951 research outputs found

    Terahertz Security Image Quality Assessment by No-reference Model Observers

    Full text link
    To provide the possibility of developing objective image quality assessment (IQA) algorithms for THz security images, we constructed the THz security image database (THSID) including a total of 181 THz security images with the resolution of 127*380. The main distortion types in THz security images were first analyzed for the design of subjective evaluation criteria to acquire the mean opinion scores. Subsequently, the existing no-reference IQA algorithms, which were 5 opinion-aware approaches viz., NFERM, GMLF, DIIVINE, BRISQUE and BLIINDS2, and 8 opinion-unaware approaches viz., QAC, SISBLIM, NIQE, FISBLIM, CPBD, S3 and Fish_bb, were executed for the evaluation of the THz security image quality. The statistical results demonstrated the superiority of Fish_bb over the other testing IQA approaches for assessing the THz image quality with PLCC (SROCC) values of 0.8925 (-0.8706), and with RMSE value of 0.3993. The linear regression analysis and Bland-Altman plot further verified that the Fish__bb could substitute for the subjective IQA. Nonetheless, for the classification of THz security images, we tended to use S3 as a criterion for ranking THz security image grades because of the relatively low false positive rate in classifying bad THz image quality into acceptable category (24.69%). Interestingly, due to the specific property of THz image, the average pixel intensity gave the best performance than the above complicated IQA algorithms, with the PLCC, SROCC and RMSE of 0.9001, -0.8800 and 0.3857, respectively. This study will help the users such as researchers or security staffs to obtain the THz security images of good quality. Currently, our research group is attempting to make this research more comprehensive.Comment: 13 pages, 8 figures, 4 table

    Estimating black hole masses of blazars

    Full text link
    Estimating black hole masses of blazars is still a big challenge. Because of the contamination of jets, using the previously suggested size -- continuum luminosity relation can overestimate the broad line region (BLR) size and black hole mass for radio-loud AGNs, including blazars. We propose a new relation between the BLR size and HβH_{\beta} emission line luminosity and present evidences for using it to get more accurate black hole masses of radio-loud AGNs. For extremely radio-loud AGNs such as blazars with weak/absent emission lines, we suggest to use the fundamental plane relation of their elliptical host galaxies to estimate the central velocity dispersions and black hole masses, if their velocity dispersions are not known but the host galaxies can be mapped. The black hole masses of some well-known blazars, such as OJ 287, AO 0235+164 and 3C 66B, are obtained using these two methods and the M - σ\sigma relation. The implications of their black hole masses on other related studies are also discussed.Comment: 7 pages, invited talk presented in the workshop on Multiwavelength Variability of Blazars (Guangzhou, China, Sept. 22-24, 2010). To be published in the Journal of Astrophysics and Astronom

    Inexpensive method for producing macroporous silicon particulates (MPSPs) with pyrolyzed polyacrylonitrile for lithium ion batteries

    Get PDF
    One of the most exciting areas in lithium ion batteries is engineering structured silicon anodes. These new materials promise to lead the next generation of batteries with significantly higher reversible charge capacity than current technologies. One drawback of these materials is that their production involves costly processing steps, limiting their application in commercial lithium ion batteries. In this report we present an inexpensive method for synthesizing macroporous silicon particulates (MPSPs). After being mixed with polyacrylonitrile (PAN) and pyrolyzed, MPSPs can alloy with lithium, resulting in capacities of 1000 mAhg−1 for over 600+ cycles. These sponge-like MPSPs with pyrolyzed PAN (PPAN) can accommodate the large volume expansion associated with silicon lithiation. This performance combined with low cost processing yields a competitive anode material that will have an immediate and direct application in lithium ion batteries

    The effect of a preparation of minerals, vitamins and trace elements on the cardiac gene expression pattern in male diabetic rats

