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Sample records for rolls size effects

  1. Influences Of Size Effects On The Rolling Of Micro Strip

    NASA Astrophysics Data System (ADS)

    van Putten, Koos; Kopp, Reiner; Hirt, Gerhard

    2007-04-01

    Comparison between down-scaled flat rolling experiments of thin round wire and numerical simulation of those experiments have shown that the production process of manufacturing micro strip out of thin round wire is influenced by size effects. From plane strain compression tests, used as a physical simulation of the rolling process it is concluded that second order size effects of mechanical strength cause decreasing resistance to forming with decreasing wire diameters for rolling experiments with 25% and 50% reduction.

  2. Influences Of Size Effects On The Rolling Of Micro Strip

    SciTech Connect

    Putten, Koos van; Kopp, Reiner; Hirt, Gerhard

    2007-04-07

    Comparison between down-scaled flat rolling experiments of thin round wire and numerical simulation of those experiments have shown that the production process of manufacturing micro strip out of thin round wire is influenced by size effects. From plane strain compression tests, used as a physical simulation of the rolling process it is concluded that second order size effects of mechanical strength cause decreasing resistance to forming with decreasing wire diameters for rolling experiments with 25% and 50% reduction.

  3. Size Effect on Mechanical Properties and Texture of Pure Copper Foil by Cold Rolling

    PubMed Central

    Song, Meng; Liu, Xianghua; Liu, Lizhong

    2017-01-01

    To study the size effect on the properties of copper, tensile tests were performed with pure copper foil (thickness range from 25 μm to 300 μm) by cold rolling. A pronounced size effect was observed at a thickness of 76 μm. The results showed that ultimate strength increased as sample thickness decreased from 300 μm to 100 μm, however, this was decreased as the thickness changed from 76 μm to 25 μm with ultrahigh strain, with the same trend of dislocation density and micro stain. The rolling texture were consisted of copper {112}<111>, brass {011}<211>, and S {123}<634>. These features seemed to be linked to the increase of fraction of surface grain to volume, which led to lower districting on the dislocation slip. PMID:28772898

  4. Effect of roll hot press temperature on crystallite size of PVDF film

    SciTech Connect

    Hartono, Ambran Sanjaya, Edi; Djamal, Mitra; Satira, Suparno; Bahar, Herman; Ramli

    2014-03-24

    Fabrication PVDF films have been made using Hot Roll Press. Preparation of samples carried out for nine different temperatures. This condition is carried out to see the effect of Roll Hot Press temperature on the size of the crystallite of PVDF films. To obtain the diffraction pattern of sample characterization is performed using X-Ray Diffraction. Furthermore, from the diffraction pattern is obtained, the calculation to determine the crystallite size of the sample by using the Scherrer equation. From the experimental results and the calculation of crystallite sizes obtained for the samples with temperature 130 °C up to 170 °C respectively increased from 7.2 nm up to 20.54 nm. These results show that increasing temperatures will also increase the size of the crystallite of the sample. This happens because with the increasing temperature causes the higher the degree of crystallization of PVDF film sample is formed, so that the crystallite size also increases. This condition indicates that the specific volume or size of the crystals depends on the magnitude of the temperature as it has been studied by Nakagawa.

  5. Phase transformation kinetics in rolled U-10 wt. % Mo foil: Effect of post-rolling heat treatment and prior γ-UMo grain size

    DOE PAGES

    Jana, Saumyadeep; Overman, Nicole; Varga, Tamas; ...

    2017-09-25

    Here, the effect of sub-eutectoid heat treatment on the phase transformation behavior in rolled U-10 wt.% Mo (U10Mo) foils was systematically investigated. The as-cast 5 mm thick foils were initially homogenized at 900 °C for 48 h and were hot rolled to 2 mm and later cold rolled down to 0.2 mm. Three starting microstructures were evaluated: (i) hot + cold-rolled to 0.2 mm (as-rolled condition), (ii) hot + cold-rolled to 0.2 mm + annealed at 700 °C for 1 h, and (iii) hot + cold-rolled to 0.2 mm + annealed at 1000 °C for 60 h. Annealing of as-rolledmore » materials at 700 °C resulted in small grain size (15 ± 9 μm average grain size), while annealing at 1000 °C led to very large grains (156 ± 118 μm average grain size) in rolled U10Mo foils. Later the samples were subjected to sub-eutectoid heat-treatment temperatures of 550 °C, 500 °C, and 400 °C for different durations of time starting from 1 h up to 100 h. U10Mo rolled foils went through various degrees of decomposition when subjected to the sub-eutectoid heat-treatment step and formed a lamellar microstructure through a cellular reaction mostly along the previous γ-UMo grain boundaries. The least amount of cellular reaction was observed in the large-grain microstructure at all temperatures. Conversely, a substantial amount of cellular reaction was observed in both the as-rolled and the small-grain microstructure. After 100 h of heat treatment at 500 °C, the volume fraction of the lamellar phase was found to be 4%, 22%, and 82% in large-grain, as-rolled, and small-grain samples, respectively.« less

  6. Effect of carbide size, area, density on rolling-element fatigue

    NASA Technical Reports Server (NTRS)

    Chevalier, J. L.; Zaretsky, E. V.

    1972-01-01

    A carbide parameter that can be used to predict rolling element fatigue life was developed.The parameter is based on a statistical life analysis and incorporates the total number of particles per unit area, particle size, and percent carbide area. These were determined from quantimet image analyzing computer examinations of random samples selected from eight lots of material previously tested in rolling fatigue. The carbide parameter is independent of chemical composition, heat treatment, and hardening mechanism of the materials investigated.

  7. Multi-passes warm rolling of AZ31 magnesium alloy, effect on evaluation of texture, microstructure, grain size and hardness

    NASA Astrophysics Data System (ADS)

    Kamran, J.; Hasan, B. A.; Tariq, N. H.; Izhar, S.; Sarwar, M.

    2014-06-01

    In this study the effect of multi-passes warm rolling of AZ31 magnesium alloy on texture, microstructure, grain size variation and hardness of as cast sample (A) and two rolled samples (B & C) taken from different locations of the as-cast ingot was investigated. The purpose was to enhance the formability of AZ31 alloy in order to help manufacturability. It was observed that multi-passes warm rolling (250°C to 350°C) of samples B & C with initial thickness 7.76mm and 7.73 mm was successfully achieved up to 85% reduction without any edge or surface cracks in ten steps with a total of 26 passes. The step numbers 1 to 4 consist of 5, 2, 11 and 3 passes respectively, the remaining steps 5 to 10 were single pass rolls. In each discrete step a fixed roll gap is used in a way that true strain per step increases very slowly from 0.0067 in the first step to 0.7118 in the 26th step. Both samples B & C showed very similar behavior after 26th pass and were successfully rolled up to 85% thickness reduction. However, during 10th step (27th pass) with a true strain value of 0.772 the sample B experienced very severe surface as well as edge cracks. Sample C was therefore not rolled for the 10th step and retained after 26 passes. Both samples were studied in terms of their basal texture, microstructure, grain size and hardness. Sample C showed an equiaxed grain structure after 85% total reduction. The equiaxed grain structure of sample C may be due to the effective involvement of dynamic recrystallization (DRX) which led to formation of these grains with relatively low misorientations with respect to the parent as cast grains. The sample B on the other hand showed a microstructure in which all the grains were elongated along the rolling direction (RD) after 90 % total reduction and DRX could not effectively play its role due to heavy strain and lack of plastic deformation systems. The microstructure of as cast sample showed a near-random texture (mrd 4.3), with average grain size

  8. Effect of roll compaction on granule size distribution of microcrystalline cellulose–mannitol mixtures: computational intelligence modeling and parametric analysis

    PubMed Central

    Kazemi, Pezhman; Khalid, Mohammad Hassan; Pérez Gago, Ana; Kleinebudde, Peter; Jachowicz, Renata; Szlęk, Jakub; Mendyk, Aleksander

    2017-01-01

    Dry granulation using roll compaction is a typical unit operation for producing solid dosage forms in the pharmaceutical industry. Dry granulation is commonly used if the powder mixture is sensitive to heat and moisture and has poor flow properties. The output of roll compaction is compacted ribbons that exhibit different properties based on the adjusted process parameters. These ribbons are then milled into granules and finally compressed into tablets. The properties of the ribbons directly affect the granule size distribution (GSD) and the quality of final products; thus, it is imperative to study the effect of roll compaction process parameters on GSD. The understanding of how the roll compactor process parameters and material properties interact with each other will allow accurate control of the process, leading to the implementation of quality by design practices. Computational intelligence (CI) methods have a great potential for being used within the scope of quality by design approach. The main objective of this study was to show how the computational intelligence techniques can be useful to predict the GSD by using different process conditions of roll compaction and material properties. Different techniques such as multiple linear regression, artificial neural networks, random forest, Cubist and k-nearest neighbors algorithm assisted by sevenfold cross-validation were used to present generalized models for the prediction of GSD based on roll compaction process setting and material properties. The normalized root-mean-squared error and the coefficient of determination (R2) were used for model assessment. The best fit was obtained by Cubist model (normalized root-mean-squared error =3.22%, R2=0.95). Based on the results, it was confirmed that the material properties (true density) followed by compaction force have the most significant effect on GSD. PMID:28176905

  9. Effect of roll compaction on granule size distribution of microcrystalline cellulose-mannitol mixtures: computational intelligence modeling and parametric analysis.

    PubMed

    Kazemi, Pezhman; Khalid, Mohammad Hassan; Pérez Gago, Ana; Kleinebudde, Peter; Jachowicz, Renata; Szlęk, Jakub; Mendyk, Aleksander

    2017-01-01

    Dry granulation using roll compaction is a typical unit operation for producing solid dosage forms in the pharmaceutical industry. Dry granulation is commonly used if the powder mixture is sensitive to heat and moisture and has poor flow properties. The output of roll compaction is compacted ribbons that exhibit different properties based on the adjusted process parameters. These ribbons are then milled into granules and finally compressed into tablets. The properties of the ribbons directly affect the granule size distribution (GSD) and the quality of final products; thus, it is imperative to study the effect of roll compaction process parameters on GSD. The understanding of how the roll compactor process parameters and material properties interact with each other will allow accurate control of the process, leading to the implementation of quality by design practices. Computational intelligence (CI) methods have a great potential for being used within the scope of quality by design approach. The main objective of this study was to show how the computational intelligence techniques can be useful to predict the GSD by using different process conditions of roll compaction and material properties. Different techniques such as multiple linear regression, artificial neural networks, random forest, Cubist and k-nearest neighbors algorithm assisted by sevenfold cross-validation were used to present generalized models for the prediction of GSD based on roll compaction process setting and material properties. The normalized root-mean-squared error and the coefficient of determination (R(2)) were used for model assessment. The best fit was obtained by Cubist model (normalized root-mean-squared error =3.22%, R(2)=0.95). Based on the results, it was confirmed that the material properties (true density) followed by compaction force have the most significant effect on GSD.

  10. Effects of wing position and fuselage size on the low-speed static rolling stability characteristics of a delta-wing model

    NASA Technical Reports Server (NTRS)

    Goodman, Alex; Thomas, David T , Jr

    1955-01-01

    An investigation was made to determine the effects of wing position and fuselage size on the low-speed static and rolling stability characteristics of airplane models having a triangular wing and vertical tail surfaces. (author)

  11. The Effect of Oat Fibre Powder Particle Size on the Physical Properties of Wheat Bread Rolls

    PubMed Central

    Kurek, Marcin; Wyrwisz, Jarosław; Piwińska, Monika; Wierzbicka, Agnieszka

    2016-01-01

    Summary In response to the growing interest of modern society in functional food products, this study attempts to develop a bakery product with high dietary fibre content added in the form of an oat fibre powder. Oat fibre powder with particle sizes of 75 µm (OFP1) and 150 µm (OFP2) was used, substituting 4, 8, 12, 16 and 20% of the flour. The physical properties of the dough and the final bakery products were then measured. Results indicated that dough with added fibre had higher elasticity than the control group. The storage modulus values of dough with OFP1 most closely approximated those of the control group. The addition of OFP1 did not affect significantly the colour compared to the other samples. Increasing the proportion of oat fibre powder resulted in increased firmness, which was most prominent in wheat bread rolls with oat fibre powder of smaller particle sizes. The addition of oat fibre powder with smaller particles resulted in a product with the rheological and colour parameters that more closely resembled control sample. PMID:27904392

  12. Effect of Particle Size on the Mechanical Properties of Semi-Solid, Powder-Rolled AA7050 Strips

    NASA Astrophysics Data System (ADS)

    Luo, Xia; Liu, Yunzhong

    2016-12-01

    The AA7050 alloy strips can be successfully prepared by semi-solid powder rolling. The effect and factors of particle size on the microstructure, relative density, and mechanical properties were discussed. The results show that coarse starting powders require less liquid to achieve high relative density, and the formed strips have lower elongation compared with that prepared with the fine starting powders. The strength is more related to defects, whereas elongation partially depends on the grain size. Additionally, the fracture mechanism of strips prepared with fine powders is the ductile fracture because many dimples are observed. For relative density, when the initial liquid fraction is lower than 10%, the difference of deformation degree is the main factor. When the liquid fraction is higher than 10-20%, premature solidification and more particle interfaces are the two main factors.

  13. Effect of Roll Material on Surface Quality of Rolled Aluminum

    NASA Astrophysics Data System (ADS)

    Zhao, Qi

    The surface defects of aluminum alloys that have undergone hot rolling were studied. The effects of different roll materials, of the number of rolling passes and of lubrication on surface defects of hot rolled aluminum alloys were investigated by laboratory hot rolling. Two different aluminum alloys, Al-Mn and Al-Mg, were each rolled against three different steel alloy rolls, AISI 52100, AISI 440C and AISI D2. The results showed that different roll materials do affect the morphology of the mating aluminum alloy surface with apparent surface defects, which included magnesium and oxygen rich dark regions on both alloys. The carbide protrusions in 440C and D2 steel rolls are confirmed to be responsible for the dark, rich magnesium and oxygen regions on both the rolled Al-Mn and Al-Mg alloy surfaces. As the number of passes increases, Mg and O deposit in the form of patches and grain boundaries near the surface area.

  14. Effect of texture and grain size on the magnetic flux density and core loss of cold-rolled high silicon steel sheets

    NASA Astrophysics Data System (ADS)

    Qin, Jing; Yang, Ping; Mao, Weimin; Ye, Feng

    2015-11-01

    The effects of texture and grain size on the magnetic flux density and core loss (50-20 kHz) of 0.23 mm-thick cold-rolled high silicon steel sheets are investigated by means of electron back-scattered diffraction (EBSD), loss separation, and anisotropy parameter (ε) calculation. A model of the hysteresis loss coefficient kh considering average grain size and ε is established. The magnetic flux density at 800 A/m (B8) is closely related to the volume fraction of η-fiber-oriented grains, while the magnetic flux density at 5000 A/m (B50) is closely related to the volume fractions of γ- and λ-fiber-oriented grains in high silicon steel. The hysteresis loss of high silicon steel can be greatly reduced by increasing the grain size and optimizing the texture of the sheets. Although increases in frequencies decrease the effect of texture on core loss, the effect cannot be ignored. As annealing temperature and time increase, the relative difference in core loss between the rolling direction (RD) and the transverse direction (TD) is maintained at higher frequencies because of increases in grain size, decreases in γ texture, and maintenance of a strong η texture. Texture and grain size jointly affect the high-frequency core loss of high silicon steel.

  15. Effect of field size, head motion, and rotational velocity on roll vection and illusory self-tilt in a tumbling room

    NASA Technical Reports Server (NTRS)

    Allison, R. S.; Howard, I. P.; Zacher, J. E.; Oman, C. M. (Principal Investigator)

    1999-01-01

    The effect of field size, velocity, and visual fixation upon the perception of self-body rotation and tilt was examined in a rotating furnished room. Subjects sat in a stationary chair in the furnished room which could be rotated about the body roll axis. For full-field conditions, complete 360 degrees body rotation (tumbling) was the most common sensation (felt by 80% of subjects). Constant tilt or partial tumbling (less than 360 degrees rotation) occurred more frequently with a small field of view (20 deg). The number of subjects who experienced complete tumbling increased with increases in field of view and room velocity (for velocities between 15 and 30 degrees s-1). The speed of perceived self-rotation relative to room rotation also increased with increasing field of view.

  16. The effects of dry-rolled corn particle size on performance, carcass traits, and starch digestibility in feedlot finishing diets containing wet distiller's grains.

    PubMed

    Schwandt, E F; Wagner, J J; Engle, T E; Bartle, S J; Thomson, D U; Reinhardt, C D

    2016-03-01

    Crossbred yearling steers ( = 360; 395 ± 33.1 kg initial BW) were used to evaluate the effects of dry-rolled corn (DRC) particle size in diets containing 20% wet distiller's grains plus solubles on feedlot performance, carcass characteristics, and starch digestibility. Steers were used in a randomized complete block design and allocated to 36 pens (9 pens/treatment, with 10 animals/pen). Treatments were coarse DRC (4,882 μm), medium DRC (3,760 μm), fine DRC (2,359 μm), and steam-flaked corn (0.35 kg/L; SFC). Final BW and ADG were not affected by treatment ( > 0.05). Dry matter intake was greater and G:F was lower ( < 0.05) for steers fed DRC vs. steers fed SFC. There was a linear decrease ( < 0.05) in DMI in the final 5 wk on feed with decreasing DRC particle size. Fecal starch decreased (linear, < 0.01) as DRC particle size decreased. In situ starch disappearance was lower for DRC vs. SFC ( < 0.05) and linearly increased ( < 0.05) with decreasing particle size at 8 and 24 h. Reducing DRC particle size did not influence growth performance but increased starch digestion and influenced DMI of cattle on finishing diets. No differences ( > 0.10) were observed among treatments for any of the carcass traits measured. Results indicate improved ruminal starch digestibility, reduced fecal starch concentration, and reduced DMI with decreasing DRC particle size in feedlot diets containing 20% wet distiller's grains on a DM basis.

  17. The Effects of Forming Parameters on Conical Ring Rolling Process

    PubMed Central

    Meng, Wen; Zhao, Guoqun; Guan, Yanjin

    2014-01-01

    The plastic penetration condition and biting-in condition of a radial conical ring rolling process with a closed die structure on the top and bottom of driven roll, simplified as RCRRCDS, were established. The reasonable value range of mandrel feed rate in rolling process was deduced. A coupled thermomechanical 3D FE model of RCRRCDS process was established. The changing laws of equivalent plastic strain (PEEQ) and temperature distributions with rolling time were investigated. The effects of ring's outer radius growth rate and rolls sizes on the uniformities of PEEQ and temperature distributions, average rolling force, and average rolling moment were studied. The results indicate that the PEEQ at the inner layer and outer layer of rolled ring are larger than that at the middle layer of ring; the temperatures at the “obtuse angle zone” of ring's cross-section are higher than those at “acute angle zone”; the temperature at the central part of ring is higher than that at the middle part of ring's outer surfaces. As the ring's outer radius growth rate increases at its reasonable value ranges, the uniformities of PEEQ and temperature distributions increase. Finally, the optimal values of the ring's outer radius growth rate and rolls sizes were obtained. PMID:25202716

  18. Roll bar x-ray spot size measurement technique

    SciTech Connect

    Richardson, R. A.; Houck, T. L.

    1998-08-14

    A time dependent x-ray spot size measurement is critical to understanding beam target physics such as target plasma generated beam instabilities. The so-called roll bar measurement uses a heavy metal material which is optically thick to X-rays, to form a 1D shadow of the x-ray origination spot. This spot is where an energetic electron beam interacts with a high Z target to produce the x-rays. The material (the "roll bar") has a slight radius to avoid alignment problems. If a beam profile is assumed (or measured by other means), the equivalent x-ray spot size can be calculated from the x-ray shadow cast by the roll bar. Typically a radiographic film is exposed over the duration of the beam pulse, and the shadow is analyzed for a time integrated measurement. This paper explores various techniques to convert the x-rays to visible photons which can be imaged using a gated camera or streak camera for time evolved x-ray spot size. Data will be presented from the measurements on the ETA II induction linac.

  19. Effect of temper rolling on final shape defects in a V-section roll forming process

    NASA Astrophysics Data System (ADS)

    Abvabi, Akbar; Rolfe, Bernard; Hodgson, Peter D.; Weiss, Matthias

    2013-12-01

    Roll forming is a continuous process in which a flat strip is shaped to the desired profile by sequential bending in a series of roll stands. Because of the large variety of applications of roll forming in the industry, Finite Element Analysis (FEA) is increasingly utilized for roll forming process design. Bending is the dominant deformation mode in roll forming. Sheet materials used in this process are generally temper rolled, roller- or tension- leveled. These processes introduce residual stresses into the material, and recent studies have shown that those affect the material behavior in bending. In this study a numerical model of the temper rolling (skin passing) process was used to determine a residual stress distribution in a dual phase, DP780, steel strip. A 5-stand roll forming process for the forming of a V-section was modeled, and the effect of various thickness reduction levels in the temper rolling process on the final shape defects was analyzed. The results show that a small thickness reduction in the temper rolling process decreases the maximum bow height but the final springback angle increases. It is also shown that reasonable model accuracy can be achieved by including the residual stress information due to temper rolling as initial condition in the numerical modeling of a roll forming process.

  20. Computational Analysis of Ares I Roll Control System Jet Interaction Effects on Rolling Moment

    NASA Technical Reports Server (NTRS)

    Deere, Karen A.; Pao, S. Paul; Abdol-Hamid, Khaled S.

    2011-01-01

    The computational flow solver USM3D was used to investigate the jet interaction effects from the roll control system on the rolling moment of the Ares I full protuberance configuration at wind tunnel Reynolds numbers. Solutions were computed at freestream Mach numbers from M = 0.5 to M = 5 at the angle of attack 0deg, at the angle of attack 3.5deg for a roll angle of 120deg, and at the angle of attack 7deg for roll angles of 120deg and 210deg. Results indicate that the RoCS housing provided a beneficial jet interaction effect on vehicle rolling moment for M > or = 0.9. Most of the components downstream of the roll control system housing contributed to jet interaction penalties on vehicle rolling moment.

  1. Optimization Of Rolling Schedule Assuring Desired Final Grain Size Using Control Theory

    NASA Astrophysics Data System (ADS)

    Svyetlichnyy, Dmytro S.

    2004-06-01

    A method of optimal control of the thermomechanical parameters during hot strip rolling processes, based on the modern optimal control theory, is presented in the paper. Optimal parameters are defined from the desired final grain size. The austenite grain size is the criterion of optimization. A state-space model with physical constraints is described. The model is based on the models of rolling process, recrystallization and grain growth, developed for 304L steel. The optimal discrete trajectories for such control parameters as the initial temperature, reductions and interpass time, are to be found. The rolling constrains are applied to the control trajectories (reduction, interpass time) and to state-space trajectories (temperature, rolling force and moment). The results of calculations allow for the design of the optimal rolling schedule.

  2. Effects of the microstructure of twin roll cast and hot rolled plates on the surface quality of presensitized plates

    NASA Astrophysics Data System (ADS)

    Zhu, Yuan-Zhi; Zhang, Ya-Feng; Zhao, Chao-Qi; Zhou, Feng

    2014-09-01

    The effect of the microstructure of plates fabricated both in the traditional process, involving casting, hot rolling and cold rolling (HR), and in the novel twin roll casting + cold rolling (TRC) process on the surface quality of presensitized (PS) plates was analyzed by optical microscopy (OM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDXS). The formation of pores on the surface of the electrolyzed HR plate could be attributed to the presence of approximately 1-μm-sized large Al-Fe precipitates in the HR plate compared to the smaller precipitates in the TRC plate. Moreover, residual graphite lubricants used during the TRC process were entrapped on the surface of the TRC plate during the subsequent rolling process. The entrapped pollutants tended to further deteriorate the formation of pores on the surface of the TRC plate, and no residual carbon was detected on the surface of the HR plate. Furthermore, the surface quality of the TRC plate can be improved by surface cleaning before the cold rolling process, which could dramatically lower the residual graphite on the surface.

  3. The Rolling Friction of Several Airplane Wheels and Tires and the Effect of Rolling Friction on Take-Off

    NASA Technical Reports Server (NTRS)

    Wetmore, J W

    1937-01-01

    This report presents the results of test made to determine the rolling friction of airplane wheels and tires under various conditions of wheel loading, tire inflation pressure, and ground surface. The effect of wheel-bearing type was also investigated. Six pairs of wheels and tires were tested including two sizes of each of the types designated as standard (high pressure), low pressure, and extra low pressure. The results of calculations intended to show the effect of variations in rolling friction on take-off are also presented.

  4. Experimental study of the Portevin-Le Chatelier effect in AA 5754 sheets: Influence of the different rolling routes

    NASA Astrophysics Data System (ADS)

    Astarita, Antonello; Liberini, Mariacira; Velotti, Carla; Sinagra, Ciro; Squillace, Antonino

    2016-10-01

    This paper deals with the experimental study of the Portevin-Le Chatelier (PLC) effect in the rolling of AA 5754 ingots. Three different rolling cycles were investigated in order to minimize or avoid the occurrence of the PLC effect during the rolling process. A full experimental campaign including microstructural observations, tensile tests and fractographic observations was carried out on the rolled sheets in order better understand the phenomena occurring during the rolling process. It was found that is not possible to completely avoid the occurrence of the PLC effect, but by increasing the grain size through an heat treatment between two rolling passes and by adopting an higher thickness reduction for each rolling pass it is possible to reduce the occurrence of the PLC phenomenon. Moreover it was observed that the PLC effect happens only along the rolling direction.

  5. The effects of luminance, size, and duration of a visual line on apparent vertical while the head is being inclined in roll.

    PubMed

    Higashiyama, Atsuki; Murakami, Takashi

    2015-02-01

    We determined orientation of a line that is seen to be vertical (i.e., apparent vertical) while the head is inclined with the trunk upright. In this condition, it has been documented that apparent vertical is independent of head orientation (i.e., orientation constancy) or is in a direction opposite to the head inclination (i.e., the Müller effect). In this study, we have focused not only on the effect of head inclination but also on visual parameters of the line that was used to indicate apparent vertical. As the visual parameters, size (5.5° and 22° in visual angle), duration (0.1 s, 3 s, and no time limit), and luminance (0.026, 0.003, and 0.001 cd/m(2) against total darkness) were varied with the head being inclined within ±30°. The main findings were: 1) the Müller effect was at best 2°, but the head inclination was judged to be much larger than it was; 2) the correlation between apparent vertical and the judgmental error of head inclination was significant but was not very high (r = -0.20); 3) the line of short duration or of low luminance facilitated the Müller effect; and 4) the magnitude of the Müller effect was large when the head was inclined to the right rather than to the left. These findings were compared with the predictions from the theory of allowing for apparent head position, the theory of ocular countertorsion, and the sensory-tonic field theory. Many aspects of the results were consistent with the predictions from the sensory-tonic field theory.

  6. Effect of rolling asymmetry on selected properties of grade 2 titanium sheet

    NASA Astrophysics Data System (ADS)

    Wroński, M.; Wierzbanowski, K.; Wróbel, M.; Wroński, S.; Bacroix, B.

    2015-09-01

    Asymmetric rolling can be used in order to modify material properties and to reduce forces and torques applied during deformation. This geometry of deformation is relatively easy to implement on existing industrial rolling mills and it can provide large volumes of a material. The study of microstructure, crystallographic texture and residual stress in asymmetrically rolled titanium (grade 2) is presented in this work. The above characteristics were examined using the EBSD technique and X-ray diffraction. The rolling asymmetry was realized using two identical rolls, driven by independent motors, rotating with different angular velocities. It was found that asymmetric rolling leads to microstructure modification and refinement. At low deformations one observes a process of grain size decrease caused by the asymmetry of rolling process. In contrast, at the medium range of deformations the microstructure refinement consists mainly in subgrain formation and grain fragmentation. Another observation is that for low to intermediate rolling reductions (≤40%) the predominant mechanisms are slip and twinning, while for higher deformation (>40%) the main mechanism is slip. It was found that grain refinement effect, caused by the rolling asymmetry, persists also after recrystallization annealing. And finally, texture homogenization and reduction of residual stress were confirmed for asymmetrically rolled samples.

  7. Effect of roll-compaction and milling conditions on granules and tablet properties.

    PubMed

    Perez-Gandarillas, Lucia; Perez-Gago, Ana; Mazor, Alon; Kleinebudde, Peter; Lecoq, Olivier; Michrafy, Abderrahim

    2016-09-01

    Dry granulation is an agglomeration process used to produce size-enlarged particles (granules), improving the handling properties of powders such as flowability. In this process, powders are compacted using a roll press to produce ribbons, which are milled in granules used further in the tableting process. The granule and tablet properties are influenced by the existence of different designs of the roll compactors, milling systems and the interaction between process parameters and raw material properties. The main objective of this work was to investigate how different roll-compaction conditions and milling process parameters impact on ribbons, granules and tablet properties, highlighting the role of the sealing system (cheek plates and rimmed roll). In this context, two common excipients differing in their mechanical behaviour (MCC and mannitol) are used. The study is based on the analysis of granule size distribution together with the characterization of loss of compactability during die compaction. Results show that the tensile strength of tablets is lower when using granules than when the raw materials are compressed. Moreover, the plastic material (MCC) is more sensitive than the brittle one (mannitol). Regarding the roll-force, it is observed that the higher the roll force, the lower the tensile strength of tablets from granulated material is. These findings are in agreement with the literature. The comparison of sealing systems shows that the rimmed-roll system leads to slightly stronger tablets than the use of cheek plates. In addition, the use of the rimmed-roll system reduces the amount of fines, in particular when high roll force is applied. Overall, it can be concluded that roll-compaction effect is predominant over the milling effect on the production of fines but less significant on the tablet properties. This study points out that the balance between a good flowability by reducing the amount of fines and appropriate tablet strength is achieved with

  8. Particle size-segregation and roll waves in geophysical mass flows

    NASA Astrophysics Data System (ADS)

    Viroulet, Sylvain; Edwards, Andrew; Kokelaar, Peter; Gray, Nico

    2014-05-01

    Particle size-segregation in geophysical mass flows can have a profound feedback on their local mobility, leading to the formation of resistive bouldery flow fronts, which spontaneously degenerate into leveed channels [1,2] that constrain the flow and enhance run-out. By including particle segregation [3], a composition dependent frictional coupling can be incorporated into depth-averaged geophysical mass flow models to capture both levee formation and flow fingering [4]. However, the channel wavelengths are crucially dependent on the underlying rheology of the flow, which is a second order effect that is still not fully understood. In this paper we analyze a simpler, but closely related, mono-disperse flow in which the granular rheology plays a crucial part in the formation, growth and coarsening of roll waves. Two regimes have been found experimentally:- (i) a classical continuous roll wave regime, and (ii) a novel discrete roll wave regime where the troughs between the wave peaks become completely stationary. This latter behaviour has been observed in debris flows in Fully, Switzerland, and the Jiangjia Gully, China. Grain-size segregation and levee formation in geophysical mass flows, Johnson, C.G., Kokelaar, B.P., Iverson, R.M., Logan, M., LaHusen, R.G. & Gray, J.M.N.T. (2012) J. Geophys. Res. 117, F01032. Fine-grained linings of leveed channels facilitate runout of granular flows, Kokelaar, B.P., Graham, R.L., Gray, J.M.N.T. & Vallance, J.W. (2014) Earth Planet. Sci. Lett. 385, 172-180. Large particle segregation, transport and accumulation in granular free-surface flows. Gray, J.M.N.T. & Kokelaar, B.P. (2010) J. Fluid Mech. 652, 105-137. Segregation-induced fingering instabilities in granular free surface flows, Woodhouse, M.J., Thornton, A.R., Johnson, C.G., Kokelaar, B.P. & Gray, J.M.N.T. (2012) J. Fluid Mech. 709, 543-580.

  9. Effect of Asymmetrical Stand Stiffness on Hot Rolled Strip Shape

    NASA Astrophysics Data System (ADS)

    Gong, Dianyao; Xu, Jianzhong; Jiang, Zhengyi; Zhang, Xiaoming; Liu, Xianghua; Wang, Guodong

    The difference of elastic springs between the operating side (OS) and driving side (DS) of rolling mill has a significant influence on the strip shape not just the strip thickness. Based on the slit beam and roll deformation theories, the roll force distribution was analysed considering the asymmetric stiffness of the OS and DS of rolling mill, and the work roll and backup roll deformation equations were deduced respectively, and the thickness distribution in lateral direction of the hot rolled strip at exit was discussed. Using the roll elastic deformation analysis software which was developed previously based on the influence coefficient method, the roll flattening distribution, roll pressure distribution and the rolling force distribution caused by the asymmetric stand stiffness were calculated and analysed, and the exit strip profile of the rolling mill was also presented. The relationship between the mill stiffness difference and the strip wedge shape or single wave was obtained. Effect of the upstream asymmetric mill on strip crown and flatness of the downstream stands was discussed.

  10. Effects of microalloying on hot-rolled and cold-rolled Q&P steels

    NASA Astrophysics Data System (ADS)

    Azevedo de Araujo, Ana Luiza

    austenite morphology from lath-like to blocky with increasing CT was observed. Hardness generally increased with decreasing CT, consistent with the increased fraction of harder phases in the microstructure. For the cold-rolled Q&P study, several combinations of quenching temperature (QT), partitioning temperature (PT), and partitioning time (t p) were examined using heat treatments in salt baths. Uniaxial tensile tests and RA measurements via x-ray diffraction (XRD) were performed for all alloys and heat treatment conditions. Scanning electron microscope (SEM) imaging and EBSD were conducted for a few select conditions. In terms of microstructure, Nb promoted an extensive refinement of the prior austenite grain size. Additions of V and Nb also seemed to affect the morphology of the microstructural constituents. It was observed that V generally increased austenite fractions at lower t p's, and the Nb-containing alloys had greater austenite fractions in most instances when compared to the Base alloy. Carbon content in austenite was usually increased or maintained with additions of Nb and V. In terms of mechanical properties, V slightly improved strength and elongation when compared to the Base alloy for most conditions. Niobium additions were somewhat more effective in improving ductility.

  11. Helicopter roll control effectiveness criteria program summary

    NASA Technical Reports Server (NTRS)

    Heffley, Robert K.; Bourne, Simon M.; Mnich, Marc A.

    1988-01-01

    A study of helicopter roll control effectiveness is summarized for the purpose of defining military helicopter handling qualities requirements. The study is based on an analysis of pilot-in-the-loop task performance of several basic maneuvers. This is extended by a series of piloted simulations using the NASA Ames Vertical Motion Simulator and selected flight data. The main results cover roll control power and short-term response characteristics. In general the handling qualities requirements recommended are set in conjunction with desired levels of flight task and maneuver response which can be directly observed in actual flight. An important aspect of this, however, is that vehicle handling qualities need to be set with regard to some quantitative aspect of mission performance. Specific examples of how this can be accomplished include a lateral unmask/remask maneuver in the presence of a threat and an air tracking maneuver which recognizes the kill probability enhancement connected with decreasing the range to the target. Conclusions and recommendations address not only the handling qualities recommendations, but also the general use of flight simulators and the dependence of mission performance on handling qualities.

  12. Effects of False Tilt Cues on the Training of Manual Roll Control Skills

    NASA Technical Reports Server (NTRS)

    Zaal, Peter M. T.; Popovici, Alexandru; Zavala, Melinda A.

    2015-01-01

    This paper describes a transfer-of-training study performed in the NASA Ames Vertica lMotion Simulator. The purpose of the study was to investigate the effect of false tilt cues on training and transfer of training of manual roll control skills. Of specific interest were the skills needed to control unstable roll dynamics of a mid-size transport aircraft close to the stall point. Nineteen general aviation pilots trained on a roll control task with one of three motion conditions: no motion, roll motion only, or reduced coordinated roll motion. All pilots transferred to full coordinated roll motion in the transfer session. A novel multimodal pilot model identification technique was successfully applied to characterize how pilots' use of visual and motion cues changed over the course of training and after transfer. Pilots who trained with uncoordinated roll motion had significantly higher performance during training and after transfer, even though they experienced the false tilt cues. Furthermore, pilot control behavior significantly changed during the two sessions, as indicated by increasing visual and motion gains, and decreasing lead time constants. Pilots training without motion showed higher learning rates after transfer to the full coordinated roll motion case.

  13. Modeling recrystallization kinetics, grain sizes, and textures during multipass hot rolling

    NASA Astrophysics Data System (ADS)

    Vatne, Hans Erik; Ørsund, Roar; Marthinsen, Knut; Nes, Erik

    1996-12-01

    A physically based model for the evolution of recrystallization microstructures and textures during hot rolling of aluminum is presented. The approach taken differs from similar models developed for steels. The present model is based on recent experimental investigations directed toward identifying the nature of the nucleation sites for recrystallized grains of different crystallographic orientations. Particle stimulated nucleation (PSN) and nucleation from cube bands and grain boundary regions have been incorporated in the model. The multipass aspect complicates the modeling due to partial recrystallization between the rolling passes. Two different approaches have been suggested to handle this. The model has been applied to predictions of recrystallization kinetics, recrystallized grain sizes, and recrystallization textures during multipass hot rolling of aluminum. The predictions are reasonable compared to experimental results.

  14. Effects of hot rolled microstructure after twin-roll casting on microstructure, texture and magnetic properties of low silicon non-oriented electrical steel

    NASA Astrophysics Data System (ADS)

    Liu, Hai-Tao; Wang, Yin-Ping; An, Ling-Zi; Wang, Zhao-Jie; Hou, Dao-Yuan; Chen, Jun-Mou; Wang, Guo-Dong

    2016-12-01

    In this work, a 0.71 wt%Si+0.44 wt%Al as-cast strip was produced by novel twin-roll casting. Some as-cast samples were respectively reheated and hot rolled at different temperatures in order to obtain different microstructure prior to cold rolling and annealing. The effects of the hot rolled microstructure on microstructure, texture evolution and magnetic properties were investigated in detail. A coarse deformed microstructure with λ-fiber texture was formed after hot rolling at 850-1050 °C, finally leading to an inhomogeneous recrystallization microstructure with strong λ-fiber, Goss and extremely weak γ-fiber texture. By contrast, a fine transformed microstructure was formed after hot rolling at 1150-1250 °C, finally leading to a fine and homogeneous recrystallization microstructure with stronger α-fiber, γ-fiber and much weaker λ-fiber texture. It should be noted that both the magnetic induction and core loss non-monotonically decreased or increased according to the hot rolling temperature. The unfavorable α-fiber and γ-fiber textures in the annealed sheets were much weaker than those of the conventional products regardless of the hot rolling temperature, thus contributing to a much higher magnetic induction. However, the average grain size in the annealed sheets was much lower than those of the conventional products regardless of the hot rolling temperature, thus leading to a higher core loss except the case of 1050 °C. Hence, it is underscored that better integrated magnetic properties than those of the conventional products can be obtained by optimizing the hot rolled microstructure to produce final desirable recrystallization microstructure and texture.

  15. Analysis of the effects of wing interference on the tail contributions to the rolling derivatives

    NASA Technical Reports Server (NTRS)

    Michael, William H , Jr

    1952-01-01

    An analysis of the effects of wing interference on the tail contributions to the rolling stability derivatives of complete airplane configurations is made by calculating the angularity of the air stream at the vertical tail due to rolling and determining the resulting forces and moments. Some of the important factors which affect the resultant angularity on the vertical tail are wing aspect ratio and sweepback, vertical-tail span, and considerations associated with angle of attack and airplane geometry. Some calculated sidewash results for a limited range of plan forms and vertical-tail sizes are presented. Equations taking into account the sidewash results are given for determining the tail contributions to the rolling derivatives. Comparisons of estimated and experimental results indicate that a consideration of wing interference effects improves the estimated values of the tail contributions to the rolling derivatives and that fair agreement with available experimental data is obtained.

  16. Effective parameters in ground roll attenuation using FO CRS stacking

    NASA Astrophysics Data System (ADS)

    Rastegar, Seyyed Ali Fa'al; Javaherian, Abdolrahim; Farajkhah, Naser Keshavarz; Monfared, Mehrdad Soleimani; Zarei, Abbas

    2016-12-01

    Ground roll is a coherent noise in land seismic data that has high energy, high amplitude, low frequency and low velocity. It has to be attenuated in the seismic data processing as it may mask reflections in the zone of ground roll. In this study, we employed common reflection surface for finite offset (FO CRS) to attenuate the ground roll. The FO CRS stacking operator is a hyperbola; therefore, it fits the hyperbolic reflections in the prestack data. Conversely, the ground roll is linear in the common-midpoint (CMP) and common-shot (CS) gathers and can be distinguished and attenuated by the FO CRS operator. Thus, we search for the dip and curvature of the reflections in the CMP section and CS gather prior to the finite-offset section. When the algorithm is specified, the ground roll and reflections have low and high coherency values, respectively. So, any event with non-hyperbolic traveltime, like the linear traveltime ground roll can be removed. We applied the proposed method on a synthetic and an oilfield data from the west of Iran. Results showed that the FO CRS stacking method properly attenuated the ground roll. Further investigations were the effects of spatial aliasing, frequency content, random noise, ground roll dip, the range of dip and curvature scans and reflection amplitudes on ground roll attenuation by the FO CRS stacking. From mentioned parameters, spatial aliasing, frequency content, and random noise had no significant effects. On the contrary, the proposed method turned out to be strongly dependent upon ground roll dip, the range of dip and curvature scans and reflection amplitudes.

  17. Dynamic Effect of Rolling Massage on Blood Flow

    NASA Astrophysics Data System (ADS)

    Chen, Yan-Yan; Yi, Hou-Hui; Li, Hua-Bing; Fang, Hai-Ping

    2009-02-01

    The Chinese traditional medical massage has been used as a natural therapy to eliminate some diseases. Here, the effect of the rolling massage frequency to the blood flow in the blood vessels under the rolling massage manipulation is studied by the lattice Boltzmann simulation. The simulation results show that when the frequency is smaller than or comparable to the pulsatile frequency of the blood flow, the effect on the blood flux by the rolling massage is small. On the contrast, if the frequency is twice or more times of the pulsatile frequency of the blood flow, the blood flux is greatly enhanced and increases linearly with respect to the frequency. Similar behavior has also been observed on the shear stress on the blood vessel walls. The result is helpful for understanding that the rolling massage has the function of promoting the blood circulation and removing the blood stasis.

  18. Effect of Rolling Massage on the Vortex Flow in Blood Vessels with Lattice Boltzmann Simulation

    NASA Astrophysics Data System (ADS)

    Yi, Hou Hui

    The rolling massage manipulation is a classic Chinese Medical Massage, which is a nature therapy in eliminating many diseases. Here, the effect of the rolling massage on the cavity flows in blood vessel under the rolling manipulation is studied by the lattice Boltzmann simulation. The simulation results show that the vortex flows are fully disturbed by the rolling massage. The flow behavior depends on the rolling velocity and the rolling depth. Rolling massage has a better effect on the flows in the cavity than that of the flows in a planar blood vessel. The result is helpful to understand the mechanism of the massage and develop the rolling techniques.

  19. On Effect Size

    ERIC Educational Resources Information Center

    Kelley, Ken; Preacher, Kristopher J.

    2012-01-01

    The call for researchers to report and interpret effect sizes and their corresponding confidence intervals has never been stronger. However, there is confusion in the literature on the definition of effect size, and consequently the term is used inconsistently. We propose a definition for effect size, discuss 3 facets of effect size (dimension,…

  20. On Effect Size

    ERIC Educational Resources Information Center

    Kelley, Ken; Preacher, Kristopher J.

    2012-01-01

    The call for researchers to report and interpret effect sizes and their corresponding confidence intervals has never been stronger. However, there is confusion in the literature on the definition of effect size, and consequently the term is used inconsistently. We propose a definition for effect size, discuss 3 facets of effect size (dimension,…

  1. A defect size estimation method based on operational speed and path of rolling elements in defective bearings

    NASA Astrophysics Data System (ADS)

    Moazen-ahmadi, Alireza; Howard, Carl Q.

    2016-12-01

    This paper describes the effect of inertia and centrifugal force that act on a rotating rolling element in a defective bearing, on the measured vibration signature. These effects are more pronounced as the speed of components increases. Significant speed-dependency of the characteristic events that are generated at the angular extents of the defect are shown by simulation and experimental measurements. The sources of inaccuracy and the speed-dependency in the existing defect size estimation algorithms are explained. The analyses presented in this study are essential to develop accurate and reliable defect size estimation algorithms. A complete defect size estimation algorithm is proposed that is more accurate and less biased by shaft speed when compared with existing methods.

  2. MCC-mannitol mixtures after roll compaction/dry granulation: percolation thresholds for ribbon microhardness and granule size distribution.

    PubMed

    Pérez Gago, Ana; Kleinebudde, Peter

    2016-04-07

    In roll compaction, the specific compaction force, the gap width and the roll speed are the most important settings as they have a high impact in the products obtained. However the mechanical properties of the mixture being compacted are also critical. For this reason, a multilevel full factorial design including these parameters as factors plus three repetitions of the center point was performed for microcrystalline cellulose, mannitol and five binary mixtures (15, 30, 50, 70 and 85% MCC). These two reference excipients were chosen in order to investigate the plastic/brittle behavior of mixtures for the roll compaction process. These materials were roll compacted in a 3-W-Polygran(®) 250/50/3 (Gerteis) and the ribbons obtained were collected and milled into granules which were characterized regarding granule size distribution. After statistical evaluation, it was found that the most critical factors affecting the D10, D50, D90 and the fines fraction from the granules were the gap width and the specific compaction force, as well as the proportion of MCC together with its quadratic effect and the interaction between force and proportion of MCC. The microhardness of the ribbons from the center point as well as the D10, D50, D90 and the fines fraction from the granules produced at these same conditions were characterized. In all the cases, the proportion of MCC, i.e. the composition of the mixture, showed also an important effect on these properties measured. In this sense, the percolation theory was applied in order to study further the importance of the plastic/brittle ratio by calculating the percolation threshold or the limit over which the behavior of the system changes. This resulted in values of 34% for the HU (expression of microhardness), 27% and 28% for the D10 and fines, respectively (percolation of MCC) and 84% and 85% for the D50 and D90, respectively (percolation of mannitol).

  3. On effect size.

    PubMed

    Kelley, Ken; Preacher, Kristopher J

    2012-06-01

    The call for researchers to report and interpret effect sizes and their corresponding confidence intervals has never been stronger. However, there is confusion in the literature on the definition of effect size, and consequently the term is used inconsistently. We propose a definition for effect size, discuss 3 facets of effect size (dimension, measure/index, and value), outline 10 corollaries that follow from our definition, and review ideal qualities of effect sizes. Our definition of effect size is general and subsumes many existing definitions of effect size. We define effect size as a quantitative reflection of the magnitude of some phenomenon that is used for the purpose of addressing a question of interest. Our definition of effect size is purposely more inclusive than the way many have defined and conceptualized effect size, and it is unique with regard to linking effect size to a question of interest. Additionally, we review some important developments in the effect size literature and discuss the importance of accompanying an effect size with an interval estimate that acknowledges the uncertainty with which the population value of the effect size has been estimated. We hope that this article will facilitate discussion and improve the practice of reporting and interpreting effect sizes. (c) 2012 APA, all rights reserved)

  4. Effects of homogenization treatment on recrystallization behavior of 7150 aluminum sheet during post-rolling annealing

    SciTech Connect

    Guo, Zhanying; Zhao, Gang; Chen, X.-Grant

    2016-04-15

    The effects of two homogenization treatments applied to the direct chill (DC) cast billet on the recrystallization behavior in 7150 aluminum alloy during post-rolling annealing have been investigated using the electron backscatter diffraction (EBSD) technique. Following hot and cold rolling to the sheet, measured orientation maps, the recrystallization fraction and grain size, the misorientation angle and the subgrain size were used to characterize the recovery and recrystallization processes at different annealing temperatures. The results were compared between the conventional one-step homogenization and the new two-step homogenization, with the first step being pretreated at 250 °C. Al{sub 3}Zr dispersoids with higher densities and smaller sizes were obtained after the two-step homogenization, which strongly retarded subgrain/grain boundary mobility and inhibited recrystallization. Compared with the conventional one-step homogenized samples, a significantly lower recrystallized fraction and a smaller recrystallized grain size were obtained under all annealing conditions after cold rolling in the two-step homogenized samples. - Highlights: • Effects of two homogenization treatments on recrystallization in 7150 Al sheets • Quantitative study on the recrystallization evolution during post-rolling annealing • Al{sub 3}Zr dispersoids with higher densities and smaller sizes after two-step treatment • Higher recrystallization resistance of 7150 sheets with two-step homogenization.

  5. The effect of caster types on global rolling resistance in manual wheelchairs on indoor and outdoor surfaces.

    PubMed

    Chan, Franco H N; Eshraghi, Mehdi; Alhazmi, Mohammad A; Sawatzky, Bonita J

    2017-06-07

    An important aspect of reducing the strain of wheeling is to decrease rolling resistance. Previous laboratory research, using a treadmill, determined that smaller casters significantly increased rolling resistance. The purpose of this study was to determine the effect of caster size on various indoor and outdoor surfaces on global wheelchair rolling resistance. Three caster types with sizes 4 in, 5 in, and 6 in, three indoor surfaces, and three outdoor surfaces were studied. A manual wheelchair was passively pulled along each surface at 1.11 m/s (3.64 ft/s) by a power wheelchair, and the global rolling resistance of the manual wheelchair was measured using a calibrated force transducer. A 3×3 repeated measures analysis of variance (ANOVA) was conducted for both indoor and outdoor environments. The 4-in casters resulted in the highest global rolling resistance on most surfaces. The 5-in casters had the least rolling resistance on most indoor surfaces, and the 6-in casters had the least rolling resistance on most outdoor surfaces. Although 4-in casters are more popular among active wheelchair users, larger casters were shown to have lower rolling resistance on most surfaces. This study may help users select the best caster size depending upon their daily activities and lifestyle.

  6. Effect of biomimetic coupling units' morphologies on rolling contact fatigue wear resistance of steel from machine tool rolling tracks

    NASA Astrophysics Data System (ADS)

    Yang, Wanshi; Zhou, Hong; Sun, Liang; Wang, Chuanwei; Chen, Zhikai

    2014-04-01

    The rolling contact fatigue wear resistance plays an important role on ensuring machining precision of machine tool using rolling tracks. Bio-inspired wearable surfaces with the alternated hardness were prepared on the specimen of steel material from machine tool rolling tracks by biomimetic coupling laser remelting method to imitate biological coupling principle. The microstructures and micromorphologies of bionic units in different sizes were characterized by optical microscope. The specimens with bionic units in different sizes and distributions were tested for rolling contact fatigue wear resistance. Combining the finite element analysis and the results of wear tests, a discussion on rolling contact fatigue wear was had. The specimens with bionic units had better rolling contact fatigue wear resistance than the untreated one, while the specimens with bionic units in the alternative depth's distributions present a better rolling contact fatigue wear resistance than the ones with bionic units in the single depth's distribution. It attributed to the alternative distribution made further improvement on the dispersion of depth of stress concentration.

  7. Quantum slow-roll and quantum fast-roll inflationary initial conditions: CMB quadrupole suppression and further effects on the low CMB multipoles

    SciTech Connect

    Cao, F. J.; Vega, H. J. de; Sanchez, N. G.

    2008-10-15

    Quantum fast-roll initial conditions for the inflaton which are different from the classical fast-roll conditions and from the quantum slow-roll conditions can lead to inflation that lasts long enough. These quantum fast-roll initial conditions for the inflaton allow for kinetic energies of the same order of the potential energies and nonperturbative inflaton modes with nonzero wave numbers. Their evolution starts with a transitory epoch where the redshift due to the expansion succeeds to assemble the quantum excited modes of the inflaton in a homogeneous (zero mode) condensate, and the large value of the Hubble parameter succeeds to overdamp the fast roll of the redshifted inflaton modes. After this transitory stage the effective classical slow-roll epoch is reached. Most of the e-folds are produced during the slow-roll epoch, and we recover the classical slow-roll results for the scalar and tensor metric perturbations plus corrections. These corrections are important if scales which are horizon size today exited the horizon by the end of the transitory stage and, as a consequence, the lower cosmic microwave background (CMB) multipoles get suppressed or enhanced. Both for scalar and tensor metric perturbations, fast roll leads to a suppression of the amplitude of the perturbations (and of the low CMB multipoles), while the quantum precondensate epoch gives an enhancement of the amplitude of the perturbations (and of the low CMB multipoles). These two types of corrections can compete and combine in a scale dependent manner. They turn out to be smaller in new inflation than in chaotic inflation. These corrections arise as natural consequences of the quantum nonperturbative inflaton dynamics, and can allow a further improvement of the fitting of inflation plus the {lambda}CMB model to the observed CMB spectra. In addition, the corrections to the tensor metric perturbations will provide an independent test of this model. Thus, the effects of quantum inflaton fast-roll

  8. Site of nutrient digestion by dairy cows fed corn of different particle sizes or steam-rolled.

    PubMed

    Callison, S L; Firkins, J L; Eastridge, M L; Hull, B L

    2001-06-01

    Five primiparous Holstein cows were cannulated in the rumen, duodenum, and ileum and were fed diets containing 50% alfalfa silage and 36.6% coarse-, medium-, or fine-ground corn (CGC, MGC, and FGC, respectively, with mean particle sizes of 4.8, 2.6, or 1.2 mm), steam-rolled corn (SRC; density of 0.53 kg/L), or a 50:50 mix of CGC and SRC (SC) to evaluate how corn processing affects site of digestibility of nonstructural carbohydrates (NSC) and neutral detergent fiber (NDF). Decreasing the particle size of corn quadratically affected true ruminal digestibility of NSC (49.8, 46.5, and 87.0%, respectively). Because of compensatory digestion postruminally, a smaller increase (from 91.3 to 98.0%) in total tract digestibility of NSC was noted as particle size decreased. A small but significant linear shift in NDF digestion from the rumen to the large intestine was detected as corn particle size decreased. The addition of SRC to CGC linearly increased true NSC digestibility in the rumen about 20 percentage units but had much smaller effects on total tract digestibility. Despite the large impact of corn processing on NSC digestibility in the rumen, flow of bacterial N to the rumen was not affected by treatment. Reducing the particle size of corn decreased the apparent escape of corn protein, but steam-rolling had no effect. Corn should be finely ground to maximize total tract OM digestibility or steam-processed to densities less than 0.53 kg/L for maximal starch digestibility. However, fine-grinding or steam-processing of corn may have only a modest impact on total tract OM digestibility.

  9. The Effect of Rolling As-Cast and Homogenized U-10Mo Samples on the Microstructure Development and Recovery Curves

    SciTech Connect

    Joshi, Vineet V.; Paxton, Dean M.; Lavender, Curt A.; Burkes, Douglas

    2016-07-30

    Over the past several years Pacific Northwest National Laboratory (PNNL) has been actively involved in supporting the U.S. Department of Energy National Nuclear Security Administration Office of Material Management and Minimization (formerly Global Threat Reduction Initiative). The U.S. High- Power Research Reactor (USHPRR) project is developing alternatives to existing highly enriched uranium alloy fuel to reduce the proliferation threat. One option for a high-density metal fuel is uranium alloyed with 10 wt% molybdenum (U-10Mo). Forming the U-10Mo fuel plates/foils via rolling is an effective technique and is actively being pursued as part of the baseline manufacturing process. The processing of these fuel plates requires systematic investigation/understanding of the pre- and post-rolling microstructure, end-state mechanical properties, residual stresses, and defects, their effect on the mill during processing, and eventually, their in-reactor performance. In the work documented herein, studies were conducted to determine the effect of cold and hot rolling the as-cast and homogenized U-10Mo on its microstructure and hardness. The samples were homogenized at 900°C for 48 h, then later annealed for several durations and temperatures to investigate the effect on the material’s microstructure and hardness. The rolling of the as-cast plate, both hot and cold, was observed to form a molybdenum-rich and -lean banded structure. The cold rolling was ineffective, and in some cases exacerbated the as-cast defects. The grains elongated along the rolling direction and formed a pancake shape, while the carbides fractured perpendicularly to the rolling direction and left porosity between fractured particles of UC. The subsequent annealing of these samples at sub-eutectoid temperatures led to rapid precipitation of the ' lamellar phase, mainly in the molybdenum-lean regions. Annealing the samples above the eutectoid temperature did not refine the grain size or the banded

  10. Roll Forming of AHSS: Numerical Simulation and Investigation of Effects of Main Process Parameters on Quality

    NASA Astrophysics Data System (ADS)

    Salonitis, Konstantinos; Paralikas, John; Chryssolouris, George

    The roll forming process is one of the main processes of producing straight profiles in many industrial sectors. The introduction of Advanced High Strength Steels (AHSS), such as the DP and TRIP-series, into the production of roll-formed profiles has emerged new challenges. The combination of a higher yield strength with a lower total elongation of AHSS, brings new challenges to the roll forming process. In the current study, the numerical simulation of a V-section profile has been implemented. The effect of the main process parameters, such as the roll forming line velocity, rolls inter-distance, roll gap and rolls diameter on quality characteristics is investigated.

  11. The effects of cold rolling and heat treatment on Al 6063 reinforced with silicon carbide granules

    NASA Astrophysics Data System (ADS)

    Balogun, S. A.; Adeosun, S. O.; Sanni, O. S.

    2009-08-01

    The effects of cold rolling and heat treatment on the strength and ductility of aluminum alloy 6063 reinforced with silicon carbide granules have been examined. Silicon carbide (SiCp) 100 μm grain size was added to 6063 aluminum in volume fractions of 0-30% to produce samples for heat treatment and cold rolling. The results show that an optimum combination of strength and ductility at 137.92 MPa and true strain of 0.173 is achievable with rolled-and-tempered samples containing 10% SiCp. This is a significant improvement on 6063 aluminum alloy having an ultimate tensile strength of ˜100 MPa at true strain of 0.18.

  12. Effects of surface removal on rolling-element fatigue

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.

    1987-01-01

    The Lundberg-Palmgren equation was modified to show the effect on rolling-element fatigue life of removing by grinding a portion of the stressed volume of the raceways of a rolling-element bearing. Results of this analysis show that depending on the amount of material removed, and depending on the initial running time of the bearing when material removal occurs, the 10-percent life of the reground bearings ranges from 74 to 100 percent of the 10-percent life of a brand new bearing. Three bearing types were selected for testing. A total of 250 bearings were reground. Of this matter, 30 bearings from each type were endurance tested to 1600 hr. No bearing failure occurred related to material removal. Two bearing failures occurred due to defective rolling elements and were typical of those which may occur in new bearings.

  13. Effect of rolling on dissipation in fault gouges

    SciTech Connect

    Alonso-Marroquin, F.; Vardoulakis, I.; Herrmann, H. J.; Weatherley, D.; Mora, P.

    2006-09-15

    Sliding and rolling are two outstanding deformation modes in granular media. The first one induces frictional dissipation whereas the latter one involves deformation with negligible resistance. Using numerical simulations on two-dimensional shear cells, we investigate the effect of the grain rotation on the energy dissipation and the strength of granular materials under quasistatic shear deformation. Rolling and sliding are quantified in terms of the so-called Cosserat rotations. The observed spontaneous formation of vorticity cells and clusters of rotating bearings may provide an explanation for the long standing heat flow paradox of earthquake dynamics.

  14. Effect of rolling on dissipation in fault gouges.

    PubMed

    Alonso-Marroquín, F; Vardoulakis, I; Herrmann, H J; Weatherley, D; Mora, P

    2006-09-01

    Sliding and rolling are two outstanding deformation modes in granular media. The first one induces frictional dissipation whereas the latter one involves deformation with negligible resistance. Using numerical simulations on two-dimensional shear cells, we investigate the effect of the grain rotation on the energy dissipation and the strength of granular materials under quasistatic shear deformation. Rolling and sliding are quantified in terms of the so-called Cosserat rotations. The observed spontaneous formation of vorticity cells and clusters of rotating bearings may provide an explanation for the long standing heat flow paradox of earthquake dynamics.

  15. A Flight Investigation of the Damping in Roll and Rolling Effectiveness Including Aeroelastic Effects of Rocket Propelled Missile Models Having Cruciform, Triangular, Interdigitated Wings and Tails

    NASA Technical Reports Server (NTRS)

    Hopko, R. N.

    1951-01-01

    The damping in roll and rolling effectiveness of two models of a missile having cruciform, triangular, interdigitated wings and tails have been determined through a Mach number range of 0.8 to 1.8 by utilizing rocket-propelled test vehicles. Results indicate that the damping in roll was relatively constant over the Mach umber range investigated. The rolling effectiveness was essentially constant at low supersonic speeds and increased with increasing mach numbers in excess of 1.4 over the Mach number range investigated. Aeroelastic effects increase the rolling-effectiveness parameters pb/2V divided by delta and decrease both the rolling-moment coefficient due to wing deflection and the damping-in-roll coefficient.

  16. Efficiency roll-off suppression in organic light-emitting diodes using size-tunable bimetallic bowtie nanoantennas at high current densities

    NASA Astrophysics Data System (ADS)

    Zhao, Yukun; Yun, Feng; Huang, Yi; Wu, Zhaoxin; Li, Yufeng; Jiao, Bo; Feng, Lungang; Li, Sanfeng; Ding, Wen; Zhang, Ye

    2016-07-01

    Size-tunable bimetallic bowtie nanoantennas have been utilized to suppress the efficiency roll-off characteristics in organic light-emitting diodes (OLEDs) using both the numerical and experimental approaches. The resonant range can be widened by the strong dual-atomic couplings in bimetallic bowtie nanoantennas. Compared with the green OLED with conventional bowtie nanoantennas at a high current density of 800 mA/cm2, the measured efficiency roll-off ratio of the OLED with size-modulated bowtie nanoantennas is decreased from 53.2% to 41.8%, and the measured current efficiency is enhanced by 29.9%. When the size-modulated bowtie nanoantennas are utilized in blue phosphorescent OLEDs, the experimental roll-off ratio is suppressed from 43.6% to 25.9% at 250 mA/cm2, and the measured current efficiency is also enhanced significantly. It is proposed that the efficiency roll-off suppression is mainly related to the enhanced localized surface plasmon effect, which leads to a shorter radiative lifetime.

  17. Efficiency roll-off suppression in organic light-emitting diodes using size-tunable bimetallic bowtie nanoantennas at high current densities

    SciTech Connect

    Zhao, Yukun; Yun, Feng Li, Yufeng; Feng, Lungang; Ding, Wen; Huang, Yi; Wu, Zhaoxin; Jiao, Bo; Li, Sanfeng; Zhang, Ye

    2016-07-04

    Size-tunable bimetallic bowtie nanoantennas have been utilized to suppress the efficiency roll-off characteristics in organic light-emitting diodes (OLEDs) using both the numerical and experimental approaches. The resonant range can be widened by the strong dual-atomic couplings in bimetallic bowtie nanoantennas. Compared with the green OLED with conventional bowtie nanoantennas at a high current density of 800 mA/cm{sup 2}, the measured efficiency roll-off ratio of the OLED with size-modulated bowtie nanoantennas is decreased from 53.2% to 41.8%, and the measured current efficiency is enhanced by 29.9%. When the size-modulated bowtie nanoantennas are utilized in blue phosphorescent OLEDs, the experimental roll-off ratio is suppressed from 43.6% to 25.9% at 250 mA/cm{sup 2}, and the measured current efficiency is also enhanced significantly. It is proposed that the efficiency roll-off suppression is mainly related to the enhanced localized surface plasmon effect, which leads to a shorter radiative lifetime.

