PMHS impact response in low and high-speed nearside impacts

Lateral impact tests were performed using seven male post-mortem human subjects (whole, unembalmed cadavers) to further characterize the response of the body, and in particular the force-deflection response of the lower abdomen, to lateral impact. All tests were performed using a dual-sled, side-impact test facility. A multi-segmented impactor was mounted on a sled that was pneumatically accelerated into a second, initially stationary sled on which a cadaver subject was seated facing perpendicular to the direction of impact. Sizes and heights of impactor segments were adjusted for each subject so that forces applied to different anatomic regions including thorax, abdomen, greater trochanter, iliac wing, and thigh could be independently measured on each cadaver. For all tests, the impactor contact surfaces were located in the same vertical plane except that the abdomen plate was offset 5.1 cm toward the subject. Each subject was first impacted on one side of the body using an initial impactor speed of 3 m/s. Following the five of these tests that did not result in injury, the contralateral side of the body was impacted at a speed of either 8 m/s or 10 m/s. The masses of the sleds and the force-deflection characteristics of the energy-absorbing material that acted as the interface between the sleds were set so that the velocity history of the impactor sled matched the average driver door velocity history produced in a series of side NCAP tests. Impactor padding was also selected so that average ATD pelvis and thorax responses from the same series of side NCAP tests were reproduced when the ATD used in these tests was impacted using the average door-velocity history. Results of these tests were used to develop force-deflection response targets for the abdomen, force history response targets for the pelvis (iliac wing and greater trochanter), the midthigh, and the thorax at each of the three impact velocities. Response targets for the lateral acceleration of the pelvis were also developed. Future work will compare side impact ATD responses to these response targets.NHTSA, Human Injury Research Divisionhttp://deepblue.lib.umich.edu/bitstream/2027.42/91957/1/102871.pd

An intelligent CNC machine control system architecture

Intelligent, agile manufacturing relies on automated programming of digitally controlled processes. Currently, processes such as Computer Numerically Controlled (CNC) machining are difficult to automate because of highly restrictive controllers and poor software environments. It is also difficult to utilize sensors and process models for adaptive control, or to integrate machining processes with other tasks within a factory floor setting. As part of a Laboratory Directed Research and Development (LDRD) program, a CNC machine control system architecture based on object-oriented design and graphical programming has been developed to address some of these problems and to demonstrate automated agile machining applications using platform-independent software

Senior Civil Engineering Students’ Views on Sustainability and Resiliency

In recent years, civil engineering education and workforce development have evolved to include a greater emphasis on sustainability and resiliency. Sustainability balances economic, ecological, and societal needs by being responsive to community impact, human health, and the environment. Resilient infrastructure lasts, retaining functional and structural capacity and supporting interconnected transportation, energy, water, and social systems after a distress event. While many undergraduate civil engineering programs address sustainability, it tends to be limited to individual courses, and resiliency concepts are rarely incorporated. To address these shortcomings, we are incorporating sustainability and resiliency conceptual threads and activities throughout our curriculum, from our first-year engineering course through senior design. To understand the effectiveness of this initiative, at the beginning of this project we conducted interviews with senior civil engineering students to collect baseline data on our current students’ views and understanding of sustainability and responsibility. Thematic analysis of these interviews suggests that there is significant variability in students’ understanding of sustainability, with some students recognizing that sustainability involves tradeoffs between economic, environmental, and societal needs, while others tended to conflate sustainability with environmentalism. While students reported encountering sustainability in a portion of their undergraduate courses, they generally did not learn about how sustainability related to much of their technical coursework such as structures, soils, or transportation. Most current students have little conceptual understanding of resiliency which is not surprising given that it is not addressed in any substantial way in our current curriculum. This provides clear evidence of the need for greater exposure to both sustainability and resiliency and understanding the relationship between these practices as part of the undergraduate civil engineering curriculum. By incorporating sustainability and resiliency throughout the undergraduate civil engineering curriculum, students will be better prepared to address these topics as part of their senior design projects, and in their future careers

