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Fault tolerant control strategy for modular PWM current source inverter

《能源前沿(英文)》 2023年 第17卷 第2期   页码 228-238 doi: 10.1007/s11708-022-0852-6

摘要: In this paper, a fault-tolerant control method for an input-series output-parallel modular grid-tied pulse-width modulation (PWM) current source inverter is proposed to address the most commonly seen single symmetrical gate-commutated thyristor (SGCT) open-circuit fault problems. This method actively offsets the neutral point of the current space vector to ensure a sinusoidal output of the grid current, and it can achieve the upper limit power of the inverter under the condition of a single SGCT open-circuit fault. In addition, an active damping control method based on grid harmonic current feedback is proposed after analyzing the influence of the transformer ferromagnetic resonance caused by the neutral point offset on the power quality of the grid current. It has been demonstrated that the proposed method effectively suppresses the resonance caused by the transformer and the modified modulation, improving the grid current’s power quality.

关键词: current source converter (CSC)     fault-tolerant control     space vector modulation     active damping     resonance suppression     power quality    

Design and evaluation of control strategies in urban drainage systems in Kunming city

Xin Dong, Senchen Huang, Siyu Zeng

《环境科学与工程前沿(英文)》 2017年 第11卷 第4期 doi: 10.1007/s11783-017-0968-9

摘要: Real time control (RTC) of urban drainage systems (UDSs) is an important measure to reduce combined sewer overflow (CSO) and urban flooding, helping achieve the aims of ‘Sponge City’. Application of RTC requires three main steps: strategy design, simulation-based evaluation and field test. But many of published RTC studies are system-specific, lacking discussions on how to design a strategy step by step. In addition, the existing studies are prone to use hydrologic model to evaluated strategies, but a more precise and dynamic insight into strategy performance is needed. To fill these knowledge gaps, based on a case UDS in Kunming city, a study on RTC strategy design and simulation-based evaluation is performed. Two off-line volume-based RTC strategy design principles, and , are emphasized. Following these principles, a detailed design procedure is shown for the case UDS resulting in three RTC strategies: static, constant and equal filling. The proposed strategies are evaluated based on a hydrodynamic model- Storm Water Management Model (SWMM) - under four typical rainfall events characterized by different return periods (1-year or 0.5 year) and different spatial distributions (uniform or uneven). The equal filling strategy outperforms other two strategies and it can achieve 10% more CSO reduction and 5% more flooding reduction relative to the no-tank case.

关键词: Urban drainage system     Real time control     Static strategy     Constant strategy     Equal filling strategy    

Pathogen evolution, prevention/control strategy and clinical features of COVID-19: experiences from China

《医学前沿(英文)》 doi: 10.1007/s11684-023-1043-5

摘要: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was reported at the end of 2019 as a worldwide health concern causing a pandemic of unusual viral pneumonia and many other organ damages, which was defined by the World Health Organization as coronavirus disease 2019 (COVID-19). The pandemic is considered a significant threat to global public health till now. In this review, we have summarized the lessons learnt during the emergence and spread of SARS-CoV-2, including its prototype and variants. The overall clinical features of variants of concern (VOC), heterogeneity in the clinical manifestations, radiology and pathology of COVID-19 patients are also discussed, along with advances in therapeutic agents.

关键词: coronavirus disease 2019     SARS-CoV-2     epidemiology     clinical features    

FULL TIME-SPACE GOVERNANCE STRATEGY AND TECHNOLOGY FOR CROPLAND NON-POINT POLLUTION CONTROL IN CHINA

《农业科学与工程前沿(英文)》 2023年 第10卷 第4期   页码 593-606 doi: 10.15302/J-FASE-2023522

摘要:

Ensuring food safety while reducing agricultural non-point source pollution is quite challenging, especially in developing and underdeveloped countries. Effective systematic strategies and comprehensive technologies need to be developed for agricultural non-point source pollution control at the watershed scale to improve surface water quality. In this review, a proposal is made for a full time-space governance strategy that prioritizes source management followed by endpoint water pollution control. The 4R chain technology system is specifically reviewed, including source reduction, process retention, nutrient reuse and water restoration. The 4R chain technology system with the full time-space governance strategy was applied at the scale of an administrative village and proved to be a feasible solution for reducing agricultural non-point source pollution in China. In the future, a monitoring system needs to be established to trace N and P transport. Additionally, new smart fertilizer and intelligent equipment need to be developed, and relevant governance standards and supportive policies need to be set to enhance the efficacy of agricultural non-point source pollution control.

