Suitable Filter Research Articles

Multi-pattern correlation tracking

In this paper, we propose a novel multi-pattern correlation tracker (MPCT) which deeply models the appearance of the target object for robust tracking. Specifically, multiple correlation filters are learned to capture different appearance patterns of the target object during the tracking process and each filter represents one specific appearance pattern. With the proposed reliable and matching score, a two stage selection algorithm is developed to select a suitable correlation filter to localize the target object. To effectively obtain different filters, we design an online evaluation algorithm to generate filters for different appearance patterns. By taking advantage of multiple filters to model different appearance patterns, the proposed MPCT tracker can not only capture dynamic appearance changes under complex scenes but also deal with severe occlusion and model drift problems to achieve better tracking performance. Extensive experimental results prove that the proposed tracking algorithm performs superiorly against several state-of-the-art tracking methods on challenging tracking benchmarks.

Event-triggered generalized dissipative filtering for delayed neural networks under aperiodic DoS jamming attacks

This paper is concerned with event-triggered generalized dissipative filtering for delayed neural networks under aperiodic denial-of-service (DoS) attacks. Note that DoS attacks impede the wireless communications on measurement from time to time. This paper aims at designing resilient filters against DoS attacks to estimate neuronal states in the sense of dissipative. For this goal, a switched filter is introduced to cope with DoS attacks and unavailability of state information. In order to save precious communication resources, an event-triggered communication scheme is devised to transmit only necessary information to the filter. With such setting, the filtering error system is modeled as a switched system with time-delay. By employing the piecewise Lyapunov–Krasovskii functional approach and linear matrix inequality techniques, some criteria on the existence of suitable filters are presented against aperiodic DoS attacks while suitable filtering performance can be ensured. It should be mentioned that since a generalized dissipative performance index is introduced, several kinds of resilient event-based filtering issues, such as H∞ filtering, passive filtering, mixed H∞ and passive filtering, (Q, S, R)-dissipative filtering are solved in a unified framework in the presence of aperiodic DoS attacks. Finally, a numerical example is given to illustrate the effectiveness of the proposed method.

Data mining of small sample times series on detection non-stationarity properties

In this paper, a Data Mining of real times series data using Self-correlation Coefficients is investigated. The standard KPSS method was performed on real Time Series Data, in an attempt to experimentally investigate and establish the connection between small Time Series data and hidden information relating to the properties of non-stationary Time Series. The aim of this paper is to resolve this problem using a Kernel practice algorithm which is based on the extraction of Self Correlation Coefficients (SCC) combining with a non-parametric spectral density approach. In this way, the SCC is applied as suitable filter which transforms the spectral coefficients of the FFT non-parametric procedure in a parametric one such as AR. The proposed method has yielded correct classification scores in the range of versus to AR model in the small samples.

A filtration optimized on-line SPE–HPLC–MS/MS method for determination of three macrolide antibiotics dissolved and bound to suspended solids in surface water

In this work, a simple, automated multiresidue method consisting of on-line solid phase extraction coupled to liquid chromatography tandem mass spectrometry has been developed for the determination of three macrolide antibiotic residues – erythromycin, clarithromycin and azithromycin – included in the current Watch List (Decision 2018/840) of Water Framework Directive of the European Union in surface water. Due to the possible losses of target analytes, the effect of filtration on their concentrations was evaluated in terms of the filter material and pore size. Thus, glass fiber-nylon (0.45 μm and 0.22 μm pore sizes), 0.2 μm pore size nylon and 0.2 μm pore size polyvinylidene difluoride filters were used. As the Directive (2008/105/EC) prescribes the whole water monitoring, both the filtrate and solid fraction were analyzed. To estimate the analyte losses arisen from the adsorption on the solid phase, elution of the loaded filter with different aliquots of acetonitrile was also studied. The most suitable filter was the nylon of 0.2 μm pore size one, ensuring recoveries >80% for all three target analytes. By washing the filter with 2 mL acetonitrile, about 100% recovery rate was achieved for each macrolide in ultrapure water as well as river water spiked to 200 μg L−1 for each target analyte. The proposed sample pre-treatment protocol was successfully applied for the analysis of Danube River samples by using the internal standard calibration method. In one sample taken nearby a wastewater treatment plant, a relatively high concentration of clarithromycin (68 ± 0.4 ng L−1) was found.

