微晶纤维素在稀硫酸中的热解机制研究

以微晶纤维素为原料,通过热转化可以得到葡萄糖、乙酰丙酸等多种用途广泛的有机化合物,在此过程中也存在脱水碳化竞争反应,得到生物碳副产物.分别以酸浓度和温度为实验变量,采用高效液相色谱(HPLC)对样品的液体产物进行表征,探索微晶纤维素在稀硫酸溶液中的热分解转化机制.结果表明:微晶纤维素的热分解转化是连续反应和竞争反应同时存在的复杂反应过程;控制温度在180～200℃,酸浓度在0.05～0.1 mol/L时,可获得最大产率的葡萄糖(约21.90％);若温度为200℃,酸浓度为0.2 mol/L时,则主要产物为乙酰丙酸.     

基于PCC-RBF网络的风电功率短期预测方法

风电功率预测对风电场安全平稳运行、电网调度具有重要意义。针对风电功率短期预测指标选择不合理、预测精确度偏低的问题,提出一种基于皮尔逊相关系数(PCC)和径向基函数(RBF)神经网络的风电功率短期预测方法。该方法利用PCC筛选出与风电功率密切相关的3个指标,即电流、温度、风速,然后以这3个指标作为预测模型的输入对风电功率进行RBF样本训练与短期预测。试验结果表明,所提的预测模型预测误差更小,预测精度更高,能够满足风电功率短期预测的要求,具有广泛的应用前景。     

一起220kV母线保护动作案例分析与讨论

近年来,随着电网技术的发展和继电保护装置的不断更迭,母线保护在运行中出现了一些新问题.介绍了某220 kV变电站内发生的一起因压板投入不正确导致的220 kV母线保护延时跳闸的事故案例,总结了母联开关跳位与母线分列压板两者的逻辑关系以及对母线保护的影响,并针对不同的逻辑关系提出了不同运行方式下母联开关和分列压板的正确操作顺序.     

整流板对T型分流三通管局部阻力特性影响的数值研究

三通管的阻力特性对管网系统的流量分配及经济输送有着显著影响。以某电厂热一次风管道中的T型分流三通管为研究对象,采用Fluent软件对安装整流板后的三通管道进行数值模拟,分析不同形式整流板对三通管内流体阻力特性的影响,并通过能量耗散分布分析了整流板的减阻机理。模拟结果表明:安装整流板后,侧支管局部阻力系数ζ01明显减小,其中基于流场特征确定的方案3减阻效果最好;整流板高度对ζ01影响较大,当流量比q较小时,ζ01随整流板高径比h增加而减小;q较大时,随h增加,ζ01先减小后增加,其中h=0.38时减阻率最大,为40.6%;整流板长度对ζ01影响较小,q较小时,ζ01随整流板长径比l的增加小幅度降低;q=0.6时,随l增加,局部阻力系数先减小然后趋于不变,其中l=3.13时减阻率最大,为40.2%;q较大时,随l增加,ζ01略微增大。     

Synergistic Flame Retardant Effects of Carbon Nanotube-Based Multilayer Nanocoatings

In an effort to develop highly functionalized flame retardant materials, hybrid nanocoatings are prepared by alternately depositing a positively charged polyaniline (PANi) and negatively charged montmorillonite (MMT) using the layer-by-layer (LbL) assembly technique. Carbon nanotubes (CNTs) are employed in polymer nanocomposites as effective reinforcement, where nanotubes are stabilized in MMT aqueous solution. The 3D structure and high density of CNTs deposited in the PANi/CNTs-MMT multilayers produce thicker and heavier coatings in comparison to the LbL assemblies without CNTs. Vertical and horizontal flame testing show that the incorporation of CNTs improves fire resistance. Additionally, cone calorimetry reveals that stacking two nanomaterials (MMT and CNTs) in a single coating shows a significant reduction in peak heat release rate (up to 51%), total smoke release (up to 47%), and total heat release (up to 37%) for the polyurethane foam. The enhancement of flame retardancy is attributed to a synergistic effect; MMT serves as a physical barrier that retards the diffusion of heat and gas. The addition of CNTs strengthens the thermal stability and high char yield. These results, coupled with the simplicity with which the LbL deposition is applied, present a viable alternative to halogen-free flame retardant nanocoatings to natural and synthetic fibers.     

