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Sample records for time stirring speed

  1. OPTIMIZATION OF STIRRING SPEED AND STIRRING TIME TOWARD NANOPARTICLE SIZE OF CHITOSAN-SIAM CITRUS PEEL (Citrus nobilis L.var Microcarpa 70% ETHANOL EXTRACT

    Directory of Open Access Journals (Sweden)

    Wintari Taurina

    2017-04-01

    Full Text Available Siam citrus peel (Citrus nobilis L. var. Microcarpa is a plant derived from Sambas Regency, West Kalimantan Province. Bioavailability of herbal active compounds can be enhanced by formulating extract into nanoparticle. The polymer used was chitosan with crosslinker Na-TPP. Stirring speed and stirring time play an important role to produce small particle size in forming nanoparticle using ionic gelation method. Enhancement of stirring speed and stirring time could reduce particle size. Nanoparticles were prepared using ionic gelation method by mixing Na-TPP, extract and chitosan (1:1:6 with varying the stirring speed 500 rpm, 1000 rpm, 1500 rpm and stirring time 1 hrs, 2 hrs, 3 hrs. The particle size of nanoparticle was found to be 85.3 nm at 1000 rpm of stirring speed and 3 hrs of stirring times, with polidispersity index 0.287, zeta potential +32.37 mV and entrapment efficiency 87.12 %.

  2. Effects of tool speeds and corresponding torque/energy on stir zone formation during friction stir welding/processing

    International Nuclear Information System (INIS)

    Cui, S; Chen, Z W

    2009-01-01

    The way processing parameters and the measurable thermomechanical responses relate to the individual and combined flows forming the different processed zones during friction stir welding/processing has been studied. Experimentally, a cast Al-7Si-0.3Mg alloy was used to provide readily identifiable processed zones. A series of friction stir experiments covering a wide range of tool forward and rotation speeds were conducted followed by the measurement of individual and combined stir areas. It has been found that the basic modes of material flow did not change but the relative volume of each flow depended on both forward and rotation speeds. The trends observed in the present data explain how pin rotation relates to the material transportation mechanism and the associated torque required. This data also explains how forward speed, not rotation speed, relates to specific energy and the volume of the total stir zone.

  3. Optimization of Friction Stir Welding Tool Advance Speed via Monte-Carlo Simulation of the Friction Stir Welding Process.

    Science.gov (United States)

    Fraser, Kirk A; St-Georges, Lyne; Kiss, Laszlo I

    2014-04-30

    Recognition of the friction stir welding process is growing in the aeronautical and aero-space industries. To make the process more available to the structural fabrication industry (buildings and bridges), being able to model the process to determine the highest speed of advance possible that will not cause unwanted welding defects is desirable. A numerical solution to the transient two-dimensional heat diffusion equation for the friction stir welding process is presented. A non-linear heat generation term based on an arbitrary piecewise linear model of friction as a function of temperature is used. The solution is used to solve for the temperature distribution in the Al 6061-T6 work pieces. The finite difference solution of the non-linear problem is used to perform a Monte-Carlo simulation (MCS). A polynomial response surface (maximum welding temperature as a function of advancing and rotational speed) is constructed from the MCS results. The response surface is used to determine the optimum tool speed of advance and rotational speed. The exterior penalty method is used to find the highest speed of advance and the associated rotational speed of the tool for the FSW process considered. We show that good agreement with experimental optimization work is possible with this simplified model. Using our approach an optimal weld pitch of 0.52 mm/rev is obtained for 3.18 mm thick AA6061-T6 plate. Our method provides an estimate of the optimal welding parameters in less than 30 min of calculation time.

  4. Improvement of lipase production at different stirring speeds and oxygen levels

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    F.O.M. Alonso

    2005-03-01

    Full Text Available Lipase production by a Brazilian wild strain of Yarrowia lipolytica at different stirring speeds and air flow rates was studied. The relationship among lipid consumption, cell growth and lipase production by this microorganism is presented. The most pronounced effect of oxygen on lipase production was determined by stirring speed. Maximum lipase activity was detected in the late stationary phase at 200 rpm and an air flow rate of 1-2 dm³/min (0.8-1.7 vvm when the lipid source had been fully consumed. Higher stirring speeds resulted in mechanical and/or oxidative stress, while lower stirring speeds seemed to limit oxygen levels. An increase in the availability of oxygen at higher air flow rates led to faster lipid uptake and anticipation of enzyme release into the culture medium. The highest lipase production was obtained at 200 rpm and 1 dm³/min (0.8 vvm.

  5. Effect of welding speed on microstructural and mechanical properties of friction stir welded Inconel 600

    International Nuclear Information System (INIS)

    Song, K.H.; Fujii, H.; Nakata, K.

    2009-01-01

    In order to evaluate the properties of a friction stir welded Ni base alloy, Inconel 600 (single phase type) was selected. Sound friction stir welds without weld defect were obtained at 150 and 200 mm/min in welding speed, however, a groove like defect occurred at 250 mm/min. The electron back scattered diffraction (EBSD) method was used to analyze the grain boundary character distribution. As a result, dynamic recrystallization was observed at all conditions, and the grain refinement was achieved in the stir zone, and it was gradually accelerated from 19 μm in average grain size of the base material to 3.4 μm in the stir zone with increasing the welding speed. It also has an effect on the mechanical properties so that friction stir welded zone showed 20% higher microhardness and 10% higher tensile strength than those of base material.

  6. Effect of rotation speed and welding speed on Friction Stir Welding of AA1100 Aluminium alloy

    Science.gov (United States)

    Raja, P.; Bojanampati, S.; Karthikeyan, R.; Ganithi, R.

    2018-04-01

    Aluminum AA1100 is the most widely used grade of Aluminium due to its excellent corrosion resistance, high ductility and reflective finish, the selected material was welded with Friction Stir Welding (FSW) process on a CNC machine, using a combination of different tool rotation speed (1500 rpm, 2500 rpm, 3500 rpm) and welding speed (10 mm/min, 30 mm/min, 50 mm/min) as welding parameters. The effect of FSW using this welding parameter was studied by measuring the ultimate tensile strength of the welded joints. A high-speed steel tool was prepared for welding the Aluminium AA1100 alloy having an 8mm shoulder diameter and pin dimension of 4mm diameter and 2.8 mm length. The welded joints were tested using the universal testing machine. It was found that Ultimate Tensile Strength of FSW specimen was highest with a value of 98.08 MPa when the weld was performed at rotation speed of 1500 RPM and welding speed of 50 mm/min.

  7. Batch leachate treatment using stirred electrocoagulation reactor with variation of residence time and stirring rate

    Science.gov (United States)

    Sitorus, I. S.; Astono, W.; Iswanto, B.

    2018-01-01

    This study aims to reduce pollutant levels of the leachate by electrocoagulation method using a stirred electrocoagulation reactor as the electrochemical water treatment. The release of active coagulants as metallic ions took place in the anode, while in the cathode, the electrolysis reaction in the form of hydrogen gas dischargeoccurred. The source of wastewater is Waste Water Treatment Plant inlet III of Bantar Gebang, Bekasi. Some parameters were analyzed in this research, i.e., Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), NH3, NO3 -, NO2 -, N-total, and organic substances as well as the microorganism growth before and after electrocoagulation, with variations of detention time (seconds) of 10, 20, 120, 600 and rapid mixing conditions (rpm) of 60, 100 and 200. The results show that the greater the rapid mixing speed and the detention time of electrolysis, the higher the removal of contaminants in liquid waste. The optimum condition of electrocoagulation was encountered at 200 rpm rapid mixing with 600 seconds of processing time. The removal efficiencies of electrocoagulation method for each parameter are TSS of 46.80%, BOD5 of 71.33%, COD of 73.77%, Pb of 62.5%,and NH3-N of 57.92%,whereas the pH value has been increased from 8.03 to 8.95. The electrocoagulation method can reduce levels of pollutants, complying with the environmental standards.

  8. The effect of time and stirring on product white colorant from titanium dioxide

    International Nuclear Information System (INIS)

    Ratnawati; Linda A; Yoshi; Zaenal K; Andri Y

    2018-01-01

    White Colorant is the main raw material in the paint making process in the depots. It made from TiO 2 pigment. The process of making white colorant requires a great stirring time and energy to mix the materials such as binders, pigments, solvents, and additives. The aim of this study is to get the optimum stirring time and speed from mixing the materials needed to obtain white colorant from TiO 2 pigment that meet the specification desired by paint Factory in Tangerang that is particle size of TiO 2 (10 μm to 30 μm), viscosity 1000 cps to 6000 cps, total solids 79 % to 83 %, DE color is 0.5, and CR is 80 % to 100 %. Variations made were stirring speed (1000, 1100 and 1200) rpm and stirring time(10, 15, 20, 25 and 30) minutes. The optimum results obtained are particle size of 15 μm, viscosity 1900 cps, total solids 81.81 %, color DE 0.49 and color CR 98.12 % at stirring condition 1200 rp min 15 minutes. (author)

  9. Nugget Structure Evolution with Rotation Speed for High-Rotation-Speed Friction-Stir-Welded 6061 Aluminum Alloy

    Science.gov (United States)

    Zhang, H. J.; Wang, M.; Zhu, Z.; Zhang, X.; Yu, T.; Wu, Z. Q.

    2018-03-01

    High-rotation-speed friction stir welding (HRS-FSW) is a promising technique to reduce the welding loads during FSW and thus facilitates the application of FSW for in situ fabrication and repair. In this study, 6061 aluminum alloy was friction stir welded at high-rotation speeds ranging from 3000 to 7000 rpm at a fixed welding speed of 50 mm/min, and the effects of rotation speed on the nugget zone macro- and microstructures were investigated in detail in order to illuminate the process features. Temperature measurements during HRS-FSW indicated that the peak temperature did not increase consistently with rotation speed; instead, it dropped remarkably at 5000 rpm because of the lowering of material shear stress. The nugget size first increased with rotation speed until 5000 rpm and then decreased due to the change of the dominant tool/workpiece contact condition from sticking to sliding. At the rotation speed of 5000 rpm, where the weld material experienced weaker thermal effect and higher-strain-rate plastic deformation, the nugget exhibited relatively small grain size, large textural intensity, and high dislocation density. Consequently, the joint showed superior nugget hardness and simultaneously a slightly low tensile ductility.

  10. Tensile Properties of Friction Stir Welded Joints of AA 2024-T6 Alloy at Different Welding Speeds

    Science.gov (United States)

    Avula, Dhananjayulu; Devuri, Venkateswarlu; Cheepu, Muralimohan; Dwivedi, Dheerendra Kumar

    2018-03-01

    The influence of welding speed on the friction stir welded joint properties of hardness, tensile properties, defects and microstructure characterization are studied in the present study. The friction stir welding was conducted on AA2014-T6 heat treated alloy with 5 mm thickness plate in butt joint configuration. The welding speed was varied from 8 mm/min to 120 mm/min at the fixed travel speed and load conditions. It is observed that the welding speeds at higher rate with wide range can be possible to weld this alloy at higher rates of tool revolution suggesting that the inherent capability of friction stir welding technique for aluminum 2014 alloys. The strength of the joints gradually increases with enhancing of welding speed. The micro structural observations exhibited the formation of equiaxed grains in the stir zone and slightly in the thermo-mechanically affected zone. In addition, the size of the grains decreases with increase in welding speed owing to the presence of low heat input. Hence the hardness of the joints slightly increased in the stir zones over the other zones of the weld nugget. The joint strength initially increases with the welding speed and starts to decreases after reaching to the maximum value. The relationship between the welding conditions and friction stir welded joint properties has been discussed.

  11. Impact of stirring speed, glycerin and sodium chloride concentrations on photoprotective nanoemulsions

    Directory of Open Access Journals (Sweden)

    Débora Granemann e Silva

    2014-09-01

    Full Text Available New technologies that improve the physical as the sensory properties of sunscreens can help to increase its continued use and impact on health. The use of nanoemulsions in the development of photoprotective vehicles is an advantage, since nanostructured components may have superior properties regarding their performance when compared to conventional products. The advantages of using nanobiotechnology in manufacture of cosmetic and dermatological formulations arise from the protection of compounds from chemical or enzymatic degradation, from the control of their release, and also to the prolonged retention time of cosmetic ingredients in the stratum corneum. Thus, this study aimed to evaluate the impact of stirring speed and of glycerin and sodium chloride concentrations in the development and effectiveness of a nanoemulsion containing ethylhexyl methoxycinnamate and benzophenone-3. The results of statistical analyses regarding the impact of the variables in the process of nanoemulsion development showed that these parameters affect the phase inversion temperature (PIT. However, this did not affect the particle size and the photoprotective efficacy in vitro.

  12. Effect of friction stir welding speed on the microstructure and mechanical properties of a duplex stainless steel

    International Nuclear Information System (INIS)

    Saeid, T.; Abdollah-zadeh, A.; Assadi, H.; Malek Ghaini, F.

    2008-01-01

    The present study focuses on the effect of the welding speed on the microstructure and mechanical properties of the stir zone (SZ) in friction stir welding (FSW) of SAF 2205 duplex stainless steel. A single tool, made of a WC-base material, was used to weld 2 mm-thick plates at a constant rotational speed of 600 rpm. X-ray radiography revealed that sound welds were successfully obtained for the welding speeds in the range of 50-200 mm/min, whereas a groove-like defect was formed at the higher speed of 250 mm/min. Moreover, increasing the welding speed decreased the size of the α and γ grains in the SZ, and hence, improved the mean hardness value and the tensile strength of the SZ. These results are interpreted with respect to interplay between the welding speed and the peak temperature in FSW

  13. Enabling high speed friction stir welding of aluminum tailor welded blanks

    Science.gov (United States)

    Hovanski, Yuri

    Current welding technologies for production of aluminum tailor-welded blanks (TWBs) are utilized in low-volume and niche applications, and have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high-volumes. While friction stir welding (FSW) has traditionally been applied at linear velocities less than one meter per minute, high volume production applications demand the process be extended to higher velocities more amenable to cost sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low to moderate welding velocities do not directly translate to high speed linear friction stir welding. Therefore, in order to facilitate production of high volume aluminum FSW components, parameters were developed with a minimum welding velocity of three meters per minute. With an emphasis on weld quality, welded blanks were evaluated for post-weld formability using a combination of numerical and experimental methods. Evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum tailor-welded blanks, which provided validation of the numerical and experimental analysis of laboratory scale tests.

  14. Effect of tool rotational speed and penetration depth on dissimilar aluminum alloys friction stir spot welds

    Directory of Open Access Journals (Sweden)

    Joaquín M. Piccini

    2017-03-01

    Full Text Available In the last years, the automotive industry is looking for the use of aluminum parts in replace of steel parts in order to reduce the vehicles weight. These parts have to be joined, for instance, by welding processes. The more common welding process in the automotive industry is the Resistance Spot Welding (RSW technique. However, RSW of aluminum alloys has many disadvantages. Regarding this situation, a variant of the Friction Stir Welding process called Friction Stir Spot Welding (FSSW has been developed, showing a strong impact in welding of aluminum alloys and dissimilar materials in thin sheets. Process parameters affect the characteristics of the welded joints. However, the information available on this topic is scarce, particularly for dissimilar joints and thin sheets. The aim of this work was to study the effect of the rotational speed and the tool penetration depth on the characteristics of dissimilar FSS welded joints. Defects free joints have been achieved with higher mechanical properties than the ones reported. The maximum fracture load was 5800 N. It was observed that the effective joint length of the welded spots increased with the tool penetration depth, meanwhile the fracture load increased and then decreased. Finally, welding at 1200 RPM produced welded joints with lower mechanical properties than the ones achieved at 680 and 903 RPM.

  15. High-Speed Friction-Stir Welding to Enable Aluminum Tailor-Welded Blanks

    Science.gov (United States)

    Hovanski, Yuri; Upadhyay, Piyush; Carsley, John; Luzanski, Tom; Carlson, Blair; Eisenmenger, Mark; Soulami, Ayoub; Marshall, Dustin; Landino, Brandon; Hartfield-Wunsch, Susan

    2015-05-01

    Current welding technologies for production of aluminum tailor-welded blanks (TWBs) are utilized in low-volume and niche applications, and they have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high volumes. While friction-stir welding (FSW) has been traditionally applied at linear velocities less than 1 m/min, high-volume production applications demand the process be extended to higher velocities more amenable to cost-sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low-to-moderate welding velocities do not directly translate to high-speed linear FSW. Therefore, to facilitate production of high-volume aluminum FSW components, parameters were developed with a minimum welding velocity of 3 m/min. With an emphasis on weld quality, welded blanks were evaluated for postweld formability using a combination of numerical and experimental methods. An evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum TWBs, which provided validation of the numerical and experimental analysis of laboratory-scale tests.

  16. Nonlinear Time Reversal Acoustic Method of Friction Stir Weld Assessment, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of the project is demonstration of the feasibility of Friction Stir Weld (FSW) assessment by novel Nonlinear Time Reversal Acoustic (TRA) method. Time...

  17. Tool geometry, rotation and travel speeds effects on the properties of dissimilar magnesium/aluminum friction stir welded lap joints

    International Nuclear Information System (INIS)

    Mohammadi, J.; Behnamian, Y.; Mostafaei, A.; Gerlich, A.P.

    2015-01-01

    Highlights: • Tool geometry, rotation and travel speeds show great effect on the microstructure stability of FSW joint. • Increasing rotation and travel speeds resulted in increasing the tensile strength and ductility of the joints. • Better intermixing between Al/Mg alloys was obtained by tapered threaded pin. • A mechanical interlocking mechanism proposed for higher ductility and superior tensile properties in FSW joints. - Abstract: Lap joint friction stir welding (FSW) between dissimilar AZ31B and Al 6061 alloys sheets was conducted using various welding parameters including tool geometry, rotation and travel speeds. Tapered threaded pin and tapered pin tools were applied to fabricate FSW joints, using different rotation and travel speeds. Metallurgical investigations including X-ray diffraction pattern (XRD), optical microscopy images (OM), scanning electron microscopy equipped with an energy-dispersive X-ray spectroscopy (SEM–EDS) and electron probe microanalysis (EPMA) were used to characterize joints microstructures made with different welding parameters. Intermetallic phases were detected in the weld zone (WZ). Various microstructures were observed in the stir zone which can be attributed to using different travel and rotation speeds. Mechanical evaluation including lap shear fracture load test and microhardness measurements indicated that by simultaneously increasing the tool rotation and travel speeds, the joint tensile strength and ductility reached a maximum value. Microhardness studies and extracted results from stress–strain curves indicated that mechanical properties were affected by FSW process. Furthermore, phase analyses by XRD indicated the presence of intermetallic compounds in the weld zone. Finally, in the Al/Mg dissimilar weld, fractography studies showed that intermetallic compounds formation in the weld zone had an influence on the failure mode

  18. Effect of Welding Speed on Microstructure and Mechanical Properties due to The Deposition of Reinforcements on Friction Stir Welded Dissimilar Aluminium Alloys

    Directory of Open Access Journals (Sweden)

    Baridula Ravinder Reddy

    2017-01-01

    Full Text Available The strength of the welded joint obtained by solid state stir welding process was found to be improved as compared to fusion welding process. The deposition of reinforcements during friction stir welding process can further enhance the strength of the welded joint by locking the movement of grain boundaries. In the present study, the aluminium alloys AA2024 and AA7075 were welded effectively by depositing the multi-walled carbon nanotubes in to the stir zone. The mechanical properties and microstructures were studied by varying the traverse speed at constant rotational speed. The results show that rotating tool pin stirring action and heat input play an important role in controlling the grain size. The carbon nanotubes were found to be distributed uniformly at a welding speed (traverse speed of 80mm/min. This enhanced the mechanical properties of the welded joint. The microstructure and Electron dispersive X-ray analysis (EDX studies indicate that the deposition of carbon nanotubes in the stir zone was influenced by the traverse speed.

  19. Modeling of mixing in stirred bioreactors 4. mixing time for aerated bacteria, yeasts and fungus broths

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    Cascaval Dan

    2004-01-01

    Full Text Available The mixing time for bioreactors depends mainly on the rheoiogicai properties of the broths, the biomass concentration and morphology, mixing system characteristics and fermentation conditions. For quantifying the influence of these factors on the mixing efficiency for stirred bioreactors, aerated broths of bacteria (P. shermanii, yeasts (S. cerevisiae and fungi (P. chrysogenum, free mycelia and mycelial aggregates of different concentrations have been investigated using a laboratory bioreactor with a double turbine impeller. The experimental data indicated that the influence of the rotation speed, aeration rate and stirrer positions on the mixing intensity strongly differ from one system to another and must be correlated with the microorganism characteristics, namely: the biomass concentration and morphology. Moreover, compared with non-aerated broths, variations of the mixing time with the considered parameters are very different, due to the complex flow mechanism of gas-liquid dispersions. By means of the experimental data and using a multiregression analysis method some mathematical correlations for the mixing time of the general form: tm = a1*Cx2+a2*Cx+a3*IgVa+a4-N2+a5-N+a6/a7*L2+a8*L+a9 were established. The proposed equations offer good agreement with the experiments, the average deviation being ±6.7% - ±9.4 and are adequate for the flow regime Re < 25,000.

  20. The Effect of Temperature and Rotational Speed on Structure and Mechanical Properties of Cast Cu Base Alloy (Cu-Al-Si-Fe) Welded by Semisolid Stir Joining Method

    Science.gov (United States)

    Ferasat, Keyvan; Aashuri, Hossein; Kokabi, Amir Hossein; Shafizadeh, Mahdi; Nikzad, Siamak

    2015-12-01

    Semisolid stir joining has been under deliberation as a possible method for joining of copper alloys. In this study, the effect of temperature and rotational speed of stirrer on macrostructure evaluation and mechanical properties of samples were investigated. Optical microscopy and X-ray diffraction were performed for macro and microstructural analysis. A uniform micro-hardness profile was attained by semisolid stir joining method. The ultimate shear strength and bending strength of welded samples were improved in comparison with the cast sample. There is also lower area porosity in welded samples than the cast metal. The mechanical properties were improved by increasing temperature and rotational speed of the joining process.

  1. Influence of tool geometry and rotational speed on mechanical properties and defect formation in friction stir lap welded 5456 aluminum alloy sheets

    International Nuclear Information System (INIS)

    Salari, Emad; Jahazi, Mohammad; Khodabandeh, Alireza; Ghasemi-Nanesa, Hadi

    2014-01-01

    Highlights: • Successful lap joint friction stir welding of AA5456 with two different tempers. • New stepped conical threaded pin for FSW of lap joints is introduced. • Investigated interactions between tool geometry and mechanical properties. • Microstructure and fracture surface analysis of dissimilar lap welds. - Abstract: Friction stir welding of AA5456 aluminum alloy in lap joint configuration is with two different tempers, T321 and O, and different thicknesses, 5 mm and 2.5 mm was investigated. The influences of tool geometry and various rotational speeds on macrostructure, microstructure and joint strength are presented. Specifically, four different tool pin profiles (a conical thread pin, a cylindrical–conical thread pin, a stepped conical thread pin and Flared Triflute pin tool) and two rotational speeds, 600 and 800 rpm, were used. The results indicated that, tool geometry influences significantly material flow in the nugget zone and accordingly control the weld mechanical properties. Of particular interest is the stepped conical threaded pin, which is introduced for the first time in the present investigation. Scanning electron microscopy investigation of the fracture location of samples was carried out and the findings correlated with tool geometry features and their influences on material flow and tension test results. The optimum microstructure and mechanical properties were obtained for the joints produced with the stepped conical thread pin profile and rotational speed of 600 rpm. The characteristics of the nugget zone microstructure, hooking height, and fracture location of the weld joints were used as criteria to quantify the influence of processing conditions on joint performance and integrity. The results are interpreted in the framework of physical metallurgy properties and compared with published literature

  2. High-Speed Friction Stir Welding of AA7075-T6 Sheet: Microstructure, Mechanical Properties, Micro-texture, and Thermal History

    Science.gov (United States)

    Zhang, Jingyi; Upadhyay, Piyush; Hovanski, Yuri; Field, David P.

    2018-01-01

    Friction stir welding (FSW) is a cost-effective and high-quality joining process for aluminum alloys (especially heat-treatable alloys) that is historically operated at lower joining speeds (up to hundreds of millimeters per minute). In this study, we present a microstructural analysis of friction stir welded AA7075-T6 blanks with high welding speeds up to 3 M/min. Textures, microstructures, mechanical properties, and weld quality are analyzed using TEM, EBSD, metallographic imaging, and Vickers hardness. The higher welding speed results in narrower, stronger heat-affected zones (HAZs) and also higher hardness in the nugget zones. The material flow direction in the nugget zone is found to be leaning towards the welding direction as the welding speed increases. Results are coupled with welding parameters and thermal history to aid in the understanding of the complex material flow and texture gradients within the welds in an effort to optimize welding parameters for high-speed processing.

  3. Mechanical Properties and Wear Behavior of AA5182/WC Nanocomposite Fabricated by Friction Stir Welding at Different Tool Traverse Speeds

    Science.gov (United States)

    Paidar, Moslem; Asgari, Ali; Ojo, Olatunji Oladimeji; Saberi, Abbas

    2018-03-01

    Grain growth inhibition at the heat-affected zone, improved weld strength and superior tribological properties of welds are desirable attributes of modern manufacturing. With the focused on these attributes, tungsten carbide (WC) nanoparticles were employed as reinforcements for the friction stir welding of 5-mm-thick AA5182 aluminum alloy by varying tool traverse speeds. The microstructure, microhardness, ultimate tensile strength, fracture and wear behavior of the resultant WC-reinforced welds were investigated, while unreinforced AA5182 welds were employed as controls for the study. The result shows that the addition of WC nanoparticles causes substantial grain refinement within the weld nugget. A decrease in traverse speed caused additional particle fragmentation, improved hardness value and enhanced weld strength in the reinforced welds. Improved wear rate and friction coefficient of welds were attained at a reduced traverse speed of 100 mm/min in the WC-reinforced welds. This improvement is attributed to the effects of reduced grain size/grain fragmentation and homogeneous dispersion of WC nanoparticles within the WC-reinforced weld nugget.

  4. Speed scaling for weighted flow time

    NARCIS (Netherlands)

    Bansal, N.; Pruhs, K.R.; Stein, C.

    2007-01-01

    In addition to the traditional goal of efficiently managing time and space, many computers now need to efficiently manage power usage. For example, Intel's SpeedStep and AMD's PowerNOW technologies allow the Windows XP operating system to dynamically change the speed of the processor to prolong

  5. Stirring inertia in time-dependent low Reynolds number flows

    Science.gov (United States)

    Yecko, Philip; Luchtenburg, Dirk Martin (Mark); Forgoston, Eric; Billings, Lora

    2017-11-01

    Diagnosis of a kinematic flow and its transport using Lagrangian coherent structures (LCS) based on finite-time Lyapunov exponents (FTLE) neglects dynamical effects, such as pressure, as well as dynamically important constraints, such as potential vorticity conservation. Chaotic advection, on the other hand, often neglects inertial effects, which are prominent in LCS. We present results for very low Reynolds number laboratory flows, including a Stokes double gyre, vertically sheared strain and a four roll mill. Images of tracer (dye) and FTLE fields computed from particle image velocimetry (PIV) reveal complementary sets of flow structures, giving a more complete picture of transport in these flows. We confirm by computing FTLE of an exact time-dependent Stokes flow solution and present implications of these findings for inertial object transport in flows. Support of NSF DMS-1418956 is gratefully acknoweldged.

  6. Effect of tool rotational speed on force generation, microstructure and mechanical properties of friction stir welded Al–Mg–Cr–Mn (AA 5052-O) alloy

    International Nuclear Information System (INIS)

    Moshwan, Raza; Yusof, Farazila; Hassan, M.A.; Rahmat, S.M.

    2015-01-01

    Highlights: • 3 mm thick AA 5052-O alloy plates were successfully joined by FSW process. • The joint was produced at 1000 rpm yielded a maximum tensile strength of 132 MPa. • The dissolution of β-Mg 2 Al 3 intermetallic phases of FSWed joints were reported. • Different axial forces acted on welding tool during welding were investigated. - Abstract: Friction stir welding (FSW) between 3 mm thick AA 5052-O aluminum alloy plates was investigated in the present study. Different welded specimens were produced by employing a constant tool traverse speed of 120 mm/min and by varying rotating speeds from 800 to 3000 rpm. The welded joints were characterized by its appearances, microstructural and mechanical properties at room temperature. The measurement of different forces acted on the tool during the FSW of AA 5052-O plates provided a significant insight to determine the quality of the welded joints. From the appearances of the welded joints it was evident that, except the tool rotational speed of 3000 rpm all other rotational speeds produced sound welded joints with smooth surface. The joint produced at 1000 rpm yielded a maximum tensile strength of 132 MPa which was 74% of the base material strength. Field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS) analyses on the stir zone suggested that, β-Mg 2 Al 3 intermetallic phases of the base material were mechanically fractured, smeared and mixed to different geometries due to tool stirring. The dissolution and redistribution of β-Mg 2 Al 3 second phase particles in the stir zone had a considerable effect on the reduction of the tensile strength of the welded joints. The reduction in hardness at the nugget zone (NZ) of the welded joints under different tool rotational speeds could be attributed to the dislocation of Mg-rich phases and segregation of Mg solute atoms at grain boundaries, which drew solute Mg atoms away from the α-aluminum matrix

  7. Effect of welding parameters (plunge depths of shoulder, pin geometry, and tool rotational speed) on the failure mode and stir zone characteristics of friction stir spot welded aluminum 2024-T3 sheets

    Energy Technology Data Exchange (ETDEWEB)

    Paidar, Moslem; Sarab, Mahsa Lali; Taheri, Morteza; Khodabandeh, Alireza [Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2015-11-15

    The main purpose of this study was to investigate the effect of welding parameters on the failure mode and stir zone characteristics of aluminum alloy 2024-T3 joined by friction stir spot welding. The welding parameters in this work are tool rotational speed, plunge depths of shoulder, and pin geometry. In accordance with the methods of previous investigations, the rotational speeds were set to 630 rpm to 2000 rpm. Two pin geometries with concave shoulder were used: triangular and cylindrical. The plunge depths of the shoulder were 0.3, 0.5 and 0.7 mm. The shoulder diameter and pin height for both geometries were 14 and 2.4 mm, respectively. The diameter of the cylindrical and triangular pins was 5 mm. Results show that the parameters mentioned earlier influence fracture mode under tension shear loading. Two different fracture modes were observed during the examinations. Low-penetration depths and low-rotational speeds lead to shear fracture, whereas high values of these factors cause the tension-shear fracture mode. Fracture of the lower sheet sometimes occurs at high rotational speeds.

  8. High-Speed Friction Stir Welding of AA7075-T6 Sheet: Microstructure, Mechanical Properties, Micro-texture, and Thermal History

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jingyi; Upadhyay, Piyush; Hovanski, Yuri; Field, David P.

    2017-11-20

    Friction-stir-welding (FSW) is a cost-effective and high quality joining process for aluminum alloys (especially heat-treatable allo ys) that has been applied successfully in the aerospace industry. However, the full potential of FSW on more cost-sensitive applications is still limited by the production rate, namely the welding speed of the process. The majority of literature evaluating FSW of aluminum alloys is based on welds made in the range of welding speeds around hundreds of millimeters per minute, and only a handful are at a moderate speed of 1 m/min. In this study we present a microstructural analysis of friction stir welded AA7075-T6 blanks with welding speeds up to 3 m/min. Textures, microstructures, mechanical properties, and weld quality are analyzed using TEM, EBSD, metallographic imaging, and Vickers hardness. Results are coupled with welding parameters to aid in the understanding of the complex material flow and texture gradients within the welds in an effort to optimize welding parameters for high speed processing.

  9. Time optimal paths for high speed maneuvering

    Energy Technology Data Exchange (ETDEWEB)

    Reister, D.B.; Lenhart, S.M.

    1993-01-01

    Recent theoretical results have completely solved the problem of determining the minimum length path for a vehicle with a minimum turning radius moving from an initial configuration to a final configuration. Time optimal paths for a constant speed vehicle are a subset of the minimum length paths. This paper uses the Pontryagin maximum principle to find time optimal paths for a constant speed vehicle. The time optimal paths consist of sequences of axes of circles and straight lines. The maximum principle introduces concepts (dual variables, bang-bang solutions, singular solutions, and transversality conditions) that provide important insight into the nature of the time optimal paths. We explore the properties of the optimal paths and present some experimental results for a mobile robot following an optimal path.

  10. REAL TIME SPEED ESTIMATION FROM MONOCULAR VIDEO

    Directory of Open Access Journals (Sweden)

    M. S. Temiz

    2012-07-01

    Full Text Available In this paper, detailed studies have been performed for developing a real time system to be used for surveillance of the traffic flow by using monocular video cameras to find speeds of the vehicles for secure travelling are presented. We assume that the studied road segment is planar and straight, the camera is tilted downward a bridge and the length of one line segment in the image is known. In order to estimate the speed of a moving vehicle from a video camera, rectification of video images is performed to eliminate the perspective effects and then the interest region namely the ROI is determined for tracking the vehicles. Velocity vectors of a sufficient number of reference points are identified on the image of the vehicle from each video frame. For this purpose sufficient number of points from the vehicle is selected, and these points must be accurately tracked on at least two successive video frames. In the second step, by using the displacement vectors of the tracked points and passed time, the velocity vectors of those points are computed. Computed velocity vectors are defined in the video image coordinate system and displacement vectors are measured by the means of pixel units. Then the magnitudes of the computed vectors in the image space are transformed to the object space to find the absolute values of these magnitudes. The accuracy of the estimated speed is approximately ±1 – 2 km/h. In order to solve the real time speed estimation problem, the authors have written a software system in C++ programming language. This software system has been used for all of the computations and test applications.

  11. Shear rate analysis of water dynamic in the continuous stirred tank

    Science.gov (United States)

    Tulus; Mardiningsih; Sawaluddin; Sitompul, O. S.; Ihsan, A. K. A. M.

    2018-02-01

    Analysis of mixture in a continuous stirred tank reactor (CSTR) is an important part in some process of biogas production. This paper is a preliminary study of fluid dynamic phenomenon in a continuous stirred tank numerically. The tank is designed in the form of cylindrical tank equipped with a stirrer. In this study, it is considered that the tank is filled with water. Stirring is done with a stirring speed of 10rpm, 15rpm, 20rpm, and 25rpm. Mathematical modeling of stirred tank is derived. The model is calculated by using the finite element method that are calculated using CFD software. The result shows that the shear rate is high on the front end portion of the stirrer. The maximum shear rate tend to a stable behaviour after the stirring time of 2 second. The relation between the speed and the maximum shear rate is in the form of linear equation.

  12. Influence of the stirring time on the exfoliation of the Cloisite 30 B clay in PVC composite: structural characterization by XRD

    International Nuclear Information System (INIS)

    Cabral, Andreia M.V.; Rodrigues, Meiry G.F.

    2009-01-01

    This study aims to evaluate the influence of the stirring time on the exfoliation efficiency of the montmorillonite clay in PVC composites, prepared by the polymerization 'in situ' process. The work was performed in 2 steps. In first stage: tests of expansion with Cloisite 30B clay in MVC, which was used to assess the degree of expansion in MVC of each of them at different stirring times: 2, 4 and 6 h. After stirring, each system was kept in observation for 3 days to evaluate the changes in the decanted volume of the clay in the reactor. Second stage: the Influence of the stirring time for the clay exfoliation. Cloisite 30B clay was used to compare the influence of the stirring time for exfoliation and characterized by X-ray diffraction (XRD). (author)

  13. Effect of Thread and Rotating Speed on Material Flow Behavior and Mechanical Properties of Friction Stir Lap Welding Joints

    Science.gov (United States)

    Ji, Shude; Li, Zhengwei; Zhou, Zhenlu; Wu, Baosheng

    2017-10-01

    This study focused on the effects of thread on hook and cold lap formation, lap shear property and impact toughness of alclad 2024-T4 friction stir lap welding (FSLW) joints. Except the traditional threaded pin tool (TR-tool), three new tools with different thread locations and orientations were designed. Results showed that thread significantly affected hook, cold lap morphologies and lap shear properties. The tool with tip-threaded pin (T-tool) fabricated joint with flat hook and cold lap, which resulted in shear fracture mode. The tools with bottom-threaded pin (B-tool) eliminated the hook. The tool with reverse-threaded pin (R-tool) widened the stir zone width. When using configuration A, the joints fabricated by the three new tools showed higher failure loads than the joint fabricated by the TR-tool. The joint using the T-tool owned the optimum impact toughness. This study demonstrated the significance of thread during FSLW and provided a reference to optimize tool geometry.

  14. Influence of Tool Rotational Speed and Post-Weld Heat Treatments on Friction Stir Welded Reduced Activation Ferritic-Martensitic Steel

    Science.gov (United States)

    Manugula, Vijaya L.; Rajulapati, Koteswararao V.; Reddy, G. Madhusudhan; Mythili, R.; Bhanu Sankara Rao, K.

    2017-08-01

    The effects of tool rotational speed (200 and 700 rpm) on evolving microstructure during friction stir welding (FSW) of a reduced activation ferritic-martensitic steel (RAFMS) in the stir zone (SZ), thermo-mechanically affected zone (TMAZ), and heat-affected zone (HAZ) have been explored in detail. The influence of post-weld direct tempering (PWDT: 1033 K (760 °C)/ 90 minutes + air cooling) and post-weld normalizing and tempering (PWNT: 1253 K (980 °C)/30 minutes + air cooling + tempering 1033 K (760 °C)/90 minutes + air cooling) treatments on microstructure and mechanical properties has also been assessed. The base metal (BM) microstructure was tempered martensite comprising Cr-rich M23C6 on prior austenite grain and lath boundaries with intra-lath precipitation of V- and Ta-rich MC precipitates. The tool rotational speed exerted profound influence on evolving microstructure in SZ, TMAZ, and HAZ in the as-welded and post-weld heat-treated states. Very high proportion of prior austenitic grains and martensite lath boundaries in SZ and TMAZ in the as-welded state showed lack of strengthening precipitates, though very high hardness was recorded in SZ irrespective of the tool speed. Very fine-needle-like Fe3C precipitates were found at both the rotational speeds in SZ. The Fe3C was dissolved and fresh precipitation of strengthening precipitates occurred on both prior austenite grain and sub-grain boundaries in SZ during PWNT and PWDT. The post-weld direct tempering caused coarsening and coalescence of strengthening precipitates, in both matrix and grain boundary regions of TMAZ and HAZ, which led to inhomogeneous distribution of hardness across the weld joint. The PWNT heat treatment has shown fresh precipitation of M23C6 on lath and grain boundaries and very fine V-rich MC precipitates in the intragranular regions, which is very much similar to that prevailed in BM prior to FSW. Both the PWDT and PWNT treatments caused considerable reduction in the hardness of SZ

  15. In-process tool rotational speed variation with constant heat input in friction stir welding of AZ31 sheets with variable thickness

    Science.gov (United States)

    Buffa, Gianluca; Campanella, Davide; Forcellese, Archimede; Fratini, Livan; Simoncini, Michela

    2017-10-01

    In the present work, friction stir welding experiments on AZ31 magnesium alloy sheets, characterized by a variable thickness along the welding line, were carried out. The approach adapted during welding consisted in maintaining constant the heat input to the joint. To this purpose, the rotational speed of the pin tool was increased with decreasing thickness and decreased with increasing thickness in order to obtain the same temperatures during welding. The amount by which the rotational speed was changed as a function of the sheet thickness was defined on the basis of the results given by FEM simulations of the FSW process. Finally, the effect of the in-process variation of the tool rotational speed on the mechanical and microstructural properties of FSWed joints was analysed by comparing both the nominal stress vs. nominal strain curves and microstructure of FSWed joints obtained in different process conditions. It was observed that FSW performed by keeping constant the heat input to the joint leads to almost coincident results both in terms of the curve shape, ultimate tensile strength and ultimate elongation values, and microstructure.

  16. Spray nozzles, pressures, additives and stirring time on viability and pathogenicity of entomopathogenic nematodes (nematoda: rhabditida) for greenhouses.

    Science.gov (United States)

    Moreira, Grazielle Furtado; Batista, Elder Simões de Paula; Campos, Henrique Borges Neves; Lemos, Raphael Emilio; Ferreira, Marcelo da Costa

    2013-01-01

    The objective of this study was to evaluate different strategies for the application of entomopathogenic nematodes (EPN). Three different models of spray nozzles with air induction (AI 11003, TTI 11003 and AD-IA 11004), three spray pressures (207, 413 and 720 kPa), four different additives for tank mixtures (cane molasses, mineral oil, vegetable oil and glycerin) and the influence of tank mixture stirring time were all evaluated for their effect on EPN (Steinernema feltiae) viability and pathogenicity. The different nozzles, at pressures of up to 620 kPa, were found to be compatible with S. feltiae. Vegetable oil, mineral oil and molasses were found to be compatible adjuvants for S. feltiae, and stirring in a motorized backpack sprayer for 30 minutes did not impact the viability or pathogenicity of this nematode. Appropriate techniques for the application of nematodes with backpack sprayers are discussed.

  17. Effect of the Preheating Temperature on Process Time in Friction Stir Welding of Al 6061-T6

    DEFF Research Database (Denmark)

    Jabbari, Masoud

    2013-01-01

    This paper presents the results obtained and the deductions made from an analytical modeling involving friction stir welding of Al 6061-T6. A new database was developed to simulate the contact temperature between the tool and the workpiece. A second-order equation is proposed for simulating...... the temperature in the contact boundary and the thermal history during the plunge phase. The effect of the preheating temperature on the process time was investigated with the proposed model. The results show that an increase of the preheating time leads to a decrease in the process time up to the plunge...

  18. Analysis of lime-slurry stirred tank carbonation reactor

    International Nuclear Information System (INIS)

    McAleese, J.P.; Belt, B.A.; Datesh, J.R.; Shaeffer, M.C.

    1977-01-01

    Gas residence time distributions were determined for a stirred tank carbonation reactor. Empirical correlations for the first and second moments of the residence time distribution (RTD) curves as functions of flow rates and impeller speeds were obtained. Decontamination factors for 85 Kr were measured

  19. Generate stepper motor linear speed profile in real time

    Science.gov (United States)

    Stoychitch, M. Y.

    2018-01-01

    In this paper we consider the problem of realization of linear speed profile of stepper motors in real time. We considered the general case when changes of speed in the phases of acceleration and deceleration are different. The new and practical algorithm of the trajectory planning is given. The algorithms of the real time speed control which are suitable for realization to the microcontroller and FPGA circuits are proposed. The practical realization one of these algorithms, using Arduino platform, is given also.

  20. Stochastic generation of hourly wind speed time series

    International Nuclear Information System (INIS)

    Shamshad, A.; Wan Mohd Ali Wan Hussin; Bawadi, M.A.; Mohd Sanusi, S.A.

    2006-01-01

    In the present study hourly wind speed data of Kuala Terengganu in Peninsular Malaysia are simulated by using transition matrix approach of Markovian process. The wind speed time series is divided into various states based on certain criteria. The next wind speed states are selected based on the previous states. The cumulative probability transition matrix has been formed in which each row ends with 1. Using the uniform random numbers between 0 and 1, a series of future states is generated. These states have been converted to the corresponding wind speed values using another uniform random number generator. The accuracy of the model has been determined by comparing the statistical characteristics such as average, standard deviation, root mean square error, probability density function and autocorrelation function of the generated data to those of the original data. The generated wind speed time series data is capable to preserve the wind speed characteristics of the observed data

  1. Influence of the welding temperature and the welding speed on the mechanical properties of friction stir welds in EN AW-2219-T87

    Science.gov (United States)

    Bachmann, A.; Krutzlinger, M.; Zaeh, M. F.

    2018-06-01

    Friction Stir Welding (FSW) is an innovative joining technique, which has proven to produce high quality joints in high strength aluminum alloys. Consequently, it is commonly used to manufacture lightweight aerospace structures with stringent requirements. For these structures, it is necessary to ensure a high ultimate tensile strength (UTS). Various studies have reported that the UTS is significantly influenced by the welding parameters. Samples welded with different parameter sets showed a considerably different UTS, despite being free from detectable welding defects (e.g. tunnel defect, voids, or lack of penetration). Based on the observations in the literature, a hypothesis was posed. The welding temperature along with the welding speed determine the UTS of the weld. This study aims to prove this hypothesis experimentally by using temperature-controlled FSW to join plates of EN AW-2219-T87 in butt joint configuration. The welded samples were examined using visual inspection, metallography, X-ray imaging, and uniaxial tensile tests. Finally, a statistical analysis was conducted. Hereby, the hypothesis was confirmed.

  2. High-speed optical signal processing using time lenses

    DEFF Research Database (Denmark)

    Galili, Michael; Hu, Hao; Guan, Pengyu

    2015-01-01

    This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle.......This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle....

  3. Towards real-time feedback in high performance speed skating

    NARCIS (Netherlands)

    van der Eb, Jeroen; Zandee, Willem; van den Bogaard, Timo; Geraets, Sjoerd; Veeger, H.E.J.; Beek, Peter; Potthast, Wolfgang; Niehoff, Anja; David, Sina

    2017-01-01

    The aim of the current study is to evaluate several performance indicators to be used as real-time feedback in the coming experiments to enhance performance of elite speeds skaters. Six speed skaters, wearing one IMU per skate, collected data over one full training season to evaluate and pinpoint

  4. Speeding Up Network Simulations Using Discrete Time

    OpenAIRE

    Lucas, Aaron; Armbruster, Benjamin

    2013-01-01

    We develop a way of simulating disease spread in networks faster at the cost of some accuracy. Instead of a discrete event simulation (DES) we use a discrete time simulation. This aggregates events into time periods. We prove a bound on the accuracy attained. We also discuss the choice of step size and do an analytical comparison of the computational costs. Our error bound concept comes from the theory of numerical methods for SDEs and the basic proof structure comes from the theory of numeri...

  5. Effect of Fluidized Bed Stirring on Drying Process of Adhesive Particles

    Directory of Open Access Journals (Sweden)

    P. Hoffman

    2017-04-01

    Full Text Available This paper presents an attempt to optimize fluidized bed drying of wet and adhesive particles (with an initial diameter of about 580 mm with the use of stirring, and discusses the influence of stirring on the total drying time. The goal was to demonstrate the positive effect of stirring a fluidized bed to the drying time, to find the optimal parameters (stirrer design, speed, and size. Experiments were conducted on a drying chamber in batch operation. The objective was to evaluate the effect of stirring on the total drying time. The drying chambers were 85 mm, 100 mm, and 140 mm in diameter. An optimal stirrer shape and speed were specified. Our arrangement of the fluidized bed resulted in a decrease in drying time by up to 40 %.

  6. Time-limited optimal dynamics beyond the Quantum Speed Limit

    DEFF Research Database (Denmark)

    Gajdacz, Miroslav; Das, Kunal K.; Arlt, Jan

    2015-01-01

    The quantum speed limit sets the minimum time required to transfer a quantum system completely into a given target state. At shorter times the higher operation speed has to be paid with a loss of fidelity. Here we quantify the trade-off between the fidelity and the duration in a system driven......-off expressed in terms of the direct Hilbert velocity provides a robust prediction of the quantum speed limit and allows to adapt the control optimization such that it yields a predefined fidelity. The results are verified numerically in a multilevel system with a constrained Hamiltonian, and a classification...

  7. Walking speed-related changes in stride time variability: effects of decreased speed

    Directory of Open Access Journals (Sweden)

    Dubost Veronique

    2009-08-01

    Full Text Available Abstract Background Conflicting results have been reported regarding the relationship between stride time variability (STV and walking speed. While some studies failed to establish any relationship, others reported either a linear or a non-linear relationship. We therefore sought to determine the extent to which decrease in self-selected walking speed influenced STV among healthy young adults. Methods The mean value, the standard deviation and the coefficient of variation of stride time, as well as the mean value of stride velocity were recorded while steady-state walking using the GAITRite® system in 29 healthy young adults who walked consecutively at 88%, 79%, 71%, 64%, 58%, 53%, 46% and 39% of their preferred walking speed. Results The decrease in stride velocity increased significantly mean values, SD and CoV of stride time (p Conclusion The results support the assumption that gait variability increases while walking speed decreases and, thus, gait might be more unstable when healthy subjects walk slower compared with their preferred walking speed. Furthermore, these results highlight that a decrease in walking speed can be a potential confounder while evaluating STV.

  8. The Influence of Extractant TOA, Stirring Time on the Extraction ProcessLiquid-liquid, and Liquid Membrane on the Liquid Wastes Containing Cd

    International Nuclear Information System (INIS)

    Prayitno; Djoko-Sardjono; Nurimaniwati; Adhe-Helmayani

    2000-01-01

    The influence of extractant and stirring time on the reduction componentcadmium on liquid wastes has been investigated. The method of experimentalused the extraction with liquid membrane emulsion. The parameters to beinvestigated were extractant amount tri-n octylamine (TOA), duration ofstirring time. In this investigated, extractant amount was varied from 5 to25 % (v/v) TOA, duration of stirring time varied from 5 to minutes. Theresult of experimental can be concluded that the best condition obtained forreducing cadmium component was on extractant amount 20 % (v/v) TOA, stirringtime 25 minutes. The best condition for reducing the cadmium component wasefficiency factor 98.35%. (author)

  9. Engine control system having speed-based timing

    Science.gov (United States)

    Willi, Martin L [Dunlap, IL; Fiveland, Scott B [Metamora, IL; Montgomery, David T [Edelstein, IL; Gong, Weidong [Dunlap, IL

    2012-02-14

    A control system for an engine having a cylinder is disclosed having an engine valve movable to regulate a fluid flow of the cylinder and an actuator associated with the engine valve. The control system also has a controller in communication with the actuator. The controller is configured to receive a signal indicative of engine speed and compare the engine speed signal with a desired engine speed. The controller is also configured to selectively regulate the actuator to adjust a timing of the engine valve to control an amount of air/fuel mixture delivered to the cylinder based on the comparison.

  10. Fat suppression with short inversion time inversion-recovery and chemical-shift selective saturation: a dual STIR-CHESS combination prepulse for turbo spin echo pulse sequences.

    Science.gov (United States)

    Tanabe, Koji; Nishikawa, Keiichi; Sano, Tsukasa; Sakai, Osamu; Jara, Hernán

    2010-05-01

    To test a newly developed fat suppression magnetic resonance imaging (MRI) prepulse that synergistically uses the principles of fat suppression via inversion recovery (STIR) and spectral fat saturation (CHESS), relative to pure CHESS and STIR. This new technique is termed dual fat suppression (Dual-FS). To determine if Dual-FS could be chemically specific for fat, the phantom consisted of the fat-mimicking NiCl(2) aqueous solution, porcine fat, porcine muscle, and water was imaged with the three fat-suppression techniques. For Dual-FS and STIR, several inversion times were used. Signal intensities of each image obtained with each technique were compared. To determine if Dual-FS could be robust to magnetic field inhomogeneities, the phantom consisting of different NiCl(2) aqueous solutions, porcine fat, porcine muscle, and water was imaged with Dual-FS and CHESS at the several off-resonance frequencies. To compare fat suppression efficiency in vivo, 10 volunteer subjects were also imaged with the three fat-suppression techniques. Dual-FS could suppress fat sufficiently within the inversion time of 110-140 msec, thus enabling differentiation between fat and fat-mimicking aqueous structures. Dual-FS was as robust to magnetic field inhomogeneities as STIR and less vulnerable than CHESS. The same results for fat suppression were obtained in volunteers. The Dual-FS-STIR-CHESS is an alternative and promising fat suppression technique for turbo spin echo MRI. Copyright 2010 Wiley-Liss, Inc.

  11. Value of time: Speeding behavior and gasoline prices

    OpenAIRE

    Wolff, Hendrik

    2012-01-01

    Do drivers reduce speeds when gasoline prices are high? Previous research investigating this energy conservation hypothesis produced mixed results. We take a fresh look at the data and estimate a significant negative relationship between speeding and gasoline prices. This presents a new methodology of deriving the 'Value of Time' (VOT) based on the intensive margin (previous VOT studies compare across the extensive margin) which has important advantages to circumvent potential omitted variabl...

  12. Effect of water-cooling treatment times on properties of friction stir welded joints of 7N01-T4 aluminum alloy

    Science.gov (United States)

    Zhang, T. H.; Wang, Y.; Fang, X. F.; Liang, P.; Zhao, Y.; Li, Y. H.; Liu, X. M.

    2018-02-01

    Due to the deformation caused by residual stress in the welding process, welded components need treatment to reduce welding distortion. In this paper, several different times of flame-heating and water-cooling treatment were subjected to the friction stir welding joints of 15mm thick 7N01P-T4 aluminum alloy sheets to study the microstructure variation of friction stir welding joints of 7N01P-T4 aluminum alloy, and to analyze the effect on micro-hardness, tensile and fracture mechanical properties. This investigation will be helpful to optimize treatment methods and provide instruction on industrial production.

  13. Magneto-optical system for high speed real time imaging

    Science.gov (United States)

    Baziljevich, M.; Barness, D.; Sinvani, M.; Perel, E.; Shaulov, A.; Yeshurun, Y.

    2012-08-01

    A new magneto-optical system has been developed to expand the range of high speed real time magneto-optical imaging. A special source for the external magnetic field has also been designed, using a pump solenoid to rapidly excite the field coil. Together with careful modifications of the cryostat, to reduce eddy currents, ramping rates reaching 3000 T/s have been achieved. Using a powerful laser as the light source, a custom designed optical assembly, and a high speed digital camera, real time imaging rates up to 30 000 frames per seconds have been demonstrated.

  14. Stirring turbulence with turbulence

    NARCIS (Netherlands)

    Cekli, H.E.; Joosten, R.; van de Water, W.

    2015-01-01

    We stir wind-tunnel turbulence with an active grid that consists of rods with attached vanes. The time-varying angle of these rods is controlled by random numbers. We study the response of turbulence on the statistical properties of these random numbers. The random numbers are generated by the

  15. Time resolution performance studies of contemporary high speed photomultipliers

    International Nuclear Information System (INIS)

    Leskovar, B.; Lo, C.C.

    1978-01-01

    The time resolution capabilities of prototype microchannel plate and static crossed-field photomultipliers have been investigated. Measurements were made of electron transit time, rise time, time response, single phtoelectron time spread and multiphotoelectron time spread for LEP HR350 proximity focused high gain curved microchannel plate and VPM-154A/1.6L static crossed-field photomultipliers. The experimental data have been compared with results obtained with conventionally designed high speed photomultipliers. Descriptions are given of both the measuring techniques and the measuring systems. 16 refs

  16. Time resolution performance studies of contemporary high speed photomultipliers

    International Nuclear Information System (INIS)

    Leskovar, B.; Lo, C.C.

    1977-01-01

    The time resolution capabilities of prototype microchannel plate and static crossed-field photomultipliers have been investigated. Measurements were made of electron transit time, rise time, time response, single photoelectron time spread and multiphotoelectron time spread for LEP HR350 proximity focused high gain curved microchannel plate and VPM-154A/1.6L static crossed-field photomultipliers. The experimental data have been compared with results obtained with conventionally designed RCS 8850 and C31024 high speed photomultipliers. Descriptions are given of both the measuring techniques and the measuring systems

  17. Projected space-time and varying speed of light

    International Nuclear Information System (INIS)

    Iovane, G.; Bellucci, S.; Benedetto, E.

    2008-01-01

    In this paper starting from El Naschie's Cantorian space-time and our model of projected Universe, we consider its properties in connection with varying speed of light. A possible way-out of the related problem is provided by the Fantappie group approach

  18. Limits on the speed of gravitational waves from pulsar timing

    International Nuclear Information System (INIS)

    Baskaran, D.; Polnarev, A. G.; Pshirkov, M. S.; Postnov, K. A.

    2008-01-01

    In this work, analyzing the propagation of electromagnetic waves in the field of gravitational waves, we show the presence and significance of the so-called surfing effect for pulsar timing measurements. It is shown that, due to the transverse nature of gravitational waves, the surfing effect leads to enormous pulsar timing residuals if the speed of gravitational waves is smaller than the speed of light. This fact allows one to place significant constraints on parameter ε, which characterizes the relative deviation of the speed of gravitational waves from the speed of light. We show that the existing constraints from pulsar timing measurements already place stringent limits on ε and consequently on the mass of the graviton m g . The limits on m g -24 are 2 orders of magnitude stronger than the current constraints from Solar System tests. The current constraints also allow one to rule out massive gravitons as possible candidates for cold dark matter in the galactic halo. In the near future, the gravitational wave background from extragalactic super massive black hole binaries, along with the expected submicrosecond pulsar timing accuracy, will allow one to achieve constraints of ε < or approx. 0.4% and possibly stronger.

  19. Development of time sensitivity and information processing speed.

    Directory of Open Access Journals (Sweden)

    Sylvie Droit-Volet

    Full Text Available The aim of this study was to examine whether age-related changes in the speed of information processing are the best predictors of the increase in sensitivity to time throughout childhood. Children aged 5 and 8 years old, as well adults, were given two temporal bisection tasks, one with short (0.5/1-s and the other with longer (4/8-s anchor durations. In addition, the participants' scores on different neuropsychological tests assessing both information processing speed and other dimensions of cognitive control (short-term memory, working memory, selective attention were calculated. The results showed that the best predictor of individual variances in sensitivity to time was information processing speed, although working memory also accounted for some of the individual differences in time sensitivity, albeit to a lesser extent. In sum, the faster the information processing speed of the participants, the higher their sensitivity to time was. These results are discussed in the light of the idea that the development of temporal capacities has its roots in the maturation of the dynamic functioning of the brain.

  20. Inattentional blindness is influenced by exposure time not motion speed.

    Science.gov (United States)

    Kreitz, Carina; Furley, Philip; Memmert, Daniel

    2016-01-01

    Inattentional blindness is a striking phenomenon in which a salient object within the visual field goes unnoticed because it is unexpected, and attention is focused elsewhere. Several attributes of the unexpected object, such as size and animacy, have been shown to influence the probability of inattentional blindness. At present it is unclear whether or how the speed of a moving unexpected object influences inattentional blindness. We demonstrated that inattentional blindness rates are considerably lower if the unexpected object moves more slowly, suggesting that it is the mere exposure time of the object rather than a higher saliency potentially induced by higher speed that determines the likelihood of its detection. Alternative explanations could be ruled out: The effect is not based on a pop-out effect arising from different motion speeds in relation to the primary-task stimuli (Experiment 2), nor is it based on a higher saliency of slow-moving unexpected objects (Experiment 3).

  1. Speed

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Speed. The rate of information transferred per second is the speed of the information. Measured in bits per second. Need for speed on the net: You-Tube phenomenon; IPTV; 3D Video telephony. Online gaming; HDTV.

  2. Effect of Hydraulic Retention Time on Anaerobic Digestion of Wheat Straw in the Semicontinuous Continuous Stirred-Tank Reactors

    Directory of Open Access Journals (Sweden)

    Xiao-Shuang Shi

    2017-01-01

    Full Text Available Three semicontinuous continuous stirred-tank reactors (CSTR operating at mesophilic conditions (35°C were used to investigate the effect of hydraulic retention time (HRT on anaerobic digestion of wheat straw. The results showed that the average biogas production with HRT of 20, 40, and 60 days was 46.8, 79.9, and 89.1 mL/g total solid as well as 55.2, 94.3, and 105.2 mL/g volatile solids, respectively. The methane content with HRT of 20 days, from 14.2% to 28.5%, was the lowest among the three reactors. The pH values with HRT of 40 and 60 days were in the acceptable range compared to that with HRT of 20 days. The propionate was dominant in the reactor with HRT of 20 days, inhibiting the activities of methanogens and causing the lower methane content in biogas. The degradation of cellulose, hemicellulose, and crystalline cellulose based on XRD was also strongly influenced by HRTs.

  3. Exploring the time-saving bias: How drivers misestimate time saved when increasing speed

    Directory of Open Access Journals (Sweden)

    Eyal Peer

    2010-12-01

    Full Text Available According to the time-saving bias, drivers underestimate the time saved when increasing from a low speed and overestimate the time saved when increasing from a relatively high speed. Previous research used a specific type of task --- drivers were asked to estimate time saved when increasing speed and to give a numeric response --- to show this. The present research conducted two studies with multiple questions to show that the time-saving bias occurs in other tasks. Study 1 found that drivers committed the time-saving bias when asked to estimate (a the time saved when increasing speed or (b the distance that can be completed at a given time when increasing speed or (c the speed required to complete a given distance in decreasing times. Study 2 showed no major differences in estimations of time saved compared to estimations of the remaining journey time and also between responses given on a numeric scale versus a visual analog scale. Study 3 tested two possible explanations for the time-saving bias: a Proportion heuristic and a Differences heuristic. Some evidence was found for use of the latter.

  4. Reticles, write time, and the need for speed

    Science.gov (United States)

    Ackmann, Paul W.; Litt, Lloyd C.; Ning, Guo Xiang

    2014-10-01

    Historical data indicates reticle write times are increasing node-to-node. The cost of mask sets is increasing driven by the tighter requirements and more levels. The regular introduction of new generations of mask patterning tools with improved performance is unable to fully compensate for the increased data and complexity required. Write time is a primary metric that drives mask fabrication speed. Design (Raw data) is only the first step in the process and many interactions between mask and wafer technology such as OPC used, OPC efficiency for writers, fracture engines, and actual field size used drive total write time. Yield, technology, and inspection rules drive the remaining raw cycle time. Yield can be even more critical for speed of delivery as it drives re-writes and wasted time. While intrinsic process yield is important, repair capability is the reason mask delivery is still able to deliver 100% good reticles to the fab. Advanced nodes utilizing several layers of multiple patterning may require mask writer tool dedication to meet image placement specifications. This will increase the effective mask cycle time for a layer mask set and drive the need for additional mask write capability in order to deliver masks at the rate required by the wafer fab production schedules.

  5. Residence Time Distribution of Solid Particles in High-Aspect Ratio Multiple-Impeller Stirred Vessel

    Czech Academy of Sciences Publication Activity Database

    Scargiali, F.; Grisafi, F.; Čermáková, Jiřina; Machoň, V.; Brucato, A.

    2004-01-01

    Roč. 59, č. 17 (2004), s. 3601-3618 ISSN 0009-2509 Institutional research plan: CEZ:AV0Z4072921 Keywords : retention time distribution * twin systems approach * particle tracing Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.655, year: 2004

  6. Friction stir welding of 6061 aluminium alloy

    International Nuclear Information System (INIS)

    Abdel Rahman, M.A.M.S.

    2009-01-01

    6061 AA (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to-weight ratio and good corrosion resistance such as marine frames, pipelines, storage tanks, and aircraft components [1]. It is also used for the manufacturing of fuel elements in the nuclear research reactors. Compared to many of the fusion welding processes that are routinely used for joining structural alloys, friction stir welding (FSW) is a solid state joining process in which the material that is being welded is not melted and recast [2]. The welding parameters such as tool rotational speed, welding traverse speed, and tool profile play a major role in deciding the weld quality. Several FSW tools (differ from each other in pin angle, shoulder diameter, and shoulder concavity) have been used to fabricate a number of joints in order to obtain a tool with which a sound weld can be produced. It was found that the FSW tool with tapered cone pin, concave shoulder, and shoulder diameter equal to four times the welded plate thickness is suitable to produce a sound weld. The effect of the traverse speed on the global and local tensile properties of friction stir welded joints has been investigated in the 6061-T6 AA. The global tensile properties of the FSW joints were improved with increasing the traverse speed at constant rotation rate. It is found that the global tensile strength of the FSW joint is limited by the local tensile strength of the nearest region to the weld center at which the cross section is composed mainly of the HAZ. The effect of the initial butt surface on the formation of the zigzag line on the tensile properties of the welds was examined by using three types of welding samples differ in the preparation of the initial butt surface. The first type of samples welded without removing the oxide layer from the initial butt surface (uncleaned butt surfaces joint). In the second type of samples the oxide layer was removed from

  7. Quantum speed limit time in a magnetic resonance

    Science.gov (United States)

    Ivanchenko, E. A.

    2017-12-01

    A visualization for dynamics of a qudit spin vector in a time-dependent magnetic field is realized by means of mapping a solution for a spin vector on the three-dimensional spherical curve (vector hodograph). The obtained results obviously display the quantum interference of precessional and nutational effects on the spin vector in the magnetic resonance. For any spin the bottom bounds of the quantum speed limit time (QSL) are found. It is shown that the bottom bound goes down when using multilevel spin systems. Under certain conditions the non-nil minimal time, which is necessary to achieve the orthogonal state from the initial one, is attained at spin S = 2. An estimation of the product of two and three standard deviations of the spin components are presented. We discuss the dynamics of the mutual uncertainty, conditional uncertainty and conditional variance in terms of spin standard deviations. The study can find practical applications in the magnetic resonance, 3D visualization of computational data and in designing of optimized information processing devices for quantum computation and communication.

  8. Molecularly imprinted polymeric stir bar: Preparation and application for the determination of naftopidil in plasma and urine samples.