Decentralized Dissipative Filtering for Delayed Nonlinear Interconnected Systems Based on T–S Fuzzy Model

This paper focuses on the problem of dissipative filtering for nonlinear interconnected systems with interval time-varying delays. The considered nonlinear interconnected system is modeled by Takagi–Sugeno fuzzy rules. By constructing the delay-dependent Lyapunov–Krasovskii functional and using new integral inequality, the delay-dependent condition is established to ensure that the derived closed-loop system is asymptotically stable with strict $(Q, S,R)-\alpha -$ dissipativity. In addition, a suitable filter is designed by solving a set of linear matrix inequalities. The presented method can provide better performance than the existing ones for the case of $\mathcal {H}_\infty$ filtering. A simulation example is given to demonstrate the validity of the developed filter design technique.

Reliability analysis of free space optical communication link considering the effects of laser diode chirping

In this article, wavelength chirping of a semiconductor laser due to changes in current and temperature has been measured. Based on the range of variation, a suitable combined filter consisting of a short-pass filter and long-pass filter has been selected. The link budgeting was simulated using the specifications of the transceiver designed with Zemax software, and power and wavelength chirping experimental data. The effects of wavelength chirping and atmospheric visibility conditions on the free space optical communication link’s parameters are analyzed.

Phosphate removal by iron oxide-coated diatomite: Laboratory test of a new method for cleaning drainage water

Transport of phosphate (P) in drainage water from P rich agricultural fields to freshwaters via drains may cause open water eutrophication. One way to reduce this transport is by installation of P sorbing filters at drain outlets. As drainage water flows and P concentrations can be highly fluctuating, suitable filters must have good hydraulic conductivity and high P sorbing efficiency, i.e. rapid sorption with high affinity and capacity. To fulfill these requirements, we tested a new concept for filter material design comprising porous and stable calcined diatomaceous earth particles (CDE, 2–4 mm) coated with thin layers of high affinity P sorbing amorphous iron oxide. According to NMR and MICP analyses the material had a bimodal pore size distribution with average diameters of around 1 μm and 100 μm. The coating formed a thin film on the CDE internal and external surfaces and markedly increased the P sorption efficiency. Thus, P in 0.1 and 0.5 mg P/L solutions was almost quantitatively sorbed within 1½ min at a solution:solid ratio of 100. SEM-EDX demonstrated that P quickly penetrated into the porous structure of the CDE granules and that all Fe in the coating was active in P bonding. This conceptual investigation demonstrates that porous CDE is a useful host into which Fe oxides can be precipitated resulting in an effective P sorbing material.

Shipborne gravimetry in the Baltic Sea: data processing strategies, crucial findings and preliminary geoid determination tests

Shipborne gravimetry is an essential method to measure the Earth’s gravity field in the coastal and offshore areas. It has the special advantages of high-accuracy and high-resolution measurements in coastal areas compared to other techniques (e.g., satellite gravimetry, airborne gravimetry, and altimetry) used to obtain information about the gravity field. In this paper, we present the data processing strategies of shipborne gravimetry in GFZ. One key point is that the most suitable filter parameters to eliminate disturbing accelerations are determined by studying the GNSS-derived kinematic vertical accelerations and the measurement differences at crossover points. Apart from that, two crucial issues impacting on shipborne gravimetry are the seiches in some harbors and the squat effect in the shallow water. We identified that inclusion of GNSS-derived kinematic vertical accelerations can help to improve the shipborne gravimetry results at these special cases in the Baltic Sea. In the absence of the GNSS-derived vertical accelerations, the cutoff wavelength of the low-pass filter should be large enough to filter out these disturbing acceleration signals which causes a coarser spatial resolution of the gravity measurements. Therefore, the GNSS-derived kinematic vertical accelerations are very useful for optimum shipborne gravimetry. Finally, our shipborne gravimetry measurements are successfully used to verify the previous gravimetry data and improve the current geoid models in the Baltic Sea.

Theoretical study on influence of photon reabsorption on photocarrier radiometric characteristics of silicon wafers

