Search results for: strain rate effect
21556 Dynamic Thermomechanical Behavior of Adhesively Bonded Composite Joints
Authors: Sonia Sassi, Mostapha Tarfaoui, Hamza Benyahia
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Composite materials are increasingly being used as a substitute for metallic materials in many technological applications like aeronautics, aerospace, marine and civil engineering applications. For composite materials, the thermomechanical response evolves with the strain rate. The energy balance equation for anisotropic, elastic materials includes heat source terms that govern the conversion of some of the kinetic work into heat. The remainder contributes to the stored energy creating the damage process in the composite material. In this paper, we investigate the bulk thermomechanical behavior of adhesively-bonded composite assemblies to quantitatively asses the temperature rise which accompanies adiabatic deformations. In particular, adhesively bonded joints in glass/vinylester composite material are subjected to in-plane dynamic loads under a range of strain rates. Dynamic thermomechanical behavior of this material is investigated using compression Split Hopkinson Pressure Bars (SHPB) coupled with a high speed infrared camera and a high speed camera to measure in real time the dynamic behavior, the damage kinetic and the temperature variation in the material. The interest of using high speed IR camera is in order to view in real time the evolution of heat dissipation in the material when damage occurs. But, this technique does not produce thermal values in correlation with the stress-strain curves of composite material because of its high time response in comparison with the dynamic test time. For this reason, the authors revisit the application of specific thermocouples placed on the surface of the material to ensure the real thermal measurements under dynamic loading using small thermocouples. Experiments with dynamically loaded material show that the thermocouples record temperatures values with a short typical rise time as a result of the conversion of kinetic work into heat during compression test. This results show that small thermocouples can be used to provide an important complement to other noncontact techniques such as the high speed infrared camera. Significant temperature rise was observed in in-plane compression tests especially under high strain rates. During the tests, it has been noticed that sudden temperature rise occur when macroscopic damage occur. This rise in temperature is linked to the rate of damage. The more serve the damage is, a higher localized temperature is detected. This shows the strong relationship between the occurrence of damage and induced heat dissipation. For the case of the in plane tests, the damage takes place more abruptly as the strain rate is increased. The difference observed in the obtained thermomechanical response in plane compression is explained only by the difference in the damage process being active during the compression tests. In this study, we highlighted the dependence of the thermomechanical response on the strain rate of bonded specimens. The effect of heat dissipation of this material cannot hence be ignored and should be taken into account when defining damage models during impact loading.Keywords: adhesively-bonded composite joints, damage, dynamic compression tests, energy balance, heat dissipation, SHPB, thermomechanical behavior
Procedia PDF Downloads 20921555 Induction of Adaptive Response in Yeast Cells under Influence of Extremely High Frequency Electromagnetic Field
Authors: Sergei Voychuk
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Introduction: Adaptive response (AR) is a manifestation of radiation hormesis, which deal with the radiation resistance that may be increased with the pretreatment with small doses of radiation. In the current study, we evaluated the potency of radiofrequency EMF to induce the AR mechanisms and to increase a resistance to UV light. Methods: Saccharomyces cerevisiae yeast strains, which were created to study induction of mutagenesis and recombination, were used in the study. The strains have mutations in rad2 and rad54 genes, responsible for DNA repair: nucleotide excision repair (PG-61), postreplication repair (PG-80) and mitotic (crossover) recombination (T2). An induction of mutation and recombination are revealed due to the formation of red colonies on agar plates. The PG-61 and T2 are UV sensitive strains, while PG-80 is sensitive to ionizing radiation. Extremely high frequency electromagnetic field (EHF-EMF) was used. The irradiation was performed in floating mode and frequency changed during exposure from 57 GHz to 62 GHz. The power of irradiation was 100 mkW, and duration of exposure was 10 and 30 min. Treatment was performed at RT and then cells were stored at 28° C during 1 h without any exposure but after that they were treated with UV light (254nm) for 20 sec (strain T2) and 120 sec (strain PG-61 and PG-80). Cell viability and quantity of red colonies were determined after 5 days of cultivation on agar plates. Results: It was determined that EHF-EMF caused 10-20% decrease of viability of T2 and PG-61 strains, while UV showed twice stronger effect (30-70%). EHF-EMF pretreatment increased T2 resistance to UV, and decreased it in PG-61. The PG-80 strain was insensitive to EHF-EMF and no AR effect was determined for this strain. It was not marked any induction of red colonies formation in T2 and PG-80 strain after EHF or UV exposure. The quantity of red colonies was 2 times more in PG-61 strain after EHF-EMF treatment and at least 300 times more after UV exposure. The pretreatment of PG-61 with EHF-EMF caused at least twice increase of viability and consequent decrease of amount of red colonies. Conclusion: EHF-EMF may induce AR in yeast cells and increase their viability under UV treatment.Keywords: Saccharomyces cerevisiae, EHF-EMF, UV light, adaptive response
Procedia PDF Downloads 31621554 Experimental and Numerical Investigation on Deformation Behaviour of Single Crystal Copper
Authors: Suman Paik, P. V. Durgaprasad, Bijan K. Dutta
