Involuntary Volunteers: Public schools are starting to require students to serve their communities. Is that too much to ask?

As a student last year at Baltimore\u27s Dunbar High, Christina Mullins knew she wouldn\u27t be able to graduate unless she put in the 75 hours of community service required of all students by the state of Maryland

Lateral Rotordynamics of Petrochemical Equipment - Review, Examples and Problems

Short Cours

Shop Rotordynamic Testing - Options, Objectives, Benefits and Practices

TutorialUnderstanding the lateral rotordynamic behavior is critical in determining the reliability/operability of rotating equipment. Whether examining a centrifugal pump or compressor, steam or gas turbine, motor or generator, rotating machinery share the same need to accurately predict and measure dynamic behavior. Industrial specifications determining fit for purpose rely on the accuracy of rotordynamic predictions where direct measurement is impractical or otherwise impossible in an industrial setting. Testing to confirm rotordynamic prediction and behavior provides both the purchaser and vendor the confidence that the design will meet project expectations. Rotordynamic shop testing has several options available to the project during acceptance tests at the vendor’s shop. These options include mechanical run, string and full load/Type 1 testing as well as verification testing to validate unbalance response and stability predictions. Such testing has numerous advantages; the most important being the avoidance of production disruptions involved with testing at the job site. Each test option has associated costs as well as limitations as to what lateral vibration characteristics are revealed. Understanding these factors is vital to efficiently mitigate the risks associated with the purchased equipment. Applying best practices and an understanding of the industrial (API) test requirements are needed to derive the maximum benefit of each test option. The best practices not only involve the test procedure but also the associated analytical methods used to post process the measurement information. Whether performing a simple mechanical run test or more complex stability verification during ASME Type I testing, ensuring that a logical, repeatable and proven methodology is followed produces reliable evidence to confirm the rotordynamic model and lateral vibration performance. The rationale behind the API test requirements provides an understanding of why that test is being performed and its correct application to the dynamic behavior. Test options can be separated into two categories; tests that reveal portions of the dynamic behavior of the equipment to specific operating conditions and those used to verify the analytical predictions of that behavior. API mechanical, string and Type I (or full load) tests reveal the rotordynamic behavior of the equipment to a given set of conditions. These are used specifically to determine acceptability of the design. Unbalance and stability verification testing is used to confirm (or provide confidence in) the rotordynamic model. Confidence in the model permits extrapolation of the design (vendor) and operation (purchaser) beyond the machine’s asbuilt and specific shop test conditions

Predicting, Understanding and Avoiding the Ekofisk Rotor Instability Forty Years Later

LectureThis famous machine is re-examined to assess how well (or not) current design and analytical methods have evolved to avoid shaft whip instability. In addition to reviewing the compressors history and design evolution, the rotordynamic performance of a newly configured machine, based on todays technology, is compared against the original design

Economics as a Source of National Power

War by Other Means: Geoeconomics and Statecraft, by Robert D. Blackwill and Jennifer Harri

The Arctic viewed from Florence, Italy

We had an opportunity in 2021 to explore the world’s first museum of anthropology, which was founded in 1869 by Paolo Mantegazza (1831–1910), in Florence, in the context of many centuries of previous ethnographic and philosophical work that converged there. That same year Mantegazza also established the world’s first university professorship of anthropology. His museum, now lodged in the wonderfully named Palazzo Nonfinito, in the center of Florence, appears at first glance to be a relic of a now distant past, marooned in the 21st century—but it is not. The story of how this happened illuminates much about the history of anthropology. Over centuries, the disparate collections that the Medici had gathered in their home, the Palazzo di Medici, were eventually assembled in a chamber in the Palazzo Vecchio, the great medieval fortress in the city center, which is still the seat of government of the city-state. In 1563 Duke Cosimo I de Medici, newly proclaimed to royalty (by himself) commissioned the artist, art historian and architect Giorgio Vasari (1511–1574) to create a study chamber or ‘cabinet of curiosities. The Guardaroba became the first public site for display of the vast Medici collections. Duke Cosimo referred to “the cosmography in the Guardaroba”, reinforced by a set of beautiful painted maps hung on the doors of dozens of cabinets and rooms around the Guardaroba. Behind each door was collections of diverse treasures from the area mapped

Lateral Rotordynamics of Petrochemical Equipment - Review, Examples and Problems

Short Cours

Predicting, Understanding and Avoiding the Ekofisk Rotor Instability Forty Years Later

LectureThis famous machine is re-examined to assess how well (or not) current design and analytical methods have evolved to avoid shaft whip instability. In addition to reviewing the compressors history and design evolution, the rotordynamic performance of a newly configured machine, based on todays technology, is compared against the original design

Standby Electrical Power on Farms

This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu