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Influence of fluid-structure interaction on vortex induced vibration and lock-in phenomena in long span bridges

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Frontiers of Structural and Civil engineering 2016年第4期10卷 363-384页

作者： nazim Abdui NARImAN Institute of Structural mechanics Faculty of Civil Engineering Bauhaus University Weimar Weimar 99423 Germany

In this paper, deck models of a cable stayed bridge are generated in ABAQUS-finite element program once using only CFD model （one-way fluid-structure interaction） and another by using both the CFD model and the CSD model together （two-way fluid-structure interaction） in a co-simulation. Shedding frequencies for the associated wind velocities in the lock-in region are calculated in both approaches. The results are validated with Simiu and Scanlan results. The lift and drag coefficients are determined for the two approaches and the latter results are validated with the flat plate theory results by munson and coauthors. A decrease in the critical wind velocity and the shedding frequencies considering two-way approach was determined compared to those obtained in the one-way approach. The results of the lift and drag forces in the two-way approach showed appreciable decrease in their values. It was concluded that the two-way approach predicts earlier vortex induced vibration for lower critical wind velocities and lock-in phenomena will appear at lower natural frequencies of the long span bridges. This helps the designers to efficiently plan and consider for the design and safety of the long span bridge against this type of vibration.

关键词： vortex-induced vibration fluid-structure interaction Strouhal number lock-in kinetic energy

DeFPOS Hα observations of the W80 Complex

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Research in Astronomy and Astrophysics 2013年第5期13卷 547-556页

作者： nazim Aksaker Vocational School of Technical Sciences University of C ukurova Research and Application of Space Sciences and Solar energy Center (UZAYmeR) University of Cukurova

We present Hα emission line measurements of the W80 nebula complex. A total of 26 regions have been observed inside the nebula with the Dual etalon Fabry- Perot Optical Spectrometer system at the f/48 Coud6 focus of the 150 cm RTT150 telescope located at TUBITAK National Observatory in Antalya, Turkey. The inten- sities, local standard of rest velocities, heliocentric radial velocities and linewidths for full width at half maximum of the Hα emission lines have been determined from these observations. They lie in the range of 259 to 1159 Rayleigh （R; 1R = 106/47r pho- tons cm-2 sr-1 S-1 = 2.41 × 10-7 erg cm-2 sr-1 S-1 at Ha）, 4 to 12 km s-1, -3 to -11 km s-1 and 44 to 55 km s-i, respectively. The radial velocity measurements show that there are several maxima and minima inside W80. The new results confirm findings in the literature that the complex seems to be rather uniform in terms of radial velocity and no turbulent motion is seen inside the complex. The average value of the calculated emission measure for the region is 3.1 pc cm-6.

关键词： instrumentation: interferometers -- ISm: H II regions -- techniques:radial velocities -- techniques: interferometric

A novel structural modification to eliminate the early coupling between bending and torsional mode shapes in a cable stayed bridge

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Frontiers of Structural and Civil engineering 2017年第2期11卷 131-142页

作者： nazim Abdul NARImAN Institute of Structural mechanics Faculty of Civil Engineering Bauhaus University Weimar Weimar 99423 Germany

In this paper, a novel structural modification approach has been adopted to eliminate the early coupling between the bending and torsional mode shapes of vibrations for a cable stayed bridge model generated using ABAQUS software. Two lateral steel beams are added to the middle span of the structure. Frequency analysis is dedicated to obtain the natural frequencies of the first eight mode shapes of vibrations before and after the structural modification approach. Numerical simulations of wind excitations are conducted for the 3D model of the cable stayed bridge with duration of 30 s supporting on real data of a strong wind from the literature. Both vertical and torsional displacements are calculated at the mid span of the deck to analyze both the bending and the torsional stiffness of the system before and after the structural modification. The results of the frequency analysis after applying lateral steel beams declared a safer structure against vertical and torsional vibrations and rarely expected flutter wind speed. Furthermore, the coupling between the vertical and torsional mode shapes has been removed to larger natural frequencies magnitudes with a high factor of safety. The novel structural approach manifested great efficiency in increasing vertical and torsional stiffness of the structure.

