Search results for: computational materials

Authors: Yohann R. J. Thomas, Sébastien Solan

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Conventional battery technology includes the assembly of electrode/separator/electrode by standard techniques such as stacking or winding, depending on the format size. In that type of batteries, coating or pasting techniques are only used for the electrode process. The processes are suited for large scale production of batteries and perfectly adapted to plenty of application requirements. Nevertheless, as the demand for both easier and cost-efficient production modes, flexible, custom-shaped and efficient small sized batteries is rising. Thin-film, printable batteries are one of the key areas for printed electronics. In the frame of European BASMATI project, we are investigating the feasibility of a new design of lithium-ion battery: interdigitated planar core design. Polymer substrate is used to produce bendable and flexible rechargeable accumulators. Direct fully printed batteries lead to interconnect the accumulator with other electronic functions for example organic solar cells (harvesting function), printed sensors (autonomous sensors) or RFID (communication function) on a common substrate to produce fully integrated, thin and flexible new devices. To fulfill those specifications, a high resolution printing process have been selected: Aerosol jet printing. In order to fit with this process parameters, we worked on nanomaterials formulation for current collectors and electrodes. In addition, an advanced printed polymer-electrolyte is developed to be implemented directly in the printing process in order to avoid the liquid electrolyte filling step and to improve safety and flexibility. Results: Three different current collectors has been studied and printed successfully. An ink of commercial copper nanoparticles has been formulated and printed, then a flash sintering was applied to the interdigitated design. A gold ink was also printed, the resulting material was partially self-sintered and did not require any high temperature post treatment. Finally, carbon nanotubes were also printed with a high resolution and well defined patterns. Different electrode materials were formulated and printed according to the interdigitated design. For cathodes, NMC and LFP were efficaciously printed. For anodes, LTO and graphite have shown to be good candidates for the fully printed battery. The electrochemical performances of those materials have been evaluated in a standard coin cell with lithium-metal counter electrode and the results are similar with those of a traditional ink formulation and process. A jellified plastic crystal solid state electrolyte has been developed and showed comparable performances to classical liquid carbonate electrolytes with two different materials. In our future developments, focus will be put on several tasks. In a first place, we will synthesize and formulate new specific nano-materials based on metal-oxyde. Then a fully printed device will be produced and its electrochemical performance will be evaluated.

Keywords: high resolution digital printing, lithium-ion battery, nanomaterials, solid-state electrolytes

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Authors: P. B. Sob, A. A. Alugongo, T. B. Tengen

Abstract:

The activation volume of 6082T6 aluminum is investigated at different temperatures on grain size variants. The deformation activation volume was computed on the basis of the relationship between the Boltzmann’s constant k, the testing temperatures, the material strain rate sensitivity and the material yield stress of grain size variants. The material strain rate sensitivity is computed as a function of yield stress and strain rate of grain size variants. The effect of the material strain rate sensitivity and the deformation activation volume of 6082T6 aluminum at different temperatures of 3-D grain are discussed. It is shown that the strain rate sensitivities and activation volume are negative for the grain size variants during the deformation of nanostructured materials. It is also observed that the activation volume vary in different ways with the equivalent radius, semi minor axis radius, semi major axis radius and major axis radius. From the obtained results it is shown that the variation of activation volume increased and decreased with the testing temperature. It was revealed that, increased in strain rate sensitivity led to decrease in activation volume whereas increased in activation volume led to decrease in strain rate sensitivity.

Keywords: nanostructured materials, grain size variants, temperature, yield stress, strain rate sensitivity, activation volume

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Authors: Gabrielle Peck, Ryan Hayes

Abstract:

The use of a phi meter allows for definition of equivalence ratio during a fire test. Previous phi meter designs have used expensive catalysts and had restricted portability due to the large furnace and requirement for pure oxygen. The new design of the phi meter did not require the use of a catalyst. The furnace design was based on the existing micro-scale combustion calorimetry (MCC) furnace and operating conditions based on the secondary oxidizer furnace used in the steady state tube furnace (SSTF). Preliminary tests were conducted to study the effects of varying furnace temperatures on combustion efficiency. The SSTF was chosen to validate the phi meter measurements as it can both pre-set and independently quantify the equivalence ratio during a test. The data were in agreement with the data obtained on the SSTF. It was also validated by a comparison of CO2 yields obtained from the SSTF oxidizer and those obtained by the phi meter. The phi meter designed and constructed in this work was proven to work effectively on a bench-scale. The phi meter was then used to measure the equivalence ratio on a series of large-scale ISO 9705 tests for numerous fire conditions. The materials used were a range of non-homogenous materials such as polyurethane. The measurements corresponded accurately to the data collected, showing the novel design can be used from bench to large-scale tests to measure equivalence ratio. This cheaper, more portable, safer and easier to use phi meter design will enable more widespread use and the ability to quantify fire conditions of tests, allowing for better understanding of flammability and smoke toxicity.

Keywords: phi meter, smoke toxicity, fire condition, ISO9705, novel equipment

Procedia PDF Downloads 103

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: Paulo Teodoro De Luna Carada, Toru Fujii, Kazuya Okubo

