Search results for: tensile stress

Authors: Abdelkader Soumaya, Noureddine Ben Ayed, Ali Kadri, Said Maouche, Hayet Khayati Ammar, Ahmed Braham

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The historic sites of Bulla Regia and Chemtou are among the most important archaeological monuments in northwestern Tunisia, which flourished as large, wealthy settlements during the Roman and Byzantine periods (2nd to 7th centuries AD). An archaeoseismological study provides the first indications about the impact of a possible ancient strong earthquake in the destruction of these cities. Based on previous archaeological excavation results, including numismatic evidence, pottery, economic meltdown and urban transformation, the abrupt ruin and destruction of the cities of Bulla Regia and Chemtou can be bracketed between 613 and 647 AD. In this study, we carried out the first attempt to use the analysis of earthquake archaeological effects (EAEs) that were observed during our field investigations in these two historic cities. The damage includes different types of EAEs: folds on regular pavements, displaced and deformed vaults, folded walls, tilted walls, collapsed keystones in arches, dipping broken corners, displaced-fallen columns, block extrusions in walls, penetrative fractures in brick-made walls and open fractures on regular pavements. These deformations are spread over 10 different sectors or buildings and include 56 measured EAEs. The structural analysis of the identified EAEs can indicate an ancient destructive earthquake that probably destroyed the Bulla Regia and Chemtou archaeological sites. We then analyzed these measurements using structural geological analysis to obtain the maximum horizontal strain of the ground (e.g., S ₕₘₐₓ) on each building-oriented damage. After the collection and analysis of these strain datasets, we proceed to plot the orientation of Sₕₘₐₓ trajectories on the map of the archaeological site (Bulla Regia). We concluded that the obtained Sₕₘₐₓ trajectories within this site could then be related to the mean direction of ground motion (oscillatory movement of the ground) triggered by a seismic event, as documented for some historical earthquakes across the world. These Sₕₘₐₓ orientations closely match the current active stress field, as highlighted by some instrumental events in northern Tunisia. In terms of the seismic source, we strongly suggest that the reactivation of a neotectonic strike-slip fault trending N50E must be responsible for this probable historic earthquake and the recent instrumental seismicity in this area. This fault segment, affecting the folded quaternary deposits south of Jebel Rebia, passes through the monument of Bulla Regia. Stress inversion of the observed and measured data along this fault shows an N150 - 160 trend of Sₕₘₐₓ under a transpressional tectonic regime, which is quite consistent with the GPS data and the state of the current stress field in this region.

Keywords: NW Tunisia, archaeoseismology, earthquake archaeological effect, bulla regia - Chemtou, seismotectonic, neotectonic fault

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Authors: Monika Simkute-Bukante

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Teachers significantly influence student achievements, personal development, and academic success. Consequently, they are subject to heightened expectations and scrutiny from governments, school administrations, parents, and even students. Increasing responsibilities and pressures impact teachers’ professional well-being, contributing to a global trend of increased teacher turnover and shortages due to stress and heavy workloads. Given the critical role of teachers in educating young people, it is essential to implement strategies to retain them. School administrations are pivotal in creating an environment conducive to optimal performance. However, there remains a gap in understanding how school administration leadership impacts teachers' professional well-being and its potential for improvement. This research aims to define teacher professional well-being, identify its attributes, and explore the factors influencing it, with a particular focus on the role of school administration. Employing the concept analysis method, this study reviews scholarly publications from 2019 to 2024 to articulate the components of teacher professional well-being. The findings highlight key attributes of teacher well-being, including self-efficacy, work engagement, job satisfaction, relationships with colleagues and students, support from administration, work autonomy, school climate, time pressure, workload, resilience, stress, burnout, and turnover intentions. The analysis demonstrates that school administration leadership directly affects these aspects by providing support in challenging situations, empowering teachers, offering recognition, facilitating open communication, and ensuring autonomy at work. In conclusion, the research shows that teachers' professional well-being is heavily dependent on relationships with school administration, colleagues, and students, as well as the overall school climate. It suggests that by enhancing these elements, school leaders can significantly improve teacher professional well-being. Recommendations are made for developing strategies to support these relationships, thereby fostering an environment that enhances teacher retention and effectiveness.

Keywords: concept analysis, teacher professional well-being, school administration leadership, well-being factors

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Authors: Yiğit Gürler, İbrahim Şimşek, Müge Savaştaer, Ayberk Karakuş, Alper Taşdemirci

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316L steel is frequently used in the industry due to its easy formability and accessibility in sheet metal forming processes. Numerical and experimental studies are frequently encountered in the literature to examine the mechanical behavior of 316L stainless steel during the forming process. 316L stainless steel is the most common material used in the production of plate heat exchangers and plate heat exchangers are produced by plastic deformation of the stainless steel. The motivation in this study is to determine the appropriate material model during the simulation of the sheet metal forming process. For this reason, two different material models were examined and Ls-Dyna material cards were created using material test data. These are MAT133_BARLAT_YLD2000 and MAT093_SIMPLIFIED_JOHNSON_COOK. In order to compare results of the tensile test & hydraulic bulge test performed both numerically and experimentally. The obtained results were evaluated comparatively and the most suitable material model was selected for the forming simulation. In future studies, this material model will be used in the numerical modeling of the sheet metal forming process.

