Rensselaer Polytechnic Institute

About: Rensselaer Polytechnic Institute is a education organization based out in Troy, New York, United States. It is known for research contribution in the topics: Terahertz radiation & Finite element method. The organization has 19024 authors who have published 39922 publications receiving 1414699 citations. The organization is also known as: RPI & Rensselaer Institute.

What stator current processing-based technique to use for induction motor rotor faults diagnosis?

Abstract: In recent years, marked improvement has been achieved in the design and manufacture of stator winding. However, motors driven by solid-state inverters undergo severe voltage stresses due to rapid switch-on and switch-off of semiconductor switches. Also, induction motors are required to operate in highly corrosive and dusty environments. Requirements such as these have spurred the development of vastly improved insulation material and treatment processes. But cage rotor design has undergone little change. As a result, rotor failures now account for a larger percentage of total induction motor failures. Broken cage bars and bearing deterioration are now the main cause of rotor failures. Moreover, with advances in digital technology over the last years, adequate data processing capability is now available on cost-effective hardware platforms, to monitor motors for a variety of abnormalities on a real time basis in addition to the normal motor protection functions. Such multifunction monitors are now starting to displace the multiplicity of electromechanical devices commonly applied for many years. For such reasons, this paper is devoted to a comparison of signal processing-based techniques for the detection of broken bars and bearing deterioration in induction motors. Features of these techniques which are relevant to fault detection are presented. These features are then analyzed and compared to deduce the most appropriate technique for induction motor rotor fault detection.

The Sample Analysis at Mars Investigation and Instrument Suite

Abstract: The Sample Analysis at Mars (SAM) investigation of the Mars Science Laboratory (MSL) addresses the chemical and isotopic composition of the atmosphere and volatiles extracted from solid samples. The SAM investigation is designed to contribute substantially to the mission goal of quantitatively assessing the habitability of Mars as an essential step in the search for past or present life on Mars. SAM is a 40 kg instrument suite located in the interior of MSL’s Curiosity rover. The SAM instruments are a quadrupole mass spectrometer, a tunable laser spectrometer, and a 6-column gas chromatograph all coupled through solid and gas processing systems to provide complementary information on the same samples. The SAM suite is able to measure a suite of light isotopes and to analyze volatiles directly from the atmosphere or thermally released from solid samples. In addition to measurements of simple inorganic compounds and noble gases SAM will conduct a sensitive search for organic compounds with either thermal or chemical extraction from sieved samples delivered by the sample processing system on the Curiosity rover’s robotic arm.

Wide bandgap compound semiconductors for superior high-voltage unipolar power devices

Abstract: This paper presents a critical evaluation of the performance capabilities of various wide bandgap semiconductors for high power and high frequency unipolar electronic devices. Seven different figures of merit have been analyzed. Theoretical calculations show that besides diamond and SiC, compounds like AlN, GaN, InN, and ZnO, and the intermetallics (Ga/sub x/In/sub 1-x/N, Al/sub x/In/sub 1-x/N, Al/sub x/Ga/sub 1-x/N, and (AlN)/sub x/(SiC)/sub 1-x/) offer several orders of magnitude improvement in the on-resistance and in the potential for successful operation at higher temperatures. >

Scientific Teams and Institution Collaborations: Evidence from U.S. Universities, 1981-1999

Abstract: This paper explores recent trends in the size of scientific teams and in institutional collaborations. The data derive from 2.4 million scientific papers written in 110 leading U.S. research universities over the period 1981-1999. We measure team size by the number of authors on a scientific paper. Using this measure we find that team size increases by 50 percent over the 19-year period. We supplement team size with measures of domestic and foreign institutional collaborations, which capture the geographic dispersion of team workers. The time series evidence suggests that the trend towards larger and more dispersed teams accelerates at the start of the 1990s. This acceleration suggests a sudden decline in the cost of collaboration, perhaps due to improvements in telecommunications. Using a panel of top university departments we find that private universities and departments whose scientists have earned prestigious awards participate in larger teams, as do departments that have larger amounts of federal funding. Placement of former graduate students is a key determinant of institutional collaborations, especially collaborations with firms and foreign scientific institutions. Finally, the evidence indicates that scientific influence increases with team size and institutional collaborations. Since increasing team size implies an increase in the division of labor, these results suggest that scientific productivity increases with the scientific division of labor.

Microfabrication technology: Organized assembly of carbon nanotubes

Abstract: Cunning refinements help to customize the architecture of nanotube structures. Nanoscale structures need to be arranged into well-defined configurations in order to build integrated systems. Here we use a chemical-vapour deposition method with gas-phase catalyst delivery to direct the assembly of carbon nanotubes in a variety of predetermined orientations onto silicon/silica substrates, building them into one-, two- and three-dimensional arrangements. The preference of nanotubes to grow selectively on and normal to silica surfaces forces them to inherit the lithographically machined template topography of their substrates, allowing the sites of nucleation and the direction of growth to be controlled.