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ANovel Non-Isolated Cubic dC-dC Converter with high Voltage Gain for Renewable Energy Power Generation System

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Energy Engineering 2024年第1期121卷 221-241页

作者： Qin Yao Yida zeng Qingui Jia School of Electrical Engineering Southwest Jiaotong UniversityChengdu610036China

In recent years,switched inductor(SL)technology,switched capacitor(SC)technology,and switched inductor-capacitor(SL-SC)technology have been widely applied to optimize and improve dC-dC boost converters,which can effectively enhance voltage gain and reduce device *** address the issue of low output voltage in current renewable energy power generation systems,this study proposes a novel non-isolated cubic high-gain dC-dC converter based on the traditional quadratic dC-dC boost converter by incorporating a SC and a SL-SC ***,the proposed converter’s details are elaborated,including its topology structure,operating mode,voltage gain,device stress,and power ***,a comparative analysis is conducted on the voltage gain and device stress between the proposed converter and other high-gain ***,a closed-loop simulation system is constructed to obtain simulation waveforms of various devices and explore the dynamic ***,an experimental prototype is built,experimental waveforms are obtained,and the experimental dynamic performance and conversion efficiency are *** theoretical analysis’s correctness is verified through simulation and experimental *** proposed converter has advantages such as high voltage gain,low device stress,high conversion efficiency,simple control,and wide input voltage range,achieving a good balance between voltage gain,device stress,and power *** proposed converter is well-suited for renewable energy systems and holds theoretical significance and practical value in renewable energy *** provides an effective solution to the issue of low output voltage in renewable energy power generation systems.

关键词： Cubic dC-dC converter high voltage gain low device stress high efficiency renewable energy

Study of Flow and heat Transfer in an Ejector-driven Swirl Anti-Icing Chamber

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Fluid dynamics & Materials Processing 2024年第5期20卷 989-1014页

作者： Yi Tu Yuan Wu Yu zeng hunan University of Arts and Sciences Hunan Key Laboratory of Distributed Electric Propulsion Vehicle Control TechnologyChangde415000China Liaoning Provincial Key Laboratory of Aircraft Ice Protection AVIC Aerodynamics Research InstituteShenyang110034China School of Aeronautic Science and Engineering Beihang UniversityBeijing100191China

The formation of ice on the leading edge of aircraft engines is a serious issue,as it can have catastrophic *** Swirl Anti-Icing(SAI)system,driven by ejection,circulates hot fluid within a 360°annular chamber to heat the engine inlet lip surface and prevent *** study employs a validated Computational Fluid dynamics(CFd)approach to study the impact of key geometric parameters of this system on flow and heat transfer characteristics within the anti-icing ***,the entropy generation rate and exergy efficiency are analyzed to assess the energy utilization in the *** research findings indicate that,within the considered flow range,reducing the nozzle specific areaφfrom 0.03061 to 0.01083 can enhance the ejection coefficient by over 60.7%.This enhancement increases the air circulating rate,thereby intensifying convective heat transfer within the SAI ***,the reduction inφalso leads to a significant increase in the required bleed air pressure and a higher entropy generation rate,indicating lower exergy *** nozzle angleθnotably affects the distribution of hot and cold spots on the lip surface of the SAI ***θfrom 0°to 20°reduces the maximum temperature difference on the anti-icing chamber surface by 60 K.

关键词： Swirl anti-icing heat transfer exergy efficiency hot and cold spot aircraft engine

A Study on the Performances of Solar Air Collectors having a hemispherical dimple on the Absorber Plate

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Fluid dynamics & Materials Processing 2024年第5期20卷 939-955页

作者： Shuilian Li Fan zeng Xinli Wei School of Architecture and Environmental Engineering Zhengzhou Technical CollegeZhengzhou450121China School of Mechanical and Power Engineering Zhengzhou UniversityZhengzhou450001China

In order to increase the efficiency of solar air collectors,a new variant with a protrusion is proposed in this study,and its performances are analyzed from two points of view,namely,in terms of optics and thermodynamics *** comparing and analyzing the light paths of the protrusion and the dimple,it can be concluded that when sunlight shines on the dimple,it is reflected and absorbed multiple times,whereas for the sunlight shining on the protrusion,there is no secondary reflection or absorption of *** the lighting area and the properties of the surfaces are the same,the absorption rate of the dimple is 10.3 percentage points higher than that of the *** the range of Reynolds number from 3000 to 11000,numerical simulations about the effects of the relative height(e/dh=0.033–0.1)and relative spacing(p/e=4.5–8.5)of protrusions on air heat transfer and flow resistance show that,in terms of comprehensive evaluation coefficient(PF),the best relative height is 0.085,when the relative spacing is 5.A correlation of Nu and f with Re,e/dh and p/e is obtained by linear regression of the results,in order to provide a useful reference for the design and optimization of this kind of solar air collector.