  18. Effect of deformation path on microstructure, microhardness and texture evolution of interstitial free steel fabricated by differential speed rolling

    SciTech Connect

    Hamad, Kotiba; Chung, Bong Kwon; Ko, Young Gun

    2014-08-15

    This paper reports the effect of the deformation path on the microstructure, microhardness, and texture evolution of interstitial free (IF) steel processed by differential speed rolling (DSR) method. For this purpose, total height reductions of 50% and 75% were imposed on the samples by a series of differential speed rolling operations with various height reductions per pass (deformation levels) ranging from 10 to 50% under a fixed roll speed ratio of 1:4 for the upper and lower rolls, respectively. Microstructural observations using transmission electron microscopy and electron backscattered diffraction measurements showed that the samples rolled at deformation level of 50% had the finest mean grain size (∼ 0.5 μm) compared to the other counterparts; also the samples rolled at deformation level of 50% showed a more uniform microstructure. Based on the microhardness measurements along the thickness direction of the deformed samples, gradual evolution of the microhardness value and its homogeneity was observed with the increase of the deformation level per pass. Texture analysis showed that, as the deformation level per pass increased, the fraction of alpha fiber and gamma fiber in the deformed samples increased. The textures obtained by the differential speed rolling process under the lubricated condition would be equivalent to those obtained by the conventional rolling. - Highlights: • Effect of DSR deformation path on microstructure of IF steel is significant. • IF steel rolled at deformation level of 50% has the ultrafine grains of ∼ 0.5 μm. • Rolling texture components are pronounced with increasing deformation level.

  19. EFFECT OF DIFFERENT FOAM ROLLING VOLUMES ON KNEE EXTENSION FATIGUE

    PubMed Central

    Neto, Victor Gonçalves Corrêa

    2016-01-01

    Background Foam rolling (FR) is a common intervention utilized for the purpose of acutely increasing range-of-motion without subsequent decreases in performance. FR is characterized as an active technique which subject performs upon themselves. Thus, it is believed that the accumulated fatigue can influence whether the task can be continued. Purpose To analyze the effect of different foam rolling volumes on fatigue of the knee extensors. Methods Twenty-five recreationally active females (age 27.7 ± 3.56 y, height 168.4 ± 7.1 cm, weight 69.1 ± 10.2 kg) were recruited for the study. The experiment involved three sets of knee extensions with a pre-determined 10 repetition maximum load to concentric failure. Then, subjects performed the control (CONT) and foam rolling (FR) conditions. FR conditions consisted of different anterior thigh rolling volumes (60-, 90-, and 120-seconds) which were performed during the inter-set rest period. After that, the fatigue index was calculated and compared between each experimental condition. Fatigue index indicates how much (%) resistance the subjects experienced, calculated by the equation: (thidset/firstset) x 100. Results Fatigue index was statistically significantly greater (greater fatigue resistance) for CONT compared to FR90 (p = 0.001) and FR120 (p = 0.001). Similarly, higher fatigue resistance was observed for FR60 when compared to FR120 (p = 0.048). There were no significant differences between the other conditions (p > 0.005). Conclusion The finding of foam rolling fatigue index decline (less fatigue resistance) as compared to control conditions may have implications for foam rolling prescription and implementation, in both rehabilitation and athletic populations. For the purposes of maximum repetition performance, foam rolling should not be applied to the agonist muscle group between sets of knee extensions. Moreover, it seems that volumes greater than 90-seconds are detrimental to the

  20. EFFECT OF DIFFERENT FOAM ROLLING VOLUMES ON KNEE EXTENSION FATIGUE.

    PubMed

    Monteiro, Estêvão Rios; Neto, Victor Gonçalves Corrêa

    2016-12-01

    Foam rolling (FR) is a common intervention utilized for the purpose of acutely increasing range-of-motion without subsequent decreases in performance. FR is characterized as an active technique which subject performs upon themselves. Thus, it is believed that the accumulated fatigue can influence whether the task can be continued. To analyze the effect of different foam rolling volumes on fatigue of the knee extensors. Twenty-five recreationally active females (age 27.7 ± 3.56 y, height 168.4 ± 7.1 cm, weight 69.1 ± 10.2 kg) were recruited for the study. The experiment involved three sets of knee extensions with a pre-determined 10 repetition maximum load to concentric failure. Then, subjects performed the control (CONT) and foam rolling (FR) conditions. FR conditions consisted of different anterior thigh rolling volumes (60-, 90-, and 120-seconds) which were performed during the inter-set rest period. After that, the fatigue index was calculated and compared between each experimental condition. Fatigue index indicates how much (%) resistance the subjects experienced, calculated by the equation: (thidset/firstset) x 100. Fatigue index was statistically significantly greater (greater fatigue resistance) for CONT compared to FR90 (p = 0.001) and FR120 (p = 0.001). Similarly, higher fatigue resistance was observed for FR60 when compared to FR120 (p = 0.048). There were no significant differences between the other conditions (p > 0.005). The finding of foam rolling fatigue index decline (less fatigue resistance) as compared to control conditions may have implications for foam rolling prescription and implementation, in both rehabilitation and athletic populations. For the purposes of maximum repetition performance, foam rolling should not be applied to the agonist muscle group between sets of knee extensions. Moreover, it seems that volumes greater than 90-seconds are detrimental to the ability to continually produce force. 2b.

  1. Correlational effect size benchmarks.

    PubMed

    Bosco, Frank A; Aguinis, Herman; Singh, Kulraj; Field, James G; Pierce, Charles A

    2015-03-01

    Effect size information is essential for the scientific enterprise and plays an increasingly central role in the scientific process. We extracted 147,328 correlations and developed a hierarchical taxonomy of variables reported in Journal of Applied Psychology and Personnel Psychology from 1980 to 2010 to produce empirical effect size benchmarks at the omnibus level, for 20 common research domains, and for an even finer grained level of generality. Results indicate that the usual interpretation and classification of effect sizes as small, medium, and large bear almost no resemblance to findings in the field, because distributions of effect sizes exhibit tertile partitions at values approximately one-half to one-third those intuited by Cohen (1988). Our results offer information that can be used for research planning and design purposes, such as producing better informed non-nil hypotheses and estimating statistical power and planning sample size accordingly. We also offer information useful for understanding the relative importance of the effect sizes found in a particular study in relationship to others and which research domains have advanced more or less, given that larger effect sizes indicate a better understanding of a phenomenon. Also, our study offers information about research domains for which the investigation of moderating effects may be more fruitful and provide information that is likely to facilitate the implementation of Bayesian analysis. Finally, our study offers information that practitioners can use to evaluate the relative effectiveness of various types of interventions. PsycINFO Database Record (c) 2015 APA, all rights reserved.

  2. Delamination Effect on Impact Properties of Ultrafine-Grained Low-Carbon Steel Processed by Warm Caliber Rolling

    NASA Astrophysics Data System (ADS)

    Inoue, Tadanobu; Yin, Fuxing; Kimura, Yuuji; Tsuzaki, Kaneaki; Ochiai, Shojiro

    2010-02-01

    Bulk ultrafine-grained (UFG) low-carbon steel bars were produced by caliber rolling, and the impact and tensile properties were investigated. Initial samples with two different microstructures, ferrite-pearlite and martensite (or bainite), were prepared and then caliber rolling was conducted at 500 °C. The microstructures in the rolled bars consisted of an elongated UFG structure with a strong α-fiber texture. The rolled bar consisting of spheroidal cementite particles that distributed uniformly in the elongated ferrite matrix of transverse grain sizes 0.8 to 1.0 μm exhibited the best strength-ductility balance and impact properties. Although the yield strength in the rolled bar increased 2.4 times by grain refinement, the upper-shelf energy did not change, and its value was maintained from 100 °C to -40 °C. In the rolled bars, cracks during an impact test branched parallel to the longitudinal direction of the test samples as temperatures decreased. Delamination caused by such crack branching appeared, remarkably, near the ductile-to-brittle transition temperature (DBTT). The effect of delamination on the impact properties was associated with crack propagation on the basis of the microstructural features in the rolled bars. In conclusion, the strength-toughness balance is improved by refining crystal grains and controlling their shape and orientation; in addition, delamination effectively enhances the low-temperature toughness.

  3. A numerical study of the rolling friction between a microsphere and a substrate considering the adhesive effect

    NASA Astrophysics Data System (ADS)

    Zhang, Yuyan; Wang, Xiaoli; Li, Hanqing; Yang, Weixu

    2016-01-01

    A numerical model of the rolling friction between a microsphere and a substrate is established by introducing the adhesion hysteresis between the front and rear sides of the contact region into Zhang’s adhesive contact model. Effects of the size ratio which is defined as the sphere radius divided by the equilibrium separation, relative amount of adhesion hysteresis and Tabor parameter on the dimensionless maximum rolling friction torque in the case of zero normal force are inspected, and the quantitative relationship between the maximum rolling friction torque and the normal force is achieved. Results indicate that due to adhesion hysteresis at microscale, the dimensionless maximum rolling friction torque at zero normal force is not zero, which not only increases with decreasing size ratio, showing clear size effects, but also increases with increasing relative amount of adhesion hysteresis and Tabor parameter. In addition, the maximum rolling friction torque at microscale presents a sublinear relationship with the normal force, and the exponent of the normal force is influenced by the size ratio, relative amount of adhesion hysteresis and Tabor parameter, which are remarkably different from the superlinear relationship at macroscale.

  4. Effect of skin-pass rolling direction on magnetic properties of semiprocessed nonoriented electrical steel sheets

    SciTech Connect

    Kurosaki, Y.; Shimazu, T.; Shiozaki, M.

    1999-09-01

    Effect of skin-pass rolling direction on magnetic properties and directionality in semiprocessed nonoriented electrical steel sheets produced by skin-pass rolling process was studied. Skin-pass rolling direction greatly affects magnetic properties and directionality. By control of skin-pass rolling direction, the value of B{sub 50} in the required directions such as 0{degree}, 90{degree} and circumferential direction can be adjusted and the value of B{sub 50} is higher than that of the usual skin-pass rolling direction of 0{degree}. The textures of the steel sheets developed after batch annealing varied with the skin-pass rolling directions and this result indicates that the residual strain energy by skin-pass rolling varies with skin-pass rolling directions.

  5. The effects of myofascial release with foam rolling on performance.

    PubMed

    Healey, Kellie C; Hatfield, Disa L; Blanpied, Peter; Dorfman, Leah R; Riebe, Deborah

    2014-01-01

    In the last decade, self-myofascial release has become an increasingly common modality to supplement traditional methods of massage, so a masseuse is not necessary. However, there are limited clinical data demonstrating the efficacy or mechanism of this treatment on athletic performance. The purpose of this study was to determine whether the use of myofascial rollers before athletic tests can enhance performance. Twenty-six (13 men and 13 women) healthy college-aged individuals (21.56 ± 2.04 years, 23.97 ± 3.98 body mass index, 20.57 ± 12.21 percent body fat) were recruited. The study design was a randomized crossover design in which subject performed a series of planking exercises or foam rolling exercises and then performed a series of athletic performance tests (vertical jump height and power, isometric force, and agility). Fatigue, soreness, and exertion were also measured. A 2 × 2 (trial × gender) analysis of variance with repeated measures and appropriate post hoc was used to analyze the data. There were no significant differences between foam rolling and planking for all 4 of the athletic tests. However, there was a significant difference between genders on all the athletic tests (p ≤ 0.001). As expected, there were significant increases from pre to post exercise during both trials for fatigue, soreness, and exertion (p ≤ 0.01). Postexercise fatigue after foam rolling was significantly less than after the subjects performed planking (p ≤ 0.05). The reduced feeling of fatigue may allow participants to extend acute workout time and volume, which can lead to chronic performance enhancements. However, foam rolling had no effect on performance.

  6. Effect of Dynamic Rolling Oscillations on Twin Tail Buffet Response

    NASA Technical Reports Server (NTRS)

    Sheta, Essam F.; Kandil, Osama A.

    1999-01-01

    The effect of dynamic rolling oscillations of delta-wing/twin-tail configuration on twin-tail buffet response is investigated. The computational model consists of a sharp-edged delta wing of aspect ratio one and swept-back flexible twin tail with taper ratio of 0.23. The configuration model is statically pitched at 30 deg. angle of attack and then forced to oscillate in roll around the symmetry axis at a constant amplitude of 4 deg. and reduced frequency of pi and 2(pi). The freestream Mach number and Reynolds number are 0.3 and 1.25 million, respectively. This multidisciplinary problem is solved using three sets of equations on a dynamic multi-block grid structure. The first set is the unsteady, full Navier-Stokes equations, the second set is the aeroelastic equations for coupled bending and torsion vibrations of the tails, and the third set is the grid-displacement equations. The configuration is investigated for inboard position of the twin tails which corresponds to a separation distance between the twin tails of 33% wing span. The computed results are compared with the results of stationary configuration, which previously have been validated using experimental data. The results conclusively showed that the rolling oscillations of the configuration have led to higher loads, higher deflections, and higher excitation peaks than those of the stationary configuration. Moreover, increasing the reduced frequency has led to higher loads and excitation peaks and lower bending and torsion deflections and acceleration.

  7. Effect of Microstructural Anisotropy on the Electrochemical Behavior of Rolled Mild Steel

    NASA Astrophysics Data System (ADS)

    Choudhary, S.; Nanda, V.; Shekhar, S.; Garg, A.; Mondal, K.

    2017-01-01

    Warm rolling of a mild steel at 600 °C generates a microstructural anisotropy in the different planes corresponding to rolling direction, normal direction and transverse direction manifested by differences in the grain structure and the type of grain boundaries. The work concentrates on studying the effect of this microstructural anisotropy on the electrochemical behavior of the steel plates using microscopic examination and electron backscattered diffraction. The results show that the corrosion behavior of the samples depends mainly on the fraction of high-angle grain boundaries or corresponding average grain size, which, in turn, depends on the degree of deformation on different planes determined by the extent of thickness reduction. On the other hand, low-angle grain boundaries have little effect on the corrosion of all the three different planes.

  8. A study of energy-size relationship and wear rate in a lab-scale high pressure grinding rolls unit

    NASA Astrophysics Data System (ADS)

    Rashidi Dashtbayaz, Samira

    This study is focused on two independent topics of energy-size relationship and wear-rate measurements on a lab-scale high pressure grinding rolls (HPGR). The first part of this study has been aimed to investigate the influence of the operating parameters and the feed characteristics on the particle-bed breakage using four different ore samples in a 200 mm x 100 mm lab-scale HPGR. Additionally, multistage grinding, scale-up from a lab-scale HPGR, and prediction of the particle size distributions have been studied in detail. The results obtained from energy-size relationship studies help with better understanding of the factors contributing to more energy-efficient grinding. It will be shown that the energy efficiency of the two configurations of locked-cycle and open multipass is completely dependent on the ore properties. A test procedure to produce the scale-up data is presented. The comparison of the scale-up factors between the data obtained on the University of Utah lab-scale HPGR and the industrial machine at the Newmont Boddington plant confirmed the applicability of lab-scale machines for trade-off studies. The population balance model for the simulation of product size distributions has shown to work well with the breakage function estimated through tests performed on the HPGR at high rotational speed. Selection function has been estimated by back calculation of population balance model with the help of the experimental data. This is considered to be a major step towards advancing current research on the simulation of particle size distribution by using the HPGR machine for determining the breakage function. Developing a technique/setup to measure the wear rate of the HPGR rolls' surface is the objective of the second topic of this dissertation. A mockup was initially designed to assess the application of the linear displacement sensors for measuring the rolls' weight loss. Upon the analysis of that technique and considering the corresponding sources of

  9. A disposable, roll-to-roll hot-embossed inertial microfluidic device for size-based sorting of microbeads and cells.

    PubMed

    Wang, Xiao; Liedert, Christina; Liedert, Ralph; Papautsky, Ian

    2016-05-21

    Inertial microfluidics has been a highly active area of research in recent years for high-throughput focusing and sorting of synthetic and biological microparticles. However, existing inertial microfluidic devices always rely on microchannels with high-aspect-ratio geometries (channel width w < channel height h) and small cross-sections (w×h < 50 × 100 μm(2)). Such deep and small structures increase fabrication difficulty and can limit manufacturing by large-scale and high-throughput production approaches such as roll-to-roll (R2R) hot embossing. In this work, we present a novel inertial microfluidic device using only a simple and low-aspect-ratio (LAR) straight microchannel (w > h) to achieve size-based sorting of microparticles and cells. The simple LAR geometry of the device enables successful high-throughput fabrication using R2R hot embossing. With optimized flow conditions and channel dimensions, we demonstrate continuous sorting of a mixture of 15 μm and 10 μm diameter microbeads with >97% sorting efficiency using the low-cost and disposable R2R chip. We further demonstrate size-based sorting of bovine white blood cells, demonstrating the ability to process real cellular samples in our R2R chip. We envision that this R2R hot-embossed inertial microfluidic chip will serve as a powerful yet low-cost and disposable tool for size-based sorting of synthetic microparticles in industrial applications or cellular samples in cell biology research and clinical diagnostics.

  10. T Strip Properties Fabricated by Powder Rolling Method

    NASA Astrophysics Data System (ADS)

    Hong, Jae-Keun; Lee, Chae-Hun; Kim, Jeoung-Han; Yeom, Jong-Taek; Park, Nho-Kwang

    In the present study, the characteristics of the Ti powders fabricated by Hydride-Dehydride (HDH) were analyzed in terms of particle shape, size and size distribution. Ti powders were subjected to roll compaction and their microstructure and green densities were evaluated in terms of particle size, powder morphology, roll gap and rolling speed. Effects of blending elements having different powder sizes on densification properties were analyzed. The strip thickness was proportional to the roll gap up to 0.9 mm and the density of titanium strip was decreased with the increase in roll gap. As the roll speed increased, the strip density and thickness were decreased by using -200 mesh Ti powder. However, the effect of rolling speed for -400 mesh Ti powder was not greater than that of -200 mesh powder. The highest density by 93% was achieved by using -400 mesh Ti powder at 0.1 mm roll gap, however edge cracks and alligator cracks were occurred.

  11. The effect of mold materials on the overlay accuracy of a roll-to-roll imprinting system using UV LED illumination within a transparent mold

    NASA Astrophysics Data System (ADS)

    Choi, Sungwoo; Kook, YunHo; Kim, ChulHo; Yoo, SoonSung; Park, Kwon-Shik; Kim, Seok-min; Kang, Shinill

    2016-06-01

    Although several studies on the roll-to-roll (R2R) imprinting process have reported achieving flexible electronics, improving the alignment accuracy in the overlay process of R2R imprinting is recognized as the biggest problem for the commercialization of this technology. For an overlay technique with high alignment accuracy, it is essential to develop a roll mold with high positional accuracy. In this study, a method for fabricating a roll mold with high positional accuracy is proposed by wrapping a thin glass substrate flexible mold around the transparent roll base, because it can provide higher mechanical strength and thermal stability than a conventional polymer substrate. To confirm the usability of the proposed process, the prepared roll mold was used to fabricate a test pattern of thin-film transistor backplane for a rollable display. The positional and overlay accuracy of the roll mold with the proposed thin glass substrate flexible mold were compared with the roll mold with a conventional polymer substrate flexible mold. Large-area transparent flexible molds with a size of 470  ×  370 mm were fabricated by an ultraviolet (UV) imprinting process on thin glass and polyethylene terephthalate substrates, and these flexible molds were wrapped around a roll base of 125 mm radius through a precision alignment process. After an anti-adhesion treatment and the wrapping process, the roll mold with the polymer substrate showed a ~180 μm positional error, whereas the thin glass substrate showed a ~30 μm positional error. After the overlay process using the R2R imprinting system with the alignment system, an average overlay error of ~3 μm was obtained when the thin glass flexible wrapped roll mold was used, whereas a ~22 μm overlay error was obtained when the polymer substrate flexible wrapped roll mold was used.

  12. Rolling and pitching oscillating foil propulsion in ground effect.

    PubMed

    Perkins, Matthew D; Elles, Dane; Badlissi, George; Mivehchi, Amin; Dahl, Jason; Licht, Stephen

    2017-09-04

    In this paper, we investigate the effect of operating near a solid boundary on the forces produced by harmonically oscillating thrust generating foils. A rolling and pitching foil was towed in a freshwater tank in a series of experiments with varying kinematics. Hydrodynamic forces and torques were measured in the free stream and at varying distances from a solid boundary, and changes in mean lift and thrust were found when the foil approached the boundary. The magnitude of this ground effect exhibited a strong nonlinear dependence on the distance between the foil and the boundary. Significant effects were found within three chord lengths of the boundary, and ground effect can be induced at greater distances from the boundary by biasing the tip of the foil toward the boundary. Lift coefficients changed by as much as 0.2 at the closest approach to the ground, with changes ≥0.05 for all cases across Strouhal number ranging from 0.3 to 0.6, and nominal maximum angle of attack ranging from 20° to 40°. The ubiquity of the ground effect in high thrust kinematics suggests that the ground effect can provide a passive obstacle avoidance capability for foil propelled vehicles. By comparison to previous experimental work, we find that the ground effect experienced by a high-aspect ratio rolling and pitching foil is a fully three-dimensional phenomenon, as it is not accurately predicted when two-dimensional flow and/or two-dimensional kinematics are enforced. While two dimensional foil kinematics are more easily modeled for numerical studies, three-dimensional foil kinematics may be more practical for real world implementation in underwater vehicles. © 2017 IOP Publishing Ltd.

  13. Rolling Shutter Effect aberration compensation in Digital Holographic Microscopy

    NASA Astrophysics Data System (ADS)

    Monaldi, Andrea C.; Romero, Gladis G.; Cabrera, Carlos M.; Blanc, Adriana V.; Alanís, Elvio E.

    2016-05-01

    Due to the sequential-readout nature of most CMOS sensors, each row of the sensor array is exposed at a different time, resulting in the so-called rolling shutter effect that induces geometric distortion to the image if the video camera or the object moves during image acquisition. Particularly in digital holograms recording, while the sensor captures progressively each row of the hologram, interferometric fringes can oscillate due to external vibrations and/or noises even when the object under study remains motionless. The sensor records each hologram row in different instants of these disturbances. As a final effect, phase information is corrupted, distorting the reconstructed holograms quality. We present a fast and simple method for compensating this effect based on image processing tools. The method is exemplified by holograms of microscopic biological static objects. Results encourage incorporating CMOS sensors over CCD in Digital Holographic Microscopy due to a better resolution and less expensive benefits.

  14. Effect of roll number on the statistics of turbulent Taylor-Couette flow

    NASA Astrophysics Data System (ADS)

    Ostilla-Mónico, Rodolfo; Lohse, Detlef; Verzicco, Roberto

    2016-09-01

    A series of direct numerical simulations in large computational domains has been performed in order to probe the spatial feature robustness of the Taylor rolls in turbulent Taylor-Couette flow. The latter is the flow between two coaxial independently rotating cylinders of radius ri and ro, respectively. Large axial aspect ratios Γ =7 -8 [with Γ =L /(ro-ri) , and L the axial length of the domain] and a simulation with Γ =14 were used in order to allow the system to select the most unstable wave number and to possibly develop multiple states. The radius ratio was taken as η =ri/ro=0.909 , the inner cylinder Reynolds number was fixed to Rei=3.4 ×104 , and the outer cylinder was kept stationary, resulting in a frictional Reynolds number of Reτ≈500 , except for the Γ =14 simulation where Rei=1.5 ×104 and Reτ≈240 . The large-scale rolls were found to remain axially pinned for all simulations. Depending on the initial conditions, stable solutions with different number of rolls nr and roll wavelength λz were found for Γ =7 . The effect of λz and nr on the statistics was quantified. The torque and mean flow statistics were found to be independent of both λz and nr, while the velocity fluctuations and energy spectra showed some box-size dependence. Finally, the axial velocity spectra were found to have a very sharp dropoff for wavelengths larger than λz, while for the small wavelengths they collapse.

  15. Effect of Flaw Removal on Billets in Rolling

    NASA Astrophysics Data System (ADS)

    Yoshida, Kazunari; Shinohara, Tetsuo

    2007-05-01

    High-quality wires, which are used for components such as valve springs of automobiles, are fabricated by rolling and drawing. Even a minute flaw on the surface of the wire leads to a significant decrease in fatigue strength. It is possible to decrease the number of surface flaws during some of the rolling processes; however in most cases, it is difficult to remove flaws. Under such circumstances, high-quality wires are fabricated, at many wire manufacturing factories, by rolling and drawing after removing surface flaws on the raw material. However, the flaw removal process is carried out relying on the experience of onsite workers; many of the mechanisms underlying flaw removal have not been clarified. In this study, billet and wire that have traces formed during flaw removal were subjected to rolling to investigate the behavior of deformation and the recovery of the flaw-removal traces. When flaw-removal traces exist on a billet surface that comes into contact with the roll used in rolling, the traces are removed without difficulty. However, when the flaw-removal traces exist on a surface that does not come into contact with the roll, the traces tend to become wrinkles due to compression from the upper and lower directions. Therefore, when removing the surface flaw on billet before rolling, it is important to remove flaw part thinly.

  16. Post-roll effects on attitude perception: "the Gillingham Illusion".

    PubMed

    Ercoline, W R; Devilbiss, C A; Yauch, D W; Brown, D L

    2000-05-01

    Several aircraft each year are lost because of an unexplained collision with the ground. The attitude of most of these aircraft prior to impact was nose-low and with excessive bank, i.e., greater than 90 degrees . Prior to these accidents, each aircraft was noted as either changing heading or making an abrupt roll. Could there be some underlying tendency for the pilot to make unnoticed stick inputs after completing a roll from one bank angle to another? Since ground-based flight simulators cannot create the true sensation of rolling an aircraft from one side to the other, the instrumented CALSPAN NT-33 aircraft was used for this study. Six pilots were given a series of three roll rates and two head positions while the aircraft automatically changed bank from 45 degrees of bank in one direction to 45 degrees of bank in the opposite direction. The subject's view of the external visual scene was restricted with a blue-amber vision restricting transparency combination. All attitude-indicating instruments were blanked, requiring the subjects to make stick inputs based on their vestibular (somatosensory) feedback. Subjects experienced a consistent tendency to increase bank angle after given control of the aircraft immediately following the roll maneuver, while thinking they were maintaining a constant bank angle. In some cases, the pilots rolled the aircraft completely inverted. When pilots rely on their perception of bank, following a roll, they will inadvertently increase their bank in the direction of the previous roll.

  17. The effect of cold rolling parameters on the recrystallization texture of non-oriented electrical steel

    NASA Astrophysics Data System (ADS)

    Kawamata, R.; Kubota, T.; Yamada, K.

    1997-12-01

    The effect of cold rolling condition on magnetic properties of non-oriented electrical steel was investigated. For evaluation of cold roiling condition, utilizing rolling shape factor (RSF) was proposed. In the case of small RSF, magnetic induction was improved. Development of ND ∥ <111< components was suppressed in the recrystallized texture near the surface, and the vicinity of the {100}<001> component was developed after grain growth. The relation between RSF and cold-rolling condition was examined by computer simulation; such results were attributed to the increment of shear strain in the surface texture. Magnetic properties would be improved by adequate control of cold-rolling condition.

  18. Effect of asymmetric hot rolling on texture, microstructure and magnetic properties in a non-grain oriented electrical steel

    NASA Astrophysics Data System (ADS)

    Chen, S.; Butler, J.; Melzer, S.

    2014-11-01

    In this study, both asymmetric hot rolling (AHR) and conventional hot rolling (CHR) were carried out to study the effect of the hot rolling conditions on the evolution of the texture and microstructure in a non-grain oriented (NGO) steel. The microstructure and texture in the subsequent processing stages were characterised and related to the final magnetic properties. The results show that AHR, compared with CHR, tends to homogenise texture through thickness of the hot band strips. AHR results in a higher fraction of the θ-fibre ({0 0 1}) and a lower fraction of the γ-fibre ({1 1 1}) in the hot band strips, which are favourable features in relation to the magnetic properties of the strip. However, the favourable features observed in hot rolled AHR strips are eliminated after cold rolling and annealing. Contrarily, the required θ-fibre is decreased and the unwanted γ-fibre is intensified in the AHR sheet after cold rolling and their strength is maintained in the subsequent process steps. On the other hand, AHR does not produce a discernible change in the grain size in the hot band annealed strip and in the final annealed sheet, except that the magnetic anisotropy in the AHR is improved after skin pass and extra annealing as the result of the redistribution of the texture components within the θ-fibre, no significant improvement of the magnetic properties as a direct consequence of the application of asymmetric hot rolling has been observed under the current AHR experimental conditions.

  19. Effects of rolling on the ductility of 80% tungsten heavy alloy

    SciTech Connect

    Lavender, C.A.; Gurwell, W.E.

    1992-11-01

    Relations between transverse tensile ductility and rolling and annealing schedules were investigated for solid-state sintered and annealed 80%W8%Ni-2%Fe heavy alloy rolled at 900C or 1150C with varying reductions between anneals at either 1150C or 1400C. Final anneals and a solution heat treatment were employed prior to tensile testing. Metallographic and fractographic analyses were performed to determine relations between microstructure and physical properties. Multiple 1400C intermediate anneals with a maximum 60% rolling reduction produced higher transverse tensile elongations than rolled with a higher final reduction, 86%. Tensile elongation differences were attributed to the recrystallized intra-particle W grain sizes achieved during the final anneal. Materials given a maximum of 60% reduction before final anneal had fewer intra-particle W grains and therefore higher ductilities. For materials rolled at 900C or 1150C, no differences in transverse tensile elongation were observed. 1150C intermediate anneals had consistently lower ductility. 900C rolling produced slightly higher elongations than 1150C rolling, but only when the material was annealed at 1455C. Tensile yield and ultimate strengths did not vary greatly with rolling and intermediate annealing conditions. The edge cracking correlated with observed lateral spread and the material softness.

  20. Effect Sizes, Confidence Intervals, and Confidence Intervals for Effect Sizes

    ERIC Educational Resources Information Center

    Thompson, Bruce

    2007-01-01

    The present article provides a primer on (a) effect sizes, (b) confidence intervals, and (c) confidence intervals for effect sizes. Additionally, various admonitions for reformed statistical practice are presented. For example, a very important implication of the realization that there are dozens of effect size statistics is that "authors must…

  1. Effect of the defect initial shape on the fatigue lifetime of a continuous casting machine roll

    NASA Astrophysics Data System (ADS)

    Yasniy, Oleh P.; Lapusta, Yuri

    2016-08-01

    The article deals with the influence of the defect initial shape on the residual lifetime of a continuous casting machine roll made of 25Cr1MoV steel. Based on this approach, previously proposed by some authors, the growth of the surface fatigue crack was modeled in a roll under loading and temperature conditions that are close to operational ones, taking into account the statistical distribution of the C parameter of Paris' equation. Dependencies of the continuous casting machines roll fatigue lifetime on the initial defect shape and critical defect sizes are obtained.

  2. Effects of warm-up on hamstring muscles stiffness: Cycling vs foam rolling.

    PubMed

    Morales-Artacho, A J; Lacourpaille, L; Guilhem, G

    2017-01-26

    This study investigated the effects of active and/or passive warm-up tasks on the hamstring muscles stiffness through elastography and passive torque measurements. On separate occasions, fourteen males randomly completed four warm-up protocols comprising Control, Cycling, Foam rolling, or Cycling plus Foam rolling (Mixed). The stiffness of the hamstring muscles was assessed through shear wave elastography, along with the passive torque-angle relationship and maximal range of motion (ROM) before, 5, and 30 minutes after each experimental condition. At 5 minutes, Cycling and Mixed decreased shear modulus (-10.3% ± 5.9% and -7.7% ± 8.4%, respectively; P≤.0003, effect size [ES]≥0.24) and passive torque (-7.17% ± 8.6% and -6.2% ± 7.5%, respectively; P≤.051, ES≥0.28), and increased ROM (+2.9% ± 2.9% and +3.2% ± 3.5%, respectively; P≤.001, ES≥0.30); 30 minutes following Mixed, shear modulus (P=.001, ES=0.21) and passive torque (P≤.068, ES≥0.2) were still slightly decreased, while ROM increased (P=.046, ES=0.24). Foam rolling induced "small" immediate short-term decreases in shear modulus (-5.4% ± 5.7% at 5 minutes; P=.05, ES=0.21), without meaningful changes in passive torque or ROM at any time point (P≥.12, ES≤0.23). These results suggest that the combined warm-up elicited no acute superior effects on muscle stiffness compared with cycling, providing evidence for the key role of active warm-up to reduce muscle stiffness. The time between warm-up and competition should be considered when optimizing the effects on muscle stiffness.

  3. Effect of intermediate annealing on the microstructure and mechanical property of ZK60 magnesium alloy produced by twin roll casting and hot rolling

    SciTech Connect

    Chen, Hongmei; Zang, Qianhao; Yu, Hui; Zhang, Jing; Jin, Yunxue

    2015-08-15

    Twin roll cast (designated as TRC in short) ZK60 magnesium alloy strip with 3.5 mm thickness was used in this paper. The TRC ZK60 strip was multi-pass rolled at different temperatures, intermediate annealing heat treatment was performed when the thickness of the strip changed from 3.5 mm to 1 mm, and then continued to be rolled until the thickness reached to 0.5 mm. The effect of intermediate annealing during rolling process on microstructure, texture and room temperature mechanical properties of TRC ZK60 strip was studied by using OM, TEM, XRD and electronic universal testing machine. The introduction of intermediate annealing can contribute to recrystallization in the ZK60 sheet which was greatly deformed, and help to reduce the stress concentration generated in the rolling process. Microstructure uniformity and mechanical properties of the ZK60 alloy sheet were also improved; in particular, the room temperature elongation was greatly improved. When the TRC ZK60 strip was rolled at 300 °C and 350 °C, the room temperature elongation of the rolled sheet with 0.5 mm thickness which was intermediate annealed during the rolling process was increased by 95% and 72% than that of no intermediate annealing, respectively. - Highlights: • Intermediate annealing was introduced during hot rolling process of twin roll cast ZK60 alloy. • Intermediate annealing can contribute to recrystallization and reduce the stress concentration in the deformed ZK60 sheet. • Microstructure uniformity and mechanical properties of the ZK60 sheet were improved, in particular, the room temperature elongation. • The elongation of the rolled ZK60 sheet after intermediate annealed was increased by 95% and 72% than that of no intermediate annealing.

  4. Population sizes and dispersal pattern of tsetse flies: rolling on the river?

    PubMed

    Bouyer, J; Balenghien, T; Ravel, S; Vial, L; Sidibé, I; Thévenon, S; Solano, P; De Meeûs, T

    2009-07-01

    The West African trypanosomoses are mostly transmitted by riverine species of tsetse fly. In this study, we estimate the dispersal and population size of tsetse populations located along the Mouhoun river in Burkina Faso where tsetse habitats are experiencing increasing fragmentation caused by human encroachment. Dispersal estimated through direct (mark and recapture) and indirect (genetic isolation by distance) methods appeared consistent with one another. In these fragmented landscapes, tsetse flies displayed localized, small subpopulations with relatively short effective dispersal. We discuss how such information is crucial for designing optimal strategies for eliminating this threat. To estimate ecological parameters of wild animal populations, the genetic measures are both a cost- and time-effective alternative to mark-release-recapture. They can be applied to other vector-borne diseases of medical and/or economic importance.

  5. The effect of cold rolling parameters on the recrystallization texture of non-oriented electrical steel

    SciTech Connect

    Kawamata, R.; Kubota, T.; Yamada, K.

    1997-12-01

    The effect of cold rolling condition on magnetic properties of non-oriented electrical steel was investigated. For evaluation of cold rolling condition, utilizing rolling shape factor (RSF) was proposed. In the case of small RSF, magnetic induction was improved. Development of ND {parallel} <111> components was suppressed in the recrystallized texture near the surface, and the vicinity of the {l_brace}100{r_brace}<001> component was developed after grain growth. The relation between RSF and cold-rolling condition was examined by computer simulation; such results were attributed to the increment of shear strain in the surface texture. Magnetic properties would be improved by adequate control of cold-rolling condition.

  6. Effect of Shear Deformation on Closure of a Central Void in Thin-Strip Rolling

    NASA Astrophysics Data System (ADS)

    Park, Jong-Jin

    2016-01-01

    Central voids or voids at the middle layer are often found in thin strips produced by twin-roll casting. These strips are in general so thin that they are unable to take a required reduction in thickness to close the voids. In the present investigation, equal-speed rolling and differential-speed rolling were compared to assess the effect of differential speed on closure of the voids by the rigid-plastic finite-element analysis. As a result, shear deformation developed in differential-speed rolling was found to reduce the reduction in thickness required for void closure. An increase in speed ratio, length of deformation zone, or friction coefficient at the interface expedited the progress in void closure. However, as the speed ratio exceeded thickness ratio, a portion of rolling power was dissipated extensively by excessive slip at the interface. Moreover, tensile stress developed which would cause cracks in the strip.

  7. Microstructure versus substructure size effect

    NASA Astrophysics Data System (ADS)

    Ghassemali, Ehsan; Jarfors, Anders E. W.; Tan, Ming-Jen; Wah, Chua Beng

    2016-10-01

    In metal deformation, size effect is generally attributed to the interactive effect of grain size and specimen dimension. This work shows, however, that relative substructure dimensions should also be considered. Micro-compression tests on the micro-pins having different grain sizes revealed no significant size effect with respect to the mechanical behavior, even if the number of grains over the diameter of the micro-pins falls below its critical value. To justify the reason laying under this fact, a recovery annealing cycle was applied on the micro-pins to change the substructure properties without altering the mean grain size. A surprising drop in the flow stress of the recovery-annealed micro-pins implied the importance of considering subgrain size rather than grain size over the diameter of component for the size effect investigation.

  8. Effects of Hot Rolling on Low-Cycle Fatigue Properties of Zn-22 wt.% Al Alloy at Room Temperature

    NASA Astrophysics Data System (ADS)

    Dong, X. H.; Cao, Q. D.; Ma, S. J.; Han, S. H.; Tang, W.; Zhang, X. P.

    2016-09-01

    The effects of the reduction ratio (RR) on the low-cycle fatigue (LCF) properties of the Zn-22 wt.% Al (Zn-22Al) alloy were investigated. Various grain sizes from 0.68 to 1.13 μm were obtained by controlled RRs. Tensile and LCF tests were carried out at room temperature. Superplasticity and cyclic softening were observed. Strength and ductility of the rolled Zn-22Al alloy increased with the RR, owing to the decrease in its grain size. The RR did not affect the cyclic softening behavior of the alloy. The fatigue life of the alloy decreased with increasing strain amplitude, while the fatigue life first decreased and then increased with increasing RR. The longest fatigue life was observed for the alloy rolled at a RR of 60%. A bilinear Coffin-Manson relationship was observed to hold true for this alloy.

  9. Effects of rolling temperature and subsequent annealing on mechanical properties of ultrafine-grained Cu–Zn–Si alloy

    SciTech Connect

    Zhang, Xiangkai; Yang, Xuyue; Chen, Wei; Qin, Jia; Fouse, Jiaping

    2015-08-15

    The effects of rolling temperature and subsequent annealing on mechanical properties of Cu–Zn–Si alloy were investigated by using X-ray diffraction, transmission electron microscope, electron back scattered diffraction and tensile tests. The Cu–Zn–Si alloy has been processed at cryogenic temperature (approximately 77 K) and room temperature up to different rolling strains. It has been identified that the cryorolled Cu–Zn–Si alloy samples show a higher strength compared with those room temperature rolled samples. The improved strength of cryorolled samples is resulted from grain size effect and higher densities of dislocations and deformation twins. And subsequent annealing, as a post-heat treatment, enhanced the ductility. An obvious increase in uniform elongation appears when the volume fraction of static recrystallization grains exceeds 25%. The strength–ductility combination of the annealed cryorolled samples is superior to that of annealed room temperature rolled samples, owing to the finer grains, high fractions of high angle grain boundaries and twins. - Highlights: • An increase in hardness of Cu–Zn–Si alloy is noticed during annealing process. • Thermal stability is reduced in Cu–Zn–Si alloy by cryorolling. • An obvious enhancement in UE is noticed when fraction of SRX grains exceeds 25%. • A superior strength–ductility combination is achieved in the cryorolling samples.

  10. Effective sizes for subdivided populations

    SciTech Connect

    Chesser, R.K. Univ. of Georgia, Athens, GA ); Rhodes, O.E. Jr.; Sugg, D.W.; Schnabel, A. )

    1993-12-01

    Many derivations of effective population sizes have been suggested in the literature; however, few account for the breeding structure and none can readily be expanded to subdivided populations. Breeding structures influence gene correlations through their effects on the number of breeding individuals of each sex, the mean number of progeny per female, and the variance in the number of progeny produced by males and females. Additionally, hierarchical structuring in a population is determined by the number of breeding groups and the migration rates of males and females among such groups. This study derives analytical solutions for effective sizes that can be applied to subdivided populations. Parameters that encapsulate breeding structure and subdivision are utilized to derive the traditional inbreeding and variance effective sizes. Also, it is shown that effective sizes can be determined for any hierarchical level of population structure for which gene correlations can accrue. Derivations of effective sizes for the accumulation of gene correlations within breeding groups (coancestral effective size) and among breeding groups (intergroup effective size) are given. The results converge to traditional single population measures when similar assumptions are applied. In particular, inbreeding and intergroup effective sizes are shown to be special cases of the coancestral effective size, and intergroup and variance effective sizes will be equal if the population census remains constant. Instantaneous solutions for effective size, at any time after gene correlation begins to accrue, are given in terms of traditional F statistics or transition equations. All effective sizes are shown to converge upon a common asymptotic value when breeding tactics and migration rates are constant. The asymptotic effective size can be expressed in terms of the fixation indices and the number of breeding groups; however, the rate of approach to the asymptote is dependent upon dispersal rates.

  11. The effect of sinusoidal rolling ground motion on lifting biomechanics.

    PubMed

    Ning, Xiaopeng; Mirka, Gary A

    2010-12-01

    The objective of this study was to quantify the effects of ground surface motion on the biomechanical responses of a person performing a lifting task. A boat motion simulator (BMS) was built to provide a sinusoidal ground motion (simultaneous vertical linear translation and a roll angular displacement) that simulates the deck motion on a small fishing boat. Sixteen participants performed lifting, lowering and static holding tasks under conditions of two levels of mass (5 and 10 kg) and five ground moving conditions. Each ground moving condition was specified by its ground angular displacement and instantaneous vertical acceleration: A): +6°, -0.54 m/s(2); B): +3°, -0.27 m/s(2); C): 0°, 0m/s(2); D): -3°, 0.27 m/s(2); and E): -6°, 0.54 m/s(2). As they performed these tasks, trunk kinematics were captured using the lumbar motion monitor and trunk muscle activities were evaluated through surface electromyography. The results showed that peak sagittal plane angular acceleration was significantly higher in Condition A than in Conditions C, D and E (698°/s(2) vs. 612-617°/s(2)) while peak sagittal plane angular deceleration during lowering was significantly higher in moving conditions (conditions A and E) than in the stationary condition C (538-542°/s(2) vs. 487°/s(2)). The EMG results indicate that the boat motions tend to amplify the effects of the slant of the lifting surface and the external oblique musculature plays an important role in stabilizing the torso during these dynamic lifting tasks. Copyright © 2010 Elsevier Ltd. All rights reserved.

  12. Effect of microalloying elements on the structure and properties of low-carbon and ultralow-carbon cold-rolled steels

    NASA Astrophysics Data System (ADS)

    Girina, O. A.; Fonshtein, N. M.; Storozheva, L. M.

    1994-03-01

    Cold-rolled steels used for the forged components of automobiles should exhibit high, partly mutually-exclusive properties: high forgeability with desirably high strength, resistance to aging combined with hardenability at temperatures for drying paint coatings, etc. Satisfaction of these requirements is provided to a considerable degree by microalloying. The final mechanical properties of cold-rolled steel depend on such structural parameters of hot-rolled strip as texture, the amount of dissolved C and N atoms in α-solid solution, and ferrite grain size. With constant hot rolling production schedules these structural parameters are governed by steel composition, in particular by the type of microalloying. In this work the effect is considered for dispersed microalloying elements, i.e., phosphorus, boron, titanium, and nïobium, on the final mechanical properties of low- and ultralow-carbon steels.

  13. Effect of Rolling Bearing Refurbishment and Restoration on Bearing Life and Reliability

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.; Branzai, Emanuel V.

    2005-01-01

    For nearly four decades it has been a practice in commercial and military aircraft application that rolling-element bearings removed at maintenance or overhaul be reworked and returned to service. The work presented extends previously reported bearing life analysis to consider the depth (Z(45)) to maximum shear stress (45) on stressed volume removal and the effect of replacing the rolling elements with a new set. A simple algebraic relationship was established to determine the L(10) life of bearing races subject to bearing rework. Depending on the extent of rework and based upon theoretical analysis, representative life factors (LF) for bearings subject to rework ranged from 0.87 to 0.99 the lives of new bearings. Based on bearing endurance data, 92 percent of the bearing sets that would be subject to rework would result in L(10) lives equaling and/or exceeding that predicted for new bearings with the remaining 8 percent having the potential to achieve the analytically predicted life of new bearings when one of the rings is replaced at rework.. The potential savings from bearing rework varies from 53 to 82 percent that of new bearings depending on the cost, size and complexity of the bearing.

  14. Size Effect in Continuum Modeling

    SciTech Connect

    Lu, Wei-Yang; James W. Foulk; Huestis, Edwin M.; Connelly, Kevin; Song, Bo; Yang, Nancy Y. C.

    2008-09-01

    The mechanical properties of some materials (Cu, Ni, Ag, etc.) have been shown to develop strong dependence on the geometric dimensions, resulting in a size effect. Several theories have been proposed to model size effects, but have been based on very few experiments conducted at appropriate scales. Some experimental results implied that size effects are caused by increasing strain gradients and have been used to confirm many strain gradient theories. On the other hand, some recent experiments show that a size effect exists in the absence of strain gradients. This report describes a brief analytical and experimental study trying to clarify the material and experimental issues surrounding the most influential size-effect experiments by Fleck et al (1994). This effort is to understand size effects intended to further develop predictive models.

  15. Effective Sizes for Subdivided Populations

    PubMed Central

    Chesser, R. K.; Rhodes-Jr., O. E.; Sugg, D. W.; Schnabel, A.

    1993-01-01

    Many derivations of effective population sizes have been suggested in the literature; however, few account for the breeding structure and none can readily be expanded to subdivided populations. Breeding structures influence gene correlations through their effects on the number of breeding individuals of each sex, the mean number of progeny per female, and the variance in the number of progeny produced by males and females. Additionally, hierarchical structuring in a population is determined by the number of breeding groups and the migration rates of males and females among such groups. This study derives analytical solutions for effective sizes that can be applied to subdivided populations. Parameters that encapsulate breeding structure and subdivision are utilized to derive the traditional inbreeding and variance effective sizes. Also, it is shown that effective sizes can be determined for any hierarchical level of population structure for which gene correlations can accrue. Derivations of effective sizes for the accumulation of gene correlations within breeding groups (coancestral effective size) and among breeding groups (intergroup effective size) are given. The results converge to traditional, single population measures when similar assumptions are applied. In particular, inbreeding and intergroup effective sizes are shown to be special cases of the coancestral effective size, and intergroup and variance effective sizes will be equal if the population census remains constant. Instantaneous solutions for effective sizes, at any time after gene correlation begins to accrue, are given in terms of traditional F statistics or transition equations. All effective sizes are shown to converge upon a common asymptotic value when breeding tactics and migration rates are constant. The asymptotic effective size can be expressed in terms of the fixation indices and the number of breeding groups; however, the rate of approach to the asymptote is dependent upon dispersal

  16. Effect of texture on the cold rolling behavior of an alpha-two titanium aluminide

    SciTech Connect

    Sukonnik, I.M.; Semiatin, S.L.; Haynes, M. USAF, Wright Laboratory, Wright-Patterson AFB, OH Rensselaer Polytechnic Institute, Troy, NY )

    1992-03-01

    The effect of the texture on the cold rolling behavior of an alpha-2 titanium aluminide, Ti-14AL-21Nb (wt pct), was investigated by measuring pole figures, Knoop hardness yield loci, tensile ductility, and the starting microstructure of a number of lots of the cold-rolled material. Results showed that measurements of tensile ductility do not necessarily correlate with the cold rolling performance. On the other hand, the Knoop hardness yield locus provides a convenient quality control tool to assess lot-to-lot variations in texture and plastic anisotropy, and hence to estimate the rollability of sheet and foil specimens. 8 refs.

  17. Effect of Packaging and Antioxidant Combinations on Physicochemical Properties of Irradiated Restructured Chicken Rolls

    PubMed Central

    Yim, Dong-Gyun; Ahn, Dong U.

    2015-01-01

    Effects of double packaging (combinational use of aerobic and vacuum conditions) and antioxidants on physicochemical properties in irradiated restructured chicken rolls were determined. Chicken breast treated with antioxidants (none, sesamol+a-tocopherol) was used to process restructured chicken breast rolls. The sliced rolls were vacuum, aerobic, or double packaged (vacuum for 7 d then aerobic for 3 d) and electron beam irradiated at 2.5 kGy. Color, 2-thiobarbituric acid reactive substances (TBARS), oxidation reduction potentials (ORP), and volatile profiles of the samples were determined at 0 and 10 d. Irradiation made restructured chicken rolls redder (p<0.05), and the increased redness was more distinct in irradiated vacuum-packaged than irradiated aerobic or double packaged meats. TBARS values of antioxidant-treated double packaged rolls were lower than even nonirradiated vacuum-packaged meat, and those were distinct at 10 d (p<0.05). ORP and lipid oxidation values were lower in irradiated vacuum and double packaged samples than those in irradiated aerobic packaged ones at 0 d (p<0.05). Irradiation of restructured chicken rolls increased the amount of total volatiles. Considerable amounts of off-odor volatiles were reduced or not detected by double packaging and antioxidant treatment at 10 d. Therefore, the combined use of antioxidants and double packaging would be useful to reduce redness and control the oxidative quality changes of irradiated restructured chicken rolls. PMID:26761835

  18. The Effect of Long-Time Austenization on the Wear Resistance and Thermal Fatigue Properties of a High-Speed Steel Roll

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaodan; Liu, Wei; Godfrey, Andrew; Liu, Qing

    2009-09-01

    The effects of a long-time austenization treatment on a high-speed steel (HSS) roll have been investigated. Several interesting phenomena were observed, including the decomposition of the primary bulky M3C carbides on grain boundaries and the precipitation of a large number of MC carbides of size comparable to the primary MC carbides in the grains. As a consequence of these changes, the overall carbide size decreased and the homogeneity of the carbide distribution increased. The wear resistance and thermal fatigue properties of the HSS roll were also investigated, and it was found that the long-time austenization treatment resulted in improvements to both properties.

  19. Effect of composition and physical properties of silicon nitride on rolling wear and fatigue performance

    NASA Astrophysics Data System (ADS)

    Allen, Deborah L.

    1994-04-01

    The improved performance of silicon nitride components over all-steel bearings in several applications has been demonstrated. However, the effects of grain size, intergranular phase composition, fracture toughness, and hardness on rolling wear and fatigue performance are not completely understood. Three commercial bearing materials were tested under standard conditions and their physical properties were obtained. Wear and fatigue properties were compared to physical properties and material composition. It was found that a high fracture toughness is not required for high fatigue life and wear resistance. Total wear and fatigue life of the assembly must be considered, in addition to performance of the ceramic material alone, for specific applications. Grain boundary composition did not appear to affect the wear mechanism of these hot-isostatically-pressed materials.

  20. The effect of rare earth elements on the texture and formability of asymmetrically rolled magnesium sheet

    SciTech Connect

    Alderman, Dr. Martyn; Cavin, Odis Burl; Davis, Dr. Bruce; Muralidharan, Govindarajan; Muth, Thomas R; Peter, William H; Randman, David; Watkins, Thomas R

    2011-01-01

    The lack of formability is a serious issue when considering magnesium alloys for various applications. Standard symmetric rolling introduces a strong basal texture that decreases the formability; however, asymmetric rolling has been put forward as a possible route to produce sheet with weaker texture and greater ductility. It has also been shown in recent work that weaker textures can be produced through the addition of rare earth elements to magnesium alloys. Therefore, this study has been carried out to investigate the effect of rare earth additions on the texture changes during asymmetric rolling. Two alloys have been used, AZ31B and ZEK100. The effect that the rare earth additions have on the texture of asymmetrically rolled sheet and the subsequent changes in formability will be discussed.

  1. The Effect of Recrystallization on Interphase Precipitation in Hot-Rolled Steel Sheet

    NASA Astrophysics Data System (ADS)

    Bae, Cheoljun; Kim, Duhan; Kim, Jongryoul

    2017-07-01

    Hot-rolled steel products with high strength and good formability are in demand for automobile body parts, particularly steels which can reduce weight without sacrificing vehicle safety. Recent studies have suggested that interphase precipitation (IP) hardening is a promising approach for obtaining excellent high strength and superior formability from low-alloy steels. However, the effects of hot rolling conditions and alloying elements on IP hardening have not been clearly determined. In this study, we sought to clarify the above effects by analyzing the recrystallization behavior during hot rolling. As a result of sample testing and analysis, it was determined that the recrystallization which occurs during hot rolling plays a critical role in enhancing the IP hardening of low-alloy steels.

  2. Vibrations on the Roll - MANA, a Roll Along Array Experiment to map Local Site Effects Across a Fault System

    NASA Astrophysics Data System (ADS)

    Ohrnberger, M.; Scherbaum, F.; Hinzen, K. G.; Reamer, S. K.; Weber, B.

    2001-12-01

    The effects of surficial geology on seismic motion (site effects) are considered one of the major controlling factors to the damage distribution during earthquakes. Qualitative and quantitative estimates of local site amplifications provide important information for the identification of potential high risk areas. In this context, the analysis of ambient vibrations is an attractive tool for the mapping of site conditions. It is a low-cost alternative to expensive active seismic experiments or geophysical well-logging and especially well suited for the use within urban areas. Within the MANA experiment we conducted ambient vibration measurements at roughly 100 sites in the Lower Rhine Embayment (NW-Germany) to test various aspects of site effect determination, especially the feasibility of a roll along technique. A total of 13 three-component seismometers (5s corner period) have been used in a linear array configuration (station distance ~100 m). At all times during the roll-along experiment at least 8 stations (mostly 10) were operating simultaneously, meanwhilst the other stations were moved from the rear to the front of the line and re-installed. Thus, a total progress of almost 10 km could be obtained within two days. The line stretched across the NW-SE striking Erft fault system, one of the major faults in the eastern part of the Lower Rhine Embayment. The thickness of cenozoic soft-sediments overlying the basement of paleozoic age increases at the individual branches of the fault in abrupt steps of uncertain magnitude from around 200 m in the east to almost 1000 m in the west. The results of single station horizontal to vertical spectral ratios (HVSR) along the line are presented as well as the spatial evolution of local dispersion curves obtained from a slantstack analysis (SSA). The spatial variation of features along the line in both the HVSR and SSA are discussed in terms of sedimentary thickness and modifications of the wavefield properties of the ambient

  3. Aileron roll hysteresis effects on entry of space shuttle orbiter

    NASA Technical Reports Server (NTRS)

    Powell, R. W.

    1977-01-01

    Six-degree-of-freedom simulations of the space shuttle orbiter entry with control hysteresis were conducted on the NASA Langley Research Center interactive simulator known as the automatic reentry flight dynamics simulator. These simulations revealed that the vehicle can tolerate control hysteresis producing a + or - 50 percent change in the nominal aileron roll characteristics and an offset in the nominal characteristics equivalent to a + or - 5 deg aileron deflection with little increase in the reaction control system's fuel consumption.

  4. Effects of Casting Conditions on End Product Defects in Direct Chill Casted Hot Rolling Ingots

    NASA Astrophysics Data System (ADS)

    Yorulmaz, Arda; Yüksel, Çağlar; Erzi, Eraz; Dispinar, Derya

    Direct chill casting is a reliable casting process for almost any wrought aluminum alloy for subsequent deformation via hot rolling to supply vital industries such as aerospace, automotive, construction, packaging and maritime. While some defects occur during casting, like hot tearing, some others like surface defect causing blisters, appear after hot rolling process or annealing after final cold rolling steps. It was found that some of these defects are caused by melt impurities formed from entrained folded aluminum oxides or bifilms. A study in a hot rolling casting facility was carried out with different melt cleaning practices, launder and molten metal transferring designs. Bifilm index and reduced pressure test were used for determining melt cleanliness measurement. It was found that porous plug gas diffusons for degassing are more effective than lance type degassers and a design towards less turbulent molten metal flow from furnace to mould cavity are necessary for reducing defects caused by bifilms.

  5. Experimental and Numerical Study on the Effect of ZDDP Films on Sticking During Hot Rolling of Ferritic Stainless Steel Strip

    NASA Astrophysics Data System (ADS)

    Hao, Liang; Jiang, Zhengyi; Wei, Dongbin; Gong, Dianyao; Cheng, Xiawei; Zhao, Jingwei; Luo, Suzhen; Jiang, Laizhu

    2016-10-01

    The aim of this study is to investigate the effect of zinc dialkyl dithio phosphate (ZDDP) films on sticking during hot rolling of a ferritic stainless steel strip. The surface characterization and crack propagation of the oxide scale are very important for understanding the mechanism of the sticking. The high-temperature oxidation of one typical ferritic stainless was conducted at 1373 K (1100 °C) for understanding its microstructure and surface morphology. Hot-rolling tests of a ferritic stainless steel strip show that no obvious cracks among the oxide scale were observed with the application of ZDDP. A finite element method model was constructed with taking into consideration different crack size ratios among the oxide scale, surface profile, and ZDDP films. The simulation results show that the width of the crack tends to be reduced with the introduction of ZDDP films, which is beneficial for improving sticking.

  6. Investigation of interactions between limb-manipulator dynamics and effective vehicle roll control characteristics

    NASA Technical Reports Server (NTRS)

    Johnston, D. E.; Mcruer, D. T.

    1986-01-01

    A fixed-base simulation was performed to identify and quantify interactions between the pilot's hand/arm neuromuscular subsystem and such features of typical modern fighter aircraft roll rate command control system mechanization as: (1) force sensing side-stick type manipulator; (2) vehicle effective role time constant; and (3) flight control system effective time delay. The simulation results provide insight to high frequency pilot induced oscillations (PIO) (roll ratchet), low frequency PIO, and roll-to-right control and handling problems previously observed in experimental and production fly-by-wire control systems. The simulation configurations encompass and/or duplicate actual flight situations, reproduce control problems observed in flight, and validate the concept that the high frequency nuisance mode known as roll ratchet derives primarily from the pilot's neuromuscular subsystem. The simulations show that force-sensing side-stick manipulator force/displacement/command gradients, command prefilters, and flight control system time delays need to be carefully adjusted to minimize neuromuscular mode amplitude peaking (roll ratchet tendency) without restricting roll control bandwidth (with resulting sluggish or PIO prone control).

  7. Effect of Rolling Temperature and Ultrafast Cooling Rate on Microstructure and Mechanical Properties of Steel Plate

    NASA Astrophysics Data System (ADS)

    Ye, Qibin; Liu, Zhenyu; Yang, Yu; Wang, Guodong

    2016-07-01

    Microstructure can vary significantly through thickness after ultrafast cooling of rolled steel plates, impacting their mechanical properties. This study examined the microstructure, microstructural banding at centerline, and mechanical properties through thickness for different ultrafast cooling conditions and rolling temperatures. One set of steels (UC1 and UC2) were ultrafast-cooled (UFC) at 40 K/s after finish rolling at 1223 K and 1193 K (950 °C and 910 °C), respectively, while the second set (LC) was cooled by laminar cooling at 17 K/s after finish rolling at 1238 K (965 °C). UFC produced microstructural variation through thickness; highly dislocated lath-type bainitic ferrite was formed near the surface, whereas the primary microstructure was acicular ferrite and irregular polygonal ferrite in the interior of UC1 and UC2 steels, respectively. However, UFC has the advantage of suppression of microstructural banding in centerline segregation regions. The ferrite grain size in both UFC-cooled steels was refined to ~5 μm, increasing strength and toughness. The optimum combination of properties was obtained in UC2 steel with appropriate low finish rolling temperature, being attributed to the distinct microstructure resulting from work-hardened austenite before UFC.

  8. Size effect in thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Mao, Jun; Liu, Zihang; Ren, Zhifeng

    2016-12-01

    Thermoelectric applications have attracted increasing interest recently due to its capability of converting waste heat into electricity without hazardous emissions. Materials with enhanced thermoelectric performance have been reported in recent two decades. The revival of research for thermoelectric materials began in early 1990s when the size effect is considered. Low-dimensional materials with exceptionally high thermoelectric figure of merit (ZT) have been presented, which broke the limit of ZT around unity. The idea of size effect in thermoelectric materials even inspired the later nanostructuring and band engineering strategies, which effectively enhanced the thermoelectric performance of bulk materials. In this overview, the size effect in low-dimensional thermoelectric materials is reviewed. We first discuss the quantum confinement effect on carriers, including the enhancement of electronic density of states, semimetal to semiconductor transition and carrier pocket engineering. Then, the effect of assumptions on theoretical calculations is presented. Finally, the effect of phonon confinement and interface scattering on lattice thermal conductivity is discussed.

  9. Effects of hot-rolling reduction on microstructure, texture and magnetic properties of high silicon steel produced by strip casting

    NASA Astrophysics Data System (ADS)

    Hou, D. Y.; Xu, H. J.; Jiao, H. T.; Zhao, C. W.; Xiong, W.; Yang, J. P.; Qiu, W. Z.; Xu, Y. B.

    2017-01-01

    Non-oriented Fe-7.1wt.% Si as-cast strips were produced by twin-roll strip casting process. Then the as-cast strips were hot rolled with different reductions, followed by warm rolling and final annealing. The microstructure, texture evolution and magnetic properties were investigated in detail. The texture of hot rolled sheets with 40% reduction showed strongest {001}<110> texture, whereas the dominated texture was turned into {110}<001> and {110}<112>as the reduction was increased to 56% and 68%. After warm rolling and annealing, the average grain size was decreased firstly and then increased with an increase in hot rolling reduction. In the case of 40% hot rolling reduction, the recrystallization texture was dominated by strong γ (<111>//ND) texture. With an increase in hot rolling reduction, the γ texture was gradually weakened while α (<110>//RD) texture was enhanced. In addition, relatively stronger {100} texture was presented in the sheet of 68% hot rolling reduction. The highest B50 value attained was 1.66 T and the lowest P10/400 was 24.26 W/kg at a reduction of 56%.

  10. Effect Size in Clinical Phonology

    ERIC Educational Resources Information Center

    Gierut, Judith A.; Morrisette, Michele L.

    2011-01-01

    The purpose of this article is to motivate the use of effect size (ES) for single-subject research in clinical phonology, with an eye towards meta-analyses of treatment effects for children with phonological disorders. Standard mean difference (SMD) is introduced and illustrated as one ES well suited to the multiple baseline (MBL) design and…

  11. Effect Size in Clinical Phonology

    ERIC Educational Resources Information Center

    Gierut, Judith A.; Morrisette, Michele L.

    2011-01-01

    The purpose of this article is to motivate the use of effect size (ES) for single-subject research in clinical phonology, with an eye towards meta-analyses of treatment effects for children with phonological disorders. Standard mean difference (SMD) is introduced and illustrated as one ES well suited to the multiple baseline (MBL) design and…

  12. The cut-groove technique to infer interfacial effects during hot rolling

    NASA Astrophysics Data System (ADS)

    Das, S.; Palmiere, E. J.; Howard, Immpetus I. C.