    Science.gov (United States)

    Peng, Jun; Xiao, Deli; He, Hua; Zhao, Hongyan; Wang, Cuixia; Shi, Tian; Shi, Kexin

    2016-01-01

    In this study, molecularly imprinting technology and stir bar absorption technology were combined to develop a microextraction approach based on a molecularly imprinted polymeric stir bar. The molecularly imprinted polymer stir bar has a high performance, is specific, economical, and simple to prepare. The obtained naftopidil-imprinted polymer-coated bars could simultaneously agitate and adsorb naftopidil in the sample solution. The ratio of template/monomer/cross-linker and conditions of template removal were optimized to prepare a stir bar with highly efficient adsorption. Fourier transform infrared spectroscopy, scanning electron microscopy, selectivity, and extraction capacity experiments showed that the molecularly imprinted polymer stir bar was prepared successfully. To utilize the molecularly imprinted polymer stir bar for the determination of naftopidil in complex body fluid matrices, the extraction time, stirring speed, eluent, and elution time were optimized. The limits of detection of naftopidil in plasma and urine sample were 7.5 and 4.0 ng/mL, respectively, and the recoveries were in the range of 90-112%. The within-run precision and between-run precision were acceptable (relative standard deviation bar based microextraction with high-performance liquid chromatography was a convenient, rapid, efficient, and specific method for the precise determination of trace naftopidil in clinical analysis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Experimental study of laminar and turbulent flame speed of a spherical flame in a fan-stirred closed vessel for hydrogen safety application

    Energy Technology Data Exchange (ETDEWEB)

    Goulier, J. [Institut de Combustion, Aérothermique, Réactivité et Environnement, CNRS-ICARE (France); Institut de Radioprotection et de Sûreté Nucléaire (IRSN) (France); Chaumeix, N., E-mail: chaumeix@cnrs-orleans.fr [Institut de Combustion, Aérothermique, Réactivité et Environnement, CNRS-ICARE (France); Halter, F. [Institut de Combustion, Aérothermique, Réactivité et Environnement, CNRS-ICARE (France); Meynet, N.; Bentaïb, A. [Institut de Radioprotection et de Sûreté Nucléaire (IRSN) (France)

    2017-02-15

    The aim of this paper is to report new experimental results on the effect of turbulence on the propagation speed of hydrogen/air flames. To do so, a new experimental setup, called the spherical bomb, has been designed and built at CNRS-ICARE laboratory. With this new setup, the effect of a given and well-characterized turbulence intensity on the increase of hydrogen/air flame speed can be investigated. This new facility consists of a spherical vessel equipped (563 mm internal diameter) equipped with 8 motors which are linked to fans inside the bomb. Fan actuation induces the generation of a turbulent flow inside the vessel prior to any ignition. The spherical bomb is equipped with 4 quartz windows (200 mm optical diameter) that allow the use of a Particle Image Velocimetry diagnostic in order to characterize the turbulence level inside the bomb. The flame propagation was recorded using a high speed camera at 19,002 frames per second. These experiments were performed for lean to stoichiometric hydrogen/air mixtures (16–20% of H{sub 2} in air), initially at ambient temperature and pressure, and for a rotation speed from 1000 to 5000 rpm. The PIV measurements showed that a homogeneous and isotropic turbulence is created with a fluctuation speed that can reach 4 m/s at 5000 rpm.

  10. Friction stir spot welding of dissimilar aluminium alloys

    International Nuclear Information System (INIS)

    Bozkurt, Yahya

    2016-01-01

    Friction stir spot welding (FSSW) has been proposed as an effective technology to spot weld the so-called “difficult to be welded” metal alloys such as thin sheets aluminum alloys and dissimilar materials. FSSW is derived from friction stir welding technology, its principle benefit being low cost joining, lower welding temperature and shorter welding time than conventional welding methods. In this study, dissimilar AlMg 3 and AlCu 4 Mg 1 aluminium alloy plates were FSSWed by offsetting the low strength sheet on upper side of the weld. The effects of tool rotation speed on the microstructure, lap shear fracture load (LSFL), microhardness and fracture features of the weld are investigated by constant welding parameters. The maximum LSFL was obtained by increasing the tool rotational speed. However, the joints exhibited pull-out nugget fracture mode under lap shear tensile testing conditions. The largest completely bonded zone was observed as 5.86 mm which was narrower at the opposite position of the joint. Key words: friction stir spot welding, aluminium alloys, mechanical properties, dissimilar joint, welding parameters

  11. Model of a synthetic wind speed time series generator

    DEFF Research Database (Denmark)

    Negra, N.B.; Holmstrøm, O.; Bak-Jensen, B.

    2008-01-01

    is described and some statistical issues (seasonal characteristics, autocorrelation functions, average values and distribution functions) are used for verification. The output of the model has been designed as input for sequential Monte Carlo simulation; however, it is expected that it can be used for other...... of the main elements to consider for this purpose is the model of the wind speed that is usually required as input. Wind speed measurements may represent a solution for this problem, but, for techniques such as sequential Monte Carlo simulation, they have to be long enough in order to describe a wide range...

  12. Time-interleaved high-speed D/A converters

    NARCIS (Netherlands)

    Olieman, E.

    2016-01-01

    This thesis is on power efficient very high-speed digital-to-analog converters (DACs) in CMOS technology, intended to generate signals from DC to RF. Components in RF signal chains are nowadays often moved from the analog domain to the digital domain. This allows for more flexibility and better

  13. Ultrasonic Stir Welding

    Science.gov (United States)

    Nabors, Sammy

    2015-01-01

    NASA Marshall Space Flight Center (MSFC) developed Ultrasonic Stir Welding (USW) to join large pieces of very high-strength metals such as titanium and Inconel. USW, a solid-state weld process, improves current thermal stir welding processes by adding high-power ultrasonic (HPU) energy at 20 kHz frequency. The addition of ultrasonic energy significantly reduces axial, frictional, and shear forces; increases travel rates; and reduces wear on the stir rod, which results in extended stir rod life. The USW process decouples the heating, stirring, and forging elements found in the friction stir welding process allowing for independent control of each process element and, ultimately, greater process control and repeatability. Because of the independent control of USW process elements, closed-loop temperature control can be integrated into the system so that a constant weld nugget temperature can be maintained during welding.

  14. Fine tuning of dwelling time in friction stir welding for preventing material overheating, weld tensile strength increase and weld nugget size decrease

    Directory of Open Access Journals (Sweden)

    Mijajlović Miroslav M.

    2016-01-01

    Full Text Available After successful welding, destructive testing into test samples from Al 2024-T351 friction stir butt welds showed that tensile strength of the weld improve along the joint line, while dimensions of the weld nugget decrease. For those welds, both the base material and the welding tool constantly cool down during the welding phase. Obviously, the base material became overheated during the long dwelling phase what made conditions for creation of joints with the reduced mechanical properties. Preserving all process parameters but varying the dwelling time from 5-27 seconds a new set of welding is done to reach maximal achievable tensile strength. An analytical-numerical-experimental model is used for optimising the duration of the dwelling time while searching for the maximal tensile strength of the welds

  15. Microstructure characterization of the stir zone of submerged friction stir processed aluminum alloy 2219

    International Nuclear Information System (INIS)

    Feng, Xiuli; Liu, Huijie; Lippold, John C.

    2013-01-01

    Aluminum alloy 2219-T6 was friction stir processed using a novel submerged processing technique to facilitate cooling. Processing was conducted at a constant tool traverse speed of 200 mm/min and spindle rotation speeds in the range from 600 to 800 rpm. The microstructural characteristics of the base metal and processed zone, including grain structure and precipitation behavior, were studied using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Microhardness maps were constructed on polished cross sections of as-processed samples. The effect of tool rotation speed on the microstructure and hardness of the stir zone was investigated. The average grain size of the stir zone was much smaller than that of the base metal, but the hardness was also lower due to the formation of equilibrium θ precipitates from the base metal θ′ precipitates. Stir zone hardness was found to decrease with increasing rotation speed (heat input). The effect of processing conditions on strength (hardness) was rationalized based on the competition between grain refinement strengthening and softening due to precipitate overaging. - Highlights: • SZ grain size (∼ 1 μm) is reduced by over one order of magnitude relative to the BM. • Hardness in the SZ is lower than that of the precipitation strengthened BM. • Metastable θ′ in the base metal transforms to equilibrium θ in the stir zone. • Softening in the SZ results from a decrease of precipitation strengthening

  16. Microstructure characterization of the stir zone of submerged friction stir processed aluminum alloy 2219

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xiuli, E-mail: feng.97@osu.edu [Welding Engineering Program, Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43221 (United States); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Liu, Huijie, E-mail: liuhj@hit.edu.cn [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Lippold, John C., E-mail: lippold.1@osu.edu [Welding Engineering Program, Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43221 (United States)

    2013-08-15

    Aluminum alloy 2219-T6 was friction stir processed using a novel submerged processing technique to facilitate cooling. Processing was conducted at a constant tool traverse speed of 200 mm/min and spindle rotation speeds in the range from 600 to 800 rpm. The microstructural characteristics of the base metal and processed zone, including grain structure and precipitation behavior, were studied using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Microhardness maps were constructed on polished cross sections of as-processed samples. The effect of tool rotation speed on the microstructure and hardness of the stir zone was investigated. The average grain size of the stir zone was much smaller than that of the base metal, but the hardness was also lower due to the formation of equilibrium θ precipitates from the base metal θ′ precipitates. Stir zone hardness was found to decrease with increasing rotation speed (heat input). The effect of processing conditions on strength (hardness) was rationalized based on the competition between grain refinement strengthening and softening due to precipitate overaging. - Highlights: • SZ grain size (∼ 1 μm) is reduced by over one order of magnitude relative to the BM. • Hardness in the SZ is lower than that of the precipitation strengthened BM. • Metastable θ′ in the base metal transforms to equilibrium θ in the stir zone. • Softening in the SZ results from a decrease of precipitation strengthening.

  17. Stirring Strongly Coupled Plasma

    CERN Document Server

    Fadafan, Kazem Bitaghsir; Rajagopal, Krishna; Wiedemann, Urs Achim

    2009-01-01

    We determine the energy it takes to move a test quark along a circle of radius L with angular frequency w through the strongly coupled plasma of N=4 supersymmetric Yang-Mills (SYM) theory. We find that for most values of L and w the energy deposited by stirring the plasma in this way is governed either by the drag force acting on a test quark moving through the plasma in a straight line with speed v=Lw or by the energy radiated by a quark in circular motion in the absence of any plasma, whichever is larger. There is a continuous crossover from the drag-dominated regime to the radiation-dominated regime. In the crossover regime we find evidence for significant destructive interference between energy loss due to drag and that due to radiation as if in vacuum. The rotating quark thus serves as a model system in which the relative strength of, and interplay between, two different mechanisms of parton energy loss is accessible via a controlled classical gravity calculation. We close by speculating on the implicati...

  18. Comparison of Taxi Time Prediction Performance Using Different Taxi Speed Decision Trees

    Science.gov (United States)

    Lee, Hanbong

    2017-01-01

    In the STBO modeler and tactical surface scheduler for ATD-2 project, taxi speed decision trees are used to calculate the unimpeded taxi times of flights taxiing on the airport surface. The initial taxi speed values in these decision trees did not show good prediction accuracy of taxi times. Using the more recent, reliable surveillance data, new taxi speed values in ramp area and movement area were computed. Before integrating these values into the STBO system, we performed test runs using live data from Charlotte airport, with different taxi speed settings: 1) initial taxi speed values and 2) new ones. Taxi time prediction performance was evaluated by comparing various metrics. The results show that the new taxi speed decision trees can calculate the unimpeded taxi-out times more accurately.

  19. Dry grinding of talc in a stirred ball mill

    Directory of Open Access Journals (Sweden)

    Cayirli Serkan

    2016-01-01

    Full Text Available The aim of this work was to investigate micro fine size dry grindability of talc in a stirred ball mill. The effects of various parameters such as grinding time, stirrer speed, powder filling ratio and ball filling ratio were investigated. Alumina balls were used as grinding media. Experiments were carried out using the 24 full factorial design. The main and interaction effects were evaluated using the Yates method. Test results were evaluated on the basis of product size and surface area.

  20. Stirring by swimming bodies

    International Nuclear Information System (INIS)

    Thiffeault, Jean-Luc; Childress, Stephen

    2010-01-01

    We consider the stirring of an inviscid fluid caused by the locomotion of bodies through it. The swimmers are approximated by non-interacting cylinders or spheres moving steadily along straight lines. We find the displacement of fluid particles caused by the nearby passage of a swimmer as a function of an impact parameter. We use this to compute the effective diffusion coefficient from the random walk of a fluid particle under the influence of a distribution of swimming bodies. We compare with the results of simulations. For typical sizes, densities and swimming velocities of schools of krill, the effective diffusivity in this model is five times the thermal diffusivity. However, we estimate that viscosity increases this value by two orders of magnitude.

  1. The Effect of Rotation Stirring on Macrosegregation in Bi-Sn Alloy

    Directory of Open Access Journals (Sweden)

    Zulaida Yeni Muriani

    2017-01-01

    Full Text Available Macrosegregation is a defect that difficult to avoid in a metal alloy made by casting method. Macrosegregation can cause decreasing in mechanical properties of casting products. It will reduce their performance in industrial application. Macrosegregation is convinced occur during solidification time in liquid alloy. In the early solidified, The solids move upward/downward in liquid alloy during solidification are considered to contribute on macrosegregation formation. This movement occur due to the density differences between the solid and the surrounding liquid. This research want to observe the effect of stirring on macrosegregation formation for interfering on the movement of initial solidified solid. Stiring with rotation method is applied in this experiment at certain temperature. The temperature and the rotation speed of stirring are varied to observe the effect of rotation stirring on macrosegregation formation. The mold is covered by insulation jacket and kept the bottom part opened in order to obtain the directionally solidification. The result shows that the rotation stirring can change the macrostructure of casting but in case of composition distribution, the macrosegregation still appear. Increasing the rotation stirring will rise solid crystals up and the macrosegregation become more uniform and the treatment is better if conducting at lower temperature.

  2. MSVAT-SPACE-STIR and SEMAC-STIR for Reduction of Metallic Artifacts in 3T Head and Neck MRI.

    Science.gov (United States)

    Hilgenfeld, T; Prager, M; Schwindling, F S; Nittka, M; Rammelsberg, P; Bendszus, M; Heiland, S; Juerchott, A

    2018-05-24

    The incidence of metallic dental restorations and implants is increasing, and head and neck MR imaging is becoming challenging regarding artifacts. Our aim was to evaluate whether multiple-slab acquisition with view angle tilting gradient based on a sampling perfection with application-optimized contrasts by using different flip angle evolution (MSVAT-SPACE)-STIR and slice-encoding for metal artifact correction (SEMAC)-STIR are beneficial regarding artifact suppression compared with the SPACE-STIR and TSE-STIR in vitro and in vivo. At 3T, 3D artifacts of 2 dental implants, supporting different single crowns, were evaluated. Image quality was evaluated quantitatively (normalized signal-to-noise ratio) and qualitatively (2 reads by 2 blinded radiologists). Feasibility was tested in vivo in 5 volunteers and 5 patients, respectively. Maximum achievable resolution and the normalized signal-to-noise ratio of MSVAT-SPACE-STIR were higher compared with SEMAC-STIR. Performance in terms of artifact correction was dependent on the material composition. For highly paramagnetic materials, SEMAC-STIR was superior to MSVAT-SPACE-STIR (27.8% smaller artifact volume) and TSE-STIR (93.2% less slice distortion). However, MSVAT-SPACE-STIR reduced the artifact size compared with SPACE-STIR by 71.5%. For low-paramagnetic materials, MSVAT-SPACE-STIR performed as well as SEMAC-STIR. Furthermore, MSVAT-SPACE-STIR decreased artifact volume by 69.5% compared with SPACE-STIR. The image quality of all sequences did not differ systematically. In vivo results were comparable with in vitro results. Regarding susceptibility artifacts and acquisition time, MSVAT-SPACE-STIR might be advantageous over SPACE-STIR for high-resolution and isotropic head and neck imaging. Only for materials with high-susceptibility differences to soft tissue, the use of SEMAC-STIR might be beneficial. Within limited acquisition times, SEMAC-STIR cannot exploit its full advantage over TSE-STIR regarding artifact

  3. Influence of the laser light absorption by the colloid on the properties of silver nanoparticles produced by laser ablation in stirred and stationary liquid

    International Nuclear Information System (INIS)

    Resano-Garcia, A.; Battie, Y.; Koch, A.; En Naciri, A.; Chaoui, N.

    2015-01-01

    Silver nanoparticles were produced by nanosecond pulsed-laser ablation at 1064 nm of Ag in pure water. These experiments were performed using an alternative ablation cell design where a cylindrical shaped Ag target was horizontally irradiated, while the liquid was stirred by a stir rod coaxially arranged to the target. The repeatability of the generated colloids properties (extinction and size distribution) is assessed by statistical tools. The colloids properties prepared under stationary liquid are found to be unpredictable, while they are highly repeatable at high stirring speed. At the same time, electronic microscopy examinations of the irradiated Ag targets revealed that the width of the laser-machined grooves exponentially decays in stationary liquid and almost linearly under high stirring speed as the ablation proceeds. In the latter case, the decay rate was found to be constant from one experiment to the other, while it was not repeatable stationary liquid. We show that the decay of the groove width is due to an attenuation of the laser energy reaching the target surface due to the formation of a more or less dense NPs layer in front of the target as the ablation proceeds. Using the ablation time-dependence of the groove width, we can quantify the attenuation factor of the laser energy with exposure time. Finally, the relationship between the laser energy attenuation, stirring speed, and repeatability of the colloids properties is interpreted and discussed in terms of mass transfer

  4. Bluetooth-based travel time/speed measuring systems development.

    Science.gov (United States)

    2010-06-01

    Agencies in the Houston region have traditionally used toll tag readers to provide travel times on : freeways and High Occupancy Vehicle (HOV) lanes, but these systems require large amounts of costly and : physically invasive infrastructure. Bluetoot...

  5. Pacing Strategy, Muscle Fatigue and Technique in 1500m Speed Skating and Cycling Time-Trials

    NARCIS (Netherlands)

    Stoter, Inge K; MacIntosh, Brian R; Fletcher, Jared R; Pootz, Spencer; Zijdewind, Inge; Hettinga, Florentina J

    2016-01-01

    PURPOSE: To evaluate pacing behavior and peripheral and central contributions to muscle fatigue in 1500m speed skating and cycling time-trials, when a faster or slower start is instructed. METHODS: Nine speed skaters and nine cyclists, all competing at regional or national level, performed two 1500m

  6. The Triggers, Timing and Speed of New Product Price Landings

    NARCIS (Netherlands)

    C. Hernández-Mireles (Carlos); D. Fok (Dennis); Ph.H.B.F. Franses (Philip Hans)

    2008-01-01

    textabstractMany high-tech products and durable goods exhibit exactly one significant price cut some time after their launch. We call this sudden transition from high to low prices the price landing. In this paper we present a new model that describes two important features of price landings: their

  7. Running speed during training and percent body fat predict race time in recreational male marathoners.

    Science.gov (United States)

    Barandun, Ursula; Knechtle, Beat; Knechtle, Patrizia; Klipstein, Andreas; Rüst, Christoph Alexander; Rosemann, Thomas; Lepers, Romuald

    2012-01-01

    Recent studies have shown that personal best marathon time is a strong predictor of race time in male ultramarathoners. We aimed to determine variables predictive of marathon race time in recreational male marathoners by using the same characteristics of anthropometry and training as used for ultramarathoners. Anthropometric and training characteristics of 126 recreational male marathoners were bivariately and multivariately related to marathon race times. After multivariate regression, running speed of the training units (β = -0.52, P marathon race times. Marathon race time for recreational male runners may be estimated to some extent by using the following equation (r (2) = 0.44): race time ( minutes) = 326.3 + 2.394 × (percent body fat, %) - 12.06 × (speed in training, km/hours). Running speed during training sessions correlated with prerace percent body fat (r = 0.33, P = 0.0002). The model including anthropometric and training variables explained 44% of the variance of marathon race times, whereas running speed during training sessions alone explained 40%. Thus, training speed was more predictive of marathon performance times than anthropometric characteristics. The present results suggest that low body fat and running speed during training close to race pace (about 11 km/hour) are two key factors for a fast marathon race time in recreational male marathoner runners.

  8. Friction stir welding tool

    Science.gov (United States)

    Tolle,; Charles R. , Clark; Denis E. , Barnes; Timothy, A [Ammon, ID

    2008-04-15

    A friction stir welding tool is described and which includes a shank portion; a shoulder portion which is releasably engageable with the shank portion; and a pin which is releasably engageable with the shoulder portion.

  9. First and second order Markov chain models for synthetic generation of wind speed time series

    International Nuclear Information System (INIS)

    Shamshad, A.; Bawadi, M.A.; Wan Hussin, W.M.A.; Majid, T.A.; Sanusi, S.A.M.

    2005-01-01

    Hourly wind speed time series data of two meteorological stations in Malaysia have been used for stochastic generation of wind speed data using the transition matrix approach of the Markov chain process. The transition probability matrices have been formed using two different approaches: the first approach involves the use of the first order transition probability matrix of a Markov chain, and the second involves the use of a second order transition probability matrix that uses the current and preceding values to describe the next wind speed value. The algorithm to generate the wind speed time series from the transition probability matrices is described. Uniform random number generators have been used for transition between successive time states and within state wind speed values. The ability of each approach to retain the statistical properties of the generated speed is compared with the observed ones. The main statistical properties used for this purpose are mean, standard deviation, median, percentiles, Weibull distribution parameters, autocorrelations and spectral density of wind speed values. The comparison of the observed wind speed and the synthetically generated ones shows that the statistical characteristics are satisfactorily preserved

  10. Mechanical properties of friction stir welded 11Cr-ferritic/martensitic steel

    International Nuclear Information System (INIS)

    Yano, Y.; Sato, Y.S.; Sekio, Y.; Ohtsuka, S.; Kaito, T.; Ogawa, R.; Kokawa, H.

    2013-01-01

    Friction stir welding was applied to the wrapper tube materials, 11Cr-ferritic/martensitic steel, designed for fast reactors and defect-free welds were successfully produced. The mechanical and microstructural properties of the friction stir welded steel were subsequently investigated. The hardness values of the stir zone were approximately 550 Hv (5.4 GPa) with minimal dependence on the rotational speed, even though they were much higher than those of the base material. However, tensile strengths and elongations of the stir zones were high at 298 K, compared to those of the base material. The excellent tensile properties are attributable to the fine grain formation during friction stir welding

  11. Real Time Speed Measure while Automobile Braking on Soft Sensing Technique

    International Nuclear Information System (INIS)

    Zhu, W B; Li, D S; Lu, Y

    2006-01-01

    Because the braking performance of automobile has close relationship to traffic safety, it is important to detect that. Focusing on the problem that the real time speed is difficult to obtain in detection process, soft sensing technique is introduced in this paper. According to analyzing the relationship of the dynamics equation of a moving automobile, a module of real time speed of braking is set up. By using imitation method with experiment data to get the pressure function of cylinder and analyzing the relationship between the trigging moment of a wheel and the pressure function of brake cylinder, the real time speed is confirmed in good precision. The maximal measurement error of real time speed is 8.7% and the precision can satisfy engineering request

  12. SPEED: A Stateless Protocol for Real-Time Communication in Sensor Networks

    National Research Council Canada - National Science Library

    He, Tian; Stankovic, John A; Lu, Chenyang; Abdelzaher, Tarek

    2003-01-01

    .... End-to-end soft real-time communication is achieved by maintaining a desired delivery speed across the sensor network through a novel combination of feedback control and non-deterministic geographic forwarding...

  13. Real Time Speed Measure while Automobile Braking on Soft Sensing Technique

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, W B; Li, D S; Lu, Y [China Jiliang University, Hangzhou, Zhejiang province, 310018 (China)

    2006-10-15

    Because the braking performance of automobile has close relationship to traffic safety, it is important to detect that. Focusing on the problem that the real time speed is difficult to obtain in detection process, soft sensing technique is introduced in this paper. According to analyzing the relationship of the dynamics equation of a moving automobile, a module of real time speed of braking is set up. By using imitation method with experiment data to get the pressure function of cylinder and analyzing the relationship between the trigging moment of a wheel and the pressure function of brake cylinder, the real time speed is confirmed in good precision. The maximal measurement error of real time speed is 8.7% and the precision can satisfy engineering request.

  14. Reaction time, processing speed and sustained attention in schizophrenia: impact on social functioning.

    Science.gov (United States)

    Lahera, Guillermo; Ruiz, Alicia; Brañas, Antía; Vicens, María; Orozco, Arantxa

    Previous studies have linked processing speed with social cognition and functioning of patients with schizophrenia. A discriminant analysis is needed to determine the different components of this neuropsychological construct. This paper analyzes the impact of processing speed, reaction time and sustained attention on social functioning. 98 outpatients between 18 and 65 with DSM-5 diagnosis of schizophrenia, with a period of 3 months of clinical stability, were recruited. Sociodemographic and clinical data were collected, and the following variables were measured: processing speed (Trail Making Test [TMT], symbol coding [BACS], verbal fluency), simple and elective reaction time, sustained attention, recognition of facial emotions and global functioning. Processing speed (measured only through the BACS), sustained attention (CPT) and elective reaction time (but not simple) were associated with functioning. Recognizing facial emotions (FEIT) correlated significantly with scores on measures of processing speed (BACS, Animals, TMT), sustained attention (CPT) and reaction time. The linear regression model showed a significant relationship between functioning, emotion recognition (P=.015) and processing speed (P=.029). A deficit in processing speed and facial emotion recognition are associated with worse global functioning in patients with schizophrenia. Copyright © 2017 SEP y SEPB. Publicado por Elsevier España, S.L.U. All rights reserved.

  15. Recovery of resources for advanced life support space applications: effect of retention time on biodegradation of two crop residues in a fed-batch, continuous stirred tank reactor

    Science.gov (United States)

    Strayer, R. F.; Finger, B. W.; Alazraki, M. P.; Cook, K.; Garland, J. L.

    2002-01-01

    Bioreactor retention time is a key process variable that will influence costs that are relevant to long distance space travel or long duration space habitation. However. little is known about the effects of this parameter on the microbiological treatment options that are being proposed for Advanced Life Support (ALS) systems. Two bioreactor studies were designed to examine this variable. In the first one, six retention times ranging from 1.3 to 21.3 days--were run in duplicate, 81 working-volume continuous stirred tank reactors (CSTR) that were fed ALS wheat residues. Ash-free dry weight loss, carbon mineralization, soluble TOC reduction, changes in fiber content (cellulose, hemicellulose, and lignin), bacterial numbers, and mineral recoveries were monitored. At short retention times--1.33 days--biodegradation was poor (total: 16-20%, cellulose - 12%, hemicellulose - 28%) but soluble TOC was decreased by 75-80% and recovery of major crop inorganic nutrients was adequate, except for phosphorus. A high proportion of the total bacteria (ca. 83%) was actively respiring. At the longest retention time tested, 21.3 days, biodegradation was good (total: 55-60%, cellulose ca. 70%, hemicellulose - ca. 55%) and soluble TOC was decreased by 80%. Recovery of major nutrients, except phosphorus, remained adequate. A very low proportion of total bacteria was actively respiring (ca. 16%). The second bioreactor study used potato residue to determine if even shorter retention times could be used (range 0.25-2.0 days). Although overall biodegradation deteriorated, the degradation of soluble TOC continued to be ca. 75%. We conclude that if the goal of ALS bioprocessing is maximal degradation of crop residues, including cellulose, then retention times of 10 days or longer will be needed. If the goal is to provide inorganic nutrients with the smallest volume/weight bioreactor possible, then a retention time of 1 day (or less) is sufficient.

  16. The Time Lens Concept Applied to Ultra-High-Speed OTDM Signal Processing

    DEFF Research Database (Denmark)

    Clausen, Anders; Palushani, Evarist; Mulvad, Hans Christian Hansen

    2013-01-01

    This survey paper presents some of the applications where the versatile time-lens concept successfully can be applied to ultra-high-speed serial systems by offering expected needed functionalities for future optical communication networks.......This survey paper presents some of the applications where the versatile time-lens concept successfully can be applied to ultra-high-speed serial systems by offering expected needed functionalities for future optical communication networks....

  17. Effects of Temperature and Stirring on Mass Transfer to Maximize Biodiesel Production from Jatropha curcas Oil: A Mathematical Study

    Directory of Open Access Journals (Sweden)

    Fahad Al Basir

    2015-01-01

    Full Text Available Biodiesel, the most promising renewable and alternative energy, is produced through transesterification of vegetable oils. One of the most cost effective sources of biodiesel is Jatropha curcas oil. Transesterification of Jatropha oil depends significantly on reaction parameters such as reaction time, temperature, molar ratio, catalyst amount, and stirrer speed. Among these parameters temperature and stirring have noteworthy effect on mass transfer. In this research article, we have shown the simultaneous effect of temperature and stirring on mass transfer by considering a mathematical model. The optimal profiles of temperature and stirring are determined as a combined parameter, for which maximum biodiesel can be obtained. Further, we have shown that this pair exists and is unique for the optimality of the system.

  18. Applications of Friction Stir Processing during Engraving of Soft Materials

    Directory of Open Access Journals (Sweden)

    V. Kočović

    2015-12-01

    Full Text Available Friction stir processing has extensive application in many technological operations. Application area of friction stir processing can be extended to the processing of non-metallic materials, such as wood. The paper examines the friction stir processing contact between a specially designed hard and temperature-resistant rotating tool and workpiece which is made of wood. Interval of speed slip and temperature level under which the combustion occurs and carbonization layer of soft material was determined. The results of the research can be applied in technological process of wood engraving operations which may have significant technological and aesthetic effects.

  19. Driver's behavioral adaptation to adaptive cruise control (ACC): the case of speed and time headway.

    Science.gov (United States)

    Bianchi Piccinini, Giulio Francesco; Rodrigues, Carlos Manuel; Leitão, Miguel; Simões, Anabela

    2014-06-01

    The Adaptive Cruise Control is an Advanced Driver Assistance System (ADAS) that allows maintaining given headway and speed, according to settings pre-defined by the users. Despite the potential benefits associated to the utilization of ACC, previous studies warned against negative behavioral adaptations that might occur while driving with the system activated. Unfortunately, up to now, there are no unanimous results about the effects induced by the usage of ACC on speed and time headway to the vehicle in front. Also, few studies were performed including actual users of ACC among the subjects. This research aimed to investigate the effect of the experience gained with ACC on speed and time headway for a group of users of the system. In addition, it explored the impact of ACC usage on speed and time headway for ACC users and regular drivers. A matched sample driving simulator study was planned as a two-way (2×2) repeated measures mixed design, with the experience with ACC as between-subjects factor and the driving condition (with ACC and manually) as within-subjects factor. The results show that the usage of ACC brought a small but not significant reduction of speed and, especially, the maintenance of safer time headways, being the latter result greater for ACC users, probably as a consequence of their experience in using the system. The usage of ACC did not cause any negative behavioral adaptations to the system regarding speed and time headway. Based on this research work, the Adaptive Cruise Control showed the potential to improve road safety for what concerns the speed and the time headway maintained by the drivers. The speed of the surrounding traffic and the minimum time headway settable through the ACC seem to have an important effect on the road safety improvement achievable with the system. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Molecularly imprinted polymers based stir bar sorptive extraction for determination of cefaclor and cefalexin in environmental water.

    Science.gov (United States)

    Peng, Jun; Liu, Donghao; Shi, Tian; Tian, Huairu; Hui, Xuanhong; He, Hua

    2017-07-01

    Although stir bar sportive extraction was thought to be a highly efficiency and simple pretreatment approach, its wide application was limited by low selectivity, short service life, and relatively high cost. In order to improve the performance of the stir bar, molecular imprinted polymers and magnetic carbon nanotubes were combined in the present study. In addition, two monomers were utilized to intensify the selectivity of molecularly imprinted polymers. Fourier transform infrared spectroscopy, scanning electron microscopy, and selectivity experiments showed that the molecularly imprinted polymeric stir bar was successfully prepared. Then micro-extraction based on the obtained stir bar was coupled with HPLC for determination of trace cefaclor and cefalexin in environmental water. This approach had the advantages of stir bar sportive extraction, high selectivity of molecular imprinted polymers, and high sorption efficiency of carbon nanotubes. To utilize this pretreatment approach, pH, extraction time, stirring speed, elution solvent, and elution time were optimized. The LOD and LOQ of cefaclor were found to be 3.5 ng · mL -1 and 12.0 ng · mL -1 , respectively; the LOD and LOQ of cefalexin were found to be 3.0 ng · mL -1 and 10.0 ng · mL -1 , respectively. The recoveries of cefaclor and cefalexin were 86.5 ~ 98.6%. The within-run precision and between-run precision were acceptable (relative standard deviation bar did not decrease dramatically. This demonstrated that the molecularly imprinted polymeric stir bar based micro-extraction was a convenient, efficient, low-cost, and a specific method for enrichment of cefaclor and cefalexin in environmental samples.

  1. Optimization of the Process Parameters for Controlling Residual Stress and Distortion in Friction Stir Welding

    DEFF Research Database (Denmark)

    Tutum, Cem Celal; Schmidt, Henrik Nikolaj Blicher; Hattel, Jesper Henri

    2008-01-01

    In the present paper, numerical optimization of the process parameters, i.e. tool rotation speed and traverse speed, aiming minimization of the two conflicting objectives, i.e. the residual stresses and welding time, subjected to process-specific thermal constraints in friction stir welding......, is investigated. The welding process is simulated in 2-dimensions with a sequentially coupled transient thermo-mechanical model using ANSYS. The numerical optimization problem is implemented in modeFRONTIER and solved using the Multi-Objective Genetic Algorithm (MOGA-II). An engineering-wise evaluation or ranking...

  2. Generation and Validation of Spatial Distribution of Hourly Wind Speed Time-Series using Machine Learning

    International Nuclear Information System (INIS)

    Veronesi, F; Grassi, S

    2016-01-01

    Wind resource assessment is a key aspect of wind farm planning since it allows to estimate the long term electricity production. Moreover, wind speed time-series at high resolution are helpful to estimate the temporal changes of the electricity generation and indispensable to design stand-alone systems, which are affected by the mismatch of supply and demand. In this work, we present a new generalized statistical methodology to generate the spatial distribution of wind speed time-series, using Switzerland as a case study. This research is based upon a machine learning model and demonstrates that statistical wind resource assessment can successfully be used for estimating wind speed time-series. In fact, this method is able to obtain reliable wind speed estimates and propagate all the sources of uncertainty (from the measurements to the mapping process) in an efficient way, i.e. minimizing computational time and load. This allows not only an accurate estimation, but the creation of precise confidence intervals to map the stochasticity of the wind resource for a particular site. The validation shows that machine learning can minimize the bias of the wind speed hourly estimates. Moreover, for each mapped location this method delivers not only the mean wind speed, but also its confidence interval, which are crucial data for planners. (paper)

  3. Generation and Validation of Spatial Distribution of Hourly Wind Speed Time-Series using Machine Learning

    Science.gov (United States)

    Veronesi, F.; Grassi, S.

    2016-09-01

    Wind resource assessment is a key aspect of wind farm planning since it allows to estimate the long term electricity production. Moreover, wind speed time-series at high resolution are helpful to estimate the temporal changes of the electricity generation and indispensable to design stand-alone systems, which are affected by the mismatch of supply and demand. In this work, we present a new generalized statistical methodology to generate the spatial distribution of wind speed time-series, using Switzerland as a case study. This research is based upon a machine learning model and demonstrates that statistical wind resource assessment can successfully be used for estimating wind speed time-series. In fact, this method is able to obtain reliable wind speed estimates and propagate all the sources of uncertainty (from the measurements to the mapping process) in an efficient way, i.e. minimizing computational time and load. This allows not only an accurate estimation, but the creation of precise confidence intervals to map the stochasticity of the wind resource for a particular site. The validation shows that machine learning can minimize the bias of the wind speed hourly estimates. Moreover, for each mapped location this method delivers not only the mean wind speed, but also its confidence interval, which are crucial data for planners.

  4. Real time data compactor (sparsifier) and 8 megabyte high speed FIFO for HEP

    International Nuclear Information System (INIS)

    Baumbaugh, A.E.; Knickerbocker, K.L.; Wegner, C.R.; Baumbaugh, B.W.; Ruchti, R.

    1985-10-01

    A Video-Data-Acquisition-System (VDAS) has been developed to record image data from a scintillating glass fiber-optic target developed for High Energy Physics. The major components of the VDAS are a flash ADC, a ''real time'' high speed data compactor, and high speed 8 megabyte FIFO memory. The data rates through the system are in excess of 30 megabytes/second. The compactor is capable of reducing the amount of data needed to reconstruct typical images by as much as a factor of 20. The FIFO uses only standard NMOS DRAMS and TTL components to achieve its large size and high speed at relatively low power and cost

  5. A Fully Polynomial-Time Approximation Scheme for Speed Scaling with Sleep State

    OpenAIRE

    Antoniadis, Antonios; Huang, Chien-Chung; Ott, Sebastian

    2014-01-01

    We study classical deadline-based preemptive scheduling of tasks in a computing environment equipped with both dynamic speed scaling and sleep state capabilities: Each task is specified by a release time, a deadline and a processing volume, and has to be scheduled on a single, speed-scalable processor that is supplied with a sleep state. In the sleep state, the processor consumes no energy, but a constant wake-up cost is required to transition back to the active state. In contrast to speed sc...

  6. Time Series Model of Wind Speed for Multi Wind Turbines based on Mixed Copula

    Directory of Open Access Journals (Sweden)

    Nie Dan

    2016-01-01

    Full Text Available Because wind power is intermittent, random and so on, large scale grid will directly affect the safe and stable operation of power grid. In order to make a quantitative study on the characteristics of the wind speed of wind turbine, the wind speed time series model of the multi wind turbine generator is constructed by using the mixed Copula-ARMA function in this paper, and a numerical example is also given. The research results show that the model can effectively predict the wind speed, ensure the efficient operation of the wind turbine, and provide theoretical basis for the stability of wind power grid connected operation.

  7. Measurements of Turbulent Convection Speeds in Multistream Jets Using Time-Resolved PIV

    Science.gov (United States)

    Bridges, James; Wernet, Mark P.

    2017-01-01

    Convection speeds of turbulent velocities in jets, including multi-stream jets with and without flight stream, were measured using an innovative application of time-resolved particle image velocimetry. The paper describes the unique instrumentation and data analysis that allows the measurement to be made. Extensive data is shown that relates convection speed, mean velocity, and turbulent velocities for multiple jet cases. These data support the overall observation that the local turbulent convection speed is roughly that of the local mean velocity, biased by the relative intensity of turbulence.

  8. Measurements of Turbulence Convection Speeds in Multistream Jets Using Time-Resolved PIV

    Science.gov (United States)

    Bridges, James; Wernet, Mark P.

    2017-01-01

    Convection speeds of turbulent velocities in jets, including multi-stream jets with and without flight stream, were measured using an innovative application of time-resolved particle image velocimetry. The paper describes the unique instrumentation and data analysis that allows the measurement to be made. Extensive data is shown that relates convection speed, mean velocity, and turbulent velocities for multiple jet cases. These data support the overall observation that the local turbulent convection speed is roughly that of the local mean velocity, biased by the relative intensity of turbulence.

  9. Effects of welding parameters on friction stir spot welding of high density polyethylene sheets

    International Nuclear Information System (INIS)

    Bilici, Mustafa Kemal; Yukler, Ahmet Irfan

    2012-01-01

    Graphical abstract: (a) Schematic illustration of the cross section of a friction stir spot weld and (b) Geometry of the weld bonded area, x: nugget thickness and y: the thickness of the upper sheet. Highlights: → Welding parameters affect the FSSW nugget formation and the strength of the joint. → Melting of polyethylene occurred in the vicinity of the tool pin. → The joint that fractures with a pull nugget failure mode has a higher strength. -- Abstract: Friction stir spot welding parameters affect the weld strength of thermoplastics, such as high density polyethylene (HDPE) sheets. The effects of the welding parameters on static strength of friction stir spot welds of high density polyethylene sheets were investigated. For maximizing the weld strength, the selection of welding parameters is very important. In lap-shear tests two fracture modes were observed; cross nugget failure and pull nugget failure. The tool rotational speed, tool plunge depth and dwell time were determined to be important in the joint formation and its strength. The joint which had a better strength fails with a pull nugget failure morphology. Weld cross section image analysis of the joints were done with a video spectral comparator. The plunge rate of the tool was determined to have a negligible effect on friction stir spot welding.

  10. Empirical Analysis and Modeling of Stop-Line Crossing Time and Speed at Signalized Intersections

    Directory of Open Access Journals (Sweden)

    Keshuang Tang

    2016-12-01

    Full Text Available In China, a flashing green (FG indication of 3 s followed by a yellow (Y indication of 3 s is commonly applied to end the green phase at signalized intersections. Stop-line crossing behavior of drivers during such a phase transition period significantly influences safety performance of signalized intersections. The objective of this study is thus to empirically analyze and model drivers’ stop-line crossing time and speed in response to the specific phase transition period of FG and Y. High-resolution trajectories for 1465 vehicles were collected at three rural high-speed intersections with a speed limit of 80 km/h and two urban intersections with a speed limit of 50 km/h in Shanghai. With the vehicle trajectory data, statistical analyses were performed to look into the general characteristics of stop-line crossing time and speed at the two types of intersections. A multinomial logit model and a multiple linear regression model were then developed to predict the stop-line crossing patterns and speeds respectively. It was found that the percentage of stop-line crossings during the Y interval is remarkably higher and the stop-line crossing time is approximately 0.7 s longer at the urban intersections, as compared with the rural intersections. In addition, approaching speed and distance to the stop-line at the onset of FG as well as area type significantly affect the percentages of stop-line crossings during the FG and Y intervals. Vehicle type and stop-line crossing pattern were found to significantly influence the stop-line crossing speed, in addition to the above factors. The red-light-running seems to occur more frequently at the large intersections with a long cycle length.

  11. Timing measurements of some tracking algorithms and suitability of FPGA's to improve the execution speed

    CERN Document Server

    Khomich, A; Kugel, A; Männer, R; Müller, M; Baines, J T M

    2003-01-01

    Some of track reconstruction algorithms which are common to all B-physics channels and standard RoI processing have been tested for execution time and assessed for suitability for speed-up by using FPGA coprocessor. The studies presented in this note were performed in the C/C++ framework, CTrig, which was the fullest set of algorithms available at the time of study For investigation of possible speed-up of algorithms most time consuming parts of TRT-LUT was implemented in VHDL for running in FPGA coprocessor board MPRACE. MPRACE (Reconfigurable Accelerator / Computing Engine) is an FPGA-Coprocessor based on Xilinx Virtex-2 FPGA and made as 64Bit/66MHz PCI card developed at the University of Mannheim. Timing measurements results for a TRT Full Scan algorithm executed on the MPRACE are presented here as well. The measurement results show a speed-up factor of ~2 for this algorithm.

  12. Resolving Nonstationary Spectral Information in Wind Speed Time Series Using the Hilbert-Huang Transform

    DEFF Research Database (Denmark)

    Vincent, Claire Louise; Giebel, Gregor; Pinson, Pierre

    2010-01-01

    a 4-yr time series of 10-min wind speed observations. An adaptive spectral analysis method called the Hilbert–Huang transform is chosen for the analysis, because the nonstationarity of time series of wind speed observations means that they are not well described by a global spectral analysis method...... such as the Fourier transform. The Hilbert–Huang transform is a local method based on a nonparametric and empirical decomposition of the data followed by calculation of instantaneous amplitudes and frequencies using the Hilbert transform. The Hilbert–Huang transformed 4-yr time series is averaged and summarized...

  13. Gimballed Shoulders for Friction Stir Welding

    Science.gov (United States)

    Carter, Robert; Lawless, Kirby

    2008-01-01

    In a proposed improvement of tooling for friction stir welding, gimballed shoulders would supplant shoulders that, heretofore, have been fixedly aligned with pins. The proposal is especially relevant to self-reacting friction stir welding. Some definitions of terms, recapitulated from related prior NASA Tech Briefs articles, are prerequisite to a meaningful description of the proposed improvement. In friction stir welding, one uses a tool that includes (1) a rotating shoulder on top (or front) of the workpiece and (2) a pin that rotates with the shoulder and protrudes from the shoulder into the depth of the workpiece. In conventional friction stir welding, the main axial force exerted by the tool on the workpiece is reacted through a ridged backing anvil under (behind) the workpiece. When conventional friction stir welding is augmented with an auto-adjustable pin-tool (APT) capability, the depth of penetration of the pin into the workpiece is varied in real time by a position- or forcecontrol system that extends or retracts the pin as needed to obtain the desired effect. In self-reacting (also known as self-reacted) friction stir welding as practiced heretofore, there are two shoulders: one on top (or front) and one on the bottom (or back) of the workpiece. In this case, a threaded shaft protrudes from the tip of the pin to beyond the back surface of the workpiece. The back shoulder is held axially in place against tension by a nut on the threaded shaft. Both shoulders rotate with the pin and remain aligned coaxially with the pin. The main axial force exerted on the workpiece by the tool and front shoulder is reacted through the back shoulder and the threaded shaft into the friction-stir-welding machine head, so that a backing anvil is no longer needed. A key transmits torque between the bottom shoulder and the threaded shaft, so that the bottom shoulder rotates with the shaft. This concludes the prerequisite definitions of terms.

  14. Subsidence Evaluation of High-Speed Railway in Shenyang Based on Time-Series Insar

    Science.gov (United States)

    Zhang, Yun; Wei, Lianhuan; Li, Jiayu; Liu, Shanjun; Mao, Yachun; Wu, Lixin

    2018-04-01

    More and more high-speed railway are under construction in China. The slow settlement along high-speed railway tracks and newly-built stations would lead to inhomogeneous deformation of local area, and the accumulation may be a threat to the safe operation of high-speed rail system. In this paper, surface deformation of the newly-built high-speed railway station as well as the railway lines in Shenyang region will be retrieved by time series InSAR analysis using multi-orbit COSMO-SkyMed images. This paper focuses on the non-uniform subsidence caused by the changing of local environment along the railway. The accuracy of the settlement results can be verified by cross validation of the results obtained from two different orbits during the same period.

  15. There Is Time for Calculation in Speed Chess, and Calculation Accuracy Increases With Expertise.

    Science.gov (United States)

    Chang, Yu-Hsuan A; Lane, David M

    2016-01-01

    The recognition-action theory of chess skill holds that expertise in chess is due primarily to the ability to recognize familiar patterns of pieces. Despite its widespread acclaim, empirical evidence for this theory is indirect. One source of indirect evidence is that there is a high correlation between speed chess and standard chess. Assuming that there is little or no time for calculation in speed chess, this high correlation implies that calculation is not the primary factor in standard chess. Two studies were conducted analyzing 100 games of speed chess. In Study 1, we examined the distributions of move times, and the key finding was that players often spent considerable time on a few moves. Moreover, stronger players were more likely than weaker players to do so. Study 2 examined skill differences in calculation by examining poor moves. The stronger players made proportionally fewer blunders (moves that a 2-ply search would have revealed to be errors). Overall, the poor moves made by the weaker players would have required a less extensive search to be revealed as poor moves than the poor moves made by the stronger players. Apparently, the stronger players are searching deeper and more accurately. These results are difficult to reconcile with the view that speed chess does not allow players time to calculate extensively and call into question the assertion that the high correlation between speed chess and standard chess supports recognition-action theory.

  16. A controlled study on batted ball speed and available pitcher reaction time in slowpitch softball

    Science.gov (United States)

    McDowell, M; Ciocco, M

    2005-01-01

    Objectives: To investigate safety risks in slowpitch softball by conducting laboratory and experimental studies on the performance of high tech softball bats with polyurethane softballs. To compare the results with the recommended safety standards. Methods: ASTM standard compression testing of seven softball models was conducted. Using these seven softball models, bat/ball impact testing was performed using seven adult male softball players and six high tech softball bat models to determine mean batted ball speeds. Over 500 bat/ball impact measurements were recorded and analysed. Available pitcher reaction time was calculated from the mean batted ball speed measurements. Results: According to the United States Specialty Sports Association and the Amateur Softball Association, the maximum initial batted ball speed should be 137.2 km/h, which corresponds to a minimum pitcher reaction time of 0.420 second. These experiments produced mean batted ball speeds of 134.0–159.7 km/h, which correspond to available pitcher reaction times of 0.409–0.361 second. Conclusion: The use of high tech softball bats with polyurethane softballs can result in batted ball speeds that exceed the recommended safety limits, which correspond to decreased available pitcher reaction times. PMID:15793092

  17. Time series analysis of wind speed using VAR and the generalized impulse response technique

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, Bradley T. [Area of Information Systems and Quantitative Sciences, Rawls College of Business and Wind Science and Engineering Research Center, Texas Tech University, Lubbock, TX 79409-2101 (United States); Kruse, Jamie Brown [Center for Natural Hazard Research, East Carolina University, Greenville, NC (United States); Schroeder, John L. [Department of Geosciences and Wind Science and Engineering Research Center, Texas Tech University, Lubbock, TX (United States); Smith, Douglas A. [Department of Civil Engineering and Wind Science and Engineering Research Center, Texas Tech University, Lubbock, TX (United States)

    2007-03-15

    This research examines the interdependence in time series wind speed data measured in the same location at four different heights. A multiple-equation system known as a vector autoregression is proposed for characterizing the time series dynamics of wind. Additionally, the recently developed method of generalized impulse response analysis provides insight into the cross-effects of the wind series and their responses to shocks. Findings are based on analysis of contemporaneous wind speed time histories taken at 13, 33, 70 and 160 ft above ground level with a sampling rate of 10 Hz. The results indicate that wind speeds measured at 70 ft was the most variable. Further, the turbulence persisted longer at the 70-ft measurement than at the other heights. The greatest interdependence is observed at 13 ft. Gusts at 160 ft led to the greatest persistence to an 'own' shock and led to greatest persistence in the responses of the other wind series. (author)

  18. High-Powered, Ultrasonically Assisted Thermal Stir Welding

    Science.gov (United States)

    Ding, Robert

    2013-01-01

    This method is a solid-state weld process capable of joining metallic alloys without melting. The weld workpieces to be joined by thermal stir welding (TSW) are drawn, by heavy forces, between containment plates past the TSW stir tool that then causes joining of the weld workpiece. TSW is similar to friction stir welding (FSW) in that material is heated into a plastic state (not melted) and stirred using a stir rod. The FSW pin tool is an integrated geometrical structure consisting of a large-diameter shoulder, and a smaller-diameter stir pin protruding from the shoulder. When the pin is plunged into a weld workpiece, the shoulder spins on the surface of the weld workpiece, thus inducing frictional heat into the part. The pin stirs the fraying surfaces of the weld joint, thus joining the weld workpiece into one structure. The shoulder and stir pin of the FSW pin tool must rotate together at a desired rotational speed. The induced frictional energy control and stir pin control of the pin tool cannot be de-coupled. The two work as one integrated unit. TSW, on the other hand, de-couples the heating and stirring of FSW, and allows for independent control of each process element. A uniquely designed induction coil heats the weld workpiece to a desired temperature, and once heated, the part moves into a stir rod whose RPM is also independently controlled. As the weld workpiece moves into the stir rod, the piece is positioned, or sandwiched, between upper and lower containment plates. The plate squeezes together, thus compressing the upper and lower surfaces of the weld workpiece. This compressive force, also called consolidation force, consolidates the plastic material within the weld nugget material as it is being stirred by the stir rod. The stir rod is positioned through the center of the top containment plate and protrudes midway through the opposite lower containment plate where it is mechanically captured. The upper and lower containment plates are separated by a

  19. High speed real-time wavefront processing system for a solid-state laser system

    Science.gov (United States)

    Liu, Yuan; Yang, Ping; Chen, Shanqiu; Ma, Lifang; Xu, Bing

    2008-03-01

    A high speed real-time wavefront processing system for a solid-state laser beam cleanup system has been built. This system consists of a core2 Industrial PC (IPC) using Linux and real-time Linux (RT-Linux) operation system (OS), a PCI image grabber, a D/A card. More often than not, the phase aberrations of the output beam from solid-state lasers vary fast with intracavity thermal effects and environmental influence. To compensate the phase aberrations of solid-state lasers successfully, a high speed real-time wavefront processing system is presented. Compared to former systems, this system can improve the speed efficiently. In the new system, the acquisition of image data, the output of control voltage data and the implementation of reconstructor control algorithm are treated as real-time tasks in kernel-space, the display of wavefront information and man-machine conversation are treated as non real-time tasks in user-space. The parallel processing of real-time tasks in Symmetric Multi Processors (SMP) mode is the main strategy of improving the speed. In this paper, the performance and efficiency of this wavefront processing system are analyzed. The opened-loop experimental results show that the sampling frequency of this system is up to 3300Hz, and this system can well deal with phase aberrations from solid-state lasers.

  20. Time Dilation And Changes Of Material Properties Of An Atom (Body) In Speed Of Near Light Speed Based On The ``Substantial Motion'' Theory of Iranian Philosopher, Mulla Sadra

    Science.gov (United States)

    Gholibeigian, Hassan; Gholibeigian, Kazem

    Iranian Philosopher, Sadr-ol-Moteallehin (1571-1640) said in his famous book, Asfar: ''the Universe moves in its entity... and time is its fourth dimension, and time is magnitude of the motion (momentum) of the matter in its entity''. In other words, time for each atom is momentum of its involved fundamental particles, [APS March Meeting 2015, abstract #V1.023]. When an atom (body) moves in speed of near light speed, speed of its involved fundamental particles become slow, and consequently the magnitude of its momentum (time) will decrease. On the other hands, when the spin and orbital angular momentum of an atom changed, it means that its properties, mass, strength of its electromagnetic field and its interaction with momentum changed. As a result, each atom (body) which moves in light speed, lower or faster than that, will get a new identity and vice versa. The special relativity can be the special form of this theory. In this way, black holes will be lighter than their involved masses at rest (a paradox with general relativity). Dark matter/energy may be created at first in B.B (Convection Bang) [AGU Fall Meeting 2015, abstract ID: 58425], in more than light speed, so, if we speed protons to more than light speed (in LHC), we may see dark mater/energy in new space-time. AmirKabir University of Technology.

  1. Low temperature friction stir welding of P91 steel

    Directory of Open Access Journals (Sweden)

    Prasad Rao Kalvala

    2016-08-01

    Full Text Available Bead-on-plate friction stir welds were made on P91 alloy with low and high rotational speeds (100 and 1000 RPM to study their effects on weld microstructural changes and impression creep behavior. Temperatures experienced by the stir zone were recorded at the weld tool tip. Different zones of welds were characterized for their microstructural changes, hardness and creep behavior (by impression creep tests. The results were compared with submerged arc fusion weld. Studies revealed that the stir zone temperature with 100 RPM was well below Ac1 temperature of P91 steel while it was above Ac3 with 1000 RPM. The results suggest that the microstructural degradation in P91 welds can be controlled by low temperature friction stir welding technique.

  2. Pacing Strategy, Muscle Fatigue, and Technique in 1500-m Speed-Skating and Cycling Time Trials.

    Science.gov (United States)

    Stoter, Inge K; MacIntosh, Brian R; Fletcher, Jared R; Pootz, Spencer; Zijdewind, Inge; Hettinga, Florentina J

    2016-04-01

    To evaluate pacing behavior and peripheral and central contributions to muscle fatigue in 1500-m speed-skating and cycling time trials when a faster or slower start is instructed. Nine speed skaters and 9 cyclists, all competing at regional or national level, performed two 1500-m time trials in their sport. Athletes were instructed to start faster than usual in 1 trial and slower in the other. Mean velocity was measured per 100 m. Blood lactate concentrations were measured. Maximal voluntary contraction (MVC), voluntary activation (VA), and potentiated twitch (PT) of the quadriceps muscles were measured to estimate central and peripheral contributions to muscle fatigue. In speed skating, knee, hip, and trunk angles were measured to evaluate technique. Cyclists showed a more explosive start than speed skaters in the fast-start time trial (cyclists performed first 300 m in 24.70 ± 1.73 s, speed skaters in 26.18 ± 0.79 s). Both trials resulted in reduced MVC (12.0% ± 14.5%), VA (2.4% ± 5.0%), and PT (25.4% ± 15.2%). Blood lactate concentrations after the time trial and the decrease in PT were greater in the fast-start than in the slow-start trial. Speed skaters showed higher trunk angles in the fast-start than in the slow-start trial, while knee angles remained similar. Despite similar instructions, behavioral adaptations in pacing differed between the 2 sports, resulting in equal central and peripheral contributions to muscle fatigue in both sports. This provides evidence for the importance of neurophysiological aspects in the regulation of pacing. It also stresses the notion that optimal pacing needs to be studied sport specifically, and coaches should be aware of this.

  3. Wind Speed Prediction with Wavelet Time Series Based on Lorenz Disturbance

    Directory of Open Access Journals (Sweden)

    ZHANG, Y.

    2017-08-01

    Full Text Available Due to the sustainable and pollution-free characteristics, wind energy has been one of the fastest growing renewable energy sources. However, the intermittent and random fluctuation of wind speed presents many challenges for reliable wind power integration and normal operation of wind farm. Accurate wind speed prediction is the key to ensure the safe operation of power system and to develop wind energy resources. Therefore, this paper has presented a wavelet time series wind speed prediction model based on Lorenz disturbance. Therefore, in this paper, combined with the atmospheric dynamical system, a wavelet-time series improved wind speed prediction model based on Lorenz disturbance is proposed and the wind turbines of different climate types in Spain and China are used to simulate the disturbances of Lorenz equations with different initial values. The prediction results show that the improved model can effectively correct the preliminary prediction of wind speed, improving the prediction. In a word, the research work in this paper will be helpful to arrange the electric power dispatching plan and ensure the normal operation of the wind farm.

  4. Chaotic characteristics enhanced by impeller of perturbed six-bent-bladed turbine in stirred tank

    Directory of Open Access Journals (Sweden)

    Deyu Luan

    Full Text Available The fundamental way of improving the mixing efficiency is to induce the chaotic flow in a stirred vessel. The impeller form plays an important role for changing the structure of flow field and realizing chaotic mixing. Based on the velocity time series acquired by the experiment of particle image velocimetry (PIV, with the software Matlab, the macro-instability (MI, largest Lyapunov exponent (LLE, and Kolmogorov entropy in the water stirred tank is investigated respectively with the impeller of perturbed six-bent-bladed turbine (6PBT. The results show that the MI characteristics are obvious and two peak values of MI frequency are observed at the speed N = 60 rpm. With the increasing speed (more than 100 rpm, the peak characteristics of MI frequency disappear and a multi-scale wavelet structure of characterizing the chaotic flow field appears. Moreover, under the speed N = 60 rpm, the LLE is less than 0 and Kolmogorov entropy is 0, which means that the flow field is in the periodic moving state. As the speed is increased to more than 100 rpm, the LLE and Kolmogorov entropy are all more than 0, which indicates that the flow field goes into the chaotic mixing. When the speed reaches up to about 210 rpm, both of the LLE and Kolmogorov entropy achieve the optimum values, which will result in an excellent chaos with the highest mixing efficient. So it is feasible that the MI frequency, the LLE and the Kolmogorov entropy can be used to analyze the flow field characteristics in a stirred tank. The research results promote the understanding of the chaotic mixing mechanism and provide a theoretical reference for the development of new type impeller. Keywords: Macro-instability, The largest Lyapunov exponent, Kolmogorov entropy, The impeller of perturbed six-bent-bladed turbine, Chaotic mixing, PIV

  5. CMOS continuous-time adaptive equalizers for high-speed serial links

    CERN Document Server

    Gimeno Gasca, Cecilia; Aldea Chagoyen, Concepción

    2015-01-01

    This book introduces readers to the design of adaptive equalization solutions integrated in standard CMOS technology for high-speed serial links. Since continuous-time equalizers offer various advantages as an alternative to discrete-time equalizers at multi-gigabit rates, this book provides a detailed description of continuous-time adaptive equalizers design - both at transistor and system levels-, their main characteristics and performances. The authors begin with a complete review and analysis of the state of the art of equalizers for wireline applications, describing why they are necessary, their types, and their main applications. Next, theoretical fundamentals of continuous-time adaptive equalizers are explored. Then, new structures are proposed to implement the different building blocks of the adaptive equalizer: line equalizer, loop-filters, power comparator, etc.  The authors demonstrate the design of a complete low-power, low-voltage, high-speed, continuous-time adaptive equalizer. Finally, a cost-...

  6. The Measurement of Time: Children's Construction of Transitivity, Unit Iteration, and Conservation of Speed.

    Science.gov (United States)

    Long, Kathy; Kamii, Constance

    2001-01-01

    Interviews 120 children in kindergarten and grades 2, 4, and 6 with five Piagetian tasks to determine the grade level at which most have constructed transitive reasoning, unit iteration, and conservation of speed. Indicates that construction of the logic necessary to make sense of the measurement of time is generally not complete before sixth…

  7. Time-of-Flight Measurement of the Speed of Sound in a Metal Bar

    Science.gov (United States)

    Ganci, Salvatore

    2016-01-01

    A simple setup was designed for a "time-of-flight" measurement of the sound speed in a metal bar. The experiment requires low cost components and is very simple to understand by students. A good use of it is as a demonstration experiment.

  8. Slow Speed--Fast Motion: Time-Lapse Recordings in Physics Education

    Science.gov (United States)

    Vollmer, Michael; Möllmann, Klaus-Peter

    2018-01-01

    Video analysis with a 30 Hz frame rate is the standard tool in physics education. The development of affordable high-speed-cameras has extended the capabilities of the tool for much smaller time scales to the 1 ms range, using frame rates of typically up to 1000 frames s[superscript -1], allowing us to study transient physics phenomena happening…

  9. The effects of disjunct sampling and averaging time on maximum mean wind speeds

    DEFF Research Database (Denmark)

    Larsén, Xiaoli Guo; Mann, J.

    2006-01-01

    Conventionally, the 50-year wind is calculated on basis of the annual maxima of consecutive 10-min averages. Very often, however, the averages are saved with a temporal spacing of several hours. We call it disjunct sampling. It may also happen that the wind speeds are averaged over a longer time...

  10. Simultaneous Optimization of Container Ship Sailing Speed and Container Routing with Transit Time Restrictions

    DEFF Research Database (Denmark)

    Karsten, Christian Vad; Røpke, Stefan; Pisinger, David

    We introduce a decision support tool for liner shipping companies to optimally determine the sailing speed and needed fleet for a global network. As a novelty we incorporate cargo routing decisions with tight transit time restrictions on each container such that we get a realistic picture...

  11. Flipping the analytical coin : closing the information flow loop in high speed (real time) analysis

    NARCIS (Netherlands)

    K.E. Shahroudi

    1997-01-01

    textabstractAnalysis modules tend to be set up as one way flow of information, i.e a clear distinction between cause and effect or input and output. However, as the speed of analysis approaches real time (or faster than movie rate), it becomes increasingly difficult for an external user to

  12. The role of reading time complexity and reading speed in text comprehension

    DEFF Research Database (Denmark)

    Wallot, Sebastian; O'Brien, Beth; Haussmann, Anna

    2014-01-01

    results show that recurrence metrics that quantify the degree of temporal structure in reading times yield better prediction of text comprehension compared to reading speed. However, the results for fractal metrics are less clear. Furthermore, prediction of text comprehension is generally strongest...

  13. Do testing effects change over time? Insights from immediate and delayed retrieval speed

    NARCIS (Netherlands)

    Broek, G.S.E. van den; Segers, P.C.J.; Takashima, A.; Verhoeven, L.T.W.

    2014-01-01

    Retrieving information from memory improves recall accuracy more than continued studying, but this testing effect often only becomes visible over time. In contrast, the present study documents testing effects on recall speed both immediately after practice and after a delay. A total of 40

  14. Positivity-preserving space-time CE/SE scheme for high speed flows

    KAUST Repository

    Shen, Hua

    2017-03-02

    We develop a space-time conservation element and solution element (CE/SE) scheme using a simple slope limiter to preserve the positivity of the density and pressure in computations of inviscid and viscous high-speed flows. In general, the limiter works with all existing CE/SE schemes. Here, we test the limiter on a central Courant number insensitive (CNI) CE/SE scheme implemented on hybrid unstructured meshes. Numerical examples show that the proposed limiter preserves the positivity of the density and pressure without disrupting the conservation law; it also improves robustness without losing accuracy in solving high-speed flows.

  15. Positivity-preserving space-time CE/SE scheme for high speed flows

    KAUST Repository

    Shen, Hua; Parsani, Matteo

    2017-01-01

    We develop a space-time conservation element and solution element (CE/SE) scheme using a simple slope limiter to preserve the positivity of the density and pressure in computations of inviscid and viscous high-speed flows. In general, the limiter works with all existing CE/SE schemes. Here, we test the limiter on a central Courant number insensitive (CNI) CE/SE scheme implemented on hybrid unstructured meshes. Numerical examples show that the proposed limiter preserves the positivity of the density and pressure without disrupting the conservation law; it also improves robustness without losing accuracy in solving high-speed flows.

  16. Friction Stir Welding

    Science.gov (United States)

    Nunes, Arthur C., Jr.

    2008-01-01

    Friction stir welding (FSW) is a solid state welding process invented in 1991 at The Welding Institute in the United Kingdom. A weld is made in the FSW process by translating a rotating pin along a weld seam so as to stir the sides of the seam together. FSW avoids deleterious effects inherent in melting and promises to be an important welding process for any industries where welds of optimal quality are demanded. This article provides an introduction to the FSW process. The chief concern is the physical effect of the tool on the weld metal: how weld seam bonding takes place, what kind of weld structure is generated, potential problems, possible defects for example, and implications for process parameters and tool design. Weld properties are determined by structure, and the structure of friction stir welds is determined by the weld metal flow field in the vicinity of the weld tool. Metal flow in the vicinity of the weld tool is explained through a simple kinematic flow model that decomposes the flow field into three basic component flows: a uniform translation, a rotating solid cylinder, and a ring vortex encircling the tool. The flow components, superposed to construct the flow model, can be related to particular aspects of weld process parameters and tool design; they provide a bridge to an understanding of a complex-at-first-glance weld structure. Torques and forces are also discussed. Some simple mathematical models of structural aspects, torques, and forces are included.

  17. Detector dead-time effects and paralyzability in high-speed quantum key distribution

    International Nuclear Information System (INIS)

    Rogers, Daniel J; Bienfang, Joshua C; Nakassis, Anastase; Xu Hai; Clark, Charles W

    2007-01-01

    Recent advances in quantum key distribution (QKD) have given rise to systems that operate at transmission periods significantly shorter than the dead times of their component single-photon detectors. As systems continue to increase in transmission rate, security concerns associated with detector dead times can limit the production rate of sifted bits. We present a model of high-speed QKD in this limit that identifies an optimum transmission rate for a system with given link loss and detector response characteristics

  18. Joint optimization of green vehicle scheduling and routing problem with time-varying speeds

    Science.gov (United States)

    Zhang, Dezhi; Wang, Xin; Ni, Nan; Zhang, Zhuo

    2018-01-01

    Based on an analysis of the congestion effect and changes in the speed of vehicle flow during morning and evening peaks in a large- or medium-sized city, the piecewise function is used to capture the rules of the time-varying speed of vehicles, which are very important in modelling their fuel consumption and CO2 emission. A joint optimization model of the green vehicle scheduling and routing problem with time-varying speeds is presented in this study. Extra wages during nonworking periods and soft time-window constraints are considered. A heuristic algorithm based on the adaptive large neighborhood search algorithm is also presented. Finally, a numerical simulation example is provided to illustrate the optimization model and its algorithm. Results show that, (1) the shortest route is not necessarily the route that consumes the least energy, (2) the departure time influences the vehicle fuel consumption and CO2 emissions and the optimal departure time saves on fuel consumption and reduces CO2 emissions by up to 5.4%, and (3) extra driver wages have significant effects on routing and departure time slot decisions. PMID:29466370

  19. [Optimization of stir-baking with vinegar technology for Curcumae Radix by orthogonal test].

