Search results for: equivalent concrete stress block

Authors: Alireza Gholipour, Mergen H. Ghayesh, Anthony Zander, Stephen J. Nicholls, Peter J. Psaltis

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A three-dimensional numerical model of an atherosclerotic coronary ‎artery is developed for the determination of high-risk situation and ‎hence heart attack prediction. Employing the finite element method ‎‎(FEM) using ANSYS, fluid-structure interaction (FSI) model of the ‎artery is constructed to determine the shear stress distribution as well ‎as the von Mises stress field. A flexible model for an atherosclerotic ‎coronary artery conveying pulsatile blood is developed incorporating ‎three-dimensionality, artery’s tapered shape via a linear function for ‎artery wall distribution, motion of the artery, blood viscosity via the ‎non-Newtonian flow theory, blood pulsation via use of one-period ‎heartbeat, hyperelasticity via the Mooney-Rivlin model, viscoelasticity ‎via the Prony series shear relaxation scheme, and micro-calcification ‎inside the plaque. The material properties used to relate the stress field ‎to the strain field have been extracted from clinical data from previous ‎in-vitro studies. The determined stress fields has potential to be used as ‎a predictive tool for plaque rupture and dissection.‎ The results show that stress concentration due to micro-calcification ‎increases the von Mises stress significantly; chance of developing a ‎crack inside the plaque increases. Moreover, the blood pulsation varies ‎the stress distribution substantially for some cases.‎

Keywords: atherosclerosis, fluid-structure interaction‎, coronary arteries‎, pulsatile flow

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Authors: Minu Lakra

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The present study was done on 100 (male=50 and female=50) teachers of physical education at tertiary level from Varanasi city. They were chosen according to the stratified sampling method. Data collection tool was Perceived Stress Scale: 14 items (Cohen, Kamarck and mermelstain 1983) and Quality of Life was developed by THE WHOQOL GROUP in 1991. Data was analyzed with the help of correlation. Findings explore that perceived stress and quality of life has been positively correlated in female teachers of higher education from physical education whereas in male teachers the relationship was found insignificant.

Keywords: higher education, male and female teachers , percieved stress, quality of life

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Authors: Sharib Ahmed, Mansoor Rafi, Kamran Ali Awan, Faraz Khaskhali, Amir Maqbool, Altaf Hashmi

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Medical linear accelerators (LINAC’s) used in radiotherapy treatments produce undesired neutrons when they are operated at energies above 8 MeV, both in electron and photon configuration. Neutrons are produced by high-energy photons and electrons through electronuclear (e, n) a photonuclear giant dipole resonance (GDR) reactions. These reactions occurs when incoming photon or electron incident through the various materials of target, flattening filter, collimators, and other shielding components in LINAC’s structure. These neutrons may reach directly to the patient, or they may interact with the surrounding materials until they become thermalized. A work has been set up to study the effect of different parameter on the production of neutron around the room by photonuclear reactions induced by photons above ~8 MeV. One of the commercial available neutron detector (Ludlum Model 42-31H Neutron Detector) is used for the detection of thermal and fast neutrons (0.025 eV to approximately 12 MeV) inside and outside of the treatment room. Measurements were performed for different field sizes at 100 cm source to surface distance (SSD) of detector, at different distances from the isocenter and at the place of primary and secondary walls. Other measurements were performed at door and treatment console for the potential radiation safety concerns of the therapists who must walk in and out of the room for the treatments. Exposures have taken place from Elekta Synergy® linear accelerators for two different energies (10 MV and 18 MV) for a given 200 MU’s and dose rate of 600 MU per minute. Results indicates that neutron doses at 100 cm SSD depend on accelerator characteristics means jaw settings as jaws are made of high atomic number material so provides significant interaction of photons to produce neutrons, while doses at the place of larger distance from isocenter are strongly influenced by the treatment room geometry and backscattering from the walls cause a greater doses as compare to dose at 100 cm distance from isocenter. In the treatment room the ambient dose equivalent due to photons produced during decay of activation nuclei varies from 4.22 mSv.h−1 to 13.2 mSv.h−1 (at isocenter),6.21 mSv.h−1 to 29.2 mSv.h−1 (primary wall) and 8.73 mSv.h−1 to 37.2 mSv.h−1 (secondary wall) for 10 and 18 MV respectively. The ambient dose equivalent for neutrons at door is 5 μSv.h−1 to 2 μSv.h−1 while at treatment console room it is 2 μSv.h−1 to 0 μSv.h−1 for 10 and 18 MV respectively which shows that a 2 m thick and 5m longer concrete maze provides sufficient shielding for neutron at door as well as at treatment console for 10 and 18 MV photons.

