Synthesis, characterization of bimetallic Sn-Zn-MCM41 and its catalytic performance in the hydroxylation of phenol

A series of Sn-Zn modified-MCM41 has been synthesized by direct hydrothermal method and characterized using ICP, XRD, TG/DTA, FT-IR, HRTEM and N_2-adsorption techniques. Catalytic performances of the obtained materials were evaluated in the hydroxylation of phenol with H₂O₂. Results indicated that all the samples exhibited typical hexagonal arrangement of mesoporous structure with high surface area and the heteroatoms were probably incorporated into the framework of MCM41. Catalytic tests revealed that the bimetallic incorporated materials were effective catalysts in the hydroxylation of phenol. The conversion of phenol could be reach to 56.8% for the catalysts with Sn: Zn: Si = 2.69: 4.57: 100 (molar ratio) under the optimized reaction conditions. Moreover, the materials containing Sn and Zn exhibited higher catalytic activity than monometallic Sn and Zn modified MCM41.     

拟建鄱阳湖水利枢纽对湖区水环境容量的影响

采用水动力水质模型模拟了鄱阳湖在极端退水年(2016年)和一般退水年(2017年)两种退水工况下拟建鄱阳湖水利枢纽建设前后的水动力水质过程,并构建湖区水环境容量模型评估了鄱阳湖拟建水利枢纽对湖区水质和水环境容量的影响。模拟结果表明：枢纽建设运行能显著增加鄱阳湖的水体体积,每月最大可增加77%;在退水初期主要降低湖泊中部的TP质量浓度,在极端退水年的退水后期会导致闸上TP质量浓度升高,在一般退水年则会导致闸上TP质量浓度降低,但对COD_Mn和NH₃-N质量浓度空间分布无明显影响;在极端退水年,枢纽建设运行会导致COD_Mn、NH₃-N和TP质量浓度增大,而在一般退水年则会导致TP的质量浓度降低;枢纽建设运行能显著提升COD_Mn和NH₃-N的水环境容量,在一般退水年会增大TP的水环境容量,但在极端退水年TP的水环境容量可能降低。     

纳米自组装大孔催化剂对催化裂化柴油的加氢催化性能

采用二次纳米自组装方法制备出具有大孔道的催化剂0106、1227,两种纳米自组装催化剂在30～100 nm孔径分布分别占11％、28％。纳米自组装催化剂具有低堆积密度和高金属含量等特点。在10 mL固定床微型反应器中,以镇海炼化的催化裂化柴油为原料,在温度360℃、压力7 M Pa、氢油体积比为600∶1、体积空速为1．5 h-1条件下,考察了两种纳米自组装催化剂的初活性评价,并与现有工业催化剂作对比。结果表明,两种纳米自组装催化剂0106、1227可使催化裂化柴油的含硫质量分数从12400μg/g分别最低降到483、283μg/g ,最高脱硫率分别为96．10％、97．71％;将含氮质量分数从1507μg/g分别最低降到35．7、14．0μg/g ,最高脱氮率分别为97．63％和99.00％;其最高芳烃饱和率分别为67．99％和68．88％;而参比催化剂仅可使催化裂化柴油的含硫质量分数从12400μg/g最低降到537μg/g ,最高脱硫率为94．57％;将含氮质量分数从1507μg/g最低降到64．6μg/g ,最高脱氮率为95．54％;其最高芳烃饱和率为65．65％。     

Biodegradation of catechol by Pseudomonas fluorescens isolated from petroleum‐impacted soil

Bioremediation strategies have been applied to clean up petroleum hydrocarbon (PHC) impacted sites. Introducing PHC degrading microorganisms (bioaugmentation) and enhancing the in‐situ nutrients availability (biostimulation) are widely used strategies. These strategies can be combined to lead to a better bioremediation performance. In this work, Pseudomonas fluorescens was isolated from a PHC impacted site. Through a 2³ factorial design plan, the effect of various combinations of nitrate, sulphate, and phosphate ions on the PHC bioremediation performance by P. fluorescens was investigated using catechol, an essential metabolic intermediate of BTEX degradation, as the sole carbon source. The maximum specific catechol degradation rate was chosen as the response to evaluate the catechol bioremediation performance. The ANOVA results indicated that the presence of nitrate ions alone lowered the maximum specific catechol degradation rate, which can be explained by the accumulation of nitrites and ammonia during the denitrification process by P. fluorescens. It was noted that dosing sulphate ions alone did not affect the bioremediation performance, which indicates P. fluorescens can grow in a sulphur‐limited environment. In contrast, the presence of sulphate and nitrate ions together can lead to a higher specific catechol degradation rate. This may be caused by the presence of sulphate that can suppress the production of nitrites. The importance of phosphate ions on catechol biodegradation was investigated. The absence of phosphate led to incomplete biodegradation. Introducing phosphate ions can accelerate catechol degradation, which can be explained by the secretion of organic acids.     

