Numerical study of an individual Taylor bubble rising through stagnant liquids under laminar flow regime

Slug flow is one of the main flow regimes encountered in multiphase flow systems especially in oil and gas production systems. In the present study, the rise of single Taylor bubble through vertical stagnant Newtonian liquid is investigated by performing complete dimensionless treatment followed by an order of magnitude analysis of the terms of equations of motion. Based on this analysis, it is concluded that Froude, E€otv€os and Reynolds numbers are the sole physical parameters influencing the dimensionless slug flow equations. Using the guidelines of the order of magnitude analysis, computational fluid dynamics simulation is carried out to investigate the dynamics of Taylor bubbles in vertical pipe using the volume-of-fluid (VOF) method. Good agreement with previous experimental data and models available in the literature is established confirming that the density ratio, viscosity ratio and the initial ratio of bubble size to pipe diameter ðLTB=DÞ have minimal effect on the main hydrodynamic features of slug flow. Based on the developed results, correlations for the terminal velocity of the Taylor bubble and the dimensionless wall shear stress are proposed showing the significance of these main dimensionless parameters and support other important theoretical and experimental work available in the literature

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

A fuzzy approach to the generation expansion planning problem in a multi-objective environment

In many power system problems, the use of optimization techniques has proved inductive to reducing the costs and losses of the system. A fuzzy multi-objective decision is used for solving power system problems. One of the most important issues in the field of power system engineering is the generation expansion planning problem. In this paper, we use the concepts of membership functions to define a fuzzy decision model for generating an optimal solution for this problem. Solutions obtained by the fuzzy decision theory are always efficient and constitute the best compromise.

A modified segmentation method for determination of IV vessel boundaries

Coronary heart diseases are ranked as the top diseases causing death in many countries worldwide. Intravascular Ultrasound (IVUS) directly images the vessel from inside and allows the extraction of vessel bounders and the measurement of vessel cross-sectional area. This paper introduces an approach for detection of lumen and media-adventitia borders in an Intravascular (IV) image. In the proposed method, a modified fast algorithm is applied to determine the lumen and media-adventitia contours. The modified fast algorithm is fully tested and it showed an improvement in speed of up to 200% while preserving an accuracy rate of 98%. Keywords: Intravascular, Contour segmentation, Fast search, 3D reconstructio

Automated new license plate recognition in Egypt

License plate recognition (LPR) was an effective form of Automatic Vehicle Identification (AVI) systems. In this paper, a new and simple technique was presented for Egyptian vehicle’s LPR system. The proposed technique consists of three major parts: Extraction of plate region, recognition of plate characters, and database communication. A video stream was one of the most important advantages of this system. The real-time was capability, and that it did not require any additional sensor input such as infrared sensors. This approach provided a good direction and performance for Automated New License Plate Recognition in Egypt

Environmental Impacts of Reconstruction Activities: A Case of Lebanon

Significant damages incurred across Lebanon during the July 2006 war encompassing the destruction of road networks, bridges and overpasses as well as a vast number of dwelling units. It is anticipated that reconstruction works after the war shall unavoidably create a newly founded demand for natural resources, most notably primary and secondary construction material. This paper assesses the war-related impacts of the construction sector on the environment coupled with recommendations for controlling and mitigating these impacts. A cost benefit analysis of four different scenarios for supplying construction material was conducted based on their environmental and fiscal costs as well as their economic benefits and government returns. The Fixed Box Model was applied to estimate air pollutants concentration. Results indicated that the preferred alternative for the supply of cement primarily consists of local manufacturing of 100 percent of the required quantities. With regards to sand and aggregates, the analysis indicated that the preferred alternatives are to either rely on local production or import 25 percent of the required material. The predicted average concentration of Total Suspended Particulates at the southern suburb of Beirut site exceeded the recommended values of the Lebanese, EU, USEPA, and WHO standards

Assessment of public vs. private MSW management: a case study

Public–private partnerships in urban environmental services have witnessed increased interest in recent years primarily to reform the weak performance of the public sector, reduce cost, improve efficiency, and ensure environmental protection. In this context, successful public–private partnerships require a thorough analysis of opportunities, a deliberate attention to process details, and a continuous examination of services to determine whether they are more effectively performed by the private sector. A comparative assessment of municipal solid waste collection services in the two largest cities in Lebanon where until recently municipal solid waste collection is private in one and public in the other is conducted. While quality of municipal solid waste collection improved, due to private sector participation, the corresponding cost did not, due to monopoly and an inadequate organizational plan defining a proper division of responsibilities between the private and the public secto