Measuring Black Hole Spin using X-ray Reflection Spectroscopy

I review the current status of X-ray reflection (a.k.a. broad iron line) based black hole spin measurements. This is a powerful technique that allows us to measure robust black hole spins across the mass range, from the stellar-mass black holes in X-ray binaries to the supermassive black holes in active galactic nuclei. After describing the basic assumptions of this approach, I lay out the detailed methodology focusing on "best practices" that have been found necessary to obtain robust results. Reflecting my own biases, this review is slanted towards a discussion of supermassive black hole (SMBH) spin in active galactic nuclei (AGN). Pulling together all of the available XMM-Newton and Suzaku results from the literature that satisfy objective quality control criteria, it is clear that a large fraction of SMBHs are rapidly-spinning, although there are tentative hints of a more slowly spinning population at high (M>5*10^7Msun) and low (M<2*10^6Msun) mass. I also engage in a brief review of the spins of stellar-mass black holes in X-ray binaries. In general, reflection-based and continuum-fitting based spin measures are in agreement, although there remain two objects (GROJ1655-40 and 4U1543-475) for which that is not true. I end this review by discussing the exciting frontier of relativistic reverberation, particularly the discovery of broad iron line reverberation in XMM-Newton data for the Seyfert galaxies NGC4151, NGC7314 and MCG-5-23-16. As well as confirming the basic paradigm of relativistic disk reflection, this detection of reverberation demonstrates that future large-area X-ray observatories such as LOFT will make tremendous progress in studies of strong gravity using relativistic reverberation in AGN.Comment: 19 pages. To appear in proceedings of the ISSI-Bern workshop on "The Physics of Accretion onto Black Holes" (8-12 Oct 2012). Revised version adds a missing source to Table 1 and Fig.6 (IRAS13224-3809) and corrects the referencing of the discovery of soft lags in 1H0707-495 (which were in fact first reported in Fabian et al. 2009

Pulsations driven by the ε-mechanism in post-merger remnants: First results

Helium-rich subdwarfs are a rare subclass of hot subdwarf stars which constitute a small and inhomogeneous group showing varying degrees of helium enrichment. Only one star, LS IV º14 116 has been found to show multiperiodic luminosity variations. The variability of LS IV º14 116 has been explained as the consequence of nonradial g-mode oscillations, whose excitation is difficult to understand within the frame of the standard κ-mechanism driving pulsations in sdBV stars. In a recent study, we have proposed that the pulsations of LS IV º14 116 might be driven through the ε-mechanism acting in unstable He-burning zones in the interior of the star, that appear before the quiescent He-burning phase. One of the few accepted scenarios for the formation of He-rich subdwarfs is the merger of two He-core white dwarfs. As part of this project, we present a study of the ε-mechanism in post-merger remnants, and discuss the results in the light of the pulsations exhibited by LS IV º14 116.Facultad de Ciencias Astronómicas y Geofísica

Pulsations driven by the ε-mechanism in post-merger remnants: First results

Helium-rich subdwarfs are a rare subclass of hot subdwarf stars which constitute a small and inhomogeneous group showing varying degrees of helium enrichment. Only one star, LS IV º14 116 has been found to show multiperiodic luminosity variations. The variability of LS IV º14 116 has been explained as the consequence of nonradial g-mode oscillations, whose excitation is difficult to understand within the frame of the standard κ-mechanism driving pulsations in sdBV stars. In a recent study, we have proposed that the pulsations of LS IV º14 116 might be driven through the ε-mechanism acting in unstable He-burning zones in the interior of the star, that appear before the quiescent He-burning phase. One of the few accepted scenarios for the formation of He-rich subdwarfs is the merger of two He-core white dwarfs. As part of this project, we present a study of the ε-mechanism in post-merger remnants, and discuss the results in the light of the pulsations exhibited by LS IV º14 116.Facultad de Ciencias Astronómicas y Geofísica

Suppression of inhomogeneous broadening in rf spectroscopy of optically trapped atoms

We present a novel method for reducing the inhomogeneous frequency broadening in the hyperfine splitting of the ground state of optically trapped atoms. This reduction is achieved by the addition of a weak light field, spatially mode-matched with the trapping field and whose frequency is tuned in-between the two hyperfine levels. We experimentally demonstrate the new scheme with Rb 85 atoms, and report a 50-fold narrowing of the rf spectrum

Abiotic Cycles Mediate the Strength of Cross-Boundary Consumption Within Coastal Food Webs

Understanding the effect of habitat edges on species interactions (e.g. predation) is critical for determining landscape-scale patterns in productivity and the structuring of communities in an ever-changing environment. Both abiotic cycles and habitat structure can mediate faunal movements across habitat edges and determine predators’ ability to access prey across both space and time. To quantify the effects of cyclical abiotic factors and habitat structure on consumer-resource dynamics across habitat boundaries at the land-sea interface, four complementary studies were conducted. Marsh periwinkles Littoraria irrorata were tethered within salt marshes of varying tidal amplitude, at 3 distances from the marsh edge, and assessed for predation after 24 h. Nekton catch rate was assessed with fyke net sampling as a proxy for predator utilization of the marsh platform. Consumption rates were positively correlated with tidal amplitude and proximity to the seaward marsh edge, and there was also a slight positive relationship between tidal amplitude and nekton access to the marsh. Tidal amplitude was positively correlated with Spartina alterniflora shoot density and negatively correlated with shoot height. Therefore, to separate the effects of habitat structure from tidal forcing, independent manipulations of shoot density and shoot height were conducted. We found that the signal of local habitat structure on consumption rates appears to be secondary to the effects of abiotic cycles on consumption. Disentangling the interactions between abiotic cycles and biotic structure of ecosystems across ecological boundaries is key to understanding both the strengths of species interactions and the mediation of cross-boundary energy flow