Search results for: experiment under temperature change

Authors: Levent Seyfi, Ertan Akman, Tuğrul C. Topak

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In this study, irrigation automation with electronic sensors and its control with smartphones were aimed. In this context, temperature and soil humidity measurements of the area irrigated were obtained by temperature and humidity sensors. A micro controller (Arduino) was utilized for accessing values of these parameters and controlling the proposed irrigation system. The irrigation system could automatically be worked according to obtained measurement values. Besides, a GSM module used together with Arduino provided that the irrigation system was in connection to smartphones. Thus, the irrigation system can be remotely controlled. Not only can we observe whether the irrigation system is working or not via developed special android application but also we can see temperature and humidity measurement values. In addition to this, if desired, the irrigation system can be remotely and manually started or stopped regardless of measured sensor vales thanks to the developed android application. In addition to smartphones, the irrigation system can be alternatively controlled via the designed website (www.sulamadenetim.com).

Keywords: smartphone, Android Operating System, sensors, irrigation System, arduino

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Authors: Fadwa Haraka, Ahmad Elouatouati, Mourad Taha Janan

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In this study, we propose a neural network based method in order to calculate the heat source temperature of isotropic plate with lower surface forced cooling. To validate the proposed model, the heat source temperatures values will be compared to the analytical method -variables separation- and finite element model. The mathematical simulation is done through 3D numerical simulation by COMSOL software considering three different materials: Aluminum, Copper, and Graphite. The proposed method will lead to a formulation of the heat source temperature based on the thermal and geometric properties of the base plate.

Keywords: thermal model, thermal resistance, finite element simulation, neural network

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Authors: Claudineia Brazil, Elison Eduardo Bierhals, Francisco Pereira, José Leandro Néris, Matheus Rippel, Luciane Salvi

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The global concern about climate change has been increasing, since the emission of gases from human activities contributes to the greenhouse effect in the atmosphere, indicating significant impacts to the planet in the coming years. The study of precipitation regime is fundamental for the development of research in several areas. Among them are hydrology, agriculture, and electric sector. Using the climatic projections of the models belonging to the CMIP5, the main objective of the paper was to present an analysis of the impacts of climate change without rainfall in the Uruguay River basin. After an analysis of the results, it can be observed that for the future climate, there is a tendency, in relation to the present climate, for larger numbers of dry events, mainly in the winter months, changing the pluviometric regime for wet summers and drier winters. Given this projected framework, it is important to note the importance of adequate management of the existing water sources in the river basin, since the value of rainfall is reduced for the next years, it may compromise the dynamics of the ecosystems in the region. Facing climate change is fundamental issue for regions and cities all around the world. Society must improve its resilience to phenomenon impacts, and spreading the knowledge among decision makers and citizens is also essential. So, these research results can be subsidies for the decision-making in planning and management of mitigation measures and/or adaptation in south Brazil.

Keywords: climate change, hydrological potential, precipitation, mitigation

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Authors: Yang Luo, Beibei Wang

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In this paper, we present a design methodology of lightweight register transfer level (RTL) hardware threat implemented based on a MAX II FPGA platform. The dynamic power consumed by the toggling of the various bit of registers as well as the dynamic power consumed per unit of logic circuits were analyzed. The hardware threat was designed taking advantage of the differences in dynamic power consumed per unit of logic circuits to hide the transfer information. The experiment result shows that the register hardware threat was successfully implemented by using different dynamic power consumed per unit of logic circuits to hide the key information of DES encryption module. It needs more than 100000 sample curves to reduce the background noise by comparing the sample space when it completely meets the time alignment requirement. In additional, an external trigger signal is playing a very important role to detect the hardware threat in this experiment.

Keywords: side-channel analysis, hardware Trojan, register transfer level, dynamic power

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Authors: Jaruwan Duangchuen, Siwalak Pathaveerat

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Coconut (Cocos nucifera) belongs to the family Arecaceae. Coconut juice and meat are consumed as food and dessert in several regions of the world. Coconut juice contains low proteins, and arginine is the main amino acid content. Coconut meat is the endosperm of coconut that has nutritional value. It composes of carbohydrate, protein and fat. The objective of this study is utilization of by-products from the virgin coconut oil extraction process by using the skimmed coconut milk as a powder. The skimmed coconut milk was separated from the coconut milk in virgin coconut oil extraction process that consists approximately of protein 6.4%, carbohydrate 7.2%, dietary fiber 0.27 %, sugar 6.27%, fat 3.6 % and moisture content of 86.93%. This skimmed coconut milk can be made to powder for value - added product by using spray drying. The factors effect to the yield and properties of dry skimmed coconut milk in spraying process are inlet, outlet air temperature and the maltodextrin concentration. The percentage of maltodextrin content (15, 20%), outlet air temperature (80 ºC, 85 ºC, 90 ºC) and inlet air temperature (190 ºC, 200 ºC, 210 ºC) were conducted to the skimmed coconut milk spray drying process. The spray dryer was kept air flow rate (0.2698 m3 /s). The result that shown 2.22 -3.23% of moisture content, solubility, bulk density (0.4-0.67g/mL), solubility, wettability (4.04 -19.25 min) for solubility in the water, color, particle size were analyzed for the powder samples. The maximum yield (18.00%) of spray dried coconut milk powder was obtained at 210 °C of temperature, 80°C of outlet temperature and 20% maltodextrin for 27.27 second for drying time. For the amino analysis shown that the high amino acids are Glutamine (16.28%), Arginine (10.32%) and Glycerin (9.59%) by using HPLP method (UV detector).

