73 research outputs found

    Reusable Solid Rocket Motor - Accomplishments, Lessons, and a Culture of Success

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    The Reusable Solid Rocket Motor represents the largest solid rocket motor ever flown and the only human rated solid motor. Each Reusable Solid Rocket Motor (RSRM) provides approximately 3-million lb of thrust to lift the integrated Space Shuttle vehicle from the launch pad. The motors burn out approximately 2 minutes later, separate from the vehicle and are recovered and refurbished. The size of the motor and the need for high reliability were challenges. Thrust shaping, via shaping of the propellant grain, was needed to limit structural loads during ascent. The motor design evolved through several block upgrades to increase performance and to increase safety and reliability. A major redesign occurred after STS-51L with the Redesigned Solid Rocket Motor. Significant improvements in the joint sealing systems were added. Design improvements continued throughout the Program via block changes with a number of innovations including development of low temperature o-ring materials and incorporation of a unique carbon fiber rope thermal barrier material. Recovery of the motors and post flight inspection improved understanding of hardware performance, and led to key design improvements. Because of the multidecade program duration material obsolescence was addressed, and requalification of materials and vendors was sometimes needed. Thermal protection systems and ablatives were used to protect the motor cases and nozzle structures. Significant understanding of design and manufacturing features of the ablatives was developed during the program resulting in optimization of design features and processing parameters. The project advanced technology in eliminating ozone-depleting materials in manufacturing processes and the development of an asbestos-free case insulation. Manufacturing processes for the large motor components were unique and safety in the manufacturing environment was a special concern. Transportation and handling approaches were also needed for the large hardware segments. The reusable solid rocket motor achieved significant reliability via process control, ground test programs, and postflight assessment. Process control is mandatory for a solid rocket motor as an acceptance test of the delivered product is not feasible. Process control included process failure modes and effects analysis, statistical process control, witness panels, and process product integrity audits. Material controls and inspections were maintained throughout the sub tier vendors. Material fingerprinting was employed to assess any drift in delivered material properties. The RSRM maintained both full scale and sub-scale test articles. These enabled continuous improvement of design and evaluation of process control and material behavior. Additionally RSRM reliability was achieved through attention to detail in post flight assessment to observe any shift in performance. The postflight analysis and inspections provided invaluable reliability data as it enables observation of actual flight performance, most of which would not be available if the motors were not recovered. These unique challenges, features of the reusable solid rocket motor, materials and manufacturing issues, and design improvements will be discussed in the paper

    Backward and Forward Compatibility

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    In response to the European Union (EU) Restriction of Hazardous Substances (RoHS) and other countriesā€™ impending lead-free directives, the electronics industry is moving toward lead-free soldering. Total lead-free soldering requires not only lead-free solder paste but also lead-free printed circuit board (PCB) finish and lead-free component/packages. Transitioning tin-lead (SnPb) soldering to totally lead-free soldering is a complex issue and involves movement of the whole electronics industry supply chain. In reality, there is a transition period

    The tegula tango: A coevolutionary dance of interacting, positively selected sperm and egg proteins

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    Reproductive proteins commonly show signs of rapid divergence driven by positive selection. The mechanisms driving these changes have remained ambiguous in part because interacting male and female proteins have rarely been examined. We isolate an egg protein the vitelline envelope receptor for lysin (VERL) from Tegula, a genus of free-spawning marine snails. Like VERL from abalone, Tegula VERL is a major component of the VE surrounding the egg, includes a conserved zona pellucida (ZP) domain at its C-terminus, and possesses a unique, negatively charged domain of about 150 amino acids implicated in interactions with the positively charged lysin. Unlike for abalone VERL, where this unique VERL domain occurs in a tandem array of 22 repeats, Tegula VERL has just one such domain. Interspecific comparisons show that both lysin and the VERL domain diverge via positive selection, whereas the ZP domain evolves neutrally. Rates of nonsynonymous substitution are correlated between lysin and the VERL domain, consistent with sexual antagonism, although lineage-specific effects, perhaps owing to different ecologies, may alter the relative evolutionary rates of sperm- and egg-borne proteins. Ā© 2012 The Author(s). Evolution Ā© 2012 The Society for the Study of Evolution

    Role of Cerebral Blood Flow in Extreme Breath Holding

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    The role of cerebral blood flow (CBF) on a maximal breath-hold (BH) in ultra-elite divers was examined. Divers (n = 7) performed one control BH, and one BH following oral administration of the non-selective cyclooxygenase inhibitor indomethacin (1.2 mg/kg). Arterial blood gases and CBF were measured prior to (baseline), and at BH termination. Compared to control, indomethacin reduced baseline CBF and cerebral delivery of oxygen (CDO(2)) by about 26% (p < 0.01). Indomethacin reduced maximal BH time from 339 Ā± 51 to 319 Ā± 57 seconds (p = 0.04). In both conditions, the CDO(2) remained unchanged from baseline to the termination of apnea. At BH termination, arterial oxygen tension was higher following oral administration of indomethacin compared to control (4.05 Ā± 0.45 vs. 3.44 Ā± 0.32 kPa). The absolute increase in CBF from baseline to the termination of apnea was lower with indomethacin (p = 0.01). These findings indicate that the impact of CBF on maximal BH time is likely attributable to its influence on cerebral H(+) washout, and therefore central chemoreceptive drive to breathe, rather than to CDO(2)

