Prescribed-time Stabilization for a Class of Nonlinear Systems with Control Singularities

Lulu Fu,Ruicheng Ma,Jun Fu 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.2

This paper studies the prescribed-time stabilization of a class of nonlinear systems with control singularities. The settling time is independent of not only the design parameters but also the initial conditions, and can be set according to per our will. By using backstepping, we simultaneously construct a control Lyapunov function (CLF) with singularity and a control law to prescribed-time stabilize the equilibrium point of the studied system in settling time, and avoid all trajectories from crossing the control singularity set. Further, the feasibility region is consistent with the attraction region, and the attraction region is also maximized. That is, the positive invariance condition is achieved. Finally, two examples are presented to illustrate the effectiveness of our proposed method.

Investigation on characteristics of pressure fluctuation in a centrifugal pump with clearance flow

Lulu Zheng,Xiaoping Chen,Wei Zhang,Zu-chao Zhu,Jinglei Qu,Mengmeng Wang,Xiaojie Ma,Xueli Cheng 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.9

Clearance flow has great impact on pressure fluctuation of centrifugal pumps. Numerical calculations are performed to study the pressure fluctuation characteristics of centrifugal pump with wear ring clearance, especially in the regions of interaction between main flow and clearance flow (IMC) and clearance. The accuracy of numerical calculations is illustrated by comparing the experiments of performance and pressure fluctuation. Results show that, in clearance region the pressure fluctuation is still governed by blade passing frequency (f BPF ). Its amplitude of dominate frequency of pressure fluctuation becomes larger as the probe approaches the impeller exit. In IMC region, the pressure fluctuation at impeller outlet is dominated by f BPF . However, the dominate frequency at the entrance of impeller is less than f BPF . In addition, as the flow rate increased, the amplitude of dominate frequency of pressure fluctuation increases at impeller entrance, whereas an inverse trend is observed at wear ring clearance region.

Study on Hot Deformation Behavior and Bending Forging Process of 7075 Aluminum Alloy

Lulu Li,Rui Ma,Jun Zhao,Ruixue Zhai 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.5

7075 aluminum alloy forged elbow has a wide range of application, but its deformation law is very complex. Its forging process parameters are difficult to control, so it is becoming a difficulty in practical production. In this paper, aiming at the forging parameters of 7075 aluminum alloy, the thermal simulation compression tests with different deformation parameters were cleverly designed, and the optimal forming range of 7075 aluminum alloy was obtained by combining theoretical calculation, microstructure and simulation. The results showed that: 7075 aluminum alloy forming process parameters range was 350∘C≤T≤450∘C+0.01/s≤ε˙≤0.78/s, T = 400 °C + 0.78/s≤ε˙≤1.0/s(except 400 °C + 0.1/s). The optimum forging parameters were: forging temperature 420 °C, forging speed 10 mm/s.

Determination and Variation of Core Bacterial Community in a Two- Stage Full-Scale Anaerobic Reactor Treating High-Strength Pharmaceutical Wastewater

( Haijun Ma ),( Lin Ye ),( Haidong Hu ),( Lulu Zhang ),( Lili Ding ),( Hongqiang Ren ) 한국미생물생명공학회(구 한국산업미생물학회) 2017 Journal of microbiology and biotechnology Vol.27 No.10

