Power conditioning system of Flywheel Energy Storage

Zhongwei Chen,Xudong Zou,Shanxu Duan,Huarong Wei 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

In a Flywheel Energy Storage system (FESS), the power conditioning system is the key component of controlling power transfer between the Flywheel and the power system. The dynamics of the power conditioning system directly affect the effect of FESS in dynamic regulation of power system. In this paper, power conditioning system which is made up of a doubly-fed induction machine (DFIM) connected with flywheel, a back-to-back converter for AC excitation and an excitation vector control system is studied. The excitation control strategy is presented for FESS DFIM to improve transient stability and increase transfer capability of power systems. The proposed control method has good dynamics that can respond to the system power demand quickly and accurately. Moreover, the proposed control method has good robust characteristic and applicability to improve the performance of power conditioning system. Simulation and experiment results are performed to evaluate the performance of the proposed control method.

Release Control of Drug-encapsulated Liposomes

Zhongwei Jiang,Guoming Chen,Takaaki Kawazu,Minoru Morita 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8

Liposomes as a drug delivery system has been an attracting interest to many researchers. This paper concerns with the study on how to control the release rate of the inner-substances from liposomes by the ultrasonic irradiation. Two kinds of ultrasonic control methods are tested for investigation of the efficiency of the release property of the liposomes. One control method is to increase the input power by fixing its frequency at the probe resonant frequency of 28.18kHz. Another method is to adjust the input frequency around the probe resonant frequency but fixing the input power. In the experiment, instead of the drug, calcein is enclosed into the liposomes and the release effect is evaluated from the fluorescence intensity changes which is measured by a spectrofluorometer. The experiment results showed that the efficient release property can be achieved both by control of the input power and input frequency, but adjusting the input frequency around the probe resonant frequency can get higher efficient release performance than that controlled by the input power.

Investigations on Influence of Erection Process on Buckling of Large Span Structures by a Novel Numerical Method

Zhongwei Zhao,Zhi-Hua Chen,Hongbo Liu,Bingzhen Zhao 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.3

The erection process of long-span spatial structures is significantly nonlinear which is often accompanied by variations in boundary condition and material property. Many researchers have conducted investigations on construction simulation of complex structures. But few investigate influence of erection process on buckling behavior of structures in service. A method for estimating the influence was proposed. The reliability and accuracy of this method was validated. Then three kinds of structures were analyzed to estimate influence of erection process. The results indicate that some kinds of structures are sensitive to erection process. Influence of erection process on buckling capacity should be considered appropriately.

Optimizing the Construction Procedures of Large-span Structures Based on a Real-coded Genetic Algorithm

Zhongwei Zhao,Han Zhu,Zhi-Hua Chen,Yansheng Du 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.3

The erection phase is the most vulnerable period in the life of a structure. However, no mature and effective method for optimizing the construction procedures of large-span steel structures is yet available. Thus, proposing an optimization method for constructing such structures is critical. A real-coded genetic algorithm (GA) was proposed in the present work, and the selection, crossover, and mutation operators were programmed. The proposed algorithm is effective in optimizing integer combinations and sequences, such as an unloading sequence. A series of problems that occurred during the erection of conchshaped complex large steel structures was optimized using the proposed method. Optimum analysis was conducted using MATLAB and the general finite element software ANSYS. The optimal layouts of the lifting points, false work, and unloading sequence were derived. The influence of the GA parameters on its convergence efficiency was also studied. Therefore, the proposed GA method is reliable and effective for optimizing the construction procedures of large-span steel structures.

Social Identity at Work : Interpreter’s Grammatical Choices and Interpersonal Alignment

Yi Chen,Zhongwei Song 이화여자대학교 통역번역연구소 2018 T&I review Vol.8 No.-

This study explores the role Chinese government in-house interpreters have played at several high-level annual press conferences hosted by the Chinese government. By analyzing their interpreting choices for elements of MOOD, defined in the Systemic Functional Linguistic as a discourse analysis tool and using data from a self-built corpus consisting of multiple video clips of the events, this study has discovered that the interpreters realise a level of interpersonal alignment with only one party in interpreter-mediated communication, and that the choices of alignment are heavily affected by the interpreter’s evaluation of the power relationship. The findings also suggest that although greatly constrained by their institutional roles, these interpreters remain as linguistic professionals. However, their grammatical choices demonstrate a tendency of their shifting social positions between the speaker and the addressees, betraying their deliberate efforts in embracing two roles in interpreting for the press conferences - one as inseparable part of the institution with allegiance pledged to the government, and the other as individual interpreters adhering to the norms of the profession.

