Khaled Chahine

On Variants of the Frequency Power Law for the Electromagnetic Characterization of Hydraulic Concrete

The objective of this paper is threefold: First, dielectric permittivity measurements on concrete specimens are compared among the different variants of Jonschers model. Each of these variants considers just a limited number of parameters (two or three), based on certain material-dependent and/or bandwidth-related simplifying assumptions. According to this setup, these variants affect the inherent “universality” of the model by imposing a tradeoff between representativeness and practicality. Such an effect becomes more pronounced for concrete mixtures with high moisture content. Next, we propose a computationally efficient two-step procedure for estimating the four model parameters; this procedure filters the linear parameters that contribute to model deviation from the frequency power law by applying the Kramers-Krönig relations. Only two parameters therefore need to be estimated numerically, whereas the filtered parameters can be estimated in closed form as the solution to a simple linear least-squares problem. All of these variants are applied to an array of concrete mixtures and then evaluated by their goodness of fit. The results obtained demonstrate that accounting for all model parameters via the proposed procedure yields the smallest fitting error, thus enhancing the data interpretation stage. Moreover, a parametric study has been carried out in order to correlate the dispersion parameter n present in each variant of Jonschers model with the physical and hydric characteristics of the concrete mixtures. This procedure has made it possible to derive trends providing information on the conditioning state of the studied media.

Interpolation-based matrix pencil method for parameter estimation of dispersive media in civil engineering

In this paper, we propose a modified matrix pencil method for the problem of time delay estimation in dispersive media obeying a particular frequency power law, namely, the constant-Q model. Being based on a Vandermonde decomposition of the prediction matrix, the matrix pencil method produces biased estimates when applied directly to data of the constant-Q model. The proposed approach allows to compensate for the bias inherent to the classical method by restoring the Vandermonde structure via a spline-interpolation technique. The restoration involves an iterative procedure where each iteration selects a set of interpolated samples depending on the value of the quality factor of the previous iteration. The algorithm is tested on simulated data representing radar acquisitions over a stratified dispersive medium, and its performance is assessed against the Cramer-Rao lower bound.

Design and analysis of an HVAC-based heat recovery system

In this paper, the design of a heat recovery system is presented and analyzed. It allows recovering the heat waste from Heating, Ventilating, and Air Conditioning (HVAC) systems to obtain hot water. A code is developed for this purpose, which allows simulating the heat transfer in the system. The outlet temperature is studied in terms of the water flow rate and the amount of ton refrigerant in the system. It is shown that the water can be heated up to 347 K with a HVAC system of 9 tons of refrigerant (108 000 Btu/hr).

Parameter Estimation of Damped Power-Law Phase Signals via a Recursive and Alternately Projected Matrix Pencil Method

We propose a novel algorithm based on the matrix pencil method to estimate the parameters of a class of signals modeled as damped power-law phase signals. This class arises primarily from the electromagnetic probing of dispersive geological and civil engineering materials as a consequence of the universal dielectric response. When stratified media are considered, direct application of conventional matrix-shifting methods is hindered not only by the nonlinear frequency dependency which destroys the desired shift-invariance property of the data matrix, but also by the stratified structure of the medium which introduces a cumulative effect. In this regard, the proposed algorithm restores recursively the Vandermonde structure of one mode vector at a time by means of a spline-interpolation technique and then orthogonally projects it to filter out its contribution before passing to another. The algorithm is tested on simulated and experimental data resulting from the probing of a stratified dispersive medium, and its performance is assessed against the Cramér-Rao lower bound. For the example of experimental data, collected from concrete cores by means of a cylindrical transition line, the permittivities at the reference frequency and the dispersion indices are determined using the new algorithm and compared with those of a nonlinear optimization scheme.

Smart traffic light control system

Traffic light control systems are widely used to monitor and control the flow of automobiles through the junction of many roads. They aim to realize smooth motion of cars in the transportation routes. However, the synchronization of multiple traffic light systems at adjacent intersections is a complicated problem given the various parameters involved. Conventional systems do not handle variable flows approaching the junctions. In addition, the mutual interference between adjacent traffic light systems, the disparity of cars flow with time, the accidents, the passage of emergency vehicles, and the pedestrian crossing are not implemented in the existing traffic system. This leads to traffic jam and congestion. We propose a system based on PIC microcontroller that evaluates the traffic density using IR sensors and accomplishes dynamic timing slots with different levels. Moreover, a portable controller device is designed to solve the problem of emergency vehicles stuck in the overcrowded roads.

