Search results for: hot bomb conditions

Authors: Seon Soon Choi

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The essential purpose is to present the good fatigue crack propagation model describing a stochastic fatigue crack growth behavior in a rolled magnesium alloy, AZ31, under various load ratio conditions. Fatigue crack propagation experiments were carried out in laboratory air under four conditions of load ratio, R, using AZ31 to investigate the crack growth behavior. The stochastic fatigue crack growth behavior was analyzed using an interpolation of random variable, Z, introduced to an empirical fatigue crack propagation model. The empirical fatigue models used in this study are Paris-Erdogan model, Walker model, Forman model, and modified Forman model. It was found that the random variable is useful in describing the stochastic fatigue crack growth behaviors under various load ratio conditions. The good probabilistic model describing a stochastic fatigue crack growth behavior under various load ratio conditions was also proposed.

Keywords: magnesium alloys, fatigue crack propagation model, load ratio, interpolation of random variable

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Authors: Turan Çalban, Oral Laçin, Abdüsselam Kurtbaş

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The experimental production methods Chevreul’s salt being a intermediate stage product for copper recovery were investigated by dealing with the articles written on this topic. Chevreul’s salt, Cu2SO3.CuSO3.2H2O, being a mixed valence copper sulphite compound has been obtained by using different methods and reagents. Chevreul’s salt has a intense brick-red color. It is a highly stable and expensive salt. The production of Chevreul’s salt plays a key role in hiydrometallurgy. In recent years, researchs on this compound have been intensified. Silva et al. reported that this salt is thermally stable up to 200oC. Çolak et al. precipitated the Chevreul’s salt by using ammonia and sulphur dioxide. Çalban et al. obtained at the optimum conditions by passing SO2 from leach solutions with NH3-(NH4)2SO4. Yeşiryurt and Çalban investigated the optimum precipitation conditions of Chevreul’s salt from synthetic CuSO4 solutions including Na2SO3. Çalban et al. achieved the precipitation of Chevreul’s salt at the optimum conditions by passing SO2 from synthetic CuSO4 solutions. Çalban et al. examined the precipitation conditions of Chevreul’s salt using (NH4)2SO3 from synthetic aqueous CuSO4 solutions. In light of these studies, it can be said that Chevreul’s salt can be produced practically from both a leach solutions including copper and synthetic CuSO4 solutions.

Keywords: Chevreul’s salt, ammonia, copper sulpfite, sodium sülfite, optimum conditions

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Authors: Kunihisa Kakumoto

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This technical paper is for the prototype of solar energy utilization for finding sustainable conditions. This model has been simulated under the climate conditions in Japan. At the beginning of the study, the solar model house was built up on site. And the concerned data was collected in this model house for several years. On the basis of these collected data, the concept on the solar community was built up. For the finding sustainable conditions, the amount of the solar energy generation and its reduction of carbon dioxide and the reduction of carbon dioxide by the green planting and the amount of carbon dioxide according to the normal daily life in the solar community and the amount of the necessary water for the daily life in the solar community and the amount of the water supply by the rainfall on-site were calculated. These all values were taken into consideration. The relations between each calculated result are shown in the expression of inequality. This solar community and its consideration for finding sustainable conditions can be one prototype to do the feasibility study for our life in the future

Keywords: carbon dioxide, green planting, smart city, solar community, sustainable condition, water activity

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Authors: Beate Niemann, Fabian Pramel

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The formerly industrially or militarily used Urban Waterfront is a potential area for urban development. Extensive interventions in the urban space come along with the development of these previously inaccessible areas in the city. The development of the Urban Waterfront in the European City is not subject to any recognizable urban paradigm. In this study, the development of the Urban Waterfront as a new urban space typology is analyzed by case studies of Urban Waterfront developments in European Cities. For humans, perceptible spatial conditions are categorized and it is identified whether the themed Urban Waterfront Developments are congruent or incongruent urban design interventions and which deviations the Urban Waterfront itself induce. As congruent urban design, a design is understood, which fits in the urban fabric regarding its similar spatial conditions to the surrounding. Incongruent urban design, however, shows significantly different conditions in its shape. Finally, the spatial relationship of the themed Urban Waterfront developments and their associated environment are compared in order to identify contrasts between new and old urban space. In this way, conclusions about urban design paradigms of the new urban space typology are tried to be drawn.

