A general three-phase PFC controller for rectifiers with aseries-connected dual-boost topology

This paper presents a general control approach to achieve power-factor correction (PFC) for three-phase boost rectifiers with center-tapped or split DC output capacitors. These rectifiers can be decoupled into a series-connected dual-boost topology during each 60° of line cycle. A new extension of the constant-frequency one-cycle control strategy is proposed to provide the core PFC function for the dual-boost topologies. The additional logic circuits rotate the PFC functions in three phase. No multiplier is necessary to scale the current reference as required by many other approaches. Hence, this control approach is simple and general. Furthermore, the constant switching-frequency modulation is desirable for electromagnetic interference filter design and switching losses are minimized since only two high-frequency switches are controlled at any time. Simulation and experimental results are presented to verify the theoretical analysis     

水泥矿山高硫夹层处理方法实践

D水泥厂大型石灰石矿面临100万t高硫夹层处理问题,并因此而造成水泥生产硫排放超标。文章详细介绍了该矿山高硫带分布情况,提出了几种可能的处理途径并分析其可行性,最终通过优化矿山矿石搭配、微改石灰石集中取料工艺,成功处理了问题,满足了政府环保部门二氧化硫在线监测100 mg/m3的排放要求,节省了脱硫或排弃高硫料所需的高昂运行费用,同时也对自然资源做到了充分利用。     

天津乙烯装置挖潜改造

阐述了天津140kt/a乙烯装置挖潜改造的原则和目标，生产规模的确定.在“三大机组”基础不变，工艺流程改动不大，靠采用新技术挖潜力、消瓶颈、降消耗，并取得显著效果。     

超临界水中氨基乙酸的气化产氢特性

鉴于湿生物质如食品加工工业残余物和城市污泥中含有大量蛋白质的情况,以氨基乙酸作为蛋白质的模型化合物进行超临界水气化实验,研究了反应温度和反应时间耦合条件下Na₂CO₃的催化特性以及氨基乙酸气化产物特性。结果表明：添加Na₂CO₃会增大氨基乙酸的气化效率、氢气的体积分数和产率以及反应后液体化学需氧量（COD）的去除率,且添加质量分数为0.1%时的催化效果优于0.2%;Na₂CO₃主要是对H₂产率产生影响,其催化机理与已有碱性化合物的催化机理不同,可能是通过促进氨基乙酸的水解产物（甲酸）的脱羧反应来提高H₂的产率;氨基乙酸气化效率可达99.4%,生成物包括H₂、CO₂、N₂、CH₄和C₂～C₃气体,其中H₂的体积分数可超过50%,产率可达1.8 L·g^-1,且超过一半的份额来源于水,反应后液体清澈透明,COD和pH值指标均可以达到《生活杂用水水质标准》,可以进行回收利用。     

基于图结构特征分析的Top-k结构洞发现算法

结构洞通常指社交网络中处于信息扩散关键位置的节点,此类节点对社交网络舆情控制、影响力分析、信息传播等具有重要作用。为快速准确地找到社交网络中的结构洞,提出一种基于图最短路径增量的Top-k结构洞发现算法。通过计算并分析节点的图最短路径增量、连通分量个数和节点方差确定其结构洞属性值,并依据该属性值对节点进行排序,从而发现Top-k结构洞。同时,结合中介中心性算法进行节点的过滤与筛选,大幅降低算法的时间复杂度。在真实网络和不同规模LFR人工合成网络上的实验结果表明,与经典结构洞发现算法相比,该算法具有更高的结构洞检测效率。     

锁相环频率跟踪技术在等离子电源中的应用研究

近期PM2.5细颗粒雾霾造成了严峻的大气环境污染,引起了社会广泛的关注。针对此问题,研究一种新型高频高压等离子体电源去除雾霾装置,通过打断有害物质化学键的方式,从根本上起到净化空气的作用。对等离子电源负载端的稳定性进行研究,基于DSP的锁相环设计,实现对负载频率的有效跟踪,使电源工作于功率因数约为1的准谐振状态,从而大大提高系统的动态性能和稳定性能。     

Catalytic gasification of glycine and glycerol in supercritical water

Glycine and glycerol were used as the model compounds of protein and fattiness, respectively. A continuous tubular-flow reactor was used for the gasification experiments operated at 380–500 °C and 25 MPa with or without Na₂CO₃ catalyst. Compared with a negative effect on glycerol gasification, Na₂CO₃ could increase hydrogen yield and Chemical Oxygen Demand (COD) destruction efficiency, and the catalytic performance of 0.1 wt% Na₂CO₃ was better than that of 0.2 wt% for glycine gasification. When 1 wt% glycine solution with 0.1 wt% Na₂CO₃, or 1 wt% glycerol solution without Na₂CO₃ was gasified at 500 °C with the residence time of 0.98 min, their corresponding gasification efficiencies were up to 95.8% and 98%, and hydrogen yields could reach 4.14 and 5.08 mol/mol, respectively. Hydrogen molar fraction in gaseous product was about 60% and liquid effluents could be reutilized. Correspondingly, the ideal overall reaction equations for glycine and glycerol gasification were proposed.     

Unified constant-frequency integration control of three-phase standard bridge boost rectifiers with power-factor correction

In this paper, a three-phase six-switch standard boost rectifier with unity-power-factor correction is investigated. A general equation is derived that relates the input phase voltages, output DC voltage, and duty ratios of the switches in continuous conduction mode. Based on one of the solutions and using one-cycle control, a unified constant-frequency integration controller for PFC is proposed. For the standard bridge boost rectifier, a unity power factor and low total harmonic distortion can be realized in all three phases with a simple circuit that is composed of one integrator with reset along with several flips-flops, comparators, and some logic and linear components. It does not require multipliers and three-phase voltage sensors, which are required in many other control approaches. In addition, it employs constant-switching-frequency modulation that is desirable for industrial applications. The proposed control approach is simple and reliable. All findings are supported by experiments.     

投资决策风险的多特征效用评估

风险的评估和管理是投资决策的一个关键环节，以往研究，比较局限于非行为领域和大量的定性分析。在有关决策评估的某些定量化研究中，比较忽视人和组织的因素。该研究运用多特征效用理论与方法，重视人员和组织因素在风险评估中的关键作用，从而在理论上对投资决策风险及其特征作出新的界定，并运用多特征效用方法进行风险分析，构建了关于人员行为、组织管理与环境因素的风险识别模型，并进行了因素结构分析。该文还讨论了多特征效用的广泛应用前景。     

碳纤维复合材料堵漏密封加固技术在管道法兰上的应用

西气东输一线站场和线路阀室的旁通管线与干线连接的阀门全部采用法兰连接方式,由于法兰垫片存在不在正中及管线下沉而导致管道移位等因素影响已出现泄漏,存在输气生产的安全隐患。为了及时消除隐患,在不影响管道平稳运行的情况下,通过各种方法的对比分析和试验,全线采用了碳纤维复合材料堵漏密封加固技术,该方法治理法兰泄漏和法兰加固预防泄漏处理工程成本低,施工期间不需要大型设备,无须停输,免焊不动火施工风险小,采用高抗拉强度、高弹性模量碳纤维复合材料,系列化产品,湿法缠绕,现场操作灵活方便。在治理西气东输管道法兰泄漏和法兰补强上的应用取得较好效果。