The fluid forces on a single cylinder in cross flow are measured experimentally by strain gauges. The drag and lift coefficients of the cylinder are measured with momentum injection of various direction and magnitude. The results show that the drag coefficient of the cylinder is reduced with momentum injection. For higher Reynolds numbers, the magnitude of momentum injection must be increased to maintain the effectiveness of momentum injection. The influence of the drag coefficient is reduced when the angle of momentum injection is increased, and then the lift coefficient is varied obviously.

Gun-drilling is one of the highly efficient tools for deep-hole making. The drilled hole possesses good size, positioning, roughness, roundness, and straightness. When the deep-hole is drilled, it is easy to cause wear at the tool-chip and tool-work interfaces at the serious condition so that the gun-drill is subjected to larger feed force. If the feed force exceeds the critical load, then the cutting edge of the gun-drill is broken. However, nowadays the device to measure the feed force in the gun-drill press is not available. This study develops a gun-drill press which possesses two new functions as follow: (1) to measure and to record the feed force during the drilling process;¡]2¡^to return the gun-drill when the feed force exceeds a set value. These two functions can be used to detect the serious breakage of the gun-drill. According to the practice drilling test, the performance of this press can be obtained. Results show that the feed force can be measured using different feed speeds. The gun-drill can stop and return to its origin position when the feed force exceeds the set value. Hence, the performance test of this new machine meets the above-mentioned functions. Using this press, the relationship between the feed force and the wear of cutting edge is investigated at the same feed speed. Results show that wear occurs on the cutting edge of the gun-drill, and the wear area increases with increasing drilling time so that the feed force is also increased. The wear grows from the outer side of the cutting edge to the inner side.

Thesis (Ph. D.)--University of Washington, 2008. / Vita. Includes bibliographical references (p. 278-280).

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 115-131). Available also in a digital version from Dissertation Abstracts.

Thesis (M.S. in Applied Physics)--Naval Postgraduate School, December 2009. / Thesis Advisor(s): Maier, William B. ; Crooker, Peter P. "December 2009." Description based on title screen as viewed on January 29, 2010. Author(s) subject terms: Railgun, Railgun recoil, Lorentz force, eutectic. Includes bibliographical references (p. 49-51). Also available in print.

Force majeure kan åberopas som ansvarsbefriande grund när något oförutsett och extraordinärt inträffar, vilket gör att en säljare inte kan fullgöra sin del av avtalet i tid.Begreppet är dock otydligt definierat i såväl lagtext som doktrin. Detta gör att förståelsen fördess användningsområde och tillämplighet är begränsad. På grund av att KöpL är dispositiv kommer force majeure idag oftast till uttryck genom friskrivningsklausuler i standardavtal. Som ett resultat av begreppets oklara innebörd utformas klausulerna på olika sätt, beroende på vilka som är parter, och ger därmed uttryck för olika situationer och omständigheter som kan ligga till grund för skadeståndsfrihet. Friskrivningsklausuler av typen force majeure har blivit allt vanligare, vilket tyder på att begreppet har börjat användas i en vidare utsträckning. Frågan blir således om det är rättssäkert och förutsebart att en part i avtalet ensam ges rätten att tolka huruvida det rör sig om force majeure? I uppsatsen undersöker vi hur begreppet force majeure har utvecklats från gamla till nya KöpL, samt hur force majeure används inom standardavtalsrätten som ansvarsbefriande grund. Detta har inneburit att en grundläggande utredning av 24 § gamla KöpL och 27 § nya KöpL har genomförts. Vi har även valt att beröra internationell köprätt, i form av CISG, eftersom denna ligger till grund för den svenska lagstiftningen. Dessutom har förarbeten, doktrin och internetkällor behandlats. Mot bakgrund av denna avsaknad av vägledning finner vi det motiverat att begreppet force majeure definieras tydligare i lagtext. Förslagsvis kan detta ske genom en uppräkning av händelser, vilka kan åberopas såsom force majeure, samt att hänsyn tas till eiusidem generis vid bedömningen. Detta innebär att de situationer som uppstår ska ha något gemensamt med de som räknas upp i paragrafen för att kunna leda till ansvarsfrihet. Ges begreppet en tydligare definition kan rättssäkerheten öka och därmed också ge avtalsparterna en ökad förståelse för vilka omständigheter som kan ligga till grund för ett åberopande av force majeure.

