期刊文献+
共找到1,544篇文章
< 1 2 78 >
每页显示 20 50 100
A Case of Head Posture Control Training Combined with Breathing Training in the Treatment of Dysarthria Brainstem Infarction Patient
1
作者 Jingyi Li Kai Chen 《Journal of Clinical and Nursing Research》 2025年第2期40-45,共6页
This paper reports a case of cerebral stem infarction with quadriplegia and complete dependence on daily life.The course of the disease lasted more than 7 months.Frenchay's improved articulation Disorder Assessmen... This paper reports a case of cerebral stem infarction with quadriplegia and complete dependence on daily life.The course of the disease lasted more than 7 months.Frenchay's improved articulation Disorder Assessment Form has been assessed as severe articulation disorder.The patient has significantly improved his speech function and quality of life after systematic head control training,respiratory function training,articulation motor training,and articulation training.In the course of treatment,emphasis was placed on head postural control training and respiratory function training,and emphasis was placed on the strength and coordination training of articulatory organs,and the results were remarkable.After the patient was discharged from the hospital,the follow-up of basic daily life communication was not limited. 展开更多
关键词 Brainstem infarction Articulation disorder Breathing training head posture control training
暂未订购
Heading control method and experiments for an unmanned wave glider 被引量:3
2
作者 LIAO Yu-lei LI Yi-ming +2 位作者 WANG Lei-feng LI Ye JIANG Quan-quan 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第11期2504-2512,共9页
The control system designing of unmanned wave glider(UWG) is challenging since the control system is weak maneuvering, large time-lag and large disturbance, which is difficult to establish accurate mathematical model.... The control system designing of unmanned wave glider(UWG) is challenging since the control system is weak maneuvering, large time-lag and large disturbance, which is difficult to establish accurate mathematical model. The control system for the "Ocean Rambler" UWG is studied in this work. A heading control method based on S-surface controller is designed. For the "rudder zero drift" problem in trials, an improved S-surface control method based on rudder angle compensation is proposed, which can compensate the adverse effects from environmental forces and installation error. The tank test and sea trial results prove that the proposed control method has favorable control performance, and the feasibility and reliability of the designed control system are also verified. 展开更多
关键词 unmanned wave glider heading control S-surface control control system
在线阅读 下载PDF
Command Filtered Finite/Fixed-time Heading Tracking Control of Surface Vehicles 被引量:3
3
作者 Zhenyu Gao Ge Guo 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2021年第10期1667-1676,共10页
This paper investigates the heading tracking problem of surface vehicles with unknown model parameters.Based on finite/fixed-time control theories and in the context of command filtered control,two novel adaptive cont... This paper investigates the heading tracking problem of surface vehicles with unknown model parameters.Based on finite/fixed-time control theories and in the context of command filtered control,two novel adaptive control laws are developed by which the vehicle can track the desired heading within settling time with all signals of the closed-loop system are uniformly bounded.The effectiveness and performance of the schemes are demonstrated by simulations and comparison studies. 展开更多
关键词 Command filter finite-time control fixed-time control heading tracking control surface vehicles
