Jelwan J.,Holy Spirit University of Kaslik
Journal of Applied Mechanics and Technical Physics | Year: 2017
This paper re-examines the creep life methodology based on the continuum damage mechanics (CDM) of the Kachanov and Rabotnov theory. Uniaxial creep and multiaxial creep rupture formulations are presented taking into account the primary creep effect. The scalar damage parameter is computed up to time-to-rupture as a function of time and stress. The methodology implemented is based on the uniaxial time-to-rupture obtained experimentally. The times-to-rupture for bars with different notches are calculated. It is demonstrated that the use of the damage parameter is vital to indicate the critical damage location where failure occurs. Results are compared to those obtained experimentally. It is shown that the primary creep inclusion has a significant effect on the damage distribution zone. © 2017, Pleiades Publishing, Ltd.
Bouri E.I.,Holy Spirit University of Kaslik
Economics Bulletin | Year: 2013
This paper examines the conditional volatility and return linkages for the equity markets of Morocco, Tunisia, Egypt, Israel, Lebanon, Jordan, Kuwait, Bahrain, Qatar, UAE, Saudi Arabia, and Oman over the period 2005-2012. To this end, we employ a multivariate model with time varying conditional variances and correlations and with leptokurtic distribution which allows for both return asymmetry and fat tails. Particularly, we investigate the pre- and post-stress periods using the Israeli-Hezbollah war in July 2006 and the global financial crisis of 2008 as dating points for detecting the time varying variance and correlation behaviours across the twelve equity markets. We find strong evidence that a downward trend in return correlations estimates across a number of MENA equity markets is driven equally by both the war and the global financial crisis, implying that there still appear to be benefits from regional portfolio diversification even in stress periods when they are most necessary. Finally, we use the estimated results to compute the optimal weights in order to make the best portfolio allocations.
Bouri E.I.,Holy Spirit University of Kaslik |
Yahchouchi G.,Holy Spirit University of Kaslik
Journal of Economic Studies | Year: 2014
Purpose: This paper aims to examine the dynamic relationship across stock market returns in Morocco, Tunisia, Egypt, Lebanon, Jordan, Kuwait, Bahrain, Qatar, United Arabic Emirates (UAE), Saudi Arabia, and Oman from June 2005 to January 2012. Design/methodology/approach: The paper uses a multivariate model with leptokurtic distribution which allows for both return asymmetry and fat tails. The paper also derives from the model the conditional correlation between stock markets and examines the impact of the global financial crisis of 2008 on the conditional variance and correlation. Findings: The empirical results show that the Middle East and North African (MENA) markets are interconnected by their volatilities and not by their returns. Volatility persists in each market and significant volatility spillovers from small to relatively larger markets. During the crisis, the paper finds that conditional volatilities across markets increase but then during the post-crisis period return to their pre-crisis levels. More importantly, the conditional correlation behaves differently, with a significant evidence of downwards trend in some correlations across the MENA stock markets. Research limitations/implications: One limitation of the study relates to the relatively short-sample period which drives the empirical results. Practical implications: The key results imply that there is still a possibility of benefits from portfolio diversification across specific MENA countries during periods of high volatility. Originality/value: No previous study investigates the transmission of both the first and second moments of the return series across the MENA stock markets allowing for time-varying volatility and correlation and accounts for the 2008 global financial crisis to examine whether the conditional volatilities and correlations have strengthened or weakened during the crisis and afterwards. © Emerald Group Publishing Limited.
Habib B.,Holy Spirit University of Kaslik
2017 13th International Wireless Communications and Mobile Computing Conference, IWCMC 2017 | Year: 2017
This paper aims to present a new architecture for MIMO simulator for radio propagation channels. The architecture works with time-varying 802.15.7 Visible Light Communications (VLC)-LED Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) channels. It is used to test, 'on-table', VLC outdoor automotive crossroad propagation channels with a frequency of 650 THz. The simulator uses impulse responses obtained from ray-tracing modeling for multiple scenarios. Moreover, it uses Rayleigh fading and Kronecker method to vary the channel and converting it to 8x8 MIMO. The digital block architecture of the simulator is designed, analyzed and implemented on Xilinx Virtex-VII XC7VX690T FPGA. The output signals accuracy, FPGA occupation and latency are analyzed. © 2017 IEEE.
Karavetian M.,Maastricht University |
de Vries N.,Maastricht University |
Rizk R.,Holy Spirit University of Kaslik |
Elzein H.,Lebanese National Kidney Registry
Nutrition Reviews | Year: 2014
Strategies to enhance knowledge of and adherence to dietary guidelines for management of hyperphosphatemia in hemodialysis patients have been studied extensively over the past decade. This review is the first to compile all of them (2003-2013) and conduct a meta-analysis through calculation of effect size, with the aim of identifying the optimal nutrition education methods for effective management of hyperphosphatemia in hemodialysis patients. The following strategies were identified as being effective in changing dietary behavior: 1) use of self-evaluation and self-regulation techniques within educational tools, along with easy-to-apply skills; 2) individualized counseling by a renal dietitian provided just before the hemodialysis session; 3) high-intensity education; and 4) long duration of interventions. Future studies should focus on conducting randomized controlled trials with powered samples to help generate stronger evidence. © 2014 International Life Sciences Institute.
