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A toughness based deformation limit for X- and K-joints under brace axial tension

Bo GU,Xudong QIAN,Aziz AHMED

《结构与土木工程前沿（英文）》 2016年第10卷第3期页码 345-362 doi: 10.1007/s11709-016-0333-2

摘要： This study reports a deformation limit for the initiation of ductile fracture failure in fatigue-cracked circular hollow section (CHS) X- and K-joints subjected to brace axial tension. The proposed approach sets the deformation limit as the numerically computed crack driving force in a fatigue crack at the hot-spot location in the tubular joint reaches the material fracture toughness measured from standard fracture specimens. The calibration of the numerical procedure predicates on reported numerical computations on the crack driving force and previously published verification study against large-scale CHS X-joints with fatigue generated surface cracks. The development of the deformation limit includes a normalization procedure, which covers a wide range of the geometric parameters and material toughness levels. The lower-bound deformation limits thus developed follow a linear relationship with respect to the crack-depth ratio for both X- and K-joints. Comparison of the predicated deformation limit against experimental on cracked tubular X- and K-joints demonstrates the conservative nature of the proposed deformation limit. The proposed deformation limit, when extrapolated to a zero crack depth, provides an estimate on the deformation limits for intact X- and K-joints under brace axial loads.

关键词： circular hollow section (CHS) tubular joint fracture failure deformation limit J-integral

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Elasto-plastic fatigue crack growth analysis of plane problems in the presence of flaws using XFEM

Sachin KUMAR,A. S. SHEDBALE,I. V. SINGH,B. K. MISHRA

《结构与土木工程前沿（英文）》 2015年第9卷第4期页码 420-440 doi: 10.1007/s11709-015-0305-y

摘要： In this paper, elasto-plastic XFEM simulations have been performed to evaluate the fatigue life of plane crack problems in the presence of various defects. The stress-strain response of the material is modeled by Ramberg-Osgood equation. The von-Mises failure criterion has been used with isotropic hardening. The -integral for two fracture modes (mode-I and mode-II) is obtained by decomposing the displacement and stress fields into their symmetric and antisymmetric parts, then individual stress intensity factors are extracted from -integral. The fatigue life obtained by EPFM is found quite close to that obtained by LEFM.

关键词： XFEM von-Mises yield criterion isotropic hardening fatigue crack growth J-integral

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Trapezoidal Intuitionistic Fuzzy Aggregation Operator Based on Choquet Integral and Its Application to

Xi-hua Li,Xiao-hong Chen

《工程管理前沿（英文）》 2015年第2卷第3期页码 266-276 doi: 10.15302/J-FEM-2015048

摘要： The Choquet integral can serve as a useful tool to aggregate interacting criteria in an uncertain environment. In this paper, a trapezoidal intuitionistic fuzzy aggregation operator based on the Choquet integral is proposed for multi-criteria decision-making problems. The decision information takes the form of trapezoidal intuitionistic fuzzy numbers and both the importance and the interaction information among decision-making criteria are considered. On the basis of the introduction of trapezoidal intuitionistic fuzzy numbers, its operational laws and expected value are defined. A trapezoidal intuitionistic fuzzy aggregation operator based on the Choquet integral is then defined and some of its properties are investigated. A new multi-criteria decision-making method based on a trapezoidal intuitionistic fuzzy Choquet integral operator is proposed. Finally, an illustrative example is used to show the feasibility and availability of the proposed method.

关键词： multi-criteria decision making trapezoidal intuitionistic fuzzy numbers Choquet integral fuzzy measure aggregation operator

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Mesoscale fabrication of a complex surface for integral impeller blades

Xibin WANG,Tianfeng ZHOU,Lijing XIE,Li JIAO,Zhibing LIU,Zhiqiang LIANG,Pei YAN

《机械工程前沿（英文）》 2017年第12卷第1期页码 116-131 doi: 10.1007/s11465-017-0426-1

摘要：

Integral impeller is the most important component of a mini-engine. However, the machining of a mesoscale impeller with a complex integral surface is difficult because of its compact size and high accuracy requirement. A mesoscale component is usually manufactured by milling. However, a conventional milling tool cannot meet the machining requirements because of its size and stiffness. For the fabrication of a complex integral impeller, a micro-ball-end mill is designed in accordance with the non-instantaneous-pole envelope principle and manufactured by grinding based on the profile model of the helical groove and the mathematical model of the cutting edge curve. Subsequently, fractal theory is applied to characterize the surface quality of the integral impeller. The fractal theory-based characterization shows that the completed mesoscale integral impeller exhibits a favorable performance in terms of mechanical properties and morphological accuracy.