Keywords: 316L, mechanical characterization, metal forming, Ls-Dyna

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Authors: Benaouda Hemza

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This work on the characterization of structural elements in metal fiber concrete is devoted to the study of recyclability, as reinforcement for concrete, of chips resulting from the machining of steel parts. We are interested in this study to the rheological behavior of fresh chips reinforced concrete and its mechanical behavior at a young age. The evaluation of the workability with the LCL workabilimeter shows that optimal sand gravel ratios (S/G) are S/G=0.8, and S/G=1. The study of the content chips (W%) influence on the workability of the concrete shows that the flow time and the S/G optimum increase with W%. For S/G=1.4, the flow time is practically insensitive to the variation of W%, the concrete behavior is similar to that of self-compacting concrete. Mechanical characterization tests (direct tension, compression, bending, and splitting) show that the mechanical properties of chips concrete are comparable to those of the two selected reference concretes (concrete reinforced with conventional fibers: EUROSTEEL fibers corrugated and DRAMIX fibers). Chips provide a significant increase in strength and some ductility in the post-failure behavior of the concrete. Recycling chips as reinforcement for concrete can be favorably considered.

Keywords: fiber concrete, chips, workability, direct tensile test, compression test, bending test, splitting test

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Authors: Salim Çalışkan, Hakan Akyüz

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Digital image correlation has been accustomed as a versatile and efficient method for measuring displacements on the article surfaces by comparing reference subsets in undeformed images with the define target subset in the distorted image. The theoretical model points out that the accuracy of the digital image correlation displacement data can be exactly anticipated based on the divergence of the image noise and the sum of the squares of the subset intensity gradients. The digital image correlation procedure locates each subset of the original image in the distorted image. The software then determines the displacement values of the centers of the subassemblies, providing the complete displacement measures. In this paper, the effect of the speckle distribution and its effect on displacements measured out plane displacement data as a function of the size of the subset was investigated. Nine groups of speckle patterns were used in this study: samples are sprayed randomly by pre-manufactured patterns of three different hole diameters, each with three coverage ratios, on a computer numerical control punch press. The resulting displacement values, referenced at the center of the subset, are evaluated based on the average of the displacements of the pixel’s interior the subset.

Keywords: digital image correlation, speckle pattern, experimental mechanics, tensile test, aluminum alloy

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Authors: Stephen Akong Takim

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This study focused on the optimization of the flexural strength of bio-composite samples of palm kernel, whelks, clams, periwinkles shells and bamboo fiber reinforced with resin for engineering applications. The aim of the study was to formulate different samples of bio-composite reinforced with resin for engineering applications and to evaluate the flexural strength of the fabricated composite. The hand lay-up technique was used for the composites produced by incorporating different percentage compositions of the shells/fiber (10%, 15%, 20%, 25% and 30%) into varied proportions of epoxy resin and catalyst. The cured samples, after 24 hours, were subjected to tensile, impact, flexural and water absorption tests. The experiments were conducted using the Taguchi optimization method L25 (5x5) with five design parameters and five level combinations in Minitab 18 statistical software. The results showed that the average value of flexural was 114.87MPa when compared to the unreinforced 72.33MPa bio-composite. The study recommended that agricultural waste, like palm kernel shells, whelk shells, clams, periwinkle shells and bamboo fiber, should be converted into important engineering applications.

Keywords: bio-composite, resin, palm kernel shells, welk shells, periwinkle shells, bamboo fiber, Taguchi techniques and engineering application

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Authors: Faisal Ananda, Junaidi Al-Husein, Oni Febriani, Juli Ardita, N. Indra, Syaari Al-Husein, A. Bukri

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Currently, concrete technology continues to grow and continue to innovate one of them using fibers. Fiber concrete has advantages over non-fiber concrete, among others, strong against the effect of shrinkage, ability to reduce crack, fire resistance, etc. In this study, concrete mix design using the procedures listed on SNI 03-2834-2000. The sample used is a cylinder with a height of 30 cm and a width of 15cm in diameter, which is used for compression and tensile testing, while the slab is 400cm x 100cm x 15cm. The fiber used is steel fiber (dramix), with the addition of 2/3 of the thickness of the slabs. The charging is done using a two-point loading. From the result of the research, it is found that the loading of non-fiber slab (0%) of the initial crack is the maximum crack that has passed the maximum crack allowed with a crack width of 1.3 mm with a loading of 1160 kg. The initial crack with the largest load is found on the 1% fiber mixed slab, with the initial crack also being a maximum crack of 0.5mm which also has exceeded the required maximum crack. In the 4% slab the initial crack of 0.1 mm is a minimal initial crack with a load greater than the load of a non-fiber (0%) slab by load1200 kg. While the maximum load on the maximum crack according to the applicable maximum crack conditions, on the 5% fiber mixed slab with a crack width of 0.32mm by loading 1250 kg.

Keywords: crack, dramix, fiber, load, slab

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Authors: Ammari Abdelhammid

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This work on the characterization of structural elements in metal fiber concrete is devoted to the study of recyclability, as reinforcement for concrete, of chips resulting from the machining of steel parts. We're interested in this study to the Rheological behavior of fresh chips reinforced concrete and its mechanical behavior at a young age. The evaluation of the workability with the LCL workabilimeter shows that optimal sand gravel ratios ( S/G) are S/G = 0.8 and S/G = 1. The study of the content chips (W%) influence on the workability of the concrete shows that the flow time and the S/G optimum increase with W%. For S/G = 1.4, the flow time is practically insensitive to the variation of W%, the concrete behavior is similar to that of self-compacting concrete. Mechanical characterization tests (direct tension, compression, bending, and splitting) show that the mechanical properties of chips concrete are comparable to those of the two selected reference concretes (concrete reinforced with conventional fibers: Eurosteel fibers corrugated and Dramix fibers). Chips provide a significant increase in strength and some ductility in the post-failure behavior of the concrete. Recycling chips as reinforcement for concrete can be favorably considered.

