Evaluation, design, and construction of the Wallace Astrophysical Observatory Camera for astronomical observations

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, June 2009."May 2008." Cataloged from PDF version of thesis.Includes bibliographical references (p. 53-54).The goal of this thesis is to upgrade the scientific capabilities of the 24" Cassegrain reflector telescope at the George R. Wallace, Jr. Astrophysical Observatory (Wallace Observatory), part of Massachusetts Institute of Technology (MIT). The upgrade consists of evaluating, designing and constructing the Wallace Astrophysical Observatory Camera (WAOcam), optimized for 24" telescope. A full 3D model of the 24" telescope and dome was created to find the size restrictions for WAOcam. An optical model was also developed to maximize the field of view of the camera detector. WAOcam was designed using SolidWorks (3D modeling Software), the parts files from the designing process were also used to machine the instrument. The manufacturing of the WAOcam involved using the following: Computer Numerical Control (CNC) lathe, CNC mill, drill press, and a Waterjet (cutting machine). The manufacturing process also required learning of Omax (software for the Waterjet) and MasterCam 9.1 (software for the CNC lathe and CNC mill). The resulting product is WAOcam, which consists of three modules: 1) vacuum dewar (houses a CCD detector), 2) shutter (controls when light hits the camera detector), and 3) filter wheel (modifies the light before hitting the detector). The remaining work left on the WAOcam is the installation of two additional modules: 1) a four port instrument rotator and 2) a field rotator. This upgrade will allow for occultation observations, strip scanning surveys, and Kuiper Belt Object (KBOs) astrometry to be obtained using the 24" telescope.by Folkers Eduardo Rojas.S.B

Heat extraction for the CSPonD thermal storage unit

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, February 2011."February 2011." Cataloged from PDF version of thesis.Includes bibliographical references (p. 78).Three coiled tube heat exchanger prototypes were designed to extract heat from containers holding 0.5 kg, 2.3 kg, and 10.5 kg of Sodium Nitrate-Potassium Nitrate salt. All of the prototypes were left with an open surface free to undergo radiation losses and surface convection. The first objective was to measure the power extraction over time for each prototype. Coiled tube heat exchangers were modeled as a tube with a constant wall temperature. Air is used as the working fluid, with a maximum Reynolds number of 2000 at a maximum flow rate of 10 standard liters per minute (SLPM) at air flow temperatures above 900°C. The accuracy of the power extraction model for the three prototypes in increasing order: 46 %, 35 %, and 43 % of the measured data. The duration of power extraction with an open top container for the first (P-1), second (P-l1), and third (P-II) prototype respectively are: 14 min, 29 min, 45 min producing an average power of 22 W, 23 W, and 22 W respectively. To compare across the prototypes, the data provided is for bath bulk temperatures starting at 330°C and ending at 275' C. Prototype three produced 25 W for 123 minutes for the same temperature change in the bulk temperature (330° to 275°C) with the lights off and a thermal lid, to reduce radiation and surface convection losses. The thermal lid improved the extraction duration by a factor of four. The second objective was to characterize the thermal loss rate (W) of the each prototype. The thermal loss rate model is accurate within 28.9 % (P-1), 28.7 % (P-11), and 24.7 % (P-III) of the measured values. There is evidence of convection cells in prototype two and three. A high temperature Particle Image Velocimetry (PIV) system has been proposed to measure the magnitude of the convection cells, and a proof of concept setup has been tested. Particles native to the molten salt are illuminated using a Class 3b laser (power <5mW). The laser beam is converted into a plane using a polypropylene conical centrifuge tube filled with water.by Folkers Eduardo Rojas.S.M

HAWK for rapidly controlling a free flowing oil well

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014."June 2014." Cataloged from PDF version of thesis.Includes bibliographical references (pages 189-195).To mitigate the impact of a Blowout Preventer (BOP) failure, this work proposes a method and machine that can create a gradual flow reduction to zero in an offshore well by introducing a mechanical plug inside the BOP. The backup safety tool, referred to as the Hampering Active Wellbore Kit (HAWK), is a machine that gradually introduces a continuous medium (e.g. wire) from a spool through the choke/kill lines of a failed BOP to gradually stem the flow through the BOP. The machine can couple to a standard choke/kill line on the BOP and can co-exist with the BOP or be deployed at the time of an accident. This work presents the design theory for wire feeding in order to form an entanglement, and the mechanism by which to accomplish the reliable feeding of the continuous structure. The efficacy of the entanglement is evaluated by comparing flow rates of a single experimental wellbore before and after the introduction of the mechanical plug.by Folkers Eduardo Rojas.Ph. D

