Discrete layer finite element modeling of anisotropic laminated shells based on a refined semi - inverse mixed displacement field formulation

This paper concerns the finite element (FE) modeling of anisotropic laminated shells. A discretelayer approach is employed in this work and a single layer is first considered and isolatedfrom the multilayer shell structure. The weak form of the governing equations of theanisotropic single layer of the multilayer shell is derived with Hamiltons principle using amixed (stresses/displacements) definition of the displacement field, which is obtained througha semi-inverse (stresses/strains-displacements) approach. Results from 3-D elasticity solutionsare used to postulate adequate definitions of the out-of-plane shear stress components, which,in conjunction with the Reissner-Mindlin theory (or first order shear deformation theory) de-finitions of the shell in-plane stresses, are utilized to derive the mixed displacement field.Afterward, the single layer shell FE is regenerated to a 3-D form, which allows interlayerdisplacements and out-of-plane stresses continuity between adjacent interfaces of different layersto be imposed, and a multilayer shell FE is obtained by assembling, at an elemental FElevel, all the regenerated single layer FE contributions. A fully refined shell theory, wheredisplacement and full out-of-plane stresses continuity and homogeneous stress conditions onthe top and bottom surfaces are assured, is conceptually proposed, and a partially refined shelltheory, where the out-of-plane normal stress continuity is relaxed and a plane stress state is considered,is developed and used to derive a FE solution for segmented multilayer doubly-curvedanisotropic shells

Experiment K-6-22. Growth hormone regulation, synthesis and secretion in microgravity. Part 1: Somatotroph physiology. Part 2: Immunohistochemical analysis of hypothalamic hormones. Part 3: Plasma analysis

The objectives of the 1887 mission were: (1) to determine if the results of the SL-3 pituitary gland experiment (1) were repeatable; and (2) to determine what effect a longer mission would have on the rat pituitary gland growth hormone (GH) system. In the 1887 experiment two issues were considered especially important. First, it was recognized that cells prepared from individual rat pituitary glands should be considered separately so that the data from the 5 glands could be analyzed in a statistically meaningful way. Second, results of the SL-3 flight involving the hollow fiber implant and HPLC GH-variant experiments suggested that the biological activity of the hormone had been negatively affected by flight. The results of the 1887 experiment documented the wisdom of addressing both issues in the protocol. Thus, the reduction in secretory capacity of flight cells during subsequent extended cell culture on Earth was documented statistically, and thereby established the validity of the SL-3 result. The results of both flight experiments thus support the contention that there is a secretory lesion in pituitary GH cells of flight animals. The primary objective of both missions was a clear definition of the effect of spaceflight on the GH cell system. There can no longer be any reasonable doubt that this system is affected in microgravity. One explanation for the reason(s) underlying the better known effects of spaceflight on organisms, viz. changes in bone, muscle and immune systems may very well rest with such changes in bGH. In spite of the fact that rats in the Cosmos 1887 flight were on Earth for two days after flight, the data show that the GH system had still not recovered from the effects of flight. Many questions remain. One of the more important concerns the GRF responsiveness of somatotrophs after flight. This will be tested in an upcoming experiment

Durability of CSP Materials

Durability of CSP materials. Presentation for 4th SYMPOSIUM IPES by Teresa Diamantino

Actigraph calibration in obese/overweight and type 2 Diabetes Mellitus middle-aged to old adult patients

Background: Several methods exist to asses and control physical intensity levels of subjects engaged in physical activities programs, accelerometry is a method that could be easily used in the field. The purposes were: to calibrate Actigraph in middle-aged to old obese/overweight and DM2 adult patients; and to determine the threshold counts for sedentary, light, moderate, and vigorous physical activity (PA). Methods: Sample comprise 26 participants (62.6 ± 6.5 years of age) of both gender. Counts and VO2 were simultaneously assessed during: resting, seating, standing, walking at 2.5 km·h–1, 5 km·h–1, and 6 km·h–1. A hierarchical linear model was used to derive a regression equation between MET and counts. Receiver operating characteristics (ROC) analysis was used to define thresholds for PA levels. Results: The regression equation was: MET = 1.388400490262 + 0.001312683420044 (counts·min–1), r = .867. The threshold counts for sedentary-light, light-moderate and moderate-vigorous PA were: 200, 1240, 2400 counts·min–1 respectively. Conclusion: The Actigraph is a valid and useful device for the assessment of the amount of time spent in each PA intensity levels in obese/overweight and DM2 middle-aged to old adult patients

Experiment K-6-16. Morphological examination of rat testes. The effect of Cosmos 1887 flight on spermatogonial population and testosterone level in rat testes

Testes from rats flown on Cosmos 1887 for twelve and a half days were compared to basal control, synchronous control and vivarium maintained rats. When the mean weights of flight testes, normalized for weight/100 gms, were compared to the vivarium controls they were 6.7 percent lighter. Although the flight testes were lighter than the synchronous, the difference is not significant. Counts of spermatogonial cells from 5 animals in each group revealed a 4 percent decrease in flight compared to vivarium controls. In both cases the t-Test significance was less than 0.02. The serum testosterone levels of all animals (flight, synchronous and vivarium) were significantly below the basal controls

