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Practical finite-time event-triggered control of underactuated surface vessels in presence of false data injection attacks

Chen Liping, Sun Minghua, Wang Li

Polish Maritime Research

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2024

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nr 1

114--126

EN

The results of studies on a trajectory-tracking problem affected by false data injection attacks (FDIAs) and internal and external uncertainties are presented in this paper. In view of the FDIAs experienced by the system, we compensate for the serious navigation deviation caused by malicious attacks by designing an online approximator. Next, we study the internal and external uncertainties introduced by environmental factors, system parameter fluctuations, or sensor errors, and we design adaptive laws for these uncertainties to approximate their upper bounds. To further enhance the response velocity and stability of the system, we introduce finite-time technology to ensure that the unmanned underactuated surface vessels (USVs) reach the predetermined trajectory-tracking target within finite time. To further reduce the update frequency of the controller, we introduced event-triggered control (ETC) technology. This saves the system’s communication resources and optimizes the system. Through Lyapunov stability theory, a strict and complete stability analysis is provided for the control scheme. Finally, the effectiveness of the control scheme is verified using two sets of simulations.

2

LC-MS/MS method assay for simultaneous determination of the pretomanid and pyrazinamide in rat plasma by LC-MS/MS: Assessment of pharmacokinetic drug-drug interaction study

Huang Tao, Wang Li, Wang Fang, Shen Xin, Wang Libin

Acta Chromatographica

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2024

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Vol. 36, no. 1

7--13

EN

In the present study, an LC-MS/MS method allowing to quantify pretomanid and pyrazinamide simultaneously in rat plasma was developed. Chromatographic separation was achieved on an Agilent Eclipse plus C18 column (100 mm × 2.1 mm, 3.5 μm; Agilent, USA) and maintained at 30 °C. Multiple reaction monitoring (MRM) using positive-ion ESI mode to monitor ion transitions of m/z 360.1 → m/z 175.1 for pretomanid, m/z 124.1 → m/z 81.0 for pyrazinamide, m/z 172.1 → m/z 128.1 for metronidazole (IS). The calibration curves showed good linear relationships over the concentration range of 50–7,500 ng mL⁻¹ for pretomanid and 500–75,000 ng mL⁻¹ for pyrazinamide. The precision and accuracy were below 15% and within ±15% of the nominal concentrations, respectively. The selectivity, recovery and matrix effect of this method were all within acceptable limits of bioanalytics. The method was applied to the analysis of plasma samples from pharmacokinetic studies in rats. The results show that the main pharmacokinetic parameters of pyrazinamide, namely, T max , t1/2, and AUC(0–t), decreased in the combined group than in the alone group.

3

Clogging in vertical flow constructed wetlands : causes for clogging and influence of decontamination

Xu QiaoLing, Wang Li, Wang Ping, Wen XueYuan, Zhang Feng

Ecological Chemistry and Engineering. S

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2022

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Vol. 29, nr 1

65--75

EN

With the continuous operation of constructed wetlands, substrate clogging is issue. In order to solve the problem, there is practical significance to understand the causes for clogging in constructed wetlands. Two pilot-scale vertical flow constructed wetlands were established, namely, CW-B and CW-C. By studying the relationship between the accumulation of different substances and the banked-up water area, it was found that the accumulation of non-filter substances and total solids was an important reason for the clogging of the substrate, and the accumulation degree of non-filter inorganic substances was more obvious than that of non-filter organic substances, and the blockage was mainly located in the 10-20 cm layer. In the vertical flow constructed wetland with river sand as the main substrate, water accumulation will occur when the content of total solid and non-filter substances exceeds 67.233 g and 101.228 g per cubic meter of substrate, respectively. Therefore, it is important to pay attention to the substrate particle size matching of 0-20 cm layer to reduce the clogging in the vertical flow constructed wetland. The clogging has little effect on chemical oxygen demand (COD) removal, but great effect on total phosphorus (TP) removal. Compared with the control wetland (CW-C), the biomass content in the CW-B with biochar increased by 334.26 nmol P/g, which can improve the removal efficiency of total nitrogen (TN) and total phosphorus (TP), but also increase the risk of clogging in the vertical flow constructed wetland. Future research should try to combine the anti-blocking research results of biochar constructed wetlands to improve the purification effect, which is of great significance to promote the sustainable development of constructed wetlands.

4

Investigation of steel wire mesh reinforcement method for 3D concrete printing

Liu Miao, Zhang Qiyun, Tan Zhendong, Wang Li, Li Zhijian, Ma Guowei

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 1

406--423

EN

3D concrete printing has received widespread attention and been developed for an increasing number of applications. However, a major challenge facing this technology is an effective way to introduce reinforcement into continuously deposited cementitious material. In this study, different layers of steel wire meshes (SWM) are employed to reinforce the 3D printed structures to improve mechanical capacities. Both destructive (bending, compression and splitting) and non-destructive (using electro-mechanical impedance) tests are employed to characterize the impact of this reinforcement method. The damage accumulation process is measured through the smart PZT patches based on the electro-mechanical impedance method. The results indicate that reinforced 3D-printed components with SWM change their failure modes from brittle to ductile. The peak loads are increased by 59.2–173.3% and the deflection capacity can be increased by more than 11 times than the non-reinforced one. Different mechanical responses of print and cast samples under compression are studied. The splitting tensile strength of wire mesh reinforced concrete is also measured, which is 43.7% higher than the non-reinforced sample. The calculating methods of the cracking moment and ultimate moment of steel wire mesh reinforced 3D printed concrete are presented. Comparison between the calculated and the experimental results verifies the effectiveness in predicting the ultimate moment. Experimental results show that it is feasible and effective to employ steel wire mesh for strength and toughness enhancement of 3D printed structures.

5

Mechanical behaviors of 3D printed lightweight concrete structure with hollow section

Wang Li, Jiang Hailong, Li Zhijian, Ma Guowei

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 1

219--235

EN

A practical revolution in construction could be realized by combining the potential of 3D concrete printing with lightweight cementitious materials to fabricate adeptly hollow structures. In this study, five concrete mixtures with different replacement rates of lightweight ceramsite sand to silica sand are prepared for extrusion-based 3D printability evaluation. To reduce the water absorption induced shrinkage and micro-cracks, the ceramsite sands were coated with polyvinyl alcohol. An optimized cementitious material was identified by harmonizing the fresh properties to the continuous printing process. Cubic and beam elements with four different types of interior hollow structures were designed and 3D printed based on the optimized lightweight mixture. The interior structures include cellular-shaped structure, truss-like structure, lattice-shaped structure with a square topology, as well as gridding shaped structure with triangle topology. The mechanical capacities of the printed samples were measured and evaluated by compressive tests for the cubic samples and four-points flexural bending tests for the beam specimens. Basing on the results, the rectangular lattice hollow structure demonstrates the best mechanical resistance to compression and the truss-shaped prism structure ensues the highest flexural properties. The stress distribution and failure process were also explored through discrete element method.