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Natural fibers have wide variety of uses (e.g., rope, paper, and building materials). One specific application of it is in the field of composite materials (i.e., green composites). Huge amount of research are being done in this field due to rising concerns in the harmful effects of synthetic materials to the environment. There are several natural fibers used in this field, one of which can be extracted from a plant called kenaf (Hibiscus cannabinus L.). Kenaf fiber is regarded as a good alternative because the plant is easy to grow and the fiber is easy to extract. Additionally, it has good properties. Treatments, which are classified as mechanical or chemical in nature, can be done in order to improve the properties of the fiber. The aim of this study is to assess the effects of heat treatment in kenaf fiber. It specifically aims to observe the effect in the tensile strength and modulus of the fiber. Kenaf fiber bundles with an average diameter of at most 100μm was used for this purpose. Heat treatment was done using a constant temperature oven with the following heating temperatures: (1) 160̊C, (2) 180̊C, and (3) 200̊C for a duration of one hour. As a basis for comparison, tensile test was first done to kenaf fibers without any heat treatment. For every heating temperature, three groups of samples were prepared. Two groups of which were for doing tensile test (one group was tested right after heat treatment while the remaining group was kept inside a closed container with relative humidity of at least 95% for two days). The third group was used to observe how much moisture the treated fiber will absorb when it is enclosed in a high moisture environment for two days. The results showed that kenaf fiber can retain its tensile strength when heated up to a temperature of 160̊C. However, when heated at a temperature of about 180̊C or higher, the tensile strength decreases significantly. The same behavior was observed for the tensile modulus of the fiber. Additionally, the fibers which were stored for two days absorbed nearly the same amount of moisture (about 20% of the dried weight) regardless of the heating temperature. Heat treatment might have damaged the fiber in some way. Additional test was done in order to see if the damage due to heat treatment is attributed to changes in the viscoelastic property of the fiber. The findings showed that kenaf fibers can be heated for at most 160̊C to attain good tensile strength and modulus. Additionally, heating the fiber at high temperature (>180̊C) causes changes in its viscoelastic property. The results of this study is significant for processes which requires heat treatment not only in kenaf fiber but might also be helpful for natural fibers in general.

Keywords: heat treatment, kenaf fiber, natural fiber, mechanical properties

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Authors: Ali Cheraghian, Farshid Hajati, Soheila Gheisari, Yongsheng Gao

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In this paper, we present a novel 2.5D face recognition method based on Gabor Discrete Cosine Transform (GDCT). In the proposed method, the Gabor filter is applied to extract feature vectors from the texture and the depth information. Then, Discrete Cosine Transform (DCT) is used for dimensionality and redundancy reduction to improve computational efficiency. The system is combined texture and depth information in the decision level, which presents higher performance compared to methods, which use texture and depth information, separately. The proposed algorithm is examined on publically available Bosphorus database including models with pose variation. The experimental results show that the proposed method has a higher performance compared to the benchmark.

Keywords: Gabor filter, discrete cosine transform, 2.5d face recognition, pose

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Authors: Junkal Gutierrez, Hernane S. Barud, Sidney J. L. Ribeiro, Agnieszka Tercjak

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Nowadays the interest on green nanocomposites and on the development of more environmental friendly products has been increased. Bacterial cellulose has been recently investigated as an attractive environmentally friendly material for the preparation of low-cost nanocomposites. The formation of cellulose by laboratory bacterial cultures is an interesting and attractive biomimetic access to obtain pure cellulose with excellent properties. Additionally, properties as molar mass, molar mass distribution, and the supramolecular structure could be control using different bacterial strain, culture mediums and conditions, including the incorporation of different additives. This kind of cellulose is a natural nanomaterial, and therefore, it has a high surface-to-volume ratio which is highly advantageous in composites production. Such property combined with good biocompatibility, high tensile strength, and high crystallinity makes bacterial cellulose a potential material for applications in different fields. The aim of this investigation work was the fabrication of novel hybrid inorganic-organic composites based on bacterial cellulose, cultivated in our laboratory, as a template. This kind of biohybrid nanocomposites gathers together excellent properties of bacterial cellulose with the ones displayed by typical inorganic nanoparticles like optical, magnetic and electrical properties, luminescence, ionic conductivity and selectivity, as well as chemical or biochemical activity. In addition, the functionalization of cellulose with inorganic materials opens new pathways for the fabrication of novel multifunctional hybrid materials with promising properties for a wide range of applications namely electronic paper, flexible displays, solar cells, sensors, among others. In this work, different pathways for fabrication of multifunctional biohybrid nanopapers with tunable properties based on BC modified with amphiphilic poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (EPE) block copolymer, sol-gel synthesized nanoparticles (titanium, vanadium and a mixture of both oxides) and functionalized iron oxide nanoparticles will be presented. In situ (biosynthesized) and ex situ (at post-production level) approaches were successfully used to modify BC membranes. Bacterial cellulose based biocomposites modified with different EPE block copolymer contents were developed by in situ technique. Thus, BC growth conditions were manipulated to fabricate EPE/BC nanocomposite during the biosynthesis. Additionally, hybrid inorganic/organic nanocomposites based on BC membranes and inorganic nanoparticles were designed via ex-situ method, by immersion of never-dried BC membranes into different nanoparticle solutions. On the one hand, sol-gel synthesized nanoparticles (titanium, vanadium and a mixture of both oxides) and on the other hand superparamagnetic iron oxide nanoparticles (SPION), Fe2O3-PEO solution. The morphology of designed novel bionanocomposites hybrid materials was investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). In order to characterized obtained materials from the point of view of future applications different techniques were employed. On the one hand, optical properties were analyzed by UV-vis spectroscopy and spectrofluorimetry and on the other hand electrical properties were studied at nano and macroscale using electric force microscopy (EFM), tunneling atomic force microscopy (TUNA) and Keithley semiconductor analyzer, respectively. Magnetic properties were measured by means of magnetic force microscopy (MFM). Additionally, mechanical properties were also analyzed.

