Search results for: Stress Concentration Factors

Authors: Krzysztof J. Czarnocki, E. Czarnocka, K. Szaniawska

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Main goal of the research project is Scaffold Use Risk Assessment Model (SURAM) formulation, developed for the assessment of risk levels as a various construction process stages with various work trades. Finally, in 2016, the project received financing by the National Center for Research and development according to PBS3/A2/19/2015–Research Grant. The presented data, calculations and analyzes discussed in this paper were created as a result of the completion on the first and second phase of the PBS3/A2/19/2015 project. Method: One of the arms of the research project is the assessment of worker visual concentration on the sight zones as well as risky visual point inadequate observation. In this part of research, the mobile eye-tracker was used to monitor the worker observation zones. SMI Eye Tracking Glasses is a tool, which allows us to analyze in real time and place where our eyesight is concentrated on and consequently build the map of worker's eyesight concentration during a shift. While the project is still running, currently 64 construction sites have been examined, and more than 600 workers took part in the experiment including monitoring of typical parameters of the work regimen, workload, microclimate, sound vibration, etc. Full equipment can also be useful in more advanced analyses. Because of that technology we have verified not only main focus of workers eyes during work on or next to scaffolding, but we have also examined which changes in the surrounding environment during their shift influenced their concentration. In the result of this study it has been proven that only up to 45.75% of the shift time, workers’ eye concentration was on one of three work-related areas. Workers seem to be distracted by noisy vehicles or people nearby. In opposite to our initial assumptions and other authors’ findings, we observed that the reflective parts of the scaffoldings were not more recognized by workers in their direct workplaces. We have noticed that the red curbs were the only well recognized part on a very few scaffoldings. Surprisingly on numbers of samples, we have not recognized any significant number of concentrations on those curbs. Conclusion: We have found the eye-tracking method useful for the construction of the SURAM model in the risk perception and worker’s behavior sub-modules. We also have found that the initial worker's stress and work visual conditions seem to be more predictive for assessment of the risky developing situation or an accident than other parameters relating to a work environment.

Keywords: Accident assessment model, eye tracking, occupational safety, scaffolding.

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Authors: Oqba Basal, András Szabó

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Legume crops are able to fix atmospheric nitrogen by the symbiotic relation with specific bacteria, which allows the use of the mineral nitrogen-fertilizer to be reduced, or even excluded, resulting in more profit for the farmers and less pollution for the environment. Soybean (Glycine max (L.) Merrill) is one of the most important legumes with its high content of both protein and oil. However, it is recommended to combine the two nitrogen sources under stress conditions in order to overcome its negative effects. Drought stress is one of the most important abiotic stresses that increasingly limits soybean yields. A precise rate of mineral nitrogen under drought conditions is not confirmed, as it depends on many factors; soybean yield-potential and soil-nitrogen content to name a few. An experiment was conducted during 2017 growing season in Debrecen, Hungary to investigate the effects of nitrogen source on the physiology and the yield of the soybean cultivar 'Boglár'. Three N-fertilizer rates including no N-fertilizer (0 N), 35 kg ha^-1 of N-fertilizer (35 N) and 105 kg ha^-1 of N-fertilizer (105 N) were applied under three different irrigation regimes; severe drought stress (SD), moderate drought stress (MD) and control with no drought stress (ND). Half of the seeds in each treatment were pre-inoculated with Bradyrhizobium japonicum inoculant. The overall results showed significant differences associated with fertilization and irrigation, but not with inoculation. Increasing N rate was mostly accompanied with increased chlorophyll content and leaf area index, whereas it positively affected the plant height only when the drought was waived off. Plant height was the lowest under severe drought, regardless of inoculation and N-fertilizer application and rate. Inoculation increased the yield when there was no drought, and a low rate of N-fertilizer increased the yield furthermore; however, the high rate of N-fertilizer decreased the yield to a level even less than the inoculated control. On the other hand, the yield of non-inoculated plants increased as the N-fertilizer rate increased. Under drought conditions, adding N-fertilizer increased the yield of the non-inoculated plants compared to their inoculated counterparts; moreover, the high rate of N-fertilizer resulted in the best yield. Regardless of inoculation, the mean yield of the three fertilization rates was better when the water amount increased. It was concluded that applying N-fertilizer to provide the nitrogen needed by soybean plants, with the absence of N₂-fixation process, is very important. Moreover, adding relatively high rate of N-fertilizer is very important under severe drought stress to alleviate the drought negative effects. Further research to recommend the best N-fertilizer rate to inoculated soybean under drought stress conditions should be executed.