关键词： mesoscale fabrication micro-milling tool mesoscale milling impeller blade

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Stability and coupling dynamic behavior of nonlinear journal active electromagnetic bearing rotor system

LU Yanjun, HEI Di, WANG Yuan, DAI Rong, LU Yanjun, LIU Heng, YU Lie

《机械工程前沿（英文）》 2008年第3卷第2期页码 193-199 doi: 10.1007/s11465-008-0023-4

摘要： The stability and coupling dynamic behavior of a journal active electromagnetic bearing rotor system are analyzed. The gyroscopic effect is considered in the rotor model. The system equations are formulated by combining equations for rotor motion and decentralized proportional integral differential (PID) controllers. A method combining the predictor-corrector mechanism and the Netwon-Raphson method is presented to calculate the critical speed at the corresponding Hopf bifurcation point of the system. For periodic motions, a continuation method combining the predictor-corrector mechanism and shooting method is presented. Nonlinear unbalanced periodic motions and their stability margins are obtained using the shooting method and established continuation method for periodic motions. With the change of control parameters, the system local stability and bifurcation behaviors are obtained using the Floquet theory. The numerical examples show that the schemes not only significantly save computing cost, but also have high precision.

关键词： proportional integral bifurcation corresponding integral differential predictor-corrector mechanism

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Investigation on the integral output power model of a large-scale wind farm

BAO Nengsheng, MA Xiuqian, NI Weidou

《能源前沿（英文）》 2007年第1卷第1期页码 67-78 doi: 10.1007/s11708-007-0006-x

摘要： The integral output power model of a large-scale wind farm is needed when estimating the wind farm s output over a period of time in the future. The actual wind speed power model and calculation method of a wind farm made up of many wind turbine units are discussed. After analyzing the incoming wind flow characteristics and their energy distributions, and after considering the multi-effects among the wind turbine units and certain assumptions, the incoming wind flow model of multi-units is built. The calculation algorithms and steps of the integral output power model of a large-scale wind farm are provided. Finally, an actual power output of the wind farm is calculated and analyzed by using the practical measurement wind speed data. The characteristics of a large-scale wind farm are also discussed.

关键词： power model actual energy large-scale practical measurement

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清洁电力技术

Robin J. Batterham

《工程（英文）》 2020年第6卷第12期页码 1349-1350 doi: 10.1016/j.eng.2020.10.004

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Measurement and correlation of supercritical CO

Hiroshi MACHIDA, Ryosuke TAGUCHI, Yoshiyuki SATO, Louw J. FLOURUSSE, Cor J. PETERS, Richard L. SMITH

《化学科学与工程前沿（英文）》 2009年第3卷第1期页码 12-19 doi: 10.1007/s11705-009-0151-3

摘要： Ionicliquids combined with supercritical fluid technology hold great promise as working solvents for developing compact processes. Ionic liquids, which are organic molten salts, typically have extremely low volatility and high functionality, but possess high viscosities, surface tensions and low diffusion coefficients, which can limit their applicability. CO , on the other hand, especially in its supercritical state, is a green solvent that can be used advantageously when combined with the ionic liquid to provide viscosity and surface tension reduction and to promote mass transfer. The solubility of CO in the ionic liquid is key to estimating the important physical properties that include partition coefficients, viscosities, densities, interfacial tensions, thermal conductivities and heat capacities needed in contactor design. In this work, we examine a subset of available high pressure pure component ionic liquid PVT data and high pressure CO - ionic liquid solubility data and report new correlations for CO -ionic liquid systems with equations of state that have some industrial applications including: (1) general, (2) fuel desulfurization, (3) CO capture, and (4) chiral separation. New measurements of solubility data for the CO and 1-butyl-3-methylimidazolium octyl sulfate, [bmim][OcSO ] system are reported and correlated. In the correlation of the CO ionic liquid phase behavior, the Peng-Robinson and the Sanchez-Lacombe equations of state were considered and are compared. It is shown that excellent correlation of CO solubility can be obtained with either equation and they share some common characteristics regarding interaction parameters. In the Sanchez-Lacombe equation, parameters that are derived from the supercritical region were found to be important for obtaining good correlation of the CO -ionic liquid solubility data.

