Thesis (M.S)--Ohio University, March, 2005. / Includes bibliographical references (p. 94-96)

Thesis (M.S)--Ohio University, March, 2005. / Title from PDF t.p. Includes bibliographical references (p. 94-96)

Thesis (M.Sc.Eng.) / Guided airdrop systems lacking propulsion may be adversely affected by high winds. Strong winds encountered during Draper Laboratory flight testing prevented lightweight parafoil systems from landing accurately. This thesis introduces and compares multiple guidance strategies designed to address high wind scenarios in cases of differing wind knowledge fidelity. The algorithms presented significantly improve performance in high tailwind and shifting wind scenarios without compromising miss accuracy in standard wind conditions. This adds additional capability to parafoil guidance by substantially increasing the conditions under which accurate landings are possible.

Orientador: Valério Antonio Pamplona Salomon / Banca: Fernando Augusto Silva Marins / Banca: Mischel Carmem Neyra Belderrain / Resumo: A Terceirização está relacionada com a forma na qual uma organização trata os seus fornecedores mediante um contrato de negócio, onde uma atividade específica é acordada para ser feita. Assim em todo o processo produtivo é necessário medir o desempenho, mesmo sendo uma atividade relacionada a um serviço terceirizado. Esta pesquisa apresentou uma aplicação baseada nos métodos DEA (Data Envelopment Analysis) e AHP (Analytic Hierarchy Process), cujo objetivo foi o de avaliar a eficiência de empresas terceirizadas na indústria aeronáutica, além de propor uma avaliação da relação entre as variáveis de entrada e saída do processo com a medida de eficiência. Para as saídas do processo (outputs) foram considerados os critérios da Qualidade, do Prazo e do Custo, que foram quantificados pelo AHP para a matriz DEA. Como input foi utilizado o número de documentos técnicos recebidos pelas empresas terceirizadas. Os indicadores e critérios foram escolhidos mediante a aplicação de um questionário junto aos especialistas do processo de publicações técnicas de peças de reposição. A proposta de aplicação do modelo foi apresentada e validada junto a este grupo de profissionais. Os resultados obtidos com o software SIAD foram considerados satisfatórios. A análise da relação entre a redução no número de saídas, e a variação nos valores de eficiência foi feita, e com isto foi possível agrupar as empresas passíveis de investimento na melhoria de seus processos. / Abstract: Outsourcing is related to the action which an organization deals with its suppliers through a kind of business contract where a specific activity or service has been hired to be made. This research proposed a model which was based in the methods DEA and AHP, and its purpose was to evaluate the efficiency of outsourced companies in the aeronautical industry.It also proposed an evaluation in the relation between the variables of the process and the value obtained for the effiiency. The criteria of Quality, Time and Cost were considered the outputs of the process, and those criteria were quantified by AHP for DEA matrix.The number of technical documents received by those outsorced companies were considered the input of the process. The criteria and its indicators were chosen with a questionnaire which was apllied in a group of specialists of spare parts technical publications. The proposal of the model was showed and it was validated by this same group of specialists. The results obtained with the software SIAD were considered satisfactory. The analysis of the relation between the reduction in the number of outputs and the variation in the value of the efficiency was done and it was possible to separate the companies in groups that were considered able to receive an investment to improve their process. / Mestre