Keywords: Drought stress, inoculation, N-fertilizer, soybean physiology, yield.

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Authors: Sivapan Choo-In

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The main objective of this study was to investigate particulate matter concentration on main and secondary roadsides in urban area and study the concentration of some heavy metals including lead (Pb), zinc (Zn), copper (Cu) and cadmium (Cd) in particulate matter in the Bangkok area.     

  The averaged particle concentration for main roadsides is higher than secondary roadsides. The particulate matter less than 10 micron concentration contribute the majority of the Total Suspended Particulate matter for main roads and zinc concentrations were higher than copper and lead for both sites.

Keywords: Air Pollution, Air Quality, Pollution and monitoring.

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Authors: Weihong Guo, Dan Brennan, Phil Blythe

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This paper presents the effect of driving a motor vehicle on the stress levels of older drivers, indicated by monitoring their hear rate increase whilst completing various everyday driving tasks. Results suggest that whilst older female drivers heart rate varied more significantly than males, the actual age of a participant did not result in a significant change in heart rate due to stress, within the age group tested. The analysis of the results indicates the most stressful manoeuvres undertaken by the older drivers and highlights the tasks which were found difficult with a view to implementing technologies to aid the more senior driver in automotive travel.

Keywords: Driver stress, heart rate, older driver, road safety, speeding.

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Authors: Imran Siddique

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This paper deals with the helical flow of a Newtonian fluid in an infinite circular cylinder, due to both longitudinal and rotational shear stress. The velocity field and the resulting shear stress are determined by means of the Laplace and finite Hankel transforms and satisfy all imposed initial and boundary conditions. For large times, these solutions reduce to the well-known steady-state solutions.

Keywords: Newtonian fluids, Velocity field, Exact solutions, Shear stress, Cylindrical domains.

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Authors: I. M. Yusuff, O. M. Oni, A. A. Aremu

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Percentage of soil-gas radon-222 concentration (²²²Rn) from soil-depths contributing to outdoor radon atmospheric level depends largely on some physical parameters of the soil. To determine its dependency in soil-depths, survey tests were carried out on soil depths and grain size particles using in-situ measurement method of soil-gas radon-222 concentration at different soil depths. The measurements were carried out with an electronic active radon detector (RAD-7) manufactured by Durridge Company USA. Radon-222 concentrations (²²²Rn) in soil-gas were measured at four different soil depths of 20, 40, 60 and 100 cm in five feasible locations. At each soil depth, soil samples were collected for grain size particle analysis using soil grasp sampler. The result showed that highest value of radon-222 concentration (24,680 ± 1960 Bqm^-3) was measured at 100 cm depth with utmost grain size particle of 17.64% while the lowest concentration (7370 ± 1139 Bqm^-3) was measured at 100 cm depth with least grain size particle of 10.75% respectively. A computational model was derived using SPSS regression package. This model could be a yardstick for prediction on soil gas radon concentration reference to soil grain size particle at different soil-depths.

Keywords: Concentration, radon, porosity, diffusion, colorectal, emanation, yardstick.

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Authors: Lucie Côté, Martin Lauzier, Guy Beauchamp, France Guertin

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Stress causes deleterious effects to the physical, psychological and organizational levels, which highlight the need to use effective coping strategies to deal with it. Several coping models exist, but they don’t integrate the different strategies in a coherent way nor do they take into account the new research on the emotional coping and acceptance of the stressful situation. To fill these gaps, an integrative model incorporating the main coping strategies was developed. This model arises from the review of the scientific literature on coping and from a qualitative study carried out among workers with low or high levels of stress, as well as from an analysis of clinical cases. The model allows one to understand under what circumstances the strategies are effective or ineffective and to learn how one might use them more wisely. It includes Specific Strategies in controllable situations (the Modification of the Situation and the Resignation-Disempowerment), Specific Strategies in non-controllable situations (Acceptance and Stubborn Relentlessness) as well as so-called General Strategies (Wellbeing and Avoidance). This study is intended to undertake and present the process of development and validation of an instrument to measure coping strategies based on this model. An initial pool of items has been generated from the conceptual definitions and three expert judges have validated the content. Of these, 18 items have been selected for a short form questionnaire. A sample of 300 students and employees from a Quebec university was used for the validation of the questionnaire. Concerning the reliability of the instrument, the indices observed following the inter-rater agreement (Krippendorff’s alpha) and the calculation of the coefficients for internal consistency (Cronbach's alpha) are satisfactory. To evaluate the construct validity, a confirmatory factor analysis using MPlus supports the existence of a model with six factors. The results of this analysis suggest also that this configuration is superior to other alternative models. The correlations show that the factors are only loosely related to each other. Overall, the analyses carried out suggest that the instrument has good psychometric qualities and demonstrates the relevance of further work to establish predictive validity and reconfirm its structure. This instrument will help researchers and clinicians better understand and assess coping strategies to cope with stress and thus prevent mental health issues.

