Double‐layer microstrip ultra‐wideband filtering power divider with high selectivity and large isolation

In this article, a compact double‐layer microstrip ultra‐wideband (UWB) filtering power divider with high selectivity and isolation is proposed. The filtering power divider consists of a multimode resonator at the top layer coupled with a pair of branch lines at the bottom through a slotline in the middle ground. The slotline provides strong coupling between the two layers and equally distributes the power to two branch lines. The resistor loaded about a quarter‐wavelength away from the slotline achieves high isolation within UWB range. The UWB filtering properties with controllable transmission poles and zeros as well as power splitting with enhanced isolation have been analyzed. The adjustable transmission zeros of the filter unit enables the bandwidth control of the filtering power divider. Finally, a UWB filtering power divider operating at 3.1 to 10.6 GHz has been designed, fabricated, and measured. It achieves a compact size of only 26 × 28 mm², high isolation about 20 dB, and good out‐of‐band suppression of 40 dB.     

鲁棒估计器在3D网格降噪中的应用

从最小平方估计的观点揭示了最小平方估计与Laplacian光顺算法之间的关联,并进一步提出了M-估计器在网格光顺中的应用,最后延伸M-估计器至二次加权的M-估计器,在抑制噪声的同时有效地保持了表面特征.在本质上,二次加权的M-估计器就是双向滤波器.     

Geometry-driven-diffusion filtering of magnetic resonance images using model-based conductance

The paper deals with the problems of staircase artifacts and low-contrast boundary smoothing in filtering (magnetic resonance MR) brain tomograms that is based on geometry-driven diffusion (GDD). A novel method of the model-based GDD filtering of MR brain tomograms is proposed to tackle these problems. It is based on a local adaptation of the conductance that is defined for each diffusion iteration within the variable limits. The local adaptation uses a neighborhood inhomogeneity measure, pixel dissimilarity, while gradient histograms of MR brain template regions are used as the variable limits for the conductance. A methodology is developed for implementing the template image selected from an MR brain atlas to the model-based GDD filtering. The proposed method is tested on an MR brain phantom. The methodology developed is exemplified on the real MR brain tomogram with the corresponding template selected from the Brainweb. The performance of the developed algorithms is evaluated quantitatively and visually. Received: 1 September 1998 / Accepted: 20 August 2000     

A novel differential filtering SIW power divider with high selectivity

A novel differential power divider with bandpass filtering response using the substrate integrated waveguide (SIW) technology is presented. An SIW resonant cavity operated in a balanced resonant mode with odd symmetric electric field distribution is utilized to provide both balanced inputs/outputs and expected common‐mode (CM) suppression in a certain band. Meanwhile, by properly constructing the cross‐coupled topology of SIW resonant cavities, the proposed differential power divider achieves a high‐selectivity bandpass filtering response with two transmission zeros on both sides of the passband. The differential power divider is designed and prototyped on a single‐layer printed circuit board (PCB). The measured center frequency is at 10.6 GHz with 490 MHz 3‐dB bandwidth. A good CM suppression can also be achieved within the operating band. The measured in‐band differential‐mode imbalance for magnitude is ±0.3 dB, while for phase is 0°–4°. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:182–188, 2016.     

The personalized context‐aware mobile advertisement system using a novel approaching detection method over cellular networks

With the rapid development of smartphones and personal tablet computers, it brings a greatly growing rate of ubiquitous applications for location‐based services (LBS). One famous LBS is the mobile advertisement. A mobile advertisement system brings benefits and opportunities among users, service providers, and advertisers. In this paper, we propose a personalized context‐aware mobile advertisement system (PCA‐MAS) over cellular networks, which contains two new techniques called (i) approaching detection method (ADM) and (ii) context‐aware ad targeting method (CAADTM). ADM can find some point of interests that a user is approaching; CAADTM pushes advertisements that satisfy user's requirement based on the user's context, that is, user's profile, current time, current position, and so on. Our experimental results show that (i) ADM has the good hit rate to determine those point of interests that a user is approaching within the 150‐m radius of the approaching range, and (ii) CAADTM has the good hit rate of finding appropriate advertisements that a user prefers through the favorite content table filtering, the annoying content table filtering, and the advertisement clicking feedback. Copyright © 2013 John Wiley & Sons, Ltd.     

