Life Cycle Assessment for Fiber-Reinforced Polymer (FRP)nComposites Used in Concrete Beams: A State-of-the-Art Review

Fiber-reinforced polymer (FRP) composites have become popularly utilized in structural engineering applications. The common use of the FRP composites is related to their economic benefits that can be observed right away or in a long-time period. With increasing concern about global warming and the shortage of natural resources, it is essential to study the environmental implications of the use of FRP composites. Life cycle assessment (LCA) is one of the most common techniques that can be used to take the environmental impact of the FRP into consideration. This paper presents a literature review about the LCA of FRP composites in concrete beams. The LCA results reported in the literature confirmed the use of FRP composites for reinforcing the RC beams instead of conventional steel rebars or that the strengthening of RC beams instead of demolishing and reconstruction is a more environment-friendly approach

Positional control of rotary servo cart system using generalized dynamic inversion

This paper presents the design approach of Generalized Dynamic Inversion (GDI) for angular position control of SRV02 rotary servo base system. In GDI, linear first order constraint differential equations are formulated based on the deviation function of angular position and its rate, and its inverse is calculated using Moore-Penrose Generalized Inverse to realize the control law. The singularity problem related to generalized inversion is solved by the inclusion of dynamic scaling factor that will guarantee the boundedness of the elements of the inverted matrix and stable tracking performance. Numerical simulations and real-time experiment are performed to evaluate the tracking performance and robustness capabilities of the proposed control law considering nominal and perturbed model dynamics. For comparative analysis, the results of GDI is compared with conventional PID control. Simulation and experimental results demonstrate better angular position tracking for the square-wave and sinusoidal waveforms, which reveals the superiority, and agility of GDI control over conventional PID

Hot Spots for Poly Aromatic Hydrocarbons (PAHs) in Sediments and Benthic Organisms in the Coastal Water of Qatar

The state of Qatar has a strategic location within the heart of the Arabian Gulf, the richest oil area in the world. Its extensive coastline (700 km) is experiencing some of the most radical environmental conditions in the world's oceans including extreme temperature, high UV irradiance as well as high evaporations. These extreme conditions are pushing many marine biota to function close to their physiological limits. On the top of the extreme natural hydrographic conditions, there are tremendous stress exerted by oil exploration, production and transportation and probably any remnants from the largest oil spills in history, during the Gulf war in 1991. The present study is the first comprehensive study in the Gulf that is designed to assess the spatial and temporal variability of levels of Poly Aromatic Hydrocarbons (PAHs) in sediments of the Qatari coastal water and their bioaccumulation by dominant benthic invertebrates. Sediments and dominants benthic organisms samples were collected seasonally from thirteen locations in the coastal water of Qatar starting in the winter of 2014 and for four consequent seasons. Ten abundant benthic invertebrate species representing different trophic levels were selected to assess the spatial and temporal variability of PAHs in the Qatar costal water. These species have limited or no mobility, a major criteria for selecting benthic organisms in bio-monitoring programs. These species included gastropods, bivalves, and crustaceans with different trophic positions including carnivores, omnivores, herbivores and detritivores. Samples were analyzed for 16 parent PAHs including low molecular weight parent PAHs (LPAHS) and high molecular weight parent PAHs (HPAHs), 18 alkyl homologs and dibenzothiophenes. The results of the present study will be used for ecological risks assessment. Levels of PAHs in sediments and tissue residues are found to be significantly variable with species, locations, seasons and also with distance from shore (P < 0.05). PAHs concentrations in sediments is negatively correlated with the water temperature (r = ? 0.65) indicating the impact of temperature and probably levels of UV radiations on the fate of PAHs. Levels of PAHs in sediments indicated the presence of few moderately contaminated sites near point sources. Concentrations of PAHs in sediments showed wide spatial and temporal range (5 8.5%) presenting a range of trophic levels including carnivores and filter feeders. Significant correlations (P < 0.05) were found between PAHs tissue residues concentrations and signatures of carbon and nitrogen stable isotopes emphasizing the roles of trophic pathways on the uptake and bioaccumulation levels of individual PAHs in marine invertebrates. The present results are to be supported by more samples from two more seasons. The knowledge from this study intended to assist PAHs monitoring and identification of potential sources to guide management decisions. The outcome of the study is expected to help the regulatory agency (Qatar Ministry of Environment) as well as Gulf organizations such as ROPME to improve environmental laws and set standards based on these studies.qscienc

