Flow between eccentric cylinders: a shear-extensional controllable flow

Guoqiang Tian,Mengmeng Wang,Xiaolin Wang,Gang Jin 한국유변학회 2016 Korea-Australia rheology journal Vol.28 No.2

In this work the non-Newtonian fluid between eccentric cylinders is simulated with finite element method. The flow in the annular gap between the eccentric rotating cylinders was found to be a shear-extensional controllable flow. The influence of rotating speed, eccentricity as well as the radius ratio on the extensional flow in the vicinity of the minimum gap between the inner and outer cylinder was quantitatively investigated. It was found that both the strengths of shear flow and extensional flow could be adjusted by changing the rotating speed. In respect to extensional flow, it was also observed that the eccentricity and radius ratio exert significant influences on the ratio of extensional flow. And it should be noted that the ratio of extensional flow in the mix flow could be increased when increasing the eccentricity and the ratio of shear flow in the mix flow could be increased when increasing the radius ratio.

Drought stress-induced changes of microRNAs in diploid and autotetraploid Paulownia tomentosa

Guoqiang Fan,Xibing Cao,Lin Cao,Minjie Deng,Zhenli Zhao,Suyan Niu,Zhe Wang,Yuanlong Wang 한국유전학회 2017 Genes & Genomics Vol.39 No.1

Drought stress adversely affects plant productivity. Growth and timber production of Paulownia trees are limited under drought stress. Changes in gene expression patterns and miRNA in different ploidy of Paulownia tomentosa have been investigated. However, the responses of P. tomentosa to drought stress at the microRNA (miRNA) level have not been reported so far. To identify miRNA candidates and their target genes involved in the drought stress response in diploid and tetraploid P. tomentosa, four small RNA and four degradome libraries from diploid and autotetraploid P. tomentosa under normal and drought stress conditions were constructed and sequenced. A total of 41 conserved and 90 novel miRNAs were identified. Among these miRNAs, 67 (26 conserved and 41 novel) and 53 (six conserved and 47 novel) were significantly differentially expressed in response to drought stress in diploid and autotetraploid P. tomentosa, respectively. Degradome analysis identified 356 candidate miRNA target genes that encoded proteins with functions that included plant defense, transcriptional regulation, and hormone metabolism. In particular, miR4 and miR156 were identified only in autotetraploid P. tomentosa under drought stress. These results will help us build a foundation for future studies of the biological functions of miRNAmediated gene regulation in P. tomentosa.

A Second-order Sliding Mode Observer Optimized by Neural Network for Speed and Position Estimation of PMSMs

Wang Guoqiang,Zhang Huilin 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.1

To improve the estimation accuracy of speed and position of surface-mounted permanent magnet synchronous motors (PMSMs), a second-order sliding mode observer (SMO) optimized by a back-propagation (BP) neural network with an improved phase-locked loop (PLL) is proposed to estimate rotor speed and position in this paper. BP neural network algorithm is used to optimize the gain of the second-order SMO, which achieves online adjustment of the gain and improves the estimation accuracy of rotor speed and position. Meanwhile, the improved PLL is used to improve the stability of the whole control system. The eff ectiveness and feasibility of the proposed method are verifi ed by experiments. The experimental results show that, compared with the adaptive fuzzy super-twisting algorithm based SMO (STA-SMO), this method eff ectively suppresses chattering, has higher accuracy of speed and position estimation and stronger robustness, and has strong practical application value in motor control.

Residual Strength of L-shaped Steel Reinforced Concrete Columns after Exposure to High Temperatures

Yuzhuo Wang,Xu Wang,Guoqiang Li,Jian Jiang,Tiangui Xu 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.4

The mechanical behavior of L-shaped steel reinforced concrete (SRC) columns after exposure to high temperatures is investigated by conducting experiments on eight column specimens. The specimens are first heated to a target temperature and are loaded to failure after cooling down to room temperature. The effect of heating duration, loading eccentricities, and loading angles on the temperature distribution, failure mode and residual bearing capacity of the columns is studied. The test results show that L-shaped SRC columns under axial and eccentric loading have a post-high temperature shear and bending failure mode, respectively. The residual bearing capacity of the specimens decreases significantly (up to 1/3) compared to that at room temperature. The residual bearing capacity of L-shaped SRC columns is governed by loading eccentricities, and an eccentricity of 80 mm (0.36) leads to a reduction in residual capacity by 47% of its ambient value. The loading angle has an obvious effect on the damage range of L-shaped SRC columns. A formula for calculating the residual bearing capacity of L-shaped SRC columns under biaxially eccentric compression is proposed and validated against test results.

