Graphite fiber surface treatment to improve char retention and increase fiber clumping

Composites containing carbon and graphite fibers can release fibers into the atmosphere during a fire. This release can potentially cause failure in some types of electrical equipment. Reduced fiber dispersion during and after combustion will reduce risks. Epoxidized char forming systems were synthesized which will react with commercially available surface treated carbon fiber. Fibers modified with these char formers retained adhesion in a specific epoxy matrix resin. Small scale combustion testing indicates that using these char former modified fibers in laminates will help to reduce the dispersement of fibers resulting from exposure to fire without sacrificing resin to fiber adhesion

J-85 jet engine noise measured in the ONERA S1 wind tunnel and extrapolated to far field

Noise from a J-85 turbojet with a conical, convergent nozzle was measured in simulated flight in the ONERA S1 Wind Tunnel. Data are presented for several flight speeds up to 130 m/sec and for radiation angles of 40 to 160 degrees relative to the upstream direction. The jet was operated with subsonic and sonic exhaust speeds. A moving microphone on a 2 m sideline was used to survey the radiated sound field in the acoustically treated, closed test section. The data were extrapolated to a 122 m sideline by means of a multiple-sideline source-location method, which was used to identify the acoustic source regions, directivity patterns, and near field effects. The source-location method is described along with its advantages and disadvantages. Results indicate that the effects of simulated flight on J-85 noise are significant. At the maximum forward speed of 130 m/sec, the peak overall sound levels in the aft quadrant were attentuated approximately 10 dB relative to sound levels of the engine operated statically. As expected, the simulated flight and static data tended to merge in the forward quadrant as the radiation angle approached 40 degrees. There is evidence that internal engine or shock noise was important in the forward quadrant. The data are compared with published predictions for flight effects on pure jet noise and internal engine noise. A new empirical prediction is presented that relates the variation of internally generated engine noise or broadband shock noise to forward speed. Measured near field noise extrapolated to far field agrees reasonably well with data from similar engines tested statically outdoors, in flyover, in a wind tunnel, and on the Bertin Aerotrain. Anomalies in the results for the forward quadrant and for angles above 140 degrees are discussed. The multiple-sideline method proved to be cumbersome in this application, and it did not resolve all of the uncertainties associated with measurements of jet noise close to the jet. The simulation was complicated by wind-tunnel background noise and the propagation of low frequency sound around the circuit

Missed Moments: Kodak’s Failure to Define the Consumer Market for Digital Photography

The focus of this thesis is to provide an expanded interpretation of the decline of the Eastman Kodak Company. Kodak is a company synonymous with cameras, pictures, and photography. The American photographic giant created a vast empire that was able to dominate the industry for the better part of the Twentieth Century. Yet, it missed the opportunity to develop its digital camera technology. This makes Kodak an interesting study in business decision making in the face of advancing disruptive technology. In a historical context, there is a lack of work that deeply inspects the fall of the Kodak company in the late twentieth and early twenty-first century. The small amount of work available focuses on a narrow explanation for the decline of the company. A closer look reveals a more nuanced story that includes institutional restrictions coupled with a changing consumer electronics culture and business model. In this thesis, Kodak’s lack of desire to create a consumer market for digital photography is presented as a major misstep in the history of the company. It is not the aim of this work to exonerate or remove blame from the Kodak company for their actions. This thesis, drawing from primary documents found in the Eastman Kodak archives housed at The University of Rochester, aims to bring new ideas and explanations to the conversation. The argument presented should serve as an expansion of currently available interpretations which place singular blame on Kodak’s reliance on film profits for their downfall

Wind-Tunnel Survey of an Oscillating Flow Field for Application to Model Helicopter Rotor Testing

A survey was conducted of the flow field produced by the Airstream Oscillator System (AOS) in the Langley Transonic Dynamics Tunnel (TDT). The magnitude of a simulated gust field was measured at 15 locations in the plane of a typical model helicopter rotor when tested in the TDT using the Aeroelastic Rotor Experimental System (ARES) model. These measurements were made over a range of tunnel dynamic pressures typical of those used for an ARES test. The data indicate that the gust field produced by the AOS is non-uniform across the tunnel test section, but should be sufficient to excite a model rotor

Stress and burnout: insidious influences

Journal ArticleA career in neurosurgery may take a substantial toll on an individual?s body and mind. From the ?baptism by fire? experienced by a brand-new junior resident, to keeping one?s head above water as the residency proceeds, to the realization shortly after graduation of being responsible for the health and welfare of one?s patients, and finally to the difficulties of lifelong challenges in patient care and administration, neurosurgeons are under continual stress that varies considerably among individuals and lasts for the duration of one?s career

OR noise: the potential for hearing loss

Journal ArticleWith the use of the electric or air-powered drill in cranial or spinal procedures comes the potential for hearing loss among operating team members. Exposure to loud noise can result in sensorineural hearing loss, and this loss is a function of sound pressure levels and duration of exposure. Much research has been done regarding the impact of noise-creating devices on patient and user safety in the field of neuro-otology (1, 6). Michaelides and Kartush measured peak and impulse sound pressure levels one centimeter away from their application in the temporal bone in a variety of otologic instruments, including lasers (potassium-titanyl-phosphate, erbium, and carbon dioxide) and drills (microdrill and pneumatic) (4). Only the erbium laser and air-powered cutting drills had impulse and peak sound pressure levels of greater than 100 A-weighted decibels, dBA. Kylen and colleagues found that the noise levels were influenced primarily by the size of the burr; diamond burrs generated less noise than cutting ones and variations in rotation speed had only a slight influence on the noise levels produced (2). Prasad and Reddy recently tested a variety of bone drills and microdebriders used in otolaryngological surgery and found them all to be safe, posing no occupational hazard to the user (7)