Observations of hydrographic properties, dissolved oxygen (DO) and chlorophyll-A (Chl-a) (phytoplankton biomass) within the exclusive economic zone (EEZ) of Qatar (central Arabian Gulf)

In situ observations of physical, chemical, and biological parameters of the Qatari water column were conducted to understand the temporal (seasonal) and spatial (regional) variability in the vertical and horizontal distribution of oceanographic properties within the exclusive economic zone (EEZ) of Qatar. Samples were collected from 5 different offshore shallow and deep stations covering the northern and eastern marine regions of the Qatar EEZ during two seasons: late summer (September 2014) and winter (January 2015). Eighteen (18) water samples were analyzed for temperature, salinity, density, dissolved oxygen concentration, dissolved oxygen saturation (DO%), and chlorophyll-a concentration (Chl-a). These data reveal several interesting and unique features that are related to surface warming that give rise to a large excess of evaporation over precipitation, resulting in the formation of several high salinity water masses. The deep offshore EEZ of Qatar was characterized by stratification (seasonal thermocline and pycnocline) during summer when deep water temperature was about 23.5°C (colder than the surface 32.6°C) where reduced stratification appeared to dominate in winter. Well-oxygenated water exists within the surface layer (0-23 m) during both summer and winter. Oxygen saturation layer (concentration 4.53 ml/l; saturation 94.49%) in the deep water extends to bottom (63 m) in winter however oxygen level falls below the summer thermocline (1.35 ml/l corresponding to 28.95% saturation) at Station 5 (63 m depth). Chl-a concentration was high in summer due to high primary productivity but remained sustained at moderate levels in winter. The procedures and methods were carefully applied to ensure the accuracy of the study results. In-situ measurements have high reliability in detecting hydrographic properties; however, it is costly, time consuming, requires ship time and as well as large number of scientific personnel and resources.qscienc

Ashghal Quality Assurance & Quality Control system - QSD Role in Monitoring & Reporting the Quality Performance in Ashghal Projects

Ashghal has established a robust system of quality control and quality assurance for all projects constructed by Ashghal. Ashghal Departments are supervising a sophisticated system of quality control and quality assurance processes and procedures, implemented by the Consultants, Contractors, and Key Supply Chain Partners of Ashghal projects (e.g., Sub-Contractors, Key Suppliers, and Independent Laboratories). This paper illustrates how Ashghal Quality & Safety Department (QSD) monitors and reports the quality performance in Ashghal constructed projects to ensure continuous improvement and adherence to Ashghal quality strategy, policy mission, and targets. QSD is operating as Third Party, reporting directly to Ashghal President, and is monitoring and reporting the compliance of the industry to the quality requirements defined in Qatar Construction Specifications (QCS, 2014), Contracts, Professional Services Agreements, ISO 9001:2015 Standard and specific Ashghal requirements. Effective root cause analysis carried out by the auditing team has led to value-adding activities. QSD has established specific Key Performance Indicators (KPIs) for the management of non-conformities and corrective actions, to improve the performance and minimize the deviations and failures of compliance. QSD is conducting focused and system audits at Ashghal projects and the supply chain and is liaising with departments and individual projects as necessary, to agree on Lessons Learned and Actions to improve the quality of works. These activities include the establishment of consistent criteria of the qualifications and experience of the quality staff of Ashghal departments and Consultants' teams. QSD is making quarterly presentations to the Ashghal President regarding the performance of the Departments (including Contractors' and Consultants' performance) and of the Ashghal Project Managers. The established criteria and evaluation related to the quality are dynamic and reviewed/updated periodically to ensure the improvement of the Quality Performance of Ashghal Projects

