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Improved Model Predictive Direct Power Control of Grid Side Converter in Weak Grid Using Kalman Filter and DSOGI

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Chinese Journal of Electrical Engineering 2019年第4期5卷 22-32页

作者： Liang chen heng Nian Yunyang Xu College of Electrical Engineering Zhejiang UniversityHangzhou 310027China

When grid side converter(GSC)is connected to weak grid,the small signal instability can happen due to terminal characteristics of the GSC that are incompatible with the grid *** issue is not of wide concern in previous studies of direct power control(DPC)of *** small signal analysis,it is shown that the impedance characteristic of the conventional direct power control GSC is not compatible with the inductive grid impedance in weak grid due to its constant power load *** solve the problem,instead of feeding the DPC controller with direct measured voltage and current,a Kalman filter(KF)is used to obtain filtered output current and a double second-order generalized integrator(DSOGI)is used to obtain filtered voltage at the point of common coupling(PCC).These strategies change the impedance characteristic of the GSC dramatically and make it suitable to operate in weak grid where SCR is 2,while the rapid power response is *** proposed strategy is verified through simulation and controller hardware in loop(CHIL)tests.

关键词： Direct power control weak grid grid side converter stability

Double detonation drivers for a shock tube/tunnel

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Science China(Physics,Mechanics & Astronomy) 2004年第4期47卷 502-512页

作者： chen Hong FENG heng YU Hongru High Temperature Gas Dynamics Laboratory Institute of Mechanics Chinese Academy of SciencesBeijing 100080 China High Temperature Gas Dynamics Laboratory Institute of Mechanics Chinese Academy of SciencesBeijing 100080 China High Temperature Gas Dynamics Laboratory Institute of Mechanics Chinese Academy of SciencesBeijing 100080 China

ARecent progress on detonation drivers is reviewed. Performances of the forward detonation driver and backward detonation driver have been observed. To eliminate occurrence of a Taylor wave following the detonation wave in the primary driver and to improve the performance of the detonation driver, an additional backward detonation driver was proposed to attach to the end of the forward detonation driver. When the ratio of the initial pressures between the additional and the primary drivers becomes larger than or equal to a critical value, the Taylor wave will disappear, and thus a homogeneous driving gas with high pressure and high temperature can be generated. Furthermore, an over-driving detonation wave will be also obtained, which can increase the driving capability.

关键词： gaseous detonation, shock tube, shock tunnel.

Two-Dimensional Riemann Problems:Transonic Shock Waves and Free Boundary Problems

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Communications on Applied Mathematics and Computation 2023年第3期5卷 1015-1052页

作者： gui-Qiang G.chen Oxford Centre for Nonlinear PDE Mathematical InstituteUniversity of OxfordOxford OX26GGUK

We are concerned with global solutions of multidimensional(M-D)Riemann problems for nonlinear hyperbolic systems of conservation laws,focusing on their global configurations and *** present some recent developments in the rigorous analysis of two-dimensional(2-D)Riemann problems involving transonic shock waves through several prototypes of hyperbolic systems of conservation laws and discuss some further M-D Riemann problems and related problems for nonlinear partial differential *** particular,we present four different 2-D Riemann problems through these prototypes of hyperbolic systems and show how these Riemann problems can be reformulated/solved as free boundary problems with transonic shock waves as free boundaries for the corresponding nonlinear conservation laws of mixed elliptic-hyperbolic type and related nonlinear partial differential equations.

关键词： Riemann problems Two-dimensional(2-D) Transonic shocks Solution structure Free boundary problems Mixed elliptic-hyperbolic type Global configurations Large-time asymptotics Global attractors Multidimensional(M-D) Shock capturing methods

Design of a fully differential CMOS LNA for 3.1–10.6 GHz UWB communication systems

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The Journal of China Universities of Posts and Telecommunications 2008年第4期15卷 107-111页

作者： ZHANG Hong chen gui-can Institute of Microelectronics Xi'an Jiaotong University Xi'an 710049 China