Effects of metakaolin and PVA fiber on the compressive strength of shotcrete under different curing conditions

Yang Guoqiang,Guo Gang,Wang Lihui,Wang Changchang,Sun Tao 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.3

In this paper, wet shotcrete spraying experiments were carried out under different temperature and humidity conditions withdifferent dosage of metakaolin (MK) and different length of polyvinyl alcohol fiber (PVA fiber). And the influence of differentcontent of metakaolin and different length of PVA fiber on the compressive strength of tidal shotcrete under different curingconditions was explored. The results show that the compressive strength of shotcrete increases first and then decreases withthe increase of MK content and PVA fiber length under the curing condition of normal temperature and constant humidity. However, under the curing condition of high temperature and humidity, the compressive strength of shotcrete tended toincrease with the increase of MK content. Under the condition of high temperature and high humidity curing, the compressivestrength of shotcrete is lower than that of shotcrete under normal temperature and constant humidity curing. This study canprovide theoretical support for the application of sprayed concrete in different environments.

Seroprevalence of Toxoplasma gondii Infection among HIV/AIDS Patients in Eastern China

Guoqiang Shen,Xiaoming Wang,Hui Sun,Yaying Gao 대한기생충학열대의학회 2016 The Korean Journal of Parasitology Vol.54 No.1

Toxoplasmosis, a neglected tropical disease caused by the protozoan parasite Toxoplasma gondii, occurs throughout the world. Human T. gondii infection is asymptomatic in 80% of the population; however, the infection is life-threatening and causes substantial neurologic damage in immunocompromised patients such as HIV-infected persons. The major purpose of this study was to investigate the seroprevalence of T. gondii infection in subjects infected with HIV/AIDS in eastern China. Our findings showed 9.7% prevalence of anti-T. gondii IgG antibody in HIV/AIDS patients, which was higher than in intravenous drug users (2.2%) and healthy controls (4.7%), while no significant difference was observed in the seroprevalence of anti-Toxoplasma IgM antibody among all participants (P>0.05). Among all HIV/AIDS patients, 15 men (7.7%) and 10 women (15.9%) were positive for anti-T. gondii IgG antibody; however, no significant difference was detected in the seroprevalence of anti-Toxoplasma IgG antibody between males and females. The frequency of anti-Toxoplasma IgG antibody was 8.0%, 13.2%, 5.5%, and 0% in patients with normal immune function (CD4<SUP>+</SUP> T-lymphocyte count ≥500 cells/ml), immunocompromised patients (cell count ≥200 and <500 cells/ml), severely immunocompromised patients (cell count ≥50 and <200 cells/ml), and advanced AIDS patients, respectively (cell count <50 cells/ml), while only 3 immunocompromised patients were positive for anti-T. gondii IgM antibody. The results indicate a high seroprevalence of T. gondii infection in HIV/AIDS patients in eastern China, and a preventive therapy for toxoplasmosis may be given to HIV/AIDS patients based on CD4<SUP>+</SUP> T lymphocyte count.

Modeling and Optimal Design of a Short Primary Double-Sided Linear Induction Motor Considering Both Transverse and Longitudinal End Effects Using Improved Differential Evolution

Wang Hanming,Zhao Jinghong,Guo Guoqiang,Chen Hansi,Xiong Yiyong,Yan Sinian 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

Due to its simple structure, the linear induction motor provides a linear driving force without any intermediate conversion devices. Linear induction motors are gradually used in various applications, including rail transit and the national defense industry. However, linear induction motors are affected by the end-effect phenomenon and suffer from problems such as low efficiencies and low power factors. In this paper, to optimize the performance of short primary double-sided linear induction motors (SP-DLIMs), first, a new analytical model is established based on an equivalent circuit considering both transverse and longitudinal end effects. Second, to analyze the impact of main parameters on the output characteristics of SP-DLIMs, a simple iterative design method (IDM) is presented. Third, a multi-objective optimal design method is proposed to optimize the efficiency, power factor and tooth weight of SP-DLIMs, with proposed design constraints and four different optimization problems. Moreover, an improved differential evolutionary (IDE) algorithm is proposed to optimize the design. A comparison of the results proved that the IDE yielded a competitive performance to those of other advanced heuristic algorithms. Finally, a three-dimensional time-stepping finite-element method was utilized to verify the validity of the optimization results.

