Search results for: critical raw materials

Authors: Meriem Hamla, Mohamed Benaicha, Sabrine Derbal

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In the present work, several materials such as M/glass (M = Pt, Mo) were investigated to test their suitability for studying the early nucleation stages and growth of copper-tin clusters. It was found that most of these materials stand as good substrates to be used in the study of the nucleation and growth of electrodeposited Cu-Sn alloys from aqueous solution containing CuCl2, SnCl2 as electroactive species and Na3C6H5O7 as complexing agent. Among these substrates, Pt shows instantaneous models followed by 3D diffusion-limited growth. On the other hand, the electrodeposited copper-tin thin films onto Mo substrate followed progressive nucleation. The deposition mechanism of the Cu-Sn films has been studied using stationary electrochemical techniques (cyclic voltammetery (CV) and chronoamperometry (CA). The structural, morphological and compositional of characterization have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and EDAX techniques respectively.

Keywords: electrodeposition, CuSn, nucleation, mechanism

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Authors: Lukman O. Alimi, Vincent J. Smith, Leonard J. Barbour

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The thermosalient effect is an extremely rare propensity of certain crystalline solids for self-actuation by elastic deformation or a ballistic event1. Thermosalient compounds, colloquially known as ‘jumping crystals’ are promising materials for fabrication of actuators that are also being considered as materials for clean energy conversion because of their capabilities to convert thermal energy into mechanical motion directly. Herein, an organic aminonitrile and its derivatives have been probed by a combination of structural, microscopic and thermoanalytical techniques. Crystals of these compounds were analysed by means of single crystal XRD and hotstage microscopy in the temperature range of 100 to 298 K and found to exhibit the thermosalient effect. We also carried out differential scanning calorimetric analysis at the temperature corresponding to that at which the crystal jumps as observed under a hotstage microscope.

Keywords: aminonitrile, jumping crystal, self actuation, thermosalient effect

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Authors: Mohammad Mirzaei

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The term "modernism" is at the heart of debates about 20th-century literature and critical theory. Astradur Eysteinsson argues here that the notion of modernity does not emerge directly from the literature it encompasses but is actually a product of critical practices related to non-traditional literature. By intervening in and relating them to modernist works and contemporary literary theories, Esteinsson takes a comprehensive look at the idea of modernity. Eysteinsson critically examines various expressions of modernism in the rich spectrum of American, British, and European literature, criticism, and theory. He first explored a number of modernist paradigms and found a conflict between modernism's potential for cultural subversion and its relatively conservative status as a formalist project. In turn, he sees these paradigms as interpretations and inventions of literary history. Seen in this way, modernism presents both a historical change in the literary scene and the context of this change. Imbued with the connotations of tradition and modernity, modernity fulfills its primary function. Highlights and defines the complex relationship between history and post-realist literature. Eysteinsson focuses on how concepts of modernism guide our understanding of literature and literary history and how they influence the evaluation of experimental and 3post realist works in literature and art. He discusses in detail the relationship between modernism and the key terms postmodernism, avant-garde, and realism. In staging a crisis of subject and reference, modernity is not a form of discourse but its subversion, the "other" that may reveal important aspects of our social and linguistic experience in Western culture.

Keywords: literature, modernism, western cultures, postmodernism

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Authors: Gamalath M. B. P. Abeysekara

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Primary objective of any organization is to enhance the bottom line profit. Strategic procurement is one of the prominent aspects in view of receiving this ultimate objective. Strategic procurement is an activity used in each and every organization in their operations. Pharmaceutical procurement is an especially significant task for any organizations, particularly state sector concerned. The whole pharmaceutical procurement requirement of the country is procured through the State Pharmaceutical Corporation (SPC) of Sri Lanka. They follow Pharmaceutical Procurement Guideline of 2006 as the procurement principle. The main objective of this project is to identify the importance of State Pharmaceutical Corporation supplier selection criteria and critical analysis of pharmaceutical procurement procedure. State Pharmaceutical Corporations applied net price, product quality, past performance, and delivery of suppliers’ as main criteria for the selection suppliers. Data collection for this study was taken place through a questionnaire, given to fifty doctors within the Colombo district attached to five main state hospitals. Data analysis is carried out with mean and standard deviation functions. The ultimate outcomes indicated product quality, net price, and delivery of suppliers’ are the most important criteria behind the selection of suppliers. Critical analysis proved State Pharmaceutical Corporation should focus on net price reduction, improving laboratory testing facilities and effective communication between up and down stream of supply chain.