Knowledge on the functional characteristics and temporal variation of anaerobic bacterial populations is important for better understanding of the microbial process of two-stage anaerobic reactors. However, owing to the high diversity of anaerobic bacteria, close attention should be prioritized to the frequently abundant bacteria that were defined as core bacteria and putatively functionally important. In this study, using MiSeq sequencing technology, the core bacterial community of 98 operational taxonomic units (OTUs) was determined in a twostage upflow blanket filter reactor treating pharmaceutical wastewater. The core bacterial community accounted for 61.66% of the total sequences and accurately predicted the sample location in the principal coordinates analysis scatter plot as the total bacterial OTUs did. The core bacterial community in the first-stage (FS) and second-stage (SS) reactors were generally distinct, in that the FS core bacterial community was indicated to be more related to a higherlevel fermentation process, and the SS core bacterial community contained more microbes in syntrophic cooperation with methanogens. Moreover, the different responses of the FS and SS core bacterial communities to the temperature shock and influent disturbance caused by solid contamination were fully investigated. Co-occurring analysis at the Order level implied that Bacteroidales, Selenomonadales, Anaerolineales, Syneristales, and Thermotogales might play key roles in anaerobic digestion due to their high abundance and tight correlation with other microbes. These findings advance our knowledge about the core bacterial community and its temporal variability for future comparative research and improvement of the two-stage anaerobic system operation.

Reduced-order Observers Design for Unknown Inputs Switched Systems without Strongly Detectable of Subsystems

Ruicheng Ma,Haozhe Pang,Lulu Fu,Yetian Fan 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.4

This paper investigates the reduced-order switched observers for switched linear systems with unknown inputs when none subsystems are strongly detectable under dwell time switching. A time-varying disturbancedecoupling state coordinate transformation is first utilized to decouples the unknown input from a subset of the transformed state coordinates. Secondly, a linear coordinate transformation is constructed to decompose the system state into directly available state component parts and non-direct available state component parts. The existence conditions of the reduced-order switched observers are derived by both restricting the upper bounds and the lower bounds of dwell time, decreasing the energy of switched systems at switching times, and confining the growth of subsystems’ Lyapunov functions, and the reduced-order switched observers are constructed. Stability analysis of switched error dynamics is also presented. Then, the proposed reduced-order switched observers asymptotically converges to the state under the designed dwell time switching signal. Finally, an example confirms the effectiveness of the proposed method.

현직 교사의 일과 학업에의 균형에 대한 질적 사례연구 : 교육학과 대학원생을 중심으로

류루루(Liu, LuLu),이지인(Lee, Jiin),마루오시(Ma, RuoXi),서영주(Seo, Youngjoo) 학습자중심교과교육학회 2022 학습자중심교과교육연구 Vol.22 No.4

목적 본 연구는 대학원에 재학중인 현직 교사의 대학원 생활의 경험을 통해 그들의 일과 학업에 대해 겪은 어려움과 해결법을 파악하고, 현직 교사에 대한 재교육 과정의 시사점을 도출하는 데 그 목적이 있다. 방법 본 연구의 목적을 달성하기 위하여 내러티브 탐구를 활용하였다. 연구 참여자는 국내 A대학의 대학원에 재학중인 현직 교사 6명을 유의적 표집한 후, 반구조화 면담으로 수집된 현장 텍스트를 통해 참여자의 일과 학업의 균형 경험에 관한 이야기를 중심으로 내러티브 시간적 차원에 근거하여 분석하였다. 연구의 타당성을 확보를 위해서는 대화와 협의를 통해 의미를 분석하고 상호 확인하는 과정을 거침으로써 연구자가 주관적인 오류에 빠지지 않도록 주의를 기울였다. 결과 재학중인 현직 교사들의 대학원 진학 동기는 학문에 대한 열정, 진로, 생활에 대한 도움 등으로 나타났다. 그들이 대학원생활 적응 초기 경험하는 어려움은 주로 난이도가 높은 학업과 쓰기가 어려움 논문으로 나타났으며, 일과 학업의 불균형으로 인한 건강상태의 악화, 여가 시간 부족, 직장 생활에 부정적인 영향 등 어려움을 겪고 있었다. 이로 인한 갈등이 생기고 스트레스가 쌓이지만 가족과 친구의 지지, 교수와 직장의 이해와 배려가 일부 교사에게 견디는 힘이 되었다. 그럼에도 불구하고, 일과 학업의 불균형 문제를 해결하기어려움으로 인해 이런 문제를 해결할 수 없는 일부 교사가 학업 포기하든지 휴직을 선택하기도 한다. 결론 대학원에 재학중인 현직 교사가 일과 학업 간의 균형을 잘 잡을 수 있도록 정부와 학교가 같이 협력하여 도움을 줄 수 있는 적절한 교육 방안 마련이 필요하다. Objectives The purpose of this study were to identify the difficulties and solutions experienced in their work and study through the graduate life experiences of in-service teachers attending a graduate school, and offer insights to the Korean universities deriving implications for the re-training process of them. Methods This study explores work-study balance experiences of six in-service teachers attending “A” university graduate school in Busan City, Korea. Using narrative inquiry to elicit their stories in their own voices, the field texts collected from semi-structured interviews were analyzed focusing on critical experiences throughout their work-study balance. Results The results indicate that in-service teachers motivation for entering graduate school was found to be passion for study, career, and help with life. The difficulties they experience in adapting to graduate life were mainly found to be high-level academic and difficult-to-write papers at the beginning. Work-study imbalance caused them to have a lot of life problems, such as poor health, lack of leisure time, negative effects on work life, and this problems lead to conflicts and stress of life. The support of family and friends, understanding and consideration of professors and workplaces, it was a force to hold on to some in-service teachers. However, it is difficult to solve the problem even if the teacher makes his or her own efforts while receiving a lot of external support. Therefore, some in-service teacher who cannot solve these problems may give up their studies or work. Conclusions It is necessary to prepare an appropriate educational plan for the government and schools to cooperate and help in-service teachers attending graduate school so that they can balance work and study well.

