Search results for: Increased intrauterine pressure

Authors: Mohamed Elkashouty, Mohamed Elkammar, Mohamed Gomma, Menal Elminiami

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Lake Bardawil is considered as one of the major morphological features of northern Sinai. It represents the largest fish production lake for export in Egypt. Nineteen and thirty one samples were collected from lake water during winter and summer (2005). TDS, cations, anions, Cd, Cu, Fe, Mn, Zn, Ni, Co and Pb concentrations were measured within winter and summer seasons. During summer, in the eastern sector of the lake, TDS concentration is decreased due northeastern part (38000 ppm), it is attributed to dilution from seawater through Boughaz II. The TDS concentration increased generally in the central and southern parts of the lake (44000 and 42000 ppm, respectively). It is caused by they are far from dilution from seawater, disconnected water body, shallow depth (mean 2 m), and high evaporation rate. In the western sector, the TDS content ranged from low (38000 ppm) in the northeastern part to high (50000 ppm) in the western part. Generally, the TDS concentration in the western sector is higher than those in the eastern. It is attributed to low volume of water body for the former, high evaporation rate, and therefore increase in TDS content in the lake water.During winter season, in the eastern sector, the wind velocity is high which enhance the water current to inflow into the lake through Boughaz I and II. The resultant water lake is diluted by seawater and rainfall in the winter season. The TDS concentration increased due southern part of the lake (42000 ppm) and declined in the northern part (36000 ppm). The concentration of Co, Ni, Pb, Fe, Cd, Zn, Cu, Mn and Pb within winter and summery seasons, in lake water are low, which considered as background concentrations with respect to seawater. Therefore, there are no industrial, agricultural and sanitary wastewaters dump into the lake. This confirms the statement that has been written at the entrance of Lake Bardawil at El-Telool area "Lake Bardawil, one of the purest lakes in the world". It indicate that the Lake Bardawil is excellent area for fish production for export (current state) and is the second main fish source in Egypt after the Mediterranean Sea after the illness of Lake Manzala.

Keywords: lake Bardawil, water quality, major ions, toxic metals

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Authors: Jesus Ruano, Francesc Xavier Trias, Asensi Oliva

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A three-dimensional incompressible Large Eddy Simulation (LES) is performed to compute the hydrodynamic field around a pair of tandem cylinders. Symmetry-preserving schemes will be used during this simulation in conjunction with Finite Volume Method (FVM) to obtain the hydrodynamic field around the selected geometry. A set of results consisting of pressure and velocity and the combination of them will be stored at different surfaces near the cylinders as the initial input for the second part of the study. A post-processing of the obtained results based on Ffowcs-Williams and Hawkings (FWH) equation with a Fourier Transform of the acoustic sources will be used to compute noise at several probes located far away from the region where the hydrodynamics are computed. Directivities as well as spectral profile of the obtained acoustic field will be analyzed.

Keywords: far-field noise, Ffowcs-Williams and Hawkings, finite volume method, large eddy simulation, long-span bodies

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Authors: Kianoosh Ahadi, Mustafa Ergil

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In this study, the event of vibrations caused by vortexes and the distribution of induced hydrodynamic forces due to vortexes on the sliding gate valves has been investigated. For this reason, a sliding valve with the help of computational fluid dynamics (CFD) software was simulated in two-dimensional )2D(, where the flow and turbulence equations were solved for three different valve openings (full, half, and 16.7 %) models. The variety of vortexes formed within the vicinity of the valve structure was investigated based on time where the trend of fluctuations and their occurrence regions have been detected. From the gathered solution dataset of the numerical simulations, the pressure coefficient (CP), the lift force coefficient (CL), the drag force coefficient (CD), and the momentum coefficient due to hydrodynamic forces (CM) were examined, and relevant figures were generated were from these results, the vortex-induced vibrations were analyzed.

Keywords: induced vibrations, computational fluid dynamics, sliding gate valves, vortexes

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Authors: Rajib Mia, Badam Singh Kushvah

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In this present paper, we use the photogravitational version of the restricted three body problem (RTBP) in binary systems. In the photogravitational RTBP, an infinitesimal particle (dust grain) is moving under the gravitational attraction and radiation pressure from the two bigger primaries. The third particle does not affect the motion of two bigger primaries. The zero-velocity curves, zero-velocity surfaces and their projections on the plane are studied. We have used existing analytical method to solve the equations of motion. We have obtained the Lagrangian points in some binary stellar systems. It is found that mass reduction factor affects the Lagrangian points. The linear stability of Lagrangian points is studied and found that these points are unstable. Moreover, trajectories of the infinitesimal particle at the triangular points are studied.

Keywords: binary systems, Lagrangian points, linear stability, photogravitational RTBP, trajectories

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Authors: Pedro Llanos, Diego García

