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Innovative seismic retrofitting strategy of added stories isolation system

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

《结构与土木工程前沿(英文)》 2013年 第7卷 第1期   页码 13-23 doi: 10.1007/s11709-013-0195-9

摘要: The seismic performance of “added stories isolation” (ASI) systems are investigated for 12-story moment resisting frames. The newly added and isolated upper stories on the top of the existing structure are rolled to act as a large tuned mass damper (TMD) to overcome the limitation of the size of tuned mass, resulting to “12+2” and “12+4” stories building configurations. The isolation layer, as a core design strategy, is optimally designed based on optimal TMD design principle, entailing the insertion of passive flexible laminated rubber bearings to segregate two or four upper stories from a conventionally constructed lower superstructure system. Statistical performance metrics are presented for 30 earthquake records from the 3 suites of the SAC project. Time history analyses are used to compute various response performances and reduction factors across a wide range of seismic hazard intensities. Results show that ASI systems can effectively manage seismic response for multi-degree-of freedom (MDOF) systems across a broader range of ground motions without requiring burdensome extra mass. Specific results include the identification of differences in the number of added story by which the suggested isolation systems remove energy.

关键词: added stories     seismic isolation     tuned mass damper     parametric optimization     statistical method    

H control in the frequency domain for a semi-active floor isolation system

Yundong SHI, Tracy C BECKER, Masahiro KURATA, Masayoshi NAKASHIMA

《结构与土木工程前沿(英文)》 2013年 第7卷 第3期   页码 264-275 doi: 10.1007/s11709-013-0214-x

摘要: A floor isolation system installed in a single floor or room in a fixed base structure is designed to protect equipment. With this configuration, the input motions to the floor isolation from the ground motions are filtered by the structure, leaving the majority of the frequency content of the input motion lower than the predominant frequency of the structure. The floor isolation system should minimize the acceleration to protect equipment; however, displacement must also be limited to save floor space, especially with long period motion. Semi-active control with an control was adopted for the floor isolation system and a new input shaping filter was developed to account for the input motion characteristics and enhance the effectiveness of the control. A series of shake table tests for a semi-active floor isolation system using rolling pendulum isolators and a magnetic-rheological damper were performed to validate the control. Passive control using an oil damper was also tested for comparison. The test results show that the control effectively reduced acceleration for short period motions with frequencies close to the predominant frequency of the structure, as well as effectively reduced displacement for long period motions with frequencies close to the natural frequency of the floor isolation system. The control algorithm proved to be more advantageous than passive control because of its capacity to adjust control strategies according to the different motion frequency characteristics.

关键词: semi-active     floor isolation     H control     MR damper     shaping filter     shaking table test    

Vibration characteristics and machining performance of a novel perforated ultrasonic vibration platform

《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0730-2

摘要: Ultrasonic vibration-assisted grinding (UVAG) is an advanced hybrid process for the precision machining of difficult-to-cut materials. The resonator is a critical part of the UVAG system. Its performance considerably influences the vibration amplitude and resonant frequency. In this work, a novel perforated ultrasonic vibration platform resonator was developed for UVAG. The holes were evenly arranged at the top and side surfaces of the vibration platform to improve the vibration characteristics. A modified apparent elasticity method (AEM) was proposed to reveal the influence of holes on the vibration mode. The performance of the vibration platform was evaluated by the vibration tests and UVAG experiments of particulate-reinforced titanium matrix composites. Results indicate that the reasonable distribution of holes helps improve the resonant frequency and vibration mode. The modified AEM, the finite element method, and the vibration tests show a high degree of consistency for developing the perforated ultrasonic vibration platform with a maximum frequency error of 3%. The employment of ultrasonic vibration reduces the grinding force by 36% at most, thereby decreasing the machined surface defects, such as voids, cracks, and burnout.

