Search results for: abiotic stresses

Authors: Eugene Ivanov, Eduardo del-Rio, Igor Kapchenko, Maija Nystrӧm, Juha Kotila

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Series of low modulus beta Ti alloy billets and powders can be produced in commercial quantities using a combination of electron beam melting (EBM) and EIGA atomization processes. In the present study, TNZT alloy powder was produced and processed in the EOSINT M290 laser sintering system to produce parts for mechanical testing. Post heat treatments such as diffusion annealing to reduce internal stresses or hot isostatic pressing to remove closed pores were not applied. The density can visually be estimated to be > 99,9 %. According to EDS study Nb, Zr, and Ta are distributed homogeneously throughout the printed sample. There are no indications for any segregation or chemical inhomogeneity, i.e. variation of the element distribution. These points to the fact that under the applied experimental conditions the melt generated by the laser rapidly cools down in the SLM (Selective Laser Melting) process. The selective laser sintering yielded dense structures with relatively good surface quality. The mechanical properties, especially the elongation (24%) along with tensile strength ( > 500MPa) and modulus of elasticity (~60GPa), were found to be promising compared to titanium alloys in general.

Keywords: beta titanium alloys, additive manufacturing, powder, implants

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Authors: Emma Serwaa Obobisa, Winifred Essaah

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Significant worldwide trends including urbanization, industrialization, globalization, and the impending digitization have all contributed to human prosperity. However, the majority of these advancements fail to take sustainability into account, which caused the earth to manifest its retaliation in many forms. Since the world is already well-advanced, mankind needs a mature development that instills sustainability in its acts. As a result, the United Nations established the Sustainable Development Goals (SDGs), which set forth guidelines for human behavior to ensure that the ecosystem and mankind coexist as a unified, autonomous system. The study investigates the role of eco-innovation, renewable energy consumption, human capital, environmental tax, and natural resources in achieving European Union countries' sustainable development goals. The results show that eco-innovation, renewable energy consumption, human capital, and environmental tax have a negative relationship with consumption-based CO₂ emissions but a positive relationship with natural resources. These findings suggest that governments in European Union countries commit to encouraging environmentally friendly technology advances and green investment. It also stresses the need to enforce regulations that regulate the activities of polluting firms in the region with strictness.

Keywords: sustainable development, Eco-innovation, renewable energy, CO₂ emissions

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Authors: Amritha Nair, Fleur Visser, Ian Maddock, Jonas Schoelynck

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Inland waters such as streams sustain a rich variety of species and are essentially hotspots for biodiversity. Submerged aquatic vegetation, also known as SAV, forms an important part of ecologically healthy river systems. Direct and indirect human influences, such as climate change are putting stress on aquatic plant communities, ranging from the invasion of non-native species and grazing, to changes in the river flow conditions and temperature. There is a need to monitor SAV, because they are in a state of deterioration and their disappearance will greatly impact river ecosystems. Like terrestrial plants, SAV can show visible signs of stress. However, the techniques used to map terrestrial vegetation from its spectral reflectance, are not easily transferable to a submerged environment. Optical remote sensing techniques are employed to detect the stress from remotely sensed images through multispectral imagery and Structure from Motion photogrammetry. The effect of the overlying water column in the form of refraction, attenuation of visible and near infrared bands in water, as well as highly moving targets, are NIR) key challenges that arise when remotely mapping SAV. This study looks into the possibility of mapping the changes in spectral signatures from SAV and their response to certain stresses.

Keywords: submerged aquatic vegetation, structure from motion, photogrammetry, multispectral, spectroscopy

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Authors: Yu Chen

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This paper investigates the influence of flaw on failure process of rock-like material under uniaxial compression. In laboratory, the uniaxial compression tests of intact specimens and a series of specimens within single flaw were conducted. The inclination angle of flaws includes 0°, 15°, 30°, 45°, 60°, 75° and 90°. Based on the laboratory tests, the corresponding models of numerical simulation were built and loaded in PFC2D. After analysing the crack initiation and failure modes, deformation field, and energy mechanism for both laboratory tests and numerical simulation, it can be concluded that the influence of flaws on the failure process is determined by its inclination. The characteristic stresses increase as flaw angle rising basically. The tensile cracks develop from gentle flaws (α ≤ 30°) and the shear cracks develop from other flaws. The propagation of cracks changes during failure process and the failure mode of a specimen corresponds to the orientation of the flaw. A flaw has significant influence on the transverse deformation field at the middle of the specimen, except the 75° and 90° flaw sample. The input energy, strain energy and dissipation energy of specimens show approximate increase trends with flaw angle rising and it presents large difference on the energy distribution.

