Journal articles: 'Sheep shearers'

1

Monsell, F. P., and R. M. Tillman. "Shearer's wrist: the carpal tunnel syndrome as an occupational disease in professional sheep shearers." Occupational and Environmental Medicine 49, no. 8 (August 1, 1992): 594–95. http://dx.doi.org/10.1136/oem.49.8.594.

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de Jongh, Michael, and Riana Steyn. "Itinerancy as a way of life: The nomadic sheep‐shearers of the South African Karoo." Development Southern Africa 11, no. 2 (May 1994): 217–28. http://dx.doi.org/10.1080/03768359408439744.

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Woodruff, Madeleine Eloise, Rebecca Doyle, Grahame Coleman, Lauren Hemsworth, and Carolina Munoz. "Knowledge and attitudes are important factors in farmers’ choice of lamb tail docking length." Veterinary Record 186, no. 10 (January 20, 2020): 319. http://dx.doi.org/10.1136/vr.105631.

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BackgroundTail docking is common practice in the sheep industry to prevent soiling of the breech and flystrike. To ensure optimal healing after tail docking and reduce the risk of arthritis, perineal cancers and prolapses, it is recommended to dock tails equivalent to the length of the vulva. However, recent studies have found that some tails are docked too short (24–86 per cent).MethodsTo address this issue, this study aimed to identify key drivers behind tail docking length decisions. Two focus groups, phone (n=30) and online surveys (n=21) were conducted in regional Victoria, Australia to examine farmer knowledge of and attitudes towards appropriate lamb tail length and barriers to best practice. The focus group data were analysed qualitatively, and the surveys were analysed qualitatively and quantitatively.ResultsIn total, 57 per cent of farmers were classed as docking tails short. Short tail docking appeared to be influenced by unawareness of the recommended length and docking at a length that shearers approve of. Other potential factors included lack of knowledge of negative health consequences associated with short tails, importance placed on dag and flystrike prevention, and impracticality of measuring where to dock.ConclusionAddressing these factors in future education and intervention programmes may improve tail docking practice and sheep welfare.

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Gregory, Diane E., Stephan Milosavljevic, and Jack P. Callaghan. "Quantifying low back peak and cumulative loads in open and senior sheep shearers in New Zealand: Examining the effects of a trunk harness." Ergonomics 49, no. 10 (August 2006): 968–81. http://dx.doi.org/10.1080/00140130600576785.

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LIVEWELL, DAVID. "SHEET METAL SHEARS." Yale Review 93, no. 3 (July 2005): 59. http://dx.doi.org/10.1111/j.0044-0124.2005.00932.x.

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Williams, C. R. P. "Acute Calcification of the Peroneal Tendons in a Sheep Shearer." Foot & Ankle International 17, no. 1 (January 1996): 49–50. http://dx.doi.org/10.1177/107110079601700111.

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Acute calcification of periarticular tendons is known to occur at a variety of sites after subclinical trauma or after chronic overuse injuries. It can also be due to degeneration of the affected tendon. This problem is reported in the peroneal tendons of a sheep shearer.

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7

Abe, Yohei, Ken Ichiro Mori, Shigehiro Nakanoshita, and Purwo Kadarno. "Direct Punching in Inclined Ultra-High Strength Steel Sheets." Key Engineering Materials 622-623 (September 2014): 1051–57. http://dx.doi.org/10.4028/www.scientific.net/kem.622-623.1051.

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A direct punching of inclined ultra-high strength steel sheets having low ductility was carried out to improve the quality of the sheared edge. In the direct punching of an inclined sheet, the contact between the sheet and punch became gradual because of touch from the bottom edge of the punch, and thus the sheared portion tended to bend in the latter half of punching. As the strength of the sheet increased, defects such as burr and secondary burnished surface were occurred around the sheared edge due to the low ductility. The range of direct punching for sheared edge without defects was shown for the high strength steel sheets. To prevent the occurrence of defects, a punch having inclined bottom was used. In this punch, the contact with the sheet was changed, the uniform contact with the inclined bottom was given. In the punch having the inclined bottom, the secondary burnished surface in the edge of 980 MPa grade steel sheet was prevented.

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Drozdov, Anatoly. "Simulate the single-throw electric upcut shears operation in Mathcad." E3S Web of Conferences 281 (2021): 01022. http://dx.doi.org/10.1051/e3sconf/202128101022.

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The relevance of sheet processing technology, which finds increasing application, is given. Efficient equipment for sheet metal processing and sheet mounting is justified and proposed. This article deals with upcut shears’ operation. The solution to the mathematic model of manual upcut shears using Mathcad is provided.

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Vaiude, P., M. Dhital, and K. Hancock. "A true pilonidal sinus in the hand of a sheep shearer." Journal of Surgical Case Reports 2011, no. 12 (December 2011): 6. http://dx.doi.org/10.1093/jscr/2011.12.6.

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Ugai, M. "The structure and dynamics of a large-scale plasmoid generated by fast reconnection in the geomagnetic tail." Annales Geophysicae 29, no. 1 (January 13, 2011): 147–56. http://dx.doi.org/10.5194/angeo-29-147-2011.

