检索结果-南通市图书馆

融合多策略改进的灰狼优化算法及其在汽轮机转子应力监测上的应用

在线全文

学校读者我要写书评

暂无评论

汽轮机技术 2024年第2期66卷 138-144页

作者：丁先李汪繁徐佳敏臧剑南吴何来上海发电设备成套设计研究院有限责任公司上海200240

针对灰狼优化算法求解精度低和易陷入局部最优的缺陷,提出一种融合多策略改进的灰狼优化算法(improved grey wolf optimization algorithm,IGWO)。首先采用混沌映射规则生成初始解,以增强初始种群的均匀性和遍历性;其次加入狼群交叉变... 详细信息

针对灰狼优化算法求解精度低和易陷入局部最优的缺陷,提出一种融合多策略改进的灰狼优化算法(improved grey wolf optimization algorithm,IGWO)。首先采用混沌映射规则生成初始解,以增强初始种群的均匀性和遍历性;其次加入狼群交叉变异过程,以增加种群的多样性,避免陷入局部最优;最后引入动态惯性权重对灰狼位置进行更新,加快迭代过程的收敛。将IGWO与其它相似算法进行实验对比分析,结果表明:IGWO在6个标准函数的测试中优化性能表现最优,验证了其求解精度更高,泛化能力更强;将IGWO应用到某300MW级火电机组的汽轮机转子应力监测问题上,采用IGWO优化支持向量回归(support vector regression,SVR)建立的预测模型相对误差处于[-1.33%,1.88%],平均相对误差为0.64%;相较于其它预测方法,IGWO-SVR具有较高的求解精度和稳定性,验证了改进措施可有效提高IGWO的寻优性能,相关研究结论可为GWO的改进和汽轮机转子应力监测提供参考。

关键词：灰狼优化算法多策略混沌映射交叉变异动态惯性权重应力监测

Prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 192-212页

作者： fan wang Xiuli Du Pengfei li Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing100124China

This study focuses on the analytical prediction of subsurface settlement induced by shield tunnelling in sandy cobble stratum considering the volumetric deformation modes of the soil above the tunnel crown.A series of numerical analyses is performed to examine the effects of cover depth ratio(C/D),tunnel volume loss rate(h t)and volumetric block proportion(VBP)on the characteristics of subsurface settle-ment trough and soil volume *** the ground loss variation with depth,three modes are deduced from the volumetric deformation responses of the soil above the tunnel ***,analytical solutions to predict subsurface settlement for each mode are presented using stochastic medium *** influences of C/D,h t and VBP on the key parameters(i.e.B and N)in the analytical expressions are discussed to determine the fitting formulae of B and ***,the proposed analytical solutions are validated by the comparisons with the results of model test and numerical *** show that the fitting formulae provide a convenient and reliable way to evaluate the key ***,the analytical solutions are reasonable and available in predicting the subsurface settlement induced by shield tunnelling in sandy cobble stratum.

关键词： Shield tunnelling Sandy cobble stratum Subsurface settlement Volumetric deformation mode Stochastic medium theory

Experimental and numerical study regarding H-steel all-bolted connection steel frame with composite wall boards

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2024年第2期23卷 427-443页

作者： fan Min Guo Hongchao li Shen wang Zhenshan wang Huaqiang School of Civil Engineering and Architecture Xi’an University of TechnologyXi’an 710048China State Key Laboratory Base of Eco-Hydraulic Engineering in Arid Area Xi’an University of TechnologyXi’an 710048China

H-steel all-bolted connection steel frame structures with heat preservation and decoration composite wall boards were investigated and the seismic performances of three scaled specimens were *** failure modes,hysteresis curves,bearing capacity,ductility,energy dissipation capacity,stiffness degradation and strain distribution were *** calculation method of structural theoretical internal force was *** results showed that the overall structural seismic performance was better,and the structural ductility met the demands of elastic-plastic inter-story drift angle for seismic *** H-steel weak-axis connection structure obtained better energy dissipation capacity,and its bearing capacity and stiffness were slightly different from the strong-axis *** heat preservation and decoration performance of composite wallboard and the all-bolted connection of the steel frame realized prefabrication during the whole construction *** plastic hinge of the steel beam can be moved outwards because of the L-angles,which effectively avoids stress concentration in joint areas and expands the plastic hinge *** errors between the theoretical structural capacity calculated by the plastic analysis method and the test results were within 2.44%.In addition,structural failure mechanisms and bearing capacities were verified by the finite element(FE)analysis,and the effects of the main parameters on the structures were *** FE verification results were the same as in the *** research results provide theoretical support and technical guidance for the application of thermal insulation and decorative composite wall panels in H-shaped steel all-bolted steel frames.