Keywords: failure pattern, particle deformation field, energy mechanism, PFC

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Authors: Alireza Taghdiri, Sara Ghanbarzade Ghomi

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With gravity load reduction in the structural and non-structural components, the lightweight construction will be achieved as well as the improvement of efficiency and functional specifications. The advantages of lightweight construction can be examined in two levels. The first is the mass reduction of load bearing structure which results in increasing internal useful space and the other one is the mass reduction of building which decreases the effects of seismic load as a result. In order to achieve this goal, the essential building materials specifications and also optimum load bearing geometry of structural systems and elements have to be considered, so lightweight materials selection particularly with lightweight aggregate for building components will be the first step of lightweight construction. In the next step, in addition to selecting the prominent samples of Iran's traditional architecture, the process of these works improvement is analyzed through the viewpoints of structural efficiency and lightweighting and also the practical methods of lightweight construction have been extracted. The optimum design of load bearing geometry of structural system has to be considered not only in the structural system elements, but also in their composition and the selection of dimensions, proportions, forms and optimum orientations, can lead to get a maximum materials efficiency for loads and stresses bearing.

Keywords: gravity load, lightweighting structural system, load bearing geometry, seismic behavior

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Authors: Ahmad El Hajjar, Joanna Eid, Salima Bouchemella, Tariq Ouahbi, Benoit Duchemin, Said Taibi

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In our present society, raw earth presents an alternative as an energy-saving building material for dealing with climate and environmental issues. Nevertheless, it has a sensitivity to water, due to the presence of fines, which has a direct effect on its consistency. This can be expressed during desiccation, by shrinkage deformations resulting in cracking that begins once the internal tensile stresses developed, due to suction, exceed the tensile strength of the material. This work deals with the evolution of the strain of clay samples, from the beginning of shrinkage until the initiation of crack, using the DIC (Digital Image Correlation) technique. In order to understand the origin of cracking, desiccation is studied for different boundary conditions and depending on the intrinsic characteristics of the material. On the other hand, a study of restrained shrinkage is carried out on the ring test to investigate the ultimate tensile strength from which the crack begins in the dough of clay. The purpose of this test is to find the type of reinforcement adapted to thwart in the cracking of the material. A microscopic analysis of the damaged area is necessary to link the macroscopic mechanisms of cracking to the various physicochemical phenomena at the microscopic scale in order to understand the different microstructural mechanisms and their impact on the macroscopic shrinkage.

Keywords: clayey soil, shrinkage, strain, cracking, digital image correlation

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Authors: Chao He, Shunhua Zhou, Peijun Guo

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The vast majority of existing underground railway lines consist of twin tunnels. In this paper, the dynamic interaction between two neighboring tunnels in a layered half-space is investigated by an analytical model. The two tunnels are modelled as cylindrical thin shells, while the soil in the form of a layered half-space with two cylindrical cavities is simulated by the elastic continuum theory. The transfer matrix method is first used to derive the relationship between the plane wave vectors in arbitrary layers and the source layer. Thereafter, the wave translation and transformation are introduced to determine the plane and cylindrical wave vectors in the source layer. The solution for the dynamic interaction between twin tunnels in a layered half-space is obtained by means of the compatibility of displacements and equilibrium of stresses on the two tunnel–soil interfaces. By coupling the proposed model with a fully track model, the train-induced vibrations from twin tunnels in a multi-layered half-space are investigated. The numerical results demonstrate that the existence of a neighboring tunnel has a significant effect on ground vibrations.

Keywords: underground railway, twin tunnels, wave translation and transformation, transfer matrix method

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Authors: Moustafa Osman Mohammed

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Integration sustainability outcomes give attention to construction ecology in the design review of urban environments to comply with Earth’s System that is composed of integral parts of the (i.e., physical, chemical and biological components). Naturally, exchange patterns of industrial ecology have consistent and periodic cycles to preserve energy flows and materials in Earth’s System. When engineering topology is affecting internal and external processes in system networks, it postulated the valence of the first-level spatial outcome (i.e., project compatibility success). These instrumentalities are dependent on relating the second-level outcome (i.e., participant security satisfaction). Construction ecology approach feedback energy from resources flows between biotic and abiotic in the entire Earth’s ecosystems. These spatial outcomes are providing an innovation, as entails a wide range of interactions to state, regulate and feedback “topology” to flow as “interdisciplinary equilibrium” of ecosystems. The interrelation dynamics of ecosystems are performing a process in a certain location within an appropriate time for characterizing their unique structure in “equilibrium patterns”, such as biosphere and collecting a composite structure of many distributed feedback flows. These interdisciplinary systems regulate their dynamics within complex structures. These dynamic mechanisms of the ecosystem regulate physical and chemical properties to enable a gradual and prolonged incremental pattern to develop a stable structure. The engineering topology of construction ecology for integration sustainability outcomes offers an interesting tool for ecologists and engineers in the simulation paradigm as an initial form of development structure within compatible computer software. This approach argues from ecology, resource savings, static load design, financial other pragmatic reasons, while an artistic/architectural perspective, these are not decisive. The paper described an attempt to unify analytic and analogical spatial modeling in developing urban environments as a relational setting, using optimization software and applied as an example of integrated industrial ecology where the construction process is based on a topology optimization approach.