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Abstract. As a sequence of Ugai (2010b), the present paper studies in detail the structure and dynamics of large-scale (principal) plasmoid, generated by the fast reconnection evolution in a sheared current sheet with no initial northward field component. The overall plasmoid domain is divided into the plasmoid reconnection region P and the plasmoid core region C. In the region P, the magnetized plasma with reconnected field lines are accumulated, whereas in the region C, the plasma, which was intially embedded in the current sheet and has been ejected away by the reconnection jet, is compressed and accumulated. In the presence of the sheared magnetic field in the east-west direction in the current sheet, the upper and lower parts of the reconnection region P are inversely shifted in the east-west directions. Accordingly, the plasmoid core region C with the accumulated sheared field lines is bent in the north-south direction just ahead of the plasmoid center x=XC, causing the magnetic field component in the north-south direction, whose sign is always opposite to that of the reconnected field lines. Therefore, independently of the sign of the initial sheared field, the magnetic field component Bz in the north-south direction has the definite bipolar profile around XC along the x-axis. At x=XC, the sheared field component has the peak value, and as the sheared fields accumulated in the region C become larger, the bipolar field profile becomes more distinct.

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11

Mahajan, S. M., and R. D. Hazeltine. "Sheared-flow generalization of the Harris sheet." Physics of Plasmas 7, no. 4 (April 2000): 1287–93. http://dx.doi.org/10.1063/1.873939.

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12

Han, Soo Sik. "Study for Sheared Edge Quality of High Strength Steel Sheet." Key Engineering Materials 626 (August 2014): 252–57. http://dx.doi.org/10.4028/www.scientific.net/kem.626.252.

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The empirical approach was adopted to investigate the process parameters that effect on the quality of high strength steel sheet sheared edge. As a result of study, the quality of sheared edge that can be represented as the ratio of the shiny burnished surface to the sheared surface was not under influence of die clearance, lubrication and cutting line direction but under influence of the material strength and the usage of lower pad. The roll-over and burr height is highly affected by the die clearance and the usage of lower pad. The lower pad underneath of blank is of help to reduce the amount of roll-over and burr even at large die clearance.

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13

CHUNG, WAN-JIN, KU-BOK HWANG, JONG-HO KIM, and HO-YEUN RYU. "A STUDY ON THE IMPROVEMENT OF THE ACCURACY OF A SHAVING PROCESS USING A PROGRESSIVE DIE." International Journal of Modern Physics B 22, no. 31n32 (December 30, 2008): 5673–79. http://dx.doi.org/10.1142/s0217979208050991.

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Shaving is widely used as a finish process to generate a smooth sheared surface from a sheared surface originally obtained by blanking or piercing. In the sheet metal forming industry, progressive operations are commonly used to increase productivity. However, it is difficult to utilize shaving in a progressive die because a blank is dropped down after blanking. In this study, a method that addresses this issue is introduced, and the two-stage progressive operation of half-blanking and blank-shaving is suggested. For this study, a square part made by blanking and piercing is considered, and a progressive die that includes piercing, pierce-shaving, half-blanking and blank-shaving is prepared for a specimen of cold rolled steel sheet. Experiments are carried out involving the process parameters of the shaving allowance, shaving clearance and the half-blanking penetration depth. It was found that the proposed method using a progressive die offers a completely smooth sheared surface along with feasible working conditions for a cold rolled steel sheet with a thickness of 1.56 mm.

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Hsu, Yuan Chuan, and Tung Sheng Yang. "A Predictive Model Construction for the Sheared Planes in Sheet Metal Shearing Process." Key Engineering Materials 364-366 (December 2007): 590–94. http://dx.doi.org/10.4028/www.scientific.net/kem.364-366.590.

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The shearing processes such as the blanking and piercing of sheet metals have been often used to prepare workpiece for subsequent forming operation. The sheared plane plays an important role in the shearing products’ dimension precision and their functions. The quality of sheared plane is affected not only by the material characteristics but also by the process parameters. In the current study, the finite element method is used to investigate the shearing process of sheet metals. Then, the neural network was employed to construct the relationship model of shearing process parameters related to the fracture depth of sheared plane, such as blank holding force, die corner radius, punch-die clearance, friction factor and punch speed,. The result and approach obtained from this study would be beneficial to stamping industries because they provide the reference for the prediction of shearing process.

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15

Nagasawa, Shigeru, Yuuya Masaki, Yasushi Fukuzawa, and Yoshiharu Mutoh. "Bending Effect on Cutting Characteristics of Polycarbonate Thick Sheet Subjected to Indentation of Heightwise-Asymmetric Wedge Blades." Advanced Materials Research 445 (January 2012): 68–72. http://dx.doi.org/10.4028/www.scientific.net/amr.445.68.

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This paper describes for verification of bending effect on the performance of the heightwise-asymmetric plunge cutting method, which was composed of an upper-wedge blade and a lower-wedge blade embedded in the lower-counter plate, in order to apply this cutting method for a polycarbonate (PC) thick sheet. By varying the tip angle αU and the tip thickness wU of lower blade embedded in the counter plate, and combining a standard steel cutting rule of 42° center bevel blade, the sheared profile of two kinds of PC worksheet (the thickness of which was chosen as t=0.5, 1.0 mm) was experimentally investigated. Through this experiment, it was found that the sheared profile (the necked height ηn, the upper inclination angle β, the lower inclination angle βU) of PC worksheet was primarily characterized by the normalized lower tip thickness wU/t. The difference of sheared profile was explained using the Prandtls punching solution for two kinds of PC worksheet. Furthermore, by varying the heightwise position of lower blade tip, the bending effect on sheared profile of worked sheet was experimentally verified.

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16

Hurricane, Omar A. "MHD ballooning stability of a sheared plasma sheet." Journal of Geophysical Research: Space Physics 102, A9 (September 1, 1997): 19903–11. http://dx.doi.org/10.1029/97ja01595.

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17

Smyth, W. D., and S. Kimura. "Mixing in a Moderately Sheared Salt-Fingering Layer." Journal of Physical Oceanography 41, no. 7 (July 1, 2011): 1364–84. http://dx.doi.org/10.1175/2010jpo4611.1.

