Novel non-stoichiometric (Ba0.91Ca0.09)x(Zr0.18Ti0.82)O3 ferroelectric ceramics with improved diffuse phase transition and dielectric tunable performance

Dielectric tunable properties in ferroelectric ceramics have been optimized by a variety of approaches, e.g., isovalent/aliovalent substitution, system composite et al., while the study of non-stoichiometric regulation on the performance of BCZT ceramics was rarely concerned. Herein, a series of novel non-stoichiometric (Ba_0·91Ca_0.09)_x (Zr_0·18Ti_0.82)O₃ (BCZTx) ceramic specimens were successfully prepared via solid-state reaction. The microstructures of BCZTx ceramics are simultaneously investigated through XRD and SEM. The diffuse phase transition (DPT) behaviour of BCZTx ceramics are studied by the Lorentz-type empirical formula. The significant enhancement of DPT behaviour is observed at x = 1.03, which probably due to the coaction of the generation of partial Schottky defects and prominent reduction of grain size. Furthermore, a high tunability (k) 87.80%, low dielectric loss (tan δ) 0.141%, and a remarkably enhanced FOM of 623 are achieved in x = 0.99 at a low DC bias electric fields (BEFs) of 7.28 kV/cm and room temperature (RT), which is superior to that of the stoichiometric BCZT ceramics and other available reported BT-based ceramics systems in term of the dielectric tunable properties. Meanwhile, it shows that the temperature dependent CQF value of x = 0.99 remained advantageous around the RT. These findings suggested that non-stoichiometric BCZTx ceramics with x = 0.99 are significantly competitive in the applications of dielectric tunable devices at RT. The non-stoichiometric regulation is an effective approach in improving the dielectric tunability properties of BCZT ceramics.     

Patterns in environmental priorities revealed through government open data portals

The ways in which environmental priorities are framed are varied and influenced by political forces. One technological advance--the proliferation of government open data portals (ODPs)--has the potential to improve governance through facilitating access to data. Yet it is also known that the data hosted on ODPs may simply reflect the goals and interests of multiple levels of political power. In this article, I use traditional statistical correlation and regression techniques along with newer natural language processing and machine learning algorithms to analyze the corpus of datasets hosted on government ODPs (total: 49,066) to extract patterns that relate scales of governance and political liberalism/conservatism to the priorities and meaning attached to environmental issues. I find that state-level and municipal-level ODPs host different categories of environmental datasets, with municipal-level ODPs generally hosting more datasets pertaining to services and amenities and state-level ODPs hosting more datasets pertaining to resource protection and extraction. Stronger trends were observed for the influences of political conservatism/liberalism among state-level ODPs than for municipal-level ODPs.     

High-rate capability of carbon-coated micron-sized hexagonal TT-Nb2O5 composites for lithium-ion battery

With excellent specific capacity, superior cycle stability, safety and strong practical, Nb₂O₅ has been considered as one of the prospective anode materials for lithium-ion batteries (LIBs). However, current study suggests that Nb₂O₅ electrode materials for LIBs still face the vital issues of low electrical conductivity and poor rate performance. Therefore, carbon-coated TT-Nb₂O₅ materials are designed and synthesized through solid state method in this work, which present high specific capacity (228 mA h g^?1 at 0.2C), satisfactory rate properties (107 mA h g^?1 at 20 C). The outstanding electrochemical property can not only give the credit to the pseudocapacitance effect of TT-Nb₂O₅, but also attribute to introduction of carbon. The homogeneous carbon-coated materials enhance the electrical conductivity, increase the electron transmission speed and alleviate particle crushing. This research not only offers a new method for preparing excellent electrode materials, but also provides a kind of excellent anode material with prospective application for LIBs.     

Adaptive finite-time tracking control for parameterized nonlinear systems with full state constraints

In this article, the issue of adaptive finite-time dynamic surface control (DSC) is discussed for a class of parameterized nonlinear systems with full state constraints. Using the property of logarithmic function, a one-to-one nonlinear mapping is constructed to transform a constrained system into an unconstrained system with the same structure. The nonlinear filter is constructed to replace the first-order linear filter in the traditional DSC, and the demand on the filter time constant is reduced. Based on finite-time stable theory and using modified DSC, the finite-time controller is designed via DSC. Theoretical analysis shows that all the signals in the closed-loop system are semiglobal practical finite-time stable. Furthermore, none of the states are outside the defined open set. In the end, simulation results are presented to demonstrate the effectiveness of the proposed control schemes with both linear filters and nonlinear filters.     

The effect of stocking density and a blind on the behavior of Holstein dairy cows in group maternity pens. Part II: Labor length,lying behavior,and social behavior