Keywords: Acceptance, coping strategies, measurement instrument, questionnaire, stress, validation process.

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Authors: M. D. S. Siti-Normah, S. Sabiha-Hanim, A. Noraishah

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Agricultural residue such as oil palm fronds (OPF) is cheap, widespread and available throughout the year. Hemicelluloses extracted from OPF can be hydrolyzed to their monomers and used in production of xylooligosaccharides (XOs). The objective of the present study was to optimize the enzymatic hydrolysis process of OPF hemicellulose by varying pH, temperature, enzyme and substrate concentration for production of XOs. Hemicelluloses was extracted from OPF by using 3 M potassium hydroxide (KOH) at temperature of 40°C for 4 hrs and stirred at 400 rpm. The hemicellulose was then hydrolyzed using Trichoderma longibrachiatum xylanase at different pH, temperature, enzyme and substrate concentration. XOs were characterized based on reducing sugar determination. The optimum conditions to produced XOs from OPF hemicellulose was obtained at pH 4.6, temperature of 40°C , enzyme concentration of 2 U/mL and 2% substrate concentration. The results established the suitability of oil palm fronds as raw material for production of XOs.

Keywords: Hemicellulose, oil palm fronds, Trichoderma longibrachiatum, xylooligosaccharides.

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Authors: Djarot B. Darmadi

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The wider growing Finite Element Method (FEM) application is caused by its benefits of cost saving and environment friendly. Also, by using FEM a deep understanding of certain phenomenon can be achieved. This paper observed the role of material properties and volumetric change when Solid State Phase Transformation (SSPT) takes place in residual stress formation due to a welding process of ferritic steels through coupled Thermo- Metallurgy-Mechanical (TMM) analysis. The correctness of FEM residual stress prediction was validated by experiment. From parametric study of the FEM model, it can be concluded that the material properties change tend to over-predicts residual stress in the weld center whilst volumetric change tend to underestimates it. The best final result is the compromise of both by incorporates them in the model which has a better result compared to a model without SSPT.

Keywords: Residual stress, ferritic steels, SSPT, coupled-TMM.

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Authors: Raheleh Khademian, Roghayeh Aminian

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For the study of salinity stress on Vicia villosa and calcium effect for modulation of that, an experiment was conducted under hydroponic condition, and some important morphological and physiological characteristics were evaluated. This experiment was conducted as a factorial based on randomized complete design with three replications. The treatments include salinity stress in three levels (0, 50, and 100 mM NaCl) and calcium in two levels (content in Hoagland solution and double content). The results showed that all morphological and physiological traits include root and shoot length, root and shoot wet and dry weight, leaf area, leaf chlorophyll content, RWC, CMS, and biological yield was significantly different from the control and is affected by the salinity stress severely. But, calcium effect on them was not significant despite of decreasing salinity effect.

Keywords: Vicia villossa, salinity stress, calcium, hydroponic.

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Authors: Parvaneh Vafa, Rahim Naseri, Meysam Moradi

