is exothermic. It is noticed from literature review that process control of CSTR using neuro-fuzzy systems was attempted by many, but optimal neural network model for identification of CSTR process is not yet available. As CSTR process includes temporal relationship in the input-output mappings, time lagged recurrent neural network is particularly used for identification purpose. The standard back propagation algorithm with momentum term has been proposed in this model. The various parameters like number of processing elements, number of hidden layers, training and testing percentage, learning rule and transfer function in hidden and output layer are investigated on the basis of performance measures like MSE, NMSE, and correlation coefficient on testing data set. Finally effects of different norms are tested along with variation in gamma memory filter. It is demonstrated that dynamic NN model has a remarkable system identification capability for the problems considered in this paper. Thus FTLR NN with gamma memory filter can be used to learn underlying highly nonlinear dynamics of the system, which is a major contribution of this paper.
Comfort filters in a total energy demand optimization method for the passive design of a building
2015-01-01
The effective design of sustainable buildings results from an accurate optimization process of all the interrelated variables. The authors developed a replicable methodology for the optimization of the building envelope design. Following a previous work, where in the pre-processing and the optimization phases the minimization of the total energy demand is performed by coupling TRNSYS® with GenOpt®, this paper is focused on the post-processing phase of the methodology, in which the results are...
Energy Technology Data Exchange (ETDEWEB)
Bethel, E. Wes; Bethel, E. Wes
2012-01-06
This report explores using GPUs as a platform for performing high performance medical image data processing, specifically smoothing using a 3D bilateral filter, which performs anisotropic, edge-preserving smoothing. The algorithm consists of a running a specialized 3D convolution kernel over a source volume to produce an output volume. Overall, our objective is to understand what algorithmic design choices and configuration options lead to optimal performance of this algorithm on the GPU. We explore the performance impact of using different memory access patterns, of using different types of device/on-chip memories, of using strictly aligned and unaligned memory, and of varying the size/shape of thread blocks. Our results reveal optimal configuration parameters for our algorithm when executed sample 3D medical data set, and show performance gains ranging from 30x to over 200x as compared to a single-threaded CPU implementation.
Optimal Linear Filters. 2. Pulse Time Measurements in the Presence of Noise
Energy Technology Data Exchange (ETDEWEB)
Nygaard, K.
1966-09-15
The problem of calculating the maximum available timing information contained in nuclear pulses in the presence of noise is solved theoretically. Practical experiments show that the theoretical values can be obtained by very simple, but untraditional, means. An output pulse from a practical filter connected to a charge sensitive amplifier with a Ge(Li) detector showed a rise time of 30 ns and a noise level of less than 5 keV. The time jitter measured was inversely proportional to the pulse height and less than 30 ns for 10 keV pulses. With the timing filter shown solid state detectors can be classified somewhere between Nal scintillators and organic scintillators with respect to time resolution.
Houts, R. C.; Vaughn, G. L.
1974-01-01
Three algorithms are developed for designing finite impulse response digital filters to be used for pulse shaping and channel equalization. The first is the Minimax algorithm which uses linear programming to design a frequency-sampling filter with a pulse shape that approximates the specification in a minimax sense. Design examples are included which accurately approximate a specified impulse response with a maximum error of 0.03 using only six resonators. The second algorithm is an extension of the Minimax algorithm to design preset equalizers for channels with known impulse responses. Both transversal and frequency-sampling equalizer structures are designed to produce a minimax approximation of a specified channel output waveform. Examples of these designs are compared as to the accuracy of the approximation, the resultant intersymbol interference (ISI), and the required transmitted energy. While the transversal designs are slightly more accurate, the frequency-sampling designs using six resonators have smaller ISI and energy values.
Sanyal, Amit K.
2005-01-01
There are several attitude estimation algorithms in existence, all of which use local coordinate representations for the group of rigid body orientations. All local coordinate representations of the group of orientations have associated problems. While minimal coordinate representations exhibit kinematic singularities for large rotations, the quaternion representation requires satisfaction of an extra constraint. This paper treats the attitude estimation and filtering problem as an optimizati...
Horst, Reto; Horwich, Arthur L; Wüthrich, Kurt
2011-10-19
In structural biology, pulsed field gradient (PFG) NMR spectroscopy for the characterization of size and hydrodynamic parameters of macromolecular solutes has the advantage over other techniques that the measurements can be recorded with identical solution conditions as used for NMR structure determination or for crystallization trials. This paper describes two transverse-relaxation-optimized (TRO) (15)N-filtered PFG stimulated-echo (STE) experiments for studies of macromolecular translational diffusion in solution, (1)H-TRO-STE and (15)N-TRO-STE, which include CRINEPT and TROSY elements. Measurements with mixed micelles of the Escherichia coli outer membrane protein X (OmpX) and the detergent Fos-10 were used for a systematic comparison of (1)H-TRO-STE and (15)N-TRO-STE with conventional (15)N-filtered STE experimental schemes. The results provide an extended platform for evaluating the NMR experiments available for diffusion measurements in structural biology projects involving molecular particles with different size ranges. An initial application of the (15)N-TRO-STE experiment with very long diffusion delays showed that the tedradecamer structure of the 800 kDa Thermus thermophilus chaperonin GroEL is preserved in aqueous solution over the temperature range 25-60 °C.
Optimal Tuner Selection for Kalman Filter-Based Aircraft Engine Performance Estimation
Simon, Donald L.; Garg, Sanjay
2010-01-01
A linear point design methodology for minimizing the error in on-line Kalman filter-based aircraft engine performance estimation applications is presented. This technique specifically addresses the underdetermined estimation problem, where there are more unknown parameters than available sensor measurements. A systematic approach is applied to produce a model tuning parameter vector of appropriate dimension to enable estimation by a Kalman filter, while minimizing the estimation error in the parameters of interest. Tuning parameter selection is performed using a multi-variable iterative search routine which seeks to minimize the theoretical mean-squared estimation error. This paper derives theoretical Kalman filter estimation error bias and variance values at steady-state operating conditions, and presents the tuner selection routine applied to minimize these values. Results from the application of the technique to an aircraft engine simulation are presented and compared to the conventional approach of tuner selection. Experimental simulation results are found to be in agreement with theoretical predictions. The new methodology is shown to yield a significant improvement in on-line engine performance estimation accuracy
Gorsevski, Pece V.; Jankowski, Piotr
2010-08-01
The Kalman recursive algorithm has been very widely used for integrating navigation sensor data to achieve optimal system performances. This paper explores the use of the Kalman filter to extend the aggregation of spatial multi-criteria evaluation (MCE) and to find optimal solutions with respect to a decision strategy space where a possible decision rule falls. The approach was tested in a case study in the Clearwater National Forest in central Idaho, using existing landslide datasets from roaded and roadless areas and terrain attributes. In this approach, fuzzy membership functions were used to standardize terrain attributes and develop criteria, while the aggregation of the criteria was achieved by the use of a Kalman filter. The approach presented here offers advantages over the classical MCE theory because the final solution includes both the aggregated solution and the areas of uncertainty expressed in terms of standard deviation. A comparison of this methodology with similar approaches suggested that this approach is promising for predicting landslide susceptibility and further application as a spatial decision support system.
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.
Energy Technology Data Exchange (ETDEWEB)
Yarahmadi, Mehran [Kurdistan Univ. of Medical Sciences, Sanandaj (Iran, Islamic Republic of); Allahverdi, Mahmoud; Nedaie, Hassan A.; Asnaashari, Khadijeh; Vaezzadeh, Sayed A. [Tehran Univ. of Medical Sciences, Tehran (Iran, Islamic Republic of); Sauer, Otto A. [Wuerzburg Univ. (Germany). Klinik und Poliklinik fuer Strahlentherapie
2013-07-01
Background: In stereotactic radiosurgery, sharp beam edges have clear advantages to spare normal tissues. In general, the dose gradient is a limiting factor in minimizing dose to nearby critical structures for clinical cases. Therefore the penumbral width should be diminished. Methods: A Varian Clinac 2100 linear accelerator equipped with in-house designed radiosurgical collimator was modeled using the EGSnrc/BEAMnrc Monte Carlo code and compared with the measurements. The 0.015 cm{sup 3} PinPoint chamber was used to measure the 6 MV photon beam characteristics and to validate Monte Carlo calculations. Additional to the standard (STD) linac, a flattening filter free (FFF) linac was simulated. Percent depth doses, beam profiles and output factors were calculated for small field sizes with diameter of 5, 10, 20 and 30 mm with DOSXYZnrc. The mean energy and photon fluence at the water surface were calculated with BEAMDP for both FFF linac and STD linacs. Results: The penumbra width (80%-20%) was decreased by 0.5, 0.3, 0.2 and 0.2 mm for field sizes of 5, 10, 20 and 30 mm respectively when removing the FF. The fluence of photons at the surface increased up to 3.6 times and the mean energy decreased by a factor of 0.69 when removing the FF. The penumbra width (80%-20%) decreased by 17% when a 2 MeV monoenergetic electron pencil beam incident on the target is used instead of 6.2 MeV. Conclusions: It was found that the penumbra of small field sizes is decreased by removing the FF. Likewise using low megavoltage photons reduced the beam penumbra maintaining adequate penetration and skin sparing. (orig.)
Bhattacharya, Kolahal; Banerjee, Sudeshna; Mondal, Naba K.
2016-07-01
In the context of track fitting problems by a Kalman filter, the appropriate functional forms of the elements of the random process noise matrix are derived for tracking through thick layers of dense materials and magnetic field. This work complements the form of the process noise matrix obtained by Mankel [1].
Performance comparison of several optimization algorithms in matched field inversion
Institute of Scientific and Technical Information of China (English)
ZOU Shixin; YANG Kunde; MA Yuanliang
2004-01-01
Optimization efficiencies and mechanisms of simulated annealing, genetic algorithm, differential evolution and downhill simplex differential evolution are compared and analyzed. Simulated annealing and genetic algorithm use a directed random process to search the parameter space for an optimal solution. They include the ability to avoid local minima, but as no gradient information is used, searches may be relatively inefficient. Differential evolution uses information from a distance and azimuth between individuals of a population to search the parameter space, the initial search is effective, but the search speed decreases quickly because differential information between the individuals of population vanishes. Local downhill simplex and global differential evolution methods are developed separately, and combined to produce a hybrid downhill simplex differential evolution algorithm. The hybrid algorithm is sensitive to gradients of the object function and search of the parameter space is effective. These algorithms are applied to the matched field inversion with synthetic data. Optimal values of the parameters, the final values of object function and inversion time is presented and compared.
Field of view selection for optimal airborne imaging sensor performance
Goss, Tristan M.; Barnard, P. Werner; Fildis, Halidun; Erbudak, Mustafa; Senger, Tolga; Alpman, Mehmet E.
2014-05-01
The choice of the Field of View (FOV) of imaging sensors used in airborne targeting applications has major impact on the overall performance of the system. Conducting a market survey from published data on sensors used in stabilized airborne targeting systems shows a trend of ever narrowing FOVs housed in smaller and lighter volumes. This approach promotes the ever increasing geometric resolution provided by narrower FOVs, while it seemingly ignores the influences the FOV selection has on the sensor's sensitivity, the effects of diffraction, the influences of sight line jitter and collectively the overall system performance. This paper presents a trade-off methodology to select the optimal FOV for an imaging sensor that is limited in aperture diameter by mechanical constraints (such as space/volume available and window size) by balancing the influences FOV has on sensitivity and resolution and thereby optimizing the system's performance. The methodology may be applied to staring array based imaging sensors across all wavebands from visible/day cameras through to long wave infrared thermal imagers. Some examples of sensor analysis applying the trade-off methodology are given that highlights the performance advantages that can be gained by maximizing the aperture diameters and choosing the optimal FOV for an imaging sensor used in airborne targeting applications.
Tunable Imaging Filters in Astronomy
Bland-Hawthorn, J
2000-01-01
While tunable filters are a recent development in night time astronomy, they have long been used in other physical sciences, e.g. solar physics, remote sensing and underwater communications. With their ability to tune precisely to a given wavelength using a bandpass optimized for the experiment, tunable filters are already producing some of the deepest narrowband images to date of astrophysical sources. Furthermore, some classes of tunable filters can be used in fast telescope beams and therefore allow for narrowband imaging over angular fields of more than a degree over the sky.
Quaternionic Spatiotemporal Filtering for Dense Motion Field Estimation in Ultrasound Imaging
Directory of Open Access Journals (Sweden)
Adrien Marion
2010-01-01
Full Text Available Blood motion estimation provides fundamental clinical information to prevent and detect pathologies such as cancer. Ultrasound imaging associated with Doppler methods is often used for blood flow evaluation. However, Doppler methods suffer from shortcomings such as limited spatial resolution and the inability to estimate lateral motion. Numerous methods such as block matching and decorrelation-based techniques have been proposed to overcome these limitations. In this paper, we propose an original method to estimate dense fields of vector velocity from ultrasound image sequences. Our proposal is based on a spatiotemporal approach and considers 2D+t data as a 3D volume. Orientation of the texture within this volume is related to velocity. Thus, we designed a bank of 3D quaternionic filters to estimate local orientation and then calculate local velocities. The method was applied to a large set of experimental and simulated flow sequences with low motion (≈1 mm/s within small vessels (≈1 mm. Evaluation was conducted with several quantitative criteria such as the normalized mean error or the estimated mean velocity. The results obtained show the good behaviour of our method, characterizing the flows studied.
Quaternionic Spatiotemporal Filtering for Dense Motion Field Estimation in Ultrasound Imaging
Directory of Open Access Journals (Sweden)
Marion Adrien
2010-01-01
Full Text Available Abstract Blood motion estimation provides fundamental clinical information to prevent and detect pathologies such as cancer. Ultrasound imaging associated with Doppler methods is often used for blood flow evaluation. However, Doppler methods suffer from shortcomings such as limited spatial resolution and the inability to estimate lateral motion. Numerous methods such as block matching and decorrelation-based techniques have been proposed to overcome these limitations. In this paper, we propose an original method to estimate dense fields of vector velocity from ultrasound image sequences. Our proposal is based on a spatiotemporal approach and considers 2D+t data as a 3D volume. Orientation of the texture within this volume is related to velocity. Thus, we designed a bank of 3D quaternionic filters to estimate local orientation and then calculate local velocities. The method was applied to a large set of experimental and simulated flow sequences with low motion ( 1 mm/s within small vessels ( 1 mm. Evaluation was conducted with several quantitative criteria such as the normalized mean error or the estimated mean velocity. The results obtained show the good behaviour of our method, characterizing the flows studied.
