A wideband neutralization line is proposed to reduce the mutual coupling of a compact ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna. With the introduced decoupling method, the ...designed UWB MIMO antenna covers the band of 3.1-5 GHz with an isolation of higher than 22 dB. The proposed wideband neutralization line is not necessarily placed in the clearance area between two MIMO elements and can be put above the copper ground. A small clearance (antenna area) of 35 ×16 mm 2 is achieved. The designed UWB MIMO antenna is fabricated. Sparameters, radiation patterns, total efficiency, and realized gain of the prototype are measured and compared to the simulations.
A magnetic CdS quantum dot (Fe3O4/polydopamine (PDA)/CdS) was synthesized through a facile and convenient method from inexpensive starting materials. Characterization of the prepared catalyst was ...performed by means of FTIR spectroscopy, XRD, SEM, TEM, energy‐dispersive X‐ray spectroscopy, and vibrating‐sample magnetometer techniques. Fe3O4/PDA/CdS was found to be a highly active photocatalyst for the amidation of aromatic aldehydes by using air as a clean oxidant under mild conditions. The photocatalyst can be recovered by magnetic separation and successfully reused for five cycles without considerable loss of its catalytic activity.
Going greener: Magnetic CdS quantum dots are designed for application as an efficient photocatalyst for the oxidative amidation of aldehydes by using air as the oxidant under mild conditions. The photocatalyst can be recovered by magnetic separation and successfully reused in five cycles without considerable loss of catalytic activity.
The main aim of the present study is to explore and compare three state-of-the art data mining techniques, best-first decision tree, random forest, and naïve Bayes tree, for landslide susceptibility ...assessment in the Longhai area of China. First, a landslide inventory map with 93 landslide locations was randomly divided, with 70% of the area used for training landslide models and 30% used for the validation process. A spatial database of 14 conditioning factors was constructed under a geographic information system environment. Subsequently, the ReliefF method was employed to assess the prediction capability of the conditioning factors in landslide models. Multicollinearity of these factors was verified using the variance inflation factor, tolerance, and Pearson's correlation coefficient. Finally, the three resulting models were evaluated and compared using the area under the receiver operating characteristic (AUROC) curve, standard error, 95% confidence interval, accuracy, precision, recall, and F-measure. The random forest model showed the AUROC values (0.869), smallest standard error (0.025), narrowest 95% confidence interval (0.819–0.918), highest accuracy value (0.774), highest precision (0.662), and highest F-measure (0.662) for the training dataset. Thus, the random forest model is a promising technique that could be used for landslide susceptibility mapping.
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•The effectiveness of three advanced models is compared.•Predictive capability and multicollinearity of landslide factors are analyzed.•The performance of the maps has been validated against historical landslide data.•The RF model outperforms the other models.
We review the most recent advances in tribological studies of 2D materials, with particular focus on the unique mechanisms underlying their novel friction and wear behaviors. Based on the fundamental ...understandings, the impacts of atomic structures of shearing interfaces and environmental factors are summarized and various strategies for achieving friction modulation and superlubricity are discussed. Finally, prospects toward practical applications of 2D materials in engineering mechanical systems are presented.
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Two-dimensional (2D) materials are crystalline materials made of a single or a few layers of atoms. They have been an active research subject in recent years because of their unique physical and chemical properties. In particular, 2D materials such as graphene, hexagonal BN, and MoS2 exhibit some of the lowest friction coefficients and wear rates, making them attractive for enhancing the efficiency, durability, and environmental compatibility of future mechanical systems. This review will focus on recent advances in the tribology of 2D materials. Starting from general physical characteristics, the essential friction and wear behavior of 2D materials together with the associated mechanisms are reviewed for both interlayer and surface sliding. Influences of the atomic structures of the slip interfaces and environmental factors are discussed, with special attention given to various strategies for achieving friction modulation and superlubricity. Finally, the emerging engineering applications of 2D materials, as well as future prospects, are summarized.
The Documentary Hypothesis proposed by Julius Wellhausen has sparked discussions for over a century. The core of this debate revolves around the perspective through which the creation of the Torah ...should be viewed. Previous studies have often neglected the focus on “people”. The Torah was created by individuals and was profoundly influenced by the era in which they lived. In this specific study, instead of concentrating on the texts or historical background, we should focus on the “authors” or “redactors”, exploring how they processed and created the texts under the influence of their times. In Jewish history, the destruction of the Northern Kingdom and the Southern Kingdom played a crucial role in the creation of the Torah. After the fall of the Northern Kingdom, the Deuteronomists, reflecting on historical lessons, formulated a set of legal norms for theology and society, which established theological standards for further interpreting and writing ancient Jewish history. Following the destruction of the Southern Kingdom, Diaspora group and Returnees, centered on reflecting on their catastrophes and responding to contemporary crises, further created and integrated texts of ancestral traditions and the Promised Land, embedding the historical memory of ancestors-land for the Jewish people.