在线阅读 下载PDF
Modeling and Control of Head of the Underwater Snake-like Robot Swimming 被引量:2
4
作者 Ke Yang Xu-Yang Wang +1 位作者 Tong Ge Chao Wu 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2014年第1期77-83,共7页
In order to solve oscillation of head of the underwater snake-like robot,the Central Pattern Generator( CPG)-based control scheme with head-controller was presented. The Kane dynamic model was constructed to be proces... In order to solve oscillation of head of the underwater snake-like robot,the Central Pattern Generator( CPG)-based control scheme with head-controller was presented. The Kane dynamic model was constructed to be processed with a commercial package MotionGenesis Kane 5. 3,to which the proposed control scheme was applied. The relation between CPG parameters and orientation offset of head was investigated. The target orientation of head-controller was calculated through a convenient method. The advantage of this control scheme is that the head of the underwater snake-like robot remains in the forward direction during swimming. To prove the feasibility of the proposed methodology,two basic motion patterns,swimming along the straight line and swimming along the curved path,had been implemented in our simulation platform. The results showed that the simulation platform can imitate the swimming of the underwater snake-like robot and the head of the underwater snake-like robot remains in a fixed orientation directed towards the target. The oscillation of head's orientation is inhibited effectively. 展开更多
关键词 underwater snake-like robot CPG-based control scheme head-controller MotionGenesis Kane 5.3
在线阅读 下载PDF
Introduction of Several Methods to Control Fusarium Head Blight (FHB)
5
作者 张荣 张敏 《中国农学通报》 CSCD 2008年第10期419-426,共8页
Fusarium head blight (FHB) is a worldwide destructive disease of wheat in the warm, semi-humid or humid regions, especially serious in China. The disease not only causes significant losses in yield and reduces grain q... Fusarium head blight (FHB) is a worldwide destructive disease of wheat in the warm, semi-humid or humid regions, especially serious in China. The disease not only causes significant losses in yield and reduces grain quanlity, but also induces toxin to contaminated seeds, which is harmful to the healthy of human and livestocks, So it is important to control it. There are several methods to control Fusarium head blight (FHB). Such as using Crop rotation, Soil cultivation and Fertiliser, biological control, Fungicides control, transgenes, resistance to control Fusarium head blight (FHB). All of these methods gain some effect, but also exist their deficiency. Sometimes crop rotation had no significant effect on DON contamination of wheat grain, subsequent reductions in DON contamination were inconsistent when using Soil cultivation and Fertiliser, Unfortunately, under field conditions, the biological control achieved has been shown to be variable and in some tests has failed to give any control, The use of fungicides, however, have not been consistently effective in controlling FHB and in reducing DON formation, transgene-silencing at different generations is a problem to use transgenes, Information on location of QTL for FHB resistance should improve dramatically in the near future on resistance to control Fusarium head blight (FHB). Therefore, it is pressing to improve control methods, especially to DON. 展开更多
关键词 赤霉病 预防措施 植物 小麦
在线阅读 下载PDF
A bull-heading water control technique of thermo-sensitive temporary plugging agent 被引量:4
6
作者 LIU Pingde WEI Falin +3 位作者 ZHANG Song ZHU Xiuyu WANG Longfei XIONG Chunming 《Petroleum Exploration and Development》 2018年第3期536-543,共8页
