Search results for: engineering of communication and transportation system

Authors: Weirong Wang, Shenghong Huang, Xisheng Luo, Zhenyu Li

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Material mixing process and related dynamic issues at extreme compressing conditions have gained more and more concerns in last ten years because of the engineering appealings in inertial confinement fusion (ICF) and hypervelocity aircraft developments. However, there lacks models and methods that can handle fully coupled turbulent material mixing and complex fluid evolution under conditions of high energy density regime up to now. In aspects of macro hydrodynamics, three numerical methods such as direct numerical simulation (DNS), large eddy simulation (LES) and Reynolds-averaged Navier–Stokes equations (RANS) has obtained relative acceptable consensus under the conditions of low energy density regime. However, under the conditions of high energy density regime, they can not be applied directly due to occurrence of dissociation, ionization, dramatic change of equation of state, thermodynamic properties etc., which may make the governing equations invalid in some coupled situations. However, in view of micro/meso scale regime, the methods based on Molecular Dynamics (MD) as well as Monte Carlo (MC) model are proved to be promising and effective ways to investigate such issues. In this study, both classical MD and first-principle based electron force field MD (eFF-MD) methods are applied to investigate Richtmyer-Meshkov Instability of metal Lithium and gas Hydrogen (Li-H2) interface mixing at different shock loading speed ranging from 3 km/s to 30 km/s. It is found that: 1) Classical MD method based on predefined potential functions has some limits in application to extreme conditions, since it cannot simulate the ionization process and its potential functions are not suitable to all conditions, while the eFF-MD method can correctly simulate the ionization process due to its ‘ab initio’ feature; 2) Due to computational cost, the eFF-MD results are also influenced by simulation domain dimensions, boundary conditions and relaxation time choices, etc., in computations. Series of tests have been conducted to determine the optimized parameters. 3) Ionization induced by strong shock compression has important effects on Li-H2 interface evolutions of RMI, indicating a new micromechanism of RMI under conditions of high energy density regime.

Keywords: first-principle, ionization, molecular dynamics, material mixture, Richtmyer-Meshkov instability

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Authors: Vladimíra Kňazovická, Mária Dovičičová, Miroslava Kačániová, Margita Čanigová

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The aim of the study was to test the storage of bee pollen at room temperature and in cold store, and to describe microorganisms originated from it. Fresh bee pollen originating in West Slovakia was collected in May 2010. It was tested for presence of particular microbial groups using dilution plating method, and divided into two parts with different storage (in cold store and at room temperature). Microbial analyses of pollen were repeated after one year of storage. Several bacterial strains were isolated and tested using Gram staining, for catalase and fructose-6-phosphate-phosphoketolase presence, and by rapid ID 32A (BioMérieux, France). Micromycetes were identified at genus level. Fresh pollen contained coliform bacteria, which were not detected after one year of storage in both ways. Total plate count (TPC) of aerobes and anaerobes and of yeasts in fresh bee pollen exceeded 5.00 log CFU/g. TPC of aerobes and anaerobes decreased below 2.00 log CFU/g after one year of storage in both ways. Count of yeasts decreased to 2.32 log CFU/g (at room temperature) and to 3.66 log CFU/g (in cold store). Microscopic filamentous fungi decreased from 3.41 log CFU/g (fresh bee pollen) to 1.13 log CFU/g (at room temperature) and to 1.89 log CFU/g (in cold store). In fresh bee pollen, 12 genera of micromycetes were identified in the following order according to their relative density: Penicillium > Mucor > Absidia > Cladosporium, Fusarium > Alternaria > Eurotium > Aspergillus, Rhizopus > Emericella > Arthrinium and Mycelium sterilium. After one year at room temperature, only three genera were detected in bee pollen (Penicillium > Aspergillus, Mucor) and after one year in cold store, seven genera were detected (Mucor > Penicillium, Emericella > Aspergillus, Absidia > Arthrinium, Eurotium). From the plates designated for anaerobes, eight colonies originating in fresh bee pollen were isolated. Among them, a single yeast isolate occurred. Other isolates were G+ bacteria, with a total of five rod shaped. In three out of these five, catalase was absent and fructose-6-phosphate-phosphoketolase was present. Bacterial isolates originating in fresh pollen belonged probably to genus Bifidobacterium or relative genera, but their identity was not confirmed unequivocally. In general, cold conditions are suitable for maintaining the natural properties of foodstuffs for a longer time. Slight decrease of microscopic fungal number and diversity was recorded in cold temperatures compared with storage at room temperature.

Keywords: bacteria, bee product, microscopic fungi, biosystems engineering

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Authors: J. F. Reinoso-Gordo, F. J. Ariza-López, A. Mozas-Calvache, J. L. García-Balboa, S. Eddargani

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The DEMs quality may depend on several factors such as data source, capture method, processing type used to derive them, or the cell size of the DEM. The two most important capture methods to produce regional-sized DEMs are photogrammetry and LiDAR; DEMs covering entire countries have been obtained with these methods. The quality of these DEMs has traditionally been evaluated by the national cartographic agencies through punctual sampling that focused on its vertical component. For this type of evaluation there are standards such as NMAS and ASPRS Positional Accuracy Standards for Digital Geospatial Data. However, it seems more appropriate to carry out this evaluation by means of a method that takes into account the superficial nature of the DEM and, therefore, its sampling is superficial and not punctual. This work is part of the Research Project "Functional Quality of Digital Elevation Models in Engineering" where it is necessary to control the quality of a DEM whose data source is an experimental LiDAR flight with a density of 14 points per square meter to which we call Point Cloud Product (PCpro). In the present work it is described the capture data on the ground and the postprocessing tasks until getting the point cloud that will be used as reference (PCref) to evaluate the PCpro quality. Each PCref consists of a patch 50x50 m size coming from a registration of 4 different scan stations. The area studied was the Spanish region of Navarra that covers an area of 10,391 km2; 30 patches homogeneously distributed were necessary to sample the entire surface. The patches have been captured using a Leica BLK360 terrestrial laser scanner mounted on a pole that reached heights of up to 7 meters; the position of the scanner was inverted so that the characteristic shadow circle does not exist when the scanner is in direct position. To ensure that the accuracy of the PCref is greater than that of the PCpro, the georeferencing of the PCref has been carried out with real-time GNSS, and its accuracy positioning was better than 4 cm; this accuracy is much better than the altimetric mean square error estimated for the PCpro (<15 cm); The kind of DEM of interest is the corresponding to the bare earth, so that it was necessary to apply a filter to eliminate vegetation and auxiliary elements such as poles, tripods, etc. After the postprocessing tasks the PCref is ready to be compared with the PCpro using different techniques: cloud to cloud or after a resampling process DEM to DEM.

Keywords: data quality, DEM, LiDAR, terrestrial laser scanner, accuracy

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Authors: Tomoko Fukuyama, Osamu Senbu

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Prestressed concrete is used a lot in infrastructures such as roads or bridges. However, poor grout filling and PC steel corrosion are currently major issues of prestressed concrete structures. One of the problems with nondestructive corrosion detection of PC steel is a plastic pipe which covers PC steel. The insulative property of pipe makes a nondestructive diagnosis difficult; therefore a practical technology to detect these defects is necessary for the maintenance of infrastructures. The goal of the research is a development of an electrochemical technique which enables to detect internal defects from the surface of prestressed concrete nondestructively. Ideally, the measurements should be conducted from the surface of structural members to diagnose non-destructively. In the present experiment, a prestressed concrete member is simplified as a layered specimen to simulate a current path between an input and an output electrode on a member surface. The specimens which are layered by mortar and the prestressed concrete constitution materials (steel, polyethylene, stainless steel, or galvanized steel plates) were provided to the alternating current impedance measurement. The magnitude of an applied electric field was 0.01-volt or 1-volt, and the frequency range was from 106 Hz to 10-2 Hz. The frequency spectrums of impedance, which relate to charge reactions activated by an electric field, were measured to clarify the effects of the material configurations or the properties. In the civil engineering field, the Nyquist diagram is popular to analyze impedance and it is a good way to grasp electric relaxation using a shape of the plot. However, it is slightly not suitable to figure out an influence of a measurement frequency which is reciprocal of reaction time. Hence, Bode diagram is also applied to describe charge reactions in the present paper. From the experiment results, the alternating current impedance method looks to be applicable to the insulative material measurement and eventually prestressed concrete diagnosis. At the same time, the frequency spectrums of impedance show the difference of the material configuration. This is because the charge mobility reflects the variety of substances and also the measuring frequency of the electric field determines migration length of charges which are under the influence of the electric field. However, it could not distinguish the differences of the material thickness and is inferred the difficulties of prestressed concrete diagnosis to identify the amount of an air void or a layer of corrosion product by the technique.