    Get PDF
    BACKGROUND: Diabetic patients have an increased risk of developing cardiovascular diseases, which are the leading cause of death in developed countries. Although multivitamin products are widely used as dietary supplements, the effects of these products have not been investigated in the diabetic heart yet. Therefore, here we investigated if a preparation of different minerals, vitamins, and trace elements (MVT) affects the cardiac gene expression pattern in experimental diabetes. METHODS: Two-day old male Wistar rats were injected with streptozotocin (i.p. 100 mg/kg) or citrate buffer to induce diabetes. From weeks 4 to 12, rats were fed with a vehicle or a MVT preparation. Fasting blood glucose measurement and oral glucose tolerance test were performed at week 12, and then total RNA was isolated from the myocardium and assayed by rat oligonucleotide microarray for 41012 oligonucleotides. RESULTS: Significantly elevated fasting blood glucose concentration and impaired glucose tolerance were markedly improved by MVT-treatment in diabetic rats at week 12. Genes with significantly altered expression due to diabetes include functional clusters related to cardiac hypertrophy (e.g. caspase recruitment domain family, member 9; cytochrome P450, family 26, subfamily B, polypeptide; FXYD domain containing ion transport regulator 3), stress response (e.g. metallothionein 1a; metallothionein 2a; interleukin-6 receptor; heme oxygenase (decycling) 1; and glutathione S-transferase, theta 3), and hormones associated with insulin resistance (e.g. resistin; FK506 binding protein 5; galanin/GMAP prepropeptide). Moreover the expression of some other genes with no definite cardiac function was also changed such as e.g. similar to apolipoprotein L2; brain expressed X-linked 1; prostaglandin b2 synthase (brain). MVT-treatment in diabetic rats showed opposite gene expression changes in the cases of 19 genes associated with diabetic cardiomyopathy. In healthy hearts, MVT-treatment resulted in cardiac gene expression changes mostly related to immune response (e.g. complement factor B; complement component 4a; interferon regulatory factor 7; hepcidin). CONCLUSIONS: MVT-treatment improved diagnostic markers of diabetes. This is the first demonstration that MVT-treatment significantly alters cardiac gene expression profile in both control and diabetic rats. Our results and further studies exploring the mechanistic role of individual genes may contribute to the prevention or diagnosis of cardiac complications in diabetes

    Mitochondrial DNA Evidence for a Diversified Origin of Workers Building Mausoleum for First Emperor of China

    Get PDF
    Variant studies on ancient DNA have attempted to reveal individual origin. Here, based on cloning sequencing and polymerase chain reaction-restriction fragment length polymorphisms, we analyzed polymorphisms in the first hypervariable region and coding regions of mitochondrial DNA of 19 human bone remains which were excavated from a tomb near the Terra Cotta Warriors and dated some 2,200 years before present. With the aim of shedding light on origins of these samples who were supposed to be workers building the mausoleum for the First Emperor of China, we compared them with 2,164 mtDNA profiles from 32 contemporary Chinese populations at both population and individual levels. Our results showed that mausoleum-building workers may be derived from very diverse sources of origin

    Toxicity of Sediment-Associated Pesticides to Chironomus dilutus and Hyalella azteca

    Get PDF
    Two hundred sediment samples were collected and their toxicity evaluated to aquatic species in a previous study in the agriculturally dominated Central Valley of California, United States. Pyrethroid insecticides were the main contributors to the observed toxicity. However, mortality in approximately one third of the toxic samples could not be explained solely by the presence of pyrethroids in the matrices. Hundreds of pesticides are currently used in the Central Valley of California, but only a few dozen are analyzed in standard environmental monitoring. A significant amount of unexplained sediment toxicity may be due to pesticides that are in widespread use that but have not been routinely monitored in the environment, and even if some of them were, the concentrations harmful to aquatic organisms are unknown. In this study, toxicity thresholds for nine sediment-associated pesticides including abamectin, diazinon, dicofol, fenpropathrin, indoxacarb, methyl parathion, oxyfluorfen, propargite, and pyraclostrobin were established for two aquatic species, the midge Chironomus dilutus and the amphipod Hyalella azteca. For midges, the median lethal concentration (LC50) of the pesticides ranged from 0.18 to 964 μg/g organic carbon (OC), with abamectin being the most toxic and propargite being the least toxic pesticide. A sublethal growth endpoint using average individual ash-free dry mass was also measured for the midges. The no–observable effect concentration values for growth ranged from 0.10 to 633 μg/g OC for the nine pesticides. For the amphipods, fenpropathrin was the most toxic, with an LC50 of 1–2 μg/g OC. Abamectin, diazinon, and methyl parathion were all moderately toxic (LC50s 2.8–26 μg/g OC). Dicofol, indoxacarb, oxyfluorfen, propargite, and pyraclostrobin were all relatively nontoxic, with LC50s greater than the highest concentrations tested. The toxicity information collected in the present study will be helpful in decreasing the frequency of unexplained sediment toxicity in agricultural waterways

    Computational investigation of diesel nozzle internal flow during the complete injection event

