17,187 research outputs found

    Technique for producing bipolar and MOS field effect transistors on a single chip

    Get PDF
    Several cycles of photoetching, dopant deposition, and drive-in produce selectively-doped regions and semiconductor junctions within a single chip

    Urban and regional land use analysis: CARETS and census cities experiment package

    Get PDF
    The author has identified the following significant results. Temperatures in degrees Celsius were derived from PCM counts using the Pease's modified gray window technique. The Outcalt simulator was setup on the USGS computer. The input data to the model are basically meteorological and geographical in nature. The output data is presented in three matrices

    RHESSI and SOHO/CDS Observations of Explosive Chromospheric Evaporation

    Full text link
    Simultaneous observations of explosive chromospheric evaporation are presented using data from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Coronal Diagnostic Spectrometer (CDS) onboard SOHO. For the first time, co-spatial imaging and spectroscopy have been used to observe explosive evaporation within a hard X-ray emitting region. RHESSI X-ray images and spectra were used to determine the flux of non-thermal electrons accelerated during the impulsive phase of an M2.2 flare. Assuming a thick-target model, the injected electron spectrum was found to have a spectral index of ~7.3, a low energy cut-off of ~20 keV, and a resulting flux of >4x10^10 ergs cm^-2 s^-1. The dynamic response of the atmosphere was determined using CDS spectra, finding a mean upflow velocity of 230+/-38 km s^-1 in Fe XIX (592.23A), and associated downflows of 36+/-16 km s^-1 and 43+/-22 km s^-1 at chromospheric and transition region temperatures, respectively, relative to an averaged quiet-Sun spectra. The errors represent a 1 sigma dispersion. The properties of the accelerated electron spectrum and the corresponding evaporative velocities were found to be consistent with the predictions of theory.Comment: 5 pages, 4 figures, ApJL (In Press

    Cosmic Pathways for Compact Groups in the Milli-Millennium Simulation

    Full text link
    We detected 10 compact galaxy groups (CGs) at z=0z=0 in the semi-analytic galaxy catalog of Guo et al. (2011) for the milli-Millennium Cosmological Simulation (sCGs in mGuo2010a). We aimed to identify potential canonical pathways for compact group evolution and thus illuminate the history of observed nearby compact groups. By constructing merger trees for z=0z=0 sCG galaxies, we studied the cosmological evolution of key properties, and compared them with z=0z=0 Hickson CGs (HCGs). We found that, once sCG galaxies come within 1 (0.5) Mpc of their most massive galaxy, they remain within that distance until z=0z=0, suggesting sCG "birth redshifts". At z=0z=0 stellar masses of sCG most-massive galaxies are within 1010M/M101110^{10} \lesssim M_{\ast}/M_{\odot} \lesssim 10^{11}. In several cases, especially in the two 4- and 5-member systems, the amount of cold gas mass anti-correlates with stellar mass, which in turn correlates with hot gas mass. We define the angular difference between group members' 3D velocity vectors, Δθvel\Delta\theta_{\rm vel}, and note that many of the groups are long-lived because their small values of Δθvel\Delta\theta_{\rm vel} indicate a significant parallel component. For triplets in particular, Δθvel\Delta\theta_{\rm vel} values range between 2020^{\circ} and 4040^{\circ} so that galaxies are coming together along roughly parallel paths, and pairwise separations do not show large pronounced changes after close encounters. The best agreement between sCG and HCG physical properties is for MM_{\ast} galaxy values, but HCG values are higher overall, including for SFRs. Unlike HCGs, due to a tail at low SFR and MM_{\ast}, and a lack of M1011MM_{\ast}\gtrsim 10^{11}M_{\odot} galaxies, only a few sCG galaxies are on the star-forming main sequence.Comment: Style fixes to better match ApJ published version. Uses likeapj1.1 style files: 17 pages, 13 figures, 2 tables. LaTex style files available at https://github.com/qtast/likeapj/releases/lates

    Impingement of Water Droplets on NACA 65A004 Airfoil at 8 deg Angle of Attack

    Get PDF
    The trajectories of droplets in the air flowing past an NACA 65AO04 airfoil at an angle of attack of 8 deg were determined.. The amount of water in droplet form impinging on the airfoil, the area of droplet impingement, and the rate of droplet impingement per unit area on the airfoil surface were calculated from the trajectories and presented to cover a large range of flight and atmospheric conditions. These impingement characteristics are compared briefly with those previously reported for the same airfoil at an angle of attack of 4 deg

    Observation of blue-shifted ultralong-range Cs2_{2} Rydberg molecules

    Full text link
    We observe ultralong-range blue-shifted Cs2_{2} molecular states near ns1/2ns_{1/2} Rydberg states in an optical dipole trap, where 31n3431\leq n\leq34. The accidental near degeneracy of (n4)l(n-4)l and nsns Rydberg states for l>2l>2 in Cs, due to the small fractional nsns quantum defect, leads to non-adiabatic coupling among these states, producing potential wells above the nsns thresholds. Two important consequences of admixing high angular momentum states with nsns states are the formation of large permanent dipole moments, 15100\sim 15-100\,Debye, and accessibility of these states via two-photon association. The observed states are in excellent agreement with theory. Both projections of the total angular momentum on the internuclear axis are visible in the experiment

    Millimeter wave satellite concepts, volume 1

    Get PDF
    The identification of technologies necessary for development of millimeter spectrum communication satellites was examined from a system point of view. Development of methodology based on the technical requirements of potential services that might be assigned to millimeter wave bands for identifying the viable and appropriate technologies for future NASA millimeter research and development programs, and testing of this methodology with selected user applications and services were the goals of the program. The entire communications network, both ground and space subsystems was studied. Cost, weight, and performance models for the subsystems, conceptual design for point-to-point and broadcast communications satellites, and analytic relationships between subsystem parameters and an overall link performance are discussed along with baseline conceptual systems, sensitivity studies, model adjustment analyses, identification of critical technologies and their risks, and brief research and development program scenarios for the technologies judged to be moderate or extensive risks. Identification of technologies for millimeter satellite communication systems, and assessment of the relative risks of these technologies, was accomplished through subsystem modeling and link optimization for both point-to-point and broadcast applications

    A universal ionization threshold for strongly driven Rydberg states

    Full text link
    We observe a universal ionization threshold for microwave driven one-electron Rydberg states of H, Li, Na, and Rb, in an {\em ab initio} numerical treatment without adjustable parameters. This sheds new light on old experimental data, and widens the scene for Anderson localization in light matter interaction.Comment: 4 pages, 1 figur
    corecore