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动力特性 6

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Effects of elastic support on the dynamic behaviors of the wind turbine drive train

Shuaishuai WANG, Caichao ZHU, Chaosheng SONG, Huali HAN

《机械工程前沿(英文)》 2017年 第12卷 第3期   页码 348-356 doi: 10.1007/s11465-017-0420-7

摘要:

The reliability and service life of wind turbines are influenced by the complex loading applied on the hub, especially amidst a poor external wind environment. A three-point elastic support, which includes the main bearing and two torque arms, was considered in this study. Based on the flexibilities of the planet carrier and the housing, a coupled dynamic model was developed for a wind turbine drive train. Then, the dynamic behaviors of the drive train for different elastic support parameters were computed and analyzed. Frequency response functions were used to examine how different elastic support parameters influence the dynamic behaviors of the drive train. Results showed that the elastic support parameters considerably influenced the dynamic behaviors of the wind turbine drive train. A large support stiffness of the torque arms decreased the dynamic response of the planet carrier and the main bearing, whereas a large support stiffness of the main bearing decreased the dynamic response of planet carrier while increasing that of the main bearing. The findings of this study provide the foundation for optimizing the elastic support stiffness of the wind turbine drive train.

关键词: wind turbine drive train     elastic support     dynamic behavior     frequency response function    

Influence mechanism of dynamic and static liquid bridge forces on particle deposition behaviors in solar

Xueqing LIU, Xiaodong ZHAO, Luyi LU, Jianlan LI

《能源前沿(英文)》 2021年 第15卷 第2期   页码 499-512 doi: 10.1007/s11708-021-0742-3

摘要: Solar energy is one of the most promising forms of renewable energy for solving the energy crisis and environmental problems. Dust deposition on photovoltaic mirrors has a serious negative impact on the photoelectric conversion efficiency of solar power stations. In this paper, the influence mechanism of the dynamic and static liquid bridge forces on particle deposition behaviors on solar photovoltaic mirrors is investigated. In addition, the expression and physical meaning of the particle critical separation velocity are proposed. The research results show that the static liquid bridge force can be the primary deposition force causing dust particles to adhere to photovoltaic mirrors. However, the dynamic liquid bridge force can act as a resistance force for the particle motion process and even make dust particles roll along and finally stay on the mirror. The contact force is the primary separation force that causes dust particles to flow away from the mirror. Whether dust particles adhere to the mirror depends on the relative size of the deposition and separating forces. The particle critical separation velocity describes the relative size of the collision-rebound effect and mirror adhesion effect and is expressed in Eq. (16). These research findings can provide theoretical guidance for mirror cleaning methods in the operation process of photovoltaic mirrors.

关键词: dust deposition     discrete element method (DEM)     photovoltaic mirrors     solar energy    

Dynamic performance of submerged floating tunnel with different mooring styles subjected to anchor cable

《结构与土木工程前沿(英文)》 doi: 10.1007/s11709-023-0932-7

摘要: Submerged floating tunnels (SFTs) are novel structures for transportation across long- and deep-strait regions. Owing to severe wave and current excitation as well as the effects of underwater structures and corrosion, the risk of local anchor cable failure is high, which can result in the progressive failure of the entire structure. In this study, experimental and numerical investigations are conducted to analyze the dynamic behavior of an SFT with different mooring styles under local cable failure. A custom-designed cable failure device and the birth-and-death element method are used to simulate cable failure (i.e., progressive failure) via experiments and numerical simulation, respectively. A physical-scale segmental model of an SFT with different mooring styles under anchor cable failure is developed in this study. A segmental and entire-length mathematical model is developed using the ANSYS program to perform the numerical simulation. The results of the segmental numerical and experimental models indicate good agreement. The dynamic response of an SFT with different mooring styles under cable failure is comprehensively investigated by investigating the effects of key parameters (wave period, buoyant weight ratio, and cable failure mechanism). Moreover, the progressive failure of the SFT under cable failure is investigated via a segment model test and a numerical simulation of its entire length. The present study can serve as a reference for the safer designs of the SFT mooring style.

关键词: dynamic behaviors     submerged floating tunnel     cable failure     mooring style     progressive failure    

Flocculation behaviors of a novel papermaking sludge-based flocculant in practical printing and dyeing

《环境科学与工程前沿(英文)》 2021年 第15卷 第5期 doi: 10.1007/s11783-021-1390-x

摘要:

•PSBF performed better than PAC and PAM in CODCr removals.

关键词: Practical wastewater treatment     Commercial coagulant/flocculant     Secondary coagulation-flocculation process     Chemical oxygen demand     Coagulation-flocculation mechanism    

Thermal defluorination behaviors of PFOS, PFOA and PFBS during regeneration of activated carbon by molten

《环境科学与工程前沿(英文)》 2022年 第16卷 第8期 doi: 10.1007/s11783-022-1524-9

摘要:

• New method of mineralizing PFCs was proposed.