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Spaceflight is considered the last frontier in terms of science, technology, and engineering. But it is also the next frontier in terms of human physiology and performance. After more than 200,000 years humans have evolved under earth’s gravity and atmospheric conditions, spaceflight poses environmental stresses for which human physiology is not adapted. Hypoxia, accelerations, and radiation are among such stressors, our research involves suborbital flights aiming to develop effective countermeasures in order to assure sustainable human space presence. The physiologic baseline of spaceflight participants is subject to great variability driven by age, gender, fitness, and metabolic reserve. The objective of the present study is to characterize different physiologic variables in a population of STEM practitioners during an aerobatic flight. Cardiovascular and pulmonary responses were determined in Science Astronaut Candidates (SACs) during unusual attitude aerobatic flight indoctrination. Physiologic data recordings from 20 subjects participating in high-G flight training were analyzed. These recordings were registered by wearable sensor-vest that monitored electrocardiographic tracings (ECGs), signs of dysrhythmias or other electric disturbances during all the flight. The same cardiovascular parameters were also collected approximately 10 min pre-flight, during each high-G/unusual attitude maneuver and 10 min after the flights. The ratio (pre-flight/in-flight/post-flight) of the cardiovascular responses was calculated for comparison of inter-individual differences. The resulting tracings depicting the cardiovascular responses of the subjects were compared against the G-loads (Gs) during the aerobatic flights to analyze cardiovascular variability aspects and fluid/pressure shifts due to the high Gs. In-flight ECG revealed cardiac variability patterns associated with rapid Gs onset in terms of reduced heart rate (HR) and some scattered dysrhythmic patterns (15% premature ventricular contractions-type) that were considered as triggered physiological responses to high-G/unusual attitude training and some were considered as instrument artifact. Variation events were observed in subjects during the +Gz and –Gz maneuvers and these may be due to preload and afterload, sudden shift. Our data reveal that aerobatic flight influenced the breathing rate of the subject, due in part by the various levels of energy expenditure due to the increased use of muscle work during these aerobatic maneuvers. Noteworthy was the high heterogeneity in the different physiological responses among a relatively small group of SACs exposed to similar aerobatic flights with similar Gs exposures. The cardiovascular responses clearly demonstrated that SACs were subjected to significant flight stress. Routine ECG monitoring during high-G/unusual attitude flight training is recommended to capture pathology underlying dangerous dysrhythmias in suborbital flight safety. More research is currently being conducted to further facilitate the development of robust medical screening, medical risk assessment approaches, and suborbital flight training in the context of the evolving commercial human suborbital spaceflight industry. A more mature and integrative medical assessment method is required to understand the physiology state and response variability among highly diverse populations of prospective suborbital flight participants.

Keywords: g force, aerobatic maneuvers, suborbital flight, hypoxia, commercial astronauts

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Authors: Jhoanne Pedres Boñgol, Zhang Liu, Yuyin Qiu, King Lun Yeung

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Flexible ceramic sorbent material can be a viable technology to capture and recover emulsified fats, oils, and grease (FOG) that often cause sanitary sewer overflows. This study investigates the sorption capacity and recovery rate of ceramic material in surfactant-stabilized oil-water emulsion by synthesizing silica aerogel: SiO₂–X via acid-base sol-gel method followed by ambient pressure drying. The SiO₂–X is amorphous, microstructured, lightweight, flexible, and highly oleophilic. It displays spring-back behavior apparent at 80% compression with compressive strength of 0.20 MPa and can stand a weight of 1000 times its own. The contact angles measured at 0° and 177° in oil and water, respectively, confirm its oleophilicity and hydrophobicity while its thermal stability even at 450 °C is confirmed via TGA. In pure oil phase, the qe,AV. of 1x1 mm SiO₂–X is 7.5 g g⁻¹ at tqe= 10 min, and a qe,AV. of 6.05 to 6.76 g g⁻¹ at tqe= 24 hrs in O/W emulsion. The filter ceramic can be reused 50 x with 75-80 % FOG recovery by manual compression.

Keywords: adsorption, aerogel, emulsion, FOG

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Authors: Robert K. Hillyard, Jonathan Thomas, Brett A. Story

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Compressed Stabilized Earth Blocks (CSEB) are masonry units that combine soil, sand, stabilizer, and water under pressure to form an earth block. These CSEB’s offer a cost-effective building solution for remote construction, using local resources and labor to minimize transportation and material costs. However, CSEB’s, and earthen construction generally have not been widely adopted as standardized construction materials. One shortcoming is the difficulty in standardizing strength values of CSEB units and systems due to the inherent variations in mix design, including production compression. This research presents findings on compressive strengths of full-scale CSEB’s from 60 different mix designs as a function of the amount of cement, sand, soil, and water added to the mixture. The full-scale results are compared with CSEB cylinder cores.

Keywords: CSEB, compressive strength, earth construction, mix design

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Authors: N. G. Thangan, A. B. Deoghare, P. M. Padole

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Computational Fluid Dynamics (CFD) aids in modeling the prototype of a real world processes. CFD approach is useful in predicting the fluid flow, heat transfer mass transfer and other flow related phenomenon. In present study, hydrodynamic characteristics of gas-solid cylindrical fluidized bed is compared with conical fluidized beds. A 2D fluidized bed consists of different configurations of particle size of iron oxide, bed height and superficial velocities of nitrogen. Simulations are performed to capture the complex physics associated with it. The Eulerian multiphase model is prepared in ANSYS FLUENT v.14 which is used to simulate fluidization process. It is analyzed with nitrogen as primary phase and iron oxide as secondary phase. The bed hydrodynamics is assessed prominently to examine effect on fluidization time, pressure drop, minimum fluidization velocity, and gas holdup in the system.

Keywords: fluidized bed, bed hydrodynamics, Eulerian multiphase approach, computational fluid dynamics

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Authors: Tine Cencič, Marko Hočevar, Brane Širok

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An experimental investigation has been made to detect cavitation in pump–storage hydro power plant prototype suffering from cavitation in pump mode. Vibrations and acoustic emission on the housing of turbine bearing and pressure fluctuations in the draft tube were measured and the corresponding signals have been recorded and analyzed. The analysis was based on the analysis of high-frequency content of measured variables. The pump-storage hydro power plant prototype has been operated at various input loads and Thoma numbers. Several estimators of cavitation were evaluated according to coefficient of determination between Thoma number and cavitation estimators. The best results were achieved with a compound discharge coefficient cavitation estimator. Cavitation estimators were evaluated in several intervals of frequencies. Also, a prediction of cavitation erosion was made in order to choose the appropriate maintenance and repair periods.