关键词: ultrasonic vibration-assisted grinding     perforated ultrasonic vibration platform     vibration characteristics     apparent elasticity method     grinding force     surface integrity    

Isolation and application of predatory

Ran Yu, Shiwen Zhang, Zhoukai Chen, Chuanyang Li

《环境科学与工程前沿(英文)》 2017年 第11卷 第1期 doi: 10.1007/s11783-017-0900-3

摘要: Indigenous predatory BALO strains were successfully isolated from activated sludge. Sludge SRF and CST were significantly reduced by BALOs induced biolysis process. The increase of BALO input dosage promoted the sludge biolysis efficiency. Sludge biolysis disintegrated flocs and lysed cells for internal water release. The optimal sludge biolysis time was 24 h and no pH adjustment was needed. -and-like organisms (BALOs) are a group of ubiquitous and obligate predatory bacteria and commonly used as biocontrol agents. In this study, an efficient, environmental-friendly, and convenient BALOs encouraged municipal waste sludge biolysis pretreatment technique was developed and investigated for dewaterability enhancement of excess waste sludge. The indigenous predatory BALOs were successfully isolated from the sludge for biolysis treatment. Without any chemical addition or pH adjustment, the sludge specific resistance (SRF) and capillary suction time (CST) were significantly reduced by as high as 53.4% and 23.8%, respectively within 24 h’s treatment, which would further be lowered with the increase of BALOs input dosage. However, the continuous extension of reaction time would worsen the sludge dewaterability. The decreases of SRF and CST accompanied with the increases of sludge disintegration degree and soluble chemical oxygen demand, nitrogen, and phosphorus concentrations all emphasized the contributions of BALOs’ predation activities to sludge disturbance, cell lysis, and consequently the release of sludge intracellular water to finally effectively improve the sludge dewaterability and disposal efficiency.

关键词: Bdellovibrio-and-like organisms (BALOs)     Biolysis     Activated sludge     Dewaterability     Predation    

Novel polymorphic EST-based microsatellite marker isolation and characterization from

Manosh Kumar BISWAS,Peng CHEN,Mohamed Hamdy AMAR,Xiuxin DENG

《农业科学与工程前沿(英文)》 2015年 第2卷 第1期   页码 60-65 doi: 10.15302/J-FASE-2015048

摘要: Novel simple sequence repeat (SSR) markers were developed to evaluate their utility for genetic diversity and breeding studies of and related species. A total of 108 primer pairs were characterized by PCR amplification experiments. Among these, 61 were polymorphic and transferable to other citrus species. The number of alleles per locus ranged from 2 to 6, with an average of 2.37 alleles per locus. The expected heterozygosity and observed heterozygosity ranged from 0 to 0.83 and 0 to 1.00, respectively. These novel polymorphic SSR markers will be useful for citrus cultivar identification and evaluation as well as breeding studies.

关键词: microsatellite     polymorphism     Poncirus trifoliata    

seismic response control on top of Three-Gorges ship lift towers using magnetorheological intelligent isolation

Weilian QU, Jianwei TU

《结构与土木工程前沿(英文)》 2009年 第3卷 第1期   页码 32-41 doi: 10.1007/s11709-009-0003-8

摘要: A vertical ship lift under earthquake excitation may suffer from a whipping effect due to the sudden change of building lateral stiffness at the top of the ship lift towers. This paper proposes a roof magnetorheological (MR) intelligent isolation system to prevent the seismic whipping effect on machinery structures. Theoretically, the dynamic models of MR damper and the mechanical model of ship lift was established, the inverse neural network controlling algorithm was proposed and the fundamental semi-active control equation for the Three-Gorges ship lift where the MR intelligent isolation system was installed was deduced. Experimentally, the experimental model of the ship lift was given, the vibrating table experiment of the MR intelligent isolation system controlling the whipping effect was carried out and the results of the inverse neural network control strategy and passive isolation strategy were compared. In practical aspect, the large-scale MR damper (500 kN) and a sliding support with limited stiffness were designed and fabricated. It was proven that the MR intelligent isolation system with proper control strategy can greatly reduce the seismic whipping effect on the top workshop of the ship lift and be simple and effective enough to be applied to real engineering structures.