Overexpressing fusion proteins of 4-coumaroyl-CoA ligase (4CL) and stilbene synthase (STS) in tobacco plants leading to resveratrol accumulation and improved stress tolerance

Xuancheng He,Feiyan Xue,Lulu Zhang,Hui-Li Guo,Lan-Qing Ma,Mingfeng Yang 한국식물생명공학회 2018 Plant biotechnology reports Vol.12 No.5

Resveratrol (trans-3,4′,5-trihydroxystilbene) is a phytoalexin produced in plants in response to pathogen attack as a part of plant defense response and it is also a highly bioactive substance of pharmaceutical interest. To obtain transgenic plants with a high level of resveratrol, two enzymes in the last two steps of resveratrol synthesis, 4-coumaroyl-CoA ligase (4CL) and stilbene synthase (STS), were fused together by a glycine–serine–glycine (GSG) tripeptide linker, and the 4CL-GSGSTS construct driven by a CaMV35S promoter was transformed into tobacco (Nicotiana benthamiana) by Agrobacteriummediated method. In the transgenic plants, a high resveratrol level was detected (21.05 μg/g fresh weight) by high-pressure liquid chromatography (HPLC), which is higher than previous transgenic plants with only STS gene overexpression. In addition to resistance to pathogen, transgenic plants showed improved tolerance to salt and osmotic stresses, and the lower level of malondialdehyde (MDA) in transgenic plants suggested that resveratrol could protect plant membrane lipid from peroxidation under abiotic stresses.

Deficiency of Follistatin-Like Protein 1 Accelerates the Growth of Breast Cancer Cells at Lung Metastatic Sites

Ying Zhang,Xiaozhou Xu,Ying Yang,Jie Ma,Lulu Wang,Xiangzhi Meng,Bing Chen,Ling Qin,Tao Lu,Yan Gao 한국유방암학회 2018 Journal of breast cancer Vol.21 No.3