Keywords: cavitation erosion, turbine, cavitation measurement, fluid dynamics

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Authors: Mengjia Zhi, Xingmei Wei, Xiang Gao, Shiyang Liu, Zhiran Huang, Li Yang, Jing Sun

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Background: To understand the consumption trend of opioid analgesics and the consumption adequacy of opioid analgesic treatment for moderate to severe pain in China, as well as the pain control level of China with international perspective. Importance: To author’s best knowledge, this is the first study in China to measure the adequacy of opioid analgesic treatment for moderate to severe pain considering disease pattern and with the standardized pain treatment guideline. Methods: A retrospective analysis was carried out to show the consumption frequency (daily defined doses, DDDs) of opioid analgesics and its trend in China from 2006 to 2016. Adequacy of consumption measure (ACM) was used to measure the number of needed morphine equivalents and the overall adequacy of opioid analgesic treatment of moderate to severe pain in China, and compared with international data. Results: The consumption frequency of opioid analgesics (DDDs) in China increased from 13,200,000 DDDs in 2006 to 44,200,000 DDDs in 2016, and showed an increasing trend. The growth rate was faster at first, especially in 2013, then slowed down, decreased slightly in 2015. The ACM of China increased from 0.0032 in 2006 to 0.0074 in 2016, with an overall trend of growth. The ACM level of China has been always a very poor level during 2006-2016. Conclusion: The consumption of opioid analgesics for the treatment of moderate to severe pain in China has always been inadequate. There is a huge gap between China and the international level. There are many reasons behind this problem, which lie in different aspects, including medical staff, patients and the public, health systems and social & cultural aspects. It is necessary to strengthen the training and education of medical staff and the patients, to use mass media to disseminate scientific knowledge of pain management, to encourage communications between doctors and patients, to improve regulatory system for the controlled medicines and the overall health systems, and to balance the regulatory goal for avoidance of abuse, and the social goal of meeting the increasing needs of the people for better life.

Keywords: opioid analgesics, adequate consumption measure, pain control, China

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Authors: Sunha Ahn

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Intimate relationships have constructed our embodied experiences and emotional memories, which can become grounded as practical knowledge to some extent and play a critical role in social medicine, particularly, in our well-being and mental health. In South Africa, such relational factors are significant for young women and girls in their emotional development period of time, especially, working as the existence of social and relational pressures over feminine sexual health and choices. This, in turn, brings about the absence/lack of communication in intimate relationships, especially with their parents, which leads to a vicious cycle in sexual health behaviour choices. Drawing upon sociological and socio-anthropological understandings of HIV-related issues, this study provides narrative threads of evidence about South African teenage mothers from early-dating debuted to HIV infection. Their stories consist of a visualised figure in chronicle order, illustrating embodied journeys of sexual health choices surrounding uncommunicative relationships and socially-suppressive environments. Methodologically, this qualitative study explored data from mixed online methods: 1) a case study analysing online comments (N = 12,763) on the South African Springster's website, run by the UK-based NGO, namely, Girl Effect; and 2) In-depth online interviews (N = 21) were conducted with young SA women and girls (16-28 ages) recruited in Cape Town, Pretoria, and Johannesburg, SA. Participants consist of both those living with HIV and without. Ethical approval was gained via the College of Social Sciences Ethical Committee at the University of Glasgow, and informed consent was obtained verbally and in writing from participants in due course. Data were thematically applied to an iteratively developed codebook and analysed. There are three kinds of typical pressures as relational factors for them, including peer pressure, partners or boyfriends, and parents’ reactions. Under the patriarchal and religious-devoted social atmospheres, these relationships work as a source of scaredness among young women and girls who could not talk about their sexual health concerns and rights. Such an inability to communicate with intimate relationships, eventually, emerges as a perpetuated or taken-for-granted social environment in South Africa, insistently leading to an increase in unwanted pregnancies or new HIV infections in young South African women and girls. In this sense, this study reveals the pressing need for open communication between generations with accurate information about HIV/AIDS. This also implies that the sociological feminist praxes in South Africa would help eliminate HIV-related stigma as well as construct open space to reduce gender-based violence and sexually-transmitted infection. Ultimately, this will be a road for supporting sexually healthy decisions and well-being across South African generations.

Keywords: HIV, young women, South Africa, intimate relationships, communication, social medicine

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Authors: R. Fardid, R. Coppes

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Introduction: In mediastinal radiotherapy and to a lesser extend also in total-body irradiation (TBI) radiation exposure may lead to development of cardiac diseases. Radiation-induced heart disease is dose-dependent and it is characterized by a loss of cardiac function, associated with progressive heart cells degeneration. We aimed to determine the in-vivo radiation effects on fibronectin, ColaA1, ColaA2, galectin and TGFb1 gene expression levels in left ventricle heart tissues of rats after irradiation. Material and method: Four non-treatment adult Wistar rats as control group (group A) were selected. In group B, 4 adult Wistar rats irradiated to 20 Gy single dose of 150 Mev proton beam locally in heart only. In heart plus lung irradiate group (group C) 4 adult rats was irradiated by 50% of lung laterally plus heart radiation that mentioned in before group. At 8 weeks after radiation animals sacrificed and left ventricle heart dropped in liquid nitrogen for RNA extraction by Absolutely RNA® Miniprep Kit (Stratagen, Cat no. 400800). cDNA was synthesized using M-MLV reverse transcriptase (Life Technologies, Cat no. 28025-013). We used Bio-Rad machine (Bio Rad iQ5 Real Time PCR) for QPCR testing by relative standard curve method. Results: We found that gene expression of fibronectin in group C significantly increased compared to control group, but it was not showed significant change in group B compared to group A. The levels of gene expressions of Cola1 and Cola2 in mRNA did not show any significant changes between normal and radiation groups. Changes of expression of galectin target significantly increased only in group C compared to group A. TGFb1 expressions in group C more than group B showed significant enhancement compared to group A. Conclusion: In summary we can say that 20 Gy of proton exposure of heart tissue may lead to detectable damages in heart cells and may distribute function of them as a component of heart tissue structure in molecular level.

