Thermodynamic databases for multi-component aluminum alloys, PanAl, and magnesium alloys, PanMg, are reviewed and applications are highlighted. Precipitation simulations by combining thermodynamic and mobility databases for Al and Mg alloys with the PanPrecipitation module of Pandat are also demonstrated. These simulations can serve as virtual experiments to understand the effects of alloy composition and heat treatment condition on the target properties therefore provide guidance for the design of real experiments, save time and reduce cost. For PanAl the focus in this work is on 7xxx alloy and high throughput calculation (HTC) to understand/predict the effects of major and minor alloying elements on the selected properties of an alloy. For PanMg applications are exemplified in a wider spectrum of Mg alloy design and related processing parameters and the usefulness of the CALPHAD modeling tool in Mg technology is demonstrated. 相似文献
Aromatic polyimides (PIs) are high-performance polymers with rigid heterocyclic imide rings and aromatic benzene rings in their macromolecular backbones. Owing to excellent mechanical properties and thermal stability, as well as readily adjustable molecular structures, PIs have been widely adopted for many applications related to electronics, aerospace, automobile, and other industries. In recent years, PI fibers prepared by electrospinning of polyamic acid (PAA) precursor nanofibers followed by imidization (commonly known as electrospun PI nanofibers) have attracted growing interests. Herein, the preparation, evaluation, and application of electrospun PI nanofibers are reviewed. PI polymers and the electrospinning technique are introduced first followed by the preparation of electrospun nanofibers of homo-PI, co-PI, blend-PI, and PI composite. Subsequently, the mechanical and thermal properties of electrospun PI nanofibers are presented; in particular, the mechanical properties of individual electrospun PI nanofibers are highlighted. Thereafter, various applications of electrospun PI nanofibers are outlined, including reinforcement of composites, Li-ion battery separators, fuel cell proton exchange membranes, sensors, microelectronics, high-temperature filtration media, super-hydrophobic PI nanofibers, and PI-based carbon nanofibers. In the final section of conclusions and perspectives, future research endeavors and high-value applications of electrospun PI nanofibers are discussed. 相似文献
The aim of this in vitro study was to evaluate the effects of chlorhexidine gluconate (2%), sodium hypochloride (2.5%), ozone gas, and boric acid at different concentrations (1%, 3%, 5%, and 7%) on microleakage from composite restorations.
In a total of 80 extracted human canine teeth, a class V cavity was opened on the buccal surface and the samples were separated into eight groups. In the control group, no procedure was applied for cavity disinfection, then composite restoration (Z250, 3M) was made using single-stage, self-etch adhesive (Single Bond 3M). In the other groups, seven different disinfectants were used, then the cavity was restored. The teeth were split into two in the buccolingual direction, parallel to the long axes. Stain penetration was examined under stereomicroscope and scored. Examination with SEM was made on one sample from each group, selected at random. Statistical evaluations were made using Dunnett C Post Hoc Comparison and Kruskal–Wallis H tests.
In the occlusal region evaluation, the groups with the lowest level of leakage were the 3% and 5% boric acid groups, and the highest levels of microleakage were determined in the chlorhexidine group and the 1% boric acid group. In the gingival region, the lowest level of microleakage was in the 5% boric acid group and the highest levels were determined in the 1% and 7% boric acid groups.
