Search results for: tube expansion

Authors: Camarena Rodriguez C. S., Portocarrero Bonifaz A., Palma Esparza R., Romero Carlos N. A.

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Adobe is a construction material that fulfills the same function as a conventional brick. Widely used since ancient times, it is present in an appreciable percentage of buildings in Latin America. Adobe is a mixture of clay and sand. The interest in the study of the properties of this material arises due to its presence in the infrastructure of hospital´s radiological services, located in places with low economic resources, for the attenuation of radiation. Some materials such as lead and concrete are the most used for shielding and are widely studied in the literature. The present study will determine the mass attenuation coefficient of Adobe. The minimum required thicknesses for the primary and secondary barriers will be estimated for the shielding of radiological facilities where conventional and dental X-rays are performed. For the experimental procedure, an X-ray source emitted direct radiation towards different thicknesses of an Adobe barrier, and a detector was placed on the other side. For this purpose, an UNFORS Xi solid state detector was used, which collected information on the difference of radiation intensity. The initial parameters of the exposure started at 45 kV; and then the tube tension was varied in increments of 5 kV, reaching a maximum of 125 kV. The X-Ray tube was positioned at a distance of 0.5 m from the surface of the Adobe bricks, and the collimation of the radiation beam was set for an area of 0.15 m x 0.15 m. Finally, mathematical methods were applied to determine the mass attenuation coefficient for different energy ranges. In conclusion, the mass attenuation coefficient for Adobe was determined and the approximate thicknesses of the most common Adobe barriers in the hospital buildings were calculated for their later application in the radiological protection.

Keywords: Adobe, attenuation coefficient, radiological protection, shielding, x-rays

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Authors: A. Anandha Selvan, B. Malarvizhi

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In recent year the problem of space debris have become very serious. The mass of the artificial objects in orbit increased quite steadily at the rate of about 145 metric tons annually, leading to a total tally of approximately 7000 metric tons. Now most of space debris object orbiting in LEO region about 97%. The catastrophic collision can be mostly occurred in LEO region, where this collision generate the new debris. Thus, we propose a concept for cleaning the space debris in the region of thermosphere by passing the Extreme Ultraviolet (EUV) radiation to in front of space debris object from the re-orbiter. So in our concept the Extreme Ultraviolet (EUV) radiation will create the thermosphere expansion by reacting with atmospheric gas particles. So the drag is produced in front of the space debris object by thermosphere expansion. This drag force is high enough to slow down the space debris object’s relative velocity. Therefore the space debris object gradually reducing the altitude and finally enter into the earth’s atmosphere. After the first target is removed, the re-orbiter can be goes into next target. This method remove the space debris object without catching debris object. Thus it can be applied to a wide range of debris object without regard to their shapes or rotation. This paper discusses the operation of re-orbiter for removing the space debris in thermosphere region.

Keywords: active space debris removal, space debris, LEO, extreme ultraviolet, re-orbiter, thermosphere

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Authors: Gwi Hyun Lee, Mun Soo Na

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Solar energy has many advantages of infinite and clean source, and also it can be used for reduction of greenhouse gases and environment pollution. Concentrated solar system is a very useful to achieve reasonably high thermal efficiency. Different types of solar concentrating systems have been developed such as parabolic trough and parabolic dish. Conical solar concentrator is one of the most reliable and promising renewable energy systems for higher temperature applications. The objectives of this study were to investigate the influence of flow rate affecting the thermal efficiency of a conical solar collector, which has a double tube absorber placed at focal axis for collecting solar radiation. A conical solar concentrator consists of a conical reflector, which reflects direct solar radiation into an absorber. A double tube absorber was placed at the center of focal axis for collecting the solar radiation reflected from a conical reflector. A dual tracking system consists of a linear actuator and slew drive with driving cycle of 6 seconds. Water was used as circulating fluid, which flows from inlet to outlet of an absorber for collecting solar radiation. Three identical conical solar concentrator systems were installed side by side at the same place for the accurate performance analysis under the same environmental conditions. Performance evaluations were carried out with different volumetric flow rate of 2, 4 and 6 L/min to find the influence of flow rate affecting on thermal efficiency. The results indicated that average thermal efficiency was 73.24%, 81.96%, and 79.78% for each flow rate of 2 L/min, 4 L/min, and 6 L/min. It shows that the flow rate of circulating water has a significant effect on the thermal efficiency of the conical solar concentrator. It is concluded that an optimum flow rate of conical solar concentrator is 6 L/min.

Keywords: conical solar concentrator, performance evaluation, solar energy, solar energy system

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Authors: Cai J. T. Ladd, Mollie F. Duggan-Edwards, Tjeerd J. Bouma, Jordi F. Pages, Martin W. Skov

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Salt marshes are valued for their role in coastal flood protection, carbon storage, and for supporting biodiverse ecosystems. As a biogeomorphic landscape, marshes evolve through the complex interactions between sea level rise, sediment supply and wave/current forcing, as well as and socio-economic factors. Climate change and direct human modification could lead to a global decline marsh extent if left unchecked. Whilst the processes of saltmarsh erosion and expansion are well understood, empirical evidence on the key drivers of long-term lateral marsh dynamics is lacking. In a GIS, saltmarsh areal extent in 25 estuaries across Great Britain was calculated from historical maps and aerial photographs, at intervals of approximately 30 years between 1846 and 2016. Data on the key perceived drivers of lateral marsh change (namely sea level rise rates, suspended sediment concentration, bedload sediment flux rates, and frequency of both river flood and storm events) were collated from national monitoring centres. Continuous datasets did not extend beyond 1970, therefore predictor variables that best explained rate change of marsh extent between 1970 and 2016 was calculated using a Partial Least Squares Regression model. Information about the spread of Spartina anglica (an invasive marsh plant responsible for marsh expansion around the globe) and coastal engineering works that may have impacted on marsh extent, were also recorded from historical documents and their impacts assessed on long-term, large-scale marsh extent change. Results showed that salt marshes in the northern regions of Great Britain expanded an average of 2.0 ha/yr, whilst marshes in the south eroded an average of -5.3 ha/yr. Spartina invasion and coastal engineering works could not explain these trends since a trend of either expansion or erosion preceded these events. Results from the Partial Least Squares Regression model indicated that the rate of relative sea level rise (RSLR) and availability of suspended sediment concentration (SSC) best explained the patterns of marsh change. RSLR increased from 1.6 to 2.8 mm/yr, as SSC decreased from 404.2 to 78.56 mg/l along the north-to-south gradient of Great Britain, resulting in the shift from marsh expansion to erosion. Regional differences in RSLR and SSC are due to isostatic rebound since deglaciation, and tidal amplitudes respectively. Marshes exposed to low RSLR and high SSC likely leads to sediment accumulation at the coast suitable for colonisation by marsh plants and thus lateral expansion. In contrast, high RSLR with are likely not offset deposition under low SSC, thus average water depth at the marsh edge increases, allowing larger wind-waves to trigger marsh erosion. Current global declines in sediment flux to the coast are likely to diminish the resilience of salt marshes to RSLR. Monitoring and managing suspended sediment supply is not common-place, but may be critical to mitigating coastal impacts from climate change.