关键词: Three-Gorges ship lift tower     whipping effect     magnetorheological (MR) intelligent isolation system     neural network     sliding steel supporting    

Aseismic smart building isolation systems under multi-level earthquake excitations: Part II, energy-dissipation

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 297-306 doi: 10.1007/s11709-015-0308-8

摘要: Based on the performance results of the previously suggested smart building isolation systems (1st companion paper), this following study verifies the control effects of the systems from the view point of energy dissipation and damage level metrics. Several different model cases of the strategically isolated multi-story building structures utilizing passive dampers and semi-active resettable devices are analyzed and the energy-based target indices are compared. Performance comparisons are conducted on statistically calculated story/structural hysteretic energy and story/structural damage demands over realistic suites of earthquake ground motion records, representing seismic excitations of specific return period probability. Again, the semi-active solutions show significant promise for applications of resettable device, offering advantages over passive systems in the consistent damage reductions. The specific results of this study include the identification of differences in the mechanisms by which smart building isolation systems remove energy, based on the differences in the devices used. Less variability is also seen for the semi-active isolation systems, indicating an increased robustness.

关键词: smart building isolation     story and structural     energy-dissipation     damage assessment    

Recent development of vibration utilization engineering

WEN Bangchun

《机械工程前沿(英文)》 2008年 第3卷 第1期   页码 1-9 doi: 10.1007/s11465-008-0017-2

摘要: The utilization of vibration and wave, which was developed during the latter half of the 20th century, is one of the most valueable technology applications and has been rapidly developing recently . Because the technique is closely associated with industry and agriculture, it can create huge social and economical benefits and provide excellent services for society. Thus, due to its necessity in industry and daily life, extensive research has been devoted to vibration utillization engineering. In this paper, vibration utilization is classified into linear or non-linear vibrations, waves, and electric-magnetic oscillations. Their phenomena, patterns, and applications in nature and society are introduced. Some research results about vibration utilization engineering are described.

关键词: utilization engineering     non-linear     vibration     vibration utillization     utillization engineering    

Application of python-based Abaqus preprocess and postprocess technique in analysis of gearbox vibration

Guilian YI, Yunkang SUI, Jiazheng DU

《机械工程前沿(英文)》 2011年 第6卷 第2期   页码 229-234 doi: 10.1007/s11465-011-0128-z

摘要:

To reduce vibration and noise, a damping layer and constraint layer are usually pasted on the inner surface of a gearbox thin shell, and their thicknesses are the main parameters in the vibration and noise reduction design. The normal acceleration of the point on the gearbox surface is the main index that can reflect the vibration and noise of that point, and the normal accelerations of different points can reflect the degree of the vibration and noise of the whole structure. The K-S function is adopted to process many points’ normal accelerations as the comprehensive index of the vibration characteristics of the whole structure, and the vibration acceleration level is adopted to measure the degree of the vibration and noise. Secondary development of the Abaqus preprocess and postprocess on the basis of the Python scripting programming automatically modifies the model parameters, submits the job, and restarts the analysis totally, which avoids the tedious work of returning to the Abaqus/CAE for modifying and resubmitting and improves the speed of the preprocess and postprocess and the computational efficiency.

关键词: Abaqus secondary development     Python language     vibration and noise reduction     K-S function     vibration acceleration level    

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

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    

Similitude design for the vibration problems of plates and shells: A review

Yunpeng ZHU, You WANG, Zhong LUO, Qingkai HAN, Deyou WANG

《机械工程前沿(英文)》 2017年 第12卷 第2期   页码 253-264 doi: 10.1007/s11465-017-0418-1

摘要:

Similitude design plays a vital role in the analysis of vibration and shock problems encountered in large engineering equipment. Similitude design, including dimensional analysis and governing equation method, is founded on the dynamic similitude theory. This study reviews the application of similitude design methods in engineering practice and summarizes the major achievements of the dynamic similitude theory in structural vibration and shock problems in different fields, including marine structures, civil engineering structures, and large power equipment. This study also reviews the dynamic similitude design methods for thin-walled and composite material plates and shells, including the most recent work published by the authors. Structure sensitivity analysis is used to evaluate the scaling factors to attain accurate distorted scaling laws. Finally, this study discusses the existing problems and the potential of the dynamic similitude theory for the analysis of vibration and shock problems of structures.