This study investigated how varying the required force level and the direction of force change produced by the thumb and index finger affect the accuracy and variability of a cyclic isometric pinch force-tracking task. Accuracy was examined by both absolute error and relative error for the minimum and maximum force levels and by root mean square error (RMSE) and normalized root mean square error (normalized RMSE) for the force direction reversals. Variability was represented by coefficient of variation of error (CVE). In this study, ‘maximum force’ was defined as the highest force level of a given target force range, and ‘minimum force’ was defined as the minimum force level of the target range. In addition, ‘force increasing to decreasing’ indicated that the track ball motion changed from increasing to decreasing, requiring the performer to exert increasing force up to the maximum force level and then decreasing force to follow the track ball moving toward the minimum force level. The phrase ‘force decreasing to increasing’ indicated the opposite force direction reversal. Eighteen healthy right handed adult volunteers (nine men and nine women; mean age ± SD, 28.3±1.22 and 26.4±1.74) participated in this study. The participants performed a cyclic isometric pinch force tracking task over three different force ranges. Force range 1 was from a minimum force of 3% of maximal voluntary contraction force (MVC) to a maximum force of 6% MVC. In force range 2, the range was from 6% to 12% MVC, and force range 3 was from 12% to 24% MVC. For each force range, five practice trials and ten actual test trials were performed. Rest periods of twenty seconds between trials and one minute between sets of trials (including between practice and actual test trials) were provided to minimize fatigue effects. Absolute error uniformly increased as a function of increasing force. However, the 3% target force level showed larger relative error compared to the 12% target force level (p < 0.05). Another finding of this study was that producing forces positioned at the minimum target level in a range yielded higher absolute error and relative error compared to the same forces when placed at the maximum target level of a different force range. In terms of the reversals, RMSE values were higher at the change from force deceasing to increasing than the opposite, as well as at higher force levels, while normalized RMSE values were greater at lower force levels. CVE was not significantly different between the two reversals in this study. This might indicate that poorer performance during the change from force decreasing to increasing could originate from the effort to maintain consistent performance and additional effort was not beneficial to increase accuracy for the change from force decreasing to increasing. / text

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No description available.

Abstract Isokinetic normative data can be invaluable in identifying an individual’s strengths and weaknesses, and thus lead to a more effective use of the individual’s time to minimise or overcome his weaknesses while maintaining or improving existing strength. However, visual feedback (VF) may significantly affect the result of isokinetic testing, resulting in erroneous conclusions if not accounted for. Additionally, the previous use of VF to obtain increased strength values has resulted in inconsistent findings. The purpose of this study was to examine the effect of VF on concentric and eccentric knee extensor peak torque. Twenty-two sedentary, college-aged male and female volunteers were assigned to either Group 1 (n = 11) or Group 2 (n = 11) to either perform knee extensor concentric-eccentric (con-ecc) isokinetic testing with VF or without VF (no-VF) using a crossover method. After a one-week rest, the two groups underwent knee extensor con-ecc isokinetic testing using the alternative testing condition. Each test consisted of five maximal knee extensor con-ecc isokinetic testing contractions at 60° per second on the Cybex Norm system. The data indicated significant (p < 0.05) differences in the concentric peak torque of Group 1, Group 2 and Combined Group following VF when compared to no-VF. The eccentric peak torque of Group 1, Group 2 and Combined Group was found not to be significantly different following VF when compared to no-VF. Further, no significant interaction effect as a result of the different groups was found. Visual feedback of torque output can improve maximum voluntary concentric contraction in isokinetic dynamometry, but not maximum voluntary eccentric contraction. It is thus recommended that VF should be consistently provided during isokinetic testing, since it can also be used to help detect and correct errors in performance as well as derive reinforcement from correct performances.