Multibody modeling and verification

A summary of a ten week project on flexible multibody modeling, verification and control is presented. Emphasis was on the need for experimental verification. A literature survey was conducted for gathering information on the existence of experimental work related to flexible multibody systems. The first portion of the assigned task encompassed the modeling aspects of flexible multibodies that can undergo large angular displacements. Research in the area of modeling aspects were also surveyed, with special attention given to the component mode approach. Resulting from this is a research plan on various modeling aspects to be investigated over the next year. The relationship between the large angular displacements, boundary conditions, mode selection, and system modes is of particular interest. The other portion of the assigned task was the generation of a test plan for experimental verification of analytical and/or computer analysis techniques used for flexible multibody systems. Based on current and expected frequency ranges of flexible multibody systems to be used in space applications, an initial test article was selected and designed. A preliminary TREETOPS computer analysis was run to ensure frequency content in the low frequency range, 0.1 to 50 Hz. The initial specifications of experimental measurement and instrumentation components were also generated. Resulting from this effort is the initial multi-phase plan for a Ground Test Facility of Flexible Multibody Systems for Modeling Verification and Control. The plan focusses on the Multibody Modeling and Verification (MMV) Laboratory. General requirements of the Unobtrusive Sensor and Effector (USE) and the Robot Enhancement (RE) laboratories were considered during the laboratory development

Morals From Rationality Alone? Some Doubts

Contractarians aim to derive moral principles from the dictates of instrumental rationality alone. But it is well-known that contractarian moral theories struggle to identify normative principles that are both uniquely rational and morally compelling. Michael Moehler's recent book, *Minimal Morality* seeks to avoid these difficulties by developing a novel "two-level" social contract theory, which restricts the scope of contractarian morality to cases of deep and persistent moral disagreement. Yet Moehler remains ambitious, arguing that a restricted version of Kant's categorical imperative is a uniquely rational principle of conflict resolution. We develop a formal model of Moehler's informal game-theoretic argument, which reconstructs a valid argument for Moehler's conclusion. This model, in turn, enables us to expose how a successful argument for Moehler's contractarian principle rests on assumptions that can only be justified by subtle yet significant departures from the standard conception of rationality. We thus extend our understanding of familiar contractarian difficulties by showing how they arise even if we restrict the scope of contractarian morality to a domain where its application seems both promising and necessary. We show that the problem lies not in contractarians' immodest ambitions but in the modest resources rationality can offer to satisfy them

Modular vector fields attached to Dwork family: sl2(C)\mathfrak{sl}_2(\mathbb{C}) Lie algebra

We introduce an algebraic group $\sf G$ that acts from right on the moduli space $\textsf{T}$ of Calabi-Yau $n$-folds arising from Dwork family enhanced with differential forms, and describe its Lie algebra ${\rm Lie}({\sf G})$. We observe that ${\rm Lie}({\sf G})$ together with a modular vector field ${\sf R}$ on $\textsf{T}$ generates another Lie algebra $\mathfrak{G}$, called AMSY-Lie algebra, such that $\dim \mathfrak{G}=\dim {\sf T}$. We find $\mathfrak{sl}_2(\mathbb{C})$ as a Lie subalgebra of $\mathfrak{G}$ that contains $\sf R$.Comment: 20 page

The influence of tannins on the extrafloral nectar characteristics and insect mutualists of Vicia faba L.