Keywords: equivalent doses, neutron contamination, neutron detector, photon energy

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Authors: Hamid Fallah

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Asphalt is generally a mixture of stone materials with continuous granulation and a binder, which is usually bitumen. Asphalt is made in different shapes according to its use. The most familiar type of asphalt is hot asphalt or hot asphalt concrete. Stone materials usually make up more than 90% of the asphalt mixture. Therefore, stone materials have a significant impact on the quality of the resulting asphalt. According to the method of application and mixing, asphalt is divided into three categories: hot asphalt, protective asphalt, and cold asphalt. Cold mix asphalt is a mixture of stone materials and mixed bitumen or bitumen emulsion whose raw materials are mixed at ambient temperature. In some types of cold asphalt, the bitumen may be heated as necessary, but other materials are mixed with the bitumen without heating. Protective asphalts are used to make the roadbed impermeable, increase its abrasion and sliding resistance, and also temporarily improve the existing asphalt and concrete surfaces. This type of paving is very economical compared to hot asphalt due to the speed and ease of implementation and the limited need for asphalt machines and equipment. The present article, which is prepared in descriptive library form, introduces asphalt, its types, characteristics, and its application.

Keywords: asphalt, type of asphalt, asphalt concrete, sulfur concrete, bitumen in asphalt, sulfur, stone materials

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Authors: Ratna Siti Khodijah, Mirzam Abdurrachman

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Gold is recovered from gold ores. Within the ores, there are not only gold but also several types of precious metals. Copper, silver, and platinum group elements (ruthenium, rhodium, palladium, rhenium, osmium, and iridium) are metals commonly found in the ores. These metals combine to form an ore because they have the same properties. It is due to their position in periodic-system-of-elements are near to gold. However, the presence of mercury in every gold ore has not been mentioned, even though it is located right next to gold in the periodic-system-of-elements and they are located in the same block, d-block. Thus, it is possible that mercury is contained in the ores. Moreover, the elements of the same group with mercury—zinc and cadmium—sometimes can be found in the ores. It is suspected that mercury can not be detected because the processing of gold ores usually using fire assay method. Before the ores melting, mercury would evaporate because it has the lowest boiling point of all precious metal in the ores. Therefore, it suggested doing research on the presence of mercury in gold ores by CVAAS method. The results of this study would obtain the amount of mercury in gold ores that should be purified. So it can be produced economically if possible.

Keywords: boiling point, d-block, fire assay, precious metal

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Authors: Zafer Sakka, Husain Al-Khaiat

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Due to social and economic considerations, owners all over the world desire to keep and use existing structures, including aging ones. However, these structures, especially those that are dear, need accurate condition assessment, and proper safety evaluation. More than half of the budget spent on construction activities in developed countries is related to the repair and maintenance of these reinforced concrete (R/C) structures. Also, periodical evaluation and assessment of relatively old concrete structures are vital and imperative. If the evaluation and assessment of structural components of a particular aging R/C structure reveal that repairs are essential for these components, these repairs should not be delayed. Delaying the repairs has the potential of losing serviceability of the whole structure and/or causing total failure and collapse of the structure. In addition, if repairs are delayed, the cost of maintenance will skyrocket as well. It can also be concluded from the above that the assessment of existing needs to receive more consideration and thought from the structural engineering societies and professionals. Ten major existing structures in Kuwait city that were constructed in the 1970s were assessed for structural reliability and integrity. Numerous concrete samples were extracted from the structural systems of the investigated buildings. This paper presents the results of the compressive strength tests that were conducted on the extracted cores. The results are compared for the buildings’ columns and beams elements and compared with the design strengths. The collected data were statistically analyzed. The average compressive strengths of the concrete cores that were extracted from the ten buildings had a large variation. The lowest average compressive strength for one of the buildings was 158 kg/cm². This building was deemed unsafe and economically unfeasible to be repaired; accordingly, it was demolished. The other buildings had an average compressive strengths fall in the range 215-317 kg/cm². Poor construction practices were the main cause for the strengths. Although most of the drawings and information for these buildings were lost during the invasion of Kuwait in 1990, however, information gathered indicated that the design strengths of the beams and columns for most of these buildings were in the range of 280-400 kg/cm². Following the study, measures were taken to rehabilitate the buildings for safety. The mean compressive strength for all cores taken from beams and columns of the ten buildings was 256.7 kg/cm². The values range was 139 to 394 kg/cm². For columns, the mean was 250.4 kg/cm², and the values ranged from 137 to 394 kg/cm². However, the mean compressive strength for the beams was higher than that of columns. It was 285.9 kg/cm², and the range was 181 to 383 kg/cm². In addition to the concrete cores that were extracted from the ten buildings, the 28-day compressive strengths of more than 24,660 concrete cubes were collected from a major ready-mixed concrete supplier in Kuwait. The data represented four different grades of ready-mix concrete (250, 300, 350, and 400 kg/cm²) manufactured between the year 2003 and 2018. The average concrete compressive strength for the different concrete grades (250, 300, 350 and 400 kg/cm²) was found to be 318, 382, 453 and 504 kg/cm², respectively, and the coefficients of variations were found to be 0.138, 0.140, 0.157 and 0.131, respectively.

Keywords: concrete compressive strength, concrete structures, existing building, statistical analysis.