SVD-Based Optimal Filtering Technique for Noise Reduction in Hearing Aids Using Two Microphones
Directory of Open Access Journals (Sweden)
Moonen Marc
2002-01-01
Full Text Available We introduce a new SVD-based (Singular value decomposition strategy for noise reduction in hearing aids. This technique is evaluated for noise reduction in a behind-the-ear (BTE hearing aid where two omnidirectional microphones are mounted in an endfire configuration. The behaviour of the SVD-based technique is compared to a two-stage adaptive beamformer for hearing aids developed by Vanden Berghe and Wouters (1998. The evaluation and comparison is done with a performance metric based on the speech intelligibility index (SII. The speech and noise signals are recorded in reverberant conditions with a signal-to-noise ratio of and the spectrum of the noise signals is similar to the spectrum of the speech signal. The SVD-based technique works without initialization nor assumptions about a look direction, unlike the two-stage adaptive beamformer. Still, for different noise scenarios, the SVD-based technique performs as well as the two-stage adaptive beamformer, for a similar filter length and adaptation time for the filter coefficients. In a diffuse noise scenario, the SVD-based technique performs better than the two-stage adaptive beamformer and hence provides a more flexible and robust solution under speaker position variations and reverberant conditions.
SVD-Based Optimal Filtering Technique for Noise Reduction in Hearing Aids Using Two Microphones
Maj, Jean-Baptiste; Moonen, Marc; Wouters, Jan
2002-12-01
We introduce a new SVD-based (Singular value decomposition) strategy for noise reduction in hearing aids. This technique is evaluated for noise reduction in a behind-the-ear (BTE) hearing aid where two omnidirectional microphones are mounted in an endfire configuration. The behaviour of the SVD-based technique is compared to a two-stage adaptive beamformer for hearing aids developed by Vanden Berghe and Wouters (1998). The evaluation and comparison is done with a performance metric based on the speech intelligibility index (SII). The speech and noise signals are recorded in reverberant conditions with a signal-to-noise ratio of [InlineEquation not available: see fulltext.] and the spectrum of the noise signals is similar to the spectrum of the speech signal. The SVD-based technique works without initialization nor assumptions about a look direction, unlike the two-stage adaptive beamformer. Still, for different noise scenarios, the SVD-based technique performs as well as the two-stage adaptive beamformer, for a similar filter length and adaptation time for the filter coefficients. In a diffuse noise scenario, the SVD-based technique performs better than the two-stage adaptive beamformer and hence provides a more flexible and robust solution under speaker position variations and reverberant conditions.
Martinek, Radek; Kahankova, Radana; Nazeran, Homer; Konecny, Jaromir; Jezewski, Janusz; Janku, Petr; Bilik, Petr; Zidek, Jan; Nedoma, Jan; Fajkus, Marcel
2017-05-19
This paper is focused on the design, implementation and verification of a novel method for the optimization of the control parameters (such as step size μ and filter order N) of LMS and RLS adaptive filters used for noninvasive fetal monitoring. The optimization algorithm is driven by considering the ECG electrode positions on the maternal body surface in improving the performance of these adaptive filters. The main criterion for optimal parameter selection was the Signal-to-Noise Ratio (SNR). We conducted experiments using signals supplied by the latest version of our LabVIEW-Based Multi-Channel Non-Invasive Abdominal Maternal-Fetal Electrocardiogram Signal Generator, which provides the flexibility and capability of modeling the principal distribution of maternal/fetal ECGs in the human body. Our novel algorithm enabled us to find the optimal settings of the adaptive filters based on maternal surface ECG electrode placements. The experimental results further confirmed the theoretical assumption that the optimal settings of these adaptive filters are dependent on the ECG electrode positions on the maternal body, and therefore, we were able to achieve far better results than without the use of optimization. These improvements in turn could lead to a more accurate detection of fetal hypoxia. Consequently, our approach could offer the potential to be used in clinical practice to establish recommendations for standard electrode placement and find the optimal adaptive filter settings for extracting high quality fetal ECG signals for further processing. Ultimately, diagnostic-grade fetal ECG signals would ensure the reliable detection of fetal hypoxia.
Kitakorn, Jatiyanon; I-Ming, Tang; Bumned, Soodchomshom
2016-07-01
Magneto transport of carriers with a spin-dependent gap in a ferromagnetic-gated bilayer of graphene is investigated. We focus on the effect of an energy gap induced by the mismatch of the exchange fields in the top and bottom layers of an AB-stacked graphene bilayer. The interplay of the electric and exchange fields causes the electron to acquire a spin-dependent energy gap. We find that, only in the case of the anti-parallel configuration, the effect of a magnetic-induced gap will give rise to perfect spin filtering controlled by the electric field. The resolution of the spin filter may be enhanced by varying the bias voltage. Perfect switching of the spin polarization from + 100% to -100% by reversing the direction of electric field is predicted. Giant magnetoresistance is predicted to be easily realized when the applied electric field is smaller than the magnetic energy gap. It should be pointed out that the perfect spin filter is due to the layer-dependent exchange energy. This work points to the potential application of bilayer graphene in spintronics. Project supported by the Kasetsart University Research and Development Institute (KURDI) and Thailand Research Fund (TRF) (Grant No. TRG5780274).
Tamura, Yuji; Takasaki, Shinji; Irokawa, Shoichi; Takeda, Hideo; Takagi, Kikuo; Noro, Yasuhiro; Ametani, Akihiro
AC filter design method for SVC and HVDC is commonly known in the relevant CIGRE technical brochure and IEC technical report. However the conventional method requires many iterative calculations of the harmonic voltages and currents until the calculation results become within the regulation levels by changing filter parameters based on the experience. In this respect, a new improved design method is proposed, which enables efficient evaluation on the complex impedance plane to confirm as to whether the proposed filter impedance is in the permissible range. In an actual project of Okuura SVC of Kyusyu Electric Power Co., Inc., the new method was applied to the AC filter design. This paper describes on the actual procedure of the AC filter design with the new method, the actual references of the harmonic performance calculation, and the field test measurement results on Okuura SVC. The calculation results and the filed measurement results are consistent with each other, thus the validity of the new design method is verified on its accuracy and effectiveness.
Field emission from optimized structure of carbon nanotube field emitter array
Chouhan, V.; Noguchi, T.; Kato, S.
2016-04-01
The authors report a detail study on the emission properties of field emitter array (FEA) of micro-circular emitters of multiwall carbon nanotubes (CNTs). The FEAs were fabricated on patterned substrates prepared with an array of circular titanium (Ti) islands on titanium nitride coated tantalum substrates. CNTs were rooted into these Ti islands to prepare an array of circular emitters. The circular emitters were prepared in different diameters and pitches in order to optimize their structure for acquiring a high emission current. The pitch was varied from 0 to 600 μm, while a diameter of circular emitters was kept constant to be 50 μm in order to optimize a pitch. For diameter optimization, a diameter was changed from 50 to 200 μm while keeping a constant edge-to-edge distance of 150 μm between the circular emitters. The FEA with a diameter of 50 μm and a pitch of 120 μm was found to be the best to achieve an emission current of 47 mA corresponding to an effective current density of 30.5 A/cm2 at 7 V/μm. The excellent emission current was attributed to good quality of CNT rooting into the substrate and optimized FEA structure, which provided a high electric field on a whole circular emitter of 50 μm and the best combination of the strong edge effect and CNT coverage. The experimental results were confirmed with computer simulation.
Optimization studies of the ITER low field side reflectometer.
Diem, S J; Wilgen, J B; Bigelow, T S; Hanson, G R; Harvey, R W; Smirnov, A P
2010-10-01
Microwave reflectometry will be used on ITER to measure the electron density profile, density fluctuations due to MHD/turbulence, edge localized mode (ELM) density transients, and as an L-H transition monitor. The ITER low field side reflectometer system will measure both core and edge quantities using multiple antenna arrays spanning frequency ranges of 15-155 GHz for the O-mode system and 55-220 GHz for the X-mode system. Optimization studies using the GENRAY ray-tracing code have been done for edge and core measurements. The reflectometer launchers will utilize the HE11 mode launched from circular corrugated waveguide. The launched beams are assumed to be Gaussian with a beam waist diameter of 0.643 times the waveguide diameter. Optimum launcher size and placement are investigated by computing the antenna coupling between launchers, assuming the launched and received beams have a Gaussian beam pattern.
Combining configurational energies and forces for molecular force field optimization
Vlcek, Lukas; Sun, Weiwei; Kent, Paul R. C.
2017-10-01
While quantum chemical simulations have been increasingly used as an invaluable source of information for atomistic model development, the high computational expenses typically associated with these techniques often limit thorough sampling of the systems of interest. It is therefore of great practical importance to use all available information as efficiently as possible, and in a way that allows for consistent addition of constraints that may be provided by macroscopic experiments. Here we propose a simple approach that combines information from configurational energies and forces generated in a molecular dynamics simulation to increase the effective number of samples. Subsequently, this information is used to optimize a molecular force field by minimizing the statistical distance similarity metric. We illustrate the methodology on an example of a trajectory of configurations generated in equilibrium molecular dynamics simulations of argon and water and compare the results with those based on the force matching method.
Optimizing direct intense-field laser acceleration of ions
Energy Technology Data Exchange (ETDEWEB)
Harman, Zoltan [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); ExtreMe Matter Institute EMMI, Planckstrasse 1, D-64291 Darmstadt (Germany); Salamin, Yousef I. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Department of Physics, American University of Sharjah, POB 26666, Sharjah (United Arab Emirates); Galow, Benjamin J.; Keitel, Christoph H. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)
2011-11-15
The dynamics of ion acceleration in tightly focused laser beams is investigated in relativistic simulations. Studies are performed to find the optimal parameters which maximize the energy gain, beam quality, and flux. The exit ionic kinetic energy and its uncertainty are improved and the number of accelerated particles is increased by orders of magnitude over our earlier results, especially when working with a longer laser wavelength. Laser beams of powers of 0.1-10 petawatts and focused to subwavelength spot radii are shown to directly accelerate protons and bare nuclei of helium, carbon, and oxygen from a few to several hundred MeV/nucleon. Variation of the volume of the initial ionic ensemble, as well as the introduction of a pulse shape on the laser fields, have been investigated and are shown to influence the exit particle kinetic energies only slightly.
An optimal algorithm based on extended kalman filter and the data fusion for infrared touch overlay
Zhou, AiGuo; Cheng, ShuYi; Pan, Qiang Biao; Sun, Dong Yu
2016-01-01
Current infrared touch overlay has problems on the touch point recognition which bring some burrs on the touch trajectory. This paper uses the target tracking algorithm to improve the recognition and smoothness of infrared touch overlay. In order to deal with the nonlinear state estimate problem for touch point tracking, we use the extended Kalman filter in the target tracking algorithm. And we also use the data fusion algorithm to match the estimate value with the original target trajectory. The experimental results of the infrared touch overlay demonstrate that the proposed target tracking approach can improve the touch point recognition of the infrared touch overlay and achieve much smoother tracking trajectory than the existing tracking approach.
Optimal filtering of dynamics in short-time features for music organization
DEFF Research Database (Denmark)
Arenas-García, Jerónimo; Larsen, Jan; Hansen, Lars Kai
2006-01-01
proof-of-concept, where an altosax with and without vibrato is modelled. A more complex \\$11\\$ music genre classification setup is also investigated to illustrate the robustness and validity of the proposed method on larger datasets. Both experiments showed the good properties of our method, as well...... as superior performance when compared to a fixed filter bank approach suggested previously in the MIR literature. We think that the proposed method is a natural step towards a customized MIR application that generalizes well to a wide range of different music organization tasks.......There is an increasing interest in customizable methods for organizing music collections. Relevant music characterization can be obtained from short-time features, but it is not obvious how to combine them to get useful information. In this work, a novel method, denoted as the Positive Constrained...
Jettanasen, C.; Ngaopitakkul, A.
2010-10-01
Conducted electromagnetic interference (EMI) generated by PWM inverter-fed induction motor drive systems, which are currently widely used in many industrial and/or avionic applications, causes severe parasitic current problems, especially at high frequencies (HF). These restrict power electronic drive's evolution. In order to reduce or minimize these EMI problems, several techniques can be applied. In this paper, insertion of an optimized passive EMI filter is proposed. This filter is optimized by taking into account real impedances of each part of a considered AC motor drive system contrarily to commercial EMI filters designed by considering internal impedance of disturbance source and load, equal to 50Ω. Employing the latter EMI filter would make EMI minimization less effective. The proposed EMI filter optimization is mainly dedicated to minimize common mode (CM) currents due to its most dominant effects in this kind of system. The efficiency of the proposed optimization method using two-port network approach is deduced by comparing the minimized CM current spectra to an applied normative level (ex. DO-160D in aeronautics).
Nenchev, D N; Miyamoto, Y; Iribe, H; Takeuchi, K; Sato, D
2016-01-01
This paper introduces the notion of a reactionless synergy: a postural variation for a specific motion pattern/strategy, whereby the movements of the segments do not alter the force/moment balance at the feet. Given an optimal initial posture in terms of stability, a reactionless synergy can ensure optimality throughout the entire movement. Reactionless synergies are derived via a dynamical model wherein the feet are regarded to be unfixed. Though in contrast with the conventional fixed-feet models, this approach has the advantage of exhibiting the reactions at the feet explicitly. The dynamical model also facilitates a joint-space decomposition scheme yielding two motion components: the reactionless synergy and an orthogonal complement responsible for the dynamical coupling between the feet and the support. Since the reactionless synergy provides the basis (a feedforward control component) for optimal balance control, it may play an important role when evaluating balance abnormalities or when assessing optimality in balance control. We show how to apply the proposed method for analysis of motion capture data obtained from three voluntary movement patterns in the sagittal plane: squat, sway, and forward bend.
Institute of Scientific and Technical Information of China (English)
LAI Rui-xun; FANG Hong-wei; HE Guo-jian; YU Xin; YANG Ming; WANG Ming
2013-01-01
In this paper,both state variables and parameters of one-dimensional open channel model are estimated using a framework of the Ensemble Kalman Filter (EnKF).Compared with observation,the predicted accuracy of water level and discharge are improved while the parameters of the model are identified simultaneously.With the principles of the EnKF,a state-space description of the Saint-Venant equation is constructed by perturbing the measurements with Gaussian error distribution.At the same time,the roughness,one of the key parameters in one-dimensional open channel,is also considered as a state variable to identify its value dynamically.The updated state variables and the parameters are then used as the initial values of the next time step to continue the assimilation process.The usefulness and the capability of the dual EnKF are demonstrated in the lower Yellow River during the water-sediment regulation in 2009.In the optimization process,the errors between the prediction and the observation are analyzed,and the rationale of inverse roughness is discussed.It is believed that (1) the flexible approach of the dual EnKF can improve the accuracy of predicting water level and discharge,(2) it provides a probabilistic way to identify the model error which is feasible to implement but hard to handle in other filter systems,and (3) it is practicable for river engineering and management.