A fully differential complementary metal oxide semiconductor （CMOS） low noise amplifier （LNA） for 3.1-10.6 GHz ultra-wideband （UWB） communication systems is presented. The LNA adopts capacitive cross-coupling common-gate （CG） topology to achieve wideband input matching and low noise figure （NF）. Inductive series-peaking is used for the LNA to obtain broadband flat gain in the whole 3.1-10.6 GHz band. Designed in 0.18 um CMOS technology, the LNA achieves an NF of 3.1-4.7 dB, an Sll of less than -10 dB, an S21 of 10.3 dB with ±0.4 dB fluctuation, and an input 3rd interception point （IIP3） of -5.1 dBm, while the current consumption is only 4.8 mA from a 1.8 V power supply. The chip area of the LNA is 1×0.94 mm^2.

关键词： LNA common gate capacitive cross coupling series peaking UWB

Geochemistry of sandstones from the Neoproterozoic Jinshanzhai Formation in northern Anhui Province, China: Provenance, weathering and tectonic setting

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Chinese Journal Of Geochemistry 2013年第1期32卷 95-103页

作者： SUN Linhua gui Herong chen Song School of Earth Science and Engineering Suzhou University

Sandstones from the Neoproterozoic Jinshanzhai Formation in northern Anhui Province, China, were analyzed for major oxides and trace elements to infer their provenance, the intensity of paleo-weathering of their source rocks and the depositional tectonic setting. Diagrams of (SiO2/20)-(Na2O+K2O)-(MgO+TiO2+FeO*), TiO2-Ni, Th-Hf-Co, Hf-La/Th and some ratios of elements indicate that felsic rocks constitute the source rocks in the provenance. The values of Chemical Index of Alteration (CIA) are low, which are considered to be affected by K-metasomatism. Whereas the high CIW (Chemical Index of Weathering) values indicate intensive weathering of the source material. Plots of sandstones on bivariate and triangle discriminant diagrams, as well as ICV (Index of Compositional Variation) values revealed that they were deposited on a passive continental margin or in an intra-plate basin. Our recent study, in combination with previous studies and the research progress of the Rodinia super continent, demonstrated that the convergence and extension of the Rodinia super continent were preserved by twice extension as expressed by petrological variation of the southeastern margin of the North China Craton (NCC) during the Neoproterozoic.

关键词：沉积构造背景中国北方新元古代地球化学特征安徽省 Rodinia超大陆砂岩耐候性

Geochemical characteristics of REE in the Late Neo-proterozoic limestone from northern Anhui Province, China

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Chinese Journal Of Geochemistry 2014年第2期33卷 187-193页

作者： chen Song gui Herong SUN Linhua School of Earth Sciences and Engineering Suzhou University School of Resource and Earth Science CUMT

Ten representative limestone samples [six from Wangshan Formation(WL) and the other four from Gouhou Formation(GL)] were collected from outcrops of the northern Anhui Province, and REE concentrations in limestone were measured by ICP-MS. The depositional environment and source of the REE were analyzed, and the results implys that the total REE of samples are low compared with the recent marine sediments, which range from 9.61 to 54.18 mg/kg and an average of 22.93 mg/kg. The PAAS-normalized REE+Y patterns of limestone are characterized by(1) light REE depletion in WL and enrichment in GL with the values of(Nd/Yb)SN ranging form 0.65 to 0.91 and 1.12 to 1.46, respectively;(2) light negative Ce anomaly(0.85–1.02) and positive La anomaly(0.92–1.27); and(3) both Eu(0.91–1.23) and Y(1.42–2.38) expressing light positive anomaly. The character indicated that the depositional environment was oxygenated, with infection by the hydrothermal activity and contamination of detritus.