关键词： aeroelastic instability structural damping flutter wind speed bending stiffness torsional stiffness

Thermal fluid-structure interaction and coupled thermal-stress analysis in a cable stayed bridge exposed to fire

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Frontiers of Structural and Civil engineering 2018年第4期12卷 609-628页

作者： nazim Abdul NARImAN Institute of Structural mechanics Faculty of Civil EngineeringBauhaus Universitat WeimarMarienstrasse 1599423WeimarGermany

In this paper, thermal fluid structure-interaction (TFSI) and coupled thermal-stress analysis are utilized to identify the effects of transient and steady-state heat-transfer on the vortex induced vibration and fatigue of a segmental bridge deck due to fire incidents. Numerical simulations of TFSI models of the deck are dedicated to calculate the lift and drag forces in addition to determining the lock-in regions once using fluid-structure interaction (FSI) models and another using TFSI models. Vorticity and thermal convection fields of three fire scenarios are simulated and analyzed. Simiu and Scanlan benchmark is used to validate the TFSI models, where a good agreement was manifested between the two results. extended finite element method (XFem) is adopted to create 3D models of the cable stayed bridge to simulate the fatigue of the deck considering three fire scenarios. Choi and Shin benchmark is used to validate the damaged models of the deck in which a good coincide was seen between them. The results revealed that TFSI models and coupled thermal-stress models are significant in detecting earlier vortex induced vibration and lock-in regions in addition to predicting damages and fatigue of the deck due to fire incidents.

关键词： fire scenario transient heat transfer TFSI model coupled thermal-stress XFem

Control efficiency optimization and Sobol＇s sensitivity indices of mTmDs design parameters for buffeting and flutter vibrations in a cable stayed bridge

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Frontiers of Structural and Civil engineering 2017年第1期11卷 66-89页

作者： nazim Abdul NARImAN Institute of Structural mechanics School of Civil Engineering Bauhaus University Weimar Weimar 99423 Germany

This paper studies optimization of three design parameters （mass ratio, frequency ratio and damping ratio） of multiple tuned mass dampers mTmDs that are applied in a cable stayed bridge excited by a strong wind using minimax optimization technique. ABAQUS finite element program is utilized to run numerical simulations with the support of mATLAB codes and Fast Fourier Transform FFT technique. The optimum values of these three parameters are validated with two benchmarks from the literature, first with Wang and coauthors and then with Lin and coauthors. The validation procedure detected a good agreement between the results. Box-Behnken experimental method is dedicated to formulate the surrogate models to represent the control efficiency of the vertical and torsional vibrations. Sobol＇s sensitivity indices are calculated for the design parameters in addition to their interaction orders. The optimization results revealed better performance of the mTmDs in controlling the vertical and the torsional vibrations for higher mode shapes. Furthermore, the calculated rational effects of each design parameter facilitate to increase the control efficiency of the mTmDs in conjunction with the support of the surrogate models.

关键词： mTmDs power spectral density fast Fourier transform minimax optimization technique Sobol's sensitivityindices Box-Behnken method

Neurogenesis dynamics in the olfactory bulb:deciphering circuitry organization, function, and adaptive plasticity

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Neural Regeneration Research 2025年第6期20卷 1565-1581页

作者： moawiah m.Naffaa Department of Psychology and Neuroscience Duke UniversityDurhamNCUSA Department of Cell Biology Duke University School of MedicineDurhamNCUSA

Adult neurogenesis persists after birth in the subventricular zone, with new neurons migrating to the granule cell layer and glomerular layers of the olfactory bulb, where they integrate into existing circuitry as inhibitory interneurons. The generation of these new neurons in the olfactory bulb supports both structural and functional plasticity, aiding in circuit remodeling triggered by memory and learning processes. However, the presence of these neurons, coupled with the cellular diversity within the olfactory bulb, presents an ongoing challenge in understanding its network organization and function. moreover,the continuous integration of new neurons in the olfactory bulb plays a pivotal role in regulating olfactory information processing. This adaptive process responds to changes in epithelial composition and contributes to the formation of olfactory memories by modulating cellular connectivity within the olfactory bulb and interacting intricately with higher-order brain regions. The role of adult neurogenesis in olfactory bulb functions remains a topic of debate. Nevertheless, the functionality of the olfactory bulb is intricately linked to the organization of granule cells around mitral and tufted cells. This organizational pattern significantly impacts output, network behavior, and synaptic plasticity, which are crucial for olfactory perception and memory. Additionally, this organization is further shaped by axon terminals originating from cortical and subcortical regions. Despite the crucial role of olfactory bulb in brain functions and behaviors related to olfaction, these complex and highly interconnected processes have not been comprehensively studied as a whole. Therefore, this manuscript aims to discuss our current understanding and explore how neural plasticity and olfactory neurogenesis contribute to enhancing the adaptability of the olfactory system. These mechanisms are thought to support olfactory learning and memory, potentially through increased