    2004-03-01

    This article presents a novel experimental technique to infer the coupled effects of friction and heat transfer during the hot rolling of steels. The technique, termed the “cut-groove” method, relates the behavior of the deforming grooves cut on the strip surface to the local effects of friction and heat transfer. Validation of the experimentally observed groove shapes involved developing two-dimensional (2-D) and three-dimensional (3-D) finite-element (FE) models that employed a probabilistic distribution diagram (PDD). The PDD framework modeled the roll-strip interface and accounted for the variations in the oxide scale as distinct states that affect both friction and heat transfer. The numerically predicted groove openings are in good agreement with the experimentally observed groove shapes, particularly for the 2-D case. For the 3-D model, deviations are observed at regions close to the strip edges that are affected by nonplanar strain arising from spread during laboratory rolling.

  13. Effect of superconducting solenoid model cores on spanwise iron magnet roll control

    NASA Technical Reports Server (NTRS)

    Britcher, C. P.

    1985-01-01

    Compared with conventional ferromagnetic fuselage cores, superconducting solenoid cores appear to offer significant reductions in the projected cost of a large wind tunnel magnetic suspension and balance system. The provision of sufficient magnetic roll torque capability has been a long-standing problem with all magnetic suspension and balance systems; and the spanwise iron magnet scheme appears to be the most powerful system available. This scheme utilizes iron cores which are installed in the wings of the model. It was anticipated that the magnetization of these cores, and hence the roll torque generated, would be affected by the powerful external magnetic field of the superconducting solenoid. A preliminary study has been made of the effect of the superconducting solenoid fuselage model core concept on the spanwise iron magnet roll torque generation schemes. Computed data for one representative configuration indicate that reductions in available roll torque occur over a range of applied magnetic field levels. These results indicate that a 30-percent increase in roll electromagnet capacity over that previously determined will be required for a representative 8-foot wind tunnel magnetic suspension and balance system design.

  14. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Effect of Rolling Massage on Particle Moving Behaviour in Blood Vessels

    NASA Astrophysics Data System (ADS)

    Yi, Hou-Hui; Fan, Li-Juan; Yang, Xiao-Feng; Chen, Yan-Yan

    2008-09-01

    The rolling massage manipulation is a classic Chinese massage, which is expected to eliminate many diseases. Here the effect of the rolling massage on the particle moving property in the blood vessels under the rolling massage manipulation is studied by the lattice Boltzmann simulation. The simulation results show that the particle moving behaviour depends on the rolling velocity, the distance between particle position and rolling position. The average values, including particle translational velocity and angular velocity, increase as the rolling velocity increases almost linearly. The result is helpful to understand the mechanism of the massage and develop the rolling techniques.

  15. Effect of sliding and rolling friction on the energy-force parameters during hot rolling in four-high stands

    NASA Astrophysics Data System (ADS)

    Garber, E. A.; Kozhevnikova, I. A.; Tarasov, P. A.; Traino, A. I.

    2007-12-01

    A procedure for the calculation of the main-drive power for a hot-rolling wide-strip mill is developed. It takes into account that 85 99% of the lengths of the deformation zones in the working stands of such mills are occupied by stick zones, in which a strip undergoes static friction stresses (which do useful work only in the backward slip zone). This procedure also takes into account the rolling friction energy losses, which account for 83 93% of the power consumed for the rotation of idle backup rolls or 29 68% of the total energy consumed by the main mill drive. The average power calculation error for this procedure is 5%, and the maximum error is 10%, which is three to five times smaller than the errors of well-known calculation procedures. Our procedure has a high potential for revealing the reserves of decreasing the contact stresses in rolls and the saving of electric power via the redistribution of the reductions and tensions between stands and an increase in the temperature of the semi-finished rolled products.

  16. Effect of carbide distribution on rolling-element fatigue life of AMS 5749

    NASA Technical Reports Server (NTRS)

    Parker, R. J.; Bamberger, E. N.

    1983-01-01

    Endurance tests with ball bearings made of corrosion resistant bearing steel which resulted in fatigue lives much lower than were predicted are discussed. Metallurgical analysis revealed an undesirable carbide distribution in the races. It was shown in accelerated fatigue tests in the RC rig that large, banded carbides can reduce rolling element fatigue life by a factor of approximately four. The early spalling failures on the bearing raceways are attributed to the large carbide size and banded distribution.

  17. Models for the Effects of G-seat Cuing on Roll-axis Tracking Performance

    NASA Technical Reports Server (NTRS)

    Levison, W. H.; Mcmillan, G. R.; Martin, E. A.

    1984-01-01

    Including whole-body motion in a flight simulator improves performance for a variety of tasks requiring a pilot to compensate for the effects of unexpected disturbances. A possible mechanism for this improvement is that whole-body motion provides high derivative vehicle state information whic allows the pilot to generate more lead in responding to the external disturbances. During development of motion simulating algorithms for an advanced g-cuing system it was discovered that an algorithm based on aircraft roll acceleration producted little or no performance improvement. On the other hand, algorithms based on roll position or roll velocity produced performance equivalent to whole-body motion. The analysis and modeling conducted at both the sensory system and manual control performance levels to explain the above results are described.

  18. Effect of tangential traction and roughness on crack initiation/propagation during rolling contact

    NASA Technical Reports Server (NTRS)

    Soda, N.; Yamamoto, T.

    1980-01-01

    Rolling fatigue tests of 0.45 percent carbon steel rollers were carried out using a four roller type rolling contact fatigue tester. Tangential traction and surface roughness of the harder mating rollers were varied and their effect was studied. The results indicate that the fatigue life decreases when fraction is applied in the same direction as that of rolling. When the direction of fraction is reversed, the life increases over that obtained with zero traction. The roughness of harder mating roller also has a marked influence on life. The smoother the mating roller, the longer the life. Microscopic observation of specimens revealed that the initiation of cracks during the early stages of life is more strongly influenced by the surface roughness, while the propagation of these cracks in the latter stages is affected mainly by the tangential traction.

  19. Roll tracking effects of G-vector tilt and various types of motion washout

    NASA Technical Reports Server (NTRS)

    Jex, H. R.; Magdaleno, R. E.; Junker, A. M.

    1978-01-01

    In a dogfight scenario, the task was to follow the target's roll angle while suppressing gust disturbances. All subjects adopted the same behavioral strategies in following the target while suppressing the gusts, and the MFP-fitted math model response was generally within one data symbol width. The results include the following: (1) comparisons of full roll motion (both with and without the spurious gravity tilt cue) with the static case. These motion cues help suppress disturbances with little net effect on the visual performance. Tilt cues were clearly used by the pilots but gave only small improvement in tracking errors. (2) The optimum washout (in terms of performance close to real world, similar behavioral parameters, significant motion attenuation (60 percent), and acceptable motion fidelity) was the combined attenuation and first-order washout. (3) Various trends in parameters across the motion conditions were apparent, and are discussed with respect to a comprehensive model for predicting adaptation to various roll motion cues.

  20. Annealing Effects in Twin-Roll Cast AA8006 Aluminium Sheets Processed by Accumulative Roll-Bonding

    PubMed Central

    Cieslar, Miroslav; Poková, Michaela

    2014-01-01

    Ultrafine grained sheets were prepared from a twin-roll cast AA8006 aluminium alloy using accumulative roll-bonding process at room temperature. The evolution of microstructure of sheets after three accumulative roll-bonding passes during isochronal annealing with a constant step of 20 °C/20 min was studied by light and electron microscopy. The influence of the resulting microstructure on mechanical properties was monitored by microhardness measurements. The microhardness increases when the material is annealed up to 160 °C. Above this temperature a fast drop of microhardness occurs followed by a negligible variation at annealing temperatures exceeding 300 °C. In order to map continuously the microstructure changes during annealing, the in situ TEM experiments in the heating stage were performed as a supplement to post-mortem TEM observations. PMID:28788290

  1. Annealing Effects in Twin-Roll Cast AA8006 Aluminium Sheets Processed by Accumulative Roll-Bonding.

    PubMed

    Cieslar, Miroslav; Poková, Michaela

    2014-12-15

    Ultrafine grained sheets were prepared from a twin-roll cast AA8006 aluminium alloy using accumulative roll-bonding process at room temperature. The evolution of microstructure of sheets after three accumulative roll-bonding passes during isochronal annealing with a constant step of 20 °C/20 min was studied by light and electron microscopy. The influence of the resulting microstructure on mechanical properties was monitored by microhardness measurements. The microhardness increases when the material is annealed up to 160 °C. Above this temperature a fast drop of microhardness occurs followed by a negligible variation at annealing temperatures exceeding 300 °C. In order to map continuously the microstructure changes during annealing, the in situ TEM experiments in the heating stage were performed as a supplement to post-mortem TEM observations.

  2. Effect size in clinical phonology.

    PubMed

    Gierut, Judith A; Morrisette, Michele L

    2011-11-01

    The purpose of this article is to motivate the use of effect size (ES) for single-subject research in clinical phonology, with an eye towards meta-analyses of treatment effects for children with phonological disorders. Standard mean difference (SMD) is introduced and illustrated as one ES well suited to the multiple baseline (MBL) design and evaluation of generalization learning, both of which are key to experimental studies in clinical phonology.

  3. Effect size in clinical phonology

    PubMed Central

    Gierut, Judith A.; Morrisette, Michele L.

    2012-01-01

    The purpose of this article is to motivate the use of effect size (ES) for single-subject research in clinical phonology, with an eye towards meta-analyses of treatment effects for children with phonological disorders. Standard mean difference (SMD) is introduced and illustrated as one ES well suited to the multiple baseline (MBL) design and evaluation of generalization learning, both of which are key to experimental studies in clinical phonology. PMID:21787149

  4. The effect of rolling resistance on stationary wheelchair wheelies.

    PubMed

    Koshi, Edvin B; Kirby, R Lee; MacLeod, Donald A; Kozey, John W; Thompson, Kara J; Parker, Kim E

    2006-11-01

    To test the hypotheses that increased rolling resistance (RR) reduces rear-wheel displacement and perceived difficulty during the takeoff and balance phases of stationary wheelchair wheelies. We carried out within-subject comparisons of 20 participants as they each performed, in random order, two 30-sec stationary wheelies in three RR settings (tile, 5-cm-thick foam, and 12.5-cm-high blocks in front of and behind the rear wheels). The main outcome measures were rear-wheel displacement (in centimeters for the takeoff phase and centimeters per second for the balance phase) from a spring-loaded potentiometer and Likert scales of perceived difficulty. For rear-wheel displacement, all six of the pairwise comparisons (three terrains x two phases (takeoff and balance)) showed a significant statistical difference (P < 0.002). In each of the six pairwise comparisons, displacement was less for the higher of the two RR conditions. For perceived difficulty, during the balance phase, participants perceived tile to be significantly more difficult than either foam (P = 0.0067) or blocks (P = 0.0002). The other pairwise comparisons were not statistically significant. In conditions of increased RR, rear-wheel displacement and perceived difficulty are reduced during stationary wheelchair wheelies. These findings have implications for teaching wheelchair users to perform wheelies, a foundation of many advanced wheelchair skills.

  5. Effect of Fillet Rolling Load on the Fatigue Performance of a Micro-Alloy Steel Diesel Engine Crankshaft

    NASA Astrophysics Data System (ADS)

    Çevik, Gül; Gürbüz, Rıza

    2017-05-01

    Fillet rolling process is an effective method used to improve the fatigue performance of crankshafts by hardening the fillet region and inducing compressive residual stresses. This paper summarizes the work conducted to investigate the effect of rolling load on fatigue behaviour of a micro-alloy steel crankshaft used in diesel engine applications. Based on the staircase test methodology, component-scale resonant bending fatigue tests were conducted to obtain stress versus number of cycles curves and to evaluate the fatigue endurance limits of the crankshaft at un-rolled condition and fillet-rolled conditions at three different loads. Test data was analysed by Dixon-Mood method to calculate the endurance limits. Results showed that the endurance limit increased significantly with fillet rolling process in comparison to un-rolled condition. Endurance limit further increased with the increasing rolling load however with a limited extent above which excessive hardening deteriorates the fillet region; that is the workability limit. The outcomes of this study has shed light on the fillet rolling process to select the optimum rolling load for the used design and material conditions.

  6. Effect of Rolling on High-Cycle Fatigue and Fracture of an Al - Mg - Sc Alloy

    NASA Astrophysics Data System (ADS)

    Zhemchuzhnikova, D. A.; Petrov, A. P.; Eremeev, N. V.; Eremeev, V. V.; Kaibyshev, R. O.

    2016-07-01

    The tensile strength and fatigue properties of alloy 1575 of the Al - Mg - Sc system are studied after hot deformation (at 360°C) and subsequent cold rolling with different reduction ratios. The effect of the deformed structure on the properties and mechanisms of fracture of the alloy under cyclic tests is determined.

  7. Effects of gamma and electron beam irradiation on the microbial quality of steamed tofu rolls

    NASA Astrophysics Data System (ADS)

    Jia, Qian; Gao, Meixu; Li, Shurong; Wang, Zhidong

    2013-01-01

    The effectiveness of two kinds of radiation processing, gamma and electron beam (ebeam) irradiation, for the inactivation of Staphylococcus aureus, Salmonella enteritidis and Listeria innocua which were inoculated in pre-sterilised steamed tofu rolls was studied. The corresponding effects of both irradiation types on total bacterial counts (TBCs) in commercial steamed tofu rolls available in the market were also examined. The microbiological results demonstrated that gamma irradiation yielded D10 values of 0.20, 0.24 and 0.22 kGy for S. aureus, S. enteritidis and L. innocua, respectively. The respective D10 values for ebeam irradiation were 0.31, 0.35 and 0.27 kGy. Gamma and ebeam irradiation yielded D10 values of 0.48 and 0.43 kGy for total bacterial counts in commercial steamed tofu rolls, respectively. The results suggest that ebeam irradiation has similar effect on decreasing TBCs in steamed tofu rolls, and gamma irradiation is slightly more effective than ebeam irradiation in reducing the populations of pathogenic bacteria. The observed differences in D10-values between them might be due to the significant differences in dose rate applied, and radiation processing of soybean products to improve their microbial quality could be available for other sources of protein.

  8. Effects of multiple rolling cover crops on their termination, soil water and soil strength

    USDA-ARS?s Scientific Manuscript database

    The impact of multiple rolling rye and mixture (rye, crimson clover and hairy vetch) using two rollers (straight bar, and two-stage) on termination rate, soil strength and soil moisture were evaluated in northern Alabama. In 2007 and 2008 growing seasons, both roller types effectively terminated rye...

  9. Effects of cellulose fiber with different fiber length on rheological properties of wheat dough and quality of baked rolls.

    PubMed

    Lauková, Michaela; Kohajdová, Zlatica; Karovičová, Jolana; Kuchtová, Veronika; Minarovičová, Lucia; Tomášiková, Lenka

    2017-09-01

    Powdered cellulose is often used in cereal processing industry. The effects of partial replacement (0.5%, 1%, 2% and 5%) of wheat flour by cellulose fiber with different fiber length (80, 120 and 220 µm) on rheological properties of wheat dough and qualitative parameters of baked rolls were studied. Sensory evaluation of baked products was also performed. Mixing and pasting properties of dough were determined by Mixolab. Generally, cellulose-enriched dough was characterized with higher water absorption, dough stability and parameters C2 and C3. Moreover, it was found that parameters C4 and C5 increased with increasing cellulose fiber length. From the results, it was also concluded that the physical parameters of baked rolls containing cellulose were reduced. It was also observed that the incorporation of cellulose fiber with shorter fiber length concluded in lower rolls volume compared to cellulose fiber with long fiber length. Texture analyses showed that the firmness of rolls containing cellulose at the substitution level 5% was significantly higher than those of the control, whereas the springiness of wheat rolls was not significantly affected. It was also recorded that the firmness and cohesiveness of baked rolls were higher after the addition of cellulose fiber with shorter fiber length. Sensory evaluation indicated that baked rolls with cellulose addition up to 1% were comparable with control rolls. Results also showed that higher levels of cellulose significantly decreased crust, taste, color and porosity of rolls.

  10. Variation of effective roll number on MHD Rayleigh-Benard convection confined in a small-aspect ratio box

    NASA Astrophysics Data System (ADS)

    Tasaka, Yuji; Yanagisawa, Takatoshi; Vogt, Tobias; Eckert, Sven

    2015-11-01

    MHD Rayleigh-Benard convection was studied experimentally using a box filled with liquid metal with five in aspect ratio and square horizontal cross section. Applying horizontal magnetic field organizes the convection motion into quasi-two dimensional rolls arranged parallel to the magnetic field. The number of rolls has tendency, decreases with increasing Rayleigh number Ra and increases with increasing Chandrasekhar number Q. To fit the box with relatively smaller aspect ratio, the convection rolls take regime transition accompanying variation of the roll number against variations of Ra and Q. We explored convection regimes in a ranges, 2 ×103 < Q <104 and 5 ×103 < Ra < 3 ×105 using ultrasonic velocity profiling that can capture time variations of instantaneous velocity profile. In a range Ra / Q ~ 10 , we found periodic flow reversals in which five rolls periodically change the direction of their circulation with gradual skew of rolls. We performed POD analysis on the spatio-temporal velocity distribution obtained by UVP and indicated that that the periodic flow reversals consist of periodic emergence of 4-rolls mode in dominant 5-rolls mode. POD analysis also provided evaluation of effective number of rolls as a more objective approach.

  11. Modelling pressure rolling of asymmetric rolling process

    NASA Astrophysics Data System (ADS)

    Alexa, V.; Ratiu, S. A.; Kiss, I.; Cioata, V. G.

    2017-05-01

    The paper presents a comparative analysis between experimental results and modelling in order to interpret the value of the contact pressure on the asymmetric longitudinal rolling. It is also intended action and the different behaviour of upper cylinder compared to the lower cylinder action in situations when both are driven, or only one operates. In the modelling will be presented on the basis of boundary conditions imposed rolling pressure variation in the degree of reduction and also re size arc length of contact. Determining a curve is also important to determine the locus of points which characterize symmetry conditions partial rolling process between unequal diameters cylinders.

  12. SU-F-P-31: Dosimetric Effects of Roll and Pitch Corrections Using Robotic Table

    SciTech Connect

    Mamalui, M; Su, Z; Flampouri, S; Li, Z

    2016-06-15

    Purpose: To quantify the dosimetric effect of roll and pitch corrections being performed by two types of robotic tables available at our institution: BrainLabTM 5DOF robotic table installed at VERO (BrainLab&MHI) dedicated SBRT linear accelerator and 6DOF robotic couch by IBA Proton Therapy with QFixTM couch top. Methods: Planning study used a thorax phantom (CIRSTM), scanned at 4DCT protocol; targets (IGTV, PTV) were determined according to the institutional lung site-specific standards. 12 CT sets were generated with Pitch and Roll angles ranging from −4 to +4 degrees each. 2 table tops were placed onto the scans according to the modality-specific patient treatment workflows. The pitched/rolled CT sets were fused to the original CT scan and the verification treatment plans were generated (12 photon SBRT plans and 12 proton conventional fractionation lung plans). Then the CT sets were fused again to simulate the effect of patient roll/pitch corrections by the robotic table. DVH sets were evaluated for all cases. Results: The effect of not correcting the phantom position for roll/pitch in photon SBRT cases was reducing the target coverage by 2% as maximum; correcting the positional errors by robotic table varied the target coverage within 0.7%. in case of proton treatment, not correcting the phantom position led to the coverage loss up to 4%, applying the corrections using robotic table reduced the coverage variation to less than 2% for PTV and within 1% for IGTV. Conclusion: correcting the patient position by using robotic tables is highly preferable, despite the small dosimetric changes introduced by the devices.

  13. Effects of thermal treatment on the co-rolled U-Mo fuel foils

    SciTech Connect

    Dennis D. Keiser, Jr.; Tammy L. Trowbridge; Cynthia R. Breckenridge; Brady L. Mackowiak; Glenn A. Moore; Barry H. Rabin; Mitchell K. Meyer

    2014-11-01

    A monolithic fuel type is being developed to convert US high performance research and test reactors such as Advanced Test Reactor (ATR) at Idaho National Laboratory from highly enriched uranium (HEU) to low-enriched uranium (LEU). The interaction between the cladding and the U-Mo fuel meat during fuel fabrication and irradiation is known to have negative impacts on fuel performance, such as mechanical integrity and dimensional stability. In order to eliminate/minimize the direct interaction between cladding and fuel meat, a thin zirconium diffusion barrier was introduced between the cladding and U-Mo fuel meat through a co-rolling process. A complex interface between the zirconium and U-Mo was developed during the co-rolling process. A predictable interface between zirconium and U-Mo is critical to achieve good fuel performance since the interfaces can be the weakest link in the monolithic fuel system. A post co-rolling annealing treatment is expected to create a well-controlled interface between zirconium and U-Mo. A systematic study utilizing post co-rolling annealing treatment has been carried out. Based on microscopy results, the impacts of the annealing treatment on the interface between zirconium and U-Mo will be presented and an optima annealing treatment schedule will be suggested. The effects of the annealing treatment on the fuel performance will also be discussed.

  14. Effect of lubricant extreme pressure additives on rolling element fatigue life

    NASA Technical Reports Server (NTRS)

    Parker, R. J.; Zaretsky, E. V.

    1973-01-01

    The effects of surface active additives on rolling-element fatigue life were investigated with the five-ball fatigue tester at conditions where classical subsurface initiated rolling-element fatigue is the sole mode of failure. Test balls of AISI 52100, AISI M-50, and AISI 1018 were run with an acid-treated white oil containing either 2.5 percent sulfurized terpene, 1 percent didodecyl phosphite, or 5 percent chlorinated wax. In general, it was found that the influence of surface active additives was detrimental to rolling-element fatigue life. The chlorinated-wax additive significantly reduced fatigue life by a factor of 7. The base oil with the 2.5 percent sulfurized-terpene additive can reduce fatigue life by as much as 50 percent. No statistical change in fatigue life occurred with the base oil having the 1 percent didodecyl-phosphite additive. The additives used with the base oil did not change the ranking of the bearing steels where rolling-element fatigue life was of subsurface origin.

  15. Effect of rolling resistance on poling forces and metabolic demands of roller skiing.

    PubMed

    Millet, G Y; Hoffman, M D; Candau, R B; Buckwalter, J B; Clifford, P S

    1998-05-01

    To examine the effect of an increase in roller ski rolling resistance on the physiological and upper body demands of roller skiing with the V2-alternate technique. Nine highly skilled cross-country skiers roller skied at three paced speeds on a flat oval loop using roller skis with high (HiR) and low (LowR) rolling resistance. Oxygen uptake (VO2), heart rate, and poling forces were measured during the last 30 s and rating of perceived exertion (RPE) was requested immediately after each 4-min bout of roller skiing. VO2 and all force-related variables increased significantly with speed and were higher (P < 0.01) for HiR at given speeds. Poling time was similar between HiR and LowR, whereas poling recovery time was shorter (P = 0.0002) and cycle rate was higher (P = 0.002) for HiR. For given VO2 levels, peak and average forces, heart rates, and RPE values were similar between HiR and LowR, whereas average poling force across the cycle was greater (P = 0.006) and duty cycle (i.e., percentage of cycle when poling forces were applied) was higher (P = 0.0001) with HiR. 1) The decrease in poling recovery time and increase in cycle rate associated with an increase in roller ski rolling resistance is comparable to the effect previously observed from increasing grade and probably occurs as a means of limiting deceleration. 2) Since changes in rolling resistance do not alter the relationships of RPE and heart rate with VO2, the central cardiovascular adaptations from roller ski training should not be affected by the rolling resistance of the roller skis. 3) Higher resistance roller skis are likely to induce greater upper body aerobic adaptations than lower resistance roller skis.

  16. Effect of rolling motion on local characteristics of gas-liquid two-phase flow using an optical probe

    NASA Astrophysics Data System (ADS)

    Tian, Daogui; Sun, Licheng; Yan, Changqi; Liu, Jingyu; Sun, Bo

    2013-07-01

    In order to get more local interfacial information as well as to further comprehend the intrinsic mechanism of two-phase flow under rolling condition to improve and extend the two-fluid model in rolling condition, an experimental investigation of two-phase flow under rolling as well as vertical steady condition was conducted by using double-sensor optical probe fabricated by the authors. The experimental loop is fixed on a rolling platform, which can simulate the rolling movement of a ship with the rolling period and rolling angle in the ranges of 0-20s and 0-45°, respectively. An optical probe driven by a mechanical traverser is installed on the test section, wherein making it move diametrically. Experimental investigations were conducted on this experimental loop for air-water two-phase flow under rolling and steady conditions. Local void fraction, interfacial area concentration (IAC) and bubble velocity were obtained for further improving the interface transportation equation. Both the measured void fraction and IAC demonstrated wall peak or core peak distributions under vertical condition. The typical distribution of IAC under vertical conditions showed that IAC changes from wall peak to core peak with the gas flow rate increasing; while as the liquid flow rate increases, the distribution changes inversely. In the case of rolling conditions, despite similar to the distribution under vertical condition, the local time-averaged void fraction and IAC have lower value in centerline and high value near wall region. The results also indicated that the rolling amplitude has an influence on the local bubble frequency, void fraction and IAC, except interface velocity, while rolling period almost has no effect on the local characteristics.

  17. Recalibrated Equations for Determining Effect of Oil Filtration on Rolling Bearing Life

    NASA Technical Reports Server (NTRS)

    Needelman, William M.; Zaretsky, Erwin V.

    2014-01-01

    In 1991, Needelman and Zaretsky presented a set of empirically derived equations for bearing fatigue life (adjustment) factors (LFs) as a function of oil filter ratings. These equations for life factors were incorporated into the reference book, "STLE Life Factors for Rolling Bearings." These equations were normalized (LF = 1) to a 10-micrometer filter rating at Beta(sub x) = 200 (normal cleanliness) as it was then defined. Over the past 20 years, these life factors based on oil filtration have been used in conjunction with ANSI/ABMA standards and bearing computer codes to predict rolling bearing life. Also, additional experimental studies have been made by other investigators into the relationship between rolling bearing life and the size, number, and type of particle contamination. During this time period filter ratings have also been revised and improved, and they now use particle counting calibrated to a new National Institute of Standards and Technology (NIST) reference material, NIST SRM 2806, 1997. This paper reviews the relevant bearing life studies and describes the new filter ratings. New filter ratings, Beta(sub x(c)) = 200 and Beta(sub x(c)) = 1000, are benchmarked to old filter ratings, Beta(sub x) = 200, and vice versa. Two separate sets of filter LF values were derived based on the new filter ratings for roller bearings and ball bearings, respectively. Filter LFs can be calculated for the new filter ratings.

  18. Effect of rolling on the high temperature tensile and stress-rupture properties of tungsten fiber-superalloy composites

    NASA Technical Reports Server (NTRS)

    Petrasek, D. W.

    1974-01-01

    An investigation was conducted to determine the effects of mechanical working on the 1093 C (2000 F) tensile and stress-rupture strength of tungsten alloy/superalloy composites. Hot pressed composites containing either conventional tungsten lamp filament wire or tungsten-1% ThO2 wire and a nickel base alloy matrix were hot rolled at 1093 C (2000 F). The hot pressed and rolled composite specimens were then tested in tension and stress-rupture at 1093 C (2000 F). Rolling decreased the degree of fiber-matrix reaction as a function of time of exposure at 1093 C (2000 F). The stress-rupture properties of the rolled composites were superior to hot pressed composites containing equivalent diameter fibers. Rolling did not appreciably affect the 1093 C (2000 F) ultimate tensile strength of the composites.

  19. Threshold voltage roll-off modelling of bilayer graphene field-effect transistors

    NASA Astrophysics Data System (ADS)

    Saeidmanesh, M.; Ismail, Razali; Khaledian, M.; Karimi, H.; Akbari, E.

    2013-12-01

    An analytical model is presented for threshold voltage roll-off of double gate bilayer graphene field-effect transistors. To this end, threshold voltage models of short- and long-channel states have been developed. In the short-channel case, front and back gate potential distributions have been modelled and used. In addition, the tunnelling probability is modelled and its effect is taken into consideration in the potential distribution model. To evaluate the accuracy of the potential model, FlexPDE software is employed with proper boundary conditions and a good agreement is observed. Using the proposed models, the effect of several structural parameters on the threshold voltage and its roll-off are studied at room temperature.

  20. The effect of skatole and androstenone on consumer response towards streaky bacon and pork belly roll.

    PubMed

    Aaslyng, Margit D; De Lichtenberg Broge, Eva Honnens; Brockhoff, Per B; Christensen, Rune Haubo

    2015-12-01

    Consumer liking was assessed for streaky bacon and pork belly roll from entire male pigs with an androstenone (AND) content of up to 9.4 ppm and a skatole (SKA) content of up to 0.92 ppm in the back fat and castrates. No clear effect of either AND or SKA was seen in consumer liking, although an insignificant tendency was seen for SKA. A sensory profile analysis showed that AND increased the boar taint of bacon, while both AND and SKA increased the boar taint of the pork belly roll. Consumer sensitivity towards AND and SKA did not affect liking of the meat products. The lack of effect of AND and SKA on consumer liking could be due to a masking effect of the spices and smoke. Three consecutive weeks' exposure to bacon did not change the liking score, irrespective of the AND and SKA content. This indicates that the consumers did not become more sensitive towards boar taint.

  1. A Primer on Basic Effect Size Concepts.

    ERIC Educational Resources Information Center

    Elmore, Patricia B.; Rotou, Ourania

    The increased interest in reporting effect sizes means that it is necessary to consider what should be included in a primer on effect sizes. A review of papers on effect sizes and commonly repeated statistical analyses suggests that it is important to discuss effect sizes relative to bivariate correlation, t-tests, analysis of variance/covariance,…

  2. Physiological effects of technique and rolling resistance in uphill roller skiing.

    PubMed

    Hoffman, M D; Clifford, P S; Snyder, A C; O'Hagan, K P; Mittelstadt, S W; Roberts, M M; Drummond, H A; Gaskill, S E

    1998-02-01

    The double pole technique (DP) has been shown to be more economical than the V1 skate technique (V1 ) on flat terrain. The objective of the present study was to compare these two techniques during uphill roller skiing. In addition, the physiological effects of changing roller ski rolling resistance was examined for V1. Five female and five male competitive cross-country skiers roller skied 4-min bouts on a 5.2% incline while physiological measurements were made. Oxygen uptake (VO2) values averaged 8% greater (P = 0.0004) with V1, whereas rating of perceived exertion (RPE) and blood lactate concentrations were higher (P < or = 0.002) with DP. Doubling the dynamic friction coefficient of the roller skis, which increased external power output by 16-17%, resulted in VO2 values with V1 that averaged 13% higher (P = 0.0006). This magnitude of change in roller ski rolling resistance did not cause a statistical change in the relationship of VO2 with RPE. These findings suggest that 1) grade has little effect on relative economies of DP and V1, possibly because of a lower effectiveness of force application with V1 when going uphill, and 2) large differences in roller ski rolling resistance should have no effect on the cardiovascular training adaptations that result from uphill roller skiing with V1.

  3. Effect of Electric-current Pulses on Grain-structure Evolution in Cryogenically Rolled Copper

    DTIC Science & Technology

    2014-11-01

    components disappeared almost com- pletely [Figs. 8(a) and 9(a)]. Instead, the texture comprised mainly (55; 30/60; 0) and cube -RD com- ponents as well as...Microstructure region in Fig. 7 Peak intensity of ODF (X random) Volume fraction of main texture components (within 15° tolerance) (%) Brass Goss Cube -RD Cube ...ABSTRACT The effect of electric-current pulses on the evolution of microstructure and texture in cryogenically rolled copper was determined. The pulsed

  4. Effect of size on cracking of materials

    NASA Technical Reports Server (NTRS)

    Glucklick, J.

    1971-01-01

    Brittle behavior of large mild steel elements, glass plasticity, and fatigue specimen size sensitivity are manifestations of strain-energy size effect. Specimens physical size effect on material cracking initiation occurs according to flaw distribution statistics. Fracture size effect depends on stability or instability of crack propagation.

  5. Effects of intermittent pressure imitating rolling manipulation on calcium ion homeostasis in human skeletal muscle cells.

    PubMed

    Zhang, Hong; Liu, Howe; Lin, Qing; Zhang, Guohui; Mason, David C

    2016-08-26

    Homeostasis imbalance of intracellular Ca(2+) is one of the key pathophysiological factors in skeletal muscle injuries. Such imbalance can cause significant change in the metabolism of Ca(2+)-related biomarkers in skeletal muscle, such as superoxide dismutase (SOD), malondialdehyde (MDA) and creatine kinase (CK). Measurements of these biomarkers can be used to evaluate the degree of damage to human skeletal muscle cells (HSKMCs) injury. Rolling manipulation is the most popular myofascial release technique in Traditional Chinese Medicine. The mechanism of how this technique works in ameliorating muscle injury is unknown. This study aimed to investigate the possible Ca(2+) mediated effects of intermittent pressure imitating rolling manipulation (IPIRM) of Traditional Chinese Medicine in the injured HSKMCs. The normal HSKMCs was used as control normal group (CNG), while the injured HSKMCs were further divided into five different groups: control injured group (CIG), Rolling manipulation group (RMG), Rolling manipulation-Verapamil group (RMVG), static pressure group (SPG) and static pressure-Verapamil group (SPVG). RMG and RMVG cells were cyclically exposed to 9.5-12.5 N/cm(2) of IPIRM at a frequency of 1.0 Hz for 10 min. SPG and SPVG were loaded to a continuous pressure of 12.5 N/cm(2) for 10 min. Verapamil, a calcium antagonist, was added into the culture mediums of both RMVG and SPVG groups to block the influx of calcium ion. Compared with the CNG (normal cells), SOD activity was remarkably decreased while both MDA content and CK activity were significantly increased in the CIG (injured cells). When the injured cells were treated with the intermittent rolling manipulation pressure (RMG), the SOD activity was significantly increased and MDA content and CK activity were remarkably decreased. These effects were suppressed by adding the calcium antagonist Verapamil into the culture medium in RMVG. On the other hand, exposure to static pressure in SPG and SPVG

  6. Effect of Austenitizing Temperature on Microstructure and Mechanical Properties of Semi-High-Speed Steel Cold-Forged Rolls

    NASA Astrophysics Data System (ADS)

    Wu, Qiong; Sun, Da-Le; Liu, Chang-Sheng

    2009-10-01

    The effect of austenitizing temperature on the microstructure and mechanical properties of semi-high-speed steel (S-HSS) cold-forged rolls was investigated. Low-temperature austenitizing below 1313 K induced carbide coarsening during subsequent tempering at 973 K due to the nucleation effect of undissolved M7C3. On the other hand, the heavy dissolution of M7C3 above 1353 K caused the fine carbide formation on lath and plate boundaries, which retarded the subgrain growth during tempering. The increase in strength with increasing austenitizing temperature was attributed to the fine carbide distribution and the high dislocation density. Furthermore, as the austenitizing temperature increased, the impact energy markedly reduced, due to the large prior austenite grain size and the high strength. Finally, based on the microstructure and mechanical properties, an optimal austenitizing temperature range between 1313 and 1333 K was determined.

  7. The effect of manganese and sulfur contents on the magnetic properties of cold rolled lamination steels

    NASA Astrophysics Data System (ADS)

    Liao, K. C.

    1986-08-01

    The effect of Mn and S contents on the magnetic properties of cold rolled lamination steel was investigated in eleven low C steels. The results indicated that Mn content was a major factor influencing the magnetic quality of the lamination steels. An optimum range of Mn was a prerequisite for optimum permeability and exciting power. For Mn contents up to 1.25 Pct, the core loss improved nonlinearly with increasing Mn content. At higher Mn contents, the magnetic properties deteriorated for the experimental conditions used as a consequence of poor grain size development after the final decarburizing anneal. Decreasing the S content from 0.018 Pct to 0.010 Pct improved the core loss at all induction levels. The permeability and exciting power were improved at 1 T, but a very slight deterioration in permeability and exciting power was seen at 1.5 and 1.7 T. Estimations of core loss improvement based on regression equations indicated that lowering the S content from 0.018 Pct to 0.010 Pct improved the core loss in w/lb-mil as follows: 0.0041 at 1 T, 0.0079 at 1.5 T, and 0.0093 at 1.7 T (1 w/lb-mil = 86.8 w/kg-mm). The response surface analyses indicated that Mn content in the range of 0.7 Pct to 1 Pct, depending on the S content, should develop optimum magnetic properties. However, Mn content at the low end of this range is preferred for practical applications.

  8. Strain effect on intersubband transitions in rolled-up quantum well infrared photodetectors

    NASA Astrophysics Data System (ADS)

    Wang, Han; Li, Shilong; Zhen, Honglou; Nie, Xiaofei; Huang, Gaoshan; Mei, Yongfeng; Lu, Wei

    2017-06-01

    Pre-strained nanomembranes with four embedded quantum wells (QWs) are rolled up into three-dimensional (3D) tubular QW infrared photodetectors (QWIPs), which are based on the QW intersubband transition (ISBT). A redshift of ∼0.42 meV in photocurrent response spectra is observed and attributed to two strain contributions due to the rolling of the pre-strained nanomembranes. One is the overall strain that mainly leads to a redshift of ∼0.5 meV, and the other is the strain gradient which results in a very tiny variation. The blue shift of the photocurrent response spectra with the external bias are also observed as quantum-confined Stark effect (QCSE) in the ISBT. Project supported by the Natural Science Foundation of China (Nos. 51322201, 61575213), and the Shanghai Municipal Science and Technology Commission (No. 14JC1400200)

  9. Effect of inter-particle rolling resistance on passive earth pressure against a translating rigid retaining wall

    NASA Astrophysics Data System (ADS)

    Jiang, Mingjing; He, Jie; Liu, Fang; Wang, Huaning

    2013-06-01

    The presence of the inter-particle rolling resistance of soil grains results in higher bulk shear strength in the soil, which relates to the earth pressure calculation based on the classic theory. This paper focuses on the effect of the inter-particle rolling resistance on the earth pressure against a rigid retaining wall. A particle contact model considering the inter-particle rolling resistance was implemented into the distinct element code PFC2D, which was then used to simulate a rigid wall retaining a sandy backfill. The passive earth pressure against the wall subjected to a translational displacement was analyzed and compared with results without considering the inter-particle rolling resistance. The influence of the inter-particle rolling resistance was examined from the microscopic scale (e.g., averaged micro-pure rotation-rate) as well as the macroscopic scale (e.g., the magnitude and action point of resultant earth pressures). The results show that the inter-particle rolling resistance of the backfill strongly affects the value of passive thrust behind the wall, but it has no significant effect on the action position of the thrust. The distribution of micro-pure rotation-rate (APR) in the backfill provides an insight into the connection between inter-particle rolling resistance to the energy dissipation in the shear zone behind the wall.

  10. Effect of Controlled Hot Rolling Parameters on Microstructure of a Nb-Microalloyed Steel Sheet

    SciTech Connect

    Khaki, Daavood Mirahmadi; Abedi, Amir

    2011-01-17

    The design of controlled rolling process of microalloyed steel sheets is affected by several factors. In this investigation, effect of the reheating, finishing and coiling temperatures of rolling, which are considered as the most effective parameters on microstructure of hot rolled products has been studied. For this purpose, seven different reheating temperatures between 1000 to 1300 deg. C with 50 deg. C increments, three different finishing temperatures of 950, 900 and 850 deg. C below the non-recrystallization temperature and one temperature of 800 deg. C in the inter critical range and four different coiling temperatures of 550, 600, 650 and 700 deg. C were chosen. By soaking the specimens in furnace, the grain coarsening temperature (T{sub gc}) is obtained about 1250 deg. C. Hence, for these kinds of steels, the reheating temperature 1200 to 1250 deg. C is recommended. Moreover, it is observed that decreasing the coiling and finishing temperatures causes more grain refinement of microstructure and the morphology is changed from polygonal ferrite to acicular one. Findings of this research provide a good connection among reheating, finishing and coiling temperatures and microstructural features of Nb-microalloyed steel sheets.

  11. The Effect of Foam Rolling Duration on Hamstring Range of Motion

    PubMed Central

    Couture, Grace; Karlik, Dustin; Glass, Stephen C; Hatzel, Brian M

    2015-01-01

    Musculoskeletal health benefits from flexibility training and maintaining a functional, or sport specific, range of motion is important to one’s overall fitness. Commercial foam rollers are commonly used in gyms, therapy clinics and homes, yet data are lacking on the optimal rolling duration and effect on range of motion. Purpose : The purpose of this study was to examine the effect of varied durations of a commercial foam roller treatment on hamstring range of motion. Methods : The knee extension range of motion of 33 college aged men and women (age= 20±1.5y, mass= 72.2±10.8 kg) was assessed after a short (2 sets of 10s) and long (4 sets of 30s) duration of hamstring self-administered myofascial release using a commercial foam roller. A one way ANOVA was performed to compare the mean knee extension angle for each condition to baseline measures. Results : Results indicated that neither the short duration (67.30 ± 10.60 deg) nor long duration (67.41 ± 10.81 deg) rolling condition produced significant increases in knee extension compared to baseline (67.70 ± 9.90 deg). Conclusion : Self-administered foam rolling for a total duration of up to 2 minutes is not adequate to induce improvements in knee joint flexibility. Contributing factors may include the amount of pressure imparted by the commercial roller as well as duration of treatment. PMID:26587061

  12. Numerical study of strain-rate effect in cold rolls forming of steel

    NASA Astrophysics Data System (ADS)

    Falsafi, J.; Demirci, E.; Silberschmidt, V. V.

    2013-07-01

    Cold roll forming (CRF) is a well-known continuous manufacturing process, in which a flat strip is deformed by successive rotating pairs of tools, without changing the material thickness. In the past decades, to lessen the process-development efforts, finite-element simulations have been increasingly employed to improve the process design and predict the manufacturing-induced defects. One of the important aspects in design of the CRF process is consideration of resulting strains in the final product as the material passes through several complex forming stands. Sufficient knowledge of longitudinal strain in the workpiece is required to set various process parameters. Increasing a process speed in a roll forming operation can bring cost advantages, but the influence of the forming speed on the strain distribution should be explored. This study is focussed on a strain-rate effect in the CRF process of steel sheets. The strain-rate dependency of a plastic behaviour observed in most metals can affect the finished product's quality as well as process parameters. This paper investigates the influence of the strain rate on longitudinal strains induced in the roll forming operation by incorporating a phenomenological Johnson-Cook constitutive model, which allows studying the impact of the process speed on the output product. Taking advantage of 3D finite element analysis, a roll forming process was simulated using MCS.Marc, comprising a complete set of forming stations. Through the changing of the process speed, the strain rate impact on longitudinal peak strains and forming length was investigated. The results highlight the effect of the strain rate on edge thinning and subsequent undesirable distortions in the product.

  13. Analysis of Effect of Rolling Pull-Outs on Wing and Aileron Loads of a Fighter Airplane

    NASA Technical Reports Server (NTRS)

    Pearson, Henry A.; Aiken, William S.

    1946-01-01

    An analysis was made to determine the effect of rolling pull-out maneuvers on the wing and aileron loads of a typical fighter airplane, the P-47B. The results obtained indicate that higher loads are imposed upon wings and ailerons because of the rolling pull-out maneuver, than would be obtained by application of the loading requirements to which the airplane was designed. An increase of 102 lb or 15 percent of wing weight would be required if the wing were designed for rolling pull-out maneuver. It was also determined that the requirements by which the aileron was originally designed were inadequate.

  14. Class-Size Effects in Secondary School

    ERIC Educational Resources Information Center

    Krassel, Karl Fritjof; Heinesen, Eskil

    2014-01-01

    We analyze class-size effects on academic achievement in secondary school in Denmark exploiting an institutional setting where pupils cannot predict class size prior to enrollment, and where post-enrollment responses aimed at affecting realized class size are unlikely. We identify class-size effects combining a regression discontinuity design with…

  15. Class-Size Effects in Secondary School

    ERIC Educational Resources Information Center

    Krassel, Karl Fritjof; Heinesen, Eskil

    2014-01-01

    We analyze class-size effects on academic achievement in secondary school in Denmark exploiting an institutional setting where pupils cannot predict class size prior to enrollment, and where post-enrollment responses aimed at affecting realized class size are unlikely. We identify class-size effects combining a regression discontinuity design with…

  16. Leukocyte Rolling on P-Selectin: A Three-Dimensional Numerical Study of the Effect of Cytoplasmic Viscosity

    PubMed Central

    Khismatullin, Damir B.; Truskey, George A.

    2012-01-01

    Rolling leukocytes deform and show a large area of contact with endothelium under physiological flow conditions. We studied the effect of cytoplasmic viscosity on leukocyte rolling using our three-dimensional numerical algorithm that treats leukocyte as a compound droplet in which the core phase (nucleus) and the shell phase (cytoplasm) are viscoelastic fluids. The algorithm includes the mechanical properties of the cell cortex by cortical tension and considers leukocyte microvilli that deform viscoelastically and form viscous tethers at supercritical force. Stochastic binding kinetics describes binding of adhesion molecules. The leukocyte cytoplasmic viscosity plays a critical role in leukocyte rolling on an adhesive substrate. High-viscosity cells are characterized by high mean rolling velocities, increased temporal fluctuations in the instantaneous velocity, and a high probability for detachment from the substrate. A decrease in the rolling velocity, drag, and torque with the formation of a large, flat contact area in low-viscosity cells leads to a dramatic decrease in the bond force and stable rolling. Using values of viscosity consistent with step aspiration studies of human neutrophils (5–30 Pa·s), our computational model predicts the velocities and shape changes of rolling leukocytes as observed in vitro and in vivo. PMID:22768931

  17. An investigation of the effects of pitch-roll (de)coupling on helicopter handling qualities

    NASA Technical Reports Server (NTRS)

    Blanken, C. L.; Pausder, H. J.; Ockier, C. J.

    1995-01-01

    An extensive investigation of the effects of pitch-roll coupling on helicopter handling qualities was performed by the U.S. Army and Deutsche Forschungsanstalt fur Luft- und Raumfahrt (DLR), using a NASA ground-based and a DLR in-flight simulator. Over 90 different coupling configurations were evaluated using a high gain roll-axis tracking task. The results show that although the current ADS-33C coupling criterion discriminates against those types of coupling typical of conventionally controlled helicopters, it is not always suited for the prediction of handling qualities of helicopters with modern control systems. Based on the observation that high frequency inputs during tracking are used to alleviate coupling, a frequency domain pitch-roll coupling criterion that uses the average coupling ratio between the bandwidth and neutral stability frequency is formulated. This criterion provides a more comprehensive coverage with respect to the different types of coupling, shows excellent consistency, and has the additional benefit that compliance testing data are obtained from the bandwidth/phase delay tests, so that no additional flight testing is needed.

  18. The effects of cold rolling on the microstructural and spall response of 1100 aluminum

    NASA Astrophysics Data System (ADS)

    Williams, C. L.; Chen, C. Q.; Ramesh, K. T.; Dandekar, D. P.

    2013-09-01

    As received 1100-O aluminum was cold rolled (CR) to 30%, 70%, and 80% reduction, respectively, to study the effects of microstructural evolution on the spall response using plate impact experiments. Previous results show a sharp increase in pullback velocity for 1100-O aluminum with increase in peak shock stress between 4.0 and 8.3 GPa due to hardening, followed by a decrease for peak shock stresses up to 12.0 GPa possibly due to softening. This maximum was not observed for the 30% CR, which showed only an increase in pullback velocity over the shock stress range of 4.0-12.0 GPa due to hardening (net increase in dislocation density). For the 70% CR aluminum, no change was observed in the pullback velocity over the range tested (4.0-11.0 GPa) probably due to saturation in dislocation density. Similar observations were made for the 80% CR, that is, no change was observed in the spall response between 4.0 GPa and 11.0 GPa. However, variations were observed in the spall response for the 80% CR, and these variations are attributed to material inhomogeneity possibly caused by increased cold rolling beyond saturation. The results also show a significant increase in Hugoniot Elastic Limit with increase in percent cold rolling.

  19. Effect of finishing temperature of hot rolling on recrystallization and mechanical properties of MA 754 plate

    SciTech Connect

    Park, L.J.; Tundermann, J.H.; deBarbadillo, J.J.

    1997-12-15

    Nickel-base oxide-dispersion-strengthened (ODS) alloys produced by the mechanical alloying process have been developed for high temperature applications. In particular, INCONEL{trademark} alloy MA 754 has been used as a turbine vane alloy in advanced jet engines. ODS alloys attract great attention as advanced high temperature materials, because they can retain useful strength up to relatively high fractions of their melting points. The elevated temperature strength of ODS alloys is due to the presence of inert, finely dispersed oxide particles which serve to inhibit the motion of dislocations. In addition to this direct strengthening by oxide particles, the most important microstructural feature affecting elevated temperature strength of ODS alloys is a very coarse grain structure. The aim of this study was to investigate the effect of the finishing temperature (FT) of hot rolling on the microstructure and the secondary recrystallization response of hot rolled INCONEL alloy MA 754 plate. Also, this work addressed the relationship between as-hot rolled microstructure and recrystallized grain structure after secondary recrystallization.

  20. Effect of train type on annoyance and acoustic features of the rolling noise.

    PubMed

    Kasess, Christian H; Noll, Anton; Majdak, Piotr; Waubke, Holger

    2013-08-01

    This study investigated the annoyance associated with the rolling noise of different railway stock. Passbys of nine train types (passenger and freight trains) equipped with different braking systems were recorded. Acoustic features showed a clear distinction of the braking system with the A-weighted energy equivalent sound level (LAeq) showing a difference in the range of 10 dB between cast-iron braked trains and trains with disk or K-block brakes. Further, annoyance was evaluated in a psychoacoustic experiment where listeners rated the relative annoyance of the rolling noise for the different train types. Stimuli with and without the original LAeq differences were tested. For the original LAeq differences, the braking system significantly affected the annoyance with cast-iron brakes being most annoying, most likely as a consequence of the increased wheel roughness causing an increased LAeq. Contribution of the acoustic features to the annoyance was investigated revealing that the LAeq explained up to 94% of the variance. For the stimuli without differences in the LAeq, cast-iron braked train types were significantly less annoying and the spectral features explained up to 60% of the variance in the annoyance. The effect of these spectral features on the annoyance of the rolling noise is discussed.

  1. Annealing effects on the microstructure and mechanical properties of hot-rolled 14Cr-ODS steel

    NASA Astrophysics Data System (ADS)

    Gao, R.; Zhang, T.; Ding, H. L.; Jiang, Y.; Wang, X. P.; Fang, Q. F.; Liu, C. S.

    2015-10-01

    The oxide dispersion strengthened ferritic steels with nominal composition (weight percent) of Fe-14Cr-2W-0.5Ti-0.06Si-0.2V-0.1Mn-0.05Ta-0.03C-0.3Y2O3 were fabricated by sol-gel method, mechanical alloying, and hot isostatic pressing techniques. The evolution of microstructure and mechanical properties of the hot-rolled specimens with heat treatment was investigated. Tensile strength and hardness of hot-rolled ODS steel are significantly enhanced due to the formation of mechanical twins and high density dislocations. Uniformly dispersed oxide particles (10-40 nm) and fine-grained structure (200-400 nm) are responsible for the superior mechanical properties of the hot-rolled specimen annealed between 650 °C and 850 °C. With further increasing annealing temperature, the grain size of the hot-rolled specimens increases while the size of oxide particles decreases, which leads to lower strength and hardness but better ductility. The tensile strength and total elongation of samples in the rolling direction are higher than those in the transverse direction after the same treatments owing to the grain anisotropy induced by the large mechanical deformation.

  2. Cavitation erosion size scale effects

    NASA Technical Reports Server (NTRS)

    Rao, P. V.; Buckley, D. H.

    1984-01-01

    Size scaling in cavitation erosion is a major problem confronting the design engineers of modern high speed machinery. An overview and erosion data analysis presented in this paper indicate that the size scale exponent n in the erosion rate relationship as a function of the size or diameter can vary from 1.7 to 4.9 depending on the type of device used. There is, however, a general agreement as to the values of n if the correlations are made with constant cavitation number.

  3. Effect Sizes in Gifted Education Research

    ERIC Educational Resources Information Center

    Gentry, Marcia; Peters, Scott J.

    2009-01-01

    Recent calls for reporting and interpreting effect sizes have been numerous, with the 5th edition of the "Publication Manual of the American Psychological Association" (2001) calling for the inclusion of effect sizes to interpret quantitative findings. Many top journals have required that effect sizes accompany claims of statistical significance.…

  4. Effect Sizes in Gifted Education Research

    ERIC Educational Resources Information Center

    Gentry, Marcia; Peters, Scott J.

    2009-01-01

    Recent calls for reporting and interpreting effect sizes have been numerous, with the 5th edition of the "Publication Manual of the American Psychological Association" (2001) calling for the inclusion of effect sizes to interpret quantitative findings. Many top journals have required that effect sizes accompany claims of statistical significance.…

  5. Effective Population Sizes with Multiple Paternity

    PubMed Central

    Sugg, D. W.; Chesser, R. K.

    1994-01-01

    While the concept of effective population size is of obvious applicability to many questions in population genetics and conservation biology, its utility has suffered due to a lack of agreement among its various formulations. Often, mathematical formulations for effective sizes apply restrictive assumptions that limit their applicability. Herein, expressions for effective sizes of populations that account for mating tactics, biases in sex ratios, and differential dispersal rates (among other parameters) are developed. Of primary interest is the influence of multiple paternity on the maintenance of genetic variation in a population. In addition to the standard inbreeding and variance effective sizes, intragroup (coancestral) and intergroup effective sizes also are developed. Expressions for effective sizes are developed for the beginning of nonrandom gene exchanges (initial effective sizes), the transition of gene correlations (instantaneous effective sizes), and the steady-state (asymptotic effective size). Results indicate that systems of mating that incorporate more than one male mate per female increase all effective sizes above those expected from polygyny and monogamy. Instantaneous and asymptotic sizes can be expressed relative to the fixation indices. The parameters presented herein can be utilized in models of effective sizes for the study of evolutionary biology and conservation genetics. PMID:7982568

  6. Effects of organic tomato pulp powder and nitrite level on the physicochemical, textural and sensory properties of pork luncheon roll.

    PubMed

    Hayes, J E; Canonico, I; Allen, P

    2013-11-01

    Nine treatments of pork luncheon roll produced with three sodium nitrite levels (0, 0.05 and 0.1%) and three tomato pulp powder (TPP) levels (0, 1.5 and 3%) were assessed at three storage times (2, 7 and 14d). The effects of enrichment with TPP on composition (protein, fat, moisture and ash), pH, colour (CIE L*, a*, b*), nitrosomyoglobin (NOMb) content, lipid oxidation (TBARS), residual nitrite content, total viable count (TVC) texture profile analysis (TPA) and sensory analysis of cooked pork luncheon roll were investigated. Decreasing the level of nitrite increased (p<0.001) the pH, the NOMb value (p<0.001), lipid oxidation (p<0.001) and the residual nitrite content (p<0.001) and affected the colour of the cooked product. The reduction in nitrites had no effect on the composition and texture of the pork luncheon rolls. Adding TPP reduced (p<0.001) the pH and increased (p<0.001) the colour parameters a* and b* of both the raw luncheon roll formulation and the cooked luncheon roll product. TPP, particularly at 3% had a detrimental effect on the texture of pork luncheon rolls by decreasing hardness (p<0.001), gumminess (p<0.001) and chewiness (p<0.001) and increasing cohesiveness (p<0.001). The TBA value increased (p<0.01) with the three main factors (nitrite, TPP, day) but was in all cases well below the 2mg MDA/kg threshold. TVCs for all treatments and storage days were below the TVC limit for this type of cooked product. The pork luncheon roll formulated with 50mg nitrite and 1.5% TPP had similar or enhanced sensory attributes compared to the luncheon roll containing no TPP and a nitrite level of 100mg/kg of product.

  7. The effect of quantity and timing of brine addition on water binding and textural characteristics of cooked beef rolls.

    PubMed

    Pietrasik, Z; Shand, P J

    2003-10-01

    The combined influence of quantity and timing of water/sodium chloride/phosphate addition on quality characteristics of beef rolls processed with 25 or 50% brine level was investigated. Properties of beef rolls were determined by measuring hydration and textural characteristics. The higher level of brine addition (50%) had detrimental effects on product water binding and textural characteristics. Late addition of brine/water during tumbling (i.e. during the last hour) resulted in rolls which were less hard, chewy and elastic, and had poorer water holding properties. Addition of brine in two parts favourably affected hydration properties and thermal stability, yielding lower cooking loss and purge and higher WHC, irrespective of level of brine addition. It also increased hardness and chewiness and improved springiness, cohesiveness and bind of cooked beef rolls.

  8. Effect of head pitch and roll orientations on magnetically induced vertigo.

    PubMed

    Mian, Omar S; Li, Yan; Antunes, Andre; Glover, Paul M; Day, Brian L

    2016-02-15

    Lying supine in a strong magnetic field, such as in magnetic resonance imaging scanners, can induce a perception of whole-body rotation. The leading hypothesis to explain this invokes a Lorentz force mechanism acting on vestibular endolymph that acts to stimulate semicircular canals. The hypothesis predicts that the perception of whole-body rotation will depend on head orientation in the field. Results showed that the direction and magnitude of apparent whole-body rotation while stationary in a 7 T magnetic field is influenced by head orientation. The data are compatible with the Lorentz force hypothesis of magnetic vestibular stimulation and furthermore demonstrate the operation of a spatial transformation process from head-referenced vestibular signals to Earth-referenced body motion. High strength static magnetic fields are known to induce vertigo, believed to be via stimulation of the vestibular system. The leading hypothesis (Lorentz forces) predicts that the induced vertigo should depend on the orientation of the magnetic field relative to the head. In this study we examined the effect of static head pitch (-80 to +40 deg; 12 participants) and roll (-40 to +40 deg; 11 participants) on qualitative and quantitative aspects of vertigo experienced in the dark by healthy humans when exposed to the static uniform magnetic field inside a 7 T MRI scanner. Three participants were additionally examined at 180 deg pitch and roll orientations. The effect of roll orientation on horizontal and vertical nystagmus was also measured and was found to affect only the vertical component. Vertigo was most discomforting when head pitch was around 60 deg extension and was mildest when it was around 20 deg flexion. Quantitative analysis of vertigo focused on the induced perception of horizontal-plane rotation reported online with the aid of hand-held switches. Head orientation had effects on both the magnitude and the direction of this perceived rotation. The data suggest

  9. Hot rolling and annealing effects on the microstructure and mechanical properties of ODS austenitic steel fabricated by electron beam selective melting

    NASA Astrophysics Data System (ADS)

    Gao, Rui; Ge, Wen-jun; Miao, Shu; Zhang, Tao; Wang, Xian-ping; Fang, Qian-feng

    2016-03-01

    The grain morphology, nano-oxide particles and mechanical properties of oxide dispersion strengthened (ODS)-316L austenitic steel synthesized by electron beam selective melting (EBSM) technique with different post-working processes, were explored in this study. The ODS-316L austenitic steel with superfine nano-sized oxide particles of 30-40 nm exhibits good tensile strength (412 MPa) and large total elongation (about 51%) due to the pinning effect of uniform distributed oxide particles on dislocations. After hot rolling, the specimen exhibits a higher tensile strength of 482 MPa, but the elongation decreases to 31.8% owing to the introduction of high-density dislocations. The subsequent heat treatment eliminates the grain defects induced by hot rolling and increases the randomly orientated grains, which further improves the strength and ductility of EBSM ODS-316L steel.

  10. Acorn size effects seedling size at the Penn Nursery

    Treesearch

    Robert P. Karrfalt

    2005-01-01

    The Pennsylvania Department of Conservation and Natural Resources Penn Nursery, located in Spring Mills, PA, was 1 of 4 nurseries participating in a study to determine the effect of acorn sizing on production of northern red oak (Quercus rubra L.) and white oak (Q. alba L.). It is hypothesized that larger acorns would produce...

  11. Numerical investigation about the effect of increasing the number of forming passes on the quality of AHSS roll formed products

    NASA Astrophysics Data System (ADS)

    Badr, Ossama Mamdouh; Rolfe, Bernard; Hodgson, Peter; Weiss, Matthias

    2013-12-01

    Over recent years, roll forming has gained an increasing interest for the manufacture of structural components made of Advanced High Strength Steel (AHSS) sheets. It is an incremental forming technique where the material is bent into the desired shape by feeding it through a number of roll forming stands. Springback is a major concern in forming of AHSS, and springback is lower in roll forming when compared to that in single step and multi-step bending. Some experimental studies suggest that this is may be due to the incremental nature of the roll forming process. In this study the effect of forming passes/steps on springback is numerically analyzed for DP 780 by means of FEA - Abaqus standard. The cyclic hardening characteristics of DP780 were determined by the pure bending test. The hardening model generated from bend data set was imported into Abaqus. The effect forming pattern on the springback was analyzed by forming a V-section shaped profile (15 mm forming radius). The numerical results show that there is a reduction in springback with increasing number of forming passes in the roll forming process, and that this may be the result of straining experienced by the sheet during the multi-step roll forming. This study seems to provide a greater insight into understanding the nature of springback with the forming passes and process design.

  12. Integrated aeroservoelastic synthesis for roll control

    NASA Technical Reports Server (NTRS)

    Nam, Chang-Ho; Weisshaar, Terrence A.

    1990-01-01

    The objective of this study is to illustrate an integrated, parallel design procedure for optimal structural, aerodynamic, and aileron synthesis of an aircraft wing. The effects of combining weight minimization with structural tailoring (ply orientation and thickness) of a lifting surface, together with the wing geometry (sweep angle and taper ratio), and the aileron geometry (spanwise location and chordwise size) upon the lateral control effectiveness are discussed. Several optimization studies for the minimization of aileron hinge moment and wing weight, subject to a specified constant aircraft roll rate at a design airspeed (roll effectiveness), are performed.

  13. Integrated aeroservoelastic synthesis for roll control

    NASA Technical Reports Server (NTRS)

    Nam, Chang-Ho; Weisshaar, Terrence A.

    1990-01-01

    The objective of this study is to illustrate an integrated, parallel design procedure for optimal structural, aerodynamic, and aileron synthesis of an aircraft wing. The effects of combining weight minimization with structural tailoring (ply orientation and thickness) of a lifting surface, together with the wing geometry (sweep angle and taper ratio), and the aileron geometry (spanwise location and chordwise size) upon the lateral control effectiveness are discussed. Several optimization studies for the minimization of aileron hinge moment and wing weight, subject to a specified constant aircraft roll rate at a design airspeed (roll effectiveness), are performed.

  14. Effect of Fiber Orientation on Ball Failures Under Rolling-contact Conditions

    NASA Technical Reports Server (NTRS)

    Butler, Robert H; Bear, H Robert; Carter, Thomas L

    1957-01-01

    The rolling-contact fatigue spin rig was used to test bails of a bearing steel at maximum Hertz stresses of 600,000 to 750,000 psi. The effect of fiber orientation was observed with the ball track restricted to passing directly over the poles, coincident with the equator, or randomly around the ball. The polar areas were found to be weaker in fatigue than the nonpolar areas. This resulted in a much greater portion of the failures occurring in the polar areas than would be expected from a homogeneous material. The early failures are discussed.