Aimed at the disadvantages of secondary damage to oil layers caused by the conventional bull-heading water control technique, a thermo-sensitive temporary plugging agent for water control was synthesized by water solu... Aimed at the disadvantages of secondary damage to oil layers caused by the conventional bull-heading water control technique, a thermo-sensitive temporary plugging agent for water control was synthesized by water solution polymerization and applied in the field with a new secondary temporary plugging technique. The optimization and performance evaluation of thermo-sensitive temporary plugging agent were carried out through laboratory experiments. The optimized formula is as follows:(6%-8%) acrylamide +(0.08%-0.12%) ammonium persulfate +(1.5%-2.0%) sepiolite +(0.5%-0.8%) polyethylene glycol diacrylate. The thermo-sensitive temporary plugging agent is suitable for formation temperatures of 70-90 ?C, it has high temporary plugging strength(5-40 k Pa), controllable degradation time(1-15 d), the apparent viscosity after degradation of less than 100 m Pa?S and the permeability recovery value of simulated cores of more than 95%. Based on the research results, secondary temporary plugging technique was used in a horizontal well in the Jidong Oilfield. After treatment, the well saw a drop of water cut to 27%, and now it has a water cut of 67%, its daily increased oil production was 4.8 t, and the cumulative oil increment was 750 t, demonstrating that the technique worked well in controlling water production and increasing oil production. 展开更多
关键词 bull-heading water control TECHNIQUE THERMO-SENSITIVE TEMPORARY plugging agent secondary TEMPORARY plugging TECHNIQUE thermal degradation property RESERVOIR protection
在线阅读 下载PDF
Numerical Simulation of Turret Moored Ship Performance in Variable Ice Drift Based on Heading Control
7
作者 周利 《舰船科学技术》 北大核心 2016年第S1期75-84,共10页
The frequent change in ice drift direction poses a significant challenge for turret moored ship in ice. Variability in ice drift is mainly caused by the winds and currents. To solve this problem, a new method with num... The frequent change in ice drift direction poses a significant challenge for turret moored ship in ice. Variability in ice drift is mainly caused by the winds and currents. To solve this problem, a new method with numerical simulation based on heading control is applied to reduce the risk of operation of The Arctic Tandem Offloading Terminal(ATOT),which includes an offloading icebreaker(OIB) moored to a submerged turret and a shuttle tanker moored at the stern of the OIB in this paper. An icebreaking tanker, MT Uikku, was modeled in a simulation program. Then the level ice load on the tanker was calculated with different ice thicknesses and drift speeds, after which a heading controller assisted with mooring system is used to simulate the horizontal motion of the tanker under the ice action. 展开更多
关键词 Numerical simulation Mooring system heading control Ice drift Ice loads
在线阅读 下载PDF
Cutting Characteristics of Force Controllable Milling Head
8
作者 Shirakashi Takahiro Shibuya Wataru 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2002年第S1期108-,共1页