Keywords: composition, congruence, identity, paradigm, spatial condition, urban design, urban development, urban waterfront

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Authors: Adrian Reynaldo Sudirman, Siti Farida, Aisyah Aminy Maulidina, Caren Andika Surbakti

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Sedentary lifestyle and imbalance consumption pattern has made metabolic syndrome as the global time bomb phenomenon in the world. The increasing tendency of people in consuming high amount of fructose and cholesterol food has worsened this issue in the society. Pancreas steatosis become one of the most comorbid when early diagnosis and prompt treatment has not been applied on hyperglycemic and hyperlipidemic condition in metabolic syndrome patient. Gemfibrozil become the drug of choice to prevent this issue, yet the efficacy of this regiment was still questionable. Acalypha indica Linn. is the herb that has protective effect on hyperlipidemic and hyperglycemic condition. This study was aimed to compare therapeutic effect of gemfibrozil (G) and Acalypha indica Linn. (AI) on high fructose and cholesterol diet-induced pancreas steatosis in Sprague-Dawley mice. The post induction mice were divided into four groups: control, gemfibrozil, AI extract, and G+AI combination regiment. Each group received four weeks intervention. The result of statistical analysis using the One-Way ANOVA test and Tukey Post Hoc test showed significant decrease in pancreatic steatosis between the control group and administered Acalypha indica group (p = 0.004, 95% CI: 0.170-0.959) and the group administered with a combination of Gemfibrozil-Acalypha indica (p = 0.023, 95% CI: 0.537-0.813). The protective effect of Acalypha indica Linn. shows that this plant has the potential as therapeutic option in overcoming the condition of pancreas steatosis in metabolic syndrome.

Keywords: Acalypha Indica Linn., Cholesterol, Fructose, Gemfibrozil, Pancreas Steatosis

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Authors: Saskya E. Carrera P., Ben Hankamer, Melanie Oey

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The green alga C. reinhardtii provides a platform for the cheap, scalable, and safe production of complex proteins. Despite gene expression in photosynthetic organisms being tightly regulated by light, most expression studies have analysed chloroplast recombinant protein production under constant light. Here the influence of illumination time and intensity on GFP and a GFP-PlyGBS (bacterial-lysin) fusion protein expression was investigated. The expression of both proteins was strongly influenced by the light regime (6-24 hr illumination per day), the light intensity (0-450 E m⁻²s⁻¹) and growth condition (photoautotrophic, mixotrophic and heterotrophic). Heterotrophic conditions resulted in relatively low recombinant protein yields per unit volume, despite high protein yields per cell, due to low growth rates. Mixotrophic conditions exhibited the highest yields at 6 hrs illumination at 200µE m⁻²s⁻¹ and under continuous low light illumination (13-16 mg L⁻¹ GFP and 1.2-1.6 mg L⁻¹ GFP-PlyGBS), as these conditions supported good cell growth and cellular protein yields. A ~23-fold increase in protein accumulation per cell and ~9-fold increase L⁻¹ culture was observed compared to standard constant 24 hr illumination for GFP-PlyGBS. The highest yields under photoautotrophic conditions were obtained under 9 hrs illumination (6 mg L⁻¹ GFP and 2.1 mg L⁻¹ GFP-PlyGBS). This represents a ~4-fold increase in cellular protein accumulation for GFP-PlyGBS. On a volumetric basis the highest yield was at 15 hrs illumination (~2-fold increase L⁻¹ over the constant light for GFP-PlyGBS). Optimising illumination conditions to balance growth and protein expression can thus significantly enhance overall recombinant protein production in C. reinhardtii cultures.

Keywords: chlamydomonas reinhardtii, light, mixotrophic, recombinant protein

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Authors: S. K. Thind, Neha Gupta

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Glycine betaine (N, N’, N’’– trimethyl glycine), (GB) as aqueous solution (100 mM) containing 0.1% TWEEN-20 (Ploythylene glycol sorbitan monolaurate) was sprayed on selected nineteen wheat genotypes at maximum tillering and anthesis stages. Water-deficit conditions resulted in lipid peroxidation. GB applications reduced lipid peroxidation in all wheat genotypes at both the stages. Catalase (CAT) activity was recorded more in control than under stressed conditions in selected wheat genotypes at both the stages; GB had no effect. The ascorbic acid content in leaves of selected genotypes increased under water deficit. A genotypic variability in Ascorbate peroxidase (APx) activity was recorded and GB treatment decreased it. Superoxide dismutase (SOD) activity was increased significantly under water-deficit at both stages in all genotypes. In present study, prolonged water-deficit conditions caused CAT deficiency/suppression which was compensated by APX and SOD; and GB exogenous application mitigated negative effect of water-deficit stress on lipid peroxidation.