The Step-by-Step Model Technology Considering Nonlinear Effect Used for Construction Simulation Analysis

Zhihua Chen,Zhongwei Zhao,Han Zhu,Xiaodun Wang,Xiangyu Yan 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.2

Long-span spatial structures have advantages over other structural systems in terms of novelty and aesthetics in architectural form. However, the complexity of stress distribution causes these kinds of structures to change significantly between the construction and utilization stages. One-time loading method was used in the traditional design method to calculate and evaluate structural stress and structural deflection, either of which could cause problems in component size and residual stress during construction process. Therefore, construction simulation analysis of these structures must be performed. Element birth and death technology and step-by-step model technology (SSMT) are the main approaches in the finite element method used in construction analysis. This paper proposes a theory basis for the SSMT that was used in the constructional analysis of the Yujiapu Railway Station Building. Results obtained by the proposed method were compared with those by element birth and death technology. In addition, the preset construction deformation value was calculated to validate the correctness and efficiency of the proposed method.

Triboelectric electronic-skin based on graphene quantum dots for application in self-powered, smart, artificial fingers

Xu, Zhongwei,Wu, Chaoxing,Li, Fushan,Chen, Wei,Guo, Tailiang,Kim, Tae Whan Elsevier 2018 Nano energy Vol.49 No.-

<P><B>Abstract</B></P> <P>The development of electronic-skin (e-skin) with artificial tactile-perception is crucial for emerging artificial-intelligence systems. However, considering the relatively simple function of existing e-skins, their performances still have much room for improvement. Here, a cuttable, transparent, stretchable, and lightweight e-skin that functions on the basis of the triboelectric effect is demonstrated. Well-designed micro-gaps are introduced to make the e-skin respond sensitively to various mechanical stimulations, including pressing, stretching, folding, and twisting. Ag nanowires coated with graphene quantum dots are employed as the electrode, as well as the friction layer, to increase the sensitivity to external mechanical stimulations. Self-powered, smart, artificial fingers with tactile sensation to monitor the actions of the fingers were fabricated to demonstrate the potential application of our newly developed e-skin. The architecture and the material system of the device demonstrated in this work will promote the development of human-machine interfaces and intelligent machines.</P> <P><B>Highlights</B></P> <P> <UL> <LI> E-skins on the basis of the triboelectric effect are demonstrated. </LI> <LI> The e-skin responds sensitively to various mechanical stimulations. </LI> <LI> Graphene quantum dot-coated Ag nanowires are employed to increase the sensitivity to the mechanical stimulations. </LI> <LI> Self-powered, smart, artificial fingers based on the e-skins are demonstrated. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Ultrathin electronic synapse having high temporal/spatial uniformity and an Al2O3/graphene quantum dots/Al2O3 sandwich structure for neuromorphic computing

Xu, Zhongwei,Li, Fushan,Wu, Chaoxing,Ma, Fumin,Zheng, Yueting,Yang, Kaiyu,Chen, Wei,Hu, Hailong,Guo, Tailiang,Kim, Tae Whan Springer Science and Business Media LLC 2019 NPG Asia Materials Vol.11 No.-

A Simplified Numerical Model for Post-tensioned Steel Connections with Bolted Angles

Zhi-Hua Chen,Hongxing Li,Zhongwei Zhao,Haiqing Liu 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.4

Post-tensioned (PT) self-centering beam–column connections has been developed for its good seismic performance. Many researchers have investigated its mechanical behavior by numerical or experimental method. Prior researches have indicated that the analysis by elaborate FE models is very time consuming. To overcome this disadvantage, a simplified numerical model was established in this paper. The accuracy of results derived by this model was validated against prior investigations on interior PT connections with top-and-seat angles. Influence of initial PT force on mechanical behavior of PT connection was investigated. The Geometric and material nonlinearities, and strands can be considered in the modeling. A planar steel frame structure was established and hysteretic analysis was conducted. Results indicated that the computational cost can be greatly reduced by this model.

Syntactic Linearity as a Strategy in Simultaneous Interpreting : A Case Study on English-Chinese Interpretation

Canzhong Wu,Zhongwei Song,Yi Chen 이화여자대학교 통역번역연구소 2015 T&I review Vol.5 No.-

This study has assessed whether syntactic linearity can be used as one of SI strategies from a linguistic perspective. Using Systemic Functional Linguistics (SFL) as the linguistic framework, the study analyses the thematic choices of Obama’s speech made in his visit to China and its simultaneous interpretation by three interpreters and focuses on the analytic unit of clause being grammatically correlated to the “unit of meaning” in the TL. The findings show that most of the Themes in English text are preserved in Chinese. Furthermore, the textual and topical elements of Theme in English are more influential than the interpersonal Theme for the interpreters to decide whether a Theme should be retained or changed in facilitating syntactic linearity in SI. The assessment result seems to support that syntactic linearity could be used as a strategy for SI training together with other coping strategies.