Keywords: capacitance, conductance, prestressed concrete, susceptance

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Authors: Naif Mohsen Alharbi

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This paper present failure occurred on flexible coupling installed at oil anf gas operation. Also it presents maintenance ideas implemented on the flexible coupling installed to transmit high torque from gearbox to pump. Basically, the machine train is including steam turbine which drives the pump and there is gearbox located in between for speed reduction. investigation are identifying the root causes, solving and developing the technology designs or bad actor. This report provides the study intentionally for continues operation optimization, utilize the advanced opportunity and implement a improvement. Objective: The main objectives of the investigation are identifying the root causes, solving and developing the technology designs or bad actor. Ultimately, fulfilling the operation productivity, also ensuring better technology, quality and design by solutions. This report provides the study intentionally for continues operation optimization, utilize the advanced opportunity and implemet improvement. Method: The method used in this project was a very focused root cause analysis procedure that incorporated engineering analysis and measurements. The analysis method extensively covers the measuring of the complete coupling dimensions. Including the membranes thickness, hubs, bore diameter and total length, dismantle flexible coupling to diagnose how deep the coupling has been affected. Also, defining failure modes, so that the causes could be identified and verified. Moreover, Vibration analysis and metallurgy test. Lastly applying several solutions by advanced tools (will be mentioned in detail). Results and observation: Design capacity: Coupling capacity is an inadequate to fulfil 100% of operating conditions. Therefore, design modification of service factor to be at least 2.07 is crucial to address this issue and prevent recurrence of similar scenario, especially for the new upgrading project. Discharge fluctuation: High torque flexible coupling encountered during the operation. Therefore, discharge valve behaviour, tuning, set point and general conditions revaluated and modified subsequently, it can be used as baseline for upcoming Coupling design project. Metallurgy test: Material of flexible coupling membrane (discs) tested at the lab, for a detailed metallurgical investigation, better material grade has been selected for our operating conditions,

Keywords: high speed machine, reliabilty, flexible coupling, rotating equipment

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Authors: B. S Kaith, K. Sharma, V. Kumar, S. Kalia

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Superabsorbent are three-dimensional networks of linear or branched polymeric chains which can uptake large volume of biological fluids. The ability is due to the presence of functional groups like –NH2, -COOH and –OH. Such cross-linked products based on natural materials, such as cellulose, starch, dextran, gum and chitosan, because of their easy availability, low production cost, non-toxicity and biodegradability have attracted the attention of Scientists and Technologists all over the world. Since natural polymers have better biocompatibility and are non-toxic than most synthetic one, therefore, such materials can be applied in the preparation of controlled drug delivery devices, biosensors, tissue engineering, contact lenses, soil conditioning, removal of heavy metal ions and dyes. Gums are natural potential antioxidants and are used as food additives. They have excellent properties like high solubility, pH stability, non-toxicity and gelling characteristics. Till date lot of methods have been applied for the synthesis and modifications of cross-linked materials with improved properties suitable for different applications. It is well known that ion beam irradiation can play a crucial role to synthesize, modify, crosslink or degrade polymeric materials. High energetic heavy ions irradiation on polymer film induces significant changes like chain scission, cross-linking, structural changes, amorphization and degradation in bulk. Various researchers reported the effects of low and heavy ion irradiation on the properties of polymeric materials and observed significant improvement in optical, electrical, chemical, thermal and dielectric properties. Moreover, modifications induced in the materials mainly depend on the structure, the ion beam parameters like energy, linear energy transfer, fluence, mass, charge and the nature of the target material. Ion-beam irradiation is a useful technique for improving the surface properties of biodegradable polymers without missing the bulk properties. Therefore, a considerable interest has been grown to study the effects of SHIs irradiation on the properties of synthesized semi-IPNs and IPNs. The present work deals with the preparation of semi-IPNs and IPNs and impact of SHI like O7+ and Ni9+ irradiation on optical, chemical, structural, morphological and thermal properties along with impact on different applications. The results have been discussed on the basis of Linear Energy Transfer (LET) of the ions.

Keywords: adsorbent, gel, IPNs, semi-IPNs

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Authors: Masoud Sakhinia, Sajjad Ahmad

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Introduction: Though knowledge of the compositional makeup and structure of the limbal niche has progressed exponentially during the past decade, much is yet to be understood. Identifying the precise profile and role of the stromal makeup which spans the ocular surface may inform researchers of the most optimum conditions needed to effectively expand LESCs in vitro, whilst preserving their differentiation status and phenotype. Limbal fibroblasts, as opposed to corneal fibroblasts are thought to form an important component of the microenvironment where LESCs reside. Methods: The corneal stroma was tissue engineered in vitro using both limbal and corneal fibroblasts embedded within a tissue engineered 3D collagen matrix. The effect of these two different fibroblasts on LESCs and hTCEpi corneal epithelial cell line were then subsequently determined using phase contrast microscopy, histolological analysis and PCR for specific stem cell markers. The study aimed to develop an in vitro model which could be used to determine whether limbal, as opposed to corneal fibroblasts, maintained the stem cell phenotype of LESCs and hTCEpi cell line. Results: Tissue culture analysis was inconclusive and required further quantitative analysis for remarks on cell proliferation within the varying stroma. Histological analysis of the tissue-engineered cornea showed a comparable structure to that of the human cornea, though with limited epithelial stratification. PCR results for epithelial cell markers of cells cultured on limbal fibroblasts showed reduced expression of CK3, a negative marker for LESC’s, whilst also exhibiting a relatively low expression level of P63, a marker for undifferentiated LESCs. Conclusion: We have shown the potential for the construction of a tissue engineered human cornea using a 3D collagen matrix and described some preliminary results in the analysis of the effects of varying stroma consisting of limbal and corneal fibroblasts, respectively, on the proliferation of stem cell phenotype of primary LESCs and hTCEpi corneal epithelial cells. Although no definitive marker exists to conclusively illustrate the presence of LESCs, the combination of positive and negative stem cell markers in our study were inconclusive. Though it is less traslational to the human corneal model, the use of conditioned medium from that of limbal and corneal fibroblasts may provide a more simple avenue. Moreover, combinations of extracellular matrices could be used as a surrogate in these culture models.

Keywords: cornea, Limbal Stem Cells, tissue engineering, PCR

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Authors: Sushil Pradhan

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Biotechnology contributes to sustainable development in several ways such as biofertilizer production, biopesticide production and management of environmental pollution, tissue culture and biodiversity conservation in vitro, in vivo and in situ, Insectivorous medicinal plant Drosera burmannii Vahl belongs to the Family-Droseraceae under Order-Caryophyllales, Dicotyledoneae, Angiospermeae which has 31 (thirty one) living genera and 194 species besides 7 (seven) extinct (fossil) genera. Locally it is known as “Patkanduri” in Odia. Its Hindi name is “Mukhajali” and its English name is “Sundew”. The earliest species of Drosera was first reported in 1753 by Carolous Linnaeus called Drosera indica L (Indian Sundew). The latest species of Drosera reported by Fleisch A, Robinson, AS, McPherson S, Heinrich V, Gironella E and Madulida D.A. (2011) is Drosera ultramafica from Malaysia. More than 50 % species of Drosera have been reported from Australia and next to Australia is South Africa. India harbours only 3 species such as D. indica L, Drosera burmannii Vahl and D. peltata L. From our Odisha only D. burmannii Vahl is being reported for the first time from the district of Subarnapur near Sonepur (Arjunpur Reserve Forest Area). Drosera plant is autotrophic but to supplement its Nitrogen (N2) requirement it adopts heterotrophic mode of nutrition (insectivorous/carnivorous) as well. The colour of plant in mostly red and about 20-30cm in height with beautiful pink or white pentamerous flowers. Plants grow luxuriantly during November to February in shady and moist places near small water bodies of running water stream. Medicinally it is a popular herb in the locality for the treatment of cold and cough in children in rainy season by the local Doctors (Kabiraj and Baidya). In the present field investigation an attempt has been made to understand the unique reproductive phase and life cycle of the plant thereby planning for its conservation and propagation through various techniques of tissue culture and biotechnology. More importantly besides morphological and anatomical studies, cytological investigation is being carried out to find out the number of chromosomes in the cell and its genomics as there is no such report as yet for Drosera burmannii Vahl. The ecological significance and biodiversity conservation of Drosera with special reference to energy, environmental and chemical engineering has been discussed in the research paper presentation.

