Search results for: mechanical and tribological behaviour

Authors: C. A. Bradley, D. Patsios, D. Berridge

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This paper presents evidence to better understand the risk and protective factors related to sibling conflict and the patterns of association between sibling conflict and negative adjustment outcomes by incorporating additional familial and societal factors within statistical models of risk and adjustment. It was conducted through the secondary analysis of a large representative cross-sectional dataset of children in the UK. The original study includes proxy interviews for young children and self-report interviews for adolescents. The study applies an ecological systems framework for the analyses. Hierarchical regression models assess risk and protective factors and adjustment outcomes associated with sibling conflict. Interactions reveal differential effect between contextual risk factors and the social context of influence. The general pattern of findings suggested that, although factors affecting likelihood of experiencing sibling conflict were often determined by child age, some remained consistent across childhood. These factors were often conditional on each other, reinforcing the importance of an ecological framework. Across both age-groups, sibling conflict was associated with siblings closer in age; male sibling groups; most advantaged socio-economic group; and exposure to community violence, such as witnessing violent assault or robbery. The study develops the evidence base on the influence of ethnicity and socio-economic group on sibling conflict by exploring interactions between social context. It also identifies key new areas of influence – such as family structure, disability, and community violence in exacerbating or reducing risk of conflict. The study found negative associations between sibling conflict and young children’s mental well-being and adolescents' mental well-being and anti-social behaviour, but also more context specific associations – such as sibling conflict moderating the negative impact of adversity and high risk experiences for young children such as parental violence toward the child.

Keywords: adjustment, conflict, ecological systems, family systems, risk and protective factors, sibling

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Authors: Flavio Araujo, Paulo Scalize, Julio Lima, Natalia Vieira, Antonio Albuquerque, Isabela Santos

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From a concern regarding the environmental impacts caused by the disposal of residues generated in Water Treatment Plants (WTP's), alternatives ways have been studied to use these residues as raw material for manufacture of building materials, avoiding their discharge on water streams, disposal on sanitary landfills or incineration. This paper aims to present the results of a research work, which is using WTR for replacing the soil content in the manufacturing of soil-cement floor with proportions of 0, 5, 10 and 15%. The samples tests showed a reduction mechanical strength in so far as has increased the amount of waste. The water absorption was below the maximum of 6% required by the standard. The application of WTR contributes to the reduction of the environmental damage in the water treatment industry.

Keywords: residue, soil-cement floor, sustainable, WTP

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Authors: Andrei Shishkin, Aleksandrs Korjakins, Viktors Mironovs

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Present paper describes method of obtaining clay ceramic foam (CCF) and foam concrete (FC), by direct foaming with high speed mixer-disperser (HSMD). Three foaming agents (FA) are compared for the FC and CCF production: SCHÄUMUNGSMITTEL W 53 FLÜSSIG (Zschimmer & Schwarz Gmbh, Germany), SCF-1245 (Sika, test sample, Latvia) and FAB-12 (Elade, Latvija). CCF were obtained at 950, 1000°C, 1150°C and 1150°C firing temperature and have mechanical compressive strength 1.2, 2.55, and 4.3 MPa and porosity 79.4, 75.1, 71.6%, respectively. Obtained FC has 6-14 MPa compressive strength and porosity 44-55%. The goal of this work was the development of a sustainable and durable ceramic cellular structures using HSMD.

Keywords: ceramic foam, foam concrete, clay foam, open cell, close cell, direct foaming

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Authors: Adewale O. Adegbenjo, Elsie Nsiah-Baafi, Mxolisi B. Shongwe, Mercy Ramakokovhu, Peter A. Olubambi

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The sintering step in powder metallurgy (P/M) processes is very sensitive as it determines to a large extent the properties of the final component produced. Spark plasma sintering over the past decade has been extensively used in consolidating a wide range of materials including metallic alloy powders. This novel, non-conventional sintering method has proven to be advantageous offering full densification of materials, high heating rates, low sintering temperatures, and short sintering cycles over conventional sintering methods. Ti6Al4V has been adjudged the most widely used α+β alloy due to its impressive mechanical performance in service environments, especially in the aerospace and automobile industries being a light metal alloy with the capacity for fuel efficiency needed in these industries. The P/M route has been a promising method for the fabrication of parts made from Ti6Al4V alloy due to its cost and material loss reductions and the ability to produce near net and intricate shapes. However, the use of this alloy has been largely limited owing to its relatively poor hardness and wear properties. The effect of sintering temperature on the densification, hardness, and wear behaviors of spark plasma sintered Ti6Al4V powders was investigated in this present study. Sintering of the alloy powders was performed in the 650–850°C temperature range at a constant heating rate, applied pressure and holding time of 100°C/min, 50 MPa and 5 min, respectively. Density measurements were carried out according to Archimedes’ principle and microhardness tests were performed on sectioned as-polished surfaces at a load of 100gf and dwell time of 15 s. Dry sliding wear tests were performed at varied sliding loads of 5, 15, 25 and 35 N using the ball-on-disc tribometer configuration with WC as the counterface material. Microstructural characterization of the sintered samples and wear tracks were carried out using SEM and EDX techniques. The density and hardness characteristics of sintered samples increased with increasing sintering temperature. Near full densification (99.6% of the theoretical density) and Vickers’ micro-indentation hardness of 360 HV were attained at 850°C. The coefficient of friction (COF) and wear depth improved significantly with increased sintering temperature under all the loading conditions examined, except at 25 N indicating better mechanical properties at high sintering temperatures. Worn surface analyses showed the wear mechanism was a synergy of adhesive and abrasive wears, although the former was prevalent.

