Grid Width Research Articles

Analysis of series resistance of crystalline silicon solar cell with two-layer front metallization based on light-induced plating

Improving the front metallization quality of silicon solar cells should be a key to enhance cell performance. In this work, we investigated a two-layer metallization scheme involving light-induced plating (LIP) and tried to quantify its impact on the series resistance of the front grid metals and FFs on finished cells. To estimate the effect of LIP processing on a printed and fired seed layer, individual components of series resistance were measured before and after LIP processing. Among them, grid resistance and contact resistance were closely observed because of their large contribution to series resistance. To optimize the plating on the seed metal grid, the grid resistance of the two-layer metal grid structure was calculated as a function of cross section area of the plated layer. Contact resistivity of the grid before and after LIP processing was analyzed to understand the contact resistance reduction, as well. As a result, the efficiency of solar cells with 80 μm seed metal grid width increased by 0.3% absolute compared with conventional solar cells of 120 μm metal grid width. The total area of electrodes in conventional cells was 1800 mm 2 and electrodes area of LIP processed solar cells was 1400 mm 2. The efficiency gain was due to reduction of shadowing loss from 7.7% to 6.0% without the increase of resistance due to two-layer front metallization.

Effects of the geometrical configuration of a ventilation system on leaking hydrogen dispersion and accumulation

Hydrogen dispersion and accumulation in a partially open space with natural and forced ventilation are computationally investigated in this paper. After validating the present numerical method and assessing grid width against experimental data of a hallway, the present method is applied to a garage with dimensions of 2.6 m × 2.6 m × 2.6 m and leak flow rates of 0.5–4 standard cubic feet per minute (SCFM). In the simulations, different combinations of roof vents and door vents are considered by changing their sizes and positions. Based on the results, differences in concentration increase, the processes of hydrogen dispersion and accumulation, unsteadiness and vortical structures accompanying ventilation, are shown for natural and forced ventilation.

A filtered flame approach for simulation of unsteady laminar premixed flames

The simulation of laminar flames consists of capturing the evolution of a very large number of species that may react within a broad range of time scales. It results in a highly non-linear stiff numerical problem that requires large computational resources. In the present paper, an alternative approach for the simulation of unsteady premixed flames is proposed. The approach focuses on describing the flame using a single scalar only (so-called progress variable) on relatively coarse grids. The unresolved details of the flame structure are analysed and described in term of spatial filtering. A model originally developed for large eddy simulation is discussed in the framework of unsteady laminar flames. The ability of the present approach to represent the filtered flame structure is validated against detailed numerical simulations of freely propagating laminar flames. Further, simulations of steady and unsteady laminar Bunsen flames are presented with a focus on the influence of the numerical grid and filter width upon the flame dynamics.

초소형 자유전자 레이저 모듈에 대한 특성 연구

마이크로 칼럼 기술을 응용한 초소형 자유전자 레이저 모듈의 특성을 연구하였다. 초소형 자유전자 레이저는 전자 방출원과 방사광 발생 장치로 나뉜다. 방사광 발생 장치는 위글러(wiggler)라 불리는데 그리드(grid) 판으로 구성되어 있다. 전자가 위글러를 지나갈 때 규칙적으로 배열된 그리드에 인가된 전압에 의하여 전자의 궤적이 사인(sinusoidal) 함수 모양으로 주기적으로 변하여 방사광을 발생시킨다. 본 연구에서는 초소형 자유전자 레이저 위글러의 매개 변수에 따른 전자빔 궤적을 전산모사를 이용하여 분석하였다. 쌍을 이루는 위글러 간격, 그리드의 폭, 깊이, 주기, 그리고 그리드에 인가된 전압이 전자빔에 미치는 효과를 조사하였다. We investigated the miniaturized free electron laser(FEL) module based on microcolumn. The miniaturized FEL is composed of two parts: electron generation part and radiation emission part. The radiation emission part, called wiggler, consists of a grid plate. While the electrons are passing through the wiggler, electron trajectory shows sinusoidal curve caused by the periodically applied voltage on the grid, and then it give rise to radiation emission. We analyzed the wiggler parameters, grid width, depth, period, applied voltage and the pair wiggler space using 2-D simulation tool.