In microelectronic and photovoltaic industry, semiconductors are the base materials in which impurities or defects have a serious influence on the properties of semiconductor-based devices. The determination of the electronic transport properties, i.e., the carrier bulk lifetime (<inline-formula><tex-math id="M41">\begin{document}$\tau $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20181889_M41.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20181889_M41.png"/></alternatives></inline-formula>), diffusion coefficient (<i>D</i>) and front surface recombination velocity (<i>S</i><sub>1</sub>), is important in the evaluation of semiconductor materials. In this paper, the influence of reabsorption of spontaneously emitted photons within silicon wafers on conventional frequency domain photocarrier radiometric (PCR) is theoretically analyzed. The model with photon reabsorption, proposed by our previous paper, in which both band-to-band absorption and free carrier absorption are taken into account, is used. It is shown that the influence strongly depends on not only the doping level, but also the excess carrier density and its distribution, which are sensitive to the electronic transport properties. The influences of photon reabsorption on PCR amplitude and phase increase with doping level and carrier lifetime increasing. While, as the diffusion coefficient and the front surface recombination velocity increase, the influence of photon reabsorption on PCR amplitude decreases but on PCR phase increases. If photon reabsorption is ignored in the determination of the electronic transport parameters for high-doping silicon wafers via multi-parameter fitting, there are large errors for the fitted results. For a sample with <inline-formula><tex-math id="M42">\begin{document}$\tau $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20181889_M42.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="4-20181889_M42.png"/></alternatives></inline-formula> = 50 μs, <i>D</i> = 20 cm<sup>2</sup>/s, and <i>S</i><sub>1</sub> = 10 m/s, if the effect of photon reabsorption is ignored, the fitting results with conventional PCR model are 55.66 μs, 19.98 cm<sup>2</sup>/s, and 11.94 m/s, and the corresponding deviations from the true value are 11.33%, 0.10%, and 19.40%, respectively. In addition, simulation results show the effect of photon reabsorption can be greatly reduced with a suitable filter in front of the detector, while still enabling the majority of the emitted signal to be captured. For example, with a 1100 nm long-pass filter, the fitted results for the same sample above are 51.43 μs, 20.19 cm<sup>2</sup>/s, and 9.88 m/s with the relative errors of 2.86%, 0.95%, and 1.23%, respectively. It should be pointed out that an infinitely steep cut-on edge of the long-pass filter is assumed in our simulations, while in fact the influences of the filter on PCR signal and the fitted results should be further considered.

Switched <img width="58" height="55" src="http://article.sciencepublishinggroup.com/journal/248/2481135/image001.png" /> Detection Filter Design for Nonlinear Systems

This paper presents the application of the concept of detection filters to the detection of faults in nonlinear systems. The nonlinear dynamics in specific meaningful points of the operation is approximated by means of a matched array of linear systems. Then, linear filters are designed for each particular subsystem and a switching scheme is applied to carefully choose the most suitable filter regarding the operational characteristics of the plant in real time. Stability of the switching process is guaranteed by keeping the switching time between two consecutive switching large enough to ensure a proper falloff of filter transients. Therefore, apart from the solution of the standard linear-quadratic optimization problem represented by the detection filter design problem one has to derive sufficient conditions for the observation error dynamics to be globally asymptotically stable during switching. The goal is to find a common minimum of the switching time to each specific level calculated separately for every single filter that can be used as a restriction for the switching signal. The idea is demonstrated with the application to the detection of faults in the air path of a diesel engine. The results can be considered as the extension of the standard linear fault detection filtering problem to nonlinear systems.

IEEE Access Special Section Editorial: Special Section on New Developments on Reliable Control and Filtering of Complex Nonlinear Systems

During the past three decades, the problems of reliable control and filtering have attracted considerable attention due to the growing demands for system safety, reliability, maintainability, and survivability. The main aim of reliable control and filtering is to design a suitable controller and filter with guaranteed stability and performance, respectively; not only when all the system components are in operation, but also when some component failures occur. To guarantee a higher reliability level and better control performance, reliable control systems depending on various control strategies have tried to achieve these critical requirements, i.e., the pole region assignment method, coprime factorization method, the algebraic Riccati equation (ARE)-based method, the Hamilton-Jacobi inequality (HJI)-based method, and linear matrix inequality (LMI)-based method. Although many researchers have investigated the reliable control/filtering problems for linear systems with different scenarios for many years, the topic of reliable control/filtering in complex nonlinear systems is still in the early stages of development and many critical issues remain to be further investigated.

Filtered PIDA Controller for the Double Integrator Plus Dead Time

The paper proposes novel tuning of the proportional-integral-derivative-accelerative (PIDA) controller with nth order series binomial filters for the double integrator-plus-dead-time (DIPDT) plant models. In the considered context, design of a suitable filter is not only an implementation problem. It is also critical in terms of the resulting performance, robustness and noise attenuation. The proposed integrated tuning procedure (ITP) for both the ideal PIDA controller + the implementation (noise attenuation) filter is analytical, based on the multiple real dominant pole method and application of the concept of an equivalent filter delay. It is shown to enable to scale the resulting performance in an unprecedented extent. Thereby, by using the two-parameter plant approximation, it still remains sufficiently simple for users.

