Design and Analysis of a Disk-oriented Engine Combustor

In a novel approach to gas-turbine power production, an engine was designed and analyzed to use both a single-stage centrifugal compressor and single-stage radial in- ow turbine configured back-to-back. This air path reduced the axial length of the engine up to 60%, providing additional modularity in a gas-turbine engine that could be used to improve mobility of ground-based power units or increase the survivability of aircraft through the use of distributive propulsion. This increased modularity was made possible by the use of a circumferential ow combustor that substantially decreased the axial length of the burner and negated the need to return compressor radial ow to the axial direction, as found in conventional combustion approaches. The Disk-Oriented Engine was designed to incorporate swirling inlet ow from a centrifugal compressor and exhaust directly into a radial in-ow turbine, while still maintaining the initial swirl pattern out of the compressor. The configuration of the combustion cavity was evaluated through computational fluid dynamics. An iterative design approach was used to achieve desired ow characteristics and combustion dynamics through geometry shaping and placement of air supply holes. The result of this design process was a computational combustor model that accepted swirling inlet ow, dispersed that air and fuel about a unique u-bend circumferential combustion cavity, and exhausted in the radial direction to feed a radial in-ow turbine. Sustained combustion was simulated at design conditions with a 3% total pressure loss in the combustor and a turbine inlet pattern factor of 0.24, indicating that such a design could operate as a gas-turbine engine, while reducing axial length up to 60% compared to traditional systems of similar size and performance. Computational results were compared to experimental tests on fuel-air swirl injectors, providing qualitative and quantitative insight into the stability of the flame anchoring system. From this design, a full-scale physical model of the Disk-Oriented Engine Combustor was designed and built for combustion analysis and characterization

Baseline characterization of nearshore Rocky reef fishes found in northern California marine protected areas

The nearshore rocky reef habitat along California’s North Coast supports a diverse assemblage of ecologically, economically, and culturally important fishes. In December 2012, a network of Marine Protected Areas (MPAs) was established in Northern California with the goal of protecting these species. Our study utilized collaborative hook and line fishing methods, while employing local charter fishing vessels, to establish a baseline of rocky reef fishes associated with four MPAs and four unprotected reference sites. These baseline data were then used to inform generalized additive models (GAMs) to explore potential drivers of relative abundance, size, and diversity of fishes. Understanding what factors drive initial conditions in paired sites will allow managers to track fluctuations in fish communities associated with rocky reefs, and properly attribute changes to MPA effects over time. This is especially important in the Pyramid Point and Sea Lion Gulch MPAs, where catch per unity effort was significantly different from their associated reference sites. These differences are likely a function of different levels of historical fishing pressure between MPAs and reference sites. Distance from port, a proxy for historical fishing pressure, and depth, were the most important predictors of fish catch per unit effort and diversity in the North Coast MPA Region. Continued monitoring of MPAs in the North Coast region will be critical in the evaluation of MPA effects and provide much needed fishery-independent data that can be used to improve management strategies in this area

Evolution and Modern Approaches for Thermal Analysis of Electrical Machines

In this paper, the authors present an extended survey on the evolution and the modern approaches in the thermal analysis of electrical machines. The improvements and the new techniques proposed in the last decade are analyzed in depth and compared in order to highlight the qualities and defects of each. In particular, thermal analysis based on lumped-parameter thermal network, finite-element analysis, and computational fluid dynamics are considered in this paper. In addition, an overview of the problems linked to the thermal parameter determination and computation is proposed and discussed. Taking into account the aims of this paper, a detailed list of books and papers is reported in the references to help researchers interested in these topics

Electronic compensation for reflector surface distortion to improve radiation pattern characteristics of antennas

A simple procedure is described for determining the excitation coefficients of an array feed which compensates for the surface distortion of a reflector antenna to improve the radiation pattern in such a way as to approximate the performance of the undistorted antenna. A computer simulation for a practical feed array is presented as an example of compensation for the distortion of an actual antenna

A Computationally Efficient Method for Calculation of Strand Eddy Current Losses in Electric Machines

In this paper, a fast finite element (FE)-based method for the calculation of eddy current losses in the stator windings of randomly wound electric machines with a focus on fractional slot concentrated winding (FSCW) permanent magnet (PM) machines will be presented. The method is particularly suitable for implementation in large-scale design optimization algorithms where a qualitative characterization of such losses at higher speeds is most beneficial for identification of the design solutions which exhibit the lowest overall losses including the ac losses in the stator windings. Unlike the common practice of assuming a constant slot fill factor, sf, for all the design variations, the maximum sf in the developed method is determined based on the individual slot structure/dimensions and strand wire specifications. Furthermore, in lieu of detailed modeling of the conductor strands in the initial FE model, which significantly adds to the complexity of the problem, an alternative rectangular coil modeling subject to a subsequent flux mapping technique for determination of the impinging flux on each individual strand is pursued. The research focus of the paper is placed on development of a computationally efficient technique for the ac winding loss derivation applicable in design-optimization, where both the electromagnetic and thermal machine behavior are accounted for. The analysis is supplemented with an investigation on the influence of the electrical loading on ac winging loss effects for a particular machine design, a subject which has received less attention in the literature. Experimental ac loss measurements on a 12-slot 10-pole stator assembly will be discussed to verify the existing trends in the simulation results

Computationally Efficient Strand Eddy Current Loss Calculation in Electric Machines

