期刊文献+
共找到918篇文章
< 1 2 46 >
每页显示 20 50 100
Observer-based H_∞ control over packet dropping networks 被引量:1
1
作者 Zhang Dongmei Wang Xingang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2008年第6期1215-1225,共11页
A new controller design problem of networked control systems with packet dropping is proposed. Depending on the place that the observer is put in the system, the network control systems with packet dropping are modele... A new controller design problem of networked control systems with packet dropping is proposed. Depending on the place that the observer is put in the system, the network control systems with packet dropping are modeled as stochastic systems with the random variables satisfying the Bernoulli random binary distribution. The observer-based controller is designed to stabilize the networked system in the sense of mean square, and the prescribed H∞ disturbance attenuation level is achieved. The controller design problem is formulated as the feasibility of the convex optimization problem, which can be solved by a linear matrix inequality (LMI) approach. Numerical examples illustrate the effectiveness of the proposed methods. 展开更多
关键词 networked control systems packet dropping linear matrix inequality
在线阅读 下载PDF
Effect of Instant Controlled Pressure Drop Process Coupled to Drying and Freezing on Antioxidant Activity of Green “Poblano” Pepper (<i>Capsicum annuum</i>L.)
2
作者 Carmen Téllez-Pérez Anaberta Cardador-Martínez +3 位作者 Sabah Mounir José Gerardo Montejano-Gaitán Vaclav Sobolik Karim Allaf 《Food and Nutrition Sciences》 2013年第3期321-334,共14页
Different food operations have been intensified through assisting them by instant controlled pressure drop DIC treatment. Such processes should be defined in order to preserve the main nutritional and sensorial conten... Different food operations have been intensified through assisting them by instant controlled pressure drop DIC treatment. Such processes should be defined in order to preserve the main nutritional and sensorial contents of the raw material. The present paper is dedicated to study the evolution of the main bioactive compounds (total phenolics and flavonoids) and functional properties such as the antioxidant activity of processed samples in the case of Green “Poblano” Pepper (Capsicum annuum L.). Results issued from DIC-assisted hot air drying, and DIC-assisted freezing, allowed to identifying the impact of DIC studied operating parameters, which were the saturated steam pressure and the processing time, and the best DIC treatment correlated with the considered operation. 展开更多
