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ON THE LAGRANGIAN TIDAL RESIDUAL CIRCULATION IN THE BOHAI SEA
Hao Wei,Liang Zhao,Shi Zuo Feng 한국해안해양공학회 1999 학술강연회 발표논문초록집 Vol.1 No.1
Tidal residual is very important to the transport in the coastal sea. In our point of view Lagrangian time averaged residual is relevent to the Eulerian one to embody the coastal circulation. Tidal system of Bohai Sea is simulated by HAMSOM and both of two kinds of tidal residual are calculated at the mean time. There are significant differences between them in some area.
Wei-Bin Ni,De-Hao Qiao,Hong-Wei Sun,Xu Zhang,Zhong-Wen Zhang,Shao-Jie Wang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.2
Precast concrete frame structure with nonrectangular columns are becoming attractive to researchers and engineers owing to advantages such as avoiding column protrusion from walls and saving space. This paper presents the experimental investigation of a full-scale precast concrete frame structure with L-shaped columns (PCFS) subjected to reverse cyclic loading. The precast connection adopted grouted anchor connection. As a comparison and benchmark, one full-scale monolithic sample (RCFS) was also tested. The results indicates that the greater steel ratio in the grouted anchor connection region leads to a high local stiffness of the elements, which contributed to delaying occurrence of the first crack at the grouting holes. The failure mode, lateral load capacity, stiffness degradation, load-carrying capacity degradation, energy-dissipating capacity, ductility and interlayer residual deformation were compared between two specimens. PCFS specimen exhibited comparatively better hysteretic behavior, energy-dissipating capacity, residual deformation-resisting capacity and ductility. For RCFS and PCFS specimens, the peak load difference was within 7%. About 15% increases in ductility were observed for PCFS specimen compared with RCFS specimen. The test results would provide reference for the application of the precast concrete structure with nonrectangular columns in the new residential buildings.
Hao Wei,박지은,Yoo Gyeong Park,ByoungRyongJeong 한국원예학회 2019 Horticulture, Environment, and Biotechnology Vol.60 No.3
Seedling production is the basis of most agricultural, especially horticultural, cultivation and is important for crop cultivation. The quality of seedlings directly aff ects the quality and yield of crops after transplanting. The scale of seedling production inthe Republic of Korea has increased gradually and signifi cantly, and the proportion of grafted seedlings of fruit vegetableshas become increasingly important. The quality of grafted vegetable seedlings is valued by farmers more than before; thus,the quality of grafted seedlings of fruit vegetables has become an important area of study. To determine the direction of thisresearch, we surveyed several representative seedling production growers in diff erent provinces of the Republic of Korea. Weinvestigated the graft healing methods used by Korean growers of fruit vegetable plug seedlings, including the light intensity,air temperature, and relative humidity in plug seedling cultivation greenhouses, graft healing tunnels, and closed-type grafthealing factories in summer and winter seasons. It was found that the graft healing methods used by diff erent growers varied. There were vast diff erences in air temperature and relative humidity between graft healing tunnels and closed-type healingfactories. In greenhouses, the temperature in winter was low and the light intensity was insuffi cient, while the temperature insummer was high and relative humidity was too low to be optimal for grafted seedlings. Due to the diff erences in coveringmaterials, the light spectrum in cultivation greenhouses and the graft healing spaces also varied among growers. In general,there were no standardized production models or environmental conditions for grafted plug seedling cultivation. Therefore,follow-up studies will be needed for the development of the grafted plug seedling industry in Republic of Korea.
Hao Luo,Mingyao Lin,Yang Cao,Wei Guo,Li Hao,Peng Wang 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.5
The ride-through control of a doubly-fed induction generator (DFIG) for the voltage sags on wind farms utilizing crowbar circuits by which the rotor side converter (RSC) is disabled has being reported in many literatures. An analysis and calculation of the transient current when the RSC is switched off are of significance for carrying out the low voltage ride through (LVRT) of a DFIG. The mathematical derivation is highlighted in this paper. The zero-state and zero-input responses of the transient current in the frequency domain through a Laplace transformation are investigated, and the transient components in the time domain are achieved. With the characteristics worked out from the linear resolving without modeling simplification, the selection of the resistance in the linear crowbar circuit and the value conversion from a linear circuit to a nonlinear one is proposed to setup the attenuation rate. In terms of grid code requirements, the theoretical analysis for the time constant of the transient components attenuation insures the controllability when the excitation of the RSC is resumed and it guarantees the reserved time for the response of the reactive power compensation. Simulations are executed in MATLAB/SIMPOWER and experiments are carried out to validate the theoretical analysis. They indicate that the calculation method is effective for selection of the resistance in a crowbar circuit for LVRT operations.
