Elasto-plastic time history analysis of an asymmetrical twin-tower rigid-connected structure

Xiaohan Wu,Yanfei Sun,Mingzhuo Rui,Min Yan,Lishu Li,Dongze Liu 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.12 No.2

The structure analyzed in this paper has particular building style and special structural system. It is a rigid-connected twin-tower skyscraper with asymmetrical distribution of stiffness and masses in two towers. Because of the different stiffness between the north and the south towers, the torsion seismic vibration is significant. In this paper, in order to study the seismic response of the structure under both frequent low-intensity earthquakes as well as rare earthquakes at the levels of intensity 7, the analysis model is built and analyzed with NosaCAD. NosaCAD is an nonlinear structure analysis software based on second-development of AutoCAD with ObjectARX. It has convenient modeling function, high computational efficiency and diversity post-processing functions. The deformations, forces and damages of the structure are investigated based on the analysis. According to the analysis, there is no damage on the structure under frequent earthquakes, and the structure has sufficient capacity and ductility to resist rare earthquakes. Therefore the structure can reach the goal of no damage under frequent earthquakes and no collapse under rare earthquakes. The deformation of the structure is below the limit in Chinese code. The time sequence and distribution of damages on tubes are reasonable, which can dissipate some dynamic energy. At last, according to forces, load-carrying capacity and damage of elements, there are some suggestions on increasing the reinforcement in the core tube at base and in stiffened stories.

Elasto-plastic time history analysis of a 117-story high structure

Xiaohan Wu,Yimiao Li,Yunlei Zhang 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.1

In Chinese Design Codes, for super high-rise buildings with complex structural distribution, which are regarded as code-exceeding buildings, elasto-plastic time history analysis is needed to validate the requirement of “no collapse under rare earthquake”. In this paper, a 117-story super high-rise building is discussed. It has a height of 597 m and a height-width ratio of 9.5, which have both exceeded the limitations stipulated by the Chinese Design Codes. Mega columns adopted in this structure have cross section area of about 45 m2 at the bottom, which is infrequent in practical projects. NosaCAD and Perform-3D, both widely used in nonlinear analyses, were chosen in this study, with which two model were established and analyzed, respectively. Elasto-plastic time history analysis was conducted to look into its seismic behavior, emphasizing on the stress state and deformation abilities under intensive seismic excitation.From the comparisons on the results under rare earthquake obtained from NosaCAD and Perform-3D, the overall responses such as roof displacement, inter story drift, base shear and damage pattern of the whole structure from each software show agreement to an extent. Besides, the deformation of the structure is below the limitation of the Chinese Codes, the time sequence and distribution of damages on core tubes are reasonable, and can dissipate certain inputted energy, which indicates that the structure can meet the requirement of “no collapse under rare earthquake”.

Illumination promoting biomass production in wastewater treatment for Rubrivivax gelatinosus

Pan Wu,Xiaohan Xu 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.6

In order to improve the reuse degree of Rubrivivax gelatinosus (R. gelatinosus) resource in soybean producing wastewater (SPW) treatment, the impacts of diverse illumination strength on R. gelatinosus biomass and organic contaminant abatement were discussed. It was reported that with the best illumination strength (6,000 lux), the production (3,800 mg/L) of biomass was increased by sixty percent of dark group. COD removal and protein removal rate got 85 and 80%. Influence of diverse illumination strength on R. gelatinosus growth were divided into three aspects, including illumination limitation (0−5,000 lux), illumination saturation (5,000−7,000 lux), illumination inhibition (8,000 lux or higher). Meanwhile, at 6,000 lux, bacteriochlorophyll and carotenoids contents, ATP production were increased by 200, 200, 43.9% severally. Appropriate illumination improved ATP production by increasing the generation of bacteriochlorophyll and carotenoids in photosynthesis. Augment of energy production provoked the biomass production and wastewater treatment. Nevertheless, low or high illumination strength was un-advantage for R. gelatinosus growth due to the illumination deficiency or restrian. Moreover, 6,000 lux shortened the treatment time from 96 h to 48 h.

The development of high fidelity Steam Generator three dimensional thermal hydraulic coupling code: STAF-CT

Zhao, Xiaohan,Wang, Mingjun,Wu, Ge,Zhang, Jing,Tian, Wenxi,Qiu, Suizheng,Su, G.H. Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.3

The thermal hydraulic performances of Steam Generator (SG) under both steady and transient operation conditions are of great importance for the safety and economy in nuclear power plants. In this paper, based on our self-developed SG thermal hydraulic analysis code STAF (Steam-generator Thermalhydraulic Analysis code based on Fluent), an improved new version STAF-CT (fully Coupling and Transient) is developed and introduced. Compared with original STAF, the new version code STAF-CT has two main functional improvements including "Transient" and "Fully Three Dimensional Coupling" features. In STAF-CT, a three dimensional energy transferring module is established which can achieve energy exchange computing function at the corresponding position between two sides of SG. The STAF-CT is validated against the international benchmark experiment data and the results show great agreement. Then the U-shaped SG in AP1000 nuclear power plant is modeled and simulated using STAF-CT. The results show that three dimensional flow fields in the primary side make significant effect on the energy source distribution between two sides. The development of code STAF-CT in this paper can provide an effective method for further SG high fidelity research in the nuclear reactor system.

