Search results for: currents and potentials matrix

Authors: Glykeria A. Visvini, George N. Mathioudakis, Amaia Soto Beobide, Aris E. Giannakas, George A. Voyiatzis

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Polymeric nanocomposites have generated considerable interest in both academic research and industry because their properties can be tailored by adjusting the type & concentration of nano-inclusions, resulting in complementary and adaptable characteristics. The exceptional and/or unique properties of the nanocomposites, including the high mechanical strength and stiffness, the ease of processing, and their lightweight nature, are attributed to the high surface area, the electrical and/or thermal conductivity of the nano-fillers, which make them appealing materials for a wide range of engineering applications. Polymeric «breathable» membranes enabling water vapor permeability (WVP) can be designed either by using micro/nano-fillers with the ability to interrupt the continuity of the polymer phase generating micro/nano-porous structures or/and by creating micro/nano-pores into the composite material by uniaxial/biaxial stretching. Among the nanofillers, carbon nanotubes (CNTs) exhibit particular high WVP and for this reason, they have already been proposed for gas separation membranes. In a similar context, they could prove to be promising alternative/complementary filler nano-materials, for the development of "breathable" products. Polypropylene (PP) is a commonly utilized thermoplastic polymer matrix in the development of composite films, due to its easy processability and low price, combined with its good chemical & physical properties. PP is known to present several crystalline phases (α, β and γ), depending on the applied treatment process, which have a significant impact on its final properties, particularly in terms of WVP. Specifically, the development of the β-phase in PP in combination with stretching is anticipated to modify the crystalline behavior and extend the microporosity of the polymer matrix exhibiting enhanced WVP. The primary objective of this study is to develop breathable nano-carbon based (functionalized MWCNTs) PP composite membranes, potentially also avoiding the stretching process. This proposed alternative is expected to have a better performance/cost ratio over current stretched PP/CaCO3 composite benchmark membranes. The focus is to investigate the impact of both β-nucleator(s) and nano-carbon fillers on water vapor transmission rate properties of relevant PP nanocomposites.

Keywords: carbon nanotubes, nanocomposites, nucleating agents, polypropylene, water vapor permeability

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Authors: Kittisak Jantanasakulwong, Toshiaki Ougizawa

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Thermoplastic starch (TPS) was prepared by melt-blending of cassava starch with glycerol (70/30 wt%/wt%) at 130 ◦C for 10 min. Chitosan (CTS) was used as a compatibilizer. TPS/CTS blend was melt-blended with maleic anhydride grafted ethylene-1-butene rubber (EB-MAH) in the composition of 80/20 respectively. Addition of CTS in TPS/EB-MAH blend decreased particles size of EB-MAH rubber to 1µm in TPS matrix. Mechanical properties, solubility, swelling property, morphology, and water contact angle of TPS/EB-MAH blend were improved by CTS incorporation. FTIR confirmed a reaction had occurred between amino groups (-NH2) of CTS and the MAH groups of EB-MAH. This reaction and the enhanced miscibility between TPS and CTS improved morphology and properties of the TPS/EB-MAH/CTS blend.

Keywords: thermoplastic starch, rubber, reactive blending, chitosan

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Authors: N. Dahraoui, M. Boulakroune, D. Benatia

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In this paper, the improvement by deconvolution of the depth resolution in Secondary Ion Mass Spectrometry (SIMS) analysis is considered. Indeed, we have developed a new Tikhonov-Miller deconvolution algorithm where a priori model of the solution is included. This is a denoisy and pre-deconvoluted signal obtained from: firstly, by the application of wavelet shrinkage algorithm, secondly by the introduction of the obtained denoisy signal in an iterative deconvolution algorithm. In particular, we have focused the light on the effect of the iterations number on the evolution of the deconvoluted signals. The SIMS profiles are multilayers of Boron in Silicon matrix.

Keywords: DRF, in-depth resolution, multiresolution deconvolution, SIMS, wavelet shrinkage

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Authors: M. J. Park, S. H. Lee, C. H. Lee, O. M. Kwon

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This paper studies a secondary voltage control framework of the microgrids based on the consensus for a communication network of multiagent. The proposed control is designed by the communication network with one-way links. The communication network is modeled by a directed graph. At this time, the concept of sampling is considered as the communication constraint among each distributed generator in the microgrids. To analyze the sampling effects on the secondary voltage control of the microgrids, by using Lyapunov theory and some mathematical techniques, the sufficient condition for such problem will be established regarding linear matrix inequality (LMI). Finally, some simulation results are given to illustrate the necessity of the consideration of the sampling effects on the secondary voltage control of the microgrids.

