Experimental analysis of a novel ozone generator configuration for use in water treatment applications

Volume dielectric barrier discharge (VDBD) is considered to be the most effective method for ozone generation. This paper reports a comparison between a simple ‘classic’ VDBD cylindrical ozone generator and a ‘metallic-mesh-filled-air-gap cylindrical dielectric barrier discharge’ model. The obtained results show that although the majority of ozone generators are of the volume discharge type, the novel volume discharge model has provided better results in terms of ozone generation and energy efficiency. A skid was built by using eight proposed generators and was successfully used for wastewater treatment.     

A similarity measure for the negotiation in web services

This paper presents a new negotiation approach integrating a similarity-based metric to measure the client’s satisfaction level by quantifying the correspondence between the features required by the client and the ones proposed by the service. This negotiation process is integrated within an adaptation platform for multimedia presentations supporting different types of terminals. The negotiation and adaptation processes are based on the management of user’s and service’s profiles. We also propose an extension of the SIP protocol to ensure the communication between the client and the server by defining new functionalities.     

Functionality at the edge: designing scalable multiservice ATMnetworks

ATM offers the capability of consolidating multiple services onto a common backbone network, thereby reducing network management complexity, improving utilization, and lowering cost. As ATM networks grow, a virtual path connection (VPC) network core is often provisioned to reduce the number of connections to provide scalability for network management and performance. Provisioning a VPC network core raises a number of issues, especially related to the performance of bursty non-real-time connections. This article discusses these issues and how the functionality of ATM can best address them. It is shown that employing low-loss flow-controlled ABR VPCs to carry non-real-time traffic can provide significant gains in terms of performance as well as improved throughput for a given amount of buffering in the network core. The flow-controlled VPC enables the complexities of virtual channel connection- (VCC)-level congestion control, fairness, and isolation to be pushed to the network edge where lower speeds allow this functionality to be performed more cost effectively     

Study of flash evaporated CuIn1 − xGaxTe2 (x = 0, 0.5 and 1) thin films

CuIn_1 − xGa_xTe₂ thin films with x = 0, 0.5 and 1, have been prepared by flash evaporation technique. These semiconducting layers present a chalcopyrite structure. The optical measurements have been carried out in the wavelength range 200-3000 nm. The linear dependence of the lattice parameters as a function of Ga content obeying Vegard's law was observed. The films have high absorption coefficients (4 · 10⁴ cm^− 1) and optical band gaps ranging from 1.06 eV for CuInTe₂ to 1.21 eV for CuGaTe₂. The fundamental transition energies of the CuIn_1 − xGa_xTe₂ thin films can be fitted by a parabolic equation namely E_g1(x) = 1.06 + 0.237x − 0.082x². The second transition energies of the CuInTe₂ and CuGaTe₂ films were estimated to be: E_g2 = 1.21 eV and E_g2 = 1.39 eV respectively. This variation of the energy gap with x has allowed the achievement of absorber layers with large gaps.     

Numerical and analytical investigation of the size-dependency of the FPZ length in concrete

The main objective of this paper is to study the size effect on the fracture characteristics in concrete structures. The numerical investigation is based on a mesoscale modeling approach. Analytically, two size effect laws are investigated: the classical Ba?ant SEL and a new size effect law based on the enrichment of the stress field on the crack tip. The mesoscopic approach is used to study the evolution of the tangential stress along the crack path in order to investigate the fracture process zone variation during the cracking process. In addition, different analytical governing equations are used to evaluate the size-dependency of the FPZ length.     

Preparation of Sb:SnO2 thin films and its effect on opto-electrical properties

The present study focuses on pure and antimony (Sb)-doped tin oxide thin film and its influence on their structural, optical, and electrical properties. Both undoped and Sb-doped SnO₂ thin films have been grown by using simple, inexpensive pyrolysis spray technique. The deposition temperature was optimized to 450 °C. X-ray diffractions pattern have revealed that the films are polycrystalline and have tetragonal rutile-type crystal structure. Undoped SnO₂ films grow along (110) preferred orientation, while the Sb-doped SnO₂ films grow along (200) direction. The size of Sb-doped tin oxide crystals changes from 26.3 to 58.0 nm when dopant concentration is changed from 5 to 25 wt%. The transmission spectra revealed that all the samples are transparent in the visible region, and the optical bandgap varies between 3.92 and 3.98 eV. SEM analysis shows that the surface morphology and grain size are affected by the doping rate. All the films exhibit a high transmittance in the visible region and show a sharp fundamental absorption edge at about 0.38–0.40 nm. The maximum electrical conductivity of 362.5 S/cm was obtained for the film doped with 5 wt% Sb. However, the carrier concentration is increased from 0.708?×?10¹⁸ to 4.058?×?10²⁰ cm³. The electrical study reveals that the films have n-type electrical conductivity and depend on Sb concentration. We observed a decrease in sheet resistance and resistivity with the increase in Sb dopant concentration. For the dopant concentration of 5 wt% of Sb in SnO₂, the Rs and ρ were found minimum with the values of 88.55 (Ω cm^?2) and 2.75 (Ω cm), respectively. We observed an increase in carrier concentration and a decrease in mobility with the addition of Sb up to 25 wt%. The highest figure of merit values 2.5?×?10^–3 Ω^?1 is obtained for the 5wt% Sb, which may be considered potential materials for solar cells' transparent windows.

     

Allocating transmission loss to loads and generators through complex power flow tracing

This paper presents a new method for complex power flow tracing that can be used for allocating the transmission loss to loads or generators. Two algorithms for upstream tracing (UST) and downstream tracing (DST) of the complex power are introduced. UST algorithm traces the complex power extracted by loads back to source nodes and assigns a fraction of the complex power flow through each line to each load. DST algorithm traces the output of the generators down to the sink nodes determining the contributions of each generator to the complex power flow and losses through each line. While doing so, active- and reactive-power flows as well as complex losses are considered simultaneously, not separately as most of the available methods do. Transmission losses are taken into consideration during power flow tracing. Unbundling line losses are carried out using an equation, which has a physical basis, and considers the coupling between active- and reactive-power flows as well as the cross effects of active and reactive powers on active and reactive losses. The tracing algorithms introduced can be considered direct to a good extent, as there is no need for exhaustive search to determine the flow paths as these are determined in a systematic way during the course of tracing. Results of application of the proposed method are also presented.     

Formation control of VTOL Unmanned Aerial Vehicles with communication delays

The formation control problem of a team of Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicles (UAVs) with communication delays is addressed. Based on the extraction algorithm presented in Abdessameud and Tayebi (2010a), we propose a new design methodology that simplifies the design of formation control laws with delayed communication for this class of under-actuated systems. Three control schemes are presented that provide delay-dependent and delay-independent results with constant and time-varying communication delays. The stability of the overall closed loop system in each scheme is established using Lyapunov–Krasovskii functionals. The proposed design methodology achieves global results in terms of the position and removes the requirement of the linear-velocity measurements. Simulation results are provided to show the effectiveness of the proposed control schemes.