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Adaptive output regulation of uncertain nonlinear systems with unknown control directions
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作者 Jingyu CHEN Zhenhong LI Zhengtao DING 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第8期206-208,共3页
Dear editor, The output regulation problem for nonlinear systems with unknown exosystems has been an important research topic over the last few decades [1]. The early results commonly assume that the sign of the high-... Dear editor, The output regulation problem for nonlinear systems with unknown exosystems has been an important research topic over the last few decades [1]. The early results commonly assume that the sign of the high-frequency gain is known. It is shown [2] that a nonlinear system can be transformed into a special observer form under geometrie coordinatefree conditions. In this case, with a known control direction, the problem can be solved by a robust control method such as high-gain feedback. However, this method is not applicable when the high-frequency gain sign is unknown. 展开更多
关键词 ADAPTIVE OUTPUT regulation UNCERTAIN nonlinear systems UNKNOWN control DIRECTIONS
我国黄磷及精细磷酸盐生产的困境和发展机遇
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作者 姚之琦 孙志立 问立宁 《磷肥与复肥》 CAS 2019年第11期1-3,共3页
介绍国内黄磷工业及磷酸盐产业、产品链的现状与发展趋势。指出注重绿色环保、高端布局,重点发展精细磷酸盐产品,改变产品同质化、发展差异化质量产品,是未来我国热法黄磷、精细磷酸盐发展的机遇和方向。
关键词 黄磷 磷酸盐 发展 机遇 方向
A framework for investigating the air quality variation characteristics based on the monitoring data: Case study for Beijing during 2013–2016
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作者 Jixian Cui Jianlei Lang +4 位作者 Tian Chen Shushuai Mao Shuiyuan Cheng Zhanshan Wang Nianliang Cheng 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第7期225-237,共13页
In this study, an analysis framework based on the regular monitoring data was proposed for investigating the annual/inter-annual air quality variation and the contributions from different factors(i.e., seasons, pollut... In this study, an analysis framework based on the regular monitoring data was proposed for investigating the annual/inter-annual air quality variation and the contributions from different factors(i.e., seasons, pollution periods and airflow directions), through a case study in Beijing from 2013 to 2016. The results showed that the annual mean concentrations(MC) of PM2.5, SO2, NO2 and CO had decreased with annual mean ratios of 7.5%, 28.6%, 4.6%and 15.5% from 2013 to 2016, respectively. Among seasons, the MC in winter contributed the largest fractions(25.8%~46.4%) to the annual MC, and the change of MC in summer contributed most to the inter-annual MC variation(IMCV) of PM2.5 and NO2. For different pollution periods, gradually increase of frequency of S-1(PM2.5, 0~ 75 μg/m3) made S-1 become the largest contributor(28.8%) to the MC of PM2.5 in 2016, it had a negative contribution(-13.1%) to the IMCV of PM2.5;obvious decreases of frequencies of heavily polluted and severely polluted dominated(44.7% and 39.5%) the IMCV of PM2.5. For different airflow directions, the MC of pollutants under the south airflow had the most significant decrease(22.5%~62.5%), and those decrease contributed most to the IMCV of PM2.5(143.3%),SO2(72.0%), NO2(55.5%) and CO(190.3%);the west airflow had negative influences to the IMCV of PM2.5, NO2 and CO. The framework is helpful for further analysis and utilization of the large amounts of monitoring data;and the analysis results can provide scientific supports for the formulation or adjustment of further air pollution mitigation policy. 展开更多
关键词 Monitoring data analysis Air quality variations AIRFLOW DIRECTIONS Pollution PERIODS BEIJING
Perspective on Etiology and Treatment of Bipolar Disorders in China: Clinical Implications and Future Directions
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作者 Zuowei Wang Chen Jun +2 位作者 Kerning Gao Haichen Yang Yiru Fang 《神经科学通报:英文版》 SCIE CAS CSCD 2019年第4期608-612,共5页
