Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, System Design and Management Program, 2018. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 70-71). / The thesis presents the design and analysis process of a bio-inspired 3D printing body armor for neck support and protection. There are numerous examples of the structural skin or body armor among animals that generates both cranial protection and torso support. In this thesis, the mechanical behavior of the natural structure regarding the specific animal subject will be reviewed and studied using bio-inspired, flexible, design-for-manufacturing armor prototypes designed using computational 3D modeling to tackle a particular problem in real-life body protection. The design process will be demonstrated following the design thinking methodology with the emphasis on user empathy and experience design. Analysis of the prototype's flexibility and strength will be investigated to show how morphometry can enhance the architecture of material. And the accessibility will be researched under quantitative testing and qualitative interviews to the potential beneficiary. The thesis will also explore how the computer aid design can be improved based on bio-inspired analysis and potential mechanical testing. The long-term objective is to use bio-inspired design to develop an additive manufacturing technique for product design to accelerate the iteration process and increase product efficiency. / by Lei Xia. / S.M. in Engineering and Management

Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, System Design and Management Program, 2018. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 87-89). / Substituting non-renewable energy for renewable energy plays an important role for our sustainability, which is the common goal for human beings. However, several strategies by governments and companies exist to make this shift, because the priority of each strategy mainly depends on the relative costs and their regulations, which makes this shift complicated. This paper describes a model of the common causal loop diagram and applies it to three cases. Additionally, by building stock and flow model, the future dynamics are simulated by System Dynamics. Based on the casual loop diagram analysis, the renewable shift makes three phases. The first phase is making an ecosystem of renewables initiated by political support or guideline such establishing a low generation cost and making the power grid system flexible enough to accept renewables. The second phase is pushing the energy mix by private investment to capture the economic benefit including reducing electric bills with low-cost renewable energy, the merit of reputation and sustainability of business. The third phase aims at meeting the political target of the energy mix by political strategies, such as tax exemptions, subsidies and obligations for companies. Stock and flow model of System Dynamics is applied for the future of the Japanese renewable shift cases to illustrate which compositions of the casual loop are the key causes for dynamics. At first, the relative cost triggers the renewable shift not only for companies but also for utilities. After that, the difference of the energy mix of a company and its target decides how much the energy mix increases each year. These two factors decide the intensiveness of investment of a company, even though the relative cost is not an internal factor. Also, the capacity mix of a utility deals with the speed of the renewable shift. / by Masahiro Yamada. / S.M. in Engineering and Management

Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, May, 2020 / Cataloged from the official PDF of thesis. / Includes bibliographical references (pages 56-62). / The industrial meat production system has large scale environmental impacts from depleting natural resources such as water and land and emitting dangerous greenhouse gases, while negatively affecting human health. The inefficiencies of converting plant matter into animal meat is particularly pronounced for beef. Despite these effects, demand is on the rise across the world. Over the past five years, new companies have produced sophisticated meat analogues in the form of plant-based and cultured proteins with a value proposition of keeping meat's taste and cost while decreasing environmental impact. Barriers in pricing, technology, and distribution are currently top of mind for businesses competing in this new industry. Through a literature review, this paper investigates another crucial barrier to consumer adoption in psychological meat attachment and cultural food identity. I then propose an experimental study to test the hypothesis that a matched identity frame (i.e. masculine framing) could induce higher willingness to substitute a plant-based meat option for a conventional meat option of a given dish. / by Lara Ortiz-Luis. / M.B.A. / M.B.A. Massachusetts Institute of Technology, Sloan School of Management