  15. The effects of prosthetic foot roll-over shape arc length on the gait of trans-tibial prosthesis users.

    PubMed

    Hansen, Andrew H; Meier, Margrit R; Sessoms, Pinata H; Childress, Dudley S

    2006-12-01

    The Shape&Roll prosthetic foot was used to examine the effect of roll-over shape arc length on the gait of 14 unilateral trans-tibial prosthesis users. Simple modifications to the prosthetic foot were used to alter the effective forefoot rocker length, leaving factors such as alignment, limb length, and heel and mid-foot characteristics unchanged. Shortening the roll-over shape arc length caused a significant reduction in the maximum external dorsiflexion moment on the prosthetic side at all walking speeds (p < 0.001 for main effect of arc length), due to a reduction in forefoot leverage (moment arm) about the ankle. Roll-over shape arc length significantly affected the initial loading on the sound limb at normal and fast speeds (p = 0.001 for the main effect of arc length), with participants experiencing larger first peaks of vertical ground reaction forces on their sound limbs when using the foot with the shortest effective forefoot rocker arc length. Additionally, the difference between step lengths on the sound and prosthetic limbs was larger with the shortest arc length condition, although this difference was not statistically significant (p = 0.06 for main effect). It appears that prosthesis users may experience a drop-off effect at the end of single limb stance on prosthetic feet with short roll-over shape arc lengths, leading to increased loading and/or a shortened step on the contralateral limb.

  16. Effects of Alloying Elements on Microstructure, Hardness, Wear Resistance, and Surface Roughness of Centrifugally Cast High-Speed Steel Rolls

    NASA Astrophysics Data System (ADS)

    Ha, Dae Jin; Sung, Hyo Kyung; Park, Joon Wook; Lee, Sunghak

    2009-11-01

    A study was made of the effects of carbon, tungsten, molybdenum, and vanadium on the wear resistance and surface roughness of five high-speed steel (HSS) rolls manufactured by the centrifugal casting method. High-temperature wear tests were conducted on these rolls to experimentally simulate the wear process during hot rolling. The HSS rolls contained a large amount (up to 25 vol pct) of carbides, such as MC, M2C, and M7C3 carbides formed in the tempered martensite matrix. The matrix consisted mainly of tempered lath martensite when the carbon content in the matrix was small, and contained a considerable amount of tempered plate martensite when the carbon content increased. The high-temperature wear test results indicated that the wear resistance and surface roughness of the rolls were enhanced when the amount of hard MC carbides formed inside solidification cells increased and their distribution was homogeneous. The best wear resistance and surface roughness were obtained from a roll in which a large amount of MC carbides were homogeneously distributed in the tempered lath martensite matrix. The appropriate contents of the carbon equivalent, tungsten equivalent, and vanadium were 2.0 to 2.3, 9 to 10, and 5 to 6 pct, respectively.

  17. Sulfation of a high endothelial venule-expressed ligand for L-selectin. Effects on tethering and rolling of lymphocytes.

    PubMed

    Tangemann, K; Bistrup, A; Hemmerich, S; Rosen, S D

    1999-10-04

    During lymphocyte homing, L-selectin mediates the tethering and rolling of lymphocytes on high endothelial venules (HEVs) in secondary lymphoid organs. The L-selectin ligands on HEV are a set of mucin-like glycoproteins, for which glycosylation-dependent cell adhesion molecule 1 (GlyCAM-1) is a candidate. Optimal binding in equilibrium measurements requires sulfation, sialylation, and fucosylation of ligands. Analysis of GlyCAM-1 has revealed two sulfation modifications (galactose [Gal]-6-sulfate and N-acetylglucosamine [GlcNAc]-6-sulfate) of sialyl Lewis x. Recently, three related sulfotransferases (keratan sulfate galactose-6-sulfotransferase [KSGal6ST], high endothelial cell N-acetylglucosamine-6-sulfotransferase [GlcNAc6ST], and human GlcNAc6ST) were cloned, which can generate Gal-6-sulfate and GlcNAc-6-sulfate in GlyCAM-1. Imparting these modifications to GlyCAM-1, together with appropriate fucosylation, yields enhanced rolling ligands for both peripheral blood lymphocytes and Jurkat cells in flow chamber assays as compared with those generated with exogenous fucosyltransferase. Either sulfation modification results in an increased number of tethered and rolling lymphocytes, a reduction in overall rolling velocity associated with more frequent pausing of the cells, and an enhanced resistance of rolling cells to detachment by shear. All of these effects are predicted to promote the overall efficiency of lymphocyte homing. In contrast, the rolling interactions of E-selectin transfectants with the same ligands are not affected by sulfation.

  18. Semiclassical relations and IR effects in de Sitter and slow-roll space-times

    SciTech Connect

    Giddings, Steven B.; Sloth, Martin S. E-mail: sloth@cern.ch

    2011-01-01

    We calculate IR divergent graviton one-loop corrections to scalar correlators in de Sitter space, and show that the leading IR contribution may be reproduced via simple semiclassical consistency relations. One can likewise use such semiclassical relations to calculate leading IR corrections to correlators in slow-roll inflation. The regulated corrections shift the tensor/scalar ratio and consistency relation of single field inflation, and non-gaussianity parameters averaged over very large distances. For inflation of sufficient duration, for example arising from a chaotic inflationary scenario, these corrections become of order unity. First-order corrections of this size indicate a breakdown of the perturbative expansion, and suggest the need for a non-perturbative description of the corresponding regime. This is analogous to a situation argued to arise in black hole evolution, and to interfere with a sharp perturbative calculation of ''missing information'' in Hawking radiation.

  19. Simulation of the thermal conditions of rolls in a wide-strip hot-rolling mill to determine their effective cooling conditions

    NASA Astrophysics Data System (ADS)

    Garber, E. A.; Khlopotin, M. V.; Traino, A. I.; Popov, E. S.; Savinykh, A. F.

    2009-06-01

    An advanced procedure is developed for the thermal calculation of the rolls in a wide-strip hot-rolling mill (WSHRM). It combines the following two adaptive models: the thermal balance in the active surface layer in a roll per revolution and the thermal balance in the main zones of work and backup rolls with axisymmetric temperature fields with allowance for the heat exchange between a strip, rolls, the coolant, and the environment. In contrast to the well-known models, this advanced procedure calculates the bulk mean temperature and the thermal profile in a roll more accurately, since the temperature drop across the surface layer in this procedure is calculated allowing for the intensities of the contact and convective heat exchange between rolls. Data on the coefficient of heat transfer from rolls to the coolant supplied at an excess pressure of 1.0-1.5 MPa are presented for the first time. This procedure is used in a 2000 WSHRM and improves the transverse profile of hot-rolled strips due to a stabilized thermal profile in rolls.

  20. Rolling Reloaded

    ERIC Educational Resources Information Center

    Jones, Simon A.; Nieminen, John M.

    2008-01-01

    Not so long ago a new observation about rolling motion was described: for a rolling wheel, there is a set of points with instantaneous velocities directed at or away from the centre of the wheel; these points form a circle whose diameter connects the centre of the wheel to the wheel's point of contact with the ground (Sharma 1996 "Eur. J. Phys."…

  1. Do Class Size Effects Differ across Grades?

    ERIC Educational Resources Information Center

    Nandrup, Anne Brink

    2016-01-01

    This paper contributes to the class size literature by analysing whether short-run class size effects are constant across grade levels in compulsory school. Results are based on administrative data on all pupils enrolled in Danish public schools. Identification is based on a government-imposed class size cap that creates exogenous variation in…

  2. Do Class Size Effects Differ across Grades?

    ERIC Educational Resources Information Center

    Nandrup, Anne Brink

    2016-01-01

    This paper contributes to the class size literature by analysing whether short-run class size effects are constant across grade levels in compulsory school. Results are based on administrative data on all pupils enrolled in Danish public schools. Identification is based on a government-imposed class size cap that creates exogenous variation in…

  3. Effects of rolling temperature on microstructure, texture, formability and magnetic properties in strip casting Fe-6.5 wt% Si non-oriented electrical steel

    NASA Astrophysics Data System (ADS)

    Liu, Hai-Tao; Li, Hao-Ze; Li, Hua-Long; Gao, Fei; Liu, Guo-Huai; Luo, Zhong-Han; Zhang, Feng-Quan; Chen, Sheng-Lin; Cao, Guang-Ming; Liu, Zhen-Yu; Wang, Guo-Dong

    2015-10-01

    Fe-6.5 wt% Si non-oriented electrical steel sheets with a thickness of 0.50 mm were produced by using a new processing route: strip casting followed by hot rolling, intermediate temperature (150-850 °C) rolling and final annealing. The present study focused on exploring the effects of rolling temperature varying from 150 to 850 °C on the microstructure and texture evolution, the formability and final magnetic properties. The microstructure and texture evolution at the various processing steps were investigated in detail by using OM, XRD, EBSD and TEM. It was found that the formability during rolling, the microstructure and texture before and after annealing and final magnetic properties highly depended on rolling temperature. The formability during rolling was gradually improved with increasing rolling temperature due to the slipping of dislocation. In particular, the rolling temperature dominated the formation of in-grain shear bands in the rolled microstructure, which played an important role in the development of final recrystallization microstructure and texture. In the case of lower temperature (150-450 °C) rolling, an inhomogeneous microstructure with a large amount of in-grain shear bands was formed in the rolled sheets, which finally resulted in a fine and inhomogeneous annealing microstructure dominated by mild λ-fiber texture composed of cube and {001}<210> components and α*-fiber texture concentrated on {115}<5-10 1> component. By contrast, in the case of higher temperature (650-850 °C) rolling, a relatively homogeneous microstructure without in-grain shear bands was formed instead in the rolled sheets, which finally led to a coarse and relatively homogeneous annealing microstructure characterized by strong α-fiber and γ-fiber texture. Accordingly, on the whole, both the magnetic induction (B8 and B50) and iron loss (P15/50 and P10/400) decreased with raising rolling temperature.

  4. Hysteresis effects of the subjective visual vertical during continuous quasi-static whole-body roll rotation.

    PubMed

    Palla, A; Tatalias, M; Straumann, D

    2008-01-01

    Healthy human subjects, when roll tilted in darkness, make systematic errors in estimating subjective visual vertical (SVV). Typically, roll tilt underestimation occurs at angles beyond 60 degrees (A-effect). At smaller tilt angles, overestimation may occur (E-effect). At approximately 135 degrees whole-body roll tilt, Kaptein and Van Gisbergen (2004, 2005) found an abrupt A/E transition, the exact location of which depended on the preceding rotation direction indicating hysteresis. Since this was observed using relatively fast roll velocity, it remains unclear whether the described hysteresis is dynamic or static. To clarify this uncertainty, we continuously rotated nine healthy subjects about the earth-horizontal naso-occipital axis, while they performed SVV adjustments every 2 s. Starting from the upright position, three full quasi-static constant velocity rotations (2 degrees/s) were completed in both directions (CW: clockwise; CCW: counterclockwise). SVV deviation from earth-verticality was plotted as a function of whole-body roll position. A bimodal Gaussian distribution function was fitted to SVV differences between CW and CCW rotations. A-effects (peaks at 88 degrees and 257 degrees chair position) at identical whole-body positions were larger after rotations from upside-down than after rotations from upright (average peak difference: 26 degrees). These results demonstrate static hysteresis for SVV estimation.

  5. Effect of Accumulative Roll Bonding on Plastic Flow Properties of Commercially Pure Zirconium

    SciTech Connect

    Sabirov, I.; Molina-Aldareguia, J. M.; Perez-Prado, M. T.; Jiang, L.; Kassner, M. E.

    2011-05-04

    Accumulative roll bonding (ARB) has been considered as one of the promising techniques for fabrication of ultra-fine grained (UFG) metallic materials. The ARB process consists of several cycles of cutting, stacking, and rolling of metal sheets, so very high strains can be induced in the material resulting in significant grain refinement and in the formation of UFG microstructures. The ARB technique has been applied to a wide range of metallic materials such as Al and Al alloys, Mg, Fe and steels, Zr, Cu, as well as composite materials. UFG metallic materials processed via ARB show increased strength. Despite a significant body of experimental research into the deformation behaviour of the ARB-processed materials, the fundamentals of their plastic deformation are not fully understood yet. This work focuses on the effect of grain refinement via ARB-processing on the mechanical behavior and on the strain-rate sensitivity of commercially pure Zr (99.8% purity). The mechanical properties of the as-received coarse-grained (CG) and UFG (as-ARB processed) samples were studied at room temperature at two different strain rates. Mechanical strain rate jump tests were performed during tensile deformation to estimate the instantaneous strain-rate sensitivity. The evolution of surface relief during plastic deformation of pure Zr in both CG and UFG conditions was studied. The features of plastic deformation of pure Zr in both CG and UFG conditions are discussed.

  6. Generalized slow roll in the unified effective field theory of inflation

    NASA Astrophysics Data System (ADS)

    Motohashi, Hayato; Hu, Wayne

    2017-07-01

    We provide a compact and unified treatment of power spectrum observables for the effective field theory (EFT) of inflation with the complete set of operators that lead to second-order equations of motion in metric perturbations in both space and time derivatives, including Horndeski and Gleyzes-Langlois-Piazza-Vernizzi theories. We relate the EFT operators in ADM form to the four additional free functions of time in the scalar and tensor equations. Using the generalized slow-roll formalism, we show that each power spectrum can be described by an integral over a single source that is a function of its respective sound horizon. With this correspondence, existing model independent constraints on the source function can be simply reinterpreted in the more general inflationary context. By expanding these sources around an optimized freeze-out epoch, we also provide characterizations of these spectra in terms of five slow-roll hierarchies whose leading-order forms are compact and accurate as long as EFT coefficients vary only on time scales greater than an e -fold. We also clarify the relationship between the unitary gauge observables employed in the EFT and the comoving gauge observables of the postinflationary universe.

  7. Effect of Microstructural Anisotropy on the Dynamic Mechanical Behaviour of Rolled Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Lock, A. C. H.; Brown, A. D.; Blessington, R. A.; Appleby-Thomas, G.; Quadir, Md. Z.; Hazell, P. J.; Escobedo, J. P.

    The effect of microstructural anisotropy on the mechanical behavior of a hot rolled Ti-6Al-4V alloy has been investigated. Quasi-static and dynamic experiments in compression and tension were conducted on specimens with their deformation axis aligned along the rolling (RD), transverse (TD), and through thickness (TT) directions. Digital image correlation (DIC) was utilized to observe in-situ the development of deformation fields. Optic al and electron backscatter diffraction (EBSD) microscopy were conducted on pristine and deformed specimens to examine the microstructural evolution for each loading profile. Initial characterization results show that the plate possesses a preferred orientation of the c-axis along the TD direction and about 40° from the TT. This resulted in the TD direction showing a tensile strength 12% greater than RD and TT for all loading profiles. Post mortem characterization confirms these results as they reveal the presence of adiabatic shear bands with an accompanying localized re-orientation of the c-axes by 90°, indicative of substantial tensile twinning.

  8. Improvement of rolling 6 mm thin plates in plate rolling mill PT. Krakatau Posco

    NASA Astrophysics Data System (ADS)

    Pujiyanto, Hamdani

    2017-01-01

    A 6-mm thin plate is difficult to produce especially if the product requires wide size and high strength. Flatness is the main quality issue in rolling 6-mm plate using a 4-high reversing mill which use ±1100-mm work roll. Thus some methods are applied to overcome such issue in order to comply to customer quality requirement. Pre-rolling, rolling, and post-rolling conditions have to be considered comprehensively. Roll unit management will be the key factor before rolling condition. The roll unit itself has a significant impact on work roll crown wearness in relation with work roll intial crown and thermal crown. Work roll crown along with the modification of hydraulic gap control (HGC) could directly alter the flatness of the plate.

  9. Effects of Deformation Behavior and Processing Temperature on the Fatigue Performance of Deep-Rolled Medium Carbon Bar Steels

    NASA Astrophysics Data System (ADS)

    Richards, M. D.; Burnett, M. E.; Speer, J. G.; Matlock, D. K.

    2013-01-01

    The effects of processing temperature on the deep-rolling response of three medium carbon bar steels, a quenched and tempered 4140 alloy, a 0.34C, 1.21Mn, 0.66Si nontraditional bainitic alloy, and a 0.36C, 1.37Mn V-microalloyed ferrite plus pearlite steel, was assessed through bending fatigue. The significantly different deformation behaviors of the three alloys were characterized through standard and nonstandard quasi-static and cyclic uniaxial tension and compression tests at room temperature (RT) and in situ at temperatures up to 634 K. Deep rolling, performed at RT and at elevated temperature (HT) in the dynamic strain-aging (DSA) regime, increased measured endurance limits by 51-62 pct (RT) and 96-117 pct (HT) as compared with the baseline condition. The enhanced fatigue performance by RT deep rolling primarily reflected the effects of the introduction of favorable residual stresses. The improved fatigue performance from HT deep rolling was attributed to the enhanced resistance to strain reversal of the material deformed during deep rolling, due to a change in deformation mechanism from dislocation-interstitial interactions in the DSA regime during processing, which inhibited mechanically induced relaxation of residual stress during cyclic loading.

  10. Hazards of explosives dusts: Particle size effects

    SciTech Connect

    Cashdollar, K L; Hertzberg, M; Green, G M

    1992-02-01

    At the request of the Department of Energy, the Bureau of Mines has investigated the hazards of military explosives dispersed as dust clouds in a 20-L test chamber. In this report, the effect of particle size for HMX, HNS, RDX, TATB, and TNT explosives dusts is studied in detail. The explosibility data for these dusts are also compared to those for pure fuel dusts. The data show that all of the sizes of the explosives dusts that were studied were capable of sustaining explosions as dust clouds dispersed in air. The finest sizes (<10 [mu]m) of explosives dusts were less reactive than the intermediate sizes (20 to 60 [mu]m); this is opposite to the particle size effect observed previously for the pure fuel dusts. At the largest sizes studied, the explosives dusts become somewhat less reactive as dispersed dust clouds. The six sizes of the HMX dust were also studied as dust clouds dispersed in nitrogen.

  11. Effect of controlled cooling on the formability of TS 590 MPa grade hot-rolled high strength steels

    NASA Astrophysics Data System (ADS)

    Cho, Yeol-Rae; Chung, Jin-Hwan; Ku, Hwang-Hoe; Kim, In-Bae

    1999-12-01

    The effect of cooling on the mechanical properties of hot-rolled high strength steels was investigated in order to improve the stretch-flangeability of conventional TS 590 MPa grade for the automotive parts through laboratory simulation and mill-scale production. The low temperature coiling method using a 3-step controlled cooling pattern after hot rolling was very effective for producing Nb-bearing high strength steel with high stretch- flangeability. It was suggested that the suppressed precipitation of grain boundary cementites and the decreased hardness difference between the ferrite matrix and bainite phases cause the excellent stretch-flangeability of ferrite-bainite duplex microstructure steel. Therefore, the formation and propagation of microcracks were suppressed relative to conventional HSLA steel with the ferrite and pearlite microstructure. In addition, the elongation improved compared with that of hot-rolled steel sheets using the conventional early cooling pattern because the volume fraction of polygonal ferrite increased.

  12. Mathematical Modeling of the Twin Roll Casting Process for AZ31 Magnesium Alloy - Effect of Set-Back Distance

    NASA Astrophysics Data System (ADS)

    Hadadzadeh, Amir; Wells, Mary; Essadiqi, Elhachmi

    A 2-D coupled thermal-fluid-stress model was developed and used to simulate the twin roll casting (TRC) of an AZ31 magnesium alloy using the commercial software package, ALSIM. The model was used to predict the fluid flow, temperature distribution and mechanical behavior of AZ31 magnesium alloy in the roll bite. An important parameter in controlling the TRC process is the set-back distance; the distance between the nozzle entry to the kissing point of the rolls. There are two approaches to increase the set-back: 1) increasing the entry thickness and 2) decreasing the final strip thickness. In this study the effect of set-back distance and casting speed on the thermo-mechanical behavior of the strip during TRC has been studied. The thermo-mechanical behavior of the strip has a significant effect on the final quality as defect formation depends on such behavior.

  13. Computing & Interpreting Effect Sizes in Educational Research

    ERIC Educational Resources Information Center

    Thompson, Bruce

    2009-01-01

    The present article provides a primer on using effect sizes in research. A small heuristic data set is used in order to make the discussion concrete. Additionally, various admonitions for best practice in reporting and interpreting effect sizes are presented. Among these is the admonition to not use Cohen's benchmarks for "small," "medium," and…

  14. Rolling Ribbons

    NASA Astrophysics Data System (ADS)

    Raux, P. S.; Reis, P. M.; Bush, J. W. M.; Clanet, C.

    2010-07-01

    We present the results of a combined experimental and theoretical investigation of rolling elastic ribbons. Particular attention is given to characterizing the steady shapes that arise in static and dynamic rolling configurations. In both cases, above a critical value of the forcing (either gravitational or centrifugal), the ribbon assumes a two-lobed, peanut shape similar to that assumed by rolling droplets. Our theoretical model allows us to rationalize the observed shapes through consideration of the ribbon’s bending and stretching in response to the applied forcing.

  15. Relative effect(s) of texture and grain size on magnetic properties in a low silicon non-grain oriented electrical steel

    NASA Astrophysics Data System (ADS)

    PremKumar, R.; Samajdar, I.; Viswanathan, N. N.; Singal, V.; Seshadri, V.

    2003-08-01

    Hot rolled low Si (silicon) non-grain oriented electrical steel was cold rolled to different reductions. Cold rolled material was subsequently recrystallized, 650°C and 2 h, and then temper rolled (to 7% reduction) for the final grain growth annealing and decarburization treatment at 850°C for 2-24 h. The development of texture, grain size and magnetic properties were characterized at different stages of processing. Effect of texture on magnetic properties (watt loss and permeability) was observed to be best represented by the ratio of volume fractions of (1 1 1)/(0 0 1) fibers, as estimated by convoluting X-ray ODFs (orientation distribution functions) with respective model functions. Such a ratio was termed as generalized texture factor (tf) for the non-grain oriented electrical steel. An effort was made to delink effects of grain size and texture, as represented by respective tf, on watt loss and permeability by careful analysis of experimental data. In general, low tf and/or high grain size were responsible for low watt loss and high permeability. However, individual effect of grain size or tf on magnetic properties was less significant at low tf or large grain size, respectively. An attempt was made to fit regression equations, namely—linear, exponential and power, relating magnetic properties with tf and grain size, limiting the fitting parameters to 3. Least standard deviations, between experimental and predicted values, were obtained by power regression equations for both magnetic properties.

  16. Structural effect of size on interracial friendship

    PubMed Central

    Cheng, Siwei; Xie, Yu

    2013-01-01

    Social contexts exert structural effects on individuals’ social relationships, including interracial friendships. In this study, we posit that, net of group composition, total context size has a distinct effect on interracial friendship. Under the assumptions of (i) maximization of preference in choosing a friend, (ii) multidimensionality of preference, and (iii) preference for same-race friends, we conducted analyses using microsimulation that yielded three main findings. First, increased context size decreases the likelihood of forming an interracial friendship. Second, the size effect increases with the number of preference dimensions. Third, the size effect is diluted by noise, i.e., the random component affecting friendship formation. Analysis of actual friendship data among 4,745 American high school students yielded results consistent with the main conclusion that increased context size promotes racial segregation and discourages interracial friendship. PMID:23589848

  17. Structural effect of size on interracial friendship.

    PubMed

    Cheng, Siwei; Xie, Yu

    2013-04-30

    Social contexts exert structural effects on individuals' social relationships, including interracial friendships. In this study, we posit that, net of group composition, total context size has a distinct effect on interracial friendship. Under the assumptions of (i) maximization of preference in choosing a friend, (ii) multidimensionality of preference, and (iii) preference for same-race friends, we conducted analyses using microsimulation that yielded three main findings. First, increased context size decreases the likelihood of forming an interracial friendship. Second, the size effect increases with the number of preference dimensions. Third, the size effect is diluted by noise, i.e., the random component affecting friendship formation. Analysis of actual friendship data among 4,745 American high school students yielded results consistent with the main conclusion that increased context size promotes racial segregation and discourages interracial friendship.

  18. Effective population size of korean populations.

    PubMed

    Park, Leeyoung

    2014-12-01

    Recently, new methods have been developed for estimating the current and recent changes in effective population sizes. Based on the methods, the effective population sizes of Korean populations were estimated using data from the Korean Association Resource (KARE) project. The overall changes in the population sizes of the total populations were similar to CHB (Han Chinese in Beijing, China) and JPT (Japanese in Tokyo, Japan) of the HapMap project. There were no differences in past changes in population sizes with a comparison between an urban area and a rural area. Age-dependent current and recent effective population sizes represent the modern history of Korean populations, including the effects of World War II, the Korean War, and urbanization. The oldest age group showed that the population growth of Koreans had already been substantial at least since the end of the 19th century.

  19. Study the effect of surface texturing on the stress distribution of UHMWPE as a bearing material during rolling motion

    NASA Astrophysics Data System (ADS)

    Jamari, J.; Ismail, R.; Anwar, I. B.; Saputra, E.; Tauviqirrahman, M.; Heide, E. V. D.

    2016-04-01

    Tribological properties of materials used in biomedical implants will critically affect the performance of the implant. Ultra-high molecular weight polyethylene (UHMWPE) material is popular due to its great properties. Surface texturing is one of the methods to minimize friction and wear. In this study, the effect of surface texturing on the stress distribution of UHMWPE as a bearing material has been investigated for rolling motion. The study was performed by finite element analysis. Several three-dimensional surfaces were created by varying its texture. The texture consists of several cylindrical cavities for certain separation. These surfaces were then rolled by a hard ball indenter. The stress distribution due to the rolling contact for each surface was analyzed. Results show that the surface demonstrates a higher stress distribution for the lower separation between the cylindrical cavities.

  20. The effect of rolling on graphitization characteristics of strip cast Fe-C-Si white cast iron

    SciTech Connect

    Song, J.M.; Kuo, B.C.; Lui, T.S.; Chen, L.H.

    2000-01-01

    This study examined the first-stage graphitization of white cast iron strip after rolling. Experimental results confirmed that prerolling promotes and accelerates graphitization. The critical complete graphitization time was significantly shortened even after a small rolling reduction, and the number of temper graphite particles increased with increasing rolling reduction. Some of the evidence confirmed that these effects can be attributed to microstructural defects introduced by prerolling. These defects contribute to a shorter incubation period, a decreased complete graphitization time, and an increased number of temper graphite nucleation sites. In addition, this study adds further evidence to the assumption that graphite nucleation occurs at the interface between eutectic cementite and matrix, particularly in deformation cracking on eutectic cementite.

  1. Rolling Robot

    NASA Technical Reports Server (NTRS)

    Larimer, Stanley J.; Lisec, Thomas R.; Spiessbach, Andrew J.

    1990-01-01

    Proposed rolling robot routinely traverses rough terrain, clearing rocks as high as 1 m. Climbs steps 1 m high and spans ditches 2.3 m wide. Simple but rugged semiautonomous rover has large wheels and articulated body. With combined yaw, roll, and four-wheel drive, robot crawls slowly to pass over soft or sandy terrain. Senses terrain along corridor, chooses path to avoid insurmountable obstacles, and monitors state of vehicle for unexpected hazards.

  2. The Effect of Indenter Ball Radius on the Static Load Capacity of the Superelastic 60NiTi for Rolling Element Bearings

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Moore, Lewis E.; Clifton, Joshua S.

    2014-01-01

    Static load capacity is a critical design parameter for rolling element bearings used in space mechanisms because of the potential for Brinell (surface dent) damage due to shock and vibration loading events during rocket launch. Brinell damage to bearing raceways can lead to torque variations (noise) and reduced bearing life. The growing use of ceramic rolling elements with high stiffness in hybrid bearings exacerbates the situation. A new family of hard yet resilient materials based upon nickel-titanium is emerging to address such bearing challenges. 60NiTi is a superelastic material that simultaneously exhibits high hardness and a relatively low elastic modulus (100GPa) and has been shown to endure higher indentation loads than conventional and high performance steel. Indentation load capacity has been reported for relatively large (12.7mm diameter) ceramic (Si3N4) indenter balls pressed against flat plates of 60NiTi. In order to develop damage load threshold criteria applicable to a wide range of bearing designs and sizes, the effects of indenter ball radius and the accuracy of interpolation of the Hertz contact stress relations for 60NiTi must be ascertained. In this paper, results of indentation tests involving ceramic balls ranging from 6.4 to 12.7mm in diameter and highly polished 60NiTi flat plates are presented. When the resulting dent depth data for all the indenter ball sizes are normalized using the Hertz equations, the data (dent depth vs. stress) are comparable. Thus when designing bearings made from 60NiTi, the Hertz stress relations can be applied with relative confidence over a range of rolling element sizes and internal geometries.

  3. The Effect of Indenter Ball Radius on the Static Load Capacity of the Superelastic 60NiTi for Rolling Element Bearings

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher; Moore, Lewis E.

    2014-01-01

    Static load capacity is a critical design parameter for rolling element bearings used in space mechanisms because of the potential for Brinell (surface dent) damage due to shock and vibration loading events during rocket launch. Brinell damage to bearing raceways can lead to torque variations (noise) and reduced bearing life. The growing use of ceramic rolling elements with high stiffness in hybrid bearings exacerbates the situation. A new family of hard yet resilient materials based upon nickel-titanium is emerging to address such bearing challenges. 60NiTi is a superelastic material that simultaneously exhibits high hardness and a relatively low elastic modulus (approx. 100 GPa) and has been shown to endure higher indentation loads than conventional and high performance steel. Indentation load capacity has been reported for relatively large (12.7 mm diameter) ceramic (Si3N4) indenter balls pressed against flat plates of 60NiTi. In order to develop damage load threshold criteria applicable to a wide range of bearing designs and sizes, the effects of indenter ball radius and the accuracy of interpolation of the Hertz contact stress relations for 60NiTi must be ascertained. In this paper, results of indentation tests involving ceramic balls ranging from 6.4 to 12.7 mm in diameter and highly polished 60NiTi flat plates are presented. When the resulting dent depth data for all the indenter ball sizes are normalized using the Hertz equations, the data (dent depth versus stress) are comparable. Thus when designing bearings made from 60NiTi, the Hertz stress relations can be applied with relative confidence over a range of rolling element sizes and internal geometries.

  4. The Effect of Indenter Ball Radius on the Static Load Capacity of the Superelastic 60NiTi for Rolling Element Bearings

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Moore, Lewis E., III; Clifton, Joshua S.

    2014-01-01

    Static load capacity is a critical design parameter for rolling element bearings used in space mechanisms because of the potential for Brinell (surface dent) damage due to shock and vibration loading events during rocket launch. Brinell damage to bearing raceways can lead to torque variations (noise) and reduced bearing life. The growing use of ceramic rolling elements with high stiffness in hybrid bearings exacerbates the situation. A new family of hard yet resilient materials based upon nickel-titanium is emerging to address such bearing challenges. 60NiTi is a superelastic material that simultaneously exhibits high hardness and a relatively low elastic modulus (approx. 100 GigaPascals) and has been shown to endure higher indentation loads than conventional and high performance steel. Indentation load capacity has been reported for relatively large (12.7 millimeters diameter) ceramic (Si3N4) indenter balls pressed against flat plates of 60NiTi. In order to develop damage load threshold criteria applicable to a wide range of bearing designs and sizes, the effects of indenter ball radius and the accuracy of interpolation of the Hertz contact stress relations for 60NiTi must be ascertained. In this paper, results of indentation tests involving ceramic balls ranging from 6.4 to 12.7 mm in diameter and highly polished 60NiTi flat plates are presented. When the resulting dent depth data for all the indenter ball sizes are normalized using the Hertz equations, the data (dent depth versus stress) are comparable. Thus when designing bearings made from 60NiTi, the Hertz stress relations can be applied with relative confidence over a range of rolling element sizes and internal geometries.

  5. Effects of cold rolling on the microstructure and mechanical properties of Fe-Ni-Mn-Mo-Ti-Cr maraging steels

    NASA Astrophysics Data System (ADS)

    Mahmudi, Abbas; Nedjad, Syamak Hossein; Behnam, Mir Masud Jabbari

    2011-10-01

    Effects of cold rolling on the microstructure and mechanical properties of Fe-Ni-Mn-Mo-Ti-Cr maraging steels were studied. To investigate the microstructure and mechanical properties, optical microscopy, scanning electron microscopy, X-ray diffraction, tensile test, and hardness test were used. The results show that the solution-annealing treatment in the cold-rolled steel redounds to the formation of submicrocrystalline Fe2(Mo, Ti) Laves phase particles, which are stable at high temperatures. These secondary Laves phase particles prevent from recrystallization at high temperatures and correspond to semi-brittle fracture in the subsequent aging treatment.

  6. Aerodynamics in ground effect and predicted landing ground roll of a fighter configuration with a secondary-nozzle thrust reverser

    NASA Technical Reports Server (NTRS)

    Banks, Daniel W.

    1988-01-01

    An experimental investigation of the in-ground effect aerodynamic characteristics and predicted landing-ground-roll performance of wing-canard fighter configuration with a secondary nozzle thrust reverser was completed. These tests were conducted in the Langley 14 by 22 foot Subsonic Wind Tunnel using a model equipped with a pneumatic jet for thrust simulation of nozzle pressure ratios up to 4.0. The model was tested in the landing rollout configuration at approx. wheel touchdown height for a range of decreasing dynamic pressure from 50 psf down to 10 psf. Landing-ground-roll predictions of the configuration were calculated using the wind tunnel results.

  7. GRCop-84 Rolling Parameter Study

    NASA Technical Reports Server (NTRS)

    Loewenthal, William S.; Ellis, David L.

    2008-01-01

    This report is a section of the final report on the GRCop-84 task of the Constellation Program and incorporates the results obtained between October 2000 and September 2005, when the program ended. NASA Glenn Research Center (GRC) has developed a new copper alloy, GRCop-84 (Cu-8 at.% Cr-4 at.% Nb), for rocket engine main combustion chamber components that will improve rocket engine life and performance. This work examines the sensitivity of GRCop-84 mechanical properties to rolling parameters as a means to better define rolling parameters for commercial warm rolling. Experiment variables studied were total reduction, rolling temperature, rolling speed, and post rolling annealing heat treatment. The responses were tensile properties measured at 23 and 500 C, hardness, and creep at three stress-temperature combinations. Understanding these relationships will better define boundaries for a robust commercial warm rolling process. The four processing parameters were varied within limits consistent with typical commercial production processes. Testing revealed that the rolling-related variables selected have a minimal influence on tensile, hardness, and creep properties over the range of values tested. Annealing had the expected result of lowering room temperature hardness and strength while increasing room temperature elongations with 600 C (1112 F) having the most effect. These results indicate that the process conditions to warm roll plate and sheet for these variables can range over wide levels without negatively impacting mechanical properties. Incorporating broader process ranges in future rolling campaigns should lower commercial rolling costs through increased productivity.

  8. Discomfort of seated persons exposed to low frequency lateral and roll oscillation: effect of seat cushion.

    PubMed

    Beard, George F; Griffin, Michael J

    2014-11-01

    The discomfort caused by lateral oscillation, roll oscillation, and fully roll-compensated lateral oscillation has been investigated at frequencies between 0.25 and 1.0 Hz when sitting on a rigid seat and when sitting on a compliant cushion, both without a backrest. Judgements of vibration discomfort and the transmission of lateral and roll oscillation through the seat cushion were obtained with 20 subjects. Relative to the rigid seat, the cushion increased lateral acceleration and roll oscillation at the lower frequencies and also increased discomfort during lateral oscillation (at frequencies less than 0.63 Hz), roll oscillation (at frequencies less than 0.4 Hz), and fully roll-compensated lateral oscillation (at frequencies between 0.315 and 0.5 Hz). The root-sums-of-squares of the frequency-weighted lateral and roll acceleration at the seat surface predicted the greater vibration discomfort when sitting on the cushion. The frequency-dependence of the predicted discomfort may be improved by adjusting the frequency weighting for roll acceleration at frequencies between 0.25 and 1.0 Hz. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  9. Effects of rolling/crimping of cover crops on their termination, soil strength and moisture

    USDA-ARS?s Scientific Manuscript database

    Termination of cover crops in conservation systems has been accomplished by rolling down and crimping covers using rollers/crimpers. Three weeks after rolling is typically required to plant a cash crop into residue covers. A common method to speed-up a cover crop termination is application of herbic...

  10. Effect of cold-rolling on the magnettic ttransitions in Au83Fe17

    NASA Astrophysics Data System (ADS)

    Xing Du, Chen; J, Nogues; K, V. Rao; C, E. Violet; R, J. Borg

    1988-03-01

    The temperature dependences of the dynamic-elastic and viscous susceptibilities have been measured for Au83Fe17 after cold-rolling. It is found that cold-rolling reduces the Curie temperature and raises the spin-freezing temperature remarkably. These results can be explained on the basis of the precipitation medel proposed by Borg and Violet.

  11. Effect of Vestibular Impairment on Cerebral Blood Flow Response to Dynamic Roll Tilt

    NASA Technical Reports Server (NTRS)

    Serrador, J. M.; Black, F. O.; Schlgel, Todd T.; Lipsitz, L. A.; Wood, S. J.

    2008-01-01

    Change to upright posture results in reductions in cerebral perfusion pressure due to hydrostatic pressure changes related to gravity. Since vestibular organs, specifically the otoliths, provide information on position relative to gravity, vestibular inputs may assist in adaptation to the upright posture. The goal of this study was to examine the effect of direct vestibular stimulation on cerebral blood flow (CBF). To examine the role of otolith inputs we screened 165 subjects for vestibular function and classified subjects as either normal or impaired based on ocular torsion. Ocular torsion, an indication of otolith function, was assessed during sinusoidal roll tilt of 20 degrees at 0.01 Hz (100 sec per cycle). Subjects with torsion one SD below the mean were classified as impaired while subjects one SD above the mean were considered normal. During one session subjects were placed in a chair that was sinusoidally rotated 25 degrees in the roll plane at five frequencies: 0.25 & 0.125 Hz for 80 sec, 0.0625 Hz for 160 sec and 0.03125 Hz and 0.015625 Hz for 320 sec. During testing, CBF (transcranial Doppler), blood pressure (Finapres), and end tidal CO2 (Puritan Bennet) were measured continuously. Ocular torsion was assessed from infrared images of the eyes. All rotations were done in the dark with subjects fixated on a red LED directly at the center of rotation. In the normal group, dynamic tilt resulted in significant changes in both blood pressure and cerebral blood flow velocity that was related to the frequency of stimulus. In contrast the impaired group did not show similar patterns. As expected normal subjects demonstrated significant ocular torsion that was related to stimulus frequency while impaired subjects had minimal changes. These data suggest that vestibular inputs have direct effects on cerebral blood flow regulation during dynamic tilt. Supported by NASA.

  12. Effect of Vestibular Impairment on Cerebral Blood Flow Response to Dynamic Roll Tilt

    NASA Technical Reports Server (NTRS)

    Serrador, J. M.; Black, F. O.; Schlgel, Todd T.; Lipsitz, L. A.; Wood, S. J.

    2008-01-01

    Change to upright posture results in reductions in cerebral perfusion pressure due to hydrostatic pressure changes related to gravity. Since vestibular organs, specifically the otoliths, provide information on position relative to gravity, vestibular inputs may assist in adaptation to the upright posture. The goal of this study was to examine the effect of direct vestibular stimulation on cerebral blood flow (CBF). To examine the role of otolith inputs we screened 165 subjects for vestibular function and classified subjects as either normal or impaired based on ocular torsion. Ocular torsion, an indication of otolith function, was assessed during sinusoidal roll tilt of 20 degrees at 0.01 Hz (100 sec per cycle). Subjects with torsion one SD below the mean were classified as impaired while subjects one SD above the mean were considered normal. During one session subjects were placed in a chair that was sinusoidally rotated 25 degrees in the roll plane at five frequencies: 0.25 & 0.125 Hz for 80 sec, 0.0625 Hz for 160 sec and 0.03125 Hz and 0.015625 Hz for 320 sec. During testing, CBF (transcranial Doppler), blood pressure (Finapres), and end tidal CO2 (Puritan Bennet) were measured continuously. Ocular torsion was assessed from infrared images of the eyes. All rotations were done in the dark with subjects fixated on a red LED directly at the center of rotation. In the normal group, dynamic tilt resulted in significant changes in both blood pressure and cerebral blood flow velocity that was related to the frequency of stimulus. In contrast the impaired group did not show similar patterns. As expected normal subjects demonstrated significant ocular torsion that was related to stimulus frequency while impaired subjects had minimal changes. These data suggest that vestibular inputs have direct effects on cerebral blood flow regulation during dynamic tilt. Supported by NASA.

  13. Effect of Asymmetric Rolling on Plastic Anisotropy of Low Carbon Steels during Simple Shear Tests

    SciTech Connect

    Gracio, J. J.; Vincze, G.; Panigrahi, B. B.; Kim, H. J.; Barlat, F.; Rauch, E. F.; Yoon, J. W.

    2010-06-15

    Simple shear tests are performed on low carbon steel pre-deformed in conventional, asymmetric and orthogonal-asymmetric rolling. The simple-shear tests were carried out at 0 deg. , 45 deg. and 135 deg. with respect to the previous rolling direction. For a reduction ratio of 15%, a transient stagnation in the hardening rate is observed at reloading for all changes in strain path. The shear stress level, the hardening rate and extent of the plateau appear to be insensitive to the preliminary applied rolling conditions. After a reduction ratio of 50%, plastic instability was detected at reloading for all the changes of strain path and rolling conditions studied. A specific heat treatment was then designed allowing the material to become ductile after rolling while retaining the fine microstructure and therefore the high strength. Promising results were obtained essentially for 45 deg. shear tests.

  14. Investigation of thermomechanical behavior of a work roll and of roll life in hot strip rolling

    NASA Astrophysics Data System (ADS)

    Sun, C. G.; Hwang, S. M.; Yun, C. S.; Chung, J. S.

    1998-09-01

    An integrated finite element-based model is presented for the prediction of the steady-state thermomechanical behavior of the roll-strip system and of roll life in hot strip rolling. The model is comprised of basic finite-element models, which are incorporated into an iterative-solution procedure to deal with the interdependence between the thermomechanical behavior of the strip and that of the work roll, which arises from roll-strip contact, as well as with the interdependence between the thermal and mechanical behavior. Comparison is made between the predictions and the measurements to assess solution accuracy. Then, the effect of various process parameters on the detailed aspects of thermomechanical behavior of the work roll and on roll life is investigated via a series of process simulations.

  15. Effects of warm temper rolling on microstructure, texture and magnetic properties of strip-casting 6.5 wt% Si electrical steel

    NASA Astrophysics Data System (ADS)

    Li, Hao-Ze; Liu, Hai-Tao; Liu, Yi; Liu, Zhen-Yu; Cao, Guang-Ming; Luo, Zhong-Han; Zhang, Feng-Quan; Chen, Sheng-Lin; Lyu, Li; Wang, Guo-Dong

    2014-12-01

    6.5 wt% Si electrical steel thin sheets were produced by a processing route including strip casting, hot rolling, warm rolling, intermediate annealing, warm temper rolling and final annealing, in which the warm temper rolling reduction varied from 2.7% to 14.4%. A detailed study of the microstructural and textural evolutions through the whole processing route was carried out by optical microscopy, X-ray diffraction and electron backscattered diffraction analysis. The findings revealed that the final recrystallization microstructure, texture and magnetic properties relied heavily on the warm temper rolling reduction. As the warm temper rolling reduction increased from 2.7% to 14.4%, the finally recrystallized microstructures were more homogeneous and the average grain size was decreased. At the warm temper rolling reduction lower than 7.0%, the occurrence of the exaggeratedly large annealing grains which dominated the whole sheet thickness resulted in strong <001>//ND fiber, parallel α-fiber, <111>//ND fiber and many other strong hard-magnetization texture components. By contrast, at the warm temper rolling reduction higher than 7.0%, the recrystallization textures were characterized by weak <001>//ND fiber, parallel α-fiber, <111>//ND texture, together with fewer and weak hard-magnetization texture components. The mechanism responsible for the finally microstructural and textural changes was explained by strain induced boundary migration. As warm temper rolling reduction increased, the magnetic properties at high frequency were gradually improved due to smaller grain sizes and more desirable textures. The highest magnetic inductions of 1.383 T (B8), 1.484 T (B25) and 1.571 T (B50) in combination with the lowest iron losses at high frequencies of 19.11 W/Kg (W10/400) and 3.824 W/Kg (W2/1000) were obtained at 14.4% warm temper rolling reduction under the applied condition.

  16. Small Class Size and Its Effects.

    ERIC Educational Resources Information Center

    Biddle, Bruce J.; Berliner, David C.

    2002-01-01

    Describes several prominent early grades small-class-size projects and their effects on student achievement: Indiana's Project Prime Time, Tennessee's Project STAR (Student/Teacher Achievement Ratio), Wisconsin's SAGE (Student Achievement Guarantee in Education) Program, and the California class-size-reduction program. Lists several conclusions,…

  17. One-zone rolling of composite materials

    NASA Astrophysics Data System (ADS)

    Kokhan, L. S.; Morozov, Yu. A.; Slavgorodskaya, Yu. B.

    2016-12-01

    The energy-force parameters of free rolling of a strip without its tension and rolling with one backward or forward creep zone in the deformation zone are compared. The limiting backward or forward tensions are determined, and the change in the linear sizes of a composite billet during deformation in a rolling mill is considered.

  18. Effects of terminating cover crops with rolling/crimping and herbicides in a cotton no-till system

    USDA-ARS?s Scientific Manuscript database

    In fall of 2008, a field experiment was initiated in central Alabama to study the effects of rolling/crimping and different herbicides with different application rates on cover crops termination rates, cotton population and yield. Results from 2009 and 2010 growing seasons are presented. A roller/cr...

  19. Wobbly strings: calculating the capture rate of a webcam using the rolling shutter effect in a guitar

    NASA Astrophysics Data System (ADS)

    Cunnah, David

    2014-07-01

    In this paper I propose a method of calculating the time between line captures in a standard complementary metal-oxide-semiconductor (CMOS) webcam using the rolling shutter effect when filming a guitar. The exercise links the concepts of wavelength and frequency, while outlining the basic operation of a CMOS camera through vertical line capture.

  20. The Effect of Prosthetic Ankle Units on Roll-Over Shape Characteristics During Walking in Persons with Bilateral Transtibial Amputations

    PubMed Central

    Gard, Steven A.; Su, Po-Fu; Lipschutz, Robert D.; Hansen, Andrew H.

    2015-01-01

    Some important functions of walking are adversely affected or eliminated in prosthesis users due to reduced or absent ankle motion. The purpose of this retrospective data analysis was to determine the effect of prosthetic ankle units on the characteristics of the ankle-foot roll-over shape in persons with bilateral transtibial amputations. Seventeen subjects were fitted with Endolite Multiflex Ankles to provide ankle plantar/dorsiflexion during the stance phase of gait. Two quantitative gait analyses were performed as subjects walked with (1) Seattle Lightfoot II feet (baseline condition) and (2) with the prosthetic ankle units added. Roll-over shape radii and effective foot length ratio were calculated and compared for the two prosthetic configurations. When subjects walked with the ankle units, ankle motion increased (p<0.001), peak ankle plantarflexion moment during stance decreased slightly, and ankle-foot roll-over shape radii were significantly less (p<0.001) compared to the baseline condition. The effective foot length ratio of the roll-over shape was found to increase with walking speed (p<0.001), but it was not significantly affected by the prosthetic ankle units (p=0.066). Prosthetists and manufacturers are encouraged to consider the effect of combining prosthetic components on the overall characteristics of the prosthesis and the functions they impart to the user. PMID:22234709

  1. Wobbly Strings: Calculating the Capture Rate of a Webcam Using the Rolling Shutter Effect in a Guitar

    ERIC Educational Resources Information Center

    Cunnah, David

    2014-01-01

    In this paper I propose a method of calculating the time between line captures in a standard complementary metal-oxide-semiconductor (CMOS) webcam using the rolling shutter effect when filming a guitar. The exercise links the concepts of wavelength and frequency, while outlining the basic operation of a CMOS camera through vertical line capture.

  2. Wobbly Strings: Calculating the Capture Rate of a Webcam Using the Rolling Shutter Effect in a Guitar

    ERIC Educational Resources Information Center

    Cunnah, David

    2014-01-01

    In this paper I propose a method of calculating the time between line captures in a standard complementary metal-oxide-semiconductor (CMOS) webcam using the rolling shutter effect when filming a guitar. The exercise links the concepts of wavelength and frequency, while outlining the basic operation of a CMOS camera through vertical line capture.

  3. Effect of fiber fractions of prickly pear cactus (nopal) on quality and sensory properties of wheat bread rolls.

    PubMed

    Guevara-Arauza, Juan Carlos; Bárcenas, Diego Guadalupe; Ortega-Rivas, Enrique; Martínez, Jaime David Pérez; Hernández, Jaime Reyes; de Jesús Ornelas-Paz, José

    2015-05-01

    In this study the addition of total fiber (TF), insoluble fiber (IF), and soluble fiber (SF) from nopal to wheat flour used to make bread rolls was assessed. The rheological properties of dough as well as quality, texture, sensorial and physical characteristics of the crumb rolls produced were evaluated. The storage (23.50 MPa) and loss modulus (11.95 MPa) for SF-dough were the lowest indicating that a less visco-elastic behavior was obtained. Polarized light microscopy showed that a more homogeneous size and a better distribution of starch granules were developed into SF-dough. Crumb hardness (3.25-4.78 N) and chewiness (0.31-0.81 N) of SF-rolls were lower than the control experiment (3.99-5.81 N and 0.35-1.01 N respectively). Springiness for all treatments was constant (1.0) compared with the control (1.02-0.87) for 2 days of storage. The lowest cohesiveness values (0.24-014) were computed by IF treatment for a similar storage time. The specific crumb volume increased by 12.46, 9.03 and 1.10 % by the addition of SF, TF and IF respectively. The lowest rate of staling was shown by SF-rolls (0.199) and it was followed by TF (0.296), IF (0.381) and control (0.458) treatments. As a result, the highest scores on quality (9.3 out of 10) and sensorial attributes (from 8.9 up to 9.7) were assigned to SF-rolls.

  4. Acute Effects of Lateral Thigh Foam Rolling on Arterial Tissue Perfusion Determined by Spectral Doppler and Power Doppler Ultrasound.

    PubMed

    Hotfiel, Thilo; Swoboda, Bernd; Krinner, Sebastian; Grim, Casper; Engelhardt, Martin; Uder, Michael; Heiss, Rafael U

    2017-04-01

    Hotfiel, T, Swoboda, B, Krinner, S, Grim, C, Engelhardt, M, Uder, M, and Heiss, R. Acute effects of lateral thigh foam rolling on arterial tissue perfusion determined by spectral Doppler and power Doppler ultrasound. J Strength Cond Res 31(4): 893-900, 2017-Foam rolling has been developed as a popular intervention in training and rehabilitation. However, evidence on its effects on the cellular and physiological level is lacking. The aim of this study was to assess the effect of foam rolling on arterial blood flow of the lateral thigh. Twenty-one healthy participants (age, 25 ± 2 years; height, 177 ± 9 cm; body weight, 74 ± 9 kg) were recruited from the medical and sports faculty. Arterial tissue perfusion was determined by spectral Doppler and power Doppler ultrasound, represented as peak flow (Vmax), time average velocity maximum (TAMx), time average velocity mean (TAMn), and resistive index (RI), and with semiquantitative grading that was assessed by 4 blindfolded investigators. Measurement values were assessed under resting conditions and twice after foam rolling exercises of the lateral thigh (0 and 30 minutes after intervention). The trochanteric region, mid portion, and distal tibial insertion of the lateral thigh were representative for data analysis. Arterial blood flow of the lateral thigh increased significantly after foam rolling exercises compared with baseline (p ≤ 0.05). We detected a relative increase in Vmax of 73.6% (0 minutes) and 52.7% (30 minutes) (p < 0.001), in TAMx of 53.2% (p < 0.001) and 38.3% (p = 0.002), and in TAMn of 84.4% (p < 0.001) and 68.2% (p < 0.001). Semiquantitative power Doppler scores at all portions revealed increased average grading of 1.96 after intervention and 2.04 after 30 minutes compared with 0.75 at baseline. Our results may contribute to the understanding of local physiological reactions to self-myofascial release.

  5. The effect of dispersoid particle size on the superplasticity of Al-Mg alloy

    SciTech Connect

    Chanda, T.; Ghosh, A.K.; Lavender, C.

    1995-12-31

    An Al-Mg alloy containing dispersoid forming elements such as Mn, Cr and Zr was thermomechanically processed with variations in processing history to produce nearly the same grain size ({approximately}6 {micro}m), but different distribution of size and density of intermetallic particles. Mechanical response of these materials were studied within the superplastic deformation regime in terms of stress-strain, stress-strain rate characteristics, cavitation and grain growth, and superplastic tensile elongation. In this work particles of approximately 500 nm size have been found to cause grain refinement after 90% rolling reduction contrary to previous findings of 2 {micro}m particles in an Al-0.45% Cu alloy. Particles with 200 to 500 nm size favorably influence superplastic elongation, but particle sizes in the range of 600 to 900 nm appear to have adverse effect in terms of superplastic flow properties, due to excessive cavitation.

  6. Effects of roll visual motion on online control of arm movement: reaching within a dynamic virtual environment

    PubMed Central

    Kenyon, Robert V.; Keshner, Emily A.

    2009-01-01

    . Furthermore, the reaching movement was affected differentially by the direction of roll motion. Subjects demonstrated a stronger effect of visual motion on movements taking place in the direction of visual roll (e.g., leftward movements during counterclockwise roll). Further investigation of the hand path revealed significant changes during roll motion for both the area and shape of the 95% tolerance ellipses that were constructed from the hand position following the main movement termination. These changes corresponded with a hand drift that would suggest that subjects were relying more on proprioceptive information to estimate the arm position in space during roll motion of the visual field. We conclude that both the spatial and temporal kinematics of the reach movement were affected by the motion of the visual field, suggesting interference with the ability to simultaneously process two consecutive stimuli. PMID:18936925

  7. The effects of closed loop tracking on a subjective tilt threshold in the roll axis

    NASA Technical Reports Server (NTRS)

    Roark, M.; Junker, A. M.

    1978-01-01

    The indifference thresholds for the perception of tilt in the roll axis were experimentally determined in a moving base simulator under three tracking task difficulties. The threshold level determined in this experiment is approximately 5 to 7 degrees (.lg).

  8. Study on edge crack propagation during cold rolling of thin strip by FEM

    NASA Astrophysics Data System (ADS)

    Xie, H. B.; Jiang, Z. Y.; Wei, D. B.; Tieu, A. K.

    2010-06-01

    Edge crack is one common phenomenon in cold rolling of thin strip which affects qualities of the rolled strip. A three-dimensional elastic-plastic finite element (FE) model for cold flat product rolling has been developed to simulate the edge crack propagation during rolling. Stress field is investigated around the edge crack tip, and the effects of the friction coefficient, the initial crack size, reductions on crack propagation are analysed. The FE simulation provides a better understanding of the crack growth at the edge of thin strip, and could be helpful in developing of cold rolled strip with high performance mechanical properties. The optimum condition to eliminate defects is discussed, and the proposed prediction method of surface defect can be utilised to make defect free products in rolling processes.

  9. Mixed convective/dynamic roll vortices and their effects on initial wind and temperature profiles

    NASA Technical Reports Server (NTRS)

    Haack, Tracy; Shirer, Hampton N.

    1991-01-01

    The onset and development of both dynamically and convectively forced boundary layer rolls are studied with linear and nonlinear analyses of a truncated spectral model of shallow Boussinesq flow. Emphasis is given here on the energetics of the dominant roll modes, on the magnitudes of the roll-induced modifications of the initial basic state wind and temperature profiles, and on the sensitivity of the linear stability results to the use of modified profiles as basic states. It is demonstrated that the roll circulations can produce substantial changes to the cross-roll component of the initial wind profile and that significant changes in orientation angle estimates can result from use of a roll-modified profile in the stability analysis. These results demonstrate that roll contributions must be removed from observed background wind profiles before using them to investigate the mechanisms underlying actual secondary flows in the boundary layer. The model is developed quite generally to accept arbitrary basic state wind profiles as dynamic forcing. An Ekman profile is chosen here merely to provide a means for easy comparison with other theoretical boundary layer studies; the ultimate application of the model is to study observed boundary layer profiles. Results of the analytic stability analysis are validated by comparing them with results from a larger linear model. For an appropriate Ekman depth, a complete set of transition curves is given in forcing parameter space for roll modes driven both thermally and dynamically. Preferred orientation angles, horizontal wavelengths and propagation frequencies, as well as energetics and wind profile modifications, are all shown to agree rather well with results from studies on Ekman layers as well as with studies on near-neutral and convective atmospheric boundary layers.

  10. Quantum-gravitational effects on gauge-invariant scalar and tensor perturbations during inflation: The slow-roll approximation

    NASA Astrophysics Data System (ADS)

    Brizuela, David; Kiefer, Claus; Krämer, Manuel

    2016-12-01

    We continue our study on corrections from canonical quantum gravity to the power spectra of gauge-invariant inflationary scalar and tensor perturbations. A direct canonical quantization of a perturbed inflationary universe model is implemented, which leads to a Wheeler-DeWitt equation. For this equation, a semiclassical approximation is applied in order to obtain a Schrödinger equation with quantum-gravitational correction terms, from which we calculate the corrections to the power spectra. We go beyond the de Sitter case discussed earlier and analyze our model in the first slow-roll approximation, considering terms linear in the slow-roll parameters. We find that the dominant correction term from the de Sitter case, which leads to an enhancement of power on the largest scales, gets modified by terms proportional to the slow-roll parameters. A correction to the tensor-to-scalar ratio is also found at second order in the slow-roll parameters. Making use of the available experimental data, the magnitude of these quantum-gravitational corrections is estimated. Finally, the effects for the temperature anisotropies in the cosmic microwave background are qualitatively obtained.

  11. Effects of Particulate Debris Morphology on the Rolling Wear Behavior of All-Steel and Si(Sub 3)N(Sub 4)-Steel Bearing Element Couples

    SciTech Connect

    Adair, J.H.; Mecholsky, J.J., Jr.; Mitchell, D.J.

    1999-01-25

    Rolling contact fatigue experiments were performed on all-steel and hybrid Si{sub 3}N{sub 4}-M50 steel rolling bearing systems using particulate contaminated lubricants. The particulate contaminants used were glycothermally synthesized {alpha}-Al{sub 2}O{sub 3} platelets or Arizona test dust. The effects of contaminant composition and morphology on rolling contact fatigue and wear behavior were explored. The effects of bearing element material properties on fatigue and wear behavior were also examined. Rolling wear behavior is related to bearing component material configuration and the type of particulate contaminant present in the lubricant. Component and particulate material properties such as hardness and elastic modulus are observed to affect rolling wear behavior. Wear mechanisms such as contact stress fatigue, indenting, cutting and plowing are observed.

  12. Scuffing Characteristics of High-Load Rolling/Sliding Contacts Operating in Liquid Oxygen: Effects of Materials and Surface Roughness

    NASA Technical Reports Server (NTRS)

    Chang, L.; Hall, P. B.; Thom, R.

    1996-01-01

    This research reports on an experimental study of the effects of materials and surface roughness on the scuffing characteristics of rolling/sliding contacts cooled and lubricated with liquid oxygen. Experiments were carried out under heavy loading with a Hertzian pressure in the range of 2.0 GPa to 3.0 GPa and with a high rolling velocity of up to 48 m/s. For contacts between AISI 440 C stainless-steel elements, the results showed that the scuffing behavior of the system was fairly consistent under a wide range of rolling velocity. Scuffing commenced at a small slide-to-roll ratio of around 0.02, and the scuffing behavior of the contact was not sensitive to surface roughness for the test-sample RMS roughness ranging from 0.02 microns to 0.10 microns. For contacts between 440 C and Si3N4 elements, on the other hand, the scuffing behavior of the system was not very consistent and somewhat unpredictable. The results were sensitive to surface roughness particularly that of the Si3N4 test sample. With well polished test samples, consistent results were obtained; the level of traction was lower than that with a 440 C toroid and scuffing did not take place up to a slide-to-roll ratio of near 0.03. The results strongly suggest that significant hydrodynamic effect can be generated by liquid oxygen under heavy loading and high velocity conditions. The results also suggest that the hydrodynamic action is likely generated by the conventional viscous mechanism as it can be largely destroyed by a narrow circumferential surface scratch running through the central region of the contact.

  13. Size scale effect in cavitation erosion

    NASA Technical Reports Server (NTRS)

    Rao, P. V.; Rao, B. C.; Buckley, D. H.

    1982-01-01

    An overview and data analyses pertaining to cavitation erosion size scale effects are presented. The exponents n in the power law relationship are found to vary from 1.7 to 4.9 for venturi and rotating disk devices supporting the values reported in the literature. Suggestions for future studies were made to arrive at further true scale effects.

  14. Statistical Aspects of Effect Size Estimation.

    ERIC Educational Resources Information Center

    Hedges, Larry V.

    When the results of a series of independent studies are combined, it is useful to quantitatively estimate the magnitude of the effects. Several methods for estimating effect size are compared in this paper. Glass' estimator and the uniformly minimum variance unbiased estimator are based on the ratio of the sample mean difference and the pooled…

  15. Rolling Uphill

    ERIC Educational Resources Information Center

    Cross, Rod

    2017-01-01

    In a recent letter to this journal, Mungan noted that translational energy can be converted into gravitational potential energy when an object is projected vertically, but rotational energy is not usually converted in this manner. As an exception, he gave an example where "a ball initially rolling without slipping will travel higher up a…

  16. Understanding the effect size and its measures

    PubMed Central

    Ialongo, Cristiano

    2016-01-01

    The evidence based medicine paradigm demands scientific reliability, but modern research seems to overlook it sometimes. The power analysis represents a way to show the meaningfulness of findings, regardless to the emphasized aspect of statistical significance. Within this statistical framework, the estimation of the effect size represents a means to show the relevance of the evidences produced through research. In this regard, this paper presents and discusses the main procedures to estimate the size of an effect with respect to the specific statistical test used for hypothesis testing. Thus, this work can be seen as an introduction and a guide for the reader interested in the use of effect size estimation for its scientific endeavour. PMID:27346958

  17. Detecting past changes of effective population size

    PubMed Central

    Nikolic, Natacha; Chevalet, Claude

    2014-01-01

    Understanding and predicting population abundance is a major challenge confronting scientists. Several genetic models have been developed using microsatellite markers to estimate the present and ancestral effective population sizes. However, to get an overview on the evolution of population requires that past fluctuation of population size be traceable. To address the question, we developed a new model estimating the past changes of effective population size from microsatellite by resolving coalescence theory and using approximate likelihoods in a Monte Carlo Markov Chain approach. The efficiency of the model and its sensitivity to gene flow and to assumptions on the mutational process were checked using simulated data and analysis. The model was found especially useful to provide evidence of transient changes of population size in the past. The times at which some past demographic events cannot be detected because they are too ancient and the risk that gene flow may suggest the false detection of a bottleneck are discussed considering the distribution of coalescence times. The method was applied on real data sets from several Atlantic salmon populations. The method called VarEff (Variation of Effective size) was implemented in the R package VarEff and is made available at https://qgsp.jouy.inra.fr and at http://cran.r-project.org/web/packages/VarEff. PMID:25067949

  18. Detecting past changes of effective population size.

    PubMed

    Nikolic, Natacha; Chevalet, Claude

    2014-06-01

    Understanding and predicting population abundance is a major challenge confronting scientists. Several genetic models have been developed using microsatellite markers to estimate the present and ancestral effective population sizes. However, to get an overview on the evolution of population requires that past fluctuation of population size be traceable. To address the question, we developed a new model estimating the past changes of effective population size from microsatellite by resolving coalescence theory and using approximate likelihoods in a Monte Carlo Markov Chain approach. The efficiency of the model and its sensitivity to gene flow and to assumptions on the mutational process were checked using simulated data and analysis. The model was found especially useful to provide evidence of transient changes of population size in the past. The times at which some past demographic events cannot be detected because they are too ancient and the risk that gene flow may suggest the false detection of a bottleneck are discussed considering the distribution of coalescence times. The method was applied on real data sets from several Atlantic salmon populations. The method called VarEff (Variation of Effective size) was implemented in the R package VarEff and is made available at https://qgsp.jouy.inra.fr and at http://cran.r-project.org/web/packages/VarEff.