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A study combining experimental and numerical investigation on the deformation behaviour of single crystals of copper is presented in this paper. Cylindrical samples were cut in specific orientations from high purity copper single crystal and subjected to uniaxial compression loading at quasi-static strain rate. The stress-strain curves along two different crystallographic orientations were then extracted. In order to study and compare the deformation responses, a single crystal plasticity model incorporating non-Schmid effects was developed assuming cross-slip plays an important role in orientation of the material. By making use of crystal plasticity finite element method, the model was applied to investigate the orientation dependence of the stress-strain behaviour of two crystallographic orientations. Finally, details of slip activities of deformed crystals were investigated by linking the orientation of slip lines with the theoretical traces of possible crystallographic planes. The experimentally determined active slip modes were matched with those determined by simulations.Keywords: crystal plasticity, modelling, non-Schmid effects, finite elements, finite strain
Procedia PDF Downloads 20821553 Correlation between Copper Uptake and Decrease of Copper (Hypocupremia) in Burn Patients-Infected Pseudomonas aeruginosa
Authors: Khaled M. Khleifat
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Pseudomonas aeruginosa was isolated from infected burn patients and characterized by standard biochemical tests. The in vitro copper uptake was compared between this isolated pathogenic strain and two non-pathogenic control strains of Gram-positive bacteria Bacillusthuringiensis strain Israelisas well as Gram-negative bacteria Enterobacter aerogenes. Maximum copper uptake of 470 ppm/g biomass was obtained by P. aeruginosa strain, while the control strains B. thuringiensis and Enterobacter aerogenes had copper uptake of 350 and 383 ppm/g biomass, respectively. However, the lowest copper uptake (60 ppm/g biomass) was observed with another control the saprophytic strain Pseudomonas (Shewanella) putrefaciens. A further investigation regarding the effect of copper toxicity on bacterial growth, gave an MIC score of 600 ppm for P. aeruginosa strain compared to 460 and 300 ppm for the two Gram positive and Gram negative control strains, respectively. In tandem with these in vitro findings, blood analysis on burn patients infected with P. aeruginosa has indicated a selective decrease of copper (hypocupremia) and ceruloplasmin plasma levels. The iron metabolism was also affected by this copper deprivation leading to a similar decrease in plasma levels of PCV, iron, total iron-binding capacity, and transferrin. All these hematological changes were significantly different (P < 0.05) from the matched group of non-infected burn patients. The observed hypocupremia in infected burn patients was attributed to demanding scavenger ability by P. aeruginosa strain for the copper of plasma.Keywords: Pseudomonas aeruginosa, hypocupremia, correlation, PCV
Procedia PDF Downloads 30521552 Sensitivity Improvement of Optical Ring Resonator for Strain Analysis with the Direction of Strain Recognition Possibility
Authors: Tayebeh Sahraeibelverdi, Ahmad Shirazi Hadi Veladi, Mazdak Radmalekshah
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Optical sensors became attractive due to preciseness, low power consumption, and intrinsic electromagnetic interference-free characteristic. Among the waveguide optical sensors, cavity-based ones attended for the high Q-factor. Micro ring resonators as a potential platform have been investigated for various applications as biosensors to pressure sensors thanks to their sensitive ring structure responding to any small change in the refractive index. Furthermore, these small micron size structures can come in an array, bringing the opportunity to have any of the resonance in a specific wavelength and be addressed in this way. Another exciting application is applying a strain to the ring and making them an optical strain gauge where the traditional ones are based on the piezoelectric material. Making them in arrays needs electrical wiring and about fifty times bigger in size. Any physical element that impacts the waveguide cross-section, Waveguide elastic-optic property change, or ring circumference can play a role. In comparison, ring size change has a larger effect than others. Here an engineered ring structure is investigated to study the strain effect on the ring resonance wavelength shift and its potential for more sensitive strain devices. At the same time, these devices can measure any strain by mounting on the surface of interest. The idea is to change the" O" shape ring to a "C" shape ring with a small opening starting from 2π/360 or one degree. We used the Mode solution of Lumbrical software to investigate the effect of changing the ring's opening and the shift induced by applied strain. The designed ring radius is a three Micron silicon on isolator ring which can be fabricated by standard complementary metal-oxide-semiconductor (CMOS) micromachining. The measured wavelength shifts from1-degree opening of the ring to a 6-degree opening have been investigated. Opening the ring for 1-degree affects the ring's quality factor from 3000 to 300, showing an order of magnitude Q-factor reduction. Assuming a strain making the ring-opening from 1 degree to 6 degrees, our simulation results showing negligible Q-factor reduction from 300 to 280. A ring resonator quality factor can reach up to 108 where an order of magnitude reduction is negligible. The resonance wavelength shift showed a blue shift and was obtained to be 1581, 1579,1578,1575nm for 1-, 2-, 4- and 6-degree ring-opening, respectively. This design can find the direction of the strain-induced by applying the opening on different parts of the ring. Moreover, by addressing the specified wavelength, we can precisely find the direction. We can open a significant opportunity to find cracks and any surface mechanical property very specifically and precisely. This idea can be implemented on polymer ring resonators while they can come with a flexible substrate and can be very sensitive to any strain making the two ends of the ring in the slit part come closer or further.Keywords: optical ring resonator, strain gauge, strain sensor, surface mechanical property analysis
Procedia PDF Downloads 11921551 The Correlation of Economic Variables on Domestic Investment
Authors: Amirreza Attarzadeh
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This paper aims to investigate the relationship between economic variables, e.g., inflation rate, interest rate, trade openness and the growth rate of GDP, with domestic investment. The present study also draws on conceptual economy related theories to verify the negative effect of interest rates on domestic investment. However, trade openness and growth rate had a positive correlation, and the inflation rate may have a positive or negative impact on domestic investment.Keywords: inflation rate, growth rate of GDP, interest rate and trade openness, domestic investment
Procedia PDF Downloads 40121550 Measurements of Recovery Stress and Recovery Strain of Ni-Based Shape Memory Alloys
Authors: W. J. Kim
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The behaviors of the recovery stress and strain of an ultrafine-grained Ni-50.2 at.% Ti alloy prepared by high-ratio differential speed rolling (HRDSR) were examined by a specially designed tensile-testing set up, and the factors that influence the recovery stress and strain were studied. After HRDSR, both the recovery stress and strain were enhanced compared to the initial condition. The constitutive equation showing that the maximum recovery stress is a sole function of the recovery strain was developed based on the experimental data. The recovery strain increased as the yield stress increased. The maximum recovery stress increased with an increase in yield stress. The residual recovery stress was affected by the yield stress as well as the austenite-to-martensite transformation temperature. As the yield stress increased and as the martensitic transformation temperature decreased, the residual recovery stress increased.Keywords: high-ratio differential speed rolling, tensile testing, severe plastic deformation, shape memory alloys
Procedia PDF Downloads 35921549 Tunable Optoelectronic Properties of WS₂ by Local Strain Engineering and Folding
Authors: Ahmed Raza Khan
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Local-strain engineering is an exciting approach to tune the optoelectronic properties of materials and enhance the performance of devices. Two dimensional (2D) materials such as 2D transition metal dichalcogenides (TMDCs) are particularly well-suited for this purpose because they have high flexibility and can withstand high deformations before rupture. Wrinkles on thick TMDC layers have been reported to show the interesting photoluminescence enhancement due to bandgap modulation and funneling effect. However, the wrinkles in ultrathin TMDCs have not been investigated, because the wrinkles can easily fall down to form folds in these ultrathin layers of TMDCs. Here, we have achieved both wrinkle and fold nano-structures simultaneously on 1-3L WS₂ using a new fabrication technique. The comparable layer dependent reduction in surface potential is observed for both folded layers and corresponding perfect pack layers due to the dominant interlayer screening effect. The strains produced from the wrinkle nanostructures considerably vary semi conductive junction properties. Thermo-ionic modelling suggests that the strained (1.6%) wrinkles can lower the Schottky barrier height (SBH) by 20%. The photo-generated carriers would further significantly lower the SBH. These results present an important advance towards controlling the optoelectronic properties of atomically thin WS₂ using strain engineering, with important implications for practical device applications.Keywords: strain engineering, folding, WS₂, Kelvin probe force microscopy, KPFM, surface potential, photo current, layer dependence
Procedia PDF Downloads 10321548 The Effect of Heart Rate and Valence of Emotions on Perceived Intensity of Emotion
Authors: Madeleine Nicole G. Bernardo, Katrina T. Feliciano, Marcelo Nonato A. Nacionales III, Diane Frances M. Peralta, Denise Nicole V. Profeta
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This study aims to find out if heart rate variability and valence of emotion have an effect on perceived intensity of emotion. Psychology undergraduates (N = 60) from the University of the Philippines Diliman were shown 10 photographs from the Japanese Female Facial Expression (JAFFE) Database, along with a corresponding questionnaire with a Likert scale on perceived intensity of emotion. In this 3 x 2 mixed subjects factorial design, each group was either made to do a simple exercise prior to answering the questionnaire in order to increase the heart rate, listen to a heart rate of 120 bpm, or colour a drawing to keep the heart rate stable. After doing the activity, the participants then answered the questionnaire, providing a rating of the faces according to the participants’ perceived emotional intensity on the photographs. The photographs presented were either of positive or negative emotional valence. The results of the experiment showed that neither an induced fast heart rate or perceived fast heart rate had any significant effect on the participants’ perceived intensity of emotion. There was also no interaction effect of heart rate variability and valence of emotion. The insignificance of results was explained by the Philippines’ high context culture, accompanied by the prevalence of both intensely valenced positive and negative emotions in Philippine society. Insignificance in the effects were also attributed to the Cannon-Bard theory, Schachter-Singer theory and various methodological limitations.Keywords: heart rate variability, perceived intensity of emotion, Philippines , valence of emotion
Procedia PDF Downloads 24121547 Association between Copper Uptake and Decrease of Copper (hypocupremia) in Burn Patients-Infected Pseudomonas aeruginosa
Authors: Khaled Khleifat, Muayyad Abboud, Amjad Khleifat, Humodi Saeed
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In this study, Pseudomonas aeruginosa was isolated from infected burn patients and characterized by standard biochemical tests. The in vitro copper uptake was compared between this isolated pathogenic strain and two non-pathogenic control strains of Gram positive bacteria Bacillusthuringiensis strain Israelisas well as Gram negative bacteria Enterobacter aerogenes. Maximum copper uptake of 470 ppm/g biomass was obtained by P. aeruginosa strain, while the control strains B. thuringiensis andEnterobacter aerogenes had copper uptake of 350 and 383 ppm/g biomass, respectively. However, the lowest copper uptake (60 ppm/g biomass) was observed with another control the saprophytic strain Pseudomonas (Shewanella) putrefaciens. A further investigation regarding the effect of copper toxicity on bacterial growth, gave an MIC score of 600 ppm for P. aeruginosa strain compared to 460 and 300 ppm for the two Gram positive and Gram negative control strains, respectively. In tandem with these in vitro findings, blood analysis on burn patients infected with P. aeruginosa has indicated a selective decrease of copper (hypocupremia) and ceruloplasmin plasma levels. The iron metabolism was also affected by this copper deprivation leading to a similar decrease in plasma levels of PCV, iron, total iron binding capacity, and transferrin. All these hematological changes were significantly different (P < 0.05) from the matched group of non-infected burn patients. The observed hypocupremia in infected burn patients was attributed to demanding scavenger ability by P. aeruginosa strain for the copper of plasma.Keywords: pseudomonas, Cu uptake, burn patients, biosorption
