Closed-Loop Bifurcation Analysis for a Novel Moving Mass Flight Vehicle

Zhitao Liu,Changsheng Gao,Jianqing Li,Wuxing Jing 한국항공우주학회 2018 International Journal of Aeronautical and Space Sc Vol.19 No.4

In this paper, nonlinear dynamics properties regarding a novel moving mass flight vehicle with large mass ratio are investigated based on bifurcation theory and continuation methods. Of particular interest is the impact of variation of command angle-of-attack and moving mass parameters on the controlled system. The nonlinear longitudinal dynamics model is established and the controller is designed using Immersion and Invariance method. Bifurcation analysis is conducted both from the prospective of static bifurcation and dynamical bifurcation, results of the closed-loop system are compared with the uncontrolled case. Numerical results obtained from bifurcation diagrams indicate that although the introduction of control system is capable of eliminating unstable regions caused by the variation of moving mass parameters, the change of command angle-of-attack still lead to Hopf bifurcation. Furthermore, analysis of limit cycle branch reveals the consecutive birth of Limit Point of Cycle bifurcation (LPC), then based on which a more detailed nonlinear dynamics process of the closed-loop system is analyzed.

Micro-gap DBD Plasma and Its Applications

( Zhitao Zhang ),( Cheng Liu ),( Mindi Bai ),( Bo Yang ),( Cheng Qi Mao ) 한국동굴학회 2006 동굴 Vol.76 No.-

The Dielectric Barrier Discharge (DBD) is a nonequilibrium gas discharge that is generated in the space between two electrodes, which are separated by an insulating dielectric layer. The dielectric layer can be put on either of the two electrodes or be inserted in the space between two electrodes. If an AC or pulse high voltage is applied to the electrodes that is operated at applied frequency from 50Hz to several MHz and applied voltages from a few to a few tens of kilovolts rms, the breakdown can occur in working gas, resulting in large numbers of micro-discharges across the gap, the gas discharge is the so called DBD. Compared with most other means for nonequilibrium discharges, the main advantage of the DBD is that active species for chemical reaction can be produced at low temperature and atmospheric pressure without the vacuum set up, it also presents many unique physical and chemical process including light, heat, sound and electricity. This has led to a number of important applications such as ozone synthesizing, UV lamp house, CO2 lasers, et al. In recent years, due to its potential applications in plasma chemistry, semiconductor etching, pollution control, nanometer material and large area flat plasma display panels, DBD has received intensive attention from many researchers and is becoming a hot topic in the field of non-thermal plasma.

Micro-gap DBD Plasma and Its Applications

Zhang, Zhitao,Liu, Cheng,Bai, Mindi,Yang, Bo,Mao, Chengqi The Speleological Society 2006 동굴 Vol.76 No.-

The Dielectric Barrier Discharge (DBD) is a nonequilibrium gas discharge that is generated in the space between two electrodes, which are separated by an insulating dielectric layer. The dielectric layer can be put on either of the two electrodes or be inserted in the space between two electrodes. If an AC or pulse high voltage is applied to the electrodes that is operated at applied frequency from 50Hz to several MHz and applied voltages from a few to a few tens of kilovolts rms, the breakdown can occur in working gas, resulting in large numbers of micro-discharges across the gap, the gas discharge is the so called DBD. Compared with most other means for nonequilibrium discharges, the main advantage of the DBD is that active species for chemical reaction can be produced at low temperature and atmospheric pressure without the vacuum set up, it also presents many unique physical and chemical process including light, heat, sound and electricity. This has led to a number of important applications such as ozone synthesizing, UV lamp house, CO2 lasers, et al. In recent years, due to its potential applications in plasma chemistry, semiconductor etching, pollution control, nanometer material and large area flat plasma display panels, DBD has received intensive attention from many researchers and is becoming a hot topic in the field of non-thermal plasma.