Keywords: insectivorous, medicinal, drosera, biotechnology, chromosome, genome

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Authors: Ajay Mandal, Jitendar Kumar Tiwari, N. Sathish, A. K. Srivastava

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A fundamental investigation is performed on the development of graphene (Gr) reinforced stainless steel 316L (SS 316L) metal matrix composite via selective laser melting (SLM) in order to improve specific strength and wear resistance property of SS 316L. Firstly, SS 316L powder and graphene were mixed in a fixed ratio using low energy planetary ball milling. The milled powder is then subjected to the SLM process to fabricate composite samples at a laser power of 320 W and exposure time of 100 µs. The prepared composite was mechanically tested (hardness and tensile test) at ambient temperature, and obtained results indicate that the properties of the composite increased significantly with the addition of 0.2 wt. % Gr. Increment of about 25% (from 194 to 242 HV) and 70% (from 502 to 850 MPa) is obtained in hardness and yield strength of composite, respectively. Raman mapping and XRD were performed to see the distribution of Gr in the matrix and its effect on the formation of carbide, respectively. Results of Raman mapping show the uniform distribution of graphene inside the matrix. Electron back scatter diffraction (EBSD) map of the prepared composite was analyzed under FESEM in order to understand the microstructure and grain orientation. Due to thermal gradient, elongated grains were observed along the building direction, and grains get finer with the addition of Gr. Most of the mechanical components are subjected to several types of wear conditions. Therefore, it is very necessary to improve the wear property of the component, and hence apart from strength and hardness, a tribological property of composite was also measured under dry sliding condition. Solid lubrication property of Gr plays an important role during the sliding process due to which the wear rate of composite reduces up to 58%. Also, the surface roughness of worn surface reduces up to 70% as measured by 3D surface profilometry. Finally, it can be concluded that SLM is an efficient method of fabricating cutting edge metal matrix nano-composite having Gr like reinforcement, which was very difficult to fabricate through conventional manufacturing techniques. Prepared composite has superior mechanical and tribological properties and can be used for a wide variety of engineering applications. However, due to the unavailability of a considerable amount of literature in a similar domain, more experimental works need to perform, such as thermal property analysis, and is a part of ongoing study.

Keywords: selective laser melting, graphene, composite, mechanical property, tribological property

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Authors: Franco Primo Soffietti, Diego Fernando Turello, Federico Pinto

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Shear waves that propagate through the ground impose deformations that must be taken into account in the design and assessment of buried longitudinal structures such as tunnels, pipelines, and piles. Conventional engineering approaches for seismic evaluation often rely on a Euler-Bernoulli beam models supported by a Winkler foundation. This approach, however, falls short in capturing the distortions induced when the structure is subjected to shear waves. To overcome these limitations, in the present work an analytical solution is proposed considering a Timoshenko beam and including transverse and rotational springs. The present research proposes ground springs derived as closed-form analytical solutions of the equations of elasticity including the seismic wavelength. These proposed springs extend the applicability of previous plane-strain models. By considering variations in displacements along the longitudinal direction, the presented approach ensures the springs do not approach zero at low frequencies. This characteristic makes them suitable for assessing pseudo-static cases, which typically govern structural forces in kinematic interaction analyses. The results obtained, validated against existing literature and a 3D Finite Element model, reveal several key insights: i) the cutoff frequency significantly influences transverse and rotational springs; ii) neglecting displacement variations along the structure axis (i.e., assuming plane-strain deformation) results in unrealistically low transverse springs, particularly for wavelengths shorter than the structure length; iii) disregarding lateral displacement components in rotational springs and neglecting variations along the structure axis leads to inaccurately low spring values, misrepresenting interaction phenomena; iv) transverse springs exhibit a notable drop in resonance frequency, followed by increasing damping as frequency rises; v) rotational springs show minor frequency-dependent variations, with radiation damping occurring beyond resonance frequencies, starting from negative values. This comprehensive analysis sheds light on the complex behavior of embedded longitudinal structures when subjected to shear waves and provides valuable insights for the seismic assessment.

Keywords: shear waves, Timoshenko beams, Winkler springs, sol-structure interaction

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Authors: Kulin Dave, Kapil Mohan

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Earthquakes are considered to be the most destructive rapid-onset disasters human beings are exposed to. The amount of loss it brings in is sufficient to take careful considerations for designing of structures and facilities. Seismic Hazard Analysis is one such tool which can be used for earthquake resistant design. Ground Response Analysis is one of the most crucial and decisive steps for seismic hazard analysis. Rapar district of Kutch, Gujarat falls in Zone 5 of earthquake zone map of India and thus has high seismicity because of which it is selected for analysis. In total 8 bore-log data were studied at different locations in and around Rapar district. Different soil engineering properties were analyzed and relevant empirical correlations were used to calculate maximum shear modulus (Gmax) and shear wave velocity (Vs) for the soil layers. The soil was modeled using Pressure-Dependent Modified Kodner Zelasko (MKZ) model and the reference curve used for fitting was Seed and Idriss (1970) for sand and Darendeli (2001) for clay. Both Equivalent linear (EL), as well as Non-linear (NL) ground response analysis, has been carried out with Masing Hysteretic Re/Unloading formulation for comparison. Commercially available DEEPSOIL v. 7.0 software is used for this analysis. In this study an attempt is made to quantify ground response regarding generated acceleration time-history at top of the soil column, Response spectra calculation at 5 % damping and Fourier amplitude spectrum calculation. Moreover, the variation of Peak Ground Acceleration (PGA), Maximum Displacement, Maximum Strain (in %), Maximum Stress Ratio, Mobilized Shear Stress with depth is also calculated. From the study, PGA values estimated in rocky strata are nearly same as bedrock motion and marginal amplification is observed in sandy silt and silty clays by both analyses. The NL analysis gives conservative results of maximum displacement as compared to EL analysis. Maximum strain predicted by both studies is very close to each other. And overall NL analysis is more efficient and realistic because it follows the actual hyperbolic stress-strain relationship, considers stiffness degradation and mobilizes stresses generated due to pore water pressure.

