Response Of Combined System Research Articles

Dynamic response and power performance of a combined semi-submersible floating wind turbine and point absorber wave energy converter array

With the global demand for renewable energy rising, offshore renewable energy development has gained more attention. The combination of wind and wave energy is a new trend. Ensuring stability in combined systems is crucial for efficiency of absorbing energy. A novel combined wind and wave energy system with a semi-submersible floating wind turbine (FWT) and an array of six torus-shaped point absorber wave energy converters (WECs) is proposed. The dynamic response of combined system is investigated using 3D potential flow theory by comparing to the original system. The effects of power take-off (PTO) damping, WEC float shape and seasonal variation on the dynamic response and power performance of combined system are studied. The results show that the addition of WEC array improves the stability and power production of combined system. Meanwhile, the total power of combined system is approximately 2.5%–6.5 % higher than that of original system. PTO damping mainly affects the heave motion of combined system. As PTO damping increases, the first peak of mean power of WEC array shifts towards the long period, while the second peak of that shifts towards the short period. The conical-bottom WEC generates the most power compared to the flat-bottom WEC, hemispherical-bottom WEC and concave-bottom WEC. The combined system generates the most power in winter, and the total annual electricity output can be up to 2.99 × 104 MWh.

Seismic Performance of Reinforced Concrete Buildings with Different Lateral Load

Shear wall, steel bracing and combined system are the most commonly used lateral-load resisting technique for high-rise buildings. Shear walls have very high in-plane strength and stiffness, which can be used simultaneously for resisting large horizontal and gravity loads. The aim of this study is to examine how well reinforced concrete buildings withstand seismic activity using various systems for resisting lateral loads. In this study, a reinforced concrete building with 12 floors (G+12) and 5 X 5 bays is selected, and various lateral load resisting frame systems are applied in different positions. These are shear wall, bracings, shear wall-bracings combinations (Combined) at five different locations/patterns i.e., at outer corners (Type- I), center of outer sides (Type- II), middle corners (Type- III), center of middle sides (Type- IV), and inner core and middle sides (Type- V) respectively. A total of sixteen models are created for this study, with one being a bare frame and the other fifteen consisting of three types of lateral load resisting systems arranged in five different configurations each. With the assistance of ETABS all models are analyzed by Equivalent Static Analysis and Response Spectrum Analysis. The performance of building is evaluated on the basis of following parameters- maximum storey displacement, maximum storey drift and storey shear. At last the results are compared for different models. Among the three systems, the shear wall system exhibits the least displacement and the highest stiffness. Response of combined system is better than that of bracing system. Overall, the Type II shear wall model is more earthquake-resistant and structurally efficient than the other fifteen models. Key Words: Equivalent Static Analysis, Response Spectrum Analysis, Maximum storey displacement, Maximum storey drift, Storey shear

Modifications on F 2 MC tubes as passive tunable vibration absorbers

This paper presents new parameters for damping improvement in F2MC tubes performance as tunable vibration absorbers. They offer very good performance with environments having susceptibility to high frequency vibration noise. This study highlights the behavior of changing some parameters of F2MC tubes which never have been studied before. These parameters include thickness ratio between each two respective layers and fluid type that the tubes are filled with. In this paper the beam governing equations with the tube's stress analyses equations are solved for finding the combined system's response by MATLAB® software function solvers. To ensure accuracy of modifications, validations have been proposed by performing illustrative examples and comparing the results with the existing data available in literature. The results showed improvements of F2MC tubes performance 20% over previous studies achievements by studying the thickness ratio, and another 12.82% can be added by using glycerin instead of water under the same conditions. Finally, the reduction of 34.34 dB in first mode amplitude of vibration was achieved in the beam's frequency response function plot.

Can tailored non-linearity of hierarchical structures inform future material development?

An analytical investigation into the non-linear elastic response of helical lattice structures coupled with an elastic medium is presented. Novel composite templates are then obtained to produce bespoke material characteristics by exploiting tuned hierarchy. System behaviour is approximated as a combination of three non-linear “springs”, representing the helical lattice, and the axial and circumferential components of the elastic medium via an energy based approach. Non-dimensional parameters governing each component’s non-linear load–displacement behaviour are identified, demonstrating tailoring potential. Further tunable parameters that govern the combined system response, involving form factor, geometric and stiffness ratios are identified. In particular, pseudo-ductile responses are observed. The feasible region of pseudo-ductility, as determined by these non-dimensional parameters, is obtained, allowing discussion of viable materials and geometries. Finally, load–displacement behaviour is utilised to obtain indicative effective stress–strain curves, thus showing promise as a model for future material development.