Keywords: government procurement procedure, pharmaceutical procurement supplier selection criteria, importance of SPC supplier selection criteria

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Authors: D. Olszewska, J. Niewiedzial

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In some types of Li-ion batteries carbon in the form of graphite is used. Unfortunately, carbon materials, in particular graphite, have very good electrochemical properties, but increase their volume during charge/discharge cycles, which may even lead to an explosion of the cell. The cell element may be replaced by a composite material consisting of lithium-titanium oxide Li4Ti5O12 (LTO) modified with copper and nickel ions and carbon derived from sucrose. This way you can improve the conductivity of the material. LTO is appropriate only for applications which do not require high energy density because of its high operating voltage (ca. 1.5 V vs. Li/Li+). Specific capacity of Li4Ti5O12 is high enough for utilization in Li-ion batteries (theoretical capacity 175 mAh·g-1) but it is lower than capacity of graphite anodes. Materials based on Li4Ti5O12 do not change their volume during charging/discharging cycles, however, LTO has low conductivity. Another positive aspect of the use of sucrose in the carbon composite material is to eliminate the addition of carbon black from the anode of the battery. Therefore, the proposed materials contribute significantly to environmental protection and safety of selected lithium cells. New anode materials in order to obtain Li3.8Cu0.1Ni0.1Ti5O12 have been prepared by solid state synthesis using three-way: i) stoichiometric composition of Li2CO3, TiO2, CuO, NiO (A- Li3.8Cu0.1Ni0.1Ti5O12); ii) stoichiometric composition of Li2CO3, TiO2, Cu(NO3)2, Ni(NO3)2 (B-Li3.8Cu0.1Ni0.1Ti5O12); and iii) stoichiometric composition of Li2CO3, TiO2, CuO, NiO calcined with 10% of saccharose (Li3.8Cu0.1Ni0.1Ti5O12-C). Structure of materials was studied by X-ray diffraction (XRD). The electrochemical properties were performed using appropriately prepared cell Li|Li+|Li3.8Cu0.1Ni0.1Ti5O12 for cyclic voltammetry and discharge/charge measurements. The cells were periodically charged and discharged in the voltage range from 1.3 to 2.0 V applying constant charge/discharge current in order to determine the specific capacity of each electrode. Measurements at various values of the charge/discharge current (from C/10 to 5C) were carried out. Cyclic voltammetry investigation was carried out by applying to the cells a voltage linearly changing over time at a rate of 0.1 mV·s-1 (in the range from 2.0 to 1.3 V and from 1.3 to 2.0 V). The XRD method analyzes show that composite powders were obtained containing, in addition to the main phase, 4.78% and 4% TiO2 in A-Li3.8Cu0.1Ni0.1O12 and B-Li3.8Cu0.1Ni0.1O12, respectively. However, Li3.8Cu0.1Ni0.1O12-C material is three-phase: 63.84% of the main phase, 17.49 TiO2 and 18.67 Li2TiO3. Voltammograms of electrodes containing materials A-Li3.8Cu0.1Ni0.1O12 and B-Li3.8Cu0.1Ni0.1O12 are correct and repeatable. Peak cathode occurs for both samples at a potential approx. 1.52±0.01 V relative to a lithium electrode, while the anodic peak at potential approx. 1.65±0.05 V relative to a lithium electrode. Voltammogram of Li3.8Cu0.1Ni0.1Ti5O12-C (especially for the first measurement cycle) is not correct. There are large variations in values of specific current, which are not characteristic for materials LTO. From the point of view of safety and environmentally friendly production of Li-ion cells eliminating soot and applying Li3.8Cu0.1Ni0.1Ti5O12-C as an active material of an anode in lithium-ion batteries seems to be a good alternative to currently used materials.

Keywords: anode, Li-ion batteries, Li₄O₅O₁₂, spinel

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Authors: Addharu Eri, Ningsih P. Lestari, Setyorini Adheliya, Syaiputri Khaidifah

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Rawa Pening is a lake at the Ambarawa Basin in Central Java, Indonesia. It serves as a source of power (hydroelectricity), irrigation, and flood control. The potential of this lake is getting worse by the presence of aquatic plants (Eichhornia crassipes) that grows wild, and it can make the lake covered by the cumulation of rotten E. crassipes. This cumulation causes the sediment formation which has high organic material composition. Sediment formation will be lead into a shallowing of the lake and affect water’s quality. The deposition of organic material produces methane gas and hydrogen sulfide, which in rain would turn the water muddy and decompose. Decomposition occuring in the water due to microbe activity in lake's water. The shallowing of Rawa Pening Lake not only will physically can reduce water discharge, but it also has ecologically major impact on water organism. The condition of Rawa Pening Lake peats can not be considered as unimportant issue. One of the solutions that can be applied is by using the peats as a compound materials on growing horticultural crops because the organic materials content on the mineral soil is low, particularly on an old soils. The horticultural crops required organic materials for growth promoting. The horticultural crops that use in this research is mustard cabbage (Brassica sp.). Using Rawa Pening's peats as the medium of plants with high organic materials that also can ameliorate soil’s physical properties, and indirectly serves as soil conditioner. Research will be focus on the peat’s contents and mustard cabbage product’s content. The contents that will be examined is the N-available, Ca, Mg, K, P, and C-organic. The analysis of Ca, Mg, and K is use soil base saturation measurement method and extracting soil is use NH4OAC solution. The aim of this study is to use the peats of Rawa Pening Lake as soil conditioner and increase the productivity of Brassica sp.

