A novel real-time adaptive suboptimal recursive state estimation scheme for nonlinear discrete dynamic systems with non-Gaussian noise

A real-time state filtering and prediction scheme which is adaptive, recursive, and suboptimal is proposed for discrete time nonlinear dynamic systems with either Gaussian or non-Gaussian noise. The proposed scheme (PR) estimates states adaptively whenever both the observation is available and there exists a non-zero and finite number of real state roots of the observation model, otherwise the PR estimates states non-adaptively. The PR state transition and observation functions are as general as the state transition and observation functions for particle filters. The PR is based upon discrete noise approximation, state quantization, and a suboptimal implementation of multiple hypothesis testing. The PR first detects state estimate divergence points along the time axis, and then state estimate divergences are prevented by introducing new admissible state quantization levels; whereas the extended Kalman filter (EKF), sampling importance resampling (SIR) particle filter (bootstrap filter), and auxiliary sampling importance resampling (ASIR) particle filter produce diverging state estimates from actual state values for many dynamic models. The PR uses state transition functions in order to calculate transition probabilities from gates to gates. If these transition probabilities are somehow available, then state transition functions are not needed for state estimation with the PR; whereas state transition functions are necessary for state estimation with both particle filters and the EKF. The PR is very suitable for state estimation with either constraints imposed on state estimates or missing observations. The PR is more general than grid-based estimation approaches. Monte Carlo simulations have shown the effectiveness of the PR, that is, the PR performance is better than the performances of the EKF, SIR, and ASIR particle filters for many nonlinear models with white Gaussian noise, four examples of which are presented in the paper.     

Improved formulas for narrow and wide aperture dimensions of optimum gain pyramidal horn

Three formulas for the narrow and wide aperture dimensions of the pyramidal horn are improved, and the improved formulas give lower average percentage errors (0.00452, 0.01566, and 0.00809%), compared to the average percentage errors of three available formulas (0.01497, 0.27561, and 0.07268%). The agreement between the desired gains and the computed gains of the horns designed by using the improved formulas is very good, having average percentage errors of approximately 0.0017–0.0063%. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 239–245, 2003.     

Inhibition of the corrosion of stainless steel by poly-N-vinylimidazole and N-vinylimidazole

In this study, we investigated the inhibition of the corrosion of stainless steel (SS) in acidic solution by N-vinylimidazole monomer (NVI) and poly-N-vinylimidazole (PNVI). First, we have synthesized a polymer sample of PNVI from the monomer NVI. A stainless steel electrode was coated with this polymer as a thin film by dipping method. Corrosion rates of SS electrodes coated with PNVI films of different thicknesses were determined and compared with the results of the bare electrode in acidic solution. Corrosion rates of the bare SS electrodes were also compared with the rates in the presence of monomer and polymer, respectively, in the acidic solution. The corrosion currents were obtained by Tafel extrapolation from anodic and cathodic polarization curves. Electrochemical impedance spectroscopy (EIS) measurements were also carried out. Values of percent inhibition, wetted area and porosity were obtained for SS electrodes coated with PNVI films of different thicknesses.     

Novel phthalocyanines containing substituted salicyclic hydrazone-1,3-thiazole moieties: Microwave-assisted synthesis, spectroscopic characterization, X-ray structure and thermal characterization

Novel, metal-free and metallo(Cu, Co, Ni, Zn, Pb and Mn)phthalocyanine compounds were synthesized by exposure to microwave irradiation and the products purified. The newly prepared compounds were characterized using elemental analyses, IR, ¹H/¹³C NMR, ¹H–¹H COSY measurements, MS, UV–vis spectroscopy and DTA/TG analysis. The electronic spectra exhibited an intense π → π* transition with characteristic Q and B bands of the phthalocyanine core, as expected. All decomposition products obtained from DTA/TG analysis were identified; it was found that the thermal stability of each phthalocyanine compound followed the order: MnPc < Metal-free < ZnPc < PbPc < CuPc < CoPc < NiPc.     

