2,280 research outputs found

    Development of a Socketed Foundation for the Midwest Weak Post V1

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    A socketed foundation was designed and evaluated for use with the Midwest Weak Post (MWP), Version 1. Dynamic component testing was conducted on five different design configurations with varying embedment depths, steel reinforcement, and soil conditions. The low strength of the MWPs limited the force transferred into the foundations and prevented damage in the form of concrete cracking or fracture. Additionally, the lateral movements of the socketed foundations were all within the 1-in. (25-mm) limit established to ensure reuse of the foundations without resetting. The selected design consisted of a 12-in. (305-mm) diameter concrete shaft reinforced with four vertical bars and transverse hoop steel spaced at 6½ in. (165 mm) on center. A 4-in. x 3-in. x ¼-in. (102-mm x 76-mm x 6-mm) steel tube socket was placed in the middle of the shaft. Finally, guidelines were given for the length, or embedment depth, of the foundation based on surrounding soil conditions and risk of frost heave

    Development of a Transition Between an Energy-Absorbing Concrete Barrier and a Rigid Concrete Butress

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    From 2010 to 2015, MwRSF researchers developed the RESTORE barrier, which is a restorable MASH TL-4 median barrier with a steel and concrete rail supported by elastomer posts and steel skids. The research effort reported herein describes the initial development of a transition from the RESTORE barrier to a rigid TL-4 concrete buttress. The previously-developed RESTORE barrier LS-DYNA model was validated against three full-scale vehicle crash tests. Several design concepts were generated through a series of brainstorming efforts. The primary transition concept consisted of a pin and loop connection between the RESTORE barrier and rigid concrete buttress, which was designed and evaluated with LS-DYNA computer simulation. Vehicle and system behavior were investigated using MASH test designation nos. 4-20, 4-21, and 4-22. Six horizontal gusset plates and drop-down pin allowed for limited deflection and rotation at the transition joint, but provided shear continuity between the two systems. A rounded-edge cover plate mitigated vehicle snag on the transition joint hardware. Eleven impact points were evaluated with each vehicle model to determine critical impact points for use in a future full-scale crash testing program. All occupant risk measures and vehicle stability were within MASH limits. Further design modifications are recommended to limit stresses in the transition joint hardware and to reduce excessive occupant compartment deformation that occurred when the small car impacted the concrete buttress end

    Development of a Transition Between an Energy-Absorbing Concrete Barrier and a Rigid Concrete Butress

    Get PDF
    From 2010 to 2015, MwRSF researchers developed the RESTORE barrier, which is a restorable MASH TL-4 median barrier with a steel and concrete rail supported by elastomer posts and steel skids. The research effort reported herein describes the initial development of a transition from the RESTORE barrier to a rigid TL-4 concrete buttress. The previously-developed RESTORE barrier LS-DYNA model was validated against three full-scale vehicle crash tests. Several design concepts were generated through a series of brainstorming efforts. The primary transition concept consisted of a pin and loop connection between the RESTORE barrier and rigid concrete buttress, which was designed and evaluated with LS-DYNA computer simulation. Vehicle and system behavior were investigated using MASH test designation nos. 4-20, 4-21, and 4-22. Six horizontal gusset plates and drop-down pin allowed for limited deflection and rotation at the transition joint, but provided shear continuity between the two systems. A rounded-edge cover plate mitigated vehicle snag on the transition joint hardware. Eleven impact points were evaluated with each vehicle model to determine critical impact points for use in a future full-scale crash testing program. All occupant risk measures and vehicle stability were within MASH limits. Further design modifications are recommended to limit stresses in the transition joint hardware and to reduce excessive occupant compartment deformation that occurred when the small car impacted the concrete buttress end

    Development of a Transition Between an Energy-Absorbing Concrete Barrier and a Rigid Concrete Butress

    Get PDF
    From 2010 to 2015, MwRSF researchers developed the RESTORE barrier, which is a restorable MASH TL-4 median barrier with a steel and concrete rail supported by elastomer posts and steel skids. The research effort reported herein describes the initial development of a transition from the RESTORE barrier to a rigid TL-4 concrete buttress. The previously-developed RESTORE barrier LS-DYNA model was validated against three full-scale vehicle crash tests. Several design concepts were generated through a series of brainstorming efforts. The primary transition concept consisted of a pin and loop connection between the RESTORE barrier and rigid concrete buttress, which was designed and evaluated with LS-DYNA computer simulation. Vehicle and system behavior were investigated using MASH test designation nos. 4-20, 4-21, and 4-22. Six horizontal gusset plates and drop-down pin allowed for limited deflection and rotation at the transition joint, but provided shear continuity between the two systems. A rounded-edge cover plate mitigated vehicle snag on the transition joint hardware. Eleven impact points were evaluated with each vehicle model to determine critical impact points for use in a future full-scale crash testing program. All occupant risk measures and vehicle stability were within MASH limits. Further design modifications are recommended to limit stresses in the transition joint hardware and to reduce excessive occupant compartment deformation that occurred when the small car impacted the concrete buttress end