Keywords: Brassica sp., peats, rawa pening lake, soil conditioner

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Authors: Kitda Praraththajariya

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The main purpose of this research was to study how to communicate the identity of the Mueang district, Samut Songkram province for ecotourism. The qualitative data was collected through studying related materials, exploring the area, in-depth interviews with three groups of people: three directly responsible officers who were key informants of the district, twenty foreign tourists and five Thai tourist guides. A content analysis was used to analyze the qualitative data. The two main findings of the study were as follows: 1. The identity of Amphur (District) Mueang, Samut Songkram province. This establishment was near the Mouth of Maekong River for normal people and tourists, consisting of rest accommodations. There are restaurants where food and drinks are served, rich mangrove forests, Hoy Lod (Razor Clam) and mangrove trees. Don Hoy Lod, is characterized by muddy beaches, is a coastal wetland for Ramsar Site. It is at 1099th ranging where the greatest number of Hoy Lod (Razor Clam) can be seen from March to May each year. 2. The communication of the identity of Amphur Mueang, Samut Songkram province which the researcher could find and design to present in English materials can be summed up in 4 items: 1) The history of Amphur Mueang, Samut Songkram province 2) Wat Phet Samut Worrawihan 3) The Learning source of Ecotourism: Don Hoy Lod and Mangrove forest 4) How to keep Amphur Mueang, Samut Songkram province for ecotourism.

Keywords: foreigner tourists, signified, semiotics, ecotourism

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Authors: D. Korsacilar, C. Atas

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In this study, first thermoplastic composite materials/plates that have high ballistic impact resistance were produced. For this purpose, the thermoplastic prepreg and the vacuum bagging technique were used to produce a composite material. Thermoplastic prepregs (resin-impregnated fiber) that are supplied ready to be used, namely high-density polyethylene (HDPE) was chosen as matrix and unidirectional glass fiber was used as reinforcement. In order to compare the fiber configuration effect on mechanical properties, unidirectional and biaxial prepregs were used. Then the microstructural properties of the composites were investigated with scanning electron microscopy (SEM) analysis. Impact properties of the composites were examined by Charpy impact test and tensile mechanical tests and then the effects of ultraviolet irradiation were investigated on mechanical performance.

Keywords: ballistic, composite, thermoplastic, prepreg

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Authors: Viney Dixit, Rohit R. Shahi, Ashish Bhatnagar, P. Jain, T. P. Yadav, O. N. Srivastava

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Carbons are being widely investigated as hydrogen storage material owing to their light weight, fast hydrogen absorption kinetics and low cost. However, these materials suffer from low hydrogen storage capacity at room temperature. The aim of the present study is to synthesize carbon based material which shows moderate hydrogen storage at room temperature. For this purpose, hydrogenation characteristics of natural precursor coconut kernel is studied in this work. The hydrogen storage measurement reveals that the as-synthesized materials have good hydrogen adsorption and desorption capacity with fast kinetics. The synthesized material absorbs 8 wt.% of hydrogen at liquid nitrogen temperature and 2.3 wt.% at room temperature. This could be due to the presence of certain elements (KCl, Mg, Ca) which are confirmed by TEM.

Keywords: coconut kernel, carbonization, hydrogenation, KCl, Mg, Ca

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Authors: Rajiv Kumar Srivastava

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Manufacturing of complex products such as automobiles and computers requires a very large number of parts and sub-assemblies. The design of mechanisms for delivery of these materials to the point of assembly is an important manufacturing system and supply chain challenge. Different approaches to this problem have been evolved for assembly lines designed to make large volumes of standardized products. However, contemporary assembly systems are required to concurrently produce a variety of products using approaches such as mixed model production, and at times even mass customization. In this paper we examine the material supply approaches for variety production in moderate to large volumes. The conventional approach for material delivery to high volume assembly lines is to supply and stock materials line-side. However for certain materials, especially when the same or similar items are used along the line, it is more convenient to supply materials in kits. Kitting becomes more preferable when lines concurrently produce multiple products in mixed model mode, since space requirements could increase as product/ part variety increases. At times such kits may travel along with the product, while in some situations it may be better to have delivery and station-specific kits rather than product-based kits. Further, in some mass customization situations it may even be better to have a single delivery and assembly station, to which an entire kit is delivered for fitment, rather than a normal assembly line. Finally, in low-moderate volume assembly such as in engineered machinery, it may be logistically more economical to gather materials in an order-specific kit prior to launching final assembly. We have studied material supply mechanisms to support assembly systems as observed in case studies of firms with different combinations of volume and variety/ customization. It is found that the appropriate approach tends to be a hybrid between direct line supply and different kitting modes, with the best mix being a function of the manufacturing and supply chain environment, as well as space and handling considerations. In our continuing work we are studying these scenarios further, through the use of descriptive models and progressing towards prescriptive models to help achieve the optimal approach, capturing the trade-offs between inventory, material handling, space, and efficient line supply.