Procedia PDF Downloads 38721546 Ethyl Methane Sulfonate-Induced Dunaliella salina KU11 Mutants Affected for Growth Rate, Cell Accumulation and Biomass
Authors: Vongsathorn Ngampuak, Yutachai Chookaew, Wipawee Dejtisakdi
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Dunaliella salina has great potential as a system for generating commercially valuable products, including beta-carotene, pharmaceuticals, and biofuels. Our goal is to improve this potential by enhancing growth rate and other properties of D. salina under optimal growth conditions. We used ethyl methane sulfonate (EMS) to generate random mutants in D. salina KU11, a strain classified in Thailand. In a preliminary experiment, we first treated D. salina cells with 0%, 0.8%, 1.0%, 1.2%, 1.44% and 1.66% EMS to generate a killing curve. After that, we randomly picked 30 candidates from approximately 300 isolated survivor colonies from the 1.44% EMS treatment (which permitted 30% survival) as an initial test of the mutant screen. Among the 30 survivor lines, we found that 2 strains (mutant #17 and #24) had significantly improved growth rates and cell number accumulation at stationary phase approximately up to 1.8 and 1.45 fold, respectively, 2 strains (mutant #6 and #23) had significantly decreased growth rates and cell number accumulation at stationary phase approximately down to 1.4 and 1.35 fold, respectively, while 26 of 30 lines had similar growth rates compared with the wild type control. We also analyzed cell size for each strain and found there was no significant difference comparing all mutants with the wild type. In addition, mutant #24 had shown an increase of biomass accumulation approximately 1.65 fold compared with the wild type strain on day 5 that was entering early stationary phase. From these preliminary results, it could be feasible to identify D. salina mutants with significant improved growth rate, cell accumulation and biomass production compared to the wild type for the further study; this makes it possible to improve this microorganism as a platform for biotechnology application.Keywords: Dunaliella salina, ethyl methyl sulfonate, growth rate, biomass
Procedia PDF Downloads 23621545 Modeling the Effect of Thermal Gradation on Steady-State Creep Behavior of Isotropic Rotating Disc Made of Functionally Graded Material
Authors: Tania Bose, Minto Rattan, Neeraj Chamoli
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In this paper, an attempt has been made to study the effect of thermal gradation on the steady-state creep behavior of rotating isotropic disc made of functionally graded material using threshold stress based Sherby’s creep law. The composite discs made of aluminum matrix reinforced with silicon carbide particulate have been taken for analysis. The stress and strain rate distributions have been calculated for the discs rotating at elevated temperatures having thermal gradation. The material parameters of creep vary radially and have been estimated by regression fit of the available experimental data. Investigations for discs made up of linearly increasing particle content operating under linearly decreasing temperature from inner to outer radii have been done using von Mises’ yield criterion. The results are displayed and compared graphically in designer friendly format for the above said disc profile with the disc made of particle reinforced composite operating under uniform temperature profile. It is observed that radial and tangential stresses show minor variation and the strain rates vary significantly in the presence of thermal gradation as compared to disc having uniform temperature.Keywords: creep, isotropic, steady-state, thermal gradation
Procedia PDF Downloads 23121544 Mechanisms Involved in Biological Control of Fusarium Wilt
Authors: Bensaid Fatiha
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The objective of our present work is the description of the antagonistic capacities of one strain of Pseudomonas fluorescens and the nonpathogenic fungic isolate Fusarium oxysporum against phytopathogenic agent Fusarium oxysporum F. Sp. lycopersici. This work has been achieved in two main parts: the first is interested on the in vitro antagonistic activities; the second was interested to study the soil receptiveness of fusarium wilt tomato. The use of strain of fluorescent Pseudomonas and a non-pathogenic strain of F. oxysporum in the different antagonism tests, has allowed assuring a certain bio-protection from the plants of tomatoes opposite to F. oxysporum F. Sp. lycopersici, agent of a wilt of tomato. These antagonistic have shown a substantial in vitro antagonistic activity on the three mediums (KB, PDA, KB+PDA) against F. oxysporum F. Sp. lycopersici, by inhibiting its growth mycelium with rate of inhibition going until 80 % with non-pathogen of Fusarium oxysporum and 60 % with strain of fluorescens Pseudomonas. Soil microbial balance, between the antagonistic population and that of pathogenic, can be modulated through microbiological variations or abiotic additives influencing directly or indirectly the metabolic behavior microbial. In this experiment, addition of glucose or EDTA, could increase or decrease the resistance of soil by activation of pathogenic or antagonists, as a result of modification and modulation in their metabolic activities.Keywords: fluorescents, nonpathogenic, fusarium oxysporum, fusarium wilt, antagonism, biological control, soil receptivity
Procedia PDF Downloads 45121543 Selection of Pichia kudriavzevii Strain for the Production of Single-Cell Protein from Cassava Processing Waste
Authors: Phakamas Rachamontree, Theerawut Phusantisampan, Natthakorn Woravutthikul, Peerapong Pornwongthong, Malinee Sriariyanun
