Cooperative Guidance Law for Multiple Near Space Interceptors with Impact Time Control

GUO Chao,LIANG Xiao-Geng 한국항공우주학회 2014 International Journal of Aeronautical and Space Sc Vol.15 No.3

We propose a novel cooperative guidance law design method based on the finite time disturbance observer (FTDO) for multiple near space interceptors (NSIs) with impact time control. Initially, we construct a cooperative guidance model with head pursuit, and employ the FTDO to estimate the system disturbance caused by target maneuvering. We subsequently separate the cooperative guidance process into two stages, and develop the normal acceleration command based on the super-twisting algorithm (STA) and disturbance estimated value, to ensure the convergence of the relative distance. Then, we also design the acceleration command along the line-of-sight (LOS), based on the nonsingular fast terminal sliding mode (NFTSM) control, to ensure that all the NSIs simultaneously hit the target. Furthermore, we prove the stability of the closedloop guidance system, based on the Lyapunov theory. Finally, our simulation results of a three-to-one interception scenario show that the proposed cooperative guidance scheme makes all the NSIs hit the target at the same time.

Guidance Law for Near Space Interceptor based on Block Backstepping Sliding Mode and Extended State Observer

GUO Chao,LIANG Xiao-Geng 한국항공우주학회 2014 International Journal of Aeronautical and Space Sc Vol.15 No.2

This paper proposes a novel guidance law based on the block backstepping sliding mode control and extended state observer (ESO), which also takes into account the autopilot dynamic characteristics of the near space interceptor (NSI), and the impact angle constraint of attacking the maneuvering target . Based on the backstepping control approach, the target maneuvers and the parameter uncertainties of the autopilot are regarded as disturbances of the outer loop and inner loop, respectively. Then, the ESO is constructed to estimate the target acceleration and the inner loop disturbance, and the block backstepping sliding model guidance law is employed, based on the estimated disturbance value. Furthermore, in order to avoid the “explosion of complexity” problem, first-order low-pass filters are also introduced, to obtain differentiations of the virtual control variables. The stability of the closed-loop guidance system is also proven, based on the Lyapunov theory. Finally, simulation results demonstrate that the proposed guidance law can not only overcome the influence of the autopilot dynamic delay and target maneuvers, but also obtain a small miss distance.

Disturbance-Observer-Based Robust H<SUB>∞</SUB> Switching Tracking Control for Near Space Interceptor

GUO Chao,LIANG Xiao-Geng 한국항공우주학회 2014 International Journal of Aeronautical and Space Sc Vol.15 No.2

A novel robust H∞ switching tracking control design method with disturbance observer is proposed for the near space interceptor (NSI) with aerodynamic fins and reaction jets. Initially, the flight envelop of the NSI is divided into small subregions, and a slow-fast loop polytopic linear parameter varying (LPV) model is proposed, to approximate the nonlinear dynamic of the NSI, based on the Jacobian linearization and Tensor-Product (T-P) model transformation approach. A disturbance observer is then constructed, to estimate the modeled disturbance. Subsequently, based on the descriptor system method, a robust switching controller is developed, to ensure that the closed-loop descriptor system is stable with a desired H∞ disturbance attenuation level. Furthermore, the outcome of the proposed switching tracking control problem is formulated as a set of linear matrix inequalities (LMIs). Finally, simulation results demonstrate the effectiveness of the proposed design method.

A Novel Strategy for Thermostability Improvement of Trypsin Based on N-Glycosylation within the Ω-Loop Region

( Chao Guo ),( Ye Liu ),( Haoran Yu ),( Kun Du ),( Yiru Gan ),( He Huang ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.6

The Ω-loop is a nonregular and flexible structure that plays an important role in molecular recognition, protein folding, and thermostability. In the present study, molecular dynamics simulation was carried out to assess the molecular stability and flexibility profile of the porcine trypsin structures. Two Ω-Loops (fragment 57-67 and fragment 78-91) were confirmed to represent the flexible region. Subsequently, glycosylation site-directed mutations (A73S, N84S, and R104S) were introduced within the Ω-loop region and its wing chain based on its potential N-glycosylation sites (Asn-Xaa-Ser/Thr consensus sequences) and structure information to improve the thermostability of trypsin. The result demonstrated that the half-life of the N84S mutant at 50°C increased by 177.89 min when compared with that of the wild-type enzyme. Furthermore, the significant increase in the thermal stability of the N84S mutant has also been proven by an increase in the Tm values determined by circular dichroism. Additionally, the optimum temperatures of the wild-type enzyme and the N84S mutant were 75°C and 80°C, respectively. In conclusion, we obtained the thermostability-improved enzyme N84S mutant, and the strategy used to design this mutant based on its structural information and N-linked glycosylation modification could be applied to engineer other enzymes to meet the needs of the biotechnological industry.