Keywords: skimmed coconut milk, spray drying, virgin coconut oil process (VCO), maltodextrin

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Authors: Syhalath Xaphakdy, Toshio Nagata, Saykham Phommathat, Pavy Souwannavong, Vilayvanh Srithilat, Phoxay Sengdala, Bounaom Phetarnousone, Boualay Siharath, Xaya Chemcheng

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The National University of Laos (NUOL) invited a group of volunteers from the Japan International Cooperation Agency (JICA) to revise the physics experiments to utilize the materials that were already available to students. The intension was to review and revise the materials regularly utilized in physics class. The project had access to limited materials and a small budget for the class in the unit; however, by developing experimental textbooks related to mechanics, electricity, and wave and vibration, the group found a way to apply them in the classroom and enhance the students teaching activities. The aim was to introduce a way to incorporate the materials and practices in the classroom to enhance the students learning and teaching skills, particularly when they graduate and begin working as high school teachers.

Keywords: NUOL, JICA, physics experiment materials, small budget, mechanics, electricity

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Authors: Alisa Salimova, Jiane Zuo, Christopher Homer

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The objective of this study is to analyse the North Canal riparian zone land use with the help of remote sensing analysis in ArcGis using 30 cloudless Landsat8 open-source satellite images from May to August of 2013 and 2017. Land cover, urban construction, heat island effect, vegetation cover, and water system change were chosen as the main parameters and further analysed to evaluate its impact on the North Canal water quality. The methodology involved the following steps: firstly, 30 cloudless satellite images were collected from the Landsat TM image open-source database. The visual interpretation method was used to determine different land types in a catchment area. After primary and secondary classification, 28 land cover types in total were classified. Visual interpretation method was used with the help ArcGIS for the grassland monitoring, US Landsat TM remote sensing image processing with a resolution of 30 meters was used to analyse the vegetation cover. The water system was analysed using the visual interpretation method on the GIS software platform to decode the target area, water use and coverage. Monthly measurements of water temperature, pH, BOD, COD, ammonia nitrogen, total nitrogen and total phosphorus in 2013 and 2017 were taken from three locations of the North Canal in Tongzhou district. These parameters were used for water quality index calculation and compared to land-use changes. The results of this research were promising. The vegetation coverage of North Canal riparian zone in 2017 was higher than the vegetation coverage in 2013. The surface brightness temperature value was positively correlated with the vegetation coverage density and the distance from the surface of the water bodies. This indicates that the vegetation coverage and water system have a great effect on temperature regulation and urban heat island effect. Surface temperature in 2017 was higher than in 2013, indicating a global warming effect. The water volume in the river area has been partially reduced, indicating the potential water scarcity risk in North Canal watershed. Between 2013 and 2017, urban residential, industrial and mining storage land areas significantly increased compared to other land use types; however, water quality has significantly improved in 2017 compared to 2013. This observation indicates that the Tongzhou Water Restoration Plan showed positive results and water management of Tongzhou district had been improved.

Keywords: North Canal, land use, riparian vegetation, river ecology, remote sensing

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Authors: Tahir Majeed, Michael Handschuh, René Meier

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Rheumatoid arthritis patients have swelling and pain at the joints of the hand. The regions where the patient feels pain also show increased body temperature. Thermal cameras can be used to detect the rise in temperature of the affected regions. To monitor the disease progression of rheumatoid arthritis patients, they must visit the clinic regularly for scanning and examination. After scanning and evaluation, the dosage of the medicine is regulated accordingly. To monitor the disease progression over time, the correlation between the images between different visits must be established. It has been observed that by using low-cost thermal cameras, the thermal measurements do not remain the same over time, even within a single scanning. In some situations, temperatures can vary as much as 2°C within the same scanning sequence. In this paper, it has been shown that although the absolute temperature varies over time, the relative difference between the different regions remains similar. Results have been computed over four scanning sequences and are presented.

Keywords: relative thermal difference, rheumatoid arthritis, thermal imaging, thermal sensors

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Authors: Ananta Kumar Das, Sujit Kumar Chakrabarti

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Architectural tactics such as heartbeat, ping-echo, encapsulate, encrypt data are techniques that are used to achieve quality attributes of a system. Detecting architectural tactics has several benefits: it can aid system comprehension (e.g., legacy systems) and in the estimation of quality attributes such as safety, security, maintainability, etc. Architectural tactics are typically spread over the source code and are implicit. For large codebases, manual detection is often not feasible. Therefore, there is a need for automated methods of detection of architectural tactics. This paper presents a formalization of the heartbeat architectural tactic and a program analytic approach to detect this tactic in source code. The experiment of the proposed method is done on a set of Java applications. The outcome of the experiment strongly suggests that the method compares well with a manual approach in terms of its sensitivity and specificity, and far supersedes a manual exercise in terms of its scalability.

