569 research outputs found
Platform for in-situ manufacturing of underground cable
No full textThesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2018Supervised by Alexander H. Slocum. Cataloged from PDF of thesis. Vitae.Includes bibliographical references (pages 83-86).As the demand for and viability of renewable energies has increased, connecting remote power generation stations to demand centers has become more important. High Voltage Direct Current (HVDC) transmission systems offer efficiency and cost effectiveness over long distances, allow for the linkage of incompatible AC grids, and can be immune to telluric currents and aggressive EMP attacks, which all make these systems particularly applicable to connecting to remote renewables. With the current state-of-the-art in HVDC, overhead lines (OHL) are several times cheaper than underground cables (UGC). However, OHLs have security risks and create substantial visual pollution, which has resulted in significant public opposition and lengthy delays in project permitting. Project developers have reluctantly agreed to replace portions of overhead line with underground cable as a concession to these stakeholders. One way to make UGCs more attractive to developers is to reduce cost by locating UGC systems along railroad right of ways. The increased mobility of heavy machines and materials on railroads and the state-of-the-art in railroad construction machinery provide both precedent and process advantages, which make the concept of augmenting railroads with underground cable systems an attractive one. The practice of installing and maintaining such systems could be less complex than traditional methods required by independent transmission corridors. The use of private railways may avoid conflicts with external stakeholders and eliminate the regulatory delays that have plagued many renewable energy transmission projects. Additionally, taking advantage of the increased accessibility of railroads by in-situ manufacturing high voltage, extruded cable in lengths far greater than what is currently able to be transported by road haulage, may reduce overall project costs by eliminating expensive and vulnerable cable splices. To accomplish this, here we present a method for continuously manufacturing and installing high voltage undergourd cable from a moving "Cable Train" using public-private railway systems. There are three primary challenges associated with such a mobile platform -- extrusion, curing, and degassing. Several promising countermeasures have been presented, which require varying levels of further development continuous extrusion, horizontal curing, and inline degassing. Herein, further discussions on standards, system topology, earthworks, practical limitations to cable production length, and cost estimation, can also be found. The technology and methods to accomplish this vision can be achieved by a pre-competitive technology consortium with member companies capable of completing and fully realizing the proof-of-concept designs proposed.by Luke A. Gray, Alexander H. Slocum and Qi Du.S.B.S.B. Massachusetts Institute of Technology, Department of Mechanical Engineerin
Symbiotic offshore energy harvesting and storage systems
No full textTaken separately, various offshore energy harvesting and storage machines can have a difficult time competing with land-based systems with regard to both initial capital cost and variable costs. However, collocating systems in a symbiotic way can lead to competitive advantages for offshore systems. This paper explores such combinations based on using the support structure for an offshore wind turbine as a basis for an energy storage system, a wave energy harvesting system, and a uranium-from-seawater mining system. Further considerations could also include aquaculture facilities as well as enhanced sport fisherman opportunities. Finally, far offshore systems are not only less likely to negatively impact birds, such as birds-of-prey, while experience with offshore oil platforms have been shown to act as undersea wildlife havens
Kinematic couplings: A review of design principles and applications
No full textFrom the humble three-legged milking stool to a SEMI standard wafer pod location to numerous sub-micron fixturing applications in instruments and machines, exactly constrained mechanisms provide precision, robustness, and certainty of location and design. Kinematic couplings exactly constrain six degrees of freedom between two parts and hence closed-form equations can be written to describe the structural performance of the coupling. Hertz contact theory can also be used to design the contact interface so very high stiffness and load capacity can also be achieved. Potential applications such as mechanical/electrical couplings for batteries could enable electric vehicles to rapidly exchange battery packs
An ROV operated undersea hydraulic hose repair coupling
No full textA hydraulic hose repair system is presented that was developed for use at the Deepwater Horizon accident site. The system can be deployed with a single ROV with two controllable arms. One arm holds the device and the other arm pushes a severed hose into the device. Hydraulic pressure is applied from the ROV to the device and a hydraulic coupling within the device is crimped into one end of the hose. The second hose end to be spliced to the first is pushed into the other side of the device and the second half of the coupling is crimped onto the second hose end. The device itself is left in place as part of the splice. The design, on-shore testing, and fabrication of multiple devices ready to deploy at the accident site took on the order of a week to complete. They stand ready to be deployed in the case of another deep-water accident. Keywords: Deepwater Horizon; Hydraulic; Hose; Repair; Couplin
Preliminary evaluation of robotic needle distal tip repositioning
No full textAdvances in medical imaging now provide detailed images of solid tumors inside the body and miniaturized energy delivery systems enable tumor destruction through local heating powered by a thin electrode. We have developed a robot for accurately repositioning the distal tip of a medical instrument such an ablation probe to adjacent points within tissue. The position accuracy in ballistics gelatin was evaluated in a 2D experimental setup with a digital SLR camera that was fixed to a rig that also contained the gelatin. The robot was mounted to the rig in such a way that the stylet was deployed in a plane parallel the camera's lens. A grid paper attached to the back of the box containing the gelatin provided a stationary reference point for each of the pictures taken and also served as a coordinate system for making measurements. The measurement repeatability error was found by taking a stylet tip position measurement five times for two different pictures and found to be 0.26 mm. For a stylet with a radius of curvature of 31.5 mm and a diameter of 0.838 mm, the targeting accuracy was found to be 2.5 ± 1.4 mm at points that were approximately 38 mm lateral from the cannula axis
