All-pass filtering in iterative learning control

In iterative learning control (ILC), it is highly desirable to have a learning compensator with a unit-gain for all frequencies, in order to avoid noise amplification and learning speed degradation during the learning process. In this paper, we show that the realization of a unit-gain compensator is straightforward in ILC, using both forward and backward filtering. As an illustrative example, a unit-gain derivative is proposed to overcome the drawbacks of the conventional derivative. The proposed scheme is equivalent to an all-pass unit-gain phase shifter; the forward filtering uses a 0.5-order derivative and the backward filtering employs a 0.5-order integral. The all-pass phase shifter is deployed in a unit-gain D-type ILC. The advantages of the unit-gain feature are demonstrated by some experimental results on a robot manipulator.     

Adenine functionalized antibacterial PVC with both photo and thermal stability

Adenine was used as a precursor to obtain antibacterial poly(vinyl chloride) (PVC). Adenine functionalized PVC has been prepared, characterized, and its antibacterial activity was evaluated. Chemical modification reaction of PVC was performed with adenine in two molar ratios (2:1 and 4:1). Fourier-transform infrared spectroscopy and ¹HNMR spectroscopic analyses confirmed the chemical structure of the adenine-modified PVC and indicated the incorporation of adenine molecule in the backbone chains of PVC. Photostability of the prepared modified PVC was determined by measuring the changes in molecular weights using Gel permeation chromatography technique as well as the extent of discoloration of UV irradiated samples while thermal stability was studied by measuring the rate of dehydrochlorination and thermogravimetric analysis. Morphological investigation in terms of scanning electron microscopy was studied. Antibacterial activities of the two modified PVC samples were investigated against two types of Gram-positive bacterial strains (Bacillus subtitles, Staphylococcus aurous, and Streptococcus faecalis) while the other types (Escherichia coli, Neisseria gonorrhea, and Pseudomonas aeruginosa) represented the Gram-negative type bacteria. Antibacterial activity of PVC-adenine blend was also investigated for comparison. Minimum inhibition concentration was performed for some PVC samples under study.     

Characterization of the highest optically active fraction of shale oil

A shale oil sample from an above-ground 150 ton retort, designed to simulate the in-situ retort process, was vacuum distilled to obtain narrow distillate fractions. The optical rotation was measured for each distillate cut. The fraction with the highest optical rotation (470 °–485 °C) was subjected to elution chromatography using hexane, benzene and methanol, respectively. The resulting saturated fraction (hexane cut) was investigated by computerized gas chromatography-mass spectrometry. Three steranes, four pentacyclic triterpanes and five normal alkanes were identified, and the partial structures of two other compounds have been suggested.     

The Ce3+ → Tb3+ transfer in phosphate host lattices

A Ce³⁺ → Tb³⁺ transfer has been shown to appear in various phosphates belonging to different structural types and particularly in some new compounds: Na₃Ln(PO₄)₂:Ce, Tb; Na_xSr_3?2xLn_x(PO₄)₂:Ce, Tb and KCaLn(PO₄)₂:Ce, Tb.The presence of [PO₄ groups, in which the P-O bonds are strongly covalent, leads to a relatively weak crystal field at the rare-earth sites. The best overlapping between cerium emission and terbium excitation spectra is obtained for phosphates containing alkali ions. This result can be explained by a lowering of the emitting level of the cerium 5d configuration due to stronger covalency of the CeO bond and to an increasing crystal field at the rare-earth sites.     

How significant is the assumption of the uniform channel phase distribution on the performance of spatial multiplexing MIMO system?

Spatial multiplexing (SMX) multiple-input multiple-output (MIMO) systems are promising candidates to enhance the achievable throughput and the overall spectral efficiency in future wireless systems. Performance studies of these systems over different channel conditions assume simplified models for the channel phase distribution. This paper highlights the impact of the channel phase distribution assumption on the performance of SMX MIMO systems. The Nakagami-m and the \(\eta -\mu\) fading channels are considered in this study. In existing literature, performance studies of SMX MIMO systems over Nakagami-m fading channel assume uniform phase distribution. Though, it has been reported recently that the Nakagami-m channel phase distribution is not uniform. In this article, we show that the assumption of the channel phase distribution has a major impact on the performance of SMX MIMO systems. The obtained results demonstrate that the performance of SMX MIMO systems significantly varies with different channel phase distributions. Furthermore, it is shown that uniform assumption of channel phase distribution is incorrect and leads to erroneous conclusions. Detailed performance analysis for more accurate channel models are provided and results are sustained through Monte-Carlo simulations.     