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In order to study the effect of drought stress on grain yield, yield components and associated traits of durum wheat cultivars, an experiment was done as split plot arrangement using randomized complete block design with three replications in Ilam province, Iran in 2009-2010 cropping season. Different levels of irrigation (Full irrigation, drought stress at stem elongation, Flowering and grain formation stages) were considered as a main plot and three durum wheat cultivars (Yavaros, Seimareh and Karkheh) were assigned as a sub plot. The results showed that drought stress was significant on grain yield, spike.m-2, grain. Spike-1, 1000-grain weight, biological yield, harvest index and protein content. Drought stress at all stages caused a loss in grain yield and its components. Full irrigation had the highest grain yield and yield components. Drought stress at stem elongation, flowering and grain formation stages caused a reduction in spike.m-2, grain.spike-1 and 1000-grain weight, respectively. Protein content was significantly affected by drought stress. The highest protein content was obtained from drought stress at grain formation stage. Cultivars had an influence on grain yield and yield components. Yavaros and Seimareh cultivars had the highest and lowest grain yield, respectively. Interaction effect between drought stress and cultivar had a significant effect on grain and yield components. Full irrigation and Yavaros cultivar had the highest grain yield and drought stress at grain formation stage and Seimareh cultivar had the lowest grain yield, respectively.

Keywords: Durum wheat, Drought stress, Grain yield.

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Authors: Babak Abazadeh, Hadi Rezghi Maleki

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In this paper the fatigue crack initiation location of double shear lap joints, treated by interference fit and bolt clamping, have been investigated both experimentally and numerically. To do so, using the fracture section of available fatigue tested specimens of interference fitted and torque tightened Aluminum 2024-T3 plates, the crack initiation location was determined. The stress distribution attained from the finite element analysis was used to help explain the results observed in the experimental tests. The results showed that the fatigue crack initiation location changes from top and mid plane at the hole edge to somewhere far from the hole edge (stress concentration region) in different combination of clamping force, interference fit size and applied cyclic load ranges. It is worth mentioning that the fatigue crack initiation location affects the fatigue life of the specimens too.

Keywords: Fatigue crack initiation, interference fit, bolt clamping, double shear lap joint.

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Authors: Krzysztof J. Czarnocki, F. Silveira, E. Czarnocka, K. Szaniawska

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Research background: Problems related to the occupational health and decreasing level of safety occur commonly in the construction industry. Important factor in the occupational safety in construction industry is scaffold use. All scaffolds used in construction, renovation, and demolition shall be erected, dismantled and maintained in accordance with safety procedure. Increasing demand for new construction projects unfortunately still is linked to high level of occupational accidents. Therefore, it is crucial to implement concrete actions while dealing with scaffolds and risk assessment in construction industry, the way on doing assessment and liability of assessment is critical for both construction workers and regulatory framework. Unfortunately, professionals, who tend to rely heavily on their own experience and knowledge when taking decisions regarding risk assessment, may show lack of reliability in checking the results of decisions taken. Purpose of the article: The aim was to indicate crucial parameters that could be modeling with Risk Assessment Model (RAM) use for improving both building enterprise productivity and/or developing potential and safety climate. The developed RAM could be a benefit for predicting high-risk construction activities and thus preventing accidents occurred based on a set of historical accident data. Methodology/Methods: A RAM has been developed for assessing risk levels as various construction process stages with various work trades impacting different spheres of enterprise activity. This project includes research carried out by teams of researchers on over 60 construction sites in Poland and Portugal, under which over 450 individual research cycles were carried out. The conducted research trials included variable conditions of employee exposure to harmful physical and chemical factors, variable levels of stress of employees and differences in behaviors and habits of staff. Genetic modeling tool has been used for developing the RAM. Findings and value added: Common types of trades, accidents, and accident causes have been explored, in addition to suitable risk assessment methods and criteria. We have found that the initial worker stress level is more direct predictor for developing the unsafe chain leading to the accident rather than the workload, or concentration of harmful factors at the workplace or even training frequency and management involvement.

Keywords: Civil engineering, occupational health, productivity, safety climate.

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Authors: I. Made Gatot Karohika, Shigeyuki Haruyama, Ken Kaminishi, Oke Oktavianty, Didik Nurhadiyanto

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Contact width and contact stress are important parameters related to the leakage behavior of corrugated metal gasket. In this study, contact width and contact stress of three-layer corrugated metal gasket are investigated due to the modulus of elasticity and thickness of surface layer for 2 type gasket (0-MPa and 400-MPa mode). A finite element method was employed to develop simulation solution to analysis the effect of each parameter. The result indicated that lowering the modulus of elasticity ratio of surface layer will result in better contact width but the average contact stresses are smaller. When the modulus of elasticity ratio is held constant with thickness ratio increase, its contact width has an increscent trend otherwise the average contact stress has decreased trend.

Keywords: Contact width, contact stress, layer, metal gasket, corrugated, simulation.

