Improved selection in totally monotone arrays
Energy Technology Data Exchange (ETDEWEB)
Mansour, Y. (Harvard Univ., Cambridge, MA (United States). Aiken Computation Lab.); Park, J.K. (Sandia National Labs., Albuquerque, NM (United States)); Schieber, B. (International Business Machines Corp., Yorktown Heights, NY (United States). Thomas J. Watson Research Center); Sen, S. (AT and T Bell Labs., Murray Hill, NJ (United States))
1991-01-01
This paper's main result is an O(({radical}{bar m}lgm)(n lg n) + mlg n)-time algorithm for computing the kth smallest entry in each row of an m {times} n totally monotone array. (A two-dimensional A = a(i,j) is totally monotone if for all i{sub 1} < i{sub 2} and j{sub 1} < j{sup 2}, < a(i{sub 1},j{sub 2}) implies a(i{sub 2},j{sub 1})). For large values of k (in particular, for k=(n/2)), this algorithm is significantly faster than the O(k(m+n))-time algorithm for the same problem due to Kravets and Park. An immediate consequence of this result is an O(n{sup 3/2} lg{sup 2}n)-time algorithm for computing the kth nearest neighbor of each vertex of a convex n-gon. In addition to the main result, we also give an O(n lg m)-time algorithm for computing an approximate median in each row of an m {times} n totally monotone array; this approximate median is an entry whose rank in its row lies between (n/4) and (3n/4) {minus} 1. 20 refs., 3 figs.
Stelman, David
1989-01-01
A contactor/filter arrangement for removing particulate contaminants from a gaseous stream includes a housing having a substantially vertically oriented granular material retention member with upstream and downstream faces, a substantially vertically oriented microporous gas filter element, wherein the retention member and the filter element are spaced apart to provide a zone for the passage of granular material therethrough. The housing further includes a gas inlet means, a gas outlet means, and means for moving a body of granular material through the zone. A gaseous stream containing particulate contaminants passes through the gas inlet means as well as through the upstream face of the granular material retention member, passing through the retention member, the body of granular material, the microporous gas filter element, exiting out of the gas outlet means. Disposed on the upstream face of the filter element is a cover screen which isolates the filter element from contact with the moving granular bed and collects a portion of the particulates so as to form a dust cake having openings small enough to exclude the granular material, yet large enough to receive the dust particles. In one embodiment, the granular material is comprised of prous alumina impregnated with CuO, with the cover screen cleaned by the action of the moving granular material as well as by backflow pressure pulses.
An improved proximal-based decomposition method for structured monotone variational inequalities
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The proximal-based decomposition method was originally proposed by Chen and Teboulle (Math. Programming, 1994, 64:81-101 for solving convex minimization problems. This paper extends it to solving monotone variational inequalities associated with separable structures with the improvements that the restrictive assumptions on the involved parameters are much relaxed, and thus makes it practical to solve the subproblems easily. Without additional assumptions, global convergence of the new method is proved under the same mild assumptions on the problem's data as the original method.
Improved directional-distance filter
Institute of Scientific and Technical Information of China (English)
2008-01-01
This paper proposes a new spatial-distance weighting function.By combining the weighting function and the traditional directional-distance filter (DDF) in a novel way,a new vector filter-the adaptive distance-weighted directional-distance filter (ADWDDF)-is presented.The experimental results show that the proposed solution provides better filtering performance and preserves better image chromaticity and edge or detail information compared with the traditional DDF and some other typical vector filters.
Image Filtering Based on Improved Information Entropy
Institute of Scientific and Technical Information of China (English)
JINGXiaojun; LIUYulin; XIONGYuqing
2004-01-01
An image filtering based on improved information entropy is proposed in this paper, which can overcome the shortcomings of hybrid linear and non-linear filtering algorithm. Due to the shortcomings of information entropy in the field of data fusion, we introduce the consistency constraint factor of sub-source report and subsource performance difference parameter, propose the concept of fusion entropy, utilize its amendment and regularity function on sub-source decision-making matrix, bring into play the competency, redundency and complementarity of information fusion, suppress and delete fault and invalid information, strengthen and preserve correct and useful information, overcome the risk of error reporting on single source critical point and the shortcomings of reliability and error tolerating, add the decision-making criteria of multiple sub-source fusion, finally improve filtering quality. Subsequent experiments show its validity and improved filtering performance, thus providing a new way of image filtering technique.
IMPROVED MLV FILTER TO REMOVE MULTIPLICATIVE NOISE
Institute of Scientific and Technical Information of China (English)
Li Weibin; Liu Fang; Jiao Licheng; Zhang Shuling; Li Zongling
2006-01-01
More methods can be used to remove the additive noise, such as the Mean of Least Variance (MLV)filter. When the signal is noised by the multiplicative noise, it is difficult to remove. The paper presents an improved filter to remove multiplicative noise by changing the multiplicative noise to the additive noise, and then using the MLV-like to remove the additive noise. The simulation results show that the performance is better than Minimum Coefficient of Variation (MCV) filter and MLV filter. Both one-dimension and image experiments demonstrate its theoretical performance.
Englander, Jacob A.; Englander, Arnold C.
2014-01-01
Trajectory optimization methods using monotonic basin hopping (MBH) have become well developed during the past decade [1, 2, 3, 4, 5, 6]. An essential component of MBH is a controlled random search through the multi-dimensional space of possible solutions. Historically, the randomness has been generated by drawing random variable (RV)s from a uniform probability distribution. Here, we investigate the generating the randomness by drawing the RVs from Cauchy and Pareto distributions, chosen because of their characteristic long tails. We demonstrate that using Cauchy distributions (as first suggested by J. Englander [3, 6]) significantly improves monotonic basin hopping (MBH) performance, and that Pareto distributions provide even greater improvements. Improved performance is defined in terms of efficiency and robustness. Efficiency is finding better solutions in less time. Robustness is efficiency that is undiminished by (a) the boundary conditions and internal constraints of the optimization problem being solved, and (b) by variations in the parameters of the probability distribution. Robustness is important for achieving performance improvements that are not problem specific. In this work we show that the performance improvements are the result of how these long-tailed distributions enable MBH to search the solution space faster and more thoroughly. In developing this explanation, we use the concepts of sub-diffusive, normally-diffusive, and super-diffusive random walks (RWs) originally developed in the field of statistical physics.
MONOTONIZATION IN GLOBAL OPTIMIZATION
Institute of Scientific and Technical Information of China (English)
WU ZHIYOU; BAI FUSHENG; ZHANG LIANSHENG
2005-01-01
A general monotonization method is proposed for converting a constrained programming problem with non-monotone objective function and monotone constraint functions into a monotone programming problem. An equivalent monotone programming problem with only inequality constraints is obtained via this monotonization method. Then the existingconvexification and concavefication methods can be used to convert the monotone programming problem into an equivalent better-structured optimization problem.
Improved image filter based on SPCNN
Institute of Scientific and Technical Information of China (English)
ZHANG YuDong; WU LeNan
2008-01-01
By extraction of the thoughts of non-linear model and adaptive model match, an improved Nagao filter is brought. Meanwhile a technique based on simplified pulse coupled neural network and used for noise positioning, is put forward. Combining the two methods above, we acquire a new method that can restore images corrupted by salt and pepper noise. Experiments show that this method is more preferable than other popular ones, and still works well while noise density fluctuates severely.
Improving information filtering via network manipulation
Zhang, Fuguo
2012-01-01
Recommender system is a very promising way to address the problem of overabundant information for online users. Though the information filtering for the online commercial systems received much attention recently, almost all of the previous works are dedicated to design new algorithms and consider the user-item bipartite networks as given and constant information. However, many problems for recommender systems such as the cold-start problem (i.e. low recommendation accuracy for the small degree items) are actually due to the limitation of the underlying user-item bipartite networks. In this letter, we propose a strategy to enhance the performance of the already existing recommendation algorithms by directly manipulating the user-item bipartite networks, namely adding some virtual connections to the networks. Numerical analyses on two benchmark data sets, MovieLens and Netflix, show that our method can remarkably improve the recommendation performance. Specifically, it not only improve the recommendations accur...
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...
Monotone Boolean approximation
Energy Technology Data Exchange (ETDEWEB)
Hulme, B.L.
1982-12-01
This report presents a theory of approximation of arbitrary Boolean functions by simpler, monotone functions. Monotone increasing functions can be expressed without the use of complements. Nonconstant monotone increasing functions are important in their own right since they model a special class of systems known as coherent systems. It is shown here that when Boolean expressions for noncoherent systems become too large to treat exactly, then monotone approximations are easily defined. The algorithms proposed here not only provide simpler formulas but also produce best possible upper and lower monotone bounds for any Boolean function. This theory has practical application for the analysis of noncoherent fault trees and event tree sequences.
Improving information filtering via network manipulation
Zhang, Fuguo; Zeng, An
2012-12-01
The recommender system is a very promising way to address the problem of overabundant information for online users. Although the information filtering for the online commercial systems has received much attention recently, almost all of the previous works are dedicated to design new algorithms and consider the user-item bipartite networks as given and constant information. However, many problems for recommender systems such as the cold-start problem (i.e., low recommendation accuracy for the small-degree items) are actually due to the limitation of the underlying user-item bipartite networks. In this letter, we propose a strategy to enhance the performance of the already existing recommendation algorithms by directly manipulating the user-item bipartite networks, namely adding some virtual connections to the networks. Numerical analyses on two benchmark data sets, MovieLens and Netflix, show that our method can remarkably improves the recommendation performance. Specifically, it not only improves the recommendations accuracy (especially for the small-degree items), but also helps the recommender systems generate more diverse and novel recommendations.
Directory of Open Access Journals (Sweden)
R. Bharadwaj
2008-06-01
Full Text Available Coalescing filters are widely used throughout industry and improved performance will reduce droplet emissions and operating costs. Experimental observations show orientation of micro fibers in filter media effect the permeability and the separation efficiency of the filter media. In this work two methods are used to align the fibers to alter the filter structure. The results show that axially aligned fiber media improve quality factor on the order of 20% and cutting media on an angle from a thick layered media can improve performance by about 40%. The results also show the improved performance is not monotonically correlated to the average fiber angle of the medium.
Energy Technology Data Exchange (ETDEWEB)
Korshunov, A D [S.L. Sobolev Institute for Mathematics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)
2003-10-31
Monotone Boolean functions are an important object in discrete mathematics and mathematical cybernetics. Topics related to these functions have been actively studied for several decades. Many results have been obtained, and many papers published. However, until now there has been no sufficiently complete monograph or survey of results of investigations concerning monotone Boolean functions. The object of this survey is to present the main results on monotone Boolean functions obtained during the last 50 years.
Compensation mechanisms that improve distractor filtering are short-lived.
Allon, Ayala S; Luria, Roy
2017-07-01
We investigated possible compensation mechanisms for improving filtering of distractors from entering visual Working Memory (WM). Participants preformed a change-detection task in which three targets, six targets, or three targets along with three distractors (the filtering trial) were randomly presented. In six experiments, we tried to reduce the filtering cost, calculated as the difference in accuracy between the three targets and the filtering condition, by either cueing the possible locations of the distractors using placeholders (that could be either fixed throughout the experiment or change every trial; i.e., location cue), or by providing the location cue coupled with a warning cue singling the upcoming filtering trial. Results revealed that the filtering cost was not reduced by a fixed location cue (Experiment 1 and Experiment 5). However, the fixed location cue coupled with a warning cue (Experiment 2 and Experiment 5) or a location cue that changed positions every trial (Experiment 6), were sufficient to reduce the filtering cost. Additionally, longer preparation interval for filtering trials did not further reduce the filtering cost (Experiment 3). We argue these findings support that in the context of visual WM, spatial filtering settings can only be held for a limited amount of time. Thus, these filtering settings must be reactivated in order to be effective and to reduce the filtering cost. Copyright © 2017 Elsevier B.V. All rights reserved.
Distributed SLAM using improved particle filter for mobile robot localization.
Pei, Fujun; Wu, Mei; Zhang, Simin
2014-01-01
The distributed SLAM system has a similar estimation performance and requires only one-fifth of the computation time compared with centralized particle filter. However, particle impoverishment is inevitably because of the random particles prediction and resampling applied in generic particle filter, especially in SLAM problem that involves a large number of dimensions. In this paper, particle filter use in distributed SLAM was improved in two aspects. First, we improved the important function of the local filters in particle filter. The adaptive values were used to replace a set of constants in the computational process of importance function, which improved the robustness of the particle filter. Second, an information fusion method was proposed by mixing the innovation method and the number of effective particles method, which combined the advantages of these two methods. And this paper extends the previously known convergence results for particle filter to prove that improved particle filter converges to the optimal filter in mean square as the number of particles goes to infinity. The experiment results show that the proposed algorithm improved the virtue of the DPF-SLAM system in isolate faults and enabled the system to have a better tolerance and robustness.
Distributed SLAM Using Improved Particle Filter for Mobile Robot Localization
Directory of Open Access Journals (Sweden)
Fujun Pei
2014-01-01
Full Text Available The distributed SLAM system has a similar estimation performance and requires only one-fifth of the computation time compared with centralized particle filter. However, particle impoverishment is inevitably because of the random particles prediction and resampling applied in generic particle filter, especially in SLAM problem that involves a large number of dimensions. In this paper, particle filter use in distributed SLAM was improved in two aspects. First, we improved the important function of the local filters in particle filter. The adaptive values were used to replace a set of constants in the computational process of importance function, which improved the robustness of the particle filter. Second, an information fusion method was proposed by mixing the innovation method and the number of effective particles method, which combined the advantages of these two methods. And this paper extends the previously known convergence results for particle filter to prove that improved particle filter converges to the optimal filter in mean square as the number of particles goes to infinity. The experiment results show that the proposed algorithm improved the virtue of the DPF-SLAM system in isolate faults and enabled the system to have a better tolerance and robustness.
Adaptive Filtering Queueing for Improving Fairness
Directory of Open Access Journals (Sweden)
Jui-Pin Yang
2015-06-01
Full Text Available In this paper, we propose a scalable and efficient Active Queue Management (AQM scheme to provide fair bandwidth sharing when traffic is congested dubbed Adaptive Filtering Queueing (AFQ. First, AFQ identifies the filtering level of an arriving packet by comparing it with a flow label selected at random from the first level to an estimated level in the filtering level table. Based on the accepted traffic estimation and the previous fair filtering level, AFQ updates the fair filtering level. Next, AFQ uses a simple packet-dropping algorithm to determine whether arriving packets are accepted or discarded. To enhance AFQ’s feasibility in high-speed networks, we propose a two-layer mapping mechanism to effectively simplify the packet comparison operations. Simulation results demonstrate that AFQ achieves optimal fairness when compared with Rotating Preference Queues (RPQ, Core-Stateless Fair Queueing (CSFQ, CHOose and Keep for responsive flows, CHOose and Kill for unresponsive flows (CHOKe and First-In First-Out (FIFO schemes under a variety of traffic conditions.
Improved Kalman Filter-Based Speech Enhancement with Perceptual Post-Filtering
Institute of Scientific and Technical Information of China (English)
WEIJianqiang; DULimin; YANZhaoli; ZENGHui
2004-01-01
In this paper, a Kalman filter-based speech enhancement algorithm with some improvements of previous work is presented. A new technique based on spectral subtraction is used for separation speech and noise characteristics from noisy speech and for the computation of speech and noise Autoregressive (AR) parameters. In order to obtain a Kalman filter output with high audible quality, a perceptual post-filter is placed at the output of the Kalman filter to smooth the enhanced speech spectra.Extensive experiments indicate that this newly proposed method works well.
Improving Software Quality Prediction by Noise Filtering Techniques
Institute of Scientific and Technical Information of China (English)
Taghi M. Khoshgoftaar; Pierre Rebours
2007-01-01
Accuracy of machine learners is affected by quality of the data the learners are induced on. In this paper,quality of the training dataset is improved by removing instances detected as noisy by the Partitioning Filter. The fit datasetis first split into subsets, and different base learners are induced on each of these splits. The predictions are combined insuch a way that an instance is identified as noisy if it is misclassified by a certain number of base learners. Two versionsof the Partitioning Filter are used: Multiple-Partitioning Filter and Iterative-Partitioning Filter. The number of instancesremoved by the filters is tuned by the voting scheme of the filter and the number of iterations. The primary aim of thisstudy is to compare the predictive performances of the final models built on the filtered and the un-filtered training datasets.A case study of software measurement data of a high assurance software project is performed. It is shown that predictiveperformances of models built on the filtered fit datasets and evaluated on a noisy test dataset are generally better than thosebuilt on the noisy (un-filtered) fit dataset. However, predictive performance based on certain aggressive filters is affected bypresence of noise in the evaluation dataset.
Improved Design Techniques for Switched-Capacitor Ladder Filters.
Hsu, Teng-Hsien
Using the new developments of MOS technology, switched-capacitor filters which consist of operational amplifiers, capacitors and switches in monolithic form, were widely investigated and put into practical forms. The switched-capacitor ladder filters have derived from doubly-terminated reactance two-ports. The main part of this dissertation is aimed at improving the efficiency and eliminating some shortcomings of the bilinear design technique. Two novel input stages which incorporate the necessary sample-and-hold function into the bilinear ladder filters are presented. The circuits are insensitive to parasitic capacitances. Some techniques to reduce the number of operational amplifier for bilinear switched-capacitor ladder filters are given. The number of top-plate parasitic-sensitive capacitors is less than in any of the existing design techniques. The clock feedthrough effects of pseudo-N-path switched-capacitor filter using lowpass filters as path filters are eliminated by the improved technique with doubling the number of operational amplifiers. Two-phase pseudo -N-path switched-capacitor filters can be obtained by tripling the number of operational amplifiers. The design technique for extending bilinear lowpass switched-capacitor ladder filters from odd orders to even orders is presented. One of the factors limiting the speed of bilinear switched-capacitor ladder filters is the delay-free loops. The techniques for breaking delay-free loops of low-order switched -capacitor filters are introduced. Digital ladder filters can be obtained through those switched-capacitor filters without delay-free loops. Numerical examples are given to compare the following digital filters: general cascade realization, wave digital filter, the digital filters derived from switched-capacitor filters - cascade and ladder. An improved high speed switched-capacitor linear interpolator, and nonlinear interpolators are described. The circuits are completely parasitic-insensitive. Two
Distortion Parameters Analysis Method Based on Improved Filtering Algorithm
Directory of Open Access Journals (Sweden)
ZHANG Shutuan
2013-10-01
Full Text Available In order to realize the accurate distortion parameters test of aircraft power supply system, and satisfy the requirement of corresponding equipment in the aircraft, the novel power parameters test system based on improved filtering algorithm is introduced in this paper. The hardware of the test system has the characters of s portable and high-speed data acquisition and processing, and the software parts utilize the software Labwindows/CVI as exploitation software, and adopt the pre-processing technique and adding filtering algorithm. Compare with the traditional filtering algorithm, the test system adopted improved filtering algorithm can help to increase the test accuracy. The application shows that the test system with improved filtering algorithm can realize the accurate test results, and reach to the design requirements.
Improved expressions for performance parameters for complex filters.
Sheppard, Colin J R; Ledesma, Silvia; Campos, Juan; Escalera, Juan C
2007-06-15
Improved expressions are given for the performance parameters for transverse and axial gains for complex pupil filters. These expressions can be used to predict the behavior of filters that give a small axial shift in the focal intensity maximum and also predict the changes in gain for different observation planes.
Improved Distributed Particle Filter for Simultaneous Localization and Mapping
Directory of Open Access Journals (Sweden)
Mei Wu
2013-07-01
Full Text Available The Simultaneous localization and mapping (SLAM problem have become a focus of many researches on robot navigation. Generally the most widely used filter in SLAM problems are centralized filter. It is well known that SLAM based on conventional centralized filter must reconfigure the entire state vectors when the observation dimension changes, which cause an exponential growth in computation quantities and difficulties in isolate potential faults. In this paper, we proposed improved DPF distributed particle filter-SLAM in two aspects, in DPF-SLAM one centralized filter is divided into several distributed filters which reduce the computation quantities efficiently and avoid the necessary to reconfigure the entire state vectors in every step. First, we improved the important function of the local filters in distributed particle filter. By changed a set constant in the important function to an adaptive value, we improved the robustness of the system. Second, we propose an information fusion method that mixed the innovation method and the number of effective particles method, which combined the advantages of these two methods. The result of simulations shows that the algorithms we proposed improved the virtue of the DPF-SLAM system in isolate faults and enabled the system has a better tolerance and robustness.
Improved multilevel filters to enhance infrared small target
Institute of Scientific and Technical Information of China (English)
Xiaoping Wang; Tianxu Zhang; Luxin Yan; Man Wang; Jiawei Wu
2011-01-01
We propose improved multilevel filters (IMLFs) involving the absolute value operation into the algorithmic framework of traditional multilevel filters (MLFs) to improve the robustness of infrared small target enhancement techniques under a complex infrared cluttered background. Compared with the widely used small target enhancement methods which only deal with bright targets, the proposed technique can enhance the infrared small target, whether it is bright or dark. Experimental results verify that the proposed technique is efficient and practical.%@@ We propose improved multilevel filters (IMLFs) involving the absolute value operation into the algorithmic framework of traditional multilevel filters (MLFs) to improve the robustness of infrared small target enhancement techniques under a complex infrared cluttered background.Compared with the widely used small target enhancement methods which only deal with bright targets, the proposed technique can enhance the infrared small target, whether it is bright or dark.Experimental results verify that the proposed technique is efficient and practical.
Multispectral Imager With Improved Filter Wheel and Optics
Bremer, James C.
2007-01-01
Figure 1 schematically depicts an improved multispectral imaging system of the type that utilizes a filter wheel that contains multiple discrete narrow-band-pass filters and that is rotated at a constant high speed to acquire images in rapid succession in the corresponding spectral bands. The improvement, relative to prior systems of this type, consists of the measures taken to prevent the exposure of a focal-plane array (FPA) of photodetectors to light in more than one spectral band at any given time and to prevent exposure of the array to any light during readout. In prior systems, these measures have included, variously the use of mechanical shutters or the incorporation of wide opaque sectors (equivalent to mechanical shutters) into filter wheels. These measures introduce substantial dead times into each operating cycle intervals during which image information cannot be collected and thus incoming light is wasted. In contrast, the present improved design does not involve shutters or wide opaque sectors, and it reduces dead times substantially. The improved multispectral imaging system is preceded by an afocal telescope and includes a filter wheel positioned so that its rotation brings each filter, in its turn, into the exit pupil of the telescope. The filter wheel contains an even number of narrow-band-pass filters separated by narrow, spoke-like opaque sectors. The geometric width of each filter exceeds the cross-sectional width of the light beam coming out of the telescope. The light transmitted by the sequence of narrow-band filters is incident on a dichroic beam splitter that reflects in a broad shorter-wavelength spectral band that contains half of the narrow bands and transmits in a broad longer-wavelength spectral band that contains the other half of the narrow spectral bands. The filters are arranged on the wheel so that if the pass band of a given filter is in the reflection band of the dichroic beam splitter, then the pass band of the adjacent filter
Improvement of ISOM by using filter
Directory of Open Access Journals (Sweden)
Imen Chaabouni
2012-05-01
Full Text Available Image compression helps in storing the transmitted data in proficient way by decreasing its redundancy. This technique helps in transferring more digital or multimedia data over internet as it increases the storage space. It is important to maintain the image quality even if it is compressed to certain extent. Depend upon this the image compression is classified into two categories : lossy and lossless image compression. There are many lossy digital image compression techniques exists. Among this Incremental Self Organizing Map is a familiar one. The good pictures quality can be retrieved if image denoising technique is used for compression and also provides better compression ratio. Image denoising is an important pre-processing step for many image analysis and computer vision system. It refers to the task of recovering a good estimate of the true image from a degraded observation without altering and changing useful structure in the image such as discontinuities and edges. Many approaches have been proposed to remove the noise effectively while preserving the original image details and features as much as possible. This paper proposes a technique for image compression using Incremental Self Organizing Map (ISOM with Discret Wavelet Transform (DWT by applying filtering techniques which play a crucial role in enhancing the quality of a reconstructed image. The experimental result shows that the proposed technique obtained better compression ratio value.
An Improved Unscented Particle Filter with Global Sampling Strategy
Directory of Open Access Journals (Sweden)
Yi-zheng Zhao
2014-01-01
Full Text Available Particle filter (PF has many variations and one of the most popular is the unscented particle filter (UPF. UPF uses the unscented Kalman filter (UKF to generate particles in the PF framework and has a better performance than the standard PF. However, UPF suffers from its high computation complexity because it has to execute UKF to each particle to obtain proposal distribution. This paper gives an improved UPF aiming at reducing the computation complexity of the algorithm. In comparison to the standard UPF, the new strategy generates proposal distribution from the mean and covariance value of the whole particles instead of from each particle. Thus the improved algorithm utilizes the characteristics of the whole particles and only needs to perform UKF algorithm once to get the proposal distribution at each time step. Experimental results show that, compared to standard UPF, the improved algorithm reduces the time consumption greatly almost without performance degradation.
PARTICLE FILTER BASED VEHICLE TRACKING APPROACH WITH IMPROVED RESAMPLING STAGE
Directory of Open Access Journals (Sweden)
Wei Leong Khong
2014-02-01
Full Text Available Optical sensors based vehicle tracking can be widely implemented in traffic surveillance and flow control. The vast development of video surveillance infrastructure in recent years has drawn the current research focus towards vehicle tracking using high-end and low cost optical sensors. However, tracking vehicles via such sensors could be challenging due to the high probability of changing vehicle appearance and illumination, besides the occlusion and overlapping incidents. Particle filter has been proven as an approach which can overcome nonlinear and non-Gaussian situations caused by cluttered background and occlusion incidents. Unfortunately, conventional particle filter approach encounters particle degeneracy especially during and after the occlusion. Particle filter with sampling important resampling (SIR is an important step to overcome the drawback of particle filter, but SIR faced the problem of sample impoverishment when heavy particles are statistically selected many times. In this work, genetic algorithm has been proposed to be implemented in the particle filter resampling stage, where the estimated position can converge faster to hit the real position of target vehicle under various occlusion incidents. The experimental results show that the improved particle filter with genetic algorithm resampling method manages to increase the tracking accuracy and meanwhile reduce the particle sample size in the resampling stage.
Improving search filter development: a study of palliative care literature
Directory of Open Access Journals (Sweden)
Tieman Jennifer
2007-06-01
Full Text Available Abstract Background It is difficult to systematically search for literature relevant to palliative care in general medical journals. A previously developed search filter for use on OVID Medline validated using a gold standard set of references identified through hand searching, achieved an unacceptably low sensitivity (45.4%. Retrieving relevant literature is integral to support evidence based practice, and understanding the nature of the incorrectly excluded citations (false negatives using the filter may lead to improvement in the filter's performance. Methods The objectives were to describe the nature of subjects reflected in the false negative citations and to empirically improve the sensitivity of the search filter. A thematic analysis of MeSH terms by three independent reviewers was used to describe the subject coverage of the missed records. Using a frequency analysis of MeSH terms, those headings which could individually contribute at least 2.5% to sensitivity (occurring 19 or more times were added to the search filter. All previously run searches were rerun at the same time as the revised filter, and results compared. Results Thematic analysis of MeSH terms identified thirteen themes reflected in the missing records, none of them intrinsically palliative. The addition of six MeSH terms to the existing search filter (physician-patient relations, prognosis, quality of life, survival rate, treatment outcome and attitude to health led to an increase in sensitivity from 46.3% to 64.7%, offset by a decrease in precision from 72.6% to 21.9%. Conclusion The filter's sensitivity was successfully increased using frequency analysis of MeSH terms, offset by a decrease in precision. A thematic analysis of MeSH terms for the false negative citations confirmed the absence of any intrinsically palliative theme or term, suggesting that future improvements to search filters for palliative care literature will first depend on better identifying how
An Improved Particle Filter for Service Robot Self-Localization
Cen, Guanghui; Matsuhira, Nobuto; Hirokawa, Junko; Ogawa, Hideki; Hagiwara, Ichiro
Mobile robot localization is a problem of determining a robot's pose in an environment, which is also one of the most basic problems in mobile robot applications. Recently, introduction of particle filters becomes the most popular approach in mobile robot localization and has been applied with great success to a variety of state estimation problems. In this paper, an particle filter is applied in the authors' service robot position tracking and global localization. Moreover, the posterior distribution of a robot pose in global localization is usually a multi-model due to the symmetry of the environment and ambiguous detected features. Considering these characteristics, we propose an improved cluster particle filter to increase the global localization robustness and accuracy. On-line experiments based detailed analysis of coordinate errors and algorithm efficiency are given. On-line experimental results also show the efficiency and robustness of the approach in the authors' service robot ApriAlpha™ Platform.
Improved hybrid information filtering based on limited time window
Song, Wen-Jun; Guo, Qiang; Liu, Jian-Guo
2014-12-01
Adopting the entire collecting information of users, the hybrid information filtering of heat conduction and mass diffusion (HHM) (Zhou et al., 2010) was successfully proposed to solve the apparent diversity-accuracy dilemma. Since the recent behaviors are more effective to capture the users' potential interests, we present an improved hybrid information filtering of adopting the partial recent information. We expand the time window to generate a series of training sets, each of which is treated as known information to predict the future links proven by the testing set. The experimental results on one benchmark dataset Netflix indicate that by only using approximately 31% recent rating records, the accuracy could be improved by an average of 4.22% and the diversity could be improved by 13.74%. In addition, the performance on the dataset MovieLens could be preserved by considering approximately 60% recent records. Furthermore, we find that the improved algorithm is effective to solve the cold-start problem. This work could improve the information filtering performance and shorten the computational time.
Improved HEPA Filter Technology for Flexible and Rigid Containment Barriers
Energy Technology Data Exchange (ETDEWEB)
Pinson, Paul Arthur
1998-07-01
Safety and reliability in glovebox operations can be significantly improved and waste packaging efficiencies can be increased by inserting flexible, lightweight, high capacity HEPA filters into the walls of plastic sheet barriers. This HEPA filter/barrier technology can be adapted to a wide variety of applications: disposable waste bags, protective environmental barriers for electronic equipment, single or multiple use glovebag assemblies, flexible glovebox wall elements, and room partitions. These reliable and inexpensive filtered barriers have many uses in fields such as radioactive waste processing, HVAC filter changeout, vapor or grit blasting, asbestos cleanup, pharmaceutical, medical, biological, and electronic equipment containment. The applications can result in significant cost savings, improved operational reliability and safety, and total waste volume reduction. This technology was developed at the Argonne National Laboratory-West (ANL-W) in 1993 and has been used at ANL-W since then at the TRU Waste Characterization Chamber Gloveboxes. Another 1998 AGS Conference paper titled "TRU Waste Characterization Gloveboxes", presented by Mr. David Duncan of ANL-W, describes these boxes.
Bioenergy and biofertilizer : improvement of biogas production from filter cake
Energy Technology Data Exchange (ETDEWEB)
Fonte, A.H. [Environmental Bioremediation Group, Research and Development Agency, GeoCuba, Camaguey (Cuba); Alvarez, R.C. [Provincial Direction of Soils, Camaguey (Cuba)
2000-07-01
The anaerobic digestion of sugar mill filter cake (SMFC) was studied using a natural zeolite to intensify the biogas production. The anaerobic digestion (AD) of agricultural waste mixtures in certain proportions is the underlying basis of biogas generation. Earlier studies have shown that certain inert materials can act as stimulators in biogas production when used in conjunction with AD. This study involved three experiments using filter cake from different sugar mills using three doses of zeolite to determine how they stimulate biogas production. Another objective of the study was to determine if the mud of the digester containing the added zeolite has an impact on plants and soil. The study was conducted under glass house conditions using a brown soil with carbonates with neutral pH and high contents of P{sub 2}O{sub 5}, K{sub 2}O and organic matter. It was concluded that it is possible to increase the biogas yield and to improve AD behaviour of the filter cake by using a zeolite adapted to unique operating conditions. The amount of yield depends on the origin of the filter cake, the stimulator dose and age. Results were in the order of 20-40 per cent biogas production. Fresh filter cake was found to produce more biogas. The mud of the anaerobic digestion of the filter cake containing zeolite positively impacted on the agronomic behaviour of the sorghum in relation to P{sub 2}O{sub 5}, K{sub 2}O and organic matter content. 19 refs., 4 tabs.
Improvement of QR Code Recognition Based on Pillbox Filter Analysis
Directory of Open Access Journals (Sweden)
Jia-Shing Sheu
2013-04-01
Full Text Available The objective of this paper is to perform the innovation design for improving the recognition of a captured QR code image with blur through the Pillbox filter analysis. QR code images can be captured by digital video cameras. Many factors contribute to QR code decoding failure, such as the low quality of the image. Focus is an important factor that affects the quality of the image. This study discusses the out-of-focus QR code image and aims to improve the recognition of the contents in the QR code image. Many studies have used the pillbox filter (circular averaging filter method to simulate an out-of-focus image. This method is also used in this investigation to improve the recognition of a captured QR code image. A blurred QR code image is separated into nine levels. In the experiment, four different quantitative approaches are used to reconstruct and decode an out-of-focus QR code image. These nine reconstructed QR code images using methods are then compared. The final experimental results indicate improvements in identification.
Improved Collaborative Filtering Recommendation Based on Classification and User Trust
Institute of Scientific and Technical Information of China (English)
Xiao-Lin Xu; Guang-Lin Xu
2016-01-01
When dealing with the ratings from users, traditional collaborative filtering algorithms do not consider the credibility of rating data, which affects the accuracy of similarity. To address this issue, the paper proposes an improved algorithm based on classification and user trust. It firstly classifies all the ratings by the categories of items. And then, for each category, it evaluates the trustworthy degree of each user on the category and imposes the degree on the ratings of the user. Finally, the algorithm explores the similarities between users, finds the nearest neighbors, and makes recommendations within each category. Simulations show that the improved algorithm outperforms the traditional collaborative filtering algorithms and enhances the accuracy of recommendation.
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.
Improvements of Analog Neural Networks Based on Kalman Filter
Directory of Open Access Journals (Sweden)
Z. Raida
2002-04-01
Full Text Available In the paper, original improvements of recurrent analog neuralnetworks, which are based on Kalman filter, are presented. Theseimprovements eliminate some disadvantages of the classical Kalmanneural network and enable a real time processing of quickly changingsignals, which appear in adaptive antennas and similar applications.This goal is reached using such circuit elements, which increase theconvergence rate of the network and decrease the dependence ofconvergence rate on the ratio of eigenvalues of the correlation matrixof input signals.
Guionnet, A
2012-01-01
By solving a free analog of the Monge-Amp\\`ere equation, we prove a non-commutative analog of Brenier's monotone transport theorem: if an $n$-tuple of self-adjoint non-commutative random variables $Z_{1},...,Z_{n}$ satisfies a regularity condition (its conjugate variables $\\xi_{1},...,\\xi_{n}$ should be analytic in $Z_{1},...,Z_{n}$ and $\\xi_{j}$ should be close to $Z_{j}$ in a certain analytic norm), then there exist invertible non-commutative functions $F_{j}$ of an $n$-tuple of semicircular variables $S_{1},...,S_{n}$, so that $Z_{j}=F_{j}(S_{1},...,S_{n})$. Moreover, $F_{j}$ can be chosen to be monotone, in the sense that $F_{j}=\\mathscr{D}_{j}g$ and $g$ is a non-commutative function with a positive definite Hessian. In particular, we can deduce that $C^{*}(Z_{1},...,Z_{n})\\cong C^{*}(S_{1},...,S_{n})$ and $W^{*}(Z_{1},...,Z_{n})\\cong L(\\mathbb{F}(n))$. Thus our condition is a useful way to recognize when an $n$-tuple of operators generate a free group factor. We obtain as a consequence that the q-deforme...
Improvement of QR Code Recognition Based on Pillbox Filter Analysis
Jia-Shing Sheu; Kai-Chung Teng
2013-01-01
The objective of this paper is to perform the innovation design for improving the recognition of a captured QR code image with blur through the Pillbox filter analysis. QR code images can be captured by digital video cameras. Many factors contribute to QR code decoding failure, such as the low quality of the image. Focus is an important factor that affects the quality of the image. This study discusses the out-of-focus QR code image and aims to improve the recognition of the conte...
Lee, Woong-Bi; Kim, Cheolsun; Ju, Gun Wu; Lee, Yong Tak; Lee, Heung-No
2016-05-01
Miniature spectrometers have been widely developed in various academic and industrial applications such as bio-medical, chemical and environmental engineering. As a family of spectrometers, optical filter-array based spectrometers fabricated using CMOS or Nano technology provide miniaturization, superior portability and cost effectiveness. In filterarray based spectrometers, the resolution which represents the ability how closely resolve two neighboring spectra, depends on the number of filters and the characteristics of the transmission functions (TFs) of the filters. In practice, due to the small-size and low-cost fabrication, the number of filters is limited and the shape of the TF of each filter is nonideal. As a development of modern digital signal processing (DSP), the spectrometers are equipped with DSP algorithms not only to alleviate distortions due to unexpected noise or interferences among filters but also reconstruct the original signal spectrum. For a high-resolution spectrum reconstruction by the DSP, the TFs of the filters need to be sufficiently uncorrelated with each other. In this paper, we present a design of optical thin-film filters which have the uncorrelated TFs. Each filter consists of multiple layers of high- and low-refractive index materials deposited on a substrate. The proposed design helps the DSP algorithm to improve resolution with a small number of filters. We demonstrate that a resolution of 5 nm within a range from 500 nm to 1100 nm can be achieved with only 64 filters.
Improving arterial spin labeling data by temporal filtering
Petr, Jan; Ferre, Jean-Christophe; Gauvrit, Jean-Yves; Barillot, Christian
2010-03-01
Arterial spin labeling (ASL) is an MRI method for imaging brain perfusion by magnetically labeling blood in brain feeding arteries. The perfusion is obtained from the difference between images with and without prior labeling. Image noise is one of the main problems of ASL as the difference is around 0.5-2% of the image magnitude. Usually, 20-40 pairs of images need to be acquired and averaged to reach a satisfactory quality. The images are acquired shortly after the labeling to allow the labeled blood to reach the imaged slice. A sequence of images with multiple delays is more suitable for quantification of the cerebral blood flow as it gives more information about the blood arrival and relaxation. Although the quantification methods are sensitive to noise, no filtering or only Gaussian filtering is used to denoise the data in the temporal domain prior to quantification. In this article, we propose an efficient way to use the redundancy of information in the time sequence of each pixel to suppress noise. For this purpose, the vectorial NL-means method is adapted to work in the temporal domain. The proposed method is tested on simulated and real 3T MRI data. We demonstrate a clear improvement of the image quality as well as a better performance compared to Gaussian and normal spatial NL-means filtering.
Improved Multistage Wiener Filters in Nonhomogeneous Clutter Environments
Institute of Scientific and Technical Information of China (English)
Bin Tang; Xue-Gang Wang; Ke-Song Chen
2008-01-01
A new method combining space-time preprocessing with multistage Wiener filters (STPMWF) is proposed to improve the performance of space-time adaptive processing (STAP) in nonhomogeneous clutter scenario. The new scheme only requires the data from the primary range bin, thus it can suppress discrete interferers efficiently, without calculating the inverse of covariance matrix. Comparing to the original MWF approach, the proposed scheme can be regarded as practical solutions for robust and effective STAP of nonhomogeneous radar data. The theoretical analysis shows that our STPMWF is simple in implementation and fast in convergence. The numeric results by using simulated data exhibit a good agreement with the proposed theory.
Constraining the Ensemble Kalman Filter for improved streamflow forecasting
Maxwell, Deborah; Jackson, Bethanna; McGregor, James
2016-04-01
Data assimilation techniques such as the Kalman Filter and its variants are often applied to hydrological models with minimal state volume/capacity constraints. Flux constraints are rarely, if ever, applied. Consequently, model states can be adjusted beyond physically reasonable limits, compromising the integrity of model output. In this presentation, we investigate the effect of constraining the Ensemble Kalman Filter (EnKF) on forecast performance. An EnKF implementation with no constraints is compared to model output with no assimilation, followed by a 'typical' hydrological implementation (in which mass constraints are enforced to ensure non-negativity and capacity thresholds of model states are not exceeded), and then a more tightly constrained implementation where flux as well as mass constraints are imposed to limit the rate of water movement within a state. A three year period (2008-2010) with no significant data gaps and representative of the range of flows observed over the fuller 1976-2010 record was selected for analysis. Over this period, the standard implementation of the EnKF (no constraints) contained eight hydrological events where (multiple) physically inconsistent state adjustments were made. All were selected for analysis. Overall, neither the unconstrained nor the "typically" mass-constrained forecasts were significantly better than the non-filtered forecasts; in fact several were significantly degraded. Flux constraints (in conjunction with mass constraints) significantly improved the forecast performance of six events relative to all other implementations, while the remaining two events showed no significant difference in performance. We conclude that placing flux as well as mass constraints on the data assimilation framework encourages physically consistent state updating and results in more accurate and reliable forward predictions of streamflow for robust decision-making. We also experiment with the observation error, and find that this
Improving Bloom Filter Performance on Sequence Data Using k-mer Bloom Filters.
Pellow, David; Filippova, Darya; Kingsford, Carl
2017-06-01
Using a sequence's k-mer content rather than the full sequence directly has enabled significant performance improvements in several sequencing applications, such as metagenomic species identification, estimation of transcript abundances, and alignment-free comparison of sequencing data. As k-mer sets often reach hundreds of millions of elements, traditional data structures are often impractical for k-mer set storage, and Bloom filters (BFs) and their variants are used instead. BFs reduce the memory footprint required to store millions of k-mers while allowing for fast set containment queries, at the cost of a low false positive rate (FPR). We show that, because k-mers are derived from sequencing reads, the information about k-mer overlap in the original sequence can be used to reduce the FPR up to 30 × with little or no additional memory and with set containment queries that are only 1.3 - 1.6 times slower. Alternatively, we can leverage k-mer overlap information to store k-mer sets in about half the space while maintaining the original FPR. We consider several variants of such k-mer Bloom filters (kBFs), derive theoretical upper bounds for their FPR, and discuss their range of applications and limitations.
Decadal climate predictions improved by ocean ensemble dispersion filtering
Kadow, C.; Illing, S.; Kröner, I.; Ulbrich, U.; Cubasch, U.
2017-06-01
Decadal predictions by Earth system models aim to capture the state and phase of the climate several years in advance. Atmosphere-ocean interaction plays an important role for such climate forecasts. While short-term weather forecasts represent an initial value problem and long-term climate projections represent a boundary condition problem, the decadal climate prediction falls in-between these two time scales. In recent years, more precise initialization techniques of coupled Earth system models and increased ensemble sizes have improved decadal predictions. However, climate models in general start losing the initialized signal and its predictive skill from one forecast year to the next. Here we show that the climate prediction skill of an Earth system model can be improved by a shift of the ocean state toward the ensemble mean of its individual members at seasonal intervals. We found that this procedure, called ensemble dispersion filter, results in more accurate results than the standard decadal prediction. Global mean and regional temperature, precipitation, and winter cyclone predictions show an increased skill up to 5 years ahead. Furthermore, the novel technique outperforms predictions with larger ensembles and higher resolution. Our results demonstrate how decadal climate predictions benefit from ocean ensemble dispersion filtering toward the ensemble mean.type="synopsis">type="main">Plain Language SummaryDecadal predictions aim to predict the climate several years in advance. Atmosphere-ocean interaction plays an important role for such climate forecasts. The ocean memory due to its heat capacity holds big potential skill. In recent years, more precise initialization techniques of coupled Earth system models (incl. atmosphere and ocean) have improved decadal predictions. Ensembles are another important aspect. Applying slightly perturbed predictions to trigger the famous butterfly effect results in an ensemble. Instead of evaluating one prediction, but the
Method for Improving Indoor Positioning Accuracy Using Extended Kalman Filter
Directory of Open Access Journals (Sweden)
Seoung-Hyeon Lee
2016-01-01
Full Text Available Beacons using bluetooth low-energy (BLE technology have emerged as a new paradigm of indoor positioning service (IPS because of their advantages such as low power consumption, miniaturization, wide signal range, and low cost. However, the beacon performance is poor in terms of the indoor positioning accuracy because of noise, motion, and fading, all of which are characteristics of a bluetooth signal and depend on the installation location. Therefore, it is necessary to improve the accuracy of beacon-based indoor positioning technology by fusing it with existing indoor positioning technology, which uses Wi-Fi, ZigBee, and so forth. This study proposes a beacon-based indoor positioning method using an extended Kalman filter that recursively processes input data including noise. After defining the movement of a smartphone on a flat two-dimensional surface, it was assumed that the beacon signal is nonlinear. Then, the standard deviation and properties of the beacon signal were analyzed. According to the analysis results, an extended Kalman filter was designed and the accuracy of the smartphone’s indoor position was analyzed through simulations and tests. The proposed technique achieved good indoor positioning accuracy, with errors of 0.26 m and 0.28 m from the average x- and y-coordinates, respectively, based solely on the beacon signal.
Does a yellow filter improve visual object categorization in normal aging?
Lenoble, Quentin; Boucart, Muriel; Rougier, Marie-Bénédicte; Bordaberry, Pierre; Delord, Sandrine
2014-01-01
Previous studies have shown that a yellow filter (CPF450) can increase contrast, motion sensitivity, vergence, and accommodation. We investigated whether a yellow filter can reduce age-related visual deficits. We tested two groups of 60 observers (mean age 24 vs. 72) in an object categorization task. Grayscale photographs of natural objects and artifacts were displayed either centrally or peripherally (21°) at low (8%) or medium (30%) contrast. There were three filter conditions (no filter, placebo filter, and yellow filter). Both groups of observers performed similarly on central and medium-contrast pictures. The deleterious effects of reduced contrast and eccentricity were stronger in elderly individuals. Moreover, the yellow filter globally improved the speed of categorization for the elderly participants. The decrease in response time in the yellow filter condition was larger when the stimuli were displayed peripherally in both groups. A yellow filter should be considered as a potential means for visual improvement in normal aging.
Improved Performance by Parametrizing Wavelet Filters for Digital Image Watermarking
Directory of Open Access Journals (Sweden)
Mangaiyarkarasi Palanivel
2012-03-01
Full Text Available In recent years, watermarking has become an attractive field in areas like copyright protection, imageauthentication and biomedical engineering. Many literatures have reported about discrete wavelet transform (DWT watermarking techniques for data security. However, DWT based watermarking schemes are found to be less robust against image processing attacks. In this paper, an attempt is made to develop a scheme based on Redundant Discrete Wavelet Transform (RDWT. The robustness and security of the proposed RDWT scheme is improved by parametrizing the scaling and wavelet filters by Pollen’s parametrizing technique. An Independent Component Analysis (ICA based detector is also applied, whichextracts watermark directly in spatial domain rather than in transform domain. The unique feature of ICA is that it does not require any transformation during extraction. The results reveal that the proposedscheme produces high peak signal to noise ratio (PSNR values and similarity measure under various image processing attacks.
Directory of Open Access Journals (Sweden)
Wei Zhu
2016-06-01
Full Text Available In order to improve the tracking accuracy, model estimation accuracy and quick response of multiple model maneuvering target tracking, the interacting multiple models five degree cubature Kalman filter (IMM5CKF is proposed in this paper. In the proposed algorithm, the interacting multiple models (IMM algorithm processes all the models through a Markov Chain to simultaneously enhance the model tracking accuracy of target tracking. Then a five degree cubature Kalman filter (5CKF evaluates the surface integral by a higher but deterministic odd ordered spherical cubature rule to improve the tracking accuracy and the model switch sensitivity of the IMM algorithm. Finally, the simulation results demonstrate that the proposed algorithm exhibits quick and smooth switching when disposing different maneuver models, and it also performs better than the interacting multiple models cubature Kalman filter (IMMCKF, interacting multiple models unscented Kalman filter (IMMUKF, 5CKF and the optimal mode transition matrix IMM (OMTM-IMM.
Zhu, Wei; Wang, Wei; Yuan, Gannan
2016-06-01
In order to improve the tracking accuracy, model estimation accuracy and quick response of multiple model maneuvering target tracking, the interacting multiple models five degree cubature Kalman filter (IMM5CKF) is proposed in this paper. In the proposed algorithm, the interacting multiple models (IMM) algorithm processes all the models through a Markov Chain to simultaneously enhance the model tracking accuracy of target tracking. Then a five degree cubature Kalman filter (5CKF) evaluates the surface integral by a higher but deterministic odd ordered spherical cubature rule to improve the tracking accuracy and the model switch sensitivity of the IMM algorithm. Finally, the simulation results demonstrate that the proposed algorithm exhibits quick and smooth switching when disposing different maneuver models, and it also performs better than the interacting multiple models cubature Kalman filter (IMMCKF), interacting multiple models unscented Kalman filter (IMMUKF), 5CKF and the optimal mode transition matrix IMM (OMTM-IMM).
Monotone partitions and almost partitions
Bonanzinga, M.; Cammaroto, F.; van Mill, J.; Pansera, B.A.
2014-01-01
In this paper we are interested in monotone versions of partitionability of topological spaces and weak versions thereof. We identify several classes of spaces with these properties by constructing trees of open sets with various properties.
LLCL-Filtered Grid Converter with Improved Stability and Robustness
DEFF Research Database (Denmark)
Min, Huang; Wang, Xiongfei; Loh, Poh Chiang
2016-01-01
impedance variations, making its design more challenging. To address these concerns, a new parameter design method for LLCL-filter has been formulated in the paper, which when enforced, guarantees robust and stable grid current control regardless of how the grid conditions change. It is thus an enhanced......LLCL-filter has been proven to introduce more filtering at the converter switching frequency, while using smaller passive components. However, like other higher order filters, it introduces resonance to the grid when used with a grid converter. Its stability and robustness are also affected by grid...... method even with no damping added to the grid converter. The method has been applied to the development of an LLCL-filter for testing in the laboratory with a 5-kW, 400-V, and 50-Hz grid converter. The method can also be applied to the lower order LCL-filter with only a slight modification needed....
An improved filtered spherical harmonic method for transport calculations
Energy Technology Data Exchange (ETDEWEB)
Ahrens, C. [Department of Applied Mathematics and Statistics, Colorado School of Mines, Golden, CO 80401 (United States); Merton, S. [Computational Physics Group, AWE Aldermaston, Berkshire (United Kingdom)
2013-07-01
Motivated by the work of R. G. McClarren, C. D. Hauck, and R. B. Lowrie on a filtered spherical harmonic method, we present a new filter for such numerical approximations to the multi-dimensional transport equation. In several test problems, we demonstrate that the new filter produces results with significantly less Gibbs phenomena than the filter used by McClarren, Hauck and Lowrie. This reduction in Gibbs phenomena translates into propagation speeds that more closely match the correct propagation speed and solutions that have fewer regions where the scalar flux is negative. (authors)
Design of LLCL-filter for grid-connected converter to improve stability and robustness
DEFF Research Database (Denmark)
Huang, Min; Wang, Xiongfei; Loh, Poh Chiang;
2015-01-01
The LLCL-filter has recently emerged into gridconnected converters due to the improved filtering capability which ensuring a smaller physical size. An LLCL -based gridconnected converter has almost the same frequency-response characteristic as that with the traditional LCL-filter within half of t...... for LLCL-filter is given. Both simulations and experimental results are provided through a 5 kW, 380V/50 Hz grid-connected inverter model to validate the theoretical analysis in this paper....
Non toxic additives for improved fabric filter performance
Energy Technology Data Exchange (ETDEWEB)
Bustard, C.J.; Baldrey, K.E.; Ebner, T.G. [ADA Technologies, Inc., Englewood, CO (United States)] [and others
1995-11-01
The overall objective of this three-phase Small Business innovative Research (SBIR) program funded by the Department of Energy pittsburgh Energy Technology Center (PETC) is to commercialize a technology based upon the use of non-toxic, novel flue gas conditioning agents to improve particulate air toxic control and overall fabric filter performance. The ultimate objective of the Phase II program currently in progress is to demonstrate that the candidate additives are successful at full-scale on flue gas from a coal-fired utility boiler. This paper covers bench-scale field tests conducted during the period February through May, 1995. The bench-scale additives testing was conducted on a flue gas slipstream taken upstream of the existing particulate control device at a utility power plant firing a Texas lignite coal. These tests were preceded by extensive testing with additives in the laboratory using a simulated flue gas stream and re-dispersed flyash from the same power plant. The bench-scale field testing was undertaken to demonstrate the performance with actual flue gas of the bet candidate additives previously identified in the laboratory. Results from the bench-scale tests will be used to establish operating parameters for a larger-scale demonstration on either a single baghouse compartment or a full baghouse at the same site.
Improved virus removal in ceramic depth filters modified with MgO.
Michen, Benjamin; Fritsch, Johannes; Aneziris, Christos; Graule, Thomas
2013-02-05
Ceramic filters, working on the depth filtration principle, are known to improve drinking water quality by removing human pathogenic microorganisms from contaminated water. However, these microfilters show no sufficient barrier for viruses having diameters down to 20 nm. Recently, it was shown that the addition of positively charged materials, for example, iron oxyhydroxide, can improve virus removal by adsorption mechanisms. In this work, we modified a common ceramic filter based on diatomaceous earth by introducing a novel virus adsorbent material, magnesium oxyhydroxide, into the filter matrix. Such filters showed an improved removal of about 4-log in regard to bacteriophages MS2 and PhiX174. This is explained with the electrostatic enhanced adsorption approach that is the favorable adsorption of negatively charged viruses onto positively charged patches in an otherwise negatively charged filter matrix. Furthermore, we provide theoretical evidence applying calculations according to Derjaguin-Landau-Verwey-Overbeek theory to strengthen our experimental results. However, modified filters showed a significant variance in virus removal efficiency over the course of long-term filtration experiments with virus removal increasing with filter operation time (or filter aging). This is explained by transformational changes of MgO in the filter upon contact with water. It also demonstrates that filter history is of great concern when filters working on the adsorption principles are evaluated in regard to their retention performance as their surface characteristics may alter with use.
