基于改进随机森林的新能源机组运行自动控制

由于在控制新能源机组运行过程中容易将数据边缘化，降低运行数据分类精度，导致控制结果与实际标准值不相符，提出基于改进随机森林的新能源机组运行自动控制方法。设置新能源机组运行过程可调节参数，采用改进随机森林构建自动控制模型，通过高精度决策树排序自动控制机组运行，实现新能源机组运行自动控制的目标。实验以新能源除湿机组为测试对象，分别在送风流量和溶液温度2个变量下，对机组的送风温度和含湿量进行控制。实验结果表明，所提方法控制后的机组运行参数与实际标准值基本一致，送风温度和含湿量误差均控制在较低水平，具有较高的实际应用价值。     

水轮机调相压水过程分析及其水位测量

某电站机组有调相运行的要求，但是在实际生产运行过程中由于对压水后水位的实际位置无法测量而导致调相运行失败。对机组调相压水的过程进行了简单分析，通过实例介绍了如何有效地测量压水后水位保证机组安全运行。     

继电保护运行若干问题研究

在电力系统中，继电保护为电网的安全运行提供了有力保障。然而由于我国对继电保护的应用较晚，理论及技术支持仍不够成熟，因而使得其在实际运行时仍存在若干问题。本文就当前继电保护在实际运行时暴露出的问题加以讨论，并建议性地提出其改进及运维管理措施，以提高其对电网系统的安全保护性能。     

基于状态切分与时间卷积网络的风电齿轮箱系统温度异常故障预警

由于风电齿轮箱结构复杂、运行工况多变，采用监控与数据采集系统（SCADA）数据对齿轮箱早期故障预警的精度不足。本文提出考虑风电齿轮箱润滑冷却状态及运行工况的状态切分方法，基于齿轮箱润滑冷却系统运行原理，从原始运行数据中选取相关参数，采用统计分析和聚类方法将齿轮箱系统时间序列数据进行运行策略分类切分，构建齿轮箱运行状态判断模型；提出采用时间卷积神经网络训练不同运行策略下的齿轮箱温度预测模型，并实时判断运行状态，选取对应运行策略温度预测模型，估计齿轮箱温度，通过与实际值之间的残差实现齿轮箱故障预警。实际案例表明，本文所提出的方法可以提高模型精度，能够有效预警风电齿轮箱系统的早期故障。     

工业锅炉现场运行分析浅谈

分析了工业锅炉现场运行分析基本要素，以实际案例说明加强工业锅炉现场运行分析的重要性。     

F-C201氢压机Ⅱ级活塞、活塞环的改造

将氢压机活塞、活塞环进行改造。活塞环由金属环改为复合型填充PTFE新材料，增加巴氏合金导向环，实际运行表明，运行周期增加数倍。     

ZTY系列天然气压缩机组润滑系统的改造

针对ZTY系列天然气压缩机组润滑系统在实际运行中所暴露的缺陷进行分析，提出改造措施．并详细阐述改造措施的可行性和效益评估，目的在于提高机组的润滑效果、降低机组运行成本和故障率，确保机组更能适合于实际生产的需要。     

数控系统的直线和S形加减速研究

推导出了用于机器人及机床控制器前加减速的直线加减速和S形加减速的离散采样迭代公式。实际减速点和理论减速点不重合，在减速过程中会出现一段时间的低速运行，为了消除低速运行段，提出了按照实际的剩余长度重新计算加速度和加加速度的算法，对该算法进行了仿真和实验验证，结果表明，该算法可有效地消除减速过程中的低速运行段。     

运行转子径向振动的小波信号监测

针对运行转子径向振动的信号监测，介绍了小波分析的基本原理，提出了运行转子异常信号检测的原则。利用该原则，本文对实际转子运行的径向振动信号进行了小波信号监测分析，得出了较好的结论。     

深冷装置用轴流通风机的改造与运行

针对深冷装置用轴流通风机现场运行中存在的问题，结合对该风机改造的过程，指出了其解决的办法及实际运行效果。     

PHENOMENON OF CARVED DRIVING WHEELS

A newly found phenomenon of carved driving wheels of a rear-wheel-drive tractor used in an airport is discussed. The circum of every driving wheel is damaged at three regions,which distribute regularly and uniformly. Everyday,the tractor tows a trailer which are times heavier than the tractor,and moves on the same road in the airport. The phenomenon is explained by the torsional self-excited vibration system of the powertrain. The simplified torsional vibration system is discribed by a 2-order ordinary differential equation,which has a limit circle. Experiments and numerical simulations show the followings: Because of the heavy trailer,the slip ratio of the tractor’s driving wheels is very large. Therefore,there is severe torsional self-excited vibration in the tractor’s drivetrain,and the self-excited vibration results in severe and regular fluctuations of the rear wheel’s velocity. The severe fluctuations in velocity fastens the damage of the driving wheels. At the same time,the time interval in which an arbitrary point in the circum of the driving wheel contacts with the road twice is two times more than the period of the torsional self-excited vibration,and this times explained the existence of three damaged regions. At last,it points out that the phenomenon can be avoided when the torsional damping is large enough.     

