期刊文献+
共找到6篇文章
< 1 >
每页显示 20 50 100
外高桥1 000 MW超超临界机组闭环控制系统设计 被引量:27
1
作者 刘潇 曹冬林 丁劲松 《中国电力》 CSCD 北大核心 2006年第3期70-73,共4页
外高桥1000MW超超临界机组是被控特性复杂多变且多变量相关的对象,协调控制系统采用负荷指令的静、动态前馈和汽轮机与锅炉间的解耦回路来保证控制品质;由于该机组锅炉为直流炉,燃水比既与负荷控制相关又与汽温控制密不可分,燃烧和给水... 外高桥1000MW超超临界机组是被控特性复杂多变且多变量相关的对象,协调控制系统采用负荷指令的静、动态前馈和汽轮机与锅炉间的解耦回路来保证控制品质;由于该机组锅炉为直流炉,燃水比既与负荷控制相关又与汽温控制密不可分,燃烧和给水控制系统采用以负荷指令为基础的比值控制加二者的解耦回路以基本保证燃水比;过热汽温控制采用以焓值调节器的指令修正给水流量指令来精确保证燃水比为主要手段,以喷水减温为辅助手段;Smith预估器被应用于过热、再热器喷水控制回路中,以解决汽温这种大迟延、大惯性对象的控制难题。 展开更多
关键词 超超临界机组 闭环控制 微过热蒸汽焓 燃水比 解耦控制 SMITH预估器 比值控制 变参数控制
下载PDF
基于煤层突出特征的工作面预测指标确定 被引量:6
2
作者 张玉柱 《煤矿安全》 CAS 北大核心 2021年第1期152-156,共5页
为了确定突出煤层工作面突出预测敏感指标及合理临界值,以四季春煤矿6号煤层为例,通过总结矿井及邻近区域6号煤层的煤与瓦斯突出特征,构建了6号煤层工作面突出预测指标敏感性考察标准,基于敏感性考察标准统一对比了各工作面突出预测指... 为了确定突出煤层工作面突出预测敏感指标及合理临界值,以四季春煤矿6号煤层为例,通过总结矿井及邻近区域6号煤层的煤与瓦斯突出特征,构建了6号煤层工作面突出预测指标敏感性考察标准,基于敏感性考察标准统一对比了各工作面突出预测指标比值敏感程度,确定了6号煤层敏感指标钻屑瓦斯解析指标和辅助预测指标钻屑量。采用实验室测试和历史数据拟合计算、现场考察修正、扩大应用确定三步递进式敏感指标临界值确定方法,确定了6号煤层工作面突出预测敏感指标钻屑瓦斯解析指标临界值为0.51 mL/(g·min^(1/2)),辅助预测指标钻屑量临界值为6 kg/m。 展开更多
关键词 工作面突出预测 敏感指标 临界值 钻屑瓦斯解析指标K1 预测指标比值
下载PDF
Ventricular repolarization markers for predicting malignant arrhythmias in clinical practice 被引量:16
3
作者 Yaniel Castro-Torres Raimundo Carmona-Puerta Richard E Katholi 《World Journal of Clinical Cases》 SCIE 2015年第8期705-720,共16页
Malignant cardiac arrhythmias which result in sudden cardiac death may be present in individuals apparently healthy or be associated with other medical conditions. The way to predict their appearance represents a chal... Malignant cardiac arrhythmias which result in sudden cardiac death may be present in individuals apparently healthy or be associated with other medical conditions. The way to predict their appearance represents a challenge for the medical community due to the tragic outcomes in most cases. In the last two decades some ventricular repolarization(VR) markers have been found to be useful to predict malignant cardiac arrhythmias in several clinical conditions. The corrected QT, QT dispersion, Tpeak-Tend, Tpeak-Tend dispersion and Tp-e/QT have been studied and implemented in clinical practice for this purpose. These markers are obtained from 12 lead surface electrocardiogram. In this review we discuss how these markers have demonstrated to be effective to predict malignant arrhythmias in medical conditions such as long and short QT syndromes, Brugada syndrome, early repolarization syndrome, acute myocardial ischemia, heart failure, hypertension, diabetes mellitus, obesity and highly trained athletes. Also the main pathophysiological mechanisms that explain the arrhythmogenic predisposition in these diseases and the basis for the VR markers are discussed. However, the same results have not been found in all conditions. Further studies are needed to reach a global consensus in order to incorporate these VR parameters in risk stratification of these patients. 展开更多
关键词 Electrocardiographic predictor VENTRICULAR REPOLARIZATION MARKERS VENTRICULAR FIBRILLATION Sudden cardiac death QT INTERVAL Corrected QT INTERVAL QT dispersion Tpeak-Tend INTERVAL Tpeak-Tend QT ratio
下载PDF
新安煤田某矿煤层突出预测敏感指标及临界值确定 被引量:4
4
作者 陈学习 张鹏欣 +1 位作者 侯沣峻 陈广健 《华北科技学院学报》 2019年第6期1-6,共6页
为了保证矿井的安全高效生产,需要合理确定煤层突出危险性的预测敏感指标及其对应的临界值。针对新安煤田某矿煤层突出预测指标,进行现场实地跟踪考察。通过“三率法”和基于临界度的方差分析法,确定在采掘过程中预测指标对突出危险性... 为了保证矿井的安全高效生产,需要合理确定煤层突出危险性的预测敏感指标及其对应的临界值。针对新安煤田某矿煤层突出预测指标,进行现场实地跟踪考察。通过“三率法”和基于临界度的方差分析法,确定在采掘过程中预测指标对突出危险性敏感性反馈的强弱程度,确定突出敏感指标的临界值。对该测试矿井考察的预报指标中,钻屑瓦斯解吸指标Δh 2和钻屑量S可作为主要敏感指标,临界值分别为200 Pa和6.0 kg/m。在煤层突出危险性的预测过程中,“三率法”发挥着重要作用。它能够真实有效的确定敏感指标及其对应的临界值。 展开更多
