Novel organic dyes containing N-bridged oligothiophene coplanar cores for dye-sensitized solar cells

Three novel organic dyes adopting fully-fused coplanar heteroarene as the donor moieties end-capped with two cyanoacrylic acids as acceptors and anchoring groups have been synthesized, characterized, and used as the sensitizers for dye-sensitized solar cells (DSSCs). The photophysical and electrochemical properties of the novel dyes and the characteristics of the DSSCs based on the novel organic dyes were investigated. The incorporation of the coplanar cores with electron-donating N-bridges are beneficial for the better intramolecular charge transfer (ICT), giving these new dyes good light-harvesting capability. The LUMO energy levels of these coplanar heteroacene-based dyes are sufficiently high for the efficient electron injection to TiO₂ upon photo-excitation, while the suitable HOMOs allow the regeneration of oxidized dyes with the electrolyte redox (I⁻/I₃⁻). The structural features of the coplanar cores (penta vs. hexa heteroarene) as well as the alkyl substitutions play crucial roles in governing the physical properties and device performance. Among these three novel organic sensitizers, the EHTt dye composed of a fully fused hexa-arene core and less bulky N-alkyl groups caused the DSSC to show the best photovoltaic performance with an open-circuit voltage (V_OC) of 0.58 V, a short-circuit photocurrent density (J_SC) of 13.72 mA/cm², and a fill factor (FF) of 0.69, yielding an overall power conversion efficiency (PCE) of 5.52% under AM 1.5G solar irradiation.     

Characterization of sea water ageing effects on mechanical properties of carbon/epoxy composites for tidal turbine blades

In recent years, many tidal turbine projects have been developed using composites blades. Tidal turbine blades are subject to ocean forces and sea water aggressions, and the reliability of these components is crucial to the profitability of ocean energy recovery systems. The majority of tidal turbine developers have preferred carbon/epoxy blades, so there is a need to understand how prolonged immersion in the ocean affects these composites. In this study the long term behaviour of different carbon/epoxy composites has been studied using accelerated ageing tests. A significant reduction of composite strengths has been observed after saturation of water in the material. For longer immersions only small further changes in these properties occur. No significant changes have been observed for moduli nor for composite toughness. The effect of sea water ageing on damage thresholds and kinetics has been studied and modelled. After saturation, the damage threshold is modified while kinetics of damage development remain the same.     

Mathematical representation of radiality constraint in distribution system reconfiguration problem

Distribution systems are most commonly operated in a radial configuration for a number of reasons. In order to impose radiality constraint in the optimal network reconfiguration problem, an efficient algorithm is introduced in this paper based on graph theory. The paper shows that the normally followed methods of imposing radiality constraint within a mixed-integer programming formulation of the reconfiguration problem may not be sufficient. The minimum-loss network reconfiguration problem is formulated using different ways to impose radiality constraint. It is shown, through simulations, that the formulated problem using the proposed method for representing radiality constraint can be solved more efficiently, as opposed to the previously proposed formulations. This results in up to 30% reduction in CPU time for the test systems used in this study.     

Φ177mm PQF无缝管连轧机前横移系统改进

对鞍钢股份无缝钢管厂连轧机前毛管坯横移装置存在的设计缺陷进行了分析,并提出改进方案,将原横移装置由高架轨道横移机构及上下升降链传动装置,改进为地面轨道横移系统及同步旋转臂实现取管、放管过程。实施后消除了生产故障,缩短了轧制周期,降低生产成本。     

仙游抽水蓄能电站尾水系统充排水试验

为检查工程质量,查找输水系统可能存在的问题并消除隐患,保障电站安全运行,福建仙游抽水蓄能电站在投产发电前,要对输水发电系统进行充水试验与放空排水试验,在试验过程中监测输水系统的应力、应变与渗漏水情况。本文以尾水系统为例,介绍了试验所应具备的工程条件、工作程序及技术要求、试验成果分析和存在问题处理等。试验表明,仙游抽水蓄能电站尾水系统设计合理,施工质量优良,结构可靠,可供同类工程参考与借鉴。     

TCBR-HMM: An HMM-based text classifier with a CBR system

This paper presents an innovative solution to model distributed adaptive systems in biomedical environments. We present an original TCBR-HMM (Text Case Based Reasoning-Hidden Markov Model) for biomedical text classification based on document content. The main goal is to propose a more effective classifier than current methods in this environment where the model needs to be adapted to new documents in an iterative learning frame. To demonstrate its achievement, we include a set of experiments, which have been performed on OSHUMED corpus. Our classifier is compared with Naive Bayes and SVM techniques, commonly used in text classification tasks. The results suggest that the TCBR-HMM Model is indeed more suitable for document classification. The model is empirically and statistically comparable to the SVM classifier and outperforms it in terms of time efficiency.     