Keywords: assembly systems, kitting, material supply, variety production

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Authors: Lethola Tshikose, Munyaradzi Katurura

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Information and Communication Technology (ICT) plays a critical role in improving daily healthcare processes. The South African healthcare organizations have adopted Information Systems to integrate their patient records. This has made it much easier for healthcare organizations because patient information can now be accessible at any time. The primary purpose of this research study was to investigate the best practices that can be applied to enhance patient security and confidentiality when using e-health systems in South Africa. Security and confidentiality are critical in healthcare organizations as they ensure safety in EHRs. The research study used an inductive research approach that included a thorough literature review; therefore, no data was collected. The research paper’s scope included patient data and possible security threats associated with healthcare systems. According to the study, South African healthcare organizations discovered various patient data security and confidentiality issues. The study also revealed that when it comes to handling patient data, health professionals sometimes make mistakes. Some may not be computer literate, which posed issues and caused data to be tempered with. The research paper recommends that healthcare organizations ensure that security measures are adequately supported and promoted by their IT department. This will ensure that adequate resources are distributed to keep patient data secure and confidential. Healthcare organizations must correctly use standards set up by IT specialists to solve patient data security and confidentiality issues. Healthcare organizations must make sure that their organizational structures are adaptable to improve security and confidentiality.

Keywords: E-health, EHR, security, confidentiality, healthcare

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Authors: A. Yonetken, A. Erol, M. Cakmakkaya

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Intermetallic materials are among advanced technology materials that have outstanding mechanical and physical properties for high temperature applications. Especially creep resistance, low density and high hardness properties stand out in such intermetallics. The microstructure, mechanical properties of %88Ni-%10Cr and %2Mn powders were investigated using specimens produced by tube furnace sintering at 900-1300°C temperature. A composite consisting of ternary additions, a metallic phase, Fe ,Cr and Mn have been prepared under Ar shroud and then tube furnace sintered. XRD, SEM (Scanning Electron Microscope), were investigated to characterize the properties of the specimens. Experimental results carried out for composition %88Ni-%10Cr and %2Mn at 1300°C suggest that the best properties as 138,80HV and 6,269/cm3 density were obtained at 1300°C.

Keywords: composite, high temperature, intermetallic, sintering

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Authors: Qiong Tian, Lifeng Zhang, Demei Yu, Ajit D. Kelkar

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Low specific weight and high strength is the basic requirement for aerospace materials. Fiber-reinforced epoxy resin composites are attractive materials for this purpose. Boron nitride nanoparticles (BNNPs) have good radiation shielding capacity, which is very important to aerospace materials. Herein a processing route for an advanced hybrid composite material is demonstrated by introducing dispersed BNNPs in standard prepreg manufacturing. The hybrid materials contain three parts: E-fiberglass, an aerospace-grade epoxy resin system, and BNNPs. A vacuum assisted resin transfer molding (VARTM) was utilized in this processing. Two BNNP functionalization approaches are presented in this study: (a) covalent functionalization with 3-aminopropyltriethoxysilane (KH-550); (b) non-covalent functionalization with cetyltrimethylammonium bromide (CTAB). The functionalized BNNPs were characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction(XRD) and scanning electron microscope (SEM). The results showed that BN powder was successfully functionalized via the covalent and non-covalent approaches without any crystal structure change and big agglomerate particles were broken into platelet-like nanoparticles (BNNPs) after functionalization. Compared to pristine BN powder, surface modified BNNPs could result in significant improvement in mechanical properties such as tensile, flexural and compressive strength and modulus. CTAB functionalized BNNPs (CTAB-BNNPs) showed higher tensile and flexural strength but lower compressive strength than KH-550 functionalized BNNPs (KH550-BNNPs). These reinforcements are mainly attributed to good BNNPs dispersion and interfacial adhesion between epoxy matrix and BNNPs. This study reveals the potential in improving mechanical properties of BNNPs-containing composites laminates through surface functionalization of BNNPs.

Keywords: boron nitride, epoxy, functionalization, prepreg, composite

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Authors: Lukumba Phiri, Simon Tembo, Kumbuso Joshua Nyoni

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In Zambia recent initiatives by various power operators like ZESCO, CEC, and consumers like the mines to upgrade power systems into smart grids target an even tighter integration with information technologies to enable the integration of renewable energy sources, local and bulk generation, and demand response. Thus, for the reliable operation of smart grids, its information infrastructure must be secure and reliable in the face of both failures and cyberattacks. Due to the nature of the systems, ICS/SCADA cybersecurity and governance face additional challenges compared to the corporate networks, and critical systems may be left exposed. There exist control frameworks internationally such as the NIST framework, however, there are generic and do not meet the domain-specific needs of the SCADA systems. Zambia is also lagging in cybersecurity awareness and adoption, therefore there is a concern about securing ICS controlling key infrastructure critical to the Zambian economy as there are few known facts about the true posture. In this paper, we introduce a stochastic Edged-based Anomaly Detection for SCADA systems (SEADS) framework for threat modeling and risk assessment. SEADS enables the calculation of steady-steady probabilities that are further applied to establish metrics like system availability, maintainability, and reliability.

Keywords: anomaly, availability, detection, edge, maintainability, reliability, stochastic

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Authors: Mnasri Faiza, El Ganaoui Mohammed, Khelifa Mourad, Gabsi Slimane

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The main objective of this paper is to describe the hydrothermal behavior through porous material of construction due to temperature gradient. The construction proposed a bi-layer structure which composed of two different materials. The first is a bio-sourced panel named IBS-AKU (inertia system building), the second is the Neopor material. This system (IBS-AKU Neopor) is developed by a Belgium company (Isohabitat). The study suggests a multi-layer structure of the IBS-AKU panel in one dimension. A numerical method was proposed afterwards, by using the finite element method and a refined mesh area to strong gradients. The evolution of temperature fields and the moisture content has been processed.