关键词： composite wall boards all-bolted steel frame H-steel low-cyclic loading failure modes

Semisymmetric Graphs of Order 2p^(3)with Valency p^(2)

在线全文

学校读者我要写书评

暂无评论

Algebra Colloquium 2024年第2期31卷 199-208页

作者： li wang Songtao Guo Genghua fan School of Mathematics and Information Science Henan Polytechnic University JiaozuoHenan 454000China School of Mathematics and Statistics Henan University of Science and Technology LuoyangHenan 471023China 不详

A simple undirected regular graph is said to be semisymmetric if it is edge-transitive but not *** a semisymmetric graphΓof order 2p^(3),p a prime,it is well known thatΓis bipartite with two biparts having equal *** complete classification of such graphs has been given for the full automorphism group Aut(Γ)acting unfaithfully on at least one bipart ofΓ,which shows that there is only one infinite family of such graphs with valency p^(2).The graphs of this kind have been determined when Aut(Γ)acts faithfully and primitively on at least one bipart ofΓ,and thus there is only one remaining case for classifying such graphs of valency p^(2),Aut(Γ)acting faithfully and imprimitively on both biparts ofΓ,which is dealt with in this *** a result,there is only one infinite family of semisymmetric graphs of order 2p^(3)with valency p^(2).

关键词： semisymmetric graph semitransitive graph bi-coset graph

Elevated radial arterial augmentation index in hypertensive patients with diastolic dysfunction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Geriatric Cardiology 2008年第2期5卷 67-73页

作者： Qiang Zeng Xiaonan Sun li fan Xinming wang Ping Ye The Second Department of Geriatrics Cardiology Chinese PLA General HospitalBeijing 100853China The Second Department of Geriatrics CardiologyChinese PLA General HospitalBeijing 100853China The Second Department of Geriatrics CardiologyChinese PLA General HospitalBeijing 100853China The Second Department of Geriatrics CardiologyChinese PLA General HospitalBeijing 100853China The Second Department of Geriatrics CardiologyChinese PLA General HospitalBeijing 100853China

Objective To investigate the correlation between augmentation index (AI) of the radial artery and diastolic heart function in patients with hypertension. Methods Echocardiographs were obtained for 305 patients with hypertension. AI, pulse wave velocity (PWV) of peripheral arteries and serum pro-brain natriuretic peptide (proBNP) levels were determined. Correlations and receiver operating characteristic (ROC) curves were drawn between AI values and impaired diastolic function. Results AI levels were significantly increased in patients with impaired diastolic function diagnosed by ultrasound. Assessment of diastolic heart function based on proBNP levels revealed that AI and aortic pulse wave velocity were significantly elevated in patients with impaired diastolic function. The operating curve indicated that AI may be a more accurate and efficient index for the evaluation of impaired diastolic function compared to PWV. Correlation analysis also showed that proBNP levels had altered in parallel with changes in AI and PWV. After adjusting for various factors including age, gender, blood pressure and blood lipid, a positive correlation was observed between proBNP and AI with a correlation coefficient of 0.3697 (P=0.003). However, no correlation between proBNP and aortic PWV was seen after adjustment. Conclusions Changes in radial AI levels may reflect parallel changes in diastolic cardiac function in patients with hypertension, suggesting that AI may be utilized as a non-invasive clinical indicator of diastolic heart function.

关键词： augmentation index diastolic heart failure hypertension pro BNP pulse wave velocity

Ternary layered boride MoAlB:A novel thermo-regulation microwave absorbing ceramic material

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2024年第5期13卷 699-710页

作者： Zhangjue wang fan Zhang Nannan wang Wei li Yongqiang Chen Hailong wang Rui Zhang Yanqiu Zhu Bingbing fan School of Material Science and Engineering Zhengzhou UniversityZhengzhou 450001China Henan Academy of Sciences Zhengzhou 450046China State Key Laboratory of Featured Metal Materials and life Cycle Safety for Composite Structures MOE Key Laboratory of New Processing Technology for Nonferrous Metals MaterialsSchool of ResourcesEnvironment and MaterialsGuangxi UniversityNanning 530004China Department of Materials and Earth Sciences Technical University of DarmstadtDarmstadt 64287Germany School of Material Science and Engineering Luoyang Institute of Science and TechnologyLuoyang 471023China Department of Engineering Faculty of EnvironmentScience and EconomyUniversity of ExeterExeter EX44QFUK

