摘要： 第1节 化学变化的特征 中考重点难点 1.物理变化与化学变化 (1)没有生成新物质的变化叫作物理变化,有新物质生成的变化叫作化学变化. (2)在物理变化中,改变的一般是物质的状态(固态、液态、气态)或形状.在化学变化中,物质的种类发生了改变.需要注意的是,石油分馏属于物理变化,煤的干馏属于化学变化,燃烧引起的爆炸属于化学变化,而气球爆炸、轮胎爆炸属于物理变化.

关键词： “三新”   高中化学   提质增效  

摘要： 随着新课程、新高考、新教材的实施,高中化学教学面临着质量提升与效率优化的双重挑战。本文章围绕“三新”背景下的高中化学提质增效,深入分析了高中化学教学的现状,并提出了四条具有实际可操作性的策略:优化教学设计、深化学科融合、借助信息技术构建智慧化课堂、注重个性化教学以满足不同层次学生的需求。通过这些策略的实施,推动了学生核心素养的发展,促进了教学质量与效率的同步提升,为高中化学教学工作改进提供了有效参考。

关键词： HSE监理   布袋除尘器   可燃气体   检维修作业  

摘要： 中卫市人民政府网站公布了宁夏某化工公司“12·02”事故调查报告。根据报告,事故的直接原因是:进入造气车间燃烧炉未完全燃烧的可燃气体进入布袋除尘器内聚集并达到爆炸极限,在没有将布袋除尘器箱体及有关管道内可燃气体置换完全的情况下,违章检维修作业,造成气体闪爆,导致事故发生。

关键词： Pyrolysis  

摘要： The study of the lignin pyrolysis mechanism is an important precondition for the efficient prepara⁃ tion of liquid fuels,carbon materials,chemicals,and other high⁃value products. Recent advances in lignin py⁃ rolysis mechanisms revealed through computational chemistry methods including molecular dynamics simula⁃ tion and quantum chemistry calculation were reviewed. Firstly,the structural characteristics of lignin were in⁃ troduced and the typical lignin model compounds used in computational chemistry were expounded. Subse⁃ quently,based on the molecular dynamics simulation and quantum chemistry calculation of the lignin pyrolysis mechanism,the overall evolution behavior of lignin in the pyrolysis processes,C—O and C—C linkage cleav⁃ age between lignin monomers,conversion of lignin monomer,and interactions of products during lignin py⁃ rolysis were discussed. Finally,the existing problems in the study of the lignin pyrolysis mechanism and the direction worthy of the further study were expounded to provide a reference for the high⁃value utilization of bio⁃ mass in the future. © 2025 Southeast University. All rights reserved.

关键词： Modal analysis  

摘要： Single-inductor multi-port (SIMP) converters have great application potential due to their "more silicon less magnetic" feature. However, there are so many switching modes of SIMP converters that the modulation strategy design is complicated. At present, the design of the modulation strategy is mainly to manually select the switching mode sequence and carry out modal analysis, which requires professional knowledge of power electronics. This research proposes a reinforcement learning (RL) based modulation strategy design technique for SIMP converters. The proposed method uses a neural network (NN) to produce modulation strategies, takes known conditions such as port voltages and converter structure as the input of the NN and leverages a set of basic principles to provide rewards for training the NN, avoiding complex artificial design. With RL, the NN sums up experience during trial-and-error without human intervention, and finally generates the optimal modulation strategy under different operating conditions. Based on this method, modulation strategies are designed for a SIMP converter and the effectiveness of the method is verified by experiments. © 2025 Beijing University of Aeronautics and Astronautics (BUAA). All rights reserved.

关键词： Hypersonic   Thermochemical non-equilibrium flow   Wall temperature effect  

摘要： During the re-entry of a hypersonic aircraft into the earth's atmosphere, the surrounding air experiences dissociation, ionization, and other complex chemical phenomena due to extreme temperature by shock wave. To ensure thermal safety, the thermochemical non-equilibrium effects resulting from real-gas behavior should be taken into account. In this paper, the characteristics of a double-cone hypersonic laminar flow, including distributions of wall pressure, heat flux, and species dissociation are numerically analyzed with incoming enthalpy of 9.65-21.77 MJ/kg. The thermochemical non-equilibrium flow at different enthalpy and wall temperatures is performed with two-temperature model and Park's seven chemical reaction model. It is found that the double-cone flow features complex shock-shock interactions to form triple points. The flow topology is further brought out from the analysis of streamlines. At the lowest incoming enthalpy with isothermal wall conditions, two foci points appear. While others highlight only one focal point. As the increment of incoming enthalpy, the heat flux and dissociation of nitrogen and oxygen also increase. An increasing wall temperature leads to a larger separation bubble and a lower value of heat flux and pressure peak, while massive dissociation occurs without obvious ionization under considered cases.

摘要： 中国林业科学研究院林产化学工业研究所仪器分析中心以开展分析测试服务、分析测试技术与方法研究为主要任务.提供无机化合物分析、有机化合物的定性和结构分析、有机化合物组成定量分析、固体粉末或乳液中颗粒的粒度分布测定、微孔物质的比表面积和孔隙度测定等分析测试服务,以下大型仪器设备向社会开放共享:

摘要： 顾问 沈兆邦 余世袁 名誉主编 宋湛谦 主编 蒋剑春 副主编 储富祥 周永红 勇强 刘守新 马隆龙 肖惠宁 孙云娟(常务) 编委(以姓氏笔画为序) 于世涛(青岛科技大学) 马隆龙(东南大学) 王小慧(华南理工大学) 王成章(中国林业科学研究院) 王宗德(江西农业大学) 王春鹏(中国林业科学研究院) 王奎(中国林业科学研究院) 王挥(中南林业科技大学) 王洪学(中国石化上海石油化工研究院) 王树荣(浙江大学) 左宋林(南京林业大学) 石碧(四川大学) 史正军(西南林业大学) 付玉杰(北京林业大学) 吉兴香(齐鲁工业大学)