Keywords: lateral saltmarsh dynamics, sea level rise, sediment supply, wave forcing

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Authors: Kara Terki Ibtissem, Hassaine Hafida, Bellifa Samia

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Introduction: Staphylococcus aureus is one of the species that are most frequently isolated from urinary catheters. The ability to produce a biofilm is an important step in the pathogenesis of these staphylococci; biofilm formation is strongly dependent on the environmental conditions it also depends on the different parameters these biofilms are subjected to. Antiseptics, including ethanol and betadine, are used in clinical practice for disinfection and infection prevention. Recent studies, however, demonstrate that disinfectants may enhance biofilm production in Staphylococci. Methods: In this study, 48 staphylococcus aureus isolated from urinary catheters at the University Hospital Center of Sidi Bel Abbes (in Northwestern Algeria) were analyzed to detect the formation of biofilm by culture on Red Congo Agar (RCA), the Tube Method (TM) and tissue Culture Plate (TCP) techniques, this last was also used to investigate the effect of ethanol and Betadine on the preformed biofilm In a second time to know which environment is most favorable to the formation of the biofilm we perform a statistical test based on the student test by the software R. Results: It has been found that 23 strains produced a bacterial slime on the Congo red medium, 5 strains produced a biofilm by the tube method, 2 of which are highly productive. In addition, 7 strains produced a biofilm on polystyrene micro-plates; this number was higher in the presence of ethanol 70% and ethanol 90% with 19 and 11 biofilm-producing strains, respectively. On the other hand, no biofilm was formed in the presence of Betadine. Conclusion: It is important to examine the response of biofilms following an imposed external constraint, such as disinfectants, in order to develop new strategies to combat bacterial biofilms but also to better control their formation.

Keywords: staphylococcus aureus, biofilm, urinary catheter, ethanol

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Authors: Tingke Wu, Yaping Huang

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Many cities in China have been experiencing serious urban sprawl since the 1980s, which pose great challenges to a country with scare cultivated land and huge population. Because of different social and economic context and development stage, driving forces of urban sprawl in China are quite different from developed countries. Therefore, it is of great importance to probe into urban sprawl driving mechanism in Chinese context. By a comparison study of the background and features of urban sprawl between China and developed countries, this research establishes an analytical framework for sprawl dynamic mechanism in China. By literature review and analyzing data from national statistical yearbook, it then probes into the driving mechanism and the primary cause of urban sprawl. The results suggest that population increase, economic growth, traffic and information technology development lead to rapid expansion of urban space; defects of land institution and lack of effective guidance give rise to low efficiency of urban land use. Moreover, urban sprawl is ultimately attributed to imperfections of policy and institution. On this basis, this research puts forward several sprawl control strategies in Chinese context.

Keywords: China, driving forces, driving mechanism, land institution, urban expansion, urban sprawl

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Authors: Parthasarathy J., Ramshankar C. S.

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Engineering drawings these days play an important role in every part of an industry. By and large, Engineering drawings are influential over every phase of the product development process. Traditionally, drawings are used for communication in industry because they are the clearest way to represent the product manufacturing information. Until recently, manufacturing activities were driven by engineering data captured in 2D paper documents or digital representations of those documents. The need of engineering drawing is inevitable. Still Engineering drawings are disadvantageous in re-entry of data throughout manufacturing life cycle. This document based approach is prone to errors and requires costly re-entry of data at every stage in the manufacturing life cycle. So there is a requirement to eliminate Engineering drawings throughout product development process and to implement 3D Model Based Engineering (3D MBE or 3D MBD). Adopting MBD appears to be the next logical step to continue reducing time-to-market and improve product quality. Ideally, by fully applying the MBD concept, the product definition will no longer rely on engineering drawings throughout the product lifecycle. This project addresses the need of Engineering drawing and its influence in various parts of an industry and the need to implement the 3D Model Based Engineering with its advantages and the technical barriers that must be overcome in order to implement 3D Model Based Engineering. This project also addresses the requirements of neutral formats and its realisation in order to implement the digital product definition principles in a light format. In order to prove the concepts of 3D Model Based Engineering, the screw jack body part is also demonstrated. At ZF Windpower Coimbatore Limited, 3D Model Based Definition is implemented to Torque Arm (Machining and Casting), Steel tube, Pinion shaft, Cover, Energy tube.

