基于Isolation Forest的并行化异常探测设计

异常探测具有广泛的应用,受到了工业界和学术界的共同关注。在众多异常探测方法中,Isolation Forest算法具有执行效率高、探测准确度好的特点,获得了众多应用。但是,传统Isolation Forest算法难以处理大规模数据。为解决此问题,设计了一种基于云计算平台的算法。具体地,使用Hadoop分布式存储系统和MapReduce分布式计算框架设计并实现了基于Isolation Forest的并行化异常探测算法PIFH。通过将探测模型构建和数据异常评价的过程并行化,提升了PIFH算法探测异常的执行效率,扩展了其应用范围。利用真实世界数据集验证了所提算法的执行效率和可扩展性。     

BRT屏蔽门系统站点远程监控终端设计

设计了一种BRT屏蔽门系统的站点远程监控终端.以STM32F407ZGT6作为主控芯片构建终端的硬件系统,阐述了网络接口设计、本地存储设计、CAN通信电路设计、无线遥控设计.终端在软件上移植μC/OS-Ⅲ系统,保证终端的多任务实时进行;移植LWIP,实现基于HTTP的网络通信、远程配置等功能.实验结果表明,屏蔽门系统能正常工作,站点远程监控的实时性、安全性较高.     

Electronic structures of quasi-one-dimensional ferrimagnetic insulator Ca3Co2O6

The electronic structures of quasi-one-dimensional ferrimagnetic Ca₃Co₂O₆ are investigated using the generalized gradient approximation (GGA) as well as the GGA plus on-site Coulomb interaction (GGA+U) scheme. GGA+U calculations reveal that the interchain ferrimagnetic Ca₃Co₂O₆ is a Mott–Hubbard insulator rather than a metal given from GGA. In addition, we found an on-site U induced 3z²−r² orbital ordering on Co_pri sublattice which drives the intrachain ferromagnetic coupling along c-axis. Our findings suggest that strong electron-electron correlation plays an important role in Ca₃Co₂O₆.     

Robust anti-windup controller design of time-delay fuzzy systems with actuator saturations

This study presents a robust anti-windup fuzzy control approach for uncertain nonlinear time-delay systems with actuator saturations. The discussed system dynamics is presented by the Takagi-Sugeno (T-S) fuzzy model. To facilitate the design process, the nonlinearity of input saturation is characterized by a specific sector condition. Given a stabilizing dynamic output feedback fuzzy controller, an anti-windup control approach is then developed to maximize the size of estimate of the domain of attraction. Significantly, the convergence of all admissible initial states within this region could be ensured. Based on the Lyapunov-Krasovskii delay-independent and delay-dependent analyses, sufficient conditions for the robust stabilization are derived. These conditions are formulated as a convex optimization problem with constraints represented by a set of linear matrix inequalities, allowing the fuzzy controller to be synthesized more efficiently. Finally, numeric simulations are given to validate the proposed approach.     

Vortex pattern and wave motion produced by a bottom blunt body moving at a critical speed

An underwater object moving at a near-critical speed in a shallow-water domain had been observed to generate a sequence of upstream propagating solitary waves with an elongated depression of water surface and a train of dispersive waves followed in the downstream. This study presents the development of a two-dimensional stream function–vorticity based viscous fluid model with satisfied nonlinear free-surface conditions to study the generation of solitary waves and the induced vortex motion under the forcing of a moving object. A combined finite analytic and finite difference method is adopted to solve the flow field equations and free-surface boundary conditions in a transient curvilinear coordinate system. The model is shown to produce free-surface elevations in fairly good agreements with published results for a test case of a moving smooth bump. Other tests for the generation of recirculation zone behind a body of square shape in a confined fluid domain are also conducted to further verify the model performance. The results showing the generation of upstream advancing solitary waves and downstream vortex pattern by a blunt rectangular body moving at a critical speed along the bottom in a domain with free surface are presented. Comparisons of results from potential flow and viscous flow conditions are made to demonstrate the importance of viscosity to the wave generation. Different from the relatively regular vortex pattern occurred under the case of Re = 3500, the transition of the vortex motion for a larger Reynolds number (e.g. Re = 35,000) evolves without a regular pattern throughout the generation process of the advancing solitons. The effects of the size and bluntness of a moving object on the generated flow field and free-surface elevations are also analyzed and discussed.     

