Multiaxial fatigue assessment for outer cylinder of landing gear by critical plane method

The in-service loadings on the landing gear are usually complex and from different directions, which lead to the fatigue critical locations in the landing gear structure mostly in multiaxial stress state. A methodology based on the critical plane method was proposed for estimating the fatigue lifetime of outer cylinder of the main landing gear undergoing variable amplitude (VA) multiaxial proportional loading. The orientation of the critical plane was determined by the so-called maximum variance method. The Bannantine–Socie’s cycle counting method and Miner’s linear rule were applied with Zhang–Yao’s criterion in this research. The calculated results on the fatigue lifetime of the outer cylinder were compared with the experimental data. The results indicate that the methodology proposed in this article is a sound method for fatigue life prediction of engineering components bearing complex VA multiaxial fatigue loading.

Strategy to strengthen the traditional milpa family production systems

Objective: To characterize family production units (FPUs) to identify critical points for their activities and propose intervention strategies for them.Design/methodology/approach: The research took place at Yaxcabá municipality, state of Yucatán, Mexico. It is descriptive and its information obtained through 1) a questionnaire in a mobile application compatible with the Android operating system, structured by modules: producer data, FPU characteristics, crops, infrastructure, machinery, equipment, and marketing. The sample size was randomized with replacement, under the maximum variance condition, 2) assessment visits to the farmer’s plots and 3) participatory community diagnosis workshops.Results: The traditional milpa system was oriented to the cultivation of corn, beans and squash of creole origin, for consumption by the FPUs with minimum technologies usage. Through apiculture, producers obtain an economic resource to finance other activities, including those of the milpa. It is, therefore, necessary to strengthen their productivecapacities of this activity with a chain approach, for the diversification of their products and derivatives of their hives that allow their income to increase.Limitations on study/implications: The proposals and intervention strategies may only be applied to the production system in the evaluated area.Findings/conclusions: The strategies for the traditional milpa production should be oriented to food security, biodiversity preservation and the nutritional health of their related population. Apuculture strategies should aim to include producers in the value chain.

Microrheology With an Anisotropic Optical Trap

Microrheology with optical tweezers (MOT) measurements are usually performed using optical traps that are close to isotropic across the plane being imaged, but little is known about what happens when this is not the case. In this work, we investigate the effect of anisotropic optical traps on microrheology measurements. This is an interesting problem from a fundamental physics perspective, but it also has practical ramifications because in 3D all optical traps are anisotropic due to the difference in the intensity distribution of the trapping laser along axes parallel and perpendicular to the direction of beam propagation. We find that attempting viscosity measurements with highly anisotropic optical traps will return spurious results, unless the axis with maximum variance in bead position is identified. However, for anisotropic traps with two axes of symmetry such as traps with an elliptical cross section, the analytical approach introduced in this work allows us to explore a wider range of time scales than those accessible with symmetric traps. We have also identified a threshold level of anisotropy in optical trap strength of ~30%, below which conventional methods using a single arbitrary axis can still be used to extract valuable microrheological results. We envisage that the outcomes of this study will have important practical ramifications on how all MOT measurements should be conducted and analyzed in future applications.

Spatiotemporal structure of Baltic free sea level oscillations in barotropic and baroclinic conditions from hydrodynamic modelling

Free sea level oscillations in barotropic and baroclinic conditions were examined using numerical experiments based on a 3-D hydrodynamic model of the Baltic Sea. In a barotropic environment, the highest amplitudes of free sea level oscillations are observed in the northern Gulf of Bothnia, eastern Gulf of Finland, and south-western Baltic Sea. In these areas, the maximum variance appears within the frequency range corresponding to periods of 13–44 h. In a stratified environment, after the cessation of meteorological forcing, water masses relax to the equilibrium state in the form of mesoscale oscillations at the same frequencies as well as in the form of rapidly decaying low-frequency (seasonal) oscillations. The total amplitudes of free baroclinic perturbations are significantly larger than those of barotropic perturbations, reaching 15–17 cm. Contrary to barotropic, oscillations in baroclinic conditions are strongly pronounced in the deep-water areas of the Baltic Sea proper. Specific spatial patterns of amplitudes and phases of free barotropic and baroclinic sea level oscillations identified them as progressive–standing waves representing barotropic or baroclinic modes of gravity waves and topographic Rossby waves.

Depression and Religiosity as Correlates of Quality of Life in Senior Citizens

The present study explored the relationship between depression, religiosity and quality of life in senior citizens. The sample comprised of 400 senior citizens (above 60 years) with equal number of educated males and females (200 each). The analysis revealed that in females’ sample, depression explained the maximum variance of 21% followed by religiosity explained 4% in quality of life. In all, these variables have accounted for 25% of total variance whereas; in males’ sample only depression emerged in a significant predictor that explained 8% of variance. Further, t test has revealed the superiority of males in quality of life and female’s superiority on depression, and religiosity.

Vulnerability of Northern Adriatic to Warming and Intensification of Marine Heat Waves

<p>Northern Adriatic Shelf (NAS) is a shallow, semi-enclosed northern part of the Adriatic basin, and as such rapidly responds to climate change. Multidecadal satellite and in-situ sea surface temperature (SST) time series on the NAS indicate a warming trend. During 1995-2015, SST in the Gulf of Trieste increased at a rate of 0.08°C ± 0.01°C per year (amounting to 1.6°C in 20 years), a trend indicative of the entire NAS shelf.</p><p>We use a centennial SST time series from Trieste (Raicich and Colucci, 2019) to construct a climatological year as a base for SST day-of-year anomaly estimation. We show that yearly number of discrete periods of extreme warming (Marine Heat Waves - MHW) and extreme cooling (Marine Cold Spells - MCS) exhibit clear seasonality. Both positive and negative anomalies from climatological SST manifest maximum variance in the summer months. The frequency of MHW has increased, while the number of Marine Cold Spells (MCS) is declining.</p><p>Sea warming and MHW intensification are potent agents of disturbance, particularly for sessile taxa and species residing near their warm range edges. In the NAS extreme events may force regression of habitat-forming species such as seagrass Zostera marina and increase bleaching episodes of coral Cladocora caespitosa. Warming events may be associated with the inflow of invasive non-indigenous species and expand the period of occurrence, such as harmful gelatinous invader Mnemiopsis leidyi. In contrast, a reduced number of MCS during winter may enhance survival of Aurelia polyps generating through strobilation more intense jellyfish blooms.</p>