The CubeSat Astronomy Network is a proposed system of multiple CubeSat spacecraft capable of performing follow-up observations of astronomical targets of interest. The system is intended to serve as a space-borne platform that can complement existing systems utilized for astronomical research by undergraduate and high school students. Much research and development work has been performed to develop model-based system engineering methodologies and products for CubeSat missions, including the Horizon Simulation Framework. The Horizon Simulation Framework enables the development of system models using the Extended Markup Language (XML), and its simulation program can generate system simulations over model-specified timespans. System requirements and constraints, as well as subsystem dependencies and functions, can also be directly specified in these models. Previous work using the framework has been performed to characterize “day-in-the-life” operations for Earth-observing spacecraft. A similar goal is intended for modeling the CubeSat Astronomy Network: simulating mission operations during nominal conditions to validate system and subsystem requirements. By developing this model, system and subsystem requirements derived in the course of preliminary design for the Network can be analyzed, modelled, and evaluated for feasibility. These results can then be used to inform design decisions related to system architecture and concept of operations at the early stages of design, while the models themselves can grow and mature alongside project development and be re-used for future design work.

Space debris has become an increasingly hazardous obstacle to continued spaceflight operations. In an effort to mitigate this problem an investigation of the feasibility of a microsatellite active debris removal system was conducted. Through proposing a novel concept of operation, utilizing a grapple-and-tug system architecture, and by analyzing each resultant mission phase in the frame of a representative example, it was found that microsatellite scale systems are capable of fulfilling the active debris removal mission. Analysis of rendezvous, docking, control and deorbit mission requirements determined that the design of a grapple-and-tug system will be driven by sizing of the propellant required to deorbit the target vehicle. Further sensitivity analysis determined that target altitude and mass are critical factors in determining the capabilities of a microsatellite mission. Preliminary sizing demonstrated that hardware considerations for both satellite core and mission related activities do not impede microsatellite feasibility. Further investigation of microsatellite debris removal missions including detailed design analysis and engineering is suggested.

This paper is focused on customization of induction machine type STM71-4L. The need of optimal mechanical design is presented, to achieve sufficient synchronizing reluctant torque, which will result in rotor synchronization with stator magnetic field. Final mechanical design is suggested after research, which considers influence of the essential rotor dimensions on resulting electromechanical torque. This is provided with usage of finite element method calculation. As a result of the thesis the combination of two basic machines – induction machine and synchronous motor is presented. The measurement on induction motor, and it´s modified versions is presented in following chapters. In the last chapter the results of optimization and measurement are discussed and compared.

In all common hydrostatic pumps, compressibility affects the commutation phases of the displacing chambers, as they switch their connection from/to the inlet to/from the outlet port, leading to pressure peaks, localized cavitation, additional port flow fluctuations and volumetric efficiency reduction. In common pumps, these effects are reduced by proper grooves that realizes gradual port area variation in proximity of these transition regions. This paper presents a method to automatically find the optimal designs of these grooves, taking as reference the case of external gear pumps. The proposed procedure does not assume a specific geometric morphology for the grooves, and it determines the best feasible designs through a multi-objective optimization procedure. A commercial gear pump is used to experimentally demonstrate the potentials of the proposed method, for a particular case aimed at reducing delivery flow oscillations.

Conceptual design optimization (CDO) is a technique proposed for the structured evaluation of different design concepts. Design grammars provide a flexible modular modelling architecture. The model is generated by a compiler based on predefined components and rules. The rules describe the composition of the model; thus, different models can be optimized by the CDO in one run. This allows considering a mission design including the mission analysis and the system design. The combination of a CDO approach with a model based on design grammars is shown for the concept study of a near-Earth asteroid mission. The mission objective is to investigate two asteroids of different kinds. The CDO reveals that a mission concept using two identical spacecrafts flying to one target each is better than a mission concept with one spacecraft flying to two asteroids consecutively.

With the More Electric Aircraft paradigm, commercial commuter aircraft are increasing the size and complexity of electrical power systems by increasing the number of electrical loads. With this increase in complexity comes a need to analyze electrical power systems using new tools. The Hybrid Power System Optimizer (HyPSO) developed by Airbus SAS is a simulator designed to analyze new aircraft power systems. This thesis project will first provide a method to assess the reliability of complex aircraft electrical power systems before and after failure and reconfiguration events. Next, an add-on to HyPSO is developed to integrate the previously developed reliability calculations. Proof-of-concepts including new data visualizations are performed and provided.