In order to control cutting force and its direction i n milling operation, a new milling head was developed. The head has two milling cutters, which are connected by a pair of gears and rotate in opposite direction re... In order to control cutting force and its direction i n milling operation, a new milling head was developed. The head has two milling cutters, which are connected by a pair of gears and rotate in opposite direction respectively. Both up-cut and down-cut can be carried out simultaneously by t hese milling cutters. The each depth of cut, the ratio of up/down cutting depth , by these cutters can be also selected. The cutting force characteristics were experimentally discussed by changing the ratio. The cutting force and its locus can be also changed by the selection of the ratio of up/down cutting depth. For practical usage of the head the analytical prediction method of the cutting forc e characteristics under selected cutting condition was proposed based on the ene rgy approach method proposed, in which both of cutting force characteristics of a single milling cutter and the combined milling cutter under a selected up/dow n cutting depth ratio were analytically estimated based on the two dimensional c utting data. It was experimentally shown that in NC milling machine the cutting force locus was controlled in pre-determined direction under various tool paths . 展开更多
关键词 Cutting Characteristics of Force controllable Milling head
在线阅读 下载PDF
On-line current feed and computer aided control tactics for automatic balancing head
9
作者 李勇 陆永平 +1 位作者 须根发 夏松波 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2002年第2期205-207,共3页
In the designed automatic balancing head, a non contact induction transformer is used to deliver driving energy to solve the problem of current fed and controlling on line. Computer controlled automatic balancing expe... In the designed automatic balancing head, a non contact induction transformer is used to deliver driving energy to solve the problem of current fed and controlling on line. Computer controlled automatic balancing experiments with phase magnitude control tactics were performed on a flexible rotor system. Results of the experiments prove that the energy feeding method and the control tactics are effective in the automatic balancing head for vibration controlling. 展开更多
关键词 AUTOMATIC balancing balancing head ON-LINE control TACTICS
在线阅读 下载PDF
Damage Characteristics and Control Measures of Maize Head Smut
10
作者 Bai Yanfeng Jiang Long +5 位作者 Ren Haixiang Wang Yanping Wang Xiaomei Zong Chunmei Sun Xiaohuan Qi Yuxin 《Plant Diseases and Pests》 CAS 2014年第5期15-16,24,共3页
Maize head smut is a worldwide disease, widely occurred in most maize fields. The disease had occurred in large area in the late 1970s, and became a limiting factor restricting the improvement of maize yield and total... Maize head smut is a worldwide disease, widely occurred in most maize fields. The disease had occurred in large area in the late 1970s, and became a limiting factor restricting the improvement of maize yield and total yield in China. After efforts of several generations of agricultural scientific workers, the symp- toms, pathogen, infection pathway, infection conditions, infection regularity and resistance genetic law of maize head smut have been studied. This paper introduces the incidence symptoms, pathogen sources, infection pathway, infection conditions, and physiological races of maize head smut, and put forwards the corresponding prevention measures, such as crop rotation, selection of resistant varieties, seed dressing, soil treatment with fungicides, promoting seedling emergence and strengthening field management. 展开更多
关键词 Maize head smut Damage characteristics control measures
在线阅读 下载PDF
Effect of Thermomechanical Controlled Processing on Mechanical Properties of 490 MPa Grade Low Carbon Cold Heading Steel 被引量:1
11
作者 LI Zhuang 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2009年第3期43-48,共6页
