Continuous fiber thermoplastic prepreg

A pultrusion machine employing a corrugated impregnator vessel to immerse multiple, continuous strand, fiber tow in an impregnating material, and an adjustable metered exit orifice for the impregnator vessel to control the quantity of impregnating material retained by the impregnated fibers, is provided. An adjustable height insert retains transverse rod elements within each depression of the corrugated vessel to maintain the individual fiber tows spread and in contact with the vessel bottom. A series of elongated heating dies, transversely disposed on the pultrusion machine and having flat heating surfaces with radiused edges, ensure adequate temperature exposed dwell time and exert adequate pressure on the impregnated fiber tows, to provide the desired thickness and fiber/resin ratio in the prepreg formed. The prepreg passing through the pulling mechanism is wound on a suitable take-up spool for subsequent use. A formula is derived for determining the cross sectional area opening of the metering device. A modification in the heating die system employs a heated nip roller in lieu of one of the pressure applying flat dies

Paper Session II-B - U.S. Launch Site Processing of Space Station Hardware

There are many challenges to overall planning and management for processing Space Station hardware at the Kennedy Space Center (KSC). Presently, as requirements are being defined for processing Space Station hardware at the Kennedy Space Center, there are many challenges trying to develop ground support equipment, facilities, integrated schedules, plans and processes in parallel with hardware design and development. The Integrated Product Teams and Analysis Integration Teams at the Kennedy Space Center have met the challenges presented by budgetary cuts, manifest changes and new or changing requirements. The Space Station Processing Facility construction is completed. The facility systems are being installed and activated. Kennedy Space Center personnel are working well with the various Launch Package/Stage teams, defining launch site requirements. Kennedy Space Center supplied support equipment is in various of stages of design, fabrication and activation. The Test, Control and Monitor System has undergone a major change in design direction. Management of this entire process brings about unique challenges. Only 20 months away from the first U.S. launched Space Station element, the Space Station Program is well into defining launch site requirements and their implementation. An examination of the organizations and processes involved reveal the complexity of requirements from the Prime Contractor, International Partners/Participant and NASA that must be integrated to provide successful hardware processing at the launch site

A study of the relationships between community power structures, school board types, superintendent leadership styles and the impact on student achievement in Oklahoma.

This study was designed to examine the degree to which relationships of community power structures, school board behavior types and superintendent leadership styles exist in Oklahoma public schools. The study also explored the impact these relationships have on superintendent tenure and student achievement in Oklahoma. The study is based on the 1971 research of McCarty and Ramsey, with follow up studies by Hess (1994), Smith (1998) and Lere (2004). The study is a descriptive inferential study using the results of surveys mailed to all public school superintendents and school board presidents in Oklahoma. The questionnaire was originally designed by Hess in 1994 for use in Wisconsin and modified by Smith in 1998 for use in North Carolina. The survey sought to determine if the four theoretical categories of community power structures, school board types and superintendent leadership styles exist in Oklahoma school districts and the impact they have on student achievement. In addition, selected economic, social, political and demographic variables were examined along with district API scores for possible affects on the relationship types and student achievement.There was a good (53%) return from the superintendents, but a little weaker (24%) return rate by the school board presidents. The return rate of paired districts (92, 17%) allows some limited inferred predictions. From the paired responses the prediction can be made that relationship types and demographics have some impact on student achievement in Oklahoma. It can also be assumed that the combination of the two will likewise have an impact on student achievement. The data revealed evidence that all categories of community power structures, school board types and superintendent leadership styles existed in Oklahoma school districts. This follows and supports prior research indicating a substantial relationship exists between leadership and student achievement. It was also observed that demographics have an impact on the relationship between superintendents and school boards as well as an impact on student achievement. Also discussed are the implications for a need of staff development programs for superintendents and school board presidents and possible need for future studies

Comparison of flexural properties of aramid-reinforced pultrusions having varied matrices, pretreatments and postcures