关键词: PFCs     Molten sodium hydroxide     Thermal degradation     Activated carbon regeneration    

CFD simulation of jet behaviors in a binary gas-solid fluidized bed: comparisons with experiments

Pei PEI, Guiying WU, Bangting YU, Kai ZHANG, Jianchun JIANG, Dongsheng WEN,

《化学科学与工程前沿(英文)》 2010年 第4卷 第3期   页码 242-249 doi: 10.1007/s11705-009-0277-3

摘要: Based on the experimental observation of the fluidization characteristics of solid mixtures (resin and rapeseed) with different densities and sizes, the jet behaviours of the binary system are simulated in a two-dimensional jetting fluidized bed 0.30 m in width and 2.00 m in height. A simple mathematical model, by introducing two additional force terms in both gas and particle phase momentum equations of Gidaspow’s inviscid two-fluid model, is used to explore the effects of jet gas velocity and mixture combination on the jet penetration depth in the fluidized bed with a binary system. Experimental results show that there is a fluidization velocity interval (-) for the resin-on-rapeseed (flotsam-on-jetsam) segregated bed. The simulated jet penetration depth increases with the increase of jet gas velocity and the volume fraction of the flotsam (resin), which is in fair agreement with experimental data. The above findings show that the hydrodynamic model of Brandani and Zhang (2006), by introducing the average physical properties from Goossens et al.(1971), can be used to predict the jet behaviors of a well-mixing binary system.

关键词: mathematical     two-dimensional     flotsam-on-jetsam     fluidization velocity     physical    

高速润滑脂的弹流拖动特性

杨伯原,郑培斌,苏冰,吴勇军,邓四二

《中国工程科学》 2002年 第4卷 第4期   页码 75-78

摘要:

弹流拖动特性是润滑剂的重要性能,它对滚动轴承的 动态性能有着很大的影响。阐述了用自行设计的高速润滑脂弹流拖动力试验台在充分供脂条件下对国产7007和7018润滑脂进行的拖动力测试以及试验数据的处理,并提出了可供工程上使用的这两种润滑脂的弹流拖动系数计算公式。

关键词: 弹流润滑     拖动力试验     拖动特性    

Analysis of molten metal spreading and solidification behaviors utilizing moving particle full-implicit

《能源前沿(英文)》 2021年 第15卷 第4期   页码 959-973 doi: 10.1007/s11708-021-0753-0

摘要: To retrieve the fuel debris in Fukushima Daiichi Nuclear Power Plants (1F), it is essential to infer the fuel debris distribution. In particular, the molten metal spreading behavior is one of the vital phenomena in nuclear severe accidents because it determines the initial condition for further accident scenarios such as molten core concrete interaction (MCCI). In this study, the fundamental molten metal spreading experiments were performed with different outlet diameters and sample amounts to investigate the effect of the outlet for spreading-solidification behavior. In the numerical analysis, the moving particle full-implicit method (MPFI), which is one of the particle methods, was applied to simulate the spreading experiments. In the MPFI framework, the melting-solidification model including heat transfer, radiation heat loss, phase change, and solid fraction-dependent viscosity was developed and implemented. In addition, the difference in the spreading and solidification behavior due to the outlet diameters was reproduced in the calculation. The simulation results reveal the detailed solidification procedure during the molten metal spreading. It is found that the viscosity change and the solid fraction change during the spreading are key factors for the free surface condition and solidified materials. Overall, it is suggested that the MPFI method has the potential to simulate the actual nuclear melt-down phenomena in the future.

关键词: molten metal spreading     solidification     particle method     severe accident     fuel debris     decommissioning    

Cannabidiol prevents depressive-like behaviors through the modulation of neural stem cell differentiation

《医学前沿(英文)》 2022年 第16卷 第2期   页码 227-239 doi: 10.1007/s11684-021-0896-8

摘要: Chronic stress impairs radial neural stem cell (rNSC) differentiation and adult hippocampal neurogenesis (AHN), whereas promoting AHN can increase stress resilience against depression. Therefore, investigating the mechanism of neural differentiation and AHN is of great importance for developing antidepressant drugs. The nonpsychoactive phytocannabinoid cannabidiol (CBD) has been shown to be effective against depression. However, whether CBD can modulate rNSC differentiation and hippocampal neurogenesis is unknown. Here, by using the chronic restraint stress (CRS) mouse model, we showed that hippocampal rNSCs mostly differentiated into astrocytes under stress conditions. Moreover, transcriptome analysis revealed that the FoxO signaling pathway was involved in the regulation of this process. The administration of CBD rescued depressive-like symptoms in CRS mice and prevented rNSCs overactivation and differentiation into astrocyte, which was partly mediated by the modulation of the FoxO signaling pathway. These results revealed a previously unknown neural mechanism for neural differentiation and AHN in depression and provided mechanistic insights into the antidepressive effects of CBD.