Slip signal analysis on a Baxter robot

Abstract The Baxter robot by ReThink Robotics is a dual arm collaborative platform, which can perform multiple tasks and is designed for use in an unstructured environment. Such robotic manipulators working in tandem have certain advantages over single arms when manipulating heavy or large, awkwardly shaped objects. With the attachment of two custom 3D-printed end-effectors, the robot gains the ability to push and hold objects of this kind. This paper deals with the preliminary steps in creating a reliable controller feedback signal using the robot’s on-board torque and positioning sensors. Determining the best joint signal and designing a suitable filter are two challenges that are addressed. The paper concludes that the torque values from the centre wrist joint undergo the largest increase in value caused by vibrations during slip. A filtering array technique is also proposed, successfully removing unwanted noise from the torque signal, allowing slip events to be effectively isolated.

High-speed stereo-digital image correlation using a single color high-speed camera.

A simple and practical high-speed stereo-digital image correlation (stereo-DIC) technique using a single off-the-shelf high-speed color CMOS camera is described in this work. By using the high-speed color CMOS camera and suitable optical filters, the recorded color images can be directly separated into red and blue channel sub-images with negligible color cross-talk between sub-channel images, which offers evident efficiency and accuracy advantages over the existing technique we proposed recently [Opt. Lasers Eng.95, 17 (2017)OLENDN0143-816610.1016/j.optlaseng.2017.03.009]. These separated sub-channel images can then be processed by regular stereo-DIC to retrieve the desired kinematic fields on the test object surface. The accuracy and precision of the established high-speed stereo-DIC system were characterized by measuring the displacements of a stationary object, and the results show good agreement with theoretical predications. To show the broad utility and practicality of the proposed method, three typical experiments, involving (i) transient displacement and velocity measurement of a rotating fan; (ii) full-field vibration measurement of a rectangular aluminum panel; and (iii) transient 3D surface shape, displacement, and strain fields measurement of a balloon during the whole explosion procedure, were carried out. The results show that, by using a proper high-speed color camera, high-speed 3D shape, displacement and deformation measurements can be realized in a cost-effective and easy-to-implement manner. The proposed technique demonstrates great potential in impact engineering, explosion, and vibration tests.

PREPROCESSING OF HOPKINSON BAR EXPERIMENT DATA: FILTER ANALYSIS

This work presents a data preprocessing procedure for signal acquired during high strain-rate loading using a custom Split Hopkinson Pressure Bar (SHPB). Before the evaluation of the experimental data, preprocessing of the measured signals including application of suitable digital or analog filter needs to be performed. Our department mainly focuses on measurements performed on advanced materials (e.g. materials with predefined structures or hybrid foams). For such measurements, it is essential to perform data preprocessing and apply suitable filter, to be able to appropriately determine deformation pulses on the measuring bars. This paper focuses foremost on spectral analysis of the measured signals, and design of optimal method of data filtering. Data from several different SHPB experiments were processed and results of different filtering methods are shown in this paper. Parameters of the best performing filter were optimized and shown to be universal for wide range of SHPB measurements.

Three-component polarization migration of channel waves for prediction ahead of coal roadway

When excavating roadways in coal mining, it is critical to predict any geological anomalies that lie ahead of the excavation in advance. Channel waves can be used for this purpose; however, the mirror imaging artefacts in the diffraction migration of channel waves must be overcome. When mixed with a Rayleigh channel wave, the polarization migration of a two-component Love channel wave is no longer possible. In this paper, the polarization situations in three-dimensional channel waves are comprehensively summarized and a new three-component channel wave polarization migration technique is proposed to remedy the deficiencies in current migration methods. The proposed technique has directional selectivity and filters out other interfering waves during the migration process, eliminates the artificial mirror phenomenon, and provides a higher imaging accuracy than other methods. However, the polarization of three-component channel waves is very complex. For example, the fundamental mode of a Rayleigh channel wave in the center of a coal seam is vertical-linearly polarized instead of elliptically polarized. In addition, the Love and Rayleigh channel waves mix easily as the group velocities of their fundamental modes are similar, and separating these necessitates the use of a special polarization filter. When two types of channel waves mix, a suitable polarization filter can be applied to suppress one or the other; however, this can produce two migration images of Love and Rayleigh channel waves. The most economical and practical means to overcome this is to record the two horizontal components at the center of the coal seam using a Love channel wave polarization migration that is independent of the Rayleigh channel wave. The proposed method was validated by way of a numerical simulation, and the results confirmed its superiority over conventional methods.