Keywords: fiber concrete, chips, workability, direct tensile test, compression test, bending test, splitting test

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Authors: Weili Shao, Qian Wang, Jianxin He

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Recently, the applications of graphene oxide in fabricating scaffolds for bone tissue engineering have been received extensive concern. In this work, poly l-lactic/graphene oxide composite nanofibers were successfully fabricated by electrospinning. The morphology structure, porosity and mechanical properties of the composite nanofibers were characterized using different techniques. And mouse mesenchymal stem cells were cultured on the composite nanofiber scaffolds to assess their suitability for bone tissue engineering. The results indicated that the composite nanofiber scaffolds had finer fiber diameter and higher porosity as compared with pure poly l-lactic nanofibers. Furthermore, incorporation of graphene oxide into the poly l-lactic nanofibers increased protein adsorptivity, boosted the Young’s modulus and tensile strength by nearly 4.2-fold and 3.5-fold, respectively, and significantly enhanced adhesion, proliferation, and osteogenesis in mouse mesenchymal stem cells. The results indicate that composite nanofibers could be excellent and versatile scaffolds for bone tissue engineering.

Keywords: poly l-lactic, graphene oxide, osteogenesis, bone tissue engineering

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Authors: Sathapath Kilaso

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Nowadays people who live in the city tend to have a pet in order to relief the loneliness more than usual. It can be observed by the growth of the local pet industry. But the essentials of lifestyle of the urban people which is restricted by time and work might not allow the owner to take care of the pet properly. So this article will be about how to develop the prototype of pet care monitoring with Arduino Microcontroller. This prototype can be used to monitor the pet and its environment around the pet such as temperature (both pet’s temperature and outside temperature), humidity, food’s quantity, air’s quality and also be able to reduce the stress of the pet. This prototype can report the result back to the owner via online-channel such as website etc.

Keywords: pet care, Arduino Microcontroller, monitoring, prototype

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Authors: Peter Mc Coll, Alberto Caro, Chiara Gandolfo, Montserrat Labbe, Francisca Schnaidt, Michela Palazzi

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Self-esteem and emotional intelligence are variables that are related to people's nutritional status. Self-esteem may be at low levels in people living with obesity, while emotional intelligence can play an important role in the way people living with obesity cope. The objective of the study was to measure the association between self-esteem and emotional intelligence to nutritional status in adolescent population. Methodology: A cross-sectional study was carried out with 179 adolescent schoolchildren between 13 and 19 years old from a public school. The objective was to evaluate nutritional status; weight and height were measured by calculating the body mass index and Z score. Self-esteem was evaluated using the Coopersmith Self-esteem Inventory adapted by Brinkmann and Segure. Emotional intelligence was measured using the Emotional Quotient Inventory: short, by Bar On, adapted questionnaire, translated into Spanish by López Zafra. For statistical analysis: Pearson's Chi-square test, Pearson's correlation, and odd ratio calculation were used, with a p value at a significance level < 5%. Results: The study group was composed of 71% female and 29% male. The nutritional status was distributed as eutrophic 41.9%, overweight 20.1%, and obesity 21.1%. In relation to self-esteem, 44.1% presented low and very low levels, without differences by gender. Emotional intelligence was distributed: low 3.4%, medium 81%, and high 13.4% -no differences according to gender. The association between nutritional status (overweight and obesity) with low and very low self-esteem, an odds ratio of 2.5 (95% CI 1.12 – 5.59) was obtained with a p-value = 0.02. The correlation analysis between the intrapersonal sub-dimension emotional intelligence scores and the Z score of nutritional status presented a negative correlation of r = - 0.209 with a p-value < 0.005. The correlation between emotional intelligence subdimension stress management with Z score presented a positive correlation of r = 0.0161 with a p-value < 0.05. In conclusion, the group of adolescents studied had a high prevalence of overweight and obesity, a high prevalence of low self-esteem, and a high prevalence of average emotional intelligence. Overweight and obese adolescents were 2.5 times more likely to have low self-esteem. As overweight and obesity increase, self-esteem decreases, and the ability to manage stress increases.

Keywords: self-esteem, emotional intelligence, obesity, adolescent, nutritional status

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Authors: Rudy Djamaluddin, Arbain Tata, Rita Irmawaty

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The study conducted a simulation of the effect of sea water to the bonding capacity of GFRP sheet on the concrete beams using a simulation tank. As it well known that, fiber reinforced polymer (FRP) has been applied to many purposes for civil engineering structures not only for new structures but also for strengthening of the deteriorated structures. The FRP has advantages such as its corrosion resistance, as well as high tensile strength, to weight ratio. Glass composed FRP (GFRP) sheet is most commonly used due to its relatively lower cost compared to the other FRP materials. GFRP sheet is applied externally by bonding it on the concrete surface. Many studies have been done to investigate the bonding of GFRP sheet. However, it is still very rarely studies on the effect of sea water to the bonding capacity of GFRP sheet on the strengthened beams due to flexural loadings. This is important to be clarified for the wider application of GFRP sheet especially on the flexural structure that directly contact to the sea environment. To achieve the objective of the study, a series of concrete beams strengthened with GFRP sheet on extreme tension surface were prepared. The beams then were stored on the sea water tank for six months. Results indicated the bonding capacity decreased after six months exposed to the sea water.

