板带轧机厚控系统非线性模型与故障模拟

为提高轧机液压压下厚度控制系统(H AGC)建模精度,考虑系统中伺服阀流量与阀口压力之间这一典型非线性关系,应用机理建模的方法建立了轧机液压压下系统的非线性动态仿真模型。研究结果表明：与线性模型相比该非线性模型更加贴近真实系统模型,可以更加准确、完善地反应各参数变化对系统输出的响应。利用该模型对各种典型故障进行模拟研究,可为系统的故障预测和诊断提供依据。实验研究证明了所建立的非线性模型的准确性和故障分析的合理性。     

板带轧机厚控系统非线性模型与故障模拟

正作为板带轧机核心技术的液压压下厚度控制系统,其运行状态的好坏直接关系到产品质量和轧机生产效率,对其建立精确的数学模型和进行故障模拟十分重要。以往针对轧机液压压下系统大多采用泰勒展开式线性化建模方法,这种方法只适合处理某一稳态工作点的情况不能准确描述系统的非线性特性。燕山大学的学者为提高轧机液压压下厚度控制系统(HAGC)建模精度,考虑系统中伺服阀流量与     

板带轧机厚控系统非线性模型与故障模拟

<正>作为板带轧机核心技术的液压压下厚度控制系统,其运行状态的好坏直接关系到产品质量和轧机生产效率,对其建立精确的数学模型和进行故障模拟十分重要。以往针对轧机液压压下系统大多采用泰勒展开式线性化建模方法,这种方法只适合处理某一稳态工作点的情况不能准确描述系统的非线性特性。燕山大学的学者为提高轧机液压压下厚度控制系统(HAGC)建模精度,考虑系统中伺服阀流量与阀口压力之     

HAGC系统动态响应对轧机振动的影响

HAGC系统通过"恒辊缝控制"保证轧件板型与厚度的均匀性,其动态特性对轧机压下动作有很大影响。对HAGC系统进行数学建模,并计算各元件相关参数,利用Matlab/SIMULINK对各扰动因素以及扫频信号下系统进行动态响应分析,得出其动态响应特性与轧机的振动特性具有一定的关联性。     

轧机APC系统中出现的混沌现象及特性分析研究

描述在连轧自动位置控制系统中振动现象对于厚度精度的影响,基于混沌现象来研究探讨连轧自动位置控制系统(APC)不规则运动,建立连轧自动位置控制系统(APC)停车后的模型.将Lyapunov特性指数作为混沌判据,对所建模型的混沌特性分析表明,该系统具有多种非线性振动形式.应用Poincare截面、分叉图和最大Lyapunov指数方法分析了参数波动对轧机厚度非线性振动的影响.     

唐钢1650 mm可逆式冷带轧机液压AGC动态模型的建立与仿真

建立了唐钢1650 mm可逆式冷带轧机液压AGC系统的动态模型,仿真了系统参数变化对轧制厚度及系统的动态品质的影响。仿真结果与理论分析及实际工况相一致。结果表明,所建立动态模型简单且便于分析轧制过程中各种因素对最后轧制精度的影响。     

中板轧机液压压下装置的设计计算

1.前言 液压压下厚度自动控制系统(AGC),是保证产品厚度精度的重要手段。它的特点是响应速度快,压下速度与加速度高,定位精度高等的优点。国内除武钢引进的轧机装备有此系统外,自行研制的大型轧机液压压下最先在太钢1700炉卷轧机上应用,并在此基础上,为上钢一厂及三厂的2350中板轧机研制了一套液压AGC系统。上钢一厂的系统已于1984年8月投入生产应用,本文介绍此装置液压系统的设计特点和计算。     

冷连轧机动态过程特性的仿真研究

在分析和研究冷连轧机组生产过程的基础上,以某厂1 520mm五机架冷连轧机为例,建立其动态特性数学模型.利用Matlab进行仿真研究,分析来料带钢性能参数波动以及板厚控制系统设定参数扰动对板带厚度精度的影响,仿真结果说明了这一动态模型的有效性.     

冷连轧动态变规格辊缝动态设定原理与应用

以变断面，变张力逆流求解非线性方程组动态变规格模型为基础，考虑了材料变形抗力偏差及轧机入口带钢厚度偏差来修正动态变规格过程辊缝的设定值，建立起冷连轧动态变规格辊缝动态设定系统。通过宝钢益昌1220冷连轧机组实际应用表明，该系统可以提高动态变规格过程轧制参数的稳定性，同时可以提高变规格过程中带钢的厚度精度，减少厚度超差长度。     

柳钢2800mm中板轧机液压自动厚度控制系统

介绍了柳钢2800mm中板轧机液压自动厚度控制（HAGC0系统工艺参数与系统的结构、特点和功能。系统还包括平面形状控制、动态规程自动和控制轧制技术，构成一个较完善的控制系统。     

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)     

Comparison of rates of infection of two methods of emergency ventricular drainage

The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies.     

浅析《野草》的版画特征

鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美".     

四辊破碎机车刀架的改造

针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。     

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.