Highly Sensitive and Naked Eye Dual-readout Method for ʟ-Cysteine Detection Based on the NSET of Fluorophore Functionalized Gold Nanoparticles

Fu, Xin,Liu, Yuan,Wu, Zhitao,Zhang, He Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.4

A simple, highly sensitive and selective method based on the rhodamine B-covered gold nanoparticle with dual-readout (colorimetric and fluorometric) detection for $\small{L}$-cysteine is proposed. A mechanism is that citrate-stabilized AuNPs were modified with RB by electrostatic interaction, which enables the nanometal surface energy transfer (NSET) from the RB to the AuNPs, quenching the fluorescence. In the presence of $\small{L}$-cysteine, it was used as a competitor in the NSET by the strongly Au-S bonding to release RB from the Au surface and recover the fluorescence, and the red-to-purple color change quickly, which was monitored simply by the naked eye. Under the optimum conditions, the detection limit is as low as 10 nM. The method possessed the advantages of simplicity, rapidity and sensitivity at the same time. The method was also successfully applied to the determination of $\small{L}$-cysteine in human urine samples, and the results were satisfying.

Numerical study for downburst wind and its load on high-rise building

Huang, Guoqing,Liu, Weizhan,Zhou, Qiang,Yan, Zhitao,Zuo, Delong Techno-Press 2018 Wind and Structures, An International Journal (WAS Vol.27 No.2

3D simulations based on an impinging jet were carried out to investigate the flow field of a steady downburst and its effects on a high-rise building by applying the SST k-${\omega}$ turbulence model. The vertical profile of radial wind speed obtained from the simulation was compared with experimental data and empirical models in order to validate the accuracy of the present numerical method. Then wind profiles and the influence of jet velocity and jet height were investigated. Focusing on a high-rise building, the flow structures around the building, pressure distributions on the building surfaces and aerodynamic forces were analyzed in order to enhance the understanding of wind load characteristics on a high-rise building immersed in a downburst.

Influence of Solution Concentrations on Surface Morphology and Wettability of ZnO Thin Films

Jianguo Lv,Changlong Liu,Feng Wang,Zhitao Zhou,Zhenfa Zi,Yuan Feng,Xiaoshuang Chen,Feng Liu,Gang He,Shiwei Shi,Xueping Song,Zhaoqi Sun 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.2

ZnO thin films were grown on silicon substrates using a hydrothermal method. The XRD patterns show that all of the peaks can be attributed to the wurtzite structures of ZnO. The TC value of (002) plane and average crystal size increase first and then decrease with the increase of solution concentration. SEM and AFM results show that many dense hexagonal cylinder particles have been observed on the surface of the thin films, which grown at 0.08 and 0.10 mol/L. The surface roughness of the thin films deposited at 0.06,0.08, 0.10, and 0.12 mol/L are 24.5, 38.3, 32.0, and 39.4 nm, respectively. Surface wettability results show that the preferential orientation along c-axis and surface roughness contribute significantly to the hydrophobicity. The reversible switching between hydrophobicity and hydrophilicity is related to the synergy of the transition of wetting model, surface crystal structure, and surface roughness.

Highly Sensitive and Naked Eye Dual-readout Method for L-Cysteine Detection Based on the NSET of Fluorophore Functionalized Gold Nanoparticles

Xin Fu,Yuan Liu,Zhitao Wu,He Zhang 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.4

A simple, highly sensitive and selective method based on the rhodamine B-covered gold nanoparticle with dual-readout (colorimetric and fluorometric) detection for L-cysteine is proposed. A mechanism is that citratestabilized AuNPs were modified with RB by electrostatic interaction, which enables the nanometal surface energy transfer (NSET) from the RB to the AuNPs, quenching the fluorescence. In the presence of L-cysteine, it was used as a competitor in the NSET by the strongly Au-S bonding to release RB from the Au surface and recover the fluorescence, and the red-to-purple color change quickly, which was monitored simply by the naked eye. Under the optimum conditions, the detection limit is as low as 10 nM. The method possessed the advantages of simplicity, rapidity and sensitivity at the same time. The method was also successfully applied to the determination of L-cysteine in human urine samples, and the results were satisfying.