Keywords: hardness, powder metallurgy, spark plasma sintering, wear

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Authors: Yohanes Chekol Malede

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σ-phase has negative effects on the corrosion responses and the mechanical properties of steels. The growth of σ-phase in the austenite matrix of AISI 347H FG steel was simulated using DICTRA software using CALPHAD method. The simulation work included the influence of both volume diffusion and grain boundary diffusion. The simulation results showed a good agreement with the experimental findings. The simulation results revealed a Cr-depleted and a Ni-enriched σ-phase/austenite interface. Effects of temperature, grain size, and composition of alloying elements on the growth kinetics of σ-phase were assessed. The simulated results were fitted to the JMAK equation and a good correlation was obtained.

Keywords: AISI 347H FG austenitic steel, CALPHAD, sigma phase, microstructure evolution

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Authors: I. Benkaddour, Y. Benkaddour, A. Benk Addour

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The structural, elastic, Thermal, electronic, and magnetic properties of intermetallic RMn₂Ge₂ (R= Ca, Y, Nd) are investigated by density functional theory (DFT), using the full potential –linearised augmented plane wave method (FP-LAPW). In this approach, the local-density approximation (LDA) is used for the exchange-correlation (XC) potential. The equilibrium lattice constant and magnetic moment agree well with the experiment. The density of states shows that these phases are conductors, with contribution predominantly from the R and Mn d states. We have determined the elastic constants C₁₁, C₁₂, C₁₃, C₄₄, C₃₃, andC₆₆ at ambient conditions in, which have not been established neither experimentally nor theoretically. Thermal properties, including the relative expansion coefficients and the heat capacity, have been estimated using a quasi-harmonic Debye model.

Keywords: RMn₂Ge₂, intermetallic, first-principles, density of states, mechanical properties

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Authors: Simone Tedeschi, Francesco Crespi, Paolo Liberati, Massimo Paradiso, Antonio Sciala

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This paper aims at contributing to the understanding of smokers’ responses to cigarette prices increases with a focus on heterogeneity, both across individuals and price levels. To do this, a stated preference quasi-experimental design grounded in a random utility framework is proposed to evaluate the effect on smokers’ utility of the price level and variation, along with social conditioning and health impact perception. The analysis is based on individual-level data drawn from a unique survey gathering very detailed information on Italian smokers’ habits. In particular, qualitative information on the individual reactions triggered by changes in prices of different magnitude and composition are exploited. The main findings stemming from the analysis are the following; the average price elasticity of cigarette consumption is comparable with previous estimates for advanced economies (-.32). However, the decomposition of this result across five latent-classes of smokers, reveals extreme heterogeneity in terms of price responsiveness, implying a potential price elasticity that ranges between 0.05 to almost 1. Such heterogeneity is in part explained by observable characteristics such as age, income, gender, education as well as (current and lagged) smoking intensity. Moreover, price responsiveness is far from being independent from the size of the prospected price increase. Finally, by comparing even and uneven price variations, it is shown that uniform across-brand price increases are able to limit the scope of product substitutions and downgrade. Estimated price-response heterogeneity has significant implications for tax policy. Among them, first, it provides evidence and a rationale for why the aggregate price elasticity is likely to follow a strictly increasing pattern as a function of the experienced price variation. This information is crucial for forecasting the effect of a given tax-driven price change on tax revenue. Second, it provides some guidance on how to design excise tax reforms to balance public health and revenue goals.