Net heart rate to prescribe physical activity in middle-aged to older active adults

This study had a twofold purpose: i) to develop a regression equation to estimate metabolic equivalent (MET) in walk/run by heart rate increment above rest (NetHR), and; ii) to determine NetHR thresholds for light, moderate, and vigorous physical activity (PA), from middle aged to elderly. Sample 1 (prediction sample) comprised 39 subjects (19 male and 20 female), with 58.2 ± 11.0 years old. Sample 2 (validation sample) comprised 40 subjects (18 male and 22 female) with 63.3 ± 7.0 years old. Each participant did the following activities in sequence, a 15min rest period in supine position, walk at 3km/h, walk at 4.5km/h, and walk at 6km/h, for 6 min at each walk velocity interval. The oxygen up-take (VO2) and heart rate (HR) were continuously and simultaneously assessed. A hierarchical linear model was used to analyze the relationship between metabolic equivalent (MET) and NetHR. The regression equation for MET prediction was: MET = 1.265780 + 0.109479 NetHR. The NetHR thresholds (upper limit) for light, moderate and vigorous PA were 16 and 35 and 70 bpm, respectively. NetHR is a practical, valid and non-invasive method to prescribe physical activity, taking in account individual characteristics (HR at rest combined with NetHR) in middle-aged to older adults

Dismantling the Walls: Peer-Facilitated Inter-Race/Ethnic Dialogue Processes and Experiences

Also PCMA Working Paper #49.http://deepblue.lib.umich.edu/bitstream/2027.42/51296/1/532.pd

Post-fire diversity and abundance in pine and eucalipt stands in Portugal: effects of biogeography, topography, forest type and post-fire management

This study concerned the mid-term regeneration of the woody understory vegetation of pure and mixed stands of Pinus pinaster Ait. and Eucalyptus globulus Labill. in northern and central Portugal following wildfires in 2005 and 2006. Pine and eucalypt stands are the most widespread and most fire-prone forest types in Portugal. The main aim was to investigate the importance of biogeography, topography, forest type and post-fire management operations in explaining the patterns in shrub diversity (species richness) and abundance (cover). To this end, 284 study sites in four distinct biogeographic regions were sampled 5 to 7 years following the last wildfire. At each site, the presence and cover of individual shrub species were estimated using 4 sub-plot of approximately 10 m2 each. The entire data set was analyzed by means of GLM using a total of seven explanatory variables: biogeographic region, forest type, three types post-fire management operations (soil tillage, tree harvesting, and shrub clearance), and two topographic variables (slope angle and elevation). The GLM analysis was also done for the individual biogeographic regions. Biogeographic region and slope steepness were key factors explaining shrub species richness, albeit the role of slope angle was possibly linked to the intensity of past land use. Biogeographic region equally played a significant role in explaining the cover of all shrubs together as well as of the shrubs of Leguminosae and Cistaceae. All three types of post-fire management operations appeared to hamper the recovery of resprouters and Leguminosae, whereas just tree harvesting and shrub clearance (but not soil tillage) negatively affected the cover of seeder species. These impacts of post-fire management operations had a noticeable region-specific component, being more relevant in the less productive biogeographic regions. Also the role of forest type depended strongly on biogeographic region. It was only significant in the South Mediterranean region, where pine plantations had a higher total shrub cover as well as higher covers of seeders and Cistaceae. Possibly, however, this significant role of forest type could be due to the lower incidence of shrub clearance in the pine standsinfo:eu-repo/semantics/publishedVersio

High-temperature corrosion performance of austenitic stainless steels type AISI 316L and AISI 321H, in molten solar salt

ABSTRACT: The corrosion rates of AISI 316L and AISI 321H austenitic stainless steel, immersed in a stagnant isothermal mixture of 60% NaNO3 and 40% KNO3 molten salt at 550 degrees C in atmospheric air are 8.6 and 9.0 mu m/yr, respectively. The corrosion mechanism was proposed by recording the weight changes of the steel coupons at different time intervals up to 3000 h, and by the characterization of multilayer oxide scales formed on the steel surface. Multilayers made of different oxides, mainly Fe2O3 and Fe3O4, are the principal scale products. At 3000 h, the thickness of the scale layer formed on AISI 321H (7.5 +/- 2.9 mu m) is slightly higher than the one formed at the AISI 316L (6.9 +/- 2.1 mu m). This small difference might reflect the partial spallation of the corrosion layer on AISI 321H, which is seen for times longer than 1000 h. A minimal change of the composition of the molten nitrate salt is observed in time and is predominantly due to the appearance of soluble chromate products and nitrite compounds (0.004 wt% and 1.4 wt% at 3000 h, respectively). The observed corrosion behaviour of these alloys shows that they are good candidate for usage as containers of molten nitrate salts in the thermal energy storage (TES) system for a CSP plant.info:eu-repo/semantics/publishedVersio