Predicting Spatial Distributions of Demersal Fishes off Central California

Seafloor maps are often used in species distribution modeling (SDM), where maps are paired with fish observations to create models predicting habitat suitability, species density, or species biomass. Problems with the current use of SDM include limited understanding of species relationships with benthic morphology, lack of practical model testing, and deficiency of information on the effects of map resolution on population estimates. A drop camera was used to gather observations of fishes along Central California and paired with remotely sensed bathymetry to create predictive models and maps of species density and biomass. I found that relationships with remotely sensed habitat variables are strong enough to create robust models. However, predictive maps at 10m resolution only gave a broad-scale picture of density distributions. Predictive maps consistently overpredicted species density, but often underpredicted peaks in density. Map resolution had a large effect on biomass predictions, where total predicted biomass was found to increase with increasing resolution. In conclusion, predictive maps seem to capture general patterns of species distributions; however, often peaks or hot spots in density are not captured. Predictive maps are very useful for understanding general patterns of species distributions, but one should be cautious when using them to obtain density of biomass estimates, especially when using estimates to inform management

Rancang Bangun Modul Portable Power Analizer Untuk Menganalisa Harmonisa

ABSTRACT Increasing of electrical power system containing harmonic current and voltage causes many serious effects involving worse power factor of the system, interference problem of telecommunication system, increasing of the system�s losses and many other problems of electronic tools. It causes ineffectively electrical energy. Engineering of portable power-analyzer module to analyze harmonic by evaluating the amount of harmonic signals�current and voltage signals is the aim of this final project. The instrument can be used to know about current and voltage THD value is fluke 41b power harmonic analyzer. This instrument has percentationof error about 1 %. The problem of this instrument is expensive price obout 13 million rupies, so for medium to low class is difficult to get it. So, distortion effect of non-sinusoidal signals caused non-linear loads can be evaluated. AT Mega 32 is one of microcontrollers having 10 bits resolution of internal ADC which can be able to convert current and voltage signals from analog to digital signals processed to be apart from the fundamental signal by Discrete Fourier Transform (DFT). Finally, information of the signal condition is displayed on graph LCD of G12864C. Based on the testing of this system wholly, showing the system works better, proven if compared with fluke 41B power harmonic analyzer. For example at practice with oscilloscope load, shown at the tool what me make, the voltage THD value is 4,2 % and the current THD value is 58,4 %. But at fluke 41B, shown the voltage THD value is 3,2 % and current THD is 59 %. So for difference average of voltage THD value is 1,8 % from thirteen times of practice with another load. And difference average of current THD value is 1,96 % from thirteen times of practice with another load. Key words: Harmonic, ADC, DFT, THD

Fault location and diagnosis in a medium voltage EPR power cable

This paper presents a case study on fault location, characterization and diagnosis in a length of shielded 11 kV medium voltage ethylene-propylene rubber (EPR) power cable. The defect was identified on-site as a low resistance fault occurring between the sheath and the core. A 43 m section was removed for further analysis. The fault resistance was characterized and the location of the defect pinpointed to within a few cm using a combination of time-difference-of-arrival location and infra-red imaging. A combination of X-ray computed tomography, scanning electron microscopy and energy dispersive X-ray spectroscopy were then applied to characterize any abnormalities in the dielectric surrounding the breakdown region. A significant number of high density contaminants were found to be embedded in the dielectric layer, having an average diameter of the order of 100 um, a maximum diameter of 310 um and an average density of 1 particle per 2.28 mm3 . Scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to determine the geometry and elemental composition of some initial contaminant samples. It was concluded that contamination of the EPR layer, combined with an observed eccentricity of the cable’s core and sheath resulting in a reduced insulation gap, may have led to an electric field concentration in the region of the defect sufficient to initiate breakdown. Preventative strategies are discussed for similar families of cables, including more stringent dielectric testing requirements at the manufacturing stage and PD monitoring to detect incipient failure

Design improvement of a 245-kV SF6 circuit breaker with double-speed mechanism through current zero analysis