Keywords: construction ecology, industrial ecology, urban topology, environmental planning

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Authors: Adil Balla Elkrail

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Visual MODFLOW computer codes were selected to simulate head distribution, calculate the groundwater budgets of the area, and evaluate the effect of external stresses on the groundwater head and to demonstrate how the groundwater model can be used as a comparative technique in order to optimize utilization of the groundwater resource. A conceptual model of the study area, aquifer parameters, boundary, and initial conditions were used to simulate the flow model. The trial-and-error technique was used to calibrate the model. The most important criteria used to check the calibrated model were Root Mean Square error (RMS), Mean Absolute error (AM), Normalized Root Mean Square error (NRMS) and mass balance. The maps of the simulated heads elaborated acceptable model calibration compared to observed heads map. A time length of eight years and the observed heads of the year 2004 were used for model prediction. The predictive simulation showed that the continuation of pumping will cause relatively high changes in head distribution and components of groundwater budget whereas, the low deficit computed (7122 m3/d) between inflows and outflows cannot create a significant drawdown of the potentiometric level. Hence, the area under consideration may represent a high permeability and productive zone and strongly recommended for further groundwater development.

Keywords: aquifers, model simulation, groundwater, calibrations, trail-and- error, prediction

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Authors: Carolina S. Monteiro, Eugénia Pinto, Miguel A. Faria, Sara C. Cunha

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Rice (Oryza sativa) production plays a vital role in reducing hunger and poverty and assumes particular importance in low-income and developing countries. Rice is a sensitive plant, and production occurs strictly where suitable temperature and water conditions are found. Climatic changes are likely to affect worldwide, and some models have predicted increased temperatures, variations in atmospheric CO₂ concentrations and modification in precipitation patterns. Therefore, the ongoing climatic changes threaten rice production by increasing biotic and abiotic stress factors, and crops will grow in different environmental conditions in the following years. Around the world, the effects will be regional and can be detrimental or advantageous depending on the region. Mediterranean zones have been identified as possible hot spots, where dramatic temperature changes, modifications of CO₂ levels, and rainfall patterns are predicted. The actual estimated atmospheric CO₂ concentration is around 400 ppm, and it is predicted that it can reach up to 1000–1200 ppm, which can lead to a temperature increase of 2–4 °C. Alongside, rainfall patterns are also expected to change, with more extreme wet/dry episodes taking place. As a result, it could increase the migration of pathogens, and a shift in the occurrence of mycotoxins, concerning their types and concentrations, is expected. Mycotoxigenic spoilage fungi can colonize the crops and be present in all rice food chain supplies, especially Penicillium species, mainly resulting in ochratoxin A (OTA) contamination. In this scenario, the objectives of the present study are evaluating the effect of temperature (20 vs. 25 °C), CO₂ (400 vs. 1000 ppm), and water stress (0.93 vs 0.95 water activity) on growth and OTA production by a Penicillium nordicum strain in vitro on rice-based media and when colonizing layers of raw rice. Results demonstrate the effect of temperature, CO₂ and drought on the OTA production in a rice-based environment, thus contributing to the development of mycotoxins predictive models in climate change scenarios. As a result, improving mycotoxins' surveillance and monitoring systems, whose occurrence can be more frequent due to climatic changes, seems relevant and necessary. The development of prediction models for hazard contaminants presents in foods highly sensitive to climatic changes, such as mycotoxins, in the highly probable new agricultural scenarios is of paramount importance.

Keywords: climate changes, ochratoxin A, penicillium, rice

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Authors: Jacques M. Berner, Monja Gerber, Gillian L. Maggs-Kolling, Stuart J. Piketh

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The enigmatic melon species, Acanthosicyos horridus Welw. ex Hook. f., locally known as !nara, is endemic to the hyper-arid Namib Desert, where it thrives in sandy dune areas and dry river banks. The Namib Desert is characterized by extreme weather conditions which include high temperatures, very low rainfall, and extremely dry air. Plant and animals that have made the Namib Dessert their home are dependent on non-rainfall water inputs, like fog, dew and water vapor, for survival. Fog is believed to be the most important non-rainfall water input for most of the coastal Namib Desert and is a life line to many Namib plants and animals. It is commonly assumed that the !nara plant is adapted and dependent upon coastal fog events. The !nara plant shares many comparable adaptive features with other organisms that are known to exploit fog as a source of moisture. These include groove-like structures on the stems and the cone-like structures of thorns. These structures are believed to be the driving forces behind directional water flow that allow plants to take advantage of fog events. The !nara-fog interaction was investigated in this study to determine the dependence of !nara on these fog events, as it would illustrate strategies to benefit from non-rainfall water inputs. The direct water uptake capacity of !nara shoots was investigated through absorption tests. Furthermore, the movement and behavior of fluorescent water droplets on a !nara stem were investigated through time-lapse macrophotography. The shoot water potential was measured to investigate the effect of fog on the water status of !nara stems. These tests were used to determine whether the morphology of !nara has evolved to exploit fog as a non-rainfall water input and whether the !nara plant has adapted physiologically in response to fog. Chlorophyll a fluorescence was used to compare the photochemical efficiency of !nara plants on days with fog events to that on non-foggy days. The results indicate that !nara plants do have the ability to take advantage of fog events as commonly believed. However, the !nara plant did not exhibit visible signs of drought stress and this, together with the strong shoot water potential, indicates that these plants are reliant on permanent underground water sources. Chlorophyll a fluorescence data indicated that temperature stress and wind were some of the main abiotic factors influencing the plants’ overall vitality.