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Authors: H.R. Balouchi

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To evaluate genetic variation of wheat (Triticum aestivum) affected by heat and drought stress on eight Australian wheat genotypes that are parents of Doubled Haploid (HD) mapping populations at the vegetative stage, the water stress experiment was conducted at 65% field capacity in growth room. Heat stress experiment was conducted in the research field under irrigation over summer. Result show that water stress decreased dry shoot weight and RWC but increased osmolarity and means of Fv/Fm values in all varieties except for Krichauff. Krichauff and Kukri had the maximum RWC under drought stress. Trident variety was shown maximum WUE, osmolarity (610 mM/Kg), dry mater, quantum yield and Fv/Fm 0.815 under water stress condition. However, the recovery of quantum yield was apparent between 4 to 7 days after stress in all varieties. Nevertheless, increase in water stress after that lead to strong decrease in quantum yield. There was a genetic variation for leaf pigments content among varieties under heat stress. Heat stress decreased significantly the total chlorophyll content that measured by SPAD. Krichauff had maximum value of Anthocyanin content (2.978 A/g FW), chlorophyll a+b (2.001 mg/g FW) and chlorophyll a (1.502 mg/g FW). Maximum value of chlorophyll b (0.515 mg/g FW) and Carotenoids (0.234 mg/g FW) content belonged to Kukri. The quantum yield of all varieties decreased significantly, when the weather temperature increased from 28 ÔùªC to 36 ÔùªC during the 6 days. However, the recovery of quantum yield was apparent after 8th day in all varieties. The maximum decrease and recovery in quantum yield was observed in Krichauff. Drought and heat tolerant and moderately tolerant wheat genotypes were included Trident, Krichauff, Kukri and RAC875. Molineux, Berkut and Excalibur were clustered into most sensitive and moderately sensitive genotypes. Finally, the results show that there was a significantly genetic variation among the eight varieties that were studied under heat and water stress.

Keywords: Abiotic stress, Genetic variation, Fluorescence, Wheat genotypes.

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Authors: Aliaa M. El-Borai, Ehab A. Beltagy, Eman E. Gadallah, Samy A. ElAssar

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Bioremediation technology is now used for treatment instead of traditional metal removal methods. A strain was isolated from Marsa Alam, Red sea, Egypt showed high resistance to high lead concentration and was identified by the 16S rRNA gene sequencing technique as Halomonas sp. ES015. Medium optimization was carried out using Plackett-Burman design, and the most significant factors were yeast extract, casamino acid and inoculums size. The optimized media obtained by the statistical design raised the removal efficiency from 84% to 99% from initial concentration 250 ppm of lead. Moreover, Box-Behnken experimental design was applied to study the relationship between yeast extract concentration, casamino acid concentration and inoculums size. The optimized medium increased removal efficiency to 97% from initial concentration 500 ppm of lead. Immobilized Halomonas sp. ES015 cells on sponge cubes, using optimized medium in loop bioremediation column, showed relatively constant lead removal efficiency when reused six successive cycles over the range of time interval. Also metal removal efficiency was not affected by flow rate changes. Finally, the results of this research refer to the possibility of lead bioremediation by free or immobilized cells of Halomonas sp. ES015. Also, bioremediation can be done in batch cultures and semicontinuous cultures using column technology.

Keywords: Bioremediation, lead, Box–Behnken, Halomonas sp. ES015, loop bioremediation, Plackett-Burman.

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Authors: Shang-Han Tsai, Yong-Hong Lin, Chung-Ruey Yen

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Waxapple (Syzygium samarngense Merr.et Perry) is an important tropical fruit in Taiwan. The famous producing area is located on the coast in Pingtung County. Land subsidence and climate change will tend to soil alkalization more seriously. This study was to evaluate the effects of NaCl in waxapple seedlings. NaCl salinity reduced waxapple shoot growth; it may due to reducing relative water content in leaf and new shoot. Leaf Cl and Na concentration were increased but K, Ca, and Mg content had no significant difference after irrigated with NaCl for six weeks. In roots, Na and Cl content increase significantly with 90 mM NaCl treatment, but K, Ca, and Mg content was reduced. 30-90mM Nacl treatment do not effect K/Na, Ca/Na and Mg/Na ratio, but decrease significantly in 90mM treatment in roots. The leaf and root electrolyte leakage were significantly affected by 90 mM NaCl treatment. Suggesting 90mM was optimum concentration for sieve out other tolerance waxapples verities.