This paper presents the results of current zero measurements during short-line fault interruption tests performed on three variants of an SF6 circuit breaker (CB) (245 kV, 40 kA) with a new mechanism for increasing the contact motion speed, shortly named double-speed mechanism, in order to distinguish between double-motion systems where both contacts are moving. The application of a double-speed mechanism provides the necessary increase of contact separation speed, without a significant increase of opening energy. Besides that, it does not requires any fixed mechanical connection between the stationary and moving contacts through the nozzle. This feature has a positive impact on the CB reliability and creates the possibility of easier assembly and dismantling of the interrupter from its insulator. High-resolution measurements of near current-zero arc current and voltage were carried out during these tests. Different levels of information on the "quality of interruption," obtained from current zero measurements are presented. Direct observation of arc current and arc voltage data are analyzed. The arc conductivity very shortly (500 and 200 ns) before current zero, as an indicator of the performance of the breaker under test is discussed. All information obtained during current zero measurement is in correlation with the direct results of testing and with design improvements in successive variants of the CB

One-step deposition of nano-to-micron-scalable, high-quality digital image correlation patterns for high-strain in-situ multi-microscopy testing

Digital Image Correlation (DIC) is of vital importance in the field of experimental mechanics, yet, producing suitable DIC patterns for demanding in-situ mechanical tests remains challenging, especially for ultra-fine patterns, despite the large number of patterning techniques in the literature. Therefore, we propose a simple, flexible, one-step technique (only requiring a conventional deposition machine) to obtain scalable, high-quality, robust DIC patterns, suitable for a range of microscopic techniques, by deposition of a low melting temperature solder alloy in so-called 'island growth' mode, without elevating the substrate temperature. Proof of principle is shown by (near-)room-temperature deposition of InSn patterns, yielding highly dense, homogeneous DIC patterns over large areas with a feature size that can be tuned from as small as 10nm to 2um and with control over the feature shape and density by changing the deposition parameters. Pattern optimization, in terms of feature size, density, and contrast, is demonstrated for imaging with atomic force microscopy, scanning electron microscopy (SEM), optical microscopy and profilometry. Moreover, the performance of the InSn DIC patterns and their robustness to large deformations is validated in two challenging case studies of in-situ micro-mechanical testing: (i) self-adaptive isogeometric digital height correlation of optical surface height profiles of a coarse, bimodal InSn pattern providing microscopic 3D deformation fields (illustrated for delamination of aluminum interconnects on a polyimide substrate) and (ii) DIC on SEM images of a much finer InSn pattern allowing quantification of high strains near fracture locations (illustrated for rupture of a Fe foil). As such, the high controllability, performance and scalability of the DIC patterns offers a promising step towards more routine DIC-based in-situ micro-mechanical testing.Comment: Accepted for publication in Strai

On Validating an Astrophysical Simulation Code

We present a case study of validating an astrophysical simulation code. Our study focuses on validating FLASH, a parallel, adaptive-mesh hydrodynamics code for studying the compressible, reactive flows found in many astrophysical environments. We describe the astrophysics problems of interest and the challenges associated with simulating these problems. We describe methodology and discuss solutions to difficulties encountered in verification and validation. We describe verification tests regularly administered to the code, present the results of new verification tests, and outline a method for testing general equations of state. We present the results of two validation tests in which we compared simulations to experimental data. The first is of a laser-driven shock propagating through a multi-layer target, a configuration subject to both Rayleigh-Taylor and Richtmyer-Meshkov instabilities. The second test is a classic Rayleigh-Taylor instability, where a heavy fluid is supported against the force of gravity by a light fluid. Our simulations of the multi-layer target experiments showed good agreement with the experimental results, but our simulations of the Rayleigh-Taylor instability did not agree well with the experimental results. We discuss our findings and present results of additional simulations undertaken to further investigate the Rayleigh-Taylor instability.Comment: 76 pages, 26 figures (3 color), Accepted for publication in the ApJ