Forsted Surface Case For Mac
Apple's granted patent covers a new vision for a future iMac/desktop PC made with a glass housing that includes a continuous surface defined by the upper portion, the lower portion, and the transition portion.
Forsted Surface Case For Mac
Apple clarifies that the glass housing could be made with materials that are transparent, coated, painted, or otherwise treated to produce a non-transparent (e.g., opaque) component; in such cases the material may still be referred to as transparent, even though the material may be part of an opaque component. Translucent components may be formed by producing a textured or frosted surface on an otherwise transparent material (e.g., clear glass). Translucent materials may also be used, such as translucent polymers, translucent ceramics, or the like.
The housing member may have properties that enable the diverse input and output functions. For example, the housing member (e.g., the optically transmissive member) may be strong and may have a high resistance to scratching, and may provide a surface finish having a superior appearance and/or tactile feel as compared with other materials or components.
In various embodiments, the housing member may include recesses, protrusions, borders, or other physical features on its exterior surface that define and/or delineate distinct key regions #459 and that can be felt by a user when typing on or otherwise touching the input area.
Raised key regions may provide a more familiar-feeling keyboard surface to users, as the individual key regions may have a similar shape and feel to conventional movable keys. Moreover, a user may be able to type faster and with fewer errors because they can feel the borders and boundaries of each key region and do not need to look at the keyboard to align their fingers with the keys. The ability to feel distinct key regions may also help prevent a user's hands from unintentionally drifting out of position during typing.
Gold PEI with the frosted surface is of strong high-temperature stability, flame retardant, heat resistance, high strength, wear-resistance, and good printing stability. No deformation at 200C. Genuine PEI powder coating is of heat resistance. Hardened steel spring plated is resistant to 200C and has no deformation. Strong magnetic force; Easy removal; Strong adhesion when printing. PC belongs to the soft magnet, with flame-retardant, wear-resistant, oxidation-resistant, low forming shrinkage, and heat resistance without demagnetization. There is a good combination of hot-melt material and the printing layer, which reduces the deformation caused by shrinkage and avoids warping.
The actuator line (AL) is a lifting line (LL) representation of aerodynamic surfaces in computational fluid dynamics (CFD) applications. The AL blade forces are computed from 2D airfoil polars and the CFD velocity vector extracted at the line position, as the self-induction at the very centre of the bound vortex should, following vortex theory, be nil. Yet, this is not the case in CFD, which leads to errors in the angle-of-attack computation. We derive an expression for the error in the lift force from vortex considerations and show it to be a function of chord, the smearing length scale used in distributing the AL forces over the numerical domain and the number of grid cells per smearing length scale. Thereby demonstrating that the required number of grid cells-contrary to current belief-needs to grow faster than the inverse of the smearing length scale refinement to maintain the error level. We additionally show that the error can be large for the commonly used ratio of 2 grid cells per length scale, especially if the latter is relatively small with respect to the rotor radius. Ultimately, the recommendation is to always run with the largest smearing length scale possible for the specific application in conjunction with a smearing correction, as this minimizes the error in the blade forces whilst reducing the computational resources required.
Placing two counter-rotating rotors of a Vertical Axis Wind Turbine (VAWT) can lead to a significant power enhancement and a faster wake resorption. This global power output is directly related to the spacing between both rotors permitting a mutual confinement effect. In addition, the relative direction of angular velocity of both rotors can strongly impact the overall performances of the machine. A range of two-dimensional (2D) Unsteady Reynolds Averaged Navier-Stokes (URANS) simulations has been managed in order to study the aerodynamic interactions occurring in a pair of VAWT. By comparing with a single-rotor of VAWT, it has been shown than the global power enhancement of a double-rotor VAWT is linked with an extension of the lift production range in one of the two first quartiles of the upwind path. Moreover, the region of the extra power generation seems to be dependant on the relative rotational directions of counter-rotating rotors. In all cases, the extent of lift generation can be associated with a suppression of the cross-stream velocity induced by the confinement of the neighbouring turbine. This local flow perturbation, closed to the inner region, leads to an augmentation of the incidence experienced by the blades in the upwind path, increasing the global lift and torque recovered by the turbine.