Keywords: Growth, NaCl stress, Nutrient, Waxapple.

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Authors: M. Jalali Azizpour, H. Mohammadi Majd

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High velocity oxygen fuel (HVOF) spray technique is one of the leading technologies that have been proposed as an alternative to the replacement of electrolytic hard chromium plating in a number of engineering applications. In this study, WC-Co powder was coated on AISI1045 steel using high velocity oxy fuel (HVOF) method. The sin²ψ method was used to evaluate the through thickness residual stress by means of XRD after mechanical layer removal process (only grinding). The average of through thickness residual stress using X-Ray diffraction was -400 MPa.

Keywords: Grinding, HVOF, Thermal spray, WC-Co.

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Authors: Kyongsoo Lee, , Seong-Il Kim, Byeong-Kwon Ju

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An aqueous methanol sensor for use in direct methanol fuel cells (DMFCs) applications is demonstrated; the methanol sensor is built using dispersed single-walled carbon nanotubes (SWCNTs) with Nafion117 solution to detect the methanol concentration in water. The study is aimed at the potential use of the carbon nanotubes array as a methanol sensor for direct methanol fuel cells (DMFCs). The concentration of methanol in the fuel circulation loop of a DMFC system is an important operating parameter, because it determines the electrical performance and efficiency of the fuel cell system. The sensor is also operative even at ambient temperatures and responds quickly to changes in the concentration levels of the methanol. Such a sensor can be easily incorporated into the methanol fuel solution flow loop in the DMFC system.

Keywords: methanol concentration, SWCNT, nafion composites

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Authors: S. A. Mousavi Rad, S. A. Mirbagheri, T. Mohammadi

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In this paper, removal of chromium(VI) from aqueous solution has been researched using reverse osmosis. The influence of transmembrane pressure and feed concentration on permeate flux, water recovery, permeate concentration, and salt rejection was studied. The results showed that according to the variation of transmembrane pressure and feed concentration, the permeate flux and salt rejection were in the range 19.17 to 58.75 l/m2.min and 99.51 to 99.8 %, respectively. The highest permeate flux, 58.75 l/m2.min, and water recovery, 42.47 %, were obtained in the highest pressure and the lowest feed concentration. On the other hand, the lowest permeate concentration, 0.01 mg/l, and the highest salt rejection, 99.8 %, were obtained in the highest pressure and the lowest feed concentration.

Keywords: solution, Chromium, Removal, Reverse osmosis.

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Authors: Jahanfar Daneshian, P. Jonoubi, D. Barari Tari

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In order to investigate water deficit stress on 24 of soybean (Glycine Max. L) cultivars and lines in temperate climate, an experiment was conducted in Iran Seed and Plant Improvement Institute. Stress levels were irrigation after evaporation of 50, 100, 150 mm water from pan, class A. Randomized Completely Block Design was arranged for each stress levels. Some traits such as, node number, plant height, pod number per area, grain number per pod, grain number per area, 1000 grains weight, grain yield and harvest index were measured. Results showed that water deficit stress had significant effect on node number, plant height, pod number per area, grain number per pod, grain number per area, 1000 grains weight and harvest index. Also all of agronomic traits except harvest index influenced significantly by cultivars and lines. The least and most grain yield was belonged to Ronak X Williams and M41 x Clark respectively.

Keywords: Soybean, water deficit stress, Agronomic traits, Yield

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Authors: A. Derardja, L. Baroura, M. Brioua

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The nanotechnology based on epitaxial systems includes single or arranged misfit dislocations. In general, whatever is the type of dislocation or the geometry of the array formed by the dislocations; it is important for experimental studies to know exactly the stress distribution for which there is no analytical expression [1, 2]. This work, using a numerical analysis, deals with relaxation of epitaxial layers having at their interface a periodic network of edge misfit dislocations. The stress distribution is estimated by using isotropic elasticity. The results show that the thickness of the two sheets is a crucial parameter in the stress distributions and then in the profile of the two sheets. A comparative study between the case of single dislocation and the case of parallel network shows that the layers relaxed better when the interface is covered by a parallel arrangement of misfit. Consequently, a single dislocation at the interface produces an important stress field which can be reduced by inserting a parallel network of dislocations with suitable periodicity.

