A Finite Element Analysis of High Temperature Fatigue and Creep at a Stress Concentration.

The Bodner-Partom model of nonlinear time-dependent material behavior was incorporated into a finite element code to predict the strain response at the notch root of an Inconel 718 specimen subjected to cyclic tension-compression at 649(DEGREES)C. A numerical minimization technique was developed to establish the parameters in the Bodner-Partom model. This technique was applied to creep and stress strain data obtained from button-head test specimens tested at 649(DEGREES)C. These parameters were found to be in general close agreement with those obtained by other investigators. The test specimen for the experimental phase of this research was double notched with an elastic stress concentration factor of 1.94. It was subjected to cyclic plastic loads at 649(DEGREES)C which were large enough to generate plastic deformation at the notch root on the tensile portion of the cycle. This behavior was then predicted by incorporating the Bodner-Partom model into a finite element code. The predicted strain response and the experimentally measured (using a laser-based technique) strain response agreed reasonably well

Genes Encoding Flower- and Root-Specific Functions Are More Resistant to Fractionation Than Globally Expressed Genes in Brassica rapa

Like many angiosperms, Brassica rapa underwent several rounds of whole genome duplication during its evolutionary history. Brassica rapa is particularly valuable for studying genome evolution because it also experienced whole genome triplication shortly after it diverged from the common ancestor it shares with Arabidopsis thaliana about 17-20 million years ago. While many B. rapa genes appear resistant to paralog retention, close to 50% of B. rapa genes have retained multiple, paralogous loci for millions of years and appear to be multi-copy tolerant. Based on previous studies, gene function may contribute to the selective pressure driving certain genes back to singleton status. It is suspected that other factors, such as gene expression patterns, also play a role in determining the fate of genes following whole genome triplication. Published RNA-seq data was used to determine if gene expression patterns influence the retention of extra gene copies. It is hypothesized that retention of genes in duplicate and triplicate is more likely if those genes are expressed in a tissue-specific manner, as opposed to being expressed globally across all tissues. This study shows that genes expressed specifically in flowers and roots in B. rapa are more resistant to fractionation than globally expressed genes following whole genome triplication. In particular, there appears to have been selection on genes expressed specifically in flower tissues to retain higher copy numbers and for all three copies to exhibit the same flower-specific expression pattern. Future research to determine if these observations in Brassica rapa are consistent with other angiosperms that have undergone recent whole genome duplication would confirm that retention of flower-specific-expressed genes is a general feature in plant genome evolution and not specific to B. rapa

Gas tungsten arc welding in a microgravity environment: Work done on GAS payload G-169

GAS payload G-169 is discussed. G-169 contains a computer-controlled Gas Tungsten Arc Welder. The equipment design, problem analysis, and problem solutions are presented. Analysis of data gathered from other microgravity arc welding and terrestrial Gas Tungsten Arc Welding (GTAW) experiments are discussed in relation to the predicted results for the GTAW to be performed in microgravity with payload G-169

Material property for designing, analyzing, and fabricating space structures

An analytical study was made of plasma assisted bullet projectile. The finite element analysis and the micro-macromechanic analysis was applied to an optimum design technique for the multilayered graphite-epoxy composite projectile that will achieve hypervelocity of 6 to 10 Km/s. The feasibility was determined of dialectics to monitor cure of graphite-epoxies. Several panels were fabricated, cured, and tested with encouraging results of monitoring the cure of graphite-epoxies. The optimum cure process for large structures was determined. Different orientation were used and three different curing cycles were employed. A uniaxial tensile test was performed on all specimens. The optimum orientation with the optimum cure cycle were concluded

Location effects of passive damping material in cross-ply laminates on natural frequency and mode shape

This study presents an experimental investigation of the free vibration of cantilevered composite laminated plates with embedded passive damping material at different stages. A total of five composite laminated plates are considered. The lay-up sequences for the five composite laminated plates with and without two embedded layers of passive damping material are [90°/0°/90°/0°]s, [90°/0°/90°/0°/d]s, [90°/0°/90°/d/0°]s, [90°/0°/d/90°/0°]s, and [90°/d/0°/90°/0°]s. The passive damping material employed is a 3M material, SJ-2015 ISD 112, with peak damping properties in the ambient temperature range of 32°F to 140°F. The composite material used is a carbon fiber (977-2)/epoxy resin (IM7). The effect of the passive damping system employed in this study for the composite plates are discussed. Modal testing is performed on these plates to determine resonant frequencies, amplitude and mode shape information. The study included white noise and sinusoidal dynamic testing techniques, a PC computer based data acquisition system, and a virtual instrument dynamic analysis. The different locations of the passive damping material in the cross-ply laminated plates resulted in degradation effects on the natural frequency, damping and mode of shape