关键词 突出危险性预测 敏感指标 临界值 三率法
下载PDF
Analysis of Ankle-Brachial Index, Waist-Hip Ratio, Ejection-Fraction, Obesity, Smoking, Alcohol Habits, Diabetes and Hypertension as Independent Predictors of Complexity and Severity of Coronary Artery Disease
5
作者 Naveen Kumar Cheruku Adikesava Naidu Otikunta +1 位作者 Y. V. Subba Reddy Ravi Srinivas 《International Journal of Clinical Medicine》 2015年第11期838-844,共7页
Background: The present study was conducted to examine the association between various coronary risk factors and clinical parameters, with special emphasis on ankle-brachial index, in predicting the severity and compl... Background: The present study was conducted to examine the association between various coronary risk factors and clinical parameters, with special emphasis on ankle-brachial index, in predicting the severity and complexity of coronary artery disease. Methods: Patients diagnosed with coronary artery disease at our hospital between September-2012 and December-2014 were examined in this study. Selected patients were screened for cardiovascular risk factors including diabetes, hypertension, smoking, and alcohol habits as well as for clinical parameters including body-mass index, waist-hip ratio, ankle-brachial index, and ejection fraction. All patients underwent coronary angiography and were evaluated for severity of coronary artery disease (based on number of vessels involved) and complexity of coronary angiographic lesions (measured by computer-assisted Syntax score calculator). The collected data were analyzed to determine the role of cardiovascular risk factors and clinical parameters as predictors of complexity and severity of coronary artery disease. Results: A total of 211 patients (mean age: 54.64 ± 9.9 years;81% males) with coronary artery disease were analyzed. Findings revealed that diabetes mellitus (p < 0.001), hypertension (p < 0.001), smoking habits (p = 0.036), and low ankle-brachial index (p < 0.001) were independent predictors of complex coronary artery disease as measured by Syntax score. Significant associations were also evident between severity of coronary artery disease and diabetes mellitus (p < 0.001), hypertension (p < 0.001), and ankle-brachial index (p < 0.001). Conversely, other cardiovascular risk factors including body-mass index, alcohol habits, wait-hip ratio, and ejection fraction did not exhibit significant associations with severity and complexity of coronary artery. Conclusions: The early diagnosis of coronary artery can be predicated by evaluating diabetes, hypertension, and smoking habits in patients presenting with acute coronary syndrome. In addition, ankle-brachial index can 展开更多
关键词 Ankle-Brachial Index Cardiovascular Risk Factors Coronary Artery DISEASE Peripheral Arterial DISEASE predictor Syntax Score Waist-Hip ratio
下载PDF
信道预测和联合收发分集的RQAM误符号率性能分析 被引量:1
6
作者 李得兵 李光球 金徐凤 《计算机工程》 CAS CSCD 北大核心 2018年第1期121-127,共7页
为解决采用最小均方误差维纳信道预测的发射天线选择(TASP)/接收天线最大比合并(MRC)的无线通信系统设计问题,利用矩生成函数法和高斯Q函数的近似表达式,分别推导了时间选择性瑞利块衰落信道上矩形正交幅度调制(RQAM)和差分编码四相相... 为解决采用最小均方误差维纳信道预测的发射天线选择(TASP)/接收天线最大比合并(MRC)的无线通信系统设计问题,利用矩生成函数法和高斯Q函数的近似表达式,分别推导了时间选择性瑞利块衰落信道上矩形正交幅度调制(RQAM)和差分编码四相相移键控(DE-QPSK)的平均误符号率(ASER)的精确及近似表达式。数值计算和仿真结果证明了RQAM与DE-QPSK的ASER精确分析的正确性和近似分析的准确性,从而可以快速地确定收发天线数、信道预测器参数以及各种信道参数等对TASP/MRC系统ASER性能的影响。 展开更多
关键词 瑞利块衰落信道 最小均方误差 维纳信道预测器 发射天线选择 最大比合并 矩形正交幅度调制 平均误符号率
下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部