Electromagnetic energy transfer and switching in nanoparticle chain arrays below the diffraction limit

Electromagnetic energy transfer in plasmon wires consisting of chains of closely spaced metal nanoparticles can occur below the diffraction limit by means of coupled plasmon modes. Coherent propagation with group velocities that exceed 0.1 c is possible in straight wires and around sharp corners (bending radius much less than wavelength of visible light). Energy transmission through chain networks is possible at high efficiencies and is a strong function of the frequency and polarization direction of the plasmon mode. Although these structures exhibit transmission losses due to heating of about 3 dB/500 nm, they have optical functionality that cannot be obtained in other ways at a length scale ≪1 μm

Infrared testing of electronic components Final report, 5 Apr. 1965 - 5 Jun. 1966

Infrared radiation nondestructive test technique for electrical/electronic equipmen

Development of a Portfolio Management Approach with Case Study of the NASA Airspace Systems Program

A portfolio management approach was developed for the National Aeronautics and Space Administration s (NASA s) Airspace Systems Program (ASP). The purpose was to help inform ASP leadership regarding future investment decisions related to its existing portfolio of advanced technology concepts and capabilities (C/Cs) currently under development and to potentially identify new opportunities. The portfolio management approach is general in form and is extensible to other advanced technology development programs. It focuses on individual C/Cs and consists of three parts: 1) concept of operations (con-ops) development, 2) safety impact assessment, and 3) benefit-cost-risk (B-C-R) assessment. The first two parts are recommendations to ASP leaders and will be discussed only briefly, while the B-C-R part relates to the development of an assessment capability and will be discussed in greater detail. The B-C-R assessment capability enables estimation of the relative value of each C/C as compared with all other C/Cs in the ASP portfolio. Value is expressed in terms of a composite weighted utility function (WUF) rating, based on estimated benefits, costs, and risks. Benefit utility is estimated relative to achieving key NAS performance objectives, which are outlined in the ASP Strategic Plan.1 Risk utility focuses on C/C development and implementation risk, while cost utility focuses on the development and implementation portions of overall C/C life-cycle costs. Initial composite ratings of the ASP C/Cs were successfully generated; however, the limited availability of B-C-R information, which is used as inputs to the WUF model, reduced the meaningfulness of these initial investment ratings. Development of this approach, however, defined specific information-generation requirements for ASP C/C developers that will increase the meaningfulness of future B-C-R ratings

Educational Policy and Training Implications of Social Science Research: Lessons from an Inner City Elementary School

Participant observation research in an elementary school from 1989 to 1992 reinforces our understanding that often inner city children find a conflict between the behaviors and values that help them survive on the street and those that are expected in the middle-class educational system in which they are engaged on a day-to-day basis. While expecting middle-class responses, however, many teachers used archaic teaching strategies that have been abandoned in our best suburban schools. The research also makes clear the need for teachers to have high expectations for children while employing teaching methodologies that focus on individual students and their strengths and weaknesses. Policy recommendations are outlined that could alter the success of inner city education, if employed judiciously

Conceptual mechanization studies for a horizon definition spacecraft attitude control subsystem, phase A, part II, 10 October 1966 - 29 May 1967

Attitude control subsystem for spin stabilized spacecraft for mapping earths infrared horizon radiance profiles in 15 micron carbon dioxide absorption ban

It’s All About to Change: Implications of Reforming Grading & Assessment within a Public School District

Calls to reform grading systems and other assessment practices have been growing for several decades. There is consensus among many educators that grading and assessment practices that have been traditionally accepted as good practice are at best ineffective and at worst have a negative impact on raising achievement. Consequently, there is no single solution or methodology for grading that has emerged as the best practice. A variety of contemporary grading approaches have gained widespread popularity in recent years, typically being referred to as standards-based grading, standards-referenced grading, proficiency-based grading, or competency-based learning. A challenge, however, is that different school districts define these terms differently and models vary widely in their implementation. Although there is no single grading model that is the panacea for all of the ills of past practices, the researchers identified the common ground about what an effective system for grading and assessment should include. Even though further study is needed, the resounding evidence indicates that contemporary grading practices such as standards-based grading are a preferred model if the goal of grading is to accurately communicate student learning and achievement

Simulations of snow distribution and hydrology in a mountain basin

We applied a version of the Regional Hydro‐Ecologic Simulation System (RHESSys) that implements snow redistribution, elevation partitioning, and wind‐driven sublimation to Loch Vale Watershed (LVWS), an alpine‐subalpine Rocky Mountain catchment where snow accumulation and ablation dominate the hydrologic cycle. We compared simulated discharge to measured discharge and the simulated snow distribution to photogrammetrically rectified aerial (remotely sensed) images. Snow redistribution was governed by a topographic similarity index. We subdivided each hillslope into elevation bands that had homogeneous climate extrapolated from observed climate. We created a distributed wind speed field that was used in conjunction with daily measured wind speeds to estimate sublimation. Modeling snow redistribution was critical to estimating the timing and magnitude of discharge. Incorporating elevation partitioning improved estimated timing of discharge but did not improve patterns of snow cover since wind was the dominant controller of areal snow patterns. Simulating wind‐driven sublimation was necessary to predict moisture losses