关键词 Instant controlled Pressure drop CAPSICUM Phenols Flavonoids Antioxidant Activity DRYING FREEZING
暂未订购
Towards Include Preservation of Vitamins in Fenugreek and Carob Seeds by the Instant Controlled Pressure-Drop Process (DIC Process)
3
作者 Dalel Melki Lassaad Hedhili +3 位作者 Lamia Hamrouni Mohamed Negm Bassem Jamoussi Karim Allaf 《Food and Nutrition Sciences》 2018年第3期191-207,共17页
Fenugreek and carob seed were germinated in the dark for 4 days and 15 days respectively. The two species are rich in vitamins A, B1, B3, B8. Germination promotes the increase in their concentrations. To ensure preser... Fenugreek and carob seed were germinated in the dark for 4 days and 15 days respectively. The two species are rich in vitamins A, B1, B3, B8. Germination promotes the increase in their concentrations. To ensure preservation and increased bioavailability of the vitamins, it is necessary to apply a DIC of 30s to 400 kPa making it possible to support the cellular expansion and the decontamination of germinated seeds. Vitamin A content in germinated carob seed increased by 82.54%, which is not the case for fenugreek. A decrease in vitamin A concentration of 4 μg/100 g of dry matter. DIC increase vitamin B1, B3 and B8 in germinated fenugreek seeds. A slight decrease of B vitamins in germinated carob seed after treatment with DIC has been noticed. This loss can be explained by the low bioavailability caused mainly by the botanical structures of the seeds. 展开更多
关键词 FENUGREEK CAROB Seed Germination PRESERVATION Bioavailability Vitamin INSTANT controlled Pressure drop (DIC)
暂未订购
Transverse thickness difference control technology for non-oriented silicon steel
4
作者 LI Hongmei LI Shanqing +4 位作者 WANG Bo ZENG Jianfeng JIN Guo DUAN Mingnan ZHOU Yi 《Baosteel Technical Research》 CAS 2013年第1期20-23,共4页
Transverse thickness difference is an important quality index of non-oriented silicon steel strips. In order to fulfill users' accuracy requirements on the transverse thickness of silicon steel and improve the produc... Transverse thickness difference is an important quality index of non-oriented silicon steel strips. In order to fulfill users' accuracy requirements on the transverse thickness of silicon steel and improve the production yield, the factors influencing transverse thickness difference were analyzed. Then the work roll shape, control strategy and incoming hot-rolled strips were optimized. Since the optimization measures were implemented in the actual production, the thickness difference of non-oriented silicon steel has been reduced greatly and fulfilled the requirements placed by users. These measures have achieved remarkable effects. 展开更多