Keywords: heat transfer, moisture diffusion, porous media, composite IBS-AKU, simulation

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Authors: Talita Cavaignac

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Adorno's critique of totality, especially in a split society marked by reification, also rests on the impossibility of generalizing normative principles. Given the unfeasibility of normative universalizations, which conditions can justify the possibility of criticism and normativity in Adorno's thought? If reason itself is still entangled in alienation from the model of the domination of nature, how could be possible a critical theory? In political terms, if the notion of totality is challenged by the critique of identity, how can Adorno maintain the ideal of liberation and reconciliation between private interests and the possibility of some sort of ethics without giving up a materialist theory of society and without betting in a necessary link between redemption and history? Faced with this complex of questions, it is intended to reflect on the sense in which the notion of ‘suffering’ could throw help to the epistemological problem of the foundations of criticism in Adorno's work. The idea is that, in contrast to a universalizable model of justice, Adorno mobilizes in the notion of ‘suffering’ a gateway to the critical reflection of society. He would thus develop an approach to moral problems through the sensual-bodily perspective, fear, pain, and somatic factors. Nevertheless, due to the attention to the damaged experience and to the constitution of subjectivity -a sense in which the concept of mimesis continues to stand out- we understand suffering as an expression of an objective reification. Following the statement of other authors, the intention is to think how the resources linked to the idea of ‘suffering’ in Adorno's writings are engaged in the reflection of the problem of morality and of the contradictions between universal and particular (articulated in Hegel's tradition).

Keywords: ethics, morality, sensitive, Theodor Adorno

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Authors: Koboro J. Selala

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Whilst the system of collective bargaining is well-researched in South Africa, recent studies reveal that this is an area of law and practice that is poorly understood. Despite the growing attention being paid by most scholars to the role of collective bargaining in the labour relations system, only a handful of the studies have considered collective bargaining as a mechanism of dispute resolution. The purpose of this paper is to provide a critical analysis of the current understanding of the right to engage in collective bargaining in South Africa to assess the extent to which collective bargaining is used to resolve labour disputes. The overall objective is to offer a deeper understanding of the role of collective bargaining in dispute resolution process within the South African constitutional labour law context. To this end, the paper examines the applicable legal framework of collective bargaining to address two fundamental questions that are critical to the proper understanding of the functioning of the South African collective labour dispute resolution system. The first concerns the extent to which the current South African legislative framework supports the fundamental labour rights entrenched in the Constitution of the Republic of South Africa. The second addresses the role of trade unions in collective dispute resolution processes and the extent to which they can best utilize collective bargaining to resolve labour disputes. Finally, the paper discusses the general implications of the findings to stimulate further research and to enhance the constitutional development of collective labour rights in South Africa.

Keywords: collective bargaining, constitution, freedom of association, labour relations act

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Authors: Abdelmessih Malak Sadek Labib

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The Stability in harsh environments thanks to excellent electrical, mechanical and thermal properties is what ceramics are all about selected materials for many applications despite advent of new materials such as plastics and composites. However, ceramic materials have disadvantages, including brittleness. Fragility is often attributed to pottery strong covalent and ionic bonds in the ceramic body. There is still much to learn about brittle cracks in a attention to detail, hence the fragility of the ceramic and its catastrophic failure of a frequently studied topic, particularly in charging applications. One of the most commonly used ceramics for load-bearing applications such as veneers is porcelain. Porcelain is a type of traditional pottery. Traditional pottery consists mainly of three basic ingredients: clay, which gives plasticity; silica which maintains the shape and stability of the ceramic body over temperature high temperature; and feldspar affecting glazing. In traditional pottery, the inversion of quartz during cooling the process can create microcracks that act as a stress concentration centers. Consequently, subcritical crack growth is caused due to quartz inversion origins unpredictable catastrophic failure of the work of ceramic bodies when reloading. In the case of porcelain, however, this is what the mullite hypothesis says the strength of porcelain can be significantly increased with felt Interlocking of mullite needles in the ceramic body.in this way realistic assessment of the role of quartz and mullite Porcelain with a strength of is needed to grow stronger and smaller fragile porcelain. Currently,the lack of reports on Young's moduli in the literature leads to erroneous conclusions in this regard mechanical behavior of porcelain. Therefore, the current project uses the Young's modulus approach for the investigation the role of quartz and mullite on the mechanical strength of various porcelains, in addition to reducing particle size, flexural strength fractographic forces and techniques.