EMERGENCY TROLLEYS: AVAILABLE AND MAINTAINED, BUT ARE THEIR LOCATIONS KNOWN? – CLOSING THE LOOP

Emergency trolleys are developed and placed in strategic locations to improve the efficiency of the medical teams‘ response to emergencies. In order to close the loop on a previous audit, conducted a year earlier, a second survey was performed to assess the team of Anaesthetists‘ knowledge on the presence and location of those trolleys at the Victoria Ambulatory Care Hospital in Glasgow, Scotland. The results highlighted a considerable deficiency in the knowledge of those trolleys‘ locations, in both surveys. We suggest that similar surveys should be conducted as part of regular audits in all units and should include all staff involved in such emergencies. We also propose new approaches to tackle the problem and help improve the staff knowledge for quick and easy access; thus avoiding delays in critical care management

Hybrid Damping System for an Electronic Equipment Mounting Shelf

The objective of this study was to design and construct a vibration control system for an electronic equipment shelf to be evaluated in the NASA Dryden FTF-11. The vibration control system was a hybrid system which included passive and active damping techniques. Passive damping was fabricated into the equipment shelf using ScothDamp(trademark) damping film and aluminum constraining layers. Active damping was achieved using a two channel active control circuit employing QuickPack(trademark) sensors and actuators. Preliminary Chirp test results indicated passive damping smoothed the frequency response while active damping reduced amplitudes of the frequency response for most frequencies below 500Hz

Hybrid Damping System for an Electronic Equipment Mounting Shelf

The objective of this study was to design and construct a vibration control system for an electronic equipment shelf to be evaluated in the NASA Dryden FTF-II. The vibration control system was a hybrid system which included passive and active damping techniques. Passive damping was fabricated into the equipment shelf using ScothDamp(trademark) damping film and aluminum constraining layers. Active damping was achieved using a two channel active control circuit employing QuickPack(trademark) sensors and actuators. Preliminary Chirp test results indicated passive damping smoothed the frequency response while active damping reduced amplitudes of the frequency response for most frequencies below 500Hz

Researching corporate social responsibility in the Middle East - the current state and future directions

Corporate social responsibility (CSR) has the potential to yield economic and social value in the Middle East (ME), especially given the current high environmental flux in the region. Although much scholarly has been paid to CSR issues, a key question remains about how to operate responsibly in the ME, particularly since institutional environments and stakeholders’ needs vary across ME states. The purpose of this paper is to provide a systematic review of the current state of CSR in the ME. We identify thirty-eight articles that are most pertinent to CSR in the ME and examine the main theoretical frameworks, methodologies, trajectories for further conceptual development, gaps where new research pathways need to be created and also future research questions. From the systematic review, we reveal how attention on CSR in the ME is slowly gaining traction. A snapshot of the gaps identified include the collaboration between business and NGOs, the impact of stakeholders and institutions on CSR, the impact of political and economic crisis on CSR and the influence of individualistic characteristics shaping managers’ CSR behaviour. In addition to such gaps, we present an agenda for future research

Lessons Learned After 760 Neurointerventions via the Upper Extremity Vasculature: Pearls and Pitfalls.

BACKGROUND: The radial approach has been gaining more widespread use by neurointerventionalists fueled by data from the cardiology literature showing better safety and overall reduced morbidity. OBJECTIVE: To present our institution\u27s experience with the radial approach for neuroendovascular interventions in 614 consecutive patients who underwent a cumulative of 760 procedures. METHODS: A retrospective analysis was performed and identified neuroendovascular procedures performed via the upper extremity vasculature access site. RESULTS: Amongst 760 procedures, 34.2% (260) were therapeutic, and 65.7% (500) were nontherapeutic angiograms. Access sites were 71.5% (544) via a conventional radial artery, 27.8% (211) via a distal radial artery, 0.5% (4) via an ulnar artery, and 0.1% (1) via the brachial artery. Most of the procedures (96.9%) were performed via the right-sided (737), 2.9% (22) via the left-sided, and 0.1% (1) via a bilateral approach. Major access site complications occurred at a rate of 0.9% (7). The rate of transfemoral conversion was 4.7% (36). There was a statistically higher incidence of transfemoral conversion when repeat procedures were performed using the same access site. Also, there was no significant difference between nontherapeutic procedures performed using the right and left radial access, and conventional versus distal radial access. Procedural metrics improved after completion of 14 procedures, indicating a learning curve that should be surpassed by operators to reach optimal outcomes. CONCLUSION: Radial artery catheterization is a safe and effective means of carrying out a wide range of neuroendovascular procedures associated with excellent clinical outcomes and an overall low rate of periprocedural complications