Keywords: microgrids, secondary control, multiagent, sampling, LMI

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Authors: Brandtner Patrick, Staberhofer Franz

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Logistics and Supply Chain Management are of crucial importance for organisational success. In the era of Digitalization, several implications and improvement potentials for these domains arise, which at the same time could lead to decreased competitiveness and could endanger long-term company success if ignored or neglected. However, empirical research on the issue of Digitalization and benefits purported to it by practitioners is scarce and mainly focused on single technologies or separate, isolated Supply Chain blocks as e.g. distribution logistics or procurement only. The current paper applies a holistic focus group approach to elaborate practitioner use cases at the nexus of the concepts of Supply Chain Management (SCM) and Digitalization. In the course of three focus group workshops with over 45 participants from more than 20 organisations, a comprehensive set of benefit entitlements and areas for improvement in terms of applying digitalization to SCM is developed. The main results of the paper indicate the relevance of Digitalization being realized in practice. In the form of seventeen concrete research action fields, the benefit entitlements are aggregated and transformed into potential starting points for future research projects in this area. The main contribution of this paper is an empirically grounded basis for future research projects and an overview of actual research action fields from practitioners’ point of view.

Keywords: digital supply chain, digital transformation, supply chain management, value networks

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Authors: Saleh O. Allehabi, V. A. Dzubaa, V. V. Flambaum, Jiguang Li, A. V. Afanasjev, S. E. Agbemava

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Recently developed versions of the configuration method for open shells, configuration interaction with perturbation theory (CIPT), and configuration interaction with many-body perturbation theory (CI+MBPT) techniques are used to study the electronic structure of Er, Fm, and No atoms. Excitation energies of odd states connected to the even ground state by electric dipole transitions, the corresponding transition rates, isotope shift, hyperfine structure, ionization potentials, and static scalar polarizabilities are calculated. The way of extracting parameters of nuclear charge distribution beyond nuclear root mean square (RMS) radius, e.g., a parameter of quadrupole deformation β, is demonstrated. In nuclei with spin > 1/2, parameter β is extracted from the quadrupole hyperfine structure. With zero nuclear spin or spin 1/2, it is impossible since quadrupole zero, so a different method was developed. The measurements of at least two atomic transitions are needed to disentangle the contributions of the changes in deformation and nuclear RMS radius into field isotopic shift. This is important for testing nuclear theory and for searching for the hypothetical island of stability. Fm and No are heavy elements approaching the superheavy region, for which the experimental data are very poor, only seven lines for the Fm element and one line for the No element. Since Er and Fm have similar electronic structures, calculations for Er serve as a guide to the accuracy of the calculations. Twenty-eight new levels of Fm atom are reported.

Keywords: atomic spectra, electronic transitions, isotope effect, electron correlation calculations for atoms

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Authors: M. Stefanovska, B. Samakoski, S. Risteska, G. Maneski

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In this study was performed in situ consolidation of polypropylene matrix/glass reinforced roving by combining heating systems and roll pressing. The commingled roving during hoop winding was winded on a cylindrical mandrel. The work also presents the advances made in the processing of these materials into composites by conventional technique filament winding. Experimental studies were performed with changing parameters – temperature, pressure and speed. Finally, it describes the investigation of the optimal processing conditions that maximize the mechanical properties of the composites. These properties are good enough for composites to be used as engineering materials in many structural applications.

Keywords: commingled fiber, consolidation heat, filament winding, voids

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Authors: Maria Pintea, Nigel Mason

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Induced chemistry is one of the newest pathways in the nanotechnology field with applications in the focused electron beam induced processes for deposition of nm scale structures. Si(OPr)₄ and Ti(OEt)₄ are two of the precursors that have not been so extensively researched, though highly sought for semiconductor and medical applications fields, the two compounds make good candidates for FEBIP and are the subject of velocity slice map imaging analysis for deposition purposes, offering information on kinetic energies, fragmentation channels, and angular distributions. The velocity slice map imaging technique is a method used for the characterization of molecular dynamics of the molecule and the fragmentation channels as a result of induced chemistry. To support the gas-phase analysis, Meso-Bio-Nano simulations of irradiation dynamics studies are employed with final results on Fe(CO)₅ deposited on various substrates. The software is capable of running large scale simulations for complex biomolecular, nano- and mesoscopic systems with applications to thermos-mechanical DNA damage, complex materials, gases, nanoparticles for cancer research and deposition applications for nanotechnology, using a large library of classical potentials, many-body force fields, molecular force fields involved in the classical molecular dynamics.

Keywords: focused electron beam induced deposition, FEBID, induced chemistry, molecular dynamics, velocity map slice imaging

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Authors: Er-Yuan Chuang

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Bio-mimetic matters have biological functionalities. This might be valuable in the development of versatile biomaterials. At biological fields, protein-based materials might be components to form a 3D network of extracellular biomolecules, containing growth factors. Also, the protein-based biomaterial provides biochemical and structural assistance of adjacent cells. In this study, we try to prepare protein based biomaterial, which was harvested from living animal. We analyzed it’s chemical, physical and biological property in vitro. Besides, in vivo bio-interaction of the prepared biomimetic matrix was tested in an animal model. The protein-based biomaterial has degradability and biocompatibility. This development could be used for tissue regenerations and be served as platform technologies.