Inertial consistent subgrid model for large-eddy simulation based on the lattice Boltzmann method

The recently introduced inertial-range (IR) consistent Smagorinsky model and the classical Smagorinsky model are applied to the large-eddy simulation (LES) of decaying homogeneous isotropic turbulence based on the lattice Boltzmann method (LBM), which is implemented using the 19-velocity D3Q19 lattice model. The objectives of this study are to examine the effectiveness of the LES-LBM technique for study of turbulence and to extend and validate the efficiency of the inertial-range consistent Smagorinsky model for lattice Boltzmann fluid dynamics. The LES-LBM results are compared with the direct numerical simulation data as well as experimental data. The time evolution of the kinetic energy and the decay exponents of the dissipation rate, the velocity derivative skewness, and instantaneous energy spectra are analyzed. The dependency of behavior of the model coefficients on the ratio of grid width Δ and the Kolmogorov scale η is examined numerically. The results demonstrate that the LES-LBM in conjunction with the IR consistent Smagorinsky model can be used to simulate turbulence more satisfactorily than the standard Smagorinsky model.

The D-Diastereomer of ShK Toxin Selectively Blocks Voltage-gated K+ Channels and Inhibits T Lymphocyte Proliferation

The polypeptide toxin ShK is a potent blocker of Kv1.3 potassium channels, which are crucial in the activation of human effector memory T cells (T(EM)); selective blockers constitute valuable therapeutic leads for the treatment of autoimmune diseases mediated by T(EM) cells, such as multiple sclerosis, rheumatoid arthritis, and type-1 diabetes. The critical motif on the toxin for potassium channel blockade consists of neighboring lysine and tyrosine residues. Because this motif is sufficient for activity, an ShK analogue was designed based on D-amino acids. D-allo-ShK has a structure essentially identical with that of ShK and is resistant to proteolysis. It blocked Kv1.3 with K(d) 36 nm (2,800-fold lower affinity than ShK), was 2-fold selective for Kv1.3 over Kv1.1, and was inactive against other K(+) channels tested. D-allo-ShK inhibited human T(EM) cell proliferation at 100-fold higher concentration than ShK. Its circulating half-life was only slightly longer than that of ShK, implying that renal clearance is the major determinant of its plasma levels. D-allo-ShK did not bind to the closed state of the channel, unlike ShK. Models of D-allo-ShK bound to Kv1.3 show that it can block the pore as effectively as ShK but makes different interactions with the vestibule, some of which are less favorable than for native ShK. The finding that an all-D analogue of a polypeptide toxin retains biological activity and selectivity is highly unusual. Being resistant to proteolysis and nonantigenic, this analogue should be useful in K(+) channel studies; all-d analogues with improved Kv1.3 potency and specificity may have therapeutic advantages.

OS5-3-5 Micro-Crack Length Measurement Method in Ceramics by Using Grid Pattern Metal Film

In this study, the new and simple crack length measurement method by using grid pattern of Au film was suggested. Au film coated on the surface of a specimen by the ion sputtering method was cut like a comb by scanning laser beam condensed as a line, and the fine grid pattern film with the grid width, 10μm, and space width, 7μm, was made. Further, to confirm the validity of the method the crack growth test was carried out with four-point bending using soda-lime glass specimens. As a result, it was confirmed that the crack length measurement using the fine grid pattern film could express the relationship between the crack growth rate and stress intensity factor of the material in detail, and the possibility of the application to the other ceramic materials was also showed.

The position of impact of a ball striking a cricket bat: assisting coaches with performance analysis of cricket technique and skill levels.