Effect of particles and bioflocculation on ultraviolet disinfection of Escherichia coli

Presence of particles is known to decrease the effectiveness of ultraviolet (UV) disinfection by shielding the targeted microorganisms from UV light. This study aims to provide an in-depth understanding on the effect of particles and flocs on UV disinfection by using a stable, well-defined and well-controlled synthetic system that can simulate the bioflocculation of particles and microorganisms in water and wastewater samples. The synthetic system was created by using Escherichia coli, latex particles (1, 3.2, 11, 25, and 45 μm), alginate, and divalent cations; and the bioflocculation of particles was achieved naturally, as it would occur in the environment, without using chemical coagulants. E. coli was quantified before and after UV disinfection using membrane filtration. Even in the absence of particles, some of the self-aggregated E. coli could survive a UV dose of 90 mJ/cm². E. coli inactivation levels measured in the presence of particles were lower than the inactivation levels measured in the absence of particles. At low UV doses (<9 mJ/cm²), neither particle size nor degree of flocculation had a significant effect on the inactivation of E. coli. Particle size had a significant effect on the inactivation of E. coli only at high UV doses (80 mJ/cm²), and larger particles (e.g., 25 μm) protected bacteria more compared to smaller particles (e.g., 3.2 and 11 μm). What size of particles flocs were made of (3.2, 11, and 25 μm) did not make a significant difference on the inactivation levels of E. coli. For 3.2 μm particles, there was no significant difference in E. coli inactivation between non-flocculated and flocculated samples at any UV dose. For 11 and 25 μm particles, there was a significant difference in E. coli inactivation between non-flocculated and flocculated samples at 80 mJ/cm². Degree of flocculation became a significant factor in determining the number of surviving bacteria only at high UV doses and only for larger particles.     

Antenna array pattern nulling by controlling both amplitude and phase using modified touring ant colony optimization algorithm

This paper presents an efficient method, based on the modified touring ant colony optimization algorithm, for null steering of linear antenna arrays by controlling both the amplitude and the phase of array elements. The maximum sidelobe level, the null depth level and the dynamic range ratio are taken into account in the pattern synthesis. Simulation results for Chebyshev patterns with the imposed single, multiple and broad nulls are given to show the effectiveness of the proposed method.     

Cheap Joint Probabilistic Data Association with Adaptive Neuro-Fuzzy Inference System State Filter for Tracking Multiple Targets in Cluttered Environment

The cheap joint probabilistic data association (CJPDA) with the adaptive neuro-fuzzy inference system state filter (ANFISSF) is presented for tracking multiple targets in the presence of low and high cluttered environments. The state update step of the CJPDA filter (CJPDAF) is realized with the ANFISSF instead of Kalman filter. The adaptive neuro-fuzzy inference system (ANFIS) has the advantages of expert knowledge of fuzzy inference system and learning capability of neural networks. A hybrid learning algorithm, which combines the least square method and the backpropagation algorithm, is used to identify the parameters of ANFIS. The tracks estimated by using the method proposed in this paper for different tracking scenarios are in very good agreement with the original tracks.     

Neural models for quasi-static analysis of conventional and supported coplanar waveguides

Neural models based on multilayered perceptrons (MLPs) for computing the effective permittivities and the characteristic impedances of both the conventional coplanar waveguides (CCPWs) and the supported coplanar waveguides (SCPWs) are presented. Six learning algorithms, Levenberg–Marquardt (LM), Bayesian regularization (BR), quasi-Newton (QN), scaled conjugate gradient (SCG), conjugate gradient of Fletcher–Powell (CGF), and resilient propagation (RP), are used to train the MLPs. The results of neural models presented in this paper are compared with the results of the experimental works, the conformal mapping technique (CMT), the spectral domain approach (SDA), and three commercial electromagnetic simulators such as IE3D, CAPIND2D, and MMICTL. The neural results are in very good agreement with the theoretical and experimental results. When the performances of neural models are compared with each other, the best result is obtained from the MLPs trained by the LM algorithm.     

Ozonation as an Environmentally Friendly Method to Decolorize the Leather Products

In this study, ozonation as an environmentally friendly bleaching method was studied for decolorization of leather products. The effect of ozonation time (3, 5, 10, 15 and 30 min) and water pick-up value (WPV) (0%, 20%, 40%, 60%, 80% and 100%) were investigated on decolorization effect. For this aim, the color measurement and tensile strength tests were performed, and also structural changes were determined by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) after ozonation process. The results of color measurements showed that 30 min for ozonation and 60% WPV were optimum parameters to obtain maximum decolorization effect. SEM images of the ozonated leathers showed some deformations on the collagen fibers and resulted with the slightly decreases in tensile strength of the products. On the other hand, decreases in the tensile strength values were not statistically important levels.