Keywords: smoking behaviour, preference heterogeneity, price responsiveness, cigarette taxation, random utility models

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Authors: Deepa Shokeen, Bani Tamber Aeri

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Food environments are believed to play a significant role in the obesity epidemic and robust research methods are required to establish which factors or aspects of the food environment are relevant to food choice and to adiposity. The relationship between the food environment and obesity is complex. While there is little research linking food access with obesity as an outcome measure in any age group, with the help of this article we will try to understand the relationship between what we eat and the environmental context in which these food choices are made. Methods: A literature search of studies published between January 2000 and December 2013 was undertaken on computerized medical, social science, health, nutrition and education databases including Google, PubMed etc. Reports of organisations such as World Health Organisation (WHO), Centre for Chronic Disease Control (CCDC) were studied to project the data. Results: Studies show that food environments play a significant role in the obesity epidemic and robust research methods are required to establish which factors or aspects of the food environment are relevant to food choice and to adiposity. Evidence indicates that the food environment may help explain the obesity and cardio-metabolic risk factors among young adults. Conclusion: Cardiovascular disease is the ever growing chronic disease, the incidence of which will increase markedly in the coming decades. Therefore, it is the need of the hour to assess the prevalence of various risk factors that contribute to the incidence of cardiovascular diseases especially in the work environment. Research is required to establish how different environments affect different individuals as individuals interact with the environment on a number of levels. We need to ascertain the impact of selected food and nutrition environments (Information, organization, community, consumer) on food choice and dietary intake of the working adults as it is important to learn how these food environments influence the eating perceptions and health behaviour of the adults.

Keywords: food environment, prevalence, cardiovascular disease, India, worksite, risk factors

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Authors: Wu Xiaoguang, Liu Jiaxin, Fang Miaomiao, Wei Saidong

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There are many prestressed concrete prefabricated girder Bridges with small and medium span and the damage is serious. This paper mainly study the effect of prestress loss of prefabricated bridge bearing performance, through the establishment of ANSYS finite element model, from the condition of different prestress loss research, get the stress and strain data, draw curve, finally get the following conclusion: loss of prestress can reduce the ultimate bearing capacity of Bridges, the side span across the deflection value than the influence of times side span, the influence of the deflection in the midspan cross value. Therefore, the prestress loss and the effective prestress should be strictly considered in the design and construction process.

Keywords: across the deflection, loss of prestress, prefabricated girder bridge, the main tensile stress

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Authors: Marcel Schneider, Nils Nießen

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Microscopic simulation programs enable the description of the two processes of railway operation and the previous timetabling. Occupation conflicts are often solved based on defined train priorities on both process levels. These conflict resolutions produce knock-on delays for the involved trains. The sum of knock-on delays is commonly used to evaluate the quality of railway operations. It is either compared to an acceptable level-of-service or the delays are evaluated economically by linearly monetary functions. It is impossible to properly evaluate dispatching decisions without a well-founded objective function. This paper presents a new approach for evaluation of dispatching decisions. It uses models of choice of transport and considers the behaviour of the end-costumers. These models evaluate the knock-on delays in more detail than linearly monetary functions and consider other competing modes of transport. The new approach pursues the coupling of a microscopic model of railway operation with the macroscopic model of choice of transport. First it will be implemented for the railway operations process, but it can also be used for timetabling. The evaluation considers the possibility to change over to other transport modes by the end-costumers. The new approach first looks at the rail-mounted and road transport, but it can also be extended to air transport. The split of the end-costumers is described by the modal-split. The reactions by the end-costumers have an effect on the revenues of the railway undertakings. Various travel purposes has different pavement reserves and tolerances towards delays. Longer journey times affect besides revenue changes also additional costs. The costs depend either on time or track and arise from circulation of workers and vehicles. Only the variable values are summarised in the contribution margin, which is the base for the monetary evaluation of the delays. The contribution margin is calculated for different resolution decisions of the same conflict. The conflict resolution is improved until the monetary loss becomes minimised. The iterative process therefore determines an optimum conflict resolution by observing the change of the contribution margin. Furthermore, a monetary value of each dispatching decision can also be determined.

Keywords: choice of transport, knock-on delays, monetary evaluation, railway operations

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Authors: Sangeeta Girdhar, Amanat Grewal, Nahush Bansal

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Introduction: There is an increasing burden of hypertension in India. The morbidity and mortality arising from complications are mainly due to non-adherence to medication, unhealthy dietary habits, and lack of physical activity. Non-adherence is a well-recognised factor contributing to inadequate control of high blood pressure. Adherence to pharmacotherapy for hypertension varies from 43% to 88%. Non-adherence is influenced by various socio-demographic factors. Understanding these factors is useful in managing non-adherence. Therefore, the study was planned to determine adherence among hypertensives and factors associated with non-adherence to treatment. Methodology: A cross-sectional study was conducted at Urban Health Training Centre of Dayanand Medical College and Hospital Ludhiana. Patients attending the OPD over a period of 3 months were included in the study. Prior ethical approval was obtained, and informed consent was taken from subjects. A predesigned semi-structured questionnaire was applied, which included socio-demographic profile, treatment-seeking behaviour, adherence to the antihypertensive medication, lifestyle factors (intake of alcohol, smoking, consumption of junk food, high salt intake) contributing to the development of the disease. Reasons for non-adherence to the therapy were also explored. Data was entered into excel, and SPSS 26 version was used for analysis. Results: A total of 186 individuals were interviewed. Out of these, 113 females (60.8%) and 73 males (39.2%) participated in the study. Mean age of participants was 60.9 ± 10.7 years. Adherence to anti-hypertensive treatment was found in 68.3% of the participants. It was observed that adherence was more in literate individuals as compared to illiterate (p value- 0.78). Adherence was lower among smokers (33.3%) and alcohol consumers (53.8%) as compared to non-users (69.4% and 70.6%, respectively). The predominant reasons for skipping medications were discontinuing medication when feeling well, forgetfulness and unawareness. Conclusion: There is a need to generate awareness regarding the importance of adherence to therapy among patients. Intensive health education and counselling of the patients is the need of the hour.