Synthesis and characterization of Co-doped nano-TiO<Subscript>2</Subscript> through co-precipitation method for photocatalytic activity

The aim of this work was synthesis and investigation of various properties of Co-doped titanium dioxide nanostructures. Synthesis was conducted by the co-precipitation method using cobalt nitrate and titanium isopropoxide as a precursor, followed by thermal treatment at a temperature of 500 °C. The materials were fully characterized using several techniques (X-ray diffraction XRD, SEM, FTIR, TGA/DTA, UV–Vis diffuse reflectance DRS and photoluminescence). However, dopant has no effect on XRD pattern of the host but it can influence on the various characteristics of host such as optical and electrical properties. The scanning electron microscopy was used to detect the morphology of synthesized nanoparticles which sizes changed with the altitude in the doping concentration to 6%. FTIR spectra exhibit broad peaks where anatase phases of TiO₂ demonstrate very sharp UV–Vis band gap results showed the reduction in band gap from from 3.21 eV, for undoped TiO₂, to 2.74 eV, for Co doped 6% TiO₂. The photocatalytic activity of the samples were studied based on the degradation of methyl orange as a model compound, where the results showed that Co doped 6% TiO₂ a good photocatalytic activity.     

Robust Prediction of the Bandwidth of Metamaterial Antenna Using Deep Learning

The design of microstrip antennas is a complex and time-consuming process, especially the step of searching for the best design parameters. Meanwhile, the performance of microstrip antennas can be improved using metamaterial, which results in a new class of antennas called metamaterial antenna. Several parameters affect the radiation loss and quality factor of this class of antennas, such as the antenna size. Recently, the optimal values of the design parameters of metamaterial antennas can be predicted using machine learning, which presents a better alternative to simulation tools and trial-and-error processes. However, the prediction accuracy depends heavily on the quality of the machine learning model. In this paper, and benefiting from the current advances in deep learning, we propose a deep network architecture to predict the bandwidth of metamaterial antenna. Experimental results show that the proposed deep network could accurately predict the optimal values of the antenna bandwidth with a tiny value of mean-square error (MSE). In addition, the proposed model is compared with current competing approaches that are based on support vector machines, multi-layer perceptron, K-nearest neighbors, and ensemble models. The results show that the proposed model is better than the other approaches and can predict antenna bandwidth more accurately.     

Detection of Impending Vehicle Rollover with Road Bank Angle Consideration Using a Robust Fuzzy Observer

 This article describes a method of vehicle dynamics estimation for impending rollover detection. We estimate vehicle dynamic states in presence of the road bank angle as a disturbance in the vehicle model using a robust observer. The estimated roll angle and roll rate are used to compute the rollover index which is based on the prediction of the lateral load transfer. In order to anticipate rollover detection, a new method is proposed to compute the time to rollover (TTR) using the load transfer ratio (LTR). The nonlinear model, deduced from the vehicle lateral and roll dynamics, is represented by a Takagi-Sugeno (T-S) fuzzy model. This representation is used to account for the nonlinearities of lateral cornering forces. The proposed T-S observer is designed with unmeasurable premise variables to cater for non-availability of the slip angles measurement. The proposed approach is evaluated using CarSim simulator under different driving scenarios. Simulation results show good efficiency of the proposed T-S observer and the rollover detection method.     

A Predictive Model of the Optimal Tool Edge Geometry for Veneer Cutting Processes

Abstract

Veneer cutting is a specific machining process, where the chip is the final product. The objective of this article is to investigate on the optimal tool edge geometry, using particle swarm optimization (PSO) algorithm, to obtain the desired veneer thickness. The challenge is to maintain the best quality of veneer product with the control of pre-splitting condition and thickness variation. Numerical results obtained from PSO algorithm are compared and verified with the experimental ones. The proposed model allows us to predict the characteristic tool angles for different chip thicknesses and friction coefficients. For chip thickness range greater than 2?mm, the presplitting condition is no longer satisfied, as in the case of rotary peeling veneer, the need of using pressure bar becomes primordial.