Thermomechanical controlled processing (TMCP) of low carbon cold heading steel in different austenite conditions were conducted by a laboratory hot rolling mill. Effect of various processing parameters on the mechan... Thermomechanical controlled processing (TMCP) of low carbon cold heading steel in different austenite conditions were conducted by a laboratory hot rolling mill. Effect of various processing parameters on the mechanical properties of the steel was investigated. The results showed that the mechanical properties of the low carbon cold heading steel could be significantly improved by TMCP without heat treatment. The improvement of mechanical properties can be attributed mainly to the ferrite grain refinement due to low temperature rolling. In the experiments the better ultimate tensile strength and ductility are obtained by lowering finishing cooling temperature within the temperature range from 650 ℃ to 550 ℃ since the interlamellar space in pearlite colonies become smaller. Good mechanical properties can be obtained in a proper austenite condition and thermomechanical processing parameter. The ferrite morphology has a more pronounced effect on the mechanical behavior than refinement of the microstructure. It is possible to realize the replacement of medium-carbon by low-carbon for 490 MPa grade cold heading steel with TMCP. 展开更多
关键词 thermomechanical controlled processing TMCP low carbon cold heading steel low temperature rolling finishing cooling temperature
原文传递
Occurrence of Rice Dry Straight Head Disease and Its Control
12
作者 黄自安 刘小林 +2 位作者 倪春耕 胡宏云 王振荣 《Plant Diseases and Pests》 CAS 2010年第2期1-4,9,共5页
[Objective] Cause of disease and control measures of rice dry straight head disease in Chuzhou area was discussed. [Method] Field investigation and comprehensive analysis of the literature were conducted to study the ... [Objective] Cause of disease and control measures of rice dry straight head disease in Chuzhou area was discussed. [Method] Field investigation and comprehensive analysis of the literature were conducted to study the reason of dry straight head disease in Chuzhou area, some common control measures were summarized. [Result] The characteristic of main symptoms included incidence of single plant, incidence of cluster, inclusive incidence between clusters. Sporadic normal rice grains existed in diseased spikes under the incidence of grains. The main pathogenic factors of dry straight head disease were concentration of arsenic or lack of elements, belonging to physiological disease, while the effect of other pathogenic factors could not be excluded. Heavy application of organic fertilizer and crop rotation should be conducted, white soil field should be paid more attention about the changes of disease condition with more wet and dry roasting over fields. Application time of micro fertilizer should be chosen properly, while tillering final stage and pollen formation stage must be adjusted to avoid high temperature, irrigation management should also be improved. [Conclusion] The study could provide reference for preventing rice dry straight head disease. 展开更多
关键词 Rice dry straight head disease Research SYMPTOM Cause of disease Arsenic concentration Prevention and control measure
在线阅读 下载PDF
髓芯减压联合不同方法治疗早中期股骨头坏死的网状Meta分析 被引量:1
13
作者 郭玉祺 李嘉程 +2 位作者 卢博文 张加豪 李刚 《中国组织工程研究》 北大核心 2026年第15期3993-4009,共17页