  19. Investigation of the effects of bandwidth and time delay on helicopter roll-axis handling qualities

    NASA Technical Reports Server (NTRS)

    Pausder, Heinz-Juergen; Blanken, Chris L.

    1993-01-01

    Several years of cooperative research conducted under the U.S./German Memorandum of Understanding (MOU) in helicopter flight control has recently resulted in a successful handling qualities study. The focus of this cooperative research has been the effects on handling qualities due to time delays in combination with a high bandwidth vehicle. The jointly performed study included the use of U.S. ground-based simulation and German in-flight simulation facilities. The NASA-Ames Vertical Motion Simulator (VMS) was used to develop a high bandwidth slalom tracking task which took into consideration the constraints of the facilities. The VMS was also used to define a range of the test parameters and to perform initial handling qualities evaluations. The flight tests were conducted using DLR's variable-stability BO 105 S3 Advanced Technology Testing Helicopter System (ATTHeS). Configurations included a rate command and an attitude command response system with added time delays up to 160 milliseconds over the baseline and bandwidth values between 1.5 and 4.5 rad/sec. Sixty-six evaluations were performed in about 25 hours of flight time during ten days of testing. The results indicate a need to more tightly constrain the allowable roll axis phase delay for the Level 1 and Level 2 requirements in the U.S. Army's specification for helicopter handling qualities, ADS-33C.

  20. Sensory crispness of crispy rolls: effect of formulation, storage conditions, and water distribution in the crust.

    PubMed

    Primo-Martín, C; Van Vliet, T

    2009-10-01

    Crispness is an important sensory quality parameter that strongly influences the acceptability of cellular solid foods such as the crust of many types of breads. Crispness of the bread crust depends particularly on its water content. In this study, the relationship between sensory crispness of crispy rolls and the average water content of the crust was studied for different bread formulations (control, amylase, glucose-oxidase, and protease) and storage conditions (40% and 80% RH). From the different formulations used, only protease treatment increased the crispness of the crust and its retention at both storage conditions. The positive effect of the protease treatment was due to a lower water content of the crust of these breads compared to the other formulations. The relationship between sensory attributes, formulation, and storage conditions was found to be dominated by the dependence on storage conditions. When combining data for low and high humidity storage it showed that crusts with equal water contents could exhibit different scores for crispness. The results led to the hypothesis that a gradient of water content exists within the crust. At high humidity, the crust will take up water from both crumb and environment and a relative smaller gradient of water will exist within the crust. At low humidity on the other hand, the crust will take up water from the crumb only, resulting in a larger gradient of water within the crust.

  1. The Effective Size of a Subdivided Population

    PubMed Central

    Whitlock, M. C.; Barton, N. H.

    1997-01-01

    This paper derives the long-term effective size, N(e), for a general model of population subdivision, allowing for differential deme fitness, variable emigration and immigration rates, extinction, colonization, and correlations across generations in these processes. We show that various long-term measures of N(e) are equivalent. The effective size of a metapopulation can be expressed in a variety of ways. At a demographic equilibrium, N(e) can be derived from the demography by combining information about the ultimate contribution of each deme to the future genetic make-up of the population and Wright's F(ST)'s. The effective size is given by N(e) = 1/(1 + var ( &))<(1 - f(STi))/N(i)n>, where n is the number of demes, &(i) is the eventual contribution of individuals in deme i to the whole population (scaled such that σ(i) &(i) = n), and < > denotes an average weighted by &(i)(2). This formula is applied to a catastrophic extinction model (where sites are either empty or at carrying capacity) and to a metapopulation model with explicit dynamics, where extinction is caused by demographic stochasticity and by chaos. Contrary to the expectation from the standard island model, the usual effect of population subdivision is to decrease the effective size relative to a panmictic population living on the same resource. PMID:9136031

  2. Fundamental phenomena governing heat transfer during rolling

    NASA Astrophysics Data System (ADS)

    Chen, W. C.; Samarasekera, I. V.; Hawbolt, E. B.

    1993-06-01

    To quantify the effect of roll chilling on the thermal history of a slab during hot rolling, tests were conducted at the Canada Center for Mineral and Energy Technology (CANMET) and at the University of British Columbia (UBC). In these tests, the surface and the interior temperatures of specimens were recorded during rolling using a data acquisition system. The corresponding heat-transfer coefficients in the roll bite were back-calculated by a trial-and-error method using a heat-transfer model. The heat-transfer coefficient was found to increase along the arc of contact and reach a maximum, followed by a decrease, until the exit of the roll bite. Its value was influenced by rolling parameters, such as percent reduction, rolling speed, rolling temperature, material type, etc. It was shown that the heat-transfer coefficient in the roll gap was strongly dependent on the roll pressure, and the effect of different variables on the interfacial heat-transfer coefficient can be related to their influence on pressure. At low mean roll pressure, such as in the case of rolling plain carbon steels at elevated temperature, the maximum heat-transfer coefficient in the roll bite was in the 25 to 35 kW/m2 °C range. As the roll pressure increased with lower rolling temperature and higher deformation resistance of stainless steel and microalloyed grades, the maximum heat-transfer coefficient reached a value of 620 kW/m2 °C. Obviously, the high pressure improved the contact between the roll and the slab surface, thereby reducing the resistance to heat flow. The mean roll-gap heat-transfer coefficient at the interface was shown to be linearly related to mean roll pressure. This finding is important because it permitted a determination of heat-transfer coefficients applicable to industrial rolling from pilot mill data. Thus, the thermal history of a slab during rough rolling was computed using a model in which the mean heat-transfer coefficient between the roll and the slab was

  3. Effects of oxide layers on surface defects during hot rolling processes

    NASA Astrophysics Data System (ADS)

    Min, Kyungzoon; Kim, Kisoo; Kim, Sung Kyu; Lee, Doh-Jae

    2012-04-01

    An oxide layer, which developed on the surface of a commercial hot rolling mill, was examined by forcibly stopping the roller between mill stands during activity. Liquid quartz was sprayed on the strip to prevent further oxide layer growth during cooling after stopping the hot-rolling mills. Then the thickness and shape of the oxide layer was examined in a cross-sectional view using an optical microscope. The thickness of the oxide layer increased through the 1st and 2nd passes of hot rolling, and then decreased through successive rolling, because the thickening rate by growth is larger than the thinning rate by deformation in high temperature. The temperature distributions of the oxide layer as well as the strip were predicted using the thermo-mechanical finite element method. As thermal conductivity of the oxide layer is low, the temperature deviation of the oxide layer increases and average temperature decreases as the thickness of the oxide layer increases, suggesting the increased formation of surface defects. With these results, a new cooling device was installed between the hot rolling mills to decrease the surface temperature and the thickness of the oxide layer, resulting in improved surface quality of the strip.

  4. Effect of a nonconstant C/m-alpha/ on the stability of rolling aircraft

    NASA Technical Reports Server (NTRS)

    Davari, B.; Laitone, E. V.

    1977-01-01

    An analytical study is carried out of the behavior of modern high-speed aircraft of inertially slender configurations in maneuvers involving large rates of roll. Inertia cross-coupling, as well as a linear variation of longitudinal static stability (C/m-alpha/) with angle of attack, are considered. The steady-state solutions of the nonlinear equations of motion, based on principal inertia axes, are studied to obtain useful information on the response behavior of the state variables during roll maneuvers. It is shown that, in addition to the critical values of aileron deflection that have been previously found to limit a steady-state roll with constant longitudinal static stability, there can be two new critical values introduced by a linear decrease of the absolute value of longitudinal static stability with angle of attack. For aileron deflections near these critical values, the response of the aircraft exhibits violent oscillations and dangerous peak loads, due to the cross-coupled motion accompanying a roll maneuver. These critical values define a new range of aileron deflections in which no steady-state roll is possible.

  5. Convective heat processing of turkey roll: effects on sensory quality and energy usage.

    PubMed

    Brown, N E; Chyuan, J Y

    1987-11-01

    Twenty-four frozen, raw, boneless, ready-to-cook turkey rolls were cooked in an institutional electric convection oven to an internal temperature of 77 degrees C. Six treatment combinations of three cooking temperatures (105 degrees C, 135 degrees C, and 165 degrees C) and two holding conditions (not chilled and chilled for 24 hours) were studied. Turkey rolls from each treatment combination were subjected to three hot-holding times (0, 60, and 120 minutes). Electrical energy usage was monitored during heat processing of the turkey rolls, reheating the turkey slices, and hot holding the turkey slices. Aroma, juicy mouthfeel, texture, flavor, and flavor off-notes of the cooked turkey were evaluated by seven judges using 150-mm unstructured line scales. Chew counts also were recorded. Turkey cooked at 105 degrees C took significantly more time to cook (331 vs. 227 and 203 minutes) but consumed significantly less energy (3.4 vs. 3.8 and 4.5 kWh) than turkey rolls cooked at 135 degrees C and 165 degrees C, respectively. Significantly higher juicy mouthfeel scores were obtained when the turkey roll was cooked in the convection oven at an oven temperature of 105 degrees C, the turkey was not chilled, and the slices were held hot for 60 minutes or less.

  6. Modeling recrystallization kinetics during strip rolling

    SciTech Connect

    Sun, W.P.; Hawbolt, E.B.; Meadowcroft, T.R.

    1995-01-01

    In order to simulate the microstructural evolution during hot strip rolling, double-hit compression tests have been carried out on plain carbon steels. Using the softening data obtained by these tests, mathematical models were developed to predict the overall kinetics of static recrystallization under roughing and finishing mill conditions. These models include the effects of deformation temperature, applied strain, strain rate and initial austenite grain size. Predictions based on these models are in reasonable agreement with the present experimental results.

  7. Effect of Cold Rolling on the Coffin Manson Relationship in Low-Cycle Fatigue of Superalloy IN718

    NASA Astrophysics Data System (ADS)

    Praveen, K. V. U.; Singh, Vakil

    2008-01-01

    The age-hardenable Ni-Fe based superalloy IN718 exhibits a dual-slope Coffin Manson (C-M) relationship during low-cycle fatigue (LCF). Effort was made to eliminate the dual-slope C-M relationship by introducing prior deformation. Peak-aged (PA) material was subjected to different degrees of cold reduction, and its LCF behavior was examined. Cold rolling is found to be highly effective in eliminating the dual slope and enhancing the fatigue life at low strain amplitudes. Cold rolling coupled with stress relieving (SR) treatment is found to further improve the fatigue life. The role of texture on the observed LCF behavior is analyzed and found to have no significant effect.

  8. Disruption effects on the beam size measurement

    SciTech Connect

    Raimondi, P.; Decker, F.J.; Chen, P.

    1995-06-01

    At the SLC Final Focus with higher currents and smaller beam sizes, the disruption parameter D{sub y} is close to one and so the pinch effect should produce a luminosity enhancement. Since a flat beam-beam function is fit to deflection scan data to measure the beam size, disruption can affect the measurement. Here the authors discuss the quantitative effects of disruption for typical SLC beam parameters. With 3.5 10{sup 10} particles per pulse, bunch length of 0.8 mm and beam sizes of 2.1 {mu}m horizontally and 0.55 {mu}m vertically, the measured vertical size can be as much as 25% bigger than the real one. Furthermore during the collision the spot size actually decrease, producing an enhancement factor H{sub D} of about 1.25. This would yield to a true luminosity which is 1.6 times that which is estimated from the beam-beam deflection fit.

  9. Effect Sizes in Cluster-Randomized Designs

    ERIC Educational Resources Information Center

    Hedges, Larry V.

    2007-01-01

    Multisite research designs involving cluster randomization are becoming increasingly important in educational and behavioral research. Researchers would like to compute effect size indexes based on the standardized mean difference to compare the results of cluster-randomized studies (and corresponding quasi-experiments) with other studies and to…

  10. Effect Size Reporting Practices in Published Articles

    ERIC Educational Resources Information Center

    Alhija, Fadia Nasser-Abu; Levy, Adi

    2009-01-01

    Effect size (ES) reporting practices in a sample of 10 educational research journals are examined in this study. Five of these journals explicitly require reporting ES and the other 5 have no such policy. Data were obtained from 99 articles published in the years 2003 and 2004, in which 183 statistical analyses were conducted. Findings indicate no…

  11. Introducing the Mean Absolute Deviation "Effect" Size

    ERIC Educational Resources Information Center

    Gorard, Stephen

    2015-01-01

    This paper revisits the use of effect sizes in the analysis of experimental and similar results, and reminds readers of the relative advantages of the mean absolute deviation as a measure of variation, as opposed to the more complex standard deviation. The mean absolute deviation is easier to use and understand, and more tolerant of extreme…

  12. Introducing the Mean Absolute Deviation "Effect" Size

    ERIC Educational Resources Information Center

    Gorard, Stephen

    2015-01-01

    This paper revisits the use of effect sizes in the analysis of experimental and similar results, and reminds readers of the relative advantages of the mean absolute deviation as a measure of variation, as opposed to the more complex standard deviation. The mean absolute deviation is easier to use and understand, and more tolerant of extreme…

  13. Effect Sizes in Cluster-Randomized Designs

    ERIC Educational Resources Information Center

    Hedges, Larry V.

    2007-01-01

    Multisite research designs involving cluster randomization are becoming increasingly important in educational and behavioral research. Researchers would like to compute effect size indexes based on the standardized mean difference to compare the results of cluster-randomized studies (and corresponding quasi-experiments) with other studies and to…

  14. Investigations of initiation spot size effects

    SciTech Connect

    Clarke, Steven A; Akinci, Adrian A; Leichty, Gary; Schaffer, Timothy; Murphy, Michael J; Munger, Alan; Thomas, Keith A

    2010-01-01

    As explosive components become smaller, a greater understanding of the effect of initiation spot size on detonation becomes increasingly critical. A series of tests of the effect of initiation spot size will be described. A series of DOI (direct optical initiation) detonators with initiation spots sizes from {approx}50 um to 1000um have been tested to determine laser parameters for threshold firing of low density PETN pressings. Results will be compared with theoretical predictions. Outputs of the initiation source (DOI ablation) have been characterized by a suite of diagnostics including PDV and schlieren imaging. Outputs of complete detonators have been characterized using PDV, streak, and/or schlieren imaging. At present, we have not found the expected change in the threshold energy to spot size relationship for DOI type detonators found in similar earlier for projectiles, slappers and EBWs. New detonators designs (Type C) are currently being tested that will allow the determination of the threshold for spot sizes from 250 um to 105um, where we hope to see change in the threshold vs. spot size relationship. Also, one test of an extremely small diameter spot size (50um) has resulted in preliminary NoGo only results even at energy densities as much as 8 times the energy density of the threshold results presented here. This gives preliminary evidence that 50um spot may be beyond the critical initiation diameter. The constant threshold energy to spot size relationship in the data to date does however still give some insight into the initiation mechanism of DOI detonators. If the DOI initiation mechanism were a 1D mechanism similar to a slapper or a flyer impact, the expected inflection point in the graph would have been between 300um and 500um diameter spot size, within the range of the data presented here. The lack of that inflection point indicates that the DOI initiation mechanism is more likely a 2D mechanism similar to a sphere or rod projectile. We expect to

  15. SPECIFIC AND CROSS-OVER EFFECTS OF FOAM ROLLING ON ANKLE DORSIFLEXION RANGE OF MOTION

    PubMed Central

    Beardsley, Chris

    2016-01-01

    ABSTRACT Background Flexibility is an important physical quality. Self-myofascial release (SMFR) methods such as foam rolling (FR) increase flexibility acutely but how long such increases in range of motion (ROM) last is unclear. Static stretching (SS) also increases flexibility acutely and produces a cross-over effect to contralateral limbs. FR may also produce a cross-over effect to contralateral limbs but this has not yet been identified. Purpose To explore the potential cross-over effect of SMFR by investigating the effects of a FR treatment on the ipsilateral limb of 3 bouts of 30 seconds on changes in ipsilateral and contralateral ankle DF ROM and to assess the time-course of those effects up to 20 minutes post-treatment. Methods A within- and between-subject design was carried out in a convenience sample of 26 subjects, allocated into FR (n=13) and control (CON, n=13) groups. Ankle DF ROM was recorded at baseline with the in-line weight-bearing lunge test for both ipsilateral and contralateral legs and at 0, 5, 10, 15, 20 minutes following either a two-minute seated rest (CON) or 3 3 30 seconds of FR of the plantar flexors of the dominant leg (FR). Repeated measures ANOVA was used to examine differences in ankle DF ROM. Results No significant between-group effect was seen following the intervention. However, a significant within-group effect (p<0.05) in the FR group was seen between baseline and all post-treatment time-points (0, 5, 10, 15 and 20 minutes). Significant within-group effects (p<0.05) were also seen in the ipsilateral leg between baseline and at all post-treatment time-points, and in the contralateral leg up to 10 minutes post-treatment, indicating the presence of a cross-over effect. Conclusions FR improves ankle DF ROM for at least 20 minutes in the ipsilateral limb and up to 10 minutes in the contralateral limb, indicating that FR produces a cross-over effect into the contralateral limb. The mechanism producing these cross-over effects is

  16. Comparison of wing-span averaging effects on lift, rolling moment, and bending moment for two span load distributions and for two turbulence representations

    NASA Technical Reports Server (NTRS)

    Lichtenstein, J. H.

    1978-01-01

    An analytical method of computing the averaging effect of wing-span size on the loading of a wing induced by random turbulence was adapted for use on a digital electronic computer. The turbulence input was assumed to have a Dryden power spectral density. The computations were made for lift, rolling moment, and bending moment for two span load distributions, rectangular and elliptic. Data are presented to show the wing-span averaging effect for wing-span ratios encompassing current airplane sizes. The rectangular wing-span loading showed a slightly greater averaging effect than did the elliptic loading. In the frequency range most bothersome to airplane passengers, the wing-span averaging effect can reduce the normal lift load, and thus the acceleration, by about 7 percent for a typical medium-sized transport. Some calculations were made to evaluate the effect of using a Von Karman turbulence representation. These results showed that using the Von Karman representation generally resulted in a span averaging effect about 3 percent larger.

  17. Effect of foam rolling and static stretching on passive hip-flexion range of motion.

    PubMed

    Mohr, Andrew R; Long, Blaine C; Goad, Carla L

    2014-11-01

    Many athletes report that foam rollers help release tension in their muscles, thus resulting in greater range of motion (ROM) when used before stretching. To date, no investigators have examined foam rollers and static stretching. To determine if foam rolling before static stretching produces a significant change in passive hip-flexion ROM. Controlled laboratory study. Research laboratory. 40 subjects with less than 90° of passive hip-flexion ROM and no lower-extremity injury in the 6 mo before data collection. During each of 6 sessions, subjects' passive hip-flexion ROM was measured before and immediately after static stretching, foam rolling and static stretching, foam rolling, or nothing (control). To minimize accessory movement of the hip and contralateral leg, subjects lay supine with a strap placed across their hip and another strap located over the uninvolved leg just superior to the patella. A bubble inclinometer was then aligned on the thigh of the involved leg, with which subjects then performed hip flexion. Change in passive hip-flexion ROM from the preintervention measure on day 1 to the postintervention measure on day 6. There was a significant change in passive hip-flexion ROM regardless of treatment (F3,17 = 8.06, P = .001). Subjects receiving foam roll and static stretch had a greater change in passive hip-flexion ROM compared with the static-stretch (P = .04), foam-rolling (P = .006), and control (P = .001) groups. Our results support the use of a foam roller in combination with a static-stretching protocol. If time allows and maximal gains in hip-flexion ROM are desired, foam rolling the hamstrings muscle group before static stretching would be appropriate in noninjured subjects who have less than 90° of hamstring ROM.

  18. The effects of egg albumin incorporation on quality attributes of pale, soft, exudative (PSE-like) turkey rolls.

    PubMed

    Öztürk, Burcu; Serdaroğlu, Meltem

    2017-05-01

    Pale, soft, exudative (PSE-like) poultry phenomenon has been a growing problem in meat industry in terms of quality and economic losses, thus data is required to evaluate PSE raw material in product formulations. The aim of our study was to investigate the effects of egg albumin (EA) utilization on quality characteristics of PSE-like turkey rolls. Turkey Pectoralis major muscles were exposed to either 40 °C to stimulate typical processing causing PSE or 0 °C to reduce PSE and keep the muscles "normal". Turkey rolls were prepared in nine different formulations; using 100% normal (N), 50% normal + 50% PSE (NP) or 100% PSE meat (P). Treatments also included 0, 1 or 2% EA. Addition of EA increased protein content of all samples. L*, a* and b* values were affected by PSE level. Increased levels of PSE caused decreased processing yields, while EA incorporation increased processing yield of the samples. Addition of 1% EA increased water-holding capacity (WHC) of the samples, while higher level of EA (2%) caused decrement in the same. Addition of either 1% or 2% EA was effective in reducing purge loss in P samples. Texture profile analysis showed that EA addition rather had considerable effects on N samples. Sensory scores showed that 1% EA utilization has the potential to increase mostly the mouthfeel of PSE-like products. Results showed that EA could be used as a promising ingredient that improved overall quality of PSE-like turkey rolls.

  19. (Finite) statistical size effects on compressive strength

    PubMed Central

    Weiss, Jérôme; Girard, Lucas; Gimbert, Florent; Amitrano, David; Vandembroucq, Damien

    2014-01-01

    The larger structures are, the lower their mechanical strength. Already discussed by Leonardo da Vinci and Edmé Mariotte several centuries ago, size effects on strength remain of crucial importance in modern engineering for the elaboration of safety regulations in structural design or the extrapolation of laboratory results to geophysical field scales. Under tensile loading, statistical size effects are traditionally modeled with a weakest-link approach. One of its prominent results is a prediction of vanishing strength at large scales that can be quantified in the framework of extreme value statistics. Despite a frequent use outside its range of validity, this approach remains the dominant tool in the field of statistical size effects. Here we focus on compressive failure, which concerns a wide range of geophysical and geotechnical situations. We show on historical and recent experimental data that weakest-link predictions are not obeyed. In particular, the mechanical strength saturates at a nonzero value toward large scales. Accounting explicitly for the elastic interactions between defects during the damage process, we build a formal analogy of compressive failure with the depinning transition of an elastic manifold. This critical transition interpretation naturally entails finite-size scaling laws for the mean strength and its associated variability. Theoretical predictions are in remarkable agreement with measurements reported for various materials such as rocks, ice, coal, or concrete. This formalism, which can also be extended to the flowing instability of granular media under multiaxial compression, has important practical consequences for future design rules. PMID:24733930

  20. Effect of viscosity on rolling-element fatigue life at cryogenic temperature with fluorinated ether lubricants

    NASA Technical Reports Server (NTRS)

    Dietrich, M. W.; Zaretsky, E. V.

    1975-01-01

    Rolling-element fatigue tests were conducted with 12.7-mm-(1/2-in.-) diameter AISI 52100 steel balls in the NASA five-ball fatigue tester, with a maximum hertz stress of 5500 mN/m2 (800 000 psi), a shaft speed of 4750 rpm, lubricant temperature of 200 K (360 R), a contact angle of 20 deg, using four fluorinated ether lubricants of varying viscosities. No statistically significant differences in rolling-element fatigue life occurred using the four viscosity levels. Elastohydrodynamic calculations indicate that values of the lubricant film parameter were approximately 2 or greater.

  1. Epigenetic effects of nano-sized materials.

    PubMed

    Stoccoro, Andrea; Karlsson, Hanna L; Coppedè, Fabio; Migliore, Lucia

    2013-11-08

    The term epigenetics includes several phenomena such as DNA methylation, histone tail modifications, and microRNA mediated mechanisms, which are able to mold the chromatin structure and/or gene expression levels, without altering the primary DNA sequence. Environmental agents can exert epigenetic properties and there is increasing evidence of epigenetic deregulation of gene expression in several human diseases, including cancer, cardiovascular diseases, autism spectrum disorders, autoimmune diseases, and neurodegeneration, among others. Given the widespread use and dispersion in the environment of nano-sized materials, this article summarizes the studies performed so far to evaluate their potential epigenetic properties. Those studies highlight the ability of certain nano-sized compounds to induce an impaired expression of genes involved in DNA methylation reactions leading to global DNA methylation changes, as well as changes of gene specific methylation of tumor suppressor genes, inflammatory genes, and DNA repair genes, all potentially involved in cancer development. Moreover, some nano-sized compounds are able to induce changes in the acetylation and methylation of histone tails, as well as microRNA deregulated expression. We also provided a detailed description of currently available methodologies to evaluate epigenetic modifications. Standard protocols are currently available to evaluate cytotoxic and genotoxic effects of nano-sized materials. By contrast, there are at present no available standard protocols to evaluate the epigenetic potential of any given compound. The currently available methodologies offer different, but often complementary information to characterize potential epigenetic changes induced by exposure to nano-sized compounds. Given the widespread use and dispersion in the environment of nano-sized materials, at present and foreseeable in the near future, and in light of the indication of potential epigenetic properties here reviewed, more

  2. Effect of Microstructure and Texture on Anisotropy and Mechanical Properties of SAE 970X Steel Under Hot Rolling

    NASA Astrophysics Data System (ADS)

    Masoumi, Mohammad; Mohtadi-Bonab, M. A.; de Abreu, Hamilton Ferreira Gomes

    2016-07-01

    This paper presents the effect of microstructure and crystallographic texture by developed in hot rolling and different post-treatments on anisotropic and mechanical properties of SAE 970X steel. The experimental results showed that the hot-rolled sample followed by quenching and consequent tempering at 700 °C led to a significant improvement in anisotropic and mechanical properties. This happened due to the reduction in the number of grains oriented with {001} planes parallel to normal direction. Also, the formation of new strain-free and recrystallized grains associated with {111}//ND and {110}//ND directions improved the mechanical properties. These grains corresponded to the close-packed planes in BCC structure as well.

  3. The effect of tooling design parameters on web-warping in the flexible roll forming of UHSS

    SciTech Connect

    Jiao, Jingsi; Weiss, Matthias; Rolfe, Bernard; Mendiguren, Joseba; Galdos, Lander

    2013-12-16

    To reduce weight and improve passenger safety there is an increased need in the automotive industry to use Ultra High Strength Steels (UHSS) for structural and crash components. However, the application of UHSS is restricted by their limited formability and the difficulty of forming them in conventional processes. An alternative method of manufacturing structural auto body parts from UHSS is the flexible roll forming process which can accommodate materials with high strength and limited ductility in the production of complex and weight-optimised components. However, one major concern in the flexible roll forming is web-warping, which is the height deviation of the profile web area. This paper investigates, using a numerical model, the effect on web-warping with respect to various forming methods. The results demonstrate that different forming methods lead to different amount of web-warping in terms of forming the product with identical geometry.

  4. Effects of macromolecular crowding on nuclear size.

    PubMed

    Rosania, G R; Swanson, J A

    1995-05-01

    The concentration of macromolecules inside cells is high, and the resultant crowding of cytoplasm can be expected to affect many interactions involving macromolecular assemblies. Here, we have examined the effect of solute size and concentration on nuclear volume in saponin-permeabilized macrophages. Nuclei swelled in the presence of small solutes and shrank reversibly in the presence of larger permeant solutes. Remarkably, the smallest solutes capable of shrinking the nucleus were not excluded by the pores in the nuclear envelope. Indeed, nuclei shrank in the presence of such solutes even after the nuclear envelope had been sheared mechanically or permeabilized with detergent. Nuclei extracted with 1% Triton X-100 shrank in the presence of very high concentrations of small solute molecules (30% w/v) as well as in lower concentrations of larger solutes. Consistent with a macromolecular crowding effect, changes in nuclear volume were dependent on solute size and not simply dependent on the colligative properties of solutes or the exclusion of solutes by the nuclear envelope. Solute size-dependent changes in nuclear volume were independent of the chemical nature of the solutes and of the activity of the ions in the buffer. Together, these observations indicate that high concentrations of macromolecules such as those found inside cells can influence the size of the nucleus by directly affecting nuclear structure.

  5. Effect of coil cooling conditions on microstructural and mechanical properties uniformity of flat hot rolled AHSS

    NASA Astrophysics Data System (ADS)

    Kaputkina, L. M.; Marmulev, A. V.; Poliak, E. I.; Herman, G.

    2013-03-01

    Experimental and computational results of measurement of the temperature field due to cooling of coils of hot-rolled strip from low-carbon high-strength steel are presented. It is shown that in a conventional production process the coils cool nonuniformly. The nonuniformity of the cooling causes inhomogeneity of the properties both over the length of the strip and over its width.

  6. Effect of temper rolling on the bake-hardening behavior of low carbon steel

    NASA Astrophysics Data System (ADS)

    Kuang, Chun-fu; Zhang, Shen-gen; Li, Jun; Wang, Jian; Li, Pei

    2015-01-01

    In a typical process, low carbon steel was annealed at two different temperatures (660°C and 750°C), and then was temper rolled to improve the mechanical properties. Pre-straining and baking treatments were subsequently carried out to measure the bake-hardening (BH) values. The influences of annealing temperature and temper rolling on the BH behavior of the steel were investigated. The results indicated that the microstructure evolution during temper rolling was related to carbon atoms and dislocations. After an apparent increase, the BH value of the steel significantly decreased when the temper rolling reduction was increased from 0% to 5%. This was attributed to the increase in solute carbon concentration and dislocation density. The maximum BH values of the steel annealed at 660°C and 750°C were 80 MPa and 89 MPa at the reductions of 3% and 4%, respectively. Moreover, increasing the annealing temperature from 660 to 750°C resulted in an obvious increase in the BH value due to carbide dissolution.

  7. Empirically Based Criteria for Determining Meaningful Effect Size.

    ERIC Educational Resources Information Center

    Barnette, J. Jackson; McLean, James E.

    The purpose of this study was to determine: (1) the extent to which effect sizes vary by chance; (2) the proportion of standardized effect sizes that achieve or exceed commonly used criteria for small, medium, and large effect sizes; (3) whether standardized effect sizes are random or systematic across numbers of groups and sample sizes; and (4)…

  8. Size segregation in the Brazil nut effect

    NASA Astrophysics Data System (ADS)

    Soterroni, Aline C.; Ramos, Fernando M.

    2013-10-01

    Granular materials are ubiquitous in nature and in our daily lives, and used in many industrial processes. Depending on the physical conditions that they are subjected, granular materials may present unusual behavior, combining properties of solids, liquids or gases, and displaying interesting and diversified phenomena. In this work we numerically simulated a granular system in order to investigate the phenomena of size segregation in the Brazil Nut Effect. Our simulations indicate that the phenomenon of size segregation results from the combined effect of two different mechanisms: buoyancy and convection. Increasing the vibration amplitude, the behavior of the system becomes less periodic and more turbulent, with evidence of deterministic chaos in the dynamics of the large particle.

  9. Crash Simulation of Roll Formed Parts by Damage Modelling Taking Into Account Preforming Effects

    NASA Astrophysics Data System (ADS)

    Till, Edwin T.; Hackl, Benjamin; Schauer, Hermann

    2011-08-01

    Complex phase steels of strength levels up to 1200 MPa are suitable to roll forming. These may be applied in automotive structures for enhancing the crashworthiness, e. g. as stiffeners in doors. Even though the strain hardening of the material is low there is considerable bending formability. However ductility decreases with the strength level. Higher strength requires more focus to the structural integrity of the part during the process planning stage and with respect to the crash behavior. Nowadays numerical simulation is used as a process design tool for roll-forming in a production environment. The assessment of the stability of a roll forming process is quite challenging for AHSS grades. There are two objectives of the present work. First to provide a reliable assessment tool to the roll forming analyst for failure prediction. Second to establish simulation procedures in order to predict the part's behavior in crash applications taking into account damage and failure. Today adequate ductile fracture models are available which can be used in forming and crash applications. These continuum models are based on failure strain curves or surfaces which depend on the stress triaxiality (e. g. Crach or GISSMO) and may additionally include the Lode angle (extended Mohr Coulomb or extended GISSMO model). A challenging task is to obtain the respective failure strain curves. In the paper the procedure is described in detail how these failure strain curves are obtained using small scale tests within voestalpine Stahl, notch tensile-, bulge and shear tests. It is shown that capturing the surface strains is not sufficient for obtaining reliable material failure parameters. The simulation tool for roll-forming at the site of voestalpine Krems is Copra® FEA RF, which is a 3D continuum finite element solver based on MSC.Marc. The simulation environment for crash applications is LS-DYNA. Shell elements are used for this type of analyses. A major task is to provide results of

  10. Storage effects on genomic DNA in rolled and mature coca leaves.

    PubMed

    Johnson, Emanuel L; Kim, Soo-Hyung; Emche, Stephen D

    2003-08-01

    Rolled and mature leaf tissue was harvested from Erythroxylum coca var. coca Lam. (coca) to determine a method for storage that would maintain DNA with high quality and content up to 50 days. Harvesting coca leaf tissue under Andean field conditions often requires storage from 3 to 10 days before extraction where tissue integrity is lost. All samples of rolled and mature coca leaf tissue were harvested and separately stored fresh in RNAlater for 50 days at 4 degrees, -20 degrees, and 23 degrees C, while similar samples were air-dried for 72 h at 23 degrees C or oven-dried for 72 h at 40 degrees C after storage, before extraction. Triplicate samples of each tissue type were extracted for DNA at 10-day intervals and showed that DNA integrity and content were preserved in leaf tissue stored at 4 degrees and -20 degrees C for 50 days. Rolled and mature leaf tissue stored at 4 degrees, -20 degrees, and 23 degrees C showed insignificant degradation of DNA after 10 days, and by day 50, only leaf tissue stored at 4 degrees and -20 degrees C had not significantly degraded. All air- and oven-dried leaf tissue extracts showed degradation upon drying (day 0) and continuous degradation up to day 50, despite storage conditions. Amplified fragment length polymorphism analysis of DNA from rolled and mature leaf tissue of coca stored at 4 degrees and -20 degrees C for 0, 10, and 50 days showed that DNA integrity and content were preserved. We recommend that freshly harvested rolled or mature coca leaf tissue be stored at 4 degrees, -20 degrees, and 23 degrees C for 10 days after harvest, and if a longer storage is required, then store at 4 degrees or -20 degrees C.

  11. Stochastic disks that roll.

    PubMed

    Holmes-Cerfon, Miranda

    2016-11-01

    We study a model of rolling particles subject to stochastic fluctuations, which may be relevant in systems of nano- or microscale particles where rolling is an approximation for strong static friction. We consider the simplest possible nontrivial system: a linear polymer of three disks constrained to remain in contact and immersed in an equilibrium heat bath so the internal angle of the polymer changes due to stochastic fluctuations. We compare two cases: one where the disks can slide relative to each other and the other where they are constrained to roll, like gears. Starting from the Langevin equations with arbitrary linear velocity constraints, we use formal homogenization theory to derive the overdamped equations that describe the process in configuration space only. The resulting dynamics have the formal structure of a Brownian motion on a Riemannian or sub-Riemannian manifold, depending on if the velocity constraints are holonomic or nonholonomic. We use this to compute the trimer's equilibrium distribution with and without the rolling constraints. Surprisingly, the two distributions are different. We suggest two possible interpretations of this result: either (i) dry friction (or other dissipative, nonequilibrium forces) changes basic thermodynamic quantities like the free energy of a system, a statement that could be tested experimentally, or (ii) as a lesson in modeling rolling or friction more generally as a velocity constraint when stochastic fluctuations are present. In the latter case, we speculate there could be a "roughness" entropy whose inclusion as an effective force could compensate the constraint and preserve classical Boltzmann statistics. Regardless of the interpretation, our calculation shows the word "rolling" must be used with care when stochastic fluctuations are present.

  12. Stochastic disks that roll

    NASA Astrophysics Data System (ADS)

    Holmes-Cerfon, Miranda

    2016-11-01

    We study a model of rolling particles subject to stochastic fluctuations, which may be relevant in systems of nano- or microscale particles where rolling is an approximation for strong static friction. We consider the simplest possible nontrivial system: a linear polymer of three disks constrained to remain in contact and immersed in an equilibrium heat bath so the internal angle of the polymer changes due to stochastic fluctuations. We compare two cases: one where the disks can slide relative to each other and the other where they are constrained to roll, like gears. Starting from the Langevin equations with arbitrary linear velocity constraints, we use formal homogenization theory to derive the overdamped equations that describe the process in configuration space only. The resulting dynamics have the formal structure of a Brownian motion on a Riemannian or sub-Riemannian manifold, depending on if the velocity constraints are holonomic or nonholonomic. We use this to compute the trimer's equilibrium distribution with and without the rolling constraints. Surprisingly, the two distributions are different. We suggest two possible interpretations of this result: either (i) dry friction (or other dissipative, nonequilibrium forces) changes basic thermodynamic quantities like the free energy of a system, a statement that could be tested experimentally, or (ii) as a lesson in modeling rolling or friction more generally as a velocity constraint when stochastic fluctuations are present. In the latter case, we speculate there could be a "roughness" entropy whose inclusion as an effective force could compensate the constraint and preserve classical Boltzmann statistics. Regardless of the interpretation, our calculation shows the word "rolling" must be used with care when stochastic fluctuations are present.

  13. Effects of ground, steam-flaked, and steam-rolled corn grains on performance of lactating cows.

    PubMed

    Yu, P; Huber, J T; Santos, F A; Simas, J M; Theurer, C B

    1998-03-01

    Five types of processed corn were compared to determine the effects of processing on lactational performance and nutrient digestibilities in dairy cows. Forty lactating Holstein cows averaging 160 +/- 60 d in milk were randomly divided into five groups on the basis of pretreatment milk yields and were fed diets containing 40% corn grain for 56 d. Treatments were 1) finely ground corn, 2) coarsely ground corn, 3) steam-flaked corn at a low density, 4) steam-flaked corn at a medium density, and 5) steam-rolled corn. Cows fed the diet containing steam-flaked corn at a medium density had a higher milk yield (37.1 kg/d) than did cows fed the diets containing coarsely ground corn, steam-flaked corn at a low density, or steam-rolled corn; cows fed the diet containing finely ground corn had an intermediate milk yield (35.5 kg/d). Efficiency of feed utilization was greater, and dry matter intake was lower, for cows fed the diet containing finely ground corn than for cows fed the other diets. The fat content of milk was higher for cows fed the diets containing coarsely ground corn and steam-rolled corn than for cows fed the diet containing steam-flaked corn at a medium density. Milk protein and SNF contents and yields of protein, lactose, and SNF did not differ among diets. Apparent starch digestibilities in the total digestive tract were lower for diets containing coarsely ground corn (87.4%) and steam-rolled corn (91.3%) than for the other diets (X = 96.3%). Milk yield was highest for cows fed the diet containing steam-flaked corn with a medium density. Fine grinding resulted in the greatest efficiency of feed utilization.

  14. CONTROL FOR ROLLING MILL

    DOEpatents

    Shuck, A.B.; Shaw, W.C.

    1961-06-20

    A plutonium-rolling apparatus is patented that has two sets of feed rolls, shaping rolls between the feed rolls, and grippers beyond the feed rolls, which ready a workpiece for a new pass through the shaping rolls by angularly shifting the workpiece about its axis or transversely moving it on a line parallel to the axes of the shaping rolls. Actuation of each gripper for gripping or releasing the workpiece is produced by the relative positions assumed by the feed rolls adjacent to the gripper as the workpiece enters or leaves the feed rolls.

  15. Estimation of stiffening effect of shaft and housing material outside projected area of a rolling element bearing

    NASA Technical Reports Server (NTRS)

    Taylor, C. M.

    1977-01-01

    In the analysis of distortions occurring in rolling-element bearings, it is common to neglect the stiffening effect of shafting outside the bearing region. The magnitude of such an effect will be dependent primarily on the bearing width-to-bore ratio, the shaft geometry, and the location of the bearing on the shaft. An estimate is given of the stiffening effect for a wide range of these variables. In addition, brief consideration is given to the parallel situation existing at the outer ring housing.

  16. The Relationship between Sample Sizes and Effect Sizes in Systematic Reviews in Education

    ERIC Educational Resources Information Center

    Slavin, Robert; Smith, Dewi

    2009-01-01

    Research in fields other than education has found that studies with small sample sizes tend to have larger effect sizes than those with large samples. This article examines the relationship between sample size and effect size in education. It analyzes data from 185 studies of elementary and secondary mathematics programs that met the standards of…

  17. The Relationship between Sample Sizes and Effect Sizes in Systematic Reviews in Education

    ERIC Educational Resources Information Center

    Slavin, Robert; Smith, Dewi

    2009-01-01

    Research in fields other than education has found that studies with small sample sizes tend to have larger effect sizes than those with large samples. This article examines the relationship between sample size and effect size in education. It analyzes data from 185 studies of elementary and secondary mathematics programs that met the standards of…

  18. Effect of Thermal Cycling on Creep Behavior of Powder-Metallurgy-Processed and Hot-Rolled Al and Al-SiC Particulate Composites

    NASA Astrophysics Data System (ADS)

    Pal, Sharmilee; Bhanuprasad, V. V.; Mitra, R.; Ray, K. K.

    2009-12-01

    The tensile creep behavior of powder metallurgy (P/M)-processed and hot-rolled commercially pure Al and Al-5 or Al-10 vol pct SiC particulate composites has been evaluated after subjecting to 0, 2, and 8 thermal cycles between 500 °C and 0 °C with rapid quenching. The images of microstructures obtained using scanning and transmission electron microscopy as well as changes in the electrical resistivity, Young’s modulus, and microhardness have been examined in the samples subjected to thermal cycling, in order to compare the effects of structural damage and strengthening by dislocation generation. The damage is caused by voids formed by vacancy coalescence, and is more severe in pure Al than in Al-SiCp composites, because the particle-matrix interfaces in the composites act as effective sinks for vacancies. Creep tests have shown that the application of 2 thermal cycles lowers the creep strain rates in both pure Al and Al-SiCp composites. However, the creep resistance of pure Al gets significantly deteriorated, unlike the mild deterioration in the Al-5 SiCp composite, while the time to rupture for the Al-10 SiCp composite is increased. The dislocation structure and subgrain sizes in the Al and in the matrices of the Al-SiCp composites in the as-rolled condition, after thermal cycling, and after creep tests, have been compared and related to the creep behavior. The dimple sizes of the crept fracture surfaces appear to be dependent on the void density, tertiary component of strain, and time to rupture.

  19. Rolling Uphill

    NASA Astrophysics Data System (ADS)

    Cross, Rod

    2017-04-01

    In a recent letter to this journal, Mungan noted that translational energy can be converted into gravitational potential energy when an object is projected vertically, but rotational energy is not usually converted in this manner. As an exception, he gave an example where "a ball initially rolling without slipping will travel higher up a rough ramp than it will up a frictionless ramp." However, such a result is unlikely to be observed in practice. A better example would be a ball spinning rapidly forwards as it slides up the ramp, since the friction force on the ball then acts in a direction up the ramp.

  20. Roll mill for milling coal

    SciTech Connect

    Brundiek, H.; Werner, L.

    1984-02-21

    A roll mill, more specially for coal, has a turning pan and a number of rolls running thereon for producing a milling effect. Each roll is supported on a rocker arm, able to be turned about a horizontal axis which is roughly tangential to the pan. The rocker arm and the roll on it are forced down against the pan by a hydraulic cylinder joined with a fork which, in turn, is joined with the rocker arm for turning it about the turnpin. The fork may be unjoined from the rocker arm for upkeep work on the roll. Each rocker arm has a gas-tight cover structure which is part of the casing of the mill.

  1. Improved strength and ductility of high alloy containing Al-12Zn-3Mg-2.5Cu alloy by combining non-isothermal step rolling and cold rolling

    NASA Astrophysics Data System (ADS)

    Ravikumar, V. V.; Kumaran, S.

    2017-02-01

    Al-12Zn-3Mg-2.5Cu alloy was prepared using a liquid metallurgy route under the optimized conditions. A sample cut from the ingot was rolled non-isothermally from 400°C to 100°C in 100°C steps, with 15% reduction in thickness; it was then cold rolled isothermally at room temperature for 85% reduction. The cold-rolled alloys were characterized by electron microscopy, hardness test, and tensile test to elucidate their structural evolution and evaluate their mechanical behavior. In the results, the cast alloy consists of α-aluminum and various intermetallic compounds. These compounds are segregated along the grain boundaries, which makes the alloy difficult to roll at room temperature. The combined effect of non-isothermal step rolling and cold rolling results in the nano/microsized compounds distributed uniformly in the matrix. The hardness is substantially increased after rolling. This increase in hardness is attributed to the ultra-fine grain size, fine-scale intermetallic compounds, and structural defects (e.g., dislocations, stacking faults, and sub-grains). The ultimate tensile strength of the rolled alloy is approximately 628 MPa with 7% ductility.

  2. Roll Casting of Al-25%Si

    SciTech Connect

    Haga, Toshio; Harada, Hideto; Watari, Hisaki

    2011-05-04

    Strip casting of Al-25%Si strip was tried using an unequal diameter twin roll caster. The diameter of the lower roll (large roll) was 1000 mm and the diameter of the upper roll (small roll) was 250 mm. Roll material was mild steel. The sound strip could be cast at the speeds ranging from 8 m/min to 12 m/min. The strip did not stick to the roll without the parting material. The primary Si, which existed at centre area of the thickness direction, was larger than that which existed at other area. The size of the primary Si was smaller than 0.2 mm. Eutectic Si was smaller 5 {mu}m. The as-cast strip was ranging from 2 mm to 3 mm thick and its width was 100 mm. The as-cast strip could be hot rolled down to 1 mm. The hot rolled strip was cold rolled. The primary Si became smaller and the pore occurred around the primary Si after the rolling.

  3. Decoding mobile-phone image sensor rolling shutter effect for visible light communications

    NASA Astrophysics Data System (ADS)

    Liu, Yang

    2016-01-01

    Optical wireless communication (OWC) using visible lights, also known as visible light communication (VLC), has attracted significant attention recently. As the traditional OWC and VLC receivers (Rxs) are based on PIN photo-diode or avalanche photo-diode, deploying the complementary metal-oxide-semiconductor (CMOS) image sensor as the VLC Rx is attractive since nowadays nearly every person has a smart phone with embedded CMOS image sensor. However, deploying the CMOS image sensor as the VLC Rx is challenging. In this work, we propose and demonstrate two simple contrast ratio (CR) enhancement schemes to improve the contrast of the rolling shutter pattern. Then we describe their processing algorithms one by one. The experimental results show that both the proposed CR enhancement schemes can significantly mitigate the high-intensity fluctuations of the rolling shutter pattern and improve the bit-error-rate performance.

  4. Hot rolled asphalt: Effect of binder properties on resistance to deformation

    NASA Astrophysics Data System (ADS)

    Jacobs, F. A.

    Those properties of binders that most affect the resistance to deformation of rolled asphalt are discussed. Thirteen binders were studied and mixtures containing them were subjected to design tests and the wheel tracking test. These laboratory mechanical tests show that, within the range of binders tested, significant improvements in resistance to deformation can be achieved over a range of high road temperatures by increasing the softening point of the binder, irrespective of its penetration at 25 C.

  5. The Role of Thermoelastic Effects in the Scuffing Failure of Rolling/Sliding EHD Contacts

    DTIC Science & Technology

    1988-08-15

    Avsi i)!or TABLE OF CONTENTS FACE ABSTRACT INTRODUCTION ........... ............................ I SUMMARY AND FUTURE WORK... Table 1. Figure 3a indicates that the peak surface temperature for pure rolling occurs in the inlet zone near the point of maximum pressure gradient...CO Iq r4,) N~ 0 0 0 d 0 0 o 0 Q 0 14 Table 1. Disk and lubriant properties Material of both disks steel Lubricart, synthetic paraffinic hydrocarbon

  6. Size effects in lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Hu-Rong, Yao; Ya-Xia, Yin; Yu-Gao, Guo

    2016-01-01

    Size-related properties of novel lithium battery materials, arising from kinetics, thermodynamics, and newly discovered lithium storage mechanisms, are reviewed. Complementary experimental and computational investigations of the use of the size effects to modify electrodes and electrolytes for lithium ion batteries are enumerated and discussed together. Size differences in the materials in lithium ion batteries lead to a variety of exciting phenomena. Smaller-particle materials with highly connective interfaces and reduced diffusion paths exhibit higher rate performance than the corresponding bulk materials. The thermodynamics is also changed by the higher surface energy of smaller particles, affecting, for example, secondary surface reactions, lattice parameter, voltage, and the phase transformation mechanism. Newly discovered lithium storage mechanisms that result in superior storage capacity are also briefly highlighted. Project supported by the National Natural Science Foundation of China (Grant Nos. 51225204 and 21303222), the Shandong Taishan Scholarship, China, the Ministry of Science and Technology, China (Grant No. 2012CB932900), and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA09010000).

  7. Effect of hot rolling on the structure and the mechanical properties of nitrogen-bearing austenitic-martensitic 14Kh15AN4M steel

    NASA Astrophysics Data System (ADS)

    Bannykh, O. A.; Betsofen, S. Ya.; Lukin, E. I.; Blinov, V. M.; Voznesenskaya, N. M.; Tonysheva, O. A.; Blinov, E. V.

    2016-04-01

    The effect of the rolling temperature and strain on the structure and the properties of corrosionresistant austenitic-martensitic 14Kh15AN4M steel is studied. The steel is shown to exhibit high ductility: upon rolling in the temperature range 700-1100°C at a reduction per pass up to 80%, wedge steel specimens are uniformly deformed along and across the rolling direction without cracking and other surface defects. Subsequent cold treatment and low-temperature tempering ensure a high hardness of the steel (50-56 HRC). Austenite mainly contributes to the hardening upon rolling in the temperature range 700-800°C at a reduction of 50-70%, and martensite makes the main contribution at higher temperatures and lower strains. Texture does not form under the chosen deformation conditions, which indicates dynamic recrystallization with the nucleation and growth of grains having no preferential orientation.

  8. Planarization process of single crystalline silicon asperity under abrasive rolling effect studied by molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Si, Lina; Guo, Dan; Luo, Jianbin; Xie, Guoxin

    2012-10-01

    In the chemical mechanical polishing (CMP) process, the complex behaviors of abrasive particles play important roles in the planarization of wafer surface. Particles embedded in the pad remove materials by ploughing, while particles immersed in the slurry by rolling across the wafer surface. In this paper, processes of the particle rolling across a silicon surface with an asperity under various down forces and external driving forces were studied using molecular dynamics (MD) simulation method. The simulations clarified the asperity shape evolution during the rolling process and analyzed the energy changes of the simulation system and the interaction forces acted on the silica particle. It was shown that both the down force and the driving force had important influences on the amount of the material removed. With relatively small down forces and driving forces applied on the particle, the material removal occurred mainly in the front end of the asperity; when the down forces and driving forces were large enough, e.g., 100 nN, the material removal could take place at the whole top part of the asperity. The analysis of energy changes and interaction forces provided favorable explanations to the simulation results.

  9. Analysis of Effects of Interceptor Roll Performance and Maneuverability on Success of Collision-Course Attack

    NASA Technical Reports Server (NTRS)

    Phillips, William H.

    1961-01-01

    An attempt has been made to determine the importance of rolling performance and other factors in the design of an interceptor which uses collision-course tactics. A graphical method is presented for simple visualization of attack situations. By means of diagrams showing vectoring limits, that is, the ranges of interceptor position and heading from which attacks may be successfully completed, the relative importance of rolling performance and normal-acceleration capability in determining the success of attacks is illustrated. The results indicate that the reduction in success of attacks due to reduced rolling performance (within the limits generally acceptable from the pilots' standpoint) is very small, whereas the benefits due to substantially increasing the normal-acceleration capability are large. Additional brief analyses show that the optimum speed for initiating a head-on attack is often that corresponding to the upper left-hand corner of the V-g diagram. In these cases, increasing speed beyond this point for given values of normal acceleration and radar range rapidly decreases the width of the region from which successful attacks can be initiated. On the other hand, if the radar range is increased with a variation somewhere between the first and second power of the interceptor speed, the linear dimensions of the region from which successful attacks can be initiated vary as the square of the interceptor speed.

  10. Effect of Silicon Nitride Balls and Rollers on Rolling Bearing Life

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.; Vlcek, Brian L.; Hendricks, Robert C.

    2005-01-01

    Three decades have passed since the introduction of silicon nitride rollers and balls into conventional rolling-element bearings. For a given applied load, the contact (Hertz) stress in a hybrid bearing will be higher than an all-steel rolling-element bearing. The silicon nitride rolling-element life as well as the lives of the steel races were used to determine the resultant bearing life of both hybrid and all-steel bearings. Life factors were determined and reported for hybrid bearings. Under nominal operating speeds, the resultant calculated lives of the deep-groove, angular-contact, and cylindrical roller hybrid bearings with races made of post-1960 bearing steel increased by factors of 3.7, 3.2, and 5.5, respectively, from those calculated using the Lundberg-Palmgren equations. An all-steel bearing under the same load will have a longer life than the equivalent hybrid bearing under the same conditions. Under these conditions, hybrid bearings are predicted to have a lower fatigue life than all-steel bearings by 58 percent for deep-groove bearings, 41 percent for angular-contact bearings, and 28 percent for cylindrical roller bearings.

  11. Effect of starvation on film thickness and traction under elastohydrodynamic rolling and sliding conditions

    NASA Technical Reports Server (NTRS)

    Wedeven, L. D.

    1975-01-01

    Traction measurements under starved elastohydrodynamic conditions were obtained for a point-contact geometry. Simultaneous measurements of the film thickness and the location of the inlet lubricant boundary were made. Optical interferometry was used to measure film thickness. The thickness of a starved film for combined rolling and sliding conditions varies with the location of the inlet boundary in the same way as previously found for pure rolling conditions. When the fluid velocity distribution is calculated in the inlet region by a Reynolds lubrication analysis, backflow is seen to occur over a portion of the inlet region. Backflow is essential for the establishment of a flooded condition. The location of certain fluid velocity conditions within the inlet region, as suggested in the literature, does not adequately describe the onset of starvation. For the same slide-roll ratio a starved film was observed to possess greater traction than a flooded film. Traction measurements under starved conditions were also compared with those under flooded conditions for equivalent shear rates in the Hertzian region. When the shear rates within the Hertzian region were low and the film was severely starved, the measured tractions were lower than expected. This may be due to large shear stresses developed by the large pressure gradients that are generated in the inlet region when it is severely starved.

  12. The effect of external dynamic loads on the lifetime of rolling element bearings: accurate measurement of the bearing behaviour

    NASA Astrophysics Data System (ADS)

    Jacobs, W.; Boonen, R.; Sas, P.; Moens, D.

    2012-05-01

    Accurate prediction of the lifetime of rolling element bearings is a crucial step towards a reliable design of many rotating machines. Recent research emphasizes an important influence of external dynamic loads on the lifetime of bearings. However, most lifetime calculations of bearings are based on the classical ISO 281 standard, neglecting this influence. For bearings subjected to highly varying loads, this leads to inaccurate estimations of the lifetime, and therefore excessive safety factors during the design and unexpected failures during operation. This paper presents a novel test rig, developed to analyse the behaviour of rolling element bearings subjected to highly varying loads. Since bearings are very precise machine components, their motion can only be measured in an accurately controlled environment. Otherwise, noise from other components and external influences such as temperature variations will dominate the measurements. The test rig is optimised to perform accurate measurements of the bearing behaviour. Also, the test bearing is fitted in a modular structure, which guarantees precise mounting and allows testing different types and sizes of bearings. Finally, a fully controlled multi-axial static and dynamic load is imposed on the bearing, while its behaviour is monitored with capacitive proximity probes.

  13. Optimal Context Size in Elementary Schools: Disentangling the Effects of Class Size and School Size

    ERIC Educational Resources Information Center

    Ready, Douglas D.; Lee, Valerie E.

    2007-01-01

    Young children's learning--and how their learning is distributed by social background--may be influenced by the structural and organizational properties of their school. This study focuses on one important structural dimension of these educational contexts: "size." This study differs from extant studies linking size to student outcomes in four…

  14. Size effects on miniature Stirling cycle cryocoolers

    NASA Astrophysics Data System (ADS)

    Yang, Xiaoqin; Chung, J. N.

    2005-08-01

    Size effects on the performance of Stirling cycle cryocoolers were investigated by examining each individual loss associated with the regenerator and combining these effects. For the fixed cycle parameters and given regenerator length scale, it was found that only for a specific range of the hydrodynamic diameter the system can produce net refrigeration and there is an optimum hydraulic diameter at which the maximum net refrigeration is achieved. When the hydraulic diameter is less than the optimum value, the regenerator performance is controlled by the pressure drop loss; when the hydraulic diameter is greater than the optimum value, the system performance is controlled by the thermal losses. It was also found that there exists an optimum ratio between the hydraulic diameter and the length of the regenerator that offers the maximum net refrigeration. As the regenerator length is decreased, the optimum hydraulic diameter-to-length ratio increases; and the system performance is increased that is controlled by the pressure drop loss and heat conduction loss. Choosing appropriate regenerator characteristic sizes in small-scale systems are more critical than in large-scale ones.

  15. Size effects in thermal conduction by phonons

    NASA Astrophysics Data System (ADS)

    Allen, Philip B.

    2014-08-01

    Heat transport in nanoscale systems is both hard to measure microscopically, and hard to interpret. Ballistic and diffusive heat flow coexist, adding confusion. This paper looks at a very simple case: a nanoscale crystal repeated periodically. This is a popular model for simulation of bulk heat transport using classical molecular dynamics (MD), and is related to transient thermal grating experiments. Nanoscale effects are seen in perhaps their simplest form. The model is solved by an extension of standard quasiparticle gas theory of bulk solids. Both structure and heat flow are constrained by periodic boundary conditions. Diffusive transport is fully included, while ballistic transport by phonons of a long mean free path is diminished in a specific way. Heat current J (x) and temperature gradient ∇T (x') have a nonlocal relationship, via κ (x-x'), over a distance |x-x'| determined by phonon mean free paths. In MD modeling of bulk conductivity, finite computer resources limit system size. Long mean free paths, comparable to the scale of heating and cooling, cause undesired finite-size effects that have to be removed by extrapolation. The present model allows this extrapolation to be quantified. Calculations based on the Peierls-Boltzmann equation, using a generalized Debye model, show that extrapolation involves fractional powers of 1/L. It is also argued that heating and cooling should be distributed sinusoidally [ė∝cos(2πx/L)] to improve convergence of numerics.

  16. Effect of sulfur on rolling contact fatigue life of high-manganese precipitation-hardening austenitic steel

    SciTech Connect

    Haruna, Y.; Yamamoto, A.; Tsubakino, H.

    1998-10-05

    For mechanical components used in high magnetic flux such as bearings and shafts that undergo cyclic stress, materials require low permeability with high strength, hardness, appropriate machinability, and good fatigue properties. Although it is implied that low permeability and machinability will be achieved by a selection of sulfurized austenitic ({gamma}) steel grades, effect of manganese sulfide (MnS) on fatigue properties of such grades especially for bearing applications is not clarified. For high-carbon chromium bearing steels, the effect of MnS on rolling contact fatigue life of the steels containing sulfur less than 0.03% are discussed. In these studies, the effect of MnS is not clearly determined whether it is beneficial or harmful to contact fatigue lives of the steels. However, effect of MnS under higher sulfur content, i.e., 0.10%, on the fatigue properties of {gamma} steel has not been studied. In this paper, the effect of sulfur on rolling contact fatigue properties of vanadium added {gamma} steel, 10Cr-6Ni-8Mn-1.6V-0.6C, was investigated focusing on microstructural change in connection with MnS particles.

  17. Information Conversion, Effective Samples, and Parameter Size

    PubMed Central

    Lin, Xiaodong; Pittman, Jennifer; Clarke, Bertrand

    2008-01-01

    Consider the relative entropy between a posterior density for a parameter given a sample and a second posterior density for the same parameter, based on a different model and a different data set. Then the relative entropy can be minimized over the second sample to get a virtual sample that would make the second posterior as close as possible to the first in an informational sense. If the first posterior is based on a dependent dataset and the second posterior uses an independence model, the effective inferential power of the dependent sample is transferred into the independent sample by the optimization. Examples of this optimization are presented for models with nuisance parameters, finite mixture models, and models for correlated data. Our approach is also used to choose the effective parameter size in a Bayesian hierarchical model. PMID:19079764

  18. Frontal Impact of Rolling Spheres.

    ERIC Educational Resources Information Center

    Domenech, A.; Casasus, E.

    1991-01-01

    A model of the inelastic collision between two spheres rolling along a horizontal track is presented, taking into account the effects of frictional forces at impact. This experiment makes possible direct estimates of the coefficients of restitution and friction. (Author)

  19. Effect of the cold-rolling parameters and the yield strength of the strip material on the friction stresses in a deformation zone

    NASA Astrophysics Data System (ADS)

    Garber, E. A.; Yagudin, I. V.; Ermilov, V. V.; Traino, A. I.

    2009-10-01

    The reliability of the methods of determining the friction coefficient is analyzed, since the friction stresses in the deformation zone during cold rolling significantly affect the quality of cold-rolled sheets and the energy consumption. The well-known experimental data and empirical dependences are shown to contradict each other, and the statistical assurance of these dependences is absent. A database on the interrelated technological and energy-force parameters of a five-stand cold-rolling mill, which includes a wide range of steel grades and strip sizes and shapes, is analyzed. Regression analysis is used to obtain a statistically reliable regression dependence of the friction coefficient in the deformation zone on the most significant technological parameters. The application of this dependence decreases the error of energy-force calculations by more than two times.

  20. Publication Bias in Psychology: A Diagnosis Based on the Correlation between Effect Size and Sample Size

    PubMed Central

    Kühberger, Anton; Fritz, Astrid; Scherndl, Thomas

    2014-01-01

    Background The p value obtained from a significance test provides no information about the magnitude or importance of the underlying phenomenon. Therefore, additional reporting of effect size is often recommended. Effect sizes are theoretically independent from sample size. Yet this may not hold true empirically: non-independence could indicate publication bias. Methods We investigate whether effect size is independent from sample size in psychological research. We randomly sampled 1,000 psychological articles from all areas of psychological research. We extracted p values, effect sizes, and sample sizes of all empirical papers, and calculated the correlation between effect size and sample size, and investigated the distribution of p values. Results We found a negative correlation of r = −.45 [95% CI: −.53; −.35] between effect size and sample size. In addition, we found an inordinately high number of p values just passing the boundary of significance. Additional data showed that neither implicit nor explicit power analysis could account for this pattern of findings. Conclusion The negative correlation between effect size and samples size, and the biased distribution of p values indicate pervasive publication bias in the entire field of psychology. PMID:25192357

  1. Publication bias in psychology: a diagnosis based on the correlation between effect size and sample size.

    PubMed

    Kühberger, Anton; Fritz, Astrid; Scherndl, Thomas

    2014-01-01

    The p value obtained from a significance test provides no information about the magnitude or importance of the underlying phenomenon. Therefore, additional reporting of effect size is often recommended. Effect sizes are theoretically independent from sample size. Yet this may not hold true empirically: non-independence could indicate publication bias. We investigate whether effect size is independent from sample size in psychological research. We randomly sampled 1,000 psychological articles from all areas of psychological research. We extracted p values, effect sizes, and sample sizes of all empirical papers, and calculated the correlation between effect size and sample size, and investigated the distribution of p values. We found a negative correlation of r = -.45 [95% CI: -.53; -.35] between effect size and sample size. In addition, we found an inordinately high number of p values just passing the boundary of significance. Additional data showed that neither implicit nor explicit power analysis could account for this pattern of findings. The negative correlation between effect size and samples size, and the biased distribution of p values indicate pervasive publication bias in the entire field of psychology.