Keywords: materials, technical, ceramics, properties, thermal, stability, advantages

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Authors: Saeedeh Bakhtiari, Johannes Depessemier, Stijn Hertelé, Wim De Waele

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High cycle fatigue comprising up to 10⁷ load cycles has been the subject of many studies, and the behavior of many materials was recorded adequately in this regime. However, many applications involve larger numbers of load cycles during the lifetime of machine components. In this ultra-high cycle regime, other failure mechanisms play, and the concept of a fatigue endurance limit (assumed for materials such as steel) is often an oversimplification of reality. When machine component design demands a high geometrical complexity, cast iron grades become interesting candidate materials. Grey cast iron is known for its low cost, high compressive strength, and good damping properties. However, the ultra-high cycle fatigue behavior of cast iron is poorly documented. The current work focuses on the ultra-high cycle fatigue behavior of EN-GJL-250 (GG25) grey cast iron by developing an ultrasonic (20 kHz) fatigue testing system. Moreover, the testing machine is instrumented to measure the temperature and the displacement of  the specimen, and to control the temperature. The high resonance frequency allowed to assess the  behavior of the cast iron of interest within a matter of days for ultra-high numbers of cycles, and repeat the tests to quantify the natural scatter in fatigue resistance.

Keywords: GG25, cast iron, ultra-high cycle fatigue, ultrasonic test

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Authors: Isheanesu Hungwe, Munyaradzi Shumba, Tichaona Nharingo

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High levels of nitrates in drinking water present a potential risk to human health for it is responsible for methemoglobinemia in infants. It also gives rise to eutrophication of dams and rivers. It is, therefore, important to find ways of compating the increasing amount of nitrates in the environment. This study explored the bioremediation of nitrates from aqueous solution using Brachystegia spiciformis leaf powder (BSLP). The acid treated leaf powder was characterized using FTIR and SEM before and after nitrate biosorption and desorption experiments. Critical biosorption factors, pH, contact time and biomass dosage were optimized as 4, 30 minutes and 10 g/L respectively. The equilibrium data generated from the investigation of the effect of initial nitrate ion concentration fitted the isotherm models in the order Dudinin-Radushkevich < Halsey=Freundlich < Langmuir < Temkin model based on the correlation of determination (R2). The Freundlich’s adsorption intensity and Langmuir’s separation factors revealed the favorability of nitrate ion sorption onto BSLP biomass with maximum sorption capacity of 87.297 mg/g. About 95% of the adsorbed nitrate was removed from the biomass under alkaline conditions (pH 11) proving that the regeration of the biomass, critical in sorption-desorption cycles, was possible. It was concluded that the BSLP was a multifunctional group material characterised by both micropores and macropores that could be effectively utilised in nitrate ion removal from aqueous solutions.

Keywords: adsorption, brachystegia spiciformis, methemoglobinemia, nitrates

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Authors: Hlabishi Peter Ntloana

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This paper aims to present the effectiveness of the Spatial Planning and Land Use Management Act, 2013, in addressing key spatial challenges in Fetakgomo Tubatse Local Municipality, mainly focusing on Apel nodal point. Spatial Planning and Land Use Management Act, 2013, popularly known as SPLUMA, aimed at addressing emerging and existing spatial planning and land use management challenges in South Africa. There are critical key spatial challenges that are continuously encountered in Apel Nodal Point, which include dispersed rural settlement mainly in a communal settlement. The spatial patterns and rural settlements development patterns are a challenge, and such results in uncoordinated human settlements. The objective of this research paper is to analyze the spatial planning of Apel nodal points and determine the effectiveness of the SPLUMA policy. Key Informant interviews were conducted with 20 participants, and also the municipal Spatial Development Framework was considered to explore more challenges and proposed recommendations. The results divulged that there is a huge gap in addressing spatial planning, mainly in rural areas, and correlation with the findings of the Municipal Spatial Development framework. In conclusion, spatial planning remains a critical dilemma in most rural settlements, and there must be programmes and strategies to balance the effectiveness of spatial planning in urban and rural settlements.

Keywords: land use management, rural settlement, spatial development framework, spatial planning

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Authors: Saleh Abdullah Dabil

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The research aims to survey the dates factories in Al-Kharj Province, and then identify the nature of a series of different production processes and the using of raw materials, as well as their finished products, and the extent of their impact on the environment or consumers satisfaction. Twenty dates factories were selected according to their willingness to participate. The participants of dates factories consist of approximately 40 % of all dates factories in Al-Kharj province. All of the dates factories which were visited were observed. The research team also administered number of questionnaires to the public to know their satisfaction levels of the dates products as well as their suggestions. It is accounted to 237 participants who gave their opinion about the dates products and their suggestions. This study is one of rare studies about green marketing in dates factories. What is new about this study is that it depends upon both of the managers and consumers as well as the researchers to look into the factories’ production line and to observe the level of satisfaction. The study resulted in a very good ending because that the green marketing of dates is in its highest level. This indicates that the factories in general using natural materials and no bad materials or subsides used in the production, the levels of satisfaction by consumers are very good, preferring mostly lose product of dates. The preference of lose dates means the tendency to use the dates in their natural product. The recommendations of this study suggest solving marketing problems in transforming raw dates into manufacturing products. This includes biscuits and other types of sweet products.

Keywords: green marketing, dates factories, environment impact, consumer satisfaction

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Authors: A. Amiri Delouei

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In the current study, two-dimensional unsteady heat conduction in a functionally graded cylinder is studied analytically. The temperature distribution is in radial and longitudinal directions. Heat conduction coefficients are considered a power function of radius both in radial and longitudinal directions. The proposed solution can exactly satisfy the boundary conditions. Analytical unsteady temperature distribution for different parameters of functionally graded cylinder is investigated. The achieved exact solution is useful for thermal stress analysis of functionally graded cylinders. Regarding the analytical approach, this solution can be used to understand the concepts of heat conduction in functionally graded materials.