    The Vehicle, Fall 2006

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    Table of Contents Ferris WheelEmily Daviscover HerStephen Jefferiespage 1 UntitledBob Freyderpage 2 Writing at O\u27BrienWillie Joseph Morrispage 3 Blanks and HabitsRebecca M. Griffithpage 4 Soldier\u27s NightmareCraig A. Dennispage 5 UntitledLindsey Durbinpage 6 A Slow, Painless DeathJacob Fosterpage 7 ThoughtAmanda Yealepage 8 The SociopathBob Freyderpage 9 EasyRebecca M. Griffithpage 10 My PartnerDiedre Mapespage 11 BarriersSuzanne Krahnpage 12 The mind is a prisonJordan Hohespage 13 We Were Shirtless When Thousands DiedMitch Jamespage 14 ComplaintAmanda Yealepage 15 UntitledBob Freyderpage 16 MarkedAmanda Yealepage 17 She Wears Red Lipstick, He, Heartsick EyesRebecca M. Griffithpage 18 PrayerAmanda Yealepage 19 HomeDeej Rolewskipage 20 Your DreamDiedre Mapespage 21 Even Fingers Get LonelySuzanne Krahnpage 22 AggressivityMitch Jamespage 23 FallenMitch Jamespage 24 CollapseMario Podeschipage 36 The Italian CrisisAndy Masterspage 41 About the Authorshttps://thekeep.eiu.edu/vehicle/1084/thumbnail.jp

    The Vehicle, Fall 2006

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    Table of Contents Ferris WheelEmily Daviscover HerStephen Jefferiespage 1 UntitledBob Freyderpage 2 Writing at O\u27BrienWillie Joseph Morrispage 3 Blanks and HabitsRebecca M. Griffithpage 4 Soldier\u27s NightmareCraig A. Dennispage 5 UntitledLindsey Durbinpage 6 A Slow, Painless DeathJacob Fosterpage 7 ThoughtAmanda Yealepage 8 The SociopathBob Freyderpage 9 EasyRebecca M. Griffithpage 10 My PartnerDiedre Mapespage 11 BarriersSuzanne Krahnpage 12 The mind is a prisonJordan Hohespage 13 We Were Shirtless When Thousands DiedMitch Jamespage 14 ComplaintAmanda Yealepage 15 UntitledBob Freyderpage 16 MarkedAmanda Yealepage 17 She Wears Red Lipstick, He, Heartsick EyesRebecca M. Griffithpage 18 PrayerAmanda Yealepage 19 HomeDeej Rolewskipage 20 Your DreamDiedre Mapespage 21 Even Fingers Get LonelySuzanne Krahnpage 22 AggressivityMitch Jamespage 23 FallenMitch Jamespage 24 CollapseMario Podeschipage 36 The Italian CrisisAndy Masterspage 41 About the Authorshttps://thekeep.eiu.edu/vehicle/1084/thumbnail.jp

    Prospectus, December 14, 1983

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    MERRY CHRISTMAS TO ALL; Memories recalled from Christmases past; 32 are named in Who\u27s Who; News Digest; Parkland student talks with Santa; Simpson keeps position; Illinois joins no-fault divorce movement; PC Happenings: Second blood drive is success; German club goes to Chicago; Rotary scholarships available; Camera ban lifted; Final Exam Schedule; Looking forward to a winter like last year\u27s!; Parkland publishes annual magazine--Intercom; Zamary decorates cakes; Letter to the editor; Christmas carols are important part of world history; Letter to the editor; Question: When did you stop believing in Santa?; Question: What was the best Christmas gift you ever received?; Question: What is your best Christmas memory or tradition?; Christmas--ancient celebration of the birth of Christ; Spring brings more of an abundance of Cabbage Patches; The brighter side of Christmas; Make holiday cleaning easy; Tips for easier Holiday Baking; Tree trimming is art; Christmas cards originate in England; Recipes for Christmas and New Years; Christmas of yesteryear at the Lake of the Woods; Parkland before the brown brick campus; Photographer captures old-fashioned Christmas; Wham Bam it\u27s Tieken man and U.R.S.A..; Pulitzer winner at Krannert; WILL--most varied holiday line-up; Variety of films hits the 1983 Christmas season; Dylan is back again; \u27Stones\u27 come back to life; January Krannert Schedule; Classifieds; Tips on how to stay out of an accident on icy days; 1984 Bowl game schedule; Cobra volleyball players feted; Composite Athletic Schedule; I.M. News...; Women win; Track tream ready for season; Fire hazard safety tips; Local search for Opryland talent; President\u27s Christmas messagehttps://spark.parkland.edu/prospectus_1983/1000/thumbnail.jp

    The Lantern Vol. 61, No. 2, Summer 1994

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    ā€¢ She Was a Woman of Dignity ā€¢ Retake, Scene 16 ā€¢ Las Vegas Sweatshirt ā€¢ Pitcher Hill ā€¢ In Preparation for Wisdom (Teeth) ā€¢ Moist Slacks ā€¢ My Mother\u27s Purse ā€¢ It Comes and Goes Everyday ā€¢ The Simplicity of Marriage ā€¢ The First Performance ā€¢ Hunger ā€¢ Pushkin\u27s Dream ā€¢ Tuesday, October 19 ā€¢ Poetry of Baseball ā€¢ Some Things are More Important Than Others ā€¢ Musician ā€¢ Of What Befell Our Good Knight ā€¢ Piranha ā€¢ Oceans Apart ā€¢ Brooklyn Cantos ā€¢ Snowshower ā€¢ Thankfully in Australia ā€¢ Toothpaste and Tuna Fish ā€¢ Living Space ā€¢ Blue Monday ā€¢ Afterglow ā€¢ A Path to Consider ā€¢ Endless Summer ā€¢ Scaredy-Cathttps://digitalcommons.ursinus.edu/lantern/1144/thumbnail.jp
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