    Science.gov (United States)

    Shi, Dianhua; Su, Benzheng; Sun, Lili; Zhang, Jun; Qu, Yongsheng

    2011-05-01

    To optimize the stir-baking with vinegar technology for Curcumae Radix. The intrinsic quality (the content of Curcumin) and traditional outward appearance were chosen as indexes. The best technology was determined by orthogonal test L9 (3(4)). The factors of the moistening time, stir-baking temperature and stir-baking time were investigated. The optimal technology was as follows: the quantity of vinegar was 10%, the moistening time was 10 min, the stir-baking temperature was 130 degrees C and the stir-baking time was 10 min. The optimal stir-baking with vinegar technology for Curcumae Radix is reasonable, which can be used to guide the standardized production of Curcumae Radix stir-baked with vinegar.

  20. Weld Nugget Temperature Control in Thermal Stir Welding

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2014-01-01

    A control system for a thermal stir welding system is provided. The control system includes a sensor and a controller. The sensor is coupled to the welding system's containment plate assembly and generates signals indicative of temperature of a region adjacent and parallel to the welding system's stir rod. The controller is coupled to the sensor and generates at least one control signal using the sensor signals indicative of temperature. The controller is also coupled to the welding system such that at least one of rotational speed of the stir rod, heat supplied by the welding system's induction heater, and feed speed of the welding system's weld material feeder are controlled based on the control signal(s).

  1. Heat Control via Torque Control in Friction Stir Welding

    Science.gov (United States)

    Venable, Richard; Colligan, Kevin; Knapp, Alan

    2004-01-01

    In a proposed advance in friction stir welding, the torque exerted on the workpiece by the friction stir pin would be measured and controlled in an effort to measure and control the total heat input to the workpiece. The total heat input to the workpiece is an important parameter of any welding process (fusion or friction stir welding). In fusion welding, measurement and control of heat input is a difficult problem. However, in friction stir welding, the basic principle of operation affords the potential of a straightforward solution: Neglecting thermal losses through the pin and the spindle that supports it, the rate of heat input to the workpiece is the product of the torque and the speed of rotation of the friction stir weld pin and, hence, of the spindle. Therefore, if one acquires and suitably processes data on torque and rotation and controls the torque, the rotation, or both, one should be able to control the heat input into the workpiece. In conventional practice in friction stir welding, one uses feedback control of the spindle motor to maintain a constant speed of rotation. According to the proposal, one would not maintain a constant speed of rotation: Instead, one would use feedback control to maintain a constant torque and would measure the speed of rotation while allowing it to vary. The torque exerted on the workpiece would be estimated as the product of (1) the torque-multiplication ratio of the spindle belt and/or gear drive, (2) the force measured by a load cell mechanically coupled to the spindle motor, and (3) the moment arm of the load cell. Hence, the output of the load cell would be used as a feedback signal for controlling the torque (see figure).

  2. Relationship between coronal holes and high speed streams at L1: arrival times, durations, and intensities

    Science.gov (United States)

    Luo, B.; Bu, X.; Liu, S.; Gong, J.

    2017-12-01

    Coronal holes are sources of high-speed steams (HSS) of solar wind. When coronal holes appear at mid/low latitudes on the Sun, consequential HSSs may impact Earth and cause recurrent geospace environment disturbances, such as geomagnetic storms, relativistic electron enhancements at the geosynchronous orbit, and thermosphere density enhancements. Thus, it is of interests for space weather forecasters to predict when (arrival times), how long (time durations), and how severe (intensities) HSSs may impact Earth when they notice coronal holes on the sun and are anticipating their geoeffectiveness. In this study, relationship between coronal holes and high speed streams will be statistically investigated. Several coronal hole parameters, including passage times of solar central meridian, coronal hole longitudinal widths, intensities reflected by mean brightness, are derived using Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) images for years 2011 to 2016. These parameters will be correlated with in-situ solar wind measurements measured at the L1 point by the ACE spacecraft, which can give some results that are useful for space weather forecaster in predicting the arrival times, durations, and intensities of coronal hole high-speed streams in about 3 days advance.

  3. Versatile real-time interferometer phase-detection system using high-speed digital techniques

    International Nuclear Information System (INIS)

    Mendell, D.S.; Willett, G.W.

    1977-01-01

    This paper describes the basic design and philosophy of a versatile real-time interferometer phase-detection system to be used on the 2XIIB and TMX magnetic-fusion experiments at Lawrence Livermore Laboratory. This diagnostics system is a satellite to a host computer and uses high-speed emitter-coupled logic techniques to derive data on real-time phase relationships. The system's input signals can be derived from interferometer outputs over a wide range of reference frequencies. An LSI-11 microcomputer is the interface between the high-speed phase-detection logic, buffer memory, human interaction, and host computer. Phase data on a storage CRT is immediately displayed after each experimental fusion shot. An operator can interrogate this phase data more closely from an interactive control panel, and the host computer can be simultaneously examining the system's buffer memory or arming the system for the next shot

  4. Optimizing Ship Speed to Minimize Total Fuel Consumption with Multiple Time Windows

    Directory of Open Access Journals (Sweden)

    Jae-Gon Kim

    2016-01-01

    Full Text Available We study the ship speed optimization problem with the objective of minimizing the total fuel consumption. We consider multiple time windows for each port call as constraints and formulate the problem as a nonlinear mixed integer program. We derive intrinsic properties of the problem and develop an exact algorithm based on the properties. Computational experiments show that the suggested algorithm is very efficient in finding an optimal solution.

  5. Time dependent shear stress and temperature distribution over an insulated flat plate moving at hypersonic speed.

    Science.gov (United States)

    Rodkiewicz, C. M.; Gupta, R. N.

    1971-01-01

    The laminar two-dimensional flow over a stepwise accelerated flat plate moving with hypersonic speed at zero angle of attack is analysed. The governing equations in the self-similar form are linearized and solved numerically for small times. The solutions obtained are the deviations of the velocity and the temperature profiles from those of steady state. The presented results may be used to find the first order boundary layer induced pressure on the plate.

  6. Testing and Validation of Timing Properties for High Speed Digital Cameras - A Best Practices Guide

    Science.gov (United States)

    2016-07-27

    range, and frame rate get all the press when it comes to high-speed video viewed in Range Control; however, most optical data is practically...introduction of hydraulic and electrically-driven mount servo systems  The replacement of fixed optics sites with remotely-controlled mobile systems  The...support (e.g., VendorX Timing Tests with staggered 10-μs pulse sequence). (5) Select Press to Locate Board ID. The Define Board ID file should

  7. A comparison of various forecasting techniques applied to mean hourly wind speed time series

    Energy Technology Data Exchange (ETDEWEB)

    Sfetsos, A. [7 Pirsou Street, Athens (Greece)

    2000-09-01

    This paper presents a comparison of various forecasting approaches, using time series analysis, on mean hourly wind speed data. In addition to the traditional linear (ARMA) models and the commonly used feed forward and recurrent neural networks, other approaches are also examined including the Adaptive Neuro-Fuzzy Inference Systems (ANFIS) and Neural Logic Networks. The developed models are evaluated for their ability to produce accurate and fast forecasts. (Author)

  8. Microstructure Evolution during Friction Stir Spot Welding of TRIP Steel

    DEFF Research Database (Denmark)

    Lomholt, Trine Colding; Pantleon, Karen; Somers, Marcel A. J.

    2010-01-01

    In this study, the feasibility of friction stir spot welding of TRIP steel is investigated. In addition to manufacturing successful welds, the present study aims at a fundamental understanding of the mechanisms occurring at the (sub)micron scale during friction stir spot welding. As one of the ma...... electron microscopy, and electron backscatter diffraction. Microhardness measurements and lap-shear tensile tests completed the investigations of the welded samples and allow evaluation of the quality of the welds.......In this study, the feasibility of friction stir spot welding of TRIP steel is investigated. In addition to manufacturing successful welds, the present study aims at a fundamental understanding of the mechanisms occurring at the (sub)micron scale during friction stir spot welding. As one of the main...... parameters to control friction stir welding, the influence of the rotational speed of the tool was investigated. Three different rotational speeds (500 rpm, 1000 rpm and 1500 rpm, respectively) were applied. The microstructure of the welded samples was investigated with reflected light microscopy, scanning...

  9. Understanding Friction Stir Welding

    Science.gov (United States)

    Nunes, A. C., Jr.

    2018-01-01

    This Technical Memorandum explains the friction stir welding process in terms of two basic concepts: the concentration of deformation in a shear surface enveloping the tool and the composition of the overall plastic flow field around the tool from simple flow field components. It is demonstrated how weld structure may be understood and torque, drag, and lateral tool forces may be estimated using these concepts. Some discrepancies between computations and accompanying empirical data are discussed in the text. This work is intended to be helpful to engineers in diagnosing problems and advancing technology.

  10. The effect of centrifugation speed and time on pre-analytical platelet activation.

    Science.gov (United States)

    Söderström, Anna C; Nybo, Mads; Nielsen, Christian; Vinholt, Pernille J

    2016-12-01

    The results of laboratory analyses are affected by pre-analytical variables, and in particular can platelets be activated by shear handling stress and secrete granular substances. We therefore evaluated the effect of centrifugation speed and time on pre-analytical platelet activation. Citrate- and EDTA-anticoagulated blood from healthy volunteers were centrifuged at 80-10,000 g for 5-15 min to prepare plasma and platelet-rich plasma. Pre-analytical platelet activation was assessed by flow cytometric measurement of platelet P-selectin (CD62p) expression. Blood cell counts, mean platelet volume (MPV), immature platelet fraction (IPF), and platelet distribution width (PDW) were measured. Platelet aggregation in platelet-rich plasma induced by arachidonic acid (AA), ADP or thrombin receptor activator peptide-6 (TRAP) was tested by 96-well aggregometry. The median percentage of platelets expressing P-selectin in citrate- and EDTA-plasma centrifuged at 2000 g for 10 min were 43% [interquartile range (IQR), 38%-53%] and 56% (IQR, 31%-78%), respectively (p=0.82). Platelet-rich plasma prepared at 100-250 g for 10 min had significantly lower platelet P-selectin expression (11%-15%), pcentrifuged. In platelet-rich plasma, increasing centrifugation speed significantly increased platelet yield but decreased contamination from other blood cells, platelet composition was altered as platelet parameters (MPV, IPF, and PDW) was lowered. Platelet aggregation was not affected by the centrifugation speed platelet-rich plasma was prepared. Proportional to centrifugation speed, platelets in plasma and platelet-rich plasma were activated with centrifugation speed, cell content and composition changed while platelet aggregation was unaltered.

  11. Entropy of space-time outcome in a movement speed-accuracy task.

    Science.gov (United States)

    Hsieh, Tsung-Yu; Pacheco, Matheus Maia; Newell, Karl M

    2015-12-01

    The experiment reported was set-up to investigate the space-time entropy of movement outcome as a function of a range of spatial (10, 20 and 30 cm) and temporal (250-2500 ms) criteria in a discrete aiming task. The variability and information entropy of the movement spatial and temporal errors considered separately increased and decreased on the respective dimension as a function of an increment of movement velocity. However, the joint space-time entropy was lowest when the relative contribution of spatial and temporal task criteria was comparable (i.e., mid-range of space-time constraints), and it increased with a greater trade-off between spatial or temporal task demands, revealing a U-shaped function across space-time task criteria. The traditional speed-accuracy functions of spatial error and temporal error considered independently mapped to this joint space-time U-shaped entropy function. The trade-off in movement tasks with joint space-time criteria is between spatial error and timing error, rather than movement speed and accuracy. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. CFD optimization of continuous stirred-tank (CSTR) reactor for biohydrogen production.

    Science.gov (United States)

    Ding, Jie; Wang, Xu; Zhou, Xue-Fei; Ren, Nan-Qi; Guo, Wan-Qian

    2010-09-01

    There has been little work on the optimal configuration of biohydrogen production reactors. This paper describes three-dimensional computational fluid dynamics (CFD) simulations of gas-liquid flow in a laboratory-scale continuous stirred-tank reactor used for biohydrogen production. To evaluate the role of hydrodynamics in reactor design and optimize the reactor configuration, an optimized impeller design has been constructed and validated with CFD simulations of the normal and optimized impeller over a range of speeds and the numerical results were also validated by examination of residence time distribution. By integrating the CFD simulation with an ethanol-type fermentation process experiment, it was shown that impellers with different type and speed generated different flow patterns, and hence offered different efficiencies for biohydrogen production. The hydrodynamic behavior of the optimized impeller at speeds between 50 and 70 rev/min is most suited for economical biohydrogen production. Copyright 2010 Elsevier Ltd. All rights reserved.

  13. Development of embedded real-time and high-speed vision platform

    Science.gov (United States)

    Ouyang, Zhenxing; Dong, Yimin; Yang, Hua

    2015-12-01

    Currently, high-speed vision platforms are widely used in many applications, such as robotics and automation industry. However, a personal computer (PC) whose over-large size is not suitable and applicable in compact systems is an indispensable component for human-computer interaction in traditional high-speed vision platforms. Therefore, this paper develops an embedded real-time and high-speed vision platform, ER-HVP Vision which is able to work completely out of PC. In this new platform, an embedded CPU-based board is designed as substitution for PC and a DSP and FPGA board is developed for implementing image parallel algorithms in FPGA and image sequential algorithms in DSP. Hence, the capability of ER-HVP Vision with size of 320mm x 250mm x 87mm can be presented in more compact condition. Experimental results are also given to indicate that the real-time detection and counting of the moving target at a frame rate of 200 fps at 512 x 512 pixels under the operation of this newly developed vision platform are feasible.

  14. Two Machine Learning Approaches for Short-Term Wind Speed Time-Series Prediction.

    Science.gov (United States)

    Ak, Ronay; Fink, Olga; Zio, Enrico

    2016-08-01

    The increasing liberalization of European electricity markets, the growing proportion of intermittent renewable energy being fed into the energy grids, and also new challenges in the patterns of energy consumption (such as electric mobility) require flexible and intelligent power grids capable of providing efficient, reliable, economical, and sustainable energy production and distribution. From the supplier side, particularly, the integration of renewable energy sources (e.g., wind and solar) into the grid imposes an engineering and economic challenge because of the limited ability to control and dispatch these energy sources due to their intermittent characteristics. Time-series prediction of wind speed for wind power production is a particularly important and challenging task, wherein prediction intervals (PIs) are preferable results of the prediction, rather than point estimates, because they provide information on the confidence in the prediction. In this paper, two different machine learning approaches to assess PIs of time-series predictions are considered and compared: 1) multilayer perceptron neural networks trained with a multiobjective genetic algorithm and 2) extreme learning machines combined with the nearest neighbors approach. The proposed approaches are applied for short-term wind speed prediction from a real data set of hourly wind speed measurements for the region of Regina in Saskatchewan, Canada. Both approaches demonstrate good prediction precision and provide complementary advantages with respect to different evaluation criteria.

  15. Incorporating geostrophic wind information for improved space–time short-term wind speed forecasting

    KAUST Repository

    Zhu, Xinxin

    2014-09-01

    Accurate short-term wind speed forecasting is needed for the rapid development and efficient operation of wind energy resources. This is, however, a very challenging problem. Although on the large scale, the wind speed is related to atmospheric pressure, temperature, and other meteorological variables, no improvement in forecasting accuracy was found by incorporating air pressure and temperature directly into an advanced space-time statistical forecasting model, the trigonometric direction diurnal (TDD) model. This paper proposes to incorporate the geostrophic wind as a new predictor in the TDD model. The geostrophic wind captures the physical relationship between wind and pressure through the observed approximate balance between the pressure gradient force and the Coriolis acceleration due to the Earth’s rotation. Based on our numerical experiments with data from West Texas, our new method produces more accurate forecasts than does the TDD model using air pressure and temperature for 1to 6-hour-ahead forecasts based on three different evaluation criteria. Furthermore, forecasting errors can be further reduced by using moving average hourly wind speeds to fit the diurnal pattern. For example, our new method obtains between 13.9% and 22.4% overall mean absolute error reduction relative to persistence in 2-hour-ahead forecasts, and between 5.3% and 8.2% reduction relative to the best previous space-time methods in this setting.

  16. Optimizing residence time, temperature and speed to improve TMP pulp properties and reduce energy

    Energy Technology Data Exchange (ETDEWEB)

    Sabourin, M.; Xu, E.; Cort, B.; Boileau, I.; Waller, A.

    1997-04-01

    The concept of reducing energy consumption in pulp mills by increasing the disc speed of refining has been established using single disc and double disc refiners in both pilot plant and mill applications. The RTS study evaluated in this paper reviews the effect of high-speed single disc refining coupled with shortdwell-high pressure retention conditions. Coupling these variables permitted evaluation of an optimum residence time, temperature and speed (RTS) operational window. The objective of the RTS conditions to sufficiently soften the wood chips through high temperature such that the fibre is more receptive to initial defiberization at high intensity. The improved pulp from the primary refiner at high intensity could potentially demonstrate improvements in physical pulp properties at a reduced specific energy requirement. The spruce/fir RTS-TMP described here required significantly less specific energy and produced TMP with slightly improved strength properties and equivalent optical properties compared to conventional TMP pulp. Studies on the radiate pine furnish indicated that the physical pulp property/specific energy relationships could be adjusted by manipulating the residence time. 4 refs., 10 tabs., 10 figs.

  17. MOSS spectroscopic camera for imaging time resolved plasma species temperature and flow speed

    International Nuclear Information System (INIS)

    Michael, Clive; Howard, John

    2000-01-01

    A MOSS (Modulated Optical Solid-State) spectroscopic camera has been devised to monitor the spatial and temporal variations of temperatures and flow speeds of plasma ion species, the Doppler broadening measurement being made of spectroscopic lines specified. As opposed to a single channel MOSS spectrometer, the camera images light from plasma onto an array of light detectors, being mentioned 2D imaging of plasma ion temperatures and flow speeds. In addition, compared to a conventional grating spectrometer, the MOSS camera shows an excellent light collecting performance which leads to the improvement of signal to noise ratio and of time resolution. The present paper first describes basic items of MOSS spectroscopy, then follows MOSS camera with an emphasis on the optical system of 2D imaging. (author)

  18. Variable speed wind turbine control by discrete-time sliding mode approach.

    Science.gov (United States)

    Torchani, Borhen; Sellami, Anis; Garcia, Germain

    2016-05-01

    The aim of this paper is to propose a new design variable speed wind turbine control by discrete-time sliding mode approach. This methodology is designed for linear saturated system. The saturation constraint is reported on inputs vector. To this end, the back stepping design procedure is followed to construct a suitable sliding manifold that guarantees the attainment of a stabilization control objective. It is well known that the mechanisms are investigated in term of the most proposed assumptions to deal with the damping, shaft stiffness and inertia effect of the gear. The objectives are to synthesize robust controllers that maximize the energy extracted from wind, while reducing mechanical loads and rotor speed tracking combined with an electromagnetic torque. Simulation results of the proposed scheme are presented. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  19. Tracking multiple objects is limited only by object spacing, not by speed, time, or capacity.

    Science.gov (United States)

    Franconeri, S L; Jonathan, S V; Scimeca, J M

    2010-07-01

    In dealing with a dynamic world, people have the ability to maintain selective attention on a subset of moving objects in the environment. Performance in such multiple-object tracking is limited by three primary factors-the number of objects that one can track, the speed at which one can track them, and how close together they can be. We argue that this last limit, of object spacing, is the root cause of all performance constraints in multiple-object tracking. In two experiments, we found that as long as the distribution of object spacing is held constant, tracking performance is unaffected by large changes in object speed and tracking time. These results suggest that barring object-spacing constraints, people could reliably track an unlimited number of objects as fast as they could track a single object.

  20. MOSS spectroscopic camera for imaging time resolved plasma species temperature and flow speed

    Energy Technology Data Exchange (ETDEWEB)

    Michael, Clive; Howard, John [Australian National Univ., Plasma Research Laboratory, Canberra (Australia)

    2000-03-01

    A MOSS (Modulated Optical Solid-State) spectroscopic camera has been devised to monitor the spatial and temporal variations of temperatures and flow speeds of plasma ion species, the Doppler broadening measurement being made of spectroscopic lines specified. As opposed to a single channel MOSS spectrometer, the camera images light from plasma onto an array of light detectors, being mentioned 2D imaging of plasma ion temperatures and flow speeds. In addition, compared to a conventional grating spectrometer, the MOSS camera shows an excellent light collecting performance which leads to the improvement of signal to noise ratio and of time resolution. The present paper first describes basic items of MOSS spectroscopy, then follows MOSS camera with an emphasis on the optical system of 2D imaging. (author)

  1. The Planck Length and the Constancy of the Speed of Light in Five Dimensional Spacetime Parametrized with Two Time Coordinates

    DEFF Research Database (Denmark)

    Köhn, Christoph

    2017-01-01

    of additional time dimensions, we observe the existence of a minimal length scale, which we identify as the Planck scale. We derive an expression for the speed of light as a function of space and time and observe the constancy of the vacuum speed of light in the observable universe....

  2. Trading speed and accuracy by coding time: a coupled-circuit cortical model.

    Directory of Open Access Journals (Sweden)

    Dominic Standage

    2013-04-01

    Full Text Available Our actions take place in space and time, but despite the role of time in decision theory and the growing acknowledgement that the encoding of time is crucial to behaviour, few studies have considered the interactions between neural codes for objects in space and for elapsed time during perceptual decisions. The speed-accuracy trade-off (SAT provides a window into spatiotemporal interactions. Our hypothesis is that temporal coding determines the rate at which spatial evidence is integrated, controlling the SAT by gain modulation. Here, we propose that local cortical circuits are inherently suited to the relevant spatial and temporal coding. In simulations of an interval estimation task, we use a generic local-circuit model to encode time by 'climbing' activity, seen in cortex during tasks with a timing requirement. The model is a network of simulated pyramidal cells and inhibitory interneurons, connected by conductance synapses. A simple learning rule enables the network to quickly produce new interval estimates, which show signature characteristics of estimates by experimental subjects. Analysis of network dynamics formally characterizes this generic, local-circuit timing mechanism. In simulations of a perceptual decision task, we couple two such networks. Network function is determined only by spatial selectivity and NMDA receptor conductance strength; all other parameters are identical. To trade speed and accuracy, the timing network simply learns longer or shorter intervals, driving the rate of downstream decision processing by spatially non-selective input, an established form of gain modulation. Like the timing network's interval estimates, decision times show signature characteristics of those by experimental subjects. Overall, we propose, demonstrate and analyse a generic mechanism for timing, a generic mechanism for modulation of decision processing by temporal codes, and we make predictions for experimental verification.

  3. New design for photonic temporal integration with combined high processing speed and long operation time window.

    Science.gov (United States)

    Asghari, Mohammad H; Park, Yongwoo; Azaña, José

    2011-01-17

    We propose and experimentally prove a novel design for implementing photonic temporal integrators simultaneously offering a high processing bandwidth and a long operation time window, namely a large time-bandwidth product. The proposed scheme is based on concatenating in series a time-limited ultrafast photonic temporal integrator, e.g. implemented using a fiber Bragg grating (FBG), with a discrete-time (bandwidth limited) optical integrator, e.g. implemented using an optical resonant cavity. This design combines the advantages of these two previously demonstrated photonic integrator solutions, providing a processing speed as high as that of the time-limited ultrafast integrator and an operation time window fixed by the discrete-time integrator. Proof-of-concept experiments are reported using a uniform fiber Bragg grating (as the original time-limited integrator) connected in series with a bulk-optics coherent interferometers' system (as a passive 4-points discrete-time photonic temporal integrator). Using this setup, we demonstrate accurate temporal integration of complex-field optical signals with time-features as fast as ~6 ps, only limited by the processing bandwidth of the FBG integrator, over time durations as long as ~200 ps, which represents a 4-fold improvement over the operation time window (~50 ps) of the original FBG integrator.

  4. Embedded system based on a real time fuzzy motor speed controller

    Directory of Open Access Journals (Sweden)

    Ebrahim Abd El-Hamid Mohamed Ramadan

    2014-06-01

    Full Text Available This paper describes an implementation of a fuzzy logic control (FLC system and a/the conventional proportional-integral (PI controller for speed control of DC motor, based on field programmable gate array (FPGA circuit. The proposed scheme is aimed to improve the tracking performance and to eliminate the load disturbance in the speed control of DC motors. The proposed fuzzy system has been applied to a permanent magnet DC motor, via a configuration of H-bridge. The fuzzy control algorithm is designed and verified with a nonlinear model, using the MATLAB® tools. Both FLC and conventional PI controller hardware are synthesized, functionally verified and implemented using Xilinx Integrated Software Environment (ISE Version 11.1i. The real time implementation of these controllers is made on Spartan-3E FPGA starter kit (XC3S500E. The practical results showed that the proposed FLC scheme has better tracking performance than the conventional PI controller for the speed control of DC motors.

  5. Accelerated Bearing Life-time Test Rig Development for Low Speed Data Acquisition

    Directory of Open Access Journals (Sweden)

    Andreas Klausen

    2017-07-01

    Full Text Available Condition monitoring plays an important role in rotating machinery to ensure reliability of the equipment, and to detect fault conditions at an early stage. Although health monitoring methodologies have been thoroughly developed for rotating machinery, low-speed conditions often pose a challenge due to the low signal-to-noise ratio. To this aim, sophisticated algorithms that reduce noise and highlight the bearing faults are necessary to accurately diagnose machines undergoing this condition. In the development phase, sensor data from a healthy and damaged bearing rotating at low-speed is required to verify the performance of such algorithms. A test rig for performing accelerated life-time testing of small rolling element bearings is designed to collect necessary sensor data. Heavy loads at high-speed conditions are applied to the test bearing to wear it out fast. Sensor data is collected in intervals during the test to capture the degeneration features. The main objective of this paper is to provide a detailed overview for the development and analysis of this test rig. A case study with experimental vibration data is also presented to illustrate the efficacy of the developed test rig.

  6. Influence of tool geometry and process parameters on macrostructure and static strength in friction stir spot welded polyethylene sheets

    International Nuclear Information System (INIS)

    Bilici, Mustafa Kemal; Yuekler, Ahmet Irfan

    2012-01-01

    Highlights: → All velding parameters and different tool geometries have demonstrated a different effects on weld strength. → Friction stir spot welding of polyethylene mechanical scission is very important. → Metric screw the tool has a great influence on the weld strength of FSSW. -- Abstract: The effect of important welding parameters and tool properties that are effective on static strength in friction stir spot welds of polyethylene sheets were studied. Six different tool pin profiles (straight cylindrical, tapered cylindrical, threaded cylindrical, triangular, square and hexagonal) with different shoulder geometries, different pin length, pin angle and concavity angle were used to fabricate the joints. The tool rotational speed, tool plunge depth and dwell time were determined welding parameters. All the welding operations were done at the room temperature. Welding force and welding zone material temperature measurements were also done. Lap-shear tests were carried out to find the weld static strength. Weld cross section appearance observations were also done. From the experiments, the effect of pin profile, pin length, pin angle, dwell time and tool rotational speed on friction stir spot welding formation and weld strength was determined.

  7. Biotransformation of ferulic acid to vanillin in the packed bed-stirred fermentors.

    Science.gov (United States)

    Yan, Lei; Chen, Peng; Zhang, Shuang; Li, Suyue; Yan, Xiaojuan; Wang, Ningbo; Liang, Ning; Li, Hongyu

    2016-10-06

    We performed the biotransformation of ferulic acid to vanillin using Bacillus subtilis (B. subtilis) in the stirring packed-bed reactors filled with carbon fiber textiles (CFT). Scanning electron microscope (SEM), HPLC, qRT-PCR and ATP assay indicated that vanillin biotransformation is tightly related to cell growth, cellar activity and the extent of biofilm formation. The biotransformation was affected by hydraulic retention time (HRT), temperature, initial pH, stirring speed and ferulic acid concentration, and the maximum vanillin production was obtained at 20 h, 35 °C, 9.0, 200 rpm, 1.5 g/L, respectively. Repeated batch biotransformation performed under this optimized condition showed that the maximum productivity (0.047 g/L/h) and molar yield (60.43%) achieved in immobilized cell system were 1.84 and 3.61 folds higher than those achieved in free cell system. Therefore, the stirring reactor packed with CFT carrier biofilm formed by B. subtilis represented a valid biocatalytic system for the production of vanillin.

  8. Nature of tracing dimension, imaginary order of freedom and our observed time passing at constant speed

    International Nuclear Information System (INIS)

    Nagao, S

    2009-01-01

    Nature of the time and requirements to work as a time dimension are investigated. A potential scenario of the development of the universe is conceptually investigated starting from energy as vibration in multiple dimensions. A model is proposed, in which the Big Bang is a phase transition of energy from vibration in 4-dimensional space to energy distribution in 3-D surface of a 4-D sphere. The Time which we observe passing at a constant speed is not such a reference frame which we unintentionally believe to be the time, but the radius dimension of the 4-D sphere. The feature of the Dark Matter and the mystery of the Dark Energy are naturally explained from the model.

  9. Nature of tracing dimension, imaginary order of freedom and our observed time passing at constant speed

    Energy Technology Data Exchange (ETDEWEB)

    Nagao, S, E-mail: snagao@lilac.plala.or.j [Business Development and Licensing Department, Nippon Boehringer Ingelheim Co., Ltd., ThinkPark Tower, 2-1-1, Osaki, Shinagawa, Tokyo 141-6017 (Japan)

    2009-06-01

    Nature of the time and requirements to work as a time dimension are investigated. A potential scenario of the development of the universe is conceptually investigated starting from energy as vibration in multiple dimensions. A model is proposed, in which the Big Bang is a phase transition of energy from vibration in 4-dimensional space to energy distribution in 3-D surface of a 4-D sphere. The Time which we observe passing at a constant speed is not such a reference frame which we unintentionally believe to be the time, but the radius dimension of the 4-D sphere. The feature of the Dark Matter and the mystery of the Dark Energy are naturally explained from the model.

  10. A metallurgical and mechanical study on dissimilar Friction Stir welding of aluminum 1050 to brass (CuZn30)

    International Nuclear Information System (INIS)

    Esmaeili, A.; Givi, M.K. Besharati; Rajani, H.R. Zareie

    2011-01-01

    Highlights: → Brass and aluminum 1050 are joined for the first time through Friction Stir welding. → Welding parameters are optimized to obtain a sound joint. → The ultimate tensile strength of the sound joint reaches 80% of aluminum base metal. → The effect of interfacial intermetallic compounds on mechanical properties is probed. → CuZn, Cu9Al4 and CuAl2 form the majority of observed intermetallic compounds. - Abstract: In this research, the effect of Friction Stir welding parameters on mechanical and metallurgical properties of aluminum 1050/brass (70%Cu-30%Zn) joints was investigated. Optical microscopy, SEM, X-ray diffraction analysis and EDS analysis were used to probe microstructures and chemical compositions. In order to examine mechanical properties, besides hardness test, tensile strength of the welds was measured. The main parameters in this study were the tool rotational speed, offset, welding speed, and depth of the sinking pin. The maximum ultimate tensile strength of the joint reached in this research was 80% of the base metal (aluminum). Results show that the optimum parameters will yield a defect free joint arisen from a suitable material flow and a narrow multilayer intermetallic compound at interface in addition to a composite structure in the stir zone which all result in a strong joint. Also, by leaving the optimized condition, occurrence of large brass fragments and weld defects lower weld strength besides shifting fracture path from interface to the stir zone. Also, according to the results, using low rotation speed is accompanied by disappearance of interfacial intermetallic layer, whereas fast rotation will thicken this layer. Moreover, severe mechanical twining is observed in TMAZ of brass which leads to high values of hardness in this region.

  11. Real-time nanofabrication with high-speed atomic force microscopy

    International Nuclear Information System (INIS)

    Vicary, J A; Miles, M J

    2009-01-01

    The ability to follow nanoscale processes in real-time has obvious benefits for the future of material science. In particular, the ability to evaluate the success of fabrication processes in situ would be an advantage for many in the semiconductor industry. We report on the application of a previously described high-speed atomic force microscope (AFM) for nanofabrication. The specific fabrication method presented here concerns the modification of a silicon surface by locally oxidizing the region in the vicinity of the AFM tip. Oxide features were fabricated during imaging, with relative tip-sample velocities of up to 10 cm s -1 , and with a data capture rate of 15 fps.

  12. A multiple ship routing and speed optimization problem under time, cost and environmental objectives

    DEFF Research Database (Denmark)

    Wen, M.; Pacino, Dario; Kontovas, C.A.

    2017-01-01

    The purpose of this paper is to investigate a multiple ship routing and speed optimization problem under time, cost and environmental objectives. A branch and price algorithm as well as a constraint programming model are developed that consider (a) fuel consumption as a function of payload, (b......) fuel price as an explicit input, (c) freight rate as an input, and (d) in-transit cargo inventory costs. The alternative objective functions are minimum total trip duration, minimum total cost and minimum emissions. Computational experience with the algorithm is reported on a variety of scenarios....

  13. High-speed railway real-time localization auxiliary method based on deep neural network

    Science.gov (United States)

    Chen, Dongjie; Zhang, Wensheng; Yang, Yang

    2017-11-01

    High-speed railway intelligent monitoring and management system is composed of schedule integration, geographic information, location services, and data mining technology for integration of time and space data. Assistant localization is a significant submodule of the intelligent monitoring system. In practical application, the general access is to capture the image sequences of the components by using a high-definition camera, digital image processing technique and target detection, tracking and even behavior analysis method. In this paper, we present an end-to-end character recognition method based on a deep CNN network called YOLO-toc for high-speed railway pillar plate number. Different from other deep CNNs, YOLO-toc is an end-to-end multi-target detection framework, furthermore, it exhibits a state-of-art performance on real-time detection with a nearly 50fps achieved on GPU (GTX960). Finally, we realize a real-time but high-accuracy pillar plate number recognition system and integrate natural scene OCR into a dedicated classification YOLO-toc model.

  14. Evaluation of Microstructure, Mechanical Properties and Corrosion Resistance of Friction Stir-Welded Aluminum and Magnesium Dissimilar Alloys

    Science.gov (United States)

    Verma, Jagesvar; Taiwade, Ravindra V.; Sapate, Sanjay G.; Patil, Awanikumar P.; Dhoble, Ashwinkumar S.

    2017-10-01

    Microstructure, mechanical properties and corrosion resistance of dissimilar friction stir-welded aluminum and magnesium alloys were investigated by applying three different rotational speeds at two different travel speeds. Sound joints were obtained in all the conditions. The microstructure was examined by an optical and scanning electron microscope, whereas localized chemical information was studied by energy-dispersive spectroscopy. Stir zone microstructure showed mixed bands of Al and Mg with coarse and fine equiaxed grains. Grain size of stir zone reduced compared to base metals, indicated by dynamic recrystallization. More Al patches were observed in the stir zone as rotational speed increased. X-ray diffraction showed the presence of intermetallics in the stir zone. Higher tensile strength and hardness were obtained at a high rotational speed corresponding to low travel speed. Tensile fractured surface indicated brittle nature of joints. Dissimilar friction stir weld joints showed different behaviors in different corrosive environments, and better corrosion resistance was observed at a high rotational speed corresponding to low travel speed (FW3) in a sulfuric and chloride environments. Increasing travel speed did not significantly affect on microstructure, mechanical properties and corrosion resistance as much as the rotational speed.

  15. Verification of the helioseismology travel-time measurement technique and the inversion procedure for sound speed using artificial data

    Energy Technology Data Exchange (ETDEWEB)

    Parchevsky, K. V.; Zhao, J.; Hartlep, T.; Kosovichev, A. G., E-mail: akosovichev@solar.stanford.edu [Stanford University, HEPL, Stanford, CA 94305 (United States)

    2014-04-10

    We performed three-dimensional numerical simulations of the solar surface acoustic wave field for the quiet Sun and for three models with different localized sound-speed perturbations in the interior with deep, shallow, and two-layer structures. We used the simulated data generated by two solar acoustics codes that employ the same standard solar model as a background model, but utilize different integration techniques and different models of stochastic wave excitation. Acoustic travel times were measured using a time-distance helioseismology technique, and compared with predictions from ray theory frequently used for helioseismic travel-time inversions. It is found that the measured travel-time shifts agree well with the helioseismic theory for sound-speed perturbations, and for the measurement procedure with and without phase-speed filtering of the oscillation signals. This testing verifies the whole measuring-filtering-inversion procedure for static sound-speed anomalies with small amplitude inside the Sun outside regions of strong magnetic field. It is shown that the phase-speed filtering, frequently used to extract specific wave packets and improve the signal-to-noise ratio, does not introduce significant systematic errors. Results of the sound-speed inversion procedure show good agreement with the perturbation models in all cases. Due to its smoothing nature, the inversion procedure may overestimate sound-speed variations in regions with sharp gradients of the sound-speed profile.

  16. Verification of the helioseismology travel-time measurement technique and the inversion procedure for sound speed using artificial data

    International Nuclear Information System (INIS)

    Parchevsky, K. V.; Zhao, J.; Hartlep, T.; Kosovichev, A. G.

    2014-01-01

    We performed three-dimensional numerical simulations of the solar surface acoustic wave field for the quiet Sun and for three models with different localized sound-speed perturbations in the interior with deep, shallow, and two-layer structures. We used the simulated data generated by two solar acoustics codes that employ the same standard solar model as a background model, but utilize different integration techniques and different models of stochastic wave excitation. Acoustic travel times were measured using a time-distance helioseismology technique, and compared with predictions from ray theory frequently used for helioseismic travel-time inversions. It is found that the measured travel-time shifts agree well with the helioseismic theory for sound-speed perturbations, and for the measurement procedure with and without phase-speed filtering of the oscillation signals. This testing verifies the whole measuring-filtering-inversion procedure for static sound-speed anomalies with small amplitude inside the Sun outside regions of strong magnetic field. It is shown that the phase-speed filtering, frequently used to extract specific wave packets and improve the signal-to-noise ratio, does not introduce significant systematic errors. Results of the sound-speed inversion procedure show good agreement with the perturbation models in all cases. Due to its smoothing nature, the inversion procedure may overestimate sound-speed variations in regions with sharp gradients of the sound-speed profile.

  17. Generated forces and heat during the critical stages of friction stir welding and processing

    Energy Technology Data Exchange (ETDEWEB)

    Hussein, Sadiq Aziz; Tahir, Abd Salam Md; Izamshah, R. [University Teknikal Malaysia Melaka, Malacca (Malaysia)

    2015-10-15

    The solid-state behavior of friction stir welding process results in violent mechanical forces that should be mitigated, if not eliminated. Plunging and dwell time are the two critical stages of this welding process in terms of the generated forces and the related heat. In this study, several combinations of pre-decided penetration speeds, rotational speeds, tool designs, and dwell time periods were used to investigate these two critical stages. Moreover, a coupled-field thermal-structural finite element model was developed to validate the experimental results and the induced stresses. The experimental results revealed the relatively large changes in force and temperature during the first two stages compared with those during the translational tool movement stage. An important procedure to mitigate the undesired forces was then suggested. The model prediction of temperature values and their distribution were in good agreement with the experimental prediction. Therefore, the thermal history of this non-uniform heat distribution was used to estimate the induced thermal stresses. Despite the 37% increase in these stresses when 40 s dwell time was used instead of 5 s, these stresses showed no effect on the axial force values because of the soft material incidence and stir effects.

  18. Generated forces and heat during the critical stages of friction stir welding and processing

    International Nuclear Information System (INIS)

    Hussein, Sadiq Aziz; Tahir, Abd Salam Md; Izamshah, R.

    2015-01-01

    The solid-state behavior of friction stir welding process results in violent mechanical forces that should be mitigated, if not eliminated. Plunging and dwell time are the two critical stages of this welding process in terms of the generated forces and the related heat. In this study, several combinations of pre-decided penetration speeds, rotational speeds, tool designs, and dwell time periods were used to investigate these two critical stages. Moreover, a coupled-field thermal-structural finite element model was developed to validate the experimental results and the induced stresses. The experimental results revealed the relatively large changes in force and temperature during the first two stages compared with those during the translational tool movement stage. An important procedure to mitigate the undesired forces was then suggested. The model prediction of temperature values and their distribution were in good agreement with the experimental prediction. Therefore, the thermal history of this non-uniform heat distribution was used to estimate the induced thermal stresses. Despite the 37% increase in these stresses when 40 s dwell time was used instead of 5 s, these stresses showed no effect on the axial force values because of the soft material incidence and stir effects

  19. Space-time wind speed forecasting for improved power system dispatch

    KAUST Repository

    Zhu, Xinxin

    2014-02-27

    To support large-scale integration of wind power into electric energy systems, state-of-the-art wind speed forecasting methods should be able to provide accurate and adequate information to enable efficient, reliable, and cost-effective scheduling of wind power. Here, we incorporate space-time wind forecasts into electric power system scheduling. First, we propose a modified regime-switching, space-time wind speed forecasting model that allows the forecast regimes to vary with the dominant wind direction and with the seasons, hence avoiding a subjective choice of regimes. Then, results from the wind forecasts are incorporated into a power system economic dispatch model, the cost of which is used as a loss measure of the quality of the forecast models. This, in turn, leads to cost-effective scheduling of system-wide wind generation. Potential economic benefits arise from the system-wide generation of cost savings and from the ancillary service cost savings. We illustrate the economic benefits using a test system in the northwest region of the United States. Compared with persistence and autoregressive models, our model suggests that cost savings from integration of wind power could be on the scale of tens of millions of dollars annually in regions with high wind penetration, such as Texas and the Pacific northwest. © 2014 Sociedad de Estadística e Investigación Operativa.

  20. Towards real-time VMAT verification using a prototype, high-speed CMOS active pixel sensor.

    Science.gov (United States)

    Zin, Hafiz M; Harris, Emma J; Osmond, John P F; Allinson, Nigel M; Evans, Philip M

    2013-05-21

    This work investigates the feasibility of using a prototype complementary metal oxide semiconductor active pixel sensor (CMOS APS) for real-time verification of volumetric modulated arc therapy (VMAT) treatment. The prototype CMOS APS used region of interest read out on the chip to allow fast imaging of up to 403.6 frames per second (f/s). The sensor was made larger (5.4 cm × 5.4 cm) using recent advances in photolithographic technique but retains fast imaging speed with the sensor's regional read out. There is a paradigm shift in radiotherapy treatment verification with the advent of advanced treatment techniques such as VMAT. This work has demonstrated that the APS can track multi leaf collimator (MLC) leaves moving at 18 mm s(-1) with an automatic edge tracking algorithm at accuracy better than 1.0 mm even at the fastest imaging speed. Evaluation of the measured fluence distribution for an example VMAT delivery sampled at 50.4 f/s was shown to agree well with the planned fluence distribution, with an average gamma pass rate of 96% at 3%/3 mm. The MLC leaves motion and linac pulse rate variation delivered throughout the VMAT treatment can also be measured. The results demonstrate the potential of CMOS APS technology as a real-time radiotherapy dosimeter for delivery of complex treatments such as VMAT.

  1. The Effect of Premixed Al-Cu Powder on the Stir Zone in Friction Stir Welding of AA3003-H18

    Science.gov (United States)

    Abnar, B.; Kazeminezhad, M.; Kokabi, A. H.

    2015-02-01

    In this research, 3-mm-thick AA3003-H18 non-heat-treatable aluminum alloy plates were joined by friction stir welding (FSW). It was performed by adding pure Cu and premixed Cu-Al powders at various rotational speeds of 800, 1000, and 1200 rpm and constant traveling speeds of 100 mm/min. At first, the powder was filled into the gap (0.2 or 0.4 mm) between two aluminum alloy plates, and then the FSW process was performed in two passes. The microstructure, mechanical properties, and formation of intermetallic compounds were investigated in both cases of using pure Cu and premixed Al-Cu powders. The results of using pure Cu and premixed Al-Cu powders were compared in the stir zone at various rotational speeds. The copper particle distribution and formation of Al-Cu intermetallic compounds (Al2Cu and AlCu) in the stir zone were desirable using premixed Al-Cu powder into the gap. The hardness values were significantly increased by formation of Al-Cu intermetallic compounds in the stir zone and it was uniform throughout the stir zone when premixed Al-Cu powder was used. Also, longitudinal tensile strength from the stir zone was higher when premixed Al-Cu powder was used instead of pure Cu powder.

  2. continuous stirred tank reactor (CSTR)

    African Journals Online (AJOL)

    AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search ... stirred tank reactor (CSTR) and the small and large intestines as plug flow reactor (PFR) ... from the two equations are used for the reactor sizing of the modeled reactors.

  3. C18-coated stir bar sorptive extraction combined with high performance liquid chromatography-electrospray tandem mass spectrometry for the analysis of sulfonamides in milk and milk powder.

    Science.gov (United States)

    Yu, Chunhe; Hu, Bin

    2012-02-15

    A simple, rapid, sensitive, inexpensive and less sample consuming method of C(18)-stir bar sorptive extraction (SBSE)-high performance liquid chromatography (HPLC)-tandem mass spectrometry (MS/MS) was proposed for the determination of six sulfonamides in milk and milk powder samples. C(18) silica particles coated stir bar was prepared by adhesion method, and two kinds of adhesive glue, polydimethylsiloxane (PDMS) sol and epoxy glue were tried. It was found that the C(18)-coated stir bar prepared by PDMS sol as adhesive glue is more robust than that prepared by epoxy glue when liquid desorption was employed, in terms of both lifetime and organic solvent tolerance. The preparation of C(18) stir bar was simple with good mechanic strength and the stir bar could be reused for more than 20 times. Granular coating has relatively high specific surface area and is propitious to sorptive extraction based process. Compared to conventional PDMS SBSE coating, C(18) coating shows good affinity to the target polar/weak polar sulfonamides. To achieve optimum SBSE extraction performance, several parameters including extraction and desorption time, ionic strength, sample pH and stirring speed were investigated. The detection limits of the proposed method for six sulfonamides were in the range of 0.9-10.5 μg/L for milk and 2.7-31.5 μg/kg for milk powder. Good linearities were obtained for sulfonamides with the correlation coefficients (R) above 0.9922. Finally, the proposed method was successfully applied to the determination of sulfonamides in milk and milk powder samples and satisfied recoveries of spiked target compounds in real samples were obtained. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. High-speed charge-to-time converter ASIC for the Super-Kamiokande detector

    Energy Technology Data Exchange (ETDEWEB)

    Nishino, H., E-mail: nishino@post.kek.j [Institute for Cosmic Ray Research, University of Tokyo, Chiba 277-8582 (Japan); Awai, K.; Hayato, Y.; Nakayama, S.; Okumura, K.; Shiozawa, M.; Takeda, A. [Institute for Cosmic Ray Research, University of Tokyo, Chiba 277-8582 (Japan); Ishikawa, K.; Minegishi, A. [Iwatsu Test Instruments Corporation, Tokyo 168-8511 (Japan); Arai, Y. [The Institute of Particle and Nuclear Studies, KEK, Ibaraki 305-0801 (Japan)

    2009-11-11

    A new application-specific integrated circuit (ASIC), the high-speed charge-to-time converter (QTC) IWATSU CLC101, provides three channels, each consisting of preamplifier, discriminator, low-pass filter, and charge integration circuitry, optimized for the waveform of a photomultiplier tube (PMT). This ASIC detects PMT signals using individual built-in discriminators and drives output timing signals whose width represents the integrated charge of the PMT signal. Combined with external input circuits composed of passive elements, the QTC provides full analog signal processing for the detector's PMTs, ready for further processing by time-to-digital converters (TDCs). High-rate (>1MHz) signal processing is achieved by short-charge-conversion-time and baseline-restoration circuits. Wide-range charge measurements are enabled by offering three gain ranges while maintaining a short cycle time. QTC chip test results show good analog performance, with efficient detection for a single photoelectron signal, four orders of magnitude dynamic range (0.3mVapprox3V; 0.2approx2500pC), 1% charge linearity, 0.2 pC charge resolution, and 0.1 ns timing resolution. Test results on ambient temperature dependence, channel isolation, and rate dependence also meet specifications.

  5. High-speed charge-to-time converter ASIC for the Super-Kamiokande detector

    International Nuclear Information System (INIS)

    Nishino, H.; Awai, K.; Hayato, Y.; Nakayama, S.; Okumura, K.; Shiozawa, M.; Takeda, A.; Ishikawa, K.; Minegishi, A.; Arai, Y.

    2009-01-01

    A new application-specific integrated circuit (ASIC), the high-speed charge-to-time converter (QTC) IWATSU CLC101, provides three channels, each consisting of preamplifier, discriminator, low-pass filter, and charge integration circuitry, optimized for the waveform of a photomultiplier tube (PMT). This ASIC detects PMT signals using individual built-in discriminators and drives output timing signals whose width represents the integrated charge of the PMT signal. Combined with external input circuits composed of passive elements, the QTC provides full analog signal processing for the detector's PMTs, ready for further processing by time-to-digital converters (TDCs). High-rate (>1MHz) signal processing is achieved by short-charge-conversion-time and baseline-restoration circuits. Wide-range charge measurements are enabled by offering three gain ranges while maintaining a short cycle time. QTC chip test results show good analog performance, with efficient detection for a single photoelectron signal, four orders of magnitude dynamic range (0.3mV∼3V; 0.2∼2500pC), 1% charge linearity, 0.2 pC charge resolution, and 0.1 ns timing resolution. Test results on ambient temperature dependence, channel isolation, and rate dependence also meet specifications.

  6. A new wind speed forecasting strategy based on the chaotic time series modelling technique and the Apriori algorithm

    International Nuclear Information System (INIS)

    Guo, Zhenhai; Chi, Dezhong; Wu, Jie; Zhang, Wenyu

    2014-01-01

    Highlights: • Impact of meteorological factors on wind speed forecasting is taken into account. • Forecasted wind speed results are corrected by the associated rules. • Forecasting accuracy is improved by the new wind speed forecasting strategy. • Robust of the proposed model is validated by data sampled from different sites. - Abstract: Wind energy has been the fastest growing renewable energy resource in recent years. Because of the intermittent nature of wind, wind power is a fluctuating source of electrical energy. Therefore, to minimize the impact of wind power on the electrical grid, accurate and reliable wind power forecasting is mandatory. In this paper, a new wind speed forecasting approach based on based on the chaotic time series modelling technique and the Apriori algorithm has been developed. The new approach consists of four procedures: (I) Clustering by using the k-means clustering approach; (II) Employing the Apriori algorithm to discover the association rules; (III) Forecasting the wind speed according to the chaotic time series forecasting model; and (IV) Correcting the forecasted wind speed data using the associated rules discovered previously. This procedure has been verified by 31-day-ahead daily average wind speed forecasting case studies, which employed the wind speed and other meteorological data collected from four meteorological stations located in the Hexi Corridor area of China. The results of these case studies reveal that the chaotic forecasting model can efficiently improve the accuracy of the wind speed forecasting, and the Apriori algorithm can effectively discover the association rules between the wind speed and other meteorological factors. In addition, the correction results demonstrate that the association rules discovered by the Apriori algorithm have powerful capacities in handling the forecasted wind speed values correction when the forecasted values do not match the classification discovered by the association rules

  7. Integrated High-Speed Digital Optical True-Time-Delay Modules for Synthetic Aperture Radars, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Crystal Research, Inc. proposes an integrated high-speed digital optical true-time-delay module for advanced synthetic aperture radars. The unique feature of this...

  8. Optimization of mine ventilation fan speeds according to ventilation on demand and time of use tariff

    International Nuclear Information System (INIS)

    Chatterjee, Arnab; Zhang, Lijun; Xia, Xiaohua

    2015-01-01

    Highlights: • DSM techniques are applied to an underground mine ventilation network. • A minimization model is solved to find the optimal speeds of the main mine fan. • Ventilation on demand (VOD) leads to a saving of USD 213160. • The optimal mining schedule, together with VOD, leads to a saving of USD 277035. • According to a case study, a maximum of 2 540 035 kW h can be saved per year. - Abstract: In the current situation of the energy crisis, the mining industry has been identified as a promising area for application of demand side management (DSM) techniques. This paper investigates the potential for energy-cost savings and actual energy savings, by implementation of variable speed drives to ventilation fans in underground mines. In particular, ventilation on demand is considered in the study, i.e., air volume is adjusted according to the demand at varying times. Two DSM strategies, energy efficiency (EE) and load management (LM), are formulated and analysed. By modelling the network with the aid of Kirchhoff’s laws and Tellegen’s theorem, a nonlinear constrained minimization model is developed, with the objective of achieving EE. The model is also made to adhere to the fan laws, such that the fan power at its operating points is found to achieve realistic results. LM is achieved by finding the optimal starting time of the mining schedule, according to the time of use (TOU) tariff. A case study is shown to demonstrate the effects of the optimization model. The study suggests that by combining load shifting and energy efficiency techniques, an annual energy saving of 2 540 035 kW h is possible, leading to an annual cost saving of USD 277035

  9. Estimating the time evolution of NMR systems via a quantum-speed-limit-like expression

    Science.gov (United States)

    Villamizar, D. V.; Duzzioni, E. I.; Leal, A. C. S.; Auccaise, R.

    2018-05-01

    Finding the solutions of the equations that describe the dynamics of a given physical system is crucial in order to obtain important information about its evolution. However, by using estimation theory, it is possible to obtain, under certain limitations, some information on its dynamics. The quantum-speed-limit (QSL) theory was originally used to estimate the shortest time in which a Hamiltonian drives an initial state to a final one for a given fidelity. Using the QSL theory in a slightly different way, we are able to estimate the running time of a given quantum process. For that purpose, we impose the saturation of the Anandan-Aharonov bound in a rotating frame of reference where the state of the system travels slower than in the original frame (laboratory frame). Through this procedure it is possible to estimate the actual evolution time in the laboratory frame of reference with good accuracy when compared to previous methods. Our method is tested successfully to predict the time spent in the evolution of nuclear spins 1/2 and 3/2 in NMR systems. We find that the estimated time according to our method is better than previous approaches by up to four orders of magnitude. One disadvantage of our method is that we need to solve a number of transcendental equations, which increases with the system dimension and parameter discretization used to solve such equations numerically.

  10. Process techniques of charge transfer time reduction for high speed CMOS image sensors

    International Nuclear Information System (INIS)

    Cao Zhongxiang; Li Quanliang; Han Ye; Qin Qi; Feng Peng; Liu Liyuan; Wu Nanjian

    2014-01-01

    This paper proposes pixel process techniques to reduce the charge transfer time in high speed CMOS image sensors. These techniques increase the lateral conductivity of the photo-generated carriers in a pinned photodiode (PPD) and the voltage difference between the PPD and the floating diffusion (FD) node by controlling and optimizing the N doping concentration in the PPD and the threshold voltage of the reset transistor, respectively. The techniques shorten the charge transfer time from the PPD diode to the FD node effectively. The proposed process techniques do not need extra masks and do not cause harm to the fill factor. A sub array of 32 × 64 pixels was designed and implemented in the 0.18 μm CIS process with five implantation conditions splitting the N region in the PPD. The simulation and measured results demonstrate that the charge transfer time can be decreased by using the proposed techniques. Comparing the charge transfer time of the pixel with the different implantation conditions of the N region, the charge transfer time of 0.32 μs is achieved and 31% of image lag was reduced by using the proposed process techniques. (semiconductor devices)

  11. Numerical Simulation of Mechanical Property of Post Friction Stir Weld Artificial Ageing of Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    WAN Zhenyu

    2017-08-01

    Full Text Available KWN model was used to establish the precipitation evolution model of friction stir welding of Al-Mg-Si alloy. The yield strength was divided into three parts:the contribution from grain size, the contribution from solid solution and the contribution from the precipitations. Based on this model, the yield strength and hardness of friction stir weld was predicted. The effect of post weld artificial ageing on mechanical properties of friction stir weld was further investigated. The results indicate that longer holding time can be beneficial to the recovery of mechanical properties in the stirring zone. Higher temperature can lead to quick recovery of mechanical properties in the stirring zone, but when the holding temperature is higher than 200℃, longer holding time can lead the base metal softened, which is harmful to the service of friction stir welds. The mechanical property in the heat affected zone cannot be improved by post weld artificial ageing.

  12. The effect of centrifugation speed and time on pre-analytical platelet activation

    DEFF Research Database (Denmark)

    Söderström, Anna Cecilia; Nybo, Mads; Nielsen, Christian

    2016-01-01

    BACKGROUND: The results of laboratory analyses are affected by pre-analytical variables, and in particular can platelets be activated by shear handling stress and secrete granular substances. We therefore evaluated the effect of centrifugation speed and time on pre-analytical platelet activation....... METHODS: Citrate- and EDTA-anticoagulated blood from healthy volunteers were centrifuged at 80-10,000 g for 5-15 min to prepare plasma and platelet-rich plasma. Pre-analytical platelet activation was assessed by flow cytometric measurement of platelet P-selectin (CD62p) expression. Blood cell counts, mean...... of platelets expressing P-selectin in citrate- and EDTA-plasma centrifuged at 2000 g for 10 min were 43% [interquartile range (IQR), 38%-53%] and 56% (IQR, 31%-78%), respectively (p=0.82). Platelet-rich plasma prepared at 100-250 g for 10 min had significantly lower platelet P-selectin expression (11%-15%), p...

  13. Nature of complex time eigenvalues of the one speed transport equation in a homogeneous sphere

    International Nuclear Information System (INIS)

    Dahl, E.B.; Sahni, D.C.

    1990-01-01

    The complex time eigenvalues of the transport equation have been studied for one speed neutrons, scattered isotropically in a homogeneous sphere with vacuum boundary conditions. It is shown that the complex decay constants vary continuously with the radius of the sphere. Our earlier conjecture (Dahl and Sahni (1983-84)) regarding disjoint arcs is thus shown to be true. We also indicate that complex decay constants exist even for large assemblies, though with rapid oscillations in the corresponding eigenvectors. These modes cannot be predicted by the diffusion equation as this behaviour of the eigenvectors contradicts the assumption of 'slowly varying flux' needed to derive the diffusion approximation from the transport equation. For an infinite system, the existence of complex modes is related to the solution of a homogeneous equation. (author)

  14. Race Factors Affecting Performance Times in Elite Long-Track Speed Skating.

    Science.gov (United States)

    Noordhof, Dionne A; Mulder, Roy C; de Koning, Jos J; Hopkins, Will G

    2016-05-01

    Analysis of sport performance can provide effects of environmental and other venue-specific factors in addition to estimates of within-athlete variability between competitions, which determines smallest worthwhile effects. To analyze elite long-track speed-skating events. Log-transformed performance times were analyzed with a mixed linear model that estimated percentage mean effects for altitude, barometric pressure, type of rink, and competition importance. In addition, coefficients of variation representing residual venue-related differences and within-athlete variability between races within clusters spanning ~8 d were determined. Effects and variability were assessed with magnitude-based inference. A 1000-m increase in altitude resulted in very large mean performance improvements of 2.8% in juniors and 2.1% in seniors. An increase in barometric pressure of 100 hPa resulted in a moderate reduction in performance of 1.1% for juniors but an unclear effect for seniors. Only juniors competed at open rinks, resulting in a very large reduction in performance of 3.4%. Juniors and seniors showed small performance improvements (0.4% and 0.3%) at the more important competitions. After accounting for these effects, residual venue-related variability was still moderate to large. The within-athlete within-cluster race-to-race variability was 0.3-1.3%, with a small difference in variability between male (0.8%) and female juniors (1.0%) and no difference between male and female seniors (both 0.6%). The variability in performance times of skaters is similar to that of athletes in other sports in which air or water resistance limits speed. A performance enhancement of 0.1-0.4% by top-10 athletes is necessary to increase medal-winning chances by 10%.

  15. Application of Taguchi approach to optimize friction stir welding parameters of polyethylene

    Directory of Open Access Journals (Sweden)

    Bejaoui S.

    2010-06-01

    Full Text Available This paper presents experimental and numerical results of butt friction stir welding of high density polyethylene. The FSW designed tool insulates the welded samples and preserves the heat gained from friction thus avoiding the appearance of blisters and splits after welding. The experimental tests, conducted according to combinations of process factors such as rotation speed, welding speed, pin diameter and hold time at beginning welding, were carried out according the Taguchi orthogonal table L27 in randomized way. Temperatures in the joint during the welding operation and flow stresses from the tensile tests of welded samples were measured and variances were analyzed. Identified models were used to simulate, by finite elements, the tensile tests performed on specimens having a weld cordon in their active area. The results show coherence between the numerical predictions and experimental observations in different cases of weld cordon mechanical behaviour.

  16. An improved hollow fiber solvent-stir bar microextraction for the preconcentration of anabolic steroids in biological matrix with determination by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Liu, Wei; Zhang, Lan; Fan, Liangbiao; Lin, Zian; Cai, Yimin; Wei, Zhenyi; Chen, Guonan

    2012-04-13

    In this paper, a convenient and self-assembled hollow fiber solvent-stir bar microextraction (HF-SSBME) device was developed, which could stir by itself. In the extraction process, the proposed device made the solvent "bar" not floating at the sample solution and exposing to air while organic solvents outside hollow fiber always wrapped with donor phase solvent, which reduced the vaporization of organic solvents. This design could improve the precisions and recoveries of experiments. For evaluating the device, seven anabolic steroids (prasterone, 5α-androstane-3α, 17β-diol, methandriol, 19-norandrostenediol, androstenediol, methyltestosterone and methandienone) were used as model analytes and extraction conditions such as type and volume of organic solvents, agitation speed, extraction time, extraction temperature and salt addition were studied in detail. Under the optimum conditions (15 μL toluene, 40 °C, stirring at 750 rpm for 30 min with 1.5 g sodium chloride addition in 20.0 mL donor phase), the linear ranges of anabolic steroids were 0.25-200 ng mL(-1) with gas chromatography-mass spectrometry. The limits of detection were lower than 0.10 ng mL(-1). The recoveries and precisions in spiked urine and hair samples were between 73.97-93.56% and 2.18-4.47% (n=5). HF-SSBME method combined the intrinsical merits of hollow fiber with the superiority of the proposed self-stirring device which can be developed to two-phase, three-phase and in situ derivatization modes with wide prospect of application. Besides, the pedestal of this proposed device can be converted to fix stir bar in stir bar sorptive extraction (SBSE) method. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Influence of time scale wind speed data on sustainability analysis for irrigating greenhouse crops

    Science.gov (United States)

    Díaz Méndez, Rodrigo; García Llaneza, Joaquín; Peillón, Manuel; Perdigones, Alicia; Sanchez, Raul; Tarquis, Ana M.; Garcia, Jose Luis

    2014-05-01

    Appropriate water supply at crop/farm level, with suitable costs, is becoming more and more important. Energy management is closely related to water supply in this context, being wind energy one of the options to be considered, using wind pumps for irrigation water supply. Therefore, it is important to characterize the wind speed frequency distribution to study the technical feasibility to use its energy for irrigation management purpose. The general objective of this present research is to analyze the impact of time scale recorded wind speed data in the sustainability for tomato (Solanum lycopersicum L.) grown under greenhouse at Cuban conditions using drip irrigation system. For this porpoise, a daily estimation balance between water needs and water availability was used to evaluate the feasibility of the most economic windmill irrigation system. Several factors were included: wind velocity (W, m/s) in function of the time scale averaged, flow supplied by the wind pump as a function of the elevation height (H, m) and daily greenhouse evapotranspiration. Monthly volumes of water required for irrigation (Dr, m3/ha) and in the water tank (Vd, m3), as well as the monthly irrigable area (Ar, ha), were estimated by cumulative deficit water budgeting taking in account these factors. Three-hourly wind velocity (W3h, m/s) data from 1992 till 2008 was available for this study. The original data was grouped in six and twelve hourly data (W6h and W12h respectively) as well as daily data (W24h). For each time scale the daily estimation balance was applied. A comparison of the results points out a need for at least three-hourly data to be used mainly in the months in which mean wind speed are close or below the pumps threshold speed to start-up functioning. References Manuel Esteban Peillon Mesa, Ana Maria Tarquis Alfonso, José Luis García Fernández, and Raúl Sánchez Calvo. The use of wind pumps for irrigating greenhouse tomato crops: a case study in Cuba. Geophysical

  18. Determining the Time of Flight and Speed of Sound on Different types of Edible Oil

    Science.gov (United States)

    Azman, N. A.; Hamid, S. B. Abd

    2017-11-01

    Edible oil is most often plant-based oils that have been extracted from various seeds. There are cases where the fully virgin edible oil was found to be a fraud. The adulterated edible oil indicates the intentional, fraudulent addition of extraneous, improper or cheaper ingredients puts into the oil or the dilution or removal of some valuable ingredient of the oil in order to increase profits. Hence, decrease the reliability of the Malaysian food product quality. This research was done by using the method of time of flight obtained using the Texas Instrument board, TDC1000-TDC7200 EVM connected to an ultrasonic transducer with 1 MHz frequency. The authors measured the time of flight and temperatures controlled from 20°C to 40°C of five vegetable oils (olive oil, sunflower oil, corn oil, coconut oil, and mustard oil). The value is observed and compared with other research from the literature review. From the study, time of flight values decreases exponentially while speed of sound value increases. This relationship will be useful in spectrum unfolding method to investigate the adulteration in different type of edible oil.This research outcome is to investigate the quality value of the different type of edible oil while eliminates the issues where the quality of Malaysian food product is not reliable.

  19. Non-contact Real-time heart rate measurements based on high speed circuit technology research

    Science.gov (United States)

    Wu, Jizhe; Liu, Xiaohua; Kong, Lingqin; Shi, Cong; Liu, Ming; Hui, Mei; Dong, Liquan; Zhao, Yuejin

    2015-08-01

    In recent years, morbidity and mortality of the cardiovascular or cerebrovascular disease, which threaten human health greatly, increased year by year. Heart rate is an important index of these diseases. To address this status, the paper puts forward a kind of simple structure, easy operation, suitable for large populations of daily monitoring non-contact heart rate measurement. In the method we use imaging equipment video sensitive areas. The changes of light intensity reflected through the image grayscale average. The light change is caused by changes in blood volume. We video the people face which include the sensitive areas (ROI), and use high-speed processing circuit to save the video as AVI format into memory. After processing the whole video of a period of time, we draw curve of each color channel with frame number as horizontal axis. Then get heart rate from the curve. We use independent component analysis (ICA) to restrain noise of sports interference, realized the accurate extraction of heart rate signal under the motion state. We design an algorithm, based on high-speed processing circuit, for face recognition and tracking to automatically get face region. We do grayscale average processing to the recognized image, get RGB three grayscale curves, and extract a clearer pulse wave curves through independent component analysis, and then we get the heart rate under the motion state. At last, by means of compare our system with Fingertip Pulse Oximeter, result show the system can realize a more accurate measurement, the error is less than 3 pats per minute.