Keywords: software architecture, architectural tactics, detecting architectural tactics, program analysis, AST, alias analysis

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Authors: Mohamed Ouazene

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The insulating properties of the polymers are widely used in electrical engineering for the production of insulators and various supports, as well as for the insulation of electric cables for medium and high voltage, etc. These polymeric materials have significant advantages both technically and economically. However, although the insulation with polymeric materials has advantages, there are also certain disadvantages such as the influence of the heat which can have a detrimental effect on these materials. Polyvinyl chloride (PVC) is one of the polymers used in a plasticized state in the cable insulation to medium and high voltage. The studied material is polyvinyl chloride (PVC 4000 M) from the Algerian national oil company whose formula is: Industrial PVC 4000 M is in the form of white powder. The test sample is a pastille of 1 mm thick and 1 cm in diameter. The consequences of increasing the temperature of a polymer are modifications; some of them are reversible and others irreversible [1]. The reversible changes do not affect the chemical composition of the polymer, or its structure. They are characterized by transitions and relaxations. The glass transition temperature is an important feature of a polymer. Physical aging of PVC is to maintain the material for a longer or shorter time to its glass transition temperature. The aim of this paper is to study this phenomenon by the method of thermally stimulated depolarization currents. Relaxations within the polymer have been recorded in the form of current peaks. We have found that the intensity decreases for more residence time in the polymer along its glass transition temperature. Furthermore, it is inferred from this work that the phenomenon of physical aging can have important consequences on the properties of the polymer. It leads to a more compact rearrangement of the material and a reconstruction or reinforcement of structural connections.

Keywords: depolarization currents, glass transition temperature, physical aging, polyvinyl chloride (PVC)

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Authors: Zixuan Zhao, Lingbin Du, Le Wang, Youqing Wang, Yi Yang, Jingjun Chen, Hengjin Dong

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Objectives: Few results from public attitudes for lung cancer screening are available both in China and abroad. This study aimed to identify preferred lung cancer screening modalities in a Chinese population and predict uptake rates of different modalities. Materials and Methods: A discrete choice experiment questionnaire was administered to 392 Chinese individuals aged 50–74 years who were at high risk for lung cancer. Each choice set had two lung screening options and an option to opt-out, and respondents were asked to choose the most preferred one. Both mixed logit analysis and stepwise logistic analysis were conducted to explore whether preferences were related to respondent characteristics and identify which kinds of respondents were more likely to opt out of any screening. Results: On mixed logit analysis, attributes that were predictive of choice at 1% level of statistical significance included the screening interval, screening venue, and out-of-pocket costs. The preferred screening modality seemed to be screening by low-dose computed tomography (LDCT) + blood test once a year in a general hospital at a cost of RMB 50; this could increase the uptake rate by 0.40 compared to the baseline setting. On stepwise logistic regression, those with no endowment insurance were more likely to opt out; those who were older and housewives/househusbands, and those with a health check habit and with commercial endowment insurance were less likely to opt out from a screening programme. Conclusions: There was considerable variance between real risk and self-perceived risk of lung cancer among respondents, and further research is required in this area. Lung cancer screening uptake can be increased by offering various screening modalities, so as to help policymakers further design the screening modality.

Keywords: lung cancer, screening, China., discrete choice experiment

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Authors: Yağmur Can Gündoğan, Kübra Gürcan Bayrak, Ece Özerdem, Buse Katipoğlu, Erhan Ayas, Rifat Yılmaz

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Eutectic oxide based ceramic matrix composites have a unique microstructure that does not include grain boundary in the form of a continuous network. Because of this, these materials have the properties of perfect high-temperature strength, creep strength, and high oxidation strength. Mechanical properties of them are much related to occurring solidification structures during eutectic reactions. One of the most important production methods of this kind of material is the process of vacuum arc melting. Within scope of this studying, it is aimed to investigate the production of Al₂O₃-YAG-based eutectic ceramics by Arc melting and Spark Plasma Sintering methods for use in aerospace and defense industries where high-temperature environments play an important role and to examine the effects of ZrO₂ and LiF additions on microstructure development and mechanical properties.

Keywords: alumina, composites, eutectic, YAG

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Authors: Saima Akbar, Tahseen Ullah Khan

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The analysis of the climate change impact on flood frequency represents an important issue for water resource management and flood risk mitigation. This research was conducted to address the effects of climate change on flood incidents of Pakistan and find out gaps in existing policies to reducing the environmental aspects on floods and effects of global warming. The main objective of this research was to critically analyses the National Climate Change Policy (NCCP), National Disaster Management Authority (NDMA), Federal Flood Commission (FFC) and Vision 2025, as an effective policy document which is not only hitting the target of a climate resilient Pakistan but provides room for efficient and flexible policy implementation. The methodology integrates projected changes in monsoon patterns (since last 20 years and overall change in rainfall pattern since 1901 to 2015 from Pakistan Metrological Department), glacier melting, decreasing dam capacity and lacks in existing policies by using SWOT (Strength, Weakness, Opportunities, Threats) model in order to explore the relative impacts of global warming on the system performance. Results indicate the impacts of climate change are significant, but probably not large enough to justify a major effort for adapting the physical infrastructure to expected climatic conditions in Vision 2025 which is our shared destination to progress, ultimate aspiration to see Pakistan among the ten largest economies of the world by 2047– the centennial year of our independence. The conclusion of this research was to adapt sustainable measures to reduce flood impacts and make policies as neighboring countries are adapting for their sustainability.