Adaptive robust boundary control of shaft vibrations under perturbations with unknown upper bounds

This paper presents robust and adaptive boundary control designs to stabilize the two‐dimensional vibration of hybrid shaft model. The hybrid shaft is mathematically represented by a set of partial differential equations, governing the shaft vibrations, coupled to ordinary differential equations, describing rigid body spinning and dynamic boundary conditions. The control objective is to stabilize the transverse vibrations of the perturbed shaft while regulating the spinning rate. To achieve this, the paper first establishes robust boundary control laws that fulfil the control objective in the presence of modeling uncertainties and external disturbances operating over the shaft domain and boundary. Lyapunov‐based analyses show that the proposed robust control exponentially stabilizes the shaft with vanishing distributive perturbations, while assuring ultimately bounded vibrations in the case of nonvanishing perturbations. Then, adaptive control philosophy is utilized to achieve redesigned robust controllers that only use online adaptation of control gains without acquiring the knowledge of bounds on perturbations, as well as dynamic parameters. An advantage of this design is avoiding an overconservative robust control law, which may induce poor stability and chattering in tackling system perturbations with unknown upper bounds. Simulations through finite element method illustrate the results. Copyright © 2014 John Wiley & Sons, Ltd.     

Simplified anode architecture for PEMFC systems based on alternative fuel feeding: Experimental characterization and optimization for automotive applications

The need to reduce PEMFC systems cost as well as to increase their durability is crucial for their integration in various applications and especially for transport applications. A new simplified architecture of the anode circuit called Alternating Fuel Feeding (AFF) offers to reduce the development costs. Requiring a new stack concept, it combines the simplicity of Dead-End Anode (DEA) with the operation advantages of the hydrogen recirculation. The three architectures (DEA, recirculation and AFF) are compared in terms of performance on a 5-kW test bench in automotive conditions, through a sensitivity analysis. A gain of 17% on the system efficiency is observed when switching from DEA to AFF. Moreover, similar performances are obtained both for AFF and for recirculation after an accurate optimization of the AFF tuning parameters. Based on DoE data, a gain of 25% on the weight of the anodic line has been identified compared to pulsed ejector architecture and 43% with the classic recirculation architecture with blower only (Miraï).     

高瓦斯突出矿井底抽巷一巷多用技术研究与实践

胡底煤业为高瓦斯高突出高矿压的三高矿井。对高瓦斯高突出的治理，该矿采用“地面网络预抽、区域模块降量、底抽穿层保掘、高位顺层保采”的四级模式，施工底抽巷，实现“底抽穿层消突、区域模块降量、异巷探测增效、多巷通风治患、循环排矸减压”等“一巷多用”。该4种方法已在1303（上）、1305（上）工作面应用并推广，取得了良好的效果，大大提高了掘进效率且满足抽放、探放水、通风需要；回填矸石初步设计现已经完善，待下一步掘进将实现填矸作用。     

Sustainability of ride-hailing services in China’s mobility market: A simulation model of socio-technical system transition

As a symbol of sharing economy, ride-hailing services have spread to Asia, where various forms of services have been established according to the existing socio-technical regimes, including legal, policy, and environmental concerns. China, in particular, has accepted ride-hailing services by revising existing institutions. This study analyzes China’s acceptance of ride-hailing services in the socio-technical system context set up for legacy services. Simulation modeling, combined with transition theory and an agent-based model, is used to analyze the data. This study calculates consumer disutility based on mobility market share, reflecting consumer preference, and predicts the sustainability of ride-hailing services. The simulation results conclude that legalization and socio-technical context are of importance for sustainable mobility.