The cure kinetics of tetrafunctional epoxy resins with three different backbone structures and their modification by polydimethylsioxane (PDMS) were studied by means of differential scanning ...calorimetry with dynamic approach. The development of epoxy networks was characterized by dynamic viscoelastic measurements. Results showed that all the epoxy resins obeyed the autocatalytic reaction mechanism with a reaction order of about 3. Epoxy resin with softer aliphatic backbone demonstrated a higher cure reactivity and stronger tendency towards autocatalysis, as well as lower crosslinking density. The PDMS-modified epoxy resins showed higher early cure reactivity and a lower crosslinking density due to the plasticization and restriction effect of the dispersed PDMS phase, respectively. Based on cure kinetics and dynamic viscoelastic results, the αm was found to be an effective precursor for describing the developing of epoxy networks during the course of cure.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
In this paper, we propose a new structured measurement matrix for practical compressed sensing based on block weighing matrix, called partial Random Block Weighing Matrix (pRBWM). The proposed pRBWM ...is universal with a variety of sparse signals and provides high reconstruction performance simultaneously. In addition, with the sparse and circulant block structure, these new measurement matrices feature low-memory requirement and low computational complexity in reconstruction. Moreover, it can be more easily implemented in hardware thanks to its sample elements and the application of Chaos-based permutation operator in construction of pRBWM. Simulation results demonstrate that the proposed pRBWM performs comparably to, or even better than completely random matrices and many other structured matrices. And the proposed pRBWM forms a high balance between reconstruction performance,storage and computational complexity and hardware implementation.
•A structured measurement matrix for practice compressed sensing is proposed.•The measurement matrix is mainly based on block weighing matrix.•The measurement matrix has high sparsity and block circulant structure.•The performance of the measurement matrix is proved to be near optimal.•Chaos-based permutation operator is introduced for hardware implementation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
A large percentage of students who use Internet search engines accept the results they are given without challenge, which conflicts with many learning theories that emphasize exploration. Longer and ...more in-depth searches require critical analyses of results as part of a process that is thought to produce better learning outcomes. With the development of social media, social motivation is increasingly considered an important factor in learning. To boost motivation for knowledge exploration, many instructors are adding elements of high interest to students to their teaching materials and activities. Here we investigate the effects of social motivation-associated priming on learner behaviors involving search engine results, using differences in learner characteristics (peer relationships and math skills) and search question type (add-on and integrated) as the main distinguishing factors. Our sample consisted of 81 students between the ages of 14 and 15 in a junior high school located in northern Taiwan. All of the participants were experienced in using computers, the Web, and search engines. Our results indicate (a) no significant effects of peer relationships or prior math achievement on the use of search results in that subject area; (b) the use of add-on questions (i.e., presenting math questions after presenting interpersonal relationship questions) encourages the appropriate use of summary results; and (c) the use of integrated questions (i.e., learners read stories involving a mix of interpersonal relationship and math information before addressing search questions) encourages students to read more information from search results rather than focusing on finding single “correct” answers. We interpret the third finding as evidence of greater enjoyment of exploration.
•Effects of social motivation on learner use of search engine results are discussed.•Neither peer relationships nor math scores affected the use of search results.•Social topic search tasks positively affected the use of search results.•Question order promoted participant interest in answering questions.•Questions integrated into stories encouraged greater search depth.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Our photocatalyst possesses homo/heterojunction structure, which consists of hexagonal CdS, cubic CdS and Prussian blue. This design of homo/heterojunction structure not only achieves ideal energy ...band structure, which makes for stable and rapid separation of photogenerated electrons-holes, but also improves stability of photocatalyst in various extreme circumstances. Therefore, the photocatalytic activity is significantly enhanced.
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•The homo/heterojunctions structures were designed via one-pot kinetic regulation.•The rational energy band distribution enhances photocatalytic activity.•The strong chelation between cyanogroups and Cd2+ improve the stability.•The photocatalysts possess excellent reusability.