关键词: cannabidiol     depression     radial neural stem cells     neurogenesis    

Controlling microbiological interfacial behaviors of hydrophobic organic compounds by surfactants in

ZHANG Dong,ZHU Lizhong

《环境科学与工程前沿(英文)》 2014年 第8卷 第3期   页码 305-315 doi: 10.1007/s11783-014-0647-z

摘要: Bioremediation of hydrophobic organic compounds (HOCs) contaminated soils involves several physicochemical and microbiological interfacial processes among the soil-water-microorganism interfaces. The participation of surfactants facilitates the mass transport of HOCs in both the physicochemical and microbiological interfaces by reducing the interfacial tension. The effects and underlying mechanisms of surfactants on the physicochemical desorption of soil-sorbed HOCs have been widely studied. This paper reviewed the progress made in understanding the effects of surfactant on microbiological interfacial transport of HOCs and the underlying mechanisms, which is vital for a better understanding and control of the mass transfer of HOCs in the biodegradation process. In summary, surfactants affect the microbiological interfacial behaviors of HOCs during three consecutive processes: the soil solution-microorganism sorption, the transmembrane process, and the intracellular metabolism. Surfactant could promote cell sorption of HOCs depending on the compatibility of surfactant hydrophile hydrophilic balance (HLB) with cell surface properties; while the dose ratio between surfactant and biologic mass (membrane lipids) determined the transmembrane processes. Although surfactants cannot easily directly affect the intracellular enzymatic metabolism of HOCs due to the steric hindrace, the presence of surfactants can indirectly enhanced the metabolism by increasing the substrate concentrations.

关键词: biodegradation     sorption     transmembrane transport     microbiological interfaces     surfactants    

Endosulfan residues and farmers’ replacement behaviors of endosulfan in the north-west inland cotton

《环境科学与工程前沿(英文)》 2023年 第18卷 第4期 doi: 10.1007/s11783-024-1803-8

摘要:

● The situation of endosulfan residues in cotton fields were assessed.

关键词: Cotton fields     Endosulfan residues     Farmers     KAP survey     Replacement behaviours    

Creep and recovery behaviors of magnetorheological elastomers

Weihua LI, Yang ZHOU, Tongfei TIAN, Gursel ALICI,

《机械工程前沿(英文)》 2010年 第5卷 第3期   页码 341-346 doi: 10.1007/s11465-010-0096-8

摘要: This paper presents experimental and modeling study of creep and recovery behaviors of magneto-rheological elastomers (MREs) under constant stresses. Experimental study was accomplished using a rheometer with parallel-plate geometry. Under constant stresses ranging from a small value to a large one, the resultant strains were recorded. The experimental results demonstrated that MREs behave as linear visocleastic properties. The effects of the magnetic field and stress on MRE creep behaviors were discussed. Moreover, a four-parameter viscoelastic model was developed to describe MRE creep behaviors. The comparison between the experimental results and the modeling predictions indicates that the model can predict MRE creep behaviors very well.

关键词: magneto-rheological elastomers (MREs)     creep     recovery     linear viscoelastic model    

Vibratory behaviors of Jeffcott system on cylindrical roller bearings

Hao WU, Jianwen WANG, Qi AN

《机械工程前沿(英文)》 2009年 第4卷 第3期   页码 305-309 doi: 10.1007/s11465-009-0036-7

摘要: A Jeffcott rotor system of cylindrical roller bearings is studied in detail. Its critical speed is calculated by a new calculation method with roller bearing stiffness and damping. The influences of bearing parameters, such as the roller length, rotor mass, distance between the bearings and the kinematics viscosity of oil on the system critical speed are numerically studied, and the influences of an oil film and damping on the critical speed are also studied. Regular curves of the relationship between the geometric parameters and the system critical speed are obtained. The results show that with increasing roller length and radial load, the critical speed increases; and with increasing rotor mass and the distance between the bearings and the kinematics viscosity, the critical speed decreases. This means that an oil film will decrease the critical rotational speed of the rotor system.

