Output Feedback Stabilization of Stochastic Nonlinear Time-varying Delay Systems with Unknown Output Function

Mengmeng Gao,Junsheng Zhao,Jianwei Xia,Zong-Yao Sun 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.9

This paper addresses the problem of output feedback stabilization for stochastic nonlinear time-varying delay systems with an unknown output function. A remarkable feature of the system to be considered is the simultaneous presence of a continuous unknown sensitivity function and the stochastic disturbances, which have not been treated together before. A new observer is designed by using a dynamic gain without using the information on unknown time-varying delay and nonlinearities. With the aid of the observer, an output feedback controller is constructed by the stochastic double-domination method, where two gains are used to handle the unknown output function and nonlinearities. The performance of the system is analyzed in detail via two integral Lyapunov functions. Finally, the efficiency of the control strategy is illustrated by a simulation example.

The Effect of Flow Rate of a Short Sleeve Air Ventilation Garment on Torso Thermal Comfort in a Moderate Environment

Mengmeng Zhao,Faming Wang,Chuansi Gao,Zhaoli Wang,Jun Li 한국섬유공학회 2022 Fibers and polymers Vol.23 No.2

In recent years, air ventilation garments (AVG) have been reported effective to improve thermal comfort. In thisstudy, an AVG incorporated with small fans was investigated on torso thermal comfort in moderate environment (Ta=25 oC,RH=50 %). Eight female subjects walked on the treadmill at a speed of 4 km·h-1 for 30 min and then rested for another30 min. During the whole test protocol, the AVG was worn in three conditions of flow rates to examine which flow rate wasthe best choice to keep thermal comfort: fans off with no air ventilation (a controlled condition, CON), low flow rate (12 l/s,LOW) and high flow rate (20 l/s, HIGH). Results showed that HIGH made significantly lowered local skin temperature of theabdomen, scapula and the lower back (p<0.05). The mean torso skin temperature in CON, LOW and HIGH in the last 5 minin the exercising stage was 32.3, 30.2 and 29.2 oC, respectively and it was 32.1, 29.5 and 28.2 oC, respectively in the restingstage. HIGH significantly mitigated thermal sensation in the 40 and 50th min (p<0.05), whereas it produced cool andunpleasant thermal sensation in the resting stage. In the whole test scenario, LOW produced the best torso thermal comfort. The low flow rate of ventilation (12 l/s) should be recommend and used in such a moderate environment to maintain torsothermal comfort.

Auto-reconstruction of Shredded Document based on Matching Models

Mengmeng Yu,Pinjie Ye,Shuoping Wang,Honghao Gao 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.12

Shredding auto-reconstruction is a hot research topic in pattern recognition. The research progress can produce certain effect to various fields. The purpose of this paper is to study shredding auto-reconstruction based on regular shredded document from shredders, to obtain a practical and efficient splicing algorithm to auto- reconstruction of strip shaped shredded text documents and block shapedshredded text documents. For strips, this paper uses the pretreatment, the similarity matching model, combined with the optimalHamilton path algorithm, for which we get a good result with 100% correct rate and no human intervention. For blocks, first, this paper pretreats the fragments. And then uses the row cluster model to divide all debris to some rows, and then uses the similarity model with direct reverse matching model to achieve the shredding auto-restore in different rows. At last, we use line spacing matching model to get the result that has a high correct rate reaching to 90% with little human intervention. In this paper, the design of some algorithms is original. Combined with the present feasible algorithm, we get an ideal result.

Distributed Fuzzy Resilient Tracking for Nonlinear MASs Under DoS Attacks

Shu-Huan Gao,Mengmeng Chen,Chao Deng 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.10

In this paper, the distributed fuzzy resilient tracking problem for a class of second-order nonlinear multiagent systems (MASs) under denial-of-service (DoS) attacks is addressed. Compared with the existing distributed fuzzy tracking results, a more general class of second-order MASs with DoS attacks under combined output observable situation are considered in this paper. Under DoS attacks, the second-order derivative of the traditional distributed observer does not exist, while this signal is necessary to solve the distributed fuzzy tracking problem for second-order MASs when using the backstepping method. To solve the problem, a hierarchical control method that consists of a cooperative resilient observer and a distributed controller is proposed. Specifically, a new distributed resilient observer state with a second-order derivative and also the function of defending network attacks is designed based on a combined output observable condition. By using the backstepping technique, decentralized fuzzy adaptive resilient controllers are designed to achieve distributed tracking under DoS attacks. It is shown that the distributed fuzzy resilient tracking problem can be solved under our designed method. Finally, second-order nonlinear MASs are provided to verify the effectiveness of our method.

A Method for Estimating the Transient Response Time of Turbochargers

Chenfang Wang,Mengmeng Ou,Xiang Gao,Weilin Zhuge,Yangjun Zhang 한국유체기계학회 2023 International journal of fluid machinery and syste Vol.16 No.3

Myocardial Blood Flow Quantified by Low-Dose Dynamic CT Myocardial Perfusion Imaging Is Associated with Peak Troponin Level and Impaired Left Ventricle Function in Patients with ST-Elevated Myocardial Infarction

Jingwei Pan,Mingyuan Yuan,Mengmeng Yu,Yajie Gao,Chengxing Shen,Yining Wang,Bin Lu,Jiayin Zhang 대한영상의학회 2019 Korean Journal of Radiology Vol.20 No.5