关键词 cold rolling transverse thickness difference non-oriented silicon steel roll shape edge drop control strategy
在线阅读 下载PDF
基于VAE-GRU的风电逐步惯性控制二次频率跌落抑制方法
5
作者 陈俊全 杨福 +3 位作者 蒲清昕 陈以欣 安甦 马覃峰 《黑龙江科技大学学报》 2026年第1期129-137,共9页
为提升高风电渗透率电网的频率稳定性与逐步惯性控制SIC参数自适应性,针对功率恢复阶段二次频率跌落的核心问题,采用变分自编码器与门控循环单元融合架构,提出一种结合灰狼优化算法样本生成、变分自编码器非线性特征提取与降噪、门控循... 为提升高风电渗透率电网的频率稳定性与逐步惯性控制SIC参数自适应性,针对功率恢复阶段二次频率跌落的核心问题,采用变分自编码器与门控循环单元融合架构,提出一种结合灰狼优化算法样本生成、变分自编码器非线性特征提取与降噪、门控循环单元动态映射建模的风电调频优化控制方法。通过改进IEEE39节点系统构建仿真模型,验证所提方法的抑制效果与鲁棒性。结果表明:相较于传统智能方法,文中方法控制参数预测的关键误差指标最大降低53.3%,在5~25 d B噪声环境下综合性能指标稳定高于0.85,25%数据缺失场景下仍保持0.7以上评分,系统频率二次跌落幅度显著减小,为高比例风电并网系统提供了兼具自适应与抗干扰能力的调频解决方案。 展开更多
关键词 风电渗透率 逐步惯性控制 二次频率跌落 变分自编码器 门控循环单元
在线阅读 下载PDF
含构网型直驱风机的电力系统暂态功角稳定性分析与控制策略 被引量:1
6
作者 韩平平 熊瑶 +2 位作者 吴红斌 陈鹏飞 董玮 《电力自动化设备》 北大核心 2025年第9期70-78,共9页
随着新型电力系统的发展,构网型直驱风机(GFM-PMSG)的应用更加广泛,但也改变了电力系统的功角稳定特性。为此,基于扩展等面积法(EEAC),分析了含GFM-PMSG的电力系统的暂态稳定性机理,并提出了一种适用于多机系统的改进GFM-PMSG暂态控制... 随着新型电力系统的发展,构网型直驱风机(GFM-PMSG)的应用更加广泛,但也改变了电力系统的功角稳定特性。为此,基于扩展等面积法(EEAC),分析了含GFM-PMSG的电力系统的暂态稳定性机理,并提出了一种适用于多机系统的改进GFM-PMSG暂态控制策略。构建了含风机的双机系统等效转子运动方程,得到风机并网对同步机之间功角特性的影响主要取决于其有功外特性的结论,并考虑多时间尺度特性,分析了GFM-PMSG的有功外特性;基于EEAC分析了考虑阻尼系数时GFM-PMSG接入对系统同步机之间功角稳定性的影响机理、GFM-PMSG和同步机之间的暂态功角稳定机理及控制参数的影响;提出了一种改进的GFMPMSG暂态控制策略,改善了含GFM-PMSG的电力系统的暂态功角稳定性;在PSCAD/EMTDC中搭建扩展双机系统仿真模型进行对比分析,验证所提策略的有效性。 展开更多
关键词 暂态功角稳定性 构网型直驱风机 电力系统 EEAC 电网电压跌落 暂态控制策略
在线阅读 下载PDF
Rectangular Section Control Technology for Silicon Steel Rolling 被引量:5
7
作者 Xiao-chen WANG Quan YANG You-zhao SUN 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2015年第3期185-191,共7页
Rectangular section control technology (RSCT) was introduced to achieve high-precision profile control during silicon steel rolling. The RSCT principle and method were designed, and the whole RSCT control strategy w... Rectangular section control technology (RSCT) was introduced to achieve high-precision profile control during silicon steel rolling. The RSCT principle and method were designed, and the whole RSCT control strategy was developed. Specifically, RSCT included roll contour design, roiling technology optimization, and control strategy development, aiming at both hot strip mills (HSMs) and cold strip mills (CSMs). Firstly, through the