Caribbean-Wide, Negative Emissions Solution to Sargassum spp. Low-Cost Collection Device and Sustainable Disposal Method

Sargassum spp. blooms exacerbated by climate change and agricultural runoff are inundating Caribbean beaches, emitting toxic fumes and greenhouse gases through decomposition. This hurts tourism, artisanal fishing, shore-based industry, human health, standards-of-living, coastal ecology, and the global climate. Barriers, collection machinery, and Sargassum valorization have been unable to provide sufficient, sustainable, or widespread relief. This article presents a total Sargassum management system that is effective, low-impact, and economically scalable across the Caribbean. Littoral Collection Modules (LCMs), attached to artisanal fishing boats, collect Sargassum in nets which are brought to a barge. When full, the barge is towed to the deep ocean where Sargassum is pumped to ~150–200 m depth, whereafter it continues sinking (Sargassum Ocean Sequestration of Carbon; “SOS Carbon”). Costing and negative emissions calculations for this system show cleanup costs &lt;$1/m3 and emissions reduction potential up to 1.356 → 3.029 tCO2e/dmt Sargassum. COVID-19 decimated Caribbean tourism, adding to the pressures of indebtedness and natural disasters facing the region. The “SOS Carbon strategy” could help the Caribbean “build back better” by establishing a negative emissions industry that builds resilience against Sargassum and flight shame (“flygskam”). Employing fishermen to operate LCMs achieves socioeconomic goals while increasing Sargassum cleanup and avoiding landfilling achieves sustainable development goals

Stellenwert von patientenberichteten Endpunkten (PRO) im HTA - Eine empirische Analyse anhand von zwei Beispielindikationen

A concentrating solar power system is presented which uses hillside mounted heliostats to direct sunlight into a volumetric absorption molten salt receiver with integral storage. The concentrated sunlight penetrates and is absorbed by molten salt in the receiver through a depth of 4–5 m, making the system insensitive to the passage of clouds. The receiver volume also acts as the thermal storage volume eliminating the need for secondary hot and cold salt storage tanks. A small aperture and refractory-lined domed roof reduce losses to the environment and reflect thermal radiation back into the pond. Hot salt is pumped from the top of the tank through a steam generator and then returned to the bottom of the tank. An insulated barrier plate is positioned within the tank to provide a physical and thermal barrier between the thermally stratified layers, maintaining hot and cold salt volumes required for continuous operation. As a result, high temperature thermal energy can be provided 24/7 or at any desired time. The amount of storage required depends on local needs and economic conditions. About 2500 m[superscript 3] of nitrate salt is needed to operate a 4 MW[subscript e] steam turbine 24/7 (7 h sunshine, 17 h storage), and with modest heliostat field oversizing to accumulate energy, the system could operate for an additional 24 h (1 cloudy day). Alternatively, this same storage volume can supply a 50 MWe turbine for 3.25 h without additional solar input. Cosine effect losses associated with hillside heliostats beaming light downwards to the receiver are offset by the elimination of a tower and separate hot and cold storage tanks and their associated pumping systems. Reduced system complexity also reduces variable costs. Using the NREL Solar Advisor program, the system is estimated to realize cost-competitive levelized production costs of electricity.Bill & Melinda Gates Foundation (Fellowship)Chesonis Family Foundation (Fellowship

Rapidly scalable mechanical ventilator for the COVID-19 pandemic

The SARS-CoV-2 pandemic is straining healthcare systems worldwide, and a global ventilator shortage is fueling the dire situation. As a response, the MIT E-Vent Team (S1) manufactured a scalable ventilator prototype for mass production and demonstrated basic clinical feasibility