Finite Element Modeling of Small-Scale Tapered Wood-Laminated Composite Poles with Biomimicry Features1

Tapered composite poles with biomimicry features as in bamboo are a new generation of wood laminated composite poles that may some day be considered as an alternative to solid wood poles that are widely used in the transmission and telecommunication fields. Five finite element models were developed with ANSYS to predict and assess the performance of five types of composites members: a tapered hollow pole with webs (Pole-A), a tapered hollow pole without webs (Pole-B), a tapered solid composite pole (Pole-C), a uniform-diameter hollow pole with webs (Pole-D), and a uniform-diameter hollow pole without webs (Pole-E). The predicted deflection by these models agreed well with those of the experiment, and the predicted normal stress agreed with those calculated. The normal and shear stress distributions inside the members were investigated, and stress distributions in the XY and YZ planes are exhibited. As expected, the webs reduced the local shear stress and improved shear capacity, especially in the top and groundline regions where shear levels were the highest. The webs had little effect on the normal stress. Shear stress increased from the bottom to the top for the members with taper. Large shear stress concentration was predicted in a small region close to the groundlines. The models also predicted that the shear stress of the tapered hollow poles would decrease from the inside to the outside surfaces in XY plane

Cosmological Scaling Solutions of Multiple Tachyon Fields with Inverse Square Potentials

We investigate cosmological dynamics of multiple tachyon fields with inverse square potentials. A phase-space analysis of the spatially flat FRW models shows that there exists power-law cosmological scaling solutions. We study the stability of the solutions and find that the potential-kinetic-scaling solution is a global attractor. However, in the presence of a barotropic fluid the solution is an attractor only in one region of the parameter space and the tracking solution is an attractor in the other region. We briefly discuss the physical consequences of these results.Comment: 10 pages, 1 figure, LaTeX2

The Primordial Perturbation Spectrum from Various Expanding and Contracting Phases

In this paper, focusing on the case of single scalar field, we discuss various expanding and contracting phases generating primordial perturbations, and study the relation between the primordial perturbation spectrum from these phases and the parameter w of state equation in details. Furthermore, we offer an interesting classification for the primordial perturbation spectrum from various phases, which may have important implications for building an early universe scenario embedded in possible high energy theories.Comment: 5 pages, 3 eps figure

Bayesian dissection for genetic architecture of traits associated with nitrogen utilization efficiency in rice

Nitrogen is one of the key important nutrients in rice production. High rice grain yield is greatly dependent upon economic nitrogen input and genetic factors. In order to locate quantitative loci for traits associated with nitrogen utilization efficiency in rice, F9 recombinant inbred lines derived from a Korean tongil type Dasanbyeo and a Chinese japonica variety TR22183 was genetically designed. The six traits of interest were observed on 155 RILs, along with 105 SSR and 103 STS markers. Bayesian model selection technique was used to dissect genetic architecture for traits of interest. A total of 28 main-effect QTLs and 23 pairs of epistatic QTLs were detected for traits associated with nitrogen utilization efficiency. The proportions of phenotypic variation explained by the detected QTLs ranged from 0.09 to 16.90% and from 0.19 to 12.76% for main-effect and epistatic QTLs, respectively. Sixteen of main-effect QTLs interacted with nitrogen level. One pleiotropic QTL was found, governing simultaneously nitrogen dry matter production efficiency and Nitrogen grain production efficiency

F-term, D-term and hybrid brane inflation

We study inflation and reheating in models for the brane universe, considering hybrid brane inflation without tachyon condensation. We expect that some fields that are localized on different branes interact with O(1) coupling when branes are on top of each other, while the interaction vanishes when branes are separated at a distance. If the interaction is needed to avoid spontaneous breaking of supersymmetry on the brane, our idea for hybrid brane inflation works. In our model, when branes are far apart, supersymmetry is spontaneously broken by the fields on a brane, which induces inflation. The inflaton field is the moduli for the brane distance. At the end of inflation, when branes come close, supersymmetry is restored by the interaction between fields on the branes, then the oscillation starts to reheat the Universe. In this paper we construct explicit models for F-term and D-term inflation. There are at least two major advantages. The most attractive point is that reheating is natural in our model, because the trigger field is not the tachyon but a conventional field on the brane. The serious constraint from the loop correction, which always appears in conventional models for hybrid inflation, is avoided.Comment: 13pages, latex2e, final version, to appear in JCA