Nonlinear Model Predictive Control for Near-Space Interceptor Based on Finite Time Disturbance Observer

Chao Guo,Chen Song,Yu-Jie Zhao,Jun-Wei Wang 한국항공우주학회 2018 International Journal of Aeronautical and Space Sc Vol.19 No.4

This paper proposes a novel nonlinear model predictive control design method based on the finite time disturbance observer (FTDO) and dynamic control allocation (DCA) algorithm for the near-space interceptor (NSI). First, the FTDO is introduced to estimate the mismatched system disturbance. The nonlinear model predictive control scheme based on the estimation value is proposed to obtain the virtual control command, and the mismatched disturbance can be effectively removed from the output channels of the NSI by designing a feed-forward disturbance compensation term with an appropriate compensation gain matrix. Moreover, a new DCA method is given to distribute the above virtual control command among the corresponding actuators (reaction jets and aerodynamic fins). Finally, numerical simulations illustrate that the proposed control scheme can track the command signal with high precision and have strong robustness against the mismatched disturbance.

A Novel Strategy for Thermostability Improvement of Trypsin Based on N-Glycosylation within the Ω-Loop Region

Guo, Chao,Liu, Ye,Yu, Haoran,Du, Kun,Gan, Yiru,Huang, He The Korean Society for Microbiology and Biotechnol 2016 Journal of microbiology and biotechnology Vol.26 No.7

The Ω-loop is a nonregular and flexible structure that plays an important role in molecular recognition, protein folding, and thermostability. In the present study, molecular dynamics simulation was carried out to assess the molecular stability and flexibility profile of the porcine trypsin structures. Two Ω-Loops (fragment 57-67 and fragment 78-91) were confirmed to represent the flexible region. Subsequently, glycosylation site-directed mutations (A73S, N84S, and R104S) were introduced within the Ω-loop region and its wing chain based on its potential N-glycosylation sites (Asn-Xaa-Ser/Thr consensus sequences) and structure information to improve the thermostability of trypsin. The result demonstrated that the half-life of the N84S mutant at 50℃ increased by 177.89 min when compared with that of the wild-type enzyme. Furthermore, the significant increase in the thermal stability of the N84S mutant has also been proven by an increase in the T_m values determined by circular dichroism. Additionally, the optimum temperatures of the wild-type enzyme and the N84S mutant were 75℃ and 80℃, respectively. In conclusion, we obtained the thermostability-improved enzyme N84S mutant, and the strategy used to design this mutant based on its structural information and N-linked glycosylation modification could be applied to engineer other enzymes to meet the needs of the biotechnological industry.

Elevated Expression of Nuclear Protein Kinase CK2α as a Poor Prognosis Indicator in Lymph Node Cancerous Metastases of Human Thyroid Cancers

Guo, Miao,Liu, Chao,Qi, Feng-Jie,Zhang, Xiu-Mei,Ren, Li-Li,Liu, Yi-Meng,Meng, Zhi-Chao,Zhu, Zhi-Tu,Xiao, Jian-Ying Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.17

Aim: To investigate the expression of protein kinase $CK2{\alpha}$ ($CK2{\alpha}$) in human thyroid disease and its relationship with thyroid cancer metastasis. Materials and Methods: Using immunohistochemistry we measured the expression of $CK2{\alpha}$ in 76 benign and malignant human thyroid cancer tissues, including 10 pairs of papillary carcinoma tissues with or without lymph node cancerous metastasis and similarly 10 pairs of lymph nodes. Results: The expression of $CK2{\alpha}$ was found to be higher in thyroid carcinoma cases (papillary carcinoma, follicular carcinoma, anaplastic carcinoma and medullary carcinoma) than in ones such as chronic lymphocytic thyroiditis, nodular goiter and adenoma. These findings were also confirmed by RT-PCR and Western blotting. More strikingly, elevated expression of $CK2{\alpha}$ in thyroid papillary carcinoma tissues was not only significantly associated with lymph node cancerous metastasis and clinical stage of thyroid cancers; but also correlated with epithelial-mesenchymal transition (EMT) and high tenascin C (TNC) expression. In addition, EMT and high TNC expression in thyroid carcinoma tissues was significantly associated with lymph node cancerous metastasis. Conclusions: Elevated expression of nuclear $CK2{\alpha}$ is a poor prognosis indicator in lymph node cancerous metastasis of human thyroid cancers.