Why Monotonous Repetition is Unsatisfying
Salingaros, Nikos A
2011-01-01
Human beings prefer ordered complexity and not randomness in their environment, a result of our perceptual system evolving to interpret natural forms. We also recognize monotonously repeating forms as unnatural. Although widespread in today's built environment, such forms generate reactions ranging from boredom to unease. Christopher Alexander has introduced rules for generating forms adapted to natural geometries, which show structured variation with multiple symmetries in a hierarchy of scales. It turns out to be impossible to generate monotonously repeating forms by following those rules. As it is highly probable that traditional artifacts, buildings, and cities were created instinctively using a version of the same rules, this is the reason we never find monotonously repeating forms in traditional cultures.
Improvements to Filter Debris Analysis in Aviation Propulsion Systems
2012-12-01
filter patch containing the ferromagnetic debris is typically of most interest as critical oil- wetted components are typically made from ferrous alloys ...are typically manufactured using special steels with specific alloying elements. Elemental analysis using a Scanning electron Microscope (SEM) with...debris patch (left) and extracted ferrous debris patch (right) 2.2.1 Results A total of 48 filters were analysed during the trial from all four
Convex functions, monotone operators and differentiability
Phelps, Robert R
1993-01-01
The improved and expanded second edition contains expositions of some major results which have been obtained in the years since the 1st edition. Theaffirmative answer by Preiss of the decades old question of whether a Banachspace with an equivalent Gateaux differentiable norm is a weak Asplund space. The startlingly simple proof by Simons of Rockafellar's fundamental maximal monotonicity theorem for subdifferentials of convex functions. The exciting new version of the useful Borwein-Preiss smooth variational principle due to Godefroy, Deville and Zizler. The material is accessible to students who have had a course in Functional Analysis; indeed, the first edition has been used in numerous graduate seminars. Starting with convex functions on the line, it leads to interconnected topics in convexity, differentiability and subdifferentiability of convex functions in Banach spaces, generic continuity of monotone operators, geometry of Banach spaces and the Radon-Nikodym property, convex analysis, variational princ...
Monotonicity of social welfare optima
DEFF Research Database (Denmark)
Hougaard, Jens Leth; Østerdal, Lars Peter Raahave
2010-01-01
This paper considers the problem of maximizing social welfare subject to participation constraints. It is shown that for an income allocation method that maximizes a social welfare function there is a monotonic relationship between the incomes allocated to individual agents in a given coalition...... (with at least three members) and its participation constraint if and only if the aggregate income to that coalition is always maximized. An impossibility result demonstrates that there is no welfare maximizing allocation method in which agents' individual incomes monotonically increase in society......'s income. Thus, for any such allocation method, there are situations where some agents have incentives to prevent society in becoming richer....
Improved Bearings-Only Multi-Target Tracking with GM-PHD Filtering
Zhang, Qian; Song, Taek Lyul
2016-01-01
In this paper, an improved nonlinear Gaussian mixture probability hypothesis density (GM-PHD) filter is proposed to address bearings-only measurements in multi-target tracking. The proposed method, called the Gaussian mixture measurements-probability hypothesis density (GMM-PHD) filter, not only approximates the posterior intensity using a Gaussian mixture, but also models the likelihood function with a Gaussian mixture instead of a single Gaussian distribution. Besides, the target birth model of the GMM-PHD filter is assumed to be partially uniform instead of a Gaussian mixture. Simulation results show that the proposed filter outperforms the GM-PHD filter embedded with the extended Kalman filter (EKF) and the unscented Kalman filter (UKF). PMID:27626423
Improved Bearings-Only Multi-Target Tracking with GM-PHD Filtering
Directory of Open Access Journals (Sweden)
Qian Zhang
2016-09-01
Full Text Available In this paper, an improved nonlinear Gaussian mixture probability hypothesis density (GM-PHD filter is proposed to address bearings-only measurements in multi-target tracking. The proposed method, called the Gaussian mixture measurements-probability hypothesis density (GMM-PHD filter, not only approximates the posterior intensity using a Gaussian mixture, but also models the likelihood function with a Gaussian mixture instead of a single Gaussian distribution. Besides, the target birth model of the GMM-PHD filter is assumed to be partially uniform instead of a Gaussian mixture. Simulation results show that the proposed filter outperforms the GM-PHD filter embedded with the extended Kalman filter (EKF and the unscented Kalman filter (UKF.
Directory of Open Access Journals (Sweden)
Plubtieng Somyot
2009-01-01
Full Text Available Abstract We introduce an iterative scheme for finding a common element of the solution set of a maximal monotone operator and the solution set of the variational inequality problem for an inverse strongly-monotone operator in a uniformly smooth and uniformly convex Banach space, and then we prove weak and strong convergence theorems by using the notion of generalized projection. The result presented in this paper extend and improve the corresponding results of Kamimura et al. (2004, and Iiduka and Takahashi (2008. Finally, we apply our convergence theorem to the convex minimization problem, the problem of finding a zero point of a maximal monotone operator and the complementary problem.
Directory of Open Access Journals (Sweden)
Somyot Plubtieng
2009-01-01
Full Text Available We introduce an iterative scheme for finding a common element of the solution set of a maximal monotone operator and the solution set of the variational inequality problem for an inverse strongly-monotone operator in a uniformly smooth and uniformly convex Banach space, and then we prove weak and strong convergence theorems by using the notion of generalized projection. The result presented in this paper extend and improve the corresponding results of Kamimura et al. (2004, and Iiduka and Takahashi (2008. Finally, we apply our convergence theorem to the convex minimization problem, the problem of finding a zero point of a maximal monotone operator and the complementary problem.
Convergence for pseudo monotone semiflows on product ordered topological spaces
Yi, Taishan; Huang, Lihong
In this paper, we consider a class of pseudo monotone semiflows, which only enjoy some weak monotonicity properties and are defined on product-ordered topological spaces. Under certain conditions, several convergence principles are established for each precompact orbit of such a class of semiflows to tend to an equilibrium, which improve and extend some corresponding results already known. Some applications to delay differential equations are presented.
The case for improved HEPA-filter mechanical performance standards revisited
Energy Technology Data Exchange (ETDEWEB)
Ricketts, C.I.; Smith, P.R. [New Mexico State Univ., Las Cruces, NM (United States)
1997-08-01
Under benign operating conditions, High Efficiency Particulate Air (HEPA) filter units serve as reliable and relatively economical components in the air cleaning systems of nuclear facilities worldwide. Despite more than four decades of filter-unit evaluation and improvements, however, the material strength characteristics of the glass fiber filter medium continue to ultimately limit filter functional reliability. In worst-case scenarios involving fire suppression, loss-of-coolant accidents (LOCA`s), or exposure to shock waves or tornado induced flows, rupture of the filter medium of units meeting current qualification standards cannot be entirely ruled out. Even under so-called normal conditions of operation, instances of filter failure reported in the literature leave open questions of filter-unit reliability. Though developments of filter units with improved burst strengths have been pursued outside the United States, support for efforts in this country has been comparatively minimal. This despite user requests for filters with greater moisture resistance, for example. Or the fact that conventional filter designs result in not only the least robust component to be found in a nuclear air cleaning system, but also the one most sensitive to the adverse effects of conditions deviating from those of normal operation. Filter qualification-test specifications of current codes, standards, and regulatory guidelines in the United States are based primarily upon research performed in a 30-year period beginning in the 1950`s. They do not seem to reflect the benefits of the more significant developments and understanding of filter failure modes and mechanisms achieved since that time. One overseas design, based on such knowledge, has proven reliability under adverse operating conditions involving combined and serial challenges. Its widespread use, however, has faltered on a lack of consensus in upgrading filter performance standards. 34 refs., 2 figs., 3 tabs.
Improvement on filterability in the aerobic treatment of carboxymethyl cellulose (CMC wastewater
Directory of Open Access Journals (Sweden)
Qing Pei Ye
2014-01-01
Full Text Available CMC is chemically modified from natural cellulose and widely applied in various industries. CMC wastewater consists mainly of sodium glycolate, sodium chloride and water. With extremely high COD and salinity, high concentration CMC wastewater can’t be biologically treated, but with COD and salinity around 15000 mg/L and 30000 mg/L respectively, low concentration CMC wastewater can be aerobically treated. In a CMC factory, the treatment of low concentration wastewater with aerobic MBR was successful except for one serious problem: poor filterability. Two trial solutions: adding micronutrients and applying MBBR were expected to improve the filterability. In the experiment, adding micronutrients was achieved by mixing filtered natural water into the wastewater, rather than dosing chemicals into it. The treatment efficiency of both solutions was close, but adding micronutrients showed distinguished performance in improving filterability, which includes higher filtration flux and slighter membrane fouling. Adding micronutrients also effectively improved the filterability under severe salinity shock.
A Characterization of Generalized Monotone Normed Cones
Institute of Scientific and Technical Information of China (English)
S.ROMAGUERA; E.A.S(A)NCHEZ-P(E)REZ; O.VALERO
2007-01-01
Let C be a cone and consider a quasi-norm p defined on it. We study the structure of the couple (C, p) as a topological space in the case where the function p is also monotone. We characterize when the topology of a quasi-normed cone can be defined by means of a monotone norm. We also define and study the dual cone of a monotone normed cone and the monotone quotient of a general cone.We provide a decomposition theorem which allows us to write a cone as a direct sum of a monotone subcone that is isomorphic to the monotone quotient and other particular subcone.
Study on Performance Improvement of Oil Paint Image Filter Algorithm Using Parallel Pattern Library
Directory of Open Access Journals (Sweden)
Siddhartha Mukherjee
2014-03-01
Full Text Available This paper gives a detailed study on the performanc e of oil paint image filter algorithm with various parameters applied on an image of RGB model . Oil Paint image processing, being very performance hungry, current research tries to find improvement using parallel pattern library. With increasing kernel-size, the processing time of oil paint image filter algorithm increases exponentially.
Testing Monotonicity of Pricing Kernels
Timofeev, Roman
2007-01-01
In this master thesis a mechanism to test mononicity of empirical pricing kernels (EPK) is presented. By testing monotonicity of pricing kernel we can determine whether utility function is concave or not. Strictly decreasing pricing kernel corresponds to concave utility function while non-decreasing EPK means that utility function contains some non-concave regions. Risk averse behavior is usually described by concave utility function and considered to be a cornerstone of classical behavioral ...
Rigatos, Gerasimos
2016-07-01
The Derivative-free nonlinear Kalman Filter is used for developing a communication system that is based on a chaotic modulator such as the Duffing system. In the transmitter's side, the source of information undergoes modulation (encryption) in which a chaotic signal generated by the Duffing system is the carrier. The modulated signal is transmitted through a communication channel and at the receiver's side demodulation takes place, after exploiting the estimation provided about the state vector of the chaotic oscillator by the Derivative-free nonlinear Kalman Filter. Evaluation tests confirm that the proposed filtering method has improved performance over the Extended Kalman Filter and reduces significantly the rate of transmission errors. Moreover, it is shown that the proposed Derivative-free nonlinear Kalman Filter can work within a dual Kalman Filtering scheme, for performing simultaneously transmitter-receiver synchronisation and estimation of unknown coefficients of the communication channel.
Improvement of natural image search engines results by emotional filtering
Directory of Open Access Journals (Sweden)
Patrice Denis
2016-04-01
Full Text Available With the Internet 2.0 era, managing user emotions is a problem that more and more actors are interested in. Historically, the first notions of emotion sharing were expressed and defined with emoticons. They allowed users to show their emotional status to others in an impersonal and emotionless digital world. Now, in the Internet of social media, every day users share lots of content with each other on Facebook, Twitter, Google+ and so on. Several new popular web sites like FlickR, Picassa, Pinterest, Instagram or DeviantArt are now specifically based on sharing image content as well as personal emotional status. This kind of information is economically very valuable as it can for instance help commercial companies sell more efficiently. In fact, with this king of emotional information, business can made where companies will better target their customers needs, and/or even sell them more products. Research has been and is still interested in the mining of emotional information from user data since then. In this paper, we focus on the impact of emotions from images that have been collected from search image engines. More specifically our proposition is the creation of a filtering layer applied on the results of such image search engines. Our peculiarity relies in the fact that it is the first attempt from our knowledge to filter image search engines results with an emotional filtering approach.
Improved Kalman Filter Method for Measurement Noise Reduction in Multi Sensor RFID Systems
Directory of Open Access Journals (Sweden)
Min Chul Kim
2011-10-01
Full Text Available Recently, the range of available Radio Frequency Identification (RFID tags has been widened to include smart RFID tags which can monitor their varying surroundings. One of the most important factors for better performance of smart RFID system is accurate measurement from various sensors. In the multi-sensing environment, some noisy signals are obtained because of the changing surroundings. We propose in this paper an improved Kalman filter method to reduce noise and obtain correct data. Performance of Kalman filter is determined by a measurement and system noise covariance which are usually called the R and Q variables in the Kalman filter algorithm. Choosing a correct R and Q variable is one of the most important design factors for better performance of the Kalman filter. For this reason, we proposed an improved Kalman filter to advance an ability of noise reduction of the Kalman filter. The measurement noise covariance was only considered because the system architecture is simple and can be adjusted by the neural network. With this method, more accurate data can be obtained with smart RFID tags. In a simulation the proposed improved Kalman filter has 40.1%, 60.4% and 87.5% less Mean Squared Error (MSE than the conventional Kalman filter method for a temperature sensor, humidity sensor and oxygen sensor, respectively. The performance of the proposed method was also verified with some experiments.
Improved Kalman filter method for measurement noise reduction in multi sensor RFID systems.
Eom, Ki Hwan; Lee, Seung Joon; Kyung, Yeo Sun; Lee, Chang Won; Kim, Min Chul; Jung, Kyung Kwon
2011-01-01
Recently, the range of available radio frequency identification (RFID) tags has been widened to include smart RFID tags which can monitor their varying surroundings. One of the most important factors for better performance of smart RFID system is accurate measurement from various sensors. In the multi-sensing environment, some noisy signals are obtained because of the changing surroundings. We propose in this paper an improved Kalman filter method to reduce noise and obtain correct data. Performance of Kalman filter is determined by a measurement and system noise covariance which are usually called the R and Q variables in the Kalman filter algorithm. Choosing a correct R and Q variable is one of the most important design factors for better performance of the Kalman filter. For this reason, we proposed an improved Kalman filter to advance an ability of noise reduction of the Kalman filter. The measurement noise covariance was only considered because the system architecture is simple and can be adjusted by the neural network. With this method, more accurate data can be obtained with smart RFID tags. In a simulation the proposed improved Kalman filter has 40.1%, 60.4% and 87.5% less mean squared error (MSE) than the conventional Kalman filter method for a temperature sensor, humidity sensor and oxygen sensor, respectively. The performance of the proposed method was also verified with some experiments.
Monotonicity of chi-square test statistics
Ryu, Keunkwan
2003-01-01
This paper establishes monotonicity of the chi-square test statistic. As the more efficient parameter estimator is plugged into the test statistic, the degrees of freedom of the resulting chi-square test statistic monotonically increase.
Improved Passive-Damped LCL Filter to Enhance Stability in Grid-Connected Voltage-Source Converters
DEFF Research Database (Denmark)
Beres, Remus Narcis; Wang, Xiongfei; Blaabjerg, Frede;
2015-01-01
This paper proposes an improved passive-damped LCL filter to be used as interface between the grid-connected voltage-source converters and the utility grid. The proposed filter replaces the LCL filter capacitor with a traditional C-type filter with the resonant circuit tuned in such a way that sw...
Performance analysis of improved iterated cubature Kalman filter and its application to GNSS/INS.
Cui, Bingbo; Chen, Xiyuan; Xu, Yuan; Huang, Haoqian; Liu, Xiao
2017-01-01
In order to improve the accuracy and robustness of GNSS/INS navigation system, an improved iterated cubature Kalman filter (IICKF) is proposed by considering the state-dependent noise and system uncertainty. First, a simplified framework of iterated Gaussian filter is derived by using damped Newton-Raphson algorithm and online noise estimator. Then the effect of state-dependent noise coming from iterated update is analyzed theoretically, and an augmented form of CKF algorithm is applied to improve the estimation accuracy. The performance of IICKF is verified by field test and numerical simulation, and results reveal that, compared with non-iterated filter, iterated filter is less sensitive to the system uncertainty, and IICKF improves the accuracy of yaw, roll and pitch by 48.9%, 73.1% and 83.3%, respectively, compared with traditional iterated KF.
Improved Aerobic Colony Count Technique for Hydrophobic Grid Membrane Filters
Parrington, Lorna J.; Sharpe, Anthony N.; Peterkin, Pearl I.
1993-01-01
The AOAC International official action procedure for performing aerobic colony counts on hydrophobic grid membrane filters (HGMFs) uses Trypticase soy-fast green FCF agar (FGA) incubated for 48 h. Microbial growths are various shades of green on a pale green background, which can cause problems for automated as well as manual counting. HGMFs which had been incubated 24 or 48 h at 35°C on Trypticase soy agar were flooded underneath with 1 to 2 ml of 0.1% triphenyltetrazolium chloride (TTC) sol...
Some Generalizations of Monotonicity Condition and Applications
Institute of Scientific and Technical Information of China (English)
虞旦盛; 周颂平
2006-01-01
@@ O Introduction It is well known that there are a great number of interesting results in Fourier analysis established by assuming monotonicity of coefficients, and many of them have been generalized by loosing the condition to quasi-monotonicity, O-regularly varying quasi-monotonicity, etc..
Kuenzel, Thomas; Nerlich, Jana; Wagner, Hermann; Rübsamen, Rudolf; Milenkovic, Ivan
2015-01-01
Spherical bushy cells (SBCs) of the anteroventral cochlear nucleus (AVCN) receive input from large excitatory auditory nerve (AN) terminals, the endbulbs of Held, and mixed glycinergic/GABAergic inhibitory inputs. The latter have sufficient potency to block action potential firing in vivo and in slice recordings. However, it is not clear how well the data from slice recordings match the inhibition in the intact brain and how it contributes to complex phenomena such as non-monotonic rate-level functions (RLF). Therefore, we determined the input-output relationship of a model SBC with simulated endbulb inputs and a dynamic inhibitory conductance constrained by recordings in brain slice preparations of hearing gerbils. Event arrival times from in vivo single-unit recordings in gerbils, where 70% of SBC showed non-monotonic RLF, were used as input for the model. Model output RLFs systematically changed from monotonic to non-monotonic shape with increasing strength of tonic inhibition. A limited range of inhibitory synaptic properties consistent with the slice data generated a good match between the model and recorded RLF. Moreover, tonic inhibition elevated the action potentials (AP) threshold and improved the temporal precision of output functions in a SBC model with phase-dependent input conductance. We conclude that activity-dependent, summating inhibition contributes to high temporal precision of SBC spiking by filtering out weak and poorly timed EPSP. Moreover, inhibitory parameters determined in slice recordings provide a good estimate of inhibitory mechanisms apparently active in vivo.
Improved aerobic colony count technique for hydrophobic grid membrane filters.
Parrington, L J; Sharpe, A N; Peterkin, P I
1993-09-01
The AOAC International official action procedure for performing aerobic colony counts on hydrophobic grid membrane filters (HGMFs) uses Trypticase soy-fast green FCF agar (FGA) incubated for 48 h. Microbial growths are various shades of green on a pale green background, which can cause problems for automated as well as manual counting. HGMFs which had been incubated 24 or 48 h at 35 degrees C on Trypticase soy agar were flooded underneath with 1 to 2 ml of 0.1% triphenyltetrazolium chloride (TTC) solution by simply lifting one corner of the filter while it was still on the agar and adding the reagent. Microbial growths on HGMFs were counted after color had been allowed to develop for 15 min at room temperature. With representative foods, virtually all colonies stained pink to red. Automated electronic counts made by using the MI-100 HGMF Interpreter were easier and more reliable than control HGMF counts made by the AOAC International official action procedure. Manual counting was easier as well because of increased visibility of the microbial growths. Except in the case of dairy products, 24-h TTC counts did not differ significantly from 48-h FGA counts, whereas the FGA counts at 24 h were always significantly lower, indicating that for many food products the HGMF TTC flooding method permits aerobic colony counts to be made after 24 h.
Combining docking with pharmacophore filtering for improved virtual screening
Directory of Open Access Journals (Sweden)
Peach Megan L
2009-05-01
Full Text Available Abstract Background Virtual screening is used to distinguish potential leads from inactive compounds in a database of chemical samples. One method for accomplishing this is by docking compounds into the structure of a receptor binding site in order to rank-order compounds by the quality of the interactions they form with the receptor. It is generally established that docking can be reasonably successful at generating good poses of a ligand in an active site. However, the scoring functions that are used with docking are typically not successful at correctly ranking ligands according to binding affinity or even distinguishing correct poses of a given ligand from incorrect ones. Results We have developed a simple method for reducing the number of false positives in a virtual screen, meaning ligands which are scored highly by the docking program but do not bind well in reality. This method uses a docking program for pose generation without regard to scoring, followed by filtering with receptor-based pharmacophore searches. We applied it to three test-case targets: neuraminidase A, cyclin-dependent kinase 2, and the C1 domain of protein kinase C. Conclusion The pharmacophore filtering method can perform better than more traditional docking + scoring methods, and allows the advantages of both docking-based and pharmacophore-based approaches to virtual screening to be fully realized.
Directory of Open Access Journals (Sweden)
Eduardo Fernández
2010-01-01
Full Text Available In this paper, the fast least-mean-squares (LMS algorithm was used to both eliminate noise corrupting the important information coming from a piezoresisitive accelerometer for automotive applications, and improve the convergence rate of the filtering process based on the conventional LMS algorithm. The response of the accelerometer under test was corrupted by process and measurement noise, and the signal processing stage was carried out by using both conventional filtering, which was already shown in a previous paper, and optimal adaptive filtering. The adaptive filtering process relied on the LMS adaptive filtering family, which has shown to have very good convergence and robustness properties, and here a comparative analysis between the results of the application of the conventional LMS algorithm and the fast LMS algorithm to solve a real-life filtering problem was carried out. In short, in this paper the piezoresistive accelerometer was tested for a multi-frequency acceleration excitation. Due to the kind of test conducted in this paper, the use of conventional filtering was discarded and the choice of one adaptive filter over the other was based on the signal-to-noise ratio improvement and the convergence rate.
DEFF Research Database (Denmark)
Nielson, Hanne Riis; Nielson, Flemming
2009-01-01
The calculus of communicating systems, CCS, was introduced by Robin Milner as a calculus for modelling concurrent systems. Subsequently several techniques have been developed for analysing such models in order to get further insight into their dynamic behaviour. In this paper we present a static...... analysis for approximating the control structure embedded within the models. We formulate the analysis as an instance of a monotone framework and thus draw on techniques that often are associated with the efficient implementation of classical imperative programming languages. We show how to construct...
Improved particle size estimation in digital holography via sign matched filtering.
Lu, Jiang; Shaw, Raymond A; Yang, Weidong
2012-06-04
A matched filter method is provided for obtaining improved particle size estimates from digital in-line holograms. This improvement is relative to conventional reconstruction and pixel counting methods for particle size estimation, which is greatly limited by the CCD camera pixel size. The proposed method is based on iterative application of a sign matched filter in the Fourier domain, with sign meaning the matched filter takes values of ±1 depending on the sign of the angular spectrum of the particle aperture function. Using simulated data the method is demonstrated to work for particle diameters several times the pixel size. Holograms of piezoelectrically generated water droplets taken in the laboratory show greatly improved particle size measurements. The method is robust to additive noise and can be applied to real holograms over a wide range of matched-filter particle sizes.
PERFORMANCE IMPROVEMENT FOR PAPR REDUCTION IN LTE DOWNLINK SYSTEM WITH ELLIPTIC FILTERING
Directory of Open Access Journals (Sweden)
Snikdho Sworov Haque
2015-01-01
Full Text Available This paper is concerned with the performance improvement of PAPR reduction of orthogonal frequency division multiplexing (OFDM signal using amplitude clipping & filtering based design. Note that OFDM is one of the well adept multi-carrier multiplexing transmission scheme which has been implemented in long term evolution (LTE downlink. Nonetheless peak to average power ratio (PAPR is the more rattling problem with OFDM, consequently in this paper a reduction procedure of the PAPR by using amplitude clipping and filtering is proposed. Here we used IIR bandpass elliptic filter after amplitude clipping to reduce the PAPR. The performance of the system in terms of bit error rate (BER is also canvased as a new filter based clipping method. Our results show that the proposed methodology of clipping method with the IIR elliptic band pass filter significantly reduces the PAPR value.
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.
Improvement for Speech Signal based on Post Wiener Filter and Adjustable Beam-Former
Directory of Open Access Journals (Sweden)
Xiaorong Tong
2013-06-01
Full Text Available In this study, a two-stage filter structure is introduced for speech enhancement. The first stage is an adjustable filter and sum beam-former with four-microphone array. The control of beam-forming filter is realized by adjusting only a single control variable. Different from the adaptive beam-forming filter, the proposed filter structure does not bring to any adaptive error noise, thus, it also does not bring the trouble to the second stage of the speech signal processing. The second stage of the proposed filter is a Wiener filter. The estimation of signal’s power spectrum for Wiener filter is realized by cross-correlation between primary outputs of two adjacent directional beams. This estimation is based on the assumption that the noise outputs of the two adjacent directional beams come from two independent noise source but the speech outputs come from the same speech source. The simulation results shown that the proposed algorithm can improve the Signal-Noise-Ratio (SNR about 6 dB.
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.
An improved particle filtering algorithm for aircraft engine gas-path fault diagnosis
Directory of Open Access Journals (Sweden)
Qihang Wang
2016-07-01
Full Text Available In this article, an improved particle filter with electromagnetism-like mechanism algorithm is proposed for aircraft engine gas-path component abrupt fault diagnosis. In order to avoid the particle degeneracy and sample impoverishment of normal particle filter, the electromagnetism-like mechanism optimization algorithm is introduced into resampling procedure, which adjusts the position of the particles through simulating attraction–repulsion mechanism between charged particles of the electromagnetism theory. The improved particle filter can solve the particle degradation problem and ensure the diversity of the particle set. Meanwhile, it enhances the ability of tracking abrupt fault due to considering the latest measurement information. Comparison of the proposed method with three different filter algorithms is carried out on a univariate nonstationary growth model. Simulations on a turbofan engine model indicate that compared to the normal particle filter, the improved particle filter can ensure the completion of the fault diagnosis within less sampling period and the root mean square error of parameters estimation is reduced.
Improvement of spatial resolution in confocal microscope with shifted-focus phase filter
Huang, Xiangdong; Xiang, Xiaoyan; Wang, Chongyang
2015-02-01
A spatial super-resolution method is proposed based on the multiplicative character of confocal microscope's amplitude point-spread functions. The axial resolution can be greatly improved by introducing a shifted-focus phase filters in illumination part of a confocal microscope. However, this improvement is accompanied by a decrease of transversal resolution. Thus, a super-Gaussian phase filter is optimized to control the focal shift and transversal intensity distribution in a confocal microscope. Numerical simulation results indicate that the proposed method is useful to obtain a significant improvement in the optical sectioning capacity.
On the sample monotonization problem
Takhanov, R. S.
2010-07-01
The problem of finding a maximal subsample in a training sample consisting of the pairs “object-answer” that does not violate monotonicity constraints is considered. It is proved that this problem is NP-hard and that it is equivalent to the problem of finding a maximum independent set in special directed graphs. Practically important cases in which a partial order specified on the set of answers is a complete order or has dimension two are considered in detail. It is shown that the second case is reduced to the maximization of a quadratic convex function on a convex set. For this case, an approximate polynomial algorithm based on linear programming theory is proposed.
Directory of Open Access Journals (Sweden)
Bijan Rahmani
2016-08-01
Full Text Available Available photovoltaic (PV systems show a prolonged transient response, when integrated into the power grid via active filters. On one hand, the conventional low-pass filter, employed within the integrated PV system, works with a large delay, particularly in the presence of system’s low-order harmonics. On the other hand, the switching of the DC (direct current–DC converters within PV units also prolongs the transient response of an integrated system, injecting harmonics and distortion through the PV-end current. This paper initially develops a wavelet-based low-pass filter to improve the transient response of the interconnected PV systems to grid lines. Further, a damped input filter is proposed within the PV system to address the raised converter’s switching issue. Finally, Matlab/Simulink simulations validate the effectiveness of the proposed wavelet-based low-pass filter and damped input filter within an integrated PV system.
The development of a HEPA filter with improved dust holding characteristics
Energy Technology Data Exchange (ETDEWEB)
Dyment, J.; Hamblin, C.
1995-02-01
A limitation of the HEPA filters used in the extract of nuclear facilities is their relatively low capacity for captured dust. The costs associated with the disposal of a typical filter means that there are clear incentives to extend filter life. The work described in this report are the initial stages in the development of a filter which incorporates a medium which enhances its dust holding capacity. Experimental equipment was installed to enable the dust loading characteristics of candidate media to be compared with those of the glass fibre based papers currently used in filter construction. These tests involved challenging representative samples of the media with an air stream containing a controlled concentration of thermally generated sodium chloride particles. The dust loading characteristics of the media were then compared in terms of the rate of increasing in pressure differential. A number of {open_quotes}graded density{close_quotes} papers were subsequently identified which appeared to offer significant improvements in dust holding. In the second phase of the programme deep-pleat filters (1,700 M{sup 3}h{sup {minus}1}) incorporating graded density papers were manufactured and tested. Improvements of up to 50% were observed in their capacity for the sub-micron sodium chloride test dust. Smaller differences (15%) were measured when a coarser, carbon black, challenge was used. This is attributed to the differences in the particles sizes of the two dusts.
A stepped-impedance bandstop filter with extended upper passbands and improved pass-band reflections
Zuo, Xiaoying; Yu, Jianguo
2016-09-01
A high-performance planar bandstop filter with extended upper passbands and improved pass-band return loss is proposed in this article. In this proposed bandstop filter, a novel three-section stepped-impedance structure is suggested to improve the pass-band reflections without affecting the desired band-stop and extended upper passband performances. The analysis and design considerations of this filter are provided while the proposed design approach is verified by full-wave simulation, microstrip implementation and accurate measurement of a typical fabricated filter operating at 1 GHz(fo). Compared to the conventional one, the proposed bandstop filter has main and obvious advantages of simple single-layer structure, perfect band-stop filtering performance (Suppression of better than 20 dB), excellent low/high pass-band return loss (Reflection of lower than -17 dB) in the extended upper passbands(Larger than 5.96 fo), and flat group-delay transmission (Variations of smaller than 0.22 ns).
A stepped-impedance bandstop filter with extended upper passbands and improved pass-band reflections
Directory of Open Access Journals (Sweden)
Xiaoying Zuo
2016-09-01
Full Text Available A high-performance planar bandstop filter with extended upper passbands and improved pass-band return loss is proposed in this article. In this proposed bandstop filter, a novel three-section stepped-impedance structure is suggested to improve the pass-band reflections without affecting the desired band-stop and extended upper passband performances. The analysis and design considerations of this filter are provided while the proposed design approach is verified by full-wave simulation, microstrip implementation and accurate measurement of a typical fabricated filter operating at 1 GHz(fo. Compared to the conventional one, the proposed bandstop filter has main and obvious advantages of simple single-layer structure, perfect band-stop filtering performance (Suppression of better than 20 dB, excellent low/high pass-band return loss (Reflection of lower than -17 dB in the extended upper passbands(Larger than 5.96 fo, and flat group-delay transmission (Variations of smaller than 0.22 ns.
Improving the Prediction Accuracy of Multicriteria Collaborative Filtering by Combination Algorithms
Directory of Open Access Journals (Sweden)
Wiranto
2014-05-01
Full Text Available This study focuses on developing the multicriteria collaborative filtering algorithmfor improving the prediction accuracy. The approaches applied were user-item multirating matrix decomposition, the measurement of user similarity using cosine formula and multidimensional distance, individual criteria weight calculation, and rating prediction for the overall criteria by a combination approach. Results of the study show variation in multicriteria collaborative filtering algorithm, which was used for improving the document recommender system with the two following characteristics. First, the rating prediction for four individual criteria using collaborative filtering algorithm by a cosine-based user similarity and a multidimensional distance-based user similarity. Second, the rating prediction for the overall criteria using a combination algorithms. Based on the results of testing, it can be concluded that a variety of models developed for the multicriteria collaborative filtering systems had much better prediction accuracy than for the classic collaborative filtering, which was characterized by the increasingly smaller values of Mean Absolute Error. The best accuracy was achieved by the multicriteria collaborative filtering system with multidimensional distance-based similarity.
GPS/UWB/MEMS-IMU tightly coupled navigation with improved robust Kalman filter
Li, Zengke; Chang, Guobin; Gao, Jingxiang; Wang, Jian; Hernandez, Alberto
2016-12-01
The integration of Global Positioning System (GPS) with Inertial Navigation System (INS) has been very intensively developed and widely applied in multiple areas. To further enhance the reliability and availability of GPS/INS integrated navigation in GPS challenging environment, range observation through ultra-wideband (UWB) is introduced in GPS/INS tightly coupled navigation. An improved robust Kalman filter is proposed and used to resist the influence of gross error from UWB observation in GPS/UWB/IMU tightly coupled navigation. The variance of the squared Mahalanobis distance in moving window is calculated, which brings as new judgement factor for gross errors in order to decrease the rate of false outlier identification. A simulation analysis shows that the improved robust Kalman filter is able to correctly identify gross errors and the rate of false judgment as zero. In order to validate the new robust filter, a real experiment is conducted. The results indicate that the improved robust Kalman filter used in GPS/UWB/INS tightly coupled navigation is able to remove the harmful effect of gross error in UWB observation. It clearly illustrates that the improved robust Kalman filter is very effective, and all the simulated small and large gross errors added to UWB distance observation are successfully identified.
Mobile robot simultaneous localization and map building based on improved particle filter
Institute of Scientific and Technical Information of China (English)
Li Maohai; Hong Bingrong; Wei Zhenhua
2006-01-01
We present an investigation into the use of pan tilt zoom camera and sonar sensors for simultaneous localization and mapping with artificial colored landmarks. An improved particle filter is applied to estimate a posterior of the pose of the robot, in which each particle has associated it with an entire map. The distributions of landmarks are also represented by particle sets, where separate particles are used to represent the robot and the landmarks. Hough transform is used to extract line segments from sonar observations and build map simultaneously. The key advantage of our method is that the full posterior over robot poses and landmarks can be nonlinearly approximated at every point in time by particles. Especially the landmarks are affixed on the moving robots, which can reduce the impact of the depletion problem and the impoverishment problem produced by basic particle filter. Experimental results show that this approach has advantages over the basic particle filter and the extended Kalman filter.
A 6-pole filter for improving the readability of muscle contaminated EEGs.
Ives, J R; Schomer, D L
1988-05-01
A multi-channel switched-capacitor 6-pole filter for significantly reducing the EMG artifact present during seizures recorded by long-term monitoring procedures has been implemented for routine use. This permits repeated replay of the seizures with different filter settings. All of the channels can be simultaneously dialed to any cut-off frequency (3 dB down) between 8 Hz and 70 Hz and the event replayed for filtering and write-out onto any standard EEG machine. The advantage of the 6-pole switched-capacitor filter is that it does not require a complex design with high precision RC components. The cut-off frequency is determined by the frequency of a simple clock that is used to select the same cut-off point for all 16 channels. By changing the clock frequency, the operator moves the cut-off point linearly. The dramatic improvement obtained by off-line digital filtering that was recently reported (Gotman et al. 1981) indicates that more efficient filtering of EMG contaminated seizures is diagnostically significant in selected cases. This approach is limited by the availability and expense of not only the computer's hardware but also the dedicated software. Specially designed 4-pole analog filters (Barlow 1984) are less expensive than digital filtering, but are difficult to design even at specific frequencies and do not allow for a range of frequencies. The switched-capacitor 6-pole filters have all the advantages of the above but are even more efficient in reducing EMG artifact. They also do not have any of the above disadvantages and cost only a few dollars per channel.
Development of Improved Iron-Aluminide Filter Tubes and Elements
Energy Technology Data Exchange (ETDEWEB)
Judkins, R.R.; Sutton, T.G.; Miller, C.J.; Tortorelli, P.F.
2008-01-14
The purpose of this Cooperative Research and Development Agreement (CRADA) was to explore and develop advanced manufacturing techniques to fabricate sintered iron-aluminide intermetallic porous bodies used for gas filtration so as to reduce production costs while maintaining or improving performance in advanced coal gasification and combustion systems. The use of a power turbine fired with coal-derived synthesis gas requires some form of gas cleaning in order to protect turbine and downstream components from degradation by erosion, corrosion, and/or deposition. Hot-gas filtration is one form of cleaning that offers the ability to remove particles from the gases produced by gasification processes without having to substantially cool and, possibly, reheat them before their introduction into the turbine. This technology depends critically on materials durability and reliability, which have been the subject of study for a number of years.
Side-effects of improving CERN's spam filter
2004-01-01
To further improve the fight against spam (unsolicited email), CERN implemented in June a mechanism that returns electronic mail messages to the sender if the originating server is wrongly configured. This "reverse DNS lookup" is an increasingly widespread technique to identify whether the sending e-mail server is legitimate and has a valid host name. This change has nearly doubled the spam rejection efficiency at CERN. However, it has a known side-effect. A small number of correspondents are sending legitimate electronic mail to CERN from mail servers that are incorrectly configured (in technical terms, they do not have a reverse DNS registration). These persons will have their messages returned to them with an error message, provided their sender address is valid. The typical error message that the correspondent receives in such cases is "Relaying denied. No reverse DNS configured for IP". If a correspondent complains to you that emails they are sending you at CERN are being returned with...
Hara, Yousuke; Takada, Yoshihisa; Hotta, Kenji; Tansho, Ryohei; Nihei, Tetsuya; Suzuki, Yojiro; Nagafuchi, Kosuke; Kawai, Ryuichi; Tanabe, Masaki; Mizutani, Shohei; Himukai, Takeshi; Matsufuji, Naruhiro
2012-03-21
We have developed a novel design method of ridge filters for carbon-ion therapy using a broad-beam delivery system to improve the flatness of a biologically effective dose in the spread-out Bragg peak (SOBP). So far, the flatness of the SOBP is limited to about ±5% for carbon beams since the weight control of component Bragg curves composing the SOBP is difficult. This difficulty arises from using a large number of ridge-bar steps (e.g. about 100 for a SOBP width of 60 mm) required to form the SOBP for the pristine Bragg curve with an extremely sharp distal falloff. Instead of using a single ridge filter, we introduce a ripple filter to broaden the Bragg peak so that the number of ridge-bar steps can be reduced to about 30 for SOBP with of 60 mm for the ridge filter designed for the broadened Bragg peak. Thus we can manufacture the ridge filter more accurately and then attain a better flatness of the SOBP due to well-controlled weights of the component Bragg curves. We placed the ripple filter on the same frame of the ridge filter and arranged the direction of the ripple-filter-bar array perpendicular to that of the ridge-filter-bar array. We applied this method to a 290 MeV u(-1) carbon-ion beam in Heavy Ion Medical Accelerator in Chiba and verified the effectiveness by measurements.
Mehryar, Esmaeil; Bi, Jinhua
2016-01-01
To enhance the codigestion of degradation and improve biomethane production potential, sugarcane bagasse and filter mud were pretreated by sodium hydroxide NaOH 1 N at 100°C for 15, 30, and 45 minutes, respectively. Biomethane generation from 1-liter batch reactor was studied at mesophilic temperature (37 ± 1)°C, solid concentrations of 6%, and five levels of mixing proportion with and without pretreatment. The results demonstrate that codigestion of filter mud with bagasse produces more biomethane than fermentation of filter mud as single substrate; even codigested substrate composition presented a better balance of nutrients (C/N ratio of 24.70) when codigestion ratio between filter mud and bagasse was 25 : 75 in comparison to filter mud as single substrate (C/N ratio 9.68). All the pretreatments tested led to solubilization of the organic matter, with a maximum lignin reduction of 86.27% and cumulative yield of biomethane (195.8 mL·gVS−1, digestion of pretreated bagasse as single substrate) obtained after 45 minutes of cooking by NaOH 1 N at 100°C. Under this pretreatment condition, significant increase in cumulative methane yield was observed (126.2 mL·gVS−1) at codigestion ratio of 25 : 75 between filter mud and bagasse by increase of 81.20% from untreated composition.
Accounting for filter bandwidth improves the quantitative accuracy of bioluminescence tomography
Taylor, Shelley L.; Mason, Suzannah K. G.; Glinton, Sophie L.; Cobbold, Mark; Dehghani, Hamid
2015-09-01
Bioluminescence imaging is a noninvasive technique whereby surface weighted images of luminescent probes within animals are used to characterize cell count and function. Traditionally, data are collected over the entire emission spectrum of the source using no filters and are used to evaluate cell count/function over the entire spectrum. Alternatively, multispectral data over several wavelengths can be incorporated to perform tomographic reconstruction of source location and intensity. However, bandpass filters used for multispectral data acquisition have a specific bandwidth, which is ignored in the reconstruction. In this work, ignoring the bandwidth is shown to introduce a dependence of the recovered source intensity on the bandwidth of the filters. A method of accounting for the bandwidth of filters used during multispectral data acquisition is presented and its efficacy in increasing the quantitative accuracy of bioluminescence tomography is demonstrated through simulation and experiment. It is demonstrated that while using filters with a large bandwidth can dramatically decrease the data acquisition time, if not accounted for, errors of up to 200% in quantitative accuracy are introduced in two-dimensional planar imaging, even after normalization. For tomographic imaging, the use of this method to account for filter bandwidth dramatically improves the quantitative accuracy.
An Improved Variable Structure Adaptive Filter Design and Analysis for Acoustic Echo Cancellation
Directory of Open Access Journals (Sweden)
A. Kar
2015-04-01
Full Text Available In this research an advance variable structure adaptive Multiple Sub-Filters (MSF based algorithm for single channel Acoustic Echo Cancellation (AEC is proposed and analyzed. This work suggests a new and improved direction to find the optimum tap-length of adaptive filter employed for AEC. The structure adaptation, supported by a tap-length based weight update approach helps the designed echo canceller to maintain a trade-off between the Mean Square Error (MSE and time taken to attain the steady state MSE. The work done in this paper focuses on replacing the fixed length sub-filters in existing MSF based AEC algorithms which brings refinements in terms of convergence, steady state error and tracking over the single long filter, different error and common error algorithms. A dynamic structure selective coefficient update approach to reduce the structural and computational cost of adaptive design is discussed in context with the proposed algorithm. Simulated results reveal a comparative performance analysis over proposed variable structure multiple sub-filters designs and existing fixed tap-length sub-filters based acoustic echo cancellers.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Y.; Draelants, D.J.; Engelen, K.; Baron, G.V.
2002-09-19
This work focuses on the development of catalytic candle filters for the simultaneous removal of tars and particles from the biomass gasification gas at high temperature. An improvement of sulphur resistance of the nickel-activated catalytic filter was developed by the addition of CaO. The influences of preparation procedure of catalytic filter, the ratio of Ni/CaO and the loading of Ni and CaO on the performance of the catalytic filter were investigated.
Improvement of nonlinear diffusion equation using relaxed geometric mean filter for low PSNR images
DEFF Research Database (Denmark)
Nadernejad, Ehsan
2013-01-01
A new method to improve the performance of low PSNR image denoising is presented. The proposed scheme estimates edge gradient from an image that is regularised with a relaxed geometric mean filter. The proposed method consists of two stages; the first stage consists of a second order nonlinear...... anisotropic diffusion equation with new neighboring structure and the second is a relaxed geometric mean filter, which processes the output of nonlinear anisotropic diffusion equation. The proposed algorithm enjoys the benefit of both nonlinear PDE and relaxed geometric mean filter. In addition, the algorithm...... will not introduce any artefacts, and preserves image details, sharp corners, curved structures and thin lines. Comparison of the results obtained by the proposed method, with those of other methods, shows that a noticeable improvement in the quality of the denoised images, that were evaluated subjectively...
An improved MTI filter for ground clutter reduction in UAV classification
Wan, Fangyuan; Liu, Qinglai; Wang, Chen; Guo, Xin; Lin, Zhiping
2017-06-01
In recent years, Unmanned Aerial Vehicles (UAVs) have increasingly been used in many civil applications. However, they also pose a significant threat in restricted zones. Radar can be used to detect and discriminate UAVs. Due to the low flying altitude of the UAVs, it is found that the radar signals also include some unwanted echoes, reflected by building, ground, trees and grasses etc. Consequently, it has not been possible to get the clean UAVs characteristics for further classification. In this paper, the MTI filter is applied to cancel the ground clutter and based this, an improved MTI filter is further proposed. Compared with the traditional MTI filter, the improved one significantly enhances ground clutter rejection capability while maintaining most of the target power. As the result, the cleaner UAVs classification characteristics can be obtained. The effectiveness of the proposed method has been verified by an experimental CW radar dataset, collected from a helicopter UAV.
Improved detection of coliforms and Escherichia coli in foods by a membrane filter method.
Sharpe, A N; Peterkin, P I; Malik, N
1979-09-01
Analytical procedures based on filtration of homogenates through membrane filters, and particularly hydrophobic grid-membrane filters (HGMF), offer definite improvements in the enumeration of Escherichia coli and coliforms in foods. Whereas the counted specimen in pour plates may not usually be greater than 0.1 g, up to 1.0 g of ground beef, green beans, potato, cod, strawberries, or grapes could be filtered and counted on HGMF. Greatly improved limit of detection, reduced interference by noncoliforms, and complete removal of growth inhibitors such as polyphenols were demonstrated for HGMF, using violet red bile and mFC agars. In addition, counting on HGMF eliminated a false-positive reaction caused by sucrose in ice cream.
Monotonic Allocation Schemes in Clan Games
Voorneveld, M.; Tijs, S.H.; Grahn, S.
2000-01-01
Total clan games are characterized using monotonicity, veto power of the clan members, and a concavity condition reflecting the decreasing marginal contribution of non-clan members to growing coalitions.This decreasing marginal contribution is incorporated in the notion of a bi-monotonic allocation
Monotone models for prediction in data mining
Velikova, M.V.
2006-01-01
This dissertation studies the incorporation of monotonicity constraints as a type of domain knowledge into a data mining process. Monotonicity constraints are enforced at two stages¿data preparation and data modeling. The main contributions of the research are a novel procedure to test the degree of
Monotonic Stable Solutions for Minimum Coloring Games
Hamers, H.J.M.; Miquel, S.; Norde, H.W.
2011-01-01
For the class of minimum coloring games (introduced by Deng et al. (1999)) we investigate the existence of population monotonic allocation schemes (introduced by Sprumont (1990)). We show that a minimum coloring game on a graph G has a population monotonic allocation scheme if and only if G is (P4,
Monotonicity-preserving linear multistep methods
Hundsdorfer, W.; Ruuth, S.J.; Spiteri, R.J.
2002-01-01
In this paper we provide an analysis of monotonicity properties for linear multistep methods. These monotonicity properties include positivity and the diminishing of total variation. We also pay particular attention to related boundedness properties such as the total-variation-bounded (TVB) property
Version Spaces and Generalized Monotone Boolean Functions
J.C. Bioch (Cor); T. Ibaraki
2002-01-01
textabstractWe consider generalized monotone functions f: X --> {0,1} defined for an arbitrary binary relation <= on X by the property x <= y implies f(x) <= f(y). These include the standard monotone (or positive) Boolean functions, regular Boolean functions and other interesting functions as speci
Version Spaces and Generalized Monotone Boolean Functions
J.C. Bioch (Cor); T. Ibaraki
2002-01-01
textabstractWe consider generalized monotone functions f: X --> {0,1} defined for an arbitrary binary relation <= on X by the property x <= y implies f(x) <= f(y). These include the standard monotone (or positive) Boolean functions, regular Boolean functions and other interesting functions as
Monotone Hurwitz numbers in genus zero
Goulden, I P; Novak, Jonathan
2012-01-01
Hurwitz numbers count branched covers of the Riemann sphere with specified ramification data, or equivalently, transitive permutation factorizations in the symmetric group with specified cycle types. Monotone Hurwitz numbers count a restricted subset of the branched covers counted by the Hurwitz numbers, and have arisen in recent work on the the asymptotic expansion of the Harish-Chandra-Itzykson-Zuber integral. In this paper we begin a detailed study of monotone Hurwitz numbers. We prove two results that are reminiscent of those for classical Hurwitz numbers. The first is the monotone join-cut equation, a partial differential equation with initial conditions that characterizes the generating function for monotone Hurwitz numbers in arbitrary genus. The second is our main result, in which we give an explicit formula for monotone Hurwitz numbers in genus zero.
Distributed mode filtering rod fiber amplifier delivering 292W with improved mode stability
DEFF Research Database (Denmark)
Laurila, Marko; Jørgensen, Mette Marie; Hansen, Kristian Rymann
2012-01-01
We demonstrate a high power fiber (85μm core) amplifier delivering up to 292Watts of average output power using a mode-locked 30ps source at 1032nm. Utilizing a single mode distributed mode filter bandgap rod fiber, we demonstrate 44% power improvement before the threshold-like onset of mode...
Improving Efficiency of a Counter-Current Flow Moving Bed Granular Filter
Energy Technology Data Exchange (ETDEWEB)
Colver, G.M.; Brown, R.C.; Shi, H.; Soo, D.S-C.
2002-09-18
The goal of this research is to improve the performance of moving bed granular filters for gas cleaning at high temperatures and pressures. A second goal of the research is to optimize the performances of both solids and gas filtering processes through appropriate use of granular bed materials, particle sizes, feed rates etc. in a factorial study. These goals are directed toward applications of advanced coal-fired power cycles under development by the U.S. Department of Energy including pressurized fluidized bed combustion and integrated gasification/combined cycles based on gas turbines and fuel cells. Only results for particulate gas cleaning are reported here.
A reconfigurable complex band-pass filter with improved passive compensation
Institute of Scientific and Technical Information of China (English)
Fan Chaojie; Mo Tingting; Chen Dongpo; Zhou Jianjun
2012-01-01
This paper presents a 5th-order Chebyshev-Ⅰ active RC complex filter for multi-mode multi-band global navigation satellite systems (GNSS) RF receivers.An improved passive compensation technique is used to cancel the excess phase lag of the integrators,thus ensuring the in-band flatness of the frequency response over various ambient conditions.The filter has a programmable gain from 0 to 42 dB with a 6 dB step,a tunable center frequency at either 6.4 MHz or 16 MHz,and a bandwidth from 2 to 20 MHz with less than 3％ frequency uncertainty.Implemented in a 0.18 μm CMOS process,the whole filter consumes 7.8 mA from a 1.8 V supply voltage and occupies a die area of 0.4 mm2.
A hand tracking algorithm with particle filter and improved GVF snake model
Sun, Yi-qi; Wu, Ai-guo; Dong, Na; Shao, Yi-zhe
2017-07-01
To solve the problem that the accurate information of hand cannot be obtained by particle filter, a hand tracking algorithm based on particle filter combined with skin-color adaptive gradient vector flow (GVF) snake model is proposed. Adaptive GVF and skin color adaptive external guidance force are introduced to the traditional GVF snake model, guiding the curve to quickly converge to the deep concave region of hand contour and obtaining the complex hand contour accurately. This algorithm realizes a real-time correction of the particle filter parameters, avoiding the particle drift phenomenon. Experimental results show that the proposed algorithm can reduce the root mean square error of the hand tracking by 53%, and improve the accuracy of hand tracking in the case of complex and moving background, even with a large range of occlusion.
Hayes, Charles E.; McClellan, James H.; Scott, Waymond R.; Kerr, Andrew J.
2016-05-01
This work introduces two advances in wide-band electromagnetic induction (EMI) processing: a novel adaptive matched filter (AMF) and matched subspace detection methods. Both advances make use of recent work with a subspace SVD approach to separating the signal, soil, and noise subspaces of the frequency measurements The proposed AMF provides a direct approach to removing the EMI self-response while improving the signal to noise ratio of the data. Unlike previous EMI adaptive downtrack filters, this new filter will not erroneously optimize the EMI soil response instead of the EMI target response because these two responses are projected into separate frequency subspaces. The EMI detection methods in this work elaborate on how the signal and noise subspaces in the frequency measurements are ideal for creating the matched subspace detection (MSD) and constant false alarm rate matched subspace detection (CFAR) metrics developed by Scharf The CFAR detection metric has been shown to be the uniformly most powerful invariant detector.
Development of a mixed pixel filter for improved dimension estimation using AMCW laser scanner
Wang, Qian; Sohn, Hoon; Cheng, Jack C. P.
