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Sample records for surface energy difference

  1. Electrostatic energy and screened charge interaction near the surface of metals with different Fermi surface shape

    Science.gov (United States)

    Gabovich, A. M.; Il'chenko, L. G.; Pashitskii, E. A.; Romanov, Yu. A.

    1980-04-01

    Using the Poisson equation Green function for a self-consistent field in a spatially inhomogeneous system, expressions for the electrostatic energy and screened charge interaction near the surface of a semi-infinite metal and a thin quantizing film are derived. It is shown that the decrease law and Friedel oscillation amplitude of adsorbed atom indirect interaction are determined by the electron spectrum character and the Fermi surface shape. The results obtained enable us to explain, in particular, the submonolayer adsorbed film structure on the W and Mo surfaces.

  2. Surface free energy of polypropylene and polycarbonate solidifying at different solid surfaces

    International Nuclear Information System (INIS)

    Chibowski, Emil; Terpilowski, Konrad

    2009-01-01

    Advancing and receding contact angles of water, formamide, glycerol and diiodomethane were measured on polypropylene (PP) and polycarbonate (PC) sample surfaces which solidified at Teflon, glass or stainless steel as matrix surfaces. Then from the contact angle hystereses (CAH) the apparent free energies γ s tot of the surfaces were evaluated. The original PP surface is practically nonpolar, possessing small electron donor interaction (γ s - =1.91mJ/m 2 ), as determined from the advancing contact angles of these liquids. It may result from impurities of the polymerization process. However, it increases up to 8-10 mJ/m 2 for PP surfaces contacted with the solids. The PC surfaces both original and modified show practically the same γ s - =6.56.7mJ/m 2 . No electron acceptor interaction is found on the surfaces. The γ s tot of modified PP and PC surfaces depend on the kind of probe liquid and contacted solid surface. The modified PP γ s tot values determined from CAH of polar liquids are greater than that of original surface and they increase in the sequence: Teflon, glass, stainless steel surface, at which they solidified. No clear dependence is observed between γ s tot and dielectric constant or dipole moment of the polar probe liquids. The changes in γ s tot of the polymer surfaces are due to the polymer nature and changes in its surface structure caused by the structure and force field of the contacting solid. It has been confirmed by AFM images.

  3. SCANNING ELECTRON-MICROSCOPIC EVALUATION OF THE FRACTURED SURFACES OF CANINE CALCULI FROM SUBSTRATA WITH DIFFERENT SURFACE FREE-ENERGY

    NARCIS (Netherlands)

    UYEN, HMW; JONGEBLOED, WL; BUSSCHER, HJ

    1991-01-01

    The strength of adhesion between dental calculus and enamel or dentin surfaces determines the ease with which the calculus can be removed by brushing or professional dental treatment. In this study, we examined the adhesion of canine calculi formed on substrata with different surface free energies

  4. Effect of Collagen Matrix Saturation on the Surface Free Energy of Dentin using Different Agents.

    Science.gov (United States)

    de Almeida, Leopoldina de Fátima Dantas; Souza, Samilly Evangelista; Sampaio, Aline Araújo; Cavalcanti, Yuri Wanderley; da Silva, Wander José; Del Bel Cur, Altair A; Hebling, Josimeri

    2015-07-01

    The surface free energy of conditioned-dentin is one of the factors that interfere with monomeric infiltration of the interfibrillar spaces. Saturation of the tooth matrix with different substances may modulate this energy and, consequently, the wettability of the dentin. To evaluate the influence of different substances used to saturate conditioned-dentin on surface free energy (SFE) of this substrate. Dentin blocks (4 × 7 × 1 mm, n = 6/ group), obtained from the roots of bovine incisors, were etched using phosphoric acid for 15 seconds, rinsed and gently dried. The surfaces were treated for 60 seconds with: ultra-purified water (H20-control); ethanol (EtOH), acetone (ACT), chlorhexidine (CHX), ethylenediaminetetraacetic acid (EDTA); or sodium hypochlorite (NaOCl). The tooth surfaces were once again dried with absorbent paper and prepared for SFE evaluation using three standards: water, formamide and bromonaphthalene. Analysis of variance (ANOVA) and Dunnet's tests (a = 0.05) were applied to the data. Ethylenediaminetetraacetic acid was the only substance that caused a change to the contact angle for the standards water and formamide, while only EtOH influenced the angles formed between formamide and the dentin surface. None of the substances exerted a significant effect for bromonaphtha-lene. In comparison to the control, only EDTA and NaOCl altered both polar components of the SFE. Total SFE was increased by saturation of the collagen matrix by EDTA and reduced when NaOCl was used. Saturation of the collagen matrix by EDTA and EtOH changed the surface free energy of the dentin. In addition, the use of NaOCl negatively interfered with the properties evaluated. The increase of surface free energy and wettability of the dentin surface would allow higher penetration of the the adhesive system, which would be of importance to the clinical success of resin-dentin union.

  5. Modeling surface energy fluxes from a patchwork of fields with different soils and crops

    Science.gov (United States)

    Klein, Christian; Thieme, Christoph; Heinlein, Florian; Priesack, Eckart

    2017-04-01

    Agroecosystems are a dominant terrestrial land-use on planet earth and cover about 36% of the ice-free surface (12% pasture, 26% agriculture) [Foley2011]. Within this land use type, management practices vary strongly due to climate, cultural preferences, degree of industrialization, soil properties, crop rotations, field sizes, degree of land use sustainability, water availability, sowing and harvest dates, tillage, etc. These management practices influence abiotic environmental factors like water flow and heat transport within the ecosystem leading to changes of land surface fluxes. The relevance of vegetation (e.g. crops), ground cover, and soil properties to the moisture and energy exchanges between the land surface and the atmosphere is well known [McPherson 2007], but the impact of vegetation growth dynamics on energy fluxes is only partly understood [Gayler et al. 2014]. Thus, the structure of turbulence and the albedo evolve during the cropping period and large variations of heat can be measured on the field scale [Aubinet2012]. One issue of local distributed mixture of different land use is the measurement process which makes it challenging to evaluate simulations. Unfortunately, for meteorological flux-measurements like the Flux-Gradient or the Eddy Covariance (EC) method, comparability with simulations only exists in the ideal case, where fields have to be completely uniform in land use and flat within the reach of the footprint. Then a model with one specific land use would have the same underlying source area as the measurement. An elegant method to avoid the shortcoming of grid cell resolution is the so called mixed approach, which was recently implemented into the ecosystem model framework Expert-N [Biernath et al. 2013]. The aim of this study was to analyze the impact of the characteristics of five managed field plots, planted with winter wheat, potato and maize on the near surface soil moistures and on the near surface energy flux exchanges of the

  6. Advancements in Modelling of Land Surface Energy Fluxes with Remote Sensing at Different Spatial Scales

    DEFF Research Database (Denmark)

    Guzinski, Radoslaw

    uxes, such as sensible heat ux, ground heat ux and net radiation, are also necessary. While it is possible to measure those uxes with ground-based instruments at local scales, at region scales they usually need to be modelled or estimated with the help of satellite remote sensing data. Even though...... to increase the spatial resolution of the reliable DTD-modelled fluxes from 1 km to 30 m. Furthermore, synergies between remote sensing based models and distributed hydrological models were studied with the aim of improving spatial performance of the hydrological models through incorporation of remote sensing...... of this study was to look at, and improve, various approaches for modelling the land-surface energy uxes at different spatial scales. The work was done using physically-based Two-Source Energy Balance (TSEB) approach as well as semi-empirical \\Triangle" approach. The TSEB-based approach was the main focus...

  7. Surface modification of TC4 titanium alloy by high current pulsed electron beam (HCPEB) with different pulsed energy densities

    International Nuclear Information System (INIS)

    Gao, Yu-kui

    2013-01-01

    Highlights: •The hardness changes were determined by nanoindention method. •The surface integrity changes were investigated by different techniques. •The mechanism was analyzed based on AFM and TEM investigations. -- Abstract: Surface changes including surface topography and nanohardness distribution along surface layer were investigated for TC4 titanium alloy by different energy densities of high current pulsed electron beam (HCPEB). The surface topography was characterized by SEM and AFM, and cross-sectional TEM observation was performed to reveal the surface modification mechanism of TC4 titanium alloy by HCPEB. The surface roughness was modified by HCPEB and the polishing mechanism was analyzed by studying the cross section microstructure of electron beam treated specimens by SEM. The fine grain structure inherited from the rapid solidification of the melted layer as well as the strain hardening of the sub-surface are two of the factors responsible the increase in nanohardness

  8. Comparison of energy fluxes at the land surface-atmosphere interface in an Alpine valley as simulated with different models

    Directory of Open Access Journals (Sweden)

    G. Grossi

    2003-01-01

    Full Text Available Within the framework of a research project coupling meteorological and hydrological models in mountainous areas a distributed Snow-Soil-Vegetation-Atmosphere Transfer model was developed and applied to simulate the energy fluxes at the land surface – atmosphere interface in an Alpine valley (Toce Valley - North Italy during selected flood events in the last decade. Energy fluxes simulated by the distributed energy transfer model were compared with those simulated by a limited area meteorological model for the event of June 1997 and the differences in the spatial and temporal distribution. The Snow/Soil-Vegetation-Atmosphere Transfer model was also applied to simulate the energy fluxes at the land surface-atmosphere interface for a single cell, assumed to be representative of the Siberia site (Toce Valley, where a micro-meteorological station was installed and operated for 2.5 months in autumn 1999. The Siberia site is very close to the Nosere site, where a standard meteorological station was measuring precipitation, air temperature and humidity, global and net radiation and wind speed during the same special observing period. Data recorded by the standard meteorological station were used to force the energy transfer model and simulate the point energy fluxes at the Siberia site, while turbulent fluxes observed at the Siberia site were used to derive the latent heat flux from the energy balance equation. Finally, the hourly evapotranspiration flux computed by this procedure was compared to the evapotranspiration flux simulated by the energy transfer model. Keywords: energy exchange processes, land surface-atmosphere interactions, turbulent fluxes

  9. Damage of niobium surfaces caused by bombardment with 4He+ ions of different energies typical for T-20

    International Nuclear Information System (INIS)

    Guseva, M.I.; Gusev, V.; Martynenko, Yu.V.; Das, S.K.; Kaminsky, N.

    1979-01-01

    The surface damage of cold worked and annealed polycrystalline Nb irradiated at room temperature with He + ions sequentially at different energies over the range from 0.5 keV to 1.8 MeV has been investigated. The individual energy and the dose of the He + ion was chosen to match the theoretically calculated He + ion spectrum expected in the Tokamak T-20. In one set of irradiations, targets were irradiated at Kurchatov Institute starting with 0.5 keV 4 He + ions and extending up to 90 keV in eleven steps. Subsequently, the same area was irradiated at ANL starting at 150 keV and increased in eight steps up to 1.8 MeV. The irradiations were carried out for a total dose of 5.0 C/cm 2 . In another set of irradiations the sequence was reversed. Scanning electron microscopy results show formation of blisters and exfoliation. For the same dose the broad energy implant (due to sequential irradiation) appears to decrease the blister diameter and density as compared to irradiation with monoenergetic He + ions at a given energy (in the energy range considered). Some estimates of surface erosion yields due to blistering are given

  10. [Energy dispersive spectrum analysis of surface compositions of selective laser melting cobalt-chromium alloy fabricated by different processing parameters].

    Science.gov (United States)

    Qian, Liang; Zeng, Li; Wei, Bin; Gong, Yao

    2015-06-01

    To fabricate selective laser melting cobalt-chromium alloy samples by different processing parameters, and to analyze the changes of energy dispersive spectrum(EDS) on their surface. Nine groups were set up by orthogonal experimental design according to different laser powers,scanning speeds and powder feeding rates(laser power:2500-3000 W, scanning speed: 5-15 mm/s, powder feeding rate: 3-6 r/min). Three cylinder specimens(10 mm in diameter and 3 mm in thickness) were fabricated in each group through Rofin DL 035Q laser cladding system using cobalt-chromium alloy powders which were developed independently by our group.Their surface compositions were then measured by EDS analysis. Results of EDS analysis of the 9 groups fabricated by different processing parameters(Co:62.98%-67.13%,Cr:25.56%-28.50%,Si:0.49%-1.23%) were obtained. They were similar to the compositions of cobalt-chromium alloy used in dental practice. According to EDS results, the surface compositions of the selective laser melting cobalt-chromium alloy samples are stable and controllable, which help us gain a preliminary sight into the range of SLM processing parameters. Supported by "973" Program (2012CB910401) and Research Fund of Science and Technology Committee of Shanghai Municipality (12441903001 and 13140902701).

  11. Comparison and uncertainty evaluation of different calibration protocols and ionization chambers for low-energy surface brachytherapy dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Candela-Juan, C., E-mail: ccanjuan@gmail.com [Radiation Oncology Department, La Fe University and Polytechnic Hospital, Valencia 46026 (Spain); Vijande, J. [Department of Atomic, Molecular, and Nuclear Physics, University of Valencia, Burjassot 46100, Spain and Instituto de Física Corpuscular (UV-CSIC), Paterna 46980 (Spain); García-Martínez, T. [Radiation Oncology Department, Hospital La Ribera, Alzira 46600 (Spain); Niatsetski, Y.; Nauta, G.; Schuurman, J. [Elekta Brachytherapy, Veenendaal 3905 TH (Netherlands); Ouhib, Z. [Radiation Oncology Department, Lynn Regional Cancer Center, Boca Raton Community Hospital, Boca Raton, Florida 33486 (United States); Ballester, F. [Department of Atomic, Molecular, and Nuclear Physics, University of Valencia, Burjassot 46100 (Spain); Perez-Calatayud, J. [Radiation Oncology Department, La Fe University and Polytechnic Hospital, Valencia 46026, Spain and Department of Radiotherapy, Clínica Benidorm, Benidorm 03501 (Spain)

    2015-08-15

    Purpose: A surface electronic brachytherapy (EBT) device is in fact an x-ray source collimated with specific applicators. Low-energy (<100 kVp) x-ray beam dosimetry faces several challenges that need to be addressed. A number of calibration protocols have been published for x-ray beam dosimetry. The media in which measurements are performed are the fundamental difference between them. The aim of this study was to evaluate the surface dose rate of a low-energy x-ray source with small field applicators using different calibration standards and different small-volume ionization chambers, comparing the values and uncertainties of each methodology. Methods: The surface dose rate of the EBT unit Esteya (Elekta Brachytherapy, The Netherlands), a 69.5 kVp x-ray source with applicators of 10, 15, 20, 25, and 30 mm diameter, was evaluated using the AAPM TG-61 (based on air kerma) and International Atomic Energy Agency (IAEA) TRS-398 (based on absorbed dose to water) dosimetry protocols for low-energy photon beams. A plane parallel T34013 ionization chamber (PTW Freiburg, Germany) calibrated in terms of both absorbed dose to water and air kerma was used to compare the two dosimetry protocols. Another PTW chamber of the same model was used to evaluate the reproducibility between these chambers. Measurements were also performed with two different Exradin A20 (Standard Imaging, Inc., Middleton, WI) chambers calibrated in terms of air kerma. Results: Differences between surface dose rates measured in air and in water using the T34013 chamber range from 1.6% to 3.3%. No field size dependence has been observed. Differences are below 3.7% when measurements with the A20 and the T34013 chambers calibrated in air are compared. Estimated uncertainty (with coverage factor k = 1) for the T34013 chamber calibrated in water is 2.2%–2.4%, whereas it increases to 2.5% and 2.7% for the A20 and T34013 chambers calibrated in air, respectively. The output factors, measured with the PTW chambers

  12. Using machine learning and surface reconstruction to accurately differentiate different trajectories of mood and energy dysregulation in youth.

    Science.gov (United States)

    Versace, Amelia; Sharma, Vinod; Bertocci, Michele A; Bebko, Genna; Iyengar, Satish; Dwojak, Amanda; Bonar, Lisa; Perlman, Susan B; Schirda, Claudiu; Travis, Michael; Gill, Mary Kay; Diwadkar, Vaibhav A; Sunshine, Jeffrey L; Holland, Scott K; Kowatch, Robert A; Birmaher, Boris; Axelson, David; Frazier, Thomas W; Arnold, L Eugene; Fristad, Mary A; Youngstrom, Eric A; Horwitz, Sarah M; Findling, Robert L; Phillips, Mary L

    2017-01-01

    Difficulty regulating positive mood and energy is a feature that cuts across different pediatric psychiatric disorders. Yet, little is known regarding the neural mechanisms underlying different developmental trajectories of positive mood and energy regulation in youth. Recent studies indicate that machine learning techniques can help elucidate the role of neuroimaging measures in classifying individual subjects by specific symptom trajectory. Cortical thickness measures were extracted in sixty-eight anatomical regions covering the entire brain in 115 participants from the Longitudinal Assessment of Manic Symptoms (LAMS) study and 31 healthy comparison youth (12.5 y/o;-Male/Female = 15/16;-IQ = 104;-Right/Left handedness = 24/5). Using a combination of trajectories analyses, surface reconstruction, and machine learning techniques, the present study aims to identify the extent to which measures of cortical thickness can accurately distinguish youth with higher (n = 18) from those with lower (n = 34) trajectories of manic-like behaviors in a large sample of LAMS youth (n = 115; 13.6 y/o; M/F = 68/47, IQ = 100.1, R/L = 108/7). Machine learning analyses revealed that widespread cortical thickening in portions of the left dorsolateral prefrontal cortex, right inferior and middle temporal gyrus, bilateral precuneus, and bilateral paracentral gyri and cortical thinning in portions of the right dorsolateral prefrontal cortex, left ventrolateral prefrontal cortex, and right parahippocampal gyrus accurately differentiate (Area Under Curve = 0.89;p = 0.03) youth with different (higher vs lower) trajectories of positive mood and energy dysregulation over a period up to 5years, as measured by the Parent General Behavior Inventory-10 Item Mania Scale. Our findings suggest that specific patterns of cortical thickness may reflect transdiagnostic neural mechanisms associated with different temporal trajectories of positive mood and energy dysregulation in youth. This approach has

  13. Using machine learning and surface reconstruction to accurately differentiate different trajectories of mood and energy dysregulation in youth.

    Directory of Open Access Journals (Sweden)

    Amelia Versace

    Full Text Available Difficulty regulating positive mood and energy is a feature that cuts across different pediatric psychiatric disorders. Yet, little is known regarding the neural mechanisms underlying different developmental trajectories of positive mood and energy regulation in youth. Recent studies indicate that machine learning techniques can help elucidate the role of neuroimaging measures in classifying individual subjects by specific symptom trajectory. Cortical thickness measures were extracted in sixty-eight anatomical regions covering the entire brain in 115 participants from the Longitudinal Assessment of Manic Symptoms (LAMS study and 31 healthy comparison youth (12.5 y/o;-Male/Female = 15/16;-IQ = 104;-Right/Left handedness = 24/5. Using a combination of trajectories analyses, surface reconstruction, and machine learning techniques, the present study aims to identify the extent to which measures of cortical thickness can accurately distinguish youth with higher (n = 18 from those with lower (n = 34 trajectories of manic-like behaviors in a large sample of LAMS youth (n = 115; 13.6 y/o; M/F = 68/47, IQ = 100.1, R/L = 108/7. Machine learning analyses revealed that widespread cortical thickening in portions of the left dorsolateral prefrontal cortex, right inferior and middle temporal gyrus, bilateral precuneus, and bilateral paracentral gyri and cortical thinning in portions of the right dorsolateral prefrontal cortex, left ventrolateral prefrontal cortex, and right parahippocampal gyrus accurately differentiate (Area Under Curve = 0.89;p = 0.03 youth with different (higher vs lower trajectories of positive mood and energy dysregulation over a period up to 5years, as measured by the Parent General Behavior Inventory-10 Item Mania Scale. Our findings suggest that specific patterns of cortical thickness may reflect transdiagnostic neural mechanisms associated with different temporal trajectories of positive mood and energy dysregulation in youth. This

  14. Water models based on a single potential energy surface and different molecular degrees of freedom

    Science.gov (United States)

    Saint-Martin, Humberto; Hernández-Cobos, Jorge; Ortega-Blake, Iván

    2005-06-01

    Up to now it has not been possible to neatly assess whether a deficient performance of a model is due to poor parametrization of the force field or the lack of inclusion of enough molecular properties. This work compares several molecular models in the framework of the same force field, which was designed to include many-body nonadditive effects: (a) a polarizable and flexible molecule with constraints that account for the quantal nature of the vibration [B. Hess, H. Saint-Martin, and H. J. C. Berendsen, J. Chem. Phys. 116, 9602 (2002), H. Saint-Martin, B. Hess, and H. J. C. Berendsen, J. Chem. Phys. 120, 11133 (2004)], (b) a polarizable and classically flexible molecule [H. Saint-Martin, J. Hernández-Cobos, M. I. Bernal-Uruchurtu, I. Ortega-Blake, and H. J. C. Berendsen, J. Chem. Phys. 113, 10899 (2000)], (c) a polarizable and rigid molecule, and finally (d) a nonpolarizable and rigid molecule. The goal is to determine how significant the different molecular properties are. The results indicate that all factors—nonadditivity, polarizability, and intramolecular flexibility—are important. Still, approximations can be made in order to diminish the computational cost of the simulations with a small decrease in the accuracy of the predictions, provided that those approximations are counterbalanced by the proper inclusion of an effective molecular property, that is, an average molecular geometry or an average dipole. Hence instead of building an effective force field by parametrizing it in order to reproduce the properties of a specific phase, a building approach is proposed that is based on adequately restricting the molecular flexibility and/or polarizability of a model potential fitted to unimolecular properties, pair interactions, and many-body nonadditive contributions. In this manner, the same parental model can be used to simulate the same substance under a wide range of thermodynamic conditions. An additional advantage of this approach is that, as the force

  15. Uncertainties in surface mass and energy flux estimates due to different eddy covariance sensors and technical set-up

    Science.gov (United States)

    Arriga, Nicola; Fratini, Gerardo; Forgione, Antonio; Tomassucci, Michele; Papale, Dario

    2010-05-01

    Eddy covariance is a well established and widely used methodology for the measurement of turbulent fluxes of mass and energy in the atmospheric boundary layer, in particular to estimate CO2/H2O and heat exchange above ecologically relevant surfaces (Aubinet 2000, Baldocchi 2003). Despite its long term application and theoretical studies, many issues are still open about the effect of different experimental set-up on final flux estimates. Open issues are the evaluation of the performances of different kind of sensors (e.g. open path vs closed path infra-red gas analysers, vertical vs horizontal mounting ultrasonic anemometers), the quantification of the impact of corresponding physical corrections to be applied to get robust flux estimates taking in account all processes concurring to the measurement (e.g. the so-called WPL term, signal attenuation due to air sampling system for closed path analyser, relative position of analyser and anemometer) and the differences between several data transmission protocols used (analogue, digital RS-232, SDM). A field experiment was designed to study these issues using several instruments among those most used within the Fluxnet community and to compare their performances under conditions supposed to be critical: rainy and cold weather conditions for open-path analysers (Burba 2008), water transport and absorption at high air relative humidity conditions for closed-path systems (Ibrom, 2007), frequency sampling limits and recorded data robustness due to different transmission protocols (RS232, SDM, USB, Ethernet) and finally the effect of the displacement between anemometer and analyser using at least two identical analysers placed at different horizontal and vertical distances from the anemometer. Aim of this experiment is to quantify the effect of several technical solutions on the final estimates of fluxes measured at a point in the space and if they represent a significant source of uncertainty for mass and energy cycle

  16. Surface energy anisotropy of tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, R; Grenga, H E [Georgia Inst. of Tech., Atlanta (USA). School of Chemical Engineering

    1976-10-01

    Field-ion microscopy was used to study the faceting behavior and/or surface energy anisotropy of tungsten in vacuum and in hydrogen. In vacuum below 1700 K the activation energy for (110) facet growth agreed with values previously reported for surface diffusion on tungsten. The observed anisotropy values at 0.5 Tsub(m), where Tsub(m) is the absolute melting temperature of tungsten (approximately 3680 K), were different from those previously reported at higher temperatures and more nearly agreed with broken bond calculations based on Mie potential using m=5, n=8, and a 1.5% lattice expansion. Hydrogen appeared to have a negligible effect on surface energy anisotropy, but did preferentially increase surface diffusion rates on (310) regions.

  17. Energy harvesting through gas dynamics in the free molecular flow regime between structured surfaces at different temperatures

    DEFF Research Database (Denmark)

    Baier, Tobias; Dölger, Julia; Hardt, Steffen

    2014-01-01

    For a gas confined between surfaces held at different temperatures the velocity distribution shows a significant deviation from the Maxwell distribution when the mean free path of the molecules is comparable to or larger than the channel dimensions. If one of the surfaces is suitably structured...... from the thermal creep flow that has gained more attention so far. This situation is studied in the limit of free-molecular flow for the case that an unstructured surface is allowed to move tangentially with respect to a structured surface. Parameter studies are conducted, and configurations...

  18. Energy harvesting through gas dynamics in the free molecular flow regime between structured surfaces at different temperatures

    Science.gov (United States)

    Baier, Tobias; Dölger, Julia; Hardt, Steffen

    2014-05-01

    For a gas confined between surfaces held at different temperatures the velocity distribution shows a significant deviation from the Maxwell distribution when the mean free path of the molecules is comparable to or larger than the channel dimensions. If one of the surfaces is suitably structured, this nonequilibrium distribution can be exploited for momentum transfer in a tangential direction between the two surfaces. This opens up the possibility to extract work from the system which operates as a heat engine. Since both surfaces are held at constant temperatures, the mode of momentum transfer is different from the thermal creep flow that has gained more attention so far. This situation is studied in the limit of free-molecular flow for the case that an unstructured surface is allowed to move tangentially with respect to a structured surface. Parameter studies are conducted, and configurations with maximum thermodynamic efficiency are identified. Overall, it is shown that significant efficiencies can be obtained by tangential momentum transfer between structured surfaces.

  19. Surface energy of explosive nanoparticles

    Science.gov (United States)

    Pineau, Nicolas; Bidault, Xavier; Soulard, Laurent

    2017-06-01

    Recent experimental studies show that nanostructuration has a substantial impact on the detonation of high explosives: a nanostructured one leads to smaller nanodiamonds than a microstructured one. Whether it comes from a higher surface energy or from porosity, the origin of these different behaviors must be investigated. The surface energy of TATB nanoparticles with a radius from 2 nm upto 60 nm has been determined by means of ReaxFF-based simulations. Then, using the Rankine-Hugoniot relations and the equation of states of the bulk material, the contribution of this excess energy to the heating of a shock-compressed nanostructured (and porous) material is evaluated and compared to the thermal effect due to its porosity collapse. A maximum temperature increase of 50 K is found for 4-nm nanoparticles, which remains negligible when compared to the few hundred degrees induced by the compaction work.

  20. On Energy Inequality for the Problem on the Evolution of Two Fluids of Different Types Without Surface Tension

    Science.gov (United States)

    Denisova, Irina Vlad.

    2015-03-01

    The paper deals with the motion of two immiscible viscous fluids in a container, one of the fluids being compressible while another one being incompressible. The interface between the fluids is an unknown closed surface where surface tension is neglected. We assume the compressible fluid to be barotropic, the pressure being given by an arbitrary smooth increasing function. This problem is considered in anisotropic Sobolev-Slobodetskiǐ spaces. We show that the L 2-norms of the velocity and deviation of compressible fluid density from the mean value decay exponentially with respect to time. The proof is based on a local existence theorem (Denisova, Interfaces Free Bound 2:283-312, 2000) and on the idea of constructing a function of generalized energy, proposed by Padula (J Math Fluid Mech 1:62-77, 1999). In addition, we eliminate the restrictions for the viscosities which appeared in Denisova (Interfaces Free Bound 2:283-312, 2000).

  1. Damage of niobium surfaces caused by bombardment with 4He+ ions of different energies typical for T-20

    International Nuclear Information System (INIS)

    Guseva, M.I.; Gusev, V.; Martynenko, Yu.V.; Das, S.K.; Kaminsky, M.

    1979-01-01

    The aim of the present studies was to study surface damage due to blistering of both annealed and cold-worked niobium (a candidate first wall material for keV) irradiated sequentially with 4 He + ions with energies of 0.5 to 1800 keV for a total dose of 5.0 C/cm 2 . A typical surface of cold-worked Nb after irradiations with 4 He + ions with increasing energy from 0.5 to 90 keV is shown. The blister diameters range from 0.1 μm to 3 μm, and most of the blisters have exfoliated. The blisters fall into several size classes, the two most dominant ones having most probable blister diameters of approx. 0.27 μm and approx. 2.0 μm. The skin thickness of the larger blisters was measured to be approx. 0.23 μm. Also shown is the same area after irradiation with 150-1800-keV 4 He + irradiation for a dose of 0.66 C/cm 2 . A few additional blisters can be seen. A cold-worked Nb surface that was irradiated only with 150-1800-keV 4 He + ions is also shown. It is seen that prior irradiation with 0.5-90-keV 4 He + helped in significantly reducing blistering. For a total dose of 0.5 C/cm 2 , the erosion yield due to helium blistering of Nb ranges from (5.4 +- 2.0) x 10 -3 to (1.5 +- 0.7) x 10 -2 atoms/ion. For the cold-worked Nb target the results indicate clearly that the 4 He + implantations for the energy range from 0.5 to 90 keV help to reduce both the density and diameter of blisters formed by subsequent He-implantation for the energy ranging from 150 to 1800 keV. 2 figures

  2. Concavity Theorems for Energy Surfaces

    OpenAIRE

    Giraud, B. G.; Karataglidis, S.

    2011-01-01

    Concavity properties prevent the existence of significant landscapes in energy surfaces obtained by strict constrained energy minimizations. The inherent contradiction is due to fluctuations of collective coordinates. A solution to those fluctuations is given.

  3. Surface Meteorology and Solar Energy

    Data.gov (United States)

    National Aeronautics and Space Administration — Surface Meteorology and Solar Energy data - over 200 satellite-derived meteorology and solar energy parameters, monthly averaged from 22 years of data, global solar...

  4. The surface energy of metals

    DEFF Research Database (Denmark)

    Vitos, Levente; Ruban, Andrei; Skriver, Hans Lomholt

    1998-01-01

    We have used density functional theory to establish a database of surface energies for low index surfaces of 60 metals in the periodic table. The data may be used as a consistent starting point for models of surface science phenomena. The accuracy of the database is established in a comparison...

  5. Surface hardness evaluation of different composite resin materials: influence of sports and energy drinks immersion after a short-term period

    Directory of Open Access Journals (Sweden)

    Ugur Erdemir

    2013-04-01

    Full Text Available Objectives: This study evaluated the effect of sports and energy drinks on the surface hardness of different composite resin restorative materials over a 1-month period. Material and Methods: A total of 168 specimens: Compoglass F, Filtek Z250, Filtek Supreme, and Premise were prepared using a customized cylindrical metal mould and they were divided into six groups (N=42; n=7 per group. For the control groups, the specimens were stored in distilled water for 24 hours at 37°C and the water was renewed daily. For the experimental groups, the specimens were immersed in 5 mL of one of the following test solutions: Powerade, Gatorade, X-IR, Burn, and Red Bull, for two minutes daily for up to a 1-month test period and all the solutions were refreshed daily. Surface hardness was measured using a Vickers hardness measuring instrument at baseline, after 1-week and 1-month. Data were statistically analyzed using Multivariate repeated measure ANOVA and Bonferroni's multiple comparison tests (α=0.05. Results: Multivariate repeated measures ANOVA revealed that there were statistically significant differences in the hardness of the restorative materials in different immersion times (p<0.001 in different solutions (p<0.001. The effect of different solutions on the surface hardness values of the restorative materials was tested using Bonferroni's multiple comparison tests, and it was observed that specimens stored in distilled water demonstrated statistically significant lower mean surface hardness reductions when compared to the specimens immersed in sports and energy drinks after a 1-month evaluation period (p<0.001. The compomer was the most affected by an acidic environment, whereas the composite resin materials were the least affected materials. Conclusions: The effect of sports and energy drinks on the surface hardness of a restorative material depends on the duration of exposure time, and the composition of the material.

  6. [Influence of different surface treatments on porcelain surface topography].

    Science.gov (United States)

    Tai, Yinxia; Zhu, Xianchun; Sen, Yan; Liu, Chang; Zhang, Xian; Shi, Xueming

    2013-02-01

    To evaluate the influence of different surface treatments on porcelain surface topography. Metal ceramic prostheses in 6 groups were treated according to the different surface treatment methods, and the surface topography was observed through scanning electron microscope (SEM). Group A was the control one (untreated), group B was etched by 9.6% hydrofluoric acid(HF), group C was deglazed by grinding and then etched by 9.6% HF, group D was treated with Nd: YAG laser irradiation(0.75 W) and HF etching, group E was treated with Nd: YAG laser irradiation (1.05 W) and HF etching, and group F was treated with laser irradiation (1.45 W) and HF etching. Surface topography was different in different groups. A lot of inerratic cracks with the shapes of rhombuses and grid, and crater with a shape of circle were observed on the ceramic surface after treatment with energy parameters of 1.05 W Nd: YAG laser irradiation and 9.6% HF etching (group E). Surface topography showed a lot of concaves on the inner wall of the cracks, and the concaves with diameter of 1-5 microm could be observed on the inner wall of the holes, which had a diameter of 20 microm under SEM. The use of Nd: YAG laser irradiation with the energy parameters of 1.05 W and the HF with a concentration of 9.6% can evenly coarsen the porcelain surface, that is an effective surface treatment method.

  7. Symmetry energy in nuclear surface

    International Nuclear Information System (INIS)

    Danielewicz, P.; Lee, Jenny

    2009-01-01

    Interplay between the dependence of symmetry energy on density and the variation of nucleonic densities across nuclear surface is discussed. That interplay gives rise to the mass dependence of the symmetry coefficient in an energy formula. Charge symmetry of the nuclear interactions allows to introduce isoscalar and isovector densities that are approximately independent of the magnitude of neutron-proton asymmetry. (author)

  8. Solar energy converter using surface plasma waves

    Science.gov (United States)

    Anderson, L. M. (Inventor)

    1984-01-01

    Sunlight is dispersed over a diffraction grating formed on the surface of a conducting film on a substrate. The angular dispersion controls the effective grating period so that a matching spectrum of surface plasmons is excited for parallel processing on the conducting film. The resulting surface plasmons carry energy to an array of inelastic tunnel diodes. This solar energy converter does not require different materials for each frequency band, and sunlight is directly converted to electricity in an efficient manner by extracting more energy from the more energetic photons.

  9. Surface energy of metal alloy nanoparticles

    Science.gov (United States)

    Takrori, Fahed M.; Ayyad, Ahmed

    2017-04-01

    The measurement of surface energy of alloy nanoparticles experimentally is still a challenge therefore theoretical work is necessary to estimate its value. In continuation of our previous work on the calculation of the surface energy of pure metallic nanoparticles we have extended our work to calculate the surface energy of different alloy systems, namely, Co-Ni, Au-Cu, Cu-Al, Cu-Mg and Mo-Cs binary alloys. It is shown that the surface energy of metallic binary alloy decreases with decreasing particle size approaching relatively small values at small sizes. When both metals in the alloy obey the Hume-Rothery rules, the difference in the surface energy is small at the macroscopic as well as in the nano-scale. However when the alloy deviated from these rules the difference in surface energy is large in the macroscopic and in the nano scales. Interestingly when solid solution formation is not possible at the macroscopic scale according to the Hume-Rothery rules, it is shown it may form at the nano-scale. To our knowledge these findings here are presented for the first time and is challenging from fundamental as well as technological point of views.

  10. Surface meteorology and Solar Energy

    Science.gov (United States)

    Stackhouse, Paul W. (Principal Investigator)

    The Release 5.1 Surface meteorology and Solar Energy (SSE) data contains parameters formulated for assessing and designing renewable energy systems. Parameters fall under 11 categories including: Solar cooking, solar thermal applications, solar geometry, tilted solar panels, energy storage systems, surplus product storage systems, cloud information, temperature, wind, other meteorological factors, and supporting information. This latest release contains new parameters based on recommendations by the renewable energy industry and it is more accurate than previous releases. On-line plotting capabilities allow quick evaluation of potential renewable energy projects for any region of the world. The SSE data set is formulated from NASA satellite- and reanalysis-derived insolation and meteorological data for the 10-year period July 1983 through June 1993. Results are provided for 1 degree latitude by 1 degree longitude grid cells over the globe. Average daily and monthly measurements for 1195 World Radiation Data Centre ground sites are also available. [Mission Objectives] The SSE project contains insolation and meteorology data intended to aid in the development of renewable energy systems. Collaboration between SSE and technology industries such as the Hybrid Optimization Model for Electric Renewables ( HOMER ) may aid in designing electric power systems that employ some combination of wind turbines, photovoltaic panels, or diesel generators to produce electricity. [Temporal_Coverage: Start_Date=1983-07-01; Stop_Date=1993-06-30] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180].

  11. Energy conservation potential of surface modification technologies

    Energy Technology Data Exchange (ETDEWEB)

    Le, H.K.; Horne, D.M.; Silberglitt, R.S.

    1985-09-01

    This report assesses the energy conservation impact of surface modification technologies on the metalworking industries. The energy conservation impact of surface modification technologies on the metalworking industries is assessed by estimating their friction and wear tribological sinks and the subsequent reduction in these sinks when surface modified tools are used. Ion implantation, coatings, and laser and electron beam surface modifications are considered.

  12. Statistical studies on the light output and energy resolution of small LSO single crystals with different surface treatments combined with various reflector materials

    CERN Document Server

    Heinrichs, U; Bussmann, N; Engels, R; Kemmerling, G; Weber, S; Ziemons, K

    2002-01-01

    The optimization of light output and energy resolution of scintillators is of special interest for the development of high resolution and high sensitivity PET. The aim of this work is to obtain statistically reliable results concerning optimal surface treatment of scintillation crystals and the selection of reflector material. For this purpose, raw, mechanically polished and etched LSO crystals (size 2x2x10 mm sup 3) were combined with various reflector materials (Teflon tape, Teflon matrix, BaSO sub 4) and exposed to a sup 2 sup 2 Na source. In order to ensure the statistical reliability of the results, groups of 10 LSO crystals each were measured for all combinations of surface treatment and reflector material. Using no reflector material the light output increased up to 551+-35% by mechanical polishing the surface compared to 100+-5% for raw crystals. Etching the surface increased the light output to 441+-29%. The untreated crystals had an energy resolution of 24.6+-4.0%. By mechanical polishing the surfac...

  13. Modification of Surface Energy via Direct Laser Ablative Surface Patterning

    Science.gov (United States)

    Wohl, Christopher J., Jr. (Inventor); Belcher, Marcus A. (Inventor); Connell, John W. (Inventor); Hopkins, John W. (Inventor)

    2015-01-01

    Surface energy of a substrate is changed without the need for any template, mask, or additional coating medium applied to the substrate. At least one beam of energy directly ablates a substrate surface to form a predefined topographical pattern at the surface. Each beam of energy has a width of approximately 25 micrometers and an energy of approximately 1-500 microJoules. Features in the topographical pattern have a width of approximately 1-500 micrometers and a height of approximately 1.4-100 micrometers.

  14. Surface Energy and Setting Process of Contacting Surfaces

    Directory of Open Access Journals (Sweden)

    M. V. Musokhranov

    2014-01-01

    Full Text Available The paper deals with a challenge in terms of ensuring an accuracy of the relative position of the conjugated surfaces that is to determine a coefficient of friction. To solve it, there is a proposal to use the surface energy, as a tool that influences the contacting parts nature. Presently, energy of the surface layers at best is only stated, but not used in practice.Analysis of the conditions of interaction between two contacting surfaces, such as seizing and setting cannot be explained only from the position of the roughness parameters. It is found that these phenomena are explained by the appearing gripe (setting bridges, which result from the energy of interaction between two or more adjacent surfaces. The emerging phenomenon such as micro welding, i.e. occurring bonds, is caused by the overflow of energy, according to the theory of physics, from the surface with a high level of energy to the surface with the smaller one to balance the system as a whole.The paper shows that through the use of process, controlling the depth of the surface layer and creating a certain structure, the energy level of the material as a whole can be specified. And this will allow us to provide the necessary performance and mechanical properties. It means to create as many gripe bridges as possible to ensure continuous positioning i.e. a fixed connection of the contacting surfaces.It was determined that to increase a value of the friction coefficient, the physical and mechanical properties of the surface layer of the parts material must be taken into account, namely, in the part body accumulate the energy to be consumed for forming the surface.The paper gives recommendations for including the parts of the surface energy in the qualitative indicators of characteristics. This will make a technologist, when routing a process, to choose such operations and modes to provide the designer-specified parameters not only of the accuracy and surface finish, but also of the

  15. Multilayer Relaxation and Surface Energies of Metallic Surfaces

    Science.gov (United States)

    Bozzolo, Guillermo; Rodriguez, Agustin M.; Ferrante, John

    1994-01-01

    The perpendicular and parallel multilayer relaxations of fcc (210) surfaces are studied using equivalent crystal theory (ECT). A comparison with experimental and theoretical results is made for AI(210). The effect of uncertainties in the input parameters on the magnitudes and ordering of surface relaxations for this semiempirical method is estimated. A new measure of surface roughness is proposed. Predictions for the multilayer relaxations and surface energies of the (210) face of Cu and Ni are also included.

  16. Surface free energy of alkali and transition metal nanoparticles

    International Nuclear Information System (INIS)

    Aqra, Fathi; Ayyad, Ahmed

    2014-01-01

    Graphical abstract: Size dependent surface free energy of spherical, cubic and disk Au nanoparticles. - Highlights: • A model to account for the surface free energy of metallic nanoparticles is described. • The model requires only the cohesive energy of the nanoparticle. • The surface free energy of a number of metallic nanoparticles has been calculated, and the obtained values agree well with existing data. • Surface energy falls down very fast when the number of atoms is less than hundred. • The model is applicable to any metallic nanoparticle. - Abstract: This paper addresses an interesting issue on the surface free energy of metallic nanoparticles as compared to the bulk material. Starting from a previously reported equation, a theoretical model, that involves a specific term for calculating the cohesive energy of nanoparticle, is established in a view to describe the behavior of surface free energy of metallic nanoparticles (using different shapes of particle: sphere, cube and disc). The results indicate that the behavior of surface energy is very appropriate for spherical nanoparticle, and thus, it is the most realistic shape of a nanoparticle. The surface energy of copper, silver, gold, platinum, tungsten, molybdenum, tantalum, paladium and alkali metallic nanoparticles is only prominent in the nanoscale size, and it decreases with the decrease of nanoparticle size. Thus, the surface free energy plays a more important role in determining the properties of nanoparticles than in bulk materials. It differs from shape to another, and falls down as the number of atoms (nanoparticle size) decreases. In the case of spherical nanoparticles, the onset of the sharp decrease in surface energy is observed at about 110 atom. A decrease of 16% and 45% in surface energy is found by moving from bulk to 110 atom and from bulk to 5 atom, respectively. The predictions are consistent with the reported data

  17. Waves energy comes to surface

    International Nuclear Information System (INIS)

    Guezel, J.Ch.

    2006-01-01

    The wave- or thalasso-energy, potentially as promising as wind energy, have started to develop in Europe. Great Britain has already a good experience in this domain but France shows also ambitions in this beginning industry with several projects in progress. This article makes an overview of the existing tide-, current- and wave-powered generators: tide mills, underwater hydro-turbines, immersed linear generators, air-compression systems, buoy systems, etc. (J.S.)

  18. Analysis of energy flow during playground surface impacts.

    Science.gov (United States)

    Davidson, Peter L; Wilson, Suzanne J; Chalmers, David J; Wilson, Barry D; Eager, David; McIntosh, Andrew S

    2013-10-01

    The amount of energy dissipated away from or returned to a child falling onto a surface will influence fracture risk but is not considered in current standards for playground impact-attenuating surfaces. A two-mass rheological computer simulation was used to model energy flow within the wrist and surface during hand impact with playground surfaces, and the potential of this approach to provide insights into such impacts and predict injury risk examined. Acceleration data collected on-site from typical playground surfaces and previously obtained data from children performing an exercise involving freefalling with a fully extended arm provided input. The model identified differences in energy flow properties between playground surfaces and two potentially harmful surface characteristics: more energy was absorbed by (work done on) the wrist during both impact and rebound on rubber surfaces than on bark, and rubber surfaces started to rebound (return energy to the wrist) while the upper limb was still moving downward. Energy flow analysis thus provides information on playground surface characteristics and the impact process, and has the potential to identify fracture risks, inform the development of safer impact-attenuating surfaces, and contribute to development of new energy-based arm fracture injury criteria and tests for use in conjunction with current methods.

  19. A systematic first-principles study of surface energies, surface relaxation and Friedel oscillation of magnesium surfaces

    International Nuclear Information System (INIS)

    Tang, Jia-Jun; Yang, Xiao-Bao; Zhao, Yu-Jun; OuYang, LiuZhang; Zhu, Min

    2014-01-01

    We systematically study the surface energies and surface relaxations of various low-index and high-index Mg surfaces. It is found that low-index surfaces are not necessarily stable as Mg(1 0  1-bar  0) is the most unstable surface in the series of Mg(1 0  1-bar  n) (n = 0–9). A surface-energy predicting model based on the bond cutting is proposed to explain the relative surface stabilities. The local relaxations of the low-index surfaces could be explained by the Friedel oscillation. For the high-index surfaces, the combination of charge smoothing effect and dramatic charge depletion influences the relaxations, which show a big difference from the low-index ones. Our findings provide theoretical data for considerable insights into the surface energies of hexagonal close-packed metals. (paper)

  20. Surface energy for electroluminescent polymers and indium-tin-oxide

    International Nuclear Information System (INIS)

    Zhong Zhiyou; Yin Sheng; Liu Chen; Zhong Youxin; Zhang Wuxing; Shi Dufang; Wang Chang'an

    2003-01-01

    The contact angles on the thin films of poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and indium-tin-oxide (ITO) were measured by the sessile-drop technique. The surface energies of the films were calculated using the Owens-Wendt (OW) and van Oss-Chaudhury-Good (vOCG) approaches. The overall total surface energies of MEH-PPV and the as-received ITO were 30.75 and 30.07 mJ/m 2 , respectively. Both approaches yielded almost the same surface energies. The surface energies were mainly contributed from the dispersion interactions or Lifshitz-van der Waals (LW) interactions for both MEH-PPV and ITO. The changes in the contact angles and surface energies of the ITO films, due to different solvent cleaning processes and oxygen plasma treatments, were analyzed. Experimental results revealed that the total surface energy of the ITO films increased after various cleaning processes. In comparison with different solvents used in this study, we found that methanol is an effective solvent for ITO cleaning, as a higher surface energy was observed. ITO films treated with oxygen plasma showed the highest surface energy. This work demonstrated that contact angle measurement is a useful method to diagnose the cleaning effect on ITO films

  1. Sorption Energy Maps of Clay Mineral Surfaces

    International Nuclear Information System (INIS)

    Cygan, Randall T.; Kirkpatrick, R. James

    1999-01-01

    A molecular-level understanding of mineral-water interactions is critical for the evaluation and prediction of the sorption properties of clay minerals that may be used in various chemical and radioactive waste disposal methods. Molecular models of metal sorption incorporate empirical energy force fields, based on molecular orbital calculations and spectroscopic data, that account for Coulombic, van der Waals attractive, and short-range repulsive energies. The summation of the non-bonded energy terms at equally-spaced grid points surrounding a mineral substrate provides a three dimensional potential energy grid. The energy map can be used to determine the optimal sorption sites of metal ions on the exposed surfaces of the mineral. By using this approach, we have evaluated the crystallographic and compositional control of metal sorption on the surfaces of kaolinite and illite. Estimates of the relative sorption energy and most stable sorption sites are derived based on a rigid ion approximation

  2. Effect of surface energy on powder compactibility.

    Science.gov (United States)

    Fichtner, Frauke; Mahlin, Denny; Welch, Ken; Gaisford, Simon; Alderborn, Göran

    2008-12-01

    The influence of surface energy on the compactibility of lactose particles has been investigated. Three powders were prepared by spray drying lactose solutions without or with low proportions of the surfactant polysorbate 80. Various powder and tablet characterisation procedures were applied. The surface energy of the powders was characterized by Inverse Gas Chromatography and the compressibility of the powders was described by the relationship between tablet porosity and compression pressure. The compactibility of the powders was analyzed by studying the evolution of tablet tensile strength with increasing compaction pressure and porosity. All powders were amorphous and similar in particle size, shape, and surface area. The compressibility of the powders and the microstructure of the formed tablets were equal. However, the compactibility and dispersive surface energy was dependent of the composition of the powders. The decrease in tablet strength correlated to the decrease in powder surface energy at constant tablet porosities. This supports the idea that tablet strength is controlled by formation of intermolecular forces over the areas of contact between the particles and that the strength of these bonding forces is controlled by surface energy which, in turn, can be altered by the presence of surfactants.

  3. Surface free energy for systems with integrable boundary conditions

    International Nuclear Information System (INIS)

    Goehmann, Frank; Bortz, Michael; Frahm, Holger

    2005-01-01

    The surface free energy is the difference between the free energies for a system with open boundary conditions and the same system with periodic boundary conditions. We use the quantum transfer matrix formalism to express the surface free energy in the thermodynamic limit of systems with integrable boundary conditions as a matrix element of certain projection operators. Specializing to the XXZ spin-1/2 chain we introduce a novel 'finite temperature boundary operator' which characterizes the thermodynamical properties of surfaces related to integrable boundary conditions

  4. SURFACE ENERGY BALANCE OVER ORANGE ORCHARD USING SURFACE RENEWAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    Salvatore Barbagallo

    2009-12-01

    Full Text Available Reliable estimation of surface sensible and latent heat flux is the most important process to appraise energy and mass exchange among atmosphere and biosphere. In this study the surface energy fluxes were measured over an irrigated orange orchard during 2005-2008 monitoring periods using a Surface Renewal- Energy Balance approach. The experimental area is located in a representative orchard growing area of eastern Sicily (Italy. The performance of Surface Renewal (SR analysis for estimating sensible heat flux (H was analysed and evaluated in terms of correlation with H fluxes from the eddy covariance (EC method. Study revealed that the mean available energy (RN- G and latent heat flux (LE were of about 300 W m-2 and 237 W m-2, respectively, during dry periods and unstable-case atmospheric conditions. The estimated crop coefficient Kc values for the orchard crop averaged close to 0.80, which is considerably higher than previous FAO studies that found the value to be 0.65 for citrus with 70% of ground cover. The intercepted photosynthetically active radiation (LI PAR by the crop was measured and relationships between LAI and crop coefficient (Kc were established.

  5. Energy loss spectroscopy applied to surface studies

    International Nuclear Information System (INIS)

    Lecante, J.

    1975-01-01

    The analysis of energy losses suffered by slow electrons (5eV to 300eV) back-scattered by single crystal surfaces appears to be a powerful method for surfaces studies. The inelastic scattering of these slow electrons limits their escape depth to the surface region. After a review of the basic excitation processes due to the interaction between electrons and surfaces (phonons, plasmons and electronic transitions) a brief discussion is given about the instruments needed for this electrons spectroscopy. Finally some experimental results are listed and it is shown that the comparison of the results given by ELS with other surface sensitive methods such as UPS is very fruitful and new information can be obtained. The improvement of theoretical studies on surface excitations due to slow electrons will provide in the next future the possibility of analysing in a more quantitative way the results given by ELS [fr

  6. Adsorption energy of iron-phthalocyanine on crystal surfaces

    International Nuclear Information System (INIS)

    Struzzi, C.; Scardamaglia, M.; Angelucci, M; Massimi, L.; Mariani, C.; Betti, G.

    2013-01-01

    The adsorption energy of iron-phthalocyanine (FePc) deposited on different crystal surfaces is studied by thermal desorption spectroscopy. A thin film of molecules has been absorbed on highly oriented pyrolytic graphite (HOPG), on graphene epitaxially grown on Ir(111), and on Au(110). Activation energies for the desorption of a molecular thin film and for the FePc single layer are determined at the three surfaces. The desorption temperature measured for the thin films is only slightly dependent on the substrate, since it is mostly dominated by molecule-molecule interactions. A definitely different desorption temperature is found at the single-layer coverage: we find an increasing desorption temperature going from HOPG, to graphene/Ir, to the Au(110) surface. The different adsorption energies of the first FePc layer in contact with the substrate surface are discussed taking into account the interaction and the growth morphology.

  7. Surface Plasmon-Assisted Solar Energy Conversion.

    Science.gov (United States)

    Dodekatos, Georgios; Schünemann, Stefan; Tüysüz, Harun

    2016-01-01

    The utilization of localized surface plasmon resonance (LSPR) from plasmonic noble metals in combination with semiconductors promises great improvements for visible light-driven photocatalysis, in particular for energy conversion. This review summarizes the basic principles of plasmonic photocatalysis, giving a comprehensive overview about the proposed mechanisms for enhancing the performance of photocatalytically active semiconductors with plasmonic devices and their applications for surface plasmon-assisted solar energy conversion. The main focus is on gold and, to a lesser extent, silver nanoparticles in combination with titania as semiconductor and their usage as active plasmonic photocatalysts. Recent advances in water splitting, hydrogen generation with sacrificial organic compounds, and CO2 reduction to hydrocarbons for solar fuel production are highlighted. Finally, further improvements for plasmonic photocatalysts, regarding performance, stability, and economic feasibility, are discussed for surface plasmon-assisted solar energy conversion.

  8. Surface energy and crystallization phenomena of ammonium dinitramide

    Energy Technology Data Exchange (ETDEWEB)

    Teipel, Ulrich; Heintz, Thomas [Fraunhofer-Institut fuer Chemische Technologie (ICT), PO Box 1240, D-76318 Pfinztal (Germany)

    2005-12-01

    Ammonium dinitramide (ADN) was characterized during recrystallization from the melt. The surface tension of molten ADN at 97 C was measured to be 89 mN/m. The wetting angles between molten ADN and different solid surfaces (polytetrafluoroethylene, glass, steel, and aluminum) were determined. The wettability depends on the surface tension of molten ADN, the free surface energy of the solid surfaces and the interfacial tension between the solid and liquid. Observations of the recrystallization behavior of molten ADN showed that nucleation does not occur, even at super cooling rates of 70 K. Crystallization can be initiated by the application of seed crystals. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  9. Wettability and surface free energy of polarised ceramic biomaterials

    International Nuclear Information System (INIS)

    Nakamura, Miho; Hori, Naoko; Namba, Saki; Yamashita, Kimihiro; Toyama, Takeshi; Nishimiya, Nobuyuki

    2015-01-01

    The surface modification of ceramic biomaterials used for medical devices is expected to improve osteoconductivity through control of the interfaces between the materials and living tissues. Polarisation treatment induced surface charges on hydroxyapatite, β-tricalcium phosphate, carbonate-substituted hydroxyapatite and yttria-stabilized zirconia regardless of the differences in the carrier ions participating in the polarisation. Characterization of the surfaces revealed that the wettability of the polarised ceramic biomaterials was improved through the increase in the surface free energies compared with conventional ceramic surfaces. (note)

  10. Surface analysis of titanium dental implants with different topographies

    Directory of Open Access Journals (Sweden)

    Silva M.H. Prado da

    2000-01-01

    Full Text Available Cylindrical dental implants made of commercially pure titanium were analysed in four different surface finishes: as-machined, Al2O3 blasted with Al2O3 particles, plasma-sprayed with titanium beads and electrolytically coated with hydroxyapatite. Scanning electron microscopy (SEM with Energy Dispersive X-ray Analysis (EDX revealed the topography of the surfaces and provided qualitative results of the chemical composition of the different implants. X-ray Photoelectron Spectroscopy (XPS was used to perform chemical analysis on the surface of the implants while Laser Scanning Confocal Microscopy (LSM produced topographic maps of the analysed surfaces. Optical Profilometry was used to quantitatively characterise the level of roughness of the surfaces. The implant that was plasma-sprayed and the hydroxyapatite coated implant showed the roughest surface, followed by the implant blasted with alumina and the as-machined implant. Some remnant contamination from the processes of blasting, coating and cleaning was detected by XPS.

  11. Analysis of surface with low energy ions

    International Nuclear Information System (INIS)

    Oliver, A.; Miranda, J.

    1989-01-01

    Nuclear techniques applied to element analysis presents different characteristics depending on projectile energy. It can seen observed than an energy (E ≅ 1 MeV) exists which separate two regions for which sensitivity, information analysis and resolution in detection are different. For this work, we describe for the energy region E ≤ 1 MeV, the advantage of the three most used techniques which are PIXE, RBS y RNR. (Author)

  12. Energy loss in grazing proton-surface collisions

    Energy Technology Data Exchange (ETDEWEB)

    Juaristi, J I [Dept. Fisica de Materiales, Facultad de Quimicas, UPV/EHU, San Sebastian (Spain); Garcia de Abajo, F J [Dept. Ciencias de la Computacion e Inteligencia Artificial, Facultad de Informatica, UPV/EHU, San Sebastian (Spain)

    1994-05-01

    The energy loss of fast protons, with energy E > 100 keV, specularly reflected on a solid surface with glancing angle of incidence of the order of a mrad is analysed on theoretical grounds. Two different contributions can be distinguished: (i) energy losses originating from the interaction with the valence band, accounted for through an induced force, and (ii) the excitation of electron bound states of the target atoms. The results are compared with available experimental data. (orig.)

  13. Energy loss in grazing proton-surface collisions

    International Nuclear Information System (INIS)

    Juaristi, J.I.; Garcia de Abajo, F.J.

    1994-01-01

    The energy loss of fast protons, with energy E > 100 keV, specularly reflected on a solid surface with glancing angle of incidence of the order of a mrad is analysed on theoretical grounds. Two different contributions can be distinguished: i) energy losses originating from the interaction with the valence band, accounted for through an induced force, and ii) the excitation of electron bound states of the target atoms. The results are compared with available experimental data. (orig.)

  14. Energy loss spectroscopy applied to surface studies

    International Nuclear Information System (INIS)

    Lecante, J.

    1975-01-01

    The analysis of energy losses suffered by slow electrons (5 eV to 300 eV) back-scattered by single crystal surfaces appears to be a powerful method for surfaces studies. The inelastic scattering of these slow electrons limits their escape depth to the surface region which is defined here. After a review of the basic excitation processes due to the interaction between electrons and surfaces (phonons, plasmons and electronic transitions) a brief discussion is given about the instruments needed for this electron spectroscopy. Finally some experimental results are listed and it is shown that the comparison of the results given by ELS with other surface sensitive methods such as UPS is very fruitful and new information can be obtained [fr

  15. Calculation of the surface free energy of fcc copper nanoparticles

    International Nuclear Information System (INIS)

    Jia Ming; Lai Yanqing; Tian Zhongliang; Liu Yexiang

    2009-01-01

    Using molecular dynamics simulations with the modified analytic embedded-atom method we calculate the Gibbs free energy and surface free energy for fcc Cu bulk, and further obtain the Gibbs free energy of nanoparticles. Based on the Gibbs free energy of nanoparticles, we have investigated the heat capacity of copper nanoparticles. Calculation results indicate that the Gibbs free energy and the heat capacity of nanoparticles can be divided into two parts: bulk quantity and surface quantity. The molar heat capacity of the bulk sample is lower compared with the molar heat capacity of nanoparticles, and this difference increases with the decrease in the particle size. It is also observed that the size effect on the thermodynamic properties of Cu nanoparticles is not really significant until the particle is less than about 20 nm. It is the surface atoms that decide the size effect on the thermodynamic properties of nanoparticles

  16. Surface energy of very neutron rich nuclei

    CERN Document Server

    Von Groote, H

    1976-01-01

    For a microscopic model calculation of the nuclear surface-energy coefficient sigma the surface energy is defined as the energy loss of an uncharged, semiinfinite (inhomogeneous) two-component system compared to an infinite (homogeneous) system with the same particle asymmetry delta . Using the Thomas-Fermi model the calculations are performed for a series of systems with increasing delta , starting from symmetric matter ( delta =0) and extending beyond the drip line of the neutrons, until the system undergoes a phase transition to a homogeneous system. The results for the surface energy as well as for the neutron skin and for the surface diffuseness are compared to the macroscopic approach of the Droplet Model (DM), which turns out to be a good approximation for small asymmetries typical for the region of the valley of beta -stability. For larger asymmetries, close to the drip lines, terms of higher order than contained in the DM approach are no longer negligible. Beyond the drip lines the pressure of the ou...

  17. Potential energy surface of alanine polypeptide chains

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Yakubovich, Alexander V.; Solov'yov, Andrey V.

    2006-01-01

    The multidimensional potential energy surfaces of the peptide chains consisting of three and six alanine (Ala) residues have been studied with respect to the degrees of freedom related to the twist of these molecules relative to the peptide backbone (these degrees of freedom are responsible...

  18. Surface properties of Ti-6Al-4V alloy part I: Surface roughness and apparent surface free energy.

    Science.gov (United States)

    Yan, Yingdi; Chibowski, Emil; Szcześ, Aleksandra

    2017-01-01

    Titanium (Ti) and its alloys are the most often used implants material in dental treatment and orthopedics. Topography and wettability of its surface play important role in film formation, protein adhesion, following osseointegration and even duration of inserted implant. In this paper, we prepared Ti-6Al-4V alloy samples using different smoothing and polishing materials as well the air plasma treatment, on which contact angles of water, formamide and diiodomethane were measured. Then the apparent surface free energy was calculated using four different approaches (CAH, LWAB, O-W and Neumann's Equation of State). From LWAB approach the components of surface free energy were obtained, which shed more light on the wetting properties of samples surface. The surface roughness of the prepared samples was investigated with the help of optical profilometer and AFM. It was interesting whether the surface roughness affects the apparent surface free energy. It was found that both polar interactions the electron donor parameter of the energy and the work of water adhesion increased with decreasing roughness of the surfaces. Moreover, short time plasma treatment (1min) caused decrease in the surface hydrophilic character, while longer time (10min) treatment caused significant increase in the polar interactions and the work of water adhesion. Although Ti-6Al-4V alloy has been investigated many times, to our knowledge, so far no paper has been published in which surface roughness and changes in the surface free energy of the alloy were compared in the quantitative way in such large extent. This novel approach deliver better knowledge about the surface properties of differently smoothed and polished samples which may be helpful to facilitate cell adhesion, proliferation and mineralization. Therefore the results obtained present also potentially practical meaning. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. SURFACE SYMMETRY ENERGY OF NUCLEAR ENERGY DENSITY FUNCTIONALS

    Energy Technology Data Exchange (ETDEWEB)

    Nikolov, N; Schunck, N; Nazarewicz, W; Bender, M; Pei, J

    2010-12-20

    We study the bulk deformation properties of the Skyrme nuclear energy density functionals. Following simple arguments based on the leptodermous expansion and liquid drop model, we apply the nuclear density functional theory to assess the role of the surface symmetry energy in nuclei. To this end, we validate the commonly used functional parametrizations against the data on excitation energies of superdeformed band-heads in Hg and Pb isotopes, and fission isomers in actinide nuclei. After subtracting shell effects, the results of our self-consistent calculations are consistent with macroscopic arguments and indicate that experimental data on strongly deformed configurations in neutron-rich nuclei are essential for optimizing future nuclear energy density functionals. The resulting survey provides a useful benchmark for further theoretical improvements. Unlike in nuclei close to the stability valley, whose macroscopic deformability hangs on the balance of surface and Coulomb terms, the deformability of neutron-rich nuclei strongly depends on the surface-symmetry energy; hence, its proper determination is crucial for the stability of deformed phases of the neutron-rich matter and description of fission rates for r-process nucleosynthesis.

  20. Crystal Nucleation Using Surface-Energy-Modified Glass Substrates.

    Science.gov (United States)

    Nordquist, Kyle A; Schaab, Kevin M; Sha, Jierui; Bond, Andrew H

    2017-08-02

    Systematic surface energy modifications to glass substrates can induce nucleation and improve crystallization outcomes for small molecule active pharmaceutical ingredients (APIs) and proteins. A comparatively broad probe for function is presented in which various APIs, proteins, organic solvents, aqueous media, surface energy motifs, crystallization methods, form factors, and flat and convex surface energy modifications were examined. Replicate studies ( n ≥ 6) have demonstrated an average reduction in crystallization onset times of 52(4)% (alternatively 52 ± 4%) for acetylsalicylic acid from 91% isopropyl alcohol using two very different techniques: bulk cooling to 0 °C using flat surface energy modifications or microdomain cooling to 4 °C from the interior of a glass capillary having convex surface energy modifications that were immersed in the solution. For thaumatin and bovine pancreatic trypsin, a 32(2)% reduction in crystallization onset times was demonstrated in vapor diffusion experiments ( n ≥ 15). Nucleation site arrays have been engineered onto form factors frequently used in crystallization screening, including microscope slides, vials, and 96- and 384-well high-throughput screening plates. Nucleation using surface energy modifications on the vessels that contain the solutes to be crystallized adds a layer of useful variables to crystallization studies without requiring significant changes to workflows or instrumentation.

  1. Surface properties of Ti-6Al-4V alloy part I: Surface roughness and apparent surface free energy

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yingdi; Chibowski, Emil; Szcześ, Aleksandra, E-mail: aszczes@poczta.umcs.lublin.pl

    2017-01-01

    Titanium (Ti) and its alloys are the most often used implants material in dental treatment and orthopedics. Topography and wettability of its surface play important role in film formation, protein adhesion, following osseointegration and even duration of inserted implant. In this paper, we prepared Ti-6Al-4V alloy samples using different smoothing and polishing materials as well the air plasma treatment, on which contact angles of water, formamide and diiodomethane were measured. Then the apparent surface free energy was calculated using four different approaches (CAH, LWAB, O-W and Neumann's Equation of State). From LWAB approach the components of surface free energy were obtained, which shed more light on the wetting properties of samples surface. The surface roughness of the prepared samples was investigated with the help of optical profilometer and AFM. It was interesting whether the surface roughness affects the apparent surface free energy. It was found that both polar interactions the electron donor parameter of the energy and the work of water adhesion increased with decreasing roughness of the surfaces. Moreover, short time plasma treatment (1 min) caused decrease in the surface hydrophilic character, while longer time (10 min) treatment caused significant increase in the polar interactions and the work of water adhesion. Although Ti-6Al-4V alloy has been investigated many times, to our knowledge, so far no paper has been published in which surface roughness and changes in the surface free energy of the alloy were compared in the quantitative way in such large extent. This novel approach deliver better knowledge about the surface properties of differently smoothed and polished samples which may be helpful to facilitate cell adhesion, proliferation and mineralization. Therefore the results obtained present also potentially practical meaning. - Highlights: • Surface of five Ti-6Al-4V alloy samples were smoothed and polished successively. • The

  2. Energy redistribution in diatomic molecules on surfaces

    International Nuclear Information System (INIS)

    Asscher, M.; Somorjai, G.A.