关键词: 4R chain technology system     agricultural non-point source pollution     case study     full time-space governance strategy    

Eutrophication status and control strategy of Taihu Lake

ZHANG Limin, XIA Minfang, ZHANG Lei, WANG Chun, LU Jilai

《环境科学与工程前沿(英文)》 2008年 第2卷 第3期   页码 280-290 doi: 10.1007/s11783-008-0062-4

摘要: The water quality and eutrophication status of Taihu Lake in recent years are presented and the pollution trends are analyzed. It is shown that because of unreasonable industrial structures, pollution discharge per GDP is high within the Taihu basin, and the pollution discharge from point and non-point sources exceed the basin’s environmental carrying capacity. Especially, excessive pollutants containing nitrogen and phosphorus are being discharged. Moreover, eutrophication may also result from internal pollution sources such as the release of nutrient elements from sediment. All these factors have resulted in the water quality deterioration of Taihu Lake. To solve this environmental problem, possible control strategies are summarized, including the control of internal pollution sources and inflow-river pollution, ecological restoration and reconstruction of the degraded lakeside zone ecosystem, clean water diversion, dredging, and manual algae removal.

关键词: eutrophication     GDP     capacity     reconstruction     ecological restoration    

Regenerative braking control strategy in mild hybrid electric vehicles equipped with automatic manual

QIN Datong, YE Ming, LIU Zhenjun

《机械工程前沿(英文)》 2007年 第2卷 第3期   页码 364-369 doi: 10.1007/s11465-007-0064-0

摘要: The actual regenerative braking force of an integrated starter/generator (ISG), which is varied with desired braking deceleration and vehicle speed, is calculated based on an analysis of the required deceleration, maximum braking force of ISG, engine braking force and state of charge (SOC) of battery. Braking force distribution strategies are presented according to the actual regenerative braking force of ISG. To recover the vehicle s kinetic energy maximally, braking shift rules for a mild hybrid electric vehicle (HEV) equipped with automatic manual transmission (AMT) are brought forward and effects of transmission ratios are considered. A test-bed is built up and regenerative braking tests are carried out. The results show that power recovered by the braking shift rules is more than that recovered by the normal braking control rules.

关键词: SOC     Braking     battery     regenerative braking     starter/generator    

Analysis of load transfer stability control strategy in hydraulic synchronized continuous slippage

LIU Yan-bo, WU Jian-zhong, ZHANG Xuan

《机械工程前沿(英文)》 2006年 第1卷 第2期   页码 222-226 doi: 10.1007/s11465-006-0007-1

摘要: Hydraulic synchronized continuous slippage technique, which integrates mechanical, electrical and hydraulic control, is introduced in this paper for the practical requirements of some construction projects. The core of this technique (the stability of the load transfer) is illustrated in detail. Three speed control strategies to transfer the load excessive, lower and same speed are presented to accomplish the smoothness and stability in the process of slippage. An optimization of the speed control strategy (same speed) is deduced from the modeling analysis and its validity and maneuverability are tested by practical application, which provides evidence for similar engineering in theory and practice.

