The dynamic characterization is important in making accurate predictions of the seismic response of the hybrid structures dominated by different damping mechanisms. Different damping characteristics arise from the construction of hybrid structure with different materials: steel for the upper part; reinforced concrete for the lower main part and interaction with supporting soil. The process of modeling damping matrices and experimental verification is challenging because damping cannot be determined via static tests as can mass and stiffness. The assumption of classical damping is not appropriate if the system to be analyzed consists of two or more parts with significantly different levels of damping. The dynamic response of structures is critically determined by the damping mechanisms, and its value is very important for the design and analysis of vibrating structures. A numerical algorithm capable of evaluating the equivalent modal damping ratio from structural components is desirable for improving seismic design. Two approaches are considered to explore the dynamic response of hybrid tower of cable-stayed bridges: The first approach makes use of a simplified model of 2 coupled lumped masses to investigate the effects of subsystems different damping, mass ratio, frequency ratio on dynamic characteristics and equivalent modal damping; the second approach employs a detailed numerical step-by step integration procedure.

This work presents the design and the measured performance of a 8 Gb/s transimpedance amplifier (TIA) fabricated in a 90 nm CMOS technology. The introduced TIA uses an inverter input stage followed by two common-source stages with a 1.5 kΩ feedback resistor. The TIA is followed by a single-ended to differential converter stage, a differential amplifier and a 50 Ω differential output driver to provide an interface to the measurement setup. The optical receiver shows a measured optical sensitivity of −18.3 dBm for a bit error rate = 10−9. A gain control circuitry is integrated with the TIA to increase its input photo-current dynamic range (DR) to 32 dB. The TIA has an input photo-current range from 12 to 500 μA without overloading. The stability is guaranteed over the whole DR. The optical receiver achieves a transimpedance gain of 72 dBΩ and 6 GHz bandwidth with 0.3 pF total input capacitance for the photodiode and input PAD. The TIA occupies 0.0036 mm2 whereas the complete optical receiver occupies a chip area of 0.46 mm2. The power consumption of the TIA is only 12 mW from a 1.2 V single supply voltage. The complete chip dissipates 60 mW where a 1.6 V supply is used for the output stages.

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The effect of soil-pile separation is studied with respect to the performance of a laterally loaded pile group. Full-scale tests, which consist of a combination of a single and a 3× 5 group pile under static and dynamic lateral loads, present a unique opportunity and allow a rigorous study without arbitrary parameter back-fitting. The coupled soil-pile system is idealized through two-dimensional finite elements with soil models idealized by a hyperbolic- type multiple shear mechanism. Nonlinear spring elements are used to idealize the soil- ..

The objective of this paper is to clarify the role of thermophoresis in laminar natural convection in a Rayleigh–Benard cell filled with a water-based nanofluid and to study its relative importance compared to other effects, in an attempt to correct the present confusing interpretation of the magnitude of the thermophoresis coefficient in nanofluids. The major forces are introduced and the transport equations are solved using a two-phase lattice Boltzmann method (LBM) for a laminar flow with Ra numbers up to 106 with various particle loadings (particle volume fractions). The results indicate an increase in the average Nu number with an increase in the Ra number and particle loading. An increase in the Nu number for a 10% particle loading at Ra = 106 is less than 20%. When thermophoresis effect is taken into consideration, an increase in the Nu number is predicted, which is about 10%. Therefore, it is concluded that using a nanofluid in bottom-heated laminar natural convection results in a considerable increase in heat transfer rate and thermophoresis force is a significant contributor to heat transfer augmentation, particularly for high Ra numbers (Ra ∼ 106 and higher). It is observed that at low Ra numbers (weak convective flows), the nanofluid behaves homogenously, but at higher Ra numbers, it starts to behave heterogeneously.

The objective of this paper is to clarify the role of thermophoresis in laminar natural convection in a Rayleigh–Benard cell filled with a water-based nanofluid and to study its relative importance compared to other effects, in an attempt to correct the present confusing interpretation of the magnitude of the thermophoresis coefficient in nanofluids. The major forces are introduced and the transport equations are solved using a two-phase lattice Boltzmann method (LBM) for a laminar flow with Ra numbers up to 106 with various particle loadings (particle volume fractions). The results indicate an increase in the average Nu number with an increase in the Ra number and particle loading. An increase in the Nu number for a 10% particle loading at Ra = 106 is less than 20%. When thermophoresis effect is taken into consideration, an increase in the Nu number is predicted, which is about 10%. Therefore, it is concluded that using a nanofluid in bottom-heated laminar natural convection results in a considerable increase in heat transfer rate and thermophoresis force is a significant contributor to heat transfer augmentation, particularly for high Ra numbers (Ra ∼ 106 and higher). It is observed that at low Ra numbers (weak convective flows), the nanofluid behaves homogenously, but at higher Ra numbers, it starts to behave heterogeneously.

Recent studies show that the effects of SSI may be detrimental to the seismic response of structure and neglecting SSI in analysis may lead to un-conservative design. Despite this, the conventional design procedure usually involves assumption of fixity at the base of foundation neglecting the flexibility of the foundation, the compressibility of soil mass and consequently the effect of foundation settlement on further redistribution of bending moment and shear force demands. The effects of SSI are analyzed for typical multistory building resting on raft foundation. Three methods of analysis are used for seismic demands evaluation of the target moment resistant frame buildings: equivalent static load (ESL); response spectrum (RS) methods and nonlinear time history (TH) analysis with suit of nine time history records. Three-dimensional FEM model is constructed to analyze the effects of different soil conditions and number of stories on the vibration characteristics and seismic response demands of building structures. Numerical results obtained using soil structure interaction model conditions are compared to those corresponding to fixed-base support conditions. The peak responses of story shear, story moment, story displacement, story drift, moments at beam ends, as well as force of inner columns are analyzed.