Keywords: glycine-betaine, lipid peroxidation, ROS, water deficit stress

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Authors: Jian Li

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The uncertainty quantification and inversion problems of subsurface oil-water phase flow usually require extensive repeated forward calculations for new runs with changed conditions. To reduce the computational time, various forms of surrogate models have been built. Related research shows that deep learning has emerged as an effective surrogate model, while most surrogate models with deep learning are purely data-driven, which always leads to poor robustness and abnormal results. To guarantee the model more consistent with the physical laws, a coupled theory-guided convolutional neural network (TgCNN) based surrogate model is built to facilitate computation efficiency under the premise of satisfactory accuracy. The model is a convolutional neural network based on multi-well reservoir simulation. The core notion of this proposed method is to bridge two separate blocks on top of an overall network. They underlie the TgCNN model in a coupled form, which reflects the coupling nature of pressure and water saturation in the two-phase flow equation. The model is driven by not only labeled data but also scientific theories, including governing equations, stochastic parameterization, boundary, and initial conditions, well conditions, and expert knowledge. The results show that the TgCNN-based surrogate model exhibits satisfactory accuracy and efficiency in subsurface oil-water phase flow under multi-well conditions.

Keywords: coupled theory-guided convolutional neural network, multi-well conditions, surrogate model, subsurface oil-water phase

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Authors: M. Y. Malika, Farzana, Abdul Rehman

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The study deals with the steady, 3D MHD boundary layer flow of a non-Newtonian Maxwell fluid flow due to a horizontal surface stretched exponentially in two lateral directions. The temperature at the boundary is assumed to be distributed exponentially and possesses convective boundary conditions. The governing nonlinear system of partial differential equations along with associated boundary conditions is simplified using a suitable transformation and the obtained set of ordinary differential equations is solved through numerical techniques. The effects of important involved parameters associated with fluid flow and heat flux are shown through graphs.

Keywords: boundary layer flow, exponentially stretched surface, Maxwell fluid, numerical solution

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Authors: Samir Assal

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This paper considers an international sample of venture capital and private equity funds to assess the role of law, corruption and culture in setting fund manager fees in terms of their fixed management fees, carried interest performance fees, clawbacks of fees and cash versus share distributions of fees. The data highlight a role of legal conditions in shaping fees paid to fund managers. In countries with better legal conditions, fixed fees are lower, carried interest fees are higher, clawbacks are less likely, and share distributions are more likely. These findings suggest legal conditions help to align the interests of managers and shareholders. More specifically, we examine which element of legal conditions matter most, and discover that corruption levels play a pronounced role in shaping fund manager fee contracts. We also show that cultural forces such as Hofstede’s measures of power distance and uncertainty avoidance likewise play a role in influencing fees.

Keywords: managerial compensation, incentive contracts, private equity, law and finance

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Authors: M. Abdullah Al Faruque, Ram Balachandar

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An experimental study with four different types of bed conditions was carried out to understand the effect of roughness in open channel flow at two different Reynolds numbers. The bed conditions include a smooth surface and three different roughness conditions which were generated using sand grains with a median diameter of 2.46 mm. The three rough conditions include a surface with distributed roughness, a surface with continuously distributed roughness and a sand bed with a permeable interface. A commercial two-component fibre-optic LDA system was used to conduct the velocity measurements. The variables of interest include the mean velocity, turbulence intensity, the correlation between the streamwise and the wall normal turbulence, Reynolds shear stress and velocity triple products. Quadrant decomposition was used to extract the magnitude of the Reynolds shear stress of the turbulent bursting events. The effect of roughness was evident throughout the flow depth. The results show that distributed roughness has the greatest roughness effect followed by the sand bed and the continuous roughness. Compared to the smooth bed, the streamwise turbulence intensity reduces but the vertical turbulence intensity increases at a location very close to the bed due to the introduction of roughness. Although the same sand grain is used to create the three different rough bed conditions, the difference in the turbulence intensity is an indication that the specific geometry of the roughness has an influence on turbulence structure.