关键词: excessive     slippage technique     optimization     continuous slippage     engineering    

Air pollutant control and strategy in coal-fired power industry for promotion of China’s emission reduction

Weiliang WANG, Bo LI, Xuan YAO, Junfu LYU, Weidou NI

《能源前沿(英文)》 2019年 第13卷 第2期   页码 307-316 doi: 10.1007/s11708-019-0620-4

摘要: Coal-fired power industry has always been the major power source in China. As coal-fired power industry consumes around a half of China’s coal production, it is always thought to be a big air pollutant emission source. As more and more strict legislations in coal-fired power industry have been issued by the government, the emission performance in coal-fired power industry has been drastically reduced recently. Based on a brief review of the development of emission control in China’s coal-fired power industry, the affecting mechanism among the development of installed capacities of emission control device, pollutant emission, and emission performances in coal-fired power industry is studied. According to a systematic study on the development of emissions of classified categories, the role of coal-fired power industry as a pollutant source is reevaluated. It is found that, coal-fired power industry has contributed the most to China’s emission reduction, and the barycenter of air pollutant emission has been transformed to other high energy consumption industries, like heat, iron/steel, and cement. Then some development strategies are suggested, such as maintaining the current emission standard in coal-fired power industry; expending the coal-fired power emission standards to categories of heat generation and supply, nonmetallic mineral production and ferrous metals smelting and processing; and controlling other heavy metal by consulting the method of Hg control.

关键词: coal-fired power industry     energy intensive industries     pollutant emission control     NOx     SO2     soot    

Exploration of Strategies for Chronic Disease Prevention and Control and Relevant System Development

Long-de Wang

《工程管理前沿(英文)》 2015年 第2卷 第1期   页码 2-12 doi: 10.15302/J-FEM-2015002

摘要: Chronic non-communicable diseases have become a major threat to humanity. International studies have shown that of 57 million deaths worldwide in 2008, 36 million (63%) were caused by chronic non-communicable diseases; of these, 29 million (80%) occurred in low and middle income countries. The WHO predicts that if the current trend continues, the annual number of deaths due to chronic non-communicable diseases will increase to 55 million by 2030. Due to acceleration of industrialization and urbanization, along with population aging and rapid changes of people’s lifestyle, the morbidity and mortality from chronic diseases are rapidly increasing in China. Therefore, dealing with the prevalence of chronic non-communicable diseases has become one of the current major health issues for China to address. On the basis of summarizing the status of major chronic diseases in China, analyzing the key issues and key factors in chronic disease prevention and control, and reviewing and summarizing the experience from the previous projects, this paper proposes the following recommendations as strategies for chronic disease prevention and control and development of relevant system, which China should adopt. All relevant government departments should formulate corresponding policies; establish a coordinated and efficient work system with rational structure and clear division of tasks and responsibilities within the system. Implementation and development of “integrated medicine” in system is necessary. Work norms and requirements will then improve the performance and efficiency in chronic disease prevention and control in China.

关键词: chronic disease prevention and control     strategy and system construction    

Chord error constraint based integrated control strategy for contour error compensation

Tie ZHANG, Caicheng WU, Yanbiao ZOU

《机械工程前沿(英文)》 2020年 第15卷 第4期   页码 645-658 doi: 10.1007/s11465-020-0601-7

摘要: As the traditional cross-coupling control method cannot meet the requirements for tracking accuracy and contour control accuracy in large curvature positions, an integrated control strategy of cross-coupling contour error compensation based on chord error constraint, which consists of a cross-coupling controller and an improved position error compensator, is proposed. To reduce the contour error, a PI-type cross-coupling controller is designed, with its stability being analyzed by using the contour error transfer function. Moreover, a feed rate regulator based on the chord error constraint is proposed, which performs speed planning with the maximum feed rate allowed by the large curvature position as the constraint condition, so as to meet the requirements of large curvature positions for the chord error. Besides, an improved position error compensation method is further presented by combining the feed rate regulator with the position error compensator, which improves the tracking accuracy via the advance compensation of tracking error. The biaxial experimental results of non-uniform rational B-splines curves indicate that the proposed integrated control strategy can significantly improve the tracking and contour control accuracy in biaxial contour following tasks.