Keywords: DEEPSOIL v 7.0, ground response analysis, pressure-dependent modified Kodner Zelasko model, MKZ model, response spectra, shear wave velocity

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Authors: Christoph Hacker, Zeynep Karahaliloglu, Gunnar Seide, Emir Baki Denkbas, Thomas Gries

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A wound dressing material is designed to facilitate wound healing and minimize scarring. An ideal wound dressing material should protect the wound from any contaminations of exogeneous microorganism. In addition, the dressing material should provide a moist environment through extraction of body fluid from the wound area. Recently, wound dressing electrospun nanofibrous membranes are produced by electrospinning from a polymer solution or a polymer melt. These materials have a great potential as dressing materials for wound healing because of superior properties such as high surface-to-volume ratio, high porosity with excellent pore interconnectivity. Melt electrospinning is an attractive tissue engineering scaffold manufacturing process which eliminated the health risk posed by organic solvents used in electrospinning process and reduced the production costs. In this study, antibacterial wound dressing materials were prepared from TPU (Elastollan 1185A) by a melt-electrospinning technique. The electrospinning parameters for an efficient melt-electrospinning process of TPU were optimized. The surface of the fibers was modified with poly(ethylene glycol) (PEG) by radio-frequency glow discharge plasma deposition method and with silver nanoparticles (nAg) to improve their wettability and antimicrobial properties. TPU melt-electrospun mats were characterized using SEM, DSC, TGA and XPS. The cell viability and proliferation on modified melt-electrospun TPU mats were evaluated using a mouse fibroblast cell line (L929). Antibacterial effects of theirs against both Staphylococcus aureus strain and Escherichia coli were investigated by disk-diffusion method. TPU was successfully processed into a porous, fibrous network of beadless fibers in the micrometer range (4.896±0.94 µm) with a voltage of 50 kV, a working distance of 6 cm, a temperature of the thermocouple and hot coil of 225–230ºC, and a flow rate of 0.1 mL/h. The antibacterial test indicated that PEG-modified nAg-loaded TPU melt-electrospun structure had excellent antibacterial effects and cell study results demonstrated that nAg-loaded TPU mats had no cytotoxic effect on the fibroblast cells. In this work, the surface of a melt-electrospun TPU mats was modified via PEG monomer and then nAg. Results showed melt-electrospun TPU mats modified with PEG and nAg have a great potential for use as an antibacterial wound dressing material and thus, requires further investigation.

Keywords: melt electrospinning, nanofiber, silver nanoparticles, wound dressing

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Authors: Matthew J. Emes, Azadeh Jafari, Maziar Arjomandi

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Velocity fluctuations of shear-generated turbulence are largest in the atmospheric surface layer (ASL) of nominal 100 m depth, which can lead to dynamic effects such as galloping and flutter on small physical structures on the ground when the turbulence length scales and characteristic length of the physical structure are the same order of magnitude. Turbulence length scales are a measure of the average sizes of the energy-containing eddies that are widely estimated using two-point cross-correlation analysis to convert the temporal lag to a separation distance using Taylor’s hypothesis that the convection velocity is equal to the mean velocity at the corresponding height. Profiles of turbulence length scales in the neutrally-stratified ASL, as predicted by Monin-Obukhov similarity theory in Engineering Sciences Data Unit (ESDU) 85020 for single-point data and ESDU 86010 for two-point correlations, are largely dependent on the aerodynamic roughness length. Field measurements have shown that longitudinal turbulence length scales show significant regional variation, whereas length scales of the vertical component show consistent Obukhov scaling from site to site because of the absence of low-frequency components. Hence, the objective of this experimental study is to compare the similarity theory relationships between the turbulence length scales and aerodynamic roughness length with those calculated using the autocorrelations and cross-correlations of field measurement velocity data at two sites: the Surface Layer Turbulence and Environmental Science Test (SLTEST) facility in a desert ASL in Dugway, Utah, USA and the Commonwealth Scientific and Industrial Research Organisation (CSIRO) wind tower in a rural ASL in Jemalong, NSW, Australia. The results indicate that the longitudinal turbulence length scales increase with increasing aerodynamic roughness length, as opposed to the relationships derived by similarity theory correlations in ESDU models. However, the ratio of the turbulence length scales in the lateral and vertical directions to the longitudinal length scales is relatively independent of surface roughness, showing consistent inner-scaling between the two sites and the ESDU correlations. Further, the diurnal variation of wind velocity due to changes in atmospheric stability conditions has a significant effect on the turbulence structure of the energy-containing eddies in the lower ASL.

Keywords: aerodynamic roughness length, atmospheric surface layer, similarity theory, turbulence length scales

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Authors: Rui Teixeira, Alan O’Connor, Maria Nogal

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The statistical theory of extreme events is progressively a topic of growing interest in all the fields of science and engineering. The changes currently experienced by the world, economic and environmental, emphasized the importance of dealing with extreme occurrences with improved accuracy. When it comes to the design of offshore structures, particularly offshore wind turbines, the importance of efficiently characterizing extreme events is of major relevance. Extreme events are commonly characterized by extreme values theory. As an alternative, the accurate modeling of the tails of statistical distributions and the characterization of the low occurrence events can be achieved with the application of the Peak-Over-Threshold (POT) methodology. The POT methodology allows for a more refined fit of the statistical distribution by truncating the data with a minimum value of a predefined threshold u. For mathematically approximating the tail of the empirical statistical distribution the Generalised Pareto is widely used. Although, in the case of the exceedances of significant wave data (H_s) the 2 parameters Weibull and the Exponential distribution, which is a specific case of the Generalised Pareto distribution, are frequently used as an alternative. The Generalized Pareto, despite the existence of practical cases where it is applied, is not completely recognized as the adequate solution to model exceedances over a certain threshold u. References that set the Generalised Pareto distribution as a secondary solution in the case of significant wave data can be identified in the literature. In this framework, the current study intends to tackle the discussion of the application of statistical models to characterize exceedances of wave data. Comparison of the application of the Generalised Pareto, the 2 parameters Weibull and the Exponential distribution are presented for different values of the threshold u. Real wave data obtained in four buoys along the Irish coast was used in the comparative analysis. Results show that the application of the statistical distributions to characterize significant wave data needs to be addressed carefully and in each particular case one of the statistical models mentioned fits better the data than the others. Depending on the value of the threshold u different results are obtained. Other variables of the fit, as the number of points and the estimation of the model parameters, are analyzed and the respective conclusions were drawn. Some guidelines on the application of the POT method are presented. Modeling the tail of the distributions shows to be, for the present case, a highly non-linear task and, due to its growing importance, should be addressed carefully for an efficient estimation of very low occurrence events.

Keywords: extreme events, offshore structures, peak-over-threshold, significant wave data

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Authors: Kamran Jawed, Anu Jose Mattam, Zia Fatma, Saima Wajid, Malik Z. Abdin, Syed Shams Yazdani

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Worldwide demand of natural and sustainable fuels and chemicals have encouraged researchers to develop microbial platform for synthesis of short chain fatty acids as they are useful precursors to replace petroleum-based fuels and chemicals. In this study, we evaluated the role of fatty acid synthesis and β-oxidation cycle of Escherichia coli to produce butyric acid, a 4-carbon short chain fatty acid, with the help of three thioesterases, i.e., TesAT from Anaerococcus tetradius, TesBF from Bryantella formatexigens and TesBT from Bacteroides thetaiotaomicron. We found that E. coli strain transformed with gene for TesBT and grown in presence of 8 g/L glucose produced maximum butyric acid titer at 1.46 g/L, followed by that of TesBF at 0.85 g/L and TesAT at 0.12 g/L, indicating that these thioesterases were efficiently converting short chain fatty acyl-ACP intermediate of fatty acid synthesis pathway into the corresponding acid. The titer of butyric acid varied significantly depending upon the plasmid copy number and strain genotype. Deletion of genes for fatty acyl-CoA synthetase and acyl-CoA dehydrogenase, which are involved in initiating the fatty acid degradation cycle, and overexpression of FadR, which is a dual transcriptional regulator and exerts negative control over fatty acid degradation pathway, reduced up to 30% of butyric acid titer. This observation suggested that β-oxidation pathway is working synergistically with fatty acid synthesis pathway in production of butyric acid. Moreover, accelerating the fatty acid elongation cycle by overexpressing acetyl-CoA carboxyltransferase (Acc) and 3-hydroxy-acyl-ACP dehydratase (FabZ) or by deleting FabR, the transcription suppressor of elongation, did not improve the butyric acid titer, rather favored the long chain fatty acid production. Finally, a balance between cell growth and butyric acid production was achieved with the use of phosphorous limited growth medium and 14.3 g/L butyric acid, and 17.5 g/L total free fatty acids (FFAs) titer was achieved during fed-batch cultivation. We have engineered an E. coli strain which utilizes the intermediate of both fatty acid synthesis and degradation pathway, i.e. butyryl-ACP and -CoA, to produce butyric acid from glucose. The strategy used in this study resulted in highest reported titers of butyric acid and FFAs in engineered E. coli.