Keywords: hypertension, anti-hypertensive, adherence, counselling

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Authors: G. Hemath Kumar, H. Mohit, K. Karthick

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One of the most important issues in the composite technology is the repairing of parts of aircraft structures which is manufactured from composite materials. In such applications and also for joining various composite parts together, they are fastened together either using adhesives or mechanical fasteners. The tensile strength of these joints was carried out using Universal Testing Machine (UTM). A parametric study was also conducted to compare the performance of the hybrid joint with varying adherent thickness, adhesive thickness and overlap length. The composition of the material is combination of epoxy resin and carbon fibre under the method of reinforcement. To utilize the full potential of composite materials as structural elements, the strength and stress distribution of these joints must be understood. The study of tensile strength in the members involved under various design conditions and various joints were took place.

Keywords: carbon fiber, FRP composite, MMC, automotive

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Authors: Sumohon Matilal, Neveen Abdelrehim

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The purpose of this study is to examine the way households manage the risks of civil war, using the calculative practices of accounting as a lens. As is the case with other social phenomena, accounting serves as a conduit for attributing values and rationales to crisis and in the process makes it visible and calculable. Our focus, in particular, is on the dialogue facilitated by the numerical logic of accounting between the householder and a crisis scenario, such as civil war. In other words, we seek to study how the risk of war is rationalized through household budgets, income and expenditure statements etc. and how such accounting constructs in turn shape attitudes toward earnings and spending in a wartime economy. The existing literature on war and accounting demonstrates how an accounting logic can have potentially destabilising consequences and how it is used to legitimise war. However, very few scholars have looked at the way accounting constructs are used to internalise the effects of war in an average household and the behavioural consequences that arise from such accounting. Relatedly, scholars studying household accounting have mostly focussed on the links between gender and hierarchy in relation to managing the financial affairs. Few have focused on the role of household accounts in a crisis scenario. This study intends to fill this gap. We draw upon Egypt, a country in the middle of civil war since 2011 for our purpose. We intend to carry out 15-20 semi-structured interviews with middle income households in Cairo that maintain some form of accounts to study the following issues: 1. How do people internalise the risks of civil war? What kind of accounting constructs do they use (this may take the form of simple budgets, income-expenditure notes/statements on a periodic basis, spreadsheets etc.) 2. How has civil war affected household expenditure? Are people spending more/less than before? 3. How has civil war affected household income? Are people finding it difficult/easy to survive on the pre-war income? 4. How is such accounting affecting household behaviour towards earnings and expenditure? Are families prioritising expenditure on necessities alone? Are they refraining from indulging in luxuries? Are family members doing two or three jobs to cope with difficult times? Are families increasingly turning toward borrowing? Is credit available? From whom?

Keywords: risk, accounting, war, crisis

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Authors: N. Tugrul, E. Sariburun, F. T. Senberber, A. S. Kipcak, E. Moroydor Derun, S. Piskin

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Boron-gypsum is a waste which occurs in the boric acid production process. In this study, the boron content of this waste is evaluated for the use in synthesis of magnesium borates and such evaluation of this kind of waste is useful more than storage or disposal. Magnesium borates, which are a sub-class of boron minerals, are useful additive materials for the industries due to their remarkable thermal and mechanical properties. Magnesium borates were obtained hydrothermally at different temperatures. Novelty of this study is the search of the solution density effects to magnesium borate synthesis process for the increasing the possibility of boron-gypsum usage as a raw material. After the synthesis process, products are subjected to XRD and FT-IR to identify and characterize their crystal structure, respectively.