Chandra and RXTE studies of the X-ray/gamma-ray millisecond pulsar PSR J0218+4232

We report on high-resolution spatial and timing observations of the millisecond pulsar PSR J0218+4232 performed with the Chandra X-ray Observatory (CXO) and the Rossi X-ray Timing Explorer (RXTE). With these observations we were able to study a) the possible spatial extent at X-ray energies of the DC source coincident with PSR J0218+4232 in detail (CXO), b) the relative phasing between the X-ray, radio and gamma-ray profiles (CXO and RXTE) and c) the spectral properties at energies beyond 10 keV (RXTE). We found no indications for extended emission at X-ray energies down to ~ 1 arcsec scales and confirmed the presence of a point-like DC-component. The 2 non-thermal pulses in the X-ray profile are found to be aligned with 2 of the 3 pulses visible at radio-frequencies and more importantly with the two gamma-ray pulses seen in the EGRET 100-1000 MeV pulse profile. The latter reduces now the random occurrence probability for the detected gamma-ray signal to ~ 1.E-6, which corresponds to a 4.9 sigma detection significance.Comment: 8 pages,7 figures, accepted for publication in Adv Sp Res: Proceedings of the 34th COSPAR Scientific Assembly held in Housto

Frequency Domain Reflectometry NDE for Aging Cables in Nuclear Power Plants

Degradation of the cable jacket, electrical insulation, and other cable components of installed cables within nuclear power plants (NPPs) is known to occur as a function of age, temperature, radiation, and other environmental factors. System tests verify cable function under normal loads; however, demonstration of some cable’s ability to perform under exceptional loads associated with design-basis events is essential to assuring plant integrity. The cable’s ability to perform safely over the initial 40-year planned and licensed life has generally been demonstrated and there have been very few age-related cable failures.With greater than 1000 km of power, control, instrumentation, and other cables typically found in an NPP, replacing all the cables would be a severe cost burden. Justification for life extension to 60 and 80 years requires a cable aging management program to justify cable performance under normal operation as well as accident conditions. A variety of tests are available to assess various aspects of electrical and mechanical cable performance, but none of these tests are suitable for all cable configurations nor does any single test confirm all features of interest. One particularly powerful test that is beginning to be used more and more by utilities is frequency domain reflectometry (FDR). FDR is a nondestructive electrical inspection technique used to detect and localize faults in power and communication system conductors along the length of a cable from a single connection point. For the measurement, two conductors in the cable system are treated as a transmission line, which propagates a low-voltage swept-frequency waveform to interrogate the cable length. Note that because the applied signal is low-voltage (\u3c5 volts), the test is completely nondestructive and poses no special safety concerns to operators. An inverse Fourier transform is used to convert the resulting frequency-domain data into a time-domain format, which can determine the physical location of signal reflections if the signal propagation velocity is known. FDR detects discontinuities in the electrical impedance that arise due to cable splices or similar changes along the path of the conductor pair. In addition, FDR has the potential to provide sensitivity to insulation degradation by detecting small changes in capacitance between the cable conductors being examined. Example changes that impact the insulation capacitance include exposure to heat, radiation, water damage, corrosion, or mechanical fatigue. The technique is also sensitive to cable bends, the particular lay of the cable in tray, proximity to other cable, and other factors that bear consideration when interpreting these tests. This paper examines various influences on the FDR approach and compares results of three different instruments capable of producing the FDR to assess accelerated aging cable damage among several NPP representative cables

Experimental and theoretical lifetimes and transition probabilities in Sb I

We present experimental atomic lifetimes for 12 levels in Sb I, out of which seven are reported for the first time. The levels belong to the 5p$^2$($^3$P)6s $^{2}$P, $^{4}$P and 5p$^2$($^3$P)5d $^{4}$P, $^{4}$F and $^{2}$F terms. The lifetimes were measured using time-resolved laser-induced fluorescence. In addition, we report new calculations of transition probabilities in Sb I using a Multiconfigurational Dirac-Hartree-Fock method. The physical model being tested through comparisons between theoretical and experimental lifetimes for 5d and 6s levels. The lifetimes of the 5d $^4$F$_{3/2, 5/2, 7/2}$ levels (19.5, 7.8 and 54 ns, respectively) depend strongly on the $J$-value. This is explained by different degrees of level mixing for the different levels in the $^4$F term.Comment: 10 page