Thermal cycling can reduce or eliminate thermal stresses in aluminum matrix composites, which is essential to improve the dimensional stability of the composites. In this work, the effect of thermal ...cycling process on the thermophysical properties of 6092 aluminum alloy/silicon carbide/zirconium tungstate composites was investigated by combining response surface optimization and multi-objective genetic algorithm. The purpose is to elucidate the effects of the process of heating temperature, heating time and cycles on the coefficient of thermal expansion (CTE), micro-strain and thermal conductivity of the composites. A series of robust response models were proposed and verified using analysis of variance, externally studentized residuals distribution and the predicted residuals distribution. According to these models, the heating temperature, heating time and cycles interact in a nonlinear manner concerning on thermophysical properties. The experimental results confirmed that thermal cycling can effectively reduce or eliminate thermal residual stresses in the composites and induce the phase transformation process of zirconium tungstate. The heating temperature plays a dominant role in promoting the thermal mismatch stress release between the metal matrix and the reinforcing particles. The Pareto-optimal hypersurface results on the response surface were obtained according to the non-dominated sorting genetic algorithms (NSGA-II), indicating that the optimal thermal cycling processes were 200 °C, 2 h and 3 cycles with corresponding CTE, micro-strain and thermal conductivity of 20.55 × 10
–6
/K, 1.16 × 10
–3
and 116.68 W/(m K), respectively.
The utilization of Co-Cr-Fe-based black pigments bears considerable significance within the realm of commercial ceramic pigments, owing to their distinctive spinel structure, remarkable ...high-temperature stability, and exceptional chromatic attributes. This study delves into the synthesis of diverse black pigment configurations by employing the co-precipitation method, leveraging the interplay of these three metallic oxides. This investigation encompasses a comprehensive scrutiny of ion valences, crystal structures and parameters, colorimetric properties, and their interrelationships. The methodology integrates the response surface methodology (RSM) framework, using theoretical formulations to navigate the material ratios and elucidating the associations between the resultant compositions and color coordinate values, aligned with the CIE-Lab* colorimetric methodology. The derived predictive models yielded an optimized black pigment composition, characterized by heightened black intensity and a refined formulation.
In many natural language processing tasks, e.g., text classification or information extraction, the weighted bag-of-words model is widely used to represent the semantics of text, where the importance ...of each word is quantified by its weight. However, it is still difficult for machines to understand a weighted bag of words (WBoW) without explicit explanations, which seriously limits its application in downstream tasks. To make a machine better understand a WBoW, we introduce the task of conceptual labeling, which aims at generating the minimum number of concepts as labels to explicitly represent and explain the semantics of a WBoW. Specifically, we first propose three principles for label generation and then model each principle as an objective function. To satisfy the three principles simultaneously, a multi-objective optimization problem is solved. In our framework, a taxonomy (i.e., Microsoft Concept Graph) is used to provide high-quality candidate concepts, and a corresponding search algorithm is proposed to derive the optimal solution (i.e., a small set of proper concepts as labels). Furthermore, two pruning strategies are also proposed to reduce the search space and improve the performance. Our experiments and results prove that the proposed method is capable of generating proper labels for WBoWs. Besides, we also apply the generated labels to the task of text classification and observe an increase in performance, which further justifies the effectiveness of our conceptual labeling framework.
Owing to their biocompatibility, chemical stability, film-forming ability, cost-effectiveness, and excellent electroactive properties, poly(vinylidene fluoride) (PVDF) and PVDF-based polymers are ...widely used in sensors, actuators, energy harvesters, etc. In this review, the recent research progress on the PVDF phase structures and identification of different phases is outlined. Several approaches for obtaining the electroactive phase of PVDF and preparing PVDF-based nanocomposites are described. Furthermore, the potential applications of these materials in wearable sensors and human energy harvesters are discussed. Finally, some challenges and perspectives for improving the properties and boosting the applications of these materials are presented.
Relation extraction is one of the most important tasks in information extraction. The traditional works either use sentences or surface patterns (i.e., the shortest dependency paths of sentences) to ...build extraction models. Intuitively, the integration of these two kinds of methods will further obtain more robust and effective extraction models, which is, however, ignored in most of the existing works. In this paper, we aim to learn the embeddings of surface patterns to further augment the sentence-based models. To achieve this purpose, we propose a novel pattern embedding learning framework with the weighted multi-dimensional attention mechanism. To suppress noise in the training dataset, we mine the global statistics between patterns and relations and introduce two kinds of prior knowledge to guide the pattern embedding learning. Based on the learned embeddings, we present two augmentation strategies to improve the existing relation extraction models. We conduct extensive experiments on two popular datasets (i.e., NYT and KnowledgeNet) and observe promising performance improvements.