The purpose of this study was to use the data collected in three previous studies (Stretch et al 1998/99, Stretch et al 2000 and Stretch et al 2002) to determine variations, if any, between the position of impact on the cricket bat for cricketers of different batting skill levels, as well as for various strokes played off the front foot. The cricket bat was divided into a Cartesian grid (width - 0 to 110 mm; height - 0 to 555mm) and instrumented to identify the ball impact point, while the software stored biographical and stroke data (McKellar et al. 1998). All three studies used a similar data collection method with a bowling machine project the ball at a velocity of 100 to 105 km h-1 on a line about 0.1 m outside the batsman’s off stump and on a length that enabled the batsman to play all the strokes off the front foot. Typically each player took part in three testing sessions of 60 deliveries (10 overs), with their normal training programmes supplemented with some additional form of intervention. Players were divided into two groups (Batsmen and Bowlers), as well as classified at the highest level at which they had played at the time of data collection (Provincial and Club). The results of the 60 cricketers and 9052 recorded impacts showed non-significant variations in the impact location for the Provincial and Club cricketers. Significant differences (p < 0.05) occurred between the impact points for the batsmen and bowlers, as well as between all the strokes with the exception of the off-drive. As the strokes were played wider of the pitch, the off- and cover drives on the off-side and the on-drive and leg glance on the on-side, the impact point was further from the midline of the bat thus increasing the risk of being dismissed. The instrumented bat was devised to assess the accuracy and consistency of stroke reproduction and the effects of various intervention modalities. It has shown that it has implications for performance analysis of cricket technique and skill levels.

A subgridding technique for the complex nonstandard FDTD method

AbstractIn this paper, a subgridding method is proposed for the two‐dimensional Complex Nonstandard FDTD (CNS‐FDTD) method. Taking into account the characteristics of the CNS‐FDTD method, new spatial interpolation, difference operator interpolation, and time interpolation are introduced. In order to demonstrate the usefulness of the proposed subgridding method, it is compared with the cases in which linear interpolation and quadratic interpolation of the conventional method are used for the main grids and local grids. It is found that the present subgridding method is superior to the conventional method in terms of stability and accuracy. Further, in the scattering analysis of a large rectangular cavity loaded with a lossy medium, the present subgridding method demonstrated substantial improvement in computation time and number of grids over CNS‐FDTD calculations with the local grid width over the entire space. As a subgridding method, a connection method is explained in a general case where the spatial division ratio of the main grids and local grids is 1:3. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(8): 1–9, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20078

Multigrid methods with web-splines

We describe and analyze a multigrid algorithm for finite element approximations of second order elliptic boundary value problems with weightedextended b-splines (web-splines). This new technique provides high accuracy with relatively low-dimensional subspaces, does not require any grid generation, and is ideally suited for hierarchical solution techniques. In particular, we show that the standard W-cycle yields uniform convergence, i.e., the required number of iterations is bounded independent of the grid width.

Local Texture and Magnetic Levitation Force of YBaCuO Cylinders

YBaCuO cylinders are needed for the construction of magnetic bearings. In these YBaCuO cylinders superconducting currents are induced by approaching a permanent magnet. To obtain a high induced current in concentric circles around the cylinder axis of the YBaCuO cylinder, the c-axes of the crystalline domains have to be aligned as well as possible in normal direction to the induced superconducting currents. This condition is fulfilled, if the c-axes of the domains are in parallel to the cylinder axis of the YBaCuO cylinder. But it allows the c-axes to be tilted each in a same plane with the cylinder axis. Global texture cannot distinguish between different tilting directions of the c-axes of individual parts of the specimen. Therefore, the cylindrical specimen has been cut into 9 pieces, one central piece and 8 boundary pieces. An equal area texture measurement by neutron diffraction has been performed at the Geesthacht reactor with a grid width of 1.5° in the central region of the pole sphere up to Δ X = 19.5° from the cylinder axis of the YBaCuO cylinder. For each of the 9 parts of the specimen this neutron texture measurement has been performed. The best suited distribution of the c-axes has been determined in the central piece. The orientation distribution of the c-axes has been found to be broadened at the boundary pieces, especially in diagonal direction of the rectangular seed crystal which was implanted in the molten state into the center of the recrystallized specimen.

The problem of scaling in grid-related hydrological process modelling

This article shows some important scaling aspects that exist in hydrological process grid modelling with GIS, with respect to selecting the optimal grid width. Hydrologically relevant space parameter fields should often be regarded as self-similar fractals for which certain invariance characteristics are applied. These characteristics are especially important if there is an extensive change in the model grid width. The self-similarity generates simple scaling laws, which can be used for rescaling procedures. © 1997 John Wiley & Sons, Ltd.