Keywords: GFRP sheet, sea water, concrete beams, bonding

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Authors: B. Medjadji, L. Aminallah, B. Serier, M. Benlebna

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In this study, the finite element method in 3-D is used to calculate the integral J in the semi-elliptical crack in a pipe subjected to internal pressure. The stress-strain curve of the pipe has been determined experimentally. The J-integral was calculated in two fronts crack (Ф = 0 and Ф = π/2). The effect of the configuration of the crack on the J integral is analysed. The results show that an external longitudinal crack in a pipe is the most dangerous. It also shows that the increase in the applied pressure causes a remarkable increase of the integral J. The effect of the depth of the crack becomes important when the ratio between the depth of the crack and the thickness of the pipe (a / t) tends to 1.

Keywords: J integral, pipeline, crack, MEF

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Authors: Constance Singo, Choja Oduaran

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Child mental disorders are strongly associated with different forms of challenges, including behavioural problems. The burden of care for children with a mental disorder is high and put primary caregivers, parents in particular, at risk of poor mental wellbeing. Understanding the experience of parents of children with mental disorders is crucial to developing a relevant intervention to assist them to attain optimal mental wellbeing. The aim of this study was to explore the experiences of parents of children with conduct disorder by focussing on the psychological and social stress experience of the parents in raising and caring for their children with conduct disorder. A qualitative research approach, using in-depth interview was utilized in this study. Purposive and snowballing sampling techniques were used to select 9 parents of children with conduct disorder in Thulamela Municipality, Limpopo Province of South Africa. Participants comprising of 2 males and 7 females aged between 30 years and 49 years were interviewed individually at scheduled appointment in-home setting. Interviews were conducted in both English and Setswana language. Data collected in Setswana language were translated to English by 'expert in language translation'. Ethical approval was obtained from appropriate authority before data collection. Thematic analysis was conducted to analyse the collected data. The findings identified anger, fear, depressive symptoms, denial, and suicidal ideation as predominant psychological experiences of the parents. Furthermore, deteriorated interpersonal relationships with family and community members, financial stress, and stigma emerged as social problems being the experience of the parents. It was concluded that parents of children with conduct disorder are highly traumatized by the challenges of caring for their children. We recommend professional engagement in terms of counselling service to support the parents. There is also a need for massive enlightenment programmes for members of the community in order to support the parents of children with child mental disorders.

Keywords: conduct disorder, parents, psychosocial experiences, South Africa

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Authors: Hasan Şahan Arel

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In this study, literature related to the replacement of cement with waste marble and the use of waste marble as an aggregate in concrete production was examined. Workability of the concrete decreased when marble powder was used as a substitute for fine aggregate. Marble powder contributed to the compressive strength of concrete because of the CaCO₃ and SiO₂ present in the chemical structure of the marble. Additionally, the use of marble pieces in place of coarse aggregate revealed that this contributed to the workability and mechanical properties of the concrete. When natural standard sand was replaced with marble dust at a ratio of 15% and 75%, the compressive strength and splitting tensile strength of the concrete increased by 20%-26% and 10%-15%, respectively. However, coarse marble aggregates exhibited the best performance at a 100% replacement ratio. Additionally, there was a greater improvement in the mechanical properties of concrete when waste marble was used in a coarse aggregate form when compared to that of when marble was used in a dust form. If the cement was replaced with marble powder in proportions of 20% or more, then adverse effects were observed on the compressive strength and workability of the concrete. This study indicated that marble dust at a cement-replacement ratio of 5%-10% affected the mechanical properties of concrete by decreasing the global annual CO₂ emissions by 12% and also lowering the costs from US$40/m³ to US$33/m³.

Keywords: cement production, concrete, CO2 emission, marble, mechanical properties

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Authors: James Patrick A. Diaz, Raul E. Ramboyong

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Background: Hypertensive response during maximal exercise test provides important information on the level of blood pressure control and evaluation of treatment. Method: A single center retrospective descriptive study was conducted among 117 young (aged 20 to 40) and middle age (aged 40 to 65) hypertensive patients, who underwent treadmill stress test. Currently on maintenance frontline medication either monotherapy (Angiotensin-converting enzyme inhibitor/Angiotensin receptor blocker [ACEi/ARB], Calcium channel blocker [CCB], Diuretic - Hydrochlorthiazide [HCTZ]) or combination therapy (ARB+CCB, ARB+HCTZ), who attained a maximal exercise on treadmill stress test (TMST) with hypertensive response (systolic blood pressure: male >210 mm Hg, female >190 mm Hg, diastolic blood pressure >100 mmHg, or increase of >10 mm Hg at any time during the test), on Bruce and Modified Bruce protocol. Exaggerated blood pressure response during exercise (systolic [SBP] and diastolic [DBP]), peak exercise blood pressure (SBP and DBP), recovery period (SBP and DBP) and test for ischemia and their antihypertensive medication/s were investigated. Analysis of variance and chi-square test were used for statistical analysis. Results: Hypertensive responses on maximal exercise test were seen mostly among female population (P < 0.000) and middle age (P < 0.000) patients. Exaggerated diastolic blood pressure responses were significantly lower in patients who were taking CCB (P < 0.004). A longer recovery period that showed a delayed decline in SBP was observed in patients taking ARB+HCTZ (P < 0.036). There were no significant differences in the level of exaggerated systolic blood pressure response and during peak exercise (both systolic and diastolic) in patients using either monotherapy or combination antihypertensives. Conclusion: Calcium channel blockers provided lower exaggerated diastolic BP response during maximal exercise test in hypertensive middle age patients. Patients on combination therapy using ARB+HCTZ exhibited a longer recovery period of systolic blood pressure.