Keywords: engineering drawing, model based engineering MBE, MBD, CAD

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Authors: Farah Kanani

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Blue Tide Environmental is a company focused on developing a network of used motor oil recycling facilities across the U.S. They initiated the redesign of its recycling plant in Texas, and aimed to establish an updated carbon footprint of re-refined used motor oils compared to an equivalent product derived from virgin stock that is not re-refined. The aim was to quantify emissions savings of a circular alternative to conventional end-of-life combustion of used motor oil (UMO). To do so, they mandated an ISO-compliant carbon footprint, utilizing complex models requiring geographical and temporal accuracy to accommodate the U.S. refinery market. The quantification of linear and circular flows, proxies for fuel substitution and system expansion for multi-product outputs were all critical methodological choices and were tested through sensitivity analyses. The re-refined system consisted of continuous recycling of UMO and thus, end-of-life is considered non-existent. The unique perspective to this topic will be from a life cycle i.e. holistic one and essentially demonstrate using this example of how a cradle-to-cradle model can be used to quantify a comparative carbon footprint. The intended audience is lubricant manufacturers as the consumers, motor oil industry professionals and other industry members interested in performing a cradle-to-cradle modeling.

Keywords: circularity, used motor oil, re-refining, systems expansion

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Authors: Baboo Ali, Avni Ugur

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Pesticide namely, Diflubenzuron, is tremendously used in pear orchards against different insect pests of pear fruit trees in Turkey. The predatory bug, Anthocoris nemoralis (F.) is found in pear orchard feeding on Cacopsylla pyri (L.) (Homoptera: Psyllidae), is an insect pest of pear fruit trees. In this study, the effectiveness of the above mentioned pesticide on various biological stages of predatory bug were investigated under laboratory conditions of 25±1˚C, 75±5% RH, and photoperiod of 16L: 8D h. Newly emerged 1st, 2nd, 3rd, 4th and 5th instars as well as the female and male stages of the predatory bug were placed on treated petri dishes and their mortality was checked after every 24 hours till the survival of the last individual. Prey consumption of surviving instars as well as the adult stages was determined simultaneously. All biological stages of the predatory bug were fed with eggs of Ephestia kuehniella during the whole research work. Percent hatch of treated eggs was recorded after every 24 hours, and the behavioral test of the male and female stages against Diflubenzuron was also determined using Y-tube olfactometer. Consequently, the mortality rate of 1st, 2nd, 3rd, 4th, and 5th instars was 61.32 %, 67.50%, 74. 91%, 80.11%, and 83.04%, respectively. In case of male and female stages, it has been recorded as 95.47% and 95.50%, respectively. Thus, a significant difference was not found between female and male mortality rates. Prey consumption of 1st, 2nd, 3rd, 4th and 5th surviving instars was noted as 8.01, 11. 72, 13.24, 16.93 and 20.49 number of eggs/day while in females and males, it was 12.05 and 12.71 number of eggs/day, respectively. Hatching ratio of treated eggs of predator was 25.32±4.08. As far as the behavioral test is concerned, it has been indicated that Diflubenzuron has 65% repellent effect on the newly emerged male and female stages of the predatory bug while using Y-tube olfactometer under laboratory conditions.

Keywords: behavior, biological stages, diflubenzuron, effectiveness, pesticide, predatory bug

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Authors: Halima Albalushi, Mohadese Boroojerdi, Murtadha Alkhabori

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Introduction: Maintenance of stem cell properties during culture necessitates the recreation of the natural cell niche. Studies reported the promising outcome of mesenchymal stem cells (MSC) properties maintenance after using extracellular matrix such as CELLstart™, which is the recommended coating material for stem cells cultured in serum-free and xeno-free conditions. Laminin-521 is known as a crucial adhesion protein, which is found in natural stem cell niche, and plays an important role in facilitating the maintenance of self-renewal, pluripotency, standard morphology, and karyotype of human pluripotent stem cells (PSCs). The aim of this study is to investigate the effects of Laminin-521 on human umbilical cord-derived mesenchymal stem cells (UC-MSC) characteristics as a step toward clinical application. Methods: Human MSC were isolated from the umbilical cord via the explant method. Umbilical cord-derived-MSC were cultured in serum-free and xeno-free conditions in the presence of Laminin-521 for six passages. Cultured cells were evaluated by morphology and expansion index for each passage. Phenotypic characterization of UC-MSCs cultured on Laminin-521 was evaluated by assessment of cell surface markers. Results: Umbilical cord derived-MSCs formed small colonies and expanded as a homogeneous monolayer when cultured on Laminin-521. Umbilical cord derived-MSCs reached confluence after 4 days in culture. No statistically significant difference was detected in all passages when comparing the expansion index of UC-MSCs cultured on LN-521 and CELLstart™. Phenotypic characterization of UC-MSCs cultured on LN-521 using flow cytometry revealed positive expression of CD73, CD90, CD105 and negative expression of CD34, CD45, CD19, CD14 and HLA-DR.Conclusion: Laminin-521 is comparable to CELLstart™ in supporting UC-MSCs expansion and maintaining their characteristics during culture in xeno-free and serum-free culture conditions.

Keywords: mesenchymal stem cells, culture, laminin-521, xeno-free serum-free

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Authors: Ahmet Y. Gurkan, Cagatay S. Koksal, Cagri Aydin, U. Oral Unal

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The present paper covers the viscous flow computations for the asymmetric diffuser section of a large, high-speed cavitation tunnel which will be constructed in Istanbul Technical University. The analyses were carried out by using the incompressible Reynold-Averaged-Navier-Stokes equations. While determining the diffuser geometry, a high quality, separation-free flow field with minimum energy loses was particularly aimed. The expansion angle has a critical role on the diffuser hydrodynamic performance. In order obtain a relatively short diffuser length, due to the constructive limitations, and hydrodynamic energy effectiveness, three diffuser sections with varying expansion angles for side and bottom walls were considered. A systematic study was performed to determine the most effective diffuser configuration. The results revealed that the inlet condition of the diffuser greatly affects its flow field. The inclusion of the contraction section in the computations substantially modified the flow topology in the diffuser. The effect of the diffuser flow on the test section flow characteristics was clearly observed. The influence of the introduction of small chamfers at the corners of the diffuser geometry is also presented.

