High-efficiency device research

Progress on research in high-efficiency silicon solar cells is presented. Topics addressed include: recombination measurement techniques, doped crystals, minority carrier transport, oxygen process in solar cells, solar cell models, loss mechanics in solar cells, high-efficiency metal insulators, dendritic web cells, and surface and bulk loss reduction by low-energy hydrogen doping

Vacuum lamination of photovoltaic modules

Vacuum lamination of terrestrial photovoltaic modules is a new high volume process requiring new equipment and newly develop materials. Equipment development, materials research, and some research in related fields and testing methods are discussed

The FOMC in 1976: progress against inflation

Federal Open Market Committee ; Inflation (Finance)

FEM investigation of leaky modes in hollow core photonic crystal fibers

Hollow-core holey fibers are promising candidates for low-loss guidance of light in various applications, e.g., for the use in laser guide star adaptive optics systems in optical astronomy. We present an accurate and fast method for the computation of light modes in arbitrarily shaped waveguides. Maxwell's equations are discretized using vectorial finite elements (FEM). We discuss how we utilize concepts like adaptive grid refinement, higher-order finite elements, and transparent boundary conditions for the computation of leaky modes in photonic crystal fibers. Further, we investigate the convergence behavior of our methods. We employ our FEM solver to design hollow-core photonic crystal fibers (HCPCF) whose cores are formed from 19 omitted cladding unit cells. We optimize the fiber geometry for minimal attenuation using multidimensional optimization taking into account radiation loss (leaky modes).Comment: 8 page

JCMmode: An Adaptive Finite Element Solver for the Computation of Leaky Modes

We present our simulation tool JCMmode for calculating propagating modes of an optical waveguide. As ansatz functions we use higher order, vectorial elements (Nedelec elements, edge elements). Further we construct transparent boundary conditions to deal with leaky modes even for problems with inhomogeneous exterior domains as for integrated hollow core Arrow waveguides. We have implemented an error estimator which steers the adaptive mesh refinement. This allows the precise computation of singularities near the metal's corner of a Plasmon-Polariton waveguide even for irregular shaped metal films on a standard personal computer.Comment: 11 page

Cooling Tower Considerations for Energy Optimizations

Energy conservation strategies and production economies involve more than examining the cooling tower fan consumption of horse power. Colder water provides vast potentials for savings. Ask yourself, "What is the dollar and energy utilization value if I can obtain 1°F colder water off my cooling tower than I am now getting?" Therefore, let us first examine the elements of the cooling tower to determine the areas of greatest potential improvement to generate that colder water. The air flow generated by the fan should first be looked at In both counterflow or crossflow towers to determine that maximum flow is available through pitching fans up to within the motor plate amperage limitations and fan stall point calculations. If applicable, new fiberglass state of the art fans can be installed and additional motor horse power added. However, the most dramatic improvement that can be obtained in producing colder water is to retrofit modern film fill to replace the old fashioned wood splash bar slats

Evolution of a coherent array of Bose-Einstein Condensates in a magnetic trap

We investigate the evolution process of the interference pattern for a coherent array of Bose-Einstein condensates in a magnetic trap after the optical lattices are switched off. It is shown that there is a decay and revival of the density oscillation for the condensates confined in the magnetic trap. We find that, due to the confinement of the magnetic trap, the interference effect is much stronger than that of the experiment induced by Pedri et al. (Phys. Rev. Lett, {\bf 87}, 220401), where the magnetic trap is switched off too. The interaction correction to the interference effect is also discussed for the density distribution of the central peak.Comment: RevTex, 17 pages,9 figures. E-mail: [email protected]