  20. The Time Course of Knee Swelling Post Total Knee Arthroplasty and Its Associations with Quadriceps Strength and Gait Speed.

    Science.gov (United States)

    Pua, Yong-Hao

    2015-07-01

    This study examines the time course of knee swelling post total knee arthroplasty (TKA) and its associations with quadriceps strength and gait speed. Eighty-five patients with unilateral TKA participated. Preoperatively and on post-operative days (PODs) 1, 4, 14, and 90, knee swelling was measured using bioimpedance spectrometry. Preoperatively and on PODs 14 and 90, quadriceps strength was measured using isokinetic dynamometry while fast gait speed was measured using the timed 10-meter walk. On POD1, knee swelling increased ~35% from preoperative levels after which, knee swelling reduced but remained at ~11% above preoperative levels on POD90. In longitudinal, multivariable analyses, knee swelling was associated with quadriceps weakness (P<0.01) and slower gait speed (P=0.03). Interventions to reduce post-TKA knee swelling may be indicated to improve quadriceps strength and gait speed. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Effect of tool shape and welding parameters on mechanical properties and microstructure of dissimilar friction stir welded aluminium alloys

    OpenAIRE

    Chetan Aneja; Amit Handa

    2016-01-01

    In the present experimental study, dissimilar aluminum alloy AA5083 and AA6082 were friction stir welded by varying tool shape, welding speed and rotary speed of the tool in order to investigate the effect of varying tool shape and welding parameters on the mechanical properties as well as microstructure. The friction stir welding (FSW) process parameters have great influence on heat input per unit length of weld. The outcomes of experimental study prove that mechanical properties increases w...

  2.  Running speed during training and percent body fat predict race time in recreational male marathoners

    Directory of Open Access Journals (Sweden)

    Barandun U

    2012-07-01

    Full Text Available  Background: Recent studies have shown that personal best marathon time is a strong predictor of race time in male ultramarathoners. We aimed to determine variables predictive of marathon race time in recreational male marathoners by using the same characteristics of anthropometry and training as used for ultramarathoners.Methods: Anthropometric and training characteristics of 126 recreational male marathoners were bivariately and multivariately related to marathon race times.Results: After multivariate regression, running speed of the training units (β=-0.52, P<0.0001 and percent body fat (β=0.27, P <0.0001 were the two variables most strongly correlated with marathon race times. Marathon race time for recreational male runners may be estimated to some extent by using the following equation (r2 = 0.44: race time (minutes = 326.3 + 2.394 × (percent body fat, % – 12.06 × (speed in training, km/hours. Running speed during training sessions correlated with prerace percent body fat (r=0.33, P=0.0002. The model including anthropometric and training variables explained 44% of the variance of marathon race times, whereas running speed during training sessions alone explained 40%. Thus, training speed was more predictive of marathon performance times than anthropometric characteristics.Conclusion: The present results suggest that low body fat and running speed during training close to race pace (about 11 km/hour are two key factors for a fast marathon race time in recreational male marathoner runners.Keywords: body fat, skinfold thickness, anthropometry, endurance, athlete

  3. Real-Time, Interactive Echocardiography Over High-Speed Networks: Feasibility and Functional Requirements

    Science.gov (United States)

    Bobinsky, Eric A.

    1998-01-01

    Real-time, Interactive Echocardiography Over High Speed Networks: Feasibility and Functional Requirements is an experiment in advanced telemedicine being conducted jointly by the NASA Lewis Research Center, the NASA Ames Research Center, and the Cleveland Clinic Foundation. In this project, a patient undergoes an echocardiographic examination in Cleveland while being diagnosed remotely by a cardiologist in California viewing a real-time display of echocardiographic video images transmitted over the broadband NASA Research and Education Network (NREN). The remote cardiologist interactively guides the sonographer administering the procedure through a two-way voice link between the two sites. Echocardiography is a noninvasive medical technique that applies ultrasound imaging to the heart, providing a "motion picture" of the heart in action. Normally, echocardiographic examinations are performed by a sonographer and cardiologist who are located in the same medical facility as the patient. The goal of telemedicine is to allow medical specialists to examine patients located elsewhere, typically in remote or medically underserved geographic areas. For example, a small, rural clinic might have access to an echocardiograph machine but not a cardiologist. By connecting this clinic to a major metropolitan medical facility through a communications network, a minimally trained technician would be able to carry out the procedure under the supervision and guidance of a qualified cardiologist.

  4. Non Linear, Time Variant Speed Control of a Single Phase Hybrid Switched Reluctance Motor

    DEFF Research Database (Denmark)

    Jakobsen, Uffe; Ahn, Jin Woo

    2009-01-01

    A high torque ripple in a given motor always presents a challenge for the speed control, since this ripple may lead to excessive actuation and ultimately may even lead to instability. The conventional solution is to low pass filter the measured speed, but this lowers dynamic control performance...

  5. Running Speed Can Be Predicted from Foot Contact Time during Outdoor over Ground Running

    NARCIS (Netherlands)

    de Ruiter, C.J.; van Oeveren, B.; Francke, A.; Zijlstra, P.; van Dieen, J.H.

    2016-01-01

    The number of validation studies of commercially available foot pods that provide estimates of running speed is limited and these studies have been conducted under laboratory conditions. Moreover, internal data handling and algorithms used to derive speed from these pods are proprietary and thereby

  6. Optimizing friction stir weld parameters of aluminum and copper using conventional milling machine

    Science.gov (United States)

    Manisegaran, Lohappriya V.; Ahmad, Nurainaa Ayuni; Nazri, Nurnadhirah; Noor, Amirul Syafiq Mohd; Ramachandran, Vignesh; Ismail, Muhammad Tarmizizulfika; Ahmad, Ku Zarina Ku; Daruis, Dian Darina Indah

    2018-05-01

    The joining of two of any particular materials through friction stir welding (FSW) are done by a rotating tool and the work piece material that generates heat which causes the region near the FSW tool to soften. This in return will mechanically intermix the work pieces. The first objective of this study is to join aluminum plates and copper plates by means of friction stir welding process using self-fabricated tools and conventional milling machine. This study also aims to investigate the optimum process parameters to produce the optimum mechanical properties of the welding joints for Aluminum plates and Copper plates. A suitable tool bit and a fixture is to be fabricated for the welding process. A conventional milling machine will be used to weld the aluminum and copper. The most important parameters to enable the process are speed and pressure of the tool (or tool design and alignment of the tool onto the work piece). The study showed that the best surface finish was produced from speed of 1150 rpm and tool bit tilted to 3°. For a 200mm × 100mm Aluminum 6061 with plate thickness of 2 mm at a speed of 1 mm/s, the time taken to complete the welding is only 200 seconds or equivalent to 3 minutes and 20 seconds. The Copper plates was successfully welded using FSW with tool rotation speed of 500 rpm, 700 rpm, 900 rpm, 1150 rpm and 1440 rpm and with welding traverse rate of 30 mm/min, 60 mm/min and 90 mm/min. As the conclusion, FSW using milling machine can be done on both Aluminum and Copper plates, however the weld parameters are different for the two types of plates.

  7. Integrating stochastic time-dependent travel speed in solution methods for the dynamic dial-a-ride problem.

    Science.gov (United States)

    Schilde, M; Doerner, K F; Hartl, R F

    2014-10-01

    In urban areas, logistic transportation operations often run into problems because travel speeds change, depending on the current traffic situation. If not accounted for, time-dependent and stochastic travel speeds frequently lead to missed time windows and thus poorer service. Especially in the case of passenger transportation, it often leads to excessive passenger ride times as well. Therefore, time-dependent and stochastic influences on travel speeds are relevant for finding feasible and reliable solutions. This study considers the effect of exploiting statistical information available about historical accidents, using stochastic solution approaches for the dynamic dial-a-ride problem (dynamic DARP). The authors propose two pairs of metaheuristic solution approaches, each consisting of a deterministic method (average time-dependent travel speeds for planning) and its corresponding stochastic version (exploiting stochastic information while planning). The results, using test instances with up to 762 requests based on a real-world road network, show that in certain conditions, exploiting stochastic information about travel speeds leads to significant improvements over deterministic approaches.

  8. Mixing In Jet-Stirred Reactors With Different Geometries

    KAUST Repository

    Ayass, Wassim W.

    2013-12-01

    This work offers a well-developed understanding of the mixing process inside Jet- Stirred Reactors (JSR’s) with different geometries. Due to the difficulty of manufacturing these JSR’s made in quartz, existing JSR configurations were assessed with certain modifications and optimal operating conditions were suggested for each reactor. The effect of changing the reactor volume, the nozzle diameter and shape on mixing were both studied. Two nozzle geometries were examined in this study, a crossed shape nozzle and an inclined shape nozzle. Overall, six reactor configurations were assessed by conducting tracer experiments - using the state-of-art technologies of high-speed cameras and laser absorption spectroscopy- and Computational Fluid Dynamics (CFD) simulations. The high-speed camera tracer experiment gives unique qualitative information – not present in the literature – about the actual flow field. On the other hand, when using the laser technique, a more quantitative analysis emerges with determining the experimental residence time distribution (RTD) curves of each reactor. Comparing these RTD curves with the ideal curve helped in eliminating two cases. Finally, the CFD simulations predict the RTD curves as well as the mixing levels of the JSR’s operated at different residence times. All of these performed studies suggested the use of an inclined nozzle configuration with a reactor diameter D of 40mm and a nozzle diameter d of 1mm as the optimal choice for low residence time operation. However, for higher residence times, the crossed configuration reactor with D=56mm and d=0.3mm gave a nearly perfect behavior.

  9. Implementation of PID Controller in MATLAB for Real Time DC Motor Speed Control System

    Directory of Open Access Journals (Sweden)

    Manjunatha Reddy H. K.

    2011-03-01

    Full Text Available In this paper the implementation of PIDC (proportional + integral + derivative controller in MATLAB environment for real time DC motor speed control is presented. The MATLAB environment is chosen because of availability of tool boxes which allows the effective way of implementation and analysis of the control system. The performance of PID controller for different inputs is studied. To establish a communication between PC and process parameter, an indigenous Analog to digital and digital to analog (AD-DA board is designed. This board consists of 12-bit A/D converter and 12-bit D/A converter to facilitate the data acquisition and control. In the present study Advantech make PCI-1751 DIOT card is used to interface AD-DA board to PC externally. The data between the AD-DA board and the PC is communicated through the script file written in MATLAB environment. By applying different standard test commands such as step, square, staircase and triangular, the performance of PID controller is studied. The PID controller provides better system response in terms of transient as well as steady-state performances. The controller parameters are manually tuned (kp=0.232, ki=0.078 and kd=0.035 and the results of the best tuned PID controller are presented.

  10. Time response analysis in suspension system design of a high-speed car

    Science.gov (United States)

    Pagwiwoko, Cosmas Pandit

    2010-03-01

    A land speed record vehicle is designed to run on a flat surface like salt lake where the wheels are normally made from solid metal with a special suspension system. The suspension is designed to provide a stable platform to keep the wheel treads on tract, to insulate the car and the driver from the surface irregularities and to take part of good handling properties. The surface condition of the lake beds is basically flat without undulations but with inconsistent surface textures and ridges. Spring with nonlinear rate is used with the reason that the resistance builds up roughly proportional to the aerodynamic download for keeping the height more nearly constant. The objective of the work is to produce an efficient method for assisting the design of suspension system. At the initial step, the stiffness and the damping constants are determined based on RMS optimization by following the optimization strategy i.e. to minimize the absolute acceleration respect to the relative displacement of the suspension. Power bond graph technique is then used to model the nonlinearity of the components i.e. spring and dashpot of the suspension system. This technique also enables to incorporate the interactions of dynamic response of the vehicle's body with aerodynamic flow as a result of the base excitation of the ground to the wheels. The simulation is conducted on the platform of Simulink-MATLAB and the interactions amongst the components within the system are observed in time domain to evaluate the effectiveness of the suspension.

  11. Usability of a new multiple high-speed pulse time data registration, processing and real-time display system for pulse time interval analysis

    International Nuclear Information System (INIS)

    Yawata, Takashi; Sakaue, Hisanobu; Hashimoto, Tetsuo; Itou, Shigeki

    2006-01-01

    A new high-speed multiple pulse time data registration, processing and real-time display system for time interval analysis (TIA) was developed for counting either β-α or α-α correlated decay-events. The TIA method has been so far limited to selective extraction of successive α-α decay events within the milli-second time scale owing to the use of original electronic hardware. In the present pulse-processing system, three different high-speed α/β(γ) pulses could be fed quickly to original 32 bit PCI board (ZN-HTS2) within 1 μs. This original PCI board is consisting of a timing-control IC (HTS-A) and 28 bit counting IC (HTS-B). All channel and pulse time data were stored to FIFO RAM, followed to transfer into temporary CPU RAM (32 MB) by DMA. Both data registration (into main RAM (200 MB)) and calculation of pulse time intervals together with real-time TIA-distribution display simultaneously processed using two sophisticate softwares. The present system has proven to succeed for the real-time display of TIA distribution spectrum even when 1.6x10 5 cps pulses from pulse generator were given to the system. By using this new system combined with liquid scintillation counting (LSC) apparatus, both a natural micro-second order β-α correlated decay-events and a milli-second order α-α correlated decay-event could be selectively extracted from the mixture of natural radionuclides. (author)

  12. Calibration and performance of a stirred benthic chamber

    Science.gov (United States)

    Buchholtz-ten Brink, M. R.; Gust, G.; Chavis, D.

    1989-07-01

    The physical and chemical boundary layer parameters characteristic for a benthic chamber were cross-calibrated by the use of two methods in the laboratory: (1) flush-mounted hot-film sensors, which measure the friction velocity u ∗, and (2) the alabaster dissolution technique, which measures the equivalent film thickness z. Tests of five stirring devices were made, using both techniques, to improve the stirring mechanism in the MANOP Lander flux chambers. The stirring device that was finally implemented consisted of four rods and produced spatially averaged friction velocities u ∗ ranging from 0.1 to 0.5 cm s -1 (i.e. mean film thickness z from 500 to 180 μm) when running at speeds from 3 to 9 rpm. The friction velocity field at the sediment surface is related to the rpm of the stirring device and the penetration depth of the chamber into the sediments; combinations of both can create z and u ∗ inside the chamber that duplicate those of many natural environments. The log-log calibration relationship found between u ∗ and transfer coefficients K' also provides a means to predict the mass-transfer resistance of solutes at the sediment-water interface from measurements of mean bottom stress.

  13. Walking, running, and resting under time, distance, and average speed constraints: optimality of walk–run–rest mixtures

    Science.gov (United States)

    Long, Leroy L.; Srinivasan, Manoj

    2013-01-01

    On a treadmill, humans switch from walking to running beyond a characteristic transition speed. Here, we study human choice between walking and running in a more ecological (non-treadmill) setting. We asked subjects to travel a given distance overground in a given allowed time duration. During this task, the subjects carried, and could look at, a stopwatch that counted down to zero. As expected, if the total time available were large, humans walk the whole distance. If the time available were small, humans mostly run. For an intermediate total time, humans often use a mixture of walking at a slow speed and running at a higher speed. With analytical and computational optimization, we show that using a walk–run mixture at intermediate speeds and a walk–rest mixture at the lowest average speeds is predicted by metabolic energy minimization, even with costs for transients—a consequence of non-convex energy curves. Thus, sometimes, steady locomotion may not be energy optimal, and not preferred, even in the absence of fatigue. Assuming similar non-convex energy curves, we conjecture that similar walk–run mixtures may be energetically beneficial to children following a parent and animals on long leashes. Humans and other animals might also benefit energetically from alternating between moving forward and standing still on a slow and sufficiently long treadmill. PMID:23365192

  14. Walking, running, and resting under time, distance, and average speed constraints: optimality of walk-run-rest mixtures.

    Science.gov (United States)

    Long, Leroy L; Srinivasan, Manoj

    2013-04-06

    On a treadmill, humans switch from walking to running beyond a characteristic transition speed. Here, we study human choice between walking and running in a more ecological (non-treadmill) setting. We asked subjects to travel a given distance overground in a given allowed time duration. During this task, the subjects carried, and could look at, a stopwatch that counted down to zero. As expected, if the total time available were large, humans walk the whole distance. If the time available were small, humans mostly run. For an intermediate total time, humans often use a mixture of walking at a slow speed and running at a higher speed. With analytical and computational optimization, we show that using a walk-run mixture at intermediate speeds and a walk-rest mixture at the lowest average speeds is predicted by metabolic energy minimization, even with costs for transients-a consequence of non-convex energy curves. Thus, sometimes, steady locomotion may not be energy optimal, and not preferred, even in the absence of fatigue. Assuming similar non-convex energy curves, we conjecture that similar walk-run mixtures may be energetically beneficial to children following a parent and animals on long leashes. Humans and other animals might also benefit energetically from alternating between moving forward and standing still on a slow and sufficiently long treadmill.

  15. Modelling of baffled stirred tanks

    Energy Technology Data Exchange (ETDEWEB)

    Ahlstedt, H.; Lahtinen, M. [Tampere Univ. of Technology (Finland). Energy and Process Engineering

    1996-12-31

    The three-dimensional flow field of a baffled stirred tank has been calculated using four different turbulence models. The tank is driven by a Rushton-type impeller. The boundary condition for the impeller region has been given as a source term or by calculating the impeller using the sliding mesh technique. Calculated values have been compared with measured data. (author)

  16. Modelling of baffled stirred tanks

    Energy Technology Data Exchange (ETDEWEB)

    Ahlstedt, H; Lahtinen, M [Tampere Univ. of Technology (Finland). Energy and Process Engineering

    1997-12-31

    The three-dimensional flow field of a baffled stirred tank has been calculated using four different turbulence models. The tank is driven by a Rushton-type impeller. The boundary condition for the impeller region has been given as a source term or by calculating the impeller using the sliding mesh technique. Calculated values have been compared with measured data. (author)

  17. Deformation During Friction Stir Welding

    Science.gov (United States)

    White, Henry J.

    2002-01-01

    Friction Stir Welding (FSW) is a solid state welding process that exhibits characteristics similar to traditional metal cutting processes. The plastic deformation that occurs during friction stir welding is due to the superposition of three flow fields: a primary rotation of a radially symmetric solid plug of metal surrounding the pin tool, a secondary uniform translation, and a tertiary ring vortex flow (smoke rings) surrounding the tool. If the metal sticks to the tool, the plug surface extends down into the metal from the outer edge of the tool shoulder, decreases in diameter like a funnel, and closes up beneath the pin. Since its invention, ten years have gone by and still very little is known about the physics of the friction stir welding process. In this experiment, an H13 steel weld tool (shoulder diameter, 0.797 in; pin diameter, 0.312 in; and pin length, 0.2506 in) was used to weld three 0.255 in thick plates. The deformation behavior during friction stir welding was investigated by metallographically preparing a plan view sections of the weldment and taking Vickers hardness test in the key-hole region.

  18. Biomechanical characteristics of skeletal muscles and associations between running speed and contraction time in 8- to 13-year-old children.

    Science.gov (United States)

    Završnik, Jernej; Pišot, Rado; Šimunič, Boštjan; Kokol, Peter; Blažun Vošner, Helena

    2017-02-01

    Objective To investigate associations between running speeds and contraction times in 8- to 13-year-old children. Method This longitudinal study analyzed tensiomyographic measurements of vastus lateralis and biceps femoris muscles' contraction times and maximum running speeds in 107 children (53 boys, 54 girls). Data were evaluated using multiple correspondence analysis. Results A gender difference existed between the vastus lateralis contraction times and running speeds. The running speed was less dependent on vastus lateralis contraction times in boys than in girls. Analysis of biceps femoris contraction times and running speeds revealed that running speeds of boys were much more structurally associated with contraction times than those of girls, for whom the association seemed chaotic. Conclusion Joint category plots showed that contraction times of biceps femoris were associated much more closely with running speed than those of the vastus lateralis muscle. These results provide insight into a new dimension of children's development.

  19. Production of Newcastle Disease Virus by Vero Cells Grown on Cytodex 1 Microcarriers in a 2-Litre Stirred Tank Bioreactor

    Directory of Open Access Journals (Sweden)

    Mohd Azmir Arifin

    2010-01-01

    Full Text Available The aim of this study is to prepare a model for the production of Newcastle disease virus (NDV lentogenic F strain using cell culture in bioreactor for live attenuated vaccine preparation. In this study, firstly we investigated the growth of Vero cells in several culture media. The maximum cell number was yielded by culture of Vero cells in Dulbecco's Modified Eagle Medium (DMEM which was 1.93×106 cells/ml. Secondly Vero cells were grown in two-litre stirred tank bioreactor by using several commercial microcarriers. We achieved the maximum cell concentration about 7.95×105 cells/ml when using Cytodex 1. Later we produced Newcastle Disease virus in stirred tank bioreactor based on the design developed using Taguchi L4 method. Results reveal that higher multiplicity of infection (MOI and size of cell inoculums can yield higher virus titer. Finally, virus samples were purified using high-speed centrifugation based on 3∗∗(3-1 Fractional Factorial Design. Statistical analysis showed that the maximum virus titer can be achieved at virus sample concentration of 58.45% (v/v, centrifugation speed of 13729 rpm, and centrifugation time of 4 hours. As a conclusion, high yield of virus titer could be achieved through optimization of cell culture in bioreactor and separation by high-speed centrifugation.

  20. Temperature-Controlled High-Speed AFM: Real-Time Observation of Ripple Phase Transitions.

    Science.gov (United States)

    Takahashi, Hirohide; Miyagi, Atsushi; Redondo-Morata, Lorena; Scheuring, Simon

    2016-11-01

    With nanometer lateral and Angstrom vertical resolution, atomic force microscopy (AFM) has contributed unique data improving the understanding of lipid bilayers. Lipid bilayers are found in several different temperature-dependent states, termed phases; the main phases are solid and fluid phases. The transition temperature between solid and fluid phases is lipid composition specific. Under certain conditions some lipid bilayers adopt a so-called ripple phase, a structure where solid and fluid phase domains alternate with constant periodicity. Because of its narrow regime of existence and heterogeneity ripple phase and its transition dynamics remain poorly understood. Here, a temperature control device to high-speed atomic force microscopy (HS-AFM) to observe dynamics of phase transition from ripple phase to fluid phase reversibly in real time is developed and integrated. Based on HS-AFM imaging, the phase transition processes from ripple phase to fluid phase and from ripple phase to metastable ripple phase to fluid phase could be reversibly, phenomenologically, and quantitatively studied. The results here show phase transition hysteresis in fast cooling and heating processes, while both melting and condensation occur at 24.15 °C in quasi-steady state situation. A second metastable ripple phase with larger periodicity is formed at the ripple phase to fluid phase transition when the buffer contains Ca 2+ . The presented temperature-controlled HS-AFM is a new unique experimental system to observe dynamics of temperature-sensitive processes at the nanoscopic level. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Designing Sustainable Public Transportation: Integrated Optimization of Bus Speed and Holding Time in a Connected Vehicle Environment

    Directory of Open Access Journals (Sweden)

    Wei Wu

    2016-11-01

    Full Text Available Developing public transportation and giving priority to buses is a feasible solution for improving the level of public transportation service, which facilitates congestion alleviation and prevention, and contributes to urban development and city sustainability. This paper presents a novel bus operation control strategy including both holding control and speed control to improve the level of service of transit systems within a connected vehicle environment. Most previous work focuses on optimization of signal timing to decrease the bus signal delay by assuming that holding control is not applied; the speed of buses is given as a constant input and the acceleration and deceleration processes of buses can be neglected. This paper explores the benefits of a bus operation control strategy to minimize the total cost, which includes bus signal delay, bus holding delay, bus travel delay, acceleration cost due to frequent stops and intense driving. A set of formulations are developed to explicitly capture the interaction between bus holding control and speed control. Experimental analysisand simulation tests have shown that the proposed integrated operational model outperforms the traditional control, speed control only, or holding control only strategies in terms of reducing the total cost of buses. The sensitivity analysis has further demonstrated the potential effectiveness of the proposed approach to be applied in a real-time bus operation control system under different levels of traffic demand, bus stop locations, and speed limits.

  2. Impact of Magnetic Stirring on Stainless Steel Integrity: Effect on Biopharmaceutical Processing.

    Science.gov (United States)

    Thompson, Christopher; Wilson, Kelly; Kim, Yoen Joo; Xie, Min; Wang, William K; Wendeler, Michaela

    2017-11-01

    Stainless steel containers are widely used in the pharmaceutical and biopharmaceutical industry for the storage of buffers, process intermediates, and purified drug substance. They are generally held to be corrosion resistant, biocompatible, and nonreactive, although it is well established that trace amounts of metal ions can leach from stainless steel equipment into biopharmaceutical products. We report here that the use of stainless steel containers in conjunction with magnetic stirring bars leads to significantly aggravated metal contamination, consisting of both metal particles and significantly elevated metal ions in solution, the degree of which is several orders of magnitude higher than described for static conditions. Metal particles are analyzed by scanning electron microscopy with electron-dispersive X-ray spectroscopy, and metal content in solution is quantitated at different time points by inductively coupled plasma-mass spectrometry. The concentration of iron, chromium, nickel, and manganese increases with increasing stirring time and speed. We describe the impact of buffer components on the extent of metal particles and ions in solution and illustrate the effect on model proteins. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  3. Probing weld quality monitoring in friction stir welding through characterization of signals by fractal theory

    Energy Technology Data Exchange (ETDEWEB)

    Das, Bipul; Bag, Swarup; Pal, Sukhomay [Indian Institute of Technology Guwahati, Assam (India)

    2017-05-15

    Providing solutions towards the improvisation of welding technologies is the recent trend in the Friction stir welding (FSW) process. We present a monitoring approach for ultimate tensile strength of the friction stir welded joints based on information extracted from process signals through implementing fractal theory. Higuchi and Katz algorithms were executed on current and tool rotational speed signals acquired during friction stir welding to estimate fractal dimensions. Estimated fractal dimensions when correlated with the ultimate tensile strength of the joints deliver an increasing trend with the increase in joint strength. It is observed that dynamicity of the system strengthens the weld joint, i.e., the greater the fractal dimension, the better will be the quality of the weld. Characterization of signals by fractal theory indicates that the single-valued indicator can be an alternative for effective monitoring of the friction stir welding process.

  4. Probing weld quality monitoring in friction stir welding through characterization of signals by fractal theory

    International Nuclear Information System (INIS)

    Das, Bipul; Bag, Swarup; Pal, Sukhomay

    2017-01-01

    Providing solutions towards the improvisation of welding technologies is the recent trend in the Friction stir welding (FSW) process. We present a monitoring approach for ultimate tensile strength of the friction stir welded joints based on information extracted from process signals through implementing fractal theory. Higuchi and Katz algorithms were executed on current and tool rotational speed signals acquired during friction stir welding to estimate fractal dimensions. Estimated fractal dimensions when correlated with the ultimate tensile strength of the joints deliver an increasing trend with the increase in joint strength. It is observed that dynamicity of the system strengthens the weld joint, i.e., the greater the fractal dimension, the better will be the quality of the weld. Characterization of signals by fractal theory indicates that the single-valued indicator can be an alternative for effective monitoring of the friction stir welding process.

  5. Effects of Injection Timing on Fluid Flow Characteristics of Partially Premixed Combustion Based on High-Speed Particle Image Velocimetry

    KAUST Repository

    Izadi Najafabadi, Mohammad; Tanov, Slavey; Wang, Hua; Somers, Bart; Johansson, Bengt; Dam, Nico

    2017-01-01

    behavior. The scope of the present study is to investigate the fluid flow characteristics of PPC at different injection timings. To this end, high-speed Particle Image Velocimetry (PIV) is implemented in a light-duty optical engine to measure fluid flow

  6. Investigation of the motion of diesel injection jets using high-speed cinematography and short time holography

    International Nuclear Information System (INIS)

    Eisfeld, F.

    1987-01-01

    The knowledge about the penetration of diesel injection jets, particularly about the flow within the short behind the nozzle, and the arising of droplets from an injection jet is very limited. Experimental investigations are required to describe the process of penetration and spreading of the jet. The research method requires high speed cinematography and short time holography. Problems in the investigation method are described

  7. Program plan: DWPF/HLWDP stirred Melter Program Plan

    International Nuclear Information System (INIS)

    Smith, M.E.

    1994-01-01

    Slurry Fed Melters (SFM) have been developed in the United States, Europe, and Japan for the conversion of high-level radioactive waste (HLW) to borosilicate glass for permanent disposal. The newest design, the stirred melter, combines the high production rates and high glass quality features of the Joule-heated melters with the low-cost, compact, simple maintenance features of the pot melters. However, further engineering design and demonstrations are needed to operate the stirred melter on a large scale. This document outlines the program which develops a full scale stirred melter for the DWPF (240 pph), and provides a basis which will allow further scale-up of the technology for use in the Hanford High Level Waste Disposal Program (HLWDP) for up to four times the reference capacity

  8. Pre-start timing information is used to set final linear speed in a C-start manoeuvre.

    Science.gov (United States)

    Reinel, Caroline; Schuster, Stefan

    2014-08-15

    In their unique hunting behaviour, archerfish use a complex motor decision to secure their prey: based solely on how dislodged prey initially falls, they select an adapted C-start manoeuvre that turns the fish right towards the point on the water surface where their prey will later land. Furthermore, they take off at a speed that is set so as to arrive in time. We show here that the C-start manoeuvre and not subsequent tail beating is necessary and sufficient for setting this adaptive level of speed. Furthermore, the C-start pattern is adjusted to independently determine both the turning angle and the take-off speed. The selection of both aspects requires no a priori information and is done based on information sampled from the onset of target motion until the C-start is launched. Fin strokes can occur right after the C-start manoeuvre but are not required to fine-tune take-off speed, but rather to maintain it. By probing the way in which the fish set their take-off speed in a wide range of conditions in which distance from the later catching point and time until impact varied widely and unpredictably, we found that the C-start manoeuvre is programmed based on pre-C-start estimates of distance and time until impact. Our study hence provides the first evidence for a C-start that is fine-tuned to produce an adaptive speed level. © 2014. Published by The Company of Biologists Ltd.

  9. Process optimization of friction stir welding based on thermal models

    DEFF Research Database (Denmark)

    Larsen, Anders Astrup

    2010-01-01

    This thesis investigates how to apply optimization methods to numerical models of a friction stir welding process. The work is intended as a proof-of-concept using different methods that are applicable to models of high complexity, possibly with high computational cost, and without the possibility...... information of the high-fidelity model. The optimization schemes are applied to stationary thermal models of differing complexity of the friction stir welding process. The optimization problems considered are based on optimizing the temperature field in the workpiece by finding optimal translational speed....... Also an optimization problem based on a microstructure model is solved, allowing the hardness distribution in the plate to be optimized. The use of purely thermal models represents a simplification of the real process; nonetheless, it shows the applicability of the optimization methods considered...

  10. Analysis and Comparison of Friction Stir Welding and Laser Assisted Friction Stir Welding of Aluminum Alloy.

    Science.gov (United States)

    Campanelli, Sabina Luisa; Casalino, Giuseppe; Casavola, Caterina; Moramarco, Vincenzo

    2013-12-18

    Friction Stir Welding (FSW) is a solid-state joining process; i.e. , no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW) is a combination in which the FSW is the dominant welding process and the laser pre-heats the weld. In this work FSW and LAFSW tests were conducted on 6 mm thick 5754H111 aluminum alloy plates in butt joint configuration. LAFSW is studied firstly to demonstrate the weldability of aluminum alloy using that technique. Secondly, process parameters, such as laser power and temperature gradient are investigated in order to evaluate changes in microstructure, micro-hardness, residual stress, and tensile properties. Once the possibility to achieve sound weld using LAFSW is demonstrated, it will be possible to explore the benefits for tool wear, higher welding speeds, and lower clamping force.

  11. [Hypothesis on the equilibrium point and variability of amplitude, speed and time of single-joint movement].

    Science.gov (United States)

    Latash, M; Gottleib, G

    1990-01-01

    Problems of single-joint movement variability are analysed in the framework of the equilibrium-point hypothesis (the lambda-model). Control of the movements is described with three parameters related to movement amplitude speed, and time. Three strategies emerge from this description. Only one of them is likely to lead to a Fitts' type speed-accuracy trade-off. Experiments were performed to test one of the predictions of the model. Subjects performed identical sets of single-joint fast movements with open or closed eyes and some-what different instructions. Movements performed with closed eyes were characterized with higher peak speeds and unchanged variability in seeming violation of the Fitt's law and in a good correspondence to the model.

  12. A modified time-of-flight method for precise determination of high speed ratios in molecular beams

    Energy Technology Data Exchange (ETDEWEB)

    Salvador Palau, A.; Eder, S. D., E-mail: sabrina.eder@uib.no; Kaltenbacher, T.; Samelin, B.; Holst, B. [Department of Physics and Technology, University of Bergen, Allégaten 55, 5007 Bergen (Norway); Bracco, G. [Department of Physics and Technology, University of Bergen, Allégaten 55, 5007 Bergen (Norway); CNR-IMEM, Department of Physics, University of Genova, V. Dodecaneso 33, 16146 Genova (Italy)

    2016-02-15

    Time-of-flight (TOF) is a standard experimental technique for determining, among others, the speed ratio S (velocity spread) of a molecular beam. The speed ratio is a measure for the monochromaticity of the beam and an accurate determination of S is crucial for various applications, for example, for characterising chromatic aberrations in focussing experiments related to helium microscopy or for precise measurements of surface phonons and surface structures in molecular beam scattering experiments. For both of these applications, it is desirable to have as high a speed ratio as possible. Molecular beam TOF measurements are typically performed by chopping the beam using a rotating chopper with one or more slit openings. The TOF spectra are evaluated using a standard deconvolution method. However, for higher speed ratios, this method is very sensitive to errors related to the determination of the slit width and the beam diameter. The exact sensitivity depends on the beam diameter, the number of slits, the chopper radius, and the chopper rotation frequency. We present a modified method suitable for the evaluation of TOF measurements of high speed ratio beams. The modified method is based on a systematic variation of the chopper convolution parameters so that a set of independent measurements that can be fitted with an appropriate function are obtained. We show that with this modified method, it is possible to reduce the error by typically one order of magnitude compared to the standard method.

  13. Simulation of Vibrations in Real Time Plane Milling with Spindle Speed Correction

    Directory of Open Access Journals (Sweden)

    I. I. Ivanov

    2017-01-01

    Full Text Available In milling the hard-to-machine materials vibrations (chatter often arise from the high cutting forces if a technological system is insufficiently rigid.The main way to suppress these vibrations is to increase a stiffness of the mounting system of the tool and the work-piece to be machined. However, sometimes this method doesn’t lead to desirable result because of high values of intrinsic pliability of the tool and the work-piece. Currently, there are more complicated methods to ensure milling process quality. Among them there are three main groups:mathematical simulation of milling process dynamics and computation of processing parameters which provide high quality of machined surface, low level of vibrations and static deflections of a tool and a work-piece;introduction of the active vibration suppression devices into machine tool design; such devices include a vibration sensor, a feedback circuit, and an actuator which induces kinematic or force action on the oscillatory system;control of processing parameters, mainly of rotation frequency for minimizing the amplitudes of vibrations.The paper studies one of the 3rd group methods. There is a suggestion to process a signal of vibrational accelerations in real time and detect a chatter onset. If the chatter has been detected its frequency is to be identified, and the new value of rotation speed is set:where Ω – rotation frequency, rot/s; p – the tool eigenfrequency value identified during processing, Hz; z – mill tooth number; i – positive integer number; ε<1 – small positive parameter. In the current research it is assumed that ε = 0,2.The formula has been chosen because at the rotation frequency axis where tooth pass frequency is slightly less than the eigenfrequency divided by the integer value there are stable zones of dynamics in the milling process.The study shows a developed model of the plane milling dynamics. It includes a dynamic model of the tool, a model of cutting

  14. Real-time image reconstruction and display system for MRI using a high-speed personal computer.

    Science.gov (United States)

    Haishi, T; Kose, K

    1998-09-01

    A real-time NMR image reconstruction and display system was developed using a high-speed personal computer and optimized for the 32-bit multitasking Microsoft Windows 95 operating system. The system was operated at various CPU clock frequencies by changing the motherboard clock frequency and the processor/bus frequency ratio. When the Pentium CPU was used at the 200 MHz clock frequency, the reconstruction time for one 128 x 128 pixel image was 48 ms and that for the image display on the enlarged 256 x 256 pixel window was about 8 ms. NMR imaging experiments were performed with three fast imaging sequences (FLASH, multishot EPI, and one-shot EPI) to demonstrate the ability of the real-time system. It was concluded that in most cases, high-speed PC would be the best choice for the image reconstruction and display system for real-time MRI. Copyright 1998 Academic Press.

  15. Finding NEMO (novel electromaterial muscle oscillator): a polypyrrole powered robotic fish with real-time wireless speed and directional control

    International Nuclear Information System (INIS)

    McGovern, Scott; Alici, Gursel; Spinks, Geoffrey; Truong, Van-Tan

    2009-01-01

    This paper presents the development of an autonomously powered and controlled robotic fish that incorporates an active flexural joint tail fin, activated through conducting polymer actuators based on polypyrrole (PPy). The novel electromaterial muscle oscillator (NEMO) tail fin assembly on the fish could be controlled wirelessly in real time by varying the frequency and duty cycle of the voltage signal supplied to the PPy bending-type actuators. Directional control was achieved by altering the duty cycle of the voltage input to the NEMO tail fin, which shifted the axis of oscillation and enabled turning of the robotic fish. At low speeds, the robotic fish had a turning circle as small as 15 cm (or 1.1 body lengths) in radius. The highest speed of the fish robot was estimated to be approximately 33 mm s −1 (or 0.25 body lengths s −1 ) and was achieved with a flapping frequency of 0.6–0.8 Hz which also corresponded with the most hydrodynamically efficient mode for tail fin operation. This speed is approximately ten times faster than those for any previously reported artificial muscle based device that also offers real-time speed and directional control. This study contributes to previously published studies on bio-inspired functional devices, demonstrating that electroactive polymer actuators can be real alternatives to conventional means of actuation such as electric motors

  16. Finding NEMO (novel electromaterial muscle oscillator): a polypyrrole powered robotic fish with real-time wireless speed and directional control

    Science.gov (United States)

    McGovern, Scott; Alici, Gursel; Truong, Van-Tan; Spinks, Geoffrey

    2009-09-01

    This paper presents the development of an autonomously powered and controlled robotic fish that incorporates an active flexural joint tail fin, activated through conducting polymer actuators based on polypyrrole (PPy). The novel electromaterial muscle oscillator (NEMO) tail fin assembly on the fish could be controlled wirelessly in real time by varying the frequency and duty cycle of the voltage signal supplied to the PPy bending-type actuators. Directional control was achieved by altering the duty cycle of the voltage input to the NEMO tail fin, which shifted the axis of oscillation and enabled turning of the robotic fish. At low speeds, the robotic fish had a turning circle as small as 15 cm (or 1.1 body lengths) in radius. The highest speed of the fish robot was estimated to be approximately 33 mm s-1 (or 0.25 body lengths s-1) and was achieved with a flapping frequency of 0.6-0.8 Hz which also corresponded with the most hydrodynamically efficient mode for tail fin operation. This speed is approximately ten times faster than those for any previously reported artificial muscle based device that also offers real-time speed and directional control. This study contributes to previously published studies on bio-inspired functional devices, demonstrating that electroactive polymer actuators can be real alternatives to conventional means of actuation such as electric motors.

  17. Mechanical properties and microstructural evaluation of AA1100 to AZ31 dissimilar friction stir welds

    Energy Technology Data Exchange (ETDEWEB)

    Azizieh, M., E-mail: azizieh@gmail.com [Department of Materials Science and Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz (Iran, Islamic Republic of); Sadeghi Alavijeh, A. [School of Mechatronic Systems Engineering, Simon Fraser University, 250-13450 102 Avenue, Surrey, BC V3T 0A3 (Canada); Abbasi, M. [High Temperature Energy Materials, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of); Balak, Z. [Department of Materials Science and Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz (Iran, Islamic Republic of); Kim, H.S. [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang, 790-784 (Korea, Republic of)

    2016-02-15

    In this paper, microstructure and mechanical properties of dissimilar friction stir welds of AA1100 and AZ31 were investigated to understand the effects of rotational and travel speed as well as pin position. The tensile results of welded samples revealed that the sound welds were formed when the stirring pin deviated from the centreline to the AZ31 side. The X-ray diffraction shows that Al{sub 3}Mg{sub 2} and Al{sub 12}Mg{sub 17} intermetallics formation occurs in the stir zone during the welding process. High hardness of these intermetallic phases increased the hardness of the stir zone to 110 Hv. The best tensile results were obtained in the sample processed in the range of 28–32 (rev/mm) rotational to travel speed ratio. - Highlights: • For Al to Mg friction stir welding, tool offset must be to Mg side. • There is an optimum rotational speed for obtain the highest strength. • Intermetallics form in any welding condition. • The volume fraction of intermetallic is directly related to FSW peak temperature.

  18. Pulsed ultrasonic stir welding system

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2013-01-01

    An ultrasonic stir welding system includes a welding head assembly having a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. During a welding operation, ultrasonic pulses are applied to the rod as it rotates about its longitudinal axis. The ultrasonic pulses are applied in such a way that they propagate parallel to the longitudinal axis of the rod.

  19. Optimization of operating variables for production of ultra-fine talc in a stirred mill. Specific surface area investigations

    Directory of Open Access Journals (Sweden)

    Toraman Oner Yusuf

    2016-01-01

    Full Text Available Due to its properties such as chemical inertness, softness, whiteness, high thermal conductivity, low electrical conductivity and adsorption properties talc has wide industrial applications in paper, cosmetics, paints, polymer, ceramics, refractory materials and pharmaceutical. The demand for ultra-fine talc is emerging which drives the mineral industry to produce value added products. In this study, it was investigated how certain grinding parameters such as mill speed, ball filling ratio, powder filling ratio and grinding time of dry stirred mill affect grindability of talc ore (d97=127 μm. A series of laboratory experiments using a 24 full factorial design was conducted to determine the optimal operational parameters of a stirred mill in order to minimize the specific surface area. The main and interaction effects on the volume specific surface area (SV, m2.cm−3 of the ground product were evaluated using the Yates analysis. Under the optimal conditions at the stirrer speed of 600 rpm, grinding time of 20 min, sample mass of 5% and ball ratio of 70%, the resulting talc powder had larger volume specific surface area (i.e., 3.48 m2.cm−3 than the starting material (i.e., 1.84 m2.cm−3.

  20. Microstructure and Mechanical Performance of Friction Stir Spot-Welded Aluminum-5754 Sheets

    Science.gov (United States)

    Pathak, N.; Bandyopadhyay, K.; Sarangi, M.; Panda, Sushanta Kumar

    2013-01-01

    Friction stir spot welding (FSSW) is a recent trend of joining light-weight sheet metals while fabricating automotive and aerospace body components. For the successful application of this solid-state welding process, it is imperative to have a thorough understanding of the weld microstructure, mechanical performance, and failure mechanism. In the present study, FSSW of aluminum-5754 sheet metal was tried using tools with circular and tapered pin considering different tool rotational speeds, plunge depths, and dwell times. The effects of tool design and process parameters on temperature distribution near the sheet-tool interface, weld microstructure, weld strength, and failure modes were studied. It was found that the peak temperature was higher while welding with a tool having circular pin compared to tapered pin, leading to a bigger dynamic recrystallized stir zone (SZ) with a hook tip bending towards the upper sheet and away from the keyhole. Hence, higher lap shear separation load was observed in the welds made from circular pin compared to those made from tapered pin. Due to influence of size and hardness of SZ on crack propagation, three different failure modes of weld nugget were observed through optical cross-sectional micrograph and SEM fractographs.

  1. Mass Transfer Coefficientin Stirred Tank for p -Cresol Extraction Process from Coal Tar

    International Nuclear Information System (INIS)

    Fardhyanti, D S; Tyaningsih, D S; Afifah, S N

    2017-01-01

    Indonesia is a country that has a lot of coal resources. The Indonesian coal has a low caloric value. Pyrolysis is one of the process to increase the caloric value. One of the by-product of the pyrolysis process is coal tar. It contains a lot of aliphatic or aromatic compounds such as p -cresol (11% v/v). It is widely used as a disinfectant. Extractionof p -Cresol increases the economic value of waste of coal. The aim of this research isto study about mass tranfer coefficient in the baffled stirred tank for p -Cresolextraction from coal tar. Mass transfer coefficient is useful for design and scale up of industrial equipment. Extraction is conducted in the baffled stirred tank equipped with a four-bladed axial impeller placed vertically in the vessel. Sample for each time processing (5, 10, 15, 20, 25 and 30minutes) was poured into a separating funnel, settled for an hour and separated into two phases. Then the two phases were weighed. The extract phases and raffinate phases were analyzed by Spectronic UV-Vis. The result showed that mixing speed of p -Cresol extraction increasesthe yield of p -Cresol and the mass transfer coefficient. The highest yield of p -Cresol is 49.32% and the highest mass transfer coefficient is 4.757 x 10 -6 kg/m 2 s. (paper)

  2. Mass Transfer Coefficientin Stirred Tank for p-Cresol Extraction Process from Coal Tar

    Science.gov (United States)

    Fardhyanti, D. S.; Tyaningsih, D. S.; Afifah, S. N.

    2017-04-01

    Indonesia is a country that has a lot of coal resources. The Indonesian coal has a low caloric value. Pyrolysis is one of the process to increase the caloric value. One of the by-product of the pyrolysis process is coal tar. It contains a lot of aliphatic or aromatic compounds such asp-cresol (11% v/v). It is widely used as a disinfectant. Extractionof p-Cresol increases the economic value of waste of coal. The aim of this research isto study about mass tranfer coefficient in the baffled stirred tank for p-Cresolextraction from coal tar. Mass transfer coefficient is useful for design and scale up of industrial equipment. Extraction is conducted inthe baffled stirred tank equipped with a four-bladed axial impeller placed vertically in the vessel. Sample for each time processing (5, 10, 15, 20, 25 and 30minutes) was poured into a separating funnel, settled for an hour and separated into two phases. Then the two phases were weighed. The extract phases and raffinate phases were analyzed by Spectronic UV-Vis. The result showed that mixing speed of p-Cresol extraction increasesthe yield of p-Cresol and the mass transfer coefficient. The highest yield of p-Cresol is 49.32% and the highest mass transfer coefficient is 4.757 x 10-6kg/m2s.

  3. Flexible Friction Stir Joining Technology

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Zhili [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lim, Yong Chae [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mahoney, Murray [MegaStir Technologies LLC, Orem, UT (United States); Sanderson, Samuel [MegaStir Technologies LLC, Orem, UT (United States); Larsen, Steve [MegaStir Technologies LLC, Orem, UT (United States); Steel, Russel [MegaStir Technologies LLC, Orem, UT (United States); Fleck, Dale [MegaStir Technologies LLC, Orem, UT (United States); Fairchild, Doug P [ExxonMobil, Upstream Research Company (URC), Houston, TX (United States); Wasson, Andrew J [ExxonMobil, Upstream Research Company (URC), Houston, TX (United States); Babb, Jon [MegaStir Technologies LLC, Orem, UT (United States); Higgins, Paul [MegaStir Technologies LLC, Orem, UT (United States)

    2015-07-23

    Reported herein is the final report on a U.S. Department of Energy (DOE) Advanced Manufacturing Office (AMO) project with industry cost-share that was jointly carried out by Oak Ridge National Laboratory (ORNL), ExxonMobil Upstream Research Company (ExxonMobil), and MegaStir Technologies (MegaStir). The project was aimed to advance the state of the art of friction stir welding (FSW) technology, a highly energy-efficient solid-state joining process, for field deployable, on-site fabrications of large, complex and thick-sectioned structures of high-performance and high-temperature materials. The technology innovations developed herein attempted to address two fundamental shortcomings of FSW: 1) the inability for on-site welding and 2) the inability to weld thick section steels, both of which have impeded widespread use of FSW in manufacturing. Through this work, major advance has been made toward transforming FSW technology from a “specialty” process to a mainstream materials joining technology to realize its pervasive energy, environmental, and economic benefits across industry.

  4. The value of STIR sequence in the characterization of mediastinal lymph nodes

    Directory of Open Access Journals (Sweden)

    Aylin Okur

    2013-12-01

    Full Text Available INTRODUCTION: To investigate availability of Short Time Inversion Recovery Turbo Spin Echo Magnetic Resonance imaging (STIR TSE MRI in the detection of mediastinal lymph nodes and in the distinguishing malign and benign lymph nodes detected in cases with pulmonary lesions. METHODS: Overall, 46 patients having mediastinal lymph nodes with confirmed or suspected lung cancer were included to the study. All patients underwent STIR TSE MR imaging before mediastinoscopy. Lymph nodes were assessed by signal characteristics on STIR TSE MRI. The results of histopathological evaluation and STIR TSE MRI were compared after mediastinoscopy. As data were qualitative, distributions were expressed as percentage and chi-square test was used to determine the difference between variables. RESULTS: Overall, 92 lymph nodes were analyzed. When a comparison was made between malign and benign lymph nodes, a significant difference was found between STIR MRI signal properties of lymph nodes and lymph node size. The specificity, sensitivity, positive predictive value and negative predictive value of STIR TSE MRI were estimated as 75.0%, 75.0%, 61.5% and 83.3%, respectively. DISCUSSION AND CONCLUSION: Although the negative predictive value is high in STIR TSE MRI, it has a low positive predictive value. Thus, the case may directly undergo surgery without performing mediastinoscopy when no malign lymph node is detected in STIR TSE MRI, while mediastinoscopy is warranted when a malign lymph node is detected.

  5. A Real-Time Method to Estimate Speed of Object Based on Object Detection and Optical Flow Calculation

    Science.gov (United States)

    Liu, Kaizhan; Ye, Yunming; Li, Xutao; Li, Yan

    2018-04-01

    In recent years Convolutional Neural Network (CNN) has been widely used in computer vision field and makes great progress in lots of contents like object detection and classification. Even so, combining Convolutional Neural Network, which means making multiple CNN frameworks working synchronously and sharing their output information, could figure out useful message that each of them cannot provide singly. Here we introduce a method to real-time estimate speed of object by combining two CNN: YOLOv2 and FlowNet. In every frame, YOLOv2 provides object size; object location and object type while FlowNet providing the optical flow of whole image. On one hand, object size and object location help to select out the object part of optical flow image thus calculating out the average optical flow of every object. On the other hand, object type and object size help to figure out the relationship between optical flow and true speed by means of optics theory and priori knowledge. Therefore, with these two key information, speed of object can be estimated. This method manages to estimate multiple objects at real-time speed by only using a normal camera even in moving status, whose error is acceptable in most application fields like manless driving or robot vision.

  6. Two-dimensional nonlinear dynamics of an axially moving viscoelastic beam with time-dependent axial speed

    International Nuclear Information System (INIS)

    Ghayesh, Mergen H.; Amabili, Marco; Farokhi, Hamed

    2013-01-01

    In the present study, the coupled nonlinear dynamics of an axially moving viscoelastic beam with time-dependent axial speed is investigated employing a numerical technique. The equations of motion for both the transverse and longitudinal motions are obtained using Newton’s second law of motion and the constitutive relations. A two-parameter rheological model of the Kelvin–Voigt energy dissipation mechanism is employed in the modelling of the viscoelastic beam material, in which the material time derivative is used in the viscoelastic constitutive relation. The Galerkin method is then applied to the coupled nonlinear equations, which are in the form of partial differential equations, resulting in a set of nonlinear ordinary differential equations (ODEs) with time-dependent coefficients due to the axial acceleration. A change of variables is then introduced to this set of ODEs to transform them into a set of first-order ordinary differential equations. A variable step-size modified Rosenbrock method is used to conduct direct time integration upon this new set of first-order nonlinear ODEs. The mean axial speed and the amplitude of the speed variations, which are taken as bifurcation parameters, are varied, resulting in the bifurcation diagrams of Poincaré maps of the system. The dynamical characteristics of the system are examined more precisely via plotting time histories, phase-plane portraits, Poincaré sections, and fast Fourier transforms (FFTs)

  7. Atmospheric pressure gas chromatography-time-of-flight-mass spectrometry (APGC-ToF-MS) for the determination of regulated and emerging contaminants in aqueous samples after stir bar sorptive extraction (SBSE).

    Science.gov (United States)

    Pintado-Herrera, Marina G; González-Mazo, Eduardo; Lara-Martín, Pablo A

    2014-12-03

    This work presents the development, optimization and validation of a multi-residue method for the simultaneous determination of 102 contaminants, including fragrances, UV filters, repellents, endocrine disruptors, biocides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and several types of pesticides in aqueous matrices. Water samples were processed using stir bar sorptive extraction (SBSE) after the optimization of several parameters: agitation time, ionic strength, presence of organic modifiers, pH, and volume of the derivatizing agent. Target compounds were extracted from the bars by liquid desorption (LD). Separation, identification and quantification of analytes were carried out by gas chromatography (GC) coupled to time-of-flight (ToF-MS) mass spectrometry. A new ionization source, atmospheric pressure gas chromatography (APGC), was tested. The optimized protocol showed acceptable recovery percentages (50-100%) and limits of detection below 1ngL(-1) for most of the compounds. Occurrence of 21 out of 102 analytes was confirmed in several environmental aquatic matrices, including seawater, sewage effluent, river water and groundwater. Non-target compounds such as organophosphorus flame retardants were also identified in real samples by accurate mass measurement of their molecular ions using GC-APGC-ToF-MS. To the best of our knowledge, this is the first time that this technique has been applied for the analysis of contaminants in aquatic systems. By employing lower energy than the more widely used electron impact ionization (EI), AGPC provides significant advantages over EI for those substances very susceptible to high fragmentation (e.g., fragrances, pyrethroids). Copyright © 2014 Elsevier B.V. All rights reserved.

  8. 3D simulation of friction stir welding based on movable cellular automaton method

    Science.gov (United States)

    Eremina, Galina M.

    2017-12-01

    The paper is devoted to a 3D computer simulation of the peculiarities of material flow taking place in friction stir welding (FSW). The simulation was performed by the movable cellular automaton (MCA) method, which is a representative of particle methods in mechanics. Commonly, the flow of material in FSW is simulated based on computational fluid mechanics, assuming the material as continuum and ignoring its structure. The MCA method considers a material as an ensemble of bonded particles. The rupture of interparticle bonds and the formation of new bonds enable simulations of crack nucleation and healing as well as mas mixing and microwelding. The simulation results showed that using pins of simple shape (cylinder, cone, and pyramid) without a shoulder results in small displacements of plasticized material in workpiece thickness directions. Nevertheless, the optimal ratio of longitudinal velocity to rotational speed makes it possible to transport the welded material around the pin several times and to produce a joint of good quality.

  9. Biodegradation of phenolic waste liquors in stirred-tank, packed-bed, and fluidized-bed bioreactors

    Energy Technology Data Exchange (ETDEWEB)

    Holladay, D W; Hancher, G W; Chilcote, D D; Scott, C D

    1978-11-01

    The biological degradation of phenolic scrub liquors similar to those that arise in coal conversion processes was studied for symbiotic bacterial populations contained in a continuously stirred tank bioreactor, a three-phase packed-bed bioreactor, and a three-phase, fluidized-bed bioreactor. The conversions of phenol compounds were comparable in the three-phase, packed-bed bioreactor and the continuously stirred tank bioreactor; however, the packed-bed bioreactor degradation rates were as much as twice those in the continuously stirred tank bioreactor, and packed-bed bioreactor retention times were as low as one- tenth those of the continuously stirred tank bioreactors (minimum time was 12 hours).

  10. Serial quantitative MR assessment of optic neuritis in a case of neuromyelitis optica, using gadolinium-'enhanced' STIR imaging

    International Nuclear Information System (INIS)

    Barkhof, F.; Scheltens, P.; Valk, J.; Waalewijn, C.; Uitdehaag, B.M.J.; Polman, C.H.

    1991-01-01

    A patient is presented with neuromyelitis optica. MR imaging, using a short inversion time inversion recovery (STIR) technique, clearly depicted the lesion in the left optic nerve. Subsequent serial STIR imaging, with and without Gadolinium-DTPA, allowed quantitative assessment of changes parallel to improved optic nerve function. STIR imaging is a sensitive technique to demonstrate optic nerve lesions, and enables quantitative assessment to be made of the effect of (steroid) medication. (orig.)

  11. STIR imaging of lymphadenopathy: Advantages over conventional spin-echo techniques

    International Nuclear Information System (INIS)

    Porter, B.A.; Neumann, E.B.; Olson, D.O.; Nyberg, D.A.; Teefy, S.A.; Shields, A.F.

    1987-01-01

    Spin-echo (SE) imaging of lymphadenopathy has been limited by the high signal of surrounding fat. With short TI Inversion Recovery (STIR), fat is cancelled (black), T1 and T2 contrast are additive, and pathologic nodes are white. STIR images (repetition time, 1,400 - 2,400; echo time, 36 or 40; inversion time, 100 or 125) of 69 patients with malignant adenopathy were compared with T1-weighted spin-echo (T1 SE) or intermediate SE and some T2 SE sequences at 0.15 T. Signal-intensity measurements of nodes versus adjacent tissues were used as a measure of contrast. Ratios of these values ranged from 2.5- to more than 17-fold greater for STIR versus T1 or intermediate SE sequences and to more than 40:1 for STIR versus T2 SE images. Some nodes detected on STIR were only identifiable in retrospection CT or T1 SE. In two cases, STIR detected minimally enlarged nodes not detected on CT; biopsy confirmed malignancy. Normal nodes have lower signal than malignant nodes; inflammatory nodes may mimic neoplasm. The authors replaced T2 SE with a combination of T1 SE and STIR, shortening imaging time and enhancing detection of lymphadenopathy

  12. Low-field STIR imaging of avascular necrosis, marrow edema, and infarction

    International Nuclear Information System (INIS)

    Porter, B.A.; Schwartz, A.N.; Olson, D.O.

    1987-01-01

    Based on 12 months experience with low-field (0.15-T) short-T1 inversion recovery (STIR) imaging, the authors replaced T2-weighted spin echo (T2SE) images with STIR for avascular necrosis (AVN). With STIR (repetition time 1,600 echo time 36, inversion time 100, 2 Avg, 256 x 128), fat is black and edema or joint fluid is bright white; 14 contiguous images take less than 7 minutes and have much greater contrast than T1 or T2 SE images. MR examinations of 36 patients with suspected AVN, marrow edema, or infarction were reviewed. AVN was equally well diagnosed with T1 SE and STIR in 16 of 16 patients. However, small effusions and the extent of marrow edema or infarction were better delineated on STIR. Joints with effusions were almost always symptomatic. Asymptomatic AVN was detected and confirmed by pressure measurements. AVN or asymptomatic marrow infarction was detected in four of six renal transplant patients. Serial STIR imaging may allow clinical monitoring of AVN. STIR improves detection of effusion, permits shorter imaging time, and can replace T2SE for AVN

  13. Artificial neural networks application for modeling of friction stir welding effects on mechanical properties of 7075-T6 aluminum alloy

    Science.gov (United States)

    Maleki, E.

    2015-12-01

    Friction stir welding (FSW) is a relatively new solid-state joining technique that is widely adopted in manufacturing and industry fields to join different metallic alloys that are hard to weld by conventional fusion welding. Friction stir welding is a very complex process comprising several highly coupled physical phenomena. The complex geometry of some kinds of joints makes it difficult to develop an overall governing equations system for theoretical behavior analyse of the friction stir welded joints. Weld quality is predominantly affected by welding effective parameters, and the experiments are often time consuming and costly. On the other hand, employing artificial intelligence (AI) systems such as artificial neural networks (ANNs) as an efficient approach to solve the science and engineering problems is considerable. In present study modeling of FSW effective parameters by ANNs is investigated. To train the networks, experimental test results on thirty AA-7075-T6 specimens are considered, and the networks are developed based on back propagation (BP) algorithm. ANNs testing are carried out using different experimental data that they are not used during networks training. In this paper, rotational speed of tool, welding speed, axial force, shoulder diameter, pin diameter and tool hardness are regarded as inputs of the ANNs. Yield strength, tensile strength, notch-tensile strength and hardness of welding zone are gathered as outputs of neural networks. According to the obtained results, predicted values for the hardness of welding zone, yield strength, tensile strength and notch-tensile strength have the least mean relative error (MRE), respectively. Comparison of the predicted and the experimental results confirms that the networks are adjusted carefully, and the ANN can be used for modeling of FSW effective parameters.

  14. Artificial neural networks application for modeling of friction stir welding effects on mechanical properties of 7075-T6 aluminum alloy

    International Nuclear Information System (INIS)

    Maleki, E

    2015-01-01

    Friction stir welding (FSW) is a relatively new solid-state joining technique that is widely adopted in manufacturing and industry fields to join different metallic alloys that are hard to weld by conventional fusion welding. Friction stir welding is a very complex process comprising several highly coupled physical phenomena. The complex geometry of some kinds of joints makes it difficult to develop an overall governing equations system for theoretical behavior analyse of the friction stir welded joints. Weld quality is predominantly affected by welding effective parameters, and the experiments are often time consuming and costly. On the other hand, employing artificial intelligence (AI) systems such as artificial neural networks (ANNs) as an efficient approach to solve the science and engineering problems is considerable. In present study modeling of FSW effective parameters by ANNs is investigated. To train the networks, experimental test results on thirty AA-7075-T6 specimens are considered, and the networks are developed based on back propagation (BP) algorithm. ANNs testing are carried out using different experimental data that they are not used during networks training. In this paper, rotational speed of tool, welding speed, axial force, shoulder diameter, pin diameter and tool hardness are regarded as inputs of the ANNs. Yield strength, tensile strength, notch-tensile strength and hardness of welding zone are gathered as outputs of neural networks. According to the obtained results, predicted values for the hardness of welding zone, yield strength, tensile strength and notch-tensile strength have the least mean relative error (MRE), respectively. Comparison of the predicted and the experimental results confirms that the networks are adjusted carefully, and the ANN can be used for modeling of FSW effective parameters. (paper)

  15. Real-time interferometer phase detection using an LSI-11 microcomputer and high-speed digital techniques

    International Nuclear Information System (INIS)

    Mendell, D.S.

    1978-01-01

    This paper describes the basic design and philosophy of a real-time, interferometer phase-detection system used on the 2XIIB and TMX magnetic-fusion experiments at the Lawrence Livermore Laboratory. This diagnostics system is now a satellite to a host computer and uses high-speed, emitter-coupled logic techniques to derive data on real-time phase relationships. The system's input signals can be derived from interferometer outputs over a wide range of reference frequencies. An LSI-11 microcomputer is the interface between the high-speed phase-detection logic, buffer memory, human interaction, and host computer. Phase data on a storage CRT is immediately displayed after each experimental fusion shot. An operator can interrogate this phase data more closely from an interactive control panel, while the host computer is simultaneously examining the system's buffer memory or arming the system for the next shot

  16. Real Time Implementation of a DC Motor Speed Control by Fuzzy Logic Controller and PI Controller Using FPGA

    Directory of Open Access Journals (Sweden)

    G. Sakthivel

    2010-10-01

    Full Text Available Fuzzy logic control has met with growing interest in many motor control applications due to its non-linearity, handling features and independence of plant modelling. The hardware implementation of fuzzy logic controller (FLC on FPGA is very important because of the increasing number of fuzzy applications requiring highly parallel and high speed fuzzy processing. Implementation of a fuzzy logic controller and conventional PI controller on an FPGA using VHDL for DC motor speed control is presented in this paper. The proposed scheme is to improve tracking performance of D.C. motor as compared to the conventional (PI control strategy .This paper describes the hardware implementation of two inputs (error and change in error, one output fuzzy logic controller based on PI controller and conventional PI controller using VHDL. Real time implementation FLC and conventional PI controller is made on Spartan-3A DSP FPGA (XC3SD1800A FPGA for the speed control of DC motor. It is observed that fuzzy logic based controllers give better responses than the conventional PI controller for the speed control of dc motor.

  17. Constant versus variable response signal delays in speed accuracy trade-offs : Effects of advance preparation for processing time

    OpenAIRE

    Miller, Jeff; Sproesser, Gudrun; Ulrich, Rolf

    2008-01-01

    In two experiments, we used response signals (RSs) to control processing time and trace out speed accuracy trade-off (SAT) functions in a difficult perceptual discrimination task. Each experiment compared performance in blocks of trials with constant and, hence, temporally predictable RS lags against performance in blocks with variable, unpredictable RS lags. In both experiments, essentially equivalent SAT functions were observed with constant and variable RS lags. We conclude that there is l...

  18. Periodic fluctuations in correlation-based connectivity density time series: Application to wind speed-monitoring network in Switzerland

    Science.gov (United States)

    Laib, Mohamed; Telesca, Luciano; Kanevski, Mikhail

    2018-02-01

    In this paper, we study the periodic fluctuations of connectivity density time series of a wind speed-monitoring network in Switzerland. By using the correlogram-based robust periodogram annual periodic oscillations were found in the correlation-based network. The intensity of such annual periodic oscillations is larger for lower correlation thresholds and smaller for higher. The annual periodicity in the connectivity density seems reasonably consistent with the seasonal meteo-climatic cycle.

  19. Stanford test called a net breakthrough - data sent at 3,500 times the speed of broadband

    CERN Multimedia

    2003-01-01

    Researchers at a Stanford University-affiliated research center have found a way to send data across the Internet more than 3,500 times faster than the typical broadband connection. The technical breakthrough set an Internet speed record too fast to be of use with present-day computers but could open the way for scientists to share and ship massive databases around the world, according to the researchers.

