Recursos de colección

DSpace at MIT (99.061 recursos)

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Mechanical Engineering - Master's degree

Mostrando recursos 1 - 20 de 3.628

  1. Desalination of brackish groundwater in the United States : minimum energy requirements

    Ahdab, Yvana D
    Water scarcity around the globe has motivated rising interest in desalinating brackish groundwater to meet fresh water demand. Various organizations in the United States have collected more hydrological and chemical data from the growing number of wells. Yet, only one national assessment of groundwater resource distribution and availability has been conducted in the United States since the 1960s, and no national assessment has been conducted on the energy costs required to make brackish groundwater potable. Because the ionic composition of groundwater varies significantly from location to location, unlike seawater, conducting site-specific analyses of the resource across the U.S. is necessary....

  2. Desalination of brackish groundwater in the United States : minimum energy requirements

    Ahdab, Yvana D
    Water scarcity around the globe has motivated rising interest in desalinating brackish groundwater to meet fresh water demand. Various organizations in the United States have collected more hydrological and chemical data from the growing number of wells. Yet, only one national assessment of groundwater resource distribution and availability has been conducted in the United States since the 1960s, and no national assessment has been conducted on the energy costs required to make brackish groundwater potable. Because the ionic composition of groundwater varies significantly from location to location, unlike seawater, conducting site-specific analyses of the resource across the U.S. is necessary....

  3. Design and control of miniature air-and-ground vehicles

    Araki, Minoru Brandon
    The ability to both fly and drive is a superpower that few robots have. This thesis describes the design and control of two miniature air-and-ground vehicles, the "Flying Monkey" and the "Flying Car." The Flying Monkey was developed to demonstrate the viability and utility of miniature air-and-ground vehicles. The final design weighs 30g yet is capable of crawling, grasping, and flying. It features a novel crawling and grasping mechanism that consists of 66 linkages yet weighs only 5.1 grams. Although the crawler is capable of only forward and backward motion, we designed a controller that uses the yaw torque of...

  4. Design and control of miniature air-and-ground vehicles

    Araki, Minoru Brandon
    The ability to both fly and drive is a superpower that few robots have. This thesis describes the design and control of two miniature air-and-ground vehicles, the "Flying Monkey" and the "Flying Car." The Flying Monkey was developed to demonstrate the viability and utility of miniature air-and-ground vehicles. The final design weighs 30g yet is capable of crawling, grasping, and flying. It features a novel crawling and grasping mechanism that consists of 66 linkages yet weighs only 5.1 grams. Although the crawler is capable of only forward and backward motion, we designed a controller that uses the yaw torque of...

  5. Hybrid inkjet and direct-write multi-material additive manufacturing

    Bandiera, Nicholas Graham
    Recently there has been a trend towards combining multiple forms of additive manufacturing together for increased functionality, freedom and efficiency. In this work, two forms of multiple-material additive manufacturing technologies - inkjet and direct-ink writing - are combined in a hybrid system. Several advantages are realized due to the increased material library and geometric freedom as a result of new printing modalities. Initially, models of each process are reviewed and the processes are evaluated for compatibility. Then, the precision machine design of a passively-indexed, carousel-style, syringe tool holder is completed. An error budget employing Homogeneous Transformation Matrices was maintained to...

  6. Hybrid inkjet and direct-write multi-material additive manufacturing

    Bandiera, Nicholas Graham
    Recently there has been a trend towards combining multiple forms of additive manufacturing together for increased functionality, freedom and efficiency. In this work, two forms of multiple-material additive manufacturing technologies - inkjet and direct-ink writing - are combined in a hybrid system. Several advantages are realized due to the increased material library and geometric freedom as a result of new printing modalities. Initially, models of each process are reviewed and the processes are evaluated for compatibility. Then, the precision machine design of a passively-indexed, carousel-style, syringe tool holder is completed. An error budget employing Homogeneous Transformation Matrices was maintained to...

  7. Design, development, and field-testing of a cost-optimized village-scale, photovoltaic-powered, electrodialysis reversal water desalination system for rural India

    Bian, David W
    The aim of this research was to identify the effectiveness of cost-optimizing a photovoltaic-powered electrodialysis reversal (PV-EDR) system for village-scale applications in rural India based on current component costs and performance. Currently available village-scale off-grid desalination systems have high capital costs - $11,250 USD compared to $4,500 USD for equivalent grid-connected systems - rendering them prohibitively expensive for cost-constrained communities. Compared to current state-of- the-art PV-powered reverse osmosis desalination systems, electrodialysis has the potential to reduce capital cost due to the lower energy requirement of the ED process at brackish feed water salinities. The parametric relationships that govern the characteristics...

