The effect of stiffener parameters on the farfield sound radiation from composite beams: Experiment and theory

The effects of spatial and material variations on farfield sound radiation from carbon/epoxy composite beams were investigated. Specifically, the geometry of a single stiffener of carbon/epoxy embedded in a beam, periodically spaced stiffeners along the length of a beam, and single stiffeners of different materials embedded in beams were all investigated. Because of a lack of methods to sufficiently model the details of spatially varying material properties, experimental data were used to identify important parameters that needed to be included in a model. Vibration testing was performed for three frequency ranges: 500 Hz to 1500 Hz, 1500 Hz to 2500 Hz, and 2500 Hz to 3500 Hz. The geometry of a single stiffener of carbon/epoxy affected the region of the stiffener that radiated sound. Periodically spaced stiffeners tended to have a global stiffening effect at lower frequencies and to act like individual stiffeners for frequencies where the wavelength is shorter than the stiffener. A stiffener of viscoelastic material reduced the sound power radiated from the region of the stiffener, and stiffeners of other materials radiated sound from the ends of the stiffener. Vibration experiments were performed on fiber-reinforced composite beams to verify a cubic spline based solution of a simple Euler-Bernoulli beam model. The model seemed to accurately predict the shape and location of farfield sound radiation from stiffeners. However, limitations on the available boundary conditions prevented accurate prediction of the magnitude of sound radiation. The model was then used to predict sound radiation from beams with varying stiffener bond lengths and these results were experimentally verified. In general a longer stiffener bond length causes less sound radiation. However, there seems to be a critical length at which the sound radiation reaches a maximum

Material-based figure of merit for caloric materials

The efficient use of reversible thermal effects in magnetocaloric, electrocaloric, and elastocaloric materials is a promising avenue that can lead to a substantially increased efficiency of refrigeration and heat pumping devices, most importantly, those used in household and commercial cooling applications near ambient temperature. A proliferation in caloric material research has resulted in a wide array of materials where only the isothermal change in entropy in response to a handful of different field strengths over a limited range of temperatures has been evaluated and reported. Given the abundance of such data, there is a clear need for a simple and reliable figure of merit enabling fast screening and down-selection to justify further detailed characterization of those material systems that hold the greatest promise. Based on the analysis of several well-known materials that exhibit vastly different magnetocaloric effects, the Temperature averaged Entropy Change is introduced as a suitable early indicator of the material\u27s utility for magnetocaloric cooling applications, and its adoption by the caloric community is recommended

Compact and efficient elastocaloric heat pumps—Is there a path forward?

Elastocaloric cooling holds promise for energy-efficient heat pumping near room temperature with low environmental impact. Its adoption is, however, impeded by disproportionally large sizes of actuators compared with the active material volume. Taking magnetocaloric cooling as the baseline, the value of no more than 10:1 actuator volume to active material volume should lead to both size- and cost-effective solutions that may potentially be competitive with vapor-compression devices. With the goal to establish performance metrics that can lead to informed actuator selection for specific regenerator requirements, we analyze a wide range of elastocaloric materials and actuator technologies to find the best matches. We find that actuation with magnetic shape memory alloys meets all requirements; however, this technology is currently in early developmental stages and such actuators are not widely commercially available. Another promising and easily accessible option is standard rotary electric motors in combination with rotary-to-linear transduction mechanisms. A theoretical analysis of two case studies of elastocaloric systems using rotary electric motors with a Scotch yoke mechanism demonstrates the usefulness of our approach. Actuator requirements are based on two different regenerator configurations: one starting from zero strain without any mechanical energy recovery and another with 2% pre-strain and mechanical energy recovery to reduce the power and torque required from the motor. Our results indicate that the 10:1 target actuator to active material volume ratio can be met and feasibly lowered further, demonstrating that the proposed method for selecting actuators makes compact and efficient elastocaloric systems possible

The affordances and limitations of collaborative research in the TESOL classroom

The diversity of learning needs within the TESOL field creates inherent tensions between the need for targeted professional learning for TESOL teachers, the more generalist nature of tertiary TESOL courses, and the varied research interests of teacher educators. This article describes a collaborative research project between university-based teacher educators and TESOL teachers working in an adult education centre. With a range of aims amongst the research participants, this article reports on the ‘fluid’ and ‘messy’ process of collaborative research (Burns & Edwards, 2014, p. 67) as we investigate the use of identity texts (Cummins & Early, 2011) as a mediating tool for professional learning. In acknowledging the practice of teaching as highly situated, the data presented focuses on the individual experience of each teacher, voiced through an action research frame, before we discuss the achievements and challenges which emerged through this collaborative research process. In the findings, we argue for the importance of championing the case for the messy processes of collaborative research within the broader research academy

Velvet Brass

Capen Auditorium Edwards Hall Monday Evening March 31, 1997 8:00p.m

CaloriSMART: Small-scale test-stand for rapid evaluation of active magnetic regenerator performance