关键词: review     dynamic     similitude     vibration     model test    

双级驱动半主动隔振系统的可调反共振频率控制器 Research Articles

赵勃1,2,史维佳1,2,王丙泉1,2,谭久彬1,2

《信息与电子工程前沿(英文)》 2021年 第22卷 第10期   页码 1390-1401 doi: 10.1631/FITEE.2000373

摘要: 在半导体制造业中,被控对象的动态模型通常是在运动控制前通过扫频方法获得。然而,现有隔离器不能很好隔离扫频时惯性力(频率在0 Hz和固有频率之间)对平台基座的干扰。本文提出一种用于双级驱动半主动隔振系统的可调反共振频率控制器。双级驱动半主动隔振系统具有显著的反共振特性,在一个特定频率——即所谓反共振频率——振幅可降至接近零。本控制器的设计目的是增加一个可调的控制器反共振频率,以充分利用这种独特的反共振特性。实验结果表明了本方案的可行性,闭环传递率从0 Hz到初始反共振频率小于−15 dB。此外,在附加反共振频率附近,闭环传递率小于−30 dB,可通过改变控制器参数实现附加反共振频率在0 Hz至初始反共振频率之间的调节。当平台基座受到脉冲扰动时,使用本文提出的控制器,有效载荷扰动幅度从4 mm/s衰减至0.5 mm/s,降低87.5%。同时,通过跟踪扫频干扰,系统可实时调整反共振频率点,获得良好隔振性能。这表明双级驱动半主动隔振系统和所提控制器可应用于保证超低振动环境,特别是在半导体制造业的扫频工作中。

关键词: 半主动隔振;双级驱动;动态吸振;可调反共振频率控制器    

Multi-harmonic forced vibration and resonance of simple beams to moving vehicles

《结构与土木工程前沿(英文)》   页码 981-993 doi: 10.1007/s11709-023-0979-5

摘要: This study modeled the moving-vehicle-induced forcing excitation on a single-span prismatic bridge as a multiple frequency-multiplication harmonic load on the modal coordinates of a linear elastic simple Euler–Bernoulli beam, and investigated the forced modal oscillation and resonance behavior of this type of dynamic system. The forced modal responses consist of multiple frequency-multiplication steady-state harmonics and one damped mono-frequency complementary harmonic. The analysis revealed that a moving load induces high-harmonic forced resonance amplification when the moving speed is low. To verify the occurrence of high-harmonic forced resonance, numerical tests were conducted on single-span simple beams based on structural modeling using the finite element method (FEM) and a moving sprung-mass oscillator vehicle model. The forced resonance amplification characteristics of the fundamental mode for beam response estimation are presented with consideration to different end restraint conditions. The results reveal that the high-harmonic forced resonance may be significant for the investigated beams subjected to vehicle loads moving at specific low speeds. For the investigated single-span simple beams, the moving vehicle carriage heaving oscillation modulates the beam modal frequency, but does not induce notable variation of the modal oscillation harmonic structure for the cases that vehicle of small mass moves in low speed.

关键词: forced vibration     linear Euler beam     moving load     harmonic structure     frequency modulation     end restraints    

Analytical and numerical investigation into the longitudinal vibration of uniform nanotubes

null

《机械工程前沿(英文)》 2014年 第9卷 第2期   页码 142-149 doi: 10.1007/s11465-014-0292-z

摘要:

In recent years, prediction of the behaviors of micro and nanostructures is going to be a matter of increasing concern considering their developments and uses in various engineering fields. Since carbon nanotubes show the specific properties such as strength and special electrical behaviors, they have become the main subject in nanotechnology researches. On the grounds that the classical continuum theory cannot accurately predict the mechanical behavior of nanostructures, nonlocal elasticity theory is used to model the nanoscaled systems. In this paper, a nonlocal model for nanorods is developed, and it is used to model the carbon nanotubes with the aim of the investigating into their longitudinal vibration. Following the derivation of governing equation of nanorods and estimation of nondimensional frequencies, the effect of nonlocal parameter and the length of the nanotube on the obtained frequencies are studied. Furthermore, differential quadrature method, as a numerical solution technique, is used to study the effect of these parameters on estimated frequencies for both classical and nonlocal theories.