high-performance variable crown (HVC) work roll optimization design in the upper-stream stands and the limited shifting technology for schedule-free rolling in the downstream stands of HSMs, a hot strip with a stable crown and limited wedge, :local spot, and single wave was obtained, which was suitable for cold rolling. Secondly, an approximately rectangular section was obtained by edge varying contact (EVC) work roll contour design, edge-drop setting control, and. closed loop control in the upper-stream, stands of CSMs. Moreover, complex-mode flatness control was realized by coordinating multiple shape-control methods in the downstream stands of CSMs. In addition, the RSCT approach was applied in several silicon-steel production plants, where an outsicanding performance and remarkable economic benefits were observed. 展开更多
关键词 silicon steel rectangular section control technology hot rolling cold rolling edge drop
原文传递
Adaptive Terminal-Modality-Based Joint Call Admission Control for Heterogeneous Cellular Networks 被引量:1
8
作者 Mahmoud M. Badawy Salman A. AlQahtani 《International Journal of Communications, Network and System Sciences》 2013年第9期395-406,共12页
The coexistence of different Radio Access Technologies (RATs) requires a need for Common Radio Resource Management (CRRM) to support the provision of Quality of Service (QoS) and the efficient utilization of radio res... The coexistence of different Radio Access Technologies (RATs) requires a need for Common Radio Resource Management (CRRM) to support the provision of Quality of Service (QoS) and the efficient utilization of radio resources. The provision of QoS is an important and challenging issue in the design of integrated services packet networks. Call admission control (CAC) is an integral part of the problem. Clearly, without CAC, providing QoS guarantees will be impossible. There is unfairness in allocation of radio resources among heterogeneous mobile terminals in heterogeneous wireless networks. In this paper, an Adaptive-Terminal Modality-Based Joint Call Admission Control (ATJCAC) algorithm is proposed to enhance connection-level QoS and reduce call blocking/dropping probability. The proposed ATJCAC algorithm makes call admission decisions based on mobile terminal modality (capability), network load, adaptive the bandwidth of ongoing call and radio access technology (RAT) terminal support index. Simulation results show that the proposed ATJCAC scheme reduces call blocking/dropping probability. 展开更多