Natural Polysaccharides as Multifunctional Components for One-Step 3D Printing Tough Hydrogels

Natural polysaccharides (NPS) are regarded as biomolecular and structural components for preparing high-performance tough hydrogels. But the one-step fabrication of NPS-containing hydrogels in seconds and the template-free design of complicated high-resolution structures are still significant challenges in this field. To meet these requirements, various NPS-containing tough hydrogels are fabricated and processed into 2D/3D structures via the combination of Ru(bpy)₃²⁺-mediated photochemistry and extrusion 3D printing technique. The whole fabrication process is one-step, completed in tens of seconds under visible light irradiation. It is found that the used NPS plays a key role in achieving the fabrication of high-performance structured tough hydrogels. The high reactivity of functional groups in the used NPS can shorten their gelation times. Long rigid chains of the used NPS, their hierarchical assemblies, and contrasting multinetworks benefit from the efficient dissipation of mechanical energy and enhancement of its operational stability. Strong supramolecular interactions enable hydrogel precursors to have high viscosities, therefore providing good controllability to design high-resolution and complicated tough hydrogel structures via extrusion 3D printing. It is anticipated that this straightforward fabrication strategy and findings will open new horizons for NPS-containing materials.     

脉内无固废精准开采采矿方法在嵩县山金的应用

嵩县山金北翼矿体走向长度短、平均厚度薄、矿体倾角小、地质品位低、岩石稳固性较差,采用盘区机械化上向水平分层进路充填采矿法开采,采切工程投入大,成本费用高,安全投入及风险更大。针对该类矿体,提出了一种脉内无固废精准开采采矿方法,通过构筑人工假巷形成运输条件,人工架设钢溜井形成行人、放矿、通风、泄水条件,采矿工作完成后通过脉内悬吊1 m³铲运机完成机械化出矿及设备换层工作,采用分层充填采矿法充填采空区,提高回采效率。与原采矿方法进行技术经济对比,采用脉内无固废精准开采采矿方法经济效益更好,不需要布置分段巷、采场联巷等掘进工程,在工程投入方面可节约23.2万元,不产生掘进废石,实现了脉内无固废开采的目的。现场试验结果表明：该开采方法具有开采精度高、采（出）矿效率高、采矿损失贫化低、安全投入小、经济效益高等优点,推广前景较大。     

炼厂硫腐蚀的典型案例分析及解决措施

通过硫在不同温度与环境下对金属材料腐蚀的典型案例分析，简述其腐蚀机理与解决,工对今后炼厂高硫油加工提出进一步建议。     

THE STRUCTURE CONTROL OF ALUMINUM FOAMS PRODUCED BY POWDER COMPACTED FOAMING PROCESS

A new technique, powder compact foaming process for the production of aluminum foams has been studied in this article. According to this method, the aluminum powder is mixed with a powder foaming agent (Till2). Subsequent to mixing, the powder blend is hot compacted to obtain a dense semi-finished product. Upon heating to temperatures within the range of the melting point, the foaming agent decomposes to evolve gas and the semi-finished product expands into a porous cellular aluminum. Foaming process is the key in this method. Based on experiments, the foaming characteristics were mainly analyzed and discussed. Experiments show that the aluminum-foam with closed pores and a uniform cell structure of high porosity can be obtained using this method by adjusting the foaming parameters: the content of foaming agent and foaming temperature.     

WZ型系列真空铝钎焊炉的研制

简要介绍了WZ型系列真空铝钎焊炉型号，规格等技术参数，并以WZLQH－30型真空铝钎焊炉为例介绍了真空铝钎焊炉的结构及其特点，总结了真空铝钎焊炉设计研究及调试过程中的一些经验体会。