Critical Speeds Of Turbomachinery: Computer Predictions Vs. Experimental Measurements.

LecturePg. 105-130As a result of a continuing demand for increased performance, modern turbomachines are sometimes designed to operate near a critical speed. Machines for petrochemical and natural gas service have been purchased and delivered which were later discovered to be operating so close to a critical speed as to cause difficulty in maintaining the rotor balance required to ensure acceptable vibration levels. A serious requirement for an accurate critical speed prediction capability is thus indicated. Field experience has shown that the accuracy of computer predicted critical speeds of contemporary turbomachines is sometimes open to question. Reports on research to experimentally verify existing computer programs for a priori critical speed prediction are almost nonexistent in the engineering literature. Comparisons of state-of-the-art computer predictions of critical speeds are described herein, with experimental measurements on shafts and rotors of varying complexity. The models investigated range from a precision uniform shaft in the laboratory to an eight-stage centrifugal compressor rotor. Modifications made to existing computer programs to improve the accuracy of predicted critical speeds are also discussed. Special care must be taken to properly define the rotor-mass elastic model, which depends on the features of the computer program employed. The accuracy of critical speed predictions is shown to depend on: 1) the accuracy of the free-free rotor vibration models, which depends on the accuracy of the rotor mass-elastic model, once the computer algorithm is optimized, 2) the accuracy of the bearing stiffness and damping coefficients, which are speed dependent in the case of fluid-film bearings, and 3) the accuracy of the dynamic properties of the foundation, which can be represented by a frequency-dependent impedance and which must be determined by experimental measurements. In the special case of tilt-pad bearings, existing data on the stiffness properties was found to be unsatisfactory. Measurements were made and the new results are reported herein. Measurements made on one of the laboratory models, a three-disk rotor on tilt-pad bearings, showed subsynchronous whirl, which is not explainable by contemporary instability theory unless the tilt-pad bearings have significant cross-coupling and less damping than the available literature predicts

The Grizzly, February 6, 2014

Reimert Party Suspension Sparks USGA Meeting About Safety Risks • Career Department Clarifies Post-Grad Placement Data • Representative Will Discuss Drexel\u27s Graduate Programs • Wismer Sanitation Revisited • Auntie Anne Shares Pretzel Wisdom with U-Innovate! • CIE Hits the Road for UC Graduates • Summer Mentors to Continue • Opinion: Ursinus Drug Policy Should Adhere to the Law; Multilingual Education Should be Considered • Blowout on Super Bowl Sunday • Krasna Chasing 1000, Succeeding in Classroom • Men\u27s Basketball Breaks Losing Streak; Wrestling and Women\u27s Swimming Remain Undefeatedhttps://digitalcommons.ursinus.edu/grizzlynews/1896/thumbnail.jp

The Grizzly, February 13, 2014

Annual Job, Internship and Networking Fair Brings Potential Employers to the Ursinus Campus • International Medical Corps Representative to Speak This Wednesday • History Department Holds Nazi Regime Lecture • ZBS Group to Perform in Valentine\u27s Day Improv Workshop • Recycle Mania Returns to UC • Students Bring Composting to Lower • Wismer Music Open to Input • TLI Reps to Visit Hong Kong • Opinion: Smartphones Make Communication a Chore; The Endgame of Piracy is Product Placement • Men\u27s Lacrosse Boasts Strong Senior Class • All-American Football Player Announces He is Gay • Winter Sports Regular Season Coming to Closehttps://digitalcommons.ursinus.edu/grizzlynews/1897/thumbnail.jp

The Grizzly, February 20, 2014

Student Senate Assembled After Reimert Party Ban • Ursinus to Hold First Musical Combining Three Departments • Professors Determine Class Cancellations • More Than 300 Students Attend Job Fair This Year • Professors Return to Campus Life • Heavy Snowfall no Match for Facilities; Ursinus Remains Open • Student Response Counts When Hiring Faculty • Opinion: Supply Chain is Our Biggest Food Risk; Michael Sam Shouldn\u27t Need a Press Conference • Record-Breaking Career for UC Swimmer • Large Freshman Class Will Help Baseball Bounce Back • Winter Sports End Regular Season on High Notehttps://digitalcommons.ursinus.edu/grizzlynews/1898/thumbnail.jp