Keywords: bacterial cellulose, block copolymer, advanced characterization techniques, nanoparticles

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Authors: Jason Ting Jing Cheng, Lee Foo Wei, Yew Ming Kun, Chin Ren Jie, Yip Chun Chieh

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The utilization of industrial by-products, such as steel slag in cementitious materials, not only mitigates environmental impact but also enhances material properties. This study investigates the dual influence of steel slag particle size on the compressive strength and carbonation efficiency of cementitious composites. Through a systematic experimental approach, steel slag particles were incorporated into cement at varying sizes, and the resulting composites were subjected to mechanical and carbonation tests. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) are conducted in this paper. The findings reveal a positive correlation between increased particle size and compressive strength, attributed to the improved interfacial transition zone and packing density. Conversely, smaller particle sizes exhibited enhanced carbonation efficiency, likely due to the increased surface area facilitating the carbonation reaction. The presence of higher silica and calcium content in finer particles was confirmed by EDX, which contributed to the accelerated carbonation process. This study underscores the importance of particle size optimization in designing sustainable cementitious materials with balanced mechanical performance and carbon sequestration potential. The insights gained from the advanced analytical techniques offer a comprehensive understanding of the mechanisms at play, paving the way for the strategic use of steel slag in eco-friendly construction practices.

Keywords: steel slag, carbonation efficiency, particle size enhancement, compressive strength

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Authors: Inci Develioglu, Hasan Firat Pulat

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Sustainable development is one of the most important topics in today's world, and it is also an important research topic for geoenvironmental engineering. Dredging process is performed to expand the river and port channel, flood control and accessing harbors. Every year large amount of sediment are dredged for these purposes. Dredged marine soils can be reused as filling materials, road and foundation embankments, construction materials and wildlife habitat developments. In this study, geotechnical engineering properties and compressibility behavior of dredged soil obtained from the Izmir Bay were investigated. The samples with four different organic matter contents were obtained and particle size distributions, consistency limits, pH and specific gravity tests were performed. The consolidation tests were conducted to examine organic matter content (OMC) effects on compressibility behavior of dredged soil. This study has shown that the OMC has an important effect on the engineering properties of dredged soils. The liquid and plastic limits increased with increasing OMC. The lowest specific gravity belonged to sample which has the maximum OMC. The specific gravity values ranged between 2.76 and 2.52. The maximum void ratio difference belongs to sample with the highest OMC (De_11% = 0.38)_. As the organic matter content of the samples increases, the change in the void ratio has also increased. The compression index increases with increasing OMC.

Keywords: compressibility, consolidation, geotechnical properties, organic matter content, dredged soil

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Authors: Vinay Kumar Vanjakula, Frank Adam, Nils Goseberg

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Wind power is one of the leading renewable energy generation methods. Due to abundant higher wind speeds far away from shore, the construction of offshore wind turbines began in the last decades. However, installation of offshore foundation-based (monopiles) wind turbines in deep waters are often associated with technical and financial challenges. To overcome such challenges, the concept of floating wind turbines is expanded as the basis from the oil and gas industry. The unfolding of Universal heavyweight gravity anchor (UGA) for floating based foundation for floating Tension Leg Platform (TLP) sub-structures is developed in this research work. It is funded by the German Federal Ministry of Education and Research) for a three-year (2019-2022) research program called “Offshore Wind Solutions Plus (OWSplus) - Floating Offshore Wind Solutions Mecklenburg-Vorpommern.” It’s a group consists of German institutions (Universities, laboratories, and consulting companies). The part of the project is focused on the numerical modeling of gravity anchor that involves to analyze and solve fluid flow problems. Compared to gravity-based torpedo anchors, these UGA will be towed and lowered via controlled machines (tug boats) at lower speeds. This kind of installation of UGA are new to the offshore wind industry, particularly for TLP, and very few research works have been carried out in recent years. Conventional methods for transporting the anchor requires a large transportation crane vessel which involves a greater cost. This conceptual UGA anchors consists of ballasting chambers which utilizes the concept of buoyancy forces; the inside chambers are filled with the required amount of water in a way that they can float on the water for towing. After reaching the installation site, those chambers are ballasted with water for lowering. After it’s lifetime, these UGA can be unballasted (for erection or replacement) results in self-rising to the sea surface; buoyancy chambers give an advantage for using an UGA without the need of heavy machinery. However, while lowering/rising the UGA towards/away from the seabed, it experiences difficult, harsh marine environments due to the interaction of waves and currents. This leads to drifting of the anchor from the desired installation position and damage to the lowering machines. To overcome such harsh environments problems, a numerical model is built to investigate the influences of different outer contours and other fluid governing shapes that can be installed on the UGA to overcome the turbulence and drifting. The presentation will highlight the importance of the Computational Fluid Dynamics (CFD) numerical model in OpenFOAM, which is open-source programming software.

Keywords: anchor lowering, towing, waves, currrents, computational fluid dynamics

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Authors: Derkaoui Orkia, Lehireche Ahmed

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The topic of this article is to exploring the potentialities of a powerful optimization technique, namely Semidefinite Programming, for solving NP-hard problems. This approach provides tight relaxations of combinatorial and quadratic problems. In this work, we solve the maximum clique problem using this relaxation. The clique problem is the computational problem of finding cliques in a graph. It is widely acknowledged for its many applications in real-world problems. The numerical results show that it is possible to find a maximum clique in polynomial time, using an algorithm based on semidefinite programming. We implement a primal-dual interior points algorithm to solve this problem based on semidefinite programming. The semidefinite relaxation of this problem can be solved in polynomial time.

Keywords: semidefinite programming, maximum clique problem, primal-dual interior point method, relaxation

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Authors: Lu-Yin Lin

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The morphology of electroactive material is highly related to energy storage ability. Structure-directing agent (SDA) can design electroactive materials with favorable surface properties. Zeolitic imidazolate framework 67 (ZIF67) is one of the potential electroactive materials for energy storage devices. The SDA concept is less applied to designing ZIF67 derivatives in previous studies. An in-situ technique with ammonium fluoride (NH₄F) as SDA is proposed to produce a ZIF67 derivative with highly improved energy storage ability. Attracted by the effective in-situ technique, the NH₄F, ammonium bifluoride (NH₄HF₂), and ammonium tetrafluoroborate (NH₄BF₄) are first used as SDA to synthesize ZIF67 derivatives in one-step solution process as electroactive material of energy storage devices. The mechanisms of forming ZIF67 derivatives synthesized with different SDAs are discussed to explain the SDA effects on physical and electrochemical properties. The largest specific capacitance (CF) of 1527.0 Fg-¹ and the capacity of 296.9 mAhg-¹ are obtained for the ZIF67 derivative prepared using NH₄BF₄ as SDA. The energy storage device composed of the optimal ZIF67 derivative and carbon electrodes presents a maximum energy density of 15.1 Whkg-¹ at the power density of 857 Wkg-¹. The CF retention of 90% and Coulombic efficiency larger than 98% are also obtained after 5000 cycles.