2016-09-01
Accurate dimension estimation is desired in many fields, but the traditional dimension estimation methods are time-consuming and labor-intensive. In the recent decades, 3D laser scanners have become popular for dimension estimation due to their high measurement speed and accuracy. Nonetheless, scan data obtained by amplitude-modulated continuous-wave (AMCW) laser scanners suffer from erroneous data called mixed pixels, which can influence the accuracy of dimension estimation. This study develops a mixed pixel filter for improved dimension estimation using AMCW laser scanners. The distance measurement of mixed pixels is firstly formulated based on the working principle of laser scanners. Then, a mixed pixel filter that can minimize the classification errors between valid points and mixed pixels is developed. Validation experiments were conducted to verify the formulation of the distance measurement of mixed pixels and to examine the performance of the proposed mixed pixel filter. Experimental results show that, for a specimen with dimensions of 840 mm × 300 mm, the overall errors of the dimensions estimated after applying the proposed filter are 1.9 mm and 1.0 mm for two different scanning resolutions, respectively. These errors are much smaller than the errors (4.8 mm and 3.5 mm) obtained by the scanner's built-in filter.
Hara, Takanori; Ichikawa, Katsuhiro; Tsuzaka, Masatoshi
2005-07-20
In this study, we processed reconstructed images with a new image filter (Siemens Medical Systems, Adaptive Image Filter: AIF). As one of its characteristics, the filter uses low-pass filtering. When an image that emphasizes a high-frequency element is changed to one with a reduced high-frequency element, an image suitable for clinical use can be obtained. For the resolving characteristic and the noise characteristic, we evaluated the degree of transition, using the modulation transfer factor (MTF) and Wiener spectrum (WS). Moreover, we used the signal-to-noise ratio (SNR) to examine the total loss of signal detection capability after use of the AIF. The results showed that, when we changed to images using the AIF and made it the same level as B30 and U40, we had to hold down the kernel level to at least B60 and U80. The use of an image filter did not recognize less of an SNR in comparison with the reconstruction image. In this study, changes in detailed characteristics of the image and SNR could be evaluated objectively using the AIF. As for the effective method by AIF that raw data isn't used for is available for the control of an image (times) using reconstruction and the change of an image on database. Therefore, we consider the AIF useful to improve workflow in CT examinations.
Research on Improved Collaborative Filtering Recommendation Algorithm on MapReduce
Directory of Open Access Journals (Sweden)
Dong Jie
2016-01-01
Full Text Available Information overload is one of the most serious problems in big data environment, recommendation systems is a way to effectively mitigate the problem. In order to make use of rich user feedback and social networks information and to further improve the performance of the recommendation system ,This thesis makes a improvement on the user-based collaborative filtering algorithm by normalization method, Meanwhile the algorithm could be run on the MapReduce in the Hadoop platform. The experimental results show that the algorithm on Hadoop platform can effectively improve the accuracy of the data to recommend and computational efficiency, so as to improve the satisfaction of users.
Criteria for Response Monotonicity Preserving in Approximation of Fractional Order Systems
Institute of Scientific and Technical Information of China (English)
Mohammad Saleh Tavazoei
2016-01-01
In approximation of fractional order systems,a significant objective is to preserve the important properties of the original system.The monotonicity of time/frequency responses is one of these properties whose preservation is of great importance in approximation process.Considering this importance,the issues of monotonicity preservation of the step response and monotonicity preservation of the magnitude-frequency response are independently investigated in this paper.In these investigations,some conditions on approximating filters of fractional operators are found to guarantee the preservation of step/magnitude-frequency response monotonicity in approximation process.These conditions are also simplified in some special cases.In addition,numerical simulation results are presented to show the usefulness of the obtained conditions.
Viable harvest of monotone bioeconomic models
De Lara, Michel; Cabrera, Hector Ramirez
2009-01-01
Some monospecies age class models, as well as specific multi-species models (with so-called technical interactions), exhibit useful monotonicity properties. This paper deals with discrete time monotone bioeconomics dynamics in the presence of state and control constraints. In practice, these latter ``acceptable configurations'' represent production and preservation requirements to be satisfied for all time, and they also possess monotonicity properties. A state $\\state$ is said to belong to the viability kernel if there exists a trajectory, of states and controls, starting from $\\state$ and satisfying the constraints. Under monotonicity assumptions, we present upper and lower estimates of the viability kernel. This helps delineating domains where a viable management is possible. Numerical examples, in the context of fisheries management, for the Chilean sea bass (\\emph{Dissostichus eleginoides}) and Alfonsino (\\emph{Beryx splendens}) are given.
Hyperbolic monotonicity in the Hilbert ball
Directory of Open Access Journals (Sweden)
Reich Simeon
2006-01-01
Full Text Available We first characterize -monotone mappings on the Hilbert ball by using their resolvents and then study the asymptotic behavior of compositions and convex combinations of these resolvents.
Modeling,Analysis and Simulation ofThree Phase Hybrid Power Filter forPower Quality Improvement
Directory of Open Access Journals (Sweden)
Prashanta Kumar Das
2012-05-01
Full Text Available A three-phase hybrid series power filter is constituted by a series active filter and a passive filter connected in parallel with the load. The control strategy is based on the “dual formulation of the electric power vectorial theory”. The proposed algorithm eliminates the current harmonics of supply. It also improves the power factor and harmonic compensation features of the associated passive filter even if there is a change in system parameters.A shunt hybrid power filter is constituted by a shunt active filter and a passive filter connected in parallel with the load, is proposed with same control strategy. Simulations have been carried out on the MATLAB-SIMULINK platform with different loads and with variation in the source impedance.
Multi-Sensor Fusion with Interacting Multiple Model Filter for Improved Aircraft Position Accuracy
Directory of Open Access Journals (Sweden)
Changho Lee
2013-03-01
Full Text Available The International Civil Aviation Organization (ICAO has decided to adopt Communications, Navigation, and Surveillance/Air Traffic Management (CNS/ATM as the 21st century standard for navigation. Accordingly, ICAO members have provided an impetus to develop related technology and build sufficient infrastructure. For aviation surveillance with CNS/ATM, Ground-Based Augmentation System (GBAS, Automatic Dependent Surveillance-Broadcast (ADS-B, multilateration (MLAT and wide-area multilateration (WAM systems are being established. These sensors can track aircraft positions more accurately than existing radar and can compensate for the blind spots in aircraft surveillance. In this paper, we applied a novel sensor fusion method with Interacting Multiple Model (IMM filter to GBAS, ADS-B, MLAT, and WAM data in order to improve the reliability of the aircraft position. Results of performance analysis show that the position accuracy is improved by the proposed sensor fusion method with the IMM filter.
Characterisation and improvement of j(O1D) filter radiometers
Bohn, Birger; Heard, Dwayne E.; Mihalopoulos, Nikolaos; Plass-Dülmer, Christian; Schmitt, Rainer; Whalley, Lisa K.
2016-07-01
Atmospheric O3 → O(1D) photolysis frequencies j(O1D) are crucial parameters for atmospheric photochemistry because of their importance for primary OH formation. Filter radiometers have been used for many years for in situ field measurements of j(O1D). Typically the relationship between the output of the instruments and j(O1D) is non-linear because of changes in the shape of the solar spectrum dependent on solar zenith angles and total ozone columns. These non-linearities can be compensated for by a correction method based on laboratory measurements of the spectral sensitivity of the filter radiometer and simulated solar actinic flux density spectra. Although this correction is routinely applied, the results of a previous field comparison study of several filter radiometers revealed that some corrections were inadequate. In this work the spectral characterisations of seven instruments were revised, and the correction procedures were updated and harmonised considering recent recommendations of absorption cross sections and quantum yields of the photolysis process O3 → O(1D). Previous inconsistencies were largely removed using these procedures. In addition, optical interference filters were replaced to improve the spectral properties of the instruments. Successive determinations of spectral sensitivities and field comparisons of the modified instruments with a spectroradiometer reference confirmed the improved performance. Overall, filter radiometers remain a low-maintenance alternative of spectroradiometers for accurate measurements of j(O1D) provided their spectral properties are known and potential drifts in sensitivities are monitored by regular calibrations with standard lamps or reference instruments.
Development of improved low-cost ceramic water filters for viral removal in the Haitian context
Guerrero-Latorre, Laura; Rusiñol Arantegui, Marta; Hundesa Gonfa, Ayalkibet; Garcia Vallès, Maite; Martínez Manent,Salvador; Joseph, Osnick; Bofill Mas, Silvia; Gironès Llop, Rosina
2015-01-01
Household-based water treatment (HWT) is increasingly being promoted to improve water quality and, therefore, health status in low-income countries. Ceramic water filters (CWFs) are used in many regions as sustainable HWT and have been proven to meet World Health Organization (WHO) microbiological performance targets for bacterial removal (24 log); however, the described viral removal efficiencies are insufficient to significantly reduce the associated risk of viral infection. With the object...
State Estimation and Forecasting of the Ski-Slope Model Using an Improved Shadowing Filter
Mat Daud, Auni Aslah
In this paper, we present the application of the gradient descent of indeterminism (GDI) shadowing filter to a chaotic system, that is the ski-slope model. The paper focuses on the quality of the estimated states and their usability for forecasting. One main problem is that the existing GDI shadowing filter fails to provide stability to the convergence of the root mean square error and the last point error of the ski-slope model. Furthermore, there are unexpected cases in which the better state estimates give worse forecasts than the worse state estimates. We investigate these unexpected cases in particular and show how the presence of the humps contributes to them. However, the results show that the GDI shadowing filter can successfully be applied to the ski-slope model with only slight modification, that is, by introducing the adaptive step-size to ensure the convergence of indeterminism. We investigate its advantages over fixed step-size and how it can improve the performance of our shadowing filter.
Delay Estimator and Improved Proportionate Multi-Delay Adaptive Filtering Algorithm
Directory of Open Access Journals (Sweden)
E. Verteletskaya
2012-04-01
Full Text Available This paper pertains to speech and acoustic signal processing, and particularly to a determination of echo path delay and operation of echo cancellers. To cancel long echoes, the number of weights in a conventional adaptive filter must be large. The length of the adaptive filter will directly affect both the degree of accuracy and the convergence speed of the adaptation process. We present a new adaptive structure which is capable to deal with multiple dispersive echo paths. An adaptive filter according to the present invention includes means for storing an impulse response in a memory, the impulse response being indicative of the characteristics of a transmission line. It also includes a delay estimator for detecting ranges of samples within the impulse response having relatively large distribution of echo energy. These ranges of samples are being indicative of echoes on the transmission line. An adaptive filter has a plurality of weighted taps, each of the weighted taps having an associated tap weight value. A tap allocation/control circuit establishes the tap weight values in response to said detecting means so that only taps within the regions of relatively large distributions of echo energy are turned on. Thus, the convergence speed and the degree of estimation in the adaptation process can be improved.
Directory of Open Access Journals (Sweden)
I. C. C. Rocha
2009-12-01
Full Text Available Filtration under an ultrasonic field is a technique that is gaining importance in the wastewater treatment research field, not only due to its ability as a cleaning mechanism, but also as a filtration intensifier. The main objective of this research was the study of the influence of ultrasonic waves on the filtration of theoilfield wastewater (known as produced water in order to increase the operation performance and filter medium regenerative effectiveness. A 0.016 m² hollow cylindrical porous ceramic filter was submitted to the filtration of produced water by two mechanisms: conventional filtration under vacuum and filtration under theinfluence of ultrasonic waves. Experiments were carried out using synthetic produced water by analyzing the variables oil and grease content (O&G and total suspended solids (TSS for each filtration run. Backwashing of the filter medium with distilled water was also performed to evaluate the regeneration efficiency. During conventional filtration, permeate flux decreased gradually, becoming stable around 0.06 cm³.cm-2.s-1. Furthermore, in the filtration assisted by ultrasound, the permeate flux was around 0.15 cm³.cm-2.s-1. Therefore, ultrasonic waves provided an increase of about 150% in the permeate flux. Moreover, the sonication improved filter medium regeneration effectiveness, even under conditions of high TSS and O&G contents. Taking into consideration the very positive results associated with the application of ultrasonicwaves, this filtration technique is likely to become an important industrial process.
Improved Wavelet-based Spatial Filter of Damage Imaging Method on Composite Structures
Institute of Scientific and Technical Information of China (English)
WANG Yu; YUAN Shenfang; QIU Lei
2011-01-01
Piezoelectric sensor array-based spatial filter technology is a new promising method presented in research area of structural health monitoring(SHM)in the recent years.To apply this method to composite structures and give the actual position of damage,this paper proposes a spatial filter-based damage imaging method improved by complex Shannon wavelet transform.The basic principle of spatial filter is analyzed first.Then,this paper proposes a method of using complex Shannon wavelet transform to construct analytic signals of time domain signals of PZT sensors array.The analytic signals are synthesized depending on the principle of the spatial filter to give a damage imaging in the form of angle-time.A method of converting the damage imaging to the form of angle-distance is discussed.Finally,an aircraft composite oil tank is adopted to validate the damage imaging method.The validating results show that this method can recognize angle and distance of damage successfully.
Planar UWB Filter with Multiple Notched Band and Stopband with Improved Rejection Level
Ghazali, Abu Nasar; Pal, Srikanta
2015-05-01
Analysis and realization of a microstrip-based planar ultra-wideband (UWB) filter with integrated multiple notch elimination property and simultaneously extended upper stopband is proposed. Initially, a UWB filter based on back-to-back microstrip-to-CPW technology is designed. Later, multiple spiral defected ground structures (DGS) are embedded to obtain multiple passband notches. Further, double equilateral U (DEU)-type DGS are used to improve upon the rejection level in upper stopband. The multiple passband notches are results of embedded spiral-shaped DGS (SDGS), while extended upper stopband is the outcome of suppressed higher-order spurious harmonics. The flexible dual-attenuation poles of DEU-shaped DGS suppress the stopband harmonics and widen the stopband. An approximate lumped equivalent circuit model of the proposed filter is modelled. The filter is compact and its layout measures 25.26 mm × 11.01 mm. The measured result is in good agreement with the full-wave electromagnetic (EM) simulation and circuit simulation.
Directory of Open Access Journals (Sweden)
Zhenyang Hui
2016-01-01
Full Text Available Filtering is one of the core post-processing steps for airborne LiDAR point cloud. In recent years, the morphology-based filtering algorithms have proven to be a powerful and efficient tool for filtering airborne LiDAR point cloud. However, most traditional morphology-based algorithms have difficulties in preserving abrupt terrain features, especially when using larger filtering windows. In order to suppress the omission error caused by protruding terrain features, this paper proposes an improved morphological algorithm based on multi-level kriging interpolation. This algorithm is essentially a combination of progressive morphological filtering algorithm and multi-level interpolation filtering algorithm. The morphological opening operation is performed with filtering window gradually downsizing, while kriging interpolation is conducted at different levels according to the different filtering windows. This process is iterative in a top to down fashion until the filtering window is no longer greater than the preset minimum filtering window. Fifteen samples provided by the ISPRS commission were chosen to test the performance of the proposed algorithm. Experimental results show that the proposed method can achieve promising results not only in flat urban areas but also in rural areas. Comparing with other eight classical filtering methods, the proposed method obtained the lowest omission error, and preserved protruding terrain features better.
Approximations for Monotone and Non-monotone Submodular Maximization with Knapsack Constraints
Kulik, Ariel; Tamir, Tami
2011-01-01
Submodular maximization generalizes many fundamental problems in discrete optimization, including Max-Cut in directed/undirected graphs, maximum coverage, maximum facility location and marketing over social networks. In this paper we consider the problem of maximizing any submodular function subject to $d$ knapsack constraints, where $d$ is a fixed constant. We establish a strong relation between the discrete problem and its continuous relaxation, obtained through {\\em extension by expectation} of the submodular function. Formally, we show that, for any non-negative submodular function, an $\\alpha$-approximation algorithm for the continuous relaxation implies a randomized $(\\alpha - \\eps)$-approximation algorithm for the discrete problem. We use this relation to improve the best known approximation ratio for the problem to $1/4- \\eps$, for any $\\eps > 0$, and to obtain a nearly optimal $(1-e^{-1}-\\eps)-$approximation ratio for the monotone case, for any $\\eps>0$. We further show that the probabilistic domain ...
Directory of Open Access Journals (Sweden)
F. Mavromatakis
2007-05-01
Full Text Available In this work we explore the effect of the contribution of the solar spectrum to the recorded signal in wavelengths outside the typical 940-nm filter's bandwidth. We use gaussian-shaped filters as well as actual filter transmission curves to study the implications imposed by the non-zero out-of-band contribution to the coefficients used to derive precipitable water from the measured water vapour band transmittance. The moderate-resolution SMARTS radiative transfer code is used to predict the incident spectrum outside the filter bandpass for different atmospheres, solar geometries and aerosol optical depths. The high-resolution LBLRTM radiative transfer code is used to calculate the water vapour transmittance in the 940 nm band. The absolute level of the out-of-band transmittance has been chosen to range from 10^{−6} to 10^{−4}, and typical response curves of commercially available silicon photodiodes are included into the calculations. It is shown that if the out-of-band transmittance effect is neglected, as is generally the case, then the derived columnar water vapour is systematically underestimated by a few percents. The actual error depends on the specific out-of-band transmittance, optical air mass of observation and water vapour amount. We apply published parameterized transmittance functions to determine the filter coefficients. We also introduce an improved, three-parameter, fitting function that can describe the theoretical data accurately, with significantly less residual effects than with the existing functions. Further investigations will use experimental data from field campaigns to validate these findings.
An Effort for Improving Transport Efficiency of Plasma in Acurved Magnet Filter
Institute of Scientific and Technical Information of China (English)
HU Yawei; LI Liuhe; XU Ming; LIU You-ming; CAI Xun; CHU P K
2004-01-01
In this article an effort was made to increase the efficiency of plasma transmission by using a additional wire netting between the substrate and the filter duct which was floated. The substrate was biased with a negative voltage or connected to anode, respectively. the parameters of the exited plasma and ion saturation current are examined by Langmuir probe and current collector plate. It was found that When the wire netting is connected to apositive voltage and the substrate is biased with a negative voltage, the ion saturation current and ion density had obviously improvement . The result proved that this method could improve the ion saturation current and ion density.
Analog filtering methods improve leading edge timing performance of multiplexed SiPMs
Bieniosek, M. F.; Cates, J. W.; Grant, A. M.; Levin, C. S.
2016-08-01
Multiplexing many SiPMs to a single readout channel is an attractive option to reduce the readout complexity of high performance time of flight (TOF) PET systems. However, the additional dark counts and shaping from each SiPM cause significant baseline fluctuations in the output waveform, degrading timing measurements using a leading edge threshold. This work proposes the use of a simple analog filtering network to reduce the baseline fluctuations in highly multiplexed SiPM readouts. With 16 SiPMs multiplexed, the FWHM coincident timing resolution for single 3~\\text{mm}× 3~\\text{mm}× 20 mm LYSO crystals was improved from 401 ± 4 ps without filtering to 248 ± 5 ps with filtering. With 4 SiPMs multiplexed, using an array of 3~\\text{mm}× 3~\\text{mm}× 20 mm LFS crystals the mean time resolution was improved from 436 ± 6 ps to 249 ± 2 ps. Position information was acquired with a novel binary positioning network. All experiments were performed at room temperature with no active temperature regulation. These results show a promising technique for the construction of high performance multiplexed TOF PET readout systems using analog leading edge timing pickoff.
An Innovative Process to Improve Turbidity and Organics Removal by BAC Filters
Institute of Scientific and Technical Information of China (English)
MIAO Jia; ZHAO Qingliang; WANG Baozhen; LI Ji; ZHANG Jinsong
2006-01-01
The turbidity criterion for the product water of a WTP according to the State Project ‘863' on the safeguard technology of drinking water in the southern areas of China is 0.1 NTU. The turbidity removal in the activated carbon filter was analyzed in a pilot-scale test and an innovative technology to improve the turbidity removal in a biologically activated carbon (BAC) filter was put forward in order to meet the criterion. Experimental results showed that the enhanced filtration by adding polymerized aluminium chloride (PAC) into the BAC filter was quite effective in turbidity control. The effluent turbidity was kept at a stable level (mean) of 0.033 NTU with a high removal of about 80% for influent turbidity of 0.110 -0240 NTU with an addition of PAC at 0.05 mg L-1, meeting the requirement for filtrate turbidity equal to or less than 0.1NTUC totally. In addition, the larger the PAC dosage was, the lower the effluent turbidity was. However, further improvement of turbidity removal was not obvious for PAC dosages beyond 0.10 mg L- 1, and an optimal PAC dosage in the range of 0.05 - 0.10 mg L- 1 was proposed.
Institute of Scientific and Technical Information of China (English)
林列; 王湘晖; 王肇圻; 母国光
2003-01-01
A filter with two zones phase-shifted by π is proposed to improve the axial resolution of confocal microscopes with a finite-sized detector. The optimum axial resolution for a given size of the detector can be achieved by adjusting the zone boundary of the filter. The experimental results are well in agreement with the theoretical predictions.
Zhiyang Hu; Shuhong Xu; Xiaojing Xu; Zhaochong Wang; Zhuyuan Wang; Chunlei Wang; Yiping Cui
2015-01-01
In optics, when polychromatic light is filtered by an optical filter, the monochromaticity of the light can be improved. In this work, we reported that Ag dopant atoms could be used as an optical filter for nanosized Mn:ZnSe quantum dots (QDs). If no Ag doping, aqueous Mn:ZnSe QDs have low monochromaticity due to coexisting of strong ZnSe band gap emission, ZnSe trap emission, and Mn dopant emission. After doping of Ag into QDs, ZnSe band gap and ZnSe trap emissions can be filtered, leaving o...
Tehsin, Sara; Rehman, Saad; Awan, Ahmad B.; Chaudry, Qaiser; Abbas, Muhammad; Young, Rupert; Asif, Afia
2016-04-01
Sensitivity to the variations in the reference image is a major concern when recognizing target objects. A combinational framework of correlation filters and logarithmic transformation has been previously reported to resolve this issue alongside catering for scale and rotation changes of the object in the presence of distortion and noise. In this paper, we have extended the work to include the influence of different logarithmic bases on the resultant correlation plane. The meaningful changes in correlation parameters along with contraction/expansion in the correlation plane peak have been identified under different scenarios. Based on our research, we propose some specific log bases to be used in logarithmically transformed correlation filters for achieving suitable tolerance to different variations. The study is based upon testing a range of logarithmic bases for different situations and finding an optimal logarithmic base for each particular set of distortions. Our results show improved correlation and target detection accuracies.
Olivares, Alberto; Górriz, J M; Ramírez, J; Olivares, G
2016-05-01
With the advent of miniaturized inertial sensors many systems have been developed within the last decade to study and analyze human motion and posture, specially in the medical field. Data measured by the sensors are usually processed by algorithms based on Kalman Filters in order to estimate the orientation of the body parts under study. These filters traditionally include fixed parameters, such as the process and observation noise variances, whose value has large influence in the overall performance. It has been demonstrated that the optimal value of these parameters differs considerably for different motion intensities. Therefore, in this work, we show that, by applying frequency analysis to determine motion intensity, and varying the formerly fixed parameters accordingly, the overall precision of orientation estimation algorithms can be improved, therefore providing physicians with reliable objective data they can use in their daily practice.
Zhang, Hao; Niu, Yanxiong; Lu, Jiazhen; Zhang, He
2016-11-20
Angular velocity information is a requisite for a spacecraft guidance, navigation, and control system. In this paper, an approach for angular velocity estimation based merely on star vector measurement with an improved current statistical model Kalman filter is proposed. High-precision angular velocity estimation can be achieved under dynamic conditions. The amount of calculation is also reduced compared to a Kalman filter. Different trajectories are simulated to test this approach, and experiments with real starry sky observation are implemented for further confirmation. The estimation accuracy is proved to be better than 10-4 rad/s under various conditions. Both the simulation and the experiment demonstrate that the described approach is effective and shows an excellent performance under both static and dynamic conditions.
Monotone Rank and Separations in Computational Complexity
Li, Yang D
2011-01-01
In the paper, we introduce the concept of monotone rank, and using it as a powerful tool, we obtain several important and strong separation results in computational complexity. We show a super-exponential separation between monotone and non-monotone computation in the non-commutative model, and thus give the answer to a longstanding open problem posed by Nisan \\cite{Nis1991} in algebraic complexity. More specifically, we exhibit a homogeneous algebraic function $f$ of degree $d$ ($d$ even) on $n$ variables with the monotone algebraic branching program (ABP) complexity $\\Omega(n^{d/2})$ and the non-monotone ABP complexity $O(d^2)$. We propose a relaxed version of the famous Bell's theorem\\cite{Bel1964}\\cite{CHSH1969}. Bell's theorem basically states that local hidden variable theory cannot predict the correlations produced by quantum mechanics, and therefore is an impossibility result. Bell's theorem heavily relies on the diversity of the measurements. We prove that even if we fix the measurement, infinite amo...
An Improved Unscented Kalman Filter Based Decoder for Cortical Brain-Machine Interfaces
Li, Simin; Li, Jie; Li, Zheng
2016-01-01
Brain-machine interfaces (BMIs) seek to connect brains with machines or computers directly, for application in areas such as prosthesis control. For this application, the accuracy of the decoding of movement intentions is crucial. We aim to improve accuracy by designing a better encoding model of primary motor cortical activity during hand movements and combining this with decoder engineering refinements, resulting in a new unscented Kalman filter based decoder, UKF2, which improves upon our previous unscented Kalman filter decoder, UKF1. The new encoding model includes novel acceleration magnitude, position-velocity interaction, and target-cursor-distance features (the decoder does not require target position as input, it is decoded). We add a novel probabilistic velocity threshold to better determine the user's intent to move. We combine these improvements with several other refinements suggested by others in the field. Data from two Rhesus monkeys indicate that the UKF2 generates offline reconstructions of hand movements (mean CC 0.851) significantly more accurately than the UKF1 (0.833) and the popular position-velocity Kalman filter (0.812). The encoding model of the UKF2 could predict the instantaneous firing rate of neurons (mean CC 0.210), given kinematic variables and past spiking, better than the encoding models of these two decoders (UKF1: 0.138, p-v Kalman: 0.098). In closed-loop experiments where each monkey controlled a computer cursor with each decoder in turn, the UKF2 facilitated faster task completion (mean 1.56 s vs. 2.05 s) and higher Fitts's Law bit rate (mean 0.738 bit/s vs. 0.584 bit/s) than the UKF1. These results suggest that the modeling and decoder engineering refinements of the UKF2 improve decoding performance. We believe they can be used to enhance other decoders as well. PMID:28066170
An Improved Unscented Kalman Filter Based Decoder for Cortical Brain-Machine Interfaces.
Li, Simin; Li, Jie; Li, Zheng
2016-01-01
Brain-machine interfaces (BMIs) seek to connect brains with machines or computers directly, for application in areas such as prosthesis control. For this application, the accuracy of the decoding of movement intentions is crucial. We aim to improve accuracy by designing a better encoding model of primary motor cortical activity during hand movements and combining this with decoder engineering refinements, resulting in a new unscented Kalman filter based decoder, UKF2, which improves upon our previous unscented Kalman filter decoder, UKF1. The new encoding model includes novel acceleration magnitude, position-velocity interaction, and target-cursor-distance features (the decoder does not require target position as input, it is decoded). We add a novel probabilistic velocity threshold to better determine the user's intent to move. We combine these improvements with several other refinements suggested by others in the field. Data from two Rhesus monkeys indicate that the UKF2 generates offline reconstructions of hand movements (mean CC 0.851) significantly more accurately than the UKF1 (0.833) and the popular position-velocity Kalman filter (0.812). The encoding model of the UKF2 could predict the instantaneous firing rate of neurons (mean CC 0.210), given kinematic variables and past spiking, better than the encoding models of these two decoders (UKF1: 0.138, p-v Kalman: 0.098). In closed-loop experiments where each monkey controlled a computer cursor with each decoder in turn, the UKF2 facilitated faster task completion (mean 1.56 s vs. 2.05 s) and higher Fitts's Law bit rate (mean 0.738 bit/s vs. 0.584 bit/s) than the UKF1. These results suggest that the modeling and decoder engineering refinements of the UKF2 improve decoding performance. We believe they can be used to enhance other decoders as well.
A Monotonic Precise Current DAC for Sensor Applications
Directory of Open Access Journals (Sweden)
P. Horsky
2008-12-01
Full Text Available In this paper a 17 bit monotonic precise current DAC for sensor applications is described. It is working in a harsh automotive environment in a wide temperature range with high output voltage swing and low current consumption. To guarantee monotonicity current division and segmentation techniques are used. To improve the output impedance, the accuracy and the voltage compliance of the DAC, two active cascoding loops and one follower loop are used. The resolution of the DAC is further increased by applying pulse width modulation to one fine LSB current. To achieve low power consumption unused coarse current sources are switched off. Several second order technological effects influencing final performance and circuits dealing with them are discussed.
Accuracy Improvement of ASTER Stereo Satellite Generated DEM Using Texture Filter
Institute of Scientific and Technical Information of China (English)
Mandla V. Ravibabu; Kamal Jain; Surendra Pal Singh; Naga Jyothi Meeniga
2010-01-01
The grid DEM (digital elevation model) generation can be from any of a number of sources: for instance, analogue to digital conversion of contour maps followed by application of the TIN model, or direct elevation point modelling via digital photogrammetry applied to airborne images or satellite images. Currently, apart from the deployment of point-clouds from LiDAR data acquisition, the generally favoured approach refers to applications of digital photogrammetry. One of the most important steps in such deployment is the stereo matching process for conjugation point (pixel) establishment: very difficult in modelling any homogenous areas like water cover or forest canopied areas due to the lack of distinct spatial features. As a result, application of automated procedures is sure to generate erroneous elevation values. In this paper, we present and apply a method for improving the quality of stereo DEMs generated via utilization of an entropy texture filter. The filter was applied for extraction of homogenous areas before stereo matching so that a statistical texture filter could then be applied for removing anomalous evaluation values prior to interpolation and accuracy assessment via deployment of a spatial correlation technique. For exemplification, we used a stereo pair of ASTER 1B images.
The use of stability bands to improve the performance of quadrupole mass filters
Sudakov, M. Yu.; Mamontov, E. V.
2017-01-01
The possibility of increasing the resolving power of quadrupole mass filters has been discussed. It has been shown that the limitations associated with the finite time of flight imposed by Von Zahn's rule are modified while using the islands of stability that appear when quadrupole is excited by the additional signals. By calculation of the exponential increment of growth of the oscillation amplitude the effect of the acceleration of mass separation and improvement of the peak shape, when the islands of stability are used for ion filtering, is explained. The case of the excitation by two signals at different frequencies has been studied theoretically. The conditions under which suppression of the first order resonance for one of the directions of motion is obtained. The direct modeling of the peak shape of the mass filter shows the possibility of obtaining a resolution of 10,000 with a time of flight of ions through the quadrupole of 100 cycles of the main RF supply, and low sensitivity of the new operating mode to the nonlinear field distortions in the quadrupoles with rods of circular cross sections.
Ge, Shuang-Chao; Deng, Ming; Chen, Kai; Li, Bin; Li, Yuan
2016-12-01
Time-domain induced polarization (TDIP) measurement is seriously affected by power line interference and other field noise. Moreover, existing TDIP instruments generally output only the apparent chargeability, without providing complete secondary field information. To increase the robustness of TDIP method against interference and obtain more detailed secondary field information, an improved dataprocessing algorithm is proposed here. This method includes an efficient digital notch filter which can effectively eliminate all the main components of the power line interference. Hardware model of this filter was constructed and Vhsic Hardware Description Language code for it was generated using Digital Signal Processor Builder. In addition, a time-location method was proposed to extract secondary field information in case of unexpected data loss or failure of the synchronous technologies. Finally, the validity and accuracy of the method and the notch filter were verified by using the Cole-Cole model implemented by SIMULINK software. Moreover, indoor and field tests confirmed the application effect of the algorithm in the fieldwork.
The monotonic and fatigue behavior of CFCCs
Energy Technology Data Exchange (ETDEWEB)
Miriyala, N.; Liaw, P.K.; McHargue, C.J. [Univ. of Tennessee, Knoxville, TN (United States); Snead, L.L. [Oak Ridge National Laboratory, TN (United States)
1996-04-01
Flexure tests were performed to study the fabric orientation effects on the monotonic and fatigue behavior of two commercially available continuous fiber reinforced ceramic composites (CFCCs), namely (i) Nicalon fiber fabric reinforced alumina (Al{sub 2}O{sub 3}) matrix composite fabricated by a direct molten metal oxidation (DIMOX) process and, (ii) Nicalon fiber fabric reinforced silicon carbide (SiC) matrix composite fabricated by an isothermal chemical vapor infiltration (ICVI) process. The fabric orientation effects on the monotonic and fatigue behavior were strong in the Nicalon/Al{sub 2}O{sub 3} composite, while they were relatively weak in the Nicalon/SiC composite.
Weighted monotonicity inequalities for unbounded operators
Hoa, Dinh Trung
2011-01-01
Let $\\tau$ be a faithful normal semifinite trace on a von Neumann algebra $\\mathcal{M}$. For a continuous nonnegative convex monotone nondecreasing function $f$ on convex subset $\\Omega$ of $\\mathbb{R}$ and weight nonnegative Borel function $w$ we consider weighted monotonicity inequalities of the form {equation*} \\tau(w(A)^{1/2}f(A)w(A)^{1/2}) \\le \\tau (w(A)^{1/2}f(B)w(A)^{1/2}), {equation*} where $A$ and $B$ are unbounded operators affiliated with respect to algebra $\\mathcal{M}$.
EMMA: An Efficient Massive Mapping Algorithm Using Improved Approximate Mapping Filtering
Institute of Scientific and Technical Information of China (English)
Xin ZHANG; Zhi-Wei CAO; Zhi-Xin LIN; Qing-Kang WANG; Yi-Xue LI
2006-01-01
Efficient massive mapping algorithm (EMMA), an algorithm on efficiently mapping massive cDNAs onto genomic sequences, has recently been developed. The process of mapping massive cDNAs onto genomic sequences has been improved using more approximate mapping filtering based on an enhanced suffix array coupled with a pruned fast hash table, algorithms of block alignment extensions, and k-longest paths. When compared with the classical BLAT software in this field, the computing of EMMA ranges from two to forty-one times faster under similar prediction precisions.
Kneissler, Jan; Stalph, Patrick O; Drugowitsch, Jan; Butz, Martin V
2014-01-01
It has been shown previously that the control of a robot arm can be efficiently learned using the XCSF learning classifier system, which is a nonlinear regression system based on evolutionary computation. So far, however, the predictive knowledge about how actual motor activity changes the state of the arm system has not been exploited. In this paper, we utilize the forward velocity kinematics knowledge of XCSF to alleviate the negative effect of noisy sensors for successful learning and control. We incorporate Kalman filtering for estimating successive arm positions, iteratively combining sensory readings with XCSF-based predictions of hand position changes over time. The filtered arm position is used to improve both trajectory planning and further learning of the forward velocity kinematics. We test the approach on a simulated kinematic robot arm model. The results show that the combination can improve learning and control performance significantly. However, it also shows that variance estimates of XCSF prediction may be underestimated, in which case self-delusional spiraling effects can hinder effective learning. Thus, we introduce a heuristic parameter, which can be motivated by theory, and which limits the influence of XCSF's predictions on its own further learning input. As a result, we obtain drastic improvements in noise tolerance, allowing the system to cope with more than 10 times higher noise levels.
An improved exponential filter for fast nonlinear registration of brain magnetic resonance images
Institute of Scientific and Technical Information of China (English)
Zhiying Long; Li Yao; Kewei Chen; Danling Peng
2009-01-01
A linear elastic convolution filter was derived from the eigenfunctions of the Navier-Stokes differential operator by Bro-Nielsen in order to match images with large deformations. Due to the complexity of constructing the elastic convolution filter, the algorithm's effi-ciency reduces rapidly with the increase in the image's size. In our previous work, a simple two-sided exponential filter with high efficiency was proposed to approximate an elastic filter. However, its poor smoothness may degenerate the performance. In this paper, a new expo-nential filter was constructed by utilizing a modified nonlinear curve fitting method to approximate the elastic filter. The new filter's good smoothness makes its performance comparable to an elastic filter. Its simple and separable form makes the algorithm's speed faster than the elastic filter. Furthermore, our experiments demonstrated that the new filter was suitable for both the elastic and fluid models.
Monotone Comparative Statics for the Industry Composition
DEFF Research Database (Denmark)
Laugesen, Anders Rosenstand
2015-01-01
We let heterogeneous firms face decisions on a number of complementary activities in a monopolistically-competitive industry. The endogenous level of competition and selection regarding entry and exit of firms introduces a wedge between monotone comparative statics (MCS) at the firm level and MCS...
On a Monotone Ill-posed Problem
Institute of Scientific and Technical Information of China (English)
Nguyen BUONG
2005-01-01
A class of a posteriori parameter choice strategies for the operator version of Tikhonovregularization (including variants of Morozov's and Arcangeli's methods) is proposed and used in investigating the rate of convergence of the regularized solution for ill-posed nonlinear equation involving a monotone operator in Banach space.
Population Monotonic Path Schemes for Simple Games
Ciftci, B.B.; Borm, P.E.M.; Hamers, H.J.M.
2006-01-01
A path scheme for a simple game is composed of a path, i.e., a sequence of coalitions that is formed during the coalition formation process and a scheme, i.e., a payoff vector for each coalition in the path.A path scheme is called population monotonic if a player's payoff does not decrease as the pa
Monotone method for nonlinear nonlocal hyperbolic problems
Directory of Open Access Journals (Sweden)
Azmy S. Ackleh
2003-02-01
Full Text Available We present recent results concerning the application of the monotone method for studying existence and uniqueness of solutions to general first-order nonlinear nonlocal hyperbolic problems. The limitations of comparison principles for such nonlocal problems are discussed. To overcome these limitations, we introduce new definitions for upper and lower solutions.
Limit points of the monotonic schemes
Salomon, J
2005-01-01
Many numerical simulations in quantum (bilinear) control use the monotonically convergent algorithms of Krotov (introduced by Tannor), Zhu & Rabitz or the general form of Maday & Turinici. This paper presents an analysis of the limit set of controls provided by these algorithms and a proof of convergence in a particular case.
REGULAR RELATIONS AND MONOTONE NORMAL ORDERED SPACES
Institute of Scientific and Technical Information of China (English)
XU XIAOQUAN; LIU YINGMING
2004-01-01
In this paper the classical theorem of Zareckii about regular relations is generalized and an intrinsic characterization of regularity is obtained. Based on the generalized Zareckii theorem and the intrinsic characterization of regularity, the authors give a characterization of monotone normality of ordered spaces. A new proof of the UrysohnNachbin lemma is presented which is quite different from the classical one.
Monotonicity and bounds on Bessel functions
Directory of Open Access Journals (Sweden)
Larry Landau
2000-07-01
Full Text Available survey my recent results on monotonicity with respect to order of general Bessel functions, which follow from a new identity and lead to best possible uniform bounds. Application may be made to the "spreading of the wave packet" for a free quantum particle on a lattice and to estimates for perturbative expansions.
Strong monotonicity for analytic ordinary differential equations
Directory of Open Access Journals (Sweden)
Sebastian Walcher
2009-09-01
Full Text Available We present a necessary and sufficient criterion for the flow of an analytic ordinary differential equation to be strongly monotone; equivalently, strongly order-preserving. The criterion is given in terms of the reducibility set of the derivative of the right-hand side. Some applications to systems relevant in biology and ecology, including nonlinear compartmental systems, are discussed.
A monotonic archive for pareto-coevolution.
de Jong, Edwin D
2007-01-01
Coevolution has already produced promising results, but its dynamic evaluation can lead to a variety of problems that prevent most algorithms from progressing monotonically. An important open question therefore is how progress towards a chosen solution concept can be achieved. A general solution concept for coevolution is obtained by viewing opponents or tests as objectives. In this setup known as Pareto-coevolution, the desired solution is the Pareto-optimal set. We present an archive that guarantees monotonicity for this solution concept. The algorithm is called the Incremental Pareto-Coevolution Archive (IPCA), and is based on Evolutionary Multi-Objective Optimization (EMOO). By virtue of its monotonicity, IPCA avoids regress even when combined with a highly explorative generator. This capacity is demonstrated on a challenging test problem requiring both exploration and reliability. IPCA maintains a highly specific selection of tests, but the size of the test archive nonetheless grows unboundedly. We therefore furthermore investigate how archive sizes may be limited while still providing approximate reliability. The LAyered Pareto-Coevolution Archive (LAPCA) maintains a limited number of layers of candidate solutions and tests, and thereby permits a trade-off between archive size and reliability. The algorithm is compared in experiments, and found to be more efficient than IPCA. The work demonstrates how the approximation of a monotonic algorithm can lead to algorithms that are sufficiently reliable in practice while offering better efficiency.
Limit properties of monotone matrix functions
Behrndt, Jussi; Hassi, Seppo; de Snoo, Henk; Wietsma, Rudi
2012-01-01
The basic objects in this paper are monotonically nondecreasing n x n matrix functions D(center dot) defined on some open interval l = (a, b) of R and their limit values D(a) and D(b) at the endpoints a and b which are, in general, selfadjoint relations in C-n. Certain space decompositions induced b
Concerns on Monotonic Imbalance Bounding Matching Methods
Yatracos, Yannis G.
2013-01-01
Concerns are expressed for the Monotonic Imbalance Bounding (MIB) property (Iacus et al. 2011) and for MIB matching because i) the definition of the MIB property leads to inconsistencies and the nature of the imbalance measure is not clearly defined, ii) MIB property does not generalize Equal Percent Bias Reducing (EPBR) property, iii) MIB matching does not provide statistical information available with EPBR matching.
Nonparametric confidence intervals for monotone functions
Groeneboom, P.; Jongbloed, G.
2015-01-01
We study nonparametric isotonic confidence intervals for monotone functions. In [Ann. Statist. 29 (2001) 1699–1731], pointwise confidence intervals, based on likelihood ratio tests using the restricted and unrestricted MLE in the current status model, are introduced. We extend the method to the trea
Competitive learning of monotone Boolean functions
2014-01-01
We apply competitive analysis onto the problem of minimizing the number of queries to an oracle to completely reconstruct a given monotone Boolean function. Besides lower and upper bounds on the competitivity we determine optimal deterministic online algorithms for the smallest problem instances.
Nonparametric confidence intervals for monotone functions
Groeneboom, P.; Jongbloed, G.
2015-01-01
We study nonparametric isotonic confidence intervals for monotone functions. In [Ann. Statist. 29 (2001) 1699–1731], pointwise confidence intervals, based on likelihood ratio tests using the restricted and unrestricted MLE in the current status model, are introduced. We extend the method to the
Edit Distance to Monotonicity in Sliding Windows
DEFF Research Database (Denmark)
Chan, Ho-Leung; Lam, Tak-Wah; Lee, Lap Kei
2011-01-01
of a data stream is becoming well-understood over the past few years. Motivated by applications on network quality monitoring, we extend the study to estimating the edit distance to monotonicity of a sliding window covering the w most recent items in the stream for any w ≥ 1. We give a deterministic...
New concurrent iterative methods with monotonic convergence
Energy Technology Data Exchange (ETDEWEB)
Yao, Qingchuan [Michigan State Univ., East Lansing, MI (United States)
1996-12-31
This paper proposes the new concurrent iterative methods without using any derivatives for finding all zeros of polynomials simultaneously. The new methods are of monotonic convergence for both simple and multiple real-zeros of polynomials and are quadratically convergent. The corresponding accelerated concurrent iterative methods are obtained too. The new methods are good candidates for the application in solving symmetric eigenproblems.
Classification Trees for Problems with Monotonicity Constraints
R. Potharst (Rob); A.J. Feelders
2002-01-01
textabstractFor classification problems with ordinal attributes very often the class attribute should increase with each or some of the explaining attributes. These are called classification problems with monotonicity constraints. Classical decision tree algorithms such as CART or C4.5 generally do
Water risk assessment in China based on the improved Water Risk Filter
Hong, G.; Yaqin, Q.; Qiong, L.; Cunwen, N.; Na, W.; Jiajia, L.; Jongde, G.; Na, Z.; Xiangyi, D.
2014-09-01
Finding an effective way to deal with the water crisis and the relationship between water and development is a major issue for all levels of government and different economic sectors across the world. Scientific understanding of water risk is the basis for achieving a scientific relationship between water and development, and water risk assessment is currently an important research focus. To effectively deal with the global water crisis, the World Wide Fund for Nature and German Investment and Development Company Limited proposed the concept of water risk and released an online Water Risk Filter in March 2012, which has been applied to at least 85 countries. To comprehensively and accurately reflect the situation of water risk in China, this study adjusts the water risk assessment indicators in the Water Risk Filter, taking the actual situation in China and the difficulty of obtaining the information about the indicators into account, and proposes an index system for water risk evaluation for China which consists of physical risk, regulatory risk and reputational risk. The improved Water Risk Filter is further used to assess the sources and causes of the water risks in 10 first-class and seven second-class water resource areas (WRAs). The results indicate that the water risk for the whole country is generally medium and low, while those for different regions in the country vary greatly, and those for southern regions are generally lower than those for northern regions. Government regulatory and policy implementation as well as media supervision in northern regions should be strengthened to reduce the water risk. The research results may provide decision support and references for both governments and industrial enterprises in identifying water risks, formulating prevention and control policies, and improving water resources management in China.
Improving Hydrologic Data Assimilation by a Multivariate Particle Filter-Markov Chain Monte Carlo
Yan, H.; DeChant, C. M.; Moradkhani, H.
2014-12-01
Data assimilation (DA) is a popular method for merging information from multiple sources (i.e. models and remotely sensing), leading to improved hydrologic prediction. With the increasing availability of satellite observations (such as soil moisture) in recent years, DA is emerging in operational forecast systems. Although these techniques have seen widespread application, developmental research has continued to further refine their effectiveness. This presentation will examine potential improvements to the Particle Filter (PF) through the inclusion of multivariate correlation structures. Applications of the PF typically rely on univariate DA schemes (such as assimilating the outlet observed discharge), and multivariate schemes generally ignore the spatial correlation of the observations. In this study, a multivariate DA scheme is proposed by introducing geostatistics into the newly developed particle filter with Markov chain Monte Carlo (PF-MCMC) method. This new method is assessed by a case study over one of the basin with natural hydrologic process in Model Parameter Estimation Experiment (MOPEX), located in Arizona. The multivariate PF-MCMC method is used to assimilate the Advanced Scatterometer (ASCAT) grid (12.5 km) soil moisture retrievals and the observed streamflow in five gages (four inlet and one outlet gages) into the Sacramento Soil Moisture Accounting (SAC-SMA) model for the same scale (12.5 km), leading to greater skill in hydrologic predictions.
Automatic digital filtering for the accuracy improving of a digital holographic measurement system
Matrecano, Marcella; Miccio, Lisa; Persano, Anna; Quaranta, Fabio; Siciliano, Pietro; Ferraro, Pietro
2014-05-01
Digital holography (DH) is a well-established interferometric tool in optical metrology allowing the investigation of engineered surface shapes with microscale lateral resolution and nanoscale axial precision. With the advent of charged coupled devices (CCDs) with smaller pixel sizes, high speed computers and greater pixel numbers, DH became a very feasible technology which offers new possibilities for a large variety of applications. DH presents numerous advantages such as the direct access to the phase information, numerical correction of optical aberrations and the ability of a numerical refocusing from a single hologram. Furthermore, as an interferometric method, DH offers both a nodestructive and no-contact approach to very fragile objects combined with flexibility and a high sensitivity to geometric quantities such as thicknesses and displacements. These features recommend it for the solution of many imaging and measurements problems, such as microelectro-optomechanical systems (MEMS/MEOMS) inspection and characterization. In this work, we propose to improve the performance of a DH measurement on MEMS devices, through digital filters. We have developed an automatic procedure, inserted in the hologram reconstruction process, to selectively filter the hologram spectrum. The purpose is to provide very few noisy reconstructed images, thus increasing the accuracy of the conveyed information and measures performed on images. Furthermore, improving the image quality, we aim to make this technique application as simple and as accurate as possible.
Zhang, X L; Su, G F; Yuan, H Y; Chen, J G; Huang, Q Y
2014-09-15
Atmospheric dispersion models play an important role in nuclear power plant accident management. A reliable estimation of radioactive material distribution in short range (about 50 km) is in urgent need for population sheltering and evacuation planning. However, the meteorological data and the source term which greatly influence the accuracy of the atmospheric dispersion models are usually poorly known at the early phase of the emergency. In this study, a modified ensemble Kalman filter data assimilation method in conjunction with a Lagrangian puff-model is proposed to simultaneously improve the model prediction and reconstruct the source terms for short range atmospheric dispersion using the off-site environmental monitoring data. Four main uncertainty parameters are considered: source release rate, plume rise height, wind speed and wind direction. Twin experiments show that the method effectively improves the predicted concentration distribution, and the temporal profiles of source release rate and plume rise height are also successfully reconstructed. Moreover, the time lag in the response of ensemble Kalman filter is shortened. The method proposed here can be a useful tool not only in the nuclear power plant accident emergency management but also in other similar situation where hazardous material is released into the atmosphere.
Sahadevan, Anand S.; Routray, Aurobinda; Das, Bhabani S.; Ahmad, Saquib
2016-04-01
Bilateral filter (BF) theory is applied to integrate spatial contextual information into the spectral domain for improving the accuracy of the support vector machine (SVM) classifier. The proposed classification framework is a two-stage process. First, an edge-preserved smoothing is carried out on a hyperspectral image (HSI). Then, the SVM multiclass classifier is applied on the smoothed HSI. One of the advantages of the BF-based implementation is that it considers the spatial as well as spectral closeness for smoothing the HSI. Therefore, the proposed method provides better smoothing in the homogeneous region and preserves the image details, which in turn improves the separability between the classes. The performance of the proposed method is tested using benchmark HSIs obtained from the airborne-visible-infrared-imaging-spectrometer (AVIRIS) and the reflective-optics-system-imaging-spectrometer (ROSIS) sensors. Experimental results demonstrate the effectiveness of the edge-preserved filtering in the classification of the HSI. Average accuracies (with 10% training samples) of the proposed classification framework are 99.04%, 98.11%, and 96.42% for AVIRIS-Salinas, ROSIS-Pavia University, and AVIRIS-Indian Pines images, respectively. Since the proposed method follows a combination of BF and the SVM formulations, it will be quite simple and practical to implement in real applications.
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.
A Finger Vein Recognition Method Using Improved Oriented Filter and Elastic Registration
Directory of Open Access Journals (Sweden)
Ma Hui
2013-07-01
Full Text Available In order to reduce the influence of relative position deviation and angle deviation between minutia point sets caused by external factors when finger vein images are obtained, a finger vein recognition method using elastic registration is presented. The proposed algorithm is based on an improved neighborhood direction template and oriented filter template which facilitates the enhancement of the finger vein image while taking full account of image orientation. Elastic registration is then applied to matching of feature points within the predefined angle and radius. Applying the idea of elastic registration to existing finger vein recognition method removes the need for perfect matching between corresponding feature points and has shown to be an effective method for dealing with the problem of nonlinear distortion of images. Experimental results show that this algorithm not only overcomes the limitations of traditional point matching method, but also effectively improves the recognition performance of the system.
Directory of Open Access Journals (Sweden)
Yong Li
2014-12-01
Full Text Available Airborne light detection and ranging (lidar has become a powerful support for acquiring geospatial data in numerous geospatial applications and analyses. However, the process of extracting ground points accurately and effectively from raw point clouds remains a big challenge. This study presents an improved top-hat filter with a sloped brim to enhance the robustness of ground point extraction for complex objects and terrains. The top-hat transformation is executed and the elevation change intensity of the transitions between the obtained top-hats and outer brims is inspected to suppress the omission error caused by protruding terrain features. Finally, the nonground objects of complex structures, such as multilayer buildings, are identified by the brim filter that is extended outward. The performance of the proposed filter in various environments is evaluated using diverse datasets with difficult cases. The comparison of the proposed filter with the commercial software Terrasolid TerraScan and other popular filtering algorithms demonstrates the applicability and effectiveness of this filter. Experimental results show that the proposed filter has great promise in terms of its application in various types of landscapes. Abrupt terrain features with dramatic elevation changes are well preserved, and diverse objects with complicated shapes are effectively removed. This filter has minimal omission and commission error oscillation for different test areas and thus demonstrates a stable and reliable performance in diverse landscapes. In addition, the proposed algorithm has high computational efficiency because of its simple and efficient data structure and implementation.
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.
Wang, Zhenwu; Hut, Rolf; van de Giesen, Nick
2017-04-01
Particle filtering is a nonlinear and non-Gaussian dynamical filtering system. It has found widespread applications in hydrological data assimilation. In order to solve the loss of particle diversity exiting in resampling process of particle filter, this research proposes an improved particle filter algorithm using genetic algorithm optimization and Gamma test. This method combines the genetic algorithm and Gamma test into the resampling procedure of particle filter to improve the adaptability and performance of particle filter in data assimilation. First, the particles are classified to three different groups based on resampling method. The particles with high weight values remain unchanged. Then genetic algorithm is used to cross and variate the rest of the particles. In the process of the optimization, the Gamma test method is applied for monitoring the quality of the new generated particles. When the gamma statistic stays stable, the algorithm will end the optimization and continue to perturb next observations in particle algorithm. The algorithm is illustrated for the three-dimensional Lorenz model and the much more complex 40-dimensional Lorenz model. The results demonstrate this method can keep the diversity of the particles and enhance the performance of the particle filter, leading to the promising conjecture that the method is applicable to realistic hydrological problems.