In the context of the fifth-generation(5G)smart era,the demand for electromagnetic wave(EMW)-absorbing materials has become increasingly prominent,so it is necessary to explore promising candidate *** work focuses on the exploration of the material absorbing properties of a MoAlB MAB(MAB represents a promising group of alternatives,where M stands for a transition metal,A typically denotes Al,and B is boron)phase ***,the first-principles calculations were performed to reveal the unique crystal and layered structure of the MoAlB ceramics and to predict their potential for use as an EMW absorption ***,a series of MoAlB ceramics were synthesized at temperatures ranging from 800 to 1300℃,and the influence of temperature on the phase compositions and microstructures of the obtained MoAlB ceramics was characterized and ***,the practical EMW absorption performance of the prepared MoAlB ceramics was evaluated via a combination of experiments and radar cross-sectional *** MoAlB sample synthesized at 900℃ exhibits superior EMW absorption performance,achieving an impressive minimum reflection loss(RL)of−50.33 *** unique layered structure and good electrical conductivity of the MoAlB samples are the main reasons for their enhanced wave absorption performance,which provides interfacial polarization and multiple dielectric loss ***,this study not only contributes to the understanding of the preparation of MoAlB materials but also provides potential guidance for their utilization in the realm of electromagnetic wave absorption.

关键词： MoAlB electronic band structure electromagnetic wave(EMW)absorption layered ternary boride density of states

Investigation of electrostatically tunable adhesion and instability of flying head slider

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Friction 2024年第3期12卷 462-473页

作者： fan ZHANG Yu wang Yueqiang HU Mingquan ZHANG Baotong li School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China National Engineering Research Center for High Efficiency Grinding College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082China

The interfacial adhesion between microstructures is inevitable in a micro-electro-mechanical system(e.g.,hard disk drive(HDD)),which may lead to complicated microtribodynamics *** research has investigated the effect of surface potential on the interfacial adhesion and microtribodynamics of the head–disk interface(HDI)in an HDD.A dynamic continuum surface force model,where the electrowetting is considered,is proposed to evaluate the interfacial interaction,and then employed into a two-degree-of-freedom(2DOF)model to theoretically analyze the potential influence mechanism on the *** results confirm that the elimination of potential can effectively repress the adhesion retention,which is further proved by the measured slider response with a laser Doppler vibrometer(LDV).Moreover,the effect of the potential on the adhesion-induced instability is also analyzed through the phase *** tells that the critical stable flying height can be lowered with the elimination of potential.

关键词： electric field(EF) retention instability adhesion

Advances in friction of aluminium alloy deep drawing

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Friction 2024年第3期12卷 396-427页

作者： Yiren GAO Hongxia li Danyang ZHAO Minjie wang Xiaobo fan School of Mechanical Engineering Dalian University of TechnologyDalian 116023China

Broad use of lightweight aluminium alloy parts in automobile manufacturing,aerospace,electronic communication,and rail transit is mainly formed through deep drawing *** drawing friction is a key boundary condition for controlling the forming quality of aluminium alloy ***,due to the oxidation and adhesion tendency of aluminium alloys,the tribological situations of aluminium alloy deep drawing(AADD)system is more complicated than those of traditional deep drawing of steel ***,the study of AADD friction is essential for manufacturing high-performance aluminium alloy ***,aiming to provide a valuable reference for researchers in related fields,a comprehensive review of AADD friction is provided,including friction mechanism,influencing factors,friction measurement,friction model,friction simulation,and lubrication-free friction ***,a brief conclusion and several current challenges were discussed.

关键词： aluminium alloy deep drawing(AADD) influencing factors friction measurement friction model friction control

A multi-scale framework for life reduction assessment of turbine blade caused by microstructural degradation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第1期37卷 186-200页

作者： Xiaoguang YANG Menglei wang Duoqi SHI Zhenlei li Yongsheng fan School of Energy and Power Engineering Beihang UniversityBeijing 102206China Research Institute of Aero-Engine Beihang UniversityBeijing 102206China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing 102206China

The prolonged thermal exposure with centrifugal load results in microstructural degradation,which ultimately leads to a reduction in the fatigue and creep resistance of the turbine *** present work proposes a multi-scale framework to estimate the life reduction of turbine blades,which combines a microstructural degradation model,a two-phase constitutive model,and a microstructure-dependent fatigue and creep life reduction *** framework with multi-scale models is validated by a Single Crystal(SC)Ni-based superalloy at the microstructural length-scale and is then applied to calculate the microstructural degradation and the fatigue and creep life reduction of turbine blades under two specific service *** simulation results and quantitative analysis show that the microstructural degradation and fatigue and creep life reduction of the turbine blade are heavily influenced by the variations in the proportion of the intermediate state,namely,the maximum rotor speed status,in the two specific service *** intermediate state accelerates the microstructural degradation and leads to a reduction of the life,especially the effective fatigue life reserve due to the higher temperature and rotational speed than that of the 93%maximum rotor speed status marked as the reference *** proposed multi-scale framework provides a capable approach to analyze the reduction of the fatigue and creep life for turbine blade induced by microstructural degradation,which can assist to determine a reasonable Time Between Overhaul(TBO)of the engine.

关键词： Creep Fatigue life reduction Microstructural degradation Multi-scale modeling Turbine blades