Results of the Round Robin on opening-load measurement conducted by ASTM Task Group E24.04.04 on Crack Closure Measurement and Analysis

An experimental Round Robin on the measurement of the opening load in fatigue crack growth tests was conducted on Crack Closure Measurement and Analysis. The Round Robin evaluated the current level of consistency of opening load measurements among laboratories and to identify causes for observed inconsistency. Eleven laboratories participated in the testing of compact and middle-crack specimens. Opening-load measurements were made for crack growth at two stress-intensity factor levels, three crack lengths, and following an overload. All opening-load measurements were based on the analysis of specimen compliance data. When all of the results reported (from all participants, all measurement methods, and all data analysis methods) for a given test condition were pooled, the range of opening loads was very large--typically spanning the lower half of the fatigue loading cycle. Part of the large scatter in the reported opening-load results was ascribed to consistent differences in results produced by the various methods used to measure specimen compliance and to evaluate the opening load from the compliance data. Another significant portion of the scatter was ascribed to lab-to-lab differences in producing the compliance data when using nominally the same method of measurement

The Joint Efficient Dark-energy Investigation (JEDI): Measuring the cosmic expansion history from type Ia supernovae

JEDI (Joint Efficient Dark-energy Investigation) is a candidate implementation of the NASA-DOE Joint Dark Energy Mission (JDEM). JEDI will probe dark energy in three independent methods: (1) type Ia supernovae, (2) baryon acoustic oscillations, and (3) weak gravitational lensing. In an accompanying paper, an overall summary of the JEDI mission is given. In this paper, we present further details of the supernova component of JEDI. To derive model-independent constraints on dark energy, it is important to precisely measure the cosmic expansion history, H(z), in continuous redshift bins from z \~ 0-2 (the redshift range in which dark energy is important). SNe Ia at z > 1 are not readily accessible from the ground because the bulk of their light has shifted into the near-infrared where the sky background is overwhelming; hence a space mission is required to probe dark energy using SNe. Because of its unique near-infrared wavelength coverage (0.8-4.2 microns), JEDI has the advantage of observing SNe Ia in the rest frame J band for the entire redshift range of 0 < z < 2, where they are less affected by dust, and appear to be nearly perfect standard candles. During the first year of JEDI operations, spectra and light curves will be obtained for ~4,000 SNe Ia at z < 2. The resulting constraints on dark energy are discussed, with special emphasis on the improved precision afforded by the rest frame near-infrared data.Comment: 8 pages, accepted for publication in SPIE proceeding

Contractile Filament Stress: Comparison of Different Disease States in Man

Author Institution: Department of Engineering and Department of Physiology, Wright State UniversityCardiac catheterization data on 39 patients was classified in 5 cardiovascular groups: normal, compensated volume overload, decompensated volume overload, compensated pressure overload, and congestive cardiomyopathy. Both the Lagrangian stress and contractile filament stress for the circumferential axis and the longitudinal axis were computed over a complete cardiac cycle. Contractile filament stress was 24% higher than Lagrangian stress in the circumferential direction, and 43% higher than Lagrangian stress in the longitudinal direction. The percent difference in stress between the contractile filament stress and Lagrangian stress was greatest for patients with pressure overload, and least for patients with compensated volume overload. No significant difference in calculated wall stress was noted between the normal group and the 4 pathological groups. Circumferential velocity of the contractile element occurring at peak stress was plotted as a function of peak contractile filament stress and patients with compensated pressure overload exhibited high values of both velocity and peak stress. Patients with congestive cardiomyopathy showed low values of both velocity and peak stress. Circumferential velocity of the contractile element occurring throughout the cardiac cycle was plotted as a function of both the instantaneous Lagrangian stress and the instantaneous contractile filament stress, resulting in 2 stress-velocity curves for each patient. The value of the maximum velocity extrapolated from either stress-velocity curve was approximately the same, but the maximum stress extrapolated from the contractile filament stress-velocity curve was significantly higher than the maximum stress extrapolated from the Lagrangian stressvelocity curve. The product of peak contractile filament stress in the circumferential direction times heart rate was a clinically useful index of myocardial oxygen consumption, and predicted a lower rate of oxygen consumption than did the product of peak developed stress times heart rate

New Clock Comparison Searches for Lorentz and CPT Violation

We present two new measurements constraining Lorentz and CPT violation using the Xe-129 / He-3 Zeeman maser and atomic hydrogen masers. Experimental investigations of Lorentz and CPT symmetry provide important tests of the framework of the standard model of particle physics and theories of gravity. The two-species Xe-129 / He-3 Zeeman maser bounds violations of CPT and Lorentz symmetry of the neutron at the 10^-31 GeV level. Measurements with atomic hydrogen masers provide a clean limit of CPT and Lorentz symmetry violation of the proton at the 10^-27 GeV level.Comment: 11 pages, 5 figures. To appear in the Proceedings of the 3rd International Symposium on Symmetries in Subatomic Physic

Cross-disciplinary Teaching of both Computer Forensics Students and Law Students Using Peer-Assessment in a Simulated Expert Witness Scenario

This paper describes a novel initiative of the Computing and Information Systems (CIS) Dept in conjunction with the Law Dept at the University of Greenwich. Postgraduate CIS computer forensics students, as part of their assessment, present their findings from a forensics investigation in front of a lecturer and up to five law students in a simulated expert witness testimony scenario. The law students are permitted to ask questions of the computer forensics students and eventually to give their assessment of the student’s witness evidence and presentation. This approach was devised to encompass several pertinent pedagogic issues. Firstly, it is cross-disciplinary, combining as it does, input from two very different departments – an initiative that brings together not only students but also staff who would not otherwise meet. Secondly, it involves the use of practical social/professional skills for both sets of students, as the computer forensics students must present their findings with the skills required of an expert witness in a court setting while the law students must act as cross-examining counsel. Thirdly, this exercise involves the law students assessing the performance of the computer forensics students – an application of peer-assessment that heightens the involvement of both sets of students. Lastly, both sets of students are themselves graded, the computer students by their own forensics lecturer and the law students by their law lecturer, according to their performance in this exercise. The findings from questionnaires sent out to both computer and law students were extremely positive. Both sets felt that they had benefited from the experience and that it would aid their further studies and professional development in their respective areas. It is the opinion of the C-SAFE forensics-law collaborative team that this approach represents an educational innovation in its use of cross-disciplinary problem-solving and peer-assessment in a growing and increasingly significant domain worldwide (cyber forensics)