    1984-04-01

    Translational and internal degrees of freedom of a scattered beam of NO molecules from a Pt(111) single crystal surface were measured as a function of scattering angle and crystal temperature in the range 450 to 1250K. None of the three degrees of freedom were found to fully accommodate to the crystal temperature, the translational degree being the most accommodated and the rotational degree of freedom the least. A precursor state model is suggested to account for the incomplete accommodation of translational and vibrational degrees of freedom as a function of crystal temperature and incident beam energy. The vibrational accommodation is further discussed in terms of a competition between desorption and vibrational excitation processes, thus providing valuable information on the interaction between vibrationally excited molecules and surfaces. Energy transfer into rotational degrees of freedom is qualitatively discussed

  3. A simulation of laser energy absorption by nanowired surface

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, Miguel F.S.; Ramos, Alexandre F., E-mail: miguel.vasconcelos@usp.br, E-mail: alex.ramos@usp.br [Universidade de São Paulo (USP), SP (Brazil). Escola de Artes, Ciências e Humanidades

    2017-07-01

    Despite recent advances on research about laser inertial fusion energy, to increase the portion of energy absorbed by the target's surface from lasers remains as an important challenge. The plasma formed during the initial instants of laser arrival shields the target and prevents the absorption of laser energy by the deeper layers of the material. One strategy to circumvent that effect is the construction of targets whose surfaces are populated with nanowires. The nanowired surfaces have increased absorption of laser energy and constitutes a promising pathway for enhancing laser-matter coupling. In our work we present the results of simulations aiming to investigate how target's geometrical properties might contribute for maximizing laser energy absorption by material. Simulations have been carried out using the software FLASH, a multi-physics platform developed by researchers from the University of Chicago, written in FORTRAN 90 and Python. Different tools for generating target's geometry and analysis of results were developed using Python. Our results show that a nanowired surfaces has an increased energy absorption when compared with non wired surface. The software for visualization developed in this work also allowed an analysis of the spatial dynamics of the target's temperature, electron density, ionization levels and temperature of the radiation emitted by it. (author)

  4. A simulation of laser energy absorption by nanowired surface

    International Nuclear Information System (INIS)

    Vasconcelos, Miguel F.S.; Ramos, Alexandre F.

    2017-01-01

    Despite recent advances on research about laser inertial fusion energy, to increase the portion of energy absorbed by the target's surface from lasers remains as an important challenge. The plasma formed during the initial instants of laser arrival shields the target and prevents the absorption of laser energy by the deeper layers of the material. One strategy to circumvent that effect is the construction of targets whose surfaces are populated with nanowires. The nanowired surfaces have increased absorption of laser energy and constitutes a promising pathway for enhancing laser-matter coupling. In our work we present the results of simulations aiming to investigate how target's geometrical properties might contribute for maximizing laser energy absorption by material. Simulations have been carried out using the software FLASH, a multi-physics platform developed by researchers from the University of Chicago, written in FORTRAN 90 and Python. Different tools for generating target's geometry and analysis of results were developed using Python. Our results show that a nanowired surfaces has an increased energy absorption when compared with non wired surface. The software for visualization developed in this work also allowed an analysis of the spatial dynamics of the target's temperature, electron density, ionization levels and temperature of the radiation emitted by it. (author)

  5. Surface energy budget and turbulent fluxes at Arctic terrestrial sites

    Science.gov (United States)

    Grachev, Andrey; Persson, Ola; Uttal, Taneil; Konopleva-Akish, Elena; Crepinsek, Sara; Cox, Christopher; Fairall, Christopher; Makshtas, Alexander; Repina, Irina

    2017-04-01

    Determination of the surface energy budget (SEB) and all SEB components at the air-surface interface are required in a wide variety of applications including atmosphere-land/snow simulations and validation of the surface fluxes predicted by numerical models over different spatial and temporal scales. Here, comparisons of net surface energy budgets at two Arctic sites are made using long-term near-continuous measurements of hourly averaged surface fluxes (turbulent, radiation, and soil conduction). One site, Eureka (80.0 N; Nunavut, Canada), is located in complex topography near a fjord about 200 km from the Arctic Ocean. The other site, Tiksi (71.6 N; Russian East Siberia), is located on a relatively flat coastal plain less than 1 km from the shore of Tiksi Bay, a branch of the Arctic Ocean. We first analyzed diurnal and annual cycles of basic meteorological parameters and key SEB components at these locations. Although Eureka and Tiksi are located on different continents and at different latitudes, the annual course of the surface meteorology and SEB components are qualitatively similar. Surface energy balance closure is a formulation of the conservation of energy principle. Our direct measurements of energy balance for both Arctic sites show that the sum of the turbulent sensible and latent heat fluxes and the ground (conductive) heat flux systematically underestimate the net radiation by about 25-30%. This lack of energy balance closure is a fundamental and pervasive problem in micrometeorology. We discuss a variety of factors which may be responsible for the lack of SEB closure. In particular, various storage terms (e.g., air column energy storage due to radiative and/or sensible heat flux divergence, ground heat storage above the soil flux plate, energy used in photosynthesis, canopy biomass heat storage). For example, our observations show that the photosynthesis storage term is relatively small (about 1-2% of the net radiation), but about 8-12% of the

  6. Low Energy Nuclear Reaction Products at Surfaces

    Science.gov (United States)

    Nagel, David J.

    2008-03-01

    This paper examines the evidence for LENR occurring on or very near to the surface of materials. Several types of experimental indications for LENR surface reactions have been reported and will be reviewed. LENR result in two types of products, energy and the appearance of new elements. The level of instantaneous power production can be written as the product of four factors: (1) the total area of the surface on which the reactions can occur, (2) the fraction of the area that is active at any time, (3) the reaction rate, that is, the number of reactions per unit active area per second, and (4) the energy produced per reaction. Each of these factors, and their limits, are reviewed. A graphical means of relating these four factors over their wide variations has been devised. The instantaneous generation of atoms of new elements can also be written as the product of the first three factors and the new elemental mass produced per reaction. Again, a graphical means of presenting the factors and their results over many orders of magnitude has been developed.

  7. Theoretical studies of potential energy surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Harding, L.B. [Argonne National Laboratory, IL (United States)

    1993-12-01

    The goal of this program is to calculate accurate potential energy surfaces (PES) for both reactive and nonreactive systems. To do this the electronic Schrodinger equation must be solved. Our approach to this problem starts with multiconfiguration self-consistent field (MCSCF) reference wavefunctions. These reference wavefunctions are designed to be sufficiently flexible to accurately describe changes in electronic structure over a broad range of geometries. Electron correlation effects are included via multireference, singles and doubles configuration interaction (MRSDCI) calculations. With this approach, the authors are able to provide useful predictions of the energetics for a broad range of systems.

  8. Signal Attenuation Curve for Different Surface Detector Arrays

    Science.gov (United States)

    Vicha, J.; Travnicek, P.; Nosek, D.; Ebr, J.

    2014-06-01

    Modern cosmic ray experiments consisting of large array of particle detectors measure the signals of electromagnetic or muon components or their combination. The correction for an amount of atmosphere passed is applied to the surface detector signal before its conversion to the shower energy. Either Monte Carlo based approach assuming certain composition of primaries or indirect estimation using real data and assuming isotropy of arrival directions can be used. Toy surface arrays of different sensitivities to electromagnetic and muon components are assumed in MC simulations to study effects imposed on attenuation curves for varying composition or possible high energy anisotropy. The possible sensitivity of the attenuation curve to the mass composition is also tested for different array types focusing on a future apparatus that can separate muon and electromagnetic component signals.

  9. Health impacts of different energy sources

    International Nuclear Information System (INIS)

    1982-01-01

    Energy is needed to sustain the economy, health and welfare of nations. As a consequence of this, energy consumption figures are frequently used as an index of a nation's advancement. As a result of the global energy crisis, almost every nation has had to develop all its available energy resources and plan its future use of energy. The planners of national and international energy policies are however often faced with a problem of 'public acceptance' arising from the potential health and environmental impacts of developing energy resources. The public's desire to preserve the quality of man's health and his environment frequently results in opposition to many industrial innovations, including the generation and use of energy. Reliable, quantitative data and information are needed on the risks to health and the environment of different contemporary energy systems, to improve public understanding, and to serve as the basis from which national planners can choose between different energy supply options. With the exception of nuclear energy, even in technologically advanced countries little systematic research and development has been done on the quantitative assessment of the effects on health and the environment of the conventional energy sources. The need for this information has only been realized over the past decade as the climate and environment in many regions of the world has deteriorated with the unabated release of pollutants from factories and energy generating plants in particular. A number of countries have started national environmental health research programmes to monitor and regulate toxic emissions from industry and energy plants. Energy-related environmental health research has been supported and co-ordinated by various international organizations such as the International Atomic Energy Agency (IAEA), World Health Organization (WHO) and United Nations Environment Programme (UNEP). WHO has supported expert reviews on the potential health risks posed

  10. Interdependence of different symmetry energy elements

    Science.gov (United States)

    Mondal, C.; Agrawal, B. K.; De, J. N.; Samaddar, S. K.; Centelles, M.; Viñas, X.

    2017-08-01

    Relations between the nuclear symmetry energy coefficient and its density derivatives are derived. The relations hold for a class of interactions with quadratic momentum dependence and a power-law density dependence. The structural connection between the different symmetry energy elements as obtained seems to be followed by almost all reasonable nuclear energy density functionals, both relativistic and nonrelativistic, suggesting a universality in the correlation structure. This, coupled with known values of some well-accepted constants related to nuclear matter, helps in constraining values of different density derivatives of the nuclear symmetry energy, shedding light on the isovector part of the nuclear interaction.

  11. Wettability transition of laser textured brass surfaces inside different mediums

    Science.gov (United States)

    Yan, Huangping; Abdul Rashid, Mohamed Raiz B.; Khew, Si Ying; Li, Fengping; Hong, Minghui

    2018-01-01

    Hydrophobic surface on brass has attracted intensive attention owing to its importance in scientific research and practical applications. Laser texturing provides a simple and promising method to achieve it. Reducing wettability transition time from hydrophilicity to hydrophobicity or superhydrophobicity remains a challenge. Herein, wettability transition of brass surfaces with hybrid micro/nano-structures fabricated by laser texturing was investigated by immersing the samples inside different mediums. Scanning electron microscopy, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy and surface contact angle measurement were employed to characterize surface morphology, chemical composition and wettability of the fabricated surfaces of brass samples. Wettability transition time from hydrophilicity to hydrophobicity was shortened by immersion into isopropyl alcohol for a period of 3 h as a result of the absorption and accumulation of organic substances on the textured brass surface. When the textured brass sample was immersed into sodium bicarbonate solution, flower-like structures on the sample surface played a key role in slowing down wettability transition. Moreover, it had the smallest steady state contact angle as compared to the others. This study provides a facile method to construct textured surfaces with tunable wetting behaviors and effectively extend the industrial applications of brass.

  12. Urban Surface Radiative Energy Budgets Determined Using Aircraft Scanner Data

    Science.gov (United States)

    Luvall, Jeffrey C.; Quattrochi, Dale A.; Rickman, Doug L.; Estes, Maury G.; Arnold, James E. (Technical Monitor)

    2002-01-01

    It is estimated that by the year 2025, 80% of the world's population will live in cities. The extent of these urban areas across the world can be seen in an image of city lights from the Defense Meteorological Satellite Program. In many areas of North America and Europe, it is difficult to separate individual cities because of the dramatic growth and sprawl of urbanized areas. This conversion of the natural landscape vegetation into man-made urban structures such as roads and buildings drastically alter the regional surface energy budgets, hydrology, precipitation patterns, and meteorology. One of the earliest recognized and measured phenomena of urbanization is the urban heat island (UHI) which was reported as early as 1833 for London and 1862 for Paris. The urban heat island results from the energy that is absorbed by man-made materials during the day and is released at night resulting in the heating of the air within the urban area. The magnitude of the air temperature difference between the urban and surrounding countryside is highly dependent on the structure of the urban area, amount of solar immolation received during the day, and atmospheric conditions during the night. These night time air temperature differences can be in the range of 2 to 5 C. or greater. Although day time air temperature differences between urban areas and the countryside exists during the day, atmospheric mixing and stability reduce the magnitude. This phenomena is not limited to large urban areas, but also occurs in smaller metropolitan areas. The UHI has significant impacts on the urban air quality, meteorology, energy use, and human health. The UPI can be mitigated through increasing the amount of vegetation and modification of urban surfaces using high albedo materials for roofs and paved surfaces. To understand why the urban heat island phenomenon exists it is useful to define the surface in terms of the surface energy budget. Surface temperature and albedo is a major component of

  13. Accuracy Assessment of Different Digital Surface Models

    Directory of Open Access Journals (Sweden)

    Ugur Alganci

    2018-03-01

    Full Text Available Digital elevation models (DEMs, which can occur in the form of digital surface models (DSMs or digital terrain models (DTMs, are widely used as important geospatial information sources for various remote sensing applications, including the precise orthorectification of high-resolution satellite images, 3D spatial analyses, multi-criteria decision support systems, and deformation monitoring. The accuracy of DEMs has direct impacts on specific calculations and process chains; therefore, it is important to select the most appropriate DEM by considering the aim, accuracy requirement, and scale of each study. In this research, DSMs obtained from a variety of satellite sensors were compared to analyze their accuracy and performance. For this purpose, freely available Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER 30 m, Shuttle Radar Topography Mission (SRTM 30 m, and Advanced Land Observing Satellite (ALOS 30 m resolution DSM data were obtained. Additionally, 3 m and 1 m resolution DSMs were produced from tri-stereo images from the SPOT 6 and Pleiades high-resolution (PHR 1A satellites, respectively. Elevation reference data provided by the General Command of Mapping, the national mapping agency of Turkey—produced from 30 cm spatial resolution stereo aerial photos, with a 5 m grid spacing and ±3 m or better overall vertical accuracy at the 90% confidence interval (CI—were used to perform accuracy assessments. Gross errors and water surfaces were removed from the reference DSM. The relative accuracies of the different DSMs were tested using a different number of checkpoints determined by different methods. In the first method, 25 checkpoints were selected from bare lands to evaluate the accuracies of the DSMs on terrain surfaces. In the second method, 1000 randomly selected checkpoints were used to evaluate the methods’ accuracies for the whole study area. In addition to the control point approach, vertical cross

  14. Surface sterilization by low energy electron beams

    International Nuclear Information System (INIS)

    Sekiguchi, Masayuki; Tabei, Masae

    1989-01-01

    The germicidal effectiveness of low energy electron beams (175 KV) against bacterial cells was investigated. The dry spores of Bacillus pumilus ATCC 27142 and Bacillus globigii ATCC 9372 inoculated on carrier materials and irradiated by gamma rays showed the exponential type of survival curves whereas they showed sigmoidal ones when exposed to low energy electron beams. When similarly irradiated, the wet spores inoculated on membrane filter showed the same survival curves as the dry spores inoculated on carrier materials. The wet vegetative cells of Escherichia coli ATCC 25922 showed exponential curves when exposed to gamma and electron beam irradiation. Low energy electron beams in air showed little differences from nitrogen stream in their germicidal effectiveness against dry spores of B. pumilus. The D values of B. pumilus spores inoculated on metal plates decreased as the amounts of backscattering electrons from the plates increased. There was adequate correlation between the D value (linear region of survival curve), average D value (6D/6) and 1% survival dose and backscattering factor. Depth dose profile and backscatterig dose of low energy electron beams were measured by radiochromic dye film dosimeter (RCD). These figures were not always in accord with the observed germicidal effectiveness against B. pumilus spores because of varying thickness of RCD and spores inoculated on carrier material. The dry spores were very thin and this thinness was useful in evaluating the behavior of low energy electrons. (author)

  15. Tantalum surface oxidation: Bond relaxation, energy entrapment, and electron polarization

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yongling [Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education), Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Faculty of Materials Science and Engineering, Xiangtan University, Hunan 411105 (China); Bo, Maolin [Yangtze Normal University, College of Mechanical and Electrical Engineering, Chongqing 408100 (China); Wang, Yan [School of Information and Electronic Engineering, Hunan University of Science and Technology, Hunan 411201 (China); Liu, Yonghui [Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education), Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Faculty of Materials Science and Engineering, Xiangtan University, Hunan 411105 (China); Sun, Chang Q. [NOVITAS, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Huang, Yongli, E-mail: huangyongli@xtu.edu.cn [Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education), Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Faculty of Materials Science and Engineering, Xiangtan University, Hunan 411105 (China)

    2017-02-28

    Graphical abstract: The bond, electron and energy relaxation result in core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Highlights: • Increasing the oxygen coverage lowers the adsorption energy associated with lattice reconstruction. • Electrons transfer from Ta surface atoms to sp-hydrated oxygen, creating dipole moment that decreases the work function. • Oxygen chemisorption modified valence density-of-state (DOS) for Ta with four excessive DOS features: O−Ta bonding, O{sup 2−} lone pairs, Ta+ electron holes, and the lone-pair polarized Ta dipoles. • The bond, electron and energy relaxation between surface undercoordinated atoms are responsible for core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Abstract: A combination of photoelectron spectrometric analysis and density functional theory calculations has enabled reconciliation of the bond-energy-electron relaxation for the Ta(100, 110, 111) surfaces chemisorbed with oxygen at different coverages. Results show that increasing oxygen coverage lowers the adsorption energy associated with lattice reconstruction. Valence electrons transfer from Ta surface atoms to oxygen to create four excessive DOS features in terms of O−Ta bonding, lone pairs of oxygen, Ta{sup +} electron holes, and polarized Ta dipoles. Oxidation proceeds in the following dynamics: oxygen gets electrons from two neighboring Ta atoms left behind Ta{sup +}; the sp{sup 3}-orbital hybridization takes place with additional two electron lone pairs, the lone pairs polarize the other two Ta neighbors becoming dipoles. X-ray photoelectron spectral analysis results in the 4f binding energy of an isolated Ta atom and its shift upon bond formation and oxidation. Exercises provide not only a promising numerical approach for the quantitative information about the bond and electronic behavior but also consistent

  16. Tantalum surface oxidation: Bond relaxation, energy entrapment, and electron polarization

    International Nuclear Information System (INIS)

    Guo, Yongling; Bo, Maolin; Wang, Yan; Liu, Yonghui; Sun, Chang Q.; Huang, Yongli

    2017-01-01

    Graphical abstract: The bond, electron and energy relaxation result in core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Highlights: • Increasing the oxygen coverage lowers the adsorption energy associated with lattice reconstruction. • Electrons transfer from Ta surface atoms to sp-hydrated oxygen, creating dipole moment that decreases the work function. • Oxygen chemisorption modified valence density-of-state (DOS) for Ta with four excessive DOS features: O−Ta bonding, O"2"− lone pairs, Ta+ electron holes, and the lone-pair polarized Ta dipoles. • The bond, electron and energy relaxation between surface undercoordinated atoms are responsible for core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Abstract: A combination of photoelectron spectrometric analysis and density functional theory calculations has enabled reconciliation of the bond-energy-electron relaxation for the Ta(100, 110, 111) surfaces chemisorbed with oxygen at different coverages. Results show that increasing oxygen coverage lowers the adsorption energy associated with lattice reconstruction. Valence electrons transfer from Ta surface atoms to oxygen to create four excessive DOS features in terms of O−Ta bonding, lone pairs of oxygen, Ta"+ electron holes, and polarized Ta dipoles. Oxidation proceeds in the following dynamics: oxygen gets electrons from two neighboring Ta atoms left behind Ta"+; the sp"3-orbital hybridization takes place with additional two electron lone pairs, the lone pairs polarize the other two Ta neighbors becoming dipoles. X-ray photoelectron spectral analysis results in the 4f binding energy of an isolated Ta atom and its shift upon bond formation and oxidation. Exercises provide not only a promising numerical approach for the quantitative information about the bond and electronic behavior but also consistent insight into the

  17. Properties of water surface discharge at different pulse repetition rates

    International Nuclear Information System (INIS)

    Ruma,; Yoshihara, K.; Hosseini, S. H. R.; Sakugawa, T.; Akiyama, H.; Akiyama, M.; Lukeš, P.

    2014-01-01

    The properties of water surface discharge plasma for variety of pulse repetition rates are investigated. A magnetic pulse compression (MPC) pulsed power modulator able to deliver pulse repetition rates up to 1000 Hz, with 0.5 J per pulse energy output at 25 kV, was used as the pulsed power source. Positive pulse with a point-to-plane electrode configuration was used for the experiments. The concentration and production yield of hydrogen peroxide (H 2 O 2 ) were quantitatively measured and orange II organic dye was treated, to evaluate the chemical properties of the discharge reactor. Experimental results show that the physical and chemical properties of water surface discharge are not influenced by pulse repetition rate, very different from those observed for under water discharge. The production yield of H 2 O 2 and degradation rate per pulse of the dye did not significantly vary at different pulse repetition rates under a constant discharge mode on water surface. In addition, the solution temperature, pH, and conductivity for both water surface and underwater discharge reactors were measured to compare their plasma properties for different pulse repetition rates. The results confirm that surface discharge can be employed at high pulse repetition rates as a reliable and advantageous method for industrial and environmental decontamination applications.

  18. Energy Absorbing Effectiveness – Different Approaches

    Directory of Open Access Journals (Sweden)

    Kotełko Maria

    2018-03-01

    Full Text Available In the paper the study of different crashworthiness indicators used to evaluate energy absorbing effectiveness of thin-walled energy absorbers is presented. Several different indicators are used to assess an effectiveness of two types of absorbing structures, namely thin-walled prismatic column with flaws and thin-walled prismatic frustum (hollow or foam filled in both cases subjected to axial compressive impact load. The indicators are calculated for different materials and different geometrical parameters. The problem of selection of the most appropriate and general indicators is discussed.

  19. The Global Energy Balance Archive (GEBA): A database for the worldwide measured surface energy fluxes

    Science.gov (United States)

    Wild, Martin; Ohmura, Atsumu; Schär, Christoph; Müller, Guido; Hakuba, Maria Z.; Mystakidis, Stefanos; Arsenovic, Pavle; Sanchez-Lorenzo, Arturo

    2017-02-01

    The Global Energy Balance Archive (GEBA) is a database for the worldwide measured energy fluxes at the Earth's surface. GEBA is maintained at ETH Zurich (Switzerland) and has been founded in the 1980s by Prof. Atsumu Ohmura. It has continuously been updated and currently contains around 2500 stations with 500`000 monthly mean entries of various surface energy balance components. Many of the records extend over several decades. The most widely measured quantity available in GEBA is the solar radiation incident at the Earth's surface ("global radiation"). The data sources include, in addition to the World Radiation Data Centre (WRDC) in St. Petersburg, data reports from National Weather Services, data from different research networks (BSRN, ARM, SURFRAD), data published in peer-reviewed publications and data obtained through personal communications. Different quality checks are applied to check for gross errors in the dataset. GEBA is used in various research applications, such as for the quantification of the global energy balance and its spatiotemporal variation, or for the estimation of long-term trends in the surface fluxes, which enabled the detection of multi-decadal variations in surface solar radiation, known as "global dimming" and "brightening". GEBA is further extensively used for the evaluation of climate models and satellite-derived surface flux products. On a more applied level, GEBA provides the basis for engineering applications in the context of solar power generation, water management, agricultural production and tourism. GEBA is publicly accessible over the internet via www.geba.ethz.ch.

  20. Universal binding energy relation for cleaved and structurally relaxed surfaces

    International Nuclear Information System (INIS)

    Srirangarajan, Aarti; Datta, Aditi; Gandi, Appala Naidu; Ramamurty, U; Waghmare, U V

    2014-01-01

    The universal binding energy relation (UBER), derived earlier to describe the cohesion between two rigid atomic planes, does not accurately capture the cohesive properties when the cleaved surfaces are allowed to relax. We suggest a modified functional form of UBER that is analytical and at the same time accurately models the properties of surfaces relaxed during cleavage. We demonstrate the generality as well as the validity of this modified UBER through first-principles density functional theory calculations of cleavage in a number of crystal systems. Our results show that the total energies of all the relaxed surfaces lie on a single (universal) energy surface, that is given by the proposed functional form which contains an additional length-scale associated with structural relaxation. This functional form could be used in modelling the cohesive zones in crack growth simulation studies. We find that the cohesive law (stress–displacement relation) differs significantly in the case where cracked surfaces are allowed to relax, with lower peak stresses occurring at higher displacements. (paper)

  1. Universal binding energy relation for cleaved and structurally relaxed surfaces.

    Science.gov (United States)

    Srirangarajan, Aarti; Datta, Aditi; Gandi, Appala Naidu; Ramamurty, U; Waghmare, U V

    2014-02-05

    The universal binding energy relation (UBER), derived earlier to describe the cohesion between two rigid atomic planes, does not accurately capture the cohesive properties when the cleaved surfaces are allowed to relax. We suggest a modified functional form of UBER that is analytical and at the same time accurately models the properties of surfaces relaxed during cleavage. We demonstrate the generality as well as the validity of this modified UBER through first-principles density functional theory calculations of cleavage in a number of crystal systems. Our results show that the total energies of all the relaxed surfaces lie on a single (universal) energy surface, that is given by the proposed functional form which contains an additional length-scale associated with structural relaxation. This functional form could be used in modelling the cohesive zones in crack growth simulation studies. We find that the cohesive law (stress-displacement relation) differs significantly in the case where cracked surfaces are allowed to relax, with lower peak stresses occurring at higher displacements.

  2. Computed potential energy surfaces for chemical reactions

    Science.gov (United States)

    Walch, Stephen P.

    1988-01-01

    The minimum energy path for the addition of a hydrogen atom to N2 is characterized in CASSCF/CCI calculations using the (4s3p2d1f/3s2p1d) basis set, with additional single point calculations at the stationary points of the potential energy surface using the (5s4p3d2f/4s3p2d) basis set. These calculations represent the most extensive set of ab initio calculations completed to date, yielding a zero point corrected barrier for HN2 dissociation of approx. 8.5 kcal mol/1. The lifetime of the HN2 species is estimated from the calculated geometries and energetics using both conventional Transition State Theory and a method which utilizes an Eckart barrier to compute one dimensional quantum mechanical tunneling effects. It is concluded that the lifetime of the HN2 species is very short, greatly limiting its role in both termolecular recombination reactions and combustion processes.

  3. Energy consumption for different greenhouse constructions

    Energy Technology Data Exchange (ETDEWEB)

    Djevic, M.; Dimitrijevic, A. [Department for Agricultural Engineering, University of Belgrade, Faculty of Agriculture, Nemanjina 6, 11080 Belgrade (RS)

    2009-09-15

    In this paper the influence of greenhouse construction on energy efficiency in winter lettuce production was estimated for four different double plastic covered greenhouses in Serbia region. Plastic coverings were introduced in this region as a mean of making the plant production more energy efficient. Additionally, as a means of lowering energy consumption, tunnel structures were proposed. In order to see whether the greenhouse structure influences energy consumption, four different double plastic covered greenhouses. Two tunnel types, 9 x 58 m and 8 x 25 m, one gutter-connected structure and multi-span plastic covered greenhouse. The gutter-connected structure was 2 x 7 m wide and 39 m long while the multi-span structure was 20 x 6.4 m wide and 42 m long. On the basis of lettuce production output and the energy input, specific energy input, energy output-input ratio and energy productivity were estimated. Results show that the lowest energy consumption was obtained for multi-span greenhouse, 9.76 MJ/m{sup 2}. The highest energy consumption was obtained in tunnel, 9 x 58 m, 13.93 MJ/m{sup 2}. The highest value for output-input ratio was calculated for multi-span greenhouse (0.29), followed by gutter-connected greenhouse (0.21), tunnel 9 x 58 m (0.17) and tunnel, 8 x 25 m (0.15). Results also show that energy productivity can be higher if multi-span greenhouse structures are used. (author)

  4. The surface-forming energy release rate versus the local energy release rate

    OpenAIRE

    Xiao, Si; Wang, He-ling; Landis, Chad M; Hwang, Keh-Chih; Liu, Bin

    2016-01-01

    This paper identifies two ways to extract the energy (or power) flowing into a crack tip during propagation based on the power balance of areas enclosed by a stationary contour and a comoving contour. It is very interesting to find a contradiction that two corresponding energy release rates (ERRs), a surface-forming ERR and a local ERR, are different when stress singularity exists at a crack tip. Besides a rigorous mathematical interpretation, we deduce that the stress singularity leads to an...

  5. RELATIONSHIP BETWEEN FOAMING BEHAVIOR AND SURFACE ENERGY OF ASPHALT BINDER

    Directory of Open Access Journals (Sweden)

    Jian-ping Xu

    2017-12-01

    Full Text Available To solve the problem of insufficiency in microscopic performance of foamed asphalt binder, surface energy theory was utilized to analyze the foaming behavior and wettability of asphalt binder. Based on the surface energy theory, the Wilhelmy plate method and universal sorption device method were employed to measure the surface energy components of asphalt binders and aggregates, respectively. Combined with the traditional evaluation indictor for foamed asphalt, the relationship between the foaming property and surface energy of asphalt binder was analyzed. According to the surface energy components, the wettability of asphalt binder to aggregate was calculated to verify the performance of foamed asphalt mixture. Results indicate that the foaming behavior of asphalt will be influenced by surface energy, which will increase with the decline of surface energy. In addition, the surface energy of asphalt binder significantly influences the wettability of asphalt binder to aggregates. Meanwhile, there is an inversely proportional relationship between surface energy of asphalt binder and wettability. Therefore, it can be demonstrated that surface energy is a good indictor which can be used to evaluate the foaming behavior of the asphalt binder. And it is suggested to choose the asphalt binder with lower surface energy in the process of design of foamed asphalt mixture.

  6. Comparison of surface energy fluxes with satellite-derived surface energy flux estimates from a shrub-steppe

    International Nuclear Information System (INIS)

    Kirkham, R.R.

    1993-12-01

    This thesis relates the components of the surface energy balance (i.e., net radiation, sensible and latent heat flux densities, soil heat flow) to remotely sensed data for native vegetation in a semi-arid environment. Thematic mapper data from Landsat 4 and 5 were used to estimate net radiation, sensible heat flux (H), and vegetation amount. Several sources of ground truth were employed. They included soil water balance using the neutron thermalization method and weighing lysimeters, and the measurement of energy fluxes with the Bowen ratio energy balance (BREB) technique. Sensible and latent heat flux were measured at four sites on the U.S. Department of Energy's Hanford Site using a weighing lysimeter and/or BREB stations. The objective was to calibrate an aerodynamic transport equation that related H to radiant surface temperature. The transport equation was then used with Landsat thermal data to generate estimates of H and compare these estimates against H values obtained with BREB/lysimeters at the time of overflight. Landsat and surface meteorologic data were used to estimate the radiation budget terms at the surface. Landsat estimates of short-wave radiation reflected from the surface correlate well with reflected radiation measured using inverted Eppley pyranometers. Correlation of net radiation estimates determined from satellite data, pyranometer, air temperature, and vapor pressure compared to net radiometer values obtained at time of overflight were excellent for a single image, but decrease for multiple images. Soil heat flux, G T , is a major component of the energy balance in arid systems and G T generally decreases as vegetation cover increases. Normalized difference vegetation index (NDVI) values generated from Landsat thermatic mapper data were representative of field observations of the presence of green vegetation, but it was not possible to determine a single relationship between NDVI and G T for all sites

  7. Comment on 'Modelling of surface energies of elemental crystals'

    International Nuclear Information System (INIS)

    Li Jinping; Luo Xiaoguang; Hu Ping; Dong Shanliang

    2009-01-01

    Jiang et al (2004 J. Phys.: Condens. Matter 16 521) present a model based on the traditional broken-bond model for predicting surface energies of elemental crystals. It is found that bias errors can be produced in calculating the coordination numbers of surface atoms, especially in the prediction of high-Miller-index surface energies. (comment)

  8. How important is getting the land surface energy exchange correct in WRF for wind energy forecasting?

    Science.gov (United States)

    Wharton, S.; Simpson, M.; Osuna, J. L.; Newman, J. F.; Biraud, S.

    2013-12-01

    Wind power forecasting is plagued with difficulties in accurately predicting the occurrence and intensity of atmospheric conditions at the heights spanned by industrial-scale turbines (~ 40 to 200 m above ground level). Better simulation of the relevant physics would enable operational practices such as integration of large fractions of wind power into power grids, scheduling maintenance on wind energy facilities, and deciding design criteria based on complex loads for next-generation turbines and siting. Accurately simulating the surface energy processes in numerical models may be critically important for wind energy forecasting as energy exchange at the surface strongly drives atmospheric mixing (i.e., stability) in the lower layers of the planetary boundary layer (PBL), which in turn largely determines wind shear and turbulence at heights found in the turbine rotor-disk. We hypothesize that simulating accurate a surface-atmosphere energy coupling should lead to more accurate predictions of wind speed and turbulence at heights within the turbine rotor-disk. Here, we tested 10 different land surface model configurations in the Weather Research and Forecasting (WRF) model including Noah, Noah-MP, SSiB, Pleim-Xiu, RUC, and others to evaluate (1) the accuracy of simulated surface energy fluxes to flux tower measurements, (2) the accuracy of forecasted wind speeds to observations at rotor-disk heights, and (3) the sensitivity of forecasting hub-height rotor disk wind speed to the choice of land surface model. WRF was run for four, two-week periods covering both summer and winter periods over the Southern Great Plains ARM site in Oklahoma. Continuous measurements of surface energy fluxes and lidar-based wind speed, direction and turbulence were also available. The SGP ARM site provided an ideal location for this evaluation as it centrally located in the wind-rich Great Plains and multi-MW wind farms are rapidly expanding in the area. We found significant differences in

  9. Surface wind energy trends near Taiwan in winter since 1871

    Directory of Open Access Journals (Sweden)

    Lei Zhang

    2017-01-01

    Full Text Available The tropical surface wind speed in boreal winter reaches a maximum near Taiwan. This stable wind resource may be used for future clean energy development. How this surface wind energy source has changed in past 141 years is investigated using the 20th century reanalysis dataset and CMIP5 models. Our observational analysis shows that the surface wind speed experienced a weakening trend in the past 141 years (1871 - 2010. The average decreasing rate is around -1.4 m s-1 per century. The decrease is primarily attributed to the relative sea surface temperature (SST cooling in the subtropical North Pacific, which forces a large-scale low-level anti-cyclonic circulation anomaly in situ and is thus responsible for the southerly trend near Taiwan. The relative SST trend pattern is attributed mainly to the greenhouse gas effect associated with anthropogenic activities. The southerly trend near Taiwan is more pronounced in the boreal winter than in summer. Such seasonal difference is attributed to the reversed seasonal mean wind, which promotes more efficient positive feedback in the boreal winter. The CMIP5 historical run analysis reveals that climate models capture less SST warming and large-scale anti-cyclonic circulation in the subtropical North Pacific, but the simulated weakening trend of the surface wind speed near Taiwan is too small.

  10. The energy balance of the earth's surface : a practical approach

    NARCIS (Netherlands)

    Bruin, de H.A.R.

    1982-01-01

    This study is devoted to the energy balance of the earth's surface with a special emphasis on practical applications. A simple picture of the energy exchange processes that take place at the ground is the following. Per unit time and area an amount of radiant energy is supplied to the surface. This

  11. Fowler's approximation for the surface tension and surface energy of Lennard-Jones fluids revisited

    International Nuclear Information System (INIS)

    Mulero, A; Galan, C; Cuadros, F

    2003-01-01

    We present a detailed study of the validity of Fowler's approximation for calculating the surface tension and the surface energy of Lennard-Jones fluids. To do so, we consider three different explicit analytical expressions for the radial distribution function (RDF), including one proposed by our research group, together with very accurate expressions for the liquid and vapour densities, also proposed by our group. The calculation of the surface tension from the direct correlation function using both the Percus-Yevick and the hypernetted-chain approximations is also considered. Finally, our results are compared with those obtained by other authors by computer simulations or through relevant theoretical approximations. In particular, we consider the analytical expression proposed by Kalikmanov and Hofmans (1994 J. Phys.: Condens. Matter 6 2207-14) for the surface tension. Our results indicate that the values for the surface energy in Fowler's approximation obtained by other authors are adequate, and can be calculated from the RDF models. For the surface tension, however, the values considered as valid in previous works seem to be incorrect. The correct values can be obtained from our model for the RDF or from the Kalikmanov and Hofmans expression with suitable inputs

  12. Energy Accommodation from Surface Catalyzed Reactions in Air Plasmas

    Data.gov (United States)

    National Aeronautics and Space Administration — Understanding energy transport at the gas-surface interface between catalytic/reacting surfaces exposed to highly dissociated plasmas remains a significant research...

  13. Coulomb energy differences in mirror nuclei

    International Nuclear Information System (INIS)

    Lenzi, Silvia M

    2006-01-01

    By comparing the excitation energies of analogue states in mirror nuclei, several nuclear structure properties can be studied as a function of the angular momentum up to high spin states. They can be described in the shell model framework by including electromagnetic and nuclear isospin-non-conserving interactions. Calculations for the mirror energy differences in nuclei of the f 7/2 shell are described and compared with recent experimental data. These studies are extended to mirror nuclei in the upper sd and fp shells

  14. Constraining the Surface Energy Balance of Snow in Complex Terrain

    Science.gov (United States)

    Lapo, Karl E.

    Physically-based snow models form the basis of our understanding of current and future water and energy cycles, especially in mountainous terrain. These models are poorly constrained and widely diverge from each other, demonstrating a poor understanding of the surface energy balance. This research aims to improve our understanding of the surface energy balance in regions of complex terrain by improving our confidence in existing observations and improving our knowledge of remotely sensed irradiances (Chapter 1), critically analyzing the representation of boundary layer physics within land models (Chapter 2), and utilizing relatively novel observations to in the diagnoses of model performance (Chapter 3). This research has improved the understanding of the literal and metaphorical boundary between the atmosphere and land surface. Solar irradiances are difficult to observe in regions of complex terrain, as observations are subject to harsh conditions not found in other environments. Quality control methods were developed to handle these unique conditions. These quality control methods facilitated an analysis of estimated solar irradiances over mountainous environments. Errors in the estimated solar irradiance are caused by misrepresenting the effect of clouds over regions of topography and regularly exceed the range of observational uncertainty (up to 80Wm -2) in all regions examined. Uncertainty in the solar irradiance estimates were especially pronounced when averaging over high-elevation basins, with monthly differences between estimates up to 80Wm-2. These findings can inform the selection of a method for estimating the solar irradiance and suggest several avenues of future research for improving existing methods. Further research probed the relationship between the land surface and atmosphere as it pertains to the stable boundary layers that commonly form over snow-covered surfaces. Stable conditions are difficult to represent, especially for low wind speed

  15. Efficient Energy use in Different Applications

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, Lars

    2007-05-15

    There is a steadily growing awareness for environmental issues caused by the increased energy use, mainly in the industrial world. The use of fossil fuels has reached the point where it can not be looked at as an endless source. The resources are decreasing at a pace where alternative energy sources will be a necessity for this and future generations. Global warming, due to increased concentration of greenhouse gases in the atmosphere, has become one of the most important issues on the political agenda at all levels. A widespread opinion is that energy conservation technologies are needed and a shift towards renewable energy sources is required to attain a sustainable development of our society and a progress in the developing countries. This thesis is focusing on two different energy conservation technologies in different applications. The open absorption system, a modification of an absorption heat pump is a promising technique in moist air processes, recovering the latent heat in the air and decreasing the total heat demand. The technology has been tested in two full scale pilot plants at a sawmill operating four timber dryers and another unit installed at an indoor swimming pool. The technique has had positive outcomes in both operational and energy conservation respects. It has been shown that the energy demand was decreased considerably in both applications. The investment cost has proved to be relatively high, but optimization of operational parameters shows a potential to decrease the initial investment and make the technology more competitive. Pressurized entrained-flow high temperature black liquor gasification (PEHT-BLG), developed by Chemrec AB, is another novel technique presented in this thesis. Black liquor is an important by-product in the papermaking process. Chemicals and energy is recovered in the conventional recovery boiler where superheated steam is produced to generate electricity and process heat. The cooking chemicals are recovered from the

  16. Energy quantization for approximate H-surfaces and applications

    Directory of Open Access Journals (Sweden)

    Shenzhou Zheng

    2013-07-01

    Full Text Available We consider weakly convergent sequences of approximate H-surface maps defined in the plane with their tension fields bounded in $L^p$ for p> 4/3, and establish an energy quantization that accounts for the loss of their energies by the sum of energies over finitely many nontrivial bubbles maps on $mathbb{R}^2$. As a direct consequence, we establish the energy identity at finite singular time to their H-surface flows.

  17. Tuning surface porosity on vanadium surface by low energy He{sup +} ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, J.K., E-mail: jtripat@purdue.edu; Novakowski, T.J.; Hassanein, A.

    2016-08-15

    Highlights: • Surface nanostructuring on vanadium surface using novel He{sup +} ion irradiation process. • Tuning surface-porosity using high-flux, low-energy He{sup +} ion irradiation at constant elevated sample temperature (823–173 K). • Presented top-down approach guarantees good contact between different crystallites. • Sequential significant enhancement in surface-pore edge size (and corresponding reduction in surface-pore density) with increasing sample temperature. - Abstract: In the present study, we report on tuning the surface porosity on vanadium surfaces using high-flux, low-energy He{sup +} ion irradiation as function of sample temperature. Polished, mirror-finished vanadium samples were irradiated with 100 eV He{sup +} ions at a constant ion-flux of 7.2 × 10{sup 20} ions m{sup −2} s{sup −1} for 1 h duration at constant sample temperatures in the wide range of 823–1173 K. Our results show that the surface porosity of V{sub 2}O{sub 5} (naturally oxidized vanadium porous structure, after taking out from UHV) is strongly correlated to the sample temperature and is highly tunable. In fact, the surface porosity significantly increases with reducing sample temperature and reaches up to ∼87%. Optical reflectivity on these highly porous V{sub 2}O{sub 5} surfaces show ∼0% optical reflectivity at 670 nm wavelength, which is very similar to that of “black metal”. Combined with the naturally high melting point of V{sub 2}O{sub 5}, this very low optical reflectivity suggests potential application in solar power concentration technology. Additionally, this top-down approach guarantees relatively good contact between the different crystallites and avoids electrical conductivity limitations (if required). Since V{sub 2}O{sub 5} is naturally a potential photocatalytic material, the resulting sub-micron-sized cube-shaped porous structures could be used in solar water splitting for hydrogen production in energy applications.

  18. Measuring surface energy and evapotranspiration across Caribbean mangrove forests

    Science.gov (United States)

    Lagomasino, D.; Fatoyinbo, T. E.; Price, R.

    2014-12-01

    Coastal mangroves lose large amounts of water through evapotranspiration (ET) that can be equivalent to the amount of annual rainfall in certain years. Satellite remote sensing has been used to estimate surface energy and ET variability in many forested ecosystems, yet has been widely overlooked in mangrove forests. Using a combination of long-term datasets (30-year) acquired from the NASA Landsat 5 and 7 satellite databases, the present study investigated ET and surface energy balance variability between two mangrove forest sites in the Caribbean: 1) Everglades National Park (ENP; Florida, USA) and 2) Sian Ka'an Biosphere Reserve (SKBR; Quintana Roo, Mexico). A satellite-derived surface energy balance model was used to estimate ET in tall and scrub mangroves environments at ENP and SKBR. Results identified significant differences in soil heat flux measurements and ET between the tall and scrub mangrove environments. Scrub mangroves exhibited the highest soil heat flux coincident with the lowest biophysical indices (i.e., Fractional Vegetation Cover, Normalized Difference Vegetation Index, and Soil-Adjusted Vegetation Index) and ET rates. Mangrove damage and mortality was observed on the satellite images following strong tropical storms and associated with anthropogenic modifications and resulted in low values in spectral vegetation indices, higher soil heat flux, and higher ET. Recovery of the spectral characteristics, soil heat flux and ET was within 1-2 years following hurricane disturbance while, degradation caused by human disturbance persisted for many years. Remotely sensed ET of mangrove forests can provide estimates over a few decades and provide us with some understanding of how these environments respond to disturbances to the landscape in periods where no ground data exists or in locations that are difficult to access. Moreover, relationships between energy and water balance components developed for the coastal mangroves of Florida and Mexico could be

  19. The importance of surface finish to energy performance

    Directory of Open Access Journals (Sweden)

    Smith Geoff B.

    2017-01-01

    Full Text Available Power generation in solar energy systems, thermal control in buildings and mitigation of the Urban Heat Island problem, are all sensitive to directional response to incoming radiation. The radiation absorption and emission profile also plays a crucial role in each system's response and depends strongly on surface finish. This important sensitivity needs wider recognition in materials data sheets, system modeling, plus in materials and environmental engineering. The impact of surface roughness on thermal response of natural and man-made external environments is examined. Important examples will be given of the role of surface finish within each class. Total emittance links to the way surface finish influences directional emittance E(θ. Smooth surface thermal emittance on PV module covers, many solar absorbers, some roof paints, polished concrete, and glass windows can be up to 15% different from insulator results based on fully diffuse models of the same material. Widespread evidence indicates smooth metals and low-E solar absorber surfaces cool faster, and smooth insulators slower than previously thought. Matt paint is cooler than low sheen paint under the same solar heating impacts and normal concrete cooler than polished. Emittance for water is the prime environmental example of oblique impacts as it reflects strongly at oblique incidence, which leads to a significant drop in E(θ. Ripples or waves however raise water's average emittance. A surprise in this work was the high sensitivity of total E and its angular components to roughness in the depth range of 0.1–0.8 μm, which are well under ambient thermal IR wavelengths of 3–30 μm but common in metal finishing. Parallel energy flows such as evaporation and convective cooling vary if emittance varies. Thermal image analysis can provide insights into angular radiative effects.

  20. Surface energy effect on free vibration of nano-sized piezoelectric double-shell structures

    Science.gov (United States)

    Fang, Xue-Qian; Zhu, Chang-Song; Liu, Jin-Xi; Liu, Xiang-Lin

    2018-01-01

    Combining Goldenveizer-Novozhilov shell theory, thin plate theory and electro-elastic surface theory, the size-dependent vibration of nano-sized piezoelectric double-shell structures under simply supported boundary condition is presented, and the surface energy effect on the natural frequencies is discussed. The displacement components of the cylindrical nano-shells and annular nano-plates are expanded as the superposition of standard Fourier series based on Hamilton's principle. The total stresses with consideration of surface energy effect are derived, and the total energy function is obtained by using Rayleigh-Ritz energy method. The free vibration equation is solved, and the natural frequency is analyzed. In numerical examples, it is found that the surface elastic constant, piezoelectric constant and surface residual stress show different effects on the natural frequencies. The effect of surface piezoelectric constant is the maximum. The effect of dimensions of the double-shell under different surface material properties is also examined.

  1. Reflections on the surface energy imbalance problem

    Science.gov (United States)

    Ray Leuning; Eva van Gorsela; William J. Massman; Peter R. Isaac

    2012-01-01

    The 'energy imbalance problem' in micrometeorology arises because at most flux measurement sites the sum of eddy fluxes of sensible and latent heat (H + λE) is less than the available energy (A). Either eddy fluxes are underestimated or A is overestimated. Reasons for the imbalance are: (1) a failure to satisfy the fundamental assumption of one-...

  2. An energy conservation approach to adsorbate-induced surface stress and the extraction of binding energy using nanomechanics

    Science.gov (United States)

    Pinnaduwage, Lal A.; Boiadjiev, Vassil I.; Hawk, John E.; Gehl, Anthony C.; Fernando, Gayanath W.; Rohana Wijewardhana, L. C.

    2008-03-01

    Surface stress induced by molecular adsorption in three different binding processes has been studied experimentally using a microcantilever sensor. A comprehensive free-energy analysis based on an energy conservation approach is proposed to explain the experimental observations. We show that when guest molecules bind to atoms/molecules on a microcantilever surface, the released binding energy is retained in the host surface, leading to a metastable state where the excess energy on the surface is manifested as an increase in surface stress leading to the bending of the microcantilever. The released binding energy appears to be almost exclusively channeled to the surface energy, and energy distribution to other channels, including heat, appears to be inactive for this micromechanical system. When this excess surface energy is released, the microcantilever relaxes back to the original state, and the relaxation time depends on the particular binding process involved. Such vapor phase experiments were conducted for three binding processes: physisorption, hydrogen bonding, and chemisorption. Binding energies for these three processes were also estimated.

  3. An energy conservation approach to adsorbate-induced surface stress and the extraction of binding energy using nanomechanics

    Energy Technology Data Exchange (ETDEWEB)

    Pinnaduwage, Lal A; Boiadjiev, Vassil I; Hawk, John E; Gehl, Anthony C [Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831-6122 (United States); Fernando, Gayanath W [Physics Department, University of Connecticut, Storrs, CT 06269 (United States); Wijewardhana, L C Rohana [Physics Department, University of Cincinnati, Cincinnati, OH 45221 (United States)

    2008-03-12

    Surface stress induced by molecular adsorption in three different binding processes has been studied experimentally using a microcantilever sensor. A comprehensive free-energy analysis based on an energy conservation approach is proposed to explain the experimental observations. We show that when guest molecules bind to atoms/molecules on a microcantilever surface, the released binding energy is retained in the host surface, leading to a metastable state where the excess energy on the surface is manifested as an increase in surface stress leading to the bending of the microcantilever. The released binding energy appears to be almost exclusively channeled to the surface energy, and energy distribution to other channels, including heat, appears to be inactive for this micromechanical system. When this excess surface energy is released, the microcantilever relaxes back to the original state, and the relaxation time depends on the particular binding process involved. Such vapor phase experiments were conducted for three binding processes: physisorption, hydrogen bonding, and chemisorption. Binding energies for these three processes were also estimated.

  4. Kramers-Kronig transform for the surface energy loss function

    International Nuclear Information System (INIS)

    Tan, G.L.; DeNoyer, L.K.; French, R.H.; Guittet, M.J.; Gautier-Soyer, M.

    2005-01-01

    A new pair of Kramers-Kronig (KK) dispersion relationships for the transformation of surface energy loss function Im[-1/(ε + 1)] has been proposed. The validity of the new surface KK transform is confirmed, using both a Lorentz oscillator model and the surface energy loss functions determined from the experimental complex dielectric function of SrTiO 3 and tungsten metal. The interband transition strength spectra (J cv ) have been derived either directly from the original complex dielectric function or from the derived dielectric function obtained from the KK transform of the surface energy loss function. The original J cv trace and post-J cv trace overlapped together for the three modes, indicating that the new surface Kramers-Kronig dispersion relationship is valid for the surface energy loss function

  5. The Global Energy Balance Archive (GEBA) version 2017: a database for worldwide measured surface energy fluxes

    Science.gov (United States)

    Wild, Martin; Ohmura, Atsumu; Schär, Christoph; Müller, Guido; Folini, Doris; Schwarz, Matthias; Zyta Hakuba, Maria; Sanchez-Lorenzo, Arturo

    2017-08-01

    The Global Energy Balance Archive (GEBA) is a database for the central storage of the worldwide measured energy fluxes at the Earth's surface, maintained at ETH Zurich (Switzerland). This paper documents the status of the GEBA version 2017 dataset, presents the new web interface and user access, and reviews the scientific impact that GEBA data had in various applications. GEBA has continuously been expanded and updated and contains in its 2017 version around 500 000 monthly mean entries of various surface energy balance components measured at 2500 locations. The database contains observations from 15 surface energy flux components, with the most widely measured quantity available in GEBA being the shortwave radiation incident at the Earth's surface (global radiation). Many of the historic records extend over several decades. GEBA contains monthly data from a variety of sources, namely from the World Radiation Data Centre (WRDC) in St. Petersburg, from national weather services, from different research networks (BSRN, ARM, SURFRAD), from peer-reviewed publications, project and data reports, and from personal communications. Quality checks are applied to test for gross errors in the dataset. GEBA has played a key role in various research applications, such as in the quantification of the global energy balance, in the discussion of the anomalous atmospheric shortwave absorption, and in the detection of multi-decadal variations in global radiation, known as global dimming and brightening. GEBA is further extensively used for the evaluation of climate models and satellite-derived surface flux products. On a more applied level, GEBA provides the basis for engineering applications in the context of solar power generation, water management, agricultural production and tourism. GEBA is publicly accessible through the internet via http://www.geba.ethz.ch. Supplementary data are available at https://doi.org/10.1594/PANGAEA.873078.

  6. Model calculation for energy loss in ion-surface collisions

    International Nuclear Information System (INIS)

    Miraglia, J.E.; Gravielle, M.S.

    2003-01-01

    The so-called local plasma approximation is generalized to deal with projectiles colliding with surfaces of amorphous solids and with a specific crystalline structure (plannar channeling). Energy loss of protons grazingly colliding with aluminum, SnTe alloy, and LiF surfaces is investigated. The calculations agree quite well with previous theoretical results and explain the experimental findings of energy loss for aluminum and SnTe alloy, but they fall short to explain the data for LiF surfaces

  7. Theoretical studies of potential energy surfaces and computational methods

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, R. [Argonne National Laboratory, IL (United States)

    1993-12-01

    This project involves the development, implementation, and application of theoretical methods for the calculation and characterization of potential energy surfaces involving molecular species that occur in hydrocarbon combustion. These potential energy surfaces require an accurate and balanced treatment of reactants, intermediates, and products. This difficult challenge is met with general multiconfiguration self-consistent-field (MCSCF) and multireference single- and double-excitation configuration interaction (MRSDCI) methods. In contrast to the more common single-reference electronic structure methods, this approach is capable of describing accurately molecular systems that are highly distorted away from their equilibrium geometries, including reactant, fragment, and transition-state geometries, and of describing regions of the potential surface that are associated with electronic wave functions of widely varying nature. The MCSCF reference wave functions are designed to be sufficiently flexible to describe qualitatively the changes in the electronic structure over the broad range of geometries of interest. The necessary mixing of ionic, covalent, and Rydberg contributions, along with the appropriate treatment of the different electron-spin components (e.g. closed shell, high-spin open-shell, low-spin open shell, radical, diradical, etc.) of the wave functions, are treated correctly at this level. Further treatment of electron correlation effects is included using large scale multireference CI wave functions, particularly including the single and double excitations relative to the MCSCF reference space. This leads to the most flexible and accurate large-scale MRSDCI wave functions that have been used to date in global PES studies.

  8. Critical assessment of Pt surface energy - An atomistic study

    Science.gov (United States)

    Kim, Jin-Soo; Seol, Donghyuk; Lee, Byeong-Joo

    2018-04-01

    Despite the fact that surface energy is a fundamental quantity in understanding surface structure of nanoparticle, the results of experimental measurements and theoretical calculations for the surface energy of pure Pt show a wide range of scattering. It is necessary to further ensure the surface energy of Pt to find the equilibrium shape and atomic configuration in Pt bimetallic nanoparticles accurately. In this article, we critically assess and optimize the Pt surface energy using a semi-empirical atomistic approach based on the second nearest-neighbor modified embedded-atom method interatomic potential. That is, the interatomic potential of pure Pt was adjusted in a way that the surface segregation tendency in a wide range of Pt binary alloys is reproduced in accordance with experimental information. The final optimized Pt surface energy (mJ/m2) is 2036 for (100) surface, 2106 for (110) surface, and 1502 for (111) surface. The potential can be utilized to find the equilibrium shape and atomic configuration of Pt bimetallic nanoparticles more accurately.

  9. Improving Energy Efficiency In Thermal Oil Recovery Surface Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Murthy Nadella, Narayana

    2010-09-15

    Thermal oil recovery methods such as Cyclic Steam Stimulation (CSS), Steam Assisted Gravity Drainage (SAGD) and In-situ Combustion are being used for recovering heavy oil and bitumen. These processes expend energy to recover oil. The process design of the surface facilities requires optimization to improve the efficiency of oil recovery by minimizing the energy consumption per barrel of oil produced. Optimization involves minimizing external energy use by heat integration. This paper discusses the unit processes and design methodology considering thermodynamic energy requirements and heat integration methods to improve energy efficiency in the surface facilities. A design case study is presented.

  10. Valence bond model potential energy surface for H4

    International Nuclear Information System (INIS)

    Silver, D.M.; Brown, N.J.

    1980-01-01

    Potential energy surfaces for the H 4 system are derived using the valence bond procedure. An ab initio evaluation of the valence bond energy expression is described and some of its numerical properties are given. Next, four semiempirical evaluations of the valence bond energy are defined and parametrized to yield reasonable agreement with various ab initio calculations of H 4 energies. Characteristics of these four H 4 surfaces are described by means of tabulated energy minima and equipotential contour maps for selected geometrical arrangements of the four nuclei

  11. New Material Development for Surface Layer and Surface Technology in Tribology Science to Improve Energy Efficiency

    International Nuclear Information System (INIS)

    Ismail, R.; Tauviqirrahman, M.; Jamari; Schipper, D. J.

    2009-01-01

    This paper reviews the development of new material and surface technology in tribology and its contribution to energy efficiency. Two examples of the economic benefits, resulted from the optimum tribology in the transportation sector and the manufacturing industry are discussed. The new materials are proposed to modify the surface property by laminating the bulk material with thin layer/coating. Under a suitable condition, the thin layer on a surface can provide a combination of good wear, a low friction and corrosion resistance for the mechanical components. The innovation in layer technology results molybdenum disulfide (MoS2), diamond like carbon (DLC), cubic boron nitride (CBN) and diamond which perform satisfactory outcome. The application of the metallic coatings to carbon fibre reinforced polymer matrix composites (CFRP) has the capacity to provide considerable weight and power savings for many engineering components. The green material for lubricant and additives such as the use of sunflower oil which possesses good oxidation resistance and the use of mallee leaves as bio‐degradable solvent are used to answer the demand of the environmentally friendly material with good performance. The tribology research implementation for energy efficiency also touches the simple things around us such as: erasing the laser‐print in a paper with different abrasion techniques. For the technology in the engineering surface, the consideration for generating the suitable surface of the components in running‐in period has been discussed in order to prolong the components life and reduce the machine downtime. The conclusion, tribology can result in reducing manufacturing time, reducing the maintenance requirements, prolonging the service interval, improving durability, reliability and mechanical components life, and reducing harmful exhaust emission and waste. All of these advantages will increase the energy efficiency and the economic benefits.

  12. New Material Development for Surface Layer and Surface Technology in Tribology Science to Improve Energy Efficiency

    Science.gov (United States)

    Ismail, R.; Tauviqirrahman, M.; Jamari, Jamari; Schipper, D. J.

    2009-09-01

    This paper reviews the development of new material and surface technology in tribology and its contribution to energy efficiency. Two examples of the economic benefits, resulted from the optimum tribology in the transportation sector and the manufacturing industry are discussed. The new materials are proposed to modify the surface property by laminating the bulk material with thin layer/coating. Under a suitable condition, the thin layer on a surface can provide a combination of good wear, a low friction and corrosion resistance for the mechanical components. The innovation in layer technology results molybdenum disulfide (MoS2), diamond like carbon (DLC), cubic boron nitride (CBN) and diamond which perform satisfactory outcome. The application of the metallic coatings to carbon fibre reinforced polymer matrix composites (CFRP) has the capacity to provide considerable weight and power savings for many engineering components. The green material for lubricant and additives such as the use of sunflower oil which possesses good oxidation resistance and the use of mallee leaves as bio-degradable solvent are used to answer the demand of the environmentally friendly material with good performance. The tribology research implementation for energy efficiency also touches the simple things around us such as: erasing the laser-print in a paper with different abrasion techniques. For the technology in the engineering surface, the consideration for generating the suitable surface of the components in running-in period has been discussed in order to prolong the components life and reduce the machine downtime. The conclusion, tribology can result in reducing manufacturing time, reducing the maintenance requirements, prolonging the service interval, improving durability, reliability and mechanical components life, and reducing harmful exhaust emission and waste. All of these advantages will increase the energy efficiency and the economic benefits.

  13. Interaction of the human body and surfaces of different stiffness during drop jumps.

    Science.gov (United States)

    Arampatzis, Adamantios; Stafilidis, Savvas; Morey-Klapsing, Gaspar; Brüggemann, Gert-peter

    2004-03-01

    The purpose of this study was to examine two hypotheses: (a) the stiffness of the surface influences the leg stiffness of the subjects during drop jumps, and (b) drop jumping performance (jumping height and energy rates of the subject's center of mass during the contact phase) increases when decreasing surface stiffness due to a greater energy storage capacity of the surface for a given acting force. Ten female subjects performed a series of drop jumps from 40-cm height onto two sprung surfaces with different stiffness. Those trials of each subject displaying the maximal mechanical power during the upward phase were analyzed. The ground reaction forces were measured using a force plate. Sagittal kinematics of the subject's body positions and the deformation of the surface were recorded using two high-speed video cameras. On the soft surface, the jumping height and the energy rates of the subjects during the contact phase were greater than on the hard one. The energy delivered by the subjects during the upward phase, the leg and joint stiffness, as well as the range of motion of the subjects remained unchanged for both surfaces. The absolute energy loss is lower for the hard surface, but the jumping performance is greater for the soft one. The reason is a higher ratio of positive to negative mechanical work done by the subjects during the contact phase. The adjustment of the subjects to different surfaces is not only dependent on the stiffness of the surface but also on the intensity of the movement.

  14. Delta self-consistent field method to obtain potential energy surfaces of excited molecules on surfaces

    DEFF Research Database (Denmark)

    Gavnholt, Jeppe; Olsen, Thomas; Engelund, Mads

    2008-01-01

    is a density-functional method closely resembling standard density-functional theory (DFT), the only difference being that in Delta SCF one or more electrons are placed in higher lying Kohn-Sham orbitals instead of placing all electrons in the lowest possible orbitals as one does when calculating the ground......-state energy within standard DFT. We extend the Delta SCF method by allowing excited electrons to occupy orbitals which are linear combinations of Kohn-Sham orbitals. With this extra freedom it is possible to place charge locally on adsorbed molecules in the calculations, such that resonance energies can...... be estimated, which is not possible in traditional Delta SCF because of very delocalized Kohn-Sham orbitals. The method is applied to N2, CO, and NO adsorbed on different metallic surfaces and compared to ordinary Delta SCF without our modification, spatially constrained DFT, and inverse...

  15. Atomic force microscopy analysis of different surface treatments of Ti dental implant surfaces

    International Nuclear Information System (INIS)

    Bathomarco, R.V.; Solorzano, G.; Elias, C.N.; Prioli, R.

    2004-01-01

    The surface of commercial unalloyed titanium, used in dental implants, was analyzed by atomic force microscopy. The morphology, roughness, and surface area of the samples, submitted to mechanically-induced erosion, chemical etching and a combination of both, were compared. The results show that surface treatments strongly influence the dental implant physical and chemical properties. An analysis of the length dependence of the implant surface roughness shows that, for scan sizes larger than 50 μm, the average surface roughness is independent of the scanning length and that the surface treatments lead to average surface roughness in the range of 0.37 up to 0.48 μm. It is shown that the implant surface energy is sensitive to the titanium surface area. As the area increases there is a decrease in the surface contact angle

  16. Atomic force microscopy analysis of different surface treatments of Ti dental implant surfaces

    Science.gov (United States)

    Bathomarco, Ti R. V.; Solorzano, G.; Elias, C. N.; Prioli, R.

    2004-06-01

    The surface of commercial unalloyed titanium, used in dental implants, was analyzed by atomic force microscopy. The morphology, roughness, and surface area of the samples, submitted to mechanically-induced erosion, chemical etching and a combination of both, were compared. The results show that surface treatments strongly influence the dental implant physical and chemical properties. An analysis of the length dependence of the implant surface roughness shows that, for scan sizes larger than 50 μm, the average surface roughness is independent of the scanning length and that the surface treatments lead to average surface roughness in the range of 0.37 up to 0.48 μm. It is shown that the implant surface energy is sensitive to the titanium surface area. As the area increases there is a decrease in the surface contact angle.

  17. Probing Free-Energy Surfaces with Differential Scanning Calorimetry

    Science.gov (United States)

    Sanchez-Ruiz, Jose M.

    2011-05-01

    Many aspects of protein folding can be understood in terms of projections of the highly dimensional energy landscape onto a few (or even only one) particularly relevant coordinates. These free-energy surfaces can be probed conveniently from experimental differential scanning calorimetry (DSC) thermograms, as DSC provides a direct relation with the protein partition function. Free-energy surfaces thus obtained are consistent with two fundamental scenarios predicted by the energy-landscape perspective: (a) well-defined macrostates separated by significant free-energy barriers, in some cases, and, in many other cases, (b) marginal or even vanishingly small barriers, which furthermore show a good correlation with kinetics for fast- and ultrafast-folding proteins. Overall, the potential of DSC to assess free-energy surfaces for a wide variety of proteins makes it possible to address fundamental issues, such as the molecular basis of the barrier modulations produced by natural selection in response to functional requirements or to ensure kinetic stability.

  18. Is atomic energy different from a nucleus?

    International Nuclear Information System (INIS)

    Lee, Sun Young

    1995-07-01

    This book describes of two faces of nuclear energy : the secret of a nuclear, the history of nuclear energy : the scientists with a nuclear, the nuclear energy generation : the third disapprobation, a nuclear weapon : Choice of fear, the Korean peninsula and a nuclear and nuclear energy and utilization in peace. It consists of 31 questions and the answers of the questions about nuclear energy and nucleus.

  19. Cohesion and coordination effects on transition metal surface energies

    Science.gov (United States)

    Ruvireta, Judit; Vega, Lorena; Viñes, Francesc

    2017-10-01

    Here we explore the accuracy of Stefan equation and broken-bond model semiempirical approaches to obtain surface energies on transition metals. Cohesive factors are accounted for either via the vaporization enthalpies, as proposed in Stefan equation, or via cohesive energies, as employed in the broken-bond model. Coordination effects are considered including the saturation degree, as suggested in Stefan equation, employing Coordination Numbers (CN), or as the ratio of broken bonds, according to the bond-cutting model, considering as well the square root dependency of the bond strength on CN. Further, generalized coordination numbers CN bar are contemplated as well, exploring a total number of 12 semiempirical formulations on the three most densely packed surfaces of 3d, 4d, and 5d Transition Metals (TMs) displaying face-centered cubic (fcc), body-centered cubic (bcc), or hexagonal close-packed (hcp) crystallographic structures. Estimates are compared to available experimental surface energies obtained extrapolated to zero temperature. Results reveal that Stefan formula cohesive and coordination dependencies are only qualitative suited, but unadvised for quantitative discussion, as surface energies are highly overestimated, favoring in addition the stability of under-coordinated surfaces. Broken-bond cohesion and coordination dependencies are a suited basis for quantitative comparison, where square-root dependencies on CN to account for bond weakening are sensibly worse. An analysis using Wulff shaped averaged surface energies suggests the employment of broken-bond model using CN to gain surface energies for TMs, likely applicable to other metals.