关键词 CALL ADMISSION control CALL BLOCKING CALL dropPING Next Generation Wireless Network (NGWN) RAT Selection Approaches
在线阅读 下载PDF
不同频次0.01%阿托品滴眼液控制青少年近视对眼表的影响 被引量:1
9
作者 许琦彬 李秋实 +1 位作者 魏佳敏 戴红梅 《中国临床药理学与治疗学》 北大核心 2025年第2期238-243,共6页
目的:评估不同频次0.01%阿托品滴眼液控制青少年近视对眼表的影响。方法:本研究共招募84名青少年近视患者。随机分配入组予以不同频次(早起组、晚睡组、早晚组)0.01%阿托品滴眼液治疗,观察治疗期间眼部和全身不良反应,并在治疗前和治疗... 目的:评估不同频次0.01%阿托品滴眼液控制青少年近视对眼表的影响。方法:本研究共招募84名青少年近视患者。随机分配入组予以不同频次(早起组、晚睡组、早晚组)0.01%阿托品滴眼液治疗,观察治疗期间眼部和全身不良反应,并在治疗前和治疗后6个月,检查等效球镜度数(SER)、眼轴(AX),通过眼表疾病指数(OSDI)问卷、Keratograph 5M测量泪河高度(TMH)、非侵入式首次泪膜破裂时间(NifBUT)、非侵入性平均泪膜破裂时间(NiaBUT)、睑板腺萎缩评分(MaS)。结果:0.01%阿托品滴眼液治疗6个月内,所有不良反应症状均较轻微且很少发生。只有1例有全身反应,在给药后出现暂时性口干;有6名患者在给药后有眼痒、眼干等不适;早起组和早起晚睡组出现的眼部反应畏光、看近模糊较晚睡组多,但三组之间无统计学差异(P>0.05)。与治疗前相比,三组治疗6个月后,SER、AX有统计学差异(P<0.05);早起组患者OSDI评分(P=0.656)、TMH值(P=0.362)、NifBUT(P=0.510)、NiaBUT(P=0.700)、MaS(P=0.846)均未发生显著变化;晚睡组患者OSDI评分(P=0.429)、TMH值(P=0.462)、NifBUT(P=0.462)、NiaBUT(P=0.598)、MaS(P=0.351)均未发生显著变化;早晚组患者OSDI评分(P=0.457)、TMH值(P=0.748)、NifBUT(P=0.197)、NiaBUT(P=0.070)、MaS(P=0.802)均未发生显著变化。结论:不同频次0.01%阿托品滴眼液控制青少年近视6个月后,眼表无显著影响。 展开更多
关键词 0.01%阿托品滴眼液 眼表 青少年 近视控制
暂未订购
On Line Measurement of Reactivity Worth of TRIGA Mark-II Research Reactor Control Rods
10
作者 Nusrat Jahan Mamunur M. Rashid +3 位作者 F. Ahmed M. G. S. Islam M. Aliuzzaman S. M. A. Islam 《Journal of Modern Physics》 2011年第9期1024-1029,共6页
The reactivity worth measurement system for control rods of the TRIGA MARK-II research reactor of Bangladesh has been design and developed. The theory of the kinetic technique of measuring reactivity has been used by ... The reactivity worth measurement system for control rods of the TRIGA MARK-II research reactor of Bangladesh has been design and developed. The theory of the kinetic technique of measuring reactivity has been used by this measurement system. The system comprises of indigenous hardware and software for online acquisition of neutron flux signals from reactor console and then computes the reactivity worth accordingly. Here for the TRIGA MARK-II research reactor, the reactivity measurement system was implemented with a dedicated circuit assembly and a conventional personal computer. A high-level Visual Basic real-time programming has been developed for data acquisition, reactivity calculation, online display (numerically as well as graphically), saving data, etc. To measure reactivity worth of TRIGA reactor control rods the rod drop experimental technique has been adopted. The results of tests experiments, carried out with