Nonlinear approach for oil field optimization based on gas lift optimization
Energy Technology Data Exchange (ETDEWEB)
Khamehchi, Ehsan; Rashidi, Fariborz [Amirkabir Univ. of Technology, Tehran (Iran). Faculty of Chemical Engineering; Karimi, Behrooz [Amirkabir Univ. of Technology, Tehran (Iran). Faculty of Industrial Engineering; Pourafshary, Peyman [Tehran Univ. (Iran). Petroleum Engineering Inst.
2009-12-15
When the initial energy of a virgin reservoir is not sufficient or when this energy falls below a certain limit after a production history, the production rates won't be able to meet economic margins. It is then time for artificial lift methods to come to aid. Among which, gas lift is the most commonly used scenario. Being somehow an ancient tool with an age of over a century, gas lift is though still a challenging problem when overall optimization is the concern. When the injection gas is of limited supply the problem is finding the best gas allocation scheme. However there are ever more cases emerging in certain geographic localities where the gas supplies are usually unlimited. The optimization problem then totally relates to the wellbore and completion string and fully engages with multiphase flow concepts. In the present study an intelligent genetic algorithm has been developed to simultaneously optimize all role playing factors, namely gas injection rate, injection depth and tubing diameter towards the maximum oil production rate with the water cut and injection pressure as the restrictions. The computations and real field data are mutually compared. (orig.)
Directory of Open Access Journals (Sweden)
Rabindra Kumar Sahu
2015-06-01
Full Text Available In this paper, Differential Evolution (DE optimized fuzzy PID controller with derivative Filter (PIDF is proposed for Load Frequency Control (LFC of a deregulated power system with multi-source power generation and interconnected via parallel AC/DC transmission links. To get an accurate insight of the LFC problem, important physical constraints such as time delay and GRC are considered. The performance of proposed controller is evaluated at all possible power transactions that take place in a deregulated power market. The improvement in dynamic performance of the power system with DC link in parallel with AC tie-line is also assessed. Further, sensitivity analysis is performed by varying the system parameters and operating load conditions from their nominal values. It is observed from the simulation results that the optimum gains of the proposed controller need not be reset even if the system is subjected to wide variation in loading condition and system parameters.
Energy Technology Data Exchange (ETDEWEB)
Trindade, Cassia; Silva, Leonardo P.; Martins, Lais P.; Garcia, Paulo L.; Santos, Maira R.; Bastista, Delano V.S.; Vieira, Anna Myrian M.T.L.; Rocha, Igor M., E-mail: cassiatr@gmail.com [Instituto Nacional de Cancer (INCA), Rio de Janeiro, RJ (Brazil)
2012-12-15
The radiotherapy has been used in a wild scale in breast cancer treatment. With this high demand, new technologies have been developed to improve the dose distribution in the target while reducing the dose delivered in critical organs. In this study, performed with one clinical case, three planning were done for comparison: 3D technique with dynamic filter, 3D with field-in-field technique (forward-planned IMRT) and 3D technique using electronic compensator (ECOMP). The planning were done with a 6MV photon beam using the Eclipse software, version 8.6 (Varian Medical Systems). The PTV was drawn covering the whole breast and the critical organs were: the lung on the irradiated side, the heart, the contralateral breast and the anterior descending coronary artery (LAD). The planning using the compensator technique permitted more homogeneous dose distribution in the target volume. The V20 value of the lung on the irradiated side was 8,3% for the electronic compensator technique, 8,9% for the field-in-field technique and 8,2% for the dynamic filter technique. For the heart the dose range was 15.7 - 139.9 cGy, 16.3 - 148.4 cGy for the dynamic filter technique and 19.6 - 157.0 cGy for the field-in-field technique. The dose gradient was 11% with compensator electronic, 15% dynamic filter technique and 13% with field-in-field. The application of electronic technique in breast cancer treatment allows better dose distribution while reduces dose in critical organs, but in the same time requires a quality assurance. (author)
He, L.; Chen, J. M.; Liu, J.; Mo, G.; Zhen, T.; Chen, B.; Wang, R.; Arain, M.
2013-12-01
Terrestrial ecosystem models have been widely used to simulate carbon, water and energy fluxes and climate-ecosystem interactions. In these models, some vegetation and soil parameters are determined based on limited studies from literatures without consideration of their seasonal variations. Data assimilation (DA) provides an effective way to optimize these parameters at different time scales . In this study, an ensemble Kalman filter (EnKF) is developed and applied to optimize two key parameters of an ecosystem model, namely the Boreal Ecosystem Productivity Simulator (BEPS): (1) the maximum photosynthetic carboxylation rate (Vcmax) at 25 °C, and (2) the soil water stress factor (fw) for stomatal conductance formulation. These parameters are optimized through assimilating observations of gross primary productivity (GPP) and latent heat (LE) fluxes measured in a 74 year-old pine forest, which is part of the Turkey Point Flux Station's age-sequence sites. Vcmax is related to leaf nitrogen concentration and varies slowly over the season and from year to year. In contrast, fw varies rapidly in response to soil moisture dynamics in the root-zone. Earlier studies suggested that DA of vegetation parameters at daily time steps leads to Vcmax values that are unrealistic. To overcome the problem, we developed a three-step scheme to optimize Vcmax and fw. First, the EnKF is applied daily to obtain precursor estimates of Vcmax and fw. Then Vcmax is optimized at different time scales assuming fw is unchanged from first step. The best temporal period or window size is then determined by analyzing the magnitude of the minimized cost-function, and the coefficient of determination (R2) and Root-mean-square deviation (RMSE) of GPP and LE between simulation and observation. Finally, the daily fw value is optimized for rain free days corresponding to the Vcmax curve from the best window size. The optimized fw is then used to model its relationship with soil moisture. We found that
2015-08-27
designing new filters and mathematical analysis of their properties. In particular, we derived a closed formulation for convolution of SIAC kernels with...designing new filters and mathematical analysis of their properties. In particular, we derived a closed formulation for convolution of SIAC kernels ...content of the report. The form of entry is the last name, first name, middle initial, and additional qualifiers separated by commas, e.g. Smith
Long-term field-scale experiment on using lime filters in an agricultural catchment.
Kirkkala, Teija; Ventelä, Anne-Mari; Tarvainen, Marjo
2012-01-01
The River Yläneenjoki catchment in southwest Finland is an area with a high agricultural nutrient load. We report here on the nutrient removal performance of three on-site lime-sand filters (F1, F2, and F3), established within or on the edge of the buffer zones. The filters contain burnt lime (CaO) or spent lime [CaO, Ca(OH), and CaCO]. Easily soluble lime results in a high pH level (>11) and leads to an efficient precipitation of soluble phosphorus (P) from the runoff. Water samples were taken from the inflow and outflow of each site in different hydrological situations. The length of the monitoring period was 4 yr for F1, 6 yr for F2, and 1.5 yr for F3. F1 and F2 significantly reduced the suspended solids (SS), total P (PTOT), and dissolved reactive P (DRP) in the treated water. The proportional reduction (%) varied but was usually clearly positive. Filter F3 was divided into two equal parts, one containing burnt lime and the other spent lime. Both filter parts removed PTOT and SS efficiently from the water; the burnt-lime part also removed DRP. The mixed-lime part removed DRP for a year, but then the efficiency decreased. The effect of filters on nitrogen compounds varied. We conclude that sand filters incorporating lime can be used together with buffer zones to reduce both P and SS load to watercourses.
Designing spectrum-splitting dichroic filters to optimize current-matched photovoltaics.
Miles, Alexander; Cocilovo, Byron; Wheelwright, Brian; Pan, Wei; Tweet, Doug; Norwood, Robert A
2016-03-10
We have developed an approach for designing a dichroic coating to optimize performance of current-matched multijunction photovoltaic cells while diverting unused light. By matching the spectral responses of the photovoltaic cells and current matching them, substantial improvement to system efficiencies is shown to be possible. A design for use in a concentrating hybrid solar collector was produced by this approach, and is presented. Materials selection, design methodology, and tilt behavior on a curved substrate are discussed.
Nere, Nandkishor K; Allen, Kimberley C; Marek, James C; Bordawekar, Shailendra V
2012-10-01
Drying an early stage active pharmaceutical ingredient candidate required excessively long cycle times in a pilot plant agitated filter dryer. The key to faster drying is to ensure sufficient heat transfer and minimize mass transfer limitations. Designing the right mixing protocol is of utmost importance to achieve efficient heat transfer. To this order, a composite model was developed for the removal of bound solvent that incorporates models for heat transfer and desolvation kinetics. The proposed heat transfer model differs from previously reported models in two respects: it accounts for the effects of a gas gap between the vessel wall and solids on the overall heat transfer coefficient, and headspace pressure on the mean free path length of the inert gas and thereby on the heat transfer between the vessel wall and the first layer of solids. A computational methodology was developed incorporating the effects of mixing and headspace pressure to simulate the drying profile using a modified model framework within the Dynochem software. A dryer operational protocol was designed based on the desolvation kinetics, thermal stability studies of wet and dry cake, and the understanding gained through model simulations, resulting in a multifold reduction in drying time.
Doll, Ulrich; Burow, Eike; Beversdorff, Manfred; Stockhausen, Guido; Willert, Christian; Morsbach, Christian; Schlüß, Daniel; Franke, Martin
2015-01-01
The flow field of a Ranque-Hilsch vortex tube is characterized experimentally. Firstly conventional probe based technology is used in order to measure inlet and outlet temperatures as well as to acquire temporally resolved wall pressure data over a wide range of operating conditions. Secondly the filtered Rayleigh scattering technique is employed in order to gather detailed temporally averaged planar information on the vortex tube’s flow topology. These measurements form the basis of a detail...
Bruin, de S.; Lerink, P.; Riviere, la I.J.; Vanmeulebrouk, B.
2014-01-01
This paper describes a geo-spatial arable field optimization service (GAOS) and an assessment of users' experiences after three years of experimental operation. The service was developed in close cooperation with farmers. It allows farmers to optimize the locations of tracks within their fields, exp
Field emission from optimized structure of carbon nanotube field emitter array
Energy Technology Data Exchange (ETDEWEB)
Chouhan, V., E-mail: vchouhan@post.kek.jp, E-mail: vijaychouhan84@gmail.com [School of High Energy Accelerator, The Graduate University for Advanced Studies, Tsukuba 305-0801 (Japan); Noguchi, T. [High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan); Kato, S. [School of High Energy Accelerator, The Graduate University for Advanced Studies, Tsukuba 305-0801 (Japan); High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan)
2016-04-07
The authors report a detail study on the emission properties of field emitter array (FEA) of micro-circular emitters of multiwall carbon nanotubes (CNTs). The FEAs were fabricated on patterned substrates prepared with an array of circular titanium (Ti) islands on titanium nitride coated tantalum substrates. CNTs were rooted into these Ti islands to prepare an array of circular emitters. The circular emitters were prepared in different diameters and pitches in order to optimize their structure for acquiring a high emission current. The pitch was varied from 0 to 600 μm, while a diameter of circular emitters was kept constant to be 50 μm in order to optimize a pitch. For diameter optimization, a diameter was changed from 50 to 200 μm while keeping a constant edge-to-edge distance of 150 μm between the circular emitters. The FEA with a diameter of 50 μm and a pitch of 120 μm was found to be the best to achieve an emission current of 47 mA corresponding to an effective current density of 30.5 A/cm{sup 2} at 7 V/μm. The excellent emission current was attributed to good quality of CNT rooting into the substrate and optimized FEA structure, which provided a high electric field on a whole circular emitter of 50 μm and the best combination of the strong edge effect and CNT coverage. The experimental results were confirmed with computer simulation.
Optimal information transfer in enzymatic networks: A field theoretic formulation
Samanta, Himadri S.; Hinczewski, Michael; Thirumalai, D.
2017-07-01
Signaling in enzymatic networks is typically triggered by environmental fluctuations, resulting in a series of stochastic chemical reactions, leading to corruption of the signal by noise. For example, information flow is initiated by binding of extracellular ligands to receptors, which is transmitted through a cascade involving kinase-phosphatase stochastic chemical reactions. For a class of such networks, we develop a general field-theoretic approach to calculate the error in signal transmission as a function of an appropriate control variable. Application of the theory to a simple push-pull network, a module in the kinase-phosphatase cascade, recovers the exact results for error in signal transmission previously obtained using umbral calculus [Hinczewski and Thirumalai, Phys. Rev. X 4, 041017 (2014), 10.1103/PhysRevX.4.041017]. We illustrate the generality of the theory by studying the minimal errors in noise reduction in a reaction cascade with two connected push-pull modules. Such a cascade behaves as an effective three-species network with a pseudointermediate. In this case, optimal information transfer, resulting in the smallest square of the error between the input and output, occurs with a time delay, which is given by the inverse of the decay rate of the pseudointermediate. Surprisingly, in these examples the minimum error computed using simulations that take nonlinearities and discrete nature of molecules into account coincides with the predictions of a linear theory. In contrast, there are substantial deviations between simulations and predictions of the linear theory in error in signal propagation in an enzymatic push-pull network for a certain range of parameters. Inclusion of second-order perturbative corrections shows that differences between simulations and theoretical predictions are minimized. Our study establishes that a field theoretic formulation of stochastic biological signaling offers a systematic way to understand error propagation in
Simulation and Optimization of Silicon Solar Cell Back Surface Field
Directory of Open Access Journals (Sweden)
Souad TOBBECHE
2015-11-01
Full Text Available In this paper, TCAD Silvaco (Technology Computer Aided Design software has been used to study the Back Surface Field (BSF effect of a p+ silicon layer for a n+pp+ silicon solar cell. To study this effect, the J-V characteristics and the external quantum efficiency (EQE are simulated under AM 1.5 illumination for two types of cells. The first solar cell is without BSF (n+p structure while the second one is with BSF (n+pp+ structure. The creation of the BSF on the rear face of the cell results in efficiency h of up to 16.06% with a short-circuit current density Jsc = 30.54 mA/cm2, an open-circuit voltage Voc = 0.631 V, a fill factor FF = 0.832 and a clear improvement of the spectral response obtained in the long wavelengths range. An electric field and a barrier of potential are created by the BSF and located at the junction p+/p with a maximum of 5800 V/cm and 0.15 V, respectively. The optimization of the BSF layer shows that the cell performance improves with the p+ thickness between 0.35 – 0.39 µm, the p+ doping dose is about 2 × 1014 cm-2, the maximum efficiency up to 16.19 %. The cell efficiency is more sensitive to the value of the back surface recombination velocity above a value of 103 cm/s in n+p than n+pp+ solar cell.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9565
Energy Technology Data Exchange (ETDEWEB)
Reyes, Luis M.G.; Almeida, Adelaide de [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Dept. de Fisica e Matematica
2001-07-01
The signal to noise ratio (S/N) of radiographic film images may be optimized if the thicknesses and atomic composition of the structures to be analyzed are known. With specifications and a knowledge of the interaction of photons with the materials, the photon energy for maximum contrast may be determined. We propose a K-edge filter in addition to the normal aluminum filter, to reduce the dose to the patient by the transmission of a narrow spectrum of photons with energies to optimize the image contrast. The optimum photon energy to obtain the best contrast between dental pulp and dentine and between dentine and dental enamel was determined to be 29-34 and 22-26 keV respectively. The filter material, which closely approximates these spectra, is made of Ce (Z=58) whose thickness is shown do depend on the parameters of the X-ray generator. (author)
Neutron spin filter based on optically polarized sup 3 He in a near-zero magnetic field
Skoy, V R; Sorokin, V N; Kolachevsky, N N; Sobelman, I I; Sermyagin, A V
2003-01-01
A test of polarization of sup 3 He nuclei via spin-exchange collisions with optically pumped rubidium atoms in an extremely low applied magnetic field was carried out. Permalloy magnetic shields were used to prevent a fast relaxation of sup 3 He polarization owing to the inhomogeneity of a surrounding magnetic field. The whole installation was placed at the neutron beam line of the IBR-30 facility, and used as a neutron spin filter. Thus, a prototype of new design of neutron polarizer was introduced. We intend to apply this experience for the full-scale KaTRIn facility to test the time reversal violation in neutron-nuclear reactions.
Neutron spin filter based on optically polarized {sup 3}He in a near-zero magnetic field
Energy Technology Data Exchange (ETDEWEB)
Skoy, V.R. E-mail: skoy@nf.jinr.ru; Prokofichev, Yu.V.; Sorokin, V.N.; Kolachevski, N.N.; Sobelman, I.I.; Sermyagin, A.V
2003-04-01
A test of polarization of {sup 3}He nuclei via spin-exchange collisions with optically pumped rubidium atoms in an extremely low applied magnetic field was carried out. Permalloy magnetic shields were used to prevent a fast relaxation of {sup 3}He polarization owing to the inhomogeneity of a surrounding magnetic field. The whole installation was placed at the neutron beam line of the IBR-30 facility, and used as a neutron spin filter. Thus, a prototype of new design of neutron polarizer was introduced. We intend to apply this experience for the full-scale KaTRIn facility to test the time reversal violation in neutron-nuclear reactions.
Optimizing single mode robustness of the distributed modal filtering rod fiber amplifier
DEFF Research Database (Denmark)
Jørgensen, Mette Marie; Petersen, Sidsel Rübner; Laurila, Marko;
2012-01-01
can be compensated during the fiber draw. Design optimization of the SM bandwidth of the DMF rod fiber is presented. Analysis of band gap properties results in a fourfold increase of the SM bandwidth compared to previous results, achieved by utilizing the first band of cladding modes, which can cover......High-power fiber amplifiers for pulsed applications require large mode area (LMA) fibers having high pump absorption and near diffraction limited output. Photonic crystal fibers allow realization of short LMA fiber amplifiers having high pump absorption through a pump cladding that is decoupled...... a large fraction of the Yb emission band including wavelengths of 1030 nm and 1064 nm. Design parameters tolerating refractive index fabrication uncertainties of ± 10-4 are targeted to yield stable SM bandwidths....
DEFF Research Database (Denmark)
Jørgensen, Mette Marie; Petersen, Sidsel Rübner; Laurila, Marko;
2012-01-01
. Large preform tolerances are compensated during the fiber draw resulting in ultra low NA fibers with very large cores. In this paper, design optimization of the SM bandwidth of the DMF rod fiber is presented. Analysis of band gap properties results in a fourfold increase of the SM bandwidth compared......High-power fiber amplifiers for pulsed applications require large mode area (LMA) fibers having high pump absorption and near diffraction limited output. This improves the limiting factor of nonlinear effects, while maintaining good beam quality. Photonic crystal fibers allow realization of short...... to previous results, achieved by utilizing the first band of cladding modes. This covers of a large fraction of the Yb emission band, where wavelengths of 1030 nm and 1064 nm can be included....
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.
CSIR Research Space (South Africa)
Salmon, BP
2012-07-01
Full Text Available In this paper the Bias Variance Search Algorithm is proposed as an algorithm to optimize a candidate set of initial parameters for an Extended Kalman filter (EKF). The search algorithm operates on a Bias Variance Equilibrium Point criterion...
Öksüzoglu, R. Mustafa; Schug, Christoph; York, Brian
2004-09-01
The influence of unidirectional field annealing (UDA) and subsequent stress annealing (SA) on the structure and magnetic response of PtMn bottom spin-filter spin-valve sensors with a NiFeCr/NiFe seed layer was investigated. A time constant of 1.17 h for the FCC-FCT phase transition of the PtMn layer was obtained upon UDA at 265°C in an external magnet field of 13 kOe, which is consistent with 1.1 h observed for the GMR. A lower time constant of 0.7 h was determined for the exchange interaction field. The SA with similar conditions as in the manufacturing environment leads to a UDA time-dependent alteration of sensor performance. A SA up to 38 h causes a GMR value reduction, which becomes more pronounced with increasing UDA duration prior to SA. Furthermore, SA causes a progressive oxidation of the Ta cap layer; in contrast, the exchange field remains nearly unaffected, particularly for the sensors with 5 or 6 h UDA. From the point view of application, an UDA treatment of (5-6) h yields the optimal sensor performance for the finished read-write head.
Directory of Open Access Journals (Sweden)
Germán Gálvez-García
2016-03-01
Full Text Available During the past decades, animal and human physiological studies have suggested that subcortical structures that are part of the extrageniculate pathways have an important role to play in the attentive selection of targets and the filtering of distractors. However, not much has been done to investigate the filtering of distractors in purely behavioural experiments through cues that might reveal extrageniculate functions, such as the asymmetry in performance between the nasal and the temporal visual fields. Here, under monocular conditions, participants viewed laterally and tachistoscopically presented sets of visual stimuli and were required to decide whether a target was present in the set or not. The manipulation of attention demands was achieved by varying the degree of spatial organization of the stimuli. A temporal field advantage in detection accuracy was found, and was observed only for disorganised sets of stimuli, that is, when demands on attention were greater. Furthermore, this pattern was found only for stimuli projected to the right hemisphere. The results suggest that the extrageniculate pathways of the right hemisphere in humans are involved in filtering out distractors. They are discussed in light of findings and theories about extrageniculate mediation of selective attention.
Tan, S; Roth, B J; Wikswo, J P
1990-07-01
We extend our theoretical model based on spatial filtering to determine the ability of a SQUID magnetometer to resolve 2 localized current sources in the brain. We find that in order to resolve 2 separated but coaxial cortical sources, the source-to-pickup coil distance must be comparable to the distance between the 2 sources. The size of the current sources affects the resolving power of a magnetometer, but an anisotropy of 3 in the cortical tissue does not produce a significant effect. The model also provides a solution of the inverse calculation, either to reconstruct the original current source distribution from the measured magnetic field, or to continue the field at the magnetometer inward towards the sources. Both the inverse and inward calculations are limited by the fact that the inverse filter function serves as a high-pass filter, which leads to instabilities at high spatial frequencies, particularly in the presence of noise. The instabilities can be minimized by choosing an appropriate window to attenuate the noise, but this in turn reduces the spatial resolution.
Akkaya, Gulizar Kurtoglu; Sekman, Elif; Top, Selin; Sagir, Ece; Bilgili, Mehmet Sinan; Guvenc, Senem Yazici
2017-03-09
The aim of this study is to investigate filterability enhancement of activated sludge supplied form a full-scale leachate treatment plant by applying DC electric field while keeping the biological operational conditions in desirable range. The activated sludge samples were received from the nitrification tank in the leachate treatment plant of Istanbul's Odayeri Sanitary Landfill Site. Experimental sets were conducted as laboratory-scale batch studies and were duplicated for 1A, 2A, 3A, 4A, and 5A of electrical currents and 2, 5, 10, 15, and 30 min of exposure times under continuous aeration. Physicochemical parameters such as temperature, pH, and oxidation reduction potential in the mixture right after each experimental set and biochemical parameters such as chemical oxygen demand, total phosphorus, and ammonia nitrogen in supernatant were analyzed to define the sets that remain in the range of ideal biological operational conditions. Later on, sludge filterability properties such as capillary suction time, specific resistance to filtration, zeta potential, and particle size were measured for remaining harmless sets. Additionally, cost analyses were conducted in respect to energy and electrode consumptions. Application of 2A DC electric field and 15-min exposure time was found to be the most favorable conditions to enhance filterability of the landfill leachate-activated sludge.
Energy Technology Data Exchange (ETDEWEB)
Ueno, A., E-mail: akira.ueno@j-parc.jp; Koizumi, I.; Ohkoshi, K.; Ikegami, K.; Takagi, A.; Yamazaki, S.; Oguri, H. [J-PARC Center, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195 (Japan)
2014-02-15
The prototype rf-driven H{sup −} ion-source with a nickel plated oxygen-free-copper (OFC) plasma chamber, which satisfies the Japan Proton Accelerator Research Complex (J-PARC) 2nd stage requirements of a H{sup −} ion beam current of 60 mA within normalized emittances of 1.5 π mm mrad both horizontally and vertically, a flat top beam duty factor of 1.25% (500 μs × 25 Hz) and a life-time of more than 50 days, was reported at the 3rd international symposium on negative ions, beams, and sources (NIBS2012). The experimental results of the J-PARC ion source with a plasma chamber made of stainless-steel, instead of nickel plated OFC used in the prototype source, are presented in this paper. By comparing these two sources, the following two important results were acquired. One was that the about 20% lower emittance was produced by the rather low plasma electrode (PE) temperature (T{sub PE}) of about 120 °C compared with the typically used T{sub PE} of about 200 °C to maximize the beam current for the plasma with the abundant cesium (Cs). The other was that by using the rod-filter magnets with a gap at each center and tuning the gap-lengths, the filter-field was optimized and the rf-power necessary to produce the J-PARC required H{sup −} ion beam current was reduced typically 18%. The lower rf-power also decreases the emittances.
Switching Optimization of PET Prepolymers Filter%聚酯装置中预聚物过滤器切换方法的优化
Institute of Scientific and Technical Information of China (English)
王建华; 孟庆吉; 罗加成; 瞿林飞; 李岗
2012-01-01
预聚物过滤器安装在缩聚釜Ⅱ和终聚釜之间,起到初步过滤没有参加反应的大分子和凝集粒子的作用.探讨了中纺院五釜聚酯装置中预聚物过滤器切换方法的优化.通过优化,减少了预聚物过滤器的清洗工作量,节省了滤芯使用成本,同时确保在一个检修周期内,装置能够“安、稳、长、满、优”地运行.%The prepolymers filter is installed between the polycondensation reactor II and final polyconden-sation reactor to stop the macromolecules and agglutination particles which are did not reacted. The switching optimization of the China Textile Academy five-reactor device prepolymer filter is discussed. Through the optimization of the prepolymer filter switching method, the prepolymers filter cleaning workload is reduced, the cost of the filter is saved, so as to ensure that the device in an overhaul cycle "security, stability, long, full, excellent" run.
基于粒子群优化算法的模拟滤波器设计%Design of Analog Filter Based on Particle Swarm Optimization Algorithm
Institute of Scientific and Technical Information of China (English)
李鹏; 马红梅; 张旭珍
2011-01-01
采用传统的网络综合法设计计波器存在带宽不精确及阻带衰减过小的问题,为此,提出一种基于粒子群优化算法的无源模拟滤波器优化设计方法.在网络综合法设计的滤波器电路基础上,利用粒子群优化算法对滤波器的整个参数空间进行高效并行搜索直到获得最优的参数值.实例表明,采用该方法设计的滤波器带宽更加准确,且具有更加陡峭的阻带衰减.%As for the problem of the filter's bandwidth imprecision and stop-band attenuation too small, a passive analog filter optimization design method is proposed based on the Particle Swarm Optimization(PSO) algorithm.The filter is designed by the network synthesis design method, and it optimizes the circuit's parameters in the whole parameters space effectively and globally by PSO until gain the best parameters.This method can improve the filter's bandwidth imprecision and the high stop-band suppression.
Tseng, Chien-Hsun
2015-02-01
The technique of multidimensional wave digital filtering (MDWDF) that builds on traveling wave formulation of lumped electrical elements, is successfully implemented on the study of dynamic responses of symmetrically laminated composite plate based on the first order shear deformation theory. The philosophy applied for the first time in this laminate mechanics relies on integration of certain principles involving modeling and simulation, circuit theory, and MD digital signal processing to provide a great variety of outstanding features. Especially benefited by the conservation of passivity gives rise to a nonlinear programming problem (NLP) for the issue of numerical stability of a MD discrete system. Adopting the augmented Lagrangian genetic algorithm, an effective optimization technique for rapidly achieving solution spaces of NLP models, numerical stability of the MDWDF network is well received at all time by the satisfaction of the Courant-Friedrichs-Levy stability criterion with the least restriction. In particular, optimum of the NLP has led to the optimality of the network in terms of effectively and accurately predicting the desired fundamental frequency, and thus to give an insight into the robustness of the network by looking at the distribution of system energies. To further explore the application of the optimum network, more numerical examples are engaged in efforts to achieve a qualitative understanding of the behavior of the laminar system. These are carried out by investigating various effects based on different stacking sequences, stiffness and span-to-thickness ratios, mode shapes and boundary conditions. Results are scrupulously validated by cross referencing with early published works, which show that the present method is in excellent agreement with other numerical and analytical methods.
Thiboult, A.; Anctil, F.
2015-10-01
Forecast reliability and accuracy is a prerequisite for successful hydrological applications. This aim may be attained by using data assimilation techniques such as the popular Ensemble Kalman filter (EnKF). Despite its recognized capacity to enhance forecasting by creating a new set of initial conditions, implementation tests have been mostly carried out with a single model and few catchments leading to case specific conclusions. This paper performs an extensive testing to assess ensemble bias and reliability on 20 conceptual lumped models and 38 catchments in the Province of Québec with perfect meteorological forecast forcing. The study confirms that EnKF is a powerful tool for short range forecasting but also that it requires a more subtle setting than it is frequently recommended. The success of the updating procedure depends to a great extent on the specification of the hyper-parameters. In the implementation of the EnKF, the identification of the hyper-parameters is very unintuitive if the model error is not explicitly accounted for and best estimates of forcing and observation error lead to overconfident forecasts. It is shown that performance are also related to the choice of updated state variables and that all states variables should not systematically be updated. Additionally, the improvement over the open loop scheme depends on the watershed and hydrological model structure, as some models exhibit a poor compatibility with EnKF updating. Thus, it is not possible to conclude in detail on a single ideal manner to identify an optimal implementation; conclusions drawn from a unique event, catchment, or model are likely to be misleading since transferring hyper-parameters from a case to another may be hazardous. Finally, achieving reliability and bias jointly is a daunting challenge as the optimization of one score is done at the cost of the other.