Keywords: climatic factors, monsoon, Pakistan, sustainability

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Authors: Maryna Barushka, Aleh Meshyk

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The research analyzes absolute maximum soil temperatures registered at 36 gauge stations in Belarus from 1950 to 2013. The main method applied in the research is cartographic, in particular, trend surface analysis. Warming that had never been so long and intensive before started in 1988. The average temperature in January and February of that year exceeded the norm by 7-7.5 С, in March and April by 3-5С. In general, that year, as well as the year of 2008, happened to be the hottest ones in the whole period of instrumental observation. Yearly average air temperature in Belarus in those years was +8.0-8.2 С, which exceeded the norm by 2.0 – 2.2 С. The warming has been observed so far. The only exception was in 1996 when the yearly average air temperature in Belarus was below normal by 0.5 С. In Belarus the value of trend line of standard temperature deviation in the warmest months (July-August) has been positive for the past 25 years. In 2010 absolute maximum air and soil temperature exceeded the norm at 15 gauge stations in Belarus. The structure of natural processes includes global, regional, and local constituents. Trend surface analysis of the investigated characteristics makes it possible to determine global, regional, and local components. Linear trend surface shows the occurrence of weather deviations on a global scale, outside Belarus. Maximum soil temperature appears to be growing in the south-west direction with the gradient of 5.0 С. It is explained by the latitude factor. Polynomial trend surfaces show regional peculiarities of Belarus. Extreme temperature regime is formed due to some factors. The prevailing one is advection of turbulent flow of the ground layer of the atmosphere. In summer influence of the Azores High producing anticyclones is great. The Gulf Stream current forms the values of temperature trends in a year period. The most intensive flow of the Gulf Stream in the second half of winter and the second half of summer coincides with the periods of maximum temperature trends in Belarus. It is possible to estimate a local component of weather deviations in the analysis of the difference in values of the investigated characteristics and their trend surfaces. Maximum positive deviation (up to +4 С) of averaged soil temperature corresponds to the flat terrain in Pripyat Polesie, Brest Polesie, and Belarusian Poozerie Area. Negative differences correspond to the higher relief which partially compensates extreme heat regime of soils. Another important factor for maximum soil temperature in these areas is peat-bog soils with the least albedo of 8-15%. As yearly maximum soil temperature reaches 40-60 С, this could be both negative and positive factors for Belarus’s environment and economy. High temperature causes droughts resulting in crops dying and soil blowing. On the other hand, vegetation period has lengthened thanks to bigger heat resources, which allows planting such heat-loving crops as melons and grapes with appropriate irrigation. Thus, trend surface analysis allows determining global, regional, and local factors in accumulating heat in the soils of Belarus.

Keywords: soil, temperature, trend surface analysis, warming

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Authors: Tewfik Bouchaour, Salah Hamri, Yasmina Houda Bendahma, Ulrich Maschke

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Stimuli-responsive materials based on UV crosslinked acrylic polymer networks are fabricated. A various kinds of polymeric systems, hydrophilic polymers based on 2-Hydroxyethyl methacrylate have been widely studied because of their ability to simulate biological tissues, which leads to many applications. The acrylic polymer network PHEMA developed by UV photopolymerization has been used for dye retention. For these so-called smart materials, the properties change in response to an external stimulus. In this contribution, we report the influence of some parameters (initial composition, temperature, and nature of components) in the properties of final materials. Optimization of different parameters is examined by experimental design.

Keywords: UV photo-polymerization, PHEMA, external stimulus, optimization

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Authors: Trunal Bhujangrao, Catherine Froustey, Fernando Veiga, Philippe Darnis, Franck Girot Mata

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The understanding of the material behavior under shear loading has great importance for a researcher in manufacturing processes like cutting, machining, milling, turning, friction stir welding, etc. where the material experiences large deformation at high temperature. For such material behavior analysis, hot shear tests provide a useful means to investigate the evolution of the microstructure at a wide range of temperature and to improve the material behavior model. Shear tests can be performed by direct shear loading (e.g. torsion of thin-walled tubular samples), or appropriate specimen design to convert a tensile or compressive load into shear (e.g. simple shear tests). The simple shear tests are straightforward and designed to obtained very large deformation. However, many of these shear tests are concerned only with the elastic response of the material. It is becoming increasingly important to capture a plastic response of the material. Plastic deformation is significantly more complex and is known to depend more heavily on the strain rate, temperature, deformation, etc. Besides, there is not enough work is done on high-temperature shear loading, because of geometrical instability occurred during the plastic deformation. The aim of this study is to design a new shear tensile specimen geometry to convert the tensile load into dominant shear loading under plastic deformation. Design of the specimen geometry is based on FEM. The material used in this paper is AA7075 alloy, tested quasi statically under elevated temperature. Finally, the microstructural changes taking place during