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Authors: Zoe Chang, Max Williams, Gautham Das

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The purpose of this study is to evaluate the incorporation of hemp fibers (HF) in concrete. Hemp fiber reinforced concrete (HFRC) is becoming more popular as an alternative for regular mix designs. This study was done to evaluate the compressive strength of HFRC regarding mix procedure. Hemp fibers were obtained from the manufacturer and hand-processed to ensure uniformity in width and length. The fibers were added to the concrete as both wet and dry mixes to investigate and optimize the mix design process. Results indicated that the dry mix had a compressive strength of 1157 psi compared to the wet mix of 985 psi. This dry mix compressive strength was within range of the standard mix compressive strength of 1533 psi. The statistical analysis revealed that the mix design process needs further optimization and uniformity concerning the addition of HF. Regression analysis revealed the standard mix design had a coefficient of 0.9 as compared to the dry mix of 0.375, indicating a variation in the mixing process. While completing the dry mix, the addition of plain hemp fibers caused them to intertwine, creating lumps and inconsistency. However, during the wet mixing process, combining water and hemp fibers before incorporation allows the fibers to uniformly disperse within the mix; hence the regression analysis indicated a better coefficient of 0.55. This study concludes that HRFC is a viable alternative to regular mixes; however, more research surrounding its characteristics needs to be conducted.

Keywords: hemp fibers, hemp reinforced concrete, wet & dry, freeze thaw testing, compressive strength

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Authors: Lenka Bodnárová, Rudolf Hela, Michala Hubertová, Iveta Nováková

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This paper is concerning the issues of behaviour of lightweight expanded clay aggregates concrete exposed to high temperature. Lightweight aggregates from expanded clay are produced by firing of row material up to temperature 1050°C. Lightweight aggregates have suitable properties in terms of volume stability, when exposed to temperatures up to 1050°C, which could indicate their suitability for construction applications with higher risk of fire. The test samples were exposed to heat by using the standard temperature-time curve ISO 834. Negative changes in resulting mechanical properties, such as compressive strength, tensile strength, and flexural strength were evaluated. Also visual evaluation of the specimen was performed. On specimen exposed to excessive heat, an explosive spalling could be observed, due to evaporation of considerable amount of unbounded water from the inner structure of the concrete.

Keywords: expanded clay aggregate, explosive spalling, high temperature, lightweight concrete, temperature-time curve ISO 834

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Authors: Waheed Ahmad Safi, Shunichi Nakamura, Abdul Habib Ghaforzai

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Steel and concrete composite bridge with concrete filled steel I-girder (CFIG) was proposed and FEM and laboratory tests were conducted to analysis bending and shear behavior. The proposed form of structural steel I-section is mainly used at the intermediate support zone by placing infilled concrete into the top and bottom flanges of steel I-section to resist negative bending moment. The bending and shear tests were carried out to find out the significance of CFIG section. The result for test showing that the bending and shear capacity of proposed CFIG is at least 3 times and 2 times greater than conventional steel I-section (IG) respectively. Finite element study was also carried out to ensure the result for laboratory tests due to bending and shear behavior and load transfer behavior of proposed structural form. Finite element result result agreed the test result. A design example was carried out for a four-span continuous highway bridge and design method was established.

Keywords: bending strength, concrete filled steel I-girder, steel I-girder, FEM, limit states design and shear strength

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Authors: German Galvez-Garcia, Javier Albayay, Javiera Peña, Marta Lavin, George A. Michael

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The aim of this research was to investigate whether the selection of the actions needs different inhibition processes during the response selection stage. In Experiment 1, we compared the magnitude of the Spatial Stroop effect, which occurs in response selection stage, in two motor actions (lifting vs reaching) when the participants performed both actions in the same block or in different blocks (mixed block vs. pure blocks).Within pure blocks, we obtained faster latencies when lifting actions were performed, but no differences in the magnitude of the Spatial Stroop effect were observed. Within mixed block, we obtained faster latencies as well as bigger-magnitude for Spatial Stroop effect when reaching actions were performed. We concluded that when no action selection is required (the pure blocks condition), inhibition works as a unitary system, whereas in the mixed block condition, where action selection is required, different inhibitory processes take place within a common processing stage. In Experiment 2, we investigated this common processing stage in depth by limiting participants’ available resources, requiring them to engage in a concurrent auditory task within a mixed block condition. The Spatial Stroop effect interacted with Movement as it did in Experiment 1, but it did not significantly interact with available resources (Auditory task x Spatial Stroop effect x Movement interaction). Thus, we concluded that available resources are distributed equally to both inhibition processes; this reinforces the likelihood of there being a common processing stage in which the different inhibitory processes take place.

Keywords: inhibition process, motor processes, selective inhibition, dual task

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Authors: Nadjoua Bourmatte, Hacène Houari

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Glass has been indispensable to men’s life due to its properties, including pliability to take any shape with ease, bright surface, resistance to abrasion, reasonable safety and durability. Waste glass creates serious environmental problems, mainly due to the inconsistency of waste glass streams. With increasing environmental pressure to reduce solid waste and to recycle as much as possible, the concrete industry has adopted a number of methods to achieve this goal. The object of this research work is to study the effect of using recycled glass waste, as a partial replacement of fine aggregate, on the fresh and hardened properties of concrete. Recycled glass was used to replace fine aggregate in proportions of 0%, 25% and 50%. We could observe that the Glass waste aggregates are lighter than natural aggregates and they show a very low water absorption. The experimental results showed that the slump flow increased with the increase of recycled glass content. On the other hand, the compressive strength and tensile strength of recycled glass mixtures decreased with the increase in the recycled glass content. The results showed that recycled glass aggregate can successfully be used with limited level for producing concrete. The standard sand was substituted with aggregates based on glass waste for manufacturing mortars, Mortar based on glass shows a compressive strength and low bending with a 1/2 ratio with control mortar strength.

