A Comparison of Different Modeling Strategies for Predicting Effective Properties of 3D Woven Composites

Three-dimensional (3D) woven composites are an attractive means of achieving superior mechanical performance in aerospace structures. Limited analysis capability currently exists to predict both effective elastic and strength properties for these complex composites. In this study, a comparison of three modeling strategies was performed to assess the ability of the different methods to predict the effective elastic properties of four distinct 3D orthogonal woven composites. Two finite element techniques (in-plane and triply-periodic boundary conditions) and one method of cells technique, the Multiscale Generalized Method of Cells, were considered

Computationally-efficient Structural Models for Analysis of Woven Composites

The paper presents a novel approach to model woven composite using the computationally efficient one-dimensional models. The framework is built within the scheme of the Carrera Unified Formulation (CUF), a generalized hierarchical formulation that generates variable kinematic structural theories. Various components of the woven composite unit cell are modeled using a combination of straight and curved one-dimensional CUF models. By employing a component-wise approach, a modeling technique within CUF, the complex geometry of the woven composite components is modeled precisely. The ability of CUF models to accurately resolve stress and strain fields are exploited to capture complex deformation within a woven composite unit cell. Numerical results include analyses of a non-crimped textile composite, a curved tow under tension, and a dry woven textile unit cell

Translating aboveground cosmic-ray neutron intensity to high-frequency soil moisture profiles at sub-kilometer scale

Above-ground cosmic-ray neutron measurements provide an opportunity to infer soil moisture at the subkilometer scale. Initial efforts to assimilate those measurements have shown promise. This study expands such analysis by investigating (1) how the information from aboveground cosmic-ray neutrons can constrain the soil moisture at distinct depths simulated by a land surface model, and (2) how changes in data availability (in terms of retrieval frequency) impact the dynamics of simulated soil moisture profiles. We employ ensemble data assimilation techniques in a “nearly-identical twin” experiment applied at semi-arid shrubland, rainfed agricultural field, and mixed forest biomes in the USA. The performance of the Noah land surface model is compared with and without assimilation of observations at hourly intervals, as well as every 2 days. Synthetic observations of aboveground cosmic-ray neutrons better constrain the soil moisture simulated by Noah in root-zone soil layers (0–100 cm), despite the limited measurement depth of the sensor (estimated to be 12–20 cm). The ability of Noah to reproduce a “true” soil moisture profile is remarkably good, regardless of the frequency of observations at the semi-arid site. However, soil moisture profiles are better constrained when assimilating synthetic cosmic-ray neutron observations hourly rather than every 2 days at the cropland and mixed forest sites. This indicates potential benefits for hydrometeorological modeling when soil moisture measurements are available at a relatively high frequency. Moreover, differences in summertime meteorological forcing between the semi-arid site and the other two sites may indicate a possible controlling factor to soil moisture dynamics in addition to differences in soil and vegetation properties

Translating aboveground cosmic-ray neutron intensity to high-frequency soil moisture profiles at sub-kilometer scale

Above-ground cosmic-ray neutron measurements provide an opportunity to infer soil moisture at the subkilometer scale. Initial efforts to assimilate those measurements have shown promise. This study expands such analysis by investigating (1) how the information from aboveground cosmic-ray neutrons can constrain the soil moisture at distinct depths simulated by a land surface model, and (2) how changes in data availability (in terms of retrieval frequency) impact the dynamics of simulated soil moisture profiles. We employ ensemble data assimilation techniques in a “nearly-identical twin” experiment applied at semi-arid shrubland, rainfed agricultural field, and mixed forest biomes in the USA. The performance of the Noah land surface model is compared with and without assimilation of observations at hourly intervals, as well as every 2 days. Synthetic observations of aboveground cosmic-ray neutrons better constrain the soil moisture simulated by Noah in root-zone soil layers (0–100 cm), despite the limited measurement depth of the sensor (estimated to be 12–20 cm). The ability of Noah to reproduce a “true” soil moisture profile is remarkably good, regardless of the frequency of observations at the semi-arid site. However, soil moisture profiles are better constrained when assimilating synthetic cosmic-ray neutron observations hourly rather than every 2 days at the cropland and mixed forest sites. This indicates potential benefits for hydrometeorological modeling when soil moisture measurements are available at a relatively high frequency. Moreover, differences in summertime meteorological forcing between the semi-arid site and the other two sites may indicate a possible controlling factor to soil moisture dynamics in addition to differences in soil and vegetation properties

Energy and spectral enhancement of femtosecond supercontinuum in a noble gas using a weak seed

We experimentally demonstrate that the use of a weak seed pulse of energy less than 0.4% of the pump results in a spectral energy enhancement that spans over 2 octaves and a total energy enhancement of more than 3 times for supercontinua generated by millijoule level femtosecond pulses in Krypton gas. Strong four-wave mixing of the pump-seed pulse interacting in the gas is observed. The spectral irradiance generated from the seeding process is sufficiently high to use white-light continuum as an alternative to conventional tunable sources of radiation for applications such as nonlinear optical spectroscopy

Chromosomal copy number variation, selection and uneven rates of recombination reveal cryptic genome diversity linked to pathogenicity

This project was funded by the UK Natural Environmental Research Council (NERC) grant NE/E006701/1, the European Research Council (ERC) grant 260801-BIG_IDEA, the Swiss National Science Foundation grant 31-125099 and the Biodiversa project RACE: Risk Assessment of Chytridiomycosis to European Amphibian Biodiversity (http://www.bd-maps.eu). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

Sex‐biased disease dynamics increase extinction risk by impairing population recovery

The periodicity of life‐cycle events (phenology) modulates host availability to pathogens in a repeatable pattern. The effects of sexual differences in host phenology have been little explored in wildlife epidemiological studies. A recent series of ranavirosis outbreaks led to serious declines of Boscas’ newt populations at Serra da Estrela (Portugal). The peculiar phenology of this species, in which a large number of females remain in the aquatic habitat after the breeding season, turns it into a suitable model to test how sex‐biased mortality can affect host population persistence in the context of infectious diseases. We investigated how the phenology of Bosca's newt (i.e. biased number of females) mediated the impact of Ranavirus. We then evaluated the risk of extinction of the population under different scenarios of sex‐biased mortality using a population viability analysis. Two newt populations (one subject to yearly outbreaks and a comparative site where outbreaks have not been recorded) were tracked for trends over time following emergence of ranaviral disease, allowing us to assess the differential impact of the disease on both sexes. In addition to a significant decline in abundance of adult newts, our data suggest that phenology can affect disease dynamics indirectly, leading to reduction in females and a reversal of the sex ratio of the breeding population. Our models suggest that female‐biased mortality does not exacerbate Ranavirus‐driven population declines in the short‐term, but is likely to have a deleterious impact during the recovery process once the lethal effect of disease is removed from the system

Order-Reduced Solution of the Nonlinear High-Fidelity Generalized Method of Cells Micromechanics Relations

The High-Fidelity Generalized Method of Cells (HFGMC) is one technique for accurately simulating nonlinear composite material behavior. The HFGMC uses a higher-order approximation for the subcell displacement field that allows for a more accurate determination of the subcell stressstrain fields at the cost of some computational efficiency. In order to reduce computational costs associated with the solution of the ensuing system of simultaneous equations, the HFGMC global system of equations for doubly-periodic repeating unit cells with nonlinear constituents was reduced in size through the use of a Petrov-Galerkin-based Proper Orthogonal Decomposition order-reduction scheme. A number of cases were presented that address the computational feasibility of using order-reduction techniques to solve solid mechanics problems involving complex microstructures