Photoreduction of soluble U(VI) to insoluble U(IV) by CdS-based catalysts shows great potential in remediating radioactive wastewater in terms of environmental friendliness and desirable bandgap as well as the availability of CdS, but is still limited by undesirable efficiency and stability from photogenerated carrier recombination and photocorrosion. Herein, we have elegantly designed tailor-made CdS@Prussian blue with homo/heterojunctions via one-pot kinetic regulation. The key to such a structure is to leverage the outstanding binding affinity between cyanogroups of Prussian blue and Cd2+ to create diversity of local precursor concentration differences. With such unique structure and rational energy band distribution, our photocatalysts demonstrate an unprecedented U(VI) removal efficiency as high as 2.5 times that of the pristine CdS. More importantly, the strong chelation between cyanogroups and Cd2+ endows our catalysts with extremely excellent stability compared with other state-of-the-art composite photocatalysts. This work provides a facile and universal inspiration for homo/heterojunction engineering of high-performance photocatalysts for photoreduction of uranium.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The performance of Capacitive Voltage Transformer (CVT) degrades over time, making measurement error monitoring a research hotspot in the field of smart grid. At present, these are several challenges ...such as complex data features, a lack of criteria for selecting optimal measurement models, and low precision. CVT measurement errors can be classified into ideal error and additional one. The former is typically evaluated via mutual information and redundancy within the topology-level transformer group. Considering that a single model cannot process the time series, strong randomness and nonlinearity of the additional error, the Stacking model is selected. Based on the principle of heterogeneity and high-quality, correlation coefficient and feature contribution degree, Random Forest, eXtreme Gradient Boosting, Ridge Regression, K Nearest Neighbors, Support Vector Regression, and Long Short-Term Memory are chosen as base learners through correlation and feature contribution analysis; while extra-trees with strong generalization and robustness is chosen as the meta learner. To improve the measurement precision, the attention-like mechanism is used to scale time and accuracy weights. Finally, according to the power domain knowledge, a linear superposition model is developed to fuse the ideal and additional errors, and thus realize online error measurement for CVTs. The experimental results indicate that the improved Stacking model outperforms mainstream measurement models by an average reduction of 59.47%, and 52.58% in the root mean squared error and the mean absolute error with the best R2 closest to 1. It not only effectively improves the accuracy but also meets speed requirement for online error measurement.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The terahertz (THz) spectra of chlorothalonil have been investigated from experimental spectrum and theoretical simulation in range of 0.4-3.0 THz. Based on terahertz time-domain spectroscopy ...(THz-TDS), the absorption and refraction spectra of chlorothalonil were obtained. To analyze the experimental spectrum, making up for the deficiency of isolated-molecule analysis, the structural changes and vibrational absorption spectrum of chlorothalonil were calculated in solid-state form, then analyze the source of absorption peaks. The results clearly demonstrate that the solid-state theory simulation is in good agreement with experiment where isolated-molecule simulation is not able to reproduce the spectral features, and the solid-state theory simulation complete the assignment of eleven absorption peaks. The observed spectral features of chlorothalonil molecule mainly originate from intra-molecular interactions of Cl-C-C, N-C-C and crystal packing vibrations in crystalline unit cell.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
AbstractThe network-based real-time kinematic (NRTK) global navigation satellite system (GNSS) technique was proposed for the first time to monitor the dynamic response of bridges. It could receive ...corrections from an established remote continuously operating reference station (CORS) network instead of a user-defined local reference station. To validate the feasibility of the NRTK-GNSS technique, laboratory and field experiments were both conducted at the University of Nottingham, U.K., and the Wilford suspension bridge, a footbridge close to the university’s campus. The conventional real-time kinematic (RTK)-GNSS and accelerometer techniques were synchronously considered for validating the accuracy of the NRTK-GNSS technique. A wavelet packet filtering scheme was designed to process full-scale experimental data according to the characteristics of NRTK-GNSS measurement noise. The dynamic displacements and vibration frequencies of the bridge were successfully identified from the NRTK-GNSS data with satisfactory accuracy. In conclusion, the study confirms that the proposed NRTK-GNSS can be a potential technique for the dynamic monitoring of bridges, with adequate performance and lower operational cost. It will be a powerful monitoring tool for structural health monitoring with continuous enhancement in the hardware and algorithm.
•IEMFAFE is proposed to conduct business integration of arable farm enterprises.•The modeling methods of product, resource, organization, and process views are proposed.•A multi-case study shows ...IEMFAFE is well suited to modeling arable farm enterprises.
With the increasing integration of information technology in arable farms, enterprise integration (EI) is becoming increasingly important. As farms handle many applications, all of which work in isolation from one another, integrating these disparate systems to create unity across the enterprise has clear value. One critical aspect of EI is business integration, which helps the enterprise align the use of technology assets with the business to achieve strategic goals. While existing enterprise modeling (EM) methods are often used to model industrial or general enterprises for business integration, they do not fully meet the needs of arable farm enterprises. This study aims to propose an EM framework for arable farm enterprises that provides an effective and practical method for business integration. Therefore, an integrated EM framework for arable farm enterprises (IEMFAFE) is proposed using a domain analysis approach based on EM theory. Additionally, steps and methods for modeling arable farm enterprises based on IEMFAFE are provided. A multi-case study shows that IEMFAFE is well suited for modeling arable farm enterprises. The high expressiveness of IEMFAFE enables accurate descriptions of enterprise details and extraction of the service modules and information entities necessary for system design, significantly improving the speed and quality of the system design. The contributions of this study will benefit both researchers investigating the integration of arable farm enterprises and practitioners aiming to architect integrated farm management information systems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The presence of complex geometric and radiometric differences in multimodal remote sensing images poses a significant challenge for the existing image matching methods. In this letter, we propose a ...robust multimodal remote sensing image matching method based on an enhanced oriented self-similarity (SS) descriptor. Based on our previous oriented SS descriptor, the assigned main orientations are refined by introducing a Gaussian smoothing function to improve robustness, and the redundant information is eliminated by downsampling the descriptor neighborhood to improve efficiency. In addition, we design a position-weighted matching (PWM) method to optimize the matching performance. Experimental results on three types of multimodal remote sensing image datasets comprising 75 image pairs demonstrate that the proposed method surpasses the existing methods and exhibits superior robustness in achieving successful matching, with a success rate (SR) of 100%. Our executable program and datasets are available for public download in https://github.com/Xxin08/EOSS .
