基于特征选择的相对k子凸包分类方法

k子凸包分类方法在实际问题中有广泛应用。但随着问题维数的增加,该方法计算得到的凸包距离非常接近甚至相等,这严重影响了分类性能。针对此问题,本文设计了一种基于特征选择的相对k子凸包分类方法。首先根据绝对凸包距离存在的不足引入相对k子凸包距离,然后在k邻域内利用判别正则化技术进行特征选择,并将特征选择融入相对k子凸包优化模型中,为每个测试样本在不同的类别中学习一个自适应的特征子集,从而得到一个用于分类的有效相对k子凸包距离。实验结果表明,该方法不仅能够进行特征选择,而且分类性能也有了明显提高。     

Fault-tolerant control for a class of non-linear systems with dead-zone

In this paper, a fault-tolerant control scheme is proposed for a class of single-input and single-output non-linear systems with the unknown time-varying system fault and the dead-zone. The non-linear state observer is designed for the non-linear system using differential mean value theorem, and the non-linear fault estimator that estimates the unknown time-varying system fault is developed. On the basis of the designed fault estimator, the observer-based fault-tolerant tracking control is then developed using the backstepping technique for non-linear systems with the dead-zone. The stability of the whole closed-loop system is rigorously proved via Lyapunov analysis and the satisfactory tracking control performance is guaranteed in the presence of the unknown time-varying system fault and the dead-zone. Numerical simulation results are presented to illustrate the effectiveness of the proposed backstepping fault-tolerant control scheme for non-linear systems.     

硅酸镓镧高温色散COM参数数据库建立

为了声表面波(SAW)器件设计的便捷和准确,该文利用耦合模(COM)模型在FEMSDA软件基础上添加了Mo、Pt、Ir 3种金属电极的材料参数,同时将硅酸镓镧(LGS)的材料参数随温度变化的关系式一起加入软件,以(0°,138.6°,26.7°)LGS压电基片为目标,建立了在700 K下不同金属、相对膜厚及占空比条件下的COM色散参数数据库。     

Wood‐Derived Materials for Advanced Electrochemical Energy Storage Devices

Over the past decade, wood‐derived materials have attracted enormous interest for both fundamental research and practical applications in various functional devices. In addition to being renewable, environmentally benign, naturally abundant, and biodegradable, wood‐derived materials have several unique advantages, including hierarchically porous structures, excellent mechanical flexibility and integrity, and tunable multifunctionality, making them ideally suited for efficient energy storage and conversion. In this article, the latest advances in the development of wood‐derived materials are discussed for electrochemical energy storage systems and devices (e.g., supercapacitors and rechargeable batteries), highlighting their micro/nanostructures, strategies for tailoring the structures and morphologies, as well as their impact on electrochemical performance (energy and power density and long‐term durability). Furthermore, the scientific and technical challenges, together with new directions of future research in this exciting field, are also outlined for electrochemical energy storage applications.     

联合生成与判别模型的目标检测与跟踪

提出了一种新的基于生成-判别模型的目标检测与跟踪方法。利用DAISY特征描述子所具有的对光照、形变、视角、尺度的不变性以及计算高效的特点,提取目标稳定的特征点并加以表达,形成生成模型;采用霍夫森林分类器作为判别模型,用以训练目标图像块。在后续视频序列中利用目标的检测结果和判别码本的相似性测量对模型进行更新,构建一个动态自适应的判别码本。实验证明这种将快速有效的DAISY描述子和识别率高、鲁棒性强的霍夫森林分类器相结合的算法,跟踪精度高、实时性较好,具有目标局部防遮挡能力和不同分辨率下的识别能力。     

Adaptive fuzzy tracking control for a class of uncertain MIMO nonlinear systems using disturbance observer

In this paper,the adaptive fuzzy tracking control is proposed for a class of multi-input and multioutput(MIMO)nonlinear systems in the presence of system uncertainties,unknown non-symmetric input saturation and external disturbances.Fuzzy logic systems(FLS)are used to approximate the system uncertainty of MIMO nonlinear systems.Then,the compound disturbance containing the approximation error and the timevarying external disturbance that cannot be directly measured are estimated via a disturbance observer.By appropriately choosing the gain matrix,the disturbance observer can approximate the compound disturbance well and the estimate error converges to a compact set.This control strategy is further extended to develop adaptive fuzzy tracking control for MIMO nonlinear systems by coping with practical issues in engineering applications,in particular unknown non-symmetric input saturation and control singularity.Within this setting,the disturbance observer technique is combined with the FLS approximation technique to compensate for the efects of unknown input saturation and control singularity.Lyapunov approach based analysis shows that semi-global uniform boundedness of the closed-loop signals is guaranteed under the proposed tracking control techniques.Numerical simulation results are presented to illustrate the efectiveness of the proposed tracking control schemes.     

