Wind Power Assessment Based on a WRF Wind Simulation with Developed Power Curve Modeling Methods

The accurate assessment of wind power potential requires not only the detailed knowledge of the local wind resource but also an equivalent power curve with good effect for a local wind farm. Although the probability distribution functions (pdfs) of the wind speed are commonly used, their seemingly good performance for distribution may not always translate into an accurate assessment of power generation. This paper contributes to the development of wind power assessment based on the wind speed simulation of weather research and forecasting (WRF) and two improved power curve modeling methods. These approaches are improvements on the power curve modeling that is originally fitted by the single layer feed-forward neural network (SLFN) in this paper; in addition, a data quality check and outlier detection technique and the directional curve modeling method are adopted to effectively enhance the original model performance. The proposed two methods, named WRF-SLFN-OD and WRF-SLFN-WD, are able to avoid the interference from abnormal output and the directional effect of local wind speed during the power curve modeling process. The data examined are from three stations in northern China; the simulation indicates that the two developed methods have strong abilities to provide a more accurate assessment of the wind power potential compared with the original methods

trans-3,3′,4,5′-Tetra­meth­oxy­stilbene

The title compound, C18H20O4, was synthesized by a Wittig–Horner reaction of diethyl 3,4-dimeth­oxy­benzyl­phosphate and 3,5-dimeth­oxy­benzaldehyde. In the crystal, the dihedral angle between the two aromatic rings is 2.47 (12)°. All the meth­oxy groups are almost coplanar with the aromatic ring to which they are attached [C—C—O—C torsion angles = −2.8 (3), −5.2 (4), −176.3 (2) and −178.0 (2)°]

Extraction of Plumes in Turbulent Thermal Convection

We present a scheme to extract information about plumes, a prominent coherent structure in turbulent thermal convection, from simultaneous local velocity and temperature measurements. Using this scheme, we study the temperature dependence of the plume velocity and understand the results using the equations of motion. We further obtain the average local heat flux in the vertical direction at the cell center. Our result shows that heat is not mainly transported through the central region but instead through the regions near the sidewalls of the convection cell.Comment: 4 pages, 4 figures, submitted to Physical Review Letter