Additive Eigenvalue Problems of the Laplace Operator with the Prescribed Contact Angle Boundary Condition

Additive eigenvalue problem appears in ergodic optimal control or the homogenization of Hamilton–Jacobi equations. It has wide applications in several fields including computer science and then attracts the attention. In this paper, we consider the Poisson equations with the prescribed contact angle boundary condition and finally derive the existence and the uniqueness of the solution to the additive problem of the Laplace operator with the prescribed contact angle boundary condition

Application of Improved Fuzzy-Set Pair Analysis in Mine Water Environmental Quality Evaluation

Mine water is an important water resource, mine water resource is of great significance to realize the sustainable development of economy and society, and the evaluation of water quality is an important link of mine water resource. This paper will be improved in Nemerow index method is applied to the fuzzy-set pair analysis method of composite algorithm, and the water quality evaluation of Kongzhuang Mine in Xuzhou is carried out. Finally, compared with the evaluation results of set pair analysis method and grey clustering method, it is shown that the evaluation results of this method are reasonable and scientific, which can provide reliable basis for the utilization of mine water resources

Current fluctuations reduction strategy based on optimal three‐space‐vector pulse‐width modulation for service‐life improvement of DC‐link electrolytic capacitors in three‐phase voltage‐source inverter system

Abstract The authors propose a current fluctuation reduction strategy based on optimal three‐space‐vector pulse‐width modulation (TSVPWM), which is used to improve the service‐life of the dc‐link electrolytic capacitors in two‐level three‐phase voltage‐source inverter (VSI) system. Differing from the typical SVPWM‐based method that employs two adjacent active voltage vectors and zero voltage vectors to synthesise the reference voltage, the proposed strategy selects the required voltage vectors based on the minimum dc‐link electrolytic capacitor current fluctuation. With the proposed strategy, an objective function for the root‐mean‐square value of dc‐link electrolytic capacitor current is first constructed under the constraint of eight permissible voltage vectors. And then, by solving the minimum of the objective function through the piecewise linear programming, the optimal three voltage vectors under the different modulation ratios and load power factors are obtained accordingly, so as to achieve the minimum dc‐link electrolytic capacitor current fluctuations during each switching period. Meanwhile, a PWM implementation scheme based on positive–negative double carrier signals is presented, which not only simplifies the implementation process but also effectively reduces the switching losses of power devices. Finally, the experimental results demonstrate that the proposed strategy can minimise the dc‐link electrolytic capacitor current fluctuation under different working conditions

Palladium-Catalyzed Decarboxylative Synthesis of Arylamines

A novel approach has been developed for the synthesis of arylamines via the palladium-catalyzed intramolecular decarboxylative coupling (IDC) of aroyloxycarbamates, obtained in situ by reacting aryl carboxylic acids with hydroxycarbamates. The reaction offers facile access to structurally diverse arylamines with the site-specific formation of the C­(sp²)-N bond under mild conditions

Risk Assessment of Water Inrush of a Coal Seam Floor Based on the Combined Empowerment Method

With the exploitation of the lower coal seams of the Taiyuan Formation, the Ordovician limestone water inrush in the floor became more serious. This paper considers the 162 and 163 mining areas of the Jiangzhuang Coal Mine, in Shandong Province, China. A comprehensive analysis of the geological and hydrogeological conditions of the mining area revealed the following: water pressure and water richness provide the water source and power for the floor water inrush; the thickness of the effective aquifer and the ratio of brittle rock can restrain floor water inrush; fault structures provide water inrush channels; and mining damage is an artificial interference and increases the probability of water inrush. Therefore, six factors: the water pressure of the Ordovician limestone aquifer, water abundance of the Ordovician limestone aquifer, equivalent thickness of effective aquifuge, brittle rock ratio, fracture structure, and mining destruction were selected as the influencing factors on water penetration of the bottom plate, and drawing software was used to establish a mining area map of related factors. The improved fuzzy hierarchical analysis method is more suitable for analyzing multi-objective decisions than the traditional hierarchical analysis method, but the weighting of results is influenced by expert experience. The entropy weight method is data-driven, and the empowerment results are objective. The improved fuzzy analytic hierarchy process and entropy weight method were coupled together, to determine the weight of each factor. The new method is not only data driven, but also takes empirical experience into consideration, making the empowerment results more reasonable. An evaluation of coal floor water inrush was established using MapGIS10.6, which is a general tool-type geographic information system software developed by the China University of Geosciences; and the risk of Ordovician limestone water inrush in the floor of the study area was classified into four levels: dangerous, relatively dangerous, relatively safe, and safe. The whole evaluation process is simple, but the evaluation results have practical importance and are very efficient, providing theoretical support for coal mine water prevention and control engineering

Changes of 5-hydroxymethyl-2-furfural in fresh and processed ginsengs

The study estimated changes of 5-hydroxymethyl-2-furfuraldehyde (5-HMF) in different ginseng products with different temperatures and time pretreatment. Heat treatment was performed at various temperatures for 1.50, 2.00, 2.50, and 3.00 hr, respectively. Ultrasonic extraction and reflux extraction were used to evaluate the extraction rate and different solvents (such as 80% methanol, dichloromethane, ethyl acetate, and an extraction with both dichloromethane and ethyl acetate solvents) using two extraction methods (liquid–liquid extraction and solid-phase extraction) to remove matrix interference. An ultraperformance liquid chromatography–mass spectrometer (UPLC-MS) method was used for quantitative and changing analysis of 5-HMF in different ginseng samples. The results indicated that the content of 5-HMF increased dramatically with heating temperature and time, and the 5-HMF in the ginseng samples ranged from 0.01 to 112.32 g/kg protein. The highest value was observed in the honey-added ginseng samples with the highest amount of addition and highest temperature treatment, and the lowest value was found in the fresh ginseng samples. These results implied that 5-HMF may be as an indicator to estimate the honey addition level and heat treatment degree during the processing of ginseng products, and the content of 5-HMF is a promising parameter to evaluate the quality of products (ginseng). The production and regulation of potentially harmful Maillard reaction products (PHMRPs)-5-HMF in ginseng manufacture will provide an important reference for safe ginseng processing

Regioselective Synthesis of 2‑Vinylanilines Using <i>O</i>‑aroyloxycarba-mates by Sequential Decarboxylation/Amination/Heck Reaction

A new sequential approach for 2-vinylanilines utilizing aryl carboxylic acids as stable, inexpensive and widely available arylating reagents is described. Employing a Pd-POVs catalyst system, this protocol is not only overcoming the restriction barrier of decarboxylative coupling to <i>ortho</i>-substituted substrates, but also provides site-special to create new C­(sp²)-N and C­(sp²)-C­(sp²) bonds. Mechanistic experiments suggest the cleavage of C­(sp²)-COOH gives priority to C­(sp²)-X bond in this reaction