Improved Particle Filter for Passive Target Tracking%改进粒子滤波在被动目标跟踪中的应用
Institute of Scientific and Technical Information of China (English)
邓小龙; 谢剑英; 杨煜普
2005-01-01
As a new method for dealing with any nonlinear or non-Gaussian distributions, based on the Monte Carlo methods and Bayesian filtering, particle filters (PF) are favored by researchers and widely applied in many fields. Based on particle filtering, an improved extended Kalman filter (EKF) proposal distribution is presented. Evaluation of the weights is simplified and other improved techniques including the residual resampling step and Markov Chain Monte Carlo method are introduced for target tracking. Performances of the EKF, basic PF and the improved PF are compared in target tracking examples. The simulation results confirm that the improved particle filter outperforms the others.
Qian, Kun; Zhou, Huixin; Rong, Shenghui; Wang, Bingjian; Cheng, Kuanhong
2017-05-01
Infrared small target tracking plays an important role in applications including military reconnaissance, early warning and terminal guidance. In this paper, an effective algorithm based on the Singular Value Decomposition (SVD) and the improved Kernelized Correlation Filter (KCF) is presented for infrared small target tracking. Firstly, the super performance of the SVD-based algorithm is that it takes advantage of the target's global information and obtains a background estimation of an infrared image. A dim target is enhanced by subtracting the corresponding estimated background with update from the original image. Secondly, the KCF algorithm is combined with Gaussian Curvature Filter (GCF) to eliminate the excursion problem. The GCF technology is adopted to preserve the edge and eliminate the noise of the base sample in the KCF algorithm, helping to calculate the classifier parameter for a small target. At last, the target position is estimated with a response map, which is obtained via the kernelized classifier. Experimental results demonstrate that the presented algorithm performs favorably in terms of efficiency and accuracy, compared with several state-of-the-art algorithms.
Do low-cost ceramic water filters improve water security in rural South Africa?
Lange, Jens; Materne, Tineke; Grüner, Jörg
2016-10-01
This study examined the performance of a low-cost ceramic candle filter system (CCFS) for point of use (POU) drinking water treatment in the village of Hobeni, Eastern Cape Province, South Africa. CCFSs were distributed in Hobeni and a survey was carried out among their users. The performance of 51 CCFSs was evaluated by dip slides and related to human factors. Already after two-thirds of their specified lifetime, none of the distributed CCFSs produced water without distinct contamination, and more than one-third even deteriorated in hygienic water quality. Besides the water source (springs were preferable compared to river or rain water), a high water throughput was the dominant reason for poor CCFS performance. A stepwise laboratory test documented the negative effects of repeated loading and ambient field temperatures. These findings suggest that not every CCFS type per se guarantees improved drinking water security and that the efficiency of low-cost systems should continuously be monitored. For this purpose, dip slides were found to be a cost-efficient alternative to standard laboratory tests. They consistently underestimated microbial counts but can be used by laypersons and hence by the users themselves to assess critical contamination of their filter systems.
Improved shielding and filtering applied to immunity enhancement of underground gas sensors
Institute of Scientific and Technical Information of China (English)
SUN Ji-ping; MA Feng-ying
2008-01-01
In order to eliminate false alarms, issued by gas sensors in coal mining, caused by Electromagnetic Interference (EMI), both computer simulation and field measurements were introduced to analyze the underground EMI distribution. A simplified model of a sensor with metal enclosure was established and the effects of shielding properties about the enclosure aperture were studied. Because the haulage motor is the moving EMI source, varying with time, the onsite flameproof measuring instruments cannot accomplish synchronous measurements of electromagnetic field vectors. To simplify the field measurements, two sensors, one with a lead and the other without a lead, were chosen to conduct the contrasting measurements. The EMI current caused by the perforation lead was comparatively strong and therefore nickel zinc ferrite beads were used to cut off the EMI propagation paths. The peak value of the interference current was reduced by 20%-70% with the beads. After switching on the sensor power, the sensors still occasionally gave false alarms when the switch of nearby large-scale electric equipment was operated. A complex EMI filter was used and the'EMI attenuated markedly. The running results demonstrated that false alarms had been eliminated. We conclude that the improved shielding and filtering are highly significant in enhancing the immunity of the gas sensor.
Improving the filterability and solid density of ranitidine hydrochloride Form 1.
Mirmehrabi, Mahmoud; Rohani, Sohrab; Murthy, K S Keshava; Radatus, Bruno
2004-07-01
Ranitidine hydrochloride Form 1 produced by the original method (Price et al., 1978 US patent) has poor filtration and drying characteristics, which make it less desirable commercially in comparison with Form 2. This article shows that the operating parameters have significant influence on the final properties of Form 1. In terms of filterability and solid bulk density, it was found that at a higher temperature (approximately 48 degrees C), the viscosity of the slurry decreased and improved product quality as compared with operating at room temperature (approximately 25 degrees C). It was found that the rapid addition of acid to the ranitidine base increased product density but led to higher residual solvent inclusion. The presence of excess ranitidine base in the solution and also the manner of reactant addition had a significant influence on the onset of nucleation and the rate of crystallization. The best results in terms of filterability and bulk solid density were obtained using an initial pH of 5.3 and then increasing it to 6.3-6.4 after the onset of nucleation.
Improving the phase measurement by the apodization filter in the digital holography
Chang, Shifeng; Wang, Dayong; Wang, Yunxin; Zhao, Jie; Rong, Lu
2012-11-01
Due to the finite size of the hologram aperture in digital holography, high frequency intensity and phase fluctuations along the edges of the images, which reduce the precision of phase measurement. In this paper, the apodization filters are applied to improve the phase measurement in the digital holography. Firstly, the experimental setup of the lensless Fourier transform digital holography is built, where the sample is a standard phase grating with the grating constant of 300μm and the depth of 150nm. Then, apodization filters are applied to phase measurement of the sample with three kinds of the window functions: Tukey window, Hanning window and Blackman window, respectively. Finally, the results were compared to the detection data given by the commercial white-light interferometer. It is shown that aperture diffraction effects can be reduced by the digital apodization, and the phase measurement with the apodization is more accurate than in the unapodized case. Meanwhile, the Blackman window function produces better effect than the other two window functions in the measurement of the standard phase grating.
An Improved Double Fuzzy PI Controller For Shunt Active Power Filter DC Bus Regulation
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Nabil ELHAJ
2015-06-01
Full Text Available This paper targets to demonstrate the importance of the choice of the algorithm references detection to be applied with a double fuzzy PI corrector (DFPI for the control and the regulation of a shunt active power filter (SAPF DC bus voltage. In a previous work, the synchronous reference frame (SRF algorithm was applied and gave satisfactory results. In the present paper, the SRF is substituted by the positive sequence of the fundamental of the source voltage algorithm (PSF which offered better results regarding the power quality of the considered main utility feeding a variable DC RL load throughout a diode bridge. The results were carried out using computer simulation perfomed under MATLAB/Simulink environment. To make the obtained results more convenient, a comparison between the couples (SRF, PI, (PSF, PI, (SRF, DFPI, (PSF, DFPI is added to prove the effectiveness of the couple (PSF, DFPI in satisfying the compromise between a good regulation of the SAPF DC bus voltage and a good quality of filtering resulting in an improved quality of power.
Shen, Jyi-Lai; Huang, Hau-Min; Lee, Yueh-Chien; Huang, Chia-Chih; Lin, Huang-Cuang; Lin, Chin-Yuan
2009-01-01
To form a low noise figure and uniform shortpass band in optical fiber communications an improved automatic filtered power control (AFPC) pumping method is proposed here. A modulated single laser signal was entered in a closed feedback loop, in which the erbium-doped fiber amplifier (EDFA) was used as a part of the AFPC loop. Owing to the constant filtered signal and the quadrature phase shift delay inside the feedback loop, an optical pass band was uniformly formed. This EDFA attains high performance with a low noise figure simultaneously. The method was successfully applied to the fabrication of practical 12.0 m length of erbium-doped fiber pumped at 980 nm wavelength and 20 dBm power. Experiments prove that the signal gain of the loop remain flat in the range of 18.2 to 22.4 dB with a worst case error of ±0.5 dB and the noise figure was reduced by 2.2 dB at optimal, which correspond to a shortpass range of 40 nm band pass from 1525 nm to 1565 nm in wavelength. Of course, it should be possible to extent the system performance to all pumping configurations for semiconductor optical amplifiers. This provides the simplest and most economical way to transmit a well-defined band of modulated laser signal and to reject all other unwanted radiation.
Improved broadband solar irradiance from the multi-filter rotating shadowband radiometer
Energy Technology Data Exchange (ETDEWEB)
Michalsky, J.J.; Augustine, J.A. [National Oceanic and Atmospheric Administration, Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305 (United States); Kiedron, P.W. [Cooperative Institute for Research in Environmental Sciences, University of Colorado, 325 Broadway, Boulder, CO 80305 (United States)
2009-12-15
Approximations to total and diffuse horizontal and direct normal, broadband solar irradiance (280-4000 nm) can be obtained from the multi-filter rotating shadowband radiometer (MFRSR) using the unfiltered silicon channel of this seven-channel instrument. However, the unfiltered silicon channel only responds to wavelengths between 300 and 1100 nm and does not have a uniform spectral response. In contrast, the best, more expensive, first-class, thermopile-based radiometers respond fairly uniformly to all solar wavelengths. While the total horizontal and direct normal solar irradiance measurements made with the MFRSR unfiltered silicon channel are reasonable if carefully calibrated with a thermopile radiometer, the diffuse horizontal irradiance calibrated in this way has a large bias. These issues are common to all inexpensive, silicon-cell, solar pyranometers. In this paper we use a multivariate, linear regression technique for approximating the thermopile-measured total, diffuse, and direct broadband solar irradiances using the six, narrowband filters and the open-channel of an MFRSR. The calibration of the MFRSR for broadband solar by comparing various combinations of MFRSR channels to first-class thermopile instruments is illustrated, and methods to track the instrument response during field deployments are investigated. We also suggest an approach to calibrate the open-channel for all three components that could improve measurements that are made using typical, commercial, silicon-cell pyranometers. (author)
Improved DCT-based nonlocal means filter for MR images denoising.
Hu, Jinrong; Pu, Yifei; Wu, Xi; Zhang, Yi; Zhou, Jiliu
2012-01-01
The nonlocal means (NLM) filter has been proven to be an efficient feature-preserved denoising method and can be applied to remove noise in the magnetic resonance (MR) images. To suppress noise more efficiently, we present a novel NLM filter based on the discrete cosine transform (DCT). Instead of computing similarity weights using the gray level information directly, the proposed method calculates similarity weights in the DCT subspace of neighborhood. Due to promising characteristics of DCT, such as low data correlation and high energy compaction, the proposed filter is naturally endowed with more accurate estimation of weights thus enhances denoising effectively. The performance of the proposed filter is evaluated qualitatively and quantitatively together with two other NLM filters, namely, the original NLM filter and the unbiased NLM (UNLM) filter. Experimental results demonstrate that the proposed filter achieves better denoising performance in MRI compared to the others.
Sen, Subhamoy; Crinière, Antoine; Mevel, Laurent; Cerou, Frederic; Dumoulin, Jean
2017-04-01
within a PF environment that estimates the parameters. This facilitates employing relatively less expensive linear KF for linear state estimation problem while costly PF is employed only for parameter estimation. Additionally, the proposed algorithm also takes care of those systems for which system and measurement noises are not uncorrelated as it is commonly idealized in standard filtering algorithms. As an example, for mechanical systems under ambient vibration it happens when acceleration response is considered as measurement. Thus the process and measurement noise in these system descriptions are obviously correlated. For this, an improved description for the Kalman gain is developed. Further, to enhance the consistency of particle filtering based parameter estimation involving high dimensional parameter space, a new temporal evolution strategy for the particles is defined. This strategy aims at restricting the solution from diverging (up to the point of no return) because of an isolated event of infeasible estimation which is very much likely especially when dealing with high dimensional parameter space.
Monotone operators and "bigger conjugate" functions
Bauschke, Heinz H; Wang, Xianfu; Yao, Liangjin
2011-01-01
We study a question posed by Stephen Simons in his 2008 monograph involving "bigger conjugate" (BC) functions and the partial infimal convolution. As Simons demonstrated in his monograph, these function have been crucial to the understanding and advancement of the state-of-the-art of harder problems in monotone operator theory, especially the sum problem. In this paper, we provide some tools for further analysis of BC--functions which allow us to answer Simons' problem in the negative. We are also able to refute a similar but much harder conjecture which would have generalized a classical result of Br\\'ezis, Crandall and Pazy. Our work also reinforces the importance of understanding unbounded skew linear relations to construct monotone operators with unexpected properties.
Complexity of Non-Monotonic Logics
Thomas, Michael
2010-01-01
Over the past few decades, non-monotonic reasoning has developed to be one of the most important topics in computational logic and artificial intelligence. Different ways to introduce non-monotonic aspects to classical logic have been considered, e.g., extension with default rules, extension with modal belief operators, or modification of the semantics. In this survey we consider a logical formalism from each of the above possibilities, namely Reiter's default logic, Moore's autoepistemic logic and McCarthy's circumscription. Additionally, we consider abduction, where one is not interested in inferences from a given knowledge base but in computing possible explanations for an observation with respect to a given knowledge base. Complexity results for different reasoning tasks for propositional variants of these logics have been studied already in the nineties. In recent years, however, a renewed interest in complexity issues can be observed. One current focal approach is to consider parameterized problems and ...
Linear Inviscid Damping for Monotone Shear Flows
Zillinger, Christian
2014-01-01
In this article we prove linear stability, inviscid damping and scattering of the 2D Euler equations around regular, strictly monotone shear flows $(U(y),0)$ in a periodic channel under Sobolev perturbations. We treat the settings of an infinite channel, $\\mathbb{T} \\times \\mathbb{R}$, as well as a finite channel, $\\mathbb{T} \\times [0,1]$, with impermeable boundary. We first prove inviscid damping with optimal algebraic rates for strictly monotone shear flows under the assumption of controlling the regularity of the scattered vorticity. Subsequently, we establish linear stability of the scattering equation in Sobolev spaces under perturbations which are of not too large wave-length with respect to $x$, depending on $U''$.
Edit Distance to Monotonicity in Sliding Windows
Chan, Ho-Leung; Lee, Lap-Kei; Pan, Jiangwei; Ting, Hing-Fung; Zhang, Qin
2011-01-01
Given a stream of items each associated with a numerical value, its edit distance to monotonicity is the minimum number of items to remove so that the remaining items are non-decreasing with respect to the numerical value. The space complexity of estimating the edit distance to monotonicity of a data stream is becoming well-understood over the past few years. Motivated by applications on network quality monitoring, we extend the study to estimating the edit distance to monotonicity of a sliding window covering the $w$ most recent items in the stream for any $w \\ge 1$. We give a deterministic algorithm which can return an estimate within a factor of $(4+\\eps)$ using $O(\\frac{1}{\\eps^2} \\log^2(\\eps w))$ space. We also extend the study in two directions. First, we consider a stream where each item is associated with a value from a partial ordered set. We give a randomized $(4+\\epsilon)$-approximate algorithm using $O(\\frac{1}{\\epsilon^2} \\log \\epsilon^2 w \\log w)$ space. Second, we consider an out-of-order strea...
Online Sensor Fault Detection Based on an Improved Strong Tracking Filter
Wang, Lijuan; Wu, Lifeng; Guan, Yong; Wang, Guohui
2015-01-01
We propose a method for online sensor fault detection that is based on the evolving Strong Tracking Filter (STCKF). The cubature rule is used to estimate states to improve the accuracy of making estimates in a nonlinear case. A residual is the difference in value between an estimated value and the true value. A residual will be regarded as a signal that includes fault information. The threshold is set at a reasonable level, and will be compared with residuals to determine whether or not the sensor is faulty. The proposed method requires only a nominal plant model and uses STCKF to estimate the original state vector. The effectiveness of the algorithm is verified by simulation on a drum-boiler model. PMID:25690553
Directory of Open Access Journals (Sweden)
ALEXANDRU, N. D.
2009-06-01
Full Text Available This paper investigates a novel approach for constructing a family of ISI-free pulses produced by improved Nyquist filters with a transfer characteristic derived from an ideal staircase frequency characteristic using interpolation with sine functions. They equal or outperform some recently proposed pulses in terms of ISI performance in the presence of sampling errors. The results for error probability outperform the 4th degree polynomial pulse for a reasonable number of interpolation intervals. The proposed pulses were also investigated for OFDM use including DVB systems in order to reduce their sensitivity to frequency offset. The results presented in this paper equal those of recently found pulses in terms of intercarrier interference (ICI power.
Directory of Open Access Journals (Sweden)
Henry Pinkard
Full Text Available Live imaging of biological specimens using optical microscopy is limited by tradeoffs between spatial and temporal resolution, depth into intact samples, and phototoxicity. Two-photon laser scanning microscopy (2P-LSM, the gold standard for imaging turbid samples in vivo, has conventionally constructed images with sufficient signal-to-noise ratio (SNR generated by sequential raster scans of the focal plane and temporal integration of the collected signals. Here, we describe spatiotemporal rank filtering, a nonlinear alternative to temporal integration, which makes more efficient use of collected photons by selectively reducing noise in 2P-LSM images during acquisition. This results in much higher SNR while preserving image edges and fine details. Practically, this allows for at least a four fold decrease in collection times, a substantial improvement for time-course imaging in biological systems.
Short term wave forecasting, using digital filters, for improved control of Wave Energy Converters
Energy Technology Data Exchange (ETDEWEB)
Tedd, J.; Frigaard, P. [Department of Civil Engineering, Aalborg University, Aalborg (Denmark)
2007-07-01
This paper presents a Digital Filter method for real time prediction of waves incident upon a Wave Energy device. The method transforms waves measured at a point ahead of the device, to expected waves incident on the device. The relationship between these incident waves and power capture is derived experimentally. Results are shown form measurements taken on the Wave Dragon prototype device, a floating overtopping device situated in Northern Denmark. In this case the method is able to accurately predict the surface elevation at the device 11.2 seconds before the measurement is made. This is sufficient to allow advanced control systems to be developed using this knowledge to significantly improve power capture.
Improved sample filtering method for measuring end-to-end path capacity
Institute of Scientific and Technical Information of China (English)
LI Wen-wei; TANG Jun-long; ZHANG Da-fang; XIE Gao-gang
2007-01-01
By analyzing the effect of cross traffic (CT) enforced on packet delay, an improved path capacity measurement method,pcapminp algorithm, was proposed. With this method, path capacity was measured by filtering probe samples based on measured minimum packet-pair delay. The measurability of minimum packet-pair delay was also analyzed by simulation. The results show that,when comparing with pathrate, ifthe CT load is light, both pcapminp and pathrate have similar accuracy; but in the case of heavy CT load, pcapminp is more accurate than Pathrate. When CT load reaches 90%, pcapminp algorithm has only 5% measurement error,which is 10% lower than that of pathrate algorithm. At any CT load levels, the probe cost of pcapminp algorithm is two magnitudes smaller than that of pathrate, and the measurement duration is one magnitude shorter than that of pathrate algorithm.
Throughput-efficient wireless system and blind detection via improved particle filtering
Institute of Scientific and Technical Information of China (English)
Feng Man; Wu Lenan
2009-01-01
This paper introduces throughput-efficient wireless system based on an extension to binary phase modulations, named extended binary phase shift keying (EBPSK), and the corresponding analysis of power spectra, especially the extension to channel capacity are given. Importantly, a novel sequential estimation and detection approach for this EBPSK system is proposed. The basic idea is to design a probabilistic approximation method for the computation of the maximum a posterior distribution via particle filtering method (PF). Subsequently, a new important function in PF is presented, so that the performance of the detector has a great improvement. Finally, computer simulation illustrates that EBPSK system has very high transmission rate, and also the good performance of the proposed PF detector is demonstrated.
An improved filter-u least mean square vibration control algorithm for aircraft framework.
Huang, Quanzhen; Luo, Jun; Gao, Zhiyuan; Zhu, Xiaojin; Li, Hengyu
2014-09-01
Active vibration control of aerospace vehicle structures is very a hot spot and in which filter-u least mean square (FULMS) algorithm is one of the key methods. But for practical reasons and technical limitations, vibration reference signal extraction is always a difficult problem for FULMS algorithm. To solve the vibration reference signal extraction problem, an improved FULMS vibration control algorithm is proposed in this paper. Reference signal is constructed based on the controller structure and the data in the algorithm process, using a vibration response residual signal extracted directly from the vibration structure. To test the proposed algorithm, an aircraft frame model is built and an experimental platform is constructed. The simulation and experimental results show that the proposed algorithm is more practical with a good vibration suppression performance.
Pinkard, Henry; Corbin, Kaitlin; Krummel, Matthew F
2016-01-01
Live imaging of biological specimens using optical microscopy is limited by tradeoffs between spatial and temporal resolution, depth into intact samples, and phototoxicity. Two-photon laser scanning microscopy (2P-LSM), the gold standard for imaging turbid samples in vivo, has conventionally constructed images with sufficient signal-to-noise ratio (SNR) generated by sequential raster scans of the focal plane and temporal integration of the collected signals. Here, we describe spatiotemporal rank filtering, a nonlinear alternative to temporal integration, which makes more efficient use of collected photons by selectively reducing noise in 2P-LSM images during acquisition. This results in much higher SNR while preserving image edges and fine details. Practically, this allows for at least a four fold decrease in collection times, a substantial improvement for time-course imaging in biological systems.
Pre- and post-processing filters for improvement of blood velocity estimation
DEFF Research Database (Denmark)
Schlaikjer, Malene; Jensen, Jørgen Arendt
2000-01-01
with different signal-to-noise ratios (SNR). The exact extent of the vessel and the true velocities are thereby known. Velocity estimates were obtained by employing Kasai's autocorrelator on the data. The post-processing filter was used on the computed 2D velocity map. An improvement of the RMS error...... velocity in the vessels. Post-processing is beneficial to obtain an image that minimizes the variation, and present the important information to the clinicians. Applying the theory of fluid mechanics introduces restrictions on the variations possible in a flow field. Neighboring estimates in time and space...... should be highly correlated, since transitions should occur smoothly. This idea is the basis of the algorithm developed in this study. From Bayesian image processing theory an a posteriori probability distribution for the velocity field is computed based on constraints on smoothness. An estimate...
An improved filter-u least mean square vibration control algorithm for aircraft framework
Huang, Quanzhen; Luo, Jun; Gao, Zhiyuan; Zhu, Xiaojin; Li, Hengyu
2014-09-01
Active vibration control of aerospace vehicle structures is very a hot spot and in which filter-u least mean square (FULMS) algorithm is one of the key methods. But for practical reasons and technical limitations, vibration reference signal extraction is always a difficult problem for FULMS algorithm. To solve the vibration reference signal extraction problem, an improved FULMS vibration control algorithm is proposed in this paper. Reference signal is constructed based on the controller structure and the data in the algorithm process, using a vibration response residual signal extracted directly from the vibration structure. To test the proposed algorithm, an aircraft frame model is built and an experimental platform is constructed. The simulation and experimental results show that the proposed algorithm is more practical with a good vibration suppression performance.
Improved characterization of slow-moving landslides by means of adaptive NL-InSAR filtering
Albiol, David; Iglesias, Rubén.; Sánchez, Francisco; Duro, Javier
2014-10-01
Advanced remote sensing techniques based on space-borne Synthetic Aperture Radar (SAR) have been developed during the last decade showing their applicability for the monitoring of surface displacements in landslide areas. This paper presents an advanced Persistent Scatterer Interferometry (PSI) processing based on the Stable Point Network (SPN) technique, developed by the company Altamira-Information, for the monitoring of an active slowmoving landslide in the mountainous environment of El Portalet, Central Spanish Pyrenees. For this purpose, two TerraSAR-X data sets acquired in ascending mode corresponding to the period from April to November 2011, and from August to November 2013, respectively, are employed. The objective of this work is twofold. On the one hand, the benefits of employing Nonlocal Interferomtric SAR (NL-InSAR) adaptive filtering techniques over vegetated scenarios to maximize the chances of detecting natural distributed scatterers, such as bare or rocky areas, and deterministic point-like scatterers, such as man-made structures or poles, is put forward. In this context, the final PSI displacement maps retrieved with the proposed filtering technique are compared in terms of pixels' density and quality with classical PSI, showing a significant improvement. On the other hand, since SAR systems are only sensitive to detect displacements in the line-of-sight (LOS) direction, the importance of projecting the PSI displacement results retrieved along the steepest gradient of the terrain slope is discussed. The improvements presented in this paper are particularly interesting in these type of applications since they clearly allow to better determine the extension and dynamics of complex landslide phenomena.
Weak monotonicity inequality and partial regularity for harmonic maps
Institute of Scientific and Technical Information of China (English)
沈尧天; 严树森
1999-01-01
The notion of locally weak monotonicity inequality for weakly harmonic maps is introduced and various results on this class of maps are obtained. For example, the locally weak monotonicity inequality is nearly equivalent to the ε-regularity.
Monotonic Loading of Circular Surface Footings on Clay
DEFF Research Database (Denmark)
Ibsen, Lars Bo; Barari, Amin
2011-01-01
Appropriate modeling of offshore foundations under monotonic loading is a significant challenge in geotechnical engineering. This paper reports experimental and numerical analyses, specifically investigating the response of circular surface footings during monotonic loading and elastoplastic beha...
Directory of Open Access Journals (Sweden)
Wilmar HernÃƒÂ¡ndez
2001-06-01
Full Text Available In this paper a Kalman filter is used to cancel noise and interference contained in two accelerometers embedded in a car under performance tests. Here, the frequency bands of the signals of interest and their noise (deterministic as well as stochastic are not strongly mixed with each other but it is very difficult to diminish the noise by using the classical approach to filtering. This reason, among others, justifies the necessity of the application of optimal filtering; and the Kalman filtering application allowed us to obtain optimal results (in the minimum mean-square sense and signal-to-noise ratio improvements higher than 30 dB were achieved. The experimental results demonstrate the importance of using both analog signal conditioning and digital signal processing when dealing with signals corrupted by noise.
A-monotonicity and applications to nonlinear variational inclusion problems
Directory of Open Access Journals (Sweden)
Ram U. Verma
2004-01-01
Full Text Available A new notion of the A-monotonicity is introduced, which generalizes the H-monotonicity. Since the A-monotonicity originates from hemivariational inequalities, and hemivariational inequalities are connected with nonconvex energy functions, it turns out to be a useful tool proving the existence of solutions of nonconvex constrained problems as well.
On the strong monotonicity of the CABARET scheme
Ostapenko, V. V.
2012-03-01
The strong monotonicity of the CABARET scheme with single flux correction is analyzed as applied to the linear advection equation. It is shown that the scheme is strongly monotone (has the NED property) at Courant numbers r ∈ (0,0,5), for which it is monotone. Test computations illustrating this property of the CABARET scheme are presented.
Testing Manifest Monotonicity Using Order-Constrained Statistical Inference
Tijmstra, Jesper; Hessen, David J.; van der Heijden, Peter G. M.; Sijtsma, Klaas
2013-01-01
Most dichotomous item response models share the assumption of latent monotonicity, which states that the probability of a positive response to an item is a nondecreasing function of a latent variable intended to be measured. Latent monotonicity cannot be evaluated directly, but it implies manifest monotonicity across a variety of observed scores,…
Improving visibility of X-ray phase-contrast imaging with Wiener filtering.
Gong, Shaorun; Gao, Feng; Zhou, Zhongxing
2010-01-01
To investigate the degrading effects of the physical parameters on the in-line X-ray phase-contrast imaging (XPCi), a simulation tool based on the Fresnel/Kirchhoff diffraction integral was firstly developed with comprehensively considering effects of the source-to-sample (S-S) and sample-to-detector (S-D) distances, the practical characteristics of a polychromatic and finite size source, the point spread function (PSF) of the fluorescent screen and the spatial resolution of the detector on the theoretical phase-contrast pattern. By a comparison between the simulative profile and the experimental one under the commonly-used parameters, an acceptable consistency has been demonstrated in despite of the deviation between the theoretically-predicted contrast (0.188) and the original experimental one (0.12). From the simulations, it is apparently observed that the fine interference pattern has been severely degraded by the finite spatial resolution, and will inevitably be further deteriorated by the system noise in practice. Since the image quality of the X-ray phase-contrast imaging is strongly dependent on the physical parameters of the system, a model-based deblurring procedure to upgrade the image visibility is preferably desired. As a simple restoration way, a Wiener filter was then introduced to offer an optimal tradeoff between the contrast preservation and the noise suppression. Finally, to minimize the deviation resulting from the finite spatial resolution, one-dimensional interpolation was performed by positioning the set square at a tiny angle to the vertical direction. The result after the Wiener-filtering-based deblurring has shown a considerably improved profile visibility: the processed experimental contrast (0.156) increased by 30% as compared to the original one (0.12) in company with the increase in the signal-to-noise ratio (SNR) by 0.9dB. With the trend of the post-filtered experimental contrast to the theoretical one, it could be motivated that
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...
Improving accuracy in the MPM method using a null space filter
Gritton, Chris; Berzins, Martin
2017-01-01
The material point method (MPM) has been very successful in providing solutions to many challenging problems involving large deformations. Nevertheless there are some important issues that remain to be resolved with regard to its analysis. One key challenge applies to both MPM and particle-in-cell (PIC) methods and arises from the difference between the number of particles and the number of the nodal grid points to which the particles are mapped. This difference between the number of particles and the number of grid points gives rise to a non-trivial null space of the linear operator that maps particle values onto nodal grid point values. In other words, there are non-zero particle values that when mapped to the grid point nodes result in a zero value there. Moreover, when the nodal values at the grid points are mapped back to particles, part of those particle values may be in that same null space. Given positive mapping weights from particles to nodes such null space values are oscillatory in nature. While this problem has been observed almost since the beginning of PIC methods there are still elements of it that are problematical today as well as methods that transcend it. The null space may be viewed as being connected to the ringing instability identified by Brackbill for PIC methods. It will be shown that it is possible to remove these null space values from the solution using a null space filter. This filter improves the accuracy of the MPM methods using an approach that is based upon a local singular value decomposition (SVD) calculation. This local SVD approach is compared against the global SVD approach previously considered by the authors and to a recent MPM method by Zhang and colleagues.
Improvement of S/N ratio of seismic data by hyperbolic filter algorithm
Institute of Scientific and Technical Information of China (English)
Xue Hao; Yue Li; Baojun Yang
2006-01-01
This paper deals with the implementation of the hyperbolic filter algorithm for noise suppression of seismic data. Known the velocity of reflection event, utilizes the resemblance of reflection signal in each seismic trace, the hyperbolic filter algorithm is effective in enhance reflection event and suppress the random noise. This algorithm is used to CDP gathers also is compared with the algorithm of τ-p transform. Simulation shows the hyperbolic filter is effective and better than τ-p transform.
Intrinsic low pass filtering improves signal-to-noise ratio in critical-point flexure biosensors
Energy Technology Data Exchange (ETDEWEB)
Jain, Ankit; Alam, Muhammad Ashraful, E-mail: alam@purdue.edu [School of ECE, Purdue University, West Lafayette, Indiana 47906 (United States)
2014-08-25
A flexure biosensor consists of a suspended beam and a fixed bottom electrode. The adsorption of the target biomolecules on the beam changes its stiffness and results in change of beam's deflection. It is now well established that the sensitivity of sensor is maximized close to the pull-in instability point, where effective stiffness of the beam vanishes. The question: “Do the signal-to-noise ratio (SNR) and the limit-of-detection (LOD) also improve close to the instability point?”, however remains unanswered. In this article, we systematically analyze the noise response to evaluate SNR and establish LOD of critical-point flexure sensors. We find that a flexure sensor acts like an effective low pass filter close to the instability point due to its relatively small resonance frequency, and rejects high frequency noise, leading to improved SNR and LOD. We believe that our conclusions should establish the uniqueness and the technological relevance of critical-point biosensors.
Wehrl entropy, Lieb conjecture and entanglement monotones
Mintert, F; Mintert, Florian; Zyczkowski, Karol
2004-01-01
We propose to quantify the entanglement of pure states of $N \\times N$ bipartite quantum system by defining its Husimi distribution with respect to $SU(N)\\times SU(N)$ coherent states. The Wehrl entropy is minimal if and only if the pure state analyzed is separable. The excess of the Wehrl entropy is shown to be equal to the subentropy of the mixed state obtained by partial trace of the bipartite pure state. This quantity, as well as the generalized (R{\\'e}nyi) subentropies, are proved to be Schur--convex, so they are entanglement monotones and may be used as alternative measures of entanglement.
Improved High-Rejection Filters and MEMS-Enabled Smart Reconfigurable Antennas Project
National Aeronautics and Space Administration — Proposed work envisions development of high-rejection filters and smart reconfigurable antennas using MEMS switches. Adaptive feature of the proposed antenna...
The particulate filter wants to improve; Le filtre a particules veut se perfectionner
Energy Technology Data Exchange (ETDEWEB)
Beaufils, Ph.
2003-11-01
Several car makers, in particular the German ones, have adopted a particulate filter technology with catalyst impregnation, a priori more simple than the one with additive proposed since more than three years now by the PSA group, leader and pioneer in this domain. However, the regeneration is less efficient with the impregnation-type filter and requires a greater fuel over-consumption (4 to 6 %) than with the additive-type filter (1 to 2%). The durability and reliability of the impregnation-type filter is also inferior. According to PSA, the impregnation-type technology will require 4 more years of development to become effective. (J.S.)
Energy Technology Data Exchange (ETDEWEB)
Goyal, Nimit, E-mail: nimitgoyal@doctors.org.u [University Hospital of Wales, Heath Park, Cardiff, CF14 4XW (United Kingdom); Rachapalli, Vamsidhar; Burns, Helen; Lloyd, David C.F. [University Hospital of Wales, Heath Park, Cardiff, CF14 4XW (United Kingdom)
2011-02-15
Purpose: To evaluate the usefulness of filter and anti-scatter grid combination in demonstrating the cervicothoracic junction in lateral cervical spine radiographs performed for trauma patients. Methods: Following a change in departmental protocol in our hospital, anti-scatter grid and filter are routinely used for lateral cervical spine radiograph in all trauma patients with immobilised cervical spine. A retrospective study was done to compare the efficacy of lateral cervical spine radiographs in demonstrating the cervicothoracic junction for a period of three months before and after the implementation of the change. All images were independently evaluated by two observers. Results: 253 trauma patients had a lateral cervical spine radiograph done in January to March 2003 without using the anti-scatter grid and filter while 309 patients in January to March 2007, using filter and grid. Inter-observer variability between the two observers was calculated using Cohen's Kappa which showed good and very good agreement for 2003 and 2007 respectively. 126 (49.8%) images adequately demonstrated the cervicothoracic junction without using filter and grid while 189 (61.1%) were adequate following their use. This was statistically significant (Fischer exact test, p value = 0.0081). Conclusion: The use of filter and anti-scatter grids improves the visualisation of cervicothoracic junction in lateral cervical spine imaging and reduces the need to repeat exposure.
Wang, Xuemei; Ni, Wenbo
2016-09-01
For loosely coupled INS/GPS integrated navigation systems with low-cost and low-accuracy microelectromechanical device inertial sensors, in order to obtain enough accuracy, a full-state nonlinear dynamic model rather than a linearized error model is much more preferable. Particle filters are particularly for nonlinear and non-Gaussian situations, but typical bootstrap particle filters (BPFs) and some improved particle filters (IPFs) such as auxiliary particle filters (APFs) and Gaussian particle filters (GPFs) cannot solve the mismatch between the importance function and the likelihood function very well. The predicted particles propagated through inertial navigation equations cannot be scattered with certainty within the effective range of current observation when there are large drift errors of the inertial sensors. Therefore, the current observation cannot play the correction role well and these particle filters are invalid to some extent. The proposed IPF firstly estimates the corresponding state bias errors according to the current observation and then corrects the bias errors of the predicted particles before determining the weights and resampling the particles. Simulations and practical experiments both show that the proposed IPF can effectively solve the mismatch between the importance function and the likelihood function of a BPF and compensate the accumulated errors of INSs very well. It has great robustness in a serious noisy scenario.
Topological recursion and a quantum curve for monotone Hurwitz numbers
Do, Norman; Dyer, Alastair; Mathews, Daniel V.
2017-10-01
Classical Hurwitz numbers count branched covers of the Riemann sphere with prescribed ramification data, or equivalently, factorisations in the symmetric group with prescribed cycle structure data. Monotone Hurwitz numbers restrict the enumeration by imposing a further monotonicity condition on such factorisations. In this paper, we prove that monotone Hurwitz numbers arise from the topological recursion of Eynard and Orantin applied to a particular spectral curve. We furthermore derive a quantum curve for monotone Hurwitz numbers. These results extend the collection of enumerative problems known to be governed by the paradigm of topological recursion and quantum curves, as well as the list of analogues between monotone Hurwitz numbers and their classical counterparts.
Design of a Low-Voltage High-Speed Switched-Capacitor Filters Using Improved Auto Zeroed Integrator
Rashtian, M.; Hashemipour, O.; Navi, K.
The low-voltage high-speed auto zeroed integrator characteristics is improved by applying current steering mechanism in the opamp structure of the integrators and utilizing the non-linear properties of switches. The proposed design results in considerable reduction of power dissipation. Based on this improvement a band-pass filter with centre frequency of 1 MHz and clock frequency of 6 MHz is designed. Furthermore a new circuit for implementation of an auto-zero low-pass filter is presented. Based on this configuration a fourth order low-pass switched capacitor filter with cut off frequency of 600 KHz and clock frequency of 6 MHz is presented. The proposed circuits are simulated using HSPICE and 0.25 μm CMOS technology at 1.5 V supply voltage.
The Monotonicity Puzzle: An Experimental Investigation of Incentive Structures
Directory of Open Access Journals (Sweden)
Jeannette Brosig
2010-05-01
Full Text Available Non-monotone incentive structures, which - according to theory - are able to induce optimal behavior, are often regarded as empirically less relevant for labor relationships. We compare the performance of a theoretically optimal non-monotone contract with a monotone one under controlled laboratory conditions. Implementing some features relevant to real-world employment relationships, our paper demonstrates that, in fact, the frequency of income-maximizing decisions made by agents is higher under the monotone contract. Although this observed behavior does not change the superiority of the non-monotone contract for principals, they do not choose this contract type in a significant way. This is what we call the monotonicity puzzle. Detailed investigations of decisions provide a clue for solving the puzzle and a possible explanation for the popularity of monotone contracts.
An Improved WiFi/PDR Integrated System Using an Adaptive and Robust Filter for Indoor Localization
Directory of Open Access Journals (Sweden)
Zengke Li
2016-11-01
Full Text Available Location-based services (LBS are services offered through a mobile device that take into account a device’s geographical location. To provide position information for these services, location is a key process. GNSS (Global Navigation Satellite System can provide sub-meter accuracy in open-sky areas using satellite signals. However, for indoor and dense urban environments, the accuracy deteriorates significantly because of weak signals and dense multipaths. The situation becomes worse in indoor environments where the GNSS signals are unreliable or totally blocked. To improve the accuracy of indoor positioning for location-based services, an improved WiFi/Pedestrian Dead Reckoning (PDR integrated positioning and navigation system using an adaptive and robust filter is presented. The adaptive filter is based on scenario and motion state recognition and the robust filter is based on the Mahalanobis distance. They are combined and used in the WiFi/PDR integrated system to weaken the effect of gross errors on the dynamic and observation models. To validate their performance in the WiFi/PDR integrated system, a real indoor localization experiment is conducted. The results indicate that the adaptive filter is better able to adapt to the circumstances of the dynamic model by adjusting the covariance of the process noise and the robust Kalman filter is able to mitigate the harmful effect of gross errors from the WiFi positioning.
Hu, Zhiyang; Xu, Shuhong; Xu, Xiaojing; Wang, Zhaochong; Wang, Zhuyuan; Wang, Chunlei; Cui, Yiping
2015-10-08
In optics, when polychromatic light is filtered by an optical filter, the monochromaticity of the light can be improved. In this work, we reported that Ag dopant atoms could be used as an optical filter for nanosized Mn:ZnSe quantum dots (QDs). If no Ag doping, aqueous Mn:ZnSe QDs have low monochromaticity due to coexisting of strong ZnSe band gap emission, ZnSe trap emission, and Mn dopant emission. After doping of Ag into QDs, ZnSe band gap and ZnSe trap emissions can be filtered, leaving only Mn dopant emission with improved monochromaticity. The mechanism for the optical filtering effect of Ag was investigated. The results indicate that the doping of Ag will introduce a new faster deactivation process from ZnSe conduction band to Ag energy level, leading to less electrons deactived via ZnSe band gap emission and ZnSe trap emission. As a result, only Mn dopant emission is left.
A Method to improve line flux and redshift measurements with narrowband filters
Zabl, J; Møller, P; Milvang-Jensen, B; Nilsson, K K; Fynbo, J P U; Fèvre, O Le; Tasca, L A M
2016-01-01
High redshift star-forming galaxies are discovered routinely through a flux excess in narrowband filters (NB) caused by an emission line. In most cases, the width of such filters is broad compared to typical line widths, and the throughput of the filters varies substantially within the bandpass. This leads to substantial uncertainties in redshifts and fluxes that are derived from the observations with one specific NB. In this work we demonstrate that the uncertainty in measured line parameters can be sharply reduced by using repeated observations of the same target field with filters that have slightly different transmittance curves. Such data are routinely collected with some large field imaging cameras that use multiple detectors and a separate filter for each of the detectors. An example is the NB118 data from ESO's VISTA InfraRed CAMera (VIRCAM). We carefully developed and characterized this method to determine more accurate redshift and line flux estimates from the ratio of apparent fluxes measured from ...
Highway traffic estimation of improved precision using the derivative-free nonlinear Kalman Filter
Rigatos, Gerasimos; Siano, Pierluigi; Zervos, Nikolaos; Melkikh, Alexey
2015-12-01
The paper proves that the PDE dynamic model of the highway traffic is a differentially flat one and by applying spatial discretization its shows that the model's transformation into an equivalent linear canonical state-space form is possible. For the latter representation of the traffic's dynamics, state estimation is performed with the use of the Derivative-free nonlinear Kalman Filter. The proposed filter consists of the Kalman Filter recursion applied on the transformed state-space model of the highway traffic. Moreover, it makes use of an inverse transformation, based again on differential flatness theory which enables to obtain estimates of the state variables of the initial nonlinear PDE model. By avoiding approximate linearizations and the truncation of nonlinear terms from the PDE model of the traffic's dynamics the proposed filtering methods outperforms, in terms of accuracy, other nonlinear estimators such as the Extended Kalman Filter. The article's theoretical findings are confirmed through simulation experiments.
Improved fission neutron energy discrimination with 4He detectors through pulse filtering
Zhu, Ting; Liang, Yinong; Rolison, Lucas; Barker, Cathleen; Lewis, Jason; Gokhale, Sasmit; Chandra, Rico; Kiff, Scott; Chung, Heejun; Ray, Heather; Baciak, James E.; Enqvist, Andreas; Jordan, Kelly A.
2017-03-01
This paper presents experimental and computational techniques implemented for 4He gas scintillation detectors for induced fission neutron detection. Fission neutrons are produced when natural uranium samples are actively interrogated by 2.45 MeV deuterium-deuterium fusion reaction neutrons. Fission neutrons of energies greater than 2.45 MeV can be distinguished by their different scintillation pulse height spectra since 4He detectors retain incident fast neutron energy information. To enable the preferential detection of fast neutrons up to 10 MeV and suppress low-energy event counts, the detector photomultiplier gain is lowered and trigger threshold is increased. Pile-up and other unreliable events due to the interrogating neutron flux and background radiation are filtered out prior to the evaluation of pulse height spectra. With these problem-specific calibrations and data processing, the 4He detector's accuracy at discriminating fission neutrons up to 10 MeV is improved and verified with 252Cf spontaneous fission neutrons. Given the 4He detector's ability to differentiate fast neutron sources, this proof-of-concept active-interrogation measurement demonstrates the potential of special nuclear materials detection using a 4He fast neutron detection system.
Junqueira, Magno; Spirin, Victor; Balbuena, Tiago Santana; Waridel, Patrice; Surendranath, Vineeth; Kryukov, Grigoriy; Adzhubei, Ivan; Thomas, Henrik; Sunyaev, Shamil; Shevchenko, Andrej
2009-01-01
Only a small fraction of spectra acquired in LC-MS/MS runs matches peptides from target proteins upon database searches. The remaining, operationally termed background, spectra originate from a variety of poorly controlled sources and affect the throughput and confidence of database searches. Here, we report an algorithm and its software implementation that rapidly removes background spectra, regardless of their precise origin. The method estimates the dissimilarity distance between screened MS/MS spectra and unannotated spectra from a partially redundant background library compiled from several control and blank runs. Filtering MS/MS queries enhanced the protein identification capacity when searches lacked spectrum to sequence matching specificity. In sequence-similarity searches it reduced by, on average, 30-fold the number of orphan hits, which were not explicitly related to background protein contaminants and required manual validation. Removing high quality background MS/MS spectra, while preserving in the data set the genuine spectra from target proteins, decreased the false positive rate of stringent database searches and improved the identification of low-abundance proteins. PMID:18558732
Institute of Scientific and Technical Information of China (English)
ZHUANG You-Yi; ZHANG Yao-Ju
2009-01-01
A new design is presented to improve the magnetic recording density in all-optical magnetic storage.By using the high numerical lens with a high-pass angular spectrum filter, circularly polarized laser pulses are focused into the magneto-optic film with the perpendicular anisotropy.Magnetization of the film is induced by the inverse Faraday effect.As the obstructed angle of the filter increases the magnetic recording density increases evidently.The magnetization intensity and the sidelobe effect are also discussed.
Institute of Scientific and Technical Information of China (English)
柳林; 江利明; 李洪忠
2016-01-01
The scattering-model-based (SMB) speckle filtering for polarimetric SAR (PolSAR) data is reasonably effective in preserving dominant scattering mechanisms. However, the efficiency strongly depends on the accuracies of both the decomposition and classification of the scattering properties. In addition, a relatively weak speckle reduction particularly in distributed media was reported in the related literatures. In this work, an improved SMB filtering strategy is proposed considering the aforementioned deficiencies. First, the orientation angle compensation is incorporated into the SMB filtering process to remedy the overestimation of the volume scattering contribution in the Freeman-Durden decomposition. In addition, an algorithm to select the homogenous pixels is developed based on the spatial majority rule for adaptive speckle reduction. We demonstrate the superiority of the proposed methods in terms of scattering property preservation and speckle noise reduction using L-band PolSAR data sets of San Francisco that were acquired by the NASA/JPL airborne SAR (AIRSAR) system.
Convex functions, monotone operators and differentiability
Phelps, Robert R
1989-01-01
These notes start with an introduction to the differentiability of convex functions on Banach spaces, leading to the study of Asplund spaces and their intriguing relationship to monotone operators (and more general set-values maps) and Banach spaces with the Radon-Nikodym property. While much of this is classical, some of it is presented using streamlined proofs which were not available until recently. Considerable attention is paid to contemporary results on variational principles and perturbed optimization in Banach spaces, exhibiting their close connections with Asplund spaces. An introductory course in functional analysis is adequate background for reading these notes which can serve as the basis for a seminar of a one-term graduate course. There are numerous excercises, many of which form an integral part of the exposition.
Generalized convexity, generalized monotonicity recent results
Martinez-Legaz, Juan-Enrique; Volle, Michel
1998-01-01
A function is convex if its epigraph is convex. This geometrical structure has very strong implications in terms of continuity and differentiability. Separation theorems lead to optimality conditions and duality for convex problems. A function is quasiconvex if its lower level sets are convex. Here again, the geo metrical structure of the level sets implies some continuity and differentiability properties for quasiconvex functions. Optimality conditions and duality can be derived for optimization problems involving such functions as well. Over a period of about fifty years, quasiconvex and other generalized convex functions have been considered in a variety of fields including economies, man agement science, engineering, probability and applied sciences in accordance with the need of particular applications. During the last twenty-five years, an increase of research activities in this field has been witnessed. More recently generalized monotonicity of maps has been studied. It relates to generalized conve...
Improving the performance of the prony method using a wavelet domain filter for MRI denoising.
Jaramillo, Rodney; Lentini, Marianela; Paluszny, Marco
2014-01-01
The Prony methods are used for exponential fitting. We use a variant of the Prony method for abnormal brain tissue detection in sequences of T 2 weighted magnetic resonance images. Here, MR images are considered to be affected only by Rician noise, and a new wavelet domain bilateral filtering process is implemented to reduce the noise in the images. This filter is a modification of Kazubek's algorithm and we use synthetic images to show the ability of the new procedure to suppress noise and compare its performance with respect to the original filter, using quantitative and qualitative criteria. The tissue classification process is illustrated using a real sequence of T 2 MR images, and the filter is applied to each image before using the variant of the Prony method.
Improving the Performance of the Prony Method Using a Wavelet Domain Filter for MRI Denoising
Directory of Open Access Journals (Sweden)
Rodney Jaramillo
2014-01-01
Full Text Available The Prony methods are used for exponential fitting. We use a variant of the Prony method for abnormal brain tissue detection in sequences of T2 weighted magnetic resonance images. Here, MR images are considered to be affected only by Rician noise, and a new wavelet domain bilateral filtering process is implemented to reduce the noise in the images. This filter is a modification of Kazubek’s algorithm and we use synthetic images to show the ability of the new procedure to suppress noise and compare its performance with respect to the original filter, using quantitative and qualitative criteria. The tissue classification process is illustrated using a real sequence of T2 MR images, and the filter is applied to each image before using the variant of the Prony method.
Color reproductivity improvement with additional virtual color filters for WRGB image sensor
Kawada, Shun; Kuroda, Rihito; Sugawa, Shigetoshi
2013-02-01
We have developed a high accuracy color reproduction method based on an estimated spectral reflectance of objects using additional virtual color filters for a wide dynamic range WRGB color filter CMOS image sensor. The four virtual color filters are created by multiplying the spectral sensitivity of White pixel by gauss functions which have different central wave length and standard deviation, and the virtual sensor outputs of those virtual filters are estimated from the four real output signals of the WRGB image sensor. The accuracy of color reproduction was evaluated with a Macbeth Color Checker (MCC), and the averaged value of the color difference ΔEab of 24 colors was 1.88 with our approach.
THE EFFICIENCY OF YARN WOUND FILTERS IN GIARDIA CYSTS REMOVAL USING THE IMPROVED SUCROSE GRADIENT
Directory of Open Access Journals (Sweden)
M.R SHAH MANSOURI
2001-09-01
Full Text Available Introduction. The protozoan parasite Giardia is one of the important biological cotaminants in water. lts presence in water has caused the outbreak of a number of epidemics in various part of the world including the United States. The major impediment in detecting this particular parasite is unavailability of suitable filters capable of removing it from water. Regarding the fact yarn wound filters (cartridge used in removing Giardia under laboratory condition are currently difficult to obtain in Iran, attempts were made to design and manufacture the filters according to standards recommended in the literature. Methods. To determine the efficiency of filters manufactured in this way, a pilot system was established and parameters of concern were investigated. A given number of cysts were introduced in each case to the water in the pilot tank after being counted on the hemocytometer lamella After the entire tank water (at least 4001had been pumped through the filters, the filter were removed from the pilot system to have their yarns separated and washed. The cysts recovered were then counted and compared with the original input cysts to determine the efficiency of the filters. Formation of sediments on filters due to suspended solids in water was a great impediment in counting the cysts hidden in the sediments. To overcome this difficulty, the method of floatation in sucrose was used to remove the hidden cysts from the sediments. Regarding the morphological characteristics of the cysts, the method was also studied in terms of the sucrose film concentration and the effects of centrifugal speed and duration on the removal of cysts from sediments. Results. The results indicated an efficiency of 80.69±5.85, which was ideal for a first experience in Iran. a level of 2.5 molar of Sucrose with a duration of 10 minutes for the centrifugation time at 2,000 rpm were considered to be optimum levels to yield a certainty of 95 percent and an efficiency of
Improving retouched Bloom filter for trading off selected false positives against false negatives
Donnet, Benoît; Baynat, Bruno; Friedman, Timur
2010-01-01
Where distributed agents must share voluminous set membership information, Bloom fil- ters provide a compact, though lossy, way for them to do so. Numerous recent networking papers have examined the trade-offs between the bandwidth consumed by the transmis- sion of Bloom filters, and the error rate, which takes the form of false positives. This paper is about the retouched Bloom filter (RBF). An RBF is an extension that makes the Bloom fil- ter more flexible by permitting the removal of false...
Analog filtering of large solvent signals for improved dynamic range in high-resolution NMR.
Redfield, A G; Kunz, S D
1998-01-01
The large solvent signal from samples in H2O solvent still challenges the dynamic range capability of any spectrometer. The solvent signal can be largely removed with a pair of simple resistor-capacitor (RC) high-pass filters when the solvent frequency is set at center band (zero frequency) using quadrature detection, with RC approximately 0.5 ms. However, an approximately 0.5-ms transient remains at initial time, which we reduce fourfold for a short time only, just before the A/D converter, by means of a variable-gain amplifier, and later restore with software. This modification can result in a nearly fourfold increase in dynamic range. When we converted to a frequency-shifted mode (A. G. Redfield and S. D. Kunz, 1994, J. Magn. Reson. A 108, 234-237) we replaced the RC high-pass filter with a quadrature feedback notch filter tuned to the solvent frequency (5.06 kHz). This filter is an example of a class of two-input/two-output filters which maintain the spectral integrity (image-free character) of quadrature signals. Digital filters of the same type are also considered briefly. We discuss the implications of these ideas for spectrometer input design, including schemes for elimination of radiation damping, and effects of probe bandwidth on extreme oversampling.