  20. Direct Measurement of the Surface Energy of Graphene.

    Science.gov (United States)

    van Engers, Christian D; Cousens, Nico E A; Babenko, Vitaliy; Britton, Jude; Zappone, Bruno; Grobert, Nicole; Perkin, Susan

    2017-06-14

    Graphene produced by chemical vapor deposition (CVD) is a promising candidate for implementing graphene in a range of technologies. In most device configurations, one side of the graphene is supported by a solid substrate, wheras the other side is in contact with a medium of interest, such as a liquid or other two-dimensional material within a van der Waals stack. In such devices, graphene interacts on both faces via noncovalent interactions and therefore surface energies are key parameters for device fabrication and operation. In this work, we directly measured adhesive forces and surface energies of CVD-grown graphene in dry nitrogen, water, and sodium cholate using a modified surface force balance. For this, we fabricated large (∼1 cm 2 ) and clean graphene-coated surfaces with smooth topography at both macro- and nanoscales. By bringing two such surfaces into contact and measuring the force required to separate them, we measured the surface energy of single-layer graphene in dry nitrogen to be 115 ± 4 mJ/m 2 , which was similar to that of few-layer graphene (119 ± 3 mJ/m 2 ). In water and sodium cholate, we measured interfacial energies of 83 ± 7 and 29 ± 6 mJ/m 2 , respectively. Our work provides the first direct measurement of graphene surface energy and is expected to have an impact both on the development of graphene-based devices and contribute to the fundamental understanding of surface interactions.

  1. A Surface Temperature Initiated Closure (STIC) for surface energy balance fluxes

    DEFF Research Database (Denmark)

    Mallick, Kaniska; Jarvis, Andrew J.; Boegh, Eva

    2014-01-01

    The use of Penman–Monteith (PM) equation in thermal remote sensing based surface energy balance modeling is not prevalent due to the unavailability of any direct method to integrate thermal data into the PM equation and due to the lack of physical models expressing the surface (or stomatal......) and boundary layer conductances (gS and gB) as a function of surface temperature. Here we demonstrate a new method that physically integrates the radiometric surface temperature (TS) into the PM equation for estimating the terrestrial surface energy balance fluxes (sensible heat, H and latent heat, λ......E). The method combines satellite TS data with standard energy balance closure models in order to derive a hybrid closure that does not require the specification of surface to atmosphere conductance terms. We call this the Surface Temperature Initiated Closure (STIC), which is formed by the simultaneous solution...

  2. Surface energy and work function of elemental metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Rosengaard, N. M.

    1992-01-01

    and noble metals, as derived from the surface tension of liquid metals. In addition, they give work functions which agree with the limited experimental data obtained from single crystals to within 15%, and explain the smooth behavior of the experimental work functions of polycrystalline samples......We have performed an ab initio study of the surface energy and the work function for six close-packed surfaces of 40 elemental metals by means of a Green’s-function technique, based on the linear-muffin-tin-orbitals method within the tight-binding and atomic-sphere approximations. The results...... are in excellent agreement with a recent full-potential, all-electron, slab-supercell calculation of surface energies and work functions for the 4d metals. The present calculations explain the trend exhibited by the surface energies of the alkali, alkaline earth, divalent rare-earth, 3d, 4d, and 5d transition...

  3. Energy exchange in thermal energy atom-surface scattering: impulsive models

    International Nuclear Information System (INIS)

    Barker, J.A.; Auerbach, D.J.

    1979-01-01

    Energy exchange in thermal energy atom surface collisions is studied using impulsive ('hard cube' and 'hard sphere') models. Both models reproduce the observed nearly linear relation between outgoing and incoming energies. In addition, the hard-sphere model accounts for the widths of the outcoming energy distributions. (Auth.)

  4. Phytoremediation of differents wastewaters using energy crops

    OpenAIRE

    Leigue Fernandez, Maria Alejandra

    2014-01-01

    The sources of renewable energy acquire considerable interest, if accompanied by a more rational use of energy, to facilitate the transaction by a high use of fossil fuels to a sustainable use of renewable energy. There are many alternative energy source such as wind, solar, geothermal and biomass that fulfil the criteria of sustainability and economic feasibility. Biomass refers to all the vegetable matter that can be obtained from photosynthesis. Biodiesel can be produced from a variety of ...

  5. Effect of crystal habits on the surface energy and cohesion of crystalline powders.

    Science.gov (United States)

    Shah, Umang V; Olusanmi, Dolapo; Narang, Ajit S; Hussain, Munir A; Gamble, John F; Tobyn, Michael J; Heng, Jerry Y Y

    2014-09-10

    The role of surface properties, influenced by particle processing, in particle-particle interactions (powder cohesion) is investigated in this study. Wetting behaviour of mefenamic acid was found to be anisotropic by sessile drop contact angle measurements on macroscopic (>1cm) single crystals, with variations in contact angle of water from 56.3° to 92.0°. This is attributed to variations in surface chemical functionality at specific facets, and confirmed using X-ray photoelectron spectroscopy (XPS). Using a finite dilution inverse gas chromatography (FD-IGC) approach, the surface energy heterogeneity of powders was determined. The surface energy profile of different mefenamic acid crystal habits was directly related to the relative exposure of different crystal facets. Cohesion, determined by a uniaxial compression test, was also found to relate to surface energy of the powders. By employing a surface modification (silanisation) approach, the contribution from crystal shape from surface area and surface energy was decoupled. By "normalising" contribution from surface energy and surface area, needle shaped crystals were found to be ∼2.5× more cohesive compared to elongated plates or hexagonal cuboid shapes crystals. Copyright © 2014. Published by Elsevier B.V.

  6. Low-energy particle treatment of GaAs surface

    International Nuclear Information System (INIS)

    Pincik, E.; Ivanco, J.; Brunner, R.; Jergel, M.; Falcony, C.; Ortega, L.; Kucera, J. M.

    2002-01-01

    The paper presents results of a complex study of surface properties of high-doped (2x10 18 cm -3 ) and semi-insulating GaAs after an interaction with the particles coming from low-energy ion sources such as RF plasma and ion beams. The virgin samples were mechano-chemically polished liquid-encapsulated Czochralski-grown GaAs (100) oriented wafers. The crystals were mounted on the grounded electrode (holder). The mixture Ar+H 2 as well as O 2 and CF 4 were used as working gases: In addition, a combination of two different in-situ exposures was applied, such as e.g. hydrogen and oxygen. Structural, electrical and optical properties of the exposed surfaces were investigated using X-ray diffraction at grazing incidence, quasi-static and high-frequency C-V curve measurements, deep-level transient spectroscopy, photo-reflectance, and photoluminescence. Plasma and ion beam exposures were performed in a commercial RF capacitively coupled plasma equipment SECON XPL-200P and a commercial LPAI device, respectively. The evolution of surface properties as a function of the pressure of working gas and the duration of exposure was observed. (Authors)

  7. Surface studies with high-energy ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Stensgaard, Ivan [Aarhus Univ. (Denmark). Inst. of Physics

    1992-07-01

    High-energy ion scattering is an extremely useful technique for surface studies. Three methods for surface composition analysis (Rutherford backscattering, nuclear-reaction analysis and elastic recoil detection) are discussed. Directional effects in ion-beam surface interactions (shadowing and blocking) form the basis for surface structure analysis with high-energy ion beams and these phenomena are addressed in some detail. It is shown how surface relaxation and reconstruction, as well as positions of adsorbed atoms, can be determined by comparison with computer simulations. A special technique called transmission channelling is introduced and shown to be particularly well suited for studies of adsorption positions, even of hydrogen. Recent developments in the field are demonstrated by discussing a large number of important (experimental) applications which also include surface dynamics and melting, as well as epitaxy and interface structure. (author).

  8. On analogy between surface fracture energy and activaiton energy of bonding in solid phase

    International Nuclear Information System (INIS)

    Shatinsky, V.F.; Kopylov, V.I.

    1976-01-01

    This article makes an attempt on the basis of experimental data to compare the processes of failure and formation of a bond by comparing the energy consumptions going in one case or another into initial plastic deformation of a certain volume and the further interatomic interaction at the boundary (separation, formation of the bond). Two values characterizing the different processes - the unit failure energy γ and the activation energy for the formation of a bond Q - are compared. It has been established that the energy consumed for plastic deformation and adhesion interaction of atoms on the surface of microprojections and providing the formation of a bond in the solid-phase condition is close to the specific failure energy. The equality of energies consumed for the formation of a bond and failure allows to make use of any of those characteristics to calculate parameters of processes of the formation of a bond and failure. It seems to be convenient in the analysis of the failure process at a temperature when the ductility is high and methodically, the crack propagation is hard to investigate, in particular to estimate the volume of the preliminary failure zone. Having determined γ from the contact interaction data, the strength characteristics can be evaluated. (author)

  9. Ultralow energy ion beam surface modification of low density polyethylene.

    Science.gov (United States)

    Shenton, Martyn J; Bradley, James W; van den Berg, Jaap A; Armour, David G; Stevens, Gary C

    2005-12-01

    Ultralow energy Ar+ and O+ ion beam irradiation of low density polyethylene has been carried out under controlled dose and monoenergetic conditions. XPS of Ar+-treated surfaces exposed to ambient atmosphere show that the bombardment of 50 eV Ar+ ions at a total dose of 10(16) cm(-2) gives rise to very reactive surfaces with oxygen incorporation at about 50% of the species present in the upper surface layer. Using pure O+ beam irradiation, comparatively low O incorporation is achieved without exposure to atmosphere (approximately 13% O in the upper surface). However, if the surface is activated by Ar+ pretreatment, then large oxygen contents can be achieved under subsequent O+ irradiation (up to 48% O). The results show that for very low energy (20 eV) oxygen ions there is a dose threshold of about 5 x 10(15) cm(-2) before surface oxygen incorporation is observed. It appears that, for both Ar+ and O+ ions in this regime, the degree of surface modification is only very weakly dependent on the ion energy. The results suggest that in the nonequilibrium plasma treatment of polymers, where the ion flux is typically 10(18) m(-2) s(-1), low energy ions (<50 eV) may be responsible for surface chemical modification.

  10. Low energy quasi free scattering on nuclear surface

    Energy Technology Data Exchange (ETDEWEB)

    Shiyuan, S.

    1983-05-01

    The result of RGM calculation of low energy /sup 3/He(n, n)/sup 3/ He total elastic cross section does not agree well with experimental data for E/sub n/<1 MeV. This discrepancy can be improved by assuming lwo energy quasi-free scattering of particles beyond the nuclear surface.

  11. Soil heat flux and day time surface energy balance closure

    Indian Academy of Sciences (India)

    Soil heat flux; surface energy balance; Bowen's ratio; sensible and latent ... The energy storage term for the soil layer 0–0.05 m is calculated and the ground heat ... When a new method that accounts for both soil thermal conduction and soil ...

  12. Observations of discrete energy loss effects in spectra of positrons reflected from solid surfaces

    International Nuclear Information System (INIS)

    Dale, J.M.; Hulett, L.D.; Pendyala, S.

    1980-01-01

    Surfaces of tungsten and silicon have been bombarded with monoenergetic beams of positrons and electrons. Spectra of reflected particles show energy loss tails with discrete peaks at kinetic energies about 15 eV lower than that of the elastic peaks. In the higher energy loss range for tungsten, positron spectra show fine structure that is not apparent in the electron spectra. This suggests that the positrons are losing energy through mechanisms different from that of the electrons

  13. Atom-surface interaction: Zero-point energy formalism

    International Nuclear Information System (INIS)

    Paranjape, V.V.

    1985-01-01

    The interaction energy between an atom and a surface formed by a polar medium is derived with use of a new approach based on the zero-point energy formalism. It is shown that the energy depends on the separation Z between the atom and the surface. With increasing Z, the energy decreases according to 1/Z 3 , while with decreasing Z the energy saturates to a finite value. It is also shown that the energy is affected by the velocity of the atom, but this correction is small. Our result for large Z is consistent with the work of Manson and Ritchie [Phys. Rev. B 29, 1084 (1984)], who follow a more traditional approach to the problem

  14. Polar surface energies of iono-covalent materials: implications of a charge-transfer model tested on Li2FeSiO4 surfaces.

    Science.gov (United States)

    Hörmann, Nicolas G; Groß, Axel

    2014-07-21

    The ionic compounds that are used as electrode materials in Li-based rechargeable batteries can exhibit polar surfaces that in general have high surface energies. We derive an analytical estimate for the surface energy of such polar surfaces assuming charge redistribution as a polarity compensating mechanism. The polar contribution to the converged surface energy is found to be proportional to the bandgap multiplied by the surface charge necessary to compensate for the depolarization field, and some higher order correction terms that depend on the specific surface. Other features, such as convergence behavior, coincide with published results. General conclusions are drawn on how to perform polar surface energy calculations in a slab configuration and upper boundaries of "purely" polar surface energies are estimated. Furthermore, we compare these findings with results obtained in a density functional theory study of Li(2)FeSiO(4) surfaces. We show that typical polar features are observed and provide a decomposition of surface energies into polar and local bond-cutting contributions for 29 different surfaces. We show that the model is able to explain subtle differences of GGA and GGA+U surface energy calculations. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Potential energy surfaces for nucleon exchanging in dinuclear systems

    International Nuclear Information System (INIS)

    Li Jianfeng; Xu Hushan; Li Wenfei; Zuo Wei; Li Junqing; Wang Nan; Zhao Enguang

    2003-01-01

    The experimental measurements have provided the evidence that the suppression of fusion cross-section caused by quasi-fission is very important for the synthesis of super-heavy nuclei by heavy ion collisions. The potential energy surface due to the nucleon transfer in the collision process is the driven potential, which governs the nucleon transfer, so that governs the competition between the fusion and quasi-fission. The dinuclear system potential energy surface also gives the information about the optimum projectile-target combination, as well as the optimum excitation energy for the synthesis of super-heavy nuclei by heavy ion collisions

  16. Improvement of Polytetrafluoroethylene Surface Energy by Repetitive Pulse Non-Thermal Plasma Treatment in Atmospheric Air

    International Nuclear Information System (INIS)

    Yang Guoqing; Zhang Guanjun; Zhang Wenyuan

    2011-01-01

    Improvement of polytetrafluoroethylene surface energy by non-thermal plasma treatment is presented, using a nanosecond-positive-edge repetitive pulsed dielectric barrier discharge generator in atmospheric air. The electrical parameters including discharging power, peak and density of micro-discharge current were calculated, and the electron energy was estimated. Surface treatment experiments of polytetrafluoroethylene films were conducted for both different applied voltages and different treating durations. Results show that the surface energy of polytetrafluoroethylene film could be improved to 40 mJ/m 2 or more by plasma treatment. Surface roughness measurement and surface X-ray photoelectron spectroscopy analysis indicate that there are chemical etching and implantation of polar oxygen groups in the sample surface treating process, resulting in the improvement of the sample surface energy. Compared with an AC source of 50 Hz, the dielectric barrier discharges generated by a repetitive pulsed source could provide higher peak power, lower mean power, larger micro-discharge current density and higher electron energy. Therefore, with the same applied peak voltage and treating duration, the improvement of polytetrafluoroethylene surface energy using repetitive pulsed plasma is more effective, and the plasma treatment process based on repetitive pulsed dielectric barrier discharges in air is thus feasible and applicable.

  17. Vibrational Surface Electron-Energy-Loss Spectroscopy Probes Confined Surface-Phonon Modes

    Directory of Open Access Journals (Sweden)

    Hugo Lourenço-Martins

    2017-12-01

    Full Text Available Recently, two reports [Krivanek et al. Nature (London 514, 209 (2014NATUAS0028-083610.1038/nature13870, Lagos et al. Nature (London 543, 529 (2017NATUAS0028-083610.1038/nature21699] have demonstrated the amazing possibility to probe vibrational excitations from nanoparticles with a spatial resolution much smaller than the corresponding free-space phonon wavelength using electron-energy-loss spectroscopy (EELS. While Lagos et al. evidenced a strong spatial and spectral modulation of the EELS signal over a nanoparticle, Krivanek et al. did not. Here, we show that discrepancies among different EELS experiments as well as their relation to optical near- and far-field optical experiments [Dai et al. Science 343, 1125 (2014SCIEAS0036-807510.1126/science.1246833] can be understood by introducing the concept of confined bright and dark surface phonon modes, whose density of states is probed by EELS. Such a concise formalism is the vibrational counterpart of the broadly used formalism for localized surface plasmons [Ouyang and Isaacson Philos. Mag. B 60, 481 (1989PMABDJ1364-281210.1080/13642818908205921, García de Abajo and Aizpurua Phys. Rev. B 56, 15873 (1997PRBMDO0163-182910.1103/PhysRevB.56.15873, García de Abajo and Kociak Phys. Rev. Lett. 100, 106804 (2008PRLTAO0031-900710.1103/PhysRevLett.100.106804, Boudarham and Kociak Phys. Rev. B 85, 245447 (2012PRBMDO1098-012110.1103/PhysRevB.85.245447]; it makes it straightforward to predict or interpret phenomena already known for localized surface plasmons such as environment-related energy shifts or the possibility of 3D mapping of the related surface charge densities [Collins et al. ACS Photonics 2, 1628 (2015APCHD52330-402210.1021/acsphotonics.5b00421].

  18. Elastic layer under axisymmetric indentation and surface energy effects

    Science.gov (United States)

    Intarit, Pong-in; Senjuntichai, Teerapong; Rungamornrat, Jaroon

    2018-04-01

    In this paper, a continuum-based approach is adopted to investigate the contact problem of an elastic layer with finite thickness and rigid base subjected to axisymmetric indentation with the consideration of surface energy effects. A complete Gurtin-Murdoch surface elasticity is employed to consider the influence of surface stresses. The indentation problem of a rigid frictionless punch with arbitrary axisymmetric profiles is formulated by employing the displacement Green's functions, derived with the aid of Hankel integral transform technique. The problem is solved by assuming the contact pressure distribution in terms of a linear combination of admissible functions and undetermined coefficients. Those coefficients are then obtained by employing a collocation technique and an efficient numerical quadrature scheme. The accuracy of proposed solution technique is verified by comparing with existing solutions for rigid indentation on an elastic half-space. Selected numerical results for the indenters with flat-ended cylindrical and paraboloidal punch profiles are presented to portray the influence of surface energy effects on elastic fields of the finite layer. It is found that the presence of surface stresses renders the layer stiffer, and the size-dependent behavior of elastic fields is observed in the present solutions. In addition, the surface energy effects become more pronounced with smaller contact area; thus, the influence of surface energy cannot be ignored in the analysis of indentation problem especially when the indenter size is very small such as in the case of nanoindentation.

  19. Colloquium on the risks of different energy sources

    International Nuclear Information System (INIS)

    1980-01-01

    Four subjects, each taking up one session, were dealt with in this Colloquium. The first is the definition of the health risk concept which is only obvious on the surface. It was shown how within the medical world itself, apparently the most competent to discover and evaluate these risks, this definition is still approximate both in theory and in practice. The second theme dealt with concerns the way in which risks are viewed by the general public. By a psychological and sociological approach it is possible to form an idea of how differently opinion reacts to risks of similar gravity and probability. The apprehension of risks and the opposition to nuclear energy were analysed in detail in this session. The third subject, more analytical and probably one of the most topical is concerned with the inventory of risks due to each industrial energy sector. This session was in two parts, the first devoted to problems specific to each source of energy including nuclear, the second to common problems (pollution of air, fresh water and sea water, and long-term effects (nuclear wastes for example). The fourth and last session dealt with a fundamental problem, methods of studying these risks. The conclusions of different enquiries are always very similar: the energy source hierarchy, in order of diminishing risks, is as follows: coal, liquid hydrocarbons, nuclear and gaseous hydrocarbons [fr

  20. Couple of biomimetic surfaces with different morphologies for remanufacturing nonuniform wear rail surface

    Science.gov (United States)

    Sui, Qi; Zhou, Hong; Yang, Lin; Zhang, Haifeng; Feng, Li; Zhang, Peng

    2018-02-01

    In this work, biomimetic laser treatment was performed on repairing and remanufacturing the nonuniform worn rail surface. The wearing depth distribution of three work regions of a failure rail surface was discussed, and different thickness hardening layers with different microstructure, microhardness and wear resistances were detected from the worm surfaces. Varying wear resistances of the surfaces with different biomimetic morphologies were obtained by biomimetic laser treatments, and the corresponding effect on the lubrication sliding wear of treated and untreated surfaces were studied for comparative study. In addition, the relationship between wear resistance and the spacing of units was also provided, which can lay the important theoretical foundation for avoiding the wear resistance of the serious worn surface is less than that of the slight worn surface in the future practical applications.

  1. Correlation of Effective Dispersive and Polar Surface Energies in Heterogeneous Self-Assembled Monolayer Coatings

    DEFF Research Database (Denmark)

    Zhuang, Yanxin; Hansen, Ole

    2009-01-01

    grown oil oxidized (100) silicon Surfaces in a vapor phase process using five different precursors. Experimentally, effective surface energy components of the fluorocarbon self-assembled monolayers were determined from measured contact angles using the Owens-Wendt-Rabel-Kaelble method. We show...

  2. Fracture surface energy of the Punchbowl fault, San Andreas system.

    Science.gov (United States)

    Chester, Judith S; Chester, Frederick M; Kronenberg, Andreas K

    2005-09-01

    Fracture energy is a form of latent heat required to create an earthquake rupture surface and is related to parameters governing rupture propagation and processes of slip weakening. Fracture energy has been estimated from seismological and experimental rock deformation data, yet its magnitude, mechanisms of rupture surface formation and processes leading to slip weakening are not well defined. Here we quantify structural observations of the Punchbowl fault, a large-displacement exhumed fault in the San Andreas fault system, and show that the energy required to create the fracture surface area in the fault is about 300 times greater than seismological estimates would predict for a single large earthquake. If fracture energy is attributed entirely to the production of fracture surfaces, then all of the fracture surface area in the Punchbowl fault could have been produced by earthquake displacements totalling <1 km. But this would only account for a small fraction of the total energy budget, and therefore additional processes probably contributed to slip weakening during earthquake rupture.

  3. Low energy He+ irradiation effect on graphite surface

    International Nuclear Information System (INIS)

    Asari, E.; Nakamura, K.G.; Kitajima, M.; Kawabe, T.

    1992-01-01

    Study on the lattice disordering and the secondary electron emission under low energy (1-5keV) He + irradiation is reported. Real-time Raman measurements show that difference in the observed Raman spectra for different ion energies is due to the difference of the damage depth. The relation between the observed Raman spectrum and the depth profile of lattice damage is discussed. Energy dependence of the secondary electron emission coefficient are also described. (author)

  4. Influence of the target surface contamination on UHV screening energies

    Energy Technology Data Exchange (ETDEWEB)

    Targosz-Sleczka, N; Czerski, K; Kilic, A I [Institute of Physics, University of Szczecin, Szczecin (Poland); Huke, A; Martin, L; Heide, P [Institut fuer Atomare Physik und Optik, Technische Universitaet Berlin, Berlin (Germany); Blauth, D; Winter, H, E-mail: natalia.targosz@wmf.univ.szczecin.p [Institut fuer Physik, Humboldt-Universitaet zu Berlin, Berlin (Germany)

    2010-01-01

    The d + d fusion reactions have been investigated in the Zirconium environment under ultra high vacuum (UHV) conditions for projectile energies below 30 keV. The experimentally determined screening energy value of 497 {+-} 7 eV is larger than the previous results by a factor of almost two. Despite the UHV conditions a small deviation between experimental data and the theoretical curve arising from the target surface contamination could be still observed at the lowest projectile energies. Calculations made under the assumption of formation of a Zirconium oxide contamination, show that every atomic monolayer reduces the estimated screening energy significantly.

  5. Influence of the target surface contamination on UHV screening energies

    International Nuclear Information System (INIS)

    Targosz-Sleczka, N; Czerski, K; Kilic, A I; Huke, A; Martin, L; Heide, P; Blauth, D; Winter, H

    2010-01-01

    The d + d fusion reactions have been investigated in the Zirconium environment under ultra high vacuum (UHV) conditions for projectile energies below 30 keV. The experimentally determined screening energy value of 497 ± 7 eV is larger than the previous results by a factor of almost two. Despite the UHV conditions a small deviation between experimental data and the theoretical curve arising from the target surface contamination could be still observed at the lowest projectile energies. Calculations made under the assumption of formation of a Zirconium oxide contamination, show that every atomic monolayer reduces the estimated screening energy significantly.

  6. Building energy efficiency in different climates

    International Nuclear Information System (INIS)

    Lam, Joseph C.; Wan, Kevin K.W.; Tsang, C.L.; Yang Liu

    2008-01-01

    Energy simulation was conducted for office buildings in the five major climate zones - severe cold, cold, hot summer and cold winter, mild, and hot summer and warm winter - in China using DOE-2.1E. The primary aim was to investigate the thermal and energy performance of office buildings with centralised heating, ventilation and air conditioning plants in the major climatic zones in China. The computed results were analysed in three aspects - heating load, cooling load and the corresponding building energy consumption. The building peak monthly heating load varied from 142 MW h (1033 MW h cooling) in Hong Kong to 447 MW h (832 MW h cooling) in Harbin. It was also found that passive solar designs could have large energy savings potential in the severe cold and cold climates. In Harbin, the window solar component helped lower the annual building heating load by 650 MW h. Internal loads (lighting and office equipment) and part load operations of fans and pumps also played a significant role in the overall building energy efficiency. This paper presents the work, its findings and energy efficiency implications

  7. [Corrosion resistant properties of different anodized microtopographies on titanium surfaces].

    Science.gov (United States)

    Fangjun, Huo; Li, Xie; Xingye, Tong; Yueting, Wang; Weihua, Guo; Weidong, Tian

    2015-12-01

    To investigate the corrosion resistant properties of titanium samples prepared by anodic oxidation with different surface morphologies. Pure titanium substrates were treated by anodic oxidation to obtain porous titanium films in micron, submicron, and micron-submicron scales. The surface morphologies, coating cross-sectional morphologies, crystalline structures, and surface roughness of these samples were characterized. Electrochemical technique was used to measure the corrosion potential (Ecorr), current density of corrosion (Icorr), and polarization resistance (Rp) of these samples in a simulated body fluid. Pure titanium could be modified to exhibit different surface morphologies by the anodic oxidation technique. The Tafel curve results showed that the technique can improve the corrosion resistance of pure titanium. Furthermore, the corrosion resistance varied with different surface morphologies. The submicron porous surface sample demonstrated the best corrosion resistance, with maximal Ecorr and Rp and minimal Icorr. Anodic oxidation technology can improve the corrosion resistance of pure titanium in a simulated body fluid. The submicron porous surface sample exhibited the best corrosion resistance because of its small surface area and thick barrier layer.

  8. The puckering free-energy surface of proline

    Directory of Open Access Journals (Sweden)

    Di Wu

    2013-03-01

    Full Text Available Proline has two preferred puckering states, which are often characterized by the pseudorotation phase angle and amplitude. Although proline's five endocyclic torsion angles can be utilized to calculate the phase angle and amplitude, it is not clear if there is any direct correlation between each torsion angle and the proline-puckering pathway. Here we have designed five proline puckering pathways utilizing each torsion angle χj (j = 1∼5 as the reaction coordinate. By examining the free-energy surfaces of the five puckering pathways, we find they can be categorized into two groups. The χ2 pathway (χ2 is about the Cβ—Cγ bond is especially meaningful in describing proline puckering: it changes linearly with the puckering amplitude and symmetrically with the phase angle. Our results show that this conclusion applies to both trans and cis proline conformations. We have also analyzed the correlations of proline puckering and its backbone torsion angles ϕ and ψ. We show proline has preferred puckering states at the specific regions of ϕ, ψ angles. Interestingly, the shapes of ψ-χ2 free-energy surfaces are similar among the trans proline in water, cis proline in water and cis proline in the gas phase, but they differ substantially from that of the trans proline in the gas phase. Our calculations are conducted using molecular simulations; we also verify our results using the proline conformations selected from the Protein Data Bank. In addition, we have compared our results with those calculated by the quantum mechanical methods.

  9. Surface relaxation and surface energy of face –centered Cubic ...

    African Journals Online (AJOL)

    DR. MIKE HORSFALL

    Surface relaxation and surface energy of face –centered Cubic metals. 1AGHEMENLO H E; *2IYAYI, S E; 3AVWIRI ,G O. 1, 3 Department of Physics, Ambrose Alli University, Ekpoma, Nigeria. 2 Department of Physics, University of Benin, Benin City, Nigeria. 3 Department of Physics, University of Port Harcourt, PH, Nigeria.

  10. An accurate global potential energy surface, dipole moment surface, and rovibrational frequencies for NH3

    Science.gov (United States)

    Huang, Xinchuan; Schwenke, David W.; Lee, Timothy J.

    2008-12-01

    A global potential energy surface (PES) that includes short and long range terms has been determined for the NH3 molecule. The singles and doubles coupled-cluster method that includes a perturbational estimate of connected triple excitations and the internally contracted averaged coupled-pair functional electronic structure methods have been used in conjunction with very large correlation-consistent basis sets, including diffuse functions. Extrapolation to the one-particle basis set limit was performed and core correlation and scalar relativistic contributions were included directly, while the diagonal Born-Oppenheimer correction was added. Our best purely ab initio PES, denoted "mixed," is constructed from two PESs which differ in whether the ic-ACPF higher-order correlation correction was added or not. Rovibrational transition energies computed from the mixed PES agree well with experiment and the best previous theoretical studies, but most importantly the quality does not deteriorate even up to 10300cm-1 above the zero-point energy (ZPE). The mixed PES was improved further by empirical refinement using the most reliable J =0-2 rovibrational transitions in the HITRAN 2004 database. Agreement between high-resolution experiment and rovibrational transition energies computed from our refined PES for J =0-6 is excellent. Indeed, the root mean square (rms) error for 13 HITRAN 2004 bands for J =0-2 is 0.023cm-1 and that for each band is always ⩽0.06cm-1. For J =3-5 the rms error is always ⩽0.15cm-1. This agreement means that transition energies computed with our refined PES should be useful in the assignment of new high-resolution NH3 spectra and in correcting mistakes in previous assignments. Ideas for further improvements to our refined PES and for extension to other isotopolog are discussed.

  11. Preparing Al-Mg Substrate for Thermal Spraying: Evaluation of Surface State After Different Pretreatments

    Science.gov (United States)

    Lukauskaitė, R.; Valiulis, A. V.; Černašėjus, O.; Škamat, J.; Rębiś, J. A.

    2016-08-01

    The article deals with the pretreatment technique for preparing the surface of aluminum alloy EN AW 5754 before thermal spray. The surface after different pretreatments, including degreasing with acetone, chemical etching with acidic and alkali solutions, grit-blasting, cathodic cleaning, and some combinations of these techniques, has been studied. The investigation of pre-treated surfaces covered the topographical study (using scanning electron microscopy, atomic force microscopy, and 3D profilometry), the chemical analysis by x-ray photoelectron spectroscopy, the evaluation of surface wettability (sessile drop method), and the assessment of surface free energy. Compared with all the techniques used in present work, the cathodic cleaning and its combination with grit-blasting provide the most preferable chemistry of the surface. Due to the absence of hydroxides at the surface and, possible, due to the diffusion of magnesium to the surface of substrate, the surface wettability and the surface free energy have been significantly improved. No direct correlation between the surface topography and the surface wettability has been established.

  12. Surface energies of metals in both liquid and solid states

    International Nuclear Information System (INIS)

    Aqra, Fathi; Ayyad, Ahmed

    2011-01-01

    Although during the last years one has seen a number of systematic studies of the surface energies of metals, the aim and the scientific meaning of this research is to establish a simple and a straightforward theoretical model to calculate accurately the mechanical and the thermodynamic properties of metal surfaces due to their important application in materials processes and in the understanding of a wide range of surface phenomena. Through extensive theoretical calculations of the surface tension of most of the liquid metals, we found that the fraction of broken bonds in liquid metals (f) is constant which is equal to 0.287. Using our estimated f value, the surface tension (γ m ), surface energy (γ SV ), surface excess entropy (-dγ/dT), surface excess enthalpy (H s ), coefficient of thermal expansion (α m and α b ), sound velocity (c m ) and its temperature coefficient (-dc/dT) have been calculated for more than sixty metals. The results of the calculated quantities agree well with available experimental data.

  13. Surface free energy analysis of adsorbents used for radioiodine adsorption

    International Nuclear Information System (INIS)

    González-García, C.M.; Román, S.; González, J.F.; Sabio, E.; Ledesma, B.

    2013-01-01

    In this work, the surface free energy of biomass-based activated carbons, both fresh and impregnated with triethylenediamine, has been evaluated. The contribution of Lifshitz van der Waals components was determined by the model proposed by van Oss et al. The results obtained allowed predicting the most probable configurations of the impregnant onto the carbon surface and its influence on the subsequent adsorption of radioactive methyl iodide.

  14. Calculated surface-energy anomaly in the 3d metals

    DEFF Research Database (Denmark)

    Aldén, M.; Skriver, Hans Lomholt; Mirbt, S.

    1992-01-01

    Local-spin-density theory and a Green’s-function technique based on the linear muffin-tin orbitals method have been used to calculate the surface energy of the 3d metals. The theory explains the variation of the values derived from measurements of the surface tension of liquid metals including...... the pronounced anomaly occurring between vanadium and nickel in terms of a decrease in the d contribution caused by spin polarization....

  15. Comparison of different surface quantitative analysis methods. Application to corium

    International Nuclear Information System (INIS)

    Guilbaud, N.; Blin, D.; Perodeaud, Ph.; Dugne, O.; Gueneau, Ch.

    2000-01-01

    In case of a severe hypothetical accident in a pressurized water reactor, the reactor assembly melts partially or completely. The material formed, called corium, flows out and spreads at the bottom of the reactor. To limit and control the consequences of such an accident, the specifications of the O-U-Zr basic system must be known accurately. To achieve this goal, the corium mix was melted by electron bombardment at very high temperature (3000 K) followed by quenching of the ingot in the Isabel 1 evaporator. Metallographic analyses were then required to validate the thermodynamic databases set by the Thermo-Calc software. The study consists in defining an overall surface quantitative analysis method that is fast and reliable, in order to determine the overall corium composition. The analyzed ingot originated in a [U+Fe+Y+UO 2 +ZrO 2 ) mix, with a total mass of 2253.7 grams. Several successive heating with average power were performed before a very brief plateau at very high temperature, so that the ingot was formed progressively and without any evaporation liable to modify its initial composition. The central zone of the ingot was then analyzed by qualitative and quantitative global surface methods, to yield the volume composition of the analyzed zone. Corium sample analysis happens to be very complex because of the variety and number of elements present, and also because of the presence of oxygen in a heavy element like the uranium based matrix. Three different global quantitative surface analysis methods were used: global EDS analysis (Energy Dispersive Spectrometry), with SEM, global WDS analysis (Wavelength Dispersive Spectrometry) with EPMA, and coupling of image analysis with EDS or WDS point spectroscopic analyses. The difficulties encountered during the study arose from sample preparation (corium is very sensitive to oxidation), and the choice of acquisition parameters of the images and analyses. The corium sample studied consisted of two zones displaying

  16. An adaptive interpolation scheme for molecular potential energy surfaces

    Science.gov (United States)

    Kowalewski, Markus; Larsson, Elisabeth; Heryudono, Alfa

    2016-08-01

    The calculation of potential energy surfaces for quantum dynamics can be a time consuming task—especially when a high level of theory for the electronic structure calculation is required. We propose an adaptive interpolation algorithm based on polyharmonic splines combined with a partition of unity approach. The adaptive node refinement allows to greatly reduce the number of sample points by employing a local error estimate. The algorithm and its scaling behavior are evaluated for a model function in 2, 3, and 4 dimensions. The developed algorithm allows for a more rapid and reliable interpolation of a potential energy surface within a given accuracy compared to the non-adaptive version.

  17. Exchange energy of inhomogenous electron gas near a metal surface

    International Nuclear Information System (INIS)

    Miglio, L.; Tosi, M.P.; March, N.H.

    1980-12-01

    Using the first-order density matrix of an infinite-barrier model of a metal surface, the exchange energy density can be evaluated exactly as a function of distance z from the barrier. This result is compared with the local approximation -3/4e 2 (3/π)sup(1/3) rhosup(4/3)(z) where rho is the electron density in the model. The local approximation is demonstrated to be quantitatively accurate at all z. The integrated surface exchange energy is given to within 3% by the local theory. (author)

  18. Surface segregation energies in transition-metal alloys

    DEFF Research Database (Denmark)

    Ruban, Andrei; Skriver, Hans Lomholt; Nørskov, Jens Kehlet

    1999-01-01

    We present a database of 24 x 24 surface segregation energies of single transition metal impurities in transition-metal hosts obtained by a Green's-function linear-muffin-tin-orbitals method in conjunction with the coherent potential and atomic sphere approximations including a multipole correction...... to the electrostatic potential and energy. We use the database to establish the major factors which govern surface segregation in transition metal alloys. We find that the calculated trends are well described by Friedel's rectangular state density model and that the few but significant deviations from the simple...

  19. Kinetic-energy functionals studied by surface calculations

    DEFF Research Database (Denmark)

    Vitos, Levente; Skriver, Hans Lomholt; Kollár, J.

    1998-01-01

    The self-consistent jellium model of metal surfaces is used to study the accuracy of a number of semilocal kinetic-energy functionals for independent particles. It is shown that the poor accuracy exhibited by the gradient expansion approximation and most of the semiempirical functionals in the lo...... density, high gradient limit may be subtantially improved by including locally a von Weizsacker term. Based on this, we propose a simple one-parameter Pade's approximation, which reproduces the exact Kohn-Sham surface kinetic energy over the entire range of metallic densities....

  20. Self-energies and the interactions of particles with surfaces

    International Nuclear Information System (INIS)

    Manson, J.R.; Ritchie, R.H.; Echenique, P.M.; Gras-Marti, A.

    1987-01-01

    We have in this paper reviewed the method of treating many-body problems by means of an effective interaction self-energy. We have developed an alternatvie approach to the self-energy which is simpler and more straight-forward than standard methods, and we have illustrated its use with two examples of a charge interacting with a metal surface. In each case the self-energy produces the classical image potential together with corrections due to quantum mechanical effects. This method has also been successfully applied to the problem of an atom interacting with a surface. Corrections to the Van der Waals dispersion force are obtained, and via the non-conservative imaginary parts to /summation//sub i/(z) we discuss transition rates and energy exchange. 14 refs., 1 fig

  1. Different methods for waste to energy transformation

    NARCIS (Netherlands)

    Koning, J. de

    1998-01-01

    In the past 25 years, many technological developments have taken place in the thermal treatment of Municipal Solid Waste (MSW). Apart from the initials goal of the technology (i.e., volume reduction and inertisation), flue gas emissions, solid residues, energy efficiency and economics became

  2. Surface Passivation and Junction Formation Using Low Energy Hydrogen Implants

    Science.gov (United States)

    Fonash, S. J.

    1985-01-01

    New applications for high current, low energy hydrogen ion implants on single crystal and polycrystal silicon grain boundaries are discussed. The effects of low energy hydrogen ion beams on crystalline Si surfaces are considered. The effect of these beams on bulk defects in crystalline Si is addressed. Specific applications of H+ implants to crystalline Si processing are discussed. In all of the situations reported on, the hydrogen beams were produced using a high current Kaufman ion source.

  3. Free energy surfaces in the superconducting mixed state

    Science.gov (United States)

    Finnemore, D. K.; Fang, M. M.; Bansal, N. P.; Farrell, D. E.

    1989-01-01

    The free energy surface for Tl2Ba2Ca2Cu3O1O has been measured as a function of temperature and magnetic field to determine the fundamental thermodynamic properties of the mixed state. The change in free energy, G(H)-G(O), is found to be linear in temperature over a wide range indicating that the specific heat is independent of field.

  4. He-, Ne-, and Ar-phosgene intermolecular potential energy surfaces

    DEFF Research Database (Denmark)

    Munteanu, Cristian R.; Henriksen, Christian; Felker, Peter M.

    2013-01-01

    Using the CCSD(T) model, we evaluated the intermolecular potential energy surfaces of the He-, Ne-, and Ar-phosgene complexes. We considered a representative number of intermolecular geometries for which we calculated the corresponding interaction energies with the augmented (He complex) and doub...... of the complexes, providing valuable results for future experimental investigations. Comparing our results to those previously available for other phosgene complexes, we suggest that the results for Cl2-phosgene should be revised....

  5. Testing and evaluation of different energy storage devices for piezoelectric energy harvesting under road conditions

    Science.gov (United States)

    Gopalakrishnan, Pratheek

    The increasing needs in green technology have propelled the rapid development in energy conversion and the advancement of electric energy storage systems. A viable storage technology is needed to store intermittent electrical energy in different electronic applications. In this thesis, recent progress on the chemistry and design of batteries is summarized with their challenges and improvements. Along with that, electrolytic capacitors are also reviewed with their types, advantages and disadvantages of each in short. Super capacitors having higher surface area and thinner dielectrics than conventional capacitors along with hybrid capacitors, are discussed in detail. The potential of a hybrid capacitor, Ni(OH)2/ Active Carbon, compared with Ni-Cd batteries and electrolytic capacitors in the application of energy storage for high way energy harvesting has been explored in this work. Both the battery and the hybrid capacitor has been tested under various experimental conditions and their properties in relation to their chemical compositions are compared. The results obtained from the experiments have been analyzed and the most suitable energy storage devices have been selected with their application potential evaluated before drawing conclusion reported in this thesis.

  6. Surface-induced dissociation and chemical reactions of C2D4(+) on stainless steel, carbon (HOPG), and two different diamond surfaces.

    Science.gov (United States)

    Feketeová, Linda; Zabka, Jan; Zappa, Fabio; Grill, Verena; Scheier, Paul; Märk, Tilmann D; Herman, Zdenek

    2009-06-01

    Surface-induced interactions of the projectile ion C(2)D(4)(+) with room-temperature (hydrocarbon covered) stainless steel, carbon highly oriented pyrolytic graphite (HOPG), and two different types of diamond surfaces (O-terminated and H-terminated) were investigated over the range of incident energies from a few eV up to 50 eV. The relative abundance of the product ions in dependence on the incident energy of the projectile ion [collision-energy resolved mass spectra, (CERMS) curves] was determined. The product ion mass spectra contained ions resulting from direct dissociation of the projectile ions, from chemical reactions with the hydrocarbons on the surface, and (to a small extent) from sputtering of the surface material. Sputtering of the surface layer by low-energy Ar(+) ions (5-400 eV) indicated the presence of hydrocarbons on all studied surfaces. The CERMS curves of the product ions were analyzed to obtain both CERMS curves for the products of direct surface-induced dissociation of the projectile ion and CERMS curves of products of surface reactions. From the former, the fraction of energy converted in the surface collision into the internal excitation of the projectile ion was estimated as 10% of the incident energy. The internal energy of the surface-excited projectile ions was very similar for all studied surfaces. The H-terminated room-temperature diamond surface differed from the other surfaces only in the fraction of product ions formed in H-atom transfer surface reactions (45% of all product ions formed versus 70% on the other surfaces).

  7. Effect of cocoa fat content on wetting and surface energy of chocolate

    Directory of Open Access Journals (Sweden)

    Lubomír Lapčík

    2017-01-01

    Full Text Available The aim of this study was the quantification of the effect of the cocoa fat content on the wetting characteristics and surface free energy of different chocolate compositions. On the market, there are many different types of chocolate products which differ both in the sensory and physico-chemical properties together with their raw material compositions and the contents of the individual components. This paper focuses on differences in the use of different types of fats - cocoa butter, milk fat, equivalents or cocoa butter substitutes in chocolate products. Studied samples (prepared at Carla, Ltd. Company were followed by static contact angles of wetting measurements and by calculated surface free energies. There were investigated the effects of fat content and used fat types of the chocolate products on their final wettabilities and resulting surface free energies. There was found a linear dependence between total fat content and the surface free energy, which was gradually increasing with increasing fat content. Additionally, there were performed TG DTG and NIR spectrometry measurements of the tested materials with the aim to determine the melting point of studied fats used, as well as to determine and identify individual fat components of chocolate products which may affect the resulting value of surface free energy.

  8. Re-examination of the threshold energy surface in copper

    International Nuclear Information System (INIS)

    King, W.E.; Benedek, R.; Merkle, K.L.; Meshii, M.

    1981-01-01

    Radiation-induced defect production in copper has been studied using in-situ electrical resistivity damage-rate measurements in the HVEM and molecular dynamics simulations. Analysis of the results yields a threshold energy surface characterized by two isolated pockets of low threshold energy centered at and surrounded by regions of much higher threshold energy; the corresponding damage function exhibits a plateau at 0.65 Frenkel pairs. A Frenkel pair resistivity of (2.75/sub -0.2/ + 0 6 ) x 10 - 4 Ω-cm is proposed. A model damage function is constructed and compared to results from ion irradiation damage-rate measurements. 7 figures

  9. Energy utilization in surface mining project : with case study illustration

    International Nuclear Information System (INIS)

    Sinha, D.K.; De, Amitosh

    1992-01-01

    The importance of reducing energy consumption per tonne of output in the mining projects needs an innovative approach and style to change the behaviour and postures of the technical characteristics. The need for suitable energy policy can not be overlooked with the addition of new large size surface mining projects having a lot of technological development. But the immediate prescription to the problem is to pinpoint specific high energy consuming areas prefixed by thorough diagnosis and followed by deep scientific thought into it. To that extent this paper makes a primary attempt to characterise the various problems. (author). 7 tabs

  10. Cell behavior on microparticles with different surface morphology

    International Nuclear Information System (INIS)

    Huang Sha; Fu Xiaobing

    2010-01-01

    Microparticles can serve as substrates for cell amplification and deliver the cell aggregation to the site of the defect for tissue regeneration. To develop favorable microparticles for cell delivery application, we fabricated and evaluated three types of microparticles that differ in surface properties. The microparticles with varied surface morphology (smooth, pitted and multicavity) were created from chemically crosslinked gelatin particles that underwent various drying treatments. Three types of microparticles were characterized and assessed in terms of the cell behavior of human keratinocytes and fibroblasts seeded on them. The cells could attach, spread and proliferate on all types of microparticles but spread and populated more slowly on the microparticles with smooth surfaces than on those with pitted or multicavity surfaces. Microparticles with a multicavity surface demonstrated the highest cell attachment and growth rate. Furthermore, cells tested on microparticles with a multicavity surface exhibited better morphology and induced the earlier formation of extracellular-based cell-microparticle aggregation than those on microparticles with other surface morphology (smooth and pitted). Thus, microparticles with a multicavity surface show promise for attachment and proliferation of cells in tissue engineering.

  11. Constructing a multidimensional free energy surface like a spider weaving a web.

    Science.gov (United States)

    Chen, Changjun

    2017-10-15

    Complete free energy surface in the collective variable space provides important information of the reaction mechanisms of the molecules. But, sufficient sampling in the collective variable space is not easy. The space expands quickly with the number of the collective variables. To solve the problem, many methods utilize artificial biasing potentials to flatten out the original free energy surface of the molecule in the simulation. Their performances are sensitive to the definitions of the biasing potentials. Fast-growing biasing potential accelerates the sampling speed but decreases the accuracy of the free energy result. Slow-growing biasing potential gives an optimized result but needs more simulation time. In this article, we propose an alternative method. It adds the biasing potential to a representative point of the molecule in the collective variable space to improve the conformational sampling. And the free energy surface is calculated from the free energy gradient in the constrained simulation, not given by the negative of the biasing potential as previous methods. So the presented method does not require the biasing potential to remove all the barriers and basins on the free energy surface exactly. Practical applications show that the method in this work is able to produce the accurate free energy surfaces for different molecules in a short time period. The free energy errors are small in the cases of various biasing potentials. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  12. Inelastic surface vibrations versus energy-dependent nucleus ...

    Indian Academy of Sciences (India)

    Limitations of the static Woods–Saxon potential and the applicability of the energy dependent Woods–Saxon potential (EDWSP) model within the framework of one-dimensional Wong formula to explore the sub-barrier fusion data are highlighted. The inelastic surface excitations of the fusing nuclei are found to be ...

  13. Inelastic surface vibrations versus energy-dependent nucleus ...

    Indian Academy of Sciences (India)

    Abstract. Limitations of the static Woods–Saxon potential and the applicability of the energy- dependent Woods–Saxon potential (EDWSP) model within the framework of one-dimensional. Wong formula to explore the sub-barrier fusion data are highlighted. The inelastic surface exci- tations of the fusing nuclei are found to ...

  14. The evaporative fraction as a measure of surface energy partitioning

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, W.E. [Pacific Northwest Lab., Richland, WA (United States); Cuenca, R.H. [Oregon State Univ., Corvallis, OR (United States)

    1990-12-31

    The evaporative fraction is a ratio that expresses the proportion of turbulent flux energy over land surfaces devoted to evaporation and transpiration (evapotranspiration). It has been used to characterize the energy partition over land surfaces and has potential for inferring daily energy balance information based on mid-day remote sensing measurements. The HAPEX-MOBILHY program`s SAMER system provided surface energy balance data over a range of agricultural crops and soil types. The databases from this large-scale field experiment was analyzed for the purpose of studying the behavior and daylight stability of the evaporative fraction in both ideal and general meteorological conditions. Strong linear relations were found to exist between the mid-day evaporative fraction and the daylight mean evaporative fraction. Statistical tests however rejected the hypothesis that the two quantities were equal. The relations between the evaporative fraction and the surface soil moisture as well as soil moisture in the complete vegetation root zone were also explored.

  15. The evaporative fraction as a measure of surface energy partitioning

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, W.E. (Pacific Northwest Lab., Richland, WA (United States)); Cuenca, R.H. (Oregon State Univ., Corvallis, OR (United States))

    1990-01-01

    The evaporative fraction is a ratio that expresses the proportion of turbulent flux energy over land surfaces devoted to evaporation and transpiration (evapotranspiration). It has been used to characterize the energy partition over land surfaces and has potential for inferring daily energy balance information based on mid-day remote sensing measurements. The HAPEX-MOBILHY program's SAMER system provided surface energy balance data over a range of agricultural crops and soil types. The databases from this large-scale field experiment was analyzed for the purpose of studying the behavior and daylight stability of the evaporative fraction in both ideal and general meteorological conditions. Strong linear relations were found to exist between the mid-day evaporative fraction and the daylight mean evaporative fraction. Statistical tests however rejected the hypothesis that the two quantities were equal. The relations between the evaporative fraction and the surface soil moisture as well as soil moisture in the complete vegetation root zone were also explored.

  16. Cleaning of biomaterial surfaces: protein removal by different solvents.

    Science.gov (United States)

    Kratz, Fabian; Grass, Simone; Umanskaya, Natalia; Scheibe, Christian; Müller-Renno, Christine; Davoudi, Neda; Hannig, Matthias; Ziegler, Christiane

    2015-04-01

    The removal of biofilms or protein films from biomaterials is still a challenging task. In particular, for research investigations on real (applied) surfaces the reuse of samples is of high importance, because reuse allows the comparison of the same sample in different experiments. The aim of the present study was to evaluate the cleaning efficiency of different solvents (SDS, water, acetone, isopropanol, RIPA-buffer and Tween-20) on five different biomaterials (titanium, gold, PMMA (no acetone used), ceramic, and PTFE) with different wettability which were covered by layers of two different adsorbed proteins (BSA and lysozyme). The presence of a protein film after adsorption was confirmed by transmission electron microscopy (TEM). After treatment of the surfaces with the different solvents, the residual proteins on the surface were determined by BCA-assay (bicinchoninic acid assay). Data of the present study indicate that SDS is an effective solvent, but for several protein-substrate combinations it does not show the cleaning efficiency often mentioned in literature. RIPA-buffer and Tween-20 were more effective. They showed very low residual protein amounts after cleaning on all examined material surfaces and for both proteins, however, with small differences for the respective substrate-protein combinations. RIPA-buffer in combination with ultrasonication completely removed the protein layer as confirmed by TEM. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Cell behavior related to implant surfaces with different microstructure and chemical composition: an in vitro analysis.

    Science.gov (United States)

    Conserva, Enrico; Lanuti, Anna; Menini, Maria

    2010-01-01

    This paper reports on an in vitro comparison of osteoblast and mesenchymal stem cell (MSC) adhesion, proliferation, and differentiation related to two different surface treatments applied to the same implant design to determine whether the interaction between cells and implants is influenced by surface structure and chemical composition of the implants. Thirty-nine implants with a sandblasted (SB) surface and 39 implants with a grit-blasted and high-temperature acid-etched (GBAE) surface were used. The implant macrostructures and microstructures were analyzed by high- and low-voltage scanning electron microscopy (SEM) and by stereo-SEM. The surface chemical composition was investigated by energy dispersive analysis and x-ray photoemission spectroscopy. SaOS-2 osteoblasts and human MSCs were used for the evaluation of cell proliferation and alkaline phosphatase enzymatic activity in contact with the two surfaces. The GBAE surface showed fewer contaminants and a very high percentage of titanium (19.7%) compared to the SB surface (14.2%). The two surfaces showed similar mean roughness (Ra), but the depth (Rz) and density (RSm) of the porosity were significantly increased in the GBAE surface. The GBAE surface presented more osteoblast and MSC proliferation than the SB surface. No statistically significant differences in alkaline phosphatase activity were found between surfaces for either cellular line. The GBAE surface showed less surface contaminants and a higher percentage of titanium (19.7%) than the SB surface. The macro/micropore structured design and chemical composition of the GBAE surface allowed greater cell adhesion and proliferation and an earlier cell spreading but did not play an obvious role in in vitro cellular differentiation.

  18. Modelling of low energy ion sputtering from oxide surfaces

    International Nuclear Information System (INIS)

    Kubart, T; Nyberg, T; Berg, S

    2010-01-01

    The main aim of this work is to present a way to estimate the values of surface binding energy for oxides. This is done by fitting results from the binary collisions approximation code Tridyn with data from the reactive sputtering processing curves, as well as the elemental composition obtained from x-ray photoelectron spectroscopy (XPS). Oxide targets of Al, Ti, V, Nb and Ta are studied. The obtained surface binding energies are then used to predict the partial sputtering yields. Anomalously high sputtering yield is observed for the TiO 2 target. This is attributed to the high sputtering yield of Ti lower oxides. Such an effect is not observed for the other studied metals. XPS measurement of the oxide targets confirms the formation of suboxides during ion bombardment as well as an oxygen deficient surface in the steady state. These effects are confirmed from the processing curves from the oxide targets showing an elevated sputtering rate in pure argon.

  19. Surface energy and radiation balance systems - General description and improvements

    Science.gov (United States)

    Fritschen, Leo J.; Simpson, James R.

    1989-01-01

    Surface evaluation of sensible and latent heat flux densities and the components of the radiation balance were desired for various vegetative surfaces during the ASCOT84 experiment to compare with modeled results and to relate these values to drainage winds. Five battery operated data systems equipped with sensors to determine the above values were operated for 105 station days during the ASCOT84 experiment. The Bowen ratio energy balance technique was used to partition the available energy into the sensible and latent heat flux densities. A description of the sensors and battery operated equipment used to collect and process the data is presented. In addition, improvements and modifications made since the 1984 experiment are given. Details of calculations of soil heat flow at the surface and an alternate method to calculate sensible and latent heat flux densities are provided.

  20. Urbanization Process and Variation of Energy Budget of Land Surfaces

    Directory of Open Access Journals (Sweden)

    Ciro Gardi

    2007-06-01

    Full Text Available Urban areas are increasing at a rate much higher than human population growth in many part of the world; actually more than 73 towns in the world are larger than 1000 km2. The European Environmental Agency indicates an urban area average growth rate, over the last 20 years, of 20%. The urbanization process, and the consequent soil sealing, determines not only the losses of the ecological functions of the soil, but also a variation of the energy budget of land surfaces, that affect the microclimatic conditions (heat islands. The alteration of the energy budget are determined by the variations of albedo and roughness of surfaces, but especially by the net losses of evapotranspirating areas. In the present research we have assessed the variation of Parma territory energy budget, induced by the change in land use over the last 122 years. The urban area increase between 1881 and 2003 was 535%.

  1. Exploring the free energy surfaces of clusters using reconnaissance metadynamics

    Science.gov (United States)

    Tribello, Gareth A.; Cuny, Jérôme; Eshet, Hagai; Parrinello, Michele

    2011-09-01

    A new approach is proposed for exploring the low-energy structures of small to medium-sized aggregates of atoms and molecules. This approach uses the recently proposed reconnaissance metadynamics method [G. A. Tribello, M. Ceriotti, and M. Parrinello. Proc. Natl. Acad. Sci. U.S.A. 107(41), 17509 (2010), 10.1073/pnas.1011511107] in tandem with collective variables that describe the average structure of the coordination sphere around the atoms/molecules. We demonstrate this method on both Lennard-Jones and water clusters and show how it is able to quickly find the global minimum in the potential energy surface, while exploring the finite temperature free energy surface.

  2. Communication: Fitting potential energy surfaces with fundamental invariant neural network

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Kejie; Chen, Jun; Zhao, Zhiqiang; Zhang, Dong H., E-mail: zhangdh@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People’s Republic of China and University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China. (China)

    2016-08-21

    A more flexible neural network (NN) method using the fundamental invariants (FIs) as the input vector is proposed in the construction of potential energy surfaces for molecular systems involving identical atoms. Mathematically, FIs finitely generate the permutation invariant polynomial (PIP) ring. In combination with NN, fundamental invariant neural network (FI-NN) can approximate any function to arbitrary accuracy. Because FI-NN minimizes the size of input permutation invariant polynomials, it can efficiently reduce the evaluation time of potential energy, in particular for polyatomic systems. In this work, we provide the FIs for all possible molecular systems up to five atoms. Potential energy surfaces for OH{sub 3} and CH{sub 4} were constructed with FI-NN, with the accuracy confirmed by full-dimensional quantum dynamic scattering and bound state calculations.

  3. Surface effects on sputtered atoms and their angular and energy dependence

    International Nuclear Information System (INIS)

    Hassanein, A.M.

    1985-04-01

    A comprehensive three-dimensional Monte Carlo computer code, Ion Transport in Materials and Compounds (ITMC), has been developed to study in detail the surfaces related phenomena that affect the amount of sputtered atoms and back-scattered ions and their angular and energy dependence. A number of important factors that can significantly affect the sputtering behavior of a surface can be studied in detail, such as having different surface properties and composition than the bulk and synergistic effects due to surface segregation of alloys. These factors can be important in determining and lifetime of fusion reactor first walls and limiters. The ITMC Code is based on Monte Carlo methods to track down the path and the damage produced by charged particles as they slow down in solid metal surfaces or compounds. The major advantages of the ITMC code are its flexibility and ability to use and compare all existing models for energy losses, all known interatomic potentials, and to use different materials and compounds with different surface and bulk composition to allow for dynamic surface composition to allow for dynamic surface composition changes. There is good agreement between the code and available experimental results without using adjusting parameters for the energy losses mechanisms. The ITMC Code is highly optimized, very fast to run and easy to use

  4. Impact of Dust on Mars Surface Albedo and Energy Flux with LMD General Circulation Model

    Science.gov (United States)

    Singh, D.; Flanner, M.; Millour, E.; Martinez, G.

    2015-12-01

    Mars, just like Earth experience different seasons because of its axial tilt (about 25°). This causes growth and retreat of snow cover (primarily CO2) in Martian Polar regions. The perennial caps are the only place on the planet where condensed H2O is available at surface. On Mars, as much as 30% atmospheric CO2 deposits in each hemisphere depending upon the season. This leads to a significant variation on planet's surface albedo and hence effecting the amount of solar flux absorbed or reflected at the surface. General Circulation Model (GCM) of Laboratoire de Météorologie Dynamique (LMD) currently uses observationally derived surface albedo from Thermal Emission Spectrometer (TES) instrument for the polar caps. These TES albedo values do not have any inter-annual variability, and are independent of presence of any dust/impurity on surface. Presence of dust or other surface impurities can significantly reduce the surface albedo especially during and right after a dust storm. This change will also be evident in the surface energy flux interactions. Our work focuses on combining earth based Snow, Ice, and Aerosol Radiation (SNICAR) model with current state of GCM to incorporate the impact of dust on Martian surface albedo, and hence the energy flux. Inter-annual variability of surface albedo and planet's top of atmosphere (TOA) energy budget along with their correlation with currently available mission data will be presented.

  5. Summertime influences of tidal energy advection on the surface energy balance in a mangrove forest

    Directory of Open Access Journals (Sweden)

    J. G. Barr

    2013-01-01

    Full Text Available Mangrove forests are ecosystems susceptible to changing water levels and temperatures due to climate change as well as perturbations resulting from tropical storms. Numerical models can be used to project mangrove forest responses to regional and global environmental changes, and the reliability of these models depends on surface energy balance closure. However, for tidal ecosystems, the surface energy balance is complex because the energy transport associated with tidal activity remains poorly understood. This study aimed to quantify impacts of tidal flows on energy dynamics within a mangrove ecosystem. To address the research objective, an intensive 10-day study was conducted in a mangrove forest located along the Shark River in the Everglades National Park, FL, USA. Forest–atmosphere turbulent exchanges of energy were quantified with an eddy covariance system installed on a 30-m-tall flux tower. Energy transport associated with tidal activity was calculated based on a coupled mass and energy balance approach. The mass balance included tidal flows and accumulation of water on the forest floor. The energy balance included temporal changes in enthalpy, resulting from tidal flows and temperature changes in the water column. By serving as a net sink or a source of available energy, flood waters reduced the impact of high radiational loads on the mangrove forest. Also, the regression slope of available energy versus sink terms increased from 0.730 to 0.754 and from 0.798 to 0.857, including total enthalpy change in the water column in the surface energy balance for 30-min periods and daily daytime sums, respectively. Results indicated that tidal inundation provides an important mechanism for heat removal and that tidal exchange should be considered in surface energy budgets of coastal ecosystems. Results also demonstrated the importance of including tidal energy advection in mangrove biophysical models that are used for predicting ecosystem

  6. Osteoblast response to zirconia surfaces with different topographies

    Energy Technology Data Exchange (ETDEWEB)

    Herath, H.M.T.U. [Department of Medical Laboratory Science, Faculty of Allied Health Sciences, University of Peradeniya (Sri Lanka); Di Silvio, L. [Guy' s, King' s and St Thomas' Medical and Dental Institute, King' s College London, London SE1 9RT (United Kingdom); Evans, J.R.G., E-mail: j.r.g.evans@ucl.ac.uk [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

    2015-12-01

    Zirconia-3 mol% yttria ceramics were prepared with as-sintered, abraded, polished, and porous surfaces in order to explore the attachment, proliferation and differentiation of osteoblast-like cells. After modification, all surfaces were heated to 600 °C to extinguish traces of organic contamination. All surfaces supported cell attachment, proliferation and differentiation but the surfaces with grain boundary grooves or abraded grooves provided conditions for enhanced initial cell attachment. Nevertheless, overall cell proliferation and total DNA were highest on the polished surface. Zirconia sintered at a lower temperature (1300 °C vs. 1450 °C) had open porosity and presented reduced proliferation as assessed by alamarBlue™ assay, possibly because the openness of the pores prevented cells developing a local microenvironment. All cells retained the typical polygonal morphology of osteoblast-like cells with variations attributable to the underlying surface notably alignment along the grooves of the abraded surface. - Highlights: • Biocompatibility of chemically identical, topologically different ZrO{sub 2} was tested. • ZrO{sub 2} promoted cell adhesion, proliferation, differentiation and nodule formation. • Proliferation was high on polished ZrO{sub 2} but initial recruitment was high on abraded ZrO{sub 2}. • With open porosity, proliferation was low; cells cannot establish a microenvironment.

  7. Seasonal contrast in the surface energy balance of the Sahel

    Science.gov (United States)

    Miller, R. L.; Slingo, A.; Barnard, J. C.; Kassianov, E.

    2009-07-01

    Over much of the world, heating of the surface by sunlight is balanced predominately by evaporative cooling. However, at the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) in Niamey, Niger, evaporation makes a significant contribution to the surface energy balance only at the height of the rainy season, when precipitation has replenished the reservoir of soil moisture. The AMF was placed at Niamey from late 2005 to early 2007 to provide measurements of surface fluxes in coordination with geostationary satellite retrievals of radiative fluxes at the top of the atmosphere, as part of the RADAGAST experiment to calculate atmospheric radiative divergence. We use observations at the mobile facility to investigate how the surface adjusts to radiative forcing throughout the year. The surface response to solar heating varies with changes in atmospheric water vapor associated with the seasonal reversal of the West African monsoon, which modulates the greenhouse effect and the ability of the surface to radiate thermal energy directly to space. During the dry season, sunlight is balanced mainly by longwave radiation and the turbulent flux of sensible heat. The ability of longwave radiation to cool the surface drops after the onset of southwesterly surface winds at Niamey, when moist, oceanic air flows onshore, increasing local column moisture and atmospheric opacity. Following the onset of southwesterly flow, evaporation remains limited by the supply of moisture from precipitation. By the height of the rainy season, however, sufficient precipitation has accumulated that evaporation is controlled by incident sunlight, and radiative forcing of the surface is balanced comparably by the latent, sensible, and longwave fluxes. Evaporation increases with the leaf area index, suggesting that plants are a significant source of atmospheric moisture and may tap moisture stored beneath the surface that accumulated during a previous rainy season. Surface radiative forcing

  8. Nano Sensing and Energy Conversion Using Surface Plasmon Resonance (SPR

    Directory of Open Access Journals (Sweden)

    Iltai (Isaac Kim

    2015-07-01

    Full Text Available Nanophotonic technique has been attracting much attention in applications of nano-bio-chemical sensing and energy conversion of solar energy harvesting and enhanced energy transfer. One approach for nano-bio-chemical sensing is surface plasmon resonance (SPR imaging, which can detect the material properties, such as density, ion concentration, temperature, and effective refractive index in high sensitivity, label-free, and real-time under ambient conditions. Recent study shows that SPR can successfully detect the concentration variation of nanofluids during evaporation-induced self-assembly process. Spoof surface plasmon resonance based on multilayer metallo-dielectric hyperbolic metamaterials demonstrate SPR dispersion control, which can be combined with SPR imaging, to characterize high refractive index materials because of its exotic optical properties. Furthermore, nano-biophotonics could enable innovative energy conversion such as the increase of absorption and emission efficiency and the perfect absorption. Localized SPR using metal nanoparticles show highly enhanced absorption in solar energy harvesting. Three-dimensional hyperbolic metamaterial cavity nanostructure shows enhanced spontaneous emission. Recently ultrathin film perfect absorber is demonstrated with the film thickness is as low as ~1/50th of the operating wavelength using epsilon-near-zero (ENZ phenomena at the wavelength close to SPR. It is expected to provide a breakthrough in sensing and energy conversion applications using the exotic optical properties based on the nanophotonic technique.