Keywords: AA7075 alloy, dynamic recrystallization, edge effect, large strain, shear tensile test

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Authors: Mahdi Asghari

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The cavitation phenomenon is the formation and production of micro-bubbles and eventually the bursting of the micro-bubbles inside the liquid fluid, which results in localized high pressure and temperature, causing physical and chemical fluid changes. This pressure and temperature are predicted to be 2000 atmospheres and 5000 °C, respectively. As a result of small bubbles bursting from this process, temperature and pressure increase momentarily and locally, so that the intensity and magnitude of these temperatures and pressures provide the energy needed to break the molecular bonds of heavy compounds such as fuel oil. In this paper, we study the theory of cavitation and the methods of cavitation production by acoustic and hydrodynamic methods and the necessary mechanical equipment and reactors for industrial application of the hydrodynamic cavitation method to break down the molecular bonds of the fuel oil and convert it into useful and economical products.

Keywords: Cavitation, Hydrodynamic Cavitation, Cavitation Reactor, Fuel Oil

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Authors: Ranjit A. Patil, Yung Liou, Yuan-Ron Ma

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It has been observed that when the size of metals such as, Au, Zn, Ag, Cu, Te, and metal oxides is reduced to several nano-meters, it starts to show further interesting properties. These new properties boost the use of nano-structures to produce attractive functional materials or used as promising building blocks in electronic devices. Present work describes the synthesis of bismuth (Bi) nanoparticles (NP’s) having uniform morphology, high crystallinity, and single phase purity by the temperature assisted pulsed laser deposition (TAPLD). Pulsed Laser deposition (PLD) technique is one of the promising methods to synthesize nano-structures. It can provide the stable nucleation sites in orders of magnitudes higher than for MBE and sputtering deposition. The desired size of purely metallic Bi NP’s of can be easily controlled by adjusting the temperature of the substrate varying from 1000 C to 250 0C. When the temperatures of the substrate raised step wise the average size of Bi NP’s appeared to be increased by maintaining the uniform distribution of NP’s on the Si surfaces. The diameter range of NP’s is ~33-84 nm shows size distribution constrained in the limited range. The EDS results show that the 0D Bi NP’s synthesized at high temperature (250 0C) at a high vacuum still remained in a metallic phase. Moreover, XRD, TEM and SAED results showed that these Bi NP’s are hexagonal in crystalline in a space group R -3 m and no traces of bismuth oxide, confirming that Bi NP’s synthesized at wide range of temperatures persisted of the pure Bi-metallic phase.

Keywords: metal nano particles, bismuth, pulsed laser deposition (PLD), nano particles, temperature assisted growth

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Authors: Ramy Hammady, Sylvester Arnab

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Significant attention has been directed to adopt game interventions practically to change certain behaviours in many disciplines such as health, education, psychology through many years. That’s due to the intrinsic motivation that games can cause and the substantial impact the games can leave on the player. Many review papers were induced to highlight and measure the effectiveness of the game’s interventions on changing behaviours; however, most of these studies neglected the game design process itself and the game features and elements that can stimuli changing behaviours. Therefore, this paper aims to identify the most game design mechanics and features that are the most influencing on changing behaviour during or after games interventions. This paper also sheds light on the theories of changing behaviours that clearly can led the game design process. This study gives directions to game designers to spot the most influential game features and mechanics for changing behaviour games in order to exploit it on the same manner.

Keywords: behaviour change, game design, serious gaming, gamification, review

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Authors: Hany Mustafa, Mahmoud Roushdi, Khaled Kheireldin

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Rainfall variability is an important feature of semi-arid climates. Climate change is very likely to increase the frequency, magnitude, and variability of extreme weather events such as droughts, floods, and storms. The Blue Nile Basin is facing extreme climate change-related events such as floods and droughts and its possible impacts on ecosystem, livelihood, agriculture, livestock, and biodiversity are expected. Rainfall variability is a threat to food production in the Blue Nile Basin countries. This study investigates the long-term variations and trends of seasonal and annual precipitation over the Blue Nile Basin for 102-year period (1901-2002). Six statistical trend analysis of precipitation was performed with nonparametric Mann-Kendall test and Sen's slope estimator. On the other hands, four statistical absolute homogeneity tests: Standard Normal Homogeneity Test, Buishand Range test, Pettitt test and the Von Neumann ratio test were applied to test the homogeneity of the rainfall data, using XLSTAT software, which results of p-valueless than alpha=0.05, were significant. The percentages of significant trends obtained for each parameter in the different seasons are presented. The study recommends adaptation strategies to be streamlined to relevant policies, enhancing local farmers’ adaptive capacity for facing future climate change effects.