Plasma cathode preionized atmospheric pressure HF chemical laser

The performance of an electric discharge, plasma-cathode-preionized, atmospheric-pressure HF chemical laser was investigated and the laser was geometrically optimized. The preionization electron density was measured at atmospheric pressure in helium and in a mixture of SF 6 + H 2 diluted by helium. The measured preionization density is n e ≈ 6.7 × 10 9−2 × 10 10cm −3, which is higher than the minimum critical density required for a self-sustained, homogeneous discharge of atmospheric-pressure electronegative gases. We have found improvement in laser specific energy for a diluted gas mixture of SF 6 + H 2 due to reduction in SF 6 concentration. The effects of inter-electrode gap height and plasma cathode grid width on laser performance were also investigated and are reported.

Application of a Junction Field Effect Transistor Structure to a Low Loss Diode

A novel low loss diode with junction grids has been proposed. Numerical simulations reveal that, for this diode, designing a submicron grid width improves the tradeoff characteristics between the forward voltage drop and the leakage current, leading to characteristics superior to those of the Schottky barrier diode. The introduction of a lateral silicon-on-insulator (SOI) structure into the proposed diode is attractive for achieving such a small grid width. The simulation also demonstrates design methods for channel doping and thickness of the buried oxide layer in the SOI diode.

Identification and observation of desertification processes with the aid of measurements from space: Results from the European Field Experiment in Desertification-threatened Areas (EFEDA)

The ECHIVAL Field Experiment in Desertification-threatened Areas (EFEDA) addresses the question of desertification from the viewpoint of changing interactions between the land surface and the atmosphere under varying climatic conditions. The basic tool to improve our understandin of these processes are Soil-Vegetation-Atmosphere-Transfer (SVAT) and climate models. In testing techniques for deriving the needed input data from observations from space, EFEDA requires high-precision data sets that can be used to aggregate desertification-related land-surface characteristics into the scale up to the grid width of global climate models (10(4)-10(5) km(2)). In this context schemes have been developed to infer from satellite measurements fluxes at the surface. To validate the information inferred from observations in space, ground measurements have been performed on 2500 km(2) of Castilla-La Mancha, Spain, during the drying periods of the summers of 1991 and 1994. Ultimately EFEDA aims to determine cumulative fluxes over longer periods to allow discrimination between natural variability and trends over large areas, such as the land around the Mediterranean. To recalibrate and adjust the algorithms used to infer information about the land surfaces from satellite measurements, "anchor stations" are proposed for critical areas to provide collateral information and continuous quality control of inferred information.

Habitat and spatial requirements of the eastern barred bandicoot (Perameles gunnii) at Hamilton, Victoria

Perameles gunnii was greatly affected by the introduction of European agriculture to the volcanic plains in Victoria. At Hamilton, agricultural areas possessed little structural complexity and supported a fairly homogeneous composition of pasture species that were generally shorter than 100 mm because of heavy stock grazing. No P. gurznii were caught in agricultural areas at Hamilton. At the Hamilton Municipal Tip, most captures and nest sites occurred where food resources and structural complexity were greatest. Descriptions of 16 diurnal nest sites indicated that a range of natural and artificial materials was used for shelter, including fallen branches, sawn timber, cement culverts, galvanised iron, and scrap metal. Earthworms were most frequently observed in faecal and stomach material, while beetles and crickets were also common. Optimal habitat for P. gunnii was defined by high structural complexity and habitat heterogeneity. Older P. gunnii may usurp optimal habitat and force subordinate adult females into sub-optimal habitat. Associated with their occupation of optimal habitat, older P. gunnii may utilise smaller nocturnal foraging areas. Analysis of the movement of P. gunnii within the Hamilton Municipal Tip indicated that males occupied significantly larger nocturnal foraging areas than females. Mean female and male home ranges (defined by Minimum Convex Polygon analysis) were 1.6 ha (n = 13, range 0.02-5.9 ha) and 4 ha (n = 18, range 0.8-9.0 ha), respectively. Also, nocturnal foraging areas were analysed on the basis of pattern of use of an area, and these were referred to as utilisation distributions. The mean utilisation distributions (defined by Minimum Area v. Probability [0.95] analysis) for females and males were 0.64 ha (n = 13, range 0.01-4.7 ha) and 4.0 ha (n = 18, range 0.01-19.6 ha), respectively. Mean female and male observed range lengths were 173 m (tz = 26, range 0-364 m) and 249 m (n = 34, range 50430 m), respectively. Mean ( +/-s.e ) observed range length (214+/-20, n = 60, range 50-430 m) was less than half the grid width (500 m), which suggests that grid size did not negatively bias the calculated home-range sizes.