Keywords: asymmetric diffuser, diffuser design, cavitation tunnel, viscous flow, computational fluid dynamics (CFD), rans

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Authors: Bharatkumar Doshi

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Electro-Magnetic Pulse Welding (EMPW) is a solid state welding process carried out at almost room temperature, in which joining is enabled by high impact velocity deformation. In this process, high voltage capacitor’s stored energy is discharged in an EM coil resulting in a damped, sinusoidal current with an amplitude of several hundred kiloamperes. Due to these transient magnetic fields of few tens of Tesla near the coil is generated. As the conductive (tube) part is positioned in this area, an opposing eddy current is induced in this part. Consequently, high Lorentz forces act on the part, leading to acceleration away from the coil. In case of a tube, it gets compressed under forming velocities of more than 300 meters per second. After passing the joining gap it collides with the second metallic joining rod, leading to the formation of a jet under appropriate collision conditions. Due to the prevailing high pressure, metallurgical bonding takes place. A characteristic feature is the wavy interface resulting from the heavy plastic deformations. In the process, the formation of intermetallic compounds which might deteriorate the weld strength can be avoided, even for metals with dissimilar thermal properties. In order to optimize the process parameters like current, voltage, inductance, coil dimensions, workpiece dimensions, air gap, impact velocity, effective plastic strain, shear stress acting in the welding zone/impact zone etc. are very critical and important to establish. These process parameters could be determined by simulation using Finite Element Methods (FEM) in which electromagnetic –structural couple field analysis is performed. The feasibility of welding could thus be investigated by varying the parameters in the simulation using COMSOL. Simulation results shall be applied in performing the preliminary experiments of welding the different alloy steel tubes and/or alloy steel to other materials. The single turn coil (S.S.304) with field shaper (copper) has been designed and manufactured. The preliminary experiments are performed using existing EMPW facility available Institute for Plasma Research, Gandhinagar, India. The experiments are performed at 22kV charged into 64µF capacitor bank and the energy is discharged into single turn EM coil. Welding of axi-symetric components such as aluminum tube and rod has been proven experimentally using EMPW techniques. In this paper EM coil design, manufacturing, Electromagnetic-structural FEM simulation of Magnetic Pulse Welding and preliminary experiment results is reported.

Keywords: COMSOL, EMPW, FEM, Lorentz force

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Authors: Mustarakh Gelfi, Poonam Taneja, Tiedo Vellinga, Delon Hamonangan

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The initial masterplan of New Priok in the Port of Tanjung Priok was developed in 2012 is being updated to cater to new developments and new demands. In the new masterplan (2017), Phase II of development will start from 2035-onwards, depending on the future conditions. This study is about creating a robust masterplan for Phase II, which will remain functional under future uncertainties. The methodology applied in this study is scenario-based planning in the framework of Adaptive Port Planning (APP). Scenario-based planning helps to open up the perspective of the future as a horizon of possibilities. The scenarios are built around two major uncertainties in a 2x2 matrix approach. The two major uncertainties for New Priok port are economics and sustainability awareness. The outcome is four plausible scenarios: Green Port, Business As Usual, Moderate Expansion, and No Expansion. Terminal needs in each scenario are analyzed through traffic analysis and identifying the key cargos and commodities. In conclusion, this study gives the wide perspective for Port of Tanjung Priok for the planning Phase II of the development. The port has to realize that uncertainties persevere and are very likely to influence the decision making as to the future layouts. Instead of ignoring uncertainty, the port needs to make the action plans to deal with these uncertainties.

Keywords: Indonesia Port, port's layout, port planning, scenario-based planning

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Authors: S. V. Boroznin, I. V. Zaporotskova, N. P. Polikarpova

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Studing of nanotubes sorption properties is very important for researching. These processes for carbon and boron nanotubes described in the high number of papers. But the sorption properties of boron containing nanotubes, susch as BC3-nanotubes haven’t been studied sufficiently yet. In this paper we present the results of theoretical research into the mechanism of atomic surface adsorption on the two types of boron-carbon nanotubes (BCNTs) within the framework of an ionic-built covalent-cyclic cluster model and an appropriately modified MNDO quantum chemical scheme and DFT method using B3LYP functional with 6-31G basis. These methods are well-known and the results, obtained using them, were in good agreement with the experiment. Also we studied three position of atom location above the nanotube surface. These facts suggest us to use them for our research and quantum-chemical calculations. We studied the mechanism of sorption of Cl, O and F atoms on the external surface of single-walled BC3 arm-chair nanotubes. We defined the optimal geometry of the sorption complexes and obtained the values of the sorption energies. Analysis of the band structure suggests that the band gap is insensitive to adsorption process. The electron density is located near atoms of the surface of the tube. Also we compared our results with others, which have been obtained earlier for pure carbon and boron nanotubes. The most stable adsorption complex has been between boron-carbon nanotube and oxygen atom. So, it suggests us to make a research of oxygen molecule adsorption on the BC3 nanotube surface. We modeled five variants of molecule orientation above the nanotube surface. The most stable sorption complex has been defined between the oxygen molecule and nanotube when the oxygen molecule is located above the nanotube surface perpendicular to the axis of the tube.

Keywords: Boron-carbon nanotubes, nanostructures, nanolayers, quantum-chemical calculations, nanoengineering

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Authors: Akalework Mengesha

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The adoption of improved agricultural technologies has been connected with higher earnings and lower poverty, enhanced nutritional status, lower staple food prices, and increased employment opportunities for landless laborers. The adoption and extension of the technologies are vastly crucial in that it enables the countries to achieve the millennium development goals (MDG) of reducing extreme poverty and hunger. There are efforts which directed to the enlargement and provision of modern crop varieties in sub-Saharan Africa in the past 30 years. Nevertheless, by and large, the adoption and expansion of rates for improved technologies have insulated behind other regions. This research aims to assess social and economic barriers in the adoption and expansion of agricultural technologies by local communities living around a private agricultural farm in Woliatta Zone, Southern Ethiopia. The study has been carried out among rural households which are located in the three localities selected for the study in the Woliatta zone. Across sectional mixed method, the design was used to address the study objective. The qualitative method was employed (in-depth interview, key informant, and focus group discussion) involving a total of 42 in-depth informants, 17 key-informant interviews, 2 focus group discussions comprising of 10 individuals in each group through purposive sampling techniques. The survey method was mainly used in the study to examine the impact of attitudinal, demographic, and socioeconomic variables on farmers’ adoption of agricultural technologies for quantitative data. The finding of the study revealed that Amibara commercial farm has not made a resolute and well-organized effort to extend agricultural technology to the surrounding local community. A comprehensive agricultural technology transfer scheme hasn’t been put in place by the commercial farm ever since it commenced operating in the study area. Besides, there is an ongoing conflict of interest between the farm and the community, which has kept on widening through time, bounds to be irreversible.