YAP/TAZ-Mediated Upregulation of GAB2 Leads to Increased Sensitivity to Growth Factor–Induced Activation of the PI3K Pathway

Wang, Chao,Gu, Chao,Jeong, Kang Jin,Zhang, Dong,Guo, Wei,Lu, Yiling,Ju, Zhenlin,Panupinthu, Nattapon,Yang, Ji Yeon,Gagea, Mihai (Mike),Ng, Patrick Kwok Shing,Zhang, Fan,Mills, Gordon B. American Association for Cancer Research 2017 Cancer Research Vol.77 No.7

<P>Interactions between HIPPO, YAP/TAZ, and the PI3K/AKT pathway may be therapeutically targetable, providing new approaches to treating endometrial cancers and other cancers where the HIPPO pathway is a core oncogenic driver.</P><P>The transcription regulators YAP and TAZ function as effectors of the HIPPO signaling cascade, critical for organismal development, cell growth, and cellular reprogramming, and YAP/TAZ is commonly misregulated in human cancers. The precise mechanism by which aberrant YAP/TAZ promotes tumor growth remains unclear. The HIPPO tumor suppressor pathway phosphorylates YAP and TAZ, resulting in cytosolic sequestration with subsequent degradation. Here, we report that the PI3K/AKT pathway, which is critically involved in the pathophysiology of endometrial cancer, interacts with the HIPPO pathway at multiple levels. Strikingly, coordinate knockdown of YAP and TAZ, mimicking activation of the HIPPO pathway, markedly decreased both constitutive and growth factor–induced PI3K pathway activation by decreasing levels of the GAB2 linker molecule in endometrial cancer lines. Furthermore, targeting YAP/TAZ decreased endometrial cancer tumor growth <I>in vivo</I>. In addition, YAP and TAZ total and phosphoprotein levels correlated with clinical characteristics and outcomes in endometrial cancer. Thus, YAP and TAZ, which are inhibited by the HIPPO tumor suppressor pathway, modify PI3K/AKT pathway signaling in endometrial cancer. The cross-talk between these key pathways identifies potential new biomarkers and therapeutic targets in endometrial cancer. <I>Cancer Res; 77(7); 1637–48. ©2017 AACR</I>.</P>

중국 관광객의 사회적 지위가 지각된 가치, 지각된 위험, 관광만족도 및 관광행동의도에 미치는 영향: 부산지역 방문객을 중심으로

곽초(Guo, Chao),원철식(Won, Chol-Shik) 한국관광레저학회 2021 관광레저연구 Vol.33 No.1

Protective effect of acacetin on sepsis-induced acute lung injury via its anti-inflammatory and antioxidative activity

Li-chao Sun,Hong-bo Zhang,Cheng-Dong Gu,Shi-Dong Guo,Gang Li,Rui Lian,Yao Yao,Guo-qiang Zhang 대한약학회 2018 Archives of Pharmacal Research Vol.41 No.12

Sepsis is a clinical syndrome with no effective protective or therapeutic treatments. Acacetin, a natural flavonoid compound, has anti-oxidative and anti-inflammatory effects which can potentially work to reduce sepsis. We investigated the potential protective effect of acacetin on sepsis-induced acute lung injury (ALI) ALI and dissect out the underlying mechanisms. Mice were divided into five groups: a sham group, a sepsis-induced ALI group, and three sepsis groups pre-treated with 20, 40, and 80 mg/kg body weight of acacetin. We found that acacetin significantly attenuated sepsis-induced ALI, in histological examinations and lung edema. Additionally, acacetin treatment decreased protein and inflammatory cytokine concentration and the number of infiltrated inflammatory cells in BALF compared with that in the non-treated sepsis mice. Pulmonary myeloperoxidase (MPO) activity was lower in the acacetin-pre-treated sepsis groups than in the sepsis group. The mechanism underlying the protective effect of acacetin on sepsis is related to the regulation of certain antioxidation genes, including inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), superoxide dismutases (SODs), and heme oxygenase 1 (HO-1).Taken together, our results indicate that acacetin pre-treatment inhibits sepsis-induced ALI through its anti-inflammatory and antioxidative activity, suggesting that acacetin may be a potential protective agent for sepsis-induced ALI.