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Abstract Mixing due to sheared salt fingers is studied by means of direct numerical simulations (DNS) of a double-diffusively unstable shear layer. The focus is on the “moderate shear” case, where shear is strong enough to produce Kelvin–Helmholtz (KH) instability but not strong enough to produce the subharmonic pairing instability. This flow supports both KH and salt-sheet instabilities, and the objective is to see how the two mechanisms work together to flux heat, salt, and momentum across the layer. For observed values of the bulk Richardson number Ri and the density ratio Rρ, the linear growth rates of KH and salt-sheet instabilities are similar. These mechanisms, as well as their associated secondary instabilities, lead the flow to a fully turbulent state. Depending on the values of Ri and Rρ, the resulting turbulence may be driven mainly by shear or mainly by salt fingering. Turbulent mixing causes the profiles of temperature, salinity, and velocity to spread; however, in salt-sheet-dominated cases, the net density (or buoyancy) layer thins over time. This could be a factor in the maintenance of the staircase and is also an argument in favor of an eventual role for Holmboe instability. Fluxes are scaled using both laboratory scalings for a thin layer and an effective diffusivity. Fluxes are generally stronger in salt-sheet-dominated cases. Shear instability disrupts salt-sheet fluxes while adding little flux of its own. Shear therefore reduces mixing, despite providing an additional energy source. The dissipation ratio Γ is near 0.2 for shear-dominated cases but is much larger when salt sheets are dominant, supporting the use of Γ in the diagnosis of observed mixing phenomena. The profiler approximation Γz, however, appears to significantly overestimate the true dissipation ratio.

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Chaijit, Seksan, and Shigeru Nagasawa. "Effect of Underlay Rigidity on Breaking Behavior of Aluminum Sheet during Wedged Shearing Process." Applied Mechanics and Materials 117-119 (October 2011): 1693–700. http://dx.doi.org/10.4028/www.scientific.net/amm.117-119.1693.

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This study aims to clarify the breaking behavior during wedge shearing process of an aluminum worksheet that stacked on to an underlay sheet. One of the problems faced in wedge cutting process is the separation possibility and the quality sheared profile of worksheet, the lower underlay sheet was introduced. To study the breaking behavior of an aluminum sheet with flexible underlays, a 42°center bevel blade indentation test to a 0.39mm thickness aluminum stacked on to several flexible underlays conditions were carried out experimentally and numerically. For discussing the effect of the rigidity of underlay on the breaking behavior of worksheet, an elasto-plastic finite element analysis was applied to. The following were obtained: (i) the initial breaking of worksheet and the sheared profile depends on the underlay rigidity; (ii) the breaking propagation is started from the lower surface of worksheet and grows up to the upper side beneath the tip edge.

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19

Yamashita, Minoru, Tatsuya Tezuka, and Toshio Hattori. "Joining Experiment of Aluminum Sheets Using High-Speed Shearing." Applied Mechanics and Materials 566 (June 2014): 379–84. http://dx.doi.org/10.4028/www.scientific.net/amm.566.379.

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A novel method for joining of sheet edges was investigated. It makes use of the sheared faces under high-speed. The temperature remarkably elevates and the material softens in the thin severely deformed layer. The cut faces are contacted each other with sliding motion immediately after shearing. Sheet materials are a pure aluminum A1050 and its alloy A5052. Two similar sets of circular shearing punch, die and sheet are concentrically stacked in the device for performing the simultaneous shearing. The upper sheared circular sheet slides into the hole of the lower one for joining shortly after the shearing. Strain-rate order was about 104/s in shearing, where the punches were driven by a drop-weight. Quasi-static test was also conducted for comparison. Joining was achieved only in the high-speed test. Joining boundary was not visible at the central portion in thickness, though the gap openings were seen near both sheet surfaces. Joining efficiency was evaluated as the relative strength to the tensile strength of the material. It was improved as the shearing clearance becomes smaller. The maximum efficiency was about 30 % for A1050 material. It is about 25 % for A5052. It was at most 10 % in the joining of A1050 and A5052.

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20

Spišák, Emil, Janka Majerníková, and Emília Spišáková. "The Influence of Punch-Die Clearance on Blanked Edge Quality in Fine Blanking of Automotive Sheets." Materials Science Forum 818 (May 2015): 264–67. http://dx.doi.org/10.4028/www.scientific.net/msf.818.264.

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Fine blanking is a widely used process that permits the production of precise finished components which are cleanly sheared through the whole cutting surface. It can be eliminated secondary operations, such as milling, grinding, etc. Many studies on the weight reduction of automobile for fuel saving were underway. The clearance of the punch-die of a fine blanking tool is an important design factor that affects the sheared surface of a product. If the clearance is too big, a fractured surface would occur in the product while if it is too small, bulging would occur. The main objective of this paper is to provide an overview of the effect of clearance between punch and die in a fine blanking tool on quality of sheared surface. A well as to specify the effect of mechanical properties of sheared steel sheet on blanked edge quality given by ratio of hv/a0.

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21

Mitsomwang, Pusit, Rattana Borrisutthekul, Usanee Kitkamthorn, and Shigeru Nagasawa. "Investigation of Strain Hardening in Aluminum Alloy Sheared Sheet Based on Microhardness Measurement and FEM Analysis." International Journal of Automation Technology 12, no. 5 (September 5, 2018): 714–22. http://dx.doi.org/10.20965/ijat.2018.p0714.