  20. Physics in a general length space-time geometry: Call for experimental revision of the light speed anisotropy

    OpenAIRE

    Exirifard, Qasem

    2013-01-01

    We present a phenomenological model for the nature in the Finsler and Randers space-time geometries. We show that the parity-odd light speed anisotropy perpendicular to the gravitational equipotential surfaces encodes the deviation from the Riemann geometry toward the Randers geometry. We utilize an asymmetrical ring resonator and propose a setup in order to directly measure this deviation. We address the constraints that the current technology will impose on the deviation should the anisotro...

  1. Connecting speeds, directions and arrival times of 22 coronal mass ejections from the sun to 1 AU

    Energy Technology Data Exchange (ETDEWEB)

    Möstl, C.; Veronig, A. M.; Rollett, T.; Temmer, M.; Peinhart, V. [Kanzelhöhe Observatory-IGAM, Institute of Physics, University of Graz (Austria); Amla, K.; Hall, J. R.; Liewer, P. C.; De Jong, E. M. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA (United States); Colaninno, R. C. [Space Sciences Division, Naval Research Laboratory, Washington, DC (United States); Davies, J. A.; Harrison, R. A. [RAL Space, Harwell Oxford, Didcot (United Kingdom); Lugaz, N.; Farrugia, C. J.; Galvin, A. B. [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH (United States); Liu, Y. D. [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing (China); Luhmann, J. G. [Space Science Laboratory, University of California, Berkeley, CA (United States); Vršnak, B., E-mail: christian.moestl@uni-graz.at [Hvar Observatory, Faculty of Geodesy, University of Zagreb, Kačićeva 26, HR-10000, Zagreb (Croatia)

    2014-06-01

    Forecasting the in situ properties of coronal mass ejections (CMEs) from remote images is expected to strongly enhance predictions of space weather and is of general interest for studying the interaction of CMEs with planetary environments. We study the feasibility of using a single heliospheric imager (HI) instrument, imaging the solar wind density from the Sun to 1 AU, for connecting remote images to in situ observations of CMEs. We compare the predictions of speed and arrival time for 22 CMEs (in 2008-2012) to the corresponding interplanetary coronal mass ejection (ICME) parameters at in situ observatories (STEREO PLASTIC/IMPACT, Wind SWE/MFI). The list consists of front- and backsided, slow and fast CMEs (up to 2700 km s{sup –1}). We track the CMEs to 34.9 ± 7.1 deg elongation from the Sun with J maps constructed using the SATPLOT tool, resulting in prediction lead times of –26.4 ± 15.3 hr. The geometrical models we use assume different CME front shapes (fixed-Φ, harmonic mean, self-similar expansion) and constant CME speed and direction. We find no significant superiority in the predictive capability of any of the three methods. The absolute difference between predicted and observed ICME arrival times is 8.1 ± 6.3 hr (rms value of 10.9 hr). Speeds are consistent to within 284 ± 288 km s{sup –1}. Empirical corrections to the predictions enhance their performance for the arrival times to 6.1 ± 5.0 hr (rms value of 7.9 hr), and for the speeds to 53 ± 50 km s{sup –1}. These results are important for Solar Orbiter and a space weather mission positioned away from the Sun-Earth line.

  2. Study of Low Flow Rate Ladle Bottom Gas Stirring Using Triaxial Vibration Signals

    Science.gov (United States)

    Yenus, Jaefer; Brooks, Geoffrey; Dunn, Michelle; Li, Zushu; Goodwin, Tim

    2018-02-01

    Secondary steelmaking plays a great role in enhancing the quality of the final steel product. The metal quality is a function of metal bath stirring in ladles. The metal bath is often stirred by an inert gas to achieve maximum compositional and thermal uniformity throughout the melt. Ladle operators often observe the top surface phenomena, such as level of meniscus disturbance, to evaluate the status of stirring. However, this type of monitoring has significant limitations in assessing the process accurately especially at low gas flow rate bubbling. The present study investigates stirring phenomena using ladle wall triaxial vibration at a low flow rate on a steel-made laboratory model and plant scale for the case of the vacuum tank degasser. Cold model and plant data were successfully modeled by partial least-squares regression to predict the amount of stirring. In the cold model, it was found that the combined vibration signal could predict the stirring power and recirculation speed effectively in specific frequency ranges. Plant trials also revealed that there is a high structure in each data set and in the same frequency ranges at the water model. In the case of industrial data, the degree of linear relationship was strong for data taken from a single heat.

  3. Real-time monitoring of viscosity changes triggered by chemical reactions using a high-speed imaging method

    Directory of Open Access Journals (Sweden)

    Wooseok Jung

    2015-09-01

    Full Text Available We present a method to monitor in real time peptide self-assembly or polymerization events. The temperature controlled modification of a previously reported splash test setup using high speed imaging enables to observe and measure rheological changes in liquid samples and can, in turn, monitor a peptide self-assembly or polymerization reaction accompanied with specific changes in solution viscosity. A series of 2 mm glass beads were dropped into an Fmoc-L3-OMe (methylated Fluorenylmethyloxycarbonyl-trileucine solution mixed with Alcalase 2.4 L (EC 3.4.21.62 or first dipped in Tetramethylethylenediamine (TEMED, a catalyst for acrylamide polymerization, then dropped into acrylamide. The resulting splashes were observed using a high speed camera. The results demonstrate that the viscosity changes of the peptide sample during the peptide self-assembly or acrylamide polymerization affect the specific shape and evolution of the splashing event. Typically, the increase in viscosity while the reaction occurs decreased the size of the splash and the amount of time for the splash to reach maximum extension from the moment for the beads to impact the sample. The ability to observe rheological changes of sample state presents the opportunity to monitor the real time dynamics of peptide self-assembly or cross-polymerization. Keywords: High-speed imaging, Self-assembly, Viscosity sensor

  4. Development of a process envelope for friction stir welding of DH36 steel – A step change

    International Nuclear Information System (INIS)

    Toumpis, Athanasios; Galloway, Alexander; Cater, Stephen; McPherson, Norman

    2014-01-01

    Highlights: • The friction stir welding speed on DH36 steel has been substantially increased. • Excellent quality welds offering potential economic advantages are obtained. • Friction stir welding of steel generates a very complex metallurgical system. • Slow and intermediate welding speed tensile samples fractured in the parent material. • Increasing traverse speed is seen to improve the impact toughness of the weld. - Abstract: Friction stir welding of steel presents an array of advantages across many industrial sectors compared to conventional fusion welding techniques. However, the fundamental knowledge of the friction stir welding process in relation to steel remains relatively limited. A microstructure and property evaluation of friction stir welded low alloy steel grade DH36 plate, commonly used in ship and marine applications has been undertaken. In this comprehensive study, plates of 2000 × 200 × 6 mm were butt welded together at varying rotational and traverse speeds. Samples were examined microscopically and by transverse tensile tests. In addition, the work was complemented by Charpy impact testing and micro-hardness testing in various regions of the weld. The study examined a wide range of process parameters; from this, a preliminary process parameter envelope has been developed and initial process parameter sets established that produce commercially attractive excellent quality welds through a substantial increase in the conventionally recognised weld traverse speed

  5. Counterrotating-Shoulder Mechanism for Friction Stir Welding

    Science.gov (United States)

    Nunes, Arthur C., Jr.

    2007-01-01

    upper and lower bevel gears. The lower bevel gear would be attached to the upper shoulder and would slide and rotate freely over the spindle. The spindle would be fastened by its threaded upper end to an external submechanism that would exert axial tension on the spindle to load the workpiece in compression between the shoulders. By reducing or eliminating (relative to the use of a self reacting tool) the torque that must be reacted externally, the use of the proposed tool would reduce the tendency toward distortion or slippage of the workpiece. To begin a weld, the spindle would be inserted through a hole in the workpiece or run-on tab at the beginning of the seam and fastened to the loading submechanism. Rotation and axial loading would be increased gradually from zero and, after a time to be determined by trial and error, translation along the weld seam would be increased gradually from zero to a steady weld speed. The weld would be ended by running the mechanism off the workpiece or, if the lower shoulder were detachable, by detaching the lower shoulder from the spindle and pulling the pin tool out.

  6. Friction stir welding (FSW of aluminium foam sandwich panels

    Directory of Open Access Journals (Sweden)

    M. Bušić

    2016-07-01

    Full Text Available The article focuses on the influence of welding speed and tool tilt angle upon the mechanical properties at the friction stir welding of aluminium foam sandwich panels. Double side welding was used for producing butt welds of aluminium sandwich panels applying insertion of extruded aluminium profile. Such insertion provided lower pressure of the tool upon the aluminium panels, providing also sufficient volume of the material required for the weldment formation. Ultimate tensile strength and flexural strength for three-point bending test have been determined for samples taken from the welded joints. Results have confirmed anticipated effects of independent variables.

  7. Pulsed ultrasonic stir welding method

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2013-01-01

    A method of performing ultrasonic stir welding uses a welding head assembly to include a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. In the method, the rod is rotated about its longitudinal axis during a welding operation. During the welding operation, a series of on-off ultrasonic pulses are applied to the rod such that they propagate parallel to the rod's longitudinal axis. At least a pulse rate associated with the on-off ultrasonic pulses is controlled.

  8. Area, speed and power measurements of FPGA-based complex orthogonal space-time block code channel encoders

    Science.gov (United States)

    Passas, Georgios; Freear, Steven; Fawcett, Darren

    2010-01-01

    Space-time coding (STC) is an important milestone in modern wireless communications. In this technique, more copies of the same signal are transmitted through different antennas (space) and different symbol periods (time), to improve the robustness of a wireless system by increasing its diversity gain. STCs are channel coding algorithms that can be readily implemented on a field programmable gate array (FPGA) device. This work provides some figures for the amount of required FPGA hardware resources, the speed that the algorithms can operate and the power consumption requirements of a space-time block code (STBC) encoder. Seven encoder very high-speed integrated circuit hardware description language (VHDL) designs have been coded, synthesised and tested. Each design realises a complex orthogonal space-time block code with a different transmission matrix. All VHDL designs are parameterisable in terms of sample precision. Precisions ranging from 4 bits to 32 bits have been synthesised. Alamouti's STBC encoder design [Alamouti, S.M. (1998), 'A Simple Transmit Diversity Technique for Wireless Communications', IEEE Journal on Selected Areas in Communications, 16:55-108.] proved to be the best trade-off, since it is on average 3.2 times smaller, 1.5 times faster and requires slightly less power than the next best trade-off in the comparison, which is a 3/4-rate full-diversity 3Tx-antenna STBC.

  9. Search for scalar-tensor gravity theories with a non-monotonic time evolution of the speed-up factor

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, A [Dept Fisica, Universidad de Murcia, E30071-Murcia (Spain); Serna, A [Dept Fisica, Computacion y Comunicaciones, Universidad Miguel Hernandez, E03202-Elche (Spain); Alimi, J-M [Lab. de l' Univers et de ses Theories (LUTH, CNRS FRE2462), Observatoire de Paris-Meudon, F92195-Meudon (France)

    2002-08-21

    We present a method to detect, in the framework of scalar-tensor gravity theories, the existence of stationary points in the time evolution of the speed-up factor. An attractive aspect of this method is that, once the particular scalar-tensor theory has been specified, the stationary points are found through a simple algebraic equation which does not contain any integration. By applying this method to the three classes of scalar-tensor theories defined by Barrow and Parsons, we have found several new cosmological models with a non-monotonic evolution of the speed-up factor. The physical interest of these models is that, as previously shown by Serna and Alimi, they predict the observed primordial abundance of light elements for a very wide range of baryon density. These models are then consistent with recent CMB and Lyman-{alpha} estimates of the baryon content of the universe.

  10. Constant versus variable response signal delays in speed--accuracy trade-offs: effects of advance preparation for processing time.

    Science.gov (United States)

    Miller, Jeff; Sproesser, Gudrun; Ulrich, Rolf

    2008-07-01

    In two experiments, we used response signals (RSs) to control processing time and trace out speed--accuracy trade-off(SAT) functions in a difficult perceptual discrimination task. Each experiment compared performance in blocks of trials with constant and, hence, temporally predictable RS lags against performance in blocks with variable, unpredictable RS lags. In both experiments, essentially equivalent SAT functions were observed with constant and variable RS lags. We conclude that there is little effect of advance preparation for a given processing time, suggesting that the discrimination mechanisms underlying SAT functions are driven solely by bottom-up information processing in perceptual discrimination tasks.

  11. Turbulence modification in bubbly upward pipe flow. Extraction of time resolved turbulent microscopic structure by high speed PIV

    International Nuclear Information System (INIS)

    Yoshimura, Koki; Minato, Daiju; Sato, Yohei; Hishida, Koichi

    2004-01-01

    The objective of the present study is to obtain detailed information on the effects of bubbles on modification of turbulent structure by time-series measurements using a high speed time-resolved PIV. The experiments were carried out in a fully-developed vertical pipe with upflow of water at the Reynolds number of 9700 and the void fraction of 0.5%. It is observed that turbulence production was decreased and the dissipation rate was enhanced in the whole domain. We analyzed the effects of bubbles on modification of the energy cascade process from power spectra of velocity fluctuation of the continuous phase. (author)

  12. Gimbaled-shoulder friction stir welding tool

    Science.gov (United States)

    Carter, Robert W. (Inventor); Lawless, Kirby G. (Inventor)

    2010-01-01

    A gimbaled-shoulder friction stir welding tool includes a pin and first and second annular shoulders coupled to the pin. At least one of the annular shoulders is coupled to the pin for gimbaled motion with respect thereto as the tool is rotated by a friction stir welding apparatus.

  13. Orbital friction stir welding of aluminium pipes

    International Nuclear Information System (INIS)

    Engelhard, G.; Hillers, T.

    2002-01-01

    Friction stir welding (FSW) was originally developed for flat plates. This contribution shows how it can be applied to the welding of aluminium pipes. Pipes made of AlMG 3 (EN5754), AlMg 4.5Mn (EN5083) and AlMgSi 0.5 (EN6106) with dimensions of Da 600 and 520 x 10-8 mm were welded. The FSW orbital system comprises an annular cage with integrated FSW head, a hydraulic system, and a control unit. The welds were tested successfully according to EN 288. The mechanical and technical properties of the welds were somewhat better than with the TIG orbital process, and welding times were about 40 percent shorter [de

  14. Running speed during training and percent body fat predict race time in recreational male marathoners

    OpenAIRE

    Knechtle, Beat; Barandun,; Knechtle,Patrizia; Klipstein,; Rüst,Christoph Alexander; Rosemann,Thomas; Lepers,Romuald

    2012-01-01

     Background: Recent studies have shown that personal best marathon time is a strong predictor of race time in male ultramarathoners. We aimed to determine variables predictive of marathon race time in recreational male marathoners by using the same characteristics of anthropometry and training as used for ultramarathoners.Methods: Anthropometric and training characteristics of 126 recreational male marathoners were bivariately and multivariately related to marathon race times.Results...

  15. Introducing a new and rapid microextraction approach based on magnetic ionic liquids: Stir bar dispersive liquid microextraction.

    Science.gov (United States)

    Chisvert, Alberto; Benedé, Juan L; Anderson, Jared L; Pierson, Stephen A; Salvador, Amparo

    2017-08-29

    With the aim of contributing to the development and improvement of microextraction techniques, a novel approach combining the principles and advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) is presented. This new approach, termed stir bar dispersive liquid microextraction (SBDLME), involves the addition of a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar into the sample allowing the MIL coat the stir bar due to physical forces (i.e., magnetism). As long as the stirring rate is maintained at low speed, the MIL resists rotational (centrifugal) forces and remains on the stir bar surface in a manner closely resembling SBSE. By increasing the stirring rate, the rotational forces surpass the magnetic field and the MIL disperses into the sample solution in a similar manner to DLLME. After extraction, the stirring is stopped and the MIL returns to the stir bar without the requirement of an additional external magnetic field. The MIL-coated stir bar containing the preconcentrated analytes is thermally desorbed directly into a gas chromatographic system coupled to a mass spectrometric detector (TD-GC-MS). This novel approach opens new insights into the microextraction field, by using the benefits provided by SBSE and DLLME simultaneously, such as automated thermal desorption and high surface contact area, respectively, but most importantly, it enables the use of tailor-made solvents (i.e., MILs). To prove its utility, SBDLME has been used in the extraction of lipophilic organic UV filters from environmental water samples as model analytical application with excellent analytical features in terms of linearity, enrichment factors (67-791), limits of detection (low ng L -1 ), intra- and inter-day repeatability (RSD<15%) and relative recoveries (87-113%, 91-117% and 89-115% for river, sea and swimming pool water samples, respectively). Copyright © 2017 Elsevier B.V. All rights reserved.

  16. The Effect of Tool Pin Shape of Friction Stir Welding (FSW) on Polypropylene

    Science.gov (United States)

    Nik, Z. C.; Ishak, M.; Othman, N. H.

    2017-09-01

    This experiment deals with similar joining of polypropylene (PP) with thickness of 3 mm was carried out by using friction stir welding (FSW) technique. The process parameters, rotational speed, welding speed and tilt angle were fixed of experiments. The tool geometry shapes were the main parameters which were taken into consideration. The optimum designs of tool geometry shape were determined with reference to tensile strength of the joint. During the tensile testing experiment, the results show that all fractured occurs in the heat-affected zone (HAZ) on the polypropylene (PP). Results show that the optimum design can be obtained with same rotational speed, welding speed and tilt angle.

  17. Real-Time Vehicle Speed Estimation Based on License Plate Tracking in Monocular Video Sequences

    Directory of Open Access Journals (Sweden)

    Aleksej MAKAROV

    2016-02-01

    Full Text Available A method of estimating the vehicle speed from images obtained by a fixed over-the-road monocular camera is presented. The method is based on detecting and tracking vehicle license plates. The contrast between the license plate and its surroundings is enhanced using infrared light emitting diodes and infrared camera filters. A range of the license plate height values is assumed a priori. The camera vertical angle of view is measured prior to installation. The camera tilt is continuously measured by a micro-electromechanical sensor. The distance of the license plate from the camera is theoretically derived in terms of its pixel coordinates. Inaccuracies due to the frame rate drift, to the tilt and the angle of view measurement errors, to edge pixel detection and to a coarse assumption of the vehicle license plate height are analyzed and theoretically formulated. The resulting system is computationally efficient, inexpensive and easy to install and maintain along with the existing ALPR cameras.

  18. Atmospheric pressure gas chromatography–time-of-flight-mass spectrometry (APGC–ToF-MS) for the determination of regulated and emerging contaminants in aqueous samples after stir bar sorptive extraction (SBSE)

    International Nuclear Information System (INIS)

    Pintado-Herrera, Marina G.; González-Mazo, Eduardo; Lara-Martín, Pablo A.

    2014-01-01

    Graphical abstract: Examples of identification of target (triclosan, TCS) and non-target (tributhyl phosphate, TBP) compounds in environmental water samples by APGC–ToF-MS. Some confirmation criteria are shown (i.e. mass spectra, isotopic distribution, and accurate mass). - Highlights: • 102 regulated and emerging contaminants are simultaneously extracted by SBSE. • APGC–ToF-MS is presented as an alternative to EI for the analysis of microcontaminants. • Identification of non-target compounds in environmental matrices is also explored. - Abstract: This work presents the development, optimization and validation of a multi-residue method for the simultaneous determination of 102 contaminants, including fragrances, UV filters, repellents, endocrine disruptors, biocides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and several types of pesticides in aqueous matrices. Water samples were processed using stir bar sorptive extraction (SBSE) after the optimization of several parameters: agitation time, ionic strength, presence of organic modifiers, pH, and volume of the derivatizing agent. Target compounds were extracted from the bars by liquid desorption (LD). Separation, identification and quantification of analytes were carried out by gas chromatography (GC) coupled to time-of-flight (ToF-MS) mass spectrometry. A new ionization source, atmospheric pressure gas chromatography (APGC), was tested. The optimized protocol showed acceptable recovery percentages (50–100%) and limits of detection below 1 ng L −1 for most of the compounds. Occurrence of 21 out of 102 analytes was confirmed in several environmental aquatic matrices, including seawater, sewage effluent, river water and groundwater. Non-target compounds such as organophosphorus flame retardants were also identified in real samples by accurate mass measurement of their molecular ions using GC-APGC–ToF-MS. To the best of our knowledge, this is the first time that this

  19. Atmospheric pressure gas chromatography–time-of-flight-mass spectrometry (APGC–ToF-MS) for the determination of regulated and emerging contaminants in aqueous samples after stir bar sorptive extraction (SBSE)

    Energy Technology Data Exchange (ETDEWEB)

    Pintado-Herrera, Marina G.; González-Mazo, Eduardo; Lara-Martín, Pablo A., E-mail: pablo.lara@uca.es

    2014-12-03

    Graphical abstract: Examples of identification of target (triclosan, TCS) and non-target (tributhyl phosphate, TBP) compounds in environmental water samples by APGC–ToF-MS. Some confirmation criteria are shown (i.e. mass spectra, isotopic distribution, and accurate mass). - Highlights: • 102 regulated and emerging contaminants are simultaneously extracted by SBSE. • APGC–ToF-MS is presented as an alternative to EI for the analysis of microcontaminants. • Identification of non-target compounds in environmental matrices is also explored. - Abstract: This work presents the development, optimization and validation of a multi-residue method for the simultaneous determination of 102 contaminants, including fragrances, UV filters, repellents, endocrine disruptors, biocides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and several types of pesticides in aqueous matrices. Water samples were processed using stir bar sorptive extraction (SBSE) after the optimization of several parameters: agitation time, ionic strength, presence of organic modifiers, pH, and volume of the derivatizing agent. Target compounds were extracted from the bars by liquid desorption (LD). Separation, identification and quantification of analytes were carried out by gas chromatography (GC) coupled to time-of-flight (ToF-MS) mass spectrometry. A new ionization source, atmospheric pressure gas chromatography (APGC), was tested. The optimized protocol showed acceptable recovery percentages (50–100%) and limits of detection below 1 ng L{sup −1} for most of the compounds. Occurrence of 21 out of 102 analytes was confirmed in several environmental aquatic matrices, including seawater, sewage effluent, river water and groundwater. Non-target compounds such as organophosphorus flame retardants were also identified in real samples by accurate mass measurement of their molecular ions using GC-APGC–ToF-MS. To the best of our knowledge, this is the first time that this

  20. The role of the STIR sequence in magnetic resonance imaging examination of bone tumours

    International Nuclear Information System (INIS)

    Golfieri, R.; Baddeley, H.; Pringle, J.S.; Souhami, R.

    1990-01-01

    Sixty patients with primary bone tumours were evaluated with magnetic resonance imaging (MRI) at 0.5 T with both conventional spin-echo (SE) and short inversion time inversion recovery (STIR) sequences. The STIR sequence with T 1 of 120-130 ms in all cases suppressed the high signal from fatty bone marrow, giving a clear depiction of tumour extent, in both its intramedullary and soft-tissue components, and is superior to conventional SE images. The high sensitivity (100% of our cases) of this technique is counterbalanced by its lack of specificity: on STIR sequences both tumour and peritumorous oedema give an increase of signal intensity, limiting assessment of tumour extent. Peritumoral oedema, only present in this series in malignant neoplasms, may however be differentiated on the basis of the configuration of the abnormal areas, and by comparing STIR images with short repetition time/echo time sequence results. (author)

  1. Effect of prior warm-up duration on the time limit at peak speed in untrained men.

    Science.gov (United States)

    da Cruz, Victor H; Peserico, Cecília S; Machado, Fabiana A

    2017-10-01

    The peak speed (Vpeak) and its time limit (tlim) are variables used to prescribe training loads and the intervals durations during interval training, respectively. The aim of this study was to test different warm-up durations (5, 10 and 15 minutes), adapted from the protocol proposed by Billat et al.,1 to determine tlim in untrained men. Fifteen untrained men were submitted to the following laboratory evaluations: 1) an incremental running exercise test on a treadmill starting with a speed of 8 km/h, after a warm-up of walking at 6 km/h for three minutes, and increased by 1 km/h between each successive 3-minute stage until volitional exhaustion to determine Vpeak; 2) three rectangular tests, performed in randomized order, with warm-up durations of 5, 10, and 15 minutes at 60% of Vpeak to determine the tlim5, tlim10, and tlim15; after the warm-up the tests were performed at the speed of the individual Vpeak until volitional exhaustion. It was demonstrated that the duration of the warm-up affected the test duration (tlim). Significant differences were observed between tlim5 and tlim15, and between tlim10 and tlim15. However, tlim15 and tlim10 did not differ. Additionally, duration of the warm-up did not influence other variables (HRmax, RPEmax and post lactate concentrations). Therefore, it was concluded that the duration of the warm-up in tlim tests modifies the test duration in untrained men.

  2. Path integration of head direction: updating a packet of neural activity at the correct speed using neuronal time constants.

    Science.gov (United States)

    Walters, D M; Stringer, S M

    2010-07-01

    A key question in understanding the neural basis of path integration is how individual, spatially responsive, neurons may self-organize into networks that can, through learning, integrate velocity signals to update a continuous representation of location within an environment. It is of vital importance that this internal representation of position is updated at the correct speed, and in real time, to accurately reflect the motion of the animal. In this article, we present a biologically plausible model of velocity path integration of head direction that can solve this problem using neuronal time constants to effect natural time delays, over which associations can be learned through associative Hebbian learning rules. The model comprises a linked continuous attractor network and competitive network. In simulation, we show that the same model is able to learn two different speeds of rotation when implemented with two different values for the time constant, and without the need to alter any other model parameters. The proposed model could be extended to path integration of place in the environment, and path integration of spatial view.

  3. Microstructural and mechanical properties of pure aluminum, 5083 and 7075 alloys joined by friction stir welding

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, Selim Sarper [Celal Bayar Univ., Manisa, Muradiye (Turkey)

    2012-07-01

    In this study, microstructural and mechanical properties of pure aluminum, 5083 and 7075 alloys joined by friction stir welding were investigated. Hardness, tensile, bending and impact tests were applied to the welded samples. In addition, optical and SEM tests were carried out. The effects of welding speed on microstructure and mechanical properties were investigated in these materials. Then, the optimal conditions for friction stir welding were determined for pure aluminum, 5083 and 7075 alloys. The maximum hardness was observed for 7075 while the minimum hardness was observed for pure aluminum. (orig.)

  4. Effect of two-qutrit entanglement on quantum speed limit time of a bipartite V-type open system

    Energy Technology Data Exchange (ETDEWEB)

    Behzadi, N., E-mail: n.behzadi@tabrizu.ac.ir [Research Institute for Fundamental Sciences, University of Tabriz (Iran, Islamic Republic of); Ahansaz, B.; Ektesabi, A.; Faizi, E. [Physics Department, Azarbaijan Shahid Madani University, Tabriz (Iran, Islamic Republic of)

    2017-03-15

    In the present paper, quantum speed limit (QSL) time of a bipartite V-type three-level atomic system under the effect of two-qutrit entanglement is investigated. Each party interacts with own independent reservoir. By considering two local unitarily equivalent Werner states and the Horodecki PPT state, as initial states, the QSL time is evaluated for each of them in the respective entangled regions. It is counterintuitively observed that the effect of entanglement on the QSL time driven from each of the initial Werner states are completely different when the degree of non-Markovianity is considerable. In addition, it is interesting that the effect of entanglement of the non-equivalent Horodecki state on the calculated QSL time displays an intermediate behavior relative to the cases obtained for the Werner states.

  5. Click trains and the rate of information processing: does "speeding up" subjective time make other psychological processes run faster?

    Science.gov (United States)

    Jones, Luke A; Allely, Clare S; Wearden, John H

    2011-02-01

    A series of experiments demonstrated that a 5-s train of clicks that have been shown in previous studies to increase the subjective duration of tones they precede (in a manner consistent with "speeding up" timing processes) could also have an effect on information-processing rate. Experiments used studies of simple and choice reaction time (Experiment 1), or mental arithmetic (Experiment 2). In general, preceding trials by clicks made response times significantly shorter than those for trials without clicks, but white noise had no effects on response times. Experiments 3 and 4 investigated the effects of clicks on performance on memory tasks, using variants of two classic experiments of cognitive psychology: Sperling's (1960) iconic memory task and Loftus, Johnson, and Shimamura's (1985) iconic masking task. In both experiments participants were able to recall or recognize significantly more information from stimuli preceded by clicks than those preceded by silence.

  6. Time and speed of fruit drying on batch fluid-beds

    Indian Academy of Sciences (India)

    physical, chemical and nutritional characteristics of food materials and products and their ... Depending on the pretreatment applied, rehydration times are up to 30% faster and the ..... time (X), the value approaches the equilibrium moisture content. .... Perry R H, Green D W 1997Perry's chemical engineer's handbook7th edn ...

  7. Friction Stir Welding (FSW) of Aged CuCrZr Alloy Plates

    Science.gov (United States)

    Jha, Kaushal; Kumar, Santosh; Nachiket, K.; Bhanumurthy, K.; Dey, G. K.

    2018-01-01

    Friction Stir Welding (FSW) of Cu-0.80Cr-0.10Zr (in wt pct) alloy under aged condition was performed to study the effects of process parameters on microstructure and properties of the joint. FSW was performed over a wide range of process parameters, like tool-rotation speed (from 800 to 1200 rpm) and tool-travel speed (from 40 to 100 mm/min), and the resulting thermal cycles were recorded on both sides (advancing and retreating) of the joint. The joints were characterized for their microstructure and tensile properties. The welding process resulted in a sound and defect-free weld joint, over the entire range of the process parameters used in this study. Microstructure of the stir zone showed fine and equiaxed grains, the scale of which varied with FSW process parameters. Grain size in the stir zone showed direct correlation with tool rotation and inverse correlation with tool-travel speed. Tensile strength of the weld joints was ranging from 225 to 260 MPa, which is substantially lower than that of the parent metal under aged condition ( 400 MPa), but superior to that of the parent material under annealed condition ( 220 MPa). Lower strength of the FSW joint than that of the parent material under aged condition can be attributed to dissolution of the precipitates in the stir zone and TMAZ. These results are presented and discussed in this paper.

  8. Retractable Pin Tools for the Friction Stir Welding Process

    Science.gov (United States)

    1998-01-01

    Two companies have successfully commercialized a specialized welding tool developed at the Marshall Space Flight Center (MSFC). Friction stir welding uses the high rotational speed of a tool and the resulting frictional heat created from contact to crush, 'stir' together, and forge a bond between two metal alloys. It has had a major drawback, reliance on a single-piece pin tool. The pin is slowly plunged into the joint between two materials to be welded and rotated as high speed. At the end of the weld, the single-piece pin tool is retracted and leaves a 'keyhole,' something which is unacceptable when welding cylindrical objects such as drums, pipes and storage tanks. Another drawback is the requirement for different-length pin tools when welding materials of varying thickness. An engineer at the MSFC helped design an automatic retractable pin tool that uses a computer-controlled motor to automatically retract the pin into the shoulder of the tool at the end of the weld, preventing keyholes. This design allows the pin angle and length to be adjusted for changes in material thickness and results in a smooth hole closure at the end of the weld. Benefits of friction stir welding, using the MSFC retractable pin tool technology, include the following: The ability to weld a wide range of alloys, including previously unweldable and composite materials; provision of twice the fatigue resistance of fusion welds and no keyholes; minimization of material distortion; no creation of hazards such as welding fumes, radiation, high voltage, liquid metals, or arcing; automatic retraction of the pin at the end of the weld; and maintaining full penetration of the pin.

  9. Effect of tool shape and welding parameters on mechanical properties and microstructure of dissimilar friction stir welded aluminium alloys

    Directory of Open Access Journals (Sweden)

    Chetan Aneja

    2016-07-01

    Full Text Available In the present experimental study, dissimilar aluminum alloy AA5083 and AA6082 were friction stir welded by varying tool shape, welding speed and rotary speed of the tool in order to investigate the effect of varying tool shape and welding parameters on the mechanical properties as well as microstructure. The friction stir welding (FSW process parameters have great influence on heat input per unit length of weld. The outcomes of experimental study prove that mechanical properties increases with decreasing welding speed. Furthermore mechanical properties were also found to improve as the rotary speed increases and the same phenomenon was found to happen while using straight cylindrical threaded pin profile tool. The microstructure of the dissimilar joints revealed that at low welding speeds, the improved material mixing was observed. The similar phenomenon was found to happen at higher rotational speeds using straight cylindrical threaded tool.

  10. Selection of TI for Suppression Fat Tissue of SPAIR and Comparative Study of SPAIR and STIR of Brain Fast SE T2 Weighted Imaging

    International Nuclear Information System (INIS)

    Lee, Hoo Min; Kim, Ham Gyum; Kong, Seok Kyo

    2009-01-01

    The purpose of this research is to seek SPAIR's reversal time (TI) which satisfies two conditions ; maintaining the suppression ability of fat tissue and simultaneously minimizing the inhomogeneity of fat tissue in T2 high-speed spin echo 3.0T magnetic resonance image (MRI) of the brain, and to compare SPAIR with STIR which is fat-suppression technique. The reversal times (TI) of SPAIR protocol are set to 1/2, 1/3, 1/6 and 1/12 of SPAIR TR (420 msec), namely 210 msec (8 people), 140 msec (26 people), 70 msec (26 people) and 35 msec (18 people) and STIR TI is set with 250 msec (26 people). With these parameter sets, we acquired the axis direction 104 images of the brain. In ROI (50 mm 2 ) of output image, signal intensities of the fatty tissue, the muscular tissue, and the background were measured and the CNRs of fatty tissue and the muscular tissue were calculated. The inhomogeneity of the fatty tissue is SD/mean, where SD is the standard deviation and 'mean' is a average fatty tissue signal. Consequently, SPAIR TI is determined on either 1/3 or 1/6 of TR (420 ms) ; 140 ms or 70 ms. Because the difference of statistics in fat-suppression ability and inhomogeneity of fatty tissue is very small (p < 0.001), Selecting 140 ms seems to be better choice for the image quality. Meanwhile, Comparing SPAIR (TI : 140 ms) with STIR, the fat-suppression is not able to be considered statistically (p < 0.252), but the image quality is able to be considered statistically (p < 0.01). In conclusion, SPAIR is better than STIR in the image quality.

  11. Incorporating geostrophic wind information for improved space–time short-term wind speed forecasting

    KAUST Repository

    Zhu, Xinxin; Bowman, Kenneth P.; Genton, Marc G.

    2014-01-01

    pressure, temperature, and other meteorological variables, no improvement in forecasting accuracy was found by incorporating air pressure and temperature directly into an advanced space-time statistical forecasting model, the trigonometric direction diurnal

  12. Speed and Duration of Walking and Other Leisure Time Physical Activity and the Risk of Heart Failure

    DEFF Research Database (Denmark)

    Sævereid, Hans Askelund; Schnohr, Peter; Prescott, Eva

    2014-01-01

    in 1976-2003, we studied the association between updated self-assessed leisure-time PA, speed and duration of walking and subsequent hospitalization or death from HF. Light and moderate/high level of leisure-time PA and brisk walking were associated with reduced risk of HF in both genders whereas...... no consistent association with duration of walking was seen. In 18,209 subjects age 20-80 with 1580 cases of HF, using the lowest activity level as reference, the confounder-adjusted hazard ratios (HR) for light and moderate/high leisure-time physical activity were 0.75 (0.66-0.86) and 0.80 (0......-spread PA and public health measures to curb the increase in HF may benefit from this information....

  13. Reducing 4DCBCT imaging time and dose: the first implementation of variable gantry speed 4DCBCT on a linear accelerator.

    Science.gov (United States)

    O'Brien, Ricky T; Stankovic, Uros; Sonke, Jan-Jakob; Keall, Paul J

    2017-06-07

    Four dimensional cone beam computed tomography (4DCBCT) uses a constant gantry speed and imaging frequency that are independent of the patient's breathing rate. Using a technique called respiratory motion guided 4DCBCT (RMG-4DCBCT), we have previously demonstrated that by varying the gantry speed and imaging frequency, in response to changes in the patient's real-time respiratory signal, the imaging dose can be reduced by 50-70%. RMG-4DCBCT optimally computes a patient specific gantry trajectory to eliminate streaking artefacts and projection clustering that is inherent in 4DCBCT imaging. The gantry trajectory is continuously updated as projection data is acquired and the patient's breathing changes. The aim of this study was to realise RMG-4DCBCT for the first time on a linear accelerator. To change the gantry speed in real-time a potentiometer under microcontroller control was used to adjust the current supplied to an Elekta Synergy's gantry motor. A real-time feedback loop was developed on the microcontroller to modulate the gantry speed and projection acquisition in response to the real-time respiratory signal so that either 40, RMG-4DCBCT 40 , or 60, RMG-4DCBCT 60 , uniformly spaced projections were acquired in 10 phase bins. Images of the CIRS dynamic Thorax phantom were acquired with sinusoidal breathing periods ranging from 2 s to 8 s together with two breathing traces from lung cancer patients. Image quality was assessed using the contrast to noise ratio (CNR) and edge response width (ERW). For the average patient, with a 3.8 s breathing period, the imaging time and image dose were reduced by 37% and 70% respectively. Across all respiratory rates, RMG-4DCBCT 40 had a CNR in the range of 6.5 to 7.5, and RMG-4DCBCT 60 had a CNR between 8.7 and 9.7, indicating that RMG-4DCBCT allows consistent and controllable CNR. In comparison, the CNR for conventional 4DCBCT drops from 20.4 to 6.2 as the breathing rate increases from 2 s to 8 s. With RMG-4DCBCT

  14. Friction Stir Welding and Processing

    Energy Technology Data Exchange (ETDEWEB)

    Hovanski, Yuri; Carsley, John; Clarke, Kester D.; Krajewski, Paul E.

    2015-05-01

    With nearly twenty years of international research and collaboration in friction stir welding (FSW) and processing industrial applications have spread into nearly every feasible market. Currently applications exist in aerospace, railway, automotive, personal computers, technology, marine, cutlery, construction, as well as several other markets. Implementation of FSW has demonstrated diverse opportunities ranging from enabling new materials to reducing the production costs of current welding technologies by enabling condensed packaging solutions for traditional fabrication and assembly. TMS has sponsored focused instruction and communication in this technology area for more than fifteen years, with leadership from the Shaping and Forming Committee, which organizes a biannual symposium each odd year at the annual meeting. A focused publication produced from each of these symposia now comprises eight volumes detailing the primary research and development activities in this area over the last two decades. The articles assembled herein focus on both recent developments and technology reviews of several key markets from international experts in this area.

  15. High-speed real-time OFDM transmission based on FPGA

    Science.gov (United States)

    Xiao, Xin; Li, Fan; Yu, Jianjun

    2016-02-01

    In this paper, we review our recent research progresses on real-time orthogonal frequency division multiplexing (OFDM) transmission based on FPGA. We successfully demonstrated four-channel wavelength-division multiplexing (WDM) 256.51Gb/s 16-ary quadrature amplitude modulation (16QAM)-OFDM signal transmission system for short-reach optical amplifier free inter-connection with real-time reception. Four optical carriers are modulated by four different 16QAM-OFDM signals via 10G-class direct modulation lasers (DMLs). We achieved highest capacity real-time reception optical OFDM signal transmission over 2.4-km SMF with the bit-error ratio (BER) under soft-decision forward error correction (SD-FEC) limitation of 2.4×10-2. In order to achieve higher spectrum efficiency (SE), we demonstrate 4-channel high level QAM-OFDM transmission over 20-km SMF-28 with real-time reception. 58.72-Gb/s 256QAM-OFDM and 56.4-Gb/s 128QAM-OFDM signal transmission within 25-GHz grid is achieved with the BER under 2.4×10-2 and real-time reception.

  16. System architecture for high speed reconstruction in time-of-flight positron tomography

    International Nuclear Information System (INIS)

    Campagnolo, R.E.; Bouvier, A.; Chabanas, L.; Robert, C.

    1985-06-01

    A new generation of Time Of Flight (TOF) positron tomograph with high resolution and high count rate capabilities is under development in our group. After a short recall of the data acquisition process and image reconstruction in a TOF PET camera, we present the data acquisition system which achieves a data transfer rate of 0.8 mega events per second or more if necessary in list mode. We describe the reconstruction process based on a five stages pipe line architecture using home made processors. The expected performance with this architecture is a time reconstruction of six seconds per image (256x256 pixels) of one million events. This time could be reduce to 4 seconds. We conclude with the future developments of the system

  17. Prolegomena to the Study of Friction Stir Welding

    Science.gov (United States)

    Nunes, Arthur C., Jr.

    2010-01-01

    The literature contains many approaches toward modeling of the friction stir welding (FSW) process with varying treatments of the weld metal properties. It is worthwhile to consider certain fundamental features of the process before attempting to interpret FSW phenomena: Because of the unique character of metal deformation (as opposed to, say, viscous deformation) a velocity "discontinuity" or shear surface occurs in FSW and determines much of the character of the welding mechanism. A shear surface may not always produce a sound bond. Balancing mechanical power input against conduction and convection heat losses yields a relation, a "temperature index", between spindle speed and travel speed to maintain constant weld temperature. But many process features are only weakly dependent upon temperature. Thus, unlike modeling of metal forming processes, it may be that modeling the FSW process independently of the material conditions has some merit.

  18. Micro friction stir welding of copper electrical contacts

    Directory of Open Access Journals (Sweden)

    D. Klobčar

    2014-10-01

    Full Text Available The paper presents an analysis of micro friction stir welding (μFSW of electrolytic tough pitch copper (CuETP in a lap and butt joint. Experimental plan was done in order to investigate the influence of tool design and welding parameters on the formation of defect free joints. The experiments were done using universal milling machine where the tool rotation speed varied between 600 and 1 900 rpm, welding speed between 14 and 93 mm/min and tilt angle between 3° and 5°. From the welds samples for analysis of microstructure and samples for tensile tests were prepared. The grain size in the nugget zone was greatly reduced compared to the base metal and the joint tensile strength exceeded the strength of the base metal.

  19. Friction stir welding (FSW process of copper alloys

    Directory of Open Access Journals (Sweden)

    M. Miličić

    2016-01-01

    Full Text Available The present paper analyzes the structure of the weld joint of technically pure copper, which is realized using friction stir welding (FSW. The mechanism of thermo-mechanical processes of the FSW method has been identified and a correlation between the weld zone and its microstructure established. Parameters of the FSW welding technology influencing the zone of the seam material and the mechanical properties of the resulting joint were analyzed. The physical joining consists of intense mixing the base material along the joint line in the “doughy” phase. Substantial plastic deformations immediately beneath the frontal surface of tool provide fine-grained structure and a good quality joint. The optimum shape of the tool and the optimum welding regime (pressure force, rotation speed and the traverse speed of the tool in the heat affected zone enable the achievement of the same mechanical properties as those of the basic material, which justifies its use in welding reliable structures.

  20. Real-Time Order Tracking of Gear Mesh Vibration in High Speed Planetary Gearboxes

    Directory of Open Access Journals (Sweden)

    Plöger Daniel Fritz

    2018-01-01

    Full Text Available Possible approaches to real-time order tracking are discussed. Two methods for real-time order tracking are developed and validated experimentally for the entire audible spectrum. An adaptive heterodyne filter bank is compared to a direct integral transform. The performance of both methods is adequate for usage in an active vibration control (AVC algorithm. Vold-Kalman filters are not suitable for AVC. The vibration data of three different planetary gearboxes is analyzed using order tracking. While some of the existing research could be reproduced, the data contradicts statements made by several authors. Lastly, the architecture of a novel AVC algorithm is sketched out.

  1. Rotation stability of high speed neutron time-of-flight mechanical chopper

    International Nuclear Information System (INIS)

    Habib, N.; Adib, M.

    1998-01-01

    A modified rotation stabilization system has been designed to maintain the stability of a neutron time-of-flight (TOF) mechanical chopper rates from 460 rpm to 16000 rpm. The main principle of the system is based on comparing the chopper's rotation period with the preselected one from a quartz timer. The result of comparison is used to control the current driver of the chopper's motor. A 600 Hz three phase generator controlled by a magnetic amplifier was used as a current driver. The stability of the chopper's rotation rate at 16000 rpm was 0.02%. An improved method precise time scale calibration of the TOF spectrometer is applied

  2. Speeding up development activities in student projects with time boxing and scrum

    DEFF Research Database (Denmark)

    Ovesen, Nis; Eriksen, Kaare; Tollestrup, Christian

    2011-01-01

    This research project investigates how procedures from agile software development can be of benefit to development activities in projects of design engineering students. The agile methods Scrum and Time boxing are evaluated through a student workshop focusing on near-future concepts for design...... competitions. Scrum meetings within the student design teams are conducted and video documented each hour throughout the workshop activities as a structured process evaluation tool. Based on a subsequent student survey it is argued that scrum and time boxing are strengthening the focus, communication...

  3. Microstructure examination and microhardness of friction stir welded joint of (AA7020-O after PWHT

    Directory of Open Access Journals (Sweden)

    Ghada M.F. Essa

    2018-04-01

    Full Text Available This paper studies the microstructure and microhardness of the welded joints of the annealed aluminum alloy AA7020-O produced by friction stir welding (FSW technique. The material was applied to post weld heat treatment (solution treatment and artificially aged, T6. The traverse speed and the rotational speed are the most important process parameters of FSW, and have great influence on the heat input of the welding operation which governs the welded joints quality. To investigate their effect, the welding operation was performed using three traverse speeds, 20, 40 and 60 mm/s with two rotational speeds of 1125 and 1400 rpm, and other welding parameters were kept constant to produce comparable joints. It was found that the two rotational speeds are accepted with lower traverse speeds to produce sound joints. Microstructure of the welded joints was significantly affected by the FSW process parameters, and slight effect was reported for the grain size. Microhardness examination showed high weld joint quality with respect to the base metal hardness, which proves the reprecipitation of the hardening phase in the weld zone. The microhardness profile was strongly dependant on the rotational speed, and the average values of the joints hardness have increased with the decrease in the rotational speed, where it have been slightly affected by the welding speed. Keywords: Friction stir welding, Aluminum alloy, Mechanical properties, Microstructures

  4. Physics-based process model approach for detecting discontinuity during friction stir welding

    Energy Technology Data Exchange (ETDEWEB)

    Shrivastava, Amber; Pfefferkorn, Frank E.; Duffie, Neil A.; Ferrier, Nicola J.; Smith, Christopher B.; Malukhin, Kostya; Zinn, Michael

    2015-02-12

    The goal of this work is to develop a method for detecting the creation of discontinuities during friction stir welding. This in situ weld monitoring method could significantly reduce the need for post-process inspection. A process force model and a discontinuity force model were created based on the state-of-the-art understanding of flow around an friction stir welding (FSW) tool. These models are used to predict the FSW forces and size of discontinuities formed in the weld. Friction stir welds with discontinuities and welds without discontinuities were created, and the differences in force dynamics were observed. In this paper, discontinuities were generated by reducing the tool rotation frequency and increasing the tool traverse speed in order to create "cold" welds. Experimental force data for welds with discontinuities and welds without discontinuities compared favorably with the predicted forces. The model currently overpredicts the discontinuity size.

  5. Friction Stir Welding of Dissimilar Al/Al and Al/Non-Al Alloys: A Review

    Science.gov (United States)

    Wang, Xiangbin; Pan, Yi; Lados, Diana A.

    2018-05-01

    Friction stir welding is a solid-state welding technique that has many advantages over traditional fusion welding, and has been widely adopted in the aerospace and automotive industries. This article reviews research developments in friction stir welding of dissimilar alloys systems, including combinations of aluminum alloys with Mg alloys, Cu, and steel. Microstructural evolution, hardness, tensile and fatigue properties, residual stresses, and corrosion behavior of dissimilar welds will be reported. The effects of processing parameters such as tool rotation and traverse speeds, tool position, material position, and tool geometry on the weld quality are also presented. Discussions on future research directions in friction stir welding will also be provided in the context of existing literature and future high-integrity applications.

  6. Speeding up : new Atlas Copco rig meant to cut non-drilling time

    Energy Technology Data Exchange (ETDEWEB)

    Roche, P.

    2009-06-15

    Automation has significantly reduced the time needed to drill shallow to medium-depth wells. The time it takes for a drill to reach the production zone is decreasing because newly developed hydraulic systems are able to maintain a constant pace. However, a great deal of time is still consumed by demobilization, transportation and setting up to drill the next well. Atlas Copco Drilling Solutions, a Swedish-based global maker of industrial equipment such as mining and mineral exploration rigs, designed a new Predator drilling system that consists of a mobile rig, a substructure and a pipe-handling skate. The Predator drilling system reduces non-drilling time and the associated costs. This article described the design of this new drilling system with particular reference to how it combines the mobile rig, the substructure and the pipe-handling skate into a three-load package. In order to reduce rig weight and improve mobility, the system is designed so that the table, master bushing, hydraulic slips and iron roughneck are part of the substructure that travel together. The rig has a working hook load capacity of 200,000 pounds, translating into a nominal depth capacity of 8,000 to 10,000 feet. The article also described the mounting of the rig, maneuverability, hydraulic control, and pipe-handling safety. Its various components were also described. 1 ref., 1 fig.

  7. Time and speed of fruit drying on batch fluid-beds

    Indian Academy of Sciences (India)

    Drying of particles (pieces) in a fluidized bed affords better quality of end products, especially for better product structure and its shorter reconstitution time. Fluid-bed drying of different fruit particles has been investigated. Starting water content varies from grape berries 81·5% and peach 87·7% to apricot 86·9%.

  8. A large capacity time division multiplexed (TDM) laser beam combining technique enabled by nanosecond speed KTN deflector

    Science.gov (United States)

    Yin, Stuart (Shizhuo); Chao, Ju-Hung; Zhu, Wenbin; Chen, Chang-Jiang; Campbell, Adrian; Henry, Michael; Dubinskiy, Mark; Hoffman, Robert C.

    2017-08-01

    In this paper, we present a novel large capacity (a 1000+ channel) time division multiplexing (TDM) laser beam combining technique by harnessing a state-of-the-art nanosecond speed potassium tantalate niobate (KTN) electro-optic (EO) beam deflector as the time division multiplexer. The major advantages of TDM approach are: (1) large multiplexing capability (over 1000 channels), (2) high spatial beam quality (the combined beam has the same spatial profile as the individual beam), (3) high spectral beam quality (the combined beam has the same spectral width as the individual beam, and (4) insensitive to the phase fluctuation of individual laser because of the nature of the incoherent beam combining. The quantitative analyses show that it is possible to achieve over one hundred kW average power, single aperture, single transverse mode solid state and/or fiber laser by pursuing this innovative beam combining method, which represents a major technical advance in the field of high energy lasers. Such kind of 100+ kW average power diffraction limited beam quality lasers can play an important role in a variety of applications such as laser directed energy weapons (DEW) and large-capacity high-speed laser manufacturing, including cutting, welding, and printing.

  9. Simulation of aluminium STIR casting technique

    International Nuclear Information System (INIS)

    Hafizal Yazid; Mohd Harun; Hanani Yazid; Abd Aziz Mohamed; Muhammad Rawi Muhammad Zain; Zaiton Selamat; Mohd Shariff Sattar; Muhamad Jalil; Ismail Mustapha; Razali Kasim

    2006-01-01

    In this paper, the objective is to determine the optimum impeller speed correlated with holding time to achieve homogeneous reinforcement distribution for a particular set of experimental condition. Attempts are made to simulate the flow behaviourof the liquid aluminium using FLUENT software. Stepwise impeller speed ranging from 50 to 300 rpm.with 2 impeller angle blades of 45 and 90 degree with respect to the rotational plane were used

  10. Development of high speed integrated circuit for very high resolution timing measurements

    International Nuclear Information System (INIS)

    Mester, Christian

    2009-10-01

    A multi-channel high-precision low-power time-to-digital converter application specific integrated circuit for high energy physics applications has been designed and implemented in a 130 nm CMOS process. To reach a target resolution of 24.4 ps, a novel delay element has been conceived. This nominal resolution has been experimentally verified with a prototype, with a minimum resolution of 19 ps. To further improve the resolution, a new interpolation scheme has been described. The ASIC has been designed to use a reference clock with the LHC bunch crossing frequency of 40 MHz and generate all required timing signals internally, to ease to use within the framework of an LHC upgrade. Special care has been taken to minimise the power consumption. (orig.)

  11. Development of high speed integrated circuit for very high resolution timing measurements

    Energy Technology Data Exchange (ETDEWEB)

    Mester, Christian

    2009-10-15

    A multi-channel high-precision low-power time-to-digital converter application specific integrated circuit for high energy physics applications has been designed and implemented in a 130 nm CMOS process. To reach a target resolution of 24.4 ps, a novel delay element has been conceived. This nominal resolution has been experimentally verified with a prototype, with a minimum resolution of 19 ps. To further improve the resolution, a new interpolation scheme has been described. The ASIC has been designed to use a reference clock with the LHC bunch crossing frequency of 40 MHz and generate all required timing signals internally, to ease to use within the framework of an LHC upgrade. Special care has been taken to minimise the power consumption. (orig.)

  12. Clustering Gene Expression Time Series with Coregionalization: Speed propagation of ALS

    OpenAIRE

    Rahman, Muhammad Arifur; Heath, Paul R.; Lawrence, Neil D.

    2018-01-01

    Clustering of gene expression time series gives insight into which genes may be coregulated, allowing us to discern the activity of pathways in a given microarray experiment. Of particular interest is how a given group of genes varies with different model conditions or genetic background. Amyotrophic lateral sclerosis (ALS), an irreversible diverse neurodegenerative disorder showed consistent phenotypic differences and the disease progression is heterogeneous with significant variability. Thi...

  13. PET System Synchronization and Timing Resolution Using High-Speed Data Links

    OpenAIRE

    Aliaga Varea, Ramón José; Monzó Ferrer, José María; SPAGGIARI, MICHELE; Ferrando Jódar, Néstor; Gadea Gironés, Rafael; Colom Palero, Ricardo José

    2011-01-01

    Current PET systems with fully digital trigger rely on early digitization of detector signals and the use of digital processors, usually FPGAs, for recognition of valid gamma events on single detectors. Timestamps are assigned and later used for coincidence analysis. In order to maintain a decent timing resolution for events detected on different acquisition boards, it is necessary that local timestamps on different FPGAs be synchronized. Sub-nanosecond accuracy is mandatory if we want this e...

  14. Energy Savings by Wireless Control of Speed, Scheduling and Travel Times for Hauling Operation

    OpenAIRE

    Rylander, David; Axelsson, Jakob; Wallin, Peter

    2014-01-01

    A Quarry and Aggregate production site consist of sequential production processes and activities to process and produce the output products. Compared to a fixed manufacturing plant, the quarry processes involve mobile machines such as wheel loaders, trucks and articulated haulers and a highly dynamic road infrastructure. Today, the mobile machines are generally not synchronized or controlled towards the overall throughput of the site in real time. This indicates a general improvement potentia...

  15. Optimisation of process parameters in friction stir welding based on residual stress analysis: a feasibility study

    DEFF Research Database (Denmark)

    Tutum, Cem Celal; Hattel, Jesper Henri

    2010-01-01

    The present paper considers the optimisation of process parameters in friction stir welding (FSW). More specifically, the choices of rotational speed and traverse welding speed have been investigated using genetic algorithms. The welding process is simulated in a transient, two......-dimensional sequentially coupled thermomechanical model in ANSYS. This model is then used in an optimisation case where the two objectives are the minimisation of the peak residual stresses and the maximisation of the welding speed. The results indicate that the objectives for the considered case are conflicting......, and this is presented as a Pareto optimal front. Moreover, a higher welding speed for a fixed rotational speed results, in general, in slightly higher stress levels in the tension zone, whereas a higher rotational speed for a fixed welding speed yields somewhat lower peak residual stress, however, a wider tension zone...

  16. Kinetics of propionate conversion in anaerobic continuously stirred tank reactors

    DEFF Research Database (Denmark)

    Bangsø Nielsen, Henrik; Mladenovska, Zuzana; Ahring, Birgitte Kiær

    2008-01-01

    The kinetic parameters of anaerobic propionate degradation by biomass from 7 continuously stirred tank reactors differing in temperature, hydraulic retention time and substrate composition were investigated. In substrate-depletion experiments (batch) the maximum propionate degradation rate, A......-m, was estimated. The results demonstrate that the rate of endogenous substrate (propionate) production should be taken into account when estimating kinetic parameters in biomass from manure-based anaerobic reactors....

  17. Chemical reactions in the presence of surface modulation and stirring

    OpenAIRE

    Kamhawi, Khalid; Náraigh, Lennon Ó

    2009-01-01

    We study the dynamics of simple reactions where the chemical species are confined on a general, time-modulated surface, and subjected to externally-imposed stirring. The study of these inhomogeneous effects requires a model based on a reaction-advection-diffusion equation, which we derive. We use homogenization methods to show that up to second order in a small scaling parameter, the modulation effects on the concentration field are asymptotically equivalent for systems with or without stirri...

  18. Optic nerve injury demonstrated by MRI with STIR sequences

    International Nuclear Information System (INIS)

    Takehara, S.; Tanaka, T.; Uemura, K.; Shinohara, Y.; Yamamoto, T.; Tokuyama, T.; Satoh, A.

    1994-01-01

    We studied nine patients with optic nerve injury associated with closed head trauma by magnetic resonance imaging (MRI) with short inversion time inversion recovery (STIR) sequences on 11 occasions from 4 days to 14 years after the injury: three studies were within 17 days and eight over 4 months to 14 years. MRI revealed abnormal high signal in 10 of the 11 injured nerves. MRI 4 days after the injury showed no abnormality. (orig.)

  19. A Low-Power High-Speed Spintronics-Based Neuromorphic Computing System Using Real Time Tracking Method

    DEFF Research Database (Denmark)

    Farkhani, Hooman; Tohidi, Mohammad; Farkhani, Sadaf

    2018-01-01

    In spintronic-based neuromorphic computing systems (NCS), the switching of magnetic moment in a magnetic tunnel junction (MTJ) is used to mimic neuron firing. However, the stochastic switching behavior of the MTJ and process variations effect lead to a significant increase in stimulation time...... of such NCSs. Moreover, current NCSs need an extra phase to read the MTJ state after stimulation which is in contrast with real neuron functionality in human body. In this paper, the read circuit is replaced with a proposed real-time sensing (RTS) circuit. The RTS circuit tracks the MTJ state during...... stimulation phase. As soon as switching happens, the RTS circuit terminates the MTJ current and stimulates the post neuron. Hence, the RTS circuit not only improves the energy consumption and speed, but also makes the operation of NCS similar to real neuron functionality. The simulation results in 65-nm CMOS...

  20. Effects of fourth-order dispersion in very high-speed optical time-division multiplexed transmission.

    Science.gov (United States)

    Capmany, J; Pastor, D; Sales, S; Ortega, B

    2002-06-01

    We present a closed-form expression for computation of the output pulse's rms time width in an optical fiber link with up to fourth-order dispersion (FOD) by use of an optical source with arbitrary linewidth and chirp parameters. We then specialize the expression to analyze the effect of FOD on the transmission of very high-speed linear optical time-division multiplexing systems. By suitable source chirping, FOD can be compensated for to an upper link-length limit above which other techniques must be employed. Finally, a design formula to estimate the maximum attainable bit rate limited by FOD as a function of the link length is also presented.

  1. Real-time high-speed motion blur compensation system based on back-and-forth motion control of galvanometer mirror.

    Science.gov (United States)

    Hayakawa, Tomohiko; Watanabe, Takanoshin; Ishikawa, Masatoshi

    2015-12-14

    We developed a novel real-time motion blur compensation system for the blur caused by high-speed one-dimensional motion between a camera and a target. The system consists of a galvanometer mirror and a high-speed color camera, without the need for any additional sensors. We controlled the galvanometer mirror with continuous back-and-forth oscillating motion synchronized to a high-speed camera. The angular speed of the mirror is given in real time within 10 ms based on the concept of background tracking and rapid raw Bayer block matching. Experiments demonstrated that our system captures motion-invariant images of objects moving at speeds up to 30 km/h.

  2. The speed of metacognition: taking time to get to know one's structural knowledge.

    Science.gov (United States)

    Mealor, Andy D; Dienes, Zoltan

    2013-03-01

    The time course of different metacognitive experiences of knowledge was investigated using artificial grammar learning. Experiment 1 revealed that when participants are aware of the basis of their judgments (conscious structural knowledge) decisions are made most rapidly, followed by decisions made with conscious judgment but without conscious knowledge of underlying structure (unconscious structural knowledge), and guess responses (unconscious judgment knowledge) were made most slowly, even when controlling for differences in confidence and accuracy. In experiment 2, short response deadlines decreased the accuracy of unconscious but not conscious structural knowledge. Conversely, the deadline decreased the proportion of conscious structural knowledge in favour of guessing. Unconscious structural knowledge can be applied rapidly but becomes more reliable with additional metacognitive processing time whereas conscious structural knowledge is an all-or-nothing response that cannot always be applied rapidly. These dissociations corroborate quite separate theories of recognition (dual-process) and metacognition (higher order thought and cross-order integration). Copyright © 2012 Elsevier Inc. All rights reserved.

  3. Superplastic forming of 7475 Al sheet after friction stir processing (FSP)

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, M.; Bingel, W.H.; Fuller, C. [Rockwell Scientific Co., Thousand Oaks, CA (United States); Barnes, A.J. [Superform USA, Riverside, CA (United States)

    2004-07-01

    Since the invention of friction stir welding (FSW) in 1991, an increasing number of successful applications have been found for this unique solid-state welding technique. More recently, attention has been given to utilizing the mechanics of friction stirring to thermo-mechanically modify the microstructure of aluminum alloys to create or enhance superplasticity. Until now, superplasticity induced by friction stir processing (FSP) has only been demonstrated in small samples and evaluated by hot tensile elongation testing. The present work describes what we believe to be the first biaxial testing and full size component superplastic forming of friction stir processed aluminum sheet. The remarkable formability demonstrated in these 'first time' trials is described in detail. (orig.)

  4. A heteroscedastic generalized linear model with a non-normal speed factor for responses and response times.

    Science.gov (United States)

    Molenaar, Dylan; Bolsinova, Maria

    2017-05-01

    In generalized linear modelling of responses and response times, the observed response time variables are commonly transformed to make their distribution approximately normal. A normal distribution for the transformed response times is desirable as it justifies the linearity and homoscedasticity assumptions in the underlying linear model. Past research has, however, shown that the transformed response times are not always normal. Models have been developed to accommodate this violation. In the present study, we propose a modelling approach for responses and response times to test and model non-normality in the transformed response times. Most importantly, we distinguish between non-normality due to heteroscedastic residual variances, and non-normality due to a skewed speed factor. In a simulation study, we establish parameter recovery and the power to separate both effects. In addition, we apply the model to a real data set. © 2017 The Authors. British Journal of Mathematical and Statistical Psychology published by John Wiley & Sons Ltd on behalf of British Psychological Society.

  5. Space-Time Equalization for High-Speed Wireless Digital Communications Based on Multipath-Incorporating Matched Filtering, Zero Forcing Equalization, and MMSE

    National Research Council Canada - National Science Library

    Zoltowski, Michael D

    2003-01-01

    The project has successfully demonstrated reduced-rank, space-time equalization for high-speed wireless digital communications capable of reliably transmitting multimedia data in support of military...

  6. The Sidereal Time Variations of the Lorentz Force and Maximum Attainable Speed of Electrons

    Science.gov (United States)

    Nowak, Gabriel; Wojtsekhowski, Bogdan; Roblin, Yves; Schmookler, Barak

    2016-09-01

    The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab produces electrons that orbit through a known magnetic system. The electron beam's momentum can be determined through the radius of the beam's orbit. This project compares the beam orbit's radius while travelling in a transverse magnetic field with theoretical predictions from special relativity, which predict a constant beam orbit radius. Variations in the beam orbit's radius are found by comparing the beam's momentum entering and exiting a magnetic arc. Beam position monitors (BPMs) provide the information needed to calculate the beam momentum. Multiple BPM's are included in the analysis and fitted using the method of least squares to decrease statistical uncertainty. Preliminary results from data collected over a 24 hour period show that the relative momentum change was less than 10-4. Further study will be conducted including larger time spans and stricter cuts applied to the BPM data. The data from this analysis will be used in a larger experiment attempting to verify special relativity. While the project is not traditionally nuclear physics, it involves the same technology (the CEBAF accelerator) and the same methods (ROOT) as a nuclear physics experiment. DOE SULI Program.

  7. [The analytical setting of rotary speed of centrifuge rotor and centrifugation time in chemical, biochemical and microbiological practice].

    Science.gov (United States)

    Zolotarev, K V

    2012-08-01

    The researchers happen to face with suspensions in their chemical, biochemical and microbiological practice. The suspensions are the disperse systems with solid dispersed phase and liquid dispersion medium and with dispersed phase particle size > 100 nm (10-7 m). Quite often the necessity occurs to separate solid particles from liquid. To use for this purpose the precipitation in gravitation field can make the process to progress too long. In this respect an effective mode is the precipitation in the field of centrifugal forces--the centrifugation. The rotary speed of centrifuge rotor and centrifugation time can be set analytically using regularities of general dynamics and hydrodynamics. To this effect, should be written and transformed the equation of First and Second Newton Laws for suspension particle being in the field of centrifugal forces and forces of resistance of liquid and vessel wall. The force of liquid resistance depends on particle motion condition in liquid. To determine the regimen the Archimedes and Reynolds numerical dimensionless criteria are to be applied. The article demonstrates the results of these transformations as analytical inverse ratio dependence of centrifugation time from rotary speed. The calculation of series of "rate-time" data permits to choose the optimal data pair on the assumption of centrifuge capacity and practical reasonability. The results of calculations are validated by actual experimental data hence the physical mathematical apparatus can be considered as effective one. The setting progress depends both from parameter (Reynolds criterion) and data series calculation. So, the most convenient way to apply this operation is the programming approach. The article proposes to use the program Microsoft Excel and VBA programming language for this purpose. The possibility to download the file from Internet to use it for fast solution is proposed.

  8. Friction Stir Welding Process: A Green Technology

    OpenAIRE

    Esther T. Akinlabi; Stephen A. Akinlabi

    2012-01-01

    Friction Stir Welding (FSW) is a solid state welding process invented and patented by The Welding Institute (TWI) in the United Kingdom in 1991 for butt and lap welding of metals and plastics. This paper highlights the benefits of friction stir welding process as an energy efficient and a green technology process in the field of welding. Compared to the other conventional welding processes, its benefits, typical applications and its use in joining similar and dissimilar materia...