Strategies for suppressing elastically scattered laser light in ungated laser-induced breakdown spectroscopy

When an ungated detector is used for recording the signal in laser-induced breakdown spectroscopy (LIBS), elastically scattered laser light can represent a severe interference significantly limiting the dynamic range. Hence, a suitable filter must be selected from a variety of choices. In this Note, we compare different filter types and demonstrate that the filter needs to be chosen taking the experimental setup and the measurement object into account. For this purpose, dichroic and colored glass long pass filters, a dielectric Notch filter and three polarization filtering approaches are considered. Regarding the latter, a novel approach employing a half-wave plate in the laser beam is introduced and tested. Reckoning experimental data and the physical filter mechanisms allows providing guidelines for making an informed choice.

Power Quality Improvement in Stand-Alone SEIG-Based Distributed Generation System Using Lorentzian Norm Adaptive Filter

In this paper, Lorentzian norm based adaptive filter (LAF) is implemented to control voltage source converter (VSC) for improvement in power quality of three phase four wire wind based distributed generation system. This control algorithm operates VSC to control the terminal voltage and frequency in allowable range. In addition to above, neutral current compensation, load balancing, reactive power, and harmonic compensation are also carried out. Therefore, in the system, the generator always supplies the active fundamental component of load current. The LAF is derived from a sliding window type objective function with Lorentzian norm of past errors to overcome bad effect of impulsive environment on system. Hence, it is most suitable filter in wind-based distributed generation system application in order to neutralize the effect of wind impulses on the voltage and frequency of the generator. The entire system comprises induction generator, VSC, and star-delta transformer and nonlinear load is developed in MATLAB Simulink followed by a prototype in the laboratory. The control performance of the said filter is evaluated and validated by simulation and experimental analysis. After performance observation, results are found satisfactory.

Preparation of Nickel Nanoparticles by Direct Current Arc Discharge Method and Their Catalytic Application in Hybrid Na-Air Battery

Nickel nanoparticles were prepared by the arc discharge method. Argon and argon/hydrogen mixtures were used as plasma gas; the evaporation of anode material chiefly resulted in the formation of different arc-anode attachments at different hydrogen concentrations. The concentration of hydrogen was fixed at 0, 30, and 50 vol% in argon arc, corresponding to diffuse, multiple, and constricted arc-anode attachments, respectively, which were observed by using a high-speed camera. The images of the cathode and anode jets were observed with a suitable band-pass filter. The relationship between the area change of the cathode/anode jet and the synchronous voltage/current waveform was studied. By investigating diverse arc-anode attachments, the effect of hydrogen concentration on the features of nickel nanoparticles were investigated, finding that 50 vol% H2 concentration has high productivity, fine crystallinity, and appropriate size distribution. The synthesized nickel nanoparticles were then used as catalysts in a hybrid sodium–air battery. Compared with commercial a silver nanoparticle catalyst and carbon black, nickel nanoparticles have better electrocatalytic performance. The promising electrocatalytic activity of nickel nanoparticles can be ascribed to their good crystallinity, effective activation sites, and Ni/NiO composite structures. Nickel nanoparticles prepared by the direct current (DC) arc discharge method have the potential to be applied as catalysts on a large scale.

Event-Based Reliable Dissipative Filtering for T–S Fuzzy Systems With Asynchronous Constraints

In this paper, event-triggered reliable dissipative filtering is investigated for a class of Takagi–Sugeno (T–S) fuzzy systems. First, a reliable event-triggered communication scheme is introduced to release sampled measurement outputs only if the variation of the sampled vector exceeds a prescribed threshold condition. Second, an asynchronous premise reconstruct method for T–S fuzzy systems is presented, which relaxes the assumption of the prior work that the premises of the plant and the filter are synchronous. Third, the resulting filtering error system is modeled under consideration of event-triggered communication, sensor failure, and asynchronous premise in a unified framework. By adopting the Lyapunov functional method and integral inequality approach, a delay-dependent criterion is developed to guarantee asymptotic stability for the filtering error systems and achieve strict $(Q, S,R)-\alpha$ dissipativity. Consequently, suitable filters and the event parameters can be derived by solving a set of linear matrix inequalities. Finally, an example is given to show the effectiveness of the proposed method.