We report operation of a device designed specifically for rapid experimental evaluation of performance of magnetocaloric materials in different magnetic fields using a compact active magnetic regenerator bed with a total volume of approximately 5 mL. Other features of the system include digital control of the rotating-permanent-magnet field source and custom dual-opposed syringe pump that enable precise tuning and coupling of the flow profile and the magnetic field profile. Performance of the device is demonstrated for flow volumes between 1 and 4 mL (utilization from 0.48 to 1.9), maximum magnetic fields of 1.13 and 1.45 T, and applied cooling powers from 0 to 20 W at frequencies from 0.5 to 4 Hz. A regenerator comprised of 25 g of 200 µm spherical Gd powder reached temperature spans of 19.3 K under no applied cooling load and 2.6 K under the maximum applied cooling load of 20 W. The device also achieves a very high specific exergetic cooling power of 73 W L−1 T−1. Results obtained at two different maximum magnetic fields in the same device suggest a powerful new scaling for regenerator performance: the exergetic power quotient. The exergetic power quotient shows a simple scaling of device cooling performance with the amount of active material and the magnetic field strength. This suggests results from a small device correlate to expected performance of a larger regenerator, making the exergetic power quotient a well-suited parameter for evaluating functionality of active magnetic regenerators employing new magnetocaloric materials

Low-force compressive and tensile actuation for elastocaloric heat pumps

The elastocaloric effect underpins a promising solid-state heat pumping technology that, when adopted for commercial and residential applications, can revolutionize the cooling and heating industry due to low environmental impact and substantial energy savings. Known operational demonstration devices based on the elastocaloric effect suffer from low endurance of materials and, in most experimental systems, from large footprints due to bulky actuators required to provide sufficient forces and displacements. We demonstrate a new approach which has the potential to enable a more effective exploitation of the elastocaloric effect by reducing the forces required for actuation. Thin strips of NiTi were incorporated into composite structures with base polymer, such that bending the structures results in either exclusively compression or exclusively tension applied to the elastocaloric strips. The structures allow compression of thin elastocaloric strips without buckling, realize more than 50 % reduction in required forces for a given strain compared with axial loading, and open up a wide range of possibilities for compact, efficient elastocaloric devices

www.dcj.state.co.us/ors

the DCSIP Advisory Board, for financially supporting this evaluation to allow us to meet our legislative mandate to evaluate the Youthful Offender System. We would like to thank all those who assisted us in this research effort. We are especially grateful for the assistance of the administrators and staff of the Youthful Offender System, who spent time talking with us about the program and answering our interview questions. We are particularly grateful to Pam Ploughe who arranged interviews, program observations, and access to other documentation about the program. We are grateful to the many, many other individuals who were interviewed for this project including current and former state legislators, Department of Corrections and Division of Youth Services Staff, and other individuals involved with the program, including those serving offenders in Phase III in the community. Also, we would like to thank the offenders we interviewed and the families of offenders who took the time to provide input through our focus group. These contributions were invaluable to the research. Finally, we would like to thank Heather Cameron, Nicole Hetz, Kerry Lowden, Diane Pasini-Hill, and Suzanne Gonzalez Woodburn from the Office of Research and Statistics for their contributions to the design, data collection and management of this study. Thanks to Linda Harrison for her work with the complicated electronic files. As always, we would like to thank our Divisio

Human monoclonal antibodies against Ross River virus target epitopes within the E2 protein and protect against disease

Ross River fever is a mosquito-transmitted viral disease that is endemic to Australia and the surrounding Pacific Islands. Ross River virus (RRV) belongs to the arthritogenic group of alphaviruses, which largely cause disease characterized by debilitating polyarthritis, rash, and fever. There is no specific treatment or licensed vaccine available, and the mechanisms of protective humoral immunity in humans are poorly understood. Here, we describe naturally occurring human mAbs specific to RRV, isolated from subjects with a prior natural infection. These mAbs potently neutralize RRV infectivity in cell culture and block infection through multiple mechanisms, including prevention of viral attachment, entry, and fusion. Some of the most potently neutralizing mAbs inhibited binding of RRV to Mxra8, a recently discovered alpahvirus receptor. Epitope mapping studies identified the A and B domains of the RRV E2 protein as the major antigenic sites for the human neutralizing antibody response. In experiments in mice, these mAbs were protective against cinical disease and reduced viral burden in multiple tissues, suggesting a potential therapeutic use for humans

PenQuest Volume 5, Number 1

Table of Contents for this Volume: Success by Shatney Maria by Jane O’Neal Intrusions by Mark McBride The Mystery of the Back Porch Light by Nature Johnston Truth and the Violin by Shatney Corporate America by Julie Crowell Pete’s Cafe by Nature Johnston Geranium by Anne Benjamin The Man Who Buried His Books by William Slaughter Erasures by William Slaughter Mind You and other poems by Kate Mathews Coffee in the Tea Room by Kathleen O’Brien The Children by Katharine Rodier Sisters, Reclamation, Not Wanting to Say, “I Told You So,” But… by Kathleen O’Brien Genetics by Kathleen O’Brien The Anguish of Flames by Kathleen O’Brien turning plows by Mark McBride A Valediction for My Father by Jonathan Williams Untitled by Mark Sablow Artificial Portrait by Kevin Christenson Untitled by Latrell Mickler Untitled by Kevin Christenson Galvanistic Ascension by Mark Grisham Power Surge by Mark Grisham Untitled by Lori Kirsbau