Keywords: Acanthosicyos horridus, chlorophyll a fluorescence, fog, foliar absorption, !nara

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Authors: Hong Li, Tingxian Li, Xudong Wang, Qinghuo Lin

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Excess-iron (Fe) stresses involved in legume symbiotic nitrogen fixation are not understood. Our objectives were to investigate the tolerance of yardlong-bean plants to soil excess-Fe stress and antagonistic effects of organic amendments and rhizobial inoculants on plant root nodulation and stem ureide formation. The study was conducted in the tropical Hainan Island during 2012-2013. The soil was strongly acidic (pH 5.3±0.4) and highly variable in Fe concentrations(596±79 mg/kg). The treatments were arranged in a split-plot design with three blocks. The treatment effects were significant on root nodulation, stem ureide, amino acids, plant N/Fe accumulation and bean yields (P<0.05). The yardlong-bean stem allantoin, amino acids and nitrate concentrations and relative ureide % declined with high soil Fe concentrations (>300 mg/kg). It was concluded that the co-variance of excess Fe stress could inhibit legume symbiotic N fixation efficiency. Organic amendments and rhizobial inoculants could help improve crop tolerance to excess Fe stress.

Keywords: atmospheric N fixation, root nodulation, soil Fe co-variance, stem ureide, yardlong-bean plants

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Authors: Djamel Ouzandja, Boualem Tiliouine

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The safety evaluation of the concrete gravity dams subjected to seismic excitations is really very complex as the earthquake response of the concrete gravity dam depends upon its contraction joints with foundation soil. This paper presents the seismic response of concrete gravity dams considering friction contact and welded contact. Friction contact is provided using contact elements. Two-dimensional (2D) finite element model of Oued Fodda concrete gravity dam, located in Chlef at the west of Algeria, is used for this purpose. Linear and nonlinear analyses considering dam-foundation soil interaction are performed using ANSYS software. The reservoir water is modeled as added mass using the Westergaard approach. The Drucker-Prager model is preferred for dam and foundation rock in nonlinear analyses. The surface-to-surface contact elements based on the Coulomb's friction law are used to describe the friction. These contact elements use a target surface and a contact surface to form a contact pair. According to this study, the seismic analysis of concrete gravity dams including base sliding. When the friction contact is considered in joints, the base sliding displacement occurs along the dam-foundation soil contact interface. Besides, the base sliding may generally decrease the principal stresses in the dam.

Keywords: concrete gravity dam, dynamic soil-structure interaction, friction contact, sliding

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Authors: Amir R. Askari, Masoud Tahani

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The objective of the present paper is to investigate the effect of size on the vibrational behavior of fully clamped rectangular micro-plates based on the modified couple stress theory (MCST). To this end, a size-dependent Kirchhoff plate model is considered and the equation of motion which accounts for the effect of residual and couple stress components is derived using the Hamilton's principle. The eigenvalue problem associated with the free vibrations of fully clamped micro-plates is extracted and solved analytically using the extended Kantorovich method (EKM). The present findings are compared and validated by available results in the literature and an excellent agreement between them is observed. A parametric study is also conducted to show the significant effects of couple stress components on natural frequencies of fully clamped micro-plates. It is found that the ratio of MCST natural frequencies to those obtained by the classical theory (CT) only depends on the Poisson's ratio of the plate and is totally independent of plate's aspect ratio for cases with no residual stresses.

Keywords: vibrational analysis, modified couple stress theory, fully clamped rectangular micro-plates, extended Kantorovich method.

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Authors: Masoud Mahdavi

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The structure is made using different members and combining them with each other. These members are basically based on technical and engineering principles and are combined in different ways and have their own unique effects on the building. Trusses are one of the most common and important members of the structure, accounting for a large percentage of the power transmission structure in the building. Different types of trusses are based on structural needs and evaluating and making complete comparisons between them is one of the most important engineering analyses. In the present study, four types of trusses have been studied; 1) Hawe truss, 2) Pratt truss, 3) k truss, and 4) warren truss, under cyclic loading for 80 seconds. The trusses are modeled in 3d using st₃₇ steel. The results showed that Hawe trusses had higher values ​​than all other trusses (k, Pratt and Warren) in all the studied indicators. Indicators examined in the study include; 1) von Mises stresses, 2) displacement, 3) support force, 4) velocity, 5) acceleration, 6) capacity (hysteresis curve) and 7) energy diagram. Pratt truss in indicators; Mises stress, displacement, energy have the least amount compared to other trusses. K truss in indicators; support force, speed and acceleration are the lowest compared to other trusses.