Keywords: functionally graded materials, unsteady heat conduction, cylinder, temperature distribution

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Authors: Jin-Hong Kim

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Hydraulic analysis on microhabitat of Benthic Macro- invertebrates was performed at riparian riffles of Hongcheon River and Gapyeong Stream. As for the representative species, Ecdyonurus kibunensis, Paraleptophlebia cocorata, Chironomidae sp. and Psilotreta kisoensis iwata were chosen. They showed hydraulically different habitat types by flow velocity and particle diameters of streambed materials. Habitat conditions of the swimmers were determined mainly by the flow velocity rather than by flow depth or by riverbed materials. Burrowers prefer sand and silt, and inhabited at the riverbed. Sprawlers prefer cobble or boulder and inhabited for velocity of 0.05-0.15 m/s. Clingers prefer pebble or cobble and inhabited for velocity of 0.06-0.15 m/s. They were found to be determined mainly by the flow velocity.

Keywords: benthic macroinvertebrates, riffles, clinger, swimmer, burrower, sprawler

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Authors: Rui Tu, Yakui Bai, Huailin Li

Abstract:

The lead-bismuth eutectic (LBE) alloy is a promising candidate of coolant in the fast neutron reactors and accelerator-driven systems (ADS) because of its good properties, such as low melting point, high neutron yields and high thermal conductivity. Although the corrosion of the structure materials caused by the liquid metal (LM) coolant is a challenge to the safe operating of a lead-bismuth eutectic nuclear reactor. Thermodynamic theories, experiential formulas and experimental data can be used for explaining the maintenance of the protective oxide layers on stainless steels under satisfaction oxygen concentration, but the atomic scale insights of such anti-corrosion mechanisms are little known. In the present work, the first-principles calculations are carried out to study the effects of oxygen partial pressure on the formation energies of the liquid metal coolant relevant impurity defects in the anti-corrosion oxide films on the surfaces of the structure materials. These approaches reveal the microscope mechanisms of the corrosion of the structure materials, especially for the influences from the oxygen partial pressure. The results are helpful for identifying a crucial oxygen concentration for corrosion control, which can ensure the systems to be operated safely under certain temperatures.

Keywords: oxygen partial pressure, liquid metal coolant, TDDFT, anti-corrosion layer, formation energy

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Authors: Amgad Rezk, Heba Ahmed, Leslie Yeo

Abstract:

Ultrasound presents a powerful means for material synthesis. In this talk, we showcase a new field demonstrating the possibility for harnessing sound energy sources at considerably higher frequencies (10 MHz to 1 GHz) compared to conventional ultrasound (kHz and up to ~2 MHz) for crystalising and manipulating a variety of nanoscale materials. At these frequencies, cavitation—which underpins most sonochemical processes—is largely absent, suggesting that altogether fundamentally different mechanisms are at dominant. Examples include the crystallization of highly oriented structures, quasi-2D metal-organic frameworks and nanocomposites. These fascinating examples reveal how the highly nonlinear electromechanical coupling associated with high-frequency surface vibration gives rise to molecular ordering and assembly on the nano and microscale.

Keywords: high-frequency acoustics, microfluidics, crystallisation, composite nanomaterials

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Authors: Pradeep Raj Sharma, Bogeun Jang, Jongill Hong

Abstract:

Spin-orbit torque (SOT) is an efficient approach for manipulating the magnetization of ferromagnetic materials (FMs), providing improved device performance, better compatibility, and ultra-fast switching with lower power consumption compared to spin-transfer torque (STT). Among the various materials and structural designs, two-dimensional (2D) van-der Waals (vdW) layered materials and their heterostructures have been demonstrated as highly scalable and promising device architecture for SOT. In particular, a bilayer heterostructure consisting of fully 2D-vdW-FM, non-magnetic material (NM) offers a potential platform for controlling the magnetization using SOT because of the advantages of being easy to scale and less energy to switch. Here, we report filed-free deterministic switching driven by SOT at room temperature, integrating perpendicularly magnetized 2D-vdW material Fe₃GaTe₂ (FGaT) and NM WTe₂. Pulse current-induced magnetization switching with an ultra-low current density of about 6.5×10⁵ A/cm², yielding a SOT efficiency close to double-digits at 300 K, is reported. These values are two orders of magnitude higher than those observed in conventional heavy metal (HM) based SOT and exceed those reported with 2D-vdW layered materials. WTe₂, a topological semimetal possessing strong SOC and high spin Hall angle, can induce significant spin accumulation with negligible spin loss across the transparent 2D bilayer heterointerface. This promising device architecture enables highly compatible, energy-efficient, non-volatile memory and lays the foundation for designing efficient, flexible, and miniaturized spintronic devices.