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A total of 115 yeast strains isolated from local cassava processing wastes were measured for crude protein content. Among these strains, the strain MSY-2 possessed the highest protein concentration (>3.5 mg protein/mL). By using molecular identification tools, it was identified to be a strain of Pichia kudriavzevii based on similarity of D1/D2 domain of 26S rDNA region. In this study, to optimize the protein production by MSY-2 strain, Response Surface Methodology (RSM) was applied. The tested parameters were the carbon content, nitrogen content, and incubation time. Here, the value of regression coefficient (R2) = 0.7194 could be explained by the model, which is high to support the significance of the model. Under the optimal condition, the protein content was produced up to 3.77 g per L of the culture and MSY-2 strain contain 66.8 g protein per 100 g of cell dry weight. These results revealed the plausibility of applying the novel strain of yeast in single-cell protein production.Keywords: single cell protein, response surface methodology, yeast, cassava processing waste
Procedia PDF Downloads 39521542 A Meso Macro Model Prediction of Laminated Composite Damage Elastic Behaviour
Authors: A. Hocine, A. Ghouaoula, S. M. Medjdoub, M. Cherifi
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The present paper proposed a meso–macro model describing the mechanical behaviour composite laminates of staking sequence [+θ/-θ]s under tensil loading. The behaviour of a layer is ex-pressed through elasticity coupled to damage. The elastic strain is due to the elasticity of the layer and can be modeled by using the classical laminate theory, and the laminate is considered as an orthotropic material. This means that no coupling effect between strain and curvature is considered. In the present work, the damage is associated to cracking of the matrix and parallel to the fibers and it being taken into account by the changes in the stiffness of the layers. The anisotropic damage is completely described by a single scalar variable and its evolution law is specified from the principle of maximum dissipation. The stress/strain relationship is investigated in plane stress loading.Keywords: damage, behavior modeling, meso-macro model, composite laminate, membrane loading
Procedia PDF Downloads 47021541 The Fiscal-Monetary Policy and Economic Growth in Algeria: VECM Approach
Authors: K. Bokreta, D. Benanaya
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The objective of this study is to examine the relative effectiveness of monetary and fiscal policy in Algeria using the econometric modelling techniques of cointegration and vector error correction modelling to analyse and draw policy inferences. The chosen variables of fiscal policy are government expenditure and net taxes on products, while the effect of monetary policy is presented by the inflation rate and the official exchange rate. From the results, we find that in the long-run, the impact of government expenditures is positive, while the effect of taxes is negative on growth. Additionally, we find that the inflation rate is found to have little effect on GDP per capita but the impact of the exchange rate is insignificant. We conclude that fiscal policy is more powerful then monetary policy in promoting economic growth in Algeria.Keywords: economic growth, monetary policy, fiscal policy, VECM
Procedia PDF Downloads 30421540 Reliability Based Optimal Design of Laterally Loaded Pile with Limited Residual Strain Energy Capacity
Authors: M. Movahedi Rad
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In this study, a general approach to the reliability based limit analysis of laterally loaded piles is presented. In engineering practice, the uncertainties play a very important role. The aim of this study is to evaluate the lateral load capacity of free head and fixed-head long pile when the plastic limit analysis is considered. In addition to the plastic limit analysis to control the plastic behaviour of the structure, uncertain bound on the complementary strain energy of the residual forces is also applied. This bound has a significant effect for the load parameter. The solution to reliability-based problems is obtained by a computer program which is governed by the reliability index calculation.Keywords: reliability, laterally loaded pile, residual strain energy, probability, limit analysis
Procedia PDF Downloads 34521539 The Effect of Deficit Financing on Macro-Economic Variables in Nigeria (1970-2013)
Authors: Ezeoke Callistus Obiora, Ezeoke Nneka Angela
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The study investigated the effect of deficit financing on macroeconomic variables in Nigeria. The specific objectives included to find out the relationship between deficit financing and GDP, interest rate, inflation rate, money supply, exchange rate and private investment respectively on a time series covering a period of 44 years (1970 – 2013). The Ordinary Least Square multiple regression produced statistics for the coefficient of determination (R2), F-test, t-test used for the interpretation of the study. The findings revealed that Deficit financing has significant positive effect on GDP and exchange rate. Again, deficit financing has a positive and insignificant relationship inflation, money supply and investment. Only interest rate recorded negative yet insignificant relationship with deficit financing. The implications of the findings are that deficit financing can be a veritable tool for boosting economic development in Nigeria, but the influential positively rising exchange rate implies that deficit financing devalues the Naira exchange rate to other currencies indicating that deficit financing can affect Nigerians competitive advantage at the world market. Thus, the study concludes that deficit financing has not encouraged economic growth in Nigeria.Keywords: deficit financing, money supply, exchange rate, inflation, GDP, investment, Nigeria
Procedia PDF Downloads 47221538 Engine Thrust Estimation by Strain Gauging of Engine Mount Assembly
Authors: Rohit Vashistha, Amit Kumar Gupta, G. P. Ravishankar, Mahesh P. Padwale
