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Exact tracking control of uncertain non-linear systems with additive disturbance
Zhengqiang Zhang,Park, Ju H.,Hanyong Shao,Zhidong Qi IET 2015 IET CONTROL THEORY AND APPLICATIONS Vol.9 No.5
<P>This study deals with adaptive control of non-linear systems in the strict-feedback form with parametric uncertainties and additive disturbance. The disturbance in the systems is assumed to be bounded. No knowledge of the uncertain parameters, an upper bound of the uncertain parameter vector, a bound of unknown disturbance and the differentiability of the external disturbance is required. Under the weakened assumptions, two continuous robust adaptive control schemes are proposed. In the first control scheme, a modified adaptive backstepping design procedure is proposed to remove overparameterisation. A novel damping term with the estimate of unknown disturbance bound and a positive time-varying integral function are introduced in the control law to counteract the destabilising effects of the external disturbance. In the second scheme, an alternative continuous adaptive controller is designed. Instead of the estimate of the disturbance bound, an adaptive parameter is incorporated into the control design. In both of the two control schemes, the design parameters are freely chosen to improve the control performance. It is proved that the proposed two adaptive control schemes can guarantee that the closed-loop signals are bounded and the output tracking error converges to zero asymptotically in spite of the disturbance. Finally, a numerical example is included to show the effectiveness of the presented control methods.</P>
Adaptive Backstepping Control That Is Equivalent to Tuning Functions Design
Zhengqiang Zhang,Maoli Wang,Yanmei Liu 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.1
In this paper, we present a new adaptive backstepping control design method to solve the overparametrizationproblem in parameter estimation. Unlike the existing schemes, the concept of tuning functionsis not introduced. However, the number of parameter estimates is reduced to be minimal, which is exactly the sameas that of unknown parameters. Subsequently, it is shown that the proposed control schemes are equivalent to thetuning functions design. Two class of common nonlinear systems, that is, parametric strict-feedback system andparametric output-feedback system are employed to illustrate our design procedure.
Electrospun Fibrous Silk Fibroin/Poly(L-Lactic Acid) Scaffold for Cartilage Tissue Engineering
Weiwei Liu,Zhengqiang Li,Lu Zheng,Xiaoyan Zhang,Peng Liu,Ting Yang,Bing Han 한국조직공학과 재생의학회 2016 조직공학과 재생의학 Vol.13 No.5
For successful tissue engineering of articular cartilage, a scaffold with mechanical properties that match those of natural cartilage as closely as possible is needed. In the present study, we prepared a fibrous silk fibroin (SF)/poly(L-lactic acid) (PLLA) scaffold via electrospinning and investigated the morphological, mechanical, and degradation properties of the scaffolds fabricated using different electrospinning conditions, including collection distance, working voltage, and the SF:PLLA mass ratio. In addition, in vitro cell-scaffold interactions were evaluated in terms of chondrocyte adhesion to the scaffolds as well as the cytotoxicity and cytocompatibility of the scaffolds. The optimum electrospinning conditions for generating a fibrous SF/PLLA scaffold with the best surface morphology (ordered alignment and suitable diameter) and tensile strength (~1.5 MPa) were a collection distance of 20 cm, a working voltage of 15 kV, and a SF:PLLA mass ratio of S50P50. The degradation rate of the SF/PLLA scaffolds was found to be determined by the SF:PLLA mass ratio, and it could be increased by reducing the PLLA proportion. Furthermore, chondrocytes spread well on the fibrous SF/PLLA scaffolds and secreted extracellular matrix, indicating good adhesion to the scaffold. The cytotoxicity of SF/PLLA scaffold extract to chondrocytes over 24 and 48 h in culture was low, indicating that the SF/PLLA scaffolds are biocompatible. Chondrocytes grew well on the SF/PLLA scaffold after 1, 3, 5, and 7 days of direct contact, indicating the good cytocompatibility of the scaffold. These results demonstrate that the fibrous SF/PLLA scaffold represents a promising composite material for use in cartilage tissue engineering.
Cheng Tan,Jianying Di,Zhengqiang Zhang,Wing Shing Wong 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.2
This paper investigates the general stabilization issues for continuous-time stochastic dynamics whose input delay and multiplicative noise in control variable exist simultaneously. On the one hand, we present a set of necessary and sufficient conditions for stabilizing the considered stochastic dynamics in mean-square sense. Different from many previous works, one significant innovation is that our control policy is designed as the feedback of an extended state that contains the current available state and some past control information. On the other hand, another important innovation is that we for the first time generalize the notions of critical stabilization and essential destabilization to stochastic time-delay model in terms of spectral analysis technique, while the related necessary and sufficient stabilization conditions are derived respectively.
Delay-Dependent H_∞ Control for Jumping Delayed Systems with Two Markov Processes
Hao Shen,Yuming Chu,Shengyuan Xu,Zhengqiang Zhang 제어·로봇·시스템학회 2011 International Journal of Control, Automation, and Vol.9 No.3
This paper addresses the H_∞ control problem for jumping delayed systems with two separable Markov processes. The objective is to design a controller such that the resulting closed-loop system is exponentially mean-square stable with a given decay rate and satisfies a prescribed H_∞ performance level. A decay-rate-dependent condition is obtained for the existence of admissible controllers in term of linear matrix inequalities. Two numerical examples are presented to demonstrate the effectiveness of the proposed method.