Sun, Jin; Xu, Xiaosu; Liu, Yiting; Zhang, Tao; Li, Yao
2016-07-12
In order to reduce the influence of fiber optic gyroscope (FOG) random drift error on inertial navigation systems, an improved auto regressive (AR) model is put forward in this paper. First, based on real-time observations at each restart of the gyroscope, the model of FOG random drift can be established online. In the improved AR model, the FOG measured signal is employed instead of the zero mean signals. Then, the modified Sage-Husa adaptive Kalman filter (SHAKF) is introduced, which can directly carry out real-time filtering on the FOG signals. Finally, static and dynamic experiments are done to verify the effectiveness. The filtering results are analyzed with Allan variance. The analysis results show that the improved AR model has high fitting accuracy and strong adaptability, and the minimum fitting accuracy of single noise is 93.2%. Based on the improved AR(3) model, the denoising method of SHAKF is more effective than traditional methods, and its effect is better than 30%. The random drift error of FOG is reduced effectively, and the precision of the FOG is improved.
Directory of Open Access Journals (Sweden)
Zhiyong Lv
2016-12-01
Full Text Available Land cover classification using very high spatial resolution (VHSR imaging plays a very important role in remote sensing applications. However, image noise usually reduces the classification accuracy of VHSR images. Image spatial filters have been recently adopted to improve VHSR image land cover classification. In this study, a new object-based image filter using topology and feature constraints is proposed, where an object is considered as a central object and has irregular shapes and various numbers of neighbors depending on the nature of the surroundings. First, multi-scale segmentation is used to generate a homogeneous image object and extract the corresponding vectors. Then, topology and feature constraints are proposed to select the adjacent objects, which present similar materials to the central object. Third, the feature of the central object is smoothed by the average of the selected objects’ feature. This proposed approach is validated on three VHSR images, ranging from a fixed-wing aerial image to UAV images. The performance of the proposed approach is compared to a standard object-based approach (OO, object correlative index (OCI spatial feature based method, a recursive filter (RF, and a rolling guided filter (RGF, and has shown a 6%–18% improvement in overall accuracy.
Improvement of self-cleaning type air filter%自洁式空气过滤器的改进
Institute of Scientific and Technical Information of China (English)
王鹏
2012-01-01
The self-cleaning type air filter is fitted before air inlet pipe of air compressor completed for air separation plant. The domestic-made carriage has low service life, and in case of highly wet air the filter paper is liable to stick, which lowers the filtering efficiency, results in frequent repair of air compressor repair, and seriously impairs prolonged stable run of air separation plant. The service life of carriage of self-cleaning type air filter is extended and the filtering efficiency is improved through use of the non-woven filtering cotton blended with compound fiber, the carriage made of compound fiber, and the imported filter paper, adjustment of its programmable controller, and change of its back-blowing pressure and air supply. Here, the work principle of self- cleaning type air filter is briefed, the problems during its operation process are analyzed, and the implementation process and economic benefits of the improvement measures are described.%空分设备配套空压机进气管前设置自洁式空气过滤器，由于国内生产的滤筒使用寿命短，遇含湿量大的空气时滤纸易黏连，进而影响过滤效率，导致空压机检修频繁，严重影响了空分设备长周期稳定运行。通过增加复合纤维无纺滤棉，选用复合纤维滤筒和进口滤纸，调整自洁式空气过滤器的编程控制仪，以及改变反吹压力和反吹气源，达到延长自洁式空气过滤器的滤筒寿命和提高过滤效率的目的。简述自洁式空气过滤器的工作原理，分析其使用过程中存在的问题，阐述改进措施的实施过程及取得的经济效益。
Stability of dynamical systems on the role of monotonic and non-monotonic Lyapunov functions
Michel, Anthony N; Liu, Derong
2015-01-01
The second edition of this textbook provides a single source for the analysis of system models represented by continuous-time and discrete-time, finite-dimensional and infinite-dimensional, and continuous and discontinuous dynamical systems. For these system models, it presents results which comprise the classical Lyapunov stability theory involving monotonic Lyapunov functions, as well as corresponding contemporary stability results involving non-monotonicLyapunov functions.Specific examples from several diverse areas are given to demonstrate the applicability of the developed theory to many important classes of systems, including digital control systems, nonlinear regulator systems, pulse-width-modulated feedback control systems, and artificial neural networks. The authors cover the following four general topics: - Representation and modeling of dynamical systems of the types described above - Presentation of Lyapunov and Lagrange stability theory for dynamical sy...
Stepsize Restrictions for Boundedness and Monotonicity of Multistep Methods
Hundsdorfer, W.
2011-04-29
In this paper nonlinear monotonicity and boundedness properties are analyzed for linear multistep methods. We focus on methods which satisfy a weaker boundedness condition than strict monotonicity for arbitrary starting values. In this way, many linear multistep methods of practical interest are included in the theory. Moreover, it will be shown that for such methods monotonicity can still be valid with suitable Runge-Kutta starting procedures. Restrictions on the stepsizes are derived that are not only sufficient but also necessary for these boundedness and monotonicity properties. © 2011 Springer Science+Business Media, LLC.
On the monotonicity of multidimensional finite difference schemes
Kovyrkina, O.; Ostapenko, V.
2016-10-01
The classical concept of monotonicity, introduced by Godunov for linear one-dimensional difference schemes, is extended to multidimensional case. Necessary and sufficient conditions of monotonicity are obtained for linear multidimensional difference schemes of first order. The constraints on the numerical viscosity are given that ensure the monotonicity of a difference scheme in the multidimensional case. It is proposed a modification of the second order multidimensional CABARET scheme that preserves the monotonicity of one-dimensional discrete solutions and, as a result, ensures higher smoothness in the computation of multidimensional discontinuous solutions. The results of two-dimensional test computations illustrating the advantages of the modified CABARET scheme are presented.
PPA BASED PREDICTION-CORRECTION METHODS FOR MONOTONE VARIATIONAL INEQUALITIES
Institute of Scientific and Technical Information of China (English)
He Bingsheng; Jiang Jianlin; Qian Maijian; Xu Ya
2005-01-01
In this paper we study the proximal point algorithm (PPA) based predictioncorrection (PC) methods for monotone variational inequalities. Each iteration of these methods consists of a prediction and a correction. The predictors are produced by inexact PPA steps. The new iterates are then updated by a correction using the PPA formula. We present two profit functions which serve two purposes: First we show that the profit functions are tight lower bounds of the improvements obtained in each iteration. Based on this conclusion we obtain the convergence inexactness restrictions for the prediction step. Second we show that the profit functions are quadratically dependent upon the step lengths, thus the optimal step lengths are obtained in the correction step. In the last part of the paper we compare the strengths of different methods based on their inexactness restrictions.
A new non-monotone fitness scaling for genetic algorithm
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The properties of selection operators in the genetic algorithm (GA) are studied in detail. It is indicated that the selection of operations is significant for both improving the general fitness of a population and leading to the schema deceptiveness. The stochastic searching characteristics of GA are compared with those of heuristic methods. The influence of selection operators on the GA' s exploration and exploitation is discussed, and the performance of selection operators is evaluated with the premature convergence of the GA taken as an example based on One-Max function. In order to overcome the schema deceptiveness of the GA, a new type of fitness scaling, non monotone scaling, is advanced to enhance the evolutionary ability of a population. The effectiveness of the new scaling method is tested by a trap function and a needle-in-haystack (NiH) function.
Multiple Maneuvering Target Tracking by Improved Particle Filter Based on Multiscan JPDA
Directory of Open Access Journals (Sweden)
Jing Liu
2012-01-01
Full Text Available The multiple maneuvering target tracking algorithm based on a particle filter is addressed. The equivalent-noise approach is adopted, which uses a simple dynamic model consisting of target state and equivalent noise which accounts for the combined effects of the process noise and maneuvers. The equivalent-noise approach converts the problem of maneuvering target tracking to that of state estimation in the presence of nonstationary process noise with unknown statistics. A novel method for identifying the nonstationary process noise is proposed in the particle filter framework. Furthermore, a particle filter based multiscan Joint Probability Data Association (JPDA filter is proposed to deal with the data association problem in a multiple maneuvering target tracking. In the proposed multiscan JPDA algorithm, the distributions of interest are the marginal filtering distributions for each of the targets, and these distributions are approximated with particles. The multiscan JPDA algorithm examines the joint association events in a multiscan sliding window and calculates the marginal posterior probability based on the multiscan joint association events. The proposed algorithm is illustrated via an example involving the tracking of two highly maneuvering, at times closely spaced and crossed, targets, based on resolved measurements.
A Kalman filter implementation for precision improvement in low-cost GPS positioning of tractors.
Gomez-Gil, Jaime; Ruiz-Gonzalez, Ruben; Alonso-Garcia, Sergio; Gomez-Gil, Francisco Javier
2013-11-08
Low-cost GPS receivers provide geodetic positioning information using the NMEA protocol, usually with eight digits for latitude and nine digits for longitude. When these geodetic coordinates are converted into Cartesian coordinates, the positions fit in a quantization grid of some decimeters in size, the dimensions of which vary depending on the point of the terrestrial surface. The aim of this study is to reduce the quantization errors of some low-cost GPS receivers by using a Kalman filter. Kinematic tractor model equations were employed to particularize the filter, which was tuned by applying Monte Carlo techniques to eighteen straight trajectories, to select the covariance matrices that produced the lowest Root Mean Square Error in these trajectories. Filter performance was tested by using straight tractor paths, which were either simulated or real trajectories acquired by a GPS receiver. The results show that the filter can reduce the quantization error in distance by around 43%. Moreover, it reduces the standard deviation of the heading by 75%. Data suggest that the proposed filter can satisfactorily preprocess the low-cost GPS receiver data when used in an assistance guidance GPS system for tractors. It could also be useful to smooth tractor GPS trajectories that are sharpened when the tractor moves over rough terrain.
Institute of Scientific and Technical Information of China (English)
ZHAO Xiao-Feng; LI Cheng-Fang; RUAN Hao
2004-01-01
@@ We present an improved confocal readout system to achieve three-dimensional superresolution. This improved system is based on a combination of two different annular binary phase filters, the one designed for increasing the transverse superresolution and the other for achieving axial superresolution. By adjusting the pupil parameters,each pupil can be well designed. The simulation results show that with this improved system, the area of the central lobe of the three-dimensional point spread function of the read optics is greatly reduced. Moreover, the side-lobes are extinguished.
Improved Computing-Efficiency Least-Squares Algorithm with Application to All-Pass Filter Design
Directory of Open Access Journals (Sweden)
Lo-Chyuan Su
2013-01-01
Full Text Available All-pass filter design can be generally achieved by solving a system of linear equations. The associated matrices involved in the set of linear equations can be further formulated as a Toeplitz-plus-Hankel form such that a matrix inversion is avoided. Consequently, the optimal filter coefficients can be solved by using computationally efficient Levinson algorithms or Cholesky decomposition technique. In this paper, based on trigonometric identities and sampling the frequency band of interest uniformly, the authors proposed closed-form expressions to compute the elements of the Toeplitz-plus-Hankel matrix required in the least-squares design of IIR all-pass filters. Simulation results confirm that the proposed method achieves good performance as well as effectiveness.
Improving the treatment efficiency of constructed wetlands with zeolite-containing filter sands.
Bruch, Ingo; Fritsche, Johannes; Bänninger, Dominik; Alewell, Ulrike; Sendelov, Michael; Hürlimann, Heinz; Hasselbach, Ralf; Alewell, Christine
2011-01-01
In this study the physical and chemical properties of three different lava sands used in constructed wetlands for municipal wastewater treatment were investigated. The aim was to identify those properties and mechanisms that render lava sands as highly efficient filter media which could substitute conventional, fluviatile sands. It was shown that although lava sands per se may be suitable filter materials, the presence of zeolite minerals within the lava sands enhances the purification efficiency tremendously. Zeolites not only increase the sorption capacity, but even more important, they are able to absorb water in large amounts, which in turn leads to stronger swelling. The latter reduces hydrological conductivity considerably, resulting in a longer contact time to eliminate pollutants. A simple mineralogical survey of filter materials for the presence of zeolites may render many installations of constructed wetlands successful. Copyright Â© 2010 Elsevier Ltd. All rights reserved.
Zeng, Bangze; Zhu, Youpan; Li, Zemin; Hu, Dechao; Luo, Lin; Zhao, Deli; Huang, Juan
2014-11-01
Duo to infrared image with low contrast, big noise and unclear visual effect, target is very difficult to observed and identified. This paper presents an improved infrared image detail enhancement algorithm based on adaptive histogram statistical stretching and gradient filtering (AHSS-GF). Based on the fact that the human eyes are very sensitive to the edges and lines, the author proposed to extract the details and textures by using the gradient filtering. New histogram could be acquired by calculating the sum of original histogram based on fixed window. With the minimum value for cut-off point, author carried on histogram statistical stretching. After the proper weights given to the details and background, the detail-enhanced results could be acquired finally. The results indicate image contrast could be improved and the details and textures could be enhanced effectively as well.
Improved H_∞ filtering for Markov jumping linear systems with non-accessible mode information
Institute of Scientific and Technical Information of China (English)
GUO YaFeng; LI ShaoYuan
2009-01-01
This paper is concerned with the H_∞ filtering problems for both continuous-and discrete-time Markov jumping linear systems (MJLS) with non-accessible mode Information.A new design method is proposed,which greatly reduces the overdesign Introduced in the derivation process.The desired filters can be obtained from the solution of convex optimization problems in terms of linear matrix inequalities (LMIs),which can be solved via efficient interior-point algorithms.Numerical examples are provided to Illustrate the advantages of the proposed approach.
DEFF Research Database (Denmark)
Stigaard Laursen, Morten; Jørgensen, Rasmus Nyholm; Midtiby, Henrik
. This method utilizes that most vegetation reflects more green light than blue and red. As silicon based image sensors is also sensitive to near-infrared light a typical rgb-camera will have a filter in place to block the near-infrared light. When using excess green the ideal filter would be a sinc...... diseases, weeds and fungus. A common method for interpretation is based on the leaf shape. However in order to reliably achieve a good description of the shape a good segmentation is required. The excess green index is one of the most common methods for green vegetation segmentation within agriculture...
Pérez-Ortiz, Juan Antonio; Gers, Felix A; Eck, Douglas; Schmidhuber, Jürgen
2003-03-01
The long short-term memory (LSTM) network trained by gradient descent solves difficult problems which traditional recurrent neural networks in general cannot. We have recently observed that the decoupled extended Kalman filter training algorithm allows for even better performance, reducing significantly the number of training steps when compared to the original gradient descent training algorithm. In this paper we present a set of experiments which are unsolvable by classical recurrent networks but which are solved elegantly and robustly and quickly by LSTM combined with Kalman filters.
Tanaka, Kiyotsugu; Choi, Yong Joon; Moriwaki, Yu; Hizawa, Takeshi; Iwata, Tatsuya; Dasai, Fumihiro; Kimura, Yasuyuki; Takahashi, Kazuhiro; Sawada, Kazuaki
2017-04-01
We developed a low-detection-limit filter-free fluorescence sensor by a charge accumulation technique. For charge accumulation, a floating diffusion amplifier (FDA), which included a floating diffusion capacitor, a transfer gate, and a source follower circuit, was used. To integrate CMOS circuits with the filter-free fluorescence sensor, we adopted a triple-well process to isolate transistors from the sensor on a single chip. We detected 0.1 nW fluorescence under the illumination of excitation light by 1.5 ms accumulation, which was one order of magnitude greater than that of a previous current detection sensor.
Monotone measures of ergodicity for Markov chains
Directory of Open Access Journals (Sweden)
J. Keilson
1998-01-01
Full Text Available The following paper, first written in 1974, was never published other than as part of an internal research series. Its lack of publication is unrelated to the merits of the paper and the paper is of current importance by virtue of its relation to the relaxation time. A systematic discussion is provided of the approach of a finite Markov chain to ergodicity by proving the monotonicity of an important set of norms, each measures of egodicity, whether or not time reversibility is present. The paper is of particular interest because the discussion of the relaxation time of a finite Markov chain [2] has only been clean for time reversible chains, a small subset of the chains of interest. This restriction is not present here. Indeed, a new relaxation time quoted quantifies the relaxation time for all finite ergodic chains (cf. the discussion of Q1(t below Equation (1.7]. This relaxation time was developed by Keilson with A. Roy in his thesis [6], yet to be published.
Remarks on a monotone Markov chain
Directory of Open Access Journals (Sweden)
P. Todorovic
1987-01-01
Full Text Available In applications, considerations on stochastic models often involve a Markov chain {ζn}0∞ with state space in R+, and a transition probability Q. For each x R+ the support of Q(x,. is [0,x]. This implies that ζ0≥ζ1≥…. Under certain regularity assumptions on Q we show that Qn(x,Bu→1 as n→∞ for all u>0 and that 1−Qn(x,Bu≤[1−Q(x,Bu]n where Bu=[0,u. Set τ0=max{k;ζk=ζ0}, τn=max{k;ζk=ζτn−1+1} and write Xn=ζτn−1+1, Tn=τn−τn−1. We investigate some properties of the imbedded Markov chain {Xn}0∞ and of {Tn}0∞. We determine all the marginal distributions of {Tn}0∞ and show that it is asymptotically stationary and that it possesses a monotonicity property. We also prove that under some mild regularity assumptions on β(x=1−Q(x,Bx, ∑1n(Ti−a/bn→dZ∼N(0,1.
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
Improved prediction error filters for adaptive feedback cancellation in hearing aids
DEFF Research Database (Denmark)
Ngo, Kim; van Waterschoot, Toon; Christensen, Mads Græsbøll;
2013-01-01
and the loudspeaker signal caused by the closed signal loop, in particular when the near-end signal is spectrally colored as is the case for a speech signal. This paper adopts a prediction-error method (PEM)-based approach to AFC, which is based on the use of decorrelating prediction error filters (PEFs). We propose...
Stability Improvements of an LCL-filter based Three-phase Active Rectifier
DEFF Research Database (Denmark)
Liserre, Marco; Dell'Aquila, Antonio; Blaabjerg, Frede
2002-01-01
for the ac inductors making them expensive and bulky. Moreover the dynamic of the system becomes poor with so high value of inductance. On the contrary to adopt an LCL-filter configuration allows to use reduced values of the inductances (preserving dynamic) and to reduce the switching frequency pollution...
Wit, de A.J.W.; Diepen, van C.A.
2007-01-01
Uncertainty in spatial and temporal distribution of rainfall in regional crop yield simulations comprises a major fraction of the error on crop model simulation results. In this paper we used an Ensemble Kalman filter (EnKF) to assimilate coarse resolution satellite microwave sensor derived soil
Robust Monotone Iterates for Nonlinear Singularly Perturbed Boundary Value Problems
Directory of Open Access Journals (Sweden)
Boglaev Igor
2009-01-01
Full Text Available This paper is concerned with solving nonlinear singularly perturbed boundary value problems. Robust monotone iterates for solving nonlinear difference scheme are constructed. Uniform convergence of the monotone methods is investigated, and convergence rates are estimated. Numerical experiments complement the theoretical results.
Regularization and Iterative Methods for Monotone Variational Inequalities
Directory of Open Access Journals (Sweden)
Xiubin Xu
2010-01-01
Full Text Available We provide a general regularization method for monotone variational inequalities, where the regularizer is a Lipschitz continuous and strongly monotone operator. We also introduce an iterative method as discretization of the regularization method. We prove that both regularization and iterative methods converge in norm.
LIMITED MEMORY BFGS METHOD FOR NONLINEAR MONOTONE EQUATIONS
Institute of Scientific and Technical Information of China (English)
Weijun Zhou; Donghui Li
2007-01-01
In this paper, we propose an algorithm for solving nonlinear monotone equations by combining the limited memory BFGS method (L-BFGS) with a projection method. We show that the method is globally convergent if the equation involves a Lipschitz continuous monotone function. We also present some preliminary numerical results.
Positivity and Monotonicity Preserving Biquartic Rational Interpolation Spline Surface
Directory of Open Access Journals (Sweden)
Xinru Liu
2014-01-01
Full Text Available A biquartic rational interpolation spline surface over rectangular domain is constructed in this paper, which includes the classical bicubic Coons surface as a special case. Sufficient conditions for generating shape preserving interpolation splines for positive or monotonic surface data are deduced. The given numeric experiments show our method can deal with surface construction from positive or monotonic data effectively.
Monotone complete C*-algebras and generic dynamics
Saitô, Kazuyuki
2015-01-01
This monograph is about monotone complete C*-algebras, their properties and the new classification theory. A self-contained introduction to generic dynamics is also included because of its important connections to these algebras. Our knowledge and understanding of monotone complete C*-algebras has been transformed in recent years. This is a very exciting stage in their development, with much discovered but with many mysteries to unravel. This book is intended to encourage graduate students and working mathematicians to attack some of these difficult questions. Each bounded, upward directed net of real numbers has a limit. Monotone complete algebras of operators have a similar property. In particular, every von Neumann algebra is monotone complete but the converse is false. Written by major contributors to this field, Monotone Complete C*-algebras and Generic Dynamics takes readers from the basics to recent advances. The prerequisites are a grounding in functional analysis, some point set topology and an eleme...
Directory of Open Access Journals (Sweden)
F. Mavromatakis
2007-09-01
Full Text Available In this work we explore the effect of the contribution of the solar spectrum to the recorded signal in wavelengths outside the typical 940-nm filter's bandwidth. We employ gaussian-shaped filters as well as actual filter transmission curves, mainly AERONET data, to study the implications imposed by the non-zero out-of-band contribution to the coefficients used to derive precipitable water from the measured water vapour band transmittance. Published parameterized transmittance functions are applied to the data to determine the filter coefficients. We also introduce an improved, three-parameter, fitting function that can describe the theoretical data accurately, with significantly less residual effects than with the existing functions. The moderate-resolution SMARTS radiative transfer code is used to predict the incident spectrum outside the filter bandpass for different atmospheres, solar geometries and aerosol optical depths. The high-resolution LBLRTM radiative transfer code is used to calculate the water vapour transmittance in the 940-nm band. The absolute level of the out-of-band transmittance has been chosen to range from 10^{−6} to 10^{−4}, and typical response curves of commercially available silicon photodiodes are included into the calculations.
It is shown that if the out-of-band transmittance effect is neglected, as is generally the case, then the derived columnar water vapour is mainly underestimated by a few percents. The actual error depends on the specific out-of-band transmittance, optical air mass of observation and water vapour amount. Further investigations will use experimental data from field campaigns to validate these findings.
Zha, Yikun; Wei, Jingsong; Gan, Fuxi
2013-04-01
With the continuous development of the field of information technology, there has been a demand for recording mark size of optical data storage, optical imaging resolving power, and characteristic linewidth of photolithography to reach nanoscale. However, it is very difficult to realize the goal due to the optical diffraction limit restrictions. Much interest has focused on the study of optical far-field super-resolution spot by using pupil filters. However, common concerns have continued to plague super-resolving pupil filters based on either scalar diffraction theory or vector diffraction theory. These concerns include the fact that the side lobe becomes non-negligible when the central lobe is squeezed to a certain extent. Moreover, it is difficult to reduce the super-resolving spot to nanoscale. In this work, we proposed a novel method to combine the super-resolving pupil filters with nonlinear saturable absorption thin films to reduce the central spot size to nanoscale, lower the intensity ratio of side lobe to central lobe, and elongate the depth of focus or tunable tolerance distance between the super-resolving spot and sample. The simulated results indicate that by using the three-zone annular binary phase filter as the super-resolving pupil filter and Sb2Te3 as the nonlinear saturable absorption thin films, the central spot size can be reduced to nanoscale, the side lobe intensity is squeezed to about 10% of the central lobe intensity, and the tunable tolerance distance between the super-resolving spot and the sample is about two times that of the depth of focus of the diffraction limited spot at the incident laser wavelength of 405 nm and the numerical aperture of focusing lens of 0.95. The combination of the super-resolving pupil filters with the nonlinear saturable absorption thin films is very useful for nano-optical data storage, maskless nanolithography, and nano-optical imaging. It is also easy to use in actual applications because of the operation
Yan, Menglong; Blaschke, Thomas; Tang, Hongzhao; Xiao, Chenchao; Sun, Xian; Zhang, Daobing; Fu, Kun
2017-03-01
Airborne laser scanning (ALS) is a technique used to obtain Digital Surface Models (DSM) and Digital Terrain Models (DTM) efficiently, and filtering is the key procedure used to derive DTM from point clouds. Generating seed points is an initial step for most filtering algorithms, whereas existing algorithms usually define a regular window size to generate seed points. This may lead to an inadequate density of seed points, and further introduce error type I, especially in steep terrain and forested areas. In this study, we propose the use of objectbased analysis to derive surface complexity information from ALS datasets, which can then be used to improve seed point generation.We assume that an area is complex if it is composed of many small objects, with no buildings within the area. Using these assumptions, we propose and implement a new segmentation algorithm based on a grid index, which we call the Edge and Slope Restricted Region Growing (ESRGG) algorithm. Surface complexity information is obtained by statistical analysis of the number of objects derived by segmentation in each area. Then, for complex areas, a smaller window size is defined to generate seed points. Experimental results show that the proposed algorithm could greatly improve the filtering results in complex areas, especially in steep terrain and forested areas.
Yao, Yu; Cheng, Kai; Zhou, Zhi-Jie; Zhang, Bang-Cheng; Dong, Chao; Zheng, Sen
2015-11-01
A tracked vehicle has been widely used in exploring unknown environments and military fields. In current methods for suiting soil conditions, soil parameters need to be given and the traction performance cannot always be satisfied on soft soil. To solve the problem, it is essential to estimate track-soil parameters in real-time. Therefore, a detailed mathematical model is proposed for the first time. Furthermore, a novel algorithm which is composed of Kalman filter (KF) and improved strong tracking filter (STF) is developed for online track-soil estimation and named as KF-ISTF. By this method, the KF is used to estimate slip parameters, and the ISTF is used to estimate motion states. Then the key soil parameters can be estimated by using a suitable soil model. The experimental results show that equipped with the estimation algorithm, the proposed model can be used to estimate the track-soil parameters, and make the traction performance satisfied with soil conditions.
Sicardi, V; Ortiz, J; Rincón, A; Jorba, O; Pay, M T; Gassó, S; Baldasano, J M
2012-02-01
The CALIOPE air quality modelling system has been used to diagnose ground level O(3) concentration for the year 2004, over the Iberian Peninsula. We investigate the improvement in the simulation of daily O(3) maximum by the use of a post-processing such as the Kalman filter bias-adjustment technique. The Kalman filter bias-adjustment technique is a recursive algorithm to optimally estimate bias-adjustment terms from previous measurements and model results. The bias-adjustment technique improved the simulation of daily O(3) maximum for the entire year and the all the stations considered over the whole domain. The corrected simulation presents improvements in statistical indicators such as correlation, root mean square error, mean bias, and gross error. After the post-processing the exceedances of O(3) concentration limits, as established by the European Directive 2008/50/CE, are better reproduced and the uncertainty of the modelling system, as established by the European Directive 2008/50/CE, is reduced from 20% to 7.5%. Such uncertainty in the model results is under the established EU limit of the 50%. Significant improvements in the O(3) timing and amplitude of the daily cycle are also observed after the post-processing. The systematic improvements in the O(3) maximum simulations suggest that the Kalman filter post-processing method is a suitable technique to reproduce accurate estimate of ground-level O(3) concentration. With this study we evince that the adjusted O(3) concentrations obtained after the post-process of the results from the CALIOPE system are a reliable means for real near time O(3) forecasts.
Performance evaluation of a dual-flow recharge filter for improving groundwater quality.
Samuel, Manoj P; Senthilvel, S; Mathew, Abraham C
2014-07-01
A dual-flow multimedia stormwater filter integrated with a groundwater recharge system was developed and tested for hydraulic efficiency and pollutant removal efficiency. The influent stormwater first flows horizontally through the circular layers of planted grass and biofibers. Subsequently, the flow direction changes to a vertical direction so that water moves through layers of pebbles and sand and finally gets recharged to the deep aquifers. The media in the sequence of vegetative medium:biofiber to pebble:sand were filled in nine proportions and tested for the best performing combination. Three grass species, viz., Typha (Typha angustifolia), Vetiver (Chrysopogon zizanioides), and St. Augustine grass (Stenotaphrum secundatum), were tested as the best performing vegetative medium. The adsorption behavior of Coconut (Cocos nucifera) fiber, which was filled in the middle layer, was determined by a series of column and batch studies.The dual-flow filter showed an increasing trend in hydraulic efficiency with an increase in flowrate. The chemical removal efficiency of the recharge dual-flow filter was found to be very high in case of K+ (81.6%) and Na+ (77.55%). The pH normalizing efficiency and electrical conductivity reduction efficiency were also recorded as high. The average removal percentage of Ca2+ was moderate, while that of Mg2+ was very low. The filter proportions of 1:1 to 1:2 (plant:fiber to pebble:sand) showed a superior performance compared to all other proportions. Based on the estimated annual costs and returns, all the financial viability criteria (internal rate of return, net present value, and benefit-cost ratio) were found to be favorable and affordable to farmers in terms of investing in the developed filtration system.
Do low-cost ceramic water filters improve water security in rural South Africa?
Lange, Jens; Materne, Tineke; Grüner, Jörg
2016-01-01
This study examines the performance of a low-cost ceramic candle filter system (CCFS) for point of use (POU) drinking water treatment in the village of Hobeni, Eastern Cape Province, South Africa. A stepwise laboratory test documented the negative effects of repeated loading and ambient field temperatures. Moreover, CCFS were distributed in Hobeni and a survey was carried out among their users. The performance of 51 CCFS was evaluated by dip slides and related to human factors. Already after ...
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.
Improving the response of accelerometers for automotive applications by using LMS adaptive filters.
Hernandez, Wilmar; de Vicente, Jesús; Sergiyenko, Oleg; Fernández, Eduardo
2010-01-01
In this paper, the least-mean-squares (LMS) algorithm was used to eliminate noise corrupting the important information coming from a piezoresisitive accelerometer for automotive applications. This kind of accelerometer is designed to be easily mounted in hard to reach places on vehicles under test, and they usually feature ranges from 50 to 2,000 g (where is the gravitational acceleration, 9.81 m/s(2)) and frequency responses to 3,000 Hz or higher, with DC response, durable cables, reliable performance and relatively low cost. However, here we show that the response of the sensor under test had a lot of noise and we carried out the signal processing stage by using both conventional and optimal adaptive filtering. Usually, designers have to build their specific analog and digital signal processing circuits, and this fact increases considerably the cost of the entire sensor system and the results are not always satisfactory, because the relevant signal is sometimes buried in a broad-band noise background where the unwanted information and the relevant signal sometimes share a very similar frequency band. Thus, in order to deal with this problem, here we used the LMS adaptive filtering algorithm and compare it with others based on the kind of filters that are typically used for automotive applications. The experimental results are satisfactory.
Entis, P
1990-01-01
A collaborative study was carried out in 30 laboratories to validate improvements to the official final action hydrophobic grid membrane filter (HGMF) screening method for Salmonella in foods, 985.42, by comparing the performance of the improved HGMF method against that of the AOAC/BAM conventional culture method. Six products were included in the collaborative study: milk chocolate, raw deboned poultry meat, black pepper, soy flour, egg yolk powder, and nonfat dry milk. The raw deboned poultry meat was naturally contaminated with Salmonella, and the remaining 5 products were each inoculated in advance with low levels of individual Salmonella serotypes. The AOAC/BAM method produced 11 false negative results and the improved HGMF method produced 18 false negative results. The improved HGMF Salmonella method has been approved interim official first action for all foods to replace the HGMF official final action method, 985.42.
Lee, Yongbum; Takahashi, Noriyuki; Tsai, Du-Yih; Fujita, Hiroshi
2006-03-01
Detection of early infarct signs on non-enhanced CT is mandatory in patients with acute ischemic stroke. We present a method for improving the detectability of early infarct signs of acute ischemic stroke. This approach is considered as the first step for computer-aided diagnosis in acute ischemic stroke. Obscuration of the gray-white matter interface at the lentiform nucleus or the insular ribbon has been an important early infarct sign, which affects decisions on thrombolytic therapy. However, its detection is difficult, since the early infarct sign is subtle hypoattenuation. In order to improve the detectability of the early infarct sign, an image processing being able to reduce local noise with edges preserved is desirable. To cope with this issue, we devised an adaptive partial smoothing filter (APSF). Because the APSF can markedly improve the visibility of the normal gray-white matter interface, the detection of conspicuity of obscuration of gray-white matter interface due to hypoattenuation could be increased. The APSF is a specifically designed filter used to perform local smoothing using a variable filter size determined by the distribution of pixel values of edges in the region of interest. By adjusting four parameters of the APSF, an optimal condition for image enhancement can be obtained. In order to determine a major one of the parameters, preliminary simulation was performed by using composite images simulated the gray-white matter. The APSF based on preliminary simulation was applied to several clinical CT scans in hyperacute stroke patients. The results showed that the detectability of early infarct signs is much improved.
Chen, Baojiang; Qin, Jing
2014-05-10
In statistical analysis, a regression model is needed if one is interested in finding the relationship between a response variable and covariates. When the response depends on the covariate, then it may also depend on the function of this covariate. If one has no knowledge of this functional form but expect for monotonic increasing or decreasing, then the isotonic regression model is preferable. Estimation of parameters for isotonic regression models is based on the pool-adjacent-violators algorithm (PAVA), where the monotonicity constraints are built in. With missing data, people often employ the augmented estimating method to improve estimation efficiency by incorporating auxiliary information through a working regression model. However, under the framework of the isotonic regression model, the PAVA does not work as the monotonicity constraints are violated. In this paper, we develop an empirical likelihood-based method for isotonic regression model to incorporate the auxiliary information. Because the monotonicity constraints still hold, the PAVA can be used for parameter estimation. Simulation studies demonstrate that the proposed method can yield more efficient estimates, and in some situations, the efficiency improvement is substantial. We apply this method to a dementia study.
Energy Technology Data Exchange (ETDEWEB)
Takahashi, N.; Lee, Y.; Tsai, D. Y.; Ishii, K.; Kinoshita, T.; Tamura, H.; Kimura, M. (Dept. of Radiological Technology, School of Health Sciences, Niigata Univ., Niigata (Japan))
2008-09-15
Background: Much attention has been directed toward identifying early signs of cerebral ischemia on computed tomography (CT) images. Hypoattenuation of ischemic brain parenchyma has been found to be the most frequent early sign. Purpose: To evaluate the effect of a previously proposed adaptive smoothing filter for improving detection of parenchymal hypoattenuation of acute ischemic stroke on unenhanced CT images. Material and Methods: Twenty-six patients with parenchymal hypoattenuation and 49 control subjects without hypoattenuation were retrospectively selected in this study. The adaptive partial median filter (APMF) designed for improving detectability of hypoattenuation areas on unenhanced CT images was applied. Seven radiologists, including four certified radiologists and three radiology residents, indicated their confidence level regarding the presence (or absence) of hypoattenuation on CT images, first without and then with the APMF processed images. Their performances without and with the APMF processed images were evaluated by receiver operating characteristic (ROC) analysis. Results: The mean areas under the ROC curves (AUC) for all observers increased from 0.875 to 0.929 (P=0.002) when the radiologists observed with the APMF processed images. The mean sensitivity in the detection of hypoattenuation significantly improved, from 69% (126 of 182 observations) to 89% (151 of 182 observations), when employing the APMF (P=0.012). The specificity, however, was unaffected by the APMF (P=0.41). Conclusion: The APMF has the potential to improve the detection of parenchymal hypoattenuation of acute ischemic stroke on unenhanced CT images
Cheng, Xuemin; Hao, Qun; Xie, Mengdi
2016-04-07
Video stabilization is an important technology for removing undesired motion in videos. This paper presents a comprehensive motion estimation method for electronic image stabilization techniques, integrating the speeded up robust features (SURF) algorithm, modified random sample consensus (RANSAC), and the Kalman filter, and also taking camera scaling and conventional camera translation and rotation into full consideration. Using SURF in sub-pixel space, feature points were located and then matched. The false matched points were removed by modified RANSAC. Global motion was estimated by using the feature points and modified cascading parameters, which reduced the accumulated errors in a series of frames and improved the peak signal to noise ratio (PSNR) by 8.2 dB. A specific Kalman filter model was established by considering the movement and scaling of scenes. Finally, video stabilization was achieved with filtered motion parameters using the modified adjacent frame compensation. The experimental results proved that the target images were stabilized even when the vibrating amplitudes of the video become increasingly large.
The Number of Monotone and Self-Dual Boolean Functions
Directory of Open Access Journals (Sweden)
Haviarova L.
2014-12-01
Full Text Available In the present paper we study properties of pre-complete class of Boolean functions - monotone Boolean functions. We discuss interval graph, the abbreviated d.n.f., a minimal d.n.f. and a shortest d.n.f. of this function. Then we present a d.n.f. with the highest number of conjunctionsand we determinate the exact number of them. We count the number of monotone Boolean functions with some special properties. In the end we estimate the number of Boolean functionthat are monotone and self-dual at the same time.
Ratio Monotonicity of Polynomials Derived from Nondecreasing Sequences
Chen, William Y C; Zhou, Elaine L F
2010-01-01
The ratio monotonicity of a polynomial is a stronger property than log-concavity. Let P(x) be a polynomial with nonnegative and nondecreasing coefficients. We prove the ratio monotone property of P(x+1), which leads to the log-concavity of P(x+c) for any $c\\geq 1$ due to Llamas and Mart\\'{\\i}nez-Bernal. As a consequence, we obtain the ratio monotonicity of the Boros-Moll polynomials obtained by Chen and Xia without resorting to the recurrence relations of the coefficients.
Schifman, L. A.; Kasaraneni, V.; Boving, T. B.; Oyanedel-Craver, V.
2013-12-01
Stormwater runoff, particularly in urban areas, contains high concentrations of pathogens that are often cited as one of the main reasons for beach closings and other water quality issues in coastal areas. Commonly found contaminants in runoff are often addressed by structural best management practices (BMP) that capture and treat the runoff before discharging it. Many BMP, such as tree filters, act as primary filtration devices that attenuate total suspended solids, nutrients, and heavy metals from runoff, but typically these BMPs are not designed to treat bacteria and have only minor petroleum hydrocarbon (PH) treatment capabilities. To address this shortcoming, the contaminant retention of an alternative sorption material was compared to expanded shale that is usually used in tree filters. Red cedar wood chips were modified with either Quaternary Ammonium Silane (QAS) or Silver Nanoparticles (AgNPs) to provide antimicrobial properties to the matrix and/or exploit their affinity to sorb PH, particularly polycyclic aromatic hydrocarbons (PAH). Results show that the wood chips exhibit the highest sorption capacity for QAS, making this material favorable for treating bacteria, while at the same time attenuating PAH by sorption processes. In the case of AgNP amendment to wood, less AgNP uptake and more desorption from the wood matrix was observed, making this amendment less favorable for bacteria deactivation. Batch experiments show that wood chips modified with QAS can remove up to 3 orders of magnitude of bacteria and retain up to 0.1 mg/g of PAH compared to shale, which has very limited bacteria deactivation (less than one order of magnitude) a PAH retention capacity of 0.04 mg/g. In this talk, the contaminant removal efficiency of the modified and unmodified materials will be discussed on the background of how these materials may find use in enhanced treatment of stormwater in tree filter BMPs.
Ruffio, Jean-Baptiste; Macintosh, Bruce; Wang, Jason J.; Pueyo, Laurent; Nielsen, Eric L.; De Rosa, Robert J.; Czekala, Ian; Marley, Mark S.; Arriaga, Pauline; Bailey, Vanessa P.; Barman, Travis; Bulger, Joanna; Chilcote, Jeffrey; Cotten, Tara; Doyon, Rene; Duchêne, Gaspard; Fitzgerald, Michael P.; Follette, Katherine B.; Gerard, Benjamin L.; Goodsell, Stephen J.; Graham, James R.; Greenbaum, Alexandra Z.; Hibon, Pascale; Hung, Li-Wei; Ingraham, Patrick; Kalas, Paul; Konopacky, Quinn; Larkin, James E.; Maire, Jérôme; Marchis, Franck; Marois, Christian; Metchev, Stanimir; Millar-Blanchaer, Maxwell A.; Morzinski, Katie M.; Oppenheimer, Rebecca; Palmer, David; Patience, Jennifer; Perrin, Marshall; Poyneer, Lisa; Rajan, Abhijith; Rameau, Julien; Rantakyrö, Fredrik T.; Savransky, Dmitry; Schneider, Adam C.; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Wallace, J. Kent; Ward-Duong, Kimberly; Wiktorowicz, Sloane; Wolff, Schuyler
2017-06-01
We present a new matched-filter algorithm for direct detection of point sources in the immediate vicinity of bright stars. The stellar point-spread function (PSF) is first subtracted using a Karhunen-Loéve image processing (KLIP) algorithm with angular and spectral differential imaging (ADI and SDI). The KLIP-induced distortion of the astrophysical signal is included in the matched-filter template by computing a forward model of the PSF at every position in the image. To optimize the performance of the algorithm, we conduct extensive planet injection and recovery tests and tune the exoplanet spectra template and KLIP reduction aggressiveness to maximize the signal-to-noise ratio (S/N) of the recovered planets. We show that only two spectral templates are necessary to recover any young Jovian exoplanets with minimal S/N loss. We also developed a complete pipeline for the automated detection of point-source candidates, the calculation of receiver operating characteristics (ROC), contrast curves based on false positives, and completeness contours. We process in a uniform manner more than 330 data sets from the Gemini Planet Imager Exoplanet Survey and assess GPI typical sensitivity as a function of the star and the hypothetical companion spectral type. This work allows for the first time a comparison of different detection algorithms at a survey scale accounting for both planet completeness and false-positive rate. We show that the new forward model matched filter allows the detection of 50% fainter objects than a conventional cross-correlation technique with a Gaussian PSF template for the same false-positive rate.
Johnson, R. A.; Shoshitaishvili, E.; Sorenson, L. S.
2001-12-01
The Cheyenne Belt in southeastern Wyoming separates Archean Wyoming Craton from accreted juvenile Proterozoic crust making it one of the fundamental sutures in the Proterozoic assemblage of western North America. As one of the multidisciplinary components of the Continental Dynamics - Rocky Mountains Transect project (CDROM), reflection seismic data were acquired from south-central Wyoming to central Colorado to characterize crustal structure associated with this boundary and younger Proterozoic shear zones to the south. In addition to acquisition of more conventional vertical-component data, 3-component data were acquired to better constrain rock properties and reflection directionality, providing information that tends to be lost with one-component recording. In order to achieve the highest possible signal-to-noise ratios in the processed data, considerable work was focused on removal of noise caused by private vehicles driving on forest roads during active recording and, perhaps more problematical, harmonic noise generated from power-line and other electrical-equipment interference. Noise generated from these sources was successfully attenuated using 1) short-window 2D FFT filtering to remove irregular, high-amplitude vehicular noise, and 2) harmonic-noise-subtraction algorithms developed at the University of Arizona to remove harmonic electrical-induction noise. This latter filtering procedure used a time-domain-based method of automatic estimation of noise frequencies and their amplitudes, followed by subtraction of these estimated anomalous harmonics from the data. Since the technique estimates the best fit of noise for the entire trace, subtraction of the noise avoids many of the deleterious effects of simple notch filtering. After noise removal, it was possible to pick both P-wave and S-wave first arrivals and model shallow subsurface rock properties. This model provides a link between deeper events and the surface geology.
Short term wave forecasting, using digital filters, for improved control of Wave Energy Converters
DEFF Research Database (Denmark)
Tedd, James; Frigaard, Peter
2007-01-01
experimentally. Results are shown form measurements taken on the Wave Dragon prototype device, a floating overtopping device situated in Northern Denmark. In this case the method is able to accurately predict the surface elevation at the device 11.2 seconds before the measurement is made. This is sufficient......This paper presents a Digital Filter method for real time prediction of waves incident upon a Wave Energy device. The method transforms waves measured at a point ahead of the device, to expected waves incident on the device. The relationship between these incident waves and power capture is derived...
DPC controlled three-phase active filter for power quality improvement
Energy Technology Data Exchange (ETDEWEB)
Chaoui, Abdelmadjid; Krim, Fateh [Laboratoire d' Electronique de Puissance et Commande Industrielle (LEPCI), Universite de Setif (Algeria); Gaubert, Jean-Paul; Rambault, Laurent [Laboratoire d' Automatique et d' Informatique Industrielle (LAII-ESIP), Universite de Poitiers (France)
2008-10-15
This paper presents a new control method entitled direct power control (DPC) for shunt active power filtering (5th, 7th, 11th,..) (SAPF), which is applied to eliminate line current harmonics and compensate reactive power. Its main goal is to rebuild active and reactive powers to be compared to references values using hysteresis control. The outputs of hysteresis controllers associated with a switching table, control the instantaneous active and reactive power by selecting the optimum switching state of the voltage source inverter (VSI). A theoretical analysis with a complete simulation of the system and experimental results are presented to prove the excellent performance of the proposed control technique. (author)
Fly-ash-amended sand as filter media in bioretention cells to improve phosphorus removal.
Zhang, Wei; Brown, Glenn O; Storm, Daniel E; Zhang, Hailin
2008-06-01
This study identified material with high phosphorus sorption suitable for bioretention filter media. Materials examined were fly ash, two expanded shales, peat moss, limestone, and two common Oklahoma soils--Teller loam and Dougherty sand. The peat moss was a phosphorus source, while the two soils, limestone, and one expanded shale had only modest sorption capacity. One expanded shale and the fly ash had significant phosphorus sorption. Fly ash is unsuitable for use in a pure form, as a result of its low permeability, but phosphorus sorption on the sand was increased significantly with the incorporation of small amounts of fly ash. Column leaching experiments found that the sand with 2.5 and 5% fly ash and the better expanded shale had linear, non-equilibrium transport retardation factors of 272, 1618, and 185, with first-order rate coefficients of 0.153, 0.0752, and 0.113 hour(-1), respectively. Desorption experiments showed that the phosphorus sorption on the sand/fly ash mixture is largely nonreversible. Transport simulation assuming a 1-m-deep sand/fly ash treatment layer, with 5% of the watershed area, showed that the sand/fly ash filter media could effectively treat 1 mg/L influent for 12 years in a paved watershed and 34 years in a grassed watershed before exceeding Oklahoma's scenic rivers' phosphorus criterion of 0.037 mg/L. Significant phosphorus removal would continue for over 100 years.
Auditory filters at low-frequencies
DEFF Research Database (Denmark)
Orellana, Carlos Andrés Jurado; Pedersen, Christian Sejer; Møller, Henrik
2009-01-01
-ear transfer function), the asymmetry of the auditory filter changed from steeper high-frequency slopes at 1000 Hz to steeper low-frequency slopes below 100 Hz. Increasing steepness at low-frequencies of the middle-ear high-pass filter is thought to cause this effect. The dynamic range of the auditory filter...... was found to steadily decrease with decreasing center frequency. Although the observed decrease in filter bandwidth with decreasing center frequency was only approximately monotonic, the preliminary data indicates the filter bandwidth does not stabilize around 100 Hz, e.g. it still decreases below...
On the Monotone Iterative Method for Set Valued Equation
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
This paper deals with the monotone iterative method for set- valued operator equation in ordered normed space. Some results for the case of single valued operator are generalized here, as an application, a discontinuous nonlinear differential equation problem is discussed.
Monotone method for initial value problem for fractional diffusion equation
Institute of Scientific and Technical Information of China (English)
ZHANG Shuqin
2006-01-01
Using the method of upper and lower solutions and its associated monotone iterative, consider the existence and uniqueness of solution of an initial value problem for the nonlinear fractional diffusion equation.
Variable selection in monotone single-index models via the adaptive LASSO.
Foster, Jared C; Taylor, Jeremy M G; Nan, Bin
2013-09-30
We consider the problem of variable selection for monotone single-index models. A single-index model assumes that the expectation of the outcome is an unknown function of a linear combination of covariates. Assuming monotonicity of the unknown function is often reasonable and allows for more straightforward inference. We present an adaptive LASSO penalized least squares approach to estimating the index parameter and the unknown function in these models for continuous outcome. Monotone function estimates are achieved using the pooled adjacent violators algorithm, followed by kernel regression. In the iterative estimation process, a linear approximation to the unknown function is used, therefore reducing the situation to that of linear regression and allowing for the use of standard LASSO algorithms, such as coordinate descent. Results of a simulation study indicate that the proposed methods perform well under a variety of circumstances and that an assumption of monotonicity, when appropriate, noticeably improves performance. The proposed methods are applied to data from a randomized clinical trial for the treatment of a critical illness in the intensive care unit.
Action-Maslov Homomorphism for Monotone Symplectic Manifolds
Branson, Mark
2009-01-01
We explore conditions under which the action-Maslov homomorphism vanishes on monotone symplectic manifolds. Our strategy involves showing that the units in the quantum homology, and thus the Seidel element, have a very specific form. Then we use induction to show that other relevant Gromov-Witten invariants vanish. We prove that these conditions hold for monotone products of projective spaces and for the Grassmannian of 2-planes in $\\C^4$.
Completely monotonic functions related to logarithmic derivatives of entire functions
DEFF Research Database (Denmark)
Pedersen, Henrik Laurberg
2011-01-01
The logarithmic derivative l(x) of an entire function of genus p and having only non-positive zeros is represented in terms of a Stieltjes function. As a consequence, (-1)p(xml(x))(m+p) is a completely monotonic function for all m ≥ 0. This generalizes earlier results on complete monotonicity...... of functions related to Euler's psi-function. Applications to Barnes' multiple gamma functions are given....
Isotonicity of the projection onto the monotone cone
Németh, A B
2012-01-01
A wedge (i.e., a closed nonempty set in the Euclidean space stable under addition and multiplication with non-negative scalars) induces by a standard way a semi-order (a reflexive and transitive binary relation) in the space. The wedges admitting isotone metric projection with respect to the semi-order induced by them are characterized. The obtained result is used to show that the monotone wedge (called monotone cone in regression theory) admits isotone projection.
Monotonic loading of circular surface footings on clay
Energy Technology Data Exchange (ETDEWEB)
Ibsen, Lars Bo; Barari, Amin [Aalborg University, Aalborg (Denmark)
2011-12-15
Appropriate modeling of offshore foundations under monotonic loading is a significant challenge in geotechnical engineering. This paper reports experimental and numerical analyses, specifically investigating the response of circular surface footings during monotonic loading and elastoplastic behavior during reloading. By using the findings presented in this paper, it is possible to extend the model to simulate the vertical-load displacement response of offshore bucket foundations.
Layered neural networks with non-monotonic transfer functions
Katayama, Katsuki; Sakata, Yasuo; Horiguchi, Tsuyoshi
2003-01-01
We investigate storage capacity and generalization ability for two types of fully connected layered neural networks with non-monotonic transfer functions; random patterns are embedded into the networks by a Hebbian learning rule. One of them is a layered network in which a non-monotonic transfer function of even layers is different from that of odd layers. The other is a layered network with intra-layer connections, in which the non-monotonic transfer function of inter-layer is different from that of intra-layer, and inter-layered neurons and intra-layered neurons are updated alternately. We derive recursion relations for order parameters for those layered networks by the signal-to-noise ratio method. We clarify that the storage capacity and the generalization ability for those layered networks are enhanced in comparison with those with a conventional monotonic transfer function when non-monotonicity of the transfer functions is selected optimally. We also point out that some chaotic behavior appears in the order parameters for the layered networks when non-monotonicity of the transfer functions increases.
Improved Fastslam2.0 Based on the H4 Filter for Intelligent Mobile Robot
Directory of Open Access Journals (Sweden)
Qi Zhang
2012-08-01
Full Text Available This study proposes hybrid H∞ Fast SLAM algorithm as a robust and effective SLAM solution. In usual FastSLAM2.0, a priori knowledge of the process and the statistics of measurement noise are assumed to be Gaussian motion disturbances. However, in most application these matrixes are unknown or can’t be assumed as Gaussian motion disturbances. The main advantage of the H∞ estimator is that it makes no assumption about the disturbances and it has the ability which all conceivable disturbances can be satisfied. We use the H∞ filter to handle the process and measurement noise covariance matrices Qt and Rt. And the k-step look-ahead proposal distribution is added to calculate importance weight of particles. Simulation results in different environments and consistency of the proposed approach are presented, demonstrating the superiority of the proposed approach.
Power quality improvement using DPC controlled three-phase shunt active filter
Energy Technology Data Exchange (ETDEWEB)
Chaoui, Abdelmadjid [Laboratoire d' Automatique et d' Informatique Industrielle (LAII-ESIP), Universite de Poitiers (France); Gaubert, Jean-Paul; Krim, Fateh [Laboratoire d' Electronique de Puissance et Commande Industrielle (LEPCI), Universite de Setif (Algeria)
2010-06-15
This paper presents a new control method entitled direct power control (DPC) for shunt active power filter (APF), which is applied to eliminate line current harmonics and compensate reactive power. Its main goal is to rebuild active and reactive source powers to be compared to references values using hysteresis control. The active power reference is issue of DC-side of inverter and reactive power reference is set to zero for unity power factor. The outputs of hysteresis controllers associated with a switching table, control the instantaneous active and reactive power by selecting the optimum switching state of the voltage source inverter (VSI). A theoretical analysis with a complete simulation of the system and experimental results are presented to prove the excellent performance of the proposed technique. (author)
Improve the Handover Decision Based on a Kalman Filter and Fuzzy
Directory of Open Access Journals (Sweden)
Rula Sami Khudhair
2017-07-01
Full Text Available The major aim of a Mobile network system is to provide premium Quality of Service (QoS to the user by an establishment of guaranteed seamless connection between the users. The radio signal strength has been regularly measured from mobile station and BTS in a cellular network. If the BTS detects a decrease in the radio signal, it initiates a handoff request. Many parameters have been effected by the handoff decision. In this paper, a proposed algorithm has been presented to track the mobile location, distance, and velocity by using Kalman filter, while, monitoring the mobile direction, and measure RSS. Then applying the Fuzzy Membership Function of RSS and distance to decide the handoff decision. From the results, it is cleared the advancement in the handoff performance.