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Accurate thrust measurement is required for aircraft during takeoff and after ski-jump. In a developmental aircraft, takeoff from ship is extremely critical and thrust produced by the engine should be known to the pilot before takeoff so that if thrust produced is not sufficient then take-off can be aborted and accident can be avoided. After ski-jump, thrust produced by engine is required because the horizontal speed of aircraft is less than the normal takeoff speed. Engine should be able to produce enough thrust to provide nominal horizontal takeoff speed to the airframe within prescribed time limit. The contemporary low bypass gas turbine engines generally have three mounts where the two side mounts transfer the engine thrust to the airframe. The third mount only takes the weight component. It does not take any thrust component. In the present method of thrust estimation, the strain gauging of the two side mounts is carried out. The strain produced at various power settings is used to estimate the thrust produced by the engine. The quarter Wheatstone bridge is used to acquire the strain data. The engine mount assembly is subjected to Universal Test Machine for determination of equivalent elasticity of assembly. This elasticity value is used in the analytical approach for estimation of engine thrust. The estimated thrust is compared with the test bed load cell thrust data. The experimental strain data is also compared with strain data obtained from FEM analysis. Experimental setup: The strain gauge is mounted on the tapered portion of the engine mount sleeve. Two strain gauges are mounted on diametrically opposite locations. Both of the strain gauges on the sleeve were in the horizontal plane. In this way, these strain gauges were not taking any strain due to the weight of the engine (except negligible strain due to material's poison's ratio) or the hoop's stress. Only the third mount strain gauge will show strain when engine is not running i.e. strain due to weight of engine. When engine starts running, all the load will be taken by the side mounts. The strain gauge on the forward side of the sleeve was showing a compressive strain and the strain gauge on the rear side of the sleeve shows a tensile strain. Results and conclusion: the analytical calculation shows that the hoop stresses dominate the bending stress. The estimated thrust by strain gauge shows good accuracy at higher power setting as compared to lower power setting. The accuracy of estimated thrust at max power setting is 99.7% whereas at lower power setting is 78%.Keywords: engine mounts, finite elements analysis, strain gauge, stress
Procedia PDF Downloads 47321537 To Study the Effect of Optic Fibre Laser Cladding of Cast Iron with Silicon Carbide on Wear Rate
Authors: Kshitij Sawke, Pradnyavant Kamble, Shrikant Patil
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The study investigates the effect on wear rate of laser clad of cast iron with silicon carbide. Metal components fail their desired use because they wear, which causes them to lose their functionality. The laser has been used as a heating source to create a melt pool over the surface of cast iron, and then a layer of hard silicon carbide is deposited. Various combinations of power and feed rate of laser have experimented. A suitable range of laser processing parameters was identified. Wear resistance and wear rate properties were evaluated and the result showed that the wear resistance of the laser treated samples was exceptional to that of the untreated samples.Keywords: laser clad, processing parameters, wear rate, wear resistance
Procedia PDF Downloads 25021536 Static Strain Aging in Ferritic and Austenitic Stainless Steels
Authors: Songul Kurucay, Mustafa Acarer, Harun Sepet
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Static strain aging occurs when metallic materials are subjected to deformation and then heat treated at low temperatures such as 150-200oC. Static strain aging occurs in BCC metals and results and increasing in yield and tensile strength and decreasing ductility due to carbon and/or nitrogen atoms locking dislocations. The locked dislocations increase yield and tensile strength. In this study, static strain aging behaviors of ferritic and austenitic stainless steel were investigated. Ferritic stainless steel was prestained at %5, %10 and %15 and then aged at 150oC and 200oC for 30 minutes. Austenitic stainless steel was also prestained at %20 and %30 and then heat treated at 200, 400 and 600oC for 30 minutes. After the heat treatment, the tensile test was performed to determine the effect of prestain and heat treatment on the steels. Hardness measurements and detailed microstructure characterization were also done. While AISI 430 ferritic stainless steel sample which was prestained at 15% and aged at 200oC, showed the highest increasing in the yield strength, AISI 304 austenitic stainless steel which was prestained at 30% and aged at 600oC, has the highest yield strength. Microstructure photographs also support the mechanical test results.Keywords: austenitic stainless steel, ferritic stainless steel, static strain aging, tensile strength
Procedia PDF Downloads 43621535 An Experimental Investigation in Effect of Confining Stress and Matric Suction on the Mechanical Behavior of Sand with Different Fine Content
Authors: S. Asreazad
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This paper presents the results that the soil volumetric strain and shear strength are closely related to the confining stress and initial matric suction under constant water content testing on the specimens of unsaturated sand with clay and silt fines contents. The silty sand specimens reached their peak strength after a very small axial strain followed by a post-peak softening towards an ultimate value. The post-peak drop in stress increased by an increment of the suction, while there is no peak strength for clayey sand specimens. The clayey sand shows compressibility and possesses ductile stress-strain behaviour. Shear strength increased nonlinearly with respect to matric suction for both soil types. When suction exceeds a certain range, the effect of suction on shear strength increment weakens gradually. Under the same confining stress, the dilatant tendencies in the silty sand increased under lower values of suction and decreased for higher suction values under the same confining stress. However, the amount of contraction increased with increasing initial suction for clayey sand specimens.Keywords: unsaturated soils, silty sand, clayey sand, triaxial test
Procedia PDF Downloads 32621534 Preliminary Evaluation of the Probiotic Potential of Leuconostoc mesonteroides Strain Isolated from Goat's Milk
Authors: Benyoucef Amel, Benmechernene Zineb, Kihal Mebrouk
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One strain (V1) of Leuconostoc mesonteroides was isolated from goat’s milk collected from El Bayadh which is located in the west of Algeria and was characterized by phenotypic and biochemical methods. This strain was tested for their antimicrobial activity against indicator bacteria (Staphylococcus aureus ATCC 43300, Listeria innocua ATCC 33090, Listeria ivanovii ATCC 19119) and was evaluated for certain properties relevant to probiotic including acid resistance (pH 2 ; 3and 4), bile tolerance at 0.5%, 1% and 2%, pepsin resistance 3mg/ml at pH 2 and 3, hemolytic activity and antibiotics sensitivity. Our results revealed the strain V1 showed antagonistic activity against Staphylococcus aureus, Listeria innocua and Listeria ivanovii, due to a production of proteinous nature substances. The strain was resistant to pH 3 and 4, bile salts at 0.5%, 1% and 2% and pepsin at pH 3; and was γ-hemolytic and susceptible to four antibiotics: Chloramphenicol, pristinamycin, Clindamycin and Lincomycin. These results may be considered the strain V1 as suitable probiotic candidate.Keywords: antimicrobial, goat‘s milk, Leuconostoc, probiotic