Wideband filtering power dividers using single‐ and double‐layer periodic spoof surface plasmon polaritons

In this article, four wideband power dividers (two are filtering power dividers) using single‐ and double‐layer periodic spoof surface plasmon polaritons (SSPPs) are proposed. Double‐sided parallel‐strip line is used to realize the wideband and low loss for the double‐layer SSPPs. T‐shaped SSPPs power dividers with large bandwidth, wideband isolation, and low loss using double‐layer SSPPs to single‐layer SSPPs transition are realized. Conventional coplanar waveguide is used as the output ports for the single‐layer SSPPs. Moreover, two new SSPPs power dividers with filtering performance are realized with adding via holes in the double‐layer SSPPs. The theoretical analysis, parametric study, and design procedure for these wideband power dividers are illustrated. In addition, for validity demonstration, four wideband SSPPs power dividers are fabricated in microstrip technology and characterized. Good agreements can be observed between the measured and simulated results, indicating good potential applications in the integrated plasmonic devices.     

A review of: “Visual Display Terminals and Workers' Health”, WHO Offset Publications 99, WHO,Geneva (1987), pp. vi + 206, Sw. F32, $19.20, ISBN 92 4 170099 8

Abstract

Military training aims to improve load carriage performance and reduce risk of injuries. Data describing the lumbar spine (LS) postural response to load carriage throughout training are limited. We hypothesised that training would reduce the LS postural response to load. The LS posture of 27 Marines was measured from upright MR images: with and without load (22.6 kg) at the beginning, middle, and end of School of Infantry (SOI) training. Disc degeneration was graded at L5–S1. No changes in posture and disc degeneration were found throughout training. During load carriage the LS became less lordotic and the sacrum more horizontal. Marines with disc degeneration had larger sacral postural perturbations in response to load. Our findings suggest that the postural response to load is defined more by the task needs than by the physical condition of the Marine.

Practitioner Summary: The effect of military training on lumbar spine posture is unknown. The lumbar posture of 27 Marines was measured from upright MR images, with and without load throughout infantry training. No changes in posture or IVD degeneration were found across training. Marines with degeneration at the L5–S1 level had larger sacral postural perturbations in response to load.     

Spur line integrated single‐/dual‐/triple‐notched ultra‐wideband monopole antenna

Design and realization of spur line loaded frequency‐notched planar ultra‐wideband (UWB) antenna is proposed in this article. Accommodating the spur line (lines) of quarter wavelength long on the feeding microstrip line of UWB antenna, contributes to the notch‐filtering action in the feeding section itself which in turn can provides single/double/triple notch (notches) within the UWB spectrum of the antenna. The proposed technique is very simple and radiator independent as the filtering is performed in the feed region and hence the UWB radiator can be independently designed. The spur line based filtering sections are first separately designed and verified by S‐parameter measurements of the fabricated prototypes. Single, double, and triple spur line loaded microstrip sections are separately used as the feed section of a circular monopole antenna (MPA) to invoke single‐, dual‐, and triple‐notched UWB response of the MPA. All the designed prototypes are fabricated and characterized in terms of impedance and radiation parameter measurements, yielding very close correspondence with that of results obtained from full wave simulation.     

Nonlinear filtering of magnetic resonance tomograms by geometry-driven diffusion

The paper deals with a nonuniform diffusion filtering of magnetic resonance (MR) tomograms. Alternative digital schemes for discrete implementation of the nonuniform diffusion equations are analyzed and tested. A novel locally adaptive conductance for the geometry-driven diffusion (GDD) filtering is proposed. It is based on a measure of the neighborhood unhomogeneity adopted from the optimal orientation detection of linear symmetry. The algorithm performance is evaluated on the basis of pseudoartificial 2D MR brain phantom and using the signal-to-noise ratio, as well as HC measure, developed for image discrimination characterization. Three filtering methods are applied to MR images acquired by the fast 3D FLASH sequence. The results obtained are quantitatively and visually compared and discussed. Received: 24 April 1997 / Accepted: 10 November 1997     

Using new scheduling heuristics based on resource consumption information for increasing throughput on rule‐based spam filtering systems

The large increase of spam deliveries since the first half of 2013 entailed hard to solve troubles in spam filters. In order to adequately fight spam, the throughput of spam filtering platforms should be necessarily increased. In this context, and taking into consideration the widespread utilization of rule‐based filtering frameworks in the spam filtering domain, this work proposes three novel scheduling strategies for optimizing the time needed to classify new incoming e‐mails through an intelligent management of computational resources depending on the Central Processing Unit (CPU) usage and Input/Output (I/O) delays. In order to demonstrate the suitability of our approaches, we include in our experiments a comparative study in contrast to other successful heuristics previously published in the scientific literature. Results achieved demonstrated that one of our alternative heuristics allows time savings of up to 10% in message filtering, while keeping the same classification accuracy. Copyright © 2015 John Wiley & Sons, Ltd.     