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This research was carried out to investigate the strain hardening in an aluminum alloy worksheet caused by punch/die shearing by means of microhardness measurement and finite element method (FEM) analysis. To examine the strain-hardened zone at the sheared edge of a worksheet, a 0.36 mm thick AA4047 aluminum alloy cut by punch/die shearing was subjected to microhardness measurements. In addition, a two-dimensional FEM model was developed and used to simulate the shear cutting of the aluminum alloy worksheet. The fundamental shear cutting parameters, punch/die clearance, cutting tool wear, and friction at the worksheet/tool interfaces were numerically varied and simulated. From the investigation results, the strain-hardened zone was observed by hardness measurement. The size of the zone significantly varied under different cutting parameters. From the simulated stresses at the sheared zone, the variation of the width of the strain-hardened zone with respect to cutting parameters was determined by the maximum principal stress on the worksheet being sheared.

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22

Pilipenko, S. S., and A. P. Potapenkov. "Development and research of hydraulic drive of sheet shears." Izvestiya. Ferrous Metallurgy 62, no. 8 (September 13, 2019): 632–38. http://dx.doi.org/10.17073/0368-0797-2019-8-631-638.

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The paper describes the pump gear-multiplier drive of sheet shears with a two-cylinder power unit. The description of the developed drive scheme with the use of dual dispensers (reducer and multiplier) of periodic action is given. The gear is engaged at idle, the multiplier – at work. Their charging comes up at the reverse course of the power unit. Each dispenser has an input cylinder connected to the pump and two dosing (output) cylinders connected separately with the power cylinders of the power unit. In this case, the cylinder bodies form a fixed block, and the plungers (pistons) – a movable block. It solves the main task: synchronization of movement of the pistons (plungers) of the power cylinders during all operation periods. Due to different ratio of the area of pistons (plungers) of inlet (Fв ) and dosing cylinders (2Fд ), a direct stroke mode with two stages of pump speed and pressure is provided. For the reducer, ratio (Fв /(2Fд )) determines reduction coefficient (Kp < 1), for the multiplier – the coefficient of multiplication (Kм > 1). As a result, the idling speed of the pistons of the power cylinders and pressure developed by the pumps increase, and during the working stroke – these values decrease. Working pressure of the pumps is equalized at a direct flow at a reduced level, which determines reduction of their installation power (up to 30 %). The analysis of graphs of power loading and speed was made. The condition of constant load at each of three main periods of the drive operation was accepted as: idle, working and reverse. Determinant parameters of the considered drive are the coefficients Kр (reduction), Kм (animation) and Kс – the gain of the power unit. The paper presents a comparative analysis of the considered and simple pump drive in order to establish the received combination and range of these values.

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23

NISHIMURA, Ryuichi, Yasuhiro ITO, Masahiro NAKATA, and Yoshiaki NAKAZAWA. "Effects of Sheared Sheet-Edge Quality on Flange-Up Formability." Journal of the Japan Society for Technology of Plasticity 57, no. 670 (2016): 1062–69. http://dx.doi.org/10.9773/sosei.57.1062.

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24

Wolfson, Richard. "Current sheet formation in a sheared force-free-magnetic field." Astrophysical Journal 344 (September 1989): 471. http://dx.doi.org/10.1086/167816.

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25

Li, Qian, Gang He, Deng Lin Zhu, Jin Rong Wang, and Zhi Bin Leng. "Finite Element Analysis on the Rigidity of the Blade Carrier in a Guillotine Sheet-Metal Shear." Key Engineering Materials 522 (August 2012): 472–75. http://dx.doi.org/10.4028/www.scientific.net/kem.522.472.

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The rigidity of the sheet-metal shears blade carrier affects the shearing quality greatly. The straightness of the processed sheet-metal will decrease and burrs will increase if the rigidity is too low, which even leads to crack of the blade and decrease of the shearing ability of the sheet-metal shear. The model of the blade carrier in a new guillotine sheet-metal shear in Yawei Machine Tool Co., Ltd was established to study its rigidity. The distortion principle of the blade carrier was deduced using a finite element method. The analysis results are coinciding to the measurement result well. The method proposed in this study provides a guide to the design and intensity alignment of the blade carrier in guillotine sheet-metal shear.

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26

Guyoti, Viviane Marques, Mariana de Souza Farias, Magnus Larruscaim Dalmolin, César Henrique Poli, Verônica Schmidt, and Felix Diaz Gonzalez. "EFFECT OF SHEARING DURING PREGNANCY ON PRODUCTIVE PERFORMANCE IN THE POST-PARTUM PERIOD OF EWES ON EXTENSIVE HUSBANDRY." Ciência Animal Brasileira 16, no. 2 (June 2015): 217–24. http://dx.doi.org/10.1590/1089-6891v16i233219.

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The use of shearing during pregnancy has been described as a tool for improving productivity in sheep and for minimizing perinatal mortality in lambs through the increase of fetal development. This study assessed the effect of shearing around 74 days of gestation on the productive performance of ewes and lambs during the first month of life. Forty Corriedale ewes were inseminated in autumn in Southern Brazil. All ewes were kept together at the same pasture under extensive husbandry conditions. The ewes were randomly separated into two treatment groups: twenty animals were completely sheared at 74 ± 6 days of pregnancy, and twenty were kept without sheared during pregnancy, composing the control group. Ewes and their lambs were evaluated at three different times during the experiment: at birth, between 15 and 21 days post-partum and between 22 and 45 days post-partum. Ewes had their body condition score, body weight, placental weight, milk production and serum concentrations of beta-hydroxybutyrate measured, while lambs had hematocrit, hemoglobin, and plasma lactate and glucose, as well as body weight at birth and until wean determined. Values of hematocrit and hemoglobin were lower and body weight at birth and at wean was higher in the group of lambs born from sheared ewes. Placenta weight was higher in sheared ewes. Body condition score and beta-hydroxybutyrate showed no differences between groups. Milk production of sheared ewes (1.26 L/day) was higher than in control group (0.93 L/day). Shearing ewes at 74 days of pregnancy was efficient for the better development of lambs at post-birth, reducing perinatal mortality rates.