Made available in DSpace on 2014-06-11T19:30:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-01Bitstream added on 2014-06-13T19:18:32Z : No. of bitstreams: 1 ferreirafilho_ajca_me_guara.pdf: 570720 bytes, checksum: b52bd3fa438501d3e9425935b342457a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A Terceirização está relacionada com a forma na qual uma organização trata os seus fornecedores mediante um contrato de negócio, onde uma atividade específica é acordada para ser feita. Assim em todo o processo produtivo é necessário medir o desempenho, mesmo sendo uma atividade relacionada a um serviço terceirizado. Esta pesquisa apresentou uma aplicação baseada nos métodos DEA (Data Envelopment Analysis) e AHP (Analytic Hierarchy Process), cujo objetivo foi o de avaliar a eficiência de empresas terceirizadas na indústria aeronáutica, além de propor uma avaliação da relação entre as variáveis de entrada e saída do processo com a medida de eficiência. Para as saídas do processo (outputs) foram considerados os critérios da Qualidade, do Prazo e do Custo, que foram quantificados pelo AHP para a matriz DEA. Como input foi utilizado o número de documentos técnicos recebidos pelas empresas terceirizadas. Os indicadores e critérios foram escolhidos mediante a aplicação de um questionário junto aos especialistas do processo de publicações técnicas de peças de reposição. A proposta de aplicação do modelo foi apresentada e validada junto a este grupo de profissionais. Os resultados obtidos com o software SIAD foram considerados satisfatórios. A análise da relação entre a redução no número de saídas, e a variação nos valores de eficiência foi feita, e com isto foi possível agrupar as empresas passíveis de investimento na melhoria de seus processos. / Outsourcing is related to the action which an organization deals with its suppliers through a kind of business contract where a specific activity or service has been hired to be made. This research proposed a model which was based in the methods DEA and AHP, and its purpose was to evaluate the efficiency of outsourced companies in the aeronautical industry.It also proposed an evaluation in the relation between the variables of the process and the value obtained for the effiiency. The criteria of Quality, Time and Cost were considered the outputs of the process, and those criteria were quantified by AHP for DEA matrix.The number of technical documents received by those outsorced companies were considered the input of the process. The criteria and its indicators were chosen with a questionnaire which was apllied in a group of specialists of spare parts technical publications. The proposal of the model was showed and it was validated by this same group of specialists. The results obtained with the software SIAD were considered satisfactory. The analysis of the relation between the reduction in the number of outputs and the variation in the value of the efficiency was done and it was possible to separate the companies in groups that were considered able to receive an investment to improve their process.

Construction waste minimization and management plays an efficient role in achieving sustainability by providing appropriate consideration to the environment, community, and social conditions by delivering built assets. The construction industry has a significant effect on the environment in terms of resource consumption and waste production. Recent statistics published by the UK Government disclose that the construction and demolition sector generates approximately 32% of the total waste in the UK, which is three times more than the waste generated by all households combined. Concrete has been a leading construction material for more than a century. However, current and on-going studies in the field of construction waste minimization and management mostly focus on general waste management or examine one specific method of waste minimization. While only a limited number of studies have been conducted to examine on-site concrete waste minimization, the literature reveals that research in this context is required. This research aimed to propose an on-site concrete waste minimisation framework (OCWMF) for construction projects, which could potentially be applicable and achievable in Iran. In this pursuit, six objectuves were determined to guide the research, which are: to identify the common methods on OCWM in the UK as a successful pattern in WM; to rank OCWM methods in UK; to rank OCWM methods in Iran; to identify the differences between common methods of OCWM in the UK and Iran and explore the possible causes of these differences; and to investigate the causes of differences in the favoured methods in the UK and the favoured methods in Iran. Finally, the last objective was to propose a framework for Iran. Both quantitative and qualitative strategies as well as a combination of qualitative and quantitative strategies were adopted for this research. Data was collected through face-to-face semi-structured interviews in the UK (N=5), a self-administered postal questionnaire survey in the UK (N=196 distributed, N=73 received), a self-administered postal questionnaire survey in Iran (N=196 distributed, N=110 received), and face-to-face semi-structured interviews in Iran (N=10). Interviewees were project managers, site superintendents, consultants, and engineers selected from the top 100 contractor companies and the top 100 consultant companies in the UK and in Iram. The questionnaire questions were developed on the findings of the literature review and the semi-structured interviews in the UK. Then, to examine the outcomes of interviews in Iran, three case studies in Iran was observed. Finally, emanating from study results, an OCWMF was developed and refined using discussions (N=2), a questionnaire (N=6), and interviews (N=7). Key findings that emerged from the study include: legislation and regulations in the UK are the main drivers for construction waste reduction; governmental initiatives in reducing waste, use of pre-fabricated building components, and education and training are the most recommended OCWM methods in the UK in terms of overall worthiness or spending to create savings or minimize waste; governmental incentives to reduce waste, education and training, and purchase management are the most recommended methods in Iran; the main differences between proposed OCWM methods in Iran and in the UK are in the use of pre-fabricated concrete elements (PCEs) and ready-mix concrete; the cost of using PCEs in the main cause of difference in methods between the countries; and the consultants and contractors involved in the case study were not interested in using PCEs in their projects due to the high costs involved despite the significant reduction in waste when this method is used. In conclusion, the framework proposed various remedies that could potentially be used for improving OCWM in Iran. This study has also made some recommendations for the industry, policy makers, and for further research. The content should be of interest to contractors, clients, and engineers.

