Diab N.A.,Rafik Hariri University |
Lakkis I.A.,American University of Beirut
Journal of Tribology | Year: 2016
This paper presents direct simulation Monte Carlo (DSMC) numerical investigation of the dynamic behavior of a gas film in a microbeam. The microbeam undergoes large amplitude harmonic motion between its equilibrium position and the fixed substrate underneath. Unlike previous work in literature, the beam undergoes large displacements throughout the film gap thickness and the behavior of the gas film along with its impact on the moving microstructure (force exerted by gas on the beam's front and back faces) is discussed. Since the gas film thickness is of the order of few microns (i.e., 0.01 Kn 1), the rarefied gas exists in the noncontinuum regime and, as such, the DSMC method is used to simulate the fluid behavior. The impact of the squeeze film on the beam is investigated over a range of frequencies and velocity amplitudes, corresponding to ranges of dimensionless flow parameters such as the Reynolds, Strouhal, and Mach numbers on the gas film behavior. Moreover, the behavior of compressibility pressure waves as a function of these dimensionless groups is discussed for different simulation case studies. © 2016 by ASME.
Arkadan A.A.,Marquette University |
El Hariri M.,Rafik Hariri University
IEEE Transactions on Magnetics | Year: 2016
An electromagnetic-state space-wavelet neural network modeling environment is presented and used for the characterization of high-speed synchronous generators during out-of-phase operation in distributed generation (DG) of a microgrid. This mode of operation may result in stresses in the network or the failure of the high-speed generators. The approach is validated, by comparing simulation results with test data, and its effectiveness is established in terms of accuracy and fast response. In addition, it is demonstrated in a case study involving two DG units in a microgrid that the stresses and damages are minimized in an out-of-phase DG unit when connected to the grid through an inverter. © 1965-2012 IEEE.
Issa I.,Rafik Hariri University |
Moucari R.,Advanced Cure Diagnostic Center
World Journal of Gastroenterology | Year: 2014
Probiotics use has increased tremendously over the past ten years. This was coupled with a surge of data relating their importance in clinical practice. Antibioticassociated diarrhea, whose frequency has risen recently, was one of the earliest targets with data published more than ten years ago. Unfortunately, available trials suffer from severe discrepancies associated with variability and heterogeneity of several factors. Most published randomized controlled trials and subsequent meta-analyses suggest benefit for probiotics in the prevention of antibiotic-associated diarrhea. The same seems to also apply when the data is examined for Clostridium difficile -associated colitis. However, the largest randomized double-blind placebo-controlled trial to date examining the use of a certain preparation of probiotics in antibiot-ic-associated diarrhea showed disappointing results, but it was flawed with several drawbacks. The commonest species of probiotics studied across most trials is Lactobacillus ; however, other types have also shown similar benefit. Probiotics have enjoyed an impeccable safety reputation. Despite a few reports of severe infections sometimes leading to septicemia, most of the available trials confirm their harmless behavior and show similar adverse events compared to placebo. Since a consensus dictating its use is still lacking, it would be advisable at this point to suggest prophylactic use of probiotics to certain patients at risk for antibiotic-associated diarrhea or to those who suffered previous episodes. © 2014 Baishideng Publishing Group Inc. All rights reserved.
Hammoud J.,Rafik Hariri University
Mediterranean Gas and Oil International Conference, MedGO 2015 - Conference Proceedings | Year: 2015
The Levantine basin has recently become the new frontier for oil and gas discoveries. In spite of the uncertainty surrounding the volumes and the commerciality of existing reserves, the Lebanese State has already undertaken initial steps, toward transformation into a back gold economy. Luckily enough, Lebanon does not have to reinvent the wheel in the area of oil and gas management. Accordingly, this paper poses and attempts to answer the following research question: what lessons can Lebanon learn from the experiences of other nations and petroleum corporations that could be integrated and adapted, to form a jumpstarting body of knowledge, conducive toward the formulation of effective national petroleum management strategy and policy? The paper will employ a mix of sectoral analysis of the international petroleum industry, and comparative analysis of a select number of oil and gas producing nations' experiences. In particular, the paper will address the main governance aspects of national petroleum management. © 2015 IEEE.
Issa I.A.,Rafik Hariri University |
Soubra O.,Beirut Arab University |
Nakkash H.,Beirut Arab University |
Soubra L.,Beirut Arab University
Digestive Diseases and Sciences | Year: 2012
Background Stress ulcer prophylaxis (SUP) is commonly used in hospitals. Although its indications are better delineated for intensive care unit (ICU) patients, its use in non-ICU settings is somewhat arbitrary and based on judgment. Objective We attempted to assess the extent of SUP overuse in our hospital. We also carefully collected and analyzed several variables to detect associations governing this flawed behavior and its financial burden on the hospital's budget. Materials and Methods We retrospectively analyzed charts of patients admitted to the medical floor of a tertiary referral university hospital over a 1 year period. All adult patients admitted to the medical ward who received at least one dose of SUP were included and reviewed for a multitude of variables in addition to the appropriateness of acid suppression therapy (AST). Results We included 320 charts and found that 92% of patients admitted during that period were not eligible for SUP. The total inappropriateness of SUP was noted to be 58% (p = 0.015). Increasing age and male gender were found to be significant variables in AST misuse (p = 0.045 and p = 0.010), much like duration of hospital stay (p = 0.008). Comorbidities was also found to be a defining variable for AST overuse (odds ratio [OR] = 3.27). Patients with two or more minor risk factors were also subjected more to SUP inappropriately (OR = 3.53), in addition to patients of certain specialties (Neurology, Infectious Diseases, etc.). Our calculated financial burden was more than $23,000 per year for the medical floor. Conclusion This retrospective study confirmed the growing suspicion that SUP misuse is evident on the medical floors. We also delineated several factors and variables associated with and affecting SUP overuse. © 2012 Springer Science+Business Media, LLC.