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Lai, Joseph C. S., Colin Speakman, and Hugh M. Williamson. "Control of Shear Cutting Noise: Effectiveness of Passive Control Measures." Noise & Vibration Worldwide 33, no. 7 (July 2002): 6–12. http://dx.doi.org/10.1260/09574560260370079.

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In an attempt to reduce noise from roll former shears three noise abatement enclosures of different designs and sheet dampers were assessed. Results indicate that only a noise reduction of 5dB can be achieved at the operator position by noise abatement enclosures, virtually independent of their designs and materials. This rather poor performance of enclosures is basically caused by structure-borne paths whereby vibrations are transmitted through the metal sheet product itself from the inside of the enclosure to the outside. Sheet dampers which have been designed to reduce the impact induced vibrations of the sheet product achieves a similar noise reduction as the enclosures but at about one quarter of the cost.

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Hatanaka, Nobuo, Katsuhiko Yamaguchi, Norio Takakura, and Takasi Iizuka. "Simulation of sheared edge formation process in blanking of sheet metals." Journal of Materials Processing Technology 140, no. 1-3 (September 2003): 628–34. http://dx.doi.org/10.1016/s0924-0136(03)00803-3.

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Golovashchenko, Sergey, Weitian Zhou, Saeid Nasheralahkami, and Nan Wang. "Trimming and Sheared Edge Stretchability of Light Weight Sheet Metal Blanks." Procedia Engineering 207 (2017): 1552–57. http://dx.doi.org/10.1016/j.proeng.2017.10.1077.

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Ugai, M. "Magnetic field structure of large-scale plasmoid generated by the fast reconnection mechanism in a sheared current sheet." Annales Geophysicae 28, no. 8 (August 11, 2010): 1511–21. http://dx.doi.org/10.5194/angeo-28-1511-2010.

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Abstract. On the basis of the spontaneous fast reconnection model, three-dimensional magnetic field profiles associated with a large-scale plasmoid propagating along the antiparallel magnetic fields are studied in the general sheared current sheet system. The plasmoid is generated ahead of the fast reconnection jet as a result of distinct compression of the magnetized plasma. Inside the plasmoid, the sheared (east-west) field component has the peak value at the plasmoid center located at x=XC, where the north-south field component changes its sign. The plasmoid center corresponds to the so-called contact discontinuity that bounds the reconnected field lines in x<XC and the field lines without reconnection in x>XC. Hence, contray to the conventional prediction, the reconnected sheared field lines in x<XC are not spiral or helical, since they cannot be topologically connected to the field lines in x>XC. It is demonstrated that the resulting profiles of magnetic field components inside the plasmoid are, in principle, consistent with satellite observations. In the ambient magnetic field region outside the plasmoid too, the magnetic field profiles are in good agreement with the well-known observations of traveling compression regions (TCRs).

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Kondoh, K., and M. Ugai. "Three-dimensional earthward fast flow in the near-Earth plasma sheet in a sheared field: comparisons between simulations and observations." Annales Geophysicae 27, no. 6 (June 8, 2009): 2297–302. http://dx.doi.org/10.5194/angeo-27-2297-2009.

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Abstract. Three-dimensional configuration of earthward fast flow in the near-Earth plasma sheet is studied using three-dimensional magnetohydrodynamics (MHD) simulations on the basis of the spontaneous fast reconnection model. In this study, the sheared magnetic field in the plasma sheet is newly considered in order to investigate the effects of it to the earthward fast flow, and the results are discussed in comparison with no-shear simulations. The virtual probes located at different positions in our simulation domain in shear/no-shear cases could explain different behavior of fast flows in the real observations.

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McKay, J. C. "Fibre production in angora rabbits." Proceedings of the British Society of Animal Production (1972) 1990 (March 1990): 67. http://dx.doi.org/10.1017/s0308229600018481.

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Angora rabbits carry a mutation.which confers continuous wool growth. The use of the wool in textiles was first recorded in 1706 in the U.K. and western Europe dominated world production until the the early 20th century. China now produces 60 percent of the world's 4,000 tonne annual crop.Genetic and nutritional improvements have led to a five-fold increase in annual yields over the last 40 years. Current commercial strains produce up to 1.5 Kg of wool per year from rabbits weighing 4 Kg. To maintain such yields requires concentrate diets with protein contents of at least 16 percent and cystine+methionine contents of 0.8 percent.The wool may be sheared or plucked and consists of three fibre types. The wool hairs (80 percent of the fleece) are among the finest animal fibres at 8-12 microns. They have a hollow medulla which gives important properties of low density (1.23 grams per ml versus 1.3 for sheep wool) and high thermal insulation (2-3 times that of sheep wool).

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Rosochowski, Andrzej, Lech Olejnik, and Malgorzata Rosochowska. "Tailored Sheared Blanks Produced by Incremental ECAP." Key Engineering Materials 651-653 (July 2015): 651–56. http://dx.doi.org/10.4028/www.scientific.net/kem.651-653.651.