目的:探讨髓芯减压联合不同治疗策略对早中期股骨头坏死患者的疗效及安全性评价。方法:系统检索PubMed、Web of Science、Cochrane Library、EMbase、中国知网、维普、万方和中国生物医学文献数据库,纳入截至2025-01-19发表的关于髓芯... 目的:探讨髓芯减压联合不同治疗策略对早中期股骨头坏死患者的疗效及安全性评价。方法:系统检索PubMed、Web of Science、Cochrane Library、EMbase、中国知网、维普、万方和中国生物医学文献数据库,纳入截至2025-01-19发表的关于髓芯减压联合治疗早中期股骨头坏死的随机对照试验。采用Cochrane偏倚风险评估工具对文献质量进行评价,运用GRADE系统评价证据等级,基于贝叶斯框架构建网状Meta分析模型。采用标准化均数差进行效应估计,结果以累积排序概率曲线下面积进行干预优效性排序。敏感性分析采用逐项剔除法评估模型稳健性,并通过基线协变量评估传递性假设。结果:最终纳入73项随机对照试验,共计5148例患者、5777个髋关节,涵盖15种联合治疗方法。结果显示:①在提高综合临床疗效方面,髓芯减压联合自体骨髓单核细胞浓缩注射、骨髓间充质干细胞移植、支撑性植骨及补肾活血类中药复方汤剂等均优于单纯髓芯减压,其中髓芯减压联合自体骨髓单核细胞浓缩注射显示出最优的干预效果(累积排序概率曲线下面积=96.23%);②在髋关节功能改善方面,髓芯减压联合中医药序贯治疗疗效最优(累积排序概率曲线下面积=93.85%);③在疼痛缓解方面,髓芯减压联合中成药(补肾活血+活血化瘀)与活血化瘀类中药复方汤剂效果突出;④在影像学改善方面,髓芯减压联合自体源性干细胞局部植入效果最佳(累积排序概率曲线下面积=82.56%);⑤在临床安全性方面,髓芯减压联合活血化瘀类中药复方汤剂在降低不良事件发生率方面具有相对优势(P<0.05)。为评估结果稳健性,采用逐项剔除法进行敏感性分析,显示模型稳定,主要干预结果对单项研究不敏感,传递性假设成立。结论:髓芯减压联合干细胞移植、中医药序贯治疗等多种治疗方案在改善早中期股骨头坏死临床疗效方面优于单纯髓芯减压,表现为关节功能保护、结构重建与疼痛控制等多重优势。考虑部分干预文献数量有限及研究质量差异,仍需高质量、多中心、大样本随机对照试验进一步验证。 展开更多
关键词 髓芯减压术 股骨头坏死 联合治疗 网状Meta分析 随机对照试验
暂未订购
山区河流新型取水口滤网防淤堵效果模拟研究
14
作者 曹湖沁 童思陈 +2 位作者 王棚 王祥 张倩倩 《水电能源科学》 北大核心 2026年第1期83-88,共6页
目前,预防山区河流取水口淤堵的方法属于被动措施,即让机组停机后人工拆洗过滤元件,此法低效耗时安全性差。针对传统篮式过滤器易堵塞、维修成本高等问题,提出了一种新型旋转式过滤器。采用FLUENT建立三维水流数学模型模拟清、浑水工况... 目前,预防山区河流取水口淤堵的方法属于被动措施,即让机组停机后人工拆洗过滤元件,此法低效耗时安全性差。针对传统篮式过滤器易堵塞、维修成本高等问题,提出了一种新型旋转式过滤器。采用FLUENT建立三维水流数学模型模拟清、浑水工况下滤网内部流场与压强场变化,分析了传统篮式与旋转式过滤器水头损失。研究表明,旋转式过滤器相较于传统篮式过滤器,能够有效减缓淤积物落淤,提高过滤器过水能力,有效延长滤网工作时间。研究结果可为山区河流取水口滤网改进与优化提供设计参考和理论依据。 展开更多
关键词 取水口防淤 旋转式过滤器 数值模拟 运行特性 水头损失
原文传递
蝶阀专用动力头的创新设计
15
作者 吴冰 葛于国 +2 位作者 孙灿兴 楼申琦 张春兰 《机电设备》 2026年第1期10-13,共4页
为深化蝶阀作动器的技术研发与产业化进程,赋能行业创新升级,系统剖析蝶阀动力头的核心设计原理和结构特征,阐明其在操作效能、密封性能和系统稳定性提升中的关键作用。通过多维度的设计解构和工程验证,揭示动力头在工业应用中的技术演... 为深化蝶阀作动器的技术研发与产业化进程,赋能行业创新升级,系统剖析蝶阀动力头的核心设计原理和结构特征,阐明其在操作效能、密封性能和系统稳定性提升中的关键作用。通过多维度的设计解构和工程验证,揭示动力头在工业应用中的技术演进路径与创新发展方向。研究成果不仅可为阀门作动器的优化设计提供理论支撑和实践范式,也可为行业同仁开辟新的技术思路。 展开更多
关键词 蝶阀 动力头 技术设计 应用 工业控制
在线阅读 下载PDF
髓芯减压可控回抽打压植骨治疗早期股骨头坏死
16
作者 贺强 郭华 +1 位作者 黄小强 孙彩虹 《中国矫形外科杂志》 北大核心 2026年第1期19-25,共7页
[目的]探讨改良髓芯减压可控回抽打压植骨治疗早期股骨头坏死的临床疗效。[方法]2021年2月—2022年2月在本院接受髓芯减压打压植骨手术的早期股骨头坏死患者40例纳入本研究,随机分为两组,20例采用可控回抽打压植骨器进行减压植骨(改良... [目的]探讨改良髓芯减压可控回抽打压植骨治疗早期股骨头坏死的临床疗效。[方法]2021年2月—2022年2月在本院接受髓芯减压打压植骨手术的早期股骨头坏死患者40例纳入本研究,随机分为两组,20例采用可控回抽打压植骨器进行减压植骨(改良组),另外20例采用常规技术减压植骨(常规组)。比较两组围手术期、随访及影像资料。[结果]改良组切口总长度显著长于常规组[cm,(3.7±0.4)vs(3.4±0.5),P=0.044],但是前者的植骨量显著少于后者[g,(1.8±0.3)vs(2.1±0.4),P=0.002]。两组均获随访24个月以上。两组完全负重活动时间的差异无统计学意义(P>0.05)。术后随时间推移,两组VAS评分、Harris评分、髋伸-屈ROM、髋内-外旋ROM均显著改善(P<0.05),相应时间点,两组间上述指标的差异均无统计学意义(P>0.05)。两组术后24个月均有3髋行THA翻修。影像方面,随术前及术后12、24个月的时间推移,两组ARCO分期、Tönnis分期均无显著变化(P>0.05)。术后2年,改良组股骨头塌陷发生率(25%vs 30%,P=0.015)显著低于常规组,而前者的股骨头生存率显著高于后者(75%vs 70%,P=0.015)。[结论]本研究中改良的髓芯减压可控回抽打压植骨器,克服了常规技术不能可控回抽的缺点,节约了植骨材料,并且将术后2年股骨头生存率提高了5%。 展开更多
关键词 股骨头坏死 打压植骨 髓芯减压术 可控回抽
原文传递
Head Orientation Stability of Underwater Snake-Like Robot Swimming
17
作者 Ke Yang Xuyang Wang +1 位作者 Tong Ge Chao Wu 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2015年第2期18-25,共8页
In prior research,the orientation of head of the snake-like robot is changed according to the sinusoidal wave. To solve this problem,we propose Central Pattern Generator( CPG)-based control scheme with head-controller... In prior research,the orientation of head of the snake-like robot is changed according to the sinusoidal wave. To solve this problem,we propose Central Pattern Generator( CPG)-based control scheme with head-controller to stabilize the head of the underwater snake-like robot. The advantage of the CPG-based control scheme with head-controller is that the head of the underwater snake-like robot is direct to the target orientation during swimming. The relation between CPG parameters and orientation stability of head is discussed.The adaptation of the proposed method to environment changes is tested. The influences of CPG parameters and hydrodynamic forces on the orientation offset of head are investigated. The target orientation( the input of headcontroller) with an experimental optimization is calculated through a convenient method. To prove the feasibility of the proposed methodology,the different swimming modes have been implemented in our simulation platform.The results show that the oscillation of head's orientation is inhibited effectively,and the proposed method has strong adaptation to environment and CPG parameters changes. 展开更多