A lifting undecimated wavelet transform and its applications

In order to get a characterized wavelet with expected properties, a new wavelet is constructed by using the lifting scheme (LS). Taking the low-pass filter of cubic B-splines wavelet transform as an initial filter, and designing a lifting operator based on interpolating subdivision method, new wavelet is obtained through one lifting step. The wavelet inherits the property of low-pass filtering that the initial filter possessed, and also has ability to extract transient impulse from analyzed signal. By making an equivalent interchange manipulation to the LS framework, and removing decimators, a LS algorithm for undecimated wavelet transform (UWT) is proposed. Two engineering applications are reported in the paper, and the results show that the UWT can provide much more diagnostics information than the classical wavelet transform.     

A compact dual‐band filtering antenna for wireless local area network applications

A printed dual‐band filtering antenna with decent frequency selectivity at 2.45 and 5.2 GHz for wireless local area network (WLAN) applications is developed. The filtering antenna is compact, which comprises a tapped feed line, two dual‐band stub‐loaded open‐loop resonators, and a dual‐band bended monopole. It can be easily printed on a single layer PCB substrate with low profile and low cost. The entire structure is very simple compared with the previously reported dual‐band filtering antennas that requiring multi‐layer structures. The monopole functions as not only a radiator, but also the last resonator of a dual‐band filter. The developed antenna exhibits good frequency selectivity and out‐of‐band suppression. In addition, the two operation bands can be adjusted relatively individually. The proposed antenna is optimized and fabricated. The experimental results show it has good frequency selectivity at both 2.45 and 5.2 GHz, wide bandwidth 11.8% and 7.8%, and excellent out‐of‐band suppression.     

A hybrid trust‐enhanced collaborative filtering recommendation approach for personalized government‐to‐business e‐services

The information overload on the World Wide Web results in the underuse of some existing e‐government services within the business domain. Small‐to‐medium businesses (SMBs), in particular, are seeking “one‐to‐one'' e‐services from government in current highly competitive markets, and there is an imperative need to develop Web personalization techniques to provide business users with information and services specific to their needs, rather than an undifferentiated mass of information. This paper focuses on how e‐governments can support businesses on the problem of selecting a trustworthy business partner to perform reliable business transactions. In the business partner selection process, trust or reputation information is crucial and has significant influence on a business user's decision regarding whether or not to do business with other business entities. For this purpose, an intelligent trust‐enhanced recommendation approach to provide personalized government‐to‐business (G2B) e‐services, and in particular, business partner recommendation e‐services for SMBs is proposed. Accordingly, in this paper, we develop (1) an implicit trust filtering recommendation approach and (2) an enhanced user‐based collaborative filtering (CF) recommendation approach. To further exploit the advantages of the two proposed approaches, we develop (3) a hybrid trust‐enhanced CF recommendation approach (TeCF) that integrates both the proposed implicit trust filtering and the enhanced user‐based CF recommendation approaches. Empirical results demonstrate the effectiveness of the proposed approaches, especially the hybrid TeCF recommendation approach in terms of improving accuracy, as well as in dealing with very sparse data sets and cold‐start users. © 2011 Wiley Periodicals, Inc.     

Hyperbolic‐singular‐value‐decomposition‐based square‐root accurate continuous‐discrete extended‐unscented Kalman filters for estimating continuous‐time stochastic models with discrete measurements

This paper presents novel square‐root accurate continuous‐discrete extended‐unscented Kalman filtering (ACD‐EUKF) algorithms for treating continuous‐time stochastic systems with discrete measurements. The time updates in such methods are fulfilled as those in the extended Kalman filter whereas their measurement updates are copied from the unscented Kalman filter. All this allows accurate predictions of the state mean and covariance to be combined with accurate measurement updates. The main weakness of this technique is the need for the Cholesky decomposition of predicted covariances derived in time‐update steps. Such a factorization is highly sensitive to numerical integration and round‐off errors committed, which may result in losing the covariance's positivity and, hence, failing the Cholesky decomposition. The latter problem is usually solved in the form of square‐root filtering implementations, which propagate not the covariance matrix but its square root instead. Here, we devise square‐root ACD‐EUKF methods grounded in the singular value decomposition (SVD). The SVD rooted in orthogonal transforms is applicable to any ACD‐EUKF with nonnegative weights, whereas the remaining ones, which can enjoy negative weights as well, are treated by means of the hyperbolic SVD based on J‐orthogonal transforms. The filters constructed are presented in a concise algorithmic form, which is convenient for practical use. Their two particular versions grounded in the classical and cubature unscented Kalman filtering parameterizations are examined in severe conditions of tackling a radar tracking problem, where an aircraft executes a coordinated turn. These are also compared to their non‐square‐root predecessor and other methods within the target tracking scenario with ill‐conditioned measurements.     