Keywords: protein based, in vitro study, in vivo study, biomaterials

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Authors: Hyunsik Park

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As the rate of cerebrovascular disease increases in old populations, the prevalence rate of vascular dementia would be expected. Therefore, authors designed this study to find out the possibility of somatosensory evoked potentials(SSEP) as a parameter for early diagnosis and prognosis prediction of vascular dementia in cortical vascular dementia patients. 21 patients who met the criteria for vascular dementia according to DSM-IV,ICD-10and NINDS-AIREN with the history of recent cognitive impairment, fluctuation progression, and neurologic deficit. We subdivided these patients into two groups; a mild dementia and a severe dementia groups by MMSE and CDR score; and analysed comparison between normal control group and patient control group who have been cerebrovascular attack(CVA) history without dementia by using N20 latency and amplitude of median nerve. In this study, mild dementia group showed significant differences on latency and amplitude with normal control group(p-value<0.05) except patient control group(p-value>0.05). Severe dementia group showed significant differences both normal control group and patient control group.(p-value<0.05, <001). Since no significant difference has founded between mild dementia group and patient control group, SSEP has limitation to use for early diagnosis test. However, the comparison between severe dementia group and others showed significant results which indicate SSEP can predict the prognosis of vascular dementia in cortical vascular dementia patients.

Keywords: SSEP, cortical vascular dementia, N20 latency, N20 amplitude

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Authors: Anika Zafiah M. Rus, Nur Munirah Abdullah, M. F. L. Abdullah

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The fabrication and characterization of composite films of graphite- bioepoxy is described. Free-standing thin films of ~0.1 mm thick are prepared using a simple solution mixing with mass proportion of 7/3 (bioepoxy/graphite) and drop casting at room temperature. Fourier transform infra-red spectroscopy (FTIR) and Ultraviolet-visible (UV-vis) spectrophotometer are performed to evaluate the changes in chemical structure and adsorption spectra arising with the increasing of graphite weight loading (wt.%) into the biopolymer matrix. The morphologic study shows a homogeneously dispersed and strong particle bonding between the graphite and the bioepoxy, with conductivity of the film 103 S/m, confirming the efficiency of the processes.

Keywords: absorbance peak, biopolymer, graphite- bioepoxy composites, particle bonding

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Authors: Guillaume Richard, Sarra Zaied

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Marine waste quantities increase more and more, 5 million tons of plastic waste enter the ocean every year. Their spatiotemporal distribution is never homogeneous and depends mainly on the hydrodynamic characteristics of the environment, as well as the size and location of the waste. As part of optimizing collect of marine plastic wastes, it is important to measure and monitor their evolution over time. In this context, diverse studies have been dedicated to describing waste behavior in order to identify its accumulation in ocean areas. None of the existing tools which track objects at sea had the objective of tracking down a slick of waste. Moreover, the applications related to marine waste are in the minority compared to rescue applications or oil slicks tracking applications. These approaches are able to accurately simulate an object's behavior over time but not during the collection mission of a waste sheet. This paper presents numerical modeling of a boat’s wake impact on the floating marine waste behavior during a collection mission. The aim is to predict the trajectory of a marine waste slick to optimize its collection using meteorological data of ocean currents, wind, and possibly waves. We have made the choice to use Ocean Parcels which is a Python library suitable for trajectoring particles in the ocean. The modeling results showed the important role of advection and diffusion processes in the spatiotemporal distribution of floating plastic litter. The performance of the proposed method was evaluated on real data collected from the Copernicus Marine Environment Monitoring Service (CMEMS). The results of the evaluation in Cape of Good Hope (South Africa) prove that the proposed approach can effectively predict the position and velocity of marine litter during collection, which allowed for optimizing time and more than $90\%$ of the amount of collected waste.

Keywords: marine litter, advection-diffusion equation, sea current, numerical model

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Authors: Yasir M. Alyazichi, Brian G. Jones, Errol McLean, Hamd N. Altalyan, Ali K. M. Al-Nasrawi

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The main purpose of this study is to assess the sediment quality and potential ecological risk in marine sediments in Gymea Bay located in south Sydney, Australia. A total of 32 surface sediment samples were collected from the bay. Current track trajectories and velocities have also been measured in the bay. The resultant trace elements were compared with the adverse biological effect values Effect Range Low (ERL) and Effect Range Median (ERM) classifications. The results indicate that the average values of chromium, arsenic, copper, zinc, and lead in surface sediments all reveal low pollution levels and are below ERL and ERM values. The highest concentrations of trace elements were found close to discharge points and in the inner bay, and were linked with high percentages of clay minerals, pyrite and organic matter, which can play a significant role in trapping and accumulating these elements. The lowest concentrations of trace elements were found to be on the shoreline of the bay, which contained high percentages of sand fractions. It is postulated that the fine particles and trace elements are disturbed by currents and tides, then transported and deposited in deeper areas. The current track velocities recorded in Gymea Bay had the capability to transport fine particles and trace element pollution within the bay. As a result, hydrodynamic measurements were able to provide useful information and to help explain the distribution of sedimentary particles and geochemical properties. This may lead to knowledge transfer to other bay systems, including those in remote areas. These activities can be conducted at a low cost, and are therefore also transferrable to developing countries. The advent of portable instruments to measure trace elements in the field has also contributed to the development of these lower cost and easily applied methodologies available for use in remote locations and low-cost economies.