关键词: cross-coupling controller     contour error     tracking error     position error compensator     feed rate regulator    

我国细菌耐药问题的现状和防控策略

夏照帆,吕开阳,汤陈琪,李骏强

《中国工程科学》 2017年 第19卷 第2期   页码 106-111 doi: 10.15302/J-SSCAE-2017.02.018

摘要:

细菌耐药危机日趋严峻,已经成为全球范围内的重大公共安全问题,严重危害人类、动物的健康和生态环境。本文总结了我国各领域细菌耐药问题的现状,分析了加剧细菌耐药性的直接原因,揭示了细菌耐药问题对国民健康、食品安全、生态环境、经济发展等可能造成的危害,整理了我国目前开展的防控行动以及取得的主要成果,最后针对我国细菌耐药防控在耐药监测、抗生素监管、危害风险评估、人才队伍建设等方面的不足,提出了多领域合作、多部门联防联控的细菌耐药防控策略。

关键词: 细菌耐药     抗生素     可持续发展     防控策略    

A combined control strategy using tuned liquid dampers to reduce displacement demands of base-isolated

Parham SHOAEI, Houtan Tahmasebi OROMI

《结构与土木工程前沿(英文)》 2019年 第13卷 第4期   页码 890-903 doi: 10.1007/s11709-019-0524-8

摘要: This paper investigates a hybrid structural control system using tuned liquid dampers (TLDs) and lead-rubber bearing (LRB) systems for mitigating earthquake-induced vibrations. Furthermore, a new approach for taking into account the uncertainties associated with the steel shear buildings is proposed. In the proposed approach, the probabilistic distributions of the stiffness and yield properties of stories of a set of reference steel moment frame structures are derived through Monte-Carlo sampling. The approach is applied to steel shear buildings isolated with LRB systems. The base isolation systems are designed for different target base displacements by minimizing a relative performance index using Genetic Algorithm. Thereafter, the base-isolated structures are equipped with TLDs and a combination of the base and TLD properties is sought by which the maximum reduction occurs in the base displacement without compromising the performance of the system. In addition, the effects of TLD properties on the performance of the system are studied through a parametric study. Based on the analyses results, the base displacement can be reduced 23% by average, however, the maximum reduction can go beyond 30%.

关键词: tuned liquid damper     lead-rubber bearing system     probabilistic framework     steel shear building     relative performance index     Monte-Carlo sampling    

油缸实时检测系统控制策略研究

龚进,谭青,赵喻明,衡保利

《中国工程科学》 2011年 第13卷 第3期   页码 71-76

摘要:

针对现有油缸检测系统检测手段和技术落后及检测精度低等缺点,提出把测试项目模块化后,将模块有机组织在液压缸运行过程中来完成油缸检测的控制策略。运用PLC(programmable logic controller,可编程控制器)控制、CoDeSys组态软件和Visual Basic 6.0技术设计了一套油缸实时检测系统。试验结果表明,新的测试系统实现了实时检测、试验数据和曲线以及试验报告的输出和打印,提高了检测效率。

关键词: 油缸     实时检测     模块化     控制策略    

Impact of selection of DC base values and DC link control strategies on sequential AC-DC power-flow convergence

Shagufta KHAN,Suman BHOWMICK

《能源前沿(英文)》 2015年 第9卷 第4期   页码 399-412 doi: 10.1007/s11708-015-0374-6

摘要: This paper demonstrates the convergence of the integrated AC-DC power-flow algorithm as affected by the selection of different base values for the DC quantities and adoption of different control strategies for the DC link. For power-flow modeling of integrated AC-DC systems, the base values of the various DC quantities can be defined in several ways, giving rise to different sets of per-unit system equations. It is observed that different per-unit system models affect the convergence of the power-flow algorithm differently. In a similar manner, the control strategy adopted for the DC link also affects the power-flow convergence. The sequential method is used to solve the DC variables in the Newton Raphson (NR) power flow model, where AC and DC systems are solved separately and are coupled by injecting an equivalent amount of real and reactive power at the terminal AC buses. Now, for a majority of the possible control strategies, the equivalent real and reactive power injections at the concerned buses can be computed a-priori and are independent of the NR iterative loop. However, for a few of the control strategies, the equivalent reactive power injections cannot be computed a-priori and need to be computed in every NR iteration. This affects the performance of the iterative process. Two different per-unit system models and six typical control strategies are taken into consideration. This is validated by numerous case studies conducted on the IEEE 118-bus and 300-bus test systems.