  9. Estimation of surface impedance using different types of microphone arrays

    DEFF Research Database (Denmark)

    Richard, Antoine Philippe André; Fernandez Grande, Efren; Brunskog, Jonas

    2017-01-01

    This study investigates microphone array methods to measure the angle dependent surface impedance of acoustic materials. The methods are based on the reconstruction of the sound field on the surface of the material, using a wave expansion formulation. The reconstruction of both the pressure...... and the particle velocity leads to an estimation of the surface impedance for a given angle of incidence. A porous type absorber sample is tested experimentally in anechoic conditions for different array geometries, sample sizes, incidence angles, and distances between the array and sample. In particular......, the performances of a rigid spherical array and a double layer planar array are examined. The use of sparse array processing methods and conventional regulariation approaches are studied. In addition, the influence of the size of the sample on the surface impedance estimation is investigated using both...

  10. Modification of the surface energy in isovalent nano-oxides prepared by chemical synthesis

    International Nuclear Information System (INIS)

    Miagava, J.; Gouvea, D.

    2011-01-01

    The phase stability of the nano-oxides depends on the bulk energy but it also depends on the surface energy. The difference of surface energy of the rutile and anatase phases result in a change of phase stability: TiO_2 without additives is stable as anatase when particles have nanometric size and a high specific surface area whereas rutile is stable when particles are larger. But this stability can be modified through the use of additives. Different studies demonstrate that additives segregate on the particle surface modifying the surface energy. In this work (1-X)TiO_2-XSnO_2 powders were synthesized by the polymeric precursor method with concentrations of 0 ≤ X ≤ 1. The specific surface area measurements demonstrate that the modification of the composition change the specific surface areas and it reaches a maximum at X = 0.005. The Raman spectroscopy demonstrates that a modification on the stability of the TiO_2 polymorphs occurs and the phase rutile is stabilized when SnO_2 is added to the nano powders.(author)

  11. Batteries for Efficient Energy Extraction from a Water Salinity Difference

    KAUST Repository

    La Mantia, Fabio; Pasta, Mauro; Deshazer, Heather D.; Logan, Bruce E.; Cui, Yi

    2011-01-01

    The salinity difference between seawater and river water is a renewable source of enormous entropic energy, but extracting it efficiently as a form of useful energy remains a challenge. Here we demonstrate a device called "mixing entropy battery

  12. High resolution electron energy loss spectroscopy of clean and hydrogen covered Si(001) surfaces: first principles calculations.

    Science.gov (United States)

    Patterson, C H

    2012-09-07

    Surface phonons, conductivities, and loss functions are calculated for reconstructed (2×1), p(2×2) and c(4×2) clean Si(001) surfaces, and (2×1) H and D covered Si(001) surfaces. Surface conductivities perpendicular to the surface are significantly smaller than conductivities parallel to the surface. The surface loss function is compared to high resolution electron energy loss measurements. There is good agreement between calculated loss functions and experiment for H and D covered surfaces. However, agreement between experimental data from different groups and between theory and experiment is poor for clean Si(001) surfaces. Formalisms for calculating electron energy loss spectra are reviewed and the mechanism of electron energy losses to surface vibrations is discussed.

  13. Construction of diabatic energy surfaces for LiFH with artificial neural networks

    Science.gov (United States)

    Guan, Yafu; Fu, Bina; Zhang, Dong H.

    2017-12-01

    A new set of diabatic potential energy surfaces (PESs) for LiFH is constructed with artificial neural networks (NNs). The adiabatic PESs of the ground state and the first excited state are directly fitted with NNs. Meanwhile, the adiabatic-to-diabatic transformation (ADT) angles (mixing angles) are obtained by simultaneously fitting energy difference and interstate coupling gradients. No prior assumptions of the functional form of ADT angles are used before fitting, and the ab initio data including energy difference and interstate coupling gradients are well reproduced. Converged dynamical results show remarkable differences between adiabatic and diabatic PESs, which suggests the significance of non-adiabatic processes.

  14. Comparison of Degrees of Potential-Energy-Surface Anharmonicity for Complexes and Clusters with Hydrogen Bonds

    Science.gov (United States)

    Kozlovskaya, E. N.; Doroshenko, I. Yu.; Pogorelov, V. E.; Vaskivskyi, Ye. V.; Pitsevich, G. A.

    2018-01-01

    Previously calculated multidimensional potential-energy surfaces of the MeOH monomer and dimer, water dimer, malonaldehyde, formic acid dimer, free pyridine-N-oxide/trichloroacetic acid complex, and protonated water dimer were analyzed. The corresponding harmonic potential-energy surfaces near the global minima were constructed for series of clusters and complexes with hydrogen bonds of different strengths based on the behavior of the calculated multidimensional potential-energy surfaces. This enabled the introduction of an obvious anharmonicity parameter for the calculated potential-energy surfaces. The anharmonicity parameter was analyzed as functions of the size of the analyzed area near the energy minimum, the number of points over which energies were compared, and the dimensionality of the solved vibrational problem. Anharmonicity parameters for potential-energy surfaces in complexes with strong, medium, and weak H-bonds were calculated under identical conditions. The obtained anharmonicity parameters were compared with the corresponding diagonal anharmonicity constants for stretching vibrations of the bridging protons and the lengths of the hydrogen bridges.

  15. Surface energy of amorphous carbon films containing iron

    International Nuclear Information System (INIS)

    Chen, J. S.; Lau, S. P.; Tay, B. K.; Chen, G. Y.; Sun, Z.; Tan, Y. Y.; Tan, G.; Chai, J. W.

    2001-01-01

    Iron containing diamond-like amorphous carbon (a-C:Fe) films were deposited by filtered cathodic vacuum arc technique. The influences of Fe content and substrate bias on the surface energy of the films were investigated. The surface energy of a-C:Fe films was determined by the contact angle measurement. Atomic force microscopy, Raman spectroscopy, and x-ray induced photoelectron spectroscopy were employed to analyze the origin of the variation of surface energy with various Fe content and substrate bias. It is found that the contact angle for water increases significantly after incorporating Fe into the films and the films become hydrophobic. The roughness of these films has no effect on the contact angle. The surface energy is reduced from 42.8 to 25 dyne/cm after incorporating Fe into the a-C film (10% Fe in the target), which is due to the reduction of both dispersive and polar component. The reduction in dispersive component is ascribed to the decrease of atomic density of the a-C:Fe films due to the increase in sp 2 bonded carbon. When sp 2 content increases to some extent, the atomic density remains constant and hence dispersive component does not change. The absorption of oxygen on the surface plays an important role in the reduction of the polar component for the a-C:Fe films. It is proposed that such network as (C n - O - Fe) - O - (Fe - O - C n ) may be formed and responsible for the reduction of polar component. [copyright] 2001 American Institute of Physics

  16. Low energy pion detection by a silicon surface barrier telescope

    International Nuclear Information System (INIS)

    Sealock, R.M.; Caplan, H.S.; Leung, M.K.

    1978-01-01

    Four telescopes of three (2-ΔE, 1-E) silicon surface barrier detectors each, mounted in the focal plane of a magnetic spectrometer, have been used to detect positive pions in the energy range from 4.7-17.9 MeV and negative pions from 14.1-17.9 MeV. Positive pions from 4.7-12.7 MeV were stopped in the third detector while positive and negative pions from 14.1-17.9 MeV were detected in transmission. For energies greater than 7.4 MeV aluminum moderators were placed in front of the first detector to degrade the pion energy. Energy spectra show well resolved pion peaks with extremely low background. Double differential cross sections for the 12 C(e,π + ) 12 B,e' reaction have been measured. (Auth.)

  17. Harvesting electrostatic energy using super-hydrophobic surfaces

    Science.gov (United States)

    Pociecha, Dominik; Zylka, Pawel

    2016-11-01

    Almost all environments are now being extensively populated by miniaturized, nano-powered electronic sensor devices communicated together through wireless sensor networks building Internet of Things (IoT). Various energy harvesting techniques are being more and more frequently proposed for battery-less powering of such remote, unattended, implantable or wearable sensors or other low-power electronic gadgets. Energy harvesting relays on extracting energy from the ambient sources readily accessible at the sensor location and converting it into electrical power. The paper exploits possibility of generating electric energy safely accessible for nano-power electronics using tribo-electric and electrostatic induction phenomena displayed at super-hydrophobic surfaces impinged by water droplets. Mechanism of such interaction is discussed and illustrated by experimental results.

  18. Scaling of surface energy fluxes using remotely sensed data

    Science.gov (United States)

    French, Andrew Nichols

    Accurate estimates of evapotranspiration (ET) across multiple terrains would greatly ease challenges faced by hydrologists, climate modelers, and agronomists as they attempt to apply theoretical models to real-world situations. One ET estimation approach uses an energy balance model to interpret a combination of meteorological observations taken at the surface and data captured by remote sensors. However, results of this approach have not been accurate because of poor understanding of the relationship between surface energy flux and land cover heterogeneity, combined with limits in available resolution of remote sensors. The purpose of this study was to determine how land cover and image resolution affect ET estimates. Using remotely sensed data collected over El Reno, Oklahoma, during four days in June and July 1997, scale effects on the estimation of spatially distributed ET were investigated. Instantaneous estimates of latent and sensible heat flux were calculated using a two-source surface energy balance model driven by thermal infrared, visible-near infrared, and meteorological data. The heat flux estimates were verified by comparison to independent eddy-covariance observations. Outcomes of observations taken at coarser resolutions were simulated by aggregating remote sensor data and estimated surface energy balance components from the finest sensor resolution (12 meter) to hypothetical resolutions as coarse as one kilometer. Estimated surface energy flux components were found to be significantly dependent on observation scale. For example, average evaporative fraction varied from 0.79, using 12-m resolution data, to 0.93, using 1-km resolution data. Resolution effects upon flux estimates were related to a measure of landscape heterogeneity known as operational scale, reflecting the size of dominant landscape features. Energy flux estimates based on data at resolutions less than 100 m and much greater than 400 m showed a scale-dependent bias. But estimates

  19. Adsorption and enzymatic cleavage of osteopontin at interfaces with different surface chemistries

    DEFF Research Database (Denmark)

    Malmström, Jenny; Shipovskov, Stepan; Christensen, Brian

    2009-01-01

    (methyl-, carboxylic-, and amine-terminated alkanethiol self-assembled monolayers and bare gold) have been studied utilizing a combination of the quartz crystal microbalance with dissipation and surface plasmon resonance. Full length bovine milk osteopontin was used which is well characterized...... at the polar surfaces with the highest level of hydration being observed at the gold surface. The energy dissipation of these thin films (as measured by the DeltaD/DeltaF value) was altered at the different surface chemistries and interestingly a higher dissipation correlated with a higher density. Thrombin...... with respect to post-translational modifications. Osteopontin adsorbed at all the surfaces formed thin (approximately 2-5 nm) hydrated layers with the highest amount of protein and the highest density layers observed at the hydrophobic surface. Less protein and a higher level of hydration was observed...

  20. Behavior of Rydberg atoms at surfaces: energy level shifts and ionization

    Energy Technology Data Exchange (ETDEWEB)

    Dunning, F.B. E-mail: fbd@rice.edu; Dunham, H.R.; Oubre, C.; Nordlander, P

    2003-04-01

    The ionization of xenon atoms excited to the extreme red and blue states in high-lying Xe(n) Stark manifolds at a metal surface is investigated. The data show that, despite their very different initial spatial characteristics, the extreme members of a given Stark manifold ionize at similar atom/surface separations. This is explained, with the aid of complex scaling calculations, in terms of the strong perturbations in the energies and structure of the atomic states induced by the presence of the surface which lead to avoided crossings between neighboring levels as the surface is approached.

  1. Behavior of Rydberg atoms at surfaces: energy level shifts and ionization

    CERN Document Server

    Dunning, F B; Oubre, C D; Nordlander, P

    2003-01-01

    The ionization of xenon atoms excited to the extreme red and blue states in high-lying Xe(n) Stark manifolds at a metal surface is investigated. The data show that, despite their very different initial spatial characteristics, the extreme members of a given Stark manifold ionize at similar atom/surface separations. This is explained, with the aid of complex scaling calculations, in terms of the strong perturbations in the energies and structure of the atomic states induced by the presence of the surface which lead to avoided crossings between neighboring levels as the surface is approached.

  2. Surface modifications of polypropylene by high energy carbon ions

    International Nuclear Information System (INIS)

    Saha, A.; Chakraborty, V.; Dutta, R.K.; Chintalapudi, S.N.

    2000-01-01

    Polypropylene was irradiated with 12 C ions of 3.6 and 5.4 MeV energies using 3 MV tandem accelerator. The surface modification was investigated by Scanning Electron Microscopy (SEM). Optical changes were monitored by UV-VIS and FTIR spectroscopy. At the lowest ion fluence, only blister formation of various sizes (1-6 μm) was observed. Polymer when irradiated at a fluence of 1x10 14 ions/cm 2 exhibited a network structure. A comparative study on dose dependence of surface and bulk modification has been described. (author)

  3. Silver nanoprisms self-assembly on differently functionalized silica surface

    International Nuclear Information System (INIS)

    Pilipavicius, J; Chodosovskaja, A; Beganskiene, A; Kareiva, A

    2015-01-01

    In this work colloidal silica/silver nanoprisms (NPRs) composite coatings were made. Firstly colloidal silica sols were synthesized by sol-gel method and produced coatings on glass by dip-coating technique. Next coatings were silanized by (3-Aminopropyl)triethoxysilane (APTES), N-[3-(Trimethoxysilyl)propyl]ethylenediamine (AEAPTMS), (3- Mercaptopropyl)trimethoxysilane (MPTMS). Silver NPRs where synthesized via seed-mediated method and high yield of 94±15 nm average edge length silver NPRs were obtained with surface plasmon resonance peak at 921 nm. Silica-Silver NPRs composite coatings obtained by selfassembly on silica coated-functionalized surface. In order to find the most appropriate silanization way for Silver NPRs self-assembly, the composite coatings were characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), water contact angle (CA) and surface free energy (SFE) methods. Results have showed that surface functionalization is necessary to achieve self-assembled Ag NPRs layer. MPTMS silanized coatings resulted sparse distribution of Ag NPRs. Most homogeneous, even distribution composite coatings obtained on APTES functionalized silica coatings, while AEAPTMS induced strong aggregation of Silver NPRs

  4. Modification of high density polyethylene by gold implantation using different ion energies

    Energy Technology Data Exchange (ETDEWEB)

    Nenadović, M.; Potočnik, J. [INS Vinca, Laboratory of Atomic Physics, University of Belgrade, Mike Alasa 12–14, 11001 Belgrade (Serbia); Mitrić, M. [INS Vinca, Condensed Matter Physics Laboratory, University of Belgrade, Mike Alasa 12–14, 11001 Belgrade (Serbia); Štrbac, S. [ICTM Institute of Electrochemistry, University of Belgrade, Njegoseva 12, 11001 Belgrade (Serbia); Rakočević, Z., E-mail: zlatkora@vinca.rs [INS Vinca, Laboratory of Atomic Physics, University of Belgrade, Mike Alasa 12–14, 11001 Belgrade (Serbia)

    2013-11-01

    High density polyethylene (HDPE) samples were modified by Au{sup +} ion implantation at a dose of 5 × 10{sup 15} ions cm{sup −2}, using energies of 50, 100, 150 and 200 keV. The existence of implanted gold in the near-surface region of HDPE samples was confirmed by X-ray diffraction analysis. Surface roughness and Power Spectral Density analyses based on Atomic Force Microscopy (AFM) images of the surface topography revealed that the mechanism of HDPE modification during gold ion implantation depended on the energy of gold ions. Histograms obtained from phase AFM images indicated a qualitative change in the chemical composition of the surface during implantation with gold ions with different energies. Depth profiles obtained experimentally from cross-sectional Force Modulation Microscopy images and ones obtained from a theoretical simulation are in agreement for gold ions energies lower than 100 keV. The deviation that was observed for higher energies of the gold ions is explained by carbon precipitation in the near surface region of the HDPE, which prevented the penetration of gold ions further into the depth of the sample. - Highlights: • HDPE was implanted by Au{sup +} ions using energies of 50, 100, 150 and 200 keV. • Surface composition was analyzed from phase AFM images. • FMM depth profiles are in agreement with theoretical ones for energies up to 100 keV. • A deviation is observed for higher gold ion energies.

  5. Modification of high density polyethylene by gold implantation using different ion energies

    International Nuclear Information System (INIS)

    Nenadović, M.; Potočnik, J.; Mitrić, M.; Štrbac, S.; Rakočević, Z.

    2013-01-01

    High density polyethylene (HDPE) samples were modified by Au + ion implantation at a dose of 5 × 10 15 ions cm −2 , using energies of 50, 100, 150 and 200 keV. The existence of implanted gold in the near-surface region of HDPE samples was confirmed by X-ray diffraction analysis. Surface roughness and Power Spectral Density analyses based on Atomic Force Microscopy (AFM) images of the surface topography revealed that the mechanism of HDPE modification during gold ion implantation depended on the energy of gold ions. Histograms obtained from phase AFM images indicated a qualitative change in the chemical composition of the surface during implantation with gold ions with different energies. Depth profiles obtained experimentally from cross-sectional Force Modulation Microscopy images and ones obtained from a theoretical simulation are in agreement for gold ions energies lower than 100 keV. The deviation that was observed for higher energies of the gold ions is explained by carbon precipitation in the near surface region of the HDPE, which prevented the penetration of gold ions further into the depth of the sample. - Highlights: • HDPE was implanted by Au + ions using energies of 50, 100, 150 and 200 keV. • Surface composition was analyzed from phase AFM images. • FMM depth profiles are in agreement with theoretical ones for energies up to 100 keV. • A deviation is observed for higher gold ion energies

  6. The interaction of low energy ion beams with surfaces

    International Nuclear Information System (INIS)

    Carter, G.; Armour, D.G.

    1981-01-01

    Four of the most important physical processes which occur during ion plating and allied techniques (1) ion-induced (and energetic-atom-induced) desorption of adsorbed impurities from the substrate surface, (2) ion penetration and entrapment in the substrate and coating, (3) ion-induced sputtering of substrate and coating atoms and (4) recoil displacement of substrate and coating atoms leading to their intermixing. The ion and energetic atom energy range of importance is from thermal energies to the order of 1keV. Current understanding of these processes, supported by discussion of available experimental data, is reviewed. (Auth.)

  7. Capillary surfaces in a wedge: Differing contact angles

    Science.gov (United States)

    Concus, Paul; Finn, Robert

    1994-01-01

    The possible zero-gravity equilibrium configurations of capillary surfaces u(x, y) in cylindrical containers whose sections are (wedge) domains with corners are investigated mathematically, for the case in which the contact angles on the two sides of the wedge may differ. In such a situation the behavior can depart in significant qualitative ways from that for which the contact angles on the two sides are the same. Conditions are described under which such qualitative changes must occur. Numerically computed surfaces are depicted to indicate the behavior.

  8. Ab initio surface core-level shifts and surface segregation energies

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Johansson, Börje

    1993-01-01

    We have calculated the surface core-level energy shifts of the 4d and 5d transition metals by means of local-density theory and a Green’s-function technique based on the linear muffin-tin orbitals method. Final-state effects are included by treating the core-ionized atom as an impurity located in...

  9. Electronic structure, molecular bonding and potential energy surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ruedenberg, K. [Ames Laboratory, IA (United States)

    1993-12-01

    By virtue of the universal validity of the generalized Born-Oppenheimer separation, potential energy surfaces (PES`) represent the central conceptual as well as quantitative entities of chemical physics and provide the basis for the understanding of most physicochemical phenomena in many diverse fields. The research in this group deals with the elucidation of general properties of PES` as well as with the quantitative determination of PES` for concrete systems, in particular pertaining to reactions involving carbon, oxygen, nitrogen and hydrogen molecules.

  10. Fowler's approximation for the surface tension and surface energy of Lennard-Jones fluids revisited

    Energy Technology Data Exchange (ETDEWEB)

    Mulero, A [Departamento de Fisica, Universidad de Extremadura, 06071-Badajoz (Spain); Galan, C [Departamento de Fisica, Universidad de Extremadura, 06071-Badajoz (Spain); Cuadros, F [Departamento de Fisica, Universidad de Extremadura, 06071-Badajoz (Spain)

    2003-04-16

    We present a detailed study of the validity of Fowler's approximation for calculating the surface tension and the surface energy of Lennard-Jones fluids. To do so, we consider three different explicit analytical expressions for the radial distribution function (RDF), including one proposed by our research group, together with very accurate expressions for the liquid and vapour densities, also proposed by our group. The calculation of the surface tension from the direct correlation function using both the Percus-Yevick and the hypernetted-chain approximations is also considered. Finally, our results are compared with those obtained by other authors by computer simulations or through relevant theoretical approximations. In particular, we consider the analytical expression proposed by Kalikmanov and Hofmans (1994 J. Phys.: Condens. Matter 6 2207-14) for the surface tension. Our results indicate that the values for the surface energy in Fowler's approximation obtained by other authors are adequate, and can be calculated from the RDF models. For the surface tension, however, the values considered as valid in previous works seem to be incorrect. The correct values can be obtained from our model for the RDF or from the Kalikmanov and Hofmans expression with suitable inputs.

  11. Effects of different ground surface on rye habit and yield

    International Nuclear Information System (INIS)

    Doroszewski, A.

    1995-01-01

    Rye was sown in pots imbeded into the ground, in non-competitive conditions. Plot differed only with kinds of ground surfaces (grass, bare soil) which affected the spectral composition of reflected sunlight. Plants growing on the ground covered with grass received more radiation in the range of far red than plants growing on bare soil. The plants from both plots reacted differently to the environmental conditions by creating different habits. Main shoots of rye growing in the neighbourhood of grass had been much taller than the rye growing on the bare soil; its internodes were longer and its heads heavier and heads had more grain

  12. Surface roughness of orthodontic band cements with different compositions

    Directory of Open Access Journals (Sweden)

    Françoise Hélène van de Sande

    2011-06-01

    Full Text Available OBJECTIVES: The present study evaluated comparatively the surface roughness of four orthodontic band cements after storage in various solutions. MATERIAL AND METHODS: Eight standardized cylinders were made from 4 materials: zinc phosphate cement (ZP, compomer (C, resin-modified glass ionomer cement (RMGIC and resin cement (RC. Specimens were stored for 24 h in deionized water and immersed in saline (pH 7.0 or 0.1 M lactic acid solution (pH 4.0 for 15 days. Surface roughness readings were taken with a profilometer (Surfcorder SE1200 before and after the storage period. Data were analyzed by two-way ANOVA and Tukey's test (comparison among cements and storage solutions or paired t-test (comparison before and after the storage period at 5% significance level. RESULTS: The values for average surface roughness were statistically different (pRMGIC>C>R (p0.05. Compared to the current threshold (0.2 µm related to biofilm accumulation, both RC and C remained below the threshold, even after acidic challenge by immersion in lactic acid solution. CONCLUSIONS: Storage time and immersion in lactic acid solution increased the surface roughness of the majority of the tested cements. RC presented the smoothest surface and it was not influenced by storage conditions.

  13. Surface and sliding wear behaviour of different coatings and steels

    Energy Technology Data Exchange (ETDEWEB)

    Vera-Cardenas, E.E. [Universidad Politecnica de Pachuca, Zempoala, Hidalgo (Mexico)]. E-mail: evera@upp.edu.mx; Vite-Torres, M. [Instituto Politecnico Nacional, Mexico D.F. (Mexico)]. E-mail: drmanulvite9@hotmail.com; Lewis, R. [University of Sheffield (United Kingdom)]. E-mail: roger.lewis@sheffield.ac.uk

    2012-01-15

    In this work, the sliding wear behaviour of the coatings TiN, CrN and WC/C applied on steel substrates was studied using a reciprocating wear test machine. All tests were carried out in dry conditions, at room temperature (20-23 degrees Celsius and 45% - 50% relative humidity). The average sliding velocity was 0.08 m/s and an amplitude of 2 mm was used. The applied loads were 11.76 N (Po = 1.74 GPa) and 7.84 N (Po = 1.52 GPa). Optical microscopy was used to observe the characteristics of wear scars and spalls and possible causes of their formation. The variation of the friction coefficient against the number of cycles was obtained. This was used to determine more precisely the time (number of cycles) where the coating presented the first signs of wear, in addition Energy Dispersive X-ray analysis (EDS) was performed, as well as Scanning Electron Microscopy (SEM) and hardness tests on the wear traces, which reinforced the previous observations. Thus it was possible to know the wear life of different coatings and possible causes of variation. Increasing the load was an important factor in the variation of wear life results. But it is also important to consider other factors such as surface roughness and thickness of coatings. [Spanish] En este trabajo se estudio el comportamiento en desgaste por deslizamiento de los recubrimientos de TiN, CrN y WC/C aplicados sobre sustratos de acero. Las pruebas se realizaron con una maquina reciprocante en condiciones secas a temperatura ambiente (20-23 grados centigrados y 45% - 50% de humedad relativa). Se empleo una velocidad promedio de 0.08 m/s y una amplitud de 2 mm. Las cargas aplicadas fueron de 11.76N (Po = 1.74 GPa) y de 7.84 N (Po = 1.52 GPa). Se realizo microscopia optica para observar las caracteristicas de las zonas de desgaste y sus posibles causas de formacion. Se obtuvo graficamente la variacion del coeficiente de friccion con el numero de ciclos. Estos datos se emplearon para determinar con mayor precision el

  14. Study on the energy performance of glazing surfaces

    Directory of Open Access Journals (Sweden)

    Ligia MOGA

    2014-12-01

    Full Text Available A proper thermal design of the building envelope represents an important factor for the energy economics. Glazing surfaces represent one of the important elements in the hygrothermal design activity of a building envelope. The window’s thermal performance has also a strong influence on the thermal performance of the opaque area of the wall. This fact imposed the research of the real interaction, of cooperation and of mutual influences of the characteristics between the two components of the wall of the building envelope, respectively the opaque and the glazing area. Optimal constructive details for the opaque and glazing area of the wall need to be properly designed in order to achieve the required thermal and energy performances imposed for new types of buildings, e.g. passive houses, zero energy buildings.

  15. Active surface model improvement by energy function optimization for 3D segmentation.

    Science.gov (United States)

    Azimifar, Zohreh; Mohaddesi, Mahsa

    2015-04-01

    This paper proposes an optimized and efficient active surface model by improving the energy functions, searching method, neighborhood definition and resampling criterion. Extracting an accurate surface of the desired object from a number of 3D images using active surface and deformable models plays an important role in computer vision especially medical image processing. Different powerful segmentation algorithms have been suggested to address the limitations associated with the model initialization, poor convergence to surface concavities and slow convergence rate. This paper proposes a method to improve one of the strongest and recent segmentation algorithms, namely the Decoupled Active Surface (DAS) method. We consider a gradient of wavelet edge extracted image and local phase coherence as external energy to extract more information from images and we use curvature integral as internal energy to focus on high curvature region extraction. Similarly, we use resampling of points and a line search for point selection to improve the accuracy of the algorithm. We further employ an estimation of the desired object as an initialization for the active surface model. A number of tests and experiments have been done and the results show the improvements with regards to the extracted surface accuracy and computational time of the presented algorithm compared with the best and recent active surface models. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. On the mechanics of continua with boundary energies and growing surfaces

    Science.gov (United States)

    Papastavrou, Areti; Steinmann, Paul; Kuhl, Ellen

    2013-06-01

    Many biological systems are coated by thin films for protection, selective absorption, or transmembrane transport. A typical example is the mucous membrane covering the airways, the esophagus, and the intestine. Biological surfaces typically display a distinct mechanical behavior from the bulk; in particular, they may grow at different rates. Growth, morphological instabilities, and buckling of biological surfaces have been studied intensely by approximating the surface as a layer of finite thickness; however, growth has never been attributed to the surface itself. Here, we establish a theory of continua with boundary energies and growing surfaces of zero thickness in which the surface is equipped with its own potential energy and is allowed to grow independently of the bulk. In complete analogy to the kinematic equations, the balance equations, and the constitutive equations of a growing solid body, we derive the governing equations for a growing surface. We illustrate their spatial discretization using the finite element method, and discuss their consistent algorithmic linearization. To demonstrate the conceptual differences between volume and surface growth, we simulate the constrained growth of the inner layer of a cylindrical tube. Our novel approach toward continua with growing surfaces is capable of predicting extreme growth of the inner cylindrical surface, which more than doubles its initial area. The underlying algorithmic framework is robust and stable; it allows to predict morphological changes due to surface growth during the onset of buckling and beyond. The modeling of surface growth has immediate biomedical applications in the diagnosis and treatment of asthma, gastritis, obstructive sleep apnoea, and tumor invasion. Beyond biomedical applications, the scientific understanding of growth-induced morphological instabilities and surface wrinkling has important implications in material sciences, manufacturing, and microfabrication, with applications in

  17. Clay mineralogy in different geomorphic surfaces in sugarcane areas

    Science.gov (United States)

    Camargo, L.; Marques, J., Jr.

    2012-04-01

    The crystallization of the oxides and hydroxides of iron and aluminum and kaolinite of clay fraction is the result of pedogenetic processes controlled by the relief. These minerals have influence on the physical and chemical attributes of soil and exhibit spatial dependence. The pattern of spatial distribution is influenced by forms of relief as the geomorphic surfaces. In this sense, the studies aimed at understanding the relationship between relief and the distribution pattern of the clay fraction attributes contribute to the delineation of specific areas of management in the field. The objective of this study was to evaluate the spatial distribution of oxides and hydroxides of iron and aluminum and kaolinite of clay fraction and its relationship with the physical and chemical attributes in different geomorphic surfaces. Soil samples were collected in a transect each 25 m (100 samples) and in the sides of the same (200 samples) as well as an area of 500 ha (1 sample each six hectare). Geomorphic surfaces (GS) in the transect were mapped in detail to support mapping the entire area. The soil samples were taken to the laboratory for chemical, physical, and mineralogical analysis, and the pattern of spatial distribution of soil attributes was obtained by statistics and geostatistics. The GS I is considered the oldest surface of the study area, with depositional character, and a slope ranging from 0 to 4%. GS II and III are considered to be eroded, and the surface II plan a gentle slope that extends from the edge of the surface until the beginning of I and III. The crystallographic characteristics of the oxides and hydroxides of iron and aluminum and kaolinite showed spatial dependence and the distribution pattern corresponding to the limits present of the GS in the field. Surfaces I and II showed the best environments to the degree of crystallinity of hematite and the surface III to the greatest degree of crystallinity of goethite agreeing to the pedoenvironment

  18. Micro reflectance difference techniques: Optical probes for surface exploration

    Energy Technology Data Exchange (ETDEWEB)

    Lastras-Martinez, L.F.; Del Pozo-Zamudio, O.; Herrera-Jasso, R.; Ulloa-Castillo, N.A.; Balderas-Navarro, R.E.; Ortega-Gallegos, J.; Lastras-Martinez, A. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, 78000 San Luis Potosi, S.L.P. (Mexico)

    2012-06-15

    Micro reflectance difference spectroscopy ({mu}-RDS) is a promising tool for the in-situ and ex-situ characterization of semiconductors surfaces and interfaces. We discuss and compare two different approaches used to measure {mu}-RD spectra. One is based on a charge-coupled device (CCD) camera, while the other uses a laser and a XY translation stage. To show the performance of these systems, we have measured surface optical anisotropies of GaSb(001) sample on which anisotropic strains have been generated by preferential mechanical polishing along [110] and [1 anti 10] directions. The spectrometers are complementary and the selection of one of them depends on the sample to be investigated and on experimental conditions. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. A dielectric matrix calculation of the surface-plasmon energy for the silicon (100) surface

    International Nuclear Information System (INIS)

    Forsyth, A.J.; Smith, A.E.; Josefsson, T.W.

    1996-01-01

    Full text: As an extension of previous work, we present preliminary calculations for the dielectric properties of the silicon (100) surface. In particular, the |q|→0 and |q|=2π/a(1,0,0) surface loss function, and corresponding surface plasmon energies have been calculated within a simple model for the silicon surface. The results have been obtained from the Adler and Wiser dielectric matrix (DM). The bandstructure used for the calculation was based on the highly successful empirical pseudopotential method of Cohen and Chelikovsky. We have used a 59 plane wave basis for the bandstructure, and have chosen a DM size of 59 x 59. Results are compared and contrasted with volume plasmon calculations, free electron calculations and experiment

  20. Perception of the energy question in different regions of France

    International Nuclear Information System (INIS)

    Fouque, B.; Villaret, J.M.

    1982-01-01

    The authors first outline the main variables which account for regional differences in the perception of the energy question, and go on to discuss these differences and the factors underlying them [fr

  1. Xe ion beam induced rippled structures on differently oriented single-crystalline Si surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hanisch, Antje; Grenzer, Joerg; Facsko, Stefan [Forschungszentrum Dresden-Rossendorf, Institut fuer Ionenstrahlphysik und Materialforschung, PO Box 510119, 01314 Dresden (Germany); Biermanns, Andreas; Pietsch, Ullrich, E-mail: A.Hanisch@fzd.d [Universitaet Siegen, Festkoerperphysik, 57068 Siegen (Germany)

    2010-03-24

    We report on Xe{sup +} induced ripple formation at medium energy on single-crystalline silicon surfaces of different orientations using substrates with an intentional miscut from the [0 0 1] direction and a [1 1 1] oriented wafer. The ion beam incidence angle with respect to the surface normal was kept fixed at 65{sup 0} and the ion beam projection was parallel or perpendicular to the [1 1 0] direction. By a combination of atomic force microscopy, x-ray diffraction and high-resolution transmission electron microscopy we found that the features of the surface and subsurface rippled structures such as ripple wavelength and amplitude and the degree of order do not depend on the surface orientation as assumed in recent models of pattern formation for semiconductor surfaces. (fast track communication)

  2. Effect of Groove Surface Texture on Tribological Characteristics and Energy Consumption under High Temperature Friction.

    Science.gov (United States)

    Wu, Wei; Chen, Guiming; Fan, Boxuan; Liu, Jianyou

    2016-01-01

    Energy consumption and tribological properties could be improved by proper design of surface texture in friction. However, some literature focused on investigating their performance under high temperature. In the study, different groove surface textures were fabricated on steels by a laser machine, and their tribological behaviors were experimentally studied with the employment of the friction and wear tester under distinct high temperature and other working conditions. The friction coefficient was recorded, and wear performance were characterized by double light interference microscope, scanning electron microscope (SEM) and x-ray energy dispersive spectrometry (EDS). Then, the performances of energy consumptions were carefully estimated. Results showed that friction coefficient, wear, and energy consumption could almost all be reduced by most textures under high temperature conditions, but to a different extent which depends on the experimental conditions and texture parameters. The main improvement mechanisms were analyzed, such as the hardness change, wear debris storage, thermal stress release and friction induced temperature reduction by the textures. Finally, a scattergram of the relatively reduced ratio of the energy consumption was drawn for different surface textures under four distinctive experimental conditions to illustrate the comprehensive energy consumption improving ability of textures, which was of benefit for the application of texture design.

  3. Surface free energy predominates in cell adhesion to hydroxyapatite through wettability.

    Science.gov (United States)

    Nakamura, Miho; Hori, Naoko; Ando, Hiroshi; Namba, Saki; Toyama, Takeshi; Nishimiya, Nobuyuki; Yamashita, Kimihiro

    2016-05-01

    The initial adhesion of cells to biomaterials is critical in the regulation of subsequent cell behaviors. The purpose of this study was to investigate a mechanism through which the surface wettability of biomaterials can be improved and determine the effects of biomaterial surface characteristics on cellular behaviors. We investigated the surface characteristics of various types of hydroxyapatite after sintering in different atmospheres and examined the effects of various surface characteristics on cell adhesion to study cell-biomaterial interactions. Sintering atmosphere affects the polarization capacity of hydroxyapatite by changing hydroxide ion content and grain size. Compared with hydroxyapatite sintered in air, hydroxyapatite sintered in saturated water vapor had a higher polarization capacity that increased surface free energy and improved wettability, which in turn accelerated cell adhesion. We determined the optimal conditions of hydroxyapatite polarization for the improvement of surface wettability and acceleration of cell adhesion. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Surface energy and surface stress on vicinals by revisiting the Shuttleworth relation

    Science.gov (United States)

    Hecquet, Pascal

    2018-04-01

    In 1998 [Surf. Sci. 412/413, 639 (1998)], we showed that the step stress on vicinals varies as 1/L, L being the distance between steps, while the inter-step interaction energy primarily follows the law as 1/L2 from the well-known Marchenko-Parshin model. In this paper, we give a better understanding of the interaction term of the step stress. The step stress is calculated with respect to the nominal surface stress. Consequently, we calculate the diagonal surface stresses in both the vicinal system (x, y, z) where z is normal to the vicinal and the projected system (x, b, c) where b is normal to the nominal terrace. Moreover, we calculate the surface stresses by using two methods: the first called the 'Zero' method, from the surface pressure forces and the second called the 'One' method, by homogeneously deforming the vicinal in the parallel direction, x or y, and by calculating the surface energy excess proportional to the deformation. By using the 'One' method on the vicinal Cu(0 1 M), we find that the step deformations, due to the applied deformation, vary as 1/L by the same factor for the tensor directions bb and cb, and by twice the same factor for the parallel direction yy. Due to the vanishing of the surface stress normal to the vicinal, the variation of the step stress in the direction yy is better described by using only the step deformation in the same direction. We revisit the Shuttleworth formula, for while the variation of the step stress in the direction xx is the same between the two methods, the variation in the direction yy is higher by 76% for the 'Zero' method with respect to the 'One' method. In addition to the step energy, we confirm that the variation of the step stress must be taken into account for the understanding of the equilibrium of vicinals when they are not deformed.

  5. The nanostructure formation on muscovite mica surface induced by intermediate-energy ions

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, P.; Zhang, HQ., E-mail: zhanghq@lzu.edu.cn; Zhang, Q.; Liu, Z.; Guan, S.; Wang, G.; Zhou, C.; Jia, J.; Lv, X.; Shao, J.; Cui, Y.; Chen, L.; Chen, X., E-mail: chenxm@lzu.edu.cn

    2013-07-15

    Muscovite mica sheets were bombarded by lithium, carbon and oxygen ions in the energy range from several hundred keV to several MeV. The induced surface structures were measured in the air with atomic force microscopy (AFM) in the tapping mode. The hillock-like structure on the mica surface was observed. The height of the hillock increases linearly when the energy loss is above 1.2 keV/nm. The induced structures are similar with the similar electronic stopping powers but different projectiles for muscovite mica.

  6. Treatment of surfaces with low-energy electrons

    Science.gov (United States)

    Frank, L.; Mikmeková, E.; Lejeune, M.

    2017-06-01

    Electron-beam-induced deposition of various materials from suitable precursors has represented an established branch of nanotechnology for more than a decade. A specific alternative is carbon deposition on the basis of hydrocarbons as precursors that has been applied to grow various nanostructures including masks for subsequent technological steps. Our area of study was unintentional electron-beam-induced carbon deposition from spontaneously adsorbed hydrocarbon molecules. This process traditionally constitutes a challenge for scanning electron microscopy practice preventing one from performing any true surface studies outside an ultrahigh vacuum and without in-situ cleaning of samples, and also jeopardising other electron-optical devices such as electron beam lithographs. Here we show that when reducing the energy of irradiating electrons sufficiently, the e-beam-induced deposition can be converted to e-beam-induced release causing desorption of hydrocarbons and ultimate cleaning of surfaces in both an ultrahigh and a standard high vacuum. Using series of experiments with graphene samples, we demonstrate fundamental features of e-beam-induced desorption and present results of checks for possible radiation damage using Raman spectroscopy that led to optimisation of the electron energy for damage-free cleaning. The method of preventing carbon contamination described here paves the way for greatly enhanced surface sensitivity of imaging and substantially reduced demands on vacuum systems for nanotechnological applications.

  7. Relationship between enamel bond fatigue durability and surface free-energy characteristics with universal adhesives.

    Science.gov (United States)

    Nagura, Yuko; Tsujimoto, Akimasa; Barkmeier, Wayne W; Watanabe, Hidehiko; Johnson, William W; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

    2018-04-01

    The relationship between enamel bond fatigue durability and surface free-energy characteristics with universal adhesives was investigated. The initial shear bond strengths and shear fatigue strengths of five universal adhesives to enamel were determined with and without phosphoric acid pre-etching. The surface free-energy characteristics of adhesive-treated enamel with and without pre-etching were also determined. The initial shear bond strength and shear fatigue strength of universal adhesive to pre-etched enamel were higher than those to ground enamel. The initial shear bond strength and shear fatigue strength of universal adhesive to pre-etched enamel were material dependent, unlike those to ground enamel. The surface free-energy of the solid (γ S ) and the hydrogen-bonding force (γSh) of universal adhesive-treated enamel were different depending on the adhesive, regardless of the presence or absence of pre-etching. The bond fatigue durability of universal adhesives was higher to pre-etched enamel than to ground enamel. In addition, the bond fatigue durability to pre-etched enamel was material dependent, unlike that to ground enamel. The surface free-energy characteristics of universal adhesive-treated enamel were influenced by the adhesive type, regardless of the presence or absence of pre-etching. The surface free-energy characteristics of universal adhesive-treated enamel were related to the results of the bond fatigue durability. © 2018 Eur J Oral Sci.

  8. Diabat Interpolation for Polymorph Free-Energy Differences.

    Science.gov (United States)

    Kamat, Kartik; Peters, Baron

    2017-02-02

    Existing methods to compute free-energy differences between polymorphs use harmonic approximations, advanced non-Boltzmann bias sampling techniques, and/or multistage free-energy perturbations. This work demonstrates how Bennett's diabat interpolation method ( J. Comput. Phys. 1976, 22, 245 ) can be combined with energy gaps from lattice-switch Monte Carlo techniques ( Phys. Rev. E 2000, 61, 906 ) to swiftly estimate polymorph free-energy differences. The new method requires only two unbiased molecular dynamics simulations, one for each polymorph. To illustrate the new method, we compute the free-energy difference between face-centered cubic and body-centered cubic polymorphs for a Gaussian core solid. We discuss the justification for parabolic models of the free-energy diabats and similarities to methods that have been used in studies of electron transfer.

  9. Near-surface energy transfers from internal tide beams to smaller vertical scale motions

    Science.gov (United States)

    Chou, S.; Staquet, C.; Carter, G. S.; Luther, D. S.

    2016-02-01

    Mechanical energy capable of causing diapycnal mixing in the ocean is transferred to the internal wave field when barotropic tides pass over underwater topography and generate internal tides. The resulting internal tide energy is confined in vertically limited structures, or beams. As internal tide beams (ITBs) propagate through regions of non-uniform stratification in the upper ocean, wave energy can be scattered through multiple reflections and refractions, be vertically trapped, or transferred to non-tidal frequencies through different nonlinear processes. Various observations have shown that ITBs are no longer detectable in horizontal kinetic energy beyond the first surface reflection. Importantly, this implies that some of the internal tide energy no longer propagates in to the abyssal ocean and consequently will not be available to maintain the density stratification. Using the NHM, a nonlinear and nonhydrostatic model based on the MITgcm, simulations of an ITB propagating up to the sea surface are examined in order to quantify the transformation of ITB energy to other motions. We compare and contrast the transformations enabled by idealized, smoothly-varying stratification with transformations enabled by realistic stratification containing a broad-band vertical wavenumber spectrum of variations. Preliminary two-dimensional results show that scattering due to small-scale structure in realistic stratification profiles from Hawaii can lead to energy being vertically trapped near the surface. Idealized simulations of "locally" generated internal solitary waves are analyzed in terms of energy flux transfers from the ITB to solitary waves, higher harmonics, and mean flow. The amount of internal tide energy which propagates back down after near-surface reflection of the ITB in different environments is quantified.

  10. Batteries for efficient energy extraction from a water salinity difference.

    Science.gov (United States)

    La Mantia, Fabio; Pasta, Mauro; Deshazer, Heather D; Logan, Bruce E; Cui, Yi

    2011-04-13

    The salinity difference between seawater and river water is a renewable source of enormous entropic energy, but extracting it efficiently as a form of useful energy remains a challenge. Here we demonstrate a device called "mixing entropy battery", which can extract and store it as useful electrochemical energy. The battery, containing a Na(2-x)Mn(5)O(10) nanorod electrode, was shown to extract energy from real seawater and river water and can be applied to a variety of salt waters. We demonstrated energy extraction efficiencies of up to 74%. Considering the flow rate of river water into oceans as the limiting factor, the renewable energy production could potentially reach 2 TW, or ∼13% of the current world energy consumption. The mixing entropy battery is simple to fabricate and could contribute significantly to renewable energy in the future.

  11. Batteries for Efficient Energy Extraction from a Water Salinity Difference

    KAUST Repository

    La Mantia, Fabio

    2011-04-13

    The salinity difference between seawater and river water is a renewable source of enormous entropic energy, but extracting it efficiently as a form of useful energy remains a challenge. Here we demonstrate a device called "mixing entropy battery", which can extract and store it as useful electrochemical energy. The battery, containing a Na2-xMn 5O10 nanorod electrode, was shown to extract energy from real seawater and river water and can be applied to a variety of salt waters. We demonstrated energy extraction efficiencies of up to 74%. Considering the flow rate of river water into oceans as the limiting factor, the renewable energy production could potentially reach 2 TW, or ∼13% of the current world energy consumption. The mixing entropy battery is simple to fabricate and could contribute significantly to renewable energy in the future. © 2011 American Chemical Society.

  12. Metadyn View: Fast web-based viewer of free energy surfaces calculated by metadynamics

    Science.gov (United States)

    Hošek, Petr; Spiwok, Vojtěch

    2016-01-01

    Metadynamics is a highly successful enhanced sampling technique for simulation of molecular processes and prediction of their free energy surfaces. An in-depth analysis of data obtained by this method is as important as the simulation itself. Although there are several tools to compute free energy surfaces from metadynamics data, they usually lack user friendliness and a build-in visualization part. Here we introduce Metadyn View as a fast and user friendly viewer of bias potential/free energy surfaces calculated by metadynamics in Plumed package. It is based on modern web technologies including HTML5, JavaScript and Cascade Style Sheets (CSS). It can be used by visiting the web site and uploading a HILLS file. It calculates the bias potential/free energy surface on the client-side, so it can run online or offline without necessity to install additional web engines. Moreover, it includes tools for measurement of free energies and free energy differences and data/image export.

  13. Surface transformation hardening on steels treated with solar energy in central tower and heliostats field

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, G.P.; Lopez, V.; de Damborenea, J.J.; Vazquez, A.J. [Centro Nacional de Investigaciones Metalurgicas CENIM/CSIC, Madrid (Spain)

    1995-04-28

    The possibility of surface hardening on AISI 4140 steel treated with concentrated solar energy in solar installations for electricity production has been studied. The samples were slides from a 35 mm diameter steel bar and their height was 35 mm. The quenching was made in water but also was considered the possibility of self-quenching by cooling in air. The amount of the surface hardness and the different structures obtained in both cases are presented, and some discussion is made with reference to the surface hardness, the hardness profiles and the structures obtained. The heating of steel with concentrated solar energy may produce similar hardening to that obtained with more conventional techniques of surface hardening

  14. Modeling the Surface Energy Balance of the Core of an Old Mediterranean City: Marseille.

    Science.gov (United States)

    Lemonsu, A.; Grimmond, C. S. B.; Masson, V.

    2004-02-01

    The Town Energy Balance (TEB) model, which parameterizes the local-scale energy and water exchanges between urban surfaces and the atmosphere by treating the urban area as a series of urban canyons, coupled to the Interactions between Soil, Biosphere, and Atmosphere (ISBA) scheme, was run in offline mode for Marseille, France. TEB's performance is evaluated with observations of surface temperatures and surface energy balance fluxes collected during the field experiments to constrain models of atmospheric pollution and transport of emissions (ESCOMPTE) urban boundary layer (UBL) campaign. Particular attention was directed to the influence of different surface databases, used for input parameters, on model predictions. Comparison of simulated canyon temperatures with observations resulted in improvements to TEB parameterizations by increasing the ventilation. Evaluation of the model with wall, road, and roof surface temperatures gave good results. The model succeeds in simulating a sensible heat flux larger than heat storage, as observed. A sensitivity comparison using generic dense city parameters, derived from the Coordination of Information on the Environment (CORINE) land cover database, and those from a surface database developed specifically for the Marseille city center shows the importance of correctly documenting the urban surface. Overall, the TEB scheme is shown to be fairly robust, consistent with results from previous studies.

  15. Electronic structure of graphene on Ni surfaces with different orientation

    International Nuclear Information System (INIS)

    Pudikov, D.A.; Zhizhin, E.V.; Rybkin, A.G.; Rybkina, A.A.; Zhukov, Y.M.; Vilkov, O. Yu.; Shikin, A.M.

    2016-01-01

    An experimental study of the graphene, synthesized by propylene cracking on Ni surfaces with different orientation: (100) and (111), using angle-resolved photoemission, has been performed. It has been shown that graphene on Ni(111) had a perfect lateral structure due to consistency of their lattices, whereas graphene/Ni(100) consisted of a lot of domains. For both systems electronic structure was quite similar and demonstrated a strong bonding of graphene to the underlying Ni surface. After Au intercalation the electronic structure of graphene in both systems was shifted to the Fermi level and became linear in the vicinity of the K point of the Brillouin zone. - Highlights: • Graphene on Ni(111) is well-ordered, whereas on Ni(100) – multi-domain. • Graphene on Ni(111) and Ni(100) is strongly bonded with substrate. • Intercalation of Au atoms restores the linearity in dispersion and makes graphene quasi-free on both Ni(100) and Ni(111).

  16. Comparison of the effectiveness of different antimicrobial surface technologies

    Directory of Open Access Journals (Sweden)

    Buhl Sebastian

    2017-09-01

    Full Text Available The risk of infection via microbiologically contaminated surfaces has already been demonstrated by other publications. In this work two different antibacterial surface technologies transition metalloacids (AMiSTec and TiO2/AgNO3 (Health Complete were compared regarding feasibility as well as their advantages and disadvantages. The examination of the antimicrobial activity was assessed according to the JIS Z 2801. We could demonstrate that all of our tested samples showed a strong antimicrobial activity (>log 3 germ reduction in the JIS experiments. Furthermore this strong antibacterial effect could be shown already after <30min incubation and at low light intensity (approx. 300 Lux for the TiO2/AgNO3 samples. Both technologies provide a high potential for an improved infection control for example in a high risk environment like operation rooms or intensive care units.

  17. Characterization of the damage produced on different materials surfaces

    International Nuclear Information System (INIS)

    Dellavale Clara, Hector Damian

    2004-01-01

    In the present work the characterization techniques of surfaces ULOI and RIMAPS have been applied on laboratory samples made from aluminium, stainless steel and material based on fiberglass.The resultant surfaces of, chemical etching with corrosive agents Keller and Tucker, mechanic damage from the wear and tear of abrasive paper and sandrubbing with alumina particles, are analyzed to different level of damage.The systematic application of the above mentioned techniques is carried out with the objective of finding information, which allows to characterize the superficial damage, both in its incipient state as in the extreme situation revealed by the presence of etch pits. Important results have been obtained, in the characterization of the incipient stage of the chemical etching, using the curves of the normalized area.In addition, it was possible to verify the capacity of the techniques in the early detection of the preferential directions generated by the etch pits

  18. Controlled synthesis and photocatalytic properties of rhombic dodecahedral Ag3PO4 with high surface energy

    International Nuclear Information System (INIS)

    Xie, Yao; Huang, Zhaohui; Zhang, Zhijie; Zhang, Xiaoguang; Wen, Ruilong; Liu, Yangai; Fang, Minghao; Wu, Xiaowen

    2016-01-01

    Graphical abstract: The high amount of rhombic dodecahedral Ag 3 PO 4 particles with a high exposure of the {110} facets and high surface energy (the surface energy of the {110} facets was 1.31 J/m 2 , greater than that of the {100} facet (1.12 J/m 2 ).) exhibited excellent photocatalytic activity. - Highlights: • High contents of rhombic dodecahedral Ag 3 PO 4 photocatalysts are prepared. • Excessive EG can destroy the morphology of Ag 3 PO 4 in synthesis process. • The rhombic dodecahedral Ag 3 PO 4 exhibits high surface energy. • High surface energy implies high photocatalytic activity. - Abstract: In this study, a series of Ag 3 PO 4 photocatalysts with different contents of rhombic dodecahedral particles were prepared in one pot by a facile, novel hydrothermal method using ethylene glycol (EG), which served as both a morphology modifier and reducing agent. The effects of EG content on the morphologies of Ag 3 PO 4 photocatalysts were discussed. The photocatalytic activity of the Ag 3 PO 4 photocatalysts was evaluated by the degradation of methylene blue trihydrate under visible-light irradiation. With the use of 0.8% EG in the reaction solvent, the sample exhibited excellent photocatalytic activity, attributed to the high amount of rhombic dodecahedral Ag 3 PO 4 particles with a high exposure of the {110} facets and high surface energy. The surface energy of the {110} facets was 1.31 J/m 2 , greater than that of the {100} facet (1.12 J/m 2 ). However, with 1% EG in the reaction solvent, although the Ag 3 PO 4 photocatalysts were composed of a majority of rhombic dodecahedral Ag 3 PO 4 particles, tiny Ag particles formed from Ag + under the action of EG attached on the surface of the sample decreased the absorption of visible light, resulting in low photocatalytic activity.

  19. Improvement of a land surface model for accurate prediction of surface energy and water balances

    International Nuclear Information System (INIS)

    Katata, Genki

    2009-02-01

    In order to predict energy and water balances between the biosphere and atmosphere accurately, sophisticated schemes to calculate evaporation and adsorption processes in the soil and cloud (fog) water deposition on vegetation were implemented in the one-dimensional atmosphere-soil-vegetation model including CO 2 exchange process (SOLVEG2). Performance tests in arid areas showed that the above schemes have a significant effect on surface energy and water balances. The framework of the above schemes incorporated in the SOLVEG2 and instruction for running the model are documented. With further modifications of the model to implement the carbon exchanges between the vegetation and soil, deposition processes of materials on the land surface, vegetation stress-growth-dynamics etc., the model is suited to evaluate an effect of environmental loads to ecosystems by atmospheric pollutants and radioactive substances under climate changes such as global warming and drought. (author)

  20. Electron emission and energy loss in grazing collisions of protons with insulator surfaces

    International Nuclear Information System (INIS)

    Gravielle, M. S.; Miraglia, J. E.; Aldazabal, I.; Arnau, A.; Ponce, V. H.; Aumayr, F.; Lederer, S.; Winter, H.

    2007-01-01

    Electron emission from LiF, KCl, and KI crystal surfaces during grazing collisions of swift protons is studied using a first-order distorted-wave formalism. Owing to the localized character of the electronic structure of these surfaces, we propose a model that allows us to describe the process as a sequence of atomic transitions from different target ions. Experimental results are presented for electron emission from LiF and KI and energy loss from KI surfaces. Calculations show reasonable agreement with these experimental data. The role played by the charge of the incident particle is also investigated

  1. Repairability of Compomers with Different Methods of Surface Conditioning

    Directory of Open Access Journals (Sweden)

    P.Samimi

    2005-06-01

    Full Text Available Statement of Problem: Considering the cost and amount of time and also the quantity of tooth loss in the process of cavity preparation, repair of the restoration instead of itsreplacement would be much more efficient.Purpose: The aim of this study was to determine the effect of different methods of surface conditioning on the shear bond strength of repaired compomers.Materials and Methods: Sixty blocks of compomer were prepared in acrylic molds and then they were randomly divided into five groups of 12. Group I (control groupreceived no treatment. The remaining samples were immersed in 37 ºC distilled water for one week, then the surfaces were roughened with a coarse diamond bur. Samples ineach group were prepared by different surface treatment and conditioning: In group II specimens were conditioned with 35% phosphoric acid for 20s. Specimens in group III were etched with 10% polyacrylic acid for 20s. In group IV 1.23% acidulated phosphatefluoride was applied for 30s, and compomer surfaces were sandblasted with 50μm Al2O3 powder in group V. After the initial preparations, all groups were treated with silane and resin before bonding of the second mix of compomer. Shear forces were applied with a universal testing machine at a cross-head speed of 5mm/min. The data were analyzed using one-way ANOVA and Duncan's multiple range tests.Results: The mean shear bond strengths and standard deviations (in parentheses for groups I to V were 31.56(10.86, 20.02(5.49, 17.74(7.34, 19.31(4.31 and 27.7(6.33MPa, respectively. The mean bond strengths for Groups I and V were significantly higher than that of the other groups (P<0.05.Conclusion: The results showed that among the surface treatments used in this study,sandblasting with alumina could be the best surface preparation method for repairing compomer restorations.

  2. Treatment of surfaces with low-energy electrons

    Energy Technology Data Exchange (ETDEWEB)

    Frank, L., E-mail: ludek@isibrno.cz [Institute of Scientific Instruments of the CAS, v.v.i., Královopolská 147, 61264 Brno (Czech Republic); Mikmeková, E. [Institute of Scientific Instruments of the CAS, v.v.i., Královopolská 147, 61264 Brno (Czech Republic); FEI Company, Achtseweg Noord 5, 5651 GG Eindhoven (Netherlands); Lejeune, M. [LPMC – Faculte des Sciences d’Amiens, Universite de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex 2 (France)

    2017-06-15

    Highlights: • Using proper irradiation parameters, adsorbed hydrocarbons are released from surfaces. • Slow electrons remove hydrocarbons instead of depositing carbon. • Prolonged irradiation with very slow electrons does not create defects in graphene. - Abstract: Electron-beam-induced deposition of various materials from suitable precursors has represented an established branch of nanotechnology for more than a decade. A specific alternative is carbon deposition on the basis of hydrocarbons as precursors that has been applied to grow various nanostructures including masks for subsequent technological steps. Our area of study was unintentional electron-beam-induced carbon deposition from spontaneously adsorbed hydrocarbon molecules. This process traditionally constitutes a challenge for scanning electron microscopy practice preventing one from performing any true surface studies outside an ultrahigh vacuum and without in-situ cleaning of samples, and also jeopardising other electron-optical devices such as electron beam lithographs. Here we show that when reducing the energy of irradiating electrons sufficiently, the e-beam-induced deposition can be converted to e-beam-induced release causing desorption of hydrocarbons and ultimate cleaning of surfaces in both an ultrahigh and a standard high vacuum. Using series of experiments with graphene samples, we demonstrate fundamental features of e-beam-induced desorption and present results of checks for possible radiation damage using Raman spectroscopy that led to optimisation of the electron energy for damage-free cleaning. The method of preventing carbon contamination described here paves the way for greatly enhanced surface sensitivity of imaging and substantially reduced demands on vacuum systems for nanotechnological applications.

  3. Treatment of surfaces with low-energy electrons

    Czech Academy of Sciences Publication Activity Database

    Frank, Luděk; Mikmeková, Eliška; Lejeune, M.

    2017-01-01

    Roč. 407, JUN 15 (2017), s. 105-108 ISSN 0169-4332 R&D Projects: GA TA ČR(CZ) TE01020118; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : Low- energy electrons * Electron beam induced release * Graphene * Ultimate cleaning of surfaces Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Nano-processes (applications on nano-scale) Impact factor: 3.387, year: 2016

  4. Low-energy electron scattering from molecules, biomolecules and surfaces

    CERN Document Server

    Carsky, Petr

    2011-01-01

    Since the turn of the 21st century, the field of electron molecule collisions has undergone a renaissance. The importance of such collisions in applications from radiation chemistry to astrochemistry has flowered, and their role in industrial processes such as plasma technology and lighting are vital to the advancement of next generation devices. Furthermore, the development of the scanning tunneling microscope highlights the role of such collisions in the condensed phase, in surface processing, and in the development of nanotechnology.Low-Energy Electron Scattering from Molecules, Biomolecule

  5. Methodological differences behind energy statistics for steel production – Implications when monitoring energy efficiency

    International Nuclear Information System (INIS)

    Morfeldt, Johannes; Silveira, Semida

    2014-01-01

    Energy efficiency indicators used for evaluating industrial activities at the national level are often based on statistics reported in international databases. In the case of the Swedish iron and steel sector, energy consumption statistics published by Odyssee, Eurostat, the IEA (International Energy Agency), and the United Nations differ, resulting in diverging energy efficiency indicators. For certain years, the specific energy consumption for steel is twice as high if based on Odyssee statistics instead of statistics from the IEA. The analysis revealed that the assumptions behind the allocation of coal and coke used in blast furnaces as energy consumption or energy transformation are the major cause for these differences. Furthermore, the differences are also related to errors in the statistical data resulting from two different surveys that support the data. The allocation of coal and coke has implications when promoting resource as well as energy efficiency at the systems level. Eurostat's definition of energy consumption is more robust compared to the definitions proposed by other organisations. Nevertheless, additional data and improved energy efficiency indicators are needed to fully monitor the iron and steel sector's energy system and promote improvements towards a greener economy at large. - Highlights: • Energy statistics for the iron and steel sector diverge in international databases. • Varying methods have implications when monitoring energy and resource efficiency. • Allocation of blast furnaces as transformation activities is behind the differences. • Different statistical surveys and human error also contribute to diverging results

  6. Stabilized quasi-Newton optimization of noisy potential energy surfaces

    International Nuclear Information System (INIS)

    Schaefer, Bastian; Goedecker, Stefan; Alireza Ghasemi, S.; Roy, Shantanu

    2015-01-01

    Optimizations of atomic positions belong to the most commonly performed tasks in electronic structure calculations. Many simulations like global minimum searches or characterizations of chemical reactions require performing hundreds or thousands of minimizations or saddle computations. To automatize these tasks, optimization algorithms must not only be efficient but also very reliable. Unfortunately, computational noise in forces and energies is inherent to electronic structure codes. This computational noise poses a severe problem to the stability of efficient optimization methods like the limited-memory Broyden–Fletcher–Goldfarb–Shanno algorithm. We here present a technique that allows obtaining significant curvature information of noisy potential energy surfaces. We use this technique to construct both, a stabilized quasi-Newton minimization method and a stabilized quasi-Newton saddle finding approach. We demonstrate with the help of benchmarks that both the minimizer and the saddle finding approach are superior to comparable existing methods

  7. Experimental survey of the potential energy surfaces associated with fission

    International Nuclear Information System (INIS)

    Britt, H.C.

    1980-01-01

    Progress in the experimental determination of the properties of the potential energy surface associated with fission is reviewed. The importance of nuclear symmetry effects on the calculation of fission widths is demonstrated. Evidence is presented for the fragmentation of the mass-asymmetric second barrier in the thorium region and the axial asymmetric first barrier in the californium region. Detailed analyses of experimental data suggest the presence of two parallel second barriers; the normal mass-asymmetric, axial-symmetric barrier and a slightly higher mass-symmetric, axial-asymmetric barrier. Experimental barrier parameters are determined systematically and compared with calculations from various theoretical models. Techniques for expanding fission probability measurements to higher energies are discussed. (author)

  8. Stabilized quasi-Newton optimization of noisy potential energy surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, Bastian; Goedecker, Stefan, E-mail: stefan.goedecker@unibas.ch [Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel (Switzerland); Alireza Ghasemi, S. [Institute for Advanced Studies in Basic Sciences, P.O. Box 45195-1159, IR-Zanjan (Iran, Islamic Republic of); Roy, Shantanu [Computational and Systems Biology, Biozentrum, University of Basel, CH-4056 Basel (Switzerland)

    2015-01-21

    Optimizations of atomic positions belong to the most commonly performed tasks in electronic structure calculations. Many simulations like global minimum searches or characterizations of chemical reactions require performing hundreds or thousands of minimizations or saddle computations. To automatize these tasks, optimization algorithms must not only be efficient but also very reliable. Unfortunately, computational noise in forces and energies is inherent to electronic structure codes. This computational noise poses a severe problem to the stability of efficient optimization methods like the limited-memory Broyden–Fletcher–Goldfarb–Shanno algorithm. We here present a technique that allows obtaining significant curvature information of noisy potential energy surfaces. We use this technique to construct both, a stabilized quasi-Newton minimization method and a stabilized quasi-Newton saddle finding approach. We demonstrate with the help of benchmarks that both the minimizer and the saddle finding approach are superior to comparable existing methods.

  9. Polynomials, Riemann surfaces, and reconstructing missing-energy events

    CERN Document Server

    Gripaios, Ben; Webber, Bryan

    2011-01-01

    We consider the problem of reconstructing energies, momenta, and masses in collider events with missing energy, along with the complications introduced by combinatorial ambiguities and measurement errors. Typically, one reconstructs more than one value and we show how the wrong values may be correlated with the right ones. The problem has a natural formulation in terms of the theory of Riemann surfaces. We discuss examples including top quark decays in the Standard Model (relevant for top quark mass measurements and tests of spin correlation), cascade decays in models of new physics containing dark matter candidates, decays of third-generation leptoquarks in composite models of electroweak symmetry breaking, and Higgs boson decay into two tau leptons.

  10. Intermolecular potential energy surface and thermophysical properties of propane.

    Science.gov (United States)

    Hellmann, Robert

    2017-03-21

    A six-dimensional potential energy surface (PES) for the interaction of two rigid propane molecules was determined from supermolecular ab initio calculations up to the coupled cluster with single, double, and perturbative triple excitations level of theory for 9452 configurations. An analytical site-site potential function with 14 sites per molecule was fitted to the calculated interaction energies. To validate the analytical PES, the second virial coefficient and the dilute gas shear viscosity and thermal conductivity of propane were computed. The dispersion part of the potential function was slightly adjusted such that quantitative agreement with the most accurate experimental data for the second virial coefficient at room temperature was achieved. The adjusted PES yields values for the three properties that are in very good agreement with the best experimental data at all temperatures.

  11. A topological screening heuristic for low-energy, high-index surfaces

    Science.gov (United States)

    Sun, Wenhao; Ceder, Gerbrand

    2018-03-01

    Robust ab initio investigations of nanoparticle surface properties require a method to identify candidate low-energy surface facets a priori. By assuming that low-energy surfaces are planes with high atomic density, we devise an efficient algorithm to screen for low-energy surface orientations, even if they have high (hkl) miller indices. We successfully predict the observed low-energy, high-index { 10 12 bar } and { 10 1 bar 4 } surfaces of hematite α-Fe2O3, the {311} surfaces of cuprite Cu2O, and the {112} surfaces of anatase TiO2. We further tabulate candidate low-energy surface orientations for nine of the most common binary oxide structures. Screened surfaces are found to be generally applicable across isostructural compounds with varying chemistries, although relative surface energies between facets may vary based on the preferred coordination of the surface atoms.