Zhou Jian,Ding Feng,Yang Jiaxuan,Pei Zhengqiang,Wang Chenxu,Zhang Anmin 대한조선학회 2021 International Journal of Naval Architecture and Oc Vol.13 No.1
This paper proposes a decision support model for USVs to improve the accuracy of collision avoidance decision-making. It is formed by Navigation Safety Domain (NSD) and domain-based Collision Risk Index (CRI), capable of determining the collision stage and risk between multiple ships. The NSD is composed of a warning domain and a forbidden domain, which is constructed under the constraints of COLREGs (International Regulations for Preventing Collisions at Sea). The proposed domain based CRI takes the radius of NSD in various encounter situations as threshold parameters. It is found that the value of collision risk in any directions can be calculated, including actual value and risk threshold. A catamaran USV and 6 given vessels are taken as study objects to validate the proposed model. It is found that the judgment of collision stage is accurate and the azimuth range of risk exists can be detected, hence the ships can take direct and effective collision avoidance measures. According to the relation between the actual value of CRI and risk threshold, the decision support rules are summarized, and the specific terms of COLREGs to be followed in each encounter situation are given.
Mbuji Amosi Leonard,Gong Xueyan,Li Fen,Yang Lei,Shi Xueyan,Peng Zhengqiang,Zhang Ying,Wu Shaoying 한국곤충학회 2022 Entomological Research Vol.52 No.5
Cannibalism behaviour in the Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is among of liming factor for mass production of the larvae for laboratory experiment. To understand the change of cannibalism, larvae of 1st, 2nd, and 3rd were used to study cannibalism they were put on the 3rd, 4th, and 5th larvae growth stages in a density of 30, 40, 50, 60, and 70. In this study, the results showed that the functional response of the 3rd -5th instar larvae to the 2nd larvae and the 4th–5th instar larvae to the 3rd larvae and 5th and 6th instar larvae to the 4th larvae fitted well with the Holling II mode. The maximum predation of the 3rd-5th instar larvae on the 2nd instar larvae were 27.17, 74.63, and 232.6 respectively, the maximum predation of the 4th–5th instar larvae on the 3rd instar larvae were 76.92 and 11.82 respectively, and the maximum predation of the 5th–6th instar larvae on the 4th instar larvae were 15.83 and 10.40. The predation of the older larvae to the younger larvae increased with the increase of the density of the younger larvae. This research aims at selecting the minimum number of larvae that will be effective and sustainable for laboratory experiments and minimizing the development of cannibalism in S. frugiperda, reduces crowding for larvae management and promoting healthy larvae. This study provides a pavement of managing larvae ensuring massive indoor larvae rearing to reduce the challenge of inadequate larva for the experiment.
Chengfang Qiao,Xia Gao,Qi Tang,Jianfang Wang,Yulin Gao,Meili Zhang,Zhengqiang Xia,Haitao Han,Chunxin Zhao,Chunsheng Zhou 대한화학회 2020 Bulletin of the Korean Chemical Society Vol.41 No.12
A bifunctional lead(II)-acylhydrazone coordination polymer featuring 3D hydrogen-bonded framework exhibits intense blue luminescence and remarkable inhibitory effect on the fusarium fungi.
Zheng, Qiang,Gong, Tao,Sun, Xun,Zhang, Zhi-Rong The Pharmaceutical Society of Korea 2006 Archives of Pharmacal Research Vol.29 No.12
A triptolide-lysozyme (TP-LZM) conjugate was synthesized to achieve renal specific delivery and to reduce the side effects of triptolide. Triptolide was coupled to lysozyme through succinic via an ester bond with an average coupling degree of 1 mol triptolide per 1 mol lysozyme. The lysozyme can specifically accumulate in the proximal tubular cells of the kidney, making it a potential carrier for targeting drugs to the kidney. The structure of triptolide succinate (TPS) was confirmed by IR, $^{1}H-NMR$, MS and UV. The concentrations of triptolide in various samples were determined by reversed-phase high-performance liquid chromatography (HPLC). In this study, the physicochemical and stability profiles of TP-LZM under various conditions were investgated the stability and releasing profiles of triptolide-lysozyme (TP-LZM) under various conditions. In vitro release trails showed triptolide-lysozyme was relatively stable in plasma (less than 30% of free triptolide released) and could release triptolide quickly in lysosome (more than 80% of free triptolide released) at $37^{\circ}C$ for 24 h. In addition, the biological activities of the conjugate on normal rat kidney proximal tubular cells (NRK52E) were also tested. The conjugate can effectively reduce NO production in the medium of NRK52E induced by lipopolysaccharide (LPS) but with much lower toxicity. These studies suggest the possibility to promote curative effect and reduce its extra-renal toxicity of triptolide by TP-LZM conjugate.