Keywords: spintronics, spin-orbit torque, spin Hall effect, spin Hall angle, topological semimetal, perpendicular magnetic anisotropy

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Authors: H. Yanar, G. Purcek, H. H. Ayar

Abstract:

The ingredients of composite materials used for the production of composite brake pads play an important role in terms of safety braking performance of automobiles and trains. Therefore, the ingredients must be selected carefully and used in appropriate ratios in the matrix structure of the brake pad materials. In the present study, a non-asbestos organic composite brake pad materials containing binder resin, space fillers, solid lubricants, and friction modifier was developed, and its fillers content was optimized by adding natural rubber with different rate into the specified matrix structure in order to achieve the best combination of tribo-performance and mechanical properties. For this purpose, four compositions with different rubber content (2.5wt.%, 5.0wt.%, 7.5wt.% and 10wt.%) were prepared and then test samples with the diameter of 20 mm and length of 15 mm were produced to evaluate the friction and mechanical behaviors of the mixture. The friction and wear tests were performed using a pin-on-disc type test rig which was designed according to NF-F-11-292 French standard. All test samples were subjected to two different types of friction tests defined as periodic braking and continuous braking (also known as fade test). In this way, the coefficient of friction (CoF) of composite sample with different rubber content were determined as a function of number of braking cycle and temperature of the disc surface. The results demonstrated that addition of rubber into the matrix structure of the composite caused a significant change in the CoF. Average CoF of the composite samples increased linearly with increasing rubber content into the matrix. While the average CoF was 0.19 for the rubber-free composite, the composite sample containing 20wt.% rubber had the maximum CoF of about 0.24. Although the CoF of composite sample increased, the amount of specific wear rate decreased with increasing rubber content into the matrix. On the other hand, it was observed that the CoF decreased with increasing temperature generated in-between sample and disk depending on the increasing rubber content. While the CoF decreased to the minimum value of 0.15 at 400 °C for the rubber-free composite sample, the sample having the maximum rubber content of 10wt.% exhibited the lowest one of 0.09 at the same temperature. Addition of rubber into the matrix structure decreased the hardness and strength of the samples. It was concluded from the results that the composite matrix with 5 wt.% rubber had the best composition regarding the performance parameters such as required frictional and mechanical behavior. This composition has the average CoF of 0.21, specific wear rate of 0.024 cm³/MJ and hardness value of 63 HRX.

Keywords: brake pad composite, friction and wear, rubber, friction materials

Procedia PDF Downloads 137

Authors: Eva Stefanovska, Estefania Cuenca, Aleksandra Momirov, Monika Fidanchevska, Liberato Ferrara, Emilija Fidanchevski

Abstract:

Silica is used in construction materials as a part of natural raw materials or as an additive in powder form (micro and nano dimensions). SiO₂ particles in cement act as centers of nucleation, as a filler or as pozzolan material. In this regard, silica improves the microstructure of cementitious composites, increases the mechanical properties, and finally also results into improved durability of the final products. Improved properties of cementitious composites may lead to better structural efficiency, which, together with increased durability, results into increased sustainability signature of structures made with this kind of materials. The aim of the present work was to investigate the influence of silica on the properties of cement. Fly ash (as received and mechanically activated) and synthetized silica (sol-gel method using TEOS as precursor) was used in the investigation as source of silica. Four types of cement mixtures were investigated (reference cement paste, cement paste with addition of 15wt.% as-received fly ash, cement paste with 15 wt.% mechanically activated fly ash and cement paste with 14wt.% mechanically activated fly ash and 1 wt.% silica). The influence of silica on setting time and mechanical properties (2, 7 and 28 days) was followed. As a matter of fact it will be shown that cement paste with composition 85 wt. % cement, 14 wt.% mechanically activated fly ash and 1 wt. % SiO₂ obtained by the sol-gel method was the best performing one, with increased compressive and flexure strength by 9 and 10 % respectively, as compared to the reference mixture. Acknowledgements: 'COST Action CA15202, www.sarcos.eng.cam.ac.uk'

Keywords: cement, fly ash, mechanical properties, silica, sol-gel

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Authors: Roham Rafiee, Behzad Mazhari

Abstract:

Composite structures, having incredible properties, have gained considerable popularity in the last few decades. Among all types, polymer matrix composites are being used extensively due to their unique characteristics including low weight, convenient fabrication process and low cost. Having polymer as matrix, these type of composites show different creep behavior when compared to metals and even other types of composites since most polymers undergo creep even in room temperature. One of the most challenging topics in creep is to introduce new techniques for predicting long term creep behavior of materials. Depending on the material which is being studied the appropriate method would be different. Methods already proposed for predicting long term creep behavior of polymer matrix composites can be divided into five categories: (1) Analytical Modeling, (2) Empirical Modeling, (3) Superposition Based Modeling (Semi-empirical), (4) Rheological Modeling, (5) Finite Element Modeling. Each of these methods has individual characteristics. Studies have shown that none of the mentioned methods can predict long term creep behavior of all PMC composites in all circumstances (loading, temperature, etc.) but each of them has its own priority in different situations. The reason to this issue can be found in theoretical basis of these methods. In this study after a brief review over the background theory of each method, they are compared in terms of their applicability in predicting long-term behavior of composite structures. Finally, the explained materials are observed through some experimental studies executed by other researchers.

Keywords: creep, comparative study, modeling, composite materials

Procedia PDF Downloads 441