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Size-dependent thermomechanical vibration characteristics of rotating pre-twisted functionally graded shear deformable microbeams

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Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 1015-1032页

作者： Songye JIN Bo ZHANG Wuyuan ZHANG Yuxing WANG Huoming SHEN Jing WANG Juan LIU School of Mechanics and Aerospace Engineering Southwest Jiaotong UniversityChengdu 610031China School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China School of Mechanical and Electrical Engineering Southwest Petroleum UniversityChengdu 610500China

A three-dimensional(3D)thermomechanical vibration model is developed for rotating pre-twisted functionally graded(FG)microbeams according to the refined shear deformation theory(RSDT)and the modified couple stress theory(MCST).The material properties are assumed to follow a power-law distribution along the chordwise *** model introduces one axial stretching variable and four transverse deflection variables including two pure bending components and two pure shear *** complex modal analysis and assumed mode methods are used to solve the governing equations of motion under different boundary conditions(BCs).Several examples are presented to verify the effectiveness of the developed *** coupling the slenderness ratio,gradient index,rotation speed,and size effect with the pre-twisted angle,the effects of these factors on the thermomechanical vibration of the microbeam with different BCs are *** is found that with the increase in the pre-twisted angle,the critical slenderness ratio and gradient index corresponding to the thermal instability of the microbeam increase,while the critical material length scale parameter(MLSP)and rotation speed *** sensitivity of the fundamental frequency to temperature increases with the increasing slenderness ratio and gradient index,and decreases with the other increasing ***,the size effect can suppress the dynamic stiffening effect and enhance the Coriolis ***,the mode transition is quantitatively demonstrated by a modal assurance criterion(MAC).

关键词： thermomechanical vibration rotating pre-twisted functionally graded(FG)microbeam refined shear deformation theory(RSDT) modified couple stress theory(MCST) modal assurance criterion(MAC)

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Vibration Control of A Flexible Marine Riser System Subject to Input Dead Zone and Extraneous Disturbances

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China Ocean Engineering 2024年第2期38卷 271-284页

作者： ZHOU Li WANG Guo-rong WAN Min School of Mechatronic Engineering Southwest Petroleum UniversityChengdu 610500China Energy Equipment Institute Southwest Petroleum UniversityChengdu 610500China National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu 610500China

An observer-based adaptive backstepping boundary control is proposed for vibration control of flexible offshore riser systems with unknown nonlinear input dead zone and uncertain environmental *** control algorithm can update the control law online through real-time data to make the controller adapt to the environment and improve the control ***,based on the adaptive backstepping framework,virtual control laws and Lyapunov functions are designed for each *** direction interference observers are designed to track the timevarying boundary *** this basis,the inverse of the dead zone and linear state transformation are used to compensate for the original system and eliminate the adverse effects of the dead *** addition,the stability of the closed-loop system is proven by Lyapunov stability *** the system states are bounded,and the vibration offset of the riser converges to a small area of the initial ***,four examples of flexible marine risers are simulated in MATLAB to verify the effectiveness of the proposed controller.

关键词： adaptive backstepping control disturbance observer flexible marine riser input dead zone vibration control

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Understanding livelihood vulnerability:a perspective from Western Sichuan’s ethnic rural settings

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Journal of Mountain Science 2024年第2期21卷 380-396页

作者： YU Yongqian JING Zheng WANG Yan QIU Xiaoping YANG Xueting XU Yun School of Geography and Resource Science Sichuan Normal UniversityChengdu 610101China Key Laboratory of land Resources Evaluation and Monitoring in southwest Ministry of EducationSichuan Normal UniversityChengdu 610101China Sichuan County Economic Development Research Center Mianyang Normal UniversityMianyang 621000China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China

To explore the livelihood status and key influencing factors of rural households in the minority areas,we collected flat data from 284 rural households in 32 villages across 12 counties of Western Sichuan from 2021 to *** conducted participatory household survey on the livelihood status of the rural households and try to identify the key factors to influence their livelihood vulnerability using multiple linear *** results showed that:the livelihood situation of the rural households is relatively *** vulnerability varies significantly with the income levels,education levels,and income *** vulnerability of farm households,categorized from low to high livelihood types,follows the sequence:non-agricultural dominant households,non-agricultural households,agricultural dominant households,and pure agricultural *** degree of damage to the natural environment,education costs,loan opportunities,the proportion of agricultural income to annual household income,and the presence of sick people in the household have significant positive effects on the livelihood vulnerability index(LVI)of rural households;while help from relatives and friends,net income per capita,household size,household education,agricultural land area,participation in industrial organizations,number of livestock,purchase of commercial houses,drinking water source,and self-supply of food have significant negative *** on the findings,we believe that local rural households operate in a complex livelihood system and recommend continuous interventions targeting key influences to provide empirical research support for areas facing similar situations.