The main objective of this research project was to investigate the influence of tannins on the extrafloral nectar characteristics and insect mutualists of Vicia faba L. Tannin-free cultivars of V. faba have become increasingly popular in Western Canada due to the greater digestibility of their protein by monogastrics; however, the effect of their lack of tannins on mutualistic insects is unknown. Tannin-rich cultivars of V. faba produce characteristic dark spots on the flowers’ wing petals, and on the stipular extrafloral nectaries (EFNs), which are often used by insects to help locate nectaries. Tannin-free V. faba cultivars lack these nectar guides and spots though, and may be unable to attract as many beneficial insects to the EFNs for herbivore-control purposes, and to the flowers for pollination. Accordingly, this study investigated two tannin-rich (Fatima, SSNS-1) and two tannin-free cultivars (Snowbird, Snowdrop). Extrafloral nectar characteristics were also examined, as the production of tannins can be metabolically expensive, and could come at the cost of extrafloral nectar secretion. Tannin-free cultivars are therefore expected to attract fewer beneficial insects due to their unmarked flowers and EFNs, unless the lack of tannins corresponds with an increased production of nectar or nectar sugars. To examine the effects of tannins on the insect mutualists of V. faba, surveys of insect visitors to the EFNs and flowers were conducted throughout the summers of 2013 and 2014. The vast majority of insect visitors to EFNs were ants (Formicidae), followed by ladybird beetles (Coccinellidae), flies of Camptoprosopella borealis Shewell (Lauxaniidae), and predatory (Vespidae) and parasitoid (Ichneumonidae) wasps, whereas the bees Apis mellifera L. and Bombus nevadensis Cresson were the most common visitors to the flowers. The cultivars which those species were present or absent at during surveys were analyzed using generalized mixed models. The results did not support any consistent differences in insect visitors to plants with tannins, compared to those without, suggesting that the marked difference in the visibility of EFNs on tannin-rich cultivars is not essential for EFN recognition by many insect species. Furthermore, insect visits to EFNs occurred at a highly conserved relative location along the stem, due to a probable increase in nectar production a short distance from the shoot apex. For future reference, stipules at this node were termed the Primary Active EFNs. Extrafloral nectar characteristics were studied in a growth chamber through a combination of nectar sampling by microcapillaries and refractometer measurements to examine nectar volume and sugar concentration, respectively, as well as high performance liquid chromatography to measure the proportion of each of the nectar sugars present. On average, the extrafloral nectar per stipule ± S.E.M had a volume of 0.363 ± 0.021 µL, a nectar sugar concentration (by weight) of 32.5 ± 1.3 %, a nectar sugar mass of 137.6 ± 10.0 µg, and a sugar composition of 54.4 ± 1.0% glucose, 31.1 ± 1.0% fructose, and 14.5 ± 1.0% sucrose. Although extrafloral nectar characteristics varied between cultivars, the variability did not appear dependent on tannin presence or absence, nor did it appear to influence the presence or absence of the abundant ant species Formica neoclara Emery, F. podzolica Francoeur, and Lasius pallitarsis (Provancher), at different cultivars in the field. The increased digestibility provided by tannin-free cultivars of V. faba to monogastrics such as chickens, therefore, does not appear to come at the cost of reduced visitation to the plants by ants and other beneficial insects

Effect of phosphorus application on wheat yield and phosphorus uptake in a Brown Chernozem in southern Saskatchewan

Non-Peer Reviewe

Effect of application method on fate of phosphorus fertilizer

Non-Peer Reviewe

Verification of component mode techniques for flexible multibody systems

Investigations were conducted in the modeling aspects of flexible multibodies undergoing large angular displacements. Models were to be generated and analyzed through application of computer simulation packages employing the 'component mode synthesis' techniques. Multibody Modeling, Verification and Control Laboratory (MMVC) plan was implemented, which includes running experimental tests on flexible multibody test articles. From these tests, data was to be collected for later correlation and verification of the theoretical results predicted by the modeling and simulation process

Geochemical Endmembers preserved in Gale Crater: A tale of two mudstones and their compositional differences according to ChemCam

Gale crater contains two fine-grained mudstone sedimentary units: The Sheepbed mudstone member, and the Murray formation mud-stones. These mudstones formed as part of an ancient fluviolacustrine system. The NASA Curiosity rover has analysed these mudstone units using the Chemistry and Camera (ChemCam), Alpha Particle X-ray Spectrometer (APXS) and Chemistry and Mineralogy (CheMin) onboard instrument suites. Subsequent mineralogical analyses have uncovered a wide geochemical and mineralogical diversity across and within these two mudstone formations. This study aims to determine the principal cause (alteration or source region) of this geochemical variation through a statistical analysis of the ChemCam dataset up to sol 1482, including the lower to middle Murray formation

Time Explains Regional Richness Patterns within Clades More Often than Diversification Rates or Area

Most groups of organisms occur in multiple regions and have different numbers of species in different regions. These richness patterns are directly explained by speciation, extinction, and dispersal. Thus, regional richness patterns may be explained by differences in when regions were colonized (more time for speciation in regions colonized earlier), differences in how often they were colonized, or differences in diversification rates (speciation minus extinction) among regions (with diversification rates potentially influenced by area, climate, and/or many other variables). Few studies have tested all three factors, and most that did examined them only in individual clades. Here, we analyze a diverse set of 15 clades of plants and animals to test the causes of regional species richness patterns within clades. We find that time was the sole variable significantly explaining richness patterns in the best-fitting models for most clades (10/15), whereas time combined with other factors explained richness in all others. Time was the most important factor explaining richness in 13 of 15 clades, and it explained 72% of the variance in species richness among regions across all 15 clades (on average). Surprisingly, time was increasingly important in older and larger clades. In contrast, the area of the regions was relatively unimportant for explaining these regional richness patterns. A systematic review yielded 15 other relevant studies, which also overwhelmingly supported time over diversification rates (13 to 1, with one study supporting both diversification rates and time). Overall, our results suggest that colonization time is a major factor explaining regional-scale richness patterns within clades (e.g., families).National Natural Science Foundation of China [31670422, 31770402, 31770443]; Qinlan Project of Nanjing Normal University; Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) of Jiangsu Higher Education Institutions; US National Science Foundation [DEB 1655690]12 month embargo; Published online: 20 February 2019This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]