Keywords: current track velocities, gymea bay, surface sediments, trace elements

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Authors: Riddhi Chopra

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While China’s friendship with a number of countries has waxed and waned over the decades, Sino-Pak relationship is said to have withstood the vicissitudes of larger international politics as well as changes in regional and domestic currents. Pakistan, one of the first countries to recognize the People’s Republic of China, thus providing China with a corridor into the energy rich Muslim states which was reciprocated with a continual stream of no-strings-attached military hardware and defense-related assistance from Beijing. The joint enmity towards India also provided the initial thrust to a burgeoning Sino-Pak friendship. This paper intends to provide a profound analysis of the strategic relation between China-Pakistan and examine India as a determining factor. The Pakistan-China strategic relationship has been conventionally viewed by India as a zero sum game, wherein any gains accrued by Pakistan or China through their partnership is seen as a direct detriment to the evolution of India-Pakistan or India-China relation. The paper evaluates various factors which were crucial for the synthesis of such a strong relation and presents a comprehensive study of the various policies and programs that have been undertaken by the two countries to tie India to South Asia and reduce its sphere of influence. The geographic dynamics is said to breed a natural coalition, dominating the strategic ambitions of both Beijing and Islamabad hence directing their relationship. In addition to the obvious geopolitical factors, there are several dense collaborations between the two nations knitting a relatively close partnership. Moreover, an attempt has been made to assess the irritants in China-Pak relations and the initiatives taken by the two to further strengthen it. Current trends in diplomatic, economic and defense cooperation – along with the staunch affinity rooted in history and consistent geo-strategic interests – points to a strong and strengthening relationship, significant in directing India’s foreign and security policies. This paper seeks to analyze the changing power dynamics of the China-Pak nexus with external actors such as US and India with an ulterior motive of their own and predict the change in power dynamics between the four countries.

Keywords: China, Pakistan, India, strategy

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Authors: Trevor Sabiston, Mohsen Mohammadi, Mohammed Cherkaoui, Kaan Inal

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A new micromechanics framework is developed for long fibre reinforced composites using a single fibre surrounded by a functionally graded interphase and matrix as a representative unit cell. The unit cell is formulated to represent any number of aligned fibres by a single fibre. Using this model the elastic response of long fibre composites is predicted in all directions. The model is calibrated to experimental results and shows very good agreement in the elastic regime. The differences between the proposed model and existing models are discussed.

Keywords: computational mechanics, functionally graded interphase, long fibre composites, micromechanics

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Authors: Hai Hoang, Thanh Xuan Nguyen Thi, Guillaume Galliero

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Coarse-Grained (CG) molecular simulations have shown to be an efficient way to estimate thermophysical (static and dynamic) properties of fluids. Several strategies have been developed and reported in the literature for defining CG molecular models. Among them, those based on a top-down strategy (i.e. CG molecular models related to macroscopic observables), despite being heuristic, have increasingly gained attention. This is probably due to its simplicity in implementation and its ability to provide reasonable results for not only simple but also complex systems. Regarding simple Force-Fields associated with these CG molecular models, it has been found that the four parameters Mie chain model is one of the best compromises to describe thermophysical static properties (e.g. phase diagram, saturation pressure). However, parameterization procedures of these Mie-chain GC molecular models given in literature are generally insufficient to simultaneously provide static and dynamic (e.g. viscosity) properties. To deal with such situations, we have extended the corresponding states by using a quantity associated with the liquid viscosity. Results obtained from molecular simulations have shown that our approach is able to yield good estimates for both static and dynamic thermophysical properties for various real non-associating fluids. In addition, we will show that on simple (e.g. phase diagram, saturation pressure) and complex (e.g. thermodynamic response functions, thermodynamic energy potentials) static properties, results of our scheme generally provides improved results compared to existing approaches.

Keywords: coarse-grained model, mie potential, molecular simulations, thermophysical properties, phase equilibria

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Authors: Nidhal Jamia, Sami El-Borgi

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In this paper, the problem of a mixed-Mode crack embedded in an infinite medium made of a functionally graded piezoelectric material (FGPM) with crack surfaces subjected to electro-mechanical loadings is investigated. Eringen’s non-local theory of elasticity is adopted to formulate the governing electro-elastic equations. The properties of the piezoelectric material are assumed to vary exponentially along a perpendicular plane to the crack. Using Fourier transform, three integral equations are obtained in which the unknown variables are the jumps of mechanical displacements and electric potentials across the crack surfaces. To solve the integral equations, the unknowns are directly expanded as a series of Jacobi polynomials, and the resulting equations solved using the Schmidt method. In contrast to the classical solutions based on the local theory, it is found that no mechanical stress and electric displacement singularities are present at the crack tips when nonlocal theory is employed to investigate the problem. A direct benefit is the ability to use the calculated maximum stress as a fracture criterion. The primary objective of this study is to investigate the effects of crack length, material gradient parameter describing FGPMs, and lattice parameter on the mechanical stress and electric displacement field near crack tips.