  9. Modeling and simulation of soft sensor design for real-time speed and position estimation of PMSM.

    Science.gov (United States)

    Omrane, Ines; Etien, Erik; Dib, Wissam; Bachelier, Olivier

    2015-07-01

    This paper deals with the design of a speed soft sensor for permanent magnet synchronous motor. At high speed, model-based soft sensor is used and it gives excellent results. However, it fails to deliver satisfactory performance at zero or very low speed. High-frequency soft sensor is used at low speed. We suggest to use a model-based soft sensor together with the high-frequency soft sensor to overcome the limitations of the first one at low speed range. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  10. Data Rods: High Speed, Time-Series Analysis of Massive Cryospheric Data Sets Using Object-Oriented Database Methods

    Science.gov (United States)

    Liang, Y.; Gallaher, D. W.; Grant, G.; Lv, Q.

    2011-12-01

    Change over time, is the central driver of climate change detection. The goal is to diagnose the underlying causes, and make projections into the future. In an effort to optimize this process we have developed the Data Rod model, an object-oriented approach that provides the ability to query grid cell changes and their relationships to neighboring grid cells through time. The time series data is organized in time-centric structures called "data rods." A single data rod can be pictured as the multi-spectral data history at one grid cell: a vertical column of data through time. This resolves the long-standing problem of managing time-series data and opens new possibilities for temporal data analysis. This structure enables rapid time- centric analysis at any grid cell across multiple sensors and satellite platforms. Collections of data rods can be spatially and temporally filtered, statistically analyzed, and aggregated for use with pattern matching algorithms. Likewise, individual image pixels can be extracted to generate multi-spectral imagery at any spatial and temporal location. The Data Rods project has created a series of prototype databases to store and analyze massive datasets containing multi-modality remote sensing data. Using object-oriented technology, this method overcomes the operational limitations of traditional relational databases. To demonstrate the speed and efficiency of time-centric analysis using the Data Rods model, we have developed a sea ice detection algorithm. This application determines the concentration of sea ice in a small spatial region across a long temporal window. If performed using traditional analytical techniques, this task would typically require extensive data downloads and spatial filtering. Using Data Rods databases, the exact spatio-temporal data set is immediately available No extraneous data is downloaded, and all selected data querying occurs transparently on the server side. Moreover, fundamental statistical

  11. Microstructure and pitting corrosion of friction stir welded joints in 2219-O aluminum alloy thick plate

    International Nuclear Information System (INIS)

    Xu Weifeng; Liu Jinhe

    2009-01-01

    Effect of welding parameters on the microstructure and pitting corrosion of different positions along the thickness of weld nugget zone in friction stir welded 2219-O aluminum alloy plate was investigated using scanning electron microscopy (SEM), polarization experiment and electrochemical impedance tests (EIS). It was found that the material presents significant passivation and the top has best corrosion resistance compared to the bottom and base material. Corrosion resistance decreases with the increase of traverse speed from 60 to 100 mm/min at rotary speed 400 rpm. Corrosion resistance at rotary speed 600 rpm is lower than that at 500 rpm.

  12. Effect of Post Heat Treatment on the Microstructure and Microhardness of Friction Stir Processed NiAl Bronze (NAB Alloy

    Directory of Open Access Journals (Sweden)

    Yuting Lv

    2015-09-01

    Full Text Available NiAl bronze (NAB alloy is prepared by using friction stir processing (FSP technique at a tool rotation rate of 1200 rpm and a traverse speed of 150 mm/min. A post heat treatment is performed at the temperature of 675 °C. The effect of heat treatment on the microstructure and microhardness is studied. The results show that the microstructure of the FSP NAB alloy consists of high density dislocations, retained β phase (β′ phase and recrystallized grains. When annealed at 675 °C, discontinuous static recrystallization (DSRX takes place. The content of β′ phase gradually decreases and fine κ phase is precipitated. After annealing for 2 h, both the microhardness of the FSP sample in the stir zone (SZ and the difference in hardness between the SZ and base metal decrease due to the reduction of the dislocation density and β′ phase, accompanying recrystallized grain coarsening. With further increasing of the annealing time to 4 h, the aforementioned difference in hardness nearly disappears.

  13. Effect of process parameters on microstructure and mechanical properties of friction stir welded joints: A review

    Science.gov (United States)

    Wanare, S. P.; Kalyankar, V. D.

    2018-04-01

    Friction stir welding is emerging as a promising technique for joining of lighter metal alloys due to its several advantages over conventional fusion welding processes such as low thermal distortion, good mechanical properties, fine weld joint microstructure, etc. This review article mainly focuses on analysis of microstructure and mechanical properties of friction stir welded joints. Various microstructure characterization techniques used by previous researchers such as optical microscopes, x-ray diffraction, electron probe microscope, transmission electron microscope, scanning electron microscopes with electron back scattered diffraction, electron dispersive microscopy, etc. are thoroughly overviewed and their results are discussed. The effects of friction stir welding process parameters such as tool rotational speed, welding speed, tool plunge depth, axial force, tool shoulder diameter to tool pin diameter ratio, tool geometry etc. on microstructure and mechanical properties of welded joints are studied and critical observations are noted down. The microstructure examination carried out by previous researchers on various zones of welded joints such as weld zone, heat affected zone and base metal are studied and critical remarks have been presented. Mechanical performances of friction stir welded joints based on tensile test, micro-hardness test, etc. are discussed. This article includes exhaustive literature review of standard research articles which may become ready information for subsequent researchers to establish their line of action.

  14. Effect of shoulder to pin ratio on magnesium alloy Friction Stir Welding

    Science.gov (United States)

    Othman, N. H.; Ishak, M.; Shah, L. H.

    2017-09-01

    This study focuses on the effect of shoulder to pin diameter ratio on friction stir welding of magnesium alloy AZ31. Two pieces of AZ31 alloy with thickness of 2 mm were friction stir welded by using conventional milling machine. The shoulder to pin diameter ratio used in this experiment are 2.25, 2.5, 2.75, 3, 3.33, 3.66, 4.5, 5 and 5.5. The rotational speed and welding speed used in this study are 1000 rpm and 100 mm/min, respectively. Microstructure observation of welded area was studied by using optical microscope. Equiaxed grains were observed at the TMAZ and stir zone indicating fully plastic deformation. The grain size of stir zone increased with decreasing shoulder to pin ratio from ratio 3.33 to 5.5 due to higher heat input. It is observed that, surface galling and faying surface defect is produced when excessive heat input is applied. To evaluate the mechanical properties of this specimen, tensile test was used in this study. Shoulder to pin ratio 5.5 shows lowest tensile strength while shoulder to pin diameter ratio 3.33 shows highest tensile strength with weld efficiency 91 % from based metal.

  15. Microstructural characteristics and effects of TC4 titanium alloy processed by using friction stir welding

    Directory of Open Access Journals (Sweden)

    Bo LI

    2016-02-01

    Full Text Available Friction stir welding technique is used for the processing of TC4 titanium alloy under protective atmosphere, and it results with good formability. The research focues on the evolution mechanisms of α+β dual phase microstructure in stirred zone and the effects of processing parameters on structures hardness. The results show that with optimized technological parameters, stir zone structure experiences the α/β transformation, and finally changes to the α+β duplex structure which is based on the β phase. After mixing head leaves and the structure cools, the precipitated lamellar α phase is among and/or within-regions. Grain refining of α+β dual phase is obvious. The shortened α/β lamellar spacing distance may improve the strengthening effect of the α+β duplex phase and enhance the hardness of the stir zone. The increasing of the tool rotation speed could coarsen β-regions, while the increasing of the travel speed could help reduce the α phase ratio and generate needle-type Martensites.

  16. Tensile behavior of friction stir welded AA 6061-T4 aluminum alloy joints

    International Nuclear Information System (INIS)

    Heidarzadeh, A.; Khodaverdizadeh, H.; Mahmoudi, A.; Nazari, E.

    2012-01-01

    Highlights: ► Range of parameters for defect-free friction stir welded AA 6061-T4 was reached. ► A model was developed for predicting UTS and EL of friction stir welded AA 6061-T4. ► The maximum values of UTS and EL of joints were estimated by developed model. ► The optimum values of FSW process parameters were determined. -- Abstract: In this investigation response surface methodology based on a central composite rotatable design with three parameters, five levels and 20 runs, was used to develop a mathematical model predicting the tensile properties of friction stir welded AA 6061-T4 aluminum alloy joints at 95% confidence level. The three welding parameters considered were tool rotational speed, welding speed and axial force. Analysis of variance was applied to validate the predicted model. Microstructural characterization and fractography of joints were examined using optical and scanning electron microscopes. Also, the effects of the welding parameters on tensile properties of friction stir welded joints were analyzed in detail. The results showed that the optimum parameters to get a maximum of tensile strength were 920 rev/min, 78 mm/min and 7.2 kN, where the maximum of tensile elongation was obtained at 1300 rev/min, 60 mm/min and 8 kN.

  17. Measurement of the speed of sound in trabecular bone by using a time reversal acoustics focusing system

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang Il [Kangwon National University, Chuncheon (Korea, Republic of); Choi, Bok-Kyoung [Maritime Security Research Center, KIOST, Ansan (Korea, Republic of)

    2014-10-15

    A new method for measuring the speed of sound (SOS) in trabecular bone by using a time reversal acoustics (TRA) focusing system was proposed and validated with measurements obtained by using the conventional pulse-transmission technique. The SOS measured in 14 bovine femoral trabecular bone samples by using the two methods was highly correlated each other, although the SOS measured by using the TRA focusing system was slightly lower by an average of 2.2 m/s. The SOS measured by using the two methods showed high correlation coefficients of r = 0.92 with the apparent bone density, consistent with the behavior in human trabecular bone in vitro. These results prove the efficacy of the new method based on the principle of TRA to measure the SOS in trabecular bone.

  18. High-speed extended-term time-domain simulation for online cascading analysis of power system

    Science.gov (United States)

    Fu, Chuan

    A high-speed extended-term (HSET) time domain simulator (TDS), intended to become a part of an energy management system (EMS), has been newly developed for use in online extended-term dynamic cascading analysis of power systems. HSET-TDS includes the following attributes for providing situational awareness of high-consequence events: (i) online analysis, including n-1 and n-k events, (ii) ability to simulate both fast and slow dynamics for 1-3 hours in advance, (iii) inclusion of rigorous protection-system modeling, (iv) intelligence for corrective action ID, storage, and fast retrieval, and (v) high-speed execution. Very fast on-line computational capability is the most desired attribute of this simulator. Based on the process of solving algebraic differential equations describing the dynamics of power system, HSET-TDS seeks to develop computational efficiency at each of the following hierarchical levels, (i) hardware, (ii) strategies, (iii) integration methods, (iv) nonlinear solvers, and (v) linear solver libraries. This thesis first describes the Hammer-Hollingsworth 4 (HH4) implicit integration method. Like the trapezoidal rule, HH4 is symmetrically A-Stable but it possesses greater high-order precision (h4 ) than the trapezoidal rule. Such precision enables larger integration steps and therefore improves simulation efficiency for variable step size implementations. This thesis provides the underlying theory on which we advocate use of HH4 over other numerical integration methods for power system time-domain simulation. Second, motivated by the need to perform high speed extended-term time domain simulation (HSET-TDS) for on-line purposes, this thesis presents principles for designing numerical solvers of differential algebraic systems associated with power system time-domain simulation, including DAE construction strategies (Direct Solution Method), integration methods(HH4), nonlinear solvers(Very Dishonest Newton), and linear solvers(SuperLU). We have

  19. Seasonal trend analysis and ARIMA modeling of relative humidity and wind speed time series around Yamula Dam

    Science.gov (United States)

    Eymen, Abdurrahman; Köylü, Ümran

    2018-02-01

    Local climate change is determined by analysis of long-term recorded meteorological data. In the statistical analysis of the meteorological data, the Mann-Kendall rank test, which is one of the non-parametrical tests, has been used; on the other hand, for determining the power of the trend, Theil-Sen method has been used on the data obtained from 16 meteorological stations. The stations cover the provinces of Kayseri, Sivas, Yozgat, and Nevşehir in the Central Anatolia region of Turkey. Changes in land-use affect local climate. Dams are structures that cause major changes on the land. Yamula Dam is located 25 km northwest of Kayseri. The dam has huge water body which is approximately 85 km2. The mentioned tests have been used for detecting the presence of any positive or negative trend in meteorological data. The meteorological data in relation to the seasonal average, maximum, and minimum values of the relative humidity and seasonal average wind speed have been organized as time series and the tests have been conducted accordingly. As a result of these tests, the following have been identified: increase was observed in minimum relative humidity values in the spring, summer, and autumn seasons. As for the seasonal average wind speed, decrease was detected for nine stations in all seasons, whereas increase was observed in four stations. After the trend analysis, pre-dam mean relative humidity time series were modeled with Autoregressive Integrated Moving Averages (ARIMA) model which is statistical modeling tool. Post-dam relative humidity values were predicted by ARIMA models.

  20. High-Speed Rail Train Timetabling Problem: A Time-Space Network Based Method with an Improved Branch-and-Price Algorithm

    Directory of Open Access Journals (Sweden)

    Bisheng He

    2014-01-01

    Full Text Available A time-space network based optimization method is designed for high-speed rail train timetabling problem to improve the service level of the high-speed rail. The general time-space path cost is presented which considers both the train travel time and the high-speed rail operation requirements: (1 service frequency requirement; (2 stopping plan adjustment; and (3 priority of train types. Train timetabling problem based on time-space path aims to minimize the total general time-space path cost of all trains. An improved branch-and-price algorithm is applied to solve the large scale integer programming problem. When dealing with the algorithm, a rapid branching and node selection for branch-and-price tree and a heuristic train time-space path generation for column generation are adopted to speed up the algorithm computation time. The computational results of a set of experiments on China’s high-speed rail system are presented with the discussions about the model validation, the effectiveness of the general time-space path cost, and the improved branch-and-price algorithm.

  1. Serial quantitative MR assessment of optic neuritis in a case of neuromyelitis optica, using gadolinium-'enhanced' STIR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Barkhof, F.; Scheltens, P.; Valk, J. (Vrije Univ., Amsterdam (Netherlands). Dept. of Diagnostic Radiology); Waalewijn, C.; Uitdehaag, B.M.J.; Polman, C.H. (Vrije Univ., Amsterdam (Netherlands). Dept. of Neurology)

    1991-02-01

    A patient is presented with neuromyelitis optica. MR imaging, using a short inversion time inversion recovery (STIR) technique, clearly depicted the lesion in the left optic nerve. Subsequent serial STIR imaging, with and without Gadolinium-DTPA, allowed quantitative assessment of changes parallel to improved optic nerve function. STIR imaging is a sensitive technique to demonstrate optic nerve lesions, and enables quantitative assessment to be made of the effect of (steroid) medication. (orig.).

  2. Heat generation during plunge stage in friction stir welding

    Directory of Open Access Journals (Sweden)

    Veljić Darko M.

    2013-01-01

    Full Text Available This paper deals with the heat generation in the Al alloy Al2024-T3 plate under different rotating speeds and plunge speeds during the plunge stage of friction stir welding (FSW. A three-dimensional finite element model (FEM is developed in the commercial code ABAQUS/Explicit using the arbitrary Lagrangian-Eulerian formulation, the Johnson-Cook material law and Coulomb’s Law of friction. The heat generation in FSW can be divided into two parts: frictional heat generated by the tool and heat generated by material deformation near the pin and the tool shoulder region. Numerical results obtained in this work indicate a more prominent influence from the friction-generated heat. The slip rate of the tool relative to the workpiece material is related to this portion of heat. The material velocity, on the other hand, is related to the heat generated by plastic deformation. Increasing the plunging speed of the tool decreases the friction-generated heat and increases the amount of deformation-generated heat, while increasing the tool rotating speed has the opposite influence on both heat portions. Numerical results are compared with the experimental ones, in order to validate the numerical model, and a good agreement is obtained.

  3. Asymmetric modes and complex time eigenvalues of the one-speed neutron transport equation in a homogeneous sphere

    International Nuclear Information System (INIS)

    Paranjape, S.D.; Kumar, V.; Sahni, D.C.

    1993-01-01

    The one-speed, time-dependent, isotropically scattering, integral transport equation in a homogeneous sphere has been converted into a criticality-like problem by considering exponential time behaviour of the scalar flux. This criticality problem has been converted into a matrix eigenvalue problem using the Fourier transform technique. The time eigenvalues λ, which are complex in general, have been determined for spherically symmetric as well as asymmetric modes. For the former case, the real decay constants and the real parts of complex decay constants decrease monotonically with increasing system size and form two distinct families of single-valued functions. For the spherically asymmetric modes, certain new features emerge. The real decay constants are found to be multi-valued functions of system size and they do not always decrease monotonically with increasing system size. As the system size increases from zero onwards, the decay constants alternate between complex and real values and the real and complex decay constant curves interlace. (Author)

  4. Nonequilibrium chemical instabilities in continuous flow stirred tank reactors: The effect of stirring

    International Nuclear Information System (INIS)

    Horsthemke, W.; Hannon, L.

    1984-01-01

    We present a stochastic model for stirred chemical reactors. In the limiting case of practical interest, i.e., fast stirring, we solve for the characteristic function in steady state and derive expressions for the stationary moments through a perturbation expansion. Moments are explicitly calculated for a generic model of bistable behavior. We find that stirring decreases the area of the bistable region essentially by changing the point of transition from the high reaction rate state to the low reaction rate state. This is in remarkable agreement with the experimental findings of Roux, et al. Our results indicate that stirring should not be considered simply as an ''enhanced diffusion'' process and that nucleation plays only a minor role in transitions between multiple steady states in a continuous flow stirred tank reactor (CSTR)

  5. Stir zone microstructure of commercial purity titanium friction stir welded using pcBN tool

    International Nuclear Information System (INIS)

    Zhang Yu; Sato, Yutaka S.; Kokawa, Hiroyuki; Park, Seung Hwan C.; Hirano, Satoshi

    2008-01-01

    In the present study, friction stir welding was applied to commercial purity titanium using a polycrystalline cubic boron nitride tool, and microstructure and hardness in the weld were examined. Additionally, the microstructural evolution during friction stir welding was also discussed. The stir zone consisted of fine equiaxed α grains surrounded by serrate grain boundaries, which were produced through the β → α allotropic transformation during the cooling cycle of friction stir welding. The fine α grains caused higher hardness than that in the base material. A lath-shaped α grain structure containing Ti borides and tool debris was observed in the surface region of the stir zone, whose hardness was the highest in the weld

  6. Determinants of translation speed are randomly distributed across transcripts resulting in a universal scaling of protein synthesis times

    Science.gov (United States)

    Sharma, Ajeet K.; Ahmed, Nabeel; O'Brien, Edward P.

    2018-02-01

    Ribosome profiling experiments have found greater than 100-fold variation in ribosome density along mRNA transcripts, indicating that individual codon elongation rates can vary to a similar degree. This wide range of elongation times, coupled with differences in codon usage between transcripts, suggests that the average codon translation-rate per gene can vary widely. Yet, ribosome run-off experiments have found that the average codon translation rate for different groups of transcripts in mouse stem cells is constant at 5.6 AA/s. How these seemingly contradictory results can be reconciled is the focus of this study. Here, we combine knowledge of the molecular factors shown to influence translation speed with genomic information from Escherichia coli, Saccharomyces cerevisiae and Homo sapiens to simulate the synthesis of cytosolic proteins in these organisms. The model recapitulates a near constant average translation rate, which we demonstrate arises because the molecular determinants of translation speed are distributed nearly randomly amongst most of the transcripts. Consequently, codon translation rates are also randomly distributed and fast-translating segments of a transcript are likely to be offset by equally probable slow-translating segments, resulting in similar average elongation rates for most transcripts. We also show that the codon usage bias does not significantly affect the near random distribution of codon translation rates because only about 10 % of the total transcripts in an organism have high codon usage bias while the rest have little to no bias. Analysis of Ribo-Seq data and an in vivo fluorescent assay supports these conclusions.

  7. An experimental and modeling study of propene oxidation. Part 2: Ignition delay time and flame speed measurements

    KAUST Repository

    Burke, Sinéad M.

    2015-02-01

    Experimental data obtained in this study (Part II) complement the speciation data presented in Part I, but also offer a basis for extensive facility cross-comparisons for both experimental ignition delay time (IDT) and laminar flame speed (LFS) observables. To improve our understanding of the ignition characteristics of propene, a series of IDT experiments were performed in six different shock tubes and two rapid compression machines (RCMs) under conditions not previously studied. This work is the first of its kind to directly compare ignition in several different shock tubes over a wide range of conditions. For common nominal reaction conditions among these facilities, cross-comparison of shock tube IDTs suggests 20-30% reproducibility (2σ) for the IDT observable. The combination of shock tube and RCM data greatly expands the data available for validation of propene oxidation models to higher pressures (2-40. atm) and lower temperatures (750-1750. K).Propene flames were studied at pressures from 1 to 20. atm and unburned gas temperatures of 295-398. K for a range of equivalence ratios and dilutions in different facilities. The present propene-air LFS results at 1. atm were also compared to LFS measurements from the literature. With respect to initial reaction conditions, the present experimental LFS cross-comparison is not as comprehensive as the IDT comparison; however, it still suggests reproducibility limits for the LFS observable. For the LFS results, there was agreement between certain data sets and for certain equivalence ratios (mostly in the lean region), but the remaining discrepancies highlight the need to reduce uncertainties in laminar flame speed experiments amongst different groups and different methods. Moreover, this is the first study to investigate the burning rate characteristics of propene at elevated pressures (>5. atm).IDT and LFS measurements are compared to predictions of the chemical kinetic mechanism presented in Part I and good

  8. An experimental and modeling study of propene oxidation. Part 2: Ignition delay time and flame speed measurements

    KAUST Repository

    Burke, Siné ad M.; Burke, Ultan; Mc Donagh, Reuben; Mathieu, Olivier; Osorio, Irmis; Keesee, Charles L.; Morones, Aní bal; Petersen, Eric L.; Wang, Weijing; DeVerter, Trent A.; Oehlschlaeger, Matthew A.; Rhodes, Brandie; Hanson, Ronald K.; Davidson, David F.; Weber, Bryan W.; Sung, Chihjen; Santner, Jeffrey S.; Ju, Yiguang; Haas, Francis M.; Dryer, Frederick L.; Volkov, Evgeniy N.; Nilsson, Elna J K; Konnov, Alexander A.; Alrefae, Majed; Khaled, Fathi; Farooq, Aamir; Dirrenberger, Patricia; Glaude, Pierre Alexandre; Battin-Leclerc, F.; Curran, Henry J.

    2015-01-01

    Experimental data obtained in this study (Part II) complement the speciation data presented in Part I, but also offer a basis for extensive facility cross-comparisons for both experimental ignition delay time (IDT) and laminar flame speed (LFS) observables. To improve our understanding of the ignition characteristics of propene, a series of IDT experiments were performed in six different shock tubes and two rapid compression machines (RCMs) under conditions not previously studied. This work is the first of its kind to directly compare ignition in several different shock tubes over a wide range of conditions. For common nominal reaction conditions among these facilities, cross-comparison of shock tube IDTs suggests 20-30% reproducibility (2σ) for the IDT observable. The combination of shock tube and RCM data greatly expands the data available for validation of propene oxidation models to higher pressures (2-40. atm) and lower temperatures (750-1750. K).Propene flames were studied at pressures from 1 to 20. atm and unburned gas temperatures of 295-398. K for a range of equivalence ratios and dilutions in different facilities. The present propene-air LFS results at 1. atm were also compared to LFS measurements from the literature. With respect to initial reaction conditions, the present experimental LFS cross-comparison is not as comprehensive as the IDT comparison; however, it still suggests reproducibility limits for the LFS observable. For the LFS results, there was agreement between certain data sets and for certain equivalence ratios (mostly in the lean region), but the remaining discrepancies highlight the need to reduce uncertainties in laminar flame speed experiments amongst different groups and different methods. Moreover, this is the first study to investigate the burning rate characteristics of propene at elevated pressures (>5. atm).IDT and LFS measurements are compared to predictions of the chemical kinetic mechanism presented in Part I and good

  9. Grain refinement of Aluminium alloys using friction stir processing

    International Nuclear Information System (INIS)

    Khraisheh, M.

    2004-01-01

    Full text.Friction Stir Processing (FSP) is a new advanced material processing technique used to refine and homogenize the microstructure of sheet metals. FSP is a solid state processing technique that uses a rapidly rotating non-consumable high strength tool steel pin that extends from a cylindrical shoulder. The rotating pin is forced with a predetermined load into the work piece and moved along with the work pieces, while the rotating pin deforms and stirs the locally heated material. It is a hot working process in which a large amount of deformation is imparted to the sheet. FS processed zone is characterized by dynamic recrystallization which results in grain refinement . this promising emerging process needs further investigations to develop optimum process parameters to produce the desired microstructure. In this work, we present preliminary results on the effects of rotational and translational speeds on grain refinement of AA5052. Under certain processing conditions, sub-micron grain structure was produced using this technique

  10. The Effect of Cu Powder During Friction Stir Welding on Microstructure and Mechanical Properties of AA3003-H18

    Science.gov (United States)

    Abnar, B.; Kazeminezhad, M.; Kokabi, A. H.

    2014-08-01

    Friction stir welding (FSW) was used to join 3003-H18 non-heat-treatable aluminum alloy plates by adding copper powder. The copper powder was first added to the gap (0.1 and 0.2 mm) between two plates and then the FSW was performed. The specimens were joined at various rotational speeds of 800, 1000, and 1200 rpm at traveling speeds of 70 and 100 mm/min. The effects of rotational speed, second pass of FSW, and direction of second pass also were studied on copper particle distribution and formation of Al-Cu intermetallic compounds in the stir zone. The second pass of FSW was carried out in two ways; in line with the first pass direction (2F) and in the reverse direction of the first pass (FB). The microstructure, mechanical properties, and formation of intermetallic compounds type were investigated. In high copper powder compaction into the gap, large clusters were formed in the stir zone, while fine clusters and sound copper particles distribution were obtained in low powder compaction. The copper particle distribution and amount of Al-Cu intermetallic compounds were increased in the stir zone with increasing the rotational speed and applying the second pass. Al2Cu and AlCu intermetallic phases were formed in the stir zone and consequently the hardness was significantly increased. The copper particles and in situ intermetallic compounds were symmetrically distributed in both advancing and retreating sides of weld zone after FB passes. Thus, the wider area was reinforced by the intermetallic compounds. Also, the tensile test specimens tend to fracture from the coarse copper aggregation at the low rotational speeds. At high rotational speeds, the fracture locations are placed in HAZ and TMAZ.

  11. Effect of cryogenic cooling on corrosion of friction stir welded AA7010-T7651

    DEFF Research Database (Denmark)

    Jariyaboon, Manthana; Davenport, A. J.; Ambat, Rajan

    2010-01-01

    Purpose - The purpose of this paper is to study how cryogenic CO2 cooling during the welding process affects corrosion behaviour of friction stir welding (FSW) AA7010-T7651. Design/methodology/approach - Friction stir welded AA7010-17651 was produced with a rotation speed of 288 rpm and a travel...... speed of 58 mm/min. The liquid CO2 was sprayed onto the weld centre line immediately after the toolpiece. The microstructures of welds in different regions were observed using Field Emission Gun Scanning Electron Microscope (FEG-SEM). The effect on the corrosion susceptibility was investigated using...... a gel visualisation test and potentiodynamic polarisation measurements using a micro-electrochemical technique. Findings - The main corrosion region for both FSWs AA7010-T7651 produced with and without cryogenic CO2 cooling is in the HAZ region, which exhibited intergranular attack. Cryogenic cooling...

  12. Friction stir welding: multi-response optimisation using Taguchi-based GRA

    Directory of Open Access Journals (Sweden)

    Jitender Kundu

    2016-01-01

    Full Text Available In present experimental work, friction stir welding of aluminium alloy 5083- H321 is performed for optimisation of process parameters for maximum tensile strength. Taguchi’s L9 orthogonal array has been used for three parameters – tool rotational speed (TRS, traverse speed (TS, and tool tilt angle (TTA with three levels. Multi-response optimisation has been carried out through Taguchi-based grey relational analysis. The grey relational grade has been calculated for all three responses – ultimate tensile strength, percentage elongation, and micro-hardness. Analysis of variance is the tool used for obtaining grey relational grade to find out the significant process parameters. TRS and TS are the two most significant parameters which influence most of the quality characteristics of friction stir welded joint. Validation of predicted values done through confirmation experiments at optimum setting shows a good agreement with experimental values.

  13. Material Characterization of Dissimilar Friction Stir Spot Welded Aluminium and Copper Alloy

    Science.gov (United States)

    Sanusi, K. O.; Akinlabi, E. T.

    2017-08-01

    In this research study, material characterization of dissimilar friction stir spot welded Aluminium and Copper was evaluated. Rotational speeds of 800 rpm and transverse speeds of 50 mm/min, 150 mm/min and 250 mm/min were used. The total numbers of samples evaluated were nine altogether. The spot welds were characterised by microstructure characterization using optical microscope (OEM) and scanning electron microscopy technique (SEM) by observing the evolution of the microstructure across the weld’s cross-section. lap-shear test of the of the spot weld specimens were also done. From the results, it shows that welding of metals and alloys using Friction stir spot welding is appropriate and can be use in industrial applications.

  14. Friction stir welding of dissimilar AA2024 and AA7075 aluminum alloys

    International Nuclear Information System (INIS)

    Khodir, Saad Ahmed; Shibayanagi, Toshiya

    2008-01-01

    The present study focuses on the microstructure and mechanical properties of dissimilar joints of 2024-T3 Al alloy to 7075-T6 Al alloy produced by friction stir welding. Effects of welding speed and fixed location of base metals on microstructures, hardness distributions, and tensile properties of the welded joints were investigated. SEM-EDS analysis revealed that the stir zone contains a mixed structure and onion ring pattern with a periodic change of grain size as well as a heterogeneous distribution of alloying elements. The maximum tensile strength of 423.0 MPa was achieved for the joint produced at welding speed of 1.67 mm/s when 2024 Al alloy was located on the advancing side

  15. Impeller Submergence Depth for Stirred Tanks

    Directory of Open Access Journals (Sweden)

    Thiyam T. Devi

    2011-11-01

    Full Text Available Impeller submergence governs the performance of mixing tanks employed in oxygen transfer operation. Present work experimentally investigates the effect of impeller submergence depths on oxygen transfer and corresponding power consumption. It has been found that at higher range of impeller submergence, mixing tanks consume less power and gives higher values of oxygen transfer coefficient. Optimal range of submergence depth is 0.7 to 0.9 times the impeller diameter. Copyright ©2011 BCREC UNDIP. All rights reserved.(Received: 4th March 2011; Revised: 12nd July 2011; Accepted: 14th July 2011[How to Cite: T.T. Devi, A.P. Sinha, M. Thakre, and B. Kumar. (2011. Impeller Submergence Depth for Stirred Tanks. Bulletin of Chemical Reaction Engineering & Catalysis, 6 (2: 123-128. doi:10.9767/bcrec.6.2.826.123-128][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.2.826.123-128 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/826] | View in 

  16. Effect of Friction Stir Welding Parameters on the Mechanical and Microstructure Properties of the Al-Cu Butt Joint

    Directory of Open Access Journals (Sweden)

    Sare Celik

    2016-05-01

    Full Text Available Friction Stir Welding (FSW is a solid-state welding process used for welding similar and dissimilar materials. FSW is especially suitable to join sheet Al alloys, and this technique allows different material couples to be welded continuously. In this study, 1050 Al alloys and commercially pure Cu were produced at three different tool rotation speeds (630, 1330, 2440 rpm and three different tool traverse speeds (20, 30, 50 mm/min with four different tool position (0, 1, 1.5, 2 mm by friction stir welding. The influence of the welding parameters on the microstructure and mechanical properties of the joints was investigated. Tensile and bending tests and microhardness measurements were used to determine the mechanical properties. The microstructures of the weld zone were investigated by optical microscope and scanning electron microscope (SEM and were analyzed in an energy dispersed spectrometer (EDS. Intermetallic phases were detected based on the X-ray diffraction (XRD analysis results that evaluated the formation of phases in the weld zone. When the welding performance of the friction stir welded butt joints was evaluated, the maximum value obtained was 89.55% with a 1330 rpm tool rotational speed, 20 mm/min traverse speed and a 1 mm tool position configuration. The higher tensile strength is attributed to the dispersion strengthening of the fine Cu particles distributed over the Al material in the stir zone region.

  17. Microstructure and mechanical properties of similar and dissimilar joints of aluminium alloy and pure copper by friction stir welding

    Directory of Open Access Journals (Sweden)

    V.C. Sinha

    2016-09-01

    Full Text Available In the present study, the microstructure and mechanical properties of similar and dissimilar friction stir welded joints of aluminium alloy (AlA and pure copper (Cu were evaluated at variable tool rotational speeds from 150 to 900 rpm in steps of 150 rpm at 60 mm/min travel speed and constant tilt angle 2°. The interfacial microstructures of the joints were characterised by optical and scanning electron microscopy. The Al4Cu9, AlCu, Al2Cu and Al2Cu3 intermetallic compounds have been observed at the interface and stir zone region of dissimilar Al/Cu FSWed joints. Variation in the grain size was observed in the stir zone depending upon the heat input value. Axial force, traverse force and torque value were analysed with variation in tool rotational speed. Residual stresses were measured at the stir zone by X-ray diffraction technique. Maximum ultimate tensile strength of ∼75% of AlA strength for AlA–AlA joints has been obtained at 750 rpm and for Cu–Cu joint tensile strength of ∼100% of tensile strength of Cu was obtained at 300 rpm. However, for Cu–AlA joint when processed at 600 rpm tool rotational speed achieved maximum ultimate tensile strength of ∼77% of AlA.

  18. Effects of Injection Timing on Fluid Flow Characteristics of Partially Premixed Combustion Based on High-Speed Particle Image Velocimetry

    KAUST Repository

    Izadi Najafabadi, Mohammad

    2017-03-28

    Partially Premixed Combustion (PPC) is a promising combustion concept ,based on judicious tuning of the charge stratification, to meet the increasing demands of emission legislation and to improve fuel efficiency. Longer ignition delays of PPC in comparison with conventional diesel combustion provide better fuel/air mixture which decreases soot and NO emissions. Moreover, a proper injection timing and strategy for PPC can improve the combustion stability as a result of a higher level of fuel stratification in comparison with the Homogeneous Charge Compression Ignition (HCCI) concept. Injection timing is the major parameter with which to affect the level of fuel and combustion stratification and to control the combustion phasing and the heat release behavior. The scope of the present study is to investigate the fluid flow characteristics of PPC at different injection timings. To this end, high-speed Particle Image Velocimetry (PIV) is implemented in a light-duty optical engine to measure fluid flow characteristics, including the flow fields, mean velocity and cycle-resolved turbulence, inside the piston bowl as well as the squish region with a temporal resolution of 1 crank angle degree at 800 rpm. Two injectors, having 5 and 7 holes, were compared to see their effects on fluid flow and heat release behavior for different injection timings. Reactive and non-reactive measurements were performed to distinguish injection-driven and combustion-driven turbulence. Formation of vortices and higher turbulence levels enhance the air/fuel interaction, changing the level of fuel stratification and combustion duration. Results demonstrate clearly how turbulence level correlates with heat release behavior, and provide a quantitative dataset for validation of numerical simulations.

  19. Modeling Stepped Leaders Using a Time Dependent Multi-dipole Model and High-speed Video Data

    Science.gov (United States)

    Karunarathne, S.; Marshall, T.; Stolzenburg, M.; Warner, T. A.; Orville, R. E.

    2012-12-01

    In summer of 2011, we collected lightning data with 10 stations of electric field change meters (bandwidth of 0.16 Hz - 2.6 MHz) on and around NASA/Kennedy Space Center (KSC) covering nearly 70 km × 100 km area. We also had a high-speed video (HSV) camera recording 50,000 images per second collocated with one of the electric field change meters. In this presentation we describe our use of these data to model the electric field change caused by stepped leaders. Stepped leaders of a cloud to ground lightning flash typically create the initial path for the first return stroke (RS). Most of the time, stepped leaders have multiple complex branches, and one of these branches will create the ground connection for the RS to start. HSV data acquired with a short focal length lens at ranges of 5-25 km from the flash are useful for obtaining the 2-D location of these multiple branches developing at the same time. Using HSV data along with data from the KSC Lightning Detection and Ranging (LDAR2) system and the Cloud to Ground Lightning Surveillance System (CGLSS), the 3D path of a leader may be estimated. Once the path of a stepped leader is obtained, the time dependent multi-dipole model [ Lu, Winn,and Sonnenfeld, JGR 2011] can be used to match the electric field change at various sensor locations. Based on this model, we will present the time-dependent charge distribution along a leader channel and the total charge transfer during the stepped leader phase.

  20. Microstructure and mechanical properties of friction stir welded Al/Mg2Si metal matrix cast composite

    International Nuclear Information System (INIS)

    Nami, H.; Adgi, H.; Sharifitabar, M.; Shamabadi, H.

    2011-01-01

    In this research, friction stir weldability of 15 wt.% Mg 2 Si particulate aluminum matrix cast composite and effects of tool rotation speed and number of welding passes on microstructure and mechanical properties of the joints were investigated. Microstructural observations were carried out by employing optical and scanning electron microscopy of the cross sections perpendicular to the tool traverse direction. Mechanical properties including microhardness and tensile strength were evaluated in detail. The results showed fragmentation of Mg 2 Si particles and Mg 2 Si needles existing in eutectic structure in stir zone. Also, homogeneous distribution of Mg 2 Si particles was observed in the stir zone as a result of stirring with high plastic strains. Tension test results indicated that tensile strength of the joint had an optimum at 1120 rpm tool rotation speed and decreased with increasing of the number of welding passes. Hardness of the joint increased due to modification of solidification microstructure of the base composite. This research indicates that friction stir welding is a good candidate for joining of 15 wt.% Mg 2 Si aluminum matrix composite castings.

  1. Microstructure and mechanical properties of friction stir welded 18Cr–2Mo ferritic stainless steel thick plate

    International Nuclear Information System (INIS)

    Han, Jian; Li, Huijun; Zhu, Zhixiong; Barbaro, Frank; Jiang, Laizhu; Xu, Haigang; Ma, Li

    2014-01-01

    Highlights: • We focus on friction stir welding of 18Cr–2Mo ferritic stainless steel thick plate. • We produce high-quality joints with special tool and optimised welding parameters. • We compare microstructure and mechanical properties of steel and joint. • Friction stir welding is a method that can maintain the properties of joint. - Abstract: In this study, microstructure and mechanical properties of a friction stir welded 18Cr–2Mo ferritic stainless steel thick plate were investigated. The 5.4 mm thick plates with excellent properties were welded at a constant rotational speed and a changeable welding speed using a composite tool featuring a chosen volume fraction of cubic boron nitride (cBN) in a W–Re matrix. The high-quality welds were successfully produced with optimised welding parameters, and studied by means of optical microscopy (OM), scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD) and standard hardness and impact toughness testing. The results show that microstructure and mechanical properties of the joints are affected greatly, which is mainly related to the remarkably fine-grained microstructure of equiaxed ferrite that is observed in the friction stir welded joint. Meanwhile, the ratios of low-angle grain boundary in the stir zone regions significantly increase, and the texture turns strong. Compared with the base material, mechanical properties of the joint are maintained in a comparatively high level

  2. A bottom-up approach for optimization of friction stir processing parameters; a study on aluminium 2024-T3 alloy

    International Nuclear Information System (INIS)

    Nadammal, Naresh; Kailas, Satish V.; Suwas, Satyam

    2015-01-01

    Highlights: • An experimental bottom-up approach has been developed for optimizing the process parameters for friction stir processing. • Optimum parameter processed samples were tested and characterized in detail. • Ultimate tensile strength of 1.3 times the base metal strength was obtained. • Residual stresses on the processed surface were only 10% of the yield strength of base metal. • Microstructure observations revealed fine equi-axed grains with precipitate particles at the grain boundaries. - Abstract: Friction stir processing (FSP) is emerging as one of the most competent severe plastic deformation (SPD) method for producing bulk ultra-fine grained materials with improved properties. Optimizing the process parameters for a defect free process is one of the challenging aspects of FSP to mark its commercial use. For the commercial aluminium alloy 2024-T3 plate of 6 mm thickness, a bottom-up approach has been attempted to optimize major independent parameters of the process such as plunge depth, tool rotation speed and traverse speed. Tensile properties of the optimum friction stir processed sample were correlated with the microstructural characterization done using Scanning Electron Microscope (SEM) and Electron Back-Scattered Diffraction (EBSD). Optimum parameters from the bottom-up approach have led to a defect free FSP having a maximum strength of 93% the base material strength. Micro tensile testing of the samples taken from the center of processed zone has shown an increased strength of 1.3 times the base material. Measured maximum longitudinal residual stress on the processed surface was only 30 MPa which was attributed to the solid state nature of FSP. Microstructural observation reveals significant grain refinement with less variation in the grain size across the thickness and a large amount of grain boundary precipitation compared to the base metal. The proposed experimental bottom-up approach can be applied as an effective method for

  3. Characteristics of Friction Stir Processed UHMW Polyethylene Based Composite

    Science.gov (United States)

    Hussain, G.; Khan, I.

    2018-01-01

    Ultra-high molecular weight polyethylene (UHMWPE) based composites are widely used in biomedical and food industries because of their biocompatibility and enhanced properties. The aim of this study was to fabricate UHMWPE / nHA composite through heat assisted Friction Stir Processing. The rotational speed (ω), feed rate (f), volume fraction of nHA (v) and shoulder temperature (T) were selected as the process parameters. Macroscopic and microscopic analysis revealed that these parameters have significant effects on the distribution of reinforcing material, defects formation and material mixing. Defects were observed especially at low levels of (ω, T) and high levels of (f, v). Low level of v with medium levels of other parameters resulted in better mixing and minimum defects. A 10% increase in strength with only 1% reduction in Percent Elongation was observed at the above set of conditions. Moreover, the resulted hardness of the composite was higher than that of the parent material.

  4. Fabrication of Al5083 surface composites reinforced by CNTs and cerium oxide nano particles via friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, S.A. [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz (Iran, Islamic Republic of); Ranjbar, Khalil, E-mail: k_ranjbar@scu.ac.ir [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz (Iran, Islamic Republic of); Dehmolaei, R. [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz (Iran, Islamic Republic of); Amirani, A.R. [12th Ghaem Street, Bld. Hashemzadeh, Shahrak Golestan, Tehran (Iran, Islamic Republic of)

    2015-02-15

    Highlights: • Using friction stir processing, an effect of CNTs and CeO{sub 2} reinforcements on mechanical and corrosion properties of Al5083 alloy is reported. • The strength of Al5083 was increased by 42%, its matrix grain size reduced five times, and hardness was doubled by the incorporation of CNTs-CeO{sub 2} mixture in the volume ratio of 75-25 respectively. • Unlike the CNTs, incorporation of nanosized CeO{sub 2} particles resulted in remarkable increase in pitting resistance of the alloy. - Abstract: In the present investigation, friction stir processing (FSP) was utilized to incorporate Multi Walled Carbon Nano Tubes (MWCNT) and nanosized cerium oxide particles into the matrix of Al5083 alloy to form surface reinforced composites. The effect of these nanosized reinforcements either separately or in the combined form, on microstructural modification, mechanical properties and corrosion resistance of FSPed Al5083 surface composites was studied. A threaded cylindrical hardened steel tool was used with the rotation speeds of 600 and 800 rpm and travel speeds of 35 and 45 mm/min and a tilt angle of 5°. Mechanical properties and corrosion resistance of FSPed samples were evaluated and compared with the base alloy. The maximum tensile strength and hardness value were achieved for the hybrid composite containing a mixture of CNTs and cerium oxide in the volume ratio of 75-25, respectively, whereas a significant increase in pitting resistance of the base alloy was obtained when cerium oxide alone was incorporated. The corrosion behavior of the samples was investigated by potentiodynamic polarization tests and assessed in term of pitting potential and passivation range. Microstructural analysis carried out by using optical and electron microscopes showed that reinforcements are well dispersed inside the nugget zone (NZ), and remarkable grain refinement is gained. The study was aimed to fabricate surface composites with improved mechanical properties and

  5. Mechanical properties and fracture behaviour of ODS steel friction stir welds at variable temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, H., E-mail: huwdawson@gmail.com [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Serrano, M.; Hernandez, R. [Structural Materials Division, Technology Department, CIEMAT, Avda de la Complutense 40, 28040 Madrid (Spain); Cater, S. [Friction and Forge Processes Department, Joining Technologies Group, TWI Technology Centre (Yorkshire), Advanced Manufacturing Park, Wallis Way, Catcliffe, Rotherham S60 5TZ (United Kingdom); Jimenez-Melero, E. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom)

    2017-05-02

    We have assessed the microstructure and the temperature-dependent mechanical behaviour of five bead-on-plate friction stir welds of Oxide Dispersion Strengthened (ODS) steel, produced using systematic changes to the tool rotation and traverse speed. Friction stir welding can potentially retain the fine dispersion of nanoparticles, and therefore also the high-temperature strength and radiation damage resistance of these materials. Tensile testing was carried out on the MA956 base material at a range of temperatures, from room temperature up to 750 °C. The mechanical properties of the welds were investigated via tensile testing at room temperature and at 500 °C, together with micro-hardness testing. The welds exhibited similar strength and ductility to the base material at both testing temperatures as welding caused a partial loss of particle strengthening, alongside an increase in grain boundary strengthening due to a greatly refined grain size in the stir zones. The micro-hardness data revealed a trend of increasing hardness with increasing tool traverse speed or decreasing rotation speed. This was attributed to the smaller grain size and lower nanoparticle number density in the welds created with these parameters. At 500 °C, the yield stress and ultimate tensile stress of the base material and the welds decreased, due to a progressive reduction in both the Orowan-type particle strengthening and the grain boundary strengthening.

  6. Parallel processing method for high-speed real time digital pulse processing for gamma-ray spectroscopy

    International Nuclear Information System (INIS)

    Fernandes, A.M.; Pereira, R.C.; Sousa, J.; Neto, A.; Carvalho, P.; Batista, A.J.N.; Carvalho, B.B.; Varandas, C.A.F.; Tardocchi, M.; Gorini, G.

    2010-01-01

    A new data acquisition (DAQ) system was developed to fulfil the requirements of the gamma-ray spectrometer (GRS) JET-EP2 (joint European Torus enhancement project 2), providing high-resolution spectroscopy at very high-count rate (up to few MHz). The system is based on the Advanced Telecommunications Computing Architecture TM (ATCA TM ) and includes a transient record (TR) module with 8 channels of 14 bits resolution at 400 MSamples/s (MSPS) sampling rate, 4 GB of local memory, and 2 field programmable gate array (FPGA) able to perform real time algorithms for data reduction and digital pulse processing. Although at 400 MSPS only fast programmable devices such as FPGAs can be used either for data processing and data transfer, FPGA resources also present speed limitation at some specific tasks, leading to an unavoidable data lost when demanding algorithms are applied. To overcome this problem and foreseeing an increase of the algorithm complexity, a new digital parallel filter was developed, aiming to perform real time pulse processing in the FPGAs of the TR module at the presented sampling rate. The filter is based on the conventional digital time-invariant trapezoidal shaper operating with parallelized data while performing pulse height analysis (PHA) and pile up rejection (PUR). The incoming sampled data is successively parallelized and fed into the processing algorithm block at one fourth of the sampling rate. The following data processing and data transfer is also performed at one fourth of the sampling rate. The algorithm based on data parallelization technique was implemented and tested at JET facilities, where a spectrum was obtained. Attending to the observed results, the PHA algorithm will be improved by implementing the pulse pile up discrimination.

  7. A semelparous fish continues upstream migration when exposed to alarm cue, but adjusts movement speed and timing

    Science.gov (United States)

    Luhring, Thomas M; Meckley, Trevor D.; Johnson, Nicholas S.; Siefkes, Michael J.; Hume, John B.; Wagner, C. Michael

    2016-01-01

    Animals make trade-offs between predation risk and pursuit of opportunities such as foraging and reproduction. Trade-offs between antipredator behaviours and foraging are well suited to manipulation in laboratory and field settings and have generated a vast compendium of knowledge. However, much less is known about how animals manage trade-offs between predation risk and pursuit of reproductive opportunities in the absence of the confounding effects of foraging. In the present study, we investigated how the nonfeeding migratory life stage of sea lamprey, Petromyzon marinus, responds to odour from dead conspecifics (a cue that induces avoidance behaviours in laboratory and field studies). We released groups of PIT-tagged sea lamprey 65 m from the shore of Lake Michigan or 287 m upstream in Carp Lake River and used antennas to detect their movements in the river. As the breeding season progressed, sea lamprey initiated upstream movement earlier and were more likely to enter the river. Sea lamprey that began the night in Lake Michigan entered Carp Lake River at higher rates and accelerated upstream when exposed to high concentrations of alarm cue, consistent with animals attempting to minimize time spent in risky areas. Sea lampreys that began the night in the river delayed upstream movement when exposed to alarm cue, consistent with animals sheltering and gathering information about a source of risk. We attribute this context-specific reaction to alarm cue to differences in perceived vulnerability to predation in sheltered positions in the river versus exposed positions in the lake. Once in the river, the vast majority of sea lamprey moved upstream independent of alarm cue or Julian date. Although life-history-induced time and energy budgets place rigid constraints on the direction of migration, sea lamprey attend to predation risk by modifying movement timing and speed.

  8. An Improved Continuous-Time Model Predictive Control of Permanent Magnetic Synchronous Motors for a Wide-Speed Range

    Directory of Open Access Journals (Sweden)

    Dandan Su

    2017-12-01

    Full Text Available This paper proposes an improved continuous-time model predictive control (CTMPC of permanent magnetic synchronous motors (PMSMs for a wide-speed range, including the constant torque region and the flux-weakening (FW region. In the constant torque region, the mathematic models of PMSMs in dq-axes are decoupled without the limitation of DC-link voltage. However, in the FW region, the mathematic models of PMSMs in dq-axes are cross-coupled together with the limitation of DC-link voltage. A nonlinear PMSMs mathematic model in the FW region is presented based on the voltage angle. The solving of the nonlinear mathematic model of PMSMs in FW region will lead to heavy computation load for digital signal processing (DSP. To overcome such a problem, a linearization method of the voltage angle is also proposed to reduce the computation load. The selection of transiting points between the constant torque region and FW regions is researched to improve the performance of the driven system. Compared with the proportional integral (PI controller, the proposed CTMPC has obvious advantages in dealing with systems’ nonlinear constraints and improving system performance by restraining overshoot current under step torque changing. Both simulation and experimental results confirm the effectiveness of the proposed method in achieving good steady-state performance and smooth switching between the constant torque and FW regions.

  9. Introducing a new and rapid microextraction approach based on magnetic ionic liquids: Stir bar dispersive liquid microextraction

    International Nuclear Information System (INIS)

    Chisvert, Alberto; Benedé, Juan L.; Anderson, Jared L.; Pierson, Stephen A.; Salvador, Amparo

    2017-01-01

    With the aim of contributing to the development and improvement of microextraction techniques, a novel approach combining the principles and advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) is presented. This new approach, termed stir bar dispersive liquid microextraction (SBDLME), involves the addition of a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar into the sample allowing the MIL coat the stir bar due to physical forces (i.e., magnetism). As long as the stirring rate is maintained at low speed, the MIL resists rotational (centrifugal) forces and remains on the stir bar surface in a manner closely resembling SBSE. By increasing the stirring rate, the rotational forces surpass the magnetic field and the MIL disperses into the sample solution in a similar manner to DLLME. After extraction, the stirring is stopped and the MIL returns to the stir bar without the requirement of an additional external magnetic field. The MIL-coated stir bar containing the preconcentrated analytes is thermally desorbed directly into a gas chromatographic system coupled to a mass spectrometric detector (TD-GC-MS). This novel approach opens new insights into the microextraction field, by using the benefits provided by SBSE and DLLME simultaneously, such as automated thermal desorption and high surface contact area, respectively, but most importantly, it enables the use of tailor-made solvents (i.e., MILs). To prove its utility, SBDLME has been used in the extraction of lipophilic organic UV filters from environmental water samples as model analytical application with excellent analytical features in terms of linearity, enrichment factors (67–791), limits of detection (low ng L −1 ), intra- and inter-day repeatability (RSD<15%) and relative recoveries (87–113%, 91–117% and 89–115% for river, sea and swimming pool water samples, respectively). - Highlights: • A new microextraction method combining the

  10. The study on defects in aluminum 2219-T6 thick butt friction stir welds with the application of multiple non-destructive testing methods

    International Nuclear Information System (INIS)

    Li, Bo; Shen, Yifu; Hu, Weiye

    2011-01-01

    Research highlights: → Friction stir weld-defect forming mechanisms of thick butt-joints. → Relationship between weld-defects and friction stir welding process parameters. → Multiple non-destructive testing methods applied to friction stir welds. → Empirical criterion basing on mass-conservation for inner material-loss defects. → Nonlinear correlation between weld strengths and root-flaw lengths. -- Abstract: The present study focused on the relationship between primary friction stir welding process parameters and varied types of weld-defect discovered in aluminum 2219-T6 friction stir butt-welds of thick plates, meanwhile, the weld-defect forming mechanisms were investigated. Besides a series of optical metallographic examinations for friction stir butt welds, multiple non-destructive testing methods including X-ray detection, ultrasonic C-scan testing, ultrasonic phased array inspection and fluorescent penetrating fluid inspection were successfully used aiming to examine the shapes and existence locations of different weld-defects. In addition, precipitated Al 2 Cu phase coarsening particles were found around a 'kissing-bond' defect within the weld stirred nugget zone by means of scanning electron microscope and energy dispersive X-ray analysis. On the basis of volume conservation law in material plastic deformation, a simple empirical criterion for estimating the existence of inner material-loss defects was proposed. Defect-free butt joints were obtained after process optimization of friction stir welding for aluminum 2219-T6 plates in 17-20 mm thickness. Process experiments proved that besides of tool rotation speed and travel speed, more other appropriate process parameter variables played important roles at the formation of high-quality friction stir welds, such as tool-shoulder target depth, spindle tilt angle, and fixture clamping conditions on the work-pieces. Furthermore, the nonlinear correlation between weld tensile strengths and weld crack

  11. Optimization of friction stir welding process parameters to maximize tensile strength of stir cast AA6061-T6/AlNp composite

    International Nuclear Information System (INIS)

    Ashok Kumar, B.; Murugan, N.

    2014-01-01

    Highlights: • AA6061/AlN p cast composite was welded by FSW process. • Regression models were developed to predict UTS and elongation of the FS welded joint. • FS welded joint using the optimized parameters exhibited maximum UTS and joint efficiency. • Defect free weld joint was obtained with optimized parameters value. - Abstract: Aluminium Matrix Composites (AMCs) reinforced with particulate form of reinforcement has replaced monolithic alloys in many engineering industries due to its superior mechanical properties and tailorable thermal and electrical properties. As aluminium nitride (AlN) has high specific strength, high thermal conductivity, high electrical resistivity, low dielectric constant, low coefficient of thermal expansion and good compatibility with aluminium alloy, Al/AlN composite is extensively used in electronic packaging industries. Joining of AMCs is unavoidable in many engineering applications. Friction Stir Welding (FSW) is one of the most suitable welding process to weld the AMCs reinforced with particulate form of ceramics without deteriorating its superior mechanical properties. An attempt has been made to develop regression models to predict the Ultimate Tensile Strength (UTS) and Percent Elongation (PE) of the friction stir welded AA6061 matrix composite reinforced with aluminium nitride particles (AlN p ) by correlating the significant parameters such as tool rotational speed, welding speed, axial force and percentage of AlN p reinforcement in the AA6061 matrix. Statistical software SYSTAT 12 and statistical tools such as analysis of variance (ANOVA) and student’s t test, have been used to validate the developed models. It was observed from the investigation that these factors independently influenced the UTS and PE of the friction stir welded composite joints. The developed regression models were optimized to maximize UTS of friction stir welded AA6061/AlN p composite joints

  12. In-situ neutron diffraction measurements of temperature and stresses during friction stir welding of 6061-T6 aluminum alloy

    International Nuclear Information System (INIS)

    Woo, Wan Chuck; Feng, Zhili; Wang, Xun-Li; Brown, D.W.; Clausen, B.; An, Ke; Choo, Hahn; Hubbard, Camden R.; David, Stan A.

    2007-01-01

    The evolution of temperature and thermal stresses during friction stir welding of Al6061-T6 was investigated by means of in-situ, time-resolved neutron diffraction technique. A method is developed to deconvolute the temperature and stress from the lattice spacing changes measured by neutron diffraction. The deep penetration capability of neutrons made it possible for the first time to obtain the temperature and thermal stresses inside a friction stir weld

  13. Surface hardening of two cast irons by friction stir processing

    International Nuclear Information System (INIS)

    Fujii, Hidetoshi; Kikuchi, Toshifumi; Nogi, Kiyoshi; Yamaguchi, Yasufumi; Kiguchi, Shoji

    2009-01-01

    The Friction Stir Processing (FSP) was applied to the surface hardening of cast irons. Flake graphite cast iron (FC300) and nodular graphite cast iron (FCD700) were used to investigate the validity of this method. The matrices of the FC300 and FC700 cast irons are pearlite. The rotary tool is a 25mm diameter cylindrical tool, and the travelling speed was varied between 50 and 150mm/min in order to control the heat input at the constant rotation speed of 900rpm. As a result, it has been clarified that a Vickers hardness of about 700HV is obtained for both cast irons. It is considered that a very fine martensite structure is formed because the FSP generates the heat very locally, and a very high cooling rate is constantly obtained. When a tool without an umbo (probe) is used, the domain in which graphite is crushed and striated is minimized. This leads to obtaining a much harder sample. The hardness change depends on the size of the martensite, which can be controlled by the process conditions, such as the tool traveling speed and the load. Based on these results, it was clarified that the FSP has many advantages for cast irons, such as a higher hardness and lower distortion. As a result, no post surface heat treatment and no post machining are required to obtain the required hardness, while these processes are generally required when using the traditional methods.

  14. Prediction of mechanical properties in friction stir welds of pure copper

    International Nuclear Information System (INIS)

    Heidarzadeh, A.; Saeid, T.

    2013-01-01

    Highlights: • Range of parameters for defect-free friction stir welded pure copper was reached. • Models were developed for predicting UTS, TE and hardness of pure copper joints. • Analysis of variance was used to validate the developed models. • Effect of welding parameters on mechanical behavior of welded joints was explored. • The microstructure and fracture surface of welded joints were investigated. - Abstract: This research was carried out to predict the mechanical properties of friction stir welded pure copper joints. Response surface methodology based on a central composite rotatable design with three parameters, five levels, and 20 runs, was used to conduct the experiments and to develop the mathematical regression model by using of Design-Expert software. The three welding parameters considered were rotational speed, welding speed, and axial force. Analysis of variance was applied to validate the predicted models. Microstructural characterization and fractography of joints were examined using optical and scanning electron microscopes. Also, the effects of the welding parameters on mechanical properties of friction stir welded joints were analyzed in detail. The results showed that the developed models were reasonably accurate. The increase in welding parameters resulted in increasing of tensile strength of the joints up to a maximum value. Elongation percent of the joints increased with increase of rotational speed and axial force, but decreased by increasing of welding speed, continuously. In addition, hardness of the joints decreased with increase of rotational speed and axial force, but increased by increasing of welding speed. The joints welded at higher heat input conditions revealed more ductility fracture mode

  15. Turbulence modeling of the Von Karman flow: Viscous and inertial stirrings

    International Nuclear Information System (INIS)

    Poncet, Sebastien; Schiestel, Roland; Monchaux, Romain

    2008-01-01

    The present work considers the turbulent Von Karman flow generated by two counter-rotating smooth flat (viscous stirring) or bladed (inertial stirring) disks. Numerical predictions based on one-point statistical modeling using a low-Reynolds number second-order full stress transport closure (RSM model) are compared to velocity measurements performed at CEA (Commissariat a l'Energie Atomique, France). The main and significant novelty of this paper is the use of a drag force in the momentum equations to reproduce the effects of inertial stirring instead of modeling the blades themselves. The influences of the rotational Reynolds number, the aspect ratio of the cavity, the rotating disk speed ratio and of the presence or not of impellers are investigated to get a precise knowledge of both the dynamics and the turbulence properties in the Von Karman configuration. In particular, we highlighted the transition between the merged and separated boundary layer regimes and the one between the Batchelor [Batchelor, G.K., 1951. Note on a class of solutions of the Navier-Stokes equations representing steady rotationally-symmetric flow. Quat. J. Mech. Appl. Math. 4 (1), 29-41] and the Stewartson [Stewartson, K., 1953. On the flow between two rotating coaxial disks. Proc. Camb. Philos. Soc. 49, 333-341] flow structures in the smooth disk case. We determined also the transition between the one cell and the two cell regimes for both viscous and inertial stirrings

  16. Correlations between aorto-popliteal bolus transit speed and aortic and popliteal bolus transit time during CT angiography of aortoiliac and lower extremity arteries

    Energy Technology Data Exchange (ETDEWEB)

    Nakaya, Yasuhiro, E-mail: y-nakaya@radiol.med.osaka-u.ac.jp [Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita City, Osaka 565-0871 (Japan); Kim, Tonsok; Hori, Masatoshi; Onishi, Hiromitsu; Nakamoto, Atsushi; Tsuboyama, Takahiro; Maeda, Noboru; Higashihara, Hiroki; Tomoda, Kaname; Nakamura, Hironobu [Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita City, Osaka 565-0871 (Japan)

    2011-08-15

    Purpose: The purpose of this study was to investigate correlations between the aorto-popliteal bolus transit speed and aortic and popliteal bolus transit time in order to evaluate the possibility for prediction of bolus transit speed by single test injection technique. Materials and methods: Approval was obtained from our institutional review board for this study, which included 42 patients, from all of whom written informed consent was obtained. Low-dose serial CT scanning after injection of 12 ml contrast material (300 mg/ml) at a rate of 3 ml/s followed by saline flush was performed twice, first at the level of the upper abdomen and second at the level of the knee joint. The times needed to reach peak enhancement of the upper abdominal aorta (T-aorta) and bilateral popliteal arteries (T-popliteal) were obtained, and aorto-popliteal bolus transit speeds between the abdominal aorta and popliteal arteries were calculated. ABI was recorded for the bilateral feet. The Pearson's product-moment correlation coefficient was used to investigate the correlation between the bolus transit speed and T-aorta, T-popliteal, ABI, and patient age. Result: The respective correlation coefficients for bolus transit speed on the one hand and T-aorta, T-popliteal, ABI, patient age on the other were -0.50, -0.84, 0.36, and -0.52. Conclusion: The time to peak enhancement for popliteal arteries showed the strongest correlation with aorto-popliteal bolus transit speeds, and was considered to be the most accurate predictor for aorto-popliteal bolus transit speeds.

  17. Maximum swimming speeds of sailfish and three other large marine predatory fish species based on muscle contraction time and stride length: a myth revisited

    Directory of Open Access Journals (Sweden)

    Morten B. S. Svendsen

    2016-10-01

    Full Text Available Billfishes are considered to be among the fastest swimmers in the oceans. Previous studies have estimated maximum speed of sailfish and black marlin at around 35 m s−1 but theoretical work on cavitation predicts that such extreme speed is unlikely. Here we investigated maximum speed of sailfish, and three other large marine pelagic predatory fish species, by measuring the twitch contraction time of anaerobic swimming muscle. The highest estimated maximum swimming speeds were found in sailfish (8.3±1.4 m s−1, followed by barracuda (6.2±1.0 m s−1, little tunny (5.6±0.2 m s−1 and dorado (4.0±0.9 m s−1; although size-corrected performance was highest in little tunny and lowest in sailfish. Contrary to previously reported estimates, our results suggest that sailfish are incapable of exceeding swimming speeds of 10-15 m s−1, which corresponds to the speed at which cavitation is predicted to occur, with destructive consequences for fin tissues.

  18. Microstructural evolution during friction stir welding of AlSi1MgMn alloy

    Directory of Open Access Journals (Sweden)

    M. Janjić

    2012-01-01

    Full Text Available This paper provides the research of the infl uence of geometric and kinematic parameters on the microstructure and mechanical properties of welded joint of aluminum alloy AlSi1MgMn (6082-T6 obtained through the Friction Stir Welding (FSW process. The experiment parameters were welding speed, rotation speed, angle of pin slope, pin diameter and shoulder diameter. On the obtained welded workpieces the dynamic testing on the impact toughness, and determination of microstructural zones were carried out.

  19. Multi-objective Optimization of Process Parameters in Friction Stir Welding

    DEFF Research Database (Denmark)

    Tutum, Cem Celal; Hattel, Jesper Henri

    The objective of this paper is to investigate optimum process parameters in Friction Stir Welding (FSW) to minimize residual stresses in the work piece and maximize production efficiency meanwhile satisfying process specific constraints as well. More specifically, the choices of tool rotational...... speed and traverse welding speed have been sought in order to achieve the goals mentioned above using an evolutionary multi-objective optimization (MOO) algorithm, i.e. non-dominated sorting genetic algorithm (NSGA-II), integrated with a transient, 2- dimensional sequentially coupled thermo...

  20. Microscopic analysis of the morphology of seams in friction stir welded polypropylene

    Directory of Open Access Journals (Sweden)

    Z. Kiss

    2012-01-01

    Full Text Available Supermolecular structure of welded seams prepared by friction stir welding (FSW of polypropylene sheets has been studied by optical and electron microscopy. It has been shown that in the central parts of the seam spherulitic structures similar to that of the base material are formed, while at the borderline of the seam, a complex supermolecular structure could be identified. Lower welding rotation speed resulted in a border transition zone of more complex feature than the higher rotation speed during FSW. This was accompanied by reduced joint efficiency.

  1. Pitting corrosion of friction stir welded aluminum alloy thick plate in alkaline chloride solution

    International Nuclear Information System (INIS)

    Xu Weifeng; Liu Jinhe; Zhu Hongqiang

    2010-01-01

    The pitting corrosion of different positions (Top, Middle and Bottom) of weld nugget zone (WNZ) along thickness plate in friction stir welded 2219-O aluminum alloy in alkaline chloride solution was investigated by using open circuit potential, cyclic polarization, scanning electron microscopy and atomic force microscope. The results indicate that the material presents significant passivation, the top has highest corrosion potential, pitting potential and re-passivation potential compared with the bottom and base material. With the increase of traverse speed from 60 to 100 mm/min or rotary speed from 500 to 600 rpm, the corrosion resistance decreases.

