The effect of TiO2 nanotube morphological engineering and ZnS quantum dots on the water splitting reaction: A theoretical and experimental study

Ordered arrays of TiO₂ nanotubes with smooth and rippled morphologies were prepared by one-step titanium oxidation in NH₄F and ethylene glycol solution. The samples were then decorated with ZnS using a microwave-assisted solvothermal method. The experiments under constant or pulsed applied voltage resulted in smooth and rippled TiO₂material morphologies, respectively. Field emission scanning electron microscopy, incident photon-to-current efficiency, linear sweep voltammetry and electrochemical impedance spectroscopy were used to investigate the structure and morphology of the TiO₂ nanotubes, along with their photoelectrochemical activity in the water splitting reaction. An envelope function was proposed to correlate the anisotropic morphologies and broad distribution of mobility due to the random nature of charge carrier transport. The smooth and rippled morphologies were evaluated using the transmission line model. First-principles quantum mechanical calculations based on the density functional theory at the B3LYP level are conducted to obtain a better understanding of optical properties of TiO₂.     

Reinforcing cycles involving inter- and intraorganizational paradoxical tensions when managing large construction projects

In recent years, scholars have shown a growing interest in combining control and flexibility when organizing and managing large construction projects, in contrast with the traditional focus on control. Prior research recognizes that there is a paradoxical tension between control and flexibility, meaning that, while both approaches make sense individually, they appear impossible to combine. Large construction projects are interorganizational, which means that tensions between interorganizational control/flexibility coexist with tensions between intraorganizational direction/empowerment, but the interplay and possible reinforcing cycles involving the two tensions have rarely been investigated in prior research. A multiple case study of four large construction projects with three rounds of interviews show how intraorganizational direction/empowerment can influence interorganizational control/flexibility and vice versa, and demonstrate both vicious and virtuous reinforcing cycles that involve the two types of tensions. Therefore, contributing to the project management and construction management literature, it is argued that employing a systemic approach when studying interorganizational projects is essential. A systemic paradox perspective can reveal interdependencies between tensions at different organizational interfaces, improve the understanding of how individuals in all managerial positions interplay, and explain how reinforcing cycles emerge and develop; this is important to recognize when organizing, staffing and managing large construction projects.     

水电站大型竖井施工安全风险控制措施研究

竖井是大型水电工程中广泛采用的重要建筑物,但竖井的传统施工方法存在施工程序复杂、人工劳动强度大、施工效率不高等特点,同时还存在较大的安全风险。通过对杨房沟水电站大型竖井施工过程的研究,总结出精细化控制爆破、小溜渣井施工方式,同时也设计了一套用于运输的综合提升系统。采用上述创新方法不仅减少了繁琐的施工程序,降低了安全施工风险,而且大量采用机械化手段进一步提高了施工效率,确保了该工程竖井施工的安全风险可控。相关措施可为类似工程的竖井施工提供较好的借鉴作用。     

无人机控制站通用软件平台设计

针对无人机控制站难以与多型无人机互联互通的问题，从通用控制软件的角度开展研究，分析了设计需求，提出了一种采用平台+插件的软件架构，并分析了软件架构、基于XML技术的帧格式信号和参数信息描述、动态报文解析和组包、软件界面定制等关键技术。在车载控制站和便携控制站的工程验证表明，所提解决方案实现了对多型无人机的控制，具有良好的通用性、扩展性，并支持用户自定义对外通信协议和人机交互功能、界面。     

焦炉前反馈热工控制系统运行实践

焦炉生产是典型的大惯性、非线性、时变快的复杂系统，以“火落温度”为基础的焦炉前反馈热工控制系统，通过立火道温度自动测量与人工测温相关性分析、粗煤气温度测量与火落判断、标准温度的优化等运行实践，达到了自动火落时间判断、标准温度指导、加热和燃烧优化、高低温炉号判别等目的，对于稳定炉温、降低回炉煤气消耗、提高焦炭质量以及推进焦化企业技术进步具有重要意义。     

A Voltage Control Method for a Distributed Line Feeder by means of Multiagent Approach

This paper proposes a method for the coordinated control of power factor by means of a multiagent approach. The proposed multiagent system consists of two types of agent: single feeder agent (F_AG) and bus agent (B_AG). In the proposed system, an F_AG plays as an important role, which decides the power factors of all distributed generators by executing the load flow calculations repeatedly. The voltage control strategies are implemented as the class definition of Java into the system. In order to verify the performance of the proposed method, it has been applied to a typical distribution model system. The simulation results show that the system is able to control very violent fluctuation of the demands and the photovoltaic (PV) generations.     

羟基(—OH)对煤自燃侧链活性基团氧化反应特性的影响

针对煤结构及其氧化反应机理不明等问题,以羟基(—OH)和煤自燃侧链活性基团—OCH,—CHOHCH 3和—OCH 3为研究对象,采用密度泛函理论(DFT)的B3LYP-311G(d,p)方法,构建出了羟基(—OH)处于侧链活性结构邻位的小分子结构模型。基于前线轨道理论和量子化学理论,采用Gaussian 16软件对小分子模型的静电势、前线轨道的能级和电荷分布及煤氧复合反应过程中的热力学参数进行了模拟计算,探究了侧链活性基团的低温氧化特性和羟基(—OH)对其的影响。计算结果显示,在侧链活性结构中,氢原子周边呈强正电势,为亲核反应活性位点,而氧原子附近呈强负电势,为亲电反应活性位点。当羟基(—OH)处于侧链活性基团邻位时,会削弱侧链活性基团的亲电反应能力,增加—CHO和—CHOHCH 3的亲核反应能力,而使—OCH 3的亲核反应能力消失;通过分析各活性基团最高占据轨道(HOMO:Highest Occupied Molecular Orbital)和最低未占轨道(LUMO:Lowest Unoccupied Molecular Orbital)可知,侧链活性基团的稳定性与其前线轨道的成键能力并不一致,而活性基团与氧气发生复合反应的难易程度主要取决于该基团前线轨道中LUMO的成键能力,成键能力越强,复合反应越容易发生;由于羟基(—OH)改变了侧链活性基团前线轨道上的电子特性,故当其与侧链基团共存时,会使—CHO和—CHOHCH 3与氧气的复合反应更容易发生,而使—OCH 3与氧气的复合由自发的放热反应转变为非自发的吸热反应。该研究成果可为揭示煤自燃微观作用机理和研发煤自燃新型高效阻化材料提供参考。     

Adaptive fuzzy control for nontriangular form systems with time-varying full-state constraints

This article investigates an adaptive fuzzy tracking control problem for a class of nontriangular form systems with asymmetric time-varying full state constraints. Unknown functions are approximated by the fuzzy logic systems. A domination approach is employed to tackle the nontriangular form structure. Time-varying asymmetric barrier Lyapunov functions (ABLFs) are adopted to ensure full-state constraints satisfaction. Based on the backstepping technique and time-varying ABLFs, an adaptive controller is proposed and guarantees that all the signals in the closed-loop system are ultimately bounded and the time-varying full state constraints are met. Simulation examples are presented to further demonstrate the effectiveness of the proposed approach.