Keywords: boron-gypsum, hydrothermal synthesis, magnesium borate, solution density

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Authors: Alò Roberta, Bottiglione Francesco, Mantriota Giacomo

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The efficiency of the actuation system of lower limb exoskeletons and of active orthoses is a significant aspect of the design of such devices because it affects their efficacy. F-IVT is an innovative actuation system to power artificial knee joint with energy recovery capabilities. Its key and non-conventional elements are a flywheel, that acts as a mechanical energy storage system, and an Infinitely Variable Transmission (IVT). The design of the F-IVT can be optimized for a certain walking condition, resulting in a heavy reduction of both the electric energy consumption and of the electric peak power. In this work, by means of simulations of level ground walking at different speeds, it is demonstrated how F-IVT is still an advantageous actuator, even when it does not work in nominal conditions.

Keywords: active orthoses, actuators, lower extremity exoskeletons, knee joint

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Authors: Marcus Walter, Norbert Nitzsche, Dirk Odenthal, Steffen Müller

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This contribution presents a friction estimator for industrial purposes which identifies Coulomb friction in a steering system. The estimator only needs a few, usually known, steering system parameters. Friction occurs on almost every mechanical system and has a negative influence on high-precision position control. This is demonstrated on a steering angle controller for highly automated driving. In this steering system the friction induces limit cycles which cause oscillating vehicle movement when the vehicle follows a given reference trajectory. When compensating the friction with the introduced estimator, limit cycles can be suppressed. This is demonstrated by measurements in a series vehicle.

Keywords: friction estimation, friction compensation, steering system, lateral vehicle guidance

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Authors: Christina Zourna, Ioanna Papavassiliou-Alexiou

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Drama in Education (DiE) is a dynamic experiential method that can be used in many interdisciplinary contexts. In the Educational and Social Policy Department, University of Macedonia, Thessaloniki, Greece, DiE is being used as a core method for developing professional competences in pre- and postgraduate courses as well as adult education training programs. In this presentation, an innovative DiE application will be described concerning the development of educational leaders’ skills necessary to meet unprecedented, unexpected challenges in the 21st century schools. In a non-threatening risk-taking no-penalty environment, future educational leaders live-in-role problems, challenges, and dilemmas before having to face similar ones in their profession. Through personal involvement, emotional engagement, and reflection, via individual and group activities, they experience the behaviour, dilemmas, decision-making processes, and informed choices of a recognized leader and are able to make connections with their own life. As pretext serves the life of Alexander the Great, the Macedonian King who defeated the vast Persian empire in the 4th century BC and, by uniting all Greeks, conquered the up-to-date known eastern world thanks to his authentic leadership skills and exceptional personality traits. Since the early years of his education mastered by the famous Greek philosopher Aristotle, Alexander proved his unique qualities by providing the world with the example of an undeniably genuine, inspirational, effective, and most recognizable authentic leader. Through questionnaires and individual interviews, participants in these workshops revealed how they developed active listening, empathy, creativity, imagination, critical strategic and out-of-the-box thinking, cooperation and own vision communicating, crisis management skills, self-efficacy, self-awareness, self-exposure, information management, negotiation and inspiration skills, enhanced sense of responsibility and commitment, and decision-making skills.

Keywords: drama in education method, educational leadership, professional competences, skills’ development

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Authors: Anuruddha Jayasuriya, Thanakorn Pheeraphan

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In this paper, a review of different mathematical models which can be used as prediction tools to assess the time to crack reinforced concrete (RC) due to corrosion is investigated. This investigation leads to an experimental study to validate a selected prediction model. Most of these mathematical models depend upon the mechanical behaviors, chemical behaviors, electrochemical behaviors or geometric aspects of the RC members during a corrosion process. The experimental program is designed to verify the accuracy of a well-selected mathematical model from a rigorous literature study. Fundamentally, the experimental program exemplifies both one-dimensional chloride diffusion using RC squared slab elements of 500 mm by 500 mm and two-dimensional chloride diffusion using RC squared column elements of 225 mm by 225 mm by 500 mm. Each set consists of three water-to-cement ratios (w/c); 0.4, 0.5, 0.6 and two cover depths; 25 mm and 50 mm. 12 mm bars are used for column elements and 16 mm bars are used for slab elements. All the samples are subjected to accelerated chloride corrosion in a chloride bath of 5% (w/w) sodium chloride (NaCl) solution. Based on a pre-screening of different models, it is clear that the well-selected mathematical model had included mechanical properties, chemical and electrochemical properties, nature of corrosion whether it is accelerated or natural, and the amount of porous area that rust products can accommodate before exerting expansive pressure on the surrounding concrete. The experimental results have shown that the selected model for both one-dimensional and two-dimensional chloride diffusion had ±20% and ±10% respective accuracies compared to the experimental output. The half-cell potential readings are also used to see the corrosion probability, and experimental results have shown that the mass loss is proportional to the negative half-cell potential readings that are obtained. Additionally, a statistical analysis is carried out in order to determine the most influential factor that affects the time to corrode the reinforcement in the concrete due to chloride diffusion. The factors considered for this analysis are w/c, bar diameter, and cover depth. The analysis is accomplished by using Minitab statistical software, and it showed that cover depth is the significant effect on the time to crack the concrete from chloride induced corrosion than other factors considered. Thus, the time predictions can be illustrated through the selected mathematical model as it covers a wide range of factors affecting the corrosion process, and it can be used to predetermine the durability concern of RC structures that are vulnerable to chloride exposure. And eventually, it is further concluded that cover thickness plays a vital role in durability in terms of chloride diffusion.

