Effects of Ta2O5 on the microstructure and electrical properties of ZnO linear resistance ceramics

ZnO-Al2O3-MgO-TiO2-SiO2-Ta2O5 (ZnO-based) linear resistance ceramics with doping different molar percentages of Ta2O5 were prepared by a conventional ceramics method. Effects of Ta2O5 additives on the phase composition, microstructures, and electrical properties of ZnO-based linear resistive ceramics were investigated. The results show that doping Ta2O5 can refine the grains of the main crystalline phase ZnO and the secondary crystalline phase ZnAl2O4 in terms of microstructure, and also can reduce the grain boundary barrier and optimize the I-V characteristics in terms of electrical properties. In addition, the doping of Ta2O5 can improve the stability of the resistivity , and the impedance frequency indicates that the doping of Ta2O5 makes the sample suitable for high-frequency electric fields. The resistivity of the sample doped with 0.2 mol% Ta2O5 is 56.2 Ω·cm, and this sample has the best grain boundary barrier height, nonlinear coefficient and temperature coefficient of resistance of 0.054 eV, 1.04 and -3.48×10-3 / ℃，respectively.

Understanding the Method Effects of the Ethnic Identity Scale Items

This study used the Correlated Traits-Correlated Method (CTCM) model to identify the method effects of the Ethnic Identity Scale (EIS) items, both in favorable and unfavorable items. The study involved 4 alternative models of the CTCM to test the suitability of the model. 440 secondary-school students were involved in this study. Confirmatory Factor Analysis was used employing R software Version 4.0.2. Results indicated alignments between the data with three CTCM alternative models that provided evidence to understand the effect of the method on the use of positive and negative items that could affect the validity of a measuring instrument.

Superconductivity of BSCCO Compound Substituted Partially by Zr Nanoparticles at Bi Site

High-temperature superconductors with a nominal composition Bi2- xZrxPb0.4Sr2Ca2Cu3Oy for (0≤x≤0.3) were prepared by solid-state reaction method. Effects of the Zr nanoparticles substitution at Bi sites have been studied to obtain the optimum concentration for the formation and stabilization of the superconducting samples. Electrical resistivity measurements of the samples showed that the higher critical temperature TC was found at 118 K, which is for the composition Bi1.95Zr0.05Pb0.4Sr2Ca2Cu3Oy. Semiconductor behavior noticed for samples with concentration higher than 0.2. The X-ray diffraction results for all superconducting samples showed an orthorhombic structure with two phases, 2223 high-TC phase and 2212 low-TC phase. The scanning electron microscope has been used to identify the morphology of the superconducting phase. The plate-like grains of the high Bi-2223 phase appeared in most samples besides changes in morphology of the samples with increasing dopant concentration

The Incremental Validity of Average States: A Replication and Extension of Finnigan and Vazire (2018)

States refer to our momentary thoughts, feelings, and behaviors. Average states (aggregates across multiple time points) are discussed as a more accurate and objective measure of personality compared to global self-reports since they do not only rely on people’s general beliefs about themselves. Specifically, Finnigan and Vazire (2018) argued that, if average states better capture what a person is actually like, this should be reflected in their unique association with informant-reports of personality, and tested this idea based on two experience-sampling studies. Their results showed, however, that average self-reported states did not predict global informant-reported personality above and beyond global self-reports. In this research, we aimed at replicating and extending these results. We used data of five studies (total N = 806) that involved global self- and informant-reports and employed a variety of different experience-sampling methods (time-based with different sampling schedules, event-based). Across all studies, the original results (i.e., no incremental effects of average self-reported states) were replicated. Furthermore, as an extension to the original study, we found that average other-reported states (provided by peers, results based on one study) did indeed predict global informant-reports above and beyond global self-reports. These findings highlight the importance of differentiating between method effects (global reports vs. average states) from source of information effects (self vs. other). We discuss these results, focusing on the suitability of using informant-reports as a criterion variable and conceptual differences between assessment methods.

Thermal Simulation and Analysis of the Single LED Module

Light Emitting Diodes (LED) shows an important role in replacing traditional lamps due to their longevity, high efficiency, and environment-friendly operation. However, a large portion of the electricity applied on LED converts to heat, raising up the p-n junction working temperature, and lowering the output-light quality and the LED lifetime as well. Therefore, thermal management for LED is one of the key issues in LEDs lighting application. In order to investigate the impact of each component of the LED module on the junction temperature of the LED, we have performed thermal simulations of a typical single LED module by using the finite element method. Effects of thermal conductivity and thickness of each module’s components on junction temperature were analyzed systematically. The results provided a detailed understanding of thermal behavior of a single LED module and established a crucial insight into thermal management design for high-power white LED lamp. Thermal-interface-materials (TIM) and the dielectric layer are proposed to have thermal conductivity around 1 W/mK for system optimization. In addition, based on the thermal analysis of heat sink, we have proposed and investigated a new configuration of plastic heat sink embedded with aluminum-alloy. The thickness ratio between the embedded aluminum layer and the heatsink base is suggested to be around 0.1 to 0.15 for the optimal configuration.

Effects of Brace Stiffness and Nonlinearity of Viscous Dampers on Seismic Performance of Structures

In the applications of supplemental dampers for seismic hazard mitigation, the supporting braces for the dampers are considered an important component for ensuring an efficient energy dissipation in the structure. Despite their importance, studies on the effects of the brace stiffness and the velocity exponent in the case of nonlinear viscous dampers are rather limited. In this paper, a numerical time-stepping method is developed for computing the seismic response of the structure with supporting braces and nonlinear viscous dampers. Using the proposed method, effects of the parameters of the nonlinear damper-brace systems are investigated, using first a single-story structure, followed by multi-story buildings. Results indicated that the design parameters for the dampers and supporting braces may be combined in numerous ways to satisfy a given set of structural performance objectives, but the brace stiffness can be minimized to achieve design efficiency in the range of velocity exponent commonly used for seismic applications of nonlinear viscous dampers. Results also indicated that for a set brace stiffness, if the dampers are optimally designed, the velocity exponent has an insignificant effect on the structural seismic performance objectives considered in this paper.

Semi-empirical model of internal pressure for a high-speed train under the excitation of tunnel pressure waves

To study the transmission of air pressure from external to internal carriage of high-speed trains, an internal pressure model excited by tunnel pressure wave is established. Firstly, factors affecting the air pressure transmission are analysed. Then, the semi-empirical models of the internal pressure caused by a single factor are established based on both the theoretical analysis and experimental data: (1) by applying the finite element method, effects of carbody deformation are studied; (2) based on the static air tightness test, the transmission from the gaps is modelled and (3) the model of the air ducts are surveyed on the base of the characteristics of the ventilation fans and valves. Finally, three routes are comprehensively considered and a coupling model of the internal pressure is established. Simulation results shows the model is adaptable in predicting the internal pressure under excitation of tunnel pressure waves. Besides, the effect of the factors on internal pressure are studied based on the models. Among the factors, the deformation has the least effect. Meanwhile, the air ducts are the dominant factor that affects the internal pressure at high opening degree, while the gaps will become the dominant factor when the opening degree of air ducts is relatively low.