The Effect of Layer Orientation on the Tensile Properties of Net Shape Parts Fabricated in Stereolithography

Stereolithographic technologies create parts in thermoset plastic polymeric mixtures of acrylates and epoxies. In order to predict the mechanical behavior of these parts, it is critical to understand the effects that build parameters have on the final properties of the polymer. Using a statistics based approach, the build parameters of layer orientation, layer thickness, and resin class are used as inputs. The response variables, peak stress, elongation at break and Young’s modulus (modulus of elasticity), are examined using the methodology specified in ASTM D638- 01 with modifications as noted. An initial test in Somos 8120 showed the surprising (and statistically significant) result that load bearing capability in the build direction was greater than in the in-layer direction. Additional tensile tests in Somos 8120 and Vantico SL-5510 were undertaken to verify this result, and determine if this effect is present across different classes of resin. This report details the rationale behind this experiment, presents the results to date, and outlines future efforts.Mechanical Engineerin

Optimizing Student Team Skill Development Using Evidence-Based Strategies

The critical importance of effective teamwork in engineering is widely recognized. Surprisingly, however, relatively little is known about how to develop teamwork skills in higher education classes, including what factors contribute to effective teamwork, their relative importance in a team\u27s overall performance, and the underlying individual and interpersonal dynamics. Increasing numbers of engineering instructors are adopting instructional practices relying on teamwork, yet many instructors simply form student teams and hope the members individually and collectively learn on their own how to work in teams and succeed in their task(s). Instructors do this because they do not have guidance for a better approach. This research project aims to address this gap in faculty knowledge. The empirical studies conducted as part of this project build on research in engineering education, cognitive psychology, social psychology, and other fields in a coordinated large-scale research project that will provide faculty with needed knowledge and tools to ensure that students learn team skills. The research team is conducting seven separate studies measuring the impact of teamwork training, experience working in teams, practice rating the teamwork of fictitious team members, and giving and receiving peer feedback. The research is measuring each of these effects in real teams on three learning outcomes: improved teamwork knowledge, improved ability to evaluate teamwork, and improved ability to function effectively in teams. These studies will result in practical recommendations for time-pressed faculty to implement

Health and Environmental Effects Document on Geothermal Energy -- 1982 update

We assess several of the important health and environmental risks associated with a reference geothermal industry that produces 21,000 MWe for 30 y (equivalent to 20 x 10{sup 18} J). The analyses of health effects focus on the risks associated with exposure to hydrogen sulfide, particulate sulfate, benzene, mercury, and radon in air and arsenic in food. Results indicate that emissions of hydrogen sulfide are likely to cause odor-related problems in 29 of 51 geothermal resources areas, assuming that no pollution controls are employed. Our best estimates and ranges of uncertainty for the health risks of chronic population exposures to atmospheric pollutants are as follows (risks expressed per 10{sup 18} J of electricity): particulate sulfate, 44 premature deaths (uncertainty range of 0 to 360); benzene, 0.15 leukemias (range of 0 to 0.51); elemental mercury, 14 muscle tremors (range of 0 to 39); and radon, 0.68 lung cancers (range of 0 to 1.8). The ultimate risk of fatal skin cancers as the result of the transfer of waste arsenic to the general population over geologic time ({approx} 100,000 y) was calculated as 41 per 10{sup 18} J. We based our estimates of occupational health effects on rates of accidental deaths together with data on occupational diseases and injuries in surrogate industries. According to our best estimates, there would be 8 accidental deaths per 10{sup 18} J of electricity, 300 cases of occupational diseases per 10{sup 18} J, and 3400 occupational injuries per 10{sup 18}J. The analysis of the effects of noncondensing gases on vegetation showed that ambient concentrations of hydrogen sulfide and carbon dioxide are more likely to enhance rather than inhibit the growth of plants. We also studied the possible consequences of accidental releases of geothermal fluids and concluded that probably less than 5 ha of land would be affected by such releases during the production of 20 x 10{sup 18} J of electricity. Boron emitted from cooling towers in the Imperial Valley was identified as a potential source of crop damage. Our analyses, however, showed that such damage is unlikely. Finally, we examined the nonpollutant effects of land subsidence and induced seismicity. Land subsidence is possible around some facilities, but surface-related damage is not expected to be great. Induced seismic events that have occurred to date at geothermal resource areas have been nondestructive. It is not possible to predict accurately the risk of potentially destructive events, and more research is needed in this area

SMARTER Teamwork: System for Management, Assessment, Research, Training, Education, and Remediation for Teamwork

SMARTER Teamwork: System for Management, Assessment, Research, Training, Education, and Remediation for TeamworkThe rapid adoption of Team-Maker and the Comprehensive Assessment of Team MemberEffectiveness (CATME) tools for team formation and peer evaluation make it possible to extendtheir success to have a significant impact on the development of team skills in higher education.The web-based systems have been used by more than 110,000 students of more than 2400faculty at more than 500 institutions internationally—the figure below shows the growth of theuser base. 2400 The system has had 113,373 unique student users. 2200 Fitted curves are third order. 2000 1800 Faculty and staff 1600 1400 1200 Number of 1000 users 800 Institutions 600 400 Aug Oct. 2005 2012 200 0 0 1 2 3 4 5 6 7 Years since software was releasedThis paper and its accompanying poster will describe strategies for broadening the scope of thosetools into a complete system for the management of teamwork in undergraduate education. TheSystem for the Management, Assessment, Research, Training, Education, and Remediation ofTeamwork (SMARTER Teamwork) has three specific goals: 1) to equip students to work inteams by providing them with training and feedback, 2) to equip faculty to manage student teamsby providing them with information and tools to facilitate best practices, and 3) to equipresearchers to understand teams by broadening the system’s capabilities to collect additionaltypes of data so that a wider range of research questions can be studied through a secureresearcher interface. The three goals of the project support each other in hierarchical fashion:research informs faculty practice, faculty determine the students’ experience, which, if wellmanaged based on research findings, equips students to work in teams. Our strategies forachieving these goals are based on a well-accepted training model that has five elements:information, demonstration, practice, feedback, and remediation.The paper that will be submitted and the poster presented at the conference will focus on newfeatures of the system, the development of training materials, and the deployment of a partnerwebsite that shares information about the SMARTER tools for teamwork and provides basicinformation about teamwork and team management

