Development and Testing of an Inflatable, Rigidizable Space Structure Experiment

Many recent space technology concepts require large space structures such as solar arrays and large aperture antennas; however, tight constraints on payload mass and volume often preclude their launch. Employing inflatable, rigidizable structures can reduce mass and volume while providing sufficient packing flexibility and structural stiffness. AFIT has developed RIGEX to flight-test this type of structure. RIGEX will test the deployment and structural characteristics of three thermoplastic composite Sub-Tg tubes. Once launched on the Space Shuttle in 2007, the spaceflight results will be compared to lab data to validate on-orbit reliability and ground test methods. This paper documents three main RIGEX development items: the Space Shuttle integration process, random vibration testing of the oven assembly, and development and application of the RIGEX structural model. The RIGEX launch integration process has been laid out and the first milestones, the RIGEX Preliminary Design Review and Phase 0/I Safety Review, were successfully completed in September 2005. Subsequently, random vibration testing of the prototype RIGEX oven assembly validated its structural integrity. Furthermore, a RIGEX structural model was developed using the finite element approach and NX Nastran for FEMAP software. The RIGEX FEM produced a first natural frequency of 242 Hz, meeting the NASA requirement with a margin of over 140 Hz. Overall, the RIGEX structural design has rapidly matured, meeting all NASA requirements thus far

Advanced Gas Turbine (AGT) power-train system development

Technical work on the design and component testing of a 74.5 kW (100 hp) advanced automotive gas turbine is described. Selected component ceramic component design, and procurement were tested. Compressor tests of a modified rotor showed high speed performance improvement over previous rotor designs; efficiency improved by 2.5%, corrected flow by 4.6%, and pressure ratio by 11.6% at 100% speed. The aerodynamic design is completed for both the gasifier and power turbines. Ceramic (silicon carbide) gasifier rotors were spin tested to failure. Improving strengths is indicated by burst speeds and the group of five rotors failed at speeds between 104% and 116% of engine rated speed. The emission results from combustor testing showed NOx levels to be nearly one order of magnitude lower than with previous designs. A one piece ceramic exhaust duct/regenerator seal platform is designed with acceptable low stress levels

Apparent facilitation of an invasive mealybug by an invasive ant

Summary: In the southeast United States, the invasive ant Solenopsis invicta is known to derive important carbohydrate (honeydew) resources from mealybugs utilizing grasses. Most important appears to be an invasive mealybug, Antonina graminis. We studied whether this mealybug and a similar native species also benefit from association with S. invicta. We found that mealybug occurrence increases significantly with increasing proximity to S. invicta mounds, suggesting that mealybugs benefit as well. Mutual benefits derived by S. invicta and A. graminis are consistent with a hypothesis proposing that associations among invasive species can be important in their success at introduced location

Application of knowledge network analysis to identify knowledge sharing bottlenecks at an engineering firm

The knowledge of an organization’s employees is a valuable asset. Therefore organizations should ensure that their employees share their knowledge among each other. Knowledge exchanges between employees can be modelled as a network of relationships. To study these networks we have developed the Knowledge Network Analysis technique, which is based on Social Network Analysis and supports visual as well as quantitative analysis of knowledge networks. The goal of this technique is to identify bottlenecks in knowledge sharing in a particular knowledge area. In this paper we present the results of the application of Knowledge Network Analysis in an explorative case study. The goal of the case study is to explore the usefulness of Knowledge Network Analysis in identifying knowledge sharing bottlenecks. The case study results in a deeper understanding of how to translate the characteristics of the knowledge network and the employees in this network to the context of the case study organization. Moreover, the case study results have also been used to formulate recommendations to improve knowledge sharing at the case study organization

Indigenous entrepreneurship in timber furniture manufacturing: The Gumatj venture in Northern Australia

Despite commitment by the Australian Government to improve the economic independence of Indigenous people Aboriginals and Torres Strait Islanders they are the most socio economic disadvantaged group relative to other Australians. This commitment manifests in the four main strands of; 1) welfare, 2) installation of the Community Development Employment Projects (CDEP) scheme, 3) legislation enabling Traditional Land Owners and miners to negotiate agreements for training and employment of Indigenous people, and 4) programmes to encourage Indigenous entrepreneurship. This paper reports an Australian Indigenous entrepreneurial business (furniture making) initiated by the Gumatj clan of the Yolngu people in East Arnhem Land in the Northern Territory (NT) of Australia. These Indigenous people are employed in timber milling and transporting the milled timber to Gunyangara on the Gove Peninsula where it is dried and used to make furniture. Overcoming the literature documented barriers to Australian Indigenous entrepreneurship compelled the Gumatj to develop a business model with potential to foster pathways for other Indigenous small business endeavours

Advanced Gas Turbine (AGT): Power-train system development

Technical work on the design and effort leading to the testing of a 74.5 kW (100 hp) automotive gas turbine is described. The general effort was concentrated on building an engine for test starting in July. The buildup progressed with only routine problems and the engine was delivered to the test stand 9 July. In addition to the engine build effort, work continued in selected component areas. Ceramic turbine parts were built and tested. Burst tests of ceramic rotors show strengths are approaching that achieved in test bars; proof testing is required for acceptable strength ceramic vanes. Over 25 hours was accumulated on the combustor rig in three test modes: pilot nozzle only, start nozzle, and main nozzle operation. Satisfactory ignition was achieved for a wide range of starting speeds and the lean blowout limit was as low as 0.06 kg/b (0.14 lb/hr). Lean blowout was more a function of nozzle atomization than fuel/air ratio. A variety of cycle points were tested. Transition from start nozzle flow to main nozzle flow was done manually without difficulty. Regenerator parts were qualification tested without incident and the parts were assembled on schedule. Rig based performance matched first build requirements. Repeated failures in the harmonic drive gearbox during rig testing resulted in that concept being abandoned for an alternate scheme

Building sustainability in an Indigenous family owned SME in northern Australia: Overcoming operational barriers in a housing construction venture

Identifying pathways for small to medium sized enterprises (SMEs), as potential entrants to the international market place, encourages evalutation how entrepreneurial activity can overcome encountered barriers to economic development. In an expression of commitment to improving the socio economic welfare of Indigenous people the Australian Government is encouraging Aboriginal involvement in entrepreneurial ventures, and integrating this notion in a local housing construction business has potential to improve the persistent poor living conditions in remote Australian Aboriginal communities. This paper describes an accomodation building programme initiated by the Yolngu people of East Arnhem Land of Australia, and with illustrations shows location and achivements. Revealing how the literature specified barriers to Australian Indigenous entrepreneurship were overcome provides a pathway worthy of consideration by rural Indigenous communities intending to engage in entrepreneurship, with vision to extent the life cycle of the firm into international markets

Importance of Atomic Charge Concepts in Empirical Force Fields: The SCALCHA Approach to Obtaining Atomic Charges

A general, exactly defined and simple method to obtain the parameters for empirical force fields, as applied in molecular dynamics simulations, is of great interest today. Electrostatic interactions play a very important role in molecular structures. Therefore, there is a need for a method to determine atomic charges for all molecules of biological relevance that can be used in the current monopole approach. We introduce a general, determined and simple method to project atomic charges, for example from quantum mechanical calculations, onto the existing empirical force fields