Keywords: ammonium bifluoride, ammonium tetrafluoroborate, energy storage device, one-step solution process, structure-directing agent, zeolitic imidazolate framework 67

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Authors: Taehan Lee

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We consider a network design problem which has shortest routing restriction based on the values determined by the installed facilities on each arc. In conventional multicommodity network design problem, a commodity can be routed through any possible path when the capacity is available. But, we consider a problem in which the commodity between two nodes must be routed on a path which has shortest metric value and the link metric value is determined by the installed facilities on the link. By this routing restriction, the problem has a distinct characteristic. We present an integer programming formulation containing the primal-dual optimality conditions to the shortest path routing. We give some computational results for the model.

Keywords: integer programming, multicommodity network design, routing, shortest path

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Authors: M. F. F. Ab Rashid, A. N. Mohd Rose, N. M. Z. Nik Mohamed, W. S. Wan Harun, S. A. Che Ghani

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Traveling salesman problem with precedence constraint (TSPPC) is one of the most complex problems in combinatorial optimization. The existing algorithms to solve TSPPC cost large computational time to find the optimal solution. The purpose of this paper is to present an efficient genetic algorithm that guarantees optimal solution with less number of generations and iterations time. Unlike the existing algorithm that generates priority factor as chromosome, the proposed algorithm directly generates sequence of solution as chromosome. As a result, the proposed algorithm is capable of generating optimal solution with smaller number of generations and iteration time compare to existing algorithm.

Keywords: traveling salesman problem, sequencing, genetic algorithm, precedence constraint

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Authors: Anna Piasek, Anna Szymkiewicz, Gabriela Wiktor, Jolanta Pulit-Prociak, Marcin Banach

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Carbon dots (CDs) have great potential for application in many fields of science. They are characterized by fluorescent properties that can be manipulated. The nanomaterial has many advantages in addition to its unique properties. CDs may be obtained easily, and they undergo surface functionalization in a simple way. In addition, there is a wide range of raw materials that can be used for their synthesis. An interesting possibility is the use of numerous waste materials of natural origin. In the research presented here, the synthesis of CDs was carried out according to the principles of Green chemistry. Beet molasses was used as a natural raw material. It has a high sugar content. This makes it an excellent high-carbon precursor for obtaining CDs. To increase the fluorescence effect, we modified the surface of CDs with silver (Ag-CDs) nanoparticles. The process of obtaining CQD was based on the hydrothermal method by applying microwave radiation. Silver nanoparticles were formed via the chemical reduction method. The synthesis plans were performed on the Design of the Experimental method (DoE). Variable process parameters such as concentration of beet molasses, temperature and concentration of nanosilver were used in these syntheses. They affected the obtained properties and particle parameters. The Ag-CDs were analyzed by UV-vis spectroscopy. The fluorescence properties and selection of the appropriate excitation light wavelength were performed by spectrofluorimetry. Particle sizes were checked using the DLS method. The influence of the input parameters on the obtained results was also studied.

Keywords: fluorescence, modification, nanosilver, molasses, Green chemistry, carbon dots

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Authors: Srikanth Korla, Mahesh Sharnangat

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Composite materials are being widely used in Aerospace, Naval, Defence and other branches of engineering applications. Studies on natural fibers is another emerging research area as they are available in abundance, and also due to their eco-friendly in nature. India being one of the major producer of coir, there is always a scope to study the possibilities of exploring coir as reinforment, and with different combinations of other elements of the composite. In present investigation effort is made to utilize properties possessed by natural fiber and make them enable with polymer/epoxy resin. In natural fiber coconut coir is used as reinforcement fiber in epoxy resin with varying weight percentages of fiber and filler material. Titanium dioxide powder (TiO2) is used as filler material with varying weight percentage including 0%, 2% and 4% are considered for experimentation. Environmental effects on the performance of the composite plate are also studied and presented in this project work; Moisture absorption test for composite specimens is conducted using different solvents including Kerosene, Mineral Water and Saline Water, and its absorption capacity is evaluated. Analysis is carried out in different combinations of Coir as fiber and TiO2 as filler material, and the best suitable composite material considering the strength and environmental effects is identified in this work. Therefore, the significant combination of the composite material is with following composition: 2% TiO2 powder 15% of coir fibre and 83% epoxy, under unique mechanical and environmental conditions considered in the work.

Keywords: composite materials, moisture test, filler material, natural fibre composites

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Authors: Manthan Patel, Vinit Ahlawat, Anshh Singh Claire, Pijush Samui

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This paper focuses on the analysis of quicksand condition for a dam foundation. The quicksand condition occurs in cohesion less soil when effective stress of soil becomes zero. In a dam, the saturated sediment may appear quite solid until a sudden change in pressure or shock initiates liquefaction. This causes the sand to form a suspension and lose strength hence resulting in failure of dam. A soil profile shows different properties at different points and the values obtained are uncertain thus reliability analysis is performed. The reliability is defined as probability of safety of a system in a given environment and loading condition and it is assessed as Reliability Index. The reliability analysis of dams under quicksand condition is carried by Gaussian Process Regression (GPR). Reliability index and factor of safety relating to liquefaction of soil is analysed using GPR. The results of reliability analysis by GPR is compared to that of conventional method and it is demonstrated that on applying GPR the probabilistic analysis reduces the computational time and efforts.