  12. Resonance Energy Transfer in Hybrid Devices in the Presence of a Surface

    DEFF Research Database (Denmark)

    Kopylov, Oleksii; Huck, Alexander; Kadkhodazadeh, Shima

    2014-01-01

    to approximately 10 nm was observed. By comparing the carrier dynamics of the quantum wells and the nanocrystals, we found that nonradiative recombination via surface states, generated during dry etching of the wafer, counteracts the nonradiative energy-transfer process to the nanocrystals and therefore decreases......We have studied room-temperature, nonradiative resonant energy transfer from InGaN/GaN quantum wells to CdSe/ZnS nanocrystals separated by aluminum oxide layers of different thicknesses. Nonradiative energy transfer from the quantum wells to the nanocrystals at separation distances of up...

  13. Bacterial biofilm formation in different surfaces of food industries

    Directory of Open Access Journals (Sweden)

    Karine Angélica Dalla Costa

    2017-06-01

    Full Text Available The term biofilm describes the sessile microbial life form, characterized by microorganism adhesion to any surface and with the production of extracellular polymeric substances. In food industries, the formation of biofilms results in serious problems, since it can be a contamination source of the food product, compromising the final product quality and consumer health. The aim of this study was to verify the adhesion of biofilms (sessile cells of pathogenic and/or deteriorating bacteria against surfaces of the food industry. The bacterial species tested were Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, Listeria monocytogenes ATCC 19117 and Salmonella Typhimurium ATCC 14028. It was used stainless steel and polypropylene coupons as contact surfaces. The results demonstrated that P. aeruginosa and S. Typhimurium showed higher biofilm formation capacity. Statistically, there was no difference in count of P. aeruginosa and S. Typhimurium (p > 0.05 cells. The same occurred between L. monocytogenes and S. aureus. However, the counts of P. aeruginosa and S. Typhimurium cells were statistically higher than S. aureus and L. monocytogenes (p < 0.05. By means of scanning electron microscopy it was also found increased adhesion of P. aeruginosa. The results revealed that P. aeruginosa was the bacterial species with higher biofilm formation capacity among the others.

  14. Regional energy consumption and income differences in Denmark

    DEFF Research Database (Denmark)

    Klinge Jacobsen, Henrik

    2003-01-01

    income of households grouped in income deciles and by other characteristics. The impact of environmental taxes depends on income levels in rural areas compared to income in urban areas. In Denmark, the income difference is found to be quite small, but energy consumption and, therefore, also the burden......Internationally a debate on the distributional impact of energy taxation has focused on the tax burden relative to income. The general conclusion is that taxes are regressive, but at a varying degree for different countries. This study examines the relationship between location, income, heating...... technology characteristics and the energy tax that households pay. The article aims at identifying general implications of energy taxes with respect to different impacts on population groups depending on location and income. Tax payments associated with energy use are considered relative to total disposable...

  15. Energy consumption in buildings for different sport activities

    Energy Technology Data Exchange (ETDEWEB)

    Norrfors, M; Werner, G; Oertenstrand, G

    1978-01-01

    Some buildings for different kinds of sport activities have a great energy demand. The actions which could be taken in order to decrease the energy demand and at the same time decrease the operating costs for these buildings are summarized. References are given to literature of current interest in this field.

  16. Forces on nuclei moving on autoionizing molecular potential energy surfaces.

    Science.gov (United States)

    Moiseyev, Nimrod

    2017-01-14

    Autoionization of molecular systems occurs in diatomic molecules and in small biochemical systems. Quantum chemistry packages enable calculation of complex potential energy surfaces (CPESs). The imaginary part of the CPES is associated with the autoionization decay rate, which is a function of the molecular structure. Molecular dynamics simulations, within the framework of the Born-Oppenheimer approximation, require the definition of a force field. The ability to calculate the forces on the nuclei in bio-systems when autoionization takes place seems to rely on an understanding of radiative damages in RNA and DNA arising from the release of slow moving electrons which have long de Broglie wavelengths. This work addresses calculation of the real forces on the nuclei moving on the CPES. By using the transformation of the time-dependent Schrödinger equation, previously used by Madelung, we proved that the classical forces on nuclei moving on the CPES correlated with the gradient of the real part of the CPES. It was proved that the force on the nuclei of the metastable molecules is time independent although the probability to detect metastable molecules exponentially decays. The classical force is obtained from the transformed Schrödinger equation when ℏ=0 and the Schrödinger equation is reduced to the classical (Newtonian) equations of motion. The forces on the nuclei regardless on what potential energy surface they move (parent CPES or product real PESs) vary in time due to the autoionization process.

  17. Surface modification of TA2 pure titanium by low energy high current pulsed electron beam treatments

    International Nuclear Information System (INIS)

    Gao Yukui

    2011-01-01

    Surface integrity changes of TA2 pure titanium including surface topography, microstructure and nanohardness distribution along surface layer were investigated by different techniques of low energy high current pulsed electron beam treatments (LEHCPEBTs). The surface topography was characterized by SEM. Moreover, the TEM observation and X-ray diffraction analysis were performed to reveal the surface modification mechanism of TA2 pure titanium by LEHCPEBTs. The surface roughness was modified by electron beam treatment and the polishing mechanism was analyzed by studying the cross section microstructure of electron beam treated specimens by SEM and TEM. The results show that the surface finish obtains good polishing quality and there is no phase transformation but the dislocations by LEHCPEBT. Furthermore, the nanohardness in the surface modified layer is improved. The remelt and fine-grain microstructure of surface layer caused by LEHCPEBTs are the main polishing mechanism and the reason of modification of surface topography and the increment in nanohardness is mainly due to the dislocations and fine grains in the modified layer induced by LEHCPEBT.

  18. Free energy surfaces from nonequilibrium processes without work measurement

    Science.gov (United States)

    Adib, Artur B.

    2006-04-01

    Recent developments in statistical mechanics have allowed the estimation of equilibrium free energies from the statistics of work measurements during processes that drive the system out of equilibrium. Here a different class of processes is considered, wherein the system is prepared and released from a nonequilibrium state, and no external work is involved during its observation. For such "clamp-and-release" processes, a simple strategy for the estimation of equilibrium free energies is offered. The method is illustrated with numerical simulations and analyzed in the context of tethered single-molecule experiments.

  19. An Energy Conservation Approach to Adsorbate-Induced Surface Stress and the Extraction of Binding Energy Using Nanomechanics

    Energy Technology Data Exchange (ETDEWEB)

    Pinnaduwage, Lal A [ORNL; Boiadjiev, Vassil I [ORNL; Fernando, G. W. [University of Connecticut, Storrs; Hawk, J. E. [Oak Ridge National Laboratory (ORNL); Wijewardhana, L.C. R. [University of Cincinnati; Gehl, Anthony C [ORNL

    2008-01-01

    Microcantilevers are ideally-suited for the study of surface phenomena due to their large surface-to-volume ratios, which amplify surface effects. We show that when guest molecules bind to atoms/molecules on a microcantilever surface, the released binding energy is retained in the host surface, leading to a metastable state where the excess energy on the surface is manifested as an increase in surface stress leading to the bending of the microcantilever. When the excess energy is released, the microcantilever relaxes back to the original state, and the relaxation time depends on the particular binding process involved. Such experiments were conducted for three binding processes in vapor phase experiments: physisorption, hydrogen bonding, and chemisorption. To our knowledge, such an energy conservation approach has not been taken into account in adsorbate-induced surface effect investigations. Furthermore, these experiments illustrate that detailed molecular-level information on binding energies can be extracted from this simple micromechanical sensor.

  20. Energy dissipation of highly charged ions interacting with solid surfaces; Energieeintrag langsamer hochgeladener Ionen in Festkoerperoberflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Kost, D.

    2006-07-01

    Motivated by the incomplete scientific description of the relaxation of highly charged ions in front of solid surfaces and their energy balance, this thesis describes an advanced complementary study of determining deposited fractions and re-emitted fractions of the potential energy of highly charged ions. On one side, a calorimetric measurement setup is used to determine the retained potential energy and on the other side, energy resolved electron spectroscopy is used for measuring the reemitted energy due to secondary electron emission. In order to study the mechanism of energy retention in detail, materials with different electronic structures are investigated: Cu, n-Si, p-Si and SiO{sub 2}. In the case of calorimetry, a linear relationship between the deposited potential energy and the inner potential energy of the ions was determined. The total potential energy which stays in the solid remains almost constant at about (80 {+-} 10) %. Comparing the results of the Cu, n-Si and p-Si targets, no significant difference could be shown. Therefore we conclude that the difference in energy deposition between copper, n-doped Si and p-doped Si is below 10 %, which is significantly lower than using SiO{sub 2} targets. For this purpose, electron spectroscopy provides a complementary result. For Cu and Si surfaces, an almost linear increase of the re-emitted energy with increasing potential energy of the ion up to Ar{sup 7+} was also observed. The ratio of the re-emitted energy is about (10 {+-} 5) % of the total potential energy of the incoming ion, almost independent of the ion charge state. In contrast, an almost vanishing electron emission was observed for SiO{sub 2} and for charge states below q=7. For Ar{sup 8+} and Ar{sup 9+}, the electron emission increased due to the contribution of the projectile LMM Auger electrons and the re-emitted energy amounts up to 20 % for Cu and Si and around 10 % for SiO{sub 2}. These results are in good agreement with the calorimetric

  1. Experimental and numerical investigations of the impingement of an oblique liquid jet onto a superhydrophobic surface: energy transformation

    Energy Technology Data Exchange (ETDEWEB)

    Kibar, Ali, E-mail: alikibar@kocaeli.edu.tr [Department of Mechanical and Material Technologies, Kocaeli University, 41285, Arslanbey Campus, Kocaeli (Turkey)

    2016-02-15

    This study presents the theory of impinging an oblique liquid jet onto a vertical superhydrophobic surface based on both experimental and numerical results. A Brassica oleracea leaf with a 160° apparent contact angle was used for the superhydrophobic surface. Distilled water was sent onto the vertical superhydrophobic surface in the range of 1750–3050 Reynolds number, with an inclination angle of 20°−40°, using a circular glass tube with a 1.75 mm inner diameter. The impinging liquid jet spread onto the surface governed by the inertia of the liquid and then reflected off the superhydrophobic surface due to the surface energy of the spreading liquid. Two different energy approaches, which have time-scale and per-unit length, were performed to determine transformation of the energy. The kinetic energy of the impinging liquid jet was transformed into the surface energy with an increasing interfacial surface area between the liquid and air during spreading. Afterwards, this surface energy of the spreading liquid was transformed into the reflection kinetic energy. (paper)

  2. Surface-enhanced Raman scattering of dipolar molecules by the graphene Fermi surface modulation with different dipole moments

    Science.gov (United States)

    Zhang, Mingjia; Leng, Yandan; Huang, Jing; Yu, JiaoJiao; Lan, Zhenggang; Huang, Changshui

    2017-12-01

    We report the modulation of Raman scattering spectrum of chromophore/graphene hybrids by tunning the molecular polarization with different terminal groups (methyl, methoxy, nitrile, and two nitros). Based on the density functional theory, the specific dipole moment values of the chromophore molecules are calculated. An obvious surface-enhanced Raman scattering (SERS) was observed and the scattering intensity of molecule increases with enlarged dipole moment. According to the analysis of G band Raman shifts of graphene, the enhancement of the Raman signal can be attributed to strong electronic coupling between graphene and chromophore, which is closely related with the modulation of graphene Fermi surface by changing the dipole moment of the molecule. Besides, the optimization of the ground state geometry and the binding energy of the hybrids were also calculated with the Density Functional Based Tight Bonding (DFTB) method, which confirms that the enhanced Raman scattering of molecules on graphene arises from the improved energy level matching between graphene Fermi surface and molecular band, further providing a new way to design novel SERS devices.

  3. Low energy ion scattering (LEIS) and the compositional and structural analysis of solid surfaces

    International Nuclear Information System (INIS)

    Berg, J.A. van den; Armour, D.G.

    1981-01-01

    The physics of Low Energy Ion Scattering (LEIS) and its application as a surface analytical technique are reviewed. It is shown that compositional and short-range structural information can be obtained by choosing experimental conditions which optimize the contributions of single and double (or multiple) collisions, respectively. The LEIS technique allows mass analysis in a straightforward way, possesses a high surface selectivity but is unable to provide quantitative information in isolation due to scattering cross-section uncertainties and not easily quantifiable charge exchange effects. Structural information regarding adsorbate positions on single crystal surfaces and the short-range substrate structure (including damaged and reconstructed surfaces) can be obtained by exploiting shadowing and/or multiple scattering phenomena. The progress made in recent years in this area is charted. It is shown that computer simulations often play an important role in this type of study. Effects, such as charge exchange, inelastic energy loss and ion beam surface perturbations, which complicate the use of low energy ion scattering for surface analysis are discussed in detail. The present status of the technique in the different areas of study is indicated. (author)

  4. Tuning the giant Rashba effect on a BiAg2 surface alloy: Two different approaches

    International Nuclear Information System (INIS)

    Frantzeskakis, E.; Crepaldi, A.; Pons, S.; Kern, K.; Grioni, M.

    2010-01-01

    We discuss two different approaches for tuning the giant spin-orbit splitting of a BiAg 2 surface alloy. The first approach consists of electron doping by alkaline metal deposition in order to shift the energy position of the spin-split surface states, while the second is based on the novel Si(1 1 1)-Ag-BiAg 2 trilayer system. In both cases the spin-polarized structure near the Fermi level can be controlled by an external parameter, while the second approach permits coupling the concept of giant spin-splitting with a semiconducting substrate.

  5. Computed Potential Energy Surfaces and Minimum Energy Pathways for Chemical Reactions

    Science.gov (United States)

    Walch, Stephen P.; Langhoff, S. R. (Technical Monitor)

    1994-01-01

    Computed potential energy surfaces are often required for computation of such parameters as rate constants as a function of temperature, product branching ratios, and other detailed properties. For some dynamics methods, global potential energy surfaces are required. In this case, it is necessary to obtain the energy at a complete sampling of all the possible arrangements of the nuclei, which are energetically accessible, and then a fitting function must be obtained to interpolate between the computed points. In other cases, characterization of the stationary points and the reaction pathway connecting them is sufficient. These properties may be readily obtained using analytical derivative methods. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method to obtain accurate energetics, gives usefull results for a number of chemically important systems. The talk will focus on a number of applications including global potential energy surfaces, H + O2, H + N2, O(3p) + H2, and reaction pathways for complex reactions, including reactions leading to NO and soot formation in hydrocarbon combustion.

  6. Surface energy loss processes in XPS studied by absolute reflection electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    Nagatomi, T.; Goto, K.

    2010-01-01

    The results of the investigation of the inelastic interaction of 300-3000 eV electrons with the Ni and Au surfaces by the analysis of absolute reflection electron energy loss spectroscopy (REELS) spectra were described. The present analysis enables the inelastic mean free path (IMFP), surface excitation parameter (SEP) and differential SEP (DSEP) to be obtained simultaneously from an absolute REELS spectrum. The obtained IMFPs for Ni and Au showed a good agreement with those calculated using the TPP-2M predictive equation. The present SEPs determined for Ni and Au were fitted to the Chen's formula describing the dependence of the SEP on the electron energy, and material parameters for Ni and Au in Chen's formula were proposed. The present DESPs were compared with the theoretical results, and a reasonable agreement between the experimentally determined DSEPs and theoretical results was confirmed. The MC modeling of calculating the REELS spectrum, in which energy loss processes due to surface excitations are taken into account, was also described. The IMFP, SEP and DSEP determined by the present absolute REELS analysis were employed to describe energy loss processes by inelastic scattering in the proposed MC simulation. The simulated REELS spectra were found to be in a good agreement with the experimental spectra for both Ni and Au.

  7. Effect of different glucose supply conditions on neuronal energy metabolism

    OpenAIRE

    Zheng, Hongwen; Wang, Rubin; Qu, Jingyi

    2016-01-01

    The glucose-excited neurons in brain can sense blood glucose levels and reflect different firing states, which are mainly associated with regulation of blood glucose and energy demand in the brain. In this paper, a new model of glucose-excited neuron in hypothalamus is proposed. The firing properties and energy consumption of this type of neuron under conditions of different glucose levels are simulated and analyzed. The results show that the firing rate and firing duration of the neuron both...

  8. Proper surface channelling of low energy argon ions incident on a nickel (110) crystal

    International Nuclear Information System (INIS)

    Evdokimov, I.N.; Berg, J.A. van den; Armour, D.G.

    1979-01-01

    The scattering behaviour of 6 keV argon ions from a nickel (110) surface has been investigated for specular reflection under grazing incidence conditions. The occurrence of an anomalously high energy loss has been confirmed and the transition from chain scattering at large scattering angles to a distinctly different type of scattering at small angles has been investigated. The characteristics of the low angle scattering phenomena, which dominate the observed spectra at scattering angles below about 18 0 , may be explained in terms of a surface hyperchannelling model in which the incident ions are confined to move within the shallow 'potential valleys' between two atomic rows in the surface. The critical angle for occurrence of this phenomena which is distinctly different from surface semichannelling has been evaluated with Lindhard's standard string potential. The experimentally measured critical angles are in good agreement with the calculated ones. (author)

  9. Cultural energy analyses of dairy cattle receiving different concentrate levels

    International Nuclear Information System (INIS)

    Koknaroglu, Hayati

    2010-01-01

    Purpose of this study was to conduct cultural energy analyses of dairy cows receiving different levels of concentrate. Data were acquired by conducting a survey on 132 dairy farms selected by the stratified random sampling method. Dairy cattle farms were divided into three groups according to concentrate level and were analyzed. Accordingly concentrate levels were assigned as low (LLC) ( 50%, 44 farms). Cultural energy used for feed for cows was calculated by multiplying each ingredient with corresponding values of ingredients from literature. Transportation energy was also included in the analysis. Total cultural energy expended was highest for LLC (P < 0.05). Cultural energy expended for feed constituted more than half of the total cultural energy and was highest for LLC (P < 0.05). Cultural energy expended per kg milk and per Mcal protein energy was higher for LLC (P < 0.05). Efficiency defined as Mcal input/Mcal output was better for ILC and was worse for LLC (P < 0.05) and HLC was intermediate thus not differing from other groups. Results show that cultural energy use efficiency does not linearly increases as concentrate level increases and increasing concentrate level does not necessarily mean better efficiency. Thus optimum concentrate level not interfering cows performance should be sought for sustainable dairy production.

  10. Nanoscale control of energy and matter in plasma-surface interactions: towards energy-efficient nanotech

    Science.gov (United States)

    Ostrikov, Kostya

    2010-11-01

    This presentation focuses on the plasma issues related to the solution of the grand challenge of directing energy and matter at nanoscales. This ability is critical for the renewable energy and energy-efficient technologies for sustainable future development. It will be discussed how to use environmentally and human health benign non-equilibrium plasma-solid systems and control the elementary processes of plasma-surface interactions to direct the fluxes of energy and matter at multiple temporal and spatial scales. In turn, this makes it possible to achieve the deterministic synthesis of self- organised arrays of metastable nanostructures in the size range beyond the reach of the present-day nanofabrication. Such structures have tantalising prospects to enhance performance of nanomaterials in virtually any area of human activity yet remain almost inaccessible because the Nature's energy minimisation rules allow only a small number of stable equilibrium states. By using precisely controlled and kinetically fast nanoscale transfer of energy and matter under non-equilibrium conditions and harnessing numerous plasma- specific controls of species creation, delivery to the surface, nucleation and large-scale self-organisation of nuclei and nanostructures, the arrays of metastable nanostructures can be created, arranged, stabilised, and further processed to meet the specific requirements of the envisaged applications. These approaches will eventually lead to faster, unprecedentedly- clean, human-health-friendly, and energy-efficient nanoscale synthesis and processing technologies for the next-generation renewable energy and light sources, biomedical devices, information and communication systems, as well as advanced functional materials for applications ranging from basic food, water, health and clean environment needs to national security and space missions.

  11. Net energy analysis of different electricity generation systems

    International Nuclear Information System (INIS)

    1994-07-01

    This document is a report on the net energy analysis of nuclear power and other electricity generation systems. The main objectives of this document are: To provide a comprehensive review of the state of knowledge on net energy analysis of nuclear and other energy systems for electricity generation; to address traditional questions such as whether nuclear power is a net energy producer or not. In addition, the work in progress on a renewed application of the net energy analysis method to environmental issues is also discussed. It is expected that this work could contribute to the overall comparative assessment of different energy systems which is an ongoing activity at the IAEA. 167 refs, 9 figs, 5 tabs

  12. Surface layer scintillometry for estimating the sensible heat flux component of the surface energy balance

    Directory of Open Access Journals (Sweden)

    M. J. Savage

    2010-01-01

    Full Text Available The relatively recently developed scintillometry method, with a focus on the dual-beam surface layer scintillometer (SLS, allows boundary layer atmospheric turbulence, surface sensible heat and momentum flux to be estimated in real-time. Much of the previous research using the scintillometer method has involved the large aperture scintillometer method, with only a few studies using the SLS method. The SLS method has been mainly used by agrometeorologists, hydrologists and micrometeorologists for atmospheric stability and surface energy balance studies to obtain estimates of sensible heat from which evaporation estimates representing areas of one hectare or larger are possible. Other applications include the use of the SLS method in obtaining crucial input parameters for atmospheric dispersion and turbulence models. The SLS method relies upon optical scintillation of a horizontal laser beam between transmitter and receiver for a separation distance typically between 50 and 250 m caused by refractive index inhomogeneities in the atmosphere that arise from turbulence fluctuations in air temperature and to a much lesser extent the fluctuations in water vapour pressure. Measurements of SLS beam transmission allow turbulence of the atmosphere to be determined, from which sub-hourly, real-time and in situ path-weighted fluxes of sensible heat and momentum may be calculated by application of the Monin-Obukhov similarity theory. Unlike the eddy covariance (EC method for which corrections for flow distortion and coordinate rotation are applied, no corrections to the SLS measurements, apart from a correction for water vapour pressure, are applied. Also, path-weighted SLS estimates over the propagation path are obtained. The SLS method also offers high temporal measurement resolution and usually greater spatial coverage compared to EC, Bowen ratio energy balance, surface renewal and other sensible heat measurement methods. Applying the shortened surface

  13. Making waves: Kinetic processes controlling surface evolution during low energy ion sputtering

    International Nuclear Information System (INIS)

    Chan, W.L.; Chason, Eric

    2007-01-01

    When collimated beams of low energy ions are used to bombard materials, the surface often develops a periodic pattern or ''ripple'' structure. Different types of patterns are observed to develop under different conditions, with characteristic features that depend on the substrate material, the ion beam parameters, and the processing conditions. Because the patterns develop spontaneously, without applying any external mask or template, their formation is the expression of a dynamic balance among fundamental surface kinetic processes, e.g., erosion of material from the surface, ion-induced defect creation, and defect-mediated evolution of the surface morphology. In recent years, a comprehensive picture of the different kinetic mechanisms that control the different types of patterns that form has begun to emerge. In this article, we provide a review of different mechanisms that have been proposed and how they fit together in terms of the kinetic regimes in which they dominate. These are grouped into regions of behavior dominated by the directionality of the ion beam, the crystallinity of the surface, the barriers to surface roughening, and nonlinear effects. In sections devoted to each type of behavior, we relate experimental observations of patterning in these regimes to predictions of continuum models and to computer simulations. A comparison between theory and experiment is used to highlight strengths and weaknesses in our understanding. We also discuss the patterning behavior that falls outside the scope of the current understanding and opportunities for advancement

  14. U. K. surface passenger transport sector. Energy consumption and policy options for conservation

    Energy Technology Data Exchange (ETDEWEB)

    Maltby, D; Monteath, I G; Lawler, K A

    1978-12-01

    Forecasts of U.K. energy consumption in this sector for four future scenarios based on different economic growth rates, energy prices, and energy conservation policies, show that by the year 2000, private transport will probably account for 76-94% of total energy consumption in surface passenger transport. A 33% increase in the average miles-per-gallon fuel consumption through technological improvements in private vehicles, conversion of private vehicles to diesel oil, additional fuel taxation equivalent to 25 or 50% fuel price increase, a 10% reduction in average car engine size (encouraged by taxation), and changes in public transport technology offer energy savings of about 20, 5-10, 6.3 or 12.5, 2-4, and 2%, respectively. There is considerable uncertainty about the outcome of these options.

  15. Methods for comparative risk assessment of different energy sources

    International Nuclear Information System (INIS)

    1992-10-01

    The environmental and health aspects of different energy systems, particularly those associated with the generation of electricity, are emerging as significant issues for policy formulation and implementation. This, together with the growing need of many countries to define their energy programmes for the next century, has provided the basis for a renewed interest in the comparative risk assessment of different energy sources (fossil, nuclear, renewables). This document is the outcome of a Specialists Meeting on the procedural and methodological issues associated with comparative health and environmental risks of different energy sources. After an introductory chapter outlining the issues under consideration the papers presented at the Meeting, which have been indexed separately, are given. Refs, figs and tabs

  16. Surface Modification of MXenes: A Pathway to Improve MXene Electrode Performance in Electrochemical Energy Storage Devices

    KAUST Repository

    Ahmed, Bilal

    2017-12-31

    The recent discovery of layered transition metal carbides (MXenes) is one of the most important developments in two-dimensional (2D) materials. Preliminary theoretical and experimental studies suggest a wide range of potential applications for MXenes. The MXenes are prepared by chemically etching ‘A’-layer element from layered ternary metal carbides, nitrides and carbonitrides (MAX phases) through aqueous acid treatment, which results in various surface terminations such as hydroxyl, oxygen or fluorine. It has been found that surface terminations play a critical role in defining MXene properties and affects MXene performance in different applications such as electrochemical energy storage, electromagnetic interference shielding, water purification, sensors and catalysis. Also, the electronic, thermoelectric, structural, plasmonic and optical properties of MXenes largely depend upon surface terminations. Thus, controlling the surface chemistry if MXenes can be an efficient way to improve their properties. This research mainly aims to perform surface modifications of two commonly studied MXenes; Ti2C and Ti3C2, via chemical, thermal or physical processes to enhance electrochemical energy storage properties. The as-prepared and surface modified MXenes have been studied as electrode materials in Li-ion batteries (LIBs) and supercapacitors (SCs). In pursuit of desirable MXene surface, we have developed an in-situ room temperature oxidation process, which resulted in TiO2/MXene nanocomposite and enhanced Li-ion storage. The idea of making metal oxide and MXene nanocomposites was taken to the next level by combining a high capacity anode materials – SnO2 – and MXene. By taking advantage of already existing surface functional groups (–OH), we have developed a composite of SnO2/MXene by atomic layer deposition (ALD) which showed enhanced capacity and excellent cyclic stability. Thermal annealing of MXene at elevated temperature under different atmospheres was

  17. Development of gastrointestinal surface. VIII. Lectin identification of carbohydrate differences

    International Nuclear Information System (INIS)

    Pang, K.Y.; Bresson, J.L.; Walker, W.A.

    1987-01-01

    Binding of microvillus membranes (MVM) from newborn and adult rats by concanavalin A (Con A), Ulex europaeus (UEA I), Dolichos bifluorus (DBA), and Triticum vulgaris (WGA) was examined to determine the availability of carbohydrate-containing sites for these lectins on the intestinal surface during development. Consistent patterns of differences in the reaction of MVM with these lectins were found. Con A and UEA had much higher reactivities to MVM of adult than newborn rats. 125 I-labeled-UEA gel overlay experiments revealed the abundance of UEA-binding sites in MVM of adult rat in contrast to the two binding sites in MVM of a newborn rat. DBA bound only to MVM of the adults, and very few binding sites were found in immature MVM. In contrast to these lectins, WGA binding was much higher in MVM of the newborns and decreased with maturation. Additional experiments on the age dependence of UEA and DBA reactivities revealed that the most striking changes occur in animals from 2 to 2 wk of age. In MVM from 2-wk-old rats, there were only 13.9% and < 0.2% of the adult binding capacities for UEA and DBA, respectively. By the time the animals were 4 wk old, the binding capacity for UEA had attained close to the level of the adults, whereas for DBA it reached 71.3% of the adult value. These results provide definite evidence of changes in the intestinal surface during perinatal development

  18. Development of gastrointestinal surface. VIII. Lectin identification of carbohydrate differences

    Energy Technology Data Exchange (ETDEWEB)

    Pang, K.Y.; Bresson, J.L.; Walker, W.A.

    1987-05-01

    Binding of microvillus membranes (MVM) from newborn and adult rats by concanavalin A (Con A), Ulex europaeus (UEA I), Dolichos bifluorus (DBA), and Triticum vulgaris (WGA) was examined to determine the availability of carbohydrate-containing sites for these lectins on the intestinal surface during development. Consistent patterns of differences in the reaction of MVM with these lectins were found. Con A and UEA had much higher reactivities to MVM of adult than newborn rats. /sup 125/I-labeled-UEA gel overlay experiments revealed the abundance of UEA-binding sites in MVM of adult rat in contrast to the two binding sites in MVM of a newborn rat. DBA bound only to MVM of the adults, and very few binding sites were found in immature MVM. In contrast to these lectins, WGA binding was much higher in MVM of the newborns and decreased with maturation. Additional experiments on the age dependence of UEA and DBA reactivities revealed that the most striking changes occur in animals from 2 to 2 wk of age. In MVM from 2-wk-old rats, there were only 13.9% and < 0.2% of the adult binding capacities for UEA and DBA, respectively. By the time the animals were 4 wk old, the binding capacity for UEA had attained close to the level of the adults, whereas for DBA it reached 71.3% of the adult value. These results provide definite evidence of changes in the intestinal surface during perinatal development.

  19. Energy Efficiency of Biogas Produced from Different Biomass Sources

    International Nuclear Information System (INIS)

    Begum, Shahida; Nazri, A H

    2013-01-01

    Malaysia has different sources of biomass like palm oil waste, agricultural waste, cow dung, sewage waste and landfill sites, which can be used to produce biogas and as a source of energy. Depending on the type of biomass, the biogas produced can have different calorific value. At the same time the energy, being used to produce biogas is dependent on transportation distance, means of transportation, conversion techniques and for handling of raw materials and digested residues. An energy systems analysis approach based on literature is applied to calculate the energy efficiency of biogas produced from biomass. Basically, the methodology is comprised of collecting data, proposing locations and estimating the energy input needed to produce biogas and output obtained from the generated biogas. The study showed that palm oil and municipal solid waste is two potential sources of biomass. The energy efficiency of biogas produced from palm oil residues and municipal solid wastes is 1.70 and 3.33 respectively. Municipal solid wastes have the higher energy efficiency due to less transportation distance and electricity consumption. Despite the inherent uncertainties in the calculations, it can be concluded that the energy potential to use biomass for biogas production is a promising alternative.

  20. The calculation of surface free energy based on embedded atom method for solid nickel

    International Nuclear Information System (INIS)

    Luo Wenhua; Hu Wangyu; Su Kalin; Liu Fusheng

    2013-01-01

    Highlights: ► A new solution for accurate prediction of surface free energy based on embedded atom method was proposed. ► The temperature dependent anisotropic surface energy of solid nickel was obtained. ► In isotropic environment, the approach does not change most predictions of bulk material properties. - Abstract: Accurate prediction of surface free energy of crystalline metals is a challenging task. The theory calculations based on embedded atom method potentials often underestimate surface free energy of metals. With an analytical charge density correction to the argument of the embedding energy of embedded atom method, an approach to improve the prediction for surface free energy is presented. This approach is applied to calculate the temperature dependent anisotropic surface energy of bulk nickel and surface energies of nickel nanoparticles, and the obtained results are in good agreement with available experimental data.

  1. Effects of O2 and H2O plasma immersion ion implantation on surface chemical composition and surface energy of poly vinyl chloride

    International Nuclear Information System (INIS)

    Zhang Wei; Chu, Paul K.; Ji Junhui; Zhang, Yihe; Jiang Zhimin

    2006-01-01

    Oxygen and water plasma immersion ion implantation (PIII) was used to modify poly vinyl chloride (PVC) to enhance oxygen-containing surface functional groups for more effective grafting. The modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and contact angle measurements. Our experimental results show that both oxygen and water PIII can greatly improve the O to C ratios on the surface. The optimal plasma processing conditions differ for the two treatments. The hydrophilicity and surface energy of the plasma-implanted PVC are also improved significantly. Our results indicate that O 2 and H 2 O PIII increase both the polar and dispersion interactions and consequently the surface energy. It can be explained by the large amount of oxygen introduced to the surface and that many C-C bonds are transformed into more polar oxygen containing functional groups

  2. Nuclear momentum distribution and potential energy surface in hexagonal ice

    Science.gov (United States)

    Lin, Lin; Morrone, Joseph; Car, Roberto; Parrinello, Michele

    2011-03-01

    The proton momentum distribution in ice Ih has been recently measured by deep inelastic neutron scattering and calculated from open path integral Car-Parrinello simulation. Here we report a detailed investigation of the relation between momentum distribution and potential energy surface based on both experiment and simulation results. The potential experienced by the proton is largely harmonic and characterized by 3 principal frequencies, which can be associated to weighted averages of phonon frequencies via lattice dynamics calculations. This approach also allows us to examine the importance of quantum effects on the dynamics of the oxygen nuclei close to the melting temperature. Finally we quantify the anharmonicity that is present in the potential acting on the protons. This work is supported by NSF and by DOE.

  3. Computing conformational free energy differences in explicit solvent: An efficient thermodynamic cycle using an auxiliary potential and a free energy functional constructed from the end points.

    Science.gov (United States)

    Harris, Robert C; Deng, Nanjie; Levy, Ronald M; Ishizuka, Ryosuke; Matubayasi, Nobuyuki

    2017-06-05

    Many biomolecules undergo conformational changes associated with allostery or ligand binding. Observing these changes in computer simulations is difficult if their timescales are long. These calculations can be accelerated by observing the transition on an auxiliary free energy surface with a simpler Hamiltonian and connecting this free energy surface to the target free energy surface with free energy calculations. Here, we show that the free energy legs of the cycle can be replaced with energy representation (ER) density functional approximations. We compute: (1) The conformational free energy changes for alanine dipeptide transitioning from the right-handed free energy basin to the left-handed basin and (2) the free energy difference between the open and closed conformations of β-cyclodextrin, a "host" molecule that serves as a model for molecular recognition in host-guest binding. β-cyclodextrin contains 147 atoms compared to 22 atoms for alanine dipeptide, making β-cyclodextrin a large molecule for which to compute solvation free energies by free energy perturbation or integration methods and the largest system for which the ER method has been compared to exact free energy methods. The ER method replaced the 28 simulations to compute each coupling free energy with two endpoint simulations, reducing the computational time for the alanine dipeptide calculation by about 70% and for the β-cyclodextrin by > 95%. The method works even when the distribution of conformations on the auxiliary free energy surface differs substantially from that on the target free energy surface, although some degree of overlap between the two surfaces is required. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  4. High Accuracy Potential Energy Surface, Dipole Moment Surface, Rovibrational Energies and Line List Calculations for ^{14}NH_3

    Science.gov (United States)

    Coles, Phillip; Yurchenko, Sergei N.; Polyansky, Oleg; Kyuberis, Aleksandra; Ovsyannikov, Roman I.; Zobov, Nikolay Fedorovich; Tennyson, Jonathan

    2017-06-01

    We present a new spectroscopic potential energy surface (PES) for ^{14}NH_3, produced by refining a high accuracy ab initio PES to experimental energy levels taken predominantly from MARVEL. The PES reproduces 1722 matched J=0-8 experimental energies with a root-mean-square error of 0.035 cm-1 under 6000 cm^{-1} and 0.059 under 7200 cm^{-1}. In conjunction with a new DMS calculated using multi reference configuration interaction (MRCI) and H=aug-cc-pVQZ, N=aug-cc-pWCVQZ basis sets, an infrared (IR) line list has been computed which is suitable for use up to 2000 K. The line list is used to assign experimental lines in the 7500 - 10,500 cm^{-1} region and previously unassigned lines in HITRAN in the 6000-7000 cm^{-1} region. Oleg L. Polyansky, Roman I. Ovsyannikov, Aleksandra A. Kyuberis, Lorenzo Lodi, Jonathan Tennyson, Andrey Yachmenev, Sergei N. Yurchenko, Nikolai F. Zobov, J. Mol. Spec., 327 (2016) 21-30 Afaf R. Al Derzia, Tibor Furtenbacher, Jonathan Tennyson, Sergei N. Yurchenko, Attila G. Császár, J. Quant. Spectrosc. Rad. Trans., 161 (2015) 117-130

  5. Performance of five surface energy balance models for estimating daily evapotranspiration in high biomass sorghum

    Science.gov (United States)

    Wagle, Pradeep; Bhattarai, Nishan; Gowda, Prasanna H.; Kakani, Vijaya G.

    2017-06-01

    Robust evapotranspiration (ET) models are required to predict water usage in a variety of terrestrial ecosystems under different geographical and agrometeorological conditions. As a result, several remote sensing-based surface energy balance (SEB) models have been developed to estimate ET over large regions. However, comparison of the performance of several SEB models at the same site is limited. In addition, none of the SEB models have been evaluated for their ability to predict ET in rain-fed high biomass sorghum grown for biofuel production. In this paper, we evaluated the performance of five widely used single-source SEB models, namely Surface Energy Balance Algorithm for Land (SEBAL), Mapping ET with Internalized Calibration (METRIC), Surface Energy Balance System (SEBS), Simplified Surface Energy Balance Index (S-SEBI), and operational Simplified Surface Energy Balance (SSEBop), for estimating ET over a high biomass sorghum field during the 2012 and 2013 growing seasons. The predicted ET values were compared against eddy covariance (EC) measured ET (ETEC) for 19 cloud-free Landsat image. In general, S-SEBI, SEBAL, and SEBS performed reasonably well for the study period, while METRIC and SSEBop performed poorly. All SEB models substantially overestimated ET under extremely dry conditions as they underestimated sensible heat (H) and overestimated latent heat (LE) fluxes under dry conditions during the partitioning of available energy. METRIC, SEBAL, and SEBS overestimated LE regardless of wet or dry periods. Consequently, predicted seasonal cumulative ET by METRIC, SEBAL, and SEBS were higher than seasonal cumulative ETEC in both seasons. In contrast, S-SEBI and SSEBop substantially underestimated ET under too wet conditions, and predicted seasonal cumulative ET by S-SEBI and SSEBop were lower than seasonal cumulative ETEC in the relatively wetter 2013 growing season. Our results indicate the necessity of inclusion of soil moisture or plant water stress

  6. Comparison of tropical and subtropical glacier surface energy balance in Africa and South America

    Science.gov (United States)

    Nicholson, L.; Prinz, R.; Kinnard, C.; Mölg, T.; Winkler, M.; Kaser, G.

    2010-05-01

    Tropical glaciers exist only at high altitude, and meteorological and surface energy balance studies of these glaciers can tell us much about the conditions and changes occurring in the mid troposphere. Understanding the surface energy balance and resultant mass balance regime of tropical glaciers is prerequisite to predicting glacier evolution, and future meltwater contributions to local hydrological resources, in response to future climate scenarios. Tropical glacier mass balance variability is strongly linked to precipitation and, via this, to multi-annual climate oscillations such as ENSO and IOZM, so it is useful to understand what role these differing regional influences play in comparison to the similarities imposed by the overarching tropical climate conditions and seasonality. New surface energy balance and mass balance data is available from Lewis glacier (Kenya, 0°09' S; 37°18' E), and here we use an energy and mass balance model to determine the surface energy flux characteristics at this site through a wet and dry season. Results are compared with those from Kersten glacier (Tanzania, 3°04' S; 37°21' E) to understand how conditions at these two glaciers compare and thus what coherent and contrasting climatic information glaciological records from these two sites can be expected to deliver. Meteorological data available from glacier stations on Antizana (Ecuador, 0°25' S; 78°09' W), Artesonraju (Peru, 8°28' S; 77°38' W) Zongo (Bolivia, 16°39' S; 67°47' W) and Guanaco (Chile, 29°20' S; 70°00' W) glaciers in South America offer the opportunity to examine how the surface fluxes and seasonal variability of the energy balance compares to those of the African glaciers. We include the extra-tropical Chilean example for comparison with the similarly high altitude, cold ice of Kersten glacier.

  7. Strength and failure analysis of composite-to-composite adhesive bonds with different surface treatments

    Science.gov (United States)

    Paranjpe, Nikhil; Alamir, Mohammed; Alonayni, Abdullah; Asmatulu, Eylem; Rahman, Muhammad M.; Asmatulu, Ramazan

    2018-03-01

    Adhesives are widely utilized materials in aviation, automotive, energy, defense, and marine industries. Adhesive joints are gradually supplanting mechanical fasteners because they are lightweight structures, thus making the assembly lighter and easier. They also act as a sealant to prevent a structural joint from galvanic corrosion and leakages. Adhesive bonds provide high joint strength because of the fact that the load is distributed uniformly on the joint surface, while in mechanical joints, the load is concentrated at one point, thus leading to stress at that point and in turn causing joint failures. This research concentrated on the analysis of bond strength and failure loads in adhesive joint of composite-to-composite surfaces. Different durations of plasma along with the detergent cleaning were conducted on the composite surfaces prior to the adhesive applications and curing processes. The joint strength of the composites increased about 34% when the surface was plasma treated for 12 minutes. It is concluded that the combination of different surface preparations, rather than only one type of surface treatment, provides an ideal joint quality for the composites.

  8. Specific grinding energy and surface roughness of nanoparticle jet minimum quantity lubrication in grinding

    Directory of Open Access Journals (Sweden)

    Zhang Dongkun

    2015-04-01

    Full Text Available Nanoparticles with the anti-wear and friction reducing features were applied as cooling lubricant in the grinding fluid. Dry grinding, flood grinding, minimal quantity of lubrication (MQL, and nanoparticle jet MQL were used in the grinding experiments. The specific grinding energy of dry grinding, flood grinding and MQL were 84, 29.8, 45.5 J/mm3, respectively. The specific grinding energy significantly decreased to 32.7 J/mm3 in nanoparticle MQL. Compared with dry grinding, the surface roughness values of flood grinding, MQL, and nanoparticle jet MQL were significantly reduced with the surface topography profile values reduced by 11%, 2.5%, and 10%, respectively, and the ten point height of microcosmic unflatness values reduced by 1.5%, 0.5%, and 1.3%, respectively. These results verified the satisfactory lubrication effects of nanoparticle MQL. MoS2, carbon nanotube (CNT, and ZrO2 nanoparticles were also added in the grinding fluid of nanoparticle jet MQL to analyze their grinding surface lubrication effects. The specific grinding energy of MoS2 nanoparticle was only 32.7 J/mm3, which was 8.22% and 10.39% lower than those of the other two nanoparticles. Moreover, the surface roughness of workpiece was also smaller with MoS2 nanoparticle, which indicated its remarkable lubrication effects. Furthermore, the role of MoS2 particles in the grinding surface lubrication at different nanoparticle volume concentrations was analyzed. MoS2 volume concentrations of 1%, 2%, and 3% were used. Experimental results revealed that the specific grinding energy and the workpiece surface roughness initially increased and then decreased as MoS2 nanoparticle volume concentration increased. Satisfactory grinding surface lubrication effects were obtained with 2% MoS2 nanoparticle volume concentration.

  9. Optimal selection among different domestic energy consumption patterns based on energy and exergy analysis

    International Nuclear Information System (INIS)

    Lu, S.; Wu, J.Y.

    2010-01-01

    In China market, people have many choices for air conditioning of their apartments, including heat-pump systems or gas-fired boilers for heating and air conditioners for cooling. Domestic hot water is usually provided by domestic water heaters making use of electricity or natural gas, which are known for their great energy costs. These systems consume much energy and increase the total cost of required domestic energy. A novel system combining heat pump with water heater is proposed in this paper, and it is named domestic energy system. The system can realize the provision of space heating, cooling and domestic hot water throughout a year. Based on different types of air conditioners, space heating equipments and water heaters, domestic energy consumption patterns are concluded to be eight categories. This study describes and compares the eight domestic energy consumption patterns by economic analysis and prime energy analysis method. Results show that the domestic energy system can provide good economy and save energy significantly. Furthermore, exergy analysis method is employed to compare the exergy efficiencies of different energy consumption systems. The results show that the domestic energy system has the highest energy conversion efficiency and can make remarkable contribution to social energy saving.

  10. Self-energy behavior away from the Fermi surface in doped Mott insulators.

    Science.gov (United States)

    Merino, J; Gunnarsson, O; Kotliar, G

    2016-02-03

    We analyze self-energies of electrons away from the Fermi surface in doped Mott insulators using the dynamical cluster approximation to the Hubbard model. For large onsite repulsion, U, and hole doping, the magnitude of the self-energy for imaginary frequencies at the top of the band ([Formula: see text]) is enhanced with respect to the self-energy magnitude at the bottom of the band ([Formula: see text]). The self-energy behavior at these two [Formula: see text]-points is switched for electron doping. Although the hybridization is much larger for (0, 0) than for [Formula: see text], we demonstrate that this is not the origin of this difference. Isolated clusters under a downward shift of the chemical potential, [Formula: see text], at half-filling reproduce the overall self-energy behavior at (0, 0) and [Formula: see text] found in low hole doped embedded clusters. This happens although there is no change in the electronic structure of the isolated clusters. Our analysis shows that a downward shift of the chemical potential which weakly hole dopes the Mott insulator can lead to a large enhancement of the [Formula: see text] self-energy for imaginary frequencies which is not associated with electronic correlation effects, even in embedded clusters. Interpretations of the strength of electronic correlations based on self-energies for imaginary frequencies are, in general, misleading for states away from the Fermi surface.

  11. Effect of dietary dilution of energy and nutrients during different ...

    African Journals Online (AJOL)

    A completely randomized design was conducted to evaluate the effect of dietary dilution of energy and nutrients during different growing periods on compensatory growth of Ross broilers. Four replicant pens were assigned per seven treatments. Chicks in each treatment received concentrated and diluted diets in different ...

  12. Sex differences of human cortical blood flow and energy metabolism.

    Science.gov (United States)

    Aanerud, Joel; Borghammer, Per; Rodell, Anders; Jónsdottir, Kristjana Y; Gjedde, Albert

    2017-07-01

    Brain energy metabolism is held to reflect energy demanding processes in neuropil related to the density and activity of synapses. There is recent evidence that men have higher density of synapses in temporal cortex than women. One consequence of these differences would be different rates of cortical energy turnover and blood flow in men and women. To test the hypotheses that rates of oxygen consumption (CMRO 2 ) and cerebral blood flow are higher in men than in women in regions of cerebral cortex, and that the differences persist with aging, we used positron emission tomography to determine cerebral blood flow and cerebral metabolic rate of oxygen as functions of age in healthy volunteers of both sexes. Cerebral metabolic rate of oxygen did not change with age for either sex and there were no differences of mean values of cerebral metabolic rate of oxygen between men and women in cerebral cortex. Women had significant decreases of cerebral blood flow as function of age in frontal and parietal lobes. Young women had significantly higher cerebral blood flow than men in frontal and temporal lobes, but these differences had disappeared at age 65. The absent sex difference of cerebral energy turnover suggests that the known differences of synaptic density between the sexes are counteracted by opposite differences of individual synaptic activity.

  13. A review of different strategies for HVAC energy saving

    International Nuclear Information System (INIS)

    Vakiloroaya, Vahid; Samali, Bijan; Fakhar, Ahmad; Pishghadam, Kambiz

    2014-01-01

    Highlights: • Various strategies for HVAC energy saving are described and reviewed. • The influence of each strategy on the HVAC energy saving is investigated. • Combination of existing air conditioning technologies appears to be effective for the energy conservation and comfort. • A comparison study between these approaches is carried out. • Changing the HVAC configuration has the potential to increase or reduce energy savings, depending on several factors. - Abstract: Decreasing the energy consumption of heating, ventilation and air conditioning (HVAC) systems is becoming increasingly important due to rising cost of fossil fuels and environmental concerns. Therefore, finding novel ways to reduce energy consumption in buildings without compromising comfort and indoor air quality is an ongoing research challenge. One proven way of achieving energy efficiency in HVAC systems is to design systems that use novel configurations of existing system components. Each HVAC discipline has specific design requirements and each presents opportunities for energy savings. Energy efficient HVAC systems can be created by re-configuring traditional systems to make more strategic use of existing system parts. Recent research has demonstrated that a combination of existing air conditioning technologies can offer effective solutions for energy conservation and thermal comfort. This paper investigates and reviews the different technologies and approaches, and demonstrates their ability to improve the performance of HVAC systems in order to reduce energy consumption. For each strategy, a brief description is first presented and then by reviewing the previous studies, the influence of that method on the HVAC energy saving is investigated. Finally, a comparison study between these approaches is carried out

  14. A metamaterial electromagnetic energy rectifying surface with high harvesting efficiency

    Directory of Open Access Journals (Sweden)

    Xin Duan

    2016-12-01

    Full Text Available A novel metamaterial rectifying surface (MRS for electromagnetic energy capture and rectification with high harvesting efficiency is presented. It is fabricated on a three-layer printed circuit board, which comprises an array of periodic metamaterial particles in the shape of mirrored split rings, a metal ground, and integrated rectifiers employing Schottky diodes. Perfect impedance matching is engineered at two interfaces, i.e. one between free space and the surface, and the other between the metamaterial particles and the rectifiers, which are connected through optimally positioned vias. Therefore, the incident electromagnetic power is captured with almost no reflection by the metamaterial particles, then channeled maximally to the rectifiers, and finally converted to direct current efficiently. Moreover, the rectifiers are behind the metal ground, avoiding the disturbance of high power incident electromagnetic waves. Such a MRS working at 2.45 GHz is designed, manufactured and measured, achieving a harvesting efficiency up to 66.9% under an incident power density of 5 mW/cm2, compared with a simulated efficiency of 72.9%. This high harvesting efficiency makes the proposed MRS an effective receiving device in practical microwave power transmission applications.

  15. A metamaterial electromagnetic energy rectifying surface with high harvesting efficiency

    Science.gov (United States)

    Duan, Xin; Chen, Xing; Zhou, Lin

    2016-12-01

    A novel metamaterial rectifying surface (MRS) for electromagnetic energy capture and rectification with high harvesting efficiency is presented. It is fabricated on a three-layer printed circuit board, which comprises an array of periodic metamaterial particles in the shape of mirrored split rings, a metal ground, and integrated rectifiers employing Schottky diodes. Perfect impedance matching is engineered at two interfaces, i.e. one between free space and the surface, and the other between the metamaterial particles and the rectifiers, which are connected through optimally positioned vias. Therefore, the incident electromagnetic power is captured with almost no reflection by the metamaterial particles, then channeled maximally to the rectifiers, and finally converted to direct current efficiently. Moreover, the rectifiers are behind the metal ground, avoiding the disturbance of high power incident electromagnetic waves. Such a MRS working at 2.45 GHz is designed, manufactured and measured, achieving a harvesting efficiency up to 66.9% under an incident power density of 5 mW/cm2, compared with a simulated efficiency of 72.9%. This high harvesting efficiency makes the proposed MRS an effective receiving device in practical microwave power transmission applications.

  16. Quasilocal energy and surface geometry of Kerr spacetime

    Science.gov (United States)

    Yu, Chengjie; Liu, Jian-Liang

    2017-04-01

    We study the quasilocal energy (QLE) and the surface geometry for Kerr spacetime in the Boyer-Lindquist coordinates without taking the slow rotation approximation. We also consider in the region r ≤2 m , which is inside the ergosphere. For a certain region, r >rk(a ) , the Gaussian curvature of the surface with constant t , r is positive, and for r >√{3 }a the critical value of the QLE is positive. We found that the three curves: the outer horizon r =r+(a ), r =rk(a ) and r =√{3 }a intersect at the point a =√{3 }m /2 , which is the limit for the horizon to be isometrically embedded into R3. The numerical result indicates that the Kerr QLE is monotonically decreasing to the ADM m from the region inside the ergosphere to large r . Based on the second law of black hole dynamics, the QLE is increasing with respect to the irreducible mass Mir. From the results of Chen-Wang-Yau, we conclude that in a certain region, r >rh(a ), the critical value of the Kerr QLE is a global minimum.

  17. Energy-separated sequential irradiation for ripple pattern tailoring on silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Tanuj [Department of Physics, Central University of Haryana, Jant-Pali, Mahendergarh 1123029 (India); Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Kumar, Manish, E-mail: manishbharadwaj@gmail.com [Department of Physics, Central University of Rajasthan, Kishangarh 305801 (India); Panchal, Vandana [Department of Physics, National Institute of Technology, Kurukshetra 136119 (India); Sahoo, P.K. [School of Physical Sciences, National Institute of Science Education and Research, Bhubaneswar 751005 (India); Kanjilal, D. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

    2015-12-01

    Highlights: • A new process for controlling the near-surface amorphization of ripples on Si surfaces. • Ripples generation by 100 KeV Ar{sup +} and amorphization control by 60 KeV Ar{sup +} irradiation. • Advantage of energy-separated irradiation demonstrated by detailed RBS and AFM studies. • Relevant mechanism is presented on the basis of DAMAGE and SIMNRA simulations. • Key role of solid flow towards the amorphous/crystalline interface is demonstrated. - Abstract: Nanoscale ripples on semiconductor surfaces have potential application in biosensing and optoelectronics, but suffer from uncontrolled surface-amorphization when prepared by conventional ion-irradiation methods. A two-step, energy-separated sequential-irradiation enables simultaneous control of surface-amorphization and ripple-dimensions on Si(1 0 0). The evolution of ripples using 100 keV Ar{sup +} bombardment and further tuning of the patterns using a sequential-irradiation by 60 keV Ar{sup +} at different fluences are demonstrated. The advantage of this approach as opposed to increased fluence at the same energy is clarified by atomic force microscopy and Rutherford backscattering spectroscopy investigations. The explanation of our findings is presented through DAMAGE simulation.

  18. Crystallization of glass-forming liquids: Specific surface energy

    International Nuclear Information System (INIS)

    Schmelzer, Jürn W. P.; Abyzov, Alexander S.

    2016-01-01

    A generalization of the Stefan-Skapski-Turnbull relation for the melt-crystal specific interfacial energy is developed in terms of the generalized Gibbs approach extending its standard formulation to thermodynamic non-equilibrium states. With respect to crystal nucleation, this relation is required in order to determine the parameters of the critical crystal clusters being a prerequisite for the computation of the work of critical cluster formation. As one of its consequences, a relation for the dependence of the specific surface energy of critical clusters on temperature and pressure is derived applicable for small and moderate deviations from liquid-crystal macroscopic equilibrium states. Employing the Stefan-Skapski-Turnbull relation, general expressions for the size and the work of formation of critical crystal clusters are formulated. The resulting expressions are much more complex as compared to the respective relations obtained via the classical Gibbs theory. Latter relations are retained as limiting cases of these more general expressions for moderate undercoolings. By this reason, the formulated, here, general relations for the specification of the critical cluster size and the work of critical cluster formation give a key for an appropriate interpretation of a variety of crystallization phenomena occurring at large undercoolings which cannot be understood in terms of the Gibbs’ classical treatment.

  19. Influência de diferentes superfícies na temperatura e no fluxo de energiaInfluência de diferentes superfícies na temperatura e no fluxo de energia: um ensaio experimental / Influence of different surfaces on the temperature and energy flux: an experimental trial

    Directory of Open Access Journals (Sweden)

    Elis Dener Lima Alves

    2012-04-01

    Full Text Available ResumoO meio urbano tem apresentado sérios problemas ambientais os quais prejudicam a qualidade de vida das pessoas. Um dos problemas mais relatados se refere às altas temperaturas registradas nas cidades. Dessa maneira, o objetivo deste trabalho foi analisar a variabilidade da temperatura superficial e o fluxo de energia em diferentes tipos de uso do solo no meio urbano. Para tanto, utilizou-se de um termômetro infravermelho (TD-920 para a medição da temperatura superficial de seis tipos de superfícies. As medições foram realizadas de hora em hora, em um período de 24 horas. Além da temperatura, foram observadas a nebulosidade, os tipos de nuvens e a ausência ou não de precipitação. Os resultados mostraram que as nuvens, a nebulosidade e a precipitação têm influência direta nos padrões da temperatura e do fluxo de energia. Notou-se que as superfícies artificiais (asfalto e concreto apresentaram os maiores valores térmicos e os maiores fluxos de energia, enquanto que superfícies naturais (grama e solo nu apresentaram os menores valores, tendo o asfalto apresentado, em média, 12% a mais de emissão de energia em relação à grama. Portanto, ressalta-se a urgente necessidade de se repensar o uso dos materiais urbanos, para uma melhor qualidade de vida das pessoas.AbstractThe urban environment has presented serious environmental problems which affects the our quality of life. One of the most reported issues refers to the high temperatures recorded in cities. Thus, this study aimed to analyze the variability of surface temperature and the energy flux in different types of land use in urban areas. For this, we used an infrared thermometer (TD-920 in order to measure the surface temperature on six different types of earth surfaces. All the measurements were made every hour over a period of 24 hours. In addition to temperature were observed cloud cover, cloud types, and absence of precipitation. The results showed that the

  20. Determination of surface energies of hot-melt extruded sugar-starch pellets.

    Science.gov (United States)

    Yeung, Chi-Wah; Rein, Hubert

    2018-02-01

    Hot-melt extruded sugar-starch pellets are an alternative for commercial sugar spheres, but their coating properties remain to be studied. Both the European Pharmcopoeia 8.6 and the United States Pharmacopoeia 40 specify the composition of sugar-starch pellets without giving requirements for the manufacturing process. Due to various fabrication techniques, the physicochemical properties of pellets may differ. Therefore, the adhesion energies of three coating dispersions (sustained, enteric and immediate release) on different types of pellets were investigated. In this context, the surface energies of various kinds of corn starch (normal, waxy, high-amylose) and sucrose pellets were analyzed using the sessile drop method, whereas the surface tensions of the coating dispersions were examined using the pendant drop method. The adhesion forces were calculated from the results of these studies. Furthermore, sugar spheres were characterized in terms of particle size distribution, porosity and specific surface area. An increase of the pellets' sucrose content leads to a more porous surface structure, which gives them an enhanced wetting behavior with coating dispersions. The adhesion energies of extruded sugar-starch pellets are similar to those of commercial sugar spheres, which comply with pharmacopeial requirements. Both types of pellets are equally suited for coating.

  1. Nitrogen ion induced nitridation of Si(111) surface: Energy and fluence dependence

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Praveen [Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India); ISOM, Universidad Politecnia de Madrid, 28040 (Spain); Kumar, Mahesh [Physics and Energy Harvesting Group, National Physical Laboratory, New Delhi 110012 (India); Nötzel, R. [ISOM, Universidad Politecnia de Madrid, 28040 (Spain); Shivaprasad, S.M., E-mail: smsprasad@jncasr.ac.in [Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)

    2014-06-01

    We present the surface modification of Si(111) into silicon nitride by exposure to energetic N{sub 2}{sup +} ions. In-situ UHV experiments have been performed to optimize the energy and fluence of the N{sub 2}{sup +} ions to form silicon nitride at room temperature (RT) and characterized in-situ by X-ray photoelectron spectroscopy. We have used N{sub 2}{sup +} ion beams in the energy range of 0.2–5.0 keV of different fluence to induce surface reactions, which lead to the formation of Si{sub x}N{sub y} on the Si(111) surface. The XPS core level spectra of Si(2p) and N(1s) have been deconvoluted into different oxidation states to extract qualitative information, while survey scans have been used for quantifying of the silicon nitride formation, valence band spectra show that as the N{sub 2}{sup +} ion fluence increases, there is an increase in the band gap. The secondary electron emission spectra region of photoemission is used to evaluate the change in the work function during the nitridation process. The results show that surface nitridation initially increases rapidly with ion fluence and then saturates. - Highlights: • A systematic study for the formation of silicon nitride on Si(111). • Investigation of optimal energy and fluence for energetic N{sub 2}{sup +} ions. • Silicon nitride formation at room temperature on Si(111)

  2. Trajectory resolved analysis of LEIS energy spectra: Neutralization and surface structure

    International Nuclear Information System (INIS)

    Beikler, Robert; Taglauer, Edmund

    2001-01-01

    For a quantitative evaluation of low-energy ion scattering (LEIS) data with respect to surface composition and structure a detailed analysis of the energy spectra is required. This includes the identification of multiple scattering processes and the determination of ion survival probabilities. We analyzed scattered ion energy spectra by using the computer code MARLOWE for which we developed a new analysis routine that allows to record energy distributions in dependence of the number of projectile-target atom collisions, in dependence of the distance of closest approach, or in dependence of the scattering crystalline layer. This procedure also permits the determination of ion survival probabilities by applying simple collision-dependent neutralization models. Experimental energy spectra for various projectile (He + , Ne + , Na + ) and target (transition metals, oxides) combinations are well reproduced and quantitative results for ion survival probabilities are obtained. These are largely in agreement with results obtained for bimetallic crystal surfaces obtained in a different way. Such MARLOWE calculations are also useful for the identification of structure relevant processes. This is shown exemplarily for the reconstructed Au(1 1 0) surface including a possibility to determine the (1x2)→(1x1) transition temperature

  3. Environmental evaluation of different forms of electric energy generation

    International Nuclear Information System (INIS)

    Guena, Ana Maria de Oliveira; Aquino, Afonso Rodrigues de

    2007-01-01

    The development and implementation of other forms of energy generation caused local changes, where they were installed, giving rise to environmental impacts. This work presents an evaluation about different forms of electrical energy generation and the environmental impacts relative to each one of them. Five forms of electric energy generation were considered: thermoelectric, nuclear, hydroelectric, wind and solar energy. The implementation and the development of the petroleum industry in the world and in Brazil are presented. The geology of the oil, its extraction and quality improvement, besides details of the functioning of three types of thermoelectric power plants - coal, gas and oil - are also discussed. The specific as well as the environmental impacts they have in common are highlighted. The impacts originated from the deactivation of each one of them are also pointed out. Once outlined the environmental impacts from each form of electric energy generation, they were correlated and compared considering the area of the power plant implantation, the generation capacity, the efficiency, the power and the cost per kW. There is no totally clean form of electric energy generation. There is, however, generation without emission of gases responsible for the green house effect. Therefore, all forms of energy generation are important for a country; in other words, the best situation is the diversity of the energy matrix. (author)

  4. Connecting free energy surfaces in implicit and explicit solvent: an efficient method to compute conformational and solvation free energies.

    Science.gov (United States)

    Deng, Nanjie; Zhang, Bin W; Levy, Ronald M

    2015-06-09

    The ability to accurately model solvent effects on free energy surfaces is important for understanding many biophysical processes including protein folding and misfolding, allosteric transitions, and protein–ligand binding. Although all-atom simulations in explicit solvent can provide an accurate model for biomolecules in solution, explicit solvent simulations are hampered by the slow equilibration on rugged landscapes containing multiple basins separated by barriers. In many cases, implicit solvent models can be used to significantly speed up the conformational sampling; however, implicit solvent simulations do not fully capture the effects of a molecular solvent, and this can lead to loss of accuracy in the estimated free energies. Here we introduce a new approach to compute free energy changes in which the molecular details of explicit solvent simulations are retained while also taking advantage of the speed of the implicit solvent simulations. In this approach, the slow equilibration in explicit solvent, due to the long waiting times before barrier crossing, is avoided by using a thermodynamic cycle which connects the free energy basins in implicit solvent and explicit solvent using a localized decoupling scheme. We test this method by computing conformational free energy differences and solvation free energies of the model system alanine dipeptide in water. The free energy changes between basins in explicit solvent calculated using fully explicit solvent paths agree with the corresponding free energy differences obtained using the implicit/explicit thermodynamic cycle to within 0.3 kcal/mol out of ∼3 kcal/mol at only ∼8% of the computational cost. We note that WHAM methods can be used to further improve the efficiency and accuracy of the implicit/explicit thermodynamic cycle.

  5. Radiotherapy high energy surface dose measurements: effects of chamber polarity

    International Nuclear Information System (INIS)

    Cheung, T.; Yu, P.K.N.; Butson, M.J.; Cancer Services, Wollongong, NSW

    2004-01-01

    Full text: The effects of chamber polarity have been investigated for the measurement of 6MV and 18MV x-ray surface dose using a parallel plate ionization chamber. Results have shown that a significant difference in measured ionization is recorded between to polarities at 6MV and 18MV at the phantom surface. A polarity ratio ranging from 1 062 to 1 005 is seen for 6MV x-rays at the phantom surface for field sizes 5cm x 5cm to 40cm x 40cm when comparing positive to negative polarity. These ratios range from 1.024 to 1.004 for 18MV x-rays with the same field sizes. When these charge reading are compared to the D max readings of the same polarity it is found that these polarity effects are minimal for the calculation of percentage dose results with variations being less than 1% of maximum. Copyright (2004) Australasian College of Physical Scientists and Engineers in Medicine

  6. Quantification of surface energy fluxes from a small water body using scintillometry and eddy covariance

    DEFF Research Database (Denmark)

    McGloin, Ryan; McGowan, Hamish; McJannet, David

    2014-01-01

    Accurate quantification of evaporation from small water storages is essential for water management and planning, particularly in water-scarce regions. In order to ascertain suitable methods for direct measurement of evaporation from small water bodies, this study presents a comparison of eddy......% greater than eddy covariance measurements. We suggest possible reasons for this difference and provide recommendations for further research for improving measurements of surface energy fluxes over small water bodies using eddy covariance and scintillometry. Key Points Source areas for Eddy covariance...... and scintillometry were on the water surface Reasonable agreement was shown between the sensible heat flux measurements Scintillometer estimates of latent heat flux were greater than eddy covariance...

  7. Low energy ion scattering as a tool for surface structure and composition analysis

    International Nuclear Information System (INIS)

    Armour, D.G.

