Evaluation of the durability of hydrophobic treatments on concrete architectural heritage

peer reviewedThe protection of historical concrete structures is a challenge for the coming years. Hydrophobic treatment may reduce the deterioration process while providing protection against water penetration. Existing commercial products —mainly silane or siloxane in either water or solvent based formulations– were submitted to different ageing processes including UV radiation, dry-wet cycles, thermal shocks, freeze-thaw cycles, carbonation and their effectiveness has been evaluated on the basis of contact angle, vapour and chloride permeability and, capillarity water absorption. The results obtained clearly show that hydrophobic treatments display a good behaviour under the main ageing conditions.Monitoring dynamic network for existing structures of concrete Cultural Patrimon

Illinois Technograph v. 078, iss. 6 Mar. 1963

published or submitted for publicatio

Evidence of Counter-Streaming Ions near the Inner Pole of the HERMeS Hall Thruster

NASA is continuing the development of a 12.5-kW Hall thruster system to support a phased exploration concept to expand human presence to cis-lunar space and eventually to Mars. The development team is transitioning knowledge gained from the testing of the government-built Technology Development Unit (TDU) to the contractor-built Engineering Test Unit (ETU). A new laser-induced fluorescence diagnostic was developed to obtain data for validating the Hall thruster models and for comparing the behavior of the ETU and TDU. Analysis of TDU LIF data obtained during initial deployment of the diagnostics revealed evidence of two streams of ions moving in opposite directions near the inner front pole. These two streams of ions were found to intersect the downstream surface of the front pole at large oblique angles. This data points to a possible explanation for why the erosion rate of polished pole covers were observed to decrease over the course of several hundred hours of thruster operation

Special Libraries, September 1931

Volume 22, Issue 7https://scholarworks.sjsu.edu/sla_sl_1931/1006/thumbnail.jp

On-line Junction Temperature Estimation of SiC Power MOSFETs through On-state Voltage Mapping

This paper deals with real-time estimation of the junction temperature of SiC power MOSFETs. The junction temperature of one device of a 4-switch module is real-time estimated by measuring its current and on-state voltage VON at each switching period and entering the temperature look-up table of the device. The temperature model is preliminarily obtained in a dedicated commissioning session, where the VON is measured at different temperature and current conditions. The results show the feasibility of on-line temperature monitoring and even active limitation of the junction temperature of the tested SiC power MOSFET modules, accurately and with an instantaneous dynamic response. Different modules with die from different manufacturers were tested in a H-bridge demonstrator power converter, emulating the operating conditions of real converters such as voltage source DC/AC or DC/DC conversion structures. The commissioning procedure is meant to be performed directly on the final application for each converter. The proposed temperature estimation technique is validated against a thermal camera and compared to direct measurement of the die temperature with a thermistor, showing high accuracy and high feasibility

A review of air-fuel mixing and alternative methods in scramjets and scramjet-like engines.

This paper reviews work on two aspects of scramjet and similar ducted hypersonic propulsion. The first of these is air-fuel mixing techniques - the problem of mixing is considered the most intractable in scramjet design. The second aspect is the use of innovative techniques to supplement mixing or provide an alternative to combustion altogether. The paper outlines the mixing problem and reviews both classic treatments and newer, more innovative, work. In the light of this it also outlines conclusions and points out gaps in current knowledge and areas where more research is needed

Aeronautical Engineering: A continuing bibliography with indexes, supplement 113, September 1979

This bibliography lists 436 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1979

Kenyon College Bulletin No. 96 - The College Catalogue 1925-1926

https://digital.kenyon.edu/coursecatalogs/1110/thumbnail.jp