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Numerical analysis and experimental investigation of modal properties for the gearbox in wind turbine

Pengxing YI,Peng HUANG,Tielin SHI

《机械工程前沿（英文）》 2016年 第11卷 第4期   页码 388-402 doi: 10.1007/s11465-016-0404-z

摘要：

Wind turbine gearbox (WTG), which functions as an accelerator, ensures the performance and service life of wind turbine systems. This paper examines the distinctive modal properties of WTGs through finite element (FE) and experimental modal analyses. The study is performed in two parts. First, a whole system model is developed to investigate the first 10 modal frequencies and mode shapes of WTG using flexible multi-body modeling techniques. Given the complex structure and operating conditions of WTG, this study applies spring elements to the model and quantifies how the bearings and gear pair interactions affect the dynamic characteristics of WTGs. Second, the FE modal results are validated through experimental modal analyses of a 1.5 WM WTG using the frequency response function method of single point excitation and multi-point response. The natural frequencies from the FE and experimental modal analyses show favorable agreement and reveal that the characteristic frequency of the studied gearbox avoids its eigen-frequency very well.

关键词： wind turbine gearbox     modal analysis     finite element analysis     modal frequency     bearing equivalence    

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The calculation of equivalence factor for ecological footprints in China: a methodological note

Moucheng LIU,Wenhua LI,Dan ZAHNG,Ning SU

《环境科学与工程前沿（英文）》 2015年 第9卷 第6期   页码 1015-1024 doi: 10.1007/s11783-014-0670-0

摘要： The Ecological Footprint (EF), a physical indicator to measure the extent of humanity’s use of natural resources, has gained much attention since it was first used by Wackernagel and Rees in 1996. In order to appraise land area types with different levels of productivity, they introduced the concept of an equivalence factor. This relates to the average primary biomass productivities of different types of land (i.e. arable land, pasture, forest, water/fishery, built-up land and fossil energy land) to the regional average primary biomass productivity of all land types in a given year. Hence, the equivalence factor is an important parameter in the EF model and it directly affects the reliability of all results. Thus, this article calculates equivalence factors on the national and provincial levels in China based on Net Primary Production (NPP) from MODIS 1 km data in 2008. Firstly, based on the Light Utility Efficiency and CASA model, the NPP of different biologically productive lands of China and of different provinces was calculated. Secondly, China’s equivalence factor for 6 land area types was calculated based on NPP: arable land and built-up land has an equivalence factor of 1.71, forest and fossil energy land has a factor of 1.41, pasture has a factor of 0.44 and water/fishery 0.35; Finally, the equivalence factor of 6 land area types in different provinces was also calculated. The NPP of each ecosystem type varies along with the equivalence factor in different provinces. However, the ranking of the equivalence factors in different provinces remain the same, with that of arable land being the largest, and the water/fishery being the smallest.

关键词： ecological footprint     equivalence factor     net primary production     biological capacity     land types    

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通过一个等价雷诺数揭示层流到湍流的转捩区域 Article

陈晓东

《工程（英文）》 2019年 第5卷 第3期   页码 576-579 doi: 10.1016/j.eng.2018.09.013

摘要：

Flow transition from laminar to turbulent mode (and vice versa)—that is, the initiation of turbulence—is one of the most important research subjects in the history of engineering. Even for pipe flow, predicting the onset of turbulence requires sophisticated instrumentation and/or direct numerical simulation, based on observing the instantaneous flow structure formation and evolution. In this work, a local Reynolds number equivalence γ (ratio of local inertia effect to viscous effect) is seen to conform to the Universal Law of the Wall, where γ = 1 represents a quantitative balance between the abovementioned two effects. This coincides with the wall layer thickness (y+ = 1, where y+ is the dimensionless distance from the wall surface defined in the Universal Law of the Wall). It is found that the characteristic of how the local derivative of γ against the local velocity changes with increasing velocity determines the onset of turbulence. For pipe flow, γ ≈ 25, and for plate flow, γ ≈ 151.5. These findings suggest that a certain combination of γ and velocity (nonlinearity) can qualify the source of turbulence (i.e., generate turbulent energy). Similarly, a re-evaluation of the previous findings reveals that only the geometrically narrow domain can act locally as the source of turbulence, with the rest of the flow field largely being left for transporting and dissipating. This understanding will have an impact on the future large-scale modeling of turbulence.