    1980-01-01

    Low energy ion scattering is finding increasing application in the study of areas such as gas adsorption, thin film deposition and surface damage creation and annealing during ion irradiation where structural and compositional changes occurring in only the outermost atomic layer need to be monitored. The capabilities of the technique and the ways in which it has been developed for different types of analysis depend strongly on the fundamental atomic collision processes taking place at the surface and it is these processes, together with examples of their role in analysis applications, that form the subject of this paper. (author)

  8. A thermodynamic model for predicting surface melting and overheating of different crystal planes in BCC, FCC and HCP pure metallic thin films

    International Nuclear Information System (INIS)

    Jahangir, Vafa; Riahifar, Reza; Sahba Yaghmaee, Maziar

    2016-01-01

    In order to predict as well as study the surface melting phenomena in contradiction to surface overheating, a generalized thermodynamics model including the surface free energy of solid and the melt state along with the interfacial energy of solid–liquid (melt on substrate) has been introduced. In addition, the effect of different crystal structures of surfaces in fcc, bcc and hcp metals was included in surface energies as well as in the atomistic model. These considerations lead us to predict surface melting and overheating as two contradictory melting phenomena. The results of the calculation are demonstrated on the example of Pb and Al thin films in three groups of (100), (110) and (111) surface planes. Our conclusions show good agreement with experimental results and other theoretical investigations. Moreover, a computational algorithm has been developed which enables users to investigate the surface melt or overheating of single component metallic thin film with variable crystal structures and different crystalline planes. This model and developed software can be used for studying all related surface phenomena. - Highlights: • Investigating the surface melting and overheating phenomena • Effect of crystal orientations, surface energies, geometry and different atomic surface layers • Developing a computational algorithm and its related code (free-software SMSO-Ver1) • Thickness and orientation of surface plane dominate the surface melting or overheating. • Total excess surface energy as a function of thickness and temperature explains melting.

  9. A thermodynamic model for predicting surface melting and overheating of different crystal planes in BCC, FCC and HCP pure metallic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jahangir, Vafa, E-mail: vafa.jahangir@yahoo.com; Riahifar, Reza, E-mail: reza_rfr@yahoo.com; Sahba Yaghmaee, Maziar, E-mail: fkmsahba@uni-miskolc.hu

    2016-03-31

    In order to predict as well as study the surface melting phenomena in contradiction to surface overheating, a generalized thermodynamics model including the surface free energy of solid and the melt state along with the interfacial energy of solid–liquid (melt on substrate) has been introduced. In addition, the effect of different crystal structures of surfaces in fcc, bcc and hcp metals was included in surface energies as well as in the atomistic model. These considerations lead us to predict surface melting and overheating as two contradictory melting phenomena. The results of the calculation are demonstrated on the example of Pb and Al thin films in three groups of (100), (110) and (111) surface planes. Our conclusions show good agreement with experimental results and other theoretical investigations. Moreover, a computational algorithm has been developed which enables users to investigate the surface melt or overheating of single component metallic thin film with variable crystal structures and different crystalline planes. This model and developed software can be used for studying all related surface phenomena. - Highlights: • Investigating the surface melting and overheating phenomena • Effect of crystal orientations, surface energies, geometry and different atomic surface layers • Developing a computational algorithm and its related code (free-software SMSO-Ver1) • Thickness and orientation of surface plane dominate the surface melting or overheating. • Total excess surface energy as a function of thickness and temperature explains melting.

  10. Ab initio study on stacking sequences, free energy, dynamical stability and potential energy surfaces of graphite structures

    International Nuclear Information System (INIS)

    Anees, P; Valsakumar, M C; Chandra, Sharat; Panigrahi, B K

    2014-01-01

    Ab initio simulations have been performed to study the structure, energetics and stability of several plausible stacking sequences in graphite. These calculations suggest that in addition to the standard structures, graphite can also exist in AA-simple hexagonal, AB-orthorhombic and ABC-hexagonal type stacking. The free energy difference between these structures is very small (∼1 meV/atom), and hence all the structures can coexist from purely energetic considerations. Calculated x-ray diffraction patterns are similar to those of the standard structures for 2θ ⩽ 70°. Shear elastic constant C 44 is negative in AA-simple hexagonal, AB-orthorhombic and ABC-hexagonal structures, suggesting that these structures are mechanically unstable. Phonon dispersions show that the frequencies of some modes along the Γ–A direction in the Brillouin zone are imaginary in all of the new structures, implying that these structures are dynamically unstable. Incorporation of zero point vibrational energy via the quasi-harmonic approximation does not result in the restoration of dynamical stability. Potential energy surfaces for the unstable normal modes are seen to have the topography of a potential hill for all the new structures, confirming that all of the new structures are inherently unstable. The fact that the potential energy surface is not in the form of a double well implies that the structures are linearly as well as globally unstable. (paper)

  11. Extracting renewable energy from a salinity difference using a capacitor.

    Science.gov (United States)

    Brogioli, Doriano

    2009-07-31

    Completely renewable energy can be produced by using water solutions of different salinity, like river water and sea water. Many different methods are already known, but development is still at prototype stage. Here I report a novel method, based on electric double-layer capacitor technology. Two porous electrodes, immersed in the salt solution, constitute a capacitor. It is first charged, then the salt solution is brought into contact with fresh water. The electrostatic energy increases as the salt concentration of the solution is reduced due to diffusion. This device can be used to turn sources of salinity difference into completely renewable sources of energy. An experimental demonstration is given, and performances and possible improvements are discussed.

  12. Characterization of gloss properties of differently treated polymer coating surfaces by surface clarity measurement methodology.

    Science.gov (United States)

    Gruber, Dieter P; Buder-Stroisznigg, Michael; Wallner, Gernot; Strauß, Bernhard; Jandel, Lothar; Lang, Reinhold W

    2012-07-10

    With one measurement configuration, existing gloss measurement methodologies are generally restricted to specific gloss levels. A newly developed image-analytical gloss parameter called "clarity" provides the possibility to describe the perceptual result of a broad range of different gloss levels with one setup. In order to analyze and finally monitor the perceived gloss of products, a fast and flexible method also for the automated inspection is highly demanded. The clarity parameter is very fast to calculate and therefore usable for fast in-line surface inspection. Coated metal specimens were deformed by varying degree and polished afterwards in order to study the clarity parameter regarding the quantification of varying surface gloss types and levels. In order to analyze the correlation with the human gloss perception a study was carried out in which experts were asked to assess gloss properties of a series of surface samples under standardized conditions. The study confirmed clarity to exhibit considerably better correlation to the human perception than alternative gloss parameters.

  13. Potential Energy Surface of NO on Pt(997: Adsorbed States and Surface Diffusion

    Directory of Open Access Journals (Sweden)

    N. Tsukahara

    2012-01-01

    Full Text Available The potential energy surface (PES of NO on Pt(997 has been elucidated: the adsorption states and diffusion processes of NO on Pt(997 at low coverage were investigated by using infrared reflection absorption spectroscopy (IRAS and scanning tunneling microscopy (STM. When NO molecules adsorb on a surface at a low temperature (11 K, each molecule transiently migrates on the surface from the first impact point to a possible adsorption site. We found that there are four stable adsorption sites for NO on Pt(997: a bridge site of the upper step, an fcc- (or hcp- hollow site of the terrace, an on-top site of the terrace, and an fcc-hollow site of the lower step. At higher temperatures above 45 K, NO molecules start to migrate thermally to more stable adsorption sites on a terrace, and they are finally trapped at the bridge sites of the step, which are the most stable among the four sites.

  14. Comparing the health and environmental hazards of different energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, L.D.

    1982-01-01

    Energy and environment can pose difficult challenges for policy makers and scientists. Assessing health impacts of different energy sources requires synthesis of research results from many different disciplines into a rational framework. Information is often scanty; qualitatively different risks, or energy systems with quite different end uses, must be put on a common footing. Risk-assessment methods reviewed include examples drawn from work of the Biomedical and Environmental Assessment Division at Brookhaven National Laboratory and elsewhere. Coal and nuclear fuel cycles are compared in respect to morbidity and mortality. Other cycles (oil, gas and renewables) are also examined. In broadening comparisons to include new technologies, one must include the impact of manufacturing the energy-producing devices as part of an expanded fuel cycle, via input-output methods. Input-output analysis allows comparisons of direct and system-wide impacts. Throughout the analysis, uncertainties must be explicitly recognized in the results, including uncertainty in validity of data and uncertainty in choice of appropriate models. No single method of comparative risk assessment is fully satisfactory; each has its limitations. By use of several methods progress has been made in understanding the relative impact of energy technologies.

  15. Comparing the health and environmental hazards of different energy systems

    International Nuclear Information System (INIS)

    Hamilton, L.D.

    1982-01-01

    Energy and environment can pose difficult challenges for policy makers and scientists. Assessing health impacts of different energy sources requires synthesis of research results from many different disciplines into a rational framework. Information is often scanty; qualitatively different risks, or energy systems with quite different end uses, must be put on a common footing. Risk-assessment methods reviewed include examples drawn from work of the Biomedical and Environmental Assessment Division at Brookhaven National Laboratory and elsewhere. Coal and nuclear fuel cycles are compared in respect to morbidity and mortality. Other cycles (oil, gas and renewables) are also examined. In broadening comparisons to include new technologies, one must include the impact of manufacturing the energy-producing devices as part of an expanded fuel cycle, via input-output methods. Input-output analysis allows comparisons of direct and system-wide impacts. Throughout the analysis, uncertainties must be explicitly recognized in the results, including uncertainty in validity of data and uncertainty in choice of appropriate models. No single method of comparative risk assessment is fully satisfactory; each has its limitations. By use of several methods progress has been made in understanding the relative impact of energy technologies

  16. Comparing the health impacts of different energy sources

    International Nuclear Information System (INIS)

    Hamilton, L.D.

    1982-01-01

    Assessing health impacts of different energy sources requires synthesis of research results from many different disciplines into a rational framework. Information is often scanty; qualitatively different risks, or energy systems with substantially different end uses, must be put on a common footing. Historically institutional constraints have inhibited agencies from making incisive intercomparisons necessary for formulating energy policy; this has exacerbated public controversy over appropriate energy sources. Risk assessment methods reviewed include examples drawn from work of the Biomedical and Environmental Assessment Division at Brookhaven National Laboratory and elsewhere. Uncertainty over the mechanism and size of air pollution health damage is addressed through a probabilistic health-damage function, using sulphate-particle exposure as an indicator. This facilitates intercomparison through analysis of each step in the whole fuel cycle between a typical coal and nuclear power plant. Occupational health impacts, a significant fraction of overall damage, are illustrated by accident trends in coal-mining. In broadening comparisons to include new technologies, one must include the impact of manufacturing the energy-producing device as part of an expanded fuel cycle, via input/output methods. Throughout the analysis, uncertainties must be made explicit in the results, including uncertainty of data and uncertainty in choice of appropriate models and methods. No single method of comparative risk assessment is fully satisfactory; each has its limitations. Several methods must be compared if decision-making is to be realistic. (author)

  17. Adhesive bonding of resin composite to various titanium surfaces using different metal conditioners and a surface modification system

    Directory of Open Access Journals (Sweden)

    Hercules Jorge ALMILHATTI

    2013-12-01

    Full Text Available Objective: This study evaluated the effect of three metal conditioners on the shear bond strength (SBS of a prosthetic composite material to cpTi grade I having three surface treatments. Material and Methods: One hundred sixty eight rivet-shaped specimens (8.0x2.0 mm were cast and subjected to polishing (P or sandblasting with either 50 mm (50SB or 250 mm (250SB Al2O3. The metal conditioners Metal Photo Primer (MPP, Cesead II Opaque Primer (OP, Targis Link (TL, and one surface modification system Siloc (S, were applied to the specimen surfaces, which were covered with four 1-mm thick layers of resin composite. The resin layers were exposed to curing light for 90 s separately. Seven specimens from each experimental group were stored in water at 37ºC for 24 h while the other 7 specimens were subjected to 5,000 thermal cycles consisting of water baths at 4ºC and 60ºC (n=7. All specimens were subjected to SBS test (0.5 mm/min until failure occurred, and further 28 specimens were analyzed using scanning electron microscope (SEM and X-ray energy-dispersive spectroscopy (EDS. Data were analyzed by 3-way ANOVA followed by post-hoc Tukey's test (α=0.05. Results: On 50SB surfaces, OP groups showed higher SBS means than MPP (P<0.05, while no significant difference was found among OP, S, and TL groups. On 250SB surfaces, OP and TL groups exhibited higher SBS than MPP and S (P<0.05. No significant difference in SBS was found between OP and TL groups nor between MPP and S groups. The use of conditioners on 250SB surfaces resulted in higher SBS means than the use of the same products on 50SB surfaces (P<0.05. Conclusion: Sandblasting associated with the use of metal conditioners improves SBS of resin composites to cpTi.

  18. Tetrahedral cluster and pseudo molecule: New approaches to Calculate Absolute Surface Energy of Zinc Blende (111)/(-1-1-1) Surface

    Science.gov (United States)

    Zhang, Yiou; Zhang, Jingzhao; Tse, Kinfai; Wong, Lun; Chan, Chunkai; Deng, Bei; Zhu, Junyi

    Determining accurate absolute surface energies for polar surfaces of semiconductors has been a great challenge in decades. Here, we propose pseudo-hydrogen passivation to calculate them, using density functional theory approaches. By calculating the energy contribution from pseudo-hydrogen using either a pseudo molecule method or a tetrahedral cluster method, we obtained (111)/(-1-1-1) surfaces energies of Si, GaP, GaAs, and ZnS with high self-consistency. Our findings may greatly enhance the basic understandings of different surfaces and lead to novel strategies in the crystal growth. We would like to thank Su-huai Wei for helpful discussions. Computing resources were provided by the High Performance Cluster Computing Centre, Hong Kong Baptist University. This work was supported by the start-up funding and direct Grant with the Project.

  19. Fast exploration of an optimal path on the multidimensional free energy surface

    Science.gov (United States)

    Chen, Changjun

    2017-01-01

    In a reaction, determination of an optimal path with a high reaction rate (or a low free energy barrier) is important for the study of the reaction mechanism. This is a complicated problem that involves lots of degrees of freedom. For simple models, one can build an initial path in the collective variable space by the interpolation method first and then update the whole path constantly in the optimization. However, such interpolation method could be risky in the high dimensional space for large molecules. On the path, steric clashes between neighboring atoms could cause extremely high energy barriers and thus fail the optimization. Moreover, performing simulations for all the snapshots on the path is also time-consuming. In this paper, we build and optimize the path by a growing method on the free energy surface. The method grows a path from the reactant and extends its length in the collective variable space step by step. The growing direction is determined by both the free energy gradient at the end of the path and the direction vector pointing at the product. With fewer snapshots on the path, this strategy can let the path avoid the high energy states in the growing process and save the precious simulation time at each iteration step. Applications show that the presented method is efficient enough to produce optimal paths on either the two-dimensional or the twelve-dimensional free energy surfaces of different small molecules. PMID:28542475

  20. Rebound effect of improved energy efficiency for different energy types: A general equilibrium analysis for China

    International Nuclear Information System (INIS)

    Lu, Yingying; Liu, Yu; Zhou, Meifang

    2017-01-01

    This paper explores the rebound effect of different energy types in China based on a static computable general equilibrium model. A one-off 5% energy efficiency improvement is imposed on five different types of energy, respectively, in all the 135 production sectors in China. The rebound effect is measured both on the production level and on the economy-wide level for each type of energy. The results show that improving energy efficiency of using electricity has the largest positive impact on GDP among the five energy types. Inter-fuel substitutability does not affect the macroeconomic results significantly, but long-run impact is usually greater than the short-run impact. For the exports-oriented sectors, those that are capital-intensive get big negative shock in the short run while those that are labour-intensive get hurt in the long run. There is no “backfire” effect; however, improving efficiency of using electricity can cause negative rebound, which implies that improving the energy efficiency of using electricity might be a good policy choice under China's current energy structure. In general, macro-level rebound is larger than production-level rebound. Primary energy goods show larger rebound effect than secondary energy goods. In addition, the paper points out that the policy makers in China should look at the rebound effect in the long term rather than in the short term. The energy efficiency policy would be a good and effective policy choice for energy conservation in China when it still has small inter-fuel substitution. - Highlights: • Primary energy goods show larger rebound effect than secondary energy goods. • Improving efficiency of using electricity can cause negative rebound. • The energy efficiency policy would be an effective policy choice for China. • Policy-makers should consider the rebound effect in the longer term.

  1. Design and fabrication of non silicon substrate based MEMS energy harvester for arbitrary surface applications

    Energy Technology Data Exchange (ETDEWEB)

    Balpande, Suresh S., E-mail: balpandes@rknec.edu [Ph.D.. Scholar, Department of Electronics Engineering Shri Ramdeobaba College of Engineering & Management, Nagpur-13, (M.S.) (India); Pande, Rajesh S. [Professor, Department of Electronics Engineering Shri Ramdeobaba College of Engineering & Management, Nagpur-13, (M.S.) (India)

    2016-04-13

    Internet of Things (IoT) uses MEMS sensor nodes and actuators to sense and control objects through Internet. IOT deploys millions of chemical battery driven sensors at different locations which are not reliable many times because of frequent requirement of charging & battery replacement in case of underground laying, placement at harsh environmental conditions, huge count and difference between demand (24 % per year) and availability (energy density growing rate 8% per year). Energy harvester fabricated on silicon wafers have been widely used in manufacturing MEMS structures. These devices require complex fabrication processes, costly chemicals & clean room. In addition to this silicon wafer based devices are not suitable for curved surfaces like pipes, human bodies, organisms, or other arbitrary surface like clothes, structure surfaces which does not have flat and smooth surface always. Therefore, devices based on rigid silicon wafers are not suitable for these applications. Flexible structures are the key solution for this problems. Energy transduction mechanism generates power from free surrounding vibrations or impact. Sensor nodes application has been purposefully selected due to discrete power requirement at low duty cycle. Such nodes require an average power budget in the range of about 0.1 microwatt to 1 mW over a period of 3-5 seconds. Energy harvester is the best alternate source in contrast with battery for sensor node application. Novel design of Energy Harvester based on cheapest flexible non silicon substrate i.e. cellulose acetate substrate have been modeled, simulated and analyzed on COMSOL multiphysics and fabricated using sol-gel spin coating setup. Single cantilever based harvester generates 60-75 mV peak electric potential at 22Hz frequency and approximately 22 µW power at 1K-Ohm load. Cantilever array can be employed for generating higher voltage by replicating this structure. This work covers design, optimization, fabrication of

  2. Design and fabrication of non silicon substrate based MEMS energy harvester for arbitrary surface applications

    Science.gov (United States)

    Balpande, Suresh S.; Pande, Rajesh S.

    2016-04-01

    Internet of Things (IoT) uses MEMS sensor nodes and actuators to sense and control objects through Internet. IOT deploys millions of chemical battery driven sensors at different locations which are not reliable many times because of frequent requirement of charging & battery replacement in case of underground laying, placement at harsh environmental conditions, huge count and difference between demand (24 % per year) and availability (energy density growing rate 8% per year). Energy harvester fabricated on silicon wafers have been widely used in manufacturing MEMS structures. These devices require complex fabrication processes, costly chemicals & clean room. In addition to this silicon wafer based devices are not suitable for curved surfaces like pipes, human bodies, organisms, or other arbitrary surface like clothes, structure surfaces which does not have flat and smooth surface always. Therefore, devices based on rigid silicon wafers are not suitable for these applications. Flexible structures are the key solution for this problems. Energy transduction mechanism generates power from free surrounding vibrations or impact. Sensor nodes application has been purposefully selected due to discrete power requirement at low duty cycle. Such nodes require an average power budget in the range of about 0.1 microwatt to 1 mW over a period of 3-5 seconds. Energy harvester is the best alternate source in contrast with battery for sensor node application. Novel design of Energy Harvester based on cheapest flexible non silicon substrate i.e. cellulose acetate substrate have been modeled, simulated and analyzed on COMSOL multiphysics and fabricated using sol-gel spin coating setup. Single cantilever based harvester generates 60-75 mV peak electric potential at 22Hz frequency and approximately 22 µW power at 1K-Ohm load. Cantilever array can be employed for generating higher voltage by replicating this structure. This work covers design, optimization, fabrication of harvester and

  3. Design and fabrication of non silicon substrate based MEMS energy harvester for arbitrary surface applications

    International Nuclear Information System (INIS)

    Balpande, Suresh S.; Pande, Rajesh S.

    2016-01-01

    Internet of Things (IoT) uses MEMS sensor nodes and actuators to sense and control objects through Internet. IOT deploys millions of chemical battery driven sensors at different locations which are not reliable many times because of frequent requirement of charging & battery replacement in case of underground laying, placement at harsh environmental conditions, huge count and difference between demand (24 % per year) and availability (energy density growing rate 8% per year). Energy harvester fabricated on silicon wafers have been widely used in manufacturing MEMS structures. These devices require complex fabrication processes, costly chemicals & clean room. In addition to this silicon wafer based devices are not suitable for curved surfaces like pipes, human bodies, organisms, or other arbitrary surface like clothes, structure surfaces which does not have flat and smooth surface always. Therefore, devices based on rigid silicon wafers are not suitable for these applications. Flexible structures are the key solution for this problems. Energy transduction mechanism generates power from free surrounding vibrations or impact. Sensor nodes application has been purposefully selected due to discrete power requirement at low duty cycle. Such nodes require an average power budget in the range of about 0.1 microwatt to 1 mW over a period of 3-5 seconds. Energy harvester is the best alternate source in contrast with battery for sensor node application. Novel design of Energy Harvester based on cheapest flexible non silicon substrate i.e. cellulose acetate substrate have been modeled, simulated and analyzed on COMSOL multiphysics and fabricated using sol-gel spin coating setup. Single cantilever based harvester generates 60-75 mV peak electric potential at 22Hz frequency and approximately 22 µW power at 1K-Ohm load. Cantilever array can be employed for generating higher voltage by replicating this structure. This work covers design, optimization, fabrication of

  4. An intercomparison and validation of satellite-based surface radiative energy flux estimates over the Arctic

    Science.gov (United States)

    Riihelä, Aku; Key, Jeffrey R.; Meirink, Jan Fokke; Kuipers Munneke, Peter; Palo, Timo; Karlsson, Karl-Göran

    2017-05-01

    Accurate determination of radiative energy fluxes over the Arctic is of crucial importance for understanding atmosphere-surface interactions, melt and refreezing cycles of the snow and ice cover, and the role of the Arctic in the global energy budget. Satellite-based estimates can provide comprehensive spatiotemporal coverage, but the accuracy and comparability of the existing data sets must be ascertained to facilitate their use. Here we compare radiative flux estimates from Clouds and the Earth's Radiant Energy System (CERES) Synoptic 1-degree (SYN1deg)/Energy Balanced and Filled, Global Energy and Water Cycle Experiment (GEWEX) surface energy budget, and our own experimental FluxNet / Satellite Application Facility on Climate Monitoring cLoud, Albedo and RAdiation (CLARA) data against in situ observations over Arctic sea ice and the Greenland Ice Sheet during summer of 2007. In general, CERES SYN1deg flux estimates agree best with in situ measurements, although with two particular limitations: (1) over sea ice the upwelling shortwave flux in CERES SYN1deg appears to be underestimated because of an underestimated surface albedo and (2) the CERES SYN1deg upwelling longwave flux over sea ice saturates during midsummer. The Advanced Very High Resolution Radiometer-based GEWEX and FluxNet-CLARA flux estimates generally show a larger range in retrieval errors relative to CERES, with contrasting tendencies relative to each other. The largest source of retrieval error in the FluxNet-CLARA downwelling shortwave flux is shown to be an overestimated cloud optical thickness. The results illustrate that satellite-based flux estimates over the Arctic are not yet homogeneous and that further efforts are necessary to investigate the differences in the surface and cloud properties which lead to disagreements in flux retrievals.

  5. Roughness, surface energy, and superficial damages of CAD/CAM materials after surface treatment.

    Science.gov (United States)

    Strasser, Thomas; Preis, Verena; Behr, Michael; Rosentritt, Martin

    2018-02-05

    The aim of this study was to examine the effects of surface pre-treatment on CAD/CAM materials including ceramics, zirconia, resin-infiltrated ceramic, and resin-based composite. Specimens were made of ten CAD/CAM materials (Celtra Duo, Degudent, D; Vita Suprinity, Vita, D; E.max CAD, Ivoclar-Vivadent, FL; E.max ZirCAD, Ivoclar-Vivadent, FL; Vita Enamic, Vita, D; Cerasmart, GC, B; LAVA Ultimate, 3M, D; SHOFU Block HC, SHOFU, US; Grandio Blocs, VOCO, D; BRILLIANT Crios, Coltene, CH) and pretreated to represent clinical procedures (Hf 20 s/5%; phosphoric acid 20 s/37%; Monobond etch and prime (Ivoclar-Vivadent, FL); water-cooled diamond bur (80 μm; 4 μm); Al 2 O 3 -blasting (50 μm/1 bar, 50 μm/2 bar, 120 μm/1 bar, 120 μm/2 bar); untreated; manufacturer's instructions). SEM-analysis (Phenom, FEI, NL) of the surfaces was performed (magnifications ≤ 10,000×). Roughness values R a , R z (KJ 3D, Keyence, J), and surface energy SE (OCA15 plus, SCA20, DataPhysics, D) were determined (statistics: non-parametric Mann-Whitney U test/Kruskal-Wallis test for independent specimen, α = 0.05). Kruskal-Wallis revealed significant (p CAD/CAM materials require individual pre-treatment for optimized and protective surface activation. Cementation is a key factor for clinical success. Given the variety of available CAD/CAM materials, specific procedures are needed.

  6. Computation of Hemagglutinin Free Energy Difference by the Confinement Method

    Science.gov (United States)

    2017-01-01

    Hemagglutinin (HA) mediates membrane fusion, a crucial step during influenza virus cell entry. How many HAs are needed for this process is still subject to debate. To aid in this discussion, the confinement free energy method was used to calculate the conformational free energy difference between the extended intermediate and postfusion state of HA. Special care was taken to comply with the general guidelines for free energy calculations, thereby obtaining convergence and demonstrating reliability of the results. The energy that one HA trimer contributes to fusion was found to be 34.2 ± 3.4kBT, similar to the known contributions from other fusion proteins. Although computationally expensive, the technique used is a promising tool for the further energetic characterization of fusion protein mechanisms. Knowledge of the energetic contributions per protein, and of conserved residues that are crucial for fusion, aids in the development of fusion inhibitors for antiviral drugs. PMID:29151344

  7. An intercomparison of surface energy flux measurement systems used during FIFE 1987

    International Nuclear Information System (INIS)

    Nie, D.; Kanemasu, E.T.; Fritschen, L.J.; Weaver, H.L.; Smith, E.A.; Verma, S.B.; Field, R.T.; Kustas, W.P.; Stewart, J.B.

    1992-01-01

    During FIFE 1987, surface energy fluxes were measured at 22 flux sites by nine groups of scientists using different measuring systems. A rover Bowen ratio station was taken to 20 of the flux stations to serve as a reference for estimating the instrument-related differences. The rover system was installed within a few meters from the host instrument of a site. Using linear regression analysis, net radiation, Bowen ratio, and latent heat fluxes were compared between the rover measurements and the host measurements. The average differences in net radiation, Bowen ratio, and latent heat flux from different types of instruments can be up to 10, 30, and 20 percent, respectively. The Didcot net radiometer gave higher net radiation while the Swissteco type showed lower values, as compared to the corrected radiation energy balance system (REBS) model. The four-way components method and the Thornthwaite type give similar values to the REBS. The surface energy radiation balance systems type Bowen ratio systems exhibit slightly lower Bowen ratios and thus higher latent heat fluxes, compared to the arid zone evapotranspiration systems. Eddy correlation systems showed slightly lower latent heat flux in comparison to the Bowen ratio systems. It is recommended that users of the flux data take these differences into account. 11 refs

  8. Constructing Potential Energy Surfaces for Polyatomic Systems: Recent Progress and New Problems

    Directory of Open Access Journals (Sweden)

    J. Espinosa-Garcia

    2012-01-01

    Full Text Available Different methods of constructing potential energy surfaces in polyatomic systems are reviewed, with the emphasis put on fitting, interpolation, and analytical (defined by functional forms approaches, based on quantum chemistry electronic structure calculations. The different approaches are reviewed first, followed by a comparison using the benchmark H + CH4 and the H + NH3 gas-phase hydrogen abstraction reactions. Different kinetics and dynamics properties are analyzed for these reactions and compared with the available experimental data, which permits one to estimate the advantages and disadvantages of each method. Finally, we analyze different problems with increasing difficulty in the potential energy construction: spin-orbit coupling, molecular size, and more complicated reactions with several maxima and minima, which test the soundness and general applicability of each method. We conclude that, although the field of small systems, typically atom-diatom, is mature, there still remains much work to be done in the field of polyatomic systems.

  9. Using a thermal-based two source energy balance model with time-differencing to estimate surface energy fluxes with day-night MODIS observations

    DEFF Research Database (Denmark)

    Guzinski, Radoslaw; Anderson, M.C.; Kustas, W.P.

    2013-01-01

    The Dual Temperature Difference (DTD) model, introduced by Norman et al. (2000), uses a two source energy balance modelling scheme driven by remotely sensed observations of diurnal changes in land surface temperature (LST) to estimate surface energy fluxes. By using a time-differential temperature...... agreement with field measurements is obtained for a number of ecosystems in Denmark and the United States. Finally, regional maps of energy fluxes are produced for the Danish Hydrological ObsErvatory (HOBE) in western Denmark, indicating realistic patterns based on land use....

  10. Differences in Energy Capacities between Tennis Players and Runners

    OpenAIRE

    Novak, Dario; Vučetić, Vlatko; Žugaj, Sanja

    2013-01-01

    The primary purpose of this study was to determine differences between elite athletes and tennis players in order to provide a clearer picture regarding the energy demands in modern tennis. Forty-eight (48) athletes and 24 tennis players from Croatian national leagues were compared in morphological and physiological parameters of an all-out incremental treadmill test with gas exchange measurements. Tennis players’ HRmax (192.96±7.75 bpm) shows values that are most different to 400-meters spri...

  11. Energy and Environmental Performance of Bioethanol from Different Lignocelluloses

    Directory of Open Access Journals (Sweden)

    Lin Luo

    2010-01-01

    Full Text Available Climate change and the wish to reduce the dependence on oil are the incentives for the development of alternative energy sources. The use of lignocellulosic biomass together with cellulosic processing technology provides opportunities to produce fuel ethanol with less competition with food and nature. Many studies on energy analysis and life cycle assessment of second-generation bioethanol have been conducted. However, due to the different methodology used and different system boundary definition, it is difficult to compare their results. To permit a direct comparison of fuel ethanol from different lignocelluloses in terms of energy use and environmental impact, seven studies conducted in our group were summarized in this paper, where the same technologies were used to convert biomass to ethanol, the same system boundaries were defined, and the same allocation procedures were followed. A complete set of environmental impacts ranging from global warming potential to toxicity aspects is used. The results provide an overview on the energy efficiency and environmental performance of using fuel ethanol derived from different feedstocks in comparison with gasoline.

  12. Different Reliability Assessment Approaches for Wave Energy Converters

    DEFF Research Database (Denmark)

    Ambühl, Simon; Kramer, Morten Mejlhede; Sørensen, John Dalsgaard

    2015-01-01

    Reliability assessments are of importance for wave energy converters (WECs) due to the fact that accessibility might be limited in case of failure and maintenance. These failure rates can be adapted by reliability considerations. There are two different approaches to how reliability can...

  13. Dose distribution considerations of medium energy electron beams at extended source-to-surface distance

    International Nuclear Information System (INIS)

    Saw, Cheng B.; Ayyangar, Komanduri M.; Pawlicki, Todd; Korb, Leroy J.

    1995-01-01

    Purpose: To determine the effects of extended source-to-surface distance (SSD) on dose distributions for a range of medium energy electron beams and cone sizes. Methods and Materials: The depth-dose curves and isodose distributions of 6 MeV, 10 MeV, and 14 MeV electron beams from a dual photon and multielectron energies linear accelerator were studied. To examine the influence of cone size, the smallest and the largest cone sizes available were used. Measurements were carried out in a water phantom with the water surface set at three different SSDs from 101 to 116 cm. Results: In the region between the phantom surface and the depth of maximum dose, the depth-dose decreases as the SSD increases for all electron beam energies. The effects of extended SSD in the region beyond the depth of maximum dose are unobservable and, hence, considered minimal. Extended SSD effects are apparent for higher electron beam energy with small cone size causing the depth of maximum dose and the rapid dose fall-off region to shift deeper into the phantom. However, the change in the depth-dose curve is small. On the other hand, the rapid dose fall-off region is essentially unaltered when the large cone is used. The penumbra enlarges and electron beam flatness deteriorates with increasing SSD

  14. Generating Converged Accurate Free Energy Surfaces for Chemical Reactions with a Force-Matched Semiempirical Model.

    Science.gov (United States)

    Kroonblawd, Matthew P; Pietrucci, Fabio; Saitta, Antonino Marco; Goldman, Nir

    2018-04-10

    We demonstrate the capability of creating robust density functional tight binding (DFTB) models for chemical reactivity in prebiotic mixtures through force matching to short time scale quantum free energy estimates. Molecular dynamics using density functional theory (DFT) is a highly accurate approach to generate free energy surfaces for chemical reactions, but the extreme computational cost often limits the time scales and range of thermodynamic states that can feasibly be studied. In contrast, DFTB is a semiempirical quantum method that affords up to a thousandfold reduction in cost and can recover DFT-level accuracy. Here, we show that a force-matched DFTB model for aqueous glycine condensation reactions yields free energy surfaces that are consistent with experimental observations of reaction energetics. Convergence analysis reveals that multiple nanoseconds of combined trajectory are needed to reach a steady-fluctuating free energy estimate for glycine condensation. Predictive accuracy of force-matched DFTB is demonstrated by direct comparison to DFT, with the two approaches yielding surfaces with large regions that differ by only a few kcal mol -1 .

  15. Computed Potential Energy Surfaces and Minimum Energy Pathway for Chemical Reactions

    Science.gov (United States)

    Walch, Stephen P.; Langhoff, S. R. (Technical Monitor)

    1994-01-01

    Computed potential energy surfaces are often required for computation of such observables as rate constants as a function of temperature, product branching ratios, and other detailed properties. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method with the Dunning correlation consistent basis sets to obtain accurate energetics, gives useful results for a number of chemically important systems. Applications to complex reactions leading to NO and soot formation in hydrocarbon combustion are discussed.

  16. Determination of the specific surface energy of oxides and glasses in the solid-state

    International Nuclear Information System (INIS)

    Andryushechkin, S.; Karpman, M.

    2000-01-01

    The production and application of coatings on glasses are used widely in technology. The coatings on glass are used for the regulation of optical, decorative, conducting and other technological and physical properties of glass. In particular, it is important to mention the application of glass fibres for the development of composite materials. However, the specific surface energy of glass and, consequently, its adhesion characteristics are relatively low. The values of these characteristics can be changed by the application of different metallic and nonmetallic coatings is characterised by high surface energy. To produce metallic coatings with the required adhesion strength of glass, it is necessary to have information on the specific surface energy of inorganic glass of different chemical composition. The determination of the relationships between the properties and composition of glass is one of the fundamental problems. At present, a large amount of investigations have been carried out into the investigations of the properties of glass in relation to its composition. However, the problem of establishment of relationships between the properties and composition of glass are especially difficult when examining multicomponent systems (technical glass). It is therefore, in to analyse in each case the properties of not the entire system has a whole but the variation of the properties with temperature of the individual components included in the system, the subsequent application of the additivity principle. The large majority of the glasses represent combinations of oxides of the elements of groups I-III and oxides of the transition metals, forming the mixtures, solid solutions of chemical compounds in the glass production process. Thus, analysis of the characteristics of oxides of the alkali, alkali-earth and transition metals makes it possible to obtain initial data for the evaluation of the surface energy, density, molecular mass of glass containing these oxides

  17. On the measurement of the surface energy budget over a land ...

    Indian Academy of Sciences (India)

    The measurement of surface energy balance over a land surface in an open area in Bangalore is reported. Measurements of all variables needed to calculate the surface energy balance on time scales longer than a week are made. Components of radiative fluxes are measured while sensible and latent heat fluxes are ...

  18. Surface energy balance measurements in the Mexico City: a review

    Energy Technology Data Exchange (ETDEWEB)

    Tejeda Martinez, A. [Universidad Veracruzana, Xalapa, Veracruz (Mexico); Jauregui Ostos, E. [Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico, UNAM, Mexico, D.F. (Mexico)

    2005-01-01

    During the last decade of the 20th Century, diverse campaigns for measuring the atmospheric energy balance were performed in downtown Mexico City (School of Mines and Preparatory School No. 7), in the southern suburbs (University Reserve) and in the surrounding rural areas (Plan Texcoco), in addition to a campaign carried out in 1985 in the Tacubaya district, a suburban western peripheral site. The objective was to obtain data for a better understanding of the climatic alterations due to urbanization, particularly to describe the role that the modification of the natural ground cover has played as a result of paving and the construction of urban canyons. In this paper, a review of these campaigns is presented. Energy partitioning in some areas (Tacubaya and Preparatory School No.7) is similar to that observed in urban centers of middle latitudes, whereas the major contrast was observed between Texcoco, with maximum energy consumption through evaporation, and School of Mines, where the latent heat is as low as in a desert. From the values of the correlations among the different components of energy balance, it may be possible to attempt the modeling of the diverse components of energy balance by means of regression equations starting from the net radiation. Those same coefficients distinguish the type of environment: urban, suburban or rural. [Spanish] Las primeras mediciones de balance energetico en la Ciudad de Mexico se realizaron en 1985 en un suburbio al poniente de la ciudad (el observatorio de Tacubaya). Ya en la decada de los anos noventa del siglo XX, dichas observaciones se multiplicaron tanto en el centro historico (antigua Escuela de Minas y en el edificio de la Preparatoria No. 7), como en otros sitios al sur (en terrenos de Ciudad Universitaria) y en la periferia rural (Plan Texcoco). El proposito de estas mediciones ha sido tener un mejor entendimiento de las alteraciones climaticas debidas a la urbanizacion. En este trabajo se presenta una revision

  19. Renewable Energy in the Baltic States. Different Situations

    International Nuclear Information System (INIS)

    Streimikiene, Dalia

    2007-01-01

    In many ways, the Baltic nations seem to be good students with ambitious objectives for applying European directives and the Kyoto Protocol. For example, in 2006, renewable energies already accounted for 9 % in Lithuania, 10 % in Estonia and 43 % in Latvia (5.2 % in the EU-15) of primary energy output. This should increase to 12 %, 15 % and 50 % in 2010 (12 % in the EU-15) respectively. While all are dependent on oil imports, their own resources vary: nuclear power in Lithuania (at least until 2009 when the last reactor of the Ignalina power station will close, with EU compensation), oil shale feeds Estonian power stations, wood in Latvia. The latter must import electricity while the two other countries produce double their domestic demand. All three are linked to the Russian power grid built up during the Soviet era rather than the European. Nevertheless, the share of renewable energy produced electricity is very small in these two producer countries, unlike Latvia which has hydraulic resources. The three countries have very different taxation on energy and electrical products, including renewable energy price support. All were granted transitional periods of differing lengths to apply European standard. The Baltic nations produce low greenhouse gas emissions and only Estonia has organized an emission rights trading market

  20. Experimental and numerical analyses of different extended surfaces

    International Nuclear Information System (INIS)

    Diani, A; Mancin, S; Zilio, C; Rossetto, L

    2012-01-01

    Air is a cheap and safe fluid, widely used in electronic, aerospace and air conditioning applications. Because of its poor heat transfer properties, it always flows through extended surfaces, such as finned surfaces, to enhance the convective heat transfer. In this paper, experimental results are reviewed and numerical studies during air forced convection through extended surfaces are presented. The thermal and hydraulic behaviours of a reference trapezoidal finned surface, experimentally evaluated by present authors in an open-circuit wind tunnel, has been compared with numerical simulations carried out by using the commercial CFD software COMSOL Multiphysics. Once the model has been validated, numerical simulations have been extended to other rectangular finned configurations, in order to study the effects of the fin thickness, fin pitch and fin height on the thermo-hydraulic behaviour of the extended surfaces. Moreover, several pin fin surfaces have been simulated in the same range of operating conditions previously analyzed. Numerical results about heat transfer and pressure drop, for both plain finned and pin fin surfaces, have been compared with empirical correlations from the open literature, and more accurate equations have been developed, proposed, and validated.

  1. The difference between energy consumption and energy cost: Modelling energy tariff structures for water resource recovery facilities.

    Science.gov (United States)

    Aymerich, I; Rieger, L; Sobhani, R; Rosso, D; Corominas, Ll

    2015-09-15

    The objective of this paper is to demonstrate the importance of incorporating more realistic energy cost models (based on current energy tariff structures) into existing water resource recovery facilities (WRRFs) process models when evaluating technologies and cost-saving control strategies. In this paper, we first introduce a systematic framework to model energy usage at WRRFs and a generalized structure to describe energy tariffs including the most common billing terms. Secondly, this paper introduces a detailed energy cost model based on a Spanish energy tariff structure coupled with a WRRF process model to evaluate several control strategies and provide insights into the selection of the contracted power structure. The results for a 1-year evaluation on a 115,000 population-equivalent WRRF showed monthly cost differences ranging from 7 to 30% when comparing the detailed energy cost model to an average energy price. The evaluation of different aeration control strategies also showed that using average energy prices and neglecting energy tariff structures may lead to biased conclusions when selecting operating strategies or comparing technologies or equipment. The proposed framework demonstrated that for cost minimization, control strategies should be paired with a specific optimal contracted power. Hence, the design of operational and control strategies must take into account the local energy tariff. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Tensile bond strength of metal bracket bonding to glazed ceramic surfaces with different surface conditionings.

    Science.gov (United States)

    Akhoundi, Ms Ahmad; Kamel, M Rahmati; Hashemi, Sh Mahmood; Imani, M

    2011-01-01

    The objective of this study was to compare the tensile bond strength of metal brackets bonding to glazed ceramic surfaces using three various surface treatments. Forty two glazed ceramic disks were assigned to three groups. In the first and second groups the specimens were etched with 9.5% hydrofluoric acid (HFA). Subsequently in first group, ceramic primer and adhesive were applied, but in second group a bonding agent alone was used. In third group, specimens were treated with 35% phosphoric acid followed by ceramic primer and adhesive application. Brackets were bonded with light cure composites. The specimens were stored in distilled water in the room temperature for 24 hours and thermocycled 500 times between 5°C and 55°C. The universal testing machine was used to test the tensile bond strength and the adhesive remenant index scores between three groups was evaluated. The data were subjected to one-way ANOVA, Tukey and Kruskal-Wallis tests respectively. The tensile bond strength was 3.69±0.52 MPa forfirst group, 2.69±0.91 MPa for second group and 3.60±0.41 MPa for third group. Group II specimens showed tensile strength values significantly different from other groups (Ptensile bond strength.

  3. Hysteresis of boiling for different tunnel-pore surfaces

    Directory of Open Access Journals (Sweden)

    Pastuszko Robert

    2015-01-01

    Full Text Available Analysis of boiling hysteresis on structured surfaces covered with perforated foil is proposed. Hysteresis is an adverse phenomenon, preventing high heat flux systems from thermal stabilization, characterized by a boiling curve variation at an increase and decrease of heat flux density. Experimental data were discussed for three kinds of enhanced surfaces: tunnel structures (TS, narrow tunnel structures (NTS and mini-fins covered with the copper wire net (NTS-L. The experiments were carried out with water, R-123 and FC-72 at atmospheric pressure. A detailed analysis of the measurement results identified several cases of type I, II and III for TS, NTS and NTS-L surfaces.

  4. Quantifying Surface Energy Flux Estimation Uncertainty Using Land Surface Temperature Observations

    Science.gov (United States)

    French, A. N.; Hunsaker, D.; Thorp, K.; Bronson, K. F.

    2015-12-01

    Remote sensing with thermal infrared is widely recognized as good way to estimate surface heat fluxes, map crop water use, and detect water-stressed vegetation. When combined with net radiation and soil heat flux data, observations of sensible heat fluxes derived from surface temperatures (LST) are indicative of instantaneous evapotranspiration (ET). There are, however, substantial reasons LST data may not provide the best way to estimate of ET. For example, it is well known that observations and models of LST, air temperature, or estimates of transport resistances may be so inaccurate that physically based model nevertheless yield non-meaningful results. Furthermore, using visible and near infrared remote sensing observations collected at the same time as LST often yield physically plausible results because they are constrained by less dynamic surface conditions such as green fractional cover. Although sensitivity studies exist that help identify likely sources of error and uncertainty, ET studies typically do not provide a way to assess the relative importance of modeling ET with and without LST inputs. To better quantify model benefits and degradations due to LST observational inaccuracies, a Bayesian uncertainty study was undertaken using data collected in remote sensing experiments at Maricopa, Arizona. Visible, near infrared and thermal infrared data were obtained from an airborne platform. The prior probability distribution of ET estimates were modeled using fractional cover, local weather data and a Penman-Monteith mode, while the likelihood of LST data was modeled from a two-source energy balance model. Thus the posterior probabilities of ET represented the value added by using LST data. Results from an ET study over cotton grown in 2014 and 2015 showed significantly reduced ET confidence intervals when LST data were incorporated.

  5. Physicochemical state of the nanotopographic surface of commercially pure titanium following anodization-hydrothermal treatment reveals significantly improved hydrophilicity and surface energy profiles.

    Science.gov (United States)

    Takebe, Jun; Ito, Shigeki; Miura, Shingo; Miyata, Kyohei; Ishibashi, Kanji

    2012-01-01

    A method of coating commercially pure titanium (cpTi) implants with a highly crystalline, thin hydroxyapatite (HA) layer using discharge anodic oxidation followed by hydrothermal treatment (Spark discharged Anodic oxidation treatment ; SA-treated cpTi) has been reported for use in clinical dentistry. We hypothesized that a thin HA layer with high crystallinity and nanostructured anodic titanium oxide film on such SA-treated cpTi implant surfaces might be a crucial function of their surface-specific potential energy. To test this, we analyzed anodic oxide (AO) cpTi and SA-treated cpTi disks by SEM and AFM. Contact angles and surface free energy of each disk surface was measured using FAMAS software. High-magnification SEM and AFM revealed the nanotopographic structure of the anodic titanium oxide film on SA-treated cpTi; however, this was not observed on the AO cpTi surface. The contact angle and surface free energy measurements were also significantly different between AO cpTi and SA-treated cpTi surfaces (Tukey's, P<0.05). These data indicated that the change of physicochemical properties of an anodic titanium oxide film with HA crystals on an SA-treated cpTi surface may play a key role in the phenomenon of osteoconduction during the process of osseointegration. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Optimal portfolio selection between different kinds of Renewable energy sources

    Energy Technology Data Exchange (ETDEWEB)

    Zakerinia, MohammadSaleh; Piltan, Mehdi; Ghaderi, Farid

    2010-09-15

    In this paper, selection of the optimal energy supply system in an industrial unit is taken into consideration. This study takes environmental, economical and social parameters into consideration in modeling along with technical factors. Several alternatives which include renewable energy sources, micro-CHP systems and conventional system has been compared by means of an integrated model of linear programming and three multi-criteria approaches (AHP, TOPSIS and ELECTRE III). New parameters like availability of sources, fuels' price volatility, besides traditional factors are considered in different scenarios. Results show with environmental preferences, renewable sources and micro-CHP are good alternatives for conventional systems.

  7. Applications of SOECs in different types of energy systems

    DEFF Research Database (Denmark)

    Mathiesen, Brian Vad; Ridjan, Iva; Hansen, Kenneth

    Different aspects of electrolyser integration in energy systems was investigated in order to determine the potential of using this technology in the future. The first analysis examined the influence of the use of co-electrolysis for the fuel production process in comparison with using steam....... The analysis shows that different system designs influence the feasible utilisation capacity of electrolysers differently and this is mainly connected with the system flexibility....... for using combined capacities of SOEC and SOFC was investigated as this can potentially improve the profitability of the investment, but also improve the stability of the energy system by offering grid-balancing capacity when intermittent resources cannot meet the demand for electricity. Finally, five...

  8. Characterization of neutrophil adhesion to different titanium surfaces

    Indian Academy of Sciences (India)

    Scanning electron microscopy and flow cytometry were used to measure .... discs containing neutrophils were inverted and placed in a tube assembly that ... Representative AFM images of smooth (a) and rough (b) Ti surfaces. The arithmetic ...

  9. Critical insight into the influence of the potential energy surface on fission dynamics

    International Nuclear Information System (INIS)

    Mazurek, K.; Schmitt, C.; Wieleczko, J. P.; Ademard, G.; Nadtochy, P. N.

    2011-01-01

    The present work is dedicated to a careful investigation of the influence of the potential energy surface on the fission process. The time evolution of nuclei at high excitation energy and angular momentum is studied by means of three-dimensional Langevin calculations performed for two different parametrizations of the macroscopic potential: the Finite Range Liquid Drop Model (FRLDM) and the Lublin-Strasbourg Drop (LSD) prescription. Depending on the mass of the system, the topology of the potential throughout the deformation space of interest in fission is observed to noticeably differ within these two approaches, due to the treatment of curvature effects. When utilized in the dynamical calculation as the driving potential, the FRLDM and LSD models yield similar results in the heavy-mass region, whereas the predictions can be strongly dependent on the Potential Energy Surface (PES) for medium-mass nuclei. In particular, the mass, charge, and total kinetic energy distributions of the fission fragments are found to be narrower with the LSD prescription. The influence of critical model parameters on our findings is carefully investigated. The present study sheds light on the experimental conditions and signatures well suited for constraining the parametrization of the macroscopic potential. Its implication regarding the interpretation of available experimental data is briefly discussed.

  10. Theory of Covalent Adsorbate Frontier Orbital Energies on Functionalized Light-Absorbing Semiconductor Surfaces.

    Science.gov (United States)

    Yu, Min; Doak, Peter; Tamblyn, Isaac; Neaton, Jeffrey B

    2013-05-16

    Functional hybrid interfaces between organic molecules and semiconductors are central to many emerging information and solar energy conversion technologies. Here we demonstrate a general, empirical parameter-free approach for computing and understanding frontier orbital energies - or redox levels - of a broad class of covalently bonded organic-semiconductor surfaces. We develop this framework in the context of specific density functional theory (DFT) and many-body perturbation theory calculations, within the GW approximation, of an exemplar interface, thiophene-functionalized silicon (111). Through detailed calculations taking into account structural and binding energetics of mixed-monolayers consisting of both covalently attached thiophene and hydrogen, chlorine, methyl, and other passivating groups, we quantify the impact of coverage, nonlocal polarization, and interface dipole effects on the alignment of the thiophene frontier orbital energies with the silicon band edges. For thiophene adsorbate frontier orbital energies, we observe significant corrections to standard DFT (∼1 eV), including large nonlocal electrostatic polarization effects (∼1.6 eV). Importantly, both results can be rationalized from knowledge of the electronic structure of the isolated thiophene molecule and silicon substrate systems. Silicon band edge energies are predicted to vary by more than 2.5 eV, while molecular orbital energies stay similar, with the different functional groups studied, suggesting the prospect of tuning energy alignment over a wide range for photoelectrochemistry and other applications.

  11. Energy behavior of solar hot water systems under different conditions

    International Nuclear Information System (INIS)

    Fuentes Lombá, Osmanys; Torres Ten, Alonso; Arzuaga Machado, Yusnel; Hernández, Massipe J. Raúl; Cueva Gonzales, Wagner

    2017-01-01

    By means of numerical simulations in TRNSYS v14 the influence of the solar absorption area of a system for heating water with solar energy, composed by a flat solar collector and a tank thermo-accumulator, on its energy efficiency. For the study, the solar collectors EDWARDS, ISOFOTÓN 1, ISOFOTÓN 2, MADE, ROLDAN and IBERSOLAR of absorption area 2, 1,9, 1,88, 2, 1,9 and 2,3 m2 respectively were chosen. For each collector, the energy performance was simulated for one year, setting 200 L for the accumulation volume and 50 °C for the intake temperature. Despite the different characteristics of each collector, their behavior is quite similar showing a very mature technology. (author)

  12. Observation of core-level binding energy shifts between (100) surface and bulk atoms of epitaxial CuInSe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, A.J. [Colorado School of Mines, Golden, CO (United States); Berry, G.; Rockett, A. [Univ. of Illinois, Urbana-Champaign, IL (United States)] [and others

    1997-04-01

    Core-level and valence band photoemission from semiconductors has been shown to exhibit binding energy differences between surface atoms and bulk atoms, thus allowing one to unambiguously distinguish between the two atomic positions. Quite clearly, surface atoms experience a potential different from the bulk due to the lower coordination number - a characteristic feature of any surface is the incomplete atomic coordination. Theoretical accounts of this phenomena are well documented in the literature for III-V and II-VI semiconductors. However, surface state energies corresponding to the equilibrium geometry of (100) and (111) surfaces of Cu-based ternary chalcopyrite semiconductors have not been calculated or experimental determined. These compounds are generating great interest for optoelectronic and photovoltaic applications, and are an isoelectronic analog of the II-VI binary compound semiconductors. Surface core-level binding energy shifts depend on the surface cohesive energies, and surface cohesive energies are related to surface structure. For ternary compound semiconductor surfaces, such as CuInSe{sub 2}, one has the possibility of variations in surface stoichiometry. Applying standard thermodynamical calculations which consider the number of individual surface atoms and their respective chemical potentials should allow one to qualitatively determine the magnitude of surface core-level shifts and, consequently, surface state energies.

  13. Observation of core-level binding energy shifts between (100) surface and bulk atoms of epitaxial CuInSe2

    International Nuclear Information System (INIS)

    Nelson, A.J.; Berry, G.; Rockett, A.

    1997-01-01

    Core-level and valence band photoemission from semiconductors has been shown to exhibit binding energy differences between surface atoms and bulk atoms, thus allowing one to unambiguously distinguish between the two atomic positions. Quite clearly, surface atoms experience a potential different from the bulk due to the lower coordination number - a characteristic feature of any surface is the incomplete atomic coordination. Theoretical accounts of this phenomena are well documented in the literature for III-V and II-VI semiconductors. However, surface state energies corresponding to the equilibrium geometry of (100) and (111) surfaces of Cu-based ternary chalcopyrite semiconductors have not been calculated or experimental determined. These compounds are generating great interest for optoelectronic and photovoltaic applications, and are an isoelectronic analog of the II-VI binary compound semiconductors. Surface core-level binding energy shifts depend on the surface cohesive energies, and surface cohesive energies are related to surface structure. For ternary compound semiconductor surfaces, such as CuInSe 2 , one has the possibility of variations in surface stoichiometry. Applying standard thermodynamical calculations which consider the number of individual surface atoms and their respective chemical potentials should allow one to qualitatively determine the magnitude of surface core-level shifts and, consequently, surface state energies

  14. Role of surface energy and nano-roughness in the removal efficiency of bacterial contamination by nonwoven wipes from frequently touched surfaces

    Science.gov (United States)

    Edwards, Nicholas W. M.; Best, Emma L.; Connell, Simon D.; Goswami, Parikshit; Carr, Chris M.; Wilcox, Mark H.; Russell, Stephen J.

    2017-12-01

    Healthcare associated infections (HCAIs) are responsible for substantial patient morbidity, mortality and economic cost. Infection control strategies for reducing rates of transmission include the use of nonwoven wipes to remove pathogenic bacteria from frequently touched surfaces. Wiping is a dynamic process that involves physicochemical mechanisms to detach and transfer bacteria to fibre surfaces within the wipe. The purpose of this study was to determine the extent to which systematic changes in fibre surface energy and nano-roughness influence removal of bacteria from an abiotic polymer surface in dry wiping conditions, without liquid detergents or disinfectants. Nonwoven wipe substrates composed of two commonly used fibre types, lyocell (cellulosic) and polypropylene, with different surface energies and nano-roughnesses, were manufactured using pilot-scale nonwoven facilities to produce samples of comparable structure and dimensional properties. The surface energy and nano-roughness of some lyocell substrates were further adjusted by either oxygen (O2) or hexafluoroethane (C2F6) gas plasma treatment. Static adpression wiping of an inoculated surface under dry conditions produced removal efficiencies of between 9.4% and 15.7%, with no significant difference (p < 0.05) in the relative removal efficiencies of Escherichia coli, Staphylococcus aureus or Enterococcus faecalis. However, dynamic wiping markedly increased peak wiping efficiencies to over 50%, with a minimum increase in removal efficiency of 12.5% and a maximum increase in removal efficiency of 37.9% (all significant at p < 0.05) compared with static wiping, depending on fibre type and bacterium. In dry, dynamic wiping conditions, nonwoven wipe substrates with a surface energy closest to that of the contaminated surface produced the highest E. coli removal efficiency, while the associated increase in fibre nano-roughness abrogated this trend with S. aureus and E. faecalis.

  15. An energy-based equilibrium contact angle boundary condition on jagged surfaces for phase-field methods.

    Science.gov (United States)

    Frank, Florian; Liu, Chen; Scanziani, Alessio; Alpak, Faruk O; Riviere, Beatrice

    2018-08-01

    We consider an energy-based boundary condition to impose an equilibrium wetting angle for the Cahn-Hilliard-Navier-Stokes phase-field model on voxel-set-type computational domains. These domains typically stem from μCT (micro computed tomography) imaging of porous rock and approximate a (on μm scale) smooth domain with a certain resolution. Planar surfaces that are perpendicular to the main axes are naturally approximated by a layer of voxels. However, planar surfaces in any other directions and curved surfaces yield a jagged/topologically rough surface approximation by voxels. For the standard Cahn-Hilliard formulation, where the contact angle between the diffuse interface and the domain boundary (fluid-solid interface/wall) is 90°, jagged surfaces have no impact on the contact angle. However, a prescribed contact angle smaller or larger than 90° on jagged voxel surfaces is amplified. As a remedy, we propose the introduction of surface energy correction factors for each fluid-solid voxel face that counterbalance the difference of the voxel-set surface area with the underlying smooth one. The discretization of the model equations is performed with the discontinuous Galerkin method. However, the presented semi-analytical approach of correcting the surface energy is equally applicable to other direct numerical methods such as finite elements, finite volumes, or finite differences, since the correction factors appear in the strong formulation of the model. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. Determining photon energy absorption parameters for different soil samples

    International Nuclear Information System (INIS)

    Kucuk, Nil; Cakir, Merve; Tumsavas, Zeynal

    2013-01-01

    The mass attenuation coefficients (μ s ) for five different soil samples were measured at 661.6, 1173.2 and 1332.5 keV photon energies. The soil samples were separately irradiated with 137 Cs and 60 Co (370 kBq) radioactive point gamma sources. The measurements were made by performing transmission experiments with a 2″ x 2″ NaI(Tl) scintillation detector, which had an energy resolution of 7% at 0.662 MeV for the gamma-rays from the decay of 137 Cs. The effective atomic numbers (Z eff ) and the effective electron densities (N eff ) were determined experimentally and theoretically using the obtained μ s values for the soil samples. Furthermore, the Z eff and N eff values of the soil samples were computed for the total photon interaction cross-sections using theoretical data over a wide energy region ranging from 1 keV to 15 MeV. The experimental values of the soils were found to be in good agreement with the theoretical values. Sandy loam and sandy clay loam soils demonstrated poor photon energy absorption characteristics. However, clay loam and clay soils had good photon energy absorption characteristics. (author)

  17. In vitro effect of energy drinks on human enamel surface

    Directory of Open Access Journals (Sweden)

    Marise Sano Suga MATUMOTO

    Full Text Available Abstract Introduction Energy drinks (ED possess low pH and citric acid in their composition, making them potentially erosive beverages that can contribute to the high dental erosion rates found currently in the general population and also in young people. Objective To evaluate the mean pH and titratable acidity of commercial ED and the influence of a brand of ED on the superficial microhardness of human enamel. Material and method Ten commercial ED were selected and the pH of two lots of each ED with and without gas was obtained. Acid titration was conducted with the addition of NaOH aliquots until the pH 7 was reached. Eighteen human enamel specimens were allocated in three groups (N=6, Red Bull (RB, Red Bull Light (RBL and distilled water (C, submitted to an acid challenge with the ED, six consecutive times, with 12 hours intervals, during three days. Knoop microhardness was measured before and after the acid challenge. Result All ED brands tested presented low pH levels ranging from 2.1 to 3.2. Regarding titratable acidity, it was found that the amount of base required promoting the neutralization of the solutions ranged from 1200μL to 3750μL. Samples of human enamel in the RB and RBL groups submitted to the acid challenge presented significantly decreased Knoop microhardness when compared with the group C. Conclusion All ED examined have potential to promote mineral loss due to the low pH and high titratable acidity. The ED analyzed promoted significant mineral losses on the dental enamel surface.

  18. Using radiometric surface temperature for surface energy flux estimation in Mediterranean drylands from a two-source perspective

    DEFF Research Database (Denmark)

    Morillas, L.; Garcia Garcia, Monica; Nieto Solana, Hector

    2013-01-01

    A two-source model (TSM) for surface energy balance, considering explicitly soil and vegetation components, was tested under water stress conditions. The TSM evaluated estimates the sensible heat flux (H) using the surface-air thermal gradient and the latent heat flux (LE) as a residual from the ...

  19. Sex differences of human cortical blood flow and energy metabolism

    DEFF Research Database (Denmark)

    Aanerud, Joel; Borghammer, Per; Rodell, Anders

    2017-01-01

    cerebral blood flow and cerebral metabolic rate of oxygen as functions of age in healthy volunteers of both sexes. Cerebral metabolic rate of oxygen did not change with age for either sex and there were no differences of mean values of cerebral metabolic rate of oxygen between men and women in cerebral...... cortex. Women had significant decreases of cerebral blood flow as function of age in frontal and parietal lobes. Young women had significantly higher cerebral blood flow than men in frontal and temporal lobes, but these differences had disappeared at age 65. The absent sex difference of cerebral energy...... turnover suggests that the known differences of synaptic density between the sexes are counteracted by opposite differences of individual synaptic activity....

  20. An Integrated Surface Engineering Technology Development for Improving Energy Efficiency of Engine Components

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Hsu; Liming Chang; Huan Zhan

    2009-05-31

    Frictional losses are inherent in most practical mechanical systems. The ability to control friction offers many opportunities to achieve energy conservation. Over the years, materials, lubricants, and surface modifications have been used to reduce friction in automotive and diesel engines. However, in recent years, progress in friction reduction technology has slowed because many of the inefficiencies have been eliminated. A new avenue for friction reduction is needed. Designing surfaces specifically for friction reduction with concomitant enhanced durability for various engine components has emerged recently as a viable opportunity due to advances in fabrication and surface finishing techniques. Recently, laser ablated dimples on surfaces have shown friction reduction properties and have been demonstrated successfully in conformal contacts such as seals where the speed is high and the load is low. The friction reduction mechanism in this regime appears to depend on the size, patterns, and density of dimples in the contact. This report describes modeling efforts in characterizing surface textures and understanding their mechanisms for enhanced lubrication under high contact pressure conditions. A literature survey is first presented on the development of descriptors for irregular surface features. This is followed by a study of the hydrodynamic effects of individual micro-wedge dimples using the analytical solution of the 1-D Reynolds equation and the determination of individual components of the total friction resistance. The results obtained provide a better understanding of the dimple orientation effects and the approach which may be used to further compare the friction reduction provided by different texture patterns.

  1. Surface modifications of AISI 420 stainless steel by low energy Yttrium ions

    Science.gov (United States)

    Nassisi, Vincenzo; Delle Side, Domenico; Turco, Vito; Martina, Luigi

    2018-01-01

    In this work, we study surface modifications of AISI 420 stainless steel specimens in order to improve their surface properties. Oxidation resistance and surface micro-hardness were analyzed. Using an ion beam delivered by a Laser Ion Source (LIS) coupled to an electrostatic accelerator, we performed implantation of low energy yttrium ions on the samples. The ions experienced an acceleration passing through a gap whose ends had a potential difference of 60 kV. The gap was placed immediately before the samples surface. The LIS produced high ions fluxes per laser pulse, up to 3x1011 ions/cm2, resulting in a total implanted flux of 7x1015 ions/cm2. The samples were characterized before and after ion implantation using two analytical techniques. They were also thermally treated to investigate the oxide scale. The crystal phases were identified by an X-ray diffractometer, while the micro-hardness was assayed using the scratch test and a profilometer. The first analysis was applied to blank, implanted and thermally treated sample surface, while the latter was applied only to blank and implanted sample surfaces. We found a slight increase in the hardness values and an increase to oxygen resistance. The implantation technique we used has the advantages, with respect to conventional methods, to modify the samples at low temperature avoiding stray diffusion of ions inside the substrate bulk.

  2. Surface modifications of AISI 420 stainless steel by low energy Yttrium ions

    Directory of Open Access Journals (Sweden)

    Nassisi Vincenzo

    2018-01-01

    Full Text Available In this work, we study surface modifications of AISI 420 stainless steel specimens in order to improve their surface properties. Oxidation resistance and surface micro-hardness were analyzed. Using an ion beam delivered by a Laser Ion Source (LIS coupled to an electrostatic accelerator, we performed implantation of low energy yttrium ions on the samples. The ions experienced an acceleration passing through a gap whose ends had a potential difference of 60 kV. The gap was placed immediately before the samples surface. The LIS produced high ions fluxes per laser pulse, up to 3x1011 ions/cm2, resulting in a total implanted flux of 7x1015 ions/cm2. The samples were characterized before and after ion implantation using two analytical techniques. They were also thermally treated to investigate the oxide scale. The crystal phases were identified by an X-ray diffractometer, while the micro-hardness was assayed using the scratch test and a profilometer. The first analysis was applied to blank, implanted and thermally treated sample surface, while the latter was applied only to blank and implanted sample surfaces. We found a slight increase in the hardness values and an increase to oxygen resistance. The implantation technique we used has the advantages, with respect to conventional methods, to modify the samples at low temperature avoiding stray diffusion of ions inside the substrate bulk.

  3. Structure and morphology of surface of silicon crystals to be applied for channeling at relativistic energies

    International Nuclear Information System (INIS)

    Vomiero, Alberto; Restello, Silvio; Scian, Carlo; Marchi, Enrico Boscolo; Mea, Gianantonio Della; Guidi, Vincenzo; Milan, Emiliano; Baricordi, Stefano; Martinelli, Giuliano; Carnera, Alberto; Sambo, Andrea

    2006-01-01

    Bent crystals can be successfully applied for extraction/collimation of relativistic particles. A crucial feature to obtain high extraction efficiencies is the treatment of the surfaces being encountered by the beam, since mechanical operations induce considerable lattice imperfections. In order to remove the superficial damaged layer a planar etching can be applied on the surface exposed to the beam. This work presents a systematic study of the morphology and the crystalline perfection of the surface of the samples that have been used in accelerators with high efficiency. Crystals with different surface treatments have been investigated. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were applied on the characterisation of surface morphology. Low energy backscattering channeling of 2-MeV α particles or protons was used as a probe for the crystalline structure. The presence of a superficial damaged layer in the samples just after mechanical treatment was unveiled, while, in contrast, chemical etching leaves a surface with high crystalline perfection that can be related to the record efficiency

  4. Discrimination between different kind of surface defects on Compac Discs

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Wickerhauser, M.V.

