On the effect of nano-injectors on conduction in silicon p-i-n diodes

P–i–n diodes are widely used in power electronics [1-2], solar cells [3], light detection [4] and also light generation [5]. Contrary to the case of light detection or conversion, light generation is usually achieved by biasing the device in forward mode, in a condition of carrier injection. Depending on its level, the device can operate in regimes controlled by respectively generation/recombination current, diffusion current or the so called series resistance [6]. The injection level also controls the balance between the recombination mechanisms, and it is commonly controlled via the applied bias, which could be fixed by the specific application rather then being a free parameter. A possible approach to better control the injection level is to modify the features of the carrier injectors, for instance by thinning down the junction area [7] or reducing the injectors itself to a nanometer scale [8]. A practical way to realize nano-injectors is to embed the intrinsic region in oxide and create the connection between the intrinsic region and the two extension regions via antifuses, as realized in [9]. The size and properties of the antifuses can be controlled electrically, making it suitable to analyze the effects of progressive scaling of the dimensions of carrier injectors. In this work, we compare electrical behaviors of a standard p-i-n diode with antifuse p-i-n diodes programmed at different conditions. Electrical I-V measurements are performed at temperatures between -20 and 200 °C (I-V-T characteristics) in order to investigate the dominant mechanisms in the conduction

The Influence Of Water Velocity And Depth On Prey Detection And Capture By Juvenile Coho Salmon And Steelhead: Implications For Habitat Selection And Segregation

Thesis (Ph.D.) University of Alaska Fairbanks, 2005I studied the effects of water velocity and depth on drift-foraging by juvenile coho salmon and steelhead to assess how these influence their reported habitat segregation into pools and riffles, respectively. I used three-dimensional video analysis of stream-tank foraging experiments to test how velocity and depth influence prey capture probabilities, and the geometry and dynamics of prey detection and capture. I used the experimental results to develop net energy intake models to predict optimal foraging velocities for coho and steelhead. Prey capture probabilities for both coho and steelhead declined from $65% to 10% with an increase in velocity from 0.29 to 0.61 m · sec -1, with little difference between the species. Capture maneuver characteristics were similar for both species, including reduced prey detection distance and capture probabilities within the capture area, constant prey interception speed, and increasing return speed. I conclude that faster velocity reduces prey capture success by coho and steelhead, but that differences in capture abilities are not responsible for habitat segregation. Prey capture probabilities for both species were constant at ~40% at depths from 0.15 to 0.60 m, with little difference between the species. Capture maneuver characteristics were similar for both species, including increased prey detection distance and interception speed, and constant return speed. I predict that prey capture rate increases proportionally to water depth for coho and steelhead, but that differences in capture probabilities are not responsible for habitat segregation. I used the experimental results to develop net energy intake models that predicted optimum foraging velocities of 0.29 m · s-1 for coho and 0.30 m · s-1 steelhead. Modeled 10% and 25% increases in swimming costs for coho reduced optimum velocity by 0 and 0.01 m · s-1, respectively. These results, coupled with those from the depth experiments, suggest that habitat segregation may be due to factors other than short-term foraging considerations. I propose that these are largely selective mechanisms such as size-based habitat selection, differences in growth trajectories, or prey specialization. I do not discount the possibility that interactive mechanisms are also important, especially at periods of high fish density or limited prey availability

Fast three dimensional r-adaptive mesh redistribution

This paper describes a fast and reliable method for redistributing a computational mesh in three dimensions which can generate a complex three dimensional mesh without any problems due to mesh tangling. The method relies on a three dimensional implementation of the parabolic Monge–Ampère (PMA) technique, for finding an optimally transported mesh. The method for implementing PMA is described in detail and applied to both static and dynamic mesh redistribution problems, studying both the convergence and the computational cost of the algorithm. The algorithm is applied to a series of problems of increasing complexity. In particular very regular meshes are generated to resolve real meteorological features (derived from a weather forecasting model covering the UK area) in grids with over 2×107 degrees of freedom. The PMA method computes these grids in times commensurate with those required for operational weather forecasting

Methane emission from soil under long-term no-till cropping systems.