关键词： heat transfer hemispherical protrusion dimple solar air collector correlation

A new class of generalized quasi-variational inequalities with applications to Oseen problems under nonsmooth boundary conditions

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Science China Mathematics 2024年第2期67卷 315-338页

作者： Shengda zeng Akhtar A.Khan Stanislaw Migórski Guangxi Colleges and Universities Key Laboratory of Complex System Optimization and Big data Processing Yulin Normal UniversityYulin 537000China Faculty of Mathematics and Computer Science Jagiellonian University in Krak´owKrak´ow 30348Poland Center for Applied and Computational Mathematics School of Mathematical SciencesRochester Institute of TechnologyRochesterNY 14623USA College of Sciences Beibu Gulf UniversityQinzhou 535000China

In this paper, we study a generalized quasi-variational inequality (GQVI for short) with twomultivalued operators and two bifunctions in a Banach space setting. A coupling of the Tychonov fixedpoint principle and the Katutani-Ky Fan theorem for multivalued maps is employed to prove a new existencetheorem for the GQVI. We also study a nonlinear optimal control problem driven by the GQVI and givesufficient conditions ensuring the existence of an optimal control. Finally, we illustrate the applicability of thetheoretical results in the study of a complicated Oseen problem for non-Newtonian fluids with a nonmonotone andmultivalued slip boundary condition (i.e., a generalized friction constitutive law), a generalized leak boundarycondition, a unilateral contact condition of Signorini’s type and an implicit obstacle effect, in which themultivalued slip boundary condition is described by the generalized Clarke subgradient, and the leak boundarycondition is formulated by the convex subdifferential operator for a convex superpotential.

关键词： generalized quasi-variational inequality existence theorem optimal control Kakutani-Ky Fan theorem Oseen problem non-Newtonian fluid nonmonotone slip boundary condition

Switched-capacitor Based Seven-level Boost Inverter with a Reduced Number of devices

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 381-391页

作者： Weijie Lin Jun zeng Bo Fu Zhixing Yan Junfeng Liu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China WISdRI Engineering&Research Incorporation Limited Wuhan 430074China department of Energy Aalborg UniversityAalborg 9220Denmark School of Automation Science and Engineering South China University of TechnologyGuangzhou 510641China

The conventional multilevel inverters(MLIs)have the disadvantages of numerous devices,incapacity of boost,unbalance for capacitor’s voltage,high complexity for control,and *** by this issue,a seven-level boost inverter(7LBI)based on a switched capacitor is presented for singlephase applications in this *** proposed 7LBI using only seven transistors can achieve seven output levels,1.5 voltage gain,and natural balance of capacitors’voltages without sensors or other auxiliary methods,which illustrates its suitability for the applications of renewable energy *** configuration of topology and operating principles are illustrated in *** natural balance of capacitors and capacitance calculations are deduced as ***,the comparative study is conducted for different types of *** results illustrate the merits of the proposed 7LBI with respect to reduced devices,lower voltage stress,and less power ***,a simulation for the proposed 7LBI with PWM modulation is realized based on the theoretical analysis;an experimental prototype is also implemented,verifying multilevel output,boost ability,natural balance for switched capacitors,and performance of transient response.

关键词： Multilevel inverters voltage gain natural balance renewable energy generation reduced number of elements

Predicting the Mechanical Behavior of a Bioinspired Nanocomposite through Machine Learning

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1299-1313页

作者： Xingzi Yang Wei Gao Xiaodu Wang Xiaowei zeng department of Mechanical Engineering University of Texas at San AntonioSan AntonioTX78249USA department of Mechanical Engineering Texas A&M UniversityCollege StationTX77843USA

The bioinspired nacre or bone structure represents a remarkable example of tough,strong,lightweight,and multifunctional structures in biological materials that can be an inspiration to design bioinspired high-performance *** bioinspired structure consists of hard grains and soft material *** the material interface has a very low volume percentage,its property has the ability to determine the bulk material *** learning technology nowadays is widely used in material science.A machine learning model was utilized to predict the material response based on the material interface properties in a bioinspired *** model was trained on a comprehensive dataset of material response and interface properties,allowing it to make accurate *** results of this study demonstrate the efficiency and high accuracy of the machine learning *** successful application of machine learning into the material property prediction process has the potential to greatly enhance both the efficiency and accuracy of the material design process.