A generalized robust H ∞ filtering for singular Markovian jump systems and its applications

In this paper, a generalized robust H _∞ filtering method is proposed for a class of singular Markovian jump systems, whose generality is mainly embodied that the desired filter could bear perturbances in terms of uncertainties on its parameter matrices. Firstly, an LMI condition of robust mode‐dependent filter is developed. Based on the given result, a new approach to mode‐independent H _∞ filter is presented, which establishes a direct connection between mode‐dependent and mode‐independent filters. Secondly, when the transition rate matrix is with elementwise bounded uncertainties or partially unknown, sufficient conditions of such robust mode‐dependent and mode‐independent filters are all developed within LMI frameworks. Finally, a numerical example is used to demonstrate the effectiveness of the proposed methods. Copyright © 2013 John Wiley & Sons, Ltd.     

一种DTMB系统信道估计改进算法

为减小拖尾效应和加性噪声对数字电视地面广播(DTMB)系统的信道估计精度的不利影响,针对DTMB系统帧头模式2下的信道估计,提出一种改进的最小二乘(LS)信道估计算法.该算法采用试凑法从DTMB系统信号帧中PN帧头序列内选取最佳的一段PN序列,利用所选取最佳PN序列构造用于改进的LS信道估计算法的最优频域子载波,使用改进的LS信道估计算法获取信道的脉冲响应估计初值;并根据信号的正交振幅调制(QAM)方式,选取最佳噪声门限对信道的脉冲响应估计初值进行时域滤波去噪,以获得信道脉冲响应终值.仿真结果表明,该算法可有效减小拖尾效应和加性噪声对信道估计精度的影响,提高DTMB系统在帧头模式2下信道估计的精度.     

High‐gain observer with higher order sliding mode for state and unknown disturbance estimations

In this paper, we consider the estimation problem of a class of single‐input–single‐output nonlinear Lipschitz systems with nonmatching uncertainty or disturbance, where the distribution vector may include the unknown states. A hybrid nonlinear observer structure that combines a high‐gain feedback with higher order sliding mode term is proposed. The high‐gain feedback works to constrain the estimation error to within an invariant set, and the sliding mode term will asymptotically track the uncertainty if the system satisfies strict structure assumptions. Furthermore, with the higher order sliding mode, the chattering effect will be effectively attenuated without sacrificing robustness, and the system uncertainty can be recovered without filtering effect. Copyright © 2013 John Wiley & Sons, Ltd.     

Chattering reduction of sliding mode control by low‐pass filtering the control signal

The conventional approach to reducing control signal chattering in sliding mode control is to use the boundary layer design. However, when there is high‐level measurement noise, the boundary layer design becomes ineffective in chattering reduction. This paper, therefore, proposes a new design for chattering reduction by low‐pass filtering the control signal. The new design is non‐trivial since it requires estimation of the sliding variable via a disturbance estimator. The new sliding mode control has the same performance as the boundary layer design in noise‐free environments, and outperforms the boundary layer design in noisy environments. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Multiple Axis‐Aligned Filters for Rendering of Combined Distribution Effects

Distribution effects such as diffuse global illumination, soft shadows and depth of field, are most accurately rendered using Monte Carlo ray or path tracing. However, physically accurate algorithms can take hours to converge to a noise‐free image. A recent body of work has begun to bridge this gap, showing that both individual and multiple effects can be achieved accurately and efficiently. These methods use sparse sampling, GPU raytracers, and adaptive filtering for reconstruction. They are based on a Fourier analysis, which models distribution effects as a wedge in the frequency domain. The wedge can be approximated as a single large axis‐aligned filter, which is fast but retains a large area outside the wedge, and therefore requires a higher sampling rate; or a tighter sheared filter, which is slow to compute. The state‐of‐the‐art fast sheared filtering method combines low sampling rate and efficient filtering, but has been demonstrated for individual distribution effects only, and is limited by high‐dimensional data storage and processing. We present a novel filter for efficient rendering of combined effects, involving soft shadows and depth of field, with global (diffuse indirect) illumination. We approximate the wedge spectrum with multiple axis‐aligned filters, marrying the speed of axis‐aligned filtering with an even more accurate (compact and tighter) representation than sheared filtering. We demonstrate rendering of single effects at comparable sampling and frame‐rates to fast sheared filtering. Our main practical contribution is in rendering multiple distribution effects, which have not even been demonstrated accurately with sheared filtering. For this case, we present an average speedup of 6× compared with previous axis‐aligned filtering methods.     

多维滑动和（MA）模型参数的自适应估计

本文利用AR模型LS梯格滤波的有关公式给出了实时辨识多维MA模型参数的递推算法,该算法建立在对模型噪声和观测的自协方差阵和互协方差阵的矩估计基础上,由一个N阶反馈形式的梯格滤波器构成,可关于时间和阶次双重递推,该算法计算量为O(N)的量级,并具备梯格滤波固有的良好数值及结构特性。