关键词： 局部等价雷诺数     转捩     壁面律     管流     平板流动     建模    

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Iterative HOEO fusion strategy: a promising tool for enhancing bearing fault feature

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0725-z

摘要： As parameter independent yet simple techniques, the energy operator (EO) and its variants have received considerable attention in the field of bearing fault feature detection. However, the performances of these improved EO techniques are subjected to the limited number of EOs, and they cannot reflect the non-linearity of the machinery dynamic systems and affect the noise reduction. As a result, the fault-related transients strengthened by these improved EO techniques are still subject to contamination of strong noises. To address these issues, this paper presents a novel EO fusion strategy for enhancing the bearing fault feature nonlinearly and effectively. Specifically, the proposed strategy is conducted through the following three steps. First, a multi-dimensional information matrix (MDIM) is constructed by performing the higher order energy operator (HOEO) on the analysis signal iteratively. MDIM is regarded as the fusion source of the proposed strategy with the properties of improving the signal-to-interference ratio and suppressing the noise in the low-frequency region. Second, an enhanced manifold learning algorithm is performed on the normalized MDIM to extract the intrinsic manifolds correlated with the fault-related impulses. Third, the intrinsic manifolds are weighted to recover the fault-related transients. Simulation studies and experimental verifications confirm that the proposed strategy is more effective for enhancing the bearing fault feature than the existing methods, including HOEOs, the weighting HOEO fusion, the fast Kurtogram, and the empirical mode decomposition.

关键词： higher order energy operator     fault diagnosis     manifold learning     rolling element bearing     information fusion    

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New analysis model for rotor-bearing systems based on plate theory

Zhinan ZHANG, Mingdong ZHOU, Weimin DING, Huifang MA

《机械工程前沿（英文）》 2019年 第14卷 第4期   页码 461-473 doi: 10.1007/s11465-019-0525-2

摘要： The purpose of this work is to develop a new analysis model for angular-contact, ball-bearing systems on the basis of plate theory instead of commonly known approaches that utilize spring elements. Axial and radial stiffness on an annular plate are developed based on plate, Timoshenko beam, and plasticity theories. The model is developed using theoretical and inductive methods and validated through a numerical simulation with the finite element method. The new analysis model is suitable for static and modal analyses of rotor-bearing systems. Numerical examples are presented to reveal the effectiveness and applicability of the proposed approach.

关键词： rotor-bearing system     rolling element bearing     plate theory     finite element analysis    

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API-based assessment on urban air environment bearing capability in China

Jinnan WANG,Jing ZHANG,Hongqiang JIANG,Yaling LU

《环境科学与工程前沿（英文）》 2015年 第9卷 第6期   页码 1049-1055 doi: 10.1007/s11783-014-0662-0

摘要： Given the complexity and time-consuming of the conventional environmental capacity based assessment on air environment carrying capacity; a new method for assessing urban air environment carrying capacity based on air pollution index (API) is presented. By using this new method, the air environmental bearing capability of 333 cities at the prefecture level and above is assessed. The results show that of the 333 cities 9.6% is of high bearing capability, 34.5% relatively high bearing capability, 52.6% medium bearing capability, 2.7% low capability, and 0.6% is of weak bearing capability; in terms of regional distribution, the western region is of relatively high air environment bearing capability, followed by north-eastern and eastern regions, and the ambient air quality in the middle region is quite poor; among the 12 urban agglomerations in key regions, Pearl River delta, west side of Taiwan Strait and Chengdu-Chongqing agglomerations are of relatively high carrying capacity while other agglomerations are of medium bearing capability. The assessment results imply that the existing air quality standard (GB3095-1996) is quite unsound.