Keywords: gene expression, heart damage, proton irradiation, radiotherapy

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Authors: Shyh-Ming Chern, Hung-Chi Tu

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One way to utilize biomass is to thermochemically convert it into gases and chemicals. For conversion of biomass, glucose is a particularly popular model compound for cellulose, or more generally for biomass. The present study takes a different approach by employing lactic acid as the model compound for cellulose. Since lactic acid and glucose have identical elemental composition, they are expected to produce similar results as they go through the conversion process. In the current study, lactic acid was thermochemically converted to assess its reactivity and reaction mechanism in subcritical and supercritical water, by using a 16-ml autoclave reactor. The major operating parameters investigated include: The reaction temperature, from 673 to 873 K, the reaction pressure, 10 and 25 MPa, the dosage of oxidizing agent, 0 and 0.5 chemical oxygen demand, and the concentration of lactic acid in the feed, 0.5 and 1.0 M. Gaseous products from the conversion were generally found to be comparable to those derived from the conversion of glucose.

Keywords: lactic acid, subcritical water, supercritical water, thermochemical conversion

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Authors: Jichi Wu

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Though fast fashion and consumption do boost the economy and push the progress of the industry, they have also caused a mass of waste, which has led to great pressure on the environment. This project mainly focuses on how to develop new sustainable textile and fashion design through recycling, upcycling, and reusing. Substantial field researches were implemented from the very beginning, including collecting reusable material from recycling centers. Hot-pressed composite materials, hand-cutting, and weaving were finally selected as the core material/method of this project after attempts and experiments. Four pieces of menswear, as well as hats and other decorative products made from wasted foams and fabrics, were successfully manufactured. Results show that foam is not only possible for furniture but also for clothing. It helps people to realize that foam is warm, heatproof, anti-slippery, and crease-resistant. So, all advantages could inspire people that even common materials could have new usage and are worthy of upcycling.

Keywords: sustainable design, foam, upcycling, life cycle, textile design

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Authors: Y. L. Sun, L. Shao, Y. Zhao, H. X. Zhou, W. Z. Lu, J. Li, D. W. Zuo

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This study introduces an ice fixed-abrasive polishing (IFAP) technology. Using silica solution IFAP pad and Al2O3 IFAP pad, orthogonal tests were performed on polishing high-definition display panel glass, respectively. The results show that the polishing efficiency and effect polished with silica solution IFAP pad are better than those polished with Al2O3 IFAP pad. The optimized silica solution IFAP parameters are: polishing pressure 0.1MPa, polishing time 40min, table velocity 80r/min, and the ratio of accelerator and slurry 1:10. Finally, the IFAP mechanism was studied and it suggests by complicated analysis that IFAP is comprehensive effect of mechanical removal and microchemical reaction, combined with fixed abrasive polishing and free abrasive polishing.

Keywords: ice fixed-abrasive polishing, high-definition display panel glass, material removal rate, surface roughness

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Authors: Nicholas Bayfield, Liam Bibo, Charley Budgeon, Robert Larbalestier, Tom Briffa

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Introduction: Stress hyperglycaemia is common following cardiac surgery. Its optimal management is uncertain and may differ by diabetic status. This study assesses the in-hospital glycaemic management of cardiac surgery patients and associated postoperative outcomes. Methods: A retrospective cohort analysis of all patients undergoing cardiac surgery at Fiona Stanley Hospital from February 2015 to May 2019 was undertaken. Management and outcomes of hyperglycaemia following cardiac surgery were assessed. Follow-up was assessed to 1 year postoperatively. Multivariate regression modelling was utilised. Results: 1050 non-diabetic patients and 689 diabetic patients were included. In the non-diabetic cohort, patients with mild (peak blood sugar level [BSL] < 14.3), transient stress hyperglycaemia managed without insulin were not at an increased risk of wound-related morbidity (P=0.899) or mortality at 1 year (P=0.483). Insulin management was associated with wound-related readmission to hospital (P=0.004) and superficial sternal wound infection (P=0.047). Prolonged or severe stress hyperglycaemia was predictive of hospital re-admission (P=0.050) but not morbidity or mortality (P=0.546). Diabetes mellitus was an independent risk factor 1-year mortality (OR; 1.972 [1.041–3.736], P=0.037), graft harvest site wound infection (OR; 1.810 [1.134–2.889], P=0.013) and wound-related readmission (OR; 1.866 [1.076–3.236], P=0.026). In diabetics, postoperative peak BSL > 13.9mmol/L was predictive of graft harvest site infections (OR; 3.528 [1.724-7.217], P=0.001) and wound-related readmission OR; 3.462 [1.540-7.783], P=0.003) regardless of modality of management. A peak BSL of 10.0-13.9 did not increase the risk of morbidity/mortality compared to a peak BSL of < 10.0 (P=0.557). Diabetics with a peak BSL of 13.9 or less did not have significantly increased morbidity/mortality outcomes compared to non-diabetics (P=0.418). Conclusion: In non-diabetic patients, transient mild stress hyperglycaemia following cardiac surgery does not uniformly require treatment. In diabetic patients, postoperative hyperglycaemia with peak BSL exceeding 13.9mmol/L was associated with wound-related morbidity and hospital readmission following cardiac surgery.