Keywords: accelerated corrosion, chloride diffusion, corrosion cracks, passivation layer, reinforcement corrosion

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Authors: Juraj Beniak, Ľubomír Šooš, Peter Križan, Miloš Matúš

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Within Rapid Prototyping technologies are used many types of materials. Many of them are recyclable but there are still as plastic like, so practically they do not degrade in the landfill. Polylactic acid (PLA) is one of the special plastic materials which are biodegradable and also available for 3D printing within Fused Deposition Modelling (FDM) technology. The question is, if the mechanical properties of produced models are comparable to similar technical plastic materials which are usual for prototype production. Presented paper shows the experiments results for tensile strength measurements for specimens prepared with different 3D printer settings and model orientation. Paper contains also the comparison of tensile strength values with values measured on specimens produced by conventional technologies as injection moulding.

Keywords: 3D printing, biodegradable plastic, fused deposition modeling, PLA plastic, rapid prototyping

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Authors: Saloni Pandya, Nikhil Sharma, Ajanta Sachan

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Expansive soils in the unsaturated state are part of vadose zone and encountered in several arid and semi-arid parts of the world. Influence of high temperature, low precipitation and alternate cycles of wetting and drying are responsible for the chemical weathering of rocks, which results in the formation of expansive soils. Shrinkage-swelling (expansive) soils cover a substantial portion of area in India. Damages caused by expansive soils to various geotechnical structures are alarming. Matric suction develops in unsaturated soil due to capillarity and surface tension phenomena. Matric suction influences the geometric arrangement of soil skeleton, which induces the volume change behaviour of expansive soil. In the present study, an attempt has been made to evaluate the role of matric suction in the mechanism behind swelling characteristics of expansive soil. Four different soils have been collected from different parts of India for the current research. Soil sample S1, S2, S3 and S4 were collected from Nagpur, Bharuch, Bharuch-Dahej highway and Ahmedabad respectively. DFSI (Differential Free Swell Index) of these soils samples; S1, S2, S3, and S4; were determined to be 134%, 104%, 70% and 30% respectively. X-ray diffraction analysis of samples exhibited that percentage of Montmorillonite mineral present in the soils reduced with the decrease in DFSI. A series of constant volume swell pressure tests and in-contact filter paper tests were performed to evaluate swelling pressure and matric suction of all four soils at 30% saturation and 1.46 g/cc dry density. Results indicated that soils possessing higher DFSI exhibited higher matric suction as compared to lower DFSI expansive soils. Significant influence of matric suction on swelling pressure of expansive soils was observed with varying DFSI values. Higher matric suction of soil might govern the water uptake in the interlayer spaces of Montmorillonite mineral present in expansive soil leading to crystalline swelling.

Keywords: differential free swell index, expansive soils, matric suction, swelling pressure

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Authors: Nancy N. Sharmila, Aparna Mishra

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Hemiparesis affects almost 80% of stroke patients each year. It is marked by paralysis or weakness on one half of the body. Our model provides both assistance and physical therapy for hemiparesis patients for swift recovery. In order to accomplish our goal a force is provided that pulls the forearm up (as in flexing the arm), and pushes the forearm down (as in extending the arm), which will also assist the user during ADL (Activities of Daily Living). The model consists of a mechanical component which is placed around the patient’s bicep and an EMG control circuit to assist patients in daily activities, which makes it affordable and easy to use. In order to enhance the neuromuscular system’s effectiveness in synchronize the movement, proprioceptive neuromuscular facilitation (PNF) concept is used. The EMG signals are acquired from the unaffected arm as an input to drive the orthosis. This way the patient is invigorated to use the orthosis for regular exercise.