    2004-01-01

    Compact Disc players have problems playing discs with surface defects such as scratches and finger prints. The problem is that handling normal disturbances such as mechanical shocks etc, require a high bandwidth of the controllers which keep the Optical Pick-Up focused and radial tracked on the i......Compact Disc players have problems playing discs with surface defects such as scratches and finger prints. The problem is that handling normal disturbances such as mechanical shocks etc, require a high bandwidth of the controllers which keep the Optical Pick-Up focused and radial tracked...... on the information track on the disc. In order for the controllers to handle the surface defects it is required that they are non-sensitive to the frequency contents of the defect, since a defect can be viewed as a disturbance on the measurements. A simple solution to this problem is to decrease the controller...

  5. Discrimation among different kind of surface defects on Compact Discs

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Wickerhauser, M.V.

    2003-01-01

    Compact Disc players have problems playing discs with surface defects such as scratches and finger prints. The problem is that handling normal disturbances such as mechanical shocks etc, require a high bandwidth of the controllers which keep the Optical Pick-Up focused and radial tracked on the i......Compact Disc players have problems playing discs with surface defects such as scratches and finger prints. The problem is that handling normal disturbances such as mechanical shocks etc, require a high bandwidth of the controllers which keep the Optical Pick-Up focused and radial tracked...... on the information track on the disc. In order for the controllers to handle the surface defects it is required that they are non-sensitive to the frequency contents of the defect, since a defect can be viewed as a disturbance on the measurements. A simple solution to this problem is to decrease the controller...

  6. Tribological behaviors of UHMWPE composites with different counter surface morphologies

    Science.gov (United States)

    Wang, Yanzhen; Yin, Zhongwei; Li, Hulin; Gao, Gengyuan

    2017-12-01

    The influence of counter surface morphologies on hybrid glass fiber (GF) and carbon fiber (CF) filled ultrahigh molecular weight polyethylene (UHMWPE) were studied under various contact pressure and sliding speed against GCr15 steel in dry condition. The goals were to investigate the tribological behavior of GF/CF/UHMWPE composite as a kind of water lubricated journal bearing material. The friction and wear behavior of composites were examined using a pin-on-disc tribometer. The morphologies of the worn surface were examined by scanning electron microscopy (SEM) and laser 3D micro-imaging and profile measurement. Generally, the wear rate and friction coefficient of composites increase as the increment of counter surface roughness. The friction coefficient increases firstly and then decrease with an increase in sliding speed and contact pressure for counterface with Ra=0.2 and 3.5 μm, while the friction coefficient decreased for counterface with Ra=0.6 μm.

  7. Differences in energy capacities between tennis players and runners.

    Science.gov (United States)

    Novak, Dario; Vucetić, Vlatko; Zugaj, Sanja

    2013-05-01

    The primary purpose of this study was to determine differences between elite athletes and tennis players in order to provide a clearer picture regarding the energy demands in modern tennis. Forty-eight (48) athletes and 24 tennis players from Croatian national leagues were compared in morphological and physiological parameters of an all-out incremental treadmill test with gas exchange measurements. Tennis players' HRmax (192.96+/-7.75 bpm) shows values that are most different to 400-meters sprinters (200.13+/-6.95 bpm). Maximum running speed of tennis players on the treadmill (vmax) is no different with the speed achieved by sprinters, while there are significant differences among other athletes. Values in running speed at anaerobic threshold (vAnT) show no statistically significant difference with the values for athlete sprinters and 400-m sprinters. Values of RvO2max for tennis players indicate significant similarities with athlete sprinters and 400-m sprinters while the values of RvO2AnT are nearly identical with the values for sprinters and show no statistically significant differences (psprint endurance in tennis players. Knowing these characteristics is the basis for planning and implementing training systems that will enable the increase and optimal usage of energy capacities of tennis players in possibly improving sports results.

  8. Structural dependence of the 5d-metal surface energies as deduced from surface core-level shift measurements

    International Nuclear Information System (INIS)

    Mrartensson, N.; Saalfeld, H.B.; Kuhlenbeck, H.; Neumann, M.

    1989-01-01

    Surface core-level shift measurements performed at the BESSY storage ring yield -0.41(2) eV for Os(0001) and 0.00(10) eV for Re(0001). An analysis of the surface shifts in the 5d transition series shows that the surface energy as a function of Z has a maximum at lower Z for the bcc phase than for the fcc-hcp phases, at W and between Re and Os, respectively

  9. Tensile Bond Strength of Metal Bracket Bonding to Glazed Ceramic Surfaces With Different Surface Conditionings

    Directory of Open Access Journals (Sweden)

    M. Imani

    2011-12-01

    Full Text Available Objective: The objective of this study was to compare the tensile bond strength of metal brackets bonding to glazed ceramic surfaces using three various surface treatments.Materials and Methods: Forty two glazed ceramic disks were assigned to three groups. In the first and second groups the specimens were etched with 9.5% hydrofluoric acid (HFA. Subsequently in first group, ceramic primer and adhesive were applied, but in second group a bonding agent alone was used. In third group, specimens were treated with 35% phosphoric acid followed by ceramic primerand adhesive application. Brackets were bonded with light cure composites. The specimens were stored in distilled water in the room temperature for 24 hours and thermocycled 500 times between 5°C and 55°C. The universal testing machine was used to test the tensile bond strength and the adhesive remenant index scores between three groups was evaluated. The data were subjected to one-way ANOVA, Tukey and Kruskal-Wallis tests respectively.Results: The tensile bond strength was 3.69±0.52 MPa forfirst group, 2.69±0.91 MPa for second group and 3.60±0.41 MPa for third group. Group II specimens showed tensile strength values significantly different from other groups (P<0.01.Conclusion: In spite of limitations in laboratory studies it may be concluded that in application of Scotch bond multipurpose plus adhesive, phosphoric acid can be used instead of HFA for bonding brackets to the glazed ceramic restorations with enough tensile bond strength.

  10. Energy and environmental consciousness. Differences between advanced and developing countries

    International Nuclear Information System (INIS)

    Takeshita, Takashi

    1999-01-01

    The purpose of the present study is to understand how much differences there are between advanced countries and developing countries in terms of environmental and energy consciousness. We are experiencing now a big dilemma of the human desire to continue to exist and, at the same time, to develop the economy against the worsening of the Earth's environmental conditions. Understanding international differences of environmental and energy consciousness is a short way to solve this dilemma. The results of the present study were that peoples from advanced countries feel that science and technology are sometimes unreliable, while those from developing countries, are willing to rely upon them. However regardless of the country, people share the same consciousness about Earth's environment. In both, advanced and developing countries, people are reluctant to give up living comforts, unless this leads to a higher standard of living. Based on this result, the author would like to conduct another survey concerning the consciousness of future lifestyle. (author)

  11. Electrode surface engineering by atomic layer deposition: A promising pathway toward better energy storage

    KAUST Repository

    Ahmed, Bilal; Xia, Chuan; Alshareef, Husam N.

    2016-01-01

    high capacities and energy and power densities. These developments can extend battery life in portable devices, and open new markets such as electric vehicles and large-scale grid energy storage. It is well known that surface reactions largely determine

  12. Environmental evaluation of different forms of electric energy generation

    International Nuclear Information System (INIS)

    Guena, Ana Maria de Oliveira

    2007-01-01

    Electric energy has an important function in the modem world; it is fundamental for progress and development. The electricity discovery allowed improvements in several areas: health, water and food supply, quality of life and sanitary conditions, and contributed also to the establishment of the capitalist and consumption society. The use of oil as an energy generation source was the impulse for the industrial revolution and machines, motors and generators were developed contributing to the progress This also brought the pollutant gases emission (CO 2 , CO, SO x and NO x ) and other substances that had contributed to the greenhouse effect, the ozone hole and the acid rain, modifying the balance of the planet. The development and implementation of other forms of energy generation caused local changes, where they were installed, giving rise to environmental impacts. This work presents an evaluation about different forms of electrical energy generation and the environmental impacts relative to each one of them. Five forms of electric energy generation were considered: thermoelectric, nuclear, hydroelectric, wind and solar energy. The implementation and the development of the petroleum industry in the world and in Brazil are presented. The geology of the oil, its extraction and quality improvement, besides details of the functioning of three types of thermoelectric power plants - coal, gas and oil - are also discussed. The specific as well as the environmental impacts they have in common are highlighted. The impacts originated from the deactivation of each one of them are also pointed out. The discovery and the development of nuclear energy in Brazil and in the world as well as the functioning of a nuclear power plant, the impacts generated by its operation and decommissioning are presented. The history, functioning and development of hydroelectric energy generation in Brazil, characterized by the great plants, are related to environmental aspects The environmental

  13. Sebum/Meibum Surface Film Interactions and Phase Transitional Differences.

    Science.gov (United States)

    Mudgil, Poonam; Borchman, Douglas; Gerlach, Dylan; Yappert, Marta C

    2016-05-01

    Sebum may contribute to the composition of the tear film lipid layer naturally or as a contaminant artifact from collection. The aims of this study were to determine: if sebum changes the rheology of meibum surface films; if the resonance near 5.2 ppm in the 1H-NMR spectra of sebum is due to squalene (SQ); and if sebum or SQ, a major component of sebum, interacts with human meibum. Human meibum was collected from the lid margin with a platinum spatula. Human sebum was collected using lipid absorbent tape. Langmuir trough technology was used to measure the rheology of surface films. Infrared spectroscopy was used to measure lipid conformation and phase transitions. We used 1H-NMR to measure composition and confirm the primary structure of SQ. The NMR resonance near 5.2 ppm in the spectra of human sebum was from SQ which composed 28 mole percent of sebum. Both sebum and SQ lowered the lipid order of meibum. Sebum expanded meibum films at lower concentrations and condensed meibum films at higher concentrations. Sebum caused meibum to be more stable at higher pressures (greater maximum surface pressure). Physiological levels of sebum would be expected to expand or fluidize meibum making it spread better and be more surface active (qualities beneficial for tear film stability). Sebum would also be expected to stabilize the tear film lipid layer, which may allow it to withstand the high shear pressure of a blink.

  14. Sebum/Meibum Surface Film Interactions and Phase Transitional Differences

    Science.gov (United States)

    Mudgil, Poonam; Borchman, Douglas; Gerlach, Dylan; Yappert, Marta C.

    2016-01-01

    Purpose Sebum may contribute to the composition of the tear film lipid layer naturally or as a contaminant artifact from collection. The aims of this study were to determine: if sebum changes the rheology of meibum surface films; if the resonance near 5.2 ppm in the 1H-NMR spectra of sebum is due to squalene (SQ); and if sebum or SQ, a major component of sebum, interacts with human meibum. Methods Human meibum was collected from the lid margin with a platinum spatula. Human sebum was collected using lipid absorbent tape. Langmuir trough technology was used to measure the rheology of surface films. Infrared spectroscopy was used to measure lipid conformation and phase transitions. We used 1H-NMR to measure composition and confirm the primary structure of SQ. Results The NMR resonance near 5.2 ppm in the spectra of human sebum was from SQ which composed 28 mole percent of sebum. Both sebum and SQ lowered the lipid order of meibum. Sebum expanded meibum films at lower concentrations and condensed meibum films at higher concentrations. Sebum caused meibum to be more stable at higher pressures (greater maximum surface pressure). Conclusions Physiological levels of sebum would be expected to expand or fluidize meibum making it spread better and be more surface active (qualities beneficial for tear film stability). Sebum would also be expected to stabilize the tear film lipid layer, which may allow it to withstand the high shear pressure of a blink. PMID:27145473

  15. Energy expenditure and sex differences of golf playing.

    Science.gov (United States)

    Zunzer, Stefan C; von Duvillard, Serge P; Tschakert, Gerhard; Mangus, Brent; Hofmann, Peter

    2013-01-01

    The purpose of the study was to assess the average physical intensity and energy expenditure during a single round of golf on hilly and flat courses in a heterogeneous group of healthy men and women of varying age and golf handicap. Forty-two males and 24 females completed an incremental cycle-ergometer exercise test to determine exercise performance markers. The heart rate (HR), duration, distance, walking speed, ascent and descent were measured via a global positioning system (GPS)/HR monitor during the game and energy expenditure was calculated. Playing 9 or 18-holes of golf, independent of the golf course design, the average HR was not significantly different between sexes or the subgroups. The intensities were light with respect to the percentage of maximal HR and metabolic equivalents of task (METs). Total energy expenditure of all participants was not significantly different for hilly (834 ± 344 kcal) vs. flat courses (833 ± 295 kcal) whereas male players expended significantly greater energy than female players (926 ± 292 vs. 556 ± 180 kcal), but did not have significantly greater relative energy expenditure (2.8 ± 0.8 vs. 2.2 ± 0.7 METs). As a high volume physical activity, playing golf is suggested to yield health benefits. Since the intensity was well below recommended limits, golf may have health related benefits unrelated to the intensity level of the activity.

  16. Energy-driven surface evolution in beta-MnO2 structures

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Wentao; Yuan, Yifei; Asayesh-Ardakani, Hasti; Huang, Zhennan; Long, Fei; Friedrich, Craig; Amine, Khalil; Lu, Jun; Shahbazian-Yassar, Reza

    2018-01-01

    Exposed crystal facets directly affect the electrochemical/catalytic performance of MnO2 materials during their applications in supercapacitors, rechargeable batteries, and fuel cells. Currently, the facet-controlled synthesis of MnO2 is facing serious challenges due to the lack of an in-depth understanding of their surface evolution mechanisms. Here, combining aberration-corrected scanning transmission electron microscopy (STEM) and high-resolution TEM, we revealed a mutual energy-driven mechanism between beta-MnO2 nanowires and microstructures that dominated the evolution of the lateral facets in both structures. The evolution of the lateral surfaces followed the elimination of the {100} facets and increased the occupancy of {110} facets with the increase in hydrothermal retention time. Both self-growth and oriented attachment along their {100} facets were observed as two different ways to reduce the surface energies of the beta-MnO2 structures. High-density screw dislocations with the 1/2 < 100 > Burgers vector were generated consequently. The observed surface evolution phenomenon offers guidance for the facet-controlled growth of beta-MnO2 materials with high performances for its application in metal-air batteries, fuel cells, supercapacitors, etc.

  17. Extraction of topographic and material contrasts on surfaces from SEM images obtained by energy filtering detection with low-energy primary electrons.

    Science.gov (United States)

    Nagoshi, Masayasu; Aoyama, Tomohiro; Sato, Kaoru

    2013-01-01

    Secondary electron microscope (SEM) images have been obtained for practical materials using low primary electron energies and an in-lens type annular detector with changing negative bias voltage supplied to a grid placed in front of the detector. The kinetic-energy distribution of the detected electrons was evaluated by the gradient of the bias-energy dependence of the brightness of the images. This is divided into mainly two parts at about 500 V, high and low brightness in the low- and high-energy regions, respectively and shows difference among the surface regions having different composition and topography. The combination of the negative grid bias and the pixel-by-pixel image subtraction provides the band-pass filtered images and extracts the material and topographic information of the specimen surfaces. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. The influence of land surface parameters on energy flux densities derived from remote sensing data

    Energy Technology Data Exchange (ETDEWEB)

    Tittebrand, A.; Schwiebus, A. [Inst. for Hydrology und Meteorology, TU Dresden (Germany); Berger, F.H. [Observatory Lindenberg, German Weather Service, Lindenberg (Germany)

    2005-04-01

    Knowledge of the vegetation properties surface reflectance, normalised difference vegetation index (NDVI) and leaf area index (LAI) are essential for the determination of the heat and water fluxes between terrestrial ecosystems and the atmosphere. Remote sensing data can be used to derive spatial estimates of the required surface properties. The determination of land surface parameters and their influence on radiant and energy flux densities is investigated with data of different remote sensing systems. Sensitivity studies show the importance of correctly derived land surface properties to estimate the key quantity of the hydrological cycle, the evapotranspiration (L.E), most exactly. In addition to variable parameters like LAI or NDVI there are also parameters which are can not be inferred from satellite data but needed for the Penman-Monteith approach. Fixed values are assumed for these variables because they have little influence on L.E. Data of Landsat-7 ETM+ and NOAA-16 AVHRR are used to show results in different spatial resolution. The satellite derived results are compared with ground truth data provided by the Observatory Lindenberg of the German Weather Service. (orig.)

  19. Effect of surface free energies on the heterogeneous nucleation of water droplet: A molecular dynamics simulation approach

    Energy Technology Data Exchange (ETDEWEB)

    Xu, W.; Lan, Z.; Peng, B. L.; Wen, R. F.; Ma, X. H., E-mail: xuehuma@dlut.edu.cn [Liaoning Provincial Key Laboratory of Clean Utilization of Chemical Resources, Institute of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China)

    2015-02-07

    Heterogeneous nucleation of water droplet on surfaces with different solid-liquid interaction intensities is investigated by molecular dynamics simulation. The interaction potentials between surface atoms and vapor molecules are adjusted to obtain various surface free energies, and the nucleation process and wetting state of nuclei on surfaces are investigated. The results indicate that near-constant contact angles are already established for nano-scale nuclei on various surfaces, with the contact angle decreasing with solid-liquid interaction intensities linearly. Meanwhile, noticeable fluctuation of vapor-liquid interfaces can be observed for the nuclei that deposited on surfaces, which is caused by the asymmetric forces from vapor molecules. The formation and growth rate of nuclei are increasing with the solid-liquid interaction intensities. For low energy surface, the attraction of surface atoms to water molecules is comparably weak, and the pre-existing clusters can depart from the surface and enter into the bulk vapor phase. The distribution of clusters within the bulk vapor phase becomes competitive as compared with that absorbed on surface. For moderate energy surfaces, heterogeneous nucleation predominates and the formation of clusters within bulk vapor phase is suppressed. The effect of high energy particles that embedded in low energy surface is also discussed under the same simulation system. The nucleation preferably initiates on the high energy particles, and the clusters that formed on the heterogeneous particles are trapped around their original positions instead of migrating around as that observed on smooth surfaces. This feature makes it possible for the heterogeneous particles to act as fixed nucleation sites, and simulation results also suggest that the number of nuclei increases monotonously with the number of high energy particles. The growth of nuclei on high energy particles can be divided into three sub-stages, beginning with the formation

  20. A = 4 0+ - 1+ binding-energy difference

    International Nuclear Information System (INIS)

    Gibson, B.F.; Lehman, D.R.

    1982-01-01

    The A = 4 Λ-hypernuclei provide a rich source of information about the s-wave properties of the fundamental hyperon-nucleon (YN) force as well as offer a unique opportunity to investigate the complications that arise in calculations of the properties of bound systems in which one baryon (here the Λ) with a given isospin couples strongly to another (the Σ) with a different isospin. The Λ 4 H - Λ 4 He isodoublet ground-state energies are not consistent with a charge symmetry hypothesis for the YN interaction. The (spin-flip) excitation energies are quite sensitive to the ΛN - ΣN coupling of the YN interaction. In particular, when one represents the free YN interaction in terms of one-channel effective ΛN potentials, the resulting 0 + (ground) state and 1 + (excited) spin-flip state are inversely ordered in terms of binding energies, the 1 + state being more bound. It is the Σ suppression that results from the reduced strength of the ΛN - ΣN off-diagonal coupling potential when the trinucleon core is restricted to isospin-1/2 which we study here. We find this spin-isospin suppression of the Λ-Σ conversion, which is due to the composite nature of the nuclear cores of the Λ 4 H and Λ 4 He hypernuclei, to be a significant factor in understanding the 0 + - 1 + binding energy relationship

  1. Surface energy balances of three general circulation models: Current climate and response to increasing atmospheric CO2

    International Nuclear Information System (INIS)

    Gutowski, W.J.; Gutzler, D.S.; Portman, D.; Wang, W.C.

    1988-04-01

    The surface energy balance simulated by state-of-the-art general circulation models at GFDL, GISS and NCAR for climates with current levels of atmospheric CO 2 concentration (control climate) and with twice the current levels. The work is part of an effort sponsored by the US Department of Energy to assess climate simulations produced by these models. The surface energy balance enables us to diagnose differences between models in surface temperature climatology and sensitivity to doubling CO 2 in terms of the processes that control surface temperature. Our analysis compares the simulated balances by averaging the fields of interest over a hierarchy of spatial domains ranging from the entire globe down to regions a few hundred kilometers across

  2. Surface influence on convoy electron emission at low energies

    International Nuclear Information System (INIS)

    Sanchez, E.A.

    1988-01-01

    It is studied the dependence of the production of convoy electrons induced by H + - 60 KeV with surface conditions of Al targets by in situ deposition of Na and O. The conclusion is that convoy electron production increases with the work function of the surface. (A.C.A.S.) [pt

  3. The role of clouds in the surface energy balance over the Amazon forest

    International Nuclear Information System (INIS)

    Eltahir, E.A.B.; Humphries, E.J. Jr.

    1998-01-01

    Deforestation in the Amazon region will initially impact the energy balance at the land surface through changes in land cover and surface hydrology. However, continuation of this human activity will eventually lead to atmospheric feedbacks, including changes in cloudiness which may play an important role in the final equilibrium of solar and terrestrial radiation at the surface. In this study, the different components of surface radiation over an undisturbed forest in the Amazon region are computed using data from the Amazon region micrometerological experiment (ARME). Several measures of cloudiness are defined: two estimated from the terrestrial radiation measurements, and one from the solar radiation measurements. The sensitivity of the surface fluxes of solar and terrestrial radiation to natural variability in cloudiness is investigated to infer the potential role of the cloudiness feedback in the surface energy balance. The results of this analysis indicate that a 1% decrease in cloudiness would increase net solar radiation by ca. 1.6 W/m 2 . However, the overall magnitude of this feedback, due to total deforestation of the Amazon forest, is likely to be of the same order as the magnitude of the decrease in net solar radiation due to the observed increase in surface albedo following deforestation. Hence, the total change in net solar radiation is likely to have a negligible magnitude. In contrast to this conclusion, we find that terrestrial radiation is likely to be more strongly affected; reduced cloudiness will decrease net terrestrial radiation; a 1% decrease in cloudiness induces a reduction in net terrestrial radiation of ca. 0.7 W/m 2 ; this process augments the similar effects of the predicted warming and drying in the boundary layer. Due to the cloudiness feedback, the most significant effect of large-scale deforestation on the surface energy balance is likely to be in the modification of the terrestrial radiation field rather than the classical albedo

  4. Medical risks presented by different types of energy

    Energy Technology Data Exchange (ETDEWEB)

    1980-03-01

    This article reports on discussions held during the conference which took place in Paris from 24th to 28th January 1980 and covered the following topics:- The risk concept from the point of view of the epidemiologist and the engineer - perception of the risk. The gulf which exists between the objective risk and that perceived by the public. The need to realize this phenomenon. The particular problems of each type of energy: coal (industrial diseases) - oil - gas - nuclear power (irradiation). Long-term effects and problems: air pollution and effects on health, the growth effect on stocks of atmospheric carbon, water pollution. The methodology of comparative studies of the risks presented by different types of energy. (In French)

  5. Surface structure determinations of crystalline ionic thin films grown on transition metal single crystal surfaces by low energy electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Joel Glenn [Univ. of California, Berkeley, CA (United States)

    2000-05-01

    The surface structures of NaCl(100), LiF(100) and alpha-MgCl2(0001) adsorbed on various metal single crystals have been determined by low energy electron diffraction (LEED). Thin films of these salts were grown on metal substrates by exposing the heated metal surface to a molecular flux of salt emitted from a Knudsen cell. This method of investigating thin films of insulators (ionic salts) on a conducting substrate (metal) circumvents surface charging problems that plagued bulk studies, thereby allowing the use of electron-based techniques to characterize the surface.

  6. Collisions of polyatomic ions with surfaces: incident energy partitioning and chemical reactions

    International Nuclear Information System (INIS)

    Zabka, J.; Roithova, J.; Dolejsek, Z.; Herman, Z.

    2002-01-01

    Collision of polyatomic ions with surfaces were investigated in ion-surface scattering experiments to obtain more information on energy partitioning in ion-surface collision and on chemical reactions at surfaces. Mass spectra, translation energy and angular distributions of product ions were measured in dependence on the incident energy and the incident angle of polyatomic projectiles. From these data distributions of energy fractions resulting in internal excitation of the projectile, translation energy of the product ions, and energy absorbed by the surface were determined. The surface investigated were a standard stainless steel surface, covered by hydrocarbons, carbon surfaces at room and elevated temperatures, and several surfaces covered by a self-assembled monolayers (C 12 -hydrocarbon SAM, C 11 -perfluorohydrocarbon SAM, and C 11 hydrocarbon with terminal -COOH group SAM). The main processes observed at collision energies of 10 - 50 eV were: neutralization of the ions at surfaces, inelastic scattering and dissociations of the projectile ions, quasi elastic scattering of the projectile ions, and chemical reactions with the surface material (usually hydrogen-atom transfer reactions). The ion survival factor was estimated to be a few percent for even-electron ions (like protonated ethanol ion, C 2 H 5 O + , CD 5 + ) and about 10 - 10 2 times lower for radical ions (like ethanol and benzene molecular ions, CD 4 + ). In the polyatomic ion -surface energy transfer experiments, the ethanol molecular ion was used as a well-characterized projectile ion. The results with most of the surfaces studied showed in the collision energy range of 13 - 32 eV that most collisions were strongly inelastic with about 6 - 8 % of the incident projectile energy transformed into internal excitation of the projectile (independent of the incident angle) and led partially to its further dissociation in a unimolecular way after the interaction with the surface. The incident energy

  7. Testing Convergence of Different Free-Energy Methods in a Simple Analytical System with Hidden Barriers

    Directory of Open Access Journals (Sweden)

    S. Alexis Paz

    2018-03-01

    Full Text Available In this work, we study the influence of hidden barriers on the convergence behavior of three free-energy calculation methods: well-tempered metadynamics (WTMD, adaptive-biasing forces (ABF, and on-the-fly parameterization (OTFP. We construct a simple two-dimensional potential-energy surfaces (PES that allows for an exact analytical result for the free-energy in any one-dimensional order parameter. Then we chose different CV definitions and PES parameters to create three different systems with increasing sampling challenges. We find that all three methods are not greatly affected by the hidden-barriers in the simplest case considered. The adaptive sampling methods show faster sampling while the auxiliary high-friction requirement of OTFP makes it slower for this case. However, a slight change in the CV definition has a strong impact in the ABF and WTMD performance, illustrating the importance of choosing suitable collective variables.

  8. Influence of milling process in the surface energy of glass tile frits

    International Nuclear Information System (INIS)

    Tamayo, A.; Rubio, F.; Otero, J. L.; Rubio, J.

    2013-01-01

    In this work has been studied the influence of the milling process of two ceramic frits used in the ceramic tile industry. Both glass frits were of similar chemical composition changing SiO 2 by 5% of B 2 O 3 and both of them were water or dry milled. Glass frit surfaces were characterized by FT-IR, Karl-Fischer (K-F) titration and Inverse Gas Chromatography at Infinite Dilution (IGC-ID). By K-F titration it was observed that water milled frits presented 28 and 26 OH groups for 100 A 2 if they do not contain or contain boron, respectively. These surface changes are also observed by IGC-ID. Thus, the glass frit without boron and dry milled presented the highest dispersive surface energy (44 mJ.m - 2) and the less acidic constant (0.13 kJ.mol - 1). Both glass frits are amphoteric with acidic and base surface active sites, and that frit without boron presents the higher basicity. Milling process influences in the acid-base surface characteristics of both frits by increasing the basicity for the one without boron and increasing for the other one. This has been assigned to the different location of hydroxyl groups where the higher interaction is the one that does not contain boron and dry milled as K-F results. (Author)

  9. Analysis of Energy Demand for Low-Energy Multi-Dwelling Buildings of Different Configuration

    Directory of Open Access Journals (Sweden)

    Giedrė Streckienė

    2014-10-01

    Full Text Available To meet the goals established by Directive 2010/31/EU of the European Parliament and of the Council on the energy performance of buildings, the topics of energy efficiency in new and old buildings must be solved. Research and development of new energy solutions and technology are necessary for increasing energy performance of buildings. Three low-energy multi-dwelling buildings have been modelled and analyzed in the presented study. All multi-dwelling houses are made of similar single-family house cells. However, multi-dwelling buildings are of different geometry, flat number and height. DesignBuilder software was used for simulating and determining heating, cooling and electricity demand for buildings. Three different materials (silicate, ceramic and clay concrete blocks as bearing constructions of external walls have been analyzed. To decrease cooling demand for buildings, the possibility of mounting internal or external louvers has been considered. Primary energy savings for multi-dwelling buildings using passive solar measures have been determined.

  10. Manufacture of nanosized apatite coatings on titanium with different surface treatments using a supersaturated calcification solution

    Directory of Open Access Journals (Sweden)

    Adrian Paz Ramos

    Full Text Available The biomimetic method is used for the deposition of calcium phosphate coatings (Ca - P on the surface of different biomaterials. However, the application of this method requires long exposure times in order to obtain a suitable layer thickness for its use in medical devices. In this paper, we present a fast approach to obtain apatite coatings on titanium, using a combination of supersaturated calcification solution (SCS with chemical modification of the titanium surface. Also, it was evaluated the effect of four different surface treatments on the apatite deposition rate. Commercially pure titanium plates were activated by chemical or thermochemical treatments. Then, the activated samples were immersed in a solution with high content of calcium and phosphate ions at 37 ºC for 24 h, mimicking the physiological conditions. The coatings were studied by Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, scanning electron microscopy (SEM and energy dispersive X-ray spectroscopy (EDX. The use of SCS solutions allowed the formation of crystalline hydroxyapatite coatings within a period of 24 h with a thickness between 1 and 5.3 µm. Besides, precipitates of hydroxyapatite nanoparticles with a globular configuration, forming aggregates with submicrometer size, were found in SCS solutions.

  11. Sebum/Meibum Surface Film Interactions and Phase Transitional Differences

    OpenAIRE

    Mudgil, Poonam; Borchman, Douglas; Gerlach, Dylan; Yappert, Marta C.

    2016-01-01

    Purpose Sebum may contribute to the composition of the tear film lipid layer naturally or as a contaminant artifact from collection. The aims of this study were to determine: if sebum changes the rheology of meibum surface films; if the resonance near 5.2 ppm in the 1H-NMR spectra of sebum is due to squalene (SQ); and if sebum or SQ, a major component of sebum, interacts with human meibum. Methods Human meibum was collected from the lid margin with a platinum spatula. Human sebum was collecte...

  12. Properties of water surface discharge at different pulse repetition rates

    Czech Academy of Sciences Publication Activity Database

    Ruma, R.; Hosseini, S.H.R.; Yoshihara, K.; Akiyama, M.; Sakugawa, T.; Lukeš, Petr; Akiyama, H.

    2014-01-01

    Roč. 116, č. 12 (2014), s. 123304-123304 ISSN 0021-8979 Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100431203 Program:M Institutional support: RVO:61389021 Keywords : plasma in air * water surface discharge * pulse frequency * hydrogen peroxide * organic dye Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.183, year: 2014 http://dx.doi.org/ 10.1063/1.4896266

  13. Full energy chain analysis of greenhouse gas emissions from different energy sources

    International Nuclear Information System (INIS)

    Vate, J.F. van de

    1996-01-01

    The field of work of the Advisory Group Meeting/Workshop, i.e. full-energy chain emissions of greenhouse gases, is defined, and its environment, i.e. the Earth Summit -the 1992 UN Conference on Environment and Development in Rio-, is discussed. It is inferred that countries that ratified the Earth Summit's Convention on Climate Change have committed themselves to lower the greenhouse gas emissions from their energy use, and that this can be done most effectively by accounting in energy planning for the full-energy chain emissions of all greenhouse gases. The scatter in literature values of greenhouse gas emission factors of the full energy chain of individual energy sources is discussed. The scatter among others is due to different analytical methods, data bases and system boundaries, and due to neglect of the non-CO 2 greenhouse gases and professional biases. Generic values for greenhouse gas emission factors of energy and materials use are proposed. (author). 10 refs, 2 tabs

  14. 3D Printed Potential and Free Energy Surfaces for Teaching Fundamental Concepts in Physical Chemistry

    Science.gov (United States)

    Kaliakin, Danil S.; Zaari, Ryan R.; Varganov, Sergey A.

    2015-01-01

    Teaching fundamental physical chemistry concepts such as the potential energy surface, transition state, and reaction path is a challenging task. The traditionally used oversimplified 2D representation of potential and free energy surfaces makes this task even more difficult and often confuses students. We show how this 2D representation can be…

  15. Ab Initio and DFT Potential Energy Surfaces for Cyanuric Chloride Reactions

    National Research Council Canada - National Science Library

    Pai, Sharmila

    1998-01-01

    ... on the potential energy surface were calculated using the 6-31G and 6-311 +Gbasis sets. DFT(B3LYP) geometry optimizations and zero-point corrections for critical points on the potential energy surface were calculated with the 6-31G, 6-311...

  16. Hot-electron-mediated desorption rates calculated from excited-state potential energy surfaces

    DEFF Research Database (Denmark)

    Olsen, Thomas; Gavnholt, Jeppe; Schiøtz, Jakob

    2009-01-01

    We present a model for desorption induced by (multiple) electronic transitions [DIET (DIMET)] based on potential energy surfaces calculated with the delta self-consistent field extension of density-functional theory. We calculate potential energy surfaces of CO and NO molecules adsorbed on variou...

  17. Cluster ion-surface interactions: from meV to MeV energies

    Energy Technology Data Exchange (ETDEWEB)

    Nordlund, Kai; Meinander, Kristoffer; Jaervi, Tommi T.; Peltola, Jarkko; Samela, Juha [Accelerator Laboratory, University of Helsinki (Finland)

    2008-07-01

    The nature of cluster ion-surface interactions changes dramatically with the kinetic energy of the incoming cluster species. In this talk I review some of our recent work on the nature of cluster-surface interactions spanning an energy range from a few MeV/cluster to about 1 MeV/cluster and cluster sizes in the range of 10 - 1000 atoms/cluster. In the energy range of a few MeV/cluster ion, the kinetic energy of the incoming ion is insignificant compared to the energy gained when the surface potential energy at the cluster-surface interface is released and partly translated into kinetic energy. Even in this energy regime I show that surprisingly drastic effects can occur. When the energy of the incoming cluster is raised to a few eV/atom, the kinetic energy of the incoming cluster starts to affect the deposition. It will cause the cluster to entirely reform on impact. When the energy is raised to the range of keV's/cluster, the clusters start to penetrate the sample, fairly similar to conventional ion implantation. However, in dense targets the cluster ions may stick close to each other long enough to cause a significant enhancement of the heat spike in the material. Finally, I show that at kinetic energies around 1 MeV/cluster the cluster enhancement of the heat spike may lead to dramatic surface effects.

  18. Structure of production costs of different energy sources (fossile fuels and nuclear energy) (group 11)

    International Nuclear Information System (INIS)

    Girard, Ph.

    2002-01-01

    This article is the work of a group of students from the ''Ecole Nationale d'Administration'', they had to study the structure of the costs of the different energy sources. This analysis shows some common features between the energy sources. The cost is very dependent on the partial costs of technological constraints due to exploration, production, transport and distribution. For primary energies the market appears to be not very competitive, the price depends strongly on the market power of the operator and benefits are generally important. In France, taxes play a role to assure competitiveness of gas and coal against oil. Uranium fuel presents the lowest production and transformation costs at the same energy content. Transport costs are important for natural gas which implies a strong mutual dependence between gas producers and consumers. The irreplaceable use of oil in transport assures regular high revenues for oil companies. (A.C.)

  19. Impact of Land Cover Change Induced by a Fire Event on the Surface Energy Fluxes Derived from Remote Sensing

    Directory of Open Access Journals (Sweden)

    Juan M. Sánchez

    2015-11-01

    Full Text Available Forest fires affect the natural cycle of the vegetation, and the structure and functioning of ecosystems. As a consequence of defoliation and vegetation mortality, surface energy flux patterns can suffer variations. Remote sensing techniques together with surface energy balance modeling offer the opportunity to explore these changes. In this paper we focus on a Mediterranean forest ecosystem. A fire event occurred in 2001 in Almodóvar del Pinar (Spain affecting a pine and shrub area. A two-source energy balance approach was applied to a set of Landsat 5-TM and Landsat 7-EMT+ images to estimate the surface fluxes in the area. Three post-fire periods were analyzed, six, seven, nine, and 11 years after the fire event. Results showed the regeneration of the shrub area in 6–7 years, in contrast to the pine area, where an important decrease in evapotranspiration, around 1 mm·day−1, remained. Differences in evapotranspiration were mitigated nine and 11 years after the fire in the pine area, whereas significant deviations in the rest of the terms of the energy balance equation were still observed. The combined effect of changes in the vegetation structure and surface variables, such as land surface temperature, albedo, or vegetation coverage, is responsible for these variations in the surface energy flux patterns.

  20. Comparison of Four Different Energy Balance Models for Estimating Evapotranspiration in the Midwestern United States

    Directory of Open Access Journals (Sweden)

    Ramesh K. Singh

    2015-12-01

    Full Text Available The development of different energy balance models has allowed users to choose a model based on its suitability in a region. We compared four commonly used models—Mapping EvapoTranspiration at high Resolution with Internalized Calibration (METRIC model, Surface Energy Balance Algorithm for Land (SEBAL model, Surface Energy Balance System (SEBS model, and the Operational Simplified Surface Energy Balance (SSEBop model—using Landsat images to estimate evapotranspiration (ET in the Midwestern United States. Our models validation using three AmeriFlux cropland sites at Mead, Nebraska, showed that all four models captured the spatial and temporal variation of ET reasonably well with an R2 of more than 0.81. Both the METRIC and SSEBop models showed a low root mean square error (<0.93 mm·day−1 and a high Nash–Sutcliffe coefficient of efficiency (>0.80, whereas the SEBAL and SEBS models resulted in relatively higher bias for estimating daily ET. The empirical equation of daily average net radiation used in the SEBAL and SEBS models for upscaling instantaneous ET to daily ET resulted in underestimation of daily ET, particularly when the daily average net radiation was more than 100 W·m−2. Estimated daily ET for both cropland and grassland had some degree of linearity with METRIC, SEBAL, and SEBS, but linearity was stronger for evaporative fraction. Thus, these ET models have strengths and limitations for applications in water resource management.

  1. Energy savings due to building insulation of different thickness

    Directory of Open Access Journals (Sweden)

    Orzechowski Tadeusz

    2017-01-01

    Full Text Available In the plans of thermo-modernisation of historic buildings, strict requirements on energy performance are often relaxed. Detailed analyses are performed to select thermal upgrading technology that would ensure maximum environmental benefits while preserving the historic value of the building. The analysis of the costs of thermal upgrading with the use of heat-preserving plasters having different insulation properties is made for a coal-fired boiler plant. Optimal and advantageous ranges of insulation materials application are shown in reference to coal savings in boilers with variable and constant efficiency. Climatic conditions and environmental benefits are indicated.

  2. Comparison of surface freshwater fluxes from different climate forecasts produced through different ensemble generation schemes.

    Science.gov (United States)

    Romanova, Vanya; Hense, Andreas; Wahl, Sabrina; Brune, Sebastian; Baehr, Johanna

    2016-04-01

    The decadal variability and its predictability of the surface net freshwater fluxes is compared in a set of retrospective predictions, all using the same model setup, and only differing in the implemented ocean initialisation method and ensemble generation method. The basic aim is to deduce the differences between the initialization/ensemble generation methods in view of the uncertainty of the verifying observational data sets. The analysis will give an approximation of the uncertainties of the net freshwater fluxes, which up to now appear to be one of the most uncertain products in observational data and model outputs. All ensemble generation methods are implemented into the MPI-ESM earth system model in the framework of the ongoing MiKlip project (www.fona-miklip.de). Hindcast experiments are initialised annually between 2000-2004, and from each start year 10 ensemble members are initialized for 5 years each. Four different ensemble generation methods are compared: (i) a method based on the Anomaly Transform method (Romanova and Hense, 2015) in which the initial oceanic perturbations represent orthogonal and balanced anomaly structures in space and time and between the variables taken from a control run, (ii) one-day-lagged ocean states from the MPI-ESM-LR baseline system (iii) one-day-lagged of ocean and atmospheric states with preceding full-field nudging to re-analysis in both the atmospheric and the oceanic component of the system - the baseline one MPI-ESM-LR system, (iv) an Ensemble Kalman Filter (EnKF) implemented into oceanic part of MPI-ESM (Brune et al. 2015), assimilating monthly subsurface oceanic temperature and salinity (EN3) using the Parallel Data Assimilation Framework (PDAF). The hindcasts are evaluated probabilistically using fresh water flux data sets from four different reanalysis data sets: MERRA, NCEP-R1, GFDL ocean reanalysis and GECCO2. The assessments show no clear differences in the evaluations scores on regional scales. However, on the

  3. Dispersion and energy conservation relations of surface waves in semi-infinite plasma

    International Nuclear Information System (INIS)

    Atanassov, V.

    1981-01-01

    The hydrodynamic theory of surface wave propagation in semi-infinite homogeneous isotropic plasma is considered. Explicit linear surface wave solutions are given for the electric and magnetic fields, charge and current densities. These solutions are used to obtain the well-known dispersion relations and, together with the general energy conservation equation, to find appropriate definitions for the energy and the energy flow densities of surface waves. These densities are associated with the dispersion relation and the group velocity by formulae similar to those for bulk waves in infinite plasmas. Both cases of high-frequency (HF) and low-frequency (LF) surface waves are considered. (author)

  4. Converting chemical energy into electricity through a functionally cooperating device with diving-surfacing cycles.

    Science.gov (United States)

    Song, Mengmeng; Cheng, Mengjiao; Ju, Guannan; Zhang, Yajun; Shi, Feng

    2014-11-05

    A smart device that can dive or surface in aqueous medium has been developed by combining a pH-responsive surface with acid-responsive magnesium. The diving-surfacing cycles can be used to convert chemical energy into electricity. During the diving-surfacing motion, the smart device cuts magnetic flux lines and produces a current, demonstrating that motional energy can be realized by consuming chemical energy of magnesium, thus producing electricity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Uncertainty analysis of the Operational Simplified Surface Energy Balance (SSEBop) model at multiple flux tower sites

    Science.gov (United States)

    Chen, Mingshi; Senay, Gabriel B.; Singh, Ramesh K.; Verdin, James P.

    2016-01-01

    Evapotranspiration (ET) is an important component of the water cycle – ET from the land surface returns approximately 60% of the global precipitation back to the atmosphere. ET also plays an important role in energy transport among the biosphere, atmosphere, and hydrosphere. Current regional to global and daily to annual ET estimation relies mainly on surface energy balance (SEB) ET models or statistical and empirical methods driven by remote sensing data and various climatological databases. These models have uncertainties due to inevitable input errors, poorly defined parameters, and inadequate model structures. The eddy covariance measurements on water, energy, and carbon fluxes at the AmeriFlux tower sites provide an opportunity to assess the ET modeling uncertainties. In this study, we focused on uncertainty analysis of the Operational Simplified Surface Energy Balance (SSEBop) model for ET estimation at multiple AmeriFlux tower sites with diverse land cover characteristics and climatic conditions. The 8-day composite 1-km MODerate resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) was used as input land surface temperature for the SSEBop algorithms. The other input data were taken from the AmeriFlux database. Results of statistical analysis indicated that the SSEBop model performed well in estimating ET with an R2 of 0.86 between estimated ET and eddy covariance measurements at 42 AmeriFlux tower sites during 2001–2007. It was encouraging to see that the best performance was observed for croplands, where R2 was 0.92 with a root mean square error of 13 mm/month. The uncertainties or random errors from input variables and parameters of the SSEBop model led to monthly ET estimates with relative errors less than 20% across multiple flux tower sites distributed across different biomes. This uncertainty of the SSEBop model lies within the error range of other SEB models, suggesting systematic error or bias of the SSEBop model is within

  6. Vibrational effects on surface energies and band gaps in hexagonal and cubic ice

    International Nuclear Information System (INIS)

    Engel, Edgar A.; Needs, Richard J.; Monserrat, Bartomeu

    2016-01-01

    Surface energies of hexagonal and cubic water ice are calculated using first-principles quantum mechanical methods, including an accurate description of anharmonic nuclear vibrations. We consider two proton-orderings of the hexagonal and cubic ice basal surfaces and three proton-orderings of hexagonal ice prism surfaces, finding that vibrations reduce the surface energies by more than 10%. We compare our vibrational densities of states to recent sum frequency generation absorption measurements and identify surface proton-orderings of experimental ice samples and the origins of characteristic absorption peaks. We also calculate zero point quantum vibrational corrections to the surface electronic band gaps, which range from −1.2 eV for the cubic ice basal surface up to −1.4 eV for the hexagonal ice prism surface. The vibrational corrections to the surface band gaps are up to 12% smaller than for bulk ice.

  7. Performance Improvement of Polymer Solar Cells by Surface-Energy-Induced Dual Plasmon Resonance.

    Science.gov (United States)

    Yao, Mengnan; Shen, Ping; Liu, Yan; Chen, Boyuan; Guo, Wenbin; Ruan, Shengping; Shen, Liang

    2016-03-09

    The surface plasmon resonance (SPR) effect of metal nanoparticles (MNPs) is effectively applied on polymer solar cells (PSCs) to improve power conversion efficiency (PCE). However, universality of the reported results mainly focused on utilizing single type of MNPs to enhance light absorption only in specific narrow wavelength range. Herein, a surface-energy-induced dual MNP plasmon resonance by thermally evaporating method was presented to achieve the absorption enhancement in wider range. The differences of surface energy between silver (Ag), gold (Au), and tungsten trioxide (WO3) compared by contact angle images enable Ag and Au prefer to respectively aggregate into isolated islands rather than films at the initial stage of the evaporation process, which was clearly demonstrated in the atomic force microscopy (AFM) measurement. The sum of plasmon-enhanced wavelength range induced by both Ag NPs (350-450 nm) and Au NPs (450-600 nm) almost cover the whole absorption spectra of active layers, which compatibly contribute a significant efficiency improvement from 4.57 ± 0.16 to 6.55 ± 0.12% compared to the one without MNPs. Besides, steady state photoluminescence (PL) measurements provide strong evidence that the SPR induced by the Ag-Au NPs increase the intensity of light absorption. Finally, ultraviolet photoelectron spectroscopy (UPS) reveals that doping Au and Ag causes upper shift of both the work function and valence band of WO3, which is directly related to hole collection ability. We believe the surface-energy-induced dual plasmon resonance enhancement by simple thermally evaporating technique might pave the way toward higher-efficiency PSCs.

  8. Surface energy exchanges over contrasting vegetation types on a subtropical sand island

    Science.gov (United States)

    Gray, Michael; McGowan, Hamish; Lowry, Andrew; Guyot, Adrien

    2017-04-01

    The surface energy balance of subtropical coastal vegetation communities has thus far received little attention. Here we present a multi-year observational data set using the eddy covariance method to quantify for the first time the surface energy balance over three contrasting vegetation types on a subtropical sand island in eastern Australia: a periodically inundated sedge swamp, an exotic pine plantation and a coastal heath. Maximum daily sensible heat flux varied between sites but was typically > 280 Wm-2 in the coastal heath and pine plantation but no more than 250 Wm-2 in the swamp when dry and 1. The partitioning of energy, as represented by β, is similar to a variety of Australian ecosystems, and a range of coastal vegetation types in other latitudes, but differs from other tropical or subtropical locations which have strongly seasonal rainfall patterns and therefore a switch from β > 1 before rainfall to β changes in background meteorology with the most important influences being net radiation, absolute humidity, and rainfall. The main factor differentiating the sites was soil water content, with the remnant coastal heath and swamp having ready access to water but the exotic pine plantation having much drier soils. Should the current balance between remnant vegetation and the pine plantation undergo changes there would be a corresponding shift in the surface energy balance of the island as a whole, and altered plant water use may lead to reduced water table depth, important because the groundwater of the local islands is used as part of a regional water grid. A better understanding of the response of coastal vegetation to atmospheric forcing will enable more informed decision making on land use changes, as coastal regions the world over face development pressure.

  9. Energy difference and energy of mixing for crystalline structures of Ni-Ti-Mo alloys

    International Nuclear Information System (INIS)

    Skorentsev, L.F.; Demidenko, V.S.

    1995-01-01

    Using the locator variant of the coherent potential method combined with the canonical d band approximation, we have obtained the energy characteristics of molybdenum-containing titanium nickelide alloys for real and virtual high-symmetry crystalline phases. We have analyzed the reasons implied by the calculation results for the difference in the properties of molybdenum- and iron-containing alloys

  10. Surface wave energy absorption by a partially submerged bio-inspired canopy.

    Science.gov (United States)

    Nové-Josserand, C; Castro Hebrero, F; Petit, L-M; Megill, W M; Godoy-Diana, R; Thiria, B

    2018-03-27

    Aquatic plants are known to protect coastlines and riverbeds from erosion by damping waves and fluid flow. These flexible structures absorb the fluid-borne energy of an incoming fluid by deforming mechanically. In this paper we focus on the mechanisms involved in these fluid-elasticity interactions, as an efficient energy harvesting system, using an experimental canopy model in a wave tank. We study an array of partially-submerged flexible structures that are subjected to the action of a surface wave field, investigating in particular the role of spacing between the elements of the array on the ability of our system to absorb energy from the flow. The energy absorption potential of the canopy model is examined using global wave height measurements for the wave field and local measurements of the elastic energy based on the kinematics of each element of the canopy. We study different canopy arrays and show in particular that flexibility improves wave damping by around 40%, for which half is potentially harvestable.

  11. Physical and chemical nature of the scaling relations between adsorption energies of atoms on metal surfaces

    DEFF Research Database (Denmark)

    Calle-Vallejo, F.; Martínez, J. I.; García Lastra, Juan Maria

    2012-01-01

    phenomenon between any set of adsorbates bound similarly to the surface. On the example of the near-surface alloys of Pt, we show that scalability is a result of identical variations of adsorption energies with respect to the valence configuration of both the surface components and the adsorbates....

  12. Role of particle-hole symmetry in mirror energy difference

    International Nuclear Information System (INIS)

    Kumar, V.; Kumar, S.; Hasan, Z.; Kumar, D.; Koranga, B.S.; Rohitash; Singh, D.; Negi, D.; Angus, L.

    2011-01-01

    Charge symmetry between protons and neutrons means that they can be viewed as two states of the same particle, the nucleon, characterized by different projections of the isospin quantum number. In the hypothesis of charge symmetry expected identical behaviour of excited states of two nuclei with the same total number of nucleons (isobaric nuclei). The nuclei with magic number are considered to be spherical. When the number of particles/holes increase, the nucleus try towards more deformed upto mid-shell. It shows symmetry between particles and holes towards the deformation. The hypothesis of Particle-hole symmetry expected identical behaviour of excited states of two nuclei close to magic number. It is worthwhile to examine the shape of mirror energy difference (MED) close to magic number nuclei, which will also an example of particle-hole symmetry

  13. Energy Fluxes above Three Disparate Surfaces in a Temperate Mesoscale Coastal Catchment

    DEFF Research Database (Denmark)

    Ringgaard, Rasmus; Herbst, Mathias; Friborg, Thomas

    2011-01-01

    This study is part of the long-term catchment-scale hydrological observatory, HOBE, situated in the Skjern River catchment covering 2500 km2 on the western coast of Denmark. To gain a more detailed knowledge of how evapotranspiration is controlled by the local surface and atmospheric processes......, eddy-covariance systems have been installed over an agricultural field, over a spruce [Picea abies (L.) H. Karst.] plantation, and on wet grassland. Measurements started in fall 2008, and the first annual series showed large differences in evaporative response among the surfaces. The annual sum...... was about 500 mm for the wet grassland and spruce plantation, while it was about 300 mm for the irrigated agricultural site. In winter, the actual evapotranspiration rate of the grassland and the forest were much larger than the available energy evaluated from the radiation balance, while at the same time...

  14. Estimating radiative feedbacks from stochastic fluctuations in surface temperature and energy imbalance

    Science.gov (United States)

    Proistosescu, C.; Donohoe, A.; Armour, K.; Roe, G.; Stuecker, M. F.; Bitz, C. M.

    2017-12-01

    Joint observations of global surface temperature and energy imbalance provide for a unique opportunity to empirically constrain radiative feedbacks. However, the satellite record of Earth's radiative imbalance is relatively short and dominated by stochastic fluctuations. Estimates of radiative feedbacks obtained by regressing energy imbalance against surface temperature depend strongly on sampling choices and on assumptions about whether the stochastic fluctuations are primarily forced by atmospheric or oceanic variability (e.g. Murphy and Forster 2010, Dessler 2011, Spencer and Braswell 2011, Forster 2016). We develop a framework around a stochastic energy balance model that allows us to parse the different contributions of atmospheric and oceanic forcing based on their differing impacts on the covariance structure - or lagged regression - of temperature and radiative imbalance. We validate the framework in a hierarchy of general circulation models: the impact of atmospheric forcing is examined in unforced control simulations of fixed sea-surface temperature and slab ocean model versions; the impact of oceanic forcing is examined in coupled simulations with prescribed ENSO variability. With the impact of atmospheric and oceanic forcing constrained, we are able to predict the relationship between temperature and radiative imbalance in a fully coupled control simulation, finding that both forcing sources are needed to explain the structure of the lagged-regression. We further model the dependence of feedback estimates on sampling interval by considering the effects of a finite equilibration time for the atmosphere, and issues of smoothing and aliasing. Finally, we develop a method to fit the stochastic model to the short timeseries of temperature and radiative imbalance by performing a Bayesian inference based on a modified version of the spectral Whittle likelihood. We are thus able to place realistic joint uncertainty estimates on both stochastic forcing and

  15. Molecular dynamics simulation of temperature effects on low energy near-surface cascades and surface damage in Cu

    Science.gov (United States)

    Zhu, Guo; Sun, Jiangping; Guo, Xiongxiong; Zou, Xixi; Zhang, Libin; Gan, Zhiyin

    2017-06-01

    The temperature effects on near-surface cascades and surface damage in Cu(0 0 1) surface under 500 eV argon ion bombardment were studied using molecular dynamics (MD) method. In present MD model, substrate system was fully relaxed for 1 ns and a read-restart scheme was introduced to save total computation time. The temperature dependence of damage production was calculated. The evolution of near-surface cascades and spatial distribution of adatoms at varying temperature were analyzed and compared. It was found that near-surface vacancies increased with temperature, which was mainly due to the fact that more atoms initially located in top two layers became adatoms with the decrease of surface binding energy. Moreover, with the increase of temperature, displacement cascades altered from channeling-like structure to branching structure, and the length of collision sequence decreased gradually, because a larger portion of energy of primary knock-on atom (PKA) was scattered out of focused chain. Furthermore, increasing temperature reduced the anisotropy of distribution of adatoms, which can be ascribed to that regular registry of surface lattice atoms was changed with the increase of thermal vibration amplitude of surface atoms.

  16. Molecular dynamics simulation of temperature effects on low energy near-surface cascades and surface damage in Cu

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Guo; Sun, Jiangping; Guo, Xiongxiong; Zou, Xixi; Zhang, Libin; Gan, Zhiyin, E-mail: ganzhiyin@126.com

    2017-06-15

    The temperature effects on near-surface cascades and surface damage in Cu(0 0 1) surface under 500 eV argon ion bombardment were studied using molecular dynamics (MD) method. In present MD model, substrate system was fully relaxed for 1 ns and a read-restart scheme was introduced to save total computation time. The temperature dependence of damage production was calculated. The evolution of near-surface cascades and spatial distribution of adatoms at varying temperature were analyzed and compared. It was found that near-surface vacancies increased with temperature, which was mainly due to the fact that more atoms initially located in top two layers became adatoms with the decrease of surface binding energy. Moreover, with the increase of temperature, displacement cascades altered from channeling-like structure to branching structure, and the length of collision sequence decreased gradually, because a larger portion of energy of primary knock-on atom (PKA) was scattered out of focused chain. Furthermore, increasing temperature reduced the anisotropy of distribution of adatoms, which can be ascribed to that regular registry of surface lattice atoms was changed with the increase of thermal vibration amplitude of surface atoms.

  17. Climate-induced hotspots in surface energy fluxes from 1948 to 2000

    International Nuclear Information System (INIS)

    Sheng Li; Liu Shuhua; Liu Heping

    2010-01-01

    Understanding how land surfaces respond to climate change requires knowledge of land-surface processes, which control the degree to which interannual variability and mean trends in climatic variables affect the surface energy budget. We use the latest version of the Community Land Model version 3.5 (CLM3.5), which is driven by the latest updated hybrid reanalysis-observation atmospheric forcing dataset constructed by Princeton University, to obtain global distributions of the surface energy budget from 1948 to 2000. We identify climate change hotspots and surface energy flux hotspots from 1948 to 2000. Surface energy flux hotspots, which reflect regions with strong changes in surface energy fluxes, reveal seasonal variations with strong signals in winter, spring, and autumn and weak ones in summer. Locations for surface energy flux hotspots are not, however, fully linked with those for climate change hotspots, suggesting that only in some regions are land surfaces more responsive to climate change in terms of interannual variability and mean trends.

  18. Quantum Mechanical Determination of Potential Energy Surfaces for TiO and H2O

    Science.gov (United States)

    Langhoff, Stephen R.

    1996-01-01

    We discuss current ab initio methods for determining potential energy surfaces, in relation to the TiO and H2O molecules, both of which make important contributions to the opacity of oxygen-rich stars. For the TiO molecule we discuss the determination of the radiative lifetimes of the excited states and band oscillator strengths for both the triplet and singlet band systems. While the theoretical radiative lifetimes for TiO agree well with recent measurements, the band oscillator strengths differ significantly from those currently employed in opacity calculations. For the H2O molecule we discuss the current results for the potential energy and dipole moment ground state surfaces generated at NASA Ames. We show that it is necessary to account for such effects as core-valence Correlation energy to generate a PES of near spectroscopic accuracy. We also describe how we solve the ro-vibrational problem to obtain the line positions and intensities that are needed for opacity sampling.

  19. Accurate adiabatic energy surfaces for the ground and first excited states of He2+

    International Nuclear Information System (INIS)

    Lee, E.P.F.

    1993-01-01

    Different factors affecting the accuracy of the computed energy surfaces of the ground and first excited state of He 2 + have been examined, including the choice of the one-and many-particle bases, the configurational space in the MRCI (multi-reference configuration interaction) calculations and other corrections such as the Davidson and the full counterpoise (CP) correction. From basis-variation studies, it was concluded that multi-reference direct-CI calculations (MRDCI) using CASSCF MOs and/or natural orbitals (NOs) from a smaller CISD calculation, gave results close to full CI. The computed dissociation energies, D e , for the ground and first excited state of He 2 + were 2.4670 (2.4659) eV and 17.2 (17.1) cm -1 , respectively, at the highest level [without and with CP correction for basis-set superposition errors (BSSE)] of calculation with an [11s8p3d1f] GTO contraction, in reasonably good agreement with previous calculations, and estimated correct values, where available. It is believed that the computed D e , and the energy surface for the first excited state should be reasonably accurate. However, for the ground state, the effects of multiple f functions and/or functions of higher angular momentum have not been investigated owing to limitation of the available computing resources. This is probably the only weakness is the present study. (Author)

  20. Changes in the surface electronic states of semiconductor fine particles induced by high energy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Yamaki, Tetsuya; Asai, Keisuke; Ishigure, Kenkichi [Tokyo Univ. (Japan); Shibata, Hiromi

    1997-03-01

    The changes in the surface electronic states of Q-sized semiconductor particles in Langmuir-Blodgett (LB) films, induced by high energy ion irradiation, were examined by observation of ion induced emission and photoluminescence (PL). Various emission bands attributed to different defect sites in the band gap were observed at the initial irradiation stage. As the dose increased, the emissions via the trapping sites decreased in intensity while the band-edge emission developed. This suggests that the ion irradiation would remove almost all the trapping sites in the band gap. The low energy emissions, which show a multiexponential decay, were due to a donor-acceptor recombination between the deeply trapped carriers. It was found that the processes of formation, reaction, and stabilization of the trapping sites would predominantly occur under the photooxidizing conditions. (author)

  1. Bending of marble with intrinsic length scales: a gradient theory with surface energy and size effects

    International Nuclear Information System (INIS)

    Vardoulakis, I.; Kourkoulis, S.K.; Exadaktylos, G.

    1998-01-01

    A gradient bending theory is developed based on a strain energy function that includes the classical Bernoulli-Euler term, the shape correction term (microstructural length scale) introduced by Timoshenko, and a term associated with surface energy (micromaterial length scale) accounting for the bending moment gradient effect. It is shown that the last term is capable to interpret the size effect in three-point bending (3PB), namely the decrease of the failure load with decreasing beam length for the same aspect ratio. This theory is used to describe the mechanical behaviour of Dionysos-Pentelikon marble in 3PB. Series of tests with prismatic marble beams of the same aperture but with different lengths were conducted and it was concluded that the present theory predicts well the size effect. (orig.)

  2. A transitioning Arctic surface energy budget: the impacts of solar zenith angle, surface albedo and cloud radiative forcing

    Energy Technology Data Exchange (ETDEWEB)

    Sedlar, Joseph; Tjernstroem, Michael; Leck, Caroline [Stockholm University, Department of Meteorology, Stockholm (Sweden); Mauritsen, Thorsten [Max-Planck-Institute for Meteorology, Hamburg (Germany); Shupe, Matthew D.; Persson, P.O.G. [University of Colorado, NOAA-ESRL-PSD, Boulder, CO (United States); Brooks, Ian M.; Birch, Cathryn E. [University of Leeds, School of Earth and Environment, Leeds (United Kingdom); Sirevaag, Anders [University of Bergen, Bjerknes Center for Climate Research, Bergen (Norway); Nicolaus, Marcel [Norwegian Polar Institute, Tromsoe (Norway); Alfred Wegener Institute for Polar and Marine Research, Bremerhaven (Germany)

    2011-10-15

    Snow surface and sea-ice energy budgets were measured near 87.5 N during the Arctic Summer Cloud Ocean Study (ASCOS), from August to early September 2008. Surface temperature indicated four distinct temperature regimes, characterized by varying cloud, thermodynamic and solar properties. An initial warm, melt-season regime was interrupted by a 3-day cold regime where temperatures dropped from near zero to -7 C. Subsequently mean energy budget residuals remained small and near zero for 1 week until once again temperatures dropped rapidly and the energy budget residuals became negative. Energy budget transitions were dominated by the net radiative fluxes, largely controlled by the cloudiness. Variable heat, moisture and cloud distributions were associated with changing air-masses. Surface cloud radiative forcing, the net radiative effect of clouds on the surface relative to clear skies, is estimated. Shortwave cloud forcing ranged between -50 W m{sup -2} and zero and varied significantly with surface albedo, solar zenith angle and cloud liquid water. Longwave cloud forcing was larger and generally ranged between 65 and 85 W m{sup -2}, except when the cloud fraction was tenuous or contained little liquid water; thus the net effect of the clouds was to warm the surface. Both cold periods occurred under tenuous, or altogether absent, low-level clouds containing little liquid water, effectively reducing the cloud greenhouse effect. Freeze-up progression was enhanced by a combination of increasing solar zenith angles and surface albedo, while inhibited by a large, positive surface cloud forcing until a new air-mass with considerably less cloudiness advected over the experiment area. (orig.)

  3. 4H-SiC surface energy tuning by nitrogen up-take

    Energy Technology Data Exchange (ETDEWEB)

    Pitthan, E., E-mail: eduardo.pitthan@ufrgs.br [Institute for Advanced Materials, Devices and Nanotechnology, Rutgers University, Piscataway, NJ 08854 (United States); PGMICRO, UFRGS, 91509-900, Porto Alegre, RS (Brazil); Amarasinghe, V.P. [Institute for Advanced Materials, Devices and Nanotechnology, Rutgers University, Piscataway, NJ 08854 (United States); Xu, C.; Gustafsson, T. [Institute for Advanced Materials, Devices and Nanotechnology, Rutgers University, Piscataway, NJ 08854 (United States); Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States); Stedile, F.C. [PGMICRO, UFRGS, 91509-900, Porto Alegre, RS (Brazil); Instituto de Química, UFRGS, 91509-900, Porto Alegre, RS (Brazil); Feldman, L.C. [Institute for Advanced Materials, Devices and Nanotechnology, Rutgers University, Piscataway, NJ 08854 (United States); Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States)

    2017-04-30

    Highlights: • Wettability modification of 4H-SiC as a function of nitrogen adsorption is reported. • SiC surface energy was significantly reduced as nitrogen was incorporated. • Modifications obtained were proved to be inert to etching and stable against time. • Variable control of SiC surface provides new opportunities for biomedical applications. - Abstract: Surface energy modification and surface wettability of 4H silicon carbide (0001) as a function of nitrogen adsorption is reported. The surface wettability is shown to go from primarily hydrophilic to hydrophobic and the surface energy was significantly reduced with increasing nitrogen incorporation. These changes are investigated by x-ray photoelectron spectroscopy and contact angle measurements. The surface energy was quantitatively determined by the Fowkes model and interpreted primarily in terms of the variation of the surface chemistry with nitrogen coverage. Variable control of SiC surface energies with a simple and controllable atomic additive such as nitrogen that is inert to etching, stable against time, and also effective in electrical passivation, can provide new opportunities for SiC biomedical applications, where surface wetting plays an important role in the interaction with the biological interfaces.

  4. The Impact of Energy Consumption on the Surface Urban Heat Island in China’s 32 Major Cities

    Directory of Open Access Journals (Sweden)

    Weilin Liao

    2017-03-01

    Full Text Available Supported by the rapid economic development in the last few decades, China has become the largest energy consumer in the world. Alongside this, the effect of the anthropogenic heat released from energy consumption is increasingly apparent. We quantified the daytime and nighttime surface urban heat island intensity (SUHII for the 32 major cities in mainland China, using MODIS land surface temperature data from 2008 to 2012, and estimated the energy consumption intensity (ECI based on the correlation between energy consumption and the sum of nighttime lights. On this basis, the impact of energy consumption on the surface urban heat island in China’s 32 major cities was analyzed, by directly examining the relationship between SUHII and the urban-suburban difference in ECI. The results show that energy consumption has a significantly positive correlation with the nighttime SUHII, but no correlation with the daytime SUHII. It indicates that the cities with a larger urban-suburban difference in ECI have a far greater impact on SUHII during the nighttime. Therefore, the statistical analysis of the historical observation data in this study provides evidence for a long-held hypothesis that the anthropogenic heat released from energy consumption is an important contributor to the urban thermal environment.