Virtual cutter path display for dental milling machine
No full textThis paper presents the prototype of a mixed reality system using the computer controlled dental milling machine, which is called MRD Mill. First, overview of the core dental milling machine developed in this study is presented, showing its kinematics and mechanisms to achieve the objective of the dental treatment. Then the paper covers its basic functions, including joystick-based control, NC code-based control, manipulation recording, and replay operation for the manual manipulation. MRD Mill system was installed with a mixed reality technology using the dental milling machine as the core unit. MRD Mill system is designed to support the operation of the dental mill using the mixed reality technology. This paper shows superimpose of trajectory of cutting tool path and virtual objects over the physical model. Then discussion and future direction will be followed.Japan. Ministry of Education, Culture, Sports, Science and Technology (MEXT)Japan Society for the Promotion of Science (Grants-in-Aid for Scientific Research in 2006-2008 (Scientific Research (B) 18300170)
Design and evaluation of an abrasive saw kickback machine
No full textThesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2020Supervised by Alexander H. Slocum. Cataloged from the PDF version of thesis.Includes bibliographical references (page 65).Injuries from power saw kickback are often fatal. However, only woodcutting saws have regulations and assessment methodologies for kickback. These regulations do not apply to metal and masonry saws, as the cutting mechanism and dominant kick-back mode are different from those of woodcutting saws. In this work, the kickback of abrasive saws is investigated by combining theoretical and experimental tools. A theoretical model developed based on frictional engagement during a pinch-based kickback event is shown to predict the resultant kickback energy for various saws in good agreement with experimental measurements. These measurements were obtained using a specialized machine that was designed to generate pinch-based kickback and to measure the resultant kickback energy for both chainsaws and cutoff saws. While the model can predict the resultant kickback energy for a saw given known cutting conditions (i.e. cutting angle and pinch force), it does not predict the maximum possible kickback energy given any cutting angle of a saw because it does not account for the change in speed of the cutting blade. Upon validation of the physics model, two commonly used representative saws, a Stihl TS420 and an ICS 695XL, were tested using this kickback machine to evaluate their comparative kickback risk. This work demonstrates that pinch-based kickback can be a major safety risk for abrasive saw operators, and it provides a machine and analytical framework for evaluating this risk.by Steven Burcat.S.M.S.M. Massachusetts Institute of Technology, Department of Mechanical Engineerin
Direct Absorption Volumetric Molten Salt Receiver With Integral Storage
No full textA new design is presented for a concentrating solar power central receiver system with integrated thermal storage. Concentrated sunlight penetrates and is absorbed within a passive molten salt pool, also acting as a single-tank assisted thermocline storage system. The receiver has a relatively small aperture, open to the environment without requiring a transparent window to isolate the system, exhibiting low losses while achieving high temperatures needed for efficient power generation. The use of an insulated divider plate provides a physical and thermal barrier to separate the hot and cold salt layers within the receiver. The position of the divider plate is controlled throughout the day to enhance the natural thermocline which forms within the salt. As a result, continuous, high temperature heat extraction is possible even as the average temperature of the salt is declining. Experimental results are presented for an optically heated 5 L capacity sodium-potassium nitrate salt volumetric receiver equipped with a movable divider plate. Topics: Absorption, StorageBill & Melinda Gates Foundation (Graduate Student Fellowship)Chesonis Family Foundation (Graduate Student Fellowship
A Two-Pressure Humidity Generator
No full textA device for precisely humidifying a process gas is presented, with particular application to document preservation. The machine is designed to minimize the risk of damage from overpressure by incorporating multiple safety mechanisms and a simple user interface. The design theory is presented, discussed, and verified. This device is capable of generating humidified gases with relative humidities between 7 and 96 to high accuracy. At conditions suitable for document preservation, the machine is accurate to within 3.5 %, generating a relative humidity of (40 1.4)
Expectation Management in a Global Collaboration Project Using a Deterministic Design Approach
No full textExpectation management in product engineering design aims at setting achievable goals for both customers and designers, while leaving room for creativity and passion. This is especially challenging in the global workplace. Using an example of a design project, the Dental Headrest project (DHR), this paper reviews how expectations were managed in a successful, collaborative project between the University of Tokushima (UT) and Massachusetts Institute of Technology (MIT). The goal of the project was to design an innovative mechanism for the positioning a dental chair headrest so satisfy both the needs of a patient for comfort and a clinician for flexibility and access. The design team was formed with six students from the MIT MechE’s Precision Machine Design class, while the challenge proposed by a UT team of dentists and design engineers. The team followed a deterministic design procedure inducing understating the challenge and reviewing prior art, strategy and concept generation, detailed module design and fabrication and testing, culminating in presentation and documentation. Through the process was coordinated by online communication and collaborative working spaces which ensured real-time information transfer between the continents. The conclusion was a face-to-face meeting between the two institutions. This DHR project resulted in an innovative design of headrest adjusting mechanism that was implemented in a prototype. Moreover, the students, faculty and clinicians benefitted from the experience of innovative design collaboration in a multidisciplinary, global team.CIMIT: Center for Integration of Medicine and Innovative TechnologyJ. Morita Corporatio
- …