    The optical spectrum of a large isolated polycyclic aromatic hydrocarbon: hexa-peri-hexabenzocoronene, C42H18

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    The first optical spectrum of an isolated polycyclic aromatic hydrocarbon large enough to survive the photophysical conditions of the interstellar medium is reported. Vibronic bands of the first electronic transition of the all benzenoid polycyclic aromatic hydrocarbon hexa-peri-hexabenzocoronene were observed in the 4080-4530 Angstrom range by resonant 2-color 2-photon ionization spectroscopy. The strongest feature at 4264 Angstrom is estimated to have an oscillator strength of f=1.4x10^-3, placing an upper limit on the interstellar abundance of this polycyclic aromatic hydrocarbon at 4x10^12 cm^-2, accounting for a maximum of ~0.02% of interstellar carbon. This study opens up the possibility to rigorously test neutral polycyclic aromatic hydrocarbons as carriers of the diffuse interstellar bands in the near future.Comment: 9 pages, 1 figure. Fixed a typo on the frequency of the 'b' ban

    Universal Breakaway Steel Post for Other Applications

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    Clinical and functional impairment after nonoperative treatment of distal biceps ruptures

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    © 2018 Journal of Shoulder and Elbow Surgery Board of Trustees Background: Clinical and functional impairment after nonoperative treatment of distal biceps ruptures is not well understood. The goal of this study was to measure patients’ perceived disability, kinematic adjustment, and forearm supination power after nonoperative treatment of distal biceps ruptures. Methods: Fourteen individuals after nonoperative treatment of distal biceps ruptures were matched to a control group of 18 uninjured volunteers. Both groups prospectively completed the Disabilities of the Arm, Shoulder and Hand (DASH), Single Assessment Numerical Evaluation (SANE), and Biceps Disability Questionnaire. Both performed a new timed isotonic supination test that was designed to simulate activities of daily life. The isotonic torque dynamometer measures the supination arc, center of supination arc, torque, angular velocity, and power. Motion analysis quantifies forearm and shoulder contributions to the arc of supination. Results: The nonoperative treated group\u27s DASH (23.2 ± 10.3) and SANE (59.6 ± 16.2) scores demonstrated a clinical meaningful impairment. The control group showed no significant differences in kinematic values between dominant and nondominant arms (P =.854). The nonoperative biceps ruptured arms, compared with their uninjured arms, changed supination motion by decreasing the supination arc (P ≤.036), shifting the center of supination arc to a more pronated position (P ≤.030), and increasing the shoulder contribution to rotation (P ≤.001); despite this adaptation, their average corrected power of supination decreased by 47% (P =.001). Conclusion: Patients should understand that nonoperative treatment for distal biceps ruptures will result in varying degrees of functional loss as measured by the DASH, SANE, and Biceps Disability Questionnaire, change their supination kinematics during repetitive tasks, and that they will lose 47% of their supination power

    Ipsilateral and Contralateral Torque Responses to Bilateral and Unilateral Maximal, Fatiguing, Isokinetic Leg Extensions

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    Background: Few studies have compared performance fatigability (PF) for bilateral versus unilateral isokinetic tasks. Objectives: The purpose of this study was to examine: Mode- specific testing responses to isokinetic fatigue, differences in PF between bilateral and unilateral leg extensions, and the effects of fatiguing, unilateral, dynamic leg extensions on contralateral isokinetic peak torque (PT) and maximal voluntary isometric contraction (MVIC). Methods: Eight men (mean ± SD: age= 22.5 ± 2.5 yr.) completed pre- and post-testing for PT and MVIC following 50 bilateral, unilateral right or left leg maximal, isokinetic leg extensions at 180°·s-1, on three separate days. Fatigue-induced decreases in PT and MVIC were used to quantify PF. The data were analyzed with a 4-way repeated measures ANOVA, follow up, and post-hoc analyses. Results: The results indicated that there were no differences (p \u3e 0.05) in PF for the bilateral versus unilateral fatiguing tasks, decreases in PT (p \u3c 0.001 - 0.016; d = 0.54 - 2.58) and MVIC (p \u3c 0.001 - 0.006; η2p = 0.682 - 0.962) for the exercised legs during unilateral fatigue, and a contralateral increase (p = 0.007) in PT following the right leg fatiguing task. Conclusion: The results indicated that PT was more sensitive to fatiguing isokinetic tasks than was MVIC. In addition, there was a facilitation of PT in the contralateral leg following unilateral right leg fatigue. The differences in PT and MVIC testing may be attributable to the timing and/ or relative contributions of peripheral and central fatigue
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