Keywords: open channel flow, smooth and rough bed, Reynolds number, turbulence

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Authors: M. Sajjadnejad, H. Karimi Abadeh

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In this research, zinc coatings were fabricated by electroplating process in a sulfate solution under direct and pulse current conditions. In direct and pulse current conditions, effect of maximum current was investigated on the coating properties. Also a comparison was made between the obtained coatings under direct and pulse current. Morphology of the coatings was investigated by scanning electron microscopy (SEM). Corrosion behavior of the coatings was investigated by potentiodynamic polarization test. In pulse current conditions, the effect of pulse frequency and duty cycle was also studied. The effect of these conditions and parameters were also investigated on morphology and corrosion behavior. All of DC plated coatings are showing a distinct passivation area in -1 to -0.4 V range. Pulsed current coatings possessed a higher corrosion resistance. The results showed that current density is the most important factor regarding the fabrication process. Furthermore, a rise in duty cycle deteriorated corrosion resistance of coatings. Pulsed plated coatings performed almost 10 times better than DC plated coatings.

Keywords: corrosion, duty cycle, pulsed current, zinc

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Authors: Mostafa M. Makrahy, Nouby M. Ghazaly, G. T. Abd el-Jaber

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This paper presents the experimental study of vibration generated by friction materials of an automotive disc brake system using brake test rig. Effects of silica sand particles which are available on the road surface as an environmental condition with a size varied from 150 μm to 600 μm are evaluated. Also, the vibration of the brake disc is examined against the friction material in humidity environment conditions under variable rotational speed. The experimental results showed that the silica sand particles have significant contribution on the value of vibration amplitude which enhances with increasing the size of silica sand particles at different speed conditions. Also, it is noticed that the friction material is sensitive to humidity and the vibration magnitude increases under wet testing conditions. Moreover, it can be reported that with increasing the applied pressure and rotational speed of the braking system, the vibration amplitudes decrease for all cases.

Keywords: disc brake vibration, friction-induced vibration, silica sand particles, brake operational and environmental conditions

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Authors: Jonathan H. Westover, Maureen S. Andrade, Angela Schill, Jeff Peterson, Samuel Choi

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The purpose of this research is to understand employee perspectives on their work characteristics and conditions, particularly related to the COVID-19 pandemic and the future of work. Working conditions impact job satisfaction. People tend to measure job satisfaction by comparing aspects of the job they have with those they want. Job satisfaction is related to the value that one places on specific aspects of a job, such as autonomy, pay and benefits, challenge, growth, or meaningful work, and the degree to which such elements are present. The value one places on these various job characteristics may differ based on gender, age, personality, occupation, context, or other factors. This study will examine various job characteristics and working conditions with an emphasis on COVID-19 to determine how managers and leaders and better support and develop their employees.

Keywords: COVID-19, employee perspectives nature of work, future of work

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Authors: Dmitry Fedoseyev

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The ultimate success of unmanned aerial vehicles (UAVs) depends largely on the effective control of their flight, especially in variable wind conditions. This paper investigates different approaches to selecting the optimal flight level to maximize the range of UAVs. We propose to consider methods based on mathematical models of atmospheric conditions, as well as the use of sensor data and machine learning algorithms to automatically optimize the flight level in real-time. The proposed approaches promise to improve the efficiency and range of UAVs in various wind conditions, which may have significant implications for the application of these systems in various fields, including geodesy, environmental surveillance, and search and rescue operations.

Keywords: drone, UAV, flight trajectory, wind-searching, efficiency

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Authors: Wooseok Song, Sunjung Park, Jongkwon Lee, Jaye Koo

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The objective of this paper is to observe the effects of injection conditions on flame structures in gas-centered swirl coaxial injector. Gaseous oxygen and liquid kerosene were used as propellants. For different injection conditions, two types of injector, which only differ in the diameter of the tangential inlet, were used in this study. In addition, oxidizer injection pressure was varied to control the combustion chamber pressure in different types of injector. In order to analyze the combustion instability intensity, the dynamic pressure was measured in both the combustion chamber and propellants lines. With the increase in differential pressure between the propellant injection pressure and the combustion chamber pressure, the combustion instability intensity increased. In addition, the flame structure was recorded using a high-speed camera to detect CH* chemiluminescence intensity. With the change in the injection conditions in the gas-centered swirl coaxial injector, the flame structure changed.

