A newly
heterogeneous palladium catalyst has been synthesized by
immobilizing Pd(OAc)2 onto a nitrogen-rich heptazine-based
porous framework (Cy-pip). Highly dispersed Pd particles and abundant
distributed N atoms in the framework make Pd/Cy-pip very efficient
toward the Suzuki–Miyaura reaction in aqueous medium at 40
°C without inert atmosphere and phase transfer agents. Pd/Cy-pip
catalytic system is superior to many POPs supported Pd catalysts such
as Pd/COF-LZU1, Pd@CNPCs, Pd-CIN-1, and MsMOP-1 that required toxic
organic solvents or high temperature. Furthermore, the strong interaction
between N donor sites and Pd nanoparticles in the framework extends
excellent recyclability without significant deactivation of the catalyst
after five cycles.
Water inrush is one of the major mining disasters that may lead to numerous casualties. The development of information techniques makes it possible to monitor the occurrence and evolution of water inrush. Then, locating monitors for water inrush becomes a primary problem. This study presents a method of optimal location of water level sensors by constructing a set covering model. The monitoring scope of the water level sensor at each location in a given time is computed first based on the numerical simulation of water spreading along mine tunnels. In this simulation, the water inrush quantity is assigned using the mine drainage capability over which an accident may occur. Then the greedy algorithm is used to optimize the number and positions of water level sensors. As results, a mine water disaster can be monitored in the given time after it happened. The proposed method is then verified in the Beiyangzhuang coal mine in the North China. The results show that at least 22, 36, 42, 64 and 106 water level sensors are needed to monitor water disasters in the whole mine within 60, 30, 20, 10 and 5 min, respectively.
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