Octave-tunable miniature RF resonators

The development and testing of a miniaturized, high-Q, broadly tunable resonator is described. An exemplary device, with a center frequency that is continuously tunable from 1.2 to 2.6 GHz, was tested in detail. Experimental results demonstrated a resonator Q of up to 380, and typical insertion loss of -1.9 dB for a 25 MHz 3-dB bandwidth. These resonators have been used to stabilize a broadly-tunable oscillator with phase noise of -132 dBc/Hz at 100-kHz offset, with a center frequency tunable from 1.2-2.6 GHz, and a tuning speed of 1 GHz/ms

An ROV operated undersea hydraulic hose repair coupling

A 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

A New Phenomenon: Sub-Tg, Solid-State, Plasticity-Induced Bonding in Polymers

Polymer self-adhesion due to the interdiffusion of macromolecules has been an active area of research for several decades [70, 43, 62, 42, 72, 73, 41]. Here, we report a new phenomenon of sub-Tg, solid-state, plasticity-induced bonding; where amorphous polymeric films were bonded together in a period of time on the order of a second in the solid-state at ambient temperatures nearly 60 K below their glass transition temperature (Tg) by subjecting them to active plastic deformation. Despite the glassy regime, the bulk plastic deformation triggered the requisite molecular mobility of the polymer chains, causing interpenetration across the interfaces held in contact. Quantitative levels of adhesion and the morphologies of the fractured interfaces validated the sub-Tg, plasticity-induced, molecular mobilization causing bonding. No-bonding outcomes (i) during the compression of films in a near hydrostatic setting (which inhibited plastic flow) and (ii) between an 'elastic' and a 'plastic' film further established the explicit role of plastic deformation in this newly reported sub-Tg solid-state bonding

A Two-Pressure Humidity Generator

A 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)

Sensor system design to determine position and orientation of articulated structures

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.Includes bibliographical references.by Alexander H. Slocum.Ph.D

Direct Absorption Volumetric Molten Salt Receiver With Integral Storage

A 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

Expectation Management in a Global Collaboration Project Using a Deterministic Design Approach

Expectation 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

Robust energy harvesting from walking vibrations by means of nonlinear cantilever beams

In the present work we examine how mechanical nonlinearity can be appropriately utilized to achieve strong robustness of performance in an energy harvesting setting. More specifically, for energy harvesting applications, a great challenge is the uncertain character of the excitation. The combination of this uncertainty with the narrow range of good performance for linear oscillators creates the need for more robust designs that adapt to a wider range of excitation signals. A typical application of this kind is energy harvesting from walking vibrations. Depending on the particular characteristics of the person that walks as well as on the pace of walking, the excitation signal obtains completely different forms. In the present work we study a nonlinear spring mechanism that is composed of a cantilever wrapping around a curved surface as it deflects. While for the free cantilever, the force acting on the free tip depends linearly on the tip displacement, the utilization of a contact surface with the appropriate distribution of curvature leads to essentially nonlinear dependence between the tip displacement and the acting force. The studied nonlinear mechanism has favorable mechanical properties such as low frictional losses, minimal moving parts, and a rugged design that can withstand excessive loads. Through numerical simulations we illustrate that by utilizing this essentially nonlinear element in a 2 degrees-of-freedom (DOF) system, we obtain strongly nonlinear energy transfers between the modes of the system. We illustrate that this nonlinear behavior is associated with strong robustness over three radically different excitation signals that correspond to different walking paces. To validate the strong robustness properties of the 2DOF nonlinear system, we perform a direct parameter optimization for 1DOF and 2DOF linear systems as well as for a class of 1DOF and 2DOF systems with nonlinear springs similar to that of the cubic spring that are physically realized by the cantilever–surface mechanism. The optimization results show that the 2DOF nonlinear system presents the best average performance when the excitation signals have three possible forms. Moreover, we observe that while for the linear systems the optimal performance is obtained for small values of the electromagnetic damping, for the 2DOF nonlinear system optimal performance is achieved for large values of damping. This feature is of particular importance for the system׳s robustness to parasitic damping.Massachusetts Institute of Technology. Naval Engineering Education Center. (Grant 3002883706)National Science Foundation (U.S.). Graduate Research Fellowship Program (Grant 1122374)MIT Energy Initiativ

Enhancing the Performance of the T-Peel Test for Thin and Flexible Adhered Laminates

Symmetrically bonded thin and flexible T-peel specimens, when tested on vertical travel machines, can be subject to significant gravitational loading; with the associated asymmetry and mixed-mode failure during peeling. This can cause erroneously high experimental peel forces to be recorded which leads to uncertainty in estimating interfacial fracture toughness and failure mode. To overcome these issues, a mechanical test fixture has been designed for use with vertical test machines, that supports the unpeeled portion of the test specimen and suppresses parasitic loads due to gravity from affecting the peel test. The mechanism, driven by the test machine cross-head, moves at one-half of the velocity of the cross-head such that the unpeeled portion always lies in the plane of the instantaneous center of motion. Several specimens such as bonded polymeric films, laminates, and commercial tapes were tested with and without the fixture, and the importance of the proposed T-peel procedure has been demonstrated

Extraction of Uranium from Seawater: Design and Testing of a Symbiotic System

Uranium present in low concentration in ocean water has the potential to greatly augment the current fuel reserve for nuclear power generation, but the challenge of extracting it economically remains. Two new designs of seawater uranium extraction systems are proposed in this paper—a stationary system and a continuous system—both of which utilize a braided polymer adsorbent. The stationary system simplifies the recovery procedure, and it is predicted to produce uranium at $326/kg. The continuous system is attached to an offshore wind turbine system to eliminate the need for additional mooring and increase the overall energy-gathering ability of the wind farm system. This system could maximize the adsorbent yield and achieve a production cost of$403/kg of uranium.MIT Energy InitiativeS. D. Bechtel, Jr. Foundatio