Keywords: liquid rocket engine, flame structure, combustion instability, dynamic pressure

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Authors: Jean Paul Hategekimana, Dukuzumuremyi Yvonne, Mukeshimana Marthe, Alexandre Niyonshima

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Sweet potato (Ipomoea batatas) is a very important staple food crop in Rwanda due to its high growth and consumption in all parts of the country. The effect of seven different storage conditions on the quality and nutritional composition of the three most grown and consumed varieties of orange-fleshed sweet potato (OFSP), namely Kabode, Terimbere, and Vita, were studied over a period of six weeks at Postharvest Service and Training Center of University Rwanda, Busogo Campus. The potato stored under the following conditions (zero energy cooling chamber, ground washed sweet potato, ground unwashed sweet potato, perforated washed sweet potato, perforated unwashed sweet potato, non-perforated washed sweet potato, and non-perforated unwashed sweet potato) were assessed in this study. These storage conditions are the modifications of existing methods currently used in Rwanda for suitable local climatic conditions. Hence, 30kgs of freshly harvested OFSP for each variety were bought from farmers of Gakenke and Rulindo districts and then transported to the postharvest training and service center UR-CAVM, Busogo Campus. 2.5kg of each potato sample was selected and stored under the above-mentioned storage conditions after pretreatment. Data were collected for six weeks on percent weight loss, shrinkability and the general appearance at interval of three days. The stored samples were also analyzed for moisture, crude ash, crude fiber, and reduced sugar levels during the entire storage period. Results showed the difference among the various storage conditions. It was shown that ZECC and non-perforated sacs (in the open air) storage techniques had good potential for storage of orange flesh sweet potato for up to six weeks without considerable change in physical and nutritional parameters compared to other considered conditions and, therefore, can be recommended as more useful for OSFP at farm level and during transport and market storage.

Keywords: ZECC, orange fleshed sweet potato, perforated sacs, storage conditions

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Authors: Nissa Phloimontri

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This research explores the current physical conditions of motorcycle taxi stands located near the BTS stations in the central business district (CBD) and the comfort conditions of motorcycle taxi drivers. The criteria set up for physical stand survey and assessment are the integration of multimodal access design guidelines. After the survey, stands that share similar characteristics are classified into a series of typologies. Based on the environmental comfort model, questionnaires and in-depth interviews are conducted to evaluate the comfort levels of drivers including physical, functional, and psychological comfort. The results indicate that there are a number of motorcycle taxi stands that are not up to standard and are not conducive to the work-related activities of drivers. The study concludes by recommending public policy for integrated paratransit stops that support the multimodal transportation and seamless mobility concepts within the specific context of Bangkok as well as promote the quality of work life of motorcycle taxi drivers.

Keywords: motorcycle taxi, paratransit stops, environmental comfort, quality of work life

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Authors: Aneesh Babu, S. P. Anusha

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A dynamic signal control system combines traditional traffic lights with an array of sensors to intelligently control vehicle and pedestrian traffic. The present study focus on evaluating the performance of dynamic signal control systems for mixed traffic conditions. Data collected from four different approaches to a typical four-legged signalized intersection at Trivandrum city in the Kerala state of India is used for the study. Performance of three other dynamic signal control methods, namely (i) Non-sequential method (ii) Webster design for consecutive signal cycle using flow as input, and (iii) dynamic signal control using RFID delay as input, were evaluated. The evaluation of the dynamic signal control systems was carried out using a calibrated VISSIM microsimulation model. Python programming was used to integrate the dynamic signal control algorithm through the COM interface in VISSIM. The intersection delay obtained from different dynamic signal control methods was compared with the delay obtained from fixed signal control. Based on the study results, it was observed that the intersection delay was reduced significantly by using dynamic signal control methods. The dynamic signal control method using delay from RFID sensors resulted in a higher percentage reduction in delay and hence is a suitable choice for implementation under mixed traffic conditions. The developed dynamic signal control strategies can be implemented in ITS applications under mixed traffic conditions.