Keywords: Blue Nile basin, climate change, Mann-Kendall test, trend analysis

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Authors: Robert Setekera, Ramses van der Toorn

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We present an extensive analysis of the temperature dependence of the local avalanche model used in most of the modern compact models for bipolar transistors. This local avalanche model uses the Chynoweth's empirical law for ionization coefficient to define the generation of the avalanche current in terms of the local electric field. We carry out the model analysis using DC-measurements taken on both Si and advanced SiGe bipolar transistors. For the advanced industrial SiGe-HBTs, we consider both high-speed and high-power devices (both NPN and PNP transistors). The limitations of the local avalanche model in modeling the temperature dependence of the avalanche current mostly in the weak avalanche region are demonstrated. In addition, the model avalanche parameters are analyzed to see if they are in agreement with semiconductor device physics.

Keywords: avalanche multiplication, avalanche current, bipolar transistors, compact modeling, electric field, impact ionization, local avalanche

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Authors: Andrey A. Chernousov, Ben Y. B. Chan

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The use of the low-cost paraffinic phase change material can be rather effective in smart building envelopes in the South China region. Particular attention has to be paid to the PCM optimization as an exploitation conditions and the envelope insulation changes its thermal characteristics. The studied smart building envelope consists of a reinforced aluminum exterior, polymeric insulation foam, phase change material and reinforced interior gypsum board. A prototype sample was tested to validate the numerical scheme using EnergryPlus software. Three scenarios of insulation thermal resistance loss (ΔR/R = 0%, 25%, 50%) were compared with the different PCM thicknesses (tP=0, 1, 2.5, 5 mm). The comparisons were carried out for a west facing enveloped office building (50 storey). PCM optimization was applied to find the maximum efficiency for the different ΔR/R cases. It was found, during the optimization, that the PCM is an important smart component, lowering the peak energy demand up to 2.7 times. The results are not influenced by the insulation aging in terms of ΔR/R during long-term exploitation. In hot and humid climates like Hong Kong, the insulation core of the smart systems is recommended to be laminated completely. This can be very helpful in achieving an acceptable payback period.

Keywords: smart building envelope, thermal performance, phase change material, energy efficiency, large-scale sandwich panel

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Authors: Mengjun Zhang, Yuli Sun, Dunwen Zuo, Chunxiang Xie, Chunming Zhang

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Experimental study on slicing of sapphire with fixed abrasive diamond wire saw was conducted in this paper. The process parameters were optimized through orthogonal experiment of three factors and four levels. The effects of wire speed, feed speed and tension pressure on the surface roughness were analyzed. Surface roughness in cutting direction and feed direction were both detected. The results show that feed speed plays the most significant role on the surface roughness of sliced sapphire followed by wire speed and tension pressure. The optimized process parameters are as follows: wire speed 1.9 m/s, feed speed 0.187 mm/min and tension pressure 0.18 MPa. In the end, the results were verified by analysis of variance.

Keywords: fixed abrasive, diamond wire saw, slicing, sapphire, orthogonal experiment

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Authors: Angelika-Ioanna Gialleli, Gousi Mantha, Maria Kanellaki, Bekatorou Argyro, Athanasios Koutinas

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In this study, a new brewing technology with dry raw materials is proposed with potential application in home brewing. Bio catalysts were prepared by immobilization of the psychrotolerant yeast strain Saccharomyces cerevisiae AXAZ-1 on tubular cellulose. Both the word and the biocatalysts were freeze-dried without any cryoprotectants and used for low temperature brewing. The combination of immobilization and freeze-drying techniques was applied successfully, giving a potential for supplying breweries with preserved and ready-to-use immobilized cells. The effect of wort sugar concentration (7°, 8.5°, 10°Be), temperature (2, 5, 7° C) and carrier concentration (5, 10, 20 g/L) on fermentation kinetics and final product quality (volatiles, colour, polyphenols, bitterness) was assessed. The same procedure was repeated with free cells for comparison of the results. The results for immobilized cells were better compared to free cells regarding fermentation kinetics and organoleptic characteristics.

Keywords: brewing, tubular cellulose, low temperature, biocatalyst

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Authors: Vigen Barkhudaryan

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The influence of external effects (γ-, UV–radiations, high temperature) in presence of air oxygen on structural transformations of low-density polyethylene (LDPE) have been investigated dependent on the polymers’ thickness, the intensity and the dose of external actions. The methods of viscosimetry, light scattering, turbidimetry and gelation measuring were used for this purpose. The comparison of influence of external effects on LDPE shows, that the destruction and cross-linking processes of macromolecules proceed simultaneously with all kinds of external effects. A remarkable growth of average molecular mass of LDPE along with the irradiation doses and heat treatment exposure growth was established. It was linear for the mass average molecular mass and at the initial doses is mainly the result of the increase of the macromolecular branching. As a result, the macromolecular hydrodynamic volumes have been changed, and therefore the dependence of viscosity average molecular mass on the doses was going through the minimum at initial doses. A significant change of molecular mass, sizes and shape of macromolecules of LDPE occurs under the influence of external effects. The influence is limited only by diffusion of oxygen during -irradiation and heat treatment. At UV–irradiation the influence is limited both by diffusion of oxygen and penetration of radiation. Consequently, the molecular transformations are deeper and evident in case of -irradiation, as soon as the polymer is transformed in a whole volume. It was also established, that the mechanism of molecular transformations in polymers from the surface layer distinctly differs from those of the sample deeper layer. A comparison of the results of these investigations allows us to conclude, that the mechanisms of influence of investigated external effects on polyethylene are similar.