  2. Acute Effects of Deep Tissue Foam Rolling and Dynamic Stretching on Muscular Strength, Power, and Flexibility in Division I Linemen.

    PubMed

    Behara, Brandon; Jacobson, Bert H

    2017-04-01

    Behara, B and Jacobson, BH. Acute effects of deep tissue foam rolling and dynamic stretching on muscular strength, power, and flexibility in Division I linemen. J Strength Cond Res 31(4): 888-892, 2017-A recent strategy to increase sports performance is a self-massage technique called myofascial release using foam rollers. Myofascial restrictions are believed to be brought on by injuries, muscle imbalances, overrecruitment, and/or inflammation, all of which can decrease sports performance. The purpose of this study was to compare the acute effects of a single-bout of lower extremity self-myofascial release using a custom deep tissue roller (DTR) and a dynamic stretch protocol. Subjects consisted of NCAA Division 1 offensive linemen (n = 14) at a Midwestern university. All players were briefed on the objectives of the study and subsequently signed an approved IRB consent document. A randomized crossover design was used to assess each dependent variable (vertical jump [VJ] power and velocity, knee isometric torque, and hip range of motion was assessed before and after: [a] no treatment, [b] deep tissue foam rolling, and [c] dynamic stretching). Results of repeated-measures analysis of variance yielded no pretest to posttest significant differences (p > 0.05) among the groups for VJ peak power (p = 0.45), VJ average power (p = 0.16), VJ peak velocity (p = 0.25), VJ average velocity (p = 0.23), peak knee extension torque (p = 0.63), average knee extension torque (p = 0.11), peak knee flexion torque (p = 0.63), or average knee flexion torque (p = 0.22). However, hip flexibility was statistically significant when tested after both dynamic stretching and foam rolling (p = 0.0001). Although no changes in strength or power was evident, increased flexibility after DTR may be used interchangeably with traditional stretching exercises.

  3. Alpha values as a function of sample size, effect size, and power: accuracy over inference.

    PubMed

    Bradley, M T; Brand, A

    2013-06-01

    Tables of alpha values as a function of sample size, effect size, and desired power were presented. The tables indicated expected alphas for small, medium, and large effect sizes given a variety of sample sizes. It was evident that sample sizes for most psychological studies are adequate for large effect sizes defined at .8. The typical alpha level of .05 and desired power of 90% can be achieved with 70 participants in two groups. It was perhaps doubtful if these ideal levels of alpha and power have generally been achieved for medium effect sizes in actual research, since 170 participants would be required. Small effect sizes have rarely been tested with an adequate number of participants or power. Implications were discussed.

  4. Size Effects in Nanoscale Structural Phenomena

    NASA Astrophysics Data System (ADS)

    McElhinny, Kyle Matthew

    The creation of nanostructures offers the opportunity to modify and tune properties in ways inaccessible in bulk materials. A key component in this development is the introduction of size effects which reduce the physical size, dimensionality, and increase the contribution of surface effects. The size effects strongly modify the structural dynamics in nanoscale systems and leads to changes in the vibrational, electrical, and optical properties. An increased level of understanding and control of nanoscale structural dynamics will enable more precise control over nanomaterial transport properties. My work has shown that 1D spatial confinement through the creation of semiconducting nanomembranes modifies the phonon population and dispersion. X ray thermal diffuse scattering distributions show an excess in intensity for nanomembranes less than 100 nm in thickness, for phonon modes with wavevectors spanning the entire Brillouin zone. This excess intensity indicates the development of new low energy phonon modes or the softening of elastic constants. Furthermore, an additional anisotropy in the phonon dispersion is observed with a symmetry matching the direction of spatial confinement. This work has also extended x ray thermal diffuse scattering for use in studying nanomaterials. In electro- and photoactive monolayers a structural reconfiguration can be produced by external optical stimuli. I have developed an electro and photoactive molecular monolayers on oxide surfaces. Using x ray reflectivity, I have evaluated the organization and reconfiguration of molecular monolayers deposited by Langmuir Blodgett technique. I have designed and probed the reconfiguration of optically reconfigurable monolayers of azobenzene donor molecules on semiconducting surfaces. These monolayers reconfigure through a cooperative switching process leading to the development of large isomeric domains. This work represents an advancement in the interpretation of x ray reflectivity from molecular

  5. Rolling magnets down a conductive hill: Revisiting a classic demonstration of the effects of eddy currents

    NASA Astrophysics Data System (ADS)

    Tomasel, Fernando G.; Marconi, Mario C.

    2012-09-01

    We re-examine the case of rare-earth magnets rolling down an inclined plane, presenting an approach to conducting quantitative investigations that results in high-quality experimental data connecting simple experiments to a handful of important applications of eddy currents. These include not only magnetic braking but also the characterization of conductive materials, measurement of the thickness of dielectric coatings, and nondestructive evaluation of conductive objects. The simplicity of the proposed experimental setups, which include the use of widely available smart phones to record video that can be post-processed with free software, makes these experiments appealing to high school and college physics students.

  6. [Effect of rolling compression loading bioreactor on chondrogenesis of rabbit bone marrow mesenchymal stem cells with different loading parameters].

    PubMed

    Sun, Minglin; Zhu, Lei; Lü, Dan; Zhang, Chunqiu

    2013-01-01

    To explore the effect of rolling compression loading bioreactor on chondrogenesis of rabbit bone marrow mesenchymal stem cells (BMSCs) with different loading parameters. BMSCs were isolated from New Zealand rabbits, aged 2.5 months. BMSCs at passage 3 were used to prepare BMSCs-agarose gels (4 mm in diameter and height, respectively). Samples were divided into 8 groups: 10% (group A1), 20% (group A2), and 30% (group A3) compression groups (0.4 Hz, 3 h/d) and 20 minutes (group B1), 3 hours (group B2), and 12 hours (group B3) rolling time groups and static culture (control groups). The living cell rate, the collagen type II and Aggrecan gene expressions, and glycosaminoglycan (GAG) content were determined, and histological staining was done at 24 hours, 7 days, 14 days, and 21 days after culture. At 14 and 21 days, the living cell rates of groups A1 and A2 were significantly higher than that of group A3 (P < 0.05), groups B1 and B2 were significantly higher than group B3 (P < 0.05). Collagen type II and Aggrecan gene expressions of the experimental groups at each time point were significantly higher than those of the control groups (P < 0.05); at 14 and 21 days, collagen type II and Aggrecan gene expressions of groups A1 and A2 were significantly higher than those of group A3, and groups B1 and B2 were also significantly higher than group B3 (P < 0.05). At 14 and 21 days, the GAG contents of groups A1 and A2 were significantly higher than those of group A3 (P < 0.05); groups B1 and B2 were also significantly higher than group B3 (P < 0.05). At 21 days, toluidine blue staining showed that obvious blue-staining and even cartilage lacunae were seen in groups A2 and B2, but light and quite rare blue-staining in groups A1, A3, B1, and B3. The rolling compression loading bioreactor has great promotion effect on chondrogenesis of rabbit BMSCs with rolling parameters of 0.4 Hz, 3 hours, and 20% compression.

  7. Central charges without finite-size effects

    NASA Astrophysics Data System (ADS)

    Fendley, Paul; Intriligator, Ken

    1993-12-01

    We show how to obtain the ultraviolet central charge from the exact S-matrix for a wide variety of models with a U(1) symmetry. This is done by coupling the U(1) current J to a background field. In an N=2 superconformal theory with J the fermion number current, the OPE of J with itself and hence the free energy are proportional to c. By deforming the supersymmetry into affine ? quantum-group symmetry, this result can be generalized to many U(1)-invariant theories, including the N=0 and N=1 sine-Gordon models and the SU(2) kWZW models. This provides a consistency check on a conjectured S-matrix completely independent of the finite-size effects expressed in terms of dilogarithms resulting from the thermodynamic Bethe ansatz.

  8. Microstructure and helium irradiation performance of high purity tungsten processed by cold rolling

    NASA Astrophysics Data System (ADS)

    Chen, Zhe; Han, Wenjia; Yu, Jiangang; Kecskes, Laszlo; Zhu, Kaigui; Wei, Qiuming

    2016-10-01

    This work aims to investigate the effects of confined cold rolling on the evolution of microstructure, hardness, and helium irradiation performance of high purity tungsten (W). Using a final rolling temperature of 450 °C, W samples were severely deformed by confined cold rolling up to equivalent strains (εeq) of 1.6 and 3.3. Experimental results indicate that the average grain size of W specimens processed by confined cold rolling has been greatly reduced, and the rolled W samples with εeq ∼3.3 do not show an "ideal texture" of (001)[110] which is the expected texture of bcc metals processed by conventional cold rolling. The irradiation resistance against 60 keV He+ ions with up to a dose of 1.5 × 1022 ions·m-2 of the rolled W is compared to that of the as-received W. Results show that, due to an improvement of the metal's ductility, blister bursting with a partially opened lid forms on the surface of the rolled W, whereas blister bursting with a fully opened lid forms on the surface of the as-received W.

  9. Microstructural and Material Quality Effects on Rolling Contact Fatigue of Highly Elastic Intermetallic Ball Bearings

    NASA Technical Reports Server (NTRS)

    DellaCorte, Christopher; Howard, S. Adam; Thomas, Fransua; Stanford, Malcolm K.

    2016-01-01

    Rolling element bearings made from highly-elastic intermetallic materials (HIM)s, such as 60NiTi, are under development for applications that require superior corrosion and shock resistance. Compared to steel, intermetallics have been shown to have much lower rolling contact fatigue (RCF) stress capability in simplified 3-ball on rod (ASTM STP 771) fatigue tests. In the 3-ball tests, poor material quality and microstructural flaws negatively affect fatigue life but such relationships have not been established for full-scale 60NiTi bearings. In this paper, 3-ball-on-rod fatigue behavior of two quality grades of 60NiTi are compared to the fatigue life of full-scale 50mm bore ball bearings made from the same materials. 60NiTi RCF rods with material or microstructural flaws suffered from infant mortality failures at all tested stress levels while high quality 60NiTi rods exhibited no failures at lower stress levels. Similarly, tests of full-scale bearings made from flawed materials exhibited early surface fatigue and through crack type failures while bearings made from high quality material did not fail even in long-term tests. Though the full-scale bearing test data is yet preliminary, the results suggest that the simplified RCF test is a good qualitative predictor of bearing performance. These results provide guidance for materials development and to establish minimum quality levels required for successful bearing operation and life.

  10. Effects of Mo ion implantation on rolling contact fatigue behavior of carbon steel

    SciTech Connect

    Yang, D.; Zhou, J.

    1996-11-01

    Rolling Contact Fatigue (RCF) is one of the most serious material surface damage problems encountered by many critical components, especially in ball-bearing applications. RCF is sensitive to the material strength, hardness, surface morphology, microstructure and stress status, which may be dramatically changed by surface modifications. In present work, the surface modification of molybdenum ion implantation into quenched carbon steel was employed, and RCF tests on the implanted specimens, as well as the unimplanted, were performed. It was found out that carbon steel specimens, with and without ion implantation, have the same fatigue damage characteristics. They both have circular and fan-like pits on the fatigue failed surfaces, with many spherical debris existing in the fan-like pits. However, molybdenum ion implantation reduced the rolling contact fatigue life of quenched carbon steel. The possible reasons are the following: the ion beam current is too large, which causes the specimen to undergo the annealing process and soften during the implantation process; the incident angles of ions are different for different spots of curve specimen surface, which causes the uneven distribution of residual stress. These will promote the crack initiation and propagation.

  11. Rolling-Element Bearings

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Anderson, W. J.

    1983-01-01

    Rolling element bearings are a precision, yet simple, machine element of great utility. A brief history of rolling element bearings is reviewed and the type of rolling element bearings, their geometry and kinematics, as well as the materials they are made from and the manufacturing processes they involve are described. Unloaded and unlubricated rolling element bearings, loaded but unlubricated rolling element bearings and loaded and lubricated rolling element bearings are considered. The recognition and understanding of elastohydrodynamic lubrication covered, represents one of the major development in rolling element bearings.

  12. Wind Tunnel Analysis of the Aerodynamic Loads on Rolling Stock over Railway Embankments: The Effect of Shelter Windbreaks

    PubMed Central

    Avila-Sanchez, Sergio; Lopez-Garcia, Oscar; Sanz-Andres, Angel

    2014-01-01

    Wind-flow pattern over embankments involves an overexposure of the rolling stock travelling on them to wind loads. Windbreaks are a common solution for changing the flow characteristic in order to decrease unwanted effects induced by the presence of cross-wind. The shelter effectiveness of a set of windbreaks placed over a railway twin-track embankment is experimentally analysed. A set of two-dimensional wind tunnel tests are undertaken and results corresponding to pressure tap measurements over a section of a typical high-speed train are herein presented. The results indicate that even small-height windbreaks provide sheltering effects to the vehicles. Also, eaves located at the windbreak tips seem to improve their sheltering effect. PMID:25544954

  13. Wind tunnel analysis of the aerodynamic loads on rolling stock over railway embankments: the effect of shelter windbreaks.

    PubMed

    Avila-Sanchez, Sergio; Pindado, Santiago; Lopez-Garcia, Oscar; Sanz-Andres, Angel

    2014-01-01

    Wind-flow pattern over embankments involves an overexposure of the rolling stock travelling on them to wind loads. Windbreaks are a common solution for changing the flow characteristic in order to decrease unwanted effects induced by the presence of cross-wind. The shelter effectiveness of a set of windbreaks placed over a railway twin-track embankment is experimentally analysed. A set of two-dimensional wind tunnel tests are undertaken and results corresponding to pressure tap measurements over a section of a typical high-speed train are herein presented. The results indicate that even small-height windbreaks provide sheltering effects to the vehicles. Also, eaves located at the windbreak tips seem to improve their sheltering effect.

  14. Effect of warm rolling on the martensite transformation temperatures, shape memory effect, and superelasticity in Ti49.2Ni50.8 alloy

    NASA Astrophysics Data System (ADS)

    Lotkov, Aleksander; Zhapova, Dorzhima; Grishkov, Victor; Cherniavsky, Alexander; Timkin, Victor

    2016-11-01

    The paper presents research data demonstrating the effect of warm caliber rolling on the martensite transformation temperatures, shape memory effect, and superelasticity in Ti49.2Ni50.8 (at %). The experimental values of inelastic strain in coarse-grained and microcrystalline Ti49.2Ni50.8 (at %) specimens exceed the theoretical limit of recoverable strain or maximum lattice strain for TiNi-based alloys.

  15. Effective Size of Populations under Selection

    PubMed Central

    Santiago, E.; Caballero, A.

    1995-01-01

    Equations to approximate the effective size (N(e)) of populations under continued selection are obtained that include the possibility of partial full-sib mating and other systems such as assortative mating. The general equation for the case of equal number of sexes and constant number of breeding individuals (N) is N(e) = 4N/[2(1 - α(I)) + (S(k)(2) + 4Q(2)C(2)) (1 + α(I) + 2α(O))], where S(k)(2) is the variance of family size due to sampling without selection, C(2) is the variance of selective advantages among families (the squared coefficient of variation of the expected number of offspring per family), α(I) is the deviation from Hardy-Weinberg proportions, α(O) is the correlation between genes of male and female parents, and Q(2) is the term accounting for the cumulative effect of selection on an inherited trait. This is obtained as Q = 2/[2 - G(1 + r)], where G is the remaining proportion of genetic variance in selected individuals and r is the correlation of the expected selective values of male and female parents. The method is also extended to the general case of different numbers of male and female parents. The predictive value of the formulae is tested under a model of truncation selection with the infinitesimal model of gene effects, where C(2) and G are a function of the selection intensity, the heritability and the intraclass correlation of sibs. Under random mating r = α(I) = -1/(N - 1) and α(O) = 0. Under partial full-sib mating with an average proportion β of full-sib matings per generation, r & β and α(O) & α(I) & β/ (4 - 3β). The prediction equation is compared to other approximations based on the long-term contributions of ancestors to descendants. Finally, based on the approach followed, a system of mating (compensatory mating) is proposed to reduce rates of inbreeding without loss of response in selection programs in which selected individuals from the largest families are mated to those from the smallest families. PMID:7713405

  16. The combined effect of aging and accumulative roll bonding on the evolution of the microstructure and mechanical characteristics of an Al-0.2 wt % Zr alloy

    NASA Astrophysics Data System (ADS)

    Azad, B.; Semnani, H. M.; Borhani, E.

    2017-01-01

    This work is devoted to the effect of processes initiated by the combined action of aging (A) and accumulative roll bonding (ARB) on the evolution of the microstructure and the mechanical characteristics of an Al-0.2 wt % Zr alloy. Upon solution treatment (ST), followed by aging at temperatures of 350 and 450°C, the specimens were subjected to deformation to a degree of deformation of 80% using ARB. The evolution of the microstructure was examined using atomic force microscopy and the mechanical characteristics of the specimens were determined using tensile tests and Vickers microhardness measurements. The results have shown that, upon ten ARB cycles, the grain size decreased to 0.3, 0.4, and 0.32 μm in the specimens subjected to ST followed by ARB (ST-ARB), ST followed by A at a temperature of 350°C and ARB (350°C-A-ARB), and ST followed by A at a temperature of 450°C and ARB (450°C-A-ARB), respectively. This study has also shown that the combined use of preliminary A and subsequent ARB holds promise in enhancing the mechanical characteristics of the alloy due to precipitates that appear in the course of annealing. Fracture surfaces of the rolled specimens subjected to the tensile tests were examined using scanning electron microscopy. The results of these examinations have shown that in the specimens subjected to ST followed by ARB brittle fracture has been observed at the stage of the final ARB cycles, while in the A-ARB specimens cleavage facets (sites of fracture over the cleavage plane) and river lines have appeared on the fracture surfaces.

  17. Common Language Effect Size for Multiple Treatment Comparisons

    ERIC Educational Resources Information Center

    Liu, Xiaofeng Steven

    2015-01-01

    Researchers who need to explain treatment effects to laypeople can translate Cohen's effect size (standardized mean difference) to a common language effect size--a probability of a random observation from one population being larger than a random observation from the other population. This common language effect size can be extended to represent…

  18. Common Language Effect Size for Multiple Treatment Comparisons

    ERIC Educational Resources Information Center

    Liu, Xiaofeng Steven

    2015-01-01

    Researchers who need to explain treatment effects to laypeople can translate Cohen's effect size (standardized mean difference) to a common language effect size--a probability of a random observation from one population being larger than a random observation from the other population. This common language effect size can be extended to represent…

  19. Effects of Different Modes of Hot Cross-Rolling in 7010 Aluminum Alloy: Part II. Mechanical Properties Anisotropy

    NASA Astrophysics Data System (ADS)

    Mondal, Chandan; Singh, A. K.; Mukhopadhyay, A. K.; Chattopadhyay, K.

    2013-06-01

    The influence of microstructure and texture developed by different modes of hot cross-rolling on in-plane anisotropy ( A IP) of yield strength, work hardening behavior, and anisotropy of Knoop hardness (KHN) yield locus has been investigated. The A IP and work hardening behavior are evaluated by tensile testing at 0 deg, 45 deg, and 90 deg to the rolling direction, while yield loci have been generated by directional KHN measurements. It has been observed that specimens especially in the peak-aged temper, in spite of having a strong, rotated Brass texture, show low A IP. The results are discussed on the basis of Schmid factor analyses in conjunction with microstructural features, namely grain morphology and precipitation effects. For the specimen having a single-component texture, the yield strength variation as a function of orientation can be rationalized by the Schmid factor analysis of a perfectly textured material behaving as a quasi-single crystal. The work hardening behavior is significantly affected by the presence of solute in the matrix and the state of precipitation rather than texture, while yield loci derived from KHN measurements reiterate the low anisotropy of the materials. Theoretic yield loci calculated from the texture data using the visco-plastic self-consistent model and Hill's anisotropic equation are compared with that obtained experimentally.

  20. Effects of Calibration Sample Size and Item Bank Size on Ability Estimation in Computerized Adaptive Testing

    ERIC Educational Resources Information Center

    Sahin, Alper; Weiss, David J.

    2015-01-01

    This study aimed to investigate the effects of calibration sample size and item bank size on examinee ability estimation in computerized adaptive testing (CAT). For this purpose, a 500-item bank pre-calibrated using the three-parameter logistic model with 10,000 examinees was simulated. Calibration samples of varying sizes (150, 250, 350, 500,…

  1. Effects of Two-Stage Cold Rolling Schedule on Microstructure and Texture Evolution of Strip Casting Grain-Oriented Silicon Steel with Extra-Low Carbon

    NASA Astrophysics Data System (ADS)

    Song, Hong-Yu; Liu, Hai-Tao; Liu, Wen-Qiang; Wang, Yin-Ping; Liu, Zhen-Yu; Wang, Guo-Dong

    2016-04-01

    A 0.27 mm-thick grain-oriented silicon steel sheet with extra-low carbon was successfully produced by a novel processing route including strip casting, normalizing, two-stage cold rolling with an intermediate annealing, primary annealing, and secondary recrystallization annealing. The evolutions of microstructure and texture along the whole processing route were investigated with a special emphasis on the effects of two-stage cold rolling schedule. It was found that Goss orientation originated in the first cold rolling due to shear banding and relatively strong Goss texture evolved through the whole thickness after intermediate annealing. This is significantly different from the results in conventional process in which the origin of Goss texture is in the hot rolling stage and Goss texture only develops below the sheet surface. Besides, it was found that cold rolling schedule had significant influences on microstructure homogeneity, evolution of λ-fiber texture in primary annealed state and, thus, on secondary recrystallization. In case of appropriate cold rolling schedule, a homogeneous microstructure with Goss texture, relatively strong γ-fiber texture and medium α-fiber texture was observed in the primary annealed strip. Although Goss texture in primary annealed state was much weaker than that in two-stage route in conventional process, a perfect secondary recrystallization microstructure was produced and the magnetic induction B8 was as high as 1.85 T. By contrast, when the cold rolling schedule was inappropriate, the primary annealed strips exhibited inhomogeneous microstructure, together with weak γ-fiber texture, medium α-fiber and λ-fiber texture. Finally, the sheets showed incomplete secondary recrystallization microstructure in which a large number of fine grains still existed.

  2. Effect of rolling-assisted deformation on the formation of an ultrafine-grained structure in a two-phase titanium alloy subjected to severe plastic deformation

    NASA Astrophysics Data System (ADS)

    Demakov, S. L.; Elkina, O. A.; Illarionov, A. G.; Karabanalov, M. S.; Popov, A. A.; Semenova, I. P.; Saitova, L. R.; Shchetnikov, N. V.

    2008-06-01

    The effect of rolling in the temperature range 450 650°C on the fragmentation of the primary phase in a hot-rolled VT6 alloy rod preliminarily subjected to severe plastic deformation by equal-channel angular pressing at 700°C (scheme B c, the angle between the channels is 135°, 12 passes) is studied. Rolling at 450°C without preliminary ECAP is shown not to cause α-phase fragmentation and to favor intense cold working of the alloy due to multiple slip. ECAP provides partial fragmentation of the initial structure of the α phase and changes the morphology of the retained β phase: it transforms from a continuous matrix phase into separated precipitates located between α particles. This transformation activates the fragmentation of the α phase during rolling at 550°C owing to the development of twinning and polygonization processes apart from multiple slip. Both a decrease (to 450°C) and an increase (to 625 650°C) in the rolling temperature as compared to 550°C lead to the formation of a less homogeneous and fragmented structure because of weakly developed recovery and intense cold working in the former case and because of the beginning of recrystallization and the suppression of twinning in the latter case. A relation between the structure that forms upon SPD followed by rolling and the set of its properties is found. A general scheme is proposed for the structural transformations that occur during ECAP followed by rolling at various temperatures.

  3. Effects of extreme pressure additive chemistry on rolling element bearing surface durability

    SciTech Connect

    Evans, Ryan D.; Nixon, H. P.; Darragh, Craig V.; Howe, Jane Y; Coffey, Dorothy W

    2007-01-01

    Lubricant additives have been known to affect rolling element bearing surface durability for many years. Tapered roller bearings were used in fatigue testing of lubricants formulated with gear oil type additive systems. These systems have sulfur- and phosphoruscontaining compounds used for gear protection as well as bearing lubrication. Several variations of a commercially available base additive formulation were tested having modified sulfur components. The variations represent a range of ''active'' extreme pressure (EP) chemistries. The bearing fatigue test results were compared with respect to EP formulation and test conditions. Inner ring near-surface material in selected test bearings was evaluated on two scales: the micrometer scale using optical metallography and the nanometer scale using transmission electron microscopy (TEM). Focused-ion beam (FIB) techniques were used for TEM specimen preparation. Imaging and chemical analysis of the bearing samples revealed near-surface material and tribofilm characteristics. These results are discussed with respect to the relative fatigue lives.

  4. Effect of physisorption and chemisorption of water on resonant modes of rolled-up tubular microcavities

    PubMed Central

    2013-01-01

    Both blue- and redshifts of resonant modes are observed in the rolled-up Y2O3/ZrO2 tubular microcavity during a conformal oxide coating process. Our investigation based on spectral analyses suggests that there are two competitive processes during coating: desorption of both chemically and physically absorbed water molecules and increase of the tube wall thickness. The redshift is due to the increase of the wall thickness and corresponding light confinement enhancement. On the other hand, desorption of water molecules by heating leads to a blueshift. The balance of these two factors produces the observed bi-directional shift of the modes while they both contribute to promoted quality factor after coating. PMID:24344644

  5. Powder lubrication of faults by powder rolls in gouge zones

    NASA Astrophysics Data System (ADS)

    Chen, X.; Madden, A. S.; Reches, Z.

    2013-12-01

    Powder-lubrication by fault gouge can be an effective mechanism of dynamic weakening of faults (Reches & Lockner, 2010); however, the physical mechanisms of this lubrication are poorly understood. While the flow of coarse-grained (> 100 μm) materials, e.g. glass beads or quartz sand, was extensively studied, the flow of fine-grained (< 1 μm) powders, e.g., fault-gouge and nano-powders, have remained enigmatic. We report here experimental results of a new efficient mechanism for powder lubrication. We conducted friction tests on high-velocity rotary shear apparatus (Reches & Lockner, 2010). Two types of experimental faults were tested: (1) faults made of solid, igneous rocks (granite, tonalite and diorite); and (2) fault-zones made of 2-3 mm thick layer of granular materials (oolites, calcite or gypsum) sheared in a confined cell. We performed 21 runs with total slip of 0.14-13 m, normal stress of 1.2-14.5 MPa, slip velocity of 0.012-0.97 m/s. The ultra-microscopic (SEM and AFM) analysis of the experimental slip surfaces revealed two outstanding features in 17 out of the 21 experiments: (1) localized fault-slip along Principal Slip Zones (PSZs) that are composed of a dense, shiny, cohesive crust, 0.5-1 micron thick, that overlaid a porous substrate, and (2) elongated rolls composed of gouge-powder into three-dimensional structures of closely-packed powder grains, (20-50 nm in size). The rolls are cylindrical, 0.75-1.4 micron wide, and 1.7-30 micron long, with smooth outer surface, and laminated, concentric layers of compacted grains. The rolls were exclusively found on the PSZs. Many rolls were destroyed fracturing and smearing on the PSZ, suggesting that the rolls underwent a life cycle of formation and destruction. Significant macroscopic friction reduction was measured in experiments with observed rolls, and no (or minor) friction reduction in the four experiments without rolls. The final, reduced friction coefficients have a general reciprocal relation to the

  6. [Effect sizes, statistical power and sample sizes in "the Japanese Journal of Psychology"].

    PubMed

    Suzukawa, Yumi; Toyoda, Hideki

    2012-04-01

    This study analyzed the statistical power of research studies published in the "Japanese Journal of Psychology" in 2008 and 2009. Sample effect sizes and sample statistical powers were calculated for each statistical test and analyzed with respect to the analytical methods and the fields of the studies. The results show that in the fields like perception, cognition or learning, the effect sizes were relatively large, although the sample sizes were small. At the same time, because of the small sample sizes, some meaningful effects could not be detected. In the other fields, because of the large sample sizes, meaningless effects could be detected. This implies that researchers who could not get large enough effect sizes would use larger samples to obtain significant results.

  7. Effect of Inertial Force on Thermal Elastohydrodynamic Lubrication of Oil Film Bearing in Rolling Mill Lubricated by the Oil-water Two-phase Flow

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Wang, You-Qiang; Wang, Jian; Fan, Xiao-Meng

    2016-05-01

    The oil film bearing in rolling mill as the research object in this paper is established oilwater two-phase flow of thermal elastohydrodynamic lubrication (EHL) model with the inertia force and thermal effect of the Reynolds equation. The oil film bearing in rolling mill in oil-water two-phase flow is analyzed the effect on the pyrolysis with considering inertia force, and the lubricant film pressure, film thickness with the changes in the relationship between water content, rolling force and spindle speed. The results showed that the lubricant film thickness is increased and carrying capacity is also increased with considering inertial force. With the increase of water content, lubricant film thickness is increased and the carrying capacity is decreased.

  8. A comparative study of roll compaction of free-flowing and cohesive pharmaceutical powders.

    PubMed

    Yu, Shen; Gururajan, Bindhu; Reynolds, Gavin; Roberts, Ron; Adams, Michael J; Wu, Chuan-Yu

    2012-05-30

    Roll compaction is widely adopted as a dry granulation method in the pharmaceutical industry. The roll compaction behaviour of feed powders is primarily governed by two parameters: the maximum pressure and the nip angle. Although the maximum pressure can be measured directly using pressure sensors fitted in the rolls, it is not a trivial task to determine the nip angle, which is a measure of the size of the compaction zone and hence the degree of compression. Thus a robust approach based upon the calculation of the pressure gradient, which can be obtained directly from experiments using an instrumented roll compactor, was developed. It has been shown that the resulting nip angles are comparable to those obtained using the methods reported in literature. Nevertheless, the proposed approach has distinctive advantages including (1) it is based on the intrinsic features of slip and no-slip interactions between the powder and roll surface and (2) it is not necessary to carry out wall friction measurements that involve plates that may not be representative of the roll compactor in terms of the surface topography and surface energy. The method was evaluated by investigating the effect of roll speed for two pharmaceutical excipients with distinctive material properties: microcrystalline cellulose (MCC) and di-calcium phosphate dihydrate (DCPD). It was found that the maximum pressure and nip angle for DCPD, which is a cohesive powder, decrease sharply with increasing roll speed whereas they are essentially independent of roll speed for MCC, which is an easy flowing powder. The roll compaction behaviour of MCC-DCPD mixtures with various compositions was also investigated in order to evaluate the effect of flowability. It was found that the nip angle and maximum pressure generally increased with improved flowability of the feed powders.

  9. Effect of the Ultrasonic Surface Rolling Process on the Fretting Fatigue Behavior of Ti-6Al-4V Alloy

    PubMed Central

    Liu, Chengsong; Liu, Daoxin; Zhang, Xiaohua; Yu, Shouming; Zhao, Weidong

    2017-01-01

    The effect of the ultrasonic surface rolling process (USRP) on the rotary bending fretting fatigue (FF) of Ti-6Al-4V alloy was investigated. The reason for the USRP’s ability to improve the FF resistance of Ti-6Al-4V alloy was studied. The results revealed that the USRP induced a compressive residual stress field with a depth of 530 μm and a maximum residual stress of −930 MPa. Moreover, the surface micro-hardness of the USRP sample was significantly higher than that of the untreated base material (BM) sample, and the USRP yielded a 72.7% increase in the FF limit of the alloy. These further enhanced fatigue properties contributed mainly to the compressive residual stress field with large numerical value and deep distribution, which could effectively suppress FF crack initiation and early propagation. The USRP-induced surface work-hardening had only a minor impact on the FF resistance. PMID:28773192

  10. Effect of the Ultrasonic Surface Rolling Process on the Fretting Fatigue Behavior of Ti-6Al-4V Alloy.

    PubMed

    Liu, Chengsong; Liu, Daoxin; Zhang, Xiaohua; Yu, Shouming; Zhao, Weidong

    2017-07-20

    The effect of the ultrasonic surface rolling process (USRP) on the rotary bending fretting fatigue (FF) of Ti-6Al-4V alloy was investigated. The reason for the USRP's ability to improve the FF resistance of Ti-6Al-4V alloy was studied. The results revealed that the USRP induced a compressive residual stress field with a depth of 530 μm and a maximum residual stress of -930 MPa. Moreover, the surface micro-hardness of the USRP sample was significantly higher than that of the untreated base material (BM) sample, and the USRP yielded a 72.7% increase in the FF limit of the alloy. These further enhanced fatigue properties contributed mainly to the compressive residual stress field with large numerical value and deep distribution, which could effectively suppress FF crack initiation and early propagation. The USRP-induced surface work-hardening had only a minor impact on the FF resistance.

  11. How to Estimate and Interpret Various Effect Sizes

    ERIC Educational Resources Information Center

    Vacha-Haase, Tammi; Thompson, Bruce

    2004-01-01

    The present article presents a tutorial on how to estimate and interpret various effect sizes. The 5th edition of the Publication Manual of the American Psychological Association (2001) described the failure to report effect sizes as a "defect" (p. 5), and 23 journals have published author guidelines requiring effect size reporting. Although…

  12. How to Estimate and Interpret Various Effect Sizes

    ERIC Educational Resources Information Center

    Vacha-Haase, Tammi; Thompson, Bruce

    2004-01-01

    The present article presents a tutorial on how to estimate and interpret various effect sizes. The 5th edition of the Publication Manual of the American Psychological Association (2001) described the failure to report effect sizes as a "defect" (p. 5), and 23 journals have published author guidelines requiring effect size reporting. Although…

  13. When Effect Sizes Disagree: The Case of "r" and "d"

    ERIC Educational Resources Information Center

    McGrath, Robert E.; Meyer, Gregory J.

    2006-01-01

    The increased use of effect sizes in single studies and meta-analyses raises new questions about statistical inference. Choice of an effect-size index can have a substantial impact on the interpretation of findings. The authors demonstrate the issue by focusing on two popular effect-size measures, the correlation coefficient and the…

  14. Reporting and Discussing Effect Size: Still the Road Less Traveled?

    ERIC Educational Resources Information Center

    McMillan, James H.; Foley, Jennifer

    2011-01-01

    This study shows the extent to which effect size is reported and discussed in four major journals. A series of judgments about different aspects of effect size were conducted for 417 articles from four journals. Results suggest that while the reporting of simple effect size indices is more prevalent, substantive discussions of the meaning of…

  15. Reporting and Discussing Effect Size: Still the Road Less Traveled?

    ERIC Educational Resources Information Center

    McMillan, James H.; Foley, Jennifer

    2011-01-01

    This study shows the extent to which effect size is reported and discussed in four major journals. A series of judgments about different aspects of effect size were conducted for 417 articles from four journals. Results suggest that while the reporting of simple effect size indices is more prevalent, substantive discussions of the meaning of…

  16. System-Size Effects in Metastability

    NASA Astrophysics Data System (ADS)

    Schulman, L. S.

    The following sections are included: * INTRODUCTION * CALCULATION OP PV(m), THE FINITE) SIZE PROBABILITY FOR FINDING MAGNETIZATION m * HEURISTICS OF PV(m) * DYNAMIC METASTABILITY * DISCUSSION * ACKNOWLEDGEMENTS * REFERENCES

  17. Roll compaction/dry granulation: comparison between roll mill and oscillating granulator in dry granulation.

    PubMed

    Sakwanichol, Jarunee; Puttipipatkhachorn, Satit; Ingenerf, Gernot; Kleinebudde, Peter

    2012-01-01

    Different experimental factorial designs were employed to evaluate granule properties obtained from oscillating granulator and roll mill. Four oscillating-granulator parameters were varied, i.e. rotor speed, oscillating angle, aperture of mesh screen and rotor type. Six roll-mill parameters that were throughput, speed ratio in both first and second stages, gap between roll pair in both stages and roll-surface texture were also investigated. Afterwards, the granule properties obtained from two milling types with similar median particle size were compared. All milling parameters in both milling types affected significantly the median particle size, size distribution and amount of fine particles (P < 0.05), except the rotor types of oscillating granulator on fines. Only three milling parameters influenced significantly the flowability (P < 0.05). These were the throughput and the gap size in the first stage of roll mill and the sieve size of oscillating granulator. In comparison between milling types, the differences of granule properties were not practically relevant. However, the roll mill had much higher capacity than the oscillating granulator about seven times, resulting in improving energy savings per unit of product. Consequently, the roll mill can be applied instead of oscillating granulator for roll compaction/dry granulation technique.

  18. Size Effect on Magnesium Alloy Castings

    NASA Astrophysics Data System (ADS)

    Li, Zhenming; Wang, Qigui; Luo, Alan A.; Zhang, Peng; Peng, Liming

    2016-06-01

    The effect of grain size on tensile and fatigue properties has been investigated in cast Mg alloys of Mg-2.98Nd-0.19Zn (1530 μm) and Mg-2.99Nd-0.2Zn-0.51Zr (41 μm). The difference between RB and push-pull fatigue testing was also evaluated in both alloys. The NZ30K05-T6 alloy shows much better tensile strengths (increased by 246 pct in YS and 159 pct in UTS) and fatigue strength (improved by ~80 pct) in comparison with NZ30-T6 alloy. RB fatigue testing results in higher fatigue strength compared with push-pull fatigue testing, mainly due to the stress/strain gradient in the RB specimen cross section. The material with coarse grains could be hardened more in the cyclic loading condition than in the monotonic loading condition, corresponding to the lower σ f and the higher σ f/ σ b or σ f/ σ 0.2 ratio compared to the materials with fine grains. The fatigue crack initiation sites and failure mechanism are mainly determined by the applied stress/strain amplitude. In LCF, fatigue failure mainly originates from the PSBs within the surface or subsurface grains of the samples. In HCF, cyclic deformation and damage irreversibly caused by environment-assisted cyclic slip is the crucial factor to influence the fatigue crack. The Coffin-Manson law and Basquin equation, and the developed MSF models and fatigue strength models can be used to predict fatigue lives and fatigue strengths of cast magnesium alloys.

  19. The cost of large numbers of hypothesis tests on power, effect size and sample size.

    PubMed

    Lazzeroni, L C; Ray, A

    2012-01-01

    Advances in high-throughput biology and computer science are driving an exponential increase in the number of hypothesis tests in genomics and other scientific disciplines. Studies using current genotyping platforms frequently include a million or more tests. In addition to the monetary cost, this increase imposes a statistical cost owing to the multiple testing corrections needed to avoid large numbers of false-positive results. To safeguard against the resulting loss of power, some have suggested sample sizes on the order of tens of thousands that can be impractical for many diseases or may lower the quality of phenotypic measurements. This study examines the relationship between the number of tests on the one hand and power, detectable effect size or required sample size on the other. We show that once the number of tests is large, power can be maintained at a constant level, with comparatively small increases in the effect size or sample size. For example at the 0.05 significance level, a 13% increase in sample size is needed to maintain 80% power for ten million tests compared with one million tests, whereas a 70% increase in sample size is needed for 10 tests compared with a single test. Relative costs are less when measured by increases in the detectable effect size. We provide an interactive Excel calculator to compute power, effect size or sample size when comparing study designs or genome platforms involving different numbers of hypothesis tests. The results are reassuring in an era of extreme multiple testing.

  20. Effect of Coiling Temperature on Microstructure and Tensile Behavior of a Hot-Rolled Ferritic Lightweight Steel

    NASA Astrophysics Data System (ADS)

    Wang, Junfeng; Yang, Qi; Wang, Xiaodong; Wang, Li

    2016-12-01

    Effects of coiling temperature (CT) ranging from 673 K to 973 K (400 °C to 700 °C) on microstructure and tensile property of a hot-rolled ferritic lightweight steel containing 0.35 wt pct C and 4.1 wt pct Al are investigated in the present study. Basically, the microstructure of the hot-rolled steel is composed of δ-ferrite grain bands and secondary phase bands which are originated from the decomposition of antecedent austenite. The secondary phase band is a bainite band at coiling temperatures (CTs) lower than 723 K (450 °C). More specifically, the bainite band mainly consists of lower bainite together with blocky retained austenite at the CT of 673 K (400 °C), while it primarily contains carbide-free bainite being an aggregate of lath-shaped ferrite and austenite at the CT of 723 K (450 °C). The secondary phase band is a carbide band which mainly contains a pearlite structure at CTs higher than 773 K (500 °C). There are three types of carbides in the steel matrix: transitional ɛ-carbide present inside lower bainite, cementite present within carbide bands as well as at the boundaries between carbide bands and δ-ferrite bands, and κ-carbide present at δ-ferrite grain boundaries which is clearly seen at CTs higher than 773 K (500 °C). The volume fraction of retained austenite reaches the peak value of 9.6 pct at the CT of 723 K (450 °C), and abruptly drops to zero when the CTs are higher than 773 K (500 °C). Lath-shaped retained austenite with a higher volume fraction induces significant enhancement of elongation through the TRIP effect, leading to a uniform elongation of 25 pct and an elongation-to-failure of 32 pct at the CT of 723 K (450 °C). Crack initiation and propagation inside the tested specimens are tracked and fracture surface is observed to help understand the deformation and fracture behavior of the hot-rolled steel.

  1. Causality in Statistical Power: Isomorphic Properties of Measurement, Research Design, Effect Size, and Sample Size

    PubMed Central

    Heidel, R. Eric

    2016-01-01

    Statistical power is the ability to detect a significant effect, given that the effect actually exists in a population. Like most statistical concepts, statistical power tends to induce cognitive dissonance in hepatology researchers. However, planning for statistical power by an a priori sample size calculation is of paramount importance when designing a research study. There are five specific empirical components that make up an a priori sample size calculation: the scale of measurement of the outcome, the research design, the magnitude of the effect size, the variance of the effect size, and the sample size. A framework grounded in the phenomenon of isomorphism, or interdependencies amongst different constructs with similar forms, will be presented to understand the isomorphic effects of decisions made on each of the five aforementioned components of statistical power. PMID:27073717

  2. Causality in Statistical Power: Isomorphic Properties of Measurement, Research Design, Effect Size, and Sample Size.

    PubMed

    Heidel, R Eric

    2016-01-01

    Statistical power is the ability to detect a significant effect, given that the effect actually exists in a population. Like most statistical concepts, statistical power tends to induce cognitive dissonance in hepatology researchers. However, planning for statistical power by an a priori sample size calculation is of paramount importance when designing a research study. There are five specific empirical components that make up an a priori sample size calculation: the scale of measurement of the outcome, the research design, the magnitude of the effect size, the variance of the effect size, and the sample size. A framework grounded in the phenomenon of isomorphism, or interdependencies amongst different constructs with similar forms, will be presented to understand the isomorphic effects of decisions made on each of the five aforementioned components of statistical power.

  3. Standardized or simple effect size: what should be reported?

    PubMed

    Baguley, Thom

    2009-08-01

    It is regarded as best practice for psychologists to report effect size when disseminating quantitative research findings. Reporting of effect size in the psychological literature is patchy - though this may be changing - and when reported it is far from clear that appropriate effect size statistics are employed. This paper considers the practice of reporting point estimates of standardized effect size and explores factors such as reliability, range restriction and differences in design that distort standardized effect size unless suitable corrections are employed. For most purposes simple (unstandardized) effect size is more robust and versatile than standardized effect size. Guidelines for deciding what effect size metric to use and how to report it are outlined. Foremost among these are: (i) a preference for simple effect size over standardized effect size, and (ii) the use of confidence intervals to indicate a plausible range of values the effect might take. Deciding on the appropriate effect size statistic to report always requires careful thought and should be influenced by the goals of the researcher, the context of the research and the potential needs of readers.

  4. Biofuel manufacturing from woody biomass: effects of sieve size used in biomass size reduction.

    PubMed

    Zhang, Meng; Song, Xiaoxu; Deines, T W; Pei, Z J; Wang, Donghai

    2012-01-01

    Size reduction is the first step for manufacturing biofuels from woody biomass. It is usually performed using milling machines and the particle size is controlled by the size of the sieve installed on a milling machine. There are reported studies about the effects of sieve size on energy consumption in milling of woody biomass. These studies show that energy consumption increased dramatically as sieve size became smaller. However, in these studies, the sugar yield (proportional to biofuel yield) in hydrolysis of the milled woody biomass was not measured. The lack of comprehensive studies about the effects of sieve size on energy consumption in biomass milling and sugar yield in hydrolysis process makes it difficult to decide which sieve size should be selected in order to minimize the energy consumption in size reduction and maximize the sugar yield in hydrolysis. The purpose of this paper is to fill this gap in the literature. In this paper, knife milling of poplar wood was conducted using sieves of three sizes (1, 2, and 4 mm). Results show that, as sieve size increased, energy consumption in knife milling decreased and sugar yield in hydrolysis increased in the tested range of particle sizes.

  5. Biofuel Manufacturing from Woody Biomass: Effects of Sieve Size Used in Biomass Size Reduction

    PubMed Central

    Zhang, Meng; Song, Xiaoxu; Deines, T. W.; Pei, Z. J.; Wang, Donghai

    2012-01-01

    Size reduction is the first step for manufacturing biofuels from woody biomass. It is usually performed using milling machines and the particle size is controlled by the size of the sieve installed on a milling machine. There are reported studies about the effects of sieve size on energy consumption in milling of woody biomass. These studies show that energy consumption increased dramatically as sieve size became smaller. However, in these studies, the sugar yield (proportional to biofuel yield) in hydrolysis of the milled woody biomass was not measured. The lack of comprehensive studies about the effects of sieve size on energy consumption in biomass milling and sugar yield in hydrolysis process makes it difficult to decide which sieve size should be selected in order to minimize the energy consumption in size reduction and maximize the sugar yield in hydrolysis. The purpose of this paper is to fill this gap in the literature. In this paper, knife milling of poplar wood was conducted using sieves of three sizes (1, 2, and 4 mm). Results show that, as sieve size increased, energy consumption in knife milling decreased and sugar yield in hydrolysis increased in the tested range of particle sizes. PMID:22665985

  6. Effects of recurrent rolling/crimping operations on cover crop termination, soil moisture, and soil strength for conservation organic systems

    USDA-ARS?s Scientific Manuscript database

    Rolling/crimping technology has been utilized to mechanically terminate cover crops in conservation agriculture. In the southeastern United States, to eliminate competition for valuable soil moisture, three weeks are typically required after rolling to plant a cash crop into the desiccated cover cro...

  7. Effect of cold rolling on microstructure and mechanical property of extruded Mg–4Sm alloy during aging

    SciTech Connect

    Li, Rongguang; Xin, Renlong; Chapuis, Adrien; Liu, Qing; Fu, Guangyan; Zong, Lin; Yu, Yongmei; Guo, Beitao; Guo, Shuguo

    2016-02-15

    Microstructure and mechanical properties of the Mg–4Sm (wt.%) alloy, prepared via combined processes of extrusion, cold rolling and aging, have been investigated. The hot extruded alloy exhibits a weak rare earth magnesium alloy texture with < 11 − 21 >//ED, while the cold-rolled alloy shows a stronger basal texture with < 0001 >//ND. Many tensile twins and double twins are observed in grains after rolling. The cold-rolled alloy shows a weak age-hardening response compared with the extruded alloy, which is the result of more precipitation in the twin boundary during aging. The rolled alloy exhibits almost no precipitate free zone during aging compared with the extruded alloy. The higher proof stress of the rolled alloy in peak-aged condition is attributed to the presence of twin boundaries, stronger basal texture, higher dislocation density, and the suppression of precipitate free zone compared with the extruded alloy. - Highlights: • No precipitate free zone appears in cold-rolled alloy after aging. • Segregation and precipitates are observed in twin boundaries and grain boundaries. • Cold-rolled alloy shows a weak age-hardening response.

  8. Effect of the residual near-surface stresses of the working surface on the contact resistance of rolls

    NASA Astrophysics Data System (ADS)

    Rusakov, A. D.

    2010-05-01

    The results of contact resistance tests of roll steel samples with various levels of near-surface residual compressive stresses are analyzed. A relation between these stresses and the contact resistance is found. Recommendations are made for the formation of rational near-surface residual stresses in the active surfaces of rolls in order to increase their resistance.

  9. Effect of Prior Recovery Treatment on the Evolution of Cube Texture During Annealing of Severely Warm-Rolled Al-2.5 wt pctMg Alloy

    NASA Astrophysics Data System (ADS)

    Gatti, J. R.; Bhattacharjee, Pinaki Prasad

    2015-11-01

    The effect of prior recovery on the evolution of cube texture ({001}<100>) in severely warm-rolled and annealed Al-2.5 wt pctMg alloy was studied. The Al-2.5 wt pctMg alloy was warm rolled to 97 pct reduction in thickness at 473 K (200 °C). The warm-rolled sheets were isochronally annealed for 1 hour at temperatures ranging from 523 K to 673 K (250 °C to 400 °C) without and with prior recovery treatments. In case of prior recovery, the sheets were pre-treated at 473 K (200 °C) for different time intervals ranging from 3.6 × 103 seconds (1 hour) to 8.64 × 104 seconds (24 hours) before the annealing. The warm-rolled alloy showed finely subdivided lamellar structure and strong presence of pure metal type texture. The annealed materials without any prior recovery treatment showed strong cube texture after annealing which could be attributed to the oriented nucleation of cube grains resulting from the preferentially recovered structure of cube regions in the warm-rolled state. In contrast, the cube texture was significantly weakened in materials subjected to different prior recovery treatments. The prior recovery treatments resulted in homogenous recovery which was confirmed by microstructural, textural, and conductivity measurements. Homogenous recovery eliminated the nucleation advantage of cube regions originating from the preferentially recovered structure and weakened the cube texture significantly. The present results indicated that prior recovery treatment could be effectively used to control recrystallization cube texture in severely warm-rolled aluminum alloys.

  10. Acute Effects of Foam Rolling, Static Stretching, and Dynamic Stretching During Warm-Ups on Muscular Flexibility and Strength in Young Adults.

    PubMed

    Su, Hsuan; Chang, Nai-Jen; Wu, Wen-Lan; Guo, Lan-Yuen; Chu, I-Hua

    2016-10-13

    Foam rolling has been proposed to improve muscle function, performance, and joint range of motion (ROM). However, whether a foam rolling protocol can be adopted as a warm-up to improve flexibility and muscle strength is unclear. To examine and compare the acute effects of foam rolling, static stretching, and dynamic stretching used as part of warm-up on flexibility and muscle strength of knee flexion and extension. Crossover study. University research laboratory. 15 male and 15 female college students (age 21.43 ± 1.48 y, weight 65.13 ± 12.29 kg, height 166.90 ± 6.99 cm). Isokinetic peak torque was measured during knee extension and flexion at an angular velocity of 60°/second. Flexibility of the quadriceps was assessed by the modified Thomas test, while flexibility of hamstrings was assessed using the sit-and-reach test. The 3 interventions were performed by all participants in random order on 3 days separated by 48-72 hours. The flexibility test scores improved significantly more after foam rolling as compared to static and dynamic stretching. With regard to muscle strength, only knee extension peak torque (pre vs. post intervention) improved significantly after the dynamic stretching and foam rolling, but not after static stretching. Knee flexion peak torque remained unchanged. Foam rolling is more effective than static and dynamic stretching in acutely increasing flexibility of the quadriceps and hamstrings without hampering muscle strength, and may be recommended as part of a warm-up in healthy young adults.

  11. Effect of Cookery and Holding on Hams and Turkey Rolls Contaminated with Clostridium perfringens1

    PubMed Central

    Strong, Dorothy H.; Ripp, Nancy M.

    1967-01-01

    Canned hams, turkey rolls, and ground-beef casseroles were inoculated with a mixture of vegetative cells and spores of selected strains of Clostridium perfringens, in approximately known numbers. After cooking and holding at different temperatures for various times, samples of the food were plated directly on sulfadiazine-polymixin-sulfite-agar. In all cases, small but measurable percentages of the organisms survived cookery. The number of cells viable after cookery of the ham or turkey was influenced by the position of the slice of meat in the roast as well as by the final temperature to which the product was heated. Plate counts for turkey or beef casserole held at temperatures in the range of 5 to 10 C for 48 hr indicated stabilization of the population or a tendency to decrease. At 24 C, the multiplication of cells was apparent in 4 hr and rapid in 6 hr. When the food was maintained at 68 C, populations remained viable for 6 hr and the counts did not change markedly. In turkey maintained at 37 C, the number of cells increased sharply within 4 hr. PMID:4294821

  12. Interpreting and Reporting Effect Sizes in Research Investigations.

    ERIC Educational Resources Information Center

    Tapia, Martha; Marsh, George E., II

    Since 1994, the American Psychological Association (APA) has advocated the inclusion of effect size indices in reporting research to elucidate the statistical significance of studies based on sample size. In 2001, the fifth edition of the APA "Publication Manual" stressed the importance of including an index of effect size to clarify…

  13. Avoiding Decision-Making by Chance: Protecting Effect Size Estimates.

    ERIC Educational Resources Information Center

    Barnette, J. Jackson; McLean, James E.

    The probabilities of attaining varying magnitudes of standardized effect sizes by chance and when protected by a 0.05 level statistical test were studied. Monte Carlo procedures were used to generate standardized effect sizes in a one-way analysis of variance situation with 2 through 5, 6, 8, and 10 groups with selected sample sizes from 5 to 500.…

  14. Effect of tire size on skidder productivity

    Treesearch

    Richard W. Brinker; John F. Klepac; Bryce J. Stokes; Joe D. Roberson

    1996-01-01

    During the spring of 1996 a collaborative effort among Mead Coated Board, the Auburn University School of Forestry, and the Southern Research Station was initiated to evaluate skidder production performance as a function of tire size and soil condition (i.e., wet and dry season). The objective of the study was to determine production and cost differences among 28L-26,...

  15. Size Effect in Ferroelectric Long Cylinders

    NASA Astrophysics Data System (ADS)

    Wang, Yuguo; Zhang, Peilin; Wang, Chunlei; Zhong, Weilie; N, Napp; D, R. Tilly

    1995-02-01

    The Curie temperature and polarization in a ferroelectric cylinder with infinite length have been examined using Landau free energy expansion. The Curie temperature and polarization decrease with decreasing cylinder diameter for the positive extrapolation length, and reach zero at the critical size. For negative extrapolation length, both Curie temperature and polarization increase with decreasing cylinder diameter.

  16. Phase Doppler droplet sizing: Scattering angle effects

    SciTech Connect

    Ceman, D.L.; O'Hern, T.J.; Rader, D.J.

    1990-01-01

    The phase Doppler technique is an LDV-based method for the nonintrusive, simultaneous measurement of particle size, velocity, and concentration. It is becoming a standard device for measurement of spray droplets in air as well as cavitation nuclei bubbles in water. The Phase Doppler Particle Analyzer (PDPA) is a commercial phase Doppler instrument. Previous calibrations of the PDPA using well-characterized liquid droplets have revealed nonlinearity of the instrument response for droplet diameters less than 20 {mu}m. For many applications, droplet sizing accuracy in the small diameter range is critical. Light scattering calculations performed by the instrument manufacturer suggest two theoretical approaches to improving the instrument response in this size range: optimizing the collection angle and increasing the collection area. The first approach has been tested experimentally. This paper presents size calibrations of the PDPA with the receiver configured at two angles: 30{degree} (the standard configuration) and 70{degree} off-forward axis. The calibration was performed with monodisperse oleic acid droplets in the diameter range 3.7 to 32 {mu}m. As in earlier calibration studies, the 30{degree} configuration resulted in marked nonlinearity in instrument response below 20 {mu}m. Oscillations were still apparent for the 70{degree} configuration, which showed only a modest improvement compared to the response at 30{degree}. 7 refs., 5 figs.

  17. Rolling-Contact Rheostat

    NASA Technical Reports Server (NTRS)

    Ruoff, C. F.

    1985-01-01

    Contact noise in rheostats and potentiometers reduced by rolling contact design. Smooth rolling action eliminates sporadic variations in resistance caused by bouncing and stick/slip motion of conventional sliding contacts.

  18. 4. ROLL LATHE OF THE MAIN ROLL SHOP. THE LATHE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. ROLL LATHE OF THE MAIN ROLL SHOP. THE LATHE WAS CLOSED WITH TWO ROLLS IN PLACE, AND THE LOWER ROLL WAS TURNED TO MATCH THE UPPER ROLL. - U.S. Steel Homestead Works, Main Roll Shop, Along Monongahela River, Homestead, Allegheny County, PA

  19. Testing Multivariate Effect Sizes in Multiple-Endpoint Studies.

    ERIC Educational Resources Information Center

    Timm, Neil H.

    1999-01-01

    Investigates the equality of "p" correlated effect sizes for "k" independent studies in which treatment and control groups are compared using Hotelling's "T" statistic. Illustrates the procedure and discusses the importance of sample size. (SLD)

  20. Effect of Frying Conditions and Yeast Fermentation on the Acrylamide Content in You-Tiao, a Traditional Chinese Fried Twisted Dough-roll

    USDA-ARS?s Scientific Manuscript database

    Effects of frying temperature, frying time and dough pH on the formation of acrylamide in the processing of you-tiao, a traditional Chinese fried twisted dough-roll, were analyzed using response surface methodology. The results obtained showed that the frying temperature and time had a notable impa...

  1. The pack size effect: Influence on consumer perceptions of portion sizes.

    PubMed

    Hieke, Sophie; Palascha, Aikaterini; Jola, Corinne; Wills, Josephine; Raats, Monique M

    2016-01-01

    Larger portions as well as larger packs can lead to larger prospective consumption estimates, larger servings and increased consumption, described as 'portion-size effects' and 'pack size effects'. Although related, the effects of pack sizes on portion estimates have received less attention. While it is not possible to generalize consumer behaviour across cultures, external cues taken from pack size may affect us all. We thus examined whether pack sizes influence portion size estimates across cultures, leading to a general 'pack size effect'. We compared portion size estimates based on digital presentations of different product pack sizes of solid and liquid products. The study with 13,177 participants across six European countries consisted of three parts. Parts 1 and 2 asked participants to indicate the number of portions present in a combined photographic and text-based description of different pack sizes. The estimated portion size was calculated as the quotient of the content weight or volume of the food presented and the number of stated portions. In Part 3, participants stated the number of food items that make up a portion when presented with packs of food containing either a small or a large number of items. The estimated portion size was calculated as the item weight times the item number. For all three parts and across all countries, we found that participants' portion estimates were based on larger portions for larger packs compared to smaller packs (Part 1 and 2) as well as more items to make up a portion (Part 3); hence, portions were stated to be larger in all cases. Considering that the larger estimated portions are likely to be consumed, there are implications for energy intake and weight status.

  2. Internal roll compression system

    DOEpatents

    Anderson, Graydon E.

    1985-01-01

    This invention is a machine for squeezing water out of peat or other material of low tensile strength; the machine including an inner roll eccentrically positioned inside a tubular outer roll, so as to form a gradually increasing pinch area at one point therebetween, so that, as the rolls rotate, the material is placed between the rolls, and gets wrung out when passing through the pinch area.

  3. Acute effects of anterior thigh foam rolling on hip angle, knee angle, and rectus femoris length in the modified Thomas test.

    PubMed

    Vigotsky, Andrew D; Lehman, Gregory J; Contreras, Bret; Beardsley, Chris; Chung, Bryan; Feser, Erin H

    2015-01-01

    Background. Foam rolling has been shown to acutely increase range of motion (ROM) during knee flexion and hip flexion with the experimenter applying an external force, yet no study to date has measured hip extensibility as a result of foam rolling with controlled knee flexion and hip extension moments. The purpose of this study was to investigate the acute effects of foam rolling on hip extension, knee flexion, and rectus femoris length during the modified Thomas test. Methods. Twenty-three healthy participants (male = 7; female = 16; age = 22 ± 3.3 years; height = 170 ± 9.18 cm; mass = 67.7 ± 14.9 kg) performed two, one-minute bouts of foam rolling applied to the anterior thigh. Hip extension and knee flexion were measured via motion capture before and after the foam rolling intervention, from which rectus femoris length was calculated. Results. Although the increase in hip extension (change = +1.86° (+0.11, +3.61); z(22) = 2.08; p = 0.0372; Pearson's r = 0.43 (0.02, 0.72)) was not due to chance alone, it cannot be said that the observed changes in knee flexion (change = -1.39° (-5.53, +2.75); t(22) = -0.70; p = 0.4933; Cohen's d = - 0.15 (-0.58, 0.29)) or rectus femoris length (change = -0.005 (-0.013, +0.003); t(22) = -1.30; p = 0.2070; Cohen's d = - 0.27 (-0.70, 0.16)) were not due to chance alone. Conclusions. Although a small change in hip extension was observed, no changes in knee flexion or rectus femoris length were observed. From these data, it appears unlikely that foam rolling applied to the anterior thigh will improve passive hip extension and knee flexion ROM, especially if performed in combination with a dynamic stretching protocol.

  4. Effect size estimates: current use, calculations, and interpretation.

    PubMed

    Fritz, Catherine O; Morris, Peter E; Richler, Jennifer J

    2012-02-01

    The Publication Manual of the American Psychological Association (American Psychological Association, 2001, American Psychological Association, 2010) calls for the reporting of effect sizes and their confidence intervals. Estimates of effect size are useful for determining the practical or theoretical importance of an effect, the relative contributions of factors, and the power of an analysis. We surveyed articles published in 2009 and 2010 in the Journal of Experimental Psychology: General, noting the statistical analyses reported and the associated reporting of effect size estimates. Effect sizes were reported for fewer than half of the analyses; no article reported a confidence interval for an effect size. The most often reported analysis was analysis of variance, and almost half of these reports were not accompanied by effect sizes. Partial η2 was the most commonly reported effect size estimate for analysis of variance. For t tests, 2/3 of the articles did not report an associated effect size estimate; Cohen's d was the most often reported. We provide a straightforward guide to understanding, selecting, calculating, and interpreting effect sizes for many types of data and to methods for calculating effect size confidence intervals and power analysis.

  5. A Meta Analytical Approach Regarding School Effectiveness: The True Size of School Effects and the Effect Size of Educational Leadership.