The goal of "greener" aviation is one of the main challenges in aircraft design. The target of Europeans "Flightpath 2050'' and IATA is to reduced the net aviation CO2 emission by 75% relative to 2000 and 50% relative to 2005, respectively. Novel unconventional aircraft claim to increase the efficiency and reduce the environmental impact. Designs differing from the conventional tube-low-wing concept are investigated regarding their performance benefit. The employment of a high aspect ratio wing is an effective way to increase the aerodynamic efficiency. However, the long and slender wing structure is more flexible and thus more prone to aeroelastic effects. Critical phenomena, such as flutter and limit-cycle oscillation are more likely to drive the design. Therefore it is important to assess the interdependence of aerodynamic and structural forces. The effects of the wings flexibility can affect the design and off-design performance, possibly jeopardizing the intended efficiency benefit. To evaluate the different disciplines involved in aircraft design, a multi-disciplinary design optimization environment offers the required tools. While computationally demanding, the obtained solution is more efficient if the disciplines are assessed simultaneously. Equipped with low- and high-fidelity assessments, aircraft performance can be predicted at the preliminary design stage, while mitigating some computational expenses. To further reduce the computational burden, adaptive surrogate modelling approaches can be employed, requiring less computational evaluations while efficiently guiding the optimization process towards improved designs. Considering surrogate models for expensive physics based objective and constraint functions bears the disadvantage of more uncertainty in the models. Thus, a new technique is proposed to utilizing the probability of feasibility for the constraints in combination with a transformed normalized objective function to address the uncertainty consideration. The approach is assessed via mathematical test functions and an engineering application and compared against established methods. The results suggests an applicability of the method, with further improvements to be examined. Limitations are revealed regarding local optima and convergence. Further, the degree of maturity does not yet suffice for industrial applications. In a multi-disciplinary design optimization of a high aspect ratio wing aircraft and a strut braced wing aircraft a more classical EGO approach was therefore the choice of approach. The configurations were optimized towards a multi-objective, blending manufacturing and operational costs. Towards cost efficient evaluations, investigations were performed to incorporate high-fidelity assessments, yet limiting their number by reducing active constraints. Driven by aero-structural and aeroelastic constraints, the novel designs could improve the performance satisfactory. / Graduate

While vertical takeoff and landing aircraft show promise for urban air transport, distributed electric propulsion on existing aircraft may offer an immediately implementable alternative. Dis- tributed electric propulsion has the potential of increasing the aircraft thrust-to-weight ratio and lift coefficient high enough to enable takeoff distances of less than 100 meters. While fuel based propulsion technologies generally increase in specific power with increasing size, electric propul- sion typically can be decreased in size without a decrease in specific power. The smaller but highly power-dense propulsion units enable alternative designs including many small units, optionally powered units, and vectored thrust from the propulsion units, which can all contribute to better runway performance, decreased noise, adequate cruise speed, and adequate range. This concep- tual study explores a retrofit of continuously powered, invariant along the wingspan, open bladed electric propulsion units. To model and explore the design space we used a set of validated models including a blade element momentum method, a vortex lattice method, linear beam finite element analysis, classical laminate theory, composite failure, empirically-based blade noise modeling, mo- tor mass and motor controller empirical mass models, and nonlinear gradient-based optimization. We found that while satisfying aerodynamic, aerostructural, noise, and system constraints, a fully blown wing with 16 propellers could reduce the takeoff distance by over 50% when compared to the optimal 2 propeller case. This resulted in a conceptual minimum takeoff distance of 20.5 meters to clear a 50 ft (15.24 m) obstacle. We also found that when decreasing the allowable noise to 60 dBa, the fully blown 8 propeller case performed the best with a 43% reduction in takeoff distance compared to the optimal 2 propeller case. This resulted in a noise-restricted conceptual minimum takeoff distance of 95 meters.Takeoff distances of this length could open up thousands of potential urban runway locations to make a retrofit distributed electric aircraft an immediately implementable solution to the urban air transport challenge.

Inserts are a crucial part of household and industrial furniture. These small plastic parts which often go unnoticed to the naked eye perform crucial functions like providing a base for the furniture, leveling the furniture, safeguarding the user from edges of the tubes used and providing an aesthetic finish. The inserts have a wing like structure on the exterior which enables them to be inserted and securely held in the tubes. The inserts are assembled into the pipes manually or through machines. The force required to install these inserts in the tube is called a push-in force whereas a pull-out force is the force required for removal of the is called a pull-out force. These forces are experienced by someone who assembles the furniture together. Thus, these forces directly define the ease with which the furniture can be assembled. In the first part of the present thesis, these push-in and pull-out forces are predicted using finite element simulations. These finite element simulations were validated by performing physical assembly and disassembly experiments on these inserts. It was found that the finite element simulations of the insert are useful tool in predicting the push-in forces with a high accuracy.   These push-in and pull-out forces for a single insert vary by 2-5 times when the dimensional variations in the tube are considered. The dimensional variations can be a result of the manufacturing processes from which these tubes are produced. The maximum and minimum dimensions that the tube can have are defined by the maximum material condition (MMC) and the least material condition (LMC). To reduce the variation in push-in and pull out forces, a stricter tolerance control can be applied to the manufacturing process. To avoid this cost while having a lower variation in the push-in and pull out forces, the design of the insert was modified. To achieve this enhanced design of the insert, a metamodel based optimization technique was used in the second part of the thesis. For this optimization, the geometrical parameters - wing height, wing diameter and stem thickness the of the insert were identified as the crucial factors which govern the assembly/disassembly forces. The identification of these parameters was done through a design of experiments. These parameters were then varied simultaneously in a metamodel based optimization which had an objective to minimize the variation in forces observed for an insert when the maximum material condition and the least material conditions are considered. The result for the enhanced design of the insert was then stated in terms of the ratio of these identified parameters. The modified design of the insert not only enables the manufacturer to have better performance, but also reduces the amount of plastic material required for manufacturing of the insert.

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