变压吸附法富氧用于固定床煤气炉连续气化工艺技改方案的技术经济分析

概述了我国中氮肥行业固定床煤气炉空气间歇气化和富氧连续气化工艺技术现状，着重讨论了变压吸附法分离空气制富氧技术，分析论证了变压吸附法富氧用于Φ３０００ｍｍ、Φ２７４５ｍｍＵＧＩ型间歇式固定床煤气炉进行常压连续气化工艺的经济效果，并探讨了可行的技改方案。     

New investigation of 1‐substituted imidazole derivatives as thermal latent catalysts for epoxy‐phenolic resins

Novel 1‐substituted imidazole derivatives ( 4 – 10 ) were synthesized by imidazole and the corresponding substituted reagents (chloromethylpivalate, diphenylphosphinicchloride, di‐tert‐butyldicarbonate, 1,1′‐oxalylchloride, pyrazine, phneylisocyanat, and p‐toluensulfonylchloride). Polymerization of diglycidyl ether of bisphenol A (DGEBA) with 1‐substituted imidazole derivatives, two commercial available catalysts (imidazole and 1‐cyanoethyl‐2‐ethyl‐4‐methylimidazole) and N‐benzylpyrazinium hexafluoroantimonate were investigated as model reactions of epoxy resin systems with respect to the thermal latency and storage stability of the catalysts. The catalytic activity of 1‐substituted imidazole derivatives 4 – 10 depended on the steric and withdrawing electronic effect of the substitution groups. To characterize the cure activation energy and the viscosity‐storage time, the order of thermally latent activity is 1‐tosylimidazole ( 6 ) > 1,1′‐oxalyldiimidazole ( 8 ) > N‐benzylpyrazinium hexafluoroantimonate (BPH, 3 ) > 1‐tritylimidazole ( 9 ) > N‐phenyl‐imidazole‐1‐carboxamide ( 5 ) > 3‐(diphenylphosphinoyl)imidazole ( 7 ) > tert‐butyl‐1H‐imidazole‐1‐carboxylate ( 4 ) > 1‐cyanoethyl‐2‐ethyl‐4‐methylimidazole (2E4MZ, 2 ) > 1‐[(pivalyloxy)methyl]imidazol ( 10 ) > imidazole ( 1 ). In comparison with commercially available catalysts imidazole ( 1 ) and 1‐cyanoethyl‐2‐ethyl‐4‐methylimidazole ( 2 ) and a cationic latent catalyst N‐benzylpyrazinium hexafluoroantimonate (BPH, 3 ) as the standard compounds, in addition to 1‐[(pivalyloxy)methyl]imidazole ( 10 ), the 1‐substituted imidazole derivatives ( 4 – 9 ) revealed better thermal latency. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

SHEPWM实现方法及其在D-STATCOM中的应用

特定谐波消除SHEPWM具有通过开关时刻的优化选择消除选定频次谐波的特点.本文采用了一种较为精确SHEPWM开关角初始值的计算方法,将计算出的结果作为MATLAB函数fsolve的迭代初值求出a相控制脉冲的开关角,并根据三相对称的特点获得b、c相控制脉冲的开关角.在MATLAB/SIMULINK中建立SHEPWM仿真模型,并将其应用于直接电压控制的配电网静止同步补偿器(D-STATCOM)系统中.结果表明,该系统既能较好地维持D-STATCOM接入电网公共连接点电压的稳定又能有效消除逆变器输出电压的低次谐波含量.     

给水管网污染源定位模拟及影响因素分析

为了在供水管网突发污染发生时快速准确定位污染源,以小规模开环式供水管网模拟系统为实验平台,采用多点投加高浓度次氯酸钠溶液模拟污染物扩散的方法进行实验研究与理论分析.在实验中监测多组管网平台监测点污染物浓度时变数据,在保证可靠性、准确性的基础上将监测数据作为反追踪模拟信息源.通过改进的基于拉格朗日算法的“模拟-优化反追踪数学模型”定位污染源,分析管网拓扑结构、优化时段和水力工况等因素对模型精度和效率的影响.研究表明,在模型影响因素合理表达的条件下,模拟结果准确率达93.3%.