  2. Ultrasonic Stir Welding Development for Ground-Based and In Situ Fabrication and Repair for In-Space Propulsion Systems/Commercial Space Sector

    Science.gov (United States)

    Ding, Jeff

    2015-01-01

    The completed Center Innovation Fund (CIF) project used the upgraded Ultrasonic Stir Weld (USW) Prototype System (built in 2013/2014) to begin characterizing the weld process using 2219 aluminum (fig. 1). This work is being done in Bldg. 4755 at NASA Marshall Space Flight Center (MSFC). The capabilities of the USW system provides the means to precisely control and document individual welding parameters. The current upgraded system has the following capabilities: (1) Ability to 'pulse' ultrasonic (US) energy on and off and adjust parameters real-time (travel speed, spindle rpm, US amplitude, X and Z axis positions, and plunge and pin axis force; (2) Means to measure draw force; (3) Ability to record US power versus time; (4) Increasing stiffness of Z axis drive and reduce head deflection using laser technology; (5) Adding linear encoder to better control tool penetration setting; (6) Ultrasonic energy integrated into stir rod and containment plate; (7) Maximum 600 rpm; (8) Maximum Z force 15,000 lb; (9) Real-time data acquisition and logging capabilities at a minimum frequency of 10 Hz; and (10) Two separate transducer power supplies operating at 4.5 kW power.

  3. Passenger Sharing of the High-Speed Railway from Sensitivity Analysis Caused by Price and Run-time Based on the Multi-Agent System

    Directory of Open Access Journals (Sweden)

    Ma Ning

    2013-09-01

    Full Text Available Purpose: Nowadays, governments around the world are active in constructing the high-speed railway. Therefore, it is significant to make research on this increasingly prevalent transport.Design/methodology/approach: In this paper, we simulate the process of the passenger’s travel mode choice by adjusting the ticket fare and the run-time based on the multi-agent system (MAS.Findings: From the research we get the conclusion that increasing the run-time appropriately and reducing the ticket fare in some extent are effective ways to enhance the passenger sharing of the high-speed railway.Originality/value: We hope it can provide policy recommendations for the railway sectors in developing the long-term plan on high-speed railway in the future.

  4. Stirring the Ashes of Public Discourse.

    Science.gov (United States)

    Marinara, Martha

    Sylvia Plath's confessional poem, "Lady Lazarus" can be used to illustrate a connection between autobiography and social critique. "You poke and stir" among the institutions that form social relations--the educational system, the court system, the economic system--to find individuals whose lives, whose joys and pains, and…

  5. Time Series Analysis and Forecasting for Wind Speeds Using Support Vector Regression Coupled with Artificial Intelligent Algorithms

    Directory of Open Access Journals (Sweden)

    Ping Jiang

    2015-01-01

    Full Text Available Wind speed/power has received increasing attention around the earth due to its renewable nature as well as environmental friendliness. With the global installed wind power capacity rapidly increasing, wind industry is growing into a large-scale business. Reliable short-term wind speed forecasts play a practical and crucial role in wind energy conversion systems, such as the dynamic control of wind turbines and power system scheduling. In this paper, an intelligent hybrid model for short-term wind speed prediction is examined; the model is based on cross correlation (CC analysis and a support vector regression (SVR model that is coupled with brainstorm optimization (BSO and cuckoo search (CS algorithms, which are successfully utilized for parameter determination. The proposed hybrid models were used to forecast short-term wind speeds collected from four wind turbines located on a wind farm in China. The forecasting results demonstrate that the intelligent hybrid models outperform single models for short-term wind speed forecasting, which mainly results from the superiority of BSO and CS for parameter optimization.

  6. Effects of interactive metronome training on timing, attention, working memory, and processing speed in children with ADHD: a case study of two children.

    Science.gov (United States)

    Park, Yun-Yi; Choi, Yu-Jin

    2017-12-01

    [Purpose] The purpose of this study was to present the effects of Interactive metronome (IM) on timing for children with Attention-Deficit Hyperactivity Disorder (ADHD). [Subjects and Methods] The subjects of the present study were 2 children diagnosed with ADHD. Pre- and post-intervention tests were completed by the researcher using Long Form Assessment (LFA) test of IM and K-WPPSI-IV. The subjects were provided with IM for 40 minutes at a time, 2 times per week, for a total of 8 weeks. [Results] The timing decreased after IM intervention. The subjects showed improvement in attention span after IM intervention. Working memory index as well as processing speed index were increased after intervention, as shown by the Korean-Wechsler Preschool and Primary Scale of Intelligence-IV (K-WPPSI-IV). [Conclusion] IM was effective in improving timing, attention, working memory and processing speed in children with ADHD.

  7. Modeling and simulation of soft sensor design for real-time speed estimation, measurement and control of induction motor.

    Science.gov (United States)

    Etien, Erik

    2013-05-01

    This paper deals with the design of a speed soft sensor for induction motor. The sensor is based on the physical model of the motor. Because the validation step highlight the fact that the sensor cannot be validated for all the operating points, the model is modified in order to obtain a fully validated sensor in the whole speed range. An original feature of the proposed approach is that the modified model is derived from stability analysis using automatic control theory. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

  8. Design of FPGA based high-speed data acquisition and real-time data processing system on J-TEXT tokamak

    International Nuclear Information System (INIS)

    Zheng, W.; Liu, R.; Zhang, M.; Zhuang, G.; Yuan, T.

    2014-01-01

    Highlights: • It is a data acquisition system for polarimeter–interferometer diagnostic on J-TEXT tokamak based on FPGA and PXIe devices. • The system provides a powerful data acquisition and real-time data processing performance. • Users can implement different data processing applications on the FPGA in a short time. • This system supports EPICS and has been integrated into the J-TEXT CODAC system. - Abstract: Tokamak experiment requires high-speed data acquisition and processing systems. In traditional data acquisition system, the sampling rate, channel numbers and processing speed are limited by bus throughput and CPU speed. This paper presents a data acquisition and processing system based on FPGA. The data can be processed in real-time before it is passed to the CPU. It provides processing ability for more channels with higher sampling rates than the traditional data acquisition system while ensuring deterministic real-time performance. A working prototype is developed for the newly built polarimeter–interferometer diagnostic system on the Joint Texas Experimental Tokamak (J-TEXT). It provides 16 channels with 120 MHz maximum sampling rate and 16 bit resolution. The onboard FPGA is able to calculate the plasma electron density and Faraday rotation angel. A RAID 5 storage device is adopted providing 700 MB/s read–write speed to buffer the data to the hard disk continuously for better performance

  9. Thermal Stir Welding: A New Solid State Welding Process

    Science.gov (United States)

    Ding, R. Jeffrey

    2003-01-01

    Thermal stir welding is a new welding process developed at NASA's Marshall Space Flight Center in Huntsville, AL. Thermal stir welding is similar to friction stir welding in that it joins similar or dissimilar materials without melting the parent material. However, unlike friction stir welding, the heating, stirring and forging elements of the process are all independent of each other and are separately controlled. Furthermore, the heating element of the process can be either a solid-state process (such as a thermal blanket, induction type process, etc), or, a fusion process (YG laser, plasma torch, etc.) The separation of the heating, stirring, forging elements of the process allows more degrees of freedom for greater process control. This paper introduces the mechanics of the thermal stir welding process. In addition, weld mechanical property data is presented for selected alloys as well as metallurgical analysis.

  10. Interfacial Microstructure and Mechanical Properties of Friction Stir Welded Joints of Commercially Pure Aluminum and 304 Stainless Steel

    Science.gov (United States)

    Murugan, Balamagendiravarman; Thirunavukarasu, Gopinath; Kundu, Sukumar; Kailas, Satish V.; Chatterjee, Subrata

    2018-05-01

    In the present investigation, friction stir welding of commercially pure aluminum and 304 stainless steel was carried out at varying tool rotational speeds from 200 to 1000 rpm in steps of 200 rpm using 60 mm/min traverse speed at 2 (degree) tool tilt angle. Microstructural characterization of the interfacial zone was carried out using optical microscope and scanning electron microscope. Energy-dispersive spectroscopy indicated the presence of FeAl3 intermetallic phase. Thickness of the intermetallic layer increased with the increase in tool rotational speed. X-ray diffraction studies indicated the formation of intermetallic phases like FeAl2, Fe4Al13, Fe2Al5, and FeAl3. A maximum tensile strength of 90% that of aluminum along with 4.5% elongation was achieved with the welded sample at tool rotational speed of 400 rpm. The stir zone showed higher hardness as compared to base metals, heat affected zone, and thermo-mechanically affected zone due to the presence of intermetallics. The maximum hardness value at the stir zone was achieved at 1000 rpm tool rotational speed.

  11. A fundamental study on the structural integrity of magnesium alloys joined by friction stir welding

    Science.gov (United States)

    Rao, Harish Mangebettu

    The goal of this research is to study the factors that influence the physical and mechanical properties of lap-shear joints produced using friction stir welding. This study focuses on understanding the effect of tool geometry and weld process parameters including the tool rotation rate, tool plunge depth and dwell time on the mechanical performance of similar magnesium alloy and dissimilar magnesium to aluminum alloy weld joints. A variety of experimental activities were conducted including tensile and fatigue testing, fracture surface and failure analysis, microstructure characterization, hardness measurements and chemical composition analysis. An investigation on the effect of weld process conditions in friction stir spot welding of magnesium to magnesium produced in a manner that had a large effective sheet thickness and smaller interfacial hook height exhibited superior weld strength. Furthermore, in fatigue testing of friction stir spot welded of magnesium to magnesium alloy, lap-shear welds produced using a triangular tool pin profile exhibited better fatigue life properties compared to lap-shear welds produced using a cylindrical tool pin profile. In friction stir spot welding of dissimilar magnesium to aluminum, formation of intermetallic compounds in the stir zone of the weld had a dominant effect on the weld strength. Lap-shear dissimilar welds with good material mixture and discontinues intermetallic compounds in the stir zone exhibited superior weld strength compared to lap-shear dissimilar welds with continuous formation of intermetallic compounds in the stir zone. The weld structural geometry like the interfacial hook, hook orientation and bond width also played a major role in influencing the weld strength of the dissimilar lap-shear friction stir spot welds. A wide scatter in fatigue test results was observed in friction stir linear welds of aluminum to magnesium alloys. Different modes of failure were observed under fatigue loading including crack

  12. Investigation of the material flow and texture evolution in friction-stir welded aluminum alloy

    Science.gov (United States)

    Kang, Suk Hoon; Han, Heung Nam; Oh, Kyu Hwan; Cho, Jae-Hyung; Lee, Chang Gil; Kim, Sung-Joon

    2009-12-01

    The material flow and crystallographic orientation in aluminum alloy sheets joined by friction stir welding (FSW) were investigated by electron back scattered diffraction (EBSD). The microstructure and microtexture of the material near the stir zone was found to be influenced by the rotational behavior of the tool pin. It was found that, during FSW, the forward movement of the tool pin resulted in loose contact between the tool pin and the receding material at the advancing side. This material behavior inside the joined aluminum plates was also observed by an X-ray micrograph by inlaying a gold marker into the plates. As the advancing speed of the tool increases at a given rotation speed, the loose contact region widens. As the microtexture of the material near the stir zone is very close to the simple shear texture on the basis of the frame of the tool pin in the normal and tangent directions, the amount of incompletely rotated material due to the loose contact could be estimated from the tilt angle of the shear texture in the pole figure around the key hole.

  13. INVESTIGATION OF SINGLE-PASS/DOUBLE-PASS TECHNIQUES ON FRICTION STIR WELDING OF ALUMINIUM

    Directory of Open Access Journals (Sweden)

    N.A.A. Sathari

    2014-12-01

    Full Text Available The aim of this research is to study the effects of single-pass/ double-pass techniques on friction stir welding of aluminium. Two pieces of AA1100 with a thickness of 6.0 mm were friction stir welded using a CNC milling machine at rotational speeds of 1400 rpm, 1600 rpm and 1800 rpm respectively for single-pass and double-pass. Microstructure observations of the welded area were studied using an optical microscope. The specimens were tested by using a tensile test and Vickers hardness test to evaluate their mechanical properties. The results indicated that, at low rotational speed, defects such as ‘surface lack of fill’ and tunnels in the welded area contributed to a decrease in mechanical properties. Welded specimens using double-pass techniques show increasing values of tensile strength and hardness. From this investigation it is found that the best parameters of FSW welded aluminium AA1100 plate were those using double-pass techniques that produce mechanically sound joints with a hardness of 56.38 HV and 108 MPa strength at 1800 rpm compared to the single-pass technique. Friction stir welding, single-pass/ double-pass techniques, AA1100, microstructure, mechanical properties.

  14. In-syringe-stirring: A novel approach for magnetic stirring-assisted dispersive liquid–liquid microextraction

    International Nuclear Information System (INIS)

    Horstkotte, Burkhard; Suárez, Ruth; Solich, Petr; Cerdà, Víctor

    2013-01-01

    Graphical abstract: -- Highlights: •We propose a new automatic magnetic stirring assisted dispersive liquid–liquid microextraction. •It allows the extraction of aluminum from seawater and freshwater samples within less than 4 min. •The method was applicable to the natural samples. -- Abstract: For the first time, the use of a magnetic stirrer within the syringe of an automated syringe pump and the resulting possible analytical applications are described. A simple instrumentation following roughly the one from sequential injection analyzer systems is used in combination with an adaptor, which is placed onto the barrel of a glass syringe. Swirling around the longitudinal axis of the syringe and holding two strong neodymium magnets, it causes a rotating magnetic field and serves as driver for a magnetic stirring bar placed inside of the syringe. In a first study it was shown that this approach leads to a sealed but also automatically adaptable reaction vessel, the syringe, in which rapid and homogeneous mixing of sample with the required reagents within short time can be carried out. In a second study in-a-syringe magnetic stirring-assisted dispersive liquid–liquid microextraction (MSA-DLLME) was demonstrated by the application of the analyzer system to fluorimetric determination of aluminum in seawater samples using lumogallion. A linear working range up to 1.1 μmol L −1 and a limit of detection of 6.1 nmol L −1 were found. An average recovery of 106.0% was achieved for coastal seawaters with a reproducibility of 4.4%. The procedure lasted 210 s including syringe cleaning and only 150 μL of hexanol and 4.1 mL of sample were required

  15. Apparatus for real-time size and speed measurements of blow-off particles from pulsed irradiation experiments

    International Nuclear Information System (INIS)

    Von Benken, C.; Johnson, E.A.; Nordberg, M.

    1989-01-01

    The authors present an apparatus capable of detecting micron sized particles traveling at speeds up to 10 6 cm/sec. The apparatus uses light scattering methods with automated data processing. Data generated by this apparatus should be extremely useful in radiation damage studies of components in contamination sensitive optical systems

  16. Modelling of peak temperature during friction stir processing of magnesium alloy AZ91

    Science.gov (United States)

    Vaira Vignesh, R.; Padmanaban, R.

    2018-02-01

    Friction stir processing (FSP) is a solid state processing technique with potential to modify the properties of the material through microstructural modification. The study of heat transfer in FSP aids in the identification of defects like flash, inadequate heat input, poor material flow and mixing etc. In this paper, transient temperature distribution during FSP of magnesium alloy AZ91 was simulated using finite element modelling. The numerical model results were validated using the experimental results from the published literature. The model was used to predict the peak temperature obtained during FSP for various process parameter combinations. The simulated peak temperature results were used to develop a statistical model. The effect of process parameters namely tool rotation speed, tool traverse speed and shoulder diameter of the tool on the peak temperature was investigated using the developed statistical model. It was found that peak temperature was directly proportional to tool rotation speed and shoulder diameter and inversely proportional to tool traverse speed.

  17. Associations between physical performance and executive function in older adults with mild cognitive impairment: gait speed and the timed "up & go" test.

    Science.gov (United States)

    McGough, Ellen L; Kelly, Valerie E; Logsdon, Rebecca G; McCurry, Susan M; Cochrane, Barbara B; Engel, Joyce M; Teri, Linda

    2011-08-01

    Older adults with amnestic mild cognitive impairment (aMCI) are at higher risk for developing Alzheimer disease. Physical performance decline on gait and mobility tasks in conjunction with executive dysfunction has implications for accelerated functional decline, disability, and institutionalization in sedentary older adults with aMCI. The purpose of this study was to examine whether performance on 2 tests commonly used by physical therapists (usual gait speed and Timed "Up & Go" Test [TUG]) are associated with performance on 2 neuropsychological tests of executive function (Trail Making Test, part B [TMT-B], and Stroop-Interference, calculated from the Stroop Word Color Test) in sedentary older adults with aMCI. The study was a cross-sectional analysis of 201 sedentary older adults with memory impairment participating in a longitudinal intervention study of cognitive function, aging, exercise, and health promotion. Physical performance speed on gait and mobility tasks was measured via usual gait speed and the TUG (at fast pace). Executive function was measured with the TMT-B and Stroop-Interference measures. Applying multiple linear regression, usual gait speed was associated with executive function on both the TMT-B (β=-0.215, P=.003) and Stroop-Interference (β=-0.195, P=.01) measures, indicating that slower usual gait speed was associated with lower executive function performance. Timed "Up & Go" Test scores (in logarithmic transformation) also were associated with executive function on both the TMT-B (β=0.256, Pfunction performance. All associations remained statistically significant after adjusting for age, sex, depressive symptoms, medical comorbidity, and body mass index. The cross-sectional nature of this study does not allow for inferences of causation. Physical performance speed was associated with executive function after adjusting for age, sex, and age-related factors in sedentary older adults with aMCI. Further research is needed to determine

  18. Domestic solid waste and sewage improvement by anaerobic digestion: A stirred digester

    Energy Technology Data Exchange (ETDEWEB)

    Lebrato, J.; Perez-Rodriguez, J.L. [CSIC-UNSE, Instituto de Ciencia de Materiales, Sevilla (Spain); Maqueda, C. [CSIC Instituto de Recursos Naturales y Agrobiologia, Sevilla (Spain)

    1995-05-01

    The processing of the mixture of domestic solid waste and domestic sewage in an stirring digester was studied. The experimental set up consisted of six thermostatically controlled digesters of 1 l, each one in a bath at 35{+-}1oC and magnetically stirred. The best feeding for the culture was 1.7 g COD l{sup -1} day{sup -1}. The minimum hydraulic retention time was 6 days. The efficiency in COD removal of treatment varied between 90.1% and 72.4%. The biogas productivity was 0.19 l g{sup -1} COD day{sup -1}

  19. MR STIR imaging versus spin-echo imaging of the breast

    International Nuclear Information System (INIS)

    Zobel, B.B.; Tella, S.; Patrizio, G.; Confalone, D.; D'Archivio, C.; Passariello, R.

    1989-01-01

    A valid tissue characterization of human breast diseases with conventional spin-echo (SE) sequences has not been achieved yet. In spite of experimental works showing that fibroadenomas have a small but significant difference in T1 relaxation time, T1- and T2-weighted SE sequences are not always able to differentiate them. We tried to solve the problem employing two different short T1 inversion-recovery (STIR) sequences with T1 values adequate to nullify the signal of glandular and fatty tissues. This paper reports on twenty-five nodules, including cysts, fibroadenomas, phylloids, and adenocarcinomas, examined with both STIR sequences performed on a superconductive 0.5-T unit

  20. Compared production behavior of borax and unborax premixed SiC reinforcement Al7Si-Mg-TiB alloys composites with semi-solid stir casting method

    Science.gov (United States)

    Haryono, M. B.; Sulardjaka, Nugroho, Sri

    2016-04-01

    The present study was aimed to investigate the effect of borax additive on physical and mechanical properties of Al7Si-Mg-TiB with the reinforcement of silicon carbide. In this case, the different weight percentage from the reinforcement of SiC (10, 15, and 20% wt), and the borax additive (ratio 1:4) were homogenously added into the matrix by employing the semi-solid stir casting method at the temperature of 590°C. Al7Si-Mg-TiB melted in an electric resistance furnace at 800°C for 25 minutes and the holding time of 5 minutes; SiC was stirred with borax inside the chamber and heated at the temperature of 250°C for 25 minutes. Then, it melted by lowing the temperature into 590°C. The SiC-borax mixture was added into the electric resistance furnace, and automatically stirred by the stirrer at a constant speed (500 rpm for 3 minutes) in the composite A17Si-Mg-TiB. It melted when heated at 750°C for 17minutes,then, casting was performed on the prepared mould. The characterizations of Al7Si-Mg-TiB-SiC/borax were porosity, hardness, and microstructure on the Al7Si-Mg-TiB-SiC/ borax. The porosity of AMC tended to increase along with the increaseof the wt% SiC (1.4%-3.6%); however, borax additive underwent a decrease in porosity (0.14%-1.3%). Further, hardness tended to improve along with the increase of wt% SiC. The unboraxmixture had 79,6 HRB up to 94 HRB. Whereas, the borax additive mixture had 105,8 HRB up to 121 HRB.

  1. Rapid Genome Detection of Schmallenberg Virus and Bovine Viral Diarrhea Virus by Use of Isothermal Amplification Methods and High-Speed Real-Time Reverse Transcriptase PCR

    OpenAIRE

    Aebischer, Andrea; Wernike, Kerstin; Hoffmann, Bernd; Beer, Martin

    2014-01-01

    Over the past few years, there has been an increasing demand for rapid and simple diagnostic tools that can be applied outside centralized laboratories by using transportable devices. In veterinary medicine, such mobile test systems would circumvent barriers associated with the transportation of samples and significantly reduce the time to diagnose important infectious animal diseases. Among a wide range of available technologies, high-speed real-time reverse transcriptase quantitative PCR (R...

  2. Microstructure and anisotropic mechanical behavior of friction stir welded AA2024 alloy sheets

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhihan [State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China); Li, Wenya, E-mail: liwy@nwpu.edu.cn [State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China); Li, Jinglong [State Key Laboratory of Solidification Processing, Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi' an 710072, Shaanxi (China); Chao, Y.J. [Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Vairis, A. [Mechanical Engineering Department, TEI of Crete, Heraklion, Crete 71004 (Greece)

    2015-09-15

    The anisotropic mechanical properties of friction stir welded (FSW) AA2024-T3 alloy joints were investigated based on the uniaxial tensile tests. The joint microstructure was examined by using electron back-scattered diffraction and transmission electron microscope. Results show that the evident anisotropic failure and yielding are present in the FSW joints. With the increase of loading angle from 0° to 90° the ultimate tensile strength and elongation of the specimens consistently decrease, or at first decrease and then increase, depending on the FSW process parameters. The specimen cut from the weld direction, i.e. a loading angle of 0°, exhibits the highest strength and elongation. - Highlights: • Microstructure and anisotropy of friction stir welded joints were studied. • The evident anisotropic failure and yielding are present in joints. • The lowest yield stress and UTS are at 45° and 60° loadings, respectively. • Rotation speed heavily impact on the anisotropy of joints.

  3. Surface enhancement of cold work tool steels by friction stir processing with a pinless tool

    Science.gov (United States)

    Costa, M. I.; Verdera, D.; Vieira, M. T.; Rodrigues, D. M.

    2014-03-01

    The microstructure and mechanical properties of enhanced tool steel (AISI D2) surfaces produced using a friction stir welding (FSW) related procedure, called friction stir processing (FSP), are analysed in this work. The surface of the tool steel samples was processed using a WC-Co pinless tool and varying processing conditions. Microstructural analysis revealed that meanwhile the original substrate structure consisted of a heterogeneous distribution of coarse carbides in a ferritic matrix, the transformed surfaces consisted of very small carbides, homogenously distributed in a ferrite- bainite- martensite matrix. The morphology of the surfaces, as well as its mechanical properties, evaluated by hardness and tensile testing, were found to vary with increasing tool rotation speed. Surface hardness was drastically increased, relative to the initial hardness of bulk steel. This was attributed to ferrite and carbide refinement, as well as to martensite formation during solid state processing. At the highest rotation rates, tool sliding during processing deeply compromised the characteristics of the processed surfaces.

  4. Microstructure and wear behavior of friction stir processed cast hypereutectic aluminum silicon

    Directory of Open Access Journals (Sweden)

    Ahmad Rosli

    2017-01-01

    Full Text Available Hypereutectic as-cast Al-18Si-Cu-Ni alloy was subjected to friction stir processing (FSP. The resultant effect of FSP on the alloy was evaluated by microstructure analysis and wear tests (dry sliding. A significant microstructural modification and enhancement in wear behavior of Al-18Si-Cu-Ni alloy was recorded after friction stir processing. Wear resistance improvement was related to considerable modification in size, morphology and distribution of silicon particles, and hardness improvement. It was found that lower tool rotation speed was more effective to refine silicon particles and in turn increase wear resistance. Minimum Si particle mean area of about 47.8 µm2, and wear rate of 0.0155 mg/m was achieved.

  5. Microstructure and anisotropic mechanical behavior of friction stir welded AA2024 alloy sheets

    International Nuclear Information System (INIS)

    Zhang, Zhihan; Li, Wenya; Li, Jinglong; Chao, Y.J.; Vairis, A.

    2015-01-01

    The anisotropic mechanical properties of friction stir welded (FSW) AA2024-T3 alloy joints were investigated based on the uniaxial tensile tests. The joint microstructure was examined by using electron back-scattered diffraction and transmission electron microscope. Results show that the evident anisotropic failure and yielding are present in the FSW joints. With the increase of loading angle from 0° to 90° the ultimate tensile strength and elongation of the specimens consistently decrease, or at first decrease and then increase, depending on the FSW process parameters. The specimen cut from the weld direction, i.e. a loading angle of 0°, exhibits the highest strength and elongation. - Highlights: • Microstructure and anisotropy of friction stir welded joints were studied. • The evident anisotropic failure and yielding are present in joints. • The lowest yield stress and UTS are at 45° and 60° loadings, respectively. • Rotation speed heavily impact on the anisotropy of joints

  6. A study on heat-flow analysis of friction stir welding on a rotation affected zone

    International Nuclear Information System (INIS)

    Kang, Sung Wook; Jang, Beom Seon; Kim, Jae Woong

    2014-01-01

    In recent years, as interest in environmental protection and energy conservation rose, technological development for lightweight efficiency of transport equipment, such as aircrafts, railcars, automobiles and vessels, have been briskly proceeding. This has led to an expansion of the application of lightweight alloys such as aluminum and magnesium. For the welding of these lightweight alloys, friction stir welding has been in development by many researchers. Heat-flow analysis of friction stir welding is one such research. The flow and energy equation is solved using the computational fluid dynamic commercial program 'Fluent'. In this study, a rotation affected zone concept is imposed. The rotation affected zone is a constant volume. In this volume, flow is rotated the same as the tool rotation speed and so plastic dissipation occurs. Through this simulation, the temperature distribution results are calculated and the simulation results are compared with the experimental results.

  7. Friction stir spot welding of 2024-T3 aluminum alloy with SiC nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Paidar, Moslem; Sarab, Mahsa Laali [Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2016-01-15

    In this study, the Friction stir spot welding (FSSW) of 2024-T3 aluminum alloy with 1.6 mm thickness was investigated. The effects of the silicon carbide (SiC) nanoparticles on the metallurgical and mechanical properties were discussed. The effects of particles on tension shear and wear tests were also investigated. The process was conducted at a constant rotational speed of 1000 rpm. Results showed that adding SiC nanoparticles to the weld during FSSW had a major effect on the mechanical properties. In fact, the addition of nanoparticles as barriers prevented grain growth in the Stir zone (SZ). The data obtained in the tensile-shear and wear tests showed that tensile-shear load and wear resistance increased with the addition of SiC nanoparticles, which was attributed to the fine grain size produced in the SZ.

  8. Effect of FSW welding speed on microstructure and microhardness of Al-0.84Mg-0.69Si-0.76Fe alloy at moderate rotational tool velocity

    Science.gov (United States)

    Chand, Suresh; Vineetha, S.; Madhusudhan, D.; Sai Krishna, CH; Kusuma Devi, G.; Bhawani; Hemarao, K.; Ganesh Naidu, G.

    2018-03-01

    The plate of 7.0 mm thickness was double side welded using friction stir welding is investigated. The rotational velocity of friction stir welding tool is used 1400 rpm. The influence of welding speed on the microstructure and microhardness values of Al-0.84Mg-0.69Si-0.76Fe aluminum alloy is presented. Two welding speeds 25 mm/min and 31.5 mm/min are used. The microhardness values of friction stir weld are measured at various locations from the weld interface. The microhardness values in stir zone of weld are found larger than lower welding speed at constant rotational velocity of 1400 rpm of friction stir welding tool. The similar effects on microhardness values are found in the thermo-mechanically affected zone and heat affected zone. The fine microstructure is observed at 31.5 mm/min welding speed compared to the 25 mm/min welding speed at 1400 rpm.

  9. Speed in Acquisitions

    DEFF Research Database (Denmark)

    Meglio, Olimpia; King, David R.; Risberg, Annette

    2017-01-01

    The advantage of speed is often invoked by academics and practitioners as an essential condition during post-acquisition integration, frequently without consideration of the impact earlier decisions have on acquisition speed. In this article, we examine the role speed plays in acquisitions across...... the acquisition process using research organized around characteristics that display complexity with respect to acquisition speed. We incorporate existing research with a process perspective of acquisitions in order to present trade-offs, and consider the influence of both stakeholders and the pre......-deal-completion context on acquisition speed, as well as the organization’s capabilities to facilitating that speed. Observed trade-offs suggest both that acquisition speed often requires longer planning time before an acquisition and that associated decisions require managerial judgement. A framework for improving...

  10. Characterization of boron carbide particulate reinforced in situ copper surface composites synthesized using friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Sathiskumar, R., E-mail: sathiscit2011@gmail.com [Department of Mechanical Engineering, Coimbatore Institute of Technology, Coimbatore, 641 014 Tamil Nadu (India); Murugan, N., E-mail: murugan@cit.edu.in [Department of Mechanical Engineering, Coimbatore Institute of Technology, Coimbatore, 641 014 Tamil Nadu (India); Dinaharan, I., E-mail: dinaweld2009@gmail.com [Department of Mechanical Engineering, V V College of Engineering, Tisaiyanvilai, 627 657 Tamil Nadu (India); Vijay, S.J., E-mail: vijayjoseph@karunya.edu [Centre for Research in Metallurgy (CRM), School of Mechanical Sciences, Karunya University, Coimbatore, 641 114 Tamil Nadu (India)

    2013-10-15

    Friction stir processing has evolved as a novel solid state technique to fabricate surface composites. The objective of this work is to apply the friction stir processing technique to fabricate boron carbide particulate reinforced copper surface composites and investigate the effect of B{sub 4}C particles and its volume fraction on microstructure and sliding wear behavior of the same. A groove was prepared on 6 mm thick copper plates and packed with B{sub 4}C particles. The dimensions of the groove was varied to result in five different volume fractions of B{sub 4}C particles (0, 6, 12, 18 and 24 vol.%). A single pass friction stir processing was done using a tool rotational speed of 1000 rpm, travel speed of 40 mm/min and an axial force of 10 kN. Metallurgical characterization of the Cu/B{sub 4}C surface composites was carried out using optical microscope and scanning electron microscope. The sliding wear behavior was evaluated using a pin-on-disk apparatus. Results indicated that the B{sub 4}C particles significantly influenced the area, dispersion, grain size, microhardness and sliding wear behavior of the Cu/B{sub 4}C surface composites. When the volume fraction of B{sub 4}C was increased, the wear mode changed from microcutting to abrasive wear and wear debris was found to be finer. Highlights: • Fabrication of Cu/B{sub 4}C surface composite by friction stir processing • Analyzing the effect of B{sub 4}C particles on the properties of Cu/B4C surface composite • Increased volume fraction of B{sub 4}C particles reduced the area of surface composite. • Increased volume fraction of B{sub 4}C particles enhanced the microhardness and wear rate. • B{sub 4}C particles altered the wear mode from microcutting to abrasive.

  11. Microstructural characterisation of friction stir welding joints of mild steel to Ni-based alloy 625

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, J. [Brazilian Nanotechnology National Laboratory (LNNano), P.O. Box 6192, Campinas, SP (Brazil); University of Campinas (UNICAMP), Campinas, SP (Brazil); Ramirez, A.J., E-mail: ramirezlondono.1@osu.edu [Brazilian Nanotechnology National Laboratory (LNNano), P.O. Box 6192, Campinas, SP (Brazil); University of Campinas (UNICAMP), Campinas, SP (Brazil); Department of Materials Science and Engineering, The Ohio State University — OSU, Columbus, OH 43221 (United States)

    2015-12-15

    In this study, 6-mm-thick mild steel and Ni-based alloy 625 plates were friction stir welded using a tool rotational speed of 300 rpm and a travel speed of 100 mm·min{sup −1}. A microstructural characterisation of the dissimilar butt joint was performed using optical microscopy, scanning and transmission electron microscopy, and energy dispersive X-ray spectroscopy (XEDS). Six different weld zones were found. In the steel, the heat-affected zone (HAZ) was divided into three zones and was composed of ferrite, pearlite colonies with different morphologies, degenerated regions of pearlite and allotriomorphic and Widmanstätten ferrite. The stir zone (SZ) of the steel showed a coarse microstructure consisting of allotriomorphic and Widmanstätten ferrite, degenerate pearlite and MA constituents. In the Ni-based alloy 625, the thermo-mechanically affected zone (TMAZ) showed deformed grains and redistribution of precipitates. In the SZ, the high deformation and temperature produced a recrystallised microstructure, as well as fracture and redistribution of MC precipitates. The M{sub 23}C{sub 6} precipitates, present in the base material, were also redistributed in the stir zone of the Ni-based alloy. TMAZ in the steel and HAZ in the Ni-based alloy could not be identified. The main restorative mechanisms were discontinuous dynamic recrystallisation in the steel, and discontinuous and continuous dynamic recrystallisation in the Ni-based alloy. The interface region between the steel and the Ni-based alloy showed a fcc microstructure with NbC carbides and an average length of 2.0 μm. - Highlights: • Comprehensive microstructural characterisation of dissimilar joints of mild steel to Ni-based alloy • Friction stir welding of joints of mild steel to Ni-based alloy 625 produces sound welds. • The interface region showed deformed and recrystallised fcc grains with NbC carbides and a length of 2.0 μm.

  12. Microstructural characterization in dissimilar friction stir welding between 304 stainless steel and st37 steel

    International Nuclear Information System (INIS)

    Jafarzadegan, M.; Feng, A.H.; Abdollah-zadeh, A.; Saeid, T.; Shen, J.; Assadi, H.

    2012-01-01

    In the present study, 3 mm-thick plates of 304 stainless steel and st37 steel were welded together by friction stir welding at a welding speed of 50 mm/min and tool rotational speed of 400 and 800 rpm. X-ray diffraction test was carried out to study the phases which might be formed in the welds. Metallographic examinations, and tensile and microhardness tests were used to analyze the microstructure and mechanical properties of the joint. Four different zones were found in the weld area except the base metals. In the stir zone of the 304 stainless steel, a refined grain structure with some features of dynamic recrystallization was evidenced. A thermomechanically-affected zone was characterized on the 304 steel side with features of dynamic recovery. In the other side of the stir zone, the hot deformation of the st37 steel in the austenite region produced small austenite grains and these grains transformed to fine ferrite and pearlite and some products of displacive transformations such as Widmanstatten ferrite and martensite by cooling the material after friction stir welding. The heat-affected zone in the st37 steel side showed partially and fully refined microstructures like fusion welding processes. The recrystallization in the 304 steel and the transformations in the st37 steel enhanced the hardness of the weld area and therefore, improved the tensile properties of the joint. - Highlights: ► FSW produced sound welds between st37 low carbon steel and 304 stainless steel. ► The SZ of the st37 steel contained some products of allotropic transformation. ► The material in the SZ of the 304 steel showed features of dynamic recrystallization. ► The finer microstructure in the SZ increased the hardness and tensile strength.

  13. Tensile behavior of dissimilar friction stir welded joints of aluminium alloys

    International Nuclear Information System (INIS)

    Shanmuga Sundaram, N.; Murugan, N.

    2010-01-01

    The heat treatable aluminium alloy AA2024 is used extensively in the aircraft industry because of its high strength to weight ratio and good ductility. The non-heat treatable aluminium alloy AA5083 possesses medium strength and high ductility and used typically in structural applications, marine, and automotive industries. When compared to fusion welding processes, friction stir welding (FSW) process is an emerging solid state joining process which is best suitable for joining these alloys. The friction stir welding parameters such as tool pin profile, tool rotational speed, welding speed, and tool axial force influence the mechanical properties of the FS welded joints significantly. Dissimilar FS welded joints are fabricated using five different tool pin profiles. Central composite design with four parameters, five levels, and 31 runs is used to conduct the experiments and response surface method (RSM) is employed to develop the model. Mathematical regression models are developed to predict the ultimate tensile strength (UTS) and tensile elongation (TE) of the dissimilar friction stir welded joints of aluminium alloys 2024-T6 and 5083-H321, and they are validated. The effects of the above process parameters and tool pin profile on tensile strength and tensile elongation of dissimilar friction stir welded joints are analysed in detail. Joints fabricated using Tapered Hexagon tool pin profile have the highest tensile strength and tensile elongation, whereas the Straight Cylinder tool pin profile have the lowest tensile strength and tensile elongation. The results are useful to have a better understanding of the effects of process parameters, to fabricate the joints with desired tensile properties, and to automate the FS welding process.

  14. Applications of a saving method with max-min ant system to a vehicle routing problem with time windows and speed limits

    Directory of Open Access Journals (Sweden)

    Suphan Sodsoon

    2014-06-01

    Full Text Available This study aims to solve a Vehicle Routing Problem with Time Windows and Speed Limits (VRPTWSL, which has received considerable attention in recent years. The vehicle routing problem with time windows is an extension of the well-known Vehicle Routing Problem (VRP and involves a fleet of vehicles set of from a depot to serve a number of customers at different geographic locations with various demands within specific time and speed limits before returning to the depot eventually. To solve the problem, an efficient Saving Method-Max Min Ant System (Saving-MMAS with Local Search algorithm is applied. Using minimization of the total transportation costs as the objective of the extension VRPTWSL, a mathematic model is constructed. Finally, the Saving-MMAS algorithms indicated the good quality of the method in this problem.

  15. Nondestructive Evaluation of Friction Stir-Welded Aluminum Alloy to Coated Steel Sheet Lap Joint

    Science.gov (United States)

    Das, H.; Kumar, A.; Rajkumar, K. V.; Saravanan, T.; Jayakumar, T.; Pal, Tapan Kumar

    2015-11-01

    Dissimilar lap joints of aluminum sheet (AA 6061) of 2 mm thickness and zinc-coated steel sheet of 1 mm thickness were produced by friction stir welding with different combinations of rotational speed and travel speed. Ultrasonic C- and B-scanning, and radiography have been used in a complementary manner for detection of volumetric (cavity and flash) and planar (de bond) defects as the defects are in micron level. Advanced ultrasonic C-scanning did not provide any idea about the defects, whereas B-scanning cross-sectional image showed an exclusive overview of the micron-level defects. A digital x-ray radiography methodology is proposed for quality assessment of the dissimilar welds which provide three-fold increase in signal-to-noise ratio with improved defect detection sensitivity. The present study clearly shows that the weld tool rotational speed and travel speed have a decisive role on the quality of the joints obtained by the friction stir welding process. The suitability of the proposed NDE techniques to evaluate the joint integrity of dissimilar FSW joints is thus established.

  16. Study of Dissimilar Welding AA6061 Aluminium Alloy and AZ31B Magnesium Alloy with ER5356 Filler Using Friction Stir Welding

    Science.gov (United States)

    Mahamud, M. I. I.; Ishak, M.; Halil, A. M.

    2017-09-01

    This paper is to study of dissimilar welding AA6061 aluminium alloy and AZ31B magnesium alloy with ER5356 filler using friction stir welding. 2 mm thick plates of aluminium and magnesium were used. Friction stir welding operations were performed at different rotation and travel speeds and used the fixed tilt angle which is 3°. The rotation speeds varied from 800 to 1100 rpm, and the travel speed varied from 80 to 100 mm/min. In the range rotation speed of 800 to 1000 rpm and welding speed of 80 to 100 mm/min there are no defect at the weld. Tensile test show the higher tensile strength is 198 MPa and the welding efficiency is about 76%.

  17. Ozone gradients in a spruce forest stand in relation to wind speed and time of the day

    Science.gov (United States)

    Pleijel, H.; Wallin, G.; Karlsson, P. E.; Skärby, L.

    Ozone concentrations were measured outside and inside a 60-year-old 15-20 m tall spruce forest at a wind-exposed forest edge in southwest Sweden, at 3 and 13 m height 15 m outside the forest, and at 3 and 13 m height inside the forest 45 m from the forest edge. Measurements at 3 m were made with three replicate tubes on each site, the replicates being separated by 10 m. In addition, horizontal and vertical wind speeds were measured at 8 m height outside and inside the forest. During daytime, the concentrations inside the forest were generally slightly lower. Negative ozone concentration gradients from the open field into the forest were observed at 3 m height when the wind speed was below approximately 1.5 m s -1. At very low wind speeds, mainly occurring during the night, the ozone concentrations at 3 m height were frequently higher inside the forest than outside the forest. This may be caused by a very large aerodynamic resistance to ozone deposition, due to very small air movements inside the forest under stable conditions. It is concluded that ozone uptake by the trees is likely to be very small at night, even if stomata are not entirely closed. Results from open-top chamber experiments are also discussed.

  18. Optimization of multi-slice helical respiration-correlated CT: the effects of table speed and rotation time

    International Nuclear Information System (INIS)

    Wink, Nicole M; McNitt-Gray, Michael F; Solberg, Timothy D

    2005-01-01

    While respiration-correlated CT is gaining acceptance in clinical radiotherapy, the effect of scanning parameters on the image quality has yet to be addressed. The intent of this study was to characterize the effects of gantry rotation and table speed on various image quality characteristics in multi-slice, helical, retrospectively-gated CT images. Images of stationary and moving phantoms were obtained in helical mode on a 20-slice CT scanner. Motion was generated by a computer-controlled platform capable of moving simultaneously in two dimensions. Motion was monitored using a pressure gauge inserted inside an adjustable belt. Selected scans were retrospectively gated into ten phases based on the monitored motion. Gantry rotation speeds of 0.5 s and 1.0 s were evaluated with pitches ranging from 0.1 to 0.45. Several parameters, including calculated object volumes, trajectory (movement from peak to trough), deformation (actual volume divided by volume created with the maximum diameter of contoured object) and z-axis resolution, were used to characterize image quality. These studies indicate that for objects in the peak phase of a movement pattern that simulates breathing, retrospectively gated scans using fast gantry rotation speeds produce volume, trajectory, deformation and z-axis resolution results comparable with those of a stationary object

  19. Thermal modelling of friction stir welding

    DEFF Research Database (Denmark)

    Schmidt, Henrik Nikolaj Blicher; Hattel, Jesper Henri

    2008-01-01

    The objective of the present work is to present the basic elements of the thermal modelling of friction stir welding as well as to clarify some of the uncertainties in the literature regarding the different contributions to the heat generation. Some results from a new thermal pseudomechanical model...... in which the temperature-dependent yield stress of the weld material controls the heat generation are also presented....

  20. Ultrasonic stir welding process and apparatus

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2009-01-01

    An ultrasonic stir welding device provides a method and apparatus for elevating the temperature of a work piece utilizing at least one ultrasonic heater. Instead of relying on a rotating shoulder to provide heat to a workpiece an ultrasonic heater is utilized to provide ultrasonic energy to the workpiece. A rotating pin driven by a motor assembly performs the weld on the workpiece. A handheld version can be constructed as well as a fixedly mounted embodiment.

  1. Experimental data and numerical predictions of a single-phase flow in a batch square stirred tank reactor with a rotating cylinder agitator

    Science.gov (United States)

    Escamilla-Ruíz, I. A.; Sierra-Espinosa, F. Z.; García, J. C.; Valera-Medina, A.; Carrillo, F.

    2017-09-01

    Single-phase flows in stirred tank reactors have useful characteristics for a wide number of industrial applications. Usually, reactors are cylindrical vessels and complex impeller designs, which are often highly energy consuming and produce complicated flow patterns. Therefore, a novel configuration consisting of a square stirred tank reactor is proposed in this study with potential advantages over conventional reactors. In the present work hydrodynamics and turbulence have been studied for a single-phase flow in steady state operating in batch condition. The flow was induced by drag from a rotating cylinder with two diameters. The effects of drag from the stirrer as well as geometrical parameters of the system on the hydrodynamic behavior were investigated using Computational Fluids Dynamics (CFD) and non-intrusive Laser Doppler Anemometry, (LDA). Data obtained from LDA measurements were used for the validation of the CFD simulations, and to detecting the macro-instabilities inside the tank, based on the time series analysis for three rotational speeds N = 180, 1000 and 2000 rpm. The numerical results revealed the formation of flow patterns and macro-vortex structures in the upper part of the tank as consequence of the Reynolds number and the stream discharge emanated from the cylindrical stirrer. Moreover, increasing the cylinder diameter has an impact on the number of recirculation loops as well as the energy consumption of the entire system showing better performance in the presence of turbulent flows.

  2. Identifying Combination of Friction Stir Welding Parameters to Maximize Strength of Lap Joints of AA2014-T6 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Rajendrana C.

    2017-01-01

    Full Text Available AA2014 aluminum alloy (Al-Cu alloy has been widely utilized in fabrication of lightweight structures like aircraft structures, demanding high strength to weight ratio and good corrosion resistance. The fusion welding of these alloys will lead to solidification problems such as hot cracking. Friction stir welding is a new solid state welding process, in which the material being welded does not melt and recast. Lot of research works have been carried out by many researchers to optimize process parameters and establish empirical relationships to predict tensile strength of friction stir welded butt joints of aluminum alloys. However, very few investigations have been carried out on friction stir welded lap joints of aluminum alloys. Hence, in this investigation, an attempt has been made to optimize friction stir lap welding (FSLW parameters to attain maximum tensile strength using statistical tools such as design of experiment (DoE, analysis of variance (ANOVA, response graph and contour plots. By this method, it is found that maximum tensile shear fracture load of 12.76 kN can be achieved if a joint is made using tool rotational speed of 900 rpm, welding speed of 110 mm/min, tool shoulder diameter of 12 mm and tool tilt angle of 1.5°.

  3. Vehicle speed prediction via a sliding-window time series analysis and an evolutionary least learning machine: A case study on San Francisco urban roads

    Directory of Open Access Journals (Sweden)

    Ladan Mozaffari

    2015-06-01

    Full Text Available The main goal of the current study is to take advantage of advanced numerical and intelligent tools to predict the speed of a vehicle using time series. It is clear that the uncertainty caused by temporal behavior of the driver as well as various external disturbances on the road will affect the vehicle speed, and thus, the vehicle power demands. The prediction of upcoming power demands can be employed by the vehicle powertrain control systems to improve significantly the fuel economy and emission performance. Therefore, it is important to systems design engineers and automotive industrialists to develop efficient numerical tools to overcome the risk of unpredictability associated with the vehicle speed profile on roads. In this study, the authors propose an intelligent tool called evolutionary least learning machine (E-LLM to forecast the vehicle speed sequence. To have a practical evaluation regarding the efficacy of E-LLM, the authors use the driving data collected on the San Francisco urban roads by a private Honda Insight vehicle. The concept of sliding window time series (SWTS analysis is used to prepare the database for the speed forecasting process. To evaluate the performance of the proposed technique, a number of well-known approaches, such as auto regressive (AR method, back-propagation neural network (BPNN, evolutionary extreme learning machine (E-ELM, extreme learning machine (ELM, and radial basis function neural network (RBFNN, are considered. The performances of the rival methods are then compared in terms of the mean square error (MSE, root mean square error (RMSE, mean absolute percentage error (MAPE, median absolute percentage error (MDAPE, and absolute fraction of variances (R2 metrics. Through an exhaustive comparative study, the authors observed that E-LLM is a powerful tool for predicting the vehicle speed profiles. The outcomes of the current study can be of use for the engineers of automotive industry who have been

  4. Process Model for Friction Stir Welding

    Science.gov (United States)

    Adams, Glynn

    1996-01-01

    Friction stir welding (FSW) is a relatively new process being applied for joining of metal alloys. The process was initially developed by The Welding Institute (TWI) in Cambridge, UK. The FSW process is being investigated at NASA/MSEC as a repair/initial weld procedure for fabrication of the super-light-weight aluminum-lithium shuttle external tank. The FSW investigations at MSFC were conducted on a horizontal mill to produce butt welds of flat plate material. The weldment plates are butted together and fixed to a backing plate on the mill bed. A pin tool is placed into the tool holder of the mill spindle and rotated at approximately 400 rpm. The pin tool is then plunged into the plates such that the center of the probe lies at, one end of the line of contact, between the plates and the shoulder of the pin tool penetrates the top surface of the weldment. The weld is produced by traversing the tool along the line of contact between the plates. A lead angle allows the leading edge of the shoulder to remain above the top surface of the plate. The work presented here is the first attempt at modeling a complex phenomenon. The mechanical aspects of conducting the weld process are easily defined and the process itself is controlled by relatively few input parameters. However, in the region of the weld, plasticizing and forging of the parent material occurs. These are difficult processes to model. The model presented here addresses only variations in the radial dimension outward from the pin tool axis. Examinations of the grain structure of the weld reveal that a considerable amount of material deformation also occurs in the direction parallel to the pin tool axis of rotation, through the material thickness. In addition, measurements of the axial load on the pin tool demonstrate that the forging affect of the pin tool shoulder is an important process phenomenon. Therefore, the model needs to be expanded to account for the deformations through the material thickness and the

  5. Parametric study of the Incompletely Stirred Reactor modeling

    Energy Technology Data Exchange (ETDEWEB)

    Mobini, K. [Department of Mechanical Engineering, Shahid Rajaee University, Lavizan, Tehran (Iran); Bilger, R.W. [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney (Australia)

    2009-09-15

    The Incompletely Stirred Reactor (ISR) is a generalization of the widely-used Perfectly Stirred Reactor (PSR) model and allows for incomplete mixing within the reactor. Its formulation is based on the Conditional Moment Closure (CMC) method. This model is applicable to nonpremixed combustion with strong recirculation such as in a gas turbine combustor primary zone. The model uses the simplifying assumptions that the conditionally-averaged reactive-scalar concentrations are independent of position in the reactor: this results in ordinary differential equations in mixture fraction space. The simplicity of the model permits the use of very complex chemical mechanisms. The effects of the detailed chemistry can be found while still including the effects of micromixing. A parametric study is performed here on an ISR for combustion of methane at overall stoichiometric conditions to investigate the sensitivity of the model to different parameters. The focus here is on emissions of nitric oxide and carbon monoxide. It is shown that the most important parameters in the ISR model are reactor residence time, the chemical mechanism and the core-averaged Probability Density Function (PDF). Using several different shapes for the core-averaged PDF, it is shown that use of a bimodal PDF with a low minimum at stoichiometric mixture fraction and a large variance leads to lower nitric oxide formation. The 'rich-plus-lean' mixing or staged combustion strategy for combustion is thus supported. (author)

  6. Peak Stir Zone Temperature During Friction Stir Processing

    Science.gov (United States)

    2010-03-01

    jii reprecipitation. The nonequilibrium trans- formation products of b may include fine Widmanstät- ten a as well as bainite and martensite, depending... bainite , reflecting cooling at 2 to 3 9 101 C/s (Table II), i.e., rates ~104 times that of the as-cast condition. In region 2, the microstructure...Shepard, and O.D. Sherby: J. Iron Steel Inst., 1964, vol. 202, pp. 804–07. 26. O.D. Sherby, B. Walser, C.M. Young, and E.M. Cady: Scripta Metall

  7. An Analysis of Microstructure and Mechanical Properties on Friction Stir Welded Joint of Dissimilar 304 Stainless Steel and Commercially Pure Aluminium

    Directory of Open Access Journals (Sweden)

    Balamagendiravarman M.

    2017-09-01

    Full Text Available In this study, friction stir welding of dissimilar 304 stainless steel and commercially pure aluminium was performed under the following condition of tool rotational speed 1000 rpm, traverse speed 60 mm/min and tool tilt angle 2 degree. Microstructural characterisation was carried out by optical microscope, scanning electron microscope (SEM. Optical images shows that the microstructural change is very minimum in steel side when compared to aluminium side due to the difference in mechanical and thermal properties. The intermetallic compound Al3Fe was observed at the interfacial region and stir region of the welded joint. The maximum ultimate tensile strength is 78% of commercially pure aluminium base metal. Microhardness profile was measured across the weld interface and the maximum value reaches at the stir zone due to the formation of intermettalics.

  8. Pressure management of water distribution systems via the remote real-time control of variable speed pumps

    CSIR Research Space (South Africa)

    Page, Philip R

    2017-08-01

    Full Text Available describes controllers which set the pump speed α, a physical property of the pump. The “proportional control” method (denoted PC), in analogy to the method for PCVs [2, 3, 12, 13], adjusts αi+1 = αi − kpi (Hi −Hsp) (3) where kpi is a dimension-full parameter... constant) Kpi in Eq. 6. An analogous procedure was followed for a PCV [13]. The proposed controller is called the “parameter-dependent P-controller with known constant pump flow” (DCF). The LCF and DCF controllers require Q to be known, either through a...

  9. Influence of agitation speeds and aeration rates on the Xylanase activity of Aspergillus niger SS7

    Directory of Open Access Journals (Sweden)

    Yasser Bakri

    2011-08-01

    Full Text Available In this study, the effect of agitation and aeration rates on xylanase activity of Aspergillus niger SS7 in 3-litre stirred tank bioreactor was investigated. The agitation rates tested were 100, 200 and 300 rpm at each airflow rates of 0.5, 1.0 and 1.5 vvm. The maximum xylanase activity in mono- agitator system was at the agitation speed of 200 rpm and aeration rate of 1.0 vvm. In bi-agitator system, at low agitation speed (100 rpm, the xylanase activity was enhanced by 13% compared to mono- agitator system for an aeration rate of 1.0 vvm. Xylanase productivity in continuous culture was higher by approximately 3.5 times than in batch culture.

  10. Electrodeposition of uranium in stirred liquid cadmium cathode

    International Nuclear Information System (INIS)

    Koyama, T.; Tanaka, H.

    1997-01-01

    The electrodeposition of U in a liquid Cd cathode was known to be hampered by the formation of dendritic U on the Cd surface. Electrotransports of uranium to the stirred liquid Cd cathode were carried out at 773 K for different cathode current densities and different Reynolds number of stirring. The maximum amount of U taken in the liquid Cd cathode without forming dendrites was found to increase with an increasing Reynolds number of stirring and decrease with increasing cathode current density. (orig.)

  11. Effect of Friction Stir Welding Parameters on the Microstructure and Mechanical Properties of AA2024-T4 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    A. W. El-Morsy

    2018-02-01

    Full Text Available In this work, the effects of rotational and traverse speeds on the 1.5 mm butt joint performance of friction stir welded 2024-T4 aluminum alloy sheets have been investigated. Five rotational speeds ranging from 560 to 1800 rpm and five traverse speeds ranging from 11 to 45 mm/min have been employed. The characterization of microstructure and the mechanical properties (tensile, microhardness, and bending of the welded sheets have been studied. The results reveal that by varying the welding parameters, almost sound joints and high performance welded joints can be successfully produced at the rotational speeds of 900 rpm and 700 rpm and the traverse speed of 35 mm/min. The maximum welding performance of joints is found to be 86.3% with 900 rpm rotational speed and 35 mm/min traverse speed. The microhardness values along the cross-section of the joints show a dramatic drop in the stir zone where the lowest value reached is about 63% of the base metal due to the softening of the welded zone caused by the heat input during joining.

  12. High-Speed Photonic Reservoir Computing Using a Time-Delay-Based Architecture: Million Words per Second Classification

    Directory of Open Access Journals (Sweden)

    Laurent Larger

    2017-02-01

    Full Text Available Reservoir computing, originally referred to as an echo state network or a liquid state machine, is a brain-inspired paradigm for processing temporal information. It involves learning a “read-out” interpretation for nonlinear transients developed by high-dimensional dynamics when the latter is excited by the information signal to be processed. This novel computational paradigm is derived from recurrent neural network and machine learning techniques. It has recently been implemented in photonic hardware for a dynamical system, which opens the path to ultrafast brain-inspired computing. We report on a novel implementation involving an electro-optic phase-delay dynamics designed with off-the-shelf optoelectronic telecom devices, thus providing the targeted wide bandwidth. Computational efficiency is demonstrated experimentally with speech-recognition tasks. State-of-the-art speed performances reach one million words per second, with very low word error rate. Additionally, to record speed processing, our investigations have revealed computing-efficiency improvements through yet-unexplored temporal-information-processing techniques, such as simultaneous multisample injection and pitched sampling at the read-out compared to information “write-in”.

  13. Engineered Alloy Structures by Friction Stir Reaction Processing, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I effort examines the feasibility of an innovative surface modification technology incorporating friction stir reaction processing for producing...

  14. Friction Stir Processing of Cast Superalloys, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR effort examines the feasibility of an innovative fabrication technology incorporating sand casting and friction stir processing (FSP) for producing...

  15. Speed and income

    DEFF Research Database (Denmark)

    Fosgerau, Mogens

    2005-01-01

    The relationship between speed and income is established in a microeconomic model focusing on the trade-off between travel time and the risk of receiving a penalty for exceeding the speed limit. This is used to determine when a rational driver will choose to exceed the speed limit. The relationship...... between speed and income is found again in the empirical analysis of a cross-sectional dataset comprising 60,000 observations of car trips. This is used to perform regressions of speed on income, distance travelled, and a number of controls. The results are clearly statistically significant and indicate...... an average income elasticity of speed of 0.02; it is smaller at short distances and about twice as large at the longest distance investigated of 200 km....

  16. Microstructure and Mechanical Characterization of Friction-Stir-Welded Dual-Phase Brass

    Science.gov (United States)

    Ramesh, R.; Dinaharan, I.; Akinlabi, E. T.; Murugan, N.

    2018-03-01

    Friction stir welding (FSW) is an ideal process to join brass to avoid the evaporation of zinc. In the present investigation, 6-mm-thick dual-phase brass plates were joined efficiently using FSW at various tool rotational speeds. The microstructures were studied using optical microscopy, electron backscattered diffraction and transmission electron microscopy. The optical micrographs revealed the evolution of various zones across the joint line. The microstructure of the heat-affected zone was similar to that of base metal. The weld zone exhibited finer grains due to dynamic recrystallization. The recrystallization was inhomogeneous and the inhomogeneity reduced with increased tool rotational speed. The dual phase was preserved in the weld zone due to the retention of zinc. The severe plastic deformation created a lot of dislocations in the weld zone. The weld zone was strengthened after welding. The role of tool rotational speed on the joint strength is further reported.

  17. Influence of friction stir welding process and tool parameters on strength properties of AA7075-T6 aluminium alloy joints

    International Nuclear Information System (INIS)

    Rajakumar, S.; Muralidharan, C.; Balasubramanian, V.

    2011-01-01

    The aircraft aluminium alloys generally present low weldability by traditional fusion welding process. The development of the friction stir welding has provided an alternative improved way of satisfactorily producing aluminium joints, in a faster and reliable manner. In this present work, the influence of process and tool parameters on tensile strength properties of AA7075-T 6 joints produced by friction stir welding was analysed. Square butt joints were fabricated by varying process parameters and tool parameters. Strength properties of the joints were evaluated and correlated with the microstructure, microhardness of weld nugget. From this investigation it is found that the joint fabricated at a tool rotational speed of 1400 rpm, welding speed of 60 mm/min, axial force of 8 kN, using the tool with 15 mm shoulder diameter, 5 mm pin diameter, 45 HRc tool hardness yielded higher strength properties compared to other joints.

  18. Mixing-Structure Relationship in Jet-Stirred Reactors

    KAUST Repository

    Ayass, Wassim W.

    2016-05-26

    In this study, measurements were performed to assess the overall mixing in jet-stirred reactors (JSRs) passively agitated by feed nozzles. The reactor diameter, nozzle shape, and nozzle diameter were varied to determine the effects of these geometrical parameters on mixing. The mixing was studied at ambient conditions using laser absorption spectroscopy to follow the exit concentration of a tracer gas, carbon dioxide, after a step change in its input flow. The results indicate that the use of a JSR of diameter D = 40 mm, having inclined or crossed nozzles of diameter d = 1 mm is recommended for low residence times up to 0.4 sec, while at moderate/high residence times 0.5-5 sec the use of a JSR of D = 56 mm and d = 0.3 mm having crossed nozzles is suggested.

  19. Characteristic evaluation of process parameters of friction stir welding of aluminium 2024 hybrid composites

    Science.gov (United States)

    Sadashiva, M.; Shivanand, H. K.; Vidyasagar, H. N.

    2018-04-01

    The Current work is aimed to investigate the effect of process parameters in friction stir welding of Aluminium 2024 base alloy and Aluminium 2024 matrix alloy reinforced with E Glass and Silicon Carbide reinforcements. The process involved a set of synthesis techniques incorporating stir casting methodology resulting in fabrication of the composite material. This composite material that is synthesized is then machined to obtain a plate of dimensions 100 mm * 50 mm * 6 mm. The plate is then friction stir welded at different set of parameters viz. the spindle speed of 600 rpm, 900 rpm and 1200 rpm and feed rate of 40 mm/min, 80 mm/min and 120 mm/min for analyzing the process capability. The study of the given set of parameters is predominantly important to understand the physics of the process that may lead to better properties of the joint, which is very much important in perspective to its use in advanced engineering applications, especially in aerospace domain that uses Aluminium 2024 alloy for wing and fuselage structures under tension.

  20. Oxygen mass transfer in a stirred tank bioreactor using different impeller configurations for environmental purposes

    Science.gov (United States)

    2013-01-01

    In this study, a miniature stirred tank bioreactor was designed for treatment of waste gas containing benzene, toluene and xylene. Oxygen mass transfer characteristics for various twin and single-impeller systems were investigated for 6 configurations in a vessel with 10 cm of inner diameter and working volume of 1.77L. Three types of impellers, namely, Rushton turbine, Pitched 4blades and Pitched 2blades impellers with downward pumping have been used. Deionized water was used as a liquid phase. With respect to other independent variables such as agitation speed, aeration rate, type of sparger, number of impellers, the relative performance of these impellers was assessed by comparing the values of (KLa) as a key parameter. Based on the experimental data, empirical correlations as a function of the operational conditions have been proposed, to study the oxygen transfer rates from air bubbles generated in the bioreactor. It was shown that twin Rushton turbine configuration demonstrates superior performance (23% to 77% enhancement in KLa) compared with other impeller compositions and that sparger type has negligible effect on oxygen mass transfer rate. Agitation speeds of 400 to 800 rpm were the most efficient speeds for oxygen mass transfer in the stirred bioreactor. PMID:23369581

  1. Friction Stir Welding of Al-B4C Composite Fabricated by Accumulative Roll Bonding: Evaluation of Microstructure and Mechanical Behavior

    Science.gov (United States)

    Moradi Faradonbeh, Alireza; Shamanian, Morteza; Edris, Hossein; Paidar, Moslem; Bozkurt, Yahya

    2018-02-01

    In this investigation, friction stir welding (FSW) of Al-B4C composite fabricated by 10 cycles accumulative roll bonding was conducted. In order to investigate the influences of pin geometry on microstructure and mechanical properties, four different pin geometries (cylindrical, square, triangular and hexagonal) were selected. It was found that FSW parameters had a major effect on the fragmentation and distribution of reinforcement particles in stir zone. When the tool travel speed was increased, the distribution of B4C particles was become gradually uniform in the aluminum matrix. The effect of tool rotational speed on the peak temperature was determined to be greater than the tool travel speed. The attained data of tensile properties and microhardness tests showed that the tool travel speed had bilateral effect on the tensile strength. The maximum tensile joint efficiency was obtained as 238% for FSWed of Al-2%B4C composite to annealed base Al sheet.

  2. Influence of Processing Parameters on the Flow Path in Friction Stir Welding

    Science.gov (United States)

    Schneider, J. A.; Nunes, A. C., Jr.

    2006-01-01

    Friction stir welding (FSW) is a solid phase welding process that unites thermal and mechanical aspects to produce a high quality joint. The process variables are rpm, translational weld speed, and downward plunge force. The strain-temperature history of a metal element at each point on the cross-section of the weld is determined by the individual flow path taken by the particular filament of metal flowing around the tool as influenced by the process variables. The resulting properties of the weld are determined by the strain-temperature history. Thus to control FSW properties, improved understanding of the processing parameters on the metal flow path is necessary.

  3. Friction stir welding of single crystal aluminium

    DEFF Research Database (Denmark)

    Fonda, Richard Warren; Wert, John A.; Reynolds, A.P.

    2007-01-01

    Friction stir welds were prepared in different orientations in an aluminium single crystal. The welds were quenched to preserve the microstructure surrounding the tool and then electron backscattered diffraction was used to reveal the generation of grain boundaries and the evolution...... of crystallographic texture around the tool in each weld. The extent of both dynamic recrystallisation and conventional recrystallisation varied considerably as a function of weld orientation. As the base plate begins to interact with the deformation field surrounding the tool, regions of the single crystal rotate...