Keywords: antihypertensive, exercise test, hypertension, hyperytensive response

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Authors: Khadiza Akter, Tammy Greer, Raegan Bishop

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An in-depth study of the psycho-social effects of gynecological health disparities among immigrant women in the USA is the goal of this integrative review paper. Immigrant women frequently encounter unique obstacles that have severe psycho-social repercussions when it comes to receiving high-quality gynecological treatment. The review investigates the interaction of psychological, sociological, and health factors that affect the psycho-social effects that immigrant women experience in recognition of the significance of addressing these imbalances. The difficulties that immigrant women face in providing high-quality gynecological treatment in the USA are examined in this study. These difficulties are caused by a variety of psychological issues, including acculturation stress and stigma, as well as by social problems like prejudice, language hurdles, and cultural norms. Additionally, variations in healthcare access and affordability have a role. This study highlights the particular challenges that immigrant women have in receiving high-quality gynecological treatment in the United States. These difficulties are caused by both social problems like language obstacles, cultural norms, and biases, as well as psychological ones like acculturation stress and stigma. Additionally, variations in gynecological care for immigrant women are greatly influenced by variances in healthcare availability and price. To find pertinent research looking at the psychological effects of gynecological health disparities among immigrant women in the USA, a thorough search of numerous databases was done. Numerous approaches, including mixed, quantitative, and qualitative ones, were used in the studies. The important findings from various investigations were extracted and synthesized after they underwent a careful evaluation. In order to lessen these discrepancies and enhance the overall well-being of immigrant women, healthcare professionals, legislators, and researchers must collaborate to create specialized treatments, regulations, and health system reforms.

Keywords: cultural barriers, gynecological health disparities, health care access, immigrant women, mental health, psycho-social consequences, social stigma

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Authors: Seham Samir Soliman, Ahmed A.Suliman, Khaled Fathy, Ahmed A. Sedik

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Cyclophosphamide (CP), an antineoplastic drug, has been found to induce reproductive damage. It is essential to develop approaches aimed at safeguarding ovarian tissue integrity in women experiencing reproductive toxicity as a result of chemotherapy. The current study was conducted to assess the impact of an extract derived from Moringa oleifera (M. oleifera) leaves on ovarian damage produced by CP. A total of 32 female Wistar Albino rats, which were in a healthy cycling state, were randomly separated into 4 groups, with every group contains 8 rats. The first group was administered intraperitoneal (i.p.) saline. The second group was administered a solitary intraperitoneal dosage of cyclophosphamide (200 mg/kg). The third one received M. oleifera extract (150 mg/kg orally) for 20 days, followed by i.p. of CP on the last day of the experiment. The fourth group received M. oleifera extract (250 mg/kg orally) for 20 days, followed by i.p. of CP on the last day of the experiment. Hormonal assessments, including luteinizing hormone (LH), estrogen (ES), and follicle-stimulating hormone (FSH), were performed 24 hours after CP administration. In addition, evaluating the antioxidant status and inflammatory response against CP. Moreover, conducting detailed histopathological and ultra-structural pictures of the ovary. Our findings reported that rats intoxicated with CP exhibited elevated levels of FSH, LH, malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α), and a decrease in E₂, and glutathione (GSH) levels. Pre-treatment with M. oleifera extract (250 mg/kg orally) ameliorated the disturbance in hormonal changes, oxidative stress indices, and the levels of pro-inflammatory mediators. Also, the histopathological and ultra-structural pictures of the ovaries were improved significantly in rats. In conclusion, M. oleifera extract possesses a significant protective role against CP-induced acute reproductive toxicity via modulating the values of FSH, LH, E₂ and quenching the release of reactive oxygen species and inflammatory mediators in female rats.

Keywords: cyclophosphamide, Moringa oleifera, ovarian function, oxidative stress, pro-inflammatory mediators