Keywords: factor of safety, GPR, reliability index, quicksand

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Authors: K. Boualem, T. Yahiaoui, A. Azzi

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Numerical investigations are performed to analyze the flow behavior over NACA0015 and to evaluate the efficiency of synthetic jet as active control device. The second objective of this work is to investigate the influence of momentum coefficient of synthetic jet on the flow behaviour. The unsteady Reynolds-averaged Navier-Stokes equations of the turbulent flow are solved using, k-ω SST provided by ANSYS CFX-CFD code. The model presented in this paper is a comprehensive representation of the information found in the literature. Comparison of obtained numerical flow parameters with the experimental ones shows that the adopted computational procedure reflects nearly the real flow nature. Also, numerical results state that use of synthetic jets devices has positive effects on the flow separation, and thus, aerodynamic performance improvement of NACA0015 airfoil. It can also be observed that the use of synthetic jet increases the lift coefficient about 13.3% and reduces the drag coefficient about 52.7%.

Keywords: active control, synthetic jet, NACA airfoil, CFD

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Authors: Leila Chebaiki-Adli, Naima Chabbi-Chemrouk

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In the Algiers context, the historical city (the old medina) was in the middle age surrounded by several residencies and gardens. They were built in the aim to spend hot days of the year. Among these later, the residences of AbdelTif and the gardens of the dey (which exist always), benefit from important criteria which increase interior comfort. Their know-how is today in trend and can give us several considerations to the architectural design and to the landscape architecture. Their particularity is seen in the built-garden interactions and the design solutions. These later let the user live with vegetation, sky and water through maximum of places in the constructions. On the basis on an aesthetic-tectonic approach, which make in evidence the architectural criteria of the two quoted cases studies (the AbdelTif residence and the gardens of the dey), we will explain in the proposed paper, some important characteristics and design solutions, which contribute strongly to the concretisation and the materialisation of a landscape architecture, and which can be used in all the Mediterranean area. The proposed aesthetic-tectonic approach is based on the fusion between interior and exterior, in the aim to distinguish syntactic criteria. The syntactic criteria correspond to: The composition and the articulation between interior and exterior spaces, the employed materials in the quoted spaces, the manifestation processes. The major finding of this study is the identification of paradigmatic processes related to the architectural design. These later reveal more figurative (direct) than expressive (no direct) way of design and creativeness. While the figurative way benefits from a high level of manifestation, the expressive one benefits from more composed and articulated materials.

Keywords: aesthetic/tectonic approach, Algiers context, design, landscape architecture

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Authors: Noelia L. Alchapar, Cláudia C. Pezzuto, Erica N. Correa

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Mitigating urban overheating is key to achieving the environmental and energy sustainability of cities. The management of the optical properties of the materials that make up the urban envelope -roofing, pavement, and facades- constitutes a profitable and effective tool to improve the urban microclimate and rehabilitate urban areas. Each material that makes up the urban envelope has a different capacity to reflect received solar radiation, which alters the fraction of solar radiation absorbed by the city. However, the paradigm of increasing solar reflectance in all areas of the city without distinguishing their relative position within the urban canyon can cause serious problems of overheating and discomfort among its inhabitants. The hypothesis that supports the research postulates that not all reflective technologies that contribute to urban radiative cooling favor the thermal comfort conditions of pedestrians to equal measure. The objective of this work is to determine to what degree the management of the optical properties of the facades modifies outdoor thermal comfort, given that the mitigation potential of materials with high reflectance in facades is strongly conditioned by geographical variables and by the geometric characteristics of the urban profile aspect ratio (H/W). This research was carried out under two climatic contexts, that of the city of Mendoza-Argentina and that of the city of Campinas-Brazil, according to the Köppen climate classification: BWk and Cwa, respectively. Two areas in two different climatic contexts (Mendoza - Argentina and Campinas - Brazil) were selected. Both areas have comparable urban morphology patterns. These areas are located in a region with low horizontal building density and residential zoning. The microclimatic conditions were monitored during the summer period with temperature and humidity fixed sensors inside vial channels. The microclimate model was simulated in ENVI-Met V5. A grid resolution of 3.5 x 3.5 x 3.5m was used for both cities, totaling an area of 145x145x30 grids. Based on the validated theoretical model, ten scenarios were simulated, modifying the height of buildings and the solar reflectivity of facades. The solar reflectivity façades ranges were: low (0.3) and high (0.75). The density scenarios range from 1th to the 5th level. The study scenarios' performance was assessed by comparing the air temperature, physiological equivalent temperature (PET), and thermal climate index (UTCI). As a result, it is observed that the behavior of the materials of the urban outdoor space depends on complex interactions. Many urban environmental factors influence including constructive characteristics, urban morphology, geographic locations, local climate, and so forth. The role of the vertical urban envelope is decisive for the reduction of urban overheating. One of the causes of thermal gain is the multiple reflections within the urban canyon, which affects not only the air temperature but also the pedestrian thermal comfort. One of the main findings of this work leads to the remarkable importance of considering both the urban warming and the thermal comfort aspects of pedestrians in urban mitigation strategies.

Keywords: materials facades, solar reflectivity, thermal comfort, urban cooling

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Authors: Viet-Hung Truong, Seung-Eock Kim

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This paper presents a robust software package for practical advanced analysis of space steel framed structures. The pre- and post-processors of the presented software package are coded in the C++ programming language while the solver is written by using the FORTRAN programming language. A user-friendly graphical interface of the presented software is developed to facilitate the modeling process and result interpretation of the problem. The solver employs the stability functions for capturing the second-order effects to minimize modeling and computational time. Both the plastic-hinge and fiber-hinge beam-column elements are available in the presented software. The generalized displacement control method is adopted to solve the nonlinear equilibrium equations.