Excessive retinoic acid inhibit mouse embryonic palate mesenchymal cell growth through involvement of Smad signaling

Zengli Yu,Xiaozhuan Liu,Zhan Gao,Zhitao Li,Jun Yin,Yuchang Tao,Lingling Cui,Zengli Yu 한국통합생물학회 2017 Animal cells and systems Vol.21 No.1

All-trans retinoic acid (atRA), the oxidative metabolite of retinoic acid (RA), is essential for palatogenesis. Overdose RA is capable of inducing cleft palate in mice and humans. Normal embryonic palatal mesenchymal (EPM) cell growth is crucial for shelf growth. Smad signaling is involved in many biological processes. However, it is not much clear if atRA could affect Smad signaling during EPM cells growth. In this study, the timed pregnant mice with maternal administration of 100 mg/kg body weight of RA by gastric intubation were cervical dislocation executed to evaluate growth changes of palatal shelves by hematoxylin and eosin (H&E) staining. At the same time, a primary mouse EPM (MEPM) cell culture model was also established. MEPM cells were treated with atRA (0.1, 0.5, 1, 5 and 10 μM) for 24, 48 and 72 h. The results indicated that the sizes of the shelves were smaller than those in control. AtRA inhibited MEPM cell growth with both increasing concentration and increasing incubation time, especially at 72 h in vitro. Moreover, atRA significantly increased the mRNA and protein expression levels of Smad7 (P < .05), but the mRNA and protein expression levels of PCNA were reduced (P < .05). We also found atRA inhibited phosphorylation of Smad2 compared with untreated group (P < .05). However, the protein and mRNA levels of Smad2 did not change both in atRA-treated and untreated group (P > .05). We demonstrated that RA induced inhibition of MEPM cell growth that could cause cleft palate partly by down-regulation of Smad pathway.

Numerical study for downburst wind and its load on high-rise building

Guoqing Huang,Weizhan Liu,Qiang Zhou,Zhitao Yan,Delong Zuo 한국풍공학회 2018 Wind and Structures, An International Journal (WAS Vol.27 No.2

3D simulations based on an impinging jet were carried out to investigate the flow field of a steady downburst and its effects on a high-rise building by applying the SST k-ω turbulence model. The vertical profile of radial wind speed obtained from the simulation was compared with experimental data and empirical models in order to validate the accuracy of the present numerical method. Then wind profiles and the influence of jet velocity and jet height were investigated. Focusing on a high-rise building, the flow structures around the building, pressure distributions on the building surfaces and aerodynamic forces were analyzed in order to enhance the understanding of wind load characteristics on a high-rise building immersed in a downburst.

Experimental and Numerical Analysis of the Construction Process for the Oblique Cantilevered Steel Reinforced Concrete Structure

Qinglin Tao,Wanyun Yin,Rencai Jin,Feng Yu,Beng Niu,Yi Hu,Zhitao Li,Quanwei Liu,Yuandi Qian,Dongyun Jia 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.5

The oblique cantilevered steel reinforced concrete structure (OCSRCS) which includes members of oblique beam, upright column, and the oblique column is manly applied in Olympic Sports Center Stadium and has the characteristics of large section, long span, and large inclination angle. For the safe and economical construction of the OCSRCS, a new construction method named Self-balancing and Self-supporting Method is proposed to take place of traditional construction method of Full-space Support. In this method, cables are utilized to transfer the lateral pressure and gravity load of concrete in pouring to the embedded steel in the OCSRCS and the platform. For ensure the safety of this method, the fi nite element method is proposed to predict the mechanical behavior of the OCSRCS in construction, and the strain variation of the embedded steel in the OCSRCS during the construction process has also observed by the in-situ experiment. The stress distribution of steel and cables in the OCSRCS is investigated and validated in this paper. The results show that the Self-balancing and Self-supporting Method for the OCSRCS can eff ectively ensures the safety of the construction, and it provides references for the construction of large-scale OCSRCS in engineering.