Hidden Markov model-based ensemble methods for offline handwritten text line recognition

This paper investigates various ensemble methods for offline handwritten text line recognition. To obtain ensembles of recognisers, we implement bagging, random feature subspace, and language model variation methods. For the combination, the word sequences returned by the individual ensemble members are first aligned. Then a confidence-based voting strategy determines the final word sequence. A number of confidence measures based on normalised likelihoods and alternative candidates are evaluated. Experiments show that the proposed ensemble methods can improve the recognition accuracy over an optimised single reference recogniser.     

Ultra-high temperature oxidation resistance of a novel (Mo,Hf, W,Ti)Si2 ceramic coating with Nb interlayer on Ta substrate

In order to solve the challenge of recyclability of tantalum substrates in high temperature oxidation environments, a novel MoSi₂-WSi₂-HfSi₂-TiSi₂ composite ceramic coating containing an Nb interlayer was prepared on the surface of tantalum substrate by a three-step method. The mix ceramic silicide coating exhibited superior performance and effective protection for 10.2 h at 1800 °C, possibly due to the formation of an outer SiO₂-HfO₂-HfSiO₄ composite oxide film with low oxygen permeability, moderate viscosity and thermal expansion coefficient, as well as good self-healing ability. Furthermore, the coating successfully passed 537 thermal cycles from room temperature to 1800 °C. The presence of Nb interlayer significantly mitigated the thermal mismatch between the ceramic coating and the tantalum substrate, and the bidirectional diffusion of Nb element during the high temperature oxidation and thermal shock process further reduced the tendency of the coating to crack.     

Interactions of hafnia/hafnon composites with molten silicate deposits

The article examines the chemical interactions between HfO₂/HfSiO₄ composites and melts that originate from siliceous debris ingested into gas turbine engines. Pellets with hafnon volume fractions of 50%, 70% and 100% were synthesized from powders of the pure components and exposed to two types of quinary siliceous deposits (one acidic and one basic) at 1400 °C for times ranging from 10 min to 4 h. Scanning and transmission electron microscopy examinations of reacted pellets show extensive melt penetration without evidence of an effective mitigating mechanism. Acidic melts preferentially react with hafnia to form hafnon while basic melts dissolve hafnon to form hafnia; in both cases, however, the melts penetrate extensively along grain and interphase boundaries. These processes are accompanied by swelling of the reaction layer followed by blistering and exfoliation of the affected coating material. The thermodynamics of the reactions, mechanisms of melt penetration, and implications for coating applications are discussed.     

基于T—S模型的旋转式起重机稳钩保性能控制

基于T-S模型的保性能控制对控制带有不确定性系统（如旋转式起重机稳钩系统）有很好的鲁棒性,把系统可稳和保性能控制转化为解一系列矩阵不等式（LMI）的问题,得出最优的反馈矩阵,设计出基于T-S模型的最优保性能控制器,并对这种方法进行了仿真。结果表明,这种方法简单可行,并且具有很好的鲁棒性。     

深埋煤层孤岛工作面煤柱对冲击危险性的影响分析

以某矿4^-2205孤岛工作面为研究对象,结合工作面采掘实际情况,采用理论分析、数值模拟等方法,分析该工作面冲击危险性的影响因素及煤柱失稳机理,研究孤岛工作面回采过程中的煤柱应力变化及其对冲击危险性的影响。研究表明,4^-2205孤岛工作面回采过程中区段煤柱宽度逐渐减小,煤柱应力集中程度逐渐增加,破坏程度升高,煤柱逐渐由稳定状态向塑性不稳定状态变化,冲击危险性亦升高;4^-2205工作面回采至相邻采空区切眼前后位置以及顶板初次来压、周期来压及工作面“见方”时,覆岩运移破坏严重。     

New strategy to prepare nitrogen self-doped graphene nanosheets by magnesiothermic reduction and its application in lithium ion batteries

Nitrogen self-doped graphene (N/G) nanosheets were prepared through magnesiothermic reduction of melamine. The obtained N/G features porous structure consisting of multi-layer nanosheets. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectra and X-ray diffraction (XRD). As anode of lithium ion batteries (LIBs), it exhibits excellent reversible specific capacity of 1753 mAh g⁻¹ at 0.1 A g^-1 after 200 cycles. The reversible capacity can maintain at 1322 mAh g⁻¹ after 500 cycles at 2 A g⁻¹. At the same time, all results indicate remarkable cycle stability and rate performance as anode materials. Furthermore, this study demonstrates an economical, clean and facile strategy to synthesize N/G nanosheets from cheap chemicals with excellent electrochemical performance in LIBs.     