基于负荷聚合商模式的电网协同优化调度

在新能源在电网的渗透率增高以及柔性负荷作为调节手段出现的背景下,选取合适的调度模式,使得海量分布式的负荷资源参与电网调控,能够帮助实现削峰填谷、平滑负荷曲线等目标。基于负荷聚合商模式的协同控制结构,对包括电动汽车、空调负荷与储能设备的负荷资源进行聚合,建立了日前经济调度模型;在负荷聚合商的集群内部控制中,考虑设备的调度潜能,提出一种基于裕度指标的状态队列优先算法,实现部分负荷优先响应。最后,仿真算例得出了负荷聚合商参与电力系统的日前协同调度运行计划,验证了优化方法以及调控策略的可行性。     

Dual-band reflective polarization converter based on metasurface

In this paper, a dual-band and reflective polarization converter based on metasurface is proposed. Its unit cell is composed of two layers of metal plates separated by a dielectric substrate. The simulation results show that the proposed converter is able to convert x- or y-polarized incident waves into cross-polarized waves perfectly in frequency bands of 6.75—10.59 GHz and 17.78—19.61 GHz, and the polarization conversion ratio (PCR) is nearly 100%, which can also convert linearly polarized waves into circularly polarized waves at four frequencies. It can be widely used in applications of radar satellites, antenna design and telecommunication with the function of realizing polarization conversion in two bands and achieving high PCR simultaneously.     

基于一致性算法的直流受端电网分布式调频资源协同频率控制

直流受端电网中大容量直流功率的馈入和大量分布式光伏及储能经电力电子变换器接入,导致受端电网同步机电源逐渐被取代,系统等效惯量下降,严重影响了受端电网的频率特性。因此,挖掘电网调频资源、增加电网频率控制的灵活性十分重要。针对上述问题,基于一致性算法,提出了利用受端电网中配电网的分布式调频资源,包括分布式光伏、储能、柔性负荷等协同参与电网一次调频的分布式控制方法。该控制方法能够有效应对由于调频资源数量大而导致的计算难度增大问题,并可通过定时刷新分布式调频资源的运行状态并自适应计算频率响应系数,实现在故障发生时快速响应频率变化。通过对等效直流受端电网中配电网调频资源以不同控制策略参与频率调节的仿真对比分析,验证了文中方法对直流受端电网频率调节的有效性及经济性。     

浅析中国国家博物馆与首都博物馆的设计特点

通过比较分析中国国家博物馆与首都博物馆设计特点,从历史文化、空间形态、传统与现代科技结合等几个方面探讨大型博物馆的创新设计理念和设计方法。     

F级燃气—蒸汽联合循环余热锅炉化学清洗关键技术

主要阐述了F级燃气—蒸汽联合循环余热锅炉化学清洗的关键点及关键控制技术,以工程实例介绍燃气—蒸汽联合循环余热锅炉化学清洗工艺,并对全面实现化学清洗自动化控制进行了展望。     

超声振动辅助切削SiCp/Al复合材料的加工机理及试验

切削加工过程中材料损伤形式对加工表面质量会产生较大影响,现有仿真分析难以模拟真实颗粒失效行为,通过建立二维微观多相有限元模型能够深入了解材料损伤与表面质量的关系。基于常规切削（Conventional cutting,CC）与超声振动辅助切削（Ultrasonic vibration-assisted cutting,UVAC）两种加工方式,通过有限元仿真软件 Abaqus 对 20%SiCp / Al 复合材料的切削过程进行仿真模拟,阐释加工过程中刀具与工件的相互作用机理,并在同一参数下验证有限元仿真的准确性。通过设计单因素试验,对比两种加工方式及不同加工参数对切削力和表面粗糙度的影响规律,得出最佳加工参数组合,并对最佳加工参数下表面形貌进行分析。模拟和试验结果表明,SiC 颗粒断裂、颗粒耕犁、颗粒拔出以及 Al 基体撕裂是影响 SiCp / Al 复合材料加工质量的主要原因,刀具与颗粒不同的相对作用位置会产生不同的损伤形式。与常规切削相比,施加超声振动后可以有效抑制颗粒失效和基体损伤,使加工中的平均切削力（主切削力）降低 33%,工件已加工表面粗糙度值最大减小量为 531 nm,显著提高了表面质量。所建立的二维微观多相有限元模型,能够有效模拟铝基复合材料的加工缺陷和裂纹损伤问题, 对提高难加工材料的高质量表面制备有重要借鉴意义。