Keywords: dynamic signal control, intersection delay, mixed traffic conditions, RFID sensors

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Authors: Sayyed Yaghoub Zolfegharifar, Khairul Anuar Kassim, Hossein Khoramrooz, Khodayar Farhadiasl, Sadegh Jahan

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Iran is one of the world's seismically active countries so that it experiences many small to medium earthquakes annually and a large earthquake every ten years. Due to seism tectonic conditions and special geographical and climatic position, Iran has the potential to create numerous severe earthquakes. Therefore, seismicity studies and seismic zonation of seismic zones of the country are necessary. In this article, the effect of local site conditions on the characteristics of seismic design in Rahmormoz will be examined. After analyzing the seismic hazard for Rahmormoz through deterministic and statistical methods and preparing the necessary geotechnical models based on available data, the ground response will be analyzed for different parts of the city based on four inputs and acceleration level estimated for bedrock through the equivalent linear method and by means of Deep Soil program. Finally, through the analysis of the obtained results, the seismic profiles of the ground surface for different parts of the city will be presented.

Keywords: seismic microzonation, ground response, resonance spectrum, period, site conditions

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Authors: F. Sallem, B. Dahhou, A. Kamoun

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In this work, the main problem considered is the detection and the isolation of the actuator fault. A new formulation of the linear system is generated to obtain the conditions of the actuator fault diagnosis. The proposed method is based on the representation of the actuator as a subsystem connected with the process system in cascade manner. The designed formulation is generated to obtain the conditions of the actuator fault detection and isolation. Detectability conditions are expressed in terms of the invertibility notions. An example and a comparative analysis with the classic formulation illustrate the performances of such approach for simple actuator fault diagnosis by using the linear model of nuclear reactor.

Keywords: actuator fault, Fault detection, left invertibility, nuclear reactor, observability, parameter intervals, system inversion

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Authors: Smita Pareek, Ratna Dahiya

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The power generated by solar photovoltaic (PV) module depends on surrounding irradiance, temperature, shading conditions, and shading pattern. This paper presents a simulation of photovoltaic module using Matlab/Simulink. PV Array is also simulated by series and parallel connections of modules and their characteristics curves are given. Further PV module topology/configuration are proposed for 5.5kW inverter available in the literature. Shading of a PV array either complete or partial can have a significant impact on its power output and energy yield; therefore, the simulated model characteristics curves (I-V and P-V) are drawn for uniform shading conditions (USC) and then output power, voltage and current are calculated for variation in insolation for shading conditions. Additionally the characteristics curves are also given for a predetermined shadowing condition.

Keywords: array, series, parallel, photovoltaic, partial shading

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Authors: F. Al-Fahad, J. Chakkamalayath, A. Al-Aibani

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Conventional methods of determination of concrete strength under controlled laboratory conditions will not accurately represent the actual strength of concrete developed under site curing conditions. This difference in strength measurement will be more in the extreme environment in Kuwait as it is characterized by hot marine environment with normal temperature in summer exceeding 50°C accompanied by dry wind in desert areas and salt laden wind on marine and on shore areas. Therefore, it is required to have test methods to measure the in-place properties of concrete for quality assurance and for the development of durable concrete structures. The maturity method, which defines the strength of a given concrete mix as a function of its age and temperature history, is an approach for quality control for the production of sustainable and durable concrete structures. The unique harsh environmental conditions in Kuwait make it impractical to adopt experiences and empirical equations developed from the maturity methods in other countries. Concrete curing, especially in the early age plays an important role in developing and improving the strength of the structure. This paper investigates the use of maturity method to assess the effectiveness of three different types of curing methods on the compressive and flexural strength development of one high strength concrete mix of 60 MPa produced with silica fume. This maturity approach was used to predict accurately, the concrete compressive and flexural strength at later ages under different curing conditions. Maturity curves were developed for compressive and flexure strengths for a commonly used concrete mix in Kuwait, which was cured using three different curing conditions, including water curing, external spray coating and the use of internal curing compound during concrete mixing. It was observed that the maturity curve developed for the same mix depends on the type of curing conditions. It can be used to predict the concrete strength under different exposure and curing conditions. This study showed that concrete curing with external spray curing method cannot be recommended to use as it failed to aid concrete in reaching accepted values of strength, especially for flexural strength. Using internal curing compound lead to accepted levels of strength when compared with water cuing. Utilization of the developed maturity curves will help contactors and engineers to determine the in-place concrete strength at any time, and under different curing conditions. This will help in deciding the appropriate time to remove the formwork. The reduction in construction time and cost has positive impacts towards sustainable construction.