Keywords: advanced analysis, beam-column, fiber-hinge, plastic hinge, steel frame

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Authors: Ewa Rusak, Sebastian Seget, Aleksandra Mroskowiak, Mirosław Partyka, Ewa Samulska, Julia Strózik, Anna Wilk, Przemysława Jarosz-Chobot

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Introduction: Various infections can affect children suffering from Type 1 Diabetes (T1D) because of dysfunctions of the immune system. The urinary tract and urethra of these children can be easily infected areas because of glycosuria. Aim: The microflora assessment of the urethra area of children with newly diagnosed T1D. Methods: The materials of the study were swabs taken prospectively from the urethral area of 63 children at the time of diagnosis of T1D (37 boys), then the results were correlated to the clinical parameters. In the statistical analysis, there were T student, Chi square, and U Mann-Whitney tests used. Results: The mean age was 9.4 years (6 months-17.4 years). The mean HbA1c value was 12.1% (5,6% - 20.1%). The mean value of glycosuria was 4463.2 mg/dl (0 - 9770 mg/dl). Ketoacidosis was diagnosed in 29 children (49%). The following microbial species were isolated in the collected materials: Staphylococcus epidermidis in 18 children (28.6%), Enterococcus faecalis in 17 children (27%), Candida albicans in 15 children (23.8%), coagulase-negative staphylococciin 11 children (17.5%), group B Streptococcus beta-hemolysis in 10 children (15.9%), S. aureus, E. coli, S. anginosus, C. glucuronolyticum, and A. urinae in 7 children each (11.1%), group B Streptococcus beta-hemolysis and S. hominis in 6 children each (9.5%), L. gasseri in 5 children (7.5%), C. dubliniensis in 4 children (6.3) and other, isolated cases. 2 of diagnosed patients were cultured negatively (3.2%). There were statistical correlations between the type of colonisation and patients’ sex and HbA1C value. Conclusions: It is extremely important to examine the urethral area at the time of diagnosis of T1D in order to detect inflammation and to undertake the appropriate and effective intervention.

Keywords: diabetology, skin disorders, microbiology, microflora

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Authors: Mathias Schlenk, Susanne Seibt, Sabine Rosenfeldt, Josef Breu, Stephan Foerster

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Thin liquid jets on micrometer scale play an important role in processing such as in fiber fabrication, inkjet printing, but also for sample delivery in modern synchrotron X-ray devices. In all these cases the liquid jets contain solvents and dissolved materials such as polymers, nanoparticles, fibers pigments or proteins. As liquid flow in liquid jets differs significantly from flow in capillaries and microchannels, particle localization and orientation will also be different. This is of critical importance for applications, which depend on well-defined homogeneous particle and fiber distribution and orientation in liquid jets. Investigations of particle orientation in liquid microjets of diluted solutions have been rare, despite their importance. With the arise of micro-focused X-ray beams it has become possible to scan across samples with micrometer resolution to locally analyse structure and orientation of the samples. In the present work, we used this method to scan across liquid microjets to determine the local distribution and orientation of anisotropic particles. The compromise wormlike block copolymer micelles as an example of long flexible fibrous structures, hectorite materials as a model of extended nanosheet structures, and gold nanorods as an illustration of short stiff cylinders to comprise all relevant anisotropic geometries. We find that due to the different velocity profile in the liquid jet, which resembles plug flow, the orientation of the particles which was generated in the capillary is lost or changed into non-oriented or bi-axially orientations depending on the geometrical shape of the particle.

Keywords: anisotropic particles, liquid microjets, reorientation, SAXS

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Authors: Tien S. H. Pham, Peter J. Mahon, Aimin Yu

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The detection of drug molecules by voltammetry has attracted great interest over the past years. However, many drug molecules exhibit poor electrochemical signals at common electrodes which result in low sensitivity in detection. An efficient way to overcome this problem is to modify electrodes with functional materials. Since discovered in 2004, graphene (or reduced graphene oxide) has emerged as one of the most studied two-dimensional carbon materials in condensed matter physics, electrochemistry, and so on due to its exceptional physicochemical properties. Additionally, the continuous development of technology has opened the new window for the successful fabrications of many novel graphene-based nanomaterials to serve in electrochemical analysis. This research aims to synthesize and characterize gold nanoparticle coated beta-cyclodextrin functionalized reduced graphene oxide (Au NP–β-CD–RGO) nanocomposites with highly conductive and strongly electro-catalytic properties as well as excellent supramolecular recognition abilities for the modification of electrodes. The electrochemical responses of ciprofloxacin at the as-prepared nanocomposite modified electrode was effectively amplified was much higher in comparison with that at the bare electrode. The linear concentration range was from 0.01 to 120 µM, with a detection limit of 2.7 nM using differential pulse voltammetry. Thus, Au NP–β-CD–RGO nanocomposite has great potential as an ideal material to construct sensitive sensors for the electrochemical determination of ciprofloxacin or similar antibacterial drugs in the future based on its excellent stability, selectivity, and reproducibility.