Land use impact on the spatial and seasonal variation of contaminant loads to Abou Ali river and its coastal zone in North Lebanon

Assessment of contaminant loads to surface water bodies is important for the proper use and management of these water resources. Many pollution assessment studies have focused on heavily polluted rivers of industrialized countries as well as major rivers in other less developed countries. Studies concerning relatively small rivers in developing countries are rather limited although water quality in such rivers may be impacted by human activity and land use patterns resulting inconsiderable ecological changes. This study assesses the land use impact on water quality in the Abou Ali River Basin and its coastal zone in North Lebanon, based on multiple indicators, primarily concentrations of nutrients, metals and pesticides. The assessment was conducted during the dry season in 2002 and wet season in 2003. The water quality of the Abou Ali River is not significantly degraded (as generally perceived) and exhibits slight seasonal differences in the interaction between land use and water quality. The worst water quality is apparent in the Tripoliarea where the total pollution of the upstream flow accumulates exacerbated by local wastewater discharge. The steep profile of the Abou Ali River flushes contaminants towards the estuary and the sea. Future work requires the development of the approach that assists in evaluating current and future environmental conditions at a river/estuary/sea interface within a rigorous framewor

A Modular Multilevel Voltage-Boosting Marx Pulse-Waveform Generator for Electroporation Applications

In order to overcome the limitations of the existing classical and solid-state Marx pulse generators, this paper proposes a new modular multilevel voltage-boosting Marx pulse generator (BMPG). The proposed BMPG has hardware features that allow modularity, redundancy, and scalability as well as operational features that alleviate the need of series-connected switches and allows generation of a wide range of pulse waveforms. In the BMPG, a controllable, low-voltage input boost converter supplies, via directing/blocking (D/B) diodes, two arms of a series modular multilevel converter half-bridge sub-modules (HB-SMs). At start up, all the arm's SM capacitors are resonantly charged in parallel from 0 V, simultaneously via directing diodes, to a voltage in excess of the source voltage. After the first pulse delivery, the energy of the SM capacitors decreases due to the generated pulse. Then, for continuous operation without fully discharging the SM capacitors or having a large voltage droop as in the available Marx generators, the SM capacitors are continuously recharged in parallel, to the desired boosted voltage level. Because all SMs are parallelly connected, the boost converter duty ratio is controlled by a single voltage measurement at the output terminals of the boost converter. Due to the proposed SMs structure and the utilization of D/B diodes, each SM capacitor is effectively controlled individually without requiring a voltage sensor across each SM capacitor. Generation of the commonly used pulse waveforms in electroporation applications is possible, while assuring balanced capacitors, hence SM voltages. The proposed BMPG has several topological variations such as utilizing a buck-boost converter at the input stage and replacing the HB-SM with full-bridge SMs. The proposed BMPG topology is assessed by simulation and scaled-down proof-of-concept experimentation to explore its viability for electroporation applications. - 1986-2012 IEEE.Manuscript received June 12, 2018; revised October 23, 2018 and December 29, 2018; accepted February 5, 2019. Date of publication February 18, 2019; date of current version August 29, 2019. This work was supported by the Qatar National Research Fund (a member of the Qatar Foundation) under NPRP Grant 7-203-2-097. Recommended for publication by Associate Editor J. Clare. (Corresponding author: Mohamed A. Elgenedy.) M. A. Elgenedy is with the Department of Electronic and Electrical Engineering, University of Strathclyde, Glasgow G1 1RD, U.K., and also with the Department of Electrical Engineering, Faculty of Engineering, Alexandria University, Alexandria 21544, Egypt (e-mail:,[email protected]).Scopu

Public perception and economic implications of bottled water consumption in underprivileged urban areas

This paper presents a comparative assessment of public perception of drinking water quality in two underprivileged urban areas in Lebanon and Jordan with nearly similar cultural and demographic characteristics. It compares the quality of bottled water to the quality of the drinking water supplied through the public network and examines the economic implications of bottled water consumption in the two study areas. Participants' perception of the quality of drinking water provided via the public network was generally negative, and bottled water was perceived to be of better quality in both areas, thus affecting drinkingwater preferences and consumption patterns. The results reveal that the quality of bottled water is questionable in areas that lack enforcement of water quality standards, thus adding to the burden of an already disadvantaged community. Both areas demonstrated a considerable cost incurred for purchasing bottled water in low income communities reaching up to 26 % of total income