Traditional methods for mechatronics design are often based on a sequential approach, where the mechanical structure is designed first, and then fitted with off-the-shelf electric motors, drive electronics, gearheads and sensors. Finally a control system is designed and optimized for the already existing physical system. Such a design method, that doesn’t consider aspects from a control point of view during the design of the physical system, is unlikely to result in a system with optimal control performance. Furthermore, to separately design and optimize each of the physical components will, from a global perspective, generally not result in a system that is optimal from a weight, size or cost perspective. In order to reach the optimal design of an integrated mechatronic system (mechatronic module) it is necessary to treat the system as a whole, considering aspects from all involved engineering domains concurrently. In this thesis such an approach to integrated design of mechatronic servo systems is presented. A design methodology that considers the simultaneous design of the electric machine, gearhead, machine driver and control system, and therefore enables global optimization, has been developed. The target of the design methodology is conceptual design and evaluation. It is assumed that the load to be driven by the servo system is known and well defined, a load profile describing the wanted load motion and the corresponding torque, is required as input. The methodology can then be used to derive the lightest or smallest possible system that can drive the specified load. Furthermore, the control performance is evaluated and optimized, such that the physical system design and the controller design are integrated. The methodology is based on modelling and simulation. Two types of component models have been developed, static and dynamic models. The static models describe relations between the parameters of the physical components, for example a component’s torque rating as function of its size. The static models are based on traditional design rules and are used to optimize the physical parts of the system. The dynamic models describe the behaviour of the components and are used for control system design and performance optimization. The gear ratio is identified to be the most central design variable when designing and optimizing electromechanical servo systems. The gear ratio directly affects the required size of the gearhead, electric machine and the machine driver. But it has also large influences on the system’s control performance. It is concluded that high gear ratios generally are better from a control point of view than low ratios. A consequence of this is that it is possible, without compromising the control performance, to use less expensive (less accurate) sensors and microprocessors in high gear ratio servo systems, while low gear ratio systems require more expensive hardware. It is also concluded that it is essential to include all performance limiting phenomena, linear as well as non-linear, in this type of integrated analysis. Using for example a linearized system description for controller design, means that many of the most important couplings between control system and physical system design are overlooked. / QC 20100816

No description available.

Ground heat storage systems can play an important role for the reduction of green house gases emissions by increasing the exploitation of renewable energy sources and “waste heat” with a consequent diminution of the use of fossil fuels. A ground heat storage consists in an array of vertical boreholes placed in such a way that promotes the mutual thermal interaction between the ground heat exchangers creating the necessary conditions required to effectively store and retrieve heat. Suitable modeling tools for the estimation of the thermal behavior of these systems are very important to build installations yielding economical performance compatible with what expected during the design phase. This thesis aims at giving a contribution in the development of the thermal modeling of borehole heat storage systems. The main objective is introducing in the modeling process a few features that are not usually considered in state of the art models, with the goal of improving the representation of the physical phenomena. These features are the mathematical description of the topology of the borehole heat exchangers network, and the modeling of borehole fields with arbitrarily oriented boreholes. The detailed modeling of the topology of the borehole heat exchangers is approached with a network model. The overall geothermal system is discretized into smaller systems called components. These are linked between each other in a network fashion to establish the logical relations required to describe a given boreholes connections arrangement. The method showed that the combination of a sufficient level of discretization of the system and of a network representation yields respectively the granularity and the flexibility required to describe any borehole field connections configuration. The modeling of non-vertical borehole fields is approached by developing a method for the calculation of g-functions for these configurations. The method is an extension of a recent work done by Cimmino on the computation of g-functions for vertical borehole fields. This modeling technique is based on describing boreholes as sets of stacked finite line sources and on the superposition principle. This approach requires the computation of response factors relative to couples of finite lines. A procedure for the fast computation of these response factors for the case of arbitrarily oriented lines is given. This yields computational performance that guarantees the practical feasibility of the methodology. The last part of the thesis deals with the modeling of the storage system from a broader perspective. The borehole field is considered as part of a larger system constituted by several interacting components (i.e. heat pump, building, etc.). Interactions play a key role in the resulting overall performance of these systems. The analysis of the mutual relations between building envelope and borehole field design is utilized as an example to highlight advantages and challenges of strategies yielding a more integrated design. / <p>QC 20150507</p>