The use of Unmanned Aerial Vehicles (UAVs) are rapidly expanding and taking on new roles in the military. In the area of training and targeting vehicles, control systems are expanding the functionality of UAVs beyond their initially designed purpose. Aeromech Engineering’s NXT UAV is a high speed target drone that is intended to simulate a small aircraft threat. However, in the interest of increasing functionality, enabling NXT to accomplish wings level skidding turns provides the basis for a UAV that can simulate a threat from a missile. Research was conducted to investigate the aerodynamic and performance characteristics of a winged vehicle performing high acceleration skidding turns. Initially, a linear model was developed using small disturbance theory. The model was further improved by developing a six degree of freedom simulation. A controller using four loop closures and utilizing both rudder and aileron for control was developed. Any outside guidance system that navigates using a heading command can easily be integrated into this controller design. Simulations show this controller enables the NXT UAV to accomplish up to 3 G wings level skidding turns. Further testing, showed that the controller was able to tolerate significant turbulence, sensor noise, loop failures and changes within the plant dynamics. This research shows how it is possible for a winged UAV to easily maneuver using wings level skid turns.

Aluminum alloys are used on aerospace vehicles due to their high strength-to-weight ratio, formability and machinability. However, they become vulnerable to stress corrosion cracking (SCC) during their service life. SCC is primarily caused by the material's stress condition, a suitable corrosive environment and material susceptibility. It is also influenced by a mixture of electrochemical, mechanical, and chemical factors. Due to the complexity of SCC, tools with better resolution and sensitivity are needed to better understand the impact and interaction of the contributing factors. A vast amount of research has been done to study SCC behavior, but the scale of characterization must be reduced to elucidate the key initiation mechanisms. In this work, it is shown that SCC initiation was detected early via micro-digital image correlation (micro-DIC) prior to the crack being discernible in microscopy images. The initial effort to monitor stress corrosion cracking in AA7075-T6 involved using a pixel resolution of 3.825 microns/pixel, frame rate of 10-15 min/image and an airbrush nozzle diameter of 0.3 mm for the speckle pattern, which led to the detection of crack initiation at 98% failure load. By using a pixel resolution that is 6 times smaller, a frame rate of up to 60 times less time per image, and an airbrush nozzle that is 2 times smaller, the first observation of strain concentration marking the eventual failure region of the AA7075-T6 sample was detected as early as 58% failure load. When the micro-DIC technique was applied to study SCC behavior in additively manufactured AlSi10Mg, the first observation of localized strain marking the eventual failure region of the sample was detected at 78% failure load. X-ray synchrotron tomography was used to qualitatively assess the hydrogen bubble and precipitate formation and to quantitatively assess the post initiation crack growth in AA7075-T651. With improved micro-DIC parameters and correlation with experimental outcomes from x-ray synchrotron tomography, multiple factors contributing to SCC can be assessed to better understand the mechanisms of SCC initiation. Correlations of material exposure time and load with SCC initiation can provide data for developing corrosion control strategies and new and improved alloys or heat treatment, as well as understanding SCC behavior in alloys made through unconventional means, such as additive manufacturing. The impact of this work lies in the life extension of alloys and greater reusability and fatigue life extension of aerospace vehicles.

This these explores automatic modulation recognition as applied to PCM/FM, SOQPSK- TG and ARTM CPM. It found that the likelihood based approach is intractable. The statistical features of the amplitude, phase and frequency are ineffective at distinguishing these modulation types. A method based on the phase changes between symbols is developed and shows that as long as symbol timing is established, this method can effectively distinguish PCM/FM, SOQPSK-TG and ARTM CPM for signal-to-noise ratios above 30 dB. Another method, the Bianchi-Loubaton- Sirven technique, was able to distinguish PCM/FM and SOQPSK-TG but was unable to distinguish ARTM CPM. A happy byproduct of this classification algorithm is a reasonably accurate estimate of the bit rate. Simulation results show that this classifier works essentially error-free for signal- to-noise ratios above 20 dB and for sufficiently high resolution in the search algorithms required by the maximizations.

The amplitude fluctuation induced by a spinning missile acts as a disturbance on tracking schemes that use sequential lobing (e.g., conscan). In addition, if a tracking system converts from S-band to C-band, the beamwidth is narrower and the wrap-around antenna on the missile requires more patches, and so the margin of error for tracking decreases. Tracking performance is simulated with a spinning missile with ballistic and fly-by trajectories while running at C-band. The spinning missile causes a periodic component in the pointing error, and when the scan frequency is an integer multiple of the roll rate, several tracking schemes lose track of the target. Remedial techniques are discussed, including increasing the scan frequency and using simultaneous (monopulse) tracking rather than sequential lobing.