Hao Hu,Xiaogang Sun,Wei Chen,Jie Wang,Xu Li,Yapan Huang,Chengcheng Wei,Guodong Liang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.7
Carbon nanotubes (CNTs) were doped by ammonium borate as the sources of nitrogen and boron. Under the protection of Ar gas, boron-nitrogen doped CNTs were prepared through nitriding and boronization at high temperature. It is a conductive additive. Then, the obtained CNTs were mixed with activated carbon (AC), SP, sodium dodecyl sulfate (SDS), and cellulose fiber to prepare electrodes. With all the materials, a symmetric electric double-layer supercapacitor (EDLC) was assembled. Next, the materials and electrodes were also characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The factors, chemical connections, and specific surface area of the CNTs were analyzed by X-ray energy spectrum analysis (EDS), X-ray photoelectron spectroscopy (XPS), as well as a specific surface area and porosimetry analyzer (BET). In addition, the electrochemical performances of electric double-layer capacitors were tested with the help of cyclic voltammetry, constant-current charging and discharging, and so on. From the results, we can make a conclusion, that is, both B and N atoms were added into the CNTs and formed bonds successfully with carbon atoms mutually. Besides, the specific surface area is about 1.5 times than that of the CNT. When the charge/discharge current density reaches 50 mA/g, we can find that the mass specific capacitance of the capacitor can run up to 32.19 F/g. Also, we observe that the maximum power density is close to 220 W/kg (700 mA/g), and the energy density can arrive 9.31 Wh/kg (50 mA/g). Based on the impedance test, the electrodes are characterized with low impedance. After 2000 cycles, the boron-nitrogen doped double-layer capacitors maintain a capacitance retention ratio of above 95%. Its power density can still achieve 220 W/kg when the energy density keeps at 3.46 Wh/kg. In other words, the electrochemical performance functions of the electric double-layer capacitors are enhanced while the CNTs serve as the electrodes.
Active Disturbance Rejection Control for Nanopositioning Systems with Piezoelectric Actuators
Wei Wei,Ran Zhang,Jing Wang,Guang-Bo Hao 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10
Nanopositioning proposes a high demand for its control system. However, hysteresis, a common nonlinear phenomenon existing in piezoelectric actuator, decreases precision of nanopositioning. In this paper, active disturbance rejection control (ADRC) is designed to estimate and cancel the influence of hysteresis, and integral time absolute error (ITAE) optimal index is chosen to determine the parameters of ADRC. Simulations are performed on the basis of mathematic model of nanopositioning system, and numerical results show that ADRC is effective in the control of nanopositioning.
Control of thermoacoustic instability of liquid-spray flame with porous sound absorber
Hao Zhou,Hao Fang,Dongliang Wei,Zihua Liu,Zhaowen Wang,Hanxiao Meng 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8
A kind of porous sound absorber was studied to control the thermoacoustic oscillation of liquid mist flame, which combined natural fibrous materials and perforated plate. It could optimize the sound absorption characteristics of fibrous materials by adding perforated plate and air cavity. The influences of the interlayer and back cavity depth of two kinds of fibrous materials with the mass of 20, 30, 40 g were investigated experimentally in an impedance tube and applied to control the oscillating ethanol flame. The results showed that the best depth of interlayer and back cavity were 20 cm and 30 cm, respectively. The addition of two kinds of fiber sandwich structures could reduce the amplitude of the sound pressure oscillation in the combustion chamber by 89.2 % and 92.6 %, as well as 88.0 % and 91.2 % in the plenum chamber, meanwhile, restrained the flame heat release fluctuation by 73 %. It was proved that the porous sound absorber could act as a damp in the acoustic transmission path and suppress the sound source.