Keywords: cardiac surgery, pulmonary embolism, pulmonary embolectomy, cardiopulmonary bypass

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Authors: Wu Xingchun, Chen Xi

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Nowadays, China's building energy consumption constitutes 25% of the total energy consumption, half of which was caused by air conditioning in both summer and winter. The ventilation system in Chinese traditional residence, which is totally passive and environmentally friendly, works effectively to create comfortable indoor environment. The research on the ventilation system in Chinese traditional residence can provide advancements to architecture design and energy savings to the society. Through field investigation, case analysis, strategy proposing and other methods, it comes out that the location and layout, the structure system and the design of atrium are the most important elements for a good ventilation system. Taking every factor into consideration, techniques are deployed extensively such as the organization of draught, the design of the thermal pressure ventilation system and the application of modern materials. With the enlightenment of the ventilation system in Chinese traditional residence, we can take effective measures to achieve low energy consumption and sustainable architecture.

Keywords: ventilation system, chinese traditional residence, energy consumption, sustainable architecture

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Authors: S. K. Kakraliya, R. D. Jat, H. S. Jat, P. C. Sharma, M. L. Jat

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The traditional rice-wheat (RW) system in the IGP of South Asia is tillage, water, energy, and capital intensive. Coupled with more pumping of groundwater over the years to meet the high irrigation water requirement of the RW system has resulted in over-exploitation of groundwater. Replacement of traditional rice with less water crops such as maize under climate-smart agriculture (CSA) based management (tillage, crop establishment and residue management) practices are required to promote sustainable intensification. Furthermore, inefficient nutrient management practices are responsible for low crop yields and nutrient use efficiencies in maize-wheat (MW) system. A 7-year field experiment was conducted in farmer’s participatory strategic research mode at Taraori, Karnal, India to evaluate the effects of tillage and crop establishment (TCE) methods, residue management, mungbean integration, and nutrient management practices on crop yields, water productivity and profitability of MW system. The main plot treatments included four combinations of TCE, residue and mungbean integration [conventional tillage (CT), conventional tillage with mungbean (CT + MB), permanent bed (PB) and permanent bed with MB (PB + MB] with three nutrient management practices [farmer’s fertilizer practice (FFP), recommended dose of fertilizer (RDF) and site-specific nutrient management (SSNM)] using Nutrient Expert® as subplot treatments. System productivity, water use efficiency (WUE) and net returns under PB + MB were significantly increased by 25–30%, 28–31% and 35–40% compared to CT respectively, during seven years of experimentation. The integration of MB in MW system contributed ~25and ~ 28% increases in system productivity and net returns compared with no MB, respectively. SSNM based nutrient management increased the mean (averaged across 7 yrs) system productivity by 12- 15% compared with FFP. The study revealed that CSA based sustainable intensification (PB + MB) and SSNM approach provided opportunities for enhancing crop productivity, WUE and profitability of the MW system in India.

Keywords: Conservation Agriculture, Precision water and nutrient management, Permanent beds, Crop yields

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Authors: Victoria L. Chester, Usha Kuruganti

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The forest industry is a major economic sector of Canada and also one of the most dangerous industries for workers. The use of mechanized mobile forestry harvesting machines has successfully reduced the incidence of injuries in forest workers related to manual labor. However, these machines have also created additional concerns, including a high machine operation learning curve, increased the length of the workday, repetitive strain injury, cognitive load, physical and mental fatigue, and increased postural loads due to sitting in a confined space. It is critical to obtain objective performance data for employers to develop appropriate work practices for this industry, however ergonomic field studies of this industry are lacking mainly due to the difficulties in obtaining comprehensive data while operators are cutting trees in the woods. The purpose of this study was to establish a measurement and experimental protocol to examine the effects of worker skill level and movement training speed (joystick crane speed) on harvesting performance using a forestry simulator. A custom wrist angle measurement device was developed as part of the study to monitor Euler angles during operation of the simulator. The device of the system consisted of two accelerometers, a Bluetooth module, three 3V coin cells, a microcontroller, a voltage regulator and an application software. Harvesting performance and crane data was provided by the simulator software and included tree to frame collisions, crane to tree collisions, boom tip distance, number of trees cut, etc. A pilot study of 3 operators with various skill levels was tested to identify factors that distinguish highly skilled operators from novice or intermediate operators. Dependent variables such as reaction time, math skill, past work experience, training movement speed (e.g. joystick control speeds), harvesting experience level, muscle activity, and wrist biomechanics were measured and analyzed. A 10-channel wireless surface EMG system was used to monitor the amplitude and mean frequency of 10 upper extremity muscles during pre and postperformance on the forestry harvest stimulator. The results of the pilot study showed inconsistent changes in median frequency pre-and postoperation, but there was the increase in the activity of the flexor carpi radialis, anterior deltoid and upper trapezius of both arms. The wrist sensor results indicated that wrist supination and pronation occurred more than flexion and extension with radial-ulnar rotation demonstrating the least movement. Overall, wrist angular motion increased as the crane speed increased from slow to fast. Further data collection is needed and will help industry partners determine those factors that separate skill levels of operators, identify optimal training speeds, and determine the length of training required to bring new operators to an efficient skill level effectively. In addition to effective and employment training programs, results of this work will be used for selective employee recruitment strategies to improve employee retention after training. Further, improved training procedures and knowledge of the physical and mental demands on workers will lead to highly trained and efficient personnel, reduced risk of injury, and optimal work protocols.