关键词: continuum theory     differential quadrature method     nanorod     longitudinal vibration    

Design of ultrasonic elliptical vibration cutting system for tungsten heavy alloy

《机械工程前沿(英文)》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0715-1

摘要: Nanoscale surface roughness of tungsten heavy alloy components is required in the nuclear industry and precision instruments. In this study, a high-performance ultrasonic elliptical vibration cutting (UEVC) system is developed to solve the precision machining problem of tungsten heavy alloy. A new design method of stepped bending vibration horn based on Timoshenko’s theory is first proposed, and its design process is greatly simplified. The arrangement and working principle of piezoelectric transducers on the ultrasonic vibrator using the fifth resonant mode of bending are analyzed to realize the dual-bending vibration modes. A cutting tool is installed at the end of the ultrasonic vibration unit to output the ultrasonic elliptical vibration locus, which is verified by finite element method. The vibration unit can display different three-degree-of-freedom (3-DOF) UEVC characteristics by adjusting the corresponding position of the unit and workpiece. A dual-channel ultrasonic power supply is developed to excite the ultrasonic vibration unit, which makes the UEVC system present the resonant frequency of 41 kHz and the maximum amplitude of 14.2 μm. Different microtopography and surface roughness are obtained by the cutting experiments of tungsten heavy alloy hemispherical workpiece with the UEVC system, which validates the proposed design’s technical capability and provides optimization basis for further improving the machining quality of the curved surface components of tungsten heavy alloy.

关键词: tungsten heavy alloy     ultrasonic elliptical vibration cutting     Timoshenko’s theory     resonant mode of bending     finite element method    

标题 作者 时间 类型 操作

Innovative seismic retrofitting strategy of added stories isolation system

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

期刊论文

H control in the frequency domain for a semi-active floor isolation system

Yundong SHI, Tracy C BECKER, Masahiro KURATA, Masayoshi NAKASHIMA

期刊论文

Vibration characteristics and machining performance of a novel perforated ultrasonic vibration platform

期刊论文

Isolation and application of predatory

Ran Yu, Shiwen Zhang, Zhoukai Chen, Chuanyang Li

期刊论文

Novel polymorphic EST-based microsatellite marker isolation and characterization from

Manosh Kumar BISWAS,Peng CHEN,Mohamed Hamdy AMAR,Xiuxin DENG

期刊论文

seismic response control on top of Three-Gorges ship lift towers using magnetorheological intelligent isolation

Weilian QU, Jianwei TU

期刊论文

Aseismic smart building isolation systems under multi-level earthquake excitations: Part II, energy-dissipation

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

期刊论文

Recent development of vibration utilization engineering

WEN Bangchun

期刊论文

Application of python-based Abaqus preprocess and postprocess technique in analysis of gearbox vibration

Guilian YI, Yunkang SUI, Jiazheng DU

期刊论文

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

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

期刊论文

Similitude design for the vibration problems of plates and shells: A review

Yunpeng ZHU, You WANG, Zhong LUO, Qingkai HAN, Deyou WANG

期刊论文

双级驱动半主动隔振系统的可调反共振频率控制器

赵勃1,2,史维佳1,2,王丙泉1,2,谭久彬1,2

期刊论文

Multi-harmonic forced vibration and resonance of simple beams to moving vehicles

期刊论文

Analytical and numerical investigation into the longitudinal vibration of uniform nanotubes

null

期刊论文

Design of ultrasonic elliptical vibration cutting system for tungsten heavy alloy

期刊论文