The ion-adsorption rare earth deposit developed on the Mosuoying granite in the Panxi area of southwestern China represents a significant advancement in the exploration of ion-adsorption rare earth ...deposits in Sichuan. Being the first and currently the sole ion-adsorption rare earth deposit in Sichuan, studying its rare earth mineralization characteristics holds great importance. This paper aims to investigate the geochemical properties of the Mosuoying granite and its overlying weathered crust using rock geochemical methods based on field geological investigations. The findings reveal that the deposit belongs to the light rare earth type, with the ore-forming parent rock attributed to the high-potassium calc-alkaline series. It exhibits a high rock REE content ranging from 419 to 578 ppm, indicating favorable mineralization potential. Hydrothermal alteration reduces the REE content of the parent rock, leading to a notable increase in the LREE/HREE ratio, thus impacting the partitioning of rare earth elements and subsequent ore formation. The distribution characteristics of rare earth elements in each layer of the weathered crust are controlled by the parent rock and exhibit a light rare earth distribution pattern. The completely weathered layer is the main enrichment zone for rare earth elements, and the migration and enrichment patterns of rare earth elements in the weathered crust are evident. From the semi-weathered layer to the completely weathered layer, all REEs were gained, with a higher degree of migration for LREE. From the completely weathered layer to the clay layer, all REEs were lost, and the vertical distribution of rare earth content shows a “low-high-low” pattern.
In this report, PEDOT composite films were prepared by
electrochemical polymerization. 1-Ethyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide (EMI-TFSI) was used as an ionic liquid dopant for ...PEDOT:PSS films. Subsequently, these PEDOT:PSS/EMI-TFSI films were compared with PEDOT:PSS films based on their morphology, structure, electrochromic properties, and optical properties at different deposition voltages and deposition times. It was observed that the addition of EMI-TFSI enhanced all the aforementioned properties of the films. PEDOT:PSS/EMI-TFSI films were seen to have a larger ion diffusion coefficient (1.38 × 10
cm
·s
), a wider color change range (43.48%), a shorter response time (coloring response time = 1.2 s; fade response time = 2 s), and a higher coloring efficiency (189.86 cm
·C
) when compared with normal PEDOT:PSS films. The introduction of EMI-TFSI in the films ultimately resulted in superior electrochemical and optical properties along with higher stability.
The facile transition from hydrophilicity to superhydrophilicity and superhydrophobicity on aluminum alloy surface by acid etching and polymer coating.
•Acid etching and polymer coating were used to ...prepare a superhydrophilic and superhydrophobic surface on aluminum alloy.•The facile transition from hydrophilicity to superhydrophilicity and superhydrophobicity was readily realized by the simple method.•The superhydrophobic surfaces with a high water contact angle of 157̊ were obtained by the simple coating.
The transition from the hydrophilic surface to the superhydrophilic and superhydrophobic surface on aluminum alloy via hydrochloric acid etching and polymer coating was investigated by contact angle (CA) measurements and scanning electron microscope (SEM). The effects of etching and polymer coating on the surface were discussed. The results showed that a superhydrophilic surface was facilely obtained after acid etching for 20min and a superhydrophobic surface was readily fabricated by polypropylene (PP) coating after acid etching. When the etching time was 30min, the CA was up to 157̊. By contrast, two other polymers of polystyrene (PS) and polypropylene grafting maleic anhydride (PP-g-MAH) were used to coat the aluminum alloy surface after acid etching. The results showed that the CA was up to 159̊ by coating PP-g-MAH, while the CA was only 141̊ by coating PS. By modifying the surface with the silane coupling agent before PP coating, the durability and solvent resistance performance of the superhydrophobic surface was further improved. The micro–nano concave–convex structures of the superhydrophilic surface and the superhydrophobic surface were further confirmed by scanning electron microscope (SEM). Combined with the natural hydrophilicity of aluminum alloy, the rough micro–nano structures of the surface led to the superhydrophilicity of the aluminum alloy surface, while the rough surface structures led to the superhydrophobicity of the aluminum alloy surface by combination with the material of PP with the low surface free energy.
Cobalt blue ceramic pigments mainly consisting of CoAl2O4 are subject to the difficulty of color control. Here, a perspective is reported regarding research on the reasons for color change based on ...the control of the heat treatment and ratio of components. Macroscopically, the composition of pigment powders determines the color. Microscopically, the crystallite characters including size, cation distribution, and structure have an important effect on the color. The ingredient, structural, and color properties of the pigment powders are analyzed using thermo gravimetry–differential scanning calorimetry (TG–DSC), X-ray diffraction (XRD) measurement, Rietveld refinement, energy dispersive spectrometer (EDS), and colorimetry analysis. The color is proven to be associated with cation distribution, such as that of Co2+ and Co3+. It is indicated that high heating temperature, long heating time, and a large proportion of Al3+ can, respectively, induce the Co2+ and Al3+ in tetrahedral and octahedral sites.
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