  8. Design, development, and field-testing of a cost-optimized village-scale, photovoltaic-powered, electrodialysis reversal water desalination system for rural India

    Bian, David W
    The aim of this research was to identify the effectiveness of cost-optimizing a photovoltaic-powered electrodialysis reversal (PV-EDR) system for village-scale applications in rural India based on current component costs and performance. Currently available village-scale off-grid desalination systems have high capital costs - $11,250 USD compared to $4,500 USD for equivalent grid-connected systems - rendering them prohibitively expensive for cost-constrained communities. Compared to current state-of- the-art PV-powered reverse osmosis desalination systems, electrodialysis has the potential to reduce capital cost due to the lower energy requirement of the ED process at brackish feed water salinities. The parametric relationships that govern the characteristics...

  9. Curved beam based model for piston-ring designs in internal combustion engines

    Bhouri, Mohamed Aziz
    Characterizing the piston ring behavior is inherently associated with the oil consumption, friction, wear and blow-by in internal combustion engines. This behavior varies along the ring's circumference and determining these variations is of utmost importance for developing ring-packs achieving desired performances in terms of sealing and conformability. This study based on straight beam model was already developed but does not consider the lubrication sub-models, the tip gap effects and the characterization of the ring free shape based on any final closed shape. In this work, three numerical curved beam based models were developed to study the performance of the piston...

  10. Curved beam based model for piston-ring designs in internal combustion engines

    Bhouri, Mohamed Aziz
    Characterizing the piston ring behavior is inherently associated with the oil consumption, friction, wear and blow-by in internal combustion engines. This behavior varies along the ring's circumference and determining these variations is of utmost importance for developing ring-packs achieving desired performances in terms of sealing and conformability. This study based on straight beam model was already developed but does not consider the lubrication sub-models, the tip gap effects and the characterization of the ring free shape based on any final closed shape. In this work, three numerical curved beam based models were developed to study the performance of the piston...

  11. Fabrication and qualification of arbitrarily patterned seamless tooling for continuous roll-to-roll microcontact printing

    Ascoli, Peter A
    Microcontact printing is form of soft lithography utilizing an elastomeric stamp with a molded relief pattern to print features on substrates through ink transfer at micron and nanometer scales. This is a low-cost technique when compared with other printing and patterning processes. Traditional microcontact printing using flat stamps and planar, rigid substrates, which limit production output, manufacturing scale, and capital efficiency. However, a precise, scalable, roll-to-roll process could lower production costs, increase output, and enable the creation new technologies. Specifically, flexible displays, photovoltaic systems and accessories, and other large area electronics could be fabricated using a continuous roll-to-roll microcontact printing...

  12. Fabrication and qualification of arbitrarily patterned seamless tooling for continuous roll-to-roll microcontact printing

    Ascoli, Peter A
    Microcontact printing is form of soft lithography utilizing an elastomeric stamp with a molded relief pattern to print features on substrates through ink transfer at micron and nanometer scales. This is a low-cost technique when compared with other printing and patterning processes. Traditional microcontact printing using flat stamps and planar, rigid substrates, which limit production output, manufacturing scale, and capital efficiency. However, a precise, scalable, roll-to-roll process could lower production costs, increase output, and enable the creation new technologies. Specifically, flexible displays, photovoltaic systems and accessories, and other large area electronics could be fabricated using a continuous roll-to-roll microcontact printing...

  13. Supernumerary robotic limbs for human augmentation in overhead assembly tasks

    Bright, Lawrence (Lawrence Zack)
    Manufacturing tasks are highly demanding of work, and there is an especially high prevalence of injury associated with overhead tasks which are taxing to the shoulder and upper body. To assist workers completing these tasks, and to increase overall productivity, safety and effectiveness, we introduce a novel design of Supernumerary Robotic Limb (SRL). This is a robotic arm worn on the shoulder of the technician/- worker which extends the human capability with implicit force control algorithms that allow for intuitive control and interface of the extra robot arm. Affectionately dubbed Aucto, the robotic arm can lift an object and hold...