Keywords: EMG, hemiparesis, orthosis, rehabilitation

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Authors: Yusuf E. Mustapha, Inioluwa A Akindoyeni, Oluwatoyin G. Ezekiel, Ifeoluwa O. Awogbindin, Ebenezer O. Farombi

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Background: Parkinson's disease (PD) is the most prevalent motor disorder. Available therapies are palliative with no effect on disease progression. Kolaviron (KV), a natural anti-inflammatory and antioxidant agent, has been reported to possess neuroprotective effects in Parkinsonian flies and rats. Objective: The present study investigates the neuroprotective effect of KV, focusing on the DJ1/Nrf2 signaling pathway. Methodology: All-trans retinoic acid (ATRA, 10 mg/kg, i.p.) was used to inhibit Nrf2. Murine model of PD was established with four doses of MPTP (20 mg/kg i.p.) at 2 hours interval. MPTP mice were pre-treated with either KV (200 mg/kg/day p.o), ATRA, or both conditions for seven days before PD induction. Motor behaviour was evaluated, and markers of oxidative stress/damage and its regulators were assessed with immunofluorescence and ELISA techniques. Results: MPTP-treated mice covered less distance with reduced numbers of anticlockwise rotations, heightened freezing, and prolonged immobility when compared to control. However, KV significantly attenuated these deficits. Pretreatment of MPTP mice with KV upregulated Nrf2 expression beyond MPTP level with a remarkable reduction in Keap1 expression and marked elevation of DJ-1 level, whereas co-administration with ATRA abrogated these effects. KV treatment restored MPTP-mediated depletion of endogenous antioxidant, striatal oxidative stress, oxidative damage, and inhibition of acetylcholinesterase activity. However, ATRA treatment potentiated acetylcholinesterase inhibition and attenuated the protective effect of KV on the level of nitric oxide and activities of catalase and superoxide dismutase. Conclusion: Kolaviron protects Parkinsonian mice by stabilizing and activating the Nrf2 signaling pathway. Thus, kolaviron can be explored as a pharmacological lead in PD management.

Keywords: Garcinia kola, Kolaviron, Parkinson Disease, Nrf2, behavioral incompetence, neurodegeneration

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Authors: Djamel Djeghader, Bachir Redjel

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The composite materials of glass fibers can be used as a repair material for damage elements under repeated stresses, and in various environments. A cyclic bending characterization of a glass/polyester composite material was carried out with consideration of the period of immersion in water. These tests describe the behavior of materials and identify the mechanical fatigue characteristics using the Wohler Curve for different immersion time: 0, 90, 180 and 270 days in water. These curves are characterized by a dispersion in the lifetimes were modeled by straight whose intercepts are very similar and comparable to the static strength. This material deteriorates fatigue at a constant rate, which increases with increasing immersion time in water at a constant speed. The endurance limit seems to be independent of the immersion time in the water.

Keywords: fatigue, composite, glass, polyester, immersion, wohler

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Authors: E. Ramprasath, P. Manojkumar, P. Veena

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Proposed paper dealt with the modelling and analysis of induction motor based on the mathematical expression using the graphical programming environment of Laboratory Virtual Instrument Engineering Workbench (LabVIEW). Induction motor modelling with the mathematical expression enables the motor to be simulated with the various required parameters. Owing to the invention of variable speed drives study about the induction motor characteristics became complex.In this simulation motor internal parameter such as stator resistance and reactance, rotor resistance and reactance, phase voltage, frequency and losses will be given as input. By varying the speed of motor corresponding parameters can be obtained they are input power, output power, efficiency, torque induced, slip and current.

Keywords: induction motor, LabVIEW software, modelling and analysi, electrical and mechanical characteristics of motor

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Authors: Wojciech Grochala

Abstract:

AgF2 is an important two-dimensional antiferromagnet and an analogue of [CuO2]2– sheet. However, the strength of magnetic superexchange as well as magnetic dimensionality have not been explored before . Here we report our recent Raman and neutron scattering experiments which led to better understanding of the magnetic properties of the title compound. It turns out that intra-sheet magnetic superexchange constant reaches 70 meV, thus some 2/3 of the value measured for parent compounds of oxocuprate superconductors which is over 100 meV. The ratio of intra-to-inter-sheet superexchange constants is of the order of 102 rendering AgF2 a quasi-2D material, similar to the said oxocuprates. The quantum mechanical calculations reproduce the abovementioned values quite well and they point out to substantial covalence of the Ag–F bonding. After 3 decades of intense research on layered oxocuprates, AgF2 now stands as a second-to-none analogue of these fascinating systems. It remains to be seen whether this 012 parent compound may be doped in order to achieve superconductivity.

