Adaptive control of permanent magnet synchronous machines with disturbance estimation

In this paper,an adaptive control scheme is introduced for permanent magnet synchronous machines (PMSMs)as an alternative to classical control techniques.The adaptive control strategy capitalizes on the machine’s inverse dynamics to achieve accurate tracking by using an observer to approximate disturbance in the form of friction and load torque.The controller’s output is then fed to a space vector pulse width modulation(SVPWM)algorithm to produce duty cycles for the inverter.The control scheme is validated through a set of simulations on an experimentally validated PMSM model.Results for different situations highlight its high speed tracking accuracy and high performance in compensating for friction and load disturbances of various magnitudes.     

Determining trust in media-rich websites using semantic similarity

Significant growth of multimedia content on the World Wide Web (or simply ??Web??) has made it an essential part of peoples lives. The web provides enormous amount of information, however, it is very important for the users to be able to gauge the trustworthiness of web information. Users normally access content from the first few links provided to them by search engines such as Google or Yahoo!. This is assuming that these search engines provide factual information, which may be popular due to criteria such as page rank but may not always be trustworthy from the factual aspects. This paper presents a mechanism to determine trust of websites based on the semantic similarity of their multimedia content with already established and trusted websites. The proposed method allows for dynamic computation of the trust level of websites of different domains and hence overcomes the dependency on traditional user feedback methods for determining trust. In fact, our method attempts to emulate the evolving process of trust that takes place in a user??s mind. The experimental results have been provided to demonstrate the utility and practicality of the proposed method.     

Solid-state NMR study of N labelled polyaniline upon reaction with DPPH

The quantitative investigation of the radical scavenging properties of polyaniline (PANI) upon reaction with excess of the stable DPPH radical (a 4:1 ratio of DPPH to aniline units in the polymer) was carried out using ¹⁵N and ¹³C solid state NMR spectroscopy. During the process the polyaniline was oxidised so that the imine content increased from 45 to 65%. The extent of oxidation measured by NMR was confirmed by N1s XPS analysis. However, within a 30 min reaction time, about 85% of the DPPH radicals were scavenged as monitored by the decay in its EPR signal. This is about 20 times greater than the fraction of DPPH required to oxidize PANI from an imine content of 45-65%. An identification of further redox processes is required to explain the high degree of radical scavenging. At the same time, there was no evidence of significant chemical binding or trapping of DPPH in the PANI structure.     

A New Risk Assessment Approach for Cloud Consumer

The cloud computing introduces several changes in technology that have resulted a new ways for cloud providers to deliver their services to cloud consumers mainly in term of security risk assessment, thus, adapting a current risk assessment tools to cloud computing is a very difficult task due to its several characteristics that challenge the effectiveness of risk assessment approaches. Consequently, there is a need of risk assessment approach adapted to cloud computing. With such an approach, the cloud consumers can be guaranteed the effectiveness of data security and the cloud providers can win the trust of their cloud consumers. This paper requires the formalization of risk assessment method for conventional system as fundamental steps towards the development of flexible risk assessment approach regarding cloud consumers.     

Filling of very deep, wide trenches by BenzoCycloButene polymer

A process for deep trench filling by BenzoCycloButene (BCB) polymer is explored. Deep trenches with 100-μm depth and different aspect ratios from 1.4 to 20 have been successfully filled by BCB. Besides, chemical mechanical polishing (CMP) of BCB is studied with the main goals of smoothing surface topography of substrate after BCB filling and removing excess BCB coating which may be necessary in some applications. Removal rate for BCB, V _RR, of about 0.24 μm/min has been achieved for hard cured BCB films using acid slurry. After CMP, the BCB layer showed a roughness of about 1.36 nm (Rq, measured by atomic force microscopy, AFM).     

Metaheuristics and exact methods to solve a multiobjective parallel machines scheduling problem

This paper deals with a multiobjective parallel machines scheduling problem. It consists in scheduling n independent jobs on m identical parallel machines. The job data such as processing times, release dates, due dates and sequence dependent setup times are considered. The goal is to optimize two different objectives: the makespan and the total tardiness. A mixed integer linear program is proposed to model the studied problem. As this problem is NP-hard in the strong sense, a metaheuristic method which is the second version of the non dominated sorting genetic algorithm (NSGA-II) is proposed to solve this problem. Since the parameters setting of a genetic algorithm is difficult, a fuzzy logic controller coupled with the NSGA-II (FLC-NSGA-II) is therefore proposed. The role of the fuzzy logic is to better set the crossover and the mutation probabilities in order to update the search ability. After that, an exact method based on the two phase method is also developed. We have used four measuring criteria to compare these methods. The experimental results show the advantages and the efficiency of FLC-NSGA-II.     