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Authors: Lun Lou, Jintu Fan

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While personal protective equipment (PPE) prevents the healthcare personnel from exposing to harmful surroundings, it creates a barrier to the dissipation of body heat and perspiration, leading to severe heat stress during prolonged exposure, especially in hot environments. It has been found that most of the existed personal cooling strategies have limitations in achieving effective cooling performance with long duration and lightweight. This work aimed to develop a lightweight (<1.0 kg) and less expensive wearable air cooling and dehumidifying system (WCDS) that can be applied underneath the protective clothing and provide 50W mean cooling power for more than 5 hours at 35°C environmental temperature without compromising the protection of PPE. For the WCDS, blowers will be used to activate an internal air circulation inside the clothing microclimate, which doesn't interfere with the protection of PPE. An air cooling and dehumidifying chamber (ACMR) with a specific design will be developed to reduce the air temperature and humidity inside the protective clothing. Then the cooled and dried air will be supplied to upper chest and back areas through a branching tubing system for personal cooling. A detachable ice cooling unit will be applied from the outside of the PPE to extract heat from the clothing microclimate. This combination allows for convenient replacement of the cooling unit to refresh the cooling effect, which can realize a continuous cooling function without taking off the PPE or adding too much weight. A preliminary thermal manikin test showed that the WCDS was able to reduce the microclimate temperature inside the PPE averagely by about 8°C for 60 minutes when the environmental temperature was 28.0 °C and 33.5 °C, respectively. Replacing the ice cooling unit every hour can maintain this cooling effect, while the longest operation duration is determined by the battery of the blowers, which can last for about 6 hours. This unique design is especially helpful for the PPE users, such as health care workers in infectious and hot environments when continuous cooling and dehumidifying are needed, but the change of protective clothing may increase the risk of infection. The new WCDS will not only improve the thermal comfort of PPE users but can also extend their safe working duration.

Keywords: personal thermal management, heat stress, ppe, health care workers, wearable device

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Authors: T. Boonkang, C. Santhaweesuk, N. Pianthong, P. Neeramon, A. Phimhlo, S. Bangphan

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The objective of this research was to apply metakaolin from northeast of Thailand as a binder in the casting process of rice polishing cylinder in replacement of the imported calcined magnesite cement and to reduce the production cost of the cylinder. Metakaolin was obtained from three different regions (Udon Thani, Nakhon Phanom, and Ubon Ratchathani). The design of experiment analysis using the MINITAB Release 14 based on the compressive strength and tensile strength testing was conducted. According to the analysis results, it was found that the optimal proportions were calcined magnesite cement: metakaolin from Udon Thani, Nakhon Phanom and Ubon Ratchathani equal to 63:37, 71:29, and 100:0, respectively. When used this formula to cast the cylinder and test the rice milling, it was found that the average broken rice percent was 32.52 and 38.29 for the cylinder contained the metakaolin from Udon Thani and Nakhon Phanom, respectively, which implied that the cylinder which contained the metakaolin from Udon Thani has higher efficiency than the cylinder which contained the metakaolin from Nakhon Phanom at 0.05 level of statistical significance. Whereas, the average wear rate of cylinder from both resources were 7.27 and 6.53 g/h, respectively.

Keywords: binder, casting, metakaolin, rice polishing cylinder

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Authors: E. T. Carvalho Filho, J. T. N. Medeiros, L. G. Martinez

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Residual stresses are self equilibrating in a rigid body that acts on the microstructure of the material without application of an external load. They are elastic stresses and can be induced by mechanical, thermal and chemical processes causing a deformation gradient in the crystal lattice favoring premature failure in mechanicals components. The search for measurements with good reliability has been of great importance for the manufacturing industries. Several methods are able to quantify these stresses according to physical principles and the response of the mechanical behavior of the material. The diffraction X-ray technique is one of the most sensitive techniques for small variations of the crystalline lattice since the X-ray beam interacts with the interplanar distance. Being very sensitive technique is also susceptible to variations in measurements requiring a study of the factors that influence the final result of the measurement. Instrumental, operational factors, form deviations of the samples and geometry of analyzes are some variables that need to be considered and analyzed in order for the true measurement. The aim of this work is to analyze the sources of errors inherent to the residual stress measurement process by X-ray diffraction technique making an interlaboratory comparison to verify the reproducibility of the measurements. In this work, two specimens were machined, differing from each other by the surface finishing: grinding and polishing. Additionally, iron powder with particle size less than 45 µm was selected in order to be a reference (as recommended by ASTM E915 standard) for the tests. To verify the deviations caused by the equipment, those specimens were positioned and with the same analysis condition, seven measurements were carried out at 11Ψ tilts. To verify sample positioning errors, seven measurements were performed by positioning the sample at each measurement. To check geometry errors, measurements were repeated for the geometry and Bragg Brentano parallel beams. In order to verify the reproducibility of the method, the measurements were performed in two different laboratories and equipments. The results were statistically worked out and the quantification of the errors.

Keywords: residual stress, x-ray diffraction, repeatability, reproducibility, error analysis

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Authors: Marzieh Zarei

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Well instability is one of the most fundamental challenges faced by the oil and gas industry. Well wall stability analysis is a gap to be filled in the oil industry. The collection of static data such as well logging leads to the construction of a geomechanical numerical model, which will help in assessing the probable risks in future drilling. In this paper, geomechanical model was designed, and mechanical properties of the rock was determined at all points of the model. It was found the safe mud window was determined and the minimum and maximum mud pressures were determined in the ranges of 70-60 MPa and 110-100 MPa, respectively.