Keywords: EMG, forestry, human factors, wrist biomechanics

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Authors: Laura O’Halloran, Zhipeng Cao, Clare M. Kelly, Hugh Garavan, Robert Whelan

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Reaction time (RT) variability on cognitive tasks provides the index of the efficiency of executive control processes (e.g. attention and inhibitory control) and is considered to be a hallmark of clinical disorders, such as attention-deficit disorder (ADHD). Increased RT variability is associated with structural and functional brain differences in children and adults with various clinical disorders, as well as poorer task performance accuracy. Furthermore, the strength of functional connectivity across various brain networks, such as the negative relationship between the task-negative default mode network and task-positive attentional networks, has been found to reflect differences in RT variability. Although RT variability may provide an index of attentional efficiency, as well as being a useful indicator of neurological impairment, the brain substrates associated with RT variability remain relatively poorly defined, particularly in a healthy sample. Method: Firstly, we used the intra-individual coefficient of variation (ICV) as an index of RT variability from “Go” responses on the Stop Signal Task. We then examined the functional and structural neural correlates of ICV in a large sample of 14-year old healthy adolescents (n=1719). Of these, a subset had elevated symptoms of ADHD (n=80) and was compared to a matched non-symptomatic control group (n=80). The relationship between brain activity during successful and unsuccessful inhibitions and gray matter volume were compared with the ICV. A mediation analysis was conducted to examine if specific brain regions mediated the relationship between ADHD symptoms and ICV. Lastly, we looked at functional connectivity across various brain networks and quantified both positive and negative correlations during “Go” responses on the Stop Signal Task. Results: The brain data revealed that higher ICV was associated with increased structural and functional brain activation in the precentral gyrus in the whole sample and in adolescents with ADHD symptoms. Lower ICV was associated with lower activation in the anterior cingulate cortex (ACC) and medial frontal gyrus in the whole sample and in the control group. Furthermore, our results indicated that activation in the precentral gyrus (Broadman Area 4) mediated the relationship between ADHD symptoms and behavioural ICV. Conclusion: This is the first study first to investigate the functional and structural correlates of ICV collectively in a large adolescent sample. Our findings demonstrate a concurrent increase in brain structure and function within task-active prefrontal networks as a function of increased RT variability. Furthermore, structural and functional brain activation patterns in the ACC, and medial frontal gyrus plays a role-optimizing top-down control in order to maintain task performance. Our results also evidenced clear differences in brain morphometry between adolescents with symptoms of ADHD but without clinical diagnosis and typically developing controls. Our findings shed light on specific functional and structural brain regions that are implicated in ICV and yield insights into effective cognitive control in healthy individuals and in clinical groups.

Keywords: ADHD, fMRI, reaction-time variability, default mode, functional connectivity

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Authors: Zerarka Hizia, Akchiche Mustapha, Prunier Florent

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The landslide of Ain El Hammam (AEH) is characterized by a complex geology and a high hydrogeology hazard. AEH's perpetual reactivation compels us to look closely at its triggers and to better understand the mechanisms of its evolution in mass and in depth. This study builds a numerical model to simulate the influencing factors such as precipitation, non-saturation, and pore pressure fluctuations, using Plaxis software. For a finer analysis of instabilities, we use Hill's criterion, based on the sign of the second order work, which is the most appropriate material stability criterion for non-associated elastoplastic materials. The results of this type of calculation allow us, in theory, to predict the shape and position of the slip surface(s) which are liable to ground movements of the slope, before reaching the rupture given by the plastic limit of Mohr Coulomb. To validate the numerical model, an analysis of inclinometer measures is performed to confirm the direction of movement and kinematic of the sliding mechanism of AEH’s slope.

Keywords: landslide, second order work, precipitation, inclinometers

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Authors: Dharminder Singh, Sanjeev Yadav, Pravakar Mohanty

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In this work, study of temperature profile in a pilot scale air bubbling fluidized bed (ABFB) gasifier for rice husk gasification was carried out. Effects of different factors such as multiple cyclones, gas cooling system, ventilate gas pipe length, and catalyst on temperature profile was examined. ABFB gasifier used in this study had two sections, one is bed section and the other is freeboard section. River sand was used as bed material with air as gasification agent, and conventional charcoal as start-up heating medium in this gasifier. Temperature of different point in both sections of ABFB gasifier was recorded at different ER value and ER value was changed by changing the feed rate of biomass (rice husk) and by keeping the air flow rate constant for long durational of gasifier operation. ABFB with double cyclone with gas coolant system and with short length ventilate gas pipe was found out to be optimal gasifier design to give temperature profile required for high gasification performance in long duration operation. This optimal design was tested with different ER values and it was found that ER of 0.33 was most favourable for long duration operation (8 hr continuous operation), giving highest carbon conversion efficiency. At optimal ER of 0.33, bed temperature was found to be stable at 700 °C, above bed temperature was found to be at 628.63 °C, bottom of freeboard temperature was found to be at 600 °C, top of freeboard temperature was found to be at 517.5 °C, gas temperature was found to be at 195 °C, and flame temperature was found to be 676 °C. Temperature at all the points showed fluctuations of 10 – 20 °C. Effect of catalyst i.e. dolomite (20% with sand bed) was also examined on temperature profile, and it was found that at optimal ER of 0.33, the bed temperature got increased to 795 °C, above bed temperature got decreased to 523 °C, bottom of freeboard temperature got decreased to 548 °C, top of freeboard got decreased to 475 °C, gas temperature got decreased to 220 °C, and flame temperature got increased to 703 °C. Increase in bed temperature leads to higher flame temperature due to presence of more hydrocarbons generated from more tar cracking at higher temperature. It was also found that the use of dolomite with sand bed eliminated the agglomeration in the reactor at such high bed temperature (795 °C).

Keywords: air bubbling fluidized bed gasifier, bed temperature, charcoal heating, dolomite, flame temperature, rice husk

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Authors: Mokhtar Labiod, Nabil Ikhlef, Keltoum Bouherine, Olivier Leroy

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A numerical model for the radio-frequency (RF) Argon discharge chamber is developed to simulate the low pressure low temperature inductively coupled plasma. This model will be of fundamental importance in the design of the plasma magnetic control system. Electric and magnetic fields inside the discharge chamber are evaluated by solving a magnetic vector potential equation. To start with, the equations of the ideal magnetohydrodynamics theory will be presented describing the basic behaviour of magnetically confined plasma and equations are discretized with finite element method in cylindrical coordinates. The discharge chamber is assumed to be axially symmetric and the plasma is treated as a compressible gas. Plasma generation due to ionization is added to the continuity equation. Magnetic vector potential equation is solved for the electromagnetic fields. A strong dependence of the plasma properties on the discharge conditions and the gas temperature is obtained.