Procedia PDF Downloads 23821533 The Microstructure Development Behavior of Mg-Ag Alloy during High-Temperature Plane Strain Deformation
Authors: Jimin Yun, Yebeen Ji, Kwonhoo Kim
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Magnesium and Mg-Ag system alloys are known to be promising biomaterials due to their high specific strengths and biocompatibility. Because the limited numbers of slip systems were activated in the HCP structure at room temperature, their formability was low. To solve these problems, much research about the improvement of room-temperature formability has been studied, but the microstructure development behaviors of Mg-Ag alloys were still limited. Therefore, this study was conducted to investigate the texture development behaviors of Mg-Ag alloy during high-temperature plane strain deformation. The Ag content of the Mg-Ag alloy used in this study was 3.0, 5.0, and 9.0 wt%. Hot rolling was performed at a temperature of 673K with a reduction ratio of 25%, and these specimens were annealed for 1H at 773K, followed by water quenching at room temperature. High-temperature plane strain deformation was performed under temperatures of 623K and 723K, with strain rates from 0.1/s to 0.05/s and strain from -0.4 to –1.0. As a result, it showed a microstructure and texture similar to the AZ61 alloy, which had been studied previously. It was confirmed that the basal texture became stronger with increasing strains at high-temperature plane strain deformation.Keywords: Mg-Ag, texture, microstructure development behavior, AZ61
Procedia PDF Downloads 5921532 Calculation the Left Ventricle Wall Radial Strain and Radial SR Using Tagged Magnetic Resonance Imaging Data (tMRI)
Authors: Mohammed Alenezy
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The function of cardiac motion can be used as an indicator of the heart abnormality by evaluating longitudinal, circumferential, and Radial Strain of the left ventricle. In this paper, the Radial Strain and SR is studied using tagged MRI (tMRI) data during the cardiac cycle on the mid-ventricle level of the left ventricle. Materials and methods: The short-axis view of the left ventricle of five healthy human (three males and two females) and four healthy male rats were imaged using tagged magnetic resonance imaging (tMRI) technique covering the whole cardiac cycle on the mid-ventricle level. Images were processed using Image J software to calculate the left ventricle wall Radial Strain and radial SR. The left ventricle Radial Strain and radial SR were calculated at the mid-ventricular level during the cardiac cycle. The peak Radial Strain for the human and rat heart was 40.7±1.44, and 46.8±0.68 respectively, and it occurs at 40% of the cardiac cycle for both human and rat heart. The peak diastolic and systolic radial SR for human heart was -1.78 s-1 ± 0.02 s-1 and 1.10±0.08 s-1 respectively, while for rat heart it was -5.16± 0.23s-1 and 4.25±0.02 s-1 respectively. Conclusion: This results show the ability of the tMRI data to characterize the cardiac motion during the cardiac cycle including diastolic and systolic phases which can be used as an indicator of the cardiac dysfunction by estimating the left ventricle Radial Strain and radial SR at different locations of the cardiac tissue. This study approves the validity of the tagged MRI data to describe accurately the cardiac radial motion.Keywords: left ventricle, radial strain, tagged MRI, cardiac cycle
Procedia PDF Downloads 47621531 Effect of Chemical Mutagen on Seeds Germination of Lima Bean
Authors: G. Ultanbekova, Zh. Suleimenova, Zh. Rakhmetova, G. Mombekova, S. Mantieva
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Plant Growth Promoting Rhizobacteria (PGPR) are a group of free-living bacteria that colonize the rhizosphere, enhance plant growth of many cereals and other important agricultural crops and protect plants from disease and abiotic stresses through a wide variety of mechanisms. The use of PGPR has been proven to be an environmentally sound way of increasing crop yields by facilitating plant growth. In the present study, strain improvement of PGPR isolates were carried out by chemical mutagenesis for the improvement of growth and yield of lima bean. Induced mutagenesis is widely used for the selection of microorganisms producing biologically active substances and further improving their activities. Strain improvement is usually done by classical mutagenesis which involves exposing the microbes to chemical or physical mutagens. The strains of Pseudomonas putida 4/1, Azotobacter chroococcum Р-29 and Bacillus subtilis were subjected to mutation process for strain improvement by treatment with a chemical agent (sodium nitrite) to cause mutation and were observed for its consequent action on the seeds germination and plant growth of lima bean (Phaseolus lunatus). Bacterial mutant strains of Pseudomonas putida M-1, Azotobacter chroococcum M-1 and Bacillus subtilis M-1, treated with sodium nitrite in the concentration of 5 mg/ml for 120 min, were found effective to enhance the germination of lima bean seeds compared to parent strains. Moreover, treatment of the lima bean seeds with a mutant strain of Bacillus subtilis M-1 had a significant stimulation effect on plant growth. The length of the stems and roots of lima bean treated with Bacillus subtilis M-1 increased significantly in comparison with parent strain in 1.6 and 1.3 times, respectively.Keywords: chemical mutagenesis, germination, kidney bean, plant growth promoting rhizobacteria (PGPR)
Procedia PDF Downloads 19221530 Numerical Investigation the Effect of Adjustable Guide Vane for Improving the Airflow Rate in Axial Fans
Authors: Behzad Shahizare, N. Nik-Ghazali, Kannan M. Munisamy, Seyedsaeed Tabatabaeikia