Keywords: butenoic acid, butyric acid, Escherichia coli, fed-batch fermentation, short chain fatty acids, thioesterase

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Authors: Fatemeh Elmi, Zahra Etemadifar

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Improvement of soil mechanical properties is crucial before its use in construction, as the low mechanical strength and unstable structure of soil in many parts of the world can lead to the destruction of engineering infrastructure, resulting in financial and human losses. Although, conventional methods, such as chemical injection, are often utilized to enhance soil strength and stiffness, they are generally expensive, require heavy machinery, and cause significant environmental effects due to chemical usage, and also disrupt urban infrastructure. Moreover, they are not suitable for treating large volume of soil. Recently, an alternative method to improve various soil properties, including strength, hardness, and permeability, has received much attention: the application of biological methods. One of the most widely used is biocementation, which is based on the microbial precipitation of calcium carbonte crystalls using ureolytic bacteria However, there are still limitations to its large-scale use that need to be resolved before it can be commercialized. These issues have not received enough attention in prior research. One limitation of MICP (microbially induced calcium carbonate precipitation) is that microorganisms cannot operate effectively in harsh and variable environments, unlike the controlled conditions of a laboratory. Another limitation of applying this technique on a large scale is the high cost of producing a substantial amount of bacterial culture and reagents required for soil treatment. Therefore, the purpose of the present study was to investigate soil improvement using the biocementation activity of poly-extremophile, calcium carbonate crystal- producing bacterial strain, Bhargavaea cecembensis N1, in whey as an inexpensive medium. This strain was isolated and molecularly identified from sandy soils in our previous research, and its 16S rRNA gene sequences was deposited in the NCBI Gene Bank with an accession number MK420385. This strain exhibited a high level of urease activity (8.16 U/ml) and produced a large amount of calcium carbonate (4.1 mg/ ml). It was able to improve the soil by increasing the compressive strength up to 205 kPa and reducing permeability by 36%, with 20% of the improvement attributable of calcium carbonate production. This was achieved using this strain in a whey culture medium. This strain can be an eco-friendly and economical alternative to conventional methods in soil stabilization, and other MICP related applications.

Keywords: biocementation, Bhargavaea cecembensis, soil improvement, whey culture medium

Procedia PDF Downloads 36

Authors: Mohammad Khoshini, Arman Khoshghalb, Meghdad Payan, Nasser Khalili

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Most of the Earth’s crust surface rocks are technically categorized as weak rocks or weakly bonded geomaterials. Deeply weathered, weakly cemented, friable and easily erodible, they demonstrate complex material behaviour and understanding the overlooked mechanical behaviour of such materials is of particular importance in geotechnical engineering practice. Weakly bonded geomaterials are so susceptible to surface shear and moisture that conventional methods of core drilling fail to extract high-quality undisturbed samples out of them. Moreover, most of these geomaterials are of high heterogeneity rendering less reliable and feasible material characterization. In order to compensate for the unpredictability of the material response, either numerous experiments are needed to be conducted or large factors of safety must be implemented in the design process. However, none of these approaches is sustainable. In this study, a method for dry core drilling of such materials is introduced to take high-quality undisturbed core samples. By freezing the material at certain moisture content, a secondary structure is developed throughout the material which helps the whole structure to remain intact during the core drilling process. Moreover, to address the heterogeneity issue, the natural material was reconstructed artificially to obtain a homogeneous material with very high similarity to the natural one in both micro and macro-mechanical perspectives. The method is verified for both micro and macro scale. In terms of micro-scale analysis, using Scanning Electron Microscopy (SEM), pore spaces and inter-particle bonds were investigated and compared between natural and artificial materials. X-Ray Diffraction, XRD, analyses are also performed to control the chemical composition. At the macro scale, several uniaxial compressive strength tests, as well as triaxial tests, were performed to verify the similar mechanical response of the materials. A high level of agreement is observed between micro and macro results of natural and artificially bonded geomaterials. The proposed methods can play an important role to cut down the costs of experimental programs for material characterization and also to promote the accuracy of the numerical modellings based on the experimental results.

Keywords: Artificial geomaterial, core drilling, macro-mechanical behavior, micro-scale, sample preparation, SEM photography, weakly bonded geomaterials

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Authors: K. Thiel, P. Patrikainen, C. Nagy, D. Fitzpatrick, E.-M. Aro, P. Kallio

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Photosynthetic cyanobacteria have been recognized as potential future biotechnological hosts for the direct conversion of CO₂ into chemicals of interest using sunlight as the solar energy source. However, in order to develop commercially viable systems, the flux of electrons from the photosynthetic light reactions towards specified target chemicals must be significantly improved. The objective of the study was to investigate whether the autotrophic production efficiency of specified end-metabolites can be improved in engineered cyanobacterial cells by rescuing excited electrons that are normally lost to molecular oxygen due to the cyanobacterial flavodiiron protein Flv1/3. Natively Flv1/3 dissipates excess electrons in the photosynthetic electron transfer chain by directing them to molecular oxygen in Mehler-like reaction to protect photosystem I. To evaluate the effect of flavodiiron inactivation on autotrophic production efficiency in the cyanobacterial host Synechocystis sp. PCC 6803 (Synechocystis), sucrose was selected as the quantitative reporter and a representative of a potential end-product of interest. The concept is based on the native property of Synechocystis to produce sucrose as an intracellular osmoprotectant when exposed to high external ion concentrations, in combination with the introduction of a heterologous sucrose permease (CscB from Escherichia coli), which transports the sucrose out from the cell. In addition, cell growth, photosynthetic gas fluxes using membrane inlet mass spectrometry and endogenous storage compounds were analysed to illustrate the consequent effects of flv deletion on pathway flux distributions. The results indicate that a significant proportion of the electrons can be lost to molecular oxygen via Flv1/3 even when the cells are grown under high CO₂ and that the inactivation of flavodiiron activity can enhance the photosynthetic electron flux towards optionally available sinks. The flux distribution is dependent on the light conditions and the genetic context of the Δflv mutants, and favors the production of either sucrose or one of the two storage compounds, glycogen or polyhydroxybutyrate. As a conclusion, elimination of the native Flv1/3 reaction and concomitant introduction of an engineered product pathway as an alternative sink for excited electrons could enhance the photosynthetic electron flux towards the target endproduct without compromising the fitness of the host.

Keywords: cyanobacterial engineering, flavodiiron proteins, redirecting electron flux, sucrose

Procedia PDF Downloads 109

Authors: Azieva A. M., Yastremsky E. V., Kirillova D. A., Patsaev T. D., Sharikov R. V., Kamyshinsky R. A., Lukanina K. I., Sharikova N. A., Grigoriev T. E., Vasiliev A. L.

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Adhesive properties of scaffolds, which predominantly depend on the chemical and structural features of their surface, play the most important role in tissue engineering. The basic requirements for such scaffolds are biocompatibility, biodegradation, high cell adhesion, which promotes cell proliferation and differentiation. In many cases, synthetic polymers scaffolds have proven advantageous because they are easy to shape, they are tough, and they have high tensile properties. The regeneration of nerve tissue still remains a big challenge for medicine, and neural stem cells provide promising therapeutic potential for cell replacement therapy. However, experiments with stem cells have their limitations, such as low level of cell viability and poor control of cell differentiation. Whereas the study of already differentiated neuronal cell culture obtained from newborn mouse brain is limited only to cell adhesion. The growth and implantation of neuronal culture requires proper scaffolds. Moreover, the polymer scaffolds implants with neuronal cells could demand specific morphology. To date, it has been proposed to use numerous synthetic polymers for these purposes, including polystyrene, polylactic acid (PLA), polyglycolic acid, and polylactide-glycolic acid. Tissue regeneration experiments demonstrated good biocompatibility of PLA scaffolds, despite the hydrophobic nature of the compound. Problem with poor wettability of the PLA scaffold surface could be overcome in several ways: the surface can be pre-treated by poly-D-lysine or polyethyleneimine peptides; roughness and hydrophilicity of PLA surface could be increased by plasma treatment, or PLA could be combined with natural fibers, such as collagen or chitosan. This work presents a study of adhesion of both induced pluripotent stem cells (iPSCs) and mouse primary neuronal cell culture on the polylactide scaffolds of various types: oriented and non-oriented fibrous nonwoven materials and sponges – with and without the effect of plasma treatment and composites with collagen and chitosan. To evaluate the effect of different types of PLA scaffolds on the neuronal differentiation of iPSCs, we assess the expression of NeuN in differentiated cells through immunostaining. iPSCs more effectively differentiate into neurons on PLA scaffolds with high adhesive properties for primary neuronal cells.