Bipolar disorder (BD) is a chronic, recurrent, disabling disease, even when given currently-available pharmacological and psychological treatments. Currently, the etiology and pathogenesis of BD remain unclear. As a c... Bipolar disorder (BD) is a chronic, recurrent, disabling disease, even when given currently-available pharmacological and psychological treatments. Currently, the etiology and pathogenesis of BD remain unclear. As a consequence, patients with BD are frequently unrecognized, misdiagnosed, and inappropriately treated, which often yields a low treatment response and poor outcome. 展开更多
关键词 PERSPECTIVE Future DIRECTIONS BIPOLAR DISORDERS
Special Issue on future directions in plasma nanoscience
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作者 Erik C.Neyts 《化学科学与工程前沿:英文版》 EI CAS CSCD 2019年第2期199-200,共2页
Over the past 20 years,plasma nanoscience has become a mature and vibrant field.It deals with both the fundamental science and applications of low-temperature plasmas,ion beams,lasers,and related approaches and how th... Over the past 20 years,plasma nanoscience has become a mature and vibrant field.It deals with both the fundamental science and applications of low-temperature plasmas,ion beams,lasers,and related approaches and how this relates to the fabrication,synthesis,modification,and integration in and of nanoscale materials,structures and functional devices.The complexity often encountered in research in this field intrinsically calls for both fundamental and applied research,both experimental and theoretical.Plasma nanoscience,therefore,is a highly multidisciplinary field,bringing together researchers from physics,chemistry,medicine,engineering,biochemistry,informatics and more. 展开更多
关键词 SPECIAL ISSUE FUTURE DIRECTIONS PLASMA nanoscience
Hepatocellular carcinoma in non-cirrhotic liver: A comprehensive review 预览
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作者 Aakash Desai Sonia Sandhu +1 位作者 Jin-Ping Lai Dalbir Singh Sandhu 《世界肝病学杂志:英文版(电子版)》 2019年第1期1-18,共18页
Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, which in turns accounts for the sixth most common cancer worldwide. Despite being the 6th most common cancer it is the second leading cau... Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, which in turns accounts for the sixth most common cancer worldwide. Despite being the 6th most common cancer it is the second leading cause of cancer related deaths. HCC typically arises in the background of cirrhosis, however, about 20% of cases can develop in a non-cirrhotic liver. This particular subgroup of HCC generally presents at an advanced stage as surveillance is not performed in a non-cirrhotic liver. HCC in non-cirrhotic patients is clinically silent in its early stages because of lack of symptoms and surveillance imaging; and higher hepatic reserve in this population. Interestingly, F3 fibrosis in non-alcoholic fatty liver disease, hepatitis B virus and hepatitis C virus infections are associated with high risk of developing HCC. Even though considerable progress has been made in the management of this entity, there is a dire need for implementation of surveillance strategies in the patient population at risk, to decrease the disease burden at presentation and improve the prognosis of these patients. This comprehensive review details the epidemiology, risk factors, clinical features, diagnosis and management of HCC in non-cirrhotic patients and provides future directions for research. 展开更多
关键词 HEPATOCELLULAR carcinoma Non-cirrhotic liver HEPATITIS B HEPATITIS C Risk factors Clinical features DIAGNOSTIC MODALITIES Management strategies Future DIRECTIONS
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Vibration-insensitive fiber spool for laser stabilization
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作者 黄军超 汪凌珂 +5 位作者 段怡菲 黄亚峰 叶美凤 李琳 刘亮 李唐 《中国光学快报:英文版》 SCIE EI CAS CSCD 2019年第8期47-51,共5页