Effects of prebuckling deformations on the elastic flexural-torsional buckling of laterally fixed arches

The effect of the prebuckling in-plane deformations on the elastic flexural-torsional buckling of laterally fixed circular arches is studied in this paper. The finite strains and the energy equation for the flexural-torsional buckling of arches have been derived based on an accurate orthogonal rotation matrix. A closed form solution for the elastic flexural-torsional buckling resistance of laterally fixed arches in uniform bending, including the effects of the prebuckling deformations, is obtained. It is found that the notion that the prebuckling deformations increase the flexural-torsional buckling moment of an arch or of a beam is not necessarily correct for a laterally fixed arch or beam in uniform bending, in deference to a laterally pinned arch. When a laterally fixed arch is subjected to positive uniform bending, the effects of the prebuckling deformations decrease the buckling moment, and the reduction of the buckling moment increases with an increase of the included angle and of the out-of-plane slenderness ratio of the arch. When a laterally fixed arch is subjected to negative uniform bending, the effects of the prebuckling deformations decrease the absolute value of its buckling moment when the included angle is very small, but increase the absolute value of the buckling moment when the included angle exceeds a certain value. The increase in the absolute value of the buckling moment increases with an increase of the included angle and of the out-of-plane slenderness ratio of the arch. When the ratio of the out-of-plane to the in-plane second moments of area of the cross-section is not small, both the reduction of the buckling moment of a laterally fixed arch in positive uniform bending and the increase of the buckling moment of a laterally fixed arch in negative uniform bending, are substantial.     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.     

VOLUME DEFECT FATIGUE FAILURE OF CERAMIC BALLS UNDER ROLLING CONDITION

A newly developed pure rolling fatigue test rig with three contact points is used to test the rolling contact fatigue properties of silicon nitride ceramic balls. Ball surfaces are examined after failure with optical microscopy and scanning electron microscopy. The failure cause,fatigue phenomenon and mechanics are analyzed. The research shows that subsurface cracks play a dominant role in the formation of spalling failure. These cracks originated from volume defects of the material and propagate,to form elliptical fatigue spalls under the action of principal tensile stresses. The principal tensile stress increases with increasing contact load,causing spall formation and reduction of rolling contact life. The greater the principal tensile stress is,the more severe the peeling of near surface is. Under the same condition,the closer volume defects are to the surface,the more likely failure occurs,the shorter the rolling contact life is.     

OUT-OF-PLANE COMPRESSIVE PROPERTIES OF HEXAGONAL PAPER HONEYCOMBS

The compressive behaviour of paper honeycombs is studied by means of an experimental analysis. Experiment results show how geometry aspects of hexagonal paper honeycombs,e.g. the height of paper honeycomb,the thickness and length of honeycomb cell-wall,the drawing ratio of hexagonal honeycomb,affect the compressive properties of the paper honeycombs. It is in good agreement with the theory model. The constraint factor K of the critical buckling stress is mainly determined by the length of honeycomb cell-wall. It can be described as K=1.54 for B type paper honeycombs and K=3.32 for D type paper honeycombs. The plateau stress is the power exponent function of the thickness to length ratio of honeycomb cell-wall,and the experiment results show that the constant is 13.2 and the power exponent is 1.77. The research results can be used to characterize and improve efficiently the compressive properties of paper honeycombs.     