Keywords: geomechanics, numerical model, well stability, in-situ stress, underbalanced drilling

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Authors: Josef Novák, Alena Kohoutková, Vladimír Křístek, Jan Vodička

Abstract:

Numerical analysis software belong to the main tools for simulating the real behavior of various concrete structures and elements. In comparison with experimental tests, they offer an affordable way to study the mechanical behavior of structures under various conditions. The contribution deals with a precast element of an innovative airfield pavement system which is being developed within an ongoing scientific project. The proposed system consists a two-layer surface course of precast concrete panels positioned on a two-layer base of fiber-reinforced concrete with recycled aggregate. As the panels are supposed to be installed directly on the hardened base course, imperfections at the interface between the base course and surface course are expected. Considering such circumstances, three various behavior patterns could be established and considered when designing the precast element. Enormous costs of full-scale experiments force to simulate the behavior of the element in a numerical analysis software using finite element method. The simulation was conducted on a nonlinear model in order to obtain such results which could fully compensate results from the experiments. First, several loading schemes were considered with the aim to observe the critical one which was used for the simulation later on. The main objective of the simulation was to optimize reinforcement of the element subject to quasi-static loading from airplanes. When running the simulation several parameters were considered. Namely, it concerns geometrical imperfections, manufacturing imperfections, stress state in reinforcement, stress state in concrete and crack width. The numerical simulation revealed that the precast element should be heavily reinforced to fulfill all the demands assumed. The main cause of using high amount of reinforcement is the size of the imperfections which could occur at real structure. Improving manufacturing quality, the installation of the precast panels on a fresh base course or using a bedding layer underneath the surface course belong to the main steps how to reduce the size of imperfections and consequently lower the consumption of reinforcement.

Keywords: nonlinear analysis, numerical simulation, precast concrete, pavement

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Authors: Didik Sugiyanto

Abstract:

Conditions that often occur in the framework of a particular vehicle at a car is a collision or collision with another object, an example of such damage is to the frame or chassis for the required design framework that is able to absorb impact energy. Characteristics of the material are influenced by the value of the stiffness of the material that need to be considered in choosing the material properties of the material. To obtain material properties that can be adapted to the experimental conditions tested the tensile and compression testing. In this study focused on the chassis at an angle of 150, 300, and 450. It is based on field studies that vehicle primarily for freight cars have a point of order light between 150 to 450. Research methods include design tools, design framework, procurement of materials and experimental tools, tool-making, the manufacture of the test framework, and the testing process, experiment is testing the power of the press to know the order. From this test obtained the maximum force on the corner of 150 was 569.76 kg at a distance of 16 mm, angle 300 is 370.3 kg at a distance of 15 mm, angle 450 is 391.71 kg at a distance of 28 mm. After reaching the maximum force the order will occur collapse, followed by a decrease in the next distance. It can be concluded that the greatest strain energy occurs at an angle of 150. So it is known that the frame at an angle of 150 produces the best level of security.

Keywords: buckling, collapse, body frame, vehicle

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Authors: Abhinav Srivastava, Hima Harode, Chandan Kumar Saha

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The principal ingredient of an optical fiber is quartz glass. The quality of the optical fiber decreases if impure foreign substances are attached to its preform surface. If residual strain inside a preform is significant, it cracks with a small impact during drawing or transporting. Furthermore, damages and unevenness on the surface of an optical fiber base material break the fiber during drawing. The present work signifies that chlorine pre-treatment enhances mechanical properties of the optical fiber glass. FTIR (Fourier-Transform Infrared Spectroscopy) results show that chlorine gas chemically modifies the structure of silica clad; chlorine is known to soften glass. Metallic impurities on the preform surface likely formed volatile metal chlorides due to chlorine pretreatment at elevated temperature. The chlorine also acts as a drying agent, and therefore the preform surface is anticipated to be water deficient and supposedly avoids particle adhesion on the glass surface. The Weibull analysis of long length tensile strength demarcates a substantial shift in its knee. The higher dynamic fatigue n-value also indicated surface crack healing.

Keywords: mechanical strength, optical fiber glass, FTIR, Weibull analysis

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Authors: Zaoiai Said, Makani Abdelkadir, Tafraoui Ahmed

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Concrete material suffers from a relatively low tensile strength and deformation capacity is limited. Such defects of the concrete are very fragile and sensitive to shrinkage cracking materials. The Self- Compacting Concrete (SCC) are highly fluid concretes whose implementation without vibration. This material replaces traditional vibrated concrete mainly seen techno-economic interest it presents. The SCC has several advantages which are at the origin of their development crunching. The research is therefore to conduct a comparison in terms of rheological and mechanical performance between different formulations to find the optimal dosage for rubber granulates. Through this research, we demonstrated that it is possible to make different settings SCC composition having good rheological and mechanical properties. This study also showed that the substitution of natural coarse aggregates (NA) by coarse rubber aggregates (RA) in the composition of the SCC, contributes to a slight variation of workability in the fresh state parameters still remaining in the field of SCC required by the AFGC recommendations. The experimental results show that the compressive strengths of SCC decreased slightly by substituting NA by RA. Finally, the decrease in free shrinkage is proportional to the percentage of RA incorporated into the composition of concrete. This reduction is mainly due to the improvement of the deformability of these materials.

Keywords: self-compacting concrete, coarse rubber aggregate, rheological characterization, mechanical performance, shrinkage

Procedia PDF Downloads 287

Authors: Minsu Kim, Hae-Chang Cho, Jae Hoon Chung, Inwook Heo, Kang Su Kim

Abstract:

For safe design of the UHPC flexural members, accurate estimations of their shear strengths are very important. However, since the shear strengths are significantly affected by various factors such as tensile strength of concrete, shear span to depth ratio, volume ratio of steel fiber, and steel fiber factor, the accurate estimations of their shear strengths are very challenging. In this study, therefore, the Adaptive Neuro-Fuzzy System (ANFIS), which has been widely used to solve many complex problems in engineering fields, was introduced to estimate the shear strengths of UHPC flexural members. A total of 32 experimental results has been collected from previous studies for training of the ANFIS algorithm, and the well-trained ANFIS algorithm provided good estimations on the shear strengths of the UHPC test specimens. Acknowledgement: This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT & Future Planning(NRF-2016R1A2B2010277).