  14. Supernumerary robotic limbs for human augmentation in overhead assembly tasks

    Bright, Lawrence (Lawrence Zack)
    Manufacturing tasks are highly demanding of work, and there is an especially high prevalence of injury associated with overhead tasks which are taxing to the shoulder and upper body. To assist workers completing these tasks, and to increase overall productivity, safety and effectiveness, we introduce a novel design of Supernumerary Robotic Limb (SRL). This is a robotic arm worn on the shoulder of the technician/- worker which extends the human capability with implicit force control algorithms that allow for intuitive control and interface of the extra robot arm. Affectionately dubbed Aucto, the robotic arm can lift an object and hold...

  15. Integrating design and optimization tools : a designer-centered study

    Burnell, Edward (Edward E.)
    Exploring design options for additively manufactured parts generally requires separate, sequentially applied software for design, analysis, and optimization. To evaluate the effect of integrating these capabilities within a single tool we conducted a controlled human subjects study. Three tools with different degrees of integration were created for two test cases of structural trusses, and it was found that increased integration improved quality, speed, and efficiency of the design process. After a quarter of their total time with the problems, 50% of designers with a fully integrated tool had a better design than 75% of other designers ever would. After that...

  16. Integrating design and optimization tools : a designer-centered study

    Burnell, Edward (Edward E.)
    Exploring design options for additively manufactured parts generally requires separate, sequentially applied software for design, analysis, and optimization. To evaluate the effect of integrating these capabilities within a single tool we conducted a controlled human subjects study. Three tools with different degrees of integration were created for two test cases of structural trusses, and it was found that increased integration improved quality, speed, and efficiency of the design process. After a quarter of their total time with the problems, 50% of designers with a fully integrated tool had a better design than 75% of other designers ever would. After that...

  17. The Makaa Project : co-design, performance testing, and techno-economics to improve a Ugandan charcoal cookstove

    Bustamante, Lauren E
    Like many developing nations in Africa, Uganda has a very high reliance on solid fuels such as firewood and charcoal. These solid fuels are used in conjunction with a variety of cooking methods, ranging from three stone fires to improved cookstoves. Appropriate Energy Saving Technologies (AEST) is a social business enterprise that manufactures and distributes the Makaa charcoal cookstove and a long-time partner of MIT's D-Lab. This work is a collaboration with AEST to improve the performance, usability, and manufacturability of the Makaa stove. A one-day co-design workshop was held at the AEST site in Soroti to engage users, fabricators,...

  18. The Makaa Project : co-design, performance testing, and techno-economics to improve a Ugandan charcoal cookstove

    Bustamante, Lauren E
    Like many developing nations in Africa, Uganda has a very high reliance on solid fuels such as firewood and charcoal. These solid fuels are used in conjunction with a variety of cooking methods, ranging from three stone fires to improved cookstoves. Appropriate Energy Saving Technologies (AEST) is a social business enterprise that manufactures and distributes the Makaa charcoal cookstove and a long-time partner of MIT's D-Lab. This work is a collaboration with AEST to improve the performance, usability, and manufacturability of the Makaa stove. A one-day co-design workshop was held at the AEST site in Soroti to engage users, fabricators,...

  19. Passive enhancement of air flow at pedestrian level in built environments

    Chew, Lup Wai
    A densely built environment has low wind speed at the pedestrian level due to flow obstruction induced by buildings. Urban street canyons, the outdoor spaces formed between buildings, often have much lower wind speed than the atmospheric wind above the roof level. In tropical regions, wind plays an important role to improve outdoor thermal comfort of urban inhabitants by increasing the convective heat transfer from body surfaces. This thesis explores four types of passive architectural interventions to boost pedestrian-level wind speed in urban street canyons, namely void decks (open ground level), the wind catcher, the reversed wind catcher, and step-up/...

  20. Passive enhancement of air flow at pedestrian level in built environments

    Chew, Lup Wai
    A densely built environment has low wind speed at the pedestrian level due to flow obstruction induced by buildings. Urban street canyons, the outdoor spaces formed between buildings, often have much lower wind speed than the atmospheric wind above the roof level. In tropical regions, wind plays an important role to improve outdoor thermal comfort of urban inhabitants by increasing the convective heat transfer from body surfaces. This thesis explores four types of passive architectural interventions to boost pedestrian-level wind speed in urban street canyons, namely void decks (open ground level), the wind catcher, the reversed wind catcher, and step-up/...

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