关键词： air pollution index (API)     air environment bearing capability     key city     assessment method    

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基于动态等值及数值积分灵敏度的快速紧急控制策略计算 Research Articles

Yi-fan GAO, Jian-quan WANG, Tan-nan XIAO, Dao-zhuo JIANG

《信息与电子工程前沿（英文）》 2019年 第20卷 第8期   页码 1119-1132 doi: 10.1631/FITEE.1700389

摘要： 为减少大规模电力系统暂态稳定分析的计算时间，实现紧急控制策略的实时计算，提出基于实时动态等值的快速暂态稳定仿真及紧急控制策略算法。通过故障后短时间的全系统数值积分计算，将发电组实时分群并进行模型聚合，并运用提出的等值系统节点导纳矩阵快速计算方法求取等值系统网络参数。在获得的动态等值系统上完成暂态稳定仿真计算和基于数值积分灵敏度的紧急控制决策计算。最终，经过等值系统向原始系统反向映射，获得原始系统的紧急控制策略。在包含496台发电机和5075节点的区域电网中进行仿真计算。结果表明该算法可获得准确的暂态稳定计算结果和有效的紧急控制策略，与常规暂态稳定数值积分算法以及基于数值积分灵敏度的紧急控制算法相比，大幅减少了计算时间。

关键词： 紧急控制；暂态稳定；数值积分；动态等值；数值积分灵敏度    

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Experimental evaluation of a 35 kVA downdraft gasifier

Ashok Jayawant Rao KECHE, Gaddale AMBA PRASAD RAO

《能源前沿（英文）》 2013年 第7卷 第3期   页码 300-306 doi: 10.1007/s11708-013-0247-9

摘要： Energy conversion systems based on biomass are particularly interesting because biomass utilization effectively closes the carbon cycle besides achieving self-sustainability. Biomass is particularly useful for highly populated and agriculture dependent economic nations like China and India. A compact and cost effective downdraft gasification system was developed. The present paper describes an experimental investigation on a biomass based gasifier engine system with a capacity of 35 kVA for power generation application. The problem of cooling and cleaning the hot and dirty gas from the gasifier has been satisfactorily solved by the effective cooling and filtration system. The gasifier developed is observed to be operation friendly. The quality of gas was evaluated in terms of its composition, conversion efficiency and total particulate matter. The maximum output of the power plant was obtained at the combustion zone temperature of 850oC. The experimental investigations showed that the percentage reduction in total particulate matter is 89.32%. The conversion efficiency of the biomass gasifier is found to be dependent on the operation conditions and fuel properties of the gasifier. The optimum value of equivalence ratio was observed to be 0.3134 for achieving the maximum gas conversion efficiency of the present gasifier configuration.

关键词： biomass     gasification     producer gas     equivalence ratio     total particulate matter     conversion efficiency of gasifier    

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The convexity about ultimate bearing hypersurfaces of structures

Chengxi GUO,Tingting GUO

《结构与土木工程前沿（英文）》 2016年 第10卷 第4期   页码 456-461 doi: 10.1007/s11709-016-0334-1

摘要： The relationship between the convexity on the ultimate bearing surface of a structure and the second-order effects of loads is discussed. All of generalized non-overload forces acted on a structure forms a convex set when ignoring the second-order effects (coupling effects between the generalized forces). It is true also when the Hessian matrix composed of the second-order partial derivatives on the hypersurface about the ultimate bearing of the structure is negative definite. The outward convexity is kept when the surface is expressed by certain dimensionless parameters. A series of properties based on the convexity are pointed out. Some applications in the analysis of bearing capacity of structures were illustrated with examples. The study shows that an evaluation about the bearing capacity state of a complex structure can be made on the basis of several points on the surface of the ultimate bearing of the structure.

关键词： service     limit load     ultimate bearing surface     convexity     generalized force     generalized displacement     frame structure    

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Foundations bearing capacity subjected to seepage by the kinematic approach of the limit analysis

Mehdi VEISKARAMI, Ghasem HABIBAGAHI

《结构与土木工程前沿（英文）》 2013年 第7卷 第4期   页码 446-455 doi: 10.1007/s11709-013-0227-5

摘要： An estimate of the ultimate load on foundations on soil layers subject to groundwater flow has been presented. The kinematic approach of the limit analysis was employed to find the upper-bound limit of the bearing capacity. Both smooth and rough base strip foundations were considered associated with different collapse patterns. Presence of the groundwater flow leads to a non-symmetric collapse pattern, i.e., a weak side and a strong side in two-sided collapse patterns, depending on the direction of the flow. It was found that the bearing capacity has a decreasing trend with increase in the groundwater flow gradient and hence, a reduction factor has been introduced to the third term in the bearing capacity equation as a function of the flow gradient.