Heating water using the recovered chimney waste heat - Prototype and experimental analysis

This work discusses a waste heat recovery system applied to chimneys allowing to heat water in residential buildings. A prototype illustrating the idea is implemented and tested. Different waste heat scenarios by varying the quantity of burned firewood (heat input) are experimented. Temperature measurements are performed at different parts of the heat recovery system. Gas flow rates of the Exhaust pipes of the system are also measured. Using this system, measurements showed that a tank of 95 L of water can be heated up to 78 °C within one hour. Obtained results show that the convection and radiation exchanges at the bottom surface of the tank have a considerable impact on the total heat transfer rate of the water (up to 70%) used in the prototype under test.

On the variants of Jonscher's model for the electromagnetic characterization of concrete

The objective of this paper is twofold. Firstly, we carry out a comparison on measurements of the dielectric permittivity of concrete among the different variants of Jonschers model found in the literature. Each of these variants considers only a limited number of parameters (two or three) based on certain material-dependent and/or bandwidth-related simplifying assumptions. Hence, they affect the inherent “universality“ of the model by imposing a tradeoff between representability and practicability. This effect becomes more pronounced for concrete mixtures with high moisture content. Secondly, we propose a computationally efficient, two-step procedure for the estimation of the four model parameters. The proposed procedure filters the linear parameters that contribute to the deviation of the model from the frequency power law by employing the Kramers-Krönig relations. Therefore, only two parameters need to be estimated numerically, whereas the filtered parameters are estimated in closed form as the solution of a simple linear least-squares problem. All the variants are applied to various concrete mixtures and evaluated by their goodness of fit. The obtained results show that accounting for the whole parameters of the model via the proposed procedure provides the lowest fitting error, and thus enhances the interpretation of data.

Multi control chandelier operations using XBee for home automation

Home automation systems aim to control all home activities and functionalities. Control can be done through a remote control that sends command signals wirelessly by means of infrared radiation, Bluetooth connectivity, or any other RF technology as well as via internet or GSM communication. The controlled target devices usually include domestic appliances, security and safety systems, HVAC systems, home theater, lights, and many other home tasks. In this study, we design, program, and implement a light chandelier with multiple functionalities. The operational modalities comprise manual and remote on/off, different working timers, daylight, romance option, light dimming, party style, on/off luminosity turning, password keys, and motion detection. The chandelier remote control uses XBee transceivers that fulfill secure commands and prevent any interference between similar systems. The remote control realization is based on PIC 16F877A microcontroller and supported by an LCD to display notifications.

Lebanon's qualifications to upgrade for a smarter grid

The main objectives of the Smart Grid is to ensure a more resilient infrastructure, reliable power delivery, reduced carbon footprint, protection against technical and non-technical losses, and elevate customer satisfaction. This is achieved through the implementing of new technologies such as Distributed Energy Resources, Smart Metering, Bi-Directional Power Flow, Demand Side Management, Distributed Automation, and Geographic Information System. When examining the energy sector at Lebanon, its clear that Lebanon has either fully deployed, or is in the process of deployment, or has the prerequisite of each of the aforementioned technologies. This paper emphasis on Lebanons qualifications toward a smarter grid, it will be shown that Lebanon has a utilities Geographic Information System customized all over the Lebanese territories and by the end of 2016, Lebanons analogue electromechanical meters will be replaced by smart meters. Moreover, the National Energy Efficiency Action Plan for Lebanon 2011-2015 (NEEAP) published by the Ministry of Energy and Water with its 14 initiatives consists of promoting renewable products to constructing and upgrading Hydro plants. Wind and solar farms shall pave the way for a larger energy mix and a higher generation capacity. The following study proves that Lebanon has the potentials to fully upgrade toward a smarter grid.

ERSS-RLNC

Random Linear Network Coding (RLNC) is a promising technology of Network Coding (NC) that has been proved to be both sufficient and efficient. To enable the deployment of RLNC in real networks, this paper first introduces a new efficient and flexible authentication-encryption scheme that is immune to Byzantine and eavesdropping attacks. The proposed scheme achieves simultaneously information confidentiality, packet integrity and source authentication with minimum computational complexity and memory consumption. It also presents a new technique for constructing an integer Global Encoding Matrix (GEM) that satisfies the inversion property in a dynamic manner. In addition, the proposed scheme uses dynamic keys to ensure robustness against attacks. Secondly, an efficient implementation of Binary RLNC, suitable for battery constrained mobile devices with low computational capabilities such as mobile phones and sensors, is defined. The effectiveness of the coding process is proved by modifying the Galois field of calculation from integer (int8, int16) to binary. Not only does this ensure low computational requirements, high throughput and low energy consumption, but also reduces the statistical characteristics of the coding process. The obtained theoretical and experimental results show that the new scheme is secure and efficient compared with many recent works in this field.