Keywords: cross-linking, destruction, high temperature, LDPE, γ-radiations, UV-radiations

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Authors: P. Mukhopadhyay, N. C. Dey

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Occupational health hazard is a very common term in every emerging country. Along with the unorganized sector, most organized sectors including government industries are suffering from this affliction. In addition to workload, the seasonal changes also have some impacts on working environment. With this focus in mind, one hundred male industrial workers, who are directly involved to the task of Periodic Overhauling (POH) in a fabricating workshop in the public domain are selected for this research work. They have been studied during work periods throughout different seasons in a year. For each and every season, the participants working heart rate (WHR) is measured and compared with the standards given by different national and internationally recognized agencies i.e., World Health Organization (WHO) and American Conference of Governmental Industrial Hygienists (ACGIH) etc. The different environmental parameters i.e. dry bulb temperature (DBT), wet bulb temperature (WBT), globe temperature (GT), natural wet bulb temperature (NWB), relative humidity (RH), wet bulb globe temperature (WBGT), air velocity (AV), effective temperature (ET) are recorded throughout the seasons to critically observe the effect of seasonal changes on the WHR of the workers. The effect of changes in environment to the WHR of the workers is very much surprising. It is found that the percentages of workers who belong to the ‘very heavy’ workload category are 83.33%, 66.66% and 16.66% in the summer, rainy and winter seasons, respectively. Ongoing undertaking of this type of job profile forces the worker towards occupational disorders causing absenteeism. This occurrence results in lower production rates, and on the other hand, costs due to medical claims also weaken the industry’s economic condition. In this circumstance, the authors are trying to focus on some remedial measures from the ergonomic angle by proposing a new work/ rest regimen and introducing engineering controls along with management controls which may help the worker, and consequently, the management also.

Keywords: workload, working heart rate, occupational health hazard, industrial worker

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Authors: Kukuh Suprayogi, Muhamad Natsir, Olif Kurniawan, Hot Parulian, Bayu Fitriana, Fery Mustofa

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The new approach by utilizing the heat propagation analysis carried out by studying and evaluating the effect of the presence of hydrocarbons to the flow of heat that goes from the bottom surface to surface. Heat propagation is determined by the thermal conductivity of rocks. The thermal conductivity of rock itself is a quantity that describes the ability of a rock to deliver heat. This quantity depends on the constituent rock lithology, large porosity, and pore fluid filler. The higher the thermal conductivity of a rock, the more easily the flow of heat passing through these rocks. With the same sense, the heat flow will more easily pass through the rock when the rock is filled with water than hydrocarbons, given the nature of the hydrocarbons having more insulator against heat. The main objective of this research is to try to make the model the heat propagation calculations in degrees Celsius from the subsurface to the surface which is then compared with the surface temperature is measured directly at the point of location. In calculating the propagation of heat, we need to first determine the thermal conductivity of rocks, where the rocks at the point calculation are not composed of homogeneous but consist of strata. Therefore, we need to determine the mineral constituent and porosity values of each stratum. As for the parameters of pore fluid filler, we assume that all the pores filled with water. Once we get a thermal conductivity value of each unit of the rock, then we begin to model the propagation of heat profile from the bottom to the surface. The initial value of the temperature that we use comes from the data bottom hole temperature (BHT) is obtained from drilling results. Results of calculations per depths the temperature is displayed in plotting temperature versus depth profiles that describe the propagation of heat from the bottom of the well to the surface, note that pore fluid is water. In the technical implementation, we can identify the magnitude of the effect of hydrocarbons in reducing the amount of heat that crept to the surface based on the calculation of propagation of heat at a certain point and compared with measurements of surface temperature at that point, assuming that the surface temperature measured is the temperature that comes from the asthenosphere. This publication proves that the accumulation of hydrocarbon can be identified by analysis of heat propagation profile which could be a method for identifying the presence of hydrocarbons.

