Critical speeds and forced response solutions for active magnetic bearing turbomachinery, part 2

The need for better performance of turbomachinery with active magnetic bearings has necessitated a study of such systems for accurate prediction of their vibrational characteristics. A modification of existing transfer matrix methods for rotor analysis is presented to predict the response of rotor systems with active magnetic bearings. The position of the magnetic bearing sensors is taken into account and the effect of changing sensor position on the vibrational characteristics of the rotor system is studied. The modified algorithm is validated using a simpler Jeffcott model described previously. The effect of changing from a rotating unbalance excitation to a constant excitation in a single plane is also studied. A typical eight stage centrifugal compressor rotor is analyzed using the modified transfer matrix code. The results for a two mass Jeffcott model were presented previously. The results obtained by running this model with the transfer matrix method were compared with the results of the Jeffcott analysis for the purposes of verification. Also included are plots of amplitude versus frequency for the eight stage centrifugal compressor rotor. These plots demonstrate the significant influence that sensor location has on the amplitude and critical frequencies of the rotor system

Hazardous Waste Reduction: Hexamethyldisiloxane

Waste Reduction: (1) Engineering problem - The manufacturing of a Silicone intermediate creates a flammable waste stream that must be disposed of at cost to QSI (0.48$/lb.). This stream contains two phases, which are mainly hexamethydisiloxane (HMDS) and aqueous ammonium hydroxide in roughly 50/50 ratio by volume. The HMDS phase (upper) is flammable and is thus hazardous. The clean aqueous phase (lower) can be discarded via the sewer at no cost if the flash point is above hazardous classification (60 °C). (2) Project deliverables - The Engineering solution must reduce the yearly volume of waste to under 13 tons/year and separate the mixture into two phases cleanly. Design and prototype a separation tank system that will allow the operator to safely decant the HMDS and dispose of the non-hazardous phase safely into the sewer. (3) Constraints - The system must prevent the operator from draining the flammable waste into the sewer before passing hazardous waste criteria while remaining intrinsically safe. The cost of the system must have a payback period of less than 5 years. (4) Approach - Develop analytical method to determine concentration and test initial flash point. Test salting concentrations then determine HMDS concentration change, add activated carbon in differing concentrations to determine absorption coefficient. (5) Results – 30 minute timed rough separation decanting top layer, adding 30$10,500/year.https://scholarscompass.vcu.edu/capstone/1082/thumbnail.jp

The ion velocity distribution function in a current-free double layer

A portable, low-power, diode laser-based laser-induced fluorescence(LIF)diagnostic incorporating a heated iodine cell for absolute wavelength reference was installed on the Chi-Kung helicon source [K. K. Chi, T. E. Sheridan, and R. W. Boswell, Plasma Sources Sci. Technol.8, 421 (1999)] to measure the ion velocity distribution function of argon ions as they transited a current-free double layer (DL) created where the solenoidal magnetic field diverges at the junction of the plasma source and the diffusion chamber. Based on LIFmeasurements of the transiting ion beam energy, the strength of the potential drop across the DL increases with decreasing neutral pressure and increasing magnetic field strength in the source. The location of the double layer also moves further downstream of the helicon source with increasing pressure. LIFmeasurements of the ion beam energy were found to be in good agreement with measurements obtained with a retarding field energy analyzer and also with numerical predictions.This work was supported by NSF Grant PHY-0315356, and the NSF EAPSI program in cooperation with Australian Academy of Science. A.M.K. was also supported by the DOE Fusion Energy Science Fellowship program

The CuSPED Mission: CubeSat for GNSS Sounding of the Ionosphere-Plasmasphere Electron Density

The CubeSat for GNSS Sounding of Ionosphere-Plasmasphere Electron Density (CuSPED) is a 3U CubeSat mission concept that has been developed in response to the NASA Heliophysics program's decadal science goal of the determining of the dynamics and coupling of the Earth's magnetosphere, ionosphere, and atmosphere and their response to solar and terrestrial inputs. The mission was formulated through a collaboration between West Virginia University, Georgia Tech, NASA GSFC and NASA JPL, and features a 3U CubeSat that hosts both a miniaturized space capable Global Navigation Satellite System (GNSS) receiver for topside atmospheric sounding, along with a Thermal Electron Capped Hemispherical Spectrometer (TECHS) for the purpose of in situ electron precipitation measurements. These two complimentary measurement techniques will provide data for the purpose of constraining ionosphere-magnetosphere coupling models and will also enable studies of the local plasma environment and spacecraft charging; a phenomenon which is known to lead to significant errors in the measurement of low-energy, charged species from instruments aboard spacecraft traversing the ionosphere. This paper will provide an overview of the concept including its science motivation and implementation

Solar Energy Industries Association v. Federal Energy Regulatory Commission

In Solar Energy Industries Association v. Federal Energy Regulatory Commission (“Solar Energy”), the court grappled with a complex web of regulatory and environmental considerations. The overall dispute was the promulgation and implementation of Order 872, a directive issued by the Federal Energy Regulatory Commission (“FERC” or “Commission”), and its alignment with the Public Utility Regulatory Policies Act of 1978 (“PURPA”) and the Administrative Procedure Act (“APA”). The dispute in Solar Energy is about FERC’s interpretation and application of PURPA in managing qualifying facilities (“QFs”). The crux of the contention was whether FERC’s 2020 rule revisions set forth in Order 872 were proper and whether FERC had sidestepped environmental safeguards stipulated by the National Environmental Policy Act (“NEPA”) by neglecting to prepare an environmental assessment or environmental impact statement. The case holds significant importance due to its potential environmental impact. If, as FERC predicts, there is an increase of small power production facilities, there would be an increase in renewable energy. In turn, leading to a substantial decrease in our dependence on fossil fuels, which would have the dual benefit of reducing greenhouse gas emissions and improving air quality. Furthermore, the shift towards renewable energy could stimulate economic growth by creating new jobs in the renewable energy sector. However, if as petitioners assert, the rule disincentivizes QF status or disqualifies more facilities than the prior rule, it could potentially lead to a decrease in renewable energy generation and an increase in greenhouse gas emissions, which would have negative environmental impacts. In essence, this ruling could have far-reaching impacts, shaping the future of renewable energy in the United States

Young athletes\u27 perceptions of playing through pain

Throughout the early career of an athlete, they are introduced and socialized into the sport ethic culture of risk of playing through pain. The purpose of this paper was to examine factors thought to influence young athletes’ conformity to the sport ethic by playing through pain. These factors included: athletic identity, fear of failure, and perceived pressure from important others to play through pain (Jessiman-Perreault & Godley, 2016; Nixon, 1994). The researcher contacted sport club organizations, recreational clubs, and school principals to seek cooperation. Participants included 140 male and female athletes aged 11-18 years old. Participants completed the Risk of Pain and Injury Questionnaire, Athletic Identity Measurement Scale, and the Performance Failure Appraisal Inventory. An athlete’s approval of withstanding the risks of pain and injury in sport was weakly, positively related to perceived pressure from significant others to play through pain and athletic identity. Athletes with high athletic identity expressed greater approval of withstanding the risks of pain and injury in sport. No difference was found between age groups on perceived pressure to play through pain from significant others. Perceived pressure from significant others to play through pain emerged as the strongest predictor for an athlete’s approval of withstanding the risks of pain and injury in sport. Future research should examine the difference between team and individual sports and their relationship to athletic identity, fear of failure, and perceived pressure from significant others to play through pain