An accelerated sequential sampling for estimating the reliability of N-parallel systems

Kamel Rekab,Yuan Cheng 한국신뢰성학회 2013 International Journal of Reliability and Applicati Vol.14 No.2

The problem of designing an experiment to estimate the reliability of a system that has N subsystems connected in series where each subsystem n has n Tn components connected in parallel is investigated both theoretically and by simulation. An accelerated sampling sheme is introduced. It is shown that the accelerated sampling scheme is asymptotically optimal as the total number of units goes to infinity. Numerical comparisons for a system that has two subsystems connected in series where each subsystem has two components connected in parallel are also given. They indicate that the accelerated sampling scheme performs better than the batch sequential sampling scheme and is nearly optimal.

Stability in nonlinear neutral Levin-Nohel integro-differential equations

Kamel Ali Khelil,Abdelouaheb Ardjouni,Ahcene Djoudi 강원경기수학회 2017 한국수학논문집 Vol.25 No.3

In this paper we use the Krasnoselskii-Burton's fixed point theorem to obtain asymptotic stability and stability results about the zero solution for the following nonlinear neutral Levin-Nohel integro-differential equation $$ x^{\prime }(t)+\int_{t-\tau (t)}^{t}a(t,s)g\left( x(s)\right) ds+c(t)x^{\prime }(t-\tau (t))=0. $$ The results obtained here extend the work of Mesmouli, Ardjouni and Djoudi [20].

Sliding Mode Control Based DTC of Sensorless Parallel-Connected Two Five-Phase PMSM Drive System

Kamel, Tounsi,Abdelkader, Djahbar,Said, Barkat,Al-Hitmi, M.,Iqbal, Atif The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.3

This paper presents a sensorless direct torque control (DTC) combined with sliding mode approach (SM) and space vector modulation (SVM) to achieve mainly a high performance and reduce torque and flux ripples of a parallel-connected two five-phase permanent magnet synchronous machine (PMSM) drive system. In order to increase the proposed drive robustness and decrease its complexity and cost, the rotor speeds, rotor positions, fluxes as well as torques are estimated by using a sliding mode observer (SMO) scheme. The effectiveness of the proposed sliding mode observer in conjunction with the sliding mode control based DTC is confirmed through the application of different load torques for wide speed range operation. Comparison between sliding mode control and proportional integral (PI) control based DTC of the proposed two-motor drive is provided. The obtained speeds, torques and fluxes responses follow their references; even in low and reverse speed operations, load torques changes, and machines parameters variations. Simulation results confirm also that, the ripples of the torques and fluxes are reduced more than 3.33% and 16.66 %, respectively, and the speed overshoots and speed drops are reduced about 99.85% and 92.24%, respectively.

Response of Commercial Cotton Cultivars to Fusarium solani

Kamel A. Abd-Elsalam,Moawad R. Omar,Abdel-Rheem El-Samawaty,Aly A. Aly 한국식물병리학회 2007 Plant Pathology Journal Vol.23 No.2

Twenty-nine isolates of Fusarium solani, originally isolated from diseased cotton roots in Egypt, were evaluated for their ability to cause symptoms on four genetically diverse cotton cultivars. Analysis of variance showed highly significant variance among cultivars, and isolates as well as the isolate × genotype interactions were highly significant (p < 0.0001). Although most isolates showed intermediate pathogenicity, there were two groups of isolates that showed significant differences in pathogenicity on all four cultivars. None of the cultivars were found to be immune to any of the isolates. On all cultivars, there were strong significant positive correlations between dry weight and each of preemergence damping-off, survival, and plant height. Considering 75% similarity in virulence, two groups comprising a total of 29 isolates were recognized. Ninety-three percent of the isolates have the same pathogenicity patterns with consistently low pathogenicity, and narrow diversity of virulence. Isolates Fs4 and Fs5 shared the same distinct overall virulence spectrum with consistently high pathogenicity. There was no clear-cut relationship between virulence of the isolates based on reaction pattern on 4 cultivars and each of host genotype, previous crop, and geographic origin.

Implementation of phase change material for cooling load reduction: a case study for Cairo, Egypt

Kamel Joseph Alfy,Mina Ehab Mouris,Elsabbagh Ahmed Moneeb 대한설비공학회 2022 International Journal of Air-Conditioning and Refr Vol.30 No.1

Integrating a phase change material (PCM) into building envelopes can reduce energy needs in the built environment, and the consequent greenhouse emissions. This research examines the impact of PCM integrated into a traditional wall in Egypt on peak and average cooling energy consumption. A MATLAB code based on the finite volume technique using the Crank-Nicolson method for discretization is implemented. Several benchmark cases and experimental results validate the code. The time-dependent boundary conditions of the cases examined were based on the irradiance and ambient temperatures measured in Cairo, Egypt. Simulations are performed on eight different PCMs, using their real published DSC curve. The study aims to investigate the performance of each PCM at different positions, thicknesses, and wall orientations. The calculations revealed that using the proper PCM type and the proper position could decrease the average by 38.14%, Also the peak heat flux could be decreased by 58.53%.

Electrooxidation of DL-norvaline at Glassy Carbon Electrode: Approaching the Modified Electrode for Voltammetric Studies of Hydroquinone and Catechol

Kamel, Mahmoud M. The Korean Electrochemical Society 2014 Journal of electrochemical science and technology Vol.5 No.1

The DL-norvaline was electrochemically oxidized and deposited on the glassy carbon electrode surface using cyclic voltammetry (CV). The modified electrode was examined for electrochemical oxidation of hydroquinone (HQ) and catechol (CC). It exhibited good electrocatalytic ability towards their oxidation and simultaneous determination in a binary mixture using differential pulse voltammetry (DPV). The peak currents were linear to the concentration of HQ and CC, in the range from $5{\mu}M$ to $100{\mu}M$, and $4{\mu}M$ to $140{\mu}M$, respectively. The determination limits(S/N = 3) for HQ and CC were $1{\mu}M$ and $0.8{\mu}M$, respectively. The obtained modified electrode was applied to simultaneous detection of HQ and CC in water sample.

Market Volatility Transmission and Central Banking: What Happened during the Subprime Crisis?

Kamel Malik Bensafta,Gervasio Semedo 한국국제경제학회 2014 International Economic Journal Vol.28 No.4

We examine market volatility spillover during calm and crisis periods. First, we define endogenous and exogenous market volatility: endogenous volatility refers to the early part of uncertainty in the market, while, exogenous volatility is not fully anticipated and occurs as a result of decisions taken by actors and institutions. Endogenous volatility is captured by the mean of the GARCH-type process. We compare market reaction to central banking for two states: outside the subprime crisis and during the subprime crisis. We evaluate the effectiveness of central banking during the crisis. We used a Multivariate GARCH model with structural breaks in variance. Our main findings confirm the American market's impact on European markets, and changes in cross-market spillover during the crisis. The results show the effect of communications, meeting days and policy decisions of the Fed on world markets.

Hygrothermal effects on the behavior of reinforced-concrete beams strengthened by bonded composite laminate plates

Kamel Antar,Khaled Amara,Samir Benyoucef,Mokhtar Bouazza,Mokhtar Ellali 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.69 No.3

The purpose of this paper is to investigate the hygrothermal effects on the behavior of reinforced-concrete beams strengthened by bonded composite laminate plates (n/90 m)s. This work is based on a simple theoretical model to estimate the interfacial stresses developed between the concrete beam and the composite with taking into account the hygrothermal effect. Fibre orientation angle effects of number of 90° layers and effects of plate thickness and length on the distributions of interfacial stress in the concrete beams reinforced with composite plates have also been studied.

BEPAT: A platform for building energy assessment in energy smart homes and design optimization

Kamel, Ehsan,Memari, Ali M. Techno-Press 2017 Advances in energy research Vol.5 No.4

Energy simulation tools can provide information on the amount of heat transfer through building envelope components, which are considered the main sources of heat loss in buildings. Therefore, it is important to improve the quality of outputs from energy simulation tools and also the process of obtaining them. In this paper, a new Building Energy Performance Assessment Tool (BEPAT) is introduced, which provides users with granular data related to heat transfer through every single wall, window, door, roof, and floor in a building and automatically saves all the related data in text files. This information can be used to identify the envelope components for thermal improvement through energy retrofit or during the design phase. The generated data can also be adopted in the design of energy smart homes, building design tools, and energy retrofit tools as a supplementary dataset. BEPAT is developed by modifying EnergyPlus source code as the energy simulation engine using C++, which only requires Input Data File (IDF) and weather file to perform the energy simulation and automatically provide detailed output. To validate the BEPAT results, a computer model is developed in Revit for use in BEPAT. Validating BEPAT's output with EnergyPlus "advanced output" shows a difference of less than 2% and thus establishing the capability of this tool to facilitate the provision of detailed output on the quantity of heat transfer through walls, fenestrations, roofs, and floors.

Biophysical properties of PPF/HA nanocomposites reinforced with natural bone powder

Kamel, Nagwa A.,Mansour, Samia H.,Abd-El-Messieh, Salwa L.,Khalil, Wafaa A.,Abd-El Nour, Kamal N. Techno-Press 2015 Advances in materials research Vol.4 No.3

Biodegredable and injectable nanocomposites based on polypropylene fumarate (PPF) as unsaturated polyester were prepared. The investigated polyester was crosslinked with three different monomers namely N-vinyl pyrrolidone (NVP), methyl methacrylate (MMA) and a mixture of NVP and MMA (1:1 weight ratio) and was filled with 45 wt% of hydroxyapatite (HA) incorporated with different concentrations of chemically treated natural bone powder (NBP) (5, 10 and 15 wt%) in order to be used in treatment of orthopedics bone diseases and fractures. The nanocomposites immersed in the simulated body fluid (SBF) for 30 days, after the period of immersion in-vitro bioactivity of the nanocomposites was studied through Fourier transform infrared (FTIR), scanning electron microscope (SEM), energy dispersive X-ray (EDX) in addition to dielectric measurements. The degradation time of immersed samples and the change in the pH of the SBF were studied during the period of immersion.