Bifurcations of optimal vector fields in the shallow lake model
T. Kiseleva; F.O.O. Wagener
2010-01-01
The solution structure of the set of optimal solutions of the shallow lake problem, a problem of optimal pollution management, is studied as we vary the values of the system parameters: the natural resilience, the relative importance of the resource for social welfare and the future discount rate. W
Connolly, Joseph W.; Csank, Jeffrey Thomas; Chicatelli, Amy; Kilver, Jacob
2013-01-01
This paper covers the development of a model-based engine control (MBEC) methodology featuring a self tuning on-board model applied to an aircraft turbofan engine simulation. Here, the Commercial Modular Aero-Propulsion System Simulation 40,000 (CMAPSS40k) serves as the MBEC application engine. CMAPSS40k is capable of modeling realistic engine performance, allowing for a verification of the MBEC over a wide range of operating points. The on-board model is a piece-wise linear model derived from CMAPSS40k and updated using an optimal tuner Kalman Filter (OTKF) estimation routine, which enables the on-board model to self-tune to account for engine performance variations. The focus here is on developing a methodology for MBEC with direct control of estimated parameters of interest such as thrust and stall margins. Investigations using the MBEC to provide a stall margin limit for the controller protection logic are presented that could provide benefits over a simple acceleration schedule that is currently used in traditional engine control architectures.
Janke, Leandro; Leite, Athaydes; Batista, Karla; Weinrich, Sören; Sträuber, Heike; Nikolausz, Marcell; Nelles, Michael; Stinner, Walter
2016-01-01
Different methods for optimization the anaerobic digestion (AD) of sugarcane filter cake (FC) with a special focus on volatile fatty acids (VFA) production were studied. Sodium hydroxide (NaOH) pretreatment at different concentrations was investigated in batch experiments and the cumulative methane yields fitted to a dual-pool two-step model to provide an initial assessment on AD. The effects of nitrogen supplementation in form of urea and NaOH pretreatment for improved VFA production were evaluated in a semi-continuously operated reactor as well. The results indicated that higher NaOH concentrations during pretreatment accelerated the AD process and increased methane production in batch experiments. Nitrogen supplementation resulted in a VFA loss due to methane formation by buffering the pH value at nearly neutral conditions (∼ 6.7). However, the alkaline pretreatment with 6g NaOH/100g FCFM improved both the COD solubilization and the VFA yield by 37%, mainly consisted by n-butyric and acetic acids.
Directory of Open Access Journals (Sweden)
Mohammad Jannati
2014-12-01
Full Text Available Nowadays, Field-Oriented Control (FOC strategies broadly used as a vector based controller for Single-Phase Induction Motors (SPIMs. This paper is focused on Direct Rotor FOC (DRFOC of SPIM. In the proposed technique, transformation matrices are applied in order to control the motor by converting the unbalanced SPIM equations to the balanced equations (in this paper the SPIM with two different stator windings is considered. Besides this control technique, a method for speed estimation of SPIM based on Extended Kalman Filter (EKF to achieve the higher performance of SPIM drive system is presented. Simulation results are provided to demonstrate the high performance of the presented techniques.
Experimental results with an optimized magnetic field configuration for JET breakdown
Albanese, R.; Maviglia, F.; Lomas, P. J.; Manzanares, A.; Mattei, M.; Neto, A.; Rimini, F. G.; de Vries, P. C.; JET-EFDA Contributors,
2012-01-01
Experiments and modelling have been carried out to optimize the magnetic field null during breakdown at JET. Such optimization may prove to be essential for reliable plasma initiation at low voltages, e.g. in ITER where the value of the electric field available will be limited to 0.33 V&
Optimal three-field block-preconditioners for models of coupled magma/mantle dynamics
Rhebergen, Sander; Wathen, Andrew J; Katz, Richard F
2014-01-01
For a prescribed porosity, the coupled magma/mantle flow equations can be formulated as a two field system of equations with velocity and pressure unknowns. Previous work has shown that while optimal preconditioners for the two field formulation can be constructed, the construction of preconditioners that are uniform with respect to model parameters is difficult. This limits the applicability of two field preconditioners in certain regimes of practical interest. We address this issue by reformulating the governing equations as a three field problem, which removes a term that was problematic in the two field formulation in favour of an additional equation for a pressure-like field. For the three-field problem, we develop and analyse new preconditioners and we show numerically that the new three-field preconditioners are optimal in terms of problem size and less sensitive to model parameters compared to the two-field preconditioner. This extends the applicability of optimal preconditioners for coupled mantle/ma...
Using remote sensing images to design optimal field sampling schemes
CSIR Research Space (South Africa)
Debba, Pravesh
2008-08-01
Full Text Available At this presentation, the author discussed a statistical method for deriving optimal spatial sampling schemes. First I focus on ground verification of minerals derived from hyperspectral data. Spectral angle mapper (SAM) and spectral feature fitting...
Isogeometric Analysis for Topology Optimization with a Phase Field Model
2011-09-01
been successfully considered. For example, this is the case for applications in fluid dynamics [1], heat conduction [45], vibration [58], multiphysics...Laboratories SAND2006–2649 (2006). [45] A. Gersborg–Hansen, M.P. Bendsøe and O. Sigmund, Topology optimization of heat conduction problems using the...novel stent platform with drug reservoirs, Med. Eng. Phys. 30 (2008), 1177–1185. [111] Y.M. Xie and G.P. Steven, Evolutionary Structural Optimization
A Study of Optimization of Alpha-Beta-Gamma-Eta Filter for Tracking a High Dynamic Target
Directory of Open Access Journals (Sweden)
Tae-Gweon Jeong
2017-03-01
Full Text Available The tracking filter plays a key role in accurate estimation and prediction of maneuvering vessel’s position and velocity. Different methods are used for tracking. However, the most commonly used method is the Kalman filter and its modifications. The Alpha-Beta-Gamma filter is one of the special cases of the general solution pro-vided by the Kalman filter. It is a third order filter that computes the smoothed estimates of position, velocity and acceleration for the nth observation, and also predicts the next position and velocity. Although found to track a maneuvering target with a good accuracy than the constant velocity, Alpha-Beta filter, the Alpha-Beta-Gamma filter does not perform impressively under high maneuvers such as when the target is undergoing changing accelerations. This study, therefore, aims to track a highly maneuvering target experiencing jerky motions due to changing accelerations. The Alpha-Beta-Gamma filter is extended to include the fourth state that is, constant jerk to correct the sudden change of acceleration in order to improve the filter’s performance. Results obtained from simulations of the input model of the target dynamics under consideration indicate an improvement in performance of the jerky model, Alpha-Beta-Gamma-Eta, algorithm as compared to the constant acceleration model, Alpha-Beta-Gamma in terms of error reduction and stability of the filter during target maneuver.
Energy Technology Data Exchange (ETDEWEB)
Alishayev, M.G.; Rozenberg, M.D.; Teslyuk, Ye.V.
1985-01-01
A description is made of the effect of water injected in large volumes at low temperature on the development indicators and the oil output coefficient, as well as their dependence on the thermal methods of bed modification. An examination was made of the mechanism for displacing oil from the beds during thermal flooding, temperature mode of the bed beyond the displacement front and in those regions where there is no displacement front. Examples are given of determining the filtering indicators and the technical and technological indicators of working in displacement of oil by water.
Well Field Management Using Multi-Objective Optimization
DEFF Research Database (Denmark)
Hansen, Annette Kirstine; Hendricks Franssen, H. J.; Bauer-Gottwein, Peter
2013-01-01
Efficient management of groundwater resources is important because groundwater availability is limited and, locally, groundwater quality has been impaired because of contamination. Here we present a multi-objective optimization framework for improving the management of a water works that operates...... with infiltration basins, injection wells and abstraction wells. The two management objectives are to minimize the amount of water needed for infiltration and to minimize the risk of getting contaminated water into the drinking water wells. The management is subject to a daily demand fulfilment constraint. Two...... optimization results are presented for the Hardhof water works in Zurich, Switzerland. It is found that both methods perform better than the historical management. The constant scheduling performs best in fairly stable conditions, whereas the sequential optimization performs best in extreme situations...
Optimal control of electromagnetic field using metallic nanoclusters
Grigorenko, Ilya; Haas, Stephan; Balatsky, Alexander; Levi, A. F. J.
2008-04-01
The dielectric properties of metallic nanoclusters in the presence of an applied electromagnetic field are investigated using the non-local linear response theory. In the quantum limit we find a nontrivial dependence of the induced field and charge distributions on the spatial separation between the clusters and on the frequency of the driving field. Using a genetic algorithm, these quantum functionalities are exploited to custom-design sub-wavelength lenses with a frequency-controlled switching capability.
Sugawara, Hirotake; Ogino, So
2016-07-01
The electron motion under confronting divergent magnetic fields (CDMFs) applied to inductively coupled plasmas was simulated using a Monte Carlo method. The CDMFs induced by two coaxial dc coils confined electrons in one side of the separatrix of the CDMFs. However, electrons diffused across the separatrix mainly in two ways. One was the displacement of their gyrocenters due to scattering near the outer part of the separatrix. This process tended to occur for high-energy electrons with correspondingly large gyroradii. The other was passage through the weak magnetic field around the center. This process was allowed for low-energy electrons. The position-dependent selectivity about the electron energy was pointed out as a seed property for applications of the separatrix as a magnetic filter or shutter. The mechanism by which the functions of the separatrix emerge was explained from a viewpoint of electron motion under the CDMFs.
Calculation and optimization of stray fields of septum dipole magnets
Holmes, Andrew J T
1976-01-01
A theoretical treatment is described of the external stray field of C- shaped septum magnets, such as those designed for the beam extraction systems of the 400 GeV CERN Super Proton Synchrotron. A special conformal transformation of the magnetic plane yields analytic expressions for the four components of the stray field: the septum- shape field (due to the form of the septum conductor), the edge-effect field (due to the mechanical clearance between septum and yoke), the cooling-duct field (due to the presence of these ducts in the septum), and the magnetomotance field (caused by the ampere-turn losses in the yoke). These expressions can be computed by numerical iteration. The septum-shape field turns out to be opposite in sign to the other three, making possible a criterion which creates a minimal stray field for a given magnetic induction. Plots of calculated and measured stray fields are presented for four prototype septum magnets whose total induction is between 0.38 and 1.41 T. (3 refs).
DEFF Research Database (Denmark)
Jensen, Jesper Rindom; Benesty, Jacob; Christensen, Mads Græsbøll
2013-01-01
In this paper, we introduce a new class of op- timal rectangular filtering matrices for single-channel speech enhancement. The new class of filters exploits the fact that the dimension of the signal subspace is lower than that of the full space. By doing this, extra degrees of freedom...... in the filters, that are otherwise reserved for preserving the signal subspace, can be used for achieving an improved output signal-to-noise ratio (SNR). Moreover, the filters allow for explicit control of the tradeoff between noise reduction and speech distortion via the chosen rank of the signal subspace...... and real signals. The results show a number of interesting things. Firstly, they show how speech distortion can be traded for noise reduction and vice versa in a seamless manner. Moreover, the introduced filter designs are capable of achieving both the upper and lower bounds for the output SNR via...
Filter quality of pleated filter cartridges.
Chen, Chun-Wan; Huang, Sheng-Hsiu; Chiang, Che-Ming; Hsiao, Ta-Chih; Chen, Chih-Chieh
2008-04-01
The performance of dust cartridge filters commonly used in dust masks and in room ventilation depends both on the collection efficiency of the filter material and the pressure drop across the filter. Currently, the optimization of filter design is based only on minimizing the pressure drop at a set velocity chosen by the manufacturer. The collection efficiency, an equally important factor, is rarely considered in the optimization process. In this work, a filter quality factor, which combines the collection efficiency and the pressure drop, is used as the optimization criterion for filter evaluation. Most respirator manufacturers pleat the filter to various extents to increase the filtration area in the limit space within the dust cartridge. Six sizes of filter holders were fabricated to hold just one pleat of filter, simulating six different pleat counts, ranging from 0.5 to 3.33 pleats cm(-1). The possible electrostatic charges on the filter were removed by dipping in isopropyl alcohol, and the air velocity is fixed at 100 cm s(-1). Liquid dicotylphthalate particles generated by a constant output atomizer were used as challenge aerosols to minimize particle loading effects. A scanning mobility particle sizer was used to measure the challenge aerosol number concentrations and size distributions upstream and downstream of the pleated filter. The pressure drop across the filter was monitored by using a calibrated pressure transducer. The results showed that the performance of pleated filters depend not only on the size of the particle but also on the pleat count of the pleated filter. Based on filter quality factor, the optimal pleat count (OPC) is always higher than that based on pressure drop by about 0.3-0.5 pleats cm(-1). For example, the OPC is 2.15 pleats cm(-1) from the standpoint of pressure drop, but for the highest filter quality factor, the pleated filter needed to have a pleat count of 2.65 pleats cm(-1) at particle diameter of 122 nm. From the aspect of
Global optimization of parameters in the reactive force field ReaxFF for SiOH.
Larsson, Henrik R; van Duin, Adri C T; Hartke, Bernd
2013-09-30
We have used unbiased global optimization to fit a reactive force field to a given set of reference data. Specifically, we have employed genetic algorithms (GA) to fit ReaxFF to SiOH data, using an in-house GA code that is parallelized across reference data items via the message-passing interface (MPI). Details of GA tuning turn-ed out to be far less important for global optimization efficiency than using suitable ranges within which the parameters are varied. To establish these ranges, either prior knowledge can be used or successive stages of GA optimizations, each building upon the best parameter vectors and ranges found in the previous stage. We have finally arrive-ed at optimized force fields with smaller error measures than those published previously. Hence, this optimization approach will contribute to converting force-field fitting from a specialist task to an everyday commodity, even for the more difficult case of reactive force fields.
Structure Parameters Optimization of the Filter Core and Numerical Simulation%滤芯结构参数的优化及数值模拟
Institute of Scientific and Technical Information of China (English)
巴鹏; 房元灿; 欧周华; 张鹏飞
2012-01-01
研究液压管路过滤系统褶型不锈钢滤芯的结构参数和压降之间的关系,建立滤芯结构参数和压降之间的数学模型.寻求XYZ-100稀油站所使用的过滤器滤芯的最优结构参数,并用CFD软件FLUENT对理论计算的最优结构参数进行数值模拟,将理论结果和模拟结果进行对比,结果表明:通过理论模型求得的最优结构参数是可行的.%To research relationship of pressure drop with structure parameters of pleated stainless steel filter core of the hydraulic pipelines, a mathematic model between the structure parameters of filter core and pressure drop was constructed. The optimized structure parameters of the filter core for XYZ-100 lubricant machine in the working state were searched, and the optimized structure parameters were simulated with FLUENT software. The calculated values were contrasted with the simulated values. It is shown that the optimized structure parameters calculated by the theoretical model are feasible.