关键词： foundation     bearing capacity     limit analysis     numerical computation     plasticity     seepage    

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Undrained seismic bearing capacity of strip footing adjacent to a heterogeneous excavation

《结构与土木工程前沿（英文）》 2023年 第17卷 第4期   页码 566-583 doi: 10.1007/s11709-023-0905-x

摘要： The analysis of the bearing capacity of strip footings sited near an excavation is critical in geotechnics. In this study, the effects of the geometrical features of the excavation and the soil strength properties on the seismic bearing capacity of a strip footing resting on an excavation were evaluated using the lower and upper bounds of the finite element limit analysis method. The effects of the setback distance ratio (L/B), excavation height ratio (H/B), soil strength heterogeneity (kB/cu), and horizontal earthquake coefficient (kh) were analyzed. Design charts and tables were produced to clarify the relationship between the undrained seismic bearing capacity and the selected parameters.

关键词： excavation     finite element limit analysis     heterogeneous soil     strip footing     undrained bearing capacity    

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methane/air mixtures with multiple orifices in a large bore constant volume chamber: effect of air-fuel equivalence

Xiang LI, Wenzheng ZHANG, Zhong HUANG, Dehao JU, Li HUANG, Mingzhi FENG, Xingcai LU, Zhen HUANG

《能源前沿（英文）》 2019年 第13卷 第3期   页码 483-493 doi: 10.1007/s11708-019-0631-1

摘要： Liquefied natural gas (LNG), mainly composed of methane, is in progress to substitute diesel fuel in heavy-duty marine engine for practical, economic, and environmental considerations. However, natural gas is relatively difficult to be ignited in a large bore combustion chamber. A combustion enhancement technique called pre-chamber turbulent jet ignition (TJI) can permit combustion and flame propagation in a large-bore volume. To investigate the effect of air-fuel equivalence ratio and pre-mixed pressure on pre-chamber TJI of methane/air mixtures with multiple orifices in a large bore volume, experimental tests and computational simulations were implemented to study the discharge of hot turbulent jets from six orifices of the pre-chamber. Different initial pressures and air-fuel equivalence ratios were considered to analyze the characteristics of TJI. The asymmetry of the turbulent jet actuated from six different orifices were found due to the asymmetric orientation of the spark plug, resulting in the inhomogeneous distribution of combustion in the constant volume chamber, which should be considered seriously in the marine engine design. Besides, as the premixed pressure increases, it has more effect on the flame propagation and plays a more important role, as it further increases.

关键词： marine engine     natural gas     methane     turbulent jet ignition (TJI)     pre-chamber    

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Influence of the Mechanical Seals on the Dynamic Performance of Rotor–Bearing Systems

XU Hua, ZHU Jun

《机械工程前沿（英文）》 2006年 第1卷 第1期   页码 96-100 doi: 10.1007/s11465-005-0008-5

摘要：

In this paper, to consider the effects of mechanical seals, a lumped-mass model and the transfer matrix method are used to establish the equations for the dynamics performance of rotor bearing system. The general inverted iteration method is also used to solve the eigenvalue problem of these equations. To check the response of the rotor bearing system under unbalance motivation, the Gauss method is used to calculate the dynamic response of the constrained vibration. The results, based on the dynamic properties calculation of a typical mechanical spiral seal, such as stiffness coefficients and damping coefficients, exert the influence of the mechanical seal on the rotor bearing system of the high-speed machinery. Meanwhile, some structure parameters that may affect the dynamic performance and forced vibration under unbalance motivation of the rotor bearing system considering mechanical seals are analyzed in the paper. The analysis results show that the mechanical seal more or less has effects on the rotor bearing system. The mechanical seal has much more effects on the flexible rotor bearing system than on the rigid one. For instance, in a certain case, if the effects of the mechanical seal were taken into account, the system s critical speed may increase by 70 80%.