Banerjee, Pradipta K.; Datta, Asit K.
2013-02-01
The paper proposes an improved strategy for face recognition using correlation filter under varying lighting conditions and occlusion where spatial domain preprocessing is carried out by two convolution kernels. The first convolution kernel is a contour kernel for emphasizing high frequency components of face image and the other kernel is a smoothing kernel used for minimization of noise those may arise due to preprocessing. The convolution kernels are obtained by training a generalized regression neural network using enhanced face features. Face features are enhanced by conventional principal component analysis. The proposed method reduces the false acceptance rate and false rejection rate in comparison to other standard correlation filtering techniques. Moreover, the processing is fast when compared to the existing illumination normalization techniques. A scheme of hardware implementation of all optical correlation technique is also suggested based on single spatial light modulator in a beam folding architecture. Two benchmark databases YaleB and PIE are used for performance verification of the proposed scheme and the improved results are obtained for both illumination variations and occlusions in test face images.
Directory of Open Access Journals (Sweden)
Yanjian Peng
2016-04-01
Full Text Available Unlike the traditional method for power quality improvement and low-voltage ride through (LVRT capability enhancement of wind farms, this paper proposes a new wind power integrated system by means of an inductive filtering method, especially if it contains a grid-connected transformer, a static synchronous compensator (STATCOM and fully-tuned (FT branches. First, the main circuit topology of the new wind power integrated system is presented. Then, the mathematical model is established to reveal the mechanism of harmonic suppression and the reactive compensation of the proposed wind power integrated system, and then the realization conditions of the inductive filtering method is obtained. Further, the control strategy of STATCOM is introduced. Based on the measured data for a real wind farm, the simulation studies are carried out to illustrate the performance of the proposed new wind power integrated system. The results indicate that the new system can not only enhance the LVRT capability of wind farms, but also prevent harmonic components flowing into the primary (grid winding of the grid-connected transformer. Moreover, since the new method can compensate for reactive power in a wind farm, the power factor at the grid side can be improved effectively.
Efficiency Improvement of Kalman Filter for GNSS/INS through One-Step Prediction of P Matrix
Directory of Open Access Journals (Sweden)
Qingli Li
2015-01-01
Full Text Available To meet the real-time and low power consumption demands in MEMS navigation and guidance field, an improved Kalman filter algorithm for GNSS/INS was proposed in this paper named as one-step prediction of P matrix. Quantitative analysis of field test datasets was made to compare the navigation accuracy with the standard algorithm, which indicated that the degradation caused by the simplified algorithm is small enough compared to the navigation errors of the GNSS/INS system itself. Meanwhile, the computation load and time consumption of the algorithm decreased over 50% by the improved algorithm. The work has special significance for navigation applications that request low power consumption and strict real-time response, such as cellphone, wearable devices, and deeply coupled GNSS/INS systems.
Directory of Open Access Journals (Sweden)
Ghosh David
2014-07-01
Full Text Available Previous investigations by others and internal investigations at Philip Morris International (PMI have shown that the standard trapping and extraction procedure used for conventional cigarettes, defined in the International Standard ISO 4387 (Cigarettes -- Determination of total and nicotine-free dry particulate matter using a routine analytical smoking machine, is not suitable for high-water content aerosols. Errors occur because of water losses during the opening of the Cambridge filter pad holder to remove the filter pad as well as during the manual handling of the filter pad, and because the commercially available filter pad holder, which is constructed out of plastic, may adsorb water. This results in inaccurate values for the water content, and erroneous and overestimated values for Nicotine Free Dry Particulate Matter (NFDPM. A modified 44 mm Cambridge filter pad holder and extraction equipment which supports in situ extraction methodology has been developed and tested. The principle of the in situ extraction methodology is to avoid any of the above mentioned water losses by extracting the loaded filter pad while kept in the Cambridge filter pad holder which is hermetically sealed by two caps. This is achieved by flushing the extraction solvent numerous times through the hermetically sealed Cambridge filter pad holder by means of an in situ extractor. The in situ methodology showed a significantly more complete water recovery, resulting in more accurate NFDPM values for high-water content aerosols compared to the standard ISO methodology. The work presented in this publication demonstrates that the in situ extraction methodology applies to a wider range of smoking products and smoking regimens, whereas the standard ISO methodology only applies to a limited range of smoking products and smoking regimens, e.g., conventional cigarettes smoked under ISO smoking regimen. In cases where a comparison of yields between the PMI HTP and
Mitchell, D A; Sault, R J
2010-01-01
In radio astronomy, reference signals from auxiliary antennas that receive only the radio frequency interference (RFI) can be modified to model the RFI environment at the astronomy receivers. The RFI can then be canceled from the astronomy signal paths. However, astronomers typically only require signal statistics. If the RFI statistics are changing slowly, the cancellation can be applied to the signal correlations at a much lower rate than is required for standard adaptive filters. In this paper we describe five canceler setups; precorrelation and postcorrelation cancelers that use one or two reference signals in different ways. The theoretical residual RFI and added noise levels are examined and are demonstrated using microwave television RFI at the Australia Telescope Compact Array. The RFI is attenuated to below the system noise, a reduction of at least 20 dB. While dual-reference cancelers add more reference noise than single-reference cancelers, this noise is zero-mean and only adds to the system noise,...
PHOTOVOLTAIC BASED SHUNT ACTIVE FILTER FOR POWER QUALITY IMPROVEMENT USING ICOSΦ THEORY
Directory of Open Access Journals (Sweden)
VIJAYAKUMAR G.
2015-11-01
Full Text Available This paper presents an optimal operation of Photovoltaic based Shunt Active Filter as (PV-SAF for significant energy conservation, harmonic mitigation and reactive power compensation. When the PV system generates excessive or equal power required to the load demand, then the coordinating logic disconnects the service grid from the load and with a consequent reduction of panel tariff and global warming gasses. The PV module is connected to the DC side of SAF through the DC-DC converter. Converter switch is controlled by fuzzy based Perturb & Observe (P&O Maximum Power Point Tracking (MPPT algorithm and it eliminates the drawback in the conventional PV system. The reference currents are extracted by the Fuzzy logic controller based ICosΦ control strategy. This proposed PV-SAF, if connected at the terminals of a small industry or a home or a small enlightening institution can avoid the use of interruptible power supply and individual stabilizer. An emulation using MATLAB Simulink is presented to validate the advantage of the proposed system.
Ploegmakers, H H; Mertens, M J; van Oort, W J
1987-01-01
In high performance liquid chromatography with electrochemical detection (HPLC/ECD) much attention has been paid to the performance of the applied detection system with respect to reliability and sensitivity. In general, insufficient attention has been paid to relatively easy to implant devices for improved collection and handling of detection signals. Four models of software filtering are studied and compared with hardware filtering. In the investigated chromatographic-electrochemical system, off-line parabolic filtering after on-line averaging of sixteen measurements proved to be the system of first choice, with respect to execution time, noise level, signal to noise ratio, peak height and resolution.
Restrepo-Agudelo, Sebastian; Roldan-Vasco, Sebastian; Ramirez-Arbelaez, Lina; Cadavid-Arboleda, Santiago; Perez-Giraldo, Estefania; Orozco-Duque, Andres
2017-08-01
The visual inspection is a widely used method for evaluating the surface electromyographic signal (sEMG) during deglutition, a process highly dependent of the examiners expertise. It is desirable to have a less subjective and automated technique to improve the onset detection in swallowing related muscles, which have a low signal-to-noise ratio. In this work, we acquired sEMG measured in infrahyoid muscles with high baseline noise of ten healthy adults during water swallowing tasks. Two methods were applied to find the combination of cutoff frequencies that achieve the most accurate onset detection: discrete wavelet decomposition based method and fixed steps variations of low and high cutoff frequencies of a digital bandpass filter. Teager-Kaiser Energy operator, root mean square and simple threshold method were applied for both techniques. Results show a narrowing of the effective bandwidth vs. the literature recommended parameters for sEMG acquisition. Both level 3 decomposition with mother wavelet db4 and bandpass filter with cutoff frequencies between 130 and 180Hz were optimal for onset detection in infrahyoid muscles. The proposed methodologies recognized the onset time with predictive power above 0.95, that is similar to previous findings but in larger and more superficial muscles in limbs. Copyright © 2017 Elsevier Ltd. All rights reserved.
Using the self-filtering property of a femtosecond filament to improve second harmonic generation.
Shwa, David; Eisenmann, Shmuel; Marcus, Gilad; Zigler, Arie
2009-04-13
In this paper we demonstrate the use of NIR femtosecond filament for improving the generation of second harmonic using a type I BBO crystal. Using this method the beam propagation factor (M(2)) of the second harmonic was improved significantly; which led to enhancement of the attainable SH intensity by up to two orders of magnitude. This method can be beneficial for applications demanding high intensities, small spot size or long interaction lengths.
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.)
Loizu, Javier; Massari, Christian; Álvarez-Mozos, Jesús; Casalí, Javier; Goñi, Mikel
2016-04-01
Assimilation of Surface Soil Moisture (SSM) observations obtained from remote sensing techniques have been shown to improve streamflow prediction at different time scales of hydrological modeling. Different sensors and methods have been tested for their application in SSM estimation, especially in the microwave region of the electromagnetic spectrum. The available observation devices include passive microwave sensors such as the Advanced Microwave Scanning Radiometer - Earth Observation System (AMSR-E) onboard the Aqua satellite and the Soil Moisture and Ocean Salinity (SMOS) mission. On the other hand, active microwave systems include Scatterometers (SCAT) onboard the European Remote Sensing satellites (ERS-1/2) and the Advanced Scatterometer (ASCAT) onboard MetOp-A satellite. Data assimilation (DA) include different techniques that have been applied in hydrology and other fields for decades. These techniques include, among others, Kalman Filtering (KF), Variational Assimilation or Particle Filtering. From the initial KF method, different techniques were developed to suit its application to different systems. The Ensemble Kalman Filter (EnKF), extensively applied in hydrological modeling improvement, shows its capability to deal with nonlinear model dynamics without linearizing model equations, as its main advantage. The objective of this study was to investigate whether data assimilation of SSM ASCAT observations, through the EnKF method, could improve streamflow simulation of mediterranean catchments with TOPLATS hydrological complex model. The DA technique was programmed in FORTRAN, and applied to hourly simulations of TOPLATS catchment model. TOPLATS (TOPMODEL-based Land-Atmosphere Transfer Scheme) was applied on its lumped version for two mediterranean catchments of similar size, located in northern Spain (Arga, 741 km2) and central Italy (Nestore, 720 km2). The model performs a separated computation of energy and water balances. In those balances, the soil
Driving performance impairments due to hypovigilance on monotonous roads.
Larue, Grégoire S; Rakotonirainy, Andry; Pettitt, Anthony N
2011-11-01
Drivers' ability to react to unpredictable events deteriorates when exposed to highly predictable and uneventful driving tasks. Highway design reduces the driving task mainly to a lane-keeping manoeuvre. Such a task is monotonous, providing little stimulation and this contributes to crashes due to inattention. Research has shown that driver's hypovigilance can be assessed with EEG measurements and that driving performance is impaired during prolonged monotonous driving tasks. This paper aims to show that two dimensions of monotony - namely road design and road side variability - decrease vigilance and impair driving performance. This is the first study correlating hypovigilance and driver performance in varied monotonous conditions, particularly on a short time scale (a few seconds). We induced vigilance decrement as assessed with an EEG during a monotonous driving simulator experiment. Road monotony was varied through both road design and road side variability. The driver's decrease in vigilance occurred due to both road design and road scenery monotony and almost independently of the driver's sensation seeking level. Such impairment was also correlated to observable measurements from the driver, the car and the environment. During periods of hypovigilance, the driving performance impairment affected lane positioning, time to lane crossing, blink frequency, heart rate variability and non-specific electrodermal response rates. This work lays the foundation for the development of an in-vehicle device preventing hypovigilance crashes on monotonous roads.
Janchaysang, Suwatwong; Sumriddetchkajorn, Sarun; Buranasiri, Prathan
2013-06-01
We present the improved tunable filter based multispectral imaging system for detecting blood stains on construction materials. Based upon the reflectance and Kubelka Munk absorbance spectra stocked from our previous work, we modify the blood discrimination criteria to make the system more efficient by replacing the old criteria which make use of polynomial fitting with new criteria associated with a few wavelengths images. The newly established criteria are tested to be able to detect blood against other stains almost as efficient as the old criteria, while the number of spectral images required for detecting blood stains are reduced significantly from 64 to 9 spectral images. The reduction of required spectral images will reduce the time needed for image capturing and blood detection criteria application with little sacrificing of the specificity and sensitivity of the system.
D'Ulivo, Alessandro; Bramanti, Emilia; Lampugnani, Leonardo; Zamboni, Roberto
2001-10-01
The effects of tetrahydroborate and acid concentration and the presence of L-cysteine and thiourea were investigated in the determination of As, Bi and Sn using continuous flow hydride generation atomic fluorescence spectrometry (HG AFS). The aim was to find conditions allowing the control of those effects exerting negative influence on the analytical performance of the HG AFS apparatus. The effects taken into account were: (i) the radiation scattering generated by carryover of solution from the gas-liquid separator to the atomizer; (ii) the introduction of molecular species generated by tetrahydroborate decomposition into the atomizer; and (iii) interference effects arising from other elements in the sample matrix and from different acids. The effects (i) and (ii) could be controlled using mild reaction conditions in the HG stage. The effect of HG conditions on carryover was studied by radiation scattering experiments without hydride atomization. Compromised HG conditions were found by studying the effects of tetrahydroborate (0.1-20 g l -1) and acid (0.01-7 mol l -1) concentration, and the addition of L-cysteine (10 g l -1) and thiourea (0.1 mol l -1) on the HG AFS signals. The effect of optical filters was investigated with the aim of improving the signal-to-noise ratio. Optical filters with peak wavelengths of 190 and 220 nm provided an improvement of detection limits by factors of approximately 4 and 2 for As and Te, respectively. Under optimized conditions the detection limits were 6, 5, 3, 2, 2 and 9 ng l -1 for As, Sb, Bi, Sn, Se and Te, respectively. Good tolerance to various acid compositions and sample matrices was obtained by using L-cysteine or thiourea as masking agents. Determination of arsenic in sediment and copper certified reference materials, and of bismuth in steel, sediment, soil and ore certified reference material is reported.
Energy Technology Data Exchange (ETDEWEB)
Voncina, D.; Nastran, J.; Cajhen, R.; Nedeljkovic, D. [Ljubljana Univ. (Slovenia). Faculty of Electrical Engineering and Computer Science
1995-12-31
The parallel active power filter for nonlinear loads is described. First the method for extracting the fundamental active component from the load current, based on the combined analogue and digital signal processing is presented in detail. The load current is filtered by a precision analogue circuit. The phase and the amplitude of the load current fundamental component is passed to the microcontroller to calculate its active component. The implemented control principle provides fast response of the actual filter current. The results, obtained from the experimental circuit, illustrate the active filter`s performance in steady state and during load transients. 14 refs, 10 figs
Estimating monotonic rates from biological data using local linear regression.
Olito, Colin; White, Craig R; Marshall, Dustin J; Barneche, Diego R
2017-03-01
Accessing many fundamental questions in biology begins with empirical estimation of simple monotonic rates of underlying biological processes. Across a variety of disciplines, ranging from physiology to biogeochemistry, these rates are routinely estimated from non-linear and noisy time series data using linear regression and ad hoc manual truncation of non-linearities. Here, we introduce the R package LoLinR, a flexible toolkit to implement local linear regression techniques to objectively and reproducibly estimate monotonic biological rates from non-linear time series data, and demonstrate possible applications using metabolic rate data. LoLinR provides methods to easily and reliably estimate monotonic rates from time series data in a way that is statistically robust, facilitates reproducible research and is applicable to a wide variety of research disciplines in the biological sciences. © 2017. Published by The Company of Biologists Ltd.
Monotone traveling wavefronts of the KPP-Fisher delayed equation
Gomez, Adrian
2010-01-01
In the early 2000's, Gourley (2000), Wu et al. (2001), Ashwin et al. (2002) initiated the study of the positive wavefronts in the delayed Kolmogorov-Petrovskii-Piskunov-Fisher equation. Since then, this model has become one of the most popular objects in the studies of traveling waves for the monostable delayed reaction-diffusion equations. In this paper, we give a complete solution to the problem of existence and uniqueness of monotone waves in the KPP-Fisher equation. We show that each monotone traveling wave can be found via an iteration procedure. The proposed approach is based on the use of special monotone integral operators (which are different from the usual Wu-Zou operator) and appropriate upper and lower solutions associated to them. The analysis of the asymptotic expansions of the eventual traveling fronts at infinity is another key ingredient of our approach.
DEFF Research Database (Denmark)
Golestan, Saeed; Monfared, Mohammad; Frejeido, Francisco
2014-01-01
Control Parameters design of a three-phase synchronous reference frame phase locked loop (SRF-PLL) with a pre-filtering stage (acting as the sequence separator) is not a trivial task. The conventional way to deal with this problem is to neglect the interaction between the SRF-PLL and pre......-filtering stage, and treat them as two separate systems. This approach, although very simple, is not optimum as the pre-filtering stage and the SRF-PLL may have comparable dynamics. The aim of this paper is to develop a systematic and efficient approach to design the control parameters of a SRF-PLL with pre......-filtering stage. To this end, the paper first optimizes the performance of the filtering stage in detection of the sequence components. The paper then proceeds to reduce the interaction between the filtering stage and SRF-PLL, which is achieved by employing a derivative-filtered proportional...
Energy Technology Data Exchange (ETDEWEB)
Angelis, G I; Kotasidis, F A; Matthews, J C [Imaging, Proteomics and Genomics, MAHSC, University of Manchester, Wolfson Molecular Imaging Centre, Manchester (United Kingdom); Reader, A J [Montreal Neurological Institute, McGill University, Montreal (Canada); Lionheart, W R, E-mail: georgios.angelis@mmic.man.ac.uk [School of Mathematics, University of Manchester, Alan Turing Building, Manchester (United Kingdom)
2011-07-07
Iterative expectation maximization (EM) techniques have been extensively used to solve maximum likelihood (ML) problems in positron emission tomography (PET) image reconstruction. Although EM methods offer a robust approach to solving ML problems, they usually suffer from slow convergence rates. The ordered subsets EM (OSEM) algorithm provides significant improvements in the convergence rate, but it can cycle between estimates converging towards the ML solution of each subset. In contrast, gradient-based methods, such as the recently proposed non-monotonic maximum likelihood (NMML) and the more established preconditioned conjugate gradient (PCG), offer a globally convergent, yet equally fast, alternative to OSEM. Reported results showed that NMML provides faster convergence compared to OSEM; however, it has never been compared to other fast gradient-based methods, like PCG. Therefore, in this work we evaluate the performance of two gradient-based methods (NMML and PCG) and investigate their potential as an alternative to the fast and widely used OSEM. All algorithms were evaluated using 2D simulations, as well as a single [{sup 11}C]DASB clinical brain dataset. Results on simulated 2D data show that both PCG and NMML achieve orders of magnitude faster convergence to the ML solution compared to MLEM and exhibit comparable performance to OSEM. Equally fast performance is observed between OSEM and PCG for clinical 3D data, but NMML seems to perform poorly. However, with the addition of a preconditioner term to the gradient direction, the convergence behaviour of NMML can be substantially improved. Although PCG is a fast convergent algorithm, the use of a (bent) line search increases the complexity of the implementation, as well as the computational time involved per iteration. Contrary to previous reports, NMML offers no clear advantage over OSEM or PCG, for noisy PET data. Therefore, we conclude that there is little evidence to replace OSEM as the algorithm of choice
Monotone data visualization using rational trigonometric spline interpolation.
Ibraheem, Farheen; Hussain, Maria; Hussain, Malik Zawwar
2014-01-01
Rational cubic and bicubic trigonometric schemes are developed to conserve monotonicity of curve and surface data, respectively. The rational cubic function has four parameters in each subinterval, while the rational bicubic partially blended function has eight parameters in each rectangular patch. The monotonicity of curve and surface data is retained by developing constraints on some of these parameters in description of rational cubic and bicubic trigonometric functions. The remaining parameters are kept free to modify the shape of curve and surface if required. The developed algorithm is verified mathematically and demonstrated graphically.
Monotone Data Visualization Using Rational Trigonometric Spline Interpolation
Directory of Open Access Journals (Sweden)
Farheen Ibraheem
2014-01-01
Full Text Available Rational cubic and bicubic trigonometric schemes are developed to conserve monotonicity of curve and surface data, respectively. The rational cubic function has four parameters in each subinterval, while the rational bicubic partially blended function has eight parameters in each rectangular patch. The monotonicity of curve and surface data is retained by developing constraints on some of these parameters in description of rational cubic and bicubic trigonometric functions. The remaining parameters are kept free to modify the shape of curve and surface if required. The developed algorithm is verified mathematically and demonstrated graphically.
Ultimate generalization to monotonicity for uniform convergence of trigonometric series
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Chaundy and Jolliffe proved that if {a n } is a non-increasing (monotonic) real sequence with lim n →∞ a n = 0, then a necessary and sufficient condition for the uniform convergence of the series ∑∞ n=1 a n sin nx is lim n →∞ na n = 0. We generalize (or weaken) the monotonic condition on the coefficient sequence {a n } in this classical result to the so-called mean value bounded variation condition and prove that the generalized condition cannot be weakened further. We also establish an analogue to the generalized Chaundy-Jolliffe theorem in the complex space.
Vector optimization and monotone operators via convex duality recent advances
Grad, Sorin-Mihai
2014-01-01
This book investigates several duality approaches for vector optimization problems, while also comparing them. Special attention is paid to duality for linear vector optimization problems, for which a vector dual that avoids the shortcomings of the classical ones is proposed. Moreover, the book addresses different efficiency concepts for vector optimization problems. Among the problems that appear when the framework is generalized by considering set-valued functions, an increasing interest is generated by those involving monotone operators, especially now that new methods for approaching them by means of convex analysis have been developed. Following this path, the book provides several results on different properties of sums of monotone operators.
Directory of Open Access Journals (Sweden)
Chih-Chien Tsai
2014-03-01
Full Text Available This study develops a Doppler radar data assimilation system, which couples the local ensemble transform Kalman filter with the Weather Research and Forecasting model. The benefits of this system to quantitative precipitation nowcasting (QPN are evaluated with observing system simulation experiments on Typhoon Morakot (2009, which brought record-breaking rainfall and extensive damage to central and southern Taiwan. The results indicate that the assimilation of radial velocity and reflectivity observations improves the three-dimensional winds and rain-mixing ratio most significantly because of the direct relations in the observation operator. The patterns of spiral rainbands become more consistent between different ensemble members after radar data assimilation. The rainfall intensity and distribution during the 6-hour deterministic nowcast are also improved, especially for the first 3 hours. The nowcasts with and without radar data assimilation have similar evolution trends driven by synoptic-scale conditions. Furthermore, we carry out a series of sensitivity experiments to develop proper assimilation strategies, in which a mixed localisation method is proposed for the first time and found to give further QPN improvement in this typhoon case.
Denoising lidar signal by combining wavelet improved threshold with wavelet domain spatial filtering
Institute of Scientific and Technical Information of China (English)
Shirong Yin; Weiran Wang
2006-01-01
Lidar is an effective tool for remotely monitoring target or object, but the lidar signal is often affected by various noises or interferences. Therefore, detecting the weak signals buried in noises is a fundamental and important problem in the lidar systems. In this paper, an effective noise reduction method combining wavelet improved threshold with wavelet domain spatial filtration is presented to denoise pulse lidar signal and is investigated by detecting the simulating pulse lidar signals in noise. The simulation results show that this method can effectively identify the edge of signal and detect the weak lidar signal buried in noises.
Improving Photoacoustic-guided Focusing in Scattering Media by Spectrally Filtered Detection
Chaigne, Thomas; Gateau, Jérôme; Boccara, Claude; Gigan, Sylvain; Bossy, Emmanuel
2013-01-01
We experimentally and numerically study the potential of photoacoustic-guiding for light focusing through scattering samples via wavefront-shaping and iterative optimization. We experimentally demonstrate that the focusing efficiency on an extended absorber can be improved by iterative optimization of the high frequency components of the broadband photoacoustic signal detected with a spherically focused transducer. We demonstrate more than 8-fold increase in the photoacoustic signal generated by a 30 microns wire using a narrow frequency band around 60MHz. We numerically confirm that such optimization leads to a smaller optical focus than using the low frequency content of the photoacoustic feedback.
Improving the quality of the ECG signal by filtering in wavelet transform domain
DzierŻak, RóŻa; Surtel, Wojciech; Dzida, Grzegorz; Maciejewski, Marcin
2016-09-01
The article concerns the research methods of noise reduction occurring in the ECG signals. The method is based on the use of filtration in wavelet transform domain. The study was conducted on two types of signal - received during the rest of the patient and obtained during physical activity. For each of the signals 3 types of filtration were used. The study was designed to determine the effectiveness of various wavelets for de-noising signals obtained in both cases. The results confirm the suitability of the method for improving the quality of the electrocardiogram in case of both types of signals.
Energy Technology Data Exchange (ETDEWEB)
Härkönen, Emma, E-mail: emma.harkonen@helsinki.fi [Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland); Tervakangas, Sanna; Kolehmainen, Jukka [DIARC-Technology Inc., Espoo (Finland); Díaz, Belén; Światowska, Jolanta; Maurice, Vincent; Seyeux, Antoine; Marcus, Philippe [Laboratoire de Physico-Chimie des Surfaces, CNRS (UMR 7075) – Chimie ParisTech (ENSCP), F-75005 Paris (France); Fenker, Martin [FEM Research Institute, Precious Metals and Metals Chemistry, D-73525 Schwäbisch Gmünd (Germany); Tóth, Lajos; Radnóczi, György [Research Centre for Natural Sciences HAS, (MTA TKK), Budapest (Hungary); Ritala, Mikko [Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland)
2014-10-15
Sublayers grown with filtered cathodic arc deposition (FCAD) were added under atomic layer deposited (ALD) oxide coatings for interface control and improved corrosion protection of low alloy steel. The FCAD sublayer was either Ta:O or Cr:O–Ta:O nanolaminate, and the ALD layer was Al{sub 2}O{sub 3}–Ta{sub 2}O{sub 5} nanolaminate, Al{sub x}Ta{sub y}O{sub z} mixture or graded mixture. The total thicknesses of the FCAD/ALD duplex coatings were between 65 and 120 nm. Thorough analysis of the coatings was conducted to gain insight into the influence of the FCAD sublayer on the overall coating performance. Similar characteristics as with single FCAD and ALD coatings on steel were found in the morphology and composition of the duplex coatings. However, the FCAD process allowed better control of the interface with the steel by reducing the native oxide and preventing its regrowth during the initial stages of the ALD process. Residual hydrocarbon impurities were buried in the interface between the FCAD layer and steel. This enabled growth of ALD layers with improved electrochemical sealing properties, inhibiting the development of localized corrosion by pitting during immersion in acidic NaCl and enhancing durability in neutral salt spray testing. - Highlights: • Corrosion protection properties of ALD coatings were improved by FCAD sublayers. • The FCAD sublayer enabled control of the coating-substrate interface. • The duplex coatings offered improved sealing properties and durability in NSS. • The protective properties were maintained during immersion in a corrosive solution. • The improvements were due to a more ideal ALD growth on the homogeneous FCAD oxide.
Directory of Open Access Journals (Sweden)
Xiaoming Xi
2013-07-01
Full Text Available Retinal identification based on retinal vasculatures in the retina provides the most secure and accurate means of authentication among biometrics and has primarily been used in combination with access control systems at high security facilities. Recently, there has been much interest in retina identification. As digital retina images always suffer from deformations, the Scale Invariant Feature Transform (SIFT, which is known for its distinctiveness and invariance for scale and rotation, has been introduced to retinal based identification. However, some shortcomings like the difficulty of feature extraction and mismatching exist in SIFT-based identification. To solve these problems, a novel preprocessing method based on the Improved Circular Gabor Transform (ICGF is proposed. After further processing by the iterated spatial anisotropic smooth method, the number of uninformative SIFT keypoints is decreased dramatically. Tested on the VARIA and eight simulated retina databases combining rotation and scaling, the developed method presents promising results and shows robustness to rotations and scale changes.
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Accurate assignment of model and observation errors is crucial for the successful application of land surface data assimilation algorithms. Poorly-specified model and observation errors can significantly degrade assimilation results. In 2008, Reichle et al. developed an operational procedure to adaptively tune model and observation errors. In this paper, we modified and applied Reichle’s procedure in the Noah land surface model to assimilate observed surface soil moisture data. Numerical simulations showed that: (1) the best estimate of model and observation errors appears when the empirical factor β equals 1.02; (2) the Reichle procedure can be deployed to adaptively tune errors if their true values change slowly; and (3) convergence of the Reichle procedure was improved using better initial errors achieved by iterative computations.
Institute of Scientific and Technical Information of China (English)
寿春晖; 骆仲泱; 王涛; 沈伟东; ROSENGARTEN Gary; 王诚; 倪明江; 岑可法
2011-01-01
In this Letter we outline a dielectric multilayer spectrally selective filter designed for solar energy applications. The optical performance of this 78-layer interference filter constructed by TiOx and SiO2 is presented. A hybrid system combining photovoltaic cells with a solar-powered Stirling engine using the designed filter is analyzed. The calculated results show the advantages of this spectrally selective method for solar power generation.%In this Letter we outline a dielectric multilayer spectrally selective filter designed for solar energy applications.The optical performance of this 78-layer interference filter constructed by TiOx and SiO2 is presented.A hybrid system combining photovoltaic cells with a solar-powered Stirling engine using the designed filter is analyzed.The calculated results show the advantages of this spectrally selective method for solar power generation.
DEFF Research Database (Denmark)
Sanchez-Reales, J. M.; Andersen, Ole Baltazar; Vigo, M. I.
2016-01-01
in the Northwestern Pacific Ocean, we found that EED filtering provides similar estimation of the current velocities in both cases, whereas a non-linear isotropic filter (the Perona and Malik filter) returns results influenced by local residual noise when a difficult case is tested. We found that EED filtering......With increased geoid resolution provided by the gravity and steady-state ocean circulation explorer (GOCE) mission, the ocean's mean dynamic topography (MDT) can be now estimated with an accuracy not available prior to using geodetic methods. However, an altimetric-derived MDT still needs filtering...... in order to remove short wavelength noise unless integrated methods are used in which the three quantities are determined simultaneously using appropriate covariance functions. We studied nonlinear anisotropic diffusive filtering applied to the oceanA ' s MDT and a new approach based on edge...
MONOTONE ITERATION FOR ELLIPTIC PDEs WITH DISCONTINUOUS NONLINEAR TERMS
Institute of Scientific and Technical Information of China (English)
Zou Qingsong
2005-01-01
In this paper, we use monotone iterative techniques to show the existence of maximal or minimal solutions of some elliptic PDEs with nonlinear discontinuous terms. As the numerical analysis of this PDEs is concerned, we prove the convergence of discrete extremal solutions.
Modeling non-monotone risk aversion using SAHARA utility functions
A. Chen; A. Pelsser; M. Vellekoop
2011-01-01
We develop a new class of utility functions, SAHARA utility, with the distinguishing feature that it allows absolute risk aversion to be non-monotone and implements the assumption that agents may become less risk averse for very low values of wealth. The class contains the well-known exponential and
On Uniqueness of Conjugacy of Continuous and Piecewise Monotone Functions
Directory of Open Access Journals (Sweden)
Ciepliński Krzysztof
2009-01-01
Full Text Available We investigate the existence and uniqueness of solutions of the functional equation , , where are closed intervals, and , are some continuous piecewise monotone functions. A fixed point principle plays a crucial role in the proof of our main result.
L^p solutions of reflected BSDEs under monotonicity condition
Rozkosz, Andrzej
2012-01-01
We prove existence and uniqueness of L^p solutions of reflected backward stochastic differential equations with p-integrable data and generators satisfying the monotonicity condition. We also show that the solution may be approximated by the penalization method. Our results are new even in the classical case p=2.
A monotonic method for solving nonlinear optimal control problems
Salomon, Julien
2009-01-01
Initially introduced in the framework of quantum control, the so-called monotonic algorithms have shown excellent numerical results when dealing with various bilinear optimal control problems. This paper aims at presenting a unified formulation of such procedures and the intrinsic assumptions they require. In this framework, we prove the feasibility of the general algorithm. Finally, we explain how these assumptions can be relaxed.
On Some Conjectures on the Monotonicity of Some Arithmetical Sequences
2012-01-01
THE MONOTONICITY OF SOME ARITHMETICAL SEQUENCES ∗ Florian Luca † Centro de Ciencias Matemáticas, Universidad Nacional Autonoma de México, C.P. 58089...visit of P. S. to the Centro de Ciencias Matemáticas de la UNAM in Morelia in August 2012. During the preparation of this paper, F. L. was supported in
Interval Routing and Minor-Monotone Graph Parameters
Bakker, E.M.; Bodlaender, H.L.; Tan, R.B.; Leeuwen, J. van
2006-01-01
We survey a number of minor-monotone graph parameters and their relationship to the complexity of routing on graphs. In particular we compare the interval routing parameters κslir(G) and κsir(G) with Colin de Verdi`ere’s graph invariant μ(G) and its variants λ(G) and κ(G). We show that for all the k
Multivariate Regression with Monotone Missing Observation of the Dependent Variables
Raats, V.M.; van der Genugten, B.B.; Moors, J.J.A.
2002-01-01
Multivariate regression is discussed, where the observations of the dependent variables are (monotone) missing completely at random; the explanatory variables are assumed to be completely observed.We discuss OLS-, GLS- and a certain form of E(stimated) GLS-estimation.It turns out that
Minimum Cost Spanning Tree Games and Population Monotonic Allocation Schemes
Norde, H.W.; Moretti, S.; Tijs, S.H.
2001-01-01
In this paper we present the Subtraction Algorithm that computes for every classical minimum cost spanning tree game a population monotonic allocation scheme.As a basis for this algorithm serves a decomposition theorem that shows that every minimum cost spanning tree game can be written as nonnegati
Size monotonicity and stability of the core in hedonic games
Dimitrov, Dinko; Sung, Shao Chin
2011-01-01
We show that the core of each strongly size monotonic hedonic game is not empty and is externally stable. This is in sharp contrast to other sufficient conditions for core non-emptiness which do not even guarantee the existence of a stable set in such games.
Monotone missing data and repeated controls of fallible authors
Raats, V.M.
2004-01-01
Chapters 2 and 3 focus on repeated audit controls with categorical variables. Chapter 4 and 5 introduce and analyse a very general multivariate regression model for (monotone) missing data. In the final Chapter 6 the previous chapters are combined into a more realistic model for repeated audit contr
A POTENTIAL REDUCTION ALGORITHM FOR MONOTONE VARIATIONAL INEQUALITY PROBLEMS
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
A potential reduction algorithm is proposed for the solution of monotone variational inequality problems. At each step of the algorithm, a system of linear equations is solved to get the search direction and the Armijo's rule is used to determine the stepsize.It is proved that the algorithm is globally convergent. Computational results are reported.
Relaxing monotonicity in the identification of local average treatment effects
DEFF Research Database (Denmark)
Huber, Martin; Mellace, Giovanni
In heterogeneous treatment effect models with endogeneity, the identification of the local average treatment effect (LATE) typically relies on an instrument that satisfies two conditions: (i) joint independence of the potential post-instrument variables and the instrument and (ii) monotonicity...
Incorporating "Unconscious Reanalysis" into an Incremental, Monotonic Parser
Sturt, P
1995-01-01
This paper describes an implementation based on a recent model in the psycholinguistic literature. We define a parsing operation which allows the reanalysis of dependencies within an incremental and monotonic processing architecture, and discuss search strategies for its application in a head-initial language (English) and a head-final language (Japanese).
Interval Routing and Minor-Monotone Graph Parameters
Bakker, E.M.; Bodlaender, H.L.; Tan, R.B.; Leeuwen, J. van
2006-01-01
We survey a number of minor-monotone graph parameters and their relationship to the complexity of routing on graphs. In particular we compare the interval routing parameters κslir(G) and κsir(G) with Colin de Verdi`ere’s graph invariant μ(G) and its variants λ(G) and κ(G). We show that for all the
Reasoning Biases, Non-Monotonic Logics, and Belief Revision
Dutilh Novaes, Catarina; Veluwenkamp, Herman
2017-01-01
A range of formal models of human reasoning have been proposed in a number of fields such as philosophy, logic, artificial intelligence, computer science, psychology, cognitive science etc.: various logics (epistemic logics; non-monotonic logics), probabilistic systems (most notably, but not exclusi
Shou, Chun-Hui; Luo, Zhong-Yang; Wang, Tao; Shen, Wei-Dong; Rosengarten, Gary; Wang, Cheng; Ni, Ming-Jiang; Cen, Ke-Fa
2011-12-01
In this Letter we outline a dielectric multilayer spectrally selective filter designed for solar energy applications. The optical performance of this 78-layer interference filter constructed by TiOx and SiO2 is presented. A hybrid system combining photovoltaic cells with a solar-powered Stirling engine using the designed filter is analyzed. The calculated results show the advantages of this spectrally selective method for solar power generation.
Directory of Open Access Journals (Sweden)
Kriengsak Wattanawitoon
2011-01-01
Full Text Available We prove strong and weak convergence theorems of modified hybrid proximal-point algorithms for finding a common element of the zero point of a maximal monotone operator, the set of solutions of equilibrium problems, and the set of solution of the variational inequality operators of an inverse strongly monotone in a Banach space under different conditions. Moreover, applications to complementarity problems are given. Our results modify and improve the recently announced ones by Li and Song (2008 and many authors.
Institute of Scientific and Technical Information of China (English)
Xie-ping DING; Zhong-bao WANG
2009-01-01
A new system of the set-valued mixed quasi-variational-like inclusions (SS-MQVLI) involving H-η-monotone operators is studied in general Banach spaces without uniform smoothness. By using the resolvent operator technique of H-η-monotone opera-tors, a new iterative algorithm for finding approximate solutions to SSMQVLI is proposed. It is shown that the iterative sequences generated by the algorithm converge strongly to the exact solution of SSMQVLI under appropriate assumptions. These obtained new re-sults have extended and improved previous results.
Mihai, Georgeta; Ding, Yu; Xue, Hui; Chung, Yiu-Cho; Rajagopalan, Sanjay; Guehring, Jens; Simonetti, Orlando P
2012-12-01
The purpose of the study was to evaluate the effect of motion compensation by non-rigid registration combined with the Karhunen-Loeve Transform (KLT) filter on the signal to noise (SNR) and contrast-to-noise ratio (CNR) of hybrid gradient-echo echoplanar (GRE-EPI) first-pass myocardial perfusion imaging. Twenty one consecutive first-pass adenosine stress perfusion MR data sets interpreted positive for ischemia or infarction were processed by non-rigid Registration followed by KLT filtering. SNR and CNR were measured in abnormal and normal myocardium in unfiltered and KLT filtered images following non-rigid registration to compensate for respiratory and other motions. Image artifacts introduced by filtering in registered and nonregistered images were evaluated by two observers. There was a statistically significant increase in both SNR and CNR between normal and abnormal myocardium with KLT filtering (mean SNR increased by 62.18% ± 21.05% and mean CNR increased by 58.84% ± 18.06%; p = 0.01). Motion correction prior to KLT filtering reduced significantly the occurrence of filter induced artifacts (KLT only-artifacts in 42 out of 55 image series vs. registered plus KLT-artifacts in 3 out of 55 image series). In conclusion the combination of non- rigid registration and KLT filtering was shown to increase the SNR and CNR of GRE-EPI perfusion images. Subjective evaluation of image artifacts revealed that prior motion compensation significantly reduced the artifacts introduced by the KLT filtering process.
Directory of Open Access Journals (Sweden)
Marwa Ben Said-Romdhane
2017-03-01
Full Text Available With the smart grid revolution, there is a growing interest in the use of power converters associated to LCL filters to interface between the main utility grid and loads or renewable energy sources. LCL filters are commonly used mainly due to their low cost and high filtering performances. To achieve these performances, it is necessary to meticulously pick out the LCL filter parameters, taking into account grid code requirements and grid configuration and/or conditions. Several methodologies for LCL filter design have been presented and discussed in the literature. The main goal of this paper is to propose a simple, robust and systematic design methodology for LCL filter parameter tuning. The considered design methodology is aimed to overcome the shortcomings of classical design methodologies, namely, stable operation under different grid configurations and conditions. Compared to previous works, the proposed design methodology allows the achievement of robust LCL filter design with regard to large grid impedance variations without the use of any damping method. Also, it takes into account accuracy of capacitor standard values and proposes a simple design method for the converter side inductor that avoids saturation problems. An example of LCL filter design is presented and discussed. The obtained filter parameters were firstly tested using a Matlab-Simulink software tool. After that, they were tested through the development of an experimental set-up. The obtained simulation and experimental results show the reliability and efficiency of the proposed design methodology.
Xu, X.
2016-12-01
The uncertainty associated with inflow boundary forcing data has been recognized as an important and dominant source of uncertainties in hydraulic model. Here, we develop a real-time probabilistic channel flood forecasting model with a novel function to incorporate the uncertainty of forcing inflow. This new approach couples a hydraulic model with the Sequential Monte Carlo (SMC), Particle filter (PF), data assimilation algorithm. Stage observations at hydrological stations along the channel are assimilated at each time step to update the model states in order to improve next time step's forecasting. We test this new approach for a real flood event occurred during June 27, 2009 and July 9, 2009 in the river reach from upstream Cuntan station to downstream Zhongxian station of the Middle Yangtze River, China. As compared with open loop model simulations, model evaluations with several quantitative deterministic and probabilistic metrics indicate that accuracy of the ensemble mean prediction and reliability of the uncertainty quantification are improved pronouncedly as a result of the PF assimilation. Further assessment of forecasting performance at different lead times shows that the degree of model improvement weakens with the increase of lead time due to the gradual diminishing of updating effect on initial conditions. The examination of different number of particles shows that the optimal number of particles can be chosen as a tradeoff between model performance and computation burden. The analysis of different assimilation frequency indicates that higher assimilation frequency can help improve the model performance by incorporating more observation information and updating model states to better represent instantaneous flood conditions.
Silvani, M. I.; Almeida, G. L.; Latini, R. M.; Bellido, A. V. B.; Souza, E. S.; Lopes, R. T.
2015-07-01
Earlier works have shown the feasibility to correct the deformation of the attenuation map in radiographs acquired with conical radiation beams provided that the inspected object could be expressed into analytical geometry terms. This correction reduces the contribution of the main object in the radiograph, allowing thus the visualization of its otherwise concealed heterogeneities. However, the non-punctual character of the source demanded a cumbersome trial-and-error approach in order to determine the proper correction parameters for the algorithm. Within this frame, this work addresses the improvement of radiographs of specially tailored test-objects acquired with a conical beam through correction of its divergence by using the information contained in the image itself. The corrected images have afterwards undergone a filtration in the frequency domain aiming at the reduction of statistical fluctuation and noise by using a 2D Fourier transform. All radiographs have been acquired using 165Dy and 198Au gamma-ray sources produced at the Argonauta research reactor in Institutode Engenharia Nuclear - CNEN, and an X-ray sensitive imaging plate as detector. The processed images exhibit features otherwise invisible in the original ones. Their processing by conventional histogram equalization carried out for comparison purposes did not succeed to detect those features.
Stok, Wim J; Westerhof, Berend E; Guelen, Ilja; Karemaker, John M
2011-08-01
Reconstruction of central aortic pressure from a peripheral measurement by a generalized transfer function (genTF) works well at rest and mild exercise at lower heart rates, but becomes less accurate during heavy exercise. Particularly, systolic and pulse pressure estimations deteriorate, thereby underestimating central pressure. We tested individualization of the TF (indTF) by adapting its resonance frequency at the various levels of exercise. In seven males (age 44-57) with coronary artery disease, central and peripheral pressures were measured simultaneously. The optimal resonance frequency was predicted from regression formulas using variables derived from the individual's peripheral pressure pulse, including a pulse contour estimation of cardiac output (pcCO). In addition, reconstructed pressures were calibrated to central mean and diastolic pressure at each exercise level. Using a genTF and without calibration, the error in estimated aortic pulse pressure was -7.5 ± 6.4 mmHg, which was reduced to 0.2 ± 5.7 mmHg with the indTFs using pcCO for prediction. Calibration resulted in less scatter at the cost of a small bias (2.7 mmHg). In exercise, the indTFs predict systolic and pulse pressure better than the genTF. This pilot study shows that it is possible to individualize the peripheral to aortic pressure transfer function, thereby improving accuracy in central blood pressure assessment during exercise.
Kakakhel, M B; Jirasek, A; Johnston, H; Kairn, T; Trapp, J V
2017-02-06
This study evaluated the feasibility of combining the 'zero-scan' (ZS) X-ray computed tomography (CT) based polymer gel dosimeter (PGD) readout with adaptive mean (AM) filtering for improving the signal to noise ratio (SNR), and to compare these results with available average scan (AS) X-ray CT readout techniques. NIPAM PGD were manufactured, irradiated with 6 MV photons, CT imaged and processed in Matlab. AM filter for two iterations, with 3 × 3 and 5 × 5 pixels (kernel size), was used in two scenarios (a) the CT images were subjected to AM filtering (pre-processing) and these were further employed to generate AS and ZS gel images, and (b) the AS and ZS images were first reconstructed from the CT images and then AM filtering was carried out (post-processing). SNR was computed in an ROI of 30 × 30 for different pre and post processing cases. Results showed that the ZS technique combined with AM filtering resulted in improved SNR. Using the previously-recommended 25 images for reconstruction the ZS pre-processed protocol can give an increase of 44% and 80% in SNR for 3 × 3 and 5 × 5 kernel sizes respectively. However, post processing using both techniques and filter sizes introduced blur and a reduction in the spatial resolution. Based on this work, it is possible to recommend that the ZS method may be combined with pre-processed AM filtering using appropriate kernel size, to produce a large increase in the SNR of the reconstructed PGD images.
Non-monotonic effect of confinement on the glass transition
Varnik, Fathollah; Franosch, Thomas
2016-04-01
The relaxation dynamics of glass forming liquids and their structure are influenced in the vicinity of confining walls. This effect has mostly been observed to be a monotonic function of the slit width. Recently, a qualitatively new behaviour has been uncovered by Mittal and coworkers, who reported that the single particle dynamics in a hard-sphere fluid confined in a planar slit varies in a non-monotonic way as the slit width is decreased from five to roughly two particle diametres (Mittal et al 2008 Phys. Rev. Lett. 100 145901). In view of the great potential of this effect for applications in those fields of science and industry, where liquids occur under strong confinement (e.g. nano-technology), the number of researchers studying various aspects and consequences of this non-monotonic behaviour has been rapidly growing. This review aims at providing an overview of the research activity in this newly emerging field. We first briefly discuss how competing mechanisms such as packing effects and short-range attraction may lead to a non-monotonic glass transition scenario in the bulk. We then analyse confinement effects on the dynamics of fluids using a thermodynamic route which relates the single particle dynamics to the excess entropy. Moreover, relating the diffusive dynamics to the Widom’s insertion probability, the oscillations of the local dynamics with density at moderate densities are fairly well described. At high densities belonging to the supercooled regime, however, this approach breaks down signaling the onset of strongly collective effects. Indeed, confinement introduces a new length scale which in the limit of high densities and small pore sizes competes with the short-range local order of the fluid. This gives rise to a non-monotonic dependence of the packing structure on confinement, with a corresponding effect on the dynamics of structural relaxation. This non-monotonic effect occurs also in the case of a cone-plate type channel, where the degree
Lim, Hansaim; Gray, Paul; Xie, Lei; Poleksic, Aleksandar
2016-12-01
Conventional one-drug-one-gene approach has been of limited success in modern drug discovery. Polypharmacology, which focuses on searching for multi-targeted drugs to perturb disease-causing networks instead of designing selective ligands to target individual proteins, has emerged as a new drug discovery paradigm. Although many methods for single-target virtual screening have been developed to improve the efficiency of drug discovery, few of these algorithms are designed for polypharmacology. Here, we present a novel theoretical framework and a corresponding algorithm for genome-scale multi-target virtual screening based on the one-class collaborative filtering technique. Our method overcomes the sparseness of the protein-chemical interaction data by means of interaction matrix weighting and dual regularization from both chemicals and proteins. While the statistical foundation behind our method is general enough to encompass genome-wide drug off-target prediction, the program is specifically tailored to find protein targets for new chemicals with little to no available interaction data. We extensively evaluate our method using a number of the most widely accepted gene-specific and cross-gene family benchmarks and demonstrate that our method outperforms other state-of-the-art algorithms for predicting the interaction of new chemicals with multiple proteins. Thus, the proposed algorithm may provide a powerful tool for multi-target drug design.
Mousavi Anzehaee, Mohammad; Adib, Ahmad; Heydarzadeh, Kobra
2015-10-01
The manner of microtremor data collection and filtering operation and also the method used for processing have a considerable effect on the accuracy of estimation of dynamic soil parameters. In this paper, running variance method was used to improve the automatic detection of data sections infected by local perturbations. In this method, the microtremor data running variance is computed using a sliding window. Then the obtained signal is used to remove the ranges of data affected by perturbations from the original data. Additionally, to determinate the fundamental frequency of a site, this study has proposed a statistical characteristics-based method. Actually, statistical characteristics, such as the probability density graph and the average and the standard deviation of all the frequencies corresponding to the maximum peaks in the H/ V spectra of all data windows, are used to differentiate the real peaks from the false peaks resulting from perturbations. The methods have been applied to the data recorded for the City of Meybod in central Iran. Experimental results show that the applied methods are able to successfully reduce the effects of extensive local perturbations on microtremor data and eventually to estimate the fundamental frequency more accurately compared to other common methods.
Wang, Cheng; He, Yue; Lu, Bin; Jiang, Jun; Miao, Li; Deng, Xian-Jin; Xiong, Yong-zhong; Zhang, Jian
2017-09-01
This paper presents a sub-harmonic mixer at 340 GHz based on anti-parallel Schottky diodes (SBDs). Intrinsic resonances in low-pass hammer-head filter have been adopted to enhance the isolation for different harmonic components, while greatly minimizing the transmission loss. The application of new DC grounding structure, impedance matching structure, and suspended micro-strip mitigates the negative influences of fabrication errors from metal cavity, quartz substrate, and micro-assembly. An improved lumped element equivalent circuit model of SBDs guarantees the accuracy of simulation, which takes current-voltage (I/V) behavior, capacitance-voltage (C/V) behavior, carrier velocity saturation, DC series resistor, plasma resonance, skin effect, and four kinds of noise generation mechanisms into consideration thoroughly. The measurement indicates that with local oscillating signal of 2 mW, the lowest double sideband conversion loss is 5.5 dB at 339 GHz; the corresponding DSB noise temperature is 757 K. The 3 dB bandwidth of conversion loss is 50 GHz from 317 to 367 GHz.
Directory of Open Access Journals (Sweden)
Ines Baccouche
2017-05-01
Full Text Available Accurate modeling of the nonlinear relationship between the open circuit voltage (OCV and the state of charge (SOC is required for adaptive SOC estimation during the lithium-ion (Li-ion battery operation. Online SOC estimation should meet several constraints, such as the computational cost, the number of parameters, as well as the accuracy of the model. In this paper, these challenges are considered by proposing an improved simplified and accurate OCV model of a nickel manganese cobalt (NMC Li-ion battery, based on an empirical analytical characterization approach. In fact, composed of double exponential and simple quadratic functions containing only five parameters, the proposed model accurately follows the experimental curve with a minor fitting error of 1 mV. The model is also valid at a wide temperature range and takes into account the voltage hysteresis of the OCV. Using this model in SOC estimation by the extended Kalman filter (EKF contributes to minimizing the execution time and to reducing the SOC estimation error to only 3% compared to other existing models where the estimation error is about 5%. Experiments are also performed to prove that the proposed OCV model incorporated in the EKF estimator exhibits good reliability and precision under various loading profiles and temperatures.