Keywords: curing, durability, maturity, strength

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Authors: Abdulkadir I.

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Scientists have come to terms with the fact that climate change has been and is expected to cause a significant increase in the severity and frequency of drought events. The northeast region of Nigeria is one of the most, if not the most, affected regions by drought in the country. Therefore, it is on this note that the present study applied ArcGIS and XLSTAT Software and explored drought and its trend in the northeast region of the country using the vegetation health index (VHI), Mann-Kendal, and Sen’s slope between 2001 and 2020. The study also explored the areas that remained under drought and no-drought conditions at intervals of five years for the period under review. The result of Mann-Kendal (-0.07) and Sen’s slope (-0.19) revealed that there was a decreasing trend in VHI over the period under review. The result further showed that the period between 2010 and 2015 had a minimum area of no-drought conditions of about 24%, with Gombe State accounting for the lowest percentage among the six States, about 0.9% of the total area of no-drought conditions. The result further showed the areas that were under drought conditions between 2010 and 2015 represented about 9.1%, with Borno State accounting for the highest percentage among the six States, about 2.5% of the total area under drought conditions. The masked-out areas stood at 66.8%, with Borno State accounting for the highest percentage among the six States, about 20.2% of the total area under drought conditions. Therefore, collective efforts are needed to put in place sustainable land management in the affected areas so as to mitigate the sprawl of desertification in the region.

Keywords: climate change, drought, Mann Kendal, sustainable land management, vegetation health index

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Authors: Oyenike Eludoyin

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Extreme climate conditions are deviation from the norms and are capable of causing upsets in many important environmental parameter including disruption of water balance and air temperature balance. Studies have shown that extreme climate conditions can foretell disaster in regions with inadequate early warning systems. In this paper, we combined geographical information systems, statistics and social surveys to evaluate the physiologic indices [(Dewpoint Temperature (Td), Effective Temperature Index (ETI) and Relative Strain Index (RSI)] and extreme climate conditions in different parts of southwest Nigeria. This was with the view to assessing the nature and the impact of the conditions on the people and their coping strategies. The results indicate that minimum, mean and maximum temperatures were higher in 1960-1990 than 1991-2013 periods at most areas, and more than 80% of the people adapt to thermal stress by changing wear type or cloth, installing air conditioner and fan at home and/or work place and sleeping outside at certain period of the night and day. With respect to livelihoods, about 52% of the interviewed farmers indicated that too early rainfall, late rainfall, prolonged dryness after an initial rainfall, excessive rainfall and windstorms caused low crop yields. Main (76%) coping strategies were changing of planting dates, diversification of crops, and practices of mulching and intercropping. Government or institutional support was less than 20%.

Keywords: coping strategies, extreme climate, livelihoods, physiologic comfort

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Authors: Mustafa Sertçelik, Hacali Necefoğlu, Turan Çalban, Soner Kuşlu

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In this study, Chevreul’s salt was dissolved in ammonium chloride solutions. All experiments were performed in a batch reactor. The obtained results were optimized. Parameters used in the experiments were the reaction temperature, the ammonium chloride concentration, the reaction time and the solid-to-liquid ratio. The optimum conditions were determined by 2⁴ factorial experimental design method. The best values of four parameters were determined as based on the experiment results. After the evaluation of experiment results, all parameters were found as effective in experiment conditions selected. The optimum conditions on the maximum Chevreul’s salt dissolution were the ammonium chloride concentration 4.5 M, the reaction time 13.2 min., the reaction temperature 25 ^oC, and the solid-to-liquid ratio 9/80 g.mL^-1. The best dissolution yield in these conditions was 96.20%.