Resolving fine-scale population structure and fishery exploitation using sequenced microsatellites in a northern fish

Funding Information Natural Sciences and Engineering Research Council of Canada (NSERC) Strategic Project Atlantic Canada Opportunities Agency and Department of Tourism, Culture, Industry and Innovation grants allocated to the Labrador Institute (MC) Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Genomics Research and Development Initiative (GRDI) Weston Family AwardPeer reviewedPublisher PD

Inclusive cross section and double helicity asymmetry for pi^0 production in p+p collisions at sqrt(s) = 62.4 GeV

The PHENIX experiment presents results from the RHIC 2006 run with polarized proton collisions at sqrt(s) = 62.4 GeV for inclusive pi^0 production at mid-rapidity. Unpolarized cross section results are measured for transverse momenta p_T = 0.5 to 7 GeV/c. Next-to-leading order perturbative quantum chromodynamics calculations are compared with the data, and while the calculations are consistent with the measurements, next-to-leading logarithmic corrections improve the agreement. Double helicity asymmetries A_LL are presented for p_T = 1 to 4 GeV/c and probe the higher range of Bjorken_x of the gluon (x_g) with better statistical precision than our previous measurements at sqrt(s)=200 GeV. These measurements are sensitive to the gluon polarization in the proton for 0.06 < x_g < 0.4.Comment: 387 authors from 63 institutions, 10 pages, 6 figures, 1 table. Submitted to Physical Review D. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

Cross sections and double-helicity asymmetries of midrapidity inclusive charged hadrons in p+p collisions at sqrt(s)=62.4 GeV

Unpolarized cross sections and double-helicity asymmetries of single-inclusive positive and negative charged hadrons at midrapidity from p+p collisions at sqrt(s)=62.4 GeV are presented. The PHENIX measurements for 1.0 < p_T < 4.5 GeV/c are consistent with perturbative QCD calculations at next-to-leading order in the strong coupling constant, alpha_s. Resummed pQCD calculations including terms with next-to-leading-log accuracy, yielding reduced theoretical uncertainties, also agree with the data. The double-helicity asymmetry, sensitive at leading order to the gluon polarization in a momentum-fraction range of 0.05 ~< x_gluon ~< 0.2, is consistent with recent global parameterizations disfavoring large gluon polarization.Comment: PHENIX Collaboration. 447 authors, 12 pages, 5 figures, 5 tables. Submitted to Physical Review

Inclusive cross section and single-transverse-spin asymmetry for very forward neutron production in polarized p+p collisions at sqrt(s)=200 GeV

The energy dependence of the single-transverse-spin asymmetry, A_N, and the cross section for neutron production at very forward angles were measured in the PHENIX experiment at RHIC for polarized p+p collisions at sqrt(s)=200 GeV. The neutrons were observed in forward detectors covering an angular range of up to 2.2 mrad. We report results for neutrons with momentum fraction of x_F=0.45 to 1.0. The energy dependence of the measured cross sections were consistent with x_F scaling, compared to measurements by an ISR experiment which measured neutron production in unpolarized p+p collisions at sqrt(s)=30.6--62.7 GeV. The cross sections for large x_F neutron production for p+p collisions, as well as those in e+p collisions measured at HERA, are described by a pion exchange mechanism. The observed forward neutron asymmetries were large, reaching A_N=-0.08+/-0.02 for x_F=0.8; the measured backward asymmetries, for negative x_F, were consistent with zero. The observed asymmetry for forward neutron production is discussed within the pion exchange framework, with interference between the spin-flip amplitude due to the pion exchange and nonflip amplitudes from all Reggeon exchanges. Within the pion exchange description, the measured neutron asymmetry is sensitive to the contribution of other Reggeon exchanges even for small amplitudes.Comment: 383 authors, 16 pages, 18 figures, 6 tables. Submitted to Phys. Rev. D. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

Identified charged hadron production in p+p collisions at sqrt(s)=200 and 62.4 GeV

Transverse momentum distributions and yields for $\pi^{\pm}$, $K^{\pm}$, $p$ and $\bar{p}$ in $p+p$ collisions at $\sqrt{s}$=200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC). These data provide important baseline spectra for comparisons with identified particle spectra in heavy ion collisions at RHIC. We present the inverse slope parameter $T_{\rm inv}$, mean transverse momentum $$ and yield per unit rapidity $dN/dy$ at each energy, and compare them to other measurements at different $\sqrt{s}$ in $p+p$ and $p+\bar{p}$ collisions. We also present the scaling properties such as $m_T$ scaling, $x_T$ scaling on the $p_T$ spectra between different energies. To discuss the mechanism of the particle production in $p+p$ collisions, the measured spectra are compared to next-to-leading-order or next-to-leading-logarithmic perturbative quantum chromodynamics calculations.Comment: 431 authors from 62 institutions, 32 pages, 23 figures, and 18 tables. Submitted to Physical Review C. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm