Preparation and flocculation properties of biodegradable konjac glucomannan-grafted poly(trimethyl allyl ammonium chloride)

Polymer Bulletin - Preparation of konjac glucomannan-grafted poly(trimethyl allyl ammonium chloride) (KGM-g-PTMAAC) was carried out using KGM as polysaccharide matrix and TMAAC as cationic...     

物联网中基于KNN和BP神经网络预测模型的研究

物联网中,无线传感器网络由于环境、资源等因素的变化和限制,会导致部分数据异常或丢失,使数据传输的可靠性降低。因此常用的BP神经网络方法在根据最终获取数据进一步处理时的准确性不高。提出K近邻算法和BP神经网络相结合的二阶段预测模型,先使用K近邻算法对BP神经网络输入数据中异常或缺失数据进行估值和替换预处理,同时进行初步预测,然后将预处理后的数据输入BP神经网络,综合BP神经网络和KNN的预测结果给出最终结论。实际环境中实验表明,所提出的模型能够有效地提高物联网环境中预测的准确度和稳定性。     

基于多模板匹配的双模型自适应相关滤波跟踪算法

为有效提升目标跟踪的精确度和实时性,设计了基于多模板匹配的双模型自适应相关滤波跟踪算法。对多模板匹配模型与核相关滤波跟踪模型参数进行初始化处理：多模板匹配模型选取得分函数作为模板与候选样本间匹配准则,通过候选样本得分获取最佳目标,更新多模板后,通过形变多样相似性实现多模板匹配;核相关滤波跟踪模型利用所采集目标样本数据建立循环矩阵,通过训练核化岭回归分类器获取核相关滤波器,并获取响应置信图,再利用响应置信图获取下一帧图像目标位置。通过自适应融合策略获取两个模型所估计目标位置,再采用金字塔尺度估计策略估计目标尺度变化,通过不断更新各模型参数实现目标精准跟踪。实验结果表明,在目标受遮挡或旋转、光照变化等复杂环境下,该算法的中心跟踪误差均低于15 dpi,平均跟踪精确度均高于98%,且目标定位时间低于100 ms,说明该算法在跟踪精确度和实时性上具有明显的应用优势。     

Three-dimensionally ordered,ultrathin graphitic-carbon frameworks with cage-like mesoporosity for highly stable Li-S batteries

Mesoporous carbons have been widely utilized as the sulfur host for lithium-sulfur (Li-S) batteries.The ability to engineer the porosity,wall thickness,and graphitization degree of the carbon host is essential for addressing issues that hamper commercialization of Li-S batteries,such as fast capacity decay and poor high-rate performance.In this work,highly ordered,ultrathin mesoporous graphitic-carbon frameworks (MGFs) having unique cage-like mesoporosity,derived from self-assembled Fe3O4 nanoparticle superlattices,are demonstrated to be an excellent host for encapsulating sulfur.The resulting S@MGFs exhibit high specific capacity (1,446 mAh·g-1 at 0.15 C),good rate capability (430 mAh.g-1 at 6 C),and exceptional cycling stability (～0.049％ capacity decay per cycle at 1 C) when used as Li-S cathodes.The superior electrochemical performance of the S@MGFs is attributed to the many unique and advantageous structural features of MGFs.In addition to the interconnected,ultrathin graphitic-carbon framework that ensures rapid electron and lithium-ion transport,the microporous openings between adjacent mesopores efficiently suppress the diffusion of polysulfides,leading to improved capacity retention even at high current densities.     

低渣比冶炼锰硅合金的条件与操作要点

论述了低渣比冶炼锰硅合金的条件和操作要点，阐明了炉料中Al2O3与电炉工艺参数、焦炭粒度之间的相互关系及其对电耗等指标的影响。     

乳化炸药油水相流量控制

以乳化炸药生产线油、水相流量控制系统为研究对象,分析油、水相流量添加过程的滞后性,针对传统PID控制理论的不足,详细分析了自校正PID理论,采用自校正PID控制策略来实现流量的实时控制。现场运行情况表明,这种控制策略符合工业实际,采用的控制器稳定可靠。     

Construction of plate-like magnetic heterostructure for synergistic microwave absorption

The dramatically dropped permeability of magnetic materials at gigahertz frequencies, known as the Snoek's limit, has severely constrained the microwave absorbing performance of magnetic materials. To break the Snoek's limit at high frequencies, a plate-like magnetic heterostructure composed of Ni-Fe ferrite, nitride, and Permalloy is fabricated through nitridation of Ni-Fe layered double hydroxide. It has been found that single-phase magnetic flakes or the multi-phase heterostructure with extraordinarily linked magnetic nanoplates can be obtained by simply adjusting the temperature of nitridation. Due to the highly anisotropic morphology and synergistic effect at abundant heterogeneous interfaces, the magnetic heterostructure shows enhanced imaginary permeability that is even higher than that of single-phase Permalloy. Accordingly, the magnetic loss in C and X bands is improved, leading to significant enhancement of attenuation constant in this novel microwave absorber. Combined with the moderate permittivity, the impedance matching of the heterostructure is superior compared to every single component, as well as the mixture of these components. As a result, the minimum reflection loss of −59.30 dB at a thickness of 2.02 mm and effective absorption bandwidth (RL<−10 dB) of 2.44 GHz is realized. These findings provide a novel path to designing high-performance microwave absorbers based on magnetic materials.     

超声辅助酶解大米多肽的制备及其对酵母细胞增殖性影响

采用超声辅助酶解制备大米多肽,并研究其对酵母细胞增殖性的影响。在单因素试验基础上,对超声辅助酶解制备大米多肽进行工艺优化,确定最优超声辅助酶解工艺:超声功率密度51.8 W/L、超声温度50℃、超声时间15 min。在最优工艺条件下,大米多肽得率为70.57%。对酵母细胞培养增殖显示随着多肽浓度的增加而增强,当多肽浓度达到25 g/L后,酵母细胞增殖效果不再增强;另外超声辅助酶解的大米蛋白多肽作为氮源对酵母细胞培养增殖效果要好于常规酶解。     

聚脲基涂层对碳纤维布加固混凝土力学性能影响的研究

为了提高碳纤维布加固混凝土中碳纤维材料与混凝土之间相互作用的性能,研究提出在混凝土和碳纤维布之间增加一层柔性聚脲基涂层,通过模型试验及有限元仿真计算的手段,对比分析了有无聚脲基涂层对碳纤维布加固力学性能的影响。试验结果表明,含有聚脲基涂层时可以改善界面处的粘结性能,提高其剥离承载力和界面剥离破坏能等。基于双线性内聚力的界面粘结—滑移关系曲线,运用有限元分析软件ABAQUS分别对聚脲基涂层有/无两种工况进行非线性有限元仿真分析。模拟结果表明,当含有聚脲基涂层时,数值分析结果和试验结果具有较好的一致性。试验结果和数值解均证明了聚脲基涂层可以提高碳纤维布(CFRP)和混凝土基面之间的极限承载力和界面剥离破坏能,对水工结构碳纤维加固实际应用具有参考价值。