  4. Tool for Two Types of Friction Stir Welding

    Science.gov (United States)

    Carter, Robert

    2006-01-01

    A tool that would be useable in both conventional and self-reacting friction stir welding (FSW) has been proposed. The tool would embody both a prior tooling concept for self-reacting FSW and an auto-adjustable pin-tool (APT) capability developed previously as an augmentation for conventional FSW. Some definitions of terms are prerequisite to a meaningful description of the proposed tool. In conventional FSW, depicted in Figure 1, one uses a tool that includes (1) a rotating shoulder on top (or front) of the workpiece and (2) a rotating pin that protrudes from the shoulder into the depth of the workpiece. The main axial force exerted by the tool on the workpiece is reacted through a ridged backing anvil under (behind) the workpiece. When conventional FSW is augmented with an APT capability, the depth of penetration of the pin into the workpiece is varied in real time by a position- or force-control system that extends or retracts the pin as needed to obtain the desired effect. In self-reacting (also known as self-reacted) friction stir welding (SR-FSW), there are two rotating shoulders: one on top (or front) and one on the bottom (or back) of the workpiece. In this case, a threaded shaft protrudes from the tip of the pin to beyond the back surface of the workpiece. The back shoulder is held axially in place against tension by a nut on the threaded shaft. The main axial force exerted on the workpiece by the tool and front shoulder is reacted through the back shoulder and the threaded shaft, back into the FSW machine head, so that a backing anvil is no longer needed. A key transmits torque between the bottom shoulder and the threaded shaft, so that the bottom shoulder rotates with the shaft. A tool for SRFSW embodying this concept was reported in "Mechanism for Self-Reacted Friction Stir Welding" (MFS-31914), NASA Tech Briefs, Vol. 28, No. 10 (October 2004), page 53. In its outward appearance, the proposed tool (see Figure 2) would fit the above description of an SR

  5. Microstructure and microtexture studies of a friction stir welded Al 6061 alloy

    International Nuclear Information System (INIS)

    Kumbhar, N.T.; Tewari, R.; Dey, G.K.; Bhanumurthy, K.; Sahoo, S.K.; Samajdar, I.

    2009-01-01

    Friction stir welding is a solid state joining technique used extensively for the joining of various metals and alloys and also has been applied to the joining of steels. The friction stir welding of Al and its alloys has been extensively delt with over a period exceeding the last decade and a half due to its numerous advantages over other conventional fusion welding techniques in terms of weld quality, efficiency, cost effectiveness etc. to name a few. This technique is being increasingly seeked by industries in mass production/engineering such as the railways, marine and aerospace industries. The friction stir welding of a precipitation hardened Al 6061 alloy plates of 6 mm. thickness was performed at various tool rotation speeds and tool traverse speeds with a constant tilt of 3 deg using a high strength steel (HSS) tool of appropriate dimensions. The cross section of the weld perpendicular to the welding direction was analyzed for a detailed microstructural investigation using electron probe microanalysis, orientation imaging microscopy and transmission electron microscopy. Various microstructural changes are observed in the various regions of the friction stir welded AA 6061. The nugget region which is highly deformed is characterized by the dissolution and reprecipitation of the coarse precipitates, grain size refinement and recrystallization. The adjoining regions near the nugget viz the thermomechanically affected zone (TMAZ) and the heat affected zone (HAZ) also show heterogeneous microstructure in terms of grain size and precipitation which is mainly attributed to the heating cycle experienced during welding. This heterogeneity is also evident from the plot of microhardness distribution across the cross section of the weld region. However, the electron probe microanalysis studies do not show any significant pickup of oxygen in the weld interior as compared to a little oxygen pickup upto 30 μm from the top surface. Further, using orientation imaging

  6. Chiral imprinted polymers as enantiospecific coatings of stir bar sorptive extraction devices.

    Science.gov (United States)

    Gomez-Caballero, Alberto; Guerreiro, Antonio; Karim, Kal; Piletsky, Sergey; Goicolea, M Aranzazu; Barrio, Ramon J

    2011-10-15

    This paper reports the design of Molecularly Imprinted Polymers (MIP) with affinity towards (S)-citalopram using computational modeling for the selection of functional monomers and monomer:template ratio. Acrylamide was selected as functional monomer and the final complex functional monomer/template resulted in a 3:1 ratio. The polymer was synthesized by radical polymerization initiated by UV onto magnetic stir-bars in order to obtain a stir bar sorptive extraction (SBSE) device capable of selective enantiomeric recognition. After successful template removal, the parameters affecting the SBSE procedure (sample volume, ionic strength, extraction time and pH) were optimized for the effective rebinding of the target analyte. The resultant chirally imprinted polymer based stir-bar was able to selectively extract (S)-citalopram from a racemic mixture in an aqueous media with high specificity (specificity factor 4) between 25 and 500 μgL(-1). The MIP coated stir-bars can have significance for enantiospecific sample pre-concentration and subsequent analysis without the need for any chiral chromatographic separation. Copyright © 2011 Elsevier B.V. All rights reserved.

  7.  Running speed during training and percent body fat predict race time in recreational male marathoners

    OpenAIRE

    Barandun U; Knechtle B; Knechtle P; Klipstein A; Rust CA; Rosemann T; Lepers R

    2012-01-01

     Background: Recent studies have shown that personal best marathon time is a strong predictor of race time in male ultramarathoners. We aimed to determine variables predictive of marathon race time in recreational male marathoners by using the same characteristics of anthropometry and training as used for ultramarathoners.Methods: Anthropometric and training characteristics of 126 recreational male marathoners were bivariately and multivariately related to marathon race times.Results...

  8. Friction stir welding (FSW) of AA 6061 T6

    International Nuclear Information System (INIS)

    Cabot, Pedro; Monglioni, Alberto; Carella, Eduardo

    2002-01-01

    The friction-stir process (FSW) developed by England's TWI in the last decade is a new concept in solid phase friction welding that is particularly appropriate for soldering aluminum and its alloys. It offers interesting aspects and can advantageously replace the usual arch processes. It is an automatic process that solders together long pieces by butt or lap welding and, therefore, overcomes the greater limitation of the conventional friction process that can be applied only to pieces with revolution symmetry. FSW is based essentially on the use of a cylindrical tool with a special profile, which is inserted between the surfaces where the materials meet to join them together at a certain rotation speed and under a specific force. The pieces must be rigidly butt bonded or overlapped to prevent movement when the tool moves forward along the joint producing the dispersion of oxides, local plastisizing of the material and the weld. Since its creation FSW has been the subject of many international publications, but until the present work there was no technologically relevant data about tools and procedures. For this reason, when its promising and novel nature was noticed, the CNEA began its own development project in 1997. The main characteristics of the tool are reviewed here and the results of tests carried out to evaluate the influence of the feed velocity on the mechanical properties of the butt joining of a 6.25 mm thick AA6061 T6 plate. Different accumulated aspects of the experience are discussed as well (cw)

  9. The upgrade of KSTAR timing system to support long-pulse operation and high-speed data acquisition

    Energy Technology Data Exchange (ETDEWEB)

    Park, Mikyung, E-mail: mkpark@nfri.re.kr [National Fusion Research Institute (NFRI), Daejeon (Korea, Republic of); Lee, Woongryol; Na, Hoonkyun [National Fusion Research Institute (NFRI), Daejeon (Korea, Republic of)

    2012-12-15

    Since the first campaign of KSTAR in 2008, the home-made timing system had run for the synchronized operation of tokamak. The timing board which featured PMC-form factor, giga-bit optical communication, home-made protocol, multi-triggering capability, using GPS time and being integrated to EPICS (Experimental Physics and Industrial Control System), had advantages of compactness, modularity, platform independency and full functionality for the synchronized tokamak operation. However, there was deficiency in timing accuracy resulting from the engagement of software in realization of timing function and timing jitter due to poor isolation in output ports. Moreover, new requirements were on the rise as the plasma pulse length was getting longer and diagnostics operating at the higher frequency were newly installed. In order to meet new requirements and overcome the problems, the new timing board has been developed. As a result, the performance is remarkably enhanced: timing accuracy less than 5 ns, jitter less than 100 ps, 8 configurable multi-triggering sections, provision of maximum 100 MHz sampling clock. The KSTAR timing system upgraded by introducing the new timing board is participating in the 2011 campaign after calibration and consolidating the established timing system. This paper describes design, development and commissioning results of the new KSTAR timing system.

  10. From perception to action: phase-locked gamma oscillations correlate with reaction times in a speeded response task

    Directory of Open Access Journals (Sweden)

    Körner Ursula

    2007-04-01

    Full Text Available Abstract Background Phase-locked gamma oscillations have so far mainly been described in relation to perceptual processes such as sensation, attention or memory matching. Due to its very short latency (≈90 ms such oscillations are a plausible candidate for very rapid integration of sensory and motor processes. Results We measured EEG in 13 healthy participants in a speeded reaction task. Participants had to press a button as fast as possible whenever a visual stimulus was presented. The stimulus was always identical and did not have to be discriminated from other possible stimuli. In trials in which the participants showed a fast response, a slow negative potential over central electrodes starting approximately 800 ms before the response and highly phase-locked gamma oscillations over central and posterior electrodes between 90 and 140 ms after the stimulus were observed. In trials in which the participants showed a slow response, no slow negative potential was observed and phase-locked gamma oscillations were significantly reduced. Furthermore, for slow response trials the phase-locked gamma oscillations were significantly delayed with respect to fast response trials. Conclusion These results indicate the relevance of phase-locked gamma oscillations for very fast (not necessarily detailed integration processes.

  11. Microstructure and Mechanical Properties of Dissimilar Friction Stir Spot Welding Between St37 Steel and 304 Stainless Steel

    Science.gov (United States)

    Khodadadi, Ali; Shamanian, Morteza; Karimzadeh, Fathallah

    2017-05-01

    In the present study, St37 low-carbon steel and 304 stainless steel were welded successfully, with the thickness of 2 mm, by a friction stir spot welding process carried out at the tool dwell time of 6 s and two different tool rotational speeds of 630 and 1250 rpm. Metallographic examinations revealed four different zones including SZ and HAZ areas of St37 steel and SZ and TMAZ regions of 304 stainless steel in the weld nugget, except the base metals. X-ray diffraction and energy-dispersive x-ray spectroscopy experiments were used to investigate the possible formation of such phases as chromium carbide. Based on these experiments, no chromium carbide precipitation was found. The recrystallization of the weld nugget in the 304 steel and the phase transformations of the weld regions in the St37 steel enhanced the hardness of the weld joint. Hardness changes of joint were acceptable and approximately uniform, as compared to the resistance spot weld. In this research, it was also observed that the tensile/shear strength, as a crucial factor, was increased with the rise in the tool rotational speed. The bond length along the interface between metals, as an effective parameter to increase the tensile/shear strength, was also determined. At higher tool rotational speeds, the bond length was found to be improved, resulting in the tensile/shear strength of 6682 N. Finally, two fracture modes were specified through the fracture mode analysis of samples obtained from the tensile/shear test consisting of the shear fracture mode and the mixed shear/tensile fracture mode.

  12. Friction stir method for forming structures and materials

    Science.gov (United States)

    Feng, Zhili; David, Stan A.; Frederick, David Alan

    2011-11-22

    Processes for forming an enhanced material or structure are disclosed. The structure typically includes a preform that has a first common surface and a recess below the first common surface. A filler is added to the recess and seams are friction stir welded, and materials may be stir mixed.

  13. Damage Tolerance Behavior of Friction Stir Welds in Aluminum Alloys

    Science.gov (United States)

    McGill, Preston; Burkholder, Jonathan

    2012-01-01

    Friction stir welding is a solid state welding process used in the fabrication of various aerospace structures. Self-reacting and conventional friction stir welding are variations of the friction stir weld process employed in the fabrication of cryogenic propellant tanks which are classified as pressurized structure in many spaceflight vehicle architectures. In order to address damage tolerance behavior associated with friction stir welds in these safety critical structures, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data describing fracture behavior, residual strength capability, and cyclic mission life capability of friction stir welds at ambient and cryogenic temperatures have been generated and will be presented in this paper. Fracture behavior will include fracture toughness and tearing (R-curve) response of the friction stir welds. Residual strength behavior will include an evaluation of the effects of lack of penetration on conventional friction stir welds, the effects of internal defects (wormholes) on self-reacting friction stir welds, and an evaluation of the effects of fatigue cycled surface cracks on both conventional and selfreacting welds. Cyclic mission life capability will demonstrate the effects of surface crack defects on service load cycle capability. The fracture data will be used to evaluate nondestructive inspection and proof test requirements for the welds.

  14. Effect of Stirring and Seeding on Whey Protein Fibril Formation

    NARCIS (Netherlands)

    Bolder, S.G.; Sagis, L.M.C.; Venema, P.; Linden, van der E.

    2007-01-01

    The effect of stirring and seeding on the formation of fibrils in whey protein isolate (WPI) solutions was studied. More fibrils of a similar length are formed when WPI is stirred during heating at pH 2 and 80 C compared to samples that were heated at rest. Addition of seeds did not show an

  15. Optimizing the stirring strategy for the vibrating intrinsic reverberation chamber

    NARCIS (Netherlands)

    Serra, Ramiro; Serra, Ramiro; Leferink, Frank Bernardus Johannes

    2010-01-01

    This work describes the definition, application and assessment of a factorial plan with the aim of gaining insight on what kind of stirring strategy could work the best in a vibrating intrinsic reverberation chamber. Three different stirring strategies were defined as factors of a factorial

  16. Steady shear viscosity of stirred yoghurts with varying ropiness

    NARCIS (Netherlands)

    van Marle, M.E.; van Marle, M.E.; van den Ende, Henricus T.M.; de Kruif, C.G.; de Kruif, C.G.; Mellema, J.

    1999-01-01

    Stirred yogurt was viewed as a concentrated dispersion of aggregates consisting of protein particles. The steady-shear behavior of three types of stirred yogurt with varying ropiness was investigated experimentally. To describe the shear-dependent viscosity, a microrheological model was used which

  17. A Rotating Plug Model of Friction Stir Welding Heat Transfer

    Science.gov (United States)

    Raghulapadu J. K.; Peddieson, J.; Buchanan, G. R.; Nunes, A. C.

    2006-01-01

    A simplified rotating plug model is employed to study the heat transfer phenomena associated with the fiction stir welding process. An approximate analytical solution is obtained based on this idealized model and used both to demonstrate the qualitative influence of process parameters on predictions and to estimate temperatures produced in typical fiction stir welding situations.

  18. Certification of a weld produced by friction stir welding

    Science.gov (United States)

    Obaditch, Chris; Grant, Glenn J

    2013-10-01

    Methods, devices, and systems for providing certification of friction stir welds are disclosed. A sensor is used to collect information related to a friction stir weld. Data from the sensor is compared to threshold values provided by an extrinsic standard setting organizations using a certification engine. The certification engine subsequently produces a report on the certification status of the weld.

  19. Increased performance of continuous stirred tank reactor with calcium supplementation

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Zhuliang; Yang, Haijun; Zhi, Xiaohua; Shen, Jianquan [Beijing National Laboratory for Molecular Sciences (BNLMS), New Materials Laboratory, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2010-04-15

    Continuous biohydrogen production with calcium supplementation at low hydraulic retention time (HRT) in a continuous stirred tank reactor (CSTR) was studied to maximize the hydrogen productivity of anaerobic mixed cultures. After stable operations at HRT of 8-4 h, the bioreactor became unstable when the HRT was lowered to 2 h. Supplementation of 100 mg/L calcium at HRT 2 h improved the operation stability through enhancement of cell retention with almost two-fold increase in cell density than that without calcium addition. Hydrogen production rate and hydrogen yield reached 24.5 L/d/L and 3.74 mol H{sub 2}/mol sucrose, respectively, both of which were the highest values our group have ever achieved. The results showed that calcium supplementation can be an effective way to improve the performance of CSTR at low HRT. (author)

  20. Real-time deflection and friction force imaging by bimorph-based resonance-type high-speed scanning force microscopy in the contact mode.

    Science.gov (United States)

    Cai, Wei; Fan, Haiyun; Zhao, Jianyong; Shang, Guangyi

    2014-01-01

    We report herein an alternative high-speed scanning force microscopy method in the contact mode based on a resonance-type piezoelectric bimorph scanner. The experimental setup, the modified optical beam deflection scheme suitable for smaller cantilevers, and a high-speed control program for simultaneous data capture are described in detail. The feature of the method is that the deflection and friction force images of the sample surface can be obtained simultaneously in real time. Images of various samples (e.g., a test grating, a thin gold film, and fluorine-doped tin oxide-coated glass slides) are acquired successfully. The imaging rate is 25 frames per second, and the average scan speed reaches a value of approximately 2.5 cm/s. The method combines the advantages of both observing the dynamic processes of the sample surface and monitoring the frictional properties on the nanometer scale. 07.79.Lh; 07.79.Sp; 68.37.Ps.

  1. The effect of welding parameters on the corrosion behaviour of friction stir welded AA2024-T351

    DEFF Research Database (Denmark)

    Jariyaboon, M; Davenport, A.J.; Ambat, Rajan

    2007-01-01

    The effect of welding parameters (rotation speed and travel speed) on the corrosion behaviour of friction stir welds in the high strength aluminium alloy AA2024-T351 was investigated. It was found that rotation speed plays a major role in controlling the location of corrosion attack. Localised...... intergranular attack was observed in the nugget region for low rotation speed welds, whereas for higher rotation speed welds, attack occurred predominantly in the heat-affected zone. The increase in anodic reactivity in the weld zone was due to the sensitisation of the grain boundaries leading to intergranular...... attack. Enhancement of cathodic reactivity was also found in the nugget as a result of the precipitation of S-phase. The results were compared with samples of AA2024-T351 that had been heat treated to simulate the thermal cycle associated with welding, and with samples that had been exposed to high...

  2. Speed and amplitude of lung tumor motion precisely detected in four-dimensional setup and in real-time tumor-tracking radiotherapy

    International Nuclear Information System (INIS)

    Shirato, Hiroki; Suzuki, Keishiro; Sharp, Gregory C.; Fujita, Katsuhisa R.T.; Onimaru, Rikiya; Fujino, Masaharu; Kato, Norio; Osaka, Yasuhiro; Kinoshita, Rumiko; Taguchi, Hiroshi; Onodera, Shunsuke; Miyasaka, Kazuo

    2006-01-01

    Background: To reduce the uncertainty of registration for lung tumors, we have developed a four-dimensional (4D) setup system using a real-time tumor-tracking radiotherapy system. Methods and Materials: During treatment planning and daily setup in the treatment room, the trajectory of the internal fiducial marker was recorded for 1 to 2 min at the rate of 30 times per second by the real-time tumor-tracking radiotherapy system. To maximize gating efficiency, the patient's position on the treatment couch was adjusted using the 4D setup system with fine on-line remote control of the treatment couch. Results: The trajectory of the marker detected in the 4D setup system was well visualized and used for daily setup. Various degrees of interfractional and intrafractional changes in the absolute amplitude and speed of the internal marker were detected. Readjustments were necessary during each treatment session, prompted by baseline shifting of the tumor position. Conclusion: The 4D setup system was shown to be useful for reducing the uncertainty of tumor motion and for increasing the efficiency of gated irradiation. Considering the interfractional and intrafractional changes in speed and amplitude detected in this study, intercepting radiotherapy is the safe and cost-effective method for 4D radiotherapy using real-time tracking technology

  3. Finite-rate chemistry modelling of non-conventional combustion regimes using a Partially-Stirred Reactor closure: combustion model formulation and implementation details

    OpenAIRE

    Li, Zhiyi; Ferrarotti, Marco; Cuoci, Alberto; Parente, Alessandro

    2018-01-01

    The present work focuses on the numerical simulation ofModerate or Intense Low oxygen Dilution combustion condition, using thePartially-Stirred Reactor model for turbulence-chemistry interactions.The Partially-Stirred Reactor model assumes that reactions are confinedin a specific region of the computational cell, whose mass fractiondepends both on the mixing and the chemical time scales. Therefore, theappropriate choice of mixing and chemical time scales becomes crucial toensure the accuracy ...

  4. Leaching of boron, arsenic and selenium from sedimentary rocks: I. Effects of contact time, mixing speed and liquid-to-solid ratio

    Energy Technology Data Exchange (ETDEWEB)

    Tabelin, Carlito Baltazar, E-mail: carlito@trans-er.eng.hokudai.ac.jp [Laboratory of Soil Environment Engineering, Faculty of Engineering, Hokkaido University, Sapporo (Japan); Hashimoto, Ayaka, E-mail: a.hashimoto@diaconsult.co.jp [DIA Consultants Co. Ltd., Sapporo (Japan); Igarashi, Toshifumi, E-mail: tosifumi@eng.hokudai.ac.jp [Laboratory of Groundwater and Mass Transport, Faculty of Engineering, Hokkaido University, Sapporo (Japan); Yoneda, Tetsuro, E-mail: yonet@eng.hokudai.ac.jp [Laboratory of Soil Environment Engineering, Faculty of Engineering, Hokkaido University, Sapporo (Japan)

    2014-02-01

    Sedimentary rocks of marine origin excavated in tunnel projects were recently identified as potentially hazardous because they could release significant amounts of toxic trace elements when exposed to the environment. This study investigated the leaching characteristics of B, As, Se and the major coexisting ions under various conditions to identify the factors and processes controlling their evolution in the leachate. In addition, we evaluated whether the parameters of the currently used leachability test for excavated rocks were adequate. Although the leachabilities of B, As and Se similarly increased at longer contact times, only those of B and As were influenced by the mixing speed and/or liquid-to-solid ratio (L/S). The majority of trace elements dissolved in the leachate originated from the dissolution of soluble salts formed from seawater of the Cretaceous trapped during the formation of the sedimentary rocks. Moreover, the alkaline pH of the leachates could be attributed to the simultaneous dissolutions at varying degrees of the mineral components of the rocks as well as the precipitation of clay minerals. In the leaching test of excavated rocks for regulatory purposes, the best values of contact time and mixing speed should represent conditions of the highest trace element extractabilities, which in this study were found at longer contact times ( > 48 h) and the fastest mixing speed (200 rpm). The most appropriate L/S for the leaching test is 10 because it was around this L/S that the extractabilities and leaching concentrations of the trace elements were simultaneously observed at their highest values. - Highlights: • B, As and Se leaching increased with time reaching equilibrium after ca. 48 h. • Effect of L/S on B and As leaching was strong but not that much on Se. • All leachates were alkaline regardless of the contact time, mixing speed and L/S. • Na{sup +}–SO{sub 4}{sup 2−} and Na{sup +}–HCO{sub 3}{sup −} type leachates were produced

  5. Versatile Friction Stir Welding/Friction Plug Welding System

    Science.gov (United States)

    Carter, Robert

    2006-01-01

    A proposed system of tooling, machinery, and control equipment would be capable of performing any of several friction stir welding (FSW) and friction plug welding (FPW) operations. These operations would include the following: Basic FSW; FSW with automated manipulation of the length of the pin tool in real time [the so-called auto-adjustable pin-tool (APT) capability]; Self-reacting FSW (SRFSW); SR-FSW with APT capability and/or real-time adjustment of the distance between the front and back shoulders; and Friction plug welding (FPW) [more specifically, friction push plug welding] or friction pull plug welding (FPPW) to close out the keyhole of, or to repair, an FSW or SR-FSW weld. Prior FSW and FPW systems have been capable of performing one or two of these operations, but none has thus far been capable of performing all of them. The proposed system would include a common tool that would have APT capability for both basic FSW and SR-FSW. Such a tool was described in Tool for Two Types of Friction Stir Welding (MFS- 31647-1), NASA Tech Briefs, Vol. 30, No. 10 (October 2006), page 70. Going beyond what was reported in the cited previous article, the common tool could be used in conjunction with a plug welding head to perform FPW or FPPW. Alternatively, the plug welding head could be integrated, along with the common tool, into a FSW head that would be capable of all of the aforementioned FSW and FPW operations. Any FSW or FPW operation could be performed under any combination of position and/or force control.

  6. Dependencies of the speed of adsorption {sup 60}Co(II) from the time on the bentonite from a deposit Jelsovy potok; Zavislosti rychlosti adsorpcie {sup 60}Co(II) od casu na bentonite z lozska Jelsovy potok

    Energy Technology Data Exchange (ETDEWEB)

    Heglasova, K [Univerzita Komenskeho v Bratislave, Prirodovedecka fakulta, Katedra jadrovej chemie, 84215 Bratislava (Slovakia)

    2012-04-25

    Adsorption of cobalt on selected sorbents was studied by radioindicator method in a batch experimental arrangement. Distribution coefficients and adsorption percentage were determined for bentonite - cobalt system as a function of time mixing. For adsorption study there were selected bentonite from the alder creek area. Their main advantages are rapid ion exchange and low permeability. They are also considered as the most promising candidates in multi barrier system in repositories of radioactive waste and spent nuclear fuel. Cobalt solution at two concentrations was stirred from 15 min to 24 h. The experiment results showed that the adsorption is a time dependent process. Rapid adsorption of cobalt in the beginning and later very slow adsorption indicates two adsorption mechanisms, which are ion exchange and adsorption followed by a slow penetration of cobalt into the crystal grid of montmorillonite, the main component of bentonite. The time to reach the adsorption equilibrium was 4 hours. (authors)

  7. Application of modified stir bar with nickel:zinc sulphide nanoparticles loaded on activated carbon as a sorbent for preconcentration of losartan and valsartan and their determination by high performance liquid chromatography.

    Science.gov (United States)

    Pebdani, Arezou Amiri; Dadfarnia, Shayesteh; Shabani, Ali Mohammad Haji; Khodadoust, Saeid; Haghgoo, Soheila

    2016-03-11

    In this study, the stir bar was coated for the first time with the ​nicel:zins sulphide nanoparticles (Ni:ZnS NPs) loaded on activated carbon (AC) (Ni:ZnS-AC) as well as 1-ethyl-3-methylimidazolium hexafluorophosphate ionic liquid (IL) using sol gel technique and was used for stir bar sorptive extraction (SBSE) of losartan (LOS) and valsartan (VAL) as the model compounds. The extracted analytes were then quantified by high performance liquid chromatography (HPLC) equipped with an ultra violet detector. The best extraction performance for LOS and VAL was obtained through the optimization of the parameters affecting SBSE including pH of sample solution, ionic strength, extraction time, volume of desorption solvent, desorption time, and stirring speed. The fractional factorial design (FFD) was used to find the most important parameters, which were then optimized by the central composite design (CCD) and the desirability function (DF). Under the optimal experimental conditions, wide linear ranges of 0.4-50μgL(-1) and 0.5-50μgL(-1) and good RSDs (at level of 5μgL(-1) and n=6) of 4.4 and 4.9% were obtained for LOS and VAL, respectively. With the enrichment factors (EFs) of 188.6 and 184.8-fold, the limits of detection (LODs, S/N=3) of the developed method were found to be 0.12 and 0.15μgL(-1) for LOS and VAL, respectively. The developed method was successfully applied to the determination of LOS and VAL in urine and plasma matrices. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Comparison of a conventional cardiac-triggered dual spin-echo and a fast STIR sequence in detection of spinal cord lesions in multiple sclerosis

    International Nuclear Information System (INIS)

    Bot, J.C.J.; Barkhof, F.; Lycklama a Nijeholt, G.J.; Bergers, E.; Castelijns, J.A.; Polman, C.H.; Ader, H.J.

    2000-01-01

    The current optimal imaging protocol in spinal cord MR imaging in patients with multiple sclerosis includes a long TR conventional spin-echo (CSE) sequence, requiring long acquisition times. Using short tau inversion recovery fast spin-echo (fast STIR) sequences both acquisition time can be shortened and sensitivity in the detection of multiple sclerosis (MS) abnormalities can be increased. This study compares both sequences for the potential to detect both focal and diffuse spinal abnormalities. Spinal cords of 5 volunteers and 20 MS patients were studied at 1.0 T. Magnetic resonance imaging included cardiac-gated sagittal dual-echo CSE and a cardiac-gated fast STIR sequence. Images were scored regarding number, size, and location of focal lesions, diffuse abnormalities and presence/hindrance of artifacts by two experienced radiologists. Examinations were scored as being definitely normal, indeterminate, or definitely abnormal. Interobserver agreement regarding focal lesions was higher for CSE (κ=0.67) than for fast STIR (κ=0.57) but did not differ significantly. Of all focal lesions scored in consensus, 47 % were scored on both sequences, 31 % were only detected by fast STIR, and 22 % only by dual-echo CSE (n. s.). Interobserver agreement for diffuse abnormalities was lower with fast STIR (κ=0.48) than dual-echo CSE (κ=0.65; n. s.). After consensus, fast STIR showed in 10 patients diffuse abnormalities and dual-echo CSE in 3. After consensus, in 19 of 20 patients dual-echo CSE scans were considered as definitely abnormal compared with 17 for fast STIR. The fast STIR sequence is a useful adjunct to dual-echo CSE in detecting focal abnormalities and is helpful in detecting diffuse MS abnormalities in the spinal cord. Due to the frequent occurrence of artifacts and the lower observer concordance, fast STIR cannot be used alone. (orig.)

  9. [GC-MS combined with AMDIS and Kováts retention index to investigate dynamic change rules of volatile components from Atractylodis Macrocephalae Rhizoma with different stir-baking degrees].

    Science.gov (United States)

    Chen, Hong-Ping; Pan, Huan-Huan; Zhang, Xin; Liu, Fei; Chen, Mei-Jun; Luo, Guan-Hua; Liu, You-Ping

    2016-07-01

    To investigate the dynamic change rules of volatile components from Atractylodis Macrocephalae Rhizoma with different stir-baking degrees (from slight stir-baking, stir-baking to yellow, stir-baking to brown, to stir-baking to scorch). In the present experiment, the Atractylodis Macrocephalae Rhizoma samples with different stir-baking degrees were collected at different processing time points. The contents of volatile oil in various samples were determined by steam distillation method, and the volatile compounds were extracted by using static headspace sampling method. Gas chromatography-mass spectrography (GC-MS) and automated mass spectral deconrolution and identification system (AMDIS) were combined with Kováts retention index to analyze the chemical constituents of the volatile compounds. The results showed that with the deepening of the stir-baking degree, the content of volatile oil was decreased step by step in 4 phases, and both the compositions and contents of volatile components from Atractylodis Macrocephalae Rhizoma showed significant changes. The results showed that the dynamic change rules of volatile components from Atractylodis Macrocephalae Rhizoma in the process of stir-baking were closely related to the processing degree; in addition, Atractylodis Macrocephalae Rhizoma and honey bran had adsorption on each other. These results can provide a scientific basis for elucidating the stir-baking (with bran) mechanism of Atractylodis Macrocephalae Rhizoma. Copyright© by the Chinese Pharmaceutical Association.

  10. Speed and duration of walking and other leisure time physical activity and the risk of heart failure: a prospective cohort study from the Copenhagen City Heart Study.

    Directory of Open Access Journals (Sweden)

    Hans Askelund Saevereid

    Full Text Available AIM: Physical activity (PA confers some protection against development of heart failure (HF but little is known of the role of intensity and duration of exercise. METHODS AND RESULTS: In a prospective cohort study of men and women free of previous MI, stroke or HF with one or more examinations in 1976-2003, we studied the association between updated self-assessed leisure-time PA, speed and duration of walking and subsequent hospitalization or death from HF. Light and moderate/high level of leisure-time PA and brisk walking were associated with reduced risk of HF in both genders whereas no consistent association with duration of walking was seen. In 18,209 subjects age 20-80 with 1580 cases of HF, using the lowest activity level as reference, the confounder-adjusted hazard ratios (HR for light and moderate/high leisure-time physical activity were 0.75 (0.66-0.86 and 0.80 (0.69-0.93, respectively. In 9,937 subjects with information on walking available and 542 cases of HF, moderate and high walking speed were associated with adjusted HRs of 0.53 (0.43-0.66 and 0.30 (0.21-0.44, respectively, and daily walking of ½-1 hrs, 1-2 and >2 hrs with HR of 0.80 (0.61-1.06, 0.82 (0.62-1.06, and 0.96 (0.73-1.27, respectively. Results were similar for both genders and remained robust after exclusion of HF related to coronary heart disease and after a series of sensitivity analyses. CONCLUSIONS: Speed rather than duration of walking was associated with reduced risk of HF. Walking is the most wide-spread PA and public health measures to curb the increase in HF may benefit from this information.

  11. Speed of engagement with support generated by a smoking cessation smartphone Just In Time Adaptive Intervention (JITAI

    Directory of Open Access Journals (Sweden)

    Felix Naughton

    2015-10-01

    Full Text Available Background: An advantage of the high portability and sensing capabilities of smartphones is the potential for health apps to deliver advice and support to individuals close in time to when it is deemed of greatest relevance and impact, often referred to as Just In Time Adaptive Interventions (JITAI. However, little research has been undertaken to explore the viability of JITAI in terms of how long it takes users to engage with support triggered by real time data input, compared to scheduled support, and whether context affects response. This paper is focused on Q Sense, a smoking cessation app developed to deliver both Just in Time and scheduled support messages (every morning during a smoker’s quit attempt. The Just in Time cessation support generated by Q Sense is triggered by and tailored to real time context using location sensing. Objectives: To assess: 1 the time to engage with the app after a Just in Time support notification is delivered and whether this is influenced by the context in which the notification was initially delivered, 2 whether the time to engage with the app differs between Just in Time support notifications and scheduled support message notifications and 3 whether findings from objectives 1 and 2 differ between smokers receiving or not receiving NHS smoking cessation support. Methods: Data are from two studies evaluating the use of Q Sense: a feasibility study using an opportunity sample of smokers initiating a quit attempt with Q Sense without NHS cessation support (N=15 and an ongoing acceptability study of smokers receiving NHS smoking cessation support alongside app use (target N=40, recruitment due to be completed end of November 2015. Time elapse between notification generation and the user opening the app will be calculated and compared between message types (Just in Time vs. scheduled messages, contexts (home, work, socialising, other and samples (receiving or not receiving NHS cessation support using t

  12. Barbell-shaped stir bar sorptive extraction using dummy template molecularly imprinted polymer coatings for analysis of bisphenol A in water.

    Science.gov (United States)

    Liu, Ruimei; Feng, Feng; Chen, Guolin; Liu, Zhimin; Xu, Zhigang

    2016-07-01

    This study reports the development of a novel dummy template molecularly imprinted polymer (MIP)-coated barbell-shaped stir bar. The MIP stir bar coatings were prepared by using 2,2-bis(4-hydroxyphenyl)butane (BPB), 4,4'-dihydroxydiphenylmethane (BPF), 4-tert-butylphenol (PTBP), and tetrabromobisphenol A (TBBA) as dummy templates using a capillary in situ polymerization method. Uniform coatings can be prepared controllably. The method is simple, easy, and reproducible. The barbell-shaped stir bar was developed by using medical silicone tubes as wheels. The wheels could be removed and reinstalled when necessary; therefore, the barbell-shaped stir bar was easy to disassemble and reassemble. The novel MIP-coated stir bar showed good selectivity for the target analyte, bisphenol A (BPA). The established method is selective and sensitive with a lower detection limit for BPA of 0.003 μg/L. The dummy template MIP-coated stir bar is suitable for trace BPA analysis in real environmental water samples without template leakage. The novel stir bar can be used at least 100 times.

  13. TiB2 reinforced aluminum based in situ composites fabricated by stir casting

    International Nuclear Information System (INIS)

    Chen, Fei; Chen, Zongning; Mao, Feng; Wang, Tongmin; Cao, Zhiqiang

    2015-01-01

    In this study, a new technique involving mechanical stirring at the salts/aluminum interface was developed to fabricate TiB 2 particulate reinforced aluminum based in situ composites with improved particle distribution. Processing parameters in terms of stirring intensity, stirring duration and stirring start time were optimized according to the microstructure and mechanical properties evaluation. The results show that, the first and last 15 min of the entire 60 min holding are of prime importance to the particle distribution of the final composites. When applying 180 rpm (revolutions per minute) stirring at the salts/aluminum interface in these two intervals, a more uniform microstructure can be achieved and the Al-4 wt% TiB 2 composite thus produced exhibits superior mechanical performance. Synchrotron radiation X-ray computed tomography (SR-CT) was used to give a full-scale imaging of the particle distribution. From the SR-CT results, the in situ Al–xTiB 2 composites (x=1, 4 and 7, all in wt%) fabricated by the present technique are characterized by fine and clean TiB 2 particles distributed uniformly throughout the Al matrix. These composites not only have higher yield strength (σ 0.2 ) and ultimate tensile strength (UTS), but also exhibit superior ductility, with respect to the Al–TiB 2 composites fabricated by the conventional process. The σ 0.2 and UTS of the Al–7TiB 2 composite in the present work, are 260% and 180% higher than those of the matrix. A combined mechanism was also presented to interpret the improvements in yield strength of the composites as influenced by their microstructures and processing history. The predicted values are in good agreement with the experimental results, strongly supporting the strengthening mechanism we proposed. Fractography reveals that the composites thus fabricated, follow ductile fracture mechanism in spite of the presence of stiff reinforcements

  14. Chemical characterization and antioxidant activities comparison in fresh, dried, stir-frying and carbonized ginger.

    Science.gov (United States)

    Li, Yuxin; Hong, Yan; Han, Yanquan; Wang, Yongzhong; Xia, Lunzhu

    2016-02-01

    Ginger (Zingiber officinale Rosc.) is a common dietary adjunct that contributes to the taste and flavor of foods, and is also an important Traditional Chinese medicine (TCM). Different processing methods can produce different processed gingers with dissimilar chemical constituents and pharmacological activities. In this study, an ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC/QTOF-MS) was applied to identify the complicated components from fresh, dried, stir-frying and carbonized ginger extracts. All of the 27 compounds were identified from four kinds of ginger samples (fresh, dried, stir-frying and carbonized ginger). Five main constituents (zingerone, 6-gingerol, 8-gingerol, 6-shogaol and 10-gingerol) in these four kinds of ginger sample extracts were simultaneously determined by UPLC-PDA. Meanwhile, the antioxidant effect of fresh, dried, stir-frying and carbonized gingers were evaluated by three assays (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis(3-ethylbenzthiazolinesulfonic acid) diammonium salt (ABTS), and ferric reducing antioxidant power (FRAP)). The results demonstrated that antioxidant activity of dried ginger was the highest, for its phenolic contents are 5.2-, 1.1- and 2.4-fold higher than that of fresh, stir-frying and carbonized ginger, respectively, the antioxidant activities' results indicated a similar tendency with phenolic contents: dried ginger>stir-frying ginger>fresh ginger>carbonized ginger. The processing contributed to the decreased concentration of gingerols and the increased levels of shogaols, which reducing the antioxidant effects in pace with processing. This study elucidated the relationship of the heating process with the constituents and antioxidant activity, and provided a guide for choosing different kinds of ginger samples on clinical application. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Design and setup of a portable stirring device for transfer and dissolution of 99Mo applied to the use of a 99mTc generator

    International Nuclear Information System (INIS)

    Lopez, Yon; Rojas, Jorge

    2014-01-01

    This work shows the design and implementation of a portable magnetic stirring device for transfer and efficient dissolution of Mo O 3 coupled to a 99m Tc generator prototype. The development of this equipment will enable an efficient and safe transfer of 99 Mo at a 2 Ci of maximum activity from the nuclear reactor Huarangal to the point of operation of the 99m Tc generator equipment. This article describes the mechanical design, volume and shielding calculation, the electronics design and the programmable speed control of the stirring system for radioactive samples. (authors).

  16. Prediction of grain size and mechanical properties in friction stir welded pure copper joints using a thermal model

    DEFF Research Database (Denmark)

    Heidarzadeh, A.; Jabbaribehnam, Mirmasoud; Esmaily, M.

    2015-01-01

    In this study, a thermal model was developed and applied to simulate the friction stir welding of pure copper plates with the thickness of 2 mm. The different traverse speeds of 100, 200, 300, and 400 mm min−1 and rotational speeds of 400, 700, 900 rev min−1 were considered as welding parameters....... Microstructural characterization, hardness measurement, tensile test, and fractography were conducted experimentally. The comparison between the numerical and experimental results showed that the developed model was practically accurate. In addition, the results confirmed that the peak temperature...

  17. High-speed mapping of water isotopes and residence time in Cache Slough Complex, San Francisco Bay Delta, CA

    Data.gov (United States)

    Department of the Interior — Real-time, high frequency (1-second sample interval) GPS location, water quality, and water isotope (δ2H, δ18O) data was collected in the Cache Slough Complex (CSC),...

  18. On the speed towards the mean for continuous time autoregressive moving average processes with applications to energy markets

    International Nuclear Information System (INIS)

    Benth, Fred Espen; Taib, Che Mohd Imran Che

    2013-01-01

    We extend the concept of half life of an Ornstein–Uhlenbeck process to Lévy-driven continuous-time autoregressive moving average processes with stochastic volatility. The half life becomes state dependent, and we analyze its properties in terms of the characteristics of the process. An empirical example based on daily temperatures observed in Petaling Jaya, Malaysia, is presented, where the proposed model is estimated and the distribution of the half life is simulated. The stationarity of the dynamics yield futures prices which asymptotically tend to constant at an exponential rate when time to maturity goes to infinity. The rate is characterized by the eigenvalues of the dynamics. An alternative description of this convergence can be given in terms of our concept of half life. - Highlights: • The concept of half life is extended to Levy-driven continuous time autoregressive moving average processes • The dynamics of Malaysian temperatures are modeled using a continuous time autoregressive model with stochastic volatility • Forward prices on temperature become constant when time to maturity tends to infinity • Convergence in time to maturity is at an exponential rate given by the eigenvalues of the model temperature model

  19. Mechanical Properties Of AA 6061-T6 Aluminum Alloy Friction Stir Welds

    Directory of Open Access Journals (Sweden)

    Asmaa M. Abdullah

    2015-06-01

    Full Text Available The different parameters on mechanical and microstructural properties of aluminium alloy 6061-T6 Friction stir-welded (FSW joints were investigated in the present study. Different welded specimens were produced by employing variable rotating speeds and welding speeds. Tensile strength of the produced joints was tested at room temperature and the the effecincy was assessed, it was 75% of the base metal at rotational speed 1500 rpm and weld speed 50 mm/min. Hardness of various zones of FSW welds are presented and analyzed by means of brinell hardness number . Besides to thess tests the bending properties investigated and showed good results in some specimen and not in onother the mamximum stress was 240 N/mm2 at rotational speed 1500 rpm and weld speed 50 mm/min , while the maximum stress at 1250 rpm and 75 mm/min 94 N/mm2 , hardness results shwed lower values in heat affected and nugget zones than the base metal with improving of hardness at 1500 rpm, 75 mm/min .

  20. Delamination of hexagonal boron nitride in a stirred media mill

    International Nuclear Information System (INIS)

    Damm, C.; Körner, J.; Peukert, W.

    2013-01-01

    A scalable process for delamination of hexagonal boron nitride in an aqueous solution of the non-ionic surfactant TWEEN85 using a stirred media mill is presented. The size of the ZrO 2 beads used as grinding media governs the dimensions of the ground boron nitride particles as atomic force microscopic investigations (AFM) reveal: the mean flakes thickness decreases from 3.5 to 1.5 nm and the ratio between mean flake area and mean flake thickness increases from 2,200 to 5,800 nm if the grinding media size is reduced from 0.8 to 0.1 mm. This result shows that a high number of stress events in combination with low stress energy (small grinding media) facilitate delamination of the layered material whereas at high stress energies in combination with a low number of stress events (large grinding media) breakage of the layers dominates over delamination. The results of particle height analyses by AFM show that few-layer structures have been formed by stirred media milling. This result is in agreement with the layer thickness dependence of the delamination energy for hexagonal boron nitride. The concentration of nanoparticles remaining dispersed after centrifugation of the ground suspension increases with grinding time and with decreasing grinding media size. After 5 h of grinding using 0.1 mm ZrO 2 grinding media the yield of nanoparticle formation is about 5 wt%. The nanoparticles exhibit the typical Raman peak for hexagonal boron nitride at 1,366 cm −1 showing that the in-plane order in the milled platelets is remained.

  1. Speed mathematics

    CERN Document Server

    Handley, Bill

    2012-01-01

    This new, revised edition of the bestselling Speed Mathematics features new chapters on memorising numbers and general information, calculating statistics and compound interest, square roots, logarithms and easy trig calculations. Written so anyone can understand, this book teaches simple strategies that will enable readers to make lightning-quick calculations. People who excel at mathematics use better strategies than the rest of us; they are not necessarily more intelligent. With Speed Mathematics you'll discover methods to make maths easy and fun. This book is perfect for stud

  2. Building and analyzing models from data by stirred tank experiments for investigation of matrix effects caused by inorganic matrices and selection of internal standards in Inductively Coupled Plasma-Atomic Emission Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Grotti, Marco [Dipartimento di Chimica e Chimica Industriale, Via Dodecaneso 31, 16146 Genova (Italy)], E-mail: grotti@chimica.unige.it; Paredes, Eduardo; Maestre, Salvador; Todoli, Jose Luis [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, 03080, Alicante (Spain)

    2008-05-15

    Interfering effects caused by inorganic matrices (inorganic acids as well as easily ionized elements) in inductively coupled plasma-atomic emission spectroscopy have been modeled by regression analysis of experimental data obtained using the 'stirred tank method'. The main components of the experimental set-up were a magnetically-stirred container and two peristaltic pumps. In this way the matrix composition was gradually and automatically varied, while the analyte concentration remained unchanged throughout the experiment. An inductively coupled plasma spectrometer with multichannel detection based on coupled charge device was used to simultaneously measure the emission signal at several wavelengths when the matrix concentration was modified. Up to 50 different concentrations were evaluated in a period of time of 10 min. Both single interfering species (nitric, hydrochloric and sulphuric acids, sodium and calcium) and different mixtures (aqua regia, sulfonitric mixture, sodium-calcium mixture and sodium-nitric acid mixture) were investigated. The dependence of the emission signal on acid concentration was well-fitted by logarithmic models. Conversely, for the easily ionized elements, 3-order polynomial models were more suitable to describe the trends. Then, the coefficients of these models were used as 'signatures' of the matrix-related signal variations and analyzed by principal component analysis. Similarities and differences among the emission lines were highlighted and discussed, providing a new insight into the interference phenomena, mainly with regards to the combined effect of concomitants. The combination of the huge amount of data obtained by the stirred tank method in a short period of time and the speed of analysis of principal component analysis provided a judicious means for the selection of the optimal internal standard in inductively coupled plasma-atomic emission spectroscopy.

  3. Development of a high-speed real-time PCR system for rapid and precise nucleotide recognition

    Science.gov (United States)

    Terazono, Hideyuki; Takei, Hiroyuki; Hattori, Akihiro; Yasuda, Kenji

    2010-04-01

    Polymerase chain reaction (PCR) is a common method used to create copies of a specific target region of a DNA sequence and to produce large quantities of DNA. A few DNA molecules, which act as templates, are rapidly amplified by PCR into many billions of copies. PCR is a key technology in genome-based biological analysis, revolutionizing many life science fields such as medical diagnostics, food safety monitoring, and countermeasures against bioterrorism. Thus, many applications have been developed with the thermal cycling. For these PCR applications, one of the most important key factors is reduction in the data acquisition time. To reduce the acquisition time, it is necessary to decrease the temperature transition time between the high and low ends as much as possible. We have developed a novel rapid real-time PCR system based on rapid exchange of media maintained at different temperatures. This system consists of two thermal reservoirs and a reaction chamber for PCR observation. The temperature transition was achieved within 0.3 sec, and good thermal stability was achieved during thermal cycling with rapid exchange of circulating media. This system allows rigorous optimization of the temperatures required for each stage of the PCR processes. Resulting amplicons were confirmed by electrophoresis. Using the system, rapid DNA amplification was accomplished within 3.5 min, including initial heating and complete 50 PCR cycles. It clearly shows that the device could allow us faster temperature switching than the conventional conduction-based heating systems based on Peltier heating/cooling.

  4. Modeling Mental Speed: Decomposing Response Time Distributions in Elementary Cognitive Tasks and Correlations with Working Memory Capacity and Fluid Intelligence

    Directory of Open Access Journals (Sweden)

    Florian Schmitz

    2016-10-01

    Full Text Available Previous research has shown an inverse relation between response times in elementary cognitive tasks and intelligence, but findings are inconsistent as to which is the most informative score. We conducted a study (N = 200 using a battery of elementary cognitive tasks, working memory capacity (WMC paradigms, and a test of fluid intelligence (gf. Frequently used candidate scores and model parameters derived from the response time (RT distribution were tested. Results confirmed a clear correlation of mean RT with WMC and to a lesser degree with gf. Highly comparable correlations were obtained for alternative location measures with or without extreme value treatment. Moderate correlations were found as well for scores of RT variability, but they were not as strong as for mean RT. Additionally, there was a trend towards higher correlations for slow RT bands, as compared to faster RT bands. Clearer evidence was obtained in an ex-Gaussian decomposition of the response times: the exponential component was selectively related to WMC and gf in easy tasks, while mean response time was additionally predictive in the most complex tasks. The diffusion model parsimoniously accounted for these effects in terms of individual differences in drift rate. Finally, correlations of model parameters as trait-like dispositions were investigated across different tasks, by correlating parameters of the diffusion and the ex-Gaussian model with conventional RT and accuracy scores.

  5. An extra dimension to decision-making in animals: the three-way trade-off between speed, effort per-unit-time and accuracy.

    Science.gov (United States)

    de Froment, Adrian J; Rubenstein, Daniel I; Levin, Simon A

    2014-12-01

    The standard view in biology is that all animals, from bumblebees to human beings, face a trade-off between speed and accuracy as they search for resources and mates, and attempt to avoid predators. For example, the more time a forager spends out of cover gathering information about potential food sources the more likely it is to make accurate decisions about which sources are most rewarding. However, when the cost of time spent out of cover rises (e.g. in the presence of a predator) the optimal strategy is for the forager to spend less time gathering information and to accept a corresponding decline in the accuracy of its decisions. We suggest that this familiar picture is missing a crucial dimension: the amount of effort an animal expends on gathering information in each unit of time. This is important because an animal that can respond to changing time costs by modulating its level of effort per-unit-time does not have to accept the same decrease in accuracy that an animal limited to a simple speed-accuracy trade-off must bear in the same situation. Instead, it can direct additional effort towards (i) reducing the frequency of perceptual errors in the samples it gathers or (ii) increasing the number of samples it gathers per-unit-time. Both of these have the effect of allowing it to gather more accurate information within a given period of time. We use a modified version of a canonical model of decision-making (the sequential probability ratio test) to show that this ability to substitute effort for time confers a fitness advantage in the face of changing time costs. We predict that the ability to modulate effort levels will therefore be widespread in nature, and we lay out testable predictions that could be used to detect adaptive modulation of effort levels in laboratory and field studies. Our understanding of decision-making in all species, including our own, will be improved by this more ecologically-complete picture of the three-way tradeoff between time

  6. Microstructural features of friction stir welded dissimilar Aluminium alloys AA2219-AA7475

    Science.gov (United States)

    Zaman Khan, Noor; Ubaid, Mohammed; Siddiquee, Arshad Noor; Khan, Zahid A.; Al-Ahmari, Abdulrahman; Chen, Xizhang; Haider Abidi, Mustufa

    2018-05-01

    High strength, good corrosion resistance, light weight make aluminium alloys a material of choice in many industrial sectors like aerospace, marine etc. Problems associated with welding of these alloys by fusion welding processes restricted their use in various industries. Friction stir welding (FSW), a clean solid-state joining process, easily overcomes various difficulties encountered during conventional fusion welding processes. In the present work, the effect of rotational speed (710 rpm, 900 rpm and 1120 rpm) on micro-hardness distribution and microstructure of FSWed dissimilar aluminium alloy joints were analyzed. Plates of AA7475-T761 and AA2219-O having thickness of 2.5 mm were welded by fixing AA7475 on retreating side (RS) and AA2219 on advancing side (AS). Welded joints were characterized by Vickers micro-hardness testing, scanning electron microscopy (SEM) and optical microscopy (OM). Results revealed that rotational speed significantly affects the micro-hardness due to increase in grain size, coarsening and dissolution of strengthening precipitates and re-precipitation. Higher micro-hardness values were observed in stir zone due to grain refinement and re-precipitation. Minimum micro-hardness value was observed at the TMAZ/HAZ of advancing side due to thermal softening.

  7. Effect of process parameters on optimum welding condition of DP590 steel by friction stir welding

    International Nuclear Information System (INIS)

    Kim, Young Gon; Kim, Ji Sun; Kim, In Ju

    2014-01-01

    In the automotive industry, vehicle weight reduction techniques have been actively studied to improve the rate of fuel consumption and to cope with the regulation restricting exhaust gas. For this reason, advanced high-strength steel (AHSS) is preferred in the automobile industry as its tensile strength is 590 MPa and over. In this study, to obtain the optimum welding condition, the friction stir welding (FSW) process applied to AHSS was considered. The FSW experiment was performed on a stir plate using a Si 3 N 4 tool and a 1.4-mm thick DP590 steel sheet manufactured by cold rolling. In addition, to investigate the temperature distribution of the advancing and retreating sides in the welding state, the tool rotation speed of 800 rpm, and the welding speed of 180 mm/min, a K-type thermocouple was inserted in the backing plate, and the peak temperature was evaluated at each point. Especially, the correlation between the heat input per unit length and the formation of the FSW zone was minutely analyzed.

  8. Effect of process parameters on optimum welding condition of DP590 steel by friction stir welding

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Gon; Kim, Ji Sun; Kim, In Ju [Korea Institute of Industrial Technology, Gwangju (Korea, Republic of)

    2014-12-15

    In the automotive industry, vehicle weight reduction techniques have been actively studied to improve the rate of fuel consumption and to cope with the regulation restricting exhaust gas. For this reason, advanced high-strength steel (AHSS) is preferred in the automobile industry as its tensile strength is 590 MPa and over. In this study, to obtain the optimum welding condition, the friction stir welding (FSW) process applied to AHSS was considered. The FSW experiment was performed on a stir plate using a Si{sub 3}N{sub 4} tool and a 1.4-mm thick DP590 steel sheet manufactured by cold rolling. In addition, to investigate the temperature distribution of the advancing and retreating sides in the welding state, the tool rotation speed of 800 rpm, and the welding speed of 180 mm/min, a K-type thermocouple was inserted in the backing plate, and the peak temperature was evaluated at each point. Especially, the correlation between the heat input per unit length and the formation of the FSW zone was minutely analyzed.

  9. Friction stir weld assisted diffusion bonding of 5754 aluminum alloy to coated high strength steels

    International Nuclear Information System (INIS)

    Haghshenas, M.; Abdel-Gwad, A.; Omran, A.M.; Gökçe, B.; Sahraeinejad, S.; Gerlich, A.P.

    2014-01-01

    Highlights: • Successful lap joints of Al 5754 sheet to coated DP600 and 22MnB5 steels. • Negligible effect of welding speed on mechanical properties of Al 5754/22MnB5 joints. • Lower strength of Al 5754/22MnB5 joints compared with Al 5754/DP600 joints. - Abstract: In the present paper friction stir-induced diffusion bonding is used for joining sheets of 5754 aluminum alloy to coated high strength steels (DP600 and 22MnB5) by promoting diffusion bonding in an overlap configuration. Mechanical performance and microstructures of joints were analyzed by overlap shear testing, metallography, and X-ray diffraction. Our results show that the strength of joint is dependent upon tool travel speed and the depth of the tool pin relative to the steel surface. The thickness and types of intermetallic compounds formed at the interface play a significant role in achieving a joint with optimum performance. That is, the formation of high aluminum composition intermetallic compounds (i.e. Al 5 Fe 2 ) at the interface of the friction stir lap joint appeared to have a more negative effect on joint strength compared to the presence of high iron composition intermetallic phases (i.e. FeAl). This is in agreement with previously reported findings that FeAl intermetallic can improve the fracture toughness and interface strength in Al/St joints

  10. Predicting tensile strength of friction stir welded AA6061 aluminium alloy joints by a mathematical model

    International Nuclear Information System (INIS)

    Elangovan, K.; Balasubramanian, V.; Babu, S.

    2009-01-01

    AA6061 aluminium alloy (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to weight ratio and good corrosion resistance. Compared to the fusion welding processes that are routinely used for joining structural aluminium alloys, friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt and recast. This process uses a non-consumable tool to generate frictional heat in the abutting surfaces. The welding parameters such as tool rotational speed, welding speed, axial force etc., and tool pin profile play a major role in deciding the joint strength. An attempt has been made to develop a mathematical model to predict tensile strength of the friction stir welded AA6061 aluminium alloy by incorporating FSW process parameters. Four factors, five levels central composite design has been used to minimize number of experimental conditions. Response surface method (RSM) has been used to develop the model. Statistical tools such as analysis of variance (ANOVA), student's t-test, correlation co-efficient etc. have been used to validate the developed model. The developed mathematical model can be effectively used to predict the tensile strength of FSW joints at 95% confidence level

  11. Influence of Friction Stir Welding on Mechanical Properties of Butt Joints of AZ61 Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Seung-Ju Sun

    2017-01-01

    Full Text Available In this study, the effect of heat input on the mechanical properties and fracture behaviors of AZ61 magnesium alloy joints has been studied. Magnesium alloy AZ61 plates with thickness of 5 mm were welded at different ratios of tool rotational speed to welding speed (ω/ν. The average ultimate tensile strength of all weld conditions satisfying a ω/ν ratio of 3 reached 100% of the strength of the base material. Fractures occurred at the interface between the thermomechanical affected zone at advancing side and the stir zone in all welded specimens. From the scanning electron microscope and electron backscatter diffraction analysis, it was determined that the interface between the thermomechanical affected zone and the stir zone, which is the region where the grain orientation changes, was the weakest part; the advancing side region was relatively weaker than the retreating side region because the grain orientation change occurred more dramatically in the advancing side region.

  12. Development of liquid-nitrogen-cooling friction stir spot welding for AZ31 magnesium alloy joints

    Science.gov (United States)

    Wu, Dong; Shen, Jun; Zhou, Meng-bing; Cheng, Liang; Sang, Jia-xing

    2017-10-01

    A liquid-nitrogen-cooling friction stir spot welding (C-FSSW) technology was developed for welding AZ31 magnesium alloy sheets. The liquid-nitrogen cooling degraded the deformability of the welded materials such that the width of interfacial cracks increased with increasing cooling time. The grain size of the stirred zone (SZ) and the heat-affected zone (HAZ) of the C-FSSW-welded joints decreased, whereas that of the thermomechanically affected zone (TMAZ) increased with increasing cooling time. The maximum tensile shear load of the C-FSSW-welded joints welded with a cooling time of 5 or 7 s was larger than that of the friction stir spot welding (FSSW)-welded joint, and the tensile shear load decreased with increasing cooling time. The microhardness of the C-FSSW-welded joints was greater than that of the FSSW-welded joint. Moreover, the microhardness of the SZ and the HAZ of the C-FSSW-welded joints increased, whereas that of the TMAZ decreased, with increasing cooling time.

  13. Thermomechanical Modelling of Friction Stir Welding

    DEFF Research Database (Denmark)

    Hattel, Jesper Henri; Schmidt, Henrik Nikolaj Blicher; Tutum, Cem Celal

    2009-01-01

    Friction Stir Welding (FSW) is a fully coupled thermomechanical process and should in general be modelled as such. Basically, there are two major application areas of thermomechanical models in the investigation of the FSW process: i) Analysis of the thermomechanical conditions such as e.g. heat...... generation and local material deformation (often referred to as flow) during the welding process itself. ii) Prediction of the residual stresses that will be present in the joint structure post to welding. While the former in general will call for a fully-coupled thermomechanical procedure, however...... for the FSW process at hand, the heat generation must either be prescribed analytically or based on a fully coupled analysis of the welding process itself. Along this line, a recently proposed thermal-pseudo-mechanical model is presented in which the temperature dependent yield stress of the weld material...

  14. Ultrasonically-assisted Thermal Stir Welding System

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2014-01-01

    A welding head assembly has a work piece disposed between its containment plates' opposing surfaces with the work piece being maintained in a plastic state thereof at least in a vicinity of the welding head assembly's stir rod as the rod is rotated about its longitudinal axis. The welding head assembly and the work piece experience relative movement there between in a direction perpendicular to the rod's longitudinal axis as the work piece is subjected to a compressive force applied by the containment plates. A first source coupled to the first containment plate applies a first ultrasonic wave thereto such that the first ultrasonic wave propagates parallel to the direction of relative movement. A second source coupled to the second containment plate applies a second ultrasonic wave thereto such that the second ultrasonic wave propagates parallel to the direction of relative movement.propagates parallel to the direction of relative movement.

  15. Unstable Temperature Distribution in Friction Stir Welding

    Directory of Open Access Journals (Sweden)

    Sadiq Aziz Hussein

    2014-01-01

    Full Text Available In the friction stir welding process, a nonuniform and high generated temperature is undesirable. Unstable temperature and distribution affect thermal and residual stresses along the welding line, thus necessitating mitigation. This paper presents a simple method to prevent significant temperature difference along the welding line and also to help nullifying some defect types associated with this welding, such as end-hole, initial unwelded line, and deformed areas. In the experimental investigation, a heat and force thermocouple and dynamometer were utilized while couple-field thermomechanical models were used to evaluate temperature and its distribution, plastic strain, and material displacement. The suggested method generated uniform temperature distributions. Measurement results are discussed, showing a good correlation with predictions.

  16. Friction stir welding sets sail in China

    International Nuclear Information System (INIS)

    Luan, Guohong

    2007-01-01

    Today, Friction Stir Welding has set sail in China. As the pioneer of FSW development in the China territory, China FSW Centre hes made outstanding achievements in FSW technique development, FSW engineering, FSW equipment and FSW product. But the real industrial applications of FSW in China are just begining. With the planned national long-term development programmes and huge market requirement in aerospace, aviation, shipbuilding, railway, power and energy industries, FSW will continue to develop rapidly in the next 10 years. FSW will continue to develop rapidly in the next 10 years. FSW not only raises the level of joining techniques in Chinese industrial companies, but also increase the competitive ability of the industrial products made in china

  17. Metal Flow in Friction Stir Welding

    Science.gov (United States)

    Nunes, Arthur C., Jr.

    2006-01-01

    The plastic deformation field in Friction Stir Welding (FSW) is compared to that in metal cutting. A shear surface around the FSW tool analogous to the metal cutting shear plane is identified and comprises the basis of the "rotating plug" flow field model and the "wiping" model of tool interaction with weld metal. Within the context of these models: The FSW shear rate is estimated to be comparable to metal cutting shear rates. The effect of tool geometry on the FSW shear surface is discussed and related to published torque measurements. Various FS W structural features are explained, including a difference in structure of bimetallic welds when alloys on the advancing and retreating sides of the weld seam are exchanged. The joining mechanism and critical parameters of the FSW process are made clear.

  18. Development of a carbon-nanoparticle-coated stirrer for stir bar sorptive extraction by a simple carbon deposition in flame.

    Science.gov (United States)

    Feng, Juanjuan; Sun, Min; Bu, Yanan; Luo, Chuannan

    2016-03-01

    Stir bar sorptive extraction is an environmentally friendly microextraction technique based on a stir bar with various sorbents. A commercial stirrer is a good support, but it has not been used in stir bar sorptive extraction due to difficult modification. A stirrer was modified with carbon nanoparticles by a simple carbon deposition process in flame and characterized by scanning electron microscopy and energy-dispersive X-ray spectrometry. A three-dimensional porous coating was formed with carbon nanoparticles. In combination with high-performance liquid chromatography, the stir bar was evaluated using five polycyclic aromatic hydrocarbons as model analytes. Conditions including extraction time and temperature, ionic strength, and desorption solvent were investigated by a factor-by-factor optimization method. The established method exhibited good linearity (0.01-10 μg/L) and low limits of quantification (0.01 μg/L). It was applied to detect model analytes in environmental water samples. No analyte was detected in river water, and five analytes were quantified in rain water. The recoveries of five analytes in two samples with spiked at 2 μg/L were in the range of 92.2-106% and 93.4-108%, respectively. The results indicated that the carbon nanoparticle-coated stirrer was an efficient stir bar for extraction analysis of some polycyclic aromatic hydrocarbons. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Examination of the rheological properties of stirred joghurt during the long-term storage by using dynamic oscillation method

    Directory of Open Access Journals (Sweden)

    Milica Vilušić

    2003-07-01

    Full Text Available In this work the rheological properties of stirred yoghurt during the longterm storage at 4 and 8°C were investigated. The optimal quantity of additives, in order to increase dry matter content (whole milk powder and whey protein-lactalbumin, was preliminary determined and the fermentation was performed. During 42 days, i.e., 1st, 7th, 14th, 21st, 28th, 35th and 42nd day of storage of stirred yoghurt, in refrigerator at 4 and 8°C, the changes of pH value, acidity and rheological properties by using of dynamic oscillation method were observed. Results of this work indicated that an addition of whole milk powder and whey protein have an influence on rheological properties of stirred yoghurt. The long-term storage of stirred yoghurt and the results of dynamic oscilations showed permanently higher G’storage (elasticity modulus, where elastic properties of viscoelastic products dominate, in comparison with the G” loss (viscosity modulus. Increased moduls of elasticy and viscosity, as function of time, permanently occurs at pH value 4.00 and lower, as an indication of alteration of long casein chains in the coagulum structure. Different temperatures of storage had no influence on changes of rheological properties of examinated types of stirred yoghur. The relation of above mentioned moduls of elasticy and viscosity kept the same increasing tendency.

  20. Origin of unusual fracture in stirred zone for friction stir welded 2198-T8 Al-Li alloy joints

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Y. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Ni, D.R., E-mail: drni@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Xiao, B.L.; Ma, Z.Y. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Wu, W.; Zhang, R.X. [AVIC Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024 (China); Zeng, Y.S., E-mail: yszeng@hotmail.com [AVIC Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024 (China)

    2017-05-02

    Friction stir welded (FSW) joints of conventional precipitation-hardened aluminum alloys usually fracture in the lowest hardness zone (LHZ) during tension testing. However, all of the FSW joints of a 2198-T8 Al-Li alloy fractured in the stirred zone (SZ) instead of the LHZ with the welding parameters of 800 rpm-200 mm/min and 1600 rpm-200 mm/min under the condition that no welding defects existed in the SZ. The experiment results revealed that lazy S was not the dominant factor resulting in the unusual fracture. The SZ consisted of three subzones, i.e., the shoulder-affected zone, the pin-affected zone, and the transition zone between them. While the former two zones were characterized by fine and equiaxed recrystallized grains, incompletely dynamically recrystallized microstructure containing coarse elongated non-recrystallized grains was observed in the transition zone. The transition zone exhibited the lowest average Taylor factor in the SZ, resulting in a region that was crystallographically weak. Furthermore, obvious lithium segregation at grain boundaries was observed in the transition zone via time-of-flight secondary ion mass spectroscopy analysis, but not in the shoulder-affected zone or the pin-affected zone. The combined actions of both the two factors resulted in the appearance of preferential intergranular fracture in the transition zone and eventually caused the failure in the SZ. The lithium segregation at grain boundaries in the transition zone was closely associated with both the segregation in the base material and the partially dynamically recrystallized microstructure resulting from the inhomogeneous plastic deformation in the SZ.