Keywords: Parallel array of misfit, interface, isotropic elasticity, single crystalline substrates, coherent interface

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Authors: M. Sumida

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An experimental investigation was performed on pulp liquid flow in straight ducts with a square cross section. Fully developed steady flow was visualized and the fiber concentration was obtained using a light-section method developed by the author et al. The obtained results reveal quantitatively, in a definite form, the distribution of the fiber concentration. From the results and measurements of pressure loss, it is found that the flow characteristics of pulp liquid in ducts can be classified into five patterns. The relationships among the distributions of mean and fluctuation of fiber concentration, the pressure loss and the flow velocity are discussed, and then the features for each pattern are extracted. The degree of nonuniformity of the fiber concentration, which is indicated by the standard deviation of its distribution, is decreased from 0.3 to 0.05 with an increase in the velocity of the tested pulp liquid from 0.4 to 0.8%.

Keywords: Fiber Concentration, Flow Characteristic, Pulp Liquid, Straight Duct.

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Authors: Biao Wang, Tao Li, Qi-wen Sun, Wei-yong Ying, Ding-ye Fang

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Methanol-to-olefins (MTO) coupled with transformation of coal or natural gas to methanol gives an interesting and promising way to produce ethylene and propylene. To investigate solid concentration in gas-solid fluidized bed for methanol-to-olefins process catalyzed by SAPO-34, a cold model experiment system is established in this paper. The system comprises a gas distributor in a 300mm internal diameter and 5000mm height acrylic column, the fiber optic probe system and series of cyclones. The experiments are carried out at ambient conditions and under different superficial gas velocity ranging from 0.3930m/s to 0.7860m/s and different initial bed height ranging from 600mm to 1200mm. The effects of radial distance, axial distance, superficial gas velocity, initial bed height on solid concentration in the bed are discussed. The effects of distributor shape and porosity on solid concentration are also discussed. The time-averaged solid concentration profiles under different conditions are obtained.

Keywords: Branched pipe distributor, distributor porosity, gas-solid fluidized bed, solid concentration.

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Authors: Chuan-Kun Liu, Chi-Wang Li

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Simultaneous recovery of copper and DCA from simulated MEUF concentrated stream was investigated. Effects of surfactant (DCA) and metal (copper) concentrations, surfactant to metal molar ratio (S/M ratio), electroplating voltage, EDTA concentration, solution pH, and salt concentration on metal recovery and current efficiency were studied. Electric voltage of -0.5 V was shown to be optimum operation condition in terms of Cu recovery, current efficiency, and surfactant recovery. Increasing Cu recovery and current efficiency were observed with increases of Cu concentration while keeping concentration of DCA constant. However, increasing both Cu and DCA concentration while keeping S/M ratio constant at 2.5 showed detrimental effect on Cu recovery at DCA concentration higher than 15 mM. Cu recovery decreases with increasing pH while current efficiency showed an opposite trend. It is believed that conductivity is the main cause for discrepancy of Cu recovery and current efficiency observed at different pH. Finally, it was shown that EDTA had adverse effect on both Cu recovery and current efficiency while addition of NaCl salt had negative impact on current efficiency at concentration higher than 8000 mg/L.

Keywords: metal recovery, MEUF waste, surfactant, electroplating.

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Authors: B.Tavakoly Sany, A. Salleh, A.H .Sulaiman, A. Mehdinia, GH. Monazami

Abstract:

One year (November 2009-October 2010) sediment monitoring was used to evaluate pollution status, concentration and distribution of heavy metals (As, Cu, Cd, Cr, Hg, Ni, Pb and Zn) in West Port of Malaysia. Sediment sample were collected from nine stations every four months. Geo-accumulation factor and Pollution Load Index (PLI) were estimated to better understand the pollution level in study area. The heavy metal concentration (Mg/g dry weight) were ranged from 20.2 to 162 for As, 7.4 to 27.6 for Cu, 0.244 to 3.53 for Cd, 11.5 to 61.5 for Cr, 0.11 to 0.409 for Hg, 7.2 to 22.2 for Ni, 22.3 to 80 for Pb and 23 to 98.3 for Zn. In general, concentration some metals (As,Cd, Hg and Pb) was higher than background values that are considered as serious concern for aquatic life and the human health.