Single-electron double quantum dot dipole-coupled to a single photonic mode

We have realized a hybrid solid-state quantum device in which a single-electron semiconductor double quantum dot is dipole coupled to a superconducting microwave frequency transmission line resonator. The dipolar interaction between the two entities manifests itself via dispersive and dissipative effects observed as frequency shifts and linewidth broadenings of the photonic mode respectively. A Jaynes-Cummings Hamiltonian master equation calculation is used to model the combined system response and allows for determining both the coherence properties of the double quantum dot and its interdot tunnel coupling with high accuracy. The value and uncertainty of the tunnel coupling extracted from the microwave read-out technique are compared to a standard quantum point contact charge detection analysis. The two techniques are found to be consistent with a superior precision for the microwave experiment when tunneling rates approach the resonator eigenfrequency. Decoherence properties of the double dot are further investigated as a function of the number of electrons inside the dots. They are found to be similar in the single-electron and many-electron regimes suggesting that the density of the confinement energy spectrum plays a minor role in the decoherence rate of the system under investigation.

Study on Chromium (VI) Reduction Kinetics by Pseudomonas aeruginosa Using a Combined System of Acoustic Wave Impedance Analyzer and UV-Vis Spectrophotometer

A novel system combining acoustic wave impedance (AWI) analyzer with UV-vis spectrophotometer was developed for the study of chromium (VI) reduction kinetics by Pseudomonas aeruginosa. AWI gave information about the growth of Pseudomonas aeruginosa, and UV-vis spectrophotometer gave information about the concentration of chromium (VI) simultaneously. A combined system response model, for chromium (VI) reduction kinetics at lower initial chromium (VI) concentrations, was derived and proved based on the novel system. Taking into account the effect of bacterial growth on chromium (VI) reduction, the new model successfully simulated chromium (VI) bioremediation process. By fitting chromium (VI) reduction data toward the derived model, the kinetic parameters related to the process were obtained. When the concentration of peptone was 10 g L(-1), the half-velocity reduction rate constant K (C) and the maximum specific chromium (VI) reduction rate constant nu(max) were 0.7682 mg chromium (VI) L(-1) and 2.5814 x 10(-12) mg chromium (VI) cells(-1) h(-1), respectively. It was found that the combined system can provide real-time, reliable, and two-dimensional kinetic information, and can be applied to study other biological processes.

The influence of substructure modeling on the structural-acoustic response of a plate system.

Changes in the vibro-acoustic response of a fluid-loaded plate due to variations in some of the modeling details associated with an attached substructure are examined. The attached substructure consists of a smaller plate supported by springs along each edge. To examine the important modeling issues, three studies are performed. In the first study, discrete changes in the system response due to discrete changes in the size of the region over which the spring elasticity is distributed are examined. In the second study, substructure modeling issues are examined by varying the number of degrees-of-freedom included in the substructure model. Finally, sensitivity relationships that express changes in the system response to changes in the scale of the spring elements are developed. These relationships are used to examine changes in the system response due to small variations in the scale of the distributed elasticity. Both the combined system response and acoustic radiation are computed using the Acoustic Surface Variational Principle and Hamilton's Principle. For the example cases considered, it is shown that details associated with the scale of the spring are only important for frequencies near or below the resonances of the isolated subsystem. Furthermore, only the dynamics of the substructure including rigid-body type motions are important.

The influence of substructure modeling on the predicted vibroacoustic response of a fluid-loaded plate system

When predicting the vibroacoustic behavior of complex systems, one must decide how much effort to spend on modeling the features with dimensions smaller than those of the primary structure. To investigate these issues, this work examines changes in the vibroacoustic response of a semi-infinite fluid-loaded plate due to variations in modeling details associated with an attached substructure. The substructure consists of a smaller plate supported by springs along each edge. To examine the impact of spring scales, the manner in which the elasticity is distributed over the main plate is varied. Substructure modeling issues are examined by varying the number of degrees-of-freedom allowed in the substructure model. Both the combined system response and acoustic radiation from the main plate are computed using the Acoustic Surface Variational Principle and Hamilton’s Principle. Furthermore, sensitivity relationships that express changes in the system response to changes in the scale of the spring elements are presented. For the cases considered, it is shown that details associated with the scale of the spring element are only important for frequencies near or below the resonances of the isolated subsystem. Furthermore, only the dynamics of the substructure that includes rigid-body-type motions is important. [Work supported by Georgia Tech.]