Extreme Responses of An Integrated System with A Semi-Submersible Wind Turbine and Four Torus-Shaped Wave Energy Converters in Different Survival Modes

Offshore wind power is a kind of important clean renewable energy and has attracted increasing attention due to the rapid consumption of non-renewable energy.To reduce the high cost of energy,a possible try is to utilize the combination of wind and wave energy considering their natural correlation.A combined concept consisting of a semi-submersible wind turbine and four torus-shaped wave energy converters was proposed and numerically studied under normal operating conditions.However,the dynamic behavior of the integrated system under extreme sea conditions has not been studied yet.In the present work,extreme responses of the integrated system under two different survival modes are evaluated.Fully coupled time-domain simulations with consideration of interactions between the semi-submersible wind turbine and the torus-shaped wave energy converters are performed to investigate dynamic responses of the integrated system,including mooring tensions,tower bending moments,end stop forces,and contact forces at the Column-Torus interface.It is found that the addition of four tori will reduce the mean motions of the yaw,pitch and surge.When the tori are locked at the still water line,the whole integrated system is more suitable for the survival modes.

Combined hybrid energy storage system and transmission grid model for peak shaving based on time series operation simulation

This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure of power systems under the integration of renewable energy. First, a linear model for the optimal operation of the HESS is established, which considers the different power-efficiency characteristics of the pumped storage system, electrochemical storage system, and a new type of liquid compressed air energy storage. Second, a TSOS simulation model for peak shaving is built to maximize the power entering the grid from the wind farms and HESS. Based on the proposed model, this study considers the transmission capacity of a TG. By adding the power-flow constraints of the TG, a TSOS-based HESS and TG combination model for peak shaving is established. Finally, the improved IEEE-39 and IEEE-118 bus systems were considered as examples to verify the effectiveness and feasibility of the proposed model.

Electronic Structure Investigation of 12442 Iron-Based Superconductors Based on Block-Layer Model

Superconducting transition temperature(Tc),as a crucial parameter,exploring its relationship with various macroscopic and microscopic factors helps to understand the mechanism of high-temperature superconductivity from multiple perspectives,aiding in a multidimensional comprehension of high-temperature superconductivity mechanisms.Drawing inspiration from the block-layer structure models of cuprate superconductors,we computationally investigated the interlayer interaction energies in the 12442-type iron-based superconducting materials AkCa_(2)Fe_(4)As_(4)F_(2)(Ak=K,Rb,Cs)systems based on the block-layer model and explored their relationship with Tc.We observed that an increase in interlayer combinative energy leads to a decrease in Tc,while conversely,a decrease in interlayer combination energy results in an increase in Tc.Further,we found that the contribution of the Fe 3d band structure,especially the 3dz2 orbital,to charge transfer is significant.

Comparative numerical and experimental study of two combined wind and wave energy concepts

With a successful and rapid development of offshore wind industry and increased research activities on wave energy conversion in recent years,there is an interest in investigating the technological and economic feasibility of combining offshore wind turbines(WTs)with wave energy converters(WECs).In the EU FP7 MARINA Platform project,three floating combined concepts,namely the spar torus combination(STC),the semi-submersible flap combination(SFC)and the oscillating water column(OWC)array with a wind turbine,were selected and studied in detail by numerical and experimental methods.This paper summarizes the numerical modeling and analysis of the two concepts:STC and SFC,the model tests at a 1:50 scale under simultaneous wave and wind excitation,as well as the comparison between the numerical and experimental results.Both operational and survival wind and wave conditions were considered.The numerical analysis was based on a time-domain global model using potential flow theory for hydrodynamics and blade element momentum theory(for SFC)or simplified thrust force model(for STC)for aerodynamics.Different techniques for model testing of combined wind and wave concepts were discussed with focus on modeling of wind turbines by disk or redesigned small-scale rotor and modeling of power take-off(PTO)system for wave energy conversion by pneumatic damper or hydraulic rotary damper.In order to reduce the uncertainty due to scaling,the numerical analysis was performed at model scale and both the numerical and experimental results were then up-scaled to full scale for comparison.The comparison shows that the current numerical model can well predict the responses(motions,PTO forces,power production)of the combined concepts for most of the cases.However,the linear hydrodynamic model is not adequate for the STC concept in extreme wave conditions with the torus fixed to the spar at the mean water level for which the wave slamming on the torus occurs and this requires further investigation.Moreover,based on a preliminary comparison of the displacement,the PTO system as well as the wind and wave power production,the STC concept will have a lower cost of energy as compared to the SFC concept.However,the cost of energy of either the STC or the SFC concept is higher than that of a pure floating wind turbine with the same floater.

Effect of Copper Content on the Direct Process of Organosilane Synthesis from Silicon and Methyl Chloride

The effect of copper concentration on the performance of the catalytic reaction between silicon and methyl chloride was investigated using online gas chromatogram. The catalyst concentration greatly influences various aspects of the direct organosilane synthesis process, including the reaction rate, the selec- tivity, and the silicon conversion. The reaction activity and the silicon conversion increase as the catalyst concentration increases. However, the reaction selectivity decreases for the catalyst concentrations more .than 9 wt.%. The cross-sections of deactivated contact mass particles were observed by optical microscopy and analyzed by scanning electron microscope combined with energy dispersive X-ray detector （SEM-EDX） The observations showed that a textured substance formed on the original flat surface of the silicon particles after deactivation with copper only in a shallow surface layer of the contact mass. This indicates that the copper diffusion is the rate limiting step which causes the reaction deactivation.