The geometry of the receiver and recuperator in a small-scale open and direct recuperative solar thermal Brayton cycle can be optimised in such a way that the system produces maximum net power output. The purpose of this work was to apply the second law of thermodynamics and entropy generation minimisation to optimise these geometries using an optimisation method. The dynamic trajectory optimisation method was used and off-the-shelf micro-turbines and a range of parabolic dish concentrator diameters were considered. A modified cavity receiver was used in the analysis with an assumed cavity wall construction method of either a circular tube or a rectangular channel. A maximum temperature constraint of 1 200 K was set for the receiver surface temperature. A counterflow plate-type recuperator was considered and the recuperator length was constrained to the length of the radius of the concentrator. Systems producing a steady-state net power output of 2 – 100 kW were analysed. The effect of various conditions, such as wind, receiver inclination and concentrator rim angle on the maximum net power output, and optimum geometry of the system were investigated. Forty-five different micro-turbines and seven concentrator diameters between 6 and 18 metres were considered. Results show the optimum geometries, optimum operating conditions and minimum entropy generation as a function of the system mass flow rate. The optimum receiver tube diameter was relatively large when compared with the receiver size. The optimum counterflow plate-type recuperator channel aspect ratio is a linear function of the optimum system mass flow rate for a constant recuperator height. The optimum recuperator length and optimum NTU are small at small system mass flow rates but increase as the system mass flow rate increases until the length constraint is reached. For the optimised systems with maximum net power output, the solar receiver is the main contributor to the total rate of minimum entropy generation. The contributions from the recuperator, compressor and turbine are next in line. Results show that the irreversibilities were spread throughout the system in such a way that the minimum internal irreversibility rate was almost three times the minimum external irreversibility rate for all optimum system geometries and for different concentrator diameters. For a specific environment and parameters, there exists an optimum receiver and recuperator geometry so that the system can produce maximum net power output. / Dissertation (MEng)--University of Pretoria, 2011. / Mechanical and Aeronautical Engineering / unrestricted

Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, System Design and Management Program, 2018. / Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 121-126). / Airborne wind energy (AWE) technologies have the potential to become a dominant source of clean electricity generation and help humanity reach many of the key sustainable development goals (SDGs) established by the United Nations as part of the 2030 Agenda for Sustainable Development. AWE systems eliminate the need for a tower, large blades and substantial foundations used in modern wind turbines and replace it with a wing (i.e. kite or glider aircraft) tethered to the ground. This technology can reach higher-altitude winds which is an untapped source of clean and highly abundant energy with the potential to power civilization 100 times over. As part of this work, an AWE research platform has been designed and developed based on a concept that emphasizes low-complexity, safety and low-cost. This research platform can be used to evaluate different sensor frameworks, airfoil/tether designs, control systems and optimal operational strategies for AWE systems operating under lift mode. A first-order techno-economic analysis was also performed to assess the cost and technical feasibility of developing a small-scale AWE system for distributed generation applications. In addition to estimating the approximate cost of the system, the analysis also determines the potential power generated by a specific AWE system design operating at a maximum elevation of 152 meters, to comply with existing regulation. The results of the techno-economic analysis suggest that small-scale AWE systems have the potential to produce electricity at a much lower cost than small-wind turbines of the same rated capacity. / by Carlos Emilio Perez Damas. / S.M. in Engineering and Management / S.M.

No description available.

Thermal management is one of many critical tasks in the design of power electronic systems. It has become increasingly important as a result of the introduction of high power density and integrated modules. It has also been realized that higher temperatures do affect reliability due to a variety of physical failure mechanisms that involve thermal stresses and material degradation. Therefore, it is important to consider temperature as design parameter in developing power electronic modules. The NSF Center for Power Electronics System (CPES) at Virginia Tech previously developed a first generation (Gen-I) active Integrated Power Electronics Module (IPEM). This module represents CPES's approach to design a standard power electronic module with low labor and material costs and improved reliability compared to industrial Intelligent Power Modules (IPM). A preliminary Generation II (Gen-II.A) active IPEM was built using embedded power technology, which removes the wire bonds from the Gen-I IPEM. In this module, the three primary heat-generating devices are placed on a direct bonded copper substrate in a multi-chip module format. The overall goal of this research effort was to optimize the thermal performance of this Gen-II.A IPEM. To achieve this goal, a detailed three-dimensional active IPEM was modeled using the thermal-fluid analysis program ESC in I-DEAS to study the thermal performance of the Gen-II.A IPEM. Several design variables including the ceramic material, the ceramic thickness, and the thickness of the heat spreader were modeled to optimize IPEM geometric design and to improve the thermal performance while reducing the footprint. Input variables such as power loss and interface material thicknesses were studied in a sensitivity and uncertainty analysis. Other design constraints such as electrical design and packaging technology were also considered in the thermal optimization of the design. A new active IPEM design named Gen-II.C was achieved with reduced-size and improved thermal and electrical performance. The success of the new design will enable the replacement of discrete components in a front-end DC/DC converter by this standard module with the best thermal and electrical performance. Future improvements can be achieved by replacing the current silicon chip with a higher thermal-conductivity material, such as silicon carbide, as the power density increases, and by, exploring other possible cooling techniques. / Master of Science