Purpose: Follistatin-like protein 1 (FSTL1) is a secreted glycoprotein that has been shown to play a role in various types of cancer. However, the clinical significance and function of FSTL1 in breast cancer have not been reported. We investigated the role of FSTL1 in breast cancer in this study. Methods: Enzyme-linked immunosorbent assays, western blot analysis, and reverse transcription polymerase chain reaction were used to monitor the expression of FSTL1 in breast cancer tissue and in serum samples from breast cancer patients. We employed a 4T1 breast cancer model and Fstl1+/− mice for in vivo studies. Hematoxylin and eosin staining, western blot analysis, and RNA sequencing were used to analyze the effect of FSTL1 on primary tumor growth and lung metastasis. Results: We demonstrated that the expression of FSTL1 is reduced in both the breast cancer tissue and the serum of breast cancer patients. We showed that reduced levels of FSTL1 in serum correlate with elevated expression of Ki-67 and epidermal growth factor receptor (EGFR) in cancer tissues. Moreover, lowered expression of FSTL1 was associated with decreased survival in breast cancer patients. Experiments on the Fstl1+/− mouse model established that FSTL1 deficiency had no effect on primary tumor growth, but increased the lung metastases of breast cancer cells, resulting in reduced survival of tumor-bearing mice. RNA sequencing found significantly reduced expression of Egln3 and increased expression of EGFR in Fstl1+/− mice. Thus, our results suggest that FSTL1 may affect the expression of EGFR through Egln3, inhibiting the proliferation of breast cancer cells at lung metastatic sites. Conclusion: In conclusion, we suggest a suppressor role of FSTL1 in breast cancer lung metastasis. Furthermore, FSTL1 may represent a potential prognostic biomarker and a candidate therapeutic target in breast cancer patients.

Improving Translation of Organization Names Combining Translation Model and Web Mining

Bin Li,Yin Zhou,Ning Ma,Wuqi Liang,Lulu Dong 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.1

Named entity (NE) translation is a fundamental task in machine translation (MT) and cross-language information retrieval (CLIR). Furthermore, Organization name (ON) translation is the most complex among all the NEs. A novel system for translating ONs from Chinese to English, with a translation model and web resources, is proposed. Firstly, we built a translation model with Chunk. Then query expansion was adopted with the translation model and term-subject co-occurrence. Thirdly, we extracted the Chinese Organization names with English sentences using the method of frequency shifting and adjacency information to find English fragments as translation candidates. Finally, we found the best translation by computing the trustworthiness of all candidates. The experimental results showed that the approach returned a better performance than machine translation-based systems.

Ferulic acid protects cardiomyocytes from TNF-a/cycloheximide-induced apoptosis by regulating autophagy

Chunxiao Li,Lu Chen,Min Song,Zhirui Fang,Lusha Zhang,Joel Wake Coffie,Liyuan Zhang,Lulu Ma,Qianyi Wang,Wenjie Yang,Leyu Fang,Shaoxia Wang,Xiumei Gao,Hong Wang 대한약학회 2020 Archives of Pharmacal Research Vol.43 No.8

Acute myocardial infarction (AMI) resultsin irreversible cardiac cell damage or death because ofdecreased blood fl ow to the heart. Apoptosis plays an importantrole in the process of tissue damage after myocardialinfarction (MI), which has pathological and therapeuticimplications. Ferulic acid (FA) is a phenolic acid endowedwith strong antioxidative and cytoprotective activities. Thepresent study aimed to investigate whether FA protectscardiomyocytes from apoptosis by regulating autophagy,which is a cellular self-digestion process, and one of thefi rst lines of defense against oxidative stress. Apoptosis wasinduced by TNF-α (10 ng/mL) and cycloheximide (CHX,5 μg/mL) in rat H9c2 cardiomyocytes. FA-inhibited TNF-α/CHX-induced apoptosis was determined by the quantifi cationof TUNEL-positive cells, and the eff ect was associatedwith decreased ROS production and inhibited caspase3activation. FA treatment enhanced autophagy and increasedautophagy-associated protein expression, leading to an inhibitionof mTOR signaling. When co-treated with 3-methyladenine(3-MA), an autophagy inhibitor, the anti-apoptoticeff ect of FA was attenuated. In an in vivo mouse MI model,FA treatment decreased the apoptotic cell number, reducedinfarct size, and improved cardiac performance, as determinedby histological and echocardiographic assessments. Taken collectively, these results suggest that FA could protectcardiomyocytes from apoptosis by enhancing autophagy.