Keywords: PLA scaffold, neurons, neuronal differentiation, stem cells, polylactid

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Authors: Takashi Mitsuishi

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Fuzzy logic has gained acceptance in the recent years in the fields of social sciences and humanities such as psychology and linguistics because it can manage the fuzziness of words and human subjectivity in a logical manner. However, the major field of application of the fuzzy logic is control engineering as it is a part of the set theory and mathematical logic. Mamdani method, which is the most popular technique for approximate reasoning in the field of fuzzy control, is one of the ways to numerically represent the control afforded by human language and sensitivity and has been applied in various practical control plants. Fuzzy logic has been gradually developing as an artificial intelligence in different applications such as neural networks, expert systems, and operations research. The objects of inference vary for different application fields. Some of these include time, angle, color, symptom and medical condition whose fuzzy membership function is a periodic function. In the defuzzification stage, the domain of the membership function should be unique to obtain uniqueness its defuzzified value. However, if the domain of the periodic membership function is determined as unique, an unintuitive defuzzified value may be obtained as the inference result using the center of gravity method. Therefore, the authors propose a method of circular-polar-coordinates transformation and defuzzification of the periodic membership functions in this study. The transformation to circular polar coordinates simplifies the domain of the periodic membership function. Defuzzified value in circular polar coordinates is an argument. Furthermore, it is required that the argument is calculated from a closed plane figure which is a periodic membership function on the circular polar coordinates. If the closed plane figure is continuous with the continuity of the membership function, a significant amount of computation is required. Therefore, to simplify the practice example and significantly reduce the computational complexity, we have discretized the continuous interval and the membership function in this study. In this study, the following three methods are proposed to decide the argument from the discrete polygon which the continuous plane figure is transformed into. The first method provides an argument of a straight line passing through the origin and through the coordinate of the arithmetic mean of each coordinate of the polygon (physical center of gravity). The second one provides an argument of a straight line passing through the origin and the coordinate of the geometric center of gravity of the polygon. The third one provides an argument of a straight line passing through the origin bisecting the perimeter of the polygon (or the closed continuous plane figure).

Keywords: defuzzification, fuzzy membership function, periodic function, polar coordinates transformation

Procedia PDF Downloads 341

Authors: Iddy Iddy, Qin Jiang, Changkuan Zhang

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This paper addresses the hydraulic performance of curtain wall breakwaters as a coastal structure protection based on the particles method modelling. The hydraulic functions of curtain wall as wave barriers by reflecting large parts of incident waves through the vertical wall, a part transmitted and a particular part was dissipating the wave energies through the eddy flows formed beneath the lower end of the plate. As a Lagrangian particle, the Moving Particle Semi-implicit (MPS) method which has a robust capability for numerical representation has proven useful for design of structures application that concern free-surface hydrodynamic flow, such as wave breaking and overtopping. In this study, a vertical two-dimensional numerical model for the simulation of violent flow associated with the interaction between the curtain-wall breakwaters and progressive water waves is developed by MPS method in which a higher precision pressure gradient model and free surface particle recognition model were proposed. The wave transmission, reflection, and energy dissipation of the vertical wall were experimentally and theoretically examined. With the numerical wave flume by particle method, very detailed velocity and pressure fields around the curtain-walls under the action of waves can be computed in each calculation steps, and the effect of different wave and structural parameters on the hydrodynamic characteristics was investigated. Also, the simulated results of temporal profiles and distributions of velocity and pressure in the vicinity of curtain-wall breakwaters are compared with the experimental data. Herein, the numerical investigation of hydraulic performance of curtain wall breakwaters indicated that the incident wave is largely reflected from the structure, while the large eddies or turbulent flows occur beneath the curtain-wall resulting in big energy losses. The improved MPS method shows a good agreement between numerical results and analytical/experimental data which are compared to related researches. It is thus verified that the improved pressure gradient model and free surface particle recognition methods are useful for enhancement of stability and accuracy of MPS model for water waves and marine structures. Therefore, it is possible for particle method (MPS method) to achieve an appropriate level of correctness to be applied in engineering fields through further study.

Keywords: curtain wall breakwaters, free surface flow, hydraulic performance, improved MPS method

Procedia PDF Downloads 135

Authors: Emiliano Matta

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Passive resonant vibration absorbers are among the most widely used dynamic control systems in civil engineering. They typically consist in a single-degree-of-freedom mechanical appendage of the main structure, tuned to one structural target mode through frequency and damping optimization. One classical scheme is the pendulum absorber, whose mass is constrained to move along a curved trajectory and is damped by viscous dashpots. Even though the principle is well known, the search for improved arrangements is still under way. In recent years this investigation inspired a type of bidirectional pendulum absorber (BPA), consisting of a mass constrained to move along an optimal three-dimensional (3D) concave surface. For such a BPA, the surface principal curvatures are designed to ensure a bidirectional tuning of the absorber to both principal modes of the main structure, while damping is produced either by horizontal viscous dashpots or by vertical friction dashpots, connecting the BPA to the main structure. In this paper, a variant of BPA is proposed, where damping originates from the variable tangential friction force which develops between the pendulum mass and the 3D surface as a result of a spatially-varying friction coefficient pattern. Namely, a friction coefficient is proposed that varies along the pendulum surface in proportion to the modulus of the 3D surface gradient. With such an assumption, the dissipative model of the absorber can be proven to be nonlinear homogeneous in the small displacement domain. The resulting homogeneous BPA (HBPA) has a fundamental advantage over conventional friction-type absorbers, because its equivalent damping ratio results independent on the amplitude of oscillations, and therefore its optimal performance does not depend on the excitation level. On the other hand, the HBPA is more compact than viscously damped BPAs because it does not need the installation of dampers. This paper presents the analytical model of the HBPA and an optimal methodology for its design. Numerical simulations of single- and multi-story building structures under wind and earthquake loads are presented to compare the HBPA with classical viscously damped BPAs. It is shown that the HBPA is a promising alternative to existing BPA types and that homogeneous tangential friction is an effective means to realize systems provided with amplitude-independent damping.

Keywords: amplitude-independent damping, homogeneous friction, pendulum nonlinear dynamics, structural control, vibration resonant absorbers

Procedia PDF Downloads 131

Authors: Giuliana Scuderi, Patrick Teuffel

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The proven vulnerability of the existing social housing building heritage to natural or induced earthquakes requires the development of new design concepts and conceptual method to preserve materials and object, at the same time providing new performances. An integrate intervention between civil engineering, building physics and architecture can convert the social housing districts from a critical part of the city to a strategic resource of revitalization. Referring to bio-mimicry principles the present research proposes a taxonomy with the exoskeleton of the insect, an external, light and resistant armour whose role is to protect the internal organs from external potentially dangerous inputs. In the same way, a “building exoskeleton”, acting from the outside of the building as an enclosing cage, can restore, protect and support the existing building, assuming a complex set of roles, from the structural to the thermal, from the aesthetical to the functional. This study evaluates the structural efficiency of shape memory alloys devices (SMADs) connecting the “building exoskeleton” with the existing structure to rehabilitate, in order to prevent the out-of-plane collapse of walls and for the passive dissipation of the seismic energy, with a calibrated operability in relation to the intensity of the horizontal loads. The two case studies of a masonry structure and of a masonry structure with concrete frame are considered, and for each case, a theoretical social housing building is exposed to earthquake forces, to evaluate its structural response with or without SMADs. The two typologies are modelled with the finite element program SAP2000, and they are respectively defined through a “frame model” and a “diagonal strut model”. In the same software two types of SMADs, called the 00-10 SMAD and the 05-10 SMAD are defined, and non-linear static and dynamic analyses, namely push over analysis and time history analysis, are performed to evaluate the seismic response of the building. The effectiveness of the devices in limiting the control joint displacements resulted higher in one direction, leading to the consideration of a possible calibrated use of the devices in the different walls of the building. The results show also a higher efficiency of the 00-10 SMADs in controlling the interstory drift, but at the same time the necessity to improve the hysteretic behaviour, to maximise the passive dissipation of the seismic energy.