the rod drop method for measuring various reactivity worth of control rods have been presented in the paper. A comparison between this results with the results using period method and that of computation method, demonstrated that the response of this reactivity measurement system is fast enough to monitor and measure the safety-related reactivity and power excursions in the reactor. 展开更多
关键词 REACTIVITY WORTH Measurement control ROD Kinetic ROD drop Visual Basic
暂未订购
耦合磁流变与液压机器人关节设计及冲击抑制
11
作者 杨坤全 马佰周 +1 位作者 余春梅 黄惠 《机械设计与制造》 北大核心 2025年第8期332-339,349,共9页
液压机器人足端与地面接触时容易产生较大的碰撞冲击,其会导致零部件受损,严重影响足式机器人使用寿命。针对于此,这里提出了将磁流变阻尼器串联于液压驱动关节实现一体化的减振新方法。首先,以足端可达面积最大为目标,对液压足式机器... 液压机器人足端与地面接触时容易产生较大的碰撞冲击,其会导致零部件受损,严重影响足式机器人使用寿命。针对于此,这里提出了将磁流变阻尼器串联于液压驱动关节实现一体化的减振新方法。首先,以足端可达面积最大为目标,对液压足式机器人腿部结构进行优化,确定腿节长度、摆角及驱动器尺寸。其次,依据垂落工况设计磁流变阻尼器,并将其通过共用活塞杆的方式与液压作动器串联共同形成液压阻尼作动器。然后,依据单腿垂落冲击工况设计模糊控制器,进而减少冲击后的活塞杆位移误差。最后,通过单腿垂落冲击试验知:串有磁流变阻尼器的液压作动器对足式机器人具有明显的抗冲击效果,致使机械腿动态误差最小。 展开更多
关键词 液压足式机器人 磁流变阻尼器 液压阻尼作动器 垂落冲击 模糊控制器
在线阅读 下载PDF
Control Rod Calibration and Worth Calculation for Optimized Power Reactor 1000 (OPR-1000) Using Core Simulator OPR1000 被引量:1
12
作者 Nguyen An Son Nguyen Duc Hoa +2 位作者 Tran Trung Nguyen Tran Quoc Tuan Osvaldo Camueje Raul 《World Journal of Nuclear Science and Technology》 2017年第1期15-23,共9页
Control rod is used to change the power in nuclear reactor.?Certainly, the core at any moment can be made subcritical condition and shut downs when occurring?to emergency instance in the core. The rod is grouped based... Control rod is used to change the power in nuclear reactor.?Certainly, the core at any moment can be made subcritical condition and shut downs when occurring?to emergency instance in the core. The rod is grouped based?on their function and located at different places in the core where their feature is maximized.?Two methods of control rod calibration are the asymptotic period method and the rod-drop method, which were applied in this experiment. In the first method, the reactor is made supcritical by inserting the control rod to be calibrated a certain level. The rod drop method is to determine the subcritical;at the critical state, the rod to be calibrated is dropped into the core, and the resulting decay of neutron flux is observed and related to the reactivity. In this paper, the regulating rod will be calibrated according to the reactivity in OPR-1000 that corresponds to a certain control rod insert or withdraw, and the reactivity in power reactor depends?on the integral and differential control rod group too. The core simulator OPR1000 is used to test those methods. 展开更多