Keywords: adoption, technology transfer, agriculture, barriers

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Authors: Lok Bahadur Shrestha, Narayan Raj Bhattarai, Basudha Khanal

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Introduction: Coagulase-negative staphylococci (CoNS) are the normal commensal of human skin and mucous membranes. The study was carried out to study the prevalence of CoNS among clinical isolates, to characterize them up to species level and to compare the three conventional methods for detection of biofilm formation. Objectives: to characterize the clinically significant coagulase-negative staphylococci up to species level, to compare the three phenotypic methods for the detection of biofilm formation and to study the antimicrobial susceptibility pattern of the isolates. Methods: CoNS isolates were obtained from various clinical samples during the period of 1 year. Characterization up to species level was done using biochemical test and study of biofilm formation was done by tube adherence, congo red agar, and tissue culture plate method. Results: Among 71 CoNS isolates, seven species were identified. S. epidermidis was the most common species followed by S. saprophyticus, S. haemolyticus. Antimicrobial susceptibility pattern of CoNS documented resistance of 90% to ampicillin. Resistance to cefoxitin and ceftriaxone was observed in 55% of the isolates. We detected biofilm formation in 71.8% of isolates. The sensitivity of tube adherence method was 82% while that of congo red agar method was 78%. Conclusion: Among 71 CoNS isolated, S. epidermidis was the most common isolates followed by S. saprophyticus and S. haemolyticus. Biofilm formation was detected in 71.8% of the isolates. All of the methods were effective at detecting biofilm-producing CoNS strains. Biofilm former strains are more resistant to antibiotics as compared to biofilm non-formers.

Keywords: CoNS, congo red agar, bloodstream infections, foreign body-related infections, tissue culture plate

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Authors: Surajit Chattopadhyay

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Accelerated expansion of the current universe is well-established in the literature. Dark energy and modified gravity are two approaches to account for this accelerated expansion. In the present work, we consider scalar field models of dark energy, namely, tachyon and DBI essence in the framework of chameleon Brans-Dicke cosmology. The equation of state parameter is reconstructed and the subsequent cosmological implications are studied. We examined the stability for the obtained solutions of the crossing of the phantom divide under a quantum correction of massless conformally invariant fields and we have seen that quantum correction could be small when the phantom crossing occurs and the obtained solutions of the phantom crossing could be stable under the quantum correction. In the subsequent phase, we have established a correspondence between the NHDE model and the quintessence, the DBI-essence and the tachyon scalar field models in the framework of chameleon Brans–Dicke cosmology. We reconstruct the potentials and the dynamics for these three scalar field models we have considered. The reconstructed potentials are found to increase with the evolution of the universe and in a very late stage they are observed to decay.

Keywords: dark energy, holographic principle, modified gravity, reconstruction

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Authors: Marshet Girmay

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Local community involvement is widely considered vital for the sustainability of heritage management. Yet, it is often the case that heritage-related projects lag behind in community involvement. In the Semien Mountains the creation, first, and expansion, later, of the National Park has led to several conflicts with the local communities that for centuries have inhabited the area. Local communities have only been passive actors in the plans to expand the Park set up by UNESCO and by local decision makers. This paper investigates the causes that led the Gich community, one of the communities affected by the Park’s expansion, to refuse the resettlement plan offered by the authorities. Qualitative research methods were employed, including document analysis, community conference and interview of informants. The paper shows that although the local community of Gich was highly attached to the Park’s heritage assets, their level of involvement in the heritage management was very low due to shortcomings in the design and implementation of official policies. Therefore, their attitude towards the Park’s managers has been until the present one of mistrust and opposition. The paper recommends to policy-makers a series of measures more sensitive towards local communities, such as that the development agencies act as true communication facilitators and regional authorities nurture sincere relationships with the locals.

Keywords: Gich, heritage management, local communities, Semen Mountains, sustainability, UNESCO, world heritage site

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Authors: Elena M. Kopteva, Pavlina Jaluvkova, Zdenek Stuchlik

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The question of constructing a consistent model of the cosmological black hole remains to be unsolved and still attracts the interest of cosmologists as far as it is important in a wide set of research problems including the problem of the black hole horizon dynamics, the problem of interplay between cosmological expansion and local gravity, the problem of structure formation in the early universe etc. In this work, the model of the cosmological black hole is built on the basis of the exact solution of the Einstein equations for the spherically symmetric inhomogeneous dust distribution in the approach of the mass function use. Possible trajectories for massive particles and photons near the black hole immersed in the nonstatic dust cosmological background are investigated in frame of the obtained model. The reference system of distant galaxy comoving to cosmological expansion combined with curvature coordinates is used, so that the resulting metric becomes nondiagonal and involves both proper ‘cosmological’ time and curvature spatial coordinates. For this metric the geodesic equations are analyzed for the test particles and photons, and the respective trajectories are built.