Keywords: Heavy metals, Sediment Quality, geo-accumulationindex, Pollution Load Index

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Authors: H. Panahi, S. Asadi

Abstract:

In this paper, the estimation of the stress-strength parameter R = P(Y < X), when X and Y are independent and both are Lomax distributions with the common scale parameters but different shape parameters is studied. The maximum likelihood estimator of R is derived. Assuming that the common scale parameter is known, the bayes estimator and exact confidence interval of R are discussed. Simulation study to investigate performance of the different proposed methods has been carried out.

Keywords: Stress-Strength model; maximum likelihoodestimator; Bayes estimator; Lomax distribution

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Authors: H.R. Balouchi

Abstract:

To evaluate genetic variation of wheat (Triticum aestivum) affected by heat and drought stress on eight Australian wheat genotypes that are parents of Doubled Haploid (HD) mapping populations at the vegetative stage, the water stress experiment was conducted at 65% field capacity in growth room. Heat stress experiment was conducted in the research field under irrigation over summer. Result show that water stress decreased dry shoot weight and RWC but increased osmolarity and means of Fv/Fm values in all varieties except for Krichauff. Krichauff and Kukri had the maximum RWC under drought stress. Trident variety was shown maximum WUE, osmolarity (610 mM/Kg), dry mater, quantum yield and Fv/Fm 0.815 under water stress condition. However, the recovery of quantum yield was apparent between 4 to 7 days after stress in all varieties. Nevertheless, increase in water stress after that lead to strong decrease in quantum yield. There was a genetic variation for leaf pigments content among varieties under heat stress. Heat stress decreased significantly the total chlorophyll content that measured by SPAD. Krichauff had maximum value of Anthocyanin content (2.978 A/g FW), chlorophyll a+b (2.001 mg/g FW) and chlorophyll a (1.502 mg/g FW). Maximum value of chlorophyll b (0.515 mg/g FW) and Carotenoids (0.234 mg/g FW) content belonged to Kukri. The quantum yield of all varieties decreased significantly, when the weather temperature increased from 28 ÔùªC to 36 ÔùªC during the 6 days. However, the recovery of quantum yield was apparent after 8th day in all varieties. The maximum decrease and recovery in quantum yield was observed in Krichauff. Drought and heat tolerant and moderately tolerant wheat genotypes were included Trident, Krichauff, Kukri and RAC875. Molineux, Berkut and Excalibur were clustered into most sensitive and moderately sensitive genotypes. Finally, the results show that there was a significantly genetic variation among the eight varieties that were studied under heat and water stress.

Keywords: Abiotic stress, genetic variation, fluorescence, wheat genotypes.

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Authors: P. Gunnasegaran, M. Z. Abdullah, M. Z. Yusoff, Nur Irmawati

Abstract:

This study presents experimental and optimization of nanoparticle mass concentration and heat input based on the total thermal resistance (Rth) of loop heat pipe (LHP), employed for PCCPU cooling. In this study, silica nanoparticles (SiO2) in water with particle mass concentration ranged from 0% (pure water) to 1% is considered as the working fluid within the LHP. The experimental design and optimization is accomplished by the design of experimental tool, Response Surface Methodology (RSM). The results show that the nanoparticle mass concentration and the heat input have significant effect on the Rth of LHP. For a given heat input, the Rth is found to decrease with the increase of the nanoparticle mass concentration up to 0.5% and increased thereafter. It is also found that the Rth is decreased when the heat input is increased from 20W to 60W. The results are optimized with the objective of minimizing the Rth, using Design-Expert software, and the optimized nanoparticle mass concentration and heat input are 0.48% and 59.97W, respectively, the minimum thermal resistance being 2.66 (ºC/W).

Keywords: Loop heat pipe, nanofluid, optimization, thermal resistance.

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Authors: Tsun-Hui Huang, Shyue-Cheng Yang, Chiou-Fen Shieh

Abstract:

In this paper, a nonlinear constitutive law and a curve fitting, two relationships between the stress-strain and the shear stress-strain for sandstone material were used to obtain a second-order polynomial constitutive equation. Based on the established polynomial constitutive equations and Newton’s second law, a mathematical model of the non-homogeneous nonlinear wave equation under an external pressure was derived. The external pressure can be assumed as an impulse function to simulate a real earthquake source. A displacement response under nonlinear two-dimensional wave equation was determined by a numerical method and computer-aided software. The results show that a suit pressure in the sandstone generates the phenomenon of stress solitary waves.

Keywords: Polynomial constitutive equation, solitary.

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