空分设备自动变负荷先进控制技术

以南钢20000m3/h空分设备为例,介绍国产大型空分设备自动变负荷控制系统的设计思路、优化控制及方案、技术特点、控制目标和控制策略等。阐述空分设备自动变负荷技术实现国产化的意义。     

自动变负荷及优化控制在空分设备中的应用

综述国内外大型空分设备的自动变负荷及优化控制技术的发展状况,分析自动变负荷及优化控制技术的难点,结合国内首套国产空分装置的自动变负荷及优化控制应用情况,对空分设备自动变负荷及优化控制的系统结构和操作流程等进行了较全面的阐述。     

大型空分设备技术现状及进展

介绍了大型空分设备的发展状况,结合杭氧空分设备设计制造的实际情况,对大型空分设备的技术现状及进展进行了叙述,指出空分设备的大型化、流程形式的多样化、变负荷技术的自动化和工程项目一体化是空分行业今后一个时期的主要研究方向。     

DCS在空分设备变负荷控制中的应用研究

简述了空分设备自动变负荷的工作原理和工作过程,以及CENTUM分散控制装置在金对两套 6500m3/h空分设备变负荷软件的实施情况,并对软件结构设计作了重点论述,提出变负荷控制技术是空分设备降低能耗,提高经济效益有利途径的观点。图7。     

南钢KDON-20000/30000型空分设备国产化自动变负荷技术应用实践

简介我国成功实施国产化自动变负荷技术的首套内压缩流程空分设备——南钢KDON-20000/30000型空分设备的流程,叙述了自动变负荷技术调试过程和运行情况,并提出了进一步优化的建议。     

空分设备变负荷调节主要参数的关系及计算

提高空分设备变负荷调节能力是解决钢铁企业氧气放散率高的主要措施之一,以KDON-18000/18000型空分设备为例,对变更空气量的变负荷调节进行了理论推演和试验研究,得出了变更空气量负荷变化时,空分设备各主要参数(空气量、氧气量、粗氩流量、膨胀空气量、膨胀空气旁通量、氩馏分量、空压机排气压力和下塔阻力等)的变化规律,建立了部分变负荷时的数学模型及试验关联式。根据关联式和数学模型,对空分设备在73%~106%负荷间的12个工况进行了各主要参数计算。对空分设备各部机进行综合分析,空分设备的综合变负荷能力比各单机要小。     

首钢新建35000m~3/h空分设备的流程及特点

简介了首钢氧气厂新建35000m3/h空分设备的工艺流程及技术参数,详细分析了常规变负荷和快速变负荷调节时空分设备的运行工况以及快速变负荷调节时的工艺特点。     

空分设备空冷岛夏季负荷不足的技术改造

由于空分设备空冷岛在高温季节运行时负荷不足,使空分设备夏季的气体产量不能满足生产需要。增加水冷式冷凝器,在夏季时并入空冷岛一起工作,来分担原空冷岛的一部分负荷,使整个空冷岛的运行负荷提高,空分设备全年都能满负荷运行。介绍改造方案的总体布置、工艺流程及其技术特点。     

空分设备自动控制技术的发展现状与展望

介绍目前空分设备的控制系统状态及控制技术水平,分析空分用户的用氧特点,阐述空分设备自动控制技术的发展趋势,提出"随动变负荷"概念在DCS系统内的实现展望,并且明确了空分设备对"寻优控制技术"的需求。     

空分设备自动变负荷控制技术综述

综述国内外大型空分设备的自动变负荷控制技术的发展状况,分析自动变负荷控制技术的难点,着重对空分设备先进控制系统结构和操作流程、模型预测控制基本原理及其在空分领域的研究成果等进行了较全面的阐述,最后对空分设备自动变负荷技术的发展进行了展望。     

Recognition of interacting rotational and prismatic machining features from 3-D mill-turn parts

Current feature recognition methods generally recognize and classify machining features into two classes: rotational features and prismatic features. Based on the different characteristics of geometric shapes and machining methods, rotational features and prismatic features are recognized using different methods. Typically, rotational features are recognized using two-dimensional (2-D) edge and profile patterns. Prismatic features are recognized using 3-D geometric characteristics, for example, patterns in solid models such as 3-D face adjacency relationships. However, the current existing feature recognition methods cannot be applied directly to a class of so-called mill-turn parts where interactions between rotational and prismatic features exist. This paper extends the feature recognition domain to include this class of parts with interacting rotational and prismatic features. A new approach, called the machining volume generation method, is developed. The feature volumes are generated by sweeping boundary faces along a direction determined by the type of machining operation. Different types of machining features can be recognized by generating different forms of machining volumes using various machining operations. The generated machining volumes are then classified using face adjacency relationships of the bounding faces. The algorithms are executed in four steps, classification of faces, determining machining zones, generation of rotational machining volumes and prismatic machining volumes, and classification of features. The algorithms are implemented using the 3-D boundary representation data modelled on the ACIS solid modeller. Example parts are used to demonstrate the developed feature recognition method.     

Color Image Steganalysis Based on Residuals of Channel Differences

This study proposes a color image steganalysis algorithm that extracts high-dimensional rich model features from the residuals of channel differences. First, the advantages of features extracted from channel differences are analyzed, and it shown that features extracted in this manner should be able to detect color stego images more effectively. A steganalysis feature extraction method based on channel differences is then proposed, and used to improve two types of typical color image steganalysis features. The improved features are combined with existing color image steganalysis features, and the ensemble classifiers are trained to detect color stego images. The experimental results indicate that, for WOW and S-UNIWARD steganography, the improved features clearly decreased the average test errors of the existing features, and the average test errors of the proposed algorithm is smaller than those of the existing color image steganalysis algorithms. Specifically, when the payload is smaller than 0.2 bpc, the average test error decreases achieve 4% and 3%.     