Excess frequency noise induced by mechanical vibration is the dominant noise source at low Fourier frequencies in fiber-delay-line stabilized lasers. To resolve this problem, a double-winding fiber spool is designed a... Excess frequency noise induced by mechanical vibration is the dominant noise source at low Fourier frequencies in fiber-delay-line stabilized lasers. To resolve this problem, a double-winding fiber spool is designed and implemented that has ultralow acceleration sensitivity in all spatial directions. By carefully choosing the optimal geometry parameters of the fiber spool, we achieve acceleration sensitivity of 8 × 10^-11/g and 3 × 10^-11/g(g denotes the gravitational acceleration) in axial and radial directions, respectively. 展开更多
关键词 noise VIBRATION DIRECTIONS
Effects of incident wind/wave directions on dynamic response of a SPAR-type floating offshore wind turbine system 预览
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作者 Guoqin Lyu Huiqin Zhang Jiachun Li 《力学学报:英文版》 SCIE EI CAS CSCD 2019年第5期954-963,共10页
As a promising renewable energy,offshore wind energy currently is gaining more attention,by which the economic and efficient operation of floating wind turbine systems is a potential research direction.This study is p... As a promising renewable energy,offshore wind energy currently is gaining more attention,by which the economic and efficient operation of floating wind turbine systems is a potential research direction.This study is primarily devoted to the analysis of dynamic response of the NREL-5 MW reference wind turbine supported by an OC3-Hywind SPAR-type platform using a recompiled code which combines FAST with WAMIT.To verify the reliability of the recompiled code,the free decay motions of a floating wind turbine system in still water are examined with satisfactory results.After that,thirteen scenarios with different angles between wind and wave from 0°to 90°are investigated.The dynamic responses of the turbine system in various degrees of freedom(DOFs)for different incident wind/wave directions are presented in both time and frequency domains via the fast Fourier transform. 展开更多
关键词 Offshore floating wind turbine Dynamic responses SPAR-type wind turbine Distributions of wind and wave directions
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ECONOMICAL DIFFERENCE SCHEME FOR ONE MULTI-DIMENSIONAL NONLINEAR SYSTEM 预览
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作者 Temur JANGVELADZE Zurab KIGURADZE Mikheil GAGOSHIDZE 《数学物理学报:B辑英文版》 SCIE CSCD 2019年第4期971-988,共18页
The multi-dimensional system of nonlinear partial differential equations is considered. In two-dimensional case, this system describes process of vein formation in higher plants. Variable directions finite difference ... The multi-dimensional system of nonlinear partial differential equations is considered. In two-dimensional case, this system describes process of vein formation in higher plants. Variable directions finite difference scheme is constructed. The stability and convergence of that scheme are studied. Numerical experiments are carried out. The appropriate graphical illustrations and tables are given. 展开更多
关键词 System of nonlinear partial differential equations variable DIRECTIONS finite difference scheme stability and CONVERGENCE numerical RESOLUTION
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Epigenetics:Potentials and Challenges in Crop Breeding
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作者 Soodeh Tirnaz Jacqueline Batley 《分子植物:英文版》 SCIE CAS CSCD 2019年第10期1309-1311,共3页
The rapidly increasing global crop demand due to world population growth and changes in diet,combined with the challenges imposed on crop production due to global climate change are highlighting the urgency for improv... The rapidly increasing global crop demand due to world population growth and changes in diet,combined with the challenges imposed on crop production due to global climate change are highlighting the urgency for improving both crop yield and quality.Epigenetics can provide novel directions to drive plant breeding strategies and is rapidly gaining its place among modern crop breeding approaches.Here we discuss the necessity of including epigenetic diversity in crop breeding programs,as visualized in Figure 1. 展开更多
关键词 BREEDING FIGURE DIRECTIONS
倾听EC
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《英语角》 2019年第19期23-23,75共2页
Ⅰ.Directions:Listen to the dialogues and choose the best answer.