    Full text link
    [EN] Currently, diesel engines are calibrated using more and more complex multiple injection strategies. Under these conditions, the characteristics of the flow exiting the fuel injector are strongly affected by the transient interaction between the needle, the sac volume and the orifices, which are not yet clear. In the current paper, a methodology combining a 1D injector model and 3D-CFD simulations is proposed. First, the characteristics of the nozzle flow have been experimentally assessed in transient conditions by means of injection rate and momentum flux measurements. Later, the 3D-CFD modeling approach has been validated at steady-state fixed lift conditions. Finally, a previously developed 1D injector model has been used to extract the needle lift profiles and transient pressure boundary conditions used for the full-transient 3D-CFD simulations, using adaptive mesh refinement (AMR) strategies to be able to simulate the complete injection rate starting from 1 mu m lift.This work was partly sponsored by "Ministerio de Economia y Competitividad'', of the Spanish Government, in the frame of the Project "Estudio de la interaccion chorro-pared en condiciones realistas de motor'', Reference TRA2015-67679-c2-1-R. The authors would like also to thank the computer resources, technical expertise and assistance provided by Universidad de Valencia in the use of the supercomputer "Tirant''. Mr. Jaramillo's Thesis is funded by "Conselleria d'Educacio, Cultura i Esports'' of Generalitat Valenciana in the frame of the program "Programa VALI + D para investigadores en formacion, Reference ACIF/2015/040.Salvador, FJ.; De La Morena, J.; Bracho Leon, G.; Jaramillo-Císcar, D. (2018). Computational investigation of diesel nozzle internal flow during the complete injection event. Journal of the Brazilian Society of Mechanical Sciences and Engineering. 40(3):153-167. https://doi.org/10.1007/s40430-018-1074-zS153167403Hall CAS, Lambert JG, Balogh SB (2014) EROI of different fuels and the implications for society. Energy Policy 64:141–152. https://doi.org/10.1016/j.enpol.2013.05.049Lujan JM, Tormos B, Salvador FJ, Gargar K (2009) Comparative analysis of a DI diesel engine fuelled with biodiesel blends during the European MVEG-A cycle: preliminary study (I). Biomass Bioenergy 33:941–947. https://doi.org/10.1016/j.biombioe.2009.02.004Pickett LM, Siebers DL (2004) Soot in diesel fuel jets: effects of ambient temperature, ambient density, and injection pressure. Combust Flame 138:114–135. https://doi.org/10.1016/j.combustflame.2004.04.006Dec JE (1997) A Conceptual Model of DI Diesel Combustion Based on Laser-Sheet Imaging. SAE Tech. Pap. 970873Wang X, Huang Z, Zhang W et al (2011) Effects of ultra-high injection pressure and micro-hole nozzle on flame structure and soot formation of impinging diesel spray. Appl Energy 88:1620–1628. https://doi.org/10.1016/j.apenergy.2010.11.035Sayin C, Gumus M, Canakci M (2013) Influence of injector hole number on the performance and emissions of a di diesel engine fueled with biodiesel-diesel fuel blends. Appl Therm Eng 61:121–128. https://doi.org/10.1016/j.applthermaleng.2013.07.038Mohan B, Yang W, Chou SK (2013) Fuel injection strategies for performance improvement and emissions reduction in compression ignition engines—A review. Renew Sustain Energy Rev 28:664–676. https://doi.org/10.1016/j.rser.2013.08.051Payri R, Salvador FJ, Gimeno J, De la Morena J (2011) Influence of injector technology on injection and combustion development, Part 1: hydraulic characterization. Appl Energy 88:1068–1074. https://doi.org/10.1016/j.apenergy.2010.10.012Park SW, Kim JW, Lee CS (2006) Effect of injector type on fuel-air mixture formation of high-speed diesel sprays. Proc Inst Mech Eng D 220:647–659. https://doi.org/10.1243/09544070D20304Moon S, Komada K, Sato K et al (2015) Ultrafast X-ray study of multi-hole GDI injector sprays: effects of nozzle hole length and number on initial spray formation. Exp Therm Fluid Sci 68:68–81. https://doi.org/10.1016/j.expthermflusci.2015.03.027Powell CF, Kastengren AL, Liu Z, Fezzaa K (2010) The effects of diesel injector needle motion on spray structure. J Eng Gas Turbines Power 133:12802. https://doi.org/10.1115/1.4001073Huang W, Moon S, Ohsawa K (2016) Near-nozzle dynamics of diesel spray under varied needle lifts and its prediction using analytical model. Fuel 180:292–300. https://doi.org/10.1016/j.fuel.2016.04.042Sun Z-Y, Li G-X, Chen C et al (2015) Numerical investigation on effects of nozzle’s geometric parameters on the flow and the cavitation characteristics within injector’s nozzle for a high-pressure common-rail DI diesel engine. Energy Convers Manag 89:843–861. https://doi.org/10.1016/j.enconman.2014.10.047Devassy BM, Habchi C, Daniel E (2015) Atomization modelling of liquid jets using a two-surface density approach. At Sprays 25:47–80Moon S, Gao Y, Park S et al (2015) Effect of the number and position of nozzle holes on in- and near-nozzle dynamic characteristics of diesel injection. Fuel 150:112–122. https://doi.org/10.1016/j.fuel.2015.01.097Payri R, Salvador FJ, Carreres M, De la Morena J (2016) Fuel temperature influence on the performance of a last generation common-rail diesel ballistic injector. Part II: 1D model development, validation and analysis. Energy Convers Manag 114:376–391. https://doi.org/10.1016/j.enconman.2016.02.043Plamondon E, Seers P (2014) Development of a simplified dynamic model for a piezoelectric injector using multiple injection strategies with biodiesel/diesel-fuel blends. Appl Energy 131:411–424. https://doi.org/10.1016/j.apenergy.2014.06.039Postrioti L, Malaguti S, Bosi M et al (2014) Experimental and numerical characterization of a direct solenoid actuation injector for diesel engine