Wind turbine leading edge erosion is a complex installation site-dependent process that spoils the aerodynamic performance of wind turbine rotors. This gradual damage process often starts with the formation of pits and gouges leading ultimately to skin delamination. This study demonstrates the application of open source parametric CAD functionalities for the generation of blade geometries with leading edge erosion damage consisting of pits and gouges. This capability is key to the development of high-fidelity computational aerodynamics frameworks for both advancing knowledge on eroded blade aerodynamics, and quantifying energy losses due to erosion. The considered test case is an offshore 5 MW turbine featuring leading edge pit and gouge damage in the outboard part of its blades. The power and loads of the nominal and damaged turbines are determined by means of a blade element momentum theory code using airfoil force data obtained with 3D Navier-Stokes computational fluid dynamics. An annual energy loss between about 1 and 2.5 percent of the nominal annual energy yield is encountered for the considered leading edge damages. The benefits of adaptive power control strategies for mitigating erosion-induced energy losses are also highlighted.
Reliable predictions of the aero-and hydrodynamic loads acting on floating offshore wind turbines are paramount for assessing fatigue life, designing load and power control systems, and ensuring the overall system stability at all operating conditions. However, significant uncertainty affecting both predictions still exists. This study presents a cross-comparative analysis of the predictions of the aerodynamic loads and power of floating wind turbine rotors using a validated frequency-domain Navier-Stokes Computational Fluid Dynamics solver, and a state-of-the-art Blade Element Momentum theory code. The considered test case is the National Renewable Energy Laboratory 5 MW turbine, assumed to be mounted on a semi-submersible platform. The rotor load and power response at different pitching regimes is assessed and compared using both the high-and low-fidelity methods. The overall qualitative agreement of the two prediction sets is found to be excellent in all cases. At a quantitative level, the high-and low-fidelity predictions of both the mean rotor thrust and the blade out-of-plane bending moments differ by about 1 percent, whereas those of the mean rotor power differ by about 6 percent. Part of these differences at high pitching amplitude appear to depend on differences in dynamic stall predictions of the approaches.
In aerodynamics, as in many engineering applications, a parametrised mathematical model is used for design and control. Often, such models are directly estimated from experimental data. However, in some cases, it is better to first identify a so-called nonparametric model, before moving to a parametric model. Especially when nonlinear effects are present, a lot of information can be gained from the nonparametric model and the resulting parametric model will be better. In this article, we estimate a nonparametric model of the lift force acting on a pitching wing, using experimental data. The experiments are done using the Active Aeroelastic Test Bench (AATB) setup, which is capable of imposing a wide variety of motions to a wing. The input is the angle of attack and the output is the lift force acting on the NACA 0018 wing. The model is estimated for two different types of input signal, swept sine and odd-random multisine signals. The experiments are done at two different pitch offset angles (5 and 20) with a pitch amplitude of 6, covering both the linear and nonlinear aerodynamic flow regime. In the case of odd-random multisines nonlinearity on the FRF is also estimated. We show that the level and characterisation of the nonlinearity in the output can be resolved through a nonparametric model, and that it serves as a necessary step in estimating parametric models.
The analysis of wind turbines relies on aero-hydro-servo-elastic simulation tools. OC3, 4, 5, 6 projects showed that much effort is required to obtain consistency in numerical models set up and the agreement in the simulation results. To mitigate the uncertainty in the model setup and to reduce the time spent on its verification, a robust verification procedure is necessary. The presented verification procedure provides a structured and efficient way of checking and comparing aeroelastic wind turbine models. In case a discrepancy between the two models or the model and documentation is found, a procedure for finding the source of this discrepancy is suggested. During several successful applications of the presented verification procedure, it proved to reduce the effort, the number of iteration loops and thus the consumed time that is required to achieve a verified model.