Keywords: adaptive structure, biomimetic design, building exoskeleton, social housing, structural envelope, structural retrofitting

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Authors: Savitha Janakiraman, Shivakumar M. C

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Anidulafungin, an advanced class of antifungal agent used for the treatment of chronic fungal infections, is derived from Echinocandin B nucleus, an intermediate metabolite of Echinocandin B produced by Aspergillus nidulans. The enzyme acylase derived from the fermentation broth of Actinoplanes utahensis (NRRL 12052) plays a key role in the bioconversion of echinocandin B to echinocandin B nucleus. The membrane-bound nature of acylase and low levels of expression contributes to the rate-limiting process of enzymatic deacylation, hence low yields of ECB nucleus and anidulafungin. In the present study, this is addressed through novel genetic engineering approaches of overexpression and heterologous expression studies, immobilization of whole cells of Actinoplanes utahensis (NRRL 12052) and Co-cultivation studies. Overexpression of the acylase gene in Actinoplanes utahensis (NRRL 12052) was done by increasing the gene copy number to increase the echinocandin B nucleus production. Echinocandin B acylase gene, under the control of a PermE* promoter, was cloned in pSET152 vector and introduced into Actinoplanes utahensis (NRRL12052) by a ɸC31-directed site-specific recombination method. The resultant recombinant strain (C2-18) showed a 3-fold increase in acylase expression, which was confirmed by HPLC analysis. Pichia pastoris is one of the most effective and versatile host systems for the production of heterologous proteins. The ECB acylase gene was cloned into pPIC9K vector with AOX1 promoter and was transformed into Pichia pastoris (GS115). The acylase expression was confirmed by protein expression and bioconversion studies. The heterologous expression of acylase in Pichia pastoris, is a milestone in the development of antifungals. Actively growing cells of Actinoplanes utahensis (NRRL 12052) were immobilized and tested for bioconversion ability which showed >90% conversion in each cycle. The stability of immobilized cell beads retained the deacylation ability up to 60 days and reusability was confirmed up to 4 cycles. The significant findings from the study have revealed that immobilization of whole cells of Actinoplanes utahensis (NRRL 12052) could be an alternative option for bioconversion of echinocandin B to echinocandin B nucleus, which has not been reported to date. The concept of co-cultivation of Aspergillus nidulans and Actinoplanes utahensis strains for the production of the echinocandin B nucleus was also carried out in order to produce echinocandin B nucleus. The process completely reduced the ECB purification step and, therefore, could be recommended as an ingenious method to improve the yield of the ECB nucleus.

Keywords: acylase, anidulafungin, antifungals, Aspergillus nidulans

Procedia PDF Downloads 87

Authors: Teklay Gebrecherkos, Mahmud Abdulkadir

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Abstract: The emergence and subsequent rapid worldwide spread of the COVID-19 pandemic have posed a global crisis, with a tremendously increasing burden of infection, morbidity, and mortality risks. Recent studies have suggested that severe cases of COVID-19 are characterized by massive biochemical, hematological, and inflammatory alterations whose synergistic effect is estimated to progress to multiple organ damage and failure. In this regard, biochemical monitoring of COVID-19 patients, based on comprehensive laboratory assessments and findings, is expected to play a crucial role in effective clinical management and improving the survival rates of patients. However, biochemical markers that can be informative of COVID-19 patient risk stratification and predictor of clinical outcomes are currently scarcely available. The study aims to investigate the profiles of common biochemical markers and their influence on the severity of the COVID-19 infection in Tigray, Ethiopia. Methods: A laboratory-based cross-sectional study was conducted from July to August 2020 at Quiha College of Engineering, Mekelle University COVID-19 isolation and treatment center. Sociodemographic and clinical data were collected using a structured questionnaire. Whole blood was collected from each study participant, and serum samples were separated after being delivered to the laboratory. Hematological biomarkers were analyzed using FACS count, while organ tests and serum electrolytes were analyzed using ion-selective electrode methods using a Cobas-6000 series machine. Data was analyzed using SPSS Vs 20. Results: A total of 120 SARS-CoV-2 patients were enrolled during the study. The participants ranged between 18 and 91 years, with a mean age of 52 (±108.8). The majority (40%) of participants were between the ages of 60 and above. Patients with multiple comorbidities developed severe COVID-19, though not statistically significant (p=0.34). Mann-Whitney U test analysis showed that biochemical tests such as neuropile count (p=0.003), AST levels (p=0.050), serum creatinine (p=0.000), and serum sodium (p=0.015) were significantly correlated with severe COVID-19 disease as compared to non-severe disease. Conclusion: The severity of COVID-19 was associated with higher age, organ tests AST and creatinine, serum Na+, and elevated total neutrophile count. Thus, further study needs to be conducted to evaluate the alterations of biochemical biomarkers and their impact on COVID-19.

Keywords: COVID-19, biomarkers, mortality, Tigray, Ethiopia

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Authors: L. Joseph, B. Farid, F. Ravelet

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Fundamental studies were performed on bifurcation, instabilities and turbulence in Taylor-Couette flow and applied to many engineering applications like astrophysics models in the accretion disks, shrouded fans, and electric motors. Such rotating machinery performances need to have a better understanding of the fluid flow distribution to quantify the power losses and the heat transfer distribution. The present investigation is focused on high gap ratio of Taylor-Couette flow with high rotational speeds, for smooth and grooved surfaces. So far, few works has been done in a very narrow gap and with very high rotation rates and, to the best of our knowledge, not with this combination with grooved surface. We study numerically the turbulent flow between two coaxial cylinders where R1 and R2 are the inner and outer radii respectively, where only the inner is rotating. The gap between the rotor and the stator varies between 0.5 and 2 mm, which corresponds to a radius ratio η = R1/R2 between 0.96 and 0.99 and an aspect ratio Γ= L/d between 50 and 200, where L is the length of the rotor and d being the gap between the two cylinders. The scaling of the torque with the Reynolds number is determined at different gaps for different smooth and grooved surfaces (and also with different number of grooves). The fluid in the gap is air. Re varies between 8000 and 30000. Another dimensionless parameter that plays an important role in the distinction of the regime of the flow is the Taylor number that corresponds to the ratio between the centrifugal forces and the viscous forces (from 6.7 X 105 to 4.2 X 107). The torque will be first evaluated with RANS and U-RANS models, and compared to empirical models and experimental results. A mesh convergence study has been done for each rotor-stator combination. The results of the torque are compared to different meshes in 2D dimensions. For the smooth surfaces, the models used overestimate the torque compared to the empirical equations that exist in the bibliography. The closest models to the empirical models are those solving the equations near to the wall. The greatest torque achieved with grooved surface. The tangential velocity in the gap was always higher in between the rotor and the stator and not on the wall of rotor. Also the greater one was in the groove in the recirculation zones. In order to avoid endwall effects, long cylinders are used in our setup (100 mm), torque is measured by a co-rotating torquemeter. The rotor is driven by an air turbine of an automotive turbo-compressor for high angular velocities. The results of the experimental measurements are at rotational speed of up to 50 000 rpm. The first experimental results are in agreement with numerical ones. Currently, quantitative study is performed on grooved surface, to determine the effect of number of grooves on the torque, experimentally and numerically.