Keywords: hawe truss, pratt truss, K truss, warren truss, cyclic loading, finite element method

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Authors: Eman M. Eissa, Hany M. Hasanin, Mahmoud Abd-Elhamid, S. M. Muyeen, T. Fernando, H. H. C. Iu

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Among all available wind energy conversion systems (WECS), the direct driven permanent magnet synchronous generator integrated with power electronic interfaces is becoming popular due to its capability of extracting optimal energy capture, reduced mechanical stresses, no need to external excitation current, meaning less losses, and more compact size. Simple structure, low maintenance cost; and its decoupling control performance is much less sensitive to the parameter variations of the generator. This paper attempts to present a review of the control and optimization strategies of WECS based on permanent magnet synchronous generator (PMSG) and overview the most recent research trends in this field. The main aims of this review include; the generalized overall WECS starting from turbines, generators, and control strategies including converters, maximum power point tracking (MPPT), ending with DC-link control. The optimization methods of the controller parameters necessary to guarantee the operation of the system efficiently and safely, especially when connected to the power grid are also presented.

Keywords: control and optimization techniques, permanent magnet synchronous generator, variable speed wind turbines, wind energy conversion system

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Authors: Olumide A. Fafore, Khondlo Mtshali

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The beginning of the 21st century saw the emergence of new and global threats to national and transnational security in West Africa and the Asia Pacific regions as a result of the spread of jihadist terrorism across borders, a manifestation of the rise of radical Islam. Extremist and armed Islamic movements influenced by Salafism, the Jihad in Afghanistan and the Muslim Brotherhood are prevalent in Northern Nigeria, Niger, Cameroon, Mali, Chad, Pakistan, Afghanistan, and India. Carrying out attacks across borders, including assassinations, murders, armed robberies, and kidnapping, assisted by open and porous borders and large flow of illegal immigrants across borders. This paper examines the effect of Radical Islam on Transnational security through a review of past literature and the social and security consequences on the people of the regions. Our findings indicate that the activities of armed Islamic movements such as Boko Haram, Ansaru and Al-Qaeda are having a negative impact on the economy, development, and security of the states and people of West Africa and the Asia Pacific. It stresses the importance of regional, transnational and international cooperation, as these threats to national and transnational security can no longer be solved in a national or regional framework.

Keywords: Islamic movements, jihadist terrorism, radical Islam, transnational security

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Authors: Chenyu Huang, Minrong Cui, Hua Fang, Luqing Zhang, Yunlong Yu

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The emergence and spread of antibiotic resistance genes (ARGs) have become a pressing issue in global agricultural production. However, understanding how these ARGs spread across different spatial scales, especially when exposed to both pesticides and antibiotics, has remained a challenge. Here, metagenomic assembly and binning methodologies were used to determine the mechanism of ARG propagation within soil-lettuce systems exposed to both fungicides and antibiotics. The results of our study showed that the presence of fungicide and antibiotic stresses had a significant impact on certain bacterial communities. Notably, we observed that ARGs were primarily transferred from the soil to the plant through plasmids. The selective pressure exerted by fungicides and antibiotics contributed to an increase in unique ARGs present on lettuce leaves. Moreover, ARGs located on chromosomes and plasmids followed different transmission patterns. The presence of diverse selective pressures, a result of compound treatments involving antibiotics and fungicides, amplifies this phenomenon. Consequently, there is a higher probability of bacteria developing multi-antibiotic resistance under the combined pressure of fungicides and antibiotics. In summary, our findings highlight that combined fungicide and antibiotic treatments are more likely to drive the acquisition of ARGs within the soil-plant system and may increase the risk of human ingestion.

Keywords: soil-lettuce system, fungicide, antibiotic, ARG, transmission

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Authors: Amin Kamal Akhnoukh, Lois Zaki Kamel, Magued Mourad Barsoum

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The objective of this research is to mitigate and prevent the alkali silica reactivity (ASR) in highway construction projects. ASR is a deleterious reaction initiated when the silica content of the aggregate reacts with alkali hydroxides in cement in the presence of relatively high moisture content. The ASR results in the formation of an expansive white colored gel-like material which forms the destructive tensile stresses inside hardened concrete. In this research, different types of local aggregates available in the State of Arkansas were mixed and mortar bars were poured according to the ASTM specifications. Mortar bars expansion was measured versus time and aggregates with potential ASR problems were detected. Different types of supplementary cementitious materials (SCMs) were used in remixing mortar bars with highly reactive aggregates. Length changes for remixed bars proved that different types of SCMs can be successfully used in reducing the expansive effect of ASR. SCMs percentage by weight is highly dependent on the SCM type. The result of this study will help avoiding future losses due to ASR cracking in construction project and reduce the maintenance, repair, and replacement budgets required for highways network.