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Incremental equal channel angular pressing (I-ECAP) is a process used for production of continuous ultrafine grained bars, plates and sheets. Normally the thickness of the processed billet is kept unchanged in consecutive passes to enable repetitive insertion into the same die. This is achieved by controlling the bottom dead centre of the reciprocating punch. However, if a final product requires being thinner and therefore longer, the bottom position of the punch can be lowered before the last pass. Going further, the bottom position of the punch can be changed during the process, which opens up a possibility to vary billet thickness along its length. Such a product, especially sheet, can serve as a preform for further metal forming operations and is known as tailored blank. This paper will show examples of varying thickness sheets produced by different configurations of I-ECAP. Experimental and finite element results will be presented.

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Davies-Jones, Robert, and Paul Markowski. "Lifting of Ambient Air by Density Currents in Sheared Environments." Journal of the Atmospheric Sciences 70, no. 4 (April 1, 2013): 1204–15. http://dx.doi.org/10.1175/jas-d-12-0149.1.

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Abstract Two aspects of vorticity associated with cold pools are addressed. First, tilting of horizontal vortex tubes by the updraft at a gust front has been proposed as a means of getting near-ground rotation and hence a tornado. Theory and a numerical simulation are used to show that this mechanism will not work because warm air parcels approaching the gust front decelerate in strong adverse pressure gradient. The near-surface horizontal vorticity available for upward tilting is greatly reduced by horizontal compression before it is tilted. Consequently, uplifting of vortex tubes produces little vertical vorticity near the ground. Second, it is shown that the baroclinic vorticity generated at the leading edge of the cold pool is transported rearward in the vortex sheet along the interface between cold and warm air, and the barotropic vorticity associated with environmental shear is conserved along streamlines. Warm parcels away from the interface do not acquire baroclinic vorticity to offset their barotropic vorticity, as assumed in a theory for long-lived squall lines. The vortex sheet has a far-field effect on the circulation in the warm air. A steady-state vortex method is used to propose why there is a steady noncirculating density current only when a lid is present and at a specific height.

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Nagasawa, Shigeru, Yuuya Masaki, Masatoshi Fujikura, and Yasushi Fukuzawa. "Cutting Characteristic of Polycarbonate Sheet Subjected to Wedge Indentation by Knife Edge and Grooved Plate." Key Engineering Materials 443 (June 2010): 602–7. http://dx.doi.org/10.4028/www.scientific.net/kem.443.602.

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Asymmetric plunge cutting by using grooved knife edge plate was proposed for advanced die cutting of a polycarbonate (PC) sheet. By varying the tip angle U and the tip thickness wU of knife edge in the counter plate, and combining a standard steel cutting rule of 42° center bevel blade, a cutting load response of PC sheet was investigated and also that deformation was observed by a CCD camera. Through this works, the followings were found: 1) there were two deformation modes of sheared profile. 2) The tip thickness wU was a primary factor, compared to the tip angle of U. 3) The equivalent wedge angle effect was revealed with respect to the upper/lower angles  and U, while the PC sheet was bent up by the lower knife indentation.

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Wang, Jia-Quan, Sen-Lei Hou, Jian-Feng Xue, Zhi-Nan Lin, and Yi Tang. "Triaxial Shear Behavior of a Gravelly Sand with Different Forms of Reinforcement." Advances in Civil Engineering 2021 (February 18, 2021): 1–11. http://dx.doi.org/10.1155/2021/8891400.

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To study the effect of three-dimensional reinforcement arrangement on the behavior of a gravelly sand, triaxial tests were performed on specimens reinforced with geogrid sheet, geogrid cell, and one and two layers of geogrid sheet and geocell combination. Specimens with a diameter of 100 mm and a height of 200 mm are sheared under drained condition to monitor the variation of axial and volumetric strains with axial loading under different confining pressures. The results showed that the reinforcement schemes have different effects on soil strength improvement. The inclusion of double layers of geogrid sheet and geocell reinforcement could increase both the apparent cohesion and friction of the reinforced soil. The stress-strain relationship could be modelled with a modified hyperbolic model, which can capture the softening strain behavior of the specimens after peak strength.

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Tsuneta, Saku. "Solar Flares as an Ongoing Magnetic Reconnection Process." International Astronomical Union Colloquium 141 (1993): 239–48. http://dx.doi.org/10.1017/s025292110002916x.

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AbstractThe soft X-ray images taken by the Yohkoh Soft X-ray Telescope (SXT) provide a powerful new tool to solve the mechanism of solar flares. In particular, a limb flare that occurred on 1991, December 2 gives us convincing evidence that magnetic reconnection of a neutral sheet formed at the loop top participates in the flare energy release. The neutral sheet appears to be associated with a destabilized rising loop system (filament) sheared with respect to the flaring loop. Similar formations of X-ray arcades are seen in the quiet Sun associated with filament eruptions on much larger spatial dimension and with a much smaller energy scale.

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Karpen, Judith T., Spiro K. Antiochos, and C. R. Devore. "Coronal current-sheet formation - The effect of asymmetric and symmetric shears." Astrophysical Journal 382 (November 1991): 327. http://dx.doi.org/10.1086/170720.

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Wedgwood, Stephen, Calista J. Mitchell, Jeffrey R. Fineman, and Stephen M. Black. "Developmental differences in the shear stress-induced expression of endothelial NO synthase: changing role of AP-1." American Journal of Physiology-Lung Cellular and Molecular Physiology 284, no. 4 (April 1, 2003): L650—L662. http://dx.doi.org/10.1152/ajplung.00252.2002.

