Forecasting wind power production from a wind farm using the RAMS model

The importance of wind power forecast is commonly recognized because it represents a useful tool for grid integration and facilitates the energy trading. This work considers an example of power forecast for a wind farm in the Apennines in Central Italy. The orography around the site is complex and the horizontal resolution of the wind forecast has an important role. To explore this point we compared the performance of two 48 h wind power forecasts using the winds predicted by the Regional Atmospheric Modeling System (RAMS) for the year 2011. The two forecasts differ only for the horizontal resolution of the RAMS model, which is 3 km (R3) and 12 km (R12), respectively. Both forecasts use the 12 UTC analysis/forecast cycle issued by the European Centre for Medium range Weather Forecast (ECMWF) as initial and boundary conditions. As an additional comparison, the results of R3 and R12 are compared with those of the ECMWF Integrated Forecasting System (IFS), whose horizontal resolution over Central Italy is about 25 km at the time considered in this paper. Because wind observations were not available for the site, the power curve for the whole wind farm was derived from the ECMWF wind operational analyses available at 00:00, 06:00, 12:00 and 18:00 UTC for the years 2010 and 2011. Also, for R3 and R12, the RAMS model was used to refine the horizontal resolution of the ECMWF analyses by a two-years hindcast at 3 and 12 km horizontal resolution, respectively. The R3 reduces the RMSE of the predicted wind power of the whole 2011 by 5% compared to R12, showing an impact of the meteorological model horizontal resolution in forecasting the wind power for the specific site

Lessons from Two Years of Building Fusion Ignition Targets with the Precision Robotic Assembly Machine

The Precision Robotic Assembly Machine was developed to manufacture the small and intricate laser-driven fusion ignition targets that are being used in the world's largest and most energetic laser, the National Ignition Facility (NIF). The National Ignition Campaign (NIC) goal of using the NIF to produce a self-sustaining nuclear fusion burn with energy gain - for the first time ever in a laboratory setting - requires targets that are demanding in materials fabrication, machining, and assembly. We provide an overview of the design and function of the machine, with emphasis on the aspects that revolutionized how NIC targets are manufactured

Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

Inspection of the diamond-turned surfaces used for mounting an array of eight x-ray reflection gratings

This paper describes the use of a T-base diamond-turning machine as a measuring machine for inspecting the positional accuracy of the diamond-tuned surfaces of four attachment rails--parts that resemble precision step gauges. The attachment rails provide the precision mounting surfaces for a prototype array of eight X-ray reflection gratings for the European Space Agency`s (ESA) X-ray Multi-Mirror project (XMM). Each rail is 4.5 in. long with a cross-section of less than 0.1 in{sup 2}, and has eight protruding bosses spaced approximately 0.5 in. apart (Figure 1). A diamond-turned feature on each boss provides a mounting surface for one of the four corners of a grating. These surfaces are 0.018 in. high by 0.1 in. wide, and have a 12 in. cylindrical radius with an axis parallel to the boss protrusion (Figure 2). Together, the four rails provide eight sets of four coplanar points for mounting the gratings (Figure 3). Note that the gratings are not parallel to each other; they sweep through a 12 mrad angle from the first to eighth grating. To accommodate this fanned array, the normal directions (denoted by arrows in Figure 1) of the mounting surfaces on the bosses, at the rail centerline, also sweep through a 12 mrad angle from the first to eighth boss

A procedure for diamond turning KDP crystals

A procedure and the equipment necessary for single-point diamond flycutting (loosely referred to as diamond turning) potassium di-hydrogen phosphate (KDP) crystals are described. It is based on current KDP diamond turning activities at the Lawrence Livermore National Laboratory (LLNL), drawing upon knowledge from the Nova crystal finishing development during the 1980`s and incorporating refinements from our efforts during 1995. In addition to describing a step-by-step process for diamond turning KDP, specific discussions are included on the necessary diamond tool geometry and edge sharpness, cutting fluid, and crystal preparation, handling, cleaning, and inspection. The authors presuppose that the reader is already familiar with diamond turning practices

System Dynamics and Control System for a High Bandwidth Rotary Actuator and Fast Tool Servo

This paper explores some of the system dynamics and control issues for a short-stroke rotary actuator that we designed and tested for a new fast tool servo referred to as the 10 kHz rotary fast tool servo. The use of a fast tool servo (FTS) with a diamond turning machine for producing non-axisymmetric or textured surfaces on a workpiece is well known. In a previous paper [1] the authors provide details on the mechanical design and trade-off issues that were considered during the design phase for the fast tool servo. At the heart of that machine is the normal-stress variable reluctance rotary actuator described in more detail in this paper. In addition to producing the torque that is needed for the 10 kHz rotary fast tool servo, the actuator produces a force and is therefore referred to as a hybrid rotary/linear actuator. The actuator uses bias and steering magnetic fluxes for linearizing the torque versus current relationship. Certain types of electric engraving heads use an actuator similar in principle to our hybrid actuator. In the case of the engraving heads, the actuator is used to produce and sustain a resonating mechanical oscillator. This is in sharp contrast to the arbitrary trajectory point-to-point closed-loop control of the tool tip that we demonstrate with our actuator and the 10 kHz FTS. Furthermore, we demonstrate closed-loop control of both the rotary and linear degrees of freedom for our actuator. We provide a brief summary of the demonstrated performance of the 10 kHz rotary fast tool servo, and discuss the magnetic circuit for the actuator and some of the related control issues. Montesanti [2] provides a more detailed and thorough discussion on the 10 kHz rotary fast tool servo, the hybrid actuator, and the pertinent prior art