  5. Molecular beam studies of energy transfer in scattering from crystal surfaces

    International Nuclear Information System (INIS)

    Guthrie, W.L.

    1983-01-01

    The translational energy distributions and angular distributions of D 2 O produced from the reaction of incident D 2 and O 2 on a (111) platinum single crystal surface have been measured through the use of a molecular beam-surface scattering apparatus equipped with a time-of-flight spectrometer. The translation energies were measured over the surface temperature range T/sub s/ = 664 K - 913 K and at scattering angles of 7 0 and 40 0 from the surface normal. The D 2 O translational energy, , was found to be approximately half the equilibrium value over the temperature range examined, with /2k varying from 280 K to 480 K. These results are discussed in terms of a non-equilibrium desorption model. The two-photon ionization spectrometer was built to investigate the internal rotational and vibrational energy distributions of NO scattered from Pt(111) surfaces. The rotational energy distributions were measured over the crystal temperature range of T/sub s/ = 400 K - 1200 K. The translational energy distributions and angular distributions were measured using the time-of-flight spectrometer over the crystal temperature range of 400 K - 110 K and for beam translational energies of 0.046 eV, 0.11 eV and 0.24 eV, so that complete energy exchange information for translation, rotation and vibration is available for this gas-surface system. Significant energy transfer was observed in all three modes

  6. Exploration, Sampling, And Reconstruction of Free Energy Surfaces with Gaussian Process Regression.

    Science.gov (United States)

    Mones, Letif; Bernstein, Noam; Csányi, Gábor

    2016-10-11

    Practical free energy reconstruction algorithms involve three separate tasks: biasing, measuring some observable, and finally reconstructing the free energy surface from those measurements. In more than one dimension, adaptive schemes make it possible to explore only relatively low lying regions of the landscape by progressively building up the bias toward the negative of the free energy surface so that free energy barriers are eliminated. Most schemes use the final bias as their best estimate of the free energy surface. We show that large gains in computational efficiency, as measured by the reduction of time to solution, can be obtained by separating the bias used for dynamics from the final free energy reconstruction itself. We find that biasing with metadynamics, measuring a free energy gradient estimator, and reconstructing using Gaussian process regression can give an order of magnitude reduction in computational cost.

  7. Effects of Surface Nonuniformities on the Mean Transverse Energy from Photocathodes

    Science.gov (United States)

    Karkare, Siddharth; Bazarov, Ivan

    2015-08-01

    The performance of photoinjectors is limited by the lowest value of the mean transverse energy of the electrons obtained from photocathodes. The factors that influence the mean transverse energy are poorly understood. In this paper, we develop models to calculate the effect of spatial work-function variations and subnanometer-scale roughness and surface defects on the mean transverse energy. We show that these can limit the lowest value of mean transverse energy achieved and that atomically perfect surfaces will be required to further reduce the mean transverse energy obtained from photocathodes.

  8. The health cost of energy. The health impacts of the different energy sources

    International Nuclear Information System (INIS)

    Masse, Roland

    2017-01-01

    This publication proposes an assessment of impacts of the different energy sources on public health. After a discussion of general aspects regarding this issue, the author addresses the identification and assessment of risks. While referring to different statistical data, he discusses the impacts of accidents in terms of dead, injured or evacuated people. He also addresses health impacts during a normal operation of power plants, i.e. in the case of nuclear plants (issue of exposure to various levels of radiation at the different steps of fuel cycle), of carbon-based plants (health risks and impacts during coal extraction, due to CO 2 emissions and to other toxic emissions, due to atmospheric pollution, identified risks, modelling attempts, assessment of a loss in life expectancy), and of other energies. While acknowledging that there are still many unknowns to assess these health impacts, the author compares these assessments. A summarized version of this article is proposed, in which the author briefly comments data regarding severe accidents related to energy production, discusses health consequences of electric power production and use, and makes a distinction between the most and less hazardous energies as far as public health is concerned

  9. Surface characterization by energy distribution measurements of secondary electrons and of ion-induced electrons

    International Nuclear Information System (INIS)

    Bauer, H.E.; Seiler, H.

    1988-01-01

    Instruments for surface microanalysis (e.g. scanning electron or ion microprobes, emission electron or ion microscopes) use the current of emitted secondary electrons or of emitted ion-induced electrons for imaging of the analysed surface. These currents, integrating over all energies of the emitted low energy electrons, are however, not well suited to surface analytical purposes. On the contrary, the energy distribution of these electrons is extremely surface-sensitive with respect to shape, size, width, most probable energy, and cut-off energy. The energy distribution measurements were performed with a cylindrical mirror analyser and converted into N(E), if necessary. Presented are energy spectra of electrons released by electrons and argon ions of some contaminated and sputter cleaned metals, the change of the secondary electron energy distribution from oxidized aluminium to clean aluminium, and the change of the cut-off energy due to work function change of oxidized aluminium, and of a silver layer on a platinum sample. The energy distribution of the secondary electrons often shows detailed structures, probably due to low-energy Auger electrons, and is broader than the energy distribution of ion-induced electrons of the same object point. (author)

  10. Characterization of Polymer Surfaces by the Use of Different Wetting Theories Regarding Acid-Base Properties

    Directory of Open Access Journals (Sweden)

    Eduard Kraus

    2017-01-01

    Full Text Available The existing wetting methods for the determination of acid-base properties on solid surfaces are discussed. Striving for a better understanding of the adhesive polymer interactions in adhesively joined polymers, the methods of Berger and van Oss-Chaudhury-Good were found as the most suitable methods for the investigation of wetting on solid polymer surfaces. Methods of nonlinear systems by Della Volpe and Siboni were adapted and evaluated on plastic surfaces. In the context of these investigations various data of the surface free energy as well as its components have been identified for a number of polymer surfaces by application of spatial equation solutions.

  11. Microclimatic models. Estimation of components of the energy balance over land surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Heikinheimo, M.; Venaelaeinen, A.; Tourula, T. [Finnish Meteorological Inst., Helsinki (Finland). Air Quality Dept.

    1996-12-31

    Climates at regional scale are strongly dependent on the interaction between atmosphere and its lower boundary, the oceans and the land surface mosaic. Land surfaces influence climate through their albedo, and the aerodynamic roughness, the processes of the biosphere and many soil hydrological properties; all these factors vary considerably geographically. Land surfaces receive a certain portion of the solar irradiance depending on the cloudiness, atmospheric transparency and surface albedo. Short-wave solar irradiance is the source of the heat energy exchange at the earth`s surface and also regulates many biological processes, e.g. photosynthesis. Methods for estimating solar irradiance, atmospheric transparency and surface albedo were reviewed during the course of this project. The solar energy at earth`s surface is consumed for heating the soil and the lower atmosphere. Where moisture is available, evaporation is one of the key components of the surface energy balance, because the conversion of liquid water into water vapour consumes heat. The evaporation process was studied by carrying out field experiments and testing parameterisation for a cultivated agricultural surface and for lakes. The micrometeorological study over lakes was carried out as part of the international `Northern Hemisphere Climatic Processes Experiment` (NOPEX/BAHC) in Sweden. These studies have been aimed at a better understanding of the energy exchange processes of the earth`s surface-atmosphere boundary for a more accurate and realistic parameterisation of the land surface in atmospheric models

  12. Microclimatic models. Estimation of components of the energy balance over land surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Heikinheimo, M; Venaelaeinen, A; Tourula, T [Finnish Meteorological Inst., Helsinki (Finland). Air Quality Dept.

    1997-12-31

    Climates at regional scale are strongly dependent on the interaction between atmosphere and its lower boundary, the oceans and the land surface mosaic. Land surfaces influence climate through their albedo, and the aerodynamic roughness, the processes of the biosphere and many soil hydrological properties; all these factors vary considerably geographically. Land surfaces receive a certain portion of the solar irradiance depending on the cloudiness, atmospheric transparency and surface albedo. Short-wave solar irradiance is the source of the heat energy exchange at the earth`s surface and also regulates many biological processes, e.g. photosynthesis. Methods for estimating solar irradiance, atmospheric transparency and surface albedo were reviewed during the course of this project. The solar energy at earth`s surface is consumed for heating the soil and the lower atmosphere. Where moisture is available, evaporation is one of the key components of the surface energy balance, because the conversion of liquid water into water vapour consumes heat. The evaporation process was studied by carrying out field experiments and testing parameterisation for a cultivated agricultural surface and for lakes. The micrometeorological study over lakes was carried out as part of the international `Northern Hemisphere Climatic Processes Experiment` (NOPEX/BAHC) in Sweden. These studies have been aimed at a better understanding of the energy exchange processes of the earth`s surface-atmosphere boundary for a more accurate and realistic parameterisation of the land surface in atmospheric models

  13. Surface energy balance in the ablation zone of Langfjordjøkelen, an arctic, maritime glacier in northern Norway

    NARCIS (Netherlands)

    Giesen, Rianne H.; Andreassen, Liss M.; Oerlemans, Johannes; van den Broeke, Michiel R.

    2014-01-01

    Glaciers in northern and southern Norway are subject to different daily and seasonal cycles of incoming solar radiation, which is presumably reflected in the importance of net solar radiation in their surface energy balance. We present a 3 year continuous record from an automatic weather station in

  14. Radiation exchange between persons and surfaces for building energy simulations

    DEFF Research Database (Denmark)

    Vorre, Mette Havgaard; Jensen, Rasmus Lund; Dreau, Jerome Le

    2015-01-01

    Thermal radiation within buildings is a significant component of thermal comfort. Typically the methods applied for calculating view factors between a person and its building surfaces requires great computational time. This research developed a view factor calculation method suitable for building...

  15. Earthquake Energy Distribution along the Earth Surface and Radius

    International Nuclear Information System (INIS)

    Varga, P.; Krumm, F.; Riguzzi, F.; Doglioni, C.; Suele, B.; Wang, K.; Panza, G.F.

    2010-07-01

    The global earthquake catalog of seismic events with M W ≥ 7.0, for the time interval from 1950 to 2007, shows that the depth distribution of earthquake energy release is not uniform. The 90% of the total earthquake energy budget is dissipated in the first ∼30km, whereas most of the residual budget is radiated at the lower boundary of the transition zone (410 km - 660 km), above the upper-lower mantle boundary. The upper border of the transition zone at around 410 km of depth is not marked by significant seismic energy release. This points for a non-dominant role of the slabs in the energy budged of plate tectonics. Earthquake number and energy release, although not well correlated, when analysed with respect to the latitude, show a decrease toward the polar areas. Moreover, the radiated energy has the highest peak close to (±5 o ) the so-called tectonic equator defined by Crespi et al. (2007), which is inclined about 30 o with respect to the geographic equator. At the same time the presence of a clear axial co- ordination of the radiated seismic energy is demonstrated with maxima at latitudes close to critical (±45 o ). This speaks about the presence of external forces that influence seismicity and it is consistent with the fact that Gutenberg-Richter law is linear, for events with M>5, only when the whole Earth's seismicity is considered. These data are consistent with an astronomical control on plate tectonics, i.e., the despinning (slowing of the Earth's angular rotation) of the Earth's rotation caused primarily by the tidal friction due to the Moon. The mutual position of the shallow and ∼660 km deep earthquake energy sources along subduction zones allows us to conclude that they are connected with the same slab along the W-directed subduction zones, but they may rather be disconnected along the opposed E-NE-directed slabs, being the deep seismicity controlled by other mechanisms. (author)

  16. Theoretical aspects of studies of oxide and semiconductor surfaces using low energy positrons

    Science.gov (United States)

    Fazleev, N. G.; Maddox, W. B.; Weiss, A. H.

    2011-01-01

    This paper presents the results of a theoretical study of positron surface and bulk states and annihilation characteristics of surface trapped positrons at the oxidized Cu(100) single crystal and at both As- and Ga-rich reconstructed GaAs(100) surfaces. The variations in atomic structure and chemical composition of the topmost layers of the surfaces associated with oxidation and reconstructions and the charge redistribution at the surfaces are found to affect localization and spatial extent of the positron surface-state wave functions. The computed positron binding energy, work function, and annihilation characteristics reveal their sensitivity to charge transfer effects, atomic structure and chemical composition of the topmost layers of the surfaces. Theoretical positron annihilation probabilities with relevant core electrons computed for the oxidized Cu(100) surface and the As- and Ga-rich reconstructed GaAs(100) surfaces are compared with experimental ones estimated from the positron annihilation induced Auger peak intensities measured from these surfaces.

  17. Nonstochastic effects of different energy beta emitters on pig skin

    International Nuclear Information System (INIS)

    Peel, D.M.; Hopewell, J.W.; Wells, J.; Charles, M.W.

    1984-01-01

    Circular areas of pig skin from 1- to 40-mm diameter were irradiated with β emitters of high, medium, and low energies, 90 Sr, 170 Tm, and 147 Pm, respectively. The study provides information for radiological protection problems of localized skin exposures. During the first 16 weeks after irradiation 90 Sr produced a first reaction due to epithelial cell death followed by a second reaction attributable to damage to the dermal blood vessels. 170 Tm and 147 Pm produced the epithelial reaction only. The epithelial dose response varied as a function of β energy. The doses required to produce moist desquamation in 50% of 15- to 22.5-mm fields (ED 50 ) were 30-45 Gy from 90 Sr, approx.80 Gy from 170 Tm, and approx.500 Gy from 147 Pm. An area effect was observed in the epithelial response to 90 Sr irradiation. The ED 50 for moist desquamation ranged from approx.25 Gy for a 40-mm source to approx.450 Gy for a 1-mm source. It is also suggested that the area effects could be explained by different modes of epithelial repopulation after irradiation

  18. Nanoscale control of energy and matter in plasma-surface interactions: Toward energy- and matter-efficient nanotech

    International Nuclear Information System (INIS)

    Ostrikov, K.

    2011-01-01

    The approach to control the elementary processes of plasma-surface interactions to direct the fluxes of energy and matter at nano- and subnanometer scales is introduced. This ability is related to the solution of the grand challenge of directing energy and matter at nanoscales and is critical for the renewable energy and energy-efficient technologies for a sustainable future development. The examples of deterministic synthesis of self-organized arrays of metastable nanostructures in the size range beyond the reach of the present-day nanofabrication are considered to illustrate this possibility. By using precisely controlled and kinetically fast nanoscale transfer of energy and matter under nonequilibrium conditions and harnessing numerous plasma-specific controls of species creation, delivery to the surface, nucleation, and large-scale self-organization of nuclei and nanostructures, the arrays of metastable nanostructures can be created, arranged, stabilized, and further processed to meet the specific requirements of the envisaged applications.

  19. Regional difference of the vertical structure of seasonal thermocline and its impact on sea surface temperature in the North Pacific

    Science.gov (United States)

    Yamaguchi, R.; Suga, T.

    2016-12-01

    Recent observational studies show that, during the warming season, a large amount of heat flux is penetrated through the base of thin mixed layer by vertical eddy diffusion, in addition to penetration of solar radiation [1]. In order to understand this heat penetration process due to vertical eddy diffusivity and its contribution to seasonal variation of sea surface temperature, we investigated the evolution of thermal stratification below the summertime thin mixed layer (i.e. evolution of seasonal thermocline) and its vertical structure in the North Pacific using high vertical resolution temperature profile observed by Argo floats. We quantified the vertical structure of seasonal thermocline as deviations from the linear structure where the vertical gradient of temperature is constant, that is, "shape anomaly". The shape anomaly is variable representing the extent of the bend of temperature profiles. We found that there are larger values of shape anomaly in the region where the seasonal sea surface temperature warming is relatively faster. To understand the regional difference of shape anomalies, we investigated the relationship between time changes in shape anomalies and net surface heat flux and surface kinetic energy flux. From May to July, the analysis indicated that, in a large part of North Pacific, there's a tendency for shape anomalies to develop strongly (weakly) under the conditions of large (small) downward net surface heat flux and small (large) downward surface kinetic energy flux. Since weak (strong) development of shape anomalies means efficient (inefficient) downward heat transport from the surface, these results suggest that the regional difference of the downward heat penetration below mixed layer is explained reasonably well by differences in surface heat forcing and surface wind forcing in a vertical one dimensional framework. [1] Hosoda et al. (2015), J. Oceanogr., 71, 541-556.

  20. Reconnoitering the effect of shallow groundwater on land surface temperature and surface energy balance using MODIS and SEBS

    Directory of Open Access Journals (Sweden)

    F. Alkhaier

    2012-07-01

    Full Text Available The possibility of observing shallow groundwater depth and areal extent using satellite measurements can support groundwater models and vast irrigation systems management. Moreover, these measurements can help to include the effect of shallow groundwater on surface energy balance within land surface models and climate studies, which broadens the methods that yield more reliable and informative results. To examine the capacity of MODIS in detecting the effect of shallow groundwater on land surface temperature and the surface energy balance in an area within Al-Balikh River basin in northern Syria, we studied the interrelationship between in-situ measured water table depths and land surface temperatures measured by MODIS. We, also, used the Surface Energy Balance System (SEBS to calculate surface energy fluxes, evaporative fraction and daily evaporation, and inspected their relationships with water table depths. We found out that the daytime temperature increased while the nighttime temperature decreased when the depth of the water table increased. And, when the water table depth increased, net radiation, latent and ground heat fluxes, evaporative fraction and daily evaporation decreased, while sensible heat flux increased. This concords with the findings of a companion paper (Alkhaier et al., 2012. The observed clear relationships were the result of meeting both conditions that were concluded in the companion paper, i.e. high potential evaporation and big contrast in day-night temperature. Moreover, the prevailing conditions in this study area helped SEBS to yield accurate estimates. Under bare soil conditions and under the prevailing weather conditions, we conclude that MODIS is suitable for detecting the effect of shallow groundwater because it has proper imaging times and adequate sensor accuracy; nevertheless, its coarse spatial resolution is disadvantageous.

  1. Homogeneous near surface activity distribution by double energy activation for TLA

    International Nuclear Information System (INIS)

    Takacs, S.; Ditroi, F.; Tarkanyi, F.

    2007-01-01

    Thin layer activation (TLA) is a versatile tool for activating thin surface layers in order to study real-time the surface loss by wear, corrosion or erosion processes of the activated parts, without disassembling or stopping running mechanical structures or equipment. The research problem is the determination of the irradiation parameters to produce point-like or large area optimal activity-depth distribution in the sample. Different activity-depth profiles can be produced depending on the type of the investigated material and the nuclear reaction used. To produce activity that is independent of the depth up to a certain depth is desirable when the material removed from the surface by wear, corrosion or erosion can be collected completely. By applying dual energy irradiation the thickness of this quasi-constant activity layer can be increased or the deviation of the activity distribution from a constant value can be minimized. In the main, parts made of metals and alloys are suitable for direct activation, but by using secondary particle implantation the wear of other materials can also be studied in a surface range a few micrometers thick. In most practical cases activation of a point-like spot (several mm 2 ) is enough to monitor the wear, corrosion or erosion, but for special problems relatively large surfaces areas of complicated spatial geometry need to be activated uniformly. Two ways are available for fulfilling this task, (1) production of large area beam spot or scanning the beam over the surface in question from the accelerator side, or (2) a programmed 3D movement of the sample from the target side. Taking into account the large variability of tasks occurring in practice, the latter method was chosen as the routine solution in our cyclotron laboratory

  2. Targeting for energy efficiency and improved energy collaboration between different companies using total site analysis (TSA)

    International Nuclear Information System (INIS)

    Hackl, Roman; Andersson, Eva; Harvey, Simon

    2011-01-01

    Rising fuel prices, increasing costs associated with emissions of green house gases and the threat of global warming make efficient use of energy more and more important. Industrial clusters have the potential to significantly increase energy efficiency by energy collaboration. In this paper Sweden's largest chemical cluster is analysed using the total site analysis (TSA) method. TSA delivers targets for the amount of utility consumed and generated through excess energy recovery by the different processes. The method enables investigation of opportunities to deliver waste heat from one process to another using a common utility system. The cluster consists of 5 chemical companies producing a variety of products, including polyethylene (PE), polyvinyl chloride (PVC), amines, ethylene, oxygen/nitrogen and plasticisers. The companies already work together by exchanging material streams. In this study the potential for energy collaboration is analysed in order to reach an industrial symbiosis. The overall heating and cooling demands of the site are around 442 MW and 953 MW, respectively. 122 MW of heat is produced in boilers and delivered to the processes. TSA is used to stepwise design a site-wide utility system which improves energy efficiency. It is shown that heat recovery in the cluster can be increased by 129 MW, i.e. the current utility demand could be completely eliminated and further 7 MW excess steam can be made available. The proposed retrofitted utility system involves the introduction of a site-wide hot water circuit, increased recovery of low pressure steam and shifting of heating steam pressure to lower levels in a number heat exchangers when possible. Qualitative evaluation of the suggested measures shows that 60 MW of the savings potential could to be achieved with moderate changes to the process utility system corresponding to 50% of the heat produced from purchased fuel in the boilers of the cluster. Further analysis showed that after implementation

  3. Ignition in net for different energy confinement time scalings

    International Nuclear Information System (INIS)

    Johner, J.; Prevot, F.

    1988-06-01

    A zero-dimensional profile dependent model is used to assess the feasibility of ignition in the extended version of NET. Five recent scalings for the energy confinement time (Goldston, Kaye All, Kaye Big, Shimomura-Odajima, Rebut-Lallia) are compared in the frame of two different scenarii, i.e., H-mode with a flat density profile or L-mode with a peaked density profile. For the flat density H-mode case, ignition is accessible with none of the scalings except Rebut-Lallia's. For the peaked density L-mode case, ignition is accessible with none of the scalings except Rebut-Lallia's. For the two Kaye's scalings, ignition is forbidden in H-mode even with the peaked density profile. For the Rebut-Lallia scaling, ignition is allowed in L-mode even with the flat density profile

  4. Band energy control of molybdenum oxide by surface hydration

    Energy Technology Data Exchange (ETDEWEB)

    Butler, Keith T., E-mail: k.t.butler@bath.ac.uk; Walsh, Aron [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Crespo-Otero, Rachel [School of Biological and Chemical Sciences, Queen Mary University London, Mile End Road, London E1 4NS (United Kingdom); Buckeridge, John; Scanlon, David O. [University College London, Kathleen Lonsdale Materials Chemistry, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Bovill, Edward; Lidzey, David [Department of Physics and Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

    2015-12-07

    The application of oxide buffer layers for improved carrier extraction is ubiquitous in organic electronics. However, the performance is highly susceptible to processing conditions. Notably, the interface stability and electronic structure is extremely sensitive to the uptake of ambient water. In this study we use density functional theory calculations to asses the effects of adsorbed water on the electronic structure of MoO{sub x}, in the context of polymer-fullerene solar cells based on PCDTBT. We obtain excellent agreement with experimental values of the ionization potential for pristine MoO{sub 3} (010). We find that IP and EA values can vary by as much as 2.5 eV depending on the oxidation state of the surface and that adsorbed water can either increase or decrease the IP and EA depending on the concentration of surface water.

  5. Optical emission from low-energy ion-surface collisions

    International Nuclear Information System (INIS)

    White, C.W.; Thomas, E.W.; Van der Weg, W.F.; Tolk, N.H.

    1977-01-01

    Impact of energetic heavy particles on surfaces gives rise to emission of optical radiation from reflected particles, sputtered particles and also from excited states of the solid. The present status of research in this area is reviewed with emphasis on understanding the basic mechanisms which give rise to formation of excited states. The spectral line shape from ejected atoms may be analyzed to provide information on the distribution of speeds and directions of the excited species; the line intensity provides a measure of the probability for creating the state. Formation of excited species is related both to the collision processes within the solid and also to the interaction of the recoiling ejected species with the target surface. Most ejected species are atomic but important examples of ejected molecules are also discussed. Luminescence induced in the solid itself is related to recombination of electron hole pairs and is related significantly to the presence of defects

  6. Bending energy penalty enhances the adhesive strength of functional amyloid curli to surfaces

    Science.gov (United States)

    Zhang, Yao; Wang, Ao; DeBenedictis, Elizabeth P.; Keten, Sinan

    2017-11-01

    The functional amyloid curli fiber, a major proteinaceous component of biofilm extracellular matrices, plays an important role in biofilm formation and enterobacteriaceae adhesion. Curli nanofibers exhibit exceptional underwater adhesion to various surfaces, have high rigidity and strong tensile mechanical properties, and thus hold great promise in biomaterials. The mechanisms of how curli fibers strongly attach to surfaces and detach under force remain elusive. To investigate curli fiber adhesion to surfaces, we developed a coarse-grained curli fiber model, in which the protein subunit CsgA (curli specific gene A) self-assembles into the fiber. The coarse-grained model yields physiologically relevant and tunable bending rigidity and persistence length. The force-induced desorption of a single curli fiber is examined using coarse-grained modeling and theoretical analysis. We find that the bending energy penalty arising from high persistence length enhances the resistance of the curli fiber against desorption and thus strengthens the adhesion of the curli fiber to surfaces. The CsgA-surface adhesion energy and the curli fiber bending rigidity both play crucial roles in the resistance of curli fiber against desorption from surfaces. To enable the desorption process, the applied peeling force must overcome both the interfacial adhesion energy and the energy barrier for bending the curli fiber at the peeling front. We show that the energy barrier to desorption increases with the interfacial adhesion energy, however, the bending induced failure of a single curli fiber limits the work of adhesion if the proportion of the CsgA-surface adhesion energy to the CsgA-CsgA cohesive energy becomes large. These results illustrate that the optimal adhesion performance of nanofibers is dictated by the interplay between bending, surface energy and cohesive energy. Our model provides timely insight into enterobacteriaceae adhesion mechanisms as well as future designs of engineered

  7. Scaling Relations for Adsorption Energies on Doped Molybdenum Phosphide Surfaces

    International Nuclear Information System (INIS)

    Fields, Meredith; Tsai, Charlie; Chen, Leanne D.; Abild-Pedersen, Frank; Nørskov, Jens K.; Chan, Karen

    2017-01-01

    Molybdenum phosphide (MoP), a well-documented catalyst for applications ranging from hydrotreating reactions to electrochemical hydrogen evolution, has yet to be mapped from a more fundamental perspective, particularly in the context of transition-metal scaling relations. In this work, we use periodic density functional theory to extend linear scaling arguments to doped MoP surfaces and understand the behavior of the phosphorus active site. The derived linear relationships for hydrogenated C, N, and O species on a variety of doped surfaces suggest that phosphorus experiences a shift in preferred bond order depending on the degree of hydrogen substitution on the adsorbate molecule. This shift in phosphorus hybridization, dependent on the bond order of the adsorbate to the surface, can result in selective bond weakening or strengthening of chemically similar species. As a result, we discuss how this behavior deviates from transition-metal, sulfide, carbide, and nitride scaling relations, and we discuss potential applications in the context of electrochemical reduction reactions.

  8. Surface wettability and energy effects on the biological performance of poly-3-hydroxybutyrate films treated with RF plasma

    Energy Technology Data Exchange (ETDEWEB)

    Syromotina, D.S. [Department of Experimental Physics, National Research Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); Surmenev, R.A., E-mail: rsurmenev@gmail.com [Department of Experimental Physics, National Research Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, 70569 Stuttgart (Germany); Surmeneva, M.A. [Department of Experimental Physics, National Research Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); Boyandin, A.N.; Nikolaeva, E.D. [Institute of Biophysics of Siberian Branch of Russian Academy of Sciences, 50/50 Akademgorodok, Krasnoyarsk 660036 (Russian Federation); School of Fundamental Biology and Biotechnology, Siberian Federal University, 79 Svobodny pr., 660041 Krasnoyarsk (Russian Federation); Prymak, O.; Epple, M. [Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, 45117 Essen (Germany); Ulbricht, M. [Technical Chemistry II and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, 45141 Essen (Germany); Oehr, C. [Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB, 70569 Stuttgart (Germany); Volova, T.G. [Institute of Biophysics of Siberian Branch of Russian Academy of Sciences, 50/50 Akademgorodok, Krasnoyarsk 660036 (Russian Federation); School of Fundamental Biology and Biotechnology, Siberian Federal University, 79 Svobodny pr., 660041 Krasnoyarsk (Russian Federation)

    2016-05-01

    The surface properties of poly-3-hydroxybutyrate (P3HB) membranes were modified using oxygen and an ammonia radio-frequency (RF, 13.56 MHz) plasma. The plasma treatment procedures used in the study only affected the surface properties, including surface topography, without inducing any significant changes in the crystalline structure of the polymer, with the exception being a power level of 250 W. The wettability of the modified P3HB surfaces was significantly increased after the plasma treatment, irrespective of the treatment procedure used. It was revealed that both surface chemistry and surface roughness changes caused by the plasma treatment affected surface wettability. A treatment-induced surface aging effect was observed and resulted in an increase in the water contact angle and a decrease in the surface free energy. However, the difference in the water contact angle between the polymers that had been treated for 4 weeks and the untreated polymer surfaces was still significant. A dependence between cell adhesion and proliferation and the polar component of the surface energy was revealed. The increase in the polar component after the ammonia plasma modification significantly increased cell adhesion and proliferation on biodegradable polymer surfaces compared to the untreated P3HB and the P3HB modified using an oxygen plasma. - Highlights: • Plasma treatment affected the topography of poly(3-hydroxybutyrate) (P3HB). • Plasma treatment resulted in improvement of the surface wettability. • No alteration of the bulk properties of the polymers was observed. • The ammonia plasma treatment at 150 W improved the cell adhesion and proliferation.

  9. Apparent Surface Free Energy of Polymer/Paper Composite Material Treated by Air Plasma

    Directory of Open Access Journals (Sweden)

    Konrad Terpiłowski

    2017-01-01

    Full Text Available Surface plasma treatment consists in changes of surface properties without changing internal properties. In this paper composite polymer/paper material is used for production of packaging in cosmetic industry. There are problems with bonding this material at the time of packaging production due to its properties. Composite surface was treated by air plasma for 1, 10, 20, and 30 s. The advancing and receding contact angles of water, formamide, and diiodomethane were measured using both treated and untreated samples. Apparent surface free energy was estimated using the hysteresis (CAH and Van Oss, Good, Chaudhury approaches (LWAB. Surface roughness was investigated using optical profilometry and identification of after plasma treatment emerging chemical groups was made by means of the XPS (X-ray photoelectron spectroscopy technique. After plasma treatment the values of contact angles decreased which is particularly evident for polar liquids. Apparent surface free energy increased compared to that of untreated samples. Changes of energy value are due to the electron-donor parameter of energy. This parameter increases as a result of adding polar groups at the time of surface plasma activation. Changes of surface properties are combination of increase of polar chemical functional groups, increase on the surface, and surface roughness increase.

  10. In vitro characterization of two different atmospheric plasma jet chemical functionalizations of titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Mussano, F., E-mail: federico.mussano@unito.it [CIR Dental School, Department of Surgical Sciences UNITO, via Nizza 230, 10126, Turin (Italy); Genova, T. [CIR Dental School, Department of Surgical Sciences UNITO, via Nizza 230, 10126, Turin (Italy); Department of Life Sciences and Systems Biology, UNITO, via Accademia Albertina 13, 10123, Turin (Italy); Verga Falzacappa, E. [Department of Molecular Science and Nanosystems, UNIVE, Via Torino 155, 30170, Venezia (Italy); Nadir srl, Via Torino 155, 30170 Venezia (Italy); Scopece, P. [Nadir srl, Via Torino 155, 30170 Venezia (Italy); Munaron, L. [Department of Life Sciences and Systems Biology, UNITO, via Accademia Albertina 13, 10123, Turin (Italy); Centre for Nanostructured Interfaces and Surfaces (NIS) (Italy); Rivolo, P.; Mandracci, P. [Politecnico di Torino, Department of Applied Science and Technology, Materials and Microsoystems Laboratory (ChiLab), Corso Duca degli Abruzzi 24, 10129, Torino (Italy); Benedetti, A. [Department of Molecular Science and Nanosystems, UNIVE, Via Torino 155, 30170, Venezia (Italy); Carossa, S. [CIR Dental School, Department of Surgical Sciences UNITO, via Nizza 230, 10126, Turin (Italy); Patelli, A. [Department of Physics and Astronomy, UNIPD, via Marzolo 8, 35122 Padova (Italy)

    2017-07-01

    Highlights: • NH{sub 2}-Ti and COOH/R-Ti obtained via atmospheric plasma jet RF-APPJ portable equipment. • Higher quantity of adsorbed proteins and improved cell adhesion on treated surfaces. • More tapered and elongated cells on NH{sub 2}-Ti compared to COOH/R-Ti. • Higher osteocalcin expression on NH{sub 2}-Ti. - Abstract: Plasma surface activation and plasma polymers deposition are promising technologies capable to modulate biologically relevant surface features of biomaterials. The purpose of this study was to evaluate the biological effects of two different surface modifications, i.e. amine (NH{sub 2}-Ti) and carboxylic/esteric (COOH/R-Ti) functionalities obtained from 3-aminopropyltriethoxysilane (3-APTES) and methylmethacrylate (MMA) precursors, respectively, through an atmospheric plasma jet RF-APPJ portable equipment. The coatings were characterized by Scanning Electron Microscopy, FT-IR spectroscopy, XPS and surface energy calculations. Stability in water and after UV sterilization were also verified. The pre-osteoblastic murine cell line MC3T3-E1 was used to perform the in-vitro tests. The treated samples showed a higher quantity of adsorbed proteins and improved osteoblast cells adhesion on the surfaces compared to the pristine titanium, in particular the COOH/R-Ti led to a nearly two-fold improvement. Cell proliferation on coated samples was initially (at 24 h) lower than on titanium control, while, at 48 h, COOH/R-Ti reached the proliferation rate of pristine titanium. Cells grown on NH{sub 2}-Ti were more tapered and elongated in shape with lower areas than on COOH/R-Ti enriched surfaces. Finally, NH{sub 2}-Ti significantly enhanced osteocalcin production, starting from 14 days, while COOH/R-Ti had this effect only from 21 days. Notably, NH{sub 2}-Ti was more efficient than COOH/R-Ti at 21 days. The amine functionality elicited the most relevant osteogenic effect in terms of osteocalcin expression, thus establishing an interesting correlation

  11. CORROSION AND SURFACE PROTECTION IN MACHINE MATERIALS FRICTION HAVE DIFFERENT SURFACE PAIRS EXPERIMENTAL INVESTIGATION OF FACTORS

    Directory of Open Access Journals (Sweden)

    Senai YALCINKAYA

    2017-05-01

    Full Text Available Friction force, normal force, linear change. The normal force varies with the loads on the friction object. In order to determine the friction force and the friction coefficient, the friction object and the friction speed are used. The experimental work was carried out in three stages. In the first stage, the effect of normal force on the friction force was studied. In the second step, the friction force of the friction surface area is influenced. The effect of the change of the shear rate in step 3 on the friction force was investigated. At the last stage, the experimental study of the effect of the material selection on the friction force was made and it was seen that the aluminum / brass surface pair had the smallest friction coefficient as a result of the opening. The greatest coefficient of friction is found in the pair of glass / felt objects.

  12. Imaging a multidimensional multichannel potential energy surface: Photodetachment of H(-)(NH3) and NH4 (.).

    Science.gov (United States)

    Hu, Qichi; Song, Hongwei; Johnson, Christopher J; Li, Jun; Guo, Hua; Continetti, Robert E

    2016-06-28

    Probes of the Born-Oppenheimer potential energy surfaces governing polyatomic molecules often rely on spectroscopy for the bound regions or collision experiments in the continuum. A combined spectroscopic and half-collision approach to image nuclear dynamics in a multidimensional and multichannel system is reported here. The Rydberg radical NH4 and the double Rydberg anion NH4 (-) represent a polyatomic system for benchmarking electronic structure and nine-dimensional quantum dynamics calculations. Photodetachment of the H(-)(NH3) ion-dipole complex and the NH4 (-) DRA probes different regions on the neutral NH4 PES. Photoelectron energy and angular distributions at photon energies of 1.17, 1.60, and 2.33 eV compare well with quantum dynamics. Photoelectron-photofragment coincidence experiments indicate dissociation of the nascent NH4 Rydberg radical occurs to H + NH3 with a peak kinetic energy of 0.13 eV, showing the ground state of NH4 to be unstable, decaying by tunneling-induced dissociation on a time scale beyond the present scope of multidimensional quantum dynamics.

  13. Spatiotemporal variability in surface energy balance across tundra, snow and ice in Greenland

    DEFF Research Database (Denmark)

    Lund, Magnus; Stiegler, Christian; Abermann, Jakob

    2017-01-01

    The surface energy balance (SEB) is essential for understanding the coupled cryosphere–atmosphere system in the Arctic. In this study, we investigate the spatiotemporal variability in SEB across tundra, snow and ice. During the snow-free period, the main energy sink for ice sites is surface melt....... For tundra, energy is used for sensible and latent heat flux and soil heat flux leading to permafrost thaw. Longer snow-free period increases melting of the Greenland Ice Sheet and glaciers and may promote tundra permafrost thaw. During winter, clouds have a warming effect across surface types whereas during...

  14. Energy characteristics of finest coal particles surfaces versus their upgrading using flotation

    Energy Technology Data Exchange (ETDEWEB)

    Jerzy Sablik

    2007-07-01

    The paper presents selected results of investigations on energy properties of the fine coal particles, and methodological grounds for conducting such investigations. Using the discussed relationships, values of contact angle of coal particles with various degree of coalification in the range defined by the energy nonhomogeneity of the surfaces were computed. There have been determined the values of the contact angles of coal particles with hydrophobic and hydrophilic surfaces after coating with nonpolar and polar reagents. The energy state of the surfaces of coal particles in the feeds and products of industrial flotation were determined, which enabled to evaluate this process. 22 refs., 6 figs., 4 tabs.

  15. CORROSION AND SURFACE PROTECTION IN MACHINE MATERIALS FRICTION HAVE DIFFERENT SURFACE PAIRS EXPERIMENTAL INVESTIGATION OF FACTORS

    OpenAIRE

    Senai YALCINKAYA

    2017-01-01

    Friction force, normal force, linear change. The normal force varies with the loads on the friction object. In order to determine the friction force and the friction coefficient, the friction object and the friction speed are used. The experimental work was carried out in three stages. In the first stage, the effect of normal force on the friction force was studied. In the second step, the friction force of the friction surface area is influenced. The effect of the change of the s...

  16. An explanation for the different climate sensitivities of land and ocean surfaces based on the diurnal cycle

    Directory of Open Access Journals (Sweden)

    A. Kleidon

    2017-09-01

    Full Text Available Observations and climate model simulations consistently show a higher climate sensitivity of land surfaces compared to ocean surfaces. Here we show that this difference in temperature sensitivity can be explained by the different means by which the diurnal variation in solar radiation is buffered. While ocean surfaces buffer the diurnal variations by heat storage changes below the surface, land surfaces buffer it mostly by heat storage changes above the surface in the lower atmosphere that are reflected in the diurnal growth of a convective boundary layer. Storage changes below the surface allow the ocean surface–atmosphere system to maintain turbulent fluxes over day and night, while the land surface–atmosphere system maintains turbulent fluxes only during the daytime hours, when the surface is heated by absorption of solar radiation. This shorter duration of turbulent fluxes on land results in a greater sensitivity of the land surface–atmosphere system to changes in the greenhouse forcing because nighttime temperatures are shaped by radiative exchange only, which are more sensitive to changes in greenhouse forcing. We use a simple, analytic energy balance model of the surface–atmosphere system in which turbulent fluxes are constrained by the maximum power limit to estimate the effects of these different means to buffer the diurnal cycle on the resulting temperature sensitivities. The model predicts that land surfaces have a 50 % greater climate sensitivity than ocean surfaces, and that the nighttime temperatures on land increase about twice as much as daytime temperatures because of the absence of turbulent fluxes at night. Both predictions compare very well with observations and CMIP5 climate model simulations. Hence, the greater climate sensitivity of land surfaces can be explained by its buffering of diurnal variations in solar radiation in the lower atmosphere.

  17. Extraction of topographic and material contrasts on surfaces from SEM images obtained by energy filtering detection with low-energy primary electrons

    International Nuclear Information System (INIS)

    Nagoshi, Masayasu; Aoyama, Tomohiro; Sato, Kaoru

    2013-01-01

    Secondary electron microscope (SEM) images have been obtained for practical materials using low primary electron energies and an in-lens type annular detector with changing negative bias voltage supplied to a grid placed in front of the detector. The kinetic-energy distribution of the detected electrons was evaluated by the gradient of the bias-energy dependence of the brightness of the images. This is divided into mainly two parts at about 500 V, high and low brightness in the low- and high-energy regions, respectively and shows difference among the surface regions having different composition and topography. The combination of the negative grid bias and the pixel-by-pixel image subtraction provides the band-pass filtered images and extracts the material and topographic information of the specimen surfaces. -- Highlights: ► Scanning electron (SE) images contain many kind of information on material surfaces. ► We investigate energy-filtered SE images for practical materials. ► The brightness of the images is divided into two parts by the bias voltage. ► Topographic and material contrasts are extracted by subtracting the filtered images.

  18. Surface heterogeneity impacts on boundary layer dynamics via energy balance partitioning

    Science.gov (United States)

    The role of land-atmosphere interactions under heterogeneous surface conditions is investigated in order to identify mechanisms responsible for altering surface heat and moisture fluxes. Twelve coupled land surface – large eddy simulation scenarios with four different length scales of surface variab...

  19. Genetic adaptation of Streptococcus mutans during biofilm formation on different types of surfaces

    Directory of Open Access Journals (Sweden)

    Aharoni Reuven

    2010-02-01

    Full Text Available Abstract Background Adhesion and successful colonization of bacteria onto solid surfaces play a key role in biofilm formation. The initial adhesion and the colonization of bacteria may differ between the various types of surfaces found in oral cavity. Therefore, it is conceivable that diverse biofilms are developed on those various surfaces. The aim of the study was to investigate the molecular modifications occurring during in vitro biofilm development of Streptococcus mutans UA159 on several different dental surfaces. Results Growth analysis of the immobilized bacterial populations generated on the different surfaces shows that the bacteria constructed a more confluent and thick biofilms on a hydroxyapatite surface compared to the other tested surfaces. Using DNA-microarray technology we identified the differentially expressed genes of S. mutans, reflecting the physiological state of biofilms formed on the different biomaterials tested. Eight selected genes were further analyzed by real time RT-PCR. To further determine the impact of the tested material surfaces on the physiology of the bacteria, we tested the secretion of AI-2 signal by S. mutans embedded on those biofilms. Comparative transcriptome analyses indicated on changes in the S. mutans genome in biofilms formed onto different types of surfaces and enabled us to identify genes most differentially expressed on those surfaces. In addition, the levels of autoinducer-2 in biofilms from the various tested surfaces were different. Conclusions Our results demonstrate that gene expression of S. mutans differs in biofilms formed on tested surfaces, which manifest the physiological state of bacteria influenced by the type of surface material they accumulate onto. Moreover, the stressful circumstances of adjustment to the surface may persist in the bacteria enhancing intercellular signaling and surface dependent biofilm formation.

  20. Surface runoff and soil erosion by difference of surface cover characteristics using by an oscillating rainfall simulator

    Science.gov (United States)

    Kim, J. K.; Kim, M. S.; Yang, D. Y.

    2017-12-01

    Sediment transfer within hill slope can be changed by the hydrologic characteristics of surface material on hill slope. To better understand sediment transfer of the past and future related to climate changes, studies for the changes of soil erosion due to hydrological characteristics changes by surface materials on hill slope are needed. To do so, on-situ rainfall simulating test was conducted on three different surface conditions, i.e. well covered with litter layer condition (a), undisturbed bare condition (b), and disturbed bare condition (c) and these results from rainfall simulating test were compared with that estimated using the Limburg Soil Erosion Model (LISEM). The result from the rainfall simulating tests showed differences in the infiltration rate (a > b > c) and the highest soil erosion rate was occurred on c condition. The result from model also was similar to those from rainfall simulating tests, however, the difference from the value of soil erosion rate between two results was quite large on b and c conditions. These results implied that the difference of surface conditions could change the surface runoff and soil erosion and the result from the erosion model might significantly underestimate on bare surface conditions rather than that from rainfall simulating test.

  1. Intermolecular potential energy surface and thermophysical properties of ethylene oxide.

    Science.gov (United States)

    Crusius, Johann-Philipp; Hellmann, Robert; Hassel, Egon; Bich, Eckard

    2014-10-28

    A six-dimensional potential energy hypersurface (PES) for two interacting rigid ethylene oxide (C2H4O) molecules was determined from high-level quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the MP2 and CCSD(T) levels of theory was utilized to determine interaction energies for 10178 configurations of two molecules. An analytical site-site potential function with 19 sites per ethylene oxide molecule was fitted to the interaction energies and fine tuned to agree with data for the second acoustic virial coefficient from accurate speed of sound measurements. The PES was validated by computing the second virial coefficient, shear viscosity, and thermal conductivity. The values of these properties are substantiated by the best experimental data as they tend to fall within the uncertainty intervals and also obey the experimental temperature functions, except for viscosity, where experimental data are insufficient. Due to the lack of reliable data, especially for the transport properties, our calculated values are currently the most accurate estimates for these properties of ethylene oxide.

  2. The Modelling Analysis of the Response of Convective Transport of Energy and Water to Multiscale Surface Heterogeneity over Tibetan Plateau

    Science.gov (United States)

    SUN, G.; Hu, Z.; Ma, Y.; Ma, W.

    2017-12-01

    The land-atmospheric interactions over a heterogeneous surface is a tricky issue for accurately understanding the energy-water exchanges between land surface and atmosphere. We investigate the vertical transport of energy and water over a heterogeneous land surface in Tibetan Plateau during the evolution of the convective boundary layer using large eddy simulation (WRF_LES). The surface heterogeneity is created according to remote sensing images from high spatial resolution LandSat ETM+ images. The PBL characteristics over a heterogeneous surface are analyzed in terms of secondary circulations under different background wind conditions based on the horizontal and vertical distribution and evolution of wind. The characteristics of vertical transport of energy and heat over a heterogeneous surface are analyzed in terms of the horizontal distribution as well as temporal evolution of sensible and latent heat fluxes at different heights under different wind conditions on basis of the simulated results from WRF_LES. The characteristics of the heat and water transported into the free atmosphere from surface are also analyzed and quantified according to the simulated results from WRF_LES. The convective transport of energy and water are analyzed according to horizontal and vertical distributions of potential temperature and vapor under different background wind conditions. With the analysis based on the WRF_LES simulation, the performance of PBL schemes of mesoscale simulation (WRF_meso) is evaluated. The comparison between horizontal distribution of vertical fluxes and domain-averaged vertical fluxes of the energy and water in the free atmosphere is used to evaluate the performance of PBL schemes of WRF_meso in the simulation of vertical exchange of energy and water. This is an important variable because only the energy and water transported into free atmosphere is able to influence the regional and even global climate. This work would will be of great significance not

  3. Evaporation behaviour of different organic effluents from open surfaces.

    Science.gov (United States)

    Jhorar, B S; Malik, R S

    1993-01-01

    Production of large quantities of effluents from different industrial units and the problems of their disposal necessitated this evaporation study. The evaporation of water, sewage water, oil refinery effluent, papermill effluent and liquor distillery effluent was observed in glass beakers when placed (i) in an oven at 60 degrees C and (ii) in screen house for 30 days, by periodically weighing of the beakers. In other experiments, the effect of increasing the frequency of stirring on increasing the evaporation efficiency of the liquor distillery effluent (ELD) was examined in detail. All of the organic effluents except ELD had similar evaporation behaviours as water, but formation of a self-forming film caused the evaporation of ELD to be considerably lower. Resistance to evaporation caused by this film was found to be a decreasing function of the frequency of stirring. This study has a bearing on improving the efficiency of evaporation lagoons, and three stirrings in a day with a manually drawn stirrer in a full-scale lagoon are proposed as a practical and economically viable technique to save 44% of lagoon land in arid and semi-arid regions of the world.

  4. Statistical Equilibria of Turbulence on Surfaces of Different Symmetry

    Science.gov (United States)

    Qi, Wanming; Marston, Brad

    2012-02-01

    We test the validity of statistical descriptions of freely decaying 2D turbulence by performing direct numerical simulations (DNS) of the Euler equation with hyperviscosity on a square torus and on a sphere. DNS shows, at long times, a dipolar coherent structure in the vorticity field on the torus but a quadrapole on the sphereootnotetextJ. Y-K. Cho and L. Polvani, Phys. Fluids 8, 1531 (1996).. A truncated Miller-Robert-Sommeria theoryootnotetextA. J. Majda and X. Wang, Nonlinear Dynamics and Statistical Theories for Basic Geophysical Flows (Cambridge University Press, 2006). can explain the difference. The theory conserves up to the second-order Casimir, while also respecting conservation laws that reflect the symmetry of the domain. We further show that it is equivalent to the phenomenological minimum-enstrophy principle by generalizing the work by Naso et al.ootnotetextA. Naso, P. H. Chavanis, and B. Dubrulle, Eur. Phys. J. B 77, 284 (2010). to the sphere. To explain finer structures of the coherent states seen in DNS, especially the phenomenon of confinement, we investigate the perturbative inclusion of the higher Casimir constraints.

  5. Unravelling Diurnal Asymmetry of Surface Temperature in Different Climate Zones.

    Science.gov (United States)

    Vinnarasi, R; Dhanya, C T; Chakravorty, Aniket; AghaKouchak, Amir

    2017-08-04

    Understanding the evolution of Diurnal Temperature Range (DTR), which has contradicting global and regional trends, is crucial because it influences environmental and human health. Here, we analyse the regional evolution of DTR trend over different climatic zones in India using a non-stationary approach known as the Multidimensional Ensemble Empirical Mode Decomposition (MEEMD) method, to explore the generalized influence of regional climate on DTR, if any. We report a 0.36 °C increase in overall mean of DTR till 1980, however, the rate has declined since then. Further, arid deserts and warm-temperate grasslands exhibit negative DTR trends, while the west coast and sub-tropical forest in the north-east show positive trends. This transition predominantly begins with a 0.5 °C increase from the west coast and spreads with an increase of 0.25 °C per decade. These changes are more pronounced during winter and post-monsoon, especially in the arid desert and warm-temperate grasslands, the DTR decreased up to 2 °C, where the rate of increase in minimum temperature is higher than the maximum temperature. We conclude that both maximum and minimum temperature increase in response to the global climate change, however, their rates of increase are highly local and depend on the underlying climatic zone.

  6. The analysis of security cost for different energy sources

    International Nuclear Information System (INIS)

    Jun, Eunju; Kim, Wonjoon; Chang, Soon Heung

    2009-01-01

    Global concerns for the security of energy have steadily been on the increase and are expected to become a major issue over the next few decades. Urgent policy response is thus essential. However, little attempt has been made at defining both energy security and energy metrics. In this study, we provide such metrics and apply them to four major energy sources in the Korean electricity market: coal, oil, liquefied natural gas, and nuclear. In our approach, we measure the cost of energy security in terms of supply disruption and price volatility, and we consider the degree of concentration in energy supply and demand using the Hirschman-Herfindahl index (HHI). Due to its balanced fuel supply and demand, relatively stable price, and high abundance, we find nuclear energy to be the most competitive energy source in terms of energy security in the Korean electricity market. LNG, on the other hand, was found to have the highest cost in term of energy security due to its high concentration in supply and demand, and its high price volatility. In addition, in terms of cost, we find that economic security dominates supply security, and as such, it is the main factor in the total security cost. Within the confines of concern for global energy security, our study both broadens our understanding of energy security and enables a strategic approach in the portfolio management of energy consumption.

  7. Investigation of Different Configurations of a Ventilated Window to Optimize Both Energy Efficiency and Thermal Comfort

    DEFF Research Database (Denmark)

    Liu, Mingzhe; Heiselberg, Per; Larsen, Olena Kalyanova

    2017-01-01

    The study in this article investigates 15 ventilated window typologies with different pane configurations and glazing types in climates of four European countries (United Kingdom, Denmark, France and Germany) in order to identify the optimum typology with regard to their energy balance and impact...... on thermal comfort. Hourly simulations of the heat balances of the windows are conducted on four days representing different typical weather conditions according to the method described in EN ISO 13790. U and g values used in the calculation method are calculated in European software tool (WIS......) for the calculation of the thermal and solar properties of commercial and innovative window systems. Additionally, comfort performance is evaluated by inlet air temperature and internal surface temperature of the windows calculated by WIS software. The results of the study show the energy and comfort performance...

  8. Identification of hydrogen and deuterium at the surface of water ice by reflection electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    Yubero, F.; Toekesi, K.

    2009-01-01

    Complete text of publication follows. The study of elastically backscattered electrons from surfaces by reflection electron energy loss spectroscopy (REELS) has been recently recommended as an alternative technique to quantify the H content at the surface of a-C:H and polymer samples. This analysis is based on the fact that the energy loss of the incident electrons due to the recoil effect depends on the atomic mass of the particular atom present at the surface. The observed difference in recoil energies between H and O atoms (about 2 eV for 1.5 keV primary electrons) can be easily measured with standard electron spectrometers used in surface analysis. In this paper we go one step forward to explore if, with the same experimental approach, it is possible to differentiate between hydrogen and deuterium (D) in the surface region of a sample. This capability could be important for technological fields such as surface functionalization, where it is desired to distinguish between H and D at surfaces after interaction with labeled compounds. We have chosen normal and deuterated water as test labeled compounds because this polar molecule is of key importance in numerous surface reactions. It has been shown that H and D can be easily distinguished at the surface of water ice [4] using standard REELS measurements with 1000 - 1650 eV primary-electron energies, i.e., a surface analytical technique. Differences in recoil energies of the O - H and O - D atom pairs present in H 2 O and D 2 O have been found to agree with MC simulations (see Fig.1). There are many possible applications of H and D detection by REELS. Among many others, this study opens the possibility of nondestructive studies of deuterium-labeled atoms present or adsorbed on surfaces. For example, studies of H incorporation into a polymer or carbonbased surface after plasma activation with gas mixtures with several labeled molecules containing H atoms. Acknowledgements F.Y. thanks the Spanish Ministry of Science

  9. Extension of a He-H2 potential energy surface

    International Nuclear Information System (INIS)

    Raczkowski, A.W.; Lester, W.A. Jr.

    1977-01-01

    The CI surface of Tsapline and Kutzelnigg is extended to smaller H 2 -He separations. Defining R as the H 2 -He distance, r as the H 2 separation, and γ as the angle between them, the ab initio values are fit to a Legendre series in cosγ retaining the first three (even) terms with the coefficients given as analytic functions of R and r to facilitate semiclassical scattering computations. The fit is quantitative for 1.0 approximately r/2+1. (Auth.)

  10. Surface energy exchanges along a tundra-forest transition and feedbacks to climate

    Science.gov (United States)

    Beringer, J.; Chapin, F. S.; Thompson, Catharine Copass; McGuire, A.D.

    2005-01-01

    Surface energy exchanges were measured in a sequence of five sites representing the major vegetation types in the transition from arctic tundra to forest. This is the major transition in vegetation structure in northern high latitudes. We examined the influence of vegetation structure on the rates of sensible heating and evapotranspiration to assess the potential feedbacks to climate if high-latitude warming were to change the distribution of these vegetation types. Measurements were made at Council on the Seward Peninsula, Alaska, at representative tundra, low shrub, tall shrub, woodland (treeline), and boreal forest sites. Structural differences across the transition from tundra to forest included an increase in the leaf area index (LAI) from 0.52 to 2.76, an increase in canopy height from 0.1 to 6.1 m, and a general increase in canopy complexity. These changes in vegetation structure resulted in a decrease in albedo from 0.19 to 0.10 as well as changes to the partitioning of energy at the surface. Bulk surface resistance to water vapor flux remained virtually constant across sites, apparently because the combined soil and moss evaporation decreased while transpiration increased along the transect from tundra to forest. In general, sites became relatively warmer and drier along the transect with the convective fluxes being increasingly dominated by sensible heating, as evident by an increasing Bowen ratio from 0.94 to 1.22. The difference in growing season average daily sensible heating between tundra and forest was 21 W m-2. Fluxes changed non-linearly along the transition, with both shrubs and trees substantially enhancing heat transfer to the atmosphere. These changes in vegetation structure that increase sensible heating could feed back to enhance warming at local to regional scales. The magnitude of these vegetation effects on potential high-latitude warming is two to three times greater than suggested by previous modeling studies. ?? 2005 Elsevier B.V. All

  11. Shear-bond-strength of orthodontic brackets to aged nano-hybrid composite-resin surfaces using different surface preparation.

    Science.gov (United States)

    Demirtas, Hatice Kubra; Akin, Mehmet; Ileri, Zehra; Basciftci, Faruk Ayhan

    2015-01-01

    The aim of this study was to evaluate the effects of different surface preparation methods on the shear bond strength (SBS) of orthodontic metal brackets to aged nano-hybrid resin composite surfaces in vitro. A total of 100 restorative composite resin discs, 6 mm in diameter and 3 mm thick, were obtained and treated with an ageing procedure. After ageing, the samples were randomly divided as follows according to surface preparation methods: (1)Control, (2)37% phosphoric acid gel, (3)Sandblasting, (4)Diamond bur, (5)Air-flow and 20 central incisor teeth were used for the control etched group. SBS test were applied on bonded metal brackets to all samples. SBS values and residual adhesives were evaluated. Analysis of variance showed a significant difference (porthodontic metal brackets to nano-hybrid composite resin surfaces.

  12. The influence of different dietary energy concentrations on the ...

    African Journals Online (AJOL)

    Energy is essential for the continuous survival of any living organism. In ostrich diets, energy is usually derived from maize, which is often subject to fluctuations in yield as a result of drought conditions. Therefore, the optimal utilization of energy in the diets of ostriches becomes of paramount importance, but without affecting ...

  13. Effect of different surface treatments on bond strength, surface and microscopic structure of zirconia ceramic

    Directory of Open Access Journals (Sweden)

    Zeinab R. El-Shrkawy

    2016-06-01

    Conclusions: (1 Surface treatments of Y-TZP ceramic together with MDP primer and silane-coupling agent application improve the bond strength to resin cement. (2 Plasma-Silica coating and plasma-oxygen treatment, both are valuable methods that improve the bond strength of resin cement to Y-TZP ceramic. (3 Silica coating by plasma technology provides durable bond strength and can be a promising alternative pretreatment before silane application to enhance bonding with zirconia ceramic. (4 Tetragonal-monoclinic phase transformation had occurred in Y-TZP samples received both types of plasma treatment.

  14. Field use of D218O to measure energy expenditure of soldiers at different energy intakes

    International Nuclear Information System (INIS)

    DeLany, J.P.; Schoeller, D.A.; Hoyt, R.W.; Askew, E.W.; Sharp, M.A.

    1989-01-01

    To test the application of doubly labeled water under adverse field conditions, energy expenditures of 16 special operations soldiers were measured during a 28-day field training exercise. Subjects were matched by fat-free mass and divided equally between an ad libitum ready-to-eat meal diet and a 2,000 kcal/day lightweight ration. Subjects recorded intakes daily, and body composition was measured before and after the exercise. At the beginning of the study, subjects moved to a new northerly location and, therefore, a new water supply. To compensate for this, a group of soldiers who did not receive heavy water was followed to measure isotopic base-line changes. Energy expenditure by doubly labeled water was in agreement with intake/balance (3,400 ± 260 vs. 3,230 ± 520 kcal/day). The overall coefficient of variation of energy expenditure by doubly labeled water was half that of intake/balance (7.6 vs. 16.1%). The coefficient of variation of repeat measures with doubly labeled water was 7.3%. Energy expenditure of the ready-to-eat meal group, 3,540 ± 180 kcal/day, was not significantly different from the lightweight ration group, 3,330 ± 301 kcal/day. Doubly labeled water was valid under field conditions

  15. Oxathiiranes 8 On the OCS2 Singlet Potential Energy Surface

    DEFF Research Database (Denmark)

    Carlsen, Lars

    1982-01-01

    The reaction between atomic oxygen and carbon disulfide is predicted to lead to at least two primary products, which are the dithiiranone (1) and the oxathiirane-thione (2) and/or the carbon disulfide S-oxide (4). The possible intramolecular equilibria 1 ⇄ 2, 1 ⇄ 3, 2 ⇄ 4, and 2 ⇄ 5 as well...... as the fragmentations of the possible intermediates 1–5 have been studied theoretically within the semiempirical cndo/B framework as conceivable ground-state reactions. On the basis of mo correlations and potential energy changes along the reaction paths, supplementary with previously reported experimental data...

  16. Laser treatment of dental ceramic/cement layers: transmitted energy, temperature effects and surface characterisation.

    Science.gov (United States)

    Pich, Olena; Franzen, René; Gutknecht, Norbert; Wolfart, Stefan

    2015-02-01

    In the present paper, we investigate the behaviour of different dental materials under laser irradiation. We have used e.max Ceram, e.max ZirCAD, and e.max Press dental ceramics and glass ionomer cement Ketac Cem in the present study. The dental ceramics were prepared in the form of samples with thickness of 0.5-2 mm. We used two lasers [solid-state laser (Er:YAG, Fidelis III+, Fotona) and an 810- nm diode laser (FOX, A.R.C)] for the transillumination of ceramic samples. It has been shown that the laser energy transmitted through the ceramic material decreases to 30-40% of the original values along with an increase in the thickness of the irradiated sample. Pigmented ceramic samples show more laser energy loss compared to the samples containing no pigment. We investigated the temperature evolution in composite sandwiched ceramic/cement samples under laser treatment. The increase in the irradiation time and laser power led to a temperature increase of up to 80 °C. The surfaces of irradiated ceramic samples were examined with X-ray photoelectron spectroscopy to evaluate changes in chemical composition, such as a decrease in the C signal, accompanied by a strong increase in the Zr peak for the Er:YAG laser, while the 810-nm diode laser showed no change in the ratio of elements on the surface.

  17. Surface potential measurement of negative-ion-implanted insulators by analysing secondary electron energy distribution

    International Nuclear Information System (INIS)

    Toyota, Yoshitaka; Tsuji, Hiroshi; Nagumo, Syoji; Gotoh, Yasuhito; Ishikawa, Junzo; Sakai, Shigeki.

    1994-01-01

    The negative ion implantation method we have proposed is a noble technique which can reduce surface charging of isolated electrodes by a large margin. In this paper, the way to specify the surface potential of negative-ion-implanted insulators by the secondary electron energy analysis is described. The secondary electron energy distribution is obtained by a retarding field type energy analyzer. The result shows that the surface potential of fused quartz by negative-ion implantation (C - with the energy of 10 keV to 40 keV) is negatively charged by only several volts. This surface potential is extremely low compared with that by positive-ion implantation. Therefore, the negative-ion implantation is a very effective method for charge-up free implantation without charge compensation. (author)

  18. Discrete lattice plane broken bond interfacial energy calculations and the use of the dividing surface concept

    International Nuclear Information System (INIS)

    Ramanujan, R.V.

    2003-01-01

    The concept of the dividing surface has been extensively used to define the relationships between thermodynamic quantities at the interface between two phases; it is also useful in calculations of interfacial energy (γ). However, in the original formulation, the two phases are continuum phases, the atomistic nature of the interface was not considered. It is, therefore, useful to examine the use of the dividing surface in the context of atomistic interfacial energy calculations. The case of a planar fcc:hcp interface is considered and the dividing surface positions which are useful in atomistic interfacial energy calculations are stated, one position equates γ to the excess internal energy, the other position allows us to use the Gibbs adsorption equation. An example of a calculation using the convenient dividing surface positions is presented

  19. Relation between bulk compressibility and surface energy of electron-hole liquids

    International Nuclear Information System (INIS)

    Singwi, K.S.; Tosi, M.P.

    1979-08-01

    Attention is drawn to the existence of an empirical relation chiσ/asup(*)sub(B) approximately 1 between the compressibility, the surface energy and the excitonic radius in electron-hole liquids. (author)

  20. Energy storage considerations for a robotic Mars surface sampler

    International Nuclear Information System (INIS)

    O'Donnell, P.M.; Cataldo, R.L.; Gonzalez-Sanabria, O.D.

    1988-01-01

    Manned exploration of Mars is being proposed by the National Commission on Space for the next century. To accomplish this task with minimal resupply cost for extended stay times, use of Mars' resources is essential. Methods must be developed to manufacture or extract water and oxygen from elements indigenous to Mars before they send explorers to the planet. Therefore, they must send precursor surveying equipment to determine Mars' resources to a greater extent than is now known from Viking 1 and Viking 2 data. A 1992 launch is planned for the Mars Observer that will contribute greater mapping resolution and expand the scientific data base. The proposed rover will provide scientists with the necessary information about abundant resources that would guide the required technology development needed to support a manned Mars infrastructure. The actual rover operations plan for both the sample return and extended mission will have a large impact on rover capabilities and the power system supplying power for traversing and scientific instrumentation. POWER SOURCE AND CONVERSION. Several power source/conversion options for the rover have been identified. These include power generation on the lander, Entry Vehicle (EV), Mars Orbiter Vehicle (MOV) and on the rover itself. Power from the lander would require the rover to return to landing site to recharge the energy storage systems, which limits rover excursions to one-half the range of the storage capacity. For on-board rover power, a Radioisotope Thermoelectric Generator (RTG) has been considered with the appropriate energy storage to handle peak power demands

  1. Characterizing water-metal interfaces and machine learning potential energy surfaces

    Science.gov (United States)

    Ryczko, Kevin

    In this thesis, we first discuss the fundamentals of ab initio electronic structure theory and density functional theory (DFT). We also discuss statistics related to computing thermodynamic averages of molecular dynamics (MD). We then use this theory to analyze and compare the structural, dynamical, and electronic properties of liquid water next to prototypical metals including platinum, graphite, and graphene. Our results are built on Born-Oppenheimer molecular dynamics (BOMD) generated using density functional theory (DFT) which explicitly include van der Waals (vdW) interactions within a first principles approach. All calculations reported use large simulation cells, allowing for an accurate treatment of the water-electrode interfaces. We have included vdW interactions through the use of the optB86b-vdW exchange correlation functional. Comparisons with the Perdew-Burke-Ernzerhof (PBE) exchange correlation functional are also shown. We find an initial peak, due to chemisorption, in the density profile of the liquid water-Pt interface not seen in the liquid water-graphite interface, liquid watergraphene interface, nor interfaces studied previously. To further investigate this chemisorption peak, we also report differences in the electronic structure of single water molecules on both Pt and graphite surfaces. We find that a covalent bond forms between the single water molecule and the platinum surface, but not between the single water molecule and the graphite surface. We also discuss the effects that defects and dopants in the graphite and graphene surfaces have on the structure and dynamics of liquid water. Lastly, we introduce artificial neural networks (ANNs), and demonstrate how they can be used to machine learn electronic structure calculations. As a proof of principle, we show the success of an ANN potential energy surfaces for a