Keywords: alkali silica reaction, aggregates, misture, cracks, Mortar Bar Test, supplementary cementitious materials

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Authors: Hana Gebremariam Liliso

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This study investigates the factors contributing to the deterioration of thick asphalt pavements, such as rutting and cracking. We focus on the combined influence of traffic loads and pavement structure. This study uses a three-dimensional finite element model with a Mohr-Coulomb failure criterion to analyze the stress levels near the pavement's surface under realistic conditions. Our model considers various factors, including tire-pavement contact stresses, asphalt properties, moving loads, and dynamic analysis. This research suggests that cracking tends to occur between dual tires. Some key discoveries include the risk of cracking increases as temperatures rise; surface cracking at high temperatures is associated with distortional deformation; using a uniform contact stress distribution underestimates the risk of failure compared to realistic three-dimensional tire contact stress, particularly at high temperatures; the risk of failure is higher near the surface when there is a negative temperature gradient in the asphalt layer; and debonding beneath the surface layer leads to increased shear stress and premature failure around the interface.

Keywords: asphalt pavement, surface failure, 3d finite element model, multiaxial stress states, Mohr-Coulomb failure criterion

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Authors: Khiaira S. Hassan, Abbas S. Alwan, Muna K. Abbass

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This research aims to study the effect of the liquid nitriding and shot peening on the hardness, surface roughness, residual stress, microstructure and corrosion behavior of austenite stainless steel 316 L. Chemical surface heat treatment by liquid nitriding process was carried out at 500 °C for 1 h and followed by shot peening with using ball steel diameter of 1.25 mm in different exposure time of 10 and 20 min. Electrochemical corrosion test was applied in sea water (3.5% NaCl solution) by using potentostat instrument. The results showed that the nitride layer consists of a compound layer (white layer) and diffusion zone immediately below the alloy layer. It has been found that the mechanical treatment (shot peening) has led to the formation of compressive residual stresses in layer surface that increased the hardness of stainless steel surface. All surface treatment (nitriding and shot peening) processes have led to the formation of carbide of CrN in hard surface layer. It was shown that both processes caused an increase in surface hardness and roughness which increases with shot peening time. Also, the corrosion results showed that the liquid nitriding and shot peening processes increase the corrosion rate to values more than that of not treated stainless steel.

Keywords: stainless steel 316L, shot peening, nitriding, corrosion, hardness

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Authors: Sabiha Shahid Antora, Young Ki Chang

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Along with various farm management technologies, imagery is an important tool that facilitates crop assessment, monitoring, and management. As a consequence, drone imaging technology is playing a vital role to capture the state of the entire field for yield mapping, crop scouting, weed detection, and so on. Although it is essential to inspect the cultivable lands in real-time for making rapid decisions regarding field variable inputs to combat stresses and diseases, drone imagery is still evolving in this area of interest. Cost margin and post-processing complexions of the image stream are the main challenges of imaging technology. Therefore, this proposed project involves the cost-effective field programmable gate array (FPGA) based image processing device that would process the image stream in real-time as well as providing the processed output to support on-the-spot decisions in the crop field. As a result, the real-time FPGA-based image processing system would reduce operating costs while minimizing a few intermediate steps to deliver scalable field decisions.

Keywords: real-time, FPGA, drone imagery, image processing, crop monitoring

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Authors: Mario Gómez, Won Ho Kim, Ángel Licona, José Carlos Rodríguez

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This article analyzes innovation activity in Mexico and South Korea. It develops an econometric model to test for structural breaks in the number of patent applications filed by residents and nonresidents in these countries during the period of 1965 to 2012. These changes may suggest that firms’ innovative capabilities have changed because of implementing different science, technology and innovation (STI) policies in Mexico and South Korea. Two important features characterize this research from others already developed by these authors. First, the theoretical research framework in this research is the debate between the assimilation view of growth and the accumulation view of growth. This characteristic suggests that trade liberalization should be accompanied by an adequate STI policy to boost competitiveness among indigenous firms. Second, the analysis in this research stresses the importance of key actors (e.g. governments) to successfully develop innovation capabilities among indigenous firms. Therefore, the question conducting this research is how STI policies in Mexico and South Korea contributed to develop firms’ innovation capabilities in these countries during last decades? The results from this research suggests that STI policy in South Korea was more suitable to boost innovation firms to compete in markets. Data to develop this research was released by the World Intellectual Property Organization (WIPO).