Directory of Open Access Journals (Sweden)
Jian Wang
2015-11-01
Full Text Available In this paper, a scheme is presented for fusing a foot-mounted Inertial Measurement Unit (IMU and a floor map to provide ubiquitous positioning in a number of settings, such as in a supermarket as a shopping guide, in a fire emergency service for navigation, or with a hospital patient to be tracked. First, several Zero-Velocity Detection (ZDET algorithms are compared and discussed when used in the static detection of a pedestrian. By introducing information on the Zero Velocity of the pedestrian, fused with a magnetometer measurement, an improved Pedestrian Dead Reckoning (PDR model is developed to constrain the accumulating errors associated with the PDR positioning. Second, a Correlation Matching Algorithm based on map projection (CMAP is presented, and a zone division of a floor map is demonstrated for fusion of the PDR algorithm. Finally, in order to use the dynamic characteristics of a pedestrian’s trajectory, the Adaptive Unscented Kalman Filter (A-UKF is applied to tightly integrate the IMU, magnetometers and floor map for ubiquitous positioning. The results of a field experiment performed on the fourth floor of the School of Environmental Science and Spatial Informatics (SESSI building on the China University of Mining and Technology (CUMT campus confirm that the proposed scheme can reliably achieve meter-level positioning.
Institute of Scientific and Technical Information of China (English)
Binbin He
2007-01-01
A simple data assimilation method for improving estimation of moderate resolution imaging spectroradiometer (MODIS) leaf area index (LAI) time-series data products based on the gradient inverse weighted filter and object analysis is proposed. The properties and quality control (QC) of MODIS LAI data products are introduced. Also, the gradient inverse weighted filter and object analysis are analyzed. An experiment based on the simple data assimilation method is performed using MODIS LAI data sets from 2000 to 2005 of Guizhou Province in China.
Directory of Open Access Journals (Sweden)
A. P. Tran
2013-07-01
Full Text Available The vertical profile of shallow unsaturated zone soil moisture plays a key role in many hydro-meteorological and agricultural applications. We propose a closed-loop data assimilation procedure based on the maximum likelihood ensemble filter algorithm to update the vertical soil moisture profile from time-lapse ground-penetrating radar (GPR data. A hydrodynamic model is used to propagate the system state in time and a radar electromagnetic model and petrophysical relationships to link the state variable with the observation data, which enables us to directly assimilate the GPR data. Instead of using the surface soil moisture only, the approach allows to use the information of the whole soil moisture profile for the assimilation. We validated our approach through a synthetic study. We constructed a synthetic soil column with a depth of 80 cm and analyzed the effects of the soil type on the data assimilation by considering 3 soil types, namely, loamy sand, silt and clay. The assimilation of GPR data was performed to solve the problem of unknown initial conditions. The numerical soil moisture profiles generated by the Hydrus-1D model were used by the GPR model to produce the "observed" GPR data. The results show that the soil moisture profile obtained by assimilating the GPR data is much better than that of an open-loop forecast. Compared to the loamy sand and silt, the updated soil moisture profile of the clay soil converges to the true state much more slowly. Decreasing the update interval from 60 down to 10 h only slightly improves the effectiveness of the GPR data assimilation for the loamy sand but significantly for the clay soil. The proposed approach appears to be promising to improve real-time prediction of the soil moisture profiles as well as to provide effective estimates of the unsaturated hydraulic properties at the field scale from time-lapse GPR measurements.
Hartman, Brian Davis
1995-01-01
resolution of solutions obtained from standard sequential filtering methods and process noise sequential filtering methods shows that the accuracy is significantly improved using process noise. The results show that the positional accuracy of the orbit is improved as well. The temporal resolution of the resulting solutions are detailed, and conclusions drawn about the results. Benefits and drawbacks of using process noise filtering in this type of scenario are also identified.
A Hybrid Approach to Proving Memory Reference Monotonicity
Oancea, Cosmin E.
2013-01-01
Array references indexed by non-linear expressions or subscript arrays represent a major obstacle to compiler analysis and to automatic parallelization. Most previous proposed solutions either enhance the static analysis repertoire to recognize more patterns, to infer array-value properties, and to refine the mathematical support, or apply expensive run time analysis of memory reference traces to disambiguate these accesses. This paper presents an automated solution based on static construction of access summaries, in which the reference non-linearity problem can be solved for a large number of reference patterns by extracting arbitrarily-shaped predicates that can (in)validate the reference monotonicity property and thus (dis)prove loop independence. Experiments on six benchmarks show that our general technique for dynamic validation of the monotonicity property can cover a large class of codes, incurs minimal run-time overhead and obtains good speedups. © 2013 Springer-Verlag.
Measurement of non-monotonic Casimir forces between silicon nanostructures
Tang, L.; Wang, M.; Ng, C. Y.; Nikolic, M.; Chan, C. T.; Rodriguez, A. W.; Chan, H. B.
2017-01-01
Casimir forces are of fundamental interest because they originate from quantum fluctuations of the electromagnetic field. Apart from controlling this force via the optical properties of materials, a number of novel geometries have been proposed to generate repulsive and/or non-monotonic Casimir forces between bodies separated by vacuum gaps. Experimental realization of these geometries, however, is hindered by the difficulties in alignment when the bodies are brought into close proximity. Here, using an on-chip platform with integrated force sensors and actuators, we circumvent the alignment problem and measure the Casimir force between two surfaces with nanoscale protrusions. We demonstrate that the force depends non-monotonically on the displacement. At some displacements, the Casimir force leads to an effective stiffening of the nanomechanical spring. Our findings pave the way for exploiting the Casimir force in nanomechanical systems using structures of complex and non-conventional shapes.
Computation of Optimal Monotonicity Preserving General Linear Methods
Ketcheson, David I.
2009-07-01
Monotonicity preserving numerical methods for ordinary differential equations prevent the growth of propagated errors and preserve convex boundedness properties of the solution. We formulate the problem of finding optimal monotonicity preserving general linear methods for linear autonomous equations, and propose an efficient algorithm for its solution. This algorithm reliably finds optimal methods even among classes involving very high order accuracy and that use many steps and/or stages. The optimality of some recently proposed methods is verified, and many more efficient methods are found. We use similar algorithms to find optimal strong stability preserving linear multistep methods of both explicit and implicit type, including methods for hyperbolic PDEs that use downwind-biased operators.
Rational functions with maximal radius of absolute monotonicity
Loczi, Lajos
2014-05-19
We study the radius of absolute monotonicity R of rational functions with numerator and denominator of degree s that approximate the exponential function to order p. Such functions arise in the application of implicit s-stage, order p Runge-Kutta methods for initial value problems and the radius of absolute monotonicity governs the numerical preservation of properties like positivity and maximum-norm contractivity. We construct a function with p=2 and R>2s, disproving a conjecture of van de Griend and Kraaijevanger. We determine the maximum attainable radius for functions in several one-parameter families of rational functions. Moreover, we prove earlier conjectured optimal radii in some families with 2 or 3 parameters via uniqueness arguments for systems of polynomial inequalities. Our results also prove the optimality of some strong stability preserving implicit and singly diagonally implicit Runge-Kutta methods. Whereas previous results in this area were primarily numerical, we give all constants as exact algebraic numbers.
DEFF Research Database (Denmark)
Lu, Minghui; Xin, Zhen; Wang, Xiongfei;
2016-01-01
For the LCL-filtered grid-connected inverter, it has been reported that the digital time delays will narrow the stable region of current control loop when the inverter-side current is used for implementing the feedback control. A sufficient stable condition is that the filter resonance frequency....... Theoretical analysis is then provided to validate its feasibility and stability. Compared to other widely used active damping strategies, no extra sensors are needed because the filter capacitor voltage, which is used for voltage feedforward control, is also sampled for phase-locked loop in this paper...
DSP Control of Line Hybrid Active Filter
DEFF Research Database (Denmark)
Dan, Stan George; Benjamin, Doniga Daniel; Magureanu, R.;
2005-01-01
Active Power Filters have been intensively explored in the past decade. Hybrid active filters inherit the efficiency of passive filters and the improved performance of active filters, and thus constitute a viable improved approach for harmonic compensation. In this paper a parallel hybrid filter ...
On Uniqueness of Conjugacy of Continuous and Piecewise Monotone Functions
Directory of Open Access Journals (Sweden)
Krzysztof Ciepliński
2009-01-01
Full Text Available We investigate the existence and uniqueness of solutions φ:I→J of the functional equation φ(f(x=F(φ(x, x∈I, where I,J are closed intervals, and f:I→I, F:J→J are some continuous piecewise monotone functions. A fixed point principle plays a crucial role in the proof of our main result.
Block Monotone Iterative Algorithms for Variational Inequalities with Nonlinear Operators
Institute of Scientific and Technical Information of China (English)
Ming-hui Ren; Jin-ping Zeng
2008-01-01
Some block iterative methods for solving variational inequalities with nonlinear operators are proposed. Monotone convergence of the algorithms is obtained. Some comparison theorems are also established.Compared with the research work in given by Pao in 1995 for nonlinear equations and research work in given by Zeng and Zhou in 2002 for elliptic variational inequalities, the algorithms proposed in this paper are independent of the boundedness of the derivatives of the nonlinear operator.
Monotonic Property in Field Algebra of G-Spin Model
Institute of Scientific and Technical Information of China (English)
蒋立宁
2003-01-01
Let F be the field algebra of G-spin model, D(G) the double algebra of a finite group G and D(H) the sub-Hopf algerba of D(G) determined by the subgroup H of G. The paper builds a correspondence between D(H) and the D(H)-invariant sub-C*-algebra AH in F, and proves that the correspondence is strictly monotonic.
Modeling argumentation based semantics using non-monotonic reasoning
2005-01-01
Argumentation theory is an alternative style of formalizing non-monotonic reasoning. It seems, argumentation theory is a suitable framework for practical and uncertain reasoning, where arguments support conclusions. Dung's approach is an unifying framework which has played an influential role on argumentation research and Artificial Intelligence. Even though the success of the argumentation theory, it seems that argumentation theory is so far from being efficiently implemented like the logic ...
Nonparametric estimation for hazard rate monotonously decreasing system
Institute of Scientific and Technical Information of China (English)
Han Fengyan; Li Weisong
2005-01-01
Estimation of density and hazard rate is very important to the reliability analysis of a system. In order to estimate the density and hazard rate of a hazard rate monotonously decreasing system, a new nonparametric estimator is put forward. The estimator is based on the kernel function method and optimum algorithm. Numerical experiment shows that the method is accurate enough and can be used in many cases.
Stability and monotonicity of Lotka-Volterra type operators
Mukhamedov, Farrukh
2009-01-01
In the present paper, we study Lotka-Volterra (LV) type operators defined in finite dimensional simplex. We prove that any LV type operator is a surjection of the simplex. After, we introduce a new class of LV-type operators, called $M$LV type. We prove convergence of their trajectories and study certain its properties. Moreover, we show that such kind of operators have totaly different behavior than ${\\mathbf{f}}$-monotone LV type operators.
Monotone traveling wavefronts of the KPP-Fisher delayed equation
Gomez, Adrian; Trofimchuk, Sergei
In the early 2000's, Gourley (2000), Wu et al. (2001), Ashwin et al. (2002) initiated the study of the positive wavefronts in the delayed Kolmogorov-Petrovskii-Piskunov-Fisher equation u(t,x)=Δu(t,x)+u(t,x)(1-u(t-h,x)), u⩾0, x∈R. Since then, this model has become one of the most popular objects in the studies of traveling waves for the monostable delayed reaction-diffusion equations. In this paper, we give a complete solution to the problem of existence and uniqueness of monotone waves in Eq. (*). We show that each monotone traveling wave can be found via an iteration procedure. The proposed approach is based on the use of special monotone integral operators (which are different from the usual Wu-Zou operator) and appropriate upper and lower solutions associated to them. The analysis of the asymptotic expansions of the eventual traveling fronts at infinity is another key ingredient of our approach.
Solving the power flow equations: a monotone operator approach
Energy Technology Data Exchange (ETDEWEB)
Dvijotham, Krishnamurthy [California Inst. of Technology (CalTech), Pasadena, CA (United States); Low, Steven [California Inst. of Technology (CalTech), Pasadena, CA (United States); Chertkov, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-07-21
The AC power flow equations underlie all operational aspects of power systems. They are solved routinely in operational practice using the Newton-Raphson method and its variants. These methods work well given a good initial “guess” for the solution, which is always available in normal system operations. However, with the increase in levels of intermittent generation, the assumption of a good initial guess always being available is no longer valid. In this paper, we solve this problem using the theory of monotone operators. We show that it is possible to compute (using an offline optimization) a “monotonicity domain” in the space of voltage phasors. Given this domain, there is a simple efficient algorithm that will either find a solution in the domain, or provably certify that no solutions exist in it. We validate the approach on several IEEE test cases and demonstrate that the offline optimization can be performed tractably and the computed “monotonicity domain” includes all practically relevant power flow solutions.
National Research Council Canada - National Science Library
L Colombo; E Melardi; P Ferri; G Montesano; S Samir Attaalla; F Patelli; S De Cilla; G Savaresi; L Rossetti
2017-01-01
Background To evaluate functional visual parameters using photocromic and selective blue-violet light filtering spectacle lenses in patients affected by central or peripheral scotoma due to retinal diseases...
Franzblau, S G; Hinnebusch, B J; Kelley, L M; Sinclair, N A
1984-01-01
A total of 529 well and distribution potable water samples were analyzed for total coliforms by the most-probable-number and membrane filter (MF) techniques. Standard plate count bacteria and MF noncoliform bacteria were also enumerated. Frequency of coliform detection, turbidity in most-probable-number tubes, and extensive overgrowth by noncoliforms on MF filters were directly proportional to standard plate counts. Recovery of coliforms was greatest by the MF method at low (less than 100 CFU...
K., Nirmal; A. G., Sreejith; Mathew, Joice; Sarpotdar, Mayuresh; Suresh, Ambily; Prakash, Ajin; Safonova, Margarita; Murthy, Jayant
2016-07-01
We describe the characterization and removal of noises present in the Inertial Measurement Unit (IMU) MPU- 6050, which was initially used in an attitude sensor, and later used in the development of a pointing system for small balloon-borne astronomical payloads. We found that the performance of the IMU degraded with time because of the accumulation of different errors. Using Allan variance analysis method, we identified the different components of noise present in the IMU, and verified the results by the power spectral density analysis (PSD). We tried to remove the high-frequency noise using smooth filters such as moving average filter and then Savitzky Golay (SG) filter. Even though we managed to filter some high-frequency noise, these filters performance wasn't satisfactory for our application. We found the distribution of the random noise present in IMU using probability density analysis and identified that the noise in our IMU was white Gaussian in nature. Hence, we used a Kalman filter to remove the noise and which gave us good performance real time.
Directory of Open Access Journals (Sweden)
Feng Qi
2014-10-01
Full Text Available The authors find the absolute monotonicity and complete monotonicity of some functions involving trigonometric functions and related to estimates the lower bounds of the first eigenvalue of Laplace operator on Riemannian manifolds.
Non-monotonic reasoning in conceptual modeling and ontology design: A proposal
CSIR Research Space (South Africa)
Casini, G
2013-06-01
Full Text Available and modeling of defeasible information and non-monotonic reasoning services. Here we formalize a possible way of introducing non-monotonic reasoning into ORM2 schemas, enriching the language with special set of new constraints....
Directory of Open Access Journals (Sweden)
Mona M.Jamjoom
2016-05-01
Full Text Available Noisy training data have a huge negative impact on machine learning algorithms. Noise-filtering algorithms have been proposed to eliminate such noisy instances. In this work, we empirically show that the most popular noise-filtering algorithms have a large False Positive (FP error rate. In other words, these noise filters mistakenly identify genuine instances as outliers and eliminate them. Therefore, we propose more conservative outlier identification criteria that improve the FP error rate and, thus, the performance of the noise filters. With the new filter, an instance is eliminated if and only if it is misclassified by a mutual decision of Naïve Bayesian (NB classifier and the original filtering criteria being used. The number of genuine instances that are incorrectly eliminated is reduced as a result, thereby improving the classification accuracy.
Mixed Monotonicity of Partial First-In-First-Out Traffic Flow Models
Coogan, Samuel; Arcak, Murat; Kurzhanskiy, Alexander A.
2015-01-01
In vehicle traffic networks, congestion on one outgoing link of a diverging junction often impedes flow to other outgoing links, a phenomenon known as the first-in-first-out (FIFO) property. Simplified traffic models that do not account for the FIFO property result in monotone dynamics for which powerful analysis techniques exist. FIFO models are in general not monotone, but have been shown to be mixed monotone - a generalization of monotonicity that enables similarly powerful analysis techni...
Energy Technology Data Exchange (ETDEWEB)
Page, Ralph H.; Doty, Patrick F.
2017-08-01
The various technologies presented herein relate to a tiled filter array that can be used in connection with performance of spatial sampling of optical signals. The filter array comprises filter tiles, wherein a first plurality of filter tiles are formed from a first material, the first material being configured such that only photons having wavelengths in a first wavelength band pass therethrough. A second plurality of filter tiles is formed from a second material, the second material being configured such that only photons having wavelengths in a second wavelength band pass therethrough. The first plurality of filter tiles and the second plurality of filter tiles can be interspersed to form the filter array comprising an alternating arrangement of first filter tiles and second filter tiles.
Payne, Tristan G; Southam, Andrew D; Arvanitis, Theodoros N; Viant, Mark R
2009-06-01
Direct-infusion electrospray-ionization Fourier transform ion cyclotron resonance mass spectrometry (DI ESI FT-ICR MS) is increasingly being utilized in metabolomics, including the high sensitivity selected ion monitoring (SIM)-stitching approach. Accurate signal quantification and the discrimination of real signals from noise remain major challenges for this approach, with both adversely affected by factors including ion suppression during electrospray, ion-ion interactions in the detector cell, and thermally-induced white noise. This is particularly problematic for complex mixture analysis where hundreds of metabolites are present near the noise level. Here we address relative signal quantification and noise discrimination issues in SIM-stitched DI ESI FT-ICR MS-based metabolomics. Using liver tissue, we first optimized the number of scans (n) acquired per SIM window to address the balance between quantification accuracy versus acquisition time (and thus sample throughput); a minimum of n = 5 is recommended. Secondly, we characterized and computationally-corrected an effect whereby an ion's intensity is dependent upon its location within a SIM window, exhibiting a 3-fold higher intensity at the high m/z end. This resulted in significantly improved quantification accuracy. Finally, we thoroughly characterized a three-stage filter to discriminate noise from real signals, which comprised a signal-to-noise-ratio (SNR) hard threshold, then a "replicate" filter (retaining only peaks in r-out-of-3 replicate analyses), and then a "sample" filter (retaining only peaks in >s% of biological samples). We document the benefits of three-stage filtering versus one- and two-stage filters, and show the importance of selecting filter parameters that balance the confidence that a signal is real versus the total number of peaks detected.
Nirmal, K; Mathew, Joice; Sarpotdar, Mayuresh; Suresh, Ambily; Prakash, Ajin; Safonova, Margarita; Murthy, Jayant
2016-01-01
We describe the characterization and removal of noise present in the Inertial Measurement Unit (IMU) MPU-6050. This IMU was initially used in an attitude sensor (AS) developed in-house, and subsequently implemented in a pointing and stabilization platform developed for small balloon-borne astronomical payloads. We found that the performance of the IMU degrades with time due to the accumulation of different errors. Using the Allan variance analysis method, we identified the different components of noise present in the IMU and verified the results using a power spectral density analysis (PSD). We tried to remove the high-frequency noise using smoothing filters, such as moving average filter and Savitzky-Golay filter. Although we did manage to filter some of the high-frequency noise, the performance of these filters was not satisfactory for our application. We found the distribution of the random noise present in the IMU using a probability density analysis, and identified the noise to be white Gaussian in natur...
DEFF Research Database (Denmark)
Shen, Ming; Ren, Jian; Mikkelsen, Jan Hvolgaard;
2016-01-01
structures into the ring resonator. This is different from conventional designs using cascaded bandstop/low-pass filters for stop-band response suppression, which usually leads to big circuit sizes. And hence the proposed approach can reduce the circuit size significantly. A prototype filter with a compact...... size (13.6 mm×6.75 mm) has been implemented for experimental validation. The measured results show a −3 dB frequency band from 3.4 GHz to 11.7 GHz and > 20 dB upper stop-band suppression from 12.5 GHz to 20GHz....
Monotonicity Formula and Regularity for General Free Discontinuity Problems
Bucur, Dorin; Luckhaus, Stephan
2014-02-01
We give a general monotonicity formula for local minimizers of free discontinuity problems which have a critical deviation from minimality, of order d - 1. This result allows us to prove partial regularity results (that is closure and density estimates for the jump set) for a large class of free discontinuity problems involving general energies associated to the jump set, as for example free boundary problems with Robin conditions. In particular, we give a short proof to the De Giorgi-Carriero-Leaci result for the Mumford-Shah functional.
The Non-Monotonic Effect of Financing Constraints on Investment
DEFF Research Database (Denmark)
Hirth, Stefan; Viswanatha, Marc
We analyze investment timing in a discrete-time framework with two possible investment dates, which is an extension of the model by Lyandres (2007). While Lyandres could only show non-monotonicity of investment in market frictions, we derive an investment threshold that is U-shaped in the firm's ......'s liquid funds, a result similar to the infinite-horizon model by Boyle and Guthrie (2003). However, due to the tractability of our model, we can more clearly explain the relevant trade-offs leading to the U-shape....
Contribution to the ergodic theory of piecewise monotone continuous maps
Faller, Bastien
2008-01-01
This thesis is devoted to the ergodic theory of the piecewise monotone continuous maps of the interval. The coding is a classical approach for these maps. Thanks to the coding, we get a symbolic dynamical system which is almost isomorphic to the initial dynamical system. The principle of the coding is very similar to the one of expansion of real numbers. We first define the coding in a perspective similar to the one of the expansions of real numbers; this perspective was already adopted by Ré...
Stability of generalized monotonicity with respect to their characterizations
An, P T
2002-01-01
We show that known types of generalized monotone maps are not stable with respect to their characterizations (i.e., the characterizations are not maintained during an arbitrary map of this type is disturbed by an element with sufficiently small norm) then introduce s-quasimonotone maps, which are stable with respect to their characterization. For gradient maps, s-quasimonotonicity is related to s-quasiconvexity of the underlying function. A necessary and sufficient condition for a univariate polynomial to be s-quasimonotone is given. Furthermore, some stability properties of a-quasiconvex functions are presented.
Deterministic homogenization of parabolic monotone operators with time dependent coefficients
Directory of Open Access Journals (Sweden)
Gabriel Nguetseng
2004-06-01
Full Text Available We study, beyond the classical periodic setting, the homogenization of linear and nonlinear parabolic differential equations associated with monotone operators. The usual periodicity hypothesis is here substituted by an abstract deterministic assumption characterized by a great relaxation of the time behaviour. Our main tool is the recent theory of homogenization structures by the first author, and our homogenization approach falls under the two-scale convergence method. Various concrete examples are worked out with a view to pointing out the wide scope of our approach and bringing the role of homogenization structures to light.
Energy Technology Data Exchange (ETDEWEB)
Mailloux, Shay [Clarkson University, Potsdam, NY; Zavalov, Oleksandr [Clarkson University, Potsdam, NY; Guz, Nataliia [Clarkson University, Potsdam, NY; Katz, Evgeny [Clarkson University, Potsdam, NY; Bocharova, Vera [ORNL
2014-01-01
The major challenge for application of autonomous medical sensing systems is the noise produced by non-zero physiological concentrations of the sensed target. If the level of noise is high, then a real signal indicating abnormal changes in the physiological levels of the analytes might be hindered. Inevitably, this could lead to wrong diagnostics and treatment, and would have a negative impact on human health. Here, we report the realization of a filter system implemented to improve both the fidelity of sensing and accuracy of consequent drug release. A new filtering method was tested in the sensing system for the diagnosis of liver injury. This sensing system used the enzymes alanine transaminase (ALT) and aspartate transaminase (AST) as the inputs. Furthermore, the output of the sensing system was designed to trigger drug release, and therefore, the role of the filter in drug release was also investigated. The drug release system consists of beads with an iron - cross-linked alginate core coated with different numbers of layers of poly-L-lysine. Dissolution of the beads by the output signals of the sensing system in the presence and absence of the filter was monitored by release of encapsulated in the beads rhodamine - 6G dye mimicking release of a real drug. The obtained results offer a new view on the problem of noise reduction for systems intended to be part of sense and treat medical devices.
基于粒子滤波的一种改进的资料同化方法%Improved particle filter in data assimilation
Institute of Scientific and Technical Information of China (English)
冷洪泽; 宋君强; 曹小群; 杨锦辉
2012-01-01
Owing to the fact that standard particle filter and ensemble Kalman filter can not efficiently represent the posterior probability density function（PDF）,an improved particle filter is proposed.In this algorithm,an innovation step is introduced after the prediction step,and the analyses of non-observation time and observation time are treated separately.The numerical simulations of a low- and a high-dimensional systems show that this new particle filter can follow the true state of a highly nonlinear non-Gaussian system very well.%针对在粒子数较少时传统的集合卡尔曼滤波和粒子滤波方法不能有效表征后验概率密度函数（PDF）的问题,提出了一种改进的粒子滤波方法.主要思想是在预测步之后引入更新步,并且将观测时刻与非观测时刻的同化分析进行区别处理.对典型的低维和高维混沌系统的仿真结果表明：改进粒子滤波方法是一种非常有效的估计非线性非高斯随机系统状态的方法.
Energy Technology Data Exchange (ETDEWEB)
Bootkul, D., E-mail: mo_duangkhae@hotmail.com [Department of General Science, Faculty of Science, Srinakharinwirot University, Bangkok 10110 (Thailand); Supsermpol, B.; Saenphinit, N. [Western Digital Company, Ayutthaya 13160 (Thailand); Aramwit, C. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50202 (Thailand); Intarasiri, S., E-mail: saweat@gmail.com [Science and Technology Research Institute, Chiang Mai University, Chiang Mai 50202 (Thailand)
2014-08-15
Diamond-like carbon (DLC) films have been used in many applications due to their attractive combination of properties including chemical inertness, corrosion protection, biocompatibility, high hardness, and low wear rates. However, they still have some limitations such as high internal stresses and low toughness which lead to poor adhesion of films. Synthesis of nitrogen-doped DLC (N-DLC) offers the possibility of overcoming these limitations. In this study, DLC films, namely tetrahedral amorphous carbon (ta-C) and nitrogen doped tetrahedral amorphous carbon (ta-C:N) were deposited on single crystalline Si wafer substrates using the Filtered Cathodic Vacuum Arc (FCVA) technique. Film characterizations were carried out by Raman spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), triboindenter tester and nano-scratch tester. Measurement results showed that intentionally doping with nitrogen reduced the carbon sp{sup 3} content and increased the surface roughness in comparison with that of pure ta-C films. The hardness measurement confirmed the Raman and AFM analyses that adding nitrogen in ta-C films decreased the hardness, especially with high nitrogen content. However, the nano-scratch test revealed the increasing of the critical load with nitrogen. This work, then, extended its scope to investigate the properties of double-layer ta-C films which were composed of ta-C:N interlayer of various thickness around 10–30 nm and ta-C top-layer with thickness of around 80 nm. Microstructure characterization demonstrated that a ta-C:N interlayer gradually decreased the sp{sup 3} fraction in the films and increased film roughness whenever the ta-C:N interlayer thickness increased. In this structure, the tribological property in terms of adhesion to the Si substrate was significantly improved by about 20–90%, but the mechanical property in terms of hardness was gradually degraded by about 2–10%, compared to pure ta-C film, when the ta
Computational Modeling of Blood Flow in the TrapEase Inferior Vena Cava Filter
Energy Technology Data Exchange (ETDEWEB)
Singer, M A; Henshaw, W D; Wang, S L
2008-02-04
To evaluate the flow hemodynamics of the TrapEase vena cava filter using three dimensional computational fluid dynamics, including simulated thrombi of multiple shapes, sizes, and trapping positions. The study was performed to identify potential areas of recirculation and stagnation and areas in which trapped thrombi may influence intrafilter thrombosis. Computer models of the TrapEase filter, thrombi (volumes ranging from 0.25mL to 2mL, 3 different shapes), and a 23mm diameter cava were constructed. The hemodynamics of steady-state flow at Reynolds number 600 was examined for the unoccluded and partially occluded filter. Axial velocity contours and wall shear stresses were computed. Flow in the unoccluded TrapEase filter experienced minimal disruption, except near the superior and inferior tips where low velocity flow was observed. For spherical thrombi in the superior trapping position, stagnant and recirculating flow was observed downstream of the thrombus; the volume of stagnant flow and the peak wall shear stress increased monotonically with thrombus volume. For inferiorly trapped spherical thrombi, marked disruption to the flow was observed along the cava wall ipsilateral to the thrombus and in the interior of the filter. Spherically shaped thrombus produced a lower peak wall shear stress than conically shaped thrombus and a larger peak stress than ellipsoidal thrombus. We have designed and constructed a computer model of the flow hemodynamics of the TrapEase IVC filter with varying shapes, sizes, and positions of thrombi. The computer model offers several advantages over in vitro techniques including: improved resolution, ease of evaluating different thrombus sizes and shapes, and easy adaptation for new filter designs and flow parameters. Results from the model also support a previously reported finding from photochromic experiments that suggest the inferior trapping position of the TrapEase IVC filter leads to an intra-filter region of recirculating
Murphy, Erin H; Johnson, Eric D; Kopchok, George E; Fogarty, Thomas J; Arko, Frank R
2009-09-01
Inferior vena cava filters are widely accepted for pulmonary embolic prophylaxis in high-risk patients with contraindications to anticoagulation. While long-term complications have been associated with permanent filters, retrievable filters are now available and have resulted in the rapid expansion of this technology. Nonetheless, complications are still reported with optional filters. Furthermore, device tilting and thrombus load may prevent retrieval in up to 30% of patients, thereby eliminating the benefits of this technology. The Crux vena cava filter is a novel, self-centering, low-profile filter that is designed for ease of delivery, retrievability and improved efficacy while limiting fatigue-related device complications. This device has been proven safe and user-friendly in an ovine model and has recently been implanted in human subjects.
Improving Sector Hash Carving with Rule-Based and Entropy-Based Non-Probative Block Filters
2015-03-01
Whitespace rule attempts to filter out blocks that contain over three-quarters of whitespace characters, such as spaces, tabs , and newlines. These...were particularly useful, since we could use the inode number to extract a file from the drive using icat [27]. By using this contextual information
A Neurodynamic Model to Solve Nonlinear Pseudo-Monotone Projection Equation and Its Applications.
Eshaghnezhad, Mohammad; Effati, Sohrab; Mansoori, Amin
2016-09-29
In this paper, a neurodynamic model is given to solve nonlinear pseudo-monotone projection equation. Under pseudo-monotonicity condition and Lipschitz continuous condition, the projection neurodynamic model is proved to be stable in the sense of Lyapunov, globally convergent, globally asymptotically stable, and globally exponentially stable. Also, we show that, our new neurodynamic model is effective to solve the nonconvex optimization problems. Moreover, since monotonicity is a special case of pseudo-monotonicity and also since a co-coercive mapping is Lipschitz continuous and monotone, and a strongly pseudo-monotone mapping is pseudo-monotone, the neurodynamic model can be applied to solve a broader classes of constrained optimization problems related to variational inequalities, pseudo-convex optimization problem, linear and nonlinear complementarity problems, and linear and convex quadratic programming problems. Finally, several illustrative examples are stated to demonstrate the effectiveness and efficiency of our new neurodynamic model.
Burge, Johannes
2017-01-01
Accuracy Maximization Analysis (AMA) is a recently developed Bayesian ideal observer method for task-specific dimensionality reduction. Given a training set of proximal stimuli (e.g. retinal images), a response noise model, and a cost function, AMA returns the filters (i.e. receptive fields) that extract the most useful stimulus features for estimating a user-specified latent variable from those stimuli. Here, we first contribute two technical advances that significantly reduce AMA’s compute time: we derive gradients of cost functions for which two popular estimators are appropriate, and we implement a stochastic gradient descent (AMA-SGD) routine for filter learning. Next, we show how the method can be used to simultaneously probe the impact on neural encoding of natural stimulus variability, the prior over the latent variable, noise power, and the choice of cost function. Then, we examine the geometry of AMA’s unique combination of properties that distinguish it from better-known statistical methods. Using binocular disparity estimation as a concrete test case, we develop insights that have general implications for understanding neural encoding and decoding in a broad class of fundamental sensory-perceptual tasks connected to the energy model. Specifically, we find that non-orthogonal (partially redundant) filters with scaled additive noise tend to outperform orthogonal filters with constant additive noise; non-orthogonal filters and scaled additive noise can interact to sculpt noise-induced stimulus encoding uncertainty to match task-irrelevant stimulus variability. Thus, we show that some properties of neural response thought to be biophysical nuisances can confer coding advantages to neural systems. Finally, we speculate that, if repurposed for the problem of neural systems identification, AMA may be able to overcome a fundamental limitation of standard subunit model estimation. As natural stimuli become more widely used in the study of psychophysical and
Testing monotonicity of a hazard: asymptotic distribution theory
Groeneboom, Piet
2011-01-01
Two new test statistics are introduced to test the null hypotheses that the sampling distribution has an increasing hazard rate on a specified interval [0,a]. These statistics are empirical L_1-type distances between the isotonic estimates, which use the monotonicity constraint, and either the empirical distribution function or the empirical cumulative hazard. They measure the excursions of the empirical estimates with respect to the isotonic estimates, due to local non-monotonicity. Asymptotic normality of the test statistics, if the hazard is strictly increasing on [0,a], is established under mild conditions. This is done by first approximating the global empirical distance by an distance with respect to the underlying distribution function. The resulting integral is treated as sum of increasingly many local integrals to which a CLT can be applied. The behavior of the local integrals is determined by a canonical process: the difference between the stochastic process x -> W(x)+x^2 where W is standard two-sid...
DATA PREORDERING IN GENERALIZED PAV ALGORITHM FOR MONOTONIC REGRESSION
Institute of Scientific and Technical Information of China (English)
Oleg Burdakov; Anders Grimvall; Oleg Sysoev
2006-01-01
Monotonic regression (MR) is a least distance problem with monotonicity constraints induced by a partially ordered data set of observations. In our recent publication [In Ser.Nonconvex Optimization and Its Applications, Springer-Verlag, (2006) 83, pp. 25-33],the Pool-Adjacent-Violators algorithm (PAV) was generalized from completely to partially ordered data sets (posets). The new algorithm, called GPAV, is characterized by the very low computational complexity, which is of second order in the number of observations.It treats the observations in a consecutive order, and it can follow any arbitrarily chosen topological order of the poset of observations. The GPAV algorithm produces a sufficiently accurate solution to the MR problem, but the accuracy depends on the chosen topological order. Here we prove that there exists a topological order for which the resulted GPAV solution is optimal. Furthermore, we present results of extensive numerical experiments,from which we draw conclusions about the most and the least preferable topological orders.
Improved Particle Filter Algorithm and Application Simulation%改进粒子滤波算法及其应用仿真
Institute of Scientific and Technical Information of China (English)
张军; 所玉君; 董小丰; 张玉朋
2013-01-01
In view of the low precision of particle filter algorithm and particle degradation in target tracking, a GH-RPF algorithm is put forward. Based on particle filter, Gauss-Hermite filter is applied to generate the importance density function, and meanwhile canonical transformation is adopted to re-sampling in order to improve the diversity of particles. If the algorithm is applied to nonlinear and non-Gaussian target tracking, it can be seen from the simulation result that the filtering accuracy is higher and tracking performance is better compared to the standard particle filter algorithm as well as EKPF.%针对目标跟踪中粒子滤波算法的估计精度不高、粒子退化问题，文中提出了一种 GH-RPF 算法。在粒子滤波的基础上，应用高斯-厄米特滤波来产生重要密度函数，同时对重采样采用正则变换以改善采样粒子的多样性。将该算法应用于非线性、非高斯的目标跟踪中，仿真结果表明，与标准粒子滤波及 EKPF 相比，该算法的滤波精度更高，具有更高的跟踪性能。
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
A noninterior continuation method is proposed for semidefinite complementarity problem (SDCP). This method improves the noninterior continuation methods recently developed for SDCP by Chen and Tseng. The main properties of our method are: (i)it is well defined for the monotones SDCP; (ii) it has to solve just one linear system of equations at each step; (iii) it is shown to be both globally linearly convergent and locally quadratically convergent under suitable assumptions.
1991-12-01
depicts accelerometer and gyro initial thermal transients. The 6 thermal tran- sient states are first order Markov processes in the system and Kalman...1th and filter modIla (22). A one-run Monte Caz!o ai- sis,. a 2-hour flight trajectory of Stacey’s NRS using MSOFE on a 3 MIP VAX worl ’.i,ttiE’n
Directory of Open Access Journals (Sweden)
Wen-Chang Cheng
2012-12-01
Full Text Available In this paper we propose a robust lane detection and tracking method by combining particle filters with the particle swarm optimization method. This method mainly uses the particle filters to detect and track the local optimum of the lane model in the input image and then seeks the global optimal solution of the lane model by a particle swarm optimization method. The particle filter can effectively complete lane detection and tracking in complicated or variable lane environments. However, the result obtained is usually a local optimal system status rather than the global optimal system status. Thus, the particle swarm optimization method is used to further refine the global optimal system status in all system statuses. Since the particle swarm optimization method is a global optimization algorithm based on iterative computing, it can find the global optimal lane model by simulating the food finding way of fish school or insects under the mutual cooperation of all particles. In verification testing, the test environments included highways and ordinary roads as well as straight and curved lanes, uphill and downhill lanes, lane changes, etc. Our proposed method can complete the lane detection and tracking more accurately and effectively then existing options.
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)
李太福; 姚立忠; 易军; 胡文金; 苏盈盈; 贾威
2014-01-01
The aluminum electrolysis process has multiple characteristics including multivariate, strong coupling, strong interference and time-varying parameters. Therefore, its model development is technically difficult. According to the characteristics of the process, an improved unscented Kalman filter neural network based on strong tracking filter and square root filter (STR-UKFNN) is proposed in this paper. Then, the STR-UKFNN is used to create the dynamic evolutionary model for energy consumption of aluminum reduction cell. Firstly, the state covariance matrix of the UKFNN algorithm is replaced by its square root to participate in recursive operations; Secondly, the filter gain matrice in the algorithm of UKFNN is adjusted by introducing the time-varying fading factor and the diminishing factor. A series of experiments have been conducted by using the daily samples from the 170 kA new pre-baked cell. The experimental results show that the method improves the precision of the energy model and the real-time tracking ability for the abrupt state change of the aluminum reduction cell. So the method is helpful to guide the optimization of operating parameters in the aluminum electrolysis process.%铝电解过程具有多变量、强耦合、强干扰、参数时变等特征,故其模型开发是一个技术难点。根据该过程的特点,本文提出强跟踪平方根无迹Kalman 神经网络(Strong tracking square root unscented Kalman filter neural network, STR-UKFNN),并用其建立铝电解槽工艺能耗的动态演化模型。该方法利用误差协方差矩阵的平方根代替UKFNN 算法中的协方差阵,避免误差协方差矩阵可能出现负定而导致滤波发散,并在UKFNN 算法中引入渐消因子和弱化因子,实时调整滤波增益,提高模型收敛速度和其对突变状态的跟踪能力。通过某铝厂170 kA 预焙槽的日报样本验证表明,该方法提高了能耗模型的精度和对电解槽突变状态的实时跟踪能力,有
The regularized monotonicity method: detecting irregular indefinite inclusions
DEFF Research Database (Denmark)
Garde, Henrik; Staboulis, Stratos
2017-01-01
In inclusion detection in electrical impedance tomography, the support of perturbations (inclusion) from a known background conductivity is typically reconstructed from idealized continuum data modelled by a Neumann-to-Dirichlet map. Only few reconstruction methods apply when detecting indefinite...... of approximative measurement models, including the Complete Electrode Model, hence making the method robust against modelling error and noise. In particular, we demonstrate that for a convergent family of approximative models there exists a sequence of regularization parameters such that the outer shape...... of the inclusions is asymptotically exactly characterized. Finally, a peeling-type reconstruction algorithm is presented and, for the first time in literature, numerical examples of monotonicity reconstructions for indefinite inclusions are presented....
Convex analysis and monotone operator theory in Hilbert spaces
Bauschke, Heinz H
2017-01-01
This reference text, now in its second edition, offers a modern unifying presentation of three basic areas of nonlinear analysis: convex analysis, monotone operator theory, and the fixed point theory of nonexpansive operators. Taking a unique comprehensive approach, the theory is developed from the ground up, with the rich connections and interactions between the areas as the central focus, and it is illustrated by a large number of examples. The Hilbert space setting of the material offers a wide range of applications while avoiding the technical difficulties of general Banach spaces. The authors have also drawn upon recent advances and modern tools to simplify the proofs of key results making the book more accessible to a broader range of scholars and users. Combining a strong emphasis on applications with exceptionally lucid writing and an abundance of exercises, this text is of great value to a large audience including pure and applied mathematicians as well as researchers in engineering, data science, ma...
Monotonic childhoods: representations of otherness in research writing
Directory of Open Access Journals (Sweden)
Denise Marcos Bussoletti
2011-12-01
Full Text Available This paper is part of a doctoral thesis entitled “Monotonic childhoods – a rhapsody of hope”. It follows the perspective of a critical psychosocial and cultural study, and aims at discussing the other’s representation in research writing, electing childhood as an allegorical and refl ective place. It takes into consideration, by means of analysis, the drawings and poems of children from the Terezin ghetto during the Second World War. The work is mostly based on Serge Moscovici’s Social Representation Theory, but it is also in constant dialogue with other theories and knowledge fi elds, especially Walter Benjamin’s and Mikhail Bakhtin’s contributions. At the end, the paper supports the thesis that conceives poetics as one of the translation axes of childhood cultures.
Strong convergence theorems for maximal monotone mappings in Banach spaces
Zegeye, Habtu
2008-07-01
Let E be a uniformly convex and 2-uniformly smooth real Banach space with dual E*. Let be a Lipschitz continuous monotone mapping with A-1(0)[not equal to][empty set]. For given u,x1[set membership, variant]E, let {xn} be generated by the algorithm xn+1:=[beta]nu+(1-[beta]n)(xn-[alpha]nAJxn), n[greater-or-equal, slanted]1, where J is the normalized duality mapping from E into E* and {[lambda]n} and {[theta]n} are real sequences in (0,1) satisfying certain conditions. Then it is proved that, under some mild conditions, {xn} converges strongly to x*[set membership, variant]E where Jx*[set membership, variant]A-1(0). Finally, we apply our convergence theorems to the convex minimization problems.
Convergence of the natural approximations of piecewise monotone interval maps.
Haydn, Nicolai
2004-06-01
We consider piecewise monotone interval mappings which are topologically mixing and satisfy the Markov property. It has previously been shown that the invariant densities of the natural approximations converge exponentially fast in uniform pointwise topology to the invariant density of the given map provided its derivative is piecewise Lipshitz continuous. We provide an example of a map which is Lipshitz continuous and for which the densities converge in the bounded variation norm at a logarithmic rate. This shows that in general one cannot expect exponential convergence in the bounded variation norm. Here we prove that if the derivative of the interval map is Holder continuous and its variation is well approximable (gamma-uniform variation for gamma>0), then the densities converge exponentially fast in the norm.
A COMPARISON OF DIFFERENT CONTRACTION METHODS FOR MONOTONE VARIATIONAL INEQUALITIES
Institute of Scientific and Technical Information of China (English)
Bingsheng He; Xiang Wang; Junfeng Yang
2009-01-01
It is interesting to compare the efficiency of two methods when their computational loads in each iteration are equal. In this paper, two classes of contraction methods for monotone variational inequalities are studied in a unified framework. The methods of both classes can be viewed as prediction-correction methods, which generate the same test vector in the prediction step and adopt the same step-size rule in the correction step. The only difference is that they use different search directions. The computational loads of each iteration of the different classes are equal. Our analysis explains theoretically why one class of the contraction methods usually outperforms the other class. It is demonstrated that many known methods belong to these two classes of methods. Finally, the presented numerical results demonstrate the validity of our analysis.
MINLIP for the Identification of Monotone Wiener Systems
Pelckmans, Kristiaan
2010-01-01
This paper studies the MINLIP estimator for the identification of Wiener systems consisting of a sequence of a linear FIR dynamical model, and a monotonically increasing (or decreasing) static function. Given $T$ observations, this algorithm boils down to solving a convex quadratic program with $O(T)$ variables and inequality constraints, implementing an inference technique which is based entirely on model complexity control. The resulting estimates of the linear submodel are found to be almost consistent when no noise is present in the data, under a condition of smoothness of the true nonlinearity and local Persistency of Excitation (local PE) of the data. This result is novel as it does not rely on classical tools as a 'linearization' using a Taylor decomposition, nor exploits stochastic properties of the data. It is indicated how to extend the method to cope with noisy data, and empirical evidence contrasts performance of the estimator against other recently proposed techniques.
A new approximate proximal point algorithm for maximal monotone operator
Institute of Scientific and Technical Information of China (English)
HE; Bingsheng(何炳生); LIAO; Lizhi(廖立志); YANG; Zhenhua(杨振华)
2003-01-01
The problem concerned in this paper is the set-valued equation 0 ∈ T(z) where T is a maximal monotone operator. For given xk and βk ＞ 0, some existing approximate proximal point algorithms take xk+1 = xk such that xk +ek∈ xk + βkT(xk) and||ek|| ≤ηk||xk - xk||, where {ηk} is a non-negative summable sequence. Instead of xk+1 = xk, the new iterate of the proposing method is given by xk+1 = PΩ[xk - ek], where Ω is the domain of T and PΩ(@) denotes the projection on Ω. The convergence is proved under a significantly relaxed restriction supk＞0 ηk ＜ 1.
Payoff-monotonic game dynamics and the maximum clique problem.
Pelillo, Marcello; Torsello, Andrea
2006-05-01
Evolutionary game-theoretic models and, in particular, the so-called replicator equations have recently proven to be remarkably effective at approximately solving the maximum clique and related problems. The approach is centered around a classic result from graph theory that formulates the maximum clique problem as a standard (continuous) quadratic program and exploits the dynamical properties of these models, which, under a certain symmetry assumption, possess a Lyapunov function. In this letter, we generalize previous work along these lines in several respects. We introduce a wide family of game-dynamic equations known as payoff-monotonic dynamics, of which replicator dynamics are a special instance, and show that they enjoy precisely the same dynamical properties as standard replicator equations. These properties make any member of this family a potential heuristic for solving standard quadratic programs and, in particular, the maximum clique problem. Extensive simulations, performed on random as well as DIMACS benchmark graphs, show that this class contains dynamics that are considerably faster than and at least as accurate as replicator equations. One problem associated with these models, however, relates to their inability to escape from poor local solutions. To overcome this drawback, we focus on a particular subclass of payoff-monotonic dynamics used to model the evolution of behavior via imitation processes and study the stability of their equilibria when a regularization parameter is allowed to take on negative values. A detailed analysis of these properties suggests a whole class of annealed imitation heuristics for the maximum clique problem, which are based on the idea of varying the parameter during the imitation optimization process in a principled way, so as to avoid unwanted inefficient solutions. Experiments show that the proposed annealing procedure does help to avoid poor local optima by initially driving the dynamics toward promising regions in
Indian Academy of Sciences (India)
R BALASUBRAMANIAN; R SANKARAN; S PALANI
2017-09-01
This paper deals with design and simulation of a three-phase shunt hybrid power filter consisting of a pair of 5th and 7th selective harmonic elimination passive power filters connected in series with a conventional active power filter with reduced kVA rating. The objective is to enhance the power quality in a distributionnetwork feeding variety of non-linear, time-varying and unbalanced loads. The theory and modelling of the entire power circuit in terms of synchronously rotating reference frame and leading to a non-linear control scheme is presented. This work involves introduction of individual fuzzy logic controllers for d and q axiscurrent control and for voltage regulation of the DC link capacitor. The simulation schematic covering the power and control circuits have been developed taking into account severe harmonic distortion caused by non-linear and unbalanced loads. The effectiveness of the fuzzy logic controller for the compensation of harmonics and reactive power has been verified by successive simulation runs and analysis of the results. The proposed controller is also able to compensate the distortion generated by the voltage- and current-fed non-linear loads, unbalanced and dynamically varying loads. Further, excellent regulation of the DC link voltage is accomplished, which significantly contributes to improvement of power quality.
Directory of Open Access Journals (Sweden)
Watcharaporn Wongsakoonkan
2014-06-01
Full Text Available This study aimed to investigate suitable types and ratios of materials for making clay-pots, and their performance to improve the physical and bacteriological quality of drinking water. Synthetic water was prepared and used to select suitable types and ratios for clay-pot water filters. The clay-pots were prepared by combining clay with sand, coconut-shell charcoal, and rice-husk charcoal, at various ratios. The results indicated that all types and ratios could remove 100% of coliform bacteria and Escherichia coli, and were thus suitable for treating drinking water. However, for practical use, the system should have real-world application. Therefore, filtration rate/inner surface area/time was used as a criterion to determine suitable types and ratios. Different types of clay-plot water filter yielded significantly different filtration rates (p 0.01. A ratio with a maximal filtration rate of 60:40(0.38 ± 0.28 mL/cm2/hr was found to be suitable. The quality of filtered water was acceptable in terms of turbidity, coliform bacteria level, and Escherichia coli, according to WHO drinking-water quality guidelines.
一种基于Web日志的Item-Based协同过滤算法改进%Improved Item-Based Collaborative Filtering Based on Web Log
Institute of Scientific and Technical Information of China (English)
王春才; 邢晖; 吕东方
2015-01-01
在目前众多的电子商务推荐方法中，协同过滤的研究和应用最为广泛。但由于其自身存在的一些诸如数据稀疏性与缺少个性化等问题，导致推荐的准确度与效率不高。而且U ser‐Based协同过滤算法存在用户规模过大、不易寻找最近邻的问题。因此，引入了Web日志挖掘方法，并利用Item‐Based等相关技术，以提高推荐准确度。%Nowadays the research and application of collaborative filtering is the most popular method in many of the e‐commerce recommendation techniques .But since collaborative filtering has some problems such as data sparseness and lack of individuation that decline the accuracy and efficiency of recommendation .And User‐Based collaborative filtering is difficult to find nearest neighbors when the size of users are too big .So we proposed web log mining ,item clustering and other related technologies to improve the accuracy and efficiency of recommendation .
Institute of Scientific and Technical Information of China (English)
LI Hong-gang; PAN Xian-bing
2008-01-01
We introduced a new class of fuzzy set-valued variational inclusions with (H,η)-monotone mappings. Using the resolvent operator method in Hilbert spaces, we suggested a new proximal point algorithm for finding approximate solutions, which strongly converge to the exact solution of a fuzzy set-valued variational inclusion with (H,η)-monotone. The results improved and generalized the general quasi-variational inclusions with fuzzy set-valued mappings proposed by Jin and Tian [Jin MM, Perturbed proximal point algorithm for general quasi-variational inclusions with fuzzy set-valued mappings, OR Transactions, 2005, 9(3): 31-38, (In Chinese); Tian YX, Generalized nonlinear implicit quasi-variational inclusions with fuzzy mappings, Computers & Mathematics with Applications, 2001, 42: 101-108].
Directory of Open Access Journals (Sweden)
Pongsakorn Sunthrayuth
2012-01-01
Full Text Available We introduce a new iterative algorithm for finding a common element of the set of solutions of a system of generalized mixed equilibrium problems, zero set of the sum of a maximal monotone operators and inverse-strongly monotone mappings, and the set of common fixed points of an infinite family of nonexpansive mappings with infinite real number. Furthermore, we prove under some mild conditions that the proposed iterative algorithm converges strongly to a common element of the above four sets, which is a solution of the optimization problem related to a strongly positive bounded linear operator. The results presented in the paper improve and extend the recent ones announced by many others.
Improved Kalman Filtering Algorithm in Non-Uniformity Correction%改进的卡尔曼滤波非均匀性校正算法
Institute of Scientific and Technical Information of China (English)
李晶; 朱斌; 郭立新; 龙波; 王小珂
2012-01-01
针对基于卡尔曼滤波(Kalman filtering,KF)的红外焦平面非均匀性校正算法的计算量和存储量较大,不利于实时性校正的缺点,提出一种改进的卡尔曼滤波非均匀性校正算法.该算法通过线性递归滤波器修正了观测方程,用每一帧块图像的统计均值来代替卡尔曼滤波校正算法中的观测矩阵,使增益矩阵得到简化.Matlab仿真实验结果证明:该算法的校正效果与传统的卡尔曼滤波校正算法相当,但大大减少了计算量和存储空间.%Aiming at the big computational complexity and memory requirement of infrared focal plane non-uniformity correction algorithm based on Kalman filtering, it cannot realize real-time correction shortage, an improved Kalman filtering non-uniformity correction algorithm is given. The proposed algorithm modified the observation model by applying linear recursion filter that the observation was instead of the mean value of every block image, then the matrix will be simplified. The simulation of Matlab proves that the computational complexity and memory requirements are significantly reduced, while the correction result is similar.
Robustifying Vector Median Filter
Directory of Open Access Journals (Sweden)
Valentín Gregori
2011-08-01
Full Text Available This paper describes two methods for impulse noise reduction in colour images that outperform the vector median filter from the noise reduction capability point of view. Both methods work by determining first the vector median in a given filtering window. Then, the use of complimentary information from componentwise analysis allows to build robust outputs from more reliable components. The correlation among the colour channels is taken into account in the processing and, as a result, a more robust filter able to process colour images without introducing colour artifacts is obtained. Experimental results show that the images filtered with the proposed method contain less noisy pixels than those obtained through the vector median filter. Objective measures demonstrate the goodness of the achieved improvement.