Adaptive Notch Filter Based Harmonic Self-Compensated Sliding-Mode Observer for Position Sensorless IPMSM Drives

Guoqiang Zhang,Gaolin Wang,Ronggang Ni,Dianguo Xu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

To suppress the position error harmonic ripples in back electromotive force (EMF) based methods for position sensorless interior permanent magnet synchronous motor (IPSMSM) drives, an adaptive notch filter (ANF) based harmonic self-compensated sliding-mode observer (SMO) is proposed. The inverter nonlinearities and flux spatial harmonics that induce the position error harmonic ripples are analyzed. The back-EMF information containing harmonics can be obtained through SMO, and then the least mean square (LMS) based ANF is adopted to realize back-EMF harmonic detecting and selfcompensating, thus eliminating the position error harmonic ripples. Due to the simple structure, the ANF based harmonic self-compensated SMO can be easily implemented on low-cost microchips with little computational burden. Experiments on a 2.2kW IPMSM sensorless vector controlled drive have been carried out to verify the proposed scheme.

Cenozoic tectonic evolution in the western Qaidam Basin inferred from subsurface data

Yadong Wang,Junsheng Nie,Tao Zhang,Guoqiang Sun,Xin Yang,Yuhu Liu,Xingwang Liu 한국지질과학협의회 2010 Geosciences Journal Vol.14 No.4

It is an agreement that collision of Indian and Asian plates causes uplift of the Tibet Plateau. However, great controversy exists about uplifting history and mechanisms of the Tibetan Plateau. Uplift history of the Tibetan Plateau has been well recorded in the Qaidam Basin, located in the northern margin of the Tibet Plateau. In this paper, we recognize and classify faults recorded by subsurface seismic data in the western Qaidam Basin. In addition, we reconstruct the Cenozoic deformation history of the Qaidam Basin based on balanced section of 5 seismic profiles. The results indicates that 1) Faults in the western Qaidam Basin can be classified as growth faults and non-growth faults, and the growth faults could be divided into three subcategories. 2) According to timing and manner of fault activities, faults and strata in the western Qaidam Basin could be divided into two structural layers: the lower (Lulehe Fm-Xia Youshashan Fm) and the upper (Shang Youshashan Fm-Qigequan Fm) layer. 3) The western Qaidam Basin has experienced two intensive tectonic deformations: the first phase occurs at 43.8−22 Ma (Middle Eocene−Early Miocene), which reached peak at 31.5 Ma (Early Oligocene); the second phase occurred between 14.9 and 0 Ma (Middle Miocene−Present), and the second phase is stronger than the first phase. Recognizing early fault activities confirm previous results that northern Tibet has sensed collision between the India and the Asia shortly after the collision. However, our results here emphasize that the northern Tibet has experienced another phase of shortening and uplift in the late Neogene. It was the two-stage tectonic activities that work together to produce the current Tibetan Plateau.

Controllable Synthesis and Photocatalytic Properties of C-doped BiVO4 with Self-Heterostructure Under Different Light Sources

Yong Wang,Jianfeng Huang,Guoqiang Tan,Jing Huang,Lili Zhang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.1

C-doped BiVO4 with self-heterostructure were synthesized via a facile one-step microwave-hydrothermal route at different reaction temperatures and reaction times. The crystal structure,morphology and photophysical properties of the samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM) and UV-Vis techniques. The photocatalytic properties of the samples were evaluated by the decolorization of rhodamine B under ultraviolet light or simulated visible light irradiation. It was found that pure BiVO4 polyhedrons had a monoclinic structure while C-doped BiVO4 had self-heterostructure with both monoclinic and tetragonal phase. This mixed-phase structure exhibited higher activity than monoclinic structure under ultraviolet light irradiation while monoclinic C-doped BiVO4 had better photocatalytic property under simulated visible light irradiation. The selectivity of the light source with different C-doped BiVO4 self-heterostructures was also discussed in this work.