    ERIC Educational Resources Information Center

    Bosker, Roel J.; Witziers, Bob

    School-effectiveness research has not yet been able to identify the factors of effective and noneffective schools, the real contribution of the significant factors, the true sizes of school effects, and the generalizability of school-effectiveness results. This paper presents findings of a meta analysis, the Dutch PSO programme, that was used to…

  6. Effect of cold rolling and first precipitates on the coarsening behavior of γ″-phases in Inconel 718 alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Jing-ling; Guo, Qian-ying; Liu, Yong-chang; Li, Chong; Yu, Li-ming; Li, Hui-jun

    2016-09-01

    The coarsening behaviors of γ″-phase particles in Inconel 718 alloy aged at 750, 800, and 850°C were investigated by scanning electron microscopy (SEM). Detailed observations and quantitative measurements were conducted to characterize the coarsening behavior of the γ?-phase under various aging conditions. The experimental results indicate that the existence of the δ-phase retards the formation and coarsening of the γ″-phase, without influencing its final particle size or amount. Moreover, when cold rolled with a reduction of 50%, the dimensions of the γ″ particles in Inconel 718 alloy decrease with increasing aging time. Furthermore, the coarsening behavior of the γ″-phase in the Inconel 718 alloy after a normal aging treatment (sample A) and that of the primary δ-phase (sample B) follow the Lifshitz-Slyozov-Wagner (LSW) diffusion-controlled growth theory; the thus-obtained activation energies for the γ″-phase are 292 kJ·mol-1 and 302 kJ·mol-1, respectively.

  7. Determination of the Effect of Wing Flexibility on Lateral Maneuverability and a Comparison of Calculated Rolling Effectiveness with Flight Results

    DTIC Science & Technology

    1944-01-01

    the wing-aileron system were obtained from drawings supplied by the Republic Aviation Corporation and are given in figure 1 and . table I. The... Aviation Corporation indicated that the elastic axis for the P-47C-1-RE wing was of the order of Sjy percent of the chord length back of the quarter...center from the aerodynamic center on the aerodynamic torque due to the rolling maneuver was neglected because data obtained from the Republic

  8. Effect of grain sizes on mechanical properties and biodegradation behavior of pure iron for cardiovascular stent application

    PubMed Central

    Obayi, Camillus Sunday; Tolouei, Ranna; Mostavan, Afghany; Paternoster, Carlo; Turgeon, Stephane; Okorie, Boniface Adeleh; Obikwelu, Daniel Oray; Mantovani, Diego

    2016-01-01

    Abstract Pure iron has been demonstrated as a potential candidate for biodegradable metal stents due to its appropriate biocompatibility, suitable mechanical properties and uniform biodegradation behavior. The competing parameters that control the safety and the performance of BMS include proper strength-ductility combination, biocompatibility along with matching rate of corrosion with healing rate of arteries. Being a micrometre-scale biomedical device, the mentioned variables have been found to be governed by the average grain size of the bulk material. Thermo-mechanical processing techniques of the cold rolling and annealing were used to grain-refine the pure iron. Pure Fe samples were unidirectionally cold rolled and then isochronally annealed at different temperatures with the intention of inducing different ranges of grain size. The effect of thermo-mechanical treatment on mechanical properties and corrosion rates of the samples were investigated, correspondingly. Mechanical properties of pure Fe samples improved significantly with decrease in grain size while the corrosion rate decreased marginally with decrease in the average grain sizes. These findings could lead to the optimization of the properties to attain an adequate biodegradation-strength-ductility balance. PMID:25482336

  9. Effect of grain sizes on mechanical properties and biodegradation behavior of pure iron for cardiovascular stent application.

    PubMed

    Obayi, Camillus Sunday; Tolouei, Ranna; Mostavan, Afghany; Paternoster, Carlo; Turgeon, Stephane; Okorie, Boniface Adeleh; Obikwelu, Daniel Oray; Mantovani, Diego

    2016-01-01

    Pure iron has been demonstrated as a potential candidate for biodegradable metal stents due to its appropriate biocompatibility, suitable mechanical properties and uniform biodegradation behavior. The competing parameters that control the safety and the performance of BMS include proper strength-ductility combination, biocompatibility along with matching rate of corrosion with healing rate of arteries. Being a micrometre-scale biomedical device, the mentioned variables have been found to be governed by the average grain size of the bulk material. Thermo-mechanical processing techniques of the cold rolling and annealing were used to grain-refine the pure iron. Pure Fe samples were unidirectionally cold rolled and then isochronally annealed at different temperatures with the intention of inducing different ranges of grain size. The effect of thermo-mechanical treatment on mechanical properties and corrosion rates of the samples were investigated, correspondingly. Mechanical properties of pure Fe samples improved significantly with decrease in grain size while the corrosion rate decreased marginally with decrease in the average grain sizes. These findings could lead to the optimization of the properties to attain an adequate biodegradation-strength-ductility balance.

  10. Effect of Work Group Size and Task Size on Observers' Job Characteristics Ratings.

    ERIC Educational Resources Information Center

    Greenberg, Carl I.; And Others

    The Job Characteristics Model proposed by Hackman and his associates postulates that positive personal and work outcomes are derived from five core job dimensions: skill variety, task identity, task significance, autonomy, and feedback from the job. The effects of the number of workers (work group size) and the number of tasks (task size) on…

  11. Can serving-size labels reduce the portion-size effect? A pilot study.

    PubMed

    Spanos, Samantha; Kenda, Andree S; Vartanian, Lenny R

    2015-01-01

    Research has shown that the bigger the portion that people are served, the more food they eat; this phenomenon is referred to as the portion-size effect. Providing objective serving-size information on food products has been shown to reduce the influence of external food cues on people's eating behavior. The current study examined whether providing objective serving-size information would also reduce the portion-size effect. 100 female participants were served either a small or large portion of pizza in the context of a taste test. The large portion was either unlabeled, labeled as "Contains 2 servings," or labeled as "Contains 4 servings." Food intake was lower when the large portion was labeled "Contains 4 servings" compared to when it was labeled "Contains 2 servings." Moreover, participants' intake in the large portion/4 servings condition was statistically similar to the intake of participants in the small portion condition. Thus, the standard portion-size effect was observed when the large portion was unlabeled or was labeled as "Contains 2 servings," but not when the large portion was labeled as "Contains 4 servings". These findings suggest that providing serving-size information can reduce the portion-size effect, but that the specific content (and not just the presence) of serving-size information is important in determining food intake. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Sample Size Calculations for Precise Interval Estimation of the Eta-Squared Effect Size

    ERIC Educational Resources Information Center

    Shieh, Gwowen

    2015-01-01

    Analysis of variance is one of the most frequently used statistical analyses in the behavioral, educational, and social sciences, and special attention has been paid to the selection and use of an appropriate effect size measure of association in analysis of variance. This article presents the sample size procedures for precise interval estimation…

  13. Sample Size Calculations for Precise Interval Estimation of the Eta-Squared Effect Size

    ERIC Educational Resources Information Center

    Shieh, Gwowen

    2015-01-01

    Analysis of variance is one of the most frequently used statistical analyses in the behavioral, educational, and social sciences, and special attention has been paid to the selection and use of an appropriate effect size measure of association in analysis of variance. This article presents the sample size procedures for precise interval estimation…

  14. Effect of Work Group Size and Task Size on Observers' Job Characteristics Ratings.

    ERIC Educational Resources Information Center

    Greenberg, Carl I.; And Others

    The Job Characteristics Model proposed by Hackman and his associates postulates that positive personal and work outcomes are derived from five core job dimensions: skill variety, task identity, task significance, autonomy, and feedback from the job. The effects of the number of workers (work group size) and the number of tasks (task size) on…

  15. Preventing the pack size effect: exploring the effectiveness of pictorial and non-pictorial serving size recommendations.

    PubMed

    Versluis, Iris; Papies, Esther K; Marchiori, David

    2015-04-01

    People eat more from large than from small packs, which is known as the pack size effect. We hypothesized that providing a serving size recommendation would reduce the influence of the pack size on consumption and would thus diminish the pack size effect. Moreover, we hypothesized that a pictorial serving size recommendation, displaying food amounts visually, would be more effective than a non-pictorial recommendation that communicates the recommended amount in grams only. We tested these hypotheses in two online experiments (N = 317 and N = 324) and in one lab experiment (N = 89). In the online experiments, participants were shown a small or a large pack of unhealthy snacks, with or without a serving size recommendation. The main outcome measure was expected consumption. Replicating the pack size effect in an online setting, we found that participants expected to consume more food from large than from small packs. Furthermore, the pack size effect was considerably stronger for men than for women. Importantly, when including portion size preferences as a covariate, the pictorial serving size recommendation significantly reduced expected consumption, especially when placed on a large pack, as hypothesized. The non-pictorial serving size recommendation had no effect. In the lab experiment, students received a large bag of M&M's which did or did not contain the pictorial serving size recommendation. We again included general portion size preferences as a covariate. The serving size recommendation significantly lowered the amount of M&M's that participants served themselves, but only when participants reported to have noticed the serving size recommendation. We conclude that providing a pictorial serving size recommendation can be an effective intervention strategy to reduce the pack size effect, if it attracts sufficient attention.

  16. Rolling into spatial disorientation: simulator demonstration of the post-roll (Gillingham) illusion.

    PubMed

    Nooij, Suzanne A E; Groen, Eric L

    2011-05-01

    Spatial disorientation (SD) is still a contributing factor in many aviation accidents, stressing the need for adequate SD training scenarios. In this article we focused on the post-roll effect (the sensation of rolling back after a roll maneuver, such as an entry of a coordinated turn) and investigated the effect of roll stimuli on the pilot's ability to stabilize their roll attitude. This resulted in a ground-based demonstration scenario for pilots. The experiments took place in the advanced 6-DOF Desdemona motion simulator, with the subject in a supine position. Roll motions were either fully automated with the subjects blindfolded (BLIND), automated with the subject viewing the cockpit interior (COCKPIT), or self-controlled (LEAD). After the roll stimulus subjects had to cancel all perceived simulator motion without any visual feedback. Both the roll velocity and duration were varied. In 68% of all trials subjects corrected for the perceived motion of rolling back by initiating a roll motion in the same direction as the preceeding roll. The effect was dependent on both rate and duration, in a manner consistent with semicircular canal dynamics. The effect was smallest in the BLIND scenario, but differences between simulation scenarios were non-significant. The results show that the effects of the post-roll illusion on aircraft control can be demonstrated adequately in a flight simulator using an attitude control task. The effect is present even after short roll movements, occurring frequently in flight. Therefore this demonstration is relevant for spatial disorientation training programs for pilots.

  17. Wheel squeal noise: A simplified model to simulate the effect of rolling speed and angle of attack

    NASA Astrophysics Data System (ADS)

    Liu, Xiaogang; Meehan, Paul A.

    2015-03-01

    The sound pressure level of wheel squeal has been shown to increase with angle of attack and rolling speed in both field and laboratory tests. However, the exact causes behind the manner of increase are still unknown. To investigate this, a simplified analytical vibration model in the time domain is integrated with nonlinear rolling contact theory developed for wheel squeal. This model is used to simulate the vibration velocity of a test rig wheel at different rolling speeds and angles of attack. The simulated vibration velocities correlate well in the trend with the recorded sound pressure levels of wheel squeal in laboratory tests. Lateral creepage and force at various angles of attack and rolling speeds in the rolling contact are simulated. It is found that due to the interaction of wheel vibration, lateral force and creepage, the vibration velocity amplitude of the wheel increases with angle of attack and rolling speed. The generation mechanism of wheel squeal is explained from the view of energy input per cycle of vibration. Furthermore, the reasons why the sound pressure levels of wheel squeal increase with rolling speed and angle of attack are investigated, and these phenomena are explained theoretically based on energy input and the nonlinear creep behaviour.

  18. An experimental study for determining human discomfort response to roll vibration

    NASA Technical Reports Server (NTRS)

    Leatherwood, J. D.; Dempsey, T. K.; Clevenson, S. A.

    1976-01-01

    An experimental study using a passenger ride quality apparatus (PRQA) was conducted to determine the subjective reactions of passengers to roll vibrations. The data obtained illustrate the effect upon human comfort of several roll-vibration parameters: namely, roll acceleration level, roll frequency, and seat location (i.e., distance from axis of rotation). Results of an analysis of variance indicated that seat location had no effect on discomfort ratings of roll vibrations. The effect of roll acceleration level was significant, and discomfort ratings increased markedly with increasing roll acceleration level at all roll frequencies investigated. Of particular interest, is the fact that the relationship between discomfort ratings and roll acceleration level was linear in nature. The effect of roll frequency also was significant as was the interaction between roll acceleration level and roll frequency.

  19. Regression models and effect size measures for single case designs.

    PubMed

    Swaminathan, Hariharan; Rogers, H Jane; Horner, Robert H; Sugai, George; Smolkowski, Keith

    2014-01-01

    A regression modelling approach for the analysis of single case designs (SCDs) is described in this paper. The approach presented addresses two key issues in the analysis of SCDs. The first issue is that of serial dependence among the observations in SCDs. The second issue is that of an effect size measure appropriate for SCDs. As with traditional between-subjects experimental designs, effect size measures are critical in assessing the impact of interventions in SCDs. Although effect size measures when there is level change without trend are straightforward to obtain and have been well studied, the situation is different when there are changes in both level and trend. An effect size measure that combines changes in levels and slopes and that is comparable to the d-type effect size measure obtained in between-subjects designs is presented. Finally, an inferential procedure for assessing the effect of the intervention based on the effect size measure is provided and illustrated.

  20. Effects of Ultra-Fast Cooling After Hot Rolling and Intercritical Treatment on Microstructure and Cryogenic Toughness of 3.5%Ni Steel

    NASA Astrophysics Data System (ADS)

    Wang, Meng; Liu, Zhenyu

    2017-07-01

    A novel process comprised of ultra-fast cooling after control rolling, intercritical quenching and tempering (UFC-LT) was applied to 3.5%Ni steel. In addition, quenching and tempering (QT) treatment was conducted in comparison. The present study focuses on the relationship between the microstructure and cryogenic toughness of 3.5%Ni steel. Results show that the microstructure of steel treated by UFC-LT consisted of tempered martensite, intercritical ferrite and two types of reversed austenite (RA) (needle shape and blocky). Compared to the QT sample, the UFC-LT sample's ultimate tensile strength decreased slightly, while its elongation increased from 32.3 to 35.7%, and its Charpy absorption energy at -135 °C increased from 112 to 237 J. The ductile-brittle transition temperature of UFC-LT sample was lower than that of the QT sample by 18 °C. The superior cryogenic toughness after UFC-LT compared to QT treatment can be attributed to the dissolution of cementite, approximately 3.0% increase in RA and the decrease in effective grain size.

  1. Effects of Ti and B Addition on Microstructures and Mechanical Properties of Hot-Rolled High-Strength Nb-Containing Steels

    NASA Astrophysics Data System (ADS)

    Meng, Xianna; Li, Cong; Chen, Wanglin

    2016-08-01

    Four microalloyed samples were designed to study the effects of Ti and B additions on microstructures and mechanical properties. Experimental results show that the samples without B addition mainly contain well-developed pearlite and polygonal ferrite, whereas the B-containing samples consist of degenerated pearlite, polygonal ferrite, and Widmanstätten ferrite (WF). The B addition promotes the precipitation of the complex (Ti,Al,Nb)N and (Ti,Al,Nb)2CS phases during the hot-rolling process. Grain sizes are significantly refined by the combinations of undissolved (Ti,Al)N, (Ti,Al,Nb)N complex, (Ti,Al,Nb)2CS, and fine inclusions, which act as the nucleation sites of intragranular ferrite. The core of complex (Ti,Al,Nb)N precipitate is undissolved Ti-N-rich (Ti,Al)N phase, and the cap is Nb-N-rich (Nb,Ti)N phase. The property measurements show that the B addition enhances comprehensive properties of tensile strength and elongation, but decreases fracture toughness due to higher contents of the WF and subgrains.

  2. Improvement of vehicle roll stability by varying suspension properties

    NASA Astrophysics Data System (ADS)

    Shim, Taehyun; Velusamy, Pradheep C.

    2011-02-01

    Vehicle roll dynamics are strongly influenced by suspension properties such as roll centre height, roll steer, and roll camber. In this paper, the effects of suspension properties on vehicle roll response have been investigated using a multi-body vehicle dynamics programme. Roll dynamics of a vehicle model with MacPherson (front) and multilink (rear) suspensions were evaluated for the fishhook manoeuvre and variations of its roll response due to changes in the suspension properties were assessed by quantitatively analysing the vehicle response through simulation. Critical suspension design parameters for vehicle roll dynamics were identified and adjusted to improve roll stability of the vehicle model with passive suspension. Design of experiments has been used for identifying critical hardpoints affecting the suspension parameters, and optimisation techniques were employed for parameter optimisation. This approach provides a viable alternative to costlier active control systems for economy-class vehicles.

  3. Hall-Petch effect: Another manifestation of size effect

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Dunstan, David; Bushby, Andy

    In the 1950s, Hall and Petch first established a quantitative relationship, expressed by the famous Hall-Petch equation: σd =σ0 +kHP/√{ d} There is a very large body of experimental data in the literature reinforcing this dependence in a very wide range of metals. Recently, we presented some of the classic data sets which have been considered to confirm the Hall-Petch equation and showed they are equally well consistent with the equation ɛel (d) =ɛ0 +kln/(d) d Eq. 2 is based on critical thickness theory. Fitting to Eq.1 with the exponent 0.5 replaced by the free fitting parameter x, the confidence interval for the exponent is 0.5 size of each study. The normalised kHP are widely scattered. However, the lower bound of the scatter shows a clear dependence on grain size. The Hall-Petch dependence of the strength on grain size, if it obeys Eq.2, is another manifestation of the size effect.

  4. Study of Titanium Alloy Sheet During H-sectioned Rolling Forming Using the Taguchi Method

    SciTech Connect

    Chen, D.-C.; Gu, W.-S.; Hwang, Y.-M.

    2007-05-17

    This study employs commercial DEFORM three-dimensional finite element code to investigate the plastic deformation behavior of Ti-6Al-4V titanium alloy sheet during the H-sectioned rolling process. The simulations are based on a rigid-plastic model and assume that the upper and lower rolls are rigid bodies and that the temperature rise induced during rolling is sufficiently small that it can be ignored. The effects of the roll profile, the friction factor between the rolls and the titanium alloy, the rolling temperature and the roll radii on the rolling force, the roll torque and the effective strain induced in the rolled product are examined. The Taguchi method is employed to optimize the H-sectioned rolling process parameters. The results confirm the effectiveness of this robust design methodology in optimizing the H-sectioned rolling process parameters for the current Ti-6Al-4V titanium alloy.

  5. Investigation and Modeling of Recrystallization of Cold Rolled Automotive Steels

    NASA Astrophysics Data System (ADS)

    Zhitelev, P.; Vasilyev, A.; Sokolov, S.; Sokolov, D.; Paligin, R.

    2016-04-01

    Ferrite recrystallization in cold-rolled sheets of automotive steels has been studied using a Geeble 3800 complex. Mathematical models for quantitative description of the process kinetics and prediction of the recrystallized ferrite grain size have been developed. These models enable performing calculations for any arbitrary heating regimes, including those that are used in industrial production practice, and allow taking into account the effects of a fairly wide range variation of the chemical composition of steels.

  6. Effects of service condition on rolling contact fatigue failure mechanism and lifetime of thermal spray coatings—A review

    NASA Astrophysics Data System (ADS)

    Cui, Huawei; Cui, Xiufang; Wang, Haidou; Xing, Zhiguo; Jin, Guo

    2015-01-01

    The service condition determines the Rolling Contact Fatigue(RCF) failure mechanism and lifetime under ascertain material structure integrity parameter of thermal spray coating. The available literature on the RCF testing of thermal spray coatings under various condition services is considerable; it is generally difficult to synthesize all of the result to obtain a comprehensive understanding of the parameters which has a great effect on a thermal spray coating's resistance of RCF. The effects of service conditions(lubrication states, contact stresses, revolve speed, and slip ratio) on the changing of thermal spray coatings' contact fatigue lifetime is introduced systematically. The effects of different service condition on RCF failure mechanism of thermal spray coating from the change of material structure integrity are also summarized. Moreover, In order to enhance the RCF performance, the parameter optimal design formula of service condition and material structure integrity is proposed based on the effect of service condition on thermal spray coatings' contact fatigue lifetime and RCF failure mechanism. The shortage of available literature and the forecast focus in future researches are discussed based on available research. The explicit result of RCF lifetime law and parameter optimal design formula in term of lubrication states, contact stresses, revolve speed, and slip ratio, is significant to improve the RCF performance on the engineering application.

  7. Pressure versus drag effects on crater size

    NASA Astrophysics Data System (ADS)

    Schmidt, R. M.

    1993-03-01

    The topic of atmospheric effects on crater formation is very complex because it includes not only pressure effects on excavation, but also drag effects on ejecta placement. Experiments have to be designed very carefully to allow isolation of the two phenomena. Historically, numerous investigators have shown an influence of atmospheric pressure. However, none have identified the scaling that correctly isolates pressure from drag effects. On-going work in explosive cratering has produced scaling paradigms for deeply buried explosive charges where drag effects are negligible. Here it was found that increased pressure caused significant induced strength effects that impeded crater excavation. The effect is more pronounced with increasing burial depth and less pronounced with increased yield.

  8. Size effects of pore density and solute size on water osmosis through nanoporous membrane.

    PubMed

    Zhao, Kuiwen; Wu, Huiying

    2012-11-15

    Understanding the behavior of osmotic transport across nanoporous membranes at molecular level is critical to their design and applications, and it is also beneficial to the comprehension of the mechanism of biological transmembrane transport processes. Pore density is an important parameter for nanoporous membranes. To better understand the influence of pore density on osmotic transport, we have performed systematic molecular dynamics simulations on water osmosis across nanoporous membranes with different pore densities (i.e., number of pores per unit area of membrane). The simulation results reveal that significant size effects occur when the pore density is so high that the center-to-center distance between neighboring nanopores is comparable to the solute size. The size effects are independent of the pore diameter and solute concentration. A simple quantitative correlation between pore density, solute size, and osmotic flux has been established. The results are excellently consistent with the theoretical predictions. It is also shown that solute hydration plays an important role in real osmotic processes. Solute hydration strengthens the size effects of pore density on osmotic processes due to the enlarged effective solute size induced by hydration. The influence of pore density, solute size, and solute hydration on water osmosis through nanoporous membranes can be introduced to eliminate the deviations of real osmotic processes from ideal behavior.

  9. Effective population size and genetic conservation criteria for bull trout

    Treesearch

    Bruce E. Rieman; F. W. Allendorf

    2001-01-01

    Effective population size (Ne) is an important concept in the management of threatened species like bull trout Salvelinus confluentus. General guidelines suggest that effective population sizes of 50 or 500 are essential to minimize inbreeding effects or maintain adaptive genetic variation, respectively....

  10. Effect of hot band grain size on development of textures and magnetic properties in 2.0% Si non-oriented electrical steel sheet

    NASA Astrophysics Data System (ADS)

    Lee, K. M.; Huh, M. Y.; Lee, H. J.; Park, J. T.; Kim, J. S.; Shin, E. J.; Engler, O.

    2015-12-01

    The effect of hot band grain size on the development of crystallographic texture and magnetic properties in non-oriented electrical steel sheet was studied. After cold rolling the samples with different initial grain sizes displayed different microstructures and micro-textures but nearly identical macro-textures. The homogeneous recrystallized microstructure and micro-texture in the sample having small grains caused normal continuous grain growth. The quite irregular microstructure and micro-texture in the recrystallized sample with large initial grain size provided a preferential growth of grains in <001>//ND and <113>//ND which were beneficial for developing superior magnetic properties.

  11. Resistance to Rolling in the Adhesive Contact of Two Elastic Spheres

    NASA Technical Reports Server (NTRS)

    Dominik, C.; Tielens, A. G. G. M.

    1995-01-01

    For the stability of agglomerates of micron sized particles it is of considerable importance to study the effects of tangential forces on the contact of two particles. If the particles can slide or roll easily over each other, fractal structures of these agglomerates will not be stable. We use the description of contact forces by Johnson, Kendall and Roberts, along with arguments based on the atomic structure of the surfaces in contact, in order to calculate the resistance to rolling in such a contact. It is shown that the contact reacts elastically to torque forces up to a critical bending angle. Beyond that, irreversible rolling occurs. In the elastic regime, the moment opposing the attempt to roll is proportional to the bending angle and to the pull-off force P(sub c). Young's modulus of the involved materials has hardly any influence on the results. We show that agglomerates of sub-micron sized particles will in general be quite rigid and even long chains of particles cannot be bent easily. For very small particles, the contact will rather break than allow for rolling. We further discuss dynamic properties such as the possibility of vibrations in this degree of freedom and the typical amount of rolling during a collision of two particles.

  12. Effect of Artificial Pitch Damping on the Longitudinal and Rolling Stability of Aircraft with Negative Static Margins

    NASA Technical Reports Server (NTRS)

    Moul, Martin T.; Brown, Lawrence W.

    1959-01-01

    A preliminary theoretical investigation has been made of the short-period longitudinal and steady-rolling (inertia coupling) stability of a hypersonic glider configuration for center-of-gravity locations rear-ward of the airplane neutral point. Such center-of-gravity positions for subsonic flight would improve performance by reducing supersonic and hypersonic static margins and trim drag. Results are presented of stability calculations and a simulator study for a velocity of 700 ft/sec and an altitude of 401,000 feet. With no augmentation, the airplane was rapidly divergent and was considered unsatisfactory in the simulator study. When a pitch damper was employed as a stability augmenter, the short-period mode became overdamped, and the airplane was easily controlled on the simulator. A steady-rolling analysis showed that the airplane can be made free of rolling divergence for all roll rates with an appropriate damper gain.

  13. Density-dependent effects on growth, body size, and clutch size in Black Brant

    USGS Publications Warehouse

    Sedinger, James S.; Lindberg, Mark S.; Person, Brian T.; Eichholz, Michael W.; Herzog, Mark P.; Flint, Paul L.

    1998-01-01

    We documented gosling size in late summer, adult body size, and clutch size of known-age Black Brant (Branta bernicla nigricans) females nesting on the Tutakoke River colony between 1986 and 1995. During this period, the colony increased from 1,100 to >5,000 nesting pairs. Gosling mass at 30 days of age declined from 764 ± SE of 13 g and 723 ± 15 g for males and females, respectively, in the 1986 cohort, to 665 ± 18 g and 579 ± 18 g in the 1994 cohort. Gosling size was directly negatively correlated with number of Black Brant broods. We detected no trend in adult body size for individuals from these cohorts; in fact, adults from the 1992 and 1994 cohorts had the largest overall masses. Clutch size increased with age from 3.4 eggs for 2-year-old females to 4.4 eggs for 5-year-old females. Clutch size declined during the study by 0.20 (3-year-old females) to 0.45 (2-year-old females) eggs. Clutch size did not decline between the 1986 and 1990 cohorts for females that were >5 years old. Our results for clutch size and gosling size are similar to those recorded for Lesser Snow Geese (Chen caerulescens caerulescens). Our failure to detect a trend in adult body size, however, differs from the response of other geese to increasing population density. We interpret this difference in effects of density on adult size between Black Brant and other geese as an indication of stronger selection against the smallest individuals in Black Brant relative to other species of geese.

  14. Effects of MC-Type Carbide Forming and Graphitizing Elements on Thermal Fatigue Behavior of Indefinite Chilled Cast Iron Rolls

    NASA Astrophysics Data System (ADS)

    Ahiale, Godwin Kwame; Choi, Won-Doo; Suh, Yongchan; Lee, Young-Kook; Oh, Yong-Jun

    2015-11-01

    The thermal fatigue behavior of indefinite chilled cast iron rolls with various V+Nb contents and Si/Cr ratios was evaluated. Increasing the ratio of Si/Cr prolonged the life of the rolls by reducing brittle cementites. Higher V+Nb addition also increased the life through the formation of carbides that refined and toughened the martensite matrix and reduced the thermal expansion mismatch in the microstructure.

  15. How Consistent Are Class Size Effects?

    ERIC Educational Resources Information Center

    Konstantopoulos, Spyros

    2011-01-01

    Thus far researchers have focused on computing average differences in student achievement between smaller and larger classes. In this study, the author focus on the distribution of the small class effects at the school level and compute the inconsistency of the small class effects across schools. The author use data from Project STAR to estimate…

  16. Effect of cold rolling on fatigue crack propagation of TiNi/Al6061 shape memory composite

    NASA Astrophysics Data System (ADS)

    Park, Young Chul; Kang, Jung Ho; Lee, Jin Kyung; Lee, Gyu Chang; Furuya, Yasybumi

    2007-08-01

    A TiNi alloy fiber was used to recover the original shape of materials using its shape memory effect. The shape memory alloy plays an important role within the metal matrix composite. The shape memory alloy can control the crack propagation in the metal matrix composite, and improve the tensile strength of the composite. In this study, TiNi/Al6061 shape memory alloy (SMA) composite was fabricated by the hot press method, and pressed by a roller for its strength improvement. The four kinds of specimens were fabricated with 0%, 3.2%, 5.2% and 7% volume fraction of TiNi alloy fiber, respectively. A fatigue test has been performed to evaluate the crack initiation and propagation for the TiNi/Al6061 SMA composite fabricated by this method. In order to study the shape memory effect of the TiNi alloy fiber, the test has also been done under both room temperature and high temperature conditions. The relationship between the crack growth rate and the stress intensity factor was clarified for the composite, and the cold rolling effect was also studied.

  17. Effect of Annealing on Mechanical Properties and Formability of Cold Rolled Thin Sheets of Fe-P P/M Alloys

    NASA Astrophysics Data System (ADS)

    Trivedi, Shefali; Ravi Kumar, D.; Aravindan, S.

    2016-10-01

    Phosphorus in steel is known to increase strength and hardness and decrease ductility. Higher phosphorus content (more than 0.05%), however, promotes brittle behavior due to segregation of Fe3P along the grain boundaries which makes further mechanical working of these alloys difficult. In this work, thin sheets of Fe-P alloys (with phosphorus in range of 0.1-0.35%) have been developed through processing by powder metallurgy followed by hot rolling and cold rolling. The effect of phosphorus content and annealing parameters (temperature and time) on microstructure, mechanical properties, formability in biaxial stretching and fracture behavior of the cold rolled and annealed sheets has been studied. A comparison has also been made between the properties of the sheets made through P/M route and the conventional cast route with similar phosphorus content. It has been shown that thin sheets of Fe-P alloys with phosphorous up to 0.35% possessing a good combination of strength and formability can be produced through rolling of billets of these alloys made through powder metallurgy technique without the problem of segregation.

  18. How consistent are class size effects?

    PubMed

    Konstantopoulos, Spyros

    2011-02-01

    Thus far researchers have focused on computing average differences in student achievement between smaller and larger classes. In this study, the author focus on the distribution of the small class effects at the school level and compute the inconsistency of the small class effects across schools. The author use data from Project STAR to estimate small class effects for each school on mathematics and reading scores from kindergarten through third grade. Then, all school estimates were combined to calculate an overall weighted average. The results revealed that a large proportion of the school-specific small class effects are positive, while a smaller proportion of the estimates are negative. Although students benefit considerably from being in small classes in many schools, in other schools being in small classes is either not beneficial or is a disadvantage. Small class effects were inconsistent and varied significantly across schools in all grades indicating a small class by school interaction.

  19. Numerical analysis of Swiss roll metamaterials.

    PubMed

    Demetriadou, A; Pendry, J B

    2009-08-12

    A Swiss roll metamaterial is a resonant magnetic medium, with a negative magnetic permeability for a range of frequencies, due to its self-inductance and self-capacitance components. In this paper, we discuss the band structure, S-parameters and effective electromagnetic parameters of Swiss roll metamaterials, with both analytical and numerical results, which show an exceptional convergence.

  20. Portion size and intended consumption. Evidence for a pre-consumption portion size effect in males?

    PubMed

    Robinson, Eric; te Raa, Wesselien; Hardman, Charlotte A

    2015-08-01

    Larger portions increase energy intake (the 'portion size effect'); however, the mechanisms behind this effect are unclear. Although pre-meal intentions are thought to be an important determinant of energy intake, little research has examined how much of a meal individuals intend to eat when served standard versus larger portion sizes. Three studies examined the effect of manipulating portion size on intended food consumption. In Studies 1 (spaghetti bolognese) and 2 (curry and rice) male participants were shown an image of either a standard or a larger meal and indicated how much of the meal they intended to consume. In Study 3 male and female participants were served either a standard or a larger portion of ice cream for dessert, they indicated how much they intended to consume and then ate as much of the ice cream as they desired. Regardless of being shown standard or large portion sizes, in Studies 1 and 2 participants reported that they intended to eat the majority of the meal, equating to a large difference in intended energy consumption between portion size conditions (a 'pre-consumption portion size effect'). This finding was replicated in male participants in Study 3, although females intended to eat a smaller proportion of the larger portion of ice cream, compared to the standard portion. Both male and female participants tended to eat in accordance with their pre-meal intentions and a portion size effect on actual consumption was subsequently observed in males, but not in females. The portion size effect may be observed when measuring pre-meal intended consumption in males. Copyright © 2015. Published by Elsevier Ltd.

  1. Effects of user's actions on rolling resistance and wheelchair stability during handrim wheelchair propulsion in the field.

    PubMed

    Sauret, Christophe; Vaslin, Philippe; Lavaste, François; de Saint Remy, Nicolas; Cid, Mariano

    2013-03-01

    Currently, rolling resistance and wheelchair stability during manual wheelchair propulsion can be assessed from the loads applied on the front and rear wheels, which are determined in a static condition. However, a user's actions on the wheelchair would change these loads during locomotion, which should affect both the rolling resistance and wheelchair stability. The goal of this study was to verify these assumptions and assess how much the rolling resistance and wheelchair stability are affected by the user's actions during propulsion. For that purpose, a mechanical model was developed using measurements of an instrumented wheelchair equipped with several six-component dynamometers. Experiments were performed by three subjects propelling the instrumented wheelchair over flat ground. The results showed variations over wide ranges of the fore-aft distribution of the total load, rolling resistance, wheelchair stability, wheelchair velocity and mechanical power dissipated by the rolling resistance during the propulsion cycle. In addition, the time courses of all these variables differed with the subject. Finally, this study demonstrated the possibility of assessing intra-cycle values of both rolling resistance and wheelchair stability during manual wheelchair displacements in the field, which provides a technical step towards evaluating a wheelchair user in his daily environment. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

  2. Texture evolution in warm rolled low-carbon steels

    NASA Astrophysics Data System (ADS)

    Sanchez Araiza, Miguel

    The effect of warm and cold rolling parameters on the development of annealing textures and their effects on the final formability were studied in two LC steels containing 0.8%Cr. Warm rolling temperatures between 640 and 750°C were employed, together with reductions of 65% to 80%. The effects of an additional cold rolling reduction of 40%, different initial hot band grain sizes (HBGSs) and a decrease in the heating rate during annealing were also studied. The ND fibre, <111>//ND, of the recrystallization texture was strengthened as the warm rolling temperature was decreased. A noticeable improvement in both the continuity and intensity of the ND fibre was obtained when samples were submitted to an additional 40% cold rolling reduction. The ND fibre was even more continuous and intense when a low heating rate was utilized, yielding r-values of 1.2 and 1.3 for the warm rolled and warm plus cold rolled samples, respectively. On the other hand, the volume fraction of grains containing shear bands is slightly lower for the finer HBGS. However, this does not reduce the amount of in-grain nucleation of gamma grains, suggesting that shear bands are not the only factor that has to be considered in the improvement of warm rolling textures. Although the normal anisotropy is not affected by the HBGS, much lower Deltar values were associated with the finer grained steel. The texture changes taking place during recrystallization were examined using electron back-scattered diffraction. The recrystallization textures resemble the deformation textures but with a more extensive alpha fibre that includes the {113}<471> orientation; the gamma fibre extends to the {554}<225>. These two orientations are related to the {112}<110> deformed grains by near 26° rotations about selected <110> axes. Nevertheless, both orientations appear in the early stages of recrystallization, an observation that does not support the oriented growth theory. The {111} < hkl> orientations are the first to

  3. Effect of steam-flaked or steam-rolled corn with or without Aspergillus oryzae in the diet on performance of dairy cows fed during hot weather.

    PubMed

    Yu, P; Huber, J T; Theurer, C B; Chen, K H; Nussio, L G; Wu, Z

    1997-12-01

    The objective of this study was to determine the effects of steam-rolled versus steam-flaked corn in the diet with or without the addition of a culture of Aspergillus oryzae on the performance of high producing dairy cows during hot summer weather. Thirty-two Holstein cows averaging 92 (+/- 60) d in milk were fed a pretreatment diet for 21 d followed by a 70-d experimental period in a completely randomized block design with a 2 x 2 factorial arrangement of treatments. Diets were 1) steam-flaked corn plus 3 g/d of A. oryzae, 2) steam-flaked corn, 3) steam-rolled corn plus 3 g/d of A. oryzae, and 4) steam-rolled corn. Intake was not affected significantly by grain processing or addition of A. oryzae. Compared with effects from steam-rolled corn in the diet, steam-flaked corn increased milk production; percentage of milk protein; yields of milk protein, lactose, and SNF; and the efficiency of conversion of dry matter to fat-corrected milk. Addition of A. oryzae tended to increase protein percentage and increased the percentage of SNF. Changes in body weight and body condition score tended to be higher, and somatic cell count tended to be lower, for cows fed the flaked corn than for cows fed the rolled corn. No interactions were significant. Treatments did not affect rectal temperatures or respiration rates; however, high mean values measured at 1400 h once weekly indicated thermal stress. These data show improved milk production from cows fed steam-flaked corn but not from those fed diets supplemented with A. oryzae.

  4. Nanogrid rolling circle DNA sequencing

    DOEpatents

    Church, George M.; Porreca, Gregory J.; Shendure, Jay; Rosenbaum, Abraham Meir

    2017-04-18

    The present invention relates to methods for sequencing a polynucleotide immobilized on an array having a plurality of specific regions each having a defined diameter size, including synthesizing a concatemer of a polynucleotide by rolling circle amplification, wherein the concatemer has a cross-sectional diameter greater than the diameter of a specific region, immobilizing the concatemer to the specific region to make an immobilized concatemer, and sequencing the immobilized concatemer.

  5. Effects of particle size distribution in thick film conductors

    NASA Technical Reports Server (NTRS)

    Vest, R. W.

    1983-01-01

    Studies of particle size distribution in thick film conductors are discussed. The distribution of particle sizes does have an effect on fired film density but the effect is not always positive. A proper distribution of sizes is necessary, and while the theoretical models can serve as guides to selecting this proper distribution, improved densities can be achieved by empirical variations from the predictions of the models.

  6. Two measures of effective population size for graphs.

    PubMed

    Broom, Mark; Voelkl, Bernhard

    2012-05-01

    Effective population size is a key parameter in population ecology because it allows prediction of the dynamics of genetic variation and the rate of genetic drift and inbreeding. It is important for the definition of "nearly neutral" mutations and, hence, has consequences for the fixation or extinction probabilities of advantageous and deleterious mutations. As graph-based population models become increasingly popular for studying evolution in spatially or socially structured populations, a neutral theory for evolution on graphs is called for. Here, we derive formulae for two alternative measures of effective population size, the variance effective and inbreeding effective size of general unweighted and undirected graphs. We show how these two quantities relate to each other and we derive effective sizes for the complete graph the cycle and bipartite graphs. For one-dimensional lattices and small-world graphs, we estimate the inbreeding effective size using simulations. The presented method is suitable for any structured population of haploid individuals with overlapping generations.

  7. Family size and effective population size in a hatchery stock of coho salmon (Oncorhynchus kisutch)

    USGS Publications Warehouse

    Simon, R.C.; McIntyre, J.D.; Hemmingsen, A.R.

    1986-01-01

    Means and variances of family size measured in five year-classes of wire-tagged coho salmon (Oncorhynchus kisutch) were linearly related. Population effective size was calculated by using estimated means and variances of family size in a 25-yr data set. Although numbers of age 3 adults returning to the hatchery appeared to be large enough to avoid inbreeding problems (the 25-yr mean exceeded 4500), the numbers actually contributing to the hatchery production may be too low. Several strategies are proposed to correct the problem perceived. Argument is given to support the contention that the problem of effective size is fairly general and is not confined to the present study population.

  8. Grain size effects on stability of nonlinear vibration with nanocrystalline NiTi shape memory alloy

    NASA Astrophysics Data System (ADS)

    Xia, Minglu; Sun, Qingping

    2017-10-01

    Grain size effects on stability of thermomechanical responses for a nonlinear torsional vibration system with nanocrystalline superelastic NiTi bar are investigated in the frequency and amplitude domains. NiTi bars with average grain size from 10 nm to 100 nm are fabricated through cold-rolling and subsequent annealing. Thermomechanical responses of the NiTi bar as a softening nonlinear damping spring in the torsional vibration system are obtained by synchronised acquisition of rotational angle and temperature under external sinusoidal excitation. It is shown that nonlinearity and damping capacity of the NiTi bar decrease as average grain size of the material is reduced below 100 nm. Therefore jump phenomena of thermomechanical responses become less significant or even vanish and the vibration system becomes more stable. The work in this paper provides a solid experimental base for manipulating the undesired jump phenomena of thermomechanical responses and stabilising the mechanical vibration system through grain refinement of NiTi SMA.

  9. Effects of wheel and hand-rim size on submaximal propulsion in wheelchair athletes.

    PubMed

    Mason, Barry S; Van Der Woude, Lucas H V; Tolfrey, Keith; Lenton, John P; Goosey-Tolfrey, Victoria L

    2012-01-01

    This study aimed to investigate the effects of fixed gear ratio wheel sizes on the physiological and biomechanical responses to submaximal wheelchair propulsion. Highly trained wheelchair basketball players (N = 13) propelled an adjustable sports wheelchair in three different wheel sizes (24, 25, and 26 inches) on a motor-driven treadmill. Each wheel was equipped with force-sensing hand-rims (SMARTWheel), which collected kinetic and temporal data. Oxygen uptake (V˙O2) and HR responses were measured with high-speed video footage collected to determine three-dimensional upper body joint kinematics. Mean power output and work per cycle decreased progressively with increasing wheel size (P < 0.0005). Increasing wheel size also reduced the physiological demand with reductions in VO2 for 25-inch (0.90 ± 0.20 L · min(-1), P = 0.01) and 26-inch wheels (0.87 ± 0.16 L · min(-1), P = 0.001) compared with 24-inch wheels (0.98 ± 0.20 L · min(-1)). In addition, reductions in HR were observed for 26-inch wheels (99 ± 6 beats · min(-1)) compared with 25-inch (103 ± 8 beats · min(-1), P = 0.018) and 24-inch wheels (105 ± 9 beats · min(-1), P = 0.004). Mean resultant forces also decreased progressively with increasing wheel size (P < 0.0005). However, no changes in temporal or upper body joint kinematics existed between wheel sizes. A greater power requirement owing to a greater rolling resistance in 24-inch wheels increased the physiological demand and magnitude of force application during submaximal wheelchair propulsion.

  10. Nuclear size effects in vibrational spectra.

    PubMed

    Almoukhalalati, Adel; Shee, Avijit; Saue, Trond

    2016-06-01

    We present a theoretical study of nuclear volume in the rovibrational spectra of diatomic molecules which is an extension of a previous study restricted to rotational spectra [Chem. Phys., 2012, 401, 103]. We provide a new derivation for the electron-nucleus electrostatic interaction energy which is basically independent of the choice of model for the nuclear charge distribution. Starting from this expression we derive expressions for the electronic, rotational and vibrational field shift parameters in terms of effective electron density and its first and second derivatives with respect to internuclear distance. The effective density is often approximated by the contact density, but we demonstrate that this leads to errors on the order of 10% and is furthermore not necessary since the contact and effective densities can be obtained at the same computational cost. We calculate the field shift parameters at the 4-component relativistic coupled-cluster singles-and-doubles level and find that our results confirm the experimental findings of Tiemann and co-workers [Chem. Phys., 1982, 68(21), 1982, Ber. Bunsenges. Phys. Chem., 1982, 86, 821], whereas we find no theoretical justification for a scaling factor introduced in later work [Chem. Phys., 1985, 93, 349]. For lead sulfide we study the effective density as a function of internuclear distance and find a minimum some 0.2 Å inside the equilibrium bond distance. We also discuss Bigeleisen-Goeppert-Mayer theory of isotope fractionation in light of our results.

  11. Effect of proving time on the quality of frozen pre-baked French style rolls elaborated with the addition of wholegrain flour and enzymes.

    PubMed

    Almeida, Eveline Lopes; Chang, Yoon Kil

    2014-11-01

    Proving is a step in the breadmaking process that can be crucial in determining the final characteristics of the product presented to the consumer. The objective of this work was to evaluate the effect of proving time on the quality of frozen pre-baked French style rolls elaborated with the addition of wholegrain flour and enzymes. With this objective, doughs from six different formulations were allowed to ferment to different stages of proving. The first stage corresponded to the stage where the dough presented the maximum point of volume development without losing its resistance to touch. The second stage was soon after the first one, being characterized by a loss of resistance to touch but without a marked loss of volume. The rolls were evaluated for their specific volume, crumb texture (firmness and springiness), oven spring, shape, cut opening and cut height. The results showed that the proving time influenced various characteristics of the pre-baked French bread. A longer proving time tended to result in greater specific volume of the rolls with greater crumb springiness, but with a less firm crumb and reduced cut opening and cut height. The oven spring and shape were not altered by the proving time. The increase in volume was the result of increases in the width and length of the rolls. This study showed that the proving time was one of the factors responsible for the collapse in the structure of the pre-baked rolls, and that an adequate formulation could overcome the loss in cut opening and cut height resulting from a longer proving time.

  12. Effect of Starting Microstructure on the Grain Refinement in Cold-Rolled Low-Carbon Steel During Annealing at Two Different Heating Rates

    NASA Astrophysics Data System (ADS)

    Karmakar, Anish; Mandal, Madhumanti; Mandal, Abhisek; Basiruddin Sk, Md.; Mukherjee, Subrata; Chakrabarti, Debalay

    2016-01-01

    Cold-rolled samples of different starting microstructures, namely ferrite-pearlite (F+P) and ferrite-martensite structures, with blocky martensite (F+Mb) and fibrous martensite (F+Mf) morphologies were reheated at two different heating rates (1 and 300 K/s) to sub-critical and inter-critical annealing temperatures [773 K to 1173 K (500 °C to 900 °C)] and immediately water quenched. Grain refinement after annealing of cold-rolled samples depends on the rate of recovery, recrystallization, transformation, and grain growth. Rapid recrystallization during annealing weakened the recrystallization-transformation interaction in F+P sample. Higher rate of ferrite recovery reduced the driving force for recrystallization, which weakened the recrystallization-transformation interaction during annealing of F+Mb sample. As a result, coarser grain structures were obtained after annealing of cold-rolled F+P and F+Mb starting structures. Strong recrystallization-transformation interaction and suppression of grain growth by uniformly distributed carbide particles and austenite islands (after transformation) offered finest ferrite grain size and best combination of strength and ductility in F+Mf sample.

  13. Reporting Effect Size Estimates in School Psychology Research

    ERIC Educational Resources Information Center

    Volker, Martin A.

    2006-01-01

    This article reviews the arguments for reporting effect size estimates as part of the statistical results in empirical studies. Following this review, formulas are presented for the calculation of major mean-difference and association-based effect size measures for t tests, one-way ANOVA, zero order correlation, simple regression, multiple…

  14. An Effect Size for Regression Predictors in Meta-Analysis

    ERIC Educational Resources Information Center

    Aloe, Ariel M.; Becker, Betsy Jane

    2012-01-01

    A new effect size representing the predictive power of an independent variable from a multiple regression model is presented. The index, denoted as r[subscript sp], is the semipartial correlation of the predictor with the outcome of interest. This effect size can be computed when multiple predictor variables are included in the regression model…

  15. Size Effect of Embedded Nanocrystals in Floating Gate MOSFET Devices

    NASA Astrophysics Data System (ADS)

    Cheng, X. Z.; Jalil, M. B. A.; Samudra, G. S.

    2011-12-01

    We investigate the transport and retention properties of a floating-gate MOSFET memory device incorporating embedded nanocrystals. Of particular interest is the nanocrystal size effect on the retention lifetime of the device. The quantum confinement effects and changes to the electrostatic energy arising from the decrease of the nanocrystal size are analyzed both numerically and analytically.

  16. Size effect of nano scale phase change random access memory.

    PubMed

    Son, Ji Hoon; Choi, HongKyw; Jang, Nakwon; Kim, Hong Seung; Yi, Dong Young; Lee, Seong Hwan

    2010-05-01

    In this paper, we have investigated the size effect of nano scale PRAM using three-dimensional finite element analysis tool. The reset current and temperature profile of PRAM cells with top and bottom electrode contact hole size were calculated by the numerical method. And temperature profile of PRAM unit cell with size and thickness of GST thin film was simulated. As top electrode contact size was smaller, reset current decreased. But these variations couldn't affect to operate memory. On the other hand, as bottom electrode contact size was smaller, reset current abruptly decreased.

  17. Roll Casting of Aluminum Alloy Clad Strip

    SciTech Connect

    Nakamura, R.; Tsuge, H.; Haga, T.; Watari, H.; Kumai, S.

    2011-01-17

    Casting of aluminum alloy three layers of clad strip was tried using the two sets of twin roll casters, and effects of the casting parameters on the cladding conditions were investigated. One twin roll caster was mounted on the other twin roll caster. Base strip was 8079 aluminum alloy and overlay strips were 6022 aluminum alloy. Effects of roll-load of upper and lower casters and melt temperature of the lower caster were investigated. When the roll-load of the upper and lower caster was large enough, the overlay strip could be solidified and be connected. The overlay strip could be connected when the melt of the overlay strip cast by the lower caster was low enough. Sound three layers of clad strip could be cast by proper conditions.

  18. A Demonstration Project in New York and Virginia: Retrofitting Cost-Effective Roll-over Protective Structures (CROPS) on Tractors.

    PubMed

    Hard, D L; McKenzie, E A; Cantis, D; May, J; Sorensen, J; Bayes, B; Madden, E; Wyckoff, S; Stone, B; Maass, J

    2015-07-01

    The NIOSH cost-effective roll-over protective structure (CROPS) demonstration project sought to determine whether three prototype roll-over protective structures (ROPS) designed to be retrofitted on Ford 8N, Ford 3000, Ford 4000, and Massey Ferguson 135 tractors could be installed in the field and whether they would be acceptable by the intended end users (farmers). There were a total of 50 CROPS. demonstrators (25 in New York and 25 in Virginia), with 45 observers attending the New York CROPS demonstrations and 36 observers attending the Virginia CROPS demonstrations, for a total of 70 participants in New York and 61 in Virginia. The oldest retrofitted tractors were 77 to 62 years old, while the newest retrofitted tractors were 40 to 37 years old. The most frequently retrofitted tractor in the CROPS demonstration project was a Ford 3000 series tractor (n = 19; 38%), followed by Ford 4000 (n = 11; 22%), Massey Ferguson 135 (n = 11; 22%), and Ford 8N (n = 9; 18%). A major issue of CROPS retrofitting was the rear wheel fenders. The effort involved in disassembling the fenders (removing the old bolts was often faster by cutting them with a torch), modifying the fender mounting brackets, and then reinstalling the fenders with the CROPS generally required the most time. In addition, various other semi-permanent equipment attachments, such as front-end loaders, required additional time and effort to fit with the CROPS. Demonstrators were asked to rank the reasons why they had not retrofitted their tractors with ROPS until they had enrolled in the CROPS demonstration program. ROPS "cost too much" was ranked as the primary reason for participants in both states (80% for New York and 88% for Virginia). The second highest ranked reasons were "ROPS wasn't available" for Virginia (80%) and "hassle to find ROPS" for New York (69%). The third highest ranked reasons were "not enough time to find ROPS" for New York (67%) and "hassle to find ROPS" for Virginia (79%). All

  19. A Demonstration Project in New York and Virginia: Retrofitting Cost-Effective Roll-over Protective Structures (CROPS) on Tractors

    PubMed Central

    Hard, David L.; McKenzie, E. A.; Cantis, Douglas; May, John; Sorensen, Julie; Bayes, Barbara; Madden, Erin; Wyckoff, Sherry; Stone, Bruce; Maass, Jimmy

    2015-01-01

    The NIOSH cost-effective roll-over protective structure (CROPS) demonstration project sought to determine whether three prototype roll-over protective structures (ROPS) designed to be retrofitted on Ford 8N, Ford 3000, Ford 4000, and Massey Ferguson 135 tractors could be installed in the field and whether they would be acceptable by the intended end users (farmers). There were a total of 50 CROPS demonstrators (25 in New York and 25 in Virginia), with 45 observers attending the New York CROPS demonstrations and 36 observers attending the Virginia CROPS demonstrations, for a total of 70 participants in New York and 61 in Virginia. The oldest retrofitted tractors were 77 to 62 years old, while the newest retrofitted tractors were 40 to 37 years old. The most frequently retrofitted tractor in the CROPS demonstration project was a Ford 3000 series tractor (n = 19; 38%), followed by Ford 4000 (n = 11; 22%), Massey Ferguson 135 (n = 11; 22%), and Ford 8N (n = 9; 18%). A major issue of CROPS retrofitting was the rear wheel fenders. The effort involved in disassembling the fenders (removing the old bolts was often faster by cutting them with a torch), modifying the fender mounting brackets, and then reinstalling the fenders with the CROPS generally required the most time. In addition, various other semi-permanent equipment attachments, such as front-end loaders, required additional time and effort to fit with the CROPS. Demonstrators were asked to rank the reasons why they had not retrofitted their tractors with ROPS until they had enrolled in the CROPS demonstration program. ROPS “cost too much” was ranked as the primary reason for participants in both states (80% for New York and 88% for Virginia). The second highest ranked reasons were “ROPS wasn’t available” for Virginia (80%) and “hassle to find ROPS” for New York (69%). The third highest ranked reasons were “not enough time to find ROPS” for New York (67%) and “hassle to find ROPS” for Virginia

  20. Effect size calculations for the clinician: methods and comparability.

    PubMed

    Seidel, Jason A; Miller, Scott D; Chow, Daryl L

    2014-01-01

    The measurement of clinical change via single-group pre-post effect size has become increasingly common in psychotherapy settings that collect practice-based evidence and engage in feedback-informed treatment. Different methods of calculating effect size for the same sample of clients and the same measure can lead to wide-ranging results, reducing interpretability. Effect sizes from therapists-including those drawn from a large web-based database of practicing clinicians-were calculated using nine different methods. The resulting effect sizes varied significantly depending on the method employed. Differences between measurement methods routinely exceeded 0.40 for individual therapists. Three methods for calculating effect sizes are recommended for moderating these differences, including two equations that show promise as valid and practical methods for use by clinicians in professional practice.

  1. Relationship among grain size, annealing twins and shape memory effect in Fe-Mn-Si based shape memory alloys

    NASA Astrophysics Data System (ADS)

    Wang, Gaixia; Peng, Huabei; Zhang, Chengyan; Wang, Shanling; Wen, Yuhua

    2016-07-01

    In order to clarify the relationship among grain size, annealing twins and the shape memory effect in Fe-Mn-Si based shape memory alloys, the Fe-21.63Mn-5.60Si-9.32Cr-5.38Ni (weight %) alloy with a grain size ranging from 48.9 μm-253.6 μm was obtained by adjusting the heating temperature or heating time after 20% cold-rolling. The densities of grain boundaries and annealing twins increase with a decrease in grain size, whereas the volume fraction and width of stress-induced ɛ martensite after 9% deformation at Ms + 10 K decrease. This result indicates that grain refinement raises the constraint effects of grain boundaries and annealing twins upon martensitic transformation. In this case, the ability to suppress the plastic deformation and facilitate the stress-induced ɛ martensite transformation deteriorates after grain refinement owing to the enhancement of the constraint effects. It is demonstrated by the result that the difference at Ms + 10 K between the critical stress for plastic yielding and that for inducing martensitic transformation is smaller for the specimen with a grain size of 48.9 μm than for the specimen with a grain size of 253.6 μm. Therefore, the shape memory effect declined by decreasing the grain size.

  2. Size Effects in Linear Elastic Fracture Mechanics

    DTIC Science & Technology

    1988-01-01

    Recent Theoretical and Experimental Developments in Fracture Mechanics", Fracture 1977, 1 (1977) 695-723. 40 S. Mindess and J. S. Nadeau," Effect of Notch...0.4 1.42 b 2.0 0.80 b Mindess and Nadeau [40], 1.0 3.98 0.86 b Mortar, 3PB 8.03 0.80 b 12.0 0.82 b 16.0 0.84 b 20.0 0.83 b Concrete, 3PB 1.0 3.54 1.08

  3. Unfolding grain size effects in barium titanate ferroelectric ceramics

    PubMed Central

    Tan, Yongqiang; Zhang, Jialiang; Wu, Yanqing; Wang, Chunlei; Koval, Vladimir; Shi, Baogui; Ye, Haitao; McKinnon, Ruth; Viola, Giuseppe; Yan, Haixue

    2015-01-01

    Grain size effects on the physical properties of polycrystalline ferroelectrics have been extensively studied for decades; however there are still major controversies regarding the dependence of the piezoelectric and ferroelectric properties on the grain size. Dense BaTiO3 ceramics with different grain sizes were fabricated by either conventional sintering or spark plasma sintering using micro- and nano-sized powders. The results show that the grain size effect on the dielectric permittivity is nearly independent of the sintering method and starting powder used. A peak in the permittivity is observed in all the ceramics with a grain size near 1 μm and can be attributed to a maximum domain wall density and mobility. The piezoelectric coefficient d33 and remnant polarization Pr show diverse grain size effects depending on the particle size of the starting powder and sintering temperature. This suggests that besides domain wall density, other factors such as back fields and point defects, which influence the domain wall mobility, could be responsible for the different grain size dependence observed in the dielectric and piezoelectric/ferroelectric properties. In cases where point defects are not the dominant contributor, the piezoelectric constant d33 and the remnant polarization Pr increase with increasing grain size. PMID:25951408

  4. Effect of DT4 Interlayer on Properties of Hot-roll Bonding TA2/Q235B Plate

    NASA Astrophysics Data System (ADS)

    Yu, Chao; Xiao, Hong; Li, Na; Qi, Zichen; Ren, Zhongkai

    2017-09-01

    In this paper, a Q235B/TA2/DT4/Q235B plate was bonded by hot-rolling in a vacuum, and the effect of including a DT4 interlayer within the TA2/Q235B plate was studied. The microstructure and properties of the composite plate at different reduction ratios were investigated by scanning electron microscopy, as well as tensile-shear, bending and tensile tests. The results show that when the reduction ratio is below 18%, the shear strength of the interface is higher with the DT4 interlayer than without it. At 35% reduction, the shear strength is similar in both cases. At a reduction ratio of 68%, with the DT4 interlayer, fracture of the bonding interface occurs on the TA2 side, whereas without the DT4 interlayer, fracture occurs on both the TA2 side and the compound layer on the interface. Including the DT4 interlayer improves the bending and tensile properties of the TA2/Q235B plate appreciably.

  5. Effects of overaging temperature on the microstructure and properties of 600 MPa cold-rolled dual-phase steel

    NASA Astrophysics Data System (ADS)

    Kuang, Chun-fu; Zheng, Zhi-wang; Zhang, Gong-ting; Chang, Jun; Zhang, Shen-gen; Liu, Bo

    2016-08-01

    C-Mn steels prepared by annealing at 800°C for 120 s and overaging at 250-400°C were subjected to pre-straining (2%) and baking treatments (170°C for 20 min) to measure their bake-hardening (BH2) values. The effects of overaging temperature on the microstructure, mechanical properties, and BH2 behavior of 600 MPa cold-rolled dual-phase (DP) steel were investigated by optical microscopy, scanning electron microscopy, and tensile tests. The results indicated that the martensite morphology exhibited less variation when the DP steel was overaged at 250-350°C. However, when the DP steel was overaged at 400°C, numerous non-martensite and carbide particles formed and yield-point elongation was observed in the tensile curve. When the overaging temperature was increased from 250 to 400°C, the yield strength increased from 272 to 317 MPa, the tensile strength decreased from 643 to 574 MPa, and the elongation increased from 27.8% to 30.6%. Furthermore, with an increase in overaging temperature from 250 to 400°C, the BH2 value initially increases and then decreases. The maximum BH2 value of 83 MPa was observed for the specimen overaged at 350°C.

  6. Repeated Habitat Disturbances by Fire Decrease Local Effective Population Size.

    PubMed

    Schrey, Aaron W; Ragsdale, Alexandria K; McCoy, Earl D; Mushinsky, Henry R

    2016-07-01

    Effective population size is a fundamental parameter in population genetics, and factors that alter effective population size will shape the genetic characteristics of populations. Habitat disturbance may have a large effect on genetic characteristics of populations by influencing immigration and gene flow, particularly in fragmented habitats. We used the Florida Sand Skink (Plestiodon reynoldsi) to investigate the effect of fire-based habitat disturbances on the effective population size in the highly threatened, severely fragmented, and fire dependent Florida scrub habitat. We screened 7 microsatellite loci in 604 individuals collected from 12 locations at Archbold Biological Station. Archbold Biological Station has an active fire management plan and detailed records of fires dating to 1967. Our objective was to determine how the timing, number, and intervals between fires affect effective population size, focusing on multiple fires in the same location. Effective population size was higher in areas that had not been burned for more than 10 years and decreased with number of fires and shorter time between fires. A similar pattern was observed in abundance: increasing abundance with time-since-fire and decreasing abundance with number of fires. The ratio of effective population size to census size was higher at sites with more recent fires and tended to decrease with time-since-last-fire. These results suggest that habitat disturbances, such as fire, may have a large effect in the genetic characteristics of local populations and that Florida Sand Skinks are well adapted to the natural fire dynamics required to maintain Florida scrub.

  7. Effect of Stretch Orientation and Rolling Orientation on the Mechanical Properties of 2195 Al-Cu-Li Alloy

    NASA Astrophysics Data System (ADS)

    Es-Said, O. S.; Parrish, C. J.; Bradberry, C. A.; Hassoun, J. Y.; Parish, R. A.; Nash, A.; Smythe, N. C.; Tran, K. N.; Ruperto, T.; Lee, E. W.; Mitchell, D.; Vinquist, C.

    2011-10-01

    Sheets of 2195 aluminum-lithium alloy were solution-treated at 507 °C for 30 min. One set was stretched to 3-5% in the 0°, 45°, and 90° angle with respect to the original rolling direction. Two other sets were rolled 6% reduction in thickness and 24% reduction in thickness in the 0°, 45°, and 90° angle with respect to the original rolling direction. All specimens were aged at 143 °C for 36 h. A second group of samples was rolled at 24 and 50% reduction in thickness after a solution treatment of 507 °C for 1 h prior to aging at 190 °C for 24 h. Tensile specimens were machined from each sheet at 0°, 45°, and 90° angles to the original grain orientation. Tensile testing was used to determine the mechanical properties and anisotropic behavior of each condition. Rolling 6% reduction in thickness in the 45° orientation yielded anisotropy of 7.6% in the yield strength.

  8. Roll-to-Roll Nanoimprint Lithography Simulations for Flexible Substrates

    NASA Astrophysics Data System (ADS)

    Spann, Andrew; Jain, Akhilesh; Bonnecaze, Roger

    2015-11-01

    UV roll-to-roll nanoimprint lithography enables the patterning of features onto a flexible substrate for bendable electronics in a continuous process. One of the most important design goals in this process is to make the residual layer thickness of the photoresist in unpatterned regions as thin and uniform as possible. Another important goal is to minimize the imprint time to maximize throughput. We develop a multi-scale model to simulate the spreading of photoresist drops as the template is pressed against the substrate. We include the effect of capillary pressure on the bending of the substrate and show how this distorts uniformity in the residual thickness layer. Our simulation code is parallelized and can simulate the flow and merging of thousands of drops. We investigate the effect of substrate tension and the initial arrangement of drops on the residual layer thickness and imprint time. We find that for a given volume of photoresist, distributing that volume to more drops initially decreases the imprint time. We conclude with recommendations for scale-up and optimal operations of roll-to-roll nanoimprint lithography systems. The authors acknowledge the Texas Advanced Computing Center at The University of Texas at Austin for providing high performance computing resources.