Keywords: concrete, environment, glass waste, recycling

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Authors: Ilya Vladimirovich Konevtsev, Elena Anatolievna Rodionova

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This work is devoted to the study of the impact of the methodology of flexible management in IT companies on the level of organizational and professional stress of employees. It is assumed that the level of organizational and professional stress will decrease statistically significantly, provided that the company operates in accordance with the principles of flexible methodology, including Scrum or Kanban frameworks. The professional health of employees of various companies in the modern world is a stable interest for organizational psychology and many other related disciplines. The urgency of the problem is due to the fact that professional health is an extremely important factor that ensures the well-being, involvement, and interest of an employee in the activity, which directly affects his efficiency and work results. The use of modern methodologies for managing projects, teams, and entire companies, as practice shows, largely contributes to improving the efficiency and satisfaction of employees, but it is still not clear what factors contribute to this result. The purpose of this study is largely to clarify the question of how HR management methodologies affect the professional health of company employees. The study involved 44 employees of IT companies, of which 27 are men and 17 women, where Agile management methodology is used, and 41 employees of IT companies (33 men, 8 women) where Agile is not used. As a result, it was found out that the use of Agile methodology is interrelated with low indicators of organizational stress and professional stress; however, regression analysis showed that only the Kanban framework acts as a predictor of reducing professional stress, while the level of organizational stress is statistically significantly reduced when using Scrum and Kanban.

Keywords: professional stress, organizational stress, agile, scrum, Kanban

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Authors: Jubee Varghese, Pouria Hafiz

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Increased use of lightweight concrete in the construction industry is mainly due to its reduction in the weight of the structural elements, which in turn reduces the cost of production, transportation, and the overall project cost. However, the structural application of these lightweight concrete structures is limited due to its reduced density. Hence, further investigations are in progress to study the effect of fiber inclusion in improving the mechanical properties of lightweight concrete. Incorporating structural steel fibers, in general, enhances the performance of concrete and increases its durability by minimizing its potential to cracking and providing crack arresting mechanism. In this research, Geometric and Materially Non-linear Analysis (GMNA) was conducted for Finite Element Modelling using a software known as ABAQUS, to investigate the structural behavior of lightweight concrete with and without the addition of steel fibers and shear reinforcement. 21 finite element models of beams were created to study the effect of steel fibers based on three main parameters; fiber volume fraction (Vf = 0, 0.5 and 0.75%), shear span to depth ratio (a/d of 2, 3 and 4) and ratio of area of shear stirrups to spacing (As/s of 0.7, 1 and 1.6). The models created were validated with the previous experiment conducted by H.K. Kang et al. in 2011. It was seen that the lightweight fiber reinforcement can replace the use of fiber reinforced normal weight concrete as structural elements. The effect of an increase in steel fiber volume fraction is dominant for beams with higher shear span to depth ratio than for lower ratios. The effect of stirrups in the presence of fibers was very negligible; however; it provided extra confinement to the cracks by reducing the crack propagation and extra shear resistance than when compared to beams with no stirrups.

Keywords: ABAQUS, beams, fiber-reinforced concrete, finite element, light weight, shear span-depth ratio, steel fibers, steel-fiber volume fraction

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Authors: Hasan Ziari, Hassan Fazaeli, Seyed Javad Vaziri Kang Olyaei, Asma Sadat Dabiri

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The presence of cracks in concrete pavements is a place for the ingression of corrosive substances, acids, oils, and water into the pavement and reduces its long-term durability and level of service. One of the causes of early cracks in concrete pavements is the plastic shrinkage. This shrinkage occurs due to the formation of negative capillary pressures after the equilibrium of the bleeding and evaporation rates at the pavement surface. These cracks form if the tensile stresses caused by the restrained shrinkage exceed the tensile strength of the concrete. Different climate conditions change the rate of evaporation and thus change the balance time of the bleeding and evaporation, which changes the severity of cracking in concrete. The present study examined the relationship between the balance time of bleeding and evaporation and the area of cracking in the concrete slabs using the standard method ASTM C1579 in 27 different environmental conditions by using continuous video recording and digital image analyzing. The results showed that as the evaporation rate increased and the balance time decreased, the crack severity significantly increased so that by reducing the balance time from the maximum value to its minimum value, the cracking area increased more than four times. It was also observed that the cracking area- balance time curve could be interpreted in three sections. An examination of these three parts showed that the combination of climate conditions has a significant effect on increasing or decreasing these two variables. The criticality of a single factor cannot cause the critical conditions of plastic cracking. By combining two mild environmental factors with a severe climate factor (in terms of surface evaporation rate), a considerable reduction in balance time and a sharp increase in cracking severity can be prevented. The results of this study showed that balance time could be an essential factor in controlling and predicting plastic shrinkage cracking in concrete pavements. It is necessary to control this factor in the case of constructing concrete pavements in different climate conditions.