纤维素/碳纳米管复合纤维的制备及其功能化应用

针对导电材料填充纤维素复合纤维的强度与导电性能难以兼顾的问题,利用羧基改性碳纳米管能较好地分散在水中,以及低温(-10℃)条件下氢氧化钠/尿素溶液能较好地溶解纤维素这个特性,制备了纤维素/碳纳米管复合纺丝液,然后通过湿法纺丝制备了含有不同质量分数碳纳米管的复合纤维,对复合纤维的微观结构、力学性能以及电学性能进行表征。结果表明：由于纤维素与碳纳米管之间的强相互作用以及碳纳米管的取向,使复合纤维具有良好的力学性能和导电性能,当碳纳米管质量分数为20%时,复合纤维的断裂强度为165 MPa,电阻为3 kΩ;当电压升高到30 V时,复合纤维的温度在15 s内可上升到62.3℃,且吹气和浸入水中都能产生规律的电阻变化。     

ZnxCd（1-x）S/TiO2异质结复合纤维的制备及其光催化性能

通过静电纺丝和水热法联用成功制备了ZnxCd1-xS/TiO2纳米纤维。利用XRD、SEM、UV-vis、EDS、BET等分析测试手段对样品的结构、光学性能及形貌进行表征。用罗丹明B(RB)模拟有机污染物进行了光催化降解实验。结果表明,在TiO2纳米纤维上长了一层致密地ZnxCd1-xS颗粒,形成了ZnxCd1 xS/TiO2异质结复合纤维,且其光谱响应范围拓宽至可见光区,与纯TiO2纳米纤维相比,可见光催化活性明显提高。当水热时间为24 h时,ZnxCd1-xS/TiO2复合纤维的光催化活性最高,RB溶液在可见光下降解1 h,脱色率达到90.87%,并且该样品易于分离、回收和再利用。     

Gel properties of collagens from skins of cod (Gadus morhua) and hake (Merluccius merluccius) and their modification by the coenhancers magnesium sulphate,glycerol and transglutaminase

The gel properties of two different kinds of fish gelatins prepared from cod (Gadus morhua) and hake (Merluccius merluccius) and modified by the coenhancers glycerol, salt and microbial transglutaminase, were examined. Gel strength was substantially increased by the addition of coenhancers although results varied, depending on the species. In gelatin from hake (M. merluccius) skin, the highest values were obtained with 10 mg/g of transglutaminase, whereas magnesium sulphate was more effective at both concentrations (0.1 and 0.5 M) in gelatin from cod (G. morhua) skin. Although, in both gelatins, the addition of any ingredient increased the viscosity modulus (G″), the elastic modulus (G′) was only increased by the addition of glycerol 15% (w/v) and MgSO₄ 0.5 M in hake (M. merluccius) gelatins; in cod (G. morhua) it was increased by all ingredients. The gelling and melting points, very important properties in fish gelatin, showed a notable improvement, the behaviour being different, depending on the species.     

Performance of unit PEM fuel cells with a leaf-vein-simulating flow field-patterned bipolar plate

This study was conducted to investigate the performance of 25-cm²-unit polymer electrolyte fuel cells, the bipolar plate of which has a flow field that simulates leaf veins. The test flow fields were serpentine, parallel, and net leaf flow fields mimicking ginkgo and dicotyledonous leaves. The maximum power density for the ginkgo flow field was 7% lower than that for the serpentine flow field, and 40% higher than that for the parallel flow field under normal operating conditions. However, the air-feeding power required by the ginkgo was only 3% of that required by the serpentine. The usable power density for the ginkgo flow field was the highest among all flow fields. Additionally, the water-removal capability of the ginkgo flow field was superior to that of the parallel and net leaf flow fields, but inferior to that of the serpentine flow field. Furthermore, the amount of water remaining in the flow field channels was found to be correlated to the length of the unit channel. Therefore, the ginkgo pattern can be considered to be an optimal flow field design for the fuel cell.