Keywords: Chevreul's salt, factorial experimental design method, ammonium chloride, dissolution, optimization

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Authors: Laurie Prange-Martin, Romeo Turcan, Norman Fraser

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The aim of this study is to identify the conditions required and describe the process of emergence for a new economic sector created from new or established businesses. A systematic literature review of English-language studies published from 1983 to 2016 was conducted using the following databases: ABI/INFORM Complete; Business Source Premiere; Google Scholar; Scopus; and Web of Science. The two main terms of business sector and emergence were used in the systematic literature search, along with another seventeen synonyms for each these main terms. From the search results, 65 publications met the requirements of an empirical study discussing and reporting the conditions of new sector emergence. A meta-analysis of the literature examined suggest that there are six favourable conditions and five key individuals or groups required for new sector emergence. In addition, the results from the meta-analysis showed that there are eighteen theories used in the literature to explain the phenomenon of new sector emergence, which can be grouped in three study disciplines. With such diversity in theoretical frameworks used in the 65 empirical studies, the authors of this paper propose the development of a new theory of sector emergence.

Keywords: economic geography, new sector emergence, economic diversification, regional economies

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Authors: C. Rattanakawin, S. Vasailor

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Acid leaching of flotation concentrate of oxide copper ore containing mainly of malachite was performed in a standard agitation tank with various parameters. The effects of solid to liquid ratio, sulfuric acid concentration, agitation speed, leaching temperature and time were examined to get proper conditions. The best conditions are 1:8 solid to liquid ratio, 10% concentration by weight, 250 rev/min, 30 ^oC and 5-min leaching time in respect. About 20% Cu grade assayed by atomic absorption technique with 98% copper recovery was obtained from these combined optimum conditions. Dissolution kinetics of the concentrate was approximated as a logarithmic function. As a result, the first-order reaction rate is suggested from this leaching study.

Keywords: agitation leaching, dissolution kinetics, flotation concentrate, oxide copper ore, sulfuric acid

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Authors: Peter Parkinson

Abstract:

The research investigates the effects of temperature, humidity, wind speed, and fabric composition on the drying times of blood and assesses the degree of blood transfer that can occur during the drying process. An assortment of fabrics, of different composition and thicknesses, were collected and stained using two blood volumes and exposed to varying environmental conditions. The conclusion reached was that temperature, humidity, wind speed, and fabric thickness do have an effect on drying times. An increase in temperature and wind speed results in a decrease in drying times while an increase in fabric thickness and humidity extended the drying times of blood under similar conditions. Transfer experimentation utilized three donor fabrics, 100% white cotton, 100% acrylic, and 100% cotton denim, which were bloodstained using two blood volumes. The fabrics were subjected to both full and low/light force contact from the donor fabrics onto the recipient fabric, under different environmental conditions. Transfer times onto the 100% white cotton (recipient fabric) from all donor fabrics were shorter than the drying times observed. The intensities of the bloodstains decreased from high to low with time during the drying process. The degree of transfer at high, medium, and low intensities varied significantly between different materials and is dependent on the environmental conditions, fabric compositions, blood volumes, the type of contact (full or light force), and the drying times observed for the respective donor fabrics. These factors should be considered collectively and conservatively when assessing the time frame of secondary transfer in casework.

Keywords: blood, drying time, blood stain transfer, different environmental conditions, fabrics

Procedia PDF Downloads 130

Authors: Buket Boz, Alvaro Diez

Abstract:

Waste heat recovery by means of Organic Rankine Cycle is a promising technology for the recovery of engine exhaust heat. However, it is complex to find out the optimum cycle conditions with appropriate working fluids to match exhaust gas waste heat due to its high temperature. Hence, this paper focuses on comparing sub-critical and supercritical ORC conditions with eight working fluids on a combined diesel engine-ORC system. The model employs two ORC designs, Regenerative-ORC and Pre-Heating-Regenerative-ORC respectively. The thermodynamic calculations rely on the first and second law of thermodynamics, thermal efficiency and exergy destruction factors are the fundamental parameters evaluated. Additionally, in this study, environmental and safety, GWP (Global Warming Potential) and ODP (Ozone Depletion Potential), characteristic of the refrigerants are taken into consideration as evaluation criteria to define the optimal ORC configuration and conditions. Consequently, the studys outcomes reveal that supercritical ORCs with alkane and siloxane are more suitable for high temperature exhaust waste heat recovery in contrast to sub-critical conditions.

Keywords: internal combustion engine, organic Rankine cycle, waste heat recovery, working fluids

Procedia PDF Downloads 175