关于计算机领域创新教育的实践及探索

本文分析了创新教育与素质教育的关系,从营造教学氛围、转变教育眼光、拓展学习平台等方面提出了对创新教育的思考,并以优化教学环境、转变教学方式;以实训课和作业相结合为平台;以举办各种形式的讲座来激发学生的创新灵感等为素质教育夯实了基础。     

基于定点ICA算法的人脸识别方法

提出定点ICA算法结合均一化欧氏距离的人脸识别方法。该方法不仅可以提取出独立主成分，而且收敛速度快，克服了PCA算法提取特征不独立和一般ICA算法收敛速度慢的缺点。在特征聚类方法中，均一化欧氏距离的聚类效果优于欧氏距离和马氏距离。在正交在预处理程中，投影特征空间维数的选取根据具体数据库和训练样本集通过试验确定。试验结果表明，该人脸识别方法具有较好的识别能力和鲁棒性。     

Graphene‐Armored Aluminum Foil with Enhanced Anticorrosion Performance as Current Collectors for Lithium‐Ion Battery

Aluminum (Al) foil, as the most accepted cathode current collector for lithium‐ion batteries (LIBs), is susceptible to local anodic corrosions during long‐term operations. Such corrosions could lead to the deterioration or even premature failure of the batteries and are generally believed to be a bottleneck for next‐generation 5 V LIBs. Here, it is demonstrated that Al foil armored by conformal graphene coating exhibits significantly reinforced anodic corrosion resistance in both LiPF₆ and lithium bis(trifluoromethanesulphonyl) imide (LiTFSI) based electrolytes. Moreover, LiMn₂O₄ cells using graphene‐armored Al foil as current collectors (LMO/GA) demonstrate enhanced electrochemical performance in comparison with those using pristine Al foil (LMO/PA). The long‐term discharge capacity retention of LMO/GA cell after ≈950 h straight operations at low rate (0.5 C) reaches up to 91%, remarkably superior to LMO/PA cell (75%). The self‐discharge propensity of LMO/GA is clearly relieved and the rate/power performance is also improved with graphene mediations. This work not only contributes to the long‐term stable operations of LIBs but also might catalyze the deployment of 5 V LIBs in the future.     

基于多因子粒子群的高维数据特征选择算法

特征选择是机器学习和数据挖掘领域中一项重要的数据预处理技术,它旨在最大化分类任务的精度和最小化最优子集特征个数。运用粒子群算法在高维数据集中寻找最优子集面临着陷入局部最优和计算代价昂贵的问题,导致分类精度下降。针对此问题,提出了基于多因子粒子群算法的高维数据特征选择算法。引入了进化多任务的算法框架,提出了一种两任务模型生成的策略,通过任务间的知识迁移加强种群交流,提高种群多样性以改善易陷入局部最优的缺陷;设计了基于稀疏表示的初始化策略,在算法初始阶段设计具有稀疏表示的初始解,降低了种群在趋向最优解集时的计算开销。在6个公开医学高维数据集上的实验结果表明,所提算法能够有效实现分类任务且得到较好的精度。     

Performance improvement for source mobility in named data networking based on global–local FIB updates

The mobile devices have become the norm, rather than an exception for people’s daily life, and these devices possess strong ability (e.g., increasingly large storage) to serve as content sources in future information-centric networks, e.g., named data networking (NDN). The efficient discovery of contents provided by mobile devices is a challenging task. Most of existing studies adopted ID-Locator split architecture to handle the problems raised by source mobility in NDN, e.g., the content source is suddenly disconnected from the network when providing on-going services. However, these solutions require very high control overhead to maintain up-to-date location information of sources in an ID-Locator mapping system. Software defined networking (SDN) is a promising tool to make cross-layer decisions based on its logically centralized controller, and thus can facilitate the implementation of forwarding strategies in NDN according to application requirements. To this end, this paper proposes a new packet forwarding algorithm under SDN paradigm that is able to update the forwarding information base (FIB) of NDN node considering both the mobility pattern of mobile sources and network states. In particular, the algorithm leverages the SDN controller to perform the tradeoff between global FIB updates on all NDN nodes and local FIB updates on NDN nodes that are previously connected by mobile sources to lower the control overhead. A discrete-event simulator based on NS3 simulation framework is developed to validate the effectiveness and feasibility of the proposed algorithm. In addition, the performance of the algorithm is compared with that of existing solutions based on ID-Locator split architecture. The results show that the proposed packet forwarding algorithm has a lower request-to-response latency and higher successful content request ratio with reduced control overhead under different working conditions.     

给水立管的抗低温性能试验分析

为了保障给水管网立管在寒潮中的安全,进一步提高给水管网立管的安装及使用质量.试验模拟严寒天气状况下,通过改变管道材质、管道新旧以及保温棉厚度3个变量因素的情况下,根据立管管内水温下降至0℃所需的时间,从而分析立管的抗低温性能.结果表明:不锈钢管的抗低温性能最好.因此,管道的选材需结合实际情况来优化;包裹保温棉厚度越厚的立管抗低温性能越好,包裹40 mm厚度的保温棉的立管的抗低温性能最高能提升6.6倍,采取有效的安装和保温等防冻裂措施具有必要性;且新旧管道的防冻需一并重视,才能达到安全稳定供水的目的.     

一种快速检测遥感图像中机场跑道的方法

本文在分析机场跑道结构特征的基础上，提出了一种从高分辨率遥感图中检测机场跑道的方法。具体介绍了嵌入置信度的边缘检测算法和基于线基元的直线提取方法，前者增加了检测结果的可靠性，后者加快了跑道检测速度。最后的实验结果表明本文算法是快速、稳健的。     

基于拥塞控制的DDoS防御机制的研究

DDoS攻击数据流在发生网络拥塞的情况下并不降低他们的发送速率,充满了路由器的缓冲区,剥夺其他正常数据流的带宽。基于这一网络行为,从拥塞控制的角度来研究DDoS攻击目标端的防御机制。通过仿真实验,对传统的队列管理策略和基于聚类的拥塞控制机制ACC进行了比较,进一步验证了ACC算法在控制恶意数据流的有效性。     

Microstructure and electrical properties of (1 − x)K0.5Na0.5NbO3–x(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 lead-free piezoelectric ceramics

The (1 ? x)K_0.5Na_0.5NbO₃ ? x(Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃ (KNN–BCTZ) lead-free ceramics were fabricated by conventional solid-state sintering technique. The microstructure and electrical properties of the ceramics were investigated. The X-ray diffraction analysis revealed that the ceramics formed a single phase perovskite solid solutions with the symmetry of orthorhombic at x < 0.03. The crystal phase of the ceramics changed from orthorhombic phase to pseudocubic phase when x > 0.04. The coexistence of orthorhombic and pseudocubic (tetragonal) phases was observed near room temperature when 0.03 ≤ x ≤ 0.04. The grains grew up obviously when 2 mol% BCTZ was added, but the grain size was found to reduce gradually with further increasing BCTZ content. The T _C and T _O-T decreased with the increasing BCTZ content. The ferroelectric and piezoelectric properties were abruptly degraded as x ≥ 0.05. Optimum properties (d ₃₃ = 136 pC/N, k _p = 27 %, k _t = 26.5 %, Q _m = 25, P _r = 14.67 μC/cm², E _c = 11.23 kV/cm, T _C = 347 °C, $\varepsilon_{33}^{\text{T}} /\varepsilon_{0} = 8 6 1. 5$ ε 33 T / ε 0 = 8 6 1.5 , tan δ = 0.04) were obtained for the ceramica with x = 0.03.     

酶解法催化鹅油制备甘油二酯的研究

为提高鹅油的附加值,开发天然食品添加剂,本试验以肥肝鹅腹脂精炼后的鹅油为脂肪酸供体制备甘油二酯。以鹅油混合脂肪酸、甘油为原料,甘油二酯的生成率为指标,底物比(脂肪酸∶甘油)、加酶量、反应时间及反应温度为因素,采用响应面法对鹅油甘油二酯的制备工艺进行了优化。结果表明:反应温度为46℃,反应时间为9.2 h,底物比为1.2,加酶量为3.03%时,甘油二酯的生成率为92.57%。