Reliability improvement of distribution systems using SSVR

This paper presents a reliability assessment algorithm for distribution systems using a Static Series Voltage Regulator (SSVR). Furthermore, this algorithm considers the effects of Distributed Generation (DG) units, alternative sources, system reconfiguration, load shedding and load adding on distribution system reliability indices. In this algorithm, load points are classified into 8 types and separated restoration times are considered for each class. Comparative studies are conducted to investigate the impacts of DG and alternative source unavailability on the distribution system reliability. For reliability assessment, the customer-oriented reliability indices such as SAIFI, SAIDI, CAIDI ASUI and also load- and energy-oriented indices such as ENS and AENS are evaluated. The effectiveness of the proposed algorithm is examined on the two standard distribution systems consisting of 33 and 69 nodes. The best location of the SSVR in distribution systems is determined based on different reliability indices, separately. Results show that the proposed algorithm is efficient for large-scale radial distribution systems and can accommodate the effects of fault isolation and load restoration.     

Spectral analysis methods for vehicle interior vibro-acoustics identification

Noise has various effects on comfort, performance and health of human. Sound are analysed by human brain based on the frequencies and amplitudes. In a dynamic system, transmission of sound and vibrations depend on frequency and direction of the input motion and characteristics of the output. It is imperative that automotive manufacturers invest a lot of effort and money to improve and enhance the vibro-acoustics performance of their products. The enhancement effort may be very difficult and time-consuming if one relies only on ‘trial and error’ method without prior knowledge about the sources itself. Complex noise inside a vehicle cabin originated from various sources and travel through many pathways. First stage of sound quality refinement is to find the source. It is vital for automotive engineers to identify the dominant noise sources such as engine noise, exhaust noise and noise due to vibration transmission inside of vehicle. The purpose of this paper is to find the vibro-acoustical sources of noise in a passenger vehicle compartment. The implementation of spectral analysis method is much faster than the ‘trial and error’ methods in which, parts should be separated to measure the transfer functions. Also by using spectral analysis method, signals can be recorded in real operational conditions which conduce to more consistent results. A multi-channel analyser is utilised to measure and record the vibro-acoustical signals. Computational algorithms are also employed to identify contribution of various sources towards the measured interior signal. These achievements can be utilised to detect, control and optimise interior noise performance of road transport vehicles.     

An improved topology of electronic ballast with wide dimming range,PFC and low switching losses using PWM-controlled soft-switching inverter

This paper presents a novel improved topology of voltage-fed soft-switching LC_rC_dc series–parallel quasi-resonant inverter with a constant-frequency for electronic ballast applications. This new topology introduces a low-cost solution to reduce switching losses to achieve high-efficiency ballast. A symmetrical pulse wide modulation (PWM) control scheme is implemented to regulate a wide range of output power. Switching losses effect on ballast efficiency is discussed through experimental point of view. In this discussion, an improved topology in which accomplishes soft-switching operation over a wide power regulation range is proposed. Energy consumption of this new circuit is decreased by using reverse recovery attribute. Additionally, a power-factor correction (PFC) circuit is employed to make the line current follow naturally the sinusoidal line voltage waveform.     

The inhibition effect of the new Schiff base,namely 2,2′‐[bis‐N(4‐choloro benzaldimin)]‐1,1′‐dithio against mild steel corrosion

2,2′‐[bis‐N(4‐choloro benzaldimin)]‐1,1′‐dithio has been synthesized and its inhibiting action on the corrosion of mild steel in 0.5 M sulfuric acid was investigated by various corrosion monitoring techniques, such as weight loss and potentiodynamic polarization techniques. The experimental results suggest that this compound is a good corrosion inhibitor for mild steel and the inhibition efficiency increases with the increase in inhibitor concentration. This organic compound is a mixed type inhibitor in the acid solution, and its adsorption on the mild steel surface is also found to obey the Langmuir adsorption isotherm.     

