Revealing the role of the constant phase element in relaxor ferroelectrics

Relaxor ferroelectrics exhibit both static and dynamic local structural order which controls their frequency-dependent electrical properties. A combination of advanced scattering and microscopy techniques have been used recently to determine the local structure of relaxors. To complement these, here we show an approach to electrical property measurements which identifies local dipoles whose switching is co-operative, temperature-dependent and responsible for the observed dispersion in dielectric properties. Impedance measurements and equivalent circuit analysis of a canonical relaxor, Pb(Mg1/3Nb2/3)O3 single crystal, over the ranges 180–1050 K and 100 Hz–1 MHz, show that incorporation of a single constant phase element into the equivalent circuit used to fit experimental data is able to account fully for the dispersions that characterise the relaxor response, over this frequency range. This allows parametrisation of the relaxor behaviour, gives increased understanding of the relaxation mechanisms responsible and forms the basis for modifying and controlling relaxor characteristics.

A nonparametric analysis of competitiveness efficiency: The relevance of firm size and the configuration of competitive pillars

This study employs a data envelopment analysis (DEA) model with a single constant input to analyze the competitiveness performance of a unique sample of 103 knowledge-intensive business service (KIBS) firms from Hungary, Spain, Colombia, and Costa Rica for the year 2017. Also, we assess how the configuration of competitive pillars—strengths and weaknesses—affects efficiency and how firm size moderates this relationship. The mean efficiency scores by which the competitiveness output can be optimized is 47.43%. The results suggest that the configuration of competitive pillars has important implications for efficiency analyses. For small businesses, competitive-enhancing actions should focus on mitigating competitive weaknesses that are detrimental to efficiency. Also, a configuration of competitive pillars in which one or various competitive strengths prevail is more beneficial for small businesses. Managerial tools such as the proposed competitiveness measure may offer useful information on what strategic actions can contribute to optimize business competitiveness. JEL CLASSIFICATION C14; L19; L25

A Novel Delay-Dependent Asymptotic Stability Conditions for Differential and Riemann-Liouville Fractional Differential Neutral Systems with Constant Delays and Nonlinear Perturbation

The novel delay-dependent asymptotic stability of a differential and Riemann-Liouville fractional differential neutral system with constant delays and nonlinear perturbation is studied. We describe the new asymptotic stability criterion in the form of linear matrix inequalities (LMIs), using the application of zero equations, model transformation and other inequalities. Then we show the new delay-dependent asymptotic stability criterion of a differential and Riemann-Liouville fractional differential neutral system with constant delays. Furthermore, we not only present the improved delay-dependent asymptotic stability criterion of a differential and Riemann-Liouville fractional differential neutral system with single constant delay but also the new delay-dependent asymptotic stability criterion of a differential and Riemann-Liouville fractional differential neutral equation with constant delays. Numerical examples are exploited to represent the improvement and capability of results over another research as compared with the least upper bounds of delay and nonlinear perturbation.

Post Construction and Long Term Settlement of an Embankment Dam Computed with Two Constitutive Models

For the settlement computation of an embankment dam, the soil stiffness is of great importance. Unfortunately, due to the lack of funds allocated for geotechnical investigation, stiffness parameters are commonly not evaluated as compared to strength properties. As a result, this may create hindrance in the use of advanced constitutive models such as Hardening Soil Model (HSM). In this study, the settlement with respect to depth and long term settlement of an embankment dam computed with Mohr-Coulomb Model (MCM) is compared with that of HSM applied to foundation soil only with limited data on stiffness. The results show that the MCM overestimated settlement in comparison with HSM. The settlement increment of MCM, in comparison with HSM, at the crest and at the depth of 120m was 53% and 82% respectively after the filling of the reservoir. The settlement computed with MCM and HSM were 2.9% and 1.35% of the dam height. It can be interpreted that the settlement predicted with MCM is unrealistically high due to the single constant value of modulus of elasticity (MOE), while the predictions of HSM are in agreement with the literature. In addition, the long term settlement computed using MCM is about 59% higher than that of HSM for the condition after the filling of the reservoir. This paper shows that the settlement of an embankment dam could be predicted reliably by using HSM even when a limited number of stiffness data is available.

A soft ring oscillator

Periodic actuation of multiple soft, pneumatic actuators requires coordinated function of multiple, separate components. This work demonstrates a soft, pneumatic ring oscillator that induces temporally coordinated periodic motion in soft actuators using a single, constant-pressure source, without hard valves or electronic controls. The fundamental unit of this ring oscillator is a soft, pneumatic inverter (an inverting Schmitt trigger) that switches between its two states (“on” and “off”) using two instabilities in elastomeric structures: buckling of internal tubing and snap-through of a hemispherical membrane. An odd number of these inverters connected in a loop produces the same number of periodically oscillating outputs, resulting from a third, system-level instability; the frequency of oscillation depends on three system parameters that can be adjusted. These oscillatory output pressures enable several applications, including undulating and rolling motions in soft robots, size-based particle separation, pneumatic mechanotherapy, and metering of fluids. The soft ring oscillator eliminates the need for hard valves and electronic controls in these applications.

Building Variable Productivity Ratios for Improving Large Scale Spatially Explicit Pruning Biomass Assessments

Biomass assessments of agro–residues performed at large geographical scales generally base calculations on single constant pruning productivity ratios (RSRs). Reliability of biomass assessments shall be improved if RSRs respond to prevailing regional crop growing conditions. The present paper describes the methodology applied to create geographically varying pruning RSR ratios–tons of dry matter per hectare—for five crop groups: vineyard, olive, fruit species, citrus and dry fruits. A newly created database containing 230 records–from seven EU28 countries—is submitted to statistical analysis. Results reveal that agro-climatic conditions are able to explain a not negligible share of the pruning productivity as dependent variable. Subsequent regression analysis provides two equations—for vineyard and citrus—achieving a reasonable good fitting (R2 0.18 and 0.42 respectively) between RSR and the agroclimatic variables. Analysis of olive, fruit species and dry fruits scatter and whisker plots were useful for zoning and inducing ramp functions. A Geographical Information System (GIS) was utilised to apply the functions to the agroclimatic raster coverages in order to obtain RSR raster grids. Zonal statistic procedures applied by European regional units (NUTs0, NUTs2, NUTs3) provide a specific crop RSR ratio per administrative unit as a principal output of the present work.