Keywords: thermal conductivity, rock, pore fluid, heat propagation

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Authors: Ji-Hoon Byeon, Kwon-Hee Lee

Abstract:

Strainer filter serves to block the inflow of impurities while mixed fluid is entering or exiting the piping. The filter of the strainer has a perforated structure, so that the pressure drop and the velocity change necessarily occur when the mixed fluid passes through the filter. It is possible to predict the pressure drop and velocity change of the strainer by numerical analysis by implementing all the perforated plates. However, if the size of the perforated plate exceeds a certain size, it is difficult to perform the numerical analysis, and sometimes we cannot guarantee its accuracy. In this study, we tried to predict the pressure drop and velocity change by using the porous media technique to obtain the equivalent resistance without actual implementation of the perforation shape of the strainer. Ansys-CFX, a commercial software, is used to perform the numerical analysis. The analysis procedure is as follows. Firstly, the unit pattern of the perforated plate is modeled, and the pressure drop is analyzed by varying the velocity by symmetry of the wall surface. Secondly, since the equation for obtaining resistance is a quadratic equation of pressure having unknown velocity, the viscous resistance and the inertia resistance of the perforated plate are obtained from the relationship between pressure and speed. Thirdly, by using the calculated resistance values, the values are substituted into the flat plate implemented as a two-dimensional porous media, and the accuracy is verified by comparing the pressure drop and the velocity change. Fourthly, the pressure drop and velocity change in the whole strainer are analyzed by using the resistance values obtained on the perforated plate in the actual whole strainer model. Using the porous media technique, it is found that pressure drop and velocity change can be predicted in relatively short time without modeling the overall shape of the filter. Acknowledgements: This work was supported by the Valve Center from the Regional Innovation Center(RIC) Program of Ministry of Trade, Industry & Energy (MOTIE).

Keywords: strainer, porous media, CFD, numerical analysis

Procedia PDF Downloads 363

Authors: Qianli Ma, Xuemin Zhao, Lingai Yao, Zhencheng Xu, Li Wang

Abstract:

Heavy metal pollution accidents, frequently happened in this decade in China, severely threaten aquatic ecosystem and economy. In January 2012, a basin-scale accidental Cd pollution happened in Longjiang River in southwest China. Although water quality was recovered in short period by emergency treatment with flocculants, a large amount of contaminated cage-cultivated fish were left with the task of preventing or mitigating Cd contamination of fish. In this study, unpolluted Ctenopharyngodon idellus were fed by Cd-contaminated macrophytes for assessing the effect of Cd accumulation through food exposure, and the contaminated C. idellus were fed with Cd-free macrophytes for assessing the ability of Cd depuration. The on-site cultivation experiments were done in two sites of Lalang (S1, accidental Cd pollution originated) and Sancha (S2, a large amount of flocculants were added to accelerate Cd precipitation) in Longjiang river. Results showed that Cd content in fish muscle presented an increasing trend in the accumulation experiment. In S1, Cd content of fish muscle rose sharply from day 8 to day 18 with higher average Cd content in macrophytes and sediment, and kept in the range of 0.208-0.308 mg/kg afterward. In S2, Cd content of fish muscle rose gradually throughout the experiment and reached the maximum level of 0.285 mg/kg on day 76. The results of the depuration experiment showed that Cd content in fish muscle decreased and significant changes were observed in the first half time of the experiment. Meanwhile, fish with lower initial Cd content presented higher elimination constant. In S1, Cd content of fish significantly decreased from 0.713 to 0.304 mg/kg in 18 days and kept decreasing to 0.110 mg/kg in the end, and 84.6% of Cd content was eliminated. While in S2, there was a sharp decrease of Cd content of fish in 0-8 days from 0.355 mg/kg to 0.069 mg/kg. The total elimination percentage was 93.8% and 80.6% of which appeared in day 0-8. The elimination constant of fish in S2 was 0.03 which was higher than 0.02 in S1. Collectively, our results showed Cd could be absorbed through food exposure and accumulate in fish muscle, and the accumulated Cd in fish muscle can be excreted after isolated from the polluted food sources. This knowledge allows managers to assess health risk of Cd contaminated fish and minimize aquaculture loss when considering fish cultivation after accidental pollution.

Keywords: accidental pollution, cadmium accumulation and depuration, cage-cultivated fish, environmental management, river

Procedia PDF Downloads 248

Authors: M. A. Hannan, N. Matthias Neisius

Abstract:

Organophosphorus compound diethyloxymethyl-9-oxa-10-phosphaphenanthrene-10-oxide (DOPAC) was applied on cotton cellulose to impart eco-friendly flame retardant property to it. Here acetal linkage was introduced rather than conventionally used ester linkage to rescue from the undurability problem of flame retardant compound. Some acidic catalysts, sodium dihydrogen phosphate (NaH2PO4), ammonium dihydrogen phosphate (NH4H2PO4) and phosphoric acid (H3PO4) were successfully used to form acetal linkage between the base material and flame retardant compound. Inspiring limiting oxygen index (LOI) value of 22.4 was found after exclusive washing treatment. A good outcome of total heat of combustion (THC) 6.05 KJ/g was found possible during pyrolysis combustion flow calorimetry (PCFC) test of the treated sample. Low temperature dehydration with sufficient amount of char residue (14.89%) was experienced in case of treated sample. In addition, the temperature of peak heat release rate (TPHRR) 343.061°C supported the expected low temperature pyrolysis in condensed phase mechanism. With the consequence of pyrolysis effects, thermogravimetric analysis (TGA) also reported inspiring weight retention% of the treated samples.

Keywords: acetal linkage, char residue, cotton cellulose, flame retardant, loi, low temperature pyrolysis, organophosphorus, THC, THRR

Procedia PDF Downloads 292