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Ultimate bearing capacity of strip footing resting on clay soil mixed with tire-derived aggregates

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 1016-1024 doi: 10.1007/s11709-021-0751-7

摘要： This study investigated the use of recycled tire-derived aggregate (TDA) mixed with kaolin as a method of increasing the ultimate bearing capacity ( UBC) of a strip footing. Thirteen 1g physical modeling tests were prepared in a rigid box of 0.6 m × 0.9 m in plan and 0.6 m in height. During sample preparation, 0%, 20%, 40%, or 60% (by weight) of powdery, shredded, small-sized granular (G 1–4 mm) or large-sized granular (G 5–8 mm) TDA was mixed with the kaolin. A strip footing was then placed on the stabilized kaolin and was caused to fail under stress-controlled conditions to determine the UBC. A rigorous 3D finite element analysis was developed in Optum G-3 to determine the UBC values based on the experimental test results. The experimental results showed that, except for the 20% powdery TDA, the TDA showed an increase in the UBC of the strip footing. When kaolin mixed with 20% G (5–8 mm), the UBC showed a threefold increase over that for the unreinforced case. The test with 20% G (1–4 mm) recorded the highest subgrade modulus. It was observed that the UBC calculated using finite element modeling overestimated the experimental UBC by an average of 9%.

关键词： kaolin     physical modeling tests     stabilization     numerical modeling    

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Temperature control of transfer roller’s bearing based on finite element analysis

Peng ZHANG, Yourong LI, Han XIAO

《机械工程前沿（英文）》 2009年 第4卷 第2期   页码 215-218 doi: 10.1007/s11465-009-0026-9

摘要： After a heat preservation cover is installed on the main rolling line, the heat dissipation environment of the transfer roller working on the heat preservation cover is changed. To ensure the normal production, a reasonable working jet capacity of the roller neck is derived. First, a globe model of the transfer roller is built for finite element analysis. Second, the sub-model of the fixed end bearing is built and the boundary condition of the sub-model is supplied by the results of the globe model. The analysis result of the sub-model shows that the temperature of the transfer roller bearing exceeds 85°C a rolling periodicity later. With finite element analysis, the heat flux is obtained and the minimum working jet capacity is derived.

关键词： transfer roller bearing     finite element analysis     sub-model     temperature control    

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标题 作者 时间 类型 操作

Numerical analysis and experimental investigation of modal properties for the gearbox in wind turbine

Pengxing YI,Peng HUANG,Tielin SHI

期刊论文

The calculation of equivalence factor for ecological footprints in China: a methodological note

Moucheng LIU,Wenhua LI,Dan ZAHNG,Ning SU

期刊论文

通过一个等价雷诺数揭示层流到湍流的转捩区域

陈晓东

期刊论文

Iterative HOEO fusion strategy: a promising tool for enhancing bearing fault feature

期刊论文

New analysis model for rotor-bearing systems based on plate theory

Zhinan ZHANG, Mingdong ZHOU, Weimin DING, Huifang MA

期刊论文

API-based assessment on urban air environment bearing capability in China

Jinnan WANG,Jing ZHANG,Hongqiang JIANG,Yaling LU

期刊论文

基于动态等值及数值积分灵敏度的快速紧急控制策略计算

Yi-fan GAO, Jian-quan WANG, Tan-nan XIAO, Dao-zhuo JIANG

期刊论文

Experimental evaluation of a 35 kVA downdraft gasifier

Ashok Jayawant Rao KECHE, Gaddale AMBA PRASAD RAO

期刊论文

The convexity about ultimate bearing hypersurfaces of structures

Chengxi GUO,Tingting GUO

期刊论文

Foundations bearing capacity subjected to seepage by the kinematic approach of the limit analysis

Mehdi VEISKARAMI, Ghasem HABIBAGAHI

期刊论文

Undrained seismic bearing capacity of strip footing adjacent to a heterogeneous excavation

期刊论文

methane/air mixtures with multiple orifices in a large bore constant volume chamber: effect of air-fuel equivalence

Xiang LI, Wenzheng ZHANG, Zhong HUANG, Dehao JU, Li HUANG, Mingzhi FENG, Xingcai LU, Zhen HUANG

期刊论文

Influence of the Mechanical Seals on the Dynamic Performance of Rotor–Bearing Systems

XU Hua, ZHU Jun

期刊论文

Ultimate bearing capacity of strip footing resting on clay soil mixed with tire-derived aggregates

期刊论文

Temperature control of transfer roller’s bearing based on finite element analysis

Peng ZHANG, Yourong LI, Han XIAO

期刊论文