Keywords: ultra-high-performance concrete, ANFIS, shear strength, flexural member

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Authors: Rumana Keyani, Haleema Sadia, Asia Nosheen, Rabia Naz, Humaira Yasmin, Sidra Zahoor

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Tomato is a significant crop of the world and is one of the staple foods of Pakistan. A vast number of plant pathogens from simple viruses to complex parasites cause diseases in tomatoes but fungal infection in our country is quite high. Sometimes the symptoms are too harsh destroying the crop altogether. Countries like our own with continuously increasing massive population and limited resources cannot afford such an economic loss. There is an array of morphological, genetic, biochemical and molecular processes involved in plant resistance mechanisms to biotic stress. The study of different metabolic pathways like Jasmonic acid (JA) pathways and most importantly signaling molecules like ROS/RNS and their redoxin enzymes i.e. TRX and NRX is crucial to disease management, contributing to healthy plant growth. So, improving tolerance in crop plants against biotic stresses is a dire need of our country and world as whole. In the current study, fungal pathogenic strains Alternaria solani and Rhizoctonia solani were used to inoculate tomatoes to check the defense responses of tomato plant against these pathogens at molecular as well as phenotypic level with jasmonic acid and spermidine pretreatment. All the growth parameters (root and shoot length, dry and weight root, shoot weight measured 7 days post-inoculation, exhibited that infection drastically declined the growth of the plant whereas jasmonic acid and spermidine assisted the plants to cope up with the infection. Thus, JA and Spermidine treatments maintained comparatively better growth factors. Antioxidant assays and expression analysis through real time quantitative PCR following time course experiment at 24, 48 and 72 hours intervals also exhibited that activation of JA defense genes and a polyamine Spermidine helps in mediating tomato responses against fungal infection when used alone but the two treatments combined mask the effect of each other.

Keywords: fungal infection, jasmonic acid defence, tomato, spermidine

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Authors: Alain Rousseau, Alfred Aragones, Gilles Rougier

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The study is based on lightning and surge standards mainly the EN series 62305 for facility protection, EN series 61643 for Low Voltage Surge Protective Devices, High Voltage surge arrester standard en 60099-4 and the traction arrester standards namely EN 50526-1 and 50526-1 dealing respectively with railway applications fixed installations D.C. surge arresters and voltage limiting devices. The more severe stress for tramways installations is caused by direct lightning on the catenary line. In such case, the surge current propagates towards the various poles and sparkover the insulators leading to a lower stress. If the impact point is near enough, a significant surge current will flow towards the traction surge arrester that is installed on the catenary at the location the substation is connected. Another surge arrester can be installed at the entrance of the substation or even inside the rectifier to avoid insulation damages. In addition, surge arresters can be installed between + and – to avoid damaging sensitive circuits. Based on disturbances encountered in a substation following a lighting event, the engineering department of RATP has decided to investigate the cause of such damage and more generally to question the efficiency of the various possible protection means. Based on the example of a recent tramway line the paper present the result of a lightning study based on direct lightning strikes. As a matter of fact, the induced surges on the catenary are much more frequent but much less damaging. First, a lightning risk assessment is performed for the substations that takes into account direct lightning and induced lightning both on the substation and its connected lines such as the catenary. Then the paper deals with efficiency of the various surge arresters is discussed based on field experience and calculations. The efficiency of the earthing system used at the bottom of the pole is also addressed based on high frequency earthing measurement. As a conclusion, the paper is making recommendations for an enhanced efficiency of existing protection means.

Keywords: surge arrester, traction, lightning, risk, surge protective device

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Authors: Annunziata Albano

Abstract:

Intimate Partner Violence (IPV) and Non-Partner Sexual Violence (NPSV) are still the most common forms of interpersonal violence against women today, and numerous studies have shown how they can affect women's physical and psychological well-being, frequently leading to depression, posttraumatic stress disorder (PTSD), and substance abuse. The primary goal of Italian Anti-Violence Centres (AVCs) is to provide an appropriate context for women to embark on a personalised path out of violence by providing various services such as listening groups, psychological and legal support, housing support in collaboration with shelters, work orientation, and specific support in the case of minor children. However, their physical environment is frequently overlooked, partly because these centres are typically established in pre-existing buildings and have a limited budget. Several studies on healthcare design and mental health, on the other hand, emphasise the potential of the built environment to facilitate healing by providing a restorative setting that aids in coping with stress and traumatic experiences, investigating the positive role of natural features and sensorial qualities such as light, colours, sound, and smell. This research aims to collect and summarise the key evidence-based principles derived from a multidisciplinary literature review about interior design elements that can help women recover after their traumatic experience. Furthermore, the study examines multiple case studies of Italian AVCs through the lens of previously determined principles, to understand how and whether these guidelines have been applied and which outcomes can provide relevant insights for design practice, with an emphasis on sensory qualities, usually overlooked in favour of other requirements. The outlined guidelines may serve as a framework for various typologies of services provided to women who are the victims of interpersonal violence, such as women's crisis centres and shelters.

Keywords: anti-violence centres, environmental psychology, interior design, interpersonal violence, restorative environments

Procedia PDF Downloads 111