applications. Fuel 118:316–328. https://doi.org/10.1016/j.fuel.2013.11.001Desantes JM, Salvador FJ, Lopez JJ, De la Morena J (2011) Study of mass and momentum transfer in diesel sprays based on X-ray mass distribution measurements and on a theoretical derivation. Exp Fluids 50:233–246. https://doi.org/10.1007/s00348-010-0919-8De la Morena J, Neroorkar K, Plazas AH et al (2013) Numerical analysis of the influence of diesel nozzle design on internal flow characteristics for 2-valve diesel engine application. At Sprays 23:97–118. https://doi.org/10.1615/AtomizSpr.2013006361Duke DJ, Schmidt DP, Neroorkar K et al (2013) High-resolution large eddy simulations of cavitating gasoline-ethanol blends. Int J Engine Res 14:578–589. https://doi.org/10.1177/1468087413501824Mitroglou N, McLorn M, Gavaises M et al (2014) Instantaneous and ensemble average cavitation structures in diesel micro-channel flow orifices. Fuel 116:736–742. https://doi.org/10.1016/j.fuel.2013.08.060Wang X, Li K, Su W (2012) Experimental and numerical investigations on internal flow characteristics of diesel nozzle under real fuel injection conditions. Exp Therm Fluid Sci 42:204–211. https://doi.org/10.1016/j.expthermflusci.2012.04.022Sou A, Pratama RH (2016) Effects of asymmetric inflow on cavitation in fuel injector and discharged liquid jet. At Sprays 26:939–959. https://doi.org/10.1615/AtomizSpr.2015013501Xue Q, Battistoni M, Powell CF et al (2015) An Eulerian CFD model and X-ray radiography for coupled nozzle flow and spray in internal combustion engines. Int J Multiph Flow 70:77–88. https://doi.org/10.1016/j.ijmultiphaseflow.2014.11.012Castilla R, Gamez-Montero PJ, Ertrk N et al (2010) Numerical simulation of turbulent flow in the suction chamber of a gearpump using deforming mesh and mesh replacement. Int J Mech Sci 52:1334–1342. https://doi.org/10.1016/j.ijmecsci.2010.06.009Parlak Z, Engin T (2012) Time-dependent CFD and quasi-static analysis of magnetorheological fluid dampers with experimental validation. Int J Mech Sci 64:22–31. https://doi.org/10.1016/j.ijmecsci.2012.08.006Chiatti G, Chiavola O, Palmieri F (2009) Spray modeling for diesel engine performance analysis. SAE Tech Pap 2009-01-0835. https://doi.org/10.4271/2009-01-0835Marcer R, Audiffren C, Viel A, et al (2010) Coupling 1D system AMESim and 3D CFD EOLE models for diesel injection simulation Renault. In: ILASS—Eur. 2010, 23rd Annu. Conf. Liq. At. Spray Syst., pp 1–10Desantes JM, Salvador FJ, Carreres M, Martínez-López J (2014) Large-eddy simulation analysis of the influence of the needle lift on the cavitation in diesel injector nozzles. Proc Inst Mech Eng D 229:407–423. https://doi.org/10.1177/0954407014542627Battistoni M, Xue Q, Som S (2016) Large-eddy simulation (LES) of spray transients: start and end of injection phenomena. Oil Gas Sci Technol 71:24. https://doi.org/10.2516/ogst/2015024CONVERGE is a trade mark of convergent science. https://convergecfd.comMacian V, Bermúdez V, Payri R, Gimeno J (2003) New technique for determination of internal geometry of a diesel nozzle with the use of silicone methodology. Exp Tech 27:39–43. https://doi.org/10.1111/j.1747-1567.2003.tb00107.xDabiri S, Sirignano WA, Joseph DD (2007) Cavitation in an orifice flow. Phys Fluids 19:72112. https://doi.org/10.1063/1.2750655Mohan B, Yang W, Chou SK (2014) Cavitation in injector nozzle holes—a parametric study. Eng Appl Comput Fluid Mech 8:70–81Salvador FJ, Hoyas S, Novella R, Martinez-Lopez J (2011) Numerical simulation and extended validation of two-phase compressible flow in diesel injector nozzles. Proc Inst Mech Eng D 225:545–563. https://doi.org/10.1177/09544070JAUTO1569Som S, Longman DE, Ramirez AI, Aggarwal S (2012) Influence of nozzle orifice geometry and fuel properties on flow and cavitation characteristics of a diesel injector. In: Fuel Inject. Automot. Eng., pp 112–126Desantes JM, Salvador FJ, Carreres M, Jaramillo D (2015) Experimental characterization of the thermodynamic properties of diesel fuels over a wide range of pressures and temperatures. SAE Int J Fuels Lubr 8:2015-01-0951. https://doi.org/10.4271/2015-01-0951Bosch W (1966) The fuel rate indicator: a new measuring instrument for display of the characteristics of individual injection. SAE Pap. 660749Payri R, Salvador FJ, Gimeno J, Bracho G (2008) A new methodology for correcting the signal cumulative phenomenon on injection rate measurements. Exp Tech 32:46–49. https://doi.org/10.1111/j.1747-1567.2007.00188.xPayri F, Payri R, Salvador FJ, Martínez-López J (2011) A contribution to the understanding of cavitation effects in diesel injector nozzles through a combined experimental and computational investigation. Comput Fluids 58:88–101. https://doi.org/10.1016/j.compfluid.2012.01.005Lichtarowicz AK, Duggins RK, Markland E (1965) Discharge coefficients for incompressible non-cavitating flow through long orifices. J Mech Eng Sci 7:210–219. https://doi.org/10.1243/JMES_JOUR_1965_007_029_02Lopez JJ, Salvador FJ, De la Garza OA, Arrègle J (2012) Characterization of the pressure losses in a common rail diesel injector. Proc Inst Mech Eng D 226:1697–1706. https://doi.org/10.1177/0954407012447020Salvador FJ, Carreres M, Jaramillo D, Martínez-López J (2015) Comparison of microsac and VCO diesel injector nozzles in terms of internal nozzle flow characteristics. Energy Convers Manag 103:284–299. https://doi.org/10.1016/j.enconman.2015.05.062LMS (2010) Imagine.Lab AMESim v.10. User’s manualPayri R, Salvador FJ, Martí-Aldaraví P, Martínez-López J (2012) Using one-dimensional modeling to analyze the influence of the use of biodiesels on the dynamic behavior of solenoid-operated injectors in common rail systems: detailed injection system model. Energy Convers Manag 54:90–99. https://doi.org/10.1016/j.enconman.2011.10.00