Aramid-reinforced composite materials of equal fiber volume and varied polymer thermoset matrices were pultruded and flexurally tested to failure. The objective was to improve the flexural properties of aramid-reinforced pultrusions. Pultrusions of both sized and unsized aramid fiber with four different resin systems were compared to determine the effects of sizing compounds and postcuring on flexural strength, fiber wettability, and fiber-to-resin interface bonding. Improvements in flexural strength resulting from pretreatments with the sizing solutions used were marginal. The most significant improvements in flexural properties resulted from postcuring. Flexural strengths ranged from a low of 39,647 psi (273MPa) to a high of 80,390 psi (554 MPa), an overall increase of 103 percent. The fact that postcuring improved the flexural properties of the pultrusions of the four resin systems indicates that a full cure did not occur in any of the resin systems during the pultrusion process. The increased flexural strengths of the polyester and vinyl ester pultrusions were the most surprising. The four resin systems examined were Interplastic Corporation VE 8300 vinyl ester, Ashland Chemical Company Aropol 7430 Polyester, and Shell Chemical Company Epon 9302 and Epon 9310 epoxides

Potential for on-orbit manufacture of large space structures using the pultrusion process

On-orbit manufacture of lightweight, high-strength, advanced-composite structures using the pultrusion process is proposed. This process is adaptable to a zero-gravity environment by using preimpregnated graphite-fiber reinforcement systems. The reinforcement material is preimpregnated with a high-performance thermoplastic resin at a ground station, is coiled on spools for compact storage, and is transported into Earth orbit. A pultrusion machine is installed in the Shuttle cargo bay from which very long lengths of the desired structure is fabricated on-orbit. Potential structural profiles include rods, angles, channels, hat sections, tubes, honeycomb-cored panels, and T, H, and I beams. A potential pultrudable thermoplastic/graphite composite material is presented as a model for determining the effect on Earth-to-orbit package density of an on-orbit manufacture, the package density is increased by 132 percent, and payload volume requirement is decreased by 56.3 percent. The fabrication method has the potential for on-orbit manufacture of structural members for space platforms, large space antennas, and long tethers

Pre-Spawning Migration of Channel Catfish into Three Warmwater Tributaries-Effects of a Cold Tailwater

Spring migrations of channel catfish (Ictalurus punctatus) into the Kings, Mulberry and Buffalo rivers, Arkansas, were compared to determine adult catfish migration into a warm water river that flows into a cold tailwater. The Buffalo River flows into a cold tailwater reach of the White River and supports a sparse channel catfish population compared to similar rivers in the region that do not flow into cold tailwaters. This is an important factor because many recent studies have demonstrated that channel catfish make pre-spawning migrations into tributary streams and may contribute significantly to tributary populations. To assess channel catfish migration, hoop nets were deployed at the confluence of the three rivers and fished continuously from 29 March to 22 April1992, with total catches used as an index of the relative number of fish migrating into each river. Movements of channel catfish into the three rivers were observed throughout April; however, the relative number migrating into the Buffalo River (n=33) was significantly less than the Kings (n=169) or Mulberry (n=263) Rivers. Water temperature differed significantly between the White and Buffalo Rivers during the sampling period, but did not differ between the Kings or Mulberry, and their respective confluence. Although cold, White River tailwaters do not totally inhibit overwintering and migration of adult channel catfish into the Buffalo River, reduced numbers of migratory catfish may partially account for the river\u27s low reproductive output and sparse adult population

Conditioning of Sandhill Cranes During Fall Migration

Body mass of adult female and male sandhill cranes (Grus canadensis) increased an average of 17 and 20%, respectively, from early September to late October on staging areas in central North Dakota and varied by year. Increases in body mass averaged 550 and 681 g among female and male G. c. canadensis, respectively, and 616 and 836 g among female and male G. c. rowani. Adult and juvenile G. c. rowani were lean at arrival, averaging 177 and 83 g of fat, respectively, and fat reserves increased to 677 and 482 g by mid-October. Fat-free dry mass increased by 12% among juveniles, reflecting substantial growth, but remained constant among adults. The importance of fall staging areas as conditioning sites for sandhill cranes, annual variation in body mass, and vulnerability of cranes to habitat loss underscore the need to monitor status of fall staging habitat in the northern plains region and to take steps to maintain suitable habitat where necessary

Sequence patches on MAPK surfaces define protein-protein interactions

Redesigning ‘surface patches’ on a mitogen-activated protein kinase can change its interactions with other proteins

Pultrusion Die Assembly

This invention relates generally to pultrusion die assemblies, and more particularly, to a pultrusion die assembly which incorporates a plurality of functions in order to produce a continuous, thin composite fiber reinforced thermoplastic material. The invention is useful for making high performance thermoplastic composite materials in sheets which can be coiled on a spool and stored for further processing