关键词： compact processes chiral ionic liquids separations thermodynamic properties equations of state

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Merits and limitations of TiO

Yu Yang, Hassan Javed, Danning Zhang, Deyi Li, Roopa Kamath, Kevin McVey, Kanwartej Sra, Pedro J.J.

《化学科学与工程前沿（英文）》 2017年第11卷第3期页码 387-394 doi: 10.1007/s11705-017-1657-8

摘要： Heavy hydrocarbons (HHCs) in soils impacted by crude oil spills are generally recalcitrant to biodegradation due to their low bioavailability and complex chemical structure. In this study, soils were pretreated with varying concentrations of ultraviolet radiation A (UVA) or ultraviolet radiation C (UVC) activated titanium dioxide (TiO ) (1%–5%) under varying moisture conditions (0%–300% water holding capacity (WHC)) to enhance biodegradation of HCCs and shorten remediation timeframes. We demonstrate that pretreatment of impacted soils with UVC-activated TiO in soil slurries could enhance bioremediation of HHCs. ?Total petroleum hydrocarbon (TPH) removal after 24 h exposure to UVC (254 nm and 4.8 mW/cm ) was (19.1±1.6)% in slurries with 300% WHC and 5 wt-% TiO . TPH removal was non-selective in the C15-C36 range and increased with moisture content and TiO concentration. In a 10-d bioremediation test, TPH removal in treated soil increased to (26.0±0.9)%, compared to (15.4±0.8)% for controls without photocatalytic pre-treatment. Enhanced biodegradation was also confirmed by respirometry. This suggests that addition of UVC-activated TiO to soil slurries can transform recalcitrant hydrocarbons into more bioavailable and biodegradable byproducts and increase the rate of subsequent biodegradation. However, similar results were not observed for soils pretreated with UVA activated TiO . This suggests that activation of TiO by sunlight and direct addition of TiO to unsaturated soils within landfarming setting may not be a feasible approach. Nevertheless, less than 1% of UVA (7.5 mW/cm ) or UVC (1.4 mW/cm ) penetrated beyond 0.3 cm soil depth, indicating that limited light penetration through soil would hinder the ability of TiO to enhance soil bioremediation under land farming conditions.

关键词： TiO₂ pretreatment bioremediation total petroleum hydrocarbons ultraviolet

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Ribozyme and the mechanisms that underlie RNA catalysis

Timothy J. Wilson,Yijin Liu,David M. J. Lilley

《化学科学与工程前沿（英文）》 2016年第10卷第2期页码 178-185 doi: 10.1007/s11705-016-1558-2

摘要： Ribozymes are widespread, and catalyze some extremely important reactions in the cell. Mechanistically most fall into one of two classes, using either metal ions or general acid-base catalysis. The nucleolytic ribozymes fall into the latter class, mostly using nucleobases. A sub-set of these use a combination of guanine base plus adenine acid to catalyze the cleavage reaction. New ribozymes are still being discovered at regular intervals and we can speculate on the potential existence of ribozymes that catalyze chemistry beyond phosphoryl transfer reactions, perhaps using small-molecule coenzymes.

关键词： RNA catalysis RNA structure catalytic mechanism

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基于改进级联观测器的永磁同步电机智能分数阶积分滑模控制 Research Articles

肖玲斐1,2,马磊明3,黄欣浩1

《信息与电子工程前沿（英文）》 2022年第23卷第2期页码 328-338 doi: 10.1631/FITEE.2000317

摘要：提出一种基于改进级联观测器的智能分数阶积分滑模控制（FOISMC）策略。首先，针对永磁同步电机设计了分数阶积分滑模控制器，该控制器有良好跟踪性能，具有强鲁棒性，且能有效削弱抖振。所提策略结合了积分能消除稳态跟踪误差和分数阶微积分灵活的优点。其次，提出一种改进的级联观测器，能获得较小的转子信息观测误差。所设计级联观测器结合了自适应滑模观测器和扩展高增益观测器。此外，利用改进的变速灰狼优化算法优化控制器参数。最后，在综合考虑模型不确定性和外部干扰的情况下，通过仿真和实验验证了所提策略的有效性。

