计算机在高炉鼓风机上的应用

本文介绍了捷克和斯洛伐克ＣＫＤ公司的ＭＡＲＫ工业控制计算机构成及其在高炉鼓风机控制系统中的应用，较详细地说明了高炉鼓风机的工艺控制思想。     

以ARM为核心的嵌入式体感遥控器设计

介绍一种以ARM为核心的嵌入式服务机器人体感遥控器的设计。硬件上,本遥控器采用具有ARM Cortex—M3内核的STM32F103C8T6作为核心处理器,选用ST公司的iNEMO惯性导航模块进行手部姿态的识别,同时还具有LCD显示模块、无线收发模块和电源模块;软件上,采用嵌入式操作系统μC／OS—Ⅱ实现多任务的调度和外围设备的管理。经实验验证,本遥控器具有高稳定性、高实时性、高可靠性、低误码率等优点。     

Querying Big Data: Bridging Theory and Practice

Big data introduces challenges to query answering, from theory to practice. A number of questions arise. What queries are ＂tractable＂ on big data？ How can we make big data ＂small＂ so that it is feasible to find exact query answers？When exact answers are beyond reach in practice, what approximation theory can help us strike a balance between the quality of approximate query answers and the costs of computing such answers？ To get sensible query answers in big data,what else do we necessarily do in addition to coping with the size of the data？ This position paper aims to provide an overview of recent advances in the study of querying big data. We propose approaches to tackling these challenging issues,and identify open problems for future research.     

神农大酒店地源热泵空调系统技术方案分析

为了提高地源热泵空调系统的能效比并降低地源热泵空调系统地埋换热器的换热器面积,减小系统投资,对神农大酒店地源热泵空调系统采用不同技术方案,从系统热负荷、全年不平衡热负荷、冷却水流量、系统能效比等几方面进行理论分析,经综合比较,采用冷热一体机与热水机串联+冷却塔辅助散热的复合式系统方案优于其他方案。但此方案受制于目前市场上冷热一体机的冷凝器和热水机蒸发器的循环水流通截面积不相等,引起流动阻力增加,影响使用效果。因此开发出冷热一体机的冷凝器和热水机蒸发器的循环水流通截面积相等的产品,是科研工作者和生产厂家要解决的首要问题。     

考虑储能自适应调节的双馈感应发电机一次调频控制策略

双馈感应发电机在常规超速减载控制下虽然可保留部分有功备用参与系统调频,但存在风电机组发电效益降低、转速调节范围减小及桨距角控制起动频繁等问题.为此,该文结合双馈风电机组网侧变流器的控制特性,提出计及超级电容储能荷电状态(SOC)控制的双馈感应发电机的惯量与一次调频自适应控制策略.在维持储能SOC的基础上结合惯性与下垂控制优势,提出可随频率偏差值和频率偏差变化率变化而自动调整两种调频控制参与调频的比例系数模型,实现两种调频模式的平滑切换,提升一次频率调节效果,提高单台风电机组的致稳性和抗扰性.最后通过仿真实验表明双馈感应发电机的惯量支撑和一次频率调节能力及发电效益较常规一次频率控制具有明显提高,为双馈感应发电机的改造升级提供了新思路.     

反向凝固母带拉速对结晶器流场影响的数值模拟

在连续统一模型的基础上建立了描述反向凝固结晶器中的流动与传热的数学模型。利用有限差分方法，计算出了反向凝固结晶器中母带厚度的变化规律，随着母带在钢液中停留时间的增加，母带厚度初期迅速增长，中期平衡相持，后期快速回熔；并进一步研究了反向凝固母带拉速对结晶器中流场的影响情况，拉速较小时，紧贴母带的钢液随母带-同运动，对整个流场的影响不大，当拉速较大或拉速变化较大时，部分甚至整个流场都发生了变化。计算结果表明采用数值模拟求解结果与试验数据是吻合的，证明假设合理，模型正确。     

弱电网下基于谐波状态空间模型的光储-虚拟同步发电机稳定性分析与优化控制研究

虚拟同步发电机(virtual synchronous generator, VSG)技术因提供阻尼和惯量而被广泛用于新能源并网逆变器。光储并入弱电网易发生频率耦合等问题,因而VSG并网稳定性分析变得更加复杂。针对光储并入弱电网系统,考虑频率耦合,在dq域中建立基于谐波状态空间(harmonic state space, HSS)理论的多时间尺度虚拟同步发电机模型。采用归一化参数灵敏度分析法,揭示功率环、电压环和低通滤波中虚拟惯量J、虚拟阻尼Dp、下垂系数Ku、比例系数kpu和截止频率ωc等关键控制参数根轨迹的特性和电网强度对系统稳定性的影响。并通过调整优化控制参数,提高系统稳定性。最后在Matlab/Simulink仿真平台验证谐波状态空间模型精确度和关键参数根轨迹特性。     

Study of tool trajectory in blisk channel ECM with spiral feeding

Electrochemical machining (ECM) plays an important role in blisk manufacturing. There are two steps in blisk ECM: machining of channels and precise shaping of blade profiles. In channel machining, channels are machined in the workpiece with allowance left to the following process. Therefore, the main aim of channel machining with ECM is to improve the allowance distribution. With this aim, a new ECM method for blisk channels, spiral feeding ECM, is developed in which the cathode feeds from blade tip to hub along with rotation motion around its axis. Through this combined motion, twisted channels are produced in the workpiece. The relationship between feed position and rotation angle is presented in the form of a mathematical model. Experiments with a feed rate of 1 mm/min confirm that spiral feeding ECM is feasible and efficient. Compared with radial ECM, the allowance differences in blank back and blank basin decrease by 32.7% and 33.6%, respectively. The surface roughnesses Ra in blank back, blank basin, and hub are 0.358, 0.308, and 0.102 µm, respectively. Thus, the allowance distribution is improved to be more uniform considerably and the surface quality is relatively high.     

Facial expression recognition using radial encoding of local Gabor features and classifier synthesis

Primarily motivated by some characteristics of the human visual cortex (HVC), we propose a new facial expression recognition scheme, involving a statistical synthesis of hierarchical classifiers. In this scheme, the input images of the database are first subjected to local, multi-scale Gabor-filter operations, and then the resulting Gabor decompositions are encoded using radial grids, imitating the topographical map-structure of the HVC. The codes are fed to local classifiers to produce global features, representing facial expressions. Experimental results show that such a hybrid combination of the HVC structure with a hierarchical classifier significantly improves expression recognition accuracy when applied to wide-ranging databases in comparison with the results in the literature. Furthermore, the proposed system is not only robust to corrupted data and missing information, but can also be generalized to cross-database expression recognition.