Keywords: bleeding and cracking severity, concrete pavements, climate conditions, plastic shrinkage

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Authors: Jaylina Rana, Chanakya Arya, John Stehle

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Hybrid precast twinwall concrete units, mainly used in basement, core and crosswall construction, are now being adopted in water retaining tank structures. Their use offers many advantages compared with conventional in-situ concrete alternatives, however, the design could be optimised further via a deeper understanding of the unique load transfer mechanisms in the system. In the tank application, twinwall units, which consist of two precast concrete biscuits connected by steel lattices and in-situ concrete core, are subject to bending. Uncertainties about the degree of composite action between the precast biscuits and hence flexural performance of the units necessitated laboratory tests to investigate the interface shear resistance. Testing was also required to assess both the leakage performance and buildability of a variety of joint details. This paper describes some aspects of this novel approach to the design/construction of tank structures as well as selected results from some of the tests that were carried out.

Keywords: hybrid construction, twinwall, precast construction, composite action

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Authors: S. Summart, C. Saetiaw, T. Thosdeekoraphat, C. Thongsopa

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This article presents new current-mode oscillator circuits using CDTAs which is designed from block diagram. The proposed circuits consist of two CDTAs and two grounded capacitors. The condition of oscillation and the frequency of oscillation can be adjusted by electronic method. The circuits have high output impedance and use only grounded capacitors without any external resistor which is very appropriate to future development into an integrated circuit. The results of PSPICE simulation program are corresponding to the theoretical analysis.

Keywords: current-mode, quadrature oscillator, block diagram, CDTA

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Authors: Edward Ridyard, Vinary Varadarajan

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Background and Aims: The first year as a doctor in any country represents a major career transition in any physician's life. During this period, many physicians concentrate on obtaining clinical skills but may not obtain the important skills necessary to cope with stress. In this study we elucidate stress levels amongst FY1 doctors regarding the transitioning into specialty career choices, working in the NHS and anxiety about future career success. Methods: A prospective single blinded analysis of Foundation Year one (FY1) trainees using a non-mandatory online questionnaire was distributed. No exclusion criteria were applied. The only inclusion criteria was the doctor was in a full-time FY1 post and this was their first job in the UK. A total of n= 22 doctors were included in the study. After data collection, statistical analysis using chi-squared testing was applied. Results: The large majority of FY1 doctors (72.7%) already knew what specialty they wished to pursue (p=0.0001). With regards to their future careers 45.5% of FY1 doctors stated "above average" stress levels. The majority of FY1 doctors (64.3%) stated their stress levels working in the NHS were either "above average" or "high". Finally, 81.8% of respondents know colleagues who have been put off from pursuing specialties due to the stress of competition. Conclusions: A large majority of FY1 doctors already know at this early stage what area they would like to specialise in. With this in mind, a large proportion have above "average" levels of stress with regards to securing this future career path. The most worrying finding is that 64.3% of FY1s stated they had "above average" or "high" stress levels working in the NHS. We therefore recommend formal stress management education to be incorporated into the foundation programme curriculum.

Keywords: stress, anxiety, junior doctor, education

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Authors: Jason Ting Jing Cheng, Lee Foo Wei, Yew Ming Kun, Mo Kim Hung, Yip Chun Chieh

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This research delves into the structural characteristics of distinct construction material, rubberized lightweight foam concrete (RLFC) wall panels, which have been developed as a sustainable alternative for the construction industry. These panels are engineered with a RLFC core, possessing a density of 1150 kg/m3, which is specifically formulated to bear structural loads. The core is enveloped with high-strength fiber cement boards, selected for their superior load-bearing capabilities, and enhanced flexural strength when compared to conventional concrete. A thin bed adhesive, known as TPS, is employed to create a robust bond between the RLFC core and the fiber cement cladding. This study underscores the potential of RLFC wall panels as a viable and eco-friendly option for modern building construction, offering a combination of structural efficiency and environmental benefits.

Keywords: structural performance, rubberized concrete wall panel, fiber cement board, insulation performance

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Authors: Naser Alenezi, Ibrahim Alsakkaf, Osama Eid

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The main objective of this study is to develop an independent reliability based code for reinforced concrete (R/C) structural components and elements solely for the State of Kuwait and its neighboring countries. The proposed code will take into account the harsh Kuwait’s harsh environment, loading conditions and material strengths. The method for developing such a code is based on structural reliability theory that takes into accounts the specific geographical and the various prescribed societal environment of the Kuwait region. These methods were developed according to the following four components: (1) loads, (2) structural strength, (3) reliability analysis, and (4) achieving target reliability levels (reliability index ’s ). The final product from this study will be a design code for R/C structural elements that include beams and columns, and some other structural members. This reliability-based LRFD design code will provide appropriate, easy, fast, and economical approach for designing R/C structural elements such as, beams and columns, for both houses and bridges, and other concrete structures. In addition, this reliability-based codified design of R/C beams, columns, and, possibly, concrete slabs will improve the design and serviceability of R/C bridge and building systems in Kuwait and neighboring GCC countries. Also, it has the potential to reduce the cost of new concrete structures, as fewer materials are used with more design efficiency.