Keywords: functionally graded piezoelectric material (FGPM), mixed-mode crack, non-local theory, Schmidt method

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Authors: Michael Sigruener, Dirk Muscat, Nicole Struebbe

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Fiber reinforcement is a state of the art to enhance mechanical properties in plastics. For concrete and civil engineering, steel reinforcements are commonly used. Steel reinforcements show disadvantages in their chemical resistance and weight, whereas polymer fibers' major problems are in fiber-matrix adhesion and mechanical properties. In spite of these facts, longevity and easy handling, as well as chemical resistance motivate researches to develop a polymeric material for fiber reinforced concrete. Adhesion and interfacial mechanism in fiber-polymer-composites are already studied thoroughly. For polymer fibers used as concrete reinforcement, the bonding behavior still requires a deeper investigation. Therefore, several differing polymers (e.g., polypropylene (PP), polyamide 6 (PA6) and polyetheretherketone (PEEK)) were spun into fibers via single screw extrusion and monoaxial stretching. Fibers then were embedded in a concrete matrix, and Single-Fiber-Pull-Out-Tests (SFPT) were conducted to investigate bonding characteristics and microstructural interface of the composite. Differences in maximum pull-out-force, displacement and slope of the linear part of force vs displacement-function, which depicts the adhesion strength and the ductility of the interfacial bond were studied. In SFPT fiber, debonding is an inhomogeneous process, where the combination of interfacial bonding and friction mechanisms add up to a resulting value. Therefore, correlations between polymeric properties and pull-out-mechanisms have to be emphasized. To investigate these correlations, all fibers were introduced to a series of analysis such as differential scanning calorimetry (DSC), contact angle measurement, surface roughness and hardness analysis, tensile testing and scanning electron microscope (SEM). Of each polymer, smooth and abraded fibers were tested, first to simulate the abrasion and damage caused by a concrete mixing process and secondly to estimate the influence of mechanical anchoring of rough surfaces. In general, abraded fibers showed a significant increase in maximum pull-out-force due to better mechanical anchoring. Friction processes therefore play a major role to increase the maximum pull-out-force. The polymer hardness affects the tribological behavior and polymers with high hardness lead to lower surface roughness verified by SEM and surface roughness measurements. This concludes into a decreased maximum pull-out-force for hard polymers. High surface energy polymers show better interfacial bonding strength in general, which coincides with the conducted SFPT investigation. Polymers such as PEEK or PA6 show higher bonding strength in smooth and roughened fibers, revealed through high pull-out-force and concrete particles bonded on the fiber surface pictured via SEM analysis. The surface energy divides into dispersive and polar part, at which the slope is correlating with the polar part. Only polar polymers increase their SFPT-function slope due to better wetting abilities when showing a higher bonding area through rough surfaces. Hence, the maximum force and the bonding strength of an embedded fiber is a function of polarity, hardness, and consequently surface roughness. Other properties such as crystallinity or tensile strength do not affect bonding behavior. Through the conducted analysis, it is now feasible to understand and resolve different effects in pull-out-behavior step-by-step based on the polymer properties itself. This investigation developed a roadmap on how to engineer high adhering polymeric materials for fiber reinforcement of concrete.

Keywords: fiber-matrix interface, polymeric fibers, fiber reinforced concrete, single fiber pull-out test

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Authors: A. Yönetken, A. Erol, A. Yakar, G. Peşmen

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The microstructure, mechanical properties and metalgraphic characteristics of Ni plated AlN-Astaloy Cr-M powders were investigated using specimens produced by tube furnace sintering at 1000-1400 °C temperature. A uniform nickel layer on AlN powders was deposited prior to sintering using electroless plating technique. A composite consisting of ternary additions, metallic phase, Ni and ceramic phase AlN within a matrix of Astaloy Cr-M had been prepared under Ar shroud and then tube furnace sintered. The experimental results carried out by using XRD (X-Ray Diffraction) and SEM (Scanning Electron Microscope) for composition (10% AlN-Astaloy Cr-M) 10% Ni at 1400 °C suggest that the best properties as 132.45HB and permittivity were obtained at 1400 °C.

Keywords: composite, electroless nickel plating, powder metallurgy, sintering

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Authors: Mojtaba Hakimi-Moghaddam

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Positive realness as the most important property of driving point impedance of passive electrical networks appears in the control systems stability theory in 1960’s. There are three important subsets of positive real (PR) systems are introduced by researchers, that is, loos-less positive real (LLPR) systems, weakly strictly positive real (WSPR) systems and strictly positive real (SPR) systems. In this paper, definitions, properties, lemmas, and theorems related to family of positive real systems are summarized. Properties in both frequency domain and state space representation of system are explained. Also, several illustrative examples are presented.