关键词 倾听EC DIRECTIONS dialogues
A Primal-dual Interior-point Algorithm for Symmetric Cone Convex Quadratic Programming Based on the Commutative Class Directions
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作者 S.ASADI,H.MANSOURI M. ZANGIABADI 《应用数学学报:英文版》 SCIE CSCD 2019年第2期359-373,共15页
In this paper, we present a neighborhood following primal-dual interior-point algorithm for solving symmetric cone convex quadratic programming problems, where the objective function is a convex quadratic function and... In this paper, we present a neighborhood following primal-dual interior-point algorithm for solving symmetric cone convex quadratic programming problems, where the objective function is a convex quadratic function and the feasible set is the intersection of an affine subspace and a symmetric cone attached to a Euclidean Jordan algebra. The algorithm is based on the [13] broad class of commutative search directions for cone of semidefinite matrices, extended by [18] to arbitrary symmetric cones. Despite the fact that the neighborhood is wider, which allows the iterates move towards optimality with longer steps, the complexity iteration bound remains as the same result of Schmieta and Alizadeh for symmetric cone optimization problems. 展开更多
关键词 INTERIOR-POINT method symmetric cone CONVEX quadratic programming wide NEIGHBORHOOD COMMUTATIVE CLASS DIRECTIONS complexity bound
Current status and future directions of the Tibetan Plateau ecosystem research
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作者 Yangjian Zhang Yixuan Zhu +1 位作者 Junxiang Li Yao Chen 《科学通报:英文版》 SCIE EI CSCD 2019年第7期428-430,共3页
The Tibetan Plateau (TP) encompasses Xizang and Qinghai and parts of northern Yunnan and Sichuan provinces, with a total area of circa 2.6 millions km2. The 2013 satellite data showed that grasslands, forests, wetland... The Tibetan Plateau (TP) encompasses Xizang and Qinghai and parts of northern Yunnan and Sichuan provinces, with a total area of circa 2.6 millions km2. The 2013 satellite data showed that grasslands, forests, wetlands, agricultural lands, and deserts account for 60%, 7.7%, 1.4%, 0.3%, and 30%, respectively, of total TP land (1)Due to its existence in dry, high altitude and cold environments, the TP ecosystem is extremely vulnerable to global climate change and studies on the TP ecosystem can be utilized as a pre-warning for other ecosystems. 展开更多
关键词 Current status and future DIRECTIONS of the TIBETAN PLATEAU ECOSYSTEM research TP
Global practical tracking with prescribed transient performance for inherently nonlinear systems with extremely severe uncertainties
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作者 Fengzhong LI Yungang LIU 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第2期81-96,共16页
This paper considers the global practical tracking for a class of uncertain nonlinear systems.Remarkably,the systems under investigation admit rather inherent nonlinearities,and especially allow arguably the most seve... This paper considers the global practical tracking for a class of uncertain nonlinear systems.Remarkably,the systems under investigation admit rather inherent nonlinearities,and especially allow arguably the most severe uncertainties:unknown control directions and non-parametric uncertainties.Despite this,a refined tracking objective,rather than a reduced one,is sought.That is,not only pre-specified arbitrary tracking accuracy is guaranteed,but also certain prescribed transient performance(e.g.,arrival time and maximum overshoot)is ensured to better meet real applications.To solve the problem,a new tracking scheme is established,crucially introducing delicate time-varying gains to counteract the severe uncertainties and guarantee the prescribed performance.It is shown that the designed controller renders the tracking error to forever evolve within a prescribed performance funnel,through which the desired tracking objective is accomplished for the systems.Particularly,by subtly specifying the funnel,global fixed-time practical tracking(i.e.,that with prescribed arrival time)and semiglobal practical tracking with prescribed maximal overshoot can be achieved for the systems.Moreover,the tracking scheme remains valid in the presence of rather less-restrictive unmodeled dynamics. 展开更多