关键词: AC-DC power-flow     Newton-Raphson method     high voltage direct current (HVDC) control strategy    

Multidisciplinary co-design optimization of structural and control parameters for bucket wheel reclaimer

Yongliang YUAN, Liye LV, Shuo WANG, Xueguan SONG

《机械工程前沿(英文)》 2020年 第15卷 第3期   页码 406-416 doi: 10.1007/s11465-019-0578-2

摘要: Bucket wheel reclaimer (BWR) is an extremely complex engineering machine that involves multiple disciplines, such as structure, dynamics, and electromechanics. The conventional design strategy, namely, sequential strategy, is structural design followed by control optimization. However, the global optimal solution is difficult to achieve because of the discoordination of structural and control parameters. The co-design strategy is explored to address the aforementioned problem by combining the structural and control system design based on simultaneous dynamic optimization approach. The radial basis function model is applied for the planning of the rotation speed considering the relationships of subsystems to minimize the energy consumption per volume. Co-design strategy is implemented to resolve the optimization problem, and numerical results are compared with those of sequential strategy. The dynamic response of the BWR is also analyzed with different optimization strategies to evaluate the advantages of the strategies. Results indicate that co-design strategy not only can reduce the energy consumption of the BWR but also can achieve a smaller vibration amplitude than the sequential strategy.

关键词: bucket wheel reclaimer     co-design     energy-minimum optimization     sequential strategy    

标题 作者 时间 类型 操作

Fault tolerant control strategy for modular PWM current source inverter

期刊论文

Design and evaluation of control strategies in urban drainage systems in Kunming city

Xin Dong, Senchen Huang, Siyu Zeng

期刊论文

Pathogen evolution, prevention/control strategy and clinical features of COVID-19: experiences from China

期刊论文

FULL TIME-SPACE GOVERNANCE STRATEGY AND TECHNOLOGY FOR CROPLAND NON-POINT POLLUTION CONTROL IN CHINA

期刊论文

Eutrophication status and control strategy of Taihu Lake

ZHANG Limin, XIA Minfang, ZHANG Lei, WANG Chun, LU Jilai

期刊论文

Regenerative braking control strategy in mild hybrid electric vehicles equipped with automatic manual

QIN Datong, YE Ming, LIU Zhenjun

期刊论文

Analysis of load transfer stability control strategy in hydraulic synchronized continuous slippage

LIU Yan-bo, WU Jian-zhong, ZHANG Xuan

期刊论文

Air pollutant control and strategy in coal-fired power industry for promotion of China’s emission reduction

Weiliang WANG, Bo LI, Xuan YAO, Junfu LYU, Weidou NI

期刊论文

Exploration of Strategies for Chronic Disease Prevention and Control and Relevant System Development

Long-de Wang

期刊论文

Chord error constraint based integrated control strategy for contour error compensation

Tie ZHANG, Caicheng WU, Yanbiao ZOU

期刊论文

我国细菌耐药问题的现状和防控策略

夏照帆,吕开阳,汤陈琪,李骏强

期刊论文

A combined control strategy using tuned liquid dampers to reduce displacement demands of base-isolated

Parham SHOAEI, Houtan Tahmasebi OROMI

期刊论文

油缸实时检测系统控制策略研究

龚进,谭青,赵喻明,衡保利

期刊论文

Impact of selection of DC base values and DC link control strategies on sequential AC-DC power-flow convergence

Shagufta KHAN,Suman BHOWMICK

期刊论文

Multidisciplinary co-design optimization of structural and control parameters for bucket wheel reclaimer

Yongliang YUAN, Liye LV, Shuo WANG, Xueguan SONG

期刊论文