Effects of IRF5 Lupus Risk Haplotype on Pathways Predicted to Influence B Cell Functions

Both genetic and environmental interactions affect systemic lupus erythematosus (SLE) development and pathogenesis. One known genetic factor associated with lupus is a haplotype of the interferon regulatory factor 5 (IRF5) gene. Analysis of global gene expression microarray data using gene set enrichment analysis identified multiple interferon- and inflammation-related gene sets significantly overrepresented in cells with the risk haplotype. Pathway analysis using expressed genes from the significant gene sets impacted by the IRF5 risk haplotype confirmed significant correlation with the interferon pathway, Toll-like receptor pathway, and the B-cell receptor pathway. SLE patients with the IRF5 risk haplotype have a heightened interferon signature, even in an unstimulated state (P = 0.011), while patients with the IRF5 protective haplotype have a B cell interferon signature similar to that of controls. These results identify multiple genes in functionally significant pathways which are affected by IRF5 genotype. They also establish the IRF5 risk haplotype as a key determinant of not only the interferon response, but also other B-cell pathways involved in SLE

Genome-wide association analysis of eosinophilic esophagitis provides insight into the tissue specificity of this allergic disease

Eosinophilic esophagitis (EoE) is a chronic inflammatory disorder associated with allergic hypersensitivity to food. We interrogated >1.5 million genetic variants in European EoE cases and subsequently in a multi-site cohort with local and out-of-study control subjects. In addition to replication of the 5q22 locus (meta-analysis p = 1.9×10−16), we identified association at 2p23 (encoding CAPN14, p = 2.5×10−10). CAPN14 was specifically expressed in the esophagus, dynamically upregulated as a function of disease activity and genetic haplotype and after exposure of epithelial cells to IL-13, and located in an epigenetic hotspot modified by IL-13. There was enriched esophageal expression for the genes neighboring the top 208 EoE sequence variants. Multiple allergic sensitization loci were associated with EoE susceptibility (4.8×10−2 < p < 5.1×10−11). We propose a model that elucidates the tissue specific nature of EoE that involves the interplay of allergic sensitization with an EoE-specific, IL-13–inducible esophageal response involving CAPN14

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in July 2014. It pursues three core programs: APOGEE-2,MaNGA, and eBOSS. In addition, eBOSS contains two major subprograms: TDSS and SPIDERS. This paper describes the first data release from SDSS-IV, Data Release 13 (DR13), which contains new data, reanalysis of existing data sets and, like all SDSS data releases, is inclusive of previously released data. DR13 makes publicly available 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA,the first data released from this survey. It includes new observations from eBOSS, completing SEQUELS. In addition to targeting galaxies and quasars, SEQUELS also targeted variability-selected objects from TDSS and X-ray selected objects from SPIDERS. DR13 includes new reductions ofthe SDSS-III BOSS data, improving the spectrophotometric calibration and redshift classification. DR13 releases new reductions of the APOGEE-1data from SDSS-III, with abundances of elements not previously included and improved stellar parameters for dwarf stars and cooler stars. For the SDSS imaging data, DR13 provides new, more robust and precise photometric calibrations. Several value-added catalogs are being released in tandem with DR13, in particular target catalogs relevant for eBOSS, TDSS, and SPIDERS, and an updated red-clump catalog for APOGEE.This paper describes the location and format of the data now publicly available, as well as providing references to the important technical papers that describe the targeting, observing, and data reduction. The SDSS website, http://www.sdss.org, provides links to the data, tutorials and examples of data access, and extensive documentation of the reduction and analysis procedures. DR13 is the first of a scheduled set that will contain new data and analyses from the planned ~6-year operations of SDSS-IV.PostprintPeer reviewe