Keywords: live laod, design, evaluation, structural building

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Authors: Ramesh Bhat, Ammu Somanath, A. K. Nayanatara

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Background: The increasing prevalence of overweight and obesity is a critical public health problem for women. The negative effect of stress on memory and cognitive functions has been widely explored for decades in numerous research projects using a wide range of methodology. Deterioration of memory and other brain functions are hallmarks of Alzheimer’s disease. Estrogen fluctuations and withdrawal have myriad direct effects on the central nervous system that have the potential to influence cognitive functions. Aim: The present study aims to compare the effect of stress on the cognitive functions in overweight/obese women before and after menopause. Material and Methods: A total of 142 female subjects constituting women before menopause between the age group of 18–44 years and women after menopause between the age group of 45–60 years were included in the sample. Participants were categorized into overweight/obese groups based on the body mass index. The Perceived Stress Scale (PSS) the major tool was used for measuring the perception of stress. Based on the stress scale measurement each group was classified into with stress and without stress. Addenbrooke’s cognitive Examination-III was used for measuring the cognitive functions. Results: Premenopausal women with stress showed a significant (P<0.05) decrease in the cognitive parameters such as attention and orientation Fluency, language and visuospatial ability. Memory did not show any significant change in this group. Whereas, in the postmenopausal stressed women all the cognitive functions except fluency showed a significant (P<0.05) decrease after menopause stressed group. Conclusion: Stress is a significant factor on the cognitive functions of obese and overweight women before and after menopause. Practice of Yoga, Encouragement in activities like gardening, embroidery, games and relaxation techniques should be recommended to prevent stress. Insights into the neurobiology before and after menopause can be gained from future studies examining the effect on the HPA axis in relation to cognition and stress.

Keywords: cognition, stress, premenopausal, body mass index

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Authors: T. S. Serniabat, M. N. N. Khan, M. F. M. Zain

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As climate change and environmental pressures are now well established as major international issues, to which governments, businesses and consumers have to respond through more environmentally friendly and aware practices, products and policies; the need to develop alternative sustainable construction materials, reduce greenhouse gas emissions, save energy, look to renewable energy sources and recycled materials, and reduce waste are just some of the pressures impacting significantly on the construction industry. The utilization of waste materials (slag, fly ash, glass beads, plastic and so on) in concrete manufacturing is significant due to engineering, financial, environmental and ecological importance. Thus, utilization of waste materials in concrete production is very much helpful to reach the goal of the sustainable construction. Therefore, this study intends to use glass beads in concrete production. The paper reports on the performance of 9 different concrete mixes containing different ratios of glass crushed to 5 mm - 20 mm maximum size and glass marble of 20 mm size as coarse aggregate .Ordinary Portland cement type 1 and fine sand less than 0.5 mm were used to produce standard concrete cylinders. Compressive strength tests were carried out on concrete specimens at various ages. Test results indicated that the mix having the balanced ratio of glass beads and round marbles possess maximum compressive strength which is 3888.68 psi, as glass beads perform better in bond formation but have lower strength, on the other hand marbles are strong in themselves but not good in bonding. These mixes were prepared following a specific W/C and aggregate ratio; more strength can be expected to achieve from different W/C, aggregate ratios, adding admixtures like strength increasing agents, ASR inhibitor agents etc.

Keywords: waste glass, recycling, environmentally friendly, glass aggregate, strength development

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Authors: Minho Kwon, Jeonghee Lim, Yeongseok Jeong, Donghoon Shin, Kiyoung Kim

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Recently, global warming phenomenon has led to natural disasters caused by global environmental changes, and due to abnormal weather events, the frequency and intensity of heavy rain storm typhoons are increasing. Therefore, it is imperative to prepare for future heavy rain storms and typhoons. This study selects arbitrary target bridges and performs numerical analysis to evaluate the safety of bridge piers in the event that the water level changes. The numerical model is based on two-dimensional surface elements. Actual reinforced concrete was simulated by modeling concrete to include reinforcements, and a contact boundary model was applied between the ground and the concrete. The water level applied to the piers was considered at 18 levels between 7.5 m and 16.1 m. The elastic modulus, compressive strength, tensile strength, and yield strength of the reinforced concrete were calculated using 250 random combinations and numerical analysis was carried out for each water level. In the results of analysis, the bridge exceeded the stated limit at 15.0 m. At the maximum water level of 16.1m, the concrete’s failure rate was 35.2%, but the probability that the reinforcement would fail was 61.2%.