Intrinsic dendritic filtering gives low-pass power spectra of local field potentials
DEFF Research Database (Denmark)
Lindén, Henrik; Pettersen, Klas H; Einevoll, Gaute T
2010-01-01
of contributions to the LFP from a single layer-5 pyramidal neuron and a single layer-4 stellate neuron receiving synaptic input. An intrinsic dendritic low-pass filtering effect of the LFP signal, previously demonstrated for extracellular signatures of action potentials, is seen to strongly affect the LFP power...... spectra, even for frequencies as low as 10 Hz for the example pyramidal neuron. Further, the LFP signal is found to depend sensitively on both the recording position and the position of the synaptic input: the LFP power spectra recorded close to the active synapse are typically found to be less low...... of the observed LFP. Two approximate schemes for calculating the LFP, the dipole approximation and the two-monopole approximation, are tested and found to be potentially useful for translating results from large-scale neural network models into predictions for results from electroencephalographic (EEG...
Mapping of the radiation field of a mammography equipment using molybdenum and rhodium filters
Energy Technology Data Exchange (ETDEWEB)
Barreira, Jacqueline S.; Campos, Daniela; Vivolo, Vitor, E-mail: jacsales@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)
2014-07-01
The use of X rays for diagnostic radiology is very common and important to Medicine, including mammographic diagnosis focusing decreasing of the doses applied to the patients and preserving high quality of the diagnostic image. A quality control program of the irradiation systems it is very necessary. The Instruments Calibration Laboratory (LCI) of IPEN perform calibration in dosemeters used in radiation dosimetry (in diagnostic radiology) for many years. The objective of that paper is determining the point of greatest intensity of the beam issued by the mammography equipment. Exposures were made with filters Rhodium and Molybdenum. That mapping is important before applied a routine quality control program of the mammography equipment and the calibration of instruments in the diagnosis. (author)
基于果蝇优化算法的模拟滤波器设计%Design of Analog Filter Based on Fruit Fly Optimization Algorithm
Institute of Scientific and Technical Information of China (English)
肖正安
2012-01-01
基于粒子群优化算法的无源模拟滤波器优化设计方法容易陷入局部最优,收敛速度慢迭代次数多、运算量大且稳定性不够好。提出果蝇优化算法对滤波器的整个参数空间进行高效并行搜索直到获得最优的参数值,实例仿真表明,采用该方法设计的滤波器在相同的带宽准确度及阻带衰减的情况下,具有更快的运算速度及收敛性能。%The optimum design of passive simulation filters based on Particle Swarm Optimization algorithm has slow convergence velocity and may easily fall into local optimum,more iterative times,large computational complexity,and stability is not good enough.A passive analog filter optimization design method is proposed based on the Fruit Fly Optimization Algorithm（FOA）,and it optimizes the circuit＇s parameters in the whole parameters space effectively and globally by FOA until gain the best parameters.The simulation results on the MATLAB show that our algorithm has global convergence and higher speed of optimization.
Topology Optimization of a High-Temperature Superconducting Field Winding of a Synchronous Machine
DEFF Research Database (Denmark)
Pozzi, Matias; Mijatovic, Nenad; Jensen, Bogi Bech
2013-01-01
genetic algorithm with local optimization search based on on/off sensitivity analysis. The results show an optimal HTS coil distribution, achieving compact designs with a maximum of approximately 22% of the available space for the field winding occupied with HTS tape. In addition, this paper describes......This paper presents topology optimization (TO) of the high-temperature superconductor (HTS) field winding of an HTS synchronous machine. The TO problem is defined in order to find the minimum HTS material usage for a given HTS synchronous machine design. Optimization is performed using a modified...
Mohammed, Ahmed A. K.; Limacher, Peter A.; Ayers, Paul W.
2017-08-01
The finite field method was used to calculate the static first and second hyperpolarizabilities (β and γ) for organic molecules. The dependence of β and γ on the applied electric field strength was investigated and used to determine the optimal field strength for each individual molecule. For γ, we designed a protocol that uses the maximum atomic distance within the molecule along the direction of the applied field to estimate optimal field strengths. However, β is nearly independent of the descriptors we considered, and largely depends on the composition (e.g., the presence of certain functional groups) of the molecule.
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.
Testud, J.; Chong, M.
1983-07-01
This paper is the first of three dealing with the three-dimensional wind field analysis from dual-Doppler radar data. Here we deal with the first step of the analysis which consists in interpolating and filtering the raw radial velocity fields within each coplane (or common plane simultaneously scanned by the two radars). To carry out such interpolation and filtering, a new method is proposed based on the principles of numerical variational analysis described by Sasaki (1970): the `filtered' representation of the observed field should be both `close' to the data points (in a least-squares sense) and verify some imperative of mathematical regularity. Any method for interpolating and smoothing data is inherently a filtering process. The proposed variational method enables this filtering to be controlled. The presented method is developed for any function of two variables but could be extended to the case of three or more variables.Numerical simulations substantiate the theoretically predicted filtering characteristics and show an improvement on other filtering schemes. It is found, compared to the classical filtering using the Cressman weighting function, that the variational method brings a substantial improvement of the gain curve (in the sense of a steeper cut-off), when the `regularity' of the second-order derivatives is imposed. It is worth noting that this improvement is achieved without increasing the computing time. It is also emphasized that an elaborate numerical differentiation scheme should be used to estimate the divergence, otherwise the gain curve for this parameter may be different from that for the Cartesian coplane velocities (which may induce distortion in the final three-dimensional wind field).
Multicomponent seismic noise attenuation with multivariate order statistic filters
Wang, Chao; Wang, Yun; Wang, Xiaokai; Xun, Chao
2016-10-01
The vector relationship between multicomponent seismic data is highly important for multicomponent processing and interpretation, but this vector relationship could be damaged when each component is processed individually. To overcome the drawback of standard component-by-component filtering, multivariate order statistic filters are introduced and extended to attenuate the noise of multicomponent seismic data by treating such dataset as a vector wavefield rather than a set of scalar fields. According to the characteristics of seismic signals, we implement this type of multivariate filtering along local events. First, the optimal local events are recognized according to the similarity between the vector signals which are windowed from neighbouring seismic traces with a sliding time window along each trial trajectory. An efficient strategy is used to reduce the computational cost of similarity measurement for vector signals. Next, one vector sample each from the neighbouring traces are extracted along the optimal local event as the input data for a multivariate filter. Different multivariate filters are optimal for different noise. The multichannel modified trimmed mean (MTM) filter, as one of the multivariate order statistic filters, is applied to synthetic and field multicomponent seismic data to test its performance for attenuating white Gaussian noise. The results indicate that the multichannel MTM filter can attenuate noise while preserving the relative amplitude information of multicomponent seismic data more effectively than a single-channel filter.
Houno, Yuuki; Hishikawa, Toshimitsu; Gotoh, Ken-Ichi; Naitoh, Munetaka; Mitani, Akio; Noguchi, Toshihide; Ariji, Eiichiro; Kodera, Yoshie
2017-09-01
Evaluation of alveolar bone is important in the diagnosis of dental diseases. The periodontal ligament space is difficult to clearly depict in cone-beam computed tomography images because the reconstruction filter conditions during image processing cause image blurring, resulting in decreased spatial resolution. We examined different reconstruction filters to assess their ability to improve spatial resolution and allow for a clearer visualization of the periodontal ligament space. Cone-beam computed tomography projections of 2 skull phantoms were reconstructed using 6 reconstruction conditions and then compared using the Thurstone paired comparison method. Physical evaluations, including the modulation transfer function and the Wiener spectrum, as well as an assessment of space visibility, were undertaken using experimental phantoms. Image reconstruction using a modified Shepp-Logan filter resulted in better sensory, physical, and quantitative evaluations. The reconstruction conditions substantially improved the spatial resolution and visualization of the periodontal ligament space. The difference in sensitivity was obtained by altering the reconstruction filter. Modifying the characteristics of a reconstruction filter can generate significant improvement in assessments of the periodontal ligament space. A high-frequency enhancement filter improves the visualization of thin structures and will be useful when accurate assessment of the periodontal ligament space is necessary.
Optimizing brain tumor resection. High-field interventional MR imaging.
Tummala, R P; Chu, R M; Liu, H; Truwit, C L; Hall, W A
2001-11-01
High-field strength iMRI guidance is an effective tool for brain tumor resection. Although its use lengthens the average time for a craniotomy, the reward is a more extensive tumor excision compared with conventional neurosurgery without an increased risk to the patient (Table 4). Although intraoperative patient transfer into and out of the magnet is cumbersome, the possibility for complete resection, especially for a low-grade glioma, makes the effort worthwhile. The cost and technical support required for this system presently limits its use to only a few sites worldwide. As with any technology, further refinements will make this system less expensive and more attainable. Practical consideration aside, high-field strength iMRI is presently [table: see text] the most effective tool available for brain tumor resection. Because of its novelty, future studies are necessary to determine if this technology lowers the incidence of and extends the duration to tumor recurrence as the preliminary data in children suggests. These are the ultimate measures of efficacy for any brain tumor treatment. Based on the rapid advancement of technology, will today's high-field strength interventional magnet become tomorrow's low-field system? Very high-field strength designs may improve diagnostic capabilities through higher resolution, but their interventional applications may be hindered by increased sensitivity for clinically insignificant abnormalities and decreased specificity for clinically relevant lesions. As new technology is developed, clinicians must continue to explore and refine the existing high-field strength iMRI to make it cost-effective and widely applicable.
The Optimization of Electromagnetic Field in Microwave Structures
Directory of Open Access Journals (Sweden)
PALADE Paula Alexandra
2010-10-01
Full Text Available The paper presents a study ofelectromagnetic field in microwave structures. Thestudied applicator can be used for processing dielectricwith losses. The microwave oven is a metallic boxconnected to a 1 kW, 2.45 GHz microwave source via arectangular waveguide operating in the TE10 mode.Near the bottom of the oven there is a cylindrical glassplate with a rectangular dielectric placed on top of it.Processing technique in microwave field in contrast toRF processing is more complex and therefore the usedapplicators presents a more varied range.
Institute of Scientific and Technical Information of China (English)
冯尚明; 杨波
2009-01-01
A speed estimation method of linear induction motor(LIM) using a novel extended kalman filter(EKF) was presented in this paper. The modification for dynamic end effect of LIM was designed to achieve exact estimation results when LIM ran at high speed. A new approach of optimizing the performance of the extended kalman filter using simulated annealing genetic algorithm (SAGA) was compared with the use of a genetic algorithm(GA). The optimization techniques are verified effective by simulation on a field-oriented controller under various operating conditions including motor parame-ter sensitivity and load disturbance.%采用一种新颖的扩展卡尔曼滤波器(EKF)实现了对直线感应电动机的速度检测,并考虑边端效应的影响进行了修正.采用模拟退火遗传算法(SAGA)对EKF性能进行优化,并与遗传算法(GA)优化的EKF进行了比较,表明SAGA具有更强的寻优能力.包括电机参数变化、负载扰动等情况下的仿真结果证明了该方案的有效性.
Bauser, H. H.; Jaumann, S.; Roth, K.
2015-12-01
The Ensemble Kalman Filter (EnKF) is a widely used data assimilation method in soil hydrology to estimate states and parameters, incorporating uncertainties in measurements and all model components.Of these components not only states and parameters, but also the representation of small scale heterogeneities of different soil layers suffers from large uncertainties. This is particularly severe when measuring soil water content, which reflects the soil's local texture and is typically discontinuous across heterogeneity boundaries. To address this challenge we enhance the EnKF to simultaneously also estimate a Miller scaling field for each soil layer.The enhanced EnKF is tested with a one-dimensional water content data set based on time domain reflectometry (TDR) measurements and leads to an improved consistency of model and measurements.
A Two-Mode Mean-Field Optimal Switching Problem for the Full Balance Sheet
Directory of Open Access Journals (Sweden)
Boualem Djehiche
2014-01-01
a two-mode optimal switching problem of mean-field type, which can be described by a system of Snell envelopes where the obstacles are interconnected and nonlinear. The main result of the paper is a proof of a continuous minimal solution to the system of Snell envelopes, as well as the full characterization of the optimal switching strategy.
Energy Technology Data Exchange (ETDEWEB)
Dong Xufeng, E-mail: dongxf@dlut.edu.c [School of Materials Science and Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China); Ou Jinping [School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China); School of Civil Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150090 (China); Guan Xinchun [School of Civil Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150090 (China); Qi Min [School of Materials Science and Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China)
2010-11-15
Magnetostrictive properties have relationship with the applied orientation field during the preparation of giant magnetostrictive composites. To understand the dependence of the optimal orientation field on particle volume fraction, composites with 20%, 30% and 50% particles by volume were fabricated by distributing Terfenol-D particles in an unsaturated polyester resin under various orientation fields. Their magnetostrictive properties were tested without pre-stress at room temperature. The results indicate that as the particle volume fraction increases, the optimal orientation field increases. The main reason for this phenomenon is the packing density for the composites with higher particle volume fraction is larger than that for those with lower particle content.
Directory of Open Access Journals (Sweden)
Lin Zhang
2016-10-01
Full Text Available To measure the pushing distance of a hydraulic-powered roof support, and reduce the cost from a non-reusable displacement sensor embedded in pushing a hydraulic cylinder, an inertial sensor is used to measure the pushing distance, and a Kalman filter is applied to process the inertial data. To obtain better estimation performance, an improved fruit fly optimization algorithm (IFOA is proposed to tune the parameters of the Kalman filter, processing noise covariance Q and observation noise covariance R. The key procedures of the proposed method, including state-space model, fitness function, and Kalman filter implementation, are presented. Finally, an artificial signal is utilized to verify the feasibility of the proposed method, and the tuning results of other algorithms, particle swarm optimization (PSO, genetic algorithm (GA, basic FOA, and 3D-FOA are compared. The proposed method is also applied in the pushing distance estimation scenario. The simulation and application results prove the effectiveness and superiority of the proposed method.
Insect-Inspired Self-Motion Estimation with Dense Flow Fields--An Adaptive Matched Filter Approach.
Strübbe, Simon; Stürzl, Wolfgang; Egelhaaf, Martin
2015-01-01
The control of self-motion is a basic, but complex task for both technical and biological systems. Various algorithms have been proposed that allow the estimation of self-motion from the optic flow on the eyes. We show that two apparently very different approaches to solve this task, one technically and one biologically inspired, can be transformed into each other under certain conditions. One estimator of self-motion is based on a matched filter approach; it has been developed to describe the function of motion sensitive cells in the fly brain. The other estimator, the Koenderink and van Doorn (KvD) algorithm, was derived analytically with a technical background. If the distances to the objects in the environment can be assumed to be known, the two estimators are linear and equivalent, but are expressed in different mathematical forms. However, for most situations it is unrealistic to assume that the distances are known. Therefore, the depth structure of the environment needs to be determined in parallel to the self-motion parameters and leads to a non-linear problem. It is shown that the standard least mean square approach that is used by the KvD algorithm leads to a biased estimator. We derive a modification of this algorithm in order to remove the bias and demonstrate its improved performance by means of numerical simulations. For self-motion estimation it is beneficial to have a spherical visual field, similar to many flying insects. We show that in this case the representation of the depth structure of the environment derived from the optic flow can be simplified. Based on this result, we develop an adaptive matched filter approach for systems with a nearly spherical visual field. Then only eight parameters about the environment have to be memorized and updated during self-motion.