Methane (CH4) emission from agricultural soils increases dramatically as a result of deleterious effect of soil disturbance and nitrogen fertilization on methanotrophic organisms; however, few studies have attempted to evaluate the potential of long-term conservation management systems to mitigate CH4 emissions in tropical and subtropical soils. This study aimed to evaluate the long-term effect (>19 years) of no-till grass- and legume-based cropping systems on annual soil CH4 fluxes in a formerly degraded Acrisol in Southern Brazil. Air sampling was carried out using static chambers and CH4 analysis by gas chromatography. Analysis of historical data set of the experiment evidenced a remarkable effect of high C- and N-input cropping systems on the improvement of biological, chemical, and physical characteristics of this no-tilled soil. Soil CH4 fluxes, which represent a net balance between consumption () and production (+) of CH4 in soil, varied from 40 2 to +62 78 mg C m2 h1. Mean weighted contents of ammonium (NH4+–N) and dissolved organic carbon (DOC) in soil had a positive relationship with accumulated soil CH4 fluxes in the post-management period (r2 = 0.95, p = 0.05), suggesting an additive effect of these nutrients in suppressing CH4 oxidation and stimulating methanogenesis, respectively, in legumebased cropping systems with high biomass input. Annual CH4 fluxes ranged from 50 610 to +994 105 g C ha1, which were inversely related to annual biomass-C input (r2 = 0.99, p = 0.003), with the exception of the cropping system containing pigeon pea, a summer legume that had the highest biologically fixed N input (>300 kg ha1 yr1). Our results evidenced a small effect of conservation management systems on decreasing CH4 emissions from soil, despite their significant effect restoring soil quality. We hypothesized that soil CH4 uptake strength has been off-set by an injurious effect of biologically fixed N in legume-based cropping systems on soil methanotrophic microbiota, and by the methanogenesis increase as a result of the O2 depletion in niches of high biological activity in the surface layer of the no-tillage soil

Properties of potential eco-friendly gas replacements for particle detectors in high-energy physics

Gas detectors for elementary particles require F-based gases for optimal performance. Recent regulations demand the use of environmentally unfriendly F-based gases to be limited or banned. This work studies properties of potential eco-friendly gas replacements by computing the physical and chemical parameters relevant for use as detector media, and suggests candidates to be considered for experimental investigation

Properties of potential eco-friendly gas replacements for particle detectors in high-energy physics

Modern gas detectors for detection of particles require F-based gases for optimal performance. Recent regulations demand the use of environmentally unfriendly F-based gases to be limited or banned. This review studies properties of potential eco-friendly gas candidate replacements.Comment: 38 pages, 9 figures, 8 tables. To be submitted to Journal of Instrumentatio

Thermal performance of finned-tube thermoacoustic heat exchangers in oscillatory flow conditions

Heat exchangers play a key role in the overall performance of thermoacoustic devices. Due to the complex nature of oscillatory flows, the underlying mechanism of heat transfer in oscillatory flows is still not fully understood. This work investigates the effect of fin length and fin spacing on the thermal performance of finned-tube heat exchangers. The heat transfer rate between two finned-tube heat exchangers arranged side-by-side in an oscillatory flow was measured over a range of testing conditions. The results are presented in terms of heat transfer coefficient and heat transfer effectiveness. Comparisons are made between experimental results of this work and a number of models, such as, the Time-Average Steady-Flow Equivalent (TASFE) model, the Root Mean Square Reynolds Number (RMS-Re) model and the boundary layer conduction model, as well as several empirical correlations in literature. A new empirical correlation is proposed to be used for the prediction of thermal performance for finned-tube heat exchangers in oscillatory flows. The uncertainties associated with the measurement of heat flux are estimated

Candidate eco-friendly gas mixtures for MPGDs

Modern gas detectors for detection of particles require F-based gases for optimal performance.Recent regulations demand the use of environmentally unfriendly F-based gases t o be limited or banned. This review studies properties of potential eco-friendly gas candidate replacements