增量型AGC模型稳定性研究

采用误差分析方法导出增量型自动厚度控制(AGC)模型设定序列的差分方程.根据该差分方程的特征值表达式讨论了AGC模型设定序列的稳定区域和稳态误差与AGC模型参数之间的关系.     

一种新型的预测功能控制算法

预测功能控制(Predietive Functional Control,PFC)算法是模型预测控制(Model Predictive Control,MPC)算法中的一种.它适合用来控制快速过程,并能使它快速无延迟地到达目标或设定点.本文将PFC算法扩展应用到线性离散系统差分方程模型,文中将详细介绍这种新型的PFC算法,即线性差分方程预测功能控制LDE-PFC(Linear Difference E-quation,PFC)算法.LDE-PFC算法主要由四部分组成线性差分方程,输出预测,参考轨迹和控制作用计算.基于预测控制目标函数,LDE-PFC算法就是要让预测输出尽可能接近参考轨迹,同时能尽量快速平滑地到达设定点.为了证明LDE-PFC算法的有效性,在Matlab/Simulink平台上研究和仿真了LDE-PFC算法在离散系统中的应用.仿真结果表明,LDE-PFC算法能快速无延迟地跟踪不同类型的快速变化的设定点.     

加热炉内钢坯二维导热差分方程的一维简化

利用总括热吸收率法对加热炉内钢坯加热过程进行模拟。分别对板坯和方坯导热差分方程进行一维和二维简化,比较其结果。在方坯的情况下,采用田中功模型进行描述。分析了二维模型与田中功模型的差别,并调整田中功模型下的总括热吸收率值,使其与二维模型结果基本相同。     

线性差分方程的实用稳定性

分析了一阶线性差分方程和二阶线性差分方程的实用稳定性.根据不等式性质及单调性准则,利用向量函数方法得到简便的实用稳定性条件.这些条件仅与系统的系数有关,易于直接验证.     

磨 分级过程的数学模型及广义预测控制研究

根据磨矿分级过程工艺和系统辩识理论，建立了磨矿分级过程控制系统的多变量差分方程模型，在此基础上，设计了多变量广义预测控制器，并进行了仿真研究。     

板形理论的进步与应用

金属塑性加工中板形理论的进步分三个阶段轧辊变形理论;轧件变形理论;轧件轧辊统一变形理论.本文推导出了四维轧制差分方程,以厚度为控制量的二维板形差分方程,以轧辊实时凸度和弯辊力为控制量的二维板形差分方程.构造了二次型目标函数,可用贝尔曼动态规划方法求出板形板厚最优控制综合,轧辊实时凸度估计和最佳弯辊力设定.     

低温还原铁矿微粉过程的数值模拟

研究了H2在360～400 ℃之间还原铁矿微粉的过程,并提出了微空间尺度下瞬时气固反应动力学模型,以模拟氧化铁微粉在低温下的还原过程.这个模型包括了非均相化学反应动力学方程、颗粒内的传热方程和气体扩散方程,采用全隐式有限差分方法对控制方程进行数值求解.通过数值计算得到不同颗粒度矿粉在不同温度下还原率随时间的变化, 并根据反应热和气体浓度在反应过程中的行为得知化学反应和气体内扩散在反应速率控制过程中所起的作用.数值模拟结果与试验结果基本吻合.     

热轧带钢层流冷却过程的温度预测模型

 通过分析热轧带钢在层流冷却过程中的能量变化,利用焓法模型建立了热轧带钢通过层流冷却段的能量平衡方程。然后利用相变热力学和相变动力学模型得到热焓,最后采用有限差分求解能量平衡方程,得到层流冷却过程中带钢的温度场和热焓场,该模型的计算结果与实测值符合良好,能够准确地预测带钢冷却后的温度分布,同时明确了冷却过程实际上是带钢能量传递给周围环境的过程,并非温度不断下降的过程。     

钢锭液芯加热、液芯轧制热状态数学模型(之二)——钢锭加热过程数学模型

1.前言 钢锭加热数学模型包括金属不稳定态导热差分方程组,炉膛热平衡方程,炉壁不稳定态导热差分方程组,炉气-废气温度模型等。这些方程(组)在各自的边界条件下,联立求解可得出任意时刻的钢锭温度分布、炉壁温度分布、炉气温度、废气温度、热负荷等,并可进而得出体积平均温度、焓平均温度、凝固率等。但是,由于边界条件比较复杂(主要表现为炉内热交换过程复杂、加热过程不仅随时间而变,而且随炉况而变),     

安钢炉卷轧机控制冷却系统温度控制模型及稳定性分析

对安钢炉卷轧机的控制冷却系统进行了全面的介绍,结合中厚板卷生产情况,分析推导了其空冷和水冷数学模型,采用计算机进行差分方程的求解和模型的自学习,通过现场实际应用,控制精度满足了工业生产的要求,效果明显。     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

焦炭热性能指标意义浅析

通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。     

Results of treatment of cancer of the cardia

Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of antibiotics of chemotaxis of human leukocytes

The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed.     

Quality of life of relatives of mental patients

Usage of quality of life of psychiatric patients' relatives as the parameter of estimation of the quality of psychiatric care is considered. By means of standard questionnaire elaborated by the authors as well as by means of both individual and group conversations the quality of life was analyzed in 40 relatives which lived together with psychiatric patients. Different spheres of their life and difficulties (financial, social-psychologic, production) were examined in families with such patients. The defects of psychiatric care that had direct influence on the quality of life of the psychiatric patients' relatives are outlined.