关键词： Livelihood Vulnerability Rural households Ethnic areas

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Effects of conductive agent type on lithium extraction from salt lake brine with LiFePO_(4) electrodes

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International Journal of Minerals,Metallurgy and Materials 2024年第4期31卷 678-687页

作者： Zhen Zhang Pan Luo Yan Zhang Yuhan Wang Li Liao Bo Yu Mingshan Wang Junchen Chen Bingshu Guo Xing Li School of New Energy and Materials Southwest Petroleum UniversityChengdu 610500China Energy Storage Research Institute Southwest Petroleum UniversityChengdu 610500China

Electrochemical lithium extraction from salt lakes is an effective strategy for obtaining lithium at a low ***,the elevated Mg:Li ratio and the presence of numerous coexisting ions in salt lake brines give rise to challenges,such as prolonged lithium extraction periods,diminished lithium extraction efficiency,and considerable environmental *** this work,Li FePO4(LFP)served as the electrode material for electrochemical lithium *** conductive network in the LFP electrode was optimized by adjusting the type of conductive *** approach resulted in high lithium extraction efficiency and extended cycle *** the single conductive agent of acetylene black(AB)or multiwalled carbon nanotubes(MWCNTs)was replaced with the mixed conductive agent of AB/MWCNTs,the average diffusion coefficient of Li+in the electrode increased from 2.35×10^(-9)or 1.77×10^(-9)to 4.21×10^(-9)cm^(2)·s^(-1).At the current density of 20 mA·g^(-1),the average lithium extraction capacity per gram of LFP electrode increased from 30.36 mg with the single conductive agent(AB)to 35.62 mg with the mixed conductive agent(AB/MWCNTs).When the mixed conductive agent was used,the capacity retention of the electrode after 30 cycles reached 82.9%,which was considerably higher than the capacity retention of 65.8%obtained when the single AB was ***,the electrode with mixed conductive agent of AB/MWCNTs provided good cycling *** the conductive agent content decreased or the loading capacity increased,the electrode containing the mixed conductive agent continued to show excellent electrochemical ***,a self-designed,highly efficient,continuous lithium extraction device was *** electrode utilizing the AB/MWCNT mixed conductive agent maintained excellent adsorption capacity and cycling performance in this *** work provides a new perspective for the electrochemical extraction of lithium using LFP electrodes.

关键词： salt lake brine lithium extraction electrochemical lithium extraction conductive agent extraction efficiency adsorption capacity

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Leakage and diffusion characteristics of underground hydrogen pipeline

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Petroleum 2024年第2期10卷 319-325页

作者： Wenkang Zhang Guanghui Zhao School of Mechatronic Engineering Southwest Petroleum University

Soil corrosion and hydrogen embrittlement are the main factors of hydrogen pipeline failure. The gas escapes, diffuses and accumulates in the soil and enters the atmosphere when leak occurs. The mechanism of gas diffusion in buried pipelines is very complicated. Mastering the evolution law of hydrogen leakage diffusion is conducive to quickly locating the leakage point and reducing the loss. The leakage model of the underground hydrogen pipeline is established in this paper. The effect of leakage hole, soil type, pipeline pressure, pipeline diameter on hydrogen leakage diffusion were investigated. The results show that when the hydrogen pipeline leaks, the hydrogen concentration increases with the increase of leakage time, showing a symmetrical distribution trend. With the pipeline pressure increase, hydrogen leakage speed is accelerated, and longitudinal diffusion gradually becomes the dominant direction. As the leakage diameter increases, hydrogen leakage per unit of time increases sharply. Hydrogen diffuses more easily in sandy soil, and its diffusion speed, concentration, and range are higher than that in clay soil. The research content provides a reference and basis for the detection and evaluation of buried hydrogen pipeline leakage.

关键词： Buried pipeline Hydrogen leakage Diffusion characteristics Numerical simulation

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Electromagnetic anisotropic homogeneous model for eddy-current field in single-phase wound core

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High Voltage 2024年第1期9卷 172-181页

作者： Lijun Zhou Woyang Li Yingyi Xia Jiawei Chen Chenqingyu Zhang Xiaohu Cai Lei Guo Dongyang Wang School of Electrical Engineering Southwest Jiaotong UniversityChengduChina

The analysis of the eddy-current field in the wound core widely used in the field of transformer energy conservation is taken as the *** the homogenisation idea to consider the unique geometry of the wound core and features of its equivalent multi-stage circular cross-section magnetic boundary,a homogeneous model consisting of a columnar material with continuous homogeneous electromagnetic anisotropy is established by deriving the Maxwell equations of the magnetic quasi-static field in the columnar coordinate ***,a homogeneous fine element model for the eddycurrent field in the wound core is established and the accuracy of the model has been verified by the test *** result shows that the homogeneous model can be effectively used for the analysis of the eddy-current field in the wound core,and the error of calculating the eddy-current loss under different excitation conditions is less than 6%under the premise of extremely saving the engineering calculation cost,which will help improve the operational performance of the wound core and contribute to the energysaving goal of the high-voltage equipment.