Inflationary attractor in Gauss-Bonnet brane cosmology

The inflationary attractor properties of the canonical scalar field and Born-Infeld field are investigated in the Randall-Sundrum II scenario with a Gauss-Bonnet term in the bulk action. We find that the inflationary attractor property will always hold for both the canonical and Born-Infeld fields for any allowed non-negative Gauss-Bonnet coupling. We also briefly discuss the possibility of explaining the suppressed lower multiples and running scalar spectral index simultaneously in the scenario of Gauss-Bonnet brane inflation.Comment: 7 pages, no figures. An error in the discussion of BI field corrected, conclusion correcte

Second-Order Time-Dependent Mild-Slope Equation for Wave Transformation

This study is to propose a wave model with both wave dispersivity and nonlinearity for the wave field without water depth restriction. A narrow-banded sea state centred around a certain dominant wave frequency is considered for applications in coastal engineering. A system of fully nonlinear governing equations is first derived by depth integration of the incompressible Navier-Stokes equation in conservative form. A set of second-order nonlinear time-dependent mild-slope equations is then developed by a perturbation scheme. The present nonlinear equations can be simplified to the linear time-dependent mild-slope equation, nonlinear long wave equation, and traditional Boussinesq wave equation, respectively. A finite volume method with the fourth-order Adams-Moulton predictor-corrector numerical scheme is adopted to directly compute the wave transformation. The validity of the present model is demonstrated by the simulation of the Stokes wave, cnoidal wave, and solitary wave on uniform depth, nonlinear wave shoaling on a sloping beach, and wave propagation over an elliptic shoal. The nearshore wave transformation across the surf zone is simulated for 1D wave on a uniform slope and on a composite bar profile and 2D wave field around a jetty. These computed wave height distributions show very good agreement with the experimental results available

Was the extreme Northern Hemisphere greening in 2015 predictable?

The year 2015 was, at the time, the warmest since 1880, and many regions in the Northern Hemisphere (NH) registered record breaking annual temperatures. Simultaneously, a remarkable and widespread growing season greening was observed over most of the NH in the record from the Moderate Resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index (NDVI). While the response of vegetation to climate change (i.e. the long term trend) is assumed to be predictable, it is still unclear whether it is also possible to predict the interannual variability in vegetation activity. Here, we evaluate whether the unprecedented magnitude and extent of the greening observed in 2015 corresponds to an expected response to the 2015 climate anomaly, or to a change in the sensitivity of NH vegetation to climate. We decompose NDVI into the long-term and interannual variability components, and find that the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO) explain about half of NDVI interannual variability. This response is in addition to the long-term temperature and human-induced greening trend. We use a simple statistical approach to predict the NDVI anomaly in 2015, using the PDO and AMO states as predictors for interannual variability, and temperature and precipitation trends for the long-term component. We show that the 2015 anomaly can be predicted as an expected vegetation response to temperature and water-availability associated with the very strong state of the PDO in 2015. The link found between climate variability patterns and vegetation activity should contribute to increase the predictability of carbon-cycle processes at interannual time-scales, which may be relevant, for instance, for optimizing land-management strategies

Non-linear Realizations of Conformal Symmetry and Effective Field Theory for the Pseudo-Conformal Universe

The pseudo-conformal scenario is an alternative to inflation in which the early universe is described by an approximate conformal field theory on flat, Minkowski space. Some fields acquire a time-dependent expectation value, which breaks the flat space so(4,2) conformal algebra to its so(4,1) de Sitter subalgebra. As a result, weight-0 fields acquire a scale invariant spectrum of perturbations. The scenario is very general, and its essential features are determined by the symmetry breaking pattern, irrespective of the details of the underlying microphysics. In this paper, we apply the well-known coset technique to derive the most general effective lagrangian describing the Goldstone field and matter fields, consistent with the assumed symmetries. The resulting action captures the low energy dynamics of any pseudo-conformal realization, including the U(1)-invariant quartic model and the Galilean Genesis scenario. We also derive this lagrangian using an alternative method of curvature invariants, consisting of writing down geometric scalars in terms of the conformal mode. Using this general effective action, we compute the two-point function for the Goldstone and a fiducial weight-0 field, as well as some sample three-point functions involving these fields.Comment: 49 pages. v2: minor corrections, added references. v3: minor edits, version appearing in JCA

Scale Invariance from Modified Dispersion Relations

In this paper, inspired by the investigations on the theory of cosmological perturbations in Ho\v{r}ava-Liftshit cosmology, we calculated the spectrum of primordial perturbation leaded by a scalar field with modified dispersion relation \omega\sim k^z/a^{p-1}, in which z is the critical exponent and p is generally not equal to z. We discussed that for fixed z, if the spectrum is required to be scale invariant, how should p depend on the background evolution. We concluded that there is always a room of parameters for the generation of scale invariant spectrum.Comment: 8 pages, 2 figure