Prediction of residual stresses in high strength carbon steel pipe weld considering solid-state phase transformation effects

In this paper, prediction of axial and hoop residual stresses produced in high strength carbon steel pipe weld was made by employing a sequentially coupled 3-D thermal, metallurgical and mechanical FE model. Solid-state phase transformation during welding was incorporated into the FE model by allowing for volumetric changes and the associated changes in yield stress induced by austenitic and martensitic transformations. In the FE model, temperature-dependent thermo-physical and mechanical properties were considered, and phase transformation plasticity was also taken into account. The results showed the importance of incorporating solid-state phase transformation in the simulation of the pipe welding.     

RFID-initiated workflow control to facilitate patient safety and utilization efficiency in operation theater

Objective

To control the workflow for surgical patients, we in-cooperate radio-frequency identification (RFID) technology to develop a Patient Advancement Monitoring System (PAMS) in operation theater.

Methods

The web-based PAMS is designed to monitor the whole workflow for the handling of surgical patients. The system integrates multiple data entry ports Across the multi-functional surgical teams. Data are entered into the system through RFID, bar code, palm digital assistance (PDA), ultra-mobile personal computer (UMPC), or traditional keyboard at designated checkpoints. Active radio-frequency identification (RFID) tag can initiate data demonstration on the computer screens upon a patient's arrival at any particular checkpoint along the advancement pathway.

Results

The PAMS can manage the progress of operations, patient localization, identity verification, and peri-operative care. The workflow monitoring provides caregivers’ instant information sharing to enhance management efficiency.

Conclusion

RFID-initiate surgical workflow control is valuable to meet the safety, quality, efficiency requirements in operation theater.     

减少防撞雷达虚假目标的信号处理研究

从信号处理的角度分析了防撞雷达虚报警率、漏报警率偏高的原因,采用AR模型功率谱估计的Burg算法代替传统的FFT算法,并将粗神经网络应用于防撞雷达目标识别。仿真结果表明,此方法提高了雷达信号处理的准确度和目标识别率,能有效地降低漏报警、虚报警率。     

杜仲松脂醇二葡萄糖苷含量的近红外光谱检测研究

采用AntarisⅡ傅立叶变换红外光谱分析仪器(Thermo Nicolet)测定了9种杜仲的光谱数据,运用偏最小二乘法(PLS)和主成分分析回归(PCR)分别建立了杜仲中松脂醇二葡萄糖苷(PDG)含量与吸光度变量的近红外光谱定标模型,并对所建模型进行验证.结果表明,2种方法建立的模型精度都较高,其中模型的预测能力强弱指标SSE=2.8333,PRESS=7.2392,可见在近红外光谱下,PCR和PDG都适合对杜仲进行检测研究,这是本文的一个重要结果,为以后杜仲的指标检验研究提供了理论和实验依据:但是,PCR建立的(PDG)定标模型预测精度稍高于偏最小二乘法(PLS)建立的模型,所以文中只对PCR进行模型的建立,PLS方法对杜仲检测分析这个问题有待于以后的进一步讨论和研究.     

基于对数的NTC热敏电阻测温系统的设计

针对NTC热敏电阻阻值与温度(R-T)的非线性特性,为了提高测温精度,提出一种三阶对数公式法对R-T特性进行分段曲线拟合.该测温系统以三阶对数公式为基础进行了软硬件设计,实现了对船用柴油机的机油温度、冷却水温度的高精度测量.通过实验测试表明,在0～120℃温度范围内,采用该测温系统的测温误差小于±0.3℃.该测温系统已...