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The main objective of this study is to clarify the effect of the adjustable outlet guide vane (OGV) on the axial fan. Three-dimensional Numerical study was performed to analyze the effect of adjustable guide vane for improving the airflow rate in axial fans. Grid independence test was done between five different meshes in order to choose the reliable mesh. In flow analyses, Reynolds averaged Navier-Stokes (RANS) equations was solved using three types of turbulence models named k-ɛ, k-ω and k-ω SST. The aerodynamic performances of the fan and guide vane were evaluated. Numerical method was validated by comparing with experimental test according to AMECA 210 standard. Results showed that, by using the adjustable guide vane the airflow rate is increased around 3% to 6 %. The maximum enhancement of the airflow rate was achieved when pressure was 374pa.Keywords: axial fan, adjustable guide vane, CFD, turbo machinery
Procedia PDF Downloads 32421529 Impact of Religious Struggles on Life Satisfaction among Young Muslims: The Mediating Role of Psychological Wellbeing
Authors: Sarwat Sultan, Frasat Kanwal, Motasem Mirza
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The impact of religiosity on people’s lives has always been found complex because some of them turn to religion to get comfort and relief from their fear, guilt, and illness, whereas some become away due to the perception that God is revengeful and distant for their conduct. The overarching aim of this study was to know whether the relationship between religious struggles (comfort/strain) and life satisfaction is mediated by psychological well-being. The participants of this study were 529 Muslim students who provided their responses on the measures of religious comfort/strain, psychological well-being, and life satisfaction. Results revealed that religious comfort predicted well-being and life satisfaction positively, while religious strain predicted negatively. Findings showed that psychological well-being mediated the prediction of religious comfort and strain for life satisfaction. These findings have implications for students’ mental health because their teachers and professionals can enhance their well-being by teaching them positive aspects of religion and God.Keywords: attitude towards god, religious comfort, religious strain, life satisfaction, psychological wellbeing
Procedia PDF Downloads 5321528 Finite Element Simulation of an Offshore Monopile Subjected to Cyclic Loading Using Hypoplasticity with Intergranular Strain Anisotropy (ISA) for the Soil
Authors: William Fuentes, Melany Gil
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Numerical simulations of offshore wind turbines (OWTs) in shallow waters demand sophisticated models considering the cyclic nature of the environmental loads. For the case of an OWT founded on sands, rapid loading may cause a reduction of the effective stress of the soil surrounding the structure. This eventually leads to its settlement, tilting, or other issues affecting its serviceability. In this work, a 3D FE model of an OWT founded on sand is constructed and analyzed. Cyclic loading with different histories is applied at certain points of the tower to simulate some environmental forces. The mechanical behavior of the soil is simulated through the recently proposed ISA-hypoplastic model for sands. The Intergranular Strain Anisotropy ISA can be interpreted as an enhancement of the intergranular strain theory, often used to extend hypoplastic formulations for the simulation of cyclic loading. In contrast to previous formulations, the proposed constitutive model introduces an elastic range for small strain amplitudes, includes the cyclic mobility effect and is able to capture the cyclic behavior of sands under a larger number of cycles. The model performance is carefully evaluated on the FE dynamic analysis of the OWT.Keywords: offshore wind turbine, monopile, ISA, hypoplasticity
Procedia PDF Downloads 24221527 Analysis and Modeling of Graphene-Based Percolative Strain Sensor
Authors: Heming Yao
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Graphene-based percolative strain gauges could find applications in many places such as touch panels, artificial skins or human motion detection because of its advantages over conventional strain gauges such as flexibility and transparency. These strain gauges rely on a novel sensing mechanism that depends on strain-induced morphology changes. Once a compression or tension strain is applied to Graphene-based percolative strain gauges, the overlap area between neighboring flakes becomes smaller or larger, which is reflected by the considerable change of resistance. Tiny strain change on graphene-based percolative strain sensor can act as an important leverage to tremendously increase resistance of strain sensor, which equipped graphene-based percolative strain gauges with higher gauge factor. Despite ongoing research in the underlying sensing mechanism and the limits of sensitivity, neither suitable understanding has been obtained of what intrinsic factors play the key role in adjust gauge factor, nor explanation on how the strain gauge sensitivity can be enhanced, which is undoubtedly considerably meaningful and provides guideline to design novel and easy-produced strain sensor with high gauge factor. We here simulated the strain process by modeling graphene flakes and its percolative networks. We constructed the 3D resistance network by simulating overlapping process of graphene flakes and interconnecting tremendous number of resistance elements which were obtained by fractionizing each piece of graphene. With strain increasing, the overlapping graphenes was dislocated on new stretched simulation graphene flake simulation film and a new simulation resistance network was formed with smaller flake number density. By solving the resistance network, we can get the resistance of simulation film under different strain. Furthermore, by simulation on possible variable parameters, such as out-of-plane resistance, in-plane resistance, flake size, we obtained the changing tendency of gauge factor with all these variable parameters. Compared with the experimental data, we verified the feasibility of our model and analysis. The increase of out-of-plane resistance of graphene flake and the initial resistance of sensor, based on flake network, both improved gauge factor of sensor, while the smaller graphene flake size gave greater gauge factor. This work can not only serve as a guideline to improve the sensitivity and applicability of graphene-based strain sensors in the future, but also provides method to find the limitation of gauge factor for strain sensor based on graphene flake. Besides, our method can be easily transferred to predict gauge factor of strain sensor based on other nano-structured transparent optical conductors, such as nanowire and carbon nanotube, or of their hybrid with graphene flakes.Keywords: graphene, gauge factor, percolative transport, strain sensor
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