Keywords: direct-coupled model, magnetohydrodynamic, modelling, plasma torch simulation

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Authors: Shuo Li, Yannick Coffinier, Chann Lagadec, Fabrizio Cleri, Katsuhiko Nishiguchi, Akira Fujiwara, Soo Hyeon Kim, Nicolas Clément

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The need for single cell detection and analysis techniques has increased in the past decades because of the heterogeneity of individual living cells, which increases the complexity of the pathogenesis of malignant tumors. In the search for early cancer detection, high-precision medicine and therapy, the technologies most used today for sensitive detection of target analytes and monitoring the variation of these species are mainly including two types. One is based on the identification of molecular differences at the single-cell level, such as flow cytometry, fluorescence-activated cell sorting, next generation proteomics, lipidomic studies, another is based on capturing or detecting single tumor cells from fresh or fixed primary tumors and metastatic tissues, and rare circulating tumors cells (CTCs) from blood or bone marrow, for example, dielectrophoresis technique, microfluidic based microposts chip, electrochemical (EC) approach. Compared to other methods, EC sensors have the merits of easy operation, high sensitivity, and portability. However, despite various demonstrations of low limits of detection (LOD), including aptamer sensors, arrayed EC sensors for detecting single-cell have not been demonstrated. In this work, a new technique based on 20-nm-thick nanopillars array to support cells and keep them at ideal recognition distance for redox-labeled aptamers grafted on the surface. The key advantages of this technology are not only to suppress the false positive signal arising from the pressure exerted by all (including non-target) cells pushing on the aptamers by downward force but also to stabilize the aptamer at the ideal hairpin configuration thanks to a confinement effect. With the first implementation of this technique, a LOD of 13 cells (with5.4 μL of cell suspension) was estimated. In further, the nanosupported cell technology using redox-labeled aptasensors has been pushed forward and fully integrated into a single-cell electrochemical aptasensor array. To reach this goal, the LOD has been reduced by more than one order of magnitude by suppressing parasitic capacitive electrochemical signals by minimizing the sensor area and localizing the cells. Statistical analysis at the single-cell level is demonstrated for the recognition of cancer cells. The future of this technology is discussed, and the potential for scaling over millions of electrodes, thus pushing further integration at sub-cellular level, is highlighted. Despite several demonstrations of electrochemical devices with LOD of 1 cell/mL, the implementation of single-cell bioelectrochemical sensor arrays has remained elusive due to their challenging implementation at a large scale. Here, the introduced nanopillar array technology combined with redox-labeled aptamers targeting epithelial cell adhesion molecule (EpCAM) is perfectly suited for such implementation. Combining nanopillar arrays with microwells determined for single cell trapping directly on the sensor surface, single target cells are successfully detected and analyzed. This first implementation of a single-cell electrochemical aptasensor array based on Brownian-fluctuating redox species opens new opportunities for large-scale implementation and statistical analysis of early cancer diagnosis and cancer therapy in clinical settings.

Keywords: bioelectrochemistry, aptasensors, single-cell, nanopillars

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Authors: Karuna Tuchinda, Sasithon Bland

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This work investigates the wear of a steam turbine blade coated with titanium nitride (TiN), and compares to the wear of uncoated blades. The coating is deposited on by physical vapor deposition (PVD) method. The working conditions of the blade were simulated and surface temperature and pressure values as well as flow velocity and flow direction were obtained. This data was used in the finite element wear model developed here in order to predict the wear of the blade. The wear mechanisms considered are erosive wear due to particle impingement and fluid jet, and fatigue wear due to repeated impingement of particles and fluid jet. Results show that the life of the TiN-coated blade is approximately 1.76 times longer than the life of the uncoated one.

Keywords: physical vapour deposition, steam turbine blade, titanium-based coating, wear prediction

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Authors: Radmila Maksimovic, Sonja Ketin, Rade Biocanin, Jelena Maksimovic

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The abnormal conditions of life and work genetic factors often play a major role in incidence of diabetes-diabetes, heart disease and vascular disease, jaundice, and post traumatic stress. Trauma and post traumatic stress are most common in the displaced persons,and the focus of this paper is to shed light on this issue in former Yugoslavia, Yugoslavia and now in our country. This is caused by increased beta-cell sensitivity to viruses, the development of autoimmune antibodies against its own pancreascells, degenerative changes in cells that r esult in change of structure and insulin. In this paper, we dealt with traumatic events and long-term psycho social consequences for internally displaced persons, several years after displacement, and found a high level of PTSD symptoms. This stress is present in almost 1/3 of internally displaced persons, and every sixth person is suffering from PTSD in the past. Respondents generally suffer from symptoms of intrusion, but there was a large number of symptoms, avoidance and increased arousal. We also found that gender, age andeducation related to the symptoms. Females, and older respondents and internally displaced persons with lower levels of education how a higher level of PTSD symptoms, especially symptoms of intrusion and increase darousal. It is a highly traumatized sample in which more than 1/2 of respondents experienced more than three traumatic events in life,although the number of traumas experienced before, during and after the conflict varies.We found that during the war, internally displaced persons haveexperienced more traumatic events compared with the periodbefore and after the conflict. Trauma are different in type. No significant correlation between the number of experienced trauma and PTSD, suggesting that it is necessary to further study the structure of past traumas and the intermediary effects of certain risk factors and protective factors.