Impact sédimentaire des travaux d'aménagement de l'estuaire de la Loire

The planning works realized in the Loire estuary (France) during the course of the twentieth century have brought about an important inflow of sea water to this site. The consequences can be observed through important changes in the location of the extreme limits of both the dynamic tide and the salinity front at 0.5‰; the dynamic tide has progressed from 63?km from the river mouth in 1903 to 100?km in 1992 and the salinity front from 38?km in 1948 to 70?km in 1991. Modifications of the hydraulic conditions have also affected the dynamics of the cohesive sediments present in the estuary. The purpose of this study is to determine the impact of the past and future planning works in the Loire estuary on the erosion and deposition of cohesive sediments in relation to hydraulic conditions. The principal sedimentary processes (transportation, deposition, settlement, erosion) are simulated by simplified models from measurements carried out both in situ and in the laboratory. The dynamics of the cohesive sediment in the Loire estuary are linked with the fortnightly cycle of the tide as follows: when the tidal coefficient falls below 70, almost all the suspended matter is quickly deposited and collects near the estuary bed to form a lens-shaped body of fluid mud which consolidates during 6?days of neap tides. Finally, as soon as the tide coefficient rises above 75, this body of fluid mud is taken again into suspension and only the fraction that was highly concentrated in the course of the settlement remains on the bottom. The sediments remaining on the estuary bed in the course of a fortnightly cycle of the tide represent the residual sedimentation rate over this period. Knowledge of the maximum tide current velocities in the estuary permits the determination of the maximum hydrodynamic stress on the bottom and the critical concentration of the mud susceptible to being eroded by this current, taking into account the yield stress of the mud. In other respects, the quantity of mud that is greater than this critical concentration per surface unit and time unit can be calculated according to a theoretical model developed by Sanchez and Grovel. This methodology allows the evaluation of the residual sedimentation rate representing a layer of 0.08?m per year in front of the harbour of Montoir for the hydraulic conditions of 1976, with a maximum current velocity on the surface of 2.40?m?s^–1. Following the dredging works realized between St-Nazaire and Donges after 1976, the level of the bottom has changed from –10.00 to –13.25?m (with respect to the hydrographic datum). These works have brought about a reduction in maximum velocities of 15% and an increase in the residual sedimentation rate of about 100%. This increase is in agreement with the theoretical estimation of this study. This study also describes the high sedimentation rate observed in a locally dredged berth and located in the zone of the estuary where a lens-shaped body of fluid mud is formed during slack tides. The sedimentation rate depends then on the frequency of the dredging works because the dredged zone can be filled up in a few days. Finally, a methodology is developed in order to estimate the erosion rate induced by an increase in current velocities. This methodology takes into account the vertical concentration gradient in the bed resulting from consolidation, the hydrodynamic stress linked to current velocity, the yield stress of sediment which varies with concentration and the critical hydrodynamic stress for erosion estimated from experimental measurements in laboratory. All the methodologies presented in this paper have been applied only to the estuary of the river Loire. Application to any other similar site is possible after laboratory experiments on local sediments in order to adjust the behavioural laws used to evaluate the permeability coefficient, the effective stress and the yield stress. This study shows that knowledge of hydraulic conditions and local sedimentary processes is very important for predicting the impact of planning works in an estuary.     

A hybrid computer simulation-adaptive neuro-fuzzy inference system algorithm for optimization of dispatching rule selection in job shop scheduling problems under uncertainty

The International Journal of Advanced Manufacturing Technology - Unstable environment of industrial systems is a source of various uncertainties in production features such as processing times....     

An innovative approach to electro-oxidation of dopamine on titanium dioxide nanotubes electrode modified by gold particles

Au/TiO₂/Ti electrodes were prepared by galvanic deposition of gold particles from an acidic bath containing KAu(CN)₂ in the presence of a citrate buffer onto TiO₂ nanotubes layer on titanium substrates. Titanium oxide nanotubes were fabricated by anodizing titanium foil in a DMSO fluoride-containing electrolyte. The morphology and surface characteristics of Au/TiO₂/Ti electrodes were investigated using scanning electron microscopy and energy-dispersive X-ray, respectively. The results indicated that gold particles were homogeneously deposited on the surface of TiO₂ nanotubes. The nanotubular TiO₂ layers consist of individual tubes of about 40–80 nm diameters. The electro-catalytic behavior of Au/TiO₂/Ti electrodes for the dopamine electro-oxidation was studied by cyclic voltammetry and differential pulse voltammetry. The results showed that Au/TiO₂/Ti electrodes exhibit a considerably higher electro-catalytic activity toward the oxidation of dopamine. The catalytic oxidation peak current showed a linear dependence on dopamine concentration and a linear calibration curve was obtained in the concentration range of 0.5–2.5 mM of dopamine.     

3-D simulation of particle filtration in electrospun nanofibrous filters

Virtual 3-D geometries resembling the internal microstructure of electrospun fibrous materials are generated in this work to simulate the pressure drop and collection efficiency of nanofibrous media when challenged with aerosol particles in the size range of 25 to 1000 nm. In particular, we solved the air flow field in the void space between the fibers in a series of 3-D fibrous geometries with a fiber diameter in the range of 100 to 1000 nm and a Solid Volume Fraction (SVF) in the range of 2.5 to 7.5%, using the Fluent CFD code, and simulated the flow of large and fine particles through these media using Lagrangian and Eulerian methods, respectively. Particle collection due to interception and Brownian diffusion, as well as the slip effect at the surface of nanofibers, has been incorporated in the CFD calculations by developing customized C++ subroutines that run in the Fluent environment. Particle collection efficiency and pressure drop of the above fibrous media are calculated and compared with analytical/empirical results from the literature. The numerical simulations presented here are believed to be the most complete and realistic filter modeling published to date. Our simulation technique, unlike previous studies based on oversimplified 2-D geometries, does not need any empirical correction factors, and can be used to directly simulate pressure drop and efficiency of any fibrous media.     

Solubility analysis of clozapine and lamotrigine in supercritical carbon dioxide using static system

The experimental techniques used to obtain the solubilities of clozapine and lamotrigine in supercritical carbon dioxide include a simple static technique. The solubility measurements were performed at temperatures between 318 and 348 K and pressures between 121.6 and 354.0 bar. These chemicals have solubilities with values ranging from 3.6 × 10⁻⁶ to 4.2 × 10⁻⁵ (clozapine) and 1 × 10⁻⁶ to 6 × 10⁻⁵ (lamotrigine) mole fraction. The solubility data were correlated using four semi-empirical density-based models (Chrastil, Bartle, K-J and M-T models). Correlation of the results shows good self-consistency of the data obtained with the Bartle model for clozapine with an overall average absolute relative deviation (AARD%) of 11.21. The calculated results with each four models show satisfactory agreement with the experimental data for lamotrigine with an overall AARD% 11.72, 8.99, 2.75, 3.86 for Chrastil, K-J, Bartle, M-T models, respectively. Using the correlation results, the heat of drug-CO₂ solvation and that of drug vaporization were approximated.