In natural settings, dairy cows separate from the herd to give birth. When kept indoors, seeking isolation before calving may be restricted and may depend on space and resources provided in maternity housing. The effect of group maternity pens on behavior around calving and labor progress is unknown. Therefore, the objective of this study was to determine the effects of stocking density and provision of a blind in group bedded pack maternity pens on lying and social behavior as well as length of labor of preparturient dairy animals. The study was conducted as a complete randomized block design with a 2 × 2 factorial arrangement of treatments including stocking density and presence or absence of a blind, resulting in a total of 4 treatments: (1) high stocking density (7.7–12.9 m² lying space/cow) with a blind, (2) low stocking density (15.4–25.8 m²) with a blind, (3) high stocking density without a blind, and (4) low stocking density without a blind. A total of 127 primiparous heifers and 247 multiparous cows were housed in mixed-parity groups from approximately 3 wk before and immediately after calving. During the 4 h before calving, lying behavior (lying time and bouts) was collected automatically using accelerometers, and social behavior (agonistic interactions, allogrooming, and attention from other cows), stage II labor duration, and frequency of position change during stage II labor were collected using video. Lying behavior was collected with accelerometers. Regardless of treatment, lying time and bouts increased as calving approached. Cows and heifers performed more lying bouts in low stocking density pens compared with high stocking density pens. Agonistic interactions and allogrooming were not different between treatments. Other cows spent more time paying attention to focal animals regardless of stocking density as calving approached, but time spent paying attention was reduced by the presence of a blind during h ?2 before calving. The hazard of calving unassisted was greater for cows and heifers in low stocking density pens with a blind compared with all other treatments. Further, animals in pens with a blind tended to change positions fewer times during stage II labor. These results suggest that providing a blind in group maternity pens may improve the calving environment for cows and heifers and, in combination with low stocking density, may reduce the amount of time spent in labor.     

Extended-state-observer-based dynamic surface control of flexible-joint robot systems with input saturation

This article presents an extended-state-observer-based dynamic surface control approach for flexible-joint robot systems with asymmetric input saturation and large unknown dynamic knowledge. Traditional controllers for flexible-joint robot systems usually use approximation technology to deal with unknown dynamics knowledge. Unlike the traditional control algorithm, this article utilizes an extended state observer to estimate the unknown dynamics. For the closed-loop system, the delay strategy handles the time-scale separation issue, the filtering system overcomes the “explosion of differentiation” caused by the repeated differentiation of auxiliary control signals, and the mean-value-theorem solves the input saturation problem of the actuator. The stability analysis implies that estimation errors of extended state observers (ESOs) and other state variables are semiglobally uniformly ultimately bounded. Compared with fuzzy control algorithms, the novel ESO-based dynamic surface control approach not only omits online learning time but also uses only a few control parameters to obtain satisfactory tracking performance. Finally, a comparison simulation experiment is provided to illustrate the effectiveness of the gained conclusions.     

Patterns and stability of food preferences among a national representative sample of young,middle-aged,and elderly adults in China: A latent transition analysis

The purpose of this study was to explore the patterns and stability of, as well as the predictors for, Chinese adults’ food preferences. With the panel data set derived from the China Health and Nutrition Survey (CHNS), latent class analysis (LCA) and latent transition analysis (LTA) were employed to analyze the data of 8850 adults aged 18–40 years (young), 41–60 years (middle-aged) and 61 years above (elderly) over a 4-year period (year 2011 as baseline and year 2015 as follow-up). Latent class analysis revealed three types of food preferences: preference for fruits and vegetables, preference for a varied diet and low food preference. Gender, dietary knowledge, residence, education, and BMI were revealed as significant predictors of the class memberships. From baseline to follow-up, the most stable status in young adult group was preference for fruits and vegetables as it had a high transition probability 0.764 of remaining in the same class. While low food preference and preference for a varied diet statuses were unstable, they had transition probabilities of 0.590 and 0.554, respectively, moving to the preference for fruits and vegetables in year 2015. For middle-aged and elderly groups, the most stable and unstable statuses were preference for fruits and vegetables and preference for a varied diet, respectively. The unstable classes all had over 50% probability of moving to the preference for fruits and vegetables after four years. Potential explanations and implications are also discussed.     

pH-sensitive self-assembling property of poly(ethyleneimine)/cinnamic acid mixture and its effect on pH-dependent release of monoolein cubic phase

Poly(ethyleneimine) (PEI)/cinnamic acid (CA) mixture was self-assembled into microsphere in aqueous phase. As the pH value increased, the self-assembly became hardly formed. As the molar ratio of the amino group of PEI to the carboxyl group of CA increased, the pH window for the formation of self-assembly became broader. The phase transition temperature of cubic phase was 58.5–67.5°C, depending on the PEI/CA content. The release of dye loaded in cubic phase containing PEI/CA increased in a first-order fashion. The release degree was higher at a lower pH value.     

On monitoring the process mean of autocorrelated observations with measurement errors using the w-of-w runs-rules scheme

Runs-rules have been widely used since the 1950s in industrial and nonindustrial process monitoring applications to improve the performance of basic and other traditional monitoring schemes. However, none of the studies on runs-rules have accounted for a process with a combined effect of measurement errors and autocorrelation. Hence, in this paper, the use of the w-of-w runs-rules to improve the performance of the Shewhart $\overline{X}$ scheme using an additive model with a constant variance and a first-order autoregressive model is proposed. To reduce the combined negative effect of measurement errors and autocorrelation, we implement a sampling strategy based on rational subgroups in which (a) multiple measurements per item are taken (instead of a standard single measurement) and (b) non-neighboring observations are gathered. Moreover, the latter sampling strategy is incorporated into the values of probability elements of a Markov chain matrix which is used to derive some closed-form expressions for the zero- and steady-state run-length distribution. The main finding of this study is that, with respect to some overall performance measures, the proposed scheme outperforms the existing Shewhart $\overline{X}$ scheme by a significant margin. A real-life example is used to illustrate the practical implementation of the proposed scheme.