First Impact Assessment of Genotoxic Components in the Qatari Marine Environment

The Arabian Gulf is a semi-enclosed sea with very high evaporation and low discharge rates resulting in extreme saline and thermal conditions. Additionally the system is characterized by a weak hydrodynamic flushing resulting in pollutant build-up over time. As a result, compared to open marine systems, added stress imposed by pollutants is likely to have severe consequences. Qatar has witnessed a rapid expansion in coastal development, linked to its industrial and population growth in recent decades. While economically and socially valuable, the growth comes with an associated environmental cost and Qatar's marine environment now faces many pressures including eutrophication, inputs of domestic sewage, discharge of industrial waste and the resuspension of sediment due to coastal construction. Although the threats pose to biota inhabiting Qatar's marine environment are evident, their extent has yet to be fully assessed. A large percentage of contaminants in the aquatic environment consist of potentially (directly or indirectly) genotoxic, carcinogenic and mutagenic substances. A genotoxin can modify the genetic material at non lethal and non cytotoxic concentrations and has often belated effects which are significantly important at the population and community levels. Genotoxins have particularly high ecotoxicological relevance in situations of chronic exposure to low doses and to multiple contaminants (e.g. in case of PAHs rich tarballs arriving in the shorelines), raising he need to establish genotoxicological profiles of the ecosystems. Indeed several regulatory developments such as: EU - Marine Strategy Framework Directive, the or US - Environmental Protection Agency - Integrated Risk Information System have stressed explicitly on the need of the detection and assessment of potential carcinogenic and mutagenic toxicants using genotoxicity endpoints. The analysis of cytogenetic endpoints in organisms exposed to contaminants in their natural environment contributes significantly to the early detection of genotoxic damage. The relevance of cytogenetic parameters and atypical cytogenetic features, such as numerical chromosomal abnormalities, i.e. aneuploidy, have largely proven their relevance as alerting indicators of poor environmental health and relevant biomarkers for the early detection of environmental stressors. The use of marine invertebrates for in situ environmental assessment is a widely accepted method for identifying risks to the ecosystems. Moreover, at the DNA and chromosome levels they express qualitatively similar types of induced damage to that found in higher organism (e.g. numerical and structural chromosomal aberrations). In this study, we aimed to take a step towards Qatar's marine sustainability by assessing the health status of the marine environment, and providing early alerting symptoms of degradation, by having as specific objectives: i) to measure the levels, in abiotic (water, sediments) and a marine invertebrate model species, of various anthropogenic contaminants (metals, polycyclic aromatic hydrocarbons, (PAHs) and Total polyaromatic hydrocarbons (TPH) at 3 selected sites around the Qatari coast, ii) measure the biological response at the chromosome level, and iii) determine the main drivers of genotoxicity through a multivariate analysis in order to establish a first partial genotoxicological profile of the Qatar Marine Zone. The 3 selected sampling sites, with expected different levels and sources of pollution were: South of Al Khor, Al Wakra harbor and South of Doha harbor. Two sampling campaigns were performed, one in summer and one in winter, to evaluate the role of the abiotic parameters, among others, on the bioavailability of the studied contaminants. The native pearl oyster Pinctada radiata was selected as model and surrogate species due to, its wide distribution along the Qatari coast, filter feeder and sessile mode of life and to its ability as a bivalve to bioaccumulate pollutants. Chemical analyses of the main trace metals and hydrocarbons were performed in water, sediment and P. radiata samples. The evaluation of the aneuploidy levels in P. radiata was estimated in 25-30 animals from each sampling site and season, by counting the total number of aneuploid metaphases over 30 metaphases counted per individual. The evaluation of the aneuploidy level on Pinctada radiata from the three sampling sites revealed an occurrence of significantly higher levels in Al-Wakra harbor (17% in summer and 20% in winter) and South of Doha harbor (19% in summer and 17% in winter), when compared to Al Khor (5% in summer cand 7% in winter). No statistically significant differences were observed between seasons in each location. In order to investigate the discrepancy between sampling sites and seasons with respect to all estimated descriptors and to evaluate the relationship between all the studied parameters, a principal component analysis (PCA) was performed. Aneuploidy levels were highly correlated to mercury and PAHs levels in the bivalve tissue. Moreover, the higher aneuploidy levels registered at Al Wakra harbor (both seasons) and Doha harbor (summer) showed a high correlation with the contaminants levels in P. radiata tissues. South of Al Khor (in both sampling seasons) was highly positively correlated with Cadmium (Cd), although this contamination was not responsible for a significant increase of the aneuploidy levels. The studied genotoxic contaminants were found to be highly variable among considered locations and between sampling seasons. Indeed, the 6 observations (contaminants levels among three sampling sites at two sampling seasons) differ substantially, no site or sampling season grouping being observed, which suggests an important spatial and temporal variability of the bioaccumulation of pollutants into P. radiata tissues. The aneuploidy levels, however, were consistently different among sampled locations, but did not differ between the two sampling seasons, suggesting that aneuploidy is the consequence of a local chronic contamination, and not a direct response to the temporal variability of the contaminants in P. radiata tissues. The results of this study confirm the suitability of the cytogenetic endpoints to discriminate, categorize the studied sites as regards to their level of contamination, underlining the added value of the detection of the genotoxicity levels in the marine environment to environmental health assessment and mitigation research programs. Further studies should be developed, under the specific hydrological and toxicological conditions of the Qatar Marine Zone (QMZ), to better explain the underlining mechanisms of such genotoxicity in the local filter feeders. The establishment of a Genotoxicological profile of the QMZ would be a valuable contribution to a wider approach on environmental diagnosis or prognosis, contributing to the protection and sustainability of the QMZ natural habitats and resources.qscienc