Keywords: living environment, displaced persons, jaundice, diabetes, trauma, diabetic hypertension, post-traumatic stress (PTSD), treatment

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Authors: Edip Kemal, Sheshov Vlatko, Bojadjieva Julijana, Bogdanovic ALeksandra, Gjorgjeska Irena

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The wave propagation phenomenon in porous domains is of great importance in the field of geotechnical earthquake engineering. In these kinds of problems, the elastic waves propagate from the interior to the exterior domain and require special treatment at the computational level since apart from displacement in the solid-state there is a p-wave that takes place in the pore water phase. In this paper, a study on the implementation of multiphase finite elements is presented. The proposed algorithm is implemented in the ANSYS finite element software and tested on one-dimensional wave propagation considering both pore pressure wave propagation and displacement fields. In the simulation of porous media such as soils, the behavior is governed largely by the interaction of the solid skeleton with water and/or air in the pores. Therefore, coupled problems of fluid flow and deformation of the solid skeleton are considered in a detailed way.

Keywords: wave propagation, multiphase model, numerical methods, finite element method

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Authors: Gulshan Sachdeva, Vaibhav Jain, S. S. Kachhwaha

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Cascade refrigeration systems employ series of single stage vapor compression units which are thermally coupled with evaporator/condenser cascades. Different refrigerants are used in each of the circuit depending on the optimum characteristics shown by the refrigerant for a particular application. In the present research study, a steady state thermodynamic model is developed which simulates the working of an actual cascade system. The model provides COP and all other system parameters like total compressor work, temperature, pressure, enthalpy and entropy at different state points. The working fluid in Low Temperature Circuit (LTC) is CO2 (R744) while ammonia (R717), propane (R290), propylene (R1270), R404A and R12 are the refrigerants in High Temperature Circuit (HTC). The performance curves of ammonia, propane, propylene, and R404A are compared with R12 to find its nearest substitute. Results show that ammonia is the best substitute of R12.

Keywords: cascade system, refrigerants, thermodynamic model, production engineering

Procedia PDF Downloads 345

Authors: María José Carrero, Ana M. Borreguero, Juan F. Rodríguez, María M. Velencoso, Ángel Serrano, María Jesús Ramos

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Flame-retardants are incorporated in different materials in order to reduce the risk of fire, either by providing increased resistance to ignition, or by acting to slow down combustion and thereby delay the spread of flames. In this work, polyether polyols with fire retardant properties were synthesized due to their wide application in the polyurethanes formulation. The combustion of polyurethanes is primarily dependent on the thermal properties of the polymer, the presence of impurities and formulation residue in the polymer as well as the supply of oxygen. There are many types of flame retardants, most of them are phosphorous compounds of different nature and functionality. The addition of these compounds is the most common method for the incorporation of flame retardant properties. The employment of glycerol phosphate sodium salt as initiator for the polyol synthesis allows obtaining polyols with phosphate groups in their structure. However, some of the critical points of the use of glycerol phosphate salt are: the lower reactivity of the salt and the necessity of a solvent (dimethyl sulfoxide, DMSO). Thus, the main aim in the present work was to determine the amount of the solvent needed to get a good solubility of the initiator salt. Although the anionic polymerization mechanism of polyether formation is well known, it seems convenient to clarify the role that DMSO plays at the starting point of the polymerization process. Regarding the fact that the catalyst deprotonizes the hydroxyl groups of the initiator and as a result of this, two water molecules and glycerol phosphate alkoxide are formed. This alkoxide, together with DMSO, has to form a homogeneous mixture where the initiator (solid) and the propylene oxide (PO) are soluble enough to mutually interact. The addition rate of PO increased when the solvent/initiator ratios studied were increased, observing that it also made the initiation step shorter. Furthermore, the molecular weight of the polyol decreased when higher solvent/initiator ratios were used, what revealed that more amount of salt was activated, initiating more chains of lower length but allowing to react more phosphate molecules and to increase the percentage of phosphorous in the final polyol. However, the final phosphorous content was lower than the theoretical one because only a percentage of salt was activated. On the other hand, glycerol phosphate disodium salt was still partially insoluble in DMSO studied proportions, thus, the recovery and reuse of this part of the salt for the synthesis of new flame retardant polyols was evaluated. In the recovered salt case, the rate of addition of PO remained the same than in the commercial salt but a shorter induction period was observed, this is because the recovered salt presents a higher amount of deprotonated hydroxyl groups. Besides, according to molecular weight, polydispersity index, FT-IR spectrum and thermal stability, there were no differences between both synthesized polyols. Thus, it is possible to use the recovered glycerol phosphate disodium salt in the same way that the commercial one.

Keywords: DMSO, fire retardants, glycerol phosphate disodium salt, recovered initiator, solvent

Procedia PDF Downloads 269

Authors: Lim Kar Sing, Siti Nur Afifah Azraai, Norhazilan Md Noor, Nordin Yahaya

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Polymeric composites are being increasingly used as repair material for repairing critical infrastructures such as building, bridge, pressure vessel, piping and pipeline. Technique in repairing damaged pipes is one of the major concerns of pipeline owners. Considerable researches have been carried out on the repair of corroded pipes using composite materials. This article attempts a short review of the subject matter to provide insight into various techniques used in repairing corroded pipes, focusing on a wide range of composite repair systems. These systems including pre-cured layered, flexible wet lay-up, pre-impregnated, split composite sleeve and flexible tape systems. Both advantages and limitations of these repair systems were highlighted. Critical technical aspects have been discussed through the current standards and practices. Research gaps and future study scopes in achieving more effective design philosophy are also presented.

Keywords: composite materials, pipeline, repair technique, polymers

Procedia PDF Downloads 503