De Laat J.,University of Poitiers |
Dao Y.H.,University of Poitiers |
Hamdi El Najjar N.,University of Poitiers |
Daou C.,Holy Spirit University of Kaslik
Water Research | Year: 2011
The decomposition rate of H 2O 2 by iron(III)-nitrilotriacetate complexes (Fe IIINTA) has been investigated over a large range of experimental conditions: 3 < pH < 11, [Fe(III)] T,0: 0.05-1 mM; [NTA] T,0/[Fe(III)] T,0 molar ratios: 1-250; [H 2O 2] 0: 1 mM-4 M) and concentrations of HO radical scavengers: 0-53 mM. Spectrophotometric analyses revealed that reactions of H 2O 2 with Fe IIINTA (1 mM) at neutral pH immediately lead to the formation of intermediates (presumably peroxocomplexes of Fe IIINTA) which absorb light in the region 350-600 nm where Fe IIINTA and H 2O 2 do not absorb. Kinetic experiments showed that the decomposition rates of H 2O 2 were first-order with respect to H 2O 2 and that the apparent first-order rate constants were found to be proportional to the total concentration of Fe IIINTA complexes, were at a maximum at pH 7.95 ± 0.10 and depend on the [NTA] T,0/[Fe(III)] T,0 and [H 2O 2] 0/[Fe(III)] T,0 molar ratios. The addition of increasing concentrations of tert-butanol or sodium bicarbonate significantly decreased the decomposition rate of H 2O 2, suggesting the involvement of HO radicals in the decomposition of H 2O 2. The decomposition of H 2O 2 by Fe IIINTA at neutral pH was accompanied by a production of dioxygen and by the oxidation of NTA. The degradation of the organic ligand during the course of the reaction led to a progressive decomplexation of Fe IIINTA followed by a subsequent precipitation of iron(III) oxyhydroxides and by a significant decrease in the catalytic activity of Fe(III) species for the decomposition of H 2O 2. © 2011 Elsevier Ltd.
Bouri E.,Holy Spirit University of Kaslik
Energy | Year: 2015
This paper examines the return and volatility linkages between oil prices and the Lebanese stock market by applying the newly developed VAR-GARCH (Vector Autoregressive-Generalized Autoregressive Conditional Heteroskedasticity) model to weekly data from 30 January 1998 to 30 May 2014. To better understand the impact of the global financial crisis, we divide the data into three sub-periods: the pre-crisis period (02 February 1998-28 December 2007), the crisis period (02 January 2008-30 June 2009), and the post-crisis period (01 July 2009-30 May 2014). Contrary to previous studies showing the two-way transmission of return and volatility from oil prices to the stock markets of oil-exporting countries, our empirical results for the whole period reveal weak unidirectional return and volatility transmissions from oil prices to the Lebanese stock market. While the interrelationship between oil prices and Lebanese stocks increased during the crisis, it eased significantly in the post-crisis period. Our empirical results are important for policymakers involved in shock prevention and for portfolio managers seeking optimal portfolio allocation. © 2015 Elsevier Ltd.
Bouri E.,Holy Spirit University of Kaslik
Energy Economics | Year: 2015
The role of oil price volatility in predicting the stock-market volatility of small oil-importing countries that have a substantial number of investors from neighboring oil-exporting countries remains unexplored. To refine our basic understanding of this role, this paper proposes a methodological extension of the recently developed causality-in-variance procedure and considers the case of Lebanon and Jordan. These two heavy importers of oil are interesting in the sense that they are located in a region with a large number of rich oil-exporting countries, so their stock markets are tied to oil-exporters by way of foreign investors. The conditional mean and variance of returns are modeled within an ARMAX-GARCH framework that accommodates three salient features of the data, namely: autocorrelation, day-of-the-week effects, and movements in international markets. For comparison purposes, the stock markets of Morocco and Tunisia are also included in the study. Empirical analyses highlight the dynamic effects of the global financial crisis on the volatility spillovers between oil and the stock markets of oil-importing countries and provide more insights into the seemingly contradictory effects of being oil-importers while having investors from oil-exporting countries. The main results indicate that the volatility spillover is much more apparent from the world oil market to the stock market of Jordan than the other way around, whereas oil volatility is not a good predictor of Lebanese stock market volatility. Finally, policy/practical implications and conclusions for future research are drawn. © 2015 Elsevier B.V.
Bouri E.,Holy Spirit University of Kaslik
Energy Policy | Year: 2015
Within the new developed causality-in-variance approach, this paper builds up a broad methodological framework to more accurately capture the risk spillover effects between global oil prices and Jordanian stock market returns during the period 1 March 2003-31 January 2014. The sample period is divided, on the basis of the 2008 financial crisis, into pre-crisis and post-crisis periods. Results for the pre-crisis period show a lack of risk spillovers between global oil and the Jordanian stock market. After the crisis, however, we find evidence for one-way risk spillover running from the oil market. These findings have implications for the design of appropriate asset allocation and regulatory policies to manage risk spillover effects. © 2015 Elsevier Ltd.
Marx F.,Orange Group |
Farah J.,Holy Spirit University of Kaslik
IEEE Vehicular Technology Conference | Year: 2015
In this paper, we present a novel iterative approach for canceling the phase noise generated by imperfect local oscillators in Orthogonal Frequency Division Multiplexing receivers. After the cancellation of Common Phase Error (CPE), an iterative technique is introduced which estimates Inter-Carrier Interference (ICI) components in the frequency domain and cancels their contribution in the time domain. Simulations are conducted in order to investigate the influence of several parameters, such as the modulation scheme, the number of carriers and the phase noise bandwidth on the system's performance. Channel coding is used in conjunction with our iterative algorithm, for the correction of residual errors. Simulation results are presented for the case of AWGN and multi-path fading channels. © 2005 IEEE.