关键词 underwater snake-like robot CPG-based control scheme with head-controller orientation stability of head
在线阅读 下载PDF
特殊工况下防止给水泵汽蚀余量不足的除氧器水位控制方法研究
18
作者 程嘉其 王俊洋 +1 位作者 李韩亮 周康伟 《发电设备》 2026年第1期19-25,共7页
针对特殊工况下(如凝结水系统事故状态或者凝结水节流配合机组一次调频)除氧器液位降低的现象,盲目地快速补充凝结水易导致除氧器压力快速下降,进而造成给水泵入口汽蚀余量不足的问题。通过简化除氧器暂态质量‒能量平衡计算模型,得出防... 针对特殊工况下(如凝结水系统事故状态或者凝结水节流配合机组一次调频)除氧器液位降低的现象,盲目地快速补充凝结水易导致除氧器压力快速下降,进而造成给水泵入口汽蚀余量不足的问题。通过简化除氧器暂态质量‒能量平衡计算模型,得出防止给水泵汽蚀余量不足所允许的最大凝结水流量保守值的计算公式。使用设计参数的计算结果符合除氧器仿真建模、除氧器暂态计算的参数变化规律。依此提出通过限制凝结水流量来防止给水泵汽蚀余量不足的除氧器水位控制方法,经实验验证该方法能保证给水泵汽蚀余量始终满足要求。 展开更多
关键词 除氧器水位控制 除氧器暂态 给水泵 汽蚀余量 凝结水流量
在线阅读 下载PDF
基于NESO的改进非奇异终端滑模船舶航向控制
19
作者 常雨芳 王澳黎 +2 位作者 夏亚平 严怀成 黄文聪 《船舶力学》 北大核心 2025年第12期1895-1905,共11页
针对船舶航行过程航向易受外界环境扰动问题,本文提出一种基于非线性扩张状态观测器的改进非奇异终端滑模控制策略。首先,建立船舶航向系统非线性数学模型,设计了基于双曲正切函数的非线性扩张状态观测器,对船舶航行过程受到的外界扰动... 针对船舶航行过程航向易受外界环境扰动问题,本文提出一种基于非线性扩张状态观测器的改进非奇异终端滑模控制策略。首先,建立船舶航向系统非线性数学模型,设计了基于双曲正切函数的非线性扩张状态观测器,对船舶航行过程受到的外界扰动进行估计,并进行前馈补偿;然后,引入改进非奇异终端滑模面和双幂次趋近律,设计了改进非奇异终端滑模控制律,降低了滑模控制律抖振,提高了滑模控制律收敛速度,并将非线性扩张状态观测器和改进非奇异终端滑模控制律结合构成复合控制律;最后,基于李雅普诺夫稳定性理论对控制律的稳定性进行了分析。仿真结果表明,所提出的控制策略能有效提高船舶航向控制系统的跟踪性能和鲁棒性。 展开更多
关键词 船舶 船舶航向控制 非奇异终端滑模控制 非线性扩张状态观测器 鲁棒性
在线阅读 下载PDF
The Role of a Novel Discrete-Time MRAC Based Motion Cueing on Loss of Control at a Hexapod Driving Simulator
20
作者 B. Aykent D. Paillot +2 位作者 F. Merienne C. Guillet A. Kemeny 《Intelligent Control and Automation》 2015年第1期84-102,共19页
The objective of this paper is to present the advantages of Model reference adaptive control (MRAC) motion cueing algorithm against the classical motion cueing algorithm in terms of biomechanical reactions of the part... The objective of this paper is to present the advantages of Model reference adaptive control (MRAC) motion cueing algorithm against the classical motion cueing algorithm in terms of biomechanical reactions of the participants during the critical maneuvers like chicane in driving simulator real-time. This study proposes a method and an experimental validation to analyze the vestibular and neuromuscular dynamics responses of the drivers with respect to the type of the control used at the hexapod driving simulator. For each situation, the EMG (electromyography) data were registered from arm muscles of the drivers (flexor carpi radialis, brachioradialis). In addition, the roll velocity perception thresholds (RVT) and roll velocities (RV) were computed from the real-time vestibular level measurements from the drivers via a motion-tracking sensor. In order to process the data of the EMG and RVT, Pearson’s correlation and a two-way ANOVA with a significance level of 0.05 were assigned. Moreover, the relationships of arm muscle power and roll velocity with vehicle CG (center of gravity) lateral displacement were analyzed in order to assess the agility/alertness level of the drivers as well as the vehicle loss of control characteristics with a confidence interval of 95%. The results showed that the MRAC algorithm avoided the loss of adhesion, loss of control (LOA, LOC) more reasonably compared to the classical motion cueing algorithm. According to our findings, the LOA avoidance decreased the neuromuscular-visual cues level conflict with MRAC algorithm. It also revealed that the neuromuscular-vehicle dynamics conflict has influence on visuo-vestibular conflict;however, the visuo-vestibular cue conflict does not influence the neuromuscular-vehicle dynamics interactions. 展开更多
关键词 Driving Simulator EMG Analysis Model Reference Adaptive control DISCRETE-TIME control Loss of control head Dynamics
暂未订购
上一页 1 2 78 下一页 到第
使用帮助 返回顶部