Seismic behavior of a new type of seismic energy dissipation shear wall system

Lu, Xilin,Wu, Xiaohan,Meng, Liang Techno-Press 1997 Structural Engineering and Mechanics, An Int'l Jou Vol.5 No.2

A new seismic energy dissipation shear wall structure is proposed in this paper. The new shear wall is one with purposely built-in vertical slits within the wall panel, and various seismic energy dissipation devices are installed in the vertical slits so that the dynamic characteristics of the structure (for instance, lateral stiffness, ductility and fundamental period) can be controlled. In order to verify this concept, shaking table tests of two 10-story shear wall models were carried out, and the seismic behavior of the two models are studied by analyzing the test data and computing the nonlinear seismic response of the models.

Thermal Oxidation of WSe₂ Nanosheets Adhered on SiO₂/Si Substrates

Liu, Yingnan,Tan, Cheng,Chou, Harry,Nayak, Avinash,Wu, Di,Ghosh, Rudresh,Chang, Hsiao-Yu,Hao, Yufeng,Wang, Xiaohan,Kim, Joon-Seok,Piner, Richard,Ruoff, Rodney S.,Akinwande, Deji,Lai, Keji American Chemical Society 2015 NANO LETTERS Vol.15 No.8

<P>Because of the drastically different intralayer versus interlayer bonding strengths, the mechanical, thermal, and electrical properties of two-dimensional (2D) materials are highly anisotropic between the in-plane and out-of-plane directions. The structural anisotropy may also play a role in chemical reactions, such as oxidation, reduction, and etching. Here, the composition, structure, and electrical properties of mechanically exfoliated WSe<SUB>2</SUB> nanosheets on SiO<SUB>2</SUB>/Si substrates were studied as a function of the extent of thermal oxidation. A major component of the oxidation, as indicated from optical and Raman data, starts from the nanosheet edges and propagates laterally toward the center. Partial oxidation also occurs in certain areas at the surface of the flakes, which are shown to be highly conductive by microwave impedance microscopy. Using secondary ion mass spectroscopy, we also observed extensive oxidation at the WSe<SUB>2</SUB>–SiO<SUB>2</SUB> interface. The combination of multiple microcopy methods can thus provide vital information on the spatial evolution of chemical reactions on 2D materials and the nanoscale electrical properties of the reaction products.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2015/nalefd.2015.15.issue-8/acs.nanolett.5b02069/production/images/medium/nl-2015-02069p_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl5b02069'>ACS Electronic Supporting Info</A></P>

Negative sequence control for DC voltage balancing in three‑phase cascaded H‑bridge rectifiers considering DC‑port failures

Xinyu Zhu,Xiao Liang,Kaiyue Gong,Xu Peng,Jun Cai,Xiaohan Liu,Chao Zhou,Siqi An,Chao Wu,Pengcheng Han 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.12

As a vital component of power electronic transformers (PET), the reliability of a cascaded H-bridge rectifier (CHBR) is essential. Therefore, in this paper, a DC-port voltage balance strategy considering DC-port failure is researched to ensure the stable operation of a CHBR. However, if the DC-port voltage balance strategy is adopted to realize the single-phase balance of a CHBR, the three-phase currents become unbalanced. This paper uses a negative sequence control (NSC) strategy that is conducive to balancing DC-port voltage to achieve three-phase current balance. For the DC-port voltage balance, the matrix generation modulation (MGM) algorithm is proposed. In addition, the DC-port voltage balance boundary is analyzed to determine the range of the DC-port voltage balance in the CHBR. A 3-module cascading topology is adopted to demonstrate the MGM algorithm and the NSC strategy. Through experiments, results show the correctness and feasibility of the proposed strategy.

Internal filament modulation in low-dielectric gap design for built-in selector-less resistive switching memory application

Chen, Ying-Chen,Lin, Chih-Yang,Huang, Hui-Chun,Kim, Sungjun,Fowler, Burt,Chang, Yao-Feng,Wu, Xiaohan,Xu, Gaobo,Chang, Ting-Chang,Lee, Jack C IOP 2018 Journal of Physics. D, Applied Physics Vol.51 No.5

<P>Sneak path current is a severe hindrance for the application of high-density resistive random-access memory (RRAM) array designs. In this work, we demonstrate nonlinear (NL) resistive switching characteristics of a HfO<SUB> <I>x</I> </SUB>/SiO<SUB> <I>x</I> </SUB>-based stacking structure as a realization for selector-less RRAM devices. The NL characteristic was obtained and designed by optimizing the internal filament location with a low effective dielectric constant in the HfO<SUB> <I>x</I> </SUB>/SiO<SUB> <I>x</I> </SUB> structure. The stacking HfO<SUB> <I>x</I> </SUB>/SiO<SUB> <I>x</I> </SUB>-based RRAM device as the one-resistor-only memory cell is applicable without needing an additional selector device to solve the sneak path issue with a switching voltage of ~1 V, which is desirable for low-power operating in built-in nonlinearity crossbar array configurations.</P>