关键词 control ROD The ASYMPTOTIC Period METHOD The Rod-drop METHOD CORE SIMULATOR OPR1000
暂未订购
自适应虚拟阻抗的微电网二次补偿控制策略研究
13
作者 章宝歌 吕雄 +2 位作者 田浩 任勇全 崔福红 《哈尔滨工程大学学报》 北大核心 2025年第6期1179-1186,共8页
微电网中逆变器输出线路阻抗的差异会影响传统下垂控制的效果,导致负荷分配精度降低和电压跌落增大。针对目前传统下垂控制的不足,本文提出一种基于自适应虚拟阻抗的二次补偿控制策略。利用逆变器无功功率输出作为失配项,设计了自适应... 微电网中逆变器输出线路阻抗的差异会影响传统下垂控制的效果,导致负荷分配精度降低和电压跌落增大。针对目前传统下垂控制的不足,本文提出一种基于自适应虚拟阻抗的二次补偿控制策略。利用逆变器无功功率输出作为失配项,设计了自适应调整虚拟阻抗,可在逆变器输出线路阻抗不匹配的状况下,实现无功功率精准校正。对于由功率均分所造成的频率偏移和电压跌落现象,利用各分布式电源之间输出的频率和电压调整量作为下垂控制电压和频率的补偿量,设计了二次频率和电压恢复的补偿控制策略,实现频率和电压与原设定值同步,弥补在系统稳定运行时的频率偏移和电压跌落,提高了微电网的电能质量。在Matlab/Simulink中搭建孤岛微电网多台逆变器并联仿真模型,通过仿真结果分析验证了本文控制策略的有效性、可行性和可拓展性。 展开更多
关键词 分布式电源 下垂控制 自适应虚拟阻抗 功率校正 频率偏移 电压跌落 二次补偿控制 电能质量
在线阅读 下载PDF
低浓度阿托品滴眼液防控儿童近视的应用效果 被引量:1
14
作者 林春堤 熊永强 +2 位作者 童林利 林琳 吕月娥 《中国现代药物应用》 2025年第22期99-101,共3页
目的研究低浓度阿托品滴眼液用于儿童近视防控中的效果。方法选择近视儿童100例作为研究对象,用随机数表法分为对照组及观察组,每组50例。对照组实施视觉训练,观察组在对照组基础上增加低浓度(0.01%)阿托品滴眼液治疗。比较两组患儿的... 目的研究低浓度阿托品滴眼液用于儿童近视防控中的效果。方法选择近视儿童100例作为研究对象,用随机数表法分为对照组及观察组,每组50例。对照组实施视觉训练,观察组在对照组基础上增加低浓度(0.01%)阿托品滴眼液治疗。比较两组患儿的屈光度、眼轴长度、眼压。结果治疗后,两组屈光度优于本组治疗前,且观察组屈光度(-2.46±0.10)优于对照组的(-2.31±0.12),有显著性差异(P<0.05)。治疗后,两组眼轴长度短于本组治疗前,且观察组眼轴长度(21.04±1.08)mm短于对照组的(22.31±1.24)mm,有显著性差异(P<0.05)。治疗后,两组眼压高于本组治疗前,且观察组眼压(17.95±1.50)mm Hg(1 mm Hg=0.133 kPa)高于对照组的(16.92±1.63)mm Hg,有显著性差异(P<0.05)。结论低浓度阿托品滴眼液更有利于儿童近视的防控,对于改善患儿的眼压、眼轴长度和屈光度有积极意义,配合实施视觉训练有理想效果,临床上值得推广和应用。 展开更多
关键词 低浓度 阿托品滴眼液 视觉训练 儿童 近视 防控效果
暂未订购
基于综合补偿的改进下垂控制研究
15
作者 巫付专 尹清森 +2 位作者 朱永胜 张一鸣 梁铭心 《中原工学院学报》 2025年第5期21-30,共10页
对于在低压微电网中采用下垂控制的并网逆变器,由于下垂控制特性与虚拟电感的作用,当电网频率下降时,系统输出的功率因数降低且冲击电流增大。针对该问题,首先,阐述了系统输出的无功功率随电网频率变化而波动的原因,提出了一种基于综合... 对于在低压微电网中采用下垂控制的并网逆变器,由于下垂控制特性与虚拟电感的作用,当电网频率下降时,系统输出的功率因数降低且冲击电流增大。针对该问题,首先,阐述了系统输出的无功功率随电网频率变化而波动的原因,提出了一种基于综合补偿的改进下垂控制。改进后的下垂控制能够动态地调整逆变器输出端电压的幅值与相位,在提高系统输出功率因数的同时减小了电网频率降低时系统的冲击电流。其次,通过建立并网逆变器的小信号模型对基于综合补偿的改进下垂控制进行了稳定性分析。最后,通过仿真和实验分析验证了基于综合补偿的改进下垂控制能有效抑制电网频率发生波动时输出的冲击电流增大、功率因数降低。研究提高了系统的效率,降低了系统的损耗。 展开更多
关键词 并网逆变器 下垂控制 综合补偿 功率因数 小信号分析
在线阅读 下载PDF
杨梅内生芽孢杆菌对采前落果和肉葱病的防效评价
16
作者 陈官菊 梁秀美 +6 位作者 荀倩 孔凡轩 宋洋 何如意 单琳雯 郭秀珠 夏海涛 《中国果树》 2025年第11期100-103,共4页
杨梅采前落果和肉葱病严重影响果实产量和品质,而现有化学防控手段存在药害及残留风险。基于杨梅枝干内生芽孢杆菌研制复合微生物菌剂,评估其对丁岙梅采前落果和肉葱病的防控效果。田间试验结果表明:1×10^(5)cfu/mL和5×10^(4)... 杨梅采前落果和肉葱病严重影响果实产量和品质,而现有化学防控手段存在药害及残留风险。基于杨梅枝干内生芽孢杆菌研制复合微生物菌剂,评估其对丁岙梅采前落果和肉葱病的防控效果。田间试验结果表明:1×10^(5)cfu/mL和5×10^(4)cfu/mL复合微生物菌剂处理落果防控效果(66.58%、66.34%)与375 mg/L8%对氯苯氧乙酸钠处理(67.83%)相当,且无药害风险;同时,1×10^(5)cfu/mL复合微生物菌剂处理对肉葱病的防控效果(66.90%)显著优于375 mg/L 8%对氯苯氧乙酸钠处理(57.18%),应用前景较好。 展开更多
