MEMS 411: Torsion Tester Design Report

The goal of this project is to provide the customer, Dr. James Jackson Potter, with a lightweight, inexpensive, and accurate alternative to modern, professional torsion-testing machines. The torsion tester developed by this team will be used in a classroom setting for design competitions on 3-D printed ABS plastic torsion bars; therefore the design also accommodate a range of functions which might be useful to the customer during testing competitions, potentially including automatic stopping at failure, a reset function, and the ability to create custom functions which can integrate into the existing function library

Feasibility study for a microwave-powered ozone sniffer aircraft

The preliminary design of a high-altitude, remotely-piloted, atmospheric-sampling aircraft powered by microwave energy beamed from ground-based antenna was completed. The vehicle has a gross weight of 6720 pounds and is sized to carry a 1000 pound payload at an altitude of 100,000 feet. The underside of the wing serves as the surface of a rectenna designed to receive microwave energy at a power density of 700 watts per square meter and the wing has a planform area of 3634 square feet to absorb the required power at an optimum Mach number M = 0.44. The aircraft utilizes a horizontal tail and a canard for longitudinal control and to enhance the structural rigidity of the twin fuselage configuration. The wing structure is designed to withstand a gust-induced load factor n = 3 at cruise altitude but the low-wing loading of the aircraft makes it very sensitive to gusts at low altitudes, which may induce load factors in excess of 20. A structural load alleviation system is therefore proposed to limit actual loads to the designed structural limit. Losses will require transmitted power on the order of megawatts to be radiated to the aircraft from the ground station, presenting environmental problems. Since the transmitting antenna would have a diameter of several hundred feet, it would not be readily transportable, so we propose that a single antenna be constructed at a site from which the aircraft is flown. The aircraft would be towed aloft to an initial altitude at which the microwave power would be utilized. The aircraft would climb to cruise altitude in a spiral flight path and orbit the transmitter in a gentle turn

A Competency-based Tool for Resident Evaluation of Pediatric Emergency Department Faculty

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Diagnosis of Posterior and Combined-Type Shoulder Instability: A 10-Year Cross-sectional Study From a Single Military Base

BACKGROUND: Large variations exist in the reported frequency and etiology of posterior and combined shoulder instability in the active-duty military population. PURPOSE: To compare imaging and clinical examination findings as well as reoperation rates between active-duty military patients who underwent surgery for anterior, posterior, and combined-type shoulder instability. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A retrospective review was conducted on patients treated surgically for shoulder instability from a single military base from January 2010 to December 2019. Each case was characterized as isolated anterior, isolated posterior, or combined, according to arthroscopic findings. Information was collected on patient characteristics, history of trauma, time to surgery, associated pathological findings, and survivorship at a minimum 2-year follow-up. RESULTS: Overall, 416 patients (n = 394 men; n = 22 women), with a mean age of 29.1 years, underwent primary shoulder stabilization surgery during the study period. There were 158 patients (38%) with isolated anterior instability, 139 (33%) with isolated posterior instability, and 119 (29%) with combined instability. A history of trauma was more prevalent with isolated anterior instability (129 [81.7%]) than with either isolated posterior (95 [68.4%]) or combined instability (73 [61.3%]) ( = .047 and = .001, respectively). Patients with anterior instability were significantly more likely to be diagnosed on the preoperative physical examination when compared with patients with posterior instability (93% vs 79.1%; \u3c .001) or combined instability (93% vs 75.6%; \u3c .001) and were also more likely to have a discrete labral tear detected on a preoperative magnetic resonance arthrogram than patients with posterior instability (82.9% vs 63.3%; \u3c .001). There was no significant difference in the rate of medical discharge or recurrent instability requiring reoperation between groups. CONCLUSION: The study findings indicated that young, active-duty military patients are at increased risk for isolated posterior and combined-type shoulder instability, with posterior and combined instability collectively accounting for over 60% of instability cases in this cohort. Orthopaedic surgeons should be aware of instability when evaluating and treating young, active-duty military patients with shoulder pain, even in the absence of diagnostic physical examinations or imaging findings