Free air breathing planar PEM fuel cell design for portable electronics

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (leaf 33).PEM fuel cell technology is an energy source that can provide several times more energy per unit volume then current lithium ion batteries. However, PEM fuel cells remain to be optimized in volume and mass to create a minimum size for integration into portable electronics. A planar fuel cell design utilizes the bare minimum in volume and mass over current stacked fuel cell designs. This was done by taking an innovative approach of assembling the fuel cell with just the bare minimum components, a proton exchange membrane, cathode electrode, anode electrode, and gas diffusion layer on both sides of the membrane to assume the role of GDL and current collector. This planar fuel cell design was able to produce a power density over 25mW/cm2. This is an order of magnitude lower then reported air breathing fuel cell values, however the route cause has been isolated to the ohmic losses of the planar fuel cell. Increasing the applied contact forces and creating low resistance electronically conductive grid lines, have shown to contribute to the reduction in ohmic resistance and will be the focus of future research. From this research, a planar fuel cell design has been shown to successful work and there are ways to improve its performance.by Ethan J. Crumlin.S.B

Aspects of Viking-Age Shipbuilding: In the Light of the Construction and Trials of the Skuldelev Ship-Replicas Saga Siglar and Roar Ege

Aspects of Viking-Age Shipbuilding: In the Light of the Construction and Trials of the Skuldelev Ship-Replicas Saga Siglar and Roar Eg

A model of teacher evaluation employing clinical supervision techniques : Newton, Massachusetts secondary public schools.

This study is an examination of the revised teacher evaluation procedures implemented by the Newton, Massachusetts public school department. The primary objective of the investigation was to determine how the participants, the teachers involved, viewed the pre-training, the common language features, the use of narrative evaluations, and the \u27cycle\u27 format proffered by Robert Goldhammer in his pioneering clinical supervision model designed at Harvard University in the mid 60\u27s. An analysis of the literature critiques and presents clinical supervision models from Green Bay, Wisconsin and Avondale, Michigan, as well as research that documents the evolution of clinical supervision, and its adaptation by educators such as Madeline Hunter. Higher means were recorded by respondents who participated in pre-training workshops, conducted over a three year period, than those who did not on all survey items. Teachers felt that they benefited from the revised evaluation procedure using clinical supervision techniques. They found narrative evaluative reports more helpful, especially the female teachers. They were clearer on common language terms shared with their supervisors and they found evaluation less a source of anxiety than those who did not participate in the pre-training

En kogge i Roskilde

Et af de mest betydningsfulde arkæologiske fund fra, de senere år er optagningen af de fem vikingeskibe i Peberrenden ved Skuldelev i Roskilde fjord. Hovedmanden bag dette skibsfund, museumsinspektør, cand. polyt. Ole Crumlin-Pedersen, fortæller om Roskildes betydning som søfartsby i vikingetid og tidlig middelalder og om forsvarsspærringerne i fjordens sejlled. Han beskriver i forbindelse hermed en indridset tegning af en kogge fra beg. af 1300- tallet i St. Jørgensbjerg kirke ved Roskilde

Methods for short-circuit identification and location in automobiles

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006."June 2006."Includes bibliographical references (leaf 133).As the number of electrical components in cars increases at a rapid rate, so too does the chance for electrical failure. A method for locating shorts to the chassis of a car is developed in this thesis. The developed technique is capable of detecting the approximate location of current being injected into the body of the car using several sensors placed strategically throughout the car. This technique can then be used in the manufacturing process and in the field where it can notify the operator of any short-circuit related problems in their car.by Alex Justin Crumlin.M.Eng

Fulton aus Marstal: ein dänischer Schoner in Vergangenheit und Gegenwart

Since the late 1960s, concerted efforts have been made in Denmark to preserve a small selection of characteristic Nordic wooden vessels of the sailing era for posterity. Of epochal significance within this context have been the endeavours of the National Museum in Copenhagen/Roskilde with regard to the FULTON, a three-masted schooner built in Marstal in 1915 and acquired by the museum in 1970. The history of the FULTON is divided into three sections: the period of the ship’s operation under sail as a cargo vessel on the North Atlantic from 1915 to 1923, then on the Baltic by sail and engine until 1969, and since 1970 as a sailing museum ship in Danish waters with a crew of Danish youth. The present article reports on the ship’s history and on the fates of several of the persons involved with her beginnings and early phase. The story of the FULTON serves as an example of how the circumstances of shipping in the past can by conveyed to the young generation of the present, and how the members of this generation can thus develop prospects for their own futures

Architectures for individual and stacked micro single chamber solid oxide fuel cells

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.Includes bibliographical references (p. 97-102).Solid oxide fuel cells (SOFCs) are electrochemical conversion devices that convert various fuel sources directly into electrical energy at temperatures ranging from 600°C to 1000°C. These high temperatures could potentially allow the direct use of various hydrocarbon fuel sources and hydrogen, without the need for expensive noble metal catalysis. Conventional SOFCs are designed in a two-chamber system, separating the fuel and oxidant flow to the anode and cathode, respectively. However, fuel cell manufacturing cost and robustness have proven to be the main challenges to rapid commercialization. A promising alternate method to achieve these requirements and to open up new architecture designs for the SOFC is the development of single-chamber solid oxide fuel cells (SC-SOFCs). SC-SOFCs avoid many of the manufacturing challenges associated with conventional SOFCs, and have shown optimal performance between 500°C and 800°C. This reduces the need for high temperature sealing and a complicated manifold structure; however it also reduces the partial pressure of the gases at the electrodes, which reduces the theoretical obtainable voltage.(cont.) Microfabrication techniques such as photolithography, sputtering, and photo-resist liftoff were used to create various micro SC-SOFC that are 25-400microns long and 15-40microns wide, utilizing platinum and gold for the electrodes and YSZ as the electrolyte. After successfully fabricating these micro SC-SOFCs, the fuel cells were tested in a microprobestation with a custom gas chamber enclosure, which was exposed to CH4:02:N2 at 20:20:100 ccm or 40:20:100 ccm. A switch in the OCV from a negative voltage to a positive voltage was observed around 600°C, possible indicating change in electrochemical reactions with temperature. An OCV of [approx.] 0.4V and peak power density of 27[mu]W/cm2 at 900°C in a 1:1 methane:oxygen ratio was achieved. A stack of 10 micro SC-SOFCs as fabricated showing a cumulative OCV of 3.3 V, of an average 0.33 V per cell at 600°C in a 2:1 methane:oxygen ratio. Ongoing research will involve characterizing micro SC-SOFCs to understand the fundamental reaction mechanisms, electrode materials, and architectures to obtain dense, high performing stacks of micro SC-SOFCs.by Ethan Jon Crumlin.S.M

Med Nordisk Maritimhistorisk Arbejdsgruppe hos Christian Madsen

Både forfatteren og Christian Nielsen var medlemmer af den »Nordiske maritimhistoriske arbejdsgruppe«, der var aktiv med feltarbejde i årene 1964-67. Artiklen giver indtryk af det udbytterige feltarbejde hos bådebygger Christian Madsen, Lynæs, i sommeren 1964