关键词： anisotropic coordinate excitation

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Voltage rise rate-related generalised probabilistic lifetime model of turn-to-turn insulation in inverter-fed motors

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High Voltage 2024年第1期9卷 46-55页

作者： Yan Yang Xueyang Bai Yuxing Lei Kai Liu Guangning Wu School of Electrical Engineering Southwest Jiaotong UniversityChengduChina

The lifetime model of turn-to-turn insulation in inverter-fed motors is studied.A lifetime model has been built by considering the effect of inverter-generated high voltage rise rate(dv/dt up to 20 V/ns).This model is followed by the generalised probabilistic model,in which the lifetime is proportional to the nth power of the voltage rise ***,by investigating the effect of voltage rise rate on the partial discharge characteristics,it is found that the effect of voltage rise rate on the charge transport process in a voltage cycle is similar to that of the voltage *** enhanced partial discharge activity and induced charges are responsible for accelerated ageing and thus determine the final lifetime of turn-to-turn *** this case,the generalised probabilistic electric lifetime model is applicable to the voltage rise rate as well as the voltage amplitude.

关键词： lifetime inverter insulation

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Oral delivery of ferroptosis inducers for effective treatment of hepatic fibrosis

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Nano Research 2024年第8期17卷 7621-7630页

作者： Yinglan Yu Shunlong Zhang Yongfeng Xu Hao Shao Lei Luo College of Pharmaceutical Sciences Southwest UniversityChongqing 400715China

Liver fibrosis is characterized by the excessive accumulation of extracellular matrix(ECM),which is primarily produced by activated hepatic stellate cells(HSCs).However,effective therapies for hepatic fibrosis are currently *** is a promising anti-fibrotic drug candidate,but its clinical application is hindered by limited ***,we present a novel oral delivery platform that enhances the HSCs uptake of artesunate and induces potent *** platform is vitamin Adecorated nanoparticles encapsulated with *** multifunctional ligand vitamin A interacts with retinol-binding proteins that are highly expressed on the intestinal epithelium to promote transcytosis,highly expressed on the surface of HSCs but lowly expressed in normal *** oral administration,this oral delivery platform enhances transepithelial transport in the intestine,improves drug accumulation in the liver,and continuously increases HSCs uptake of *** drug release in HSCs,artesunate depletes glutathione peroxidase 4 and glutathione,effectively initiating *** vivo experiments demonstrate that this strategy induces pronounced ferroptosis,efficiently relieving liver *** work provides a proof-ofconcept demonstration that an oral delivery strategy for ferroptosis inducers may be beneficial for liver fibrosis treatment.

关键词： liver fibrosis hepatic stellate cells oral delivery intestinal epithelium ferroptosis

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Neural network study of the nuclear ground-state spin distribution within a random interaction ensemble

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Nuclear Science and Techniques 2024年第3期35卷 216-227页

作者： Deng Liu Alam Noor A Zhen-Zhen Qin Yang Lei School of Mathematics and Physics Southwest University of Science and TechnologyMianyang 621010China School of Nuclear Science and Technology Southwest University of Science and TechnologyMianyang 621010China

The distribution of the nuclear ground-state spin in a two-body random ensemble(TBRE)was studied using a general classification neural network(NN)model with two-body interaction matrix elements as input features and the corresponding ground-state spins as labels or output *** quantum many-body system problem exceeds the capability of our optimized NNs in terms of accurately predicting the ground-state spin of each sample within the ***,our NN model effectively captured the statistical properties of the ground-state spin because it learned the empirical regularity of the ground-state spin distribution in TBRE,as discovered by physicists.

关键词： Neural network Two-body random ensemble Spin distribution of nuclear ground state

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From Teacher-Education university to Comprehensive university:Case Studies of East China normal university,southwest university and Yanbian university

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Frontiers of Education in China 2010年第4期5卷 507-530页

作者： LI Mei Institute of Higher Education East China Normal UniversityShanghai 200062China

Three different“logics”—that of the internal strategies of the institutions,the economic pressures of the socialist market economy and the political policies of the state drive the development of a *** dynamic interaction and coexistence of the three logics has determined the transformation models of teacher-education or normal universities in *** paper aims at describing and analyzing both the process and the forces that led to these transformations by taking East China normal university(ECNU),southwest university(SWU)and Yanbian university(YBU)as *** on government and market resources has put these universities into a dilemma:On the one hand,they wanted to retain their original features so as to preserve their leading position in the“teacher education”market,and on the other,they needed to merge,expand,restructure and enhance their quality as they pursued overall *** case analyses show that the teacher-education university’s need for self-development,which is the internal determinant,plays a critical role in its *** the same time,the socioeconomic environment and national policies influence the institution while it displays considerable capacity for self-adjustment.

关键词： normal/teacher-education universities comprehensiveness East China normal university(ECNU) southwest university(SWU) Yanbian university(YBU)

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