Keywords: Au nanoparticles, β-CD, ciprofloxacin, electrochemical determination, graphene based nanomaterials

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Authors: Bo Keun Lee, Doo Yeon Kwon, Ji Hoon Park, Gun Hee Lee, Ji Hye Baek, Heung Jae Chun, Young Joo Koh, Moon Suk Kim

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Thermo-responsive materials are viscoelastic materials that undergo a sol-to-gel phase transition at a specific temperature and many materials have been developed. MPEG-b-PCL (MPC) as a thermo-responsive material contained hydrophilic and hydrophobic segments and it formed an ordered crystalline structure of hydrophobic PCL segments in aqueous solutions. The ordered crystalline structure packed tightly or aggregated and finally induced an aggregated gel through intra- and inter-molecular interactions as a function of temperature. Thus, we introduced anionic and cationic groups into the end positions of the PCL chain to alter the hydrophobicity of the PCL segment. Introducing anionic and cationic groups into the PCL end position altered their solubility by changing the crystallinity and hydrophobicity of the PCL block domains. These results indicated that the properties of the end group in the hydrophobic PCL blockand the balance between hydrophobicity and hydrophilicity affect thermo-responsivebehavior of the copolymers in aqueous solutions. Thus, we concluded that determinant of the temperature-dependent thermo-responsive behavior of MPC depend on the ionic end group in the PCL block. So, we introduced zwitterionic end groups to investigate the thermo-responsive behavior of MPC. Methoxypoly(ethylene oxide) and ε-caprolactone (CL) were randomly copolymerized that introduced varying hydrophobic PCL lengths and an MPC featuring a zwitterionic sulfobetaine (MPC-ZW) at the chain end of the PCL segment. The MPC and MPC-ZW copolymers were obtained formed sol-state at room temperature when prepared as 20-wt% aqueous solutions. The solubility of MPC decreased when the PCL block was increased from molecular weight. The solubilization time of MPC-2.4k was around 20 min and MPC-2.8k, MPC-3.0k increased to 30 min and 1 h, respectively. MPC-3.6k was not solubilized. In case of MPC-ZW 3.6k, However, the zwitterion-modified MPC copolymers were solubilized in 3–5 min. This result indicates that the zwitterionic end group of the MPC-ZW diblock copolymer increased the aqueous solubility of the diblock copolymer even when the length of the hydrophobic PCL segment was increased. MPC and MPC-ZW diblock copolymers that featuring zwitterionic end groups were synthesized successfully. The sol-to-gel phase-transition was formed that specific temperature depend on the length of the PCL hydrophobic segments introduced and on the zwitterion groups attached to the MPC chain end. This result indicated that the zwitterionic end groups reduced the hydrophobicity in the PCL block and changed the solubilization. The MPC-ZW diblock copolymer can be utilized as a potential injectable drug and cell carrier.

Keywords: thermo-responsive material, zwitterionic, hydrophobic, crystallization, phase transition

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Authors: Weixiao Wei, Chris Shei

Abstract:

This paper describes Mandate of Heaven as a source of justification for the ruling regime from ancient China approximately three thousand years ago. Initially, the kings of Shang dynasty simply nominated themselves as the sons of Heaven sent to Earth to rule the common people. As the last generation of the kings became corrupted and ruled withbrutal force and crueltywhich directly caused their destruction, the successive kings of Zhou dynasty realised the importance of virtue and the provision of goods to the people. Legitimacy of the ruling regimes became rested not entirely on random allocation of the throne by an unknown supernatural force but on a foundation comprising morality and the ability to provide goods. The latter composite was picked up by the current ruling regime, the Chinese Communist Party, and became the cornerstone of its political legitimacy, also known as ‘performance legitimacy’ where economic development accounts for the satisfaction of the people in place of election and other democratic means of providing legal-rational legitimacy. Under this circumstance, it becomes important as well for the ruling party to use political rhetoric to convince people of the good performance of the government in the economy, morality, and foreign policy. Thus, we see a lot of propaganda materials in both government policy statements and international press conference announcements. The former consists mainly of important speeches made by prominent figures in Party conferences which are not only made publicly available on the government websites but also become obligatory reading materials for university entrance examinations. The later consists of announcements about foreign policies and strategies and actions taken by the government regarding foreign affairsmade in international conferences and offered in Chinese-English bilingual versions on official websites. This documentation strategy creates an impressive image of the Chinese Communist Party that is domestically competent and international strong, taking care of the people it governs in terms of economic needs and defending the country against any foreign interference and global adversities. This political discourse system comprising reading materials fully extractable from government websites also becomes excellent repertoire for teaching and researching in contemporary Chinese language, discourse and rhetoric, Chinese culture and tradition, Chinese political ideology, and Chinese-English translation. This paper aims to provide a detailed and comprehensive description of the current Chinese political discourse system, arguing about its lineage from the rhetorical convention of Mandate of Heaven in ancient China and its current concentration on serving the people in place of election, human rights, and freedom of speech. The paper will also provide guidelines as to how this discourse system and the manifestation of official documents created under this system can become excellent research and teaching materials in applied linguistics.

Keywords: mandate of heaven, Chinese communist party, performance legitimacy, serving the people, political discourse

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Authors: Akhila Konala, Jagadeeswara Reddy Vennapusa, Sujay Chattopadhyay

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The energy consumption of humankind is growing day by day due to an increase in the population, industrialization and their needs for living. Fossil fuels are the major source of energy to satisfy energy needs, which are non-renewable energy resources. So, there is a need to develop green resources for energy production and storage. Phase change materials (PCMs) derived from plants (green resources) are well known for their capacity to store the thermal energy as latent heat during their phase change from solid to liquid. This property of PCM could be used for storage of thermal energy. In this study, a composite with fatty acid (caprylic acid; M.P 15°C, Enthalpy 179kJ/kg) as a phase change material and expanded perlite as support porous matrix was prepared through direct impregnation method for thermal energy storage applications. The prepared composite was characterized using Differential scanning calorimetry (DSC), Field Emission Scanning Electron Microscope (FESEM), Thermal Gravimetric Analysis (TGA), and Fourier Transform Infrared (FTIR) spectrometer. The melting point of the prepared composite was 15.65°C, and the melting enthalpy was 82kJ/kg. The surface nature of the perlite was observed through FESEM. It was observed that there are micro size pores in the perlite surface, which were responsible for the absorption of PCM into perlite. In TGA thermogram, the PCM loss from composite was started at ~90°C. FTIR curves proved there was no chemical interaction between the perlite and caprylic acid. So, the PCM composite prepared in this work could be effective to use in temperature maintenance of buildings.