关键词 nonlinear systems PRACTICAL TRACKING PRESCRIBED transient performance unknown control DIRECTIONS non-param etric UNCERTAINTIES unmodeled dynamics
以发现和解决技术问题为核心提升河北省专利数量和质量 预览
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作者 李惠军 《中国发明与专利》 2018年第6期41-46,共6页
针对企业职工、研究人员、社会公众、在校学生几类群体,围绕技术问题的提出方向进行了探讨,认为应当充分发挥企业在技术创新中的主体作用,围绕企业各环节进行技术创新,制订正确的企业专利战略。充分发挥科研院所和大专院校的先导和支持... 针对企业职工、研究人员、社会公众、在校学生几类群体,围绕技术问题的提出方向进行了探讨,认为应当充分发挥企业在技术创新中的主体作用,围绕企业各环节进行技术创新,制订正确的企业专利战略。充分发挥科研院所和大专院校的先导和支持作用,面向国家重大需求进行创新,通过协同创新扩展新技术的应用领域;创造全社会参与创造的良好氛围,引导在校学生投身发明创造,从日常生活中发现创新目标;对于创新问题,使用创新问题解决工具帮助寻求答案。文中提出了一些新颖创新方向。 展开更多
关键词 技术创新 问题 方向 目标 知识产权
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优质校创建背景下民办高职院校发展的痛点、契机、方向 预览
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作者 顾佳滨 《天津中德应用技术大学学报》 2018年第3期29-33,共5页
建设200所优质专科高等职业院校的目标为民办高职院校的发展提供了新标杆,但纵观当前民办高职院校发展的现状,其在优质校建设的目标中,还存在着很多痛点亟需解决。但随着新《中华人民共和国民办教育促进法》的颁布,无异于给民办高职院... 建设200所优质专科高等职业院校的目标为民办高职院校的发展提供了新标杆,但纵观当前民办高职院校发展的现状,其在优质校建设的目标中,还存在着很多痛点亟需解决。但随着新《中华人民共和国民办教育促进法》的颁布,无异于给民办高职院校以新的发展契机。在此契机下,民办高职院校只有找准方向:明确定位,走内涵发展之路;错位竞争,打造自己的特色;铸造品牌,提升社会服务力;"二元"培养,提升人才竞争力,才能够在优质校创建过程中卓有成效。 展开更多
关键词 优质校创建 民办高职院校 发展方向
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“方向感”带你轻松辨方向——三下“认识东南西北”一课的教学与所得 预览 被引量:1
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作者 曹洁 《科教文汇》 2017年第7期113-114,共2页
“路痴”是与生俱来的吗?科学家们对小老鼠脑中负责辨认方向的细胞进行研究,然后推知人类的方向感是与生俱来的,但会随着后天空间经验的增多而不断完善。这样,对许多人而言,与其说他们没有方向感,不如说是方向感没有被很好地开发、利... “路痴”是与生俱来的吗?科学家们对小老鼠脑中负责辨认方向的细胞进行研究,然后推知人类的方向感是与生俱来的,但会随着后天空间经验的增多而不断完善。这样,对许多人而言,与其说他们没有方向感,不如说是方向感没有被很好地开发、利用。培养小学生的方向感,对其今后的生活工作会带来很多便利。义务教育课程“图形与几何”中专门有一部分内容学习位置与方向。三年级下册《认识东南西北》则是让学生理性地、数学化地去认识东南西北,将生活积累的空间观念进行完善。培养学生的方向感,使他们在生活中轻松地去辨认方向。 展开更多
关键词 方向 方向感 空间观念
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Technology is the best footnote to change life 预览
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作者 Liang Ruili Shen Da 《中国纺织:英文版》 2017年第10期13-15,共3页
<正>In recent years,industrial textile industry undertakes the task for the growth of textile industry well,so it not only becomes one of important directions and main ways for the transformation and upgrade,and... <正>In recent years,industrial textile industry undertakes the task for the growth of textile industry well,so it not only becomes one of important directions and main ways for the transformation and upgrade,and structural adjustment of textile industry,but also turns into the part of national strategic emerging industries and diversified high-tech industry across various fields.Industrial textile industry has made important 展开更多
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中国传统文化融入高校思想政治理论课教学中的思考 预览 被引量:2
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作者 刘芳 《吕梁学院学报》 2017年第1期56-59,共4页
中国传统文化在高校思想政治理论课教学中具有重要的作用。传统文化在融入思政课教学的过程中,既要正确处理两者之间的关系,合理、科学地评价其价值,更要遵循一定的原则和路径选择。
关键词 传统文化 思想政治理论课教学 价值 原则 路径选择
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电力市场下主动配电网运营分析与展望 预览
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作者 杨苹 吕宇桦 +2 位作者 孙宇嫣 康龙云 罗志昭 《科技创新导报》 2017年第23期185-188,共4页
主动配电网能够使低碳可再生能源最大化利用,还能主动调节改善电能质量,因而是现代实现低碳环保的有效途径。主动配电网的主动性和安全性,是动态电价机制下分布式电源能够有效最大化供应给用户的关键因素。本文在总结主动配电网各方... 主动配电网能够使低碳可再生能源最大化利用,还能主动调节改善电能质量,因而是现代实现低碳环保的有效途径。主动配电网的主动性和安全性,是动态电价机制下分布式电源能够有效最大化供应给用户的关键因素。本文在总结主动配电网各方面运营研究和具体工作情况的基础上,分析了主动配电网在电力市场环境下的运营方式调整,提出了主动配电网发展方向的展望。 展开更多
关键词 主动配电网 电力市场 运营分析 展望
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