Keywords: innovation, Mexico, South Korea, science, technology and innovation policy

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Authors: Asif Hasan

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Among the reported suitable mariculture species in Bangladesh, seabass and mullet are the two most popular candidates due to their high market values. Several field studies conducted on the culture of seabass in Bangladesh, it still remains a challenge to commercially grow this species due to its exclusive carnivorous nature. In contrast, the grey mullet (M. cephalus) is a fast-growing, omnivorous euryhaline fish that has shown excellent growth in many areas including South Asia. Choice of a sustainable aquaculture technique must consider the productivity and yield as well as their environmental suitability. This study was designed to elucidate the ecologically suitable culture technique of M. cephalus in brakishwater ponds by comparing the biotic and abiotic components of pond ecosystem. In addition to growth parameters (yield, ADG, SGR, weight gain, FCR), Physicochemical parameters (Temperature, DO, pH, salinity, TDS, transparency, ammonia, and Chlorophyll-a concentration) and biological community composition (phytoplankton, zooplankton and benthic macroinvertebrates) were investigated from ponds under Semi-intensive, Improve extensive and Traditional culture system. While temperature were similar in the three culture types, ponds under improve-extensive showed better environmental conditions with significantly higher mean DO and transparency, and lower TDS and Chlorophyll-a. The abundance of zooplankton, phytoplankton and benthic macroinvertebrates were apparently higher in semi-intensive ponds. The Analysis of Similarity (ANOSIM) suggested moderate difference in the planktonic community composition. While the fish growth parameters of M. cephalus and total yield did not differ significantly between three systems, M. cephalus yield (kg/decimal) was apparently higher in semi-intensive pond due to high stocking density and intensive feeding. The results suggested that the difference between the three systems were due to more efficient utilization of nutrients in improve extensive ponds which affected fish growth through trophic cascades. This study suggested that different culture system of M. cephalus is an alternative and more beneficial method owing to its ecological and economic benefits in brackishwater ponds.

Keywords: Mugil cephalus, pond ecosystem, mariculture, fisheries management

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Authors: Moustafa Osman Mohammed

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Construction industry, as one of the main contributor in depletion of natural resources, influences climate change. This paper discusses incremental and evolutionary development of the proposed models for optimization of a life-cycle analysis to explicit strategy for evaluation systems. The main categories are virtually irresistible for introducing uncertainties, uptake composite structure model (CSM) as environmental management systems (EMSs) in a practice science of evaluation small and medium-sized enterprises (SMEs). The model simplified complex systems to reflect nature systems’ input, output and outcomes mode influence “framework measures” and give a maximum likelihood estimation of how elements are simulated over the composite structure. The traditional knowledge of modeling is based on physical dynamic and static patterns regarding parameters influence environment. It unified methods to demonstrate how construction systems ecology interrelated from management prospective in procedure reflects the effect of the effects of engineering systems to ecology as ultimately unified technologies in extensive range beyond constructions impact so as, - energy systems. Sustainability broadens socioeconomic parameters to practice science that meets recovery performance, engineering reflects the generic control of protective systems. When the environmental model employed properly, management decision process in governments or corporations could address policy for accomplishment strategic plans precisely. The management and engineering limitation focuses on autocatalytic control as a close cellular system to naturally balance anthropogenic insertions or aggregation structure systems to pound equilibrium as steady stable conditions. Thereby, construction systems ecology incorporates engineering and management scheme, as a midpoint stage between biotic and abiotic components to predict constructions impact. The later outcomes’ theory of environmental obligation suggests either a procedures of method or technique that is achieved in sustainability impact of construction system ecology (SICSE), as a relative mitigation measure of deviation control, ultimately.

Keywords: sustainability, environmental impact assessment, environemtal management, construction ecology

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Authors: Mohammed A. Sakr, Tarek M. Khalifa, Walid N. Mansour

Abstract:

External bonding of fiber reinforced polymer (FRP) plates to reinforced concrete (RC) beams is an effective technique for flexural strengthening. This paper presents an analytical parametric study on the behavior of RC continuous beams flexurally strengthened with externally bonded FRP plates on the upper and lower fibers, conducted using simple uniaxial nonlinear finite element model (UNFEM). UNFEM is able to estimate the load-carrying capacity, different failure modes and the interfacial stresses of RC continuous beams flexurally strengthened with externally bonded FRP plates on the upper and lower fibers. The study investigated the effect of five key parameters on the behavior and moment redistribution of FRP-reinforced continuous beams. The investigated parameters were the length of the FRP plate, the width and the thickness of the FRP plate, the ratio between the area of the FRP plate to the concrete area, the cohesive shear strength of the adhesive layer, and the concrete compressive strength. The investigation resulted in a number of important conclusions reflecting the effects of the studied parameters on the behavior of RC continuous beams flexurally strengthened with externally bonded FRP plates.