Enhancing Physical Layer Secrecy Performance for RIS-assisted RF-FSO Mixed Wireless System

Peer reviewedPublisher PD

Memokath for treating ureteric stricture post cryoablation of renal mass: a case report of rare complication and proposed alternative management

The use of cryoablation in the management of small renal masses is widely acceptable. Although rare but ureteral injury during the procedure with subsequent stricture formation can result in devastating effects on renal function. On the other hand, the management of such strictures requires reconstructive surgery as gold standard. Unfortunately, in some cases the reconstructive surgery might not be feasible, and the treatment usually is ureteral stent insertion that need to be changed regularly. Here we present a case of a 53-year-old gentleman who developed an upper ureteric iatrogenic stricture post cryoablation in which the reconstructive surgery was not feasible due to high procedural risk. We used metallic ureteral stent (Memokath) instead of regular ureteral double J stent. We found that if the reconstructive surgery is not possible the usage of Memokath in treating iatrogenic ureteral strictures is associated with better quality of life, lower costs and a similar functional outcome when compared to ureteral double J stent that needs regular frequent changes

Observed variability in physical and biogeochemical parameters in the central Arabian Gulf

In situ measurements of physical and biogeochemical variables were conducted along a transect in the Exclusive Economic Zone (EEZ) of Qatar during late summer (September 2014) and winter (January 2015) to investigate their vertical, spatial and temporal variability. The study reveals that the water column is characterized by strong stratification during late summer in the deepest station, where the water depth is around 65 m and the surface to bottom temperature variation is around 9.1°C. The water column is vertically homogeneous during winter due to surface cooling and wind mixing. The surface to 23 m water column is characterized by ample dissolved oxygen (DO) during late summer and winter in the offshore regions, however, relatively low DO is found during late summer due to weak mixing and advection under weak winds and currents. Dissolved oxygen drops to hypoxic levels below the summer thermocline, and the winter high DO layer extends up to the bottom. Chlorophyll-a (Chl-a) is relatively high during late summer in the offshore region, while that in the nearshore regions is very low, which is linked to the anthropogenic stresses from the central east coast of Qatar. The results identified in this study fill an essential gap in the knowledge of regional primary production dynamics.Environmental Science Center (ESC) & Department of Biological and Environmental Sciences (DBES), Qatar University (QU

Impact of Protracted War Crisis on Dental Students: A Comparative Multicountry Cross-sectional Study

BACKGROUND: The impact of conflict and war crisis on dental students is poorly understood. Given the prolonged conflicts and political instability in the Arabic-speaking countries, it is crucial to investigate the effect of these conditions on dental students. This study aimed to assess the impact of protracted war on dental students by comparing the personal, university, and wider context challenges they face across war-affected and unaffected countries. METHODS: A cross-sectional study was conducted including a convenience sample of dental students from 13 universities in 12 Arabic-speaking countries. Respondents were those at entry and exit points of their undergraduate dental training. A self-administered paper questionnaire collected anonymized data on sociodemographics, and personal, university, and wider context challenges that students were facing. Multivariable Poisson regression analyses were carried out. RESULTS: The overall response rate was 64.8%. The mean age was 21.2 (standard deviation = 2.1) years, with 68% of participants being female. After adjusting for age and sex, dental students in Arabic-speaking countries affected by protracted war crisis were significantly more likely to report wider context challenges compared to their counterparts in unaffected countries (n = 2448; beta = 1.12; 95% confidence interval: 1.10-1.13; P < 0.001). DISCUSSION: Dental students in Arabic-speaking countries affected by protracted war crisis were more likely to suffer from wider context challenges such as difficulties in attendance due to the deterioration of security and lack of flexibility of teaching time to accommodate the different circumstances induced by the war crisis. Supporting dental students in areas affected by protracted war crises is needed and may include developing online dental education programs