板坯连铸铸坯鼓肚变形的仿真研究

合理的控制影响铸坯质量的鼓肚量,有利于铸坯质量的提高。根据板坯实际生产,利用有限元法模拟凝固过程并建立二维热机耦合鼓肚模型,分析了拉速与二冷引起的蠕变时间、坯壳厚度及铸坯温度的变化对鼓肚的影响,为实际生产提供参考。     

一种新的多智能体Q学习算法

针对非确定马尔可夫环境下的多智能体系统,提出了一种新的多智能体Q学习算法.算法中通过对联合动作的统计来学习其它智能体的行为策略,并利用智能体策略向量的全概率分布保证了对联合最优动作的选择. 同时对算法的收敛性和学习性能进行了分析.该算法在多智能体系统RoboCup中的应用进一步表明了算法的有效性与泛化能力.     

Product family design and platform-based product development: a state-of-the-art review

Product family design and platform-based product development has received much attention over the last decade. This paper provides a comprehensive review of the state-of-the-art research in this field. A decision framework is introduced to reveal a holistic view of product family design and platform-based product development, encompassing both front-end and back-end issues. The review is organized according to various topics in relation to product families, including fundamental issues and definitions, product portfolio and product family positioning, platform-based product family design, manufacturing and production, as well as supply chain management. Major challenges and future research directions are also discussed.     

Carbon ion-implanted optical waveguides in Nd:YLiF4 crystal: Refractive index profiles and thermal stability

We report on the optical planar waveguides in Nd:YLiF₄ laser crystals fabricated by 6.0 MeV C³⁺ ion implantation at doses of 1 × 10¹⁵ or 2.5 × 10¹⁵ ions/cm², respectively. The refractive index profiles, which are reconstructed according to the measured dark mode spectroscopy, show that the ordinary index had a positive change in the surface region, forming non-leaky waveguide structures. The extraordinary index is with a typical barrier-shaped distribution, which may be mainly due to the nuclear energy deposition of the incident ions into the substrate. In order to investigate the thermal stability of the waveguides, the samples are annealed at temperature of 200–300 °C in air. The results show that waveguide produced by higher-dose carbon implantation remains relatively stable with post-irradiation annealing treatment at 200 °C in air.     

柳钢HK法转炉钢渣粒化系统设计及应用

总结分析了柳钢1～3号转炉HK法钢渣粒化系统的设计及运行情况。应用实践表明：采用该工艺进行钢渣处理，具有安全可靠、成品渣质量好、粒化率高、运行费用低等优点，转炉生产区环保条件及生产状况获得了改善。     

并联阻尼结构液压缓冲器冲击波形仿真

采用环形缝隙和阻尼孔并联结构的液压缓冲器,利用液体的可压缩性和活塞腔流体出流面积迅速缩小,使活塞腔压力瞬间升高,对被测试件实施冲击。建立该缓冲器的数学模型,对其冲击波形进行仿真。结果表明,环形缝隙和并联阻尼孔面积是影响冲击波形的关键因素,减小环形缝隙或并联阻尼孔面积,冲击时间缩短,冲击加速度峰值增大,调节并联阻尼孔面积,可以调节冲击波形。该缓冲器可用于跌落式冲击试验机或双波冲击试验机中,对被测试件实施较为严酷的冲击。     

艾默生共直流母线交流变频调速系统在卧螺离心机中的应用

本文对卧螺离心机差速器小轴端的调速装置采用艾默生TD2000（主变频器），艾默生TD3000（副变频器）的共直流母线交流变频技术，解决卧螺离心机背驱动电机再生能量的回收问题。并通过实例说明其节能的效果。     

Semidefinite programming relaxation approach for multiuser detection of QAM signals

A semidefinite programming (SDP) relaxation approach is proposed to solve multiuser detection problems in systems with M-ary quadrature amplitude modulation (M-QAM). In the proposed approach, the optimal M-ary maximum likelihood (ML) detection is carried out by converting the associated M-ary integer programming problem into a binary integer programming problem. Then a relaxation approach is adopted to convert the binary integer programming problem into an SDP problem. This relaxation process leads to a detector of much reduced complexity. A multistage approach is then proposed to improve the performance of the SDP relaxation based detectors. Computer simulations demonstrate that the symbol-error rate (SER) performance offered by the proposed multistage SDP relaxation based detectors outperforms that of several existing suboptimal detectors.     

5Gb/s单片集成GaAs MSM/PHEMT 850nm光接收机前端

采用0.5μm GaAs PHEMT工艺研制出了一种单片集成850nm光接收机前端,它包括金属-半导体-金属(MSM)光探测器和分布放大器.探测器光敏面积为50μm×50μm,电容为0.17pF,4V偏压下的暗电流小于17nA.分布放大器-3dB带宽接近20GHz,跨阻增益约46dBΩ;在50MHz～16GHz范围内,输入、输出电压驻波比均小于2;噪声系数在3.03～6.5 dB之间.光接收机前端在输入2.5和5Gb/s非归零伪随机二进制序列调制的光信号下,得到较为清晰的输出眼图.     

六角形空气芯光子晶体光纤的可控光子流特性

应用全矢量模型分析了六角形空气芯光子晶体光纤的传输特性,通过场图和曲线直观说明了能流和有效折射率以及有效模场面积內在的规律,有望用于制作高效率的光纤放大器,并主要讨论了随光纤结构参数(孔距)Λ和层数的改变,选择合适的参数,它的有效折射率,有效面积以及能流分布达到最大值,以此得到光纤的光子流可控特性来优化光子晶体光纤的传输性能。