Boric acid disinfectants used at suitable concentrations were not seen to create a risk in respect of microleakage. 相似文献
Automatic photo enhancement is one of the long‐standing goals in image processing and computational photography. While a variety of methods have been proposed for manipulating tone and colour, most automatic methods used in practice, operate on the entire image without attempting to take the content of the image into account. In this paper, we present a new framework for automatic photo enhancement that attempts to take local and global image semantics into account. Specifically, our content‐aware scheme attempts to detect and enhance the appearance of human faces, blue skies with or without clouds and underexposed salient regions. A user study was conducted that demonstrates the effectiveness of the proposed approach compared to existing auto‐enhancement tools.相似文献
The purpose of this study was to examine the effects of multimedia strategies for instructional techniques and practice on non-native novices' Chinese character learning performance and cognitive load. Two types of multimedia instructional presentations – radical-highlighted and stroke-pronunciation – and two types of practice – visual cue and voice cue – were implemented. Participants were 81 non-native novices randomly assigned to one of the four experimental groups, namely radical-highlighted visual-cue, radical-highlighted voice-cue, stroke-pronunciation visual-cue and stroke-pronunciation voice-cue. An Internet-based e-learning course on the basis of Chinese characters was implemented and delivered as experimental instruction using a Moodle platform. The results show that, for non-native novices, the stroke-pronunciation (SP) strategy of showing strokes with pronunciations is better than the radical-highlighted (RH) strategy, enabling the novices to achieve better performance in identifying Chinese radicals. The significant two-way interactions suggest that (1) the SP presentation should be delivered with the voice-cue (VoC) practice to elicit better performance in writing and in identifying characters and strokes, and (2) the RH presentation should be delivered with visual-cue (ViC) practice to elicit better performance in character writing. Furthermore, participants showed similar levels of perceived cognitive load toward the stroke-based task and the radical-based task. However, when the SP presentation was delivered with the VoC practice, participants revealed lower perceived cognitive load toward the writing task. 相似文献
The design and practical applications of excilamps having a dielectric barrier and capacitive structure and driven by nanosecond, high voltage pulses are described. A simple design lamp having forced cooling and an excitation generator was demonstrated to have a lifetime of more than one thousand hours. The results of an experimental study of capacitive and high voltage nanosecond discharge-driven excilamps are presented. The influence of the excitation regime and operating gas mixture pressure on the dielectric barrier discharge (DBD) driven excilamps' efficiency is discussed. The discharge formation and output radiation dynamics of DBD driven excilamps was experimentally studied for the first time.The practical applications of several lamps designed in the High Current Electronics Institute, Tomsk, Russia to photochemistry, photobiology and photomedicine are discussed. 相似文献
Spatial ability has been recognized as one of the most important factors affecting the mathematical performance of students. Previous studies on spatial learning have mainly focused on developing strategies to shorten the problem-solving time of learners for very specific learning tasks. Such an approach usually has limited effects on improving the mathematical performance of students. In this study, a cognitive analysis approach is proposed for developing spatial learning tools by taking game characteristics into consideration. Moreover, the validation of the cognitive components of the spatial sense test for constructing two different kinds of intervention is verified, and the effects of the interventions are compared. To evaluate the performance of the proposed approach, an experiment was conducted on the mathematics course of an elementary school. The experimental results show that the spatial learning tool promotes not only the learning achievement, but also the spatial sense of the students. 相似文献
The American Psychological Association's Award for Distinguished Scientific Applications of Psychology is presented to a person who, in the opinion of the Committee on Scientific Awards, has made distinguished theoretical or empirical advances leading to the understanding or amelioration of important practical problems. The 2010 award was given to David M. Clark. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
The diesel engines are energy efficient (1), but their particulate matter (soot) emissions are still a matter of concern even though major advances in their control are being made. For soot abatement, catalytic diesel particulate filter (DPF) technique is widely employed to trap and burn the soot. Many types of catalysts have been investigated for the soot combustion i.e. platinum group metal (PGM) based, perovskite-type oxides, spinel-type oxides, rare earth metal oxides, and mixed transient metal oxides etc. The cost of PGM catalysts is high and their availability is questionable. Further they are susceptible to poisoning and have low thermal stability. On the other hand perovskite catalysts show potential as effective soot oxidation catalyst for the DPF because of their low cost, high thermal stability and tailoring flexibility. Many papers related to soot oxidation over perovskite catalysts have been published but no review paper appears in the literature that is dedicated to soot oxidation. Thus, this article provides a summary of published information regarding pure and substituted perovskite catalyst, preparation methods, properties, and their application for diesel soot emission control. 相似文献