Insect-Inspired Self-Motion Estimation with Dense Flow Fields--An Adaptive Matched Filter Approach.
Directory of Open Access Journals (Sweden)
Simon Strübbe
Full Text Available The control of self-motion is a basic, but complex task for both technical and biological systems. Various algorithms have been proposed that allow the estimation of self-motion from the optic flow on the eyes. We show that two apparently very different approaches to solve this task, one technically and one biologically inspired, can be transformed into each other under certain conditions. One estimator of self-motion is based on a matched filter approach; it has been developed to describe the function of motion sensitive cells in the fly brain. The other estimator, the Koenderink and van Doorn (KvD algorithm, was derived analytically with a technical background. If the distances to the objects in the environment can be assumed to be known, the two estimators are linear and equivalent, but are expressed in different mathematical forms. However, for most situations it is unrealistic to assume that the distances are known. Therefore, the depth structure of the environment needs to be determined in parallel to the self-motion parameters and leads to a non-linear problem. It is shown that the standard least mean square approach that is used by the KvD algorithm leads to a biased estimator. We derive a modification of this algorithm in order to remove the bias and demonstrate its improved performance by means of numerical simulations. For self-motion estimation it is beneficial to have a spherical visual field, similar to many flying insects. We show that in this case the representation of the depth structure of the environment derived from the optic flow can be simplified. Based on this result, we develop an adaptive matched filter approach for systems with a nearly spherical visual field. Then only eight parameters about the environment have to be memorized and updated during self-motion.
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
Image-Based Particle Filtering For Robot Navigation In A Maize Field
Hiremath, S.; Evert, van F.K.; Heijden, van der G.W.A.M.; Braak, ter C.J.F.; Stein, A.
2012-01-01
Autonomous navigation of a robot in an agricultural field is a challenge as the robot is in an environment with many sources of noise. This includes noise due to uneven terrain, varying shapes, sizes and colors of the plants, imprecise sensor measurements and effects due to wheel-slippage. The drawb
Optimized 425MHz passive wireless magnetic field sensor
Li, Bodong
2014-06-01
A passive, magnetic field sensor consisting of a 425 MHz surface acoustic wave device loaded with a giant magnetoimpedance element is developed. The GMI element with a multilayer structure composed of Ni80Fe 20/Cu/Ni80Fe20, is fabricated on a 128° Y-X cut LiNbO3 LiNbO3 substrate. The integrated sensor is characterized with a network analyzer through an S-parameter measurement. Upon the application of a magnetic field, a maximum magnitude change and phase shift of 7.8 dB and 27 degree, respectively, are observed. Within the linear region, the magnetic sensitivity is 1.6 dB/Oe and 5 deg/Oe. © 2014 IEEE.
Altarawneh, M M
2012-09-01
We present a new technique to perform radio frequency (rf) contactless conductivity measurements in pulsed magnetic fields to probe different ground states in condensed matter physics. The new method utilizes a simple analog band-stop filter circuit implemented in a radio frequency transmission setup to perform contactless conductivity measurements. The new method is more sensitive than the other methods (e.g., the tunnel diode oscillator and the proximity detector oscillator) due to more sensitive dependence of the circuit resonance frequency on the tank circuit inductance (not the transmission line). More important, the new method is more robust than other methods when used to perform measurements in very high magnetic fields, works for a wide range of temperatures (i.e., 300 K-1.4 K) and is less sensitive to noise and mechanical vibrations during pulse magnet operation. The new technique was successfully applied to measure the Shubnikov-de Haas effect in Bi(2)Se(3) in pulsed magnetic fields of up to 60 T.
Concepts of magnetic filter fields in powerful negative ion sources for fusion
Energy Technology Data Exchange (ETDEWEB)
Kraus, W., E-mail: kraus@ipp.mpg.de; Fantz, U.; Heinemann, B.; Wünderlich, D. [Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany)
2016-02-15
The performance of large negative ion sources used in neutral beam injection systems is in long pulses mainly determined by the increase of the currents of co-extracted electrons. This is in particular a problem in deuterium and limits the ion currents which are for long pulses below the requirements for the ITER source. In the source of the ELISE test facility, the magnetic field in front of the first grid, which is essential to reduce the electron current, is generated by a current of several kA flowing through the plasma facing grid. Weakening of this field by the addition of permanent magnets placed close to the lateral walls has led to a reduction of the electron current by a factor three without loss of ion current when source was operated in volume production. If this effect can be validated for the cesiated source, it would be a large step towards achieving the ITER parameter in long pulses.
Optimal separation times for electrical field flow fractionation with Couette flows.
Pascal, Jennifer; O'Hara, Ryan; Oyanader, Mario; Arce, Pedro E
2008-11-01
The prediction of optimal times of separation as a function of the applied electrical field and cation valence have been studied for the case of field flow fractionation [Martin M., Giddings J. C., J. Phys. Chem. 1981, 85, 727] with charged solutes. These predictions can be very useful to a priori design or identify optimal operating conditions for a Couette-based device for field flow fractionation when the orthogonal field is an electrical field. Mathematically friendly relationships are obtained by applying the method of spatial averaging to the solute species continuity equation; this is accomplished after the role of the capillary geometrical dimensions on the applied electrical field equations has been assessed [Oyanader M. A., Arce P., Electrophoresis 2005; 26, 2857]. Moreover, explicit analytical expressions are derived for the effective parameters, i.e. diffusivity and convective velocity as functions of the applied (orthogonal) electrical field. These effective transport parameters are used to study the effect of the cation valence of the solutes and of the magnitude of the applied orthogonal electrical field on the values of the optimal time of separation. These parameters play a significant role in controlling the optimal separation time, leading to a family of minimum values, for particular magnitudes of the applied orthogonal electrical field.
Tunable extended depth of field using a liquid crystal annular spatial filter.
Klapp, Iftach; Solodar, Asi; Abdulhalim, Ibrahim
2014-03-15
A tunable extended depth of field (EDOF) imaging is presented using temporal multiplexing and a low-cost eight-ring, annular liquid crystal spatial light modulator. By changing between different phase profiles in the pupil plane of a lens we perform several levels of EDOF. Using these levels as a "database" it is shown by temporal multiplexing how to decompose tunable levels of EDOF.
Directory of Open Access Journals (Sweden)
Karl Friston
2010-01-01
Full Text Available We describe a Bayesian filtering scheme for nonlinear state-space models in continuous time. This scheme is called Generalised Filtering and furnishes posterior (conditional densities on hidden states and unknown parameters generating observed data. Crucially, the scheme operates online, assimilating data to optimize the conditional density on time-varying states and time-invariant parameters. In contrast to Kalman and Particle smoothing, Generalised Filtering does not require a backwards pass. In contrast to variational schemes, it does not assume conditional independence between the states and parameters. Generalised Filtering optimises the conditional density with respect to a free-energy bound on the model's log-evidence. This optimisation uses the generalised motion of hidden states and parameters, under the prior assumption that the motion of the parameters is small. We describe the scheme, present comparative evaluations with a fixed-form variational version, and conclude with an illustrative application to a nonlinear state-space model of brain imaging time-series.
An Optimization of Pulsed ElectroMagnetic Fields Study
Goodwin, Thomas J.
2006-01-01
To date, in our research we have focused on the use of normal human neuronal progenitor (NHNP) cells because of their importance in human nervous system regeneration, development and maintenance, but we have developed 2-D and 3-D bioreactors that can accommodate any cell line. In this Project, we will include the use of tissues important for physiological regeneration: Human osteoblasts or chondrocytes, and vascular cells. Our initial results with the NHNP cells were quite startling using extremely low-level electromagnetic fields (5 microtesla at 10Hz; 6mA). The low-amplitude, rapidly time-varying electromagnetic fields exert a very potent effect on the proliferation, morphology, and gene expression of the cells in culture, both in standard 2-dimensional culture plates as well as cells organized into 3-dimensional tissue-like assemblies (TLAs) in a 3D bioreactor. We have replicated our preliminary results many, many times, have analyzed the gene expression using gene arrays (followed by Luminex analysis for protein production), and have monitored cell proliferation, orientation, morphology, and glucose metabolism, and we are confident that we have a stable and reliable model to study the control of high-level cellular processes by application of low-amplitude, time varying electromagnetic fields (TVEMF) (1, 2). In additional studies at the University of Michigan, we have been able to generate functional in vitro engineered mammalian skeletal muscle, and have employed nerve-muscle co-culture techniques to promote axonal sprouting. We believe that nearly all tissues, in particular, neural, are susceptible to the influences of low-level TVEMF.
Kallman, Robert R.
1986-12-01
Phase-only (PO) and binary phase only (BPO) versions of recently developed Synthetic Discriminant Filters, SDFs, (Kallman, 1986) are discussed which are potentially useful for threshold optical correlation detectors. A formulation of the performance or SNR of a filter against a training set is first presented which takes into account the POF or BPOF, unlike the SDF, being unable to control the actual size of the recognition spike of the output correlation plane when a valid target is centered in the filter input plane. Numerical tests of the present recipes for POFs and BPOFs have been carried out on four SDFs made from tank imagery, and the SNR for 12 POFs and 24 BPOFs were computed.
Tools for Optimizing Management of a Spatially Variable Organic Field
Directory of Open Access Journals (Sweden)
Thomas Panagopoulos
2015-03-01
Full Text Available Geostatistical tools were used to estimate spatial relations between wheat yield and soil parameters under organic farming field conditions. Thematic maps of each factor were created as raster images in R software using kriging. The Geographic Resources Analysis Support System (GRASS calculated the principal component analysis raster images for soil parameters and yield. The correlation between the raster arising from the PC1 of soil and yield parameters showed high linear correlation (r = 0.75 and explained 48.50% of the data variance. The data show that durum wheat yield is strongly affected by soil parameter variability, and thus, the average production can be substantially lower than its potential. Soil water content was the limiting factor to grain yield and not nitrate as in other similar studies. The use of precision agriculture tools helped reduce the level of complexity between the measured parameters by the grouping of several parameters and demonstrating that precision agriculture tools can be applied in small organic fields, reducing costs and increasing wheat yield. Consequently, site-specific applications could be expected to improve the yield without increasing excessively the cost for farmers and enhance environmental and economic benefits.
1987-12-01
FIR filter can be described in the following. [Ref. 2] 1. FIR filters with exact linear phase can be easily designed. Linear phase filters are important...response for the four cases of linear phase filter , i.e., even or odd symmetry with an even or odd number of terms, can be written in the form: H (eJ ) = e...Ansari, The Design and Application of Optimal FIR Fractional Phase Filters , IEEE on Acoutics, Speech and Signal Processing, Vol. 2, 1987, pp.896-899. 77 14
Simultaneous optimization of micro-heliostat geometry and field layout using a genetic algorithm
Lazardjani, Mani Yousefpour; Kronhardt, Valentina; Dikta, Gerhard; Göttsche, Joachim
2016-05-01
A new optimization tool for micro-heliostat (MH) geometry and field layout is presented. The method intends simultaneous performance improvement and cost reduction through iteration of heliostat geometry and field layout parameters. This tool was developed primarily for the optimization of a novel micro-heliostat concept, which was developed at Solar-Institut Jülich (SIJ). However, the underlying approach for the optimization can be used for any heliostat type. During the optimization the performance is calculated using the ray-tracing tool SolCal. The costs of the heliostats are calculated by use of a detailed cost function. A genetic algorithm is used to change heliostat geometry and field layout in an iterative process. Starting from an initial setup, the optimization tool generates several configurations of heliostat geometries and field layouts. For each configuration a cost-performance ratio is calculated. Based on that, the best geometry and field layout can be selected in each optimization step. In order to find the best configuration, this step is repeated until no significant improvement in the results is observed.
Adapting crop management practices to climate change: Modeling optimal solutions at the field scale
Lehmann, N.; Finger, R.; Klein, T.; Calanca, P.; Walter, A.
2013-01-01
Climate change will alter the environmental conditions for crop growth and require adjustments in management practices at the field scale. In this paper, we analyzed the impacts of two different climate change scenarios on optimal field management practices in winterwheat and grain maize production
ADVANCED HOT GAS FILTER DEVELOPMENT
Energy Technology Data Exchange (ETDEWEB)
E.S. Connolly; G.D. Forsythe
2000-09-30
DuPont Lanxide Composites, Inc. undertook a sixty-month program, under DOE Contract DEAC21-94MC31214, in order to develop hot gas candle filters from a patented material technology know as PRD-66. The goal of this program was to extend the development of this material as a filter element and fully assess the capability of this technology to meet the needs of Pressurized Fluidized Bed Combustion (PFBC) and Integrated Gasification Combined Cycle (IGCC) power generation systems at commercial scale. The principal objective of Task 3 was to build on the initial PRD-66 filter development, optimize its structure, and evaluate basic material properties relevant to the hot gas filter application. Initially, this consisted of an evaluation of an advanced filament-wound core structure that had been designed to produce an effective bulk filter underneath the barrier filter formed by the outer membrane. The basic material properties to be evaluated (as established by the DOE/METC materials working group) would include mechanical, thermal, and fracture toughness parameters for both new and used material, for the purpose of building a material database consistent with what is being done for the alternative candle filter systems. Task 3 was later expanded to include analysis of PRD-66 candle filters, which had been exposed to actual PFBC conditions, development of an improved membrane, and installation of equipment necessary for the processing of a modified composition. Task 4 would address essential technical issues involving the scale-up of PRD-66 candle filter manufacturing from prototype production to commercial scale manufacturing. The focus would be on capacity (as it affects the ability to deliver commercial order quantities), process specification (as it affects yields, quality, and costs), and manufacturing systems (e.g. QA/QC, materials handling, parts flow, and cost data acquisition). Any filters fabricated during this task would be used for product qualification tests
Condition Monitoring of Rolling Element Bearings Using Optimal Gabor Filters%采用Gabor滤波器的轴承状态监控方法
Institute of Scientific and Technical Information of China (English)
张丹; 隋文涛; 郭前建
2016-01-01
针对滚动轴承状态监控中最优共振频带难确定的问题，提出一种新的寻优方法和目标函数，可快速准确地定位共振频带，提取状态信息。通过两步网格搜索法，以包络稀疏性为目标函数，对Gabor滤波器参数寻优；然后对振动信号进行滤波并得到信号包络；最后运用包络自相关谱抑制噪声，突出运行状态信息。用仿真信号和实际信号对该方法进行了验证，结果表明，该方法能准确判明轴承运行状态。%Aiming to the difficulty in finding the resonant frequency band in condition monitoring of roll-ing element bearings, a new optimization method and objective function was proposed. The resonant fre-quency band can be located through this proposed method. Firstly, the parameters of Gabor filter are op-timized through the two-step grid search method, in which the envelope sparseness is as objective func-tion. The vibration signal was filtered through the optimal filter and the envelop signal was calculated. The envelop autocorrelation spectrum was adopted to restrain noise and highlight operation condition infor-mation. The effectiveness and advantages of the proposed method were proved through the simulation sig-nal and experimental signals. It is shown that the bearing operation condition can be recognized accurate-ly by the proposed method.