  9. Effect of residual stresses induced by prestressing on rolling element fatigue life

    NASA Technical Reports Server (NTRS)

    Parker, R. J.; Zaretsky, E. V.

    1972-01-01

    A mechanical prestress cycle suitable to induce compressive stress beneath the surface of the inner race of radially loaded 207-size bearings was determined. Compressive residual stress in excess 0.69 x 10 to the 9th power N/sq m (100,000 psi), as measured by X-ray diffraction, were induced at the depth of maximum shearing stress. The prestress cycle consisted of running the bearings for 25 hours at 2750 rpm at a radial load which produced a maximum Hertz stress of 3.3 x 10 to the 9th power N/sq m (480,000 psi) at the contact of the inner race and the heaviest loaded ball. Bearings subjected to this prestress cycle and subsequently fatigue tested gave a 10 percent fatigue life greater than twice that of a group of baseline bearings.

  10. Origins of rolling friction

    NASA Astrophysics Data System (ADS)

    Cross, Rod

    2017-09-01

    When a hard object rolls on a soft surface, or vice versa, rolling friction arises from deformation of the soft object or the soft surface. The friction force can be described in terms of an offset in the normal reaction force or in terms of energy loss arising from the deformation. The origin of the friction force itself is not entirely clear. It is investigated qualitatively in this paper by rolling a steel ball on soft foam and by rolling a foam cylinder on a hard surface. The deformation of the foam was observed visually, providing simple insights into the origin of the friction force.

  11. Unit bias. A new heuristic that helps explain the effect of portion size on food intake.

    PubMed

    Geier, Andrew B; Rozin, Paul; Doros, Gheorghe

    2006-06-01

    People seem to think that a unit of some entity (with certain constraints) is the appropriate and optimal amount. We refer to this heuristic as unit bias. We illustrate unit bias by demonstrating large effects of unit segmentation, a form of portion control, on food intake. Thus, people choose, and presumably eat, much greater weights of Tootsie Rolls and pretzels when offered a large as opposed to a small unit size (and given the option of taking as many units as they choose at no monetary cost). Additionally, they consume substantially more M&M's when the candies are offered with a large as opposed to a small spoon (again with no limits as to the number of spoonfuls to be taken). We propose that unit bias explains why small portion sizes are effective in controlling consumption; in some cases, people served small portions would simply eat additional portions if it were not for unit bias. We argue that unit bias is a general feature in human choice and discuss possible origins of this bias, including consumption norms.

  12. Permeability of packed coal beds: The effect of particle size distribution, particle size and coal type

    SciTech Connect

    Greeff, S.C.; Slaghuis, J.H.; Walt, T.J. van der

    1998-12-31

    Sasol operates 97 Lurgi type gasifiers for the production of syngas using lump coal obtained from 7 captive coal mines. Permeability of packed coal beds of the coal has been identified as one of the major variables affecting stable operation which in turn affects maximum coal throughput and gas production. A tenth scale instrumented cold perspex model simulating a gasifier was constructed in which the pressure drop per unit bed length for a given gas flow could be measured. The effect of particle size distribution, particle size and coal type on the pressure drop (and hence permeability) was measured. The results were augmented by measuring void fractions as well as shape factors for the different coal types. The effect of size segregation during filling of the scale model was also investigated. Results have shown that bed permeability is strongly affected by the 3 variables investigated. The change in void fraction was found to be very small and could not be linked to the change in permeability. Size segregation resulted in a difference in gas flow rate between the center of the coal bed and against the wall of the model. The significance of the observations are discussed in terms of gasifier stability, optimum pressure drop and the effect of thermal size stability of coal upon entering the gasifier.

  13. Free-flight Investigation at Transonic and Supersonic Speeds of the Rolling Effectiveness of a 42.7 Degree Sweptback Wing Having Partial-span Ailerons

    NASA Technical Reports Server (NTRS)

    Sandahl, Carl A

    1948-01-01

    An investigation of the rolling effectiveness at transonic and supersonic speeds of partial-span ailerons on a 42.7 degree sweptback wing having symmetrical circular-arc airfoil sections of 10-percent thickness ratio normal to the wing quarter-chord line has been made by means of rocket-propelled test vehicles. The results are compared with results of a supersonic wind-tunnel test at Mach number 1.9.

  14. Effects of prolonged weightlessness on self-motion perception and eye movements evoked by roll and pitch

    NASA Technical Reports Server (NTRS)

    Reschke, Millard F.; Parker, Donald E.

    1987-01-01

    Seven astronauts reported translational self-motion during roll simulation 1-3 h after landing following 5-7 d of orbital flight. Two reported strong translational self-motion perception when they performed pitch head motions during entry and while the orbiter was stationary on the runway. One of two astronauts from whom adequate data were collected exhibited a 132-deg shift in the phase angle between roll stimulation and horizontal eye position 2 h after landing. Neither of two from whom adequate data were collected exhibited increased horizontal eye movement amplitude or disturbance of voluntary pitch or roll body motion immediately postflight. These results are generally consistent with an otolith tilt-translation reinterpretation model and are being applied to the development of apparatus and procedures intended to preadapt astronauts to the sensory rearrangement of weightlessness.

  15. Effect of Surface Densification on the Microstructure and Mechanical Properties of Powder Metallurgical Gears by Using a Surface Rolling Process

    PubMed Central

    Peng, Jingguang; Zhao, Yan; Chen, Di; Li, Kiade; Lu, Wei; Yan, Biao

    2016-01-01

    Powder metallurgy (PM) components are widely used in the auto industry due to the advantage of net-shape forming, low cost, and high efficiency. Still, usage of PM components is limited in the auto industry when encountering rigorous situations, like heavy load, due to lower strength, hardness, wear resistance, and other properties compared to wrought components due to the existence of massive pores in the PM components. In this study, through combining the powder metallurgy process and rolling process, the pores in the PM components were decreased and a homogenous densified layer was formed on the surface, which resulted in the enhancement of the strength, hardness, wear resistance, and other properties, which can expand its range of application. In this paper, we study the impact of different rolling feeds on the performance of the components’ surfaces. We found that with the increase of the rolling feed, the depth of the densified layer increased. PMID:28773970

  16. Effect of double vacuum melting and retained austenite on rolling-element fatigue life of AMS 5749 bearing steel

    NASA Technical Reports Server (NTRS)

    Parker, R. J.; Hodder, R. S.

    1977-01-01

    AMS 5749 steel combines the tempering, hot hardness, and hardness retention characteristics of AISI M-50 steel with the corrosion and oxidation resistance of AISI 440C stainless steel. The five-ball fatigue tester was used to evaluate the rolling-element fatigue life of AMS 5749. Double vacuum melting (vacuum induction melting plus vacuum arc remelting, VIM-VAR) produced AMS 5749 material with a rolling-element fatigue life at least 14 times that of vacuum induction melting alone. The VIM-VAR AMS 5749 steel balls gave lives from 6 to 12 times greater than VIM-VAR AISI M-50 steel balls. The highest level of retained austenite, 14.6 percent, was significantly detrimental to rolling-element fatigue life relative to the intermediate level of 11.1 percent.

  17. Effect of Surface Densification on the Microstructure and Mechanical Properties of Powder Metallurgical Gears by Using a Surface Rolling Process.

    PubMed

    Peng, Jingguang; Zhao, Yan; Chen, Di; Li, Kiade; Lu, Wei; Yan, Biao

    2016-10-19

    Powder metallurgy (PM) components are widely used in the auto industry due to the advantage of net-shape forming, low cost, and high efficiency. Still, usage of PM components is limited in the auto industry when encountering rigorous situations, like heavy load, due to lower strength, hardness, wear resistance, and other properties compared to wrought components due to the existence of massive pores in the PM components. In this study, through combining the powder metallurgy process and rolling process, the pores in the PM components were decreased and a homogenous densified layer was formed on the surface, which resulted in the enhancement of the strength, hardness, wear resistance, and other properties, which can expand its range of application. In this paper, we study the impact of different rolling feeds on the performance of the components' surfaces. We found that with the increase of the rolling feed, the depth of the densified layer increased.

  18. The effect of cold-rolling on the magnetic properties of non-oriented silicon steel sheets

    SciTech Connect

    Huang, B.Y.; Yamamoto, K.; Kaido, C.; Yamashiro, Y.

    1999-09-01

    Non-oriented 3% silicon steel sheets were cold-rolled to 0.1 mm thick by various methods, and then they were finally annealed in an argon atmosphere for 1.5 hours at 900 C with a cooling rate of 0.025 C/s. Their magnetic properties changed depending on cold-rolling method used. A sample which had magnetic two-easy-directions with strong (100) cubic texture was obtained in the following way. The sample was alternately cold-rolled in two perpendicular directions L and T, and was also subjected to an intermediate anneal. The average grain diameter of the sample was 57 {micro}m. Its magnetic induction at 800 A/m was 1.65 T in the L direction, and 1.62 T in T direction, respectively.

  19. Short communication: Effects of prepartum diets supplemented with rolled oilseeds on Brix values and fatty acid profile of colostrum.

    PubMed

    Salehi, R; Ambrose, D J; Oba, M

    2016-05-01

    The objective of this study was to evaluate effects of oilseeds supplemented in prepartum diets on colostrum quality. Thirty-nine dry pregnant Holstein cows (14 primiparous and 25 multiparous cows) were blocked by body condition score and parity and assigned to 1 of 3 experimental diets containing rolled oilseeds at 8% of dietary dry matter (canola seed or sunflower seed) or no oilseed (control) at 35 d before the expected calving date. Canola seed is high in oleic acid and sunflower seed is high in linoleic acid content. Colostrum samples were collected at the first milking after calving, and concentrations of nutrient composition, fatty acid profile, and Brix value (an indicator IgG concentration) were determined. Cows fed sunflower seeds before calving produced colostrum with greater crude protein content (15.0 vs. 12.9%), colostral Brix values (24.3 vs. 20.3%), and conjugated linoleic acid concentration (18:2 cis-9,trans-11; 0.64 vs. 0.48%) compared with those fed canola seed. Positive effects of feeding sunflower seed might be mediated by ruminal metabolism of linoleic acid and subsequent enhanced production of conjugated linoleic acid. Oilseed supplementation in prepartum diets of dairy cows also altered fatty acid profile of colostrum in a way to reflect fatty acid profile of the supplemented oilseeds except for oleic acid. In conclusion, prepartum feeding of sunflower seed increased colostral Brix value, an indicator of colostral IgG concentration, compared with that of canola seed, but its mode of action and effects on health and productivity of calves need to be investigated.

  20. The Effect of Size on Spin Glass Systems

    NASA Astrophysics Data System (ADS)

    Lane, Katrina R.

    There has been considerable interest in the effect of sample size on the Kondo resistance contribution in metals. Previous work in this lab has suggested that the Kondo slope is suppressed with decreasing size because of the confinement of electrons to a volume smaller than the spin compensation cloud that forms in these systems. Simultaneously, there has been a fair amount of research on the effect of size on the freezing temperature of a spin glass. But many questions remain. Is the cloud picture correct vs. other competing theories? Will the suppression of the Kondo slope persist in more concentrated samples? How does size effect the inter-impurity interaction in these samples? The purpose of this work is to integrate the results on Kondo and spin glass systems and to present a single underlying physical explanation for the size effects in these systems. We have performed resistance measurements on magnetic impurities (Cr) in a noble metal host (Cu) using various sample sizes. We present evidence suggesting that the resistance maximum is a legitimate way to characterize our films. We show that it is possible to examine the effects of size on the Kondo slope even in these concentrated samples and also in the presence of an applied field. The magnetic field is used to characterize the inter-impurity interaction. We present data on the size effect and the appropriate length scales for the modification of the inter -impurity interaction. We find supporting evidence for our results in studies on the magnetoresistivity and on the effect of overlayers on pure spin glasses. In addition, we examine the effect of concentration. We compare to a theory of the resistance maximum and find that our results agree well with expected behavior. We conclude that both the Kondo effect and the inter-impurity interaction are suppressed by size because of the confinement of the electrons to limited volumes and hope to convince the reader likewise.

  1. Minimizing finite-size effects in artificial resonance tunneling structures.

    PubMed

    Chak, Philip; Sipe, J E

    2006-09-01

    We consider finite-size effects in coupled cavity structures. Starting with microring resonator structures well described by transfer matrices, we obtain conditions that lead to the minimization of finite-size effects. Our approach does not require numerical optimization and requires only slight modification of design parameters guided by closed-form analytical expressions. Using a Breit-Wigner scattering formalism, we demonstrate that the scheme can be used to minimize finite-size effects in a general class of coupled cavity structures. The strength of the present technique lies in its simplicity and its applicability to a wide variety of structures described by tight-binding formalisms.

  2. Effective population size and inbreeding depression on litter size in rabbits. A case study.

    PubMed

    Ragab, M; Sánchez, J P; Baselga, M

    2015-02-01

    The purpose of this study is to use demographic and litter size data on four Spanish maternal lines of rabbits (A, V, H and LP), as a case study, in order to: (i) estimate the effective population size of the lines, as a measure of the rate of increase of inbreeding, and (ii) study whether the inbreeding effect on litter size traits depends on the pattern of its accumulation over time. The lines are being selected for litter size at weaning and are kept closed at the same selection nucleus under the same selection and management programme. The study considered 47,794 l and a pedigree of 14,622 animals. Some practices in mating and selection management allow an increase of the inbreeding coefficient lower than 0.01 per generation in these lines of around 25 males and 125 females. Their effective population size (Ne) was around 57.3, showing that the effect of selection, increasing the inbreeding, was counterbalanced by the management practices, intended to reduce the rate of inbreeding increase. The inbreeding of each individual was broken down into three components: old, intermediate and new inbreeding. The coefficients of regression of the old, intermediate and new inbreeding on total born (TB), number born alive (NBA) and number weaned (NW) per litter showed a decreasing trend from positive to negative values. Regression coefficients significantly different from zero were those for the old inbreeding on TB (6.79 ± 2.37) and NBA (5.92 ± 2.37). The contrast between the coefficients of regression between the old and new inbreeding were significant for the three litter size traits: 7.57 ± 1.72 for TB; 6.66 ± 1.73 for NBA and 5.13 ± 1.67 for NW. These results have been interpreted as the combined action of purging unfavourable genes and artificial selection favoured by the inbreeding throughout the generations of selection.

  3. The Effect of Town Size and Location on Retail Sales.

    ERIC Educational Resources Information Center

    Scott, John T., Jr.; Johnson, James D.

    Study objectives were to: determine the range of retail goods provided by different size urban places in two predominantly different rural states (Illinois and Iowa); investigate the relationship of distance to larger urban places and the impact on retail offerings of small towns; estimate the effects of location (i.e., proximity) and town size on…

  4. Effect of particle size on enzymatic hydrolysis of pretreated Miscanthus

    USDA-ARS?s Scientific Manuscript database

    Particle size reduction is a crucial factor in transportation logistics as well as cellulosic conversion. The effect of particle size on enzymatic hydrolysis of pretreated Miscanthus x giganteus was determined. Miscanthus was ground using a hammer mill equipped with screens having 0.08, 2.0 or 6.0...

  5. The Effect of Primary School Size on Academic Achievement

    ERIC Educational Resources Information Center

    Gershenson, Seth; Langbein, Laura

    2015-01-01

    Evidence on optimal school size is mixed. We estimate the effect of transitory changes in school size on the academic achievement of fourth-and fifth-grade students in North Carolina using student-level longitudinal administrative data. Estimates of value-added models that condition on school-specific linear time trends and a variety of…

  6. Research on the Effect of Class Size on Academic Achievement.

    ERIC Educational Resources Information Center

    Vignocchi, Nello

    Studies presented indicate that there is a lack of consistent evidence on the effect of class size on academic achievement. Previous research designs have not adequately accounted for all of the possible influential variables. Future research designs must be more rigorous in their consideration of methods of instruction, student age, class size,…

  7. A Practical Method of Policy Analysis by Estimating Effect Size

    ERIC Educational Resources Information Center

    Phelps, James L.

    2011-01-01

    The previous articles on class size and other productivity research paint a complex and confusing picture of the relationship between policy variables and student achievement. Missing is a conceptual scheme capable of combining the seemingly unrelated research and dissimilar estimates of effect size into a unified structure for policy analysis and…

  8. How Methodological Features Affect Effect Sizes in Education

    ERIC Educational Resources Information Center

    Cheung, Alan; Slavin, Robert

    2016-01-01

    As evidence-based reform becomes increasingly important in educational policy, it is becoming essential to understand how research design might contribute to reported effect sizes in experiments evaluating educational programs. The purpose of this study was to examine how methodological features such as types of publication, sample sizes, and…

  9. Multilayer roll bonded aluminium foil: processing, microstructure and flow stress

    SciTech Connect

    Barlow, C.Y.; Nielsen, P.; Hansen, N

    2004-08-02

    Bulk aluminium has been produced by warm-rolling followed by cold-rolling of commercial purity (99% purity) aluminium foil. The bonding appeared perfect from observation with the naked eye, light and transmission electron microscopy. By comparison with bulk aluminium of similar purity (AA1200) rolled to a similar strain (90%RA), the roll-bonded metal showed a much higher density of high-angle grain boundaries, similar strength and improved thermal stability. This study has implications for a number of applications in relation to the processing of aluminium. Roll bonding is of interest as a method for grain size refinement; oxide-containing materials have increased strength, enhanced work-hardening behaviour, and exhibit alterations in recrystallisation behaviour. The behaviour of the hard oxide film is of interest in aluminium processing, and has been investigated by characterising the size and distribution of oxide particles in the roll-bonded samples.

  10. Pattern size tolerance of reverse offset printing: a proximity deformation effect related to local PDMS slipping

    NASA Astrophysics Data System (ADS)

    Kusaka, Yasuyuki; Kanazawa, Shusuke; Koutake, Masayoshi; Ushijima, Hirobumi

    2017-10-01

    We investigated the shape integrity of silver nanoparticle ink patterns formed by reverse offset printing, focusing particularly on the proximity effect of neighbouring patterns due to the local deformation of a polydimethylsiloxane (PDMS) blanket during contact with a hard cliché. We performed printing tests using a cliché having circular patterns with smaller neighbouring circles located at various distances (2–20 µm), and the results revealed that as we decrease the thickness of PDMS and the inter-pattern gap distance, and as we increase the printing indentations, the shape integrity of the printed pattern was worsened. A complementary numerical simulation of PDMS deformations suggested that the pattern distortion during the contact with clichés was caused by the horizontal deformation of PDMS during the printing, which becomes a significant burden when the uplifted region of PDMS is closer to the gap distance of each pattern. Our analysis further indicates that during printing, there is slipping of the ink at the PDMS interface. In addition, we examined the effects of a synchronization mismatch in a roll-to-sheet printing on the pattern size tolerance. The magnitude of the size distortions was severely influenced not only by the mismatch ratio but also by the nip width. This result verifies the scraping of the ink accompanied by the slipping of the PDMS during the printing process, and thereby determines the size tolerance of printed patterns in reverse offset printing. Finally, we discuss the optimization of process parameters to ensure the size integrity of reverse offset printing.

  11. Microstructural evolution in warm-rolled and cold-rolled strip cast 6.5 wt% Si steel thin sheets and its influence on magnetic properties

    NASA Astrophysics Data System (ADS)

    Wang, Xianglong; Liu, Zhenyu; Li, Haoze; Wang, Guodong

    2017-07-01

    6.5 wt% Si steel thin sheets were usually fabricated by warm rolling. In our previous work, 6.5 wt% Si steel thin sheets with good magnetic properties had been successfully fabricated by cold rolling based on strip casting. In the present work, the main purposes were to find out the influences of warm rolling and cold rolling on microstructures and magnetic properties of the thin sheets with the thickness of 0.2 mm, and to confirm which rolling method was more suitable for fabricating 6.5 wt% Si steel thin sheets. The results showed that the cold rolled sheet could obtain good surface quality and flatness, while the warm rolled sheet could not. The intensity of γ-fiber rolling texture (<1 1 1>//ND) of cold rolled specimen was weaker than that of the warm rolled specimen, especially for the {1 1 1}<1 1 2> component at surface layer and {1 1 1}<1 1 0> component at center layer. After the same annealing treatment, the cold rolled specimen, which had higher stored energy and weaker intensity of γ-fiber rolling texture, could obtain smaller recrystallization grain size, weaker intensity of γ-fiber recrystallization texture and stronger intensity of λ-fiber recrystallization texture. Therefore, due to the good surface quality, smaller recrystallization grain size and optimum recrystallization texture, the cold rolled specimen possessed improved magnetic properties, and cold rolling should be more suitable for fabricating 6.5 wt% Si steel thin sheets.

  12. Roll over Weismann: extracellular vesicles in the transgenerational transmission of environmental effects.

    PubMed

    Eaton, Sally A; Jayasooriah, Navind; Buckland, Michael E; Martin, David Ik; Cropley, Jennifer E; Suter, Catherine M

    2015-10-01

    The ability of environmental exposures to induce phenotypic change across multiple generations of offspring has gathered an enormous amount of interest in recent years. There are by now many examples of nongenetic transgenerational effects of environmental exposures, covering a broad range of stressors. Available evidence indicates that epigenetic inheritance may mediate at least some of these transgenerational effects, but how environmental exposures induce changes to the epigenome of the germline is unknown. One possibility is that exposed somatic cells can communicate their exposures to the germline to induce a stable change. In this Perspective, we propose that extracellular vesicles shed by somatic cells represent a credible means by which environmental experience could effect a transmissible epigenetic change in the germline, leading to the inheritance of acquired traits.

  13. Where Class Size Really Matters: Class Size and Student Ratings of Instructor Effectiveness

    ERIC Educational Resources Information Center

    Bedard, Kelly; Kuhn, Peter

    2008-01-01

    We examine the impact of class size on student evaluations of instructor performance using data on all economics classes offered at the University of California, Santa Barbara from Fall 1997 to Spring 2004. A particular strength of this data is the opportunity to control for both instructor and course fixed effects. In contrast to the literature…

  14. Multiple rolling/crimping effects on termination of two summer cover crops in a conservation system

    USDA-ARS?s Scientific Manuscript database

    A field experiment was initiated in the 2015 growing season at the USDA-NSDL to determine the effectiveness of a prototype two-stage roller/crimper in mechanical termination of two summer cover crops intended for organic systems. The experiment was a randomized complete block design with four replic...

  15. Acute effects of anterior thigh foam rolling on hip angle, knee angle, and rectus femoris length in the modified Thomas test

    PubMed Central

    Lehman, Gregory J.; Contreras, Bret; Beardsley, Chris; Chung, Bryan; Feser, Erin H.

    2015-01-01

    Background. Foam rolling has been shown to acutely increase range of motion (ROM) during knee flexion and hip flexion with the experimenter applying an external force, yet no study to date has measured hip extensibility as a result of foam rolling with controlled knee flexion and hip extension moments. The purpose of this study was to investigate the acute effects of foam rolling on hip extension, knee flexion, and rectus femoris length during the modified Thomas test. Methods. Twenty-three healthy participants (male = 7; female = 16; age = 22 ± 3.3 years; height = 170 ± 9.18 cm; mass = 67.7 ± 14.9 kg) performed two, one-minute bouts of foam rolling applied to the anterior thigh. Hip extension and knee flexion were measured via motion capture before and after the foam rolling intervention, from which rectus femoris length was calculated. Results. Although the increase in hip extension (change = +1.86° (+0.11, +3.61); z(22) = 2.08; p = 0.0372; Pearson’s r = 0.43 (0.02, 0.72)) was not due to chance alone, it cannot be said that the observed changes in knee flexion (change = −1.39° (−5.53, +2.75); t(22) = −0.70; p = 0.4933; Cohen’s d = − 0.15 (−0.58, 0.29)) or rectus femoris length (change = −0.005 (−0.013, +0.003); t(22) = −1.30; p = 0.2070; Cohen’s d = − 0.27 (−0.70, 0.16)) were not due to chance alone. Conclusions. Although a small change in hip extension was observed, no changes in knee flexion or rectus femoris length were observed. From these data, it appears unlikely that foam rolling applied to the anterior thigh will improve passive hip extension and knee flexion ROM, especially if performed in combination with a dynamic stretching protocol. PMID:26421244

  16. The Effects of High-lift Devices on the Low-speed Stability of a Tapered 37.5 Degree Sweptback Wing of Aspect Ratio 3 in Straight and Rolling Flow

    NASA Technical Reports Server (NTRS)

    Queijo, M J; Lichtenstein, Jacob H

    1948-01-01

    Contains results of tunnel tests to determine effects of various combinations of split flaps, slats, and nose slats on the stability characteristics of a tapered 37.5 degree sweptback wing of aspect ratio 3 in straight and rolling flow.

  17. Effect of environmental torques on short-term attitude prediction for a rolling-wheel spacecraft in a sun-synchronous orbit

    NASA Technical Reports Server (NTRS)

    Hodge, W. F.

    1972-01-01

    A numerical evaluation and an analysis of the effects of environmental disturbance torques on the attitude of a hexagonal cylinder rolling wheel spacecraft were performed. The resulting perturbations caused by five such torques were found to be very small and exhibited linearity such that linearized equations of motion yielded accurate results over short periods and the separate perturbations contributed by each torque were additive in the sense of superposition. Linearity of the torque perturbations was not affected by moderate system design changes and persisted for torque-to-angular momentum ratios up to 100 times the nominal expected value. As these conditions include many possible applications, similar linear behavior might be anticipated for other rolling-wheel spacecraft.

  18. Understanding Rolle's Theorem

    ERIC Educational Resources Information Center

    Parameswaran, Revathy

    2009-01-01

    This paper reports on an experiment studying twelfth grade students' understanding of Rolle's Theorem. In particular, we study the influence of different concept images that students employ when solving reasoning tasks related to Rolle's Theorem. We argue that students' "container schema" and "motion schema" allow for rich…

  19. Inferring Past Effective Population Size from Distributions of Coalescent Times

    PubMed Central

    Gattepaille, Lucie; Günther, Torsten; Jakobsson, Mattias

    2016-01-01

    Inferring and understanding changes in effective population size over time is a major challenge for population genetics. Here we investigate some theoretical properties of random-mating populations with varying size over time. In particular, we present an exact solution to compute the population size as a function of time, Ne(t), based on distributions of coalescent times of samples of any size. This result reduces the problem of population size inference to a problem of estimating coalescent time distributions. To illustrate the analytic results, we design a heuristic method using a tree-inference algorithm and investigate simulated and empirical population-genetic data. We investigate the effects of a range of conditions associated with empirical data, for instance number of loci, sample size, mutation rate, and cryptic recombination. We show that our approach performs well with genomic data (≥ 10,000 loci) and that increasing the sample size from 2 to 10 greatly improves the inference of Ne(t) whereas further increase in sample size results in modest improvements, even under a scenario of exponential growth. We also investigate the impact of recombination and characterize the potential biases in inference of Ne(t). The approach can handle large sample sizes and the computations are fast. We apply our method to human genomes from four populations and reconstruct population size profiles that are coherent with previous finds, including the Out-of-Africa bottleneck. Additionally, we uncover a potential difference in population size between African and non-African populations as early as 400 KYA. In summary, we provide an analytic relationship between distributions of coalescent times and Ne(t), which can be incorporated into powerful approaches for inferring past population sizes from population-genomic data. PMID:27638421

  20. Finite-size effects in nanocomposite thin films and fibers

    NASA Astrophysics Data System (ADS)

    Stevens, D. R.; Skau, E. W.; Downen, L. N.; Roman, M. P.; Clarke, L. I.

    2011-08-01

    Monte Carlo simulations of finite-size effects for continuum percolation in three-dimensional, rectangular sample spaces filled with spherical particles were performed. For samples with any dimension less than 10-20 times the particle diameter, finite-size effects were observed. For thin films in the finite-size regime, percolation across the thin direction of the film gave critical volume fraction (pc) values that differed from those along the plane of the film. Simulations perpendicular to the film for very thin samples resulted in pc values lower than the classical limit of ˜29% (for spheres in a three-dimensional matrix) which increased with film thickness. For percolation along thin films, while holding film thickness constant, pc increased with increasing sample size, which is a modification of the finite-sized scaling effect for cubic samples. For samples with a large aspect ratio (fibers) and a finite-sized cross-sectional area, the critical volume fraction increased with sample length, as the sample became quasi-one-dimensional. The results are discussed in the context of adding volume along or perpendicular to the percolation direction. From an experimental perspective, these findings indicate that sample shape, as well as relative size, influences percolation in the finite-size regime.

  1. The effects of recrystallization texture and grain size on magnetic properties of 6.5 wt% Si electrical steel

    NASA Astrophysics Data System (ADS)

    Pan, Hongjiang; Zhang, Zhihao; Xie, Jianxin

    2016-03-01

    Cold rolled sheets of high silicon electrical steel (Fe-6.5 wt% Si alloy) with thicknesses of 0.2-0.4 mm were fabricated by directional solidification and rolling, and the microstructure, texture and magnetic properties of the sheets annealed at 700-1300 °C for 1 h were investigated. The roles of recrystallization texture and grain size in influencing the magnetic induction and core loss were clarified. All the samples had strong {100} recrystallization texture with volume fraction of 18.3-47.3% and exhibited high magnetic induction and low core loss. For the samples with a thickness of 0.2 mm after annealing at 800-1200 °C, the magnetic induction B8 and the core loss P10/50 reached 1.273-1.378 T and 0.49-0.84 W/kg, respectively. The grain size played a much more important role in the core loss than recrystallization texture. The average grain size to seek minimum core loss P10/50 was 536-615 μm in the high silicon electrical steel sheets with thicknesses of 0.2-0.4 mm, which was larger than 100-200 μm for the electrical steel with common silicon content. The magnetic induction B8 of the samples improved with an enhancement of {100} recrystallization texture, but reduced with an increase of average grain size. The effect of recrystallization texture on the magnetic induction B8 was much greater than that of grain size.

  2. Finite-size effect in lattice QCD hadron spectroscopy

    SciTech Connect

    Fukugita, M.; Mino, H.; Okawa, M.; Ukawa, A. Faculty of Engineering, Yamanashi University, Kofu 400 National Laboratory for High Energy Physics , Ibaraki 305 Institute of Physics, University of Tsukuba, Ibaraki 305 )

    1992-02-10

    A hadron spectrum calculation with two light dynamical quark flavors was carried out with the Kogut-Susskind quark action at {beta}=5.7 on lattices of spatial size 8{sup 3}, 12{sup 3}, and 20{sup 3} for {ital m}{sub {ital q}}=0.01 and 0.02 in lattice units, with emphasis given to a systematic study of the finite-lattice-size effect. It is found that hadron masses on a 16{sup 3} spatial lattice at this {beta} still suffer from a significant finite-lattice effect at least for {ital m}{sub {ital q}}=0.01, showing the importance of a quantitative control over the finite-size effect in comparing simulation results with the experimental hadron masses even for a fairly large lattice. A comparison is also made to the analytic prediction for the finite-size effect from chiral perturbation theory.

  3. Economic Effects of Increased Control Zone Sizes in Conflict Resolution

    NASA Technical Reports Server (NTRS)

    Datta, Koushik

    1998-01-01

    A methodology for estimating the economic effects of different control zone sizes used in conflict resolutions between aircraft is presented in this paper. The methodology is based on estimating the difference in flight times of aircraft with and without the control zone, and converting the difference into a direct operating cost. Using this methodology the effects of increased lateral and vertical control zone sizes are evaluated.

  4. Effect of particle size on the alcohol yield from corn

    SciTech Connect

    Gantt, R.E.; Hegg, R.O.

    1981-01-01

    A laboratory study was conducted to determine the effect of particle size on the conversion of corn to ethanol. Standard analytical procedures were used to measure carbohydrates, sugar, and alcohol. The highest yield obtained was 2.4 gal/bu with the average being 1.8 gal/bu. The results showed that particle size has little effect on alcohol yield. 7 refs.

  5. Rolled-crimped winter rye cover effects on hand-weeding times and fruit yield and quality of cucurbits

    USDA-ARS?s Scientific Manuscript database

    Fruit and vegetables produced without pesticides are in demand by some segments of society. However, weeds often are deleterious in such crops, and managing them without herbicides is difficult. Stale seedbeds and rolled-crimped winter rye cover crops are non-chemical methods that may help manage we...

  6. Influence of motion coupling and nonlinear effects on parametric roll for a floating production storage and offloading platform

    PubMed Central

    Greco, M.; Lugni, C.; Faltinsen, O. M.

    2015-01-01

    Occurrence and features of parametric roll (PR) on a weather-vaning floating production storage and offloading (FPSO) platform with a turret single-point mooring-line system are examined. The main focus is on the relevance of motions coupling and nonlinear effects on this phenomenon and on more general unstable conditions as well as on the occurrence and severity of water on deck. This work was motivated by recent experiments on an FPSO model without mooring systems highlighting the occurrence of parametric resonance owing to roll–yaw coupling. A three-dimensional numerical hybrid potential-flow seakeeping solver was able to capture this behaviour. The same method, extended to include the mooring lines, is adopted here to investigate the platform behaviour for different incident wavelengths, steepnesses, headings, locations of the turret and pretensions. From the results, sway and yaw tend to destabilize the system, also bringing chaotic features. The sway–roll–yaw coupling widens the existence region of PR resonance and increases PR severity; it also results in a larger amount of shipped water, especially at smaller wavelength-to-ship length ratio and larger steepness. The chaotic features are excited when a sufficiently large yaw amplitude is reached. Consistently, a simplified stability analysis showed the relevance of nonlinear-restoring coefficients, first those connected with the sway–yaw coupling then those associated with the roll–yaw coupling, both destabilizing. From the stability analysis, the system is unstable for all longitudinal locations of the turret and pre-tensions examined, but the instability weakens as the turret is moved forward, and the pre-tension is increased. The use of a suitable dynamic-positioning system can control the horizontal motions, avoiding the instability. PMID:25512590

  7. Sway, Yaw, and Roll Coupling Effects on Straight Line Stability of Submersibles

    DTIC Science & Technology

    1993-03-01

    CR =ZgW Substituting in Equations (4.3a) - (4.3e) yields: A = ARAL + (MZg)2z (~- Ni) (4.4a) B = ARBL + BRAL + (MZg) 2 (Nr -MXg)(U) + (4.4b) (MZg )I...neglected; the effects of doing this are small and may be seen in Figures 32 and 33. This reduces the coefficients to: A = ARAL (4.5a) B = ARBL + BRAL + a (Xg...KrU)] (4.6f) K2 = (MZgU 2)(NrKv - NvKr) -- (4.6g) Carrying through the computations iesults in ýhe following expressions: (ARAL) ao4 + ( ARBL +BRAL+K1

  8. Effects of ultra-clean and centrifugal filtration on rolling-element bearing life

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.; Moyer, D. W.; Needelman, W. M.

    1981-01-01

    Fatigue tests were conducted on groups of 65-mm bore diameter deep-groove ball bearings in a MIL-L-23699 lubricant under two levels of filtration to determine the upper limit in bearing life under the strictest possible lubricant cleanliness conditions. Bearing fatigue lives, surface distress and weight loss were compared to previous bearing fatigue tests in contaminated and noncontaminated oil filters having absolute removal ratings of 3, 30, 49, and 105 microns, with lubricant and sump temperatures maintained at 347 K. Ultra clean lubrication was found to produce bearing fatigue lives that were approximately twice that obtained in previous tests with contaminated oil using 3 micron absolute filtration. It was also observed that the centrifugal oil filter has the same effectiveness as a 30 micron absolute filter in preventing surface damage.

  9. Effects of Mesh Size on Sieved Samples of Corophium volutator

    NASA Astrophysics Data System (ADS)

    Crewe, Tara L.; Hamilton, Diana J.; Diamond, Antony W.

    2001-08-01

    Corophium volutator (Pallas), gammaridean amphipods found on intertidal mudflats, are frequently collected in mud samples sieved on mesh screens. However, mesh sizes used vary greatly among studies, raising the possibility that sampling methods bias results. The effect of using different mesh sizes on the resulting size-frequency distributions of Corophium was tested by collecting Corophium from mud samples with 0·5 and 0·25 mm sieves. More than 90% of Corophium less than 2 mm long passed through the larger sieve. A significantly smaller, but still substantial, proportion of 2-2·9 mm Corophium (30%) was also lost. Larger size classes were unaffected by mesh size. Mesh size significantly changed the observed size-frequency distribution of Corophium, and effects varied with sampling date. It is concluded that a 0·5 mm sieve is suitable for studies concentrating on adults, but to accurately estimate Corophium density and size-frequency distributions, a 0·25 mm sieve must be used.

  10. Evaluation of the effectiveness of the use of horizontal and vertical rolls in the “Rolling-pressing” process on the basis of the stress-strain state studying

    NASA Astrophysics Data System (ADS)

    Lezhnev, S.; Naizabekov, A.; Panin, E.; Koinov, T.; Mazur, I.; Arbuz, A.

    2017-02-01

    In this work was performed a comparative analysis of the efficiency of horizontal and vertical rolls in the “rolling-pressing” process. The comparison was performed based on the study of stress-strain state of both variants with the aid of computer simulation in the program DEFORM-3D based on the finite element method. For analysis of the stress state was used the Lode-Nadai coefficient, allowing you to determine which type of deformation is realized at a specific point – tension, compression or shear. For analysis of the strain state was used equivalent strain, which allows to estimate the common level of accumulated strain. In the comparative analysis of parameters of SSS was revealed that the use of vertical rolls at the exit from the matrix during “rolling-pressing” process, allows you to achieve a more favorable distribution of deformation along the entire length of the deformable workpiece.

  11. A quality by design approach to investigate the effect of mannitol and dicalcium phosphate qualities on roll compaction.

    PubMed

    Souihi, Nabil; Dumarey, Melanie; Wikström, Håkan; Tajarobi, Pirjo; Fransson, Magnus; Svensson, Olof; Josefson, Mats; Trygg, Johan

    2013-04-15

    Roll compaction is a continuous process for solid dosage form manufacturing increasingly popular within pharmaceutical industry. Although roll compaction has become an established technique for dry granulation, the influence of material properties is still not fully understood. In this study, a quality by design (QbD) approach was utilized, not only to understand the influence of different qualities of mannitol and dicalcium phosphate (DCP), but also to predict critical quality attributes of the drug product based solely on the material properties of that filler. By describing each filler quality in terms of several representative physical properties, orthogonal projections to latent structures (OPLS) was used to understand and predict how those properties affected drug product intermediates as well as critical quality attributes of the final drug product. These models were then validated by predicting product attributes for filler qualities not used in the model construction. The results of this study confirmed that the tensile strength reduction, known to affect plastic materials when roll compacted, is not prominent when using brittle materials. Some qualities of these fillers actually demonstrated improved compactability following roll compaction. While direct compression qualities are frequently used for roll compacted drug products because of their excellent flowability and good compaction properties, this study revealed that granules from these qualities were more poor flowing than the corresponding powder blends, which was not seen for granules from traditional qualities. The QbD approach used in this study could be extended beyond fillers. Thus any new compound/ingredient would first be characterized and then suitable formulation characteristics could be determined in silico, without running any additional experiments.

  12. The Effect Size Statistic: Overview of Various Choices.

    ERIC Educational Resources Information Center

    Mahadevan, Lakshmi

    Over the years, methodologists have been recommending that researchers use magnitude of effect estimates in result interpretation to highlight the distinction between statistical and practical significance (cf. R. Kirk, 1996). A magnitude of effect statistic (i.e., effect size) tells to what degree the dependent variable can be controlled,…

  13. Effects of Ultra-Clean and centrifugal filtration on rolling-element bearing life

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.; Moyer, D. W.; Needelman, W. M.

    1981-01-01

    Fatigue tests were conducted on groups of 65-millimeter bore diameter deep-groove ball bearings in a MIL-L-23699 lubricant under two levels of filtration. In one test series, the oil cleanliness was maintained at an exceptionally high level (better than a class "000" per NAS 1638) with a 3 micron absolute barrier filter. These tests were intended to determine the "upper limit" in bearing life under the strictest possible lubricant cleanliness conditions. In the tests using a centrifugal oil filter, contaminants of the type found in aircraft engine filters were injected into the filters' supply line at 125 milligrams per bearing-hour. "Ultra-clean" lubrication produced bearing fatigue lives that were approximately twice that obtained in previous tests with contaminated oil using 3 micron absolute filtration and approximately three times that obtained with 49 micron filtration. It was also observed that the centrifugal oil filter had approximately the same effectiveness as a 30 micron absolute filter in preventing bearing surface damage.

  14. Inherent size effects on XANES of nanometer metal clusters: Size-selected platinum clusters on silica

    SciTech Connect

    Dai, Yang; Gorey, Timothy J.; Anderson, Scott L.; Lee, Sungsik; Lee, Sungwon; Seifert, Soenke; Winans, Randall E.

    2016-12-12

    X-ray absorption near-edge structure (XANES) is commonly used to probe the oxidation state of metal-containing nanomaterials, however, as the particle size in the material drops below a few nanometers, it becomes important to consider inherent size effects on the electronic structure of the materials. In this paper, we analyze a series of size-selected Ptn/SiO2 samples, using X-ray photoelectron spectroscopy (XPS), low energy ion scattering, grazing-incidence small angle X-ray scattering, and XANES. The oxidation state and morphology are characterized both as-deposited in UHV, and after air/O2 exposure and annealing in H2. Here, the clusters are found to be stable during deposition and upon air exposure, but sinter if heated above ~150 °C. XANES shows shifts in the Pt L3 edge, relative to bulk Pt, that increase with decreasing cluster size, and the cluster samples show high white line intensity. Reference to bulk standards would suggest that the clusters are oxidized, however, XPS shows that they are not. Instead, the XANES effects are attributable to development of a band gap and localization of empty state wavefunctions in small clusters.

  15. Inherent size effects on XANES of nanometer metal clusters: Size-selected platinum clusters on silica

    DOE PAGES

    Dai, Yang; Gorey, Timothy J.; Anderson, Scott L.; ...

    2016-12-12

    X-ray absorption near-edge structure (XANES) is commonly used to probe the oxidation state of metal-containing nanomaterials, however, as the particle size in the material drops below a few nanometers, it becomes important to consider inherent size effects on the electronic structure of the materials. In this paper, we analyze a series of size-selected Ptn/SiO2 samples, using X-ray photoelectron spectroscopy (XPS), low energy ion scattering, grazing-incidence small angle X-ray scattering, and XANES. The oxidation state and morphology are characterized both as-deposited in UHV, and after air/O2 exposure and annealing in H2. Here, the clusters are found to be stable during depositionmore » and upon air exposure, but sinter if heated above ~150 °C. XANES shows shifts in the Pt L3 edge, relative to bulk Pt, that increase with decreasing cluster size, and the cluster samples show high white line intensity. Reference to bulk standards would suggest that the clusters are oxidized, however, XPS shows that they are not. Instead, the XANES effects are attributable to development of a band gap and localization of empty state wavefunctions in small clusters.« less

  16. Rolling stones and turbulent eddies: why the bigger live longer and travel farther

    PubMed Central

    Bejan, Adrian

    2016-01-01

    Here we report the discovery that even the simplest, oldest and most prevalent forms of evolutionary movement—rolling bodies and whirls of turbulence—exhibit the same body-size effect on life time and life travel as the evolutionary movement united by the body-size effect so far: animals, rivers, vehicles, jets and plumes. In short, the bigger should last longer and travel farther. For rolling bodies, the life span (t) and the life travel (L) should increase with the body mass (M) raised to the powers 1/6 and 1/3, respectively. The number of rolls during this movement is constant, independent of body size. For an eddy of turbulence, t should increase with the eddy mass (M) raised to the power 2/3, while L should increase with M2/3 times the bulk speed of the turbulent stream that carries the eddy. The number of rolls during the eddy life span is a constant independent of eddy size. PMID:26883787

  17. Size Effects in the Catalytic Activity of Unsupported Metallic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Weber, Alfred P.; Seipenbusch, Martin; Kasper, Gerhard

    2003-08-01

    The influence of the size of nanoparticles on their catalytic activity was investigated for two systems on unsupported, i.e. gasborne nanoparticles. For the oxidation of hydrogen on Pt nanoparticle agglomerates, transport processes had to be taken into account to extract the real nanoparticle size effects. The results indicate an optimum particle size for the catalytic activity below 5nm which points clearly toward a real volume effect. In the case of the methanation reaction on gasborne Ni nanoparticles, no transport limitations were observed and the product concentration was directly proportional to the activity of the primary particles. We found an activity maximum for particles of about 19nm in diameter. This size is too large to be attributed to a real nanoparticle size effect induced by the electronic band structure. Therefore, we concluded that the particle size influences the adsorption behavior of the carbon monoxide molecules. In fact, it is known that intermediate adsorption enthalpies may favor dissociation processes, which is an essential step for the reaction, as manifested in the so called volcano-shaped curve. Then, in addition to the material dependence of the adsorption, we would also encounter a direct size dependence in the case of methanation on gasborne Ni nanoparticles.

  18. Finite size effects on the QCD spectrum revisited

    SciTech Connect

    Gottlieb, S. . Dept. of Physics Brookhaven National Lab., Upton, NY )

    1992-01-01

    We have continued our study of finite size effects in the QCD spectrum on lattices ranging in size from 8[sup 3][times]24 to 16[sup 3][times]24. We have increased our statistics for quark mass am[sub q]=0.025 for the smallest lattice size. In addition, we have studied quark mass 0.01225 for lattice sizes 12[sup 3][times]24. These lattice sizes correspond to a box 1.8-3.6 fm on a side when the rho mass at zero quark mass is used to set the scale. We discuss the nucleon to rho mass ratio at a smaller value of m[pi]/m[rho] than previously studied with two dynamical flavors.

  19. Finite size effects on the QCD spectrum revisited

    SciTech Connect

    Gottlieb, S. |; MIMD Lattice Calculation Collaboration

    1992-12-31

    We have continued our study of finite size effects in the QCD spectrum on lattices ranging in size from 8{sup 3}{times}24 to 16{sup 3}{times}24. We have increased our statistics for quark mass am{sub q}=0.025 for the smallest lattice size. In addition, we have studied quark mass 0.01225 for lattice sizes 12{sup 3}{times}24. These lattice sizes correspond to a box 1.8-3.6 fm on a side when the rho mass at zero quark mass is used to set the scale. We discuss the nucleon to rho mass ratio at a smaller value of m{pi}/m{rho} than previously studied with two dynamical flavors.

  20. Enhanced oxidation resistance of active nanostructures via dynamic size effect

    NASA Astrophysics Data System (ADS)

    Liu, Yun; Yang, Fan; Zhang, Yi; Xiao, Jianping; Yu, Liang; Liu, Qingfei; Ning, Yanxiao; Zhou, Zhiwen; Chen, Hao; Huang, Wugen; Liu, Ping; Bao, Xinhe

    2017-02-01

    A major challenge limiting the practical applications of nanomaterials is that the activities of nanostructures (NSs) increase with reduced size, often sacrificing their stability in the chemical environment. Under oxidative conditions, NSs with smaller sizes and higher defect densities are commonly expected to oxidize more easily, since high-concentration defects can facilitate oxidation by enhancing the reactivity with O2 and providing a fast channel for oxygen incorporation. Here, using FeO NSs as an example, we show to the contrary, that reducing the size of active NSs can drastically increase their oxidation resistance. A maximum oxidation resistance is found for FeO NSs with dimensions below 3.2 nm. Rather than being determined by the structure or electronic properties of active sites, the enhanced oxidation resistance originates from the size-dependent structural dynamics of FeO NSs in O2. We find this dynamic size effect to govern the chemical properties of active NSs.

  1. Direct laser interference patterning of metallic sleeves for roll-to-roll hot embossing

    NASA Astrophysics Data System (ADS)

    Lang, Valentin; Rank, Andreas; Lasagni, Andrés. F.

    2017-03-01

    Surfaces equipped with periodic patterns with feature sizes in the micrometer, submicrometer and nanometer range present outstanding surface properties. Many of these surfaces can be found on different plants and animals. However, there are few methods capable to produce such patterns in a one-step process on relevant technological materials. Direct laser interference patterning (DLIP) provides both high resolution as well as high throughput. Recently, fabrication rates up to 1 m2·min-1 could be achieved. However, resolution was limited to a few micrometers due to typical thermal effects that arise when nanosecond pulsed laser systems are used. Therefore, this study introduces an alternative to ns-DLIP for the fabrication of multi-scaled micrometer and submicrometer structures on nickel surfaces using picosecond pulses (10 ps at a wavelength of 1064 nm). Due to the nature of the interaction process of the metallic surfaces with the ultrashort laser pulses, it was not only possible to directly transfer the shape of the interference pattern intensity distribution to the material (with spatial periods ranging from 1.5 μm to 5.7 μm), but also to selectively obtain laser induce periodic surface structures with feature sizes in the submicrometer and nanometer range. Finally, the structured nickel sleeves are utilized in a roll-to-roll hot embossing unit for structuring of polymer foils. Processing speeds up to 25 m·min-1 are reported.

  2. Effect of stimulus check size on multifocal visual evoked potentials.

    PubMed

    Balachandran, Chandra; Klistorner, Alexander I; Graham, Stuart L

    2003-03-01

    In this study we examined the effects of varying stimulus check size on multifocal visual evoked potential (VEP). We also evaluated the currently used cortical scaling of stimulus segments. The ObjectiVision multifocal objective perimeter stimulates the eye with random check patterns at 56 cortically scaled segments within the visual field extending to a radius of 26 degrees. All cortically scaled segments have equal number of checks, which gradually increase in size from the center to the periphery, proportional to the size of the segment. Stimuli with 9, 16, 25, 36 and 49 checks/segment were tested on 10 eyes belonging to 10 normal subjects. The check size varied inversely with number of checks per segment. VEP was recorded using bipolar occipital cross electrodes (7 min/eye), the amplitude and latency of responses obtained were compared with the check size at different eccentricities. Our findings suggest that the existing setting with 16 checks/segment subtending 26' to 140' from center to periphery, is the most effective amongst all the check sizes. Decreasing the check size prolongs the latency in the central field only. Cortical scaling of segments generates responses of the same order of magnitude throughout the field, but could be improved slightly to enhance the signal from the outer two rings.

  3. Brazil-nut effect: Size separation of granular particles

    NASA Astrophysics Data System (ADS)

    Möbius, Matthias E.; Lauderdale, Benjamin E.; Nagel, Sidney R.; Jaeger, Heinrich M.

    2001-11-01

    Granular media differ from other materials in their response to stirring or jostling - unlike two-fluid systems, bi-disperse granular mixtures will separate according to particle size when shaken, with large particles rising, a phenomenon termed the 'Brazil-nut effect'. Mounting evidence indicates that differences in particle density affect size separation in mixtures of granular particles. We show here that this density dependence does not follow a steady trend but is non-monotonic and sensitive to background air pressure. Our results indicate that particle density and interstitial air must both be considered in size segregation.

  4. 'Slings' enable neutrophil rolling at high shear.

    PubMed

    Sundd, Prithu; Gutierrez, Edgar; Koltsova, Ekaterina K; Kuwano, Yoshihiro; Fukuda, Satoru; Pospieszalska, Maria K; Groisman, Alex; Ley, Klaus

    2012-08-16

    Most leukocytes can roll along the walls of venules at low shear stress (1 dyn cm−2), but neutrophils have the ability to roll at tenfold higher shear stress in microvessels in vivo. The mechanisms involved in this shear-resistant rolling are known to involve cell flattening and pulling of long membrane tethers at the rear. Here we show that these long tethers do not retract as postulated, but instead persist and appear as 'slings' at the front of rolling cells. We demonstrate slings in a model of acute inflammation in vivo and on P-selectin in vitro, where P-selectin-glycoprotein-ligand-1 (PSGL-1) is found in discrete sticky patches whereas LFA-1 is expressed over the entire length on slings. As neutrophils roll forward, slings wrap around the rolling cells and undergo a step-wise peeling from the P-selectin substrate enabled by the failure of PSGL-1 patches under hydrodynamic forces. The 'step-wise peeling of slings' is distinct from the 'pulling of tethers' reported previously. Each sling effectively lays out a cell-autonomous adhesive substrate in front of neutrophils rolling at high shear stress during inflammation.

  5. A new criterion for predicting rolling-element fatigue lives of through-hardened steels

    NASA Technical Reports Server (NTRS)

    Chevalier, J. L.; Zaretsky, E. V.; Parker, R. J.

    1972-01-01

    A carbide factor was derived based upon a statistical analysis which related rolling-element fatigue life to the total number of residual carbide particles per unit area, median residual carbide size, and percent residual carbide area. An equation was experimentally determined which predicts material hardness as a function of temperature. The limiting temperatures of all of the materials studied were dependent on initial room temperature hardness and tempering temperature. An equation was derived combining the effects of material hardness, carbide factor, and bearing temperature to predict rolling-element bearing life.

  6. A new criterion for predicting rolling-element fatigue lives of through-hardened steels.

    NASA Technical Reports Server (NTRS)

    Chevalier, J. L.; Zaretsky, E. V.; Parker, R. J.

    1972-01-01

    A carbide factor was derived based upon a statistical analysis which related rolling-element fatigue life to the total number of residual carbide particles per unit area, median residual carbide size, and percent residual carbide area. An equation was empirically determined which predicts material hardness as a function of temperature. The limiting temperatures of all of the materials studied were dependent on initial room temperature hardness and tempering temperature. An equation was derived combining the effects of material hardness, carbide factor, and bearing temperature to predict rolling-element bearing life.

  7. Size and nonlinear optical effects of ferroic organic nanocomposites

    NASA Astrophysics Data System (ADS)

    Lakshminarayana, G.; Kapustianyk, V.; Ozga, K.; Rudyk, V.; Kityk, I. V.; Brik, M. G.; Berdowski, J.; Tylczynski, Z.

    2011-08-01

    The third harmonic generation of ferroic (NH2(C2H5)2)2CuCl4 diethylammonium cuprate chlorate (DEACC) single crystals and nanocrystals (NCs) incorporated into polymethyl methacrylate (PMMA) polymer matrices was investigated. It was established that the crystal field spectra of Cu2+ ion determines the observed size dependence effect. The role of nanocrystallite size and content and the symmetry of the THG at ambient and nitrogen temperatures were studied.

  8. Thermophoresis of microemulsion droplets: size dependence of the Soret effect.

    PubMed

    Vigolo, Daniele; Brambilla, Giovanni; Piazza, Roberto

    2007-04-01

    Thermophoresis, akin to thermal diffusion in simple fluid mixtures, consists of particle drift induced by a temperature gradient. Notwithstanding its practical interest, the dependence of thermophoretic effects on particle size R is still theoretically and experimentally debated. By performing measurements of water-in-oil microemulsion droplets with tunable size, we show that the thermal diffusion coefficient, at least for a suspension of small particles in a nonpolar solvent, does not appreciably depend on R .

  9. Effect of alpha quenching on magnetic field size.

    PubMed

    Núñez, M

    2001-05-01

    It is commonly assumed that the alpha effect of mean-field magnetohydrodynamics essentially stops acting wherever the mean-field size reaches a certain value. We show that if the mean velocity is approximately constant, the regions where the field reaches such a threshold tend to shrink in size or the field tends to become constant there. The rate of this process is also estimated.

  10. The effect of habitat patch size on small mammal populations

    Treesearch

    Mark D. Yates; Susan C. Loeb; David C. Guynn

    1997-01-01

    Habitat fragmentation is one of the greatest threats to the conservation of bio­diversity and has 3 components: habitat loss, patch isolation, and patch size. The authors tested the effects of forest-clearing size on small mammal populations in the Upper Coastal Plain of South Carolina. These clearings act as islands for many species of small mam­mals, particularly old...

  11. A multiscale gradient-dependent plasticity model for size effects

    NASA Astrophysics Data System (ADS)

    Lyu, Hao; Taheri-Nassaj, Nasrin; Zbib, Hussein M.

    2016-06-01

    The mechanical behaviour of polycrystalline material is closely correlated to grain size. In this study, we investigate the size-dependent phenomenon in multi-phase steels using a continuum dislocation dynamic model coupled with viscoplastic self-consistent model. We developed a dislocation-based strain gradient plasticity model and a stress gradient plasticity model, as well as a combined model, resulting in a theory that can predict size effect over a wide range of length scales. Results show that strain gradient plasticity and stress gradient plasticity are complementary rather than competing theories. The stress gradient model is dominant at the initial strain stage, and is much more effective for predicting yield strength than the strain gradient model. For larger deformations, the strain gradient model is dominant and more effective for predicting size-dependent hardening. The numerical results are compared with experimental data and it is found that they have the same trend for the yield stress. Furthermore, the effect of dislocation density at different strain stages is investigated, and the findings show that the Hall-Petch relation holds for the initial strain stage and breaks down for higher strain levels. Finally, a power law to describe the size effect and the transition zone between the strain gradient and stress gradient dominated regions is developed.

  12. Statistical power and effect sizes of clinical neuropsychology research.

    PubMed

    Bezeau, S; Graves, R

    2001-06-01

    Cohen, in a now classic paper on statistical power, reviewed articles in the 1960 issue of one psychology journal and determined that the majority of studies had less than a 50-50 chance of detecting an effect that truly exists in the population, and thus of obtaining statistically significant results. Such low statistical power, Cohen concluded, was largely due to inadequate sample sizes. Subsequent reviews of research published in other experimental psychology journals found similar results. We provide a statistical power analysis of clinical neuropsychological research by reviewing a representative sample of 66 articles from the Journal of Clinical and Experimental Neuropsychology, the Journal of the International Neuropsychology Society, and Neuropsychology. The results show inadequate power, similar to that for experimental research, when Cohen's criterion for effect size is used. However, the results are encouraging in also showing that the field of clinical neuropsychology deals with larger effect sizes than are usually observed in experimental psychology and that the reviewed clinical neuropsychology research does have adequate power to detect these larger effect sizes. This review also reveals a prevailing failure to heed Cohen's recommendations that researchers should routinely report a priori power analyses, effect sizes and confidence intervals, and conduct fewer statistical tests.

  13. The Relationship of Class Size Effects and Teacher Salary

    ERIC Educational Resources Information Center

    Peevely, Gary; Hedges, Larry; Nye, Barbara A.

    2005-01-01

    The effects of class size on academic achievement have been studied for decades. Although the results of small-scale, randomized experiments and large-scale, econometric studies point to positive effects of small classes, some scholars see the evidence as ambiguous. Recent analyses from a 4-year, large-scale, randomized experiment on the effects…

  14. Effects of Class Size on Alternative Educational Outcomes across Disciplines

    ERIC Educational Resources Information Center

    Cheng, Dorothy A.

    2011-01-01

    This is the first study to use self-reported ratings of student learning, instructor recommendations, and course recommendations as the outcome measure to estimate class size effects, doing so across 24 disciplines. Fixed-effects models controlling for heterogeneous courses and instructors reveal that increasing enrollment has negative and…

  15. Size-effect of explosive sensitivity under low velocity impact

    NASA Astrophysics Data System (ADS)

    Ma, Danzhu; Chen, Pengwan; Zhou, Qiang

    2013-06-01

    Low velocity impact may ignite the solid high explosives and cause undesired explosion incidents. The safety of high explosives under low velocity impact is one of the most important problems in handling, manufacture, storage, and transportation procedures. More and more evaluation tests have been developed for low velocity impact scenarios, including, but not limited to the drop hammer impact test, the Susan test, the Spigot test, and the Steven test, with a charge mass varying from tens of milligrams to several kilograms. The effects of specimen size on explosive sensitivity were found in our drop hammer impact test and Steven tests, including the threshold velocity/height and reaction violence. To further analyze the size effects on explosive sensitivity under low velocity impacts, we collected the impact sensitivity data of several PBX explosives in the drop hammer test, the Steven test, the Susan test and the Spigot test. The effective volume of explosive charge and the threshold specific mechanical energy were introduced to investigate the size-effect on the explosive ignition thresholds. The effective volumes of explosive charge in Steven test and Spigot test were obtained by numerical simulation, due to the localization of the impact. The threshold specific mechanical energy is closely related to the effective volume of explosive charge. The results show that, with the increase of effective volume, the specific mechanical energy needed for explosive ignition decreases and trends to reach a constant value. The mechanisms of size effects on explosive sensitivity are also discussed.

  16. Specimen size effect of explosive sensitivity under low velocity impact

    NASA Astrophysics Data System (ADS)

    Ma, Danzhu; Chen, Pengwan; Dai, Kaida; Zhou, Qiang

    2014-05-01

    Low velocity impact may ignite the solid high explosives and cause undesired explosion incidents. The safety of high explosives under low velocity impact is one of the most important issues in handling, manufacture, storage, and transportation procedures. Various evaluation tests have been developed for low velocity impact scenarios, including, but not limited to the drop hammer test, the Susan test, the Spigot test, and the Steven test, with a charge mass varying from tens of milligrams to several kilograms. The effects of specimen size on explosive sensitivity were found in some impact tests such as drop hammer test and Steven tests, including the threshold velocity/height and reaction violence. To analyse the specimen size effects on explosive sensitivity under low velocity impacts, we collected the impact sensitivity data of several PBX explosives in the drop hammer test, the Steven test, the Susan test and the Spigot test. The effective volume of explosive charge and the critical specific mechanical energy were introduced to investigate the size-effect on the explosive reaction thresholds. The effective volumes of explosive charge in Steven test and Spigot test were obtained by numerical simulation, due to the deformation localization of the impact loading. The critical specific mechanical energy is closely related to the effective volume of explosive charge. The results show that, with the increase of effective volume, the critical mechanical energy needed for explosive ignition decreases and tends to reach a constant value. The mechanisms of size effects on explosive sensitivity are also discussed.

  17. The effects of group selection harvest size on logging productivity

    Treesearch

    Curt C. Hassler; Shawn T. Grushecky; Chris B. LeDoux

    2000-01-01

    Because increasing demands are being placed on industry to harvest timber by aesthetically, economically, and ecologically acceptable means, we investigated the effects of a ground-based group selection harvest on logging productivity. Results show that size of opening had little or no effect on skidding productivity. However, significant skidder operator differences...

  18. Statistical Power and Effect Size in Social Education Research.

    ERIC Educational Resources Information Center

    VanSickle, Ronald L.

    1983-01-01

    Tests of statistical significance are insufficient for generating sufficient grounds to infer the presence or absence of a phenomenon. To avoid misuse of observed statistical significance levels as measures of scientific and practical importance, effect size can be used to interpret the meaning of effects. (Author/RM)

  19. Effects of Class Size on Alternative Educational Outcomes across Disciplines

    ERIC Educational Resources Information Center

    Cheng, Dorothy A.

    2011-01-01

    This is the first study to use self-reported ratings of student learning, instructor recommendations, and course recommendations as the outcome measure to estimate class size effects, doing so across 24 disciplines. Fixed-effects models controlling for heterogeneous courses and instructors reveal that increasing enrollment has negative and…

  20. Nanometer size field effect transistors for terahertz detectors.

    PubMed

    Knap, W; Rumyantsev, S; Vitiello, M S; Coquillat, D; Blin, S; Dyakonova, N; Shur, M; Teppe, F; Tredicucci, A; Nagatsuma, T

    2013-05-31

    Nanometer size field effect transistors can operate as efficient resonant or broadband terahertz detectors, mixers, phase shifters and frequency multipliers at frequencies far beyond their fundamental cut-off frequency. This work is an overview of some recent results concerning the application of nanometer scale field effect transistors for the detection of terahertz radiation.