基于BP神经网络的加药控制系统研究

浮选是最重要的选矿方法之一,煤矿浮选工艺自动加药控制问题是影响浮选效果的重要因素;传统加药控制主要是由加药工根据生产经验来控制,为了解决浮选精度低这一问题,文中提出采用BP神经网络作为加药控制系统加药量的预测模型,并采用动量项方法对其进行优化,通过仿真得出动量项法网络和测试样误差曲线,说明带动量项改进的神经网络更容易满足网络精度的要求,并且该方法能够有效地降低误差、减小浪费。     

Low‐voltage and high‐transmittance blue‐phase liquid‐crystal device with slanted electrodes

Abstract— A low‐voltage (～10 V_rms) and high‐transmittance (～90%) polymer‐stabilized blue‐phase liquid‐crystal (BPLC) device with a slanted‐electrodes structure is proposed. Unlike the vertical‐field‐switching (VFS) mode in which oblique incident light and a vertical field are employed, the proposed device utilizes normal incident light and an oblique field. The slanted electrodes generate a strong and uniform oblique electric field, which contributes in obtaining low voltage and high transmittance. Moreover, no couple films or prism sheets are needed, which helps to enhance the optical efficiency and simplify of the device structure. This device has great potential application for emerging BPLC displays and photonic devices.     

Linking teacher beliefs, practices and student inquiry-based learning in a CSCL environment: A tale of two teachers

The links uncovered by research connecting teacher beliefs to classroom practice and student inquiry-based learning are tenuous. This study aims at examining (a) how teacher beliefs influenced practices; and (b) how the influence on practices, in turn, impacted student inquiry learning in a CSCL environment. Through a fine-grained comparative analysis of two cases, this study explores how two teachers with different collections of beliefs enacted the same mathematics lesson on division and fractions in a CSCL environment premised on inquiry principles, and what the connections between different enactments and students’ progressive inquiry process and outcomes were. The findings suggest that the two teachers’ adherence to different beliefs led to different practices, which in turn contributed to different student learning processes and outcomes. We interpret these differences that shaped the students’ opportunities for progressive inquiry in the CSCL environment. We conclude that the teacher holding “innovation-oriented” beliefs tended to enact the lesson in patterns of inquiry-principle-based practices and technology-enhanced orchestration; these patterns interacted with each other to contribute to student inquiry learning and effective use of technology affordances.     

An efficient initialization approach of Q-learning for mobile robots

This article demonstrates that Q-learning can be accelerated by appropriately specifying initial Q-values using dynamic wave expansion neural network. In our method, the neural network has the same topography as robot work space. Each neuron corresponds to a certain discrete state. Every neuron of the network will reach an equilibrium state according to the initial environment information. The activity of the special neuron denotes the maximum cumulative reward by following the optimal policy from the corresponding state when the network is stable. Then the initial Q-values are defined as the immediate reward plus the maximum cumulative reward by following the optimal policy beginning at the succeeding state. In this way, we create a mapping between the known environment information and the initial values of Q-table based on neural network. The prior knowledge can be incorporated into the learning system, and give robots a better learning foundation. Results of experiments in a grid world problem show that neural network-based Q-learning enables a robot to acquire an optimal policy with better learning performance compared to conventional Q-learning and potential field-based Qlearning.     

Site occupations and ordering behaviour of O phase in Ti2AlNb—based intermetallics

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Facile synthesis of nitrogen and oxygen co-doped hierarchical porous carbon materials for high performance super capacitors

Journal of Porous Materials - Nitrogen and oxygen co-doped hierarchical porous carbons (NOPCs) is prepared by the pyrolysis of polyethylene glycol-200 (PEG) and triazine carbon forming agent (CFA)...     

中国观赏石文化与收藏

以推动人类文明进步发展的观念为先导,以详实的地质学、岩石学、石文化史料为切入点,介绍了我国观赏石文化的起源、发展及现状;阐述了赏石审美的本质、形式、石体标准、传统性、现代性等理论要点及其以小见大、以丑为美的审美理念。对赏石修身养性、以石陶情及赏石文化与道教情结的学术价值进行了评述;对从古至今的中华文化名人为赏石理论的创立、鉴赏、收藏和发展作出的不可磨灭的历史贡献进行了评价。     

The electrochemical synthesis of aminonitriles I. H-cell studies with adiponitrile and azelanitrile

Adiponitrile and azelanitrile were electrochemically hydrogenated to their corresponding aminonitriles in a divided H-cell using Raney nickel powder as the cathode material. The effects of current, temperature, and solvent/supporting electrolyte composition on product selectivities were investigated. Syntheses of the fully hydrogenated diamine by-product increased with increasing current and solution temperature. When a 0.8 M adiponitrile/alcohol/water/ammonium actetate electrolyte was hydrogenated at temperatures of 35–45°C, 6-aminocapronitrile selectivities in the range of 79–97% and current efficiencies of 50–60% were obtained. The optimum applied current was 60 mA for each 2.5 g of catalyst (an apparent current density of 4.8 mA cm^–2). For the case of azelanitrile, reaction selectivities for the partially hydrogenated 9-aminononanenitrile product ranged from 80–93%.