Definition study for photovoltaic residential prototype system

A site evaluation was performed to assess the relative merits of different regions of the country in terms of the suitability for experimental photovoltaic powered residences. Eight sites were selected based on evaluation criteria which included population, photovoltaic systems performance and the cost of electrical energy. A parametric sensitivity analysis was performed for four selected site locations. Analytical models were developed for four different power system implementation approaches. Using the model which represents a direct (or float) charge system implementation the performance sensitivity to the following parameter variations is reported: (1) solar roof slope angle; (2) ratio of the number of series cells in the solar array to the number of series cells in the lead-acid battery; and (3) battery size. For a Cleveland site location, a system with no on site energy storage and with a maximum power tracking inverter which feeds back excess power to the utility was shown to have 19 percent greater net system output than the second place system. The experiment test plan is described. The load control and data acquisition system and the data display panel for the residence are discussed

Multiple Charge State Beam Acceleration at Atlas

A test of the acceleration of multiple charge-state uranium beams was performed at the ATLAS accelerator. A 238U+26 beam was accelerated in the ATLAS PII linac to 286 MeV (~1.2 MeV/u) and stripped in a carbon foil located 0.5 m from the entrance of the ATLAS Booster section. A 58Ni9+ 'guide' beam from the tandem injector was used to tune the Booster for 238U+38. All charge states from the stripping were injected into the booster and accelerated. Up to 94% of the beam was accelerated through the Booster linac, with losses mostly in the lower charge states. The measured beam properties of each charge state and a comparison to numerical simulations are reported in this paper.Comment: LINAC2000, MOD0

Graphene field-effect transistors based on boron nitride gate dielectrics

Graphene field-effect transistors are fabricated utilizing single-crystal hexagonal boron nitride (h-BN), an insulating isomorph of graphene, as the gate dielectric. The devices exhibit mobility values exceeding 10,000 cm2/V-sec and current saturation down to 500 nm channel lengths with intrinsic transconductance values above 400 mS/mm. The work demonstrates the favorable properties of using h-BN as a gate dielectric for graphene FETs.Comment: 4 pages, 8 figure

Solitary Waves and Compactons in a class of Generalized Korteweg-DeVries Equations

We study the class of generalized Korteweg-DeVries equations derivable from the Lagrangian: L(l,p) = \int \left( \frac{1}{2} \vp_{x} \vp_{t} - { {(\vp_{x})^{l}} \over {l(l-1)}} + \alpha(\vp_{x})^{p} (\vp_{xx})^{2} \right) dx, where the usual fields $u(x,t)$ of the generalized KdV equation are defined by u(x,t) = \vp_{x}(x,t). This class contains compactons, which are solitary waves with compact support, and when $l=p+2$, these solutions have the feature that their width is independent of the amplitude. We consider the Hamiltonian structure and integrability properties of this class of KdV equations. We show that many of the properties of the solitary waves and compactons are easily obtained using a variational method based on the principle of least action. Using a class of trial variational functions of the form $u(x,t) = A(t) \exp \left[-\beta (t) \left|x-q(t) \right|^{2n} \right]$ we find soliton-like solutions for all $n$, moving with fixed shape and constant velocity, $c$. We show that the velocity, mass, and energy of the variational travelling wave solutions are related by $c = 2 r E M^{-1}$, where $r = (p+l+2)/(p+6-l)$, independent of $n$.\newline \newline PACS numbers: 03.40.Kf, 47.20.Ky, Nb, 52.35.SbComment: 16 pages. LaTeX. Figures available upon request (Postscript or hard copy

Heavy-Ion Beam Acceleration of Two-Charge States from an Ecr Ion Source

This paper describes a design for the front end of a superconducting (SC) ion linac which can accept and simultaneously accelerate two charge states of uranium from an ECR ion source. This mode of operation increases the beam current available for the heaviest ions by a factor of two. We discuss the 12 MeV/u prestripper section of the Rare Isotope Accelerator (RIA) driver linac including the LEBT, RFQ, MEBT and SC sections, with a total voltage of 112 MV. The LEBT consists of two bunchers and electrostatic quadrupoles. The fundamental frequency of both bunchers is half of the RFQ frequency. The first buncher is a multiharmonic buncher, designed to accept more than 80% of each charge state and to form bunches of extremely low longitudinal emittance (rms emittance is lower than 0.2 keV/u nsec) at the output of the RFQ. The second buncher is located directly in front of the RFQ and matches the velocity of each charge-state bunch to the design input velocity of the RFQ. We present full 3D simulations of a two-charge-state uranium beam including space charge forces in the LEBT and RFQ, realistic distributions of all electric and magnetic fields along the whole prestripper linac, and the effects of errors, evaluated for several design options for the prestripper linac. The results indicate that it is possible to accelerate two charge states while keeping emittance growth within tolerable limits.Comment: LINAC2000, MOD0

Space suit

A pressure suit for high altitude flights, particularly space missions is reported. The suit is designed for astronauts in the Apollo space program and may be worn both inside and outside a space vehicle, as well as on the lunar surface. It comprises an integrated assembly of inner comfort liner, intermediate pressure garment, and outer thermal protective garment with removable helmet, and gloves. The pressure garment comprises an inner convoluted sealing bladder and outer fabric restraint to which are attached a plurality of cable restraint assemblies. It provides versitility in combination with improved sealing and increased mobility for internal pressures suitable for life support in the near vacuum of outer space

Direct measurement of the transmission matrix of a mesoscopic conductor

We have developed an experimental approach which permits evaluation of the entire transmission matrix of a mesoscopic conductor. Results are presented from two new investigations enabled by this technique: (a) We study ballistic multiprobe conductors in the limit of weak probe coupling, and (b) we image modal features in the distribution function of electrons emerging from a quantum point contact