    Spatial patterns of mercury in biota of Adirondack, New York lakes

    Get PDF
    We studied the spatial distribution patterns of mercury (Hg) in lake water, littoral sediments, zooplankton, crayfish, fish, and common loons in 44 lakes of the Adirondacks of New York State, USA, a region that has been characterized as a “biological Hg hotspot”. Our study confirmed this pattern, finding that a substantial fraction of the lakes studied had fish and loon samples exceeding established criteria for human and wildlife health. Factors accounting for the spatial variability of Hg in lake water and biota were lake chemistry (pH, acid neutralizing capacity (ANC), percent carbon in sediments), biology (taxa presence, trophic status) and landscape characteristics (land cover class, lake elevation). Hg concentrations in zooplankton, fish and common loons were negatively associated with the lake water acid-base status (pH, ANC). Bioaccumulation factors (BAF) for methyl Hg (MeHg) increased from crayfish (mean log10 BAF = 5.7), to zooplankton (5.9), to prey fish (6.2), to larger fish (6.3), to common loons (7.2). MeHg BAF values in zooplankton, crayfish, and fish (yellow perch equivalent) all increased with increasing lake elevation. Our findings support the hypothesis that bioaccumulation of MeHg at the base of the food chain is an important controller of Hg concentrations in taxa at higher trophic levels. The characteristics of Adirondack lake-watersheds (sensitivity to acidic deposition; significant forest and wetland land cover; and low nutrient inputs) contribute to elevated Hg concentrations in aquatic biota
    corecore