Keywords: Monte-Carlo method, pier, water level change, limit state

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Authors: Dorcas Ropo Abejide, Olamide Ahmed Falusi, Oladipupo Abdulazeez Yusuf Daudu, Bolaji Zuluqurineen Salihu, Muhammad Liman Muhammad

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This study evaluated the morpho-agronomic response of twenty-four (24) Nigerian Bambara groundnut landraces to water stress and genetic diversity of some selected accessions using SSR markers. The studies were carried out in the botanical garden of the Department of Plant Biology, Federal University of Technology, Minna, Niger State, Nigeria in a randomized complete block design using three replicates. Molecular analysis using SSR primers was carried out at the International Institute of Tropical Agriculture (IITA) Ibadan in order to characterize ten selected accessions comprising the seven most drought tolerant and three most susceptible accessions from the 24 accessions evaluated. Results revealed that water stress decreased morpho-agronomic traits such as plant height, leaf area, number of leaves per plant, seed yield, etc. A total of 22 alleles were detected by the SSR markers used with a mean number of 4 allelles. SSR markers MBamCO₃₃, Primer 65, and G358B2-D15 each detected 4 allelles, while Primer 3FR and 4FR detected 5 allelles each. The study revealed significantly high polymorphisms in 10 Loci. The mean value of polymorpic information content was 0.6997, implying the usefulness of the primers used in identifying genetic similarities and differences among the Bambara groundnut genotypes. The SSR analysis revealed a comparable pattern between genetic diversity and drought tolerance of the genotypes. The UPGMA dendrogram showed that at a genetic distance of 0.1, the accessions were grouped into three groups according to their level of tolerance to drought. The two most drought-tolerant accessions were grouped together, and the 5th and 6th most drought-tolerant accessions were also grouped together. This suggests that the genotypes grouped together may be genetically close, may possess similar genes, or have a common origin. The degree of genetic variants obtained from this profiling could be useful in Bambara groundnut breeding for drought tolerance. The identified drought tolerant Bambara groundnut landraces are important genetic resources for drought stress tolerance breeding programme of Bambara groundnut. The genotypes are also useful for germplasm conservation and global implications.

Keywords: Bambara groundnut, genetic diversity, germplasm, SSR markers, water stress

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Authors: Mohsen Amiri

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This study aimed at investigating the relationship between familial functioning, child characteristics, demographic variables and parenting stress and mental health among parents of children with mental disabilities. 200 parents (130 mothers and 70 fathers) were studied and they completed the Parenting Stress Index, General Health Questionnaire, Family Assessment Device and demographic questionnaires for parents and children. Data were analyzed using correlation and regression analysis. Regression analysis showed that child characteristics, familial functioning and parents demographic factors could predict 8, 4 and 17 percent of variance in parental stress and 3.6, 16 and 10 percent of variance in mental health, respectively. Familial functioning, child characteristics and parental demographic variables correlated with mental health and parental stress and could predict them.

Keywords: parenting stress, mental health, mentally disabled children, familial functioning, demographic variables

Procedia PDF Downloads 443

Authors: Shahram Baghban Cirus, Parisa Alizadeh Oskuie

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In a greenhouse experiment, green bean were inoculated with three levels of phosphorus (P1, P2, P3, respectively 0, 50, 100 kgP/h) and four levels of water stress(Fc1, Fc2, Fc3 ,Fc4, respectively 0.8Fc, 0.7Fc, 0.6Fc, 0.5Fc) and one species of VA mycorrhiza (Glomus versiform) or left uninocolated as control plants in the steril soil. AM colonization significantly stimulated plant growth, leaf area, shoot, and pod dry weight but water stress significantly decreased colonization, pod and shoot dry weight, and shoot P. The use P levels significantly increased leaf area, shoot, and pod dry weight, pods length, and colonization.

Keywords: green bean, plant growth, VA mycorrhiza, water-stress

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Authors: Ali Dalirbod, Peyman Ahmadian

Abstract:

Inclusions are unavoidable part of all steels. Non-metallic inclusions have significant effects on mechanical properties of steel. The effects of inclusion on stress concentration around the matrix/inclusion have been extensively studied. The results relating to single inclusion behavior, describe properly the behavior of stress but not the elongation drop. The raised stress in inclusion/matrix results in crack initiation. The influence of binary inclusions on stress concentration around matrix is a major aim of this work which is representative of the simple pattern distribution of non-metallic inclusions. Stress concentration around inclusions in this case depends on parameters like distance between two inclusions (d), angle between centrally linking line of two inclusions, load axis (φ), and rotational angle of inclusion (θ). FEM analysis was applied to investigate the highest and lowest ductility versus varying parameters above. The simulation results show that there is a critical distance between two cubic inclusions in which bigger than the threshold, the stress, and strain field in matrix/inclusions interface converts into individual fields around each inclusion.

Keywords: nitride inclusion, simulation, tensile properties, inclusion-matrix interface

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Authors: Vitoldas Vaitkevičius, Evaldas Šerelis

Abstract:

Silica fume, also known as microsilica (MS) or condensed silica fume is a by-product of the production of silicon metal or ferrosilicon alloys. Silica fume is one of the most effective pozzolanic additives which could be used for ultrahigh performance and other types of concrete. Despite the fact, however is not entirely clear, which amount of silica fume is most optimal for UHPC. Main objective of this experiment was to find optimal amount of silica fume for UHPC with and without thermal treatment, when different amount of quartz powder is substituted by silica fume. In this work were investigated four different composition of UHPC with different amount of silica fume. Silica fume were added 0, 10, 15 and 20% of cement (by weight) to UHPC mixture. Optimal amount of silica fume was determined by slump, viscosity, qualitative and quantitative XRD analysis and compression strength tests methods.

