Infuence of Dynamic Characteristics of Induction Motor on Voltage Sag Caused by Short Circuit Fault

Jiming Chen,Hai Zuo,Qianyu Yu,Lizhi Qi,Mingxiao Zhu 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.4

Voltage sag is a signifcant problem that afects the quality of power, and some researches have been performed on this theme. The characteristic of load is an important factor afecting the voltage sag, which is rarely studied. This paper investigates the infuence of dynamic characteristics of induction motor on voltage sag caused by short circuit fault. The analytic expression of induction electromotive force is derived by space vector method. The mechanism of amplitude and waveform changes caused by dynamic load characteristics of induction motor are analyzed. The results indicate that the voltage at the load terminal of the induction motor is higher than that at the static load during the sag. Besides, the voltage sag waveform is not in rectangular shape. The static load terminal voltage returns to normal value quickly, while the voltage at the load terminal of the induction motor needs about 200 ms after the fault is removed. Induction motors can reduce the magnitude of voltage sags caused by short circuit faults, but will extend the duration. At the same time, the bigger the induction motor capacity is, the longer the voltage recovery time after sag is.

Exploratory study on wind-adaptable design for super-tall buildings

Jiming Xie,Xiao-yue Yang 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.6

Wind-adaptable design (WAD) provides a new method for super-tall buildings to lessen design conflicts between architectural prerequisites and aerodynamic requirements, and to increase the efficiency of structural system. Compared to conventional wind-resistant design approach, the proposed new method is to design a building in two consecutive stages: a stage in normal winds and a stage during extreme winds. In majority of time, the required structural capacity is primarily for normal wind effects. During extreme wind storms, the building’s capacity to wind loads is reinforced by on-demand operable flow control measures/devices to effectively reduce the loads. A general procedure for using WAD is provided, followed by an exploratory case study to demonstrate the application of WAD.

Enhanced luminescence of Tb3+ by efficient energy transfer from Ce3+ in Sr2B5O9Cl host

Jiming Zheng,Chongfeng Guo,Xu Ding,Zhaoyu Ren,Jintao Bai 한국물리학회 2012 Current Applied Physics Vol.12 No.3

Ce3+ and Tb3+ co-doped Sr2B5O9Cl phosphors with intense green emission were prepared by the conventional high-temperature solid-state reaction technique. A broad band centered at about 315 nm was found in phosphor Sr2B5O9Cl: Ce3+, Tb3+ excitation spectrum, which was attributed to the 4f-5d transition of Ce3+. The typical sharp line emissions ranging from 450 to 650 nm were originated from the 5D4/7FJ (J ¼ 6, 5, 4, 3) transitions of Tb3+ ions. The photoluminescence (PL) intensity of green emission from Tb3+ was enhanced remarkably by co-doping Ce3+ in the Tb3+ solely doped Sr2B5O9Cl phosphor because of the dipoleedipole mechanism resonant energy transfer from Ce3+ to Tb3+ ions. The energy transfer process was investigated in detail. In light of the energy transfer principles, the optimal composition of phosphor with the maximum green light output was established to be Sr1.64Ce0.08Tb0.1Li0.18B5O9Cl by the appropriate adjustment of dopant concentrations. The PL intensity of Tb3+ in the phosphor was enhanced about 40 times than that of the Tb3+ single doped phosphor under the excitation of their optimal excitation wavelengths.

HFFB technique and its validation studies

Jiming Xie,Jason Garber 한국풍공학회 2014 한국풍공학회지 Vol.18 No.4

The high-frequency force-balance (HFFB) technique and its subsequent improvements are reviewed in this paper, including a discussion about nonlinear mode shape corrections, multi-force balance measurements, and using HFFB model to identify aeroelastic parameters. To apply the HFFB technique in engineering practice, various validation studies have been conducted. This paper presents the results from an analytical validation study for a simple building with nonlinear mode shapes, three experimental validation studies for more complicated buildings, and a field measurement comparison for a super-tall building in Hong Kong. The results of these validations confirm that the improved HFFB technique is generally adequate for engineering applications. Some technical limitations of HFFB are also discussed in this paper, especially for higher-order mode response that could be considerable for super tall buildings.

Wind-induced response of a twin-tower structure

Xie, Jiming,Irwin, Peter A. Techno-Press 2001 Wind and Structures, An International Journal (WAS Vol.4 No.6

With a newly developed multi-force-balance system(MFB), a twin-tower structure was studied for its wind-induced responses. The MFB system allowed the twin towers, which were linked structurally, to be treated as a single structural system with its corresponding modes of vibration involving coupled motions of the two towers. The towers were also studied using a more conventional force balance approach in which each tower was treated as an isolated structure, i.e., as though no structural link existed. Comparison of the results reveals how the wind loads between the towers are redistributed through the structural links and the modal couplings. The results suggest that although the structural links usually have beneficial impacts on wind-induced response, they may also play a negative role if the frequency ratios of pair modes are near 1.0.

COMMUNICATION CONSTRUCTION & ITS FUND RAISING OF SHANGHAI INTERNATIONAL METROPOLIS

Huang Jiming 대한교통학회 1998 대한교통학회 기타자료 Vol.1998 No.-

The article describes the development concept of global, regional and urban communication from the point of strategic target to build Shanghai into an international metropolis, as well its multi-way to raise funding.

Synthesis and Characteristics of Consolidated Nanocrystalline Two-Phase Ag_(50)Ni_(50) Alloy by Hot Pressing

Zhao, Jiming 한국부식방식학회 2002 Corrosion Science and Technology Vol.31 No.4

Silver and nickel are mutually only very slightly soluble and have a positive heat of mixing. Powder of Ag_50Ni_50 was prepared by mechanical alloying (MA) for 200 hr and subsquently hot pressing (HP) at 620℃ under 60 MPa. XRD results indicated that ball milling produced a mixture oftwo-phase mixture of supersaturated, nanocrystalline Ag-rich (αphase) and Ni-rich (βphase)solid solutions with grain sizes of 5 and 4 nm, respectively. Their grain sizes increased to about 40 and 26 nm after hot pressing. The HP Ag_50Ni_50 had a density Very close to the theoretical value. The HP alloy consisted of an interconnected network of the α phase and islands of two-nanophase mixture rich in β phase. Accordingly, the stability of the microstructure of the alloy and the effects of mechanical alloying on the supersaturation of the two phases and on the formation of the Ag-rich network were also discussed.

HFFB technique and its validation studies

Xie, Jiming,Garber, Jason Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.18 No.4

The high-frequency force-balance (HFFB) technique and its subsequent improvements are reviewed in this paper, including a discussion about nonlinear mode shape corrections, multi-force balance measurements, and using HFFB model to identify aeroelastic parameters. To apply the HFFB technique in engineering practice, various validation studies have been conducted. This paper presents the results from an analytical validation study for a simple building with nonlinear mode shapes, three experimental validation studies for more complicated buildings, and a field measurement comparison for a super-tall building in Hong Kong. The results of these validations confirm that the improved HFFB technique is generally adequate for engineering applications. Some technical limitations of HFFB are also discussed in this paper, especially for higher-order mode response that could be considerable for super tall buildings.

黃海魚類資源與增養殖問題

楊紀明(JIMING YANG) 인하대학교 해양과학기술연구소 1990 黃海硏究 Vol.3 No.5

COMMUNICATION CONSTRUCTION & ITS FUND RAISING OF SHANGHAI INTERNATIONAL METROPOLIS

Huang Jiming 대한교통학회 1998 대한교통학회 기타자료 Vol.1996 No.-