关键词：稀土元素灰岩样品地球化学特征安徽省晚新元古代中国 ICP-MS Ce异常

Controllable hydrothermal synthesis of star-shaped Sr3Fe2（OH）12 assemblies and their thermal decomposition and magnetic properties

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Particuology 2016年第1期14卷 210-215页

作者： heng Zhang Tingting Wang Xiuping chen Wancheng Zhu Department of Chemical Engineering Qufu Normal University Qufu 273165 China

Pure phase star-shaped hydrogarnet Sr3Fe2（OH）12 assemblies were synthesized by a mild hydrothermal method （210℃, 12 h）, and the effects of the preparation conditions on the phase composition of the product were investigated. It was found that the impurity phases could be decreased or eliminated by increasing the molar ratio of Sr2＋ to Fe3＋, and that high temperatures favored the formation of Sr3 Fe2（OH）12 and reduced the concentration of CO32- -containing byproducts. The thermal decomposition of the star-shaped Sr3Fe2（OH）12 assemblies was examined, and the results showed that the dehydration process at higher temperatures is accompanied by the formation of SrFeO3-δ. Above 655 ℃, a solid state reaction between the SrFeO3-δ and Sr（OH）2 or SrCO3 results in the formation of Sr4Fe3O10-δ.The mag- netic properties of the as-synthesized Sr3Fe2（OH）12 and of samples calcined at different temperatures were assessed. A sample calcined at 575 ℃ exhibited greatly enhanced ferromagnetic properties, with a remanent magnetization of 1.28 emu/g and a coercivity of 4522.1 Oe at room temperature.

关键词： Hydrogarnet Hydrothermal Star-shaped Thermal decomposition Magnetic property

Improved three-vector based dead-beat model predictive direct power control strategy for grid-connected inverters

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Frontiers of Information Technology & Electronic Engineering 2018年第11期19卷 1420-1431页

作者： chen-wen Cheng heng NIAN Long-qi LI College of Electrical Engineering Zhejiang University

Since only one inverter voltage vector is applied during each duty cycle, traditional model predictive direct power control(MPDPC) for grid-connected inverters(GCIs) results in serious harmonics in current and power. Moreover, a high sampling frequency is needed to ensure satisfactory steady-state performance, which is contradictory to its long execution time due to the iterative prediction calculations. To solve these problems, a novel dead-beat MPDPC strategy is proposed, using two active inverter voltage vectors and one zero inverter voltage vector during each duty cycle. Adoption of three inverter vectors ensures a constant switching frequency. Thus, smooth steady-state performance of both current and power can be obtained. Unlike the traditional three-vector based MPDPC strategy, the proposed three vectors are selected based on the power errors rather than the sector where the grid voltage vector is located, which ensures that the duration times of the selected vectors are positive all the time. Iterative calculations of the cost function in traditional predictive control are also removed, which makes the proposed strategy easy to implement on digital signal processors(DSPs) for industrial applications. Results of experiments based on a 1 kW inverter setup validate the feasibility of the proposed three-vector based dead-beat MPDPC strategy.

关键词： Grid-connected inverter Model predictive control Direct power control Three vectors Constant switching frequency Power errors

IncPregeh an incremental graph parallel computation model

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Frontiers of Computer Science 2018年第6期12卷 1076-1089页

作者： Qiang LIU Xiaoshe DONG heng chen Yinfeng WANG School of Electronics and Information Engineering Xi'an Jiaotong UniversityXi'an 710049China Shenzhen Institute of Information Technology Shenzhen 518172China

Large-scale graph computation is often required in a variety of emerging applications such as social network computation and Web services. Such graphs are typically large and frequently updated with minor changes. However, re-computing an entire graph when a few vertices or edges are updated is often prohibitively expensive. To reduce the cost of such updates, this study proposes an incremental graph computation model called IncPregel, which leverages the non-after-effect property of the first-order Markov chain and provides incremental programming abstractions to avoid redundant computation and message communication. This is accomplished by employing an efficient and fine-grained reuse mechanism. We implemented this model on Hama, a popular open source framework based on Pregel, to construct an incremental graph processing system called IncHama. IncHama automatically detects changes in input in order to recognize “changed vertices” and to exchange reusable data by means of shuffling. The evaluation results on large-scale graphs show that, compared with Hama, IncHama is 1.1–2.7 times faster and can reduce communication messages by more than 50% when the incremental edges increase in number from 0.1 to 100k.

关键词： graph computation Pregel cloud computing