Keywords: real rational matrix transfer functions, positive realness property, strictly positive realness property, Hermitian form asymptotic property, pole-zero properties

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Authors: Elena Petersen, Inna Kornienko, Svetlana Guryeva, Sergey Simakov

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In vitro organoid cultivation requires the simultaneous provision of necessary vascularization and nutrients perfusion of cells during organoid development. However, many aspects of this problem are still unsolved. The functionality of vascular network intergrowth is limited during early stages of organoid development since a function of the vascular network initiated on final stages of in vitro organoid cultivation. Therefore, a microchannel network should be created in early stages of organoid cultivation in hydrogel matrix aimed to conduct and maintain minimally required the level of nutrients perfusion for all cells in the expanding organoid. The network configuration should be designed properly in order to exclude hypoxic and necrotic zones in expanding organoid at all stages of its cultivation. In vitro vascularization is currently the main issue within the field of tissue engineering. As perfusion and oxygen transport have direct effects on cell viability and differentiation, researchers are currently limited only to tissues of few millimeters in thickness. These limitations are imposed by mass transfer and are defined by the balance between the metabolic demand of the cellular components in the system and the size of the scaffold. Current approaches include growth factor delivery, channeled scaffolds, perfusion bioreactors, microfluidics, cell co-cultures, cell functionalization, modular assembly, and in vivo systems. These approaches may improve cell viability or generate capillary-like structures within a tissue construct. Thus, there is a fundamental disconnect between defining the metabolic needs of tissue through quantitative measurements of oxygen and nutrient diffusion and the potential ease of integration into host vasculature for future in vivo implantation. A model is proposed for growth prognosis of the organoid perfusion based on joint simulations of general nutrient diffusion, nutrient diffusion to the hydrogel matrix through the contact surfaces and microchannels walls, nutrient consumption by the cells of expanding organoid, including biomatrix contraction during tissue development, which is associated with changed consumption rate of growing organoid cells. The model allows computing effective microchannel network design giving minimally required the level of nutrients concentration in all parts of growing organoid. It can be used for preliminary planning of microchannel network design and simulations of nutrients supply rate depending on the stage of organoid development.

Keywords: 3D model, consumption model, diffusion, spheroid, tissue organoid

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Authors: D. M. El-Tanbouly, R. M. Abdelsalam, A. S. Attia, M. T. Abdel-Aziz

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Lipopolysaccharide (LPS) endotoxin, a component of the outer membrane of Gram-negative bacteria, is involved in the pathogenesis of sepsis. LPS administration induces systemic inflammation that mimics many of the initial clinical features of sepsis and has deleterious effects on several organs including the liver and eventually leading to septic shock and death. The present study aimed to investigate the protective effect of magnesium, a well-known cofactor in many enzymatic reactions and a critical component of the antioxidant system, on hepatic damage associated with LPS induced- endotoxima in mice. Mg (20 and 40 mg/kg, po) was administered for 7 consecutive days. Systemic inflammation was induced one hour after the last dose of Mg by a single dose of LPS (2 mg/kg, ip) and three hours thereafter plasma was separated, animals were sacrificed and their livers were isolated. LPS-treated mice suffered from hepatic dysfunction revealed by histological observation, elevation in plasma transaminases activities, C-reactive protein content and caspase-3, a critical marker of apoptosis. Liver inflammation was evident by elevation in liver cytokines contents (TNF-α and IL-10) and myeloperoxidase (MPO) activity. Additionally, oxidative stress was manifested by increased liver lipoperoxidation, glutathione depletion, elevated total nitrate/nitrite (NOx) content and glutathione peroxidase (GPx) activity. Pretreatment with Mg largely mitigated these alternations through its anti-inflammatory and antioxidant potentials. Mg, therefore, could be regarded as an effective strategy for prevention of liver damage associated with septicemia.

Keywords: LPS, liver damage, magnesium, septicemia

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Authors: O. Ubani, H. I. Atagana, M. S. Thantsha, R. Adeleke

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The oil sludge components (polycyclic aromatic hydrocarbons, PAHs) have been found to be cytotoxic, mutagenic and potentially carcinogenic and microorganisms such as bacteria and fungi can degrade the oil sludge to less toxic compounds such as carbon dioxide, water and salts. In the present study, we isolated different bacteria with PAH-degrading potentials from the co-composting of oil sludge and different animal manure. These bacteria were isolated on the mineral base medium and mineral salt agar plates as a growth control. A total of 31 morphologically distinct isolates were carefully selected from 5 different compost treatments for identification using polymerase chain reaction (PCR) of the 16S rDNA gene with specific primers (16S-P1 PCR and 16S-P2 PCR). The amplicons were sequenced and sequences were compared with the known nucleotides from the gene bank database. The phylogenetical analyses of the isolates showed that they belong to 3 different clades namely Firmicutes, Proteobacteria and Actinobacteria. These bacteria identified were closely related to genera Bacillus, Arthrobacter, Staphylococcus, Brevibacterium, Variovorax, Paenibacillus, Ralstonia and Geobacillus species. The results showed that Bacillus species were more dominant in all treated compost piles. Based on their characteristics these bacterial isolates have high potential to utilise PAHs of different molecular weights as carbon and energy sources. These identified bacteria are of special significance in their capacity to emulsify the PAHs and their ability to utilize them. Thus, they could be potentially useful for bioremediation of oil sludge and composting processes.