Keywords: exact solutions for Einstein equations, Lemaitre-Tolman-Bondi solution, cosmological black holes, particle and photon trajectories

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Authors: Rachita Lal

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Urban sprawl is a significant contributor to land use change in developing countries, where urbanization rates are high. The most important driver of environmental changes is also considered to be the shift in land use and land cover. Our local and regional land managers must carefully analyze urbanization and its effects on cities to make the best choices. This study uses satellite imagery to examine how urbanization affects the local ecosystem through geographic expansion. The following research focuses on the effects of city growth on the local environment, land use, and Land cover. The primary focus of this research is to study, To understand the role of urbanization on city expansion. To study the impact of spatial growth of urban areas on the Land cover. In this paper, the GIS tool will be used to analyze. For this purpose, four digital images are used for the years 2000, 2005, 2011, and 2019. The use of the approach in the Bhubaneswar Urban Core, one of the fastest developing and planned cities in India, has proved that it is highly beneficial and successful for monitoring urban sprawl. It offers a helpful tool for quantitative assessment, which is crucial for determining the spatial dynamics, variations, and changes of urban sprawl patterns in quickly increasing regions.

Keywords: LULC, urbanization, environment impact assessment, spatial growth

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Authors: Rameesha Javaid

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Agriculture is the backbone of the economy of the province of Balochistan which is known as the ‘fruit basket’ of Pakistan. Its climate zones comprising highlands and plateaus, dependent on rain water, are more suited for the production of deciduous fruit. The vagaries of weather and more so the persistent droughts prompted the government to announce flat rates of electricity bills per month irrespective of the size of the farm, quantum or water used and the category of crop group. That has, no doubt, resulted in increased cropping intensity, more production and employment but has enormously burdened the official exchequer which picks up the residual bills in certain percentages amongst the federal and provincial governments and the local electricity company. This study tests the desirability of continuing the subsidy in the present mode. Optimization of social welfare of farmers has been the focus of the study with emphasis on the contribution of positive externalities and distortions caused in terms of negative externalities. By using the optimization technique with due allowance for distortions, it has been established that the subsidy calls for limiting policy distortions as they cause sub-optimal utilization of the tube well subsidy and improved policy programming. The sensitivity analysis with changed rankings of contributing variables towards social welfare does not significantly change the result. Therefore it leads to the net findings and policy recommendations of significantly reducing the subsidy size, correcting and curtailing policy distortions and targeting the subsidy grant more towards small farmers to generate more welfare by saving a sizeable amount from the subsidy for investment in the wellbeing of the farmers in rural Balochistan.

Keywords: distortion, policy distortion, socio-cultural distortion, social welfare, subsidy

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Authors: Sihem Ferah, Karima Messaoudi

Abstract:

Tourism is far from of being apprehended as a closed space limited to a defined area. The different experiences in the world have shown that tourism should be set up in the city, where locals can meet tourists, to know their history, tradition, culture, and relationship with the territory. In Algeria, the strategy employed in the context of promoting tourism is to integrate sustainable tourism based on a set of instruments such as the tourism expansion areas named ZET. Unfortunately, these areas have promoted the economic and environmental dimension, neglecting the social dimension which is the responsible of the community well–being. The case of Taleza village in Collo (characterized by its various potential) demonstrates clearly this paradox between the planned tourism in the ZET in Taleza as an economic product and the Tourism lived inside this local environment. When people by their genius and innovative action have succeeded to create an alternative tourism (social tourism) developed through guesthouses, sales of local products which have participated in promoting local Tourism Taleza. The aim of this research is to find a strong position between the planned space ZET and the village of Taleža where sustainable tourism can be installed that encourages the social membership, preservation of the natural heritage of Taleza and generates economic benefits that will ensure a local development of the village and will succeed in maintain sustainable tourism on its territory.

Keywords: sustainable tourism, local development, rural areas, tourism expansion zone

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Authors: Y. D. Lim, K. S. Yap, K. T. Ooi

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In recent years, environmental issue has been a hot topic in the world, especially the global warming effect caused by conventional non-environmentally friendly refrigerants has increased. Several studies of a more energy-efficient and environmentally friendly refrigeration system have been conducted in order to tackle the issue. In search of a better refrigeration system, CO2 refrigeration system has been proposed as a better option. However, the high throttling loss involved during the expansion process of the refrigeration cycle leads to a relatively low efficiency and thus the system is impractical. In order to improve the efficiency of the refrigeration system, it is suggested by replacing the conventional expansion valve in the refrigeration system with an expander. Based on this issue, a new type of expander-compressor combined unit, named Cross Vane Expander-Compressor (CVEC) was introduced to replace the compressor and the expansion valve of a conventional refrigeration system. A mathematical model was developed to calculate the performance of CVEC, and it was found that the machine is capable of saving the energy consumption of a refrigeration system by as much as 18%. Apart from energy saving, CVEC is also geometrically simpler and more compact. To further improve its efficiency, optimization study of the device is carried out. In this report, several design parameters of CVEC were chosen to be the variables of optimization study. This optimization study was done in a simulation program by using complex optimization method, which is a direct search, multi-variables and constrained optimization method. It was found that the main design parameters, which was shaft radius was reduced around 8% while the inner cylinder radius was remained unchanged at its lower limit after optimization. Furthermore, the port sizes were increased to their upper limit after optimization. The changes of these design parameters have resulted in reduction of around 12% in the total frictional loss and reduction of 4% in power consumption. Eventually, the optimization study has resulted in an improvement in the mechanical efficiency CVEC by 4% and improvement in COP by 6%.