Objective: To investigate the association of myocardial blood flow (MBF) quantified by dynamic computed tomography (CT) myocardial perfusion imaging (MPI) with troponin level and left ventricle (LV) function in patients with ST-segment elevated myocardial infarction (STEMI). Materials and Methods: Thirty-five STEMI patients who successfully had undergone reperfusion treatment within 1 week of their infarction were consecutively enrolled. All patients were referred for dynamic CT-MPI. Serial high-sensitivity troponin T (hs-TnT) levels and left ventricular ejection fraction (LVEF) measured by echocardiography were recorded. Twenty-six patients with 427 segments were included for analysis. Various quantitative parameters derived from dynamic CT-MPI were analyzed to determine if there was a correlation between hs-TnT levels and LVEF on admission and again at the 6-month mark. Results: The mean radiation dose for dynamic CT-MPI was 3.2 ± 1.1 mSv. Infarcted territories had significantly lower MBF (30.5 ± 7.4 mL/min/100 mL versus 73.4 ± 8.1 mL/min/100 mL, p < 0.001) and myocardial blood volume (MBV) (2.8 ± 0.9 mL/100 mL versus 4.2 ± 1.1 mL/100 mL, p = 0.044) compared with those of reference territories. MBF showed the best correlation with the level of peak hs-TnT (r = -0.682, p < 0.001), and MBV showed a moderate correlation with the level of peak hs-TnT (r = -0.437, p = 0.026); however, the other parameters did not show any significant correlation with hs-TnT levels. As for the association with LV function, only MBF was significantly correlated with LVEF at the time of admission (r = 0.469, p = 0.016) and at 6 months (r = 0.585, p = 0.001). Conclusion: MBF quantified by dynamic CT-MPI is significantly inversely correlated with the level of peak hs-TnT. In addition, patients with lower MBF tended to have impaired LV function at the time of their admission and at 6 months.

A Survey on Organization and Positioning of Nodes in Wireless Sensor Network

Xinyi Tan,Fuquan Zhang,MengMeng Shi,Demin Gao,Yunfei Liu 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.11

Wireless sensor network has a rapid growth in both science research and commercial development as well as been widely used in a variety of realms. Facing different kinds of challenging issues of WSNs, the deployment of nodes stands out for it has a critical influence on area or target coverage, network connectivity, network lifetime, etc. This paper explores classifications of node and deployment strategies from different angles, weighing their pros and cons and analyzing its impacts on the performance of a WSN.

Patterning-Induced Ferromagnetism of Fe₃GeTe₂ van der Waals Materials beyond Room Temperature

Li, Qian,Yang, Mengmeng,Gong, Cheng,Chopdekar, Rajesh V.,N’Diaye, Alpha T.,Turner, John,Chen, Gong,Scholl, Andreas,Shafer, Padraic,Arenholz, Elke,Schmid, Andreas K.,Wang, Sheng,Liu, Kai,Gao, Nan,Admas American Chemical Society 2018 NANO LETTERS Vol.18 No.9

<P>Magnetic van der Waals (vdW) materials have emerged as promising candidates for spintronics applications, especially after the recent discovery of intrinsic ferromagnetism in monolayer vdW materials. There has been a critical need for tunable ferromagnetic vdW materials beyond room temperature. Here, we report a real-space imaging study of itinerant ferromagnet Fe<SUB>3</SUB>GeTe<SUB>2</SUB> and the enhancement of its Curie temperature well above ambient temperature. We find that the magnetic long-range order in Fe<SUB>3</SUB>GeTe<SUB>2</SUB> is characterized by an unconventional out-of-plane stripe-domain phase. In Fe<SUB>3</SUB>GeTe<SUB>2</SUB> microstructures patterned by a focused ion beam, the out-of-plane stripe domain phase undergoes a surprising transition at 230 K to an in-plane vortex phase that persists beyond room temperature. The discovery of tunable ferromagnetism in Fe<SUB>3</SUB>GeTe<SUB>2</SUB> materials opens up vast opportunities for utilizing vdW magnets in room-temperature spintronics devices.</P> [FIG OMISSION]</BR>

Research progress on hydrogel-based drug therapy in melanoma immunotherapy

( Wei He ),( Yanqin Zhang ),( Yi Qu ),( Mengmeng Liu ),( Guodong Li ),( Luxiang Pan ),( Xinyao Xu ),( Gege Shi ),( Qiang Hao ),( Fen Liu ),( Yuan Gao ) 생화학분자생물학회 2024 BMB Reports Vol.57 No.2

Melanoma is one of the most aggressive skin tumors, and conventional treatment modalities are not effective in treating advanced melanoma. Although immunotherapy is an effective treatment for melanoma, it has disadvantages, such as a poor response rate and serious systemic immune-related toxic side effects. The main solution to this problem is the use of biological materials such as hydrogels to reduce these side effects and amplify the immune killing effect against tumor cells. Hydrogels have great advantages as local slow-release drug carriers, including the ability to deliver antitumor drugs directly to the tumor site, enhance the local drug concentration in tumor tissue, reduce systemic drug distribution and exhibit good degradability. Despite these advantages, there has been limited research on the application of hydrogels in melanoma treatment. Therefore, this article provides a comprehensive review of the potential application of hydrogels in melanoma immunotherapy. Hydrogels can serve as carriers for sustained drug delivery, enabling the targeted and localized delivery of drugs with minimal systemic side effects. This approach has the potential to improve the efficacy of immunotherapy for melanoma. Thus, the use of hydrogels as drug delivery vehicles for melanoma immunotherapy has great potential and warrants further exploration.