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Endothelial nitric oxide synthase (eNOS) mRNA and protein levels increase during late gestation and then decrease postnatally in sheep lung parenchyma. The increase in fluid shear stress at birth, resulting from increased pulmonary blood flow, is an important mediator of postnatal eNOS gene expression. Our objective was to identify factors stimulating eNOS expression in pulmonary arterial endothelial cells (PAEC) in response to shear stress and to determine if these factors are developmentally regulated. PAEC were isolated from fetal lambs and adult sheep. Transcriptional activity from a 1,600-bp eNOS promoter fragment increased in both fetal and adult PAEC exposed to 8 h of shear stress. Conversely, activity driven from an 840-bp promoter fragment containing a putative activator protein (AP)-1 binding site was increased only in fetal PAEC. This increase was completely abolished in an identical construct containing a mutant AP-1 sequence. The AP-1 protein c-Jun was localized to the cytosol in static adult PAEC and to the nucleus in static fetal PAEC. After shear, c-Jun was nuclear localized in both cell types. However, transcriptionally active phosphorylated c-Jun was elevated only in the nuclei of sheared fetal PAEC. Resting levels of eNOS and NO were 2- and 20-fold higher, respectively, in fetal cells. Shear increased eNOS and NO in both cell types: levels were ∼2.5-fold higher in fetal PAEC. Phosphorylation of Akt and eNOS was evident in sheared fetal but not adult PAEC. We have therefore identified mechanisms of eNOS regulation at the transcriptional level and to be enzyme activation specific to the fetal pulmonary arterial circulation.

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Artemyev, A. V., A. I. Neishtadt, and L. M. Zelenyi. "Ion motion in the current sheet with sheared magnetic field – Part 2: Non-adiabatic effects." Nonlinear Processes in Geophysics 20, no. 5 (October 31, 2013): 899–919. http://dx.doi.org/10.5194/npg-20-899-2013.

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Abstract. We investigate dynamics of charged particles in current sheets with the sheared magnetic field. In our previouspaper (Artemyev et al., 2013) we studied the particle motion in such magnetic field configurations on the basis of the quasi-adiabatic theory and conservation of the quasi-adiabatic invariant. In this paper we concentrate on violation of the adiabaticity due to jumps of this invariant and the corresponding effects of stochastization of a particle motion. We compare effects of geometrical and dynamical jumps, which occur due to the presence of the separatrix in the phase plane of charged particle motion. We show that due to the presence of the magnetic field shear, the average value of dynamical jumps is not equal to zero. This effect results in the decrease of the time interval necessary for stochastization of trapped particle motion. We investigate also the effect of the magnetic field shear on transient trajectories, which cross the current sheet boundaries. Presence of the magnetic field shear leads to the asymmetry of reflection and transition of particles in the current sheet. We discuss the possible influence of single-particle effects revealed in this paper on the current sheet structure and dynamics.

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Spišák, Emil, Janka Majerníková, Ľuboš Kaščák, and Peter Mulidran. "THE IMPACT OF SHEAR GAP SIZE ON THE QUALITY OF THE SHEARED SURFACE IN ELECTRICAL STEEL SHEET BLANKING." Acta Metallurgica Slovaca 26, no. 2 (June 4, 2020): 49–53. http://dx.doi.org/10.36547/ams.26.2.545.

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The quality of the sheared surface when blanking, also known as die-cutting, is the result of several factors. Based on current knowledge about blanking, the following technological parameters – shear gap size, blunting of the shearing tool, lubrication in the shearing process, and deformation rate – can be considered as decisive parameters on the quality of the sheared surface. The main material characteristics include yield strength, tensile strength, ductility, and ferrite grain size. The paper is focused on the influence of the shear gap on the quality of the shear surface of electrical sheets with different chemical composition and different mechanical properties. The quality of the cutting surface was characterized by the size of the plastic cutting area. The relationships between the size of the shear gap, which ranged from 1 to 7% of the thickness of the cut material and the size of the plastic shear area, were evaluated and measured macroscopically.

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Rafiee, Reza, Bernard F. Rolfe, and Wen Yi Yan. "Simulation of Contact Pressure in Sheet Metal Trimming/ Blanking Process." Advanced Materials Research 41-42 (April 2008): 463–68. http://dx.doi.org/10.4028/www.scientific.net/amr.41-42.463.

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In the car body stamping process, trim/blank die cutting edges are subjected to very high tribological loads that result in loss of tool material from both the punch and die cutting edges. According to Archard’s wear model, normal contact force and sliding distance directly affects the wear. Therefore, knowledge of the acting forces on local contact areas has a pivotal role towards the prediction of tool wear. This paper presents a finite element modelling approach to determining the contact pressure distribution on the tool cutting edges during a trimming/blanking process. Characteristic areas on sheared edge profile, variation of punch force and high contact pressures affected areas have also been analysed.

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Čačko, Viliam, Iveta Onderová, Ľubomír Šooš, Pavol Varga, and Andrej Smelík. "Experimental Determination of Mechanical Properties of Waste Steel Sheets." Materials Science Forum 994 (May 2020): 62–69. http://dx.doi.org/10.4028/www.scientific.net/msf.994.62.

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The paper is primarily focused on the determination of the ultimate strength of pressed materials in the form of steel sheets. The breaking strength of homogeneous materials such as e.g. steel sheet is not a relevant indication for pressed steel sheet waste material. The ultimate strength serves as a main parameter in the design of sheet metal cutting machines. For the design and technological design of machines and equipment for shearing steel waste in the form of pressed sheets, it is necessary to know the limit strength of the material. The paper describes in detail the experimental procedure and the principle of determining the ultimate strength of the steel waste sheet. Several dozen experimental samples of pressed metal waste were used. The very principle of the experiment consisted of sheared samples, while monitoring the shear force and the thickness of the pressed material. The ultimate strength of the shear material was calculated from the measured data. The measured and calculated data were statistically processed to increase the objectivity of the determination of the already mentioned ultimate strength parameter of the pressed waste sheets.