Directory of Open Access Journals (Sweden)
Chodun Rafal
2016-03-01
Full Text Available This work presents the very first results of the application of plasma magnetic filtering achieved by a coil coupled with an electrical circuit of a coaxial accelerator during the synthesis of A1N thin films by use of Impulse Plasma Deposition method (IPD. The uniqueness of this technical solution lies in the fact that the filter is not supplied, controlled and synchronized from any external device. Our solution uses the energy from the electrical circuit of plasma accelerator. The plasma state was described on the basis of OES studies. Estimation of the effects of plasma filtering on the film quality was carried out on the basis of characterization of structure morphology (SEM, phase and chemical composition (vibrational spectroscopy. Our work has shown that the use of the developed magnetic self-filter improved the structure of the AlN coatings synthesized under the condition of impulse plasma, especially by the minimization of the tendency to deposit metallic aluminum droplets and columnar growth.
Energy Technology Data Exchange (ETDEWEB)
Das, B. K., E-mail: bdyt.ds@rediffmail.com; Hazarika, P.; Chakraborty, M. [Centre of Plasma Physics-Institute for Plasma Research, Tepesia-782402, Kamrup, Assam (India); Bandyopadhyay, M., E-mail: mainak@iter-india.org [ITER-India, Institute for Plasma Research, Gandhinagar-382025, Gujarat (India)
2014-07-15
A study on the transport of charged particles across a magnetic filter field has been carried out in a double plasma device (DPD) and presented in this manuscript. The DPD is virtually divided into two parts viz. source and target regions by a transverse magnetic field (TMF) which is constructed by inserting strontium ferrite magnets into two stainless steel rectangular tubes. Plasma electrons are magnetized but ions are unmagnetized inside the TMF region. Negative voltages are applied to the TMF tubes in order to reduce the loss of electrons towards them. Plasma is produced in the source region by filament discharge method and allowed to flow towards the target region through this negatively biased TMF. It is observed that in the target region, plasma density can be increased and electron temperature decreased with the help of negatively biased TMF. This observation is beneficial for negative ion source development. Plasma diffusion across the negatively biased TMF follows Bohm or anomalous diffusion process when negative bias voltage is very less. At higher negative bias, diffusion coefficient starts deviating from the Bohm diffusion value, associated with enhanced plasma flow in the target region.
A Markov-random-field-based filter for speckle reduction in ultrasound imagery
Lankoande, Ousseini; Hayat, Majeed M.; Santhanam, Balu
2009-02-01
The coherent nature of ultrasound imaging inherently produces the notorious signal-dependent speckle noise. Recently, a novel approach based upon embedding the statistical and physical properties of speckle patterns into a Markov-random-field (MRF) framework was developed and demonstrated by the authors in the context of synthetic-aperture radar imaging. The contributions of this work are twofold. First, the MRF approach is extended to include a pseudo maximum-likelihood estimator of a key model parameter, making the approach fully autonomous. Second, the capability of the extended approach, called the modified MRF-based conditional-expectation approach (MRFCEA), in denoising real ultrasound imagery is demonstrated. The proposed MRFCEA approach offers superior performance over existing methods by reducing speckle noise without compromising the spatial resolution. In addition, MRFCEA is autonomous, contrary to existing methods such as the enhanced-Frost or the modified-Lee, which require user's input.
Mukherjee, P; Hazra, L N
2014-02-01
Pupil plane filtering by radial Walsh filters is a convenient technique for tailoring the axial intensity distribution near the focal plane of a rotationally symmetric imaging system. Radial Walsh filters, derived from radial Walsh functions, form a set of orthogonal phase filters that take on values either 0 or π phase, corresponding to +1 or -1 values of the radial Walsh functions over prespecified annular regions of the circular filter. Order of these filters is given by the number of zero-crossings, or equivalently phase transitions within the domain over which the set is defined. In general, radial Walsh filters are binary phase zone plates, each of them demonstrating distinct focusing characteristics. The set of radial Walsh filters can be classified into distinct groups, where the members of each group possess self-similar structures. Self-similarity can also be observed in the corresponding axial intensity distributions. These observations provide valuable clues in tackling the inverse problem of synthesis of phase filter in accordance with prespecified axial intensity distributions. This paper reports our observations on self-similarity in radial Walsh filters of various orders and corresponding axial intensity distributions.
Optimized molten salt receivers for ultimate trough solar fields
Riffelmann, Klaus-J.; Richert, Timo; Kuckelkorn, Thomas
2016-05-01
Today parabolic trough collectors are the most successful concentrating solar power (CSP) technology. For the next development step new systems with increased operation temperature and new heat transfer fluids (HTF) are currently developed. Although the first power tower projects have successfully been realized, up to now there is no evidence of an all-dominant economic or technical advantage of power tower or parabolic trough. The development of parabolic trough technology towards higher performance and significant cost reduction have led to significant improvements in competitiveness. The use of molten salt instead of synthetic oil as heat transfer fluid will bring down the levelized costs of electricity (LCOE) even further while providing dispatchable energy with high capacity factors. FLABEG has developed the Ultimate TroughTM (UT) collector, jointly with sbp Sonne GmbH and supported by public funds. Due to its validated high optical accuracy, the collector is very suitable to operate efficiently at elevated temperatures up to 550 °C. SCHOTT will drive the key-innovations by introducing the 4th generation solar receiver that addresses the most significant performance and cost improvement measures. The new receivers have been completely redesigned to provide a product platform that is ready for high temperature operation up to 550 °C. Moreover distinct product features have been introduced to reduce costs and risks in solar field assembly and installation. The increased material and design challenges incurred with the high temperature operation have been reflected in sophisticated qualification and validation procedures.
Wang, Xiaochun; Yu, Tse Kuan; Salehpour, Mohammad; Zhang, Sean X; Sun, Tzouh Liang; Buchholz, Thomas A
2009-05-01
To assess whether using an anterior oblique supraclavicular (SCV) field with a posterior axillary boost (PAB) field is an optimal technique for targeting axillary (AX) lymph nodes compared with two computed tomography (CT)-based techniques: (1) an SCV field with an anterior boost field and (2) intensity-modulated radiotherapy (IMRT). Ten patients with CT simulation data treated with postmastectomy radiation that included an SCV field were selected for the study. Supraclavicular nodes and AX Level I-III nodes within the SCV field were contoured and defined as the treatment target. Plans using the three techniques were generated and evaluated for each patient. The anterior axillary boost field and IMRT resulted in superior dose coverage compared with PAB. Namely, treatment volumes that received 105%, 80%, and 30% of prescribed dose for IMRT plans were significantly less than those for the anterior axillary boost plans, which were significantly less than PAB. For PAB and anterior axillary boost plans, there was a linear correlation between treatment volume receiving 105% of prescribed dose and maximum target depth. Furthermore, the IMRT technique resulted in better lung sparing and dose conformity to the target than anterior axillary boost, which again was significantly better than PAB. The maximum cord dose for IMRT was small, but higher than for the other two techniques. More monitor units were required to deliver the IMRT plan than the PAB plan, which was more than the anterior axillary boost plan. The PAB technique is not optimal for treatment of AX lymph nodes in an SCV field. We conclude that CT treatment planning with dose optimization around delineated target volumes should become standard for radiation treatments of supraclavicular and AX lymph nodes.
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.
Energy Technology Data Exchange (ETDEWEB)
Stebbings, S L; Suessmann, F; Yang, Y-Y; Kling, M F [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strass e 1, 85748 Garching (Germany); Scrinzi, A [Ludwig-Maximilians-Universitaet Muenchen, Theresienstrasse 37, 80333 Muenchen (Germany); Durach, M; Rusina, A; Stockman, M I, E-mail: sarah.stebbings@mpq.mpg.de, E-mail: mstockman@gsu.edu, E-mail: matthias.kling@mpq.mpg.de [Department of Physics and Astronomy, Georgia State University, 29 Peachtree Center Avenue, Atlanta, GA 30303 (United States)
2011-07-15
The production of extreme ultraviolet (XUV) radiation via nanoplasmonic field-enhanced high-harmonic generation (HHG) in gold nanostructures at MHz repetition rates is investigated theoretically in this paper. Analytical and numerical calculations are employed and compared in order to determine the plasmonic fields in gold ellipsoidal nanoparticles. The comparison indicates that numerical calculations can accurately predict the field enhancement and plasmonic decay, but may encounter difficulties when attempting to predict the oscillatory behavior of the plasmonic field. Numerical calculations for coupled symmetric and asymmetric ellipsoids for different carrier-envelope phases (CEPs) of the driving laser field are combined with time-dependent Schroedinger equation simulations to predict the resulting HHG spectra. The studies reveal that the plasmonic field oscillations, which are controlled by the CEP of the driving laser field, play a more important role than the nanostructure configuration in finding the optimal conditions for the generation of isolated attosecond XUV pulses via nanoplasmonic field enhancement.
Stebbings, S. L.; Süßmann, F.; Yang, Y.-Y.; Scrinzi, A.; Durach, M.; Rusina, A.; Stockman, M. I.; Kling, M. F.
2011-07-01
The production of extreme ultraviolet (XUV) radiation via nanoplasmonic field-enhanced high-harmonic generation (HHG) in gold nanostructures at MHz repetition rates is investigated theoretically in this paper. Analytical and numerical calculations are employed and compared in order to determine the plasmonic fields in gold ellipsoidal nanoparticles. The comparison indicates that numerical calculations can accurately predict the field enhancement and plasmonic decay, but may encounter difficulties when attempting to predict the oscillatory behavior of the plasmonic field. Numerical calculations for coupled symmetric and asymmetric ellipsoids for different carrier-envelope phases (CEPs) of the driving laser field are combined with time-dependent Schrödinger equation simulations to predict the resulting HHG spectra. The studies reveal that the plasmonic field oscillations, which are controlled by the CEP of the driving laser field, play a more important role than the nanostructure configuration in finding the optimal conditions for the generation of isolated attosecond XUV pulses via nanoplasmonic field enhancement.
Kumar, M.; Mishra, S K; S S Sahu
2016-01-01
Gaussian noise is one of the dominant noises, which degrades the quality of acquired Computed Tomography (CT) image data. It creates difficulties in pathological identification or diagnosis of any disease. Gaussian noise elimination is desirable to improve the clarity of a CT image for clinical, diagnostic, and postprocessing applications. This paper proposes an evolutionary nonlinear adaptive filter approach, using Cat Swarm Functional Link Artificial Neural Network (CS-FLANN) to remove the ...
Bonnet, V; Dumas, R; Cappozzo, A; Joukov, V; Daune, G; Kulić, D; Fraisse, P; Andary, S; Venture, G
2016-12-29
This paper presents a method for real-time estimation of the kinematics and kinetics of a human body performing a sagittal symmetric motor task, which would minimize the impact of the stereophotogrammetric soft tissue artefacts (STA). The method is based on a bi-dimensional mechanical model of the locomotor apparatus the state variables of which (joint angles, velocities and accelerations, and the segments lengths and inertial parameters) are estimated by a constrained extended Kalman filter (CEKF) that fuses input information made of both stereophotogrammetric and dynamometric measurement data. Filter gains are made to saturate in order to obtain plausible state variables and the measurement covariance matrix of the filter accounts for the expected STA maximal amplitudes. We hypothesised that the ensemble of constraints and input redundant information would allow the method to attenuate the STA propagation to the end results. The method was evaluated in ten human subjects performing a squat exercise. The CEKF estimated and measured skin marker trajectories exhibited a RMS difference lower than 4mm, thus in the range of STAs. The RMS differences between the measured ground reaction force and moment and those estimated using the proposed method (9N and 10Nm) were much lower than obtained using a classical inverse dynamics approach (22N and 30Nm). From the latter results it may be inferred that the presented method allows for a significant improvement of the accuracy with which kinematic variables and relevant time derivatives, model parameters and, therefore, intersegmental moments are estimated.
Directory of Open Access Journals (Sweden)
J. Díaz-Carmona
2005-01-01
Full Text Available En este artículo se describe el diseño en el dominio de la frecuencia de filtros digitales FIR de retraso fraccionario (Fractional Delay Filter, FDF con características de ancho de banda amplio y una resolución fina de retraso. El método de diseño en frecuencia utilizado está basado en optimización con mínimos cuadrados en la aproximación de series de Taylor de la señal de entrada. La propuesta consiste en reducir la complejidad de la optimización en frecuencia al momento de diseñar el FDF. Lo anterior se logra con la combinación de una estructura multirazón (multirate y una estructura Farrow modificada. El filtro resultante presenta como ventajas un número reducido de operaciones por muestra de salida y una reducción notable en la carga computacional de diseño.A frequency domain design method for fractional delay FIR filters (Fractional Delay Filter, FDF with wide bandwidth and fine delay resolution is described. The frequency domain method is based on a least square Taylor series approximation of the input signal. The proposed design method consists of reducing the complexity of the frequency optimization workload in the design of the FDF. This is obtained by the combination of a multirate structure and a modified Farrow structure. The resulting filter has a reduced number of arithmetic operations per output sample and yields a significant reduction in the design computational workload.
Multi-objective optimization of the management of a waterworks using an integrated well field model
DEFF Research Database (Denmark)
Hansen, Annette Kirstine; Bauer-Gottwein, Peter; Rosbjerg, Dan
2012-01-01
This study uses multi-objective optimization of an integrated well field model to improve the management of a waterworks. The well field model, called WELLNES (WELL field Numerical Engine Shell) is a dynamic coupling of a groundwater model, a pipe network model, and a well model. WELLNES is capable...... of predicting the water level and the energy consumption of the individual production wells. The model has been applied to Søndersø waterworks in Denmark, where it predicts the energy consumption within 1.8% of the observed. The objectives of the optimization problem are to minimize the specific energy...... provides the decision-makers with compromise solutions between the two competing objectives. In the test case the Pareto optimal solutions are compared with an exhaustive benchmark solution. It is shown that the energy consumption can be reduced by 4% by changing the pumping configuration without violating...