Feasibility of the implementation of solar heat sources for bridge deck applications

Deicing salts have caused damage and early failure of the concrete cover and corrosion of reinforcing steel of concrete bridge decks. The use of wax to internally seal Portlant Cement concrete bridge decks and the use of monomers to polymerize concrete have been researched as methods to repair deteriorated decks and to prevent the penetration of salt into the conrete. Both methods require heating the concrete to a depth of two inches to temperatures of 160 to 190 degrees F. Eelctrical and propane heating systems are expensive to buy and operate. Solar equipment may be more simple and uses a source of energy that is both free and non-polluting. the installation of two cathodic protection systems as part of the Federal Highway Administration's Demonstration Project No. 34, "Cathodic Protection for Reinforced Concrete Bridge Decks". Two different types of cathodic protection systems were installed under this contract. The first system known as a "slotted" or non-overlay system consists of anodes which are installed in slots that have been sawed in the bridge deck. The second system is an overlay system in which the anodes are installed on top of the deck and then a 2 inch high density concrete overlay is piaced. Both systems were of the impressed current type using the local utility company for power. This is the second year evaluation of the project.N

Heating ventilating, and air conditioning : analysis and design/ McQuiston

xix, 742 hal.: ill.; 24 cm

Heating ventilating, and air conditioning : analysis and design/ McQuiston

xix, 742 hal.: ill.; 24 cm

Solid Dielectric Transmission Lines for Pulsed Power

This paper documents recent work developing solid dielectric transmission lines for sub-microsecond, 100 kV class compact pulsed power systems. Polymer-ceramic nanocomposite materials have demonstrated sub-microsecond discharge capability in parallel plate capacitors and transmission lines [1, 2]. With a dielectric constant of approximately 50, the propagation velocity is 2.5 cm/ns, necessitating lines of several meters length to achieve \u3e 100 ns pulse lengths. By folding the line in a fashion analogous to ceramic multilayer capacitors, the physical length of the line can be significantly shorter than the electrical length. We present the results of an experimental effort to develop a folded transmission line using a polymer-ceramic nanocomposite dielectric. The pulse length was somewhat shorter than expected based on a simple calculation using the geometry and the dielectric constant. Fully 3-D electromagnetic calculations were used to examine the role of the edges in curtailing the pulse length. Dielectric breakdown in this device occurred below the electric field threshold demonstrated in the prior work [1]. Improvements in the large scale fabrication of TiO2 beginning with nanoscale grains have opened the possibility for producing single layer high voltage devices. Given a dielectric constant approaching 140, transmission lines using nano-TiO2 can be considerably shorter than with other materials. Relatively thick, flat sheets of TiO2 have been fabricated for testing up to 50 kV. Several transmission lines, employing a serpentine electrode geometry, have been manufactured and tested. Testing up to several 10\u27s of kV has confirmed the operation of the lines according to the design. As expected, the triple point between the TiO2, electrode, and insulating medium has proven difficult to manage for high voltage operation. Several techniques to mitigate the effects of the triple point, including resistive grading at the edges of the electrodes, are discussed. Fully 3-D electromagnetic modeling is used to examine the effects of electrode geometry and composition on the performance of the lines

Material science experiments on the Atlas Facility

Three material properties experiments that are to be performed on the Atlas pulsed power facility are described; friction at sliding metal interfaces, spallation and damage in convergent geomety, and plastic flow at high strain and high strain rate. Construction of this facility has been completed and experiments in high energy density hydrodynamics and material dynamics will begin in 2001