Keywords: complex optimization method, COP, cross vane expander-compressor, CVEC, design optimization, direct search, energy saving, improvement, mechanical efficiency, multi variables

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Authors: Piotr Wisniewski, Sławomir Dykas

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Condensation has a negative impact on turbomachinery efficiency in many energy processes.In technical applications, it is often impossible to dry the working fluid at the nozzle inlet. One of the most popular working fluid is atmospheric air that always contains water in form of steam, liquid, or ice crystals. Moreover, it always contains some amount of suspended particles which influence the phase change process. It is known that the phenomena of evaporation or condensation are connected with release or absorption of latent heat, what influence the fluid physical properties and might affect the machinery efficiency therefore, the phase transition has to be taken under account. This researchpresents an attempt to evaluate the impact of solid and liquid particles suspended in the air on the expansion of moist air in a low expansion rate, i.e., with expansion rate, P≈1000s⁻¹. The numerical study supported by analytical and experimental research is presented in this work. The experimental study was carried out using an in-house experimental test rig, where nozzle was examined for different inlet air relative humidity values included in the range of 25 to 51%. The nozzle was tested for a supersonic flow as well as for flow with shock waves induced by elevated back pressure. The Schlieren photography technique and measurement of static pressure on the nozzle wall were used for qualitative identification of both condensation and shock waves. A numerical model validated against experimental data available in the literature was used for analysis of occurring flow phenomena. The analysis of the suspended particles number, diameter, and character (solid or liquid) revealed their connection with heterogeneous condensation importance. If the expansion of fluid without suspended particlesis considered, the condensation triggers so called condensation wave that appears downstream the nozzle throat. If the solid particles are considered, with increasing number of them, the condensation triggers upwind the nozzle throat, decreasing the condensation wave strength. Due to the release of latent heat during condensation, the fluid temperature and pressure increase, leading to the shift of normal shock upstream the flow. Owing relatively large diameters of the droplets created during heterogeneous condensation, they evaporate partially on the shock and continues to evaporate downstream the nozzle. If the liquid water particles are considered, due to their larger radius, their do not affect the expanding flow significantly, however might be in major importance while considering the compression phenomena as they will tend to evaporate on the shock wave. This research proves the need of further study of phase change phenomena in supersonic flow especially considering the interaction of droplets with the aerodynamic waves in the flow.

Keywords: aerodynamics, computational fluid dynamics, condensation, moist air, multi-phase flows

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Authors: S. Kida

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We consider the flow of an incompressible viscous fluid in a precessing sphere whose spin and precession axes are orthogonal to each other. The flow is characterized by two non-dimensional parameters, the Reynolds number Re and the Poincare number Po. For which values of (Re, Po) will the flow approach a steady state from an arbitrary initial condition? To answer it we are searching the instability boundary of the steady states in the whole (Re, Po) plane. Here, we focus the rapidly rotating and weakly precessing limit, i.e., Re >> 1 and Po << 1. The steady flow was obtained by the asymptotic expansion for small ε=Po Re¹/² << 1. The flow exhibits nearly a solid-body rotation in the whole sphere except for a thin boundary layer which develops over the sphere surface. The thickness of this boundary layer is of O(δ), where δ=Re⁻¹/², except where two circular critical bands of thickness of O(δ⁴/⁵) and of width of O(δ²/⁵) which are located away from the spin axis by about 60°. We perform the linear stability analysis of the steady flow. We assume that the disturbances are localized in the critical bands and make an expansion analysis in terms of ε to derive the eigenvalue problem for the growth rate of the disturbance, which is solved numerically. As the solution, we obtain an asymptote of the stability boundary as Po=28.36Re⁻⁰.⁸. This agrees excellently with the corresponding laboratory experiments and numerical simulations. One of the most popular instability mechanisms so far is the parametric instability, which turns out, however, not to give the correct stability boundary. The present instability is different from the parametric instability.

Keywords: boundary layer, critical band, instability, precessing sphere

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Authors: Siamak Yaghoubi, Mohammad Reza Abootorabi, Hamid Kayalha

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Objective: The study was aimed to evaluate the applicability of the Cobra Perilaryngeal Airway (Cobra PLATM) for patients under general anesthesia and also compare result with the Laryngeal Mask Airway (LMA). Methods: Seventy three obese and overweight patients were included in the study. The patients were randomly assigned to either LMA or Cobra PLATM. Time required for intubation, successful intubation attempt, airway sealing pressure, the incidences of complications including blood staining, sore throat and dysphagia were assessed and noted. Results: Thirty six and thirty seven patients were allocated randomly to either LMA or Cobra PLATM, respectively. Most of the patients were male and were in Mallampati Class II airway in both groups. The first attempt and overall insertion success for the Cobra PLATM was significantly more frequent compared to the LMA (p<0.05). Tube insertion was more successful (Cobra PLATM, 94%; LMA™, 77%; P = 0.027) with the Cobra PLATM. The insertion times were similar with the Cobra PLATM and LMA™ (Cobra PLATM, 29.94±16.35s; LMA™, 27.00±7.88s). The airway sealing pressure in the Cobra PLATM (24.80±0.90 H2O) was significantly more than LMA™ (19.13 ±0.58 H2O, p<0.001). Sore throat was more frequent in the LMA™ groups that did not reach statistical significance (Fisher’s exact test, P = 0.33). Incidences of blood staining on airway tube were seen for both groups that was higher in the Cobra PLATM group (Fisher’s exact test, P = 0.02). Incidence of dysphagia was not different between the two groups. Conclusion: The CobraPLA™ was found to be safe and low complications, better airway sealing and high rate of the first insertion success for suing in obese and overweight patients. The study recommended using the CobraPLA™ as a rescue device in an emergency situation among obese and overweight patients.

Keywords: CobraPLA™, flexible laryngeal mask airway, obese patients, perilaryngeal airway

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Authors: Mehrnaz Alibeikloo, Hadi Khabbaz, Behzad Fatahi

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Probabilistic analysis has become one of the most popular methods to quantify and manage geotechnical risks due to the spatial variability of soil input parameters. The correlation length is one of the key factors of quantifying spatial variability of soil parameters which is defined as a distance within which the random variables are correlated strongly. This paper aims to assess the impact of correlation length on the long-term settlement of soft soils improved with preloading. The concept of 'worst-case' spatial correlation length was evaluated by determining the probability of failure of a real case study of Vasby test fill. For this purpose, a finite difference code was developed based on axisymmetric consolidation equations incorporating the non-linear elastic visco-plastic model and the Karhunen-Loeve expansion method. The results show that correlation length has a significant impact on the post-construction settlement of soft soils in a way that by increasing correlation length, probability of failure increases and the approach to asymptote.