Strong Stationary Duality for M\\"obius Monotone Markov Chains: Unreliable Networks
Lorek, Pawel
2011-01-01
For Markov chains with a partially ordered finite state space we show strong stationary duality under the condition of M\\"obius monotonicity of the chain. We show relations of M\\"obius monotonicity to other definitions of monotone chains. We give examples of dual chains in this context which have transitions only upwards. We illustrate general theory by an analysis of nonsymmetric random walks on the cube with an application to networks of queues.
一种开关中值滤波器的改进%Improvement on Switching Median Filter
Institute of Scientific and Technical Information of China (English)
孔凡震; 李兆远
2009-01-01
Shuqun Zhang and Monhammad A Karim proposed an algorithm of a switching median filter which used one-dimensional Laplacian operator of four different directions to detect whether the pixel was noise. However, there are some flaws under the condition of loud noise. Through adaptively processing the determining the extreme points, corrected parameter r and threshold value T, we proposed a adaptive threshold switching median filter based on extreme points. The result showed that the method could control salt-and-pepper noise and protected image well.%Shuqun Zhang和Monhammad A Karim提出了一种开关中值滤波器算法,其机制是利用4个不同方向的一维拉普拉斯算子来检测像素点是否为噪声.通过判断极值点、修正参数r和对阈值T的自适应处理,提出了一种基于极值的自适应阈值开关中值滤波器.实验结果表明,滤波器算法对椒盐噪声能很好地抑制,能很好地保护图像细节.
Directory of Open Access Journals (Sweden)
G. Wu
2014-04-01
Full Text Available The Ensemble Transform Kalman Filter (ETKF assimilation scheme has recently seen rapid development and wide application. As a specific implementation of the Ensemble Kalman Filter (EnKF, the ETKF is computationally more efficient than the conventional EnKF. However, the current implementation of the ETKF still has some limitations when the observation operator is strongly nonlinear. One problem is that the nonlinear operator and its tangent-linear operator are iteratively calculated in the minimization of a nonlinear objective function similar to 4DVAR, which may be computationally expensive. Another problem is that it uses the tangent-linear approximation of the observation operator to estimate the multiplicative inflation factor of the forecast errors, which may not be sufficiently accurate. This study seeks a way to avoid these problems. First, we apply the second-order Taylor approximation of the nonlinear observation operator to avoid iteratively calculating the operator and its tangent-linear operator. The related computational cost is also discussed. Second, we propose a scheme to estimate the inflation factor when the observation operator is strongly nonlinear. Experimentation with the Lorenz-96 model shows that using the second-order Taylor approximation of the nonlinear observation operator leads to a reduction of the analysis error compared with the traditional linear approximation. Similarly, the proposed inflation scheme leads to a reduction of the analysis error compared with the procedure using the traditional inflation scheme.
On a correspondence between regular and non-regular operator monotone functions
DEFF Research Database (Denmark)
Gibilisco, P.; Hansen, Frank; Isola, T.
2009-01-01
We prove the existence of a bijection between the regular and the non-regular operator monotone functions satisfying a certain functional equation. As an application we give a new proof of the operator monotonicity of certain functions related to the Wigner-Yanase-Dyson skew information.......We prove the existence of a bijection between the regular and the non-regular operator monotone functions satisfying a certain functional equation. As an application we give a new proof of the operator monotonicity of certain functions related to the Wigner-Yanase-Dyson skew information....
Non-monotonic dynamics and crosstalk in signaling pathways and their implications for pharmacology
van Wijk, Roeland; Tans, Sander J.; Wolde, Pieter Rein Ten; Mashaghi, Alireza
2015-06-01
Currently, drug discovery approaches commonly assume a monotonic dose-response relationship. However, the assumption of monotonicity is increasingly being challenged. Here we show that for two simple interacting linear signaling pathways that carry two different signals with different physiological responses, a non-monotonic input-output relation can arise with simple network topologies including coherent and incoherent feed-forward loops. We show that non-monotonicity of the response functions has severe implications for pharmacological treatment. Fundamental constraints are imposed on the effectiveness and toxicity of any drug independent of its chemical nature and selectivity due to the specific network structure.
Institute of Scientific and Technical Information of China (English)
Igor Boglaev; Matthew Hardy
2008-01-01
This paper presents and analyzes a monotone domain decomposition algorithm for solving nonlinear singularly perturbed reaction-diffusion problems of parabolic type.To solve the nonlinear weighted average finite difference scheme for the partial differential equation,we construct a monotone domain decomposition algorithm based on a Schwarz alternating method and a box-domain decomposition.This algorithm needs only to solve linear discrete systems at each iterative step and converges monotonically to the exact solution of the nonlinear discrete problem. The rate of convergence of the monotone domain decomposition algorithm is estimated.Numerical experiments are presented.
A smoothing monotonic convergent optimal control algorithm for NMR pulse sequence design
Maximov, Ivan I; Salomon, Julien; Turinici, Gabriel
2010-01-01
The past decade has demonstrated increasing interests in using optimal control based methods within coherent quantum controllable systems. The versatility of such methods has been demonstrated with particular elegance within nuclear magnetic resonance (NMR) where natural separation between coherent and dissipative spin dynamics processes has enabled coherent quantum control over long periods of time to shape the experiment to almost ideal adoption to the spin system and external manipulations. This has led to new design principles as well as powerful new experimental methods within magnetic resonance imaging, liquid-state and solid-state NMR spectroscopy. For this development to continue and expand, it is crucially important to constantly improve the underlying numerical algorithms to provide numerical solutions which are optimally compatible with implementation on current instrumentation and at same time are numerically stable and offer fast monotonic convergence towards the target. Addressing such aims, we ...
DasGupta, Bhaskar; Enciso, German Andres; Sontag, Eduardo; Zhang, Yi
2007-01-01
A useful approach to the mathematical analysis of large-scale biological networks is based upon their decompositions into monotone dynamical systems. This paper deals with two computational problems associated to finding decompositions which are optimal in an appropriate sense. In graph-theoretic language, the problems can be recast in terms of maximal sign-consistent subgraphs. The theoretical results include polynomial-time approximation algorithms as well as constant-ratio inapproximability results. One of the algorithms, which has a worst-case guarantee of 87.9% from optimality, is based on the semidefinite programming relaxation approach of Goemans-Williamson [Goemans, M., Williamson, D., 1995. Improved approximation algorithms for maximum cut and satisfiability problems using semidefinite programming. J. ACM 42 (6), 1115-1145]. The algorithm was implemented and tested on a Drosophila segmentation network and an Epidermal Growth Factor Receptor pathway model, and it was found to perform close to optimally.
Energy Technology Data Exchange (ETDEWEB)
Hirota, Makoto, E-mail: hirota@dragon.ifs.tohoku.ac.jp [Institute of Fluid Science, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Morrison, Philip J. [Department of Physics and Institute for Fusion Studies, University of Texas at Austin, Austin, TX 78712 (United States)
2016-05-06
Highlights: • New stability criteria of stably stratified shear flow are discovered. • Our criteria substantially improve the Howard–Miles criterion (1961). • Our criteria also generalize Rayleigh's inflection point theorem. • The novel approach we found is also efficient as a numerical approach. - Abstract: Linear stability of inviscid, parallel, and stably stratified shear flow is studied under the assumption of smooth strictly monotonic profiles of shear flow and density, so that the local Richardson number is positive everywhere. The marginally unstable modes are systematically found by solving a one-parameter family of regular Sturm–Liouville problems, which can determine the stability boundaries more efficiently than solving the Taylor–Goldstein equation directly. By arguing for the non-existence of a marginally unstable mode, we derive new sufficient conditions for stability, which generalize the Rayleigh–Fjørtoft criterion for unstratified shear flows.
The Particle Filter Algorithm Based on Improved Resampling Techonology%基于重采样技术改进的粒子滤波算法
Institute of Scientific and Technical Information of China (English)
李小婷; 史健芳
2016-01-01
There exists some defects in Particle Filter algorithm based on the traditional resampling techonology such as large calculation ,severe particle impoverishment ,low estimation accuracy and so on .To solve these problems , this paper proposes an improved Particle Filter algorithm based on resampling techonology . First , the initial particles need to be processed before resampling to get a new set of particles .Then all the particles are divided into two types :one is medium weight particle collection , the other one is large weight and small weight particle collection .The medium weight particle collection remain unchanged without resamping .However ,the other one collection first has to be judged whether it can satisfy the condition for resampling .Finally ,a linear combination of large weight and small weight particles will be used to get new particles if it meets the resampling requisites .Results of simulation shows that the proposed improved Particle Filter algorithm is feasible .%基于传统重采样技术的粒子滤波算法存在着计算量大、粒子枯竭现象严重、估计精度较差的缺陷，针对这些问题，提出一种基于重采样技术改进的粒子滤波算法（Improved Resample Particle Filter ，IRPF ）。该算法首先在重采样时对粒子进行处理，得到新粒子集；然后对所有的粒子进行分类，得到两类粒子集，对中等权值粒子集不进行重采样；最后对大权值粒子和小权值粒子组成的粒子集先进行判断，若符合重采样条件，则对其使用线性组合方式进行重采样得到新粒子。仿真结果表明，提出的算法是可行的。
Improved Sensitive Image Filtering Method%一种改进的敏感图像过滤方法
Institute of Scientific and Technical Information of China (English)
陆蓓; 陈法叶; 姚金良
2011-01-01
Aiming at the shortage that existing sensitive image filtering method has higher error rate, this paper presents a sensitive image filtering method by combining skin color detection with human detection by Histogram of Gradient(HOG). Extracting features of human bodies by HOG feature, using a detection model trained by Support Vector Machine(SVM) to find out the human body, and then using the skin color detection algorithm to tell whether the image is sensitive. Experimental results show that this method can detect the sensitive images under complex background effectively. The accurate rate can achieve 90.2%, the recall rate can achieve 86.3%, and the error rate can achieve 3.5%.%针对现有敏感图像过滤方法误检率较高的问题,提出一种结合肤色检测和方向梯度直方图(HOG)人体检测的敏感图像过滤方法.采用HOG特征提取人体目标的特征集,运用支持向量机训练人体检测模型,检验图像中是否存在人体,并结合肤色检测算法判别该图像是否为敏感图像.实验结果表明,该方法能有效检测复杂背景条件下的敏感图像,其精确度为90.2％、查全率为86.3％、误检率为3.5％.
Directory of Open Access Journals (Sweden)
Peek Andrew S
2007-06-01
Full Text Available Abstract Background RNA interference (RNAi is a naturally occurring phenomenon that results in the suppression of a target RNA sequence utilizing a variety of possible methods and pathways. To dissect the factors that result in effective siRNA sequences a regression kernel Support Vector Machine (SVM approach was used to quantitatively model RNA interference activities. Results Eight overall feature mapping methods were compared in their abilities to build SVM regression models that predict published siRNA activities. The primary factors in predictive SVM models are position specific nucleotide compositions. The secondary factors are position independent sequence motifs (N-grams and guide strand to passenger strand sequence thermodynamics. Finally, the factors that are least contributory but are still predictive of efficacy are measures of intramolecular guide strand secondary structure and target strand secondary structure. Of these, the site of the 5' most base of the guide strand is the most informative. Conclusion The capacity of specific feature mapping methods and their ability to build predictive models of RNAi activity suggests a relative biological importance of these features. Some feature mapping methods are more informative in building predictive models and overall t-test filtering provides a method to remove some noisy features or make comparisons among datasets. Together, these features can yield predictive SVM regression models with increased predictive accuracy between predicted and observed activities both within datasets by cross validation, and between independently collected RNAi activity datasets. Feature filtering to remove features should be approached carefully in that it is possible to reduce feature set size without substantially reducing predictive models, but the features retained in the candidate models become increasingly distinct. Software to perform feature prediction and SVM training and testing on nucleic acid
Evolving Information Filtering for Personalized Information Service
Institute of Scientific and Technical Information of China (English)
田范江; 李丛蓉; 王鼎兴
2001-01-01
Information filtering (IF) systems are important for personalized information service. However, most current IF systems suffer from low quality and long training time. In this paper, a refined evolving information filtering method is presented. This method describes user's information need from multi-aspects and improves filtering quality through a process like natural selection. Experimental result shows this method can shorten training time, improve filtering quality, and reduce the relevance between filtering results and training sequence.
Satterthwaite, Theodore D; Elliott, Mark A; Gerraty, Raphael T; Ruparel, Kosha; Loughead, James; Calkins, Monica E; Eickhoff, Simon B; Hakonarson, Hakon; Gur, Ruben C; Gur, Raquel E; Wolf, Daniel H
2013-01-01
Several recent reports in large, independent samples have demonstrated the influence of motion artifact on resting-state functional connectivity MRI (rsfc-MRI). Standard rsfc-MRI preprocessing typically includes regression of confounding signals and band-pass filtering. However, substantial heterogeneity exists in how these techniques are implemented across studies, and no prior study has examined the effect of differing approaches for the control of motion-induced artifacts. To better understand how in-scanner head motion affects rsfc-MRI data, we describe the spatial, temporal, and spectral characteristics of motion artifacts in a sample of 348 adolescents. Analyses utilize a novel approach for describing head motion on a voxelwise basis. Next, we systematically evaluate the efficacy of a range of confound regression and filtering techniques for the control of motion-induced artifacts. Results reveal that the effectiveness of preprocessing procedures on the control of motion is heterogeneous, and that improved preprocessing provides a substantial benefit beyond typical procedures. These results demonstrate that the effect of motion on rsfc-MRI can be substantially attenuated through improved preprocessing procedures, but not completely removed.
Shaath, Nadim A
2010-04-01
The chemistry, photostability and mechanism of action of ultraviolet filters are reviewed. The worldwide regulatory status of the 55 approved ultraviolet filters and their optical properties are documented. The photostabilty of butyl methoxydibenzoyl methane (avobenzone) is considered and methods to stabilize it in cosmetic formulations are presented.
Max-Sum Diversification, Monotone Submodular Functions and Dynamic Updates
Borodin, Allan; Ye, Yuli
2012-01-01
Result diversification has many important applications in databases, operations research, information retrieval, and finance. In this paper, we study and extend a particular version of result diversification, known as max-sum diversification. More specifically, we consider the setting where we are given a set of elements in a metric space and a set valuation function $f$ defined on every subset. For any given subset $S$, the overall objective is a linear combination of $f(S)$ and the sum of the distances induced by $S$. The goal is to find a subset $S$ satisfying some constraints that maximizes the overall objective. This problem is first studied by Gollapudi and Sharma for modular set functions and for sets satisfying a cardinality constraint. We consider an extension of the modular case to the monotone submodular case, for which the previous algorithm no longer applies. Interestingly, we are able to match the 2-approximation using a natural, but different greedy algorithm. We then further extend the problem...
Non-monotonicity of trace distance under tensor products
Energy Technology Data Exchange (ETDEWEB)
Maziero, Jonas, E-mail: jonas.maziero@ufsm.br [Universidade Federal de Santa Maria (UFSM), RS (Brazil). Departamento de Fisica
2015-10-15
The trace distance (TD) possesses several of the good properties required for a faithful distance measure in the quantum state space. Despite its importance and ubiquitous use in quantum information science, one of its questionable features, its possible non-monotonicity under taking tensor products of its arguments (NMuTP), has been hitherto unexplored. In this article, we advance analytical and numerical investigations of this issue considering different classes of states living in a discrete and finite dimensional Hilbert space. Our results reveal that although this property of TD does not show up for pure states and for some particular classes of mixed states, it is present in a non-negligible fraction of the regarded density operators. Hence, even though the percentage of quartets of states leading to the NMuTP drawback of TD and its strength decrease as the system's dimension grows, this property of TD must be taken into account before using it as a figure of merit for distinguishing mixed quantum states. (author)
Dynamical zeta functions for piecewise monotone maps of the interval
Ruelle, David
2004-01-01
Consider a space M, a map f:M\\to M, and a function g:M \\to {\\mathbb C}. The formal power series \\zeta (z) = \\exp \\sum ^\\infty _{m=1} \\frac {z^m}{m} \\sum _{x \\in \\mathrm {Fix}\\,f^m} \\prod ^{m-1}_{k=0} g (f^kx) yields an example of a dynamical zeta function. Such functions have unexpected analytic properties and interesting relations to the theory of dynamical systems, statistical mechanics, and the spectral theory of certain operators (transfer operators). The first part of this monograph presents a general introduction to this subject. The second part is a detailed study of the zeta functions associated with piecewise monotone maps of the interval [0,1]. In particular, Ruelle gives a proof of a generalized form of the Baladi-Keller theorem relating the poles of \\zeta (z) and the eigenvalues of the transfer operator. He also proves a theorem expressing the largest eigenvalue of the transfer operator in terms of the ergodic properties of (M,f,g).
Completely Monotone Multisequences, Symmetric Probabilities and a Normal Limit Theorem
Indian Academy of Sciences (India)
J C Gupta
2000-11-01
Let G, be the set of all partial completely monotone multisequences of order and degree , i.e., multisequences (1, 2,$\\ldots$ ,k), 1, 2,$\\ldots$ , = 0, 1, 2,$\\ldots$ ,1 + 2 + \\$cdots$ + ≤ n, (0,0,$\\ldots$ ,0) = 1 and $(-1)^{_0}^{_0}$ (1, 2,$\\ldots$ ,)≥ 0 whenever 0 ≤ -(1 + 2 +$\\cdots$ +) where (1, 2,$\\ldots$ ,)=(1+1, 2,$\\ldots$ ,)+ (1,2+1,$\\ldots$ ,)+$\\cdots$ + (1, 2,$\\ldots$ ,+1)-(1,2,$\\ldots$ ,)$. Further, let $\\prod_{n,k}$ be the set of all symmetric probabilities on ${0, 1, 2,\\ldots ,k}^{n}$. We establish a one-to-one correspondence between the sets G, and $\\prod_{n, k}$ and use it to formulate and answer interesting questions about both. Assigning to G, the uniform probability measure, we show that, as → ∞ , any fixed section {(1, 2,$\\ldots$ ,), 1 ≤ $\\sum ≤ }, properly centered and normalized, is asymptotically multivariate normal. That is, $\\left\\{\\sqrt{\\left(\\binom{n+k}{k}\\right)}((1, 2,\\ldots ,)-c_0(1, 2,\\ldots ,), 1≤ _1+2+\\cdots +_k≤ m\\right\\}$ converges weakly to MVN[0,]; the centering constants 0(1, 2,$\\ldots$ ,) and the asymptotic covariances depend on the moments of the Dirichlet $(1, 1,\\ldots ,1; 1)$ distribution on the standard simplex in .
Directory of Open Access Journals (Sweden)
Aïcha Wahabi
2015-03-01
Full Text Available The objective of this work is the study of wind energy conversion in its entirety in order to optimize the power output, improve the quality of the energy supplied and thus make the operating point on high MPTT. For this, we are interested in modeling and simulation of a wind turbine associated with a speed multiplier, an asynchronous generator doubly-fed (DFIG and power converters interconnected via a DC bus. Then we have introduced a filter to improve the performance of the chain. We conducted the simulation and modeling of the indirect control of the DFIG. The technique adopted the algorithm is developed in Matlab/Simulink/SimPowerSystems. Simulation results are presented and analyzed at the end of this work.
The global convergence of the non-quasi-Newton methods with non-monotone line search
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
The non-quasi-Newton methods for unconstrained optimization was investigated. Non-monotone line search procedure is introduced, which is combined with the non-quasi-Newton family. Under the uniform convexity assumption on objective function, the global convergence of the non-quasi-Newton family was proved.Numerical experiments showed that the non-monotone line search was more effective.
How to project onto the monotone nonnegative cone using Pool Adjacent Violators type algorithms
Németh, A B
2012-01-01
The metric projection onto an order nonnegative cone from the metric projection onto the corresponding order cone is derived. Particularly, we can use Pool Adjacent Violators-type algorithms developed for projecting onto the monotone cone for projecting onto the monotone nonnegative cone too.
An analysis of the stability and monotonicity of a kind of control models
Directory of Open Access Journals (Sweden)
LU Yifa
2013-06-01
Full Text Available The stability and monotonicity of control systems with parameters are considered.By the iterative relationship of the coefficients of characteristic polynomials and the Mathematica software,some sufficient conditions for the monotonicity and stability of systems are given.
Tijs, S.H.; Moretti, S.; Brânzei, R.; Norde, H.W.
2005-01-01
A new way is presented to define for minimum cost spanning tree (mcst-) games the irreducible core, which is introduced by Bird in 1976.The Bird core correspondence turns out to have interesting monotonicity and additivity properties and each stable cost monotonic allocation rule for mcst-problems i
A novel complex-system-view-based method for system effectiveness analysis: Monotonic indexes space
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Based on the characteristics of the complex system, this paper presents a novel method, the monotonic indexes space method, for the effectiveness analysis of the complex system. First, it presents some basic concepts and assumption such as the monotonic indexes space, monotonic indexes requirement locus, etc. Second, based on the assumption that indexes are monotonic for the requirements, an algorithm is proposed and applied to numerical approximation of monotonic indexes requirement locus with hyperboxes. Third, this paper proposes two algorithms for acquiring intersection of several monotonic indexes requirement locus. Fourth, this paper proposes the monotonic-index- space based system analysis model such as the system evaluation model, the sensitivity analysis model for indexes. Based on the practical requirement, the concept of fuzzy monotonic indexes requirement locus and the corresponding analysis model are introduced. Finally, this paper applies the above-mentioned models to analyze the effectiveness of a notional anti-stealth-air-defense information system. And the outputs show that the method is promising.
Effects of temperature on monotonic and fatigue properties of carbon fibre epoxy cross ply laminates
Matsuhisa, Y.; King, J.
1993-01-01
The effects of test temperature on damage accumulation behaviour has been studied using "Torayca" T800H / #3631 in conditions of monotonic and fatigue loading. The damage accumulation behaviour was found to vary as a function of the test temperature, with the effect of temperature on the damage behaviour being different between monotonic and fatigue loading.
Effects of temperature on monotonic and fatigue properties of carbon fibre epoxy cross ply laminates
Energy Technology Data Exchange (ETDEWEB)
Matsuhisa, Y. (Composite Materials Research Labs., Toray Industries Inc., Ehime (Japan)); King, J.E. (Composite Materials Research Labs., Toray Industries Inc., Ehime (Japan) Dept. of Materials Science and Metallurgy, Univ. of Cambridge (United Kingdom))
1993-11-01
The effects of test temperature on damage accumulation behaviour has been studied using ''Torayca'' T800H/[3631] in conditions of monotonic and fatigue loading. The damage accumulation behaviour was found to vary as a function of the test temperature, with the effect of temperature on the damage behaviour being different between monotonic and fatigue loading. (orig.).
Tijs, S.H.; Moretti, S.; Brânzei, R.; Norde, H.W.
2005-01-01
A new way is presented to define for minimum cost spanning tree (mcst-) games the irreducible core, which is introduced by Bird in 1976.The Bird core correspondence turns out to have interesting monotonicity and additivity properties and each stable cost monotonic allocation rule for mcst-problems
Kovyrkina, O. A.; Ostapenko, V. V.
2016-05-01
The monotonicity of the CABARET scheme approximating a hyperbolic differential equation with a sign-changing characteristic field is analyzed. Monotonicity conditions for this scheme are obtained in domains where the characteristics have a sign-definite propagation velocity and near sonic lines, on which the propagation velocity changes its sign. These properties of the CABARET scheme are illustrated by test computations.
Tijs, S.H.; Moretti, S.; Brânzei, R.; Norde, H.W.
2005-01-01
A new way is presented to define for minimum cost spanning tree (mcst-) games the irreducible core, which is introduced by Bird in 1976.The Bird core correspondence turns out to have interesting monotonicity and additivity properties and each stable cost monotonic allocation rule for mcst-problems i
Computation of displacements for nonlinear elastic beam models using monotone iterations
Directory of Open Access Journals (Sweden)
Philip Korman
1988-01-01
Full Text Available We study displacement of a uniform elastic beam subject to various physically important boundary conditions. Using monotone methods, we discuss stability and instability of solutions. We present computations, which suggest efficiency of monotone methods for fourth order boundary value problems.
Directory of Open Access Journals (Sweden)
L. Xiao
2013-04-01
Full Text Available The growing convergence among mobile computing device and smart sensors boosts the development of ubiquitous computing and smart spaces, where localization is an essential part to realize the big vision. The general localization methods based on GPS and cellular techniques are not suitable for tracking numerous small size and limited power objects in the indoor case. In this paper, we propose and demonstrate a new localization method, this method is an easy-setup and cost-effective indoor localization system based on off-the-shelf active RFID technology. Our system is not only compatible with the future smart spaces and ubiquitous computing systems, but also suitable for large-scale indoor localization. The use of low-complexity Gaussian Filter (GF, Wheel Graph Model (WGM and Probabilistic Localization Algorithm (PLA make the proposed algorithm robust and suitable for large-scale indoor positioning from uncertainty, self-adjective to varying indoor environment. Using MATLAB simulation, we study the system performances, especially the dependence on a number of system and environment parameters, and their statistical properties. The simulation results prove that our proposed system is an accurate and cost-effective candidate for indoor localization.
Afshari, Shahab; Fekete, Balazs M.; Dingman, S. Lawrence; Devineni, Naresh; Bjerklie, David M.; Khanbilvardi, Reza M.
2017-04-01
Natural streams are characterized by variation in cross-section geometry, bed-slope, bed roughness, hydraulic slope, etc., along their channels resulting from several interacting features of the riverine system including the effects of discharge changes, geologic context, sediment load, etc. Quantitative and qualitative assessment of river flow dynamics requires sufficient knowledge of hydraulics and these geophysical variables. Average flow condition theory expressed as ;At-A-Station; hydraulic geometry (AHG) relations are site-specific power-functions, relating the mean stream channel forms (i.e. water depth, top-width, flow velocity, and flow area) to discharge, have been studied since 50s. Establishing robust AHG relations requires pre-assessment of data quality by means of uncertainty analysis. Our paper introduces a recursive data filtering procedure to find both random and systematic errors in streamflow and river-survey data that can be used to produce robust and informative AHG relations. The method is first verified on synthetic data and then by experiments over: (1) real discharge-stage ratings provided by daily streamflow records of U.S. Geological Survey/National Water Information System dataset (USGS/NWIS), and (2) field river survey measurement data from USGS/NWIS. This produces robust AHG relations at 4472 monitoring stations across the U.S.
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.
Probabilistic Analysis of Pattern Formation in Monotonic Self-Assembly.
Moore, Tyler G; Garzon, Max H; Deaton, Russell J
2015-01-01
Inspired by biological systems, self-assembly aims to construct complex structures. It functions through piece-wise, local interactions among component parts and has the potential to produce novel materials and devices at the nanoscale. Algorithmic self-assembly models the product of self-assembly as the output of some computational process, and attempts to control the process of assembly algorithmically. Though providing fundamental insights, these computational models have yet to fully account for the randomness that is inherent in experimental realizations, which tend to be based on trial and error methods. In order to develop a method of analysis that addresses experimental parameters, such as error and yield, this work focuses on the capability of assembly systems to produce a pre-determined set of target patterns, either accurately or perhaps only approximately. Self-assembly systems that assemble patterns that are similar to the targets in a significant percentage are "strong" assemblers. In addition, assemblers should predominantly produce target patterns, with a small percentage of errors or junk. These definitions approximate notions of yield and purity in chemistry and manufacturing. By combining these definitions, a criterion for efficient assembly is developed that can be used to compare the ability of different assembly systems to produce a given target set. Efficiency is a composite measure of the accuracy and purity of an assembler. Typical examples in algorithmic assembly are assessed in the context of these metrics. In addition to validating the method, they also provide some insight that might be used to guide experimentation. Finally, some general results are established that, for efficient assembly, imply that every target pattern is guaranteed to be assembled with a minimum common positive probability, regardless of its size, and that a trichotomy exists to characterize the global behavior of typical efficient, monotonic self-assembly systems
Probabilistic Analysis of Pattern Formation in Monotonic Self-Assembly.
Directory of Open Access Journals (Sweden)
Tyler G Moore
Full Text Available Inspired by biological systems, self-assembly aims to construct complex structures. It functions through piece-wise, local interactions among component parts and has the potential to produce novel materials and devices at the nanoscale. Algorithmic self-assembly models the product of self-assembly as the output of some computational process, and attempts to control the process of assembly algorithmically. Though providing fundamental insights, these computational models have yet to fully account for the randomness that is inherent in experimental realizations, which tend to be based on trial and error methods. In order to develop a method of analysis that addresses experimental parameters, such as error and yield, this work focuses on the capability of assembly systems to produce a pre-determined set of target patterns, either accurately or perhaps only approximately. Self-assembly systems that assemble patterns that are similar to the targets in a significant percentage are "strong" assemblers. In addition, assemblers should predominantly produce target patterns, with a small percentage of errors or junk. These definitions approximate notions of yield and purity in chemistry and manufacturing. By combining these definitions, a criterion for efficient assembly is developed that can be used to compare the ability of different assembly systems to produce a given target set. Efficiency is a composite measure of the accuracy and purity of an assembler. Typical examples in algorithmic assembly are assessed in the context of these metrics. In addition to validating the method, they also provide some insight that might be used to guide experimentation. Finally, some general results are established that, for efficient assembly, imply that every target pattern is guaranteed to be assembled with a minimum common positive probability, regardless of its size, and that a trichotomy exists to characterize the global behavior of typical efficient, monotonic
Fused Lasso Screening Rules via the Monotonicity of Subdifferentials.
Wang, Jie; Fan, Wei; Ye, Jieping
2015-09-01
Fused Lasso is a popular regression technique that encodes the smoothness of the data. It has been applied successfully to many applications with a smooth feature structure. However, the computational cost of the existing solvers for fused Lasso is prohibitive when the feature dimension is extremely large. In this paper, we propose novel screening rules that are able to quickly identity the adjacent features with the same coefficients. As a result, the number of variables to be estimated can be significantly reduced, leading to substantial savings in computational cost and memory usage. To the best of our knowledge, the proposed approach is the first attempt to develop screening methods for the fused Lasso problem with general data matrix. Our major contributions are: 1) we derive a new dual formulation of fused Lasso that comes with several desirable properties; 2) we show that the new dual formulation of fused Lasso is equivalent to that of the standard Lasso by two affine transformations; 3) we propose a novel framework for developing effective and efficient screening rules for fused Lasso via the monotonicity of the subdifferentials (FLAMS). Some appealing features of FLAMS are: 1) our methods are safe in the sense that the detected adjacent features are guaranteed to have the same coefficients; 2) the dataset needs to be scanned only once to run the screening, whose computational cost is negligible compared to that of solving the fused Lasso; (3) FLAMS is independent of the solvers and can be integrated with any existing solvers. We have evaluated the proposed FLAMS rules on both synthetic and real datasets. The experiments indicate that FLAMS is very effective in identifying the adjacent features with the same coefficients. The speedup gained by FLAMS can be orders of magnitude.
Local Monotonicity and Isoperimetric Inequality on Hypersurfaces in Carnot groups
Directory of Open Access Journals (Sweden)
Francesco Paolo Montefalcone
2010-12-01
Full Text Available Let G be a k-step Carnot group of homogeneous dimension Q. Later on we shall present some of the results recently obtained in [32] and, in particular, an intrinsic isoperimetric inequality for a C2-smooth compact hypersurface S with boundary @S. We stress that S and @S are endowed with the homogeneous measures n????1 H and n????2 H , respectively, which are actually equivalent to the intrinsic (Q - 1-dimensional and (Q - 2-dimensional Hausdor measures with respect to a given homogeneous metric % on G. This result generalizes a classical inequality, involving the mean curvature of the hypersurface, proven by Michael and Simon [29] and Allard [1], independently. One may also deduce some related Sobolev-type inequalities. The strategy of the proof is inspired by the classical one and will be discussed at the rst section. After reminding some preliminary notions about Carnot groups, we shall begin by proving a linear isoperimetric inequality. The second step is a local monotonicity formula. Then we may achieve the proof by a covering argument.We stress however that there are many dierences, due to our non-Euclidean setting.Some of the tools developed ad hoc are, in order, a \\blow-up" theorem, which holds true also for characteristic points, and a smooth Coarea Formula for the HS-gradient. Other tools are the horizontal integration by parts formula and the 1st variation formula for the H-perimeter n????1H already developed in [30, 31] and then generalized to hypersurfaces having non-empty characteristic set in [32]. These results can be useful in the study of minimal and constant horizontal mean curvature hypersurfaces in Carnot groups.
Rosa, Ghislaine; Majorin, Fiona; Boisson, Sophie; Barstow, Christina; Johnson, Michael; Kirby, Miles; Ngabo, Fidele; Thomas, Evan; Clasen, Thomas
2014-01-01
Diarrhoea and respiratory infections remain the biggest killers of children under 5 years in developing countries. We conducted a 5-month household randomised controlled trial among 566 households in rural Rwanda to assess uptake, compliance and impact on environmental exposures of a combined intervention delivering high-performance water filters and improved stoves for free. Compliance was measured monthly by self-report and spot-check observations. Semi-continuous 24-h PM2.5 monitoring of the cooking area was conducted in a random subsample of 121 households to assess household air pollution, while samples of drinking water from all households were collected monthly to assess the levels of thermotolerant coliforms. Adoption was generally high, with most householders reporting the filters as their primary source of drinking water and the intervention stoves as their primary cooking stove. However, some householders continued to drink untreated water and most continued to cook on traditional stoves. The intervention was associated with a 97.5% reduction in mean faecal indicator bacteria (Williams means 0.5 vs. 20.2 TTC/100 mL, p<0.001) and a median reduction of 48% of 24-h PM2.5 concentrations in the cooking area (p = 0.005). Further studies to increase compliance should be undertaken to better inform large-scale interventions. Trial registration: Clinicaltrials.gov; NCT01882777; http://clinicaltrials.gov/ct2/results?term=NCT01882777&Search=Search PMID:24614750
Rosa, Ghislaine; Majorin, Fiona; Boisson, Sophie; Barstow, Christina; Johnson, Michael; Kirby, Miles; Ngabo, Fidele; Thomas, Evan; Clasen, Thomas
2014-01-01
Diarrhoea and respiratory infections remain the biggest killers of children under 5 years in developing countries. We conducted a 5-month household randomised controlled trial among 566 households in rural Rwanda to assess uptake, compliance and impact on environmental exposures of a combined intervention delivering high-performance water filters and improved stoves for free. Compliance was measured monthly by self-report and spot-check observations. Semi-continuous 24-h PM2.5 monitoring of the cooking area was conducted in a random subsample of 121 households to assess household air pollution, while samples of drinking water from all households were collected monthly to assess the levels of thermotolerant coliforms. Adoption was generally high, with most householders reporting the filters as their primary source of drinking water and the intervention stoves as their primary cooking stove. However, some householders continued to drink untreated water and most continued to cook on traditional stoves. The intervention was associated with a 97.5% reduction in mean faecal indicator bacteria (Williams means 0.5 vs. 20.2 TTC/100 mL, p<0.001) and a median reduction of 48% of 24-h PM2.5 concentrations in the cooking area (p = 0.005). Further studies to increase compliance should be undertaken to better inform large-scale interventions. Clinicaltrials.gov; NCT01882777; http://clinicaltrials.gov/ct2/results?term=NCT01882777&Search=Search.
An improved Mean Shift algorithm used for point cloud data filtering%一种改进的Mean Shift点云数据滤波
Institute of Scientific and Technical Information of China (English)
孙正林; 邹峥嵘; 吴爱琴
2011-01-01
Point cloud data filter is the key to the quality of three-dimensional reconstruction. The paperproposed an improved Mean Shift algorithm to process point cloud data directly to avoid spending a lot oftime to establish topological relations between point clouds during filtering which makes every point movedto the maximum of the kernel density estimate function quickly, so as to achieve the purpose of reducingnoise.%点云数据滤波是三维重建质量好坏的关键,为了避免在进行滤波时花费大量计算时间建立点云间的拓扑关系,提出利用改进的Mean Shift算法直接对点云数据进行处理,使其快速移动到核密度估计函数的最大值点,从而达到降低噪声的目的.
Esteblishment and improvement of melt filter for PEK unit%聚醚酮熔体过滤装置的建立与改进研究
Institute of Scientific and Technical Information of China (English)
王树江; 陈伟; 张洪刚
2012-01-01
针对聚醚酮的合成反应会产生细小固体杂质,原料、精制及干燥过程会带入灰尘等杂质,熔体挤出造粒时聚醚酮因长时间塑化和加热会产生残渣等问题,设计、建立了聚醚酮连续过滤生产装置,采用挤出机熔融、加压,再经熔体泵加压,经过高目数过滤网对其进行过滤.对装置试运行后出现的问题进行了改进,确定了适宜的操作条件,加料速度40 kg/h,挤出机加热温度375℃；出口压力12 MPa,熔体泵出口压力22～ 45 MPa,过滤网304材质,网块直径200 mm、网直径180 mm,网孔直径5μm,换网次数1次/h.测试结果表明,过滤后φ5μm的颗粒杂质个数＜6个/cm2,纯物料收率90.5％.%PEK synthesis reaction is prone to produce fine solid impurities, such as the dust and other impurities the raw materials,refining and drying process bring into,and the residue generated by PEK after long time plasticizing and heating during melt extrusion granulation. If these impurities go into the extrusion die, the clogging of the flow path or product quality issues will occur. To obtain high purity of PEK, a continuous filtering process for PEK was established, that was,the raw materials were melt and exerted pressure by the extruder,then exerted pressure again by melt pump, finally filterd by high mesh filter. According to the filtering requirements.it makes extruder,screen changer,melt pump, filter for selection and process design. Based on the problems occurred during the installation and debugging of the equipment,such as signal distortion,system instability,and so on,the scattered temperature and pressure control systems were use to improve the computer centralized control system. The optimal operation conditions for PEK melt filtration are shown as follows; 40 kg/h of feeding speed rate, 375°C of heating temperature for extruder, 12 Mpa of the outlet pressure ,22-45 Mpa of melt pump outlet pressure, filter mesh with 0200 mm, screen with Φ180 mm, screen
An Improved Sage-Husa Filter Method to Inhibit Satellite Signal Outliers%一种抑制卫星信号野值的改进Sage-Husa滤波方法
Institute of Scientific and Technical Information of China (English)
穆阳阳; 李擎; 苏中
2014-01-01
According to the problem of satellite signal outliers and filtering inaccuracy in integrated navigation area,this paper proposes usage of Sage-Husa filtering and innovation orthogonal to eliminate the impact of outliers and suppress filter divergence. Firstly,integrated navigation system measurement signal is filtered with innovation Sage-Husa Kalman filter. Secondly,an anti-outliers function is used to judge measured signal,excluding satellite signal measurement signal outliers. Contrasted innovation Sage-Husa filter car test result with classic Kalman filter and Sage-Husa filter,the results show that improved Sage-Husa filter can eliminate satellite signal measurement outliers and improve navigation accuracy.%针对组合导航中经常出现的卫星信号野值和滤波精度不高的问题，提出了利用Sage-Husa和新息正交性来消除卫星信号野值及抑制滤波器的发散，从而提高导航的精度和稳定性。首先，用改进的新息Sage-Husa卡尔曼滤波器对组合导航系统的测量信号进行滤波处理，其次，引入抗野值判断函数对测量信号进行判断，剔除卫星信号测量过程中的野值。通过跑车试验将新息Sage-Husa滤波与经典的卡尔曼滤波和Sage-Husa滤波的效果进行对比，结果表明改进的滤波算法能够有效地去除卫星野值、提高导航精度。
Institute of Scientific and Technical Information of China (English)
履之
1995-01-01
A typical food-processing plant produces about 500,000 gallons of waste water daily. Laden with organic compounds, this water usually is evaporated or discharged into sewers.A better solution is to filter the water through
Nanasato, Yoshihiko; Konagaya, Ken-Ichi; Okuzaki, Ayako; Tsuda, Mai; Tabei, Yutaka
2013-07-01
An improved method for genetic transformation of cucumber (Cucumis sativus L. cv. Shinhokusei No. 1) was developed. Vacuum infiltration of cotyledonary explants with Agrobacterium suspension enhanced the efficiency of Agrobacterium infection in the proximal regions of explants. Co-cultivation on filter paper wicks suppressed necrosis of explants, leading to increased regeneration efficiency. Putative transgenic plants were screened by kanamycin resistance and green fluorescent protein (GFP) fluorescence, and integration of the transgene into the cucumber genome was confirmed by genomic polymerase chain reaction (PCR) and Southern blotting. These transgenic plants grew normally and T1 seeds were obtained from 7 lines. Finally, stable integration and transmission of the transgene in T1 generations were confirmed by GFP fluorescence and genomic PCR. The average transgenic efficiency for producing cucumbers with our method was 11.9 ± 3.5 %, which is among the highest values reported until date using kanamycin as a selective agent.
基于模糊支持度采样的粒子滤波算法%An Improved Particle Filtering Algorithm Based on Fuzzy Support Degree Sampling
Institute of Scientific and Technical Information of China (English)
李小偎; 胡振涛; 潘泉; 张洪才
2012-01-01
针对粒子滤波中重采样导致粒子多样性减弱造成的滤波精度下降问题,给出了一种基于模糊支持度采样的改进粒子滤波算法;该算法在重采样过程后,首先根据MCMC (Markov Chain Monte Carlo)原理抽取候选粒子,然后依据重采样粒子和候选粒子自身数据中的蕴含信息,并结合模糊理论构建支持度函数和支持度矩阵,以充分地提取数据中的有效信息,在增强粒子多样性的同时实现其对于粒子的优选；最后仿真结果表明,该算法可有效地提高对于系统状态的估计精度.%By the analysis that the degeneracy of particles diversity in the course of re-sampling causes the descent of filtering precision, an improved particle filtering algorithm based on fuzzy support degree sampling is proposed. After the re-sampling process, the new algorithm firstly extracts candidate particles based on Markov Chain Monte Carlo principle, and then, according to the information implicated from the re-sampling and candidate particles and fuzzy theory establishes support degree function and matrix to make fully use of effective information. Thereby the increasing of the diversity of particles and the optimizing selection of particles are realized. Finally, simulation results show the method can effectively improve state estimation precision.
Simulation design of improved microstrip interdigital filter%一种改进型微带交指滤波器的仿真设计
Institute of Scientific and Technical Information of China (English)
陈凯; 宋长宝; 蒋勤升; 汪海兵
2012-01-01
针对微带交指滤波器KQ法及奇偶模阻抗法设计不够精确、不够简便的问题,研究了一种基于自互电容的终端短路式微带交指滤波器的设计方法,给出了详细的设计步骤及仿真设计实例.提出了一种微带交指滤波器的改进结构,该结构通过在交指滤波器的中间耦合节上增加一段λ08的微带线,使滤波器的3dB带宽从100MB减小到40 MB,带内抖动减小了2.7 dB,阻带衰减增加了2dB左右,该仿真结果证明了改进结构的有效性.%To overcome the inexactitude and inconvenience of KQ method and parity module method, this thesis researches a designing method of terminal short-circuited microstrip interdigital filter based on self-mutual capacitance, gives detailed designing steps and example of simulation design. This paper puts forward an improved structure of microwave interdigital filter, this structure adds a microstrip line whose length is λ0/8. This structure makes the 3 dB bandwidth decrease from 100 MB to 40 MB, passband dithering decrease 2.7 dB, stopband attenuation decrease about 2 dB, this simulation result shows that this improved structure is in effect.
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).
Directory of Open Access Journals (Sweden)
Watcharaporn Cholamjiak
2009-01-01
Full Text Available We prove a weak convergence theorem of the modified Mann iteration process for a uniformly Lipschitzian and generalized asymptotically quasi-nonexpansive mapping in a uniformly convex Banach space. We also introduce two kinds of new monotone hybrid methods and obtain strong convergence theorems for an infinitely countable family of uniformly Lipschitzian and generalized asymptotically quasi-nonexpansive mappings in a Hilbert space. The results improve and extend the corresponding ones announced by Kim and Xu (2006 and Nakajo and Takahashi (2003.
Filter function synthesis by Gegenbauer generating function
Directory of Open Access Journals (Sweden)
Pavlović Vlastimir D.
2006-01-01
Full Text Available Low-pass all-pole transfer functions with non-monotonic amplitude characteristic in the pass-band and at least (n -1 flatness conditions for ω = 0 are considered in this paper. A new class of filters in explicit form with one free parameter is obtained by applying generating functions of Gegenbauer polynomials. This class of filters has good selectivity and good shape of amplitude characteristics in the pass-band. The amplitude characteristics of these transfer functions have gain in the upper part of pass-band with respect to the gain for ω = 0. This way we have greater margin of attenuation in the upper part of the pass-band. This means a greater tolerance of elements or for elements with given tolerances, greater ambient temperature changes. The appropriate choice of the free parameter enables us to generate filter functions obtained with Chebyshev polynomials of the first and second kind and Legendre polynomials.
Network time transfer accuracy improvement with Kalman filter method%提高网络授时精度的Kalman滤波方法
Institute of Scientific and Technical Information of China (English)
邢开亮; 尹义蓉; 黄永华; 高勇
2011-01-01
In communication networks, the transmission of coordinated universal time ( UTC) is always influenced by delay, hence the accuracy is reduced. In this paper, a correction method based on Kalman filter has been proposed. The delay of networks is divided into three parts, which include fixed delay, jitter delay and burst delay.Kalman filter is employed to reduce the jitter delay, while a tracking door is used for burst delay reduction. Therefore , the delay of networks wiU approach to the fixed delay and the accuracy is improved. In order to verify the accuracy improvement effect of Kalman filter, the SimEvents expansion module in MATLAB is used to build a terminalto-terminal computer network transmission model. When the algorithm works steadily, the accuracy of the estimated time delay can be improved by 100 times compared with the measured time delay. A real-time test platform was designed in LabVIEW, which embeds the MATLAB program. Real-time communication network delay was obtained and then filtered. Results indicate that the proposed correction method is effective through the verification of the actual data in both wireless and cable networks.%在通信网络中传输标准时间往往受到时延很大的影响,造成精度不高.为了提高网络授时精度,提出一种基于卡尔曼滤波器的修正方法,将网络时延分解为固有延时、抖动时延、突发时延3个部分,利用Kalman滤波器减小抖动时延,利用跟踪门消除突发时延,从而使网络时延更加逼近固有时延,有利于提高授时精度.在MATLAB中运用SimEvents扩展模块,搭建一个端到端的计算机网络传输模型,验证了卡尔曼滤波对网络时延精度提高的效果,算法在稳定后,时延的估计值与测量值相比,精度可以提高大约100倍.在此基础上,利用LabVIEW设计了一个实时测试平台,嵌入MATLAB程序,实时获取通信网络时延并进行滤波处理.通过实际有线和无线网络测量的时延数据的验
Potechin, Aaron
2011-01-01
L (Logarithmic space) versus NL (Non-deterministic logarithmic space) is one of the great open problems in computational complexity theory. In the paper "Bounds on monotone switching networks for directed connectivity", we separated monotone analogues of L and NL using a model called the switching network model. In particular, by considering inputs consisting of just a path and isolated vertices, we proved that any monotone switching network solving directed connectivity on $N$ vertices must have size at least $N^{\\Omega(\\lg(N))}$ and this bound is tight. If we could show a similar result for general switching networks solving directed connectivity, then this would prove that $L \
In situ microbial filter used for bioremediation
Carman, M. Leslie; Taylor, Robert T.
2000-01-01
An improved method for in situ microbial filter bioremediation having increasingly operational longevity of an in situ microbial filter emplaced into an aquifer. A method for generating a microbial filter of sufficient catalytic density and thickness, which has increased replenishment interval, improved bacteria attachment and detachment characteristics and the endogenous stability under in situ conditions. A system for in situ field water remediation.
一种改进的滤除探地雷达直耦波的算法%An improved filter algorithm of direct arrive wave for GPR
Institute of Scientific and Technical Information of China (English)
杨凤娟; 范运岭
2013-01-01
Ground penetrating radar is a geophysical exploration method which detects the underground structure and characteristics.Because of the advantages such as high efficiency,quick speed,undamaged,and strong antinoise features,it has been applied to every aspect in engineering domain,and it is a powerful tool of shallow layer exploration.Precision of GPR exploration has important connect with data processing,processing technique which is not fit is negative to detecting result directly.With information technique and electron technique rapid development,collecting data is more various,traditional GPR processing technique is not obviously sufficient.This thesis studied the filter techniques of direct arrive wave for GPR.Because of the features of direct arrive wave that has strong correlation,strong power,horizontal,first arrival,to this traditional filter method is KL transform,it is found that KL transform is only description to information of record trace' s whole time axis after study KL transform' s theory,not to time axis' s the information,namely while KL transform filter has improved image's horizontal resolution,there is interference in vertical resolution to reduce of vertical resolution.Combining with features of wavelet's parted time and frequency,it is better to resolve part questions.Therefore,this thesis bring forward wavelet's KL transform to filter direct arrive and horizontal wave,this algorithm is not only more improve horizontal resolution than KL transform,but also overcome disadvantage of KL transform in vertical axis that is not interference.%探地雷达具有高效、快速、无损、抗干扰能力强等优点,成为浅层勘探的有力工具.雷达探测的准确性与资料处理有重要关系,处理技术将直接影响探测结果的准确性和可信度,本文主要对探地雷达信号直耦波的滤波处理技术进行了研究.典型的规则噪声直耦波具有强相关、能量强、呈水平状、出现早等特点,传统的滤
Yuan, Guangmin; Yuan, Weizheng; Xue, Liang; Xie, Jianbing; Chang, Honglong
2015-10-30
In this paper, the performance of two Kalman filter (KF) schemes based on the direct estimated model and differencing estimated model for input rate signal was thoroughly analyzed and compared for combining measurements of a sensor array to improve the accuracy of microelectromechanical system (MEMS) gyroscopes. The principles for noise reduction were presented and KF algorithms were designed to obtain the optimal rate signal estimates. The input rate signal in the direct estimated KF model was modeled with a random walk process and treated as the estimated system state. In the differencing estimated KF model, a differencing operation was established between outputs of the gyroscope array, and then the optimal estimation of input rate signal was achieved by compensating for the estimations of bias drifts for the component gyroscopes. Finally, dynamic simulations and experiments with a six-gyroscope array were implemented to compare the dynamic performance of the two KF models. The 1σ error of the gyroscopes was reduced from 1.4558°/s to 0.1203°/s by the direct estimated KF model in a constant rate test and to 0.5974°/s by the differencing estimated KF model. The estimated rate signal filtered by both models could reflect the amplitude variation of the input signal in the swing rate test and displayed a reduction factor of about three for the 1σ noise. Results illustrate that the performance of the direct estimated KF model is much higher than that of the differencing estimated KF model, with a constant input signal or lower dynamic variation. A similarity in the two KFs' performance is observed if the input signal has a high dynamic variation.
Directory of Open Access Journals (Sweden)
Guangmin Yuan
2015-10-01
Full Text Available In this paper, the performance of two Kalman filter (KF schemes based on the direct estimated model and differencing estimated model for input rate signal was thoroughly analyzed and compared for combining measurements of a sensor array to improve the accuracy of microelectromechanical system (MEMS gyroscopes. The principles for noise reduction were presented and KF algorithms were designed to obtain the optimal rate signal estimates. The input rate signal in the direct estimated KF model was modeled with a random walk process and treated as the estimated system state. In the differencing estimated KF model, a differencing operation was established between outputs of the gyroscope array, and then the optimal estimation of input rate signal was achieved by compensating for the estimations of bias drifts for the component gyroscopes. Finally, dynamic simulations and experiments with a six-gyroscope array were implemented to compare the dynamic performance of the two KF models. The 1σ error of the gyroscopes was reduced from 1.4558°/s to 0.1203°/s by the direct estimated KF model in a constant rate test and to 0.5974°/s by the differencing estimated KF model. The estimated rate signal filtered by both models could reflect the amplitude variation of the input signal in the swing rate test and displayed a reduction factor of about three for the 1σ noise. Results illustrate that the performance of the direct estimated KF model is much higher than that of the differencing estimated KF model, with a constant input signal or lower dynamic variation. A similarity in the two KFs’ performance is observed if the input signal has a high dynamic variation.
Directory of Open Access Journals (Sweden)
Salaheddine Derouiche
2013-11-01
Full Text Available In this paper, we present the implemented denoising section in the coding strategy of cochlear implants, the technique used is the technique of wavelet bionic BWT (Bionic Wavelet Transform. We have implemented the algorithm for denoising Raise the speech signal by the hybrid method BWT in the FPGA (Field Programmable Gate Array, Xilinx (Virtex5 XC5VLX110T. In our study, we considered the following: at the beginning, we present how to demonstrate features of this technique. We present an algorithm implementation we proposed, we present simulation results and the performance of this technique in terms of improvement of the SNR (Signal to Noise Ratio. The proposed implementations are realized in VHDL (Very high speed integrated circuits Hardware Description Language. Different algorithms for speech processing, including CIS (Continuous Interleaved Sampling have been implemented the strategy in this processor and tested successfully.
Monotone Iterative Technique for Duffie-Epstein Type Backward Stochastic Differential Equations
Institute of Scientific and Technical Information of China (English)
SUN Xiao-jun; WU Yue
2005-01-01
For Duffle-Epstein type Backward Stochastic Differential Equations, the comparison theorem is proved. Based on the comparison theorem, by monotone iterative technique, the existence of the minimal and maximal solutions of the equations are proved.
Monotonicity in the Sample Size of the Length of Classical Confidence Intervals
Kagan, Abram M
2012-01-01
It is proved that the average length of standard confidence intervals for parameters of gamma and normal distributions monotonically decrease with the sample size. The proofs are based on fine properties of the classical gamma function.