Keywords: caprylic acid, composite, phase change materials, PCM, perlite, thermal energy

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Authors: T. Martini, J. M. Martínez

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An algorithmic acceleration strategy based on quasi-Newton (or secant) methods is displayed for address the practical problem of accelerating the convergence of the Newton-Lagrange method in the case of convergence to critical multipliers. Since the Newton-Lagrange iteration converges locally at a linear rate, it is natural to conjecture that quasi-Newton methods based on the so called secant equation and some minimal variation principle, could converge superlinearly, thus restoring the convergence properties of Newton's method. This strategy can also be applied to accelerate the convergence of algorithms applied to fixed-points problems. Computational experience is reported illustrating the efficiency of this strategy to solve fixed-point problems with linear convergence rate.

Keywords: algorithmic acceleration, fixed-point problems, nonlinear programming, quasi-newton method

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Authors: R. P. Naik, A. K. Rakshit

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In recent years, with the rapid development in science and technology, people have increasing requirements on uses of clothing for new functions, which contributes to opportunities for further development and incorporation of new technologies along with novel materials. In this context, textiles are of fast decalescence or fast heat radiation media as per as comfort accountability of textile articles are concern. The microstructure and texture of textiles play a vital role in determining the heat-moisture comfort level of the human body because clothing serves as a barrier to the outside environment and a transporter of heat and moisture from the body to the surrounding environment to keep thermal balance between body heat produced and body heat loss. The main bottleneck which is associated with textile materials to be successful as thermal insulation materials can be enumerated as; firstly, high loft or bulkiness of material so as to provide predetermined amount of insulation by ensuring sufficient trapping of air. Secondly, the insulation depends on forced convection; such convective heat loss cannot be prevented by textile material. Third is that the textile alone cannot reach the level of thermal conductivity lower than 0.025 W/ m.k of air. Perhaps, nano-fibers can do so, but still, mass production and cost-effectiveness is a problem. Finally, such high loft materials for thermal insulation becomes heavier and uneasy to manage especially when required to carry over a body. The proposed works aim at developing lightweight effective thermal insulation textiles in combination with nanoporous silica-gel which provides the fundamental basis for the optimization of material properties to achieve good performance of the clothing system. This flexible nonwoven silica-gel composites fabric in intact monolith was successfully developed by reinforcing SiO2-gel in thermal bonded nonwoven fabric via sol-gel processing. Ambient Pressure Drying method is opted for silica gel preparation for cost-effective manufacturing. The formed structure of the nonwoven / SiO₂ -gel composites were analyzed, and the transfer properties were measured. The effects of structure and fibre on the thermal properties of the SiO₂-gel composites were evaluated. Samples are then tested against untreated samples of same GSM in order to study the effect of SiO₂-gel application on various properties of nonwoven fabric. The nonwoven fabric composites reinforced with aerogel showed intact monolith structure were also analyzed for their surface structure, functional group present, microscopic images. Developed product reveals a significant reduction in pores' size and air permeability than the conventional nonwoven fabric. Composite made from polyester fibre with lower GSM shows lowest thermal conductivity. Results obtained were statistically analyzed by using STATISTICA-6 software for their level of significance. Univariate tests of significance for various parameters are practiced which gives the P value for analyzing significance level along with that regression summary for dependent variable are also studied to obtain correlation coefficient.

Keywords: silica-gel, heat insulation, nonwoven fabric, thermal barrier clothing

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Authors: S. Nakayama

Abstract:

For non-native English speakers, using English modal auxiliary verbs appropriately can be among the most challenging tasks. This research sought to identify differences in modal verb usage between Japanese non-native English speakers (JNNS) and native speakers (NS) from two different perspectives: frequency of use and distribution of verb phrase structures (VPS) where modal verbs occur. This study can contribute to the identification of JNNSs' interlanguage with regard to modal verbs; the main aim is to make a suggestion for the improvement of teaching materials as well as to help language teachers to be able to teach modal verbs in a way that is helpful for learners. To address the primary question in this study, usage of nine central modals (‘can’, ‘could’, ‘may’, ‘might’, ‘shall’, ‘should’, ‘will’, ‘would’, and ‘must’) by JNNS was compared with that by NSs in the International Corpus Network of Asian Learners of English (ICNALE). This corpus is one of the largest freely-available corpora focusing on Asian English learners’ language use. The ICNALE corpus consists of four modules: ‘Spoken Monologue’, ‘Spoken Dialogue’, ‘Written Essays’, and ‘Edited Essays’. Among these, this research adopted the ‘Written Essays’ module only, which is the set of 200-300 word essays and contains approximately 1.3 million words in total. Frequency analysis revealed gaps as well as similarities in frequency order. Specifically, both JNNSs and NSs used ‘can’ with the most frequency, followed by ‘should’ and ‘will’; however, usage of all the other modals except for ‘shall’ was not identical to each other. A log-likelihood test uncovered JNNSs’ overuse of ‘can’ and ‘must’ as well as their underuse of ‘will’ and ‘would’. VPS analysis revealed that JNNSs used modal verbs in a relatively narrow range of VPSs as compared to NSs. Results showed that JNNSs used most of the modals with bare infinitives or the passive voice only whereas NSs used the modals in a wide range of VPSs including the progressive construction and the perfect aspect, both of which were the structures where JNNSs rarely used the modals. Results of frequency analysis suggest that language teachers or teaching materials should explain other modality items so that learners can avoid relying heavily on certain modals and have a wide range of lexical items to reflect their feelings more accurately. Besides, the underused modals should be more stressed in the classroom because they are members of epistemic modals, which allow us to not only interject our views into propositions but also build a relationship with readers. As for VPSs, teaching materials should present more examples of the modals occurring in a wide range of VPSs to help learners to be able to express their opinions from a variety of viewpoints.

Keywords: corpus linguistics, Japanese learners of English, modal auxiliary verbs, International Corpus Network of Asian Learners of English

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