关键词 杨梅 采前落果 肉葱病 芽孢杆菌 防控效果
原文传递
0.02%阿托品滴眼液治疗青少年近距离工作引起的暂时性近视的有效性和安全性
17
作者 郭雷 陶军 +4 位作者 魏智媛 于洪波 才文卓 郭子奇 华瑞 《中国医科大学学报》 北大核心 2025年第10期946-950,共5页
目的探讨0.02%阿托品滴眼液治疗青少年近距离工作引起的暂时性近视(NITM)的有效性和安全性。方法将131例NITM青少年随机分为试验组(64例)和对照组(67例),试验组使用0.02%阿托品滴眼液,对照组使用0.02%阿托品滴眼液溶剂,观察用药前以及用... 目的探讨0.02%阿托品滴眼液治疗青少年近距离工作引起的暂时性近视(NITM)的有效性和安全性。方法将131例NITM青少年随机分为试验组(64例)和对照组(67例),试验组使用0.02%阿托品滴眼液,对照组使用0.02%阿托品滴眼液溶剂,观察用药前以及用药14 d和30 d时NITM初始值的变化,观察眼压、调节幅度的变化,记录畏光和视近物障碍等并发症的发生情况。结果2组比较,基线时NITM初始值无统计学差异(P>0.05)。用药14 d和30 d时,试验组NITM初始值与基线相比显著降低(P<0.05),用药14 d、30 d与基线的差值分别为(0.31±0.20)D和(0.30±0.16)D,明显大于对照组的(0.21±0.98)D和(0.20±0.18)D(P<0.001)。试验组NITM治疗有效率为84.4%,显著高于对照组(29.9%)。用药30 d后,试验组未发生严重的全身和眼部不良反应,主要的不良反应为轻度畏光。结论应用0.02%阿托品滴眼液30 d,可有效降低近视青少年的NITM初始值,无严重并发症发生,耐受性好,更长期应用不同浓度的阿托品滴眼液治疗NITM的临床试验具有可行性。 展开更多
关键词 0.02%阿托品滴眼液 近距离工作引起的暂时性近视 随机对照试验 有效性 安全性
暂未订购
增强LVRT能力的逆变器多电能质量优化预测控制
18
作者 汪海宁 冯博文 +3 位作者 耿将 谢缔 汪亮亮 张鹏 《太阳能学报》 北大核心 2025年第4期91-102,共12页
提出一种适应三电平逆变器低电压穿越(LVRT)的多目标模型预测电流控制策略,无需电流正负序分离和滤波电网电压前馈,在跌落过程中不会出现过电流;给出αβ轴下功率/电流质量优化的指令电流计算通式,通过调整修正系数矩阵,实现功率波动、... 提出一种适应三电平逆变器低电压穿越(LVRT)的多目标模型预测电流控制策略,无需电流正负序分离和滤波电网电压前馈,在跌落过程中不会出现过电流;给出αβ轴下功率/电流质量优化的指令电流计算通式,通过调整修正系数矩阵,实现功率波动、负序电流和谐波电流之间的协调控制,提高逆变器在LVRT过程中的动态响应及多电能质量优化能力。仿真和实验验证所提方法动态响应的优越性。 展开更多
关键词 三电平 逆变器 模型预测控制 电能质量 电压跌落 低电压穿越
原文传递
基于有功-无功联合控制的构网型变流器暂态稳定性提升方法 被引量:2
19
作者 夏向阳 赵晓悦 +3 位作者 梁军 罗文广 陈贵全 郑汉锋 《电力系统自动化》 北大核心 2025年第11期114-125,共12页
针对构网型变流器在电网对称故障下的暂态功角失稳和故障电流越限问题,提出了一种结合二阶滑模控制与电压自适应调节的联合控制方法。首先,在构网型变流器有功功率-频率环中引入改进型积分滑模面并构造李雅普诺夫函数,依据稳定性判据设... 针对构网型变流器在电网对称故障下的暂态功角失稳和故障电流越限问题,提出了一种结合二阶滑模控制与电压自适应调节的联合控制方法。首先,在构网型变流器有功功率-频率环中引入改进型积分滑模面并构造李雅普诺夫函数,依据稳定性判据设计输出功率控制律,在计及电网相位变化的同时严格限制故障期间变流器输出功角波动。其次,采用无功功率-电压环切换控制以提供稳定的无功功率,支撑并网点电压,同时确保故障电流维持在安全阈值之内。最后,仿真与实验结果表明:在电网电压严重跌落并伴随相位突变的情况下,所提策略仍能有效提升构网型变流器故障穿越能力及故障切除后的恢复速率,其精细化主动支撑特性也同样适用于高低压穿越的复杂工况。 展开更多
关键词 构网型变流器 暂态稳定性 二阶滑模控制 故障限流 电压跌落 相位突变
在线阅读 下载PDF
汽水分离器用套筒调节阀的高压差空化特性研究 被引量:1
20
作者 刘育栋 罗陆生 +3 位作者 盛况 李文庆 金志江 钱锦远 《阀门》 2025年第8期809-817,I0003,共10页
在核电、石化等领域的压力管道系统中,套筒调节阀面临高温高压差下的空化与闪蒸挑战。本文以汽水分离器用角形套筒高温调节阀为研究对象,采用数值模拟方法探讨其在高压差工况下的流量系数曲线、流动特性以及空化闪蒸机制。结果表明:流... 在核电、石化等领域的压力管道系统中,套筒调节阀面临高温高压差下的空化与闪蒸挑战。本文以汽水分离器用角形套筒高温调节阀为研究对象,采用数值模拟方法探讨其在高压差工况下的流量系数曲线、流动特性以及空化闪蒸机制。结果表明:流量系数曲线呈分段变化———开度10%~60%时迷宫流道主导线性增长,开度大于60%后多孔流道引发等百分比特性跃升。此外,在三类典型工况下,过热蒸汽工况中迷宫流道实现阶梯降压,过冷水空化工况下仅在迷宫流道末端低压漩涡区触发局部空化,过冷水闪蒸工况则因出口压力持续低于饱和蒸汽压而导致闪蒸现象。本研究为套筒调节阀在复杂工况下的空化抑制(优化漩涡区结构)和闪蒸工况选型(控制出口压力阈值)提供一定的参考价值。 展开更多
关键词 高压差 套筒调节阀 空化 闪蒸
在线阅读 下载PDF
上一页 1 2 46 下一页 到第
使用帮助 返回顶部