关键词： Bioinspired nanocomposite computational model machine learning finite element material interface

A unified pre-training and adaptation framework for combinatorial optimization on graphs

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Science China Mathematics 2024年第6期67卷 1439-1456页

作者： Ruibin zeng Minglong Lei Lingfeng Niu Lan Cheng School of Computer Science and Technology University of Chinese Academy of SciencesBeijing100049China Faculty of Information Technology Beijing University of TechnologyBeijing100124China School of Economics and Management University of Chinese Academy of SciencesBeijing100190China School of Mathematics and Statistics Central South UniversityChangsha410075China

Combinatorial optimization(CO)on graphs is a classic topic that has been extensively studied across many scientific and industrial ***,solving CO problems on graphs through learning methods has attracted great *** deep learning methods,e.g.,graph neural networks(GNNs),have been used to effectively assist the process of solving ***,current frameworks based on GNNs are mainly designed for certain CO problems,thereby failing to consider their transferable and generalizable abilities among different COs on ***,simply using original graphs to model COs only captures the direct correlations among objects,which does not consider the mathematical logicality and properties of *** this paper,we propose a unified pre-training and adaptation framework for COs on graphs with the help of the maximum satisfiability(Max-SAT)*** first use Max-SAT to bridge different COs on graphs since they can be converted to Max-SAT problems represented by standard formulas and clauses with logical *** we further design a pre-training and domain adaptation framework to extract the transferable and generalizable features so that different COs can benefit from *** the pre-training stage,Max-SAT instances are generated to initialize the parameters of the *** the fine-tuning stage,instances from CO and Max-SAT problems are used for adaptation so that the transferable ability can be further *** experiments on several datasets show that features extracted by our framework exhibit superior transferability and Max-SAT can boost the ability to solve COs on graphs.

关键词： combinatorial optimization graph neural networks domain adaptation maximum satisfiability problem

When smoke meets gut:deciphering the interactions between tobacco smoking and gut microbiota in disease development

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Science China(Life Sciences) 2024年第5期67卷 854-864页

作者： Bo Chen Guangyi zeng Lulu Sun Changtao Jiang Center of Basic Medical Research Institute of Medical Innovation and ResearchPeking University Third HospitalBeijing 100191China department of Physiology and Pathophysiology School of Basic Medical SciencesState Key Laboratory of Vascular Homeostasis and RemodelingPeking UniversityBeijing 100191China Center for Obesity and Metabolic disease Research School of Basic Medical SciencesPeking UniversityBeijing 100191China State Key Laboratory of Women’s Reproductive health and Fertility Promotion Peking UniversityBeijing 100191China department of Endocrinology and Metabolism Peking University Third HospitalBeijing 100191China

Tobacco smoking is a prevalent and detrimental habit practiced worldwide,increasing the risk of various diseases,including chronic obstructive pulmonary disease(COPd),cardiovascular disease,liver disease,and *** previous research has explored the detrimental health effects of tobacco smoking,recent studies suggest that gut microbiota dysbiosis may play a critical role in these *** tobacco smoke components,such as nicotine,are found in the gastrointestinal tract and interact with gut microbiota,leading to lasting impacts on host health and *** review delves into the ways tobacco smoking and its various constituents influence gut microbiota composition and *** also summarize recent advancements in understanding how tobacco smoking-induced gut microbiota dysbiosis affects host ***,this review introduces a novel perspective on how changes in gut microbiota following smoking cessation may contribute to withdrawal syndrome and the degree of health improvements in smokers.

关键词： tobacco smoking gut microbiota dysbiosis nicotine smoking cessation

Nanotechnology-based detection Strategies for hypertension Biomarkers

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Chemical Research in Chinese Universities 2024年第4期40卷 564-576页

作者： WANG Zhichao zeng Yuan WANG Yaling ChEN Chunying henan Institute of Advanced Technology Zhengzhou UniversityZhengzhou450003P.R.China CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety&CAS Center for Excellence in Nanoscience National Center for Nanoscience and Technology of ChinaChinese Academy of Sciences(CAS)Beijing100190P.R.China

hypertension significantly increases the risk of cardiovascular diseases and seriously affects people’s *** incidence of hypertension is rising rapidly in the world and hypertension has become a significant factor influencing the global average life *** diagnosis of hypertension is generally fulfilled by measuring diastolic and systolic blood pressure,but it is insufficient to differentiate essential hypertension from secondary hypertension,so it is crucial to identifying the cause of hypertension by detecting biomarkers in *** clinical practice,five plasma biomarkers are utilized for diagnosing hypertension,and the detection tasks of a large number of cases have raised increasing demands for cost-effective,efficient,speedy,and diverse methods,which makes many traditional diagnostic technologies inadequate for meeting the needs of clinical *** nanomaterial-based detection techniques have frequently attained the qualities of quick reaction,low cost,straightforward operation,high sensitivity,and strong specificity in recent years with the advancement of nanotechnology,so they have great potential for early and rapid *** this review,we will introduce the characteristics and drawbacks of current clinical detection methods for hypertension screening,the principles and advancements of nanotechnology-based detection methods,as well as their potentials for clinical application.

关键词： hypertension Biomarker diagnosis Clinical detection Nanotechnology-based detection