Keywords: continuous beams, parametric study, finite element, fiber reinforced polymer

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Authors: Maximilian Winkens, Matthias Goerke

Abstract:

The state-oriented maintenance enables the preventive intervention before the failure of a component and guarantees avoidance of expensive breakdowns. Because the timing of the maintenance is defined by the component’s state, the remaining service life can be exhausted to the limit. The basic requirement for the state-oriented maintenance is the ability to define the component’s state. New potential for this is offered by gentelligent components. They are developed at the Corporative Research Centre 653 of the German Research Foundation (DFG). Because of their sensory ability they enable the registration of stresses during the component’s use. The data is gathered and evaluated. The methodology developed determines the current state of the gentelligent component based on the gathered data. This article presents this methodology as well as current research. The main focus of the current scientific work is to improve the quality of the state determination based on the life-cycle data analysis. The methodology developed until now evaluates the data of the usage phase and based on it predicts the timing of the gentelligent component’s failure. The real failure timing though, deviate from the predicted one because the effects from the production phase aren’t considered. The goal of the current research is to develop a methodology for state determination which considers both production and usage data.

Keywords: state-oriented maintenance, life-cycle data, gentelligent component, preventive intervention

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Authors: Yantao Li, Jun Zheng

Abstract:

Food poison caused by consumption of contaminated food, especially seafood, is one of most serious public health threats worldwide. Vibrio parahaemolyticus is emerging bacterial pathogen and the leading cause of human gastroenteritis associated with food poison, especially in the southern coastal region of China. To successfully cause disease in host, bacterial pathogens need to overcome the host-derived stresses encountered during infection. One of the toxic chemical species elaborated by the host is nitric oxide (NO). NO is generated by acidified nitrite in the stomach and by enzymes of the inducible NO synthase (iNOS) in the host cell, and is toxic to bacteria. Bacterial pathogens have evolved some mechanisms to battle with this toxic stress. Such mechanisms include genes to sense NO produced from immune system and activate others to detoxify NO toxicity, and genes to repair the damage caused by toxic reactive nitrogen species (RNS) generated during NO toxic stress. However, little is known about the NO resistance in V. parahaemolyticus. In this study, a transposon coupled with next generation sequencing (Tn-seq) technology will be utilized to identify genes for NO resistance in V. parahaemolyticus. Our strategy will include construction the saturating transposon insertion library, transposon library challenging with NO, next generation sequencing (NGS), bioinformatics analysis and verification of the identified genes in vitro and in vivo.

Keywords: vibrio parahaemolyticus, nitric oxide, tn-seq, virulence

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Authors: Prakash Singh

Abstract:

In this exploratory qualitative case study, the voices of female teachers are captured that describe their fear of failure in coping with their daily anxieties, stresses, and tensions in their classrooms. When teachers are usually appointed, the curriculum forms the heart of all their professional obligations. The policy of quality and equality of education for all learners is a must as part of these deliberations, otherwise it would spell the inevitable failure for teachers. Yet, how often have teachers been asked whether they are happy during their professional tenure. Research affirms that this question is not a priority, seeing that the happiness of learners and the educational administrators enjoy precedence. Teachers are often subject to undue pressures and tensions because of environmental factors that extends beyond the curriculum. School violence, bullying, drug abuse, and gangsters are not uncommon to the school milieu, no matter where such schools can be located. In this case study, the voices of female teachers find space concerning their experiences of tobephobia (TBP). The questions that inevitably arise are: Are the educational authorities aware of the effects of TBP in education? What can be done to arrest and eliminate the debilitating effects of TBP? This exploratory study contributes to the growing concerns of TBP in education. It is therefore imperative that the effects of TBP on human resources in education must be accentuated so that meaningful solutions can be found to address challenging educational issues such as school violence, bullying, and drug abuse amongst learners.

Keywords: curriculum, female teachers, school violence, tobephobia

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Authors: Rudy Djamaluddin, Yasser Bachtiar, Rita Irmawati, Abd. Madjid Akkas, Rusdi Usman Latief

Abstract:

The aesthetic qualities and the versatility of reinforced concrete have made it a popular choice for many architects and structural engineers. Therefore, the exploration of natural materials such as gravels and sands as well as lime-stone for cement production is increasing to produce a concrete material. The exploration must affect to the environment. Therefore, the using of the concrete materials should be as efficient as possible. According to its natural behavior of the concrete material, it is strong in compression and weak in tension. Therefore the contribution of the tensile stresses of the concrete to the flexural capacity of the beams is neglected. However, removing of concrete on tension zone affects to the decreasing of flexural capacity. Introduce the strut action of truss structures may an alternative to solve the decreasing of flexural capacity. A series of specimens were prepared to clarify the effect of the truss structures in the concrete beams without concrete on the tension zone. Results indicated that the truss system is necessary for the external reinforced concrete beams. The truss system of concrete beam without concrete on tension zone (BR) could develop almost same capacity to the normal beam (BN). It can be observed also that specimens BR has lower number of cracks than specimen BN. This may be caused by the fact that there was no bonding effect on the tensile reinforcement on specimen BR to distribute the cracks.

Keywords: external reinforcement, truss, concrete beams, flexural behavior

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