Keywords: antiferromagnets, superexchange, silver, fluorine

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Authors: Julia Wong, Hua Beng Lim, Petrina Goh, Johanna Foo, Caleb Ng, Nurul ‘Aqilah Bte Mohd Taufek

Abstract:

Animal-assisted therapy (AAT) utilizes human-animal interaction to achieve specific therapeutic goals, and its efficacy has been demonstrated across various settings overseas. The use of AAT in Singapore, however, is still limited. Ang Mo Kio-Thye Hua Kwan (AMKH) is one of the first community hospitals in Singapore to use AAT to complement its occupational therapy services with elderly patients. This study explored the perspectives of AMKH’s occupational therapists (OTs) in relation to AAT to understand barriers and enablers in implementing and practising AAT. We also examined how OTs at-large across practice settings perceive AAT. A mixed method design was used. 64 OTs at-large participated in on online survey, and 7 AMKH OTs were interviewed individually via Zoom. Survey results were analysed with descriptive and Mann-Whitney U tests. Interviews were thematically analysed. AMKH OTs perceived various benefits of AAT articulated in overseas studies in domains such as motivation and participation, emotional, social interaction, sensory tactile stimulation, and cognition. Interestingly, this perception was also supported by 67% of OTs who had responded to the survey, even though most of the OTs who had participated in the survey had no experience in AAT. Despite the perceived benefits of AAT, both OTs from AMKH and those at-large articulated concerns on risks pertaining to AAT (e.g., allergies, unexpected animal behaviour, infections, etc). However, AMKH OTs shared several ways to mitigate these risks, demonstrating their ability to develop a safe program. For e.g., volunteers and their dogs must meet specific recruitment criteria, stringent protocols are used to screen and match dogs with patients, and there are strict exclusion criteria for patients participating in AAT. AMKH OTs’ experience suggests that additional skills and knowledge are required to implement AAT, therefore, healthcare institutions should first consider improving their staff training and risk mitigation knowledge before implementing AAT. They can also refer to AMKH’s AAT protocols and those found in overseas studies, but institutions must adapt the protocols to fit their institutional settings and patients’ profiles.

Keywords: animal-assisted therapy, dog-assisted therapy, occupational therapy, complementary therapy

Procedia PDF Downloads 158

Authors: Alireza Rezagholilou

Abstract:

Moisture susceptibility of bituminous mixes directly affect the stripping of asphalt layers. The majority of relevant test methods are mechanical methods with low repeatability and consistency of results. Thus, this research aims to evaluate the physicochemical interactions of bitumen and aggregates based on the wettability concept. As such, the surface energies of components at the interface are measured by contact angle method. That gives an opportunity to investigate the adhesion properties of multiple mineral fillers at various percentages to explore the best dosage in the mix. Three types of fillers, such as hydrated lime, ground lime and rock powder, are incorporated into the bitumen mix for a series of sessile drop tests for both aggregates and binders. Results show the variation of adhesion properties versus filler (%).

Keywords: adhesion, contact angle, filler, surface energy, moisture susceptibility

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Authors: Andrew Kurochkin, Kostiantyn Bokhan

Abstract:

In this study, a new meme dataset of ~650K meme instances was created, a technology of meme generation based on the state of the art deep learning technique - GPT-2 model was researched, a comparative analysis of machine-generated memes and human-created was conducted. We justified that Amazon Mechanical Turk workers can be used for the approximate estimating of users' behavior in a social network, more precisely to measure engagement. It was shown that generated memes cause the same engagement as human memes that produced low engagement in the social network (historically). Thus, generated memes are less engaging than random memes created by humans.

Keywords: content generation, computational social science, memes generation, Reddit, social networks, social media interaction

Procedia PDF Downloads 144

Authors: Bensacia Nabila, Hadj-Ziane Amel, Sefah Karima

Abstract:

Carbon nanocomposites have received more attention in the last years in view of their special properties such as low density, high specific surface area, and thermal and mechanical stability. Taking into account the importance of these materials, many studies aimed at improving the synthesis process have been conducted. However, the presence of impurities could affect significantly the properties of these materials, and the characterization of these compounds is an important challenge to assure the quality of the new carbon nanocomposites. The present study aims to develop a new recyclable decontaminating material for dyes removal. This new material consists of an active element based on carbon nanotubes wrapped in a microcapsule of iron oxide. The adsorbent is characterized by Transmission electron microscopy, X-ray diffraction and the surface area was measured by the BET method.

Keywords: carbon nanocomposite, chitozen, elimination, dyes

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Authors: Haider Aamir, Muhammad Ali Khalid

Abstract:

Electricity harvesting speed bump (EHSB) is speed breaker of conventional shape, but the difference is that it is not fixed, rather it moves up and down, and electricity can be generated from its vibrating motion. This speed bump consists of an upper cover which will move up and down, a shaft mechanism which will be used to drive the generator and a rack and pinion mechanism which will connect the cover and shaft. There is a spring mechanism to return the cover to its initial state when a vehicle has passed over the bump. Produced energy in the past was up to 80 Watts. For this purpose, a clutch mechanism is used so that both the up-down movements of the cover can be used to drive the generator. Mechanical Motion Rectifier (MMR) mechanism ensures the conversion of both the linear motions into rotational motion which is used to drive the generator.

Keywords: electricity harvesting, generator, rack and pinion, stainless steel shaft

Procedia PDF Downloads 275