Charles Tilly's theory of capitalized coercion based on the historical experience of Western Europe has now been widely accepted by historical sociologists. However，his difficulties in dealing with ...the English polity require us to gain a deeper understanding of England's efforts to transform ancient constitution in order to establish a modern government that could accommodate the popular demands of liberty as well as respond to the international competitions.Hume's analysis of the Glorious Revolution offers us valuable insights. Faced with international challenges，the King attempted to strengthen the state power through a series of unconventional religious and military policies that had threatened the political tradition. It provoked widespread suspicions that the monarch intended to replace English liberty with French absolutism，which eventually led to the outbreak of revolution. The Glorious Revolution transformed ancient constitution by restricting prerogative and giving priority to popular principles that
Organic donor–acceptor systems have attracted much attention due to their various potential applications. However, the rational construction and modulation of highly ordered donor–acceptor systems ...could be a challenge due to the complicated self‐assembly process of donor and acceptor species. Considering the well‐defined arrangement of species at the molecule level, a crystalline host–guest system could be an ideal platform for the rational construction of donor–acceptor systems. Herein, it is shown how the rational construction of highly tunable donor–acceptor materials can be achieved based on a crystalline host–guest platform. Within the well‐established metal–organic framework NKU‐111 as the crystalline host enabled by the relatively stable coordination‐directed assembly, the introduction and arrangement of guest molecules in the crystals allow the rational construction of the NKU‐111⊃guest donor–acceptor system. The donor–acceptor interaction in the systems can be readily modulated with different guest molecules, which can be justified by the well‐demonstrated guest‐dependent characteristics. Accordingly, the NKU‐111⊃guest reveals highly tunable donor–acceptor properties such as charge‐transfer‐based emissions and electrical conductivity. This work indicates the potential of crystalline host–guest systems as an ideal platform for systematic investigations of donor–acceptor materials.
A donor–acceptor material based on a host–guest crystalline material platform is raised. As a proof of concept, a metal–organic framework (NKU‐111) is utilized as a host acceptor for the accommodation of aromatic donor guests. The resulting donor–acceptor system features highly tunable charge‐transfer‐based emissions and conductivity, indicating the rationality and efficiency of this strategy.
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•Hoeffding Tree is a promising landslide susceptibility model based on ROC and AUC.•Bayes Network and Logistic Model Tree were applied for comparison.•Correlation analysis of ...conditioning factors was completed by Frequency Ratio.•Landslide susceptibility maps of Muchuan County and the county town were produced.
Landslides, one of the most common hazards around the world, have brought about severe damage to life and property of human. To prevent and mitigate landslides, various models have been introduced to assess landslide susceptibility. In this paper, Hoeffding Tree (HT), a prevailing data stream mining algorithm, was employed to predict landslide susceptibility in Muchuan County, China for the first time. Meanwhile, Logistic Model Tree (LMT) and Bayes Network (BN) were applied to produce landslide susceptibility maps for comparison. The model performances were evaluated by Receiver Operating Characteristic (ROC) curves and areas under the curves (AUC). To obtain landslide inventory map, 279 landslides data was collected, and training and validation datasets were randomly divided with a proportion of 70% to 30%. Furthermore, twelve conditioning factors (altitude, slope angle, profile curvature, plan curvature, slope aspect, distance to roads, distance to rivers, TWI, NDVI, soil, land use and lithology) were selected to construct landslide susceptibility models. Moreover, correlations between conditioning factors and landslides were analyzed using Frequency Ratio (FR). The results showed landslides are prone to occur in areas where human activities concentrate, and all three models exhibited satisfying performances. Concretely, for training dataset, LMT model showed the highest AUC (0.854), followed by HT (0.726) and BN (0.709). However, for validation dataset, LMT and BN models generated similar AUC values (0.761 and 0.764 respectively), and the highest AUC value belonged to HT (0.802). The distributions of landslide susceptibility zones revealed that the interior of county town is mainly seated in low and very low susceptibility zones, whereas regions close to the border suffer high and very high landslide risk. The results acquired in this paper are significant to landslide prevention and urban planning in Muchuan, China. Additionally, this study proved that HT model is a promising classifier for landslide susceptibility modeling.
Out-of-step oscillation is a very destructive physical phenomenon in power system, which could directly cause big blackout accompanied by serious sociology-economic impacts. Out-of-step splitting ...control is an indispensable means, which could protect the system from major shocks of out-of-step oscillation. After years of development, it has achieved certain amount of research results. Have the existing methods been able to meet the requirements of out-of-step splitting? What improvements are needed? Under this background, this review is written. It combs the development of out-of-step splitting control technologies and analyzes the technical routes and characteristics of different methods. It points out the contradiction between rapidity and optimality is the biggest technical problem, existing in both the traditional local measurement based out-of-step splitting protection and the wide-area information based out-of-step splitting protection. It further points out that the advantages of the two types of protections can be combined with the unique physical characteristics of the out-of-step center to form a more advantageous splitting strategy. Besides, facing the fact of large-scale renewable energy access to power grid in recent years, this review also analyzes the challenges brought by it and provides some corresponding suggestions. It is hoped to provide some guidance for the subsequent research work.
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