关键词： network adaptability neurogenesis neuronal communication olfactory bulb olfactory learning olfactory memory synaptic plasticity

Uncertainty quantification of stability and damage detection parameters of coupled hydrodynamic-ground motion in concrete gravity dams

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Frontiers of Structural and Civil engineering 2019年第2期13卷 303-323页

作者： nazim Abdul NARImAN Tom LAHmeR Pevman KARAmPOUR Institute of Structural mechanics Faculty of Civil EngineeringBauh aus Universitat Weimar99423 WeimarGermany Department of mechanical engineering Faculty of EngineeringArak UniversityArak 38156-8-8849Iran

In this paper, models of the global system of the Koyna dam have been created using ABAQUS software considering the dam-reservoir-fbundation interaction. Non coupled models and the coupled models were compared regarding the horizontal displacement of the dam crest and the differential settlement of the dam base in clay foundation. meta models were constructed and uncertainty quantification process was adopted by the support of Sobol's sensitivity in dices considering five un certain parameters by exploiting Box-Behnken experimental method. The non coupled models results determined overestimated predicted stability and damage detection in the dam. The rational effects of the reservoir height were very sensitive in the variation of the horizontal displacement of the dam crest with a small interaction effect with the beta viscous damping coefficient of the clay fbundation. The modulus of elasticity of the clay foundation was the decisive parameter regarding the variation of the differential settlement of the dam base. The XFem approach has been used for damage detection in relation with both minimum and maximum values of each uncertain parameter. Finally the effects of clay and rock foundations were determined regarding the resistance against the propagation of cracks in the dam, where the rock fbundation was the best.

关键词： massed foundation hydrodynamic pressure Box-Behnken method meta model Sobol's sensitivity indices

Biofilter:a promising tool for mitigating methane emission from manure storage

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Journal of Arid Land 2011年第1期3卷 61-70页

作者： nazim CICeK Danny mANN Department of Biosystems engineering University of Manitoba

Liquid manure storage may contribute to methane （CH4） emission and this emission can be greatly reduced if appropriate management practices are applied. Biofiltration has been used in other fields for mitigating greenhouse gas （GHG） emission （e.g., landfill） and shown promise for mitigation OH4 emis- sion from liquid manure storage. It has been reported that biofilter was capable of reducing 80% of CH4 emissions from manure storage. The OH4 removal efficiency is influenced by many factors, including OH4 and 02 concentrations, temperature, moisture, composition of the filter bed, nutrient, and empty bed resi- dency time （eBRT）. Biological conversion of methane of a biofilter is a slow process due to the low water solubility of methane. The residence times （eBRT） between 5 min and 5 h have been used, whereas a typical eBRT of 25 s is used for common biofilter applications. Temperature at which methanotrophic bac- teria are active ranges from 10℃ to 45℃. The maximum activity is found at around 30℃. The optimal filter bed water content depends on both the gas flow rate and the type of filter bed （soil, compost, etc.） and ranges from 30%-70% of the water holding capacity. Compost is the best material for filter bed. The optimal pH for methanotrophic bacteria is neutral to slightly acidic. Copper and nitrogen compounds especially nitrate are important nutrients to methanotrophic bacteria but their optimal concentrations have not been founded. Phosphorus and other elements such as potassium and manganese are reported to affect the performance of methanotrophic bacteria but need further confirmation.

关键词： biofilter greenhouse gas methane manure storage

mitochondria–cGAS–STING axis is a potential therapeutic target for senescence-dependent inflammaging-associated neurodegeneration

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Neural Regeneration Research 2025年第3期20卷 805-807页

作者： Josém.Izquierdo Centro de Biología molecular Severo Ochoa(CBm) Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid(CSIC-UAM)MadridSpain

The word “senescence” comes from the Latin senescens, meaning “to begin to age”, and is characterized by a long-lasting but reversible block in proliferation, resulting from stress-induced cell cycle arrest of pre... 详细信息

关键词： Latin potential lasting