关键词：永磁同步电机；分数阶积分滑模；优化算法；无传感器控制；观测器

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烃污染土壤的热处理工艺：针对可持续修复工艺进展的综述

Masiello, Gabriel Sabadell, Pedro J. J. Alvarez

《工程（英文）》 2016年第2卷第4期页码 426-437 doi: 10.1016/J.ENG.2016.04.005

摘要：

在受烃污染的土壤和底泥的修复处理工艺中，热处理工艺因其能快速且稳定地达到修复标准而占有重要地位。然而，持续高温属于能源密集型操作，且可破坏土壤性质，因此尽管此工艺被广泛应用，关于这些工艺的环境兼容性和可持续性却极少被报道。鉴于此，我们对几个针对烃污染土壤的常用热处理工艺进行了概述，对它们的潜在环境影响进行了评估；并基于能源需求、水需求、系统生态和土壤科学的全面考虑，提出了可持续且影响较小的发展框架。至今还没有一种通用适合的热处理工艺。工艺的恰当选择要根据污染状况( 包括环境中存在的烃种类) 和场地特征( 如被污染土壤的性质、水含量和热敏性) 而定。总之，处理工程与土壤科学、生态系统和植物生物学研究的有机结合是攻克技术瓶颈、提高去除率和促进热处理工艺可持续性发展的关键所在。

关键词：土壤分解土地改良焚烧裂解解吸

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Aseismic smart building isolation systems under multi-level earthquake excitations: Part I, conceptual design and nonlinear analysis

Min-Ho CHEY,J. Geoffrey CHASE,John B. MANDER,Athol J. CARR

《结构与土木工程前沿（英文）》 2015年第9卷第3期页码 286-296 doi: 10.1007/s11709-015-0307-9

摘要： As a novel structural control strategy, tuned mass damper (TMD) inspired passive and semi-active smart building isolation systems are suggested to reduce structural response and thus mitigate structural damage due to earthquake excitations. The isolated structure’s upper stories can be utilized as a large scaled TMD, and the isolation layer, as a core design point, between the separated upper and lower stories entails the insertion of rubber bearings and (i) viscous dampers (passive) or (ii) resettable devices (semi-active). The seismic performance of the suggested isolation systems are investigated for 12-story reinforced concrete moment resisting frames modeled as “10+ 2” stories and “8+ 4” stories. Passive viscous damper or semi-active resettable devices are parametrically evaluated through the optimal design principle of a large mass ratio TMD. Statistical performance metrics are presented for 30 earthquake records from the three suites of the SAC project. Based on nonlinear structural models, including P-delta effects and modified Takeda hysteresis, the inelastic time history analyses are conducted to compute the seismic performances across a wide range of seismic hazard intensities. Results show that semi-active smart building isolation systems can effectively manage seismic response for multi-degree-of freedom (MDOF) systems across a broader range of ground motions in comparison to uncontrolled case and passive solution.

关键词： tuned mass damper smart building isolation resettable device non-linear statistical assessment

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Purification of

PIETZSCH, J. ULRICH

《化学科学与工程前沿（英文）》 2013年第7卷第1期页码 37-42 doi: 10.1007/s11705-013-1303-z

摘要： Here a case study of -asparaginase II out of a recombinant is presented. The target protein was obtained by simple cell disintegration and acetone precipitation. The -asparaginase II has been crystallized in three different forms in the following microbatch crystallization. The rod-shaped crystals (~400 μm edge length) were obtained at either 8°C or 22°C after 17 h by addition of PEG . The rectangular-shaped crystals were obtained after further recrystallization of the rod-shaped crystals. The rhombic-shaped crystals formed at 8°C after 12 days when cold ethanol was used instead of PEG . All crystallizations were performed in tris-acetate buffer (50 mmol·L , pH 5.1). By crystallization, the specific activity of -asparaginase II has increased 5-fold. The protein content and the purity of the crystals were evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The more concentrated -asparaginase II out of an extract mixture and the presence of only less minor proteins after crystallization demonstrates that crystallization is an effective and mild method to purify the target protein. The single crystal X-ray diffraction pattern reveals that the crystals are proteins and the X-ray powder diffraction (XRPD) pattern shows clearly that the crystals forming in PEG and ethanol have different crystal structures.

关键词： protein crystallization L-asparaginase II purification