Cryo-X-ray analysis-A novel tool to better understand the physicochemical reactions at the bioglass/biological fluid interface

The present study deals with the short-term physicochemical reactions at the interface between bioactive glass particles [55SiO(2)-20CaO-9P(2)O(5)-12Na(2)O-4MgO. mol%] and biological fluid (Dulbecco Modified Eagle's Medium (DMEM)). The physicochemical reactions within the interface are characterized by scanning transmission electron microscopy (TEM) (STEM) associated with Energy-dispersive X-ray spectroscopy (EDXS). Microanalysis of diffusible ions such as sodium, potassium, or oxygen requires a special care. In the present investigation the cryo-technique was adopted as a suitable tool for the specimen preparation and characterization. Cryosectioning is essential for preserving the native distribution of ions so that meaningful information about the local concentrations can be obtained by elemental microanalysis. The bioglass particles immersed in biological fluid for 24 h revealed five reaction stages: (i) dealkalization of the surface by cationic exchange (Na(+), Ca(2+) with H(+) or H(3)O(+)); (ii) loss of soluble silica in the form of Si(OH)(4) to the solution resulting from the breakdown of Si--O--Si bonds (iii); repolymerization of Si(OH)(4) leading to condensation of SiO(2)); (iv) migration of Ca(2+) and PO(4) (3-) to the surface through the SiO(2)-rich layer to form CaO-P(2)O(5) film; (v) crystallization of the amorphous CaO-P(2)O(5) by incorporating OH-- or CO(3) (2-) anions with the formation of three different surface layers on the bioactive glass periphery. The thickness of each layer is approximately 300 nm and from the inner part to the periphery they consist of Si--OH, which permits the diffusion of Ca(2+) and PO(4) (3-) ions and the formation of the middle Ca--P layer, and finally the outer layer composed of Na--O, which acts as an ion exchange layer between Na(+) ions and H(+) or H(3)O(+) from the solution.     

Structure of the ion-rich phase in DVB cross-linked graft-copolymer proton-exchange membranes

We report on correlations between the proton conductivity, the water swelling and the dry-state morphology of ETFE-g-poly(sulfonated styrene-co-DVB) proton-exchange membranes (PEMs). We focus on the influence of the systematically varied monomer composition. Especially, the impact of the DVB cross-linker on the ion-rich phase aggregated in the dry PEM is studied by small-angle X-ray scattering. A modified hard-sphere fluid model describing the ion-rich phase is applied to interpret the observed scattering function. We find hereby that the size and number density of the ion-rich domains decrease with increasing cross-link level. Consequently, the distance between the ion-rich domains is proportional to the cross-link level. The total volume fraction of water in the hydrated membrane is proportional to the overall volume fraction of the ion-rich phase, and the number of water molecules per ion-rich aggregate is inversely proportional to the level of cross-linking. We show that there is a clear correlation between the structure of the ion-rich phase formed in the dry state and the proton conductivity of the hydrated membrane: beyond a threshold, indicating the onset of percolation of the aqueous network, the conductivity is proportional to the hydration level and inversely proportional to the mean distance between the ion-rich domains.     

Can the dietary element content of virgin argan oils really be used for adulteration detection?

Levels of eight dietary elements were assessed by ICP-AES in virgin edible and beauty argan oil samples prepared from four remote locations of the argan forest, and over a three-year period. The data showed sufficiently little variability to assess that all argan oil samples present, in terms of dietary elements, a similar composition, independently from the tree location within the argan forest. Therefore, adulteration detection by trace element analysis in edible and beauty argan oil is a method that can be generalised.     

An exploration of corrosion inhibition of mild steel in sulphuric acid solution through experimental study and Monte Carlo simulations

Abstract

4-[4-(1H-imidazol-1-yl)methyl)-1H-1,2,3-triazol-1-yl]methylbenzophenone (ITBP) and 4[4-(1H-1,2,4-triazol-1-yl)methyl)-1H-1,2,3-triazol-1-yl]methylbenzophenone (TTBP) are synthesized as new heterocyclic compounds of the triazole derivative family and tested successfully as potential inhibitors for MS in 1?M H₂SO₄ corrosive medium by using gravimetric analysis, electrochemical impedance spectroscopy, potentiodynamic polarization, and energy dispersive X-ray spectroscopy (EDX). Polarization curves show that the tested inhibitors are mixed-type inhibitors. Scanning electron microscopy (SEM) affirmed the existence of an adsorbed film on the steel surface. Monte Carlo simulations were in excellent agreement with the experimental tests.

Abbreviation: PDP: Potentiodynamic Polarization; EIS: Electrochemical impedance spectroscopy; DFT: Density functional theory; MC: Monte Carlo