A fast finite element (FE) based method for the calculation of eddy current losses in the stator windings of randomly wound electric machines is presented in this paper. The method is particularly suitable for implementation in large-scale design optimization algorithms where a qualitative characterization of such losses at higher speeds is most beneficial for identification of the design solutions that exhibit the lowest overall losses including the ac losses in the stator windings. Unlike the common practice of assuming a constant slot fill factor s f for all the design variations, the maximum s f in the developed method is determined based on the individual slot structure/dimensions and strand wire specifications. Furthermore, in lieu of detailed modeling of the conductor strands in the initial FE model, which significantly adds to the complexity of the problem, an alternative rectangular coil modeling subject to a subsequent flux mapping technique for determination of the impinging flux on each individual strand is pursued. Rather than pursuing the precise estimation of ac conductor losses, the research focus of this paper is placed on the development of a computationally efficient technique for the derivation of strand eddy current losses applicable in design optimization, especially where both the electromagnetic and thermal machine behavior are accounted for. A fractional-slot concentrated winding permanent magnet synchronous machine is used for the purpose of this study due to the higher slot leakage flux and slot opening fringing flux of such machines, which are the major contributors to strand eddy current losses in the windings. The analysis is supplemented with an investigation on the influence of the electrical loading on ac winding loss effects for this machine design, a subject that has received less attention in the literature. Experimental ac loss measurements on a 12-slot 10-pole stator assembly will be discussed to verify the existing trends in the simulation result

A thin layer angiogenesis assay: a modified basement matrix assay for assessment of endothelial cell differentiation

BACKGROUND: Basement matrices such as Matrigel™ and Geltrex™ are used in a variety of cell culture assays of anchorage-dependent differentiation including endothelial cell tube formation assays. The volumes of matrix recommended for these assays (approximately 150 μl/cm(2)) are costly, limit working distances for microscopy, and require cell detachment for subsequent molecular analysis. Here we describe the development and validation of a thin-layer angiogenesis (TLA) assay for assessing the angiogenic potential of endothelial cells that overcomes these limitations. RESULTS: Geltrex™ basement matrix at 5 μl/cm(2) in 24-well (10 μl) or 96-well (2 μl) plates supports endothelial cell differentiation into tube-like structures in a comparable manner to the standard larger volumes of matrix. Since working distances are reduced, high-resolution single cell microscopy, including DIC and confocal imaging, can be used readily. Using MitoTracker dye we now demonstrate, for the first time, live mitochondrial dynamics and visualise the 3-dimensional network of mitochondria present in differentiated endothelial cells. Using a standard commercial total RNA extraction kit (Qiagen) we also show direct RNA extraction and RT-qPCR from differentiated endothelial cells without the need to initially detach cells from their supporting matrix. CONCLUSIONS: We present here a new thin-layer assay (TLA) for measuring the anchorage-dependent differentiation of endothelial cells into tube-like structures which retains all the characteristics of the traditional approach but with the added benefit of a greatly lowered cost and better compatibility with other techniques, including RT-qPCR and high-resolution microscopy. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12860-014-0041-5) contains supplementary material, which is available to authorized users

Transforming growth factor-beta and endoglin signaling orchestrate wound healing

Physiological wound healing is a complex process requiring the temporal and spatial co-ordination of various signaling networks, biomechanical forces, and biochemical signaling pathways in both hypoxic and non-hypoxic conditions. Although a plethora of factors are required for successful physiological tissue repair, transforming growth factor beta (TGF-β) expression has been demonstrated throughout wound healing and shown to regulate many processes involved in tissue repair, including production of ECM, proteases, protease inhibitors, migration, chemotaxis, and proliferation of macrophages, fibroblasts of the granulation tissue, epithelial and capillary endothelial cells. TGF-β mediates these effects by stimulating signaling pathways through a receptor complex which contains Endoglin. Endoglin is expressed in a broad spectrum of proliferating and stem cells with elevated expression during hypoxia, and regulates important cellular functions such as proliferation and adhesion via Smad signaling. This review focuses on how the TGF-β family and Endoglin, regulate stem cell availability, and modulate cellular behavior within the wound microenvironment, includes current knowledge of the signaling pathways involved, and explores how this information may be applicable to inflammatory and/or angiogenic diseases such as fibrosis, rheumatoid arthritis and metastatic cancer

Physiological Ecology of Four Endemic Alabama Species and the Exotic Asiatic Weatherfish, \u3ci\u3eMisgurnus anguillicaudatus\u3c/i\u3e (Cantor, 1842)

The occurrence of Asiatic Weatherfish, Misgurnus anguillicaudatus, in Alabama, a state known for its rich biodiversity, has generated concern among conservation managers. The current study used respirometry techniques to investigate the effects of increasing temperature on four native southeastern fishes (one cyprinid, two percids, and one elassomid) and the non-native M. anguillicaudatus. A minimum of five individuals of each species were used, and three experimental temperatures were chosen to represent spring and summer averages of northeast Alabama streams (15, 20, and 25°C). Overall, mean standard metabolic rates (SMRs) for M. anguillicaudatus were low (97.01, 127.75, and 158.50 mg O2 kg-1h-1 at 15, 20, and 25°C, respectively); M. anguillicaudatus was the only species for which SMR did not significantly increase with temperature (p = 0.467). In contrast, mean SMRs for all native species examined were higher than M. anguillicaudatus rates at a given temperature, and mean SMRs for Cyprinella caerulea, Etheostoma brevirostrum, and Etheostoma ditrema exhibited significant increases in SMR when temperatures were increased (e.g. 403.46, 704.42, and 1150.03 mg O2 kg-1h-1 at 25°C, respectively) (p \u3c 0.01). Elassoma zonatum displayed highly significant increases in SMR when temperature increased from 15-20°C (p \u3c 0.001). Overall, the abiotic tolerances of M. anguillicaudatus may facilitate further establishment that could lead to negative impacts on native species