Arc spray fabrication of metal matrix composite monotape

Arc metal spraying is used to spray liquid metal onto an array of high strength fibers that were previously wound onto a large drum contained inside a controlled atmosphere chamber. This chamber is first evacuated to remove gaseous contaminants and then backfilled with a neutral gas up to atmospheric pressure. This process is used to produce a large size metal matrix composite monotape

Thermal-mechanical fatigue test apparatus for metal matrix composites and joint attachments

Two thermal-mechanical fatigue (TMF) test facilities were designed and developed, one to test tungsten fiber reinforced metal matrix composite specimens at temperature up to 1430C (2600F) and another to test composite/metal attachment bond joints at temperatures up to 760C (1400 F). The TMF facility designed for testing tungsten fiber reinforced metal matrix composites permits test specimen temperature excursions from room temperature to 1430C (2600F) with controlled heating and loading rates. A strain-measuring device measures the strain in the test section of the specimen during each heating and cooling cycle with superimposed loads. Data is collected and recorded by a computer. The second facility is designed to test composite/metal attachment bond joints and to permit heating to a maximum temperature of 760C (1400F) within 10 min and cooling to 150C (300F) within 3 min. A computer controls specimen temperature and load cycling

Thermal-conductivity measurements of tungsten-fiber-reinforced superalloy composites using a thermal-conductivity comparator

The thermal conductivity (TC) of tungsten-fiber-reinforced superalloys was determined for two composite systems by using a thermal conductivity standard from the National Bureau of Standards and a comparator and technique developed for that purpose. The results were compared with TC data for the nickel-base alloy MAR-M200. The technique lends itself to applications involving thin specimens, such as thin-walled turbine blades. The TC's of the composite systems were considerably higher in both the longitudinal and transverse directions than that of the monolithic superalloys used as the matrices

An Investigation of the Accuracy of a New Technique for Surgical Repositioning a Maxilla

Objectives: The purpose of this study was to test the method of the Four Faces of Orthognathic SurgeryRTM in regards to surgical accuracy and the ability to transfer this method to an academic setting. Methods: An experimental group consisted of 15 patients from a university setting and 17 patients from a private practice setting. Lateral cephalograms were taken immediately prior to the orthognathic procedure and post-operatively within six weeks. Pre-surgical, post-surgical cephalograms, and the hand generated surgical predictions were collected from the sample. The differences of planned and actual changes to incision were then analyzed to determine whether or not a statistical significance existed with respect to the following variables: surgical team, surgical complexity, and direction of maxillary movement. Results: The private practice sample evaluated in this study shows that 100% of the patients were treated to within 1mm of prediction. The university team sample had a greater variation in surgical accuracy than the private practice team with 87% of the patients treated within 2mm of prediction and 53% treated within 1mm of prediction. However, this variation is not statistically significant. When surgical complexity and the primary direction of maxillary movement were compared, no significant differences were found. Conclusions: The Four Faces of Orthognathic SurgeryRTM is a significantly accurate method of surgically repositioning the maxilla to a planned treatment goal and is a very transferable method to assure accurate repositioning of a maxilla in an academic setting

Comparison of macroinvertebrate community traits of riffle and pool habitats from wadeable streams in the Allegheny forest

Aquatic invertebrates are one of the prime groups of organisms used to indicate ecosystem health. This stems from a vast diversity of functions and morphologies present in invertebrate communities; as they are specialized for a variety of microhabitats. Such diversity leads to a wide variation in tolerance to pollutants exhibited by different taxa. Before using these organisms as indicators of aquatic habitat quality, it is important to have a clear understanding of typical community structures present in these ecosystems. This project focuses on contrasts between riffle and pool macroinvertebrate communities from three tributaries in the Allegheny Forest region. Target counts of 300 specimens were randomly subsampled from associated organic material and identified to the genus level. Identified taxa were subsequently enumerated and assigned a functional feeding group trait. Percentage of each functional group was used to compare macroinvertebrate communities between pools and riffles. Ash free dry weight of each sample\u27s organic material was used as a measure of carbon content. Higher percentages of shredders and collector-gatherers are expected to be found in the pools as the deeper, slow-moving water results in a buildup of organic matter in the substrate which can be easily accessed. Contrastingly, riffles are predicted to have a higher percentage of predators and collector-filterers. Invertebrates in these areas are thus more likely to depend on available biota and suspended particulate matter for sustenance. Importance of these functional traits can be taken into account when outlining the ecological parameters of a system as a future goal for this project

Predicted inlet gas temperatures for tungsten fiber reinforced superalloy turbine blades

Tungsten fiber reinforced superalloy composite (TFRS) impingement cooled turbine blade inlet gas temperatures were calculated taking into account material spanwise strength, thermal conductivity, material oxidation resistance, fiber-matrix interaction, and coolant flow. Measured values of TFRS thermal conductivities are presented. Calculations indicate that blades made of 30 volume percent fiber content TFRS having a 12,000 N-m/kg stress-to-density ratio while operating at 40 atmospheres and a 0.06 coolant flow ratio could permit a turbine blade inlet gas temperature of over 1900K. This is more than 150K greater than similar superalloy blades

Floating zone process for drawing small diameter fibers of refractory materials

New process produces controlled purity, very high strength, single crystal fibers of materials with melting points to 4000 C. Process has been used to make single crystal fibers of highly refractory ceramics such as aluminum oxide, titanium carbide and yttrium oxide

The Management of Long Bone Fractures in Birds

This paper will discuss the difficulties and problems in the management of avian fractures. It will deal with both open and closed reduction of long bone fractures

Small high-temperature nuclear reactors for space power

Criticality calculations for small, cylindrical, lithium cooled reactors for space power system

Breaking the Bonds of Blood: The Politics of Family Migration in Europe

Family migration accounts for the majority of migrant movement to the developed world. In response, European states change family migration policy provisions in an attempt to balance national interests with their human rights obligation to respect family life. This dissertation explains variation across European family migration polices and discovers politics is the primary policy determinant. The findings suggest public support for immigration control and radical anti-immigrant parties trumps humanitarian, economic, and demographic concerns when it comes to explaining variance in family migration policy. Indicators of political conservativism also describe variation in labor and family migrant policy, in family immigration and immigrant policies, and in the implementation of “integration from abroad” programs. The results have significant political implications on two fronts. First, immigration policies based on humanitarian principles are fragile to national political maneuvering, suggesting that international law has not obtained significant weight over national interests. Second, the importance of the radical right and anti-immigrant public opinion for family migration policy reveals the vulnerability of rights-based immigration policy to anti-democratic interests. In addition to providing robust findings and practical implications for domestic and international politics, this dissertation contributes to the existing literature in an additional four ways: it examines family migration (which has not been widely distinguished as a unique subject of study); it groups existing theories of immigration policy into an evaluative framework of humanitarian, economic, political, and demographic policy motivators; it uses multivariate analysis to examine general trends across cases; and it uses recent data to examine policy provisions in quantitative models