关键词: roller bearing     bearing-rotor system     design value     critical rotational speed    

Time- and temperature-dependence of compressive and tensile behaviors of polypropylene fiber-reinforced

《结构与土木工程前沿(英文)》 2021年 第15卷 第4期   页码 1025-1037 doi: 10.1007/s11709-021-0741-9

摘要: The understanding of compressive and tensile behaviors of polypropylene fiber-reinforced cemented paste backfill (FR-CPB) play crucial roles in the successful implementation of reinforcement technique in underground mine backfilling operations. However, very limited studies have been performed to gain insight into the evolution of compressive and tensile behaviors and associated mechanical properties of FR-CPB under various curing temperatures from early to advanced ages. Thus, this study aims to investigate the time (7, 28, and 90 d)- and temperature (20°C, 35°C, and 45°C)-dependence of constitutive behavior and mechanical properties of FR-CPB. The obtained results show that pre- and post-failure behaviors of FR-CPB demonstrate strongly curing temperature-dependence from early to advanced ages. Moreover, the pseudo-hardening behavior is sensitive to curing temperature, especially at early ages. Furthermore, the mechanical properties including elastic modulus, material stiffness, strengths, brittleness, cohesion, and internal friction angle of FR-CPB show increasing trends with curing temperature as curing time elapses. Additionally, a predictive model is developed to capture the strong correlation between compressive and tensile strength of FR-CPB. The findings of this study will contribute to the successful implementation of FR-CPB technology.

关键词: cemented paste backfill     fiber reinforcement     constitutive behavior     temperature     tailings    

Discontinuous mechanical behaviors of existing shield tunnel with stiffness reduction at longitudinal

《结构与土木工程前沿(英文)》 2023年 第17卷 第1期   页码 37-52 doi: 10.1007/s11709-022-0920-3

摘要: An analytical model is proposed to estimate the discontinuous mechanical behavior of an existing shield tunnel above a new tunnel. The existing shield tunnel is regarded as a Timoshenko beam with longitudinal joints. The opening and relative dislocation of the longitudinal joints can be calculated using Dirac delta functions. Compared with other approaches, our method yields results that are consistent with centrifugation test data. The effects of the stiffness reduction at the longitudinal joints (α and β), the shearing stiffness of the Timoshenko beam GA, and different additional pressure profiles on the responses of the shield tunnel are investigated. The results indicate that our proposed method is suitable for simulating the discontinuous mechanical behaviors of existing shield tunnels with longitudinal joints. The deformation and internal forces decrease as α, β, and GA increase. The bending moment and shear force are discontinuous despite slight discontinuities in the deflection, opening, and dislocation. The deflection curve is consistent with the additional pressure profile. Extensive opening, dislocation, and internal forces are induced at the location of mutation pressures. In addition, the joints allow rigid structures to behave flexibly in general, as well as allow flexible structures to exhibit locally rigid characteristics. Owing to the discontinuous characteristics, the internal forces and their abrupt changes at vulnerable sections must be monitored to ensure the structural safety of existing shield tunnels.

关键词: tunnel–soil interaction     discontinuous analysis     longitudinal joints     existing shield tunnel     Timoshenko beam     Dirac delta function    

标题 作者 时间 类型 操作

Effects of elastic support on the dynamic behaviors of the wind turbine drive train

Shuaishuai WANG, Caichao ZHU, Chaosheng SONG, Huali HAN

期刊论文

Influence mechanism of dynamic and static liquid bridge forces on particle deposition behaviors in solar

Xueqing LIU, Xiaodong ZHAO, Luyi LU, Jianlan LI

期刊论文

Dynamic performance of submerged floating tunnel with different mooring styles subjected to anchor cable

期刊论文

Flocculation behaviors of a novel papermaking sludge-based flocculant in practical printing and dyeing

期刊论文

Thermal defluorination behaviors of PFOS, PFOA and PFBS during regeneration of activated carbon by molten

期刊论文

CFD simulation of jet behaviors in a binary gas-solid fluidized bed: comparisons with experiments

Pei PEI, Guiying WU, Bangting YU, Kai ZHANG, Jianchun JIANG, Dongsheng WEN,

期刊论文

高速润滑脂的弹流拖动特性

杨伯原,郑培斌,苏冰,吴勇军,邓四二

期刊论文

Analysis of molten metal spreading and solidification behaviors utilizing moving particle full-implicit

期刊论文

Cannabidiol prevents depressive-like behaviors through the modulation of neural stem cell differentiation

期刊论文

Controlling microbiological interfacial behaviors of hydrophobic organic compounds by surfactants in

ZHANG Dong,ZHU Lizhong

期刊论文

Endosulfan residues and farmers’ replacement behaviors of endosulfan in the north-west inland cotton

期刊论文

Creep and recovery behaviors of magnetorheological elastomers

Weihua LI, Yang ZHOU, Tongfei TIAN, Gursel ALICI,

期刊论文

Vibratory behaviors of Jeffcott system on cylindrical roller bearings

Hao WU, Jianwen WANG, Qi AN

期刊论文

Time- and temperature-dependence of compressive and tensile behaviors of polypropylene fiber-reinforced

期刊论文

Discontinuous mechanical behaviors of existing shield tunnel with stiffness reduction at longitudinal

期刊论文