The NASA Lewis large wind turbine program

The program is directed toward development of the technology for safe, reliable, environmentally acceptable large wind turbines that have the potential to generate a significant amount of electricity at costs competitive with conventional electric generation systems. In addition, these large wind turbines must be fully compatible with electric utility operations and interface requirements. Advances are made by gaining a better understanding of the system design drivers, improvements in the analytical design tools, verification of design methods with operating field data, and the incorporation of new technology and innovative designs. An overview of the program activities is presented and includes results from the first and second generation field machines (Mod-OA, -1, and -2), the design phase of the third generation wind turbine (Mod-5) and the advanced technology projects. Also included is the status of the Department of Interior WTS-4 machine

Large wind turbines: A utility option for the generation of electricity

The wind resource is such that wind energy generation has the potential to save 6-7 quads of energy nationally. Thus, the Federal Government is sponsoring and encouraging the development of cost effective and reliable wind turbines. One element of the Federal Wind Energy Programs, Large Horizontal Axis Wind Turbine Development, is managed by the NASA Lewis Research Center for the Department of Energy. There are several ongoing wind system development projects oriented primarily toward utility application within this program element. In addition, a comprehensive technology program supporting the wind turbine development projects is being conducted. An overview is presented of the NASA activities with emphasis on application of large wind turbines for generation of electricity by utility systems

Large wind turbines: A utility option for the generation of electricity

The economic and technical potential of wind energy in the United States is discussed. Particular attention is given to the status of wind turbine operational experience as well as the environmental posture of the technology

Using stepped-care approaches within internet-based interventions for youth anxiety: Three case studies.

Background There are a lack of clear guidelines for the dissemination of Internet-based cognitive behaviour therapy (ICBT) for childhood and adolescent anxiety in routine care. While self-guided ICBT has greater reach than therapist-guided ICBT, it is plagued by problems of low program adherence and many young people are not successfully treated. It is important that we identify models of ICBT that are accessible, but provide the right support, at the right time to those who need it. Stepped-care models of ICBT offer one potential solution. Objective This case study examined the application of stepped-care within an ICBT intervention for childhood and adolescent anxiety, in which young people were stepped up from self-guided to therapist-guided ICBT. Methods Three case studies are presented and include young males (aged 11–12 years) who participated in BRAVE Stepped-Care, a new ICBT program incorporating two treatment steps: Step 1 – five sessions of self-guided ICBT and Step 2 – five sessions of therapist-guided ICBT. Participants completed diagnostic assessments at pre- and post-treatment, along with a battery of self-report questionnaires. Step-up requirements were determined at a mid-treatment assessment. Treatment response was determined by change on diagnostic severity and presence of diagnosis and changes in self-reported anxiety symptoms (through T-scores and Reliable Change Indices). Results In-depth examination of the three case studies showed that decisions to step-up from Step 1 to Step 2 were complex and required consideration of program engagement and adherence, as well as changes on self-reported anxiety, behavioural indicators of anxiety and parent perspectives. Results showed that non-responders at mid-treatment who were stepped-up to therapist-guided ICBT after Step 1 were able to increase engagement and response to treatment in Step 2, such that they were free of their primary anxiety diagnosis at post-treatment. Conclusions The findings highlight the importance of early assessment of engagement and non-response within self-guided ICBT programs for youth anxiety and the positive changes that can subsequently occur when therapist-guidance is introduced mid-treatment for non-responders. The efficacy of stepped-care ICBT models needs to be confirmed in larger randomised controlled trials

Probing the Melting of a Two-dimensional Quantum Wigner Crystal via its Screening Efficiency

One of the most fundamental and yet elusive collective phases of an interacting electron system is the quantum Wigner crystal (WC), an ordered array of electrons expected to form when the electrons' Coulomb repulsion energy eclipses their kinetic (Fermi) energy. In low-disorder, two-dimensional (2D) electron systems, the quantum WC is known to be favored at very low temperatures ($T$) and small Landau level filling factors ($\nu$), near the termination of the fractional quantum Hall states. This WC phase exhibits an insulating behavior, reflecting its pinning by the small but finite disorder potential. An experimental determination of a $T$ vs $\nu$ phase diagram for the melting of the WC, however, has proved to be challenging. Here we use capacitance measurements to probe the 2D WC through its effective screening as a function of $T$ and $\nu$. We find that, as expected, the screening efficiency of the pinned WC is very poor at very low $T$ and improves at higher $T$ once the WC melts. Surprisingly, however, rather than monotonically changing with increasing $T$, the screening efficiency shows a well-defined maximum at a $T$ which is close to the previously-reported melting temperature of the WC. Our experimental results suggest a new method to map out a $T$ vs $\nu$ phase diagram of the magnetic-field-induced WC precisely.Comment: The formal version is published on Phys. Rev. Lett. 122, 116601 (2019

Functional design for operational earth resources ground data processing

The author has identified the following significant results. Study emphasis was on developing a unified concept for the required ground system, capable of handling data from all viable acquisition platforms and sensor groupings envisaged as supporting operational earth survey programs. The platforms considered include both manned and unmanned spacecraft in near earth orbit, and continued use of low and high altitude aircraft. The sensor systems include both imaging and nonimaging devices, operated both passively and actively, from the ultraviolet to the microwave regions of the electromagnetic spectrum