Quantum lithography

The edge definition and the interior filling of pattern features are commonly performed using the same exposing beam regardless of the feature size. Separating the two processes, as first proposed by Fulton et al. [Appl. Phys. Lett. 42, 752 (1983)], improves the efficiency of the mask making process and adds ‘‘smartness’’ to the substrate, i.e., the pattern generating tool need only provide the minimum information; the substrate and process are configured to convert the minimum information into the necessary pattern. We describe an improved level of smartness on substrates: we view the mask as a bitmapped lattice of independent pixel elements (pels), each having a given shape and carrying the relevant edge information; the desired pattern would be generated by selectively addressing a subset of the lattice and modifying the optical properties of its pels. The feature edges are effectively ‘‘quantized’’ in the sense that they can exist only in some specific places. In the edge definition step, a very fine grid whose edges are within the specifications on edge positional accuracy and precision, is inscribed on the mask blank by its manufacturer using a high resolution and high precision lithographic technique. The pitch is such that the size of the resulting tiles equals the minimum feature size of the pattern to be delineated. The limitation on the grid width is that it is not imaged by the optics upon the exposure of the mask. Once the grid is defined, the pattern can be customized by the user simply by tagging those tiles that constitute the pattern. We describe here the general principles, advantages, fabrication, and exposure of ‘‘quantum lithography’’ masks.

A Statistically-Derived Subgrid-Scale Kinetic Energy Model for the Large-Eddy Simulation of Turbulent Flows

A subgrid-scale (SGS) kinetic energy model for the large-eddy simulation (LES) of turbulent flows is constructed with the aid of the statistical results obtained from the two-scale direct-interaction approximation. In this model, the SGS Reynolds stress is written in terms of a generalized SGS eddy-viscosity representation which is expressed by using the SGS kinetic energy and the characteristic grid width. A model equation for the SGS kinetic energy is combined with the grid-scale Navier-Stokes and continuity equations to lead to an LES model of one-equation type. The usual Smagorinsky model is derived as its special case, and critical comparison is made between them.

A high short-circuit current inversion layer poly-Si solar cell

An IL/MIS poly-Si solar cell is fabricated. Its short-circuit current reveals a very high value of 32.8 mA/cm2. During fabrication, the front side of poly-Si wafer has to be polished for 2 min to obtain a mirror-like surface. The thin oxide was grown at 400°C in N 2 /O 2 ambient, and SiO film was evaporated at a rate of 5 A/s which produces the highest V OC and I SC . The grid width and grid spacing has been optimized experimentally to be 7 and 100 µm, respectively. Under AM1 light intensity, the best cell shows a conversion efficiency of 10.41 percent (total area), short-circuit current density of 32.8 mA/cm2, and open-circuit voltage of 0.544 V.

The Grid Method in Estimating the Path Length of a Moving Animal

SUMMARY (1) The length of a path covered by a moving animal may be estimated by counting the number of times the animal crosses any line of a grid and applying a conversion factor. (2) Some factors are based on the expected distance through a randomly crossed square; another on the expected crossings of a randomly superimposed grid. (3) Paths of walking blowflies were drawn and their lengths measured. (4) They were also estimated by means of five different conversion factors. (5) The factor 47r times grid width based on the expected numbers of crossings of a grid superimposed at random over the curve gave the best results. (6) Variability depends on the twistiness of the curve, the width of the grid, and the length of the curve. (7) No formula for the standard error of the estimated curve length is available.