Keywords: compressive strength, silica fume, ultrahigh performance concrete, XRD

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Authors: Binyamien Rasoul

Abstract:

Portland cement is one of the most widely used construction materials in the world today; however, manufacture of ordinary Portland cement (OPC) emission significant amount of CO2 resulting environmental impact. On the other hand, rice husk ash (RHA), which is produce as by product material is generally considered to be an environmental issue as a waste material. This material (RHA) consists of non-crystalline silicon dioxide with high specific surface area and high pozzolanic reactivity. These RHA properties can demonstrate a significant influence in improving the mechanical and durability properties of mortar and concrete. Furthermore, rice husk ash can provide a cost effective and give concrete more sustainability. In this paper, chemical composition, reactive silica and fineness effect was assessed by examining five different types of RHA. Mortars and concrete specimens were molded with 5% to 50% of ash, replacing the Portland cement, and measured their compressive and tensile strength behavior. Beyond it, another two parameters had been considered: the durability of concrete blended RHA, and effect of temperature on the transformed of amorphous structure to crystalline form. To obtain the rice husk ash properties, these different types were subjected to X-Ray fluorescence to determine the chemical composition, while pozzolanic activity obtained by using X-Ray diffraction test. On the other hand, finesses and specific surface area were obtained by used Malvern Mastersizer 2000 test. The measured parameters properties of fresh mortar and concrete obtained by used flow table and slump test. While, for hardened mortar and concrete the compressive and tensile strength determined pulse the chloride ions penetration for concrete using NT Build 492 (Nord Test) – non-steady state migration test (RMT Test). The obtained test results indicated that RHA can be used as a cement replacement material in concrete with considerable proportion up to 50% percentages without compromising concrete strength. The use of RHA in the concrete as blending materials improved the different characteristics of the concrete product. The paper concludes that to exhibits a good compressive strength of OPC mortar or concrete with increase RHA replacement ratio rice husk ash should be consist of high silica content with high pozzolanic activity. Furthermore, with high amount of carbon content (12%) could be improve the strength of concrete when the silica structure is totally amorphous. As well RHA with high amount of crystalline form (25%) can be used as cement replacement when the silica content over 90%. The workability and strength of concrete increased by used of superplasticizer and it depends on the silica structure and carbon content. This study therefore is an investigation of the effect of partially replacing Ordinary Portland cement (OPC) with Rice hush Ash (RHA) on the mechanical properties and durability of concrete. This paper gives satisfactory results to use RHA in sustainable construction in order to reduce the carbon footprint associated with cement industry.

Keywords: OPC, ordinary Portland cement, RHA rice husk ash, W/B water to binder ratio, CO2, carbon dioxide

Procedia PDF Downloads 189

Authors: Gaurav Bansod, Swapnil Sutar, Abhijit Patil, Jagdish Patil

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This paper proposes an ultra-lightweight cipher NUX. NUX is a generalized Feistel network. It supports 128/80 bit key length and block length of 64 bit. For 128 bit key length, NUX needs only 1022 GEs which is less as compared to all existing cipher design. NUX design results into less footprint area and minimal memory size. This paper presents security analysis of NUX cipher design which shows cipher’s resistance against basic attacks like Linear and Differential Cryptanalysis. Advanced attacks like Biclique attack is also mounted on NUX cipher design. Two different F function in NUX cipher design results in high diffusion mechanism which generates large number of active S-boxes in minimum number of rounds. NUX cipher has total 31 rounds. NUX design will be best-suited design for critical application like smart grid, IoT, wireless sensor network, where memory size, footprint area and the power dissipation are the major constraints.

Keywords: lightweight cryptography, Feistel cipher, block cipher, IoT, encryption, embedded security, ubiquitous computing

Procedia PDF Downloads 358

Authors: Bhaumik Merchant, Ajay Gelot

Abstract:

Concrete is good in compression but if any type of strain applied to it, it starts to fail. Where the steel is good tension, it can bear the deflection up to its elastic limits. This project is based on behavior of engineered cementitious composited (ECC) when it is replaced with the different amount of Polyvinyl Alcohol (PVA) Fibers. As for research, PVA fibers is used with cementitious up to 2% to evaluate the optimum amount of fiber on which we can find the maximum compressive, tensile and flexural strength. PVA is basically an adhesive which is used to formulate glue. Generally due to excessive loading, cracks develops which concludes to successive damage to the structural component. In research plasticizer is used to increase workability. With the help of optimum amount of PVA fibers, it can limit the crack widths up to 60µm to 100µm. Also can be used to reduce resources and funds for rehabilitation of structure. At the starting this fiber concrete can be double the cost as compare to conventional concrete but as it can amplify the duration of structure, it will be less costlier than the conventional concrete.

Keywords: compressive strength, engineered cementitious composites, flexural strength, polyvinyl alcohol fibers, rehabilitation of structures

Procedia PDF Downloads 285