CONCURRENT PRODUCT PORTFOLIO PLANNING AND MIXED PRODUCT ASSEMBLY LINE BALANCING

Reconfigurable products and manufacturing systems have enabled manufacturers to provide "cost effective" variety to the market. In spite of these new technologies, the expense of manufacturing makes it infeasible to supply all the possible variants to the market for some industries. Therefore, the determination of the right number of product variants to offer in the product portfolios becomes an important consideration. The product portfolio planning problem had been independently well studied from marketing and engineering perspectives. However, advantages can be gained from using a concurrent marketing and engineering approach. Concurrent product development strategies specifically for reconfigurable products and manufacturing systems can allow manufacturers to select best product portfolios from marketing, product design and manufacturing perspectives. A methodology for the concurrent design of a product portfolio and assembly system is presented. The objective of the concurrent product portfolio planning and assembly system design problem is to obtain the product variants that will make up the product portfolio such that oversupply of optional modules is minimized and the assembly line efficiency is maximized. Explicit design of the assembly system is obtained during the solution of the problem. It is assumed that the demand for optional modules and the assembly times for these modules are known a priori. A genetic algorithm is used in the solution of the problem. The basic premise of this methodology is that the selected product portfolio has a significant impact on the solution of the assembly line balancing problem. An example is used to validate this hypothesis. The example is then further developed to demonstrate how the methodology can be used to obtain the optimal product portfolio. This approach is intended for use by manufacturers during the early design stages of product family design.     

OPTIMIZING DESIGN OF MECHANICAL SELF-CENTERING DEVICE FOR SUSPENSION HEIGHT

Firstly, in view of the respective defects of existing self-centering devices for vehicle suspension height, the design scheme of the proposed mechanical self-centering device for suspension height is described. Taking the rear suspension of a certain light bus as a research example, the structures and parameters of the novel device are designed and ascertained. Then, the road excitation models, the performance evaluation indexes and the half-vehicle model are built, the simulation outputs of time and frequency domain are obtained with the road excitations of random and pulse by using MATLAB/Simulink software. So the main characteristics of the self-centering suspension are presented preliminarily. Finally, a multi-objective parameter design optimization model for the self-centering device is built by weighted sum approach, and optimal solution is obtained by adopting complex approach. The relevant choosing-type parameters for self-centering device components are deduced by using discrete variable optimal method, and the optimal results are verified and analyzed. So the performance potentials of the self-centering device are exerted fully in condition of ensuring overall suspension performances.     

集中管理式公用电话计费系统

简要介绍了集中管理式公用电话计费系统的组成及功能.系统由公用电话集中管理中心与集中管理式电话计费器组成.集中管理中心与集中管理式电话计费器之间可通过公众电话网以拨号方式建立双向通信链路,从而实现对集中管理式电话计费器的远程管理.文中对集中管理式公用电话计费器的硬件设计作了系统的描述.自己设计了电话计费器与电话线的独特接口电路.对计费器软件的重点,即摘、挂机及拨号脉冲识别程序的设计,提出了一套完整的理论依据.     

The effect of basic nitrogen compounds on the tribological performance of sulphurised olefin

The effect of the molecular structure of basic nitrogen compounds on the lubricating properties of sulphurised olefin has been investigated using a Timken tester. X-ray Photoelectron Spectroscopy (XPS) and Energy Dispersive X-ray Analysis (EDAX) were used to study the chemical states of sulphur and nitrogen on the rubbed surfaces and the reaction rates of sulphur and iron separately. It was found that the antiwear and friction reduction properties of sulphurised olefin are greatly influenced by the different molecular structures of the basic nitrogen compounds. A composite additive package containing basic nitrogen compounds with sulphurised olefin can produce either synergistic or antagonistic effects, due to the influence of the different molecular structures of the basic nitrogen compounds. XPS analysis revealed that a tribochemical protective film containing nitrogen and sulphur was formed on the rubbed surface. EDAX analysis indicated that the reaction rates between elemental sulphur and iron were influenced by the different molecular structures of the basic nitrogen compounds. It was found that the apparent reaction rates of elemental sulphur and iron are related to the tribological characteristics of the additive package.     

IMPROVED METHOD FOR HILBERT INSTANTANEOUS FREQUENCY ESTIMATION

In the mechanical fault detection and diagnosis field, it is more and more important to analyze the instantaneous frequency (IF) character of complex vibration signal. The improved IF estimation method is put forward aiming at the shortage of traditional Hilbert transform. It is based on Hilbert transform in wavelet domain. With the help of relationship between the real part and the imaginary part obtained from the complex coefficient of continuous wavelet transform or the analytical signal reconstructed in wavelet packet decomposition, the instantaneous phase function of the subcomponent is extracted. In order to improve the precise of IF estimated out, some means such as Linear regression, adaptive filtering, resampling are applied into the instantaneous phase obtained, then, the central differencing operator is used to get desired IF. Simulation results with synthetic and gearbox fault signals are included to illustrate the proposed method.