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Kwok, Adrian, David Nevell, Alan Ferrier, Nicole Graf, Alan Lam, and Robert Ford. "Comparison of Tissue Injury between Laparosonic Coagulating Shears and Electrosurgical Scissors in the Sheep Model." Journal of the American Association of Gynecologic Laparoscopists 8, no. 3 (August 2001): 378–84. http://dx.doi.org/10.1016/s1074-3804(05)60334-9.

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45

Ugai, M. "Three-dimensional evolution of the fast reconnection mechanism in a sheared current sheet." Physics of Plasmas 17, no. 3 (March 2010): 032313. http://dx.doi.org/10.1063/1.3369886.

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46

Odier, Nicolas, Guillaume Balarac, Christophe Corre, and Vincent Moureau. "Numerical study of a flapping liquid sheet sheared by a high-speed stream." International Journal of Multiphase Flow 77 (December 2015): 196–208. http://dx.doi.org/10.1016/j.ijmultiphaseflow.2015.08.001.

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47

Fan, Wei Fu, Jian Hua Li, and Zhong Mei Zhang. "Study on the Process of Pure Shearing and Fracture for AISI-1020 and AISI-1045 Blanking with Negative Clearance." Advanced Materials Research 135 (October 2010): 215–19. http://dx.doi.org/10.4028/www.scientific.net/amr.135.215.

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This paper carried through fine-blanking with negative clearance processing experiment with the AISI-1020 and AISI-1045 and obtained the work piece of fine blanking with negative clearance. The fractography photographs in the different deform regions of rollover zone, shearing band, fracture zone and under sheared surface were scanned by scanning electron microscope (SEM-JSM-6360LV). The research result indicates that the plastic flow of fine-blanking with negative clearance has been carried out to punch downspin, then jib at the place of allowance value, so that the length of work piece burnish band as much as possible to maximize and the length of the smooth shearing fracture could reach more than 90% thickness of the metallic sheet. Owing to the ejector negative direction blanking, the second burnish band could be formed in the process of ejecting and the work piece has no burr in the undermost sheared face. The place of fracture of fine-blanking with negative clearance has emerged into the middle of work piece, not into the sheared undermost. And the width of fracture band is very tiny, only 50-100 micron. The research result provides theoretic reference and the experimental data for the practice application. It has instructive significance and reference value to manufacturing application.

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48

Artemyev, A. V., A. I. Neishtadt, and L. M. Zelenyi. "Ion motion in the current sheet with sheared magnetic field – Part 1: Quasi-adiabatic theory." Nonlinear Processes in Geophysics 20, no. 1 (February 21, 2013): 163–78. http://dx.doi.org/10.5194/npg-20-163-2013.

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Abstract. We present a theory of trapped ion motion in the magnetotail current sheet with a constant dawn–dusk component of the magnetic field. Particle trajectories are described analytically using the quasi-adiabatic invariant corresponding to averaging of fast oscillations around the tangential component of the magnetic field. We consider particle dynamics in the quasi-adiabatic approximation and demonstrate that the principal role is played by large (so called geometrical) jumps of the quasi-adiabatic invariant. These jumps appear due to the current sheet asymmetry related to the presence of the dawn–dusk magnetic field. The analytical description is compared with results of numerical integration. We show that there are four possible regimes of particle motion. Each regime is characterized by certain ranges of values of the dawn–dusk magnetic field and particle energy. We find the critical value of the dawn–dusk magnetic field, where jumps of the quasi-adiabatic invariant vanish.

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Hoffmann, Hartmut, and Florian Hörmann. "Improving the Cut Edge by Counter-Shaving." Key Engineering Materials 344 (July 2007): 217–24. http://dx.doi.org/10.4028/www.scientific.net/kem.344.217.

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In blanking operations the cut edge of the sheet metal is not clear due to fracturing and burr formation by the shearing process. For precision parts with high quality and dimensional accuracy, often secondary machining is necessary. Shaving, in particular, counter-shaving, is a shearing operation to improve the cut edge quality of a blanked part or punched hole in two stages. This paper introduces a progressive die tool to realize the counter-shaving process on a single acting press. In order to realize the shaving operation in the opposite punching direction, the punch needs to move in counter direction. The burr and fracture zone left on the sheet metal after the first stage will be removed by the counter-shaving operation. By choosing the right process parameter a sharpedge transition is formed, without any rollover, between the upper surface of the sheet metal and the sheared-edge. Different punch geometries as well as the corresponding process parameters were part of the research work in order to improve the cut edge. Experimental and FEM results are presented for two sheet metal materials at three thicknesses.

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Zoet, Lucas K., and Neal R. Iverson. "A slip law for glaciers on deformable beds." Science 368, no. 6486 (April 2, 2020): 76–78. http://dx.doi.org/10.1126/science.aaz1183.

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Slip of marine-terminating ice streams over beds of deformable till is responsible for most of the contribution of the West Antarctic Ice Sheet to sea level rise. Flow models of the ice sheet and till-bedded glaciers elsewhere require a law that relates slip resistance, slip velocity, and water pressure at the bed. We present results of experiments in which pressurized ice at its melting temperature is slid over a water-saturated till bed. Steady-state slip resistance increases with slip velocity owing to sliding of ice across the bed, but above a threshold velocity, till shears at its rate-independent Coulomb strength. These results motivate a generalized slip law for glacier-flow models that combines processes of hard-bedded sliding and bed deformation.

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Journal articles on the topic 'Sheep shearers'

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