浅海中舰船辐射噪声非均匀调制特征分析

真实海洋环境下,信道复杂的畸变作用使目标分类识别特征的实际应用效果并不理想,因此寻找能够在信道中稳定传播的目标分类识别特征显得尤为必要。文章提取出平均窄带包络相关和最佳窄带包络相关两个非均匀调制特征来衡量舰船噪声在频带上的调制分布差异,并构建浅海相干多途信道的射线模型,通过仿真实验分析非均匀调制特征的传播变化。结果表明,舰船噪声的这种非均匀调制特征在相干多途信道的传播过程中具有良好的稳定性,是目标分类识别的一种稳定特征。     

一种快速的海面特征SAR成像仿真技术

水下物体运动引起扰动，会在海面产生尾迹。这种尾迹特征同运动物体的参数和下潜的深度以及海况有关。研究这种尾迹特征及其合成孔径雷达(SAR)成像，就有可能利用SAR来检测这个水下运动物体。本文给出了一种水下运动物体的伴流尾迹的快速模拟方法及其合成孔径雷达(SAR)成像仿真方法，并对模拟仿真的结果进行了讨论。     

凝固速率对Al-Ni合金组织特征的影响

采用气体雾化亚快速凝固工艺制备了Al-Ni合金粉末,并将粉末的组织形貌与金属模重力铸造的Al-Ni合金组织形貌进行了比较.实验结果表明,提高凝固速率可以使Al-Ni合金获得理想形貌的金属间化合物强化相.     

轴类零件二维工程图的特征识别方法

提出了轴类零件特征识别的方法.首先对特征进行了分类,接着建立了轴类零件的特征树模型,并且给出了实现该特征树模型的类结构;然后确定了主特征、辅助特征的识别原则和特征识别过程中的图形调整方法;最后描述了建立特征树的算法.在AutoCAD 2006环境下,以ObjectARX为开发工具,开发出了特征浏览器,实现了文中提出的原理和方法,以某典型轴类零件图为例进行了特征识别,识别效果良好.     

Identification of machining features based on available resources of cutting tools

In research on machining feature recognition, the problems of interacting features and availability of cutting tools are considered two major obstacles for developing industrial applications. In this research, a new machining feature recognition approach is developed to address these problems. In this work, a new concept called cutting mode is introduced to associate generic machining surfaces and cutting motions. In the feature recognition process, the machining surfaces of a part are first mapped to cutting modes, and these cutting modes are further mapped to available cutting tools. Among all the created candidate machining processes, heuristic rules are employed to identify the optimal solution that requires the minimum number of setups. When a number of machining surfaces are associated with a cutting tool in the same setup, these surfaces are grouped as a machining feature. Therefore the interacting features are recognised by the different cutting tools to produce these features. A database of available cutting tools is used to avoid the identification of features which cannot be machined in a machine shop. Three mechanical parts with interacting features are selected in the case studies to demonstrate the effectiveness of the developed approach.     

The response of the statistics of the cumulative features on grains in nanomaterials to different grain growth phenomena

Each nanomaterial grain has some number of features, such as faces or triple junctions, on it. The sum of all the features on all grains in nanomaterials, herein called cumulative feature, can be obtained. During grain growth both the number of features per grain and the cumulative features on all grain in nanomaterials evolve randomly with time. Different mechanisms are responsible for grain growth in nanomaterials. This includes Grain Boundary Migration, Grain Rotation-Coalescence, T1 and T2 events. Evolution models for number of features per grain are known already, and not model for evolution of cumulative features. The present paper uses the tools of stochastic theory given by Random Marked Point Field to propose models for the temporal and thermal evolutions of the statistics of the random cumulative features on grains in nanomaterials under different grain growth mechanisms. The resulting differential equations are solved simultaneously using data from nanocrystalline aluminium. It is observed that the mean number of features per grain increases and density of grains in nanomaterials decreases during grain growth. It is revealed that grain growth results in decrease in moments of the cumulative features. It is shown that an increase in annealing temperature results in relatively higher increase in mean number of features per grain, further decrease in grain density, relative increase in mean cumulative features on grain and variable dispersions of cumulative features. It is also observed that the evolution of the statistics of the cumulative features depends on the nature of Galzier-diffusion term, the form of the critical number of faces per grain and the type of grain growth mechanisms. For some choices of the Glazier diffusion term, the dispersion of the cumulative feature evolves in a manner similar to that of the nanomaterials mechanical properties given by the Hall–Petch to Reversed-Hall–Petch Relationship. The variables results are explained to be consequences of different grain growth mechanisms, temperature and the diffusion termed. Thus, it can be concluded that processing route, processing conditions and the nature of evolution of the constituents of nanomaterials are simultaneously vital when designing or characterising nanomaterials.     

基于单幅户外彩色图像实现天气晴阴分类

提出了一种新颖的利用随机森林对单幅户外彩色图像进行晴阴分类的方法。首先定义了天空频率直方图特征和阴影能量特征,给出了其计算方法,并将透射率特征引入天气分类中,将这3种特征与已有特征共同组合构成候选天气特征集;其次定义了Fisher-Random Forest特征重要性计算方法对天气特征进行选择;最后将选择后的天气特征以向量形式输入到随机森林分类器实现对户外图像的晴阴分类。实验结果表明:与其他方法相比,该方法具有较高的准确性及较好的通用性。