Keywords: Karhunen-Loeve expansion, probability of failure, soft soil settlement, 'worst case' spatial correlation length

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Authors: Anna Martin, Raffael Osen

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The demand for fish from aquaculture is constantly growing. Concurrently, due to a shortage of fishmeal caused by extensive overfishing, fishmeal substitution by plant proteins is getting increasingly important for the production of sustainable aquafeed. Several research studies evaluated the impact of plant protein meals, concentrates or isolates on fish health and fish feed quality. However, these protein raw materials often require elaborate and expensive manufacturing and their availability is limited. Rapeseed press cake (RPC) – a side product of de-oiling processes – exhibits a high potential as a plant-based fishmeal alternative in fish feed for carnivorous species due to its availability, low costs and protein content. In order to produce aquafeed with RPC, it is important to systematically assess i) inclusion levels of RPC with similar pellet qualities compared to fishmeal containing formulations and ii) how extrusion parameters can be adjusted to achieve targeted pellet qualities. However, the effect of RPC on extrusion system parameters and pellet quality has only scarcely been investigated. Therefore, the aim of this study was to evaluate the impact of feed formulation, extruder barrel temperature (90, 100, 110 °C) and screw speed (200, 300, 400 rpm) on extrusion system parameters and the physical properties of fish feed pellets. A co-rotating pilot-scale twin screw extruder was used to produce five iso-nitrogenous feed formulations: a fish meal based reference formulation including 16 g/100g fishmeal and four formulations in which fishmeal was substituted by RPC to 25, 50, 75 or 100 %. Extrusion system parameters, being product temperature, pressure at the die, specific mechanical energy (SME) and torque, were monitored while samples were taken. After drying, pellets were analyzed regarding to optical appearance, sectional and longitudinal expansion, sinking velocity, bulk density, water stability, durability and specific hardness. In our study, the addition of minor amounts of RPC already had high impact on pellet quality parameters, especially on expansion but only marginally affected extrusion system parameters. Increasing amounts of RPC reduced sectional expansion, sinking velocity, bulk density and specific hardness and increased longitudinal expansion compared to a reference formulation without RPC. Water stability and durability were almost not affected by RPC addition. Moreover, pellets with rapeseed components showed a more coarse structure than pellets containing only fishmeal. When the adjustment of barrel temperature and screw speed was investigated, it could be seen that the increase of extruder barrel temperature led to a slight decrease of SME and die pressure and an increased sectional expansion of the reference pellets but did almost not affect rapeseed containing fish feed pellets. Also changes in screw speed had little effects on the physical properties of pellets however with raised screw speed the SME and the product temperature increased. In summary, a one-to-one substitution of fishmeal with RPC without the adjustment of extrusion process parameters does not result in fish feed of a designated quality. Therefore, a deeper knowledge of raw materials and their behavior under thermal and mechanical stresses as applied during extrusion is required.

Keywords: extrusion, fish feed, press cake, rapeseed

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Authors: Berhanu Keno Terfa

Abstract:

To understand the consequences of urbanization, accurate, and long-term representation of urban dynamics is essential. Remote sensing data from various multi-temporal satellite images viz., TM (1987), TM (1995), ETM+ (2005) and OLI (2017) were used. An integrated method, landscape metrics, built-up density, and urban growth type analysis were employed to analyze the pattern, process, and overall growth status in the city. The result showed that the built-up area had increased by 541.3% between 1987 and 2017, at an average annual increment of 8.9%. The area of urban expansion in a city has tripled during the 2005-2017 period as compared to 187- 1995. The major growth took place in the east and southeast directions during 1987–1995 period, whereas predominant built-up development was observed in south and southeast direction during 1995–2017 period. The analysis using landscape metrics and urban typologies showed that Hawassa experienced a fragmented and irregular spatiotemporal urban growth patterns, mostly by extension, suggesting a strong tendency towards sprawl in the past three decades.

Keywords: Hawassa, spatial patterns, remote sensing, multi-temporal, urban sprawl

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Authors: Sarra K. Ikhlef, Onita Basu

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Natural organic matter (NOM) removal efficiency using drinking water treatment biological filters can be highly influenced by backwashing conditions. Backwashing has the ability to remove the accumulated biomass and particles in order to regenerate the biological filters' removal capacity and prevent excessive headloss buildup. A lab scale system consisting of 3 biological filters was used in this study to examine the implications of different backwash strategies on biological filtration performance. The backwash procedures were evaluated based on their impacts on dissolved organic carbon (DOC) removals, biological filters’ biomass, backwash water volume usage, and particle removal. Results showed that under nutrient limited conditions, the simultaneous use of air and water under collapse pulsing conditions lead to a DOC removal of 22% which was significantly higher (p>0.05) than the 12% removal observed under water only backwash conditions. Employing a bed expansion of 20% under nutrient supplemented conditions compared to a 30% reference bed expansion while using the same amount of water volume lead to similar DOC removals. On the other hand, utilizing a higher bed expansion (40%) lead to significantly lower DOC removals (23%). Also, a backwash strategy that reduced the backwash water volume usage by about 20% resulted in similar DOC removals observed with the reference backwash. The backwash procedures investigated in this study showed no consistent impact on biological filters' biomass concentrations as measured by the phospholipids and the adenosine tri-phosphate (ATP) methods. Moreover, none of these two analyses showed a direct correlation with DOC removal. On the other hand, dissolved oxygen (DO) uptake showed a direct correlation with DOC removals. The addition of the extended terminal subfluidization wash (ETSW) demonstrated no apparent impact on DOC removals. ETSW also successfully eliminated the filter ripening sequence (FRS). As a result, the additional water usage resulting from implementing ETSW was compensated by water savings after restart. Results from this study provide insight to researchers and water treatment utilities on how to better optimize the backwashing procedure for the goal of optimizing the overall biological filtration process.

Keywords: biological filtration, backwashing, collapse pulsing, ETSW

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