Noise transmission loss of aircraft panels using acoustic intensity methods

The two-microphone, cross-spectral, acoustic intensity measurement technique was used to determine the acoustic transmission loss of three different aircraft panels. The study was conducted in the transmission loss apparatus in the Langley aircraft noise reduction laboratory

A new measurement method for separating airborne and structureborne noise radiated by aircraft type panels

The theoretical basis for and experimental validation of a measurement method for separating airborne and structure borne noise radiated by aircraft type panels are presented. An extension of the two microphone, cross spectral, acoustic intensity method combined with existing theory of sound radiation of thin shell structures of various designs, is restricted to the frequency range below the coincidence frequency of the structure. Consequently, the method lends itself to low frequency noise problems such as propeller harmonics. Both an aluminum sheet and two built up aircraft panel designs (two aluminum panels with frames and stringers) with and without added damping were measured. Results indicate that the method is quick, reliable, inexpensive, and can be applied to thin shell structures of various designs

Surface acoustical intensity measurements on a diesel engine

The use of surface intensity measurements as an alternative to the conventional selective wrapping technique of noise source identification and ranking on diesel engines was investigated. A six cylinder, in line turbocharged, 350 horsepower diesel engine was used. Sound power was measured under anechoic conditions for eight separate parts of the engine at steady state operating conditions using the conventional technique. Sound power measurements were repeated on five separate parts of the engine using the surface intensity at the same steady state operating conditions. The results were compared by plotting sound power level against frequency and noise source rankings for the two methods

Studies of noise transmission in advanced composite material structures

Noise characteristics of advanced composite material fuselages were discussed from the standpoints of applicable research programs and noise transmission theory. Experimental verification of the theory was also included

Down South, Up North's business plan

The following is the business plan for my new restaurant, "Down South, Up North." This restaurant will serve the DeKalb and Sycamore community, not only as a restaurant but as a breeding ground and/or stepping stone for aspiring entrepreneurs.B.S. (Bachelor of Science

The CAFE Experiment : a joint seismic and MT investigation of the Cascadia Subduction System

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2013In this thesis we present results from inversion of data using dense arrays of collocated seismic and magnetotelluric stations located in the Cascadia subduction zone region of central Washington. In the migrated seismic section, we clearly image the top of the slab and oceanic Moho, as well as a velocity increase corresponding to the eclogitization of the hydrated upper crust. A deeper velocity increase is interpreted as the eclogitization of metastable gabbros, assisted by fluids released from the dehydration of upper mantle chlorite. A low velocity feature interpreted as a fluid/melt phase is present above this transition. The serpentinized wedge and continental Moho are also imaged. The magnetotelluric image further constrains the fluid/melt features, showing a rising conductive feature that forms a column up to a conductor indicative of a magma chamber feeding Mt. Rainier. This feature also explains the disruption of the continental Moho found in the migrated image. Exploration of the assumption of smoothness implicit in the standard MT inversion provides tools that enable us to generate a more accurate MT model. This final MT model clearly demonstrates the link between slab derived fluids/melting and the Mt. Rainier magma chamber.Funding for this work was made possible by the American Society for Engineering education through a National Defense Science and Engineering Fellowship, and by the National Science Foundation through two grants for the CAFE and CAFE MT projects

Substandard reference solutions in chlorinity determinations by the Knudsen method

It is shown that natural sea water of any chlorinity may be used as a reference solution in the Knudsen method. The proper correction to apply to burette readings of samples can be obtained by means of the fundamental stoichiometric relationship used in computing the Table of Titration. A table of values for the construction of graphs from which the corrections can be obtained and a sample graph are included

Electrostatic Discharge Properties of Irradiated Nanocomposites

Modernization in space systems requires employment of new light-weight, high performance composite materials that reduce bulk weight and increase structural integrity. This thesis explored the behavior of one such material prior to and following a 35-year simulated space radiation life-cycle. Select electrical properties of nickel nanostrandTM-carbon composites in seven configurations were characterized prior to electron irradiation via surface and bulk resistivity measurements and contact electrostatic discharge (ESD) measurements. Following irradiation at a fluence of 1016 e-/cm2 at an average energy of 500 keV, measurements were repeated and compared against pre-irradiation data. Configuration D is the best configuration tested for use as a satellite external surface material. All composite configurations tested in this research showed degradation in critical electrical properties when examined in the aggregate. The data showed no common trend between the electrical performance of the various composites based on location or density of the nickel nanostrandsTM in the material. Surface resistivity increased for all configurations while bulk resistivity change correlated to the type of epoxy resin used in the composite. The mechanism responsible for these changes is electron induced displacement damage within both the epoxy and carbon which reduce permittivity and, or conductivity within the bulk. ESD current waveform properties of peak current and decay time decreased in a manner sufficient to conclude that every configuration tested is subject to increased ESD frequency and intensity over a lifetime of space radiation. These materials require further engineering to better resist the changes noted in these electrical properties before used as satellite surfaces

A Progress Report Of Three Years Study Of The Improvement Of Reading In Cass County, Texas

Statement of Problem The need to develop sound reading habits, interest, and taste in children, both in and out of school is greater now than ever before. Good reading is the most essential factor in school success. Reading is the master key which unlocks the gateway to every other subject and is both the most important and most troublesome subject in the elementary school curriculum. Yet the amount and quality of reading done by children and adults as well in general is disappointingly low. The study of any unselected group indicates that a large number of children in school are below normal in reading ability. When children in school are below normal in reading ability as to their grade level we search for the cause. We lay it to physical defects, such as poor eyesight, defective hearing, nervousness, and malnutrition. It is true those things are often contributing causes, but probably the greatest trouble with reading lies in the ability of teachers to make this difficult tool useful to the children. The reading problem faces every teacher. In primary grades, it is the most frequent cause of school failure. It is an important determiner of achievement in other school subjects in the intermediate grades. That it largely determines success or failure in upper grades as well, can easily be, understood, since it is a tool that is basic to nearly all learning