Keywords: bioaugmentation, biodegradation, bioremediation, composting, oil sludge, PAHs, animal manures

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Authors: James Forren

Abstract:

This research paper details a recent demonstrator project in which digital form found textile structures were built by human craftspersons wearing augmented reality (AR) head-worn displays (HWDs). The project utilized a wet-state natural fiber / cementitious matrix composite to generate minimal bending shapes in tension which, when cured and rotated, performed as minimal-bending compression members. The significance of the project is that it synthesizes computational structural simulations with visually guided handcraft production. Computational and physical form-finding methods with textiles are well characterized in the development of architectural form. One difficulty, however, is physically building computer simulations: often requiring complicated digital fabrication workflows. However, AR HWDs have been used to build a complex digital form from bricks, wood, plastic, and steel without digital fabrication devices. These projects utilize, instead, the tacit knowledge motor schema of the human craftsperson. Computational simulations offer unprecedented speed and performance in solving complex structural problems. Human craftspersons possess highly efficient complex spatial reasoning motor schemas. And textiles offer efficient form-generating possibilities for individual structural members and overall structural forms. This project proposes that the synthesis of these three modalities of structural problem-solving – computational, human, and material - may not only develop efficient structural form but offer further creative potentialities when the respective intelligence of each modality is productively leveraged. The project methodology pertains to its three modalities of production: 1) computational, 2) human, and 3) material. A proprietary three-dimensional graphic statics simulator generated a three-legged arch as a wireframe model. This wireframe was discretized into nine modules, three modules per leg. Each module was modeled as a woven matrix of one-inch diameter chords. And each woven matrix was transmitted to a holographic engine running on HWDs. Craftspersons wearing the HWDs then wove wet cementitious chords within a simple falsework frame to match the minimal bending form displayed in front of them. Once the woven components cured, they were demounted from the frame. The components were then assembled into a full structure using the holographically displayed computational model as a guide. The assembled structure was approximately eighteen feet in diameter and ten feet in height and matched the holographic model to under an inch of tolerance. The construction validated the computational simulation of the minimal bending form as it was dimensionally stable for a ten-day period, after which it was disassembled. The demonstrator illustrated the facility with which computationally derived, a structurally stable form could be achieved by the holographically guided, complex three-dimensional motor schema of the human craftsperson. However, the workflow traveled unidirectionally from computer to human to material: failing to fully leverage the intelligence of each modality. Subsequent research – a workshop testing human interaction with a physics engine simulation of string networks; and research on the use of HWDs to capture hand gestures in weaving seeks to develop further interactivity with rope and chord towards a bi-directional workflow within full-scale building environments.

Keywords: augmented reality, cementitious composites, computational form finding, textile structures

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Authors: M. N. Azian, A. N. Ilia Anisa, Y. Iwai

Abstract:

The mechanism for extraction bioactive compounds from plant matrix is essential for optimizing the extraction process. As a benchmark technique, a soxhlet extraction has been utilized for discussing the mechanism and compared with an accelerated water extraction. The trends of both techniques show that the process involves extraction and degradation. The highest yields of 6-, 8-, 10-gingerols and 6-shogaol in soxhlet extraction were 13.948, 7.12, 10.312 and 2.306 mg/g, respectively. The optimum 6-, 8-, 10-gingerols and 6-shogaol extracted by the accelerated water extraction at 140oC were 68.97±3.95 mg/g at 3min, 18.98±3.04 mg/g at 5min, 5.167±2.35 mg/g at 3min and 14.57±6.27 mg/g at 3min, respectively. The effect of temperature at 3mins shows that the concentration of 6-shogaol increased rapidly as decreasing the recovery of 6-gingerol.

Keywords: mechanism, ginger bioactive compounds, soxhlet extraction, accelerated water extraction

Procedia PDF Downloads 424

Authors: D. Zahraddeen, N. M. Lemu, P. P. Barje, I. S. R. Butswat

Abstract:

This study was conducted to investigate some of the factors affecting the optimum reproductive capacity of the indigenous breeds of sheep in Nigeria. A total of 767 sheep of different breeds were investigated. The reproductive indices considered were birth/weaning weights, litter size, parity, mortality, reproductive problems/disorders, body condition score (BCS), as well as growth traits. The results showed that litter size, parity, and BCS had significant (p < 0.05) effects on birth/weaning weights, mortality rates and growth traits of the sheep breeds studied. Similarly, the rearing method/system significantly (p < 0.05) influenced other reproductive traits such as birth/weaning weights, mortality, growth performance of lambs. However, the major reproductive problems/disorders in the ewes were dystocia (30.94%), retained placenta (16.91%), mastitis (15.83), pregnancy toxaemia (11.51%), uterine prolapse (6.48%) and vaginal prolapse (3.24%). In the rams, the incidence of reproductive problems included cryptorchidism (1.08%), orchitis (2.87%) and scrotal dermatophilosis (1.79%), among others. This study concludes that the four breeds of sheep (Balami, Yankasa, Uda, and West African Dwarf sheep) and their crosses exhibited varied genetic make-up and potentials. However, the large number of sheep farmers practicing the extensive production system might be responsible for the low reproductive performance of this species in the country. It is, therefore, recommended that significant improvement could be achieved through enhanced management practices of these animals.