Keywords: Taylor-Couette flow, high gap ratio, grooved surface, high speed

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Authors: Emmanuel Ophel Gilbert, Williams Speret

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The control for fluid flow behaviours of viscous fluids and heat transfer occurrences within heated mini-channel is considered. Heat transfer and flow characteristics of different viscous liquids, such as engine oil, automatic transmission fluid, one-half ethylene glycol, and deionized water were numerically analyzed. Some mathematical applications such as Fourier series and Laplace Z-Transforms were employed to ascertain the behaviour-wave like structure of these each viscous fluids. The steady, laminar flow and heat transfer equations are reckoned by the aid of numerical simulation technique. Further, this numerical simulation technique is endorsed by using the accessible practical values in comparison with the anticipated local thermal resistances. However, the roughness of this mini-channel that is one of the physical limitations was also predicted in this study. This affects the frictional factor. When an additive such as tetracycline was introduced in the fluid, the heat input was lowered, and this caused pro rata effect on the minor and major frictional losses, mostly at a very minute Reynolds number circa 60-80. At this ascertained lower value of Reynolds numbers, there exists decrease in the viscosity and minute frictional losses as a result of the temperature of these viscous liquids been increased. It is inferred that the three equations and models are identified which supported the numerical simulation via interpolation and integration of the variables extended to the walls of the mini-channel, yields the utmost reliance for engineering and technology calculations for turbulence impacting jets in the near imminent age. Out of reasoning with a true equation that could support this control for the fluid flow, Navier-stokes equations were found to tangential to this finding. Though, other physical factors with respect to these Navier-stokes equations are required to be checkmated to avoid uncertain turbulence of the fluid flow. This paradox is resolved within the framework of continuum mechanics using the classical slip condition and an iteration scheme via numerical simulation method that takes into account certain terms in the full Navier-Stokes equations. However, this resulted in dropping out in the approximation of certain assumptions. Concrete questions raised in the main body of the work are sightseen further in the appendices.

Keywords: frictional losses, heat transfer, laminar flow, mini-channel, number simulation, Reynolds number, turbulence, viscous fluids

Procedia PDF Downloads 158

Authors: Muhammad Khairi bin Sulaiman

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The utilization of Building Information Modelling (BIM) in the construction industry has provided an opportunity for designers in the Architecture, Engineering and Construction (AEC) industry to proceed from the conventional method of using manual drafting to a way that creates alternative designs quickly, produces more accurate, reliable and consistent outputs. By using BIM Software, designers can create digital content that manipulates the use of data using the parametric model of BIM. With BIM software, more alternative designs can be created quickly and design problems can be explored further to produce a better design faster than conventional design methods. Generally, BIM is used as a documentation mechanism and has not been fully explored and utilised its capabilities as a design tool. Relative to the current issue, Modular Coordination (MC) design as a sustainable design practice is encouraged since MC design will reduce material wastage through standard dimensioning, pre-fabrication, repetitive, modular construction and components. However, MC design involves a complex process of rules and dimensions. Therefore, a tool is needed to make this process easier. Since the parameters in BIM can easily be manipulated to follow MC rules and dimensioning, thus, the integration of BIM software with MC design is proposed for architects during the design stage. With this tool, there will be an improvement in acceptance and practice in the application of MC design effectively. Consequently, this study will analyse and explore the function and customization of BIM objects and the capability of BIM software to expedite the application of MC design during the design stage for architects. With this application, architects will be able to create building models and locate objects within reference modular grids that adhere to MC rules and dimensions. The parametric modeling capabilities of BIM will also act as a visual tool that will further enhance the automation of the 3-Dimensional space planning modeling process. (Method) The study will first analyze and explore the parametric modeling capabilities of rule-based BIM objects, which eventually customize a reference grid within the rules and dimensioning of MC. Eventually, the approach will further enhance the architect's overall design process and enable architects to automate complex modeling, which was nearly impossible before. A prototype using a residential quarter will be modeled. A set of reference grids guided by specific MC rules and dimensions will be used to develop a variety of space planning and configuration. With the use of the design, the tool will expedite the design process and encourage the use of MC Design in the construction industry.

Keywords: building information modeling, modular coordination, space planning, customization, BIM application, MC space planning

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Authors: Elena Pummer, Holger Schuettrumpf

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By today underground pumped storage plants as an outstanding alternative for classical pumped storage plants do not exist. They are needed to ensure the required balance between production and demand of energy. As a short to medium term storage pumped storage plants have been used economically over a long period of time, but their expansion is limited locally. The reasons are in particular the required topography and the extensive human land use. Through the use of underground reservoirs instead of surface lakes expansion options could be increased. Fulfilling the same functions, several hydrodynamic processes result in the specific design of the underground reservoirs and must be implemented in the planning process of such systems. A combined 3D numerical and experimental approach leads to currently unknown results about the occurring wave types and their behavior in dependence of different design and operating criteria. For the 3D numerical simulations, OpenFOAM was used and combined with an experimental approach in the laboratory of the Institute of Hydraulic Engineering and Water Resources Management at RWTH Aachen University, Germany. Using the finite-volume method and an explicit time discretization, a RANS-Simulation (k-ε) has been run. Convergence analyses for different time discretization, different meshes etc. and clear comparisons between both approaches lead to the result, that the numerical and experimental models can be combined and used as hybrid model. Undular bores partly with secondary waves and breaking bores occurred in the underground reservoir. Different water levels and discharges change the global effects, defined as the time-dependent average of the water level as well as the local processes, defined as the single, local hydrodynamic processes (water waves). Design criteria, like branches, directional changes, changes in cross-section or bottom slope, as well as changes in roughness have a great effect on the local processes, the global effects remain unaffected. Design calculations for underground pumped storage plants were developed on the basis of existing formulae and the results of the hybrid approach. Using the design calculations reservoirs heights as well as oscillation periods can be determined and lead to the knowledge of construction and operation possibilities of the plants. Consequently, future plants can be hydraulically optimized applying the design calculations on the local boundary conditions.

Keywords: energy storage, experimental approach, hybrid approach, undular and breaking Bores, 3D numerical approach

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Authors: Iman Shabanzadeh

Abstract:

Earthquake is known as one of the most frequent natural hazards in Iran. Therefore, policy making to improve the strengthening of structures is one of the requirements of the approach to prevent and reduce the risk of the destructive effects of earthquakes. In order to choose the optimal policy in the face of earthquakes, this article tries to examine the cost of financial damages caused by earthquakes in the building sector and compare it with the costs of retrofitting. In this study, the results of adopting the scenario of "action after the earthquake" and the policy scenario of "strengthening structures before the earthquake" have been collected, calculated and finally analyzed by putting them together. Methodologically, data received from governorates and building retrofitting engineering companies have been used. The scope of the study is earthquakes occurred in the geographical area of Iran, and among them, eight earthquakes have been specifically studied: Miane, Ahar and Haris, Qator, Momor, Khorasan, Damghan and Shahroud, Gohran, Hormozgan and Ezgole. The main basis of the calculations is the data obtained from retrofitting companies regarding the cost per square meter of building retrofitting and the data of the governorate regarding the power of earthquake destruction, the realized costs for the reconstruction and construction of residential units. The estimated costs have been converted to the value of 2021 using the time value of money method to enable comparison and aggregation. The cost-benefit comparison of the two policies of action after the earthquake and retrofitting before the earthquake in the eight earthquakes investigated shows that the country has suffered five thousand billion Tomans of losses due to the lack of retrofitting of buildings against earthquakes. Based on the data of the Budget Law's of Iran, this figure was approximately twice the budget of the Ministry of Roads and Urban Development and five times the budget of the Islamic Revolution Housing Foundation in 2021. The results show that the policy of retrofitting structures before an earthquake is significantly more optimal than the competing scenario. The comparison of the two policy scenarios examined in this study shows that the policy of retrofitting buildings before an earthquake, on the one hand, prevents huge losses, and on the other hand, by increasing the number of earthquake-resistant houses, it reduces the amount of earthquake destruction. In addition to other positive effects of retrofitting, such as the reduction of mortality due to earthquake resistance of buildings and the reduction of other economic and social effects caused by earthquakes. These are things that can prove the cost-effectiveness of the policy scenario of "strengthening structures before earthquakes" in Iran.

Keywords: disaster economy, earthquake economy, cost-benefit analysis, resilience

Procedia PDF Downloads 40