Keywords: sheep, breeds, reproduction, disorders

Procedia PDF Downloads 146

Authors: Lina Fayed Amin

Abstract:

The research studied, in the beginning, the related urban concepts such as the urban, development, urban development. As it also deals with the upgrading, urban upgrading, community participation and the role of local administration in development and upgrading projects. Then it studies some regional upgrading & urban development projects in Egypt followed by international projects, and the analysis the strategies followed in dealing with these projects. Afterwards, we state the regional aspects of both Damietta governorate & city, dealing with its potentials & development constraints. Followed by studying the upgrading and urban development projects strategies in reflection to the city’s crucial problems, and the constraints that faced the upgrading & development project. Then, it studied the implementation of the project’s strategies & it provided the financial resources needed for the development project in Damietta city. Followed by the studying of the urban and human development projects in the upgrading of Damietta city, as well as analyzing the different projects &analyzing the results of these projects on the aspects of the city’s needs. Then the research analysis in comparison the upgrading and urban development project in Damietta and the regional upgrading and development projects in Egypt. As well as the comparison between the upgrading and urban development project and the international projects in some Arabic and foreign countries in relation to the goals, problems, obstacles, the community participation, the finance resources and the results. Finally, it reviews the results and recommendations that were reached as a result of studying the similar urban upgrading projects in Egypt and in some Arabic and foreign countries. Followed by the analytical analysis of the upgrading and urban development in Egypt

Keywords: Damietta city, urban development, upgrading mechanisms, urban upgrading

Procedia PDF Downloads 411

Authors: Behrooz Ghasemi, Bahram Sharijian

Abstract:

Al2O3/Mo nanocomposite powders were successfully synthesized by mechanical milling through mechanochemical reaction between MoO3 and Al. The structural evolutions of powder particles during mechanical milling were studied by X-ray diffractometry (XRD), energy dispersive X-ray spectroscopy(EDX) and scanning electron microscopy (SEM). Results show that Al2O3-Mo was completely obtained after 5 hr of milling. The crystallite sizes of Al2O3 and Mo after milling for 20 hr were about 45 nm and 23 nm, respectively. With longer milling time, the intensities of Al2O3 and Mo peaks decreased and became broad due to the decrease in crystallite size. Morphological features of powders were influenced by the milling time. The resulting Al2O3- Mo nanocomposite powder exhibited an average particle size of 200 nm after 20 hr of milling. Also nanocomposite powder after 10 hr milling had relatively equiaxed shape with uniformly distributed Mo phase in Al2O3 matrix.

Keywords: Al2O3/Mo, nanocomposites, mechanochemical, mechanical milling

Procedia PDF Downloads 357

Authors: G. Torabian, A. Fathi, P. Valtchev, F. Dehghani

Abstract:

The superior polyphenol content of Sambucus nigra berries has high health potentials for the production of nutraceutical products. Numerous factors influence the polyphenol content of the final products including the berries’ source and the subsequent processing production steps. The aim of this study is to compare the polyphenol content of berries from two different sources and also to optimise the polyphenol extraction process from elderberries. Berries from source B obtained more acceptable physical properties than source A; a single berry from source B was double in size and weight (both wet and dry weight) compared with a source A berry. Despite the appropriate physical characteristics of source B berries, their polyphenolic profile was inferior; as source A berries had 2.3 fold higher total anthocyanin content, and nearly two times greater total phenolic content and total flavonoid content compared to source B. Moreover, the result of this study showed that almost 50 percent of the phenolic content of berries are entrapped within their skin and pulp that potentially cannot be extracted by press juicing. To address this challenge and to increase the total polyphenol yield of the extract, we used cold-shock blade grinding method to break the cell walls. The result of this study showed that using cultivars with higher phenolic content as well as using the whole fruit including juice, skin and pulp can increase polyphenol yield significantly; and thus, may boost the potential of using elderberries as therapeutic products.

Keywords: different sources, elderberry, grinding, juicing, polyphenols

Procedia PDF Downloads 287

Authors: Arunava Chakrabarti

Abstract:

A one-dimensional chain of magnetic atoms, representative of a quantum gas in an artificial quasi-periodic potential and modeled by the well-known Aubry-Andre function and its variants are studied in respect of its capability of working as a spin filter for arbitrary spins. The basic formulation is explained in terms of a perfectly periodic chain first, where it is shown that a definite correlation between the spin S of the incoming particles and the magnetic moment h of the substrate atoms can open up a gap in the energy spectrum. This is crucial for a spin filtering action. The simple one-dimensional chain is shown to be equivalent to a 2S+1 strand ladder network. This equivalence is exploited to work out the condition for the opening of gaps. The formulation is then applied for a one-dimensional chain with quasi-periodic variation in the site potentials, the magnetic moments and their orientations following an Aubry-Andre modulation and its variants. In addition, we show that a certain correlation between the system parameters can generate absolutely continuous bands in such systems populated by Bloch like extended wave functions only, signaling the possibility of a metal-insulator transition. This is a case of correlated disorder (a deterministic one), and the results provide a non-trivial variation to the famous Anderson localization problem. We have worked within a tight binding